man/, share/mk/: Move man*/ to man/

This is a scripted change:

$ mkdir man/;
$ mv man* man/;
$ ln -st . man/man*;
$ find share/mk/ -type f \
	| xargs grep -l '^MANDIR *:=' \
	| xargs sed -i '/^MANDIR *:=/s,$,/man,';
$ find share/mk/dist/ -type f \
	| xargs grep -l man \
	| xargs sed -i 's,man%,man/%,g';

Link: <https://lore.kernel.org/linux-man/YxcV4h+Xn7cd6+q2@pevik/T/>
Cc: Petr Vorel <pvorel@suse.cz>
Cc: Jakub Wilk <jwilk@jwilk.net>
Cc: Stefan Puiu <stefan.puiu@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

2699 files changed, 290672 insertions, 0 deletions

diff --git a/man/man1/getent.1 b/man/man1/getent.1
new file mode 100644
index 000000000..8efbbe51a
--- /dev/null
+++ b/man/man1/getent.1
@@ -0,0 +1,387 @@
+.\" Copyright (c) 2011, Mark R. Bannister <cambridge@users.sourceforge.net>
+.\" Copyright (c) 2015, Robin H. Johnson <robbat2@gentoo.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH getent 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getent \- get entries from Name Service Switch libraries
+.SH SYNOPSIS
+.nf
+.B getent [\fIoption\fP]... \fIdatabase\fP \fIkey\fP...
+.fi
+.SH DESCRIPTION
+The
+.B getent
+command displays entries from databases supported by the
+Name Service Switch libraries,
+which are configured in
+.IR /etc/nsswitch.conf .
+If one or more
+.I key
+arguments are provided,
+then only the entries that match the supplied keys will be displayed.
+Otherwise, if no
+.I key
+is provided, all entries will be displayed (unless the database does not
+support enumeration).
+.P
+The
+.I database
+may be any of those supported by the GNU C Library, listed below:
+.TP
+.B ahosts
+When no
+.I key
+is provided, use
+.BR sethostent (3),
+.BR gethostent (3),
+and
+.BR endhostent (3)
+to enumerate the hosts database.
+This is identical to using
+.BR hosts (5).
+When one or more
+.I key
+arguments are provided, pass each
+.I key
+in succession to
+.BR getaddrinfo (3)
+with the address family
+.BR AF_UNSPEC ,
+enumerating each socket address structure returned.
+.TP
+.B ahostsv4
+Same as
+.BR ahosts ,
+but use the address family
+.BR AF_INET .
+.TP
+.B ahostsv6
+Same as
+.BR ahosts ,
+but use the address family
+.BR AF_INET6 .
+The call to
+.BR getaddrinfo (3)
+in this case includes the
+.B AI_V4MAPPED
+flag.
+.TP
+.B aliases
+When no
+.I key
+is provided, use
+.BR setaliasent (3),
+.BR getaliasent (3),
+and
+.BR endaliasent (3)
+to enumerate the aliases database.
+When one or more
+.I key
+arguments are provided, pass each
+.I key
+in succession to
+.BR getaliasbyname (3)
+and display the result.
+.TP
+.B ethers
+When one or more
+.I key
+arguments are provided, pass each
+.I key
+in succession to
+.BR ether_aton (3)
+and
+.BR ether_hostton (3)
+until a result is obtained, and display the result.
+Enumeration is not supported on
+.BR ethers ,
+so a
+.I key
+must be provided.
+.TP
+.B group
+When no
+.I key
+is provided, use
+.BR setgrent (3),
+.BR getgrent (3),
+and
+.BR endgrent (3)
+to enumerate the group database.
+When one or more
+.I key
+arguments are provided, pass each numeric
+.I key
+to
+.BR getgrgid (3)
+and each nonnumeric
+.I key
+to
+.BR getgrnam (3)
+and display the result.
+.TP
+.B gshadow
+When no
+.I key
+is provided, use
+.BR setsgent (3),
+.BR getsgent (3),
+and
+.BR endsgent (3)
+to enumerate the gshadow database.
+When one or more
+.I key
+arguments are provided, pass each
+.I key
+in succession to
+.BR getsgnam (3)
+and display the result.
+.TP
+.B hosts
+When no
+.I key
+is provided, use
+.BR sethostent (3),
+.BR gethostent (3),
+and
+.BR endhostent (3)
+to enumerate the hosts database.
+When one or more
+.I key
+arguments are provided, pass each
+.I key
+to
+.BR gethostbyaddr (3)
+or
+.BR gethostbyname2 (3),
+depending on whether a call to
+.BR inet_pton (3)
+indicates that the
+.I key
+is an IPv6 or IPv4 address or not, and display the result.
+.TP
+.B initgroups
+When one or more
+.I key
+arguments are provided, pass each
+.I key
+in succession to
+.BR getgrouplist (3)
+and display the result.
+Enumeration is not supported on
+.BR initgroups ,
+so a
+.I key
+must be provided.
+.TP
+.B netgroup
+When one
+.I key
+is provided, pass the
+.I key
+to
+.BR setnetgrent (3)
+and, using
+.BR getnetgrent (3)
+display the resulting string triple
+.RI ( hostname ", " username ", " domainname ).
+Alternatively, three
+.I keys
+may be provided, which are interpreted as the
+.IR hostname ,
+.IR username ,
+and
+.I domainname
+to match to a netgroup name via
+.BR innetgr (3).
+Enumeration is not supported on
+.BR netgroup ,
+so either one or three
+.I keys
+must be provided.
+.TP
+.B networks
+When no
+.I key
+is provided, use
+.BR setnetent (3),
+.BR getnetent (3),
+and
+.BR endnetent (3)
+to enumerate the networks database.
+When one or more
+.I key
+arguments are provided, pass each numeric
+.I key
+to
+.BR getnetbyaddr (3)
+and each nonnumeric
+.I key
+to
+.BR getnetbyname (3)
+and display the result.
+.TP
+.B passwd
+When no
+.I key
+is provided, use
+.BR setpwent (3),
+.BR getpwent (3),
+and
+.BR endpwent (3)
+to enumerate the passwd database.
+When one or more
+.I key
+arguments are provided, pass each numeric
+.I key
+to
+.BR getpwuid (3)
+and each nonnumeric
+.I key
+to
+.BR getpwnam (3)
+and display the result.
+.TP
+.B protocols
+When no
+.I key
+is provided, use
+.BR setprotoent (3),
+.BR getprotoent (3),
+and
+.BR endprotoent (3)
+to enumerate the protocols database.
+When one or more
+.I key
+arguments are provided, pass each numeric
+.I key
+to
+.BR getprotobynumber (3)
+and each nonnumeric
+.I key
+to
+.BR getprotobyname (3)
+and display the result.
+.TP
+.B rpc
+When no
+.I key
+is provided, use
+.BR setrpcent (3),
+.BR getrpcent (3),
+and
+.BR endrpcent (3)
+to enumerate the rpc database.
+When one or more
+.I key
+arguments are provided, pass each numeric
+.I key
+to
+.BR getrpcbynumber (3)
+and each nonnumeric
+.I key
+to
+.BR getrpcbyname (3)
+and display the result.
+.TP
+.B services
+When no
+.I key
+is provided, use
+.BR setservent (3),
+.BR getservent (3),
+and
+.BR endservent (3)
+to enumerate the services database.
+When one or more
+.I key
+arguments are provided, pass each numeric
+.I key
+to
+.BR getservbynumber (3)
+and each nonnumeric
+.I key
+to
+.BR getservbyname (3)
+and display the result.
+.TP
+.B shadow
+When no
+.I key
+is provided, use
+.BR setspent (3),
+.BR getspent (3),
+and
+.BR endspent (3)
+to enumerate the shadow database.
+When one or more
+.I key
+arguments are provided, pass each
+.I key
+in succession to
+.BR getspnam (3)
+and display the result.
+.SH OPTIONS
+.TP
+.BI \-\-service\~ service
+.TQ
+.BI \-s\~ service
+.\" commit 9d0881aa76b399e6a025c5cf44bebe2ae0efa8af (glibc)
+Override all databases with the specified service.
+(Since glibc 2.2.5.)
+.TP
+.BI \-\-service\~ database : service
+.TQ
+.BI \-s\~ database : service
+.\" commit b4f6f4be85d32b9c03361c38376e36f08100e3e8 (glibc)
+Override only specified databases with the specified service.
+The option may be used multiple times,
+but only the last service for each database will be used.
+(Since glibc 2.4.)
+.TP
+.B \-\-no\-idn
+.TQ
+.B \-i
+.\" commit a160f8d808cf8020b13bd0ef4a9eaf3c11f964ad (glibc)
+Disables IDN encoding in lookups for
+.BR ahosts / getaddrinfo (3)
+(Since glibc-2.13.)
+.TP
+.B \-\-help
+.TQ
+.B \-?
+Print a usage summary and exit.
+.TP
+.B \-\-usage
+Print a short usage summary and exit.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Print the version number, license, and disclaimer of warranty for
+.BR getent .
+.SH EXIT STATUS
+One of the following exit values can be returned by
+.BR getent :
+.TP
+.B 0
+Command completed successfully.
+.TP
+.B 1
+Missing arguments, or
+.I database
+unknown.
+.TP
+.B 2
+One or more supplied
+.I key
+could not be found in the
+.IR database .
+.TP
+.B 3
+Enumeration not supported on this
+.IR database .
+.SH SEE ALSO
+.BR nsswitch.conf (5)
diff --git a/man/man1/iconv.1 b/man/man1/iconv.1
new file mode 100644
index 000000000..eaa18c0f9
--- /dev/null
+++ b/man/man1/iconv.1
@@ -0,0 +1,204 @@
+.\" Copyright (C) 2014 Marko Myllynen <myllynen@redhat.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH iconv 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iconv \- convert text from one character encoding to another
+.SH SYNOPSIS
+.B iconv
+.RI [ options ]
+.RI "[\-f " from-encoding "]"
+.RI "[\-t " to-encoding "]"
+.RI [ inputfile ]...
+.SH DESCRIPTION
+The
+.B iconv
+program reads in text in one encoding and outputs the text in another
+encoding.
+If no input files are given, or if it is given as a dash (\-),
+.B iconv
+reads from standard input.
+If no output file is given,
+.B iconv
+writes to standard output.
+.P
+If no
+.I from-encoding
+is given, the default is derived
+from the current locale's character encoding.
+If no
+.I to-encoding
+is given, the default is derived
+from the current locale's character
+encoding.
+.SH OPTIONS
+.TP
+.BI \-\-from\-code= from-encoding
+.TQ
+.BI \-f\~ from-encoding
+Use
+.I from-encoding
+for input characters.
+.TP
+.BI \-\-to\-code= to-encoding
+.TQ
+.BI \-t\~ to-encoding
+Use
+.I to-encoding
+for output characters.
+.IP
+If the string
+.B //IGNORE
+is appended to
+.IR to-encoding ,
+characters that cannot be converted are discarded and an error is
+printed after conversion.
+.IP
+If the string
+.B //TRANSLIT
+is appended to
+.IR to-encoding ,
+characters being converted are transliterated when needed and possible.
+This means that when a character cannot be represented in the target
+character set, it can be approximated through one or several similar
+looking characters.
+Characters that are outside of the target character set and cannot be
+transliterated are replaced with a question mark (?) in the output.
+.TP
+.B \-\-list
+.TQ
+.B \-l
+List all known character set encodings.
+.TP
+.B \-c
+Silently discard characters that cannot be converted instead of
+terminating when encountering such characters.
+.TP
+.BI \-\-output= outputfile
+.TQ
+.BI \-o\~ outputfile
+Use
+.I outputfile
+for output.
+.TP
+.B \-\-silent
+.TQ
+.B \-s
+This option is ignored; it is provided only for compatibility.
+.TP
+.B \-\-verbose
+Print progress information on standard error when processing
+multiple files.
+.TP
+.B \-\-help
+.TQ
+.B \-?
+Print a usage summary and exit.
+.TP
+.B \-\-usage
+Print a short usage summary and exit.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Print the version number, license, and disclaimer of warranty for
+.BR iconv .
+.SH EXIT STATUS
+Zero on success, nonzero on errors.
+.SH ENVIRONMENT
+Internally, the
+.B iconv
+program uses the
+.BR iconv (3)
+function which in turn uses
+.I gconv
+modules (dynamically loaded shared libraries)
+to convert to and from a character set.
+Before calling
+.BR iconv (3),
+the
+.B iconv
+program must first allocate a conversion descriptor using
+.BR iconv_open (3).
+The operation of the latter function is influenced by the setting of the
+.B GCONV_PATH
+environment variable:
+.IP \[bu] 3
+If
+.B GCONV_PATH
+is not set,
+.BR iconv_open (3)
+loads the system gconv module configuration cache file created by
+.BR iconvconfig (8)
+and then, based on the configuration,
+loads the gconv modules needed to perform the conversion.
+If the system gconv module configuration cache file is not available
+then the system gconv module configuration file is used.
+.IP \[bu]
+If
+.B GCONV_PATH
+is defined (as a colon-separated list of pathnames),
+the system gconv module configuration cache is not used.
+Instead,
+.BR iconv_open (3)
+first tries to load the configuration files by searching the directories in
+.B GCONV_PATH
+in order,
+followed by the system default gconv module configuration file.
+If a directory does not contain a gconv module configuration file,
+any gconv modules that it may contain are ignored.
+If a directory contains a gconv module configuration file
+and it is determined that a module needed for this conversion is
+available in the directory,
+then the needed module is loaded from that directory,
+the order being such that the first suitable module found in
+.B GCONV_PATH
+is used.
+This allows users to use custom modules and even replace system-provided
+modules by providing such modules in
+.B GCONV_PATH
+directories.
+.SH FILES
+.TP
+.I /usr/lib/gconv
+Usual default gconv module path.
+.TP
+.I /usr/lib/gconv/gconv\-modules
+Usual system default gconv module configuration file.
+.TP
+.I /usr/lib/gconv/gconv\-modules.cache
+Usual system gconv module configuration cache.
+.P
+Depending on the architecture,
+the above files may instead be located at directories with the path prefix
+.IR /usr/lib64 .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+Convert text from the ISO/IEC\~8859-15 character encoding to UTF-8:
+.P
+.in +4n
+.EX
+$ \fBiconv \-f ISO\-8859\-15 \-t UTF\-8 < input.txt > output.txt\fP
+.EE
+.in
+.P
+The next example converts from UTF-8 to ASCII, transliterating when
+possible:
+.P
+.in +4n
+.EX
+$ \fBecho abc ß α € àḃç | iconv \-f UTF\-8 \-t ASCII//TRANSLIT\fP
+abc ss ? EUR abc
+.EE
+.in
+.SH SEE ALSO
+.BR locale (1),
+.BR uconv (1),
+.BR iconv (3),
+.BR nl_langinfo (3),
+.BR charsets (7),
+.BR iconvconfig (8)
diff --git a/man/man1/intro.1 b/man/man1/intro.1
new file mode 100644
index 000000000..decaab161
--- /dev/null
+++ b/man/man1/intro.1
@@ -0,0 +1,305 @@
+.\" Copyright (c) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH intro 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to user commands
+.SH DESCRIPTION
+Section 1 of the manual describes user commands and tools,
+for example, file manipulation tools, shells, compilers,
+web browsers, file and image viewers and editors, and so on.
+.SH NOTES
+Linux is a flavor of UNIX, and as a first approximation
+all user commands under UNIX work precisely the same under
+Linux (and FreeBSD and lots of other UNIX-like systems).
+.P
+Under Linux, there are GUIs (graphical user interfaces), where you
+can point and click and drag, and hopefully get work done without
+first reading lots of documentation.
+The traditional UNIX environment
+is a CLI (command line interface), where you type commands to
+tell the computer what to do.
+That is faster and more powerful,
+but requires finding out what the commands are.
+Below a bare minimum, to get started.
+.SS Login
+In order to start working, you probably first have to open a session by
+giving your username and password.
+The program
+.BR login (1)
+now starts a
+.I shell
+(command interpreter) for you.
+In case of a graphical login, you get a screen with menus or icons
+and a mouse click will start a shell in a window.
+See also
+.BR xterm (1).
+.SS The shell
+One types commands to the
+.IR shell ,
+the command interpreter.
+It is not built-in, but is just a program
+and you can change your shell.
+Everybody has their own favorite one.
+The standard one is called
+.IR sh .
+See also
+.BR ash (1),
+.BR bash (1),
+.BR chsh (1),
+.BR csh (1),
+.BR dash (1),
+.BR ksh (1),
+.BR zsh (1).
+.P
+A session might go like:
+.P
+.in +4n
+.EX
+.RB "knuth login: " aeb
+.RB "Password: " ********
+.RB "$ " date
+Tue Aug  6 23:50:44 CEST 2002
+.RB "$ " cal
+     August 2002
+Su Mo Tu We Th Fr Sa
+             1  2  3
+ 4  5  6  7  8  9 10
+11 12 13 14 15 16 17
+18 19 20 21 22 23 24
+25 26 27 28 29 30 31
+\&
+.RB "$ " ls
+bin  tel
+.RB "$ " "ls \-l"
+total 2
+drwxrwxr\-x   2 aeb       1024 Aug  6 23:51 bin
+\-rw\-rw\-r\-\-   1 aeb         37 Aug  6 23:52 tel
+.RB "$ " "cat tel"
+maja    0501\-1136285
+peter   0136\-7399214
+.RB "$ " "cp tel tel2"
+.RB "$ " "ls \-l"
+total 3
+drwxr\-xr\-x   2 aeb       1024 Aug  6 23:51 bin
+\-rw\-r\-\-r\-\-   1 aeb         37 Aug  6 23:52 tel
+\-rw\-r\-\-r\-\-   1 aeb         37 Aug  6 23:53 tel2
+.RB "$ " "mv tel tel1"
+.RB "$ " "ls \-l"
+total 3
+drwxr\-xr\-x   2 aeb       1024 Aug  6 23:51 bin
+\-rw\-r\-\-r\-\-   1 aeb         37 Aug  6 23:52 tel1
+\-rw\-r\-\-r\-\-   1 aeb         37 Aug  6 23:53 tel2
+.RB "$ " "diff tel1 tel2"
+.RB "$ " "rm tel1"
+.RB "$ " "grep maja tel2"
+maja    0501\-1136285
+$
+.EE
+.in
+.P
+Here typing Control-D ended the session.
+.P
+The
+.B $
+here was the command prompt\[em]it is the shell's way of indicating
+that it is ready for the next command.
+The prompt can be customized
+in lots of ways, and one might include stuff like username,
+machine name, current directory, time, and so on.
+An assignment PS1="What next, master? "
+would change the prompt as indicated.
+.P
+We see that there are commands
+.I date
+(that gives date and time), and
+.I cal
+(that gives a calendar).
+.P
+The command
+.I ls
+lists the contents of the current directory\[em]it tells you what
+files you have.
+With a
+.I \-l
+option it gives a long listing,
+that includes the owner and size and date of the file, and the
+permissions people have for reading and/or changing the file.
+For example, the file "tel" here is 37 bytes long, owned by aeb
+and the owner can read and write it, others can only read it.
+Owner and permissions can be changed by the commands
+.I chown
+and
+.IR chmod .
+.P
+The command
+.I cat
+will show the contents of a file.
+(The name is from "concatenate and print": all files given as
+parameters are concatenated and sent to "standard output"
+(see
+.BR stdout (3)),
+here
+the terminal screen.)
+.P
+The command
+.I cp
+(from "copy") will copy a file.
+.P
+The command
+.I mv
+(from "move"), on the other hand, only renames it.
+.P
+The command
+.I diff
+lists the differences between two files.
+Here there was no output because there were no differences.
+.P
+The command
+.I rm
+(from "remove") deletes the file, and be careful! it is gone.
+No wastepaper basket or anything.
+Deleted means lost.
+.P
+The command
+.I grep
+(from "g/re/p") finds occurrences of a string in one or more files.
+Here it finds Maja's telephone number.
+.SS Pathnames and the current directory
+Files live in a large tree, the file hierarchy.
+Each has a
+.I "pathname"
+describing the path from the root of the tree (which is called
+.IR / )
+to the file.
+For example, such a full pathname might be
+.IR /home/aeb/tel .
+Always using full pathnames would be inconvenient, and the name
+of a file in the current directory may be abbreviated by giving
+only the last component.
+That is why
+.I /home/aeb/tel
+can be abbreviated
+to
+.I tel
+when the current directory is
+.IR /home/aeb .
+.P
+The command
+.I pwd
+prints the current directory.
+.P
+The command
+.I cd
+changes the current directory.
+.P
+Try alternatively
+.I cd
+and
+.I pwd
+commands and explore
+.I cd
+usage: "cd", "cd .", "cd ..", "cd /", and "cd \[ti]".
+.SS Directories
+The command
+.I mkdir
+makes a new directory.
+.P
+The command
+.I rmdir
+removes a directory if it is empty, and complains otherwise.
+.P
+The command
+.I find
+(with a rather baroque syntax) will find files with given name
+or other properties.
+For example, "find . \-name tel" would find
+the file
+.I tel
+starting in the present directory (which is called
+.IR . ).
+And "find / \-name tel" would do the same, but starting at the root
+of the tree.
+Large searches on a multi-GB disk will be time-consuming,
+and it may be better to use
+.BR locate (1).
+.SS Disks and filesystems
+The command
+.I mount
+will attach the filesystem found on some disk (or floppy, or CDROM or so)
+to the big filesystem hierarchy.
+And
+.I umount
+detaches it again.
+The command
+.I df
+will tell you how much of your disk is still free.
+.SS Processes
+On a UNIX system many user and system processes run simultaneously.
+The one you are talking to runs in the
+.IR foreground ,
+the others in the
+.IR background .
+The command
+.I ps
+will show you which processes are active and what numbers these
+processes have.
+The command
+.I kill
+allows you to get rid of them.
+Without option this is a friendly
+request: please go away.
+And "kill \-9" followed by the number
+of the process is an immediate kill.
+Foreground processes can often be killed by typing Control-C.
+.SS Getting information
+There are thousands of commands, each with many options.
+Traditionally commands are documented on
+.IR "man pages" ,
+(like this one), so that the command "man kill" will document
+the use of the command "kill" (and "man man" document the command "man").
+The program
+.I man
+sends the text through some
+.IR pager ,
+usually
+.IR less .
+Hit the space bar to get the next page, hit q to quit.
+.P
+In documentation it is customary to refer to man pages
+by giving the name and section number, as in
+.BR man (1).
+Man pages are terse, and allow you to find quickly some forgotten
+detail.
+For newcomers an introductory text with more examples
+and explanations is useful.
+.P
+A lot of GNU/FSF software is provided with info files.
+Type "info info"
+for an introduction on the use of the program
+.IR info .
+.P
+Special topics are often treated in HOWTOs.
+Look in
+.I /usr/share/doc/howto/en
+and use a browser if you find HTML files there.
+.\"
+.\" Actual examples? Separate section for each of cat, cp, ...?
+.\" gzip, bzip2, tar, rpm
+.SH SEE ALSO
+.BR ash (1),
+.BR bash (1),
+.BR chsh (1),
+.BR csh (1),
+.BR dash (1),
+.BR ksh (1),
+.BR locate (1),
+.BR login (1),
+.BR man (1),
+.BR xterm (1),
+.BR zsh (1),
+.BR wait (2),
+.BR stdout (3),
+.BR man\-pages (7),
+.BR standards (7)
diff --git a/man/man1/ldd.1 b/man/man1/ldd.1
new file mode 100644
index 000000000..57e9b40eb
--- /dev/null
+++ b/man/man1/ldd.1
@@ -0,0 +1,180 @@
+.\" Copyright 1995-2000 David Engel (david@ods.com)
+.\" Copyright 1995 Rickard E. Faith (faith@cs.unc.edu)
+.\" Copyright 2000 Ben Collins (bcollins@debian.org)
+.\"    Redone for glibc 2.2
+.\" Copyright 2000 Jakub Jelinek (jakub@redhat.com)
+.\"    Corrected.
+.\" and Copyright (C) 2012, 2016, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH ldd 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ldd \- print shared object dependencies
+.SH SYNOPSIS
+.nf
+.BR ldd " [\fIoption\fP]... \fIfile\fP..."
+.fi
+.SH DESCRIPTION
+.B ldd
+prints the shared objects (shared libraries) required by each program or
+shared object specified on the command line.
+An example of its use and output
+is the following:
+.P
+.in +4n
+.EX
+$ \fBldd /bin/ls\fP
+    linux\-vdso.so.1 (0x00007ffcc3563000)
+    libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f87e5459000)
+    libcap.so.2 => /lib64/libcap.so.2 (0x00007f87e5254000)
+    libc.so.6 => /lib64/libc.so.6 (0x00007f87e4e92000)
+    libpcre.so.1 => /lib64/libpcre.so.1 (0x00007f87e4c22000)
+    libdl.so.2 => /lib64/libdl.so.2 (0x00007f87e4a1e000)
+    /lib64/ld\-linux\-x86\-64.so.2 (0x00005574bf12e000)
+    libattr.so.1 => /lib64/libattr.so.1 (0x00007f87e4817000)
+    libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f87e45fa000)
+.EE
+.in
+.P
+In the usual case,
+.B ldd
+invokes the standard dynamic linker (see
+.BR ld.so (8))
+with the
+.B LD_TRACE_LOADED_OBJECTS
+environment variable set to 1.
+This causes the dynamic linker to inspect the program's dynamic dependencies,
+and find (according to the rules described in
+.BR ld.so (8))
+and load the objects that satisfy those dependencies.
+For each dependency,
+.B ldd
+displays the location of the matching object
+and the (hexadecimal) address at which it is loaded.
+(The
+.I linux\-vdso
+and
+.I ld\-linux
+shared dependencies are special; see
+.BR vdso (7)
+and
+.BR ld.so (8).)
+.\"
+.SS Security
+Be aware that in some circumstances
+(e.g., where the program specifies an ELF interpreter other than
+.IR ld\-linux.so ),
+.\" The circumstances are where the program has an interpreter
+.\" other than ld-linux.so. In this case, ldd tries to execute the
+.\" program directly with LD_TRACE_LOADED_OBJECTS=1, with the
+.\" result that the program interpreter gets control, and can do
+.\" what it likes, or pass control to the program itself.
+.\" Much more detail at
+.\" http://www.catonmat.net/blog/ldd-arbitrary-code-execution/
+some versions of
+.B ldd
+may attempt to obtain the dependency information
+by attempting to directly execute the program,
+which may lead to the execution of whatever code is defined
+in the program's ELF interpreter,
+and perhaps to execution of the program itself.
+.\" Mainline glibc's ldd allows this possibility (the line
+.\"      try_trace "$file"
+.\" in glibc 2.15, for example), but many distro versions of
+.\" ldd seem to remove that code path from the script.
+(Before glibc 2.27,
+.\" glibc commit eedca9772e99c72ab4c3c34e43cc764250aa3e3c
+the upstream
+.B ldd
+implementation did this for example,
+although most distributions provided a modified version that did not.)
+.P
+Thus, you should
+.I never
+employ
+.B ldd
+on an untrusted executable,
+since this may result in the execution of arbitrary code.
+A safer alternative when dealing with untrusted executables is:
+.P
+.in +4n
+.EX
+$ \fBobjdump \-p /path/to/program | grep NEEDED\fP
+.EE
+.in
+.P
+Note, however, that this alternative shows only the direct dependencies
+of the executable, while
+.B ldd
+shows the entire dependency tree of the executable.
+.SH OPTIONS
+.TP
+.B \-\-version
+Print the version number of
+.BR ldd .
+.TP
+.B \-\-verbose
+.TQ
+.B \-v
+Print all information, including, for example,
+symbol versioning information.
+.TP
+.B \-\-unused
+.TQ
+.B \-u
+Print unused direct dependencies.
+(Since glibc 2.3.4.)
+.TP
+.B \-\-data\-relocs
+.TQ
+.B \-d
+Perform relocations and report any missing objects (ELF only).
+.TP
+.B \-\-function\-relocs
+.TQ
+.B \-r
+Perform relocations for both data objects and functions, and
+report any missing objects or functions (ELF only).
+.TP
+.B \-\-help
+Usage information.
+.\" .SH NOTES
+.\" The standard version of
+.\" .B ldd
+.\" comes with glibc2.
+.\" Libc5 came with an older version, still present
+.\" on some systems.
+.\" The long options are not supported by the libc5 version.
+.\" On the other hand, the glibc2 version does not support
+.\" .B \-V
+.\" and only has the equivalent
+.\" .BR \-\-version .
+.\" .P
+.\" The libc5 version of this program will use the name of a library given
+.\" on the command line as-is when it contains a \[aq]/\[aq]; otherwise it
+.\" searches for the library in the standard locations.
+.\" To run it
+.\" on a shared library in the current directory, prefix the name with "./".
+.SH BUGS
+.B ldd
+does not work on a.out shared libraries.
+.P
+.B ldd
+does not work with some extremely old a.out programs which were
+built before
+.B ldd
+support was added to the compiler releases.
+If you use
+.B ldd
+on one of these programs, the program will attempt to run with
+.I argc
+= 0 and the results will be unpredictable.
+.\" .SH AUTHOR
+.\" David Engel.
+.\" Roland McGrath and Ulrich Drepper.
+.SH SEE ALSO
+.BR pldd (1),
+.BR sprof (1),
+.BR ld.so (8),
+.BR ldconfig (8)
diff --git a/man/man1/locale.1 b/man/man1/locale.1
new file mode 100644
index 000000000..8c26f831c
--- /dev/null
+++ b/man/man1/locale.1
@@ -0,0 +1,208 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH locale 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+locale \- get locale-specific information
+.SH SYNOPSIS
+.nf
+.BR locale " [\fIoption\fP]"
+.BR locale " [\fIoption\fP] " \-a
+.BR locale " [\fIoption\fP] " \-m
+.BR locale " [\fIoption\fP] \fIname\fP..."
+.fi
+.SH DESCRIPTION
+The
+.B locale
+command displays information about the current locale, or all locales,
+on standard output.
+.P
+When invoked without arguments,
+.B locale
+displays the current locale settings for each locale category (see
+.BR locale (5)),
+based on the settings of the environment variables that control the locale
+(see
+.BR locale (7)).
+Values for variables set in the environment are printed without double
+quotes, implied values are printed with double quotes.
+.P
+If either the
+.B \-a
+or the
+.B \-m
+option (or one of their long-format equivalents) is specified,
+the behavior is as follows:
+.TP
+.B \-\-all\-locales
+.TQ
+.B \-a
+Display a list of all available locales.
+The
+.B \-v
+option causes the
+.B LC_IDENTIFICATION
+metadata about each locale to be included in the output.
+.TP
+.B \-\-charmaps
+.TQ
+.B \-m
+Display the available charmaps (character set description files).
+To display the current character set for the locale, use
+\fBlocale \-c charmap\fR.
+.P
+The
+.B locale
+command can also be provided with one or more arguments,
+which are the names of locale keywords (for example,
+.IR date_fmt ,
+.IR ctype\-class\-names ,
+.IR yesexpr ,
+or
+.IR decimal_point )
+or locale categories (for example,
+.B LC_CTYPE
+or
+.BR LC_TIME ).
+For each argument, the following is displayed:
+.IP \[bu] 3
+For a locale keyword, the value of that keyword to be displayed.
+.IP \[bu]
+For a locale category,
+the values of all keywords in that category are displayed.
+.P
+When arguments are supplied, the following options are meaningful:
+.TP
+.B \-\-category\-name
+.TQ
+.B \-c
+For a category name argument,
+write the name of the locale category
+on a separate line preceding the list of keyword values for that category.
+.IP
+For a keyword name argument,
+write the name of the locale category for this keyword
+on a separate line preceding the keyword value.
+.IP
+This option improves readability when multiple name arguments are specified.
+It can be combined with the
+.B \-k
+option.
+.TP
+.B \-\-keyword\-name
+.TQ
+.B \-k
+For each keyword whose value is being displayed,
+include also the name of that keyword,
+so that the output has the format:
+.IP
+.in +4n
+.EX
+.IR keyword =\[dq] value \[dq]
+.EE
+.in
+.P
+The
+.B locale
+command also knows about the following options:
+.TP
+.B \-\-verbose
+.TQ
+.B \-v
+Display additional information for some command-line option and argument
+combinations.
+.TP
+.B \-\-help
+.TQ
+.B \-?
+Display a summary of command-line options and arguments and exit.
+.TP
+.B \-\-usage
+Display a short usage message and exit.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Display the program version and exit.
+.SH FILES
+.TP
+.I /usr/lib/locale/locale\-archive
+Usual default locale archive location.
+.TP
+.I /usr/share/i18n/locales
+Usual default path for locale definition files.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+.EX
+$ \fBlocale\fP
+LANG=en_US.UTF\-8
+LC_CTYPE="en_US.UTF\-8"
+LC_NUMERIC="en_US.UTF\-8"
+LC_TIME="en_US.UTF\-8"
+LC_COLLATE="en_US.UTF\-8"
+LC_MONETARY="en_US.UTF\-8"
+LC_MESSAGES="en_US.UTF\-8"
+LC_PAPER="en_US.UTF\-8"
+LC_NAME="en_US.UTF\-8"
+LC_ADDRESS="en_US.UTF\-8"
+LC_TELEPHONE="en_US.UTF\-8"
+LC_MEASUREMENT="en_US.UTF\-8"
+LC_IDENTIFICATION="en_US.UTF\-8"
+LC_ALL=
+.P
+$ \fBlocale date_fmt\fP
+%a %b %e %H:%M:%S %Z %Y
+.P
+$ \fBlocale \-k date_fmt\fP
+date_fmt="%a %b %e %H:%M:%S %Z %Y"
+.P
+$ \fBlocale \-ck date_fmt\fP
+LC_TIME
+date_fmt="%a %b %e %H:%M:%S %Z %Y"
+.P
+$ \fBlocale LC_TELEPHONE\fP
++%c (%a) %l
+(%a) %l
+11
+1
+UTF\-8
+.P
+$ \fBlocale \-k LC_TELEPHONE\fP
+tel_int_fmt="+%c (%a) %l"
+tel_dom_fmt="(%a) %l"
+int_select="11"
+int_prefix="1"
+telephone\-codeset="UTF\-8"
+.EE
+.P
+The following example compiles a custom locale from the
+.I ./wrk
+directory with the
+.BR localedef (1)
+utility under the
+.I $HOME/.locale
+directory, then tests the result with the
+.BR date (1)
+command, and then sets the environment variables
+.B LOCPATH
+and
+.B LANG
+in the shell profile file so that the custom locale will be used in the
+subsequent user sessions:
+.P
+.EX
+$ \fBmkdir \-p $HOME/.locale\fP
+$ \fBI18NPATH=./wrk/ localedef \-f UTF\-8 \-i fi_SE $HOME/.locale/fi_SE.UTF\-8\fP
+$ \fBLOCPATH=$HOME/.locale LC_ALL=fi_SE.UTF\-8 date\fP
+$ \fBecho "export LOCPATH=\e$HOME/.locale" >> $HOME/.bashrc\fP
+$ \fBecho "export LANG=fi_SE.UTF\-8" >> $HOME/.bashrc\fP
+.EE
+.SH SEE ALSO
+.BR localedef (1),
+.BR charmap (5),
+.BR locale (5),
+.BR locale (7)
diff --git a/man/man1/localedef.1 b/man/man1/localedef.1
new file mode 100644
index 000000000..6a7877089
--- /dev/null
+++ b/man/man1/localedef.1
@@ -0,0 +1,415 @@
+.\" Copyright (C) 2001 Richard Braakman
+.\" Copyright (C) 2004 Alastair McKinstry
+.\" Copyright (C) 2005 Lars Wirzenius
+.\" Copyright (C) 2014 Marko Myllynen
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" This manual page was initially written by Richard Braakman
+.\" on behalf of the Debian GNU/Linux Project and anyone else
+.\" who wants it. It was amended by Alastair McKinstry to
+.\" explain new ISO/IEC 14652 elements, and amended further by
+.\" Lars Wirzenius to document new functionality (as of GNU
+.\" C library 2.3.5).
+.\"
+.TH localedef 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+localedef \- compile locale definition files
+.SH SYNOPSIS
+.SY localedef
+.RI [ options ]
+.I outputpath
+.YS
+.SY localedef
+.B \-\-add\-to\-archive
+.RI [ options ]
+.I compiledpath
+.YS
+.SY localedef
+.B \-\-delete\-from\-archive
+.RI [ options ]
+.IR localename " ..."
+.YS
+.SY localedef
+.B \-\-list\-archive
+.RI [ options ]
+.YS
+.SY localedef
+.B \-\-help
+.YS
+.SY localedef
+.B \-\-usage
+.YS
+.SY localedef
+.B \-\-version
+.YS
+.SH DESCRIPTION
+The
+.B localedef
+program reads the indicated
+.I charmap
+and
+.I input
+files,
+compiles them to a binary form quickly usable by the
+locale functions in the C library
+.RB ( setlocale (3),
+.BR localeconv (3),
+etc.),
+and places the output in
+.IR outputpath .
+.P
+The
+.I outputpath
+argument is interpreted as follows:
+.IP \[bu] 3
+If
+.I outputpath
+contains a slash character ('/'),
+it is interpreted as the name of the
+directory where the output definitions are to be stored.
+In this case,
+there is a separate output file for each locale category
+.RI ( LC_TIME ,
+.IR LC_NUMERIC ,
+and so on).
+.IP \[bu]
+If the
+.B \-\-no\-archive
+option is used,
+.I outputpath
+is the name of a subdirectory in
+.I /usr/lib/locale
+where per-category compiled files are placed.
+.IP \[bu]
+Otherwise,
+.I outputpath
+is the name of a locale and the compiled locale data is added to the
+archive file
+.IR /usr/lib/locale/locale\-archive .
+A locale archive is a memory-mapped file which contains all the
+system-provided locales;
+it is used by all localized programs when the environment variable
+.B LOCPATH
+is not set.
+.P
+In any case,
+.B localedef
+aborts if the directory in which it tries to write locale files has
+not already been created.
+.P
+If no
+.I charmapfile
+is given,
+the value
+.I ANSI_X3.4\-1968
+(for ASCII) is used by default.
+If no
+.I inputfile
+is given,
+or if it is given as a dash
+(\-),
+.B localedef
+reads from standard input.
+.SH OPTIONS
+.SS Operation-selection options
+A few options direct
+.B localedef
+to do something other than compile locale definitions.
+Only one of these options should be used at a time.
+.TP
+.B \-\-add\-to\-archive
+Add the
+.I compiledpath
+directories to the locale archive file.
+The directories should have been created by previous runs of
+.BR localedef ,
+using
+.BR \-\-no\-archive .
+.TP
+.B \-\-delete\-from\-archive
+Delete the named locales from the locale archive file.
+.TP
+.B \-\-list\-archive
+List the locales contained in the locale archive file.
+.SS Other options
+Some of the following options are sensible only for certain operations;
+generally,
+it should be self-evident which ones.
+Notice that
+.B \-f
+and
+.B \-c
+are reversed from what you might expect;
+that is,
+.B \-f
+is not the same as
+.BR \-\-force .
+.TP
+.BI \-f " charmapfile" "\fR, \fP\-\-charmap=" charmapfile
+Specify the file that defines the character set
+that is used by the input file.
+If
+.I charmapfile
+contains a slash character ('/'),
+it is interpreted as the name of the character map.
+Otherwise,
+the file is sought in the current directory
+and the default directory for character maps.
+If the environment variable
+.B I18NPATH
+is set,
+.I $I18NPATH/charmaps/
+and
+.I $I18NPATH/
+are also searched after the current directory.
+The default directory for character maps is printed by
+.BR "localedef \-\-help" .
+.TP
+.BI \-i " inputfile" "\fR, \fP\-\-inputfile=" inputfile
+Specify the locale definition file to compile.
+The file is sought in the current directory
+and the default directory for locale definition files.
+If the environment variable
+.B I18NPATH
+is set,
+.I $I18NPATH/locales/
+and
+.I $I18NPATH
+are also searched after the current directory.
+The default directory for locale definition files is printed by
+.BR "localedef \-\-help" .
+.TP
+.BI \-u " repertoirefile" "\fR, \fP\-\-repertoire\-map=" repertoirefile
+Read mappings from symbolic names to Unicode code points from
+.IR repertoirefile .
+If
+.I repertoirefile
+contains a slash character ('/'),
+it is interpreted as the pathname of the repertoire map.
+Otherwise,
+the file is sought in the current directory
+and the default directory for repertoire maps.
+If the environment variable
+.B I18NPATH
+is set,
+.I $I18NPATH/repertoiremaps/
+and
+.I $I18NPATH
+are also searched after the current directory.
+The default directory for repertoire maps is printed by
+.BR "localedef \-\-help" .
+.TP
+.BI \-A " aliasfile" "\fR, \fP\-\-alias\-file=" aliasfile
+Use
+.I aliasfile
+to look up aliases for locale names.
+There is no default aliases file.
+.TP
+.B \-\-force
+.TQ
+.B \-c
+Write the output files even if warnings were generated about the input
+file.
+.TP
+.B \-\-verbose
+.TQ
+.B \-v
+Generate extra warnings about errors that are normally ignored.
+.TP
+.B \-\-big\-endian
+Generate big-endian output.
+.TP
+.B \-\-little\-endian
+Generate little-endian output.
+.TP
+.B \-\-no\-archive
+Do not use the locale archive file,
+instead create
+.I outputpath
+as a subdirectory in the same directory as the locale archive file,
+and create separate output files for locale categories in it.
+This is helpful to prevent system locale archive updates from overwriting
+custom locales created with
+.BR localedef .
+.TP
+.B \-\-no\-hard\-links
+Do not create hard links between installed locales.
+.TP
+.BI \-\-no\-warnings= warnings
+Comma-separated list of warnings to disable.
+Supported warnings are
+.I ascii
+and
+.IR intcurrsym .
+.TP
+.B \-\-posix
+Conform strictly to POSIX.
+Implies
+.BR \-\-verbose .
+This option currently has no other effect.
+POSIX conformance is assumed if the environment variable
+.B POSIXLY_CORRECT
+is set.
+.TP
+.BI \-\-prefix= pathname
+Set the prefix to be prepended to the full archive pathname.
+By default,
+the prefix is empty.
+Setting the prefix to
+.IR foo ,
+the archive would be placed in
+.IR foo/usr/lib/locale/locale\-archive .
+.TP
+.B \-\-quiet
+Suppress all notifications and warnings,
+and report only fatal errors.
+.TP
+.B \-\-replace
+Replace a locale in the locale archive file.
+Without this option,
+if the locale is in the archive file already,
+an error occurs.
+.TP
+.BI \-\-warnings= warnings
+Comma-separated list of warnings to enable.
+Supported warnings are
+.I ascii
+and
+.IR intcurrsym .
+.TP
+.B \-\-help
+.TQ
+.B \-?
+Print a usage summary and exit.
+Also prints the default paths used by
+.BR localedef .
+.TP
+.B \-\-usage
+Print a short usage summary and exit.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Print the version number,
+license,
+and disclaimer of warranty for
+.BR localedef .
+.SH EXIT STATUS
+One of the following exit values can be returned by
+.BR localedef :
+.TP
+.B 0
+Command completed successfully.
+.TP
+.B 1
+Warnings or errors occurred,
+output files were written.
+.TP
+.B 4
+Errors encountered,
+no output created.
+.SH ENVIRONMENT
+.TP
+.B POSIXLY_CORRECT
+The
+.B \-\-posix
+flag is assumed if this environment variable is set.
+.TP
+.B I18NPATH
+A colon-separated list of search directories for files.
+.SH FILES
+.TP
+.I /usr/share/i18n/charmaps
+Usual default character map path.
+.TP
+.I /usr/share/i18n/locales
+Usual default path for locale definition files.
+.TP
+.I /usr/share/i18n/repertoiremaps
+Usual default repertoire map path.
+.TP
+.I /usr/lib/locale/locale\-archive
+Usual default locale archive location.
+.TP
+.I /usr/lib/locale
+Usual default path for compiled individual locale data files.
+.TP
+.I outputpath/LC_ADDRESS
+An output file that contains information about formatting of
+addresses and geography-related items.
+.TP
+.I outputpath/LC_COLLATE
+An output file that contains information about the rules for comparing
+strings.
+.TP
+.I outputpath/LC_CTYPE
+An output file that contains information about character classes.
+.TP
+.I outputpath/LC_IDENTIFICATION
+An output file that contains metadata about the locale.
+.TP
+.I outputpath/LC_MEASUREMENT
+An output file that contains information about locale measurements
+(metric versus US customary).
+.TP
+.I outputpath/LC_MESSAGES/SYS_LC_MESSAGES
+An output file that contains information about the language messages
+should be printed in,
+and what an affirmative or negative answer looks like.
+.TP
+.I outputpath/LC_MONETARY
+An output file that contains information about formatting of monetary
+values.
+.TP
+.I outputpath/LC_NAME
+An output file that contains information about salutations for persons.
+.TP
+.I outputpath/LC_NUMERIC
+An output file that contains information about formatting of nonmonetary
+numeric values.
+.TP
+.I outputpath/LC_PAPER
+An output file that contains information about settings related to
+standard paper size.
+.TP
+.I outputpath/LC_TELEPHONE
+An output file that contains information about formats to be used with
+telephone services.
+.TP
+.I outputpath/LC_TIME
+An output file that contains information about formatting of data and
+time values.
+.SH STANDARDS
+POSIX.1-2008.
+.SH EXAMPLES
+Compile the locale files for Finnish in the UTF\-8 character set
+and add it to the default locale archive with the name
+.BR fi_FI.UTF\-8 :
+.P
+.in +4n
+.EX
+localedef \-f UTF\-8 \-i fi_FI fi_FI.UTF\-8
+.EE
+.in
+.P
+The next example does the same thing,
+but generates files into the
+.I fi_FI.UTF\-8
+directory which can then be used by programs when the environment
+variable
+.B LOCPATH
+is set to the current directory (note that the last argument must
+contain a slash):
+.P
+.in +4n
+.EX
+localedef \-f UTF\-8 \-i fi_FI ./fi_FI.UTF\-8
+.EE
+.in
+.SH SEE ALSO
+.BR locale (1),
+.BR charmap (5),
+.BR locale (5),
+.BR repertoiremap (5),
+.BR locale (7)
diff --git a/man/man1/memusage.1 b/man/man1/memusage.1
new file mode 100644
index 000000000..b6793f6e8
--- /dev/null
+++ b/man/man1/memusage.1
@@ -0,0 +1,262 @@
+.\" Copyright (c) 2013, Peter Schiffer <pschiffe@redhat.com>
+.\" and Copyright (C) 2014, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH memusage 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memusage \- profile memory usage of a program
+.SH SYNOPSIS
+.nf
+.BR memusage " [\fIoption\fR]... \fIprogram\fR [\fIprogramoption\fR]..."
+.fi
+.SH DESCRIPTION
+.B memusage
+is a bash script which profiles memory usage of the program,
+.IR program .
+It preloads the
+.B libmemusage.so
+library into the caller's environment (via the
+.B LD_PRELOAD
+environment variable; see
+.BR ld.so (8)).
+The
+.B libmemusage.so
+library traces memory allocation by intercepting calls to
+.BR malloc (3),
+.BR calloc (3),
+.BR free (3),
+and
+.BR realloc (3);
+optionally, calls to
+.BR mmap (2),
+.BR mremap (2),
+and
+.BR munmap (2)
+can also be intercepted.
+.P
+.B memusage
+can output the collected data in textual form, or it can use
+.BR memusagestat (1)
+(see the
+.B \-p
+option,  below)
+to create a PNG file containing graphical representation
+of the collected data.
+.SS Memory usage summary
+The "Memory usage summary" line output by
+.B memusage
+contains three fields:
+.RS 4
+.TP
+\fBheap total\fR
+Sum of \fIsize\fR arguments of all
+.BR malloc (3)
+calls,
+products of arguments (\fInmemb\fR*\fIsize\fR) of all
+.BR calloc (3)
+calls,
+and sum of \fIlength\fR arguments of all
+.BR mmap (2)
+calls.
+In the case of
+.BR realloc (3)
+and
+.BR mremap (2),
+if the new size of an allocation is larger than the previous size,
+the sum of all such differences (new size minus old size) is added.
+.TP
+.B "heap peak"
+Maximum of all \fIsize\fR arguments of
+.BR malloc (3),
+all products of \fInmemb\fR*\fIsize\fR of
+.BR calloc (3),
+all \fIsize\fR arguments of
+.BR realloc (3),
+.I length
+arguments of
+.BR mmap (2),
+and
+\fInew_size\fR arguments of
+.BR mremap (2).
+.TP
+.B "stack peak"
+Before the first call to any monitored function,
+the stack pointer address (base stack pointer) is saved.
+After each function call, the actual stack pointer address is read and
+the difference from the base stack pointer computed.
+The maximum of these differences is then the stack peak.
+.RE
+.P
+Immediately following this summary line, a table shows the number calls,
+total memory allocated or deallocated,
+and number of failed calls for each intercepted function.
+For
+.BR realloc (3)
+and
+.BR mremap (2),
+the additional field "nomove" shows reallocations that
+changed the address of a block,
+and the additional "dec" field shows reallocations that
+decreased the size of the block.
+For
+.BR realloc (3),
+the additional field "free" shows reallocations that
+caused a block to be freed (i.e., the reallocated size was 0).
+.P
+The "realloc/total memory" of the table output by
+.B memusage
+does not reflect cases where
+.BR realloc (3)
+is used to reallocate a block of memory
+to have a smaller size than previously.
+This can cause sum of all "total memory" cells (excluding "free")
+to be larger than the "free/total memory" cell.
+.SS Histogram for block sizes
+The "Histogram for block sizes" provides a breakdown of memory
+allocations into various bucket sizes.
+.SH OPTIONS
+.TP
+.BI \-n\  name \fR,\ \fB\-\-progname= name
+Name of the program file to profile.
+.TP
+.BI \-p\  file \fR,\ \fB\-\-png= file
+Generate PNG graphic and store it in
+.IR file .
+.TP
+.BI \-d\  file \fR,\ \fB\-\-data= file
+Generate binary data file and store it in
+.IR file .
+.TP
+.B \-u\fR,\ \fB\-\-unbuffered
+Do not buffer output.
+.TP
+.BI \-b\  size \fR,\ \fB\-\-buffer= size
+Collect
+.I size
+entries before writing them out.
+.TP
+.B \-\-no\-timer
+Disable timer-based
+.RB ( SIGPROF )
+sampling of stack pointer value.
+.TP
+.B \-m\fR,\ \fB\-\-mmap
+Also trace
+.BR mmap (2),
+.BR mremap (2),
+and
+.BR munmap (2).
+.TP
+.B \-?\fR,\ \fB\-\-help
+Print help and exit.
+.TP
+.B \-\-usage
+Print a short usage message and exit.
+.TP
+.B \-V\fR,\ \fB\-\-version
+Print version information and exit.
+.TP
+The following options apply only when generating graphical output:
+.TP
+.B \-t\fR,\ \fB\-\-time\-based
+Use time (rather than number of function calls) as the scale for the X axis.
+.TP
+.B \-T\fR,\ \fB\-\-total
+Also draw a graph of total memory use.
+.TP
+.BI \fB\-\-title= name
+Use
+.I name
+as the title of the graph.
+.TP
+.BI \-x\  size \fR,\ \fB\-\-x\-size= size
+Make the graph
+.I size
+pixels wide.
+.TP
+.BI \-y\  size \fR,\ \fB\-\-y\-size= size
+Make the graph
+.I size
+pixels high.
+.SH EXIT STATUS
+The exit status of
+.B memusage
+is equal to the exit status of the profiled program.
+.SH BUGS
+To report bugs, see
+.UR http://www.gnu.org/software/libc/bugs.html
+.UE
+.SH EXAMPLES
+Below is a simple program that reallocates a block of
+memory in cycles that rise to a peak before then cyclically
+reallocating the memory in smaller blocks that return to zero.
+After compiling the program and running the following commands,
+a graph of the memory usage of the program can be found in the file
+.IR memusage.png :
+.P
+.in +4n
+.EX
+$ \fBmemusage \-\-data=memusage.dat ./a.out\fP
+\&...
+Memory usage summary: heap total: 45200, heap peak: 6440, stack peak: 224
+        total calls  total memory  failed calls
+ malloc|         1           400             0
+realloc|        40         44800             0  (nomove:40, dec:19, free:0)
+ calloc|         0             0             0
+   free|         1           440
+Histogram for block sizes:
+  192\-207             1   2% ================
+\&...
+ 2192\-2207            1   2% ================
+ 2240\-2255            2   4% =================================
+ 2832\-2847            2   4% =================================
+ 3440\-3455            2   4% =================================
+ 4032\-4047            2   4% =================================
+ 4640\-4655            2   4% =================================
+ 5232\-5247            2   4% =================================
+ 5840\-5855            2   4% =================================
+ 6432\-6447            1   2% ================
+$ \fBmemusagestat memusage.dat memusage.png\fP
+.EE
+.in
+.SS Program source
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#define CYCLES 20
+\&
+int
+main(int argc, char *argv[])
+{
+    int i, j;
+    size_t size;
+    int *p;
+\&
+    size = sizeof(*p) * 100;
+    printf("malloc: %zu\en", size);
+    p = malloc(size);
+\&
+    for (i = 0; i < CYCLES; i++) {
+        if (i < CYCLES / 2)
+            j = i;
+        else
+            j\-\-;
+\&
+        size = sizeof(*p) * (j * 50 + 110);
+        printf("realloc: %zu\en", size);
+        p = realloc(p, size);
+\&
+        size = sizeof(*p) * ((j + 1) * 150 + 110);
+        printf("realloc: %zu\en", size);
+        p = realloc(p, size);
+    }
+\&
+    free(p);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR memusagestat (1),
+.BR mtrace (1),
+.BR ld.so (8)
diff --git a/man/man1/memusagestat.1 b/man/man1/memusagestat.1
new file mode 100644
index 000000000..4825ca67f
--- /dev/null
+++ b/man/man1/memusagestat.1
@@ -0,0 +1,73 @@
+.\" Copyright (c) 2013, Peter Schiffer <pschiffe@redhat.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH memusagestat 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memusagestat \- generate graphic from memory profiling data
+.SH SYNOPSIS
+.nf
+.BR memusagestat " [\fIoption\fR]... \fIdatafile\fR [\fIoutfile\fR]"
+.fi
+.SH DESCRIPTION
+.B memusagestat
+creates a PNG file containing a graphical representation of the
+memory profiling data in the file
+.IR datafile ;
+that file is generated via the
+.I \-d
+(or
+.IR \-\-data )
+option of
+.BR memusage (1).
+.P
+The red line in the graph shows the heap usage (allocated memory)
+and the green line shows the stack usage.
+The x-scale is either the number of memory-handling function calls or
+(if the
+.I \-t
+option is specified)
+time.
+.SH OPTIONS
+.TP
+.BI \-o\  file \fR,\ \fB\-\-output= file
+Name of the output file.
+.TP
+.BI \-s\  string \fR,\ \fB\-\-string= string
+Use
+.I string
+as the title inside the output graph.
+.TP
+.B \-t\fR,\ \fB\-\-time
+Use time (rather than number of function calls) as the scale for the X axis.
+.TP
+.B \-T\fR,\ \fB\-\-total
+Also draw a graph of total memory consumption.
+.TP
+.BI \-x\  size \fR,\ \fB\-\-x\-size= size
+Make the output graph
+.I size
+pixels wide.
+.TP
+.BI \-y\  size \fR,\ \fB\-\-y\-size= size
+Make the output graph
+.I size
+pixels high.
+.TP
+.B \-?\fR,\ \fB\-\-help
+Print a help message and exit.
+.TP
+.B \-\-usage
+Print a short usage message and exit.
+.TP
+.B \-V\fR,\ \fB\-\-version
+Print version information and exit.
+.SH BUGS
+To report bugs, see
+.UR http://www.gnu.org/software/libc/bugs.html
+.UE
+.SH EXAMPLES
+See
+.BR memusage (1).
+.SH SEE ALSO
+.BR memusage (1),
+.BR mtrace (1)
diff --git a/man/man1/mtrace.1 b/man/man1/mtrace.1
new file mode 100644
index 000000000..7b802837a
--- /dev/null
+++ b/man/man1/mtrace.1
@@ -0,0 +1,47 @@
+.\" Copyright (c) 2013, Peter Schiffer (pschiffe@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH mtrace 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mtrace \- interpret the malloc trace log
+.SH SYNOPSIS
+.nf
+.BR mtrace " [\fIoption\fR]... [\fIbinary\fR] \fImtracedata\fR"
+.fi
+.SH DESCRIPTION
+.B mtrace
+is a Perl script used to interpret and provide human readable output
+of the trace log contained in the file
+.IR mtracedata ,
+whose contents were produced by
+.BR mtrace (3).
+If
+.I binary
+is provided, the output of
+.B mtrace
+also contains the source file name with line number information
+for problem locations
+(assuming that
+.I binary
+was compiled with debugging information).
+.P
+For more information about the
+.BR mtrace (3)
+function and
+.B mtrace
+script usage, see
+.BR mtrace (3).
+.SH OPTIONS
+.TP
+.B \-\-help
+Print help and exit.
+.TP
+.B \-\-version
+Print version information and exit.
+.SH BUGS
+For bug reporting instructions, please see:
+.UR http://www.gnu.org/software/libc/bugs.html
+.UE .
+.SH SEE ALSO
+.BR memusage (1),
+.BR mtrace (3)
diff --git a/man/man1/pldd.1 b/man/man1/pldd.1
new file mode 100644
index 000000000..e0fa32b6e
--- /dev/null
+++ b/man/man1/pldd.1
@@ -0,0 +1,105 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pldd 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pldd \- display dynamic shared objects linked into a process
+.SH SYNOPSIS
+.nf
+.BI "pldd " "pid"
+.BI pldd " option"
+.fi
+.SH DESCRIPTION
+The
+.B pldd
+command displays a list of the dynamic shared objects (DSOs) that are
+linked into the process with the specified process ID (PID).
+The list includes the libraries that have been dynamically loaded using
+.BR dlopen (3).
+.SH OPTIONS
+.TP
+.B \-\-help
+.TQ
+.B \-?
+Display a help message and exit.
+.TP
+.B \-\-usage
+Display a short usage message and exit.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Display program version information and exit.
+.SH EXIT STATUS
+On success,
+.B pldd
+exits with the status 0.
+If the specified process does not exist,
+the user does not have permission to access
+its dynamic shared object list,
+or no command-line arguments are supplied,
+.B pldd
+exists with a status of 1.
+If given an invalid option, it exits with the status 64.
+.SH VERSIONS
+Some other systems
+.\" There are man pages on Solaris and HP-UX.
+have a similar command.
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.15.
+.SH NOTES
+The command
+.P
+.in +4n
+.EX
+lsof \-p PID
+.EE
+.in
+.P
+also shows output that includes the dynamic shared objects
+that are linked into a process.
+.P
+The
+.BR gdb (1)
+.I "info shared"
+command also shows the shared libraries being used by a process,
+so that one can obtain similar output to
+.B pldd
+using a command such as the following
+(to monitor the process with the specified
+.IR pid ):
+.P
+.in +4n
+.EX
+$ \fBgdb \-ex "set confirm off" \-ex "set height 0" \-ex "info shared" \e\fP
+        \fB\-ex "quit" \-p $pid | grep \[aq]\[ha]0x.*0x\[aq]\fP
+.EE
+.in
+.SH BUGS
+From glibc 2.19 to glibc 2.29,
+.B pldd
+was broken: it just hung when executed.
+.\" glibc commit 1a4c27355e146b6d8cc6487b998462c7fdd1048f
+This problem was fixed in glibc 2.30, and the fix has been backported
+to earlier glibc versions in some distributions.
+.SH EXAMPLES
+.EX
+$ \fBecho $$\fP               # Display PID of shell
+1143
+$ \fBpldd $$\fP               # Display DSOs linked into the shell
+1143:   /usr/bin/bash
+linux\-vdso.so.1
+/lib64/libtinfo.so.5
+/lib64/libdl.so.2
+/lib64/libc.so.6
+/lib64/ld\-linux\-x86\-64.so.2
+/lib64/libnss_files.so.2
+.EE
+.SH SEE ALSO
+.BR ldd (1),
+.BR lsof (1),
+.BR dlopen (3),
+.BR ld.so (8)
diff --git a/man/man1/sprof.1 b/man/man1/sprof.1
new file mode 100644
index 000000000..a6eb7ad3c
--- /dev/null
+++ b/man/man1/sprof.1
@@ -0,0 +1,282 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sprof 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sprof \- read and display shared object profiling data
+.SH SYNOPSIS
+.nf
+.BR sprof " [\fIoption\fP]... \fIshared-object-path\fP \
+[\fIprofile-data-path\fP]"
+.fi
+.SH DESCRIPTION
+The
+.B sprof
+command displays a profiling summary for the
+shared object (shared library) specified as its first command-line argument.
+The profiling summary is created using previously generated
+profiling data in the (optional) second command-line argument.
+If the profiling data pathname is omitted, then
+.B sprof
+will attempt to deduce it using the soname of the shared object,
+looking for a file with the name
+.I <soname>.profile
+in the current directory.
+.SH OPTIONS
+The following command-line options specify the profile output
+to be produced:
+.TP
+.B \-\-call\-pairs
+.TQ
+.B \-c
+Print a list of pairs of call paths for the interfaces exported
+by the shared object,
+along with the number of times each path is used.
+.TP
+.B \-\-flat\-profile
+.TQ
+.B \-p
+Generate a flat profile of all of the functions in the monitored object,
+with counts and ticks.
+.TP
+.B \-\-graph
+.TQ
+.B \-q
+Generate a call graph.
+.P
+If none of the above options is specified,
+then the default behavior is to display a flat profile and a call graph.
+.P
+The following additional command-line options are available:
+.TP
+.B \-\-help
+.TQ
+.B \-?
+Display a summary of command-line options and arguments and exit.
+.TP
+.B \-\-usage
+Display a short usage message and exit.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Display the program version and exit.
+.SH STANDARDS
+GNU.
+.SH EXAMPLES
+The following example demonstrates the use of
+.BR sprof .
+The example consists of a main program that calls two functions
+in a shared object.
+First, the code of the main program:
+.P
+.in +4n
+.EX
+$ \fBcat prog.c\fP
+#include <stdlib.h>
+\&
+void x1(void);
+void x2(void);
+\&
+int
+main(int argc, char *argv[])
+{
+    x1();
+    x2();
+    exit(EXIT_SUCCESS);
+}
+.EE
+.in
+.P
+The functions
+.IR x1 ()
+and
+.IR x2 ()
+are defined in the following source file that is used to
+construct the shared object:
+.P
+.in +4n
+.EX
+$ \fBcat libdemo.c\fP
+#include <unistd.h>
+\&
+void
+consumeCpu1(int lim)
+{
+    for (unsigned int j = 0; j < lim; j++)
+	getppid();
+}
+\&
+void
+x1(void) {
+    for (unsigned int j = 0; j < 100; j++)
+	consumeCpu1(200000);
+}
+\&
+void
+consumeCpu2(int lim)
+{
+    for (unsigned int j = 0; j < lim; j++)
+	getppid();
+}
+\&
+void
+x2(void)
+{
+    for (unsigned int j = 0; j < 1000; j++)
+	consumeCpu2(10000);
+}
+.EE
+.in
+.P
+Now we construct the shared object with the real name
+.IR libdemo.so.1.0.1 ,
+and the soname
+.IR libdemo.so.1 :
+.P
+.in +4n
+.EX
+$ \fBcc \-g \-fPIC \-shared \-Wl,\-soname,libdemo.so.1 \e\fP
+        \fB\-o libdemo.so.1.0.1 libdemo.c\fP
+.EE
+.in
+.P
+Then we construct symbolic links for the library soname and
+the library linker name:
+.P
+.in +4n
+.EX
+$ \fBln \-sf libdemo.so.1.0.1 libdemo.so.1\fP
+$ \fBln \-sf libdemo.so.1 libdemo.so\fP
+.EE
+.in
+.P
+Next, we compile the main program, linking it against the shared object,
+and then list the dynamic dependencies of the program:
+.P
+.in +4n
+.EX
+$ \fBcc \-g \-o prog prog.c \-L. \-ldemo\fP
+$ \fBldd prog\fP
+	linux\-vdso.so.1 =>  (0x00007fff86d66000)
+	libdemo.so.1 => not found
+	libc.so.6 => /lib64/libc.so.6 (0x00007fd4dc138000)
+	/lib64/ld\-linux\-x86\-64.so.2 (0x00007fd4dc51f000)
+.EE
+.in
+.P
+In order to get profiling information for the shared object,
+we define the environment variable
+.B LD_PROFILE
+with the soname of the library:
+.P
+.in +4n
+.EX
+$ \fBexport LD_PROFILE=libdemo.so.1\fP
+.EE
+.in
+.P
+We then define the environment variable
+.B LD_PROFILE_OUTPUT
+with the pathname of the directory where profile output should be written,
+and create that directory if it does not exist already:
+.P
+.in +4n
+.EX
+$ \fBexport LD_PROFILE_OUTPUT=$(pwd)/prof_data\fP
+$ \fBmkdir \-p $LD_PROFILE_OUTPUT\fP
+.EE
+.in
+.P
+.B LD_PROFILE
+causes profiling output to be
+.I appended
+to the output file if it already exists,
+so we ensure that there is no preexisting profiling data:
+.P
+.in +4n
+.EX
+$ \fBrm \-f $LD_PROFILE_OUTPUT/$LD_PROFILE.profile\fP
+.EE
+.in
+.P
+We then run the program to produce the profiling output,
+which is written to a file in the directory specified in
+.BR LD_PROFILE_OUTPUT :
+.P
+.in +4n
+.EX
+$ \fBLD_LIBRARY_PATH=. ./prog\fP
+$ \fBls prof_data\fP
+libdemo.so.1.profile
+.EE
+.in
+.P
+We then use the
+.B sprof \-p
+option to generate a flat profile with counts and ticks:
+.P
+.in +4n
+.EX
+$ \fBsprof \-p libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
+Flat profile:
+\&
+Each sample counts as 0.01 seconds.
+  %   cumulative   self              self     total
+ time   seconds   seconds    calls  us/call  us/call  name
+ 60.00      0.06     0.06      100   600.00           consumeCpu1
+ 40.00      0.10     0.04     1000    40.00           consumeCpu2
+  0.00      0.10     0.00        1     0.00           x1
+  0.00      0.10     0.00        1     0.00           x2
+.EE
+.in
+.P
+The
+.B sprof \-q
+option generates a call graph:
+.P
+.in +4n
+.EX
+$ \fBsprof \-q libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
+\&
+index % time    self  children    called     name
+\&
+                0.00    0.00      100/100         x1 [1]
+[0]    100.0    0.00    0.00      100         consumeCpu1 [0]
+\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
+                0.00    0.00        1/1           <UNKNOWN>
+[1]      0.0    0.00    0.00        1         x1 [1]
+                0.00    0.00      100/100         consumeCpu1 [0]
+\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
+                0.00    0.00     1000/1000        x2 [3]
+[2]      0.0    0.00    0.00     1000         consumeCpu2 [2]
+\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
+                0.00    0.00        1/1           <UNKNOWN>
+[3]      0.0    0.00    0.00        1         x2 [3]
+                0.00    0.00     1000/1000        consumeCpu2 [2]
+\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
+.EE
+.in
+.P
+Above and below, the "<UNKNOWN>" strings represent identifiers that
+are outside of the profiled object (in this example, these are instances of
+.IR main() ).
+.P
+The
+.B sprof \-c
+option generates a list of call pairs and the number of their occurrences:
+.P
+.in +4n
+.EX
+$ \fBsprof \-c libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
+<UNKNOWN>                  x1                                 1
+x1                         consumeCpu1                      100
+<UNKNOWN>                  x2                                 1
+x2                         consumeCpu2                     1000
+.EE
+.in
+.SH SEE ALSO
+.BR gprof (1),
+.BR ldd (1),
+.BR ld.so (8)
diff --git a/man/man1/time.1 b/man/man1/time.1
new file mode 100644
index 000000000..9b7efcfd4
--- /dev/null
+++ b/man/man1/time.1
@@ -0,0 +1,329 @@
+.\" Copyright Andries Brouwer, 2000
+.\" Some fragments of text came from the time-1.7 info file.
+.\" Inspired by kromJx@crosswinds.net.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH time 1 (date) "Linux man-pages (unreleased)"
+.SH NAME
+time \- time a simple command or give resource usage
+.SH SYNOPSIS
+.B time
+.RI [ option \~.\|.\|.\&] " command " [ argument \~.\|.\|.]
+.SH DESCRIPTION
+The
+.B time
+command runs the specified program
+.I command
+with the given arguments.
+When
+.I command
+finishes,
+.B time
+writes a message to standard error giving timing statistics
+about this program run.
+These statistics consist of (i) the elapsed real time
+between invocation and termination, (ii) the user CPU time
+(the sum of the
+.I tms_utime
+and
+.I tms_cutime
+values in a
+.I "struct tms"
+as returned by
+.BR times (2)),
+and (iii) the system CPU time (the sum of the
+.I  tms_stime
+and
+.I tms_cstime
+values in a
+.I "struct tms"
+as returned by
+.BR times (2)).
+.P
+Note: some shells (e.g.,
+.BR bash (1))
+have a built-in
+.B time
+command that provides similar information on the usage of time and
+possibly other resources.
+To access the real command, you may need to specify its pathname
+(something like
+.IR /usr/bin/time ).
+.SH OPTIONS
+.TP
+.B \-p
+When in the POSIX locale, use the precise traditional format
+.IP
+.in +4n
+.EX
+"real %f\enuser %f\ensys %f\en"
+.EE
+.in
+.IP
+(with numbers in seconds)
+where the number of decimals in the output for %f is unspecified
+but is sufficient to express the clock tick accuracy, and at least one.
+.SH EXIT STATUS
+If
+.I command
+was invoked, the exit status is that of
+.IR command .
+Otherwise, it is 127 if
+.I command
+could not be found, 126 if it could be found but could not be invoked,
+and some other nonzero value (1\[en]125) if something else went wrong.
+.SH ENVIRONMENT
+The variables
+.BR LANG ,
+.BR LC_ALL ,
+.BR LC_CTYPE ,
+.BR LC_MESSAGES ,
+.BR LC_NUMERIC ,
+and
+.B NLSPATH
+are used for the text and formatting of the output.
+.B PATH
+is used to search for
+.IR command .
+.SH GNU VERSION
+Below a description of the GNU 1.7 version of
+.BR time .
+Disregarding the name of the utility, GNU makes it output lots of
+useful information, not only about time used, but also on other
+resources like memory, I/O and IPC calls (where available).
+The output is formatted using a format string that can be specified
+using the
+.I \-f
+option or the
+.B TIME
+environment variable.
+.P
+The default format string is:
+.P
+.in +4n
+.EX
+%Uuser %Ssystem %Eelapsed %PCPU (%Xtext+%Ddata %Mmax)k
+%Iinputs+%Ooutputs (%Fmajor+%Rminor)pagefaults %Wswaps
+.EE
+.in
+.P
+When the
+.I \-p
+option is given, the (portable) output format is used:
+.P
+.in +4n
+.EX
+real %e
+user %U
+sys %S
+.EE
+.in
+.\"
+.SS The format string
+The format is interpreted in the usual printf-like way.
+Ordinary characters are directly copied, tab, newline,
+and backslash are escaped using \et, \en, and \e\e,
+a percent sign is represented by %%, and otherwise %
+indicates a conversion.
+The program
+.B time
+will always add a trailing newline itself.
+The conversions follow.
+All of those used by
+.BR tcsh (1)
+are supported.
+.P
+.B "Time"
+.TP
+.B %E
+Elapsed real time (in [hours:]minutes:seconds).
+.TP
+.B %e
+(Not in
+.BR tcsh (1).)
+Elapsed real time (in seconds).
+.TP
+.B %S
+Total number of CPU-seconds that the process spent in kernel mode.
+.TP
+.B %U
+Total number of CPU-seconds that the process spent in user mode.
+.TP
+.B %P
+Percentage of the CPU that this job got, computed as (%U + %S) / %E.
+.P
+.B "Memory"
+.TP
+.B %M
+Maximum resident set size of the process during its lifetime, in Kbytes.
+.TP
+.B %t
+(Not in
+.BR tcsh (1).)
+Average resident set size of the process, in Kbytes.
+.TP
+.B %K
+Average total (data+stack+text) memory use of the process,
+in Kbytes.
+.TP
+.B %D
+Average size of the process's unshared data area, in Kbytes.
+.TP
+.B %p
+(Not in
+.BR tcsh (1).)
+Average size of the process's unshared stack space, in Kbytes.
+.TP
+.B %X
+Average size of the process's shared text space, in Kbytes.
+.TP
+.B %Z
+(Not in
+.BR tcsh (1).)
+System's page size, in bytes.
+This is a per-system constant, but varies between systems.
+.TP
+.B %F
+Number of major page faults that occurred while the process was running.
+These are faults where the page has to be read in from disk.
+.TP
+.B %R
+Number of minor, or recoverable, page faults.
+These are faults for pages that are not valid but which have
+not yet been claimed by other virtual pages.
+Thus the data
+in the page is still valid but the system tables must be updated.
+.TP
+.B %W
+Number of times the process was swapped out of main memory.
+.TP
+.B %c
+Number of times the process was context-switched involuntarily
+(because the time slice expired).
+.TP
+.B %w
+Number of waits: times that the program was context-switched voluntarily,
+for instance while waiting for an I/O operation to complete.
+.P
+.B "I/O"
+.TP
+.B %I
+Number of filesystem inputs by the process.
+.TP
+.B %O
+Number of filesystem outputs by the process.
+.TP
+.B %r
+Number of socket messages received by the process.
+.TP
+.B %s
+Number of socket messages sent by the process.
+.TP
+.B %k
+Number of signals delivered to the process.
+.TP
+.B %C
+(Not in
+.BR tcsh (1).)
+Name and command-line arguments of the command being timed.
+.TP
+.B %x
+(Not in
+.BR tcsh (1).)
+Exit status of the command.
+.SS GNU options
+.TP
+.BI "\-f " format ", \-\-format=" format
+Specify output format, possibly overriding the format specified
+in the environment variable TIME.
+.TP
+.B "\-p, \-\-portability"
+Use the portable output format.
+.TP
+.BI "\-o " file ", \-\-output=" file
+Do not send the results to
+.IR stderr ,
+but overwrite the specified file.
+.TP
+.B "\-a, \-\-append"
+(Used together with \-o.) Do not overwrite but append.
+.TP
+.B "\-v, \-\-verbose"
+Give very verbose output about all the program knows about.
+.TP
+.B "\-q, \-\-quiet"
+Don't report abnormal program termination (where
+.I command
+is terminated by a signal) or nonzero exit status.
+.\"
+.SS GNU standard options
+.TP
+.B "\-\-help"
+Print a usage message on standard output and exit successfully.
+.TP
+.B "\-V, \-\-version"
+Print version information on standard output, then exit successfully.
+.TP
+.B "\-\-"
+Terminate option list.
+.SH BUGS
+Not all resources are measured by all versions of UNIX,
+so some of the values might be reported as zero.
+The present selection was mostly inspired by the data
+provided by 4.2 or 4.3BSD.
+.P
+GNU time version 1.7 is not yet localized.
+Thus, it does not implement the POSIX requirements.
+.P
+The environment variable
+.B TIME
+was badly chosen.
+It is not unusual for systems like
+.BR autoconf (1)
+or
+.BR make (1)
+to use environment variables with the name of a utility to override
+the utility to be used.
+Uses like MORE or TIME for options to programs
+(instead of program pathnames) tend to lead to difficulties.
+.P
+It seems unfortunate that
+.I \-o
+overwrites instead of appends.
+(That is, the
+.I \-a
+option should be the default.)
+.P
+Mail suggestions and bug reports for GNU
+.B time
+to
+.IR bug\-time@gnu.org .
+Please include the version of
+.BR time ,
+which you can get by running
+.P
+.in +4n
+.EX
+time \-\-version
+.EE
+.in
+.P
+and the operating system
+and C compiler you used.
+.\" .SH AUTHORS
+.\" .TP
+.\" .IP "David Keppel"
+.\" Original version
+.\" .IP "David MacKenzie"
+.\" POSIXization, autoconfiscation, GNU getoptization,
+.\" documentation, other bug fixes and improvements.
+.\" .IP "Arne Henrik Juul"
+.\" Helped with portability
+.\" .IP "Francois Pinard"
+.\" Helped with portability
+.SH SEE ALSO
+.BR bash (1),
+.BR tcsh (1),
+.BR times (2),
+.BR wait3 (2)
diff --git a/man/man2/_Exit.2 b/man/man2/_Exit.2
new file mode 100644
index 000000000..9f9d2e763
--- /dev/null
+++ b/man/man2/_Exit.2
@@ -0,0 +1 @@
+.so man2/_exit.2
diff --git a/man/man2/__clone2.2 b/man/man2/__clone2.2
new file mode 100644
index 000000000..68f41a5ba
--- /dev/null
+++ b/man/man2/__clone2.2
@@ -0,0 +1 @@
+.so man2/clone.2
diff --git a/man/man2/_exit.2 b/man/man2/_exit.2
new file mode 100644
index 000000000..08854a073
--- /dev/null
+++ b/man/man2/_exit.2
@@ -0,0 +1,138 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 21 23:02:38 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 2001-11-17, aeb
+.\"
+.TH _exit 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+_exit, _Exit \- terminate the calling process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "[[noreturn]] void _exit(int " status );
+.P
+.B #include <stdlib.h>
+.P
+.BI "[[noreturn]] void _Exit(int " status );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR _Exit ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.BR _exit ()
+terminates the calling process "immediately".
+Any open file descriptors belonging to the process are closed.
+Any children of the process are inherited by
+.BR init (1)
+(or by the nearest "subreaper" process as defined through the use of the
+.BR prctl (2)
+.B PR_SET_CHILD_SUBREAPER
+operation).
+The process's parent is sent a
+.B SIGCHLD
+signal.
+.P
+The value
+.I "status & 0xFF"
+is returned to the parent process as the process's exit status, and
+can be collected by the parent using one of the
+.BR wait (2)
+family of calls.
+.P
+The function
+.BR _Exit ()
+is equivalent to
+.BR _exit ().
+.SH RETURN VALUE
+These functions do not return.
+.SH STANDARDS
+.TP
+.BR _exit ()
+POSIX.1-2008.
+.TP
+.BR _Exit ()
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.P
+.BR _Exit ()
+was introduced by C99.
+.SH NOTES
+For a discussion on the effects of an exit, the transmission of
+exit status, zombie processes, signals sent, and so on, see
+.BR exit (3).
+.P
+The function
+.BR _exit ()
+is like
+.BR exit (3),
+but does not call any
+functions registered with
+.BR atexit (3)
+or
+.BR on_exit (3).
+Open
+.BR stdio (3)
+streams are not flushed.
+On the other hand,
+.BR _exit ()
+does close open file descriptors, and this may cause an unknown delay,
+waiting for pending output to finish.
+If the delay is undesired,
+it may be useful to call functions like
+.BR tcflush (3)
+before calling
+.BR _exit ().
+Whether any pending I/O is canceled, and which pending I/O may be
+canceled upon
+.BR _exit (),
+is implementation-dependent.
+.SS C library/kernel differences
+The text above in DESCRIPTION describes the traditional effect of
+.BR _exit (),
+which is to terminate a process,
+and these are the semantics specified by POSIX.1 and implemented
+by the C library wrapper function.
+On modern systems, this means termination of all threads in the process.
+.P
+By contrast with the C library wrapper function, the raw Linux
+.BR _exit ()
+system call terminates only the calling thread, and actions such as
+reparenting child processes or sending
+.B SIGCHLD
+to the parent process are performed only if this is
+the last thread in the thread group.
+.\" _exit() is used by pthread_exit() to terminate the calling thread
+.P
+Up to glibc 2.3, the
+.BR _exit ()
+wrapper function invoked the kernel system call of the same name.
+Since glibc 2.3, the wrapper function invokes
+.BR exit_group (2),
+in order to terminate all of the threads in a process.
+.SH SEE ALSO
+.BR execve (2),
+.BR exit_group (2),
+.BR fork (2),
+.BR kill (2),
+.BR wait (2),
+.BR wait4 (2),
+.BR waitpid (2),
+.BR atexit (3),
+.BR exit (3),
+.BR on_exit (3),
+.BR termios (3)
diff --git a/man/man2/_llseek.2 b/man/man2/_llseek.2
new file mode 100644
index 000000000..d15dbee55
--- /dev/null
+++ b/man/man2/_llseek.2
@@ -0,0 +1 @@
+.so man2/llseek.2
diff --git a/man/man2/_newselect.2 b/man/man2/_newselect.2
new file mode 100644
index 000000000..e17784318
--- /dev/null
+++ b/man/man2/_newselect.2
@@ -0,0 +1 @@
+.so man2/select.2
diff --git a/man/man2/_syscall.2 b/man/man2/_syscall.2
new file mode 100644
index 000000000..0b781a39e
--- /dev/null
+++ b/man/man2/_syscall.2
@@ -0,0 +1,171 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"   Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Tue Jul  6 12:42:46 MDT 1993 <dminer@nyx.cs.du.edu>
+.\" Added "Calling Directly" and supporting paragraphs
+.\"
+.\" Modified Sat Jul 24 15:19:12 1993 by Rik Faith <faith@cs.unc.edu>
+.\"
+.\" Modified 21 Aug 1994 by Michael Chastain <mec@shell.portal.com>:
+.\"   Added explanation of arg stacking when 6 or more args.
+.\"
+.\" Modified 10 June 1995 by Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" 2007-10-23 mtk: created as a new page, by taking the content
+.\" specific to the _syscall() macros from intro(2).
+.\"
+.TH _syscall 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+_syscall \- invoking a system call without library support (OBSOLETE)
+.SH SYNOPSIS
+.nf
+.B #include <linux/unistd.h>
+.P
+A _syscall macro
+.P
+desired system call
+.fi
+.SH DESCRIPTION
+The important thing to know about a system call is its prototype.
+You need to know how many arguments, their types,
+and the function return type.
+There are seven macros that make the actual call into the system easier.
+They have the form:
+.P
+.in +4n
+.EX
+.RI _syscall X ( type , name , type1 , arg1 , type2 , arg2 ,...)
+.EE
+.in
+.P
+where
+.IP
+.I X
+is 0\[en]6, which are the number of arguments taken by the
+system call
+.IP
+.I type
+is the return type of the system call
+.IP
+.I name
+is the name of the system call
+.IP
+.I typeN
+is the Nth argument's type
+.IP
+.I argN
+is the name of the Nth argument
+.P
+These macros create a function called
+.I name
+with the arguments you
+specify.
+Once you include the _syscall() in your source file,
+you call the system call by
+.IR name .
+.SH FILES
+.I /usr/include/linux/unistd.h
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Starting around Linux 2.6.18, the _syscall macros were removed
+from header files supplied to user space.
+Use
+.BR syscall (2)
+instead.
+(Some architectures, notably ia64, never provided the _syscall macros;
+on those architectures,
+.BR syscall (2)
+was always required.)
+.SH NOTES
+The _syscall() macros
+.I "do not"
+produce a prototype.
+You may have to
+create one, especially for C++ users.
+.P
+System calls are not required to return only positive or negative error
+codes.
+You need to read the source to be sure how it will return errors.
+Usually, it is the negative of a standard error code,
+for example,
+.RI \- EPERM .
+The _syscall() macros will return the result
+.I r
+of the system call
+when
+.I r
+is nonnegative, but will return \-1 and set the variable
+.I errno
+to
+.RI \- r
+when
+.I r
+is negative.
+For the error codes, see
+.BR errno (3).
+.P
+When defining a system call, the argument types
+.I must
+be
+passed by-value or by-pointer (for aggregates like structs).
+.\" The preferred way to invoke system calls that glibc does not know
+.\" about yet is via
+.\" .BR syscall (2).
+.\" However, this mechanism can be used only if using a libc
+.\" (such as glibc) that supports
+.\" .BR syscall (2),
+.\" and if the
+.\" .I <sys/syscall.h>
+.\" header file contains the required SYS_foo definition.
+.\" Otherwise, the use of a _syscall macro is required.
+.\"
+.SH EXAMPLES
+.\" SRC BEGIN (_syscall.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <linux/unistd.h>       /* for _syscallX macros/related stuff */
+#include <linux/kernel.h>       /* for struct sysinfo */
+\&
+_syscall1(int, sysinfo, struct sysinfo *, info);
+\&
+int
+main(void)
+{
+    struct sysinfo s_info;
+    int error;
+\&
+    error = sysinfo(&s_info);
+    printf("code error = %d\en", error);
+    printf("Uptime = %lds\enLoad: 1 min %lu / 5 min %lu / 15 min %lu\en"
+           "RAM: total %lu / free %lu / shared %lu\en"
+           "Memory in buffers = %lu\enSwap: total %lu / free %lu\en"
+           "Number of processes = %d\en",
+           s_info.uptime, s_info.loads[0],
+           s_info.loads[1], s_info.loads[2],
+           s_info.totalram, s_info.freeram,
+           s_info.sharedram, s_info.bufferram,
+           s_info.totalswap, s_info.freeswap,
+           s_info.procs);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SS Sample output
+.EX
+code error = 0
+uptime = 502034s
+Load: 1 min 13376 / 5 min 5504 / 15 min 1152
+RAM: total 15343616 / free 827392 / shared 8237056
+Memory in buffers = 5066752
+Swap: total 27881472 / free 24698880
+Number of processes = 40
+.EE
+.SH SEE ALSO
+.BR intro (2),
+.BR syscall (2),
+.BR errno (3)
diff --git a/man/man2/_sysctl.2 b/man/man2/_sysctl.2
new file mode 100644
index 000000000..9e14d4b16
--- /dev/null
+++ b/man/man2/_sysctl.2
@@ -0,0 +1 @@
+.so man2/sysctl.2
diff --git a/man/man2/accept.2 b/man/man2/accept.2
new file mode 100644
index 000000000..aed8660f3
--- /dev/null
+++ b/man/man2/accept.2
@@ -0,0 +1,349 @@
+.\" Copyright (c) 1983, 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-21 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998-2000 by Andi Kleen to match Linux 2.2 reality
+.\" Modified 2002-04-23 by Roger Luethi <rl@hellgate.ch>
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2008-12-04, mtk, Add documentation of accept4()
+.\"
+.TH accept 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+accept, accept4 \- accept a connection on a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int accept(int " sockfd ", struct sockaddr *_Nullable restrict " addr ,
+.BI "           socklen_t *_Nullable restrict " addrlen );
+.P
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sys/socket.h>
+.P
+.BI "int accept4(int " sockfd ", struct sockaddr *_Nullable restrict " addr ,
+.BI "           socklen_t *_Nullable restrict " addrlen ", int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR accept ()
+system call is used with connection-based socket types
+.RB ( SOCK_STREAM ,
+.BR SOCK_SEQPACKET ).
+It extracts the first connection request on the queue of pending
+connections for the listening socket,
+.IR sockfd ,
+creates a new connected socket, and returns a new file
+descriptor referring to that socket.
+The newly created socket is not in the listening state.
+The original socket
+.I sockfd
+is unaffected by this call.
+.P
+The argument
+.I sockfd
+is a socket that has been created with
+.BR socket (2),
+bound to a local address with
+.BR bind (2),
+and is listening for connections after a
+.BR listen (2).
+.P
+The argument
+.I addr
+is a pointer to a
+.I sockaddr
+structure.
+This structure is filled in with the address of the peer socket,
+as known to the communications layer.
+The exact format of the address returned
+.I addr
+is determined by the socket's address family (see
+.BR socket (2)
+and the respective protocol man pages).
+When
+.I addr
+is NULL, nothing is filled in; in this case,
+.I addrlen
+is not used, and should also be NULL.
+.P
+The
+.I addrlen
+argument is a value-result argument:
+the caller must initialize it to contain the
+size (in bytes) of the structure pointed to by
+.IR addr ;
+on return it will contain the actual size of the peer address.
+.P
+The returned address is truncated if the buffer provided is too small;
+in this case,
+.I addrlen
+will return a value greater than was supplied to the call.
+.P
+If no pending
+connections are present on the queue, and the socket is not marked as
+nonblocking,
+.BR accept ()
+blocks the caller until a connection is present.
+If the socket is marked
+nonblocking and no pending connections are present on the queue,
+.BR accept ()
+fails with the error
+.B EAGAIN
+or
+.BR EWOULDBLOCK .
+.P
+In order to be notified of incoming connections on a socket, you can use
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7).
+A readable event will be delivered when a new connection is attempted and you
+may then call
+.BR accept ()
+to get a socket for that connection.
+Alternatively, you can set the socket to deliver
+.B SIGIO
+when activity occurs on a socket; see
+.BR socket (7)
+for details.
+.P
+If
+.I flags
+is 0, then
+.BR accept4 ()
+is the same as
+.BR accept ().
+The following values can be bitwise ORed in
+.I flags
+to obtain different behavior:
+.TP 16
+.B SOCK_NONBLOCK
+Set the
+.B O_NONBLOCK
+file status flag on the open file description (see
+.BR open (2))
+referred to by the new file descriptor.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
+.TP
+.B SOCK_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.SH RETURN VALUE
+On success,
+these system calls return a file descriptor
+for the accepted socket (a nonnegative integer).
+On error, \-1 is returned,
+.I errno
+is set to indicate the error, and
+.I addrlen
+is left unchanged.
+.SS Error handling
+Linux
+.BR accept ()
+(and
+.BR accept4 ())
+passes already-pending network errors on the new socket
+as an error code from
+.BR accept ().
+This behavior differs from other BSD socket
+implementations.
+For reliable operation the application should detect
+the network errors defined for the protocol after
+.BR accept ()
+and treat
+them like
+.B EAGAIN
+by retrying.
+In the case of TCP/IP, these are
+.BR ENETDOWN ,
+.BR EPROTO ,
+.BR ENOPROTOOPT ,
+.BR EHOSTDOWN ,
+.BR ENONET ,
+.BR EHOSTUNREACH ,
+.BR EOPNOTSUPP ,
+and
+.BR ENETUNREACH .
+.SH ERRORS
+.TP
+.BR EAGAIN " or " EWOULDBLOCK
+.\" Actually EAGAIN on Linux
+The socket is marked nonblocking and no connections are
+present to be accepted.
+POSIX.1-2001 and POSIX.1-2008
+allow either error to be returned for this case,
+and do not require these constants to have the same value,
+so a portable application should check for both possibilities.
+.TP
+.B EBADF
+.I sockfd
+is not an open file descriptor.
+.TP
+.B ECONNABORTED
+A connection has been aborted.
+.TP
+.B EFAULT
+The
+.I addr
+argument is not in a writable part of the user address space.
+.TP
+.B EINTR
+The system call was interrupted by a signal that was caught
+before a valid connection arrived; see
+.BR signal (7).
+.TP
+.B EINVAL
+Socket is not listening for connections, or
+.I addrlen
+is invalid (e.g., is negative).
+.TP
+.B EINVAL
+.RB ( accept4 ())
+invalid value in
+.IR flags .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOBUFS
+.TQ
+.B ENOMEM
+Not enough free memory.
+This often means that the memory allocation is limited by the socket buffer
+limits, not by the system memory.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.TP
+.B EOPNOTSUPP
+The referenced socket is not of type
+.BR SOCK_STREAM .
+.TP
+.B EPERM
+Firewall rules forbid connection.
+.TP
+.B EPROTO
+Protocol error.
+.P
+In addition, network errors for the new socket and as defined
+for the protocol may be returned.
+Various Linux kernels can
+return other errors such as
+.BR ENOSR ,
+.BR ESOCKTNOSUPPORT ,
+.BR EPROTONOSUPPORT ,
+.BR ETIMEDOUT .
+The value
+.B ERESTARTSYS
+may be seen during a trace.
+.SH VERSIONS
+On Linux, the new socket returned by
+.BR accept ()
+does \fInot\fP inherit file status flags such as
+.B O_NONBLOCK
+and
+.B O_ASYNC
+from the listening socket.
+This behavior differs from the canonical BSD sockets implementation.
+.\" Some testing seems to show that Tru64 5.1 and HP-UX 11 also
+.\" do not inherit file status flags -- MTK Jun 05
+Portable programs should not rely on inheritance or noninheritance
+of file status flags and always explicitly set all required flags on
+the socket returned from
+.BR accept ().
+.SH STANDARDS
+.TP
+.BR accept ()
+POSIX.1-2008.
+.TP
+.BR accept4 ()
+Linux.
+.SH HISTORY
+.TP
+.BR accept ()
+POSIX.1-2001, SVr4, 4.4BSD
+.RB ( accept ()
+first appeared in 4.2BSD).
+.\" The BSD man page documents five possible error returns
+.\" (EBADF, ENOTSOCK, EOPNOTSUPP, EWOULDBLOCK, EFAULT).
+.\" POSIX.1-2001 documents errors
+.\" EAGAIN, EBADF, ECONNABORTED, EINTR, EINVAL, EMFILE,
+.\" ENFILE, ENOBUFS, ENOMEM, ENOTSOCK, EOPNOTSUPP, EPROTO, EWOULDBLOCK.
+.\" In addition, SUSv2 documents EFAULT and ENOSR.
+.TP
+.BR accept4 ()
+Linux 2.6.28,
+glibc 2.10.
+.SH NOTES
+There may not always be a connection waiting after a
+.B SIGIO
+is delivered or
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7)
+return a readability event because the connection might have been
+removed by an asynchronous network error or another thread before
+.BR accept ()
+is called.
+If this happens, then the call will block waiting for the next
+connection to arrive.
+To ensure that
+.BR accept ()
+never blocks, the passed socket
+.I sockfd
+needs to have the
+.B O_NONBLOCK
+flag set (see
+.BR socket (7)).
+.P
+For certain protocols which require an explicit confirmation,
+such as DECnet,
+.BR accept ()
+can be thought of as merely dequeuing the next connection request and not
+implying confirmation.
+Confirmation can be implied by
+a normal read or write on the new file descriptor, and rejection can be
+implied by closing the new socket.
+Currently, only DECnet has these semantics on Linux.
+.\"
+.SS The socklen_t type
+In the original BSD sockets implementation (and on other older systems)
+.\" such as Linux libc4 and libc5, SunOS 4, SGI
+the third argument of
+.BR accept ()
+was declared as an \fIint\ *\fP.
+A POSIX.1g draft
+standard wanted to change it into a \fIsize_t\ *\fPC;
+.\" SunOS 5 has 'size_t *'
+later POSIX standards and glibc 2.x have
+.IR "socklen_t\ * ".
+.SH EXAMPLES
+See
+.BR bind (2).
+.SH SEE ALSO
+.BR bind (2),
+.BR connect (2),
+.BR listen (2),
+.BR select (2),
+.BR socket (2),
+.BR socket (7)
diff --git a/man/man2/accept4.2 b/man/man2/accept4.2
new file mode 100644
index 000000000..963dfb54c
--- /dev/null
+++ b/man/man2/accept4.2
@@ -0,0 +1 @@
+.so man2/accept.2
diff --git a/man/man2/access.2 b/man/man2/access.2
new file mode 100644
index 000000000..2b3e70e34
--- /dev/null
+++ b/man/man2/access.2
@@ -0,0 +1,468 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\" and Copyright (C) 2004, 2006, 2007, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-21 Rik Faith (faith@cs.unc.edu)
+.\" Modified 1994-08-21 by Michael Chastain (mec@shell.portal.com):
+.\"   Removed note about old kernel (pre-1.1.44) using wrong id on path.
+.\" Modified 1996-03-18 by Martin Schulze (joey@infodrom.north.de):
+.\"   Stated more clearly how it behaves with symbolic links.
+.\" Added correction due to Nick Duffek (nsd@bbc.com), aeb, 960426
+.\" Modified 1996-09-07 by Michael Haardt:
+.\"   Restrictions for NFS
+.\" Modified 1997-09-09 by Joseph S. Myers <jsm28@cam.ac.uk>
+.\" Modified 1998-01-13 by Michael Haardt:
+.\"   Using access is often insecure
+.\" Modified 2001-10-16 by aeb
+.\" Modified 2002-04-23 by Roger Luethi <rl@hellgate.ch>
+.\" Modified 2004-06-23 by Michael Kerrisk
+.\" 2007-06-10, mtk, various parts rewritten, and added BUGS section.
+.\"
+.TH access 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+access, faccessat, faccessat2 \- check user's permissions for a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int access(const char *" pathname ", int " mode );
+.P
+.BR "#include <fcntl.h>" "            /* Definition of " AT_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int faccessat(int " dirfd ", const char *" pathname ", int " \
+mode ", int " flags );
+                /* But see C library/kernel differences, below */
+.P
+.BR "#include <fcntl.h>" "            /* Definition of " AT_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.B int syscall(SYS_faccessat2,
+.BI "            int " dirfd ", const char *" pathname ", int " mode \
+", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR faccessat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+.BR access ()
+checks whether the calling process can access the file
+.IR pathname .
+If
+.I pathname
+is a symbolic link, it is dereferenced.
+.P
+The
+.I mode
+specifies the accessibility check(s) to be performed,
+and is either the value
+.BR F_OK ,
+.\" F_OK is defined as 0 on every system that I know of.
+or a mask consisting of the bitwise OR of one or more of
+.BR R_OK ", " W_OK ", and " X_OK .
+.B F_OK
+tests for the existence of the file.
+.BR R_OK ", " W_OK ", and " X_OK
+test whether the file exists and grants read, write, and
+execute permissions, respectively.
+.P
+The check is done using the calling process's
+.I real
+UID and GID, rather than the effective IDs as is done when
+actually attempting an operation (e.g.,
+.BR open (2))
+on the file.
+Similarly, for the root user, the check uses the set of
+permitted capabilities rather than the set of effective
+capabilities; and for non-root users, the check uses an empty set
+of capabilities.
+.P
+This allows set-user-ID programs and capability-endowed programs
+to easily determine the invoking user's authority.
+In other words,
+.BR access ()
+does not answer the "can I read/write/execute this file?" question.
+It answers a slightly different question:
+"(assuming I'm a setuid binary) can
+.I the user who invoked me
+read/write/execute this file?",
+which gives set-user-ID programs the possibility to
+prevent malicious users from causing them to read files
+which users shouldn't be able to read.
+.P
+If the calling process is privileged (i.e., its real UID is zero),
+then an
+.B X_OK
+check is successful for a regular file if execute permission
+is enabled for any of the file owner, group, or other.
+.SS faccessat()
+.BR faccessat ()
+operates in exactly the same way as
+.BR access (),
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR access ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR access ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+.I flags
+is constructed by ORing together zero or more of the following values:
+.TP
+.B AT_EACCESS
+Perform access checks using the effective user and group IDs.
+By default,
+.BR faccessat ()
+uses the real IDs (like
+.BR access ()).
+.TP
+.BR AT_EMPTY_PATH " (since Linux 5.8)"
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.I dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+In this case,
+.I dirfd
+can refer to any type of file, not just a directory.
+If
+.I dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+to obtain its definition.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+is a symbolic link, do not dereference it:
+instead return information about the link itself.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR faccessat ().
+.\"
+.SS faccessat2()
+The description of
+.BR faccessat ()
+given above corresponds to POSIX.1 and
+to the implementation provided by glibc.
+However, the glibc implementation was an imperfect emulation (see BUGS)
+that papered over the fact that the raw Linux
+.BR faccessat ()
+system call does not have a
+.I flags
+argument.
+To allow for a proper implementation, Linux 5.8 added the
+.BR faccessat2 ()
+system call, which supports the
+.I flags
+argument and allows a correct implementation of the
+.BR faccessat ()
+wrapper function.
+.SH RETURN VALUE
+On success (all requested permissions granted, or
+.I mode
+is
+.B F_OK
+and the file exists), zero is returned.
+On error (at least one bit in
+.I mode
+asked for a permission that is denied, or
+.I mode
+is
+.B F_OK
+and the file does not exist, or some other error occurred),
+\-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The requested access would be denied to the file, or search permission
+is denied for one of the directories in the path prefix of
+.IR pathname .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( faccessat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+.RB ( faccessat ())
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I pathname
+points outside your accessible address space.
+.TP
+.B EINVAL
+.I mode
+was incorrectly specified.
+.TP
+.B EINVAL
+.RB ( faccessat ())
+Invalid flag specified in
+.IR flags .
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+A component of
+.I pathname
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.I pathname
+is not, in fact, a directory.
+.TP
+.B ENOTDIR
+.RB ( faccessat ())
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EPERM
+Write permission was requested to a file that has the immutable flag set.
+See also
+.BR ioctl_iflags (2).
+.TP
+.B EROFS
+Write permission was requested for a file on a read-only filesystem.
+.TP
+.B ETXTBSY
+Write access was requested to an executable which is being
+executed.
+.SH VERSIONS
+If the calling process has appropriate privileges (i.e., is superuser),
+POSIX.1-2001 permits an implementation to indicate success for an
+.B X_OK
+check even if none of the execute file permission bits are set.
+.\" HPU-UX 11 and Tru64 5.1 do this.
+Linux does not do this.
+.\"
+.SS C library/kernel differences
+The raw
+.BR faccessat ()
+system call takes only the first three arguments.
+The
+.B AT_EACCESS
+and
+.B AT_SYMLINK_NOFOLLOW
+flags are actually implemented within the glibc wrapper function for
+.BR faccessat ().
+If either of these flags is specified, then the wrapper function employs
+.BR fstatat (2)
+to determine access permissions, but see BUGS.
+.\"
+.SS glibc notes
+On older kernels where
+.BR faccessat ()
+is unavailable (and when the
+.B AT_EACCESS
+and
+.B AT_SYMLINK_NOFOLLOW
+flags are not specified),
+the glibc wrapper function falls back to the use of
+.BR access ().
+When
+.I pathname
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.I /proc/self/fd
+that corresponds to the
+.I dirfd
+argument.
+.SH STANDARDS
+.TP
+.BR access ()
+.TQ
+.BR faccessat ()
+POSIX.1-2008.
+.TP
+.BR faccessat2 ()
+Linux.
+.SH HISTORY
+.TP
+.BR access ()
+SVr4, 4.3BSD, POSIX.1-2001.
+.TP
+.BR faccessat ()
+Linux 2.6.16,
+glibc 2.4.
+.TP
+.BR faccessat2 ()
+Linux 5.8.
+.SH NOTES
+.BR Warning :
+Using these calls to check if a user is authorized to, for example,
+open a file before actually doing so using
+.BR open (2)
+creates a security hole, because the user might exploit the short time
+interval between checking and opening the file to manipulate it.
+.BR "For this reason, the use of this system call should be avoided" .
+(In the example just described,
+a safer alternative would be to temporarily switch the process's
+effective user ID to the real ID and then call
+.BR open (2).)
+.P
+.BR access ()
+always dereferences symbolic links.
+If you need to check the permissions on a symbolic link, use
+.BR faccessat ()
+with the flag
+.BR AT_SYMLINK_NOFOLLOW .
+.P
+These calls return an error if any of the access types in
+.I mode
+is denied, even if some of the other access types in
+.I mode
+are permitted.
+.P
+A file is accessible only if the permissions on each of the
+directories in the path prefix of
+.I pathname
+grant search (i.e., execute) access.
+If any directory is inaccessible, then the
+.BR access ()
+call fails, regardless of the permissions on the file itself.
+.P
+Only access bits are checked, not the file type or contents.
+Therefore, if a directory is found to be writable,
+it probably means that files can be created in the directory,
+and not that the directory can be written as a file.
+Similarly, a DOS file may be reported as executable, but the
+.BR execve (2)
+call will still fail.
+.P
+These calls
+may not work correctly on NFSv2 filesystems with UID mapping enabled,
+because UID mapping is done on the server and hidden from the client,
+which checks permissions.
+(NFS versions 3 and higher perform the check on the server.)
+Similar problems can occur to FUSE mounts.
+.\"
+.SH BUGS
+Because the Linux kernel's
+.BR faccessat ()
+system call does not support a
+.I flags
+argument, the glibc
+.BR faccessat ()
+wrapper function provided in glibc 2.32 and earlier
+emulates the required functionality using
+a combination of the
+.BR faccessat ()
+system call and
+.BR fstatat (2).
+However, this emulation does not take ACLs into account.
+Starting with glibc 2.33, the wrapper function avoids this bug
+by making use of the
+.BR faccessat2 ()
+system call where it is provided by the underlying kernel.
+.P
+In Linux 2.4 (and earlier) there is some strangeness in the handling of
+.B X_OK
+tests for superuser.
+If all categories of execute permission are disabled
+for a nondirectory file, then the only
+.BR access ()
+test that returns \-1 is when
+.I mode
+is specified as just
+.BR X_OK ;
+if
+.B R_OK
+or
+.B W_OK
+is also specified in
+.IR mode ,
+then
+.BR access ()
+returns 0 for such files.
+.\" This behavior appears to have been an implementation accident.
+Early Linux 2.6 (up to and including Linux 2.6.3)
+also behaved in the same way as Linux 2.4.
+.P
+Before Linux 2.6.20,
+these calls ignored the effect of the
+.B MS_NOEXEC
+flag if it was used to
+.BR mount (2)
+the underlying filesystem.
+Since Linux 2.6.20, the
+.B MS_NOEXEC
+flag is honored.
+.SH SEE ALSO
+.BR chmod (2),
+.BR chown (2),
+.BR open (2),
+.BR setgid (2),
+.BR setuid (2),
+.BR stat (2),
+.BR euidaccess (3),
+.BR credentials (7),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/acct.2 b/man/man2/acct.2
new file mode 100644
index 000000000..8c7414bb7
--- /dev/null
+++ b/man/man2/acct.2
@@ -0,0 +1,136 @@
+.\" Copyright (c) 1993 Michael Haardt
+.\" (michael@moria.de),
+.\" Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 1993-07-22 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1993-08-10 by Alan Cox <iiitac@pyramid.swansea.ac.uk>
+.\" Modified 1998-11-04 by Tigran Aivazian <tigran@sco.com>
+.\" Modified 2004-05-27, 2004-06-17, 2004-06-23 by Michael Kerrisk
+.\"
+.TH acct 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+acct \- switch process accounting on or off
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int acct(const char *_Nullable " filename );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR acct ():
+.nf
+    Since glibc 2.21:
+.\"		commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+The
+.BR acct ()
+system call enables or disables process accounting.
+If called with the name of an existing file as its argument,
+accounting is turned on,
+and records for each terminating process are appended to
+.I filename
+as it terminates.
+An argument of NULL causes accounting to be turned off.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Write permission is denied for the specified file,
+or search permission is denied for one of the directories
+in the path prefix of
+.I filename
+(see also
+.BR path_resolution (7)),
+or
+.I filename
+is not a regular file.
+.TP
+.B EFAULT
+.I filename
+points outside your accessible address space.
+.TP
+.B EIO
+Error writing to the file
+.IR filename .
+.TP
+.B EISDIR
+.I filename
+is a directory.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR filename .
+.TP
+.B ENAMETOOLONG
+.I filename
+was too long.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+The specified file does not exist.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ENOSYS
+BSD process accounting has not been enabled when the operating system
+kernel was compiled.
+The kernel configuration parameter controlling this feature is
+.BR CONFIG_BSD_PROCESS_ACCT .
+.TP
+.B ENOTDIR
+A component used as a directory in
+.I filename
+is not in fact a directory.
+.TP
+.B EPERM
+The calling process has insufficient privilege to enable process accounting.
+On Linux, the
+.B CAP_SYS_PACCT
+capability is required.
+.TP
+.B EROFS
+.I filename
+refers to a file on a read-only filesystem.
+.TP
+.B EUSERS
+There are no more free file structures or we ran out of memory.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4, 4.3BSD.
+.\" SVr4 documents an EBUSY error condition, but no EISDIR or ENOSYS.
+.\" Also AIX and HP-UX document EBUSY (attempt is made
+.\" to enable accounting when it is already enabled), as does Solaris
+.\" (attempt is made to enable accounting using the same file that is
+.\" currently being used).
+.SH NOTES
+No accounting is produced for programs running when a system crash occurs.
+In particular, nonterminating processes are never accounted for.
+.P
+The structure of the records written to the accounting file is described in
+.BR acct (5).
+.SH SEE ALSO
+.BR acct (5)
diff --git a/man/man2/add_key.2 b/man/man2/add_key.2
new file mode 100644
index 000000000..2b017f680
--- /dev/null
+++ b/man/man2/add_key.2
@@ -0,0 +1,298 @@
+.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+.\"     Written by David Howells (dhowells@redhat.com)
+.\" and Copyright (C) 2016 Michael Kerrisk <mtk.man-pages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH add_key 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+add_key \- add a key to the kernel's key management facility
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <keyutils.h>
+.P
+.BI "key_serial_t add_key(const char *" type ", const char *" description ,
+.BI "                     const void " payload [. plen "], size_t " plen ,
+.BI "                     key_serial_t " keyring ");"
+.fi
+.P
+.IR Note :
+There is no glibc wrapper for this system call; see NOTES.
+.SH DESCRIPTION
+.BR add_key ()
+creates or updates a key of the given
+.I type
+and
+.IR description ,
+instantiates it with the
+.I payload
+of length
+.IR plen ,
+attaches it to the nominated
+.IR keyring ,
+and returns the key's serial number.
+.P
+The key may be rejected if the provided data is in the wrong format or
+it is invalid in some other way.
+.P
+If the destination
+.I keyring
+already contains a key that matches the specified
+.I type
+and
+.IR description ,
+then, if the key type supports it,
+.\" FIXME The aforementioned phrases begs the question:
+.\" which key types support this?
+that key will be updated rather than a new key being created;
+if not, a new key (with a different ID) will be created
+and it will displace the link to the extant key from the keyring.
+.\" FIXME Perhaps elaborate the implications here? Namely, the new
+.\" key will have a new ID, and if the old key was a keyring that
+.\" is consequently unlinked, then keys that it was anchoring
+.\" will have their reference count decreased by one (and may
+.\" consequently be garbage collected). Is this all correct?
+.P
+The destination
+.I keyring
+serial number may be that of a valid keyring for which the caller has
+.I write
+permission.
+Alternatively, it may be one of the following special keyring IDs:
+.\" FIXME . Perhaps have a separate page describing special keyring IDs?
+.TP
+.B KEY_SPEC_THREAD_KEYRING
+This specifies the caller's thread-specific keyring
+.RB ( thread\-keyring (7)).
+.TP
+.B KEY_SPEC_PROCESS_KEYRING
+This specifies the caller's process-specific keyring
+.RB ( process\-keyring (7)).
+.TP
+.B KEY_SPEC_SESSION_KEYRING
+This specifies the caller's session-specific keyring
+.RB ( session\-keyring (7)).
+.TP
+.B KEY_SPEC_USER_KEYRING
+This specifies the caller's UID-specific keyring
+.RB ( user\-keyring (7)).
+.TP
+.B KEY_SPEC_USER_SESSION_KEYRING
+This specifies the caller's UID-session keyring
+.RB ( user\-session\-keyring (7)).
+.SS Key types
+The key
+.I type
+is a string that specifies the key's type.
+Internally, the kernel defines a number of key types that are
+available in the core key management code.
+Among the types that are available for user-space use
+and can be specified as the
+.I type
+argument to
+.BR add_key ()
+are the following:
+.TP
+.I \[dq]keyring\[dq]
+Keyrings are special key types that may contain links to sequences of other
+keys of any type.
+If this interface is used to create a keyring, then
+.I payload
+should be NULL and
+.I plen
+should be zero.
+.TP
+.I \[dq]user\[dq]
+This is a general purpose key type whose payload may be read and updated
+by user-space applications.
+The key is kept entirely within kernel memory.
+The payload for keys of this type is a blob of arbitrary data
+of up to 32,767 bytes.
+.TP
+.IR \[dq]logon\[dq] " (since Linux 3.3)"
+.\" commit 9f6ed2ca257fa8650b876377833e6f14e272848b
+This key type is essentially the same as
+.IR \[dq]user\[dq] ,
+but it does not permit the key to read.
+This is suitable for storing payloads
+that you do not want to be readable from user space.
+.P
+This key type vets the
+.I description
+to ensure that it is qualified by a "service" prefix,
+by checking to ensure that the
+.I description
+contains a ':' that is preceded by other characters.
+.TP
+.IR \[dq]big_key\[dq] " (since Linux 3.13)"
+.\" commit ab3c3587f8cda9083209a61dbe3a4407d3cada10
+This key type is similar to
+.IR \[dq]user\[dq] ,
+but may hold a payload of up to 1\ MiB.
+If the key payload is large enough,
+then it may be stored encrypted in tmpfs
+(which can be swapped out) rather than kernel memory.
+.P
+For further details on these key types, see
+.BR keyrings (7).
+.SH RETURN VALUE
+On success,
+.BR add_key ()
+returns the serial number of the key it created or updated.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The keyring wasn't available for modification by the user.
+.TP
+.B EDQUOT
+The key quota for this user would be exceeded by creating this key or linking
+it to the keyring.
+.TP
+.B EFAULT
+One or more of
+.IR type ,
+.IR description ,
+and
+.I payload
+points outside process's accessible address space.
+.TP
+.B EINVAL
+The size of the string (including the terminating null byte) specified in
+.I type
+or
+.I description
+exceeded the limit (32 bytes and 4096 bytes respectively).
+.TP
+.B EINVAL
+The payload data was invalid.
+.TP
+.B EINVAL
+.I type
+was
+.I \[dq]logon\[dq]
+and the
+.I description
+was not qualified with a prefix string of the form
+.IR \[dq]service:\[dq] .
+.TP
+.B EKEYEXPIRED
+The keyring has expired.
+.TP
+.B EKEYREVOKED
+The keyring has been revoked.
+.TP
+.B ENOKEY
+The keyring doesn't exist.
+.TP
+.B ENOMEM
+Insufficient memory to create a key.
+.TP
+.B EPERM
+The
+.I type
+started with a period (\[aq].\[aq]).
+Key types that begin with a period are reserved to the implementation.
+.TP
+.B EPERM
+.I type
+was
+.I \[dq]keyring\[dq]
+and the
+.I description
+started with a period (\[aq].\[aq]).
+Keyrings with descriptions (names)
+that begin with a period are reserved to the implementation.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.10.
+.SH NOTES
+glibc does not provide a wrapper for this system call.
+A wrapper is provided in the
+.I libkeyutils
+library.
+(The accompanying package provides the
+.I <keyutils.h>
+header file.)
+When employing the wrapper in that library, link with
+.IR \-lkeyutils .
+.SH EXAMPLES
+The program below creates a key with the type, description, and payload
+specified in its command-line arguments,
+and links that key into the session keyring.
+The following shell session demonstrates the use of the program:
+.P
+.in +4n
+.EX
+$ \fB./a.out user mykey "Some payload"\fP
+Key ID is 64a4dca
+$ \fBgrep \[aq]64a4dca\[aq] /proc/keys\fP
+064a4dca I\-\-Q\-\-\-    1 perm 3f010000  1000  1000 user    mykey: 12
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (add_key.c)
+.EX
+#include <keyutils.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    key_serial_t key;
+\&
+    if (argc != 4) {
+        fprintf(stderr, "Usage: %s type description payload\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    key = add_key(argv[1], argv[2], argv[3], strlen(argv[3]),
+                  KEY_SPEC_SESSION_KEYRING);
+    if (key == \-1) {
+        perror("add_key");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Key ID is %jx\en", (uintmax_t) key);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR keyctl (2),
+.BR request_key (2),
+.BR keyctl (3),
+.BR keyrings (7),
+.BR keyutils (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7),
+.BR user\-session\-keyring (7)
+.P
+The kernel source files
+.I Documentation/security/keys/core.rst
+and
+.I Documentation/keys/request\-key.rst
+(or, before Linux 4.13, in the files
+.\" commit b68101a1e8f0263dbc7b8375d2a7c57c6216fb76
+.I Documentation/security/keys.txt
+and
+.\" commit 3db38ed76890565772fcca3279cc8d454ea6176b
+.IR Documentation/security/keys\-request\-key.txt ).
diff --git a/man/man2/adjtimex.2 b/man/man2/adjtimex.2
new file mode 100644
index 000000000..c7c095f5e
--- /dev/null
+++ b/man/man2/adjtimex.2
@@ -0,0 +1,595 @@
+'\" t
+.\" Copyright (c) 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995.
+.\" and Copyright (C) 2014, 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1997-07-30 by Paul Slootman <paul@wurtel.demon.nl>
+.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH adjtimex 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+adjtimex, clock_adjtime, ntp_adjtime \- tune kernel clock
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/timex.h>
+.P
+.BI "int adjtimex(struct timex *" "buf" );
+.P
+.BI "int clock_adjtime(clockid_t " clk_id, " struct timex *" "buf" );
+.P
+.BI "int ntp_adjtime(struct timex *" buf );
+.fi
+.SH DESCRIPTION
+Linux uses David L.\& Mills' clock adjustment algorithm (see RFC\ 5905).
+The system call
+.BR adjtimex ()
+reads and optionally sets adjustment parameters for this algorithm.
+It takes a pointer to a
+.I timex
+structure, updates kernel parameters from (selected) field values,
+and returns the same structure updated with the current kernel values.
+This structure is declared as follows:
+.P
+.in +4n
+.EX
+struct timex {
+    int  modes;      /* Mode selector */
+    long offset;     /* Time offset; nanoseconds, if STA_NANO
+                        status flag is set, otherwise
+                        microseconds */
+    long freq;       /* Frequency offset; see NOTES for units */
+    long maxerror;   /* Maximum error (microseconds) */
+    long esterror;   /* Estimated error (microseconds) */
+    int  status;     /* Clock command/status */
+    long constant;   /* PLL (phase\-locked loop) time constant */
+    long precision;  /* Clock precision
+                        (microseconds, read\-only) */
+    long tolerance;  /* Clock frequency tolerance (read\-only);
+                        see NOTES for units */
+    struct timeval time;
+                     /* Current time (read\-only, except for
+                        ADJ_SETOFFSET); upon return, time.tv_usec
+                        contains nanoseconds, if STA_NANO status
+                        flag is set, otherwise microseconds */
+    long tick;       /* Microseconds between clock ticks */
+    long ppsfreq;    /* PPS (pulse per second) frequency
+                        (read\-only); see NOTES for units */
+    long jitter;     /* PPS jitter (read\-only); nanoseconds, if
+                        STA_NANO status flag is set, otherwise
+                        microseconds */
+    int  shift;      /* PPS interval duration
+                        (seconds, read\-only) */
+    long stabil;     /* PPS stability (read\-only);
+                        see NOTES for units */
+    long jitcnt;     /* PPS count of jitter limit exceeded
+                        events (read\-only) */
+    long calcnt;     /* PPS count of calibration intervals
+                        (read\-only) */
+    long errcnt;     /* PPS count of calibration errors
+                        (read\-only) */
+    long stbcnt;     /* PPS count of stability limit exceeded
+                        events (read\-only) */
+    int tai;         /* TAI offset, as set by previous ADJ_TAI
+                        operation (seconds, read\-only,
+                        since Linux 2.6.26) */
+    /* Further padding bytes to allow for future expansion */
+};
+.EE
+.in
+.P
+The
+.I modes
+field determines which parameters, if any, to set.
+(As described later in this page,
+the constants used for
+.BR ntp_adjtime ()
+are equivalent but differently named.)
+It is a bit mask containing a
+bitwise OR
+combination of zero or more of the following bits:
+.TP
+.B ADJ_OFFSET
+Set time offset from
+.IR buf.offset .
+Since Linux 2.6.26,
+.\" commit 074b3b87941c99bc0ce35385b5817924b1ed0c23
+the supplied value is clamped to the range (\-0.5s, +0.5s).
+In older kernels, an
+.B EINVAL
+error occurs if the supplied value is out of range.
+.TP
+.B ADJ_FREQUENCY
+Set frequency offset from
+.IR buf.freq .
+Since Linux 2.6.26,
+.\" commit 074b3b87941c99bc0ce35385b5817924b1ed0c23
+the supplied value is clamped to the range (\-32768000, +32768000).
+In older kernels, an
+.B EINVAL
+error occurs if the supplied value is out of range.
+.TP
+.B ADJ_MAXERROR
+Set maximum time error from
+.IR buf.maxerror .
+.TP
+.B ADJ_ESTERROR
+Set estimated time error from
+.IR buf.esterror .
+.TP
+.B ADJ_STATUS
+Set clock status bits from
+.IR buf.status .
+A description of these bits is provided below.
+.TP
+.B ADJ_TIMECONST
+Set PLL time constant from
+.IR buf.constant .
+If the
+.B STA_NANO
+status flag (see below) is clear, the kernel adds 4 to this value.
+.TP
+.BR ADJ_SETOFFSET " (since Linux 2.6.39)"
+.\" commit 094aa1881fdc1b8889b442eb3511b31f3ec2b762
+.\" Author: Richard Cochran <richardcochran@gmail.com>
+Add
+.I buf.time
+to the current time.
+If
+.I buf.status
+includes the
+.B ADJ_NANO
+flag, then
+.I buf.time.tv_usec
+is interpreted as a nanosecond value;
+otherwise it is interpreted as microseconds.
+.IP
+The value of
+.I buf.time
+is the sum of its two fields, but the
+field
+.I buf.time.tv_usec
+must always be nonnegative.
+The following example shows how to
+normalize a
+.I timeval
+with nanosecond resolution.
+.IP
+.in +4n
+.EX
+while (buf.time.tv_usec < 0) {
+    buf.time.tv_sec  \-= 1;
+    buf.time.tv_usec += 1000000000;
+}
+.EE
+.in
+.TP
+.BR ADJ_MICRO " (since Linux 2.6.26)"
+.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
+.\" Author: Roman Zippel <zippel@linux-m68k.org>
+Select microsecond resolution.
+.TP
+.BR ADJ_NANO " (since Linux 2.6.26)"
+.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
+.\" Author: Roman Zippel <zippel@linux-m68k.org>
+Select nanosecond resolution.
+Only one of
+.B ADJ_MICRO
+and
+.B ADJ_NANO
+should be specified.
+.TP
+.BR ADJ_TAI " (since Linux 2.6.26)"
+.\" commit 153b5d054ac2d98ea0d86504884326b6777f683d
+Set TAI (Atomic International Time) offset from
+.IR buf.constant .
+.IP
+.B ADJ_TAI
+should not be used in conjunction with
+.BR ADJ_TIMECONST ,
+since the latter mode also employs the
+.I buf.constant
+field.
+.IP
+For a complete explanation of TAI
+and the difference between TAI and UTC, see
+.UR http://www.bipm.org/en/bipm/tai/tai.html
+.I BIPM
+.UE
+.TP
+.B ADJ_TICK
+Set tick value from
+.IR buf.tick .
+.P
+Alternatively,
+.I modes
+can be specified as either of the following (multibit mask) values,
+in which case other bits should not be specified in
+.IR modes :
+.\" In general, the other bits are ignored, but ADJ_OFFSET_SINGLESHOT 0x8001
+.\" ORed with ADJ_NANO (0x2000) gives 0xa0001 == ADJ_OFFSET_SS_READ!!
+.TP
+.B ADJ_OFFSET_SINGLESHOT
+.\" In user space, ADJ_OFFSET_SINGLESHOT is 0x8001
+.\" In kernel space it is 0x0001, and must be ANDed with ADJ_ADJTIME (0x8000)
+Old-fashioned
+.BR adjtime (3):
+(gradually) adjust time by value specified in
+.IR buf.offset ,
+which specifies an adjustment in microseconds.
+.TP
+.BR ADJ_OFFSET_SS_READ " (functional since Linux 2.6.28)"
+.\" In user space, ADJ_OFFSET_SS_READ is 0xa001
+.\" In kernel space there is ADJ_OFFSET_READONLY (0x2000) anded with
+.\" ADJ_ADJTIME (0x8000) and ADJ_OFFSET_SINGLESHOT (0x0001) to give 0xa001)
+Return (in
+.IR buf.offset )
+the remaining amount of time to be adjusted after an earlier
+.B ADJ_OFFSET_SINGLESHOT
+operation.
+This feature was added in Linux 2.6.24,
+.\" commit 52bfb36050c8529d9031d2c2513b281a360922ec
+but did not work correctly
+.\" commit 916c7a855174e3b53d182b97a26b2e27a29726a1
+until Linux 2.6.28.
+.P
+Ordinary users are restricted to a value of either 0 or
+.B ADJ_OFFSET_SS_READ
+for
+.IR modes .
+Only the superuser may set any parameters.
+.P
+The
+.I buf.status
+field is a bit mask that is used to set and/or retrieve status
+bits associated with the NTP implementation.
+Some bits in the mask are both readable and settable,
+while others are read-only.
+.TP
+.BR STA_PLL " (read-write)"
+Enable phase-locked loop (PLL) updates via
+.BR ADJ_OFFSET .
+.TP
+.BR STA_PPSFREQ " (read-write)"
+Enable PPS (pulse-per-second) frequency discipline.
+.TP
+.BR STA_PPSTIME " (read-write)"
+Enable PPS time discipline.
+.TP
+.BR STA_FLL " (read-write)"
+Select frequency-locked loop (FLL) mode.
+.TP
+.BR STA_INS " (read-write)"
+Insert a leap second after the last second of the UTC day,
+thus extending the last minute of the day by one second.
+Leap-second insertion will occur each day, so long as this flag remains set.
+.\" John Stultz;
+.\"     Usually this is written as extending the day by one second,
+.\"     which is represented as:
+.\"        23:59:59
+.\"        23:59:60
+.\"        00:00:00
+.\"
+.\"     But since posix cannot represent 23:59:60, we repeat the last second:
+.\"        23:59:59 + TIME_INS
+.\"        23:59:59 + TIME_OOP
+.\"        00:00:00 + TIME_WAIT
+.\"
+.TP
+.BR STA_DEL " (read-write)"
+Delete a leap second at the last second of the UTC day.
+.\" John Stultz:
+.\"     Similarly the progression here is:
+.\"        23:59:57 + TIME_DEL
+.\"        23:59:58 + TIME_DEL
+.\"        00:00:00 + TIME_WAIT
+Leap second deletion will occur each day, so long as this flag
+remains set.
+.\" FIXME Does there need to be a statement that it is nonsensical to set
+.\" to set both STA_INS and STA_DEL?
+.TP
+.BR STA_UNSYNC " (read-write)"
+Clock unsynchronized.
+.TP
+.BR STA_FREQHOLD " (read-write)"
+Hold frequency.
+.\" Following text from John Stultz:
+Normally adjustments made via
+.B ADJ_OFFSET
+result in dampened frequency adjustments also being made.
+So a single call corrects the current offset,
+but as offsets in the same direction are made repeatedly,
+the small frequency adjustments will accumulate to fix the long-term skew.
+.IP
+This flag prevents the small frequency adjustment from being made
+when correcting for an
+.B ADJ_OFFSET
+value.
+.\" According to the Kernel Application Program Interface document,
+.\" STA_FREQHOLD is not used by the NTP version 4 daemon
+.TP
+.BR STA_PPSSIGNAL " (read-only)"
+A valid PPS (pulse-per-second) signal is present.
+.TP
+.BR STA_PPSJITTER " (read-only)"
+PPS signal jitter exceeded.
+.TP
+.BR STA_PPSWANDER " (read-only)"
+PPS signal wander exceeded.
+.TP
+.BR STA_PPSERROR " (read-only)"
+PPS signal calibration error.
+.TP
+.BR STA_CLOCKERR " (read-only)"
+Clock hardware fault.
+.\" Not set in current kernel (4.5), but checked in a few places
+.TP
+.BR STA_NANO " (read-only; since Linux 2.6.26)"
+.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
+.\" Author: Roman Zippel <zippel@linux-m68k.org>
+Resolution (0 = microsecond, 1 = nanoseconds).
+Set via
+.BR ADJ_NANO ,
+cleared via
+.BR ADJ_MICRO .
+.TP
+.BR STA_MODE " (since Linux 2.6.26)"
+.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
+.\" Author: Roman Zippel <zippel@linux-m68k.org>
+Mode (0 = Phase Locked Loop, 1 = Frequency Locked Loop).
+.TP
+.BR STA_CLK " (read-only; since Linux 2.6.26)"
+.\" commit eea83d896e318bda54be2d2770d2c5d6668d11db
+.\" Author: Roman Zippel <zippel@linux-m68k.org>
+Clock source (0 = A, 1 = B); currently unused.
+.P
+Attempts to set read-only
+.I status
+bits are silently ignored.
+.\"
+.SS clock_adjtime ()
+The
+.BR clock_adjtime ()
+system call (added in Linux 2.6.39) behaves like
+.BR adjtimex ()
+but takes an additional
+.I clk_id
+argument to specify the particular clock on which to act.
+.SS ntp_adjtime ()
+The
+.BR ntp_adjtime ()
+library function
+(described in the NTP "Kernel Application Program API", KAPI)
+is a more portable interface for performing the same task as
+.BR adjtimex ().
+Other than the following points, it is identical to
+.BR adjtimex ():
+.IP \[bu] 3
+The constants used in
+.I modes
+are prefixed with "MOD_" rather than "ADJ_", and have the same suffixes (thus,
+.BR MOD_OFFSET ,
+.BR MOD_FREQUENCY ,
+and so on), other than the exceptions noted in the following points.
+.IP \[bu]
+.B MOD_CLKA
+is the synonym for
+.BR ADJ_OFFSET_SINGLESHOT .
+.IP \[bu]
+.B MOD_CLKB
+is the synonym for
+.BR ADJ_TICK .
+.IP \[bu]
+The is no synonym for
+.BR ADJ_OFFSET_SS_READ ,
+which is not described in the KAPI.
+.SH RETURN VALUE
+On success,
+.BR adjtimex ()
+and
+.BR ntp_adjtime ()
+return the clock state; that is, one of the following values:
+.TP 12
+.B TIME_OK
+Clock synchronized, no leap second adjustment pending.
+.TP
+.B TIME_INS
+Indicates that a leap second will be added at the end of the UTC day.
+.TP
+.B TIME_DEL
+Indicates that a leap second will be deleted at the end of the UTC day.
+.TP
+.B TIME_OOP
+Insertion of a leap second is in progress.
+.TP
+.B TIME_WAIT
+A leap-second insertion or deletion has been completed.
+This value will be returned until the next
+.B ADJ_STATUS
+operation clears the
+.B STA_INS
+and
+.B STA_DEL
+flags.
+.TP
+.B TIME_ERROR
+The system clock is not synchronized to a reliable server.
+This value is returned when any of the following holds true:
+.RS
+.IP \[bu] 3
+Either
+.B STA_UNSYNC
+or
+.B STA_CLOCKERR
+is set.
+.IP \[bu]
+.B STA_PPSSIGNAL
+is clear and either
+.B STA_PPSFREQ
+or
+.B STA_PPSTIME
+is set.
+.IP \[bu]
+.B STA_PPSTIME
+and
+.B STA_PPSJITTER
+are both set.
+.IP \[bu]
+.B STA_PPSFREQ
+is set and either
+.B STA_PPSWANDER
+or
+.B STA_PPSJITTER
+is set.
+.RE
+.IP
+The symbolic name
+.B TIME_BAD
+is a synonym for
+.BR TIME_ERROR ,
+provided for backward compatibility.
+.P
+Note that starting with Linux 3.4,
+.\" commit 6b43ae8a619d17c4935c3320d2ef9e92bdeed05d changed to asynchronous
+.\"  operation, so we can no longer rely on the return code.
+the call operates asynchronously and the return value usually will
+not reflect a state change caused by the call itself.
+.P
+On failure, these calls return \-1 and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I buf
+does not point to writable memory.
+.TP
+.BR EINVAL " (before Linux 2.6.26)"
+An attempt was made to set
+.I buf.freq
+to a value outside the range (\-33554432, +33554432).
+.\" From a quick glance, it appears there was no clamping or range check
+.\" for buf.freq before Linux 2.0
+.TP
+.BR EINVAL " (before Linux 2.6.26)"
+An attempt was made to set
+.I buf.offset
+to a value outside the permitted range.
+Before Linux 2.0, the permitted range was (\-131072, +131072).
+From Linux 2.0 onwards, the permitted range was (\-512000, +512000).
+.TP
+.B EINVAL
+An attempt was made to set
+.I buf.status
+to a value other than those listed above.
+.TP
+.B EINVAL
+The
+.I clk_id
+given to
+.BR clock_adjtime ()
+is invalid for one of two reasons.
+Either the System-V style hard-coded
+positive clock ID value is out of range, or the dynamic
+.I clk_id
+does not refer to a valid instance of a clock object.
+See
+.BR clock_gettime (2)
+for a discussion of dynamic clocks.
+.TP
+.B EINVAL
+An attempt was made to set
+.I buf.tick
+to a value outside the range
+.RB 900000/ HZ
+to
+.RB 1100000/ HZ ,
+where
+.B HZ
+is the system timer interrupt frequency.
+.TP
+.B ENODEV
+The hot-pluggable device (like USB for example) represented by a
+dynamic
+.I clk_id
+has disappeared after its character device was opened.
+See
+.BR clock_gettime (2)
+for a discussion of dynamic clocks.
+.TP
+.B EOPNOTSUPP
+The given
+.I clk_id
+does not support adjustment.
+.TP
+.B EPERM
+.I buf.modes
+is neither 0 nor
+.BR ADJ_OFFSET_SS_READ ,
+and the caller does not have sufficient privilege.
+Under Linux, the
+.B CAP_SYS_TIME
+capability is required.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR \%ntp_adjtime ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR adjtimex ()
+.TQ
+.BR clock_adjtime ()
+Linux.
+.P
+The preferred API for the NTP daemon is
+.BR ntp_adjtime ().
+.SH NOTES
+In struct
+.IR timex ,
+.IR freq ,
+.IR ppsfreq ,
+and
+.I stabil
+are ppm (parts per million) with a 16-bit fractional part,
+which means that a value of 1 in one of those fields
+actually means 2\[ha]-16 ppm, and 2\[ha]16=65536 is 1 ppm.
+This is the case for both input values (in the case of
+.IR freq )
+and output values.
+.P
+The leap-second processing triggered by
+.B STA_INS
+and
+.B STA_DEL
+is done by the kernel in timer context.
+Thus, it will take one tick into the second
+for the leap second to be inserted or deleted.
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR clock_settime (2),
+.BR settimeofday (2),
+.BR adjtime (3),
+.BR ntp_gettime (3),
+.BR capabilities (7),
+.BR time (7),
+.BR adjtimex (8),
+.BR hwclock (8)
+.P
+.ad l
+.UR http://www.slac.stanford.edu/comp/unix/\:package/\:rtems/\:src/\:ssrlApps/\:ntpNanoclock/\:api.htm
+NTP "Kernel Application Program Interface"
+.UE
diff --git a/man/man2/afs_syscall.2 b/man/man2/afs_syscall.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/afs_syscall.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/alarm.2 b/man/man2/alarm.2
new file mode 100644
index 000000000..4a4f0fd37
--- /dev/null
+++ b/man/man2/alarm.2
@@ -0,0 +1,81 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 21 19:42:57 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Jul 21 21:25:26 1996 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Wed Nov  6 03:46:05 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\"
+.TH alarm 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+alarm \- set an alarm clock for delivery of a signal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "unsigned int alarm(unsigned int " seconds );
+.fi
+.SH DESCRIPTION
+.BR alarm ()
+arranges for a
+.B SIGALRM
+signal to be delivered to the calling process in
+.I seconds
+seconds.
+.P
+If
+.I seconds
+is zero, any pending alarm is canceled.
+.P
+In any event any previously set
+.BR alarm ()
+is canceled.
+.SH RETURN VALUE
+.BR alarm ()
+returns the number of seconds remaining until any previously scheduled
+alarm was due to be delivered, or zero if there was no previously
+scheduled alarm.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH NOTES
+.BR alarm ()
+and
+.BR setitimer (2)
+share the same timer; calls to one will interfere with use of the
+other.
+.P
+Alarms created by
+.BR alarm ()
+are preserved across
+.BR execve (2)
+and are not inherited by children created via
+.BR fork (2).
+.P
+.BR sleep (3)
+may be implemented using
+.BR SIGALRM ;
+mixing calls to
+.BR alarm ()
+and
+.BR sleep (3)
+is a bad idea.
+.P
+Scheduling delays can, as ever, cause the execution of the process to
+be delayed by an arbitrary amount of time.
+.SH SEE ALSO
+.BR gettimeofday (2),
+.BR pause (2),
+.BR select (2),
+.BR setitimer (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR timer_create (2),
+.BR timerfd_create (2),
+.BR sleep (3),
+.BR time (7)
diff --git a/man/man2/alloc_hugepages.2 b/man/man2/alloc_hugepages.2
new file mode 100644
index 000000000..8e4b7ee1b
--- /dev/null
+++ b/man/man2/alloc_hugepages.2
@@ -0,0 +1,135 @@
+.\" Copyright 2003 Andries E. Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH alloc_hugepages 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+alloc_hugepages, free_hugepages \- allocate or free huge pages
+.SH SYNOPSIS
+.nf
+.BI "void *syscall(SYS_alloc_hugepages, int " key ", void " addr [. len "], \
+size_t " len ,
+.BI "              int " prot ", int " flag );
+.\" asmlinkage unsigned long sys_alloc_hugepages(int key, unsigned long addr,
+.\" unsigned long len, int prot, int flag);
+.BI "int syscall(SYS_free_hugepages, void *" addr );
+.\" asmlinkage int sys_free_hugepages(unsigned long addr);
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The system calls
+.BR alloc_hugepages ()
+and
+.BR free_hugepages ()
+were introduced in Linux 2.5.36 and removed again in Linux 2.5.54.
+They existed only on i386 and ia64 (when built with
+.BR CONFIG_HUGETLB_PAGE ).
+In Linux 2.4.20, the syscall numbers exist,
+but the calls fail with the error
+.BR ENOSYS .
+.P
+On i386 the memory management hardware knows about ordinary pages (4\ KiB)
+and huge pages (2 or 4\ MiB).
+Similarly ia64 knows about huge pages of
+several sizes.
+These system calls serve to map huge pages into the
+process's memory or to free them again.
+Huge pages are locked into memory, and are not swapped.
+.P
+The
+.I key
+argument is an identifier.
+When zero the pages are private, and
+not inherited by children.
+When positive the pages are shared with other applications using the same
+.IR key ,
+and inherited by child processes.
+.P
+The
+.I addr
+argument of
+.BR free_hugepages ()
+tells which page is being freed: it was the return value of a
+call to
+.BR alloc_hugepages ().
+(The memory is first actually freed when all users have released it.)
+The
+.I addr
+argument of
+.BR alloc_hugepages ()
+is a hint, that the kernel may or may not follow.
+Addresses must be properly aligned.
+.P
+The
+.I len
+argument is the length of the required segment.
+It must be a multiple of the huge page size.
+.P
+The
+.I prot
+argument specifies the memory protection of the segment.
+It is one of
+.BR PROT_READ ,
+.BR PROT_WRITE ,
+.BR PROT_EXEC .
+.P
+The
+.I flag
+argument is ignored, unless
+.I key
+is positive.
+In that case, if
+.I flag
+is
+.BR IPC_CREAT ,
+then a new huge page segment is created when none
+with the given key existed.
+If this flag is not set, then
+.B ENOENT
+is returned when no segment with the given key exists.
+.SH RETURN VALUE
+On success,
+.BR alloc_hugepages ()
+returns the allocated virtual address, and
+.BR free_hugepages ()
+returns zero.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOSYS
+The system call is not supported on this kernel.
+.SH FILES
+.TP
+.I /proc/sys/vm/nr_hugepages
+Number of configured hugetlb pages.
+This can be read and written.
+.TP
+.I /proc/meminfo
+Gives info on the number of configured hugetlb pages and on their size
+in the three variables HugePages_Total, HugePages_Free, Hugepagesize.
+.SH STANDARDS
+Linux on Intel processors.
+.SH HISTORY
+These system calls are gone;
+they existed only in Linux 2.5.36 through to Linux 2.5.54.
+.SH NOTES
+Now the hugetlbfs filesystem can be used instead.
+Memory backed by huge pages (if the CPU supports them) is obtained by
+using
+.BR mmap (2)
+to map files in this virtual filesystem.
+.P
+The maximal number of huge pages can be specified using the
+.B hugepages=
+boot parameter.
+.\".P
+.\" requires CONFIG_HUGETLB_PAGE (under "Processor type and features")
+.\" and CONFIG_HUGETLBFS (under "Filesystems").
+.\" mount \-t hugetlbfs hugetlbfs /huge
+.\" SHM_HUGETLB
diff --git a/man/man2/arch_prctl.2 b/man/man2/arch_prctl.2
new file mode 100644
index 000000000..680d36395
--- /dev/null
+++ b/man/man2/arch_prctl.2
@@ -0,0 +1,176 @@
+.\" Copyright (C) 2003 Andi Kleen
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH arch_prctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+arch_prctl \- set architecture-specific thread state
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <asm/prctl.h>" "        /* Definition of " ARCH_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_arch_prctl, int " op ", unsigned long " addr );
+.BI "int syscall(SYS_arch_prctl, int " op ", unsigned long *" addr );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR arch_prctl (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR arch_prctl ()
+sets architecture-specific process or thread state.
+.I op
+selects an operation
+and passes argument
+.I addr
+to it;
+.I addr
+is interpreted as either an
+.I "unsigned long"
+for the "set" operations, or as an
+.IR "unsigned long\ *" ,
+for the "get" operations.
+.P
+Subfunctions for both x86 and x86-64 are:
+.TP
+.BR ARCH_SET_CPUID " (since Linux 4.12)"
+.\" commit e9ea1e7f53b852147cbd568b0568c7ad97ec21a3
+Enable
+.RI ( "addr != 0" )
+or disable
+.RI ( "addr == 0" )
+the
+.I cpuid
+instruction for the calling thread.
+The instruction is enabled by default.
+If disabled, any execution of a
+.I cpuid
+instruction will instead generate a
+.B SIGSEGV
+signal.
+This feature can be used to emulate
+.I cpuid
+results that differ from what the underlying
+hardware would have produced (e.g., in a paravirtualization setting).
+.IP
+The
+.B ARCH_SET_CPUID
+setting is preserved across
+.BR fork (2)
+and
+.BR clone (2)
+but reset to the default (i.e.,
+.I cpuid
+enabled) on
+.BR execve (2).
+.TP
+.BR ARCH_GET_CPUID " (since Linux 4.12)"
+Return the setting of the flag manipulated by
+.B ARCH_SET_CPUID
+as the result of the system call (1 for enabled, 0 for disabled).
+.I addr
+is ignored.
+.TP
+Subfunctions for x86-64 only are:
+.TP
+.B ARCH_SET_FS
+Set the 64-bit base for the
+.I FS
+register to
+.IR addr .
+.TP
+.B ARCH_GET_FS
+Return the 64-bit base value for the
+.I FS
+register of the calling thread in the
+.I unsigned long
+pointed to by
+.IR addr .
+.TP
+.B ARCH_SET_GS
+Set the 64-bit base for the
+.I GS
+register to
+.IR addr .
+.TP
+.B ARCH_GET_GS
+Return the 64-bit base value for the
+.I GS
+register of the calling thread in the
+.I unsigned long
+pointed to by
+.IR addr .
+.SH RETURN VALUE
+On success,
+.BR arch_prctl ()
+returns 0; on error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I addr
+points to an unmapped address or is outside the process address space.
+.TP
+.B EINVAL
+.I op
+is not a valid operation.
+.TP
+.B ENODEV
+.B ARCH_SET_CPUID
+was requested, but the underlying hardware does not support CPUID faulting.
+.TP
+.B EPERM
+.I addr
+is outside the process address space.
+.\" .SH AUTHOR
+.\" Man page written by Andi Kleen.
+.SH STANDARDS
+Linux/x86-64.
+.SH NOTES
+.BR arch_prctl ()
+is supported only on Linux/x86-64 for 64-bit programs currently.
+.P
+The 64-bit base changes when a new 32-bit segment selector is loaded.
+.P
+.B ARCH_SET_GS
+is disabled in some kernels.
+.P
+Context switches for 64-bit segment bases are rather expensive.
+As an optimization, if a 32-bit TLS base address is used,
+.BR arch_prctl ()
+may use a real TLS entry as if
+.BR set_thread_area (2)
+had been called, instead of manipulating the segment base register directly.
+Memory in the first 2\ GB of address space can be allocated by using
+.BR mmap (2)
+with the
+.B MAP_32BIT
+flag.
+.P
+Because of the aforementioned optimization, using
+.BR arch_prctl ()
+and
+.BR set_thread_area (2)
+in the same thread is dangerous, as they may overwrite each other's
+TLS entries.
+.P
+.I FS
+may be already used by the threading library.
+Programs that use
+.B ARCH_SET_FS
+directly are very likely to crash.
+.SH SEE ALSO
+.BR mmap (2),
+.BR modify_ldt (2),
+.BR prctl (2),
+.BR set_thread_area (2)
+.P
+AMD X86-64 Programmer's manual
diff --git a/man/man2/arm_fadvise.2 b/man/man2/arm_fadvise.2
new file mode 100644
index 000000000..53f54a121
--- /dev/null
+++ b/man/man2/arm_fadvise.2
@@ -0,0 +1 @@
+.so man2/posix_fadvise.2
diff --git a/man/man2/arm_fadvise64_64.2 b/man/man2/arm_fadvise64_64.2
new file mode 100644
index 000000000..53f54a121
--- /dev/null
+++ b/man/man2/arm_fadvise64_64.2
@@ -0,0 +1 @@
+.so man2/posix_fadvise.2
diff --git a/man/man2/arm_sync_file_range.2 b/man/man2/arm_sync_file_range.2
new file mode 100644
index 000000000..ad7a1e6c7
--- /dev/null
+++ b/man/man2/arm_sync_file_range.2
@@ -0,0 +1 @@
+.so man2/sync_file_range.2
diff --git a/man/man2/bdflush.2 b/man/man2/bdflush.2
new file mode 100644
index 000000000..8627a42a2
--- /dev/null
+++ b/man/man2/bdflush.2
@@ -0,0 +1,103 @@
+.\" Copyright (c) 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH bdflush 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bdflush \- start, flush, or tune buffer-dirty-flush daemon
+.SH SYNOPSIS
+.nf
+.B #include <sys/kdaemon.h>
+.P
+.BI "[[deprecated]] int bdflush(int "  func ", long *" address );
+.BI "[[deprecated]] int bdflush(int "  func ", long " data );
+.fi
+.SH DESCRIPTION
+.IR Note :
+Since Linux 2.6,
+.\" As noted in changes in the 2.5.12 source
+this system call is deprecated and does nothing.
+It is likely to disappear altogether in a future kernel release.
+Nowadays, the task performed by
+.BR bdflush ()
+is handled by the kernel
+.I pdflush
+thread.
+.P
+.BR bdflush ()
+starts, flushes, or tunes the buffer-dirty-flush daemon.
+Only a privileged process (one with the
+.B CAP_SYS_ADMIN
+capability) may call
+.BR bdflush ().
+.P
+If
+.I func
+is negative or 0, and no daemon has been started, then
+.BR bdflush ()
+enters the daemon code and never returns.
+.P
+If
+.I func
+is 1,
+some dirty buffers are written to disk.
+.P
+If
+.I func
+is 2 or more and is even (low bit is 0), then
+.I address
+is the address of a long word,
+and the tuning parameter numbered
+.RI "(" "func" "\-2)/2"
+is returned to the caller in that address.
+.P
+If
+.I func
+is 3 or more and is odd (low bit is 1), then
+.I data
+is a long word,
+and the kernel sets tuning parameter numbered
+.RI "(" "func" "\-3)/2"
+to that value.
+.P
+The set of parameters, their values, and their valid ranges
+are defined in the Linux kernel source file
+.IR fs/buffer.c .
+.SH RETURN VALUE
+If
+.I func
+is negative or 0 and the daemon successfully starts,
+.BR bdflush ()
+never returns.
+Otherwise, the return value is 0 on success and \-1 on failure, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EBUSY
+An attempt was made to enter the daemon code after
+another process has already entered.
+.TP
+.B EFAULT
+.I address
+points outside your accessible address space.
+.TP
+.B EINVAL
+An attempt was made to read or write an invalid parameter number,
+or to write an invalid value to a parameter.
+.TP
+.B EPERM
+Caller does not have the
+.B CAP_SYS_ADMIN
+capability.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Since glibc 2.23, glibc no longer supports this obsolete system call.
+.SH SEE ALSO
+.BR sync (1),
+.BR fsync (2),
+.BR sync (2)
diff --git a/man/man2/bind.2 b/man/man2/bind.2
new file mode 100644
index 000000000..2fec135d9
--- /dev/null
+++ b/man/man2/bind.2
@@ -0,0 +1,286 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\" and Copyright 2005-2007, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Portions extracted from /usr/include/sys/socket.h, which does not have
+.\" any authorship information in it.  It is probably available under the GPL.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.\" Other portions are from the 6.9 (Berkeley) 3/10/91 man page:
+.\"
+.\" Copyright (c) 1983 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" Modified Mon Oct 21 23:05:29 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998 by Andi Kleen
+.\" $Id: bind.2,v 1.3 1999/04/23 19:56:07 freitag Exp $
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH bind 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bind \- bind a name to a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int bind(int " sockfd ", const struct sockaddr *" addr ,
+.BI "         socklen_t " addrlen );
+.fi
+.SH DESCRIPTION
+When a socket is created with
+.BR socket (2),
+it exists in a name space (address family) but has no address assigned to it.
+.BR bind ()
+assigns the address specified by
+.I addr
+to the socket referred to by the file descriptor
+.IR sockfd .
+.I addrlen
+specifies the size, in bytes, of the address structure pointed to by
+.IR addr .
+Traditionally, this operation is called \[lq]assigning a name to a socket\[rq].
+.P
+It is normally necessary to assign a local address using
+.BR bind ()
+before a
+.B SOCK_STREAM
+socket may receive connections (see
+.BR accept (2)).
+.P
+The rules used in name binding vary between address families.
+Consult the manual entries in Section 7 for detailed information.
+For
+.BR AF_INET ,
+see
+.BR ip (7);
+for
+.BR AF_INET6 ,
+see
+.BR ipv6 (7);
+for
+.BR AF_UNIX ,
+see
+.BR unix (7);
+for
+.BR AF_APPLETALK ,
+see
+.BR ddp (7);
+for
+.BR AF_PACKET ,
+see
+.BR packet (7);
+for
+.BR AF_X25 ,
+see
+.BR x25 (7);
+and for
+.BR AF_NETLINK ,
+see
+.BR netlink (7).
+.P
+The actual structure passed for the
+.I addr
+argument will depend on the address family.
+The
+.I sockaddr
+structure is defined as something like:
+.P
+.in +4n
+.EX
+struct sockaddr {
+    sa_family_t sa_family;
+    char        sa_data[14];
+}
+.EE
+.in
+.P
+The only purpose of this structure is to cast the structure
+pointer passed in
+.I addr
+in order to avoid compiler warnings.
+See EXAMPLES below.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.\" e.g., privileged port in AF_INET domain
+The address is protected, and the user is not the superuser.
+.TP
+.B EADDRINUSE
+The given address is already in use.
+.TP
+.B EADDRINUSE
+(Internet domain sockets)
+The port number was specified as zero in the socket address structure,
+but, upon attempting to bind to an ephemeral port,
+it was determined that all port numbers in the ephemeral port range
+are currently in use.
+See the discussion of
+.I /proc/sys/net/ipv4/ip_local_port_range
+.BR ip (7).
+.TP
+.B EBADF
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+The socket is already bound to an address.
+.\" This may change in the future: see
+.\" .I linux/unix/sock.c for details.
+.TP
+.B EINVAL
+.I addrlen
+is wrong, or
+.I addr
+is not a valid address for this socket's domain.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.P
+The following errors are specific to UNIX domain
+.RB ( AF_UNIX )
+sockets:
+.TP
+.B EACCES
+Search permission is denied on a component of the path prefix.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EADDRNOTAVAIL
+A nonexistent interface was requested or the requested
+address was not local.
+.TP
+.B EFAULT
+.I addr
+points outside the user's accessible address space.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR addr .
+.TP
+.B ENAMETOOLONG
+.I addr
+is too long.
+.TP
+.B ENOENT
+A component in the directory prefix of the socket pathname does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of the path prefix is not a directory.
+.TP
+.B EROFS
+The socket inode would reside on a read-only filesystem.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD
+.RB ( bind ()
+first appeared in 4.2BSD).
+.\" SVr4 documents an additional
+.\" .B ENOSR
+.\" general error condition, and
+.\" additional
+.\" .B EIO
+.\" and
+.\" .B EISDIR
+.\" UNIX-domain error conditions.
+.SH BUGS
+The transparent proxy options are not described.
+.\" FIXME Document transparent proxy options
+.SH EXAMPLES
+An example of the use of
+.BR bind ()
+with Internet domain sockets can be found in
+.BR getaddrinfo (3).
+.P
+The following example shows how to bind a stream socket in the UNIX
+.RB ( AF_UNIX )
+domain, and accept connections:
+.\" listen.7 refers to this example.
+.\" accept.7 refers to this example.
+.\" unix.7 refers to this example.
+.P
+.\" SRC BEGIN (bind.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+\&
+#define MY_SOCK_PATH "/somepath"
+#define LISTEN_BACKLOG 50
+\&
+#define handle_error(msg) \e
+    do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+int
+main(void)
+{
+    int                 sfd, cfd;
+    socklen_t           peer_addr_size;
+    struct sockaddr_un  my_addr, peer_addr;
+\&
+    sfd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (sfd == \-1)
+        handle_error("socket");
+\&
+    memset(&my_addr, 0, sizeof(my_addr));
+    my_addr.sun_family = AF_UNIX;
+    strncpy(my_addr.sun_path, MY_SOCK_PATH,
+            sizeof(my_addr.sun_path) \- 1);
+\&
+    if (bind(sfd, (struct sockaddr *) &my_addr,
+             sizeof(my_addr)) == \-1)
+        handle_error("bind");
+\&
+    if (listen(sfd, LISTEN_BACKLOG) == \-1)
+        handle_error("listen");
+\&
+    /* Now we can accept incoming connections one
+       at a time using accept(2). */
+\&
+    peer_addr_size = sizeof(peer_addr);
+    cfd = accept(sfd, (struct sockaddr *) &peer_addr,
+                 &peer_addr_size);
+    if (cfd == \-1)
+        handle_error("accept");
+\&
+    /* Code to deal with incoming connection(s)... */
+\&
+    if (close(sfd) == \-1)
+        handle_error("close");
+\&
+    if (unlink(MY_SOCK_PATH) == \-1)
+        handle_error("unlink");
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR accept (2),
+.BR connect (2),
+.BR getsockname (2),
+.BR listen (2),
+.BR socket (2),
+.BR getaddrinfo (3),
+.BR getifaddrs (3),
+.BR ip (7),
+.BR ipv6 (7),
+.BR path_resolution (7),
+.BR socket (7),
+.BR unix (7)
diff --git a/man/man2/bpf.2 b/man/man2/bpf.2
new file mode 100644
index 000000000..69e1cd933
--- /dev/null
+++ b/man/man2/bpf.2
@@ -0,0 +1,1273 @@
+.\" Copyright (C) 2015 Alexei Starovoitov <ast@kernel.org>
+.\" and Copyright (C) 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH bpf 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bpf \- perform a command on an extended BPF map or program
+.SH SYNOPSIS
+.nf
+.B #include <linux/bpf.h>
+.P
+.BI "int bpf(int " cmd ", union bpf_attr *" attr ", unsigned int " size );
+.fi
+.SH DESCRIPTION
+The
+.BR bpf ()
+system call performs a range of operations related to extended
+Berkeley Packet Filters.
+Extended BPF (or eBPF) is similar to
+the original ("classic") BPF (cBPF) used to filter network packets.
+For both cBPF and eBPF programs,
+the kernel statically analyzes the programs before loading them,
+in order to ensure that they cannot harm the running system.
+.P
+eBPF extends cBPF in multiple ways, including the ability to call
+a fixed set of in-kernel helper functions
+.\" See 'enum bpf_func_id' in include/uapi/linux/bpf.h
+(via the
+.B BPF_CALL
+opcode extension provided by eBPF)
+and access shared data structures such as eBPF maps.
+.\"
+.SS Extended BPF Design/Architecture
+eBPF maps are a generic data structure for storage of different data types.
+Data types are generally treated as binary blobs, so a user just specifies
+the size of the key and the size of the value at map-creation time.
+In other words, a key/value for a given map can have an arbitrary structure.
+.P
+A user process can create multiple maps (with key/value-pairs being
+opaque bytes of data) and access them via file descriptors.
+Different eBPF programs can access the same maps in parallel.
+It's up to the user process and eBPF program to decide what they store
+inside maps.
+.P
+There's one special map type, called a program array.
+This type of map stores file descriptors referring to other eBPF programs.
+When a lookup in the map is performed, the program flow is
+redirected in-place to the beginning of another eBPF program and does not
+return back to the calling program.
+The level of nesting has a fixed limit of 32,
+.\" Defined by the kernel constant MAX_TAIL_CALL_CNT in include/linux/bpf.h
+so that infinite loops cannot be crafted.
+At run time, the program file descriptors stored in the map can be modified,
+so program functionality can be altered based on specific requirements.
+All programs referred to in a program-array map must
+have been previously loaded into the kernel via
+.BR bpf ().
+If a map lookup fails, the current program continues its execution.
+See
+.B BPF_MAP_TYPE_PROG_ARRAY
+below for further details.
+.P
+Generally, eBPF programs are loaded by the user process and automatically
+unloaded when the process exits.
+In some cases, for example,
+.BR tc\-bpf (8),
+the program will continue to stay alive inside the kernel even after the
+process that loaded the program exits.
+In that case,
+the tc subsystem holds a reference to the eBPF program after the
+file descriptor has been closed by the user-space program.
+Thus, whether a specific program continues to live inside the kernel
+depends on how it is further attached to a given kernel subsystem
+after it was loaded via
+.BR bpf ().
+.P
+Each eBPF program is a set of instructions that is safe to run until
+its completion.
+An in-kernel verifier statically determines that the eBPF program
+terminates and is safe to execute.
+During verification, the kernel increments reference counts for each of
+the maps that the eBPF program uses,
+so that the attached maps can't be removed until the program is unloaded.
+.P
+eBPF programs can be attached to different events.
+These events can be the arrival of network packets, tracing
+events, classification events by network queueing  disciplines
+(for eBPF programs attached to a
+.BR tc (8)
+classifier), and other types that may be added in the future.
+A new event triggers execution of the eBPF program, which
+may store information about the event in eBPF maps.
+Beyond storing data, eBPF programs may call a fixed set of
+in-kernel helper functions.
+.P
+The same eBPF program can be attached to multiple events and different
+eBPF programs can access the same map:
+.P
+.in +4n
+.EX
+tracing     tracing    tracing    packet      packet     packet
+event A     event B    event C    on eth0     on eth1    on eth2
+ |             |         |          |           |          \[ha]
+ |             |         |          |           v          |
+ \-\-> tracing <\-\-     tracing      socket    tc ingress   tc egress
+      prog_1          prog_2      prog_3    classifier    action
+      |  |              |           |         prog_4      prog_5
+   |\-\-\-  \-\-\-\-\-|  |\-\-\-\-\-\-|          map_3        |           |
+ map_1       map_2                              \-\-| map_4 |\-\-
+.EE
+.in
+.\"
+.SS Arguments
+The operation to be performed by the
+.BR bpf ()
+system call is determined by the
+.I cmd
+argument.
+Each operation takes an accompanying argument,
+provided via
+.IR attr ,
+which is a pointer to a union of type
+.I bpf_attr
+(see below).
+The unused fields and padding must be zeroed out before the call.
+The
+.I size
+argument is the size of the union pointed to by
+.IR attr .
+.P
+The value provided in
+.I cmd
+is one of the following:
+.TP
+.B BPF_MAP_CREATE
+Create a map and return a file descriptor that refers to the map.
+The close-on-exec file descriptor flag (see
+.BR fcntl (2))
+is automatically enabled for the new file descriptor.
+.TP
+.B BPF_MAP_LOOKUP_ELEM
+Look up an element by key in a specified map and return its value.
+.TP
+.B BPF_MAP_UPDATE_ELEM
+Create or update an element (key/value pair) in a specified map.
+.TP
+.B BPF_MAP_DELETE_ELEM
+Look up and delete an element by key in a specified map.
+.TP
+.B BPF_MAP_GET_NEXT_KEY
+Look up an element by key in a specified map and return the key
+of the next element.
+.TP
+.B BPF_PROG_LOAD
+Verify and load an eBPF program,
+returning a new file descriptor associated with the program.
+The close-on-exec file descriptor flag (see
+.BR fcntl (2))
+is automatically enabled for the new file descriptor.
+.IP
+The
+.I bpf_attr
+union consists of various anonymous structures that are used by different
+.BR bpf ()
+commands:
+.P
+.in +4n
+.EX
+union bpf_attr {
+    struct {    /* Used by BPF_MAP_CREATE */
+        __u32         map_type;
+        __u32         key_size;    /* size of key in bytes */
+        __u32         value_size;  /* size of value in bytes */
+        __u32         max_entries; /* maximum number of entries
+                                      in a map */
+    };
+\&
+    struct {    /* Used by BPF_MAP_*_ELEM and BPF_MAP_GET_NEXT_KEY
+                   commands */
+        __u32         map_fd;
+        __aligned_u64 key;
+        union {
+            __aligned_u64 value;
+            __aligned_u64 next_key;
+        };
+        __u64         flags;
+    };
+\&
+    struct {    /* Used by BPF_PROG_LOAD */
+        __u32         prog_type;
+        __u32         insn_cnt;
+        __aligned_u64 insns;      /* \[aq]const struct bpf_insn *\[aq] */
+        __aligned_u64 license;    /* \[aq]const char *\[aq] */
+        __u32         log_level;  /* verbosity level of verifier */
+        __u32         log_size;   /* size of user buffer */
+        __aligned_u64 log_buf;    /* user supplied \[aq]char *\[aq]
+                                     buffer */
+        __u32         kern_version;
+                                  /* checked when prog_type=kprobe
+                                     (since Linux 4.1) */
+.\"                 commit 2541517c32be2531e0da59dfd7efc1ce844644f5
+    };
+} __attribute__((aligned(8)));
+.EE
+.in
+.\"
+.SS eBPF maps
+Maps are a generic data structure for storage of different types of data.
+They allow sharing of data between eBPF kernel programs,
+and also between kernel and user-space applications.
+.P
+Each map type has the following attributes:
+.IP \[bu] 3
+type
+.IP \[bu]
+maximum number of elements
+.IP \[bu]
+key size in bytes
+.IP \[bu]
+value size in bytes
+.P
+The following wrapper functions demonstrate how various
+.BR bpf ()
+commands can be used to access the maps.
+The functions use the
+.I cmd
+argument to invoke different operations.
+.TP
+.B BPF_MAP_CREATE
+The
+.B BPF_MAP_CREATE
+command creates a new map,
+returning a new file descriptor that refers to the map.
+.IP
+.in +4n
+.EX
+int
+bpf_create_map(enum bpf_map_type map_type,
+               unsigned int key_size,
+               unsigned int value_size,
+               unsigned int max_entries)
+{
+    union bpf_attr attr = {
+        .map_type    = map_type,
+        .key_size    = key_size,
+        .value_size  = value_size,
+        .max_entries = max_entries
+    };
+\&
+    return bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
+}
+.EE
+.in
+.IP
+The new map has the type specified by
+.IR map_type ,
+and attributes as specified in
+.IR key_size ,
+.IR value_size ,
+and
+.IR max_entries .
+On success, this operation returns a file descriptor.
+On error, \-1 is returned and
+.I errno
+is set to
+.BR EINVAL ,
+.BR EPERM ,
+or
+.BR ENOMEM .
+.IP
+The
+.I key_size
+and
+.I value_size
+attributes will be used by the verifier during program loading
+to check that the program is calling
+.BR bpf_map_*_elem ()
+helper functions with a correctly initialized
+.I key
+and to check that the program doesn't access the map element
+.I value
+beyond the specified
+.IR value_size .
+For example, when a map is created with a
+.I key_size
+of 8 and the eBPF program calls
+.IP
+.in +4n
+.EX
+bpf_map_lookup_elem(map_fd, fp \- 4)
+.EE
+.in
+.IP
+the program will be rejected,
+since the in-kernel helper function
+.IP
+.in +4n
+.EX
+bpf_map_lookup_elem(map_fd, void *key)
+.EE
+.in
+.IP
+expects to read 8 bytes from the location pointed to by
+.IR key ,
+but the
+.I fp\ \-\ 4
+(where
+.I fp
+is the top of the stack)
+starting address will cause out-of-bounds stack access.
+.IP
+Similarly, when a map is created with a
+.I value_size
+of 1 and the eBPF program contains
+.IP
+.in +4n
+.EX
+value = bpf_map_lookup_elem(...);
+*(u32 *) value = 1;
+.EE
+.in
+.IP
+the program will be rejected, since it accesses the
+.I value
+pointer beyond the specified 1 byte
+.I value_size
+limit.
+.IP
+Currently, the following values are supported for
+.IR map_type :
+.IP
+.in +4n
+.EX
+enum bpf_map_type {
+    BPF_MAP_TYPE_UNSPEC,  /* Reserve 0 as invalid map type */
+    BPF_MAP_TYPE_HASH,
+    BPF_MAP_TYPE_ARRAY,
+    BPF_MAP_TYPE_PROG_ARRAY,
+    BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+    BPF_MAP_TYPE_PERCPU_HASH,
+    BPF_MAP_TYPE_PERCPU_ARRAY,
+    BPF_MAP_TYPE_STACK_TRACE,
+    BPF_MAP_TYPE_CGROUP_ARRAY,
+    BPF_MAP_TYPE_LRU_HASH,
+    BPF_MAP_TYPE_LRU_PERCPU_HASH,
+    BPF_MAP_TYPE_LPM_TRIE,
+    BPF_MAP_TYPE_ARRAY_OF_MAPS,
+    BPF_MAP_TYPE_HASH_OF_MAPS,
+    BPF_MAP_TYPE_DEVMAP,
+    BPF_MAP_TYPE_SOCKMAP,
+    BPF_MAP_TYPE_CPUMAP,
+    BPF_MAP_TYPE_XSKMAP,
+    BPF_MAP_TYPE_SOCKHASH,
+    BPF_MAP_TYPE_CGROUP_STORAGE,
+    BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
+    BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
+    BPF_MAP_TYPE_QUEUE,
+    BPF_MAP_TYPE_STACK,
+    /* See /usr/include/linux/bpf.h for the full list. */
+};
+.EE
+.in
+.IP
+.I map_type
+selects one of the available map implementations in the kernel.
+.\" FIXME We need an explanation of why one might choose each of
+.\" these map implementations
+For all map types,
+eBPF programs access maps with the same
+.BR bpf_map_lookup_elem ()
+and
+.BR bpf_map_update_elem ()
+helper functions.
+Further details of the various map types are given below.
+.TP
+.B BPF_MAP_LOOKUP_ELEM
+The
+.B BPF_MAP_LOOKUP_ELEM
+command looks up an element with a given
+.I key
+in the map referred to by the file descriptor
+.IR fd .
+.IP
+.in +4n
+.EX
+int
+bpf_lookup_elem(int fd, const void *key, void *value)
+{
+    union bpf_attr attr = {
+        .map_fd = fd,
+        .key    = ptr_to_u64(key),
+        .value  = ptr_to_u64(value),
+    };
+\&
+    return bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+}
+.EE
+.in
+.IP
+If an element is found,
+the operation returns zero and stores the element's value into
+.IR value ,
+which must point to a buffer of
+.I value_size
+bytes.
+.IP
+If no element is found, the operation returns \-1 and sets
+.I errno
+to
+.BR ENOENT .
+.TP
+.B BPF_MAP_UPDATE_ELEM
+The
+.B BPF_MAP_UPDATE_ELEM
+command
+creates or updates an element with a given
+.I key/value
+in the map referred to by the file descriptor
+.IR fd .
+.IP
+.in +4n
+.EX
+int
+bpf_update_elem(int fd, const void *key, const void *value,
+                uint64_t flags)
+{
+    union bpf_attr attr = {
+        .map_fd = fd,
+        .key    = ptr_to_u64(key),
+        .value  = ptr_to_u64(value),
+        .flags  = flags,
+    };
+\&
+    return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
+}
+.EE
+.in
+.IP
+The
+.I flags
+argument should be specified as one of the following:
+.RS
+.TP
+.B BPF_ANY
+Create a new element or update an existing element.
+.TP
+.B BPF_NOEXIST
+Create a new element only if it did not exist.
+.TP
+.B BPF_EXIST
+Update an existing element.
+.RE
+.IP
+On success, the operation returns zero.
+On error, \-1 is returned and
+.I errno
+is set to
+.BR EINVAL ,
+.BR EPERM ,
+.BR ENOMEM ,
+or
+.BR E2BIG .
+.B E2BIG
+indicates that the number of elements in the map reached the
+.I max_entries
+limit specified at map creation time.
+.B EEXIST
+will be returned if
+.I flags
+specifies
+.B BPF_NOEXIST
+and the element with
+.I key
+already exists in the map.
+.B ENOENT
+will be returned if
+.I flags
+specifies
+.B BPF_EXIST
+and the element with
+.I key
+doesn't exist in the map.
+.TP
+.B BPF_MAP_DELETE_ELEM
+The
+.B BPF_MAP_DELETE_ELEM
+command
+deletes the element whose key is
+.I key
+from the map referred to by the file descriptor
+.IR fd .
+.IP
+.in +4n
+.EX
+int
+bpf_delete_elem(int fd, const void *key)
+{
+    union bpf_attr attr = {
+        .map_fd = fd,
+        .key    = ptr_to_u64(key),
+    };
+\&
+    return bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
+}
+.EE
+.in
+.IP
+On success, zero is returned.
+If the element is not found, \-1 is returned and
+.I errno
+is set to
+.BR ENOENT .
+.TP
+.B BPF_MAP_GET_NEXT_KEY
+The
+.B BPF_MAP_GET_NEXT_KEY
+command looks up an element by
+.I key
+in the map referred to by the file descriptor
+.I fd
+and sets the
+.I next_key
+pointer to the key of the next element.
+.IP
+.in +4n
+.EX
+int
+bpf_get_next_key(int fd, const void *key, void *next_key)
+{
+    union bpf_attr attr = {
+        .map_fd   = fd,
+        .key      = ptr_to_u64(key),
+        .next_key = ptr_to_u64(next_key),
+    };
+\&
+    return bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
+}
+.EE
+.in
+.IP
+If
+.I key
+is found, the operation returns zero and sets the
+.I next_key
+pointer to the key of the next element.
+If
+.I key
+is not found, the operation returns zero and sets the
+.I next_key
+pointer to the key of the first element.
+If
+.I key
+is the last element, \-1 is returned and
+.I errno
+is set to
+.BR ENOENT .
+Other possible
+.I errno
+values are
+.BR ENOMEM ,
+.BR EFAULT ,
+.BR EPERM ,
+and
+.BR EINVAL .
+This method can be used to iterate over all elements in the map.
+.TP
+.B close(map_fd)
+Delete the map referred to by the file descriptor
+.IR map_fd .
+When the user-space program that created a map exits, all maps will
+be deleted automatically (but see NOTES).
+.\"
+.SS eBPF map types
+The following map types are supported:
+.TP
+.B BPF_MAP_TYPE_HASH
+.\" commit 0f8e4bd8a1fc8c4185f1630061d0a1f2d197a475
+Hash-table maps have the following characteristics:
+.RS
+.IP \[bu] 3
+Maps are created and destroyed by user-space programs.
+Both user-space and eBPF programs
+can perform lookup, update, and delete operations.
+.IP \[bu]
+The kernel takes care of allocating and freeing key/value pairs.
+.IP \[bu]
+The
+.BR map_update_elem ()
+helper will fail to insert new element when the
+.I max_entries
+limit is reached.
+(This ensures that eBPF programs cannot exhaust memory.)
+.IP \[bu]
+.BR map_update_elem ()
+replaces existing elements atomically.
+.RE
+.IP
+Hash-table maps are
+optimized for speed of lookup.
+.TP
+.B BPF_MAP_TYPE_ARRAY
+.\" commit 28fbcfa08d8ed7c5a50d41a0433aad222835e8e3
+Array maps have the following characteristics:
+.RS
+.IP \[bu] 3
+Optimized for fastest possible lookup.
+In the future the verifier/JIT compiler
+may recognize lookup() operations that employ a constant key
+and optimize it into constant pointer.
+It is possible to optimize a non-constant
+key into direct pointer arithmetic as well, since pointers and
+.I value_size
+are constant for the life of the eBPF program.
+In other words,
+.BR array_map_lookup_elem ()
+may be 'inlined' by the verifier/JIT compiler
+while preserving concurrent access to this map from user space.
+.IP \[bu]
+All array elements pre-allocated and zero initialized at init time
+.IP \[bu]
+The key is an array index, and must be exactly four bytes.
+.IP \[bu]
+.BR map_delete_elem ()
+fails with the error
+.BR EINVAL ,
+since elements cannot be deleted.
+.IP \[bu]
+.BR map_update_elem ()
+replaces elements in a
+.B nonatomic
+fashion;
+for atomic updates, a hash-table map should be used instead.
+There is however one special case that can also be used with arrays:
+the atomic built-in
+.B __sync_fetch_and_add()
+can be used on 32 and 64 bit atomic counters.
+For example, it can be
+applied on the whole value itself if it represents a single counter,
+or in case of a structure containing multiple counters, it could be
+used on individual counters.
+This is quite often useful for aggregation and accounting of events.
+.RE
+.IP
+Among the uses for array maps are the following:
+.RS
+.IP \[bu] 3
+As "global" eBPF variables: an array of 1 element whose key is (index) 0
+and where the value is a collection of 'global' variables which
+eBPF programs can use to keep state between events.
+.IP \[bu]
+Aggregation of tracing events into a fixed set of buckets.
+.IP \[bu]
+Accounting of networking events, for example, number of packets and packet
+sizes.
+.RE
+.TP
+.BR BPF_MAP_TYPE_PROG_ARRAY " (since Linux 4.2)"
+A program array map is a special kind of array map whose map values
+contain only file descriptors referring to other eBPF programs.
+Thus, both the
+.I key_size
+and
+.I value_size
+must be exactly four bytes.
+This map is used in conjunction with the
+.BR bpf_tail_call ()
+helper.
+.IP
+This means that an eBPF program with a program array map attached to it
+can call from kernel side into
+.IP
+.in +4n
+.EX
+void bpf_tail_call(void *context, void *prog_map,
+                   unsigned int index);
+.EE
+.in
+.IP
+and therefore replace its own program flow with the one from the program
+at the given program array slot, if present.
+This can be regarded as kind of a jump table to a different eBPF program.
+The invoked program will then reuse the same stack.
+When a jump into the new program has been performed,
+it won't return to the old program anymore.
+.IP
+If no eBPF program is found at the given index of the program array
+(because the map slot doesn't contain a valid program file descriptor,
+the specified lookup index/key is out of bounds,
+or the limit of 32
+.\" MAX_TAIL_CALL_CNT
+nested calls has been exceed),
+execution continues with the current eBPF program.
+This can be used as a fall-through for default cases.
+.IP
+A program array map is useful, for example, in tracing or networking, to
+handle individual system calls or protocols in their own subprograms and
+use their identifiers as an individual map index.
+This approach may result in performance benefits,
+and also makes it possible to overcome the maximum
+instruction limit of a single eBPF program.
+In dynamic environments,
+a user-space daemon might atomically replace individual subprograms
+at run-time with newer versions to alter overall program behavior,
+for instance, if global policies change.
+.\"
+.SS eBPF programs
+The
+.B BPF_PROG_LOAD
+command is used to load an eBPF program into the kernel.
+The return value for this command is a new file descriptor associated
+with this eBPF program.
+.P
+.in +4n
+.EX
+char bpf_log_buf[LOG_BUF_SIZE];
+\&
+int
+bpf_prog_load(enum bpf_prog_type type,
+              const struct bpf_insn *insns, int insn_cnt,
+              const char *license)
+{
+    union bpf_attr attr = {
+        .prog_type = type,
+        .insns     = ptr_to_u64(insns),
+        .insn_cnt  = insn_cnt,
+        .license   = ptr_to_u64(license),
+        .log_buf   = ptr_to_u64(bpf_log_buf),
+        .log_size  = LOG_BUF_SIZE,
+        .log_level = 1,
+    };
+\&
+    return bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+}
+.EE
+.in
+.P
+.I prog_type
+is one of the available program types:
+.IP
+.in +4n
+.EX
+enum bpf_prog_type {
+    BPF_PROG_TYPE_UNSPEC,        /* Reserve 0 as invalid
+                                    program type */
+    BPF_PROG_TYPE_SOCKET_FILTER,
+    BPF_PROG_TYPE_KPROBE,
+    BPF_PROG_TYPE_SCHED_CLS,
+    BPF_PROG_TYPE_SCHED_ACT,
+    BPF_PROG_TYPE_TRACEPOINT,
+    BPF_PROG_TYPE_XDP,
+    BPF_PROG_TYPE_PERF_EVENT,
+    BPF_PROG_TYPE_CGROUP_SKB,
+    BPF_PROG_TYPE_CGROUP_SOCK,
+    BPF_PROG_TYPE_LWT_IN,
+    BPF_PROG_TYPE_LWT_OUT,
+    BPF_PROG_TYPE_LWT_XMIT,
+    BPF_PROG_TYPE_SOCK_OPS,
+    BPF_PROG_TYPE_SK_SKB,
+    BPF_PROG_TYPE_CGROUP_DEVICE,
+    BPF_PROG_TYPE_SK_MSG,
+    BPF_PROG_TYPE_RAW_TRACEPOINT,
+    BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+    BPF_PROG_TYPE_LWT_SEG6LOCAL,
+    BPF_PROG_TYPE_LIRC_MODE2,
+    BPF_PROG_TYPE_SK_REUSEPORT,
+    BPF_PROG_TYPE_FLOW_DISSECTOR,
+    /* See /usr/include/linux/bpf.h for the full list. */
+};
+.EE
+.in
+.P
+For further details of eBPF program types, see below.
+.P
+The remaining fields of
+.I bpf_attr
+are set as follows:
+.IP \[bu] 3
+.I insns
+is an array of
+.I "struct bpf_insn"
+instructions.
+.IP \[bu]
+.I insn_cnt
+is the number of instructions in the program referred to by
+.IR insns .
+.IP \[bu]
+.I license
+is a license string, which must be GPL compatible to call helper functions
+marked
+.IR gpl_only .
+(The licensing rules are the same as for kernel modules,
+so that also dual licenses, such as "Dual BSD/GPL", may be used.)
+.IP \[bu]
+.I log_buf
+is a pointer to a caller-allocated buffer in which the in-kernel
+verifier can store the verification log.
+This log is a multi-line string that can be checked by
+the program author in order to understand how the verifier came to
+the conclusion that the eBPF program is unsafe.
+The format of the output can change at any time as the verifier evolves.
+.IP \[bu]
+.I log_size
+size of the buffer pointed to by
+.IR log_buf .
+If the size of the buffer is not large enough to store all
+verifier messages, \-1 is returned and
+.I errno
+is set to
+.BR ENOSPC .
+.IP \[bu]
+.I log_level
+verbosity level of the verifier.
+A value of zero means that the verifier will not provide a log;
+in this case,
+.I log_buf
+must be a null pointer, and
+.I log_size
+must be zero.
+.P
+Applying
+.BR close (2)
+to the file descriptor returned by
+.B BPF_PROG_LOAD
+will unload the eBPF program (but see NOTES).
+.P
+Maps are accessible from eBPF programs and are used to exchange data between
+eBPF programs and between eBPF programs and user-space programs.
+For example,
+eBPF programs can process various events (like kprobe, packets) and
+store their data into a map,
+and user-space programs can then fetch data from the map.
+Conversely, user-space programs can use a map as a configuration mechanism,
+populating the map with values checked by the eBPF program,
+which then modifies its behavior on the fly according to those values.
+.\"
+.\"
+.SS eBPF program types
+The eBPF program type
+.RI ( prog_type )
+determines the subset of kernel helper functions that the program
+may call.
+The program type also determines the program input (context)\[em]the
+format of
+.I "struct bpf_context"
+(which is the data blob passed into the eBPF program as the first argument).
+.\"
+.\" FIXME
+.\" Somewhere in this page we need a general introduction to the
+.\" bpf_context. For example, how does a BPF program access the
+.\" context?
+.P
+For example, a tracing program does not have the exact same
+subset of helper functions as a socket filter program
+(though they may have some helpers in common).
+Similarly,
+the input (context) for a tracing program is a set of register values,
+while for a socket filter it is a network packet.
+.P
+The set of functions available to eBPF programs of a given type may increase
+in the future.
+.P
+The following program types are supported:
+.TP
+.BR BPF_PROG_TYPE_SOCKET_FILTER " (since Linux 3.19)"
+Currently, the set of functions for
+.B BPF_PROG_TYPE_SOCKET_FILTER
+is:
+.IP
+.in +4n
+.EX
+bpf_map_lookup_elem(map_fd, void *key)
+                    /* look up key in a map_fd */
+bpf_map_update_elem(map_fd, void *key, void *value)
+                    /* update key/value */
+bpf_map_delete_elem(map_fd, void *key)
+                    /* delete key in a map_fd */
+.EE
+.in
+.IP
+The
+.I bpf_context
+argument is a pointer to a
+.IR "struct __sk_buff" .
+.\" FIXME: We need some text here to explain how the program
+.\" accesses __sk_buff.
+.\" See 'struct __sk_buff' and commit 9bac3d6d548e5
+.\"
+.\" Alexei commented:
+.\" Actually now in case of SOCKET_FILTER, SCHED_CLS, SCHED_ACT
+.\" the program can now access skb fields.
+.\"
+.TP
+.BR BPF_PROG_TYPE_KPROBE " (since Linux 4.1)"
+.\" commit 2541517c32be2531e0da59dfd7efc1ce844644f5
+[To be documented]
+.\" FIXME Document this program type
+.\"	  Describe allowed helper functions for this program type
+.\"	  Describe bpf_context for this program type
+.\"
+.\" FIXME We need text here to describe 'kern_version'
+.TP
+.BR BPF_PROG_TYPE_SCHED_CLS " (since Linux 4.1)"
+.\" commit 96be4325f443dbbfeb37d2a157675ac0736531a1
+.\" commit e2e9b6541dd4b31848079da80fe2253daaafb549
+[To be documented]
+.\" FIXME Document this program type
+.\"	  Describe allowed helper functions for this program type
+.\"	  Describe bpf_context for this program type
+.TP
+.BR BPF_PROG_TYPE_SCHED_ACT " (since Linux 4.1)"
+.\" commit 94caee8c312d96522bcdae88791aaa9ebcd5f22c
+.\" commit a8cb5f556b567974d75ea29c15181c445c541b1f
+[To be documented]
+.\" FIXME Document this program type
+.\"	  Describe allowed helper functions for this program type
+.\"	  Describe bpf_context for this program type
+.SS Events
+Once a program is loaded, it can be attached to an event.
+Various kernel subsystems have different ways to do so.
+.P
+Since Linux 3.19,
+.\" commit 89aa075832b0da4402acebd698d0411dcc82d03e
+the following call will attach the program
+.I prog_fd
+to the socket
+.IR sockfd ,
+which was created by an earlier call to
+.BR socket (2):
+.P
+.in +4n
+.EX
+setsockopt(sockfd, SOL_SOCKET, SO_ATTACH_BPF,
+           &prog_fd, sizeof(prog_fd));
+.EE
+.in
+.P
+Since Linux 4.1,
+.\" commit 2541517c32be2531e0da59dfd7efc1ce844644f5
+the following call may be used to attach
+the eBPF program referred to by the file descriptor
+.I prog_fd
+to a perf event file descriptor,
+.IR event_fd ,
+that was created by a previous call to
+.BR perf_event_open (2):
+.P
+.in +4n
+.EX
+ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
+.EE
+.in
+.\"
+.\"
+.SH RETURN VALUE
+For a successful call, the return value depends on the operation:
+.TP
+.B BPF_MAP_CREATE
+The new file descriptor associated with the eBPF map.
+.TP
+.B BPF_PROG_LOAD
+The new file descriptor associated with the eBPF program.
+.TP
+All other commands
+Zero.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B E2BIG
+The eBPF program is too large or a map reached the
+.I max_entries
+limit (maximum number of elements).
+.TP
+.B EACCES
+For
+.BR BPF_PROG_LOAD ,
+even though all program instructions are valid, the program has been
+rejected because it was deemed unsafe.
+This may be because it may have
+accessed a disallowed memory region or an uninitialized stack/register or
+because the function constraints don't match the actual types or because
+there was a misaligned memory access.
+In this case, it is recommended to call
+.BR bpf ()
+again with
+.I log_level = 1
+and examine
+.I log_buf
+for the specific reason provided by the verifier.
+.TP
+.B EAGAIN
+For
+.BR BPF_PROG_LOAD ,
+indicates that needed resources are blocked.
+This happens when the verifier detects pending signals
+while it is checking the validity of the bpf program.
+In this case, just call
+.BR bpf ()
+again with the same parameters.
+.TP
+.B EBADF
+.I fd
+is not an open file descriptor.
+.TP
+.B EFAULT
+One of the pointers
+.RI ( key
+or
+.I value
+or
+.I log_buf
+or
+.IR insns )
+is outside the accessible address space.
+.TP
+.B EINVAL
+The value specified in
+.I cmd
+is not recognized by this kernel.
+.TP
+.B EINVAL
+For
+.BR BPF_MAP_CREATE ,
+either
+.I map_type
+or attributes are invalid.
+.TP
+.B EINVAL
+For
+.B BPF_MAP_*_ELEM
+commands,
+some of the fields of
+.I "union bpf_attr"
+that are not used by this command
+are not set to zero.
+.TP
+.B EINVAL
+For
+.BR BPF_PROG_LOAD ,
+indicates an attempt to load an invalid program.
+eBPF programs can be deemed
+invalid due to unrecognized instructions, the use of reserved fields, jumps
+out of range, infinite loops or calls of unknown functions.
+.TP
+.B ENOENT
+For
+.B BPF_MAP_LOOKUP_ELEM
+or
+.BR BPF_MAP_DELETE_ELEM ,
+indicates that the element with the given
+.I key
+was not found.
+.TP
+.B ENOMEM
+Cannot allocate sufficient memory.
+.TP
+.B EPERM
+The call was made without sufficient privilege
+(without the
+.B CAP_SYS_ADMIN
+capability).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.18.
+.SH NOTES
+Prior to Linux 4.4, all
+.BR bpf ()
+commands require the caller to have the
+.B CAP_SYS_ADMIN
+capability.
+From Linux 4.4 onwards,
+.\" commit 1be7f75d1668d6296b80bf35dcf6762393530afc
+an unprivileged user may create limited programs of type
+.B BPF_PROG_TYPE_SOCKET_FILTER
+and associated maps.
+However they may not store kernel pointers within
+the maps and are presently limited to the following helper functions:
+.\" [Linux 5.6] mtk: The list of available functions is, I think, governed
+.\" by the check in net/core/filter.c::bpf_base_func_proto().
+.IP \[bu] 3
+get_random
+.PD 0
+.IP \[bu]
+get_smp_processor_id
+.IP \[bu]
+tail_call
+.IP \[bu]
+ktime_get_ns
+.PD
+.P
+Unprivileged access may be blocked by writing the value 1 to the file
+.IR /proc/sys/kernel/unprivileged_bpf_disabled .
+.P
+eBPF objects (maps and programs) can be shared between processes.
+For example, after
+.BR fork (2),
+the child inherits file descriptors referring to the same eBPF objects.
+In addition, file descriptors referring to eBPF objects can be
+transferred over UNIX domain sockets.
+File descriptors referring to eBPF objects can be duplicated
+in the usual way, using
+.BR dup (2)
+and similar calls.
+An eBPF object is deallocated only after all file descriptors
+referring to the object have been closed.
+.P
+eBPF programs can be written in a restricted C that is compiled (using the
+.B clang
+compiler) into eBPF bytecode.
+Various features are omitted from this restricted C, such as loops,
+global variables, variadic functions, floating-point numbers,
+and passing structures as function arguments.
+Some examples can be found in the
+.I samples/bpf/*_kern.c
+files in the kernel source tree.
+.\" There are also examples for the tc classifier, in the iproute2
+.\" project, in examples/bpf
+.P
+The kernel contains a just-in-time (JIT) compiler that translates
+eBPF bytecode into native machine code for better performance.
+Before Linux 4.15,
+the JIT compiler is disabled by default,
+but its operation can be controlled by writing one of the
+following integer strings to the file
+.IR /proc/sys/net/core/bpf_jit_enable :
+.TP
+.B 0
+Disable JIT compilation (default).
+.TP
+.B 1
+Normal compilation.
+.TP
+.B 2
+Debugging mode.
+The generated opcodes are dumped in hexadecimal into the kernel log.
+These opcodes can then be disassembled using the program
+.I tools/net/bpf_jit_disasm.c
+provided in the kernel source tree.
+.P
+Since Linux 4.15,
+.\" commit 290af86629b25ffd1ed6232c4e9107da031705cb
+the kernel may be configured with the
+.B CONFIG_BPF_JIT_ALWAYS_ON
+option.
+In this case, the JIT compiler is always enabled, and the
+.I bpf_jit_enable
+is initialized to 1 and is immutable.
+(This kernel configuration option was provided as a mitigation for
+one of the Spectre attacks against the BPF interpreter.)
+.P
+The JIT compiler for eBPF is currently
+.\" Last reviewed in Linux 4.18-rc by grepping for BPF_ALU64 in arch/
+.\" and by checking the documentation for bpf_jit_enable in
+.\" Documentation/sysctl/net.txt
+available for the following architectures:
+.IP \[bu] 3
+x86-64 (since Linux 3.18; cBPF since Linux 3.0);
+.\" commit 0a14842f5a3c0e88a1e59fac5c3025db39721f74
+.PD 0
+.IP \[bu]
+ARM32 (since Linux 3.18; cBPF since Linux 3.4);
+.\" commit ddecdfcea0ae891f782ae853771c867ab51024c2
+.IP \[bu]
+SPARC 32 (since Linux 3.18; cBPF since Linux 3.5);
+.\" commit 2809a2087cc44b55e4377d7b9be3f7f5d2569091
+.IP \[bu]
+ARM-64 (since Linux 3.18);
+.\" commit e54bcde3d69d40023ae77727213d14f920eb264a
+.IP \[bu]
+s390 (since Linux 4.1; cBPF since Linux 3.7);
+.\" commit c10302efe569bfd646b4c22df29577a4595b4580
+.IP \[bu]
+PowerPC 64 (since Linux 4.8; cBPF since Linux 3.1);
+.\" commit 0ca87f05ba8bdc6791c14878464efc901ad71e99
+.\" commit 156d0e290e969caba25f1851c52417c14d141b24
+.IP \[bu]
+SPARC 64 (since Linux 4.12);
+.\" commit 7a12b5031c6b947cc13918237ae652b536243b76
+.IP \[bu]
+x86-32 (since Linux 4.18);
+.\" commit 03f5781be2c7b7e728d724ac70ba10799cc710d7
+.IP \[bu]
+MIPS 64 (since Linux 4.18; cBPF since Linux 3.16);
+.\" commit c6610de353da5ca6eee5b8960e838a87a90ead0c
+.\" commit f381bf6d82f032b7410185b35d000ea370ac706b
+.IP \[bu]
+riscv (since Linux 5.1).
+.\" commit 2353ecc6f91fd15b893fa01bf85a1c7a823ee4f2
+.PD
+.SH EXAMPLES
+.\" SRC BEGIN (bpf.c)
+.EX
+/* bpf+sockets example:
+ * 1. create array map of 256 elements
+ * 2. load program that counts number of packets received
+ *    r0 = skb\->data[ETH_HLEN + offsetof(struct iphdr, protocol)]
+ *    map[r0]++
+ * 3. attach prog_fd to raw socket via setsockopt()
+ * 4. print number of received TCP/UDP packets every second
+ */
+int
+main(int argc, char *argv[])
+{
+    int sock, map_fd, prog_fd, key;
+    long long value = 0, tcp_cnt, udp_cnt;
+\&
+    map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(key),
+                            sizeof(value), 256);
+    if (map_fd < 0) {
+        printf("failed to create map \[aq]%s\[aq]\en", strerror(errno));
+        /* likely not run as root */
+        return 1;
+    }
+\&
+    struct bpf_insn prog[] = {
+        BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),        /* r6 = r1 */
+        BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol)),
+                                /* r0 = ip\->proto */
+        BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, \-4),
+                                /* *(u32 *)(fp \- 4) = r0 */
+        BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),       /* r2 = fp */
+        BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, \-4),      /* r2 = r2 \- 4 */
+        BPF_LD_MAP_FD(BPF_REG_1, map_fd),           /* r1 = map_fd */
+        BPF_CALL_FUNC(BPF_FUNC_map_lookup_elem),
+                                /* r0 = map_lookup(r1, r2) */
+        BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+                                /* if (r0 == 0) goto pc+2 */
+        BPF_MOV64_IMM(BPF_REG_1, 1),                /* r1 = 1 */
+        BPF_XADD(BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0),
+                                /* lock *(u64 *) r0 += r1 */
+.\"                                == atomic64_add
+        BPF_MOV64_IMM(BPF_REG_0, 0),                /* r0 = 0 */
+        BPF_EXIT_INSN(),                            /* return r0 */
+    };
+\&
+    prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, prog,
+                            sizeof(prog) / sizeof(prog[0]), "GPL");
+\&
+    sock = open_raw_sock("lo");
+\&
+    assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd,
+                      sizeof(prog_fd)) == 0);
+\&
+    for (;;) {
+        key = IPPROTO_TCP;
+        assert(bpf_lookup_elem(map_fd, &key, &tcp_cnt) == 0);
+        key = IPPROTO_UDP;
+        assert(bpf_lookup_elem(map_fd, &key, &udp_cnt) == 0);
+        printf("TCP %lld UDP %lld packets\en", tcp_cnt, udp_cnt);
+        sleep(1);
+    }
+\&
+    return 0;
+}
+.EE
+.\" SRC END
+.P
+Some complete working code can be found in the
+.I samples/bpf
+directory in the kernel source tree.
+.SH SEE ALSO
+.BR seccomp (2),
+.BR bpf\-helpers (7),
+.BR socket (7),
+.BR tc (8),
+.BR tc\-bpf (8)
+.P
+Both classic and extended BPF are explained in the kernel source file
+.IR Documentation/networking/filter.txt .
diff --git a/man/man2/break.2 b/man/man2/break.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/break.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/brk.2 b/man/man2/brk.2
new file mode 100644
index 000000000..40ba0f302
--- /dev/null
+++ b/man/man2/brk.2
@@ -0,0 +1,153 @@
+.\" Copyright (c) 1993 Michael Haardt, (michael@moria.de)
+.\" and Copyright 2006, 2008, Michael Kerrisk <tmk.manpages@gmail.com>
+.\" Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Wed Jul 21 19:52:58 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Aug 21 17:40:38 1994 by Rik Faith <faith@cs.unc.edu>
+.\"
+.TH brk 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+brk, sbrk \- change data segment size
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int brk(void *" addr );
+.BI "void *sbrk(intptr_t " increment );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR brk (),
+.BR sbrk ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+            || ((_XOPEN_SOURCE >= 500) &&
+                ! (_POSIX_C_SOURCE >= 200112L))
+.\"    (_XOPEN_SOURCE >= 500 ||
+.\"        _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
+    From glibc 2.12 to glibc 2.19:
+        _BSD_SOURCE || _SVID_SOURCE
+            || ((_XOPEN_SOURCE >= 500) &&
+                ! (_POSIX_C_SOURCE >= 200112L))
+.\"    (_XOPEN_SOURCE >= 500 ||
+.\"        _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
+    Before glibc 2.12:
+        _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+.BR brk ()
+and
+.BR sbrk ()
+change the location of the
+.IR "program break" ,
+which defines the end of the process's data segment
+(i.e., the program break is the first location after the end of the
+uninitialized data segment).
+Increasing the program break has the effect of
+allocating memory to the process;
+decreasing the break deallocates memory.
+.P
+.BR brk ()
+sets the end of the data segment to the value specified by
+.IR addr ,
+when that value is reasonable, the system has enough memory,
+and the process does not exceed its maximum data size (see
+.BR setrlimit (2)).
+.P
+.BR sbrk ()
+increments the program's data space by
+.I increment
+bytes.
+Calling
+.BR sbrk ()
+with an
+.I increment
+of 0 can be used to find the current location of the program break.
+.SH RETURN VALUE
+On success,
+.BR brk ()
+returns zero.
+On error, \-1 is returned, and
+.I errno
+is set to
+.BR ENOMEM .
+.P
+On success,
+.BR sbrk ()
+returns the previous program break.
+(If the break was increased,
+then this value is a pointer to the start of the newly allocated memory).
+On error,
+.I "(void\ *)\ \-1"
+is returned, and
+.I errno
+is set to
+.BR ENOMEM .
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD; SUSv1, marked LEGACY in SUSv2, removed in POSIX.1-2001.
+.\"
+.\" .BR brk ()
+.\" and
+.\" .BR sbrk ()
+.\" are not defined in the C Standard and are deliberately excluded from the
+.\" POSIX.1-1990 standard (see paragraphs B.1.1.1.3 and B.8.3.3).
+.SH NOTES
+Avoid using
+.BR brk ()
+and
+.BR sbrk ():
+the
+.BR malloc (3)
+memory allocation package is the
+portable and comfortable way of allocating memory.
+.P
+Various systems use various types for the argument of
+.BR sbrk ().
+Common are \fIint\fP, \fIssize_t\fP, \fIptrdiff_t\fP, \fIintptr_t\fP.
+.\" One sees
+.\" \fIint\fP (e.g., XPGv4, DU 4.0, HP-UX 11, FreeBSD 4.0, OpenBSD 3.2),
+.\" \fIssize_t\fP (OSF1 2.0, Irix 5.3, 6.5),
+.\" \fIptrdiff_t\fP (libc4, libc5, ulibc, glibc 2.0, 2.1),
+.\" \fIintptr_t\fP (e.g., XPGv5, AIX, SunOS 5.8, 5.9, FreeBSD 4.7, NetBSD 1.6,
+.\" Tru64 5.1, glibc2.2).
+.SS C library/kernel differences
+The return value described above for
+.BR brk ()
+is the behavior provided by the glibc wrapper function for the Linux
+.BR brk ()
+system call.
+(On most other implementations, the return value from
+.BR brk ()
+is the same; this return value was also specified in SUSv2.)
+However,
+the actual Linux system call returns the new program break on success.
+On failure, the system call returns the current break.
+The glibc wrapper function does some work
+(i.e., checks whether the new break is less than
+.IR addr )
+to provide the 0 and \-1 return values described above.
+.P
+On Linux,
+.BR sbrk ()
+is implemented as a library function that uses the
+.BR brk ()
+system call, and does some internal bookkeeping so that it can
+return the old break value.
+.SH SEE ALSO
+.BR execve (2),
+.BR getrlimit (2),
+.BR end (3),
+.BR malloc (3)
diff --git a/man/man2/cacheflush.2 b/man/man2/cacheflush.2
new file mode 100644
index 000000000..bc38355e6
--- /dev/null
+++ b/man/man2/cacheflush.2
@@ -0,0 +1,143 @@
+.\" Written by Ralf Baechle (ralf@waldorf-gmbh.de),
+.\" Copyright (c) 1994, 1995 Waldorf GMBH
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH cacheflush 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cacheflush \- flush contents of instruction and/or data cache
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/cachectl.h>
+.P
+.BI "int cacheflush(void " addr [. nbytes "], int "nbytes ", int "cache );
+.fi
+.P
+.IR Note :
+On some architectures,
+there is no glibc wrapper for this system call; see NOTES.
+.SH DESCRIPTION
+.BR cacheflush ()
+flushes the contents of the indicated cache(s) for the
+user addresses in the range
+.I addr
+to
+.IR (addr+nbytes\-1) .
+.I cache
+may be one of:
+.TP
+.B ICACHE
+Flush the instruction cache.
+.TP
+.B DCACHE
+Write back to memory and invalidate the affected valid cache lines.
+.TP
+.B BCACHE
+Same as
+.BR (ICACHE|DCACHE) .
+.SH RETURN VALUE
+.BR cacheflush ()
+returns 0 on success.
+On error, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Some or all of the address range
+.I addr
+to
+.I (addr+nbytes\-1)
+is not accessible.
+.TP
+.B EINVAL
+.I cache
+is not one of
+.BR ICACHE ,
+.BR DCACHE ,
+or
+.B BCACHE
+(but see BUGS).
+.SH VERSIONS
+.BR cacheflush ()
+should not be used in programs intended to be portable.
+On Linux, this call first appeared on the MIPS architecture,
+but nowadays, Linux provides a
+.BR cacheflush ()
+system call on some other architectures, but with different arguments.
+.SS Architecture-specific variants
+glibc provides a wrapper for this system call,
+with the prototype shown in SYNOPSIS,
+for the following architectures:
+ARC, CSKY, MIPS, and NIOS2.
+.P
+On some other architectures,
+Linux provides this system call, with different arguments:
+.TP
+M68K:
+.nf
+.BI "int cacheflush(unsigned long " addr ", int " scope ", int " cache ,
+.BI "               unsigned long " len );
+.fi
+.TP
+SH:
+.nf
+.BI "int cacheflush(unsigned long " addr ", unsigned long " len ", int " op );
+.fi
+.TP
+NDS32:
+.nf
+.BI "int cacheflush(unsigned int " start ", unsigned int " end ", int " cache );
+.fi
+.P
+On the above architectures,
+glibc does not provide a wrapper for this system call; call it using
+.BR syscall (2).
+.SS GCC alternative
+Unless you need the finer grained control that this system call provides,
+you probably want to use the GCC built-in function
+.BR __builtin___clear_cache (),
+which provides a portable interface
+across platforms supported by GCC and compatible compilers:
+.P
+.in +4n
+.EX
+.BI "void __builtin___clear_cache(void *" begin ", void *" end );
+.EE
+.in
+.P
+On platforms that don't require instruction cache flushes,
+.BR __builtin___clear_cache ()
+has no effect.
+.P
+.IR Note :
+On some GCC-compatible compilers,
+the prototype for this built-in function uses
+.I char *
+instead of
+.I void *
+for the parameters.
+.SH STANDARDS
+Historically, this system call was available on all MIPS UNIX variants
+including RISC/os, IRIX, Ultrix, NetBSD, OpenBSD, and FreeBSD
+(and also on some non-UNIX MIPS operating systems), so that
+the existence of this call in MIPS operating systems is a de-facto
+standard.
+.SH BUGS
+Linux kernels older than Linux 2.6.11 ignore the
+.I addr
+and
+.I nbytes
+arguments, making this function fairly expensive.
+Therefore, the whole cache is always flushed.
+.P
+This function always behaves as if
+.B BCACHE
+has been passed for the
+.I cache
+argument and does not do any error checking on the
+.I cache
+argument.
diff --git a/man/man2/capget.2 b/man/man2/capget.2
new file mode 100644
index 000000000..feaa36d1d
--- /dev/null
+++ b/man/man2/capget.2
@@ -0,0 +1,260 @@
+.\" Copyright: written by Andrew Morgan <morgan@kernel.org>
+.\" and Copyright 2006, 2008, Michael Kerrisk <tmk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Modified by David A. Wheeler <dwheeler@ida.org>
+.\" Modified 2004-05-27, mtk
+.\" Modified 2004-06-21, aeb
+.\" Modified 2008-04-28, morgan of kernel.org
+.\"     Update in line with addition of file capabilities and
+.\"     64-bit capability sets in Linux 2.6.2[45].
+.\" Modified 2009-01-26, andi kleen
+.\"
+.TH capget 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+capget, capset \- set/get capabilities of thread(s)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/capability.h>" " /* Definition of " CAP_* " and"
+.BR "                                 _LINUX_CAPABILITY_*" " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_capget, cap_user_header_t " hdrp ,
+.BI "            cap_user_data_t " datap );
+.BI "int syscall(SYS_capset, cap_user_header_t " hdrp ,
+.BI "            const cap_user_data_t " datap );
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+These two system calls are the raw kernel interface for getting and
+setting thread capabilities.
+Not only are these system calls specific to Linux,
+but the kernel API is likely to change and use of
+these system calls (in particular the format of the
+.I cap_user_*_t
+types) is subject to extension with each kernel revision,
+but old programs will keep working.
+.P
+The portable interfaces are
+.BR cap_set_proc (3)
+and
+.BR cap_get_proc (3);
+if possible, you should use those interfaces in applications; see NOTES.
+.\"
+.SS Current details
+Now that you have been warned, some current kernel details.
+The structures are defined as follows.
+.P
+.in +4n
+.EX
+#define _LINUX_CAPABILITY_VERSION_1  0x19980330
+#define _LINUX_CAPABILITY_U32S_1     1
+\&
+        /* V2 added in Linux 2.6.25; deprecated */
+#define _LINUX_CAPABILITY_VERSION_2  0x20071026
+.\" commit e338d263a76af78fe8f38a72131188b58fceb591
+.\" Added 64 bit capability support
+#define _LINUX_CAPABILITY_U32S_2     2
+\&
+        /* V3 added in Linux 2.6.26 */
+#define _LINUX_CAPABILITY_VERSION_3  0x20080522
+.\" commit ca05a99a54db1db5bca72eccb5866d2a86f8517f
+#define _LINUX_CAPABILITY_U32S_3     2
+\&
+typedef struct __user_cap_header_struct {
+   __u32 version;
+   int pid;
+} *cap_user_header_t;
+\&
+typedef struct __user_cap_data_struct {
+   __u32 effective;
+   __u32 permitted;
+   __u32 inheritable;
+} *cap_user_data_t;
+.EE
+.in
+.P
+The
+.IR effective ,
+.IR permitted ,
+and
+.I inheritable
+fields are bit masks of the capabilities defined in
+.BR capabilities (7).
+Note that the
+.B CAP_*
+values are bit indexes and need to be bit-shifted before ORing into
+the bit fields.
+To define the structures for passing to the system call, you have to use the
+.I struct __user_cap_header_struct
+and
+.I struct __user_cap_data_struct
+names because the typedefs are only pointers.
+.P
+Kernels prior to Linux 2.6.25 prefer
+32-bit capabilities with version
+.BR _LINUX_CAPABILITY_VERSION_1 .
+Linux 2.6.25 added 64-bit capability sets, with version
+.BR _LINUX_CAPABILITY_VERSION_2 .
+There was, however, an API glitch, and Linux 2.6.26 added
+.B _LINUX_CAPABILITY_VERSION_3
+to fix the problem.
+.P
+Note that 64-bit capabilities use
+.I datap[0]
+and
+.IR datap[1] ,
+whereas 32-bit capabilities use only
+.IR datap[0] .
+.P
+On kernels that support file capabilities (VFS capabilities support),
+these system calls behave slightly differently.
+This support was added as an option in Linux 2.6.24,
+and became fixed (nonoptional) in Linux 2.6.33.
+.P
+For
+.BR capget ()
+calls, one can probe the capabilities of any process by specifying its
+process ID with the
+.I hdrp\->pid
+field value.
+.P
+For details on the data, see
+.BR capabilities (7).
+.\"
+.SS With VFS capabilities support
+VFS capabilities employ a file extended attribute (see
+.BR xattr (7))
+to allow capabilities to be attached to executables.
+This privilege model obsoletes kernel support for one process
+asynchronously setting the capabilities of another.
+That is, on kernels that have VFS capabilities support, when calling
+.BR capset (),
+the only permitted values for
+.I hdrp\->pid
+are 0 or, equivalently, the value returned by
+.BR gettid (2).
+.\"
+.SS Without VFS capabilities support
+On older kernels that do not provide VFS capabilities support
+.BR capset ()
+can, if the caller has the
+.B CAP_SETPCAP
+capability, be used to change not only the caller's own capabilities,
+but also the capabilities of other threads.
+The call operates on the capabilities of the thread specified by the
+.I pid
+field of
+.I hdrp
+when that is nonzero, or on the capabilities of the calling thread if
+.I pid
+is 0.
+If
+.I pid
+refers to a single-threaded process, then
+.I pid
+can be specified as a traditional process ID;
+operating on a thread of a multithreaded process requires a thread ID
+of the type returned by
+.BR gettid (2).
+For
+.BR capset (),
+.I pid
+can also be: \-1, meaning perform the change on all threads except the
+caller and
+.BR init (1);
+or a value less than \-1, in which case the change is applied
+to all members of the process group whose ID is \-\fIpid\fP.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+The calls fail with the error
+.BR EINVAL ,
+and set the
+.I version
+field of
+.I hdrp
+to the kernel preferred value of
+.B _LINUX_CAPABILITY_VERSION_?
+when an unsupported
+.I version
+value is specified.
+In this way, one can probe what the current
+preferred capability revision is.
+.SH ERRORS
+.TP
+.B EFAULT
+Bad memory address.
+.I hdrp
+must not be NULL.
+.I datap
+may be NULL only when the user is trying to determine the preferred
+capability version format supported by the kernel.
+.TP
+.B EINVAL
+One of the arguments was invalid.
+.TP
+.B EPERM
+An attempt was made to add a capability to the permitted set, or to set
+a capability in the effective set that is not in the
+permitted set.
+.TP
+.B EPERM
+An attempt was made to add a capability to the inheritable set, and either:
+.RS
+.IP \[bu] 3
+that capability was not in the caller's bounding set; or
+.IP \[bu]
+the capability was not in the caller's permitted set
+and the caller lacked the
+.B CAP_SETPCAP
+capability in its effective set.
+.RE
+.TP
+.B EPERM
+The caller attempted to use
+.BR capset ()
+to modify the capabilities of a thread other than itself,
+but lacked sufficient privilege.
+For kernels supporting VFS
+capabilities, this is never permitted.
+For kernels lacking VFS
+support, the
+.B CAP_SETPCAP
+capability is required.
+(A bug in kernels before Linux 2.6.11 meant that this error could also
+occur if a thread without this capability tried to change its
+own capabilities by specifying the
+.I pid
+field as a nonzero value (i.e., the value returned by
+.BR getpid (2))
+instead of 0.)
+.TP
+.B ESRCH
+No such thread.
+.SH STANDARDS
+Linux.
+.SH NOTES
+The portable interface to the capability querying and setting
+functions is provided by the
+.I libcap
+library and is available here:
+.br
+.UR http://git.kernel.org/cgit\:/linux\:/kernel\:/git\:/morgan\:\:/libcap.git
+.UE
+.SH SEE ALSO
+.BR clone (2),
+.BR gettid (2),
+.BR capabilities (7)
diff --git a/man/man2/capset.2 b/man/man2/capset.2
new file mode 100644
index 000000000..9e829cbd8
--- /dev/null
+++ b/man/man2/capset.2
@@ -0,0 +1 @@
+.so man2/capget.2
diff --git a/man/man2/chdir.2 b/man/man2/chdir.2
new file mode 100644
index 000000000..d33efbdfe
--- /dev/null
+++ b/man/man2/chdir.2
@@ -0,0 +1,127 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-04-15 by Michael Chastain <mec@shell.portal.com>:
+.\"   Added 'fchdir'. Fixed bugs in error section.
+.\" Modified 1996-10-21 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1997-08-21 by Joseph S. Myers <jsm28@cam.ac.uk>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH chdir 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+chdir, fchdir \- change working directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int chdir(const char *" path );
+.BI "int fchdir(int " fd );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fchdir ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc up to and including 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR chdir ()
+changes the current working directory of the calling process to the
+directory specified in
+.IR path .
+.P
+.BR fchdir ()
+is identical to
+.BR chdir ();
+the only difference is that the directory is given as an
+open file descriptor.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Depending on the filesystem, other errors can be returned.
+The more
+general errors for
+.BR chdir ()
+are listed below:
+.TP
+.B EACCES
+Search permission is denied for one of the components of
+.IR path .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EFAULT
+.I path
+points outside your accessible address space.
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR path .
+.TP
+.B ENAMETOOLONG
+.I path
+is too long.
+.TP
+.B ENOENT
+The directory specified in
+.I path
+does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of
+.I path
+is not a directory.
+.P
+The general errors for
+.BR fchdir ()
+are listed below:
+.TP
+.B EACCES
+Search permission was denied on the directory open on
+.IR fd .
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B ENOTDIR
+.I fd
+does not refer to a directory.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD.
+.SH NOTES
+The current working directory is the starting point for interpreting
+relative pathnames (those not starting with \[aq]/\[aq]).
+.P
+A child process created via
+.BR fork (2)
+inherits its parent's current working directory.
+The current working directory is left unchanged by
+.BR execve (2).
+.SH SEE ALSO
+.BR chroot (2),
+.BR getcwd (3),
+.BR path_resolution (7)
diff --git a/man/man2/chmod.2 b/man/man2/chmod.2
new file mode 100644
index 000000000..255f76b1c
--- /dev/null
+++ b/man/man2/chmod.2
@@ -0,0 +1,347 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\" and Copyright (C) 2006, 2014 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1997-01-12 by Michael Haardt
+.\"   <michael@cantor.informatik.rwth-aachen.de>: NFS details
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH chmod 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+chmod, fchmod, fchmodat \- change permissions of a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/stat.h>
+.P
+.BI "int chmod(const char *" pathname ", mode_t " mode );
+.BI "int fchmod(int " fd ", mode_t " mode );
+.P
+.BR "#include <fcntl.h>" "           /* Definition of AT_* constants */"
+.B #include <sys/stat.h>
+.P
+.BI "int fchmodat(int " dirfd ", const char *" pathname ", mode_t " \
+mode ", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.nf
+.BR fchmod ():
+    Since glibc 2.24:
+        _POSIX_C_SOURCE >= 199309L
+.\"        || (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+    glibc 2.19 to glibc 2.23
+        _POSIX_C_SOURCE
+    glibc 2.16 to glibc 2.19:
+        _BSD_SOURCE || _POSIX_C_SOURCE
+    glibc 2.12 to glibc 2.16:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+            || _POSIX_C_SOURCE >= 200809L
+    glibc 2.11 and earlier:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"        || (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+.fi
+.P
+.BR fchmodat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR chmod ()
+and
+.BR fchmod ()
+system calls change a file's mode bits.
+(The file mode consists of the file permission bits plus the set-user-ID,
+set-group-ID, and sticky bits.)
+These system calls differ only in how the file is specified:
+.IP \[bu] 3
+.BR chmod ()
+changes the mode of the file specified whose pathname is given in
+.IR pathname ,
+which is dereferenced if it is a symbolic link.
+.IP \[bu]
+.BR fchmod ()
+changes the mode of the file referred to by the open file descriptor
+.IR fd .
+.P
+The new file mode is specified in
+.IR mode ,
+which is a bit mask created by ORing together zero or
+more of the following:
+.TP 18
+.BR S_ISUID "  (04000)"
+set-user-ID (set process effective user ID on
+.BR execve (2))
+.TP
+.BR S_ISGID "  (02000)"
+set-group-ID (set process effective group ID on
+.BR execve (2);
+mandatory locking, as described in
+.BR fcntl (2);
+take a new file's group from parent directory, as described in
+.BR chown (2)
+and
+.BR mkdir (2))
+.TP
+.BR S_ISVTX "  (01000)"
+sticky bit (restricted deletion flag, as described in
+.BR unlink (2))
+.TP
+.BR S_IRUSR "  (00400)"
+read by owner
+.TP
+.BR S_IWUSR "  (00200)"
+write by owner
+.TP
+.BR S_IXUSR "  (00100)"
+execute/search by owner ("search" applies for directories,
+and means that entries within the directory can be accessed)
+.TP
+.BR S_IRGRP "  (00040)"
+read by group
+.TP
+.BR S_IWGRP "  (00020)"
+write by group
+.TP
+.BR S_IXGRP "  (00010)"
+execute/search by group
+.TP
+.BR S_IROTH "  (00004)"
+read by others
+.TP
+.BR S_IWOTH "  (00002)"
+write by others
+.TP
+.BR S_IXOTH "  (00001)"
+execute/search by others
+.P
+The effective UID of the calling process must match the owner of the file,
+or the process must be privileged (Linux: it must have the
+.B CAP_FOWNER
+capability).
+.P
+If the calling process is not privileged (Linux: does not have the
+.B CAP_FSETID
+capability), and the group of the file does not match
+the effective group ID of the process or one of its
+supplementary group IDs, the
+.B S_ISGID
+bit will be turned off,
+but this will not cause an error to be returned.
+.P
+As a security measure, depending on the filesystem,
+the set-user-ID and set-group-ID execution bits
+may be turned off if a file is written.
+(On Linux, this occurs if the writing process does not have the
+.B CAP_FSETID
+capability.)
+On some filesystems, only the superuser can set the sticky bit,
+which may have a special meaning.
+For the sticky bit, and for set-user-ID and set-group-ID bits on
+directories, see
+.BR inode (7).
+.P
+On NFS filesystems, restricting the permissions will immediately influence
+already open files, because the access control is done on the server, but
+open files are maintained by the client.
+Widening the permissions may be
+delayed for other clients if attribute caching is enabled on them.
+.\"
+.\"
+.SS fchmodat()
+The
+.BR fchmodat ()
+system call operates in exactly the same way as
+.BR chmod (),
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR chmod ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR chmod ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+.I flags
+can either be 0, or include the following flag:
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+is a symbolic link, do not dereference it:
+instead operate on the link itself.
+This flag is not currently implemented.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR fchmodat ().
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Depending on the filesystem,
+errors other than those listed below can be returned.
+.P
+The more general errors for
+.BR chmod ()
+are listed below:
+.TP
+.B EACCES
+Search permission is denied on a component of the path prefix.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( fchmod ())
+The file descriptor
+.I fd
+is not valid.
+.TP
+.B EBADF
+.RB ( fchmodat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I pathname
+points outside your accessible address space.
+.TP
+.B EINVAL
+.RB ( fchmodat ())
+Invalid flag specified in
+.IR flags .
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+The file does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of the path prefix is not a directory.
+.TP
+.B ENOTDIR
+.RB ( fchmodat ())
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B ENOTSUP
+.RB ( fchmodat ())
+.I flags
+specified
+.BR AT_SYMLINK_NOFOLLOW ,
+which is not supported.
+.TP
+.B EPERM
+The effective UID does not match the owner of the file,
+and the process is not privileged (Linux: it does not have the
+.B CAP_FOWNER
+capability).
+.TP
+.B EPERM
+The file is marked immutable or append-only.
+(See
+.BR ioctl_iflags (2).)
+.TP
+.B EROFS
+The named file resides on a read-only filesystem.
+.SH VERSIONS
+.SS C library/kernel differences
+The GNU C library
+.BR fchmodat ()
+wrapper function implements the POSIX-specified
+interface described in this page.
+This interface differs from the underlying Linux system call, which does
+.I not
+have a
+.I flags
+argument.
+.SS glibc notes
+On older kernels where
+.BR fchmodat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR chmod ().
+When
+.I pathname
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.I /proc/self/fd
+that corresponds to the
+.I dirfd
+argument.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR chmod ()
+.TQ
+.BR fchmod ()
+4.4BSD, SVr4, POSIX.1-2001.
+.TP
+.BR fchmodat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.SH SEE ALSO
+.BR chmod (1),
+.BR chown (2),
+.BR execve (2),
+.BR open (2),
+.BR stat (2),
+.BR inode (7),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/chown.2 b/man/man2/chown.2
new file mode 100644
index 000000000..ffba3acaf
--- /dev/null
+++ b/man/man2/chown.2
@@ -0,0 +1,471 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\" and Copyright (c) 1998 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (c) 2006, 2007, 2008, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-07-09 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 1996-11-06 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1997-05-18 by Michael Haardt <michael@cantor.informatik.rwth-aachen.de>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2007-07-08, mtk, added an example program; updated SYNOPSIS
+.\" 2008-05-08, mtk, Describe rules governing ownership of new files
+.\"     (bsdgroups versus sysvgroups, and the effect of the parent
+.\"     directory's set-group-ID mode bit).
+.\"
+.TH chown 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+chown, fchown, lchown, fchownat \- change ownership of a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int chown(const char *" pathname ", uid_t " owner ", gid_t " group );
+.BI "int fchown(int " fd ", uid_t " owner ", gid_t " group );
+.BI "int lchown(const char *" pathname ", uid_t " owner ", gid_t " group );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of AT_* constants */"
+.B #include <unistd.h>
+.P
+.BI "int fchownat(int " dirfd ", const char *" pathname ,
+.BI "             uid_t " owner ", gid_t " group ", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fchown (),
+.BR lchown ():
+.nf
+    /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.P
+.BR fchownat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+These system calls change the owner and group of a file.
+The
+.BR chown (),
+.BR fchown (),
+and
+.BR lchown ()
+system calls differ only in how the file is specified:
+.IP \[bu] 3
+.BR chown ()
+changes the ownership of the file specified by
+.IR pathname ,
+which is dereferenced if it is a symbolic link.
+.IP \[bu]
+.BR fchown ()
+changes the ownership of the file referred to by the open file descriptor
+.IR fd .
+.IP \[bu]
+.BR lchown ()
+is like
+.BR chown (),
+but does not dereference symbolic links.
+.P
+Only a privileged process (Linux: one with the
+.B CAP_CHOWN
+capability) may change the owner of a file.
+The owner of a file may change the group of the file
+to any group of which that owner is a member.
+A privileged process (Linux: with
+.BR CAP_CHOWN )
+may change the group arbitrarily.
+.P
+If the
+.I owner
+or
+.I group
+is specified as \-1, then that ID is not changed.
+.P
+When the owner or group of an executable file is
+changed by an unprivileged user, the
+.B S_ISUID
+and
+.B S_ISGID
+mode bits are cleared.
+POSIX does not specify whether
+this also should happen when root does the
+.BR chown ();
+the Linux behavior depends on the kernel version,
+and since Linux 2.2.13, root is treated like other users.
+.\" In Linux 2.0 kernels, superuser was like everyone else
+.\" In Linux 2.2, up to Linux 2.2.12, these bits were not cleared for superuser.
+.\" Since Linux 2.2.13, superuser is once more like everyone else.
+In case of a non-group-executable file (i.e., one for which the
+.B S_IXGRP
+bit is not set) the
+.B S_ISGID
+bit indicates mandatory locking, and is not cleared by a
+.BR chown ().
+.P
+When the owner or group of an executable file is changed (by any user),
+all capability sets for the file are cleared.
+.\"
+.SS fchownat()
+The
+.BR fchownat ()
+system call operates in exactly the same way as
+.BR chown (),
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR chown ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR chown ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+The
+.I flags
+argument is a bit mask created by ORing together
+0 or more of the following values;
+.TP
+.BR AT_EMPTY_PATH " (since Linux 2.6.39)"
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.I dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+In this case,
+.I dirfd
+can refer to any type of file, not just a directory.
+If
+.I dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+is a symbolic link, do not dereference it:
+instead operate on the link itself, like
+.BR lchown ().
+(By default,
+.BR fchownat ()
+dereferences symbolic links, like
+.BR chown ().)
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR fchownat ().
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Depending on the filesystem,
+errors other than those listed below can be returned.
+.P
+The more general errors for
+.BR chown ()
+are listed below.
+.TP
+.B EACCES
+Search permission is denied on a component of the path prefix.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( fchown ())
+.I fd
+is not a valid open file descriptor.
+.TP
+.B EBADF
+.RB ( fchownat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I pathname
+points outside your accessible address space.
+.TP
+.B EINVAL
+.RB ( fchownat ())
+Invalid flag specified in
+.IR flags .
+.TP
+.B EIO
+.RB ( fchown ())
+A low-level I/O error occurred while modifying the inode.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+The file does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of the path prefix is not a directory.
+.TP
+.B ENOTDIR
+.RB ( fchownat ())
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EPERM
+The calling process did not have the required permissions
+(see above) to change owner and/or group.
+.TP
+.B EPERM
+The file is marked immutable or append-only.
+(See
+.BR ioctl_iflags (2).)
+.TP
+.B EROFS
+The named file resides on a read-only filesystem.
+.SH VERSIONS
+The 4.4BSD version can be
+used only by the superuser (that is, ordinary users cannot give away files).
+.\" chown():
+.\" SVr4 documents EINVAL, EINTR, ENOLINK and EMULTIHOP returns, but no
+.\" ENOMEM.  POSIX.1 does not document ENOMEM or ELOOP error conditions.
+.\" fchown():
+.\" SVr4 documents additional EINVAL, EIO, EINTR, and ENOLINK
+.\" error conditions.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR chown ()
+.TQ
+.BR fchown ()
+.TQ
+.BR lchown ()
+4.4BSD, SVr4, POSIX.1-2001.
+.TP
+.BR fchownat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.SH NOTES
+.SS Ownership of new files
+When a new file is created (by, for example,
+.BR open (2)
+or
+.BR mkdir (2)),
+its owner is made the same as the filesystem user ID of the
+creating process.
+The group of the file depends on a range of factors,
+including the type of filesystem,
+the options used to mount the filesystem,
+and whether or not the set-group-ID mode bit is enabled
+on the parent directory.
+If the filesystem supports the
+.B "\-o\ grpid"
+(or, synonymously
+.BR "\-o\ bsdgroups" )
+and
+.B "\-o\ nogrpid"
+(or, synonymously
+.BR "\-o\ sysvgroups" )
+.BR mount (8)
+options, then the rules are as follows:
+.IP \[bu] 3
+If the filesystem is mounted with
+.BR "\-o\ grpid" ,
+then the group of a new file is made
+the same as that of the parent directory.
+.IP \[bu]
+If the filesystem is mounted with
+.B \-o\ nogrpid
+and the set-group-ID bit is disabled on the parent directory,
+then the group of a new file is made the same as the
+process's filesystem GID.
+.IP \[bu]
+If the filesystem is mounted with
+.B \-o\ nogrpid
+and the set-group-ID bit is enabled on the parent directory,
+then the group of a new file is made
+the same as that of the parent directory.
+.P
+As at Linux 4.12,
+the
+.B \-o\ grpid
+and
+.B \-o\ nogrpid
+mount options are supported by ext2, ext3, ext4, and XFS.
+Filesystems that don't support these mount options follow the
+.B \-o\ nogrpid
+rules.
+.SS glibc notes
+On older kernels where
+.BR fchownat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR chown ()
+and
+.BR lchown ().
+When
+.I pathname
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.I /proc/self/fd
+that corresponds to the
+.I dirfd
+argument.
+.SS NFS
+The
+.BR chown ()
+semantics are deliberately violated on NFS filesystems
+which have UID mapping enabled.
+Additionally, the semantics of all system
+calls which access the file contents are violated, because
+.BR chown ()
+may cause immediate access revocation on already open files.
+Client side
+caching may lead to a delay between the time where ownership have
+been changed to allow access for a user and the time where the file can
+actually be accessed by the user on other clients.
+.SS Historical details
+The original Linux
+.BR chown (),
+.BR fchown (),
+and
+.BR lchown ()
+system calls supported only 16-bit user and group IDs.
+Subsequently, Linux 2.4 added
+.BR chown32 (),
+.BR fchown32 (),
+and
+.BR lchown32 (),
+supporting 32-bit IDs.
+The glibc
+.BR chown (),
+.BR fchown (),
+and
+.BR lchown ()
+wrapper functions transparently deal with the variations across kernel versions.
+.P
+Before Linux 2.1.81 (except 2.1.46),
+.BR chown ()
+did not follow symbolic links.
+Since Linux 2.1.81,
+.BR chown ()
+does follow symbolic links, and there is a new system call
+.BR lchown ()
+that does not follow symbolic links.
+Since Linux 2.1.86, this new call (that has the same semantics
+as the old
+.BR chown ())
+has got the same syscall number, and
+.BR chown ()
+got the newly introduced number.
+.SH EXAMPLES
+The following program changes the ownership of the file named in
+its second command-line argument to the value specified in its
+first command-line argument.
+The new owner can be specified either as a numeric user ID,
+or as a username (which is converted to a user ID by using
+.BR getpwnam (3)
+to perform a lookup in the system password file).
+.SS Program source
+.\" SRC BEGIN (chown.c)
+.EX
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    char           *endptr;
+    uid_t          uid;
+    struct passwd  *pwd;
+\&
+    if (argc != 3 || argv[1][0] == \[aq]\e0\[aq]) {
+        fprintf(stderr, "%s <owner> <file>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    uid = strtol(argv[1], &endptr, 10);  /* Allow a numeric string */
+\&
+    if (*endptr != \[aq]\e0\[aq]) {         /* Was not pure numeric string */
+        pwd = getpwnam(argv[1]);   /* Try getting UID for username */
+        if (pwd == NULL) {
+            perror("getpwnam");
+            exit(EXIT_FAILURE);
+        }
+\&
+        uid = pwd\->pw_uid;
+    }
+\&
+    if (chown(argv[2], uid, \-1) == \-1) {
+        perror("chown");
+        exit(EXIT_FAILURE);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR chgrp (1),
+.BR chown (1),
+.BR chmod (2),
+.BR flock (2),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/chown32.2 b/man/man2/chown32.2
new file mode 100644
index 000000000..f0a5635ae
--- /dev/null
+++ b/man/man2/chown32.2
@@ -0,0 +1 @@
+.so man2/chown.2
diff --git a/man/man2/chroot.2 b/man/man2/chroot.2
new file mode 100644
index 000000000..72a75fb40
--- /dev/null
+++ b/man/man2/chroot.2
@@ -0,0 +1,166 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1994-08-21 by Michael Chastain <mec@shell.portal.com>
+.\" Modified 1996-06-13 by aeb
+.\" Modified 1996-11-06 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1997-08-21 by Joseph S. Myers <jsm28@cam.ac.uk>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH chroot 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+chroot \- change root directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int chroot(const char *" path );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR chroot ():
+.nf
+    Since glibc 2.2.2:
+        _XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
+            || /* Since glibc 2.20: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE
+    Before glibc 2.2.2:
+        none
+.fi
+.SH DESCRIPTION
+.BR chroot ()
+changes the root directory of the calling process to that specified in
+.IR path .
+This directory will be used for pathnames beginning with \fI/\fP.
+The root directory is inherited by all children of the calling process.
+.P
+Only a privileged process (Linux: one with the
+.B CAP_SYS_CHROOT
+capability in its user namespace) may call
+.BR chroot ().
+.P
+This call changes an ingredient in the pathname resolution process
+and does nothing else.
+In particular, it is not intended to be used
+for any kind of security purpose, neither to fully sandbox a process nor
+to restrict filesystem system calls.
+In the past,
+.BR chroot ()
+has been used by daemons to restrict themselves prior to passing paths
+supplied by untrusted users to system calls such as
+.BR open (2).
+However, if a folder is moved out of the chroot directory, an attacker
+can exploit that to get out of the chroot directory as well.
+The easiest way to do that is to
+.BR chdir (2)
+to the to-be-moved directory, wait for it to be moved out, then open a
+path like ../../../etc/passwd.
+.P
+.\" This is how the "slightly trickier variation" works:
+.\" https://github.com/QubesOS/qubes-secpack/blob/master/QSBs/qsb-014-2015.txt#L142
+A slightly
+trickier variation also works under some circumstances if
+.BR chdir (2)
+is not permitted.
+If a daemon allows a "chroot directory" to be specified,
+that usually means that if you want to prevent remote users from accessing
+files outside the chroot directory, you must ensure that folders are never
+moved out of it.
+.P
+This call does not change the current working directory,
+so that after the call \[aq]\fI.\fP\[aq] can
+be outside the tree rooted at \[aq]\fI/\fP\[aq].
+In particular, the superuser can escape from a "chroot jail"
+by doing:
+.P
+.in +4n
+.EX
+mkdir foo; chroot foo; cd ..
+.EE
+.in
+.P
+This call does not close open file descriptors, and such file
+descriptors may allow access to files outside the chroot tree.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Depending on the filesystem, other errors can be returned.
+The more general errors are listed below:
+.TP
+.B EACCES
+Search permission is denied on a component of the path prefix.
+(See also
+.BR path_resolution (7).)
+.\" Also search permission is required on the final component,
+.\" maybe just to guarantee that it is a directory?
+.TP
+.B EFAULT
+.I path
+points outside your accessible address space.
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR path .
+.TP
+.B ENAMETOOLONG
+.I path
+is too long.
+.TP
+.B ENOENT
+The file does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of
+.I path
+is not a directory.
+.TP
+.B EPERM
+The caller has insufficient privilege.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4, 4.4BSD, SUSv2 (marked LEGACY).
+This function is not part of POSIX.1-2001.
+.\" SVr4 documents additional EINTR, ENOLINK and EMULTIHOP error conditions.
+.\" X/OPEN does not document EIO, ENOMEM or EFAULT error conditions.
+.SH NOTES
+A child process created via
+.BR fork (2)
+inherits its parent's root directory.
+The root directory is left unchanged by
+.BR execve (2).
+.P
+The magic symbolic link,
+.IR /proc/ pid /root ,
+can be used to discover a process's root directory; see
+.BR proc (5)
+for details.
+.P
+FreeBSD has a stronger
+.BR jail ()
+system call.
+.SH SEE ALSO
+.BR chroot (1),
+.BR chdir (2),
+.BR pivot_root (2),
+.BR path_resolution (7),
+.BR switch_root (8)
diff --git a/man/man2/clock_adjtime.2 b/man/man2/clock_adjtime.2
new file mode 100644
index 000000000..b08b9c801
--- /dev/null
+++ b/man/man2/clock_adjtime.2
@@ -0,0 +1 @@
+.so man2/adjtimex.2
diff --git a/man/man2/clock_getres.2 b/man/man2/clock_getres.2
new file mode 100644
index 000000000..9c98d12e9
--- /dev/null
+++ b/man/man2/clock_getres.2
@@ -0,0 +1,539 @@
+'\" t
+.\" Copyright (c) 2003 Nick Clifford (zaf@nrc.co.nz), Jan 25, 2003
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl), Aug 24, 2003
+.\" Copyright (c) 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2003-08-23 Martin Schulze <joey@infodrom.org> improvements
+.\" 2003-08-24 aeb, large parts rewritten
+.\" 2004-08-06 Christoph Lameter <clameter@sgi.com>, SMP note
+.\"
+.TH clock_getres 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clock_getres, clock_gettime, clock_settime \- clock and time functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc ),
+since glibc 2.17
+.P
+Before glibc 2.17,
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "int clock_getres(clockid_t " clockid ", struct timespec *_Nullable " res );
+.P
+.BI "int clock_gettime(clockid_t " clockid ", struct timespec *" tp );
+.BI "int clock_settime(clockid_t " clockid ", const struct timespec *" tp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR clock_getres (),
+.BR clock_gettime (),
+.BR clock_settime ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+The function
+.BR clock_getres ()
+finds the resolution (precision) of the specified clock
+.IR clockid ,
+and, if
+.I res
+is non-NULL, stores it in the \fIstruct timespec\fP pointed to by
+.IR res .
+The resolution of clocks depends on the implementation and cannot be
+configured by a particular process.
+If the time value pointed to by the argument
+.I tp
+of
+.BR clock_settime ()
+is not a multiple of
+.IR res ,
+then it is truncated to a multiple of
+.IR res .
+.P
+The functions
+.BR clock_gettime ()
+and
+.BR clock_settime ()
+retrieve and set the time of the specified clock
+.IR clockid .
+.P
+The
+.I res
+and
+.I tp
+arguments are
+.BR timespec (3)
+structures.
+.P
+The
+.I clockid
+argument is the identifier of the particular clock on which to act.
+A clock may be system-wide and hence visible for all processes, or
+per-process if it measures time only within a single process.
+.P
+All implementations support the system-wide real-time clock,
+which is identified by
+.BR CLOCK_REALTIME .
+Its time represents seconds and nanoseconds since the Epoch.
+When its time is changed, timers for a relative interval are
+unaffected, but timers for an absolute point in time are affected.
+.P
+More clocks may be implemented.
+The interpretation of the
+corresponding time values and the effect on timers is unspecified.
+.P
+Sufficiently recent versions of glibc and the Linux kernel
+support the following clocks:
+.TP
+.B CLOCK_REALTIME
+A settable system-wide clock that measures real (i.e., wall-clock) time.
+Setting this clock requires appropriate privileges.
+This clock is affected by discontinuous jumps in the system time
+(e.g., if the system administrator manually changes the clock),
+and by frequency adjustments performed by NTP and similar applications via
+.BR adjtime (3),
+.BR adjtimex (2),
+.BR clock_adjtime (2),
+and
+.BR ntp_adjtime (3).
+This clock normally counts the number of seconds since
+1970-01-01 00:00:00 Coordinated Universal Time (UTC)
+except that it ignores leap seconds;
+near a leap second it is typically adjusted by NTP
+to stay roughly in sync with UTC.
+.TP
+.BR CLOCK_REALTIME_ALARM " (since Linux 3.0; Linux-specific)"
+Like
+.BR CLOCK_REALTIME ,
+but not settable.
+See
+.BR timer_create (2)
+for further details.
+.TP
+.BR CLOCK_REALTIME_COARSE " (since Linux 2.6.32; Linux-specific)"
+.\" Added in commit da15cfdae03351c689736f8d142618592e3cebc3
+A faster but less precise version of
+.BR CLOCK_REALTIME .
+This clock is not settable.
+Use when you need very fast, but not fine-grained timestamps.
+Requires per-architecture support,
+and probably also architecture support for this flag in the
+.BR vdso (7).
+.TP
+.BR CLOCK_TAI " (since Linux 3.10; Linux-specific)"
+.\" commit 1ff3c9677bff7e468e0c487d0ffefe4e901d33f4
+A nonsettable system-wide clock derived from wall-clock time
+but counting leap seconds.
+This clock does
+not experience discontinuities or frequency adjustments caused by
+inserting leap seconds as
+.B CLOCK_REALTIME
+does.
+.IP
+The acronym TAI refers to International Atomic Time.
+.TP
+.B CLOCK_MONOTONIC
+A nonsettable system-wide clock that
+represents monotonic time since\[em]as described
+by POSIX\[em]"some unspecified point in the past".
+On Linux, that point corresponds to the number of seconds that the system
+has been running since it was booted.
+.IP
+The
+.B CLOCK_MONOTONIC
+clock is not affected by discontinuous jumps in the system time
+(e.g., if the system administrator manually changes the clock),
+but is affected by frequency adjustments.
+This clock does not count time that the system is suspended.
+All
+.B CLOCK_MONOTONIC
+variants guarantee that the time returned by consecutive calls will not go
+backwards, but successive calls may\[em]depending on the architecture\[em]return
+identical (not-increased) time values.
+.TP
+.BR CLOCK_MONOTONIC_COARSE " (since Linux 2.6.32; Linux-specific)"
+.\" Added in commit da15cfdae03351c689736f8d142618592e3cebc3
+A faster but less precise version of
+.BR CLOCK_MONOTONIC .
+Use when you need very fast, but not fine-grained timestamps.
+Requires per-architecture support,
+and probably also architecture support for this flag in the
+.BR vdso (7).
+.TP
+.BR CLOCK_MONOTONIC_RAW " (since Linux 2.6.28; Linux-specific)"
+.\" Added in commit 2d42244ae71d6c7b0884b5664cf2eda30fb2ae68, John Stultz
+Similar to
+.BR CLOCK_MONOTONIC ,
+but provides access to a raw hardware-based time
+that is not subject to frequency adjustments.
+This clock does not count time that the system is suspended.
+.TP
+.BR CLOCK_BOOTTIME " (since Linux 2.6.39; Linux-specific)"
+.\" commit 7fdd7f89006dd5a4c702fa0ce0c272345fa44ae0
+.\" commit 70a08cca1227dc31c784ec930099a4417a06e7d0
+A nonsettable system-wide clock that is identical to
+.BR CLOCK_MONOTONIC ,
+except that it also includes any time that the system is suspended.
+This allows applications to get a suspend-aware monotonic clock
+without having to deal with the complications of
+.BR CLOCK_REALTIME ,
+which may have discontinuities if the time is changed using
+.BR settimeofday (2)
+or similar.
+.TP
+.BR CLOCK_BOOTTIME_ALARM " (since Linux 3.0; Linux-specific)"
+Like
+.BR CLOCK_BOOTTIME .
+See
+.BR timer_create (2)
+for further details.
+.TP
+.BR CLOCK_PROCESS_CPUTIME_ID " (since Linux 2.6.12)"
+This is a clock that measures CPU time consumed by this process
+(i.e., CPU time consumed by all threads in the process).
+On Linux, this clock is not settable.
+.TP
+.BR CLOCK_THREAD_CPUTIME_ID " (since Linux 2.6.12)"
+This is a clock that measures CPU time consumed by this thread.
+On Linux, this clock is not settable.
+.P
+Linux also implements dynamic clock instances as described below.
+.SS Dynamic clocks
+In addition to the hard-coded System-V style clock IDs described above,
+Linux also supports
+POSIX clock operations on certain character devices.
+Such devices are
+called "dynamic" clocks, and are supported since Linux 2.6.39.
+.P
+Using the appropriate macros, open file
+descriptors may be converted into clock IDs and passed to
+.BR clock_gettime (),
+.BR clock_settime (),
+and
+.BR clock_adjtime (2).
+The following example shows how to convert a file descriptor into a
+dynamic clock ID.
+.P
+.in +4n
+.EX
+#define CLOCKFD 3
+#define FD_TO_CLOCKID(fd)   ((\[ti](clockid_t) (fd) << 3) | CLOCKFD)
+#define CLOCKID_TO_FD(clk)  ((unsigned int) \[ti]((clk) >> 3))
+\&
+struct timespec ts;
+clockid_t clkid;
+int fd;
+\&
+fd = open("/dev/ptp0", O_RDWR);
+clkid = FD_TO_CLOCKID(fd);
+clock_gettime(clkid, &ts);
+.EE
+.in
+.SH RETURN VALUE
+.BR clock_gettime (),
+.BR clock_settime (),
+and
+.BR clock_getres ()
+return 0 for success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.BR clock_settime ()
+does not have write permission for the dynamic POSIX
+clock device indicated.
+.TP
+.B EFAULT
+.I tp
+points outside the accessible address space.
+.TP
+.B EINVAL
+The
+.I clockid
+specified is invalid for one of two reasons.
+Either the System-V style
+hard coded positive value is out of range, or the dynamic clock ID
+does not refer to a valid instance of a clock object.
+.\" Linux also gives this error on attempts to set CLOCK_PROCESS_CPUTIME_ID
+.\" and CLOCK_THREAD_CPUTIME_ID, when probably the proper error should be
+.\" EPERM.
+.TP
+.B EINVAL
+.RB ( clock_settime ()):
+.I tp.tv_sec
+is negative or
+.I tp.tv_nsec
+is outside the range [0, 999,999,999].
+.TP
+.B EINVAL
+The
+.I clockid
+specified in a call to
+.BR clock_settime ()
+is not a settable clock.
+.TP
+.BR EINVAL " (since Linux 4.3)"
+.\" commit e1d7ba8735551ed79c7a0463a042353574b96da3
+A call to
+.BR clock_settime ()
+with a
+.I clockid
+of
+.B CLOCK_REALTIME
+attempted to set the time to a value less than
+the current value of the
+.B CLOCK_MONOTONIC
+clock.
+.TP
+.B ENODEV
+The hot-pluggable device (like USB for example) represented by a
+dynamic
+.I clk_id
+has disappeared after its character device was opened.
+.TP
+.B ENOTSUP
+The operation is not supported by the dynamic POSIX clock device
+specified.
+.TP
+.B EOVERFLOW
+The timestamp would not fit in
+.I time_t
+range.
+This can happen if an executable with 32-bit
+.I time_t
+is run on a 64-bit kernel when the time is 2038-01-19 03:14:08 UTC or later.
+However, when the system time is out of
+.I time_t
+range in other situations, the behavior is undefined.
+.TP
+.B EPERM
+.BR clock_settime ()
+does not have permission to set the clock indicated.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR clock_getres (),
+.BR clock_gettime (),
+.BR clock_settime ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+POSIX.1 specifies the following:
+.RS
+.P
+Setting the value of the
+.B CLOCK_REALTIME
+clock via
+.BR clock_settime ()
+shall have no effect on threads that are blocked waiting for a relative time
+service based upon this clock, including the
+.BR nanosleep ()
+function; nor on the expiration of relative timers based upon this clock.
+Consequently, these time services shall expire when the requested relative
+interval elapses, independently of the new or old value of the clock.
+.RE
+.P
+According to POSIX.1-2001, a process with "appropriate privileges" may set the
+.B CLOCK_PROCESS_CPUTIME_ID
+and
+.B CLOCK_THREAD_CPUTIME_ID
+clocks using
+.BR clock_settime ().
+On Linux, these clocks are not settable
+(i.e., no process has "appropriate privileges").
+.\" See http://bugzilla.kernel.org/show_bug.cgi?id=11972
+.SS C library/kernel differences
+On some architectures, an implementation of
+.BR clock_gettime ()
+is provided in the
+.BR vdso (7).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SUSv2.
+Linux 2.6.
+.P
+On POSIX systems on which these functions are available, the symbol
+.B _POSIX_TIMERS
+is defined in \fI<unistd.h>\fP to a value greater than 0.
+POSIX.1-2008 makes these functions mandatory.
+.P
+The symbols
+.BR _POSIX_MONOTONIC_CLOCK ,
+.BR _POSIX_CPUTIME ,
+.B _POSIX_THREAD_CPUTIME
+indicate that
+.BR CLOCK_MONOTONIC ,
+.BR CLOCK_PROCESS_CPUTIME_ID ,
+.B CLOCK_THREAD_CPUTIME_ID
+are available.
+(See also
+.BR sysconf (3).)
+.\"
+.SS Historical note for SMP systems
+Before Linux added kernel support for
+.B CLOCK_PROCESS_CPUTIME_ID
+and
+.BR CLOCK_THREAD_CPUTIME_ID ,
+glibc implemented these clocks on many platforms using timer
+registers from the CPUs
+(TSC on i386, AR.ITC on Itanium).
+These registers may differ between CPUs and as a consequence
+these clocks may return
+.B bogus results
+if a process is migrated to another CPU.
+.P
+If the CPUs in an SMP system have different clock sources, then
+there is no way to maintain a correlation between the timer registers since
+each CPU will run at a slightly different frequency.
+If that is the case, then
+.I clock_getcpuclockid(0)
+will return
+.B ENOENT
+to signify this condition.
+The two clocks will then be useful only if it
+can be ensured that a process stays on a certain CPU.
+.P
+The processors in an SMP system do not start all at exactly the same
+time and therefore the timer registers are typically running at an offset.
+Some architectures include code that attempts to limit these offsets on bootup.
+However, the code cannot guarantee to accurately tune the offsets.
+glibc contains no provisions to deal with these offsets (unlike the Linux
+Kernel).
+Typically these offsets are small and therefore the effects may be
+negligible in most cases.
+.P
+Since glibc 2.4,
+the wrapper functions for the system calls described in this page avoid
+the abovementioned problems by employing the kernel implementation of
+.B CLOCK_PROCESS_CPUTIME_ID
+and
+.BR CLOCK_THREAD_CPUTIME_ID ,
+on systems that provide such an implementation
+(i.e., Linux 2.6.12 and later).
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR clock_gettime ()
+and
+.BR clock_getres ()
+with various clocks.
+This is an example of what we might see when running the program:
+.P
+.in +4n
+.EX
+$ \fB./clock_times x\fP
+CLOCK_REALTIME : 1585985459.446 (18356 days +  7h 30m 59s)
+     resolution:          0.000000001
+CLOCK_TAI      : 1585985496.447 (18356 days +  7h 31m 36s)
+     resolution:          0.000000001
+CLOCK_MONOTONIC:      52395.722 (14h 33m 15s)
+     resolution:          0.000000001
+CLOCK_BOOTTIME :      72691.019 (20h 11m 31s)
+     resolution:          0.000000001
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (clock_getres.c)
+.EX
+/* clock_times.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#define _XOPEN_SOURCE 600
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+\&
+#define SECS_IN_DAY (24 * 60 * 60)
+\&
+static void
+displayClock(clockid_t clock, const char *name, bool showRes)
+{
+    long             days;
+    struct timespec  ts;
+\&
+    if (clock_gettime(clock, &ts) == \-1) {
+        perror("clock_gettime");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("%\-15s: %10jd.%03ld (", name,
+           (intmax_t) ts.tv_sec, ts.tv_nsec / 1000000);
+\&
+    days = ts.tv_sec / SECS_IN_DAY;
+    if (days > 0)
+        printf("%ld days + ", days);
+\&
+    printf("%2dh %2dm %2ds",
+           (int) (ts.tv_sec % SECS_IN_DAY) / 3600,
+           (int) (ts.tv_sec % 3600) / 60,
+           (int) ts.tv_sec % 60);
+    printf(")\en");
+\&
+    if (clock_getres(clock, &ts) == \-1) {
+        perror("clock_getres");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (showRes)
+        printf("     resolution: %10jd.%09ld\en",
+               (intmax_t) ts.tv_sec, ts.tv_nsec);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    bool showRes = argc > 1;
+\&
+    displayClock(CLOCK_REALTIME, "CLOCK_REALTIME", showRes);
+#ifdef CLOCK_TAI
+    displayClock(CLOCK_TAI, "CLOCK_TAI", showRes);
+#endif
+    displayClock(CLOCK_MONOTONIC, "CLOCK_MONOTONIC", showRes);
+#ifdef CLOCK_BOOTTIME
+    displayClock(CLOCK_BOOTTIME, "CLOCK_BOOTTIME", showRes);
+#endif
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR date (1),
+.BR gettimeofday (2),
+.BR settimeofday (2),
+.BR time (2),
+.BR adjtime (3),
+.BR clock_getcpuclockid (3),
+.BR ctime (3),
+.BR ftime (3),
+.BR pthread_getcpuclockid (3),
+.BR sysconf (3),
+.BR timespec (3),
+.BR time (7),
+.BR time_namespaces (7),
+.BR vdso (7),
+.BR hwclock (8)
diff --git a/man/man2/clock_gettime.2 b/man/man2/clock_gettime.2
new file mode 100644
index 000000000..5a599b4b9
--- /dev/null
+++ b/man/man2/clock_gettime.2
@@ -0,0 +1 @@
+.so man2/clock_getres.2
diff --git a/man/man2/clock_nanosleep.2 b/man/man2/clock_nanosleep.2
new file mode 100644
index 000000000..7715ec385
--- /dev/null
+++ b/man/man2/clock_nanosleep.2
@@ -0,0 +1,253 @@
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\" <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH clock_nanosleep 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clock_nanosleep \- high-resolution sleep with specifiable clock
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc ),
+since glibc 2.17
+.P
+Before glibc 2.17,
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.B #include <time.h>
+.nf
+.P
+.BI "int clock_nanosleep(clockid_t " clockid ", int " flags ,
+.BI "                    const struct timespec *" t ,
+.BI "                    struct timespec *_Nullable " remain );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR clock_nanosleep ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+Like
+.BR nanosleep (2),
+.BR clock_nanosleep ()
+allows the calling thread to sleep for an interval specified
+with nanosecond precision.
+It differs in allowing the caller to select the clock against
+which the sleep interval is to be measured,
+and in allowing the sleep interval to be specified as
+either an absolute or a relative value.
+.P
+The time values passed to and returned by this call are specified using
+.BR timespec (3)
+structures.
+.P
+The
+.I clockid
+argument specifies the clock against which the sleep interval
+is to be measured.
+This argument can have one of the following values:
+.\" Look in time/posix-timers.c (kernel 5.6 sources) for the
+.\" 'struct k_clock' structures that have an 'nsleep' method
+.TP
+.B CLOCK_REALTIME
+A settable system-wide real-time clock.
+.TP
+.BR CLOCK_TAI " (since Linux 3.10)"
+A system-wide clock derived from wall-clock time but counting leap seconds.
+.TP
+.B CLOCK_MONOTONIC
+A nonsettable, monotonically increasing clock that measures time
+since some unspecified point in the past that does not change after
+system startup.
+.\" On Linux this clock measures time since boot.
+.TP
+.BR CLOCK_BOOTTIME " (since Linux 2.6.39)"
+Identical to
+.BR CLOCK_MONOTONIC ,
+except that it also includes any time that the system is suspended.
+.TP
+.B CLOCK_PROCESS_CPUTIME_ID
+A settable per-process clock that measures CPU time consumed
+by all threads in the process.
+.\" There is some trickery between glibc and the kernel
+.\" to deal with the CLOCK_PROCESS_CPUTIME_ID case.
+.P
+See
+.BR clock_getres (2)
+for further details on these clocks.
+In addition, the CPU clock IDs returned by
+.BR clock_getcpuclockid (3)
+and
+.BR pthread_getcpuclockid (3)
+can also be passed in
+.IR clockid .
+.\" Sleeping against CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM
+.\" is also possible (tested), with CAP_WAKE_ALARM, but I'm not
+.\" sure if this is useful or needs to be documented.
+.P
+If
+.I flags
+is 0, then the value specified in
+.I t
+is interpreted as an interval relative to the current
+value of the clock specified by
+.IR clockid .
+.P
+If
+.I flags
+is
+.BR TIMER_ABSTIME ,
+then
+.I t
+is interpreted as an absolute time as measured by the clock,
+.IR clockid .
+If
+.I t
+is less than or equal to the current value of the clock,
+then
+.BR clock_nanosleep ()
+returns immediately without suspending the calling thread.
+.P
+.BR clock_nanosleep ()
+suspends the execution of the calling thread
+until either at least the time specified by
+.I t
+has elapsed,
+or a signal is delivered that causes a signal handler to be called or
+that terminates the process.
+.P
+If the call is interrupted by a signal handler,
+.BR clock_nanosleep ()
+fails with the error
+.BR EINTR .
+In addition, if
+.I remain
+is not NULL, and
+.I flags
+was not
+.BR TIMER_ABSTIME ,
+it returns the remaining unslept time in
+.IR remain .
+This value can then be used to call
+.BR clock_nanosleep ()
+again and complete a (relative) sleep.
+.SH RETURN VALUE
+On successfully sleeping for the requested interval,
+.BR clock_nanosleep ()
+returns 0.
+If the call is interrupted by a signal handler or encounters an error,
+then it returns one of the positive error number listed in ERRORS.
+.SH ERRORS
+.TP
+.B EFAULT
+.I t
+or
+.I remain
+specified an invalid address.
+.TP
+.B EINTR
+The sleep was interrupted by a signal handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+The value in the
+.I tv_nsec
+field was not in the range [0, 999999999] or
+.I tv_sec
+was negative.
+.TP
+.B EINVAL
+.I clockid
+was invalid.
+.RB ( CLOCK_THREAD_CPUTIME_ID
+is not a permitted value for
+.IR clockid .)
+.TP
+.B ENOTSUP
+The kernel does not support sleeping against this
+.IR clockid .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+Linux 2.6,
+glibc 2.1.
+.SH NOTES
+If the interval specified in
+.I t
+is not an exact multiple of the granularity underlying clock (see
+.BR time (7)),
+then the interval will be rounded up to the next multiple.
+Furthermore, after the sleep completes, there may still be a delay before
+the CPU becomes free to once again execute the calling thread.
+.P
+Using an absolute timer is useful for preventing
+timer drift problems of the type described in
+.BR nanosleep (2).
+(Such problems are exacerbated in programs that try to restart
+a relative sleep that is repeatedly interrupted by signals.)
+To perform a relative sleep that avoids these problems, call
+.BR clock_gettime (2)
+for the desired clock,
+add the desired interval to the returned time value,
+and then call
+.BR clock_nanosleep ()
+with the
+.B TIMER_ABSTIME
+flag.
+.P
+.BR clock_nanosleep ()
+is never restarted after being interrupted by a signal handler,
+regardless of the use of the
+.BR sigaction (2)
+.B SA_RESTART
+flag.
+.P
+The
+.I remain
+argument is unused, and unnecessary, when
+.I flags
+is
+.BR TIMER_ABSTIME .
+(An absolute sleep can be restarted using the same
+.I t
+argument.)
+.P
+POSIX.1 specifies that
+.BR clock_nanosleep ()
+has no effect on signals dispositions or the signal mask.
+.P
+POSIX.1 specifies that after changing the value of the
+.B CLOCK_REALTIME
+clock via
+.BR clock_settime (2),
+the new clock value shall be used to determine the time
+at which a thread blocked on an absolute
+.BR clock_nanosleep ()
+will wake up;
+if the new clock value falls past the end of the sleep interval, then the
+.BR clock_nanosleep ()
+call will return immediately.
+.P
+POSIX.1 specifies that
+changing the value of the
+.B CLOCK_REALTIME
+clock via
+.BR clock_settime (2)
+shall have no effect on a thread that is blocked on a relative
+.BR clock_nanosleep ().
+.SH SEE ALSO
+.BR clock_getres (2),
+.BR nanosleep (2),
+.BR restart_syscall (2),
+.BR timer_create (2),
+.BR sleep (3),
+.BR timespec (3),
+.BR usleep (3),
+.BR time (7)
diff --git a/man/man2/clock_settime.2 b/man/man2/clock_settime.2
new file mode 100644
index 000000000..5a599b4b9
--- /dev/null
+++ b/man/man2/clock_settime.2
@@ -0,0 +1 @@
+.so man2/clock_getres.2
diff --git a/man/man2/clone.2 b/man/man2/clone.2
new file mode 100644
index 000000000..e88c54eeb
--- /dev/null
+++ b/man/man2/clone.2
@@ -0,0 +1,1949 @@
+'\" t
+.\" Copyright (c) 1992 Drew Eckhardt <drew@cs.colorado.edu>, March 28, 1992
+.\" and Copyright (c) Michael Kerrisk, 2001, 2002, 2005, 2013, 2019
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 24 Jul 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 21 Aug 1994 by Michael Chastain <mec@shell.portal.com>:
+.\"   New man page (copied from 'fork.2').
+.\" Modified 10 June 1995 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 25 April 1998 by Xavier Leroy <Xavier.Leroy@inria.fr>
+.\" Modified 26 Jun 2001 by Michael Kerrisk
+.\"     Mostly upgraded to Linux 2.4.x
+.\"     Added prototype for sys_clone() plus description
+.\"	Added CLONE_THREAD with a brief description of thread groups
+.\"	Added CLONE_PARENT and revised entire page remove ambiguity
+.\"		between "calling process" and "parent process"
+.\"	Added CLONE_PTRACE and CLONE_VFORK
+.\"	Added EPERM and EINVAL error codes
+.\"	Renamed "__clone" to "clone" (which is the prototype in <sched.h>)
+.\"	various other minor tidy ups and clarifications.
+.\" Modified 26 Jun 2001 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Updated notes for 2.4.7+ behavior of CLONE_THREAD
+.\" Modified 15 Oct 2002 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added description for CLONE_NEWNS, which was added in Linux 2.4.19
+.\" Slightly rephrased, aeb.
+.\" Modified 1 Feb 2003 - added CLONE_SIGHAND restriction, aeb.
+.\" Modified 1 Jan 2004 - various updates, aeb
+.\" Modified 2004-09-10 - added CLONE_PARENT_SETTID etc. - aeb.
+.\" 2005-04-12, mtk, noted the PID caching behavior of NPTL's getpid()
+.\"	wrapper under BUGS.
+.\" 2005-05-10, mtk, added CLONE_SYSVSEM, CLONE_UNTRACED, CLONE_STOPPED.
+.\" 2005-05-17, mtk, Substantially enhanced discussion of CLONE_THREAD.
+.\" 2008-11-18, mtk, order CLONE_* flags alphabetically
+.\" 2008-11-18, mtk, document CLONE_NEWPID
+.\" 2008-11-19, mtk, document CLONE_NEWUTS
+.\" 2008-11-19, mtk, document CLONE_NEWIPC
+.\" 2008-11-19, Jens Axboe, mtk, document CLONE_IO
+.\"
+.TH clone 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clone, __clone2, clone3 \- create a child process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+/* Prototype for the glibc wrapper function */
+.P
+.B #define _GNU_SOURCE
+.B #include <sched.h>
+.P
+.BI "int clone(int (*" "fn" ")(void *_Nullable), void *" stack \
+", int " flags ,
+.BI "          void *_Nullable " "arg" ", ..." \
+"  \fR/*\fP" " pid_t *_Nullable " parent_tid ,
+.BI "                                       void *_Nullable " tls ,
+.BI "                                       pid_t *_Nullable " child_tid " \fR*/\fP );"
+.P
+/* For the prototype of the raw clone() system call, see NOTES */
+.P
+.BR "#include <linux/sched.h>" "    /* Definition of " "struct clone_args" " */"
+.BR "#include <sched.h>" "          /* Definition of " CLONE_* " constants */"
+.BR "#include <sys/syscall.h>" "    /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(SYS_clone3, struct clone_args *" cl_args ", size_t " size );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR clone3 (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+These system calls
+create a new ("child") process, in a manner similar to
+.BR fork (2).
+.P
+By contrast with
+.BR fork (2),
+these system calls provide more precise control over what pieces of execution
+context are shared between the calling process and the child process.
+For example, using these system calls, the caller can control whether
+or not the two processes share the virtual address space,
+the table of file descriptors, and the table of signal handlers.
+These system calls also allow the new child process to be placed
+in separate
+.BR namespaces (7).
+.P
+Note that in this manual
+page, "calling process" normally corresponds to "parent process".
+But see the descriptions of
+.B CLONE_PARENT
+and
+.B CLONE_THREAD
+below.
+.P
+This page describes the following interfaces:
+.IP \[bu] 3
+The glibc
+.BR clone ()
+wrapper function and the underlying system call on which it is based.
+The main text describes the wrapper function;
+the differences for the raw system call
+are described toward the end of this page.
+.IP \[bu]
+The newer
+.BR clone3 ()
+system call.
+.P
+In the remainder of this page, the terminology "the clone call" is used
+when noting details that apply to all of these interfaces.
+.\"
+.SS The clone() wrapper function
+When the child process is created with the
+.BR clone ()
+wrapper function,
+it commences execution by calling the function pointed to by the argument
+.IR fn .
+(This differs from
+.BR fork (2),
+where execution continues in the child from the point
+of the
+.BR fork (2)
+call.)
+The
+.I arg
+argument is passed as the argument of the function
+.IR fn .
+.P
+When the
+.IR fn ( arg )
+function returns, the child process terminates.
+The integer returned by
+.I fn
+is the exit status for the child process.
+The child process may also terminate explicitly by calling
+.BR exit (2)
+or after receiving a fatal signal.
+.P
+The
+.I stack
+argument specifies the location of the stack used by the child process.
+Since the child and calling process may share memory,
+it is not possible for the child process to execute in the
+same stack as the calling process.
+The calling process must therefore
+set up memory space for the child stack and pass a pointer to this
+space to
+.BR clone ().
+Stacks grow downward on all processors that run Linux
+(except the HP PA processors), so
+.I stack
+usually points to the topmost address of the memory space set up for
+the child stack.
+Note that
+.BR clone ()
+does not provide a means whereby the caller can inform the kernel of the
+size of the stack area.
+.P
+The remaining arguments to
+.BR clone ()
+are discussed below.
+.\"
+.SS clone3()
+The
+.BR clone3 ()
+system call provides a superset of the functionality of the older
+.BR clone ()
+interface.
+It also provides a number of API improvements, including:
+space for additional flags bits;
+cleaner separation in the use of various arguments;
+and the ability to specify the size of the child's stack area.
+.P
+As with
+.BR fork (2),
+.BR clone3 ()
+returns in both the parent and the child.
+It returns 0 in the child process and returns the PID of the child
+in the parent.
+.P
+The
+.I cl_args
+argument of
+.BR clone3 ()
+is a structure of the following form:
+.P
+.in +4n
+.EX
+struct clone_args {
+    u64 flags;        /* Flags bit mask */
+    u64 pidfd;        /* Where to store PID file descriptor
+                         (\fIint *\fP) */
+    u64 child_tid;    /* Where to store child TID,
+                         in child\[aq]s memory (\fIpid_t *\fP) */
+    u64 parent_tid;   /* Where to store child TID,
+                         in parent\[aq]s memory (\fIpid_t *\fP) */
+    u64 exit_signal;  /* Signal to deliver to parent on
+                         child termination */
+    u64 stack;        /* Pointer to lowest byte of stack */
+    u64 stack_size;   /* Size of stack */
+    u64 tls;          /* Location of new TLS */
+    u64 set_tid;      /* Pointer to a \fIpid_t\fP array
+                         (since Linux 5.5) */
+    u64 set_tid_size; /* Number of elements in \fIset_tid\fP
+                         (since Linux 5.5) */
+    u64 cgroup;       /* File descriptor for target cgroup
+                         of child (since Linux 5.7) */
+};
+.EE
+.in
+.P
+The
+.I size
+argument that is supplied to
+.BR clone3 ()
+should be initialized to the size of this structure.
+(The existence of the
+.I size
+argument permits future extensions to the
+.I clone_args
+structure.)
+.P
+The stack for the child process is specified via
+.IR cl_args.stack ,
+which points to the lowest byte of the stack area,
+and
+.IR cl_args.stack_size ,
+which specifies the size of the stack in bytes.
+In the case where the
+.B CLONE_VM
+flag (see below) is specified, a stack must be explicitly allocated
+and specified.
+Otherwise, these two fields can be specified as NULL and 0,
+which causes the child to use the same stack area as the parent
+(in the child's own virtual address space).
+.P
+The remaining fields in the
+.I cl_args
+argument are discussed below.
+.\"
+.SS Equivalence between clone() and clone3() arguments
+Unlike the older
+.BR clone ()
+interface, where arguments are passed individually, in the newer
+.BR clone3 ()
+interface the arguments are packaged into the
+.I clone_args
+structure shown above.
+This structure allows for a superset of the information passed via the
+.BR clone ()
+arguments.
+.P
+The following table shows the equivalence between the arguments of
+.BR clone ()
+and the fields in the
+.I clone_args
+argument supplied to
+.BR clone3 ():
+.RS 4
+.TS
+lb lb lb
+l l l
+li li l.
+clone()	clone3()	Notes
+	\fIcl_args\fP field
+flags & \[ti]0xff	flags	T{
+For most flags; details below
+T}
+parent_tid	pidfd	See CLONE_PIDFD
+child_tid	child_tid	See CLONE_CHILD_SETTID
+parent_tid	parent_tid	See CLONE_PARENT_SETTID
+flags & 0xff	exit_signal
+stack	stack
+\fP---\fP	stack_size
+tls	tls	See CLONE_SETTLS
+\fP---\fP	set_tid	See below for details
+\fP---\fP	set_tid_size
+\fP---\fP	cgroup	See CLONE_INTO_CGROUP
+.TE
+.RE
+.\"
+.SS The child termination signal
+When the child process terminates, a signal may be sent to the parent.
+The termination signal is specified in the low byte of
+.I flags
+.RB ( clone ())
+or in
+.I cl_args.exit_signal
+.RB ( clone3 ()).
+If this signal is specified as anything other than
+.BR SIGCHLD ,
+then the parent process must specify the
+.B __WALL
+or
+.B __WCLONE
+options when waiting for the child with
+.BR wait (2).
+If no signal (i.e., zero) is specified, then the parent process is not signaled
+when the child terminates.
+.\"
+.SS The set_tid array
+By default, the kernel chooses the next sequential PID for the new
+process in each of the PID namespaces where it is present.
+When creating a process with
+.BR clone3 (),
+the
+.I set_tid
+array (available since Linux 5.5)
+can be used to select specific PIDs for the process in some
+or all of the PID namespaces where it is present.
+If the PID of the newly created process should be set only for the current
+PID namespace or in the newly created PID namespace (if
+.I flags
+contains
+.BR CLONE_NEWPID )
+then the first element in the
+.I set_tid
+array has to be the desired PID and
+.I set_tid_size
+needs to be 1.
+.P
+If the PID of the newly created process should have a certain value in
+multiple PID namespaces, then the
+.I set_tid
+array can have multiple entries.
+The first entry defines the PID in the most
+deeply nested PID namespace and each of the following entries contains
+the PID in the
+corresponding ancestor PID namespace.
+The number of PID namespaces in which a PID
+should be set is defined by
+.I set_tid_size
+which cannot be larger than the number of currently nested PID namespaces.
+.P
+To create a process with the following PIDs in a PID namespace hierarchy:
+.RS 4
+.TS
+lb lb lb
+l l l.
+PID NS level	Requested PID	Notes
+0	31496	Outermost PID namespace
+1	42
+2	7	Innermost PID namespace
+.TE
+.RE
+.P
+Set the array to:
+.P
+.in +4n
+.EX
+set_tid[0] = 7;
+set_tid[1] = 42;
+set_tid[2] = 31496;
+set_tid_size = 3;
+.EE
+.in
+.P
+If only the PIDs in the two innermost PID namespaces
+need to be specified, set the array to:
+.P
+.in +4n
+.EX
+set_tid[0] = 7;
+set_tid[1] = 42;
+set_tid_size = 2;
+.EE
+.in
+.P
+The PID in the PID namespaces outside the two innermost PID namespaces
+is selected the same way as any other PID is selected.
+.P
+The
+.I set_tid
+feature requires
+.B CAP_SYS_ADMIN
+or
+(since Linux 5.9)
+.\" commit 124ea650d3072b005457faed69909221c2905a1f
+.\" commit 1caef81da05a84a40dbf02110e967ce6d1135ff6
+.B CAP_CHECKPOINT_RESTORE
+in all owning user namespaces of the target PID namespaces.
+.P
+Callers may only choose a PID greater than 1 in a given PID namespace
+if an
+.B init
+process (i.e., a process with PID 1) already exists in that namespace.
+Otherwise the PID
+entry for this PID namespace must be 1.
+.\"
+.SS The flags mask
+Both
+.BR clone ()
+and
+.BR clone3 ()
+allow a flags bit mask that modifies their behavior
+and allows the caller to specify what is shared between the calling process
+and the child process.
+This bit mask\[em]the
+.I flags
+argument of
+.BR clone ()
+or the
+.I cl_args.flags
+field passed to
+.BR clone3 ()\[em]is
+referred to as the
+.I flags
+mask in the remainder of this page.
+.P
+The
+.I flags
+mask is specified as a bitwise OR of zero or more of
+the constants listed below.
+Except as noted below, these flags are available
+(and have the same effect) in both
+.BR clone ()
+and
+.BR clone3 ().
+.TP
+.BR CLONE_CHILD_CLEARTID " (since Linux 2.5.49)"
+Clear (zero) the child thread ID at the location pointed to by
+.I child_tid
+.RB ( clone ())
+or
+.I cl_args.child_tid
+.RB ( clone3 ())
+in child memory when the child exits, and do a wakeup on the futex
+at that address.
+The address involved may be changed by the
+.BR set_tid_address (2)
+system call.
+This is used by threading libraries.
+.TP
+.BR CLONE_CHILD_SETTID " (since Linux 2.5.49)"
+Store the child thread ID at the location pointed to by
+.I child_tid
+.RB ( clone ())
+or
+.I cl_args.child_tid
+.RB ( clone3 ())
+in the child's memory.
+The store operation completes before the clone call
+returns control to user space in the child process.
+(Note that the store operation may not have completed before the clone call
+returns in the parent process, which is relevant if the
+.B CLONE_VM
+flag is also employed.)
+.TP
+.BR CLONE_CLEAR_SIGHAND " (since Linux 5.5)"
+.\" commit b612e5df4587c934bd056bf05f4a1deca4de4f75
+By default, signal dispositions in the child thread are the same as
+in the parent.
+If this flag is specified,
+then all signals that are handled in the parent
+(and not set to
+.BR SIG_IGN )
+are reset to their default dispositions
+.RB ( SIG_DFL )
+in the child.
+.IP
+Specifying this flag together with
+.B CLONE_SIGHAND
+is nonsensical and disallowed.
+.TP
+.BR CLONE_DETACHED " (historical)"
+For a while (during the Linux 2.5 development series)
+.\" added in Linux 2.5.32; removed in Linux 2.6.0-test4
+there was a
+.B CLONE_DETACHED
+flag,
+which caused the parent not to receive a signal when the child terminated.
+Ultimately, the effect of this flag was subsumed under the
+.B CLONE_THREAD
+flag and by the time Linux 2.6.0 was released, this flag had no effect.
+Starting in Linux 2.6.2, the need to give this flag together with
+.B CLONE_THREAD
+disappeared.
+.IP
+This flag is still defined, but it is usually ignored when calling
+.BR clone ().
+However, see the description of
+.B CLONE_PIDFD
+for some exceptions.
+.TP
+.BR CLONE_FILES " (since Linux 2.0)"
+If
+.B CLONE_FILES
+is set, the calling process and the child process share the same file
+descriptor table.
+Any file descriptor created by the calling process or by the child
+process is also valid in the other process.
+Similarly, if one of the processes closes a file descriptor,
+or changes its associated flags (using the
+.BR fcntl (2)
+.B F_SETFD
+operation), the other process is also affected.
+If a process sharing a file descriptor table calls
+.BR execve (2),
+its file descriptor table is duplicated (unshared).
+.IP
+If
+.B CLONE_FILES
+is not set, the child process inherits a copy of all file descriptors
+opened in the calling process at the time of the clone call.
+Subsequent operations that open or close file descriptors,
+or change file descriptor flags,
+performed by either the calling
+process or the child process do not affect the other process.
+Note, however,
+that the duplicated file descriptors in the child refer to the same
+open file descriptions as the corresponding file descriptors
+in the calling process,
+and thus share file offsets and file status flags (see
+.BR open (2)).
+.TP
+.BR CLONE_FS " (since Linux 2.0)"
+If
+.B CLONE_FS
+is set, the caller and the child process share the same filesystem
+information.
+This includes the root of the filesystem, the current
+working directory, and the umask.
+Any call to
+.BR chroot (2),
+.BR chdir (2),
+or
+.BR umask (2)
+performed by the calling process or the child process also affects the
+other process.
+.IP
+If
+.B CLONE_FS
+is not set, the child process works on a copy of the filesystem
+information of the calling process at the time of the clone call.
+Calls to
+.BR chroot (2),
+.BR chdir (2),
+or
+.BR umask (2)
+performed later by one of the processes do not affect the other process.
+.TP
+.BR CLONE_INTO_CGROUP " (since Linux 5.7)"
+.\" commit ef2c41cf38a7559bbf91af42d5b6a4429db8fc68
+By default, a child process is placed in the same version 2
+cgroup as its parent.
+The
+.B CLONE_INTO_CGROUP
+flag allows the child process to be created in a different version 2 cgroup.
+(Note that
+.B CLONE_INTO_CGROUP
+has effect only for version 2 cgroups.)
+.IP
+In order to place the child process in a different cgroup,
+the caller specifies
+.B CLONE_INTO_CGROUP
+in
+.I cl_args.flags
+and passes a file descriptor that refers to a version 2 cgroup in the
+.I cl_args.cgroup
+field.
+(This file descriptor can be obtained by opening a cgroup v2 directory
+using either the
+.B O_RDONLY
+or the
+.B O_PATH
+flag.)
+Note that all of the usual restrictions (described in
+.BR cgroups (7))
+on placing a process into a version 2 cgroup apply.
+.IP
+Among the possible use cases for
+.B CLONE_INTO_CGROUP
+are the following:
+.RS
+.IP \[bu] 3
+Spawning a process into a cgroup different from the parent's cgroup
+makes it possible for a service manager to directly spawn new
+services into dedicated cgroups.
+This eliminates the accounting
+jitter that would be caused if the child process was first created in the
+same cgroup as the parent and then
+moved into the target cgroup.
+Furthermore, spawning the child process directly into a target cgroup
+is significantly cheaper than moving the child process into
+the target cgroup after it has been created.
+.IP \[bu]
+The
+.B CLONE_INTO_CGROUP
+flag also allows the creation of
+frozen child processes by spawning them into a frozen cgroup.
+(See
+.BR cgroups (7)
+for a description of the freezer controller.)
+.IP \[bu]
+For threaded applications (or even thread implementations which
+make use of cgroups to limit individual threads), it is possible to
+establish a fixed cgroup layout before spawning each thread
+directly into its target cgroup.
+.RE
+.TP
+.BR CLONE_IO " (since Linux 2.6.25)"
+If
+.B CLONE_IO
+is set, then the new process shares an I/O context with
+the calling process.
+If this flag is not set, then (as with
+.BR fork (2))
+the new process has its own I/O context.
+.IP
+.\" The following based on text from Jens Axboe
+The I/O context is the I/O scope of the disk scheduler (i.e.,
+what the I/O scheduler uses to model scheduling of a process's I/O).
+If processes share the same I/O context,
+they are treated as one by the I/O scheduler.
+As a consequence, they get to share disk time.
+For some I/O schedulers,
+.\" the anticipatory and CFQ scheduler
+if two processes share an I/O context,
+they will be allowed to interleave their disk access.
+If several threads are doing I/O on behalf of the same process
+.RB ( aio_read (3),
+for instance), they should employ
+.B CLONE_IO
+to get better I/O performance.
+.\" with CFQ and AS.
+.IP
+If the kernel is not configured with the
+.B CONFIG_BLOCK
+option, this flag is a no-op.
+.TP
+.BR CLONE_NEWCGROUP " (since Linux 4.6)"
+Create the process in a new cgroup namespace.
+If this flag is not set, then (as with
+.BR fork (2))
+the process is created in the same cgroup namespaces as the calling process.
+.IP
+For further information on cgroup namespaces, see
+.BR cgroup_namespaces (7).
+.IP
+Only a privileged process
+.RB ( CAP_SYS_ADMIN )
+can employ
+.BR CLONE_NEWCGROUP .
+.\"
+.TP
+.BR CLONE_NEWIPC " (since Linux 2.6.19)"
+If
+.B CLONE_NEWIPC
+is set, then create the process in a new IPC namespace.
+If this flag is not set, then (as with
+.BR fork (2)),
+the process is created in the same IPC namespace as
+the calling process.
+.IP
+For further information on IPC namespaces, see
+.BR ipc_namespaces (7).
+.IP
+Only a privileged process
+.RB ( CAP_SYS_ADMIN )
+can employ
+.BR CLONE_NEWIPC .
+This flag can't be specified in conjunction with
+.BR CLONE_SYSVSEM .
+.TP
+.BR CLONE_NEWNET " (since Linux 2.6.24)"
+(The implementation of this flag was completed only
+by about Linux 2.6.29.)
+.IP
+If
+.B CLONE_NEWNET
+is set, then create the process in a new network namespace.
+If this flag is not set, then (as with
+.BR fork (2))
+the process is created in the same network namespace as
+the calling process.
+.IP
+For further information on network namespaces, see
+.BR network_namespaces (7).
+.IP
+Only a privileged process
+.RB ( CAP_SYS_ADMIN )
+can employ
+.BR CLONE_NEWNET .
+.TP
+.BR CLONE_NEWNS " (since Linux 2.4.19)"
+If
+.B CLONE_NEWNS
+is set, the cloned child is started in a new mount namespace,
+initialized with a copy of the namespace of the parent.
+If
+.B CLONE_NEWNS
+is not set, the child lives in the same mount
+namespace as the parent.
+.IP
+For further information on mount namespaces, see
+.BR namespaces (7)
+and
+.BR mount_namespaces (7).
+.IP
+Only a privileged process
+.RB ( CAP_SYS_ADMIN )
+can employ
+.BR CLONE_NEWNS .
+It is not permitted to specify both
+.B CLONE_NEWNS
+and
+.B CLONE_FS
+.\" See https://lwn.net/Articles/543273/
+in the same clone call.
+.TP
+.BR CLONE_NEWPID " (since Linux 2.6.24)"
+.\" This explanation draws a lot of details from
+.\" http://lwn.net/Articles/259217/
+.\" Authors: Pavel Emelyanov <xemul@openvz.org>
+.\" and Kir Kolyshkin <kir@openvz.org>
+.\"
+.\" The primary kernel commit is 30e49c263e36341b60b735cbef5ca37912549264
+.\" Author: Pavel Emelyanov <xemul@openvz.org>
+If
+.B CLONE_NEWPID
+is set, then create the process in a new PID namespace.
+If this flag is not set, then (as with
+.BR fork (2))
+the process is created in the same PID namespace as
+the calling process.
+.IP
+For further information on PID namespaces, see
+.BR namespaces (7)
+and
+.BR pid_namespaces (7).
+.IP
+Only a privileged process
+.RB ( CAP_SYS_ADMIN )
+can employ
+.BR CLONE_NEWPID .
+This flag can't be specified in conjunction with
+.BR CLONE_THREAD .
+.TP
+.B CLONE_NEWUSER
+(This flag first became meaningful for
+.BR clone ()
+in Linux 2.6.23,
+the current
+.BR clone ()
+semantics were merged in Linux 3.5,
+and the final pieces to make the user namespaces completely usable were
+merged in Linux 3.8.)
+.IP
+If
+.B CLONE_NEWUSER
+is set, then create the process in a new user namespace.
+If this flag is not set, then (as with
+.BR fork (2))
+the process is created in the same user namespace as the calling process.
+.IP
+For further information on user namespaces, see
+.BR namespaces (7)
+and
+.BR user_namespaces (7).
+.IP
+Before Linux 3.8, use of
+.B CLONE_NEWUSER
+required that the caller have three capabilities:
+.BR CAP_SYS_ADMIN ,
+.BR CAP_SETUID ,
+and
+.BR CAP_SETGID .
+.\" Before Linux 2.6.29, it appears that only CAP_SYS_ADMIN was needed
+Starting with Linux 3.8,
+no privileges are needed to create a user namespace.
+.IP
+This flag can't be specified in conjunction with
+.B CLONE_THREAD
+or
+.BR CLONE_PARENT .
+For security reasons,
+.\" commit e66eded8309ebf679d3d3c1f5820d1f2ca332c71
+.\" https://lwn.net/Articles/543273/
+.\" The fix actually went into Linux 3.9 and into Linux 3.8.3. However, user namespaces
+.\" were, for practical purposes, unusable in earlier Linux 3.8.x because of the
+.\" various filesystems that didn't support userns.
+.B CLONE_NEWUSER
+cannot be specified in conjunction with
+.BR CLONE_FS .
+.TP
+.BR CLONE_NEWUTS " (since Linux 2.6.19)"
+If
+.B CLONE_NEWUTS
+is set, then create the process in a new UTS namespace,
+whose identifiers are initialized by duplicating the identifiers
+from the UTS namespace of the calling process.
+If this flag is not set, then (as with
+.BR fork (2))
+the process is created in the same UTS namespace as
+the calling process.
+.IP
+For further information on UTS namespaces, see
+.BR uts_namespaces (7).
+.IP
+Only a privileged process
+.RB ( CAP_SYS_ADMIN )
+can employ
+.BR CLONE_NEWUTS .
+.TP
+.BR CLONE_PARENT " (since Linux 2.3.12)"
+If
+.B CLONE_PARENT
+is set, then the parent of the new child (as returned by
+.BR getppid (2))
+will be the same as that of the calling process.
+.IP
+If
+.B CLONE_PARENT
+is not set, then (as with
+.BR fork (2))
+the child's parent is the calling process.
+.IP
+Note that it is the parent process, as returned by
+.BR getppid (2),
+which is signaled when the child terminates, so that
+if
+.B CLONE_PARENT
+is set, then the parent of the calling process, rather than the
+calling process itself, is signaled.
+.IP
+The
+.B CLONE_PARENT
+flag can't be used in clone calls by the
+global init process (PID 1 in the initial PID namespace)
+and init processes in other PID namespaces.
+This restriction prevents the creation of multi-rooted process trees
+as well as the creation of unreapable zombies in the initial PID namespace.
+.TP
+.BR CLONE_PARENT_SETTID " (since Linux 2.5.49)"
+Store the child thread ID at the location pointed to by
+.I parent_tid
+.RB ( clone ())
+or
+.I cl_args.parent_tid
+.RB ( clone3 ())
+in the parent's memory.
+(In Linux 2.5.32-2.5.48 there was a flag
+.B CLONE_SETTID
+that did this.)
+The store operation completes before the clone call
+returns control to user space.
+.TP
+.BR CLONE_PID " (Linux 2.0 to Linux 2.5.15)"
+If
+.B CLONE_PID
+is set, the child process is created with the same process ID as
+the calling process.
+This is good for hacking the system, but otherwise
+of not much use.
+From Linux 2.3.21 onward, this flag could be
+specified only by the system boot process (PID 0).
+The flag disappeared completely from the kernel sources in Linux 2.5.16.
+Subsequently, the kernel silently ignored this bit if it was specified in the
+.I flags
+mask.
+Much later, the same bit was recycled for use as the
+.B CLONE_PIDFD
+flag.
+.TP
+.BR CLONE_PIDFD " (since Linux 5.2)"
+.\" commit b3e5838252665ee4cfa76b82bdf1198dca81e5be
+If this flag is specified,
+a PID file descriptor referring to the child process is allocated
+and placed at a specified location in the parent's memory.
+The close-on-exec flag is set on this new file descriptor.
+PID file descriptors can be used for the purposes described in
+.BR pidfd_open (2).
+.RS
+.IP \[bu] 3
+When using
+.BR clone3 (),
+the PID file descriptor is placed at the location pointed to by
+.IR cl_args.pidfd .
+.IP \[bu]
+When using
+.BR clone (),
+the PID file descriptor is placed at the location pointed to by
+.IR parent_tid .
+Since the
+.I parent_tid
+argument is used to return the PID file descriptor,
+.B CLONE_PIDFD
+cannot be used with
+.B CLONE_PARENT_SETTID
+when calling
+.BR clone ().
+.RE
+.IP
+It is currently not possible to use this flag together with
+.B CLONE_THREAD.
+This means that the process identified by the PID file descriptor
+will always be a thread group leader.
+.IP
+If the obsolete
+.B CLONE_DETACHED
+flag is specified alongside
+.B CLONE_PIDFD
+when calling
+.BR clone (),
+an error is returned.
+An error also results if
+.B CLONE_DETACHED
+is specified when calling
+.BR clone3 ().
+This error behavior ensures that the bit corresponding to
+.B CLONE_DETACHED
+can be reused for further PID file descriptor features in the future.
+.TP
+.BR CLONE_PTRACE " (since Linux 2.2)"
+If
+.B CLONE_PTRACE
+is specified, and the calling process is being traced,
+then trace the child also (see
+.BR ptrace (2)).
+.TP
+.BR CLONE_SETTLS " (since Linux 2.5.32)"
+The TLS (Thread Local Storage) descriptor is set to
+.IR tls .
+.IP
+The interpretation of
+.I tls
+and the resulting effect is architecture dependent.
+On x86,
+.I tls
+is interpreted as a
+.I struct user_desc\~*
+(see
+.BR set_thread_area (2)).
+On x86-64 it is the new value to be set for the %fs base register
+(see the
+.B ARCH_SET_FS
+argument to
+.BR arch_prctl (2)).
+On architectures with a dedicated TLS register, it is the new value
+of that register.
+.IP
+Use of this flag requires detailed knowledge and generally it
+should not be used except in libraries implementing threading.
+.TP
+.BR CLONE_SIGHAND " (since Linux 2.0)"
+If
+.B CLONE_SIGHAND
+is set, the calling process and the child process share the same table of
+signal handlers.
+If the calling process or child process calls
+.BR sigaction (2)
+to change the behavior associated with a signal, the behavior is
+changed in the other process as well.
+However, the calling process and child
+processes still have distinct signal masks and sets of pending
+signals.
+So, one of them may block or unblock signals using
+.BR sigprocmask (2)
+without affecting the other process.
+.IP
+If
+.B CLONE_SIGHAND
+is not set, the child process inherits a copy of the signal handlers
+of the calling process at the time of the clone call.
+Calls to
+.BR sigaction (2)
+performed later by one of the processes have no effect on the other
+process.
+.IP
+Since Linux 2.6.0,
+.\" Precisely: Linux 2.6.0-test6
+the
+.I flags
+mask must also include
+.B CLONE_VM
+if
+.B CLONE_SIGHAND
+is specified.
+.TP
+.BR CLONE_STOPPED " (since Linux 2.6.0)"
+.\" Precisely: Linux 2.6.0-test2
+If
+.B CLONE_STOPPED
+is set, then the child is initially stopped (as though it was sent a
+.B SIGSTOP
+signal), and must be resumed by sending it a
+.B SIGCONT
+signal.
+.IP
+This flag was
+.I deprecated
+from Linux 2.6.25 onward,
+and was
+.I removed
+altogether in Linux 2.6.38.
+Since then, the kernel silently ignores it without error.
+.\" glibc 2.8 removed this defn from bits/sched.h
+Starting with Linux 4.6, the same bit was reused for the
+.B CLONE_NEWCGROUP
+flag.
+.TP
+.BR CLONE_SYSVSEM " (since Linux 2.5.10)"
+If
+.B CLONE_SYSVSEM
+is set, then the child and the calling process share
+a single list of System V semaphore adjustment
+.RI ( semadj )
+values (see
+.BR semop (2)).
+In this case, the shared list accumulates
+.I semadj
+values across all processes sharing the list,
+and semaphore adjustments are performed only when the last process
+that is sharing the list terminates (or ceases sharing the list using
+.BR unshare (2)).
+If this flag is not set, then the child has a separate
+.I semadj
+list that is initially empty.
+.TP
+.BR CLONE_THREAD " (since Linux 2.4.0)"
+.\" Precisely: Linux 2.6.0-test8
+If
+.B CLONE_THREAD
+is set, the child is placed in the same thread group as the calling process.
+To make the remainder of the discussion of
+.B CLONE_THREAD
+more readable, the term "thread" is used to refer to the
+processes within a thread group.
+.IP
+Thread groups were a feature added in Linux 2.4 to support the
+POSIX threads notion of a set of threads that share a single PID.
+Internally, this shared PID is the so-called
+thread group identifier (TGID) for the thread group.
+Since Linux 2.4, calls to
+.BR getpid (2)
+return the TGID of the caller.
+.IP
+The threads within a group can be distinguished by their (system-wide)
+unique thread IDs (TID).
+A new thread's TID is available as the function result
+returned to the caller,
+and a thread can obtain
+its own TID using
+.BR gettid (2).
+.IP
+When a clone call is made without specifying
+.BR CLONE_THREAD ,
+then the resulting thread is placed in a new thread group
+whose TGID is the same as the thread's TID.
+This thread is the
+.I leader
+of the new thread group.
+.IP
+A new thread created with
+.B CLONE_THREAD
+has the same parent process as the process that made the clone call
+(i.e., like
+.BR CLONE_PARENT ),
+so that calls to
+.BR getppid (2)
+return the same value for all of the threads in a thread group.
+When a
+.B CLONE_THREAD
+thread terminates, the thread that created it is not sent a
+.B SIGCHLD
+(or other termination) signal;
+nor can the status of such a thread be obtained
+using
+.BR wait (2).
+(The thread is said to be
+.IR detached .)
+.IP
+After all of the threads in a thread group terminate
+the parent process of the thread group is sent a
+.B SIGCHLD
+(or other termination) signal.
+.IP
+If any of the threads in a thread group performs an
+.BR execve (2),
+then all threads other than the thread group leader are terminated,
+and the new program is executed in the thread group leader.
+.IP
+If one of the threads in a thread group creates a child using
+.BR fork (2),
+then any thread in the group can
+.BR wait (2)
+for that child.
+.IP
+Since Linux 2.5.35, the
+.I flags
+mask must also include
+.B CLONE_SIGHAND
+if
+.B CLONE_THREAD
+is specified
+(and note that, since Linux 2.6.0,
+.\" Precisely: Linux 2.6.0-test6
+.B CLONE_SIGHAND
+also requires
+.B CLONE_VM
+to be included).
+.IP
+Signal dispositions and actions are process-wide:
+if an unhandled signal is delivered to a thread, then
+it will affect (terminate, stop, continue, be ignored in)
+all members of the thread group.
+.IP
+Each thread has its own signal mask, as set by
+.BR sigprocmask (2).
+.IP
+A signal may be process-directed or thread-directed.
+A process-directed signal is targeted at a thread group (i.e., a TGID),
+and is delivered to an arbitrarily selected thread from among those
+that are not blocking the signal.
+A signal may be process-directed because it was generated by the kernel
+for reasons other than a hardware exception, or because it was sent using
+.BR kill (2)
+or
+.BR sigqueue (3).
+A thread-directed signal is targeted at (i.e., delivered to)
+a specific thread.
+A signal may be thread directed because it was sent using
+.BR tgkill (2)
+or
+.BR pthread_sigqueue (3),
+or because the thread executed a machine language instruction that triggered
+a hardware exception
+(e.g., invalid memory access triggering
+.B SIGSEGV
+or a floating-point exception triggering
+.BR SIGFPE ).
+.IP
+A call to
+.BR sigpending (2)
+returns a signal set that is the union of the pending process-directed
+signals and the signals that are pending for the calling thread.
+.IP
+If a process-directed signal is delivered to a thread group,
+and the thread group has installed a handler for the signal, then
+the handler is invoked in exactly one, arbitrarily selected
+member of the thread group that has not blocked the signal.
+If multiple threads in a group are waiting to accept the same signal using
+.BR sigwaitinfo (2),
+the kernel will arbitrarily select one of these threads
+to receive the signal.
+.TP
+.BR CLONE_UNTRACED " (since Linux 2.5.46)"
+If
+.B CLONE_UNTRACED
+is specified, then a tracing process cannot force
+.B CLONE_PTRACE
+on this child process.
+.TP
+.BR CLONE_VFORK " (since Linux 2.2)"
+If
+.B CLONE_VFORK
+is set, the execution of the calling process is suspended
+until the child releases its virtual memory
+resources via a call to
+.BR execve (2)
+or
+.BR _exit (2)
+(as with
+.BR vfork (2)).
+.IP
+If
+.B CLONE_VFORK
+is not set, then both the calling process and the child are schedulable
+after the call, and an application should not rely on execution occurring
+in any particular order.
+.TP
+.BR CLONE_VM " (since Linux 2.0)"
+If
+.B CLONE_VM
+is set, the calling process and the child process run in the same memory
+space.
+In particular, memory writes performed by the calling process
+or by the child process are also visible in the other process.
+Moreover, any memory mapping or unmapping performed with
+.BR mmap (2)
+or
+.BR munmap (2)
+by the child or calling process also affects the other process.
+.IP
+If
+.B CLONE_VM
+is not set, the child process runs in a separate copy of the memory
+space of the calling process at the time of the clone call.
+Memory writes or file mappings/unmappings performed by one of the
+processes do not affect the other, as with
+.BR fork (2).
+.IP
+If the
+.B CLONE_VM
+flag is specified and the
+.B CLONE_VFORK
+flag is not specified,
+then any alternate signal stack that was established by
+.BR sigaltstack (2)
+is cleared in the child process.
+.SH RETURN VALUE
+.\" gettid(2) returns current->pid;
+.\" getpid(2) returns current->tgid;
+On success, the thread ID of the child process is returned
+in the caller's thread of execution.
+On failure, \-1 is returned
+in the caller's context, no child process is created, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.BR EACCES " (" clone3 "() only)"
+.B CLONE_INTO_CGROUP
+was specified in
+.IR cl_args.flags ,
+but the restrictions (described in
+.BR cgroups (7))
+on placing the child process into the version 2 cgroup referred to by
+.I cl_args.cgroup
+are not met.
+.TP
+.B EAGAIN
+Too many processes are already running; see
+.BR fork (2).
+.TP
+.BR EBUSY " (" clone3 "() only)"
+.B CLONE_INTO_CGROUP
+was specified in
+.IR cl_args.flags ,
+but the file descriptor specified in
+.I cl_args.cgroup
+refers to a version 2 cgroup in which a domain controller is enabled.
+.TP
+.BR EEXIST " (" clone3 "() only)"
+One (or more) of the PIDs specified in
+.I set_tid
+already exists in the corresponding PID namespace.
+.TP
+.B EINVAL
+Both
+.B CLONE_SIGHAND
+and
+.B CLONE_CLEAR_SIGHAND
+were specified in the
+.I flags
+mask.
+.TP
+.B EINVAL
+.B CLONE_SIGHAND
+was specified in the
+.I flags
+mask, but
+.B CLONE_VM
+was not.
+(Since Linux 2.6.0.)
+.\" Precisely: Linux 2.6.0-test6
+.TP
+.B EINVAL
+.B CLONE_THREAD
+was specified in the
+.I flags
+mask, but
+.B CLONE_SIGHAND
+was not.
+(Since Linux 2.5.35.)
+.\" .TP
+.\" .B EINVAL
+.\" Precisely one of
+.\" .B CLONE_DETACHED
+.\" and
+.\" .B CLONE_THREAD
+.\" was specified.
+.\" (Since Linux 2.6.0-test6.)
+.TP
+.B EINVAL
+.B CLONE_THREAD
+was specified in the
+.I flags
+mask, but the current process previously called
+.BR unshare (2)
+with the
+.B CLONE_NEWPID
+flag or used
+.BR setns (2)
+to reassociate itself with a PID namespace.
+.TP
+.B EINVAL
+.\" commit e66eded8309ebf679d3d3c1f5820d1f2ca332c71
+Both
+.B CLONE_FS
+and
+.B CLONE_NEWNS
+were specified in the
+.I flags
+mask.
+.TP
+.BR EINVAL " (since Linux 3.9)"
+Both
+.B CLONE_NEWUSER
+and
+.B CLONE_FS
+were specified in the
+.I flags
+mask.
+.TP
+.B EINVAL
+Both
+.B CLONE_NEWIPC
+and
+.B CLONE_SYSVSEM
+were specified in the
+.I flags
+mask.
+.TP
+.B EINVAL
+.B CLONE_NEWPID
+and one (or both) of
+.B CLONE_THREAD
+or
+.B CLONE_PARENT
+were specified in the
+.I flags
+mask.
+.TP
+.B EINVAL
+.B CLONE_NEWUSER
+and
+.B CLONE_THREAD
+were specified in the
+.I flags
+mask.
+.TP
+.BR EINVAL " (since Linux 2.6.32)"
+.\" commit 123be07b0b399670a7cc3d82fef0cb4f93ef885c
+.B CLONE_PARENT
+was specified, and the caller is an init process.
+.TP
+.B EINVAL
+Returned by the glibc
+.BR clone ()
+wrapper function when
+.I fn
+or
+.I stack
+is specified as NULL.
+.TP
+.B EINVAL
+.B CLONE_NEWIPC
+was specified in the
+.I flags
+mask,
+but the kernel was not configured with the
+.B CONFIG_SYSVIPC
+and
+.B CONFIG_IPC_NS
+options.
+.TP
+.B EINVAL
+.B CLONE_NEWNET
+was specified in the
+.I flags
+mask,
+but the kernel was not configured with the
+.B CONFIG_NET_NS
+option.
+.TP
+.B EINVAL
+.B CLONE_NEWPID
+was specified in the
+.I flags
+mask,
+but the kernel was not configured with the
+.B CONFIG_PID_NS
+option.
+.TP
+.B EINVAL
+.B CLONE_NEWUSER
+was specified in the
+.I flags
+mask,
+but the kernel was not configured with the
+.B CONFIG_USER_NS
+option.
+.TP
+.B EINVAL
+.B CLONE_NEWUTS
+was specified in the
+.I flags
+mask,
+but the kernel was not configured with the
+.B CONFIG_UTS_NS
+option.
+.TP
+.B EINVAL
+.I stack
+is not aligned to a suitable boundary for this architecture.
+For example, on aarch64,
+.I stack
+must be a multiple of 16.
+.TP
+.BR EINVAL " (" clone3 "() only)"
+.B  CLONE_DETACHED
+was specified in the
+.I flags
+mask.
+.TP
+.BR EINVAL " (" clone "() only)"
+.B CLONE_PIDFD
+was specified together with
+.B CLONE_DETACHED
+in the
+.I flags
+mask.
+.TP
+.B EINVAL
+.B CLONE_PIDFD
+was specified together with
+.B CLONE_THREAD
+in the
+.I flags
+mask.
+.TP
+.BR "EINVAL " "("  clone "() only)"
+.B CLONE_PIDFD
+was specified together with
+.B CLONE_PARENT_SETTID
+in the
+.I flags
+mask.
+.TP
+.BR EINVAL " (" clone3 "() only)"
+.I set_tid_size
+is greater than the number of nested PID namespaces.
+.TP
+.BR EINVAL " (" clone3 "() only)"
+One of the PIDs specified in
+.I set_tid
+was an invalid.
+.TP
+.BR EINVAL " (" clone3 "() only)"
+.\" commit 7f192e3cd316ba58c88dfa26796cf77789dd9872
+.B CLONE_THREAD
+or
+.B CLONE_PARENT
+was specified in the
+.I flags
+mask, but a signal was specified in
+.IR exit_signal .
+.TP
+.BR EINVAL " (AArch64 only, Linux 4.6 and earlier)"
+.I stack
+was not aligned to a 128-bit boundary.
+.TP
+.B ENOMEM
+Cannot allocate sufficient memory to allocate a task structure for the
+child, or to copy those parts of the caller's context that need to be
+copied.
+.TP
+.BR ENOSPC " (since Linux 3.7)"
+.\" commit f2302505775fd13ba93f034206f1e2a587017929
+.B CLONE_NEWPID
+was specified in the
+.I flags
+mask,
+but the limit on the nesting depth of PID namespaces
+would have been exceeded; see
+.BR pid_namespaces (7).
+.TP
+.BR ENOSPC " (since Linux 4.9; beforehand " EUSERS )
+.B CLONE_NEWUSER
+was specified in the
+.I flags
+mask, and the call would cause the limit on the number of
+nested user namespaces to be exceeded.
+See
+.BR user_namespaces (7).
+.IP
+From Linux 3.11 to Linux 4.8, the error diagnosed in this case was
+.BR EUSERS .
+.TP
+.BR ENOSPC " (since Linux 4.9)"
+One of the values in the
+.I flags
+mask specified the creation of a new user namespace,
+but doing so would have caused the limit defined by the corresponding file in
+.I /proc/sys/user
+to be exceeded.
+For further details, see
+.BR namespaces (7).
+.TP
+.BR EOPNOTSUPP " (" clone3 "() only)"
+.B CLONE_INTO_CGROUP
+was specified in
+.IR cl_args.flags ,
+but the file descriptor specified in
+.I cl_args.cgroup
+refers to a version 2 cgroup that is in the
+.I domain invalid
+state.
+.TP
+.B EPERM
+.BR CLONE_NEWCGROUP ,
+.BR CLONE_NEWIPC ,
+.BR CLONE_NEWNET ,
+.BR CLONE_NEWNS ,
+.BR CLONE_NEWPID ,
+or
+.B CLONE_NEWUTS
+was specified by an unprivileged process (process without \fBCAP_SYS_ADMIN\fP).
+.TP
+.B EPERM
+.B CLONE_PID
+was specified by a process other than process 0.
+(This error occurs only on Linux 2.5.15 and earlier.)
+.TP
+.B EPERM
+.B CLONE_NEWUSER
+was specified in the
+.I flags
+mask,
+but either the effective user ID or the effective group ID of the caller
+does not have a mapping in the parent namespace (see
+.BR user_namespaces (7)).
+.TP
+.BR EPERM " (since Linux 3.9)"
+.\" commit 3151527ee007b73a0ebd296010f1c0454a919c7d
+.B CLONE_NEWUSER
+was specified in the
+.I flags
+mask and the caller is in a chroot environment
+.\" FIXME What is the rationale for this restriction?
+(i.e., the caller's root directory does not match the root directory
+of the mount namespace in which it resides).
+.TP
+.BR EPERM " (" clone3 "() only)"
+.I set_tid_size
+was greater than zero, and the caller lacks the
+.B CAP_SYS_ADMIN
+capability in one or more of the user namespaces that own the
+corresponding PID namespaces.
+.TP
+.BR ERESTARTNOINTR " (since Linux 2.6.17)"
+.\" commit 4a2c7a7837da1b91468e50426066d988050e4d56
+System call was interrupted by a signal and will be restarted.
+(This can be seen only during a trace.)
+.TP
+.BR EUSERS " (Linux 3.11 to Linux 4.8)"
+.B CLONE_NEWUSER
+was specified in the
+.I flags
+mask,
+and the limit on the number of nested user namespaces would be exceeded.
+See the discussion of the
+.B ENOSPC
+error above.
+.SH VERSIONS
+The glibc
+.BR clone ()
+wrapper function makes some changes
+in the memory pointed to by
+.I stack
+(changes required to set the stack up correctly for the child)
+.I before
+invoking the
+.BR clone ()
+system call.
+So, in cases where
+.BR clone ()
+is used to recursively create children,
+do not use the buffer employed for the parent's stack
+as the stack of the child.
+.P
+On i386,
+.BR clone ()
+should not be called through vsyscall, but directly through
+.IR "int $0x80" .
+.SS C library/kernel differences
+The raw
+.BR clone ()
+system call corresponds more closely to
+.BR fork (2)
+in that execution in the child continues from the point of the
+call.
+As such, the
+.I fn
+and
+.I arg
+arguments of the
+.BR clone ()
+wrapper function are omitted.
+.P
+In contrast to the glibc wrapper, the raw
+.BR clone ()
+system call accepts NULL as a
+.I stack
+argument (and
+.BR clone3 ()
+likewise allows
+.I cl_args.stack
+to be NULL).
+In this case, the child uses a duplicate of the parent's stack.
+(Copy-on-write semantics ensure that the child gets separate copies
+of stack pages when either process modifies the stack.)
+In this case, for correct operation, the
+.B CLONE_VM
+option should not be specified.
+(If the child
+.I shares
+the parent's memory because of the use of the
+.B CLONE_VM
+flag,
+then no copy-on-write duplication occurs and chaos is likely to result.)
+.P
+The order of the arguments also differs in the raw system call,
+and there are variations in the arguments across architectures,
+as detailed in the following paragraphs.
+.P
+The raw system call interface on x86-64 and some other architectures
+(including sh, tile, and alpha) is:
+.P
+.in +4n
+.EX
+.BI "long clone(unsigned long " flags ", void *" stack ,
+.BI "           int *" parent_tid ", int *" child_tid ,
+.BI "           unsigned long " tls );
+.EE
+.in
+.P
+On x86-32, and several other common architectures
+(including score, ARM, ARM 64, PA-RISC, arc, Power PC, xtensa,
+and MIPS),
+.\" CONFIG_CLONE_BACKWARDS
+the order of the last two arguments is reversed:
+.P
+.in +4n
+.EX
+.BI "long clone(unsigned long " flags ", void *" stack ,
+.BI "          int *" parent_tid ", unsigned long " tls ,
+.BI "          int *" child_tid );
+.EE
+.in
+.P
+On the cris and s390 architectures,
+.\" CONFIG_CLONE_BACKWARDS2
+the order of the first two arguments is reversed:
+.P
+.in +4n
+.EX
+.BI "long clone(void *" stack ", unsigned long " flags ,
+.BI "           int *" parent_tid ", int *" child_tid ,
+.BI "           unsigned long " tls );
+.EE
+.in
+.P
+On the microblaze architecture,
+.\" CONFIG_CLONE_BACKWARDS3
+an additional argument is supplied:
+.P
+.in +4n
+.EX
+.BI "long clone(unsigned long " flags ", void *" stack ,
+.BI "           int " stack_size , "\fR         /* Size of stack */"
+.BI "           int *" parent_tid ", int *" child_tid ,
+.BI "           unsigned long " tls );
+.EE
+.in
+.\"
+.SS blackfin, m68k, and sparc
+.\" Mike Frysinger noted in a 2013 mail:
+.\"     these arches don't define __ARCH_WANT_SYS_CLONE:
+.\"     blackfin ia64 m68k sparc
+The argument-passing conventions on
+blackfin, m68k, and sparc are different from the descriptions above.
+For details, see the kernel (and glibc) source.
+.SS ia64
+On ia64, a different interface is used:
+.P
+.in +4n
+.EX
+.BI "int __clone2(int (*" "fn" ")(void *),"
+.BI "             void *" stack_base ", size_t " stack_size ,
+.BI "             int " flags ", void *" "arg" ", ..."
+.BI "          /* pid_t *" parent_tid ", struct user_desc *" tls ,
+.BI "             pid_t *" child_tid " */ );"
+.EE
+.in
+.P
+The prototype shown above is for the glibc wrapper function;
+for the system call itself,
+the prototype can be described as follows (it is identical to the
+.BR clone ()
+prototype on microblaze):
+.P
+.in +4n
+.EX
+.BI "long clone2(unsigned long " flags ", void *" stack_base ,
+.BI "            int " stack_size , "\fR         /* Size of stack */"
+.BI "            int *" parent_tid ", int *" child_tid ,
+.BI "            unsigned long " tls );
+.EE
+.in
+.P
+.BR __clone2 ()
+operates in the same way as
+.BR clone (),
+except that
+.I stack_base
+points to the lowest address of the child's stack area,
+and
+.I stack_size
+specifies the size of the stack pointed to by
+.IR stack_base .
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR clone3 ()
+Linux 5.3.
+.\" There is no entry for
+.\" .BR clone ()
+.\" in libc5.
+.\" glibc2 provides
+.\" .BR clone ()
+.\" as described in this manual page.
+.SS Linux 2.4 and earlier
+In the Linux 2.4.x series,
+.B CLONE_THREAD
+generally does not make the parent of the new thread the same
+as the parent of the calling process.
+However, from Linux 2.4.7 to Linux 2.4.18 the
+.B CLONE_THREAD
+flag implied the
+.B CLONE_PARENT
+flag (as in Linux 2.6.0 and later).
+.P
+In Linux 2.4 and earlier,
+.BR clone ()
+does not take arguments
+.IR parent_tid ,
+.IR tls ,
+and
+.IR child_tid .
+.SH NOTES
+One use of these system calls
+is to implement threads: multiple flows of control in a program that
+run concurrently in a shared address space.
+.P
+The
+.BR kcmp (2)
+system call can be used to test whether two processes share various
+resources such as a file descriptor table,
+System V semaphore undo operations, or a virtual address space.
+.P
+Handlers registered using
+.BR pthread_atfork (3)
+are not executed during a clone call.
+.SH BUGS
+GNU C library versions 2.3.4 up to and including 2.24
+contained a wrapper function for
+.BR getpid (2)
+that performed caching of PIDs.
+This caching relied on support in the glibc wrapper for
+.BR clone (),
+but limitations in the implementation
+meant that the cache was not up to date in some circumstances.
+In particular,
+if a signal was delivered to the child immediately after the
+.BR clone ()
+call, then a call to
+.BR getpid (2)
+in a handler for the signal could return the PID
+of the calling process ("the parent"),
+if the clone wrapper had not yet had a chance to update the PID
+cache in the child.
+(This discussion ignores the case where the child was created using
+.BR CLONE_THREAD ,
+when
+.BR getpid (2)
+.I should
+return the same value in the child and in the process that called
+.BR clone (),
+since the caller and the child are in the same thread group.
+The stale-cache problem also does not occur if the
+.I flags
+argument includes
+.BR CLONE_VM .)
+To get the truth, it was sometimes necessary to use code such as the following:
+.P
+.in +4n
+.EX
+#include <syscall.h>
+\&
+pid_t mypid;
+\&
+mypid = syscall(SYS_getpid);
+.EE
+.in
+.\" See also the following bug reports
+.\" https://bugzilla.redhat.com/show_bug.cgi?id=417521
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=6910
+.P
+Because of the stale-cache problem, as well as other problems noted in
+.BR getpid (2),
+the PID caching feature was removed in glibc 2.25.
+.SH EXAMPLES
+The following program demonstrates the use of
+.BR clone ()
+to create a child process that executes in a separate UTS namespace.
+The child changes the hostname in its UTS namespace.
+Both parent and child then display the system hostname,
+making it possible to see that the hostname
+differs in the UTS namespaces of the parent and child.
+For an example of the use of this program, see
+.BR setns (2).
+.P
+Within the sample program, we allocate the memory that is to
+be used for the child's stack using
+.BR mmap (2)
+rather than
+.BR malloc (3)
+for the following reasons:
+.IP \[bu] 3
+.BR mmap (2)
+allocates a block of memory that starts on a page
+boundary and is a multiple of the page size.
+This is useful if we want to establish a guard page (a page with protection
+.BR PROT_NONE )
+at the end of the stack using
+.BR mprotect (2).
+.IP \[bu]
+We can specify the
+.B MAP_STACK
+flag to request a mapping that is suitable for a stack.
+For the moment, this flag is a no-op on Linux,
+but it exists and has effect on some other systems,
+so we should include it for portability.
+.SS Program source
+.\" SRC BEGIN (clone.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/utsname.h>
+#include <sys/wait.h>
+#include <unistd.h>
+\&
+static int              /* Start function for cloned child */
+childFunc(void *arg)
+{
+    struct utsname uts;
+\&
+    /* Change hostname in UTS namespace of child. */
+\&
+    if (sethostname(arg, strlen(arg)) == \-1)
+        err(EXIT_FAILURE, "sethostname");
+\&
+    /* Retrieve and display hostname. */
+\&
+    if (uname(&uts) == \-1)
+        err(EXIT_FAILURE, "uname");
+    printf("uts.nodename in child:  %s\en", uts.nodename);
+\&
+    /* Keep the namespace open for a while, by sleeping.
+       This allows some experimentation\-\-for example, another
+       process might join the namespace. */
+\&
+    sleep(200);
+\&
+    return 0;           /* Child terminates now */
+}
+\&
+#define STACK_SIZE (1024 * 1024)    /* Stack size for cloned child */
+\&
+int
+main(int argc, char *argv[])
+{
+    char            *stack;         /* Start of stack buffer */
+    char            *stackTop;      /* End of stack buffer */
+    pid_t           pid;
+    struct utsname  uts;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <child\-hostname>\en", argv[0]);
+        exit(EXIT_SUCCESS);
+    }
+\&
+    /* Allocate memory to be used for the stack of the child. */
+\&
+    stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE,
+                 MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, \-1, 0);
+    if (stack == MAP_FAILED)
+        err(EXIT_FAILURE, "mmap");
+\&
+    stackTop = stack + STACK_SIZE;  /* Assume stack grows downward */
+\&
+    /* Create child that has its own UTS namespace;
+       child commences execution in childFunc(). */
+\&
+    pid = clone(childFunc, stackTop, CLONE_NEWUTS | SIGCHLD, argv[1]);
+    if (pid == \-1)
+        err(EXIT_FAILURE, "clone");
+    printf("clone() returned %jd\en", (intmax_t) pid);
+\&
+    /* Parent falls through to here */
+\&
+    sleep(1);           /* Give child time to change its hostname */
+\&
+    /* Display hostname in parent\[aq]s UTS namespace. This will be
+       different from hostname in child\[aq]s UTS namespace. */
+\&
+    if (uname(&uts) == \-1)
+        err(EXIT_FAILURE, "uname");
+    printf("uts.nodename in parent: %s\en", uts.nodename);
+\&
+    if (waitpid(pid, NULL, 0) == \-1)    /* Wait for child */
+        err(EXIT_FAILURE, "waitpid");
+    printf("child has terminated\en");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fork (2),
+.BR futex (2),
+.BR getpid (2),
+.BR gettid (2),
+.BR kcmp (2),
+.BR mmap (2),
+.BR pidfd_open (2),
+.BR set_thread_area (2),
+.BR set_tid_address (2),
+.BR setns (2),
+.BR tkill (2),
+.BR unshare (2),
+.BR wait (2),
+.BR capabilities (7),
+.BR namespaces (7),
+.BR pthreads (7)
diff --git a/man/man2/clone2.2 b/man/man2/clone2.2
new file mode 100644
index 000000000..68f41a5ba
--- /dev/null
+++ b/man/man2/clone2.2
@@ -0,0 +1 @@
+.so man2/clone.2
diff --git a/man/man2/clone3.2 b/man/man2/clone3.2
new file mode 100644
index 000000000..68f41a5ba
--- /dev/null
+++ b/man/man2/clone3.2
@@ -0,0 +1 @@
+.so man2/clone.2
diff --git a/man/man2/close.2 b/man/man2/close.2
new file mode 100644
index 000000000..cc6d2f43e
--- /dev/null
+++ b/man/man2/close.2
@@ -0,0 +1,274 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\" and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 21 22:40:25 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sat Feb 18 15:27:48 1995 by Michael Haardt
+.\" Modified Sun Apr 14 11:40:50 1996 by Andries Brouwer <aeb@cwi.nl>:
+.\"   corrected description of effect on locks (thanks to
+.\"   Tigran Aivazian <tigran@sco.com>).
+.\" Modified Fri Jan 31 16:21:46 1997 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2000-07-22 by Nicolás Lichtmaier <nick@debian.org>
+.\"   added note about close(2) not guaranteeing that data is safe on close.
+.\"
+.TH close 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+close \- close a file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int close(int " fd );
+.fi
+.SH DESCRIPTION
+.BR close ()
+closes a file descriptor, so that it no longer refers to any file and
+may be reused.
+Any record locks (see
+.BR fcntl (2))
+held on the file it was associated with,
+and owned by the process,
+are removed regardless of the file descriptor that was used to obtain the lock.
+This has some unfortunate consequences
+and one should be extra careful when using advisory record locking.
+See
+.BR fcntl (2)
+for discussion of the risks and consequences
+as well as for the (probably preferred) open file description locks.
+.P
+If
+.I fd
+is the last file descriptor referring to the underlying
+open file description (see
+.BR open (2)),
+the resources associated with the open file description are freed;
+if the file descriptor was the last reference to a file which has been
+removed using
+.BR unlink (2),
+the file is deleted.
+.SH RETURN VALUE
+.BR close ()
+returns zero on success.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+isn't a valid open file descriptor.
+.TP
+.B EINTR
+.\" Though, it's in doubt whether this error can ever occur; see
+.\" https://lwn.net/Articles/576478/ "Returning EINTR from close()"
+The
+.BR close ()
+call was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B ENOSPC
+.TQ
+.B EDQUOT
+On NFS, these errors are not normally reported against the first write
+which exceeds the available storage space, but instead against a
+subsequent
+.BR write (2),
+.BR fsync (2),
+or
+.BR close ().
+.P
+See NOTES for a discussion of why
+.BR close ()
+should not be retried after an error.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.\" SVr4 documents an additional ENOLINK error condition.
+.SH NOTES
+A successful close does not guarantee that the data has been successfully
+saved to disk, as the kernel uses the buffer cache to defer writes.
+Typically, filesystems do not flush buffers when a file is closed.
+If you need to be sure that
+the data is physically stored on the underlying disk, use
+.BR fsync (2).
+(It will depend on the disk hardware at this point.)
+.P
+The close-on-exec file descriptor flag can be used to ensure
+that a file descriptor is automatically closed upon a successful
+.BR execve (2);
+see
+.BR fcntl (2)
+for details.
+.\"
+.SS Multithreaded processes and close()
+It is probably unwise to close file descriptors while
+they may be in use by system calls in
+other threads in the same process.
+Since a file descriptor may be reused,
+there are some obscure race conditions
+that may cause unintended side effects.
+.\" Date: Tue, 4 Sep 2007 13:57:35 +0200
+.\" From: Fredrik Noring <noring@nocrew.org>
+.\" One such race involves signals and ERESTARTSYS. If a file descriptor
+.\" in use by a system call is closed and then reused by e.g. an
+.\" independent open() in some unrelated thread, before the original system
+.\" call has restarted after ERESTARTSYS, the original system call will
+.\" later restart with the reused file descriptor. This is most likely a
+.\" serious programming error.
+.P
+Furthermore, consider the following scenario where two threads are
+performing operations on the same file descriptor:
+.IP (1) 5
+One thread is blocked in an I/O system call on the file descriptor.
+For example, it is trying to
+.BR write (2)
+to a pipe that is already full, or trying to
+.BR read (2)
+from a stream socket which currently has no available data.
+.IP (2)
+Another thread closes the file descriptor.
+.P
+The behavior in this situation varies across systems.
+On some systems, when the file descriptor is closed,
+the blocking system call returns immediately with an error.
+.P
+On Linux (and possibly some other systems), the behavior is different:
+the blocking I/O system call holds a reference to the underlying
+open file description, and this reference keeps the description open
+until the I/O system call completes.
+.\" 'struct file' in kernel-speak
+(See
+.BR open (2)
+for a discussion of open file descriptions.)
+Thus, the blocking system call in the first thread may successfully
+complete after the
+.BR close ()
+in the second thread.
+.\"
+.SS Dealing with error returns from close()
+A careful programmer will check the return value of
+.BR close (),
+since it is quite possible that errors on a previous
+.BR write (2)
+operation are reported only on the final
+.BR close ()
+that releases the open file description.
+Failing to check the return value when closing a file may lead to
+.I silent
+loss of data.
+This can especially be observed with NFS and with disk quota.
+.P
+Note, however, that a failure return should be used only for
+diagnostic purposes (i.e., a warning to the application that there
+may still be I/O pending or there may have been failed I/O)
+or remedial purposes
+(e.g., writing the file once more or creating a backup).
+.P
+Retrying the
+.BR close ()
+after a failure return is the wrong thing to do,
+.\" The file descriptor is released early in close();
+.\" close() ==> __close_fd():
+.\"			__put_unused_fd() ==> __clear_open_fd()
+.\"			return filp_close(file, files);
+.\"
+.\" The errors are returned by filp_close() after the FD has been
+.\" cleared for re-use.
+since this may cause a reused file descriptor
+from another thread to be closed.
+This can occur because the Linux kernel
+.I always
+releases the file descriptor early in the close
+operation, freeing it for reuse;
+the steps that may return an error,
+.\" filp_close()
+such as flushing data to the filesystem or device,
+occur only later in the close operation.
+.P
+Many other implementations similarly always close the file descriptor
+.\" FreeBSD documents this explicitly. From the look of the source code
+.\" SVR4, ancient SunOS, later Solaris, and AIX all do this.
+(except in the case of
+.BR EBADF ,
+meaning that the file descriptor was invalid)
+even if they subsequently report an error on return from
+.BR close ().
+POSIX.1 is currently silent on this point,
+but there are plans to mandate this behavior in the next major release
+.\" Issue 8
+of the standard.
+.P
+A careful programmer who wants to know about I/O errors may precede
+.BR close ()
+with a call to
+.BR fsync (2).
+.P
+The
+.B EINTR
+error is a somewhat special case.
+Regarding the
+.B EINTR
+error, POSIX.1-2008 says:
+.P
+.RS
+If
+.BR close ()
+is interrupted by a signal that is to be caught, it shall return \-1 with
+.I errno
+set to
+.B EINTR
+and the state of
+.I fildes
+is unspecified.
+.RE
+.P
+This permits the behavior that occurs on Linux and
+many other implementations, where,
+as with other errors that may be reported by
+.BR close (),
+the file descriptor is guaranteed to be closed.
+However, it also permits another possibility:
+that the implementation returns an
+.B EINTR
+error and keeps the file descriptor open.
+(According to its documentation, HP-UX's
+.BR close ()
+does this.)
+The caller must then once more use
+.BR close ()
+to close the file descriptor, to avoid file descriptor leaks.
+This divergence in implementation behaviors provides
+a difficult hurdle for portable applications, since on many implementations,
+.BR close ()
+must not be called again after an
+.B EINTR
+error, and on at least one,
+.BR close ()
+must be called again.
+There are plans to address this conundrum for
+the next major release of the POSIX.1 standard.
+.\" FIXME . for later review when Issue 8 is one day released...
+.\" POSIX proposes further changes for EINTR
+.\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
+.\" http://austingroupbugs.net/view.php?id=529
+.\"
+.\" FIXME .
+.\" Review the following glibc bug later
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=14627
+.SH SEE ALSO
+.BR close_range (2),
+.BR fcntl (2),
+.BR fsync (2),
+.BR open (2),
+.BR shutdown (2),
+.BR unlink (2),
+.BR fclose (3)
diff --git a/man/man2/close_range.2 b/man/man2/close_range.2
new file mode 100644
index 000000000..c5252d660
--- /dev/null
+++ b/man/man2/close_range.2
@@ -0,0 +1,276 @@
+.\" Copyright (c) 2020 Stephen Kitt <steve@sk2.org>
+.\" and Copyright (c) 2021 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH close_range 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+close_range \- close all file descriptors in a given range
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BR "#include <linux/close_range.h>" " /* Definition of " CLOSE_RANGE_*
+.BR "" "                                  constants */"
+.P
+.BI "int close_range(unsigned int " first ", unsigned int " last \
+", int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR close_range ()
+system call closes all open file descriptors from
+.I first
+to
+.I last
+(included).
+.P
+Errors closing a given file descriptor are currently ignored.
+.P
+.I flags
+is a bit mask containing 0 or more of the following:
+.TP
+.BR CLOSE_RANGE_CLOEXEC " (since Linux 5.11)"
+Set the close-on-exec flag on the specified file descriptors,
+rather than immediately closing them.
+.TP
+.B CLOSE_RANGE_UNSHARE
+Unshare the specified file descriptors from any other processes
+before closing them,
+avoiding races with other threads sharing the file descriptor table.
+.SH RETURN VALUE
+On success,
+.BR close_range ()
+returns 0.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I flags
+is not valid, or
+.I first
+is greater than
+.IR last .
+.P
+The following can occur with
+.B CLOSE_RANGE_UNSHARE
+(when constructing the new descriptor table):
+.TP
+.B EMFILE
+The number of open file descriptors exceeds the limit specified in
+.I /proc/sys/fs/nr_open
+(see
+.BR proc (5)).
+This error can occur in situations where that limit was lowered before
+a call to
+.BR close_range ()
+where the
+.B CLOSE_RANGE_UNSHARE
+flag is specified.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.SH STANDARDS
+None.
+.SH HISTORY
+FreeBSD.
+Linux 5.9,
+glibc 2.34.
+.SH NOTES
+.SS Closing all open file descriptors
+.\" 278a5fbaed89dacd04e9d052f4594ffd0e0585de
+To avoid blindly closing file descriptors
+in the range of possible file descriptors,
+this is sometimes implemented (on Linux)
+by listing open file descriptors in
+.I /proc/self/fd/
+and calling
+.BR close (2)
+on each one.
+.BR close_range ()
+can take care of this without requiring
+.I /proc
+and within a single system call,
+which provides significant performance benefits.
+.SS Closing file descriptors before exec
+.\" 60997c3d45d9a67daf01c56d805ae4fec37e0bd8
+File descriptors can be closed safely using
+.P
+.in +4n
+.EX
+/* we don't want anything past stderr here */
+close_range(3, \[ti]0U, CLOSE_RANGE_UNSHARE);
+execve(....);
+.EE
+.in
+.P
+.B CLOSE_RANGE_UNSHARE
+is conceptually equivalent to
+.P
+.in +4n
+.EX
+unshare(CLONE_FILES);
+close_range(first, last, 0);
+.EE
+.in
+.P
+but can be more efficient:
+if the unshared range extends past
+the current maximum number of file descriptors allocated
+in the caller's file descriptor table
+(the common case when
+.I last
+is \[ti]0U),
+the kernel will unshare a new file descriptor table for the caller up to
+.IR first ,
+copying as few file descriptors as possible.
+This avoids subsequent
+.BR close (2)
+calls entirely;
+the whole operation is complete once the table is unshared.
+.SS Closing files on \fBexec\fP
+.\" 582f1fb6b721facf04848d2ca57f34468da1813e
+This is particularly useful in cases where multiple
+.RB pre- exec
+setup steps risk conflicting with each other.
+For example, setting up a
+.BR seccomp (2)
+profile can conflict with a
+.BR close_range ()
+call:
+if the file descriptors are closed before the
+.BR seccomp (2)
+profile is set up,
+the profile setup can't use them itself,
+or control their closure;
+if the file descriptors are closed afterwards,
+the seccomp profile can't block the
+.BR close_range ()
+call or any fallbacks.
+Using
+.B CLOSE_RANGE_CLOEXEC
+avoids this:
+the descriptors can be marked before the
+.BR seccomp (2)
+profile is set up,
+and the profile can control access to
+.BR close_range ()
+without affecting the calling process.
+.SH EXAMPLES
+The program shown below opens the files named in its command-line arguments,
+displays the list of files that it has opened
+(by iterating through the entries in
+.IR /proc/PID/fd ),
+uses
+.BR close_range ()
+to close all file descriptors greater than or equal to 3,
+and then once more displays the process's list of open files.
+The following example demonstrates the use of the program:
+.P
+.in +4n
+.EX
+$ \fBtouch /tmp/a /tmp/b /tmp/c\fP
+$ \fB./a.out /tmp/a /tmp/b /tmp/c\fP
+/tmp/a opened as FD 3
+/tmp/b opened as FD 4
+/tmp/c opened as FD 5
+/proc/self/fd/0 ==> /dev/pts/1
+/proc/self/fd/1 ==> /dev/pts/1
+/proc/self/fd/2 ==> /dev/pts/1
+/proc/self/fd/3 ==> /tmp/a
+/proc/self/fd/4 ==> /tmp/b
+/proc/self/fd/5 ==> /tmp/b
+/proc/self/fd/6 ==> /proc/9005/fd
+========= About to call close_range() =======
+/proc/self/fd/0 ==> /dev/pts/1
+/proc/self/fd/1 ==> /dev/pts/1
+/proc/self/fd/2 ==> /dev/pts/1
+/proc/self/fd/3 ==> /proc/9005/fd
+.EE
+.in
+.P
+Note that the lines showing the pathname
+.I /proc/9005/fd
+result from the calls to
+.BR opendir (3).
+.SS Program source
+\&
+.\" SRC BEGIN (close_range.c)
+.EX
+#define _GNU_SOURCE
+#include <dirent.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+/* Show the contents of the symbolic links in /proc/self/fd */
+\&
+static void
+show_fds(void)
+{
+    DIR            *dirp;
+    char           path[PATH_MAX], target[PATH_MAX];
+    ssize_t        len;
+    struct dirent  *dp;
+\&
+    dirp = opendir("/proc/self/fd");
+    if (dirp  == NULL) {
+        perror("opendir");
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (;;) {
+        dp = readdir(dirp);
+        if (dp == NULL)
+            break;
+\&
+        if (dp\->d_type == DT_LNK) {
+            snprintf(path, sizeof(path), "/proc/self/fd/%s",
+                     dp\->d_name);
+\&
+            len = readlink(path, target, sizeof(target));
+            printf("%s ==> %.*s\en", path, (int) len, target);
+        }
+    }
+\&
+    closedir(dirp);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int  fd;
+\&
+    for (size_t j = 1; j < argc; j++) {
+        fd = open(argv[j], O_RDONLY);
+        if (fd == \-1) {
+            perror(argv[j]);
+            exit(EXIT_FAILURE);
+        }
+        printf("%s opened as FD %d\en", argv[j], fd);
+    }
+\&
+    show_fds();
+\&
+    printf("========= About to call close_range() =======\en");
+\&
+    if (close_range(3, \[ti]0U, 0) == \-1) {
+        perror("close_range");
+        exit(EXIT_FAILURE);
+    }
+\&
+    show_fds();
+    exit(EXIT_FAILURE);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR close (2)
diff --git a/man/man2/connect.2 b/man/man2/connect.2
new file mode 100644
index 000000000..dc4d51c59
--- /dev/null
+++ b/man/man2/connect.2
@@ -0,0 +1,253 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\" Portions extracted from /usr/include/sys/socket.h, which does not have
+.\" any authorship information in it.  It is probably available under the GPL.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.\" Other portions are from the 6.9 (Berkeley) 3/10/91 man page:
+.\"
+.\" Copyright (c) 1983 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998, 1999 by Andi Kleen
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH connect 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+connect \- initiate a connection on a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int connect(int " sockfd ", const struct sockaddr *" addr ,
+.BI "            socklen_t " addrlen );
+.fi
+.SH DESCRIPTION
+The
+.BR connect ()
+system call connects the socket referred to by the file descriptor
+.I sockfd
+to the address specified by
+.IR addr .
+The
+.I addrlen
+argument specifies the size of
+.IR addr .
+The format of the address in
+.I addr
+is determined by the address space of the socket
+.IR sockfd ;
+see
+.BR socket (2)
+for further details.
+.P
+If the socket
+.I sockfd
+is of type
+.BR SOCK_DGRAM ,
+then
+.I addr
+is the address to which datagrams are sent by default, and the only
+address from which datagrams are received.
+If the socket is of type
+.B SOCK_STREAM
+or
+.BR SOCK_SEQPACKET ,
+this call attempts to make a connection to the socket that is bound
+to the address specified by
+.IR addr .
+.P
+Some protocol sockets (e.g., UNIX domain stream sockets)
+may successfully
+.BR connect ()
+only once.
+.P
+Some protocol sockets
+(e.g., datagram sockets in the UNIX and Internet domains)
+may use
+.BR connect ()
+multiple times to change their association.
+.P
+Some protocol sockets
+(e.g., TCP sockets as well as datagram sockets in the UNIX and
+Internet domains)
+may dissolve the association by connecting to an address with the
+.I sa_family
+member of
+.I sockaddr
+set to
+.BR AF_UNSPEC ;
+thereafter, the socket can be connected to another address.
+.RB ( AF_UNSPEC
+is supported since Linux 2.2.)
+.SH RETURN VALUE
+If the connection or binding succeeds, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The following are general socket errors only.
+There may be other domain-specific error codes.
+.TP
+.B EACCES
+For UNIX domain sockets, which are identified by pathname:
+Write permission is denied on the socket file,
+or search permission is denied for one of the directories
+in the path prefix.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EACCES
+.TQ
+.B EPERM
+The user tried to connect to a broadcast address without having the socket
+broadcast flag enabled or the connection request failed because of a local
+firewall rule.
+.TP
+.B EACCES
+It can also be returned if an SELinux policy denied a connection (for
+example, if there is a policy saying that an HTTP proxy can only
+connect to ports associated with HTTP servers, and the proxy tries to
+connect to a different port).
+.TP
+.B EADDRINUSE
+Local address is already in use.
+.TP
+.B EADDRNOTAVAIL
+(Internet domain sockets)
+The socket referred to by
+.I sockfd
+had not previously been bound to an address and,
+upon attempting to bind it to an ephemeral port,
+it was determined that all port numbers in the ephemeral port range
+are currently in use.
+See the discussion of
+.I /proc/sys/net/ipv4/ip_local_port_range
+in
+.BR ip (7).
+.TP
+.B EAFNOSUPPORT
+The passed address didn't have the correct address family in its
+.I sa_family
+field.
+.TP
+.B EAGAIN
+For nonblocking UNIX domain sockets, the socket is nonblocking, and the
+connection cannot be completed immediately.
+For other socket families, there are insufficient entries in the routing cache.
+.TP
+.B EALREADY
+The socket is nonblocking and a previous connection attempt has not yet
+been completed.
+.TP
+.B EBADF
+.I sockfd
+is not a valid open file descriptor.
+.TP
+.B ECONNREFUSED
+A
+.BR connect ()
+on a stream socket found no one listening on the remote address.
+.TP
+.B EFAULT
+The socket structure address is outside the user's address space.
+.TP
+.B EINPROGRESS
+The socket is nonblocking and the connection cannot be completed immediately.
+(UNIX domain sockets failed with
+.B EAGAIN
+instead.)
+It is possible to
+.BR select (2)
+or
+.BR poll (2)
+for completion by selecting the socket for writing.
+After
+.BR select (2)
+indicates writability, use
+.BR getsockopt (2)
+to read the
+.B SO_ERROR
+option at level
+.B SOL_SOCKET
+to determine whether
+.BR connect ()
+completed successfully
+.RB ( SO_ERROR
+is zero) or unsuccessfully
+.RB ( SO_ERROR
+is one of the usual error codes listed here,
+explaining the reason for the failure).
+.TP
+.B EINTR
+The system call was interrupted by a signal that was caught; see
+.BR signal (7).
+.\" For TCP, the connection will complete asynchronously.
+.\" See http://lkml.org/lkml/2005/7/12/254
+.TP
+.B EISCONN
+The socket is already connected.
+.TP
+.B ENETUNREACH
+Network is unreachable.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.TP
+.B EPROTOTYPE
+The socket type does not support the requested communications protocol.
+This error can occur, for example,
+on an attempt to connect a UNIX domain datagram socket to a stream socket.
+.TP
+.B ETIMEDOUT
+Timeout while attempting connection.
+The server may be too
+busy to accept new connections.
+Note that for IP sockets the timeout may
+be very long when syncookies are enabled on the server.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD,
+.RB ( connect ()
+first appeared in 4.2BSD).
+.\" SVr4 documents the additional
+.\" general error codes
+.\" .BR EADDRNOTAVAIL ,
+.\" .BR EINVAL ,
+.\" .BR EAFNOSUPPORT ,
+.\" .BR EALREADY ,
+.\" .BR EINTR ,
+.\" .BR EPROTOTYPE ,
+.\" and
+.\" .BR ENOSR .
+.\" It also
+.\" documents many additional error conditions not described here.
+.SH NOTES
+If
+.BR connect ()
+fails, consider the state of the socket as unspecified.
+Portable applications should close the socket and create a new one for
+reconnecting.
+.SH EXAMPLES
+An example of the use of
+.BR connect ()
+is shown in
+.BR getaddrinfo (3).
+.SH SEE ALSO
+.BR accept (2),
+.BR bind (2),
+.BR getsockname (2),
+.BR listen (2),
+.BR socket (2),
+.BR path_resolution (7),
+.BR selinux (8)
diff --git a/man/man2/copy_file_range.2 b/man/man2/copy_file_range.2
new file mode 100644
index 000000000..913d94345
--- /dev/null
+++ b/man/man2/copy_file_range.2
@@ -0,0 +1,307 @@
+.\"This manpage is Copyright (C) 2015 Anna Schumaker <Anna.Schumaker@Netapp.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH copy_file_range 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+copy_file_range \- Copy a range of data from one file to another
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #define _GNU_SOURCE
+.B #define _FILE_OFFSET_BITS 64
+.B #include <unistd.h>
+.P
+.BI "ssize_t copy_file_range(int " fd_in ", off_t *_Nullable " off_in ,
+.BI "                        int " fd_out ", off_t *_Nullable " off_out ,
+.BI "                        size_t " len ", unsigned int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR copy_file_range ()
+system call performs an in-kernel copy between two file descriptors
+without the additional cost of transferring data from the kernel to user space
+and then back into the kernel.
+It copies up to
+.I len
+bytes of data from the source file descriptor
+.I fd_in
+to the target file descriptor
+.IR fd_out ,
+overwriting any data that exists within the requested range of the target file.
+.P
+The following semantics apply for
+.IR off_in ,
+and similar statements apply to
+.IR off_out :
+.IP \[bu] 3
+If
+.I off_in
+is NULL, then bytes are read from
+.I fd_in
+starting from the file offset, and the file offset is
+adjusted by the number of bytes copied.
+.IP \[bu]
+If
+.I off_in
+is not NULL, then
+.I off_in
+must point to a buffer that specifies the starting
+offset where bytes from
+.I fd_in
+will be read.
+The file offset of
+.I fd_in
+is not changed, but
+.I off_in
+is adjusted appropriately.
+.P
+.I fd_in
+and
+.I fd_out
+can refer to the same file.
+If they refer to the same file, then the source and target ranges are not
+allowed to overlap.
+.P
+The
+.I flags
+argument is provided to allow for future extensions
+and currently must be set to 0.
+.SH RETURN VALUE
+Upon successful completion,
+.BR copy_file_range ()
+will return the number of bytes copied between files.
+This could be less than the length originally requested.
+If the file offset of
+.I fd_in
+is at or past the end of file, no bytes are copied, and
+.BR copy_file_range ()
+returns zero.
+.P
+On error,
+.BR copy_file_range ()
+returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+One or more file descriptors are not valid.
+.TP
+.B EBADF
+.I fd_in
+is not open for reading; or
+.I fd_out
+is not open for writing.
+.TP
+.B EBADF
+The
+.B O_APPEND
+flag is set for the open file description (see
+.BR open (2))
+referred to by the file descriptor
+.IR fd_out .
+.TP
+.B EFBIG
+An attempt was made to write at a position past the maximum file offset the
+kernel supports.
+.TP
+.B EFBIG
+An attempt was made to write a range that exceeds the allowed maximum file size.
+The maximum file size differs between filesystem implementations and can be
+different from the maximum allowed file offset.
+.TP
+.B EFBIG
+An attempt was made to write beyond the process's file size resource limit.
+This may also result in the process receiving a
+.B SIGXFSZ
+signal.
+.TP
+.B EINVAL
+The
+.I flags
+argument is not 0.
+.TP
+.B EINVAL
+.I fd_in
+and
+.I fd_out
+refer to the same file and the source and target ranges overlap.
+.TP
+.B EINVAL
+Either
+.I fd_in
+or
+.I fd_out
+is not a regular file.
+.TP
+.B EIO
+A low-level I/O error occurred while copying.
+.TP
+.B EISDIR
+Either
+.I fd_in
+or
+.I fd_out
+refers to a directory.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ENOSPC
+There is not enough space on the target filesystem to complete the copy.
+.TP
+.BR EOPNOTSUPP " (since Linux 5.19)"
+.\" commit 868f9f2f8e004bfe0d3935b1976f625b2924893b
+The filesystem does not support this operation.
+.TP
+.B EOVERFLOW
+The requested source or destination range is too large to represent in the
+specified data types.
+.TP
+.B EPERM
+.I fd_out
+refers to an immutable file.
+.TP
+.B ETXTBSY
+Either
+.I fd_in
+or
+.I fd_out
+refers to an active swap file.
+.TP
+.BR EXDEV " (before Linux 5.3)"
+.\" commit 5dae222a5ff0c269730393018a5539cc970a4726
+The files referred to by
+.IR fd_in " and " fd_out
+are not on the same filesystem.
+.TP
+.BR EXDEV " (since Linux 5.19)"
+.\" commit 868f9f2f8e004bfe0d3935b1976f625b2924893b
+The files referred to by
+.IR fd_in " and " fd_out
+are not on the same filesystem,
+and the source and target filesystems are not of the same type,
+or do not support cross-filesystem copy.
+.SH VERSIONS
+A major rework of the kernel implementation occurred in Linux 5.3.
+Areas of the API that weren't clearly defined were clarified and the API bounds
+are much more strictly checked than on earlier kernels.
+.P
+Since Linux 5.19,
+cross-filesystem copies can be achieved
+when both filesystems are of the same type,
+and that filesystem implements support for it.
+See BUGS for behavior prior to Linux 5.19.
+.P
+Applications should target the behaviour and requirements of Linux 5.19,
+that was also backported to earlier stable kernels.
+.SH STANDARDS
+Linux, GNU.
+.SH HISTORY
+Linux 4.5,
+but glibc 2.27 provides a user-space
+emulation when it is not available.
+.\" https://sourceware.org/git/?p=glibc.git;a=commit;f=posix/unistd.h;h=bad7a0c81f501fbbcc79af9eaa4b8254441c4a1f
+.SH NOTES
+If
+.I fd_in
+is a sparse file, then
+.BR copy_file_range ()
+may expand any holes existing in the requested range.
+Users may benefit from calling
+.BR copy_file_range ()
+in a loop, and using the
+.BR lseek (2)
+.B SEEK_DATA
+and
+.B SEEK_HOLE
+operations to find the locations of data segments.
+.P
+.BR copy_file_range ()
+gives filesystems an opportunity to implement "copy acceleration" techniques,
+such as the use of reflinks (i.e., two or more inodes that share
+pointers to the same copy-on-write disk blocks)
+or server-side-copy (in the case of NFS).
+.P
+.B _FILE_OFFSET_BITS
+should be defined to be 64 in code that uses non-null
+.I off_in
+or
+.I off_out
+or that takes the address of
+.BR copy_file_range ,
+if the code is intended to be portable
+to traditional 32-bit x86 and ARM platforms where
+.BR off_t 's
+width defaults to 32 bits.
+.SH BUGS
+In Linux 5.3 to Linux 5.18,
+cross-filesystem copies were implemented by the kernel,
+if the operation was not supported by individual filesystems.
+However, on some virtual filesystems,
+the call failed to copy, while still reporting success.
+.SH EXAMPLES
+.\" SRC BEGIN (copy_file_range.c)
+.EX
+#define _GNU_SOURCE
+#define _FILE_OFFSET_BITS 64
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int          fd_in, fd_out;
+    off_t        len, ret;
+    struct stat  stat;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <source> <destination>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fd_in = open(argv[1], O_RDONLY);
+    if (fd_in == \-1) {
+        perror("open (argv[1])");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (fstat(fd_in, &stat) == \-1) {
+        perror("fstat");
+        exit(EXIT_FAILURE);
+    }
+\&
+    len = stat.st_size;
+\&
+    fd_out = open(argv[2], O_CREAT | O_WRONLY | O_TRUNC, 0644);
+    if (fd_out == \-1) {
+        perror("open (argv[2])");
+        exit(EXIT_FAILURE);
+    }
+\&
+    do {
+        ret = copy_file_range(fd_in, NULL, fd_out, NULL, len, 0);
+        if (ret == \-1) {
+            perror("copy_file_range");
+            exit(EXIT_FAILURE);
+        }
+\&
+        len \-= ret;
+    } while (len > 0 && ret > 0);
+\&
+    close(fd_in);
+    close(fd_out);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR lseek (2),
+.BR sendfile (2),
+.BR splice (2)
diff --git a/man/man2/creat.2 b/man/man2/creat.2
new file mode 100644
index 000000000..604e1213a
--- /dev/null
+++ b/man/man2/creat.2
@@ -0,0 +1 @@
+.so man2/open.2
diff --git a/man/man2/create_module.2 b/man/man2/create_module.2
new file mode 100644
index 000000000..1121713a8
--- /dev/null
+++ b/man/man2/create_module.2
@@ -0,0 +1,72 @@
+.\" Copyright (C) 1996 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" 2006-02-09, some reformatting by Luc Van Oostenryck; some
+.\" reformatting and rewordings by mtk
+.\"
+.TH create_module 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+create_module \- create a loadable module entry
+.SH SYNOPSIS
+.nf
+.B #include <linux/module.h>
+.P
+.BI "[[deprecated]] caddr_t create_module(const char *" name ", size_t " size );
+.fi
+.SH DESCRIPTION
+.IR Note :
+This system call is present only before Linux 2.6.
+.P
+.BR create_module ()
+attempts to create a loadable module entry and reserve the kernel memory
+that will be needed to hold the module.
+This system call requires privilege.
+.SH RETURN VALUE
+On success, returns the kernel address at which the module will reside.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EEXIST
+A module by that name already exists.
+.TP
+.B EFAULT
+.I name
+is outside the program's accessible address space.
+.TP
+.B EINVAL
+The requested size is too small even for the module header information.
+.TP
+.B ENOMEM
+The kernel could not allocate a contiguous block of memory large
+enough for the module.
+.TP
+.B ENOSYS
+.BR create_module ()
+is not supported in this version of the kernel
+(e.g., Linux 2.6 or later).
+.TP
+.B EPERM
+The caller was not privileged
+(did not have the
+.B CAP_SYS_MODULE
+capability).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Removed in Linux 2.6.
+.\" Removed in Linux 2.5.48
+.P
+This obsolete system call is not supported by glibc.
+No declaration is provided in glibc headers, but, through a quirk of history,
+glibc versions before glibc 2.23 did export an ABI for this system call.
+Therefore, in order to employ this system call,
+it was sufficient to manually declare the interface in your code;
+alternatively, you could invoke the system call using
+.BR syscall (2).
+.SH SEE ALSO
+.BR delete_module (2),
+.BR init_module (2),
+.BR query_module (2)
diff --git a/man/man2/delete_module.2 b/man/man2/delete_module.2
new file mode 100644
index 000000000..e9c432e84
--- /dev/null
+++ b/man/man2/delete_module.2
@@ -0,0 +1,205 @@
+.\" Copyright (C) 2012 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH delete_module 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+delete_module \- unload a kernel module
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" "            /* Definition of " O_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_delete_module, const char *" name ", unsigned int " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR delete_module (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR delete_module ()
+system call attempts to remove the unused loadable module entry
+identified by
+.IR name .
+If the module has an
+.I exit
+function, then that function is executed before unloading the module.
+The
+.I flags
+argument is used to modify the behavior of the system call,
+as described below.
+This system call requires privilege.
+.P
+Module removal is attempted according to the following rules:
+.IP (1) 5
+If there are other loaded modules that depend on
+(i.e., refer to symbols defined in) this module,
+then the call fails.
+.IP (2)
+Otherwise, if the reference count for the module
+(i.e., the number of processes currently using the module)
+is zero, then the module is immediately unloaded.
+.IP (3)
+If a module has a nonzero reference count,
+then the behavior depends on the bits set in
+.IR flags .
+In normal usage (see NOTES), the
+.B O_NONBLOCK
+flag is always specified, and the
+.B O_TRUNC
+flag may additionally be specified.
+.\"  	O_TRUNC == KMOD_REMOVE_FORCE in kmod library
+.\"  	O_NONBLOCK == KMOD_REMOVE_NOWAIT in kmod library
+.IP
+The various combinations for
+.I flags
+have the following effect:
+.RS
+.TP
+.B flags == O_NONBLOCK
+The call returns immediately, with an error.
+.TP
+.B flags == (O_NONBLOCK | O_TRUNC)
+The module is unloaded immediately,
+regardless of whether it has a nonzero reference count.
+.TP
+.B (flags & O_NONBLOCK) == 0
+If
+.I flags
+does not specify
+.BR O_NONBLOCK ,
+the following steps occur:
+.RS
+.IP \[bu] 3
+The module is marked so that no new references are permitted.
+.IP \[bu]
+If the module's reference count is nonzero,
+the caller is placed in an uninterruptible sleep state
+.RB ( TASK_UNINTERRUPTIBLE )
+until the reference count is zero, at which point the call unblocks.
+.IP \[bu]
+The module is unloaded in the usual way.
+.RE
+.RE
+.P
+The
+.B O_TRUNC
+flag has one further effect on the rules described above.
+By default, if a module has an
+.I init
+function but no
+.I exit
+function, then an attempt to remove the module fails.
+However, if
+.B O_TRUNC
+was specified, this requirement is bypassed.
+.P
+Using the
+.B O_TRUNC
+flag is dangerous!
+If the kernel was not built with
+.BR CONFIG_MODULE_FORCE_UNLOAD ,
+this flag is silently ignored.
+(Normally,
+.B CONFIG_MODULE_FORCE_UNLOAD
+is enabled.)
+Using this flag taints the kernel (TAINT_FORCED_RMMOD).
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBUSY
+The module is not "live"
+(i.e., it is still being initialized or is already marked for removal);
+or, the module has
+an
+.I init
+function but has no
+.I exit
+function, and
+.B O_TRUNC
+was not specified in
+.IR flags .
+.TP
+.B EFAULT
+.I name
+refers to a location outside the process's accessible address space.
+.TP
+.B ENOENT
+No module by that name exists.
+.TP
+.B EPERM
+The caller was not privileged
+(did not have the
+.B CAP_SYS_MODULE
+capability),
+or module unloading is disabled
+(see
+.I /proc/sys/kernel/modules_disabled
+in
+.BR proc (5)).
+.TP
+.B EWOULDBLOCK
+Other modules depend on this module;
+or,
+.B O_NONBLOCK
+was specified in
+.IR flags ,
+but the reference count of this module is nonzero and
+.B O_TRUNC
+was not specified in
+.IR flags .
+.SH STANDARDS
+Linux.
+.SH HISTORY
+The
+.BR delete_module ()
+system call is not supported by glibc.
+No declaration is provided in glibc headers, but, through a quirk of history,
+glibc versions before glibc 2.23 did export an ABI for this system call.
+Therefore, in order to employ this system call,
+it is (before glibc 2.23) sufficient to
+manually declare the interface in your code;
+alternatively, you can invoke the system call using
+.BR syscall (2).
+.SS Linux 2.4 and earlier
+In Linux 2.4 and earlier, the system call took only one argument:
+.P
+.BI "   int delete_module(const char *" name );
+.P
+If
+.I name
+is NULL, all unused modules marked auto-clean are removed.
+.P
+Some further details of differences in the behavior of
+.BR delete_module ()
+in Linux 2.4 and earlier are
+.I not
+currently explained in this manual page.
+.SH NOTES
+The uninterruptible sleep that may occur if
+.B O_NONBLOCK
+is omitted from
+.I flags
+is considered undesirable, because the sleeping process is left
+in an unkillable state.
+As at Linux 3.7, specifying
+.B O_NONBLOCK
+is optional, but in future kernels it is likely to become mandatory.
+.SH SEE ALSO
+.BR create_module (2),
+.BR init_module (2),
+.BR query_module (2),
+.BR lsmod (8),
+.BR modprobe (8),
+.BR rmmod (8)
diff --git a/man/man2/dup.2 b/man/man2/dup.2
new file mode 100644
index 000000000..4948e6dd4
--- /dev/null
+++ b/man/man2/dup.2
@@ -0,0 +1,284 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\" and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\" and Copyright (C) 2005, 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-21, Rik Faith <faith@cs.unc.edu>
+.\" Modified 1994-08-21, Michael Chastain <mec@shell.portal.com>:
+.\"   Fixed typos.
+.\" Modified 1997-01-31, Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2002-09-28, aeb
+.\" 2009-01-12, mtk, reordered text in DESCRIPTION and added some
+.\"     details for dup2().
+.\" 2008-10-09, mtk: add description of dup3()
+.\"
+.TH dup 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dup, dup2, dup3 \- duplicate a file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int dup(int " oldfd );
+.BI "int dup2(int " oldfd ", int " newfd );
+.P
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.BR "#include <fcntl.h>" "              /* Definition of " O_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int dup3(int " oldfd ", int " newfd ", int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR dup ()
+system call allocates a new file descriptor that refers to the same
+open file description as the descriptor
+.IR oldfd .
+(For an explanation of open file descriptions, see
+.BR open (2).)
+The new file descriptor number is guaranteed to be the lowest-numbered
+file descriptor that was unused in the calling process.
+.P
+After a successful return,
+the old and new file descriptors may be used interchangeably.
+Since the two file descriptors refer to the same open file description,
+they share file offset and file status flags;
+for example, if the file offset is modified by using
+.BR lseek (2)
+on one of the file descriptors,
+the offset is also changed for the other file descriptor.
+.P
+The two file descriptors do not share file descriptor flags
+(the close-on-exec flag).
+The close-on-exec flag
+.RB ( FD_CLOEXEC ;
+see
+.BR fcntl (2))
+for the duplicate descriptor is off.
+.\"
+.SS dup2()
+The
+.BR dup2 ()
+system call performs the same task as
+.BR dup (),
+but instead of using the lowest-numbered unused file descriptor,
+it uses the file descriptor number specified in
+.IR newfd .
+In other words,
+the file descriptor
+.I newfd
+is adjusted so that it now refers to the same open file description as
+.IR oldfd .
+.P
+If the file descriptor
+.I newfd
+was previously open, it is closed before being reused;
+the close is performed silently
+(i.e., any errors during the close are not reported by
+.BR dup2 ()).
+.P
+The steps of closing and reusing the file descriptor
+.I newfd
+are performed
+.IR atomically .
+This is important, because trying to implement equivalent functionality using
+.BR close (2)
+and
+.BR dup ()
+would be
+subject to race conditions, whereby
+.I newfd
+might be reused between the two steps.
+Such reuse could happen because the main program is interrupted
+by a signal handler that allocates a file descriptor,
+or because a parallel thread allocates a file descriptor.
+.P
+Note the following points:
+.IP \[bu] 3
+If
+.I oldfd
+is not a valid file descriptor, then the call fails, and
+.I newfd
+is not closed.
+.IP \[bu]
+If
+.I oldfd
+is a valid file descriptor, and
+.I newfd
+has the same value as
+.IR oldfd ,
+then
+.BR dup2 ()
+does nothing, and returns
+.IR newfd .
+.\"
+.SS dup3()
+.BR dup3 ()
+is the same as
+.BR dup2 (),
+except that:
+.IP \[bu] 3
+The caller can force the close-on-exec flag to be set
+for the new file descriptor by specifying
+.B O_CLOEXEC
+in
+.IR flags .
+See the description of the same flag in
+.BR open (2)
+for reasons why this may be useful.
+.IP \[bu]
+.\" Ulrich Drepper, LKML, 2008-10-09:
+.\"	We deliberately decided on this change.  Otherwise, what is the
+.\"	result of dup3(fd, fd, O_CLOEXEC)?
+If
+.I oldfd
+equals
+.IR newfd ,
+then
+.BR dup3 ()
+fails with the error
+.BR EINVAL .
+.SH RETURN VALUE
+On success, these system calls
+return the new file descriptor.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I oldfd
+isn't an open file descriptor.
+.TP
+.B EBADF
+.I newfd
+is out of the allowed range for file descriptors (see the discussion of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2)).
+.TP
+.B EBUSY
+(Linux only) This may be returned by
+.BR dup2 ()
+or
+.BR dup3 ()
+during a race condition with
+.BR open (2)
+and
+.BR dup ().
+.TP
+.B EINTR
+The
+.BR dup2 ()
+or
+.BR dup3 ()
+call was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EINVAL
+.RB ( dup3 ())
+.I flags
+contain an invalid value.
+.TP
+.B EINVAL
+.RB ( dup3 ())
+.I oldfd
+was equal to
+.IR newfd .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached
+(see the discussion of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2)).
+.SH STANDARDS
+.TP
+.BR dup ()
+.TQ
+.BR dup2 ()
+POSIX.1-2008.
+.TP
+.BR dup3 ()
+Linux.
+.SH HISTORY
+.TP
+.BR dup ()
+.TQ
+.BR dup2 ()
+POSIX.1-2001, SVr4, 4.3BSD.
+.\" SVr4 documents additional
+.\" EINTR and ENOLINK error conditions.  POSIX.1 adds EINTR.
+.\" The EBUSY return is Linux-specific.
+.TP
+.BR dup3 ()
+Linux 2.6.27,
+glibc 2.9.
+.SH NOTES
+The error returned by
+.BR dup2 ()
+is different from that returned by
+.BR fcntl( "..., " F_DUPFD ", ..." )
+when
+.I newfd
+is out of range.
+On some systems,
+.BR dup2 ()
+also sometimes returns
+.B EINVAL
+like
+.BR F_DUPFD .
+.P
+If
+.I newfd
+was open, any errors that would have been reported at
+.BR close (2)
+time are lost.
+If this is of concern,
+then\[em]unless the program is single-threaded and does not allocate
+file descriptors in signal handlers\[em]the correct approach is
+.I not
+to close
+.I newfd
+before calling
+.BR dup2 (),
+because of the race condition described above.
+Instead, code something like the following could be used:
+.P
+.in +4n
+.EX
+/* Obtain a duplicate of \[aq]newfd\[aq] that can subsequently
+   be used to check for close() errors; an EBADF error
+   means that \[aq]newfd\[aq] was not open. */
+\&
+tmpfd = dup(newfd);
+if (tmpfd == \-1 && errno != EBADF) {
+    /* Handle unexpected dup() error. */
+}
+\&
+/* Atomically duplicate \[aq]oldfd\[aq] on \[aq]newfd\[aq]. */
+\&
+if (dup2(oldfd, newfd) == \-1) {
+    /* Handle dup2() error. */
+}
+\&
+/* Now check for close() errors on the file originally
+   referred to by \[aq]newfd\[aq]. */
+\&
+if (tmpfd != \-1) {
+    if (close(tmpfd) == \-1) {
+        /* Handle errors from close. */
+    }
+}
+.EE
+.in
+.SH SEE ALSO
+.BR close (2),
+.BR fcntl (2),
+.BR open (2),
+.BR pidfd_getfd (2)
diff --git a/man/man2/dup2.2 b/man/man2/dup2.2
new file mode 100644
index 000000000..49a65c65d
--- /dev/null
+++ b/man/man2/dup2.2
@@ -0,0 +1 @@
+.so man2/dup.2
diff --git a/man/man2/dup3.2 b/man/man2/dup3.2
new file mode 100644
index 000000000..49a65c65d
--- /dev/null
+++ b/man/man2/dup3.2
@@ -0,0 +1 @@
+.so man2/dup.2
diff --git a/man/man2/epoll_create.2 b/man/man2/epoll_create.2
new file mode 100644
index 000000000..f0327e8ba
--- /dev/null
+++ b/man/man2/epoll_create.2
@@ -0,0 +1,144 @@
+.\"  Copyright (C) 2003  Davide Libenzi
+.\" and Copyright 2008, 2009, 2012 Michael Kerrisk <tk.manpages@gmail.com>
+.\"  Davide Libenzi <davidel@xmailserver.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2005-04-04 by Marko Kohtala <marko.kohtala@gmail.com>
+.\" 2008-10-10, mtk: add description of epoll_create1()
+.\"
+.TH epoll_create 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+epoll_create, epoll_create1 \- open an epoll file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/epoll.h>
+.P
+.BI "int epoll_create(int " size );
+.BI "int epoll_create1(int " flags );
+.fi
+.SH DESCRIPTION
+.BR epoll_create ()
+creates a new
+.BR epoll (7)
+instance.
+Since Linux 2.6.8, the
+.I size
+argument is ignored, but must be greater than zero; see HISTORY.
+.P
+.BR epoll_create ()
+returns a file descriptor referring to the new epoll instance.
+This file descriptor is used for all the subsequent calls to the
+.B epoll
+interface.
+When no longer required, the file descriptor returned by
+.BR epoll_create ()
+should be closed by using
+.BR close (2).
+When all file descriptors referring to an epoll instance have been closed,
+the kernel destroys the instance
+and releases the associated resources for reuse.
+.SS epoll_create1()
+If
+.I flags
+is 0, then, other than the fact that the obsolete
+.I size
+argument is dropped,
+.BR epoll_create1 ()
+is the same as
+.BR epoll_create ().
+The following value can be included in
+.I flags
+to obtain different behavior:
+.TP
+.B EPOLL_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.SH RETURN VALUE
+On success,
+these system calls
+return a file descriptor (a nonnegative integer).
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I size
+is not positive.
+.TP
+.B EINVAL
+.RB ( epoll_create1 ())
+Invalid value specified in
+.IR flags .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+There was insufficient memory to create the kernel object.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR epoll_create ()
+Linux 2.6,
+glibc 2.3.2.
+.\" To be precise: kernel 2.5.44.
+.\" The interface should be finalized by Linux kernel 2.5.66.
+.TP
+.BR epoll_create1 ()
+Linux 2.6.27,
+glibc 2.9.
+.P
+In the initial
+.BR epoll_create ()
+implementation, the
+.I size
+argument informed the kernel of the number of file descriptors
+that the caller expected to add to the
+.B epoll
+instance.
+The kernel used this information as a hint for the amount of
+space to initially allocate in internal data structures describing events.
+(If necessary, the kernel would allocate more space
+if the caller's usage exceeded the hint given in
+.IR size .)
+Nowadays,
+this hint is no longer required
+(the kernel dynamically sizes the required data structures
+without needing the hint), but
+.I size
+must still be greater than zero,
+in order to ensure backward compatibility when new
+.B epoll
+applications are run on older kernels.
+.P
+Prior to Linux 2.6.29,
+.\" commit 9df04e1f25effde823a600e755b51475d438f56b
+a
+.I /proc/sys/fs/epoll/max_user_instances
+kernel parameter limited live epolls for each real user ID,
+and caused
+.BR epoll_create ()
+to fail with
+.B EMFILE
+on overrun.
+.SH SEE ALSO
+.BR close (2),
+.BR epoll_ctl (2),
+.BR epoll_wait (2),
+.BR epoll (7)
diff --git a/man/man2/epoll_create1.2 b/man/man2/epoll_create1.2
new file mode 100644
index 000000000..69605b6ef
--- /dev/null
+++ b/man/man2/epoll_create1.2
@@ -0,0 +1 @@
+.so man2/epoll_create.2
diff --git a/man/man2/epoll_ctl.2 b/man/man2/epoll_ctl.2
new file mode 100644
index 000000000..6d5bc032e
--- /dev/null
+++ b/man/man2/epoll_ctl.2
@@ -0,0 +1,429 @@
+.\"  Copyright (C) 2003  Davide Libenzi
+.\"  Davide Libenzi <davidel@xmailserver.org>
+.\" and Copyright 2009, 2014, 2016, 2018, 2019 Michael Kerrisk <tk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH epoll_ctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+epoll_ctl \- control interface for an epoll file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/epoll.h>
+.P
+.BI "int epoll_ctl(int " epfd ", int " op ", int " fd ,
+.BI "              struct epoll_event *_Nullable " event );
+.fi
+.SH DESCRIPTION
+This system call is used to add, modify, or remove
+entries in the interest list of the
+.BR epoll (7)
+instance
+referred to by the file descriptor
+.IR epfd .
+It requests that the operation
+.I op
+be performed for the target file descriptor,
+.IR fd .
+.P
+Valid values for the
+.I op
+argument are:
+.TP
+.B EPOLL_CTL_ADD
+Add an entry to the interest list of the epoll file descriptor,
+.IR epfd .
+The entry includes the file descriptor,
+.IR fd ,
+a reference to the corresponding open file description (see
+.BR epoll (7)
+and
+.BR open (2)),
+and the settings specified in
+.IR event .
+.TP
+.B EPOLL_CTL_MOD
+Change the settings associated with
+.I fd
+in the interest list to the new settings specified in
+.IR event .
+.TP
+.B EPOLL_CTL_DEL
+Remove (deregister) the target file descriptor
+.I fd
+from the interest list.
+The
+.I event
+argument is ignored and can be NULL (but see BUGS below).
+.P
+The
+.I event
+argument describes the object linked to the file descriptor
+.IR fd .
+The
+.I struct epoll_event
+is described in
+.BR epoll_event (3type).
+.P
+The
+.I data
+member of the
+.I epoll_event
+structure specifies data that the kernel should save and then return (via
+.BR epoll_wait (2))
+when this file descriptor becomes ready.
+.P
+The
+.I events
+member of the
+.I epoll_event
+structure is a bit mask composed by ORing together zero or more event types,
+returned by
+.BR epoll_wait (2),
+and input flags, which affect its behaviour, but aren't returned.
+The available event types are:
+.TP
+.B EPOLLIN
+The associated file is available for
+.BR read (2)
+operations.
+.TP
+.B EPOLLOUT
+The associated file is available for
+.BR write (2)
+operations.
+.TP
+.BR EPOLLRDHUP " (since Linux 2.6.17)"
+Stream socket peer closed connection,
+or shut down writing half of connection.
+(This flag is especially useful for writing simple code to detect
+peer shutdown when using edge-triggered monitoring.)
+.TP
+.B EPOLLPRI
+There is an exceptional condition on the file descriptor.
+See the discussion of
+.B POLLPRI
+in
+.BR poll (2).
+.TP
+.B EPOLLERR
+Error condition happened on the associated file descriptor.
+This event is also reported for the write end of a pipe when the read end
+has been closed.
+.IP
+.BR epoll_wait (2)
+will always report for this event; it is not necessary to set it in
+.I events
+when calling
+.BR epoll_ctl ().
+.TP
+.B EPOLLHUP
+Hang up happened on the associated file descriptor.
+.IP
+.BR epoll_wait (2)
+will always wait for this event; it is not necessary to set it in
+.I events
+when calling
+.BR epoll_ctl ().
+.IP
+Note that when reading from a channel such as a pipe or a stream socket,
+this event merely indicates that the peer closed its end of the channel.
+Subsequent reads from the channel will return 0 (end of file)
+only after all outstanding data in the channel has been consumed.
+.P
+And the available input flags are:
+.TP
+.B EPOLLET
+Requests edge-triggered notification for the associated file descriptor.
+The default behavior for
+.B epoll
+is level-triggered.
+See
+.BR epoll (7)
+for more detailed information about edge-triggered and
+level-triggered notification.
+.TP
+.BR EPOLLONESHOT " (since Linux 2.6.2)"
+Requests one-shot notification for the associated file descriptor.
+This means that after an event notified for the file descriptor by
+.BR epoll_wait (2),
+the file descriptor is disabled in the interest list and no other events
+will be reported by the
+.B epoll
+interface.
+The user must call
+.BR epoll_ctl ()
+with
+.B EPOLL_CTL_MOD
+to rearm the file descriptor with a new event mask.
+.TP
+.BR EPOLLWAKEUP " (since Linux 3.5)"
+.\" commit 4d7e30d98939a0340022ccd49325a3d70f7e0238
+If
+.B EPOLLONESHOT
+and
+.B EPOLLET
+are clear and the process has the
+.B CAP_BLOCK_SUSPEND
+capability,
+ensure that the system does not enter "suspend" or
+"hibernate" while this event is pending or being processed.
+The event is considered as being "processed" from the time
+when it is returned by a call to
+.BR epoll_wait (2)
+until the next call to
+.BR epoll_wait (2)
+on the same
+.BR epoll (7)
+file descriptor,
+the closure of that file descriptor,
+the removal of the event file descriptor with
+.BR EPOLL_CTL_DEL ,
+or the clearing of
+.B EPOLLWAKEUP
+for the event file descriptor with
+.BR EPOLL_CTL_MOD .
+See also BUGS.
+.TP
+.BR EPOLLEXCLUSIVE " (since Linux 4.5)"
+Sets an exclusive wakeup mode for the epoll file descriptor that is being
+attached to the target file descriptor,
+.IR fd .
+When a wakeup event occurs and multiple epoll file descriptors
+are attached to the same target file using
+.BR EPOLLEXCLUSIVE ,
+one or more of the epoll file descriptors will receive an event with
+.BR epoll_wait (2).
+The default in this scenario (when
+.B EPOLLEXCLUSIVE
+is not set) is for all epoll file descriptors to receive an event.
+.B EPOLLEXCLUSIVE
+is thus useful for avoiding thundering herd problems in certain scenarios.
+.IP
+If the same file descriptor is in multiple epoll instances,
+some with the
+.B EPOLLEXCLUSIVE
+flag, and others without, then events will be provided to all epoll
+instances that did not specify
+.BR EPOLLEXCLUSIVE ,
+and at least one of the epoll instances that did specify
+.BR EPOLLEXCLUSIVE .
+.IP
+The following values may be specified in conjunction with
+.BR EPOLLEXCLUSIVE :
+.BR EPOLLIN ,
+.BR EPOLLOUT ,
+.BR EPOLLWAKEUP ,
+and
+.BR EPOLLET .
+.B EPOLLHUP
+and
+.B EPOLLERR
+can also be specified, but this is not required:
+as usual, these events are always reported if they occur,
+regardless of whether they are specified in
+.IR events .
+Attempts to specify other values in
+.I events
+yield the error
+.BR EINVAL .
+.IP
+.B EPOLLEXCLUSIVE
+may be used only in an
+.B EPOLL_CTL_ADD
+operation; attempts to employ it with
+.B EPOLL_CTL_MOD
+yield an error.
+If
+.B EPOLLEXCLUSIVE
+has been set using
+.BR epoll_ctl (),
+then a subsequent
+.B EPOLL_CTL_MOD
+on the same
+.IR epfd ,\~ fd
+pair yields an error.
+A call to
+.BR epoll_ctl ()
+that specifies
+.B EPOLLEXCLUSIVE
+in
+.I events
+and specifies the target file descriptor
+.I fd
+as an epoll instance will likewise fail.
+The error in all of these cases is
+.BR EINVAL .
+.SH RETURN VALUE
+When successful,
+.BR epoll_ctl ()
+returns zero.
+When an error occurs,
+.BR epoll_ctl ()
+returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I epfd
+or
+.I fd
+is not a valid file descriptor.
+.TP
+.B EEXIST
+.I op
+was
+.BR EPOLL_CTL_ADD ,
+and the supplied file descriptor
+.I fd
+is already registered with this epoll instance.
+.TP
+.B EINVAL
+.I epfd
+is not an
+.B epoll
+file descriptor,
+or
+.I fd
+is the same as
+.IR epfd ,
+or the requested operation
+.I op
+is not supported by this interface.
+.TP
+.B EINVAL
+An invalid event type was specified along with
+.B EPOLLEXCLUSIVE
+in
+.IR events .
+.TP
+.B EINVAL
+.I op
+was
+.B EPOLL_CTL_MOD
+and
+.I events
+included
+.BR EPOLLEXCLUSIVE .
+.TP
+.B EINVAL
+.I op
+was
+.B EPOLL_CTL_MOD
+and the
+.B EPOLLEXCLUSIVE
+flag has previously been applied to this
+.IR epfd ,\~ fd
+pair.
+.TP
+.B EINVAL
+.B EPOLLEXCLUSIVE
+was specified in
+.I event
+and
+.I fd
+refers to an epoll instance.
+.TP
+.B ELOOP
+.I fd
+refers to an epoll instance and this
+.B EPOLL_CTL_ADD
+operation would result in a circular loop of epoll instances
+monitoring one another or a nesting depth of epoll instances
+greater than 5.
+.TP
+.B ENOENT
+.I op
+was
+.B EPOLL_CTL_MOD
+or
+.BR EPOLL_CTL_DEL ,
+and
+.I fd
+is not registered with this epoll instance.
+.TP
+.B ENOMEM
+There was insufficient memory to handle the requested
+.I op
+control operation.
+.TP
+.B ENOSPC
+The limit imposed by
+.I /proc/sys/fs/epoll/max_user_watches
+was encountered while trying to register
+.RB ( EPOLL_CTL_ADD )
+a new file descriptor on an epoll instance.
+See
+.BR epoll (7)
+for further details.
+.TP
+.B EPERM
+The target file
+.I fd
+does not support
+.BR epoll .
+This error can occur if
+.I fd
+refers to, for example, a regular file or a directory.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6,
+.\" To be precise: Linux 2.5.44.
+.\" The interface should be finalized by Linux 2.5.66.
+glibc 2.3.2.
+.SH NOTES
+The
+.B epoll
+interface supports all file descriptors that support
+.BR poll (2).
+.SH BUGS
+Before Linux 2.6.9, the
+.B EPOLL_CTL_DEL
+operation required a non-null pointer in
+.IR event ,
+even though this argument is ignored.
+Since Linux 2.6.9,
+.I event
+can be specified as NULL
+when using
+.BR EPOLL_CTL_DEL .
+Applications that need to be portable to kernels before Linux 2.6.9
+should specify a non-null pointer in
+.IR event .
+.P
+If
+.B EPOLLWAKEUP
+is specified in
+.IR flags ,
+but the caller does not have the
+.B CAP_BLOCK_SUSPEND
+capability, then the
+.B EPOLLWAKEUP
+flag is
+.IR "silently ignored" .
+This unfortunate behavior is necessary because no validity
+checks were performed on the
+.I flags
+argument in the original implementation, and the addition of the
+.B EPOLLWAKEUP
+with a check that caused the call to fail if the caller did not have the
+.B CAP_BLOCK_SUSPEND
+capability caused a breakage in at least one existing user-space
+application that happened to randomly (and uselessly) specify this bit.
+.\" commit a8159414d7e3af7233e7a5a82d1c5d85379bd75c (behavior change)
+.\" https://lwn.net/Articles/520198/
+A robust application should therefore double check that it has the
+.B CAP_BLOCK_SUSPEND
+capability if attempting to use the
+.B EPOLLWAKEUP
+flag.
+.SH SEE ALSO
+.BR epoll_create (2),
+.BR epoll_wait (2),
+.BR poll (2),
+.BR epoll (7)
diff --git a/man/man2/epoll_pwait.2 b/man/man2/epoll_pwait.2
new file mode 100644
index 000000000..9282a7064
--- /dev/null
+++ b/man/man2/epoll_pwait.2
@@ -0,0 +1 @@
+.so man2/epoll_wait.2
diff --git a/man/man2/epoll_pwait2.2 b/man/man2/epoll_pwait2.2
new file mode 100644
index 000000000..9282a7064
--- /dev/null
+++ b/man/man2/epoll_pwait2.2
@@ -0,0 +1 @@
+.so man2/epoll_wait.2
diff --git a/man/man2/epoll_wait.2 b/man/man2/epoll_wait.2
new file mode 100644
index 000000000..20af75075
--- /dev/null
+++ b/man/man2/epoll_wait.2
@@ -0,0 +1,288 @@
+.\"  Copyright (C) 2003  Davide Libenzi
+.\"  Davide Libenzi <davidel@xmailserver.org>
+.\" and Copyright 2007, 2012, 2014, 2018 Michael Kerrisk <tk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2007-04-30: mtk, Added description of epoll_pwait()
+.\"
+.TH epoll_wait 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+epoll_wait, epoll_pwait, epoll_pwait2 \-
+wait for an I/O event on an epoll file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/epoll.h>
+.P
+.BI "int epoll_wait(int " epfd ", struct epoll_event *" events ,
+.BI "               int " maxevents ", int " timeout );
+.BI "int epoll_pwait(int " epfd ", struct epoll_event *" events ,
+.BI "               int " maxevents ", int " timeout ,
+.BI "               const sigset_t *_Nullable " sigmask );
+.BI "int epoll_pwait2(int " epfd ", struct epoll_event *" events ,
+.BI "               int " maxevents ", \
+const struct timespec *_Nullable " timeout ,
+.BI "               const sigset_t *_Nullable " sigmask );
+.fi
+.SH DESCRIPTION
+The
+.BR epoll_wait ()
+system call waits for events on the
+.BR epoll (7)
+instance referred to by the file descriptor
+.IR epfd .
+The buffer pointed to by
+.I events
+is used to return information from the ready list
+about file descriptors in the interest list that
+have some events available.
+Up to
+.I maxevents
+are returned by
+.BR epoll_wait ().
+The
+.I maxevents
+argument must be greater than zero.
+.P
+The
+.I timeout
+argument specifies the number of milliseconds that
+.BR epoll_wait ()
+will block.
+Time is measured against the
+.B CLOCK_MONOTONIC
+clock.
+.P
+A call to
+.BR epoll_wait ()
+will block until either:
+.IP \[bu] 3
+a file descriptor delivers an event;
+.IP \[bu]
+the call is interrupted by a signal handler; or
+.IP \[bu]
+the timeout expires.
+.P
+Note that the
+.I timeout
+interval will be rounded up to the system clock granularity,
+and kernel scheduling delays mean that the blocking interval
+may overrun by a small amount.
+Specifying a
+.I timeout
+of \-1 causes
+.BR epoll_wait ()
+to block indefinitely, while specifying a
+.I timeout
+equal to zero causes
+.BR epoll_wait ()
+to return immediately, even if no events are available.
+.P
+The
+.I struct epoll_event
+is described in
+.BR epoll_event (3type).
+.P
+The
+.I data
+field of each returned
+.I epoll_event
+structure contains the same data as was specified
+in the most recent call to
+.BR epoll_ctl (2)
+.RB ( EPOLL_CTL_ADD ", " EPOLL_CTL_MOD )
+for the corresponding open file descriptor.
+.P
+The
+.I events
+field is a bit mask that indicates the events that have occurred for the
+corresponding open file description.
+See
+.BR epoll_ctl (2)
+for a list of the bits that may appear in this mask.
+.\"
+.SS epoll_pwait()
+The relationship between
+.BR epoll_wait ()
+and
+.BR epoll_pwait ()
+is analogous to the relationship between
+.BR select (2)
+and
+.BR pselect (2):
+like
+.BR pselect (2),
+.BR epoll_pwait ()
+allows an application to safely wait until either a file descriptor
+becomes ready or until a signal is caught.
+.P
+The following
+.BR epoll_pwait ()
+call:
+.P
+.in +4n
+.EX
+ready = epoll_pwait(epfd, &events, maxevents, timeout, &sigmask);
+.EE
+.in
+.P
+is equivalent to
+.I atomically
+executing the following calls:
+.P
+.in +4n
+.EX
+sigset_t origmask;
+\&
+pthread_sigmask(SIG_SETMASK, &sigmask, &origmask);
+ready = epoll_wait(epfd, &events, maxevents, timeout);
+pthread_sigmask(SIG_SETMASK, &origmask, NULL);
+.EE
+.in
+.P
+The
+.I sigmask
+argument may be specified as NULL, in which case
+.BR epoll_pwait ()
+is equivalent to
+.BR epoll_wait ().
+.\"
+.SS epoll_pwait2()
+The
+.BR epoll_pwait2 ()
+system call is equivalent to
+.BR epoll_pwait ()
+except for the
+.I timeout
+argument.
+It takes an argument of type
+.I timespec
+to be able to specify nanosecond resolution timeout.
+This argument functions the same as in
+.BR pselect (2)
+and
+.BR ppoll (2).
+If
+.I timeout
+is NULL, then
+.BR epoll_pwait2 ()
+can block indefinitely.
+.SH RETURN VALUE
+On success,
+.BR epoll_wait ()
+returns the number of file descriptors ready for the requested I/O operation,
+or zero if no file descriptor became ready during the requested
+.I timeout
+milliseconds.
+On failure,
+.BR epoll_wait ()
+returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I epfd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+The memory area pointed to by
+.I events
+is not accessible with write permissions.
+.TP
+.B EINTR
+The call was interrupted by a signal handler before either (1) any of the
+requested events occurred or (2) the
+.I timeout
+expired; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I epfd
+is not an
+.B epoll
+file descriptor, or
+.I maxevents
+is less than or equal to zero.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR epoll_wait ()
+Linux 2.6,
+.\" To be precise: Linux 2.5.44.
+.\" The interface should be finalized by Linux 2.5.66.
+glibc 2.3.2.
+.TP
+.BR epoll_pwait ()
+Linux 2.6.19,
+glibc 2.6.
+.TP
+.BR epoll_pwait2 ()
+Linux 5.11.
+.SH NOTES
+While one thread is blocked in a call to
+.BR epoll_wait (),
+it is possible for another thread to add a file descriptor to the waited-upon
+.B epoll
+instance.
+If the new file descriptor becomes ready,
+it will cause the
+.BR epoll_wait ()
+call to unblock.
+.P
+If more than
+.I maxevents
+file descriptors are ready when
+.BR epoll_wait ()
+is called, then successive
+.BR epoll_wait ()
+calls will round robin through the set of ready file descriptors.
+This behavior helps avoid starvation scenarios,
+where a process fails to notice that additional file descriptors
+are ready because it focuses on a set of file descriptors that
+are already known to be ready.
+.P
+Note that it is possible to call
+.BR epoll_wait ()
+on an
+.B epoll
+instance whose interest list is currently empty
+(or whose interest list becomes empty because file descriptors are closed
+or removed from the interest in another thread).
+The call will block until some file descriptor is later added to the
+interest list (in another thread) and that file descriptor becomes ready.
+.SS C library/kernel differences
+The raw
+.BR epoll_pwait ()
+and
+.BR epoll_pwait2 ()
+system calls have a sixth argument,
+.IR "size_t sigsetsize" ,
+which specifies the size in bytes of the
+.I sigmask
+argument.
+The glibc
+.BR epoll_pwait ()
+wrapper function specifies this argument as a fixed value
+(equal to
+.IR sizeof(sigset_t) ).
+.SH BUGS
+Before Linux 2.6.37, a
+.I timeout
+value larger than approximately
+.I LONG_MAX / HZ
+milliseconds is treated as \-1 (i.e., infinity).
+Thus, for example, on a system where
+.I sizeof(long)
+is 4 and the kernel
+.I HZ
+value is 1000,
+this means that timeouts greater than 35.79 minutes are treated as infinity.
+.SH SEE ALSO
+.BR epoll_create (2),
+.BR epoll_ctl (2),
+.BR epoll (7)
diff --git a/man/man2/eventfd.2 b/man/man2/eventfd.2
new file mode 100644
index 000000000..3b67239ac
--- /dev/null
+++ b/man/man2/eventfd.2
@@ -0,0 +1,446 @@
+'\" t
+.\" Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" starting from a version by Davide Libenzi <davidel@xmailserver.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2008-10-10, mtk: describe eventfd2(), and EFD_NONBLOCK and EFD_CLOEXEC
+.\"
+.TH eventfd 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+eventfd \- create a file descriptor for event notification
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/eventfd.h>
+.P
+.BI "int eventfd(unsigned int " initval ", int " flags );
+.fi
+.SH DESCRIPTION
+.BR eventfd ()
+creates an "eventfd object" that can be used as
+an event wait/notify mechanism by user-space applications,
+and by the kernel to notify user-space applications of events.
+The object contains an unsigned 64-bit integer
+.RI ( uint64_t )
+counter that is maintained by the kernel.
+This counter is initialized with the value specified in the argument
+.IR initval .
+.P
+As its return value,
+.BR eventfd ()
+returns a new file descriptor that can be used to refer to the
+eventfd object.
+.P
+The following values may be bitwise ORed in
+.I flags
+to change the behavior of
+.BR eventfd ():
+.TP
+.BR EFD_CLOEXEC " (since Linux 2.6.27)"
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.TP
+.BR EFD_NONBLOCK " (since Linux 2.6.27)"
+Set the
+.B O_NONBLOCK
+file status flag on the open file description (see
+.BR open (2))
+referred to by the new file descriptor.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
+.TP
+.BR EFD_SEMAPHORE " (since Linux 2.6.30)"
+Provide semaphore-like semantics for reads from the new file descriptor.
+See below.
+.P
+Up to Linux 2.6.26, the
+.I flags
+argument is unused, and must be specified as zero.
+.P
+The following operations can be performed on the file descriptor returned by
+.BR eventfd ():
+.TP
+.BR read (2)
+Each successful
+.BR read (2)
+returns an 8-byte integer.
+A
+.BR read (2)
+fails with the error
+.B EINVAL
+if the size of the supplied buffer is less than 8 bytes.
+.IP
+The value returned by
+.BR read (2)
+is in host byte order\[em]that is,
+the native byte order for integers on the host machine.
+.IP
+The semantics of
+.BR read (2)
+depend on whether the eventfd counter currently has a nonzero value
+and whether the
+.B EFD_SEMAPHORE
+flag was specified when creating the eventfd file descriptor:
+.RS
+.IP \[bu] 3
+If
+.B EFD_SEMAPHORE
+was not specified and the eventfd counter has a nonzero value, then a
+.BR read (2)
+returns 8 bytes containing that value,
+and the counter's value is reset to zero.
+.IP \[bu]
+If
+.B EFD_SEMAPHORE
+was specified and the eventfd counter has a nonzero value, then a
+.BR read (2)
+returns 8 bytes containing the value 1,
+and the counter's value is decremented by 1.
+.IP \[bu]
+If the eventfd counter is zero at the time of the call to
+.BR read (2),
+then the call either blocks until the counter becomes nonzero
+(at which time, the
+.BR read (2)
+proceeds as described above)
+or fails with the error
+.B EAGAIN
+if the file descriptor has been made nonblocking.
+.RE
+.TP
+.BR write (2)
+A
+.BR write (2)
+call adds the 8-byte integer value supplied in its
+buffer to the counter.
+The maximum value that may be stored in the counter is the largest
+unsigned 64-bit value minus 1 (i.e., 0xfffffffffffffffe).
+If the addition would cause the counter's value to exceed
+the maximum, then the
+.BR write (2)
+either blocks until a
+.BR read (2)
+is performed on the file descriptor,
+or fails with the error
+.B EAGAIN
+if the file descriptor has been made nonblocking.
+.IP
+A
+.BR write (2)
+fails with the error
+.B EINVAL
+if the size of the supplied buffer is less than 8 bytes,
+or if an attempt is made to write the value 0xffffffffffffffff.
+.TP
+.BR poll (2)
+.TQ
+.BR select (2)
+.TQ
+(and similar)
+The returned file descriptor supports
+.BR poll (2)
+(and analogously
+.BR epoll (7))
+and
+.BR select (2),
+as follows:
+.RS
+.IP \[bu] 3
+The file descriptor is readable
+(the
+.BR select (2)
+.I readfds
+argument; the
+.BR poll (2)
+.B POLLIN
+flag)
+if the counter has a value greater than 0.
+.IP \[bu]
+The file descriptor is writable
+(the
+.BR select (2)
+.I writefds
+argument; the
+.BR poll (2)
+.B POLLOUT
+flag)
+if it is possible to write a value of at least "1" without blocking.
+.IP \[bu]
+If an overflow of the counter value was detected,
+then
+.BR select (2)
+indicates the file descriptor as being both readable and writable, and
+.BR poll (2)
+returns a
+.B POLLERR
+event.
+As noted above,
+.BR write (2)
+can never overflow the counter.
+However an overflow can occur if 2\[ha]64
+eventfd "signal posts" were performed by the KAIO
+subsystem (theoretically possible, but practically unlikely).
+If an overflow has occurred, then
+.BR read (2)
+will return that maximum
+.I uint64_t
+value (i.e., 0xffffffffffffffff).
+.RE
+.IP
+The eventfd file descriptor also supports the other file-descriptor
+multiplexing APIs:
+.BR pselect (2)
+and
+.BR ppoll (2).
+.TP
+.BR close (2)
+When the file descriptor is no longer required it should be closed.
+When all file descriptors associated with the same eventfd object
+have been closed, the resources for object are freed by the kernel.
+.P
+A copy of the file descriptor created by
+.BR eventfd ()
+is inherited by the child produced by
+.BR fork (2).
+The duplicate file descriptor is associated with the same
+eventfd object.
+File descriptors created by
+.BR eventfd ()
+are preserved across
+.BR execve (2),
+unless the close-on-exec flag has been set.
+.SH RETURN VALUE
+On success,
+.BR eventfd ()
+returns a new eventfd file descriptor.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+An unsupported value was specified in
+.IR flags .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been
+reached.
+.TP
+.B ENODEV
+.\" Note from Davide:
+.\" The ENODEV error is basically never going to happen if
+.\" the kernel boots correctly. That error happen only if during
+.\" the kernel initialization, some error occur in the anonymous
+.\" inode source initialization.
+Could not mount (internal) anonymous inode device.
+.TP
+.B ENOMEM
+There was insufficient memory to create a new
+eventfd file descriptor.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR eventfd ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.SS C library/kernel differences
+There are two underlying Linux system calls:
+.BR eventfd ()
+and the more recent
+.BR eventfd2 ().
+The former system call does not implement a
+.I flags
+argument.
+The latter system call implements the
+.I flags
+values described above.
+The glibc wrapper function will use
+.BR eventfd2 ()
+where it is available.
+.SS Additional glibc features
+The GNU C library defines an additional type,
+and two functions that attempt to abstract some of the details of
+reading and writing on an eventfd file descriptor:
+.P
+.in +4n
+.EX
+typedef uint64_t eventfd_t;
+\&
+int eventfd_read(int fd, eventfd_t *value);
+int eventfd_write(int fd, eventfd_t value);
+.EE
+.in
+.P
+The functions perform the read and write operations on an
+eventfd file descriptor,
+returning 0 if the correct number of bytes was transferred,
+or \-1 otherwise.
+.SH STANDARDS
+Linux, GNU.
+.SH HISTORY
+.TP
+.BR eventfd ()
+Linux 2.6.22,
+glibc 2.8.
+.\" eventfd() is in glibc 2.7, but reportedly does not build
+.TP
+.BR eventfd2 ()
+Linux 2.6.27 (see VERSIONS).
+Since glibc 2.9, the
+.BR eventfd ()
+wrapper will employ the
+.BR eventfd2 ()
+system call, if it is supported by the kernel.
+.SH NOTES
+Applications can use an eventfd file descriptor instead of a pipe (see
+.BR pipe (2))
+in all cases where a pipe is used simply to signal events.
+The kernel overhead of an eventfd file descriptor
+is much lower than that of a pipe,
+and only one file descriptor is
+required (versus the two required for a pipe).
+.P
+When used in the kernel, an eventfd
+file descriptor can provide a bridge from kernel to user space, allowing,
+for example, functionalities like KAIO (kernel AIO)
+.\" or eventually syslets/threadlets
+to signal to a file descriptor that some operation is complete.
+.P
+A key point about an eventfd file descriptor is that it can be
+monitored just like any other file descriptor using
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7).
+This means that an application can simultaneously monitor the
+readiness of "traditional" files and the readiness of other
+kernel mechanisms that support the eventfd interface.
+(Without the
+.BR eventfd ()
+interface, these mechanisms could not be multiplexed via
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7).)
+.P
+The current value of an eventfd counter can be viewed
+via the entry for the corresponding file descriptor in the process's
+.IR /proc/ pid /fdinfo
+directory.
+See
+.BR proc (5)
+for further details.
+.SH EXAMPLES
+The following program creates an eventfd file descriptor
+and then forks to create a child process.
+While the parent briefly sleeps,
+the child writes each of the integers supplied in the program's
+command-line arguments to the eventfd file descriptor.
+When the parent has finished sleeping,
+it reads from the eventfd file descriptor.
+.P
+The following shell session shows a sample run of the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 1 2 4 7 14"
+Child writing 1 to efd
+Child writing 2 to efd
+Child writing 4 to efd
+Child writing 7 to efd
+Child writing 14 to efd
+Child completed write loop
+Parent about to read
+Parent read 28 (0x1c) from efd
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (eventfd.c)
+.EX
+#include <err.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/eventfd.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int       efd;
+    uint64_t  u;
+    ssize_t   s;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <num>...\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    efd = eventfd(0, 0);
+    if (efd == \-1)
+        err(EXIT_FAILURE, "eventfd");
+\&
+    switch (fork()) {
+    case 0:
+        for (size_t j = 1; j < argc; j++) {
+            printf("Child writing %s to efd\en", argv[j]);
+            u = strtoull(argv[j], NULL, 0);
+                    /* strtoull() allows various bases */
+            s = write(efd, &u, sizeof(uint64_t));
+            if (s != sizeof(uint64_t))
+                err(EXIT_FAILURE, "write");
+        }
+        printf("Child completed write loop\en");
+\&
+        exit(EXIT_SUCCESS);
+\&
+    default:
+        sleep(2);
+\&
+        printf("Parent about to read\en");
+        s = read(efd, &u, sizeof(uint64_t));
+        if (s != sizeof(uint64_t))
+            err(EXIT_FAILURE, "read");
+        printf("Parent read %"PRIu64" (%#"PRIx64") from efd\en", u, u);
+        exit(EXIT_SUCCESS);
+\&
+    case \-1:
+        err(EXIT_FAILURE, "fork");
+    }
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR futex (2),
+.BR pipe (2),
+.BR poll (2),
+.BR read (2),
+.BR select (2),
+.BR signalfd (2),
+.BR timerfd_create (2),
+.BR write (2),
+.BR epoll (7),
+.BR sem_overview (7)
diff --git a/man/man2/eventfd2.2 b/man/man2/eventfd2.2
new file mode 100644
index 000000000..eddfaa8a1
--- /dev/null
+++ b/man/man2/eventfd2.2
@@ -0,0 +1 @@
+.so man2/eventfd.2
diff --git a/man/man2/execve.2 b/man/man2/execve.2
new file mode 100644
index 000000000..03dfdcdcf
--- /dev/null
+++ b/man/man2/execve.2
@@ -0,0 +1,889 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\" and Copyright (c) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1994-08-21 by Michael Chastain <mec@shell.portal.com>:
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1999-11-12 by Urs Thuermann <urs@isnogud.escape.de>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2006-09-04 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added list of process attributes that are not preserved on exec().
+.\" 2007-09-14 Ollie Wild <aaw@google.com>, mtk
+.\"     Add text describing limits on command-line arguments + environment
+.\"
+.TH execve 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+execve \- execute program
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int execve(const char *" pathname ", char *const _Nullable " argv [],
+.BI "           char *const _Nullable " envp []);
+.fi
+.SH DESCRIPTION
+.BR execve ()
+executes the program referred to by \fIpathname\fP.
+This causes the program that is currently being run by the calling process
+to be replaced with a new program, with newly initialized stack, heap,
+and (initialized and uninitialized) data segments.
+.P
+\fIpathname\fP must be either a binary executable, or a script
+starting with a line of the form:
+.P
+.in +4n
+.EX
+\fB#!\fP\fIinterpreter \fP[optional-arg]
+.EE
+.in
+.P
+For details of the latter case, see "Interpreter scripts" below.
+.P
+.I argv
+is an array of pointers to strings passed to the new program
+as its command-line arguments.
+By convention, the first of these strings (i.e.,
+.IR argv[0] )
+should contain the filename associated with the file being executed.
+The
+.I argv
+array must be terminated by a null pointer.
+(Thus, in the new program,
+.I argv[argc]
+will be a null pointer.)
+.P
+.I envp
+is an array of pointers to strings, conventionally of the form
+.BR key=value ,
+which are passed as the environment of the new program.
+The
+.I envp
+array must be terminated by a null pointer.
+.P
+This manual page describes the Linux system call in detail;
+for an overview of the nomenclature and the many, often preferable,
+standardised variants of this function provided by libc,
+including ones that search the
+.B PATH
+environment variable, see
+.BR exec (3).
+.P
+The argument vector and environment can be accessed by the
+new program's main function, when it is defined as:
+.P
+.in +4n
+.EX
+int main(int argc, char *argv[], char *envp[])
+.EE
+.in
+.P
+Note, however, that the use of a third argument to the main function
+is not specified in POSIX.1;
+according to POSIX.1,
+the environment should be accessed via the external variable
+.BR environ (7).
+.P
+.BR execve ()
+does not return on success, and the text, initialized data,
+uninitialized data (bss), and stack of the calling process are overwritten
+according to the contents of the newly loaded program.
+.P
+If the current program is being ptraced, a \fBSIGTRAP\fP signal is sent to it
+after a successful
+.BR execve ().
+.P
+If the set-user-ID bit is set on the program file referred to by
+\fIpathname\fP,
+then the effective user ID of the calling process is changed
+to that of the owner of the program file.
+Similarly, if the set-group-ID bit is set on the program file,
+then the effective group ID of the calling
+process is set to the group of the program file.
+.P
+The aforementioned transformations of the effective IDs are
+.I not
+performed (i.e., the set-user-ID and set-group-ID bits are ignored)
+if any of the following is true:
+.IP \[bu] 3
+the
+.I no_new_privs
+attribute is set for the calling thread (see
+.BR prctl (2));
+.IP \[bu]
+the underlying filesystem is mounted
+.I nosuid
+(the
+.B MS_NOSUID
+flag for
+.BR mount (2));
+or
+.IP \[bu]
+the calling process is being ptraced.
+.P
+The capabilities of the program file (see
+.BR capabilities (7))
+are also ignored if any of the above are true.
+.P
+The effective user ID of the process is copied to the saved set-user-ID;
+similarly, the effective group ID is copied to the saved set-group-ID.
+This copying takes place after any effective ID changes that occur
+because of the set-user-ID and set-group-ID mode bits.
+.P
+The process's real UID and real GID, as well as its supplementary group IDs,
+are unchanged by a call to
+.BR execve ().
+.P
+If the executable is an a.out dynamically linked
+binary executable containing
+shared-library stubs, the Linux dynamic linker
+.BR ld.so (8)
+is called at the start of execution to bring
+needed shared objects into memory
+and link the executable with them.
+.P
+If the executable is a dynamically linked ELF executable, the
+interpreter named in the PT_INTERP segment is used to load the needed
+shared objects.
+This interpreter is typically
+.I /lib/ld\-linux.so.2
+for binaries linked with glibc (see
+.BR ld\-linux.so (8)).
+.\"
+.SS Effect on process attributes
+All process attributes are preserved during an
+.BR execve (),
+except the following:
+.IP \[bu] 3
+The dispositions of any signals that are being caught are
+reset to the default
+.RB ( signal (7)).
+.IP \[bu]
+Any alternate signal stack is not preserved
+.RB ( sigaltstack (2)).
+.IP \[bu]
+Memory mappings are not preserved
+.RB ( mmap (2)).
+.IP \[bu]
+Attached System\ V shared memory segments are detached
+.RB ( shmat (2)).
+.IP \[bu]
+POSIX shared memory regions are unmapped
+.RB ( shm_open (3)).
+.IP \[bu]
+Open POSIX message queue descriptors are closed
+.RB ( mq_overview (7)).
+.IP \[bu]
+Any open POSIX named semaphores are closed
+.RB ( sem_overview (7)).
+.IP \[bu]
+POSIX timers are not preserved
+.RB ( timer_create (2)).
+.IP \[bu]
+Any open directory streams are closed
+.RB ( opendir (3)).
+.IP \[bu]
+Memory locks are not preserved
+.RB ( mlock (2),
+.BR mlockall (2)).
+.IP \[bu]
+Exit handlers are not preserved
+.RB ( atexit (3),
+.BR on_exit (3)).
+.IP \[bu]
+The floating-point environment is reset to the default (see
+.BR fenv (3)).
+.P
+The process attributes in the preceding list are all specified
+in POSIX.1.
+The following Linux-specific process attributes are also
+not preserved during an
+.BR execve ():
+.IP \[bu] 3
+The process's "dumpable" attribute is set to the value 1,
+unless a set-user-ID program, a set-group-ID program,
+or a program with capabilities is being executed,
+in which case the dumpable flag may instead be reset to the value in
+.IR /proc/sys/fs/suid_dumpable ,
+in the circumstances described under
+.B PR_SET_DUMPABLE
+in
+.BR prctl (2).
+Note that changes to the "dumpable" attribute may cause ownership
+of files in the process's
+.IR /proc/ pid
+directory to change to
+.IR root:root ,
+as described in
+.BR proc (5).
+.IP \[bu]
+The
+.BR prctl (2)
+.B PR_SET_KEEPCAPS
+flag is cleared.
+.IP \[bu]
+(Since Linux 2.4.36 / 2.6.23)
+If a set-user-ID or set-group-ID program is being executed,
+then the parent death signal set by
+.BR prctl (2)
+.B PR_SET_PDEATHSIG
+flag is cleared.
+.IP \[bu]
+The process name, as set by
+.BR prctl (2)
+.B PR_SET_NAME
+(and displayed by
+.IR "ps\ \-o comm" ),
+is reset to the name of the new executable file.
+.IP \[bu]
+The
+.B SECBIT_KEEP_CAPS
+.I securebits
+flag is cleared.
+See
+.BR capabilities (7).
+.IP \[bu]
+The termination signal is reset to
+.B SIGCHLD
+(see
+.BR clone (2)).
+.IP \[bu]
+The file descriptor table is unshared, undoing the effect of the
+.B CLONE_FILES
+flag of
+.BR clone (2).
+.P
+Note the following further points:
+.IP \[bu] 3
+All threads other than the calling thread are destroyed during an
+.BR execve ().
+Mutexes, condition variables, and other pthreads objects are not preserved.
+.IP \[bu]
+The equivalent of \fIsetlocale(LC_ALL, "C")\fP
+is executed at program start-up.
+.IP \[bu]
+POSIX.1 specifies that the dispositions of any signals that
+are ignored or set to the default are left unchanged.
+POSIX.1 specifies one exception: if
+.B SIGCHLD
+is being ignored,
+then an implementation may leave the disposition unchanged or
+reset it to the default; Linux does the former.
+.IP \[bu]
+Any outstanding asynchronous I/O operations are canceled
+.RB ( aio_read (3),
+.BR aio_write (3)).
+.IP \[bu]
+For the handling of capabilities during
+.BR execve (),
+see
+.BR capabilities (7).
+.IP \[bu]
+By default, file descriptors remain open across an
+.BR execve ().
+File descriptors that are marked close-on-exec are closed;
+see the description of
+.B FD_CLOEXEC
+in
+.BR fcntl (2).
+(If a file descriptor is closed, this will cause the release
+of all record locks obtained on the underlying file by this process.
+See
+.BR fcntl (2)
+for details.)
+POSIX.1 says that if file descriptors 0, 1, and 2 would
+otherwise be closed after a successful
+.BR execve (),
+and the process would gain privilege because the set-user-ID or
+set-group-ID mode bit was set on the executed file,
+then the system may open an unspecified file for each of these
+file descriptors.
+As a general principle, no portable program, whether privileged or not,
+can assume that these three file descriptors will remain
+closed across an
+.BR execve ().
+.\" On Linux it appears that these file descriptors are
+.\" always open after an execve(), and it looks like
+.\" Solaris 8 and FreeBSD 6.1 are the same. -- mtk, 30 Apr 2007
+.SS Interpreter scripts
+An interpreter script is a text file that has execute
+permission enabled and whose first line is of the form:
+.P
+.in +4n
+.EX
+\fB#!\fP\fIinterpreter \fP[optional-arg]
+.EE
+.in
+.P
+The
+.I interpreter
+must be a valid pathname for an executable file.
+.P
+If the
+.I pathname
+argument of
+.BR execve ()
+specifies an interpreter script, then
+.I interpreter
+will be invoked with the following arguments:
+.P
+.in +4n
+.EX
+\fIinterpreter\fP [optional-arg] \fIpathname\fP arg...
+.EE
+.in
+.P
+where
+.I pathname
+is the pathname of the file specified as the first argument of
+.BR execve (),
+and
+.I arg...
+is the series of words pointed to by the
+.I argv
+argument of
+.BR execve (),
+starting at
+.IR argv[1] .
+Note that there is no way to get the
+.I argv[0]
+that was passed to the
+.BR execve ()
+call.
+.\" See the P - preserve-argv[0] option.
+.\" Documentation/admin-guide/binfmt-misc.rst
+.\" https://www.kernel.org/doc/html/latest/admin-guide/binfmt-misc.html
+.P
+For portable use,
+.I optional-arg
+should either be absent, or be specified as a single word (i.e., it
+should not contain white space); see NOTES below.
+.P
+Since Linux 2.6.28,
+.\" commit bf2a9a39639b8b51377905397a5005f444e9a892
+the kernel permits the interpreter of a script to itself be a script.
+This permission is recursive, up to a limit of four recursions,
+so that the interpreter may be a script which is interpreted by a script,
+and so on.
+.SS Limits on size of arguments and environment
+Most UNIX implementations impose some limit on the total size
+of the command-line argument
+.RI ( argv )
+and environment
+.RI ( envp )
+strings that may be passed to a new program.
+POSIX.1 allows an implementation to advertise this limit using the
+.B ARG_MAX
+constant (either defined in
+.I <limits.h>
+or available at run time using the call
+.IR "sysconf(_SC_ARG_MAX)" ).
+.P
+Before Linux 2.6.23, the memory used to store the
+environment and argument strings was limited to 32 pages
+(defined by the kernel constant
+.BR MAX_ARG_PAGES ).
+On architectures with a 4-kB page size,
+this yields a maximum size of 128\ kB.
+.P
+On Linux 2.6.23 and later, most architectures support a size limit
+derived from the soft
+.B RLIMIT_STACK
+resource limit (see
+.BR getrlimit (2))
+that is in force at the time of the
+.BR execve ()
+call.
+(Architectures with no memory management unit are excepted:
+they maintain the limit that was in effect before Linux 2.6.23.)
+This change allows programs to have a much larger
+argument and/or environment list.
+.\" For some background on the changes to ARG_MAX in Linux 2.6.23 and
+.\" Linux 2.6.25, see:
+.\"     http://sourceware.org/bugzilla/show_bug.cgi?id=5786
+.\"     http://bugzilla.kernel.org/show_bug.cgi?id=10095
+.\"     http://thread.gmane.org/gmane.linux.kernel/646709/focus=648101,
+.\"     checked into Linux 2.6.25 as commit a64e715fc74b1a7dcc5944f848acc38b2c4d4ee2.
+For these architectures, the total size is limited to 1/4 of the allowed
+stack size.
+(Imposing the 1/4-limit
+ensures that the new program always has some stack space.)
+.\" Ollie: That doesn't include the lists of pointers, though,
+.\" so the actual usage is a bit higher (1 pointer per argument).
+Additionally, the total size is limited to 3/4 of the value
+of the kernel constant
+.B _STK_LIM
+(8 MiB).
+Since Linux 2.6.25,
+the kernel also places a floor of 32 pages on this size limit,
+so that, even when
+.B RLIMIT_STACK
+is set very low,
+applications are guaranteed to have at least as much argument and
+environment space as was provided by Linux 2.6.22 and earlier.
+(This guarantee was not provided in Linux 2.6.23 and 2.6.24.)
+Additionally, the limit per string is 32 pages (the kernel constant
+.BR MAX_ARG_STRLEN ),
+and the maximum number of strings is 0x7FFFFFFF.
+.SH RETURN VALUE
+On success,
+.BR execve ()
+does not return, on error \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B E2BIG
+The total number of bytes in the environment
+.RI ( envp )
+and argument list
+.RI ( argv )
+is too large,
+an argument or environment string is too long,
+or the full
+.I pathname
+of the executable is too long.
+The terminating null byte is counted as part of the string length.
+.TP
+.B EACCES
+Search permission is denied on a component of the path prefix of
+.I pathname
+or the name of a script interpreter.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EACCES
+The file or a script interpreter is not a regular file.
+.TP
+.B EACCES
+Execute permission is denied for the file or a script or ELF interpreter.
+.TP
+.B EACCES
+The filesystem is mounted
+.IR noexec .
+.TP
+.BR EAGAIN " (since Linux 3.1)"
+.\" commit 72fa59970f8698023045ab0713d66f3f4f96945c
+Having changed its real UID using one of the
+.BR set*uid ()
+calls, the caller was\[em]and is now still\[em]above its
+.B RLIMIT_NPROC
+resource limit (see
+.BR setrlimit (2)).
+For a more detailed explanation of this error, see NOTES.
+.TP
+.B EFAULT
+.I pathname
+or one of the pointers in the vectors
+.I argv
+or
+.I envp
+points outside your accessible address space.
+.TP
+.B EINVAL
+An ELF executable had more than one PT_INTERP segment (i.e., tried to
+name more than one interpreter).
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B EISDIR
+An ELF interpreter was a directory.
+.TP
+.B ELIBBAD
+An ELF interpreter was not in a recognized format.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.I pathname
+or the name of a script or ELF interpreter.
+.TP
+.B ELOOP
+The maximum recursion limit was reached during recursive script
+interpretation (see "Interpreter scripts", above).
+Before Linux 3.8,
+.\" commit d740269867021faf4ce38a449353d2b986c34a67
+the error produced for this case was
+.BR ENOEXEC .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+The file
+.I pathname
+or a script or ELF interpreter does not exist.
+.TP
+.B ENOEXEC
+An executable is not in a recognized format, is for the wrong
+architecture, or has some other format error that means it cannot be
+executed.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of the path prefix of
+.I pathname
+or a script or ELF interpreter is not a directory.
+.TP
+.B EPERM
+The filesystem is mounted
+.IR nosuid ,
+the user is not the superuser,
+and the file has the set-user-ID or set-group-ID bit set.
+.TP
+.B EPERM
+The process is being traced, the user is not the superuser and the
+file has the set-user-ID or set-group-ID bit set.
+.TP
+.B EPERM
+A "capability-dumb" applications would not obtain the full set of
+permitted capabilities granted by the executable file.
+See
+.BR capabilities (7).
+.TP
+.B ETXTBSY
+The specified executable was open for writing by one or more processes.
+.SH VERSIONS
+POSIX does not document the #! behavior, but it exists
+(with some variations) on other UNIX systems.
+.P
+On Linux,
+.I argv
+and
+.I envp
+can be specified as NULL.
+In both cases, this has the same effect as specifying the argument
+as a pointer to a list containing a single null pointer.
+.B "Do not take advantage of this nonstandard and nonportable misfeature!"
+On many other UNIX systems, specifying
+.I argv
+as NULL will result in an error
+.RB ( EFAULT ).
+.I Some
+other UNIX systems treat the
+.I envp==NULL
+case the same as Linux.
+.\" e.g., EFAULT on Solaris 8 and FreeBSD 6.1; but
+.\" HP-UX 11 is like Linux -- mtk, Apr 2007
+.\" Bug filed 30 Apr 2007: http://bugzilla.kernel.org/show_bug.cgi?id=8408
+.\" Bug rejected (because fix would constitute an ABI change).
+.\"
+.P
+POSIX.1 says that values returned by
+.BR sysconf (3)
+should be invariant over the lifetime of a process.
+However, since Linux 2.6.23, if the
+.B RLIMIT_STACK
+resource limit changes, then the value reported by
+.B _SC_ARG_MAX
+will also change,
+to reflect the fact that the limit on space for holding
+command-line arguments and environment variables has changed.
+.\"
+.SS Interpreter scripts
+The kernel imposes a maximum length on the text that follows the
+"#!" characters at the start of a script;
+characters beyond the limit are ignored.
+Before Linux 5.1, the limit is 127 characters.
+Since Linux 5.1,
+.\" commit 6eb3c3d0a52dca337e327ae8868ca1f44a712e02
+the limit is 255 characters.
+.P
+The semantics of the
+.I optional-arg
+argument of an interpreter script vary across implementations.
+On Linux, the entire string following the
+.I interpreter
+name is passed as a single argument to the interpreter,
+and this string can include white space.
+However, behavior differs on some other systems.
+Some systems
+.\" e.g., Solaris 8
+use the first white space to terminate
+.IR optional-arg .
+On some systems,
+.\" e.g., FreeBSD before 6.0, but not FreeBSD 6.0 onward
+an interpreter script can have multiple arguments,
+and white spaces in
+.I optional-arg
+are used to delimit the arguments.
+.P
+Linux (like most other modern UNIX systems)
+ignores the set-user-ID and set-group-ID bits on scripts.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.\" SVr4 documents additional error
+.\" conditions EAGAIN, EINTR, ELIBACC, ENOLINK, EMULTIHOP; POSIX does not
+.\" document ETXTBSY, EPERM, EFAULT, ELOOP, EIO, ENFILE, EMFILE, EINVAL,
+.\" EISDIR or ELIBBAD error conditions.
+.P
+With UNIX\ V6, the argument list of an
+.BR exec ()
+call was ended by 0,
+while the argument list of
+.I main
+was ended by \-1.
+Thus, this argument list was not directly usable in a further
+.BR exec ()
+call.
+Since UNIX\ V7, both are NULL.
+.SH NOTES
+One sometimes sees
+.BR execve ()
+(and the related functions described in
+.BR exec (3))
+described as "executing a
+.I new
+process" (or similar).
+This is a highly misleading description:
+there is no new process;
+many attributes of the calling process remain unchanged
+(in particular, its PID).
+All that
+.BR execve ()
+does is arrange for an existing process (the calling process)
+to execute a new program.
+.P
+Set-user-ID and set-group-ID processes can not be
+.BR ptrace (2)d.
+.P
+The result of mounting a filesystem
+.I nosuid
+varies across Linux kernel versions:
+some will refuse execution of set-user-ID and set-group-ID
+executables when this would
+give the user powers they did not have already (and return
+.BR EPERM ),
+some will just ignore the set-user-ID and set-group-ID bits and
+.BR exec ()
+successfully.
+.P
+In most cases where
+.BR execve ()
+fails, control returns to the original executable image,
+and the caller of
+.BR execve ()
+can then handle the error.
+However, in (rare) cases (typically caused by resource exhaustion),
+failure may occur past the point of no return:
+the original executable image has been torn down,
+but the new image could not be completely built.
+In such cases, the kernel kills the process with a
+.\" commit 19d860a140beac48a1377f179e693abe86a9dac9
+.B SIGSEGV
+.RB ( SIGKILL
+until Linux 3.17)
+signal.
+.SS execve() and EAGAIN
+A more detailed explanation of the
+.B EAGAIN
+error that can occur (since Linux 3.1) when calling
+.BR execve ()
+is as follows.
+.P
+The
+.B EAGAIN
+error can occur when a
+.I preceding
+call to
+.BR setuid (2),
+.BR setreuid (2),
+or
+.BR setresuid (2)
+caused the real user ID of the process to change,
+and that change caused the process to exceed its
+.B RLIMIT_NPROC
+resource limit (i.e., the number of processes belonging
+to the new real UID exceeds the resource limit).
+From Linux 2.6.0 to Linux 3.0, this caused the
+.BR set*uid ()
+call to fail.
+(Before Linux 2.6,
+.\" commit 909cc4ae86f3380152a18e2a3c44523893ee11c4
+the resource limit was not imposed on processes that
+changed their user IDs.)
+.P
+Since Linux 3.1, the scenario just described no longer causes the
+.BR set*uid ()
+call to fail,
+because it too often led to security holes where buggy applications
+didn't check the return status and assumed
+that\[em]if the caller had root privileges\[em]the call would always succeed.
+Instead, the
+.BR set*uid ()
+calls now successfully change the real UID,
+but the kernel sets an internal flag, named
+.BR PF_NPROC_EXCEEDED ,
+to note that the
+.B RLIMIT_NPROC
+resource limit has been exceeded.
+If the
+.B PF_NPROC_EXCEEDED
+flag is set and the resource limit is still
+exceeded at the time of a subsequent
+.BR execve ()
+call, that call fails with the error
+.BR EAGAIN .
+This kernel logic ensures that the
+.B RLIMIT_NPROC
+resource limit is still enforced for the
+common privileged daemon workflow\[em]namely,
+.BR fork (2)
++
+.BR set*uid ()
++
+.BR execve ().
+.P
+If the resource limit was not still exceeded at the time of the
+.BR execve ()
+call
+(because other processes belonging to this real UID terminated between the
+.BR set*uid ()
+call and the
+.BR execve ()
+call), then the
+.BR execve ()
+call succeeds and the kernel clears the
+.B PF_NPROC_EXCEEDED
+process flag.
+The flag is also cleared if a subsequent call to
+.BR fork (2)
+by this process succeeds.
+.\"
+.\" .SH BUGS
+.\" Some Linux versions have failed to check permissions on ELF
+.\" interpreters.  This is a security hole, because it allows users to
+.\" open any file, such as a rewinding tape device, for reading.  Some
+.\" Linux versions have also had other security holes in
+.\" .BR execve ()
+.\" that could be exploited for denial of service by a suitably crafted
+.\" ELF binary.  There are no known problems with Linux 2.0.34 or Linux 2.2.15.
+.SH EXAMPLES
+The following program is designed to be execed by the second program below.
+It just echoes its command-line arguments, one per line.
+.P
+.in +4n
+.\" SRC BEGIN (myecho.c)
+.EX
+/* myecho.c */
+\&
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    for (size_t j = 0; j < argc; j++)
+        printf("argv[%zu]: %s\en", j, argv[j]);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.P
+This program can be used to exec the program named in its command-line
+argument:
+.P
+.in +4n
+.\" SRC BEGIN (execve.c)
+.EX
+/* execve.c */
+\&
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    static char *newargv[] = { NULL, "hello", "world", NULL };
+    static char *newenviron[] = { NULL };
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file\-to\-exec>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    newargv[0] = argv[1];
+\&
+    execve(argv[1], newargv, newenviron);
+    perror("execve");   /* execve() returns only on error */
+    exit(EXIT_FAILURE);
+}
+.EE
+.\" SRC END
+.in
+.P
+We can use the second program to exec the first as follows:
+.P
+.in +4n
+.EX
+.RB "$" " cc myecho.c \-o myecho"
+.RB "$" " cc execve.c \-o execve"
+.RB "$" " ./execve ./myecho"
+argv[0]: ./myecho
+argv[1]: hello
+argv[2]: world
+.EE
+.in
+.P
+We can also use these programs to demonstrate the use of a script
+interpreter.
+To do this we create a script whose "interpreter" is our
+.I myecho
+program:
+.P
+.in +4n
+.EX
+.RB "$" " cat > script"
+.B #!./myecho script\-arg
+.B \[ha]D
+.RB "$" " chmod +x script"
+.EE
+.in
+.P
+We can then use our program to exec the script:
+.P
+.in +4n
+.EX
+.RB "$" " ./execve ./script"
+argv[0]: ./myecho
+argv[1]: script\-arg
+argv[2]: ./script
+argv[3]: hello
+argv[4]: world
+.EE
+.in
+.SH SEE ALSO
+.BR chmod (2),
+.BR execveat (2),
+.BR fork (2),
+.BR get_robust_list (2),
+.BR ptrace (2),
+.BR exec (3),
+.BR fexecve (3),
+.BR getauxval (3),
+.BR getopt (3),
+.BR system (3),
+.BR capabilities (7),
+.BR credentials (7),
+.BR environ (7),
+.BR path_resolution (7),
+.BR ld.so (8)
diff --git a/man/man2/execveat.2 b/man/man2/execveat.2
new file mode 100644
index 000000000..ff0eb278f
--- /dev/null
+++ b/man/man2/execveat.2
@@ -0,0 +1,220 @@
+.\" Copyright (c) 2014 Google, Inc., written by David Drysdale
+.\" and Copyright (c) 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH execveat 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+execveat \- execute program relative to a directory file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fcntl.h>" "      /* Definition of " AT_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int execveat(int " dirfd ", const char *" pathname ,
+.BI "             char *const _Nullable " argv [],
+.BI "             char *const _Nullable " envp [],
+.BI "             int " flags );
+.fi
+.SH DESCRIPTION
+.\" commit 51f39a1f0cea1cacf8c787f652f26dfee9611874
+The
+.BR execveat ()
+system call executes the program referred to by the combination of
+.I dirfd
+and
+.IR pathname .
+It operates in exactly the same way as
+.BR execve (2),
+except for the differences described in this manual page.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR execve (2)
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR execve (2)).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+If
+.I pathname
+is an empty string and the
+.B AT_EMPTY_PATH
+flag is specified, then the file descriptor
+.I dirfd
+specifies the file to be executed (i.e.,
+.I dirfd
+refers to an executable file, rather than a directory).
+.P
+The
+.I flags
+argument is a bit mask that can include zero or more of the following flags:
+.TP
+.B AT_EMPTY_PATH
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.I dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If the file identified by
+.I dirfd
+and a non-NULL
+.I pathname
+is a symbolic link, then the call fails with the error
+.BR ELOOP .
+.SH RETURN VALUE
+On success,
+.BR execveat ()
+does not return.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The same errors that occur for
+.BR execve (2)
+can also occur for
+.BR execveat ().
+The following additional errors can occur for
+.BR execveat ():
+.TP
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EINVAL
+Invalid flag specified in
+.IR flags .
+.TP
+.B ELOOP
+.I flags
+includes
+.B AT_SYMLINK_NOFOLLOW
+and the file identified by
+.I dirfd
+and a non-NULL
+.I pathname
+is a symbolic link.
+.TP
+.B ENOENT
+The program identified by
+.I dirfd
+and
+.I pathname
+requires the use of an interpreter program
+(such as a script starting with "#!"), but the file descriptor
+.I dirfd
+was opened with the
+.B O_CLOEXEC
+flag, with the result that
+the program file is inaccessible to the launched interpreter.
+See BUGS.
+.TP
+.B ENOTDIR
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.19,
+glibc 2.34.
+.SH NOTES
+In addition to the reasons explained in
+.BR openat (2),
+the
+.BR execveat ()
+system call is also needed to allow
+.BR fexecve (3)
+to be implemented on systems that do not have the
+.I /proc
+filesystem mounted.
+.P
+When asked to execute a script file, the
+.I argv[0]
+that is passed to the script interpreter is a string of the form
+.I /dev/fd/N
+or
+.IR /dev/fd/N/P ,
+where
+.I N
+is the number of the file descriptor passed via the
+.I dirfd
+argument.
+A string of the first form occurs when
+.B AT_EMPTY_PATH
+is employed.
+A string of the second form occurs when the script is specified via both
+.I dirfd
+and
+.IR pathname ;
+in this case,
+.I P
+is the value given in
+.IR pathname .
+.P
+For the same reasons described in
+.BR fexecve (3),
+the natural idiom when using
+.BR execveat ()
+is to set the close-on-exec flag on
+.IR dirfd .
+(But see BUGS.)
+.SH BUGS
+The
+.B ENOENT
+error described above means that it is not possible to set the
+close-on-exec flag on the file descriptor given to a call of the form:
+.P
+.in +4n
+.EX
+execveat(fd, "", argv, envp, AT_EMPTY_PATH);
+.EE
+.in
+.P
+However, the inability to set the close-on-exec flag means that a file
+descriptor referring to the script leaks through to the script itself.
+As well as wasting a file descriptor,
+this leakage can lead to file-descriptor exhaustion in scenarios
+where scripts recursively employ
+.BR execveat ().
+.\" For an example, see Michael Kerrisk's 2015-01-10 reply in this LKML
+.\" thread (http://thread.gmane.org/gmane.linux.kernel/1836105/focus=20229):
+.\"
+.\"     Subject: [PATCHv10 man-pages 5/5] execveat.2: initial man page.\"                        for execveat(2
+.\"     Date: Mon, 24 Nov 2014 11:53:59 +0000
+.SH SEE ALSO
+.BR execve (2),
+.BR openat (2),
+.BR fexecve (3)
diff --git a/man/man2/exit.2 b/man/man2/exit.2
new file mode 100644
index 000000000..9f9d2e763
--- /dev/null
+++ b/man/man2/exit.2
@@ -0,0 +1 @@
+.so man2/_exit.2
diff --git a/man/man2/exit_group.2 b/man/man2/exit_group.2
new file mode 100644
index 000000000..ac7cb4243
--- /dev/null
+++ b/man/man2/exit_group.2
@@ -0,0 +1,38 @@
+.\" Copyright (C) 2004 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH exit_group 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+exit_group \- exit all threads in a process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "       /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "[[noreturn]] void syscall(SYS_exit_group, int " status );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR exit_group (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+This system call terminates all threads
+in the calling process's thread group.
+.SH RETURN VALUE
+This system call does not return.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.35.
+.SH NOTES
+Since glibc 2.3, this is the system call invoked when the
+.BR _exit (2)
+wrapper function is called.
+.SH SEE ALSO
+.BR _exit (2)
diff --git a/man/man2/faccessat.2 b/man/man2/faccessat.2
new file mode 100644
index 000000000..9d4f76e5b
--- /dev/null
+++ b/man/man2/faccessat.2
@@ -0,0 +1 @@
+.so man2/access.2
diff --git a/man/man2/faccessat2.2 b/man/man2/faccessat2.2
new file mode 100644
index 000000000..9d4f76e5b
--- /dev/null
+++ b/man/man2/faccessat2.2
@@ -0,0 +1 @@
+.so man2/access.2
diff --git a/man/man2/fadvise64.2 b/man/man2/fadvise64.2
new file mode 100644
index 000000000..53f54a121
--- /dev/null
+++ b/man/man2/fadvise64.2
@@ -0,0 +1 @@
+.so man2/posix_fadvise.2
diff --git a/man/man2/fadvise64_64.2 b/man/man2/fadvise64_64.2
new file mode 100644
index 000000000..53f54a121
--- /dev/null
+++ b/man/man2/fadvise64_64.2
@@ -0,0 +1 @@
+.so man2/posix_fadvise.2
diff --git a/man/man2/fallocate.2 b/man/man2/fallocate.2
new file mode 100644
index 000000000..bb2bb0521
--- /dev/null
+++ b/man/man2/fallocate.2
@@ -0,0 +1,481 @@
+.\" Copyright (c) 2007 Silicon Graphics, Inc. All Rights Reserved
+.\" Written by Dave Chinner <dgc@sgi.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.\"
+.\" 2011-09-19: Added FALLOC_FL_PUNCH_HOLE
+.\" 2011-09-19: Substantial restructuring of the page
+.\"
+.TH fallocate 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fallocate \- manipulate file space
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <fcntl.h>
+.P
+.BI "int fallocate(int " fd ", int " mode ", off_t " offset \
+", off_t " len ");"
+.fi
+.SH DESCRIPTION
+This is a nonportable, Linux-specific system call.
+For the portable, POSIX.1-specified method of ensuring that space
+is allocated for a file, see
+.BR posix_fallocate (3).
+.P
+.BR fallocate ()
+allows the caller to directly manipulate the allocated disk space
+for the file referred to by
+.I fd
+for the byte range starting at
+.I offset
+and continuing for
+.I len
+bytes.
+.P
+The
+.I mode
+argument determines the operation to be performed on the given range.
+Details of the supported operations are given in the subsections below.
+.SS Allocating disk space
+The default operation (i.e.,
+.I mode
+is zero) of
+.BR fallocate ()
+allocates the disk space within the range specified by
+.I offset
+and
+.IR len .
+The file size (as reported by
+.BR stat (2))
+will be changed if
+.IR offset + len
+is greater than the file size.
+Any subregion within the range specified by
+.I offset
+and
+.I len
+that did not contain data before the call will be initialized to zero.
+This default behavior closely resembles the behavior of the
+.BR posix_fallocate (3)
+library function,
+and is intended as a method of optimally implementing that function.
+.P
+After a successful call, subsequent writes into the range specified by
+.I offset
+and
+.I len
+are guaranteed not to fail because of lack of disk space.
+.P
+If the
+.B FALLOC_FL_KEEP_SIZE
+flag is specified in
+.IR mode ,
+the behavior of the call is similar,
+but the file size will not be changed even if
+.IR offset + len
+is greater than the file size.
+Preallocating zeroed blocks beyond the end of the file in this manner
+is useful for optimizing append workloads.
+.P
+If the
+.B FALLOC_FL_UNSHARE_RANGE
+flag is specified in
+.IR mode ,
+shared file data extents will be made private to the file to guarantee
+that a subsequent write will not fail due to lack of space.
+Typically, this will be done by performing a copy-on-write operation on
+all shared data in the file.
+This flag may not be supported by all filesystems.
+.P
+Because allocation is done in block size chunks,
+.BR fallocate ()
+may allocate a larger range of disk space than was specified.
+.SS Deallocating file space
+Specifying the
+.B FALLOC_FL_PUNCH_HOLE
+flag (available since Linux 2.6.38) in
+.I mode
+deallocates space (i.e., creates a hole)
+in the byte range starting at
+.I offset
+and continuing for
+.I len
+bytes.
+Within the specified range, partial filesystem blocks are zeroed,
+and whole filesystem blocks are removed from the file.
+After a successful call,
+subsequent reads from this range will return zeros.
+.P
+The
+.B FALLOC_FL_PUNCH_HOLE
+flag must be ORed with
+.B FALLOC_FL_KEEP_SIZE
+in
+.IR mode ;
+in other words, even when punching off the end of the file, the file size
+(as reported by
+.BR stat (2))
+does not change.
+.P
+Not all filesystems support
+.BR FALLOC_FL_PUNCH_HOLE ;
+if a filesystem doesn't support the operation, an error is returned.
+The operation is supported on at least the following filesystems:
+.IP \[bu] 3
+XFS (since Linux 2.6.38)
+.IP \[bu]
+ext4 (since Linux 3.0)
+.\" commit a4bb6b64e39abc0e41ca077725f2a72c868e7622
+.IP \[bu]
+Btrfs (since Linux 3.7)
+.IP \[bu]
+.BR tmpfs (5)
+(since Linux 3.5)
+.\" commit 83e4fa9c16e4af7122e31be3eca5d57881d236fe
+.IP \[bu]
+.BR gfs2 (5)
+(since Linux 4.16)
+.\" commit 4e56a6411fbce6f859566e17298114c2434391a4
+.SS Collapsing file space
+.\" commit 00f5e61998dd17f5375d9dfc01331f104b83f841
+Specifying the
+.B FALLOC_FL_COLLAPSE_RANGE
+flag (available since Linux 3.15) in
+.I mode
+removes a byte range from a file, without leaving a hole.
+The byte range to be collapsed starts at
+.I offset
+and continues for
+.I len
+bytes.
+At the completion of the operation,
+the contents of the file starting at the location
+.I offset+len
+will be appended at the location
+.IR offset ,
+and the file will be
+.I len
+bytes smaller.
+.P
+A filesystem may place limitations on the granularity of the operation,
+in order to ensure efficient implementation.
+Typically,
+.I offset
+and
+.I len
+must be a multiple of the filesystem logical block size,
+which varies according to the filesystem type and configuration.
+If a filesystem has such a requirement,
+.BR fallocate ()
+fails with the error
+.B EINVAL
+if this requirement is violated.
+.P
+If the region specified by
+.I offset
+plus
+.I len
+reaches or passes the end of file, an error is returned;
+instead, use
+.BR ftruncate (2)
+to truncate a file.
+.P
+No other flags may be specified in
+.I mode
+in conjunction with
+.BR FALLOC_FL_COLLAPSE_RANGE .
+.P
+As at Linux 3.15,
+.B FALLOC_FL_COLLAPSE_RANGE
+is supported by
+ext4 (only for extent-based files)
+.\" commit 9eb79482a97152930b113b51dff530aba9e28c8e
+and XFS.
+.\" commit e1d8fb88a64c1f8094b9f6c3b6d2d9e6719c970d
+.SS Zeroing file space
+Specifying the
+.B FALLOC_FL_ZERO_RANGE
+flag (available since Linux 3.15)
+.\" commit 409332b65d3ed8cfa7a8030f1e9d52f372219642
+in
+.I mode
+zeros space in the byte range starting at
+.I offset
+and continuing for
+.I len
+bytes.
+Within the specified range, blocks are preallocated for the regions
+that span the holes in the file.
+After a successful call, subsequent
+reads from this range will return zeros.
+.P
+Zeroing is done within the filesystem preferably by converting the range into
+unwritten extents.
+This approach means that the specified range will not be physically zeroed
+out on the device (except for partial blocks at the either end of the range),
+and I/O is (otherwise) required only to update metadata.
+.P
+If the
+.B FALLOC_FL_KEEP_SIZE
+flag is additionally specified in
+.IR mode ,
+the behavior of the call is similar,
+but the file size will not be changed even if
+.IR offset + len
+is greater than the file size.
+This behavior is the same as when preallocating space with
+.B FALLOC_FL_KEEP_SIZE
+specified.
+.P
+Not all filesystems support
+.BR FALLOC_FL_ZERO_RANGE ;
+if a filesystem doesn't support the operation, an error is returned.
+The operation is supported on at least the following filesystems:
+.IP \[bu] 3
+XFS (since Linux 3.15)
+.\" commit 376ba313147b4172f3e8cf620b9fb591f3e8cdfa
+.IP \[bu]
+ext4, for extent-based files (since Linux 3.15)
+.\" commit b8a8684502a0fc852afa0056c6bb2a9273f6fcc0
+.IP \[bu]
+SMB3 (since Linux 3.17)
+.\" commit 30175628bf7f521e9ee31ac98fa6d6fe7441a556
+.IP \[bu]
+Btrfs (since Linux 4.16)
+.\" commit f27451f229966874a8793995b8e6b74326d125df
+.SS Increasing file space
+Specifying the
+.B FALLOC_FL_INSERT_RANGE
+flag
+(available since Linux 4.1)
+.\" commit dd46c787788d5bf5b974729d43e4c405814a4c7d
+in
+.I mode
+increases the file space by inserting a hole within the file size without
+overwriting any existing data.
+The hole will start at
+.I offset
+and continue for
+.I len
+bytes.
+When inserting the hole inside file, the contents of the file starting at
+.I offset
+will be shifted upward (i.e., to a higher file offset) by
+.I len
+bytes.
+Inserting a hole inside a file increases the file size by
+.I len
+bytes.
+.P
+This mode has the same limitations as
+.B FALLOC_FL_COLLAPSE_RANGE
+regarding the granularity of the operation.
+If the granularity requirements are not met,
+.BR fallocate ()
+fails with the error
+.BR EINVAL .
+If the
+.I offset
+is equal to or greater than the end of file, an error is returned.
+For such operations (i.e., inserting a hole at the end of file),
+.BR ftruncate (2)
+should be used.
+.P
+No other flags may be specified in
+.I mode
+in conjunction with
+.BR FALLOC_FL_INSERT_RANGE .
+.P
+.B FALLOC_FL_INSERT_RANGE
+requires filesystem support.
+Filesystems that support this operation include
+XFS (since Linux 4.1)
+.\" commit a904b1ca5751faf5ece8600e18cd3b674afcca1b
+and ext4 (since Linux 4.2).
+.\" commit 331573febb6a224bc50322e3670da326cb7f4cfc
+.\" f2fs also has support since Linux 4.2
+.\"     commit f62185d0e283e9d311e3ac1020f159d95f0aab39
+.SH RETURN VALUE
+On success,
+.BR fallocate ()
+returns zero.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor, or is not opened for writing.
+.TP
+.B EFBIG
+.IR offset + len
+exceeds the maximum file size.
+.TP
+.B EFBIG
+.I mode
+is
+.BR FALLOC_FL_INSERT_RANGE ,
+and the current file size+\fIlen\fP exceeds the maximum file size.
+.TP
+.B EINTR
+A signal was caught during execution; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I offset
+was less than 0, or
+.I len
+.\" FIXME . (raise a kernel bug) Probably the len==0 case should be
+.\" a no-op, rather than an error. That would be consistent with
+.\" similar APIs for the len==0 case.
+.\" See "Re: [PATCH] fallocate.2: add FALLOC_FL_PUNCH_HOLE flag definition"
+.\" 21 Sep 2012
+.\" http://thread.gmane.org/gmane.linux.file-systems/48331/focus=1193526
+was less than or equal to 0.
+.TP
+.B EINVAL
+.I mode
+is
+.B FALLOC_FL_COLLAPSE_RANGE
+and the range specified by
+.I offset
+plus
+.I len
+reaches or passes the end of the file.
+.TP
+.B EINVAL
+.I mode
+is
+.B FALLOC_FL_INSERT_RANGE
+and the range specified by
+.I offset
+reaches or passes the end of the file.
+.TP
+.B EINVAL
+.I mode
+is
+.B FALLOC_FL_COLLAPSE_RANGE
+or
+.BR FALLOC_FL_INSERT_RANGE ,
+but either
+.I offset
+or
+.I len
+is not a multiple of the filesystem block size.
+.TP
+.B EINVAL
+.I mode
+contains one of
+.B FALLOC_FL_COLLAPSE_RANGE
+or
+.B FALLOC_FL_INSERT_RANGE
+and also other flags;
+no other flags are permitted with
+.B FALLOC_FL_COLLAPSE_RANGE
+or
+.BR FALLOC_FL_INSERT_RANGE .
+.TP
+.B EINVAL
+.I mode
+is
+.BR FALLOC_FL_COLLAPSE_RANGE ,
+.BR FALLOC_FL_ZERO_RANGE ,
+or
+.BR FALLOC_FL_INSERT_RANGE ,
+but the file referred to by
+.I fd
+is not a regular file.
+.\" There was an inconsistency in Linux 3.15-rc1, that should be resolved so that all
+.\" filesystems use this error for this case. (Tytso says ex4 will change.)
+.\" http://thread.gmane.org/gmane.comp.file-systems.xfs.general/60485/focus=5521
+.\" From: Michael Kerrisk (man-pages <mtk.manpages@...>
+.\" Subject: Re: [PATCH v5 10/10] manpage: update FALLOC_FL_COLLAPSE_RANGE flag in fallocate
+.\" Newsgroups: gmane.linux.man, gmane.linux.file-systems
+.\" Date: 2014-04-17 13:40:05 GMT
+.TP
+.B EIO
+An I/O error occurred while reading from or writing to a filesystem.
+.TP
+.B ENODEV
+.I fd
+does not refer to a regular file or a directory.
+(If
+.I fd
+is a pipe or FIFO, a different error results.)
+.TP
+.B ENOSPC
+There is not enough space left on the device containing the file
+referred to by
+.IR fd .
+.TP
+.B ENOSYS
+This kernel does not implement
+.BR fallocate ().
+.TP
+.B EOPNOTSUPP
+The filesystem containing the file referred to by
+.I fd
+does not support this operation;
+or the
+.I mode
+is not supported by the filesystem containing the file referred to by
+.IR fd .
+.TP
+.B EPERM
+The file referred to by
+.I fd
+is marked immutable (see
+.BR chattr (1)).
+.TP
+.B EPERM
+.I mode
+specifies
+.BR FALLOC_FL_PUNCH_HOLE ,
+.BR FALLOC_FL_COLLAPSE_RANGE ,
+or
+.B FALLOC_FL_INSERT_RANGE
+and
+the file referred to by
+.I fd
+is marked append-only
+(see
+.BR chattr (1)).
+.TP
+.B EPERM
+The operation was prevented by a file seal; see
+.BR fcntl (2).
+.TP
+.B ESPIPE
+.I fd
+refers to a pipe or FIFO.
+.TP
+.B ETXTBSY
+.I mode
+specifies
+.B FALLOC_FL_COLLAPSE_RANGE
+or
+.BR FALLOC_FL_INSERT_RANGE ,
+but the file referred to by
+.I fd
+is currently being executed.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR fallocate ()
+Linux 2.6.23,
+glibc 2.10.
+.TP
+.B FALLOC_FL_*
+glibc 2.18.
+.\" See http://sourceware.org/bugzilla/show_bug.cgi?id=14964
+.SH SEE ALSO
+.BR fallocate (1),
+.BR ftruncate (2),
+.BR posix_fadvise (3),
+.BR posix_fallocate (3)
diff --git a/man/man2/fanotify_init.2 b/man/man2/fanotify_init.2
new file mode 100644
index 000000000..e5f9cbf29
--- /dev/null
+++ b/man/man2/fanotify_init.2
@@ -0,0 +1,542 @@
+.\" Copyright (C) 2013, Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH fanotify_init 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fanotify_init \- create and initialize fanotify group
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" "            /* Definition of " O_* " constants */"
+.B #include <sys/fanotify.h>
+.P
+.BI "int fanotify_init(unsigned int " flags ", unsigned int " event_f_flags );
+.fi
+.SH DESCRIPTION
+For an overview of the fanotify API, see
+.BR fanotify (7).
+.P
+.BR fanotify_init ()
+initializes a new fanotify group and returns a file descriptor for the event
+queue associated with the group.
+.P
+The file descriptor is used in calls to
+.BR fanotify_mark (2)
+to specify the files, directories, mounts, or filesystems for which fanotify
+events shall be created.
+These events are received by reading from the file descriptor.
+Some events are only informative, indicating that a file has been accessed.
+Other events can be used to determine whether
+another application is permitted to access a file or directory.
+Permission to access filesystem objects is granted by writing to the file
+descriptor.
+.P
+Multiple programs may be using the fanotify interface at the same time to
+monitor the same files.
+.P
+The number of fanotify groups per user is limited.
+See
+.BR fanotify (7)
+for details about this limit.
+.P
+The
+.I flags
+argument contains a multi-bit field defining the notification class of the
+listening application and further single bit fields specifying the behavior
+of the file descriptor.
+.P
+If multiple listeners for permission events exist,
+the notification class is used to establish the sequence
+in which the listeners receive the events.
+.P
+Only one of the following notification classes may be specified in
+.IR flags :
+.TP
+.B FAN_CLASS_PRE_CONTENT
+This value allows the receipt of events notifying that a file has been
+accessed and events for permission decisions if a file may be accessed.
+It is intended for event listeners that need to access files before they
+contain their final data.
+This notification class might be used by hierarchical storage managers,
+for example.
+Use of this flag requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B FAN_CLASS_CONTENT
+This value allows the receipt of events notifying that a file has been
+accessed and events for permission decisions if a file may be accessed.
+It is intended for event listeners that need to access files when they
+already contain their final content.
+This notification class might be used by malware detection programs, for
+example.
+Use of this flag requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B FAN_CLASS_NOTIF
+This is the default value.
+It does not need to be specified.
+This value only allows the receipt of events notifying that a file has been
+accessed.
+Permission decisions before the file is accessed are not possible.
+.P
+Listeners with different notification classes will receive events in the
+order
+.BR FAN_CLASS_PRE_CONTENT ,
+.BR FAN_CLASS_CONTENT ,
+.BR FAN_CLASS_NOTIF .
+The order of notification for listeners in the same notification class
+is undefined.
+.P
+The following bits can additionally be set in
+.IR flags :
+.TP
+.B FAN_CLOEXEC
+Set the close-on-exec flag
+.RB ( FD_CLOEXEC )
+on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2).
+.TP
+.B FAN_NONBLOCK
+Enable the nonblocking flag
+.RB ( O_NONBLOCK )
+for the file descriptor.
+Reading from the file descriptor will not block.
+Instead, if no data is available,
+.BR read (2)
+fails with the error
+.BR EAGAIN .
+.TP
+.B FAN_UNLIMITED_QUEUE
+Remove the limit on the number of events in the event queue.
+See
+.BR fanotify (7)
+for details about this limit.
+Use of this flag requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B FAN_UNLIMITED_MARKS
+Remove the limit on the number of fanotify marks per user.
+See
+.BR fanotify (7)
+for details about this limit.
+Use of this flag requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR FAN_REPORT_TID " (since Linux 4.20)"
+.\" commit d0a6a87e40da49cfc7954c491d3065a25a641b29
+Report thread ID (TID) instead of process ID (PID)
+in the
+.I pid
+field of the
+.I "struct fanotify_event_metadata"
+supplied to
+.BR read (2)
+(see
+.BR fanotify (7)).
+Use of this flag requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR FAN_ENABLE_AUDIT " (since Linux 4.15)"
+.\" commit de8cd83e91bc3ee212b3e6ec6e4283af9e4ab269
+Enable generation of audit log records about access mediation performed by
+permission events.
+The permission event response has to be marked with the
+.B FAN_AUDIT
+flag for an audit log record to be generated.
+Use of this flag requires the
+.B CAP_AUDIT_WRITE
+capability.
+.TP
+.BR FAN_REPORT_FID " (since Linux 5.1)"
+.\" commit a8b13aa20afb69161b5123b4f1acc7ea0a03d360
+This value allows the receipt of events which contain additional information
+about the underlying filesystem object correlated to an event.
+An additional record of type
+.B FAN_EVENT_INFO_TYPE_FID
+encapsulates the information about the object and is included alongside the
+generic event metadata structure.
+The file descriptor that is used to represent the object correlated to an
+event is instead substituted with a file handle.
+It is intended for applications that may find the use of a file handle to
+identify an object more suitable than a file descriptor.
+Additionally, it may be used for applications monitoring a directory or a
+filesystem that are interested in the directory entry modification events
+.BR FAN_CREATE ,
+.BR FAN_DELETE ,
+.BR FAN_MOVE ,
+and
+.BR FAN_RENAME ,
+or in events such as
+.BR FAN_ATTRIB ,
+.BR FAN_DELETE_SELF ,
+and
+.BR FAN_MOVE_SELF .
+All the events above require an fanotify group that identifies filesystem
+objects by file handles.
+Note that without the flag
+.BR FAN_REPORT_TARGET_FID ,
+for the directory entry modification events,
+there is an information record that identifies the modified directory
+and not the created/deleted/moved child object.
+The use of
+.B FAN_CLASS_CONTENT
+or
+.B FAN_CLASS_PRE_CONTENT
+is not permitted with this flag and will result in the error
+.BR EINVAL .
+See
+.BR fanotify (7)
+for additional details.
+.TP
+.BR FAN_REPORT_DIR_FID " (since Linux 5.9)"
+.\" commit 83b7a59896dd24015a34b7f00027f0ff3747972f
+Events for fanotify groups initialized with this flag will contain
+(see exceptions below) additional information about a directory object
+correlated to an event.
+An additional record of type
+.B FAN_EVENT_INFO_TYPE_DFID
+encapsulates the information about the directory object and is included
+alongside the generic event metadata structure.
+For events that occur on a non-directory object, the additional structure
+includes a file handle that identifies the parent directory filesystem object.
+Note that there is no guarantee that the directory filesystem object will be
+found at the location described by the file handle information at the time
+the event is received.
+When combined with the flag
+.BR FAN_REPORT_FID ,
+two records may be reported with events that occur on a non-directory object,
+one to identify the non-directory object itself and one to identify the parent
+directory object.
+Note that in some cases, a filesystem object does not have a parent,
+for example, when an event occurs on an unlinked but open file.
+In that case, with the
+.B FAN_REPORT_FID
+flag, the event will be reported with only one record to identify the
+non-directory object itself, because there is no directory associated with
+the event.
+Without the
+.B FAN_REPORT_FID
+flag, no event will be reported.
+See
+.BR fanotify (7)
+for additional details.
+.TP
+.BR FAN_REPORT_NAME " (since Linux 5.9)"
+.\" commit 929943b38daf817f2e6d303ea04401651fc3bc05
+Events for fanotify groups initialized with this flag will contain additional
+information about the name of the directory entry correlated to an event.
+This flag must be provided in conjunction with the flag
+.BR FAN_REPORT_DIR_FID .
+Providing this flag value without
+.B FAN_REPORT_DIR_FID
+will result in the error
+.BR EINVAL .
+This flag may be combined with the flag
+.BR FAN_REPORT_FID .
+An additional record of type
+.BR FAN_EVENT_INFO_TYPE_DFID_NAME ,
+which encapsulates the information about the directory entry, is included
+alongside the generic event metadata structure and substitutes the additional
+information record of type
+.BR FAN_EVENT_INFO_TYPE_DFID .
+The additional record includes a file handle that identifies a directory
+filesystem object followed by a name that identifies an entry in that
+directory.
+For the directory entry modification events
+.BR FAN_CREATE ,
+.BR FAN_DELETE ,
+and
+.BR FAN_MOVE ,
+the reported name is that of the created/deleted/moved directory entry.
+The event
+.B FAN_RENAME
+may contain two information records.
+One of type
+.B FAN_EVENT_INFO_TYPE_OLD_DFID_NAME
+identifying the old directory entry,
+and another of type
+.B FAN_EVENT_INFO_TYPE_NEW_DFID_NAME
+identifying the new directory entry.
+For other events that occur on a directory object, the reported file handle
+is that of the directory object itself and the reported name is '.'.
+For other events that occur on a non-directory object, the reported file handle
+is that of the parent directory object and the reported name is the name of a
+directory entry where the object was located at the time of the event.
+The rationale behind this logic is that the reported directory file handle can
+be passed to
+.BR open_by_handle_at (2)
+to get an open directory file descriptor and that file descriptor along with
+the reported name can be used to call
+.BR fstatat (2).
+The same rule that applies to record type
+.B FAN_EVENT_INFO_TYPE_DFID
+also applies to record type
+.BR FAN_EVENT_INFO_TYPE_DFID_NAME :
+if a non-directory object has no parent, either the event will not be reported
+or it will be reported without the directory entry information.
+Note that there is no guarantee that the filesystem object will be found at the
+location described by the directory entry information at the time the event is
+received.
+See
+.BR fanotify (7)
+for additional details.
+.TP
+.B FAN_REPORT_DFID_NAME
+This is a synonym for
+.RB ( FAN_REPORT_DIR_FID | FAN_REPORT_NAME ).
+.TP
+.BR FAN_REPORT_TARGET_FID " (since Linux 5.17)"
+.\" commit d61fd650e9d206a71fda789f02a1ced4b19944c4
+Events for fanotify groups initialized with this flag
+will contain additional information about the child
+correlated with directory entry modification events.
+This flag must be provided in conjunction with the flags
+.BR FAN_REPORT_FID ,
+.B FAN_REPORT_DIR_FID
+and
+.BR FAN_REPORT_NAME .
+or else the error
+.B EINVAL
+will be returned.
+For the directory entry modification events
+.BR FAN_CREATE ,
+.BR FAN_DELETE ,
+.BR FAN_MOVE ,
+and
+.BR FAN_RENAME ,
+an additional record of type
+.BR FAN_EVENT_INFO_TYPE_FID ,
+is reported in addition to the information records of type
+.BR FAN_EVENT_INFO_TYPE_DFID ,
+.BR FAN_EVENT_INFO_TYPE_DFID_NAME ,
+.BR FAN_EVENT_INFO_TYPE_OLD_DFID_NAME ,
+and
+.BR FAN_EVENT_INFO_TYPE_NEW_DFID_NAME .
+The additional record includes a file handle
+that identifies the filesystem child object
+that the directory entry is referring to.
+.TP
+.B FAN_REPORT_DFID_NAME_TARGET
+This is a synonym for
+.RB ( FAN_REPORT_DFID_NAME | FAN_REPORT_FID | FAN_REPORT_TARGET_FID ).
+.TP
+.BR FAN_REPORT_PIDFD " (since Linux 5.15)"
+.\" commit af579beb666aefb17e9a335c12c788c92932baf1
+Events for fanotify groups initialized with this flag will contain
+an additional information record alongside the generic
+.I fanotify_event_metadata
+structure.
+This information record will be of type
+.B FAN_EVENT_INFO_TYPE_PIDFD
+and will contain a pidfd for the process that
+was responsible for generating an event.
+A pidfd returned in this information record object is
+no different to the pidfd that is returned when calling
+.BR pidfd_open (2).
+Usage of this information record are for applications that
+may be interested in reliably determining whether
+the process responsible for generating an event
+has been recycled or terminated.
+The use of the
+.B FAN_REPORT_TID
+flag along with
+.B FAN_REPORT_PIDFD
+is currently not supported and
+attempting to do so will result in the error
+.B EINVAL
+being returned.
+This limitation is currently imposed by the pidfd API
+as it currently only supports
+the creation of pidfds for thread-group leaders.
+Creating pidfds for non-thread-group leaders
+may be supported at some point in the future,
+so this restriction may eventually be lifted.
+For more details on information records,
+see
+.BR fanotify (7).
+.P
+The
+.I event_f_flags
+argument
+defines the file status flags that will be set on the open file descriptions
+that are created for fanotify events.
+For details of these flags, see the description of the
+.I flags
+values in
+.BR open (2).
+.I event_f_flags
+includes a multi-bit field for the access mode.
+This field can take the following values:
+.TP
+.B O_RDONLY
+This value allows only read access.
+.TP
+.B O_WRONLY
+This value allows only write access.
+.TP
+.B O_RDWR
+This value allows read and write access.
+.P
+Additional bits can be set in
+.IR event_f_flags .
+The most useful values are:
+.TP
+.B O_LARGEFILE
+Enable support for files exceeding 2\ GB.
+Failing to set this flag will result in an
+.B EOVERFLOW
+error when trying to open a large file which is monitored by
+an fanotify group on a 32-bit system.
+.TP
+.BR O_CLOEXEC " (since Linux 3.18)"
+.\" commit 0b37e097a648aa71d4db1ad108001e95b69a2da4
+Enable the close-on-exec flag for the file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.P
+The following are also allowable:
+.BR O_APPEND ,
+.BR O_DSYNC ,
+.BR O_NOATIME ,
+.BR O_NONBLOCK ,
+and
+.BR O_SYNC .
+Specifying any other flag in
+.I event_f_flags
+yields the error
+.B EINVAL
+(but see BUGS).
+.SH RETURN VALUE
+On success,
+.BR fanotify_init ()
+returns a new file descriptor.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+An invalid value was passed in
+.I flags
+or
+.IR event_f_flags .
+.B FAN_ALL_INIT_FLAGS
+(deprecated since Linux 4.20)
+.\" commit 23c9deeb3285d34fd243abb3d6b9f07db60c3cf4
+defines all allowable bits for
+.IR flags .
+.TP
+.B EMFILE
+The number of fanotify groups for this user exceeds the limit.
+See
+.BR fanotify (7)
+for details about this limit.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENOMEM
+The allocation of memory for the notification group failed.
+.TP
+.B ENOSYS
+This kernel does not implement
+.BR fanotify_init ().
+The fanotify API is available only if the kernel was configured with
+.BR CONFIG_FANOTIFY .
+.TP
+.B EPERM
+The operation is not permitted because the caller lacks a required capability.
+.SH VERSIONS
+Prior to Linux 5.13,
+.\" commit 7cea2a3c505e87a9d6afc78be4a7f7be636a73a7
+calling
+.BR fanotify_init ()
+required the
+.B CAP_SYS_ADMIN
+capability.
+Since Linux 5.13,
+.\" commit 7cea2a3c505e87a9d6afc78be4a7f7be636a73a7
+users may call
+.BR fanotify_init ()
+without the
+.B CAP_SYS_ADMIN
+capability to create and initialize
+an fanotify group with limited functionality.
+.TP
+The limitations imposed on an event listener created by a user without the
+.B CAP_SYS_ADMIN
+capability are as follows:
+.RS
+.IP \[bu] 3
+The user cannot request for an unlimited event queue by using
+.BR FAN_UNLIMITED_QUEUE .
+.IP \[bu]
+The user cannot request for an unlimited number of marks by using
+.BR FAN_UNLIMITED_MARKS .
+.IP \[bu]
+The user cannot request to use either notification classes
+.B FAN_CLASS_CONTENT
+or
+.BR FAN_CLASS_PRE_CONTENT .
+This means that user cannot request permission events.
+.IP \[bu]
+The user is required to create a group that identifies filesystem objects by
+file handles, for example, by providing the
+.B FAN_REPORT_FID
+flag.
+.IP \[bu]
+The user is limited to only mark inodes.
+The ability to mark a mount or filesystem via
+.BR fanotify_mark ()
+through the use of
+.B FAN_MARK_MOUNT
+or
+.B FAN_MARK_FILESYSTEM
+is not permitted.
+.IP \[bu]
+The event object in the event queue is limited in terms of the information
+that is made available to the unprivileged user.
+A user will also not receive the pid that generated the event, unless the
+listening process itself generated the event.
+.RE
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.37.
+.\" was introduced in Linux 2.6.36 and enabled in Linux 2.6.37.
+.SH BUGS
+The following bug was present before Linux 3.18:
+.IP \[bu] 3
+.\" Fixed by commit 0b37e097a648aa71d4db1ad108001e95b69a2da4
+The
+.B O_CLOEXEC
+is ignored when passed in
+.IR event_f_flags .
+.P
+The following bug was present before Linux 3.14:
+.IP \[bu] 3
+.\" Fixed by commit 48149e9d3a7e924010a0daab30a6197b7d7b6580
+The
+.I event_f_flags
+argument is not checked for invalid flags.
+Flags that are intended only for internal use,
+such as
+.BR FMODE_EXEC ,
+can be set, and will consequently be set for the file descriptors
+returned when reading from the fanotify file descriptor.
+.SH SEE ALSO
+.BR fanotify_mark (2),
+.BR fanotify (7)
diff --git a/man/man2/fanotify_mark.2 b/man/man2/fanotify_mark.2
new file mode 100644
index 000000000..f3fce0c4e
--- /dev/null
+++ b/man/man2/fanotify_mark.2
@@ -0,0 +1,850 @@
+.\" Copyright (C) 2013,  Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH fanotify_mark 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fanotify_mark \- add, remove, or modify an fanotify mark on a filesystem
+object
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/fanotify.h>
+.P
+.BI "int fanotify_mark(int " fanotify_fd ", unsigned int " flags ,
+.BI "                  uint64_t " mask ", int " dirfd ,
+.BI "                  const char *_Nullable " pathname );
+.fi
+.SH DESCRIPTION
+For an overview of the fanotify API, see
+.BR fanotify (7).
+.P
+.BR fanotify_mark ()
+adds, removes, or modifies an fanotify mark on a filesystem object.
+The caller must have read permission on the filesystem object that
+is to be marked.
+.P
+The
+.I fanotify_fd
+argument is a file descriptor returned by
+.BR fanotify_init (2).
+.P
+.I flags
+is a bit mask describing the modification to perform.
+It must include exactly one of the following values:
+.TP
+.B FAN_MARK_ADD
+The events in
+.I mask
+will be added to the mark mask (or to the ignore mask).
+.I mask
+must be nonempty or the error
+.B EINVAL
+will occur.
+.TP
+.B FAN_MARK_REMOVE
+The events in argument
+.I mask
+will be removed from the mark mask (or from the ignore mask).
+.I mask
+must be nonempty or the error
+.B EINVAL
+will occur.
+.TP
+.B FAN_MARK_FLUSH
+Remove either all marks for filesystems, all marks for mounts, or all
+marks for directories and files from the fanotify group.
+If
+.I flags
+contains
+.BR FAN_MARK_MOUNT ,
+all marks for mounts are removed from the group.
+If
+.I flags
+contains
+.BR FAN_MARK_FILESYSTEM ,
+all marks for filesystems are removed from the group.
+Otherwise, all marks for directories and files are removed.
+No flag other than, and at most one of, the flags
+.B FAN_MARK_MOUNT
+or
+.B FAN_MARK_FILESYSTEM
+can be used in conjunction with
+.BR FAN_MARK_FLUSH .
+.I mask
+is ignored.
+.P
+If none of the values above is specified, or more than one is specified,
+the call fails with the error
+.BR EINVAL .
+.P
+In addition,
+zero or more of the following values may be ORed into
+.IR flags :
+.TP
+.B FAN_MARK_DONT_FOLLOW
+If
+.I pathname
+is a symbolic link, mark the link itself, rather than the file to which it
+refers.
+(By default,
+.BR fanotify_mark ()
+dereferences
+.I pathname
+if it is a symbolic link.)
+.TP
+.B FAN_MARK_ONLYDIR
+If the filesystem object to be marked is not a directory, the error
+.B ENOTDIR
+shall be raised.
+.TP
+.B FAN_MARK_MOUNT
+Mark the mount specified by
+.IR pathname .
+If
+.I pathname
+is not itself a mount point, the mount containing
+.I pathname
+will be marked.
+All directories, subdirectories, and the contained files of the mount
+will be monitored.
+The events which require that filesystem objects are identified by file handles,
+such as
+.BR FAN_CREATE ,
+.BR FAN_ATTRIB ,
+.BR FAN_MOVE ,
+and
+.BR FAN_DELETE_SELF ,
+cannot be provided as a
+.I mask
+when
+.I flags
+contains
+.BR FAN_MARK_MOUNT .
+Attempting to do so will result in the error
+.B EINVAL
+being returned.
+Use of this flag requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR FAN_MARK_FILESYSTEM " (since Linux 4.20)"
+.\" commit d54f4fba889b205e9cd8239182ca5d27d0ac3bc2
+Mark the filesystem specified by
+.IR pathname .
+The filesystem containing
+.I pathname
+will be marked.
+All the contained files and directories of the filesystem from any mount
+point will be monitored.
+Use of this flag requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B FAN_MARK_IGNORED_MASK
+The events in
+.I mask
+shall be added to or removed from the ignore mask.
+Note that the flags
+.BR FAN_ONDIR ,
+and
+.B FAN_EVENT_ON_CHILD
+have no effect when provided with this flag.
+The effect of setting the flags
+.BR FAN_ONDIR ,
+and
+.B FAN_EVENT_ON_CHILD
+in the mark mask
+on the events that are set in the ignore mask
+is undefined and depends on the Linux kernel version.
+Specifically, prior to Linux 5.9,
+.\" commit 497b0c5a7c0688c1b100a9c2e267337f677c198e
+setting a mark mask on a file
+and a mark with ignore mask on its parent directory
+would not result in ignoring events on the file,
+regardless of the
+.B FAN_EVENT_ON_CHILD
+flag in the parent directory's mark mask.
+When the ignore mask is updated with the
+.B FAN_MARK_IGNORED_MASK
+flag
+on a mark that was previously updated with the
+.B FAN_MARK_IGNORE
+flag,
+the update fails with
+.B EEXIST
+error.
+.TP
+.BR FAN_MARK_IGNORE " (since Linux 6.0)"
+.\" commit e252f2ed1c8c6c3884ab5dd34e003ed21f1fe6e0
+This flag has a similar effect as setting the
+.B FAN_MARK_IGNORED_MASK
+flag.
+The events in
+.I mask
+shall be added to or removed from the ignore mask.
+Unlike the
+.B FAN_MARK_IGNORED_MASK
+flag,
+this flag also has the effect that the
+.BR FAN_ONDIR ,
+and
+.B FAN_EVENT_ON_CHILD
+flags take effect on the ignore mask.
+Specifically, unless the
+.B FAN_ONDIR
+flag is set with
+.BR FAN_MARK_IGNORE ,
+events on directories will not be ignored.
+If the flag
+.B FAN_EVENT_ON_CHILD
+is set with
+.BR FAN_MARK_IGNORE ,
+events on children will be ignored.
+For example,
+a mark on a directory with combination of
+a mask with
+.B FAN_CREATE
+event
+and
+.B FAN_ONDIR
+flag
+and an ignore mask with
+.B FAN_CREATE
+event
+and without
+.B FAN_ONDIR
+flag,
+will result in getting only
+the events for creation of sub-directories.
+When using the
+.B FAN_MARK_IGNORE
+flag to add to an ignore mask
+of a mount,
+filesystem,
+or directory inode mark,
+the
+.B FAN_MARK_IGNORED_SURV_MODIFY
+flag must be specified.
+Failure to do so will results with
+.B EINVAL
+or
+.B EISDIR
+error.
+.TP
+.B FAN_MARK_IGNORED_SURV_MODIFY
+The ignore mask shall survive modify events.
+If this flag is not set,
+the ignore mask is cleared when a modify event occurs
+on the marked object.
+Omitting this flag is typically used to suppress events
+(e.g.,
+.BR FAN_OPEN )
+for a specific file,
+until that specific file's content has been modified.
+It is far less useful to suppress events
+on an entire filesystem,
+or mount,
+or on all files inside a directory,
+until some file's content has been modified.
+For this reason,
+the
+.B FAN_MARK_IGNORE
+flag requires the
+.B FAN_MARK_IGNORED_SURV_MODIFY
+flag on a mount,
+filesystem,
+or directory inode mark.
+This flag cannot be removed from a mark once set.
+When the ignore mask is updated without this flag
+on a mark that was previously updated with the
+.B FAN_MARK_IGNORE
+and
+.B FAN_MARK_IGNORED_SURV_MODIFY
+flags,
+the update fails with
+.B EEXIST
+error.
+.TP
+.B FAN_MARK_IGNORE_SURV
+This is a synonym for
+.RB ( FAN_MARK_IGNORE | FAN_MARK_IGNORED_SURV_MODIFY ).
+.TP
+.BR FAN_MARK_EVICTABLE " (since Linux 5.19)"
+.\" commit 5f9d3bd520261fd7a850818c71809fd580e0f30c
+When an inode mark is created with this flag,
+the inode object will not be pinned to the inode cache,
+therefore,
+allowing the inode object to be evicted from the inode cache
+when the memory pressure on the system is high.
+The eviction of the inode object
+results in the evictable mark also being lost.
+When the mask of an evictable inode mark is updated
+without using the
+.B FAN_MARK_EVICATBLE
+flag,
+the marked inode is pinned to inode cache
+and the mark is no longer evictable.
+When the mask of a non-evictable inode mark is updated
+with the
+.B FAN_MARK_EVICTABLE
+flag,
+the inode mark remains non-evictable
+and the update fails with
+.B EEXIST
+error.
+Mounts and filesystems are not evictable objects,
+therefore,
+an attempt to create a mount mark or a filesystem mark
+with the
+.B FAN_MARK_EVICTABLE
+flag,
+will result in the error
+.BR EINVAL .
+For example,
+inode marks can be used in combination with mount marks
+to reduce the amount of events from noninteresting paths.
+The event listener reads events,
+checks if the path reported in the event is of interest,
+and if it is not,
+the listener sets a mark with an ignore mask on the directory.
+Evictable inode marks allow using this method for a large number of directories
+without the concern of pinning all inodes and exhausting the system's memory.
+.P
+.I mask
+defines which events shall be listened for (or which shall be ignored).
+It is a bit mask composed of the following values:
+.TP
+.B FAN_ACCESS
+Create an event when a file or directory (but see BUGS) is accessed (read).
+.TP
+.B FAN_MODIFY
+Create an event when a file is modified (write).
+.TP
+.B FAN_CLOSE_WRITE
+Create an event when a writable file is closed.
+.TP
+.B FAN_CLOSE_NOWRITE
+Create an event when a read-only file or directory is closed.
+.TP
+.B FAN_OPEN
+Create an event when a file or directory is opened.
+.TP
+.BR FAN_OPEN_EXEC " (since Linux 5.0)"
+.\" commit 9b076f1c0f4869b838a1b7aa0edb5664d47ec8aa
+Create an event when a file is opened with the intent to be executed.
+See NOTES for additional details.
+.TP
+.BR FAN_ATTRIB " (since Linux 5.1)"
+.\" commit 235328d1fa4251c6dcb32351219bb553a58838d2
+Create an event when the metadata for a file or directory has changed.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.TP
+.BR FAN_CREATE " (since Linux 5.1)"
+.\" commit 235328d1fa4251c6dcb32351219bb553a58838d2
+Create an event when a file or directory has been created in a marked
+parent directory.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.TP
+.BR FAN_DELETE " (since Linux 5.1)"
+.\" commit 235328d1fa4251c6dcb32351219bb553a58838d2
+Create an event when a file or directory has been deleted in a marked
+parent directory.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.TP
+.BR FAN_DELETE_SELF " (since Linux 5.1)"
+.\" commit 235328d1fa4251c6dcb32351219bb553a58838d2
+Create an event when a marked file or directory itself is deleted.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.TP
+.BR FAN_FS_ERROR " (since Linux 5.16)"
+.\" commit 9709bd548f11a092d124698118013f66e1740f9b
+Create an event when a filesystem error
+leading to inconsistent filesystem metadata is detected.
+An additional information record of type
+.B FAN_EVENT_INFO_TYPE_ERROR
+is returned for each event in the read buffer.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.IP
+Events of such type are dependent on support
+from the underlying filesystem.
+At the time of writing,
+only the
+.B ext4
+filesystem reports
+.B FAN_FS_ERROR
+events.
+.IP
+See
+.BR fanotify (7)
+for additional details.
+.TP
+.BR FAN_MOVED_FROM " (since Linux 5.1)"
+.\" commit 235328d1fa4251c6dcb32351219bb553a58838d2
+Create an event when a file or directory has been moved from a marked
+parent directory.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.TP
+.BR FAN_MOVED_TO " (since Linux 5.1)"
+.\" commit 235328d1fa4251c6dcb32351219bb553a58838d2
+Create an event when a file or directory has been moved to a marked parent
+directory.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.TP
+.BR FAN_RENAME " (since Linux 5.17)"
+.\" commit 8cc3b1ccd930fe6971e1527f0c4f1bdc8cb56026
+This event contains the same information provided by events
+.B FAN_MOVED_FROM
+and
+.BR FAN_MOVED_TO ,
+however is represented by a single event with up to two information records.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+If the filesystem object to be marked is not a directory, the error
+.B ENOTDIR
+shall be raised.
+.TP
+.BR FAN_MOVE_SELF " (since Linux 5.1)"
+.\" commit 235328d1fa4251c6dcb32351219bb553a58838d2
+Create an event when a marked file or directory itself has been moved.
+An fanotify group that identifies filesystem objects by file handles
+is required.
+.TP
+.B FAN_OPEN_PERM
+Create an event when a permission to open a file or directory is requested.
+An fanotify file descriptor created with
+.B FAN_CLASS_PRE_CONTENT
+or
+.B FAN_CLASS_CONTENT
+is required.
+.TP
+.BR FAN_OPEN_EXEC_PERM " (since Linux 5.0)"
+.\" commit 66917a3130f218dcef9eeab4fd11a71cd00cd7c9
+Create an event when a permission to open a file for execution is
+requested.
+An fanotify file descriptor created with
+.B FAN_CLASS_PRE_CONTENT
+or
+.B FAN_CLASS_CONTENT
+is required.
+See NOTES for additional details.
+.TP
+.B FAN_ACCESS_PERM
+Create an event when a permission to read a file or directory is requested.
+An fanotify file descriptor created with
+.B FAN_CLASS_PRE_CONTENT
+or
+.B FAN_CLASS_CONTENT
+is required.
+.TP
+.B FAN_ONDIR
+Create events for directories\[em]for example, when
+.BR opendir (3),
+.BR readdir (3)
+(but see BUGS), and
+.BR closedir (3)
+are called.
+Without this flag, events are created only for files.
+In the context of directory entry events, such as
+.BR FAN_CREATE ,
+.BR FAN_DELETE ,
+.BR FAN_MOVED_FROM ,
+and
+.BR FAN_MOVED_TO ,
+specifying the flag
+.B FAN_ONDIR
+is required in order to create events when subdirectory entries are
+modified (i.e.,
+.BR mkdir (2)/
+.BR rmdir (2)).
+.TP
+.B FAN_EVENT_ON_CHILD
+Events for the immediate children of marked directories shall be created.
+The flag has no effect when marking mounts and filesystems.
+Note that events are not generated for children of the subdirectories
+of marked directories.
+More specifically, the directory entry modification events
+.BR FAN_CREATE ,
+.BR FAN_DELETE ,
+.BR FAN_MOVED_FROM ,
+and
+.B FAN_MOVED_TO
+are not generated for any entry modifications performed inside subdirectories
+of marked directories.
+Note that the events
+.B FAN_DELETE_SELF
+and
+.B FAN_MOVE_SELF
+are not generated for children of marked directories.
+To monitor complete directory trees it is necessary to mark the relevant
+mount or filesystem.
+.P
+The following composed values are defined:
+.TP
+.B FAN_CLOSE
+A file is closed
+.RB ( FAN_CLOSE_WRITE | FAN_CLOSE_NOWRITE ).
+.TP
+.B FAN_MOVE
+A file or directory has been moved
+.RB ( FAN_MOVED_FROM | FAN_MOVED_TO ).
+.P
+The filesystem object to be marked is determined by the file descriptor
+.I dirfd
+and the pathname specified in
+.IR pathname :
+.IP \[bu] 3
+If
+.I pathname
+is NULL,
+.I dirfd
+defines the filesystem object to be marked.
+.IP \[bu]
+If
+.I pathname
+is NULL, and
+.I dirfd
+takes the special value
+.BR AT_FDCWD ,
+the current working directory is to be marked.
+.IP \[bu]
+If
+.I pathname
+is absolute, it defines the filesystem object to be marked, and
+.I dirfd
+is ignored.
+.IP \[bu]
+If
+.I pathname
+is relative, and
+.I dirfd
+does not have the value
+.BR AT_FDCWD ,
+then the filesystem object to be marked is determined by interpreting
+.I pathname
+relative the directory referred to by
+.IR dirfd .
+.IP \[bu]
+If
+.I pathname
+is relative, and
+.I dirfd
+has the value
+.BR AT_FDCWD ,
+then the filesystem object to be marked is determined by interpreting
+.I pathname
+relative to the current working directory.
+(See
+.BR openat (2)
+for an explanation of why the
+.I dirfd
+argument is useful.)
+.SH RETURN VALUE
+On success,
+.BR fanotify_mark ()
+returns 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+An invalid file descriptor was passed in
+.IR fanotify_fd .
+.TP
+.B EBADF
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EEXIST
+The filesystem object indicated by
+.I dirfd
+and
+.I pathname
+has a mark that was updated without the
+.B FAN_MARK_EVICTABLE
+flag,
+and the user attempted to update the mark with
+.B FAN_MARK_EVICTABLE
+flag.
+.TP
+.B EEXIST
+The filesystem object indicated by
+.I dirfd
+and
+.I pathname
+has a mark that was updated with the
+.B FAN_MARK_IGNORE
+flag,
+and the user attempted to update the mark with
+.B FAN_MARK_IGNORED_MASK
+flag.
+.TP
+.B EEXIST
+The filesystem object indicated by
+.I dirfd
+and
+.I pathname
+has a mark that was updated with the
+.B FAN_MARK_IGNORE
+and
+.B FAN_MARK_IGNORED_SURV_MODIFY
+flags,
+and the user attempted to update the mark only with
+.B FAN_MARK_IGNORE
+flag.
+.TP
+.B EINVAL
+An invalid value was passed in
+.I flags
+or
+.IR mask ,
+or
+.I fanotify_fd
+was not an fanotify file descriptor.
+.TP
+.B EINVAL
+The fanotify file descriptor was opened with
+.B FAN_CLASS_NOTIF
+or the fanotify group identifies filesystem objects by file handles
+and mask contains a flag for permission events
+.RB ( FAN_OPEN_PERM
+or
+.BR FAN_ACCESS_PERM ).
+.TP
+.B EINVAL
+The group was initialized without
+.B FAN_REPORT_FID
+but one or more event types specified in the
+.I mask
+require it.
+.TP
+.B EINVAL
+.I flags
+contains
+.BR FAN_MARK_IGNORE ,
+and either
+.B FAN_MARK_MOUNT
+or
+.BR FAN_MARK_FILESYSTEM ,
+but does not contain
+.BR FAN_MARK_IGNORED_SURV_MODIFY .
+.TP
+.B EISDIR
+.I flags
+contains
+.BR FAN_MARK_IGNORE ,
+but does not contain
+.BR FAN_MARK_IGNORED_SURV_MODIFY ,
+and
+.I dirfd
+and
+.I pathname
+specify a directory.
+.TP
+.B ENODEV
+The filesystem object indicated by
+.I dirfd
+and
+.I pathname
+is not associated with a filesystem that supports
+.I fsid
+(e.g.,
+.BR fuse (4)).
+.BR tmpfs (5)
+did not support
+.I fsid
+prior to Linux 5.13.
+.\" commit 59cda49ecf6c9a32fae4942420701b6e087204f6
+This error can be returned only with an fanotify group that identifies
+filesystem objects by file handles.
+.TP
+.B ENOENT
+The filesystem object indicated by
+.I dirfd
+and
+.I pathname
+does not exist.
+This error also occurs when trying to remove a mark from an object
+which is not marked.
+.TP
+.B ENOMEM
+The necessary memory could not be allocated.
+.TP
+.B ENOSPC
+The number of marks for this user exceeds the limit and the
+.B FAN_UNLIMITED_MARKS
+flag was not specified when the fanotify file descriptor was created with
+.BR fanotify_init (2).
+See
+.BR fanotify (7)
+for details about this limit.
+.TP
+.B ENOSYS
+This kernel does not implement
+.BR fanotify_mark ().
+The fanotify API is available only if the kernel was configured with
+.BR CONFIG_FANOTIFY .
+.TP
+.B ENOTDIR
+.I flags
+contains
+.BR FAN_MARK_ONLYDIR ,
+and
+.I dirfd
+and
+.I pathname
+do not specify a directory.
+.TP
+.B ENOTDIR
+.I mask
+contains
+.BR FAN_RENAME ,
+and
+.I dirfd
+and
+.I pathname
+do not specify a directory.
+.TP
+.B ENOTDIR
+.I flags
+contains
+.BR FAN_MARK_IGNORE ,
+or the fanotify group was initialized with flag
+.BR FAN_REPORT_TARGET_FID ,
+and
+.I mask
+contains directory entry modification events
+(e.g.,
+.BR FAN_CREATE ,
+.BR FAN_DELETE ),
+or directory event flags
+(e.g.,
+.BR FAN_ONDIR ,
+.BR FAN_EVENT_ON_CHILD ),
+and
+.I dirfd
+and
+.I pathname
+do not specify a directory.
+.TP
+.B EOPNOTSUPP
+The object indicated by
+.I pathname
+is associated with a filesystem
+that does not support the encoding of file handles.
+This error can be returned only with an fanotify group that identifies
+filesystem objects by file handles.
+Calling
+.BR name_to_handle_at (2)
+with the flag
+.BR AT_HANDLE_FID " (since Linux 6.5)"
+.\" commit 96b2b072ee62be8ae68c8ecf14854c4d0505a8f8
+can be used as a test
+to check if a filesystem supports reporting events with file handles.
+.TP
+.B EPERM
+The operation is not permitted because the caller lacks a required capability.
+.TP
+.B EXDEV
+The filesystem object indicated by
+.I pathname
+resides within a filesystem subvolume (e.g.,
+.BR btrfs (5))
+which uses a different
+.I fsid
+than its root superblock.
+This error can be returned only with an fanotify group that identifies
+filesystem objects by file handles.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.37.
+.\" was introduced in Linux 2.6.36 and enabled in Linux 2.6.37.
+.SH NOTES
+.SS FAN_OPEN_EXEC and FAN_OPEN_EXEC_PERM
+When using either
+.B FAN_OPEN_EXEC
+or
+.B FAN_OPEN_EXEC_PERM
+within the
+.IR mask ,
+events of these types will be returned only when the direct execution of a
+program occurs.
+More specifically, this means that events of these types will be generated
+for files that are opened using
+.BR execve (2),
+.BR execveat (2),
+or
+.BR uselib (2).
+Events of these types will not be raised in the situation where an
+interpreter is passed (or reads) a file for interpretation.
+.P
+Additionally, if a mark has also been placed on the Linux dynamic
+linker, a user should also expect to receive an event for it when
+an ELF object has been successfully opened using
+.BR execve (2)
+or
+.BR execveat (2).
+.P
+For example, if the following ELF binary were to be invoked and a
+.B FAN_OPEN_EXEC
+mark has been placed on /:
+.P
+.in +4n
+.EX
+$ /bin/echo foo
+.EE
+.in
+.P
+The listening application in this case would receive
+.B FAN_OPEN_EXEC
+events for both the ELF binary and interpreter, respectively:
+.P
+.in +4n
+.EX
+/bin/echo
+/lib64/ld\-linux\-x86\-64.so.2
+.EE
+.in
+.SH BUGS
+The following bugs were present in before Linux 3.16:
+.IP \[bu] 3
+.\" Fixed by commit 0a8dd2db579f7a0ac7033d6b857c3d5dbaa77563
+If
+.I flags
+contains
+.BR FAN_MARK_FLUSH ,
+.IR dirfd ,
+and
+.I pathname
+must specify a valid filesystem object, even though this object is not used.
+.IP \[bu]
+.\" Fixed by commit d4c7cf6cffb1bc711a833b5e304ba5bcfe76398b
+.BR readdir (2)
+does not generate a
+.B FAN_ACCESS
+event.
+.IP \[bu]
+.\" Fixed by commit cc299a98eb13a9853675a9cbb90b30b4011e1406
+If
+.BR fanotify_mark ()
+is called with
+.BR FAN_MARK_FLUSH ,
+.I flags
+is not checked for invalid values.
+.SH SEE ALSO
+.BR fanotify_init (2),
+.BR fanotify (7)
diff --git a/man/man2/fattach.2 b/man/man2/fattach.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/fattach.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/fchdir.2 b/man/man2/fchdir.2
new file mode 100644
index 000000000..60b9685da
--- /dev/null
+++ b/man/man2/fchdir.2
@@ -0,0 +1 @@
+.so man2/chdir.2
diff --git a/man/man2/fchmod.2 b/man/man2/fchmod.2
new file mode 100644
index 000000000..92647d2e3
--- /dev/null
+++ b/man/man2/fchmod.2
@@ -0,0 +1 @@
+.so man2/chmod.2
diff --git a/man/man2/fchmodat.2 b/man/man2/fchmodat.2
new file mode 100644
index 000000000..92647d2e3
--- /dev/null
+++ b/man/man2/fchmodat.2
@@ -0,0 +1 @@
+.so man2/chmod.2
diff --git a/man/man2/fchown.2 b/man/man2/fchown.2
new file mode 100644
index 000000000..f0a5635ae
--- /dev/null
+++ b/man/man2/fchown.2
@@ -0,0 +1 @@
+.so man2/chown.2
diff --git a/man/man2/fchown32.2 b/man/man2/fchown32.2
new file mode 100644
index 000000000..b8b9452b6
--- /dev/null
+++ b/man/man2/fchown32.2
@@ -0,0 +1 @@
+.so man2/fchown.2
diff --git a/man/man2/fchownat.2 b/man/man2/fchownat.2
new file mode 100644
index 000000000..f0a5635ae
--- /dev/null
+++ b/man/man2/fchownat.2
@@ -0,0 +1 @@
+.so man2/chown.2
diff --git a/man/man2/fcntl.2 b/man/man2/fcntl.2
new file mode 100644
index 000000000..1f9b2d430
--- /dev/null
+++ b/man/man2/fcntl.2
@@ -0,0 +1,2113 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\" and Copyright (C) 1993 Michael Haardt, Ian Jackson;
+.\" and Copyright (C) 1998 Jamie Lokier;
+.\" and Copyright (C) 2002-2010, 2014 Michael Kerrisk;
+.\" and Copyright (C) 2014 Jeff Layton
+.\" and Copyright (C) 2014 David Herrmann
+.\" and Copyright (C) 2017 Jens Axboe
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-09-26 by Andries Brouwer <aeb@cwi.nl>
+.\" and again on 960413 and 980804 and 981223.
+.\" Modified 1998-12-11 by Jamie Lokier <jamie@imbolc.ucc.ie>
+.\" Applied correction by Christian Ehrhardt - aeb, 990712
+.\" Modified 2002-04-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added note on F_SETFL and O_DIRECT
+.\"	Complete rewrite + expansion of material on file locking
+.\"	Incorporated description of F_NOTIFY, drawing on
+.\"		Stephen Rothwell's notes in Documentation/dnotify.txt.
+.\"	Added description of F_SETLEASE and F_GETLEASE
+.\" Corrected and polished, aeb, 020527.
+.\" Modified 2004-03-03 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Modified description of file leases: fixed some errors of detail
+.\"     Replaced the term "lease contestant" by "lease breaker"
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" Modified 2004-12-08, added O_NOATIME after note from Martin Pool
+.\" 2004-12-10, mtk, noted F_GETOWN bug after suggestion from aeb.
+.\" 2005-04-08 Jamie Lokier <jamie@shareable.org>, mtk
+.\"	Described behavior of F_SETOWN/F_SETSIG in
+.\"	multithreaded processes, and generally cleaned
+.\"	up the discussion of F_SETOWN.
+.\" 2005-05-20, Johannes Nicolai <johannes.nicolai@hpi.uni-potsdam.de>,
+.\"	mtk: Noted F_SETOWN bug for socket file descriptor in Linux 2.4
+.\"	and earlier.  Added text on permissions required to send signal.
+.\" 2009-09-30, Michael Kerrisk
+.\"     Note obsolete F_SETOWN behavior with threads.
+.\"     Document F_SETOWN_EX and F_GETOWN_EX
+.\" 2010-06-17, Michael Kerrisk
+.\"	Document F_SETPIPE_SZ and F_GETPIPE_SZ.
+.\" 2014-07-08, David Herrmann <dh.herrmann@gmail.com>
+.\"     Document F_ADD_SEALS and F_GET_SEALS
+.\" 2017-06-26, Jens Axboe <axboe@kernel.dk>
+.\"     Document F_{GET,SET}_RW_HINT and F_{GET,SET}_FILE_RW_HINT
+.\"
+.TH fcntl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fcntl \- manipulate file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <fcntl.h>
+.P
+.BI "int fcntl(int " fd ", int " op ", ... /* " arg " */ );"
+.fi
+.SH DESCRIPTION
+.BR fcntl ()
+performs one of the operations described below on the open file descriptor
+.IR fd .
+The operation is determined by
+.IR op .
+.P
+.BR fcntl ()
+can take an optional third argument.
+Whether or not this argument is required is determined by
+.IR op .
+The required argument type is indicated in parentheses after each
+.I op
+name (in most cases, the required type is
+.IR int ,
+and we identify the argument using the name
+.IR arg ),
+or
+.I void
+is specified if the argument is not required.
+.P
+Certain of the operations below are supported only since a particular
+Linux kernel version.
+The preferred method of checking whether the host kernel supports
+a particular operation is to invoke
+.BR fcntl ()
+with the desired
+.I op
+value and then test whether the call failed with
+.BR EINVAL ,
+indicating that the kernel does not recognize this value.
+.SS Duplicating a file descriptor
+.TP
+.BR F_DUPFD " (\fIint\fP)"
+Duplicate the file descriptor
+.I fd
+using the lowest-numbered available file descriptor greater than or equal to
+.IR arg .
+This is different from
+.BR dup2 (2),
+which uses exactly the file descriptor specified.
+.IP
+On success, the new file descriptor is returned.
+.IP
+See
+.BR dup (2)
+for further details.
+.TP
+.BR F_DUPFD_CLOEXEC " (\fIint\fP; since Linux 2.6.24)"
+As for
+.BR F_DUPFD ,
+but additionally set the
+close-on-exec flag for the duplicate file descriptor.
+Specifying this flag permits a program to avoid an additional
+.BR fcntl ()
+.B F_SETFD
+operation to set the
+.B FD_CLOEXEC
+flag.
+For an explanation of why this flag is useful,
+see the description of
+.B O_CLOEXEC
+in
+.BR open (2).
+.SS File descriptor flags
+The following operations manipulate the flags associated with
+a file descriptor.
+Currently, only one such flag is defined:
+.BR FD_CLOEXEC ,
+the close-on-exec flag.
+If the
+.B FD_CLOEXEC
+bit is set,
+the file descriptor will automatically be closed during a successful
+.BR execve (2).
+(If the
+.BR execve (2)
+fails, the file descriptor is left open.)
+If the
+.B FD_CLOEXEC
+bit is not set, the file descriptor will remain open across an
+.BR execve (2).
+.TP
+.BR F_GETFD " (\fIvoid\fP)"
+Return (as the function result) the file descriptor flags;
+.I arg
+is ignored.
+.TP
+.BR F_SETFD " (\fIint\fP)"
+Set the file descriptor flags to the value specified by
+.IR arg .
+.P
+In multithreaded programs, using
+.BR fcntl ()
+.B F_SETFD
+to set the close-on-exec flag at the same time as another thread performs a
+.BR fork (2)
+plus
+.BR execve (2)
+is vulnerable to a race condition that may unintentionally leak
+the file descriptor to the program executed in the child process.
+See the discussion of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for details and a remedy to the problem.
+.SS File status flags
+Each open file description has certain associated status flags,
+initialized by
+.BR open (2)
+.\" or
+.\" .BR creat (2),
+and possibly modified by
+.BR fcntl ().
+Duplicated file descriptors
+(made with
+.BR dup (2),
+.BR fcntl (F_DUPFD),
+.BR fork (2),
+etc.) refer to the same open file description, and thus
+share the same file status flags.
+.P
+The file status flags and their semantics are described in
+.BR open (2).
+.TP
+.BR F_GETFL " (\fIvoid\fP)"
+Return (as the function result)
+the file access mode and the file status flags;
+.I arg
+is ignored.
+.TP
+.BR F_SETFL " (\fIint\fP)"
+Set the file status flags to the value specified by
+.IR arg .
+File access mode
+.RB ( O_RDONLY ", " O_WRONLY ", " O_RDWR )
+and file creation flags
+(i.e.,
+.BR O_CREAT ", " O_EXCL ", " O_NOCTTY ", " O_TRUNC )
+in
+.I arg
+are ignored.
+On Linux, this operation can change only the
+.BR O_APPEND ,
+.BR O_ASYNC ,
+.BR O_DIRECT ,
+.BR O_NOATIME ,
+and
+.B O_NONBLOCK
+flags.
+It is not possible to change the
+.B O_DSYNC
+and
+.B O_SYNC
+flags; see BUGS, below.
+.SS Advisory record locking
+Linux implements traditional ("process-associated") UNIX record locks,
+as standardized by POSIX.
+For a Linux-specific alternative with better semantics,
+see the discussion of open file description locks below.
+.P
+.BR F_SETLK ,
+.BR F_SETLKW ,
+and
+.B F_GETLK
+are used to acquire, release, and test for the existence of record
+locks (also known as byte-range, file-segment, or file-region locks).
+The third argument,
+.IR lock ,
+is a pointer to a structure that has at least the following fields
+(in unspecified order).
+.P
+.in +4n
+.EX
+struct flock {
+    ...
+    short l_type;    /* Type of lock: F_RDLCK,
+                        F_WRLCK, F_UNLCK */
+    short l_whence;  /* How to interpret l_start:
+                        SEEK_SET, SEEK_CUR, SEEK_END */
+    off_t l_start;   /* Starting offset for lock */
+    off_t l_len;     /* Number of bytes to lock */
+    pid_t l_pid;     /* PID of process blocking our lock
+                        (set by F_GETLK and F_OFD_GETLK) */
+    ...
+};
+.EE
+.in
+.P
+The
+.IR l_whence ", " l_start ", and " l_len
+fields of this structure specify the range of bytes we wish to lock.
+Bytes past the end of the file may be locked,
+but not bytes before the start of the file.
+.P
+.I l_start
+is the starting offset for the lock, and is interpreted
+relative to either:
+the start of the file (if
+.I l_whence
+is
+.BR SEEK_SET );
+the current file offset (if
+.I l_whence
+is
+.BR SEEK_CUR );
+or the end of the file (if
+.I l_whence
+is
+.BR SEEK_END ).
+In the final two cases,
+.I l_start
+can be a negative number provided the
+offset does not lie before the start of the file.
+.P
+.I l_len
+specifies the number of bytes to be locked.
+If
+.I l_len
+is positive, then the range to be locked covers bytes
+.I l_start
+up to and including
+.IR l_start + l_len \-1.
+Specifying 0 for
+.I l_len
+has the special meaning: lock all bytes starting at the
+location specified by
+.IR l_whence " and " l_start
+through to the end of file, no matter how large the file grows.
+.P
+POSIX.1-2001 allows (but does not require)
+an implementation to support a negative
+.I l_len
+value; if
+.I l_len
+is negative, the interval described by
+.I lock
+covers bytes
+.IR l_start + l_len
+up to and including
+.IR l_start \-1.
+This is supported since Linux 2.4.21 and Linux 2.5.49.
+.P
+The
+.I l_type
+field can be used to place a read
+.RB ( F_RDLCK )
+or a write
+.RB ( F_WRLCK )
+lock on a file.
+Any number of processes may hold a read lock (shared lock)
+on a file region, but only one process may hold a write lock
+(exclusive lock).
+An exclusive lock excludes all other locks,
+both shared and exclusive.
+A single process can hold only one type of lock on a file region;
+if a new lock is applied to an already-locked region,
+then the existing lock is converted to the new lock type.
+(Such conversions may involve splitting, shrinking, or coalescing with
+an existing lock if the byte range specified by the new lock does not
+precisely coincide with the range of the existing lock.)
+.TP
+.BR F_SETLK " (\fIstruct flock *\fP)"
+Acquire a lock (when
+.I l_type
+is
+.B F_RDLCK
+or
+.BR F_WRLCK )
+or release a lock (when
+.I l_type
+is
+.BR F_UNLCK )
+on the bytes specified by the
+.IR l_whence ", " l_start ", and " l_len
+fields of
+.IR lock .
+If a conflicting lock is held by another process,
+this call returns \-1 and sets
+.I errno
+to
+.B EACCES
+or
+.BR EAGAIN .
+(The error returned in this case differs across implementations,
+so POSIX requires a portable application to check for both errors.)
+.TP
+.BR F_SETLKW " (\fIstruct flock *\fP)"
+As for
+.BR F_SETLK ,
+but if a conflicting lock is held on the file, then wait for that
+lock to be released.
+If a signal is caught while waiting, then the call is interrupted
+and (after the signal handler has returned)
+returns immediately (with return value \-1 and
+.I errno
+set to
+.BR EINTR ;
+see
+.BR signal (7)).
+.TP
+.BR F_GETLK " (\fIstruct flock *\fP)"
+On input to this call,
+.I lock
+describes a lock we would like to place on the file.
+If the lock could be placed,
+.BR fcntl ()
+does not actually place it, but returns
+.B F_UNLCK
+in the
+.I l_type
+field of
+.I lock
+and leaves the other fields of the structure unchanged.
+.IP
+If one or more incompatible locks would prevent
+this lock being placed, then
+.BR fcntl ()
+returns details about one of those locks in the
+.IR l_type ", " l_whence ", " l_start ", and " l_len
+fields of
+.IR lock .
+If the conflicting lock is a traditional (process-associated) record lock,
+then the
+.I l_pid
+field is set to the PID of the process holding that lock.
+If the conflicting lock is an open file description lock, then
+.I l_pid
+is set to \-1.
+Note that the returned information
+may already be out of date by the time the caller inspects it.
+.P
+In order to place a read lock,
+.I fd
+must be open for reading.
+In order to place a write lock,
+.I fd
+must be open for writing.
+To place both types of lock, open a file read-write.
+.P
+When placing locks with
+.BR F_SETLKW ,
+the kernel detects
+.IR deadlocks ,
+whereby two or more processes have their
+lock requests mutually blocked by locks held by the other processes.
+For example, suppose process A holds a write lock on byte 100 of a file,
+and process B holds a write lock on byte 200.
+If each process then attempts to lock the byte already
+locked by the other process using
+.BR F_SETLKW ,
+then, without deadlock detection,
+both processes would remain blocked indefinitely.
+When the kernel detects such deadlocks,
+it causes one of the blocking lock requests to immediately fail with the error
+.BR EDEADLK ;
+an application that encounters such an error should release
+some of its locks to allow other applications to proceed before
+attempting regain the locks that it requires.
+Circular deadlocks involving more than two processes are also detected.
+Note, however, that there are limitations to the kernel's
+deadlock-detection algorithm; see BUGS.
+.P
+As well as being removed by an explicit
+.BR F_UNLCK ,
+record locks are automatically released when the process terminates.
+.P
+Record locks are not inherited by a child created via
+.BR fork (2),
+but are preserved across an
+.BR execve (2).
+.P
+Because of the buffering performed by the
+.BR stdio (3)
+library, the use of record locking with routines in that package
+should be avoided; use
+.BR read (2)
+and
+.BR write (2)
+instead.
+.P
+The record locks described above are associated with the process
+(unlike the open file description locks described below).
+This has some unfortunate consequences:
+.IP \[bu] 3
+If a process closes
+.I any
+file descriptor referring to a file,
+then all of the process's locks on that file are released,
+regardless of the file descriptor(s) on which the locks were obtained.
+.\" (Additional file descriptors referring to the same file
+.\" may have been obtained by calls to
+.\" .BR open "(2), " dup "(2), " dup2 "(2), or " fcntl ().)
+This is bad: it means that a process can lose its locks on
+a file such as
+.I /etc/passwd
+or
+.I /etc/mtab
+when for some reason a library function decides to open, read,
+and close the same file.
+.IP \[bu]
+The threads in a process share locks.
+In other words,
+a multithreaded program can't use record locking to ensure
+that threads don't simultaneously access the same region of a file.
+.P
+Open file description locks solve both of these problems.
+.SS Open file description locks (non-POSIX)
+Open file description locks are advisory byte-range locks whose operation is
+in most respects identical to the traditional record locks described above.
+This lock type is Linux-specific,
+and available since Linux 3.15.
+(There is a proposal with the Austin Group
+.\" FIXME . Review progress into POSIX
+.\" http://austingroupbugs.net/view.php?id=768
+to include this lock type in the next revision of POSIX.1.)
+For an explanation of open file descriptions, see
+.BR open (2).
+.P
+The principal difference between the two lock types
+is that whereas traditional record locks
+are associated with a process,
+open file description locks are associated with the
+open file description on which they are acquired,
+much like locks acquired with
+.BR flock (2).
+Consequently (and unlike traditional advisory record locks),
+open file description locks are inherited across
+.BR fork (2)
+(and
+.BR clone (2)
+with
+.BR CLONE_FILES ),
+and are only automatically released on the last close
+of the open file description,
+instead of being released on any close of the file.
+.P
+Conflicting lock combinations
+(i.e., a read lock and a write lock or two write locks)
+where one lock is an open file description lock and the other
+is a traditional record lock conflict
+even when they are acquired by the same process on the same file descriptor.
+.P
+Open file description locks placed via the same open file description
+(i.e., via the same file descriptor,
+or via a duplicate of the file descriptor created by
+.BR fork (2),
+.BR dup (2),
+.BR fcntl ()
+.BR F_DUPFD ,
+and so on) are always compatible:
+if a new lock is placed on an already locked region,
+then the existing lock is converted to the new lock type.
+(Such conversions may result in splitting, shrinking, or coalescing with
+an existing lock as discussed above.)
+.P
+On the other hand, open file description locks may conflict with
+each other when they are acquired via different open file descriptions.
+Thus, the threads in a multithreaded program can use
+open file description locks to synchronize access to a file region
+by having each thread perform its own
+.BR open (2)
+on the file and applying locks via the resulting file descriptor.
+.P
+As with traditional advisory locks, the third argument to
+.BR fcntl (),
+.IR lock ,
+is a pointer to an
+.I flock
+structure.
+By contrast with traditional record locks, the
+.I l_pid
+field of that structure must be set to zero
+when using the operations described below.
+.P
+The operations for working with open file description locks are analogous
+to those used with traditional locks:
+.TP
+.BR F_OFD_SETLK " (\fIstruct flock *\fP)"
+Acquire an open file description lock (when
+.I l_type
+is
+.B F_RDLCK
+or
+.BR F_WRLCK )
+or release an open file description lock (when
+.I l_type
+is
+.BR F_UNLCK )
+on the bytes specified by the
+.IR l_whence ", " l_start ", and " l_len
+fields of
+.IR lock .
+If a conflicting lock is held by another process,
+this call returns \-1 and sets
+.I errno
+to
+.BR EAGAIN .
+.TP
+.BR F_OFD_SETLKW " (\fIstruct flock *\fP)"
+As for
+.BR F_OFD_SETLK ,
+but if a conflicting lock is held on the file, then wait for that lock to be
+released.
+If a signal is caught while waiting, then the call is interrupted
+and (after the signal handler has returned) returns immediately
+(with return value \-1 and
+.I errno
+set to
+.BR EINTR ;
+see
+.BR signal (7)).
+.TP
+.BR F_OFD_GETLK " (\fIstruct flock *\fP)"
+On input to this call,
+.I lock
+describes an open file description lock we would like to place on the file.
+If the lock could be placed,
+.BR fcntl ()
+does not actually place it, but returns
+.B F_UNLCK
+in the
+.I l_type
+field of
+.I lock
+and leaves the other fields of the structure unchanged.
+If one or more incompatible locks would prevent this lock being placed,
+then details about one of these locks are returned via
+.IR lock ,
+as described above for
+.BR F_GETLK .
+.P
+In the current implementation,
+.\" commit 57b65325fe34ec4c917bc4e555144b4a94d9e1f7
+no deadlock detection is performed for open file description locks.
+(This contrasts with process-associated record locks,
+for which the kernel does perform deadlock detection.)
+.\"
+.SS Mandatory locking
+.IR Warning :
+the Linux implementation of mandatory locking is unreliable.
+See BUGS below.
+Because of these bugs,
+and the fact that the feature is believed to be little used,
+since Linux 4.5, mandatory locking has been made an optional feature,
+governed by a configuration option
+.RB ( CONFIG_MANDATORY_FILE_LOCKING ).
+This feature is no longer supported at all in Linux 5.15 and above.
+.P
+By default, both traditional (process-associated) and open file description
+record locks are advisory.
+Advisory locks are not enforced and are useful only between
+cooperating processes.
+.P
+Both lock types can also be mandatory.
+Mandatory locks are enforced for all processes.
+If a process tries to perform an incompatible access (e.g.,
+.BR read (2)
+or
+.BR write (2))
+on a file region that has an incompatible mandatory lock,
+then the result depends upon whether the
+.B O_NONBLOCK
+flag is enabled for its open file description.
+If the
+.B O_NONBLOCK
+flag is not enabled, then
+the system call is blocked until the lock is removed
+or converted to a mode that is compatible with the access.
+If the
+.B O_NONBLOCK
+flag is enabled, then the system call fails with the error
+.BR EAGAIN .
+.P
+To make use of mandatory locks, mandatory locking must be enabled
+both on the filesystem that contains the file to be locked,
+and on the file itself.
+Mandatory locking is enabled on a filesystem
+using the "\-o mand" option to
+.BR mount (8),
+or the
+.B MS_MANDLOCK
+flag for
+.BR mount (2).
+Mandatory locking is enabled on a file by disabling
+group execute permission on the file and enabling the set-group-ID
+permission bit (see
+.BR chmod (1)
+and
+.BR chmod (2)).
+.P
+Mandatory locking is not specified by POSIX.
+Some other systems also support mandatory locking,
+although the details of how to enable it vary across systems.
+.\"
+.SS Lost locks
+When an advisory lock is obtained on a networked filesystem such as
+NFS it is possible that the lock might get lost.
+This may happen due to administrative action on the server, or due to a
+network partition (i.e., loss of network connectivity with the server)
+which lasts long enough for the server to assume
+that the client is no longer functioning.
+.P
+When the filesystem determines that a lock has been lost, future
+.BR read (2)
+or
+.BR write (2)
+requests may fail with the error
+.BR EIO .
+This error will persist until the lock is removed or the file
+descriptor is closed.
+Since Linux 3.12,
+.\" commit ef1820f9be27b6ad158f433ab38002ab8131db4d
+this happens at least for NFSv4 (including all minor versions).
+.P
+Some versions of UNIX send a signal
+.RB ( SIGLOST )
+in this circumstance.
+Linux does not define this signal, and does not provide any
+asynchronous notification of lost locks.
+.\"
+.SS Managing signals
+.BR F_GETOWN ,
+.BR F_SETOWN ,
+.BR F_GETOWN_EX ,
+.BR F_SETOWN_EX ,
+.BR F_GETSIG ,
+and
+.B F_SETSIG
+are used to manage I/O availability signals:
+.TP
+.BR F_GETOWN " (\fIvoid\fP)"
+Return (as the function result)
+the process ID or process group ID currently receiving
+.B SIGIO
+and
+.B SIGURG
+signals for events on file descriptor
+.IR fd .
+Process IDs are returned as positive values;
+process group IDs are returned as negative values (but see BUGS below).
+.I arg
+is ignored.
+.TP
+.BR F_SETOWN " (\fIint\fP)"
+Set the process ID or process group ID that will receive
+.B SIGIO
+and
+.B SIGURG
+signals for events on the file descriptor
+.IR fd .
+The target process or process group ID is specified in
+.IR arg .
+A process ID is specified as a positive value;
+a process group ID is specified as a negative value.
+Most commonly, the calling process specifies itself as the owner
+(that is,
+.I arg
+is specified as
+.BR getpid (2)).
+.IP
+As well as setting the file descriptor owner,
+one must also enable generation of signals on the file descriptor.
+This is done by using the
+.BR fcntl ()
+.B F_SETFL
+operation to set the
+.B O_ASYNC
+file status flag on the file descriptor.
+Subsequently, a
+.B SIGIO
+signal is sent whenever input or output becomes possible
+on the file descriptor.
+The
+.BR fcntl ()
+.B F_SETSIG
+operation can be used to obtain delivery of a signal other than
+.BR SIGIO .
+.IP
+Sending a signal to the owner process (group) specified by
+.B F_SETOWN
+is subject to the same permissions checks as are described for
+.BR kill (2),
+where the sending process is the one that employs
+.B F_SETOWN
+(but see BUGS below).
+If this permission check fails, then the signal is
+silently discarded.
+.IR Note :
+The
+.B F_SETOWN
+operation records the caller's credentials at the time of the
+.BR fcntl ()
+call,
+and it is these saved credentials that are used for the permission checks.
+.IP
+If the file descriptor
+.I fd
+refers to a socket,
+.B F_SETOWN
+also selects
+the recipient of
+.B SIGURG
+signals that are delivered when out-of-band
+data arrives on that socket.
+.RB ( SIGURG
+is sent in any situation where
+.BR select (2)
+would report the socket as having an "exceptional condition".)
+.\" The following appears to be rubbish.  It doesn't seem to
+.\" be true according to the kernel source, and I can write
+.\" a program that gets a terminal-generated SIGIO even though
+.\" it is not the foreground process group of the terminal.
+.\" -- MTK, 8 Apr 05
+.\"
+.\" If the file descriptor
+.\" .I fd
+.\" refers to a terminal device, then SIGIO
+.\" signals are sent to the foreground process group of the terminal.
+.IP
+The following was true in Linux 2.6.x up to and including Linux 2.6.11:
+.RS
+.IP
+If a nonzero value is given to
+.B F_SETSIG
+in a multithreaded process running with a threading library
+that supports thread groups (e.g., NPTL),
+then a positive value given to
+.B F_SETOWN
+has a different meaning:
+.\" The relevant place in the (2.6) kernel source is the
+.\" 'switch' in fs/fcntl.c::send_sigio_to_task() -- MTK, Apr 2005
+instead of being a process ID identifying a whole process,
+it is a thread ID identifying a specific thread within a process.
+Consequently, it may be necessary to pass
+.B F_SETOWN
+the result of
+.BR gettid (2)
+instead of
+.BR getpid (2)
+to get sensible results when
+.B F_SETSIG
+is used.
+(In current Linux threading implementations,
+a main thread's thread ID is the same as its process ID.
+This means that a single-threaded program can equally use
+.BR gettid (2)
+or
+.BR getpid (2)
+in this scenario.)
+Note, however, that the statements in this paragraph do not apply
+to the
+.B SIGURG
+signal generated for out-of-band data on a socket:
+this signal is always sent to either a process or a process group,
+depending on the value given to
+.BR F_SETOWN .
+.\" send_sigurg()/send_sigurg_to_task() bypasses
+.\" kill_fasync()/send_sigio()/send_sigio_to_task()
+.\" to directly call send_group_sig_info()
+.\"	-- MTK, Apr 2005 (kernel 2.6.11)
+.RE
+.IP
+The above behavior was accidentally dropped in Linux 2.6.12,
+and won't be restored.
+From Linux 2.6.32 onward, use
+.B F_SETOWN_EX
+to target
+.B SIGIO
+and
+.B SIGURG
+signals at a particular thread.
+.TP
+.BR F_GETOWN_EX " (\fIstruct f_owner_ex *\fP) (since Linux 2.6.32)"
+Return the current file descriptor owner settings
+as defined by a previous
+.B F_SETOWN_EX
+operation.
+The information is returned in the structure pointed to by
+.IR arg ,
+which has the following form:
+.IP
+.in +4n
+.EX
+struct f_owner_ex {
+    int   type;
+    pid_t pid;
+};
+.EE
+.in
+.IP
+The
+.I type
+field will have one of the values
+.BR F_OWNER_TID ,
+.BR F_OWNER_PID ,
+or
+.BR F_OWNER_PGRP .
+The
+.I pid
+field is a positive integer representing a thread ID, process ID,
+or process group ID.
+See
+.B F_SETOWN_EX
+for more details.
+.TP
+.BR F_SETOWN_EX " (\fIstruct f_owner_ex *\fP) (since Linux 2.6.32)"
+This operation performs a similar task to
+.BR F_SETOWN .
+It allows the caller to direct I/O availability signals
+to a specific thread, process, or process group.
+The caller specifies the target of signals via
+.IR arg ,
+which is a pointer to a
+.I f_owner_ex
+structure.
+The
+.I type
+field has one of the following values, which define how
+.I pid
+is interpreted:
+.RS
+.TP
+.B F_OWNER_TID
+Send the signal to the thread whose thread ID
+(the value returned by a call to
+.BR clone (2)
+or
+.BR gettid (2))
+is specified in
+.IR pid .
+.TP
+.B F_OWNER_PID
+Send the signal to the process whose ID
+is specified in
+.IR pid .
+.TP
+.B F_OWNER_PGRP
+Send the signal to the process group whose ID
+is specified in
+.IR pid .
+(Note that, unlike with
+.BR F_SETOWN ,
+a process group ID is specified as a positive value here.)
+.RE
+.TP
+.BR F_GETSIG " (\fIvoid\fP)"
+Return (as the function result)
+the signal sent when input or output becomes possible.
+A value of zero means
+.B SIGIO
+is sent.
+Any other value (including
+.BR SIGIO )
+is the
+signal sent instead, and in this case additional info is available to
+the signal handler if installed with
+.BR SA_SIGINFO .
+.I arg
+is ignored.
+.TP
+.BR F_SETSIG " (\fIint\fP)"
+Set the signal sent when input or output becomes possible
+to the value given in
+.IR arg .
+A value of zero means to send the default
+.B SIGIO
+signal.
+Any other value (including
+.BR SIGIO )
+is the signal to send instead, and in this case additional info
+is available to the signal handler if installed with
+.BR SA_SIGINFO .
+.\"
+.\" The following was true only up until Linux 2.6.11:
+.\"
+.\" Additionally, passing a nonzero value to
+.\" .B F_SETSIG
+.\" changes the signal recipient from a whole process to a specific thread
+.\" within a process.
+.\" See the description of
+.\" .B F_SETOWN
+.\" for more details.
+.IP
+By using
+.B F_SETSIG
+with a nonzero value, and setting
+.B SA_SIGINFO
+for the
+signal handler (see
+.BR sigaction (2)),
+extra information about I/O events is passed to
+the handler in a
+.I siginfo_t
+structure.
+If the
+.I si_code
+field indicates the source is
+.BR SI_SIGIO ,
+the
+.I si_fd
+field gives the file descriptor associated with the event.
+Otherwise,
+there is no indication which file descriptors are pending, and you
+should use the usual mechanisms
+.RB ( select (2),
+.BR poll (2),
+.BR read (2)
+with
+.B O_NONBLOCK
+set etc.) to determine which file descriptors are available for I/O.
+.IP
+Note that the file descriptor provided in
+.I si_fd
+is the one that was specified during the
+.B F_SETSIG
+operation.
+This can lead to an unusual corner case.
+If the file descriptor is duplicated
+.RB ( dup (2)
+or similar), and the original file descriptor is closed,
+then I/O events will continue to be generated, but the
+.I si_fd
+field will contain the number of the now closed file descriptor.
+.IP
+By selecting a real time signal (value >=
+.BR SIGRTMIN ),
+multiple I/O events may be queued using the same signal numbers.
+(Queuing is dependent on available memory.)
+Extra information is available
+if
+.B SA_SIGINFO
+is set for the signal handler, as above.
+.IP
+Note that Linux imposes a limit on the
+number of real-time signals that may be queued to a
+process (see
+.BR getrlimit (2)
+and
+.BR signal (7))
+and if this limit is reached, then the kernel reverts to
+delivering
+.BR SIGIO ,
+and this signal is delivered to the entire
+process rather than to a specific thread.
+.\" See fs/fcntl.c::send_sigio_to_task() (2.4/2.6) sources -- MTK, Apr 05
+.P
+Using these mechanisms, a program can implement fully asynchronous I/O
+without using
+.BR select (2)
+or
+.BR poll (2)
+most of the time.
+.P
+The use of
+.B O_ASYNC
+is specific to BSD and Linux.
+The only use of
+.B F_GETOWN
+and
+.B F_SETOWN
+specified in POSIX.1 is in conjunction with the use of the
+.B SIGURG
+signal on sockets.
+(POSIX does not specify the
+.B SIGIO
+signal.)
+.BR F_GETOWN_EX ,
+.BR F_SETOWN_EX ,
+.BR F_GETSIG ,
+and
+.B F_SETSIG
+are Linux-specific.
+POSIX has asynchronous I/O and the
+.I aio_sigevent
+structure to achieve similar things; these are also available
+in Linux as part of the GNU C Library (glibc).
+.SS Leases
+.B F_SETLEASE
+and
+.B F_GETLEASE
+(Linux 2.4 onward) are used to establish a new lease,
+and retrieve the current lease, on the open file description
+referred to by the file descriptor
+.IR fd .
+A file lease provides a mechanism whereby the process holding
+the lease (the "lease holder") is notified (via delivery of a signal)
+when a process (the "lease breaker") tries to
+.BR open (2)
+or
+.BR truncate (2)
+the file referred to by that file descriptor.
+.TP
+.BR F_SETLEASE " (\fIint\fP)"
+Set or remove a file lease according to which of the following
+values is specified in the integer
+.IR arg :
+.RS
+.TP
+.B F_RDLCK
+Take out a read lease.
+This will cause the calling process to be notified when
+the file is opened for writing or is truncated.
+.\" The following became true in Linux 2.6.10:
+.\" See the man-pages-2.09 Changelog for further info.
+A read lease can be placed only on a file descriptor that
+is opened read-only.
+.TP
+.B F_WRLCK
+Take out a write lease.
+This will cause the caller to be notified when
+the file is opened for reading or writing or is truncated.
+A write lease may be placed on a file only if there are no
+other open file descriptors for the file.
+.TP
+.B F_UNLCK
+Remove our lease from the file.
+.RE
+.P
+Leases are associated with an open file description (see
+.BR open (2)).
+This means that duplicate file descriptors (created by, for example,
+.BR fork (2)
+or
+.BR dup (2))
+refer to the same lease, and this lease may be modified
+or released using any of these descriptors.
+Furthermore, the lease is released by either an explicit
+.B F_UNLCK
+operation on any of these duplicate file descriptors, or when all
+such file descriptors have been closed.
+.P
+Leases may be taken out only on regular files.
+An unprivileged process may take out a lease only on a file whose
+UID (owner) matches the filesystem UID of the process.
+A process with the
+.B CAP_LEASE
+capability may take out leases on arbitrary files.
+.TP
+.BR F_GETLEASE " (\fIvoid\fP)"
+Indicates what type of lease is associated with the file descriptor
+.I fd
+by returning either
+.BR F_RDLCK ", " F_WRLCK ", or " F_UNLCK ,
+indicating, respectively, a read lease , a write lease, or no lease.
+.I arg
+is ignored.
+.P
+When a process (the "lease breaker") performs an
+.BR open (2)
+or
+.BR truncate (2)
+that conflicts with a lease established via
+.BR F_SETLEASE ,
+the system call is blocked by the kernel and
+the kernel notifies the lease holder by sending it a signal
+.RB ( SIGIO
+by default).
+The lease holder should respond to receipt of this signal by doing
+whatever cleanup is required in preparation for the file to be
+accessed by another process (e.g., flushing cached buffers) and
+then either remove or downgrade its lease.
+A lease is removed by performing an
+.B F_SETLEASE
+operation specifying
+.I arg
+as
+.BR F_UNLCK .
+If the lease holder currently holds a write lease on the file,
+and the lease breaker is opening the file for reading,
+then it is sufficient for the lease holder to downgrade
+the lease to a read lease.
+This is done by performing an
+.B F_SETLEASE
+operation specifying
+.I arg
+as
+.BR F_RDLCK .
+.P
+If the lease holder fails to downgrade or remove the lease within
+the number of seconds specified in
+.IR /proc/sys/fs/lease\-break\-time ,
+then the kernel forcibly removes or downgrades the lease holder's lease.
+.P
+Once a lease break has been initiated,
+.B F_GETLEASE
+returns the target lease type (either
+.B F_RDLCK
+or
+.BR F_UNLCK ,
+depending on what would be compatible with the lease breaker)
+until the lease holder voluntarily downgrades or removes the lease or
+the kernel forcibly does so after the lease break timer expires.
+.P
+Once the lease has been voluntarily or forcibly removed or downgraded,
+and assuming the lease breaker has not unblocked its system call,
+the kernel permits the lease breaker's system call to proceed.
+.P
+If the lease breaker's blocked
+.BR open (2)
+or
+.BR truncate (2)
+is interrupted by a signal handler,
+then the system call fails with the error
+.BR EINTR ,
+but the other steps still occur as described above.
+If the lease breaker is killed by a signal while blocked in
+.BR open (2)
+or
+.BR truncate (2),
+then the other steps still occur as described above.
+If the lease breaker specifies the
+.B O_NONBLOCK
+flag when calling
+.BR open (2),
+then the call immediately fails with the error
+.BR EWOULDBLOCK ,
+but the other steps still occur as described above.
+.P
+The default signal used to notify the lease holder is
+.BR SIGIO ,
+but this can be changed using the
+.B F_SETSIG
+operation to
+.BR fcntl ().
+If a
+.B F_SETSIG
+operation is performed (even one specifying
+.BR SIGIO ),
+and the signal
+handler is established using
+.BR SA_SIGINFO ,
+then the handler will receive a
+.I siginfo_t
+structure as its second argument, and the
+.I si_fd
+field of this argument will hold the file descriptor of the leased file
+that has been accessed by another process.
+(This is useful if the caller holds leases against multiple files.)
+.SS File and directory change notification (dnotify)
+.TP
+.BR F_NOTIFY " (\fIint\fP)"
+(Linux 2.4 onward)
+Provide notification when the directory referred to by
+.I fd
+or any of the files that it contains is changed.
+The events to be notified are specified in
+.IR arg ,
+which is a bit mask specified by ORing together zero or more of
+the following bits:
+.P
+.RS
+.PD 0
+.TP
+.B DN_ACCESS
+A file was accessed
+.RB ( read (2),
+.BR pread (2),
+.BR readv (2),
+and similar)
+.TP
+.B DN_MODIFY
+A file was modified
+.RB ( write (2),
+.BR pwrite (2),
+.BR writev (2),
+.BR truncate (2),
+.BR ftruncate (2),
+and similar).
+.TP
+.B DN_CREATE
+A file was created
+.RB ( open (2),
+.BR creat (2),
+.BR mknod (2),
+.BR mkdir (2),
+.BR link (2),
+.BR symlink (2),
+.BR rename (2)
+into this directory).
+.TP
+.B DN_DELETE
+A file was unlinked
+.RB ( unlink (2),
+.BR rename (2)
+to another directory,
+.BR rmdir (2)).
+.TP
+.B DN_RENAME
+A file was renamed within this directory
+.RB ( rename (2)).
+.TP
+.B DN_ATTRIB
+The attributes of a file were changed
+.RB ( chown (2),
+.BR chmod (2),
+.BR utime (2),
+.BR utimensat (2),
+and similar).
+.PD
+.RE
+.IP
+(In order to obtain these definitions, the
+.B _GNU_SOURCE
+feature test macro must be defined before including
+.I any
+header files.)
+.IP
+Directory notifications are normally "one-shot", and the application
+must reregister to receive further notifications.
+Alternatively, if
+.B DN_MULTISHOT
+is included in
+.IR arg ,
+then notification will remain in effect until explicitly removed.
+.IP
+.\" The following does seem a poor API-design choice...
+A series of
+.B F_NOTIFY
+requests is cumulative, with the events in
+.I arg
+being added to the set already monitored.
+To disable notification of all events, make an
+.B F_NOTIFY
+call specifying
+.I arg
+as 0.
+.IP
+Notification occurs via delivery of a signal.
+The default signal is
+.BR SIGIO ,
+but this can be changed using the
+.B F_SETSIG
+operation to
+.BR fcntl ().
+(Note that
+.B SIGIO
+is one of the nonqueuing standard signals;
+switching to the use of a real-time signal means that
+multiple notifications can be queued to the process.)
+In the latter case, the signal handler receives a
+.I siginfo_t
+structure as its second argument (if the handler was
+established using
+.BR SA_SIGINFO )
+and the
+.I si_fd
+field of this structure contains the file descriptor which
+generated the notification (useful when establishing notification
+on multiple directories).
+.IP
+Especially when using
+.BR DN_MULTISHOT ,
+a real time signal should be used for notification,
+so that multiple notifications can be queued.
+.IP
+.B NOTE:
+New applications should use the
+.I inotify
+interface (available since Linux 2.6.13),
+which provides a much superior interface for obtaining notifications of
+filesystem events.
+See
+.BR inotify (7).
+.SS Changing the capacity of a pipe
+.TP
+.BR F_SETPIPE_SZ " (\fIint\fP; since Linux 2.6.35)"
+Change the capacity of the pipe referred to by
+.I fd
+to be at least
+.I arg
+bytes.
+An unprivileged process can adjust the pipe capacity to any value
+between the system page size and the limit defined in
+.I /proc/sys/fs/pipe\-max\-size
+(see
+.BR proc (5)).
+Attempts to set the pipe capacity below the page size are silently
+rounded up to the page size.
+Attempts by an unprivileged process to set the pipe capacity above the limit in
+.I /proc/sys/fs/pipe\-max\-size
+yield the error
+.BR EPERM ;
+a privileged process
+.RB ( CAP_SYS_RESOURCE )
+can override the limit.
+.IP
+When allocating the buffer for the pipe,
+the kernel may use a capacity larger than
+.IR arg ,
+if that is convenient for the implementation.
+(In the current implementation,
+the allocation is the next higher power-of-two page-size multiple
+of the requested size.)
+The actual capacity (in bytes) that is set is returned as the function result.
+.IP
+Attempting to set the pipe capacity smaller than the amount
+of buffer space currently used to store data produces the error
+.BR EBUSY .
+.IP
+Note that because of the way the pages of the pipe buffer
+are employed when data is written to the pipe,
+the number of bytes that can be written may be less than the nominal size,
+depending on the size of the writes.
+.TP
+.BR F_GETPIPE_SZ " (\fIvoid\fP; since Linux 2.6.35)"
+Return (as the function result) the capacity of the pipe referred to by
+.IR fd .
+.\"
+.SS File Sealing
+File seals limit the set of allowed operations on a given file.
+For each seal that is set on a file,
+a specific set of operations will fail with
+.B EPERM
+on this file from now on.
+The file is said to be sealed.
+The default set of seals depends on the type of the underlying
+file and filesystem.
+For an overview of file sealing, a discussion of its purpose,
+and some code examples, see
+.BR memfd_create (2).
+.P
+Currently,
+file seals can be applied only to a file descriptor returned by
+.BR memfd_create (2)
+(if the
+.B MFD_ALLOW_SEALING
+was employed).
+On other filesystems, all
+.BR fcntl ()
+operations that operate on seals will return
+.BR EINVAL .
+.P
+Seals are a property of an inode.
+Thus, all open file descriptors referring to the same inode share
+the same set of seals.
+Furthermore, seals can never be removed, only added.
+.TP
+.BR F_ADD_SEALS " (\fIint\fP; since Linux 3.17)"
+Add the seals given in the bit-mask argument
+.I arg
+to the set of seals of the inode referred to by the file descriptor
+.IR fd .
+Seals cannot be removed again.
+Once this call succeeds, the seals are enforced by the kernel immediately.
+If the current set of seals includes
+.B F_SEAL_SEAL
+(see below), then this call will be rejected with
+.BR EPERM .
+Adding a seal that is already set is a no-op, in case
+.B F_SEAL_SEAL
+is not set already.
+In order to place a seal, the file descriptor
+.I fd
+must be writable.
+.TP
+.BR F_GET_SEALS " (\fIvoid\fP; since Linux 3.17)"
+Return (as the function result) the current set of seals
+of the inode referred to by
+.IR fd .
+If no seals are set, 0 is returned.
+If the file does not support sealing, \-1 is returned and
+.I errno
+is set to
+.BR EINVAL .
+.P
+The following seals are available:
+.TP
+.B F_SEAL_SEAL
+If this seal is set, any further call to
+.BR fcntl ()
+with
+.B F_ADD_SEALS
+fails with the error
+.BR EPERM .
+Therefore, this seal prevents any modifications to the set of seals itself.
+If the initial set of seals of a file includes
+.BR F_SEAL_SEAL ,
+then this effectively causes the set of seals to be constant and locked.
+.TP
+.B F_SEAL_SHRINK
+If this seal is set, the file in question cannot be reduced in size.
+This affects
+.BR open (2)
+with the
+.B O_TRUNC
+flag as well as
+.BR truncate (2)
+and
+.BR ftruncate (2).
+Those calls fail with
+.B EPERM
+if you try to shrink the file in question.
+Increasing the file size is still possible.
+.TP
+.B F_SEAL_GROW
+If this seal is set, the size of the file in question cannot be increased.
+This affects
+.BR write (2)
+beyond the end of the file,
+.BR truncate (2),
+.BR ftruncate (2),
+and
+.BR fallocate (2).
+These calls fail with
+.B EPERM
+if you use them to increase the file size.
+If you keep the size or shrink it, those calls still work as expected.
+.TP
+.B F_SEAL_WRITE
+If this seal is set, you cannot modify the contents of the file.
+Note that shrinking or growing the size of the file is
+still possible and allowed.
+.\" One or more other seals are typically used with F_SEAL_WRITE
+.\" because, given a file with the F_SEAL_WRITE seal set, then,
+.\" while it would no longer be possible to (say) write zeros into
+.\" the last 100 bytes of a file, it would still be possible
+.\" to (say) shrink the file by 100 bytes using ftruncate(), and
+.\" then increase the file size by 100 bytes, which would have
+.\" the effect of replacing the last hundred bytes by zeros.
+.\"
+Thus, this seal is normally used in combination with one of the other seals.
+This seal affects
+.BR write (2)
+and
+.BR fallocate (2)
+(only in combination with the
+.B FALLOC_FL_PUNCH_HOLE
+flag).
+Those calls fail with
+.B EPERM
+if this seal is set.
+Furthermore, trying to create new shared, writable memory-mappings via
+.BR mmap (2)
+will also fail with
+.BR EPERM .
+.IP
+Using the
+.B F_ADD_SEALS
+operation to set the
+.B F_SEAL_WRITE
+seal fails with
+.B EBUSY
+if any writable, shared mapping exists.
+Such mappings must be unmapped before you can add this seal.
+Furthermore, if there are any asynchronous I/O operations
+.RB ( io_submit (2))
+pending on the file,
+all outstanding writes will be discarded.
+.TP
+.BR F_SEAL_FUTURE_WRITE " (since Linux 5.1)"
+The effect of this seal is similar to
+.BR F_SEAL_WRITE ,
+but the contents of the file can still be modified via
+shared writable mappings that were created prior to the seal being set.
+Any attempt to create a new writable mapping on the file via
+.BR mmap (2)
+will fail with
+.BR EPERM .
+Likewise, an attempt to write to the file via
+.BR write (2)
+will fail with
+.BR EPERM .
+.IP
+Using this seal,
+one process can create a memory buffer that it can continue to modify
+while sharing that buffer on a "read-only" basis with other processes.
+.\"
+.SS File read/write hints
+Write lifetime hints can be used to inform the kernel about the relative
+expected lifetime of writes on a given inode or
+via a particular open file description.
+(See
+.BR open (2)
+for an explanation of open file descriptions.)
+In this context, the term "write lifetime" means
+the expected time the data will live on media, before
+being overwritten or erased.
+.P
+An application may use the different hint values specified below to
+separate writes into different write classes,
+so that multiple users or applications running on a single storage back-end
+can aggregate their I/O patterns in a consistent manner.
+However, there are no functional semantics implied by these flags,
+and different I/O classes can use the write lifetime hints
+in arbitrary ways, so long as the hints are used consistently.
+.P
+The following operations can be applied to the file descriptor,
+.IR fd :
+.TP
+.BR F_GET_RW_HINT " (\fIuint64_t *\fP; since Linux 4.13)"
+Returns the value of the read/write hint associated with the underlying inode
+referred to by
+.IR fd .
+.TP
+.BR F_SET_RW_HINT " (\fIuint64_t *\fP; since Linux 4.13)"
+Sets the read/write hint value associated with the
+underlying inode referred to by
+.IR fd .
+This hint persists until either it is explicitly modified or
+the underlying filesystem is unmounted.
+.TP
+.BR F_GET_FILE_RW_HINT " (\fIuint64_t *\fP; since Linux 4.13)"
+Returns the value of the read/write hint associated with
+the open file description referred to by
+.IR fd .
+.TP
+.BR F_SET_FILE_RW_HINT " (\fIuint64_t *\fP; since Linux 4.13)"
+Sets the read/write hint value associated with the open file description
+referred to by
+.IR fd .
+.P
+If an open file description has not been assigned a read/write hint,
+then it shall use the value assigned to the inode, if any.
+.P
+The following read/write
+hints are valid since Linux 4.13:
+.TP
+.B RWH_WRITE_LIFE_NOT_SET
+No specific hint has been set.
+This is the default value.
+.TP
+.B RWH_WRITE_LIFE_NONE
+No specific write lifetime is associated with this file or inode.
+.TP
+.B RWH_WRITE_LIFE_SHORT
+Data written to this inode or via this open file description
+is expected to have a short lifetime.
+.TP
+.B RWH_WRITE_LIFE_MEDIUM
+Data written to this inode or via this open file description
+is expected to have a lifetime longer than
+data written with
+.BR RWH_WRITE_LIFE_SHORT .
+.TP
+.B RWH_WRITE_LIFE_LONG
+Data written to this inode or via this open file description
+is expected to have a lifetime longer than
+data written with
+.BR RWH_WRITE_LIFE_MEDIUM .
+.TP
+.B RWH_WRITE_LIFE_EXTREME
+Data written to this inode or via this open file description
+is expected to have a lifetime longer than
+data written with
+.BR RWH_WRITE_LIFE_LONG .
+.P
+All the write-specific hints are relative to each other,
+and no individual absolute meaning should be attributed to them.
+.SH RETURN VALUE
+For a successful call, the return value depends on the operation:
+.TP
+.B F_DUPFD
+The new file descriptor.
+.TP
+.B F_GETFD
+Value of file descriptor flags.
+.TP
+.B F_GETFL
+Value of file status flags.
+.TP
+.B F_GETLEASE
+Type of lease held on file descriptor.
+.TP
+.B F_GETOWN
+Value of file descriptor owner.
+.TP
+.B F_GETSIG
+Value of signal sent when read or write becomes possible, or zero
+for traditional
+.B SIGIO
+behavior.
+.TP
+.B F_GETPIPE_SZ
+.TQ
+.B F_SETPIPE_SZ
+The pipe capacity.
+.TP
+.B F_GET_SEALS
+A bit mask identifying the seals that have been set
+for the inode referred to by
+.IR fd .
+.TP
+All other operations
+Zero.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.BR EACCES " or " EAGAIN
+Operation is prohibited by locks held by other processes.
+.TP
+.B EAGAIN
+The operation is prohibited because the file has been memory-mapped by
+another process.
+.TP
+.B EBADF
+.I fd
+is not an open file descriptor
+.TP
+.B EBADF
+.I op
+is
+.B F_SETLK
+or
+.B F_SETLKW
+and the file descriptor open mode doesn't match with the
+type of lock requested.
+.TP
+.B EBUSY
+.I op
+is
+.B F_SETPIPE_SZ
+and the new pipe capacity specified in
+.I arg
+is smaller than the amount of buffer space currently
+used to store data in the pipe.
+.TP
+.B EBUSY
+.I op
+is
+.BR F_ADD_SEALS ,
+.I arg
+includes
+.BR F_SEAL_WRITE ,
+and there exists a writable, shared mapping on the file referred to by
+.IR fd .
+.TP
+.B EDEADLK
+It was detected that the specified
+.B F_SETLKW
+operation would cause a deadlock.
+.TP
+.B EFAULT
+.I lock
+is outside your accessible address space.
+.TP
+.B EINTR
+.I op
+is
+.B F_SETLKW
+or
+.B F_OFD_SETLKW
+and the operation was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EINTR
+.I op
+is
+.BR F_GETLK ,
+.BR F_SETLK ,
+.BR F_OFD_GETLK ,
+or
+.BR F_OFD_SETLK ,
+and the operation was interrupted by a signal before the lock was checked or
+acquired.
+Most likely when locking a remote file (e.g., locking over
+NFS), but can sometimes happen locally.
+.TP
+.B EINVAL
+The value specified in
+.I op
+is not recognized by this kernel.
+.TP
+.B EINVAL
+.I op
+is
+.B F_ADD_SEALS
+and
+.I arg
+includes an unrecognized sealing bit.
+.TP
+.B EINVAL
+.I op
+is
+.B F_ADD_SEALS
+or
+.B F_GET_SEALS
+and the filesystem containing the inode referred to by
+.I fd
+does not support sealing.
+.TP
+.B EINVAL
+.I op
+is
+.B F_DUPFD
+and
+.I arg
+is negative or is greater than the maximum allowable value
+(see the discussion of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2)).
+.TP
+.B EINVAL
+.I op
+is
+.B F_SETSIG
+and
+.I arg
+is not an allowable signal number.
+.TP
+.B EINVAL
+.I op
+is
+.BR F_OFD_SETLK ,
+.BR F_OFD_SETLKW ,
+or
+.BR F_OFD_GETLK ,
+and
+.I l_pid
+was not specified as zero.
+.TP
+.B EMFILE
+.I op
+is
+.B F_DUPFD
+and the per-process limit on the number of open file descriptors
+has been reached.
+.TP
+.B ENOLCK
+Too many segment locks open, lock table is full, or a remote locking
+protocol failed (e.g., locking over NFS).
+.TP
+.B ENOTDIR
+.B F_NOTIFY
+was specified in
+.IR op ,
+but
+.I fd
+does not refer to a directory.
+.TP
+.B EPERM
+.I op
+is
+.B F_SETPIPE_SZ
+and the soft or hard user pipe limit has been reached; see
+.BR pipe (7).
+.TP
+.B EPERM
+Attempted to clear the
+.B O_APPEND
+flag on a file that has the append-only attribute set.
+.TP
+.B EPERM
+.I op
+was
+.BR F_ADD_SEALS ,
+but
+.I fd
+was not open for writing
+or the current set of seals on the file already includes
+.BR F_SEAL_SEAL .
+.SH STANDARDS
+POSIX.1-2008.
+.P
+.BR F_GETOWN_EX ,
+.BR F_SETOWN_EX ,
+.BR F_SETPIPE_SZ ,
+.BR F_GETPIPE_SZ ,
+.BR F_GETSIG ,
+.BR F_SETSIG ,
+.BR F_NOTIFY ,
+.BR F_GETLEASE ,
+and
+.B F_SETLEASE
+are Linux-specific.
+(Define the
+.B _GNU_SOURCE
+macro to obtain these definitions.)
+.\" .P
+.\" SVr4 documents additional EIO, ENOLINK and EOVERFLOW error conditions.
+.P
+.BR F_OFD_SETLK ,
+.BR F_OFD_SETLKW ,
+and
+.B F_OFD_GETLK
+are Linux-specific (and one must define
+.B _GNU_SOURCE
+to obtain their definitions),
+but work is being done to have them included in the next version of POSIX.1.
+.P
+.B F_ADD_SEALS
+and
+.B F_GET_SEALS
+are Linux-specific.
+.\" FIXME . Once glibc adds support, add a note about FTM requirements
+.SH HISTORY
+SVr4, 4.3BSD, POSIX.1-2001.
+.P
+Only the operations
+.BR F_DUPFD ,
+.BR F_GETFD ,
+.BR F_SETFD ,
+.BR F_GETFL ,
+.BR F_SETFL ,
+.BR F_GETLK ,
+.BR F_SETLK ,
+and
+.B F_SETLKW
+are specified in POSIX.1-2001.
+.P
+.B F_GETOWN
+and
+.B F_SETOWN
+are specified in POSIX.1-2001.
+(To get their definitions, define either
+.\" .BR _BSD_SOURCE ,
+.\" or
+.B _XOPEN_SOURCE
+with the value 500 or greater, or
+.B _POSIX_C_SOURCE
+with the value 200809L or greater.)
+.P
+.B F_DUPFD_CLOEXEC
+is specified in POSIX.1-2008.
+(To get this definition, define
+.B _POSIX_C_SOURCE
+with the value 200809L or greater, or
+.B _XOPEN_SOURCE
+with the value 700 or greater.)
+.SH NOTES
+The errors returned by
+.BR dup2 (2)
+are different from those returned by
+.BR F_DUPFD .
+.\"
+.SS File locking
+The original Linux
+.BR fcntl ()
+system call was not designed to handle large file offsets
+(in the
+.I flock
+structure).
+Consequently, an
+.BR fcntl64 ()
+system call was added in Linux 2.4.
+The newer system call employs a different structure for file locking,
+.IR flock64 ,
+and corresponding operations,
+.BR F_GETLK64 ,
+.BR F_SETLK64 ,
+and
+.BR F_SETLKW64 .
+However, these details can be ignored by applications using glibc, whose
+.BR fcntl ()
+wrapper function transparently employs the more recent system call
+where it is available.
+.\"
+.SS Record locks
+Since Linux 2.0, there is no interaction between the types of lock
+placed by
+.BR flock (2)
+and
+.BR fcntl ().
+.P
+Several systems have more fields in
+.I "struct flock"
+such as, for example,
+.I l_sysid
+(to identify the machine where the lock is held).
+.\" e.g., Solaris 8 documents this field in fcntl(2), and Irix 6.5
+.\" documents it in fcntl(5).  mtk, May 2007
+.\" Also, FreeBSD documents it (Apr 2014).
+Clearly,
+.I l_pid
+alone is not going to be very useful if the process holding the lock
+may live on a different machine;
+on Linux, while present on some architectures (such as MIPS32),
+this field is not used.
+.P
+The original Linux
+.BR fcntl ()
+system call was not designed to handle large file offsets
+(in the
+.I flock
+structure).
+Consequently, an
+.BR fcntl64 ()
+system call was added in Linux 2.4.
+The newer system call employs a different structure for file locking,
+.IR flock64 ,
+and corresponding operations,
+.BR F_GETLK64 ,
+.BR F_SETLK64 ,
+and
+.BR F_SETLKW64 .
+However, these details can be ignored by applications using glibc, whose
+.BR fcntl ()
+wrapper function transparently employs the more recent system call
+where it is available.
+.SS Record locking and NFS
+Before Linux 3.12, if an NFSv4 client
+loses contact with the server for a period of time
+(defined as more than 90 seconds with no communication),
+.\"
+.\" Neil Brown: With NFSv3 the failure mode is the reverse.  If
+.\"     the server loses contact with a client then any lock stays in place
+.\"     indefinitely ("why can't I read my mail"... I remember it well).
+.\"
+it might lose and regain a lock without ever being aware of the fact.
+(The period of time after which contact is assumed lost is known as
+the NFSv4 leasetime.
+On a Linux NFS server, this can be determined by looking at
+.IR /proc/fs/nfsd/nfsv4leasetime ,
+which expresses the period in seconds.
+The default value for this file is 90.)
+.\"
+.\" Jeff Layton:
+.\"     Note that this is not a firm timeout. The server runs a job
+.\"     periodically to clean out expired stateful objects, and it's likely
+.\"     that there is some time (maybe even up to another whole lease period)
+.\"     between when the timeout expires and the job actually runs. If the
+.\"     client gets a RENEW in there within that window, its lease will be
+.\"     renewed and its state preserved.
+.\"
+This scenario potentially risks data corruption,
+since another process might acquire a lock in the intervening period
+and perform file I/O.
+.P
+Since Linux 3.12,
+.\" commit ef1820f9be27b6ad158f433ab38002ab8131db4d
+if an NFSv4 client loses contact with the server,
+any I/O to the file by a process which "thinks" it holds
+a lock will fail until that process closes and reopens the file.
+A kernel parameter,
+.IR nfs.recover_lost_locks ,
+can be set to 1 to obtain the pre-3.12 behavior,
+whereby the client will attempt to recover lost locks
+when contact is reestablished with the server.
+Because of the attendant risk of data corruption,
+.\" commit f6de7a39c181dfb8a2c534661a53c73afb3081cd
+this parameter defaults to 0 (disabled).
+.SH BUGS
+.SS F_SETFL
+It is not possible to use
+.B F_SETFL
+to change the state of the
+.B O_DSYNC
+and
+.B O_SYNC
+flags.
+.\" FIXME . According to POSIX.1-2001, O_SYNC should also be modifiable
+.\" via fcntl(2), but currently Linux does not permit this
+.\" See http://bugzilla.kernel.org/show_bug.cgi?id=5994
+Attempts to change the state of these flags are silently ignored.
+.SS F_GETOWN
+A limitation of the Linux system call conventions on some
+architectures (notably i386) means that if a (negative)
+process group ID to be returned by
+.B F_GETOWN
+falls in the range \-1 to \-4095, then the return value is wrongly
+interpreted by glibc as an error in the system call;
+.\" glibc source: sysdeps/unix/sysv/linux/i386/sysdep.h
+that is, the return value of
+.BR fcntl ()
+will be \-1, and
+.I errno
+will contain the (positive) process group ID.
+The Linux-specific
+.B F_GETOWN_EX
+operation avoids this problem.
+.\" mtk, Dec 04: some limited testing on alpha and ia64 seems to
+.\" indicate that ANY negative PGID value will cause F_GETOWN
+.\" to misinterpret the return as an error. Some other architectures
+.\" seem to have the same range check as i386.
+Since glibc 2.11, glibc makes the kernel
+.B F_GETOWN
+problem invisible by implementing
+.B F_GETOWN
+using
+.BR F_GETOWN_EX .
+.SS F_SETOWN
+In Linux 2.4 and earlier, there is bug that can occur
+when an unprivileged process uses
+.B F_SETOWN
+to specify the owner
+of a socket file descriptor
+as a process (group) other than the caller.
+In this case,
+.BR fcntl ()
+can return \-1 with
+.I errno
+set to
+.BR EPERM ,
+even when the owner process (group) is one that the caller
+has permission to send signals to.
+Despite this error return, the file descriptor owner is set,
+and signals will be sent to the owner.
+.\"
+.SS Deadlock detection
+The deadlock-detection algorithm employed by the kernel when dealing with
+.B F_SETLKW
+requests can yield both
+false negatives (failures to detect deadlocks,
+leaving a set of deadlocked processes blocked indefinitely)
+and false positives
+.RB ( EDEADLK
+errors when there is no deadlock).
+For example,
+the kernel limits the lock depth of its dependency search to 10 steps,
+meaning that circular deadlock chains that exceed
+that size will not be detected.
+In addition, the kernel may falsely indicate a deadlock
+when two or more processes created using the
+.BR clone (2)
+.B CLONE_FILES
+flag place locks that appear (to the kernel) to conflict.
+.\"
+.SS Mandatory locking
+The Linux implementation of mandatory locking
+is subject to race conditions which render it unreliable:
+.\" http://marc.info/?l=linux-kernel&m=119013491707153&w=2
+.\"
+.\" Reconfirmed by Jeff Layton
+.\"     From: Jeff Layton <jlayton <at> redhat.com>
+.\"     Subject: Re: Status of fcntl() mandatory locking
+.\"     Newsgroups: gmane.linux.file-systems
+.\"     Date: 2014-04-28 10:07:57 GMT
+.\"     http://thread.gmane.org/gmane.linux.file-systems/84481/focus=84518
+a
+.BR write (2)
+call that overlaps with a lock may modify data after the mandatory lock is
+acquired;
+a
+.BR read (2)
+call that overlaps with a lock may detect changes to data that were made
+only after a write lock was acquired.
+Similar races exist between mandatory locks and
+.BR mmap (2).
+It is therefore inadvisable to rely on mandatory locking.
+.SH SEE ALSO
+.BR dup2 (2),
+.BR flock (2),
+.BR open (2),
+.BR socket (2),
+.BR lockf (3),
+.BR capabilities (7),
+.BR feature_test_macros (7),
+.BR lslocks (8)
+.P
+.IR locks.txt ,
+.IR mandatory\-locking.txt ,
+and
+.I dnotify.txt
+in the Linux kernel source directory
+.I Documentation/filesystems/
+(on older kernels, these files are directly under the
+.I Documentation/
+directory, and
+.I mandatory\-locking.txt
+is called
+.IR mandatory.txt )
diff --git a/man/man2/fcntl64.2 b/man/man2/fcntl64.2
new file mode 100644
index 000000000..fc8ddc17d
--- /dev/null
+++ b/man/man2/fcntl64.2
@@ -0,0 +1 @@
+.so man2/fcntl.2
diff --git a/man/man2/fdatasync.2 b/man/man2/fdatasync.2
new file mode 100644
index 000000000..3c7494f37
--- /dev/null
+++ b/man/man2/fdatasync.2
@@ -0,0 +1 @@
+.so man2/fsync.2
diff --git a/man/man2/fdetach.2 b/man/man2/fdetach.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/fdetach.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/fgetxattr.2 b/man/man2/fgetxattr.2
new file mode 100644
index 000000000..d9e5d9037
--- /dev/null
+++ b/man/man2/fgetxattr.2
@@ -0,0 +1 @@
+.so man2/getxattr.2
diff --git a/man/man2/finit_module.2 b/man/man2/finit_module.2
new file mode 100644
index 000000000..20c5c51f8
--- /dev/null
+++ b/man/man2/finit_module.2
@@ -0,0 +1 @@
+.so man2/init_module.2
diff --git a/man/man2/flistxattr.2 b/man/man2/flistxattr.2
new file mode 100644
index 000000000..117bd2b53
--- /dev/null
+++ b/man/man2/flistxattr.2
@@ -0,0 +1 @@
+.so man2/listxattr.2
diff --git a/man/man2/flock.2 b/man/man2/flock.2
new file mode 100644
index 000000000..9c8f5b3b7
--- /dev/null
+++ b/man/man2/flock.2
@@ -0,0 +1,267 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu) and
+.\" and Copyright 2002 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Fri Jan 31 16:26:07 1997 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Fri Dec 11 17:57:27 1998 by Jamie Lokier <jamie@imbolc.ucc.ie>
+.\" Modified 24 Apr 2002 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Substantial rewrites and additions
+.\" 2005-05-10 mtk, noted that lock conversions are not atomic.
+.\"
+.\" FIXME Maybe document LOCK_MAND, LOCK_RW, LOCK_READ, LOCK_WRITE
+.\" which only have effect for SAMBA.
+.\"
+.TH flock 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+flock \- apply or remove an advisory lock on an open file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/file.h>
+.P
+.BI "int flock(int " fd ", int " op );
+.fi
+.SH DESCRIPTION
+Apply or remove an advisory lock on the open file specified by
+.IR fd .
+The argument
+.I op
+is one of the following:
+.RS 4
+.TP 9
+.B LOCK_SH
+Place a shared lock.
+More than one process may hold a shared lock for a given file
+at a given time.
+.TP
+.B LOCK_EX
+Place an exclusive lock.
+Only one process may hold an exclusive lock for a given
+file at a given time.
+.TP
+.B LOCK_UN
+Remove an existing lock held by this process.
+.RE
+.P
+A call to
+.BR flock ()
+may block if an incompatible lock is held by another process.
+To make a nonblocking request, include
+.B LOCK_NB
+(by ORing)
+with any of the above operations.
+.P
+A single file may not simultaneously have both shared and exclusive locks.
+.P
+Locks created by
+.BR flock ()
+are associated with an open file description (see
+.BR open (2)).
+This means that duplicate file descriptors (created by, for example,
+.BR fork (2)
+or
+.BR dup (2))
+refer to the same lock, and this lock may be modified
+or released using any of these file descriptors.
+Furthermore, the lock is released either by an explicit
+.B LOCK_UN
+operation on any of these duplicate file descriptors, or when all
+such file descriptors have been closed.
+.P
+If a process uses
+.BR open (2)
+(or similar) to obtain more than one file descriptor for the same file,
+these file descriptors are treated independently by
+.BR flock ().
+An attempt to lock the file using one of these file descriptors
+may be denied by a lock that the calling process has
+already placed via another file descriptor.
+.P
+A process may hold only one type of lock (shared or exclusive)
+on a file.
+Subsequent
+.BR flock ()
+calls on an already locked file will convert an existing lock to the new
+lock mode.
+.P
+Locks created by
+.BR flock ()
+are preserved across an
+.BR execve (2).
+.P
+A shared or exclusive lock can be placed on a file regardless of the
+mode in which the file was opened.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not an open file descriptor.
+.TP
+.B EINTR
+While waiting to acquire a lock, the call was interrupted by
+delivery of a signal caught by a handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I op
+is invalid.
+.TP
+.B ENOLCK
+The kernel ran out of memory for allocating lock records.
+.TP
+.B EWOULDBLOCK
+The file is locked and the
+.B LOCK_NB
+flag was selected.
+.SH VERSIONS
+Since Linux 2.0,
+.BR flock ()
+is implemented as a system call in its own right rather
+than being emulated in the GNU C library as a call to
+.BR fcntl (2).
+With this implementation,
+there is no interaction between the types of lock
+placed by
+.BR flock ()
+and
+.BR fcntl (2),
+and
+.BR flock ()
+does not detect deadlock.
+(Note, however, that on some systems, such as the modern BSDs,
+.\" E.g., according to the flock(2) man page, FreeBSD since at least 5.3
+.BR flock ()
+and
+.BR fcntl (2)
+locks
+.I do
+interact with one another.)
+.SS CIFS details
+Up to Linux 5.4,
+.BR flock ()
+is not propagated over SMB.
+A file with such locks will not appear locked for remote clients.
+.P
+Since Linux 5.5,
+.BR flock ()
+locks are emulated with SMB byte-range locks on the entire file.
+Similarly to NFS, this means that
+.BR fcntl (2)
+and
+.BR flock ()
+locks interact with one another.
+Another important side-effect is that the locks are not advisory anymore:
+any IO on a locked file will always fail with
+.B EACCES
+when done from a separate file descriptor.
+This difference originates from the design of locks in the SMB protocol,
+which provides mandatory locking semantics.
+.P
+Remote and mandatory locking semantics may vary with
+SMB protocol, mount options and server type.
+See
+.BR mount.cifs (8)
+for additional information.
+.SH STANDARDS
+BSD.
+.SH HISTORY
+4.4BSD (the
+.BR flock ()
+call first appeared in 4.2BSD).
+A version of
+.BR flock (),
+possibly implemented in terms of
+.BR fcntl (2),
+appears on most UNIX systems.
+.SS NFS details
+Up to Linux 2.6.11,
+.BR flock ()
+does not lock files over NFS
+(i.e., the scope of locks was limited to the local system).
+Instead, one could use
+.BR fcntl (2)
+byte-range locking, which does work over NFS,
+given a sufficiently recent version of
+Linux and a server which supports locking.
+.P
+Since Linux 2.6.12, NFS clients support
+.BR flock ()
+locks by emulating them as
+.BR fcntl (2)
+byte-range locks on the entire file.
+This means that
+.BR fcntl (2)
+and
+.BR flock ()
+locks
+.I do
+interact with one another over NFS.
+It also means that in order to place an exclusive lock,
+the file must be opened for writing.
+.P
+Since Linux 2.6.37,
+.\" commit 5eebde23223aeb0ad2d9e3be6590ff8bbfab0fc2
+the kernel supports a compatibility mode that allows
+.BR flock ()
+locks (and also
+.BR fcntl (2)
+byte region locks) to be treated as local;
+see the discussion of the
+.I "local_lock"
+option in
+.BR nfs (5).
+.SH NOTES
+.BR flock ()
+places advisory locks only; given suitable permissions on a file,
+a process is free to ignore the use of
+.BR flock ()
+and perform I/O on the file.
+.P
+.BR flock ()
+and
+.BR fcntl (2)
+locks have different semantics with respect to forked processes and
+.BR dup (2).
+On systems that implement
+.BR flock ()
+using
+.BR fcntl (2),
+the semantics of
+.BR flock ()
+will be different from those described in this manual page.
+.P
+Converting a lock
+(shared to exclusive, or vice versa) is not guaranteed to be atomic:
+the existing lock is first removed, and then a new lock is established.
+Between these two steps,
+a pending lock request by another process may be granted,
+with the result that the conversion either blocks, or fails if
+.B LOCK_NB
+was specified.
+(This is the original BSD behavior,
+and occurs on many other implementations.)
+.\" Kernel 2.5.21 changed things a little: during lock conversion
+.\" it is now the highest priority process that will get the lock -- mtk
+.SH SEE ALSO
+.BR flock (1),
+.BR close (2),
+.BR dup (2),
+.BR execve (2),
+.BR fcntl (2),
+.BR fork (2),
+.BR open (2),
+.BR lockf (3),
+.BR lslocks (8)
+.P
+.I Documentation/filesystems/locks.txt
+in the Linux kernel source tree
+.RI ( Documentation/locks.txt
+in older kernels)
diff --git a/man/man2/fork.2 b/man/man2/fork.2
new file mode 100644
index 000000000..b5a7816a0
--- /dev/null
+++ b/man/man2/fork.2
@@ -0,0 +1,348 @@
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" A few fragments remain from an earlier (1992) page by
+.\" Drew Eckhardt (drew@cs.colorado.edu),
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt (michael@moria.de)
+.\" Modified Sat Jul 24 13:22:07 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 21 Aug 1994 by Michael Chastain (mec@shell.portal.com):
+.\"   Referenced 'clone(2)'.
+.\" Modified 1995-06-10, 1996-04-18, 1999-11-01, 2000-12-24
+.\"   by Andries Brouwer (aeb@cwi.nl)
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" 2006-09-04, Michael Kerrisk
+.\"     Greatly expanded, to describe all attributes that differ
+.\"	parent and child.
+.\"
+.TH fork 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fork \- create a child process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B pid_t fork(void);
+.fi
+.SH DESCRIPTION
+.BR fork ()
+creates a new process by duplicating the calling process.
+The new process is referred to as the
+.I child
+process.
+The calling process is referred to as the
+.I parent
+process.
+.P
+The child process and the parent process run in separate memory spaces.
+At the time of
+.BR fork ()
+both memory spaces have the same content.
+Memory writes, file mappings
+.RB ( mmap (2)),
+and unmappings
+.RB ( munmap (2))
+performed by one of the processes do not affect the other.
+.P
+The child process is an exact duplicate of the parent
+process except for the following points:
+.IP \[bu] 3
+The child has its own unique process ID,
+and this PID does not match the ID of any existing process group
+.RB ( setpgid (2))
+or session.
+.IP \[bu]
+The child's parent process ID is the same as the parent's process ID.
+.IP \[bu]
+The child does not inherit its parent's memory locks
+.RB ( mlock (2),
+.BR mlockall (2)).
+.IP \[bu]
+Process resource utilizations
+.RB ( getrusage (2))
+and CPU time counters
+.RB ( times (2))
+are reset to zero in the child.
+.IP \[bu]
+The child's set of pending signals is initially empty
+.RB ( sigpending (2)).
+.IP \[bu]
+The child does not inherit semaphore adjustments from its parent
+.RB ( semop (2)).
+.IP \[bu]
+The child does not inherit process-associated record locks from its parent
+.RB ( fcntl (2)).
+(On the other hand, it does inherit
+.BR fcntl (2)
+open file description locks and
+.BR flock (2)
+locks from its parent.)
+.IP \[bu]
+The child does not inherit timers from its parent
+.RB ( setitimer (2),
+.BR alarm (2),
+.BR timer_create (2)).
+.IP \[bu]
+The child does not inherit outstanding asynchronous I/O operations
+from its parent
+.RB ( aio_read (3),
+.BR aio_write (3)),
+nor does it inherit any asynchronous I/O contexts from its parent (see
+.BR io_setup (2)).
+.P
+The process attributes in the preceding list are all specified
+in POSIX.1.
+The parent and child also differ with respect to the following
+Linux-specific process attributes:
+.IP \[bu] 3
+The child does not inherit directory change notifications (dnotify)
+from its parent
+(see the description of
+.B F_NOTIFY
+in
+.BR fcntl (2)).
+.IP \[bu]
+The
+.BR prctl (2)
+.B PR_SET_PDEATHSIG
+setting is reset so that the child does not receive a signal
+when its parent terminates.
+.IP \[bu]
+The default timer slack value is set to the parent's
+current timer slack value.
+See the description of
+.B PR_SET_TIMERSLACK
+in
+.BR prctl (2).
+.IP \[bu]
+Memory mappings that have been marked with the
+.BR madvise (2)
+.B MADV_DONTFORK
+flag are not inherited across a
+.BR fork ().
+.IP \[bu]
+Memory in address ranges that have been marked with the
+.BR madvise (2)
+.B MADV_WIPEONFORK
+flag is zeroed in the child after a
+.BR fork ().
+(The
+.B MADV_WIPEONFORK
+setting remains in place for those address ranges in the child.)
+.IP \[bu]
+The termination signal of the child is always
+.B SIGCHLD
+(see
+.BR clone (2)).
+.IP \[bu]
+The port access permission bits set by
+.BR ioperm (2)
+are not inherited by the child;
+the child must turn on any bits that it requires using
+.BR ioperm (2).
+.P
+Note the following further points:
+.IP \[bu] 3
+The child process is created with a single thread\[em]the
+one that called
+.BR fork ().
+The entire virtual address space of the parent is replicated in the child,
+including the states of mutexes, condition variables,
+and other pthreads objects; the use of
+.BR pthread_atfork (3)
+may be helpful for dealing with problems that this can cause.
+.IP \[bu]
+After a
+.BR fork ()
+in a multithreaded program,
+the child can safely call only async-signal-safe functions (see
+.BR signal\-safety (7))
+until such time as it calls
+.BR execve (2).
+.IP \[bu]
+The child inherits copies of the parent's set of open file descriptors.
+Each file descriptor in the child refers to the same
+open file description (see
+.BR open (2))
+as the corresponding file descriptor in the parent.
+This means that the two file descriptors share open file status flags,
+file offset,
+and signal-driven I/O attributes (see the description of
+.B F_SETOWN
+and
+.B F_SETSIG
+in
+.BR fcntl (2)).
+.IP \[bu]
+The child inherits copies of the parent's set of open message
+queue descriptors (see
+.BR mq_overview (7)).
+Each file descriptor in the child refers to the same
+open message queue description
+as the corresponding file descriptor in the parent.
+This means that the two file descriptors share the same flags
+.RI ( mq_flags ).
+.IP \[bu]
+The child inherits copies of the parent's set of open directory streams (see
+.BR opendir (3)).
+POSIX.1 says that the corresponding directory streams
+in the parent and child
+.I may
+share the directory stream positioning;
+on Linux/glibc they do not.
+.SH RETURN VALUE
+On success, the PID of the child process is returned in the parent,
+and 0 is returned in the child.
+On failure, \-1 is returned in the parent,
+no child process is created, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+.\" NOTE! The following should match the description in pthread_create(3)
+A system-imposed limit on the number of threads was encountered.
+There are a number of limits that may trigger this error:
+.RS
+.IP \[bu] 3
+the
+.B RLIMIT_NPROC
+soft resource limit (set via
+.BR setrlimit (2)),
+which limits the number of processes and threads for a real user ID,
+was reached;
+.IP \[bu]
+the kernel's system-wide limit on the number of processes and threads,
+.IR /proc/sys/kernel/threads\-max ,
+was reached (see
+.BR proc (5));
+.IP \[bu]
+the maximum number of PIDs,
+.IR /proc/sys/kernel/pid_max ,
+was reached (see
+.BR proc (5));
+or
+.IP \[bu]
+the PID limit
+.RI ( pids.max )
+imposed by the cgroup "process number" (PIDs) controller was reached.
+.RE
+.TP
+.B EAGAIN
+The caller is operating under the
+.B SCHED_DEADLINE
+scheduling policy and does not have the reset-on-fork flag set.
+See
+.BR sched (7).
+.TP
+.B ENOMEM
+.BR fork ()
+failed to allocate the necessary kernel structures because memory is tight.
+.TP
+.B ENOMEM
+An attempt was made to create a child process in a PID namespace
+whose "init" process has terminated.
+See
+.BR pid_namespaces (7).
+.TP
+.B ENOSYS
+.BR fork ()
+is not supported on this platform (for example,
+.\" e.g., arm (optionally), blackfin, c6x, frv, h8300, microblaze, xtensa
+hardware without a Memory-Management Unit).
+.TP
+.BR ERESTARTNOINTR " (since Linux 2.6.17)"
+.\" commit 4a2c7a7837da1b91468e50426066d988050e4d56
+System call was interrupted by a signal and will be restarted.
+(This can be seen only during a trace.)
+.SH VERSIONS
+.SS C library/kernel differences
+Since glibc 2.3.3,
+.\" nptl/sysdeps/unix/sysv/linux/fork.c
+rather than invoking the kernel's
+.BR fork ()
+system call,
+the glibc
+.BR fork ()
+wrapper that is provided as part of the
+NPTL threading implementation invokes
+.BR clone (2)
+with flags that provide the same effect as the traditional system call.
+(A call to
+.BR fork ()
+is equivalent to a call to
+.BR clone (2)
+specifying
+.I flags
+as just
+.BR SIGCHLD .)
+The glibc wrapper invokes any fork handlers that have been
+established using
+.BR pthread_atfork (3).
+.\" and does some magic to ensure that getpid(2) returns the right value.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH NOTES
+Under Linux,
+.BR fork ()
+is implemented using copy-on-write pages, so the only penalty that it incurs
+is the time and memory required to duplicate the parent's page tables,
+and to create a unique task structure for the child.
+.SH EXAMPLES
+See
+.BR pipe (2)
+and
+.BR wait (2)
+for more examples.
+.P
+.\" SRC BEGIN (fork.c)
+.EX
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(void)
+{
+    pid_t pid;
+\&
+    if (signal(SIGCHLD, SIG_IGN) == SIG_ERR) {
+        perror("signal");
+        exit(EXIT_FAILURE);
+    }
+    pid = fork();
+    switch (pid) {
+    case \-1:
+        perror("fork");
+        exit(EXIT_FAILURE);
+    case 0:
+        puts("Child exiting.");
+        exit(EXIT_SUCCESS);
+    default:
+        printf("Child is PID %jd\en", (intmax_t) pid);
+        puts("Parent exiting.");
+        exit(EXIT_SUCCESS);
+    }
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clone (2),
+.BR execve (2),
+.BR exit (2),
+.BR setrlimit (2),
+.BR unshare (2),
+.BR vfork (2),
+.BR wait (2),
+.BR daemon (3),
+.BR pthread_atfork (3),
+.BR capabilities (7),
+.BR credentials (7)
diff --git a/man/man2/free_hugepages.2 b/man/man2/free_hugepages.2
new file mode 100644
index 000000000..d4b906a97
--- /dev/null
+++ b/man/man2/free_hugepages.2
@@ -0,0 +1 @@
+.so man2/alloc_hugepages.2
diff --git a/man/man2/fremovexattr.2 b/man/man2/fremovexattr.2
new file mode 100644
index 000000000..38d01ccde
--- /dev/null
+++ b/man/man2/fremovexattr.2
@@ -0,0 +1 @@
+.so man2/removexattr.2
diff --git a/man/man2/fsetxattr.2 b/man/man2/fsetxattr.2
new file mode 100644
index 000000000..dc0780751
--- /dev/null
+++ b/man/man2/fsetxattr.2
@@ -0,0 +1 @@
+.so man2/setxattr.2
diff --git a/man/man2/fstat.2 b/man/man2/fstat.2
new file mode 100644
index 000000000..b1a86c195
--- /dev/null
+++ b/man/man2/fstat.2
@@ -0,0 +1 @@
+.so man2/stat.2
diff --git a/man/man2/fstat64.2 b/man/man2/fstat64.2
new file mode 100644
index 000000000..2b9971d2e
--- /dev/null
+++ b/man/man2/fstat64.2
@@ -0,0 +1 @@
+.so man2/fstat.2
diff --git a/man/man2/fstatat.2 b/man/man2/fstatat.2
new file mode 100644
index 000000000..b1a86c195
--- /dev/null
+++ b/man/man2/fstatat.2
@@ -0,0 +1 @@
+.so man2/stat.2
diff --git a/man/man2/fstatat64.2 b/man/man2/fstatat64.2
new file mode 100644
index 000000000..7791269e6
--- /dev/null
+++ b/man/man2/fstatat64.2
@@ -0,0 +1 @@
+.so man2/fstatat.2
diff --git a/man/man2/fstatfs.2 b/man/man2/fstatfs.2
new file mode 100644
index 000000000..923d3c0cc
--- /dev/null
+++ b/man/man2/fstatfs.2
@@ -0,0 +1 @@
+.so man2/statfs.2
diff --git a/man/man2/fstatfs64.2 b/man/man2/fstatfs64.2
new file mode 100644
index 000000000..fde2b22f5
--- /dev/null
+++ b/man/man2/fstatfs64.2
@@ -0,0 +1 @@
+.so man2/fstatfs.2
diff --git a/man/man2/fsync.2 b/man/man2/fsync.2
new file mode 100644
index 000000000..e8d19bcc8
--- /dev/null
+++ b/man/man2/fsync.2
@@ -0,0 +1,200 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu) and
+.\" and Copyright 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 21 Aug 1994 by Michael Chastain <mec@shell.portal.com>:
+.\"   Removed note about old libc (pre-4.5.26) translating to 'sync'.
+.\" Modified 15 Apr 1995 by Michael Chastain <mec@shell.portal.com>:
+.\"   Added `see also' section.
+.\" Modified 13 Apr 1996 by Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"   Added remarks about fdatasync.
+.\" Modified 31 Jan 1997 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 18 Apr 2001 by Andi Kleen
+.\"   Fix description to describe what it really does; add a few caveats.
+.\" 2006-04-28, mtk, substantial rewrite of various parts.
+.\" 2012-02-27 Various changes by Christoph Hellwig <hch@lst.de>
+.\"
+.TH fsync 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fsync, fdatasync \- synchronize a file's in-core state with storage device
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int fsync(int " fd );
+.P
+.BI "int fdatasync(int " fd );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.nf
+.BR fsync ():
+    glibc 2.16 and later:
+        No feature test macros need be defined
+    glibc up to and including 2.15:
+        _BSD_SOURCE || _XOPEN_SOURCE
+            || /* Since glibc 2.8: */ _POSIX_C_SOURCE >= 200112L
+.fi
+.P
+.BR fdatasync ():
+.nf
+    _POSIX_C_SOURCE >= 199309L || _XOPEN_SOURCE >= 500
+.fi
+.SH DESCRIPTION
+.BR fsync ()
+transfers ("flushes") all modified in-core data of
+(i.e., modified buffer cache pages for) the
+file referred to by the file descriptor
+.I fd
+to the disk device (or other permanent storage device) so that all
+changed information can be retrieved even if the system crashes or
+is rebooted.
+This includes writing through or flushing a disk cache if present.
+The call blocks until the device reports that the transfer has completed.
+.P
+As well as flushing the file data,
+.BR fsync ()
+also flushes the metadata information associated with the file (see
+.BR inode (7)).
+.P
+Calling
+.BR fsync ()
+does not necessarily ensure
+that the entry in the directory containing the file has also reached disk.
+For that an explicit
+.BR fsync ()
+on a file descriptor for the directory is also needed.
+.P
+.BR fdatasync ()
+is similar to
+.BR fsync (),
+but does not flush modified metadata unless that metadata
+is needed in order to allow a subsequent data retrieval to be
+correctly handled.
+For example, changes to
+.I st_atime
+or
+.I st_mtime
+(respectively, time of last access and
+time of last modification; see
+.BR inode (7))
+do not require flushing because they are not necessary for
+a subsequent data read to be handled correctly.
+On the other hand, a change to the file size
+.RI ( st_size ,
+as made by say
+.BR ftruncate (2)),
+would require a metadata flush.
+.P
+The aim of
+.BR fdatasync ()
+is to reduce disk activity for applications that do not
+require all metadata to be synchronized with the disk.
+.SH RETURN VALUE
+On success, these system calls return zero.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid open file descriptor.
+.TP
+.B EINTR
+The function was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EIO
+An error occurred during synchronization.
+This error may relate to data written to some other file descriptor
+on the same file.
+Since Linux 4.13,
+.\" commit 088737f44bbf6378745f5b57b035e57ee3dc4750
+errors from write-back will be reported to
+all file descriptors that might have written the data which triggered
+the error.
+Some filesystems (e.g., NFS) keep close track of which data
+came through which file descriptor, and give more precise reporting.
+Other filesystems (e.g., most local filesystems) will report errors to
+all file descriptors that were open on the file when the error was recorded.
+.TP
+.B ENOSPC
+Disk space was exhausted while synchronizing.
+.TP
+.B EROFS
+.TQ
+.B EINVAL
+.I fd
+is bound to a special file (e.g., a pipe, FIFO, or socket)
+which does not support synchronization.
+.TP
+.B ENOSPC
+.TQ
+.B EDQUOT
+.I fd
+is bound to a file on NFS or another filesystem which does not allocate
+space at the time of a
+.BR write (2)
+system call, and some previous write failed due to insufficient
+storage space.
+.SH VERSIONS
+On POSIX systems on which
+.BR fdatasync ()
+is available,
+.B _POSIX_SYNCHRONIZED_IO
+is defined in
+.I <unistd.h>
+to a value greater than 0.
+(See also
+.BR sysconf (3).)
+.\" POSIX.1-2001: It shall be defined to -1 or 0 or 200112L.
+.\" -1: unavailable, 0: ask using sysconf().
+.\" glibc defines them to 1.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.2BSD.
+.P
+In Linux 2.2 and earlier,
+.BR fdatasync ()
+is equivalent to
+.BR fsync (),
+and so has no performance advantage.
+.P
+The
+.BR fsync ()
+implementations in older kernels and lesser used filesystems
+do not know how to flush disk caches.
+In these cases disk caches need to be disabled using
+.BR hdparm (8)
+or
+.BR sdparm (8)
+to guarantee safe operation.
+.P
+Under AT&T UNIX System V Release 4
+.I fd
+needs to be opened for writing.
+This is by itself incompatible with the original BSD interface
+and forbidden by POSIX,
+but nevertheless survives in HP-UX and AIX.
+.SH SEE ALSO
+.BR sync (1),
+.BR bdflush (2),
+.BR open (2),
+.BR posix_fadvise (2),
+.BR pwritev (2),
+.BR sync (2),
+.BR sync_file_range (2),
+.BR fflush (3),
+.BR fileno (3),
+.BR hdparm (8),
+.BR mount (8)
diff --git a/man/man2/ftruncate.2 b/man/man2/ftruncate.2
new file mode 100644
index 000000000..2ed34f1ed
--- /dev/null
+++ b/man/man2/ftruncate.2
@@ -0,0 +1 @@
+.so man2/truncate.2
diff --git a/man/man2/ftruncate64.2 b/man/man2/ftruncate64.2
new file mode 100644
index 000000000..a8862d3ea
--- /dev/null
+++ b/man/man2/ftruncate64.2
@@ -0,0 +1 @@
+.so man2/ftruncate.2
diff --git a/man/man2/futex.2 b/man/man2/futex.2
new file mode 100644
index 000000000..3eed74412
--- /dev/null
+++ b/man/man2/futex.2
@@ -0,0 +1,1976 @@
+.\" Page by b.hubert
+.\" and Copyright (C) 2015, Thomas Gleixner <tglx@linutronix.de>
+.\" and Copyright (C) 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE)
+.\" may be freely modified and distributed
+.\" %%%LICENSE_END
+.\"
+.\" Niki A. Rahimi (LTC Security Development, narahimi@us.ibm.com)
+.\" added ERRORS section.
+.\"
+.\" Modified 2004-06-17 mtk
+.\" Modified 2004-10-07 aeb, added FUTEX_REQUEUE, FUTEX_CMP_REQUEUE
+.\"
+.\" FIXME Still to integrate are some points from Torvald Riegel's mail of
+.\" 2015-01-23:
+.\"       http://thread.gmane.org/gmane.linux.kernel/1703405/focus=7977
+.\"
+.\" FIXME Do we need to add some text regarding Torvald Riegel's 2015-01-24 mail
+.\"       http://thread.gmane.org/gmane.linux.kernel/1703405/focus=1873242
+.\"
+.TH futex 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+futex \- fast user-space locking
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.P
+.BR "#include <linux/futex.h>" "      /* Definition of " FUTEX_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(SYS_futex, uint32_t *" uaddr ", int " futex_op \
+", uint32_t " val ,
+.BI "             const struct timespec *" timeout , \
+" \fR  /* or: \fBuint32_t \fIval2\fP */"
+.BI "             uint32_t *" uaddr2 ", uint32_t " val3 );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR futex (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR futex ()
+system call provides a method for waiting until a certain condition becomes
+true.
+It is typically used as a blocking construct in the context of
+shared-memory synchronization.
+When using futexes, the majority of
+the synchronization operations are performed in user space.
+A user-space program employs the
+.BR futex ()
+system call only when it is likely that the program has to block for
+a longer time until the condition becomes true.
+Other
+.BR futex ()
+operations can be used to wake any processes or threads waiting
+for a particular condition.
+.P
+A futex is a 32-bit value\[em]referred to below as a
+.IR "futex word" \[em]whose
+address is supplied to the
+.BR futex ()
+system call.
+(Futexes are 32 bits in size on all platforms, including 64-bit systems.)
+All futex operations are governed by this value.
+In order to share a futex between processes,
+the futex is placed in a region of shared memory,
+created using (for example)
+.BR mmap (2)
+or
+.BR shmat (2).
+(Thus, the futex word may have different
+virtual addresses in different processes,
+but these addresses all refer to the same location in physical memory.)
+In a multithreaded program, it is sufficient to place the futex word
+in a global variable shared by all threads.
+.P
+When executing a futex operation that requests to block a thread,
+the kernel will block only if the futex word has the value that the
+calling thread supplied (as one of the arguments of the
+.BR futex ()
+call) as the expected value of the futex word.
+The loading of the futex word's value,
+the comparison of that value with the expected value,
+and the actual blocking will happen atomically and will be totally ordered
+with respect to concurrent operations performed by other threads
+on the same futex word.
+.\" Notes from Darren Hart (Dec 2015):
+.\"     Totally ordered with respect futex operations refers to semantics
+.\"     of the ACQUIRE/RELEASE operations and how they impact ordering of
+.\"     memory reads and writes. The kernel futex operations are protected
+.\"     by spinlocks, which ensure that all operations are serialized
+.\"     with respect to one another.
+.\"
+.\"     This is a lot to attempt to define in this document. Perhaps a
+.\"     reference to linux/Documentation/memory-barriers.txt as a footnote
+.\"     would be sufficient? Or perhaps for this manual, "serialized" would
+.\"     be sufficient, with a footnote regarding "totally ordered" and a
+.\"     pointer to the memory-barrier documentation?
+Thus, the futex word is used to connect the synchronization in user space
+with the implementation of blocking by the kernel.
+Analogously to an atomic
+compare-and-exchange operation that potentially changes shared memory,
+blocking via a futex is an atomic compare-and-block operation.
+.\" FIXME(Torvald Riegel):
+.\" Eventually we want to have some text in NOTES to satisfy
+.\" the reference in the following sentence
+.\"     See NOTES for a detailed specification of
+.\"     the synchronization semantics.
+.P
+One use of futexes is for implementing locks.
+The state of the lock (i.e., acquired or not acquired)
+can be represented as an atomically accessed flag in shared memory.
+In the uncontended case,
+a thread can access or modify the lock state with atomic instructions,
+for example atomically changing it from not acquired to acquired
+using an atomic compare-and-exchange instruction.
+(Such instructions are performed entirely in user mode,
+and the kernel maintains no information about the lock state.)
+On the other hand, a thread may be unable to acquire a lock because
+it is already acquired by another thread.
+It then may pass the lock's flag as a futex word and the value
+representing the acquired state as the expected value to a
+.BR futex ()
+wait operation.
+This
+.BR futex ()
+operation will block if and only if the lock is still acquired
+(i.e., the value in the futex word still matches the "acquired state").
+When releasing the lock, a thread has to first reset the
+lock state to not acquired and then execute a futex
+operation that wakes threads blocked on the lock flag used as a futex word
+(this can be further optimized to avoid unnecessary wake-ups).
+See
+.BR futex (7)
+for more detail on how to use futexes.
+.P
+Besides the basic wait and wake-up futex functionality, there are further
+futex operations aimed at supporting more complex use cases.
+.P
+Note that
+no explicit initialization or destruction is necessary to use futexes;
+the kernel maintains a futex
+(i.e., the kernel-internal implementation artifact)
+only while operations such as
+.BR FUTEX_WAIT ,
+described below, are being performed on a particular futex word.
+.\"
+.SS Arguments
+The
+.I uaddr
+argument points to the futex word.
+On all platforms, futexes are four-byte
+integers that must be aligned on a four-byte boundary.
+The operation to perform on the futex is specified in the
+.I futex_op
+argument;
+.I val
+is a value whose meaning and purpose depends on
+.IR futex_op .
+.P
+The remaining arguments
+.RI ( timeout ,
+.IR uaddr2 ,
+and
+.IR val3 )
+are required only for certain of the futex operations described below.
+Where one of these arguments is not required, it is ignored.
+.P
+For several blocking operations, the
+.I timeout
+argument is a pointer to a
+.I timespec
+structure that specifies a timeout for the operation.
+However,  notwithstanding the prototype shown above, for some operations,
+the least significant four bytes of this argument are instead
+used as an integer whose meaning is determined by the operation.
+For these operations, the kernel casts the
+.I timeout
+value first to
+.IR "unsigned long",
+then to
+.IR uint32_t ,
+and in the remainder of this page, this argument is referred to as
+.I val2
+when interpreted in this fashion.
+.P
+Where it is required, the
+.I uaddr2
+argument is a pointer to a second futex word that is employed
+by the operation.
+.P
+The interpretation of the final integer argument,
+.IR val3 ,
+depends on the operation.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SS Futex operations
+The
+.I futex_op
+argument consists of two parts:
+a command that specifies the operation to be performed,
+bitwise ORed with zero or more options that
+modify the behaviour of the operation.
+The options that may be included in
+.I futex_op
+are as follows:
+.TP
+.BR FUTEX_PRIVATE_FLAG " (since Linux 2.6.22)"
+.\" commit 34f01cc1f512fa783302982776895c73714ebbc2
+This option bit can be employed with all futex operations.
+It tells the kernel that the futex is process-private and not shared
+with another process (i.e., it is being used for synchronization
+only between threads of the same process).
+This allows the kernel to make some additional performance optimizations.
+.\" I.e., It allows the kernel choose the fast path for validating
+.\" the user-space address and avoids expensive VMA lookups,
+.\" taking reference counts on file backing store, and so on.
+.IP
+As a convenience,
+.I <linux/futex.h>
+defines a set of constants with the suffix
+.B _PRIVATE
+that are equivalents of all of the operations listed below,
+.\" except the obsolete FUTEX_FD, for which the "private" flag was
+.\" meaningless
+but with the
+.B FUTEX_PRIVATE_FLAG
+ORed into the constant value.
+Thus, there are
+.BR FUTEX_WAIT_PRIVATE ,
+.BR FUTEX_WAKE_PRIVATE ,
+and so on.
+.TP
+.BR FUTEX_CLOCK_REALTIME " (since Linux 2.6.28)"
+.\" commit 1acdac104668a0834cfa267de9946fac7764d486
+This option bit can be employed only with the
+.BR FUTEX_WAIT_BITSET ,
+.BR FUTEX_WAIT_REQUEUE_PI ,
+(since Linux 4.5)
+.\" commit 337f13046ff03717a9e99675284a817527440a49
+.BR FUTEX_WAIT ,
+and
+(since Linux 5.14)
+.\" commit bf22a6976897977b0a3f1aeba6823c959fc4fdae
+.B FUTEX_LOCK_PI2
+operations.
+.IP
+If this option is set, the kernel measures the
+.I timeout
+against the
+.B CLOCK_REALTIME
+clock.
+.IP
+If this option is not set, the kernel measures the
+.I timeout
+against the
+.B CLOCK_MONOTONIC
+clock.
+.P
+The operation specified in
+.I futex_op
+is one of the following:
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_WAIT " (since Linux 2.6.0)"
+.\" Strictly speaking, since some time in Linux 2.5.x
+This operation tests that the value at the
+futex word pointed to by the address
+.I uaddr
+still contains the expected value
+.IR val ,
+and if so, then sleeps waiting for a
+.B FUTEX_WAKE
+operation on the futex word.
+The load of the value of the futex word is an atomic memory
+access (i.e., using atomic machine instructions of the respective
+architecture).
+This load, the comparison with the expected value, and
+starting to sleep are performed atomically
+.\" FIXME: Torvald, I think we may need to add some explanation of
+.\" "totally ordered" here.
+and totally ordered
+with respect to other futex operations on the same futex word.
+If the thread starts to sleep,
+it is considered a waiter on this futex word.
+If the futex value does not match
+.IR val ,
+then the call fails immediately with the error
+.BR EAGAIN .
+.IP
+The purpose of the comparison with the expected value is to prevent lost
+wake-ups.
+If another thread changed the value of the futex word after the
+calling thread decided to block based on the prior value,
+and if the other thread executed a
+.B FUTEX_WAKE
+operation (or similar wake-up) after the value change and before this
+.B FUTEX_WAIT
+operation, then the calling thread will observe the
+value change and will not start to sleep.
+.IP
+If the
+.I timeout
+is not NULL, the structure it points to specifies a
+timeout for the wait.
+(This interval will be rounded up to the system clock granularity,
+and is guaranteed not to expire early.)
+The timeout is by default measured according to the
+.B CLOCK_MONOTONIC
+clock, but, since Linux 4.5, the
+.B CLOCK_REALTIME
+clock can be selected by specifying
+.B FUTEX_CLOCK_REALTIME
+in
+.IR futex_op .
+If
+.I timeout
+is NULL, the call blocks indefinitely.
+.IP
+.IR Note :
+for
+.BR FUTEX_WAIT ,
+.I timeout
+is interpreted as a
+.I relative
+value.
+This differs from other futex operations, where
+.I timeout
+is interpreted as an absolute value.
+To obtain the equivalent of
+.B FUTEX_WAIT
+with an absolute timeout, employ
+.B FUTEX_WAIT_BITSET
+with
+.I val3
+specified as
+.BR FUTEX_BITSET_MATCH_ANY .
+.IP
+The arguments
+.I uaddr2
+and
+.I val3
+are ignored.
+.\" FIXME . (Torvald) I think we should remove this.  Or maybe adapt to a
+.\" different example.
+.\"
+.\"     For
+.\"     .BR futex (7),
+.\"     this call is executed if decrementing the count gave a negative value
+.\"     (indicating contention),
+.\"     and will sleep until another process or thread releases
+.\"     the futex and executes the
+.\"     .B FUTEX_WAKE
+.\"     operation.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_WAKE " (since Linux 2.6.0)"
+.\" Strictly speaking, since Linux 2.5.x
+This operation wakes at most
+.I val
+of the waiters that are waiting (e.g., inside
+.BR FUTEX_WAIT )
+on the futex word at the address
+.IR uaddr .
+Most commonly,
+.I val
+is specified as either 1 (wake up a single waiter) or
+.B INT_MAX
+(wake up all waiters).
+No guarantee is provided about which waiters are awoken
+(e.g., a waiter with a higher scheduling priority is not guaranteed
+to be awoken in preference to a waiter with a lower priority).
+.IP
+The arguments
+.IR timeout ,
+.IR uaddr2 ,
+and
+.I val3
+are ignored.
+.\" FIXME . (Torvald) I think we should remove this.  Or maybe adapt to
+.\" a different example.
+.\"
+.\"     For
+.\"     .BR futex (7),
+.\"     this is executed if incrementing the count showed that
+.\"     there were waiters,
+.\"     once the futex value has been set to 1
+.\"     (indicating that it is available).
+.\"
+.\" How does "incrementing the count show that there were waiters"?
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_FD " (from Linux 2.6.0 up to and including Linux 2.6.25)"
+.\" Strictly speaking, from Linux 2.5.x to Linux 2.6.25
+This operation creates a file descriptor that is associated with
+the futex at
+.IR uaddr .
+The caller must close the returned file descriptor after use.
+When another process or thread performs a
+.B FUTEX_WAKE
+on the futex word, the file descriptor indicates as being readable with
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7)
+.IP
+The file descriptor can be used to obtain asynchronous notifications: if
+.I val
+is nonzero, then, when another process or thread executes a
+.BR FUTEX_WAKE ,
+the caller will receive the signal number that was passed in
+.IR val .
+.IP
+The arguments
+.IR timeout ,
+.IR uaddr2 ,
+and
+.I val3
+are ignored.
+.IP
+Because it was inherently racy,
+.B FUTEX_FD
+has been removed
+.\" commit 82af7aca56c67061420d618cc5a30f0fd4106b80
+from Linux 2.6.26 onward.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_REQUEUE " (since Linux 2.6.0)"
+This operation performs the same task as
+.B FUTEX_CMP_REQUEUE
+(see below), except that no check is made using the value in
+.IR  val3 .
+(The argument
+.I val3
+is ignored.)
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_CMP_REQUEUE " (since Linux 2.6.7)"
+This operation first checks whether the location
+.I uaddr
+still contains the value
+.IR val3 .
+If not, the operation fails with the error
+.BR EAGAIN .
+Otherwise, the operation wakes up a maximum of
+.I val
+waiters that are waiting on the futex at
+.IR uaddr .
+If there are more than
+.I val
+waiters, then the remaining waiters are removed
+from the wait queue of the source futex at
+.I uaddr
+and added to the wait queue of the target futex at
+.IR uaddr2 .
+The
+.I val2
+argument specifies an upper limit on the number of waiters
+that are requeued to the futex at
+.IR uaddr2 .
+.IP
+.\" FIXME(Torvald) Is the following correct?  Or is just the decision
+.\" which threads to wake or requeue part of the atomic operation?
+The load from
+.I uaddr
+is an atomic memory access (i.e., using atomic machine instructions of
+the respective architecture).
+This load, the comparison with
+.IR val3 ,
+and the requeueing of any waiters are performed atomically and totally
+ordered with respect to other operations on the same futex word.
+.\" Notes from a f2f conversation with Thomas Gleixner (Aug 2015): ###
+.\"	The operation is serialized with respect to operations on both
+.\"	source and target futex. No other waiter can enqueue itself
+.\"	for waiting and no other waiter can dequeue itself because of
+.\"	a timeout or signal.
+.IP
+Typical values to specify for
+.I val
+are 0 or 1.
+(Specifying
+.B INT_MAX
+is not useful, because it would make the
+.B FUTEX_CMP_REQUEUE
+operation equivalent to
+.BR FUTEX_WAKE .)
+The limit value specified via
+.I val2
+is typically either 1 or
+.BR INT_MAX .
+(Specifying the argument as 0 is not useful, because it would make the
+.B FUTEX_CMP_REQUEUE
+operation equivalent to
+.BR FUTEX_WAIT .)
+.IP
+The
+.B FUTEX_CMP_REQUEUE
+operation was added as a replacement for the earlier
+.BR FUTEX_REQUEUE .
+The difference is that the check of the value at
+.I uaddr
+can be used to ensure that requeueing happens only under certain
+conditions, which allows race conditions to be avoided in certain use cases.
+.\" But, as Rich Felker points out, there remain valid use cases for
+.\" FUTEX_REQUEUE, for example, when the calling thread is requeuing
+.\" the target(s) to a lock that the calling thread owns
+.\"     From: Rich Felker <dalias@libc.org>
+.\"     Date: Wed, 29 Oct 2014 22:43:17 -0400
+.\"     To: Darren Hart <dvhart@infradead.org>
+.\"     CC: libc-alpha@sourceware.org, ...
+.\"     Subject: Re: Add futex wrapper to glibc?
+.IP
+Both
+.B FUTEX_REQUEUE
+and
+.B FUTEX_CMP_REQUEUE
+can be used to avoid "thundering herd" wake-ups that could occur when using
+.B FUTEX_WAKE
+in cases where all of the waiters that are woken need to acquire
+another futex.
+Consider the following scenario,
+where multiple waiter threads are waiting on B,
+a wait queue implemented using a futex:
+.IP
+.in +4n
+.EX
+lock(A)
+while (!check_value(V)) {
+    unlock(A);
+    block_on(B);
+    lock(A);
+};
+unlock(A);
+.EE
+.in
+.IP
+If a waker thread used
+.BR FUTEX_WAKE ,
+then all waiters waiting on B would be woken up,
+and they would all try to acquire lock A.
+However, waking all of the threads in this manner would be pointless because
+all except one of the threads would immediately block on lock A again.
+By contrast, a requeue operation wakes just one waiter and moves
+the other waiters to lock A,
+and when the woken waiter unlocks A then the next waiter can proceed.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_WAKE_OP " (since Linux 2.6.14)"
+.\" commit 4732efbeb997189d9f9b04708dc26bf8613ed721
+.\"	Author: Jakub Jelinek <jakub@redhat.com>
+.\"	Date:   Tue Sep 6 15:16:25 2005 -0700
+.\" FIXME. (Torvald) The glibc condvar implementation is currently being
+.\"     revised (e.g., to not use an internal lock anymore).
+.\"     It is probably more future-proof to remove this paragraph.
+.\" [Torvald, do you have an update here?]
+This operation was added to support some user-space use cases
+where more than one futex must be handled at the same time.
+The most notable example is the implementation of
+.BR pthread_cond_signal (3),
+which requires operations on two futexes,
+the one used to implement the mutex and the one used in the implementation
+of the wait queue associated with the condition variable.
+.B FUTEX_WAKE_OP
+allows such cases to be implemented without leading to
+high rates of contention and context switching.
+.IP
+The
+.B FUTEX_WAKE_OP
+operation is equivalent to executing the following code atomically
+and totally ordered with respect to other futex operations on
+any of the two supplied futex words:
+.IP
+.in +4n
+.EX
+uint32_t oldval = *(uint32_t *) uaddr2;
+*(uint32_t *) uaddr2 = oldval \fIop\fP \fIoparg\fP;
+futex(uaddr, FUTEX_WAKE, val, 0, 0, 0);
+if (oldval \fIcmp\fP \fIcmparg\fP)
+    futex(uaddr2, FUTEX_WAKE, val2, 0, 0, 0);
+.EE
+.in
+.IP
+In other words,
+.B FUTEX_WAKE_OP
+does the following:
+.RS
+.IP \[bu] 3
+saves the original value of the futex word at
+.I uaddr2
+and performs an operation to modify the value of the futex at
+.IR uaddr2 ;
+this is an atomic read-modify-write memory access (i.e., using atomic
+machine instructions of the respective architecture)
+.IP \[bu]
+wakes up a maximum of
+.I val
+waiters on the futex for the futex word at
+.IR uaddr ;
+and
+.IP \[bu]
+dependent on the results of a test of the original value of the
+futex word at
+.IR uaddr2 ,
+wakes up a maximum of
+.I val2
+waiters on the futex for the futex word at
+.IR uaddr2 .
+.RE
+.IP
+The operation and comparison that are to be performed are encoded
+in the bits of the argument
+.IR val3 .
+Pictorially, the encoding is:
+.IP
+.in +4n
+.EX
++---+---+-----------+-----------+
+|op |cmp|   oparg   |  cmparg   |
++---+---+-----------+-----------+
+  4   4       12          12    <== # of bits
+.EE
+.in
+.IP
+Expressed in code, the encoding is:
+.IP
+.in +4n
+.EX
+#define FUTEX_OP(op, oparg, cmp, cmparg) \e
+                (((op & 0xf) << 28) | \e
+                ((cmp & 0xf) << 24) | \e
+                ((oparg & 0xfff) << 12) | \e
+                (cmparg & 0xfff))
+.EE
+.in
+.IP
+In the above,
+.I op
+and
+.I cmp
+are each one of the codes listed below.
+The
+.I oparg
+and
+.I cmparg
+components are literal numeric values, except as noted below.
+.IP
+The
+.I op
+component has one of the following values:
+.IP
+.in +4n
+.EX
+FUTEX_OP_SET        0  /* uaddr2 = oparg; */
+FUTEX_OP_ADD        1  /* uaddr2 += oparg; */
+FUTEX_OP_OR         2  /* uaddr2 |= oparg; */
+FUTEX_OP_ANDN       3  /* uaddr2 &= \[ti]oparg; */
+FUTEX_OP_XOR        4  /* uaddr2 \[ha]= oparg; */
+.EE
+.in
+.IP
+In addition, bitwise ORing the following value into
+.I op
+causes
+.I (1\~<<\~oparg)
+to be used as the operand:
+.IP
+.in +4n
+.EX
+FUTEX_OP_ARG_SHIFT  8  /* Use (1 << oparg) as operand */
+.EE
+.in
+.IP
+The
+.I cmp
+field is one of the following:
+.IP
+.in +4n
+.EX
+FUTEX_OP_CMP_EQ     0  /* if (oldval == cmparg) wake */
+FUTEX_OP_CMP_NE     1  /* if (oldval != cmparg) wake */
+FUTEX_OP_CMP_LT     2  /* if (oldval < cmparg) wake */
+FUTEX_OP_CMP_LE     3  /* if (oldval <= cmparg) wake */
+FUTEX_OP_CMP_GT     4  /* if (oldval > cmparg) wake */
+FUTEX_OP_CMP_GE     5  /* if (oldval >= cmparg) wake */
+.EE
+.in
+.IP
+The return value of
+.B FUTEX_WAKE_OP
+is the sum of the number of waiters woken on the futex
+.I uaddr
+plus the number of waiters woken on the futex
+.IR uaddr2 .
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_WAIT_BITSET " (since Linux 2.6.25)"
+.\" commit cd689985cf49f6ff5c8eddc48d98b9d581d9475d
+This operation is like
+.B FUTEX_WAIT
+except that
+.I val3
+is used to provide a 32-bit bit mask to the kernel.
+This bit mask, in which at least one bit must be set,
+is stored in the kernel-internal state of the waiter.
+See the description of
+.B FUTEX_WAKE_BITSET
+for further details.
+.IP
+If
+.I timeout
+is not NULL, the structure it points to specifies
+an absolute timeout for the wait operation.
+If
+.I timeout
+is NULL, the operation can block indefinitely.
+.IP
+The
+.I uaddr2
+argument is ignored.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_WAKE_BITSET " (since Linux 2.6.25)"
+.\" commit cd689985cf49f6ff5c8eddc48d98b9d581d9475d
+This operation is the same as
+.B FUTEX_WAKE
+except that the
+.I val3
+argument is used to provide a 32-bit bit mask to the kernel.
+This bit mask, in which at least one bit must be set,
+is used to select which waiters should be woken up.
+The selection is done by a bitwise AND of the "wake" bit mask
+(i.e., the value in
+.IR val3 )
+and the bit mask which is stored in the kernel-internal
+state of the waiter (the "wait" bit mask that is set using
+.BR FUTEX_WAIT_BITSET ).
+All of the waiters for which the result of the AND is nonzero are woken up;
+the remaining waiters are left sleeping.
+.IP
+The effect of
+.B FUTEX_WAIT_BITSET
+and
+.B FUTEX_WAKE_BITSET
+is to allow selective wake-ups among multiple waiters that are blocked
+on the same futex.
+However, note that, depending on the use case,
+employing this bit-mask multiplexing feature on a
+futex can be less efficient than simply using multiple futexes,
+because employing bit-mask multiplexing requires the kernel
+to check all waiters on a futex,
+including those that are not interested in being woken up
+(i.e., they do not have the relevant bit set in their "wait" bit mask).
+.\" According to http://locklessinc.com/articles/futex_cheat_sheet/:
+.\"
+.\"    "The original reason for the addition of these extensions
+.\"     was to improve the performance of pthread read-write locks
+.\"     in glibc. However, the pthreads library no longer uses the
+.\"     same locking algorithm, and these extensions are not used
+.\"     without the bitset parameter being all ones.
+.\"
+.\" The page goes on to note that the FUTEX_WAIT_BITSET operation
+.\" is nevertheless used (with a bit mask of all ones) in order to
+.\" obtain the absolute timeout functionality that is useful
+.\" for efficiently implementing Pthreads APIs (which use absolute
+.\" timeouts); FUTEX_WAIT provides only relative timeouts.
+.IP
+The constant
+.BR FUTEX_BITSET_MATCH_ANY ,
+which corresponds to all 32 bits set in the bit mask, can be used as the
+.I val3
+argument for
+.B FUTEX_WAIT_BITSET
+and
+.BR FUTEX_WAKE_BITSET .
+Other than differences in the handling of the
+.I timeout
+argument, the
+.B FUTEX_WAIT
+operation is equivalent to
+.B FUTEX_WAIT_BITSET
+with
+.I val3
+specified as
+.BR FUTEX_BITSET_MATCH_ANY ;
+that is, allow a wake-up by any waker.
+The
+.B FUTEX_WAKE
+operation is equivalent to
+.B FUTEX_WAKE_BITSET
+with
+.I val3
+specified as
+.BR FUTEX_BITSET_MATCH_ANY ;
+that is, wake up any waiter(s).
+.IP
+The
+.I uaddr2
+and
+.I timeout
+arguments are ignored.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SS Priority-inheritance futexes
+Linux supports priority-inheritance (PI) futexes in order to handle
+priority-inversion problems that can be encountered with
+normal futex locks.
+Priority inversion is the problem that occurs when a high-priority
+task is blocked waiting to acquire a lock held by a low-priority task,
+while tasks at an intermediate priority continuously preempt
+the low-priority task from the CPU.
+Consequently, the low-priority task makes no progress toward
+releasing the lock, and the high-priority task remains blocked.
+.P
+Priority inheritance is a mechanism for dealing with
+the priority-inversion problem.
+With this mechanism, when a high-priority task becomes blocked
+by a lock held by a low-priority task,
+the priority of the low-priority task is temporarily raised
+to that of the high-priority task,
+so that it is not preempted by any intermediate level tasks,
+and can thus make progress toward releasing the lock.
+To be effective, priority inheritance must be transitive,
+meaning that if a high-priority task blocks on a lock
+held by a lower-priority task that is itself blocked by a lock
+held by another intermediate-priority task
+(and so on, for chains of arbitrary length),
+then both of those tasks
+(or more generally, all of the tasks in a lock chain)
+have their priorities raised to be the same as the high-priority task.
+.P
+From a user-space perspective,
+what makes a futex PI-aware is a policy agreement (described below)
+between user space and the kernel about the value of the futex word,
+coupled with the use of the PI-futex operations described below.
+(Unlike the other futex operations described above,
+the PI-futex operations are designed
+for the implementation of very specific IPC mechanisms.)
+.\"
+.\" Quoting Darren Hart:
+.\"     These opcodes paired with the PI futex value policy (described below)
+.\"     defines a "futex" as PI aware. These were created very specifically
+.\"     in support of PI pthread_mutexes, so it makes a lot more sense to
+.\"     talk about a PI aware pthread_mutex, than a PI aware futex, since
+.\"     there is a lot of policy and scaffolding that has to be built up
+.\"     around it to use it properly (this is what a PI pthread_mutex is).
+.P
+.\"       mtk: The following text is drawn from the Hart/Guniguntala paper
+.\"       (listed in SEE ALSO), but I have reworded some pieces
+.\"       significantly.
+.\"
+The PI-futex operations described below differ from the other
+futex operations in that they impose policy on the use of the value of the
+futex word:
+.IP \[bu] 3
+If the lock is not acquired, the futex word's value shall be 0.
+.IP \[bu]
+If the lock is acquired, the futex word's value shall
+be the thread ID (TID;
+see
+.BR gettid (2))
+of the owning thread.
+.IP \[bu]
+If the lock is owned and there are threads contending for the lock,
+then the
+.B FUTEX_WAITERS
+bit shall be set in the futex word's value; in other words, this value is:
+.IP
+.in +4n
+.EX
+FUTEX_WAITERS | TID
+.EE
+.in
+.IP
+(Note that is invalid for a PI futex word to have no owner and
+.B FUTEX_WAITERS
+set.)
+.P
+With this policy in place,
+a user-space application can acquire an unacquired
+lock or release a lock using atomic instructions executed in user mode
+(e.g., a compare-and-swap operation such as
+.I cmpxchg
+on the x86 architecture).
+Acquiring a lock simply consists of using compare-and-swap to atomically
+set the futex word's value to the caller's TID if its previous value was 0.
+Releasing a lock requires using compare-and-swap to set the futex word's
+value to 0 if the previous value was the expected TID.
+.P
+If a futex is already acquired (i.e., has a nonzero value),
+waiters must employ the
+.B FUTEX_LOCK_PI
+or
+.B FUTEX_LOCK_PI2
+operations to acquire the lock.
+If other threads are waiting for the lock, then the
+.B FUTEX_WAITERS
+bit is set in the futex value;
+in this case, the lock owner must employ the
+.B FUTEX_UNLOCK_PI
+operation to release the lock.
+.P
+In the cases where callers are forced into the kernel
+(i.e., required to perform a
+.BR futex ()
+call),
+they then deal directly with a so-called RT-mutex,
+a kernel locking mechanism which implements the required
+priority-inheritance semantics.
+After the RT-mutex is acquired, the futex value is updated accordingly,
+before the calling thread returns to user space.
+.P
+It is important to note
+.\" tglx (July 2015):
+.\"     If there are multiple waiters on a pi futex then a wake pi operation
+.\"     will wake the first waiter and hand over the lock to this waiter. This
+.\"     includes handing over the rtmutex which represents the futex in the
+.\"     kernel. The strict requirement is that the futex owner and the rtmutex
+.\"     owner must be the same, except for the update period which is
+.\"     serialized by the futex internal locking. That means the kernel must
+.\"     update the user-space value prior to returning to user space
+that the kernel will update the futex word's value prior
+to returning to user space.
+(This prevents the possibility of the futex word's value ending
+up in an invalid state, such as having an owner but the value being 0,
+or having waiters but not having the
+.B FUTEX_WAITERS
+bit set.)
+.P
+If a futex has an associated RT-mutex in the kernel
+(i.e., there are blocked waiters)
+and the owner of the futex/RT-mutex dies unexpectedly,
+then the kernel cleans up the RT-mutex and hands it over to the next waiter.
+This in turn requires that the user-space value is updated accordingly.
+To indicate that this is required, the kernel sets the
+.B FUTEX_OWNER_DIED
+bit in the futex word along with the thread ID of the new owner.
+User space can detect this situation via the presence of the
+.B FUTEX_OWNER_DIED
+bit and is then responsible for cleaning up the stale state left over by
+the dead owner.
+.\" tglx (July 2015):
+.\"     The FUTEX_OWNER_DIED bit can also be set on uncontended futexes, where
+.\"     the kernel has no state associated. This happens via the robust futex
+.\"     mechanism. In that case the futex value will be set to
+.\"     FUTEX_OWNER_DIED. The robust futex mechanism is also available for non
+.\"     PI futexes.
+.P
+PI futexes are operated on by specifying one of the values listed below in
+.IR futex_op .
+Note that the PI futex operations must be used as paired operations
+and are subject to some additional requirements:
+.IP \[bu] 3
+.BR FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+and
+.B FUTEX_TRYLOCK_PI
+pair with
+.BR FUTEX_UNLOCK_PI .
+.B FUTEX_UNLOCK_PI
+must be called only on a futex owned by the calling thread,
+as defined by the value policy, otherwise the error
+.B EPERM
+results.
+.IP \[bu]
+.B FUTEX_WAIT_REQUEUE_PI
+pairs with
+.BR FUTEX_CMP_REQUEUE_PI .
+This must be performed from a non-PI futex to a distinct PI futex
+(or the error
+.B EINVAL
+results).
+Additionally,
+.I val
+(the number of waiters to be woken) must be 1
+(or the error
+.B EINVAL
+results).
+.P
+The PI futex operations are as follows:
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_LOCK_PI " (since Linux 2.6.18)"
+.\" commit c87e2837be82df479a6bae9f155c43516d2feebc
+This operation is used after an attempt to acquire
+the lock via an atomic user-mode instruction failed
+because the futex word has a nonzero value\[em]specifically,
+because it contained the (PID-namespace-specific) TID of the lock owner.
+.IP
+The operation checks the value of the futex word at the address
+.IR uaddr .
+If the value is 0, then the kernel tries to atomically set
+the futex value to the caller's TID.
+If the futex word's value is nonzero,
+the kernel atomically sets the
+.B FUTEX_WAITERS
+bit, which signals the futex owner that it cannot unlock the futex in
+user space atomically by setting the futex value to 0.
+.\" tglx (July 2015):
+.\"     The operation here is similar to the FUTEX_WAIT logic. When the user
+.\"     space atomic acquire does not succeed because the futex value was non
+.\"     zero, then the waiter goes into the kernel, takes the kernel internal
+.\"     lock and retries the acquisition under the lock. If the acquisition
+.\"     does not succeed either, then it sets the FUTEX_WAITERS bit, to signal
+.\"     the lock owner that it needs to go into the kernel. Here is the pseudo
+.\"     code:
+.\"
+.\"     	lock(kernel_lock);
+.\"     retry:
+.\"
+.\"     	/*
+.\"     	 * Owner might have unlocked in user space before we
+.\"     	 * were able to set the waiter bit.
+.\"              */
+.\"             if (atomic_acquire(futex) == SUCCESS) {
+.\"     	   unlock(kernel_lock());
+.\"     	   return 0;
+.\"     	}
+.\"
+.\"     	/*
+.\"     	 * Owner might have unlocked after the above atomic_acquire()
+.\"     	 * attempt.
+.\"     	 */
+.\"     	if (atomic_set_waiters_bit(futex) != SUCCESS)
+.\"     	   goto retry;
+.\"
+.\"     	queue_waiter();
+.\"     	unlock(kernel_lock);
+.\"     	block();
+.\"
+After that, the kernel:
+.RS
+.IP (1) 5
+Tries to find the thread which is associated with the owner TID.
+.IP (2)
+Creates or reuses kernel state on behalf of the owner.
+(If this is the first waiter, there is no kernel state for this
+futex, so kernel state is created by locking the RT-mutex
+and the futex owner is made the owner of the RT-mutex.
+If there are existing waiters, then the existing state is reused.)
+.IP (3)
+Attaches the waiter to the futex
+(i.e., the waiter is enqueued on the RT-mutex waiter list).
+.RE
+.IP
+If more than one waiter exists,
+the enqueueing of the waiter is in descending priority order.
+(For information on priority ordering, see the discussion of the
+.BR SCHED_DEADLINE ,
+.BR SCHED_FIFO ,
+and
+.B SCHED_RR
+scheduling policies in
+.BR sched (7).)
+The owner inherits either the waiter's CPU bandwidth
+(if the waiter is scheduled under the
+.B SCHED_DEADLINE
+policy) or the waiter's priority (if the waiter is scheduled under the
+.B SCHED_RR
+or
+.B SCHED_FIFO
+policy).
+.\" August 2015:
+.\"     mtk: If the realm is restricted purely to SCHED_OTHER (SCHED_NORMAL)
+.\"          processes, does the nice value come into play also?
+.\"
+.\"     tglx: No. SCHED_OTHER/NORMAL tasks are handled in FIFO order
+This inheritance follows the lock chain in the case of nested locking
+.\" (i.e., task 1 blocks on lock A, held by task 2,
+.\" while task 2 blocks on lock B, held by task 3)
+and performs deadlock detection.
+.IP
+The
+.I timeout
+argument provides a timeout for the lock attempt.
+If
+.I timeout
+is not NULL, the structure it points to specifies
+an absolute timeout, measured against the
+.B CLOCK_REALTIME
+clock.
+.\" 2016-07-07 response from Thomas Gleixner on LKML:
+.\" From: Thomas Gleixner <tglx@linutronix.de>
+.\" Date: 6 July 2016 at 20:57
+.\" Subject: Re: futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op
+.\"
+.\" On Thu, 23 Jun 2016, Michael Kerrisk (man-pages) wrote:
+.\" > On 06/23/2016 08:28 PM, Darren Hart wrote:
+.\" > > And as a follow-on, what is the reason for FUTEX_LOCK_PI only using
+.\" > > CLOCK_REALTIME? It seems reasonable to me that a user may want to wait a
+.\" > > specific amount of time, regardless of wall time.
+.\" >
+.\" > Yes, that's another weird inconsistency.
+.\"
+.\" The reason is that phtread_mutex_timedlock() uses absolute timeouts based on
+.\" CLOCK_REALTIME. glibc folks asked to make that the default behaviour back
+.\" then when we added LOCK_PI.
+If
+.I timeout
+is NULL, the operation will block indefinitely.
+.IP
+The
+.IR uaddr2 ,
+.IR val ,
+and
+.I val3
+arguments are ignored.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_LOCK_PI2 " (since Linux 5.14)"
+.\" commit bf22a6976897977b0a3f1aeba6823c959fc4fdae
+This operation is the same as
+.BR FUTEX_LOCK_PI ,
+except that the clock against which
+.I timeout
+is measured is selectable.
+By default, the (absolute) timeout specified in
+.I timeout
+is measured against the
+.B CLOCK_MONOTONIC
+clock, but if the
+.B FUTEX_CLOCK_REALTIME
+flag is specified in
+.IR futex_op ,
+then the timeout is measured against the
+.B CLOCK_REALTIME
+clock.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_TRYLOCK_PI " (since Linux 2.6.18)"
+.\" commit c87e2837be82df479a6bae9f155c43516d2feebc
+This operation tries to acquire the lock at
+.IR uaddr .
+It is invoked when a user-space atomic acquire did not
+succeed because the futex word was not 0.
+.IP
+Because the kernel has access to more state information than user space,
+acquisition of the lock might succeed if performed by the
+kernel in cases where the futex word
+(i.e., the state information accessible to use-space) contains stale state
+.RB ( FUTEX_WAITERS
+and/or
+.BR FUTEX_OWNER_DIED ).
+This can happen when the owner of the futex died.
+User space cannot handle this condition in a race-free manner,
+but the kernel can fix this up and acquire the futex.
+.\" Paraphrasing a f2f conversation with Thomas Gleixner about the
+.\" above point (Aug 2015): ###
+.\"	There is a rare possibility of a race condition involving an
+.\"	uncontended futex with no owner, but with waiters.  The
+.\"	kernel-user-space contract is that if a futex is nonzero, you must
+.\"	go into kernel.  The futex was owned by a task, and that task dies
+.\"	but there are no waiters, so the futex value is non zero.
+.\"	Therefore, the next locker has to go into the kernel,
+.\"	so that the kernel has a chance to clean up. (CMXCH on zero
+.\"	in user space would fail, so kernel has to clean up.)
+.\" Darren Hart (Oct 2015):
+.\"     The trylock in the kernel has more state, so it can independently
+.\"     verify the flags that user space must trust implicitly.
+.IP
+The
+.IR uaddr2 ,
+.IR val ,
+.IR timeout ,
+and
+.I val3
+arguments are ignored.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_UNLOCK_PI " (since Linux 2.6.18)"
+.\" commit c87e2837be82df479a6bae9f155c43516d2feebc
+This operation wakes the top priority waiter that is waiting in
+.B FUTEX_LOCK_PI
+or
+.B FUTEX_LOCK_PI2
+on the futex address provided by the
+.I uaddr
+argument.
+.IP
+This is called when the user-space value at
+.I uaddr
+cannot be changed atomically from a TID (of the owner) to 0.
+.IP
+The
+.IR uaddr2 ,
+.IR val ,
+.IR timeout ,
+and
+.I val3
+arguments are ignored.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_CMP_REQUEUE_PI " (since Linux 2.6.31)"
+.\" commit 52400ba946759af28442dee6265c5c0180ac7122
+This operation is a PI-aware variant of
+.BR FUTEX_CMP_REQUEUE .
+It requeues waiters that are blocked via
+.B FUTEX_WAIT_REQUEUE_PI
+on
+.I uaddr
+from a non-PI source futex
+.RI ( uaddr )
+to a PI target futex
+.RI ( uaddr2 ).
+.IP
+As with
+.BR FUTEX_CMP_REQUEUE ,
+this operation wakes up a maximum of
+.I val
+waiters that are waiting on the futex at
+.IR uaddr .
+However, for
+.BR FUTEX_CMP_REQUEUE_PI ,
+.I val
+is required to be 1
+(since the main point is to avoid a thundering herd).
+The remaining waiters are removed from the wait queue of the source futex at
+.I uaddr
+and added to the wait queue of the target futex at
+.IR uaddr2 .
+.IP
+The
+.I val2
+.\" val2 is the cap on the number of requeued waiters.
+.\" In the glibc pthread_cond_broadcast() implementation, this argument
+.\" is specified as INT_MAX, and for pthread_cond_signal() it is 0.
+and
+.I val3
+arguments serve the same purposes as for
+.BR FUTEX_CMP_REQUEUE .
+.\"
+.\"       The page at http://locklessinc.com/articles/futex_cheat_sheet/
+.\"       notes that "priority-inheritance Futex to priority-inheritance
+.\"       Futex requeues are currently unsupported". However, probably
+.\"       the page does not need to say nothing about this, since
+.\"       Thomas Gleixner commented (July 2015): "they never will be
+.\"       supported because they make no sense at all"
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.TP
+.BR FUTEX_WAIT_REQUEUE_PI " (since Linux 2.6.31)"
+.\" commit 52400ba946759af28442dee6265c5c0180ac7122
+.\"
+Wait on a non-PI futex at
+.I uaddr
+and potentially be requeued (via a
+.B FUTEX_CMP_REQUEUE_PI
+operation in another task) onto a PI futex at
+.IR uaddr2 .
+The wait operation on
+.I uaddr
+is the same as for
+.BR FUTEX_WAIT .
+.IP
+The waiter can be removed from the wait on
+.I uaddr
+without requeueing on
+.I uaddr2
+via a
+.B FUTEX_WAKE
+operation in another task.
+In this case, the
+.B FUTEX_WAIT_REQUEUE_PI
+operation fails with the error
+.BR EAGAIN .
+.IP
+If
+.I timeout
+is not NULL, the structure it points to specifies
+an absolute timeout for the wait operation.
+If
+.I timeout
+is NULL, the operation can block indefinitely.
+.IP
+The
+.I val3
+argument is ignored.
+.IP
+The
+.B FUTEX_WAIT_REQUEUE_PI
+and
+.B FUTEX_CMP_REQUEUE_PI
+were added to support a fairly specific use case:
+support for priority-inheritance-aware POSIX threads condition variables.
+The idea is that these operations should always be paired,
+in order to ensure that user space and the kernel remain in sync.
+Thus, in the
+.B FUTEX_WAIT_REQUEUE_PI
+operation, the user-space application pre-specifies the target
+of the requeue that takes place in the
+.B FUTEX_CMP_REQUEUE_PI
+operation.
+.\"
+.\" Darren Hart notes that a patch to allow glibc to fully support
+.\" PI-aware pthreads condition variables has not yet been accepted into
+.\" glibc. The story is complex, and can be found at
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=11588
+.\" Darren notes that in the meantime, the patch is shipped with various
+.\" PREEMPT_RT-enabled Linux systems.
+.\"
+.\" Related to the preceding, Darren proposed that somewhere, man-pages
+.\" should document the following point:
+.\"
+.\"     While the Linux kernel, since Linux 2.6.31, supports requeueing of
+.\"     priority-inheritance (PI) aware mutexes via the
+.\"     FUTEX_WAIT_REQUEUE_PI and FUTEX_CMP_REQUEUE_PI futex operations,
+.\"     the glibc implementation does not yet take full advantage of this.
+.\"     Specifically, the condvar internal data lock remains a non-PI aware
+.\"     mutex, regardless of the type of the pthread_mutex associated with
+.\"     the condvar. This can lead to an unbounded priority inversion on
+.\"     the internal data lock even when associating a PI aware
+.\"     pthread_mutex with a condvar during a pthread_cond*_wait
+.\"     operation. For this reason, it is not recommended to rely on
+.\"     priority inheritance when using pthread condition variables.
+.\"
+.\" The problem is that the obvious location for this text is
+.\" the pthread_cond*wait(3) man page. However, such a man page
+.\" does not currently exist.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SH RETURN VALUE
+In the event of an error (and assuming that
+.BR futex ()
+was invoked via
+.BR syscall (2)),
+all operations return \-1 and set
+.I errno
+to indicate the error.
+.P
+The return value on success depends on the operation,
+as described in the following list:
+.TP
+.B FUTEX_WAIT
+Returns 0 if the caller was woken up.
+Note that a wake-up can also be caused by common futex usage patterns
+in unrelated code that happened to have previously used the futex word's
+memory location (e.g., typical futex-based implementations of
+Pthreads mutexes can cause this under some conditions).
+Therefore, callers should always conservatively assume that a return
+value of 0 can mean a spurious wake-up, and use the futex word's value
+(i.e., the user-space synchronization scheme)
+to decide whether to continue to block or not.
+.TP
+.B FUTEX_WAKE
+Returns the number of waiters that were woken up.
+.TP
+.B FUTEX_FD
+Returns the new file descriptor associated with the futex.
+.TP
+.B FUTEX_REQUEUE
+Returns the number of waiters that were woken up.
+.TP
+.B FUTEX_CMP_REQUEUE
+Returns the total number of waiters that were woken up or
+requeued to the futex for the futex word at
+.IR uaddr2 .
+If this value is greater than
+.IR val ,
+then the difference is the number of waiters requeued to the futex for the
+futex word at
+.IR uaddr2 .
+.TP
+.B FUTEX_WAKE_OP
+Returns the total number of waiters that were woken up.
+This is the sum of the woken waiters on the two futexes for
+the futex words at
+.I uaddr
+and
+.IR uaddr2 .
+.TP
+.B FUTEX_WAIT_BITSET
+Returns 0 if the caller was woken up.
+See
+.B FUTEX_WAIT
+for how to interpret this correctly in practice.
+.TP
+.B FUTEX_WAKE_BITSET
+Returns the number of waiters that were woken up.
+.TP
+.B FUTEX_LOCK_PI
+Returns 0 if the futex was successfully locked.
+.TP
+.B FUTEX_LOCK_PI2
+Returns 0 if the futex was successfully locked.
+.TP
+.B FUTEX_TRYLOCK_PI
+Returns 0 if the futex was successfully locked.
+.TP
+.B FUTEX_UNLOCK_PI
+Returns 0 if the futex was successfully unlocked.
+.TP
+.B FUTEX_CMP_REQUEUE_PI
+Returns the total number of waiters that were woken up or
+requeued to the futex for the futex word at
+.IR uaddr2 .
+If this value is greater than
+.IR val ,
+then difference is the number of waiters requeued to the futex for
+the futex word at
+.IR uaddr2 .
+.TP
+.B FUTEX_WAIT_REQUEUE_PI
+Returns 0 if the caller was successfully requeued to the futex for
+the futex word at
+.IR uaddr2 .
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SH ERRORS
+.TP
+.B EACCES
+No read access to the memory of a futex word.
+.TP
+.B EAGAIN
+.RB ( FUTEX_WAIT ,
+.BR FUTEX_WAIT_BITSET ,
+.BR FUTEX_WAIT_REQUEUE_PI )
+The value pointed to by
+.I uaddr
+was not equal to the expected value
+.I val
+at the time of the call.
+.IP
+.BR Note :
+on Linux, the symbolic names
+.B EAGAIN
+and
+.B EWOULDBLOCK
+(both of which appear in different parts of the kernel futex code)
+have the same value.
+.TP
+.B EAGAIN
+.RB ( FUTEX_CMP_REQUEUE ,
+.BR FUTEX_CMP_REQUEUE_PI )
+The value pointed to by
+.I uaddr
+is not equal to the expected value
+.IR val3 .
+.TP
+.B EAGAIN
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+.BR FUTEX_TRYLOCK_PI ,
+.BR FUTEX_CMP_REQUEUE_PI )
+The futex owner thread ID of
+.I uaddr
+(for
+.BR FUTEX_CMP_REQUEUE_PI :
+.IR uaddr2 )
+is about to exit,
+but has not yet handled the internal state cleanup.
+Try again.
+.TP
+.B EDEADLK
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+.BR FUTEX_TRYLOCK_PI ,
+.BR FUTEX_CMP_REQUEUE_PI )
+The futex word at
+.I uaddr
+is already locked by the caller.
+.TP
+.B EDEADLK
+.\" FIXME . I see that kernel/locking/rtmutex.c uses EDEADLK in some
+.\"       places, and EDEADLOCK in others. On almost all architectures
+.\"       these constants are synonymous. Is there a reason that both
+.\"       names are used?
+.\"
+.\"       tglx (July 2015): "No. We should probably fix that."
+.\"
+.RB ( FUTEX_CMP_REQUEUE_PI )
+While requeueing a waiter to the PI futex for the futex word at
+.IR uaddr2 ,
+the kernel detected a deadlock.
+.TP
+.B EFAULT
+A required pointer argument (i.e.,
+.IR uaddr ,
+.IR uaddr2 ,
+or
+.IR timeout )
+did not point to a valid user-space address.
+.TP
+.B EINTR
+A
+.B FUTEX_WAIT
+or
+.B FUTEX_WAIT_BITSET
+operation was interrupted by a signal (see
+.BR signal (7)).
+Before Linux 2.6.22, this error could also be returned for
+a spurious wakeup; since Linux 2.6.22, this no longer happens.
+.TP
+.B EINVAL
+The operation in
+.I futex_op
+is one of those that employs a timeout, but the supplied
+.I timeout
+argument was invalid
+.RI ( tv_sec
+was less than zero, or
+.I tv_nsec
+was not less than 1,000,000,000).
+.TP
+.B EINVAL
+The operation specified in
+.I futex_op
+employs one or both of the pointers
+.I uaddr
+and
+.IR uaddr2 ,
+but one of these does not point to a valid object\[em]that is,
+the address is not four-byte-aligned.
+.TP
+.B EINVAL
+.RB ( FUTEX_WAIT_BITSET ,
+.BR FUTEX_WAKE_BITSET )
+The bit mask supplied in
+.I val3
+is zero.
+.TP
+.B EINVAL
+.RB ( FUTEX_CMP_REQUEUE_PI )
+.I uaddr
+equals
+.I uaddr2
+(i.e., an attempt was made to requeue to the same futex).
+.TP
+.B EINVAL
+.RB ( FUTEX_FD )
+The signal number supplied in
+.I val
+is invalid.
+.TP
+.B EINVAL
+.RB ( FUTEX_WAKE ,
+.BR FUTEX_WAKE_OP ,
+.BR FUTEX_WAKE_BITSET ,
+.BR FUTEX_REQUEUE ,
+.BR FUTEX_CMP_REQUEUE )
+The kernel detected an inconsistency between the user-space state at
+.I uaddr
+and the kernel state\[em]that is, it detected a waiter which waits in
+.B FUTEX_LOCK_PI
+or
+.B FUTEX_LOCK_PI2
+on
+.IR uaddr .
+.TP
+.B EINVAL
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+.BR FUTEX_TRYLOCK_PI ,
+.BR FUTEX_UNLOCK_PI )
+The kernel detected an inconsistency between the user-space state at
+.I uaddr
+and the kernel state.
+This indicates either state corruption
+or that the kernel found a waiter on
+.I uaddr
+which is waiting via
+.B FUTEX_WAIT
+or
+.BR FUTEX_WAIT_BITSET .
+.TP
+.B EINVAL
+.RB ( FUTEX_CMP_REQUEUE_PI )
+The kernel detected an inconsistency between the user-space state at
+.I uaddr2
+and the kernel state;
+.\" From a conversation with Thomas Gleixner (Aug 2015): ###
+.\"	The kernel sees: I have non PI state for a futex you tried to
+.\"     tell me was PI
+that is, the kernel detected a waiter which waits via
+.B FUTEX_WAIT
+or
+.B FUTEX_WAIT_BITSET
+on
+.IR uaddr2 .
+.TP
+.B EINVAL
+.RB ( FUTEX_CMP_REQUEUE_PI )
+The kernel detected an inconsistency between the user-space state at
+.I uaddr
+and the kernel state;
+that is, the kernel detected a waiter which waits via
+.B FUTEX_WAIT
+or
+.B FUTEX_WAIT_BITSET
+on
+.IR uaddr .
+.TP
+.B EINVAL
+.RB ( FUTEX_CMP_REQUEUE_PI )
+The kernel detected an inconsistency between the user-space state at
+.I uaddr
+and the kernel state;
+that is, the kernel detected a waiter which waits on
+.I uaddr
+via
+.B FUTEX_LOCK_PI
+or
+.B FUTEX_LOCK_PI2
+(instead of
+.BR FUTEX_WAIT_REQUEUE_PI ).
+.TP
+.B EINVAL
+.RB ( FUTEX_CMP_REQUEUE_PI )
+.\" This deals with the case:
+.\"     wait_requeue_pi(A, B);
+.\"     requeue_pi(A, C);
+An attempt was made to requeue a waiter to a futex other than that
+specified by the matching
+.B FUTEX_WAIT_REQUEUE_PI
+call for that waiter.
+.TP
+.B EINVAL
+.RB ( FUTEX_CMP_REQUEUE_PI )
+The
+.I val
+argument is not 1.
+.TP
+.B EINVAL
+Invalid argument.
+.TP
+.B ENFILE
+.RB ( FUTEX_FD )
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+.BR FUTEX_TRYLOCK_PI ,
+.BR FUTEX_CMP_REQUEUE_PI )
+The kernel could not allocate memory to hold state information.
+.TP
+.B ENOSYS
+Invalid operation specified in
+.IR futex_op .
+.TP
+.B ENOSYS
+The
+.B FUTEX_CLOCK_REALTIME
+option was specified in
+.IR futex_op ,
+but the accompanying operation was neither
+.BR FUTEX_WAIT ,
+.BR FUTEX_WAIT_BITSET ,
+.BR FUTEX_WAIT_REQUEUE_PI ,
+nor
+.BR FUTEX_LOCK_PI2 .
+.TP
+.B ENOSYS
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+.BR FUTEX_TRYLOCK_PI ,
+.BR FUTEX_UNLOCK_PI ,
+.BR FUTEX_CMP_REQUEUE_PI ,
+.BR FUTEX_WAIT_REQUEUE_PI )
+A run-time check determined that the operation is not available.
+The PI-futex operations are not implemented on all architectures and
+are not supported on some CPU variants.
+.TP
+.B EPERM
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+.BR FUTEX_TRYLOCK_PI ,
+.BR FUTEX_CMP_REQUEUE_PI )
+The caller is not allowed to attach itself to the futex at
+.I uaddr
+(for
+.BR FUTEX_CMP_REQUEUE_PI :
+the futex at
+.IR uaddr2 ).
+(This may be caused by a state corruption in user space.)
+.TP
+.B EPERM
+.RB ( FUTEX_UNLOCK_PI )
+The caller does not own the lock represented by the futex word.
+.TP
+.B ESRCH
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_LOCK_PI2 ,
+.BR FUTEX_TRYLOCK_PI ,
+.BR FUTEX_CMP_REQUEUE_PI )
+The thread ID in the futex word at
+.I uaddr
+does not exist.
+.TP
+.B ESRCH
+.RB ( FUTEX_CMP_REQUEUE_PI )
+The thread ID in the futex word at
+.I uaddr2
+does not exist.
+.TP
+.B ETIMEDOUT
+The operation in
+.I futex_op
+employed the timeout specified in
+.IR timeout ,
+and the timeout expired before the operation completed.
+.\"
+.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.0.
+.P
+Initial futex support was merged in Linux 2.5.7 but with different
+semantics from what was described above.
+A four-argument system call with the semantics
+described in this page was introduced in Linux 2.5.40.
+A fifth argument was added in Linux 2.5.70,
+and a sixth argument was added in Linux 2.6.7.
+.SH EXAMPLES
+The program below demonstrates use of futexes in a program where a parent
+process and a child process use a pair of futexes located inside a
+shared anonymous mapping to synchronize access to a shared resource:
+the terminal.
+The two processes each write
+.I nloops
+(a command-line argument that defaults to 5 if omitted)
+messages to the terminal and employ a synchronization protocol
+that ensures that they alternate in writing messages.
+Upon running this program we see output such as the following:
+.P
+.in +4n
+.EX
+$ \fB./futex_demo\fP
+Parent (18534) 0
+Child  (18535) 0
+Parent (18534) 1
+Child  (18535) 1
+Parent (18534) 2
+Child  (18535) 2
+Parent (18534) 3
+Child  (18535) 3
+Parent (18534) 4
+Child  (18535) 4
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (futex.c)
+.EX
+/* futex_demo.c
+\&
+   Usage: futex_demo [nloops]
+                    (Default: 5)
+\&
+   Demonstrate the use of futexes in a program where parent and child
+   use a pair of futexes located inside a shared anonymous mapping to
+   synchronize access to a shared resource: the terminal. The two
+   processes each write \[aq]num\-loops\[aq] messages to the terminal and employ
+   a synchronization protocol that ensures that they alternate in
+   writing messages.
+*/
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <linux/futex.h>
+#include <stdatomic.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <unistd.h>
+\&
+static uint32_t *futex1, *futex2, *iaddr;
+\&
+static int
+futex(uint32_t *uaddr, int futex_op, uint32_t val,
+      const struct timespec *timeout, uint32_t *uaddr2, uint32_t val3)
+{
+    return syscall(SYS_futex, uaddr, futex_op, val,
+                   timeout, uaddr2, val3);
+}
+\&
+/* Acquire the futex pointed to by \[aq]futexp\[aq]: wait for its value to
+   become 1, and then set the value to 0. */
+\&
+static void
+fwait(uint32_t *futexp)
+{
+    long            s;
+    const uint32_t  one = 1;
+\&
+    /* atomic_compare_exchange_strong(ptr, oldval, newval)
+       atomically performs the equivalent of:
+\&
+           if (*ptr == *oldval)
+               *ptr = newval;
+\&
+       It returns true if the test yielded true and *ptr was updated. */
+\&
+    while (1) {
+\&
+        /* Is the futex available? */
+        if (atomic_compare_exchange_strong(futexp, &one, 0))
+            break;      /* Yes */
+\&
+        /* Futex is not available; wait. */
+\&
+        s = futex(futexp, FUTEX_WAIT, 0, NULL, NULL, 0);
+        if (s == \-1 && errno != EAGAIN)
+            err(EXIT_FAILURE, "futex\-FUTEX_WAIT");
+    }
+}
+\&
+/* Release the futex pointed to by \[aq]futexp\[aq]: if the futex currently
+   has the value 0, set its value to 1 and then wake any futex waiters,
+   so that if the peer is blocked in fwait(), it can proceed. */
+\&
+static void
+fpost(uint32_t *futexp)
+{
+    long            s;
+    const uint32_t  zero = 0;
+\&
+    /* atomic_compare_exchange_strong() was described
+       in comments above. */
+\&
+    if (atomic_compare_exchange_strong(futexp, &zero, 1)) {
+        s = futex(futexp, FUTEX_WAKE, 1, NULL, NULL, 0);
+        if (s  == \-1)
+            err(EXIT_FAILURE, "futex\-FUTEX_WAKE");
+    }
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    pid_t         childPid;
+    unsigned int  nloops;
+\&
+    setbuf(stdout, NULL);
+\&
+    nloops = (argc > 1) ? atoi(argv[1]) : 5;
+\&
+    /* Create a shared anonymous mapping that will hold the futexes.
+       Since the futexes are being shared between processes, we
+       subsequently use the "shared" futex operations (i.e., not the
+       ones suffixed "_PRIVATE"). */
+\&
+    iaddr = mmap(NULL, sizeof(*iaddr) * 2, PROT_READ | PROT_WRITE,
+                 MAP_ANONYMOUS | MAP_SHARED, \-1, 0);
+    if (iaddr == MAP_FAILED)
+        err(EXIT_FAILURE, "mmap");
+\&
+    futex1 = &iaddr[0];
+    futex2 = &iaddr[1];
+\&
+    *futex1 = 0;        /* State: unavailable */
+    *futex2 = 1;        /* State: available */
+\&
+    /* Create a child process that inherits the shared anonymous
+       mapping. */
+\&
+    childPid = fork();
+    if (childPid == \-1)
+        err(EXIT_FAILURE, "fork");
+\&
+    if (childPid == 0) {        /* Child */
+        for (unsigned int j = 0; j < nloops; j++) {
+            fwait(futex1);
+            printf("Child  (%jd) %u\en", (intmax_t) getpid(), j);
+            fpost(futex2);
+        }
+\&
+        exit(EXIT_SUCCESS);
+    }
+\&
+    /* Parent falls through to here. */
+\&
+    for (unsigned int j = 0; j < nloops; j++) {
+        fwait(futex2);
+        printf("Parent (%jd) %u\en", (intmax_t) getpid(), j);
+        fpost(futex1);
+    }
+\&
+    wait(NULL);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.BR get_robust_list (2),
+.BR restart_syscall (2),
+.BR pthread_mutexattr_getprotocol (3),
+.BR futex (7),
+.BR sched (7)
+.P
+The following kernel source files:
+.IP \[bu] 3
+.I Documentation/pi\-futex.txt
+.IP \[bu]
+.I Documentation/futex\-requeue\-pi.txt
+.IP \[bu]
+.I Documentation/locking/rt\-mutex.txt
+.IP \[bu]
+.I Documentation/locking/rt\-mutex\-design.txt
+.IP \[bu]
+.I Documentation/robust\-futex\-ABI.txt
+.P
+Franke, H., Russell, R., and Kirwood, M., 2002.
+\fIFuss, Futexes and Furwocks: Fast Userlevel Locking in Linux\fP
+(from proceedings of the Ottawa Linux Symposium 2002),
+.br
+.UR http://kernel.org\:/doc\:/ols\:/2002\:/ols2002\-pages\-479\-495.pdf
+.UE
+.P
+Hart, D., 2009. \fIA futex overview and update\fP,
+.UR http://lwn.net/Articles/360699/
+.UE
+.P
+Hart, D.\& and Guniguntala, D., 2009.
+\fIRequeue-PI: Making glibc Condvars PI-Aware\fP
+(from proceedings of the 2009 Real-Time Linux Workshop),
+.UR http://lwn.net/images/conf/rtlws11/papers/proc/p10.pdf
+.UE
+.P
+Drepper, U., 2011. \fIFutexes Are Tricky\fP,
+.UR http://www.akkadia.org/drepper/futex.pdf
+.UE
+.P
+Futex example library, futex\-*.tar.bz2 at
+.br
+.UR https://mirrors.kernel.org\:/pub\:/linux\:/kernel\:/people\:/rusty/
+.UE
+.\"
+.\" FIXME(Torvald) We should probably refer to the glibc code here, in
+.\" particular the glibc-internal futex wrapper functions that are
+.\" WIP, and the generic pthread_mutex_t and perhaps condvar
+.\" implementations.
diff --git a/man/man2/futimesat.2 b/man/man2/futimesat.2
new file mode 100644
index 000000000..78b5431ed
--- /dev/null
+++ b/man/man2/futimesat.2
@@ -0,0 +1,128 @@
+.\" This manpage is Copyright (C) 2006, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH futimesat 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+futimesat \- change timestamps of a file relative to a \
+directory file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" "            /* Definition of " AT_* " constants */"
+.B #include <sys/time.h>
+.P
+.BI "[[deprecated]] int futimesat(int " dirfd ", const char *" pathname ,
+.BI "                             const struct timeval " times [2]);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR futimesat ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+This system call is obsolete.
+Use
+.BR utimensat (2)
+instead.
+.P
+The
+.BR futimesat ()
+system call operates in exactly the same way as
+.BR utimes (2),
+except for the differences described in this manual page.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR utimes (2)
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR utimes (2)).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+(See
+.BR openat (2)
+for an explanation of why the
+.I dirfd
+argument is useful.)
+.SH RETURN VALUE
+On success,
+.BR futimesat ()
+returns a 0.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The same errors that occur for
+.BR utimes (2)
+can also occur for
+.BR futimesat ().
+The following additional errors can occur for
+.BR futimesat ():
+.TP
+.B EBADF
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B ENOTDIR
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH VERSIONS
+.SS glibc
+If
+.I pathname
+is NULL, then the glibc
+.BR futimesat ()
+wrapper function updates the times for the file referred to by
+.IR dirfd .
+.\" The Solaris futimesat() also has this strangeness.
+.SH STANDARDS
+None.
+.SH HISTORY
+Linux 2.6.16,
+glibc 2.4.
+.P
+It was implemented from a specification that was proposed for POSIX.1,
+but that specification was replaced by the one for
+.BR utimensat (2).
+.P
+A similar system call exists on Solaris.
+.SH NOTES
+.SH SEE ALSO
+.BR stat (2),
+.BR utimensat (2),
+.BR utimes (2),
+.BR futimes (3),
+.BR path_resolution (7)
diff --git a/man/man2/get_kernel_syms.2 b/man/man2/get_kernel_syms.2
new file mode 100644
index 000000000..f032705e7
--- /dev/null
+++ b/man/man2/get_kernel_syms.2
@@ -0,0 +1,88 @@
+.\" Copyright (C) 1996 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" 2006-02-09, some reformatting by Luc Van Oostenryck; some
+.\" reformatting and rewordings by mtk
+.\"
+.TH get_kernel_syms 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+get_kernel_syms \- retrieve exported kernel and module symbols
+.SH SYNOPSIS
+.nf
+.B #include <linux/module.h>
+.P
+.BI "[[deprecated]] int get_kernel_syms(struct kernel_sym *" table );
+.fi
+.SH DESCRIPTION
+.BR Note :
+This system call is present only before Linux 2.6.
+.P
+If
+.I table
+is NULL,
+.BR get_kernel_syms ()
+returns the number of symbols available for query.
+Otherwise, it fills in a table of structures:
+.P
+.in +4n
+.EX
+struct kernel_sym {
+    unsigned long value;
+    char          name[60];
+};
+.EE
+.in
+.P
+The symbols are interspersed with magic symbols of the form
+.BI # module-name
+with the kernel having an empty name.
+The value associated with a symbol of this form is the address at
+which the module is loaded.
+.P
+The symbols exported from each module follow their magic module tag
+and the modules are returned in the reverse of the
+order in which they were loaded.
+.SH RETURN VALUE
+On success, returns the number of symbols copied to
+.IR table .
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+There is only one possible error return:
+.TP
+.B ENOSYS
+.BR get_kernel_syms ()
+is not supported in this version of the kernel.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Removed in Linux 2.6.
+.\" Removed in Linux 2.5.48
+.P
+This obsolete system call is not supported by glibc.
+No declaration is provided in glibc headers, but, through a quirk of history,
+glibc versions before glibc 2.23 did export an ABI for this system call.
+Therefore, in order to employ this system call,
+it was sufficient to manually declare the interface in your code;
+alternatively, you could invoke the system call using
+.BR syscall (2).
+.SH BUGS
+There is no way to indicate the size of the buffer allocated for
+.IR table .
+If symbols have been added to the kernel since the
+program queried for the symbol table size, memory will be corrupted.
+.P
+The length of exported symbol names is limited to 59 characters.
+.P
+Because of these limitations, this system call is deprecated in
+favor of
+.BR query_module (2)
+(which is itself nowadays deprecated
+in favor of other interfaces described on its manual page).
+.SH SEE ALSO
+.BR create_module (2),
+.BR delete_module (2),
+.BR init_module (2),
+.BR query_module (2)
diff --git a/man/man2/get_mempolicy.2 b/man/man2/get_mempolicy.2
new file mode 100644
index 000000000..f6f80ab3e
--- /dev/null
+++ b/man/man2/get_mempolicy.2
@@ -0,0 +1,239 @@
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft-var
+.\"
+.\" Copyright 2003,2004 Andi Kleen, SuSE Labs.
+.\" and Copyright 2007 Lee Schermerhorn, Hewlett Packard
+.\"
+.\" 2006-02-03, mtk, substantial wording changes and other improvements
+.\" 2007-08-27, Lee Schermerhorn <Lee.Schermerhorn@hp.com>
+.\"     more precise specification of behavior.
+.\"
+.TH get_mempolicy 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+get_mempolicy \- retrieve NUMA memory policy for a thread
+.SH LIBRARY
+NUMA (Non-Uniform Memory Access) policy library
+.RI ( libnuma ", " \-lnuma )
+.SH SYNOPSIS
+.B "#include <numaif.h>"
+.nf
+.P
+.BI "long get_mempolicy(int *" mode ,
+.BI "                   unsigned long " nodemask [(. maxnode " + ULONG_WIDTH - 1)"
+.B "                                          / ULONG_WIDTH],"
+.BI "                   unsigned long " maxnode ", void *" addr ,
+.BI "                   unsigned long " flags );
+.fi
+.SH DESCRIPTION
+.BR get_mempolicy ()
+retrieves the NUMA policy of the calling thread or of a memory address,
+depending on the setting of
+.IR flags .
+.P
+A NUMA machine has different
+memory controllers with different distances to specific CPUs.
+The memory policy defines from which node memory is allocated for
+the thread.
+.P
+If
+.I flags
+is specified as 0,
+then information about the calling thread's default policy
+(as set by
+.BR set_mempolicy (2))
+is returned, in the buffers pointed to by
+.I mode
+and
+.IR nodemask .
+The value returned in these arguments
+may be used to restore the thread's policy to its state at
+the time of the call to
+.BR get_mempolicy ()
+using
+.BR set_mempolicy (2).
+When
+.I flags
+is 0,
+.I addr
+must be specified as NULL.
+.P
+If
+.I flags
+specifies
+.B MPOL_F_MEMS_ALLOWED
+(available since Linux 2.6.24), the
+.I mode
+argument is ignored and the set of nodes (memories) that the
+thread is allowed to specify in subsequent calls to
+.BR mbind (2)
+or
+.BR set_mempolicy (2)
+(in the absence of any
+.IR "mode flags" )
+is returned in
+.IR nodemask .
+It is not permitted to combine
+.B MPOL_F_MEMS_ALLOWED
+with either
+.B MPOL_F_ADDR
+or
+.BR MPOL_F_NODE .
+.P
+If
+.I flags
+specifies
+.BR MPOL_F_ADDR ,
+then information is returned about the policy governing the memory
+address given in
+.IR addr .
+This policy may be different from the thread's default policy if
+.BR mbind (2)
+or one of the helper functions described in
+.BR numa (3)
+has been used to establish a policy for the memory range containing
+.IR addr .
+.P
+If the
+.I mode
+argument is not NULL, then
+.BR get_mempolicy ()
+will store the policy mode and any optional
+.I "mode flags"
+of the requested NUMA policy in the location pointed to by this argument.
+If
+.I nodemask
+is not NULL, then the nodemask associated with the policy will be stored
+in the location pointed to by this argument.
+.I maxnode
+specifies the number of node IDs
+that can be stored into
+.IR nodemask \[em]that
+is, the maximum node ID plus one.
+The value specified by
+.I maxnode
+is always rounded to a multiple of
+.IR "sizeof(unsigned\ long)*8" .
+.P
+If
+.I flags
+specifies both
+.B MPOL_F_NODE
+and
+.BR MPOL_F_ADDR ,
+.BR get_mempolicy ()
+will return the node ID of the node on which the address
+.I addr
+is allocated into the location pointed to by
+.IR mode .
+If no page has yet been allocated for the specified address,
+.BR get_mempolicy ()
+will allocate a page as if the thread had performed a read
+(load) access to that address, and return the ID of the node
+where that page was allocated.
+.P
+If
+.I flags
+specifies
+.BR MPOL_F_NODE ,
+but not
+.BR MPOL_F_ADDR ,
+and the thread's current policy is
+.B MPOL_INTERLEAVE
+or
+.BR MPOL_WEIGHTED_INTERLEAVE ,
+then
+.BR get_mempolicy ()
+will return in the location pointed to by a non-NULL
+.I mode
+argument,
+the node ID of the next node that will be used for
+interleaving of internal kernel pages allocated on behalf of the thread.
+.\" Note:  code returns next interleave node via 'mode' argument -Lee Schermerhorn
+These allocations include pages for memory-mapped files in
+process memory ranges mapped using the
+.BR mmap (2)
+call with the
+.B MAP_PRIVATE
+flag for read accesses, and in memory ranges mapped with the
+.B MAP_SHARED
+flag for all accesses.
+.P
+Other flag values are reserved.
+.P
+For an overview of the possible policies see
+.BR set_mempolicy (2).
+.SH RETURN VALUE
+On success,
+.BR get_mempolicy ()
+returns 0;
+on error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Part of all of the memory range specified by
+.I nodemask
+and
+.I maxnode
+points outside your accessible address space.
+.TP
+.B EINVAL
+The value specified by
+.I maxnode
+is less than the number of node IDs supported by the system.
+Or
+.I flags
+specified values other than
+.B MPOL_F_NODE
+or
+.BR MPOL_F_ADDR ;
+or
+.I flags
+specified
+.B MPOL_F_ADDR
+and
+.I addr
+is NULL,
+or
+.I flags
+did not specify
+.B MPOL_F_ADDR
+and
+.I addr
+is not NULL.
+Or,
+.I flags
+specified
+.B MPOL_F_NODE
+but not
+.B MPOL_F_ADDR
+and the current thread policy is neither
+.B MPOL_INTERLEAVE
+nor
+.BR MPOL_WEIGHTED_INTERLEAVE .
+Or,
+.I flags
+specified
+.B MPOL_F_MEMS_ALLOWED
+with either
+.B MPOL_F_ADDR
+or
+.BR MPOL_F_NODE .
+(And there are other
+.B EINVAL
+cases.)
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.7.
+.SH NOTES
+For information on library support, see
+.BR numa (7).
+.SH SEE ALSO
+.BR getcpu (2),
+.BR mbind (2),
+.BR mmap (2),
+.BR set_mempolicy (2),
+.BR numa (3),
+.BR numa (7),
+.BR numactl (8)
diff --git a/man/man2/get_robust_list.2 b/man/man2/get_robust_list.2
new file mode 100644
index 000000000..9fc260022
--- /dev/null
+++ b/man/man2/get_robust_list.2
@@ -0,0 +1,156 @@
+.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+.\" Written by Ivana Varekova <varekova@redhat.com>
+.\" and Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" FIXME Something could be added to this page (or exit(2))
+.\" about exit_robust_list processing
+.\"
+.TH get_robust_list 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+get_robust_list, set_robust_list \- get/set list of robust futexes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/futex.h>" \
+"   /* Definition of " "struct robust_list_head" " */"
+.BR "#include <sys/syscall.h>" "   /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(SYS_get_robust_list, int " pid ,
+.BI "             struct robust_list_head **" head_ptr ", size_t *" len_ptr );
+.B long syscall(SYS_set_robust_list,
+.BI "             struct robust_list_head *" head ", size_t " len );
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+These system calls deal with per-thread robust futex lists.
+These lists are managed in user space:
+the kernel knows only about the location of the head of the list.
+A thread can inform the kernel of the location of its robust futex list using
+.BR set_robust_list ().
+The address of a thread's robust futex list can be obtained using
+.BR get_robust_list ().
+.P
+The purpose of the robust futex list is to ensure that if a thread
+accidentally fails to unlock a futex before terminating or calling
+.BR execve (2),
+another thread that is waiting on that futex is notified that
+the former owner of the futex has died.
+This notification consists of two pieces: the
+.B FUTEX_OWNER_DIED
+bit is set in the futex word, and the kernel performs a
+.BR futex (2)
+.B FUTEX_WAKE
+operation on one of the threads waiting on the futex.
+.P
+The
+.BR get_robust_list ()
+system call returns the head of the robust futex list of the thread
+whose thread ID is specified in
+.IR pid .
+If
+.I pid
+is 0,
+the head of the list for the calling thread is returned.
+The list head is stored in the location pointed to by
+.IR head_ptr .
+The size of the object pointed to by
+.I **head_ptr
+is stored in
+.IR len_ptr .
+.P
+Permission to employ
+.BR get_robust_list ()
+is governed by a ptrace access mode
+.B PTRACE_MODE_READ_REALCREDS
+check; see
+.BR ptrace (2).
+.P
+The
+.BR set_robust_list ()
+system call requests the kernel to record the head of the list of
+robust futexes owned by the calling thread.
+The
+.I head
+argument is the list head to record.
+The
+.I len
+argument should be
+.IR sizeof(*head) .
+.SH RETURN VALUE
+The
+.BR set_robust_list ()
+and
+.BR get_robust_list ()
+system calls return zero when the operation is successful,
+an error code otherwise.
+.SH ERRORS
+The
+.BR set_robust_list ()
+system call can fail with the following error:
+.TP
+.B EINVAL
+.I len
+does not equal
+.IR "sizeof(struct\ robust_list_head)" .
+.P
+The
+.BR get_robust_list ()
+system call can fail with the following errors:
+.TP
+.B EFAULT
+The head of the robust futex list can't be stored at the location
+.IR head .
+.TP
+.B EPERM
+The calling process does not have permission to see the robust futex list of
+the thread with the thread ID
+.IR pid ,
+and does not have the
+.B CAP_SYS_PTRACE
+capability.
+.TP
+.B ESRCH
+No thread with the thread ID
+.I pid
+could be found.
+.SH VERSIONS
+These system calls were added in Linux 2.6.17.
+.SH NOTES
+These system calls are not needed by normal applications.
+.P
+A thread can have only one robust futex list;
+therefore applications that wish
+to use this functionality should use the robust mutexes provided by glibc.
+.P
+In the initial implementation,
+a thread waiting on a futex was notified that the owner had died
+only if the owner terminated.
+Starting with Linux 2.6.28,
+.\" commit 8141c7f3e7aee618312fa1c15109e1219de784a7
+notification was extended to include the case where the owner performs an
+.BR execve (2).
+.P
+The thread IDs mentioned in the main text are
+.I kernel
+thread IDs of the kind returned by
+.BR clone (2)
+and
+.BR gettid (2).
+.SH SEE ALSO
+.BR futex (2),
+.BR pthread_mutexattr_setrobust (3)
+.P
+.I Documentation/robust\-futexes.txt
+and
+.I Documentation/robust\-futex\-ABI.txt
+in the Linux kernel source tree
+.\" http://lwn.net/Articles/172149/
diff --git a/man/man2/get_thread_area.2 b/man/man2/get_thread_area.2
new file mode 100644
index 000000000..a03fe54fb
--- /dev/null
+++ b/man/man2/get_thread_area.2
@@ -0,0 +1 @@
+.so man2/set_thread_area.2
diff --git a/man/man2/getcpu.2 b/man/man2/getcpu.2
new file mode 100644
index 000000000..72c500f97
--- /dev/null
+++ b/man/man2/getcpu.2
@@ -0,0 +1,147 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 2006 Andi Kleen <ak@muc.de>.
+.\"
+.\" 2008, mtk, various edits
+.\"
+.TH getcpu 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getcpu \- determine CPU and NUMA node on which the calling thread is running
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sched.h>
+.P
+.BI "int getcpu(unsigned int *_Nullable " cpu ", \
+unsigned int *_Nullable " node );
+.fi
+.SH DESCRIPTION
+The
+.BR getcpu ()
+system call identifies the processor and node on which the calling
+thread or process is currently running and writes them into the
+integers pointed to by the
+.I cpu
+and
+.I node
+arguments.
+The processor is a unique small integer identifying a CPU.
+The node is a unique small identifier identifying a NUMA node.
+When either
+.I cpu
+or
+.I node
+is NULL nothing is written to the respective pointer.
+.P
+The information placed in
+.I cpu
+is guaranteed to be current only at the time of the call:
+unless the CPU affinity has been fixed using
+.BR sched_setaffinity (2),
+the kernel might change the CPU at any time.
+(Normally this does not happen
+because the scheduler tries to minimize movements between CPUs to
+keep caches hot, but it is possible.)
+The caller must allow for the possibility that the information returned in
+.I cpu
+and
+.I node
+is no longer current by the time the call returns.
+.SH RETURN VALUE
+On success, 0 is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Arguments point outside the calling process's address space.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.19 (x86-64 and i386),
+glibc 2.29.
+.\"
+.SS C library/kernel differences
+The kernel system call has a third argument:
+.P
+.in +4n
+.nf
+.BI "int getcpu(unsigned int *" cpu ", unsigned int *" node ,
+.BI "           struct getcpu_cache *" tcache );
+.fi
+.in
+.P
+The
+.I tcache
+argument is unused since Linux 2.6.24,
+and (when invoking the system call directly)
+should be specified as NULL,
+unless portability to Linux 2.6.23 or earlier is required.
+.P
+.\" commit 4307d1e5ada595c87f9a4d16db16ba5edb70dcb1
+.\" Author: Ingo Molnar <mingo@elte.hu>
+.\" Date:   Wed Nov 7 18:37:48 2007 +0100
+.\" x86: ignore the sys_getcpu() tcache parameter
+In Linux 2.6.23 and earlier, if the
+.I tcache
+argument was non-NULL,
+then it specified a pointer to a caller-allocated buffer in thread-local
+storage that was used to provide a caching mechanism for
+.BR getcpu ().
+Use of the cache could speed
+.BR getcpu ()
+calls, at the cost that there was a very small chance that
+the returned information would be out of date.
+The caching mechanism was considered to cause problems when
+migrating threads between CPUs, and so the argument is now ignored.
+.\"
+.\" ===== Before Linux 2.6.24: =====
+.\" .I tcache
+.\" is a pointer to a
+.\" .IR "struct getcpu_cache"
+.\" that is used as a cache by
+.\" .BR getcpu ().
+.\" The caller should put the cache into a thread-local variable
+.\" if the process is multithreaded,
+.\" because the cache cannot be shared between different threads.
+.\" .I tcache
+.\" can be NULL.
+.\" If it is not NULL
+.\" .BR getcpu ()
+.\" will use it to speed up operation.
+.\" The information inside the cache is private to the system call
+.\" and should not be accessed by the user program.
+.\" The information placed in the cache can change between Linux releases.
+.\"
+.\" When no cache is specified
+.\" .BR getcpu ()
+.\" will be slower,
+.\" but always retrieve the current CPU and node information.
+.\" With a cache
+.\" .BR getcpu ()
+.\" is faster.
+.\" However, the cached information is updated only once per jiffy (see
+.\" .BR time (7)).
+.\" This means that the information could theoretically be out of date,
+.\" although in practice the scheduler's attempt to maintain
+.\" soft CPU affinity means that the information is unlikely to change
+.\" over the course of the caching interval.
+.SH NOTES
+Linux makes a best effort to make this call as fast as possible.
+(On some architectures, this is done via an implementation in the
+.BR vdso (7).)
+The intention of
+.BR getcpu ()
+is to allow programs to make optimizations with per-CPU data
+or for NUMA optimization.
+.SH SEE ALSO
+.BR mbind (2),
+.BR sched_setaffinity (2),
+.BR set_mempolicy (2),
+.BR sched_getcpu (3),
+.BR cpuset (7),
+.BR vdso (7)
diff --git a/man/man2/getcwd.2 b/man/man2/getcwd.2
new file mode 100644
index 000000000..f080be0fc
--- /dev/null
+++ b/man/man2/getcwd.2
@@ -0,0 +1,2 @@
+.so man3/getcwd.3
+.\" Because getcwd(3) is layered on a system call of the same name
diff --git a/man/man2/getdents.2 b/man/man2/getdents.2
new file mode 100644
index 000000000..1e630f9e2
--- /dev/null
+++ b/man/man2/getdents.2
@@ -0,0 +1,323 @@
+.\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright 2008, 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Written 11 June 1995 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 22 July 1995 by Michael Chastain <mec@duracef.shout.net>:
+.\"   Derived from 'readdir.2'.
+.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\"
+.TH getdents 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getdents, getdents64 \- get directory entries
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(SYS_getdents, unsigned int " fd \
+", struct linux_dirent *" dirp ,
+.BI "             unsigned int " count );
+.P
+.BR "#define _GNU_SOURCE" "           /* See feature_test_macros(7) */"
+.B #include <dirent.h>
+.P
+.BI "ssize_t getdents64(int " fd ", void " dirp [. count "], size_t " count );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR getdents (),
+necessitating the use of
+.BR syscall (2).
+.P
+.IR Note :
+There is no definition of
+.I struct linux_dirent
+in glibc; see NOTES.
+.SH DESCRIPTION
+These are not the interfaces you are interested in.
+Look at
+.BR readdir (3)
+for the POSIX-conforming C library interface.
+This page documents the bare kernel system call interfaces.
+.SS getdents()
+The system call
+.BR getdents ()
+reads several
+.I linux_dirent
+structures from the directory
+referred to by the open file descriptor
+.I fd
+into the buffer pointed to by
+.IR dirp .
+The argument
+.I count
+specifies the size of that buffer.
+.P
+The
+.I linux_dirent
+structure is declared as follows:
+.P
+.in +4n
+.EX
+struct linux_dirent {
+    unsigned long  d_ino;     /* Inode number */
+    unsigned long  d_off;     /* Not an offset; see below */
+    unsigned short d_reclen;  /* Length of this \fIlinux_dirent\fP */
+    char           d_name[];  /* Filename (null\-terminated) */
+                      /* length is actually (d_reclen \- 2 \-
+                         offsetof(struct linux_dirent, d_name)) */
+    /*
+    char           pad;       // Zero padding byte
+    char           d_type;    // File type (only since Linux
+                              // 2.6.4); offset is (d_reclen \- 1)
+    */
+}
+.EE
+.in
+.P
+.I d_ino
+is an inode number.
+.I d_off
+is a filesystem-specific value with no specific meaning to user space,
+though on older filesystems it used to be
+the distance from the start of the directory to the start of the next
+.IR linux_dirent ;
+see
+.BR readdir (3) .
+.I d_reclen
+is the size of this entire
+.IR linux_dirent .
+.I d_name
+is a null-terminated filename.
+.P
+.I d_type
+is a byte at the end of the structure that indicates the file type.
+It contains one of the following values (defined in
+.IR <dirent.h> ):
+.TP 12
+.B DT_BLK
+This is a block device.
+.TP
+.B DT_CHR
+This is a character device.
+.TP
+.B DT_DIR
+This is a directory.
+.TP
+.B DT_FIFO
+This is a named pipe (FIFO).
+.TP
+.B DT_LNK
+This is a symbolic link.
+.TP
+.B DT_REG
+This is a regular file.
+.TP
+.B DT_SOCK
+This is a UNIX domain socket.
+.TP
+.B DT_UNKNOWN
+The file type is unknown.
+.P
+The
+.I d_type
+field is implemented since Linux 2.6.4.
+It occupies a space that was previously a zero-filled padding byte in the
+.I linux_dirent
+structure.
+Thus, on kernels up to and including Linux 2.6.3,
+attempting to access this field always provides the value 0
+.RB ( DT_UNKNOWN ).
+.P
+Currently,
+.\" kernel 2.6.27
+.\" The same sentence is in readdir.2
+only some filesystems (among them: Btrfs, ext2, ext3, and ext4)
+have full support for returning the file type in
+.IR d_type .
+All applications must properly handle a return of
+.BR DT_UNKNOWN .
+.SS getdents64()
+The original Linux
+.BR getdents ()
+system call did not handle large filesystems and large file offsets.
+Consequently, Linux 2.4 added
+.BR getdents64 (),
+with wider types for the
+.I d_ino
+and
+.I d_off
+fields.
+In addition,
+.BR getdents64 ()
+supports an explicit
+.I d_type
+field.
+.P
+The
+.BR getdents64 ()
+system call is like
+.BR getdents (),
+except that its second argument is a pointer to a buffer containing
+structures of the following type:
+.P
+.in +4n
+.EX
+struct linux_dirent64 {
+    ino64_t        d_ino;    /* 64\-bit inode number */
+    off64_t        d_off;    /* Not an offset; see getdents() */
+    unsigned short d_reclen; /* Size of this dirent */
+    unsigned char  d_type;   /* File type */
+    char           d_name[]; /* Filename (null\-terminated) */
+};
+.EE
+.in
+.SH RETURN VALUE
+On success, the number of bytes read is returned.
+On end of directory, 0 is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+Invalid file descriptor
+.IR fd .
+.TP
+.B EFAULT
+Argument points outside the calling process's address space.
+.TP
+.B EINVAL
+Result buffer is too small.
+.TP
+.B ENOENT
+No such directory.
+.TP
+.B ENOTDIR
+File descriptor does not refer to a directory.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4.
+.\" SVr4 documents additional ENOLINK, EIO error conditions.
+.TP
+.BR getdents64 ()
+glibc 2.30.
+.SH NOTES
+glibc does not provide a wrapper for
+.BR getdents ();
+call
+.BR getdents ()
+using
+.BR syscall (2).
+In that case you will need to define the
+.I linux_dirent
+or
+.I linux_dirent64
+structure yourself.
+.P
+Probably, you want to use
+.BR readdir (3)
+instead of these system calls.
+.P
+These calls supersede
+.BR readdir (2).
+.SH EXAMPLES
+.\" FIXME The example program needs to be revised, since it uses the older
+.\" getdents() system call and the structure with smaller field widths.
+The program below demonstrates the use of
+.BR getdents ().
+The following output shows an example of what we see when running this
+program on an ext2 directory:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out /testfs/"
+-\-\-\-\-\-\-\-\-\-\-\-\-\-\- nread=120 \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
+inode#    file type  d_reclen  d_off   d_name
+       2  directory    16         12  .
+       2  directory    16         24  ..
+      11  directory    24         44  lost+found
+      12  regular      16         56  a
+  228929  directory    16         68  sub
+   16353  directory    16         80  sub2
+  130817  directory    16       4096  sub3
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (getdents.c)
+.EX
+#define _GNU_SOURCE
+#include <dirent.h>     /* Defines DT_* constants */
+#include <err.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+struct linux_dirent {
+    unsigned long  d_ino;
+    off_t          d_off;
+    unsigned short d_reclen;
+    char           d_name[];
+};
+\&
+#define BUF_SIZE 1024
+\&
+int
+main(int argc, char *argv[])
+{
+    int                  fd;
+    char                 d_type;
+    char                 buf[BUF_SIZE];
+    long                 nread;
+    struct linux_dirent  *d;
+\&
+    fd = open(argc > 1 ? argv[1] : ".", O_RDONLY | O_DIRECTORY);
+    if (fd == \-1)
+        err(EXIT_FAILURE, "open");
+\&
+    for (;;) {
+        nread = syscall(SYS_getdents, fd, buf, BUF_SIZE);
+        if (nread == \-1)
+            err(EXIT_FAILURE, "getdents");
+\&
+        if (nread == 0)
+            break;
+\&
+        printf("\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- nread=%ld \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\en", nread);
+        printf("inode#    file type  d_reclen  d_off   d_name\en");
+        for (size_t bpos = 0; bpos < nread;) {
+            d = (struct linux_dirent *) (buf + bpos);
+            printf("%8lu  ", d\->d_ino);
+            d_type = *(buf + bpos + d\->d_reclen \- 1);
+            printf("%\-10s ", (d_type == DT_REG) ?  "regular" :
+                             (d_type == DT_DIR) ?  "directory" :
+                             (d_type == DT_FIFO) ? "FIFO" :
+                             (d_type == DT_SOCK) ? "socket" :
+                             (d_type == DT_LNK) ?  "symlink" :
+                             (d_type == DT_BLK) ?  "block dev" :
+                             (d_type == DT_CHR) ?  "char dev" : "???");
+            printf("%4d %10jd  %s\en", d\->d_reclen,
+                   (intmax_t) d\->d_off, d\->d_name);
+            bpos += d\->d_reclen;
+        }
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR readdir (2),
+.BR readdir (3),
+.BR inode (7)
diff --git a/man/man2/getdents64.2 b/man/man2/getdents64.2
new file mode 100644
index 000000000..f3674bac6
--- /dev/null
+++ b/man/man2/getdents64.2
@@ -0,0 +1 @@
+.so man2/getdents.2
diff --git a/man/man2/getdomainname.2 b/man/man2/getdomainname.2
new file mode 100644
index 000000000..3b74bcd7a
--- /dev/null
+++ b/man/man2/getdomainname.2
@@ -0,0 +1,122 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1997-08-25 by Nicolás Lichtmaier <nick@debian.org>
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2008-11-27 by mtk
+.\"
+.TH getdomainname 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getdomainname, setdomainname \- get/set NIS domain name
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int getdomainname(char *" name ", size_t " len );
+.BI "int setdomainname(const char *" name ", size_t " len );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getdomainname (),
+.BR setdomainname ():
+.nf
+    Since glibc 2.21:
+.\"		commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+These functions are used to access or to change the NIS domain name of the
+host system.
+More precisely, they operate on the NIS domain name associated with the calling
+process's UTS namespace.
+.P
+.BR setdomainname ()
+sets the domain name to the value given in the character array
+.IR name .
+The
+.I len
+argument specifies the number of bytes in
+.IR name .
+(Thus,
+.I name
+does not require a terminating null byte.)
+.P
+.BR getdomainname ()
+returns the null-terminated domain name in the character array
+.IR name ,
+which has a length of
+.I len
+bytes.
+If the null-terminated domain name requires more than \fIlen\fP bytes,
+.BR getdomainname ()
+returns the first \fIlen\fP bytes (glibc) or gives an error (libc).
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR setdomainname ()
+can fail with the following errors:
+.TP
+.B EFAULT
+.I name
+pointed outside of user address space.
+.TP
+.B EINVAL
+.I len
+was negative or too large.
+.TP
+.B EPERM
+The caller did not have the
+.B CAP_SYS_ADMIN
+capability in the user namespace associated with its UTS namespace (see
+.BR namespaces (7)).
+.P
+.BR getdomainname ()
+can fail with the following errors:
+.TP
+.B EINVAL
+For
+.BR getdomainname ()
+under libc:
+.I name
+is NULL or
+.I name
+is longer than
+.I len
+bytes.
+.SH VERSIONS
+On most Linux architectures (including x86),
+there is no
+.BR getdomainname ()
+system call; instead, glibc implements
+.BR getdomainname ()
+as a library function that returns a copy of the
+.I domainname
+field returned from a call to
+.BR uname (2).
+.SH STANDARDS
+None.
+.\" But they appear on most systems...
+.SH HISTORY
+Since Linux 1.0, the limit on the length of a domain name,
+including the terminating null byte, is 64 bytes.
+In older kernels, it was 8 bytes.
+.SH SEE ALSO
+.BR gethostname (2),
+.BR sethostname (2),
+.BR uname (2),
+.BR uts_namespaces (7)
diff --git a/man/man2/getegid.2 b/man/man2/getegid.2
new file mode 100644
index 000000000..d9b10e73f
--- /dev/null
+++ b/man/man2/getegid.2
@@ -0,0 +1 @@
+.so man2/getgid.2
diff --git a/man/man2/getegid32.2 b/man/man2/getegid32.2
new file mode 100644
index 000000000..d7da70863
--- /dev/null
+++ b/man/man2/getegid32.2
@@ -0,0 +1 @@
+.so man2/getegid.2
diff --git a/man/man2/geteuid.2 b/man/man2/geteuid.2
new file mode 100644
index 000000000..165cfe1d0
--- /dev/null
+++ b/man/man2/geteuid.2
@@ -0,0 +1 @@
+.so man2/getuid.2
diff --git a/man/man2/geteuid32.2 b/man/man2/geteuid32.2
new file mode 100644
index 000000000..8e60b7798
--- /dev/null
+++ b/man/man2/geteuid32.2
@@ -0,0 +1 @@
+.so man2/geteuid.2
diff --git a/man/man2/getgid.2 b/man/man2/getgid.2
new file mode 100644
index 000000000..a02515509
--- /dev/null
+++ b/man/man2/getgid.2
@@ -0,0 +1,70 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getgid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getgid, getegid \- get group identity
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B gid_t getgid(void);
+.B gid_t getegid(void);
+.fi
+.SH DESCRIPTION
+.BR getgid ()
+returns the real group ID of the calling process.
+.P
+.BR getegid ()
+returns the effective group ID of the calling process.
+.SH ERRORS
+These functions are always successful
+and never modify
+.\" https://www.austingroupbugs.net/view.php?id=511
+.\" 0000511: getuid and friends should not modify errno
+.IR errno .
+.SH VERSIONS
+On Alpha, instead of a pair of
+.BR getgid ()
+and
+.BR getegid ()
+system calls, a single
+.BR getxgid ()
+system call is provided, which returns a pair of real and effective GIDs.
+The glibc
+.BR getgid ()
+and
+.BR getegid ()
+wrapper functions transparently deal with this.
+See
+.BR syscall (2)
+for details regarding register mapping.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.P
+The original Linux
+.BR getgid ()
+and
+.BR getegid ()
+system calls supported only 16-bit group IDs.
+Subsequently, Linux 2.4 added
+.BR getgid32 ()
+and
+.BR getegid32 (),
+supporting 32-bit IDs.
+The glibc
+.BR getgid ()
+and
+.BR getegid ()
+wrapper functions transparently deal with the variations across kernel versions.
+.SH SEE ALSO
+.BR getresgid (2),
+.BR setgid (2),
+.BR setregid (2),
+.BR credentials (7)
diff --git a/man/man2/getgid32.2 b/man/man2/getgid32.2
new file mode 100644
index 000000000..d9b10e73f
--- /dev/null
+++ b/man/man2/getgid32.2
@@ -0,0 +1 @@
+.so man2/getgid.2
diff --git a/man/man2/getgroups.2 b/man/man2/getgroups.2
new file mode 100644
index 000000000..3d9be4b98
--- /dev/null
+++ b/man/man2/getgroups.2
@@ -0,0 +1,219 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\" and Copyright (C) 2008, 2010, 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Thu Oct 31 12:04:29 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" 2008-05-03, mtk, expanded and rewrote parts of DESCRIPTION and RETURN
+.\"     VALUE, made style of page more consistent with man-pages style.
+.\"
+.TH getgroups 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getgroups, setgroups \- get/set list of supplementary group IDs
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int getgroups(int " size ", gid_t " list []);
+.P
+.B #include <grp.h>
+.P
+.BI "int setgroups(size_t " size ", const gid_t *_Nullable " list );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR setgroups ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR getgroups ()
+returns the supplementary group IDs of the calling process in
+.IR list .
+The argument
+.I size
+should be set to the maximum number of items that can be stored in the
+buffer pointed to by
+.IR list .
+If the calling process is a member of more than
+.I size
+supplementary groups, then an error results.
+.P
+It is unspecified whether the effective group ID of the calling process
+is included in the returned list.
+(Thus, an application should also call
+.BR getegid (2)
+and add or remove the resulting value.)
+.P
+If
+.I size
+is zero,
+.I list
+is not modified, but the total number of supplementary group IDs for the
+process is returned.
+This allows the caller to determine the size of a dynamically allocated
+.I list
+to be used in a further call to
+.BR getgroups ().
+.P
+.BR setgroups ()
+sets the supplementary group IDs for the calling process.
+Appropriate privileges are required (see the description of the
+.B EPERM
+error, below).
+The
+.I size
+argument specifies the number of supplementary group IDs
+in the buffer pointed to by
+.IR list .
+A process can drop all of its supplementary groups with the call:
+.P
+.in +4n
+.EX
+setgroups(0, NULL);
+.EE
+.in
+.SH RETURN VALUE
+On success,
+.BR getgroups ()
+returns the number of supplementary group IDs.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+On success,
+.BR setgroups ()
+returns 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I list
+has an invalid address.
+.P
+.BR getgroups ()
+can additionally fail with the following error:
+.TP
+.B EINVAL
+.I size
+is less than the number of supplementary group IDs, but is not zero.
+.P
+.BR setgroups ()
+can additionally fail with the following errors:
+.TP
+.B EINVAL
+.I size
+is greater than
+.B NGROUPS_MAX
+(32 before Linux 2.6.4; 65536 since Linux 2.6.4).
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B EPERM
+The calling process has insufficient privilege
+(the caller does not have the
+.B CAP_SETGID
+capability in the user namespace in which it resides).
+.TP
+.BR EPERM " (since Linux 3.19)"
+The use of
+.BR setgroups ()
+is denied in this user namespace.
+See the description of
+.IR /proc/ pid /setgroups
+in
+.BR user_namespaces (7).
+.SH VERSIONS
+.SS C library/kernel differences
+At the kernel level, user IDs and group IDs are a per-thread attribute.
+However, POSIX requires that all threads in a process
+share the same credentials.
+The NPTL threading implementation handles the POSIX requirements by
+providing wrapper functions for
+the various system calls that change process UIDs and GIDs.
+These wrapper functions (including the one for
+.BR setgroups ())
+employ a signal-based technique to ensure
+that when one thread changes credentials,
+all of the other threads in the process also change their credentials.
+For details, see
+.BR nptl (7).
+.SH STANDARDS
+.TP
+.BR getgroups ()
+POSIX.1-2008.
+.TP
+.BR setgroups ()
+None.
+.SH HISTORY
+.TP
+.BR getgroups ()
+SVr4, 4.3BSD, POSIX.1-2001.
+.TP
+.BR setgroups ()
+SVr4, 4.3BSD.
+Since
+.BR setgroups ()
+requires privilege, it is not covered by POSIX.1.
+.P
+The original Linux
+.BR getgroups ()
+system call supported only 16-bit group IDs.
+Subsequently, Linux 2.4 added
+.BR getgroups32 (),
+supporting 32-bit IDs.
+The glibc
+.BR getgroups ()
+wrapper function transparently deals with the variation across kernel versions.
+.SH NOTES
+A process can have up to
+.B NGROUPS_MAX
+supplementary group IDs
+in addition to the effective group ID.
+The constant
+.B NGROUPS_MAX
+is defined in
+.IR <limits.h> .
+The set of supplementary group IDs
+is inherited from the parent process, and preserved across an
+.BR execve (2).
+.P
+The maximum number of supplementary group IDs can be found at run time using
+.BR sysconf (3):
+.P
+.in +4n
+.EX
+long ngroups_max;
+ngroups_max = sysconf(_SC_NGROUPS_MAX);
+.EE
+.in
+.P
+The maximum return value of
+.BR getgroups ()
+cannot be larger than one more than this value.
+Since Linux 2.6.4, the maximum number of supplementary group IDs is also
+exposed via the Linux-specific read-only file,
+.IR /proc/sys/kernel/ngroups_max .
+.SH SEE ALSO
+.BR getgid (2),
+.BR setgid (2),
+.BR getgrouplist (3),
+.BR group_member (3),
+.BR initgroups (3),
+.BR capabilities (7),
+.BR credentials (7)
diff --git a/man/man2/getgroups32.2 b/man/man2/getgroups32.2
new file mode 100644
index 000000000..0ae4cc0b1
--- /dev/null
+++ b/man/man2/getgroups32.2
@@ -0,0 +1 @@
+.so man2/getgroups.2
diff --git a/man/man2/gethostname.2 b/man/man2/gethostname.2
new file mode 100644
index 000000000..1a9fc0d2f
--- /dev/null
+++ b/man/man2/gethostname.2
@@ -0,0 +1,176 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1995-07-22 by Michael Chastain <mec@duracef.shout.net>:
+.\"   'gethostname' is real system call on Linux/Alpha.
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2000-06-04, 2001-12-15 by aeb
+.\" Modified 2004-06-17 by mtk
+.\" Modified 2008-11-27 by mtk
+.\"
+.TH gethostname 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gethostname, sethostname \- get/set hostname
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int gethostname(char *" name ", size_t " len );
+.BI "int sethostname(const char *" name ", size_t " len );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR gethostname ():
+.nf
+    _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L
+        || /* glibc 2.19 and earlier */ _BSD_SOURCE
+.\" The above is something of a simplification
+.\" also before glibc 2.3 there was a bit churn
+.fi
+.P
+.BR sethostname ():
+.nf
+    Since glibc 2.21:
+.\"		commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+These system calls are used to access or to change the system hostname.
+More precisely, they operate on the hostname associated with the calling
+process's UTS namespace.
+.P
+.BR sethostname ()
+sets the hostname to the value given in the character array
+.IR name .
+The
+.I len
+argument specifies the number of bytes in
+.IR name .
+(Thus,
+.I name
+does not require a terminating null byte.)
+.P
+.BR gethostname ()
+returns the null-terminated hostname in the character array
+.IR name ,
+which has a length of
+.I len
+bytes.
+If the null-terminated hostname is too large to fit,
+then the name is truncated, and no error is returned (but see NOTES below).
+POSIX.1 says that if such truncation occurs,
+then it is unspecified whether the returned buffer
+includes a terminating null byte.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I name
+is an invalid address.
+.TP
+.B EINVAL
+.I len
+is negative
+.\" Can't occur for gethostbyname() wrapper, since 'len' has an
+.\" unsigned type; can occur for the underlying system call.
+or, for
+.BR sethostname (),
+.I len
+is larger than the maximum allowed size.
+.TP
+.B ENAMETOOLONG
+.RB "(glibc " gethostname ())
+.I len
+is smaller than the actual size.
+(Before glibc 2.1, glibc uses
+.B EINVAL
+for this case.)
+.TP
+.B EPERM
+For
+.BR sethostname (),
+the caller did not have the
+.B CAP_SYS_ADMIN
+capability in the user namespace associated with its UTS namespace (see
+.BR namespaces (7)).
+.SH VERSIONS
+SUSv2 guarantees that "Host names are limited to 255 bytes".
+POSIX.1 guarantees that "Host names (not including
+the terminating null byte) are limited to
+.B HOST_NAME_MAX
+bytes".
+On Linux,
+.B HOST_NAME_MAX
+is defined with the value 64, which has been the limit since Linux 1.0
+(earlier kernels imposed a limit of 8 bytes).
+.SS C library/kernel differences
+The GNU C library does not employ the
+.BR gethostname ()
+system call; instead, it implements
+.BR gethostname ()
+as a library function that calls
+.BR uname (2)
+and copies up to
+.I len
+bytes from the returned
+.I nodename
+field into
+.IR name .
+Having performed the copy, the function then checks if the length of the
+.I nodename
+was greater than or equal to
+.IR len ,
+and if it is, then the function returns \-1 with
+.I errno
+set to
+.BR ENAMETOOLONG ;
+in this case, a terminating null byte is not included in the returned
+.IR name .
+.SH STANDARDS
+.TP
+.BR gethostname ()
+POSIX.1-2008.
+.TP
+.BR sethostname ()
+None.
+.SH HISTORY
+SVr4, 4.4BSD (these interfaces first appeared in 4.2BSD).
+POSIX.1-2001 and POSIX.1-2008 specify
+.BR gethostname ()
+but not
+.BR sethostname ().
+.P
+Versions of glibc before glibc 2.2
+.\" At least glibc 2.0 and glibc 2.1, older versions not checked
+handle the case where the length of the
+.I nodename
+was greater than or equal to
+.I len
+differently: nothing is copied into
+.I name
+and the function returns \-1 with
+.I errno
+set to
+.BR ENAMETOOLONG .
+.SH SEE ALSO
+.BR hostname (1),
+.BR getdomainname (2),
+.BR setdomainname (2),
+.BR uname (2),
+.BR uts_namespaces (7)
diff --git a/man/man2/getitimer.2 b/man/man2/getitimer.2
new file mode 100644
index 000000000..b0a97c68f
--- /dev/null
+++ b/man/man2/getitimer.2
@@ -0,0 +1,278 @@
+.\" Copyright 7/93 by Darren Senn <sinster@scintilla.santa-clara.ca.us>
+.\" and Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Based on a similar page Copyright 1992 by Rick Faith
+.\"
+.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE)
+.\" May be freely distributed and modified
+.\" %%%LICENSE_END
+.\"
+.\" Modified Tue Oct 22 00:22:35 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" 2005-04-06 mtk, Matthias Lang <matthias@corelatus.se>
+.\" 	Noted MAX_SEC_IN_JIFFIES ceiling
+.\"
+.TH getitimer 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getitimer, setitimer \- get or set value of an interval timer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/time.h>
+.P
+.BI "int getitimer(int " which ", struct itimerval *" curr_value );
+.BI "int setitimer(int " which ", const struct itimerval *restrict " new_value ,
+.BI "              struct itimerval *_Nullable restrict " old_value );
+.fi
+.SH DESCRIPTION
+These system calls provide access to interval timers, that is,
+timers that initially expire at some point in the future,
+and (optionally) at regular intervals after that.
+When a timer expires, a signal is generated for the calling process,
+and the timer is reset to the specified interval
+(if the interval is nonzero).
+.P
+Three types of timers\[em]specified via the
+.I which
+argument\[em]are provided,
+each of which counts against a different clock and
+generates a different signal on timer expiration:
+.TP
+.B ITIMER_REAL
+This timer counts down in real (i.e., wall clock) time.
+At each expiration, a
+.B SIGALRM
+signal is generated.
+.TP
+.B ITIMER_VIRTUAL
+This timer counts down against the user-mode CPU time consumed by the process.
+(The measurement includes CPU time consumed by all threads in the process.)
+At each expiration, a
+.B SIGVTALRM
+signal is generated.
+.TP
+.B ITIMER_PROF
+This timer counts down against the total (i.e., both user and system)
+CPU time consumed by the process.
+(The measurement includes CPU time consumed by all threads in the process.)
+At each expiration, a
+.B SIGPROF
+signal is generated.
+.IP
+In conjunction with
+.BR ITIMER_VIRTUAL ,
+this timer can be used to profile user and system CPU time
+consumed by the process.
+.P
+A process has only one of each of the three types of timers.
+.P
+Timer values are defined by the following structures:
+.P
+.in +4n
+.EX
+struct itimerval {
+    struct timeval it_interval; /* Interval for periodic timer */
+    struct timeval it_value;    /* Time until next expiration */
+};
+\&
+struct timeval {
+    time_t      tv_sec;         /* seconds */
+    suseconds_t tv_usec;        /* microseconds */
+};
+.EE
+.in
+.\"
+.SS getitimer()
+The function
+.BR getitimer ()
+places the current value of the timer specified by
+.I which
+in the buffer pointed to by
+.IR curr_value .
+.P
+The
+.I it_value
+substructure is populated with the amount of time remaining until
+the next expiration of the specified timer.
+This value changes as the timer counts down, and will be reset to
+.I it_interval
+when the timer expires.
+If both fields of
+.I it_value
+are zero, then this timer is currently disarmed (inactive).
+.P
+The
+.I it_interval
+substructure is populated with the timer interval.
+If both fields of
+.I it_interval
+are zero, then this is a single-shot timer (i.e., it expires just once).
+.SS setitimer()
+The function
+.BR setitimer ()
+arms or disarms the timer specified by
+.IR which ,
+by setting the timer to the value specified by
+.IR new_value .
+If
+.I old_value
+is non-NULL,
+the buffer it points to is used to return the previous value of the timer
+(i.e., the same information that is returned by
+.BR getitimer ()).
+.P
+If either field in
+.I new_value.it_value
+is nonzero,
+then the timer is armed to initially expire at the specified time.
+If both fields in
+.I new_value.it_value
+are zero, then the timer is disarmed.
+.P
+The
+.I new_value.it_interval
+field specifies the new interval for the timer;
+if both of its subfields are zero, the timer is single-shot.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.IR new_value ,
+.IR old_value ,
+or
+.I curr_value
+is not valid a pointer.
+.TP
+.B EINVAL
+.I which
+is not one of
+.BR ITIMER_REAL ,
+.BR ITIMER_VIRTUAL ,
+or
+.BR ITIMER_PROF ;
+or (since Linux 2.6.22) one of the
+.I tv_usec
+fields in the structure pointed to by
+.I new_value
+contains a value outside the range [0, 999999].
+.SH VERSIONS
+The standards are silent on the meaning of the call:
+.P
+.in +4n
+.EX
+setitimer(which, NULL, &old_value);
+.EE
+.in
+.P
+Many systems (Solaris, the BSDs, and perhaps others)
+treat this as equivalent to:
+.P
+.in +4n
+.EX
+getitimer(which, &old_value);
+.EE
+.in
+.P
+In Linux, this is treated as being equivalent to a call in which the
+.I new_value
+fields are zero; that is, the timer is disabled.
+.IR "Don't use this Linux misfeature" :
+it is nonportable and unnecessary.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD (this call first appeared in 4.2BSD).
+POSIX.1-2008 marks
+.BR getitimer ()
+and
+.BR setitimer ()
+obsolete, recommending the use of the POSIX timers API
+.RB ( timer_gettime (2),
+.BR timer_settime (2),
+etc.) instead.
+.SH NOTES
+Timers will never expire before the requested time,
+but may expire some (short) time afterward, which depends
+on the system timer resolution and on the system load; see
+.BR time (7).
+(But see BUGS below.)
+If the timer expires while the process is active (always true for
+.BR ITIMER_VIRTUAL ),
+the signal will be delivered immediately when generated.
+.P
+A child created via
+.BR fork (2)
+does not inherit its parent's interval timers.
+Interval timers are preserved across an
+.BR execve (2).
+.P
+POSIX.1 leaves the
+interaction between
+.BR setitimer ()
+and the three interfaces
+.BR alarm (2),
+.BR sleep (3),
+and
+.BR usleep (3)
+unspecified.
+.SH BUGS
+The generation and delivery of a signal are distinct, and
+only one instance of each of the signals listed above may be pending
+for a process.
+Under very heavy loading, an
+.B ITIMER_REAL
+timer may expire before the signal from a previous expiration
+has been delivered.
+The second signal in such an event will be lost.
+.P
+Before Linux 2.6.16, timer values are represented in jiffies.
+If a request is made set a timer with a value whose jiffies
+representation exceeds
+.B MAX_SEC_IN_JIFFIES
+(defined in
+.IR include/linux/jiffies.h ),
+then the timer is silently truncated to this ceiling value.
+On Linux/i386 (where, since Linux 2.6.13,
+the default jiffy is 0.004 seconds),
+this means that the ceiling value for a timer is
+approximately 99.42 days.
+Since Linux 2.6.16,
+the kernel uses a different internal representation for times,
+and this ceiling is removed.
+.P
+On certain systems (including i386),
+Linux kernels before Linux 2.6.12 have a bug which will produce
+premature timer expirations of up to one jiffy under some circumstances.
+This bug is fixed in Linux 2.6.12.
+.\" 4 Jul 2005: It looks like this bug may remain in Linux 2.4.x.
+.\"	http://lkml.org/lkml/2005/7/1/165
+.P
+POSIX.1-2001 says that
+.BR setitimer ()
+should fail if a
+.I tv_usec
+value is specified that is outside of the range [0, 999999].
+However, up to and including Linux 2.6.21,
+Linux does not give an error, but instead silently
+adjusts the corresponding seconds value for the timer.
+From Linux 2.6.22 onward,
+this nonconformance has been repaired:
+an improper
+.I tv_usec
+value results in an
+.B EINVAL
+error.
+.\" Bugzilla report 25 Apr 2006:
+.\" http://bugzilla.kernel.org/show_bug.cgi?id=6443
+.\" "setitimer() should reject noncanonical arguments"
+.SH SEE ALSO
+.BR gettimeofday (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR timer_create (2),
+.BR timerfd_create (2),
+.BR time (7)
diff --git a/man/man2/getmsg.2 b/man/man2/getmsg.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/getmsg.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/getpagesize.2 b/man/man2/getpagesize.2
new file mode 100644
index 000000000..fcdac938a
--- /dev/null
+++ b/man/man2/getpagesize.2
@@ -0,0 +1,67 @@
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getpagesize 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpagesize \- get memory page size
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B int getpagesize(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getpagesize ():
+.nf
+    Since glibc 2.20:
+        _DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
+    glibc 2.12 to glibc 2.19:
+        _BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
+    Before glibc 2.12:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+The function
+.BR getpagesize ()
+returns the number of bytes in a memory page,
+where "page" is a fixed-length block,
+the unit for memory allocation and file mapping performed by
+.BR mmap (2).
+.SH VERSIONS
+A user program should not hard-code a page size,
+neither as a literal nor using the
+.B PAGE_SIZE
+macro,
+because some architectures support multiple page sizes.
+.P
+This manual page is in section 2 because
+Alpha, SPARC, and SPARC64
+all have a Linux system call
+.BR getpagesize ()
+though other architectures do not,
+and use the ELF auxiliary vector instead.
+.SH STANDARDS
+None.
+.SH HISTORY
+This call first appeared in 4.2BSD.
+SVr4, 4.4BSD, SUSv2.
+In SUSv2 the
+.BR getpagesize ()
+call was labeled LEGACY,
+and it was removed in POSIX.1-2001.
+.P
+glibc 2.0 returned a constant
+even on architectures with multiple page sizes.
+.SH SEE ALSO
+.BR mmap (2),
+.BR sysconf (3)
diff --git a/man/man2/getpeername.2 b/man/man2/getpeername.2
new file mode 100644
index 000000000..dc216c0f6
--- /dev/null
+++ b/man/man2/getpeername.2
@@ -0,0 +1,116 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)getpeername.2	6.5 (Berkeley) 3/10/91
+.\"
+.\" Modified Sat Jul 24 16:37:50 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Thu Jul 30 14:37:50 1993 by Martin Schulze <joey@debian.org>
+.\" Modified Sun Mar 28 21:26:46 1999 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 17 Jul 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added 'socket' to NAME, so that "man -k socket" will show this page.
+.\"
+.TH getpeername 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpeername \- get name of connected peer socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int getpeername(int " sockfd ", struct sockaddr *restrict " addr ,
+.BI "                socklen_t *restrict " addrlen );
+.fi
+.SH DESCRIPTION
+.BR getpeername ()
+returns the address of the peer connected to the socket
+.IR sockfd ,
+in the buffer pointed to by
+.IR addr .
+The
+.I addrlen
+argument should be initialized to indicate the amount of space pointed to
+by
+.IR addr .
+On return it contains the actual size of the name returned (in bytes).
+The name is truncated if the buffer provided is too small.
+.P
+The returned address is truncated if the buffer provided is too small;
+in this case,
+.I addrlen
+will return a value greater than was supplied to the call.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The argument
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+The
+.I addr
+argument points to memory not in a valid part of the
+process address space.
+.TP
+.B EINVAL
+.I addrlen
+is invalid (e.g., is negative).
+.TP
+.B ENOBUFS
+Insufficient resources were available in the system
+to perform the operation.
+.TP
+.B ENOTCONN
+The socket is not connected.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD
+(first appeared in 4.2BSD).
+.SH NOTES
+For stream sockets, once a
+.BR connect (2)
+has been performed, either socket can call
+.BR getpeername ()
+to obtain the address of the peer socket.
+On the other hand, datagram sockets are connectionless.
+Calling
+.BR connect (2)
+on a datagram socket merely sets the peer address for outgoing
+datagrams sent with
+.BR write (2)
+or
+.BR recv (2).
+The caller of
+.BR connect (2)
+can use
+.BR getpeername ()
+to obtain the peer address that it earlier set for the socket.
+However, the peer socket is unaware of this information, and calling
+.BR getpeername ()
+on the peer socket will return no useful information (unless a
+.BR connect (2)
+call was also executed on the peer).
+Note also that the receiver of a datagram can obtain
+the address of the sender when using
+.BR recvfrom (2).
+.SH SEE ALSO
+.BR accept (2),
+.BR bind (2),
+.BR getsockname (2),
+.BR ip (7),
+.BR socket (7),
+.BR unix (7)
diff --git a/man/man2/getpgid.2 b/man/man2/getpgid.2
new file mode 100644
index 000000000..d6b107a1c
--- /dev/null
+++ b/man/man2/getpgid.2
@@ -0,0 +1 @@
+.so man2/setpgid.2
diff --git a/man/man2/getpgrp.2 b/man/man2/getpgrp.2
new file mode 100644
index 000000000..d6b107a1c
--- /dev/null
+++ b/man/man2/getpgrp.2
@@ -0,0 +1 @@
+.so man2/setpgid.2
diff --git a/man/man2/getpid.2 b/man/man2/getpid.2
new file mode 100644
index 000000000..811270f05
--- /dev/null
+++ b/man/man2/getpid.2
@@ -0,0 +1,150 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getpid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpid, getppid \- get process identification
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B pid_t getpid(void);
+.B pid_t getppid(void);
+.fi
+.SH DESCRIPTION
+.BR getpid ()
+returns the process ID (PID) of the calling process.
+(This is often used by
+routines that generate unique temporary filenames.)
+.P
+.BR getppid ()
+returns the process ID of the parent of the calling process.
+This will be either the ID of the process that created this process using
+.BR fork (),
+or, if that process has already terminated,
+the ID of the process to which this process has been reparented (either
+.BR init (1)
+or a "subreaper" process defined via the
+.BR prctl (2)
+.B PR_SET_CHILD_SUBREAPER
+operation).
+.SH ERRORS
+These functions are always successful.
+.SH VERSIONS
+On Alpha, instead of a pair of
+.BR getpid ()
+and
+.BR getppid ()
+system calls, a single
+.BR getxpid ()
+system call is provided, which returns a pair of PID and parent PID.
+The glibc
+.BR getpid ()
+and
+.BR getppid ()
+wrapper functions transparently deal with this.
+See
+.BR syscall (2)
+for details regarding register mapping.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD, SVr4.
+.SS C library/kernel differences
+From glibc 2.3.4 up to and including glibc 2.24,
+the glibc wrapper function for
+.BR getpid ()
+cached PIDs,
+with the goal of avoiding additional system calls when a process calls
+.BR getpid ()
+repeatedly.
+Normally this caching was invisible,
+but its correct operation relied on support in the wrapper functions for
+.BR fork (2),
+.BR vfork (2),
+and
+.BR clone (2):
+if an application bypassed the glibc wrappers for these system calls by using
+.BR syscall (2),
+then a call to
+.BR getpid ()
+in the child would return the wrong value
+(to be precise: it would return the PID of the parent process).
+.\" The following program demonstrates this "feature":
+.\"
+.\" #define _GNU_SOURCE
+.\" #include <sys/syscall.h>
+.\" #include <sys/wait.h>
+.\" #include <stdint.h>
+.\" #include <stdio.h>
+.\" #include <stdlib.h>
+.\" #include <unistd.h>
+.\"
+.\" int
+.\" main(int argc, char *argv[])
+.\" {
+.\"    /* The following statement fills the getpid() cache */
+.\"
+.\"    printf("parent PID = %ld\n", (intmax_t) getpid());
+.\"
+.\"    if (syscall(SYS_fork) == 0) {
+.\"        if (getpid() != syscall(SYS_getpid))
+.\"            printf("child getpid() mismatch: getpid()=%jd; "
+.\"                    "syscall(SYS_getpid)=%ld\n",
+.\"                    (intmax_t) getpid(), (long) syscall(SYS_getpid));
+.\"        exit(EXIT_SUCCESS);
+.\"    }
+.\"    wait(NULL);
+.\"}
+In addition, there were cases where
+.BR getpid ()
+could return the wrong value even when invoking
+.BR clone (2)
+via the glibc wrapper function.
+(For a discussion of one such case, see BUGS in
+.BR clone (2).)
+Furthermore, the complexity of the caching code had been
+the source of a few bugs within glibc over the years.
+.P
+Because of the aforementioned problems,
+since glibc 2.25, the PID cache is removed:
+.\" commit c579f48edba88380635ab98cb612030e3ed8691e
+.\" https://sourceware.org/glibc/wiki/Release/2.25#pid_cache_removal
+calls to
+.BR getpid ()
+always invoke the actual system call, rather than returning a cached value.
+.\" FIXME .
+.\" Review progress of https://bugzilla.redhat.com/show_bug.cgi?id=1469757
+.SH NOTES
+If the caller's parent is in a different PID namespace (see
+.BR pid_namespaces (7)),
+.BR getppid ()
+returns 0.
+.P
+From a kernel perspective,
+the PID (which is shared by all of the threads in a multithreaded process)
+is sometimes also known as the thread group ID (TGID).
+This contrasts with the kernel thread ID (TID),
+which is unique for each thread.
+For further details, see
+.BR gettid (2)
+and the discussion of the
+.B CLONE_THREAD
+flag in
+.BR clone (2).
+.SH SEE ALSO
+.BR clone (2),
+.BR fork (2),
+.BR gettid (2),
+.BR kill (2),
+.BR exec (3),
+.BR mkstemp (3),
+.BR tempnam (3),
+.BR tmpfile (3),
+.BR tmpnam (3),
+.BR credentials (7),
+.BR pid_namespaces (7)
diff --git a/man/man2/getpmsg.2 b/man/man2/getpmsg.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/getpmsg.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/getppid.2 b/man/man2/getppid.2
new file mode 100644
index 000000000..fca885ee4
--- /dev/null
+++ b/man/man2/getppid.2
@@ -0,0 +1 @@
+.so man2/getpid.2
diff --git a/man/man2/getpriority.2 b/man/man2/getpriority.2
new file mode 100644
index 000000000..111b591b5
--- /dev/null
+++ b/man/man2/getpriority.2
@@ -0,0 +1,209 @@
+.\" Copyright (c) 1980, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)getpriority.2	6.9 (Berkeley) 3/10/91
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-07-01 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 1996-11-06 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-10-21 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"    Corrected statement under EPERM to clarify privileges required
+.\" Modified 2002-06-21 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"    Clarified meaning of 0 value for 'who' argument
+.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH getpriority 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpriority, setpriority \- get/set program scheduling priority
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/resource.h>
+.P
+.BI "int getpriority(int " which ", id_t " who );
+.BI "int setpriority(int " which ", id_t " who ", int " prio );
+.fi
+.SH DESCRIPTION
+The scheduling priority of the process, process group, or user, as
+indicated by
+.I which
+and
+.I who
+is obtained with the
+.BR getpriority ()
+call and set with the
+.BR setpriority ()
+call.
+The process attribute dealt with by these system calls is
+the same attribute (also known as the "nice" value) that is dealt with by
+.BR nice (2).
+.P
+The value
+.I which
+is one of
+.BR PRIO_PROCESS ,
+.BR PRIO_PGRP ,
+or
+.BR PRIO_USER ,
+and
+.I who
+is interpreted relative to
+.I which
+(a process identifier for
+.BR PRIO_PROCESS ,
+process group
+identifier for
+.BR PRIO_PGRP ,
+and a user ID for
+.BR PRIO_USER ).
+A zero value for
+.I who
+denotes (respectively) the calling process, the process group of the
+calling process, or the real user ID of the calling process.
+.P
+The
+.I prio
+argument is a value in the range \-20 to 19 (but see NOTES below),
+with \-20 being the highest priority and 19 being the lowest priority.
+Attempts to set a priority outside this range
+are silently clamped to the range.
+The default priority is 0;
+lower values give a process a higher scheduling priority.
+.P
+The
+.BR getpriority ()
+call returns the highest priority (lowest numerical value)
+enjoyed by any of the specified processes.
+The
+.BR setpriority ()
+call sets the priorities of all of the specified processes
+to the specified value.
+.P
+Traditionally, only a privileged process could lower the nice value
+(i.e., set a higher priority).
+However, since Linux 2.6.12, an unprivileged process can decrease
+the nice value of a target process that has a suitable
+.B RLIMIT_NICE
+soft limit; see
+.BR getrlimit (2)
+for details.
+.SH RETURN VALUE
+On success,
+.BR getpriority ()
+returns the calling thread's nice value, which may be a negative number.
+On error, it returns \-1 and sets
+.I errno
+to indicate the error.
+.P
+Since a successful call to
+.BR getpriority ()
+can legitimately return the value \-1, it is necessary
+to clear
+.I errno
+prior to the
+call, then check
+.I errno
+afterward to determine
+if \-1 is an error or a legitimate value.
+.P
+.BR setpriority ()
+returns 0 on success.
+On failure, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The caller attempted to set a lower nice value
+(i.e., a higher process priority), but did not
+have the required privilege (on Linux: did not have the
+.B CAP_SYS_NICE
+capability).
+.TP
+.B EINVAL
+.I which
+was not one of
+.BR PRIO_PROCESS ,
+.BR PRIO_PGRP ,
+or
+.BR PRIO_USER .
+.TP
+.B EPERM
+A process was located, but its effective user ID did not match
+either the effective or the real user ID of the caller,
+and was not privileged (on Linux: did not have the
+.B CAP_SYS_NICE
+capability).
+But see NOTES below.
+.TP
+.B ESRCH
+No process was located using the
+.I which
+and
+.I who
+values specified.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001,
+SVr4, 4.4BSD (these interfaces first appeared in 4.2BSD).
+.SH NOTES
+For further details on the nice value, see
+.BR sched (7).
+.P
+.IR Note :
+the addition of the "autogroup" feature in Linux 2.6.38 means that
+the nice value no longer has its traditional effect in many circumstances.
+For details, see
+.BR sched (7).
+.P
+A child created by
+.BR fork (2)
+inherits its parent's nice value.
+The nice value is preserved across
+.BR execve (2).
+.P
+The details on the condition for
+.B EPERM
+depend on the system.
+The above description is what POSIX.1-2001 says, and seems to be followed on
+all System\ V-like systems.
+Linux kernels before Linux 2.6.12 required the real or
+effective user ID of the caller to match
+the real user of the process \fIwho\fP (instead of its effective user ID).
+Linux 2.6.12 and later require
+the effective user ID of the caller to match
+the real or effective user ID of the process \fIwho\fP.
+All BSD-like systems (SunOS 4.1.3, Ultrix 4.2,
+4.3BSD, FreeBSD 4.3, OpenBSD-2.5, ...) behave in the same
+manner as Linux 2.6.12 and later.
+.\"
+.SS C library/kernel differences
+The getpriority system call returns nice values translated to the range 40..1,
+since a negative return value would be interpreted as an error.
+The glibc wrapper function for
+.BR getpriority ()
+translates the value back according to the formula
+.I unice\~=\~20\~\-\~knice
+(thus, the 40..1 range returned by the kernel
+corresponds to the range \-20..19 as seen by user space).
+.SH BUGS
+According to POSIX, the nice value is a per-process setting.
+However, under the current Linux/NPTL implementation of POSIX threads,
+the nice value is a per-thread attribute:
+different threads in the same process can have different nice values.
+Portable applications should avoid relying on the Linux behavior,
+which may be made standards conformant in the future.
+.SH SEE ALSO
+.BR nice (1),
+.BR renice (1),
+.BR fork (2),
+.BR capabilities (7),
+.BR sched (7)
+.P
+.I Documentation/scheduler/sched\-nice\-design.txt
+in the Linux kernel source tree (since Linux 2.6.23)
diff --git a/man/man2/getrandom.2 b/man/man2/getrandom.2
new file mode 100644
index 000000000..a6489a494
--- /dev/null
+++ b/man/man2/getrandom.2
@@ -0,0 +1,295 @@
+.\" Copyright (C) 2014, Theodore Ts'o <tytso@mit.edu>
+.\" Copyright (C) 2014,2015 Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\" Copyright (C) 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getrandom 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getrandom \- obtain a series of random bytes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/random.h>
+.P
+.BI "ssize_t getrandom(void " buf [. buflen "], size_t " buflen ", \
+unsigned int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR getrandom ()
+system call fills the buffer pointed to by
+.I buf
+with up to
+.I buflen
+random bytes.
+These bytes can be used to seed user-space random number generators
+or for cryptographic purposes.
+.P
+By default,
+.BR getrandom ()
+draws entropy from the
+.I urandom
+source (i.e., the same source as the
+.I /dev/urandom
+device).
+This behavior can be changed via the
+.I flags
+argument.
+.P
+If the
+.I urandom
+source has been initialized,
+reads of up to 256 bytes will always return as many bytes as
+requested and will not be interrupted by signals.
+No such guarantees apply for larger buffer sizes.
+For example, if the call is interrupted by a signal handler,
+it may return a partially filled buffer, or fail with the error
+.BR EINTR .
+.P
+If the
+.I urandom
+source has not yet been initialized, then
+.BR getrandom ()
+will block, unless
+.B GRND_NONBLOCK
+is specified in
+.IR flags .
+.P
+The
+.I flags
+argument is a bit mask that can contain zero or more of the following values
+ORed together:
+.TP
+.B GRND_RANDOM
+If this bit is set, then random bytes are drawn from the
+.I random
+source
+(i.e., the same source as the
+.I /dev/random
+device)
+instead of the
+.I urandom
+source.
+The
+.I random
+source is limited based on the entropy that can be obtained from environmental
+noise.
+If the number of available bytes in the
+.I random
+source is less than requested in
+.IR buflen ,
+the call returns just the available random bytes.
+If no random bytes are available, the behavior depends on the presence of
+.B GRND_NONBLOCK
+in the
+.I flags
+argument.
+.TP
+.B GRND_NONBLOCK
+By default, when reading from the
+.I random
+source,
+.BR getrandom ()
+blocks if no random bytes are available,
+and when reading from the
+.I urandom
+source, it blocks if the entropy pool has not yet been initialized.
+If the
+.B GRND_NONBLOCK
+flag is set, then
+.BR getrandom ()
+does not block in these cases, but instead immediately returns \-1 with
+.I errno
+set to
+.BR EAGAIN .
+.SH RETURN VALUE
+On success,
+.BR getrandom ()
+returns the number of bytes that were copied to the buffer
+.IR buf .
+This may be less than the number of bytes requested via
+.I buflen
+if either
+.B GRND_RANDOM
+was specified in
+.I flags
+and insufficient entropy was present in the
+.I random
+source or the system call was interrupted by a signal.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The requested entropy was not available, and
+.BR getrandom ()
+would have blocked if the
+.B GRND_NONBLOCK
+flag was not set.
+.TP
+.B EFAULT
+The address referred to by
+.I buf
+is outside the accessible address space.
+.TP
+.B EINTR
+The call was interrupted by a signal
+handler; see the description of how interrupted
+.BR read (2)
+calls on "slow" devices are handled with and without the
+.B SA_RESTART
+flag in the
+.BR signal (7)
+man page.
+.TP
+.B EINVAL
+An invalid flag was specified in
+.IR flags .
+.TP
+.B ENOSYS
+The glibc wrapper function for
+.BR getrandom ()
+determined that the underlying kernel does not implement this system call.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.17,
+glibc 2.25.
+.SH NOTES
+For an overview and comparison of the various interfaces that
+can be used to obtain randomness, see
+.BR random (7).
+.P
+Unlike
+.I /dev/random
+and
+.IR /dev/urandom ,
+.BR getrandom ()
+does not involve the use of pathnames or file descriptors.
+Thus,
+.BR getrandom ()
+can be useful in cases where
+.BR chroot (2)
+makes
+.I /dev
+pathnames invisible,
+and where an application (e.g., a daemon during start-up)
+closes a file descriptor for one of these files
+that was opened by a library.
+.\"
+.SS Maximum number of bytes returned
+As of Linux 3.19 the following limits apply:
+.IP \[bu] 3
+When reading from the
+.I urandom
+source, a maximum of 32Mi-1 bytes is returned by a single call to
+.BR getrandom ()
+on systems where
+.I int
+has a size of 32 bits.
+.IP \[bu]
+When reading from the
+.I random
+source, a maximum of 512 bytes is returned.
+.SS Interruption by a signal handler
+When reading from the
+.I urandom
+source
+.RB ( GRND_RANDOM
+is not set),
+.BR getrandom ()
+will block until the entropy pool has been initialized
+(unless the
+.B GRND_NONBLOCK
+flag was specified).
+If a request is made to read a large number of bytes (more than 256),
+.BR getrandom ()
+will block until those bytes have been generated and transferred
+from kernel memory to
+.IR buf .
+When reading from the
+.I random
+source
+.RB ( GRND_RANDOM
+is set),
+.BR getrandom ()
+will block until some random bytes become available
+(unless the
+.B GRND_NONBLOCK
+flag was specified).
+.P
+The behavior when a call to
+.BR getrandom ()
+that is blocked while reading from the
+.I urandom
+source is interrupted by a signal handler
+depends on the initialization state of the entropy buffer
+and on the request size,
+.IR buflen .
+If the entropy is not yet initialized, then the call fails with the
+.B EINTR
+error.
+If the entropy pool has been initialized
+and the request size is large
+.RI ( buflen "\ >\ 256),"
+the call either succeeds, returning a partially filled buffer,
+or fails with the error
+.BR EINTR .
+If the entropy pool has been initialized and the request size is small
+.RI ( buflen "\ <=\ 256),"
+then
+.BR getrandom ()
+will not fail with
+.BR EINTR .
+Instead, it will return all of the bytes that have been requested.
+.P
+When reading from the
+.I random
+source, blocking requests of any size can be interrupted by a signal handler
+(the call fails with the error
+.BR EINTR ).
+.P
+Using
+.BR getrandom ()
+to read small buffers (<=\ 256 bytes) from the
+.I urandom
+source is the preferred mode of usage.
+.P
+The special treatment of small values of
+.I buflen
+was designed for compatibility with
+OpenBSD's
+.BR getentropy (3),
+which is nowadays supported by glibc.
+.P
+The user of
+.BR getrandom ()
+.I must
+always check the return value,
+to determine whether either an error occurred
+or fewer bytes than requested were returned.
+In the case where
+.B GRND_RANDOM
+is not specified and
+.I buflen
+is less than or equal to 256,
+a return of fewer bytes than requested should never happen,
+but the careful programmer will check for this anyway!
+.SH BUGS
+As of Linux 3.19, the following bug exists:
+.\" FIXME patch proposed https://lkml.org/lkml/2014/11/29/16
+.IP \[bu] 3
+Depending on CPU load,
+.BR getrandom ()
+does not react to interrupts before reading all bytes requested.
+.SH SEE ALSO
+.BR getentropy (3),
+.BR random (4),
+.BR urandom (4),
+.BR random (7),
+.BR signal (7)
diff --git a/man/man2/getresgid.2 b/man/man2/getresgid.2
new file mode 100644
index 000000000..ac4fb7cb8
--- /dev/null
+++ b/man/man2/getresgid.2
@@ -0,0 +1 @@
+.so man2/getresuid.2
diff --git a/man/man2/getresgid32.2 b/man/man2/getresgid32.2
new file mode 100644
index 000000000..2b3240fa4
--- /dev/null
+++ b/man/man2/getresgid32.2
@@ -0,0 +1 @@
+.so man2/getresgid.2
diff --git a/man/man2/getresuid.2 b/man/man2/getresuid.2
new file mode 100644
index 000000000..b39bf5b7f
--- /dev/null
+++ b/man/man2/getresuid.2
@@ -0,0 +1,70 @@
+.\" Copyright (C) 1997 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (c) 2007, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified, 2003-05-26, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"
+.TH getresuid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getresuid, getresgid \- get real, effective, and saved user/group IDs
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BI "int getresuid(uid_t *" ruid ", uid_t *" euid ", uid_t *" suid );
+.BI "int getresgid(gid_t *" rgid ", gid_t *" egid ", gid_t *" sgid );
+.fi
+.SH DESCRIPTION
+.BR getresuid ()
+returns the real UID, the effective UID, and the saved set-user-ID
+of the calling process, in the arguments
+.IR ruid ,
+.IR euid ,
+and
+.IR suid ,
+respectively.
+.BR getresgid ()
+performs the analogous task for the process's group IDs.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+One of the arguments specified an address outside the calling program's
+address space.
+.SH STANDARDS
+None.
+These calls also appear on HP-UX and some of the BSDs.
+.SH HISTORY
+Linux 2.1.44,
+glibc 2.3.2.
+.P
+The original Linux
+.BR getresuid ()
+and
+.BR getresgid ()
+system calls supported only 16-bit user and group IDs.
+Subsequently, Linux 2.4 added
+.BR getresuid32 ()
+and
+.BR getresgid32 (),
+supporting 32-bit IDs.
+The glibc
+.BR getresuid ()
+and
+.BR getresgid ()
+wrapper functions transparently deal with the variations across kernel versions.
+.SH SEE ALSO
+.BR getuid (2),
+.BR setresuid (2),
+.BR setreuid (2),
+.BR setuid (2),
+.BR credentials (7)
diff --git a/man/man2/getresuid32.2 b/man/man2/getresuid32.2
new file mode 100644
index 000000000..ac4fb7cb8
--- /dev/null
+++ b/man/man2/getresuid32.2
@@ -0,0 +1 @@
+.so man2/getresuid.2
diff --git a/man/man2/getrlimit.2 b/man/man2/getrlimit.2
new file mode 100644
index 000000000..b1254f618
--- /dev/null
+++ b/man/man2/getrlimit.2
@@ -0,0 +1,853 @@
+'\" t
+.\" Copyright (c) 1992 Drew Eckhardt, March 28, 1992
+.\" and Copyright (c) 2002, 2004, 2005, 2008, 2010 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-23 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-01-13 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 1996-01-22 by aeb, following a remark by
+.\"          Tigran Aivazian <tigran@sco.com>
+.\" Modified 1996-04-14 by aeb, following a remark by
+.\"          Robert Bihlmeyer <robbe@orcus.ping.at>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-05-04 by aeb, following a remark by
+.\"          Håvard Lygre <hklygre@online.no>
+.\" Modified 2001-04-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2002-06-13 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added note on nonstandard behavior when SIGCHLD is ignored.
+.\" Modified 2002-07-09 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Enhanced descriptions of 'resource' values
+.\" Modified 2003-11-28 by aeb, added RLIMIT_CORE
+.\" Modified 2004-03-26 by aeb, added RLIMIT_AS
+.\" Modified 2004-06-16 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on CAP_SYS_RESOURCE
+.\"
+.\" 2004-11-16 -- mtk: the getrlimit.2 page, which formally included
+.\" coverage of getrusage(2), has been split, so that the latter
+.\" is now covered in its own getrusage.2.
+.\"
+.\" Modified 2004-11-16, mtk: A few other minor changes
+.\" Modified 2004-11-23, mtk
+.\"	Added notes on RLIMIT_MEMLOCK, RLIMIT_NPROC, and RLIMIT_RSS
+.\"		to "CONFORMING TO"
+.\" Modified 2004-11-25, mtk
+.\"	Rewrote discussion on RLIMIT_MEMLOCK to incorporate kernel
+.\"		2.6.9 changes.
+.\"	Added note on RLIMIT_CPU error in older kernels
+.\" 2004-11-03, mtk, Added RLIMIT_SIGPENDING
+.\" 2005-07-13, mtk, documented RLIMIT_MSGQUEUE limit.
+.\" 2005-07-28, mtk, Added descriptions of RLIMIT_NICE and RLIMIT_RTPRIO
+.\" 2008-05-07, mtk / Peter Zijlstra, Added description of RLIMIT_RTTIME
+.\" 2010-11-06, mtk: Added documentation of prlimit()
+.\"
+.TH getrlimit 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getrlimit, setrlimit, prlimit \- get/set resource limits
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/resource.h>
+.P
+.BI "int getrlimit(int " resource ", struct rlimit *" rlim );
+.BI "int setrlimit(int " resource ", const struct rlimit *" rlim );
+.P
+.BI "int prlimit(pid_t "  pid ", int " resource ,
+.BI "            const struct rlimit *_Nullable " new_limit ,
+.BI "            struct rlimit *_Nullable " old_limit );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR prlimit ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getrlimit ()
+and
+.BR setrlimit ()
+system calls get and set resource limits.
+Each resource has an associated soft and hard limit, as defined by the
+.I rlimit
+structure:
+.P
+.in +4n
+.EX
+struct rlimit {
+    rlim_t rlim_cur;  /* Soft limit */
+    rlim_t rlim_max;  /* Hard limit (ceiling for rlim_cur) */
+};
+.EE
+.in
+.P
+The soft limit is the value that the kernel enforces for the
+corresponding resource.
+The hard limit acts as a ceiling for the soft limit:
+an unprivileged process may set only its soft limit to a value in the
+range from 0 up to the hard limit, and (irreversibly) lower its hard limit.
+A privileged process (under Linux: one with the
+.B CAP_SYS_RESOURCE
+capability in the initial user namespace)
+may make arbitrary changes to either limit value.
+.P
+The value
+.B RLIM_INFINITY
+denotes no limit on a resource (both in the structure returned by
+.BR getrlimit ()
+and in the structure passed to
+.BR setrlimit ()).
+.P
+The
+.I resource
+argument must be one of:
+.TP
+.B RLIMIT_AS
+This is the maximum size of the process's virtual memory
+(address space).
+The limit is specified in bytes, and is rounded down to the system page size.
+.\" since Linux 2.0.27 / Linux 2.1.12
+This limit affects calls to
+.BR brk (2),
+.BR mmap (2),
+and
+.BR mremap (2),
+which fail with the error
+.B ENOMEM
+upon exceeding this limit.
+In addition, automatic stack expansion fails
+(and generates a
+.B SIGSEGV
+that kills the process if no alternate stack
+has been made available via
+.BR sigaltstack (2)).
+Since the value is a \fIlong\fP, on machines with a 32-bit \fIlong\fP
+either this limit is at most 2\ GiB, or this resource is unlimited.
+.TP
+.B RLIMIT_CORE
+This is the maximum size of a
+.I core
+file (see
+.BR core (5))
+in bytes that the process may dump.
+When 0 no core dump files are created.
+When nonzero, larger dumps are truncated to this size.
+.TP
+.B RLIMIT_CPU
+This is a limit, in seconds,
+on the amount of CPU time that the process can consume.
+When the process reaches the soft limit, it is sent a
+.B SIGXCPU
+signal.
+The default action for this signal is to terminate the process.
+However, the signal can be caught, and the handler can return control to
+the main program.
+If the process continues to consume CPU time, it will be sent
+.B SIGXCPU
+once per second until the hard limit is reached, at which time
+it is sent
+.BR SIGKILL .
+(This latter point describes Linux behavior.
+Implementations vary in how they treat processes which continue to
+consume CPU time after reaching the soft limit.
+Portable applications that need to catch this signal should
+perform an orderly termination upon first receipt of
+.BR SIGXCPU .)
+.TP
+.B RLIMIT_DATA
+This is the maximum size
+of the process's data segment (initialized data,
+uninitialized data, and heap).
+The limit is specified in bytes, and is rounded down to the system page size.
+This limit affects calls to
+.BR brk (2),
+.BR sbrk (2),
+and (since Linux 4.7)
+.BR mmap (2),
+.\" commits 84638335900f1995495838fe1bd4870c43ec1f67
+.\" ("mm: rework virtual memory accounting"),
+.\" f4fcd55841fc9e46daac553b39361572453c2b88
+.\" (mm: enable RLIMIT_DATA by default with workaround for valgrind).
+which fail with the error
+.B ENOMEM
+upon encountering the soft limit of this resource.
+.TP
+.B RLIMIT_FSIZE
+This is the maximum size in bytes of files that the process may create.
+Attempts to extend a file beyond this limit result in delivery of a
+.B SIGXFSZ
+signal.
+By default, this signal terminates a process, but a process can
+catch this signal instead, in which case the relevant system call (e.g.,
+.BR write (2),
+.BR truncate (2))
+fails with the error
+.BR EFBIG .
+.TP
+.BR RLIMIT_LOCKS " (Linux 2.4.0 to Linux 2.4.24)"
+.\" to be precise: Linux 2.4.0-test9; no longer in Linux 2.4.25 / Linux 2.5.65
+This is a limit on the combined number of
+.BR flock (2)
+locks and
+.BR fcntl (2)
+leases that this process may establish.
+.TP
+.B RLIMIT_MEMLOCK
+This is the maximum number of bytes of memory that may be locked
+into RAM.
+This limit is in effect rounded down to the nearest multiple
+of the system page size.
+This limit affects
+.BR mlock (2),
+.BR mlockall (2),
+and the
+.BR mmap (2)
+.B MAP_LOCKED
+operation.
+Since Linux 2.6.9, it also affects the
+.BR shmctl (2)
+.B SHM_LOCK
+operation, where it sets a maximum on the total bytes in
+shared memory segments (see
+.BR shmget (2))
+that may be locked by the real user ID of the calling process.
+The
+.BR shmctl (2)
+.B SHM_LOCK
+locks are accounted for separately from the per-process memory
+locks established by
+.BR mlock (2),
+.BR mlockall (2),
+and
+.BR mmap (2)
+.BR MAP_LOCKED ;
+a process can lock bytes up to this limit in each of these
+two categories.
+.IP
+Before Linux 2.6.9, this limit controlled the amount of
+memory that could be locked by a privileged process.
+Since Linux 2.6.9, no limits are placed on the amount of memory
+that a privileged process may lock, and this limit instead governs
+the amount of memory that an unprivileged process may lock.
+.TP
+.BR RLIMIT_MSGQUEUE " (since Linux 2.6.8)"
+This is a limit on the number of bytes that can be allocated
+for POSIX message queues for the real user ID of the calling process.
+This limit is enforced for
+.BR mq_open (3).
+Each message queue that the user creates counts (until it is removed)
+against this limit according to the formula:
+.RS 4
+.IP
+Since Linux 3.5:
+.IP
+.in +4n
+.EX
+bytes = attr.mq_maxmsg * sizeof(struct msg_msg) +
+        MIN(attr.mq_maxmsg, MQ_PRIO_MAX) *
+              sizeof(struct posix_msg_tree_node)+
+                        /* For overhead */
+        attr.mq_maxmsg * attr.mq_msgsize;
+                        /* For message data */
+.EE
+.in
+.IP
+Linux 3.4 and earlier:
+.IP
+.in +4n
+.EX
+bytes = attr.mq_maxmsg * sizeof(struct msg_msg *) +
+                        /* For overhead */
+        attr.mq_maxmsg * attr.mq_msgsize;
+                        /* For message data */
+.EE
+.in
+.RE
+.IP
+where
+.I attr
+is the
+.I mq_attr
+structure specified as the fourth argument to
+.BR mq_open (3),
+and the
+.I msg_msg
+and
+.I posix_msg_tree_node
+structures are kernel-internal structures.
+.IP
+The "overhead" addend in the formula accounts for overhead
+bytes required by the implementation
+and ensures that the user cannot
+create an unlimited number of zero-length messages (such messages
+nevertheless each consume some system memory for bookkeeping overhead).
+.TP
+.BR RLIMIT_NICE " (since Linux 2.6.12, but see BUGS below)"
+This specifies a ceiling to which the process's nice value can be raised using
+.BR setpriority (2)
+or
+.BR nice (2).
+The actual ceiling for the nice value is calculated as
+.IR "20\ \-\ rlim_cur" .
+The useful range for this limit is thus from 1
+(corresponding to a nice value of 19) to 40
+(corresponding to a nice value of \-20).
+This unusual choice of range was necessary
+because negative numbers cannot be specified
+as resource limit values, since they typically have special meanings.
+For example,
+.B RLIM_INFINITY
+typically is the same as \-1.
+For more detail on the nice value, see
+.BR sched (7).
+.TP
+.B RLIMIT_NOFILE
+This specifies a value one greater than the maximum file descriptor number
+that can be opened by this process.
+Attempts
+.RB ( open (2),
+.BR pipe (2),
+.BR dup (2),
+etc.)
+to exceed this limit yield the error
+.BR EMFILE .
+(Historically, this limit was named
+.B RLIMIT_OFILE
+on BSD.)
+.IP
+Since Linux 4.5,
+this limit also defines the maximum number of file descriptors that
+an unprivileged process (one without the
+.B CAP_SYS_RESOURCE
+capability) may have "in flight" to other processes,
+by being passed across UNIX domain sockets.
+This limit applies to the
+.BR sendmsg (2)
+system call.
+For further details, see
+.BR unix (7).
+.TP
+.B RLIMIT_NPROC
+This is a limit on the number of extant process
+(or, more precisely on Linux, threads)
+for the real user ID of the calling process.
+So long as the current number of processes belonging to this
+process's real user ID is greater than or equal to this limit,
+.BR fork (2)
+fails with the error
+.BR EAGAIN .
+.IP
+The
+.B RLIMIT_NPROC
+limit is not enforced for processes that have either the
+.B CAP_SYS_ADMIN
+or the
+.B CAP_SYS_RESOURCE
+capability,
+or run with real user ID 0.
+.TP
+.B RLIMIT_RSS
+This is a limit (in bytes) on the process's resident set
+(the number of virtual pages resident in RAM).
+This limit has effect only in Linux 2.4.x, x < 30, and there
+affects only calls to
+.BR madvise (2)
+specifying
+.BR MADV_WILLNEED .
+.\" As at Linux 2.6.12, this limit still does nothing in Linux 2.6 though
+.\" talk of making it do something has surfaced from time to time in LKML
+.\"       -- MTK, Jul 05
+.TP
+.BR RLIMIT_RTPRIO " (since Linux 2.6.12, but see BUGS)"
+This specifies a ceiling on the real-time priority that may be set for
+this process using
+.BR sched_setscheduler (2)
+and
+.BR sched_setparam (2).
+.IP
+For further details on real-time scheduling policies, see
+.BR sched (7)
+.TP
+.BR RLIMIT_RTTIME " (since Linux 2.6.25)"
+This is a limit (in microseconds)
+on the amount of CPU time that a process scheduled
+under a real-time scheduling policy may consume without making a blocking
+system call.
+For the purpose of this limit,
+each time a process makes a blocking system call,
+the count of its consumed CPU time is reset to zero.
+The CPU time count is not reset if the process continues trying to
+use the CPU but is preempted, its time slice expires, or it calls
+.BR sched_yield (2).
+.IP
+Upon reaching the soft limit, the process is sent a
+.B SIGXCPU
+signal.
+If the process catches or ignores this signal and
+continues consuming CPU time, then
+.B SIGXCPU
+will be generated once each second until the hard limit is reached,
+at which point the process is sent a
+.B SIGKILL
+signal.
+.IP
+The intended use of this limit is to stop a runaway
+real-time process from locking up the system.
+.IP
+For further details on real-time scheduling policies, see
+.BR sched (7)
+.TP
+.BR RLIMIT_SIGPENDING " (since Linux 2.6.8)"
+This is a limit on the number of signals
+that may be queued for the real user ID of the calling process.
+Both standard and real-time signals are counted for the purpose of
+checking this limit.
+However, the limit is enforced only for
+.BR sigqueue (3);
+it is always possible to use
+.BR kill (2)
+to queue one instance of any of the signals that are not already
+queued to the process.
+.\" This replaces the /proc/sys/kernel/rtsig-max system-wide limit
+.\" that was present in Linux <= 2.6.7.  MTK Dec 04
+.TP
+.B RLIMIT_STACK
+This is the maximum size of the process stack, in bytes.
+Upon reaching this limit, a
+.B SIGSEGV
+signal is generated.
+To handle this signal, a process must employ an alternate signal stack
+.RB ( sigaltstack (2)).
+.IP
+Since Linux 2.6.23,
+this limit also determines the amount of space used for the process's
+command-line arguments and environment variables; for details, see
+.BR execve (2).
+.SS prlimit()
+.\" commit c022a0acad534fd5f5d5f17280f6d4d135e74e81
+.\" Author: Jiri Slaby <jslaby@suse.cz>
+.\" Date:   Tue May 4 18:03:50 2010 +0200
+.\"
+.\"     rlimits: implement prlimit64 syscall
+.\"
+.\" commit 6a1d5e2c85d06da35cdfd93f1a27675bfdc3ad8c
+.\" Author: Jiri Slaby <jslaby@suse.cz>
+.\" Date:   Wed Mar 24 17:06:58 2010 +0100
+.\"
+.\"     rlimits: add rlimit64 structure
+.\"
+The Linux-specific
+.BR prlimit ()
+system call combines and extends the functionality of
+.BR setrlimit ()
+and
+.BR getrlimit ().
+It can be used to both set and get the resource limits of an arbitrary process.
+.P
+The
+.I resource
+argument has the same meaning as for
+.BR setrlimit ()
+and
+.BR getrlimit ().
+.P
+If the
+.I new_limit
+argument is not NULL, then the
+.I rlimit
+structure to which it points is used to set new values for
+the soft and hard limits for
+.IR resource .
+If the
+.I old_limit
+argument is not NULL, then a successful call to
+.BR prlimit ()
+places the previous soft and hard limits for
+.I resource
+in the
+.I rlimit
+structure pointed to by
+.IR old_limit .
+.P
+The
+.I pid
+argument specifies the ID of the process on which the call is to operate.
+If
+.I pid
+is 0, then the call applies to the calling process.
+To set or get the resources of a process other than itself,
+the caller must have the
+.B CAP_SYS_RESOURCE
+capability in the user namespace of the process
+whose resource limits are being changed, or the
+real, effective, and saved set user IDs of the target process
+must match the real user ID of the caller
+.I and
+the real, effective, and saved set group IDs of the target process
+must match the real group ID of the caller.
+.\" FIXME . this permission check is strange
+.\" Asked about this on LKML, 7 Nov 2010
+.\"     "Inconsistent credential checking in prlimit() syscall"
+.SH RETURN VALUE
+On success, these system calls return 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+A pointer argument points to a location
+outside the accessible address space.
+.TP
+.B EINVAL
+The value specified in
+.I resource
+is not valid;
+or, for
+.BR setrlimit ()
+or
+.BR prlimit ():
+.I rlim\->rlim_cur
+was greater than
+.IR rlim\->rlim_max .
+.TP
+.B EPERM
+An unprivileged process tried to raise the hard limit; the
+.B CAP_SYS_RESOURCE
+capability is required to do this.
+.TP
+.B EPERM
+The caller tried to increase the hard
+.B RLIMIT_NOFILE
+limit above the maximum defined by
+.I /proc/sys/fs/nr_open
+(see
+.BR proc (5))
+.TP
+.B EPERM
+.RB ( prlimit ())
+The calling process did not have permission to set limits
+for the process specified by
+.IR pid .
+.TP
+.B ESRCH
+Could not find a process with the ID specified in
+.IR pid .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getrlimit (),
+.BR setrlimit (),
+.BR prlimit ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR getrlimit ()
+.TQ
+.BR setrlimit ()
+POSIX.1-2008.
+.TP
+.BR prlimit ()
+Linux.
+.P
+.B RLIMIT_MEMLOCK
+and
+.B RLIMIT_NPROC
+derive from BSD and are not specified in POSIX.1;
+they are present on the BSDs and Linux, but on few other implementations.
+.B RLIMIT_RSS
+derives from BSD and is not specified in POSIX.1;
+it is nevertheless present on most implementations.
+.BR \%RLIMIT_MSGQUEUE ,
+.BR RLIMIT_NICE ,
+.BR RLIMIT_RTPRIO ,
+.BR RLIMIT_RTTIME ,
+and
+.B \%RLIMIT_SIGPENDING
+are Linux-specific.
+.SH HISTORY
+.TP
+.BR getrlimit ()
+.TQ
+.BR setrlimit ()
+POSIX.1-2001, SVr4, 4.3BSD.
+.TP
+.BR prlimit ()
+Linux 2.6.36,
+glibc 2.13.
+.SH NOTES
+A child process created via
+.BR fork (2)
+inherits its parent's resource limits.
+Resource limits are preserved across
+.BR execve (2).
+.P
+Resource limits are per-process attributes that are shared
+by all of the threads in a process.
+.P
+Lowering the soft limit for a resource below the process's
+current consumption of that resource will succeed
+(but will prevent the process from further increasing
+its consumption of the resource).
+.P
+One can set the resource limits of the shell using the built-in
+.I ulimit
+command
+.RI ( limit
+in
+.BR csh (1)).
+The shell's resource limits are inherited by the processes that
+it creates to execute commands.
+.P
+Since Linux 2.6.24, the resource limits of any process can be inspected via
+.IR /proc/ pid /limits ;
+see
+.BR proc (5).
+.P
+Ancient systems provided a
+.BR vlimit ()
+function with a similar purpose to
+.BR setrlimit ().
+For backward compatibility, glibc also provides
+.BR vlimit ().
+All new applications should be written using
+.BR setrlimit ().
+.SS C library/kernel ABI differences
+Since glibc 2.13, the glibc
+.BR getrlimit ()
+and
+.BR setrlimit ()
+wrapper functions no longer invoke the corresponding system calls,
+but instead employ
+.BR prlimit (),
+for the reasons described in BUGS.
+.P
+The name of the glibc wrapper function is
+.BR prlimit ();
+the underlying system call is
+.BR prlimit64 ().
+.SH BUGS
+In older Linux kernels, the
+.B SIGXCPU
+and
+.B SIGKILL
+signals delivered when a process encountered the soft and hard
+.B RLIMIT_CPU
+limits were delivered one (CPU) second later than they should have been.
+This was fixed in Linux 2.6.8.
+.P
+In Linux 2.6.x kernels before Linux 2.6.17, a
+.B RLIMIT_CPU
+limit of 0 is wrongly treated as "no limit" (like
+.BR RLIM_INFINITY ).
+Since Linux 2.6.17, setting a limit of 0 does have an effect,
+but is actually treated as a limit of 1 second.
+.\" see http://marc.theaimsgroup.com/?l=linux-kernel&m=114008066530167&w=2
+.P
+A kernel bug means that
+.\" See https://lwn.net/Articles/145008/
+.B RLIMIT_RTPRIO
+does not work in Linux 2.6.12; the problem is fixed in Linux 2.6.13.
+.P
+In Linux 2.6.12, there was an off-by-one mismatch
+between the priority ranges returned by
+.BR getpriority (2)
+and
+.BR RLIMIT_NICE .
+This had the effect that the actual ceiling for the nice value
+was calculated as
+.IR "19\ \-\ rlim_cur" .
+This was fixed in Linux 2.6.13.
+.\" see http://marc.theaimsgroup.com/?l=linux-kernel&m=112256338703880&w=2
+.P
+Since Linux 2.6.12,
+.\" The relevant patch, sent to LKML, seems to be
+.\" http://thread.gmane.org/gmane.linux.kernel/273462
+.\" From: Roland McGrath <roland <at> redhat.com>
+.\" Subject: [PATCH 7/7] make RLIMIT_CPU/SIGXCPU per-process
+.\" Date: 2005-01-23 23:27:46 GMT
+if a process reaches its soft
+.B RLIMIT_CPU
+limit and has a handler installed for
+.BR SIGXCPU ,
+then, in addition to invoking the signal handler,
+the kernel increases the soft limit by one second.
+This behavior repeats if the process continues to consume CPU time,
+until the hard limit is reached,
+at which point the process is killed.
+Other implementations
+.\" Tested Solaris 10, FreeBSD 9, OpenBSD 5.0
+do not change the
+.B RLIMIT_CPU
+soft limit in this manner,
+and the Linux behavior is probably not standards conformant;
+portable applications should avoid relying on this Linux-specific behavior.
+.\" FIXME . https://bugzilla.kernel.org/show_bug.cgi?id=50951
+The Linux-specific
+.B RLIMIT_RTTIME
+limit exhibits the same behavior when the soft limit is encountered.
+.P
+Kernels before Linux 2.4.22 did not diagnose the error
+.B EINVAL
+for
+.BR setrlimit ()
+when
+.I rlim\->rlim_cur
+was greater than
+.IR rlim\->rlim_max .
+.\" d3561f78fd379a7110e46c87964ba7aa4120235c
+.P
+Linux doesn't return an error when an attempt to set
+.B RLIMIT_CPU
+has failed, for compatibility reasons.
+.\"
+.SS Representation of \[dq]large\[dq] resource limit values on 32-bit platforms
+The glibc
+.BR getrlimit ()
+and
+.BR setrlimit ()
+wrapper functions use a 64-bit
+.I rlim_t
+data type, even on 32-bit platforms.
+However, the
+.I rlim_t
+data type used in the
+.BR getrlimit ()
+and
+.BR setrlimit ()
+system calls is a (32-bit)
+.IR "unsigned long" .
+.\" Linux still uses long for limits internally:
+.\" c022a0acad534fd5f5d5f17280f6d4d135e74e81
+.\" kernel/sys.c:do_prlimit() still uses struct rlimit which
+.\" uses kernel_ulong_t for its members, i.e. 32-bit  on 32-bit kernel.
+Furthermore, in Linux,
+the kernel represents resource limits on 32-bit platforms as
+.IR "unsigned long" .
+However, a 32-bit data type is not wide enough.
+.\" https://bugzilla.kernel.org/show_bug.cgi?id=5042
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=12201
+The most pertinent limit here is
+.BR \%RLIMIT_FSIZE ,
+which specifies the maximum size to which a file can grow:
+to be useful, this limit must be represented using a type
+that is as wide as the type used to
+represent file offsets\[em]that is, as wide as a 64-bit
+.B off_t
+(assuming a program compiled with
+.IR _FILE_OFFSET_BITS=64 ).
+.P
+To work around this kernel limitation,
+if a program tried to set a resource limit to a value larger than
+can be represented in a 32-bit
+.IR "unsigned long" ,
+then the glibc
+.BR setrlimit ()
+wrapper function silently converted the limit value to
+.BR RLIM_INFINITY .
+In other words, the requested resource limit setting was silently ignored.
+.P
+Since glibc 2.13,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=12201
+glibc works around the limitations of the
+.BR \%getrlimit ()
+and
+.BR setrlimit ()
+system calls by implementing
+.BR setrlimit ()
+and
+.BR \%getrlimit ()
+as wrapper functions that call
+.BR prlimit ().
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR prlimit ().
+.P
+.\" SRC BEGIN (getrlimit.c)
+.EX
+#define _GNU_SOURCE
+#define _FILE_OFFSET_BITS 64
+#include <err.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/resource.h>
+#include <time.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    pid_t          pid;
+    struct rlimit  old, new;
+    struct rlimit  *newp;
+\&
+    if (!(argc == 2 || argc == 4)) {
+        fprintf(stderr, "Usage: %s <pid> [<new\-soft\-limit> "
+                "<new\-hard\-limit>]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    pid = atoi(argv[1]);        /* PID of target process */
+\&
+    newp = NULL;
+    if (argc == 4) {
+        new.rlim_cur = atoi(argv[2]);
+        new.rlim_max = atoi(argv[3]);
+        newp = &new;
+    }
+\&
+    /* Set CPU time limit of target process; retrieve and display
+       previous limit */
+\&
+    if (prlimit(pid, RLIMIT_CPU, newp, &old) == \-1)
+        err(EXIT_FAILURE, "prlimit\-1");
+    printf("Previous limits: soft=%jd; hard=%jd\en",
+           (intmax_t) old.rlim_cur, (intmax_t) old.rlim_max);
+\&
+    /* Retrieve and display new CPU time limit */
+\&
+    if (prlimit(pid, RLIMIT_CPU, NULL, &old) == \-1)
+        err(EXIT_FAILURE, "prlimit\-2");
+    printf("New limits: soft=%jd; hard=%jd\en",
+           (intmax_t) old.rlim_cur, (intmax_t) old.rlim_max);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR prlimit (1),
+.BR dup (2),
+.BR fcntl (2),
+.BR fork (2),
+.BR getrusage (2),
+.BR mlock (2),
+.BR mmap (2),
+.BR open (2),
+.BR quotactl (2),
+.BR sbrk (2),
+.BR shmctl (2),
+.BR malloc (3),
+.BR sigqueue (3),
+.BR ulimit (3),
+.BR core (5),
+.BR capabilities (7),
+.BR cgroups (7),
+.BR credentials (7),
+.BR signal (7)
diff --git a/man/man2/getrusage.2 b/man/man2/getrusage.2
new file mode 100644
index 000000000..2ae9dafa4
--- /dev/null
+++ b/man/man2/getrusage.2
@@ -0,0 +1,250 @@
+'\" t
+.\" Copyright (c) 1992 Drew Eckhardt, March 28, 1992
+.\" and Copyright (c) 2002 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2004-11-16 -- mtk: the getrlimit.2 page, which formerly included
+.\" coverage of getrusage(2), has been split, so that the latter is
+.\" now covered in its own getrusage.2.  For older details of change
+.\" history, etc., see getrlimit.2
+.\"
+.\" Modified 2004-11-16, mtk, Noted that the nonconformance
+.\"	when SIGCHLD is being ignored is fixed in Linux 2.6.9.
+.\" 2008-02-22, Sripathi Kodi <sripathik@in.ibm.com>: Document RUSAGE_THREAD
+.\" 2008-05-25, mtk, clarify RUSAGE_CHILDREN + other clean-ups.
+.\" 2010-05-24, Mark Hills <mark@pogo.org.uk>: Description of fields,
+.\"     document ru_maxrss
+.\" 2010-05-24, mtk, enhanced description of various fields
+.\"
+.TH getrusage 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getrusage \- get resource usage
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/resource.h>
+.P
+.BI "int getrusage(int " who ", struct rusage *" usage );
+.fi
+.SH DESCRIPTION
+.BR getrusage ()
+returns resource usage measures for
+.IR who ,
+which can be one of the following:
+.TP
+.B RUSAGE_SELF
+Return resource usage statistics for the calling process,
+which is the sum of resources used by all threads in the process.
+.TP
+.B RUSAGE_CHILDREN
+Return resource usage statistics for all children of the
+calling process that have terminated and been waited for.
+These statistics will include the resources used by grandchildren,
+and further removed descendants,
+if all of the intervening descendants waited on their terminated children.
+.TP
+.BR RUSAGE_THREAD " (since Linux 2.6.26)"
+Return resource usage statistics for the calling thread.
+The
+.B _GNU_SOURCE
+feature test macro must be defined (before including
+.I any
+header file)
+in order to obtain the definition of this constant from
+.IR <sys/resource.h> .
+.P
+The resource usages are returned in the structure pointed to by
+.IR usage ,
+which has the following form:
+.P
+.in +4n
+.EX
+struct rusage {
+    struct timeval ru_utime; /* user CPU time used */
+    struct timeval ru_stime; /* system CPU time used */
+    long   ru_maxrss;        /* maximum resident set size */
+    long   ru_ixrss;         /* integral shared memory size */
+    long   ru_idrss;         /* integral unshared data size */
+    long   ru_isrss;         /* integral unshared stack size */
+    long   ru_minflt;        /* page reclaims (soft page faults) */
+    long   ru_majflt;        /* page faults (hard page faults) */
+    long   ru_nswap;         /* swaps */
+    long   ru_inblock;       /* block input operations */
+    long   ru_oublock;       /* block output operations */
+    long   ru_msgsnd;        /* IPC messages sent */
+    long   ru_msgrcv;        /* IPC messages received */
+    long   ru_nsignals;      /* signals received */
+    long   ru_nvcsw;         /* voluntary context switches */
+    long   ru_nivcsw;        /* involuntary context switches */
+};
+.EE
+.in
+.P
+Not all fields are completed;
+unmaintained fields are set to zero by the kernel.
+(The unmaintained fields are provided for compatibility with other systems,
+and because they may one day be supported on Linux.)
+The fields are interpreted as follows:
+.TP
+.I ru_utime
+This is the total amount of time spent executing in user mode,
+expressed in a
+.I timeval
+structure (seconds plus microseconds).
+.TP
+.I ru_stime
+This is the total amount of time spent executing in kernel mode,
+expressed in a
+.I timeval
+structure (seconds plus microseconds).
+.TP
+.IR ru_maxrss " (since Linux 2.6.32)"
+This is the maximum resident set size used (in kilobytes).
+For
+.BR RUSAGE_CHILDREN ,
+this is the resident set size of the largest child, not the maximum
+resident set size of the process tree.
+.TP
+.IR ru_ixrss " (unmaintained)"
+This field is currently unused on Linux.
+.\" On some systems,
+.\" this is the integral of the text segment memory consumption,
+.\" expressed in kilobyte-seconds.
+.TP
+.IR ru_idrss " (unmaintained)"
+This field is currently unused on Linux.
+.\" On some systems, this is the integral of the data segment memory consumption,
+.\" expressed in kilobyte-seconds.
+.TP
+.IR ru_isrss " (unmaintained)"
+This field is currently unused on Linux.
+.\" On some systems, this is the integral of the stack memory consumption,
+.\" expressed in kilobyte-seconds.
+.TP
+.I ru_minflt
+The number of page faults serviced without any I/O activity; here
+I/O activity is avoided by \*(lqreclaiming\*(rq a page frame from
+the list of pages awaiting reallocation.
+.TP
+.I ru_majflt
+The number of page faults serviced that required I/O activity.
+.TP
+.IR ru_nswap  " (unmaintained)"
+This field is currently unused on Linux.
+.\" On some systems, this is the number of swaps out of physical memory.
+.TP
+.IR ru_inblock " (since Linux 2.6.22)"
+The number of times the filesystem had to perform input.
+.TP
+.IR ru_oublock " (since Linux 2.6.22)"
+The number of times the filesystem had to perform output.
+.TP
+.IR ru_msgsnd " (unmaintained)"
+This field is currently unused on Linux.
+.\" On FreeBSD 6.2, this appears to measure messages sent over sockets
+.\" On some systems,
+.\" this field records the number of messages sent over sockets.
+.TP
+.IR ru_msgrcv " (unmaintained)"
+This field is currently unused on Linux.
+.\" On FreeBSD 6.2, this appears to measure messages received over sockets
+.\" On some systems,
+.\" this field records the number of messages received over sockets.
+.TP
+.IR ru_nsignals " (unmaintained)"
+This field is currently unused on Linux.
+.\" On some systems, this field records the number of signals received.
+.TP
+.IR ru_nvcsw " (since Linux 2.6)"
+The number of times a context switch resulted due to a process
+voluntarily giving up the processor before its time slice was
+completed (usually to await availability of a resource).
+.TP
+.IR ru_nivcsw " (since Linux 2.6)"
+The number of times a context switch resulted due to a higher
+priority process becoming runnable or because the current process
+exceeded its time slice.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I usage
+points outside the accessible address space.
+.TP
+.B EINVAL
+.I who
+is invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getrusage ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.P
+POSIX.1 specifies
+.BR getrusage (),
+but specifies only the fields
+.I ru_utime
+and
+.IR ru_stime .
+.P
+.B RUSAGE_THREAD
+is Linux-specific.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.P
+Before Linux 2.6.9, if the disposition of
+.B SIGCHLD
+is set to
+.B SIG_IGN
+then the resource usages of child processes
+are automatically included in the value returned by
+.BR RUSAGE_CHILDREN ,
+although POSIX.1-2001 explicitly prohibits this.
+This nonconformance is rectified in Linux 2.6.9 and later.
+.\" See the description of getrusage() in XSH.
+.\" A similar statement was also in SUSv2.
+.P
+The structure definition shown at the start of this page
+was taken from 4.3BSD Reno.
+.P
+Ancient systems provided a
+.BR vtimes ()
+function with a similar purpose to
+.BR getrusage ().
+For backward compatibility, glibc (up until Linux 2.32) also provides
+.BR vtimes ().
+All new applications should be written using
+.BR getrusage ().
+(Since Linux 2.33, glibc no longer provides an
+.BR vtimes ()
+implementation.)
+.SH NOTES
+Resource usage metrics are preserved across an
+.BR execve (2).
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR getrlimit (2),
+.BR times (2),
+.BR wait (2),
+.BR wait4 (2),
+.BR clock (3),
+.BR proc_pid_stat (5),
+.BR proc_pid_io (5)
diff --git a/man/man2/getsid.2 b/man/man2/getsid.2
new file mode 100644
index 000000000..c296a92d2
--- /dev/null
+++ b/man/man2/getsid.2
@@ -0,0 +1,75 @@
+.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Thu Oct 31 14:18:40 1996 by Eric S. Raymond <esr@y\thyrsus.com>
+.\" Modified 2001-12-17, aeb
+.TH getsid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getsid \- get session ID
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "pid_t getsid(pid_t" " pid" );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getsid ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+.fi
+.SH DESCRIPTION
+.BR getsid ()
+returns the session ID of the process with process ID
+.IR pid .
+If
+.I pid
+is 0,
+.BR getsid ()
+returns the session ID of the calling process.
+.SH RETURN VALUE
+On success, a session ID is returned.
+On error, \fI(pid_t)\ \-1\fP is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EPERM
+A process with process ID
+.I pid
+exists, but it is not in the same session as the calling process,
+and the implementation considers this an error.
+.TP
+.B ESRCH
+No process with process ID
+.I pid
+was found.
+.SH VERSIONS
+Linux does not return
+.BR EPERM .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+Linux 2.0.
+.\" Linux has this system call since Linux 1.3.44.
+.\" There is libc support since libc 5.2.19.
+.SH NOTES
+See
+.BR credentials (7)
+for a description of sessions and session IDs.
+.SH SEE ALSO
+.BR getpgid (2),
+.BR setsid (2),
+.BR credentials (7)
diff --git a/man/man2/getsockname.2 b/man/man2/getsockname.2
new file mode 100644
index 000000000..27a0b7e61
--- /dev/null
+++ b/man/man2/getsockname.2
@@ -0,0 +1,85 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)getsockname.2	6.4 (Berkeley) 3/10/91
+.\"
+.\" Modified Sat Jul 24 16:30:29 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 00:22:35 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Sun Mar 28 21:26:46 1999 by Andries Brouwer <aeb@cwi.nl>
+.\"
+.TH getsockname 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getsockname \- get socket name
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int getsockname(int " sockfd ", struct sockaddr *restrict " addr ,
+.BI "                socklen_t *restrict " addrlen );
+.fi
+.SH DESCRIPTION
+.BR getsockname ()
+returns the current address to which the socket
+.I sockfd
+is bound, in the buffer pointed to by
+.IR addr .
+The
+.I addrlen
+argument should be initialized to indicate
+the amount of space (in bytes) pointed to by
+.IR addr .
+On return it contains the actual size of the socket address.
+.P
+The returned address is truncated if the buffer provided is too small;
+in this case,
+.I addrlen
+will return a value greater than was supplied to the call.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The argument
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+The
+.I addr
+argument points to memory not in a valid part of the
+process address space.
+.TP
+.B EINVAL
+.I addrlen
+is invalid (e.g., is negative).
+.TP
+.B ENOBUFS
+Insufficient resources were available in the system
+to perform the operation.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD
+(first appeared in 4.2BSD).
+.\" SVr4 documents additional ENOMEM
+.\" and ENOSR error codes.
+.SH SEE ALSO
+.BR bind (2),
+.BR socket (2),
+.BR getifaddrs (3),
+.BR ip (7),
+.BR socket (7),
+.BR unix (7)
diff --git a/man/man2/getsockopt.2 b/man/man2/getsockopt.2
new file mode 100644
index 000000000..d0a24db76
--- /dev/null
+++ b/man/man2/getsockopt.2
@@ -0,0 +1,172 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     $Id: getsockopt.2,v 1.1 1999/05/24 14:57:04 freitag Exp $
+.\"
+.\" Modified Sat Jul 24 16:19:32 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon Apr 22 02:29:06 1996 by Martin Schulze (joey@infodrom.north.de)
+.\" Modified Tue Aug 27 10:52:51 1996 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Thu Jan 23 13:29:34 1997 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Sun Mar 28 21:26:46 1999 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified 1999 by Andi Kleen <ak@muc.de>.
+.\"     Removed most stuff because it is in socket.7 now.
+.\"
+.TH getsockopt 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getsockopt, setsockopt \- get and set options on sockets
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int getsockopt(int " sockfd ", int " level ", int " optname ,
+.BI "               void " optval "[restrict *." optlen ],
+.BI "               socklen_t *restrict " optlen );
+.BI "int setsockopt(int " sockfd ", int " level ", int " optname ,
+.BI "               const void " optval [. optlen ],
+.BI "               socklen_t " optlen );
+.fi
+.SH DESCRIPTION
+.BR getsockopt ()
+and
+.BR setsockopt ()
+manipulate options for the socket referred to by the file descriptor
+.IR sockfd .
+Options may exist at multiple
+protocol levels; they are always present at the uppermost
+socket level.
+.P
+When manipulating socket options, the level at which the
+option resides and the name of the option must be specified.
+To manipulate options at the sockets API level,
+.I level
+is specified as
+.BR SOL_SOCKET .
+To manipulate options at any
+other level the protocol number of the appropriate protocol
+controlling the option is supplied.
+For example,
+to indicate that an option is to be interpreted by the
+.B TCP
+protocol,
+.I level
+should be set to the protocol number of
+.BR TCP ;
+see
+.BR getprotoent (3).
+.P
+The arguments
+.I optval
+and
+.I optlen
+are used to access option values for
+.BR setsockopt ().
+For
+.BR getsockopt ()
+they identify a buffer in which the value for the
+requested option(s) are to be returned.
+For
+.BR getsockopt (),
+.I optlen
+is a value-result argument, initially containing the
+size of the buffer pointed to by
+.IR optval ,
+and modified on return to indicate the actual size of
+the value returned.
+If no option value is to be supplied or returned,
+.I optval
+may be NULL.
+.P
+.I Optname
+and any specified options are passed uninterpreted to the appropriate
+protocol module for interpretation.
+The include file
+.I <sys/socket.h>
+contains definitions for socket level options, described below.
+Options at
+other protocol levels vary in format and name; consult the appropriate
+entries in section 4 of the manual.
+.P
+Most socket-level options utilize an
+.I int
+argument for
+.IR optval .
+For
+.BR setsockopt (),
+the argument should be nonzero to enable a boolean option, or zero if the
+option is to be disabled.
+.P
+For a description of the available socket options see
+.BR socket (7)
+and the appropriate protocol man pages.
+.SH RETURN VALUE
+On success, zero is returned for the standard options.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+Netfilter allows the programmer
+to define custom socket options with associated handlers; for such
+options, the return value on success is the value returned by the handler.
+.SH ERRORS
+.TP
+.B EBADF
+The argument
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+The address pointed to by
+.I optval
+is not in a valid part of the process address space.
+For
+.BR getsockopt (),
+this error may also be returned if
+.I optlen
+is not in a valid part of the process address space.
+.TP
+.B EINVAL
+.I optlen
+invalid in
+.BR setsockopt ().
+In some cases this error can also occur for an invalid value in
+.I optval
+(e.g., for the
+.B IP_ADD_MEMBERSHIP
+option described in
+.BR ip (7)).
+.TP
+.B ENOPROTOOPT
+The option is unknown at the level indicated.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001,
+SVr4, 4.4BSD (first appeared in 4.2BSD).
+.\" SVr4 documents additional ENOMEM and ENOSR error codes, but does
+.\" not document the
+.\" .BR SO_SNDLOWAT ", " SO_RCVLOWAT ", " SO_SNDTIMEO ", " SO_RCVTIMEO
+.\" options
+.SH BUGS
+Several of the socket options should be handled at lower levels of the
+system.
+.SH SEE ALSO
+.BR ioctl (2),
+.BR socket (2),
+.BR getprotoent (3),
+.BR protocols (5),
+.BR ip (7),
+.BR packet (7),
+.BR socket (7),
+.BR tcp (7),
+.BR udp (7),
+.BR unix (7)
diff --git a/man/man2/gettid.2 b/man/man2/gettid.2
new file mode 100644
index 000000000..2a8f932f6
--- /dev/null
+++ b/man/man2/gettid.2
@@ -0,0 +1,74 @@
+.\" Copyright 2003 Abhijit Menon-Sen <ams@wiw.org>
+.\" and Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH gettid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gettid \- get thread identification
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #define _GNU_SOURCE
+.B #include <unistd.h>
+.P
+.B pid_t gettid(void);
+.fi
+.SH DESCRIPTION
+.BR gettid ()
+returns the caller's thread ID (TID).
+In a single-threaded process, the thread ID
+is equal to the process ID (PID, as returned by
+.BR getpid (2)).
+In a multithreaded process, all threads
+have the same PID, but each one has a unique TID.
+For further details, see the discussion of
+.B CLONE_THREAD
+in
+.BR clone (2).
+.SH RETURN VALUE
+On success, returns the thread ID of the calling thread.
+.SH ERRORS
+This call is always successful.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.4.11,
+glibc 2.30.
+.SH NOTES
+The thread ID returned by this call is not the same thing as a
+POSIX thread ID (i.e., the opaque value returned by
+.BR pthread_self (3)).
+.P
+In a new thread group created by a
+.BR clone (2)
+call that does not specify the
+.B CLONE_THREAD
+flag (or, equivalently, a new process created by
+.BR fork (2)),
+the new process is a thread group leader,
+and its thread group ID (the value returned by
+.BR getpid (2))
+is the same as its thread ID (the value returned by
+.BR gettid ()).
+.SH SEE ALSO
+.BR capget (2),
+.BR clone (2),
+.BR fcntl (2),
+.BR fork (2),
+.BR get_robust_list (2),
+.BR getpid (2),
+.\" .BR kcmp (2),
+.BR ioprio_set (2),
+.\" .BR move_pages (2),
+.\" .BR migrate_pages (2),
+.BR perf_event_open (2),
+.\" .BR process_vm_readv (2),
+.\" .BR ptrace (2),
+.BR sched_setaffinity (2),
+.BR sched_setparam (2),
+.BR sched_setscheduler (2),
+.BR tgkill (2),
+.BR timer_create (2)
diff --git a/man/man2/gettimeofday.2 b/man/man2/gettimeofday.2
new file mode 100644
index 000000000..e0231e230
--- /dev/null
+++ b/man/man2/gettimeofday.2
@@ -0,0 +1,296 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt (michael@moria.de)
+.\" Modified 1993-07-23 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1994-08-21 by Michael Chastain (mec@shell.portal.com):
+.\"   Fixed necessary '#include' lines.
+.\" Modified 1995-04-15 by Michael Chastain (mec@shell.portal.com):
+.\"   Added reference to adjtimex.
+.\" Removed some nonsense lines pointed out by Urs Thuermann,
+.\"   (urs@isnogud.escape.de), aeb, 950722.
+.\" Modified 1997-01-14 by Austin Donnelly (and1000@debian.org):
+.\"   Added return values section, and bit on EFAULT
+.\" Added clarification on timezone, aeb, 971210.
+.\" Removed "#include <unistd.h>", aeb, 010316.
+.\" Modified, 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"   Added notes on capability requirement.
+.\"
+.TH gettimeofday 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gettimeofday, settimeofday \- get / set time
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/time.h>
+.P
+.BI "int gettimeofday(struct timeval *restrict " tv ,
+.BI "                 struct timezone *_Nullable restrict " tz );
+.BI "int settimeofday(const struct timeval *" tv ,
+.BI "                 const struct timezone *_Nullable " tz );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR settimeofday ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The functions
+.BR gettimeofday ()
+and
+.BR settimeofday ()
+can get and set the time as well as a timezone.
+.P
+The
+.I tv
+argument is a
+.I struct timeval
+(as specified in
+.IR <sys/time.h> ):
+.P
+.in +4n
+.EX
+struct timeval {
+    time_t      tv_sec;     /* seconds */
+    suseconds_t tv_usec;    /* microseconds */
+};
+.EE
+.in
+.P
+and gives the number of seconds and microseconds since the Epoch (see
+.BR time (2)).
+.P
+The
+.I tz
+argument is a
+.IR "struct timezone" :
+.P
+.in +4n
+.EX
+struct timezone {
+    int tz_minuteswest;     /* minutes west of Greenwich */
+    int tz_dsttime;         /* type of DST correction */
+};
+.EE
+.in
+.P
+If either
+.I tv
+or
+.I tz
+is NULL, the corresponding structure is not set or returned.
+.\" FIXME . The compilation warning looks to be going away in glibc 2.17
+.\" see glibc commit 4b7634a5e03b0da6f8875de9d3f74c1cf6f2a6e8
+(However, compilation warnings will result if
+.I tv
+is NULL.)
+.\" The following is covered under EPERM below:
+.\" .P
+.\" Only the superuser may use
+.\" .BR settimeofday ().
+.P
+The use of the
+.I timezone
+structure is obsolete; the
+.I tz
+argument should normally be specified as NULL.
+(See NOTES below.)
+.P
+Under Linux, there are some peculiar "warp clock" semantics associated
+with the
+.BR settimeofday ()
+system call if on the very first call (after booting)
+that has a non-NULL
+.I tz
+argument, the
+.I tv
+argument is NULL and the
+.I tz_minuteswest
+field is nonzero.
+(The
+.I tz_dsttime
+field should be zero for this case.)
+In such a case it is assumed that the CMOS clock
+is on local time, and that it has to be incremented by this amount
+to get UTC system time.
+No doubt it is a bad idea to use this feature.
+.SH RETURN VALUE
+.BR gettimeofday ()
+and
+.BR settimeofday ()
+return 0 for success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+One of
+.I tv
+or
+.I tz
+pointed outside the accessible address space.
+.TP
+.B EINVAL
+.RB ( settimeofday ()):
+.I timezone
+is invalid.
+.TP
+.B EINVAL
+.RB ( settimeofday ()):
+.I tv.tv_sec
+is negative or
+.I tv.tv_usec
+is outside the range [0, 999,999].
+.TP
+.BR EINVAL " (since Linux 4.3)"
+.\" commit e1d7ba8735551ed79c7a0463a042353574b96da3
+.RB ( settimeofday ()):
+An attempt was made to set the time to a value less than
+the current value of the
+.B CLOCK_MONOTONIC
+clock (see
+.BR clock_gettime (2)).
+.TP
+.B EPERM
+The calling process has insufficient privilege to call
+.BR settimeofday ();
+under Linux the
+.B CAP_SYS_TIME
+capability is required.
+.SH VERSIONS
+.SS C library/kernel differences
+On some architectures, an implementation of
+.BR gettimeofday ()
+is provided in the
+.BR vdso (7).
+.P
+The kernel accepts NULL for both
+.I tv
+and
+.IR tz .
+The timezone argument is ignored by glibc and musl,
+and not passed to/from the kernel.
+Android's bionic passes the timezone argument to/from the kernel,
+but Android does not update the kernel timezone
+based on the device timezone in Settings,
+so the kernel's timezone is typically UTC.
+.SH STANDARDS
+.TP
+.BR gettimeofday ()
+POSIX.1-2008 (obsolete).
+.TP
+.BR settimeofday ()
+None.
+.SH HISTORY
+SVr4, 4.3BSD.
+POSIX.1-2001 describes
+.BR gettimeofday ()
+but not
+.BR settimeofday ().
+POSIX.1-2008 marks
+.BR gettimeofday ()
+as obsolete, recommending the use of
+.BR clock_gettime (2)
+instead.
+.P
+Traditionally, the fields of
+.I struct timeval
+were of type
+.IR long .
+.\"
+.SS The tz_dsttime field
+On a non-Linux kernel, with glibc, the
+.I tz_dsttime
+field of
+.I struct timezone
+will be set to a nonzero value by
+.BR gettimeofday ()
+if the current timezone has ever had or will have a daylight saving
+rule applied.
+In this sense it exactly mirrors the meaning of
+.BR daylight (3)
+for the current zone.
+On Linux, with glibc, the setting of the
+.I tz_dsttime
+field of
+.I struct timezone
+has never been used by
+.BR settimeofday ()
+or
+.BR gettimeofday ().
+.\" it has not
+.\" been and will not be supported by libc or glibc.
+.\" Each and every occurrence of this field in the kernel source
+.\" (other than the declaration) is a bug.
+Thus, the following is purely of historical interest.
+.P
+On old systems, the field
+.I tz_dsttime
+contains a symbolic constant (values are given below)
+that indicates in which part of the year Daylight Saving Time
+is in force.
+(Note: this value is constant throughout the year:
+it does not indicate that DST is in force, it just selects an
+algorithm.)
+The daylight saving time algorithms defined are as follows:
+.P
+.in +4n
+.EX
+\fBDST_NONE\fP     /* not on DST */
+\fBDST_USA\fP      /* USA style DST */
+\fBDST_AUST\fP     /* Australian style DST */
+\fBDST_WET\fP      /* Western European DST */
+\fBDST_MET\fP      /* Middle European DST */
+\fBDST_EET\fP      /* Eastern European DST */
+\fBDST_CAN\fP      /* Canada */
+\fBDST_GB\fP       /* Great Britain and Eire */
+\fBDST_RUM\fP      /* Romania */
+\fBDST_TUR\fP      /* Turkey */
+\fBDST_AUSTALT\fP  /* Australian style with shift in 1986 */
+.EE
+.in
+.P
+Of course it turned out that the period in which
+Daylight Saving Time is in force cannot be given
+by a simple algorithm, one per country; indeed,
+this period is determined by unpredictable political
+decisions.
+So this method of representing timezones
+has been abandoned.
+.SH NOTES
+The time returned by
+.BR gettimeofday ()
+.I is
+affected by discontinuous jumps in the system time
+(e.g., if the system administrator manually changes the system time).
+If you need a monotonically increasing clock, see
+.BR clock_gettime (2).
+.P
+Macros for operating on
+.I timeval
+structures are described in
+.BR timeradd (3).
+.SH SEE ALSO
+.BR date (1),
+.BR adjtimex (2),
+.BR clock_gettime (2),
+.BR time (2),
+.BR ctime (3),
+.BR ftime (3),
+.BR timeradd (3),
+.BR capabilities (7),
+.BR time (7),
+.BR vdso (7),
+.BR hwclock (8)
diff --git a/man/man2/getuid.2 b/man/man2/getuid.2
new file mode 100644
index 000000000..700571729
--- /dev/null
+++ b/man/man2/getuid.2
@@ -0,0 +1,80 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Historical remark, aeb, 2004-06-05
+.TH getuid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getuid, geteuid \- get user identity
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B uid_t getuid(void);
+.B uid_t geteuid(void);
+.fi
+.SH DESCRIPTION
+.BR getuid ()
+returns the real user ID of the calling process.
+.P
+.BR geteuid ()
+returns the effective user ID of the calling process.
+.SH ERRORS
+These functions are always successful
+and never modify
+.\" https://www.austingroupbugs.net/view.php?id=511
+.\" 0000511: getuid and friends should not modify errno
+.IR errno .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.P
+In UNIX\ V6 the
+.BR getuid ()
+call returned
+.IR "(euid << 8) + uid" .
+UNIX\ V7 introduced separate calls
+.BR getuid ()
+and
+.BR geteuid ().
+.P
+The original Linux
+.BR getuid ()
+and
+.BR geteuid ()
+system calls supported only 16-bit user IDs.
+Subsequently, Linux 2.4 added
+.BR getuid32 ()
+and
+.BR geteuid32 (),
+supporting 32-bit IDs.
+The glibc
+.BR getuid ()
+and
+.BR geteuid ()
+wrapper functions transparently deal with the variations across kernel versions.
+.P
+On Alpha, instead of a pair of
+.BR getuid ()
+and
+.BR geteuid ()
+system calls, a single
+.BR getxuid ()
+system call is provided, which returns a pair of real and effective UIDs.
+The glibc
+.BR getuid ()
+and
+.BR geteuid ()
+wrapper functions transparently deal with this.
+See
+.BR syscall (2)
+for details regarding register mapping.
+.SH SEE ALSO
+.BR getresuid (2),
+.BR setreuid (2),
+.BR setuid (2),
+.BR credentials (7)
diff --git a/man/man2/getuid32.2 b/man/man2/getuid32.2
new file mode 100644
index 000000000..165cfe1d0
--- /dev/null
+++ b/man/man2/getuid32.2
@@ -0,0 +1 @@
+.so man2/getuid.2
diff --git a/man/man2/getunwind.2 b/man/man2/getunwind.2
new file mode 100644
index 000000000..4abecc108
--- /dev/null
+++ b/man/man2/getunwind.2
@@ -0,0 +1,87 @@
+.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+.\" Written by Marcela Maslanova <mmaslano@redhat.com>
+.\" and Copyright 2013, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getunwind 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getunwind \- copy the unwind data to caller's buffer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <linux/unwind.h>
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "[[deprecated]] long syscall(SYS_getunwind, void " buf [. buf_size ],
+.BI "                            size_t " buf_size );
+.fi
+.SH DESCRIPTION
+.I Note: this system call is obsolete.
+.P
+The
+IA-64-specific
+.BR getunwind ()
+system call copies the kernel's call frame
+unwind data into the buffer pointed to by
+.I buf
+and returns the size of the unwind data;
+this data describes the gate page (kernel code that
+is mapped into user space).
+.P
+The size of the buffer
+.I buf
+is specified in
+.IR buf_size .
+The data is copied only if
+.I buf_size
+is greater than or equal to the size of the unwind data and
+.I buf
+is not NULL;
+otherwise, no data is copied, and the call succeeds,
+returning the size that would be needed to store the unwind data.
+.P
+The first part of the unwind data contains an unwind table.
+The rest contains the associated unwind information, in no particular order.
+The unwind table contains entries of the following form:
+.P
+.in +4n
+.EX
+u64 start;      (64\-bit address of start of function)
+u64 end;        (64\-bit address of end of function)
+u64 info;       (BUF\-relative offset to unwind info)
+.EE
+.in
+.P
+An entry whose
+.I start
+value is zero indicates the end of the table.
+For more information about the format, see the
+.I IA-64 Software Conventions and Runtime Architecture
+manual.
+.SH RETURN VALUE
+On success,
+.BR getunwind ()
+returns the size of the unwind data.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR getunwind ()
+fails with the error
+.B EFAULT
+if the unwind info can't be stored in the space specified by
+.IR buf .
+.SH STANDARDS
+Linux on IA-64.
+.SH HISTORY
+Linux 2.4.
+.P
+This system call has been deprecated.
+The modern way to obtain the kernel's unwind data is via the
+.BR vdso (7).
+.SH SEE ALSO
+.BR getauxval (3)
diff --git a/man/man2/getxattr.2 b/man/man2/getxattr.2
new file mode 100644
index 000000000..f0b872f8c
--- /dev/null
+++ b/man/man2/getxattr.2
@@ -0,0 +1,143 @@
+.\" Copyright (C) Andreas Gruenbacher, February 2001
+.\" Copyright (C) Silicon Graphics Inc, September 2001
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH getxattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getxattr, lgetxattr, fgetxattr \- retrieve an extended attribute value
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/xattr.h>
+.P
+.BI "ssize_t getxattr(const char *" path ", const char *" name ,
+.BI "                 void " value [. size "], size_t " size );
+.BI "ssize_t lgetxattr(const char *" path ", const char *" name ,
+.BI "                 void " value [. size "], size_t " size );
+.BI "ssize_t fgetxattr(int " fd ", const char *" name ,
+.BI "                 void " value [. size "], size_t " size );
+.fi
+.SH DESCRIPTION
+Extended attributes are
+.IR name : value
+pairs associated with inodes (files, directories, symbolic links, etc.).
+They are extensions to the normal attributes which are associated
+with all inodes in the system (i.e., the
+.BR stat (2)
+data).
+A complete overview of extended attributes concepts can be found in
+.BR xattr (7).
+.P
+.BR getxattr ()
+retrieves the value of the extended attribute identified by
+.I name
+and associated with the given
+.I path
+in the filesystem.
+The attribute value is placed in the buffer pointed to by
+.IR value ;
+.I size
+specifies the size of that buffer.
+The return value of the call is the number of bytes placed in
+.IR value .
+.P
+.BR lgetxattr ()
+is identical to
+.BR getxattr (),
+except in the case of a symbolic link, where the link itself is
+interrogated, not the file that it refers to.
+.P
+.BR fgetxattr ()
+is identical to
+.BR getxattr (),
+only the open file referred to by
+.I fd
+(as returned by
+.BR open (2))
+is interrogated in place of
+.IR path .
+.P
+An extended attribute
+.I name
+is a null-terminated string.
+The name includes a namespace prefix; there may be several, disjoint
+namespaces associated with an individual inode.
+The value of an extended attribute is a chunk of arbitrary textual or
+binary data that was assigned using
+.BR setxattr (2).
+.P
+If
+.I size
+is specified as zero, these calls return the current size of the
+named extended attribute (and leave
+.I value
+unchanged).
+This can be used to determine the size of the buffer that
+should be supplied in a subsequent call.
+(But, bear in mind that there is a possibility that the
+attribute value may change between the two calls,
+so that it is still necessary to check the return status
+from the second call.)
+.SH RETURN VALUE
+On success, these calls return a nonnegative value which is
+the size (in bytes) of the extended attribute value.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B E2BIG
+The size of the attribute value is larger than the maximum size allowed; the
+attribute cannot be retrieved.
+This can happen on filesystems that support
+very large attribute values such as NFSv4, for example.
+.TP
+.B ENODATA
+The named attribute does not exist, or the process has no access to
+this attribute.
+.\" .RB ( ENOATTR
+.\" is defined to be a synonym for
+.\" .BR ENODATA
+.\" in
+.\" .IR <attr/attributes.h> .)
+.TP
+.B ENOTSUP
+Extended attributes are not supported by the filesystem, or are disabled.
+.TP
+.B ERANGE
+The
+.I size
+of the
+.I value
+buffer is too small to hold the result.
+.P
+In addition, the errors documented in
+.BR stat (2)
+can also occur.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.4,
+glibc 2.3.
+.\" .SH AUTHORS
+.\" Andreas Gruenbacher,
+.\" .RI < a.gruenbacher@computer.org >
+.\" and the SGI XFS development team,
+.\" .RI < linux-xfs@oss.sgi.com >.
+.\" Please send any bug reports or comments to these addresses.
+.SH EXAMPLES
+See
+.BR listxattr (2).
+.SH SEE ALSO
+.BR getfattr (1),
+.BR setfattr (1),
+.BR listxattr (2),
+.BR open (2),
+.BR removexattr (2),
+.BR setxattr (2),
+.BR stat (2),
+.BR symlink (7),
+.BR xattr (7)
diff --git a/man/man2/gtty.2 b/man/man2/gtty.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/gtty.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/idle.2 b/man/man2/idle.2
new file mode 100644
index 000000000..a63c17ce1
--- /dev/null
+++ b/man/man2/idle.2
@@ -0,0 +1,44 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\" Portions extracted from linux/mm/swap.c:
+.\"                Copyright (C) 1991, 1992  Linus Torvalds
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 21 Aug 1994 by Michael Chastain <mec@shell.portal.com>:
+.\"   Added text about calling restriction (new in Linux 1.1.20 I believe).
+.\"   N.B. calling "idle" from user process used to hang process!
+.\" Modified Thu Oct 31 14:41:15 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" "
+.TH idle 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+idle \- make process 0 idle
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B [[deprecated]] int idle(void);
+.fi
+.SH DESCRIPTION
+.BR idle ()
+is an internal system call used during bootstrap.
+It marks the process's pages as swappable, lowers its priority,
+and enters the main scheduling loop.
+.BR idle ()
+never returns.
+.P
+Only process 0 may call
+.BR idle ().
+Any user process, even a process with superuser permission,
+will receive
+.BR EPERM .
+.SH RETURN VALUE
+.BR idle ()
+never returns for process 0, and always returns \-1 for a user process.
+.SH ERRORS
+.TP
+.B EPERM
+Always, for a user process.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Removed in Linux 2.3.13.
diff --git a/man/man2/inb.2 b/man/man2/inb.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/inb.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/inb_p.2 b/man/man2/inb_p.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/inb_p.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/init_module.2 b/man/man2/init_module.2
new file mode 100644
index 000000000..5055f2546
--- /dev/null
+++ b/man/man2/init_module.2
@@ -0,0 +1,393 @@
+.\" Copyright (C) 2012 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" A few fragments remain from a version
+.\" Copyright (C) 1996 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH init_module 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+init_module, finit_module \- load a kernel module
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/module.h>" "    /* Definition of " MODULE_* " constants */"
+.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_init_module, void " module_image [. len "], \
+unsigned long " len ,
+.BI "            const char *" param_values );
+.BI "int syscall(SYS_finit_module, int " fd ,
+.BI "            const char *" param_values ", int " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR init_module ()
+loads an ELF image into kernel space,
+performs any necessary symbol relocations,
+initializes module parameters to values provided by the caller,
+and then runs the module's
+.I init
+function.
+This system call requires privilege.
+.P
+The
+.I module_image
+argument points to a buffer containing the binary image
+to be loaded;
+.I len
+specifies the size of that buffer.
+The module image should be a valid ELF image, built for the running kernel.
+.P
+The
+.I param_values
+argument is a string containing space-delimited specifications of the
+values for module parameters (defined inside the module using
+.BR module_param ()
+and
+.BR module_param_array ()).
+The kernel parses this string and initializes the specified
+parameters.
+Each of the parameter specifications has the form:
+.P
+.RI "        " name [\c
+.BI = value\c
+.RB [ ,\c
+.IR value ...]]
+.P
+The parameter
+.I name
+is one of those defined within the module using
+.IR module_param ()
+(see the Linux kernel source file
+.IR include/linux/moduleparam.h ).
+The parameter
+.I value
+is optional in the case of
+.I bool
+and
+.I invbool
+parameters.
+Values for array parameters are specified as a comma-separated list.
+.SS finit_module()
+The
+.BR finit_module ()
+.\" commit 34e1169d996ab148490c01b65b4ee371cf8ffba2
+.\" https://lwn.net/Articles/519010/
+system call is like
+.BR init_module (),
+but reads the module to be loaded from the file descriptor
+.IR fd .
+It is useful when the authenticity of a kernel module
+can be determined from its location in the filesystem;
+in cases where that is possible,
+the overhead of using cryptographically signed modules to
+determine the authenticity of a module can be avoided.
+The
+.I param_values
+argument is as for
+.BR init_module ().
+.P
+The
+.I flags
+argument modifies the operation of
+.BR finit_module ().
+It is a bit mask value created by ORing
+together zero or more of the following flags:
+.\" commit 2f3238aebedb243804f58d62d57244edec4149b2
+.TP
+.B MODULE_INIT_IGNORE_MODVERSIONS
+Ignore symbol version hashes.
+.TP
+.B MODULE_INIT_IGNORE_VERMAGIC
+Ignore kernel version magic.
+.TP
+.BR MODULE_INIT_COMPRESSED_FILE " (since Linux 5.17)"
+.\" commit b1ae6dc41eaaa98bb75671e0f3665bfda248c3e7
+Use in-kernel module decompression.
+.P
+There are some safety checks built into a module to ensure that
+it matches the kernel against which it is loaded.
+.\" http://www.tldp.org/HOWTO/Module-HOWTO/basekerncompat.html
+.\" is dated, but informative
+These checks are recorded when the module is built and
+verified when the module is loaded.
+First, the module records a "vermagic" string containing
+the kernel version number and prominent features (such as the CPU type).
+Second, if the module was built with the
+.B CONFIG_MODVERSIONS
+configuration option enabled,
+a version hash is recorded for each symbol the module uses.
+This hash is based on the types of the arguments and return value
+for the function named by the symbol.
+In this case, the kernel version number within the
+"vermagic" string is ignored,
+as the symbol version hashes are assumed to be sufficiently reliable.
+.P
+Using the
+.B MODULE_INIT_IGNORE_VERMAGIC
+flag indicates that the "vermagic" string is to be ignored, and the
+.B MODULE_INIT_IGNORE_MODVERSIONS
+flag indicates that the symbol version hashes are to be ignored.
+If the kernel is built to permit forced loading (i.e., configured with
+.BR CONFIG_MODULE_FORCE_LOAD ),
+then loading continues, otherwise it fails with the error
+.B ENOEXEC
+as expected for malformed modules.
+.P
+If the kernel was build with
+.BR CONFIG_MODULE_DECOMPRESS ,
+the in-kernel decompression feature can be used.
+User-space code can check if the kernel supports decompression
+by reading the
+.I /sys/module/compression
+attribute.
+If the kernel supports decompression,
+the compressed file can directly be passed to
+.BR finit_module ()
+using the
+.B MODULE_INIT_COMPRESSED_FILE
+flag.
+The in-kernel module decompressor supports the following compression algorithms:
+.P
+.RS 4
+.PD 0
+.IP \[bu] 3
+.I gzip
+(since Linux 5.17)
+.IP \[bu]
+.I xz
+(since Linux 5.17)
+.IP \[bu]
+.I zstd
+.\" commit 169a58ad824d896b9e291a27193342616e651b82
+(since Linux 6.2)
+.PD
+.RE
+.P
+The kernel only implements a single decompression method.
+This is selected during module generation accordingly to the compression method
+chosen in the kernel configuration.
+.SH RETURN VALUE
+On success, these system calls return 0.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.BR EBADMSG " (since Linux 3.7)"
+Module signature is misformatted.
+.TP
+.B EBUSY
+Timeout while trying to resolve a symbol reference by this module.
+.TP
+.B EFAULT
+An address argument referred to a location that
+is outside the process's accessible address space.
+.TP
+.BR ENOKEY " (since Linux 3.7)"
+.\" commit 48ba2462ace6072741fd8d0058207d630ce93bf1
+.\" commit 1d0059f3a468825b5fc5405c636a2f6e02707ffa
+.\" commit 106a4ee258d14818467829bf0e12aeae14c16cd7
+Module signature is invalid or
+the kernel does not have a key for this module.
+This error is returned only if the kernel was configured with
+.BR CONFIG_MODULE_SIG_FORCE ;
+if the kernel was not configured with this option,
+then an invalid or unsigned module simply taints the kernel.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B EPERM
+The caller was not privileged
+(did not have the
+.B CAP_SYS_MODULE
+capability),
+or module loading is disabled
+(see
+.I /proc/sys/kernel/modules_disabled
+in
+.BR proc (5)).
+.P
+The following errors may additionally occur for
+.BR init_module ():
+.TP
+.B EEXIST
+A module with this name is already loaded.
+.TP
+.B EINVAL
+.I param_values
+is invalid, or some part of the ELF image in
+.I module_image
+contains inconsistencies.
+.\" .TP
+.\" .BR EINVAL " (Linux 2.4 and earlier)"
+.\" Some
+.\" .I image
+.\" slot is filled in incorrectly,
+.\" .I image\->name
+.\" does not correspond to the original module name, some
+.\" .I image\->deps
+.\" entry does not correspond to a loaded module,
+.\" or some other similar inconsistency.
+.TP
+.B ENOEXEC
+The binary image supplied in
+.I module_image
+is not an ELF image,
+or is an ELF image that is invalid or for a different architecture.
+.P
+The following errors may additionally occur for
+.BR finit_module ():
+.TP
+.B EBADF
+The file referred to by
+.I fd
+is not opened for reading.
+.TP
+.B EFBIG
+The file referred to by
+.I fd
+is too large.
+.TP
+.B EINVAL
+.I flags
+is invalid.
+.TP
+.B EINVAL
+The decompressor sanity checks failed,
+while loading a compressed module with flag
+.B MODULE_INIT_COMPRESSED_FILE
+set.
+.TP
+.B ENOEXEC
+.I fd
+does not refer to an open file.
+.TP
+.BR EOPNOTSUPP " (since Linux 5.17)"
+The flag
+.B MODULE_INIT_COMPRESSED_FILE
+is set to load a compressed module,
+and the kernel was built without
+.BR CONFIG_MODULE_DECOMPRESS .
+.TP
+.BR ETXTBSY " (since Linux 4.7)"
+.\" commit 39d637af5aa7577f655c58b9e55587566c63a0af
+The file referred to by
+.I fd
+is opened for read-write.
+.P
+In addition to the above errors, if the module's
+.I init
+function is executed and returns an error, then
+.BR init_module ()
+or
+.BR finit_module ()
+fails and
+.I errno
+is set to the value returned by the
+.I init
+function.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR finit_module ()
+Linux 3.8.
+.P
+The
+.BR init_module ()
+system call is not supported by glibc.
+No declaration is provided in glibc headers, but, through a quirk of history,
+glibc versions before glibc 2.23 did export an ABI for this system call.
+Therefore, in order to employ this system call,
+it is (before glibc 2.23) sufficient to
+manually declare the interface in your code;
+alternatively, you can invoke the system call using
+.BR syscall (2).
+.SS Linux 2.4 and earlier
+In Linux 2.4 and earlier, the
+.BR init_module ()
+system call was rather different:
+.P
+.B "    #include <linux/module.h>"
+.P
+.BI "    int init_module(const char *" name ", struct module *" image );
+.P
+(User-space applications can detect which version of
+.BR init_module ()
+is available by calling
+.BR query_module ();
+the latter call fails with the error
+.B ENOSYS
+on Linux 2.6 and later.)
+.P
+The older version of the system call
+loads the relocated module image pointed to by
+.I image
+into kernel space and runs the module's
+.I init
+function.
+The caller is responsible for providing the relocated image (since
+Linux 2.6, the
+.BR init_module ()
+system call does the relocation).
+.P
+The module image begins with a module structure and is followed by
+code and data as appropriate.
+Since Linux 2.2, the module structure is defined as follows:
+.P
+.in +4n
+.EX
+struct module {
+    unsigned long         size_of_struct;
+    struct module        *next;
+    const char           *name;
+    unsigned long         size;
+    long                  usecount;
+    unsigned long         flags;
+    unsigned int          nsyms;
+    unsigned int          ndeps;
+    struct module_symbol *syms;
+    struct module_ref    *deps;
+    struct module_ref    *refs;
+    int                 (*init)(void);
+    void                (*cleanup)(void);
+    const struct exception_table_entry *ex_table_start;
+    const struct exception_table_entry *ex_table_end;
+#ifdef __alpha__
+    unsigned long gp;
+#endif
+};
+.EE
+.in
+.P
+All of the pointer fields, with the exception of
+.I next
+and
+.IR refs ,
+are expected to point within the module body and be
+initialized as appropriate for kernel space, that is, relocated with
+the rest of the module.
+.SH NOTES
+Information about currently loaded modules can be found in
+.I /proc/modules
+and in the file trees under the per-module subdirectories under
+.IR /sys/module .
+.P
+See the Linux kernel source file
+.I include/linux/module.h
+for some useful background information.
+.SH SEE ALSO
+.BR create_module (2),
+.BR delete_module (2),
+.BR query_module (2),
+.BR lsmod (8),
+.BR modprobe (8)
diff --git a/man/man2/inl.2 b/man/man2/inl.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/inl.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/inl_p.2 b/man/man2/inl_p.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/inl_p.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/inotify_add_watch.2 b/man/man2/inotify_add_watch.2
new file mode 100644
index 000000000..61d3987ec
--- /dev/null
+++ b/man/man2/inotify_add_watch.2
@@ -0,0 +1,135 @@
+.\" Copyright (C) 2005 Robert Love
+.\" and Copyright, 2006 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2005-07-19 Robert Love <rlove@rlove.org> - initial version
+.\" 2006-02-07 mtk, various changes
+.\"
+.TH inotify_add_watch 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inotify_add_watch \- add a watch to an initialized inotify instance
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/inotify.h>
+.P
+.BI "int inotify_add_watch(int " fd ", const char *" pathname ", uint32_t " mask );
+.fi
+.SH DESCRIPTION
+.BR inotify_add_watch ()
+adds a new watch, or modifies an existing watch,
+for the file whose location is specified in
+.IR pathname ;
+the caller must have read permission for this file.
+The
+.I fd
+argument is a file descriptor referring to the
+inotify instance whose watch list is to be modified.
+The events to be monitored for
+.I pathname
+are specified in the
+.I mask
+bit-mask argument.
+See
+.BR inotify (7)
+for a description of the bits that can be set in
+.IR mask .
+.P
+A successful call to
+.BR inotify_add_watch ()
+returns a unique watch descriptor for this inotify instance,
+for the filesystem object (inode) that corresponds to
+.IR pathname .
+If the filesystem object
+was not previously being watched by this inotify instance,
+then the watch descriptor is newly allocated.
+If the filesystem object was already being watched
+(perhaps via a different link to the same object), then the descriptor
+for the existing watch is returned.
+.P
+The watch descriptor is returned by later
+.BR read (2)s
+from the inotify file descriptor.
+These reads fetch
+.I inotify_event
+structures (see
+.BR inotify (7))
+indicating filesystem events;
+the watch descriptor inside this structure identifies
+the object for which the event occurred.
+.SH RETURN VALUE
+On success,
+.BR inotify_add_watch ()
+returns a watch descriptor (a nonnegative integer).
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Read access to the given file is not permitted.
+.TP
+.B EBADF
+The given file descriptor is not valid.
+.TP
+.B EEXIST
+.I mask
+contains
+.B IN_MASK_CREATE
+and
+.I pathname
+refers to a file already being watched by the same
+.IR fd .
+.TP
+.B EFAULT
+.I pathname
+points outside of the process's accessible address space.
+.TP
+.B EINVAL
+The given event mask contains no valid events; or
+.I mask
+contains both
+.B IN_MASK_ADD
+and
+.BR IN_MASK_CREATE ;
+or
+.I fd
+is not an inotify file descriptor.
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+A directory component in
+.I pathname
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSPC
+The user limit on the total number of inotify watches was reached or the
+kernel failed to allocate a needed resource.
+.TP
+.B ENOTDIR
+.I mask
+contains
+.B IN_ONLYDIR
+and
+.I pathname
+is not a directory.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.13.
+.SH EXAMPLES
+See
+.BR inotify (7).
+.SH SEE ALSO
+.BR inotify_init (2),
+.BR inotify_rm_watch (2),
+.BR inotify (7)
diff --git a/man/man2/inotify_init.2 b/man/man2/inotify_init.2
new file mode 100644
index 000000000..c5072ef70
--- /dev/null
+++ b/man/man2/inotify_init.2
@@ -0,0 +1,97 @@
+.\" Copyright (C) 2005 Robert Love
+.\" and Copyright (C) 2008, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2005-07-19 Robert Love <rlove@rlove.org> - initial version
+.\" 2006-02-07 mtk, minor changes
+.\" 2008-10-10 mtk: add description of inotify_init1()
+.\"
+.TH inotify_init 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inotify_init, inotify_init1 \- initialize an inotify instance
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/inotify.h>
+.P
+.B "int inotify_init(void);"
+.BI "int inotify_init1(int " flags );
+.fi
+.SH DESCRIPTION
+For an overview of the inotify API, see
+.BR inotify (7).
+.P
+.BR inotify_init ()
+initializes a new inotify instance and returns a file descriptor associated
+with a new inotify event queue.
+.P
+If
+.I flags
+is 0, then
+.BR inotify_init1 ()
+is the same as
+.BR inotify_init ().
+The following values can be bitwise ORed in
+.I flags
+to obtain different behavior:
+.TP
+.B IN_NONBLOCK
+Set the
+.B O_NONBLOCK
+file status flag on the open file description (see
+.BR open (2))
+referred to by the new file descriptor.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
+.TP
+.B IN_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.SH RETURN VALUE
+On success, these system calls return a new file descriptor.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.RB ( inotify_init1 ())
+An invalid value was specified in
+.IR flags .
+.TP
+.B EMFILE
+The user limit on the total number of inotify instances has been reached.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+Insufficient kernel memory is available.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR inotify_init ()
+Linux 2.6.13,
+glibc 2.4.
+.TP
+.BR inotify_init1 ()
+Linux 2.6.27,
+glibc 2.9.
+.SH SEE ALSO
+.BR inotify_add_watch (2),
+.BR inotify_rm_watch (2),
+.BR inotify (7)
diff --git a/man/man2/inotify_init1.2 b/man/man2/inotify_init1.2
new file mode 100644
index 000000000..62c5b44e6
--- /dev/null
+++ b/man/man2/inotify_init1.2
@@ -0,0 +1 @@
+.so man2/inotify_init.2
diff --git a/man/man2/inotify_rm_watch.2 b/man/man2/inotify_rm_watch.2
new file mode 100644
index 000000000..2fde52c61
--- /dev/null
+++ b/man/man2/inotify_rm_watch.2
@@ -0,0 +1,60 @@
+.\" Copyright (C) 2005 Robert Love
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2005-07-19 Robert Love <rlove@rlove.org> - initial version
+.\" 2006-02-07 mtk, minor changes
+.\"
+.TH inotify_rm_watch 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inotify_rm_watch \- remove an existing watch from an inotify instance
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/inotify.h>
+.P
+.BI "int inotify_rm_watch(int " fd ", int " wd );
+.\" Before glibc 2.10, the second argument was types as uint32_t.
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=7040
+.fi
+.SH DESCRIPTION
+.BR inotify_rm_watch ()
+removes the watch associated with the watch descriptor
+.I wd
+from the inotify instance associated with the file descriptor
+.IR fd .
+.P
+Removing a watch causes an
+.B IN_IGNORED
+event to be generated for this watch descriptor.
+(See
+.BR inotify (7).)
+.SH RETURN VALUE
+On success,
+.BR inotify_rm_watch ()
+returns zero.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+The watch descriptor
+.I wd
+is not valid; or
+.I fd
+is not an inotify file descriptor.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.13.
+.SH SEE ALSO
+.BR inotify_add_watch (2),
+.BR inotify_init (2),
+.BR inotify (7)
diff --git a/man/man2/insb.2 b/man/man2/insb.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/insb.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/insl.2 b/man/man2/insl.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/insl.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/insw.2 b/man/man2/insw.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/insw.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/intro.2 b/man/man2/intro.2
new file mode 100644
index 000000000..3986bb0a1
--- /dev/null
+++ b/man/man2/intro.2
@@ -0,0 +1,115 @@
+.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2007-10-23 mtk: moved the _syscallN specific material to the
+.\"     new _syscall(2) page, and substantially enhanced and rewrote
+.\"     the remaining material on this page.
+.\"
+.TH intro 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to system calls
+.SH DESCRIPTION
+Section 2 of the manual describes the Linux system calls.
+A system call is an entry point into the Linux kernel.
+Usually, system calls are not invoked directly:
+instead, most system calls have corresponding C library
+wrapper functions which perform the steps required
+(e.g., trapping to kernel mode) in order to invoke
+the system call.
+Thus, making a system call looks the same as invoking a normal
+library function.
+.P
+In many cases, the C library wrapper function does nothing more than:
+.IP \[bu] 3
+copying arguments and the unique system call number to the
+registers where the kernel expects them;
+.IP \[bu]
+trapping to kernel mode,
+at which point the kernel does the real work of the system call;
+.IP \[bu]
+setting
+.I errno
+if the system call returns an error number when the kernel returns the
+CPU to user mode.
+.P
+However, in a few cases, a wrapper function may do rather more than this,
+for example, performing some preprocessing
+of the arguments before trapping to kernel mode,
+or postprocessing of values returned by the system call.
+Where this is the case, the manual pages in Section 2 generally
+try to note the details of both the (usually GNU) C library API
+interface and the raw system call.
+Most commonly, the main DESCRIPTION will focus on the C library interface,
+and differences for the system call are covered in the NOTES section.
+.P
+For a list of the Linux system calls, see
+.BR syscalls (2).
+.SH RETURN VALUE
+On error, most system calls return a negative error number
+(i.e., the negated value of one of the constants described in
+.BR errno (3)).
+The C library wrapper hides this detail from the caller: when a
+system call returns a negative value, the wrapper copies the
+absolute value into the
+.I errno
+variable, and returns \-1 as the return value of the wrapper.
+.P
+The value returned by a successful system call depends on the call.
+Many system calls return 0 on success, but some can return nonzero
+values from a successful call.
+The details are described in the individual manual pages.
+.P
+In some cases,
+the programmer must define a feature test macro in order to obtain
+the declaration of a system call from the header file specified
+in the man page SYNOPSIS section.
+(Where required, these feature test macros must be defined before including
+.I any
+header files.)
+In such cases, the required macro is described in the man page.
+For further information on feature test macros, see
+.BR feature_test_macros (7).
+.SH STANDARDS
+Certain terms and abbreviations are used to indicate UNIX variants
+and standards to which calls in this section conform.
+See
+.BR standards (7).
+.SH NOTES
+.SS Calling directly
+In most cases, it is unnecessary to invoke a system call directly,
+but there are times when the Standard C library does not implement
+a nice wrapper function for you.
+In this case, the programmer must manually invoke the system call using
+.BR syscall (2).
+Historically, this was also possible using one of the _syscall macros
+described in
+.BR _syscall (2).
+.SS Authors and copyright conditions
+Look at the header of the manual page source for the author(s) and copyright
+conditions.
+Note that these can be different from page to page!
+.SH SEE ALSO
+.ad l
+.nh
+.BR _syscall (2),
+.BR syscall (2),
+.BR syscalls (2),
+.BR errno (3),
+.BR intro (3),
+.BR capabilities (7),
+.BR credentials (7),
+.BR feature_test_macros (7),
+.BR mq_overview (7),
+.BR path_resolution (7),
+.BR pipe (7),
+.BR pty (7),
+.BR sem_overview (7),
+.BR shm_overview (7),
+.BR signal (7),
+.BR socket (7),
+.BR standards (7),
+.BR symlink (7),
+.BR system_data_types (7),
+.BR sysvipc (7),
+.BR time (7)
diff --git a/man/man2/inw.2 b/man/man2/inw.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/inw.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/inw_p.2 b/man/man2/inw_p.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/inw_p.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/io_cancel.2 b/man/man2/io_cancel.2
new file mode 100644
index 000000000..3820a916b
--- /dev/null
+++ b/man/man2/io_cancel.2
@@ -0,0 +1,106 @@
+.\" Copyright (C) 2003 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH io_cancel 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+io_cancel \- cancel an outstanding asynchronous I/O operation
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.P
+Alternatively, Asynchronous I/O library
+.RI ( libaio ", " \-laio );
+see VERSIONS.
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/aio_abi.h>" "    /* Definition of needed types */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_io_cancel, aio_context_t " ctx_id ", struct iocb *" iocb ,
+.BI "            struct io_event *" result );
+.fi
+.SH DESCRIPTION
+.IR Note :
+this page describes the raw Linux system call interface.
+The wrapper function provided by
+.I libaio
+uses a different type for the
+.I ctx_id
+argument.
+See VERSIONS.
+.P
+The
+.BR io_cancel ()
+system call
+attempts to cancel an asynchronous I/O operation previously submitted with
+.BR io_submit (2).
+The
+.I iocb
+argument describes the operation to be canceled and the
+.I ctx_id
+argument is the AIO context to which the operation was submitted.
+If the operation is successfully canceled, the event will be copied into
+the memory pointed to by
+.I result
+without being placed into the
+completion queue.
+.SH RETURN VALUE
+On success,
+.BR io_cancel ()
+returns 0.
+For the failure return, see VERSIONS.
+.SH ERRORS
+.TP
+.B EAGAIN
+The \fIiocb\fP specified was not canceled.
+.TP
+.B EFAULT
+One of the data structures points to invalid data.
+.TP
+.B EINVAL
+The AIO context specified by \fIctx_id\fP is invalid.
+.TP
+.B ENOSYS
+.BR io_cancel ()
+is not implemented on this architecture.
+.SH VERSIONS
+You probably want to use the
+.BR io_cancel ()
+wrapper function provided by
+.\" http://git.fedorahosted.org/git/?p=libaio.git
+.IR libaio .
+.P
+Note that the
+.I libaio
+wrapper function uses a different type
+.RI ( io_context_t )
+.\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
+.\" the system call.
+for the
+.I ctx_id
+argument.
+Note also that the
+.I libaio
+wrapper does not follow the usual C library conventions for indicating errors:
+on error it returns a negated error number
+(the negative of one of the values listed in ERRORS).
+If the system call is invoked via
+.BR syscall (2),
+then the return value follows the usual conventions for
+indicating an error: \-1, with
+.I errno
+set to a (positive) value that indicates the error.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.
+.SH SEE ALSO
+.BR io_destroy (2),
+.BR io_getevents (2),
+.BR io_setup (2),
+.BR io_submit (2),
+.BR aio (7)
+.\" .SH AUTHOR
+.\" Kent Yoder.
diff --git a/man/man2/io_destroy.2 b/man/man2/io_destroy.2
new file mode 100644
index 000000000..451cf82ff
--- /dev/null
+++ b/man/man2/io_destroy.2
@@ -0,0 +1,97 @@
+.\" Copyright (C) 2003 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH io_destroy 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+io_destroy \- destroy an asynchronous I/O context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/aio_abi.h>" "    /* Definition of " aio_context_t " */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_io_destroy, aio_context_t " ctx_id );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR io_destroy (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.IR Note :
+this page describes the raw Linux system call interface.
+The wrapper function provided by
+.I libaio
+uses a different type for the
+.I ctx_id
+argument.
+See VERSIONS.
+.P
+The
+.BR io_destroy ()
+system call
+will attempt to cancel all outstanding asynchronous I/O operations against
+.IR ctx_id ,
+will block on the completion of all operations
+that could not be canceled, and will destroy the
+.IR ctx_id .
+.SH RETURN VALUE
+On success,
+.BR io_destroy ()
+returns 0.
+For the failure return, see VERSIONS.
+.SH ERRORS
+.TP
+.B EFAULT
+The context pointed to is invalid.
+.TP
+.B EINVAL
+The AIO context specified by \fIctx_id\fP is invalid.
+.TP
+.B ENOSYS
+.BR io_destroy ()
+is not implemented on this architecture.
+.SH VERSIONS
+You probably want to use the
+.BR io_destroy ()
+wrapper function provided by
+.\" http://git.fedorahosted.org/git/?p=libaio.git
+.IR libaio .
+.P
+Note that the
+.I libaio
+wrapper function uses a different type
+.RI ( io_context_t )
+.\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
+.\" the system call.
+for the
+.I ctx_id
+argument.
+Note also that the
+.I libaio
+wrapper does not follow the usual C library conventions for indicating errors:
+on error it returns a negated error number
+(the negative of one of the values listed in ERRORS).
+If the system call is invoked via
+.BR syscall (2),
+then the return value follows the usual conventions for
+indicating an error: \-1, with
+.I errno
+set to a (positive) value that indicates the error.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.
+.SH SEE ALSO
+.BR io_cancel (2),
+.BR io_getevents (2),
+.BR io_setup (2),
+.BR io_submit (2),
+.BR aio (7)
+.\" .SH AUTHOR
+.\" Kent Yoder.
diff --git a/man/man2/io_getevents.2 b/man/man2/io_getevents.2
new file mode 100644
index 000000000..e426c1eae
--- /dev/null
+++ b/man/man2/io_getevents.2
@@ -0,0 +1,137 @@
+.\" Copyright (C) 2003 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH io_getevents 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+io_getevents \- read asynchronous I/O events from the completion queue
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.P
+Alternatively, Asynchronous I/O library
+.RI ( libaio ", " \-laio );
+see VERSIONS.
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/aio_abi.h>" "    /* Definition of " *io_* " types */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_io_getevents, aio_context_t " ctx_id ,
+.BI "            long " min_nr ", long " nr ", struct io_event *" events ,
+.BI "            struct timespec *" timeout );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR io_getevents (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.IR Note :
+this page describes the raw Linux system call interface.
+The wrapper function provided by
+.I libaio
+uses a different type for the
+.I ctx_id
+argument.
+See VERSIONS.
+.P
+The
+.BR io_getevents ()
+system call
+attempts to read at least \fImin_nr\fP events and
+up to \fInr\fP events from the completion queue of the AIO context
+specified by \fIctx_id\fP.
+.P
+The \fItimeout\fP argument specifies the amount of time to wait for events,
+and is specified as a relative timeout in a
+.BR timespec (3)
+structure.
+.P
+The specified time will be rounded up to the system clock granularity
+and is guaranteed not to expire early.
+.P
+Specifying
+.I timeout
+as NULL means block indefinitely until at least
+.I min_nr
+events have been obtained.
+.SH RETURN VALUE
+On success,
+.BR io_getevents ()
+returns the number of events read.
+This may be 0, or a value less than
+.IR min_nr ,
+if the
+.I timeout
+expired.
+It may also be a nonzero value less than
+.IR min_nr ,
+if the call was interrupted by a signal handler.
+.P
+For the failure return, see VERSIONS.
+.SH ERRORS
+.TP
+.B EFAULT
+Either \fIevents\fP or \fItimeout\fP is an invalid pointer.
+.TP
+.B EINTR
+Interrupted by a signal handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+\fIctx_id\fP is invalid.
+\fImin_nr\fP is out of range or \fInr\fP is
+out of range.
+.TP
+.B ENOSYS
+.BR io_getevents ()
+is not implemented on this architecture.
+.SH VERSIONS
+You probably want to use the
+.BR io_getevents ()
+wrapper function provided by
+.\" http://git.fedorahosted.org/git/?p=libaio.git
+.IR libaio .
+.P
+Note that the
+.I libaio
+wrapper function uses a different type
+.RI ( io_context_t )
+.\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
+.\" the system call.
+for the
+.I ctx_id
+argument.
+Note also that the
+.I libaio
+wrapper does not follow the usual C library conventions for indicating errors:
+on error it returns a negated error number
+(the negative of one of the values listed in ERRORS).
+If the system call is invoked via
+.BR syscall (2),
+then the return value follows the usual conventions for
+indicating an error: \-1, with
+.I errno
+set to a (positive) value that indicates the error.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.
+.SH BUGS
+An invalid
+.I ctx_id
+may cause a segmentation fault instead of generating the error
+.BR EINVAL .
+.SH SEE ALSO
+.BR io_cancel (2),
+.BR io_destroy (2),
+.BR io_setup (2),
+.BR io_submit (2),
+.BR timespec (3),
+.BR aio (7),
+.BR time (7)
+.\" .SH AUTHOR
+.\" Kent Yoder.
diff --git a/man/man2/io_setup.2 b/man/man2/io_setup.2
new file mode 100644
index 000000000..32db66422
--- /dev/null
+++ b/man/man2/io_setup.2
@@ -0,0 +1,114 @@
+.\" Copyright (C) 2003 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH io_setup 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+io_setup \- create an asynchronous I/O context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.P
+Alternatively, Asynchronous I/O library
+.RI ( libaio ", " \-laio );
+see VERSIONS.
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/aio_abi.h>" "          /* Defines needed types */"
+.P
+.BI "long io_setup(unsigned int " nr_events ", aio_context_t *" ctx_idp );
+.fi
+.P
+.IR Note :
+There is no glibc wrapper for this system call; see VERSIONS.
+.SH DESCRIPTION
+.IR Note :
+this page describes the raw Linux system call interface.
+The wrapper function provided by
+.I libaio
+uses a different type for the
+.I ctx_idp
+argument.
+See VERSIONS.
+.P
+The
+.BR io_setup ()
+system call
+creates an asynchronous I/O context suitable for concurrently processing
+\fInr_events\fP operations.
+The
+.I ctx_idp
+argument must not point to an AIO context that already exists, and must
+be initialized to 0 prior to the call.
+On successful creation of the AIO context, \fI*ctx_idp\fP is filled in
+with the resulting handle.
+.SH RETURN VALUE
+On success,
+.BR io_setup ()
+returns 0.
+For the failure return, see VERSIONS.
+.SH ERRORS
+.TP
+.B EAGAIN
+The specified \fInr_events\fP exceeds the limit of available events,
+as defined in
+.I /proc/sys/fs/aio\-max\-nr
+(see
+.BR proc (5)).
+.TP
+.B EFAULT
+An invalid pointer is passed for \fIctx_idp\fP.
+.TP
+.B EINVAL
+\fIctx_idp\fP is not initialized, or the specified \fInr_events\fP
+exceeds internal limits.
+\fInr_events\fP should be greater than 0.
+.TP
+.B ENOMEM
+Insufficient kernel resources are available.
+.TP
+.B ENOSYS
+.BR io_setup ()
+is not implemented on this architecture.
+.SH VERSIONS
+glibc does not provide a wrapper for this system call.
+You could invoke it using
+.BR syscall (2).
+But instead, you probably want to use the
+.BR io_setup ()
+wrapper function provided by
+.\" http://git.fedorahosted.org/git/?p=libaio.git
+.IR libaio .
+.P
+Note that the
+.I libaio
+wrapper function uses a different type
+.RI ( "io_context_t\ *" )
+.\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
+.\" the system call.
+for the
+.I ctx_idp
+argument.
+Note also that the
+.I libaio
+wrapper does not follow the usual C library conventions for indicating errors:
+on error it returns a negated error number
+(the negative of one of the values listed in ERRORS).
+If the system call is invoked via
+.BR syscall (2),
+then the return value follows the usual conventions for
+indicating an error: \-1, with
+.I errno
+set to a (positive) value that indicates the error.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.
+.SH SEE ALSO
+.BR io_cancel (2),
+.BR io_destroy (2),
+.BR io_getevents (2),
+.BR io_submit (2),
+.BR aio (7)
+.\" .SH AUTHOR
+.\" Kent Yoder.
diff --git a/man/man2/io_submit.2 b/man/man2/io_submit.2
new file mode 100644
index 000000000..c53ae9aaf
--- /dev/null
+++ b/man/man2/io_submit.2
@@ -0,0 +1,289 @@
+.\" Copyright (C) 2003 Free Software Foundation, Inc.
+.\" and Copyright (C) 2017 Goldwyn Rodrigues <rgoldwyn@suse.de>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH io_submit 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+io_submit \- submit asynchronous I/O blocks for processing
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.P
+Alternatively, Asynchronous I/O library
+.RI ( libaio ", " \-laio );
+see VERSIONS.
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/aio_abi.h>" "          /* Defines needed types */"
+.P
+.BI "int io_submit(aio_context_t " ctx_id ", long " nr \
+", struct iocb **" iocbpp );
+.fi
+.P
+.IR Note :
+There is no glibc wrapper for this system call; see VERSIONS.
+.SH DESCRIPTION
+.IR Note :
+this page describes the raw Linux system call interface.
+The wrapper function provided by
+.I libaio
+uses a different type for the
+.I ctx_id
+argument.
+See VERSIONS.
+.P
+The
+.BR io_submit ()
+system call
+queues \fInr\fP I/O request blocks for processing in
+the AIO context \fIctx_id\fP.
+The
+.I iocbpp
+argument should be an array of \fInr\fP AIO control blocks,
+which will be submitted to context \fIctx_id\fP.
+.P
+The
+.I iocb
+(I/O control block) structure defined in
+.I linux/aio_abi.h
+defines the parameters that control the I/O operation.
+.P
+.in +4n
+.EX
+#include <linux/aio_abi.h>
+\&
+struct iocb {
+    __u64   aio_data;
+    __u32   PADDED(aio_key, aio_rw_flags);
+    __u16   aio_lio_opcode;
+    __s16   aio_reqprio;
+    __u32   aio_fildes;
+    __u64   aio_buf;
+    __u64   aio_nbytes;
+    __s64   aio_offset;
+    __u64   aio_reserved2;
+    __u32   aio_flags;
+    __u32   aio_resfd;
+};
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I aio_data
+This data is copied into the
+.I data
+field of the
+.I io_event
+structure upon I/O completion (see
+.BR io_getevents (2)).
+.TP
+.I aio_key
+This is an internal field used by the kernel.
+Do not modify this field after an
+.BR io_submit ()
+call.
+.TP
+.I aio_rw_flags
+This defines the R/W flags passed with structure.
+The valid values are:
+.RS
+.TP
+.BR RWF_APPEND " (since Linux 4.16)"
+.\" commit e1fc742e14e01d84d9693c4aca4ab23da65811fb
+Append data to the end of the file.
+See the description of the flag of the same name in
+.BR pwritev2 (2)
+as well as the description of
+.B O_APPEND
+in
+.BR open (2).
+The
+.I aio_offset
+field is ignored.
+The file offset is not changed.
+.TP
+.BR RWF_DSYNC " (since Linux 4.13)"
+Write operation complete according to requirement of
+synchronized I/O data integrity.
+See the description of the flag of the same name in
+.BR pwritev2 (2)
+as well the description of
+.B O_DSYNC
+in
+.BR open (2).
+.TP
+.BR RWF_HIPRI " (since Linux 4.13)"
+High priority request, poll if possible
+.TP
+.BR RWF_NOWAIT " (since Linux 4.14)"
+Don't wait if the I/O will block for operations such as
+file block allocations, dirty page flush, mutex locks,
+or a congested block device inside the kernel.
+If any of these conditions are met, the control block is returned
+immediately with a return value of
+.B \-EAGAIN
+in the
+.I res
+field of the
+.I io_event
+structure (see
+.BR io_getevents (2)).
+.TP
+.BR RWF_SYNC " (since Linux 4.13)"
+Write operation complete according to requirement of
+synchronized I/O file integrity.
+See the description of the flag of the same name in
+.BR pwritev2 (2)
+as well the description of
+.B O_SYNC
+in
+.BR open (2).
+.RE
+.TP
+.I aio_lio_opcode
+This defines the type of I/O to be performed by the
+.I iocb
+structure.
+The
+valid values are defined by the enum defined in
+.IR linux/aio_abi.h :
+.IP
+.in +4n
+.EX
+enum {
+    IOCB_CMD_PREAD = 0,
+    IOCB_CMD_PWRITE = 1,
+    IOCB_CMD_FSYNC = 2,
+    IOCB_CMD_FDSYNC = 3,
+    IOCB_CMD_POLL = 5,
+    IOCB_CMD_NOOP = 6,
+    IOCB_CMD_PREADV = 7,
+    IOCB_CMD_PWRITEV = 8,
+};
+.EE
+.in
+.TP
+.I aio_reqprio
+This defines the requests priority.
+.TP
+.I aio_fildes
+The file descriptor on which the I/O operation is to be performed.
+.TP
+.I aio_buf
+This is the buffer used to transfer data for a read or write operation.
+.TP
+.I aio_nbytes
+This is the size of the buffer pointed to by
+.IR aio_buf .
+.TP
+.I aio_offset
+This is the file offset at which the I/O operation is to be performed.
+.TP
+.I aio_flags
+This is the set of flags associated with the
+.I iocb
+structure.
+The valid values are:
+.RS
+.TP
+.B IOCB_FLAG_RESFD
+Asynchronous I/O control must signal the file
+descriptor mentioned in
+.I aio_resfd
+upon completion.
+.TP
+.BR IOCB_FLAG_IOPRIO " (since Linux 4.18)"
+.\" commit d9a08a9e616beeccdbd0e7262b7225ffdfa49e92
+Interpret the
+.I aio_reqprio
+field as an
+.B IOPRIO_VALUE
+as defined by
+.IR linux/ioprio.h .
+.RE
+.TP
+.I aio_resfd
+The file descriptor to signal in the event of asynchronous I/O completion.
+.SH RETURN VALUE
+On success,
+.BR io_submit ()
+returns the number of \fIiocb\fPs submitted (which may be
+less than \fInr\fP, or 0 if \fInr\fP is zero).
+For the failure return, see VERSIONS.
+.SH ERRORS
+.TP
+.B EAGAIN
+Insufficient resources are available to queue any \fIiocb\fPs.
+.TP
+.B EBADF
+The file descriptor specified in the first \fIiocb\fP is invalid.
+.TP
+.B EFAULT
+One of the data structures points to invalid data.
+.TP
+.B EINVAL
+The AIO context specified by \fIctx_id\fP is invalid.
+\fInr\fP is less than 0.
+The \fIiocb\fP at
+.I *iocbpp[0]
+is not properly initialized, the operation specified is invalid for the file
+descriptor in the \fIiocb\fP, or the value in the
+.I aio_reqprio
+field is invalid.
+.TP
+.B ENOSYS
+.BR io_submit ()
+is not implemented on this architecture.
+.TP
+.B EPERM
+The
+.I aio_reqprio
+field is set with the class
+.BR IOPRIO_CLASS_RT ,
+but the submitting context does not have the
+.B CAP_SYS_ADMIN
+capability.
+.SH VERSIONS
+glibc does not provide a wrapper for this system call.
+You could invoke it using
+.BR syscall (2).
+But instead, you probably want to use the
+.BR io_submit ()
+wrapper function provided by
+.\" http://git.fedorahosted.org/git/?p=libaio.git
+.IR libaio .
+.P
+Note that the
+.I libaio
+wrapper function uses a different type
+.RI ( io_context_t )
+.\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
+.\" the system call.
+for the
+.I ctx_id
+argument.
+Note also that the
+.I libaio
+wrapper does not follow the usual C library conventions for indicating errors:
+on error it returns a negated error number
+(the negative of one of the values listed in ERRORS).
+If the system call is invoked via
+.BR syscall (2),
+then the return value follows the usual conventions for
+indicating an error: \-1, with
+.I errno
+set to a (positive) value that indicates the error.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.
+.SH SEE ALSO
+.BR io_cancel (2),
+.BR io_destroy (2),
+.BR io_getevents (2),
+.BR io_setup (2),
+.BR aio (7)
+.\" .SH AUTHOR
+.\" Kent Yoder.
diff --git a/man/man2/ioctl.2 b/man/man2/ioctl.2
new file mode 100644
index 000000000..5b8c28a9c
--- /dev/null
+++ b/man/man2/ioctl.2
@@ -0,0 +1,231 @@
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)ioctl.2	6.4 (Berkeley) 3/10/91
+.\"
+.\" Modified 1993-07-23 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1999-06-25 by Rachael Munns <vashti@dream.org.uk>
+.\" Modified 2000-09-21 by Andries Brouwer <aeb@cwi.nl>
+.\"
+.TH ioctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl \- control device
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " fd ", unsigned long " op ", ...);" "\f[R]  /* glibc, BSD */\f[]"
+.BI "int ioctl(int " fd ", int " op ", ...);" "\f[R]            /* musl, other UNIX */\f[]"
+.fi
+.SH DESCRIPTION
+The
+.BR ioctl ()
+system call manipulates the underlying device parameters of special files.
+In particular, many operating characteristics of character special files
+(e.g., terminals) may be controlled with
+.BR ioctl ()
+operations.
+The argument
+.I fd
+must be an open file descriptor.
+.P
+The second argument is a device-dependent operation code.
+The third argument is an untyped pointer to memory.
+It's traditionally
+.BI "char *" argp
+(from the days before
+.B "void *"
+was valid C), and will be so named for this discussion.
+.P
+An
+.BR ioctl ()
+.I op
+has encoded in it whether the argument is an
+.I in
+parameter or
+.I out
+parameter, and the size of the argument
+.I argp
+in bytes.
+Macros and defines used in specifying an
+.BR ioctl ()
+.I op
+are located in the file
+.IR <sys/ioctl.h> .
+See NOTES.
+.SH RETURN VALUE
+Usually, on success zero is returned.
+A few
+.BR ioctl ()
+operations use the return value as an output parameter
+and return a nonnegative value on success.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+.I argp
+references an inaccessible memory area.
+.TP
+.B EINVAL
+.I op
+or
+.I argp
+is not valid.
+.TP
+.B ENOTTY
+.I fd
+is not associated with a character special device.
+.TP
+.B ENOTTY
+The specified operation does not apply to the kind of object that the
+file descriptor
+.I fd
+references.
+.SH VERSIONS
+Arguments, returns, and semantics of
+.BR ioctl ()
+vary according to the device driver in question (the call is used as a
+catch-all for operations that don't cleanly fit the UNIX stream I/O
+model).
+.SH STANDARDS
+None.
+.SH HISTORY
+Version\~7 AT&T UNIX has
+.PD 0
+.in +4n
+.nf
+.BI "ioctl(int " fildes ", int " op ", struct sgttyb *" argp );
+.fi
+.in
+.P
+.PD
+(where
+.B struct sgttyb
+has historically been used by
+.BR stty (2)
+and
+.BR gtty (2),
+and is polymorphic by operation type (like a
+.B void *
+would be, if it had been available)).
+.P
+SysIII documents
+.I arg
+without a type at all.
+.P
+4.3BSD has
+.PD 0
+.in +4n
+.nf
+.BI "ioctl(int " d ", unsigned long " op ", char *" argp );
+.fi
+.in
+.P
+.PD
+(with
+.B char *
+similarly in for
+.BR "void *" ).
+.P
+SysVr4 has
+.PD 0
+.in +4n
+.nf
+.BI "int ioctl(int " fildes ", int " op ", ... /* " arg " */);"
+.fi
+.in
+.P
+.PD
+.SH NOTES
+In order to use this call, one needs an open file descriptor.
+Often the
+.BR open (2)
+call has unwanted side effects, that can be avoided under Linux
+by giving it the
+.B O_NONBLOCK
+flag.
+.\"
+.SS ioctl structure
+.\" added two sections - aeb
+Ioctl
+.I op
+values are 32-bit constants.
+In principle these constants are completely arbitrary, but people have
+tried to build some structure into them.
+.P
+The old Linux situation was that of mostly 16-bit constants, where the
+last byte is a serial number, and the preceding byte(s) give a type
+indicating the driver.
+Sometimes the major number was used: 0x03
+for the
+.B HDIO_*
+ioctls, 0x06 for the
+.B LP*
+ioctls.
+And sometimes
+one or more ASCII letters were used.
+For example,
+.B TCGETS
+has value
+0x00005401, with 0x54 = \[aq]T\[aq] indicating the terminal driver, and
+.B CYGETTIMEOUT
+has value 0x00435906, with 0x43 0x59 = \[aq]C\[aq] \[aq]Y\[aq]
+indicating the cyclades driver.
+.P
+Later (0.98p5) some more information was built into the number.
+One has 2 direction bits
+(00: none, 01: write, 10: read, 11: read/write)
+followed by 14 size bits (giving the size of the argument),
+followed by an 8-bit type (collecting the ioctls in groups
+for a common purpose or a common driver), and an 8-bit
+serial number.
+.P
+The macros describing this structure live in
+.I <asm/ioctl.h>
+and are
+.B _IO(type,nr)
+and
+.BR "{_IOR,_IOW,_IOWR}(type,nr,size)" .
+They use
+.I sizeof(size)
+so that size is a
+misnomer here: this third argument is a data type.
+.P
+Note that the size bits are very unreliable: in lots of cases
+they are wrong, either because of buggy macros using
+.IR sizeof(sizeof(struct)) ,
+or because of legacy values.
+.P
+Thus, it seems that the new structure only gave disadvantages:
+it does not help in checking, but it causes varying values
+for the various architectures.
+.SH SEE ALSO
+.BR execve (2),
+.BR fcntl (2),
+.BR ioctl_console (2),
+.BR ioctl_fat (2),
+.BR ioctl_ficlone (2),
+.BR ioctl_ficlonerange (2),
+.BR ioctl_fideduperange (2),
+.BR ioctl_fslabel (2),
+.BR ioctl_getfsmap (2),
+.BR ioctl_iflags (2),
+.BR ioctl_ns (2),
+.BR ioctl_tty (2),
+.BR ioctl_userfaultfd (2),
+.BR open (2),
+.\" .BR mt (4),
+.BR sd (4),
+.BR tty (4)
diff --git a/man/man2/ioctl_console.2 b/man/man2/ioctl_console.2
new file mode 100644
index 000000000..93a992264
--- /dev/null
+++ b/man/man2/ioctl_console.2
@@ -0,0 +1,915 @@
+'\" t
+.\" Copyright (c) 1995 Jim Van Zandt <jrv@vanzandt.mv.com> and aeb
+.\" Sun Feb 26 11:46:23 MET 1995
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified, Sun Feb 26 15:04:20 1995, faith@cs.unc.edu
+.\" Modified, Thu Apr 20 22:08:17 1995, jrv@vanzandt.mv.com
+.\" Modified, Mon Sep 18 22:32:47 1995, hpa@storm.net (H. Peter Anvin)
+.\" FIXME The following are not documented:
+.\"     KDFONTOP (since Linux 2.1.111)
+.\"     KDGKBDIACRUC (since Linux 2.6.24)
+.\"     KDSKBDIACR
+.\"     KDSKBDIACRUC (since Linux 2.6.24)
+.\"     KDKBDREP (since Linux 2.1.113)
+.\"     KDMAPDISP (not implemented as at Linux 2.6.27)
+.\"     KDUNMAPDISP (not implemented as at Linux 2.6.27)
+.\"     VT_LOCKSWITCH (since Linux 1.3.47, needs CAP_SYS_TTY_CONFIG)
+.\"     VT_UNLOCKSWITCH (since Linux 1.3.47, needs CAP_SYS_TTY_CONFIG)
+.\"     VT_GETHIFONTMASK (since Linux 2.6.18)
+.\"
+.TH ioctl_console 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_console \- ioctls for console terminal and virtual consoles
+.SH DESCRIPTION
+The following Linux-specific
+.BR ioctl (2)
+operations are supported for console terminals and virtual consoles.
+Each operation requires a third argument, assumed here to be
+.IR argp .
+.TP
+.B KDGETLED
+Get state of LEDs.
+.I argp
+points to a
+.IR char .
+The lower three bits
+of
+.I *argp
+are set to the state of the LEDs, as follows:
+.TS
+l l l.
+LED_CAP 	0x04	caps lock led
+LED_NUM 	0x02	num lock led
+LED_SCR 	0x01	scroll lock led
+.TE
+.TP
+.B KDSETLED
+Set the LEDs.
+The LEDs are set to correspond to the lower three bits of the
+unsigned long integer in
+.IR argp .
+However, if a higher order bit is set,
+the LEDs revert to normal: displaying the state of the
+keyboard functions of caps lock, num lock, and scroll lock.
+.P
+Before Linux 1.1.54, the LEDs just reflected the state of the corresponding
+keyboard flags, and KDGETLED/KDSETLED would also change the keyboard
+flags.
+Since Linux 1.1.54 the LEDs can be made to display arbitrary
+information, but by default they display the keyboard flags.
+The following two ioctls are used to access the keyboard flags.
+.TP
+.B KDGKBLED
+Get keyboard flags CapsLock, NumLock, ScrollLock (not lights).
+.I argp
+points to a char which is set to the flag state.
+The low order three bits (mask 0x7) get the current flag state,
+and the low order bits of the next nibble (mask 0x70) get
+the default flag state.
+(Since Linux 1.1.54.)
+.TP
+.B KDSKBLED
+Set keyboard flags CapsLock, NumLock, ScrollLock (not lights).
+.I argp
+is an unsigned long integer that has the desired flag state.
+The low order three bits (mask 0x7) have the flag state,
+and the low order bits of the next nibble (mask 0x70) have
+the default flag state.
+(Since Linux 1.1.54.)
+.TP
+.B KDGKBTYPE
+Get keyboard type.
+This returns the value KB_101, defined as 0x02.
+.TP
+.B KDADDIO
+Add I/O port as valid.
+Equivalent to
+.IR ioperm(arg,1,1) .
+.TP
+.B KDDELIO
+Delete I/O port as valid.
+Equivalent to
+.IR ioperm(arg,1,0) .
+.TP
+.B KDENABIO
+Enable I/O to video board.
+Equivalent to
+.IR "ioperm(0x3b4, 0x3df\-0x3b4+1, 1)" .
+.TP
+.B KDDISABIO
+Disable I/O to video board.
+Equivalent to
+.IR "ioperm(0x3b4, 0x3df\-0x3b4+1, 0)" .
+.TP
+.B KDSETMODE
+Set text/graphics mode.
+.I argp
+is an unsigned integer containing one of:
+.TS
+l l.
+KD_TEXT	0x00
+KD_GRAPHICS	0x01
+.TE
+.TP
+.B KDGETMODE
+Get text/graphics mode.
+.I argp
+points to an
+.I int
+which is set to one
+of the values shown above for
+.BR KDSETMODE .
+.TP
+.B KDMKTONE
+Generate tone of specified length.
+The lower 16 bits of the unsigned long integer in
+.I argp
+specify the period in clock cycles,
+and the upper 16 bits give the duration in msec.
+If the duration is zero, the sound is turned off.
+Control returns immediately.
+For example,
+.I argp
+= (125<<16) + 0x637 would specify
+the beep normally associated with a ctrl-G.
+(Thus since Linux 0.99pl1; broken in Linux 2.1.49-50.)
+.TP
+.B KIOCSOUND
+Start or stop sound generation.
+The lower 16 bits of
+.I argp
+specify the period in clock cycles
+(that is,
+.I argp
+= 1193180/frequency).
+.I argp
+= 0 turns sound off.
+In either case, control returns immediately.
+.TP
+.B GIO_CMAP
+Get the current default color map from kernel.
+.I argp
+points to
+a 48-byte array.
+(Since Linux 1.3.3.)
+.TP
+.B PIO_CMAP
+Change the default text-mode color map.
+.I argp
+points to a
+48-byte array which contains, in order, the Red, Green, and Blue
+values for the 16 available screen colors: 0 is off, and 255 is full
+intensity.
+The default colors are, in order: black, dark red, dark
+green, brown, dark blue, dark purple, dark cyan, light grey, dark
+grey, bright red, bright green, yellow, bright blue, bright purple,
+bright cyan, and white.
+(Since Linux 1.3.3.)
+.TP
+.B GIO_FONT
+Gets 256-character screen font in expanded form.
+.I argp
+points to an 8192-byte array.
+Fails with error code
+.B EINVAL
+if the
+currently loaded font is a 512-character font, or if the console is
+not in text mode.
+.TP
+.B GIO_FONTX
+Gets screen font and associated information.
+.I argp
+points to a
+.I "struct consolefontdesc"
+(see
+.BR PIO_FONTX ).
+On call, the
+.I charcount
+field should be set to the maximum number of
+characters that would fit in the buffer pointed to by
+.IR chardata .
+On return, the
+.I charcount
+and
+.I charheight
+are filled with
+the respective data for the currently loaded font, and the
+.I chardata
+array contains the font data if the initial value of
+.I charcount
+indicated enough space was available; otherwise the
+buffer is untouched and
+.I errno
+is set to
+.BR ENOMEM .
+(Since Linux 1.3.1.)
+.TP
+.B PIO_FONT
+Sets 256-character screen font.
+Load font into the EGA/VGA character
+generator.
+.I argp
+points to an 8192-byte map, with 32 bytes per
+character.
+Only the first
+.I N
+of them are used for an 8x\fIN\fP font
+(0 <
+.I N
+<= 32).
+This call also invalidates the Unicode mapping.
+.TP
+.B PIO_FONTX
+Sets screen font and associated rendering information.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct consolefontdesc {
+    unsigned short charcount;  /* characters in font
+                                  (256 or 512) */
+    unsigned short charheight; /* scan lines per
+                                  character (1\-32) */
+    char          *chardata;   /* font data in
+                                  expanded form */
+};
+.EE
+.in
+.IP
+If necessary, the screen will be appropriately resized, and
+.B SIGWINCH
+sent to the appropriate processes.
+This call also invalidates the Unicode mapping.
+(Since Linux 1.3.1.)
+.TP
+.B PIO_FONTRESET
+Resets the screen font, size, and Unicode mapping to the bootup
+defaults.
+.I argp
+is unused, but should be set to NULL to
+ensure compatibility with future versions of Linux.
+(Since Linux 1.3.28.)
+.TP
+.B GIO_SCRNMAP
+Get screen mapping from kernel.
+.I argp
+points to an area of size
+E_TABSZ, which is loaded with the font positions used to display each
+character.
+This call is likely to return useless information if the
+currently loaded font is more than 256 characters.
+.TP
+.B GIO_UNISCRNMAP
+Get full Unicode screen mapping from kernel.
+.I argp
+points to an
+area of size
+.IR "E_TABSZ*sizeof(unsigned short)" ,
+which is loaded with the
+Unicodes each character represent.
+A special set of Unicodes,
+starting at U+F000, are used to represent "direct to font" mappings.
+(Since Linux 1.3.1.)
+.TP
+.B PIO_SCRNMAP
+Loads the "user definable" (fourth) table in the kernel which maps
+bytes into console screen symbols.
+.I argp
+points to an area of
+size E_TABSZ.
+.TP
+.B PIO_UNISCRNMAP
+Loads the "user definable" (fourth) table in the kernel which maps
+bytes into Unicodes, which are then translated into screen symbols
+according to the currently loaded Unicode-to-font map.
+Special Unicodes starting at U+F000 can be used to map directly to the font
+symbols.
+(Since Linux 1.3.1.)
+.TP
+.B GIO_UNIMAP
+Get Unicode-to-font mapping from kernel.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct unimapdesc {
+    unsigned short  entry_ct;
+    struct unipair *entries;
+};
+.EE
+.in
+.IP
+where
+.I entries
+points to an array of
+.IP
+.in +4n
+.EX
+struct unipair {
+    unsigned short unicode;
+    unsigned short fontpos;
+};
+.EE
+.in
+.IP
+(Since Linux 1.1.92.)
+.TP
+.B PIO_UNIMAP
+Put unicode-to-font mapping in kernel.
+.I argp
+points to a
+.IR "struct unimapdesc" .
+(Since Linux 1.1.92)
+.TP
+.B PIO_UNIMAPCLR
+Clear table, possibly advise hash algorithm.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct unimapinit {
+    unsigned short advised_hashsize;  /* 0 if no opinion */
+    unsigned short advised_hashstep;  /* 0 if no opinion */
+    unsigned short advised_hashlevel; /* 0 if no opinion */
+};
+.EE
+.in
+.IP
+(Since Linux 1.1.92.)
+.TP
+.B KDGKBMODE
+Gets current keyboard mode.
+.I argp
+points to a
+.I long
+which is set to one
+of these:
+.TS
+l l.
+K_RAW	0x00  /* Raw (scancode) mode */
+K_XLATE	0x01  /* Translate keycodes using keymap */
+K_MEDIUMRAW	0x02  /* Medium raw (scancode) mode */
+K_UNICODE	0x03  /* Unicode mode */
+K_OFF	0x04  /* Disabled mode; since Linux 2.6.39 */
+.\" K_OFF: commit 9fc3de9c83565fcaa23df74c2fc414bb6e7efb0a
+.TE
+.TP
+.B KDSKBMODE
+Sets current keyboard mode.
+.I argp
+is a
+.I long
+equal to one of the values shown for
+.BR KDGKBMODE .
+.TP
+.B KDGKBMETA
+Gets meta key handling mode.
+.I argp
+points to a
+.I long
+which is
+set to one of these:
+.TS
+l l l.
+K_METABIT	0x03	set high order bit
+K_ESCPREFIX	0x04	escape prefix
+.TE
+.TP
+.B KDSKBMETA
+Sets meta key handling mode.
+.I argp
+is a
+.I long
+equal to one of the values shown above for
+.BR KDGKBMETA .
+.TP
+.B KDGKBENT
+Gets one entry in key translation table (keycode to action code).
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct kbentry {
+    unsigned char  kb_table;
+    unsigned char  kb_index;
+    unsigned short kb_value;
+};
+.EE
+.in
+.IP
+with the first two members filled in:
+.I kb_table
+selects the key table (0 <=
+.I kb_table
+< MAX_NR_KEYMAPS),
+and
+.I kb_index
+is the keycode (0 <=
+.I kb_index
+< NR_KEYS).
+.I kb_value
+is set to the corresponding action code,
+or K_HOLE if there is no such key,
+or K_NOSUCHMAP if
+.I kb_table
+is invalid.
+.TP
+.B KDSKBENT
+Sets one entry in translation table.
+.I argp
+points to a
+.IR "struct kbentry" .
+.TP
+.B KDGKBSENT
+Gets one function key string.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct kbsentry {
+    unsigned char kb_func;
+    unsigned char kb_string[512];
+};
+.EE
+.in
+.IP
+.I kb_string
+is set to the (null-terminated) string corresponding to
+the
+.IR kb_func th
+function key action code.
+.TP
+.B KDSKBSENT
+Sets one function key string entry.
+.I argp
+points to a
+.IR "struct kbsentry" .
+.TP
+.B KDGKBDIACR
+Read kernel accent table.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct kbdiacrs {
+    unsigned int   kb_cnt;
+    struct kbdiacr kbdiacr[256];
+};
+.EE
+.in
+.IP
+where
+.I kb_cnt
+is the number of entries in the array, each of which
+is a
+.IP
+.in +4n
+.EX
+struct kbdiacr {
+    unsigned char diacr;
+    unsigned char base;
+    unsigned char result;
+};
+.EE
+.in
+.TP
+.B KDGETKEYCODE
+Read kernel keycode table entry (scan code to keycode).
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct kbkeycode {
+    unsigned int scancode;
+    unsigned int keycode;
+};
+.EE
+.in
+.IP
+.I keycode
+is set to correspond to the given
+.IR scancode .
+(89 <=
+.I scancode
+<= 255 only.
+For 1 <=
+.I scancode
+<= 88,
+.IR keycode == scancode .)
+(Since Linux 1.1.63.)
+.TP
+.B KDSETKEYCODE
+Write kernel keycode table entry.
+.I argp
+points to a
+.IR "struct kbkeycode" .
+(Since Linux 1.1.63.)
+.TP
+.B KDSIGACCEPT
+The calling process indicates its willingness to accept the signal
+.I argp
+when it is generated by pressing an appropriate key combination.
+(1 <=
+.I argp
+<= NSIG).
+(See
+.IR spawn_console ()
+in
+.IR linux/drivers/char/keyboard.c .)
+.TP
+.B VT_OPENQRY
+Returns the first available (non-opened) console.
+.I argp
+points to an
+.I int
+which is set to the
+number of the vt (1 <=
+.I *argp
+<= MAX_NR_CONSOLES).
+.TP
+.B VT_GETMODE
+Get mode of active vt.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct vt_mode {
+    char  mode;    /* vt mode */
+    char  waitv;   /* if set, hang on writes if not active */
+    short relsig;  /* signal to raise on release op */
+    short acqsig;  /* signal to raise on acquisition */
+    short frsig;   /* unused (set to 0) */
+};
+.EE
+.in
+.IP
+which is set to the mode of the active vt.
+.I mode
+is set to one of these values:
+.TS
+l l.
+VT_AUTO	auto vt switching
+VT_PROCESS	process controls switching
+VT_ACKACQ	acknowledge switch
+.TE
+.TP
+.B VT_SETMODE
+Set mode of active vt.
+.I argp
+points to a
+.IR "struct vt_mode" .
+.TP
+.B VT_GETSTATE
+Get global vt state info.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct vt_stat {
+    unsigned short v_active;  /* active vt */
+    unsigned short v_signal;  /* signal to send */
+    unsigned short v_state;   /* vt bit mask */
+};
+.EE
+.in
+.IP
+For each vt in use, the corresponding bit in the
+.I v_state
+member is set.
+(Linux 1.0 through Linux 1.1.92.)
+.TP
+.B VT_RELDISP
+Release a display.
+.TP
+.B VT_ACTIVATE
+Switch to vt
+.I argp
+(1 <=
+.I argp
+<= MAX_NR_CONSOLES).
+.TP
+.B VT_WAITACTIVE
+Wait until vt
+.I argp
+has been activated.
+.TP
+.B VT_DISALLOCATE
+Deallocate the memory associated with vt
+.IR argp .
+(Since Linux 1.1.54.)
+.TP
+.B VT_RESIZE
+Set the kernel's idea of screensize.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct vt_sizes {
+    unsigned short v_rows;       /* # rows */
+    unsigned short v_cols;       /* # columns */
+    unsigned short v_scrollsize; /* no longer used */
+};
+.EE
+.in
+.IP
+Note that this does not change the videomode.
+See
+.BR resizecons (8).
+(Since Linux 1.1.54.)
+.TP
+.B VT_RESIZEX
+Set the kernel's idea of various screen parameters.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct vt_consize {
+    unsigned short v_rows;  /* number of rows */
+    unsigned short v_cols;  /* number of columns */
+    unsigned short v_vlin;  /* number of pixel rows
+                               on screen */
+    unsigned short v_clin;  /* number of pixel rows
+                               per character */
+    unsigned short v_vcol;  /* number of pixel columns
+                               on screen */
+    unsigned short v_ccol;  /* number of pixel columns
+                               per character */
+};
+.EE
+.in
+.IP
+Any parameter may be set to zero, indicating "no change", but if
+multiple parameters are set, they must be self-consistent.
+Note that this does not change the videomode.
+See
+.BR resizecons (8).
+(Since Linux 1.3.3.)
+.P
+The action of the following ioctls depends on the first byte in the struct
+pointed to by
+.IR argp ,
+referred to here as the
+.IR subcode .
+These are legal only for the superuser or the owner of the current terminal.
+Symbolic
+.IR subcode s
+are available in
+.I <linux/tiocl.h>
+since
+Linux 2.5.71.
+.TP
+.BR TIOCLINUX ", " subcode = 0
+Dump the screen.
+Disappeared in Linux 1.1.92.
+(With Linux 1.1.92 or later, read from
+.I /dev/vcsN
+or
+.I /dev/vcsaN
+instead.)
+.TP
+.BR TIOCLINUX ", " subcode = 1
+Get task information.
+Disappeared in Linux 1.1.92.
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_SETSEL
+Set selection.
+.I argp
+points to a
+.IP
+.in +4n
+.EX
+struct {
+    char  subcode;
+    short xs, ys, xe, ye;
+    short sel_mode;
+};
+.EE
+.in
+.IP
+.I xs
+and
+.I ys
+are the starting column and row.
+.I xe
+and
+.I ye
+are the ending
+column and row.
+(Upper left corner is row=column=1.)
+.I sel_mode
+is 0 for character-by-character selection,
+1 for word-by-word selection,
+or 2 for line-by-line selection.
+The indicated screen characters are highlighted and saved
+in a kernel buffer.
+.IP
+Since Linux 6.7, using this subcode requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_PASTESEL
+Paste selection.
+The characters in the selection buffer are
+written to
+.IR fd .
+.IP
+Since Linux 6.7, using this subcode requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_UNBLANKSCREEN
+Unblank the screen.
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_SELLOADLUT
+Sets contents of a 256-bit look up table defining characters in a "word",
+for word-by-word selection.
+(Since Linux 1.1.32.)
+.IP
+Since Linux 6.7, using this subcode requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_GETSHIFTSTATE
+.I argp
+points to a char which is set to the value of the kernel
+variable
+.IR shift_state .
+(Since Linux 1.1.32.)
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_GETMOUSEREPORTING
+.I argp
+points to a char which is set to the value of the kernel
+variable
+.IR report_mouse .
+(Since Linux 1.1.33.)
+.TP
+.BR TIOCLINUX ", " subcode = 8
+Dump screen width and height, cursor position, and all the
+character-attribute pairs.
+(Linux 1.1.67 through Linux 1.1.91 only.
+With Linux 1.1.92 or later, read from
+.I /dev/vcsa*
+instead.)
+.TP
+.BR TIOCLINUX ", " subcode = 9
+Restore screen width and height, cursor position, and all the
+character-attribute pairs.
+(Linux 1.1.67 through Linux 1.1.91 only.
+With Linux 1.1.92 or later, write to
+.I /dev/vcsa*
+instead.)
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_SETVESABLANK
+Handles the Power Saving
+feature of the new generation of monitors.
+VESA screen blanking mode is set to
+.IR argp[1] ,
+which governs what
+screen blanking does:
+.RS
+.TP
+.B 0
+Screen blanking is disabled.
+.TP
+.B 1
+The current video adapter
+register settings are saved, then the controller is programmed to turn off
+the vertical synchronization pulses.
+This puts the monitor into "standby" mode.
+If your monitor has an Off_Mode timer, then
+it will eventually power down by itself.
+.TP
+.B 2
+The current settings are saved, then both the vertical and horizontal
+synchronization pulses are turned off.
+This puts the monitor into "off" mode.
+If your monitor has no Off_Mode timer,
+or if you want your monitor to power down immediately when the
+blank_timer times out, then you choose this option.
+.RI ( Caution:
+Powering down frequently will damage the monitor.)
+(Since Linux 1.1.76.)
+.RE
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_SETKMSGREDIRECT
+Change target of kernel messages ("console"):
+by default, and if this is set to
+.BR 0 ,
+messages are written to the currently active VT.
+The VT to write to is a single byte following
+.BR subcode .
+(Since Linux 2.5.36.)
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_GETFGCONSOLE
+Returns the number of VT currently in foreground.
+(Since Linux 2.5.36.)
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_SCROLLCONSOLE
+Scroll the foreground VT by the specified amount of
+.I lines
+down,
+or half the screen if
+.BR 0 .
+.I lines
+is *(((int32_t *)&subcode) + 1).
+(Since Linux 2.5.67.)
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_BLANKSCREEN
+Blank the foreground VT, ignoring "pokes" (typing):
+can only be unblanked explicitly (by switching VTs, to text mode, etc.).
+(Since Linux 2.5.71.)
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_BLANKEDSCREEN
+Returns the number of VT currently blanked,
+.B 0
+if none.
+(Since Linux 2.5.71.)
+.TP
+.BR TIOCLINUX ", " subcode = 16
+Never used.
+.TP
+.BR TIOCLINUX ", " subcode = TIOCL_GETKMSGREDIRECT
+Returns target of kernel messages.
+(Since Linux 2.6.17.)
+.SH RETURN VALUE
+On success, 0 is returned (except where indicated).
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The file descriptor is invalid.
+.TP
+.B EINVAL
+The file descriptor or
+.I argp
+is invalid.
+.TP
+.B ENOTTY
+The file descriptor is not associated with a character special device,
+or the specified operation does not apply to it.
+.TP
+.B EPERM
+Insufficient permission.
+.SH NOTES
+.BR Warning :
+Do not regard this man page as documentation of the Linux console ioctls.
+This is provided for the curious only, as an alternative to reading the
+source.
+Ioctl's are undocumented Linux internals, liable to be changed
+without warning.
+(And indeed, this page more or less describes the
+situation as of kernel version 1.1.94;
+there are many minor and not-so-minor
+differences with earlier versions.)
+.P
+Very often, ioctls are introduced for communication between the
+kernel and one particular well-known program (fdisk, hdparm, setserial,
+tunelp, loadkeys, selection, setfont, etc.), and their behavior will be
+changed when required by this particular program.
+.P
+Programs using these ioctls will not be portable to other versions
+of UNIX, will not work on older versions of Linux, and will not work
+on future versions of Linux.
+.P
+Use POSIX functions.
+.SH SEE ALSO
+.BR dumpkeys (1),
+.BR kbd_mode (1),
+.BR loadkeys (1),
+.BR mknod (1),
+.BR setleds (1),
+.BR setmetamode (1),
+.BR execve (2),
+.BR fcntl (2),
+.BR ioctl_tty (2),
+.BR ioperm (2),
+.BR termios (3),
+.BR console_codes (4),
+.BR mt (4),
+.BR sd (4),
+.BR tty (4),
+.BR ttyS (4),
+.BR vcs (4),
+.BR vcsa (4),
+.BR charsets (7),
+.BR mapscrn (8),
+.BR resizecons (8),
+.BR setfont (8)
+.P
+.IR /usr/include/linux/kd.h ,
+.I /usr/include/linux/vt.h
diff --git a/man/man2/ioctl_fat.2 b/man/man2/ioctl_fat.2
new file mode 100644
index 000000000..294acc6ff
--- /dev/null
+++ b/man/man2/ioctl_fat.2
@@ -0,0 +1,489 @@
+.\" Copyright (C) 2014, Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH ioctl_fat 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_fat \- manipulating the FAT filesystem
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/msdos_fs.h>" "     /* Definition of [" V ] FAT_* " and"
+.BR "                                   ATTR_* " constants */"
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " fd ", FAT_IOCTL_GET_ATTRIBUTES, uint32_t *" attr );
+.BI "int ioctl(int " fd ", FAT_IOCTL_SET_ATTRIBUTES, uint32_t *" attr );
+.BI "int ioctl(int " fd ", FAT_IOCTL_GET_VOLUME_ID, uint32_t *" id );
+.BI "int ioctl(int " fd ", VFAT_IOCTL_READDIR_BOTH,"
+.BI "          struct __fat_dirent " entry [2]);
+.BI "int ioctl(int " fd ", VFAT_IOCTL_READDIR_SHORT,"
+.BI "          struct __fat_dirent " entry [2]);
+.fi
+.SH DESCRIPTION
+The
+.BR ioctl (2)
+system call can be used to read and write metadata of FAT filesystems that
+are not accessible using other system calls.
+.SS Reading and setting file attributes
+Files and directories in the FAT filesystem possess an attribute bit mask that
+can be read with
+.B FAT_IOCTL_GET_ATTRIBUTES
+and written with
+.BR FAT_IOCTL_SET_ATTRIBUTES .
+.P
+The
+.I fd
+argument contains a file descriptor for a file or directory.
+It is sufficient to create the file descriptor by calling
+.BR open (2)
+with the
+.B O_RDONLY
+flag.
+.P
+The
+.I attr
+argument contains a pointer to a bit mask.
+The bits of the bit mask are:
+.TP
+.B ATTR_RO
+This bit specifies that the file or directory is read-only.
+.TP
+.B ATTR_HIDDEN
+This bit specifies that the file or directory is hidden.
+.TP
+.B ATTR_SYS
+This bit specifies that the file is a system file.
+.TP
+.B ATTR_VOLUME
+This bit specifies that the file is a volume label.
+This attribute is read-only.
+.TP
+.B ATTR_DIR
+This bit specifies that this is a directory.
+This attribute is read-only.
+.TP
+.B ATTR_ARCH
+This bit indicates that this file or directory should be archived.
+It is set when a file is created or modified.
+It is reset by an archiving system.
+.P
+The zero value
+.B ATTR_NONE
+can be used to indicate that no attribute bit is set.
+.SS Reading the volume ID
+FAT filesystems are identified by a volume ID.
+The volume ID can be read with
+.BR FAT_IOCTL_GET_VOLUME_ID .
+.P
+The
+.I fd
+argument can be a file descriptor for any file or directory of the
+filesystem.
+It is sufficient to create the file descriptor by calling
+.BR open (2)
+with the
+.B O_RDONLY
+flag.
+.P
+The
+.I id
+argument is a pointer to the field that will be filled with the volume ID.
+Typically the volume ID is displayed to the user as a group of two
+16-bit fields:
+.P
+.in +4n
+.EX
+printf("Volume ID %04x\-%04x\en", id >> 16, id & 0xFFFF);
+.EE
+.in
+.SS Reading short filenames of a directory
+A file or directory on a FAT filesystem always has a short filename
+consisting of up to 8 capital letters, optionally followed by a period
+and up to 3 capital letters for the file extension.
+If the actual filename does not fit into this scheme, it is stored
+as a long filename of up to 255 UTF-16 characters.
+.P
+The short filenames in a directory can be read with
+.BR VFAT_IOCTL_READDIR_SHORT .
+.B VFAT_IOCTL_READDIR_BOTH
+reads both the short and the long filenames.
+.P
+The
+.I fd
+argument must be a file descriptor for a directory.
+It is sufficient to create the file descriptor by calling
+.BR open (2)
+with the
+.B O_RDONLY
+flag.
+The file descriptor can be used only once to iterate over the directory
+entries by calling
+.BR ioctl (2)
+repeatedly.
+.P
+The
+.I entry
+argument is a two-element array of the following structures:
+.P
+.in +4n
+.EX
+struct __fat_dirent {
+    long            d_ino;
+    __kernel_off_t  d_off;
+    uint32_t short  d_reclen;
+    char            d_name[256];
+};
+.EE
+.in
+.P
+The first entry in the array is for the short filename.
+The second entry is for the long filename.
+.P
+The
+.I d_ino
+and
+.I d_off
+fields are filled only for long filenames.
+The
+.I d_ino
+field holds the inode number of the directory.
+The
+.I d_off
+field holds the offset of the file entry in the directory.
+As these values are not available for short filenames, the user code should
+simply ignore them.
+.P
+The field
+.I d_reclen
+contains the length of the filename in the field
+.IR d_name .
+To keep backward compatibility, a length of 0 for the short filename signals
+that the end of the directory has been reached.
+However, the preferred method for detecting the end of the directory
+is to test the
+.BR ioctl (2)
+return value.
+If no long filename exists, field
+.I d_reclen
+is set to 0 and
+.I d_name
+is a character string of length 0 for the long filename.
+.SH RETURN VALUE
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+For
+.B VFAT_IOCTL_READDIR_BOTH
+and
+.B VFAT_IOCTL_READDIR_SHORT
+a return value of 1 signals that a new directory entry has been read and
+a return value of 0 signals that the end of the directory has been reached.
+.SH ERRORS
+.TP
+.B ENOENT
+This error is returned by
+.B VFAT_IOCTL_READDIR_BOTH
+and
+.B VFAT_IOCTL_READDIR_SHORT
+if the file descriptor
+.I fd
+refers to a removed, but still open directory.
+.TP
+.B ENOTDIR
+This error is returned by
+.B VFAT_IOCTL_READDIR_BOTH
+and
+.B VFAT_IOCTL_READDIR_SHORT
+if the file descriptor
+.I fd
+does not refer to a directory.
+.TP
+.B ENOTTY
+The file descriptor
+.I fd
+does not refer to an object in a FAT filesystem.
+.P
+For further error values, see
+.BR ioctl (2).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.B VFAT_IOCTL_READDIR_BOTH
+.TQ
+.B VFAT_IOCTL_READDIR_SHORT
+Linux 2.0.
+.TP
+.B FAT_IOCTL_GET_ATTRIBUTES
+.TQ
+.B FAT_IOCTL_SET_ATTRIBUTES
+.\" just before we got Git history
+Linux 2.6.12.
+.TP
+.B FAT_IOCTL_GET_VOLUME_ID
+Linux 3.11.
+.\" commit 6e5b93ee55d401f1619092fb675b57c28c9ed7ec
+.SH EXAMPLES
+.SS Toggling the archive flag
+The following program demonstrates the usage of
+.BR ioctl (2)
+to manipulate file attributes.
+The program reads and displays the archive attribute of a file.
+After inverting the value of the attribute,
+the program reads and displays the attribute again.
+.P
+The following was recorded when applying the program for the file
+.IR /mnt/user/foo :
+.P
+.in +4n
+.EX
+# ./toggle_fat_archive_flag /mnt/user/foo
+Archive flag is set
+Toggling archive flag
+Archive flag is not set
+.EE
+.in
+.SS Program source (toggle_fat_archive_flag.c)
+\&
+.\" SRC BEGIN (toggle_fat_archive_flag.c)
+.EX
+#include <fcntl.h>
+#include <linux/msdos_fs.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+\&
+/*
+ * Read file attributes of a file on a FAT filesystem.
+ * Output the state of the archive flag.
+ */
+static uint32_t
+readattr(int fd)
+{
+    int       ret;
+    uint32_t  attr;
+\&
+    ret = ioctl(fd, FAT_IOCTL_GET_ATTRIBUTES, &attr);
+    if (ret == \-1) {
+        perror("ioctl");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (attr & ATTR_ARCH)
+        printf("Archive flag is set\en");
+    else
+        printf("Archive flag is not set\en");
+\&
+    return attr;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int       fd;
+    int       ret;
+    uint32_t  attr;
+\&
+    if (argc != 2) {
+        printf("Usage: %s FILENAME\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fd = open(argv[1], O_RDONLY);
+    if (fd == \-1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Read and display the FAT file attributes.
+     */
+    attr = readattr(fd);
+\&
+    /*
+     * Invert archive attribute.
+     */
+    printf("Toggling archive flag\en");
+    attr \[ha]= ATTR_ARCH;
+\&
+    /*
+     * Write the changed FAT file attributes.
+     */
+    ret = ioctl(fd, FAT_IOCTL_SET_ATTRIBUTES, &attr);
+    if (ret == \-1) {
+        perror("ioctl");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Read and display the FAT file attributes.
+     */
+    readattr(fd);
+\&
+    close(fd);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SS Reading the volume ID
+The following program demonstrates the use of
+.BR ioctl (2)
+to display the volume ID of a FAT filesystem.
+.P
+The following output was recorded when applying the program for
+directory
+.IR /mnt/user :
+.P
+.in +4n
+.EX
+$ ./display_fat_volume_id /mnt/user
+Volume ID 6443\-6241
+.EE
+.in
+.SS Program source (display_fat_volume_id.c)
+\&
+.\" SRC BEGIN (display_fat_volume_id.c)
+.EX
+#include <fcntl.h>
+#include <linux/msdos_fs.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int       fd;
+    int       ret;
+    uint32_t  id;
+\&
+    if (argc != 2) {
+        printf("Usage: %s FILENAME\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fd = open(argv[1], O_RDONLY);
+    if (fd == \-1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Read volume ID.
+     */
+    ret = ioctl(fd, FAT_IOCTL_GET_VOLUME_ID, &id);
+    if (ret == \-1) {
+        perror("ioctl");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Format the output as two groups of 16 bits each.
+     */
+    printf("Volume ID %04x\-%04x\en", id >> 16, id & 0xFFFF);
+\&
+    close(fd);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SS Listing a directory
+The following program demonstrates the use of
+.BR ioctl (2)
+to list a directory.
+.P
+The following was recorded when applying the program to the directory
+.IR /mnt/user :
+.P
+.in +4n
+.EX
+$ \fB./fat_dir /mnt/user\fP
+\&. \-> \[aq]\[aq]
+\&.. \-> \[aq]\[aq]
+ALONGF\[ti]1.TXT \-> \[aq]a long filename.txt\[aq]
+UPPER.TXT \-> \[aq]\[aq]
+LOWER.TXT \-> \[aq]lower.txt\[aq]
+.EE
+.in
+.\"
+.SS Program source
+.in +4n
+.\" SRC BEGIN (ioctl_fat.c)
+.EX
+#include <fcntl.h>
+#include <linux/msdos_fs.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int                  fd;
+    int                  ret;
+    struct __fat_dirent  entry[2];
+\&
+    if (argc != 2) {
+        printf("Usage: %s DIRECTORY\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Open file descriptor for the directory.
+     */
+    fd = open(argv[1], O_RDONLY | O_DIRECTORY);
+    if (fd == \-1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (;;) {
+\&
+        /*
+         * Read next directory entry.
+         */
+        ret = ioctl(fd, VFAT_IOCTL_READDIR_BOTH, entry);
+\&
+        /*
+         * If an error occurs, the return value is \-1.
+         * If the end of the directory list has been reached,
+         * the return value is 0.
+         * For backward compatibility the end of the directory
+         * list is also signaled by d_reclen == 0.
+         */
+        if (ret < 1)
+            break;
+\&
+        /*
+         * Write both the short name and the long name.
+         */
+        printf("%s \-> \[aq]%s\[aq]\en", entry[0].d_name, entry[1].d_name);
+    }
+\&
+    if (ret == \-1) {
+        perror("VFAT_IOCTL_READDIR_BOTH");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Close the file descriptor.
+     */
+    close(fd);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR ioctl (2)
diff --git a/man/man2/ioctl_ficlone.2 b/man/man2/ioctl_ficlone.2
new file mode 100644
index 000000000..19bb3482d
--- /dev/null
+++ b/man/man2/ioctl_ficlone.2
@@ -0,0 +1 @@
+.so man2/ioctl_ficlonerange.2
diff --git a/man/man2/ioctl_ficlonerange.2 b/man/man2/ioctl_ficlonerange.2
new file mode 100644
index 000000000..63a430dd4
--- /dev/null
+++ b/man/man2/ioctl_ficlonerange.2
@@ -0,0 +1,129 @@
+.\" Copyright (c) 2016, Oracle.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH ioctl_ficlonerange 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_ficlonerange, ioctl_ficlone \-
+share some the data of one file with another file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fs.h>" "        /* Definition of " FICLONE* " constants */"
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " dest_fd ", FICLONERANGE, struct file_clone_range *" arg );
+.BI "int ioctl(int " dest_fd ", FICLONE, int " src_fd );
+.fi
+.SH DESCRIPTION
+If a filesystem supports files sharing physical storage between multiple
+files ("reflink"), this
+.BR ioctl (2)
+operation can be used to make some of the data in the
+.I src_fd
+file appear in the
+.I dest_fd
+file by sharing the underlying storage, which is faster than making a separate
+physical copy of the data.
+Both files must reside within the same filesystem.
+If a file write should occur to a shared region,
+the filesystem must ensure that the changes remain private to the file being
+written.
+This behavior is commonly referred to as "copy on write".
+.P
+This ioctl reflinks up to
+.I src_length
+bytes from file descriptor
+.I src_fd
+at offset
+.I src_offset
+into the file
+.I dest_fd
+at offset
+.IR dest_offset ,
+provided that both are files.
+If
+.I src_length
+is zero, the ioctl reflinks to the end of the source file.
+This information is conveyed in a structure of
+the following form:
+.P
+.in +4n
+.EX
+struct file_clone_range {
+    __s64 src_fd;
+    __u64 src_offset;
+    __u64 src_length;
+    __u64 dest_offset;
+};
+.EE
+.in
+.P
+Clones are atomic with regards to concurrent writes, so no locks need to be
+taken to obtain a consistent cloned copy.
+.P
+The
+.B FICLONE
+ioctl clones entire files.
+.SH RETURN VALUE
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Error codes can be one of, but are not limited to, the following:
+.TP
+.B EBADF
+.I src_fd
+is not open for reading;
+.I dest_fd
+is not open for writing or is open for append-only writes;
+or the filesystem which
+.I src_fd
+resides on does not support reflink.
+.TP
+.B EINVAL
+The filesystem does not support reflinking the ranges of the given files.
+This error can also appear if either file descriptor represents
+a device, FIFO, or socket.
+Disk filesystems generally require the offset and length arguments
+to be aligned to the fundamental block size.
+XFS and Btrfs do not support
+overlapping reflink ranges in the same file.
+.TP
+.B EISDIR
+One of the files is a directory and the filesystem does not support shared
+regions in directories.
+.TP
+.B EOPNOTSUPP
+This can appear if the filesystem does not support reflinking either file
+descriptor, or if either file descriptor refers to special inodes.
+.TP
+.B EPERM
+.I dest_fd
+is immutable.
+.TP
+.B ETXTBSY
+One of the files is a swap file.
+Swap files cannot share storage.
+.TP
+.B EXDEV
+.IR dest_fd " and " src_fd
+are not on the same mounted filesystem.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 4.5.
+.P
+They were previously known as
+.B BTRFS_IOC_CLONE
+and
+.BR BTRFS_IOC_CLONE_RANGE ,
+and were private to Btrfs.
+.SH NOTES
+Because a copy-on-write operation requires the allocation of new storage, the
+.BR fallocate (2)
+operation may unshare shared blocks to guarantee that subsequent writes will
+not fail because of lack of disk space.
+.SH SEE ALSO
+.BR ioctl (2)
diff --git a/man/man2/ioctl_fideduperange.2 b/man/man2/ioctl_fideduperange.2
new file mode 100644
index 000000000..1942c8fd0
--- /dev/null
+++ b/man/man2/ioctl_fideduperange.2
@@ -0,0 +1,200 @@
+.\" Copyright (c) 2016, Oracle.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH ioctl_fideduperange 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_fideduperange \- share some the data of one file with another file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fs.h>" "      /* Definition of " FIDEDUPERANGE " and"
+.BR "                              FILE_DEDUPE_* " constants */
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " src_fd ", FIDEDUPERANGE, struct file_dedupe_range *" arg );
+.fi
+.SH DESCRIPTION
+If a filesystem supports files sharing physical storage between multiple
+files, this
+.BR ioctl (2)
+operation can be used to make some of the data in the
+.B src_fd
+file appear in the
+.B dest_fd
+file by sharing the underlying storage if the file data is identical
+("deduplication").
+Both files must reside within the same filesystem.
+This reduces storage consumption by allowing the filesystem
+to store one shared copy of the data.
+If a file write should occur to a shared
+region, the filesystem must ensure that the changes remain private to the file
+being written.
+This behavior is commonly referred to as "copy on write".
+.P
+This ioctl performs the "compare and share if identical" operation on up to
+.I src_length
+bytes from file descriptor
+.I src_fd
+at offset
+.IR src_offset .
+This information is conveyed in a structure of the following form:
+.P
+.in +4n
+.EX
+struct file_dedupe_range {
+    __u64 src_offset;
+    __u64 src_length;
+    __u16 dest_count;
+    __u16 reserved1;
+    __u32 reserved2;
+    struct file_dedupe_range_info info[0];
+};
+.EE
+.in
+.P
+Deduplication is atomic with regards to concurrent writes, so no locks need to
+be taken to obtain a consistent deduplicated copy.
+.P
+The fields
+.IR reserved1 " and " reserved2
+must be zero.
+.P
+Destinations for the deduplication operation are conveyed in the array at the
+end of the structure.
+The number of destinations is given in
+.IR dest_count ,
+and the destination information is conveyed in the following form:
+.P
+.in +4n
+.EX
+struct file_dedupe_range_info {
+    __s64 dest_fd;
+    __u64 dest_offset;
+    __u64 bytes_deduped;
+    __s32 status;
+    __u32 reserved;
+};
+.EE
+.in
+.P
+Each deduplication operation targets
+.I src_length
+bytes in file descriptor
+.I dest_fd
+at offset
+.IR dest_offset .
+The field
+.I reserved
+must be zero.
+During the call,
+.I src_fd
+must be open for reading and
+.I dest_fd
+must be open for writing.
+The combined size of the struct
+.I file_dedupe_range
+and the struct
+.I file_dedupe_range_info
+array must not exceed the system page size.
+The maximum size of
+.I src_length
+is filesystem dependent and is typically 16\~MiB.
+This limit will be enforced silently by the filesystem.
+By convention, the storage used by
+.I src_fd
+is mapped into
+.I dest_fd
+and the previous contents in
+.I dest_fd
+are freed.
+.P
+Upon successful completion of this ioctl, the number of bytes successfully
+deduplicated is returned in
+.I bytes_deduped
+and a status code for the deduplication operation is returned in
+.IR status .
+If even a single byte in the range does not match, the deduplication
+operation request will be ignored and
+.I status
+set to
+.BR FILE_DEDUPE_RANGE_DIFFERS .
+The
+.I status
+code is set to
+.B FILE_DEDUPE_RANGE_SAME
+for success, a negative error code in case of error, or
+.B FILE_DEDUPE_RANGE_DIFFERS
+if the data did not match.
+.SH RETURN VALUE
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Possible errors include (but are not limited to) the following:
+.TP
+.B EBADF
+.I src_fd
+is not open for reading;
+.I dest_fd
+is not open for writing or is open for append-only writes; or the filesystem
+which
+.I src_fd
+resides on does not support deduplication.
+.TP
+.B EINVAL
+The filesystem does not support deduplicating the ranges of the given files.
+This error can also appear if either file descriptor represents
+a device, FIFO, or socket.
+Disk filesystems generally require the offset and length arguments
+to be aligned to the fundamental block size.
+Neither Btrfs nor XFS support
+overlapping deduplication ranges in the same file.
+.TP
+.B EISDIR
+One of the files is a directory and the filesystem does not support shared
+regions in directories.
+.TP
+.B ENOMEM
+The kernel was unable to allocate sufficient memory to perform the
+operation or
+.I dest_count
+is so large that the input argument description spans more than a single
+page of memory.
+.TP
+.B EOPNOTSUPP
+This can appear if the filesystem does not support deduplicating either file
+descriptor, or if either file descriptor refers to special inodes.
+.TP
+.B EPERM
+.I dest_fd
+is immutable.
+.TP
+.B ETXTBSY
+One of the files is a swap file.
+Swap files cannot share storage.
+.TP
+.B EXDEV
+.I dest_fd
+and
+.I src_fd
+are not on the same mounted filesystem.
+.SH VERSIONS
+Some filesystems may limit the amount of data that can be deduplicated in a
+single call.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 4.5.
+.P
+It was previously known as
+.B BTRFS_IOC_FILE_EXTENT_SAME
+and was private to Btrfs.
+.SH NOTES
+Because a copy-on-write operation requires the allocation of new storage, the
+.BR fallocate (2)
+operation may unshare shared blocks to guarantee that subsequent writes will
+not fail because of lack of disk space.
+.SH SEE ALSO
+.BR ioctl (2)
diff --git a/man/man2/ioctl_fslabel.2 b/man/man2/ioctl_fslabel.2
new file mode 100644
index 000000000..c4a211c4b
--- /dev/null
+++ b/man/man2/ioctl_fslabel.2
@@ -0,0 +1,72 @@
+.\" Copyright (c) 2018, Red Hat, Inc.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH ioctl_fslabel 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_fslabel \- get or set a filesystem label
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fs.h>" "       /* Definition of " *FSLABEL* " constants */"
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " fd ", FS_IOC_GETFSLABEL, char " label [FSLABEL_MAX]);
+.BI "int ioctl(int " fd ", FS_IOC_SETFSLABEL, char " label [FSLABEL_MAX]);
+.fi
+.SH DESCRIPTION
+If a filesystem supports online label manipulation, these
+.BR ioctl (2)
+operations can be used to get or set the filesystem label for the filesystem
+on which
+.I fd
+resides.
+The
+.B FS_IOC_SETFSLABEL
+operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+.SH RETURN VALUE
+On success zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Possible errors include (but are not limited to) the following:
+.TP
+.B EFAULT
+.I label
+references an inaccessible memory area.
+.TP
+.B EINVAL
+The specified label exceeds the maximum label length for the filesystem.
+.TP
+.B ENOTTY
+This can appear if the filesystem does not support online label manipulation.
+.TP
+.B EPERM
+The calling process does not have sufficient permissions to set the label.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 4.18.
+.P
+They were previously known as
+.B BTRFS_IOC_GET_FSLABEL
+and
+.B BTRFS_IOC_SET_FSLABEL
+and were private to Btrfs.
+.SH NOTES
+The maximum string length for this interface is
+.BR FSLABEL_MAX ,
+including the terminating null byte (\[aq]\\0\[aq]).
+Filesystems have differing maximum label lengths, which may or
+may not include the terminating null.
+The string provided to
+.B FS_IOC_SETFSLABEL
+must always be null-terminated, and the string returned by
+.B FS_IOC_GETFSLABEL
+will always be null-terminated.
+.SH SEE ALSO
+.BR ioctl (2),
+.BR blkid (8)
diff --git a/man/man2/ioctl_getfsmap.2 b/man/man2/ioctl_getfsmap.2
new file mode 100644
index 000000000..fa9d91894
--- /dev/null
+++ b/man/man2/ioctl_getfsmap.2
@@ -0,0 +1,351 @@
+.\" Copyright (c) 2017, Oracle.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH ioctl_getfsmap 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_getfsmap \- retrieve the physical layout of the filesystem
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fsmap.h>  " "/* Definition of " FS_IOC_GETFSMAP ,
+.BR "                             FM?_OF_*" ", and " *FMR_OWN_* " constants */"
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " fd ", FS_IOC_GETFSMAP, struct fsmap_head * " arg );
+.fi
+.SH DESCRIPTION
+This
+.BR ioctl (2)
+operation retrieves physical extent mappings for a filesystem.
+This information can be used to discover which files are mapped to a physical
+block, examine free space, or find known bad blocks, among other things.
+.P
+The sole argument to this operation should be a pointer to a single
+.IR "struct fsmap_head" ":"
+.P
+.in +4n
+.EX
+struct fsmap {
+    __u32 fmr_device;      /* Device ID */
+    __u32 fmr_flags;       /* Mapping flags */
+    __u64 fmr_physical;    /* Device offset of segment */
+    __u64 fmr_owner;       /* Owner ID */
+    __u64 fmr_offset;      /* File offset of segment */
+    __u64 fmr_length;      /* Length of segment */
+    __u64 fmr_reserved[3]; /* Must be zero */
+};
+\&
+struct fsmap_head {
+    __u32 fmh_iflags;       /* Control flags */
+    __u32 fmh_oflags;       /* Output flags */
+    __u32 fmh_count;        /* # of entries in array incl. input */
+    __u32 fmh_entries;      /* # of entries filled in (output) */
+    __u64 fmh_reserved[6];  /* Must be zero */
+\&
+    struct fsmap fmh_keys[2];  /* Low and high keys for
+                                  the mapping search */
+    struct fsmap fmh_recs[];   /* Returned records */
+};
+.EE
+.in
+.P
+The two
+.I fmh_keys
+array elements specify the lowest and highest reverse-mapping
+key for which the application would like physical mapping
+information.
+A reverse mapping key consists of the tuple (device, block, owner, offset).
+The owner and offset fields are part of the key because some filesystems
+support sharing physical blocks between multiple files and
+therefore may return multiple mappings for a given physical block.
+.P
+Filesystem mappings are copied into the
+.I fmh_recs
+array, which immediately follows the header data.
+.\"
+.SS Fields of struct fsmap_head
+The
+.I fmh_iflags
+field is a bit mask passed to the kernel to alter the output.
+No flags are currently defined, so the caller must set this value to zero.
+.P
+The
+.I fmh_oflags
+field is a bit mask of flags set by the kernel concerning the returned mappings.
+If
+.B FMH_OF_DEV_T
+is set, then the
+.I fmr_device
+field represents a
+.I dev_t
+structure containing the major and minor numbers of the block device.
+.P
+The
+.I fmh_count
+field contains the number of elements in the array being passed to the
+kernel.
+If this value is 0,
+.I fmh_entries
+will be set to the number of records that would have been returned had
+the array been large enough;
+no mapping information will be returned.
+.P
+The
+.I fmh_entries
+field contains the number of elements in the
+.I fmh_recs
+array that contain useful information.
+.P
+The
+.I fmh_reserved
+fields must be set to zero.
+.\"
+.SS Keys
+The two key records in
+.I fsmap_head.fmh_keys
+specify the lowest and highest extent records in the keyspace that the caller
+wants returned.
+A filesystem that can share blocks between files likely requires the tuple
+.RI "(" "device" ", " "physical" ", " "owner" ", " "offset" ", " "flags" ")"
+to uniquely index any filesystem mapping record.
+Classic non-sharing filesystems might be able to identify any record with only
+.RI "(" "device" ", " "physical" ", " "flags" ")."
+For example, if the low key is set to (8:0, 36864, 0, 0, 0), the filesystem will
+only return records for extents starting at or above 36\ KiB on disk.
+If the high key is set to (8:0, 1048576, 0, 0, 0),
+only records below 1\ MiB will be returned.
+The format of
+.I fmr_device
+in the keys must match the format of the same field in the output records,
+as defined below.
+By convention, the field
+.I fsmap_head.fmh_keys[0]
+must contain the low key and
+.I fsmap_head.fmh_keys[1]
+must contain the high key for the operation.
+.P
+For convenience, if
+.I fmr_length
+is set in the low key, it will be added to
+.IR fmr_block " or " fmr_offset
+as appropriate.
+The caller can take advantage of this subtlety to set up subsequent calls
+by copying
+.I fsmap_head.fmh_recs[fsmap_head.fmh_entries \- 1]
+into the low key.
+The function
+.I fsmap_advance
+(defined in
+.IR linux/fsmap.h )
+provides this functionality.
+.\"
+.SS Fields of struct fsmap
+The
+.I fmr_device
+field uniquely identifies the underlying storage device.
+If the
+.B FMH_OF_DEV_T
+flag is set in the header's
+.I fmh_oflags
+field, this field contains a
+.I dev_t
+from which major and minor numbers can be extracted.
+If the flag is not set, this field contains a value that must be unique
+for each unique storage device.
+.P
+The
+.I fmr_physical
+field contains the disk address of the extent in bytes.
+.P
+The
+.I fmr_owner
+field contains the owner of the extent.
+This is an inode number unless
+.B FMR_OF_SPECIAL_OWNER
+is set in the
+.I fmr_flags
+field, in which case the value is determined by the filesystem.
+See the section below about owner values for more details.
+.P
+The
+.I fmr_offset
+field contains the logical address in the mapping record in bytes.
+This field has no meaning if the
+.BR FMR_OF_SPECIAL_OWNER " or " FMR_OF_EXTENT_MAP
+flags are set in
+.IR fmr_flags "."
+.P
+The
+.I fmr_length
+field contains the length of the extent in bytes.
+.P
+The
+.I fmr_flags
+field is a bit mask of extent state flags.
+The bits are:
+.RS 0.4i
+.TP
+.B FMR_OF_PREALLOC
+The extent is allocated but not yet written.
+.TP
+.B FMR_OF_ATTR_FORK
+This extent contains extended attribute data.
+.TP
+.B FMR_OF_EXTENT_MAP
+This extent contains extent map information for the owner.
+.TP
+.B FMR_OF_SHARED
+Parts of this extent may be shared.
+.TP
+.B FMR_OF_SPECIAL_OWNER
+The
+.I fmr_owner
+field contains a special value instead of an inode number.
+.TP
+.B FMR_OF_LAST
+This is the last record in the data set.
+.RE
+.P
+The
+.I fmr_reserved
+field will be set to zero.
+.\"
+.SS Owner values
+Generally, the value of the
+.I fmr_owner
+field for non-metadata extents should be an inode number.
+However, filesystems are under no obligation to report inode numbers;
+they may instead report
+.B FMR_OWN_UNKNOWN
+if the inode number cannot easily be retrieved, if the caller lacks
+sufficient privilege, if the filesystem does not support stable
+inode numbers, or for any other reason.
+If a filesystem wishes to condition the reporting of inode numbers based
+on process capabilities, it is strongly urged that the
+.B CAP_SYS_ADMIN
+capability be used for this purpose.
+.TP
+The following special owner values are generic to all filesystems:
+.RS 0.4i
+.TP
+.B FMR_OWN_FREE
+Free space.
+.TP
+.B FMR_OWN_UNKNOWN
+This extent is in use but its owner is not known or not easily retrieved.
+.TP
+.B FMR_OWN_METADATA
+This extent is filesystem metadata.
+.RE
+.P
+XFS can return the following special owner values:
+.RS 0.4i
+.TP
+.B XFS_FMR_OWN_FREE
+Free space.
+.TP
+.B XFS_FMR_OWN_UNKNOWN
+This extent is in use but its owner is not known or not easily retrieved.
+.TP
+.B XFS_FMR_OWN_FS
+Static filesystem metadata which exists at a fixed address.
+These are the AG superblock, the AGF, the AGFL, and the AGI headers.
+.TP
+.B XFS_FMR_OWN_LOG
+The filesystem journal.
+.TP
+.B XFS_FMR_OWN_AG
+Allocation group metadata, such as the free space btrees and the
+reverse mapping btrees.
+.TP
+.B XFS_FMR_OWN_INOBT
+The inode and free inode btrees.
+.TP
+.B XFS_FMR_OWN_INODES
+Inode records.
+.TP
+.B XFS_FMR_OWN_REFC
+Reference count information.
+.TP
+.B XFS_FMR_OWN_COW
+This extent is being used to stage a copy-on-write.
+.TP
+.B XFS_FMR_OWN_DEFECTIVE:
+This extent has been marked defective either by the filesystem or the
+underlying device.
+.RE
+.P
+ext4 can return the following special owner values:
+.RS 0.4i
+.TP
+.B EXT4_FMR_OWN_FREE
+Free space.
+.TP
+.B EXT4_FMR_OWN_UNKNOWN
+This extent is in use but its owner is not known or not easily retrieved.
+.TP
+.B EXT4_FMR_OWN_FS
+Static filesystem metadata which exists at a fixed address.
+This is the superblock and the group descriptors.
+.TP
+.B EXT4_FMR_OWN_LOG
+The filesystem journal.
+.TP
+.B EXT4_FMR_OWN_INODES
+Inode records.
+.TP
+.B EXT4_FMR_OWN_BLKBM
+Block bit map.
+.TP
+.B EXT4_FMR_OWN_INOBM
+Inode bit map.
+.RE
+.SH RETURN VALUE
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The error placed in
+.I errno
+can be one of, but is not limited to, the following:
+.TP
+.B EBADF
+.I fd
+is not open for reading.
+.TP
+.B EBADMSG
+The filesystem has detected a checksum error in the metadata.
+.TP
+.B EFAULT
+The pointer passed in was not mapped to a valid memory address.
+.TP
+.B EINVAL
+The array is not long enough, the keys do not point to a valid part of
+the filesystem, the low key points to a higher point in the filesystem's
+physical storage address space than the high key, or a nonzero value
+was passed in one of the fields that must be zero.
+.TP
+.B ENOMEM
+Insufficient memory to process the operation.
+.TP
+.B EOPNOTSUPP
+The filesystem does not support this operation.
+.TP
+.B EUCLEAN
+The filesystem metadata is corrupt and needs repair.
+.SH STANDARDS
+Linux.
+.P
+Not all filesystems support it.
+.SH HISTORY
+Linux 4.12.
+.SH EXAMPLES
+See
+.I io/fsmap.c
+in the
+.I xfsprogs
+distribution for a sample program.
+.SH SEE ALSO
+.BR ioctl (2)
diff --git a/man/man2/ioctl_iflags.2 b/man/man2/ioctl_iflags.2
new file mode 100644
index 000000000..0f4c533bc
--- /dev/null
+++ b/man/man2/ioctl_iflags.2
@@ -0,0 +1,202 @@
+.\" Copyright (c) 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH ioctl_iflags 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_iflags \- ioctl() operations for inode flags
+.SH DESCRIPTION
+Various Linux filesystems support the notion of
+.IR "inode flags" \[em]attributes
+that modify the semantics of files and directories.
+These flags can be retrieved and modified using two
+.BR ioctl (2)
+operations:
+.P
+.in +4n
+.EX
+int attr;
+fd = open("pathname", ...);
+\&
+ioctl(fd, FS_IOC_GETFLAGS, &attr);  /* Place current flags
+                                       in \[aq]attr\[aq] */
+attr |= FS_NOATIME_FL;              /* Tweak returned bit mask */
+ioctl(fd, FS_IOC_SETFLAGS, &attr);  /* Update flags for inode
+                                       referred to by \[aq]fd\[aq] */
+.EE
+.in
+.P
+The
+.BR lsattr (1)
+and
+.BR chattr (1)
+shell commands provide interfaces to these two operations,
+allowing a user to view and modify the inode flags associated with a file.
+.P
+The following flags are supported
+(shown along with the corresponding letter used to indicate the flag by
+.BR lsattr (1)
+and
+.BR chattr (1)):
+.TP
+.BR FS_APPEND_FL " \[aq]a\[aq]"
+The file can be opened only with the
+.B O_APPEND
+flag.
+(This restriction applies even to the superuser.)
+Only a privileged process
+.RB ( CAP_LINUX_IMMUTABLE )
+can set or clear this attribute.
+.TP
+.BR FS_COMPR_FL " \[aq]c\[aq]"
+Store the file in a compressed format on disk.
+This flag is
+.I not
+supported by most of the mainstream filesystem implementations;
+one exception is
+.BR btrfs (5).
+.TP
+.BR FS_DIRSYNC_FL " \[aq]D\[aq] (since Linux 2.6.0)"
+Write directory changes synchronously to disk.
+This flag provides semantics equivalent to the
+.BR mount  (2)
+.B MS_DIRSYNC
+option, but on a per-directory basis.
+This flag can be applied only to directories.
+.\" .TP
+.\" .BR FS_EXTENT_FL " \[aq]e\[aq]"
+.\" FIXME Some support on ext4? (EXT4_EXTENTS_FL)
+.TP
+.BR FS_IMMUTABLE_FL " \[aq]i\[aq]"
+The file is immutable:
+no changes are permitted to the file contents or metadata
+(permissions, timestamps, ownership, link count, and so on).
+(This restriction applies even to the superuser.)
+Only a privileged process
+.RB ( CAP_LINUX_IMMUTABLE )
+can set or clear this attribute.
+.TP
+.BR FS_JOURNAL_DATA_FL " \[aq]j\[aq]"
+Enable journaling of file data on
+.BR ext3 (5)
+and
+.BR ext4 (5)
+filesystems.
+On a filesystem that is journaling in
+.I ordered
+or
+.I writeback
+mode, a privileged
+.RB ( CAP_SYS_RESOURCE )
+process can set this flag to enable journaling of data updates on
+a per-file basis.
+.TP
+.BR FS_NOATIME_FL " \[aq]A\[aq]"
+Don't update the file last access time when the file is accessed.
+This can provide I/O performance benefits for applications that do not care
+about the accuracy of this timestamp.
+This flag provides functionality similar to the
+.BR mount (2)
+.B MS_NOATIME
+flag, but on a per-file basis.
+.\" .TP
+.\" .BR FS_NOCOMP_FL " \[aq]\[aq]"
+.\" FIXME Support for FS_NOCOMP_FL on Btrfs?
+.TP
+.BR FS_NOCOW_FL " \[aq]C\[aq] (since Linux 2.6.39)"
+The file will not be subject to copy-on-write updates.
+This flag has an effect only on filesystems that support copy-on-write
+semantics, such as Btrfs.
+See
+.BR chattr (1)
+and
+.BR btrfs (5).
+.TP
+.BR FS_NODUMP_FL " \[aq]d\[aq]"
+Don't include this file in backups made using
+.BR dump (8).
+.TP
+.BR FS_NOTAIL_FL " \[aq]t\[aq]"
+This flag is supported only on Reiserfs.
+It disables the Reiserfs tail-packing feature,
+which tries to pack small files (and the final fragment of larger files)
+into the same disk block as the file metadata.
+.TP
+.BR FS_PROJINHERIT_FL " \[aq]P\[aq] (since Linux 4.5)"
+.\" commit 040cb3786d9b25293b8b0b05b90da0f871e1eb9b
+.\" Flag name was added in Linux 4.4
+.\" FIXME Not currently supported because not in FS_FL_USER_MODIFIABLE?
+Inherit the quota project ID.
+Files and subdirectories will inherit the project ID of the directory.
+This flag can be applied only to directories.
+.TP
+.BR FS_SECRM_FL " \[aq]s\[aq]"
+Mark the file for secure deletion.
+This feature is not implemented by any filesystem,
+since the task of securely erasing a file from a recording medium
+is surprisingly difficult.
+.TP
+.BR FS_SYNC_FL " \[aq]S\[aq]"
+Make file updates synchronous.
+For files, this makes all writes synchronous
+(as though all opens of the file were with the
+.B O_SYNC
+flag).
+For directories, this has the same effect as the
+.B FS_DIRSYNC_FL
+flag.
+.TP
+.BR FS_TOPDIR_FL " \[aq]T\[aq]"
+Mark a directory for special treatment under the Orlov block-allocation
+strategy.
+See
+.BR chattr (1)
+for details.
+This flag can be applied only to directories and
+has an effect only for ext2, ext3, and ext4.
+.TP
+.BR FS_UNRM_FL " \[aq]u\[aq]"
+Allow the file to be undeleted if it is deleted.
+This feature is not implemented by any filesystem,
+since it is possible to implement file-recovery mechanisms outside the kernel.
+.P
+In most cases,
+when any of the above flags is set on a directory,
+the flag is inherited by files and subdirectories
+created inside that directory.
+Exceptions include
+.BR FS_TOPDIR_FL ,
+which is not inheritable, and
+.BR FS_DIRSYNC_FL ,
+which is inherited only by subdirectories.
+.SH STANDARDS
+Linux.
+.SH NOTES
+In order to change the inode flags of a file using the
+.B FS_IOC_SETFLAGS
+operation,
+the effective user ID of the caller must match the owner of the file,
+or the caller must have the
+.B CAP_FOWNER
+capability.
+.P
+The type of the argument given to the
+.B FS_IOC_GETFLAGS
+and
+.B FS_IOC_SETFLAGS
+operations is
+.IR int\~* ,
+notwithstanding the implication in the kernel source file
+.I include/uapi/linux/fs.h
+that the argument is
+.IR long\~* .
+.SH SEE ALSO
+.BR chattr (1),
+.BR lsattr (1),
+.BR mount (2),
+.BR btrfs (5),
+.BR ext4 (5),
+.BR xfs (5),
+.BR xattr (7),
+.BR mount (8)
diff --git a/man/man2/ioctl_ns.2 b/man/man2/ioctl_ns.2
new file mode 100644
index 000000000..958a686b0
--- /dev/null
+++ b/man/man2/ioctl_ns.2
@@ -0,0 +1,342 @@
+.\" Copyright (c) 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH ioctl_ns 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_ns \- ioctl() operations for Linux namespaces
+.SH DESCRIPTION
+.\" ============================================================
+.\"
+.SS Discovering namespace relationships
+The following
+.BR ioctl (2)
+operations are provided to allow discovery of namespace relationships (see
+.BR user_namespaces (7)
+and
+.BR pid_namespaces (7)).
+The form of the calls is:
+.P
+.in +4n
+.EX
+new_fd = ioctl(fd, op);
+.EE
+.in
+.P
+In each case,
+.I fd
+refers to a
+.IR /proc/ pid /ns/*
+file.
+Both operations return a new file descriptor on success.
+.TP
+.BR NS_GET_USERNS " (since Linux 4.9)"
+.\" commit bcac25a58bfc6bd79191ac5d7afb49bea96da8c9
+.\" commit 6786741dbf99e44fb0c0ed85a37582b8a26f1c3b
+Returns a file descriptor that refers to the owning user namespace
+for the namespace referred to by
+.IR fd .
+.TP
+.BR NS_GET_PARENT " (since Linux 4.9)"
+.\" commit a7306ed8d94af729ecef8b6e37506a1c6fc14788
+Returns a file descriptor that refers to the parent namespace of
+the namespace referred to by
+.IR fd .
+This operation is valid only for hierarchical namespaces
+(i.e., PID and user namespaces).
+For user namespaces,
+.B NS_GET_PARENT
+is synonymous with
+.BR NS_GET_USERNS .
+.P
+The new file descriptor returned by these operations is opened with the
+.B O_RDONLY
+and
+.B O_CLOEXEC
+(close-on-exec; see
+.BR fcntl (2))
+flags.
+.P
+By applying
+.BR fstat (2)
+to the returned file descriptor, one obtains a
+.I stat
+structure whose
+.I st_dev
+(resident device) and
+.I st_ino
+(inode number) fields together identify the owning/parent namespace.
+This inode number can be matched with the inode number of another
+.IR /proc/ pid /ns/ { pid , user }
+file to determine whether that is the owning/parent namespace.
+.P
+Either of these
+.BR ioctl (2)
+operations can fail with the following errors:
+.TP
+.B EPERM
+The requested namespace is outside of the caller's namespace scope.
+This error can occur if, for example, the owning user namespace is an
+ancestor of the caller's current user namespace.
+It can also occur on attempts to obtain the parent of the initial
+user or PID namespace.
+.TP
+.B ENOTTY
+The operation is not supported by this kernel version.
+.P
+Additionally, the
+.B NS_GET_PARENT
+operation can fail with the following error:
+.TP
+.B EINVAL
+.I fd
+refers to a nonhierarchical namespace.
+.P
+See the EXAMPLES section for an example of the use of these operations.
+.\" ============================================================
+.\"
+.SS Discovering the namespace type
+The
+.B NS_GET_NSTYPE
+.\" commit e5ff5ce6e20ee22511398bb31fb912466cf82a36
+operation (available since Linux 4.11) can be used to discover
+the type of namespace referred to by the file descriptor
+.IR fd :
+.P
+.in +4n
+.EX
+nstype = ioctl(fd, NS_GET_NSTYPE);
+.EE
+.in
+.P
+.I fd
+refers to a
+.IR /proc/ pid /ns/*
+file.
+.P
+The return value is one of the
+.B CLONE_NEW*
+values that can be specified to
+.BR clone (2)
+or
+.BR unshare (2)
+in order to create a namespace.
+.\" ============================================================
+.\"
+.SS Discovering the owner of a user namespace
+The
+.B NS_GET_OWNER_UID
+.\" commit 015bb305b8ebe8d601a238ab70ebdc394c7a19ba
+operation (available since Linux 4.11) can be used to discover
+the owner user ID of a user namespace (i.e., the effective user ID
+of the process that created the user namespace).
+The form of the call is:
+.P
+.in +4n
+.EX
+uid_t uid;
+ioctl(fd, NS_GET_OWNER_UID, &uid);
+.EE
+.in
+.P
+.I fd
+refers to a
+.IR /proc/ pid /ns/user
+file.
+.P
+The owner user ID is returned in the
+.I uid_t
+pointed to by the third argument.
+.P
+This operation can fail with the following error:
+.TP
+.B EINVAL
+.I fd
+does not refer to a user namespace.
+.SH ERRORS
+Any of the above
+.BR ioctl ()
+operations can return the following errors:
+.TP
+.B ENOTTY
+.I fd
+does not refer to a
+.IR /proc/ pid /ns/ *
+file.
+.SH STANDARDS
+Linux.
+.SH EXAMPLES
+The example shown below uses the
+.BR ioctl (2)
+operations described above to perform simple
+discovery of namespace relationships.
+The following shell sessions show various examples of the use
+of this program.
+.P
+Trying to get the parent of the initial user namespace fails,
+since it has no parent:
+.P
+.in +4n
+.EX
+$ \fB./ns_show /proc/self/ns/user p\fP
+The parent namespace is outside your namespace scope
+.EE
+.in
+.P
+Create a process running
+.BR sleep (1)
+that resides in new user and UTS namespaces,
+and show that the new UTS namespace is associated with the new user namespace:
+.P
+.in +4n
+.EX
+$ \fBunshare \-Uu sleep 1000 &\fP
+[1] 23235
+$ \fB./ns_show /proc/23235/ns/uts u\fP
+Device/Inode of owning user namespace is: [0,3] / 4026532448
+$ \fBreadlink /proc/23235/ns/user\fP
+user:[4026532448]
+.EE
+.in
+.P
+Then show that the parent of the new user namespace in the preceding
+example is the initial user namespace:
+.P
+.in +4n
+.EX
+$ \fBreadlink /proc/self/ns/user\fP
+user:[4026531837]
+$ \fB./ns_show /proc/23235/ns/user p\fP
+Device/Inode of parent namespace is: [0,3] / 4026531837
+.EE
+.in
+.P
+Start a shell in a new user namespace, and show that from within
+this shell, the parent user namespace can't be discovered.
+Similarly, the UTS namespace
+(which is associated with the initial user namespace)
+can't be discovered.
+.P
+.in +4n
+.EX
+$ \fBPS1="sh2$ " unshare \-U bash\fP
+sh2$ \fB./ns_show /proc/self/ns/user p\fP
+The parent namespace is outside your namespace scope
+sh2$ \fB./ns_show /proc/self/ns/uts u\fP
+The owning user namespace is outside your namespace scope
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (ns_show.c)
+.EX
+/* ns_show.c
+\&
+   Licensed under the GNU General Public License v2 or later.
+*/
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/nsfs.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int          fd, userns_fd, parent_fd;
+    struct stat  sb;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s /proc/[pid]/ns/[file] [p|u]\en",
+                argv[0]);
+        fprintf(stderr, "\enDisplay the result of one or both "
+                "of NS_GET_USERNS (u) or NS_GET_PARENT (p)\en"
+                "for the specified /proc/[pid]/ns/[file]. If neither "
+                "\[aq]p\[aq] nor \[aq]u\[aq] is specified,\en"
+                "NS_GET_USERNS is the default.\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Obtain a file descriptor for the \[aq]ns\[aq] file specified
+       in argv[1]. */
+\&
+    fd = open(argv[1], O_RDONLY);
+    if (fd == \-1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Obtain a file descriptor for the owning user namespace and
+       then obtain and display the inode number of that namespace. */
+\&
+    if (argc < 3 || strchr(argv[2], \[aq]u\[aq])) {
+        userns_fd = ioctl(fd, NS_GET_USERNS);
+\&
+        if (userns_fd == \-1) {
+            if (errno == EPERM)
+                printf("The owning user namespace is outside "
+                       "your namespace scope\en");
+            else
+               perror("ioctl\-NS_GET_USERNS");
+            exit(EXIT_FAILURE);
+         }
+\&
+        if (fstat(userns_fd, &sb) == \-1) {
+            perror("fstat\-userns");
+            exit(EXIT_FAILURE);
+        }
+        printf("Device/Inode of owning user namespace is: "
+               "[%x,%x] / %ju\en",
+               major(sb.st_dev),
+               minor(sb.st_dev),
+               (uintmax_t) sb.st_ino);
+\&
+        close(userns_fd);
+    }
+\&
+    /* Obtain a file descriptor for the parent namespace and
+       then obtain and display the inode number of that namespace. */
+\&
+    if (argc > 2 && strchr(argv[2], \[aq]p\[aq])) {
+        parent_fd = ioctl(fd, NS_GET_PARENT);
+\&
+        if (parent_fd == \-1) {
+            if (errno == EINVAL)
+                printf("Can\[aq] get parent namespace of a "
+                       "nonhierarchical namespace\en");
+            else if (errno == EPERM)
+                printf("The parent namespace is outside "
+                       "your namespace scope\en");
+            else
+                perror("ioctl\-NS_GET_PARENT");
+            exit(EXIT_FAILURE);
+        }
+\&
+        if (fstat(parent_fd, &sb) == \-1) {
+            perror("fstat\-parentns");
+            exit(EXIT_FAILURE);
+        }
+        printf("Device/Inode of parent namespace is: [%x,%x] / %ju\en",
+               major(sb.st_dev),
+               minor(sb.st_dev),
+               (uintmax_t) sb.st_ino);
+\&
+        close(parent_fd);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fstat (2),
+.BR ioctl (2),
+.BR proc (5),
+.BR namespaces (7)
diff --git a/man/man2/ioctl_pagemap_scan.2 b/man/man2/ioctl_pagemap_scan.2
new file mode 100644
index 000000000..f7235b8be
--- /dev/null
+++ b/man/man2/ioctl_pagemap_scan.2
@@ -0,0 +1,206 @@
+.\" This manpage is Copyright (C) 2023 Collabora;
+.\" Written by Muhammad Usama Anjum <usama.anjum@collabora.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH ioctl_pagemap_scan 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_pagemap_scan \- get and/or clear page flags
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fs.h>" "  /* Definition of " "struct pm_scan_arg" ,
+.BR "                          struct page_region" ", and " PAGE_IS_* " constants */"
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " pagemap_fd ", PAGEMAP_SCAN, struct pm_scan_arg *" arg );
+.fi
+.SH DESCRIPTION
+This
+.BR ioctl (2)
+is used to get and optionally clear some specific flags from page table entries.
+The information is returned with
+.B PAGE_SIZE
+granularity.
+.P
+To start tracking the written state (flag) of a page or range of memory,
+the
+.B UFFD_FEATURE_WP_ASYNC
+must be enabled by
+.B UFFDIO_API
+.BR ioctl (2)
+on
+.B userfaultfd
+and memory range must be registered with
+.B UFFDIO_REGISTER
+.BR ioctl (2)
+in
+.B UFFDIO_REGISTER_MODE_WP
+mode.
+.SS Supported page flags
+The following page table entry flags are supported:
+.TP
+.B PAGE_IS_WPALLOWED
+The page has asynchronous write-protection enabled.
+.TP
+.B PAGE_IS_WRITTEN
+The page has been written to from the time it was write protected.
+.TP
+.B PAGE_IS_FILE
+The page is file backed.
+.TP
+.B PAGE_IS_PRESENT
+The page is present in the memory.
+.TP
+.B PAGE_IS_SWAPPED
+The page is swapped.
+.TP
+.B PAGE_IS_PFNZERO
+The page has zero PFN.
+.TP
+.B PAGE_IS_HUGE
+The page is THP or Hugetlb backed.
+.SS Supported operations
+The get operation is always performed
+if the output buffer is specified.
+The other operations are as following:
+.TP
+.B PM_SCAN_WP_MATCHING
+Write protect the matched pages.
+.TP
+.B PM_SCAN_CHECK_WPASYNC
+Abort the scan
+when a page is found
+which doesn't have the Userfaultfd Asynchronous Write protection enabled.
+.SS The \f[I]struct pm_scan_arg\f[] argument
+.EX
+struct pm_scan_arg {
+    __u64  size;
+    __u64  flags;
+    __u64  start;
+    __u64  end;
+    __u64  walk_end;
+    __u64  vec;
+    __u64  vec_len;
+    __u64  max_pages
+    __u64  category_inverted;
+    __u64  category_mask;
+    __u64  category_anyof_mask
+    __u64  return_mask;
+};
+.EE
+.TP
+.B size
+This field should be set to the size of the structure in bytes,
+as in
+.IR sizeof(struct\~pm_scan_arg) .
+.TP
+.B flags
+The operations to be performed are specified in it.
+.TP
+.B start
+The starting address of the scan is specified in it.
+.TP
+.B end
+The ending address of the scan is specified in it.
+.TP
+.B walk_end
+The kernel returns the scan's ending address in it.
+The
+.I walk_end
+equal to
+.I end
+means that scan has completed on the entire range.
+.TP
+.B vec
+The address of
+.I page_region
+array for output.
+.IP
+.in +4n
+.EX
+struct page_region {
+    __u64  start;
+    __u64  end;
+    __u64  categories;
+};
+.EE
+.in
+.TP
+.B vec_len
+The length of the
+.I page_region
+struct array.
+.TP
+.B max_pages
+It is the optional limit for the number of output pages required.
+.TP
+.B category_inverted
+.BI PAGE_IS_ *
+categories which values match if 0 instead of 1.
+.TP
+.B category_mask
+Skip pages for which any
+.BI PAGE_IS_ *
+category doesn't match.
+.TP
+.B category_anyof_mask
+Skip pages for which no
+.BI PAGE_IS_ *
+category matches.
+.TP
+.B return_mask
+.BI PAGE_IS_ *
+categories that are to be reported in
+.IR page_region .
+.SH RETURN VALUE
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Error codes can be one of, but are not limited to, the following:
+.TP
+.B EINVAL
+Invalid arguments i.e.,
+invalid
+.I size
+of the argument,
+invalid
+.IR flags ,
+invalid
+.IR categories ,
+the
+.I start
+address isn't aligned with
+.BR PAGE_SIZE ,
+or
+.I vec_len
+is specified when
+.I vec
+is NULL.
+.TP
+.B EFAULT
+Invalid
+.I arg
+pointer,
+invalid
+.I vec
+pointer,
+or invalid address range specified by
+.I start
+and
+.IR end .
+.TP
+.B ENOMEM
+No memory is available.
+.TP
+.B EINTR
+Fetal signal is pending.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 6.7.
+.SH SEE ALSO
+.BR ioctl (2)
diff --git a/man/man2/ioctl_pipe.2 b/man/man2/ioctl_pipe.2
new file mode 100644
index 000000000..5f5c42652
--- /dev/null
+++ b/man/man2/ioctl_pipe.2
@@ -0,0 +1,64 @@
+.\" Copyright (c) 2022 by Cyril Hrubis <chrubi@suse.cz>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH ioctl_pipe 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_pipe \- ioctl() operations for General notification mechanism
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/watch_queue.h>" "  /* Definition of " IOC_WATCH_QUEUE_ "* */"
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " pipefd "[1], IOC_WATCH_QUEUE_SET_SIZE, int " size );
+.BI "int ioctl(int " pipefd "[1], IOC_WATCH_QUEUE_SET_FILTER,"
+.BI "          struct watch_notification_filter *" filter );
+.fi
+.SH DESCRIPTION
+The following
+.BR ioctl (2)
+operations are provided to set up general notification queue parameters.
+The notification queue is built on the top of a
+.BR pipe (2)
+opened with the
+.B O_NOTIFICATION_PIPE
+flag.
+.TP
+.BR IOC_WATCH_QUEUE_SET_SIZE " (since Linux 5.8)"
+.\" commit c73be61cede5882f9605a852414db559c0ebedfd
+Preallocates the pipe buffer memory so that
+it can fit
+.I size
+notification messages.
+Currently,
+.I size
+must be between 1 and 512.
+.TP
+.BR IOC_WATCH_QUEUE_SET_FILTER " (since Linux 5.8)"
+.\" commit c73be61cede5882f9605a852414db559c0ebedfd
+Watch queue filter can limit events that are received.
+Filters are passed in a
+.I struct watch_notification_filter
+and each filter is described by a
+.I struct watch_notification_type_filter
+structure.
+.IP
+.in +4n
+.EX
+struct watch_notification_filter {
+        __u32   nr_filters;
+        __u32   __reserved;
+        struct watch_notification_type_filter filters[];
+};
+\&
+struct watch_notification_type_filter {
+        __u32   type;
+        __u32   info_filter;
+        __u32   info_mask;
+        __u32   subtype_filter[8];
+};
+.EE
+.in
+.SH SEE ALSO
+.BR pipe (2),
+.BR ioctl (2)
diff --git a/man/man2/ioctl_tty.2 b/man/man2/ioctl_tty.2
new file mode 100644
index 000000000..c458933a2
--- /dev/null
+++ b/man/man2/ioctl_tty.2
@@ -0,0 +1,922 @@
+'\" t
+.\" Copyright 2002 Walter Harms <walter.harms@informatik.uni-oldenburg.de>
+.\" and Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH ioctl_tty 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_tty \- ioctls for terminals and serial lines
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/ioctl.h>
+.BR "#include <asm/termbits.h>" "   /* Definition of " "struct termios" ,
+.BR    "                               struct termios2" ", and"
+.BR    "                               Bnnn" ", " BOTHER ", " CBAUD ", " CLOCAL ,
+.BR    "                               TC*" { FLUSH , ON , OFF "} and other constants */"
+.P
+.BI "int ioctl(int " fd ", int " op ", ...);"
+.fi
+.SH DESCRIPTION
+The
+.BR ioctl (2)
+call for terminals and serial ports accepts many possible operation arguments.
+Most require a third argument, of varying type, here called
+.I argp
+or
+.IR arg .
+.P
+Use of
+.BR ioctl ()
+makes for nonportable programs.
+Use the POSIX interface described in
+.BR termios (3)
+whenever possible.
+.P
+Please note that
+.B struct termios
+from
+.I <asm/termbits.h>
+is different and incompatible with
+.B struct termios
+from
+.IR <termios.h> .
+These ioctl calls require
+.B struct termios
+from
+.IR <asm/termbits.h> .
+.SS Get and set terminal attributes
+.TP
+.B TCGETS
+Argument:
+.BI "struct termios\~*" argp
+.IP
+Equivalent to
+.IR "tcgetattr(fd, argp)" .
+.IP
+Get the current serial port settings.
+.TP
+.B TCSETS
+Argument:
+.BI "const struct termios\~*" argp
+.IP
+Equivalent to
+.IR "tcsetattr(fd, TCSANOW, argp)" .
+.IP
+Set the current serial port settings.
+.TP
+.B TCSETSW
+Argument:
+.BI "const struct termios\~*" argp
+.IP
+Equivalent to
+.IR "tcsetattr(fd, TCSADRAIN, argp)" .
+.IP
+Allow the output buffer to drain, and
+set the current serial port settings.
+.TP
+.B TCSETSF
+Argument:
+.BI "const struct termios\~*" argp
+.IP
+Equivalent to
+.IR "tcsetattr(fd, TCSAFLUSH, argp)" .
+.IP
+Allow the output buffer to drain, discard pending input, and
+set the current serial port settings.
+.P
+The following four ioctls, added in Linux 2.6.20,
+.\" commit 64bb6c5e1ddcd47c951740485026ef08975ee2e6
+.\" commit 592ee3a5e5e2a981ef2829a0380093006d045661
+are just like
+.BR TCGETS ,
+.BR TCSETS ,
+.BR TCSETSW ,
+.BR TCSETSF ,
+except that they take a
+.I "struct termios2\~*"
+instead of a
+.IR "struct termios\~*" .
+If the structure member
+.B c_cflag
+contains the flag
+.BR BOTHER ,
+then the baud rate is stored in the structure members
+.B c_ispeed
+and
+.B c_ospeed
+as integer values.
+These ioctls are not supported on all architectures.
+.RS
+.TS
+lb l.
+TCGETS2	\fBstruct termios2 *\fPargp
+TCSETS2	\fBconst struct termios2 *\fPargp
+TCSETSW2	\fBconst struct termios2 *\fPargp
+TCSETSF2	\fBconst struct termios2 *\fPargp
+.TE
+.RE
+.P
+The following four ioctls are just like
+.BR TCGETS ,
+.BR TCSETS ,
+.BR TCSETSW ,
+.BR TCSETSF ,
+except that they take a
+.I "struct termio\~*"
+instead of a
+.IR "struct termios\~*" .
+.RS
+.TS
+lb l.
+TCGETA	\fBstruct termio *\fPargp
+TCSETA	\fBconst struct termio *\fPargp
+TCSETAW	\fBconst struct termio *\fPargp
+TCSETAF	\fBconst struct termio *\fPargp
+.TE
+.RE
+.SS Locking the termios structure
+The
+.I termios
+structure of a terminal can be locked.
+The lock is itself a
+.I termios
+structure, with nonzero bits or fields indicating a
+locked value.
+.TP
+.B TIOCGLCKTRMIOS
+Argument:
+.BI "struct termios\~*" argp
+.IP
+Gets the locking status of the
+.I termios
+structure of the terminal.
+.TP
+.B TIOCSLCKTRMIOS
+Argument:
+.BI "const struct termios\~*" argp
+.IP
+Sets the locking status of the
+.I termios
+structure of the terminal.
+Only a process with the
+.B CAP_SYS_ADMIN
+capability can do this.
+.SS Get and set window size
+Window sizes are kept in the kernel, but not used by the kernel
+(except in the case of virtual consoles, where the kernel will
+update the window size when the size of the virtual console changes,
+for example, by loading a new font).
+.TP
+.B TIOCGWINSZ
+Argument:
+.BI "struct winsize\~*" argp
+.IP
+Get window size.
+.TP
+.B TIOCSWINSZ
+Argument:
+.BI "const struct winsize\~*" argp
+.IP
+Set window size.
+.P
+The struct used by these ioctls is defined as
+.P
+.in +4n
+.EX
+struct winsize {
+    unsigned short ws_row;
+    unsigned short ws_col;
+    unsigned short ws_xpixel;   /* unused */
+    unsigned short ws_ypixel;   /* unused */
+};
+.EE
+.in
+.P
+When the window size changes, a
+.B SIGWINCH
+signal is sent to the
+foreground process group.
+.SS Sending a break
+.TP
+.B TCSBRK
+Argument:
+.BI "int " arg
+.IP
+Equivalent to
+.IR "tcsendbreak(fd, arg)" .
+.IP
+If the terminal is using asynchronous serial data transmission, and
+.I arg
+is zero, then send a break (a stream of zero bits) for between
+0.25 and 0.5 seconds.
+If the terminal is not using asynchronous
+serial data transmission, then either a break is sent, or the function
+returns without doing anything.
+When
+.I arg
+is nonzero, nobody knows what will happen.
+.IP
+(SVr4, UnixWare, Solaris, and Linux treat
+.I "tcsendbreak(fd,arg)"
+with nonzero
+.I arg
+like
+.IR "tcdrain(fd)" .
+SunOS treats
+.I arg
+as a multiplier, and sends a stream of bits
+.I arg
+times as long as done for zero
+.IR arg .
+DG/UX and AIX treat
+.I arg
+(when nonzero) as a time interval measured in milliseconds.
+HP-UX ignores
+.IR arg .)
+.TP
+.B TCSBRKP
+Argument:
+.BI "int " arg
+.IP
+So-called "POSIX version" of
+.BR TCSBRK .
+It treats nonzero
+.I arg
+as a time interval measured in deciseconds, and does nothing
+when the driver does not support breaks.
+.TP
+.B TIOCSBRK
+Argument:
+.B void
+.IP
+Turn break on, that is, start sending zero bits.
+.TP
+.B TIOCCBRK
+Argument:
+.B void
+.IP
+Turn break off, that is, stop sending zero bits.
+.SS Software flow control
+.TP
+.B TCXONC
+Argument:
+.BI "int " arg
+.IP
+Equivalent to
+.IR "tcflow(fd, arg)" .
+.IP
+See
+.BR tcflow (3)
+for the argument values
+.BR TCOOFF ,
+.BR TCOON ,
+.BR TCIOFF ,
+.BR TCION .
+.SS Buffer count and flushing
+.TP
+.B FIONREAD
+Argument:
+.BI "int\~*" argp
+.IP
+Get the number of bytes in the input buffer.
+.TP
+.B TIOCINQ
+Argument:
+.BI "int\~*" argp
+.IP
+Same as
+.BR FIONREAD .
+.TP
+.B TIOCOUTQ
+Argument:
+.BI "int\~*" argp
+.IP
+Get the number of bytes in the output buffer.
+.TP
+.B TCFLSH
+Argument:
+.BI "int " arg
+.IP
+Equivalent to
+.IR "tcflush(fd, arg)" .
+.IP
+See
+.BR tcflush (3)
+for the argument values
+.BR TCIFLUSH ,
+.BR TCOFLUSH ,
+.BR TCIOFLUSH .
+.TP
+.B TIOCSERGETLSR
+Argument:
+.BI "int\~*" argp
+.IP
+Get line status register.
+Status register has
+.B TIOCSER_TEMT
+bit set when
+output buffer is empty and also hardware transmitter is physically empty.
+.IP
+Does not have to be supported by all serial tty drivers.
+.IP
+.BR tcdrain (3)
+does not wait and returns immediately when
+.B TIOCSER_TEMT
+bit is set.
+.SS Faking input
+.TP
+.B TIOCSTI
+Argument:
+.BI "const char\~*" argp
+.IP
+Insert the given byte in the input queue.
+.IP
+Since Linux 6.2,
+.\" commit 690c8b804ad2eafbd35da5d3c95ad325ca7d5061
+.\" commit 83efeeeb3d04b22aaed1df99bc70a48fe9d22c4d
+this operation may require the
+.B CAP_SYS_ADMIN
+capability (if the
+.I dev.tty.legacy_tiocsti
+sysctl variable is set to false).
+.SS Redirecting console output
+.TP
+.B TIOCCONS
+Argument:
+.B void
+.IP
+Redirect output that would have gone to
+.I /dev/console
+or
+.I /dev/tty0
+to the given terminal.
+If that was a pseudoterminal master, send it to the slave.
+Before Linux 2.6.10,
+anybody can do this as long as the output was not redirected yet;
+since Linux 2.6.10, only a process with the
+.B CAP_SYS_ADMIN
+capability may do this.
+If output was redirected already, then
+.B EBUSY
+is returned,
+but redirection can be stopped by using this ioctl with
+.I fd
+pointing at
+.I /dev/console
+or
+.IR /dev/tty0 .
+.SS Controlling terminal
+.TP
+.B TIOCSCTTY
+Argument:
+.BI "int " arg
+.IP
+Make the given terminal the controlling terminal of the calling process.
+The calling process must be a session leader and not have a
+controlling terminal already.
+For this case,
+.I arg
+should be specified as zero.
+.IP
+If this terminal is already the controlling terminal
+of a different session group, then the ioctl fails with
+.BR EPERM ,
+unless the caller has the
+.B CAP_SYS_ADMIN
+capability and
+.I arg
+equals 1, in which case the terminal is stolen, and all processes that had
+it as controlling terminal lose it.
+.TP
+.B TIOCNOTTY
+Argument:
+.B void
+.IP
+If the given terminal was the controlling terminal of the calling process,
+give up this controlling terminal.
+If the process was session leader,
+then send
+.B SIGHUP
+and
+.B SIGCONT
+to the foreground process group
+and all processes in the current session lose their controlling terminal.
+.SS Process group and session ID
+.TP
+.B TIOCGPGRP
+Argument:
+.BI "pid_t\~*" argp
+.IP
+When successful, equivalent to
+.IR "*argp = tcgetpgrp(fd)" .
+.IP
+Get the process group ID of the foreground process group on this terminal.
+.TP
+.B TIOCSPGRP
+Argument:
+.BI "const pid_t\~*" argp
+.IP
+Equivalent to
+.IR "tcsetpgrp(fd, *argp)" .
+.IP
+Set the foreground process group ID of this terminal.
+.TP
+.B TIOCGSID
+Argument:
+.BI "pid_t\~*" argp
+.IP
+When successful, equivalent to
+.IR "*argp = tcgetsid(fd)" .
+.IP
+Get the session ID of the given terminal.
+This fails with the error
+.B ENOTTY
+if the terminal is not a master pseudoterminal
+and not our controlling terminal.
+Strange.
+.SS Exclusive mode
+.TP
+.B TIOCEXCL
+Argument:
+.B void
+.IP
+Put the terminal into exclusive mode.
+No further
+.BR open (2)
+operations on the terminal are permitted.
+(They fail with
+.BR EBUSY ,
+except for a process with the
+.B CAP_SYS_ADMIN
+capability.)
+.TP
+.B TIOCGEXCL
+Argument:
+.BI "int\~*" argp
+.IP
+(since Linux 3.8)
+If the terminal is currently in exclusive mode,
+place a nonzero value in the location pointed to by
+.IR argp ;
+otherwise, place zero in
+.IR *argp .
+.TP
+.B TIOCNXCL
+Argument:
+.B void
+.IP
+Disable exclusive mode.
+.SS Line discipline
+.TP
+.B TIOCGETD
+Argument:
+.BI "int\~*" argp
+.IP
+Get the line discipline of the terminal.
+.TP
+.B TIOCSETD
+Argument:
+.BI "const int\~*" argp
+.IP
+Set the line discipline of the terminal.
+.SS Pseudoterminal ioctls
+.TP
+.B TIOCPKT
+Argument:
+.BI "const int\~*" argp
+.IP
+Enable (when
+.RI * argp
+is nonzero) or disable packet mode.
+Can be applied to the master side of a pseudoterminal only (and will return
+.B ENOTTY
+otherwise).
+In packet mode, each subsequent
+.BR read (2)
+will return a packet that either contains a single nonzero control byte,
+or has a single byte containing zero (\[aq]\e0\[aq]) followed by data
+written on the slave side of the pseudoterminal.
+If the first byte is not
+.B TIOCPKT_DATA
+(0), it is an OR of one
+or more of the following bits:
+.IP
+.ad l
+.TS
+lb l.
+TIOCPKT_FLUSHREAD	T{
+The read queue for the terminal is flushed.
+T}
+TIOCPKT_FLUSHWRITE	T{
+The write queue for the terminal is flushed.
+T}
+TIOCPKT_STOP	T{
+Output to the terminal is stopped.
+T}
+TIOCPKT_START	T{
+Output to the terminal is restarted.
+T}
+TIOCPKT_DOSTOP	T{
+The start and stop characters are \fB\[ha]S\fP/\fB\[ha]Q\fP.
+T}
+TIOCPKT_NOSTOP	T{
+The start and stop characters are not \fB\[ha]S\fP/\fB\[ha]Q\fP.
+T}
+.TE
+.ad
+.IP
+While packet mode is in use, the presence
+of control status information to be read
+from the master side may be detected by a
+.BR select (2)
+for exceptional conditions or a
+.BR poll (2)
+for the
+.B POLLPRI
+event.
+.IP
+This mode is used by
+.BR rlogin (1)
+and
+.BR rlogind (8)
+to implement a remote-echoed,
+locally \fB\[ha]S\fP/\fB\[ha]Q\fP flow-controlled remote login.
+.TP
+.B TIOCGPKT
+Argument:
+.BI "const int\~*" argp
+.IP
+(since Linux 3.8)
+Return the current packet mode setting in the integer pointed to by
+.IR argp .
+.TP
+.B TIOCSPTLCK
+Argument:
+.BI "int\~*" argp
+.IP
+Set (if
+.I *argp
+is nonzero) or remove (if
+.I *argp
+is zero) the lock on the pseudoterminal slave device.
+(See also
+.BR unlockpt (3).)
+.TP
+.B TIOCGPTLCK
+Argument:
+.BI "int\~*" argp
+.IP
+(since Linux 3.8)
+Place the current lock state of the pseudoterminal slave device
+in the location pointed to by
+.IR argp .
+.TP
+.B TIOCGPTPEER
+Argument:
+.BI "int " flags
+.IP
+.\" commit 54ebbfb1603415d9953c150535850d30609ef077
+(since Linux 4.13)
+Given a file descriptor in
+.I fd
+that refers to a pseudoterminal master,
+open (with the given
+.BR open (2)-style
+.IR flags )
+and return a new file descriptor that refers to the peer
+pseudoterminal slave device.
+This operation can be performed
+regardless of whether the pathname of the slave device
+is accessible through the calling process's mount namespace.
+.IP
+Security-conscious programs interacting with namespaces may wish to use this
+operation rather than
+.BR open (2)
+with the pathname returned by
+.BR ptsname (3),
+and similar library functions that have insecure APIs.
+(For example, confusion can occur in some cases using
+.BR ptsname (3)
+with a pathname where a devpts filesystem
+has been mounted in a different mount namespace.)
+.P
+The BSD ioctls
+.BR TIOCSTOP ,
+.BR TIOCSTART ,
+.BR TIOCUCNTL ,
+and
+.B TIOCREMOTE
+have not been implemented under Linux.
+.SS Modem control
+.TP
+.B TIOCMGET
+Argument:
+.BI "int\~*" argp
+.IP
+Get the status of modem bits.
+.TP
+.B TIOCMSET
+Argument:
+.BI "const int\~*" argp
+.IP
+Set the status of modem bits.
+.TP
+.B TIOCMBIC
+Argument:
+.BI "const int\~*" argp
+.IP
+Clear the indicated modem bits.
+.TP
+.B TIOCMBIS
+Argument:
+.BI "const int\~*" argp
+.IP
+Set the indicated modem bits.
+.P
+The following bits are used by the above ioctls:
+.P
+.TS
+lb l.
+TIOCM_LE	DSR (data set ready/line enable)
+TIOCM_DTR	DTR (data terminal ready)
+TIOCM_RTS	RTS (request to send)
+TIOCM_ST	Secondary TXD (transmit)
+TIOCM_SR	Secondary RXD (receive)
+TIOCM_CTS	CTS (clear to send)
+TIOCM_CAR	DCD (data carrier detect)
+TIOCM_CD	see TIOCM_CAR
+TIOCM_RNG	RNG (ring)
+TIOCM_RI	see TIOCM_RNG
+TIOCM_DSR	DSR (data set ready)
+.TE
+.TP
+.B TIOCMIWAIT
+Argument:
+.BI "int " arg
+.IP
+Wait for any of the 4 modem bits (DCD, RI, DSR, CTS) to change.
+The bits of interest are specified as a bit mask in
+.IR arg ,
+by ORing together any of the bit values,
+.BR TIOCM_RNG ,
+.BR TIOCM_DSR ,
+.BR TIOCM_CD ,
+and
+.BR TIOCM_CTS .
+The caller should use
+.B TIOCGICOUNT
+to see which bit has changed.
+.TP
+.B TIOCGICOUNT
+Argument:
+.BI "struct serial_icounter_struct\~*" argp
+.IP
+Get counts of input serial line interrupts (DCD, RI, DSR, CTS).
+The counts are written to the
+.I serial_icounter_struct
+structure pointed to by
+.IR argp .
+.IP
+Note: both 1->0 and 0->1 transitions are counted, except for
+RI, where only 0->1 transitions are counted.
+.SS Marking a line as local
+.TP
+.B TIOCGSOFTCAR
+Argument:
+.BI "int\~*" argp
+.IP
+("Get software carrier flag")
+Get the status of the CLOCAL flag in the c_cflag field of the
+.I termios
+structure.
+.TP
+.B TIOCSSOFTCAR
+Argument:
+.BI "const int\~*" argp
+.IP
+("Set software carrier flag")
+Set the CLOCAL flag in the
+.I termios
+structure when
+.RI * argp
+is nonzero, and clear it otherwise.
+.P
+If the
+.B CLOCAL
+flag for a line is off, the hardware carrier detect (DCD)
+signal is significant, and an
+.BR open (2)
+of the corresponding terminal will block until DCD is asserted,
+unless the
+.B O_NONBLOCK
+flag is given.
+If
+.B CLOCAL
+is set, the line behaves as if DCD is always asserted.
+The software carrier flag is usually turned on for local devices,
+and is off for lines with modems.
+.SS Linux-specific
+For the
+.B TIOCLINUX
+ioctl, see
+.BR ioctl_console (2).
+.SS Kernel debugging
+.B "#include <linux/tty.h>"
+.TP
+.B TIOCTTYGSTRUCT
+Argument:
+.BI "struct tty_struct\~*" argp
+.IP
+Get the
+.I tty_struct
+corresponding to
+.IR fd .
+This operation was removed in Linux 2.5.67.
+.\"     commit b3506a09d15dc5aee6d4bb88d759b157016e1864
+.\"     Author: Andries E. Brouwer <andries.brouwer@cwi.nl>
+.\"     Date:   Tue Apr 1 04:42:46 2003 -0800
+.\"
+.\"     [PATCH] kill TIOCTTYGSTRUCT
+.\"
+.\"     Only used for (dubious) debugging purposes, and exposes
+.\"     internal kernel state.
+.\"
+.\" .SS Serial info
+.\" .BR "#include <linux/serial.h>"
+.\" .P
+.\" .TP
+.\" .BI "TIOCGSERIAL	struct serial_struct *" argp
+.\" Get serial info.
+.\" .TP
+.\" .BI "TIOCSSERIAL	const struct serial_struct *" argp
+.\" Set serial info.
+.SH RETURN VALUE
+The
+.BR ioctl (2)
+system call returns 0 on success.
+On error, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+Invalid operation parameter.
+.TP
+.B ENOIOCTLCMD
+Unknown operation.
+.TP
+.B ENOTTY
+Inappropriate
+.IR fd .
+.TP
+.B EPERM
+Insufficient permission.
+.SH EXAMPLES
+Check the condition of DTR on the serial port.
+.P
+.\" SRC BEGIN (tiocmget.c)
+.EX
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+\&
+int
+main(void)
+{
+    int fd, serial;
+\&
+    fd = open("/dev/ttyS0", O_RDONLY);
+    ioctl(fd, TIOCMGET, &serial);
+    if (serial & TIOCM_DTR)
+        puts("TIOCM_DTR is set");
+    else
+        puts("TIOCM_DTR is not set");
+    close(fd);
+}
+.EE
+.\" SRC END
+.P
+Get or set arbitrary baudrate on the serial port.
+.P
+.\" SRC BEGIN (tcgets.c)
+.EX
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+\&
+#include <asm/termbits.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+#if !defined BOTHER
+    fprintf(stderr, "BOTHER is unsupported\en");
+    /* Program may fallback to TCGETS/TCSETS with Bnnn constants */
+    exit(EXIT_FAILURE);
+#else
+    /* Declare tio structure, its type depends on supported ioctl */
+# if defined TCGETS2
+    struct termios2 tio;
+# else
+    struct termios tio;
+# endif
+    int fd, rc;
+\&
+    if (argc != 2 && argc != 3 && argc != 4) {
+        fprintf(stderr, "Usage: %s device [output [input] ]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fd = open(argv[1], O_RDWR | O_NONBLOCK | O_NOCTTY);
+    if (fd < 0) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Get the current serial port settings via supported ioctl */
+# if defined TCGETS2
+    rc = ioctl(fd, TCGETS2, &tio);
+# else
+    rc = ioctl(fd, TCGETS, &tio);
+# endif
+    if (rc) {
+        perror("TCGETS");
+        close(fd);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Change baud rate when more arguments were provided */
+    if (argc == 3 || argc == 4) {
+        /* Clear the current output baud rate and fill a new value */
+        tio.c_cflag &= \[ti]CBAUD;
+        tio.c_cflag |= BOTHER;
+        tio.c_ospeed = atoi(argv[2]);
+\&
+        /* Clear the current input baud rate and fill a new value */
+        tio.c_cflag &= \[ti](CBAUD << IBSHIFT);
+        tio.c_cflag |= BOTHER << IBSHIFT;
+        /* When 4th argument is not provided reuse output baud rate */
+        tio.c_ispeed = (argc == 4) ? atoi(argv[3]) : atoi(argv[2]);
+\&
+        /* Set new serial port settings via supported ioctl */
+# if defined TCSETS2
+        rc = ioctl(fd, TCSETS2, &tio);
+# else
+        rc = ioctl(fd, TCSETS, &tio);
+# endif
+        if (rc) {
+            perror("TCSETS");
+            close(fd);
+            exit(EXIT_FAILURE);
+        }
+\&
+        /* And get new values which were really configured */
+# if defined TCGETS2
+        rc = ioctl(fd, TCGETS2, &tio);
+# else
+        rc = ioctl(fd, TCGETS, &tio);
+# endif
+        if (rc) {
+            perror("TCGETS");
+            close(fd);
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    close(fd);
+\&
+    printf("output baud rate: %u\en", tio.c_ospeed);
+    printf("input baud rate: %u\en", tio.c_ispeed);
+\&
+    exit(EXIT_SUCCESS);
+#endif
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ldattach (8),
+.BR ioctl (2),
+.BR ioctl_console (2),
+.BR termios (3),
+.BR pty (7)
+.\"
+.\" FIONBIO			const int *
+.\" FIONCLEX			void
+.\" FIOCLEX			void
+.\" FIOASYNC			const int *
+.\" from serial.c:
+.\" TIOCSERCONFIG		void
+.\" TIOCSERGWILD		int *
+.\" TIOCSERSWILD		const int *
+.\" TIOCSERGSTRUCT		struct async_struct *
+.\" TIOCSERGETMULTI		struct serial_multiport_struct *
+.\" TIOCSERSETMULTI		const struct serial_multiport_struct *
+.\" TIOCGSERIAL, TIOCSSERIAL (see above)
diff --git a/man/man2/ioctl_userfaultfd.2 b/man/man2/ioctl_userfaultfd.2
new file mode 100644
index 000000000..cbd0c7978
--- /dev/null
+++ b/man/man2/ioctl_userfaultfd.2
@@ -0,0 +1,1072 @@
+.\" Copyright (c) 2016, IBM Corporation.
+.\" Written by Mike Rapoport <rppt@linux.vnet.ibm.com>
+.\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH ioctl_userfaultfd 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioctl_userfaultfd \- create a file descriptor for handling page faults in user
+space
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/userfaultfd.h>" "  /* Definition of " UFFD* " constants */"
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " fd ", int " op ", ...);"
+.fi
+.SH DESCRIPTION
+Various
+.BR ioctl (2)
+operations can be performed on a userfaultfd object (created by a call to
+.BR userfaultfd (2))
+using calls of the form:
+.P
+.in +4n
+.EX
+ioctl(fd, op, argp);
+.EE
+.in
+.P
+In the above,
+.I fd
+is a file descriptor referring to a userfaultfd object,
+.I op
+is one of the operations listed below, and
+.I argp
+is a pointer to a data structure that is specific to
+.IR op .
+.P
+The various
+.BR ioctl (2)
+operations are described below.
+The
+.BR UFFDIO_API ,
+.BR UFFDIO_REGISTER ,
+and
+.B UFFDIO_UNREGISTER
+operations are used to
+.I configure
+userfaultfd behavior.
+These operations allow the caller to choose what features will be enabled and
+what kinds of events will be delivered to the application.
+The remaining operations are
+.I range
+operations.
+These operations enable the calling application to resolve page-fault
+events.
+.\"
+.SS UFFDIO_API
+(Since Linux 4.3.)
+Enable operation of the userfaultfd and perform API handshake.
+.P
+The
+.I argp
+argument is a pointer to a
+.I uffdio_api
+structure, defined as:
+.P
+.in +4n
+.EX
+struct uffdio_api {
+    __u64 api;        /* Requested API version (input) */
+    __u64 features;   /* Requested features (input/output) */
+    __u64 ioctls;     /* Available ioctl() operations (output) */
+};
+.EE
+.in
+.P
+The
+.I api
+field denotes the API version requested by the application.
+The kernel verifies that it can support the requested API version,
+and sets the
+.I features
+and
+.I ioctls
+fields to bit masks representing all the available features and the generic
+.BR ioctl (2)
+operations available.
+.P
+Since Linux 4.11,
+applications should use the
+.I features
+field to perform a two-step handshake.
+First,
+.B UFFDIO_API
+is called with the
+.I features
+field set to zero.
+The kernel responds by setting all supported feature bits.
+.P
+Applications which do not require any specific features
+can begin using the userfaultfd immediately.
+Applications which do need specific features
+should call
+.B UFFDIO_API
+again with a subset of the reported feature bits set
+to enable those features.
+.P
+Before Linux 4.11, the
+.I features
+field must be initialized to zero before the call to
+.BR UFFDIO_API ,
+and zero (i.e., no feature bits) is placed in the
+.I features
+field by the kernel upon return from
+.BR ioctl (2).
+.P
+If the application sets unsupported feature bits,
+the kernel will zero out the returned
+.I uffdio_api
+structure and return
+.BR EINVAL .
+.P
+The following feature bits may be set:
+.TP
+.BR UFFD_FEATURE_EVENT_FORK " (since Linux 4.11)"
+When this feature is enabled,
+the userfaultfd objects associated with a parent process are duplicated
+into the child process during
+.BR fork (2)
+and a
+.B UFFD_EVENT_FORK
+event is delivered to the userfaultfd monitor
+.TP
+.BR UFFD_FEATURE_EVENT_REMAP " (since Linux 4.11)"
+If this feature is enabled,
+when the faulting process invokes
+.BR mremap (2),
+the userfaultfd monitor will receive an event of type
+.BR UFFD_EVENT_REMAP .
+.TP
+.BR UFFD_FEATURE_EVENT_REMOVE " (since Linux 4.11)"
+If this feature is enabled,
+when the faulting process calls
+.BR madvise (2)
+with the
+.B MADV_DONTNEED
+or
+.B MADV_REMOVE
+advice value to free a virtual memory area
+the userfaultfd monitor will receive an event of type
+.BR UFFD_EVENT_REMOVE .
+.TP
+.BR UFFD_FEATURE_EVENT_UNMAP " (since Linux 4.11)"
+If this feature is enabled,
+when the faulting process unmaps virtual memory either explicitly with
+.BR munmap (2),
+or implicitly during either
+.BR mmap (2)
+or
+.BR mremap (2),
+the userfaultfd monitor will receive an event of type
+.BR UFFD_EVENT_UNMAP .
+.TP
+.BR UFFD_FEATURE_MISSING_HUGETLBFS " (since Linux 4.11)"
+If this feature bit is set,
+the kernel supports registering userfaultfd ranges on hugetlbfs
+virtual memory areas
+.TP
+.BR UFFD_FEATURE_MISSING_SHMEM " (since Linux 4.11)"
+If this feature bit is set,
+the kernel supports registering userfaultfd ranges on shared memory areas.
+This includes all kernel shared memory APIs:
+System V shared memory,
+.BR tmpfs (5),
+shared mappings of
+.IR /dev/zero ,
+.BR mmap (2)
+with the
+.B MAP_SHARED
+flag set,
+.BR memfd_create (2),
+and so on.
+.TP
+.BR UFFD_FEATURE_SIGBUS " (since Linux 4.14)"
+.\" commit 2d6d6f5a09a96cc1fec7ed992b825e05f64cb50e
+If this feature bit is set, no page-fault events
+.RB ( UFFD_EVENT_PAGEFAULT )
+will be delivered.
+Instead, a
+.B SIGBUS
+signal will be sent to the faulting process.
+Applications using this
+feature will not require the use of a userfaultfd monitor for processing
+memory accesses to the regions registered with userfaultfd.
+.TP
+.BR UFFD_FEATURE_THREAD_ID " (since Linux 4.14)"
+If this feature bit is set,
+.I uffd_msg.pagefault.feat.ptid
+will be set to the faulted thread ID for each page-fault message.
+.TP
+.BR UFFD_FEATURE_PAGEFAULT_FLAG_WP " (since Linux 5.10)"
+If this feature bit is set,
+userfaultfd supports write-protect faults
+for anonymous memory.
+(Note that shmem / hugetlbfs support
+is indicated by a separate feature.)
+.TP
+.BR UFFD_FEATURE_MINOR_HUGETLBFS " (since Linux 5.13)"
+If this feature bit is set,
+the kernel supports registering userfaultfd ranges
+in minor mode on hugetlbfs-backed memory areas.
+.TP
+.BR UFFD_FEATURE_MINOR_SHMEM " (since Linux 5.14)"
+If this feature bit is set,
+the kernel supports registering userfaultfd ranges
+in minor mode on shmem-backed memory areas.
+.TP
+.BR UFFD_FEATURE_EXACT_ADDRESS " (since Linux 5.18)"
+If this feature bit is set,
+.I uffd_msg.pagefault.address
+will be set to the exact page-fault address that was reported by the hardware,
+and will not mask the offset within the page.
+Note that old Linux versions might indicate the exact address as well,
+even though the feature bit is not set.
+.TP
+.BR UFFD_FEATURE_WP_HUGETLBFS_SHMEM " (since Linux 5.19)"
+If this feature bit is set,
+userfaultfd supports write-protect faults
+for hugetlbfs and shmem / tmpfs memory.
+.TP
+.BR UFFD_FEATURE_WP_UNPOPULATED " (since Linux 6.4)"
+If this feature bit is set,
+the kernel will handle anonymous memory the same way as file memory,
+by allowing the user to write-protect unpopulated page table entries.
+.TP
+.BR UFFD_FEATURE_POISON " (since Linux 6.6)"
+If this feature bit is set,
+the kernel supports resolving faults with the
+.B UFFDIO_POISON
+ioctl.
+.TP
+.BR UFFD_FEATURE_WP_ASYNC " (since Linux 6.7)"
+If this feature bit is set,
+the write protection faults would be asynchronously resolved
+by the kernel.
+.P
+The returned
+.I ioctls
+field can contain the following bits:
+.\" FIXME This user-space API seems not fully polished. Why are there
+.\" not constants defined for each of the bit-mask values listed below?
+.TP
+.B 1 << _UFFDIO_API
+The
+.B UFFDIO_API
+operation is supported.
+.TP
+.B 1 << _UFFDIO_REGISTER
+The
+.B UFFDIO_REGISTER
+operation is supported.
+.TP
+.B 1 << _UFFDIO_UNREGISTER
+The
+.B UFFDIO_UNREGISTER
+operation is supported.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+If an error occurs,
+the kernel may zero the provided
+.I uffdio_api
+structure.
+The caller should treat its contents as unspecified,
+and reinitialize it before re-attempting another
+.B UFFDIO_API
+call.
+Possible errors include:
+.TP
+.B EFAULT
+.I argp
+refers to an address that is outside the calling process's
+accessible address space.
+.TP
+.B EINVAL
+The API version requested in the
+.I api
+field is not supported by this kernel, or the
+.I features
+field passed to the kernel includes feature bits that are not supported
+by the current kernel version.
+.TP
+.B EINVAL
+A previous
+.B UFFDIO_API
+call already enabled one or more features for this userfaultfd.
+Calling
+.B UFFDIO_API
+twice,
+the first time with no features set,
+is explicitly allowed
+as per the two-step feature detection handshake.
+.TP
+.B EPERM
+The
+.B UFFD_FEATURE_EVENT_FORK
+feature was enabled,
+but the calling process doesn't have the
+.B CAP_SYS_PTRACE
+capability.
+.SS UFFDIO_REGISTER
+(Since Linux 4.3.)
+Register a memory address range with the userfaultfd object.
+The pages in the range must be \[lq]compatible\[rq].
+Please refer to the list of register modes below
+for the compatible memory backends for each mode.
+.P
+The
+.I argp
+argument is a pointer to a
+.I uffdio_register
+structure, defined as:
+.P
+.in +4n
+.EX
+struct uffdio_range {
+    __u64 start;    /* Start of range */
+    __u64 len;      /* Length of range (bytes) */
+};
+\&
+struct uffdio_register {
+    struct uffdio_range range;
+    __u64 mode;     /* Desired mode of operation (input) */
+    __u64 ioctls;   /* Available ioctl() operations (output) */
+};
+.EE
+.in
+.P
+The
+.I range
+field defines a memory range starting at
+.I start
+and continuing for
+.I len
+bytes that should be handled by the userfaultfd.
+.P
+The
+.I mode
+field defines the mode of operation desired for this memory region.
+The following values may be bitwise ORed to set the userfaultfd mode for
+the specified range:
+.TP
+.B UFFDIO_REGISTER_MODE_MISSING
+Track page faults on missing pages.
+Since Linux 4.3,
+only private anonymous ranges are compatible.
+Since Linux 4.11,
+hugetlbfs and shared memory ranges are also compatible.
+.TP
+.B UFFDIO_REGISTER_MODE_WP
+Track page faults on write-protected pages.
+Since Linux 5.7,
+only private anonymous ranges are compatible.
+.TP
+.B UFFDIO_REGISTER_MODE_MINOR
+Track minor page faults.
+Since Linux 5.13,
+only hugetlbfs ranges are compatible.
+Since Linux 5.14,
+compatibility with shmem ranges was added.
+.P
+If the operation is successful, the kernel modifies the
+.I ioctls
+bit-mask field to indicate which
+.BR ioctl (2)
+operations are available for the specified range.
+This returned bit mask can contain the following bits:
+.TP
+.B 1 << _UFFDIO_COPY
+The
+.B UFFDIO_COPY
+operation is supported.
+.TP
+.B 1 << _UFFDIO_WAKE
+The
+.B UFFDIO_WAKE
+operation is supported.
+.TP
+.B 1 << _UFFDIO_WRITEPROTECT
+The
+.B UFFDIO_WRITEPROTECT
+operation is supported.
+.TP
+.B 1 << _UFFDIO_ZEROPAGE
+The
+.B UFFDIO_ZEROPAGE
+operation is supported.
+.TP
+.B 1 << _UFFDIO_CONTINUE
+The
+.B UFFDIO_CONTINUE
+operation is supported.
+.TP
+.B 1 << _UFFDIO_POISON
+The
+.B UFFDIO_POISON
+operation is supported.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.\" FIXME Is the following error list correct?
+.\"
+.TP
+.B EBUSY
+A mapping in the specified range is registered with another
+userfaultfd object.
+.TP
+.B EFAULT
+.I argp
+refers to an address that is outside the calling process's
+accessible address space.
+.TP
+.B EINVAL
+An invalid or unsupported bit was specified in the
+.I mode
+field; or the
+.I mode
+field was zero.
+.TP
+.B EINVAL
+There is no mapping in the specified address range.
+.TP
+.B EINVAL
+.I range.start
+or
+.I range.len
+is not a multiple of the system page size; or,
+.I range.len
+is zero; or these fields are otherwise invalid.
+.TP
+.B EINVAL
+There as an incompatible mapping in the specified address range.
+.\" Mike Rapoport:
+.\" ENOMEM if the process is exiting and the
+.\" mm_struct has gone by the time userfault grabs it.
+.SS UFFDIO_UNREGISTER
+(Since Linux 4.3.)
+Unregister a memory address range from userfaultfd.
+The pages in the range must be \[lq]compatible\[rq]
+(see the description of
+.BR UFFDIO_REGISTER .)
+.P
+The address range to unregister is specified in the
+.I uffdio_range
+structure pointed to by
+.IR argp .
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.TP
+.B EINVAL
+Either the
+.I start
+or the
+.I len
+field of the
+.I ufdio_range
+structure was not a multiple of the system page size; or the
+.I len
+field was zero; or these fields were otherwise invalid.
+.TP
+.B EINVAL
+There as an incompatible mapping in the specified address range.
+.TP
+.B EINVAL
+There was no mapping in the specified address range.
+.\"
+.SS UFFDIO_COPY
+(Since Linux 4.3.)
+Atomically copy a continuous memory chunk into the userfault registered
+range and optionally wake up the blocked thread.
+The source and destination addresses and the number of bytes to copy are
+specified by the
+.IR src ,
+.IR dst ,
+and
+.I len
+fields of the
+.I uffdio_copy
+structure pointed to by
+.IR argp :
+.P
+.in +4n
+.EX
+struct uffdio_copy {
+    __u64 dst;    /* Destination of copy */
+    __u64 src;    /* Source of copy */
+    __u64 len;    /* Number of bytes to copy */
+    __u64 mode;   /* Flags controlling behavior of copy */
+    __s64 copy;   /* Number of bytes copied, or negated error */
+};
+.EE
+.in
+.P
+The following value may be bitwise ORed in
+.I mode
+to change the behavior of the
+.B UFFDIO_COPY
+operation:
+.TP
+.B UFFDIO_COPY_MODE_DONTWAKE
+Do not wake up the thread that waits for page-fault resolution
+.TP
+.B UFFDIO_COPY_MODE_WP
+Copy the page with read-only permission.
+This allows the user to trap the next write to the page,
+which will block and generate another write-protect userfault message.
+This is used only when both
+.B UFFDIO_REGISTER_MODE_MISSING
+and
+.B UFFDIO_REGISTER_MODE_WP
+modes are enabled for the registered range.
+.P
+The
+.I copy
+field is used by the kernel to return the number of bytes
+that was actually copied, or an error (a negated
+.IR errno -style
+value).
+.\" FIXME Above: Why is the 'copy' field used to return error values?
+.\" This should be explained in the manual page.
+If the value returned in
+.I copy
+doesn't match the value that was specified in
+.IR len ,
+the operation fails with the error
+.BR EAGAIN .
+The
+.I copy
+field is output-only;
+it is not read by the
+.B UFFDIO_COPY
+operation.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+In this case, the entire area was copied.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.TP
+.B EAGAIN
+The number of bytes copied (i.e., the value returned in the
+.I copy
+field)
+does not equal the value that was specified in the
+.I len
+field.
+.TP
+.B EINVAL
+Either
+.I dst
+or
+.I len
+was not a multiple of the system page size, or the range specified by
+.I src
+and
+.I len
+or
+.I dst
+and
+.I len
+was invalid.
+.TP
+.B EINVAL
+An invalid bit was specified in the
+.I mode
+field.
+.TP
+.BR ENOENT " (since Linux 4.11)"
+The faulting process has changed
+its virtual memory layout simultaneously with an outstanding
+.B UFFDIO_COPY
+operation.
+.TP
+.BR ENOSPC " (from Linux 4.11 until Linux 4.13)"
+The faulting process has exited at the time of a
+.B UFFDIO_COPY
+operation.
+.TP
+.BR ESRCH " (since Linux 4.13)"
+The faulting process has exited at the time of a
+.B UFFDIO_COPY
+operation.
+.\"
+.SS UFFDIO_ZEROPAGE
+(Since Linux 4.3.)
+Zero out a memory range registered with userfaultfd.
+.P
+The requested range is specified by the
+.I range
+field of the
+.I uffdio_zeropage
+structure pointed to by
+.IR argp :
+.P
+.in +4n
+.EX
+struct uffdio_zeropage {
+    struct uffdio_range range;
+    __u64 mode;     /* Flags controlling behavior of copy */
+    __s64 zeropage; /* Number of bytes zeroed, or negated error */
+};
+.EE
+.in
+.P
+The following value may be bitwise ORed in
+.I mode
+to change the behavior of the
+.B UFFDIO_ZEROPAGE
+operation:
+.TP
+.B UFFDIO_ZEROPAGE_MODE_DONTWAKE
+Do not wake up the thread that waits for page-fault resolution.
+.P
+The
+.I zeropage
+field is used by the kernel to return the number of bytes
+that was actually zeroed,
+or an error in the same manner as
+.BR UFFDIO_COPY .
+.\" FIXME Why is the 'zeropage' field used to return error values?
+.\" This should be explained in the manual page.
+If the value returned in the
+.I zeropage
+field doesn't match the value that was specified in
+.IR range.len ,
+the operation fails with the error
+.BR EAGAIN .
+The
+.I zeropage
+field is output-only;
+it is not read by the
+.B UFFDIO_ZEROPAGE
+operation.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+In this case, the entire area was zeroed.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.TP
+.B EAGAIN
+The number of bytes zeroed (i.e., the value returned in the
+.I zeropage
+field)
+does not equal the value that was specified in the
+.I range.len
+field.
+.TP
+.B EINVAL
+Either
+.I range.start
+or
+.I range.len
+was not a multiple of the system page size; or
+.I range.len
+was zero; or the range specified was invalid.
+.TP
+.B EINVAL
+An invalid bit was specified in the
+.I mode
+field.
+.TP
+.BR ESRCH " (since Linux 4.13)"
+The faulting process has exited at the time of a
+.B UFFDIO_ZEROPAGE
+operation.
+.\"
+.SS UFFDIO_WAKE
+(Since Linux 4.3.)
+Wake up the thread waiting for page-fault resolution on
+a specified memory address range.
+.P
+The
+.B UFFDIO_WAKE
+operation is used in conjunction with
+.B UFFDIO_COPY
+and
+.B UFFDIO_ZEROPAGE
+operations that have the
+.B UFFDIO_COPY_MODE_DONTWAKE
+or
+.B UFFDIO_ZEROPAGE_MODE_DONTWAKE
+bit set in the
+.I mode
+field.
+The userfault monitor can perform several
+.B UFFDIO_COPY
+and
+.B UFFDIO_ZEROPAGE
+operations in a batch and then explicitly wake up the faulting thread using
+.BR UFFDIO_WAKE .
+.P
+The
+.I argp
+argument is a pointer to a
+.I uffdio_range
+structure (shown above) that specifies the address range.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.TP
+.B EINVAL
+The
+.I start
+or the
+.I len
+field of the
+.I ufdio_range
+structure was not a multiple of the system page size; or
+.I len
+was zero; or the specified range was otherwise invalid.
+.SS UFFDIO_WRITEPROTECT
+(Since Linux 5.7.)
+Write-protect or write-unprotect a userfaultfd-registered memory range
+registered with mode
+.BR UFFDIO_REGISTER_MODE_WP .
+.P
+The
+.I argp
+argument is a pointer to a
+.I uffdio_range
+structure as shown below:
+.P
+.in +4n
+.EX
+struct uffdio_writeprotect {
+    struct uffdio_range range; /* Range to change write permission*/
+    __u64 mode;                /* Mode to change write permission */
+};
+.EE
+.in
+.P
+There are two mode bits that are supported in this structure:
+.TP
+.B UFFDIO_WRITEPROTECT_MODE_WP
+When this mode bit is set,
+the ioctl will be a write-protect operation upon the memory range specified by
+.IR range .
+Otherwise it will be a write-unprotect operation upon the specified range,
+which can be used to resolve a userfaultfd write-protect page fault.
+.TP
+.B UFFDIO_WRITEPROTECT_MODE_DONTWAKE
+When this mode bit is set,
+do not wake up any thread that waits for
+page-fault resolution after the operation.
+This can be specified only if
+.B UFFDIO_WRITEPROTECT_MODE_WP
+is not specified.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.TP
+.B EINVAL
+The
+.I start
+or the
+.I len
+field of the
+.I ufdio_range
+structure was not a multiple of the system page size; or
+.I len
+was zero; or the specified range was otherwise invalid.
+.TP
+.B EAGAIN
+The process was interrupted; retry this call.
+.TP
+.B ENOENT
+The range specified in
+.I range
+is not valid.
+For example, the virtual address does not exist,
+or not registered with userfaultfd write-protect mode.
+.TP
+.B EFAULT
+Encountered a generic fault during processing.
+.\"
+.SS UFFDIO_CONTINUE
+(Since Linux 5.13.)
+Resolve a minor page fault
+by installing page table entries
+for existing pages in the page cache.
+.P
+The
+.I argp
+argument is a pointer to a
+.I uffdio_continue
+structure as shown below:
+.P
+.in +4n
+.EX
+struct uffdio_continue {
+    struct uffdio_range range;
+                   /* Range to install PTEs for and continue */
+    __u64 mode;    /* Flags controlling the behavior of continue */
+    __s64 mapped;  /* Number of bytes mapped, or negated error */
+};
+.EE
+.in
+.P
+The following value may be bitwise ORed in
+.I mode
+to change the behavior of the
+.B UFFDIO_CONTINUE
+operation:
+.TP
+.B UFFDIO_CONTINUE_MODE_DONTWAKE
+Do not wake up the thread that waits for page-fault resolution.
+.P
+The
+.I mapped
+field is used by the kernel
+to return the number of bytes that were actually mapped,
+or an error in the same manner as
+.BR UFFDIO_COPY .
+If the value returned in the
+.I mapped
+field doesn't match the value that was specified in
+.IR range.len ,
+the operation fails with the error
+.BR EAGAIN .
+The
+.I mapped
+field is output-only;
+it is not read by the
+.B UFFDIO_CONTINUE
+operation.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+In this case,
+the entire area was mapped.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.TP
+.B EAGAIN
+The number of bytes mapped
+(i.e., the value returned in the
+.I mapped
+field)
+does not equal the value that was specified in the
+.I range.len
+field.
+.TP
+.B EEXIST
+One or more pages were already mapped in the given range.
+.TP
+.B EFAULT
+No existing page could be found in the page cache for the given range.
+.TP
+.B EINVAL
+Either
+.I range.start
+or
+.I range.len
+was not a multiple of the system page size; or
+.I range.len
+was zero; or the range specified was invalid.
+.TP
+.B EINVAL
+An invalid bit was specified in the
+.I mode
+field.
+.TP
+.B ENOENT
+The faulting process has changed its virtual memory layout simultaneously with
+an outstanding
+.B UFFDIO_CONTINUE
+operation.
+.TP
+.B ENOMEM
+Allocating memory needed to setup the page table mappings failed.
+.TP
+.B ESRCH
+The faulting process has exited at the time of a
+.B UFFDIO_CONTINUE
+operation.
+.\"
+.SS UFFDIO_POISON
+(Since Linux 6.6.)
+Mark an address range as "poisoned".
+Future accesses to these addresses will raise a
+.B SIGBUS
+signal.
+Unlike
+.B MADV_HWPOISON
+this works by installing page table entries,
+rather than "really" poisoning the underlying physical pages.
+This means it only affects this particular address space.
+.P
+The
+.I argp
+argument is a pointer to a
+.I uffdio_poison
+structure as shown below:
+.P
+.in +4n
+.EX
+struct uffdio_poison {
+	struct uffdio_range range;
+	                /* Range to install poison PTE markers in */
+	__u64 mode;     /* Flags controlling the behavior of poison */
+	__s64 updated;  /* Number of bytes poisoned, or negated error */
+};
+.EE
+.in
+.P
+The following value may be bitwise ORed in
+.I mode
+to change the behavior of the
+.B UFFDIO_POISON
+operation:
+.TP
+.B UFFDIO_POISON_MODE_DONTWAKE
+Do not wake up the thread that waits for page-fault resolution.
+.P
+The
+.I updated
+field is used by the kernel
+to return the number of bytes that were actually poisoned,
+or an error in the same manner as
+.BR UFFDIO_COPY .
+If the value returned in the
+.I updated
+field doesn't match the value that was specified in
+.IR range.len ,
+the operation fails with the error
+.BR EAGAIN .
+The
+.I updated
+field is output-only;
+it is not read by the
+.B UFFDIO_POISON
+operation.
+.P
+This
+.BR ioctl (2)
+operation returns 0 on success.
+In this case,
+the entire area was poisoned.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+Possible errors include:
+.TP
+.B EAGAIN
+The number of bytes mapped
+(i.e., the value returned in the
+.I updated
+field)
+does not equal the value that was specified in the
+.I range.len
+field.
+.TP
+.B EINVAL
+Either
+.I range.start
+or
+.I range.len
+was not a multiple of the system page size; or
+.I range.len
+was zero; or the range specified was invalid.
+.TP
+.B EINVAL
+An invalid bit was specified in the
+.I mode
+field.
+.TP
+.B EEXIST
+One or more pages were already mapped in the given range.
+.TP
+.B ENOENT
+The faulting process has changed its virtual memory layout simultaneously with
+an outstanding
+.B UFFDIO_POISON
+operation.
+.TP
+.B ENOMEM
+Allocating memory for page table entries failed.
+.TP
+.B ESRCH
+The faulting process has exited at the time of a
+.B UFFDIO_POISON
+operation.
+.\"
+.SH RETURN VALUE
+See descriptions of the individual operations, above.
+.SH ERRORS
+See descriptions of the individual operations, above.
+In addition, the following general errors can occur for all of the
+operations described above:
+.TP
+.B EFAULT
+.I argp
+does not point to a valid memory address.
+.TP
+.B EINVAL
+(For all operations except
+.BR UFFDIO_API .)
+The userfaultfd object has not yet been enabled (via the
+.B UFFDIO_API
+operation).
+.SH STANDARDS
+Linux.
+.SH BUGS
+In order to detect available userfault features and
+enable some subset of those features
+the userfaultfd file descriptor must be closed after the first
+.B UFFDIO_API
+operation that queries features availability and reopened before
+the second
+.B UFFDIO_API
+operation that actually enables the desired features.
+.SH EXAMPLES
+See
+.BR userfaultfd (2).
+.SH SEE ALSO
+.BR ioctl (2),
+.BR mmap (2),
+.BR userfaultfd (2)
+.P
+.I Documentation/admin\-guide/mm/userfaultfd.rst
+in the Linux kernel source tree
diff --git a/man/man2/ioperm.2 b/man/man2/ioperm.2
new file mode 100644
index 000000000..a2cde4721
--- /dev/null
+++ b/man/man2/ioperm.2
@@ -0,0 +1,105 @@
+.\" Copyright (c) 1993 Michael Haardt
+.\" (michael@moria.de)
+.\" Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 15:12:05 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Aug  1 16:27    1995 by Jochen Karrer
+.\"                              <cip307@cip.physik.uni-wuerzburg.de>
+.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Mon Feb 15 17:28:41 CET 1999 by Andries E. Brouwer <aeb@cwi.nl>
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.TH ioperm 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioperm \- set port input/output permissions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/io.h>
+.P
+.BI "int ioperm(unsigned long " from ", unsigned long " num ", int " turn_on );
+.fi
+.SH DESCRIPTION
+.BR ioperm ()
+sets the port access permission bits for the calling thread for
+.I num
+bits starting from port address
+.IR from .
+If
+.I turn_on
+is nonzero, then permission for the specified bits is enabled;
+otherwise it is disabled.
+If
+.I turn_on
+is nonzero, the calling thread must be privileged
+.RB ( CAP_SYS_RAWIO ).
+.P
+Before Linux 2.6.8,
+only the first 0x3ff I/O ports could be specified in this manner.
+For more ports, the
+.BR iopl (2)
+system call had to be used (with a
+.I level
+argument of 3).
+Since Linux 2.6.8, 65,536 I/O ports can be specified.
+.P
+Permissions are inherited by the child created by
+.BR fork (2)
+(but see NOTES).
+Permissions are preserved across
+.BR execve (2);
+this is useful for giving port access permissions to unprivileged
+programs.
+.P
+This call is mostly for the i386 architecture.
+On many other architectures it does not exist or will always
+return an error.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+Invalid values for
+.I from
+or
+.IR num .
+.TP
+.B EIO
+(on PowerPC) This call is not supported.
+.TP
+.B ENOMEM
+.\" Could not allocate I/O bitmap.
+Out of memory.
+.TP
+.B EPERM
+The calling thread has insufficient privilege.
+.SH VERSIONS
+glibc has an
+.BR ioperm ()
+prototype both in
+.I <sys/io.h>
+and in
+.IR <sys/perm.h> .
+Avoid the latter, it is available on i386 only.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Before Linux 2.4,
+permissions were not inherited by a child created by
+.BR fork (2).
+.SH NOTES
+The
+.I /proc/ioports
+file shows the I/O ports that are currently allocated on the system.
+.SH SEE ALSO
+.BR iopl (2),
+.BR outb (2),
+.BR capabilities (7)
diff --git a/man/man2/iopl.2 b/man/man2/iopl.2
new file mode 100644
index 000000000..8279336e3
--- /dev/null
+++ b/man/man2/iopl.2
@@ -0,0 +1,92 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\" Portions extracted from linux/kernel/ioport.c (no copyright notice).
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Tue Aug  1 16:47    1995 by Jochen Karrer
+.\"                              <cip307@cip.physik.uni-wuerzburg.de>
+.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Fri Nov 27 14:50:36 CET 1998 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.TH iopl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iopl \- change I/O privilege level
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/io.h>
+.P
+.BI "[[deprecated]] int iopl(int " level );
+.fi
+.SH DESCRIPTION
+.BR iopl ()
+changes the I/O privilege level of the calling thread,
+as specified by the two least significant bits in
+.IR level .
+.P
+The I/O privilege level for a normal thread is 0.
+Permissions are inherited from parents to children.
+.P
+This call is deprecated, is significantly slower than
+.BR ioperm (2),
+and is only provided for older X servers which require
+access to all 65536 I/O ports.
+It is mostly for the i386 architecture.
+On many other architectures it does not exist or will always
+return an error.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I level
+is greater than 3.
+.TP
+.B ENOSYS
+This call is unimplemented.
+.TP
+.B EPERM
+The calling thread has insufficient privilege to call
+.BR iopl ();
+the
+.B CAP_SYS_RAWIO
+capability is required to raise the I/O privilege level
+above its current value.
+.SH VERSIONS
+.\" Libc5 treats it as a system call and has a prototype in
+.\" .IR <unistd.h> .
+.\" glibc1 does not have a prototype.
+glibc2 has a prototype both in
+.I <sys/io.h>
+and in
+.IR <sys/perm.h> .
+Avoid the latter, it is available on i386 only.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Prior to Linux 5.5
+.BR iopl ()
+allowed the thread to disable interrupts while running
+at a higher I/O privilege level.
+This will probably crash the system, and is not recommended.
+.P
+Prior to Linux 3.7,
+on some architectures (such as i386), permissions
+.I were
+inherited by the child produced by
+.BR fork (2)
+and were preserved across
+.BR execve (2).
+This behavior was inadvertently changed in Linux 3.7,
+and won't be reinstated.
+.SH SEE ALSO
+.BR ioperm (2),
+.BR outb (2),
+.BR capabilities (7)
diff --git a/man/man2/ioprio_get.2 b/man/man2/ioprio_get.2
new file mode 100644
index 000000000..d6d5b3b68
--- /dev/null
+++ b/man/man2/ioprio_get.2
@@ -0,0 +1 @@
+.so man2/ioprio_set.2
diff --git a/man/man2/ioprio_set.2 b/man/man2/ioprio_set.2
new file mode 100644
index 000000000..b4b9fe080
--- /dev/null
+++ b/man/man2/ioprio_set.2
@@ -0,0 +1,362 @@
+.\" Copyright (c) International Business Machines orp., 2006
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" HISTORY:
+.\" 2006-04-27, created by Eduardo M. Fleury <efleury@br.ibm.com>
+.\" with various additions by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\"
+.TH ioprio_set 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ioprio_get, ioprio_set \- get/set I/O scheduling class and priority
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/ioprio.h>    " "/* Definition of " IOPRIO_* " constants */"
+.BR "#include <sys/syscall.h>     " "/* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_ioprio_get, int " which ", int " who );
+.BI "int syscall(SYS_ioprio_set, int " which ", int " who ", int " ioprio );
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR ioprio_get ()
+and
+.BR ioprio_set ()
+system calls get and set the I/O scheduling class and
+priority of one or more threads.
+.P
+The
+.I which
+and
+.I who
+arguments identify the thread(s) on which the system
+calls operate.
+The
+.I which
+argument determines how
+.I who
+is interpreted, and has one of the following values:
+.TP
+.B IOPRIO_WHO_PROCESS
+.I who
+is a process ID or thread ID identifying a single process or thread.
+If
+.I who
+is 0, then operate on the calling thread.
+.TP
+.B IOPRIO_WHO_PGRP
+.I who
+is a process group ID identifying all the members of a process group.
+If
+.I who
+is 0, then operate on the process group of which the caller is a member.
+.TP
+.B IOPRIO_WHO_USER
+.I who
+is a user ID identifying all of the processes that
+have a matching real UID.
+.\" FIXME . Need to document the behavior when 'who" is specified as 0
+.\" See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=652443
+.P
+If
+.I which
+is specified as
+.B IOPRIO_WHO_PGRP
+or
+.B IOPRIO_WHO_USER
+when calling
+.BR ioprio_get (),
+and more than one process matches
+.IR who ,
+then the returned priority will be the highest one found among
+all of the matching processes.
+One priority is said to be
+higher than another one if it belongs to a higher priority
+class
+.RB ( IOPRIO_CLASS_RT
+is the highest priority class;
+.B IOPRIO_CLASS_IDLE
+is the lowest)
+or if it belongs to the same priority class as the other process but
+has a higher priority level (a lower priority number means a
+higher priority level).
+.P
+The
+.I ioprio
+argument given to
+.BR ioprio_set ()
+is a bit mask that specifies both the scheduling class and the
+priority to be assigned to the target process(es).
+The following macros are used for assembling and dissecting
+.I ioprio
+values:
+.TP
+.BI IOPRIO_PRIO_VALUE( class ", " data )
+Given a scheduling
+.I class
+and priority
+.RI ( data ),
+this macro combines the two values to produce an
+.I ioprio
+value, which is returned as the result of the macro.
+.TP
+.BI IOPRIO_PRIO_CLASS( mask )
+Given
+.I mask
+(an
+.I ioprio
+value), this macro returns its I/O class component, that is,
+one of the values
+.BR IOPRIO_CLASS_RT ,
+.BR IOPRIO_CLASS_BE ,
+or
+.BR IOPRIO_CLASS_IDLE .
+.TP
+.BI IOPRIO_PRIO_DATA( mask )
+Given
+.I mask
+(an
+.I ioprio
+value), this macro returns its priority
+.RI ( data )
+component.
+.P
+See the NOTES section for more
+information on scheduling classes and priorities,
+as well as the meaning of specifying
+.I ioprio
+as 0.
+.P
+I/O priorities are supported for reads and for synchronous
+.RB ( O_DIRECT ,
+.BR O_SYNC )
+writes.
+I/O priorities are not supported for asynchronous
+writes because they are issued outside the context of the program
+dirtying the memory, and thus program-specific priorities do not apply.
+.SH RETURN VALUE
+On success,
+.BR ioprio_get ()
+returns the
+.I ioprio
+value of the process with highest I/O priority of any of the processes
+that match the criteria specified in
+.I which
+and
+.IR who .
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+On success,
+.BR ioprio_set ()
+returns 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+Invalid value for
+.I which
+or
+.IR ioprio .
+Refer to the NOTES section for available scheduler
+classes and priority levels for
+.IR ioprio .
+.TP
+.B EPERM
+The calling process does not have the privilege needed to assign this
+.I ioprio
+to the specified process(es).
+See the NOTES section for more information on required
+privileges for
+.BR ioprio_set ().
+.TP
+.B ESRCH
+No process(es) could be found that matched the specification in
+.I which
+and
+.IR who .
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.13.
+.SH NOTES
+Two or more processes or threads can share an I/O context.
+This will be the case when
+.BR clone (2)
+was called with the
+.B CLONE_IO
+flag.
+However, by default, the distinct threads of a process will
+.B not
+share the same I/O context.
+This means that if you want to change the I/O
+priority of all threads in a process, you may need to call
+.BR ioprio_set ()
+on each of the threads.
+The thread ID that you would need for this operation
+is the one that is returned by
+.BR gettid (2)
+or
+.BR clone (2).
+.P
+These system calls have an effect only when used
+in conjunction with an I/O scheduler that supports I/O priorities.
+As at kernel 2.6.17 the only such scheduler is the Completely Fair Queuing
+(CFQ) I/O scheduler.
+.P
+If no I/O scheduler has been set for a thread,
+then by default the I/O priority will follow the CPU nice value
+.RB ( setpriority (2)).
+Before Linux 2.6.24,
+once an I/O priority had been set using
+.BR ioprio_set (),
+there was no way to reset the I/O scheduling behavior to the default.
+Since Linux 2.6.24,
+.\" commit 8ec680e4c3ec818efd1652f15199ed1c216ab550
+specifying
+.I ioprio
+as 0 can be used to reset to the default I/O scheduling behavior.
+.SS Selecting an I/O scheduler
+I/O schedulers are selected on a per-device basis via the special
+file
+.IR /sys/block/ device /queue/scheduler .
+.P
+One can view the current I/O scheduler via the
+.I /sys
+filesystem.
+For example, the following command
+displays a list of all schedulers currently loaded in the kernel:
+.P
+.in +4n
+.EX
+.RB "$" " cat /sys/block/sda/queue/scheduler"
+noop anticipatory deadline [cfq]
+.EE
+.in
+.P
+The scheduler surrounded by brackets is the one actually
+in use for the device
+.RI ( sda
+in the example).
+Setting another scheduler is done by writing the name of the
+new scheduler to this file.
+For example, the following command will set the
+scheduler for the
+.I sda
+device to
+.IR cfq :
+.P
+.in +4n
+.EX
+.RB "$" " su"
+Password:
+.RB "#" " echo cfq > /sys/block/sda/queue/scheduler"
+.EE
+.in
+.\"
+.SS The Completely Fair Queuing (CFQ) I/O scheduler
+Since version 3 (also known as CFQ Time Sliced), CFQ implements
+I/O nice levels similar to those
+of CPU scheduling.
+These nice levels are grouped into three scheduling classes,
+each one containing one or more priority levels:
+.TP
+.BR IOPRIO_CLASS_RT " (1)"
+This is the real-time I/O class.
+This scheduling class is given
+higher priority than any other class:
+processes from this class are
+given first access to the disk every time.
+Thus, this I/O class needs to be used with some
+care: one I/O real-time process can starve the entire system.
+Within the real-time class,
+there are 8 levels of class data (priority) that determine exactly
+how much time this process needs the disk for on each service.
+The highest real-time priority level is 0; the lowest is 7.
+In the future, this might change to be more directly mappable to
+performance, by passing in a desired data rate instead.
+.TP
+.BR IOPRIO_CLASS_BE " (2)"
+This is the best-effort scheduling class,
+which is the default for any process
+that hasn't set a specific I/O priority.
+The class data (priority) determines how much
+I/O bandwidth the process will get.
+Best-effort priority levels are analogous to CPU nice values
+(see
+.BR getpriority (2)).
+The priority level determines a priority relative
+to other processes in the best-effort scheduling class.
+Priority levels range from 0 (highest) to 7 (lowest).
+.TP
+.BR IOPRIO_CLASS_IDLE " (3)"
+This is the idle scheduling class.
+Processes running at this level get I/O
+time only when no one else needs the disk.
+The idle class has no class data.
+Attention is required when assigning this priority class to a process,
+since it may become starved if higher priority processes are
+constantly accessing the disk.
+.P
+Refer to the kernel source file
+.I Documentation/block/ioprio.txt
+for more information on the CFQ I/O Scheduler and an example program.
+.SS Required permissions to set I/O priorities
+Permission to change a process's priority is granted or denied based
+on two criteria:
+.TP
+.B "Process ownership"
+An unprivileged process may set the I/O priority only for a process
+whose real UID
+matches the real or effective UID of the calling process.
+A process which has the
+.B CAP_SYS_NICE
+capability can change the priority of any process.
+.TP
+.B "What is the desired priority"
+Attempts to set very high priorities
+.RB ( IOPRIO_CLASS_RT )
+require the
+.B CAP_SYS_ADMIN
+capability.
+Up to Linux 2.6.24 also required
+.B CAP_SYS_ADMIN
+to set a very low priority
+.RB ( IOPRIO_CLASS_IDLE ),
+but since Linux 2.6.25, this is no longer required.
+.P
+A call to
+.BR ioprio_set ()
+must follow both rules, or the call will fail with the error
+.BR EPERM .
+.SH BUGS
+.\" 6 May 07: Bug report raised:
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=4464
+.\" Ulrich Drepper replied that he wasn't going to add these
+.\" to glibc.
+glibc does not yet provide a suitable header file defining
+the function prototypes and macros described on this page.
+Suitable definitions can be found in
+.IR linux/ioprio.h .
+.SH SEE ALSO
+.BR ionice (1),
+.BR getpriority (2),
+.BR open (2),
+.BR capabilities (7),
+.BR cgroups (7)
+.P
+.I Documentation/block/ioprio.txt
+in the Linux kernel source tree
diff --git a/man/man2/ipc.2 b/man/man2/ipc.2
new file mode 100644
index 000000000..91eb1ac50
--- /dev/null
+++ b/man/man2/ipc.2
@@ -0,0 +1,63 @@
+.\" Copyright (c) 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.TH ipc 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ipc \- System V IPC system calls
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/ipc.h>" "        /* Definition of needed constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_ipc, unsigned int " call ", int " first ,
+.BI "            unsigned long " second ", unsigned long " third \
+", void *" ptr ,
+.BI "            long " fifth );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR ipc (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR ipc ()
+is a common kernel entry point for the System\ V IPC calls
+for messages, semaphores, and shared memory.
+.I call
+determines which IPC function to invoke;
+the other arguments are passed through to the appropriate call.
+.P
+User-space programs should call the appropriate functions by their usual names.
+Only standard library implementors and kernel hackers need to know about
+.BR ipc ().
+.SH VERSIONS
+On some architectures\[em]for example x86-64 and ARM\[em]there is no
+.BR ipc ()
+system call; instead,
+.BR msgctl (2),
+.BR semctl (2),
+.BR shmctl (2),
+and so on really are implemented as separate system calls.
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR msgctl (2),
+.BR msgget (2),
+.BR msgrcv (2),
+.BR msgsnd (2),
+.BR semctl (2),
+.BR semget (2),
+.BR semop (2),
+.BR semtimedop (2),
+.BR shmat (2),
+.BR shmctl (2),
+.BR shmdt (2),
+.BR shmget (2),
+.BR sysvipc (7)
diff --git a/man/man2/isastream.2 b/man/man2/isastream.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/isastream.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/kcmp.2 b/man/man2/kcmp.2
new file mode 100644
index 000000000..0ea604eac
--- /dev/null
+++ b/man/man2/kcmp.2
@@ -0,0 +1,420 @@
+.\" Copyright (C) 2012, Cyrill Gorcunov <gorcunov@openvz.org>
+.\" and Copyright (C) 2012, 2016, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Kernel commit d97b46a64674a267bc41c9e16132ee2a98c3347d
+.\"
+.TH kcmp 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+kcmp \- compare two processes to determine if they share a kernel resource
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/kcmp.h>" "       /* Definition of " KCMP_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_kcmp, pid_t " pid1 ", pid_t " pid2 ", int " type ,
+.BI "            unsigned long " idx1 ", unsigned long "  idx2 );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR kcmp (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR kcmp ()
+system call can be used to check whether the two processes identified by
+.I pid1
+and
+.I pid2
+share a kernel resource such as virtual memory, file descriptors,
+and so on.
+.P
+Permission to employ
+.BR kcmp ()
+is governed by ptrace access mode
+.B PTRACE_MODE_READ_REALCREDS
+checks against both
+.I pid1
+and
+.IR pid2 ;
+see
+.BR ptrace (2).
+.P
+The
+.I type
+argument specifies which resource is to be compared in the two processes.
+It has one of the following values:
+.TP
+.B KCMP_FILE
+Check whether a file descriptor
+.I idx1
+in the process
+.I pid1
+refers to the same open file description (see
+.BR open (2))
+as file descriptor
+.I idx2
+in the process
+.IR pid2 .
+The existence of two file descriptors that refer to the same
+open file description can occur as a result of
+.BR dup (2)
+(and similar)
+.BR fork (2),
+or passing file descriptors via a domain socket (see
+.BR unix (7)).
+.TP
+.B KCMP_FILES
+Check whether the processes share the same set of open file descriptors.
+The arguments
+.I idx1
+and
+.I idx2
+are ignored.
+See the discussion of the
+.B CLONE_FILES
+flag in
+.BR clone (2).
+.TP
+.B KCMP_FS
+Check whether the processes share the same filesystem information
+(i.e., file mode creation mask, working directory, and filesystem root).
+The arguments
+.I idx1
+and
+.I idx2
+are ignored.
+See the discussion of the
+.B CLONE_FS
+flag in
+.BR clone (2).
+.TP
+.B KCMP_IO
+Check whether the processes share I/O context.
+The arguments
+.I idx1
+and
+.I idx2
+are ignored.
+See the discussion of the
+.B CLONE_IO
+flag in
+.BR clone (2).
+.TP
+.B KCMP_SIGHAND
+Check whether the processes share the same table of signal dispositions.
+The arguments
+.I idx1
+and
+.I idx2
+are ignored.
+See the discussion of the
+.B CLONE_SIGHAND
+flag in
+.BR clone (2).
+.TP
+.B KCMP_SYSVSEM
+Check whether the processes share the same
+list of System\ V semaphore undo operations.
+The arguments
+.I idx1
+and
+.I idx2
+are ignored.
+See the discussion of the
+.B CLONE_SYSVSEM
+flag in
+.BR clone (2).
+.TP
+.B KCMP_VM
+Check whether the processes share the same address space.
+The arguments
+.I idx1
+and
+.I idx2
+are ignored.
+See the discussion of the
+.B CLONE_VM
+flag in
+.BR clone (2).
+.TP
+.BR KCMP_EPOLL_TFD " (since Linux 4.13)"
+.\" commit 0791e3644e5ef21646fe565b9061788d05ec71d4
+Check whether the file descriptor
+.I idx1
+of the process
+.I pid1
+is present in the
+.BR epoll (7)
+instance described by
+.I idx2
+of the process
+.IR pid2 .
+The argument
+.I idx2
+is a pointer to a structure where the target file is described.
+This structure has the form:
+.P
+.in +4n
+.EX
+struct kcmp_epoll_slot {
+    __u32 efd;
+    __u32 tfd;
+    __u64 toff;
+};
+.EE
+.in
+.P
+Within this structure,
+.I efd
+is an epoll file descriptor returned from
+.BR epoll_create (2),
+.I tfd
+is a target file descriptor number, and
+.I toff
+is a target file offset counted from zero.
+Several different targets may be registered with
+the same file descriptor number and setting a specific
+offset helps to investigate each of them.
+.P
+Note the
+.BR kcmp ()
+is not protected against false positives which may occur if
+the processes are currently running.
+One should stop the processes by sending
+.B SIGSTOP
+(see
+.BR signal (7))
+prior to inspection with this system call to obtain meaningful results.
+.SH RETURN VALUE
+The return value of a successful call to
+.BR kcmp ()
+is simply the result of arithmetic comparison
+of kernel pointers (when the kernel compares resources, it uses their
+memory addresses).
+.P
+The easiest way to explain is to consider an example.
+Suppose that
+.I v1
+and
+.I v2
+are the addresses of appropriate resources, then the return value
+is one of the following:
+.RS
+.TP
+.B 0
+.I v1
+is equal to
+.IR v2 ;
+in other words, the two processes share the resource.
+.TP
+.B 1
+.I v1
+is less than
+.IR v2 .
+.TP
+.B 2
+.I v1
+is greater than
+.IR v2 .
+.TP
+.B 3
+.I v1
+is not equal to
+.IR v2 ,
+but ordering information is unavailable.
+.RE
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+.BR kcmp ()
+was designed to return values suitable for sorting.
+This is particularly handy if one needs to compare
+a large number of file descriptors.
+.SH ERRORS
+.TP
+.B EBADF
+.I type
+is
+.B KCMP_FILE
+and
+.I fd1
+or
+.I fd2
+is not an open file descriptor.
+.TP
+.B EFAULT
+The epoll slot addressed by
+.I idx2
+is outside of the user's address space.
+.TP
+.B EINVAL
+.I type
+is invalid.
+.TP
+.B ENOENT
+The target file is not present in
+.BR epoll (7)
+instance.
+.TP
+.B EPERM
+Insufficient permission to inspect process resources.
+The
+.B CAP_SYS_PTRACE
+capability is required to inspect processes that you do not own.
+Other ptrace limitations may also apply, such as
+.BR CONFIG_SECURITY_YAMA ,
+which, when
+.I /proc/sys/kernel/yama/ptrace_scope
+is 2, limits
+.BR kcmp ()
+to child processes;
+see
+.BR ptrace (2).
+.TP
+.B ESRCH
+Process
+.I pid1
+or
+.I pid2
+does not exist.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.5.
+.P
+Before Linux 5.12,
+this system call is available only if the kernel is configured with
+.BR CONFIG_CHECKPOINT_RESTORE ,
+since the original purpose of the system call was for the
+checkpoint/restore in user space (CRIU) feature.
+(The alternative to this system call would have been to expose suitable
+process information via the
+.BR proc (5)
+filesystem; this was deemed to be unsuitable for security reasons.)
+Since Linux 5.12,
+this system call is also available if the kernel is configured with
+.BR CONFIG_KCMP .
+.SH NOTES
+See
+.BR clone (2)
+for some background information on the shared resources
+referred to on this page.
+.SH EXAMPLES
+The program below uses
+.BR kcmp ()
+to test whether pairs of file descriptors refer to
+the same open file description.
+The program tests different cases for the file descriptor pairs,
+as described in the program output.
+An example run of the program is as follows:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+Parent PID is 1144
+Parent opened file on FD 3
+\&
+PID of child of fork() is 1145
+	Compare duplicate FDs from different processes:
+		kcmp(1145, 1144, KCMP_FILE, 3, 3) ==> same
+Child opened file on FD 4
+	Compare FDs from distinct open()s in same process:
+		kcmp(1145, 1145, KCMP_FILE, 3, 4) ==> different
+Child duplicated FD 3 to create FD 5
+	Compare duplicated FDs in same process:
+		kcmp(1145, 1145, KCMP_FILE, 3, 5) ==> same
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (kcmp.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <fcntl.h>
+#include <linux/kcmp.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <unistd.h>
+\&
+static int
+kcmp(pid_t pid1, pid_t pid2, int type,
+     unsigned long idx1, unsigned long idx2)
+{
+    return syscall(SYS_kcmp, pid1, pid2, type, idx1, idx2);
+}
+\&
+static void
+test_kcmp(char *msg, pid_t pid1, pid_t pid2, int fd_a, int fd_b)
+{
+    printf("\et%s\en", msg);
+    printf("\et\etkcmp(%jd, %jd, KCMP_FILE, %d, %d) ==> %s\en",
+           (intmax_t) pid1, (intmax_t) pid2, fd_a, fd_b,
+           (kcmp(pid1, pid2, KCMP_FILE, fd_a, fd_b) == 0) ?
+                        "same" : "different");
+}
+\&
+int
+main(void)
+{
+    int                fd1, fd2, fd3;
+    static const char  pathname[] = "/tmp/kcmp.test";
+\&
+    fd1 = open(pathname, O_CREAT | O_RDWR, 0600);
+    if (fd1 == \-1)
+        err(EXIT_FAILURE, "open");
+\&
+    printf("Parent PID is %jd\en", (intmax_t) getpid());
+    printf("Parent opened file on FD %d\en\en", fd1);
+\&
+    switch (fork()) {
+    case \-1:
+        err(EXIT_FAILURE, "fork");
+\&
+    case 0:
+        printf("PID of child of fork() is %jd\en", (intmax_t) getpid());
+\&
+        test_kcmp("Compare duplicate FDs from different processes:",
+                  getpid(), getppid(), fd1, fd1);
+\&
+        fd2 = open(pathname, O_CREAT | O_RDWR, 0600);
+        if (fd2 == \-1)
+            err(EXIT_FAILURE, "open");
+        printf("Child opened file on FD %d\en", fd2);
+\&
+        test_kcmp("Compare FDs from distinct open()s in same process:",
+                  getpid(), getpid(), fd1, fd2);
+\&
+        fd3 = dup(fd1);
+        if (fd3 == \-1)
+            err(EXIT_FAILURE, "dup");
+        printf("Child duplicated FD %d to create FD %d\en", fd1, fd3);
+\&
+        test_kcmp("Compare duplicated FDs in same process:",
+                  getpid(), getpid(), fd1, fd3);
+        break;
+\&
+    default:
+        wait(NULL);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clone (2),
+.BR unshare (2)
diff --git a/man/man2/kexec_file_load.2 b/man/man2/kexec_file_load.2
new file mode 100644
index 000000000..6c20331d3
--- /dev/null
+++ b/man/man2/kexec_file_load.2
@@ -0,0 +1 @@
+.so man2/kexec_load.2
diff --git a/man/man2/kexec_load.2 b/man/man2/kexec_load.2
new file mode 100644
index 000000000..58a894f30
--- /dev/null
+++ b/man/man2/kexec_load.2
@@ -0,0 +1,331 @@
+.\" Copyright (C) 2010 Intel Corporation, Author: Andi Kleen
+.\" and Copyright 2014, Vivek Goyal <vgoyal@redhat.com>
+.\" and Copyright (c) 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH kexec_load 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+kexec_load, kexec_file_load \- load a new kernel for later execution
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/kexec.h>" "      /* Definition of " KEXEC_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(SYS_kexec_load, unsigned long " entry ,
+.BI "             unsigned long " nr_segments \
+", struct kexec_segment *" segments ,
+.BI "             unsigned long " flags );
+.BI "long syscall(SYS_kexec_file_load, int " kernel_fd ", int " initrd_fd ,
+.BI "             unsigned long " cmdline_len ", const char *" cmdline ,
+.BI "             unsigned long " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR kexec_load ()
+system call loads a new kernel that can be executed later by
+.BR reboot (2).
+.P
+The
+.I flags
+argument is a bit mask that controls the operation of the call.
+The following values can be specified in
+.IR flags :
+.TP
+.BR KEXEC_ON_CRASH " (since Linux 2.6.13)"
+Execute the new kernel automatically on a system crash.
+This "crash kernel" is loaded into an area of reserved memory that
+is determined at boot time using the
+.I crashkernel
+kernel command-line parameter.
+The location of this reserved memory is exported to user space via the
+.I /proc/iomem
+file, in an entry labeled "Crash kernel".
+A user-space application can parse this file and prepare a list of
+segments (see below) that specify this reserved memory as destination.
+If this flag is specified, the kernel checks that the
+target segments specified in
+.I segments
+fall within the reserved region.
+.TP
+.BR KEXEC_PRESERVE_CONTEXT " (since Linux 2.6.27)"
+Preserve the system hardware and
+software states before executing the new kernel.
+This could be used for system suspend.
+This flag is available only if the kernel was configured with
+.BR CONFIG_KEXEC_JUMP ,
+and is effective only if
+.I nr_segments
+is greater than 0.
+.P
+The high-order bits (corresponding to the mask 0xffff0000) of
+.I flags
+contain the architecture of the to-be-executed kernel.
+Specify (OR) the constant
+.B KEXEC_ARCH_DEFAULT
+to use the current architecture,
+or one of the following architecture constants
+.BR KEXEC_ARCH_386 ,
+.BR KEXEC_ARCH_68K ,
+.BR KEXEC_ARCH_X86_64 ,
+.BR KEXEC_ARCH_PPC ,
+.BR KEXEC_ARCH_PPC64 ,
+.BR KEXEC_ARCH_IA_64 ,
+.BR KEXEC_ARCH_ARM ,
+.BR KEXEC_ARCH_S390 ,
+.BR KEXEC_ARCH_SH ,
+.BR KEXEC_ARCH_MIPS ,
+and
+.BR KEXEC_ARCH_MIPS_LE .
+The architecture must be executable on the CPU of the system.
+.P
+The
+.I entry
+argument is the physical entry address in the kernel image.
+The
+.I nr_segments
+argument is the number of segments pointed to by the
+.I segments
+pointer;
+the kernel imposes an (arbitrary) limit of 16 on the number of segments.
+The
+.I segments
+argument is an array of
+.I kexec_segment
+structures which define the kernel layout:
+.P
+.in +4n
+.EX
+struct kexec_segment {
+    void   *buf;        /* Buffer in user space */
+    size_t  bufsz;      /* Buffer length in user space */
+    void   *mem;        /* Physical address of kernel */
+    size_t  memsz;      /* Physical address length */
+};
+.EE
+.in
+.P
+The kernel image defined by
+.I segments
+is copied from the calling process into
+the kernel either in regular
+memory or in reserved memory (if
+.B KEXEC_ON_CRASH
+is set).
+The kernel first performs various sanity checks on the
+information passed in
+.IR segments .
+If these checks pass, the kernel copies the segment data to kernel memory.
+Each segment specified in
+.I segments
+is copied as follows:
+.IP \[bu] 3
+.I buf
+and
+.I bufsz
+identify a memory region in the caller's virtual address space
+that is the source of the copy.
+The value in
+.I bufsz
+may not exceed the value in the
+.I memsz
+field.
+.IP \[bu]
+.I mem
+and
+.I memsz
+specify a physical address range that is the target of the copy.
+The values specified in both fields must be multiples of
+the system page size.
+.IP \[bu]
+.I bufsz
+bytes are copied from the source buffer to the target kernel buffer.
+If
+.I bufsz
+is less than
+.IR memsz ,
+then the excess bytes in the kernel buffer are zeroed out.
+.P
+In case of a normal kexec (i.e., the
+.B KEXEC_ON_CRASH
+flag is not set), the segment data is loaded in any available memory
+and is moved to the final destination at kexec reboot time (e.g., when the
+.BR kexec (8)
+command is executed with the
+.I \-e
+option).
+.P
+In case of kexec on panic (i.e., the
+.B KEXEC_ON_CRASH
+flag is set), the segment data is
+loaded to reserved memory at the time of the call, and, after a crash,
+the kexec mechanism simply passes control to that kernel.
+.P
+The
+.BR kexec_load ()
+system call is available only if the kernel was configured with
+.BR CONFIG_KEXEC .
+.SS kexec_file_load()
+The
+.BR kexec_file_load ()
+system call is similar to
+.BR kexec_load (),
+but it takes a different set of arguments.
+It reads the kernel to be loaded from the file referred to by
+the file descriptor
+.IR kernel_fd ,
+and the initrd (initial RAM disk)
+to be loaded from file referred to by the file descriptor
+.IR initrd_fd .
+The
+.I cmdline
+argument is a pointer to a buffer containing the command line
+for the new kernel.
+The
+.I cmdline_len
+argument specifies size of the buffer.
+The last byte in the buffer must be a null byte (\[aq]\e0\[aq]).
+.P
+The
+.I flags
+argument is a bit mask which modifies the behavior of the call.
+The following values can be specified in
+.IR flags :
+.TP
+.B KEXEC_FILE_UNLOAD
+Unload the currently loaded kernel.
+.TP
+.B KEXEC_FILE_ON_CRASH
+Load the new kernel in the memory region reserved for the crash kernel
+(as for
+.BR KEXEC_ON_CRASH ).
+This kernel is booted if the currently running kernel crashes.
+.TP
+.B KEXEC_FILE_NO_INITRAMFS
+Loading initrd/initramfs is optional.
+Specify this flag if no initramfs is being loaded.
+If this flag is set, the value passed in
+.I initrd_fd
+is ignored.
+.P
+The
+.BR kexec_file_load ()
+.\" See also http://lwn.net/Articles/603116/
+system call was added to provide support for systems
+where "kexec" loading should be restricted to
+only kernels that are signed.
+This system call is available only if the kernel was configured with
+.BR CONFIG_KEXEC_FILE .
+.SH RETURN VALUE
+On success, these system calls returns 0.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EADDRNOTAVAIL
+.\" See kernel/kexec.::sanity_check_segment_list in the 3.19 kernel source
+The
+.B KEXEC_ON_CRASH
+flags was specified, but the region specified by the
+.I mem
+and
+.I memsz
+fields of one of the
+.I segments
+entries lies outside the range of memory reserved for the crash kernel.
+.TP
+.B EADDRNOTAVAIL
+The value in a
+.I mem
+or
+.I memsz
+field in one of the
+.I segments
+entries is not a multiple of the system page size.
+.TP
+.B EBADF
+.I kernel_fd
+or
+.I initrd_fd
+is not a valid file descriptor.
+.TP
+.B EBUSY
+Another crash kernel is already being loaded
+or a crash kernel is already in use.
+.TP
+.B EINVAL
+.I flags
+is invalid.
+.TP
+.B EINVAL
+The value of a
+.I bufsz
+field in one of the
+.I segments
+entries exceeds the value in the corresponding
+.I memsz
+field.
+.TP
+.B EINVAL
+.I nr_segments
+exceeds
+.B KEXEC_SEGMENT_MAX
+(16).
+.TP
+.B EINVAL
+Two or more of the kernel target buffers overlap.
+.TP
+.B EINVAL
+The value in
+.I cmdline[cmdline_len\-1]
+is not \[aq]\e0\[aq].
+.TP
+.B EINVAL
+The file referred to by
+.I kernel_fd
+or
+.I initrd_fd
+is empty (length zero).
+.TP
+.B ENOEXEC
+.I kernel_fd
+does not refer to an open file, or the kernel can't load this file.
+Currently, the file must be a bzImage and contain an x86 kernel that
+is loadable above 4\ GiB in memory (see the kernel source file
+.IR Documentation/x86/boot.txt ).
+.TP
+.B ENOMEM
+Could not allocate memory.
+.TP
+.B EPERM
+The caller does not have the
+.B CAP_SYS_BOOT
+capability.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR kexec_load ()
+Linux 2.6.13.
+.TP
+.BR kexec_file_load ()
+Linux 3.17.
+.SH SEE ALSO
+.BR reboot (2),
+.BR syscall (2),
+.BR kexec (8)
+.P
+The kernel source files
+.I Documentation/kdump/kdump.txt
+and
+.I Documentation/admin\-guide/kernel\-parameters.txt
diff --git a/man/man2/keyctl.2 b/man/man2/keyctl.2
new file mode 100644
index 000000000..a2a4ab047
--- /dev/null
+++ b/man/man2/keyctl.2
@@ -0,0 +1,2297 @@
+.\" Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2016 Eugene Syromyatnikov <evgsyr@gmail.com>
+.\" A very few fragments remain from an earlier version of this page
+.\" written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH keyctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+keyctl \- manipulate the kernel's key management facility
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.P
+Alternatively, Linux Key Management Utilities
+.RI ( libkeyutils ", " \-lkeyutils );
+see VERSIONS.
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/keyctl.h>" "     /* Definition of " KEY* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(SYS_keyctl, int " operation ", unsigned long " arg2 ,
+.BI "             unsigned long " arg3 ", unsigned long " arg4 ,
+.BI "             unsigned long " arg5 );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR keyctl (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR keyctl ()
+allows user-space programs to perform key manipulation.
+.P
+The operation performed by
+.BR keyctl ()
+is determined by the value of the
+.I operation
+argument.
+Each of these operations is wrapped by the
+.I libkeyutils
+library (provided by the
+.I keyutils
+package) into individual functions (noted below)
+to permit the compiler to check types.
+.P
+The permitted values for
+.I operation
+are:
+.TP
+.BR KEYCTL_GET_KEYRING_ID " (since Linux 2.6.10)"
+Map a special key ID to a real key ID for this process.
+.IP
+This operation looks up the special key whose ID is provided in
+.I arg2
+(cast to
+.IR key_serial_t ).
+If the special key is found,
+the ID of the corresponding real key is returned as the function result.
+The following values may be specified in
+.IR arg2 :
+.RS
+.TP
+.B KEY_SPEC_THREAD_KEYRING
+This specifies the calling thread's thread-specific keyring.
+See
+.BR thread\-keyring (7).
+.TP
+.B KEY_SPEC_PROCESS_KEYRING
+This specifies the caller's process-specific keyring.
+See
+.BR process\-keyring (7).
+.TP
+.B KEY_SPEC_SESSION_KEYRING
+This specifies the caller's session-specific keyring.
+See
+.BR session\-keyring (7).
+.TP
+.B KEY_SPEC_USER_KEYRING
+This specifies the caller's UID-specific keyring.
+See
+.BR user\-keyring (7).
+.TP
+.B KEY_SPEC_USER_SESSION_KEYRING
+This specifies the caller's UID-session keyring.
+See
+.BR user\-session\-keyring (7).
+.TP
+.BR KEY_SPEC_REQKEY_AUTH_KEY " (since Linux 2.6.16)"
+.\"            commit b5f545c880a2a47947ba2118b2509644ab7a2969
+This specifies the authorization key created by
+.BR request_key (2)
+and passed to the process it spawns to generate a key.
+This key is available only in a
+.BR request\-key (8)-style
+program that was passed an authorization key by the kernel and
+ceases to be available once the requested key has been instantiated; see
+.BR request_key (2).
+.TP
+.BR KEY_SPEC_REQUESTOR_KEYRING " (since Linux 2.6.29)"
+.\"            commit 8bbf4976b59fc9fc2861e79cab7beb3f6d647640
+This specifies the key ID for the
+.BR request_key (2)
+destination keyring.
+This keyring is available only in a
+.BR request\-key (8)-style
+program that was passed an authorization key by the kernel and
+ceases to be available once the requested key has been instantiated; see
+.BR request_key (2).
+.RE
+.IP
+The behavior if the key specified in
+.I arg2
+does not exist depends on the value of
+.I arg3
+(cast to
+.IR int ).
+If
+.I arg3
+contains a nonzero value, then\[em]if it is appropriate to do so
+(e.g., when looking up the user, user-session, or session key)\[em]a new key
+is created and its real key ID returned as the function result.
+.\" The keyctl_get_keyring_ID.3 page says that a new key
+.\" "will be created *if it is appropriate to do so**. What is the
+.\" determiner for appropriate?
+.\" David Howells: Some special keys such as KEY_SPEC_REQKEY_AUTH_KEY
+.\" wouldn't get created but user/user-session/session keyring would
+.\" be created.
+Otherwise, the operation fails with the error
+.BR ENOKEY .
+.IP
+If a valid key ID is specified in
+.IR arg2 ,
+and the key exists, then this operation simply returns the key ID.
+If the key does not exist, the call fails with error
+.BR ENOKEY .
+.IP
+The caller must have
+.I search
+permission on a keyring in order for it to be found.
+.IP
+The arguments
+.I arg4
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_get_keyring_ID (3).
+.TP
+.BR KEYCTL_JOIN_SESSION_KEYRING " (since Linux 2.6.10)"
+Replace the session keyring this process subscribes to with
+a new session keyring.
+.\" This may be useful in conjunction with some sort of
+.\" session management framework that is employed by the application.
+.IP
+If
+.I arg2
+is NULL,
+an anonymous keyring with the description "_ses" is created
+and the process is subscribed to that keyring as its session keyring,
+displacing the previous session keyring.
+.IP
+Otherwise,
+.I arg2
+(cast to
+.IR "char\ *" )
+is treated as the description (name) of a keyring,
+and the behavior is as follows:
+.RS
+.IP \[bu] 3
+If a keyring with a matching description exists,
+the process will attempt to subscribe to that keyring
+as its session keyring if possible;
+if that is not possible, an error is returned.
+In order to subscribe to the keyring,
+the caller must have
+.I search
+permission on the keyring.
+.IP \[bu]
+If a keyring with a matching description does not exist,
+then a new keyring with the specified description is created,
+and the process is subscribed to that keyring as its session keyring.
+.RE
+.IP
+The arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_join_session_keyring (3).
+.TP
+.BR KEYCTL_UPDATE " (since Linux 2.6.10)"
+Update a key's data payload.
+.IP
+The
+.I arg2
+argument (cast to
+.IR key_serial_t )
+specifies the ID of the key to be updated.
+The
+.I arg3
+argument (cast to
+.IR "void\ *" )
+points to the new payload and
+.I arg4
+(cast to
+.IR size_t )
+contains the new payload size in bytes.
+.IP
+The caller must have
+.I write
+permission on the key specified and the key type must support updating.
+.IP
+A negatively instantiated key (see the description of
+.BR KEYCTL_REJECT )
+can be positively instantiated with this operation.
+.IP
+The
+.I arg5
+argument is ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_update (3).
+.TP
+.BR KEYCTL_REVOKE " (since Linux 2.6.10)"
+Revoke the key with the ID provided in
+.I arg2
+(cast to
+.IR key_serial_t ).
+The key is scheduled for garbage collection;
+it will no longer be findable,
+and will be unavailable for further operations.
+Further attempts to use the key will fail with the error
+.BR EKEYREVOKED .
+.IP
+The caller must have
+.I write
+or
+.I setattr
+permission on the key.
+.\" Keys with the KEY_FLAG_KEEP bit set cause an EPERM
+.\" error for KEYCTL_REVOKE. Does this need to be documented?
+.\" David Howells: No significance for user space.
+.IP
+The arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_revoke (3).
+.TP
+.BR KEYCTL_CHOWN " (since Linux 2.6.10)"
+Change the ownership (user and group ID) of a key.
+.IP
+The
+.I arg2
+argument (cast to
+.IR key_serial_t )
+contains the key ID.
+The
+.I arg3
+argument (cast to
+.IR uid_t )
+contains the new user ID (or \-1 in case the user ID shouldn't be changed).
+The
+.I arg4
+argument (cast to
+.IR gid_t )
+contains the new group ID (or \-1 in case the group ID shouldn't be changed).
+.IP
+The key must grant the caller
+.I setattr
+permission.
+.IP
+For the UID to be changed, or for the GID to be changed to a group
+the caller is not a member of, the caller must have the
+.B CAP_SYS_ADMIN
+capability (see
+.BR capabilities (7)).
+.IP
+If the UID is to be changed, the new user must have sufficient
+quota to accept the key.
+The quota deduction will be removed from the old user
+to the new user should the UID be changed.
+.IP
+The
+.I arg5
+argument is ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_chown (3).
+.TP
+.BR KEYCTL_SETPERM " (since Linux 2.6.10)"
+Change the permissions of the key with the ID provided in the
+.I arg2
+argument (cast to
+.IR key_serial_t )
+to the permissions provided in the
+.I arg3
+argument (cast to
+.IR key_perm_t ).
+.IP
+If the caller doesn't have the
+.B CAP_SYS_ADMIN
+capability, it can change permissions only for the keys it owns.
+(More precisely: the caller's filesystem UID must match the UID of the key.)
+.IP
+The key must grant
+.I setattr
+permission to the caller
+.I regardless
+of the caller's capabilities.
+.\" FIXME Above, is it really intended that a privileged process can't
+.\" override the lack of the 'setattr' permission?
+.IP
+The permissions in
+.I arg3
+specify masks of available operations
+for each of the following user categories:
+.RS
+.TP
+.IR possessor " (since Linux 2.6.14)"
+.\" commit 664cceb0093b755739e56572b836a99104ee8a75
+This is the permission granted to a process that possesses the key
+(has it attached searchably to one of the process's keyrings);
+see
+.BR keyrings (7).
+.TP
+.I user
+This is the permission granted to a process
+whose filesystem UID matches the UID of the key.
+.TP
+.I group
+This is the permission granted to a process
+whose filesystem GID or any of its supplementary GIDs
+matches the GID of the key.
+.TP
+.I other
+This is the permission granted to other processes
+that do not match the
+.I user
+and
+.I group
+categories.
+.RE
+.IP
+The
+.IR user ,
+.IR group ,
+and
+.I other
+categories are exclusive: if a process matches the
+.I user
+category, it will not receive permissions granted in the
+.I group
+category; if a process matches the
+.I user
+or
+.I group
+category, then it will not receive permissions granted in the
+.I other
+category.
+.IP
+The
+.I possessor
+category grants permissions that are cumulative with the grants from the
+.IR user ,
+.IR group ,
+or
+.I other
+category.
+.IP
+Each permission mask is eight bits in size,
+with only six bits currently used.
+The available permissions are:
+.RS
+.TP
+.I view
+This permission allows reading attributes of a key.
+.IP
+This permission is required for the
+.B KEYCTL_DESCRIBE
+operation.
+.IP
+The permission bits for each category are
+.BR KEY_POS_VIEW ,
+.BR KEY_USR_VIEW ,
+.BR KEY_GRP_VIEW ,
+and
+.BR KEY_OTH_VIEW .
+.TP
+.I read
+This permission allows reading a key's payload.
+.IP
+This permission is required for the
+.B KEYCTL_READ
+operation.
+.IP
+The permission bits for each category are
+.BR KEY_POS_READ ,
+.BR KEY_USR_READ ,
+.BR KEY_GRP_READ ,
+and
+.BR KEY_OTH_READ .
+.TP
+.I write
+This permission allows update or instantiation of a key's payload.
+For a keyring, it allows keys to be linked and unlinked from the keyring,
+.IP
+This permission is required for the
+.BR KEYCTL_UPDATE ,
+.BR KEYCTL_REVOKE ,
+.BR KEYCTL_CLEAR ,
+.BR KEYCTL_LINK ,
+and
+.B KEYCTL_UNLINK
+operations.
+.IP
+The permission bits for each category are
+.BR KEY_POS_WRITE ,
+.BR KEY_USR_WRITE ,
+.BR KEY_GRP_WRITE ,
+and
+.BR KEY_OTH_WRITE .
+.TP
+.I search
+This permission allows keyrings to be searched and keys to be found.
+Searches can recurse only into nested keyrings that have
+.I search
+permission set.
+.IP
+This permission is required for the
+.BR KEYCTL_GET_KEYRING_ID ,
+.BR KEYCTL_JOIN_SESSION_KEYRING ,
+.BR KEYCTL_SEARCH ,
+and
+.B KEYCTL_INVALIDATE
+operations.
+.IP
+The permission bits for each category are
+.BR KEY_POS_SEARCH ,
+.BR KEY_USR_SEARCH ,
+.BR KEY_GRP_SEARCH ,
+and
+.BR KEY_OTH_SEARCH .
+.TP
+.I link
+This permission allows a key or keyring to be linked to.
+.IP
+This permission is required for the
+.B KEYCTL_LINK
+and
+.B KEYCTL_SESSION_TO_PARENT
+operations.
+.IP
+The permission bits for each category are
+.BR KEY_POS_LINK ,
+.BR KEY_USR_LINK ,
+.BR KEY_GRP_LINK ,
+and
+.BR KEY_OTH_LINK .
+.TP
+.IR setattr " (since Linux 2.6.15)."
+This permission allows a key's UID, GID, and permissions mask to be changed.
+.IP
+This permission is required for the
+.BR KEYCTL_REVOKE ,
+.BR KEYCTL_CHOWN ,
+and
+.B KEYCTL_SETPERM
+operations.
+.IP
+The permission bits for each category are
+.BR KEY_POS_SETATTR ,
+.BR KEY_USR_SETATTR ,
+.BR KEY_GRP_SETATTR ,
+and
+.BR KEY_OTH_SETATTR .
+.RE
+.IP
+As a convenience, the following macros are defined as masks for
+all of the permission bits in each of the user categories:
+.BR KEY_POS_ALL ,
+.BR KEY_USR_ALL ,
+.BR KEY_GRP_ALL ,
+and
+.BR KEY_OTH_ALL .
+.IP
+The
+.I arg4
+and
+.I arg5
+arguments are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_setperm (3).
+.TP
+.BR KEYCTL_DESCRIBE " (since Linux 2.6.10)"
+Obtain a string describing the attributes of a specified key.
+.IP
+The ID of the key to be described is specified in
+.I arg2
+(cast to
+.IR key_serial_t ).
+The descriptive string is returned in the buffer pointed to by
+.I arg3
+(cast to
+.IR char\~* );
+.I arg4
+(cast to
+.IR size_t )
+specifies the size of that buffer in bytes.
+.IP
+The key must grant the caller
+.I view
+permission.
+.IP
+The returned string is null-terminated and
+contains the following information about the key:
+.IP
+.in +4n
+.IR type ; uid ; gid ; perm ; description
+.in
+.IP
+In the above,
+.I type
+and
+.I description
+are strings,
+.I uid
+and
+.I gid
+are decimal strings, and
+.I perm
+is a hexadecimal permissions mask.
+The descriptive string is written with the following format:
+.IP
+.in +4n
+.EX
+%s;%d;%d;%08x;%s
+.EE
+.in
+.IP
+.B Note: the intention is that the descriptive string should
+.B be extensible in future kernel versions.
+In particular, the
+.I description
+field will not contain semicolons;
+.\" FIXME But, the kernel does not enforce the requirement
+.\" that the key description contains no semicolons!
+.\" So, user space has no guarantee here??
+.\" Either something more needs to be said here,
+.\" or a kernel fix is required.
+it should be parsed by working backwards from the end of the string
+to find the last semicolon.
+This allows future semicolon-delimited fields to be inserted
+in the descriptive string in the future.
+.IP
+Writing to the buffer is attempted only when
+.I arg3
+is non-NULL and the specified buffer size
+is large enough to accept the descriptive string
+(including the terminating null byte).
+.\" Function commentary says it copies up to buflen bytes, but see the
+.\" (buffer && buflen >= ret) condition in keyctl_describe_key() in
+.\" security/keyctl.c
+In order to determine whether the buffer size was too small,
+check to see if the return value of the operation is greater than
+.IR arg4 .
+.IP
+The
+.I arg5
+argument is ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_describe (3).
+.TP
+.B KEYCTL_CLEAR
+Clear the contents of (i.e., unlink all keys from) a keyring.
+.IP
+The ID of the key
+(which must be of keyring type)
+.\" or the error ENOTDIR results
+is provided in
+.I arg2
+(cast to
+.IR key_serial_t ).
+.\" According to Documentation/security/keys.txt:
+.\"     This function can also be used to clear special kernel keyrings if they
+.\"     are appropriately marked if the user has CAP_SYS_ADMIN capability.  The
+.\"     DNS resolver cache keyring is an example of this.
+.IP
+The caller must have
+.I write
+permission on the keyring.
+.IP
+The arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_clear (3).
+.TP
+.BR KEYCTL_LINK " (since Linux 2.6.10)"
+Create a link from a keyring to a key.
+.IP
+The key to be linked is specified in
+.I arg2
+(cast to
+.IR key_serial_t );
+the keyring is specified in
+.I arg3
+(cast to
+.IR key_serial_t ).
+.IP
+If a key with the same type and description is already linked in the keyring,
+then that key is displaced from the keyring.
+.IP
+Before creating the link,
+the kernel checks the nesting of the keyrings and returns appropriate errors
+if the link would produce a cycle
+or if the nesting of keyrings would be too deep
+(The limit on the nesting of keyrings is determined by the kernel constant
+.BR KEYRING_SEARCH_MAX_DEPTH ,
+defined with the value 6, and is necessary to prevent overflows
+on the kernel stack when recursively searching keyrings).
+.IP
+The caller must have
+.I link
+permission on the key being added and
+.I write
+permission on the keyring.
+.IP
+The arguments
+.I arg4
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_link (3).
+.TP
+.BR KEYCTL_UNLINK " (since Linux 2.6.10)"
+Unlink a key from a keyring.
+.IP
+The ID of the key to be unlinked is specified in
+.I arg2
+(cast to
+.IR key_serial_t );
+the ID of the keyring from which it is to be unlinked is specified in
+.I arg3
+(cast to
+.IR key_serial_t ).
+.IP
+If the key is not currently linked into the keyring, an error results.
+.IP
+The caller must have
+.I write
+permission on the keyring from which the key is being removed.
+.IP
+If the last link to a key is removed,
+then that key will be scheduled for destruction.
+.IP
+The arguments
+.I arg4
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_unlink (3).
+.TP
+.BR KEYCTL_SEARCH " (since Linux 2.6.10)"
+Search for a key in a keyring tree,
+returning its ID and optionally linking it to a specified keyring.
+.IP
+The tree to be searched is specified by passing
+the ID of the head keyring in
+.I arg2
+(cast to
+.IR key_serial_t ).
+The search is performed breadth-first and recursively.
+.IP
+The
+.I arg3
+and
+.I arg4
+arguments specify the key to be searched for:
+.I arg3
+(cast as
+.IR char\~* )
+contains the key type
+(a null-terminated character string up to 32 bytes in size,
+including the terminating null byte), and
+.I arg4
+(cast as
+.IR char\~* )
+contains the description of the key
+(a null-terminated character string up to 4096 bytes in size,
+including the terminating null byte).
+.IP
+The source keyring must grant
+.I search
+permission to the caller.
+When performing the recursive search, only keyrings that grant the caller
+.I search
+permission will be searched.
+Only keys with for which the caller has
+.I search
+permission can be found.
+.IP
+If the key is found, its ID is returned as the function result.
+.IP
+If the key is found and
+.I arg5
+(cast to
+.IR key_serial_t )
+is nonzero, then, subject to the same constraints and rules as
+.BR KEYCTL_LINK ,
+the key is linked into the keyring whose ID is specified in
+.IR arg5 .
+If the destination keyring specified in
+.I arg5
+already contains a link to a key that has the same type and description,
+then that link will be displaced by a link to
+the key found by this operation.
+.IP
+Instead of valid existing keyring IDs, the source
+.RI ( arg2 )
+and destination
+.RI ( arg5 )
+keyrings can be one of the special keyring IDs listed under
+.BR KEYCTL_GET_KEYRING_ID .
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_search (3).
+.TP
+.BR KEYCTL_READ " (since Linux 2.6.10)"
+Read the payload data of a key.
+.IP
+The ID of the key whose payload is to be read is specified in
+.I arg2
+(cast to
+.IR key_serial_t ).
+This can be the ID of an existing key,
+or any of the special key IDs listed for
+.BR KEYCTL_GET_KEYRING_ID .
+.\" including KEY_SPEC_REQKEY_AUTH_KEY
+.IP
+The payload is placed in the buffer pointed by
+.I arg3
+(cast to
+.IR "char\ *" );
+the size of that buffer must be specified in
+.I arg4
+(cast to
+.IR size_t ).
+.IP
+The returned data will be processed for presentation
+according to the key type.
+For example, a keyring will return an array of
+.I key_serial_t
+entries representing the IDs of all the keys that are linked to it.
+The
+.I user
+key type will return its data as is.
+If a key type does not implement this function,
+the operation fails with the error
+.BR EOPNOTSUPP .
+.IP
+If
+.I arg3
+is not NULL,
+as much of the payload data as will fit is copied into the buffer.
+On a successful return,
+the return value is always the total size of the payload data.
+To determine whether the buffer was of sufficient size,
+check to see that the return value is less than or equal to
+the value supplied in
+.IR arg4 .
+.IP
+The key must either grant the caller
+.I read
+permission, or grant the caller
+.I search
+permission when searched for from the process keyrings
+(i.e., the key is possessed).
+.IP
+The
+.I arg5
+argument is ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_read (3).
+.TP
+.BR KEYCTL_INSTANTIATE " (since Linux 2.6.10)"
+(Positively) instantiate an uninstantiated key with a specified payload.
+.IP
+The ID of the key to be instantiated is provided in
+.I arg2
+(cast to
+.IR key_serial_t ).
+.IP
+The key payload is specified in the buffer pointed to by
+.I arg3
+(cast to
+.IR "void\ *");
+the size of that buffer is specified in
+.I arg4
+(cast to
+.IR size_t ).
+.IP
+The payload may be a null pointer and the buffer size may be 0
+if this is supported by the key type (e.g., it is a keyring).
+.IP
+The operation may be fail if the payload data is in the wrong format
+or is otherwise invalid.
+.IP
+If
+.I arg5
+(cast to
+.IR key_serial_t )
+is nonzero, then, subject to the same constraints and rules as
+.BR KEYCTL_LINK ,
+the instantiated key is linked into the keyring whose ID specified in
+.IR arg5 .
+.IP
+The caller must have the appropriate authorization key,
+and once the uninstantiated key has been instantiated,
+the authorization key is revoked.
+In other words, this operation is available only from a
+.BR request\-key (8)-style
+program.
+See
+.BR request_key (2)
+for an explanation of uninstantiated keys and key instantiation.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_instantiate (3).
+.TP
+.BR KEYCTL_NEGATE " (since Linux 2.6.10)"
+Negatively instantiate an uninstantiated key.
+.IP
+This operation is equivalent to the call:
+.IP
+.in +4n
+.EX
+keyctl(KEYCTL_REJECT, arg2, arg3, ENOKEY, arg4);
+.EE
+.in
+.IP
+The
+.I arg5
+argument is ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_negate (3).
+.TP
+.BR KEYCTL_SET_REQKEY_KEYRING " (since Linux 2.6.13)"
+Set the default keyring to which implicitly requested keys
+will be linked for this thread, and return the previous setting.
+Implicit key requests are those made by internal kernel components,
+.\" I.e., calls to the kernel's internal request_key() interface,
+.\" which is distinct from the request_key(2) system call (which
+.\" ultimately employs the kernel-internal interface).
+such as can occur when, for example, opening files
+on an AFS or NFS filesystem.
+Setting the default keyring also has an effect when requesting
+a key from user space; see
+.BR request_key (2)
+for details.
+.IP
+The
+.I arg2
+argument (cast to
+.IR int )
+should contain one of the following values,
+to specify the new default keyring:
+.RS
+.TP
+.B KEY_REQKEY_DEFL_NO_CHANGE
+Don't change the default keyring.
+This can be used to discover the current default keyring
+(without changing it).
+.TP
+.B KEY_REQKEY_DEFL_DEFAULT
+This selects the default behaviour,
+which is to use the thread-specific keyring if there is one,
+otherwise the process-specific keyring if there is one,
+otherwise the session keyring if there is one,
+otherwise the UID-specific session keyring,
+otherwise the user-specific keyring.
+.TP
+.B KEY_REQKEY_DEFL_THREAD_KEYRING
+Use the thread-specific keyring
+.RB ( thread\-keyring (7))
+as the new default keyring.
+.TP
+.B KEY_REQKEY_DEFL_PROCESS_KEYRING
+Use the process-specific keyring
+.RB ( process\-keyring (7))
+as the new default keyring.
+.TP
+.B KEY_REQKEY_DEFL_SESSION_KEYRING
+Use the session-specific keyring
+.RB ( session\-keyring (7))
+as the new default keyring.
+.TP
+.B KEY_REQKEY_DEFL_USER_KEYRING
+Use the UID-specific keyring
+.RB ( user\-keyring (7))
+as the new default keyring.
+.TP
+.B KEY_REQKEY_DEFL_USER_SESSION_KEYRING
+Use the UID-specific session keyring
+.RB ( user\-session\-keyring (7))
+as the new default keyring.
+.TP
+.BR KEY_REQKEY_DEFL_REQUESTOR_KEYRING " (since Linux 2.6.29)"
+.\" 8bbf4976b59fc9fc2861e79cab7beb3f6d647640
+Use the requestor keyring.
+.\" FIXME The preceding explanation needs to be expanded.
+.\" Is the following correct:
+.\"
+.\"	The requestor keyring is the dest_keyring that
+.\"	was supplied to a call to request_key(2)?
+.\"
+.\" David Howells said: to be checked
+.RE
+.IP
+All other values are invalid.
+.\" (including the still-unsupported KEY_REQKEY_DEFL_GROUP_KEYRING)
+.IP
+The arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+The setting controlled by this operation is inherited by the child of
+.BR fork (2)
+and preserved across
+.BR  execve (2).
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_set_reqkey_keyring (3).
+.TP
+.BR KEYCTL_SET_TIMEOUT " (since Linux 2.6.16)"
+Set a timeout on a key.
+.IP
+The ID of the key is specified in
+.I arg2
+(cast to
+.IR key_serial_t ).
+The timeout value, in seconds from the current time,
+is specified in
+.I arg3
+(cast to
+.IR "unsigned int" ).
+The timeout is measured against the realtime clock.
+.IP
+Specifying the timeout value as 0 clears any existing timeout on the key.
+.IP
+The
+.I /proc/keys
+file displays the remaining time until each key will expire.
+(This is the only method of discovering the timeout on a key.)
+.IP
+The caller must either have the
+.I setattr
+permission on the key
+or hold an instantiation authorization token for the key (see
+.BR request_key (2)).
+.IP
+The key and any links to the key will be
+automatically garbage collected after the timeout expires.
+Subsequent attempts to access the key will then fail with the error
+.BR EKEYEXPIRED .
+.IP
+This operation cannot be used to set timeouts on revoked, expired,
+or negatively instantiated keys.
+.IP
+The arguments
+.I arg4
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_set_timeout (3).
+.TP
+.BR KEYCTL_ASSUME_AUTHORITY " (since Linux 2.6.16)"
+Assume (or divest) the authority for the calling thread
+to instantiate a key.
+.IP
+The
+.I arg2
+argument (cast to
+.IR key_serial_t )
+specifies either a nonzero key ID to assume authority,
+or the value 0 to divest authority.
+.IP
+If
+.I arg2
+is nonzero, then it specifies the ID of an uninstantiated key for which
+authority is to be assumed.
+That key can then be instantiated using one of
+.BR KEYCTL_INSTANTIATE ,
+.BR KEYCTL_INSTANTIATE_IOV ,
+.BR KEYCTL_REJECT ,
+or
+.BR KEYCTL_NEGATE .
+Once the key has been instantiated,
+the thread is automatically divested of authority to instantiate the key.
+.IP
+Authority over a key can be assumed only if the calling thread has present
+in its keyrings the authorization key that is
+associated with the specified key.
+(In other words, the
+.B KEYCTL_ASSUME_AUTHORITY
+operation is available only from a
+.BR request\-key (8)-style
+program; see
+.BR request_key (2)
+for an explanation of how this operation is used.)
+The caller must have
+.I search
+permission on the authorization key.
+.IP
+If the specified key has a matching authorization key,
+then the ID of that key is returned.
+The authorization key can be read
+.RB ( KEYCTL_READ )
+to obtain the callout information passed to
+.BR request_key (2).
+.IP
+If the ID given in
+.I arg2
+is 0, then the currently assumed authority is cleared (divested),
+and the value 0 is returned.
+.IP
+The
+.B KEYCTL_ASSUME_AUTHORITY
+mechanism allows a program such as
+.BR request\-key (8)
+to assume the necessary authority to instantiate a new uninstantiated key
+that was created as a consequence of a call to
+.BR request_key (2).
+For further information, see
+.BR request_key (2)
+and the kernel source file
+.IR Documentation/security/keys\-request\-key.txt .
+.IP
+The arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_assume_authority (3).
+.TP
+.BR KEYCTL_GET_SECURITY " (since Linux 2.6.26)"
+.\" commit 70a5bb72b55e82fbfbf1e22cae6975fac58a1e2d
+Get the LSM (Linux Security Module) security label of the specified key.
+.IP
+The ID of the key whose security label is to be fetched is specified in
+.I arg2
+(cast to
+.IR key_serial_t ).
+The security label (terminated by a null byte)
+will be placed in the buffer pointed to by
+.I arg3
+argument (cast to
+.IR "char\ *" );
+the size of the buffer must be provided in
+.I arg4
+(cast to
+.IR size_t ).
+.IP
+If
+.I arg3
+is specified as NULL or the buffer size specified in
+.I arg4
+is too small, the full size of the security label string
+(including the terminating null byte)
+is returned as the function result,
+and nothing is copied to the buffer.
+.IP
+The caller must have
+.I view
+permission on the specified key.
+.IP
+The returned security label string will be rendered in a form appropriate
+to the LSM in force.
+For example, with SELinux, it may look like:
+.IP
+.in +4n
+.EX
+unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
+.EE
+.in
+.IP
+If no LSM is currently in force,
+then an empty string is placed in the buffer.
+.IP
+The
+.I arg5
+argument is ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the functions
+.BR keyctl_get_security (3)
+and
+.BR keyctl_get_security_alloc (3).
+.TP
+.BR KEYCTL_SESSION_TO_PARENT " (since Linux 2.6.32)"
+.\" commit ee18d64c1f632043a02e6f5ba5e045bb26a5465f
+Replace the session keyring to which the
+.I parent
+of the calling process
+subscribes with the session keyring of the calling process.
+.\" What is the use case for KEYCTL_SESSION_TO_PARENT?
+.\" David Howells: the Process Authentication Groups people requested this,
+.\" but then didn't use it; maybe there are no users.
+.IP
+The keyring will be replaced in the parent process at the point
+where the parent next transitions from kernel space to user space.
+.IP
+The keyring must exist and must grant the caller
+.I link
+permission.
+The parent process must be single-threaded and have
+the same effective ownership as this process
+and must not be set-user-ID or set-group-ID.
+The UID of the parent process's existing session keyring (f it has one),
+as well as the UID of the caller's session keyring
+much match the caller's effective UID.
+.IP
+The fact that it is the parent process that is affected by this operation
+allows a program such as the shell to start a child process that
+uses this operation to change the shell's session keyring.
+(This is what the
+.BR keyctl (1)
+.B new_session
+command does.)
+.IP
+The arguments
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_session_to_parent (3).
+.TP
+.BR KEYCTL_REJECT " (since Linux 2.6.39)"
+.\" commit fdd1b94581782a2ddf9124414e5b7a5f48ce2f9c
+Mark a key as negatively instantiated and set an expiration timer
+on the key.
+This operation provides a superset of the functionality of the earlier
+.B KEYCTL_NEGATE
+operation.
+.IP
+The ID of the key that is to be negatively instantiated is specified in
+.I arg2
+(cast to
+.IR key_serial_t ).
+The
+.I arg3
+(cast to
+.IR "unsigned int" )
+argument specifies the lifetime of the key, in seconds.
+The
+.I arg4
+argument (cast to
+.IR "unsigned int" )
+specifies the error to be returned when a search hits this key;
+typically, this is one of
+.BR EKEYREJECTED ,
+.BR EKEYREVOKED ,
+or
+.BR EKEYEXPIRED .
+.IP
+If
+.I arg5
+(cast to
+.IR key_serial_t )
+is nonzero, then, subject to the same constraints and rules as
+.BR KEYCTL_LINK ,
+the negatively instantiated key is linked into the keyring
+whose ID is specified in
+.IR arg5 .
+.IP
+The caller must have the appropriate authorization key.
+In other words, this operation is available only from a
+.BR request\-key (8)-style
+program.
+See
+.BR request_key (2).
+.IP
+The caller must have the appropriate authorization key,
+and once the uninstantiated key has been instantiated,
+the authorization key is revoked.
+In other words, this operation is available only from a
+.BR request\-key (8)-style
+program.
+See
+.BR request_key (2)
+for an explanation of uninstantiated keys and key instantiation.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_reject (3).
+.TP
+.BR KEYCTL_INSTANTIATE_IOV " (since Linux 2.6.39)"
+.\" commit ee009e4a0d4555ed522a631bae9896399674f063
+Instantiate an uninstantiated key with a payload specified
+via a vector of buffers.
+.IP
+This operation is the same as
+.BR KEYCTL_INSTANTIATE ,
+but the payload data is specified as an array of
+.I iovec
+structures (see
+.BR iovec (3type)).
+.IP
+The pointer to the payload vector is specified in
+.I arg3
+(cast as
+.IR "const struct iovec\~*" ).
+The number of items in the vector is specified in
+.I arg4
+(cast as
+.IR "unsigned int" ).
+.IP
+The
+.I arg2
+(key ID)
+and
+.I arg5
+(keyring ID)
+are interpreted as for
+.BR KEYCTL_INSTANTIATE .
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_instantiate_iov (3).
+.TP
+.BR KEYCTL_INVALIDATE " (since Linux 3.5)"
+.\" commit fd75815f727f157a05f4c96b5294a4617c0557da
+Mark a key as invalid.
+.IP
+The ID of the key to be invalidated is specified in
+.I arg2
+(cast to
+.IR key_serial_t ).
+.IP
+To invalidate a key,
+the caller must have
+.I search
+permission on the key.
+.\" CAP_SYS_ADMIN is permitted to invalidate certain special keys
+.IP
+This operation marks the key as invalid
+and schedules immediate garbage collection.
+The garbage collector removes the invalidated key from all keyrings and
+deletes the key when its reference count reaches zero.
+After this operation,
+the key will be ignored by all searches,
+even if it is not yet deleted.
+.IP
+Keys that are marked invalid become invisible to normal key operations
+immediately, though they are still visible in
+.I /proc/keys
+(marked with an 'i' flag)
+until they are actually removed.
+.IP
+The arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_invalidate (3).
+.TP
+.BR KEYCTL_GET_PERSISTENT " (since Linux 3.13)"
+.\" commit f36f8c75ae2e7d4da34f4c908cebdb4aa42c977e
+Get the persistent keyring
+.RB ( persistent\-keyring (7))
+for a specified user and link it to a specified keyring.
+.IP
+The user ID is specified in
+.I arg2
+(cast to
+.IR uid_t ).
+If the value \-1 is specified, the caller's real user ID is used.
+The ID of the destination keyring is specified in
+.I arg3
+(cast to
+.IR key_serial_t ).
+.IP
+The caller must have the
+.B CAP_SETUID
+capability in its user namespace in order to fetch the persistent keyring
+for a user ID that does not match either the real or effective user ID
+of the caller.
+.IP
+If the call is successful,
+a link to the persistent keyring is added to the keyring
+whose ID was specified in
+.IR arg3 .
+.IP
+The caller must have
+.I write
+permission on the keyring.
+.IP
+The persistent keyring will be created by the kernel
+if it does not yet exist.
+.IP
+Each time the
+.B KEYCTL_GET_PERSISTENT
+operation is performed, the persistent keyring will
+have its expiration timeout reset to the value in:
+.IP
+.in +4n
+.EX
+/proc/sys/kernel/keys/persistent_keyring_expiry
+.EE
+.in
+.IP
+Should the timeout be reached,
+the persistent keyring will be removed and
+everything it pins can then be garbage collected.
+.IP
+Persistent keyrings were added in Linux 3.13.
+.IP
+The arguments
+.I arg4
+and
+.I arg5
+are ignored.
+.IP
+This operation is exposed by
+.I libkeyutils
+via the function
+.BR keyctl_get_persistent (3).
+.TP
+.BR KEYCTL_DH_COMPUTE " (since Linux 4.7)"
+.\" commit ddbb41148724367394d0880c516bfaeed127b52e
+Compute a Diffie-Hellman shared secret or public key,
+optionally applying key derivation function (KDF) to the result.
+.IP
+The
+.I arg2
+argument is a pointer to a set of parameters containing
+serial numbers for three
+.I \[dq]user\[dq]
+keys used in the Diffie-Hellman calculation,
+packaged in a structure of the following form:
+.IP
+.in +4n
+.EX
+struct keyctl_dh_params {
+    int32_t private; /* The local private key */
+    int32_t prime; /* The prime, known to both parties */
+    int32_t base;  /* The base integer: either a shared
+                      generator or the remote public key */
+};
+.EE
+.in
+.IP
+Each of the three keys specified in this structure must grant the caller
+.I read
+permission.
+The payloads of these keys are used to calculate the Diffie-Hellman
+result as:
+.IP
+.in +4n
+.EX
+base \[ha] private mod prime
+.EE
+.in
+.IP
+If the base is the shared generator, the result is the local public key.
+If the base is the remote public key, the result is the shared secret.
+.IP
+The
+.I arg3
+argument (cast to
+.IR char\~* )
+points to a buffer where the result of the calculation is placed.
+The size of that buffer is specified in
+.I arg4
+(cast to
+.IR size_t ).
+.IP
+The buffer must be large enough to accommodate the output data,
+otherwise an error is returned.
+If
+.I arg4
+is specified zero,
+in which case the buffer is not used and
+the operation returns the minimum required buffer size
+(i.e., the length of the prime).
+.IP
+Diffie-Hellman computations can be performed in user space,
+but require a multiple-precision integer (MPI) library.
+Moving the implementation into the kernel gives access to
+the kernel MPI implementation,
+and allows access to secure or acceleration hardware.
+.IP
+Adding support for DH computation to the
+.BR keyctl ()
+system call was considered a good fit due to the DH algorithm's use
+for deriving shared keys;
+it also allows the type of the key to determine
+which DH implementation (software or hardware) is appropriate.
+.\" commit f1c316a3ab9d24df6022682422fe897492f2c0c8
+.IP
+If the
+.I arg5
+argument is
+.BR NULL ,
+then the DH result itself is returned.
+Otherwise (since Linux 4.12), it is a pointer to a structure which specifies
+parameters of the KDF operation to be applied:
+.IP
+.in +4n
+.EX
+struct keyctl_kdf_params {
+    char *hashname;     /* Hash algorithm name */
+    char *otherinfo;    /* SP800\-56A OtherInfo */
+    __u32 otherinfolen; /* Length of otherinfo data */
+    __u32 __spare[8];   /* Reserved */
+};
+.EE
+.in
+.IP
+The
+.I hashname
+field is a null-terminated string which specifies a hash name
+(available in the kernel's crypto API; the list of the hashes available
+is rather tricky to observe; please refer to the
+.UR https://www.kernel.org\:/doc\:/html\:/latest\:/crypto\:/architecture.html
+"Kernel Crypto API Architecture"
+.UE
+documentation for the information regarding how hash names are constructed and
+your kernel's source and configuration regarding what ciphers
+and templates with type
+.B CRYPTO_ALG_TYPE_SHASH
+are available)
+to be applied to DH result in KDF operation.
+.IP
+The
+.I otherinfo
+field is an
+.I OtherInfo
+data as described in SP800-56A section 5.8.1.2 and is algorithm-specific.
+This data is concatenated with the result of DH operation and is provided as
+an input to the KDF operation.
+Its size is provided in the
+.I otherinfolen
+field and is limited by
+.B KEYCTL_KDF_MAX_OI_LEN
+constant that defined in
+.I security/keys/internal.h
+to a value of 64.
+.IP
+The
+.B __spare
+field is currently unused.
+.\" commit 4f9dabfaf8df971f8a3b6aa324f8f817be38d538
+It was ignored until Linux 4.13 (but still should be
+user-addressable since it is copied to the kernel),
+and should contain zeros since Linux 4.13.
+.IP
+The KDF implementation complies with SP800-56A as well
+as with SP800-108 (the counter KDF).
+.IP
+.\" keyutils commit 742c9d7b94051d3b21f9f61a73ed6b5f3544cb82
+.\" keyutils commit d68a981e5db41d059ac782071c35d1e8f3aaf61c
+This operation is exposed by
+.I libkeyutils
+(from
+.I libkeyutils
+1.5.10 onwards) via the functions
+.BR keyctl_dh_compute (3)
+and
+.BR keyctl_dh_compute_alloc (3).
+.TP
+.BR KEYCTL_RESTRICT_KEYRING " (since Linux 4.12)"
+.\" commit 6563c91fd645556c7801748f15bc727c77fcd311
+.\" commit 7228b66aaf723a623e578aa4db7d083bb39546c9
+Apply a key-linking restriction to the keyring with the ID provided in
+.I arg2
+(cast to
+.IR key_serial_t ).
+The caller must have
+.I setattr
+permission on the key.
+If
+.I arg3
+is NULL, any attempt to add a key to the keyring is blocked;
+otherwise it contains a pointer to a string with a key type name and
+.I arg4
+contains a pointer to string that describes the type-specific restriction.
+As of Linux 4.12, only the type "asymmetric" has restrictions defined:
+.RS
+.TP
+.B builtin_trusted
+Allows only keys that are signed by a key linked to the built-in keyring
+(".builtin_trusted_keys").
+.TP
+.B builtin_and_secondary_trusted
+Allows only keys that are signed by a key linked to the secondary keyring
+(".secondary_trusted_keys") or, by extension, a key in a built-in keyring,
+as the latter is linked to the former.
+.TP
+.BI key_or_keyring: key
+.TQ
+.BI key_or_keyring: key :chain
+If
+.I key
+specifies the ID of a key of type "asymmetric",
+then only keys that are signed by this key are allowed.
+.IP
+If
+.I key
+specifies the ID of a keyring,
+then only keys that are signed by a key linked
+to this keyring are allowed.
+.IP
+If ":chain" is specified, keys that are signed by a keys linked to the
+destination keyring (that is, the keyring with the ID specified in the
+.I arg2
+argument) are also allowed.
+.RE
+.IP
+Note that a restriction can be configured only once for the specified keyring;
+once a restriction is set, it can't be overridden.
+.IP
+The argument
+.I arg5
+is ignored.
+.\" FIXME Document KEYCTL_RESTRICT_KEYRING, added in Linux 4.12
+.\"     commit 6563c91fd645556c7801748f15bc727c77fcd311
+.\"     Author: Mat Martineau <mathew.j.martineau@linux.intel.com>
+.\" See Documentation/security/keys.txt
+.SH RETURN VALUE
+For a successful call, the return value depends on the operation:
+.TP
+.B KEYCTL_GET_KEYRING_ID
+The ID of the requested keyring.
+.TP
+.B KEYCTL_JOIN_SESSION_KEYRING
+The ID of the joined session keyring.
+.TP
+.B KEYCTL_DESCRIBE
+The size of the description (including the terminating null byte),
+irrespective of the provided buffer size.
+.TP
+.B KEYCTL_SEARCH
+The ID of the key that was found.
+.TP
+.B KEYCTL_READ
+The amount of data that is available in the key,
+irrespective of the provided buffer size.
+.TP
+.B KEYCTL_SET_REQKEY_KEYRING
+The ID of the previous default keyring
+to which implicitly requested keys were linked
+(one of
+.BR KEY_REQKEY_DEFL_USER_* ).
+.TP
+.B KEYCTL_ASSUME_AUTHORITY
+Either 0, if the ID given was 0,
+or the ID of the authorization key matching the specified key,
+if a nonzero key ID was provided.
+.TP
+.B KEYCTL_GET_SECURITY
+The size of the LSM security label string
+(including the terminating null byte),
+irrespective of the provided buffer size.
+.TP
+.B KEYCTL_GET_PERSISTENT
+The ID of the persistent keyring.
+.TP
+.B KEYCTL_DH_COMPUTE
+The number of bytes copied to the buffer, or, if
+.I arg4
+is 0, the required buffer size.
+.TP
+All other operations
+Zero.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The requested operation wasn't permitted.
+.TP
+.B EAGAIN
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and there was an error during crypto module initialization.
+.TP
+.B EDEADLK
+.I operation
+was
+.B KEYCTL_LINK
+and the requested link would result in a cycle.
+.TP
+.B EDEADLK
+.I operation
+was
+.B KEYCTL_RESTRICT_KEYRING
+and the requested keyring restriction would result in a cycle.
+.TP
+.B EDQUOT
+The key quota for the caller's user would be exceeded by creating a key or
+linking it to the keyring.
+.TP
+.B EEXIST
+.I operation
+was
+.B KEYCTL_RESTRICT_KEYRING
+and keyring provided in
+.I arg2
+argument already has a restriction set.
+.TP
+.B EFAULT
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and one of the following has failed:
+.RS
+.IP \[bu] 3
+copying of the
+.IR "struct keyctl_dh_params" ,
+provided in the
+.I arg2
+argument, from user space;
+.IP \[bu]
+copying of the
+.IR "struct keyctl_kdf_params" ,
+provided in the non-NULL
+.I arg5
+argument, from user space
+(in case kernel supports performing KDF operation on DH operation result);
+.IP \[bu]
+copying of data pointed by the
+.I hashname
+field of the
+.I "struct keyctl_kdf_params"
+from user space;
+.IP \[bu]
+copying of data pointed by the
+.I otherinfo
+field of the
+.I struct keyctl_kdf_params
+from user space if the
+.I otherinfolen
+field was nonzero;
+.IP \[bu]
+copying of the result to user space.
+.RE
+.TP
+.B EINVAL
+.I operation
+was
+.B KEYCTL_SETPERM
+and an invalid permission bit was specified in
+.IR arg3 .
+.TP
+.B EINVAL
+.I operation
+was
+.B KEYCTL_SEARCH
+and the size of the description in
+.I arg4
+(including the terminating null byte) exceeded 4096 bytes.
+.TP
+.B EINVAL
+size of the string (including the terminating null byte) specified in
+.I arg3
+(the key type)
+or
+.I arg4
+(the key description)
+exceeded the limit (32 bytes and 4096 bytes respectively).
+.TP
+.BR EINVAL " (before Linux 4.12)"
+.I operation
+was
+.BR KEYCTL_DH_COMPUTE ,
+argument
+.I arg5
+was non-NULL.
+.TP
+.B EINVAL
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+And the digest size of the hashing algorithm supplied is zero.
+.TP
+.B EINVAL
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and the buffer size provided is not enough to hold the result.
+Provide 0 as a buffer size in order to obtain the minimum buffer size.
+.TP
+.B EINVAL
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and the hash name provided in the
+.I hashname
+field of the
+.I struct keyctl_kdf_params
+pointed by
+.I arg5
+argument is too big (the limit is implementation-specific and varies between
+kernel versions, but it is deemed big enough for all valid algorithm names).
+.TP
+.B EINVAL
+.\" commit 4f9dabfaf8df971f8a3b6aa324f8f817be38d538
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and the
+.I __spare
+field of the
+.I struct keyctl_kdf_params
+provided in the
+.I arg5
+argument contains nonzero values.
+.TP
+.B EKEYEXPIRED
+An expired key was found or specified.
+.TP
+.B EKEYREJECTED
+A rejected key was found or specified.
+.TP
+.B EKEYREVOKED
+A revoked key was found or specified.
+.TP
+.B ELOOP
+.I operation
+was
+.B KEYCTL_LINK
+and the requested link would cause the maximum nesting depth
+for keyrings to be exceeded.
+.TP
+.B EMSGSIZE
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and the buffer length exceeds
+.B KEYCTL_KDF_MAX_OUTPUT_LEN
+(which is 1024 currently)
+or the
+.I otherinfolen
+field of the
+.I struct keyctl_kdf_parms
+passed in
+.I arg5
+exceeds
+.B KEYCTL_KDF_MAX_OI_LEN
+(which is 64 currently).
+.TP
+.BR ENFILE " (before Linux 3.13)"
+.I operation
+was
+.B KEYCTL_LINK
+and the keyring is full.
+(Before Linux 3.13,
+.\" commit b2a4df200d570b2c33a57e1ebfa5896e4bc81b69
+the available space for storing keyring links was limited to
+a single page of memory; since Linux 3.13, there is no fixed limit.)
+.TP
+.B ENOENT
+.I operation
+was
+.B KEYCTL_UNLINK
+and the key to be unlinked isn't linked to the keyring.
+.TP
+.B ENOENT
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and the hashing algorithm specified in the
+.I hashname
+field of the
+.I struct keyctl_kdf_params
+pointed by
+.I arg5
+argument hasn't been found.
+.TP
+.B ENOENT
+.I operation
+was
+.B KEYCTL_RESTRICT_KEYRING
+and the type provided in
+.I arg3
+argument doesn't support setting key linking restrictions.
+.TP
+.B ENOKEY
+No matching key was found or an invalid key was specified.
+.TP
+.B ENOKEY
+The value
+.B KEYCTL_GET_KEYRING_ID
+was specified in
+.IR operation ,
+the key specified in
+.I arg2
+did not exist, and
+.I arg3
+was zero (meaning don't create the key if it didn't exist).
+.TP
+.B ENOMEM
+One of kernel memory allocation routines failed during the execution of the
+syscall.
+.TP
+.B ENOTDIR
+A key of keyring type was expected but the ID of a key with
+a different type was provided.
+.TP
+.B EOPNOTSUPP
+.I operation
+was
+.B KEYCTL_READ
+and the key type does not support reading
+(e.g., the type is
+.IR \[dq]login\[dq] ).
+.TP
+.B EOPNOTSUPP
+.I operation
+was
+.B KEYCTL_UPDATE
+and the key type does not support updating.
+.TP
+.B EOPNOTSUPP
+.I operation
+was
+.BR KEYCTL_RESTRICT_KEYRING ,
+the type provided in
+.I arg3
+argument was "asymmetric",
+and the key specified in the restriction specification provided in
+.I arg4
+has type other than "asymmetric" or "keyring".
+.TP
+.B EPERM
+.I operation
+was
+.BR KEYCTL_GET_PERSISTENT ,
+.I arg2
+specified a UID other than the calling thread's real or effective UID,
+and the caller did not have the
+.B CAP_SETUID
+capability.
+.TP
+.B EPERM
+.I operation
+was
+.B KEYCTL_SESSION_TO_PARENT
+and either:
+all of the UIDs (GIDs) of the parent process do not match
+the effective UID (GID) of the calling process;
+the UID of the parent's existing session keyring or
+the UID of the caller's session keyring did not match
+the effective UID of the caller;
+the parent process is not single-thread;
+or the parent process is
+.BR init (1)
+or a kernel thread.
+.TP
+.B ETIMEDOUT
+.I operation
+was
+.B KEYCTL_DH_COMPUTE
+and the initialization of crypto modules has timed out.
+.SH VERSIONS
+A wrapper is provided in the
+.I libkeyutils
+library.
+(The accompanying package provides the
+.I <keyutils.h>
+header file.)
+However, rather than using this system call directly,
+you probably want to use the various library functions
+mentioned in the descriptions of individual operations above.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.10.
+.SH EXAMPLES
+The program below provide subset of the functionality of the
+.BR request\-key (8)
+program provided by the
+.I keyutils
+package.
+For informational purposes,
+the program records various information in a log file.
+.P
+As described in
+.BR request_key (2),
+the
+.BR request\-key (8)
+program is invoked with command-line arguments that
+describe a key that is to be instantiated.
+The example program fetches and logs these arguments.
+The program assumes authority to instantiate the requested key,
+and then instantiates that key.
+.P
+The following shell session demonstrates the use of this program.
+In the session,
+we compile the program and then use it to temporarily replace the standard
+.BR request\-key (8)
+program.
+(Note that temporarily disabling the standard
+.BR request\-key (8)
+program may not be safe on some systems.)
+While our example program is installed,
+we use the example program shown in
+.BR request_key (2)
+to request a key.
+.P
+.in +4n
+.EX
+$ \fBcc \-o key_instantiate key_instantiate.c \-lkeyutils\fP
+$ \fBsudo mv /sbin/request\-key /sbin/request\-key.backup\fP
+$ \fBsudo cp key_instantiate /sbin/request\-key\fP
+$ \fB./t_request_key user mykey somepayloaddata\fP
+Key ID is 20d035bf
+$ \fBsudo mv /sbin/request\-key.backup /sbin/request\-key\fP
+.EE
+.in
+.P
+Looking at the log file created by this program,
+we can see the command-line arguments supplied to our example program:
+.P
+.in +4n
+.EX
+$ \fBcat /tmp/key_instantiate.log\fP
+Time: Mon Nov  7 13:06:47 2016
+\&
+Command line arguments:
+  argv[0]:            /sbin/request\-key
+  operation:          create
+  key_to_instantiate: 20d035bf
+  UID:                1000
+  GID:                1000
+  thread_keyring:     0
+  process_keyring:    0
+  session_keyring:    256e6a6
+\&
+Key description:      user;1000;1000;3f010000;mykey
+Auth key payload:     somepayloaddata
+Destination keyring:  256e6a6
+Auth key description: .request_key_auth;1000;1000;0b010000;20d035bf
+.EE
+.in
+.P
+The last few lines of the above output show that the example program
+was able to fetch:
+.IP \[bu] 3
+the description of the key to be instantiated,
+which included the name of the key
+.RI ( mykey );
+.IP \[bu]
+the payload of the authorization key, which consisted of the data
+.RI ( somepayloaddata )
+passed to
+.BR request_key (2);
+.IP \[bu]
+the destination keyring that was specified in the call to
+.BR request_key (2);
+and
+.IP \[bu]
+the description of the authorization key,
+where we can see that the name of the authorization key matches
+the ID of the key that is to be instantiated
+.RI ( 20d035bf ).
+.P
+The example program in
+.BR request_key (2)
+specified the destination keyring as
+.BR KEY_SPEC_SESSION_KEYRING .
+By examining the contents of
+.IR /proc/keys ,
+we can see that this was translated to the ID of the destination keyring
+.RI ( 0256e6a6 )
+shown in the log output above;
+we can also see the newly created key with the name
+.I mykey
+and ID
+.IR 20d035bf .
+.P
+.in +4n
+.EX
+$ \fBcat /proc/keys | egrep \[aq]mykey|256e6a6\[aq]\fP
+0256e6a6 I\-\-Q\-\-\-  194 perm 3f030000  1000  1000 keyring  _ses: 3
+20d035bf I\-\-Q\-\-\-    1 perm 3f010000  1000  1000 user     mykey: 16
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (key_instantiate.c)
+.EX
+/* key_instantiate.c */
+\&
+#include <errno.h>
+#include <keyutils.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <time.h>
+\&
+#ifndef KEY_SPEC_REQUESTOR_KEYRING
+#define KEY_SPEC_REQUESTOR_KEYRING      (\-8)
+#endif
+\&
+int
+main(int argc, char *argv[])
+{
+    int           akp_size;       /* Size of auth_key_payload */
+    int           auth_key;
+    char          dbuf[256];
+    char          auth_key_payload[256];
+    char          *operation;
+    FILE          *fp;
+    gid_t         gid;
+    uid_t         uid;
+    time_t        t;
+    key_serial_t  key_to_instantiate, dest_keyring;
+    key_serial_t  thread_keyring, process_keyring, session_keyring;
+\&
+    if (argc != 8) {
+        fprintf(stderr, "Usage: %s op key uid gid thread_keyring "
+                        "process_keyring session_keyring\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fp = fopen("/tmp/key_instantiate.log", "w");
+    if (fp == NULL)
+        exit(EXIT_FAILURE);
+\&
+    setbuf(fp, NULL);
+\&
+    t = time(NULL);
+    fprintf(fp, "Time: %s\en", ctime(&t));
+\&
+    /*
+     * The kernel passes a fixed set of arguments to the program
+     * that it execs; fetch them.
+     */
+    operation = argv[1];
+    key_to_instantiate = atoi(argv[2]);
+    uid = atoi(argv[3]);
+    gid = atoi(argv[4]);
+    thread_keyring = atoi(argv[5]);
+    process_keyring = atoi(argv[6]);
+    session_keyring = atoi(argv[7]);
+\&
+    fprintf(fp, "Command line arguments:\en");
+    fprintf(fp, "  argv[0]:            %s\en", argv[0]);
+    fprintf(fp, "  operation:          %s\en", operation);
+    fprintf(fp, "  key_to_instantiate: %jx\en",
+            (uintmax_t) key_to_instantiate);
+    fprintf(fp, "  UID:                %jd\en", (intmax_t) uid);
+    fprintf(fp, "  GID:                %jd\en", (intmax_t) gid);
+    fprintf(fp, "  thread_keyring:     %jx\en",
+            (uintmax_t) thread_keyring);
+    fprintf(fp, "  process_keyring:    %jx\en",
+            (uintmax_t) process_keyring);
+    fprintf(fp, "  session_keyring:    %jx\en",
+            (uintmax_t) session_keyring);
+    fprintf(fp, "\en");
+\&
+    /*
+     * Assume the authority to instantiate the key named in argv[2].
+     */
+    if (keyctl(KEYCTL_ASSUME_AUTHORITY, key_to_instantiate) == \-1) {
+        fprintf(fp, "KEYCTL_ASSUME_AUTHORITY failed: %s\en",
+                strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Fetch the description of the key that is to be instantiated.
+     */
+    if (keyctl(KEYCTL_DESCRIBE, key_to_instantiate,
+               dbuf, sizeof(dbuf)) == \-1) {
+        fprintf(fp, "KEYCTL_DESCRIBE failed: %s\en", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    fprintf(fp, "Key description:      %s\en", dbuf);
+\&
+    /*
+     * Fetch the payload of the authorization key, which is
+     * actually the callout data given to request_key().
+     */
+    akp_size = keyctl(KEYCTL_READ, KEY_SPEC_REQKEY_AUTH_KEY,
+                      auth_key_payload, sizeof(auth_key_payload));
+    if (akp_size == \-1) {
+        fprintf(fp, "KEYCTL_READ failed: %s\en", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    auth_key_payload[akp_size] = \[aq]\e0\[aq];
+    fprintf(fp, "Auth key payload:     %s\en", auth_key_payload);
+\&
+    /*
+     * For interest, get the ID of the authorization key and
+     * display it.
+     */
+    auth_key = keyctl(KEYCTL_GET_KEYRING_ID,
+                      KEY_SPEC_REQKEY_AUTH_KEY);
+    if (auth_key == \-1) {
+        fprintf(fp, "KEYCTL_GET_KEYRING_ID failed: %s\en",
+                strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    fprintf(fp, "Auth key ID:          %jx\en", (uintmax_t) auth_key);
+\&
+    /*
+     * Fetch key ID for the request_key(2) destination keyring.
+     */
+    dest_keyring = keyctl(KEYCTL_GET_KEYRING_ID,
+                          KEY_SPEC_REQUESTOR_KEYRING);
+    if (dest_keyring == \-1) {
+        fprintf(fp, "KEYCTL_GET_KEYRING_ID failed: %s\en",
+                strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    fprintf(fp, "Destination keyring:  %jx\en", (uintmax_t) dest_keyring);
+\&
+    /*
+     * Fetch the description of the authorization key. This
+     * allows us to see the key type, UID, GID, permissions,
+     * and description (name) of the key. Among other things,
+     * we will see that the name of the key is a hexadecimal
+     * string representing the ID of the key to be instantiated.
+     */
+    if (keyctl(KEYCTL_DESCRIBE, KEY_SPEC_REQKEY_AUTH_KEY,
+               dbuf, sizeof(dbuf)) == \-1)
+    {
+        fprintf(fp, "KEYCTL_DESCRIBE failed: %s\en", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    fprintf(fp, "Auth key description: %s\en", dbuf);
+\&
+    /*
+     * Instantiate the key using the callout data that was supplied
+     * in the payload of the authorization key.
+     */
+    if (keyctl(KEYCTL_INSTANTIATE, key_to_instantiate,
+               auth_key_payload, akp_size + 1, dest_keyring) == \-1)
+    {
+        fprintf(fp, "KEYCTL_INSTANTIATE failed: %s\en",
+                strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR add_key (2),
+.BR request_key (2),
+.\"     .BR find_key_by_type_and_name (3)
+.\"     There is a man page, but this function seems not to exist
+.BR keyctl (3),
+.BR keyctl_assume_authority (3),
+.BR keyctl_chown (3),
+.BR keyctl_clear (3),
+.BR keyctl_describe (3),
+.BR keyctl_describe_alloc (3),
+.BR keyctl_dh_compute (3),
+.BR keyctl_dh_compute_alloc (3),
+.BR keyctl_get_keyring_ID (3),
+.BR keyctl_get_persistent (3),
+.BR keyctl_get_security (3),
+.BR keyctl_get_security_alloc (3),
+.BR keyctl_instantiate (3),
+.BR keyctl_instantiate_iov (3),
+.BR keyctl_invalidate (3),
+.BR keyctl_join_session_keyring (3),
+.BR keyctl_link (3),
+.BR keyctl_negate (3),
+.BR keyctl_read (3),
+.BR keyctl_read_alloc (3),
+.BR keyctl_reject (3),
+.BR keyctl_revoke (3),
+.BR keyctl_search (3),
+.BR keyctl_session_to_parent (3),
+.BR keyctl_set_reqkey_keyring (3),
+.BR keyctl_set_timeout (3),
+.BR keyctl_setperm (3),
+.BR keyctl_unlink (3),
+.BR keyctl_update (3),
+.BR recursive_key_scan (3),
+.BR recursive_session_key_scan (3),
+.BR capabilities (7),
+.BR credentials (7),
+.BR keyrings (7),
+.BR keyutils (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7),
+.BR user_namespaces (7),
+.BR user\-session\-keyring (7),
+.BR request\-key (8)
+.P
+The kernel source files under
+.I Documentation/security/keys/
+(or, before Linux 4.13, in the file
+.IR Documentation/security/keys.txt ).
diff --git a/man/man2/kill.2 b/man/man2/kill.2
new file mode 100644
index 000000000..16500fba2
--- /dev/null
+++ b/man/man2/kill.2
@@ -0,0 +1,165 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified by Thomas Koenig <ig25@rz.uni-karlsruhe.de>
+.\" Modified 1993-07-23 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1993-07-25 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-11-01 by Michael Haardt
+.\"  <michael@cantor.informatik.rwth-aachen.de>
+.\" Modified 1996-04-14 by Andries Brouwer <aeb@cwi.nl>
+.\"  [added some polishing contributed by Mike Battersby <mib@deakin.edu.au>]
+.\" Modified 1996-07-21 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 1997-01-17 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2001-12-18 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2002-07-24 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added note on historical rules enforced when an unprivileged process
+.\"	sends a signal.
+.\" Modified 2004-06-16 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added note on CAP_KILL
+.\" Modified 2004-06-24 by aeb
+.\" Modified, 2004-11-30, after idea from emmanuel.colbus@ensimag.imag.fr
+.\"
+.TH kill 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+kill \- send signal to a process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int kill(pid_t " pid ", int " sig );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR kill ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR kill ()
+system call
+can be used to send any signal to any process group or process.
+.P
+If \fIpid\fP is positive, then signal \fIsig\fP is sent to the
+process with the ID specified by \fIpid\fP.
+.P
+If \fIpid\fP equals 0, then \fIsig\fP is sent to every process in the
+process group of the calling process.
+.P
+If \fIpid\fP equals \-1, then \fIsig\fP is sent to every process
+for which the calling process has permission to send signals,
+except for process 1 (\fIinit\fP), but see below.
+.P
+If \fIpid\fP is less than \-1, then \fIsig\fP is sent to every process
+in the process group whose ID is \fI\-pid\fP.
+.P
+If \fIsig\fP is 0, then no signal is sent,
+but existence and permission checks are still performed;
+this can be used to check for the existence of a process ID or
+process group ID that the caller is permitted to signal.
+.P
+For a process to have permission to send a signal,
+it must either be privileged (under Linux: have the
+.B CAP_KILL
+capability in the user namespace of the target process),
+or the real or effective user ID of the sending process must equal
+the real or saved set-user-ID of the target process.
+In the case of
+.BR SIGCONT ,
+it suffices when the sending and receiving
+processes belong to the same session.
+(Historically, the rules were different; see NOTES.)
+.SH RETURN VALUE
+On success (at least one signal was sent), zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+An invalid signal was specified.
+.TP
+.B EPERM
+The calling process does not have permission to send the signal
+to any of the target processes.
+.TP
+.B ESRCH
+The target process or process group does not exist.
+Note that an existing process might be a zombie,
+a process that has terminated execution, but
+has not yet been
+.BR wait (2)ed
+for.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SS Linux notes
+Across different kernel versions, Linux has enforced different rules
+for the permissions required for an unprivileged process
+to send a signal to another process.
+.\" In the 0.* kernels things chopped and changed quite
+.\" a bit - MTK, 24 Jul 02
+In Linux 1.0 to 1.2.2, a signal could be sent if the
+effective user ID of the sender matched effective user ID of the target,
+or the real user ID of the sender matched the real user ID of the target.
+From Linux 1.2.3 until 1.3.77, a signal could be sent if the
+effective user ID of the sender matched either the real or effective
+user ID of the target.
+The current rules, which conform to POSIX.1, were adopted
+in Linux 1.3.78.
+.SH NOTES
+The only signals that can be sent to process ID 1, the
+.I init
+process, are those for which
+.I init
+has explicitly installed signal handlers.
+This is done to assure the
+system is not brought down accidentally.
+.P
+POSIX.1 requires that \fIkill(\-1,sig)\fP send \fIsig\fP
+to all processes that the calling process may send signals to,
+except possibly for some implementation-defined system processes.
+Linux allows a process to signal itself, but on Linux the call
+\fIkill(\-1,sig)\fP does not signal the calling process.
+.P
+POSIX.1 requires that if a process sends a signal to itself,
+and the sending thread does not have the signal blocked,
+and no other thread
+has it unblocked or is waiting for it in
+.BR sigwait (3),
+at least one
+unblocked signal must be delivered to the sending thread before the
+.BR kill ()
+returns.
+.SH BUGS
+In Linux 2.6 up to and including Linux 2.6.7,
+there was a bug that meant that when sending signals to a process group,
+.BR kill ()
+failed with the error
+.B EPERM
+if the caller did not have permission to send the signal to \fIany\fP (rather
+than \fIall\fP) of the members of the process group.
+Notwithstanding this error return, the signal was still delivered
+to all of the processes for which the caller had permission to signal.
+.SH SEE ALSO
+.BR kill (1),
+.BR _exit (2),
+.BR pidfd_send_signal (2),
+.BR signal (2),
+.BR tkill (2),
+.BR exit (3),
+.BR killpg (3),
+.BR sigqueue (3),
+.BR capabilities (7),
+.BR credentials (7),
+.BR signal (7)
diff --git a/man/man2/landlock_add_rule.2 b/man/man2/landlock_add_rule.2
new file mode 100644
index 000000000..4b95afb07
--- /dev/null
+++ b/man/man2/landlock_add_rule.2
@@ -0,0 +1,131 @@
+.\" Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
+.\" Copyright © 2019-2020 ANSSI
+.\" Copyright © 2021 Microsoft Corporation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH landlock_add_rule 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+landlock_add_rule \- add a new Landlock rule to a ruleset
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/landlock.h>" "  /* Definition of " LANDLOCK_* " constants */"
+.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
+.P
+.BI "int syscall(SYS_landlock_add_rule, int " ruleset_fd ,
+.BI "            enum landlock_rule_type " rule_type ,
+.BI "            const void *" rule_attr ", uint32_t " flags );
+.fi
+.SH DESCRIPTION
+A Landlock rule describes an action on an object.
+An object is currently a file hierarchy,
+and the related filesystem actions
+are defined with a set of access rights.
+This
+.BR landlock_add_rule ()
+system call enables adding a new Landlock rule to an existing ruleset
+created with
+.BR landlock_create_ruleset (2).
+See
+.BR landlock (7)
+for a global overview.
+.P
+.I ruleset_fd
+is a Landlock ruleset file descriptor obtained with
+.BR landlock_create_ruleset (2).
+.P
+.I rule_type
+identifies the structure type pointed to by
+.IR rule_attr .
+Currently, Linux supports the following
+.I rule_type
+value:
+.TP
+.B LANDLOCK_RULE_PATH_BENEATH
+This defines the object type as a file hierarchy.
+In this case,
+.I rule_attr
+points to the following structure:
+.IP
+.in +4n
+.EX
+struct landlock_path_beneath_attr {
+    __u64 allowed_access;
+    __s32 parent_fd;
+} __attribute__((packed));
+.EE
+.in
+.IP
+.I allowed_access
+contains a bitmask of allowed filesystem actions for this file hierarchy
+(see
+.B Filesystem actions
+in
+.BR landlock (7)).
+.IP
+.I parent_fd
+is an opened file descriptor, preferably with the
+.I O_PATH
+flag,
+which identifies the parent directory of the file hierarchy or
+just a file.
+.P
+.I flags
+must be 0.
+.SH RETURN VALUE
+On success,
+.BR landlock_add_rule ()
+returns 0.
+.SH ERRORS
+.BR landlock_add_rule ()
+can fail for the following reasons:
+.TP
+.B EOPNOTSUPP
+Landlock is supported by the kernel but disabled at boot time.
+.TP
+.B EINVAL
+.I flags
+is not 0, or the rule accesses are inconsistent (i.e.,
+.I rule_attr\->allowed_access
+is not a subset of the ruleset handled accesses).
+.TP
+.B ENOMSG
+Empty accesses (i.e.,
+.I rule_attr\->allowed_access
+is 0).
+.TP
+.B EBADF
+.I ruleset_fd
+is not a file descriptor for the current thread,
+or a member of
+.I rule_attr
+is not a file descriptor as expected.
+.TP
+.B EBADFD
+.I ruleset_fd
+is not a ruleset file descriptor,
+or a member of
+.I rule_attr
+is not the expected file descriptor type.
+.TP
+.B EPERM
+.I ruleset_fd
+has no write access to the underlying ruleset.
+.TP
+.B EFAULT
+.I rule_attr
+was not a valid address.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.13.
+.SH EXAMPLES
+See
+.BR landlock (7).
+.SH SEE ALSO
+.BR landlock_create_ruleset (2),
+.BR landlock_restrict_self (2),
+.BR landlock (7)
diff --git a/man/man2/landlock_create_ruleset.2 b/man/man2/landlock_create_ruleset.2
new file mode 100644
index 000000000..e62a3f9b9
--- /dev/null
+++ b/man/man2/landlock_create_ruleset.2
@@ -0,0 +1,124 @@
+.\" Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
+.\" Copyright © 2019-2020 ANSSI
+.\" Copyright © 2021 Microsoft Corporation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH landlock_create_ruleset 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+landlock_create_ruleset \- create a new Landlock ruleset
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/landlock.h>" "  /* Definition of " LANDLOCK_* " constants */"
+.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
+.P
+.B int syscall(SYS_landlock_create_ruleset,
+.BI "            const struct landlock_ruleset_attr *" attr ,
+.BI "            size_t " size " , uint32_t " flags );
+.fi
+.SH DESCRIPTION
+A Landlock ruleset identifies a set of rules (i.e., actions on objects).
+This
+.BR landlock_create_ruleset ()
+system call enables creating a new file descriptor identifying a ruleset.
+This file descriptor can then be used by
+.BR landlock_add_rule (2)
+and
+.BR landlock_restrict_self (2).
+See
+.BR landlock (7)
+for a global overview.
+.P
+.I attr
+specifies the properties of the new ruleset.
+It points to the following structure:
+.IP
+.in +4n
+.EX
+struct landlock_ruleset_attr {
+    __u64 handled_access_fs;
+};
+.EE
+.in
+.IP
+.I handled_access_fs
+is a bitmask of actions that is handled by this ruleset and
+should then be forbidden if no rule explicitly allows them
+(see
+.B Filesystem actions
+in
+.BR landlock (7)).
+This enables simply restricting ambient rights
+(e.g., global filesystem access) and is needed for compatibility reasons.
+.P
+.I size
+must be specified as
+.I sizeof(struct landlock_ruleset_attr)
+for compatibility reasons.
+.P
+.I flags
+must be 0 if
+.I attr
+is used.
+Otherwise,
+.I flags
+can be set to:
+.TP
+.B LANDLOCK_CREATE_RULESET_VERSION
+If
+.I attr
+is NULL and
+.I size
+is 0, then the returned value is the highest supported Landlock ABI version
+(starting at 1).
+This version can be used for a best-effort security approach,
+which is encouraged when user space is not pinned to a specific kernel
+version.
+All features documented in these man pages are available with the version
+1.
+.SH RETURN VALUE
+On success,
+.BR landlock_create_ruleset ()
+returns a new Landlock ruleset file descriptor,
+or a Landlock ABI version,
+according to
+.IR flags .
+.SH ERRORS
+.BR landlock_create_ruleset ()
+can fail for the following reasons:
+.TP
+.B EOPNOTSUPP
+Landlock is supported by the kernel but disabled at boot time.
+.TP
+.B EINVAL
+Unknown
+.IR flags ,
+or unknown access, or too small
+.IR size .
+.TP
+.B E2BIG
+.I size
+is too big.
+.TP
+.B EFAULT
+.I attr
+was not a valid address.
+.TP
+.B ENOMSG
+Empty accesses (i.e.,
+.I attr\->handled_access_fs
+is 0).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.13.
+.SH EXAMPLES
+See
+.BR landlock (7).
+.SH SEE ALSO
+.BR landlock_add_rule (2),
+.BR landlock_restrict_self (2),
+.BR landlock (7)
diff --git a/man/man2/landlock_restrict_self.2 b/man/man2/landlock_restrict_self.2
new file mode 100644
index 000000000..43f15c932
--- /dev/null
+++ b/man/man2/landlock_restrict_self.2
@@ -0,0 +1,116 @@
+.\" Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
+.\" Copyright © 2019-2020 ANSSI
+.\" Copyright © 2021 Microsoft Corporation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH landlock_restrict_self 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+landlock_restrict_self \- enforce a Landlock ruleset
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/landlock.h>" "  /* Definition of " LANDLOCK_* " constants */"
+.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
+.P
+.BI "int syscall(SYS_landlock_restrict_self, int " ruleset_fd ,
+.BI "            uint32_t " flags );
+.SH DESCRIPTION
+Once a Landlock ruleset is populated with the desired rules, the
+.BR landlock_restrict_self ()
+system call enables enforcing this ruleset on the calling thread.
+See
+.BR landlock (7)
+for a global overview.
+.P
+A thread can be restricted with multiple rulesets that are then
+composed together to form the thread's Landlock domain.
+This can be seen as a stack of rulesets but
+it is implemented in a more efficient way.
+A domain can only be updated in such a way that
+the constraints of each past and future composed rulesets
+will restrict the thread and its future children for their entire life.
+It is then possible to gradually enforce tailored access control policies
+with multiple independent rulesets coming from different sources
+(e.g., init system configuration, user session policy,
+built-in application policy).
+However, most applications should only need one call to
+.BR landlock_restrict_self ()
+and they should avoid arbitrary numbers of such calls because of the
+composed rulesets limit.
+Instead, developers are encouraged to build a tailored ruleset thanks to
+multiple calls to
+.BR landlock_add_rule (2).
+.P
+In order to enforce a ruleset, either the caller must have the
+.B CAP_SYS_ADMIN
+capability in its user namespace, or the thread must already have the
+.I no_new_privs
+bit set.
+As for
+.BR seccomp (2),
+this avoids scenarios where unprivileged processes can affect
+the behavior of privileged children (e.g., because of set-user-ID binaries).
+If that bit was not already set by an ancestor of this thread,
+the thread must make the following call:
+.IP
+.EX
+prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+.EE
+.P
+.I ruleset_fd
+is a Landlock ruleset file descriptor obtained with
+.BR landlock_create_ruleset (2)
+and fully populated with a set of calls to
+.BR landlock_add_rule (2).
+.P
+.I flags
+must be 0.
+.SH RETURN VALUE
+On success,
+.BR landlock_restrict_self ()
+returns 0.
+.SH ERRORS
+.BR landlock_restrict_self ()
+can fail for the following reasons:
+.TP
+.B EOPNOTSUPP
+Landlock is supported by the kernel but disabled at boot time.
+.TP
+.B EINVAL
+.I flags
+is not 0.
+.TP
+.B EBADF
+.I ruleset_fd
+is not a file descriptor for the current thread.
+.TP
+.B EBADFD
+.I ruleset_fd
+is not a ruleset file descriptor.
+.TP
+.B EPERM
+.I ruleset_fd
+has no read access to the underlying ruleset,
+or the calling thread is not running with
+.IR no_new_privs ,
+or it doesn't have the
+.B CAP_SYS_ADMIN
+in its user namespace.
+.TP
+.B E2BIG
+The maximum number of composed rulesets is reached for the calling thread.
+This limit is currently 64.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.13.
+.SH EXAMPLES
+See
+.BR landlock (7).
+.SH SEE ALSO
+.BR landlock_create_ruleset (2),
+.BR landlock_add_rule (2),
+.BR landlock (7)
diff --git a/man/man2/lchown.2 b/man/man2/lchown.2
new file mode 100644
index 000000000..f0a5635ae
--- /dev/null
+++ b/man/man2/lchown.2
@@ -0,0 +1 @@
+.so man2/chown.2
diff --git a/man/man2/lchown32.2 b/man/man2/lchown32.2
new file mode 100644
index 000000000..8ed3964e0
--- /dev/null
+++ b/man/man2/lchown32.2
@@ -0,0 +1 @@
+.so man2/lchown.2
diff --git a/man/man2/lgetxattr.2 b/man/man2/lgetxattr.2
new file mode 100644
index 000000000..d9e5d9037
--- /dev/null
+++ b/man/man2/lgetxattr.2
@@ -0,0 +1 @@
+.so man2/getxattr.2
diff --git a/man/man2/link.2 b/man/man2/link.2
new file mode 100644
index 000000000..576b5510b
--- /dev/null
+++ b/man/man2/link.2
@@ -0,0 +1,425 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\" and Copyright (C) 2006, 2014 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-23 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1994-08-21 by Michael Haardt
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2005-04-04, as per suggestion by Michael Hardt for rename.2
+.\"
+.TH link 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+link, linkat \- make a new name for a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int link(const char *" oldpath ", const char *" newpath );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of " AT_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int linkat(int " olddirfd ", const char *" oldpath ,
+.BI "           int " newdirfd ", const char *" newpath ", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR linkat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+.BR link ()
+creates a new link (also known as a hard link) to an existing file.
+.P
+If
+.I newpath
+exists, it will
+.I not
+be overwritten.
+.P
+This new name may be used exactly as the old one for any operation;
+both names refer to the same file (and so have the same permissions
+and ownership) and it is impossible to tell which name was the
+"original".
+.SS linkat()
+The
+.BR linkat ()
+system call operates in exactly the same way as
+.BR link (),
+except for the differences described here.
+.P
+If the pathname given in
+.I oldpath
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I olddirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR link ()
+for a relative pathname).
+.P
+If
+.I oldpath
+is relative and
+.I olddirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I oldpath
+is interpreted relative to the current working
+directory of the calling process (like
+.BR link ()).
+.P
+If
+.I oldpath
+is absolute, then
+.I olddirfd
+is ignored.
+.P
+The interpretation of
+.I newpath
+is as for
+.IR oldpath ,
+except that a relative pathname is interpreted relative
+to the directory referred to by the file descriptor
+.IR newdirfd .
+.P
+The following values can be bitwise ORed in
+.IR flags :
+.TP
+.BR AT_EMPTY_PATH " (since Linux 2.6.39)"
+.\" commit 11a7b371b64ef39fc5fb1b6f2218eef7c4d035e3
+If
+.I oldpath
+is an empty string, create a link to the file referenced by
+.I olddirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+In this case,
+.I olddirfd
+can refer to any type of file except a directory.
+This will generally not work if the file has a link count of zero (files
+created with
+.B O_TMPFILE
+and without
+.B O_EXCL
+are an exception).
+The caller must have the
+.B CAP_DAC_READ_SEARCH
+capability in order to use this flag.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.BR AT_SYMLINK_FOLLOW " (since Linux 2.6.18)"
+By default,
+.BR linkat (),
+does not dereference
+.I oldpath
+if it is a symbolic link (like
+.BR link ()).
+The flag
+.B AT_SYMLINK_FOLLOW
+can be specified in
+.I flags
+to cause
+.I oldpath
+to be dereferenced if it is a symbolic link.
+If procfs is mounted,
+this can be used as an alternative to
+.BR AT_EMPTY_PATH ,
+like this:
+.IP
+.in +4n
+.EX
+linkat(AT_FDCWD, "/proc/self/fd/<fd>", newdirfd,
+       newname, AT_SYMLINK_FOLLOW);
+.EE
+.in
+.P
+Before Linux 2.6.18, the
+.I flags
+argument was unused, and had to be specified as 0.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR linkat ().
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Write access to the directory containing
+.I newpath
+is denied, or search permission is denied for one of the directories
+in the path prefix of
+.I oldpath
+or
+.IR newpath .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EDQUOT
+The user's quota of disk blocks on the filesystem has been exhausted.
+.TP
+.B EEXIST
+.I newpath
+already exists.
+.TP
+.B EFAULT
+.IR oldpath " or " newpath " points outside your accessible address space."
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR oldpath " or " newpath .
+.TP
+.B EMLINK
+The file referred to by
+.I oldpath
+already has the maximum number of links to it.
+For example, on an
+.BR ext4 (5)
+filesystem that does not employ the
+.I dir_index
+feature, the limit on the number of hard links to a file is 65,000; on
+.BR btrfs (5),
+the limit is 65,535 links.
+.TP
+.B ENAMETOOLONG
+.IR oldpath " or " newpath " was too long."
+.TP
+.B ENOENT
+A directory component in
+.IR oldpath " or " newpath
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSPC
+The device containing the file has no room for the new directory
+entry.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.IR oldpath " or " newpath
+is not, in fact, a directory.
+.TP
+.B EPERM
+.I oldpath
+is a directory.
+.TP
+.B EPERM
+The filesystem containing
+.IR oldpath " and " newpath
+does not support the creation of hard links.
+.TP
+.BR EPERM " (since Linux 3.6)"
+The caller does not have permission to create a hard link to this file
+(see the description of
+.I /proc/sys/fs/protected_hardlinks
+in
+.BR proc (5)).
+.TP
+.B EPERM
+.I oldpath
+is marked immutable or append-only.
+(See
+.BR ioctl_iflags (2).)
+.TP
+.B EROFS
+The file is on a read-only filesystem.
+.TP
+.B EXDEV
+.IR oldpath " and " newpath
+are not on the same mounted filesystem.
+(Linux permits a filesystem to be mounted at multiple points, but
+.BR link ()
+does not work across different mounts,
+even if the same filesystem is mounted on both.)
+.P
+The following additional errors can occur for
+.BR linkat ():
+.TP
+.B EBADF
+.I oldpath
+.RI ( newpath )
+is relative but
+.I olddirfd
+.RI ( newdirfd )
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EINVAL
+An invalid flag value was specified in
+.IR flags .
+.TP
+.B ENOENT
+.B AT_EMPTY_PATH
+was specified in
+.IR flags ,
+but the caller did not have the
+.B CAP_DAC_READ_SEARCH
+capability.
+.TP
+.B ENOENT
+An attempt was made to link to the
+.I /proc/self/fd/NN
+file corresponding to a file descriptor created with
+.IP
+.in +4n
+.EX
+open(path, O_TMPFILE | O_EXCL, mode);
+.EE
+.in
+.IP
+See
+.BR open (2).
+.TP
+.B ENOENT
+An attempt was made to link to a
+.I /proc/self/fd/NN
+file corresponding to a file that has been deleted.
+.TP
+.B ENOENT
+.I oldpath
+is a relative pathname and
+.I olddirfd
+refers to a directory that has been deleted,
+or
+.I newpath
+is a relative pathname and
+.I newdirfd
+refers to a directory that has been deleted.
+.TP
+.B ENOTDIR
+.I oldpath
+is relative and
+.I olddirfd
+is a file descriptor referring to a file other than a directory;
+or similar for
+.I newpath
+and
+.I newdirfd
+.TP
+.B EPERM
+.B AT_EMPTY_PATH
+was specified in
+.IR flags ,
+.I oldpath
+is an empty string, and
+.I olddirfd
+refers to a directory.
+.SH VERSIONS
+POSIX.1-2001 says that
+.BR link ()
+should dereference
+.I oldpath
+if it is a symbolic link.
+However, since Linux 2.0,
+.\" more precisely: since Linux 1.3.56
+Linux does not do so: if
+.I oldpath
+is a symbolic link, then
+.I newpath
+is created as a (hard) link to the same symbolic link file
+(i.e.,
+.I newpath
+becomes a symbolic link to the same file that
+.I oldpath
+refers to).
+Some other implementations behave in the same manner as Linux.
+.\" For example, the default Solaris compilation environment
+.\" behaves like Linux, and contributors to a March 2005
+.\" thread in the Austin mailing list reported that some
+.\" other (System V) implementations did/do the same -- MTK, Apr 05
+POSIX.1-2008 changes the specification of
+.BR link (),
+making it implementation-dependent whether or not
+.I oldpath
+is dereferenced if it is a symbolic link.
+For precise control over the treatment of symbolic links when
+creating a link, use
+.BR linkat ().
+.SS glibc
+On older kernels where
+.BR linkat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR link (),
+unless the
+.B AT_SYMLINK_FOLLOW
+is specified.
+When
+.I oldpath
+and
+.I newpath
+are relative pathnames,
+glibc constructs pathnames based on the symbolic links in
+.I /proc/self/fd
+that correspond to the
+.I olddirfd
+and
+.I newdirfd
+arguments.
+.SH STANDARDS
+.TP
+.BR link ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR link ()
+SVr4, 4.3BSD, POSIX.1-2001 (but see VERSIONS).
+.\" SVr4 documents additional ENOLINK and
+.\" EMULTIHOP error conditions; POSIX.1 does not document ELOOP.
+.\" X/OPEN does not document EFAULT, ENOMEM or EIO.
+.TP
+.BR linkat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.SH NOTES
+Hard links, as created by
+.BR link (),
+cannot span filesystems.
+Use
+.BR symlink (2)
+if this is required.
+.SH BUGS
+On NFS filesystems, the return code may be wrong in case the NFS server
+performs the link creation and dies before it can say so.
+Use
+.BR stat (2)
+to find out if the link got created.
+.SH SEE ALSO
+.BR ln (1),
+.BR open (2),
+.BR rename (2),
+.BR stat (2),
+.BR symlink (2),
+.BR unlink (2),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/linkat.2 b/man/man2/linkat.2
new file mode 100644
index 000000000..a7d6da568
--- /dev/null
+++ b/man/man2/linkat.2
@@ -0,0 +1 @@
+.so man2/link.2
diff --git a/man/man2/listen.2 b/man/man2/listen.2
new file mode 100644
index 000000000..6ee5ad11a
--- /dev/null
+++ b/man/man2/listen.2
@@ -0,0 +1,155 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" and Copyright (C) 2007, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     $Id: listen.2,v 1.6 1999/05/18 14:10:32 freitag Exp $
+.\"
+.\" Modified Fri Jul 23 22:07:54 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 950727 by aeb, following a suggestion by Urs Thuermann
+.\" <urs@isnogud.escape.de>
+.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998 by Andi Kleen
+.\" Modified 11 May 2001 by Sam Varshavchik <mrsam@courier-mta.com>
+.\"
+.\"
+.TH listen 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+listen \- listen for connections on a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int listen(int " sockfd ", int " backlog );
+.fi
+.SH DESCRIPTION
+.BR listen ()
+marks the socket referred to by
+.I sockfd
+as a passive socket, that is, as a socket that will
+be used to accept incoming connection requests using
+.BR accept (2).
+.P
+The
+.I sockfd
+argument is a file descriptor that refers to a socket of type
+.B SOCK_STREAM
+or
+.BR SOCK_SEQPACKET .
+.P
+The
+.I backlog
+argument defines the maximum length
+to which the queue of pending connections for
+.I sockfd
+may grow.
+If a connection request arrives when the queue is full, the client
+may receive an error with an indication of
+.B ECONNREFUSED
+or, if the underlying protocol supports retransmission, the request may be
+ignored so that a later reattempt at connection succeeds.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EADDRINUSE
+Another socket is already listening on the same port.
+.TP
+.B EADDRINUSE
+(Internet domain sockets)
+The socket referred to by
+.I sockfd
+had not previously been bound to an address and,
+upon attempting to bind it to an ephemeral port,
+it was determined that all port numbers in the ephemeral port range
+are currently in use.
+See the discussion of
+.I /proc/sys/net/ipv4/ip_local_port_range
+in
+.BR ip (7).
+.TP
+.B EBADF
+The argument
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.TP
+.B EOPNOTSUPP
+The socket is not of a type that supports the
+.BR listen ()
+operation.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.4BSD
+(first appeared in 4.2BSD).
+.SH NOTES
+To accept connections, the following steps are performed:
+.RS 4
+.IP (1) 5
+A socket is created with
+.BR socket (2).
+.IP (2)
+The socket is bound to a local address using
+.BR bind (2),
+so that other sockets may be
+.BR connect (2)ed
+to it.
+.IP (3)
+A willingness to accept incoming connections and a queue limit for incoming
+connections are specified with
+.BR listen ().
+.IP (4)
+Connections are accepted with
+.BR accept (2).
+.RE
+.P
+The behavior of the
+.I backlog
+argument on TCP sockets changed with Linux 2.2.
+Now it specifies the queue length for
+.I completely
+established sockets waiting to be accepted,
+instead of the number of incomplete connection requests.
+The maximum length of the queue for incomplete sockets
+can be set using
+.IR /proc/sys/net/ipv4/tcp_max_syn_backlog .
+When syncookies are enabled there is no logical maximum
+length and this setting is ignored.
+See
+.BR tcp (7)
+for more information.
+.P
+If the
+.I backlog
+argument is greater than the value in
+.IR /proc/sys/net/core/somaxconn ,
+then it is silently capped to that value.
+Since Linux 5.4, the default in this file is 4096;
+in earlier kernels, the default value is 128.
+Before Linux 2.4.25, this limit was a hard coded value,
+.BR SOMAXCONN ,
+with the value 128.
+.\" The following is now rather historic information (MTK, Jun 05)
+.\" Don't rely on this value in portable applications since BSD
+.\" (and some BSD-derived systems) limit the backlog to 5.
+.SH EXAMPLES
+See
+.BR bind (2).
+.SH SEE ALSO
+.BR accept (2),
+.BR bind (2),
+.BR connect (2),
+.BR socket (2),
+.BR socket (7)
diff --git a/man/man2/listxattr.2 b/man/man2/listxattr.2
new file mode 100644
index 000000000..72b769a0e
--- /dev/null
+++ b/man/man2/listxattr.2
@@ -0,0 +1,322 @@
+.\" Copyright (C) Andreas Gruenbacher, February 2001
+.\" Copyright (C) Silicon Graphics Inc, September 2001
+.\" Copyright (C) 2015 Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH listxattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+listxattr, llistxattr, flistxattr \- list extended attribute names
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/xattr.h>
+.P
+.BI "ssize_t listxattr(const char *" path ", char *_Nullable " list \
+", size_t " size );
+.BI "ssize_t llistxattr(const char *" path ", char *_Nullable " list \
+", size_t " size );
+.BI "ssize_t flistxattr(int " fd ", char *_Nullable " list ", size_t " size );
+.fi
+.SH DESCRIPTION
+Extended attributes are
+.IR name : value
+pairs associated with inodes (files, directories, symbolic links, etc.).
+They are extensions to the normal attributes which are associated
+with all inodes in the system (i.e., the
+.BR stat (2)
+data).
+A complete overview of extended attributes concepts can be found in
+.BR xattr (7).
+.P
+.BR listxattr ()
+retrieves the list
+of extended attribute names associated with the given
+.I path
+in the filesystem.
+The retrieved list is placed in
+.IR list ,
+a caller-allocated buffer whose size (in bytes) is specified in the argument
+.IR size .
+The list is the set of (null-terminated) names, one after the other.
+Names of extended attributes to which the calling process does not
+have access may be omitted from the list.
+The length of the attribute name
+.I list
+is returned.
+.P
+.BR llistxattr ()
+is identical to
+.BR listxattr (),
+except in the case of a symbolic link, where the list of names of
+extended attributes associated with the link itself is retrieved,
+not the file that it refers to.
+.P
+.BR flistxattr ()
+is identical to
+.BR listxattr (),
+only the open file referred to by
+.I fd
+(as returned by
+.BR open (2))
+is interrogated in place of
+.IR path .
+.P
+A single extended attribute
+.I name
+is a null-terminated string.
+The name includes a namespace prefix; there may be several, disjoint
+namespaces associated with an individual inode.
+.P
+If
+.I size
+is specified as zero, these calls return the current size of the
+list of extended attribute names (and leave
+.I list
+unchanged).
+This can be used to determine the size of the buffer that
+should be supplied in a subsequent call.
+(But, bear in mind that there is a possibility that the
+set of extended attributes may change between the two calls,
+so that it is still necessary to check the return status
+from the second call.)
+.SS Example
+The
+.I list
+of names is returned as an unordered array of null-terminated character strings
+(attribute names are separated by null bytes (\[aq]\e0\[aq])),
+like this:
+.P
+.in +4n
+.EX
+user.name1\e0system.name1\e0user.name2\e0
+.EE
+.in
+.P
+Filesystems that implement POSIX ACLs using
+extended attributes might return a
+.I list
+like this:
+.P
+.in +4n
+.EX
+system.posix_acl_access\e0system.posix_acl_default\e0
+.EE
+.in
+.SH RETURN VALUE
+On success, a nonnegative number is returned indicating the size of the
+extended attribute name list.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B E2BIG
+The size of the list of extended attribute names is larger than the maximum
+size allowed; the list cannot be retrieved.
+This can happen on filesystems that support an unlimited number of
+extended attributes per file such as XFS, for example.
+See BUGS.
+.TP
+.B ENOTSUP
+Extended attributes are not supported by the filesystem, or are disabled.
+.TP
+.B ERANGE
+The
+.I size
+of the
+.I list
+buffer is too small to hold the result.
+.P
+In addition, the errors documented in
+.BR stat (2)
+can also occur.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.4,
+glibc 2.3.
+.\" .SH AUTHORS
+.\" Andreas Gruenbacher,
+.\" .RI < a.gruenbacher@computer.org >
+.\" and the SGI XFS development team,
+.\" .RI < linux-xfs@oss.sgi.com >.
+.\" Please send any bug reports or comments to these addresses.
+.SH BUGS
+.\" The xattr(7) page refers to this text:
+As noted in
+.BR xattr (7),
+the VFS imposes a limit of 64\ kB on the size of the extended
+attribute name list returned by
+.BR listxattr ().
+If the total size of attribute names attached to a file exceeds this limit,
+it is no longer possible to retrieve the list of attribute names.
+.SH EXAMPLES
+The following program demonstrates the usage of
+.BR listxattr ()
+and
+.BR getxattr (2).
+For the file whose pathname is provided as a command-line argument,
+it lists all extended file attributes and their values.
+.P
+To keep the code simple, the program assumes that attribute keys and
+values are constant during the execution of the program.
+A production program should expect and handle changes during
+execution of the program.
+For example,
+the number of bytes required for attribute keys
+might increase between the two calls to
+.BR listxattr ().
+An application could handle this possibility using
+a loop that retries the call
+(perhaps up to a predetermined maximum number of attempts)
+with a larger buffer each time it fails with the error
+.BR ERANGE .
+Calls to
+.BR getxattr (2)
+could be handled similarly.
+.P
+The following output was recorded by first creating a file, setting
+some extended file attributes,
+and then listing the attributes with the example program.
+.SS Example output
+.in +4n
+.EX
+$ \fBtouch /tmp/foo\fP
+$ \fBsetfattr \-n user.fred \-v chocolate /tmp/foo\fP
+$ \fBsetfattr \-n user.frieda \-v bar /tmp/foo\fP
+$ \fBsetfattr \-n user.empty /tmp/foo\fP
+$ \fB./listxattr /tmp/foo\fP
+user.fred: chocolate
+user.frieda: bar
+user.empty: <no value>
+.EE
+.in
+.SS Program source (listxattr.c)
+.\" SRC BEGIN (listxattr.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/xattr.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    char     *buf, *key, *val;
+    ssize_t  buflen, keylen, vallen;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s path\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Determine the length of the buffer needed.
+     */
+    buflen = listxattr(argv[1], NULL, 0);
+    if (buflen == \-1) {
+        perror("listxattr");
+        exit(EXIT_FAILURE);
+    }
+    if (buflen == 0) {
+        printf("%s has no attributes.\en", argv[1]);
+        exit(EXIT_SUCCESS);
+    }
+\&
+    /*
+     * Allocate the buffer.
+     */
+    buf = malloc(buflen);
+    if (buf == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Copy the list of attribute keys to the buffer.
+     */
+    buflen = listxattr(argv[1], buf, buflen);
+    if (buflen == \-1) {
+        perror("listxattr");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Loop over the list of zero terminated strings with the
+     * attribute keys. Use the remaining buffer length to determine
+     * the end of the list.
+     */
+    key = buf;
+    while (buflen > 0) {
+\&
+        /*
+         * Output attribute key.
+         */
+        printf("%s: ", key);
+\&
+        /*
+         * Determine length of the value.
+         */
+        vallen = getxattr(argv[1], key, NULL, 0);
+        if (vallen == \-1)
+            perror("getxattr");
+\&
+        if (vallen > 0) {
+\&
+            /*
+             * Allocate value buffer.
+             * One extra byte is needed to append 0x00.
+             */
+            val = malloc(vallen + 1);
+            if (val == NULL) {
+                perror("malloc");
+                exit(EXIT_FAILURE);
+            }
+\&
+            /*
+             * Copy value to buffer.
+             */
+            vallen = getxattr(argv[1], key, val, vallen);
+            if (vallen == \-1) {
+                perror("getxattr");
+            } else {
+                /*
+                 * Output attribute value.
+                 */
+                val[vallen] = 0;
+                printf("%s", val);
+            }
+\&
+            free(val);
+        } else if (vallen == 0) {
+            printf("<no value>");
+        }
+\&
+        printf("\en");
+\&
+        /*
+         * Forward to next attribute key.
+         */
+        keylen = strlen(key) + 1;
+        buflen \-= keylen;
+        key += keylen;
+    }
+\&
+    free(buf);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getfattr (1),
+.BR setfattr (1),
+.BR getxattr (2),
+.BR open (2),
+.BR removexattr (2),
+.BR setxattr (2),
+.BR stat (2),
+.BR symlink (7),
+.BR xattr (7)
diff --git a/man/man2/llistxattr.2 b/man/man2/llistxattr.2
new file mode 100644
index 000000000..117bd2b53
--- /dev/null
+++ b/man/man2/llistxattr.2
@@ -0,0 +1 @@
+.so man2/listxattr.2
diff --git a/man/man2/llseek.2 b/man/man2/llseek.2
new file mode 100644
index 000000000..1a3f365f2
--- /dev/null
+++ b/man/man2/llseek.2
@@ -0,0 +1,92 @@
+.\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
+.\" Written 10 June 1995 by Andries Brouwer <aeb@cwi.nl>
+.\" and Copyright (C) 2007, 2015, 2020, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Thu Oct 31 15:16:23 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\"
+.TH _llseek 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+_llseek \- reposition read/write file offset
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS__llseek, unsigned int " fd ", unsigned long " offset_high ,
+.BI "            unsigned long " offset_low ", loff_t *" result ,
+.BI "            unsigned int " whence );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR _llseek (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+Note: for information about the
+.BR llseek (3)
+library function, see
+.BR lseek64 (3).
+.P
+The
+.BR _llseek ()
+system call repositions the offset of the open file description associated
+with the file descriptor
+.I fd
+to the value
+.IP
+(offset_high << 32) | offset_low
+.P
+This new offset is a byte offset
+relative to the beginning of the file, the current file offset,
+or the end of the file, depending on whether
+.I whence
+is
+.BR SEEK_SET ,
+.BR SEEK_CUR ,
+or
+.BR SEEK_END ,
+respectively.
+.P
+The new file offset is returned in the argument
+.IR result .
+The  type
+.I loff_t
+is a 64-bit signed type.
+.P
+This system call exists on various 32-bit platforms to support
+seeking to large file offsets.
+.SH RETURN VALUE
+Upon successful completion,
+.BR _llseek ()
+returns 0.
+Otherwise, a value of \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not an open file descriptor.
+.TP
+.B EFAULT
+Problem with copying results to user space.
+.TP
+.B EINVAL
+.I whence
+is invalid.
+.SH VERSIONS
+You probably want to use the
+.BR lseek (2)
+wrapper function instead.
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR lseek (2),
+.BR open (2),
+.BR lseek64 (3)
diff --git a/man/man2/lock.2 b/man/man2/lock.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/lock.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/lookup_dcookie.2 b/man/man2/lookup_dcookie.2
new file mode 100644
index 000000000..acc5e43e6
--- /dev/null
+++ b/man/man2/lookup_dcookie.2
@@ -0,0 +1,86 @@
+.\" Copyright (C) 2003 John Levon <levon@movementarian.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 2004-06-17 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH lookup_dcookie 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lookup_dcookie \- return a directory entry's path
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_lookup_dcookie, uint64_t " cookie ", char *" buffer ,
+.BI "            size_t " len );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR lookup_dcookie (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+Look up the full path of the directory entry specified by the value
+.IR cookie .
+The cookie is an opaque identifier uniquely identifying a particular
+directory entry.
+The buffer given is filled in with the full path of the directory entry.
+.P
+For
+.BR lookup_dcookie ()
+to return successfully,
+the kernel must still hold a cookie reference to the directory entry.
+.SH RETURN VALUE
+On success,
+.BR lookup_dcookie ()
+returns the length of the path string copied into the buffer.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+The buffer was not valid.
+.TP
+.B EINVAL
+The kernel has no registered cookie/directory entry mappings at the
+time of lookup, or the cookie does not refer to a valid directory entry.
+.TP
+.B ENAMETOOLONG
+The name could not fit in the buffer.
+.TP
+.B ENOMEM
+The kernel could not allocate memory for the temporary buffer holding
+the path.
+.TP
+.B EPERM
+The process does not have the capability
+.B CAP_SYS_ADMIN
+required to look up cookie values.
+.TP
+.B ERANGE
+The buffer was not large enough to hold the path of the directory entry.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.43.
+.P
+The
+.B ENAMETOOLONG
+error was added in Linux 2.5.70.
+.SH NOTES
+.BR lookup_dcookie ()
+is a special-purpose system call, currently used only by the
+.BR oprofile (1)
+profiler.
+It relies on a kernel driver to register cookies for directory entries.
+.P
+The path returned may be suffixed by the string " (deleted)" if the directory
+entry has been removed.
+.SH SEE ALSO
+.BR oprofile (1)
diff --git a/man/man2/lremovexattr.2 b/man/man2/lremovexattr.2
new file mode 100644
index 000000000..38d01ccde
--- /dev/null
+++ b/man/man2/lremovexattr.2
@@ -0,0 +1 @@
+.so man2/removexattr.2
diff --git a/man/man2/lseek.2 b/man/man2/lseek.2
new file mode 100644
index 000000000..14fc13734
--- /dev/null
+++ b/man/man2/lseek.2
@@ -0,0 +1,252 @@
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" and Copyright (c) 2011, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)lseek.2	6.5 (Berkeley) 3/10/91
+.\"
+.\" Modified 1993-07-23 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-06-10 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 1996-10-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998-01-17 by Michael Haardt
+.\"   <michael@cantor.informatik.rwth-aachen.de>
+.\" Modified 2001-09-24 by Michael Haardt <michael@moria.de>
+.\" Modified 2003-08-21 by Andries Brouwer <aeb@cwi.nl>
+.\" 2011-09-18, mtk, Added SEEK_DATA + SEEK_HOLE
+.\"
+.TH lseek 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lseek \- reposition read/write file offset
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "off_t lseek(int " fd ", off_t " offset ", int " whence );
+.fi
+.SH DESCRIPTION
+.BR lseek ()
+repositions the file offset of the open file description
+associated with the file descriptor
+.I fd
+to the argument
+.I offset
+according to the directive
+.I whence
+as follows:
+.TP
+.B SEEK_SET
+The file offset is set to
+.I offset
+bytes.
+.TP
+.B SEEK_CUR
+The file offset is set to its current location plus
+.I offset
+bytes.
+.TP
+.B SEEK_END
+The file offset is set to the size of the file plus
+.I offset
+bytes.
+.P
+.BR lseek ()
+allows the file offset to be set beyond the end
+of the file (but this does not change the size of the file).
+If data is later written at this point, subsequent reads of the data
+in the gap (a "hole") return null bytes (\[aq]\e0\[aq]) until
+data is actually written into the gap.
+.SS Seeking file data and holes
+Since Linux 3.1, Linux supports the following additional values for
+.IR whence :
+.TP
+.B SEEK_DATA
+Adjust the file offset to the next location
+in the file greater than or equal to
+.I offset
+containing data.
+If
+.I offset
+points to data,
+then the file offset is set to
+.IR offset .
+.TP
+.B SEEK_HOLE
+Adjust the file offset to the next hole in the file
+greater than or equal to
+.IR offset .
+If
+.I offset
+points into the middle of a hole,
+then the file offset is set to
+.IR offset .
+If there is no hole past
+.IR offset ,
+then the file offset is adjusted to the end of the file
+(i.e., there is an implicit hole at the end of any file).
+.P
+In both of the above cases,
+.BR lseek ()
+fails if
+.I offset
+points past the end of the file.
+.P
+These operations allow applications to map holes in a sparsely
+allocated file.
+This can be useful for applications such as file backup tools,
+which can save space when creating backups and preserve holes,
+if they have a mechanism for discovering holes.
+.P
+For the purposes of these operations, a hole is a sequence of zeros that
+(normally) has not been allocated in the underlying file storage.
+However, a filesystem is not obliged to report holes,
+so these operations are not a guaranteed mechanism for
+mapping the storage space actually allocated to a file.
+(Furthermore, a sequence of zeros that actually has been written
+to the underlying storage may not be reported as a hole.)
+In the simplest implementation,
+a filesystem can support the operations by making
+.B SEEK_HOLE
+always return the offset of the end of the file,
+and making
+.B SEEK_DATA
+always return
+.I offset
+(i.e., even if the location referred to by
+.I offset
+is a hole,
+it can be considered to consist of data that is a sequence of zeros).
+.\" https://lkml.org/lkml/2011/4/22/79
+.\" http://lwn.net/Articles/440255/
+.\" http://blogs.oracle.com/bonwick/entry/seek_hole_and_seek_data
+.P
+The
+.B _GNU_SOURCE
+feature test macro must be defined in order to obtain the definitions of
+.B SEEK_DATA
+and
+.B SEEK_HOLE
+from
+.IR <unistd.h> .
+.P
+The
+.B SEEK_HOLE
+and
+.B SEEK_DATA
+operations are supported for the following filesystems:
+.IP \[bu] 3
+Btrfs (since Linux 3.1)
+.IP \[bu]
+OCFS (since Linux 3.2)
+.\" commit 93862d5e1ab875664c6cc95254fc365028a48bb1
+.IP \[bu]
+XFS (since Linux 3.5)
+.IP \[bu]
+ext4 (since Linux 3.8)
+.IP \[bu]
+.BR tmpfs (5)
+(since Linux 3.8)
+.IP \[bu]
+NFS (since Linux 3.18)
+.\" commit 1c6dcbe5ceff81c2cf8d929646af675cd59fe7c0
+.\" commit 24bab491220faa446d945624086d838af41d616c
+.IP \[bu]
+FUSE (since Linux 4.5)
+.\" commit 0b5da8db145bfd44266ac964a2636a0cf8d7c286
+.IP \[bu]
+GFS2 (since Linux 4.15)
+.\" commit 3a27411cb4bc3ce31db228e3569ad01b462a4310
+.SH RETURN VALUE
+Upon successful completion,
+.BR lseek ()
+returns the resulting offset location as measured in bytes from the
+beginning of the file.
+On error, the value \fI(off_t)\ \-1\fP is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not an open file descriptor.
+.TP
+.B EINVAL
+.I whence
+is not valid.
+Or: the resulting file offset would be negative,
+or beyond the end of a seekable device.
+.\" Some systems may allow negative offsets for character devices
+.\" and/or for remote filesystems.
+.TP
+.B ENXIO
+.I whence
+is
+.B SEEK_DATA
+or
+.BR SEEK_HOLE ,
+and
+.I offset
+is beyond the end of the file, or
+.I whence
+is
+.B SEEK_DATA
+and
+.I offset
+is within a hole at the end of the file.
+.TP
+.B EOVERFLOW
+.\" HP-UX 11 says EINVAL for this case (but POSIX.1 says EOVERFLOW)
+The resulting file offset cannot be represented in an
+.IR off_t .
+.TP
+.B ESPIPE
+.I fd
+is associated with a pipe, socket, or FIFO.
+.SH VERSIONS
+On Linux, using
+.BR lseek ()
+on a terminal device fails with the error
+.BR ESPIPE .
+.\" Other systems return the number of written characters,
+.\" using SEEK_SET to set the counter. (Of written characters.)
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.P
+.B SEEK_DATA
+and
+.B SEEK_HOLE
+are nonstandard extensions also present in Solaris,
+FreeBSD, and DragonFly BSD;
+they are proposed for inclusion in the next POSIX revision (Issue 8).
+.\" FIXME . Review http://austingroupbugs.net/view.php?id=415 in the future
+.SH NOTES
+See
+.BR open (2)
+for a discussion of the relationship between file descriptors,
+open file descriptions, and files.
+.P
+If the
+.B O_APPEND
+file status flag is set on the open file description,
+then a
+.BR write (2)
+.I always
+moves the file offset to the end of the file, regardless of the use of
+.BR lseek ().
+.P
+Some devices are incapable of seeking and POSIX does not specify which
+devices must support
+.BR lseek ().
+.SH SEE ALSO
+.BR dup (2),
+.BR fallocate (2),
+.BR fork (2),
+.BR open (2),
+.BR fseek (3),
+.BR lseek64 (3),
+.BR posix_fallocate (3)
diff --git a/man/man2/lsetxattr.2 b/man/man2/lsetxattr.2
new file mode 100644
index 000000000..dc0780751
--- /dev/null
+++ b/man/man2/lsetxattr.2
@@ -0,0 +1 @@
+.so man2/setxattr.2
diff --git a/man/man2/lstat.2 b/man/man2/lstat.2
new file mode 100644
index 000000000..b1a86c195
--- /dev/null
+++ b/man/man2/lstat.2
@@ -0,0 +1 @@
+.so man2/stat.2
diff --git a/man/man2/lstat64.2 b/man/man2/lstat64.2
new file mode 100644
index 000000000..89b1c84d9
--- /dev/null
+++ b/man/man2/lstat64.2
@@ -0,0 +1 @@
+.so man2/lstat.2
diff --git a/man/man2/madvise.2 b/man/man2/madvise.2
new file mode 100644
index 000000000..441edfbc1
--- /dev/null
+++ b/man/man2/madvise.2
@@ -0,0 +1,898 @@
+.\" Copyright (C) 2001 David Gómez <davidge@jazzfree.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Based on comments from mm/filemap.c. Last modified on 10-06-2001
+.\" Modified, 25 Feb 2002, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"	Added notes on MADV_DONTNEED
+.\" 2010-06-19, mtk, Added documentation of MADV_MERGEABLE and
+.\"     MADV_UNMERGEABLE
+.\" 2010-06-15, Andi Kleen, Add documentation of MADV_HWPOISON.
+.\" 2010-06-19, Andi Kleen, Add documentation of MADV_SOFT_OFFLINE.
+.\" 2011-09-18, Doug Goldstein <cardoe@cardoe.com>
+.\"     Document MADV_HUGEPAGE and MADV_NOHUGEPAGE
+.\"
+.TH madvise 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+madvise \- give advice about use of memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "int madvise(void " addr [. length "], size_t " length ", int " advice );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR madvise ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    Up to and including glibc 2.19:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR madvise ()
+system call is used to give advice or directions to the kernel
+about the address range beginning at address
+.I addr
+and with size
+.IR length .
+.BR madvise ()
+only operates on whole pages, therefore
+.I addr
+must be page-aligned.
+The value of
+.I length
+is rounded up to a multiple of page size.
+In most cases,
+the goal of such advice is to improve system or application performance.
+.P
+Initially, the system call supported a set of "conventional"
+.I advice
+values, which are also available on several other implementations.
+(Note, though, that
+.BR madvise ()
+is not specified in POSIX.)
+Subsequently, a number of Linux-specific
+.I advice
+values have been added.
+.\"
+.\" ======================================================================
+.\"
+.SS Conventional advice values
+The
+.I advice
+values listed below
+allow an application to tell the kernel how it expects to use
+some mapped or shared memory areas, so that the kernel can choose
+appropriate read-ahead and caching techniques.
+These
+.I advice
+values do not influence the semantics of the application
+(except in the case of
+.BR MADV_DONTNEED ),
+but may influence its performance.
+All of the
+.I advice
+values listed here have analogs in the POSIX-specified
+.BR posix_madvise (3)
+function, and the values have the same meanings, with the exception of
+.BR MADV_DONTNEED .
+.P
+The advice is indicated in the
+.I advice
+argument, which is one of the following:
+.TP
+.B MADV_NORMAL
+No special treatment.
+This is the default.
+.TP
+.B MADV_RANDOM
+Expect page references in random order.
+(Hence, read ahead may be less useful than normally.)
+.TP
+.B MADV_SEQUENTIAL
+Expect page references in sequential order.
+(Hence, pages in the given range can be aggressively read ahead,
+and may be freed soon after they are accessed.)
+.TP
+.B MADV_WILLNEED
+Expect access in the near future.
+(Hence, it might be a good idea to read some pages ahead.)
+.TP
+.B MADV_DONTNEED
+Do not expect access in the near future.
+(For the time being, the application is finished with the given range,
+so the kernel can free resources associated with it.)
+.IP
+After a successful
+.B MADV_DONTNEED
+operation,
+the semantics of memory access in the specified region are changed:
+subsequent accesses of pages in the range will succeed, but will result
+in either repopulating the memory contents from the
+up-to-date contents of the underlying mapped file
+(for shared file mappings, shared anonymous mappings,
+and shmem-based techniques such as System V shared memory segments)
+or zero-fill-on-demand pages for anonymous private mappings.
+.IP
+Note that, when applied to shared mappings,
+.B MADV_DONTNEED
+might not lead to immediate freeing of the pages in the range.
+The kernel is free to delay freeing the pages until an appropriate moment.
+The resident set size (RSS) of the calling process will be immediately
+reduced however.
+.IP
+.B MADV_DONTNEED
+cannot be applied to locked pages, or
+.B VM_PFNMAP
+pages.
+(Pages marked with the kernel-internal
+.B VM_PFNMAP
+.\" http://lwn.net/Articles/162860/
+flag are special memory areas that are not managed
+by the virtual memory subsystem.
+Such pages are typically created by device drivers that
+map the pages into user space.)
+.IP
+Support for Huge TLB pages was added in Linux v5.18.
+Addresses within a mapping backed by Huge TLB pages must be aligned
+to the underlying Huge TLB page size,
+and the range length is rounded up
+to a multiple of the underlying Huge TLB page size.
+.\"
+.\" ======================================================================
+.\"
+.SS Linux-specific advice values
+The following Linux-specific
+.I advice
+values have no counterparts in the POSIX-specified
+.BR posix_madvise (3),
+and may or may not have counterparts in the
+.BR madvise ()
+interface available on other implementations.
+Note that some of these operations change the semantics of memory accesses.
+.TP
+.BR MADV_REMOVE " (since Linux 2.6.16)"
+.\" commit f6b3ec238d12c8cc6cc71490c6e3127988460349
+Free up a given range of pages
+and its associated backing store.
+This is equivalent to punching a hole in the corresponding
+range of the backing store (see
+.BR fallocate (2)).
+Subsequent accesses in the specified address range will see
+data with a value of zero.
+.\" Databases want to use this feature to drop a section of their
+.\" bufferpool (shared memory segments) - without writing back to
+.\" disk/swap space.  This feature is also useful for supporting
+.\" hot-plug memory on UML.
+.IP
+The specified address range must be mapped shared and writable.
+This flag cannot be applied to locked pages, or
+.B VM_PFNMAP
+pages.
+.IP
+In the initial implementation, only
+.BR tmpfs (5)
+supported
+.BR MADV_REMOVE ;
+but since Linux 3.5,
+.\" commit 3f31d07571eeea18a7d34db9af21d2285b807a17
+any filesystem which supports the
+.BR fallocate (2)
+.B FALLOC_FL_PUNCH_HOLE
+mode also supports
+.BR MADV_REMOVE .
+Filesystems which do not support
+.B MADV_REMOVE
+fail with the error
+.BR EOPNOTSUPP .
+.IP
+Support for the Huge TLB filesystem was added in Linux v4.3.
+.TP
+.BR MADV_DONTFORK " (since Linux 2.6.16)"
+.\" commit f822566165dd46ff5de9bf895cfa6c51f53bb0c4
+.\" See http://lwn.net/Articles/171941/
+Do not make the pages in this range available to the child after a
+.BR fork (2).
+This is useful to prevent copy-on-write semantics from changing
+the physical location of a page if the parent writes to it after a
+.BR fork (2).
+(Such page relocations cause problems for hardware that
+DMAs into the page.)
+.\" [PATCH] madvise MADV_DONTFORK/MADV_DOFORK
+.\" Currently, copy-on-write may change the physical address of
+.\" a page even if the user requested that the page is pinned in
+.\" memory (either by mlock or by get_user_pages).  This happens
+.\" if the process forks meanwhile, and the parent writes to that
+.\" page.  As a result, the page is orphaned: in case of
+.\" get_user_pages, the application will never see any data hardware
+.\" DMA's into this page after the COW.  In case of mlock'd memory,
+.\" the parent is not getting the realtime/security benefits of mlock.
+.\"
+.\" In particular, this affects the Infiniband modules which do DMA from
+.\" and into user pages all the time.
+.\"
+.\" This patch adds madvise options to control whether memory range is
+.\" inherited across fork. Useful e.g. for when hardware is doing DMA
+.\" from/into these pages.  Could also be useful to an application
+.\" wanting to speed up its forks by cutting large areas out of
+.\" consideration.
+.\"
+.\" SEE ALSO: http://lwn.net/Articles/171941/
+.\" "Tweaks to madvise() and posix_fadvise()", 14 Feb 2006
+.TP
+.BR MADV_DOFORK " (since Linux 2.6.16)"
+Undo the effect of
+.BR MADV_DONTFORK ,
+restoring the default behavior, whereby a mapping is inherited across
+.BR fork (2).
+.TP
+.BR MADV_HWPOISON " (since Linux 2.6.32)"
+.\" commit 9893e49d64a4874ea67849ee2cfbf3f3d6817573
+Poison the pages in the range specified by
+.I addr
+and
+.I length
+and handle subsequent references to those pages
+like a hardware memory corruption.
+This operation is available only for privileged
+.RB ( CAP_SYS_ADMIN )
+processes.
+This operation may result in the calling process receiving a
+.B SIGBUS
+and the page being unmapped.
+.IP
+This feature is intended for testing of memory error-handling code;
+it is available only if the kernel was configured with
+.BR CONFIG_MEMORY_FAILURE .
+.TP
+.BR MADV_MERGEABLE " (since Linux 2.6.32)"
+.\" commit f8af4da3b4c14e7267c4ffb952079af3912c51c5
+Enable Kernel Samepage Merging (KSM) for the pages in the range specified by
+.I addr
+and
+.IR length .
+The kernel regularly scans those areas of user memory that have
+been marked as mergeable,
+looking for pages with identical content.
+These are replaced by a single write-protected page (which is automatically
+copied if a process later wants to update the content of the page).
+KSM merges only private anonymous pages (see
+.BR mmap (2)).
+.IP
+The KSM feature is intended for applications that generate many
+instances of the same data (e.g., virtualization systems such as KVM).
+It can consume a lot of processing power; use with care.
+See the Linux kernel source file
+.I Documentation/admin\-guide/mm/ksm.rst
+for more details.
+.IP
+The
+.B MADV_MERGEABLE
+and
+.B MADV_UNMERGEABLE
+operations are available only if the kernel was configured with
+.BR CONFIG_KSM .
+.TP
+.BR MADV_UNMERGEABLE " (since Linux 2.6.32)"
+Undo the effect of an earlier
+.B MADV_MERGEABLE
+operation on the specified address range;
+KSM unmerges whatever pages it had merged in the address range specified by
+.I addr
+and
+.IR length .
+.TP
+.BR MADV_SOFT_OFFLINE " (since Linux 2.6.33)"
+.\" commit afcf938ee0aac4ef95b1a23bac704c6fbeb26de6
+Soft offline the pages in the range specified by
+.I addr
+and
+.IR length .
+The memory of each page in the specified range is preserved
+(i.e., when next accessed, the same content will be visible,
+but in a new physical page frame),
+and the original page is offlined
+(i.e., no longer used, and taken out of normal memory management).
+The effect of the
+.B MADV_SOFT_OFFLINE
+operation is invisible to (i.e., does not change the semantics of)
+the calling process.
+.IP
+This feature is intended for testing of memory error-handling code;
+it is available only if the kernel was configured with
+.BR CONFIG_MEMORY_FAILURE .
+.TP
+.BR MADV_HUGEPAGE " (since Linux 2.6.38)"
+.\" commit 0af4e98b6b095c74588af04872f83d333c958c32
+.\" http://lwn.net/Articles/358904/
+.\" https://lwn.net/Articles/423584/
+Enable Transparent Huge Pages (THP) for pages in the range specified by
+.I addr
+and
+.IR length .
+The kernel will regularly scan the areas marked as huge page candidates
+to replace them with huge pages.
+The kernel will also allocate huge pages directly when the region is
+naturally aligned to the huge page size (see
+.BR posix_memalign (2)).
+.IP
+This feature is primarily aimed at applications that use large mappings of
+data and access large regions of that memory at a time (e.g., virtualization
+systems such as QEMU).
+It can very easily waste memory (e.g., a 2\ MB mapping that only ever accesses
+1 byte will result in 2\ MB of wired memory instead of one 4\ KB page).
+See the Linux kernel source file
+.I Documentation/admin\-guide/mm/transhuge.rst
+for more details.
+.IP
+Most common kernels configurations provide
+.BR MADV_HUGEPAGE -style
+behavior by default, and thus
+.B MADV_HUGEPAGE
+is normally not necessary.
+It is mostly intended for embedded systems, where
+.BR MADV_HUGEPAGE -style
+behavior may not be enabled by default in the kernel.
+On such systems,
+this flag can be used in order to selectively enable THP.
+Whenever
+.B MADV_HUGEPAGE
+is used, it should always be in regions of memory with
+an access pattern that the developer knows in advance won't risk
+to increase the memory footprint of the application when transparent
+hugepages are enabled.
+.IP
+.\" commit 99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0
+Since Linux 5.4,
+automatic scan of eligible areas and replacement by huge pages works with
+private anonymous pages (see
+.BR mmap (2)),
+shmem pages,
+and file-backed pages.
+For all memory types,
+memory may only be replaced by huge pages on hugepage-aligned boundaries.
+For file-mapped memory
+\[em]including tmpfs (see
+.BR tmpfs (2))\[em]
+the mapping must also be naturally hugepage-aligned within the file.
+Additionally,
+for file-backed,
+non-tmpfs memory,
+the file must not be open for write and the mapping must be executable.
+.IP
+The VMA must not be marked
+.BR VM_NOHUGEPAGE ,
+.BR VM_HUGETLB ,
+.BR VM_IO ,
+.BR VM_DONTEXPAND ,
+.BR VM_MIXEDMAP ,
+or
+.BR VM_PFNMAP ,
+nor can it be stack memory or backed by a DAX-enabled device
+(unless the DAX device is hot-plugged as System RAM).
+The process must also not have
+.B PR_SET_THP_DISABLE
+set (see
+.BR prctl (2)).
+.IP
+The
+.BR MADV_HUGEPAGE ,
+.BR MADV_NOHUGEPAGE ,
+and
+.B MADV_COLLAPSE
+operations are available only if the kernel was configured with
+.B CONFIG_TRANSPARENT_HUGEPAGE
+and file/shmem memory is only supported if the kernel was configured with
+.BR CONFIG_READ_ONLY_THP_FOR_FS .
+.TP
+.BR MADV_NOHUGEPAGE " (since Linux 2.6.38)"
+Ensures that memory in the address range specified by
+.I addr
+and
+.I length
+will not be backed by transparent hugepages.
+.TP
+.BR MADV_COLLAPSE " (since Linux 6.1)"
+.\" commit 7d8faaf155454f8798ec56404faca29a82689c77
+.\" commit 34488399fa08faaf664743fa54b271eb6f9e1321
+Perform a best-effort synchronous collapse of
+the native pages mapped by the memory range
+into Transparent Huge Pages (THPs).
+.B MADV_COLLAPSE
+operates on the current state of memory of the calling process and
+makes no persistent changes or guarantees on how pages will be mapped,
+constructed,
+or faulted in the future.
+.IP
+.B MADV_COLLAPSE
+supports private anonymous pages (see
+.BR mmap (2)),
+shmem pages,
+and file-backed pages.
+See
+.B MADV_HUGEPAGE
+for general information on memory requirements for THP.
+If the range provided spans multiple VMAs,
+the semantics of the collapse over each VMA is independent from the others.
+If collapse of a given huge page-aligned/sized region fails,
+the operation may continue to attempt collapsing
+the remainder of the specified memory.
+.B MADV_COLLAPSE
+will automatically clamp the provided range to be hugepage-aligned.
+.IP
+All non-resident pages covered by the range
+will first be swapped/faulted-in,
+before being copied onto a freshly allocated hugepage.
+If the native pages compose the same PTE-mapped hugepage,
+and are suitably aligned,
+allocation of a new hugepage may be elided and
+collapse may happen in-place.
+Unmapped pages will have their data directly initialized to 0
+in the new hugepage.
+However,
+for every eligible hugepage-aligned/sized region to be collapsed,
+at least one page must currently be backed by physical memory.
+.IP
+.B MADV_COLLAPSE
+is independent of any sysfs
+(see
+.BR sysfs (5))
+setting under
+.IR /sys/kernel/mm/transparent_hugepage ,
+both in terms of determining THP eligibility,
+and allocation semantics.
+See Linux kernel source file
+.I Documentation/admin\-guide/mm/transhuge.rst
+for more information.
+.B MADV_COLLAPSE
+also ignores
+.B huge=
+tmpfs mount when operating on tmpfs files.
+Allocation for the new hugepage may enter direct reclaim and/or compaction,
+regardless of VMA flags
+(though
+.B VM_NOHUGEPAGE
+is still respected).
+.IP
+When the system has multiple NUMA nodes,
+the hugepage will be allocated from
+the node providing the most native pages.
+.IP
+If all hugepage-sized/aligned regions covered by the provided range were
+either successfully collapsed,
+or were already PMD-mapped THPs,
+this operation will be deemed successful.
+Note that this doesn't guarantee anything about
+other possible mappings of the memory.
+In the event multiple hugepage-aligned/sized areas fail to collapse,
+only the most-recently\[en]failed code will be set in
+.IR errno .
+.TP
+.BR MADV_DONTDUMP " (since Linux 3.4)"
+.\" commit 909af768e88867016f427264ae39d27a57b6a8ed
+.\" commit accb61fe7bb0f5c2a4102239e4981650f9048519
+Exclude from a core dump those pages in the range specified by
+.I addr
+and
+.IR length .
+This is useful in applications that have large areas of memory
+that are known not to be useful in a core dump.
+The effect of
+.B MADV_DONTDUMP
+takes precedence over the bit mask that is set via the
+.IR /proc/ pid /coredump_filter
+file (see
+.BR core (5)).
+.TP
+.BR MADV_DODUMP " (since Linux 3.4)"
+Undo the effect of an earlier
+.BR MADV_DONTDUMP .
+.TP
+.BR MADV_FREE " (since Linux 4.5)"
+The application no longer requires the pages in the range specified by
+.I addr
+and
+.IR len .
+The kernel can thus free these pages,
+but the freeing could be delayed until memory pressure occurs.
+For each of the pages that has been marked to be freed
+but has not yet been freed,
+the free operation will be canceled if the caller writes into the page.
+After a successful
+.B MADV_FREE
+operation, any stale data (i.e., dirty, unwritten pages) will be lost
+when the kernel frees the pages.
+However, subsequent writes to pages in the range will succeed
+and then kernel cannot free those dirtied pages,
+so that the caller can always see just written data.
+If there is no subsequent write,
+the kernel can free the pages at any time.
+Once pages in the range have been freed, the caller will
+see zero-fill-on-demand pages upon subsequent page references.
+.IP
+The
+.B MADV_FREE
+operation
+can be applied only to private anonymous pages (see
+.BR mmap (2)).
+Before Linux 4.12,
+.\" commit 93e06c7a645343d222c9a838834a51042eebbbf7
+when freeing pages on a swapless system,
+the pages in the given range are freed instantly,
+regardless of memory pressure.
+.TP
+.BR MADV_WIPEONFORK " (since Linux 4.14)"
+.\" commit d2cd9ede6e193dd7d88b6d27399e96229a551b19
+Present the child process with zero-filled memory in this range after a
+.BR fork (2).
+This is useful in forking servers in order to ensure
+that sensitive per-process data
+(for example, PRNG seeds, cryptographic secrets, and so on)
+is not handed to child processes.
+.IP
+The
+.B MADV_WIPEONFORK
+operation can be applied only to private anonymous pages (see
+.BR mmap (2)).
+.IP
+Within the child created by
+.BR fork (2),
+the
+.B MADV_WIPEONFORK
+setting remains in place on the specified address range.
+This setting is cleared during
+.BR execve (2).
+.TP
+.BR MADV_KEEPONFORK " (since Linux 4.14)"
+.\" commit d2cd9ede6e193dd7d88b6d27399e96229a551b19
+Undo the effect of an earlier
+.BR MADV_WIPEONFORK .
+.TP
+.BR MADV_COLD " (since Linux 5.4)"
+.\" commit 9c276cc65a58faf98be8e56962745ec99ab87636
+Deactivate a given range of pages.
+This will make the pages a more probable
+reclaim target should there be a memory pressure.
+This is a nondestructive operation.
+The advice might be ignored for some pages in the range when it is not
+applicable.
+.TP
+.BR MADV_PAGEOUT " (since Linux 5.4)"
+.\" commit 1a4e58cce84ee88129d5d49c064bd2852b481357
+Reclaim a given range of pages.
+This is done to free up memory occupied by these pages.
+If a page is anonymous, it will be swapped out.
+If a page is file-backed and dirty, it will be written back to the backing
+storage.
+The advice might be ignored for some pages in the range when it is not
+applicable.
+.TP
+.BR MADV_POPULATE_READ " (since Linux 5.14)"
+"Populate (prefault) page tables readable,
+faulting in all pages in the range just as if manually reading from each page;
+however,
+avoid the actual memory access that would have been performed after handling
+the fault.
+.IP
+In contrast to
+.BR MAP_POPULATE ,
+.B MADV_POPULATE_READ
+does not hide errors,
+can be applied to (parts of) existing mappings and will always populate
+(prefault) page tables readable.
+One example use case is prefaulting a file mapping,
+reading all file content from disk;
+however,
+pages won't be dirtied and consequently won't have to be written back to disk
+when evicting the pages from memory.
+.IP
+Depending on the underlying mapping,
+map the shared zeropage,
+preallocate memory or read the underlying file;
+files with holes might or might not preallocate blocks.
+If populating fails,
+a
+.B SIGBUS
+signal is not generated; instead, an error is returned.
+.IP
+If
+.B MADV_POPULATE_READ
+succeeds,
+all page tables have been populated (prefaulted) readable once.
+If
+.B MADV_POPULATE_READ
+fails,
+some page tables might have been populated.
+.IP
+.B MADV_POPULATE_READ
+cannot be applied to mappings without read permissions
+and special mappings,
+for example,
+mappings marked with kernel-internal flags such as
+.B VM_PFNMAP
+or
+.BR VM_IO ,
+or secret memory regions created using
+.BR memfd_secret(2) .
+.IP
+Note that with
+.BR MADV_POPULATE_READ ,
+the process can be killed at any moment when the system runs out of memory.
+.TP
+.BR MADV_POPULATE_WRITE " (since Linux 5.14)"
+Populate (prefault) page tables writable,
+faulting in all pages in the range just as if manually writing to each
+each page;
+however,
+avoid the actual memory access that would have been performed after handling
+the fault.
+.IP
+In contrast to
+.BR MAP_POPULATE ,
+MADV_POPULATE_WRITE does not hide errors,
+can be applied to (parts of) existing mappings and will always populate
+(prefault) page tables writable.
+One example use case is preallocating memory,
+breaking any CoW (Copy on Write).
+.IP
+Depending on the underlying mapping,
+preallocate memory or read the underlying file;
+files with holes will preallocate blocks.
+If populating fails,
+a
+.B SIGBUS
+signal is not generated; instead, an error is returned.
+.IP
+If
+.B MADV_POPULATE_WRITE
+succeeds,
+all page tables have been populated (prefaulted) writable once.
+If
+.B MADV_POPULATE_WRITE
+fails,
+some page tables might have been populated.
+.IP
+.B MADV_POPULATE_WRITE
+cannot be applied to mappings without write permissions
+and special mappings,
+for example,
+mappings marked with kernel-internal flags such as
+.B VM_PFNMAP
+or
+.BR VM_IO ,
+or secret memory regions created using
+.BR memfd_secret(2) .
+.IP
+Note that with
+.BR MADV_POPULATE_WRITE ,
+the process can be killed at any moment when the system runs out of memory.
+.SH RETURN VALUE
+On success,
+.BR madvise ()
+returns zero.
+On error, it returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.I advice
+is
+.BR MADV_REMOVE ,
+but the specified address range is not a shared writable mapping.
+.TP
+.B EAGAIN
+A kernel resource was temporarily unavailable.
+.TP
+.B EBADF
+The map exists, but the area maps something that isn't a file.
+.TP
+.B EBUSY
+(for
+.BR MADV_COLLAPSE )
+Could not charge hugepage to cgroup: cgroup limit exceeded.
+.TP
+.B EFAULT
+.I advice
+is
+.B MADV_POPULATE_READ
+or
+.BR MADV_POPULATE_WRITE ,
+and populating (prefaulting) page tables failed because a
+.B SIGBUS
+would have been generated on actual memory access and the reason is not a
+HW poisoned page
+(HW poisoned pages can,
+for example,
+be created using the
+.B MADV_HWPOISON
+flag described elsewhere in this page).
+.TP
+.B EINVAL
+.I addr
+is not page-aligned or
+.I length
+is negative.
+.\" .I length
+.\" is zero,
+.TP
+.B EINVAL
+.I advice
+is not a valid.
+.TP
+.B EINVAL
+.I advice
+is
+.B MADV_COLD
+or
+.B MADV_PAGEOUT
+and the specified address range includes locked, Huge TLB pages, or
+.B VM_PFNMAP
+pages.
+.TP
+.B EINVAL
+.I advice
+is
+.B MADV_DONTNEED
+or
+.B MADV_REMOVE
+and the specified address range includes locked, Huge TLB pages, or
+.B VM_PFNMAP
+pages.
+.TP
+.B EINVAL
+.I advice
+is
+.B MADV_MERGEABLE
+or
+.BR MADV_UNMERGEABLE ,
+but the kernel was not configured with
+.BR CONFIG_KSM .
+.TP
+.B EINVAL
+.I advice
+is
+.B MADV_FREE
+or
+.B MADV_WIPEONFORK
+but the specified address range includes file, Huge TLB,
+.BR MAP_SHARED ,
+or
+.B VM_PFNMAP
+ranges.
+.TP
+.B EINVAL
+.I advice
+is
+.B MADV_POPULATE_READ
+or
+.BR MADV_POPULATE_WRITE ,
+but the specified address range includes ranges with insufficient permissions
+or special mappings,
+for example,
+mappings marked with kernel-internal flags such a
+.B VM_IO
+or
+.BR VM_PFNMAP ,
+or secret memory regions created using
+.BR memfd_secret(2) .
+.TP
+.B EIO
+(for
+.BR MADV_WILLNEED )
+Paging in this area would exceed the process's
+maximum resident set size.
+.TP
+.B ENOMEM
+(for
+.BR MADV_WILLNEED )
+Not enough memory: paging in failed.
+.TP
+.B ENOMEM
+(for
+.BR MADV_COLLAPSE )
+Not enough memory: could not allocate hugepage.
+.TP
+.B ENOMEM
+Addresses in the specified range are not currently
+mapped, or are outside the address space of the process.
+.TP
+.B ENOMEM
+.I advice
+is
+.B MADV_POPULATE_READ
+or
+.BR MADV_POPULATE_WRITE ,
+and populating (prefaulting) page tables failed because there was not enough
+memory.
+.TP
+.B EPERM
+.I advice
+is
+.BR MADV_HWPOISON ,
+but the caller does not have the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B EHWPOISON
+.I advice
+is
+.B MADV_POPULATE_READ
+or
+.BR MADV_POPULATE_WRITE ,
+and populating (prefaulting) page tables failed because a HW poisoned page
+(HW poisoned pages can,
+for example,
+be created using the
+.B MADV_HWPOISON
+flag described elsewhere in this page)
+was encountered.
+.SH VERSIONS
+Versions of this system call, implementing a wide variety of
+.I advice
+values, exist on many other implementations.
+Other implementations typically implement at least the flags listed
+above under
+.IR "Conventional advice flags" ,
+albeit with some variation in semantics.
+.P
+POSIX.1-2001 describes
+.BR posix_madvise (3)
+with constants
+.BR POSIX_MADV_NORMAL ,
+.BR POSIX_MADV_RANDOM ,
+.BR POSIX_MADV_SEQUENTIAL ,
+.BR POSIX_MADV_WILLNEED ,
+and
+.BR POSIX_MADV_DONTNEED ,
+and so on, with behavior close to the similarly named flags listed above.
+.SS Linux
+The Linux implementation requires that the address
+.I addr
+be page-aligned, and allows
+.I length
+to be zero.
+If there are some parts of the specified address range
+that are not mapped, the Linux version of
+.BR madvise ()
+ignores them and applies the call to the rest (but returns
+.B ENOMEM
+from the system call, as it should).
+.P
+.I madvise(0,\ 0,\ advice)
+will return zero iff
+.I advice
+is supported by the kernel and can be relied on to probe for support.
+.SH STANDARDS
+None.
+.SH HISTORY
+First appeared in 4.4BSD.
+.P
+Since Linux 3.18,
+.\" commit d3ac21cacc24790eb45d735769f35753f5b56ceb
+support for this system call is optional,
+depending on the setting of the
+.B CONFIG_ADVISE_SYSCALLS
+configuration option.
+.SH SEE ALSO
+.BR getrlimit (2),
+.BR memfd_secret (2),
+.BR mincore (2),
+.BR mmap (2),
+.BR mprotect (2),
+.BR msync (2),
+.BR munmap (2),
+.BR prctl (2),
+.BR process_madvise (2),
+.BR posix_madvise (3),
+.BR core (5)
diff --git a/man/man2/madvise1.2 b/man/man2/madvise1.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/madvise1.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/mbind.2 b/man/man2/mbind.2
new file mode 100644
index 000000000..96264ce81
--- /dev/null
+++ b/man/man2/mbind.2
@@ -0,0 +1,521 @@
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft-var
+.\"
+.\" Copyright 2003,2004 Andi Kleen, SuSE Labs.
+.\" and Copyright 2007 Lee Schermerhorn, Hewlett Packard
+.\"
+.\" 2006-02-03, mtk, substantial wording changes and other improvements
+.\" 2007-08-27, Lee Schermerhorn <Lee.Schermerhorn@hp.com>
+.\"	more precise specification of behavior.
+.\"
+.\" FIXME
+.\" Linux 3.8 added MPOL_MF_LAZY, which needs to be documented.
+.\" Does it also apply for move_pages()?
+.\"
+.\"                commit b24f53a0bea38b266d219ee651b22dba727c44ae
+.\"                Author: Lee Schermerhorn <lee.schermerhorn@hp.com>
+.\"                Date:   Thu Oct 25 14:16:32 2012 +0200
+.\"
+.TH mbind 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbind \- set memory policy for a memory range
+.SH LIBRARY
+NUMA (Non-Uniform Memory Access) policy library
+.RI ( libnuma ", " \-lnuma )
+.SH SYNOPSIS
+.nf
+.B "#include <numaif.h>"
+.P
+.BI "long mbind(void " addr [. len "], unsigned long " len  ", int " mode ,
+.BI "           const unsigned long " nodemask [(. maxnode " + ULONG_WIDTH - 1)"
+.B "                                        / ULONG_WIDTH],"
+.BI "           unsigned long " maxnode ", unsigned int " flags );
+.fi
+.SH DESCRIPTION
+.BR mbind ()
+sets the NUMA memory policy,
+which consists of a policy mode and zero or more nodes,
+for the memory range starting with
+.I addr
+and continuing for
+.I len
+bytes.
+The memory policy defines from which node memory is allocated.
+.P
+If the memory range specified by the
+.IR addr " and " len
+arguments includes an "anonymous" region of memory\[em]that is
+a region of memory created using the
+.BR mmap (2)
+system call with the
+.BR MAP_ANONYMOUS \[em]or
+a memory-mapped file, mapped using the
+.BR mmap (2)
+system call with the
+.B MAP_PRIVATE
+flag, pages will be allocated only according to the specified
+policy when the application writes (stores) to the page.
+For anonymous regions, an initial read access will use a shared
+page in the kernel containing all zeros.
+For a file mapped with
+.BR MAP_PRIVATE ,
+an initial read access will allocate pages according to the
+memory policy of the thread that causes the page to be allocated.
+This may not be the thread that called
+.BR mbind ().
+.P
+The specified policy will be ignored for any
+.B MAP_SHARED
+mappings in the specified memory range.
+Rather the pages will be allocated according to the memory policy
+of the thread that caused the page to be allocated.
+Again, this may not be the thread that called
+.BR mbind ().
+.P
+If the specified memory range includes a shared memory region
+created using the
+.BR shmget (2)
+system call and attached using the
+.BR shmat (2)
+system call,
+pages allocated for the anonymous or shared memory region will
+be allocated according to the policy specified, regardless of which
+process attached to the shared memory segment causes the allocation.
+If, however, the shared memory region was created with the
+.B SHM_HUGETLB
+flag,
+the huge pages will be allocated according to the policy specified
+only if the page allocation is caused by the process that calls
+.BR mbind ()
+for that region.
+.P
+By default,
+.BR mbind ()
+has an effect only for new allocations; if the pages inside
+the range have been already touched before setting the policy,
+then the policy has no effect.
+This default behavior may be overridden by the
+.B MPOL_MF_MOVE
+and
+.B MPOL_MF_MOVE_ALL
+flags described below.
+.P
+The
+.I mode
+argument must specify one of
+.BR MPOL_DEFAULT ,
+.BR MPOL_BIND ,
+.BR MPOL_INTERLEAVE ,
+.BR MPOL_WEIGHTED_INTERLEAVE ,
+.BR MPOL_PREFERRED ,
+or
+.B MPOL_LOCAL
+(which are described in detail below).
+All policy modes except
+.B MPOL_DEFAULT
+require the caller to specify the node or nodes to which the mode applies,
+via the
+.I nodemask
+argument.
+.P
+The
+.I mode
+argument may also include an optional
+.IR "mode flag" .
+The supported
+.I "mode flags"
+are:
+.TP
+.BR MPOL_F_NUMA_BALANCING " (since Linux 5.15)"
+.\" commit bda420b985054a3badafef23807c4b4fa38a3dff
+.\" commit 6d2aec9e123bb9c49cb5c7fc654f25f81e688e8c
+When
+.I mode
+is
+.BR MPOL_BIND ,
+enable the kernel NUMA balancing for the task if it is supported by the kernel.
+If the flag isn't supported by the kernel, or is used with
+.I mode
+other than
+.BR MPOL_BIND ,
+\-1 is returned and
+.I errno
+is set to
+.BR EINVAL .
+.TP
+.BR MPOL_F_STATIC_NODES " (since Linux-2.6.26)"
+A nonempty
+.I nodemask
+specifies physical node IDs.
+Linux does not remap the
+.I nodemask
+when the thread moves to a different cpuset context,
+nor when the set of nodes allowed by the thread's
+current cpuset context changes.
+.TP
+.BR MPOL_F_RELATIVE_NODES " (since Linux-2.6.26)"
+A nonempty
+.I nodemask
+specifies node IDs that are relative to the set of
+node IDs allowed by the thread's current cpuset.
+.P
+.I nodemask
+points to a bit mask of nodes containing up to
+.I maxnode
+bits.
+The bit mask size is rounded to the next multiple of
+.IR "sizeof(unsigned long)" ,
+but the kernel will use bits only up to
+.IR maxnode .
+A NULL value of
+.I nodemask
+or a
+.I maxnode
+value of zero specifies the empty set of nodes.
+If the value of
+.I maxnode
+is zero,
+the
+.I nodemask
+argument is ignored.
+Where a
+.I nodemask
+is required, it must contain at least one node that is on-line,
+allowed by the thread's current cpuset context
+(unless the
+.B MPOL_F_STATIC_NODES
+mode flag is specified),
+and contains memory.
+.P
+The
+.I mode
+argument must include one of the following values:
+.TP
+.B MPOL_DEFAULT
+This mode requests that any nondefault policy be removed,
+restoring default behavior.
+When applied to a range of memory via
+.BR mbind (),
+this means to use the thread memory policy,
+which may have been set with
+.BR set_mempolicy (2).
+If the mode of the thread memory policy is also
+.BR MPOL_DEFAULT ,
+the system-wide default policy will be used.
+The system-wide default policy allocates
+pages on the node of the CPU that triggers the allocation.
+For
+.BR MPOL_DEFAULT ,
+the
+.I nodemask
+and
+.I maxnode
+arguments must be specify the empty set of nodes.
+.TP
+.B MPOL_BIND
+This mode specifies a strict policy that restricts memory allocation to
+the nodes specified in
+.IR nodemask .
+If
+.I nodemask
+specifies more than one node, page allocations will come from
+the node with sufficient free memory that is closest to
+the node where the allocation takes place.
+Pages will not be allocated from any node not specified in the
+IR nodemask .
+(Before Linux 2.6.26,
+.\" commit 19770b32609b6bf97a3dece2529089494cbfc549
+page allocations came from
+the node with the lowest numeric node ID first, until that node
+contained no free memory.
+Allocations then came from the node with the next highest
+node ID specified in
+.I nodemask
+and so forth, until none of the specified nodes contained free memory.)
+.TP
+.B MPOL_INTERLEAVE
+This mode specifies that page allocations be interleaved across the
+set of nodes specified in
+.IR nodemask .
+This optimizes for bandwidth instead of latency
+by spreading out pages and memory accesses to those pages across
+multiple nodes.
+To be effective the memory area should be fairly large,
+at least 1\ MB or bigger with a fairly uniform access pattern.
+Accesses to a single page of the area will still be limited to
+the memory bandwidth of a single node.
+.TP
+.BR MPOL_WEIGHTED_INTERLEAVE " (since Linux 6.9)"
+.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
+This mode interleaves page allocations across the nodes specified in
+.I nodemask
+according to the weights in
+.IR /sys/kernel/mm/mempolicy/weighted_interleave .
+For example, if bits 0, 2, and 5 are set in
+.IR nodemask ,
+and the contents of
+.IR /sys/kernel/mm/mempolicy/weighted_interleave/node0 ,
+.IR /sys/ .\|.\|. /node2 ,
+and
+.IR /sys/ .\|.\|. /node5
+are 4, 7, and 9, respectively,
+then pages in this region will be allocated on nodes 0, 2, and 5
+in a 4:7:9 ratio.
+.TP
+.B MPOL_PREFERRED
+This mode sets the preferred node for allocation.
+The kernel will try to allocate pages from this
+node first and fall back to other nodes if the
+preferred nodes is low on free memory.
+If
+.I nodemask
+specifies more than one node ID, the first node in the
+mask will be selected as the preferred node.
+If the
+.I nodemask
+and
+.I maxnode
+arguments specify the empty set, then the memory is allocated on
+the node of the CPU that triggered the allocation.
+.TP
+.BR MPOL_LOCAL " (since Linux 3.8)"
+.\" commit 479e2802d09f1e18a97262c4c6f8f17ae5884bd8
+.\" commit f2a07f40dbc603c15f8b06e6ec7f768af67b424f
+This mode specifies "local allocation"; the memory is allocated on
+the node of the CPU that triggered the allocation (the "local node").
+The
+.I nodemask
+and
+.I maxnode
+arguments must specify the empty set.
+If the "local node" is low on free memory,
+the kernel will try to allocate memory from other nodes.
+The kernel will allocate memory from the "local node"
+whenever memory for this node is available.
+If the "local node" is not allowed by the thread's current cpuset context,
+the kernel will try to allocate memory from other nodes.
+The kernel will allocate memory from the "local node" whenever
+it becomes allowed by the thread's current cpuset context.
+By contrast,
+.B MPOL_DEFAULT
+reverts to the memory policy of the thread (which may be set via
+.BR set_mempolicy (2));
+that policy may be something other than "local allocation".
+.P
+If
+.B MPOL_MF_STRICT
+is passed in
+.I flags
+and
+.I mode
+is not
+.BR MPOL_DEFAULT ,
+then the call fails with the error
+.B EIO
+if the existing pages in the memory range don't follow the policy.
+.\" According to the kernel code, the following is not true
+.\" --Lee Schermerhorn
+.\" In Linux 2.6.16 or later the kernel will also try to move pages
+.\" to the requested node with this flag.
+.P
+If
+.B MPOL_MF_MOVE
+is specified in
+.IR flags ,
+then the kernel will attempt to move all the existing pages
+in the memory range so that they follow the policy.
+Pages that are shared with other processes will not be moved.
+If
+.B MPOL_MF_STRICT
+is also specified, then the call fails with the error
+.B EIO
+if some pages could not be moved.
+If the
+.B MPOL_INTERLEAVE
+policy was specified,
+pages already residing on the specified nodes
+will not be moved such that they are interleaved.
+.P
+If
+.B MPOL_MF_MOVE_ALL
+is passed in
+.IR flags ,
+then the kernel will attempt to move all existing pages in the memory range
+regardless of whether other processes use the pages.
+The calling thread must be privileged
+.RB ( CAP_SYS_NICE )
+to use this flag.
+If
+.B MPOL_MF_STRICT
+is also specified, then the call fails with the error
+.B EIO
+if some pages could not be moved.
+If the
+.B MPOL_INTERLEAVE
+policy was specified,
+pages already residing on the specified nodes
+will not be moved such that they are interleaved.
+.\" ---------------------------------------------------------------
+.SH RETURN VALUE
+On success,
+.BR mbind ()
+returns 0;
+on error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.\" ---------------------------------------------------------------
+.SH ERRORS
+.\"  I think I got all of the error returns.  --Lee Schermerhorn
+.TP
+.B EFAULT
+Part or all of the memory range specified by
+.I nodemask
+and
+.I maxnode
+points outside your accessible address space.
+Or, there was an unmapped hole in the specified memory range specified by
+.I addr
+and
+.IR len .
+.TP
+.B EINVAL
+An invalid value was specified for
+.I flags
+or
+.IR mode ;
+or
+.I addr + len
+was less than
+.IR addr ;
+or
+.I addr
+is not a multiple of the system page size.
+Or,
+.I mode
+is
+.B MPOL_DEFAULT
+and
+.I nodemask
+specified a nonempty set;
+or
+.I mode
+is
+.B MPOL_BIND
+or
+.B MPOL_INTERLEAVE
+and
+.I nodemask
+is empty.
+Or,
+.I maxnode
+exceeds a kernel-imposed limit.
+.\" As at 2.6.23, this limit is "a page worth of bits", e.g.,
+.\" 8 * 4096 bits, assuming a 4kB page size.
+Or,
+.I nodemask
+specifies one or more node IDs that are
+greater than the maximum supported node ID.
+Or, none of the node IDs specified by
+.I nodemask
+are on-line and allowed by the thread's current cpuset context,
+or none of the specified nodes contain memory.
+Or, the
+.I mode
+argument specified both
+.B MPOL_F_STATIC_NODES
+and
+.BR MPOL_F_RELATIVE_NODES .
+.TP
+.B EIO
+.B MPOL_MF_STRICT
+was specified and an existing page was already on a node
+that does not follow the policy;
+or
+.B MPOL_MF_MOVE
+or
+.B MPOL_MF_MOVE_ALL
+was specified and the kernel was unable to move all existing
+pages in the range.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B EPERM
+The
+.I flags
+argument included the
+.B MPOL_MF_MOVE_ALL
+flag and the caller does not have the
+.B CAP_SYS_NICE
+privilege.
+.\" ---------------------------------------------------------------
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.7.
+.P
+Support for huge page policy was added with Linux 2.6.16.
+For interleave policy to be effective on huge page mappings the
+policied memory needs to be tens of megabytes or larger.
+.P
+Before Linux 5.7.
+.\" commit dcf1763546d76c372f3136c8d6b2b6e77f140cf0
+.B MPOL_MF_STRICT
+was ignored on huge page mappings.
+.P
+.B MPOL_MF_MOVE
+and
+.B MPOL_MF_MOVE_ALL
+are available only on Linux 2.6.16 and later.
+.SH NOTES
+For information on library support, see
+.BR numa (7).
+.P
+NUMA policy is not supported on a memory-mapped file range
+that was mapped with the
+.B MAP_SHARED
+flag.
+.P
+The
+.B MPOL_DEFAULT
+mode can have different effects for
+.BR mbind ()
+and
+.BR set_mempolicy (2).
+When
+.B MPOL_DEFAULT
+is specified for
+.BR set_mempolicy (2),
+the thread's memory policy reverts to the system default policy
+or local allocation.
+When
+.B MPOL_DEFAULT
+is specified for a range of memory using
+.BR mbind (),
+any pages subsequently allocated for that range will use
+the thread's memory policy, as set by
+.BR set_mempolicy (2).
+This effectively removes the explicit policy from the
+specified range, "falling back" to a possibly nondefault
+policy.
+To select explicit "local allocation" for a memory range,
+specify a
+.I mode
+of
+.B MPOL_LOCAL
+or
+.B MPOL_PREFERRED
+with an empty set of nodes.
+This method will work for
+.BR set_mempolicy (2),
+as well.
+.SH SEE ALSO
+.BR get_mempolicy (2),
+.BR getcpu (2),
+.BR mmap (2),
+.BR set_mempolicy (2),
+.BR shmat (2),
+.BR shmget (2),
+.BR numa (3),
+.BR cpuset (7),
+.BR numa (7),
+.BR numactl (8)
diff --git a/man/man2/membarrier.2 b/man/man2/membarrier.2
new file mode 100644
index 000000000..cd8029dd9
--- /dev/null
+++ b/man/man2/membarrier.2
@@ -0,0 +1,460 @@
+'\" t
+.\" Copyright 2015-2017 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH membarrier 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+membarrier \- issue memory barriers on a set of threads
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.P
+.BR "#include <linux/membarrier.h>" \
+" /* Definition of " MEMBARRIER_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_membarrier, int " cmd ", unsigned int " flags \
+", int " cpu_id );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR membarrier (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR membarrier ()
+system call helps reducing the overhead of the memory barrier
+instructions required to order memory accesses on multi-core systems.
+However, this system call is heavier than a memory barrier, so using it
+effectively is
+.I not
+as simple as replacing memory barriers with this
+system call, but requires understanding of the details below.
+.P
+Use of memory barriers needs to be done taking into account that a
+memory barrier always needs to be either matched with its memory barrier
+counterparts, or that the architecture's memory model doesn't require the
+matching barriers.
+.P
+There are cases where one side of the matching barriers (which we will
+refer to as "fast side") is executed much more often than the other
+(which we will refer to as "slow side").
+This is a prime target for the use of
+.BR membarrier ().
+The key idea is to replace, for these matching
+barriers, the fast-side memory barriers by simple compiler barriers,
+for example:
+.P
+.in +4n
+.EX
+asm volatile ("" : : : "memory")
+.EE
+.in
+.P
+and replace the slow-side memory barriers by calls to
+.BR membarrier ().
+.P
+This will add overhead to the slow side, and remove overhead from the
+fast side, thus resulting in an overall performance increase as long as
+the slow side is infrequent enough that the overhead of the
+.BR membarrier ()
+calls does not outweigh the performance gain on the fast side.
+.P
+The
+.I cmd
+argument is one of the following:
+.TP
+.BR MEMBARRIER_CMD_QUERY " (since Linux 4.3)"
+Query the set of supported commands.
+The return value of the call is a bit mask of supported
+commands.
+.BR MEMBARRIER_CMD_QUERY ,
+which has the value 0,
+is not itself included in this bit mask.
+This command is always supported (on kernels where
+.BR membarrier ()
+is provided).
+.TP
+.BR MEMBARRIER_CMD_GLOBAL " (since Linux 4.16)"
+Ensure that all threads from all processes on the system pass through a
+state where all memory accesses to user-space addresses match program
+order between entry to and return from the
+.BR membarrier ()
+system call.
+All threads on the system are targeted by this command.
+.TP
+.BR MEMBARRIER_CMD_GLOBAL_EXPEDITED " (since Linux 4.16)"
+Execute a memory barrier on all running threads of all processes that
+previously registered with
+.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED .
+.IP
+Upon return from the system call, the calling thread has a guarantee that all
+running threads have passed through a state where all memory accesses to
+user-space addresses match program order between entry to and return
+from the system call (non-running threads are de facto in such a state).
+This guarantee is provided only for the threads of processes that
+previously registered with
+.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED .
+.IP
+Given that registration is about the intent to receive the barriers, it
+is valid to invoke
+.B MEMBARRIER_CMD_GLOBAL_EXPEDITED
+from a process that has not employed
+.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED .
+.IP
+The "expedited" commands complete faster than the non-expedited ones;
+they never block, but have the downside of causing extra overhead.
+.TP
+.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED " (since Linux 4.16)"
+Register the process's intent to receive
+.B MEMBARRIER_CMD_GLOBAL_EXPEDITED
+memory barriers.
+.TP
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED " (since Linux 4.14)"
+Execute a memory barrier on each running thread belonging to the same
+process as the calling thread.
+.IP
+Upon return from the system call, the calling
+thread has a guarantee that all its running thread siblings have passed
+through a state where all memory accesses to user-space addresses match
+program order between entry to and return from the system call
+(non-running threads are de facto in such a state).
+This guarantee is provided only for threads in
+the same process as the calling thread.
+.IP
+The "expedited" commands complete faster than the non-expedited ones;
+they never block, but have the downside of causing extra overhead.
+.IP
+A process must register its intent to use the private
+expedited command prior to using it.
+.TP
+.BR MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED " (since Linux 4.14)"
+Register the process's intent to use
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED .
+.TP
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE " (since Linux 4.16)"
+In addition to providing the memory ordering guarantees described in
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED ,
+upon return from system call the calling thread has a guarantee that all its
+running thread siblings have executed a core serializing instruction.
+This guarantee is provided only for threads in
+the same process as the calling thread.
+.IP
+The "expedited" commands complete faster than the non-expedited ones,
+they never block, but have the downside of causing extra overhead.
+.IP
+A process must register its intent to use the private expedited sync
+core command prior to using it.
+.TP
+.BR MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE " (since Linux 4.16)"
+Register the process's intent to use
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE .
+.TP
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ " (since Linux 5.10)"
+Ensure the caller thread, upon return from system call, that all its
+running thread siblings have any currently running rseq critical sections
+restarted if
+.I flags
+parameter is 0; if
+.I flags
+parameter is
+.BR MEMBARRIER_CMD_FLAG_CPU ,
+then this operation is performed only on CPU indicated by
+.IR cpu_id .
+This guarantee is provided only for threads in
+the same process as the calling thread.
+.IP
+RSEQ membarrier is only available in the "private expedited" form.
+.IP
+A process must register its intent to use the private expedited rseq
+command prior to using it.
+.TP
+.BR MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ " (since Linux 5.10)"
+Register the process's intent to use
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ .
+.TP
+.BR MEMBARRIER_CMD_SHARED " (since Linux 4.3)"
+This is an alias for
+.B MEMBARRIER_CMD_GLOBAL
+that exists for header backward compatibility.
+.P
+The
+.I flags
+argument must be specified as 0 unless the command is
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ ,
+in which case
+.I flags
+can be either 0 or
+.BR MEMBARRIER_CMD_FLAG_CPU .
+.P
+The
+.I cpu_id
+argument is ignored unless
+.I flags
+is
+.BR MEMBARRIER_CMD_FLAG_CPU ,
+in which case it must specify the CPU targeted by this membarrier
+command.
+.P
+All memory accesses performed in program order from each targeted thread
+are guaranteed to be ordered with respect to
+.BR membarrier ().
+.P
+If we use the semantic
+.I barrier()
+to represent a compiler barrier forcing memory
+accesses to be performed in program order across the barrier, and
+.I smp_mb()
+to represent explicit memory barriers forcing full memory
+ordering across the barrier, we have the following ordering table for
+each pairing of
+.IR barrier() ,
+.BR membarrier (),
+and
+.IR smp_mb() .
+The pair ordering is detailed as (O: ordered, X: not ordered):
+.P
+.RS
+.TS
+l c c c.
+\&	barrier()	smp_mb()	membarrier()
+barrier()	X	X	O
+smp_mb()	X	O	O
+membarrier()	O	O	O
+.TE
+.RE
+.SH RETURN VALUE
+On success, the
+.B MEMBARRIER_CMD_QUERY
+operation returns a bit mask of supported commands, and the
+.BR MEMBARRIER_CMD_GLOBAL ,
+.BR MEMBARRIER_CMD_GLOBAL_EXPEDITED ,
+.BR MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED ,
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED ,
+.BR MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED ,
+.BR MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE ,
+and
+.B MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE
+operations return zero.
+On error, \-1 is returned,
+and
+.I errno
+is set to indicate the error.
+.P
+For a given command, with
+.I flags
+set to 0, this system call is
+guaranteed to always return the same value until reboot.
+Further calls with the same arguments will lead to the same result.
+Therefore, with
+.I flags
+set to 0, error handling is required only for the first call to
+.BR membarrier ().
+.SH ERRORS
+.TP
+.B EINVAL
+.I cmd
+is invalid, or
+.I flags
+is nonzero, or the
+.B MEMBARRIER_CMD_GLOBAL
+command is disabled because the
+.I nohz_full
+CPU parameter has been set, or the
+.B MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE
+and
+.B MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE
+commands are not implemented by the architecture.
+.TP
+.B ENOSYS
+The
+.BR membarrier ()
+system call is not implemented by this kernel.
+.TP
+.B EPERM
+The current process was not registered prior to using private expedited
+commands.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 4.3.
+.P
+Before Linux 5.10, the prototype was:
+.P
+.in +4n
+.EX
+.BI "int membarrier(int " cmd ", int " flags );
+.EE
+.in
+.SH NOTES
+A memory barrier instruction is part of the instruction set of
+architectures with weakly ordered memory models.
+It orders memory
+accesses prior to the barrier and after the barrier with respect to
+matching barriers on other cores.
+For instance, a load fence can order
+loads prior to and following that fence with respect to stores ordered
+by store fences.
+.P
+Program order is the order in which instructions are ordered in the
+program assembly code.
+.P
+Examples where
+.BR membarrier ()
+can be useful include implementations
+of Read-Copy-Update libraries and garbage collectors.
+.SH EXAMPLES
+Assuming a multithreaded application where "fast_path()" is executed
+very frequently, and where "slow_path()" is executed infrequently, the
+following code (x86) can be transformed using
+.BR membarrier ():
+.P
+.in +4n
+.\" SRC BEGIN (membarrier.c)
+.EX
+#include <stdlib.h>
+\&
+static volatile int a, b;
+\&
+static void
+fast_path(int *read_b)
+{
+    a = 1;
+    asm volatile ("mfence" : : : "memory");
+    *read_b = b;
+}
+\&
+static void
+slow_path(int *read_a)
+{
+    b = 1;
+    asm volatile ("mfence" : : : "memory");
+    *read_a = a;
+}
+\&
+int
+main(void)
+{
+    int read_a, read_b;
+\&
+    /*
+     * Real applications would call fast_path() and slow_path()
+     * from different threads. Call those from main() to keep
+     * this example short.
+     */
+\&
+    slow_path(&read_a);
+    fast_path(&read_b);
+\&
+    /*
+     * read_b == 0 implies read_a == 1 and
+     * read_a == 0 implies read_b == 1.
+     */
+\&
+    if (read_b == 0 && read_a == 0)
+        abort();
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.P
+The code above transformed to use
+.BR membarrier ()
+becomes:
+.P
+.in +4n
+.EX
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <linux/membarrier.h>
+\&
+static volatile int a, b;
+\&
+static int
+membarrier(int cmd, unsigned int flags, int cpu_id)
+{
+    return syscall(__NR_membarrier, cmd, flags, cpu_id);
+}
+\&
+static int
+init_membarrier(void)
+{
+    int ret;
+\&
+    /* Check that membarrier() is supported. */
+\&
+    ret = membarrier(MEMBARRIER_CMD_QUERY, 0, 0);
+    if (ret < 0) {
+        perror("membarrier");
+        return \-1;
+    }
+\&
+    if (!(ret & MEMBARRIER_CMD_GLOBAL)) {
+        fprintf(stderr,
+            "membarrier does not support MEMBARRIER_CMD_GLOBAL\en");
+        return \-1;
+    }
+\&
+    return 0;
+}
+\&
+static void
+fast_path(int *read_b)
+{
+    a = 1;
+    asm volatile ("" : : : "memory");
+    *read_b = b;
+}
+\&
+static void
+slow_path(int *read_a)
+{
+    b = 1;
+    membarrier(MEMBARRIER_CMD_GLOBAL, 0, 0);
+    *read_a = a;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int read_a, read_b;
+\&
+    if (init_membarrier())
+        exit(EXIT_FAILURE);
+\&
+    /*
+     * Real applications would call fast_path() and slow_path()
+     * from different threads. Call those from main() to keep
+     * this example short.
+     */
+\&
+    slow_path(&read_a);
+    fast_path(&read_b);
+\&
+    /*
+     * read_b == 0 implies read_a == 1 and
+     * read_a == 0 implies read_b == 1.
+     */
+\&
+    if (read_b == 0 && read_a == 0)
+        abort();
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.in
+.\" .SH SEE ALSO
+.\" FIXME See if the following syscalls make it into Linux 4.15 or later
+.\" .BR cpu_opv (2),
+.\" .BR rseq (2)
diff --git a/man/man2/memfd_create.2 b/man/man2/memfd_create.2
new file mode 100644
index 000000000..794aa0e54
--- /dev/null
+++ b/man/man2/memfd_create.2
@@ -0,0 +1,549 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2014 David Herrmann <dh.herrmann@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH memfd_create 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memfd_create \- create an anonymous file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <sys/mman.h>
+.P
+.BI "int memfd_create(const char *" name ", unsigned int " flags ");"
+.fi
+.SH DESCRIPTION
+.BR memfd_create ()
+creates an anonymous file and returns a file descriptor that refers to it.
+The file behaves like a regular file, and so can be modified,
+truncated, memory-mapped, and so on.
+However, unlike a regular file,
+it lives in RAM and has a volatile backing storage.
+Once all references to the file are dropped, it is automatically released.
+Anonymous memory is used for all backing pages of the file.
+Therefore, files created by
+.BR memfd_create ()
+have the same semantics as other anonymous
+.\" David Herrmann:
+.\"     memfd uses VM_NORESERVE so each page is accounted on first access.
+.\"     This means, the overcommit-limits (see __vm_enough_memory()) and the
+.\"     memory-cgroup limits (mem_cgroup_try_charge()) are applied. Note that
+.\"     those are accounted on "current" and "current->mm", that is, the
+.\"     process doing the first page access.
+memory allocations such as those allocated using
+.BR mmap (2)
+with the
+.B MAP_ANONYMOUS
+flag.
+.P
+The initial size of the file is set to 0.
+Following the call, the file size should be set using
+.BR ftruncate (2).
+(Alternatively, the file may be populated by calls to
+.BR write (2)
+or similar.)
+.P
+The name supplied in
+.I name
+is used as a filename and will be displayed
+as the target of the corresponding symbolic link in the directory
+.IR /proc/self/fd/ .
+The displayed name is always prefixed with
+.I memfd:
+and serves only for debugging purposes.
+Names do not affect the behavior of the file descriptor,
+and as such multiple files can have the same name without any side effects.
+.P
+The following values may be bitwise ORed in
+.I flags
+to change the behavior of
+.BR memfd_create ():
+.TP
+.B MFD_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.TP
+.B MFD_ALLOW_SEALING
+Allow sealing operations on this file.
+See the discussion of the
+.B F_ADD_SEALS
+and
+.B F_GET_SEALS
+operations in
+.BR fcntl (2),
+and also NOTES, below.
+The initial set of seals is empty.
+If this flag is not set, the initial set of seals will be
+.BR F_SEAL_SEAL ,
+meaning that no other seals can be set on the file.
+.\" FIXME Why is the MFD_ALLOW_SEALING behavior not simply the default?
+.\" Is it worth adding some text explaining this?
+.TP
+.BR MFD_HUGETLB " (since Linux 4.14)"
+.\" commit 749df87bd7bee5a79cef073f5d032ddb2b211de8
+The anonymous file will be created in the hugetlbfs filesystem using
+huge pages.
+See the Linux kernel source file
+.I Documentation/admin\-guide/mm/hugetlbpage.rst
+for more information about hugetlbfs.
+.\" commit 47b9012ecdc747f6936395265e677d41e11a31ff
+Specifying both
+.B MFD_HUGETLB
+and
+.B MFD_ALLOW_SEALING
+in
+.I flags
+is supported since Linux 4.16.
+.TP
+.B MFD_HUGE_2MB
+.TQ
+.B MFD_HUGE_1GB
+.TQ
+\&.\|.\|.
+Used in conjunction with
+.B MFD_HUGETLB
+to select alternative hugetlb page sizes (respectively, 2\ MB, 1\ GB, ...)
+on systems that support multiple hugetlb page sizes.
+Definitions for known
+huge page sizes are included in the header file
+.I <linux/memfd.h>.
+.IP
+For details on encoding huge page sizes not included in the header file,
+see the discussion of the similarly named constants in
+.BR mmap (2).
+.P
+Unused bits in
+.I flags
+must be 0.
+.P
+As its return value,
+.BR memfd_create ()
+returns a new file descriptor that can be used to refer to the file.
+This file descriptor is opened for both reading and writing
+.RB ( O_RDWR )
+and
+.B O_LARGEFILE
+is set for the file descriptor.
+.P
+With respect to
+.BR fork (2)
+and
+.BR execve (2),
+the usual semantics apply for the file descriptor created by
+.BR memfd_create ().
+A copy of the file descriptor is inherited by the child produced by
+.BR fork (2)
+and refers to the same file.
+The file descriptor is preserved across
+.BR execve (2),
+unless the close-on-exec flag has been set.
+.SH RETURN VALUE
+On success,
+.BR memfd_create ()
+returns a new file descriptor.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+The address in
+.I name
+points to invalid memory.
+.TP
+.B EINVAL
+.I flags
+included unknown bits.
+.TP
+.B EINVAL
+.I name
+was too long.
+(The limit is
+.\" NAME_MAX - strlen("memfd:")
+249 bytes, excluding the terminating null byte.)
+.TP
+.B EINVAL
+Both
+.B MFD_HUGETLB
+and
+.B MFD_ALLOW_SEALING
+were specified in
+.IR flags .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+There was insufficient memory to create a new anonymous file.
+.TP
+.B EPERM
+The
+.B MFD_HUGETLB
+flag was specified, but the caller was not privileged (did not have the
+.B CAP_IPC_LOCK
+capability)
+and is not a member of the
+.I sysctl_hugetlb_shm_group
+group; see the description of
+.I /proc/sys/vm/sysctl_hugetlb_shm_group
+in
+.BR proc (5).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.17,
+glibc 2.27.
+.SH NOTES
+.\" See also http://lwn.net/Articles/593918/
+.\" and http://lwn.net/Articles/594919/ and http://lwn.net/Articles/591108/
+The
+.BR memfd_create ()
+system call provides a simple alternative to manually mounting a
+.BR tmpfs (5)
+filesystem and creating and opening a file in that filesystem.
+The primary purpose of
+.BR memfd_create ()
+is to create files and associated file descriptors that are
+used with the file-sealing APIs provided by
+.BR fcntl (2).
+.P
+The
+.BR memfd_create ()
+system call also has uses without file sealing
+(which is why file-sealing is disabled, unless explicitly requested with the
+.B MFD_ALLOW_SEALING
+flag).
+In particular, it can be used as an alternative to creating files in
+.I tmp
+or as an alternative to using the
+.BR  open (2)
+.B O_TMPFILE
+in cases where there is no intention to actually link the
+resulting file into the filesystem.
+.SS File sealing
+In the absence of file sealing,
+processes that communicate via shared memory must either trust each other,
+or take measures to deal with the possibility that an untrusted peer
+may manipulate the shared memory region in problematic ways.
+For example, an untrusted peer might modify the contents of the
+shared memory at any time, or shrink the shared memory region.
+The former possibility leaves the local process vulnerable to
+time-of-check-to-time-of-use race conditions
+(typically dealt with by copying data from
+the shared memory region before checking and using it).
+The latter possibility leaves the local process vulnerable to
+.B SIGBUS
+signals when an attempt is made to access a now-nonexistent
+location in the shared memory region.
+(Dealing with this possibility necessitates the use of a handler for the
+.B SIGBUS
+signal.)
+.P
+Dealing with untrusted peers imposes extra complexity on
+code that employs shared memory.
+Memory sealing enables that extra complexity to be eliminated,
+by allowing a process to operate secure in the knowledge that
+its peer can't modify the shared memory in an undesired fashion.
+.P
+An example of the usage of the sealing mechanism is as follows:
+.IP (1) 5
+The first process creates a
+.BR tmpfs (5)
+file using
+.BR memfd_create ().
+The call yields a file descriptor used in subsequent steps.
+.IP (2)
+The first process
+sizes the file created in the previous step using
+.BR ftruncate (2),
+maps it using
+.BR mmap (2),
+and populates the shared memory with the desired data.
+.IP (3)
+The first process uses the
+.BR fcntl (2)
+.B F_ADD_SEALS
+operation to place one or more seals on the file,
+in order to restrict further modifications on the file.
+(If placing the seal
+.BR F_SEAL_WRITE ,
+then it will be necessary to first unmap the shared writable mapping
+created in the previous step.
+Otherwise, behavior similar to
+.B F_SEAL_WRITE
+can be achieved by using
+.BR F_SEAL_FUTURE_WRITE ,
+which will prevent future writes via
+.BR mmap (2)
+and
+.BR write (2)
+from succeeding while keeping existing shared writable mappings).
+.IP (4)
+A second process obtains a file descriptor for the
+.BR tmpfs (5)
+file and maps it.
+Among the possible ways in which this could happen are the following:
+.RS
+.IP \[bu] 3
+The process that called
+.BR memfd_create ()
+could transfer the resulting file descriptor to the second process
+via a UNIX domain socket (see
+.BR unix (7)
+and
+.BR cmsg (3)).
+The second process then maps the file using
+.BR mmap (2).
+.IP \[bu]
+The second process is created via
+.BR fork (2)
+and thus automatically inherits the file descriptor and mapping.
+(Note that in this case and the next,
+there is a natural trust relationship between the two processes,
+since they are running under the same user ID.
+Therefore, file sealing would not normally be necessary.)
+.IP \[bu]
+The second process opens the file
+.IR /proc/ pid /fd/ fd,
+where
+.I <pid>
+is the PID of the first process (the one that called
+.BR memfd_create ()),
+and
+.I <fd>
+is the number of the file descriptor returned by the call to
+.BR memfd_create ()
+in that process.
+The second process then maps the file using
+.BR mmap (2).
+.RE
+.IP (5)
+The second process uses the
+.BR fcntl (2)
+.B F_GET_SEALS
+operation to retrieve the bit mask of seals
+that has been applied to the file.
+This bit mask can be inspected in order to determine
+what kinds of restrictions have been placed on file modifications.
+If desired, the second process can apply further seals
+to impose additional restrictions (so long as the
+.B F_SEAL_SEAL
+seal has not yet been applied).
+.SH EXAMPLES
+Below are shown two example programs that demonstrate the use of
+.BR memfd_create ()
+and the file sealing API.
+.P
+The first program,
+.IR t_memfd_create.c ,
+creates a
+.BR tmpfs (5)
+file using
+.BR memfd_create (),
+sets a size for the file, maps it into memory,
+and optionally places some seals on the file.
+The program accepts up to three command-line arguments,
+of which the first two are required.
+The first argument is the name to associate with the file,
+the second argument is the size to be set for the file,
+and the optional third argument is a string of characters that specify
+seals to be set on the file.
+.P
+The second program,
+.IR t_get_seals.c ,
+can be used to open an existing file that was created via
+.BR memfd_create ()
+and inspect the set of seals that have been applied to that file.
+.P
+The following shell session demonstrates the use of these programs.
+First we create a
+.BR tmpfs (5)
+file and set some seals on it:
+.P
+.in +4n
+.EX
+$ \fB./t_memfd_create my_memfd_file 4096 sw &\fP
+[1] 11775
+PID: 11775; fd: 3; /proc/11775/fd/3
+.EE
+.in
+.P
+At this point, the
+.I t_memfd_create
+program continues to run in the background.
+From another program, we can obtain a file descriptor for the
+file created by
+.BR memfd_create ()
+by opening the
+.IR /proc/ pid /fd
+file that corresponds to the file descriptor opened by
+.BR memfd_create ().
+Using that pathname, we inspect the content of the
+.IR /proc/ pid /fd
+symbolic link, and use our
+.I t_get_seals
+program to view the seals that have been placed on the file:
+.P
+.in +4n
+.EX
+$ \fBreadlink /proc/11775/fd/3\fP
+/memfd:my_memfd_file (deleted)
+$ \fB./t_get_seals /proc/11775/fd/3\fP
+Existing seals: WRITE SHRINK
+.EE
+.in
+.SS Program source: t_memfd_create.c
+\&
+.\" SRC BEGIN (t_memfd_create.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int           fd;
+    char          *name, *seals_arg;
+    ssize_t       len;
+    unsigned int  seals;
+\&
+    if (argc < 3) {
+        fprintf(stderr, "%s name size [seals]\en", argv[0]);
+        fprintf(stderr, "\et\[aq]seals\[aq] can contain any of the "
+                "following characters:\en");
+        fprintf(stderr, "\et\etg \- F_SEAL_GROW\en");
+        fprintf(stderr, "\et\ets \- F_SEAL_SHRINK\en");
+        fprintf(stderr, "\et\etw \- F_SEAL_WRITE\en");
+        fprintf(stderr, "\et\etW \- F_SEAL_FUTURE_WRITE\en");
+        fprintf(stderr, "\et\etS \- F_SEAL_SEAL\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    name = argv[1];
+    len = atoi(argv[2]);
+    seals_arg = argv[3];
+\&
+    /* Create an anonymous file in tmpfs; allow seals to be
+       placed on the file. */
+\&
+    fd = memfd_create(name, MFD_ALLOW_SEALING);
+    if (fd == \-1)
+        err(EXIT_FAILURE, "memfd_create");
+\&
+    /* Size the file as specified on the command line. */
+\&
+    if (ftruncate(fd, len) == \-1)
+        err(EXIT_FAILURE, "truncate");
+\&
+    printf("PID: %jd; fd: %d; /proc/%jd/fd/%d\en",
+           (intmax_t) getpid(), fd, (intmax_t) getpid(), fd);
+\&
+    /* Code to map the file and populate the mapping with data
+       omitted. */
+\&
+    /* If a \[aq]seals\[aq] command\-line argument was supplied, set some
+       seals on the file. */
+\&
+    if (seals_arg != NULL) {
+        seals = 0;
+\&
+        if (strchr(seals_arg, \[aq]g\[aq]) != NULL)
+            seals |= F_SEAL_GROW;
+        if (strchr(seals_arg, \[aq]s\[aq]) != NULL)
+            seals |= F_SEAL_SHRINK;
+        if (strchr(seals_arg, \[aq]w\[aq]) != NULL)
+            seals |= F_SEAL_WRITE;
+        if (strchr(seals_arg, \[aq]W\[aq]) != NULL)
+            seals |= F_SEAL_FUTURE_WRITE;
+        if (strchr(seals_arg, \[aq]S\[aq]) != NULL)
+            seals |= F_SEAL_SEAL;
+\&
+        if (fcntl(fd, F_ADD_SEALS, seals) == \-1)
+            err(EXIT_FAILURE, "fcntl");
+    }
+\&
+    /* Keep running, so that the file created by memfd_create()
+       continues to exist. */
+\&
+    pause();
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SS Program source: t_get_seals.c
+\&
+.\" SRC BEGIN (t_get_seals.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int           fd;
+    unsigned int  seals;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "%s /proc/PID/fd/FD\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fd = open(argv[1], O_RDWR);
+    if (fd == \-1)
+        err(EXIT_FAILURE, "open");
+\&
+    seals = fcntl(fd, F_GET_SEALS);
+    if (seals == \-1)
+        err(EXIT_FAILURE, "fcntl");
+\&
+    printf("Existing seals:");
+    if (seals & F_SEAL_SEAL)
+        printf(" SEAL");
+    if (seals & F_SEAL_GROW)
+        printf(" GROW");
+    if (seals & F_SEAL_WRITE)
+        printf(" WRITE");
+    if (seals & F_SEAL_FUTURE_WRITE)
+        printf(" FUTURE_WRITE");
+    if (seals & F_SEAL_SHRINK)
+        printf(" SHRINK");
+    printf("\en");
+\&
+    /* Code to map the file and access the contents of the
+       resulting mapping omitted. */
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fcntl (2),
+.BR ftruncate (2),
+.BR memfd_secret (2),
+.BR mmap (2),
+.BR shmget (2),
+.BR shm_open (3)
diff --git a/man/man2/memfd_secret.2 b/man/man2/memfd_secret.2
new file mode 100644
index 000000000..5d2436cc5
--- /dev/null
+++ b/man/man2/memfd_secret.2
@@ -0,0 +1,204 @@
+.\" Copyright (c) 2021, IBM Corporation.
+.\" Written by Mike Rapoport <rppt@linux.ibm.com>
+.\"
+.\" Based on memfd_create(2) man page
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2014 David Herrmann <dh.herrmann@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH memfd_secret 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memfd_secret \- create an anonymous RAM-based file
+to access secret memory regions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.P
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_memfd_secret, unsigned int " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR memfd_secret (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR memfd_secret ()
+creates an anonymous RAM-based file and returns a file descriptor
+that refers to it.
+The file provides a way to create and access memory regions
+with stronger protection than usual RAM-based files and
+anonymous memory mappings.
+Once all open references to the file are closed,
+it is automatically released.
+The initial size of the file is set to 0.
+Following the call, the file size should be set using
+.BR ftruncate (2).
+.P
+The memory areas backing the file created with
+.BR memfd_secret (2)
+are visible only to the processes that have access to the file descriptor.
+The memory region is removed from the kernel page tables
+and only the page tables of the processes holding the file descriptor
+map the corresponding physical memory.
+(Thus, the pages in the region can't be accessed by the kernel itself,
+so that, for example, pointers to the region can't be passed to
+system calls.)
+.P
+The following values may be bitwise ORed in
+.I flags
+to control the behavior of
+.BR memfd_secret ():
+.TP
+.B FD_CLOEXEC
+Set the close-on-exec flag on the new file descriptor,
+which causes the region to be removed from the process on
+.BR execve (2).
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+.P
+As its return value,
+.BR memfd_secret ()
+returns a new file descriptor that refers to an anonymous file.
+This file descriptor is opened for both reading and writing
+.RB ( O_RDWR )
+and
+.B O_LARGEFILE
+is set for the file descriptor.
+.P
+With respect to
+.BR fork (2)
+and
+.BR execve (2),
+the usual semantics apply for the file descriptor created by
+.BR memfd_secret ().
+A copy of the file descriptor is inherited by the child produced by
+.BR fork (2)
+and refers to the same file.
+The file descriptor is preserved across
+.BR execve (2),
+unless the close-on-exec flag has been set.
+.P
+The memory region is locked into memory in the same way as with
+.BR mlock (2),
+so that it will never be written into swap,
+and hibernation is inhibited for as long as any
+.BR memfd_secret ()
+descriptions exist.
+However the implementation of
+.BR memfd_secret ()
+will not try to populate the whole range during the
+.BR mmap (2)
+call that attaches the region into the process's address space;
+instead, the pages are only actually allocated
+as they are faulted in.
+The amount of memory allowed for memory mappings
+of the file descriptor obeys the same rules as
+.BR mlock (2)
+and cannot exceed
+.BR RLIMIT_MEMLOCK .
+.SH RETURN VALUE
+On success,
+.BR memfd_secret ()
+returns a new file descriptor.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I flags
+included unknown bits.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B EMFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+There was insufficient memory to create a new anonymous file.
+.TP
+.B ENOSYS
+.BR memfd_secret ()
+is not implemented on this architecture,
+or has not been enabled on the kernel command-line with
+.BR secretmem_enable =1.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.14.
+.SH NOTES
+The
+.BR memfd_secret ()
+system call is designed to allow a user-space process
+to create a range of memory that is inaccessible to anybody else -
+kernel included.
+There is no 100% guarantee that kernel won't be able to access
+memory ranges backed by
+.BR memfd_secret ()
+in any circumstances, but nevertheless,
+it is much harder to exfiltrate data from these regions.
+.P
+.BR memfd_secret ()
+provides the following protections:
+.IP \[bu] 3
+Enhanced protection
+(in conjunction with all the other in-kernel attack prevention systems)
+against ROP attacks.
+Absence of any in-kernel primitive for accessing memory backed by
+.BR memfd_secret ()
+means that one-gadget ROP attack
+can't work to perform data exfiltration.
+The attacker would need to find enough ROP gadgets
+to reconstruct the missing page table entries,
+which significantly increases difficulty of the attack,
+especially when other protections like the kernel stack size limit
+and address space layout randomization are in place.
+.IP \[bu]
+Prevent cross-process user-space memory exposures.
+Once a region for a
+.BR memfd_secret ()
+memory mapping is allocated,
+the user can't accidentally pass it into the kernel
+to be transmitted somewhere.
+The memory pages in this region cannot be accessed via the direct map
+and they are disallowed in get_user_pages.
+.IP \[bu]
+Harden against exploited kernel flaws.
+In order to access memory areas backed by
+.BR memfd_secret (),
+a kernel-side attack would need to
+either walk the page tables and create new ones,
+or spawn a new privileged user-space process to perform
+secrets exfiltration using
+.BR ptrace (2).
+.P
+The way
+.BR memfd_secret ()
+allocates and locks the memory may impact overall system performance,
+therefore the system call is disabled by default and only available
+if the system administrator turned it on using
+"secretmem.enable=y" kernel parameter.
+.P
+To prevent potential data leaks of memory regions backed by
+.BR memfd_secret ()
+from a hybernation image,
+hybernation is prevented when there are active
+.BR memfd_secret ()
+users.
+.SH SEE ALSO
+.BR fcntl (2),
+.BR ftruncate (2),
+.BR mlock (2),
+.BR memfd_create (2),
+.BR mmap (2),
+.BR setrlimit (2)
diff --git a/man/man2/migrate_pages.2 b/man/man2/migrate_pages.2
new file mode 100644
index 000000000..3e96f0322
--- /dev/null
+++ b/man/man2/migrate_pages.2
@@ -0,0 +1,174 @@
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft-2-para
+.\"
+.\" Copyright 2009 Intel Corporation
+.\"                Author: Andi Kleen
+.\" Based on the move_pages manpage which was
+.\" This manpage is Copyright (C) 2006 Silicon Graphics, Inc.
+.\"                               Christoph Lameter
+.\"
+.TH migrate_pages 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+migrate_pages \- move all pages in a process to another set of nodes
+.SH LIBRARY
+NUMA (Non-Uniform Memory Access) policy library
+.RI ( libnuma ", " \-lnuma )
+.SH SYNOPSIS
+.nf
+.B #include <numaif.h>
+.P
+.BI "long migrate_pages(int " pid ", unsigned long " maxnode,
+.BI "                   const unsigned long *" old_nodes,
+.BI "                   const unsigned long *" new_nodes );
+.fi
+.SH DESCRIPTION
+.BR migrate_pages ()
+attempts to move all pages of the process
+.I pid
+that are in memory nodes
+.I old_nodes
+to the memory nodes in
+.IR new_nodes .
+Pages not located in any node in
+.I old_nodes
+will not be migrated.
+As far as possible,
+the kernel maintains the relative topology relationship inside
+.I old_nodes
+during the migration to
+.IR new_nodes .
+.P
+The
+.I old_nodes
+and
+.I new_nodes
+arguments are pointers to bit masks of node numbers, with up to
+.I maxnode
+bits in each mask.
+These masks are maintained as arrays of unsigned
+.I long
+integers (in the last
+.I long
+integer, the bits beyond those specified by
+.I maxnode
+are ignored).
+The
+.I maxnode
+argument is the maximum node number in the bit mask plus one (this is the same
+as in
+.BR mbind (2),
+but different from
+.BR select (2)).
+.P
+The
+.I pid
+argument is the ID of the process whose pages are to be moved.
+To move pages in another process,
+the caller must be privileged
+.RB ( CAP_SYS_NICE )
+or the real or effective user ID of the calling process must match the
+real or saved-set user ID of the target process.
+If
+.I pid
+is 0, then
+.BR migrate_pages ()
+moves pages of the calling process.
+.P
+Pages shared with another process will be moved only if the initiating
+process has the
+.B CAP_SYS_NICE
+privilege.
+.SH RETURN VALUE
+On success
+.BR migrate_pages ()
+returns the number of pages that could not be moved
+(i.e., a return of zero means that all pages were successfully moved).
+On error, it returns \-1, and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Part or all of the memory range specified by
+.IR old_nodes / new_nodes
+and
+.I maxnode
+points outside your accessible address space.
+.TP
+.B EINVAL
+The value specified by
+.I maxnode
+exceeds a kernel-imposed limit.
+.\" As at 3.5, this limit is "a page worth of bits", e.g.,
+.\" 8 * 4096 bits, assuming a 4kB page size.
+Or,
+.I old_nodes
+or
+.I new_nodes
+specifies one or more node IDs that are
+greater than the maximum supported node ID.
+Or, none of the node IDs specified by
+.I new_nodes
+are on-line and allowed by the process's current cpuset context,
+or none of the specified nodes contain memory.
+.TP
+.B EPERM
+Insufficient privilege
+.RB ( CAP_SYS_NICE )
+to move pages of the process specified by
+.IR pid ,
+or insufficient privilege
+.RB ( CAP_SYS_NICE )
+to access the specified target nodes.
+.TP
+.B ESRCH
+No process matching
+.I pid
+could be found.
+.\" FIXME Document the other errors that can occur for migrate_pages()
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.16.
+.SH NOTES
+For information on library support, see
+.BR numa (7).
+.P
+Use
+.BR get_mempolicy (2)
+with the
+.B MPOL_F_MEMS_ALLOWED
+flag to obtain the set of nodes that are allowed by
+the calling process's cpuset.
+Note that this information is subject to change at any
+time by manual or automatic reconfiguration of the cpuset.
+.P
+Use of
+.BR migrate_pages ()
+may result in pages whose location
+(node) violates the memory policy established for the
+specified addresses (see
+.BR mbind (2))
+and/or the specified process (see
+.BR set_mempolicy (2)).
+That is, memory policy does not constrain the destination
+nodes used by
+.BR migrate_pages ().
+.P
+The
+.I <numaif.h>
+header is not included with glibc, but requires installing
+.I libnuma\-devel
+or a similar package.
+.SH SEE ALSO
+.BR get_mempolicy (2),
+.BR mbind (2),
+.BR set_mempolicy (2),
+.BR numa (3),
+.BR numa_maps (5),
+.BR cpuset (7),
+.BR numa (7),
+.BR migratepages (8),
+.BR numastat (8)
+.P
+.I Documentation/vm/page_migration.rst
+in the Linux kernel source tree
diff --git a/man/man2/mincore.2 b/man/man2/mincore.2
new file mode 100644
index 000000000..bc34562dc
--- /dev/null
+++ b/man/man2/mincore.2
@@ -0,0 +1,158 @@
+.\" Copyright (C) 2001 Bert Hubert <ahu@ds9a.nl>
+.\" and Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created Sun Jun 3 17:23:32 2001 by bert hubert <ahu@ds9a.nl>
+.\" Slightly adapted, following comments by Hugh Dickins, aeb, 2001-06-04.
+.\" Modified, 20 May 2003, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified, 30 Apr 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2005-04-05 mtk, Fixed error descriptions
+.\" 	after message from <gordon.jin@intel.com>
+.\" 2007-01-08 mtk, rewrote various parts
+.\"
+.TH mincore 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mincore \- determine whether pages are resident in memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "int mincore(void " addr [. length "], size_t " length ", unsigned char *" vec );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mincore ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+.BR mincore ()
+returns a vector that indicates whether pages
+of the calling process's virtual memory are resident in core (RAM),
+and so will not cause a disk access (page fault) if referenced.
+The kernel returns residency information about the pages
+starting at the address
+.IR addr ,
+and continuing for
+.I length
+bytes.
+.P
+The
+.I addr
+argument must be a multiple of the system page size.
+The
+.I length
+argument need not be a multiple of the page size,
+but since residency information is returned for whole pages,
+.I length
+is effectively rounded up to the next multiple of the page size.
+One may obtain the page size
+.RB ( PAGE_SIZE )
+using
+.IR sysconf(_SC_PAGESIZE) .
+.P
+The
+.I vec
+argument must point to an array containing at least
+.I "(length+PAGE_SIZE\-1) / PAGE_SIZE"
+bytes.
+On return,
+the least significant bit of each byte will be set if
+the corresponding page is currently resident in memory,
+and be clear otherwise.
+(The settings of the other bits in each byte are undefined;
+these bits are reserved for possible later use.)
+Of course the information returned in
+.I vec
+is only a snapshot: pages that are not
+locked in memory can come and go at any moment, and the contents of
+.I vec
+may already be stale by the time this call returns.
+.SH RETURN VALUE
+On success,
+.BR mincore ()
+returns zero.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.B EAGAIN
+kernel is temporarily out of resources.
+.TP
+.B EFAULT
+.I vec
+points to an invalid address.
+.TP
+.B EINVAL
+.I addr
+is not a multiple of the page size.
+.TP
+.B ENOMEM
+.I length
+is greater than
+.RI ( TASK_SIZE " \- " addr ).
+(This could occur if a negative value is specified for
+.IR length ,
+since that value will be interpreted as a large
+unsigned integer.)
+In Linux 2.6.11 and earlier, the error
+.B EINVAL
+was returned for this condition.
+.TP
+.B ENOMEM
+.I addr
+to
+.I addr
++
+.I length
+contained unmapped memory.
+.SH STANDARDS
+None.
+.SH HISTORY
+Linux 2.3.99pre1,
+glibc 2.2.
+.P
+First appeared in 4.4BSD.
+.P
+NetBSD, FreeBSD, OpenBSD, Solaris 8,
+AIX 5.1, SunOS 4.1.
+.SH BUGS
+Before Linux 2.6.21,
+.BR mincore ()
+did not return correct information for
+.B MAP_PRIVATE
+mappings, or for nonlinear mappings (established using
+.BR remap_file_pages (2)).
+.\" Linux (up to now, 2.6.5),
+.\" .B mincore
+.\" does not return correct information for MAP_PRIVATE mappings:
+.\" for a MAP_PRIVATE file mapping,
+.\" .B mincore
+.\" returns the residency of the file pages, rather than any
+.\" modified process-private pages that have been copied on write;
+.\" for a MAP_PRIVATE mapping of
+.\" .IR /dev/zero ,
+.\" .B mincore
+.\" always reports pages as nonresident;
+.\" and for a MAP_PRIVATE, MAP_ANONYMOUS mapping,
+.\" .B mincore
+.\" always fails with the error
+.\" .BR ENOMEM .
+.SH SEE ALSO
+.BR fincore (1),
+.BR madvise (2),
+.BR mlock (2),
+.BR mmap (2),
+.BR posix_fadvise (2),
+.BR posix_madvise (3)
diff --git a/man/man2/mkdir.2 b/man/man2/mkdir.2
new file mode 100644
index 000000000..1d9cddbe6
--- /dev/null
+++ b/man/man2/mkdir.2
@@ -0,0 +1,250 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt
+.\"             and Copyright (C) 1993,1994 Ian Jackson
+.\"		and Copyright (C) 2006, 2014 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH mkdir 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mkdir, mkdirat \- create a directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/stat.h>
+.\" .B #include <unistd.h>
+.P
+.BI "int mkdir(const char *" pathname ", mode_t " mode );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of AT_* constants */"
+.B #include <sys/stat.h>
+.P
+.BI "int mkdirat(int " dirfd ", const char *" pathname ", mode_t " mode );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mkdirat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+.BR mkdir ()
+attempts to create a directory named
+.IR pathname .
+.P
+The argument
+.I mode
+specifies the mode for the new directory (see
+.BR inode (7)).
+It is modified by the process's
+.I umask
+in the usual way: in the absence of a default ACL, the mode of the
+created directory is
+.RI ( mode " & \[ti]" umask " & 0777)."
+Whether other
+.I mode
+bits are honored for the created directory depends on the operating system.
+For Linux, see NOTES below.
+.P
+The newly created directory will be owned by the effective user ID of the
+process.
+If the directory containing the file has the set-group-ID
+bit set, or if the filesystem is mounted with BSD group semantics
+.RI ( "mount \-o bsdgroups"
+or, synonymously
+.IR "mount \-o grpid" ),
+the new directory will inherit the group ownership from its parent;
+otherwise it will be owned by the effective group ID of the process.
+.P
+If the parent directory has the set-group-ID bit set, then so will the
+newly created directory.
+.\"
+.\"
+.SS mkdirat()
+The
+.BR mkdirat ()
+system call operates in exactly the same way as
+.BR mkdir (),
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR mkdir ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR mkdir ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR mkdirat ().
+.SH RETURN VALUE
+.BR mkdir ()
+and
+.BR mkdirat ()
+return zero on success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The parent directory does not allow write permission to the process,
+or one of the directories in
+.I pathname
+did not allow search permission.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( mkdirat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EDQUOT
+The user's quota of disk blocks or inodes on the filesystem has been
+exhausted.
+.TP
+.B EEXIST
+.I pathname
+already exists (not necessarily as a directory).
+This includes the case where
+.I pathname
+is a symbolic link, dangling or not.
+.TP
+.B EFAULT
+.IR pathname " points outside your accessible address space."
+.TP
+.B EINVAL
+The final component ("basename") of the new directory's
+.I pathname
+is invalid
+(e.g., it contains characters not permitted by the underlying filesystem).
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B EMLINK
+The number of links to the parent directory would exceed
+.BR LINK_MAX .
+.TP
+.B ENAMETOOLONG
+.IR pathname " was too long."
+.TP
+.B ENOENT
+A directory component in
+.I pathname
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSPC
+The device containing
+.I pathname
+has no room for the new directory.
+.TP
+.B ENOSPC
+The new directory cannot be created because the user's disk quota is
+exhausted.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.I pathname
+is not, in fact, a directory.
+.TP
+.B ENOTDIR
+.RB ( mkdirat ())
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EPERM
+The filesystem containing
+.I pathname
+does not support the creation of directories.
+.TP
+.B EROFS
+.I pathname
+refers to a file on a read-only filesystem.
+.SH VERSIONS
+Under Linux, apart from the permission bits, the
+.B S_ISVTX
+.I mode
+bit is also honored.
+.SS glibc notes
+On older kernels where
+.BR mkdirat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR mkdir ().
+When
+.I pathname
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.I /proc/self/fd
+that corresponds to the
+.I dirfd
+argument.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR mkdir ()
+SVr4, BSD, POSIX.1-2001.
+.\" SVr4 documents additional EIO, EMULTIHOP
+.TP
+.BR mkdirat ()
+Linux 2.6.16,
+glibc 2.4.
+.SH NOTES
+There are many infelicities in the protocol underlying NFS.
+Some of these affect
+.BR mkdir ().
+.SH SEE ALSO
+.BR mkdir (1),
+.BR chmod (2),
+.BR chown (2),
+.BR mknod (2),
+.BR mount (2),
+.BR rmdir (2),
+.BR stat (2),
+.BR umask (2),
+.BR unlink (2),
+.BR acl (5),
+.BR path_resolution (7)
diff --git a/man/man2/mkdirat.2 b/man/man2/mkdirat.2
new file mode 100644
index 000000000..467b98a8b
--- /dev/null
+++ b/man/man2/mkdirat.2
@@ -0,0 +1 @@
+.so man2/mkdir.2
diff --git a/man/man2/mknod.2 b/man/man2/mknod.2
new file mode 100644
index 000000000..86b3b8c4f
--- /dev/null
+++ b/man/man2/mknod.2
@@ -0,0 +1,302 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt
+.\"             and Copyright (C) 1993,1994 Ian Jackson
+.\"		and Copyright (C) 2006, 2014, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Modified 1996-08-18 by urs
+.\" Modified 2003-04-23 by Michael Kerrisk
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH mknod 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mknod, mknodat \- create a special or ordinary file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/stat.h>
+.P
+.BI "int mknod(const char *" pathname ", mode_t " mode ", dev_t " dev );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of AT_* constants */"
+.B #include <sys/stat.h>
+.P
+.BI "int mknodat(int " dirfd ", const char *" pathname ", mode_t " mode \
+", dev_t " dev );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mknod ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The system call
+.BR mknod ()
+creates a filesystem node (file, device special file, or
+named pipe) named
+.IR pathname ,
+with attributes specified by
+.I mode
+and
+.IR dev .
+.P
+The
+.I mode
+argument specifies both the file mode to use and the type of node
+to be created.
+It should be a combination (using bitwise OR) of one of the file types
+listed below and zero or more of the file mode bits listed in
+.BR inode (7).
+.P
+The file mode is modified by the process's
+.I umask
+in the usual way: in the absence of a default ACL, the permissions of the
+created node are
+.RI ( mode " & \[ti]" umask ).
+.P
+The file type must be one of
+.BR S_IFREG ,
+.BR S_IFCHR ,
+.BR S_IFBLK ,
+.BR S_IFIFO ,
+or
+.B S_IFSOCK
+.\" (S_IFSOCK since Linux 1.2.4)
+to specify a regular file (which will be created empty), character
+special file, block special file, FIFO (named pipe), or UNIX domain socket,
+respectively.
+(Zero file type is equivalent to type
+.BR S_IFREG .)
+.P
+If the file type is
+.B S_IFCHR
+or
+.BR S_IFBLK ,
+then
+.I dev
+specifies the major and minor numbers of the newly created device
+special file
+.RB ( makedev (3)
+may be useful to build the value for
+.IR dev );
+otherwise it is ignored.
+.P
+If
+.I pathname
+already exists, or is a symbolic link, this call fails with an
+.B EEXIST
+error.
+.P
+The newly created node will be owned by the effective user ID of the
+process.
+If the directory containing the node has the set-group-ID
+bit set, or if the filesystem is mounted with BSD group semantics, the
+new node will inherit the group ownership from its parent directory;
+otherwise it will be owned by the effective group ID of the process.
+.\"
+.\"
+.SS mknodat()
+The
+.BR mknodat ()
+system call operates in exactly the same way as
+.BR mknod (),
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR mknod ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR mknod ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR mknodat ().
+.SH RETURN VALUE
+.BR mknod ()
+and
+.BR mknodat ()
+return zero on success.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The parent directory does not allow write permission to the process,
+or one of the directories in the path prefix of
+.I pathname
+did not allow search permission.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( mknodat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EDQUOT
+The user's quota of disk blocks or inodes on the filesystem has been
+exhausted.
+.TP
+.B EEXIST
+.I pathname
+already exists.
+This includes the case where
+.I pathname
+is a symbolic link, dangling or not.
+.TP
+.B EFAULT
+.IR pathname " points outside your accessible address space."
+.TP
+.B EINVAL
+.I mode
+requested creation of something other than a regular file, device
+special file, FIFO or socket.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B ENAMETOOLONG
+.IR pathname " was too long."
+.TP
+.B ENOENT
+A directory component in
+.I pathname
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSPC
+The device containing
+.I pathname
+has no room for the new node.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.I pathname
+is not, in fact, a directory.
+.TP
+.B ENOTDIR
+.RB ( mknodat ())
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EPERM
+.I mode
+requested creation of something other than a regular file,
+FIFO (named pipe), or UNIX domain socket, and the caller
+is not privileged (Linux: does not have the
+.B CAP_MKNOD
+capability);
+.\" For UNIX domain sockets and regular files, EPERM is returned only in
+.\" Linux 2.2 and earlier; in Linux 2.4 and later, unprivileged can
+.\" use mknod() to make these files.
+also returned if the filesystem containing
+.I pathname
+does not support the type of node requested.
+.TP
+.B EROFS
+.I pathname
+refers to a file on a read-only filesystem.
+.SH VERSIONS
+POSIX.1-2001 says: "The only portable use of
+.BR mknod ()
+is to create a FIFO-special file.
+If
+.I mode
+is not
+.B S_IFIFO
+or
+.I dev
+is not 0, the behavior of
+.BR mknod ()
+is unspecified."
+However, nowadays one should never use
+.BR mknod ()
+for this purpose; one should use
+.BR mkfifo (3),
+a function especially defined for this purpose.
+.P
+Under Linux,
+.BR mknod ()
+cannot be used to create directories.
+One should make directories with
+.BR mkdir (2).
+.\" and one should make UNIX domain sockets with socket(2) and bind(2).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR mknod ()
+SVr4, 4.4BSD, POSIX.1-2001 (but see VERSIONS).
+.\" The Linux version differs from the SVr4 version in that it
+.\" does not require root permission to create pipes, also in that no
+.\" EMULTIHOP, ENOLINK, or EINTR error is documented.
+.TP
+.BR mknodat ()
+Linux 2.6.16,
+glibc 2.4.
+POSIX.1-2008.
+.SH NOTES
+There are many infelicities in the protocol underlying NFS.
+Some of these affect
+.BR mknod ()
+and
+.BR mknodat ().
+.SH SEE ALSO
+.BR mknod (1),
+.BR chmod (2),
+.BR chown (2),
+.BR fcntl (2),
+.BR mkdir (2),
+.BR mount (2),
+.BR socket (2),
+.BR stat (2),
+.BR umask (2),
+.BR unlink (2),
+.BR makedev (3),
+.BR mkfifo (3),
+.BR acl (5),
+.BR path_resolution (7)
diff --git a/man/man2/mknodat.2 b/man/man2/mknodat.2
new file mode 100644
index 000000000..3db228243
--- /dev/null
+++ b/man/man2/mknodat.2
@@ -0,0 +1 @@
+.so man2/mknod.2
diff --git a/man/man2/mlock.2 b/man/man2/mlock.2
new file mode 100644
index 000000000..30f6ac130
--- /dev/null
+++ b/man/man2/mlock.2
@@ -0,0 +1,507 @@
+.\" Copyright (C) Michael Kerrisk, 2004
+.\"	using some material drawn from earlier man pages
+.\"	written by Thomas Kuhn, Copyright 1996
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH mlock 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mlock, mlock2, munlock, mlockall, munlockall \- lock and unlock memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "int mlock(const void " addr [. len "], size_t " len );
+.BI "int mlock2(const void " addr [. len "], size_t " len ", \
+unsigned int " flags );
+.BI "int munlock(const void " addr [. len "], size_t " len );
+.P
+.BI "int mlockall(int " flags );
+.B int munlockall(void);
+.fi
+.SH DESCRIPTION
+.BR mlock (),
+.BR mlock2 (),
+and
+.BR mlockall ()
+lock part or all of the calling process's virtual address
+space into RAM, preventing that memory from being paged to the
+swap area.
+.P
+.BR munlock ()
+and
+.BR munlockall ()
+perform the converse operation,
+unlocking part or all of the calling process's virtual address space,
+so that pages in the specified virtual address range
+can be swapped out again if required by the kernel memory manager.
+.P
+Memory locking and unlocking are performed in units of whole pages.
+.SS mlock(), mlock2(), and munlock()
+.BR mlock ()
+locks pages in the address range starting at
+.I addr
+and continuing for
+.I len
+bytes.
+All pages that contain a part of the specified address range are
+guaranteed to be resident in RAM when the call returns successfully;
+the pages are guaranteed to stay in RAM until later unlocked.
+.P
+.BR mlock2 ()
+.\" commit a8ca5d0ecbdde5cc3d7accacbd69968b0c98764e
+.\" commit de60f5f10c58d4f34b68622442c0e04180367f3f
+.\" commit b0f205c2a3082dd9081f9a94e50658c5fa906ff1
+also locks pages in the specified range starting at
+.I addr
+and continuing for
+.I len
+bytes.
+However, the state of the pages contained in that range after the call
+returns successfully will depend on the value in the
+.I flags
+argument.
+.P
+The
+.I flags
+argument can be either 0 or the following constant:
+.TP
+.B MLOCK_ONFAULT
+Lock pages that are currently resident and mark the entire range so
+that the remaining nonresident pages are locked when they are populated
+by a page fault.
+.P
+If
+.I flags
+is 0,
+.BR mlock2 ()
+behaves exactly the same as
+.BR mlock ().
+.P
+.BR munlock ()
+unlocks pages in the address range starting at
+.I addr
+and continuing for
+.I len
+bytes.
+After this call, all pages that contain a part of the specified
+memory range can be moved to external swap space again by the kernel.
+.SS mlockall() and munlockall()
+.BR mlockall ()
+locks all pages mapped into the address space of the
+calling process.
+This includes the pages of the code, data, and stack
+segment, as well as shared libraries, user space kernel data, shared
+memory, and memory-mapped files.
+All mapped pages are guaranteed
+to be resident in RAM when the call returns successfully;
+the pages are guaranteed to stay in RAM until later unlocked.
+.P
+The
+.I flags
+argument is constructed as the bitwise OR of one or more of the
+following constants:
+.TP
+.B MCL_CURRENT
+Lock all pages which are currently mapped into the address space of
+the process.
+.TP
+.B MCL_FUTURE
+Lock all pages which will become mapped into the address space of the
+process in the future.
+These could be, for instance, new pages required
+by a growing heap and stack as well as new memory-mapped files or
+shared memory regions.
+.TP
+.BR MCL_ONFAULT " (since Linux 4.4)"
+Used together with
+.BR MCL_CURRENT ,
+.BR MCL_FUTURE ,
+or both.
+Mark all current (with
+.BR MCL_CURRENT )
+or future (with
+.BR MCL_FUTURE )
+mappings to lock pages when they are faulted in.
+When used with
+.BR MCL_CURRENT ,
+all present pages are locked, but
+.BR mlockall ()
+will not fault in non-present pages.
+When used with
+.BR MCL_FUTURE ,
+all future mappings will be marked to lock pages when they are faulted
+in, but they will not be populated by the lock when the mapping is
+created.
+.B MCL_ONFAULT
+must be used with either
+.B MCL_CURRENT
+or
+.B MCL_FUTURE
+or both.
+.P
+If
+.B MCL_FUTURE
+has been specified, then a later system call (e.g.,
+.BR mmap (2),
+.BR sbrk (2),
+.BR malloc (3)),
+may fail if it would cause the number of locked bytes to exceed
+the permitted maximum (see below).
+In the same circumstances, stack growth may likewise fail:
+the kernel will deny stack expansion and deliver a
+.B SIGSEGV
+signal to the process.
+.P
+.BR munlockall ()
+unlocks all pages mapped into the address space of the
+calling process.
+.SH RETURN VALUE
+On success, these system calls return 0.
+On error, \-1 is returned,
+.I errno
+is set to indicate the error,
+and no changes are made to any locks in the
+address space of the process.
+.SH ERRORS
+.\"SVr4 documents an additional EAGAIN error code.
+.TP
+.B EAGAIN
+.RB ( mlock (),
+.BR mlock2 (),
+and
+.BR munlock ())
+Some or all of the specified address range could not be locked.
+.TP
+.B EINVAL
+.RB ( mlock (),
+.BR mlock2 (),
+and
+.BR munlock ())
+The result of the addition
+.IR addr + len
+was less than
+.I addr
+(e.g., the addition may have resulted in an overflow).
+.TP
+.B EINVAL
+.RB ( mlock2 ())
+Unknown \fIflags\fP were specified.
+.TP
+.B EINVAL
+.RB ( mlockall ())
+Unknown \fIflags\fP were specified or
+.B MCL_ONFAULT
+was specified without either
+.B MCL_FUTURE
+or
+.BR MCL_CURRENT .
+.TP
+.B EINVAL
+(Not on Linux)
+.I addr
+was not a multiple of the page size.
+.TP
+.B ENOMEM
+.RB ( mlock (),
+.BR mlock2 (),
+and
+.BR munlock ())
+Some of the specified address range does not correspond to mapped
+pages in the address space of the process.
+.TP
+.B ENOMEM
+.RB ( mlock (),
+.BR mlock2 (),
+and
+.BR munlock ())
+Locking or unlocking a region would result in the total number of
+mappings with distinct attributes (e.g., locked versus unlocked)
+exceeding the allowed maximum.
+.\" I.e., the number of VMAs would exceed the 64kB maximum
+(For example, unlocking a range in the middle of a currently locked
+mapping would result in three mappings:
+two locked mappings at each end and an unlocked mapping in the middle.)
+.TP
+.B ENOMEM
+(Linux 2.6.9 and later) the caller had a nonzero
+.B RLIMIT_MEMLOCK
+soft resource limit, but tried to lock more memory than the limit
+permitted.
+This limit is not enforced if the process is privileged
+.RB ( CAP_IPC_LOCK ).
+.TP
+.B ENOMEM
+(Linux 2.4 and earlier) the calling process tried to lock more than
+half of RAM.
+.\" In the case of mlock(), this check is somewhat buggy: it doesn't
+.\" take into account whether the to-be-locked range overlaps with
+.\" already locked pages.  Thus, suppose we allocate
+.\" (num_physpages / 4 + 1) of memory, and lock those pages once using
+.\" mlock(), and then lock the *same* page range a second time.
+.\" In the case, the second mlock() call will fail, since the check
+.\" calculates that the process is trying to lock (num_physpages / 2 + 2)
+.\" pages, which of course is not true.  (MTK, Nov 04, kernel 2.4.28)
+.TP
+.B EPERM
+The caller is not privileged, but needs privilege
+.RB ( CAP_IPC_LOCK )
+to perform the requested operation.
+.TP
+.B EPERM
+.RB ( munlockall ())
+(Linux 2.6.8 and earlier) The caller was not privileged
+.RB ( CAP_IPC_LOCK ).
+.SH VERSIONS
+.SS Linux
+Under Linux,
+.BR mlock (),
+.BR mlock2 (),
+and
+.BR munlock ()
+automatically round
+.I addr
+down to the nearest page boundary.
+However, the POSIX.1 specification of
+.BR mlock ()
+and
+.BR munlock ()
+allows an implementation to require that
+.I addr
+is page aligned, so portable applications should ensure this.
+.P
+The
+.I VmLck
+field of the Linux-specific
+.IR /proc/ pid /status
+file shows how many kilobytes of memory the process with ID
+.I PID
+has locked using
+.BR mlock (),
+.BR mlock2 (),
+.BR mlockall (),
+and
+.BR mmap (2)
+.BR MAP_LOCKED .
+.SH STANDARDS
+.TP
+.BR mlock ()
+.TQ
+.BR munlock ()
+.TQ
+.BR mlockall ()
+.TQ
+.BR munlockall ()
+POSIX.1-2008.
+.TP
+.BR mlock2 ()
+Linux.
+.P
+On POSIX systems on which
+.BR mlock ()
+and
+.BR munlock ()
+are available,
+.B _POSIX_MEMLOCK_RANGE
+is defined in \fI<unistd.h>\fP and the number of bytes in a page
+can be determined from the constant
+.B PAGESIZE
+(if defined) in \fI<limits.h>\fP or by calling
+.IR sysconf(_SC_PAGESIZE) .
+.P
+On POSIX systems on which
+.BR mlockall ()
+and
+.BR munlockall ()
+are available,
+.B _POSIX_MEMLOCK
+is defined in \fI<unistd.h>\fP to a value greater than 0.
+(See also
+.BR sysconf (3).)
+.\" POSIX.1-2001: It shall be defined to -1 or 0 or 200112L.
+.\" -1: unavailable, 0: ask using sysconf().
+.\" glibc defines it to 1.
+.SH HISTORY
+.TP
+.BR mlock ()
+.TQ
+.BR munlock ()
+.TQ
+.BR mlockall ()
+.TQ
+.BR munlockall ()
+POSIX.1-2001, POSIX.1-2008, SVr4.
+.TP
+.BR mlock2 ()
+Linux 4.4,
+glibc 2.27.
+.SH NOTES
+Memory locking has two main applications: real-time algorithms and
+high-security data processing.
+Real-time applications require
+deterministic timing, and, like scheduling, paging is one major cause
+of unexpected program execution delays.
+Real-time applications will
+usually also switch to a real-time scheduler with
+.BR sched_setscheduler (2).
+Cryptographic security software often handles critical bytes like
+passwords or secret keys as data structures.
+As a result of paging,
+these secrets could be transferred onto a persistent swap store medium,
+where they might be accessible to the enemy long after the security
+software has erased the secrets in RAM and terminated.
+(But be aware that the suspend mode on laptops and some desktop
+computers will save a copy of the system's RAM to disk, regardless
+of memory locks.)
+.P
+Real-time processes that are using
+.BR mlockall ()
+to prevent delays on page faults should reserve enough
+locked stack pages before entering the time-critical section,
+so that no page fault can be caused by function calls.
+This can be achieved by calling a function that allocates a
+sufficiently large automatic variable (an array) and writes to the
+memory occupied by this array in order to touch these stack pages.
+This way, enough pages will be mapped for the stack and can be
+locked into RAM.
+The dummy writes ensure that not even copy-on-write
+page faults can occur in the critical section.
+.P
+Memory locks are not inherited by a child created via
+.BR fork (2)
+and are automatically removed (unlocked) during an
+.BR execve (2)
+or when the process terminates.
+The
+.BR mlockall ()
+.B MCL_FUTURE
+and
+.B MCL_FUTURE | MCL_ONFAULT
+settings are not inherited by a child created via
+.BR fork (2)
+and are cleared during an
+.BR execve (2).
+.P
+Note that
+.BR fork (2)
+will prepare the address space for a copy-on-write operation.
+The consequence is that any write access that follows will cause
+a page fault that in turn may cause high latencies for a real-time process.
+Therefore, it is crucial not to invoke
+.BR fork (2)
+after an
+.BR mlockall ()
+or
+.BR mlock ()
+operation\[em]not even from a thread which runs at a low priority within
+a process which also has a thread running at elevated priority.
+.P
+The memory lock on an address range is automatically removed
+if the address range is unmapped via
+.BR munmap (2).
+.P
+Memory locks do not stack, that is, pages which have been locked several times
+by calls to
+.BR mlock (),
+.BR mlock2 (),
+or
+.BR mlockall ()
+will be unlocked by a single call to
+.BR munlock ()
+for the corresponding range or by
+.BR munlockall ().
+Pages which are mapped to several locations or by several processes stay
+locked into RAM as long as they are locked at least at one location or by
+at least one process.
+.P
+If a call to
+.BR mlockall ()
+which uses the
+.B MCL_FUTURE
+flag is followed by another call that does not specify this flag, the
+changes made by the
+.B MCL_FUTURE
+call will be lost.
+.P
+The
+.BR mlock2 ()
+.B MLOCK_ONFAULT
+flag and the
+.BR mlockall ()
+.B MCL_ONFAULT
+flag allow efficient memory locking for applications that deal with
+large mappings where only a (small) portion of pages in the mapping are touched.
+In such cases, locking all of the pages in a mapping would incur
+a significant penalty for memory locking.
+.SS Limits and permissions
+In Linux 2.6.8 and earlier,
+a process must be privileged
+.RB ( CAP_IPC_LOCK )
+in order to lock memory and the
+.B RLIMIT_MEMLOCK
+soft resource limit defines a limit on how much memory the process may lock.
+.P
+Since Linux 2.6.9, no limits are placed on the amount of memory
+that a privileged process can lock and the
+.B RLIMIT_MEMLOCK
+soft resource limit instead defines a limit on how much memory an
+unprivileged process may lock.
+.SH BUGS
+In Linux 4.8 and earlier,
+a bug in the kernel's accounting of locked memory for unprivileged processes
+(i.e., without
+.BR CAP_IPC_LOCK )
+meant that if the region specified by
+.I addr
+and
+.I len
+overlapped an existing lock,
+then the already locked bytes in the overlapping region were counted twice
+when checking against the limit.
+Such double accounting could incorrectly calculate a "total locked memory"
+value for the process that exceeded the
+.B RLIMIT_MEMLOCK
+limit, with the result that
+.BR mlock ()
+and
+.BR mlock2 ()
+would fail on requests that should have succeeded.
+This bug was fixed
+.\" commit 0cf2f6f6dc605e587d2c1120f295934c77e810e8
+in Linux 4.9.
+.P
+In Linux 2.4 series of kernels up to and including Linux 2.4.17,
+a bug caused the
+.BR mlockall ()
+.B MCL_FUTURE
+flag to be inherited across a
+.BR fork (2).
+This was rectified in Linux 2.4.18.
+.P
+Since Linux 2.6.9, if a privileged process calls
+.I mlockall(MCL_FUTURE)
+and later drops privileges (loses the
+.B CAP_IPC_LOCK
+capability by, for example,
+setting its effective UID to a nonzero value),
+then subsequent memory allocations (e.g.,
+.BR mmap (2),
+.BR brk (2))
+will fail if the
+.B RLIMIT_MEMLOCK
+resource limit is encountered.
+.\" See the following LKML thread:
+.\" http://marc.theaimsgroup.com/?l=linux-kernel&m=113801392825023&w=2
+.\" "Rationale for RLIMIT_MEMLOCK"
+.\" 23 Jan 2006
+.SH SEE ALSO
+.BR mincore (2),
+.BR mmap (2),
+.BR setrlimit (2),
+.BR shmctl (2),
+.BR sysconf (3),
+.BR proc (5),
+.BR capabilities (7)
diff --git a/man/man2/mlock2.2 b/man/man2/mlock2.2
new file mode 100644
index 000000000..5e5b3c741
--- /dev/null
+++ b/man/man2/mlock2.2
@@ -0,0 +1 @@
+.so man2/mlock.2
diff --git a/man/man2/mlockall.2 b/man/man2/mlockall.2
new file mode 100644
index 000000000..5e5b3c741
--- /dev/null
+++ b/man/man2/mlockall.2
@@ -0,0 +1 @@
+.so man2/mlock.2
diff --git a/man/man2/mmap.2 b/man/man2/mmap.2
new file mode 100644
index 000000000..63df5a98a
--- /dev/null
+++ b/man/man2/mmap.2
@@ -0,0 +1,1037 @@
+'\" t
+.\" Copyright (C) 1996 Andries Brouwer <aeb@cwi.nl>
+.\" and Copyright (C) 2006, 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2000-03-25 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" Modified 2001-10-04 by John Levon <moz@compsoc.man.ac.uk>
+.\" Modified 2003-02-02 by Andi Kleen <ak@muc.de>
+.\" Modified 2003-05-21 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	MAP_LOCKED works from Linux 2.5.37
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2004-09-11 by aeb
+.\" Modified 2004-12-08, from Eric Estievenart <eric.estievenart@free.fr>
+.\" Modified 2004-12-08, mtk, formatting tidy-ups
+.\" Modified 2006-12-04, mtk, various parts rewritten
+.\" 2007-07-10, mtk, Added an example program.
+.\" 2008-11-18, mtk, document MAP_STACK
+.\"
+.TH mmap 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mmap, munmap \- map or unmap files or devices into memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "void *mmap(void " addr [. length "], size_t " length \
+", int " prot ", int " flags ,
+.BI "           int " fd ", off_t " offset );
+.BI "int munmap(void " addr [. length "], size_t " length );
+.fi
+.P
+See NOTES for information on feature test macro requirements.
+.SH DESCRIPTION
+.BR mmap ()
+creates a new mapping in the virtual address space of
+the calling process.
+The starting address for the new mapping is specified in
+.IR addr .
+The
+.I length
+argument specifies the length of the mapping (which must be greater than 0).
+.P
+If
+.I addr
+is NULL,
+then the kernel chooses the (page-aligned) address
+at which to create the mapping;
+this is the most portable method of creating a new mapping.
+If
+.I addr
+is not NULL,
+then the kernel takes it as a hint about where to place the mapping;
+on Linux, the kernel will pick a nearby page boundary (but always above
+or equal to the value specified by
+.IR /proc/sys/vm/mmap_min_addr )
+and attempt to create the mapping there.
+If another mapping already exists there, the kernel picks a new address that
+may or may not depend on the hint.
+.\" Before Linux 2.6.24, the address was rounded up to the next page
+.\" boundary; since Linux 2.6.24, it is rounded down!
+The address of the new mapping is returned as the result of the call.
+.P
+The contents of a file mapping (as opposed to an anonymous mapping; see
+.B MAP_ANONYMOUS
+below), are initialized using
+.I length
+bytes starting at offset
+.I offset
+in the file (or other object) referred to by the file descriptor
+.IR fd .
+.I offset
+must be a multiple of the page size as returned by
+.IR sysconf(_SC_PAGE_SIZE) .
+.P
+After the
+.BR mmap ()
+call has returned, the file descriptor,
+.IR fd ,
+can be closed immediately without invalidating the mapping.
+.P
+The
+.I prot
+argument describes the desired memory protection of the mapping
+(and must not conflict with the open mode of the file).
+It is either
+.B PROT_NONE
+or the bitwise OR of one or more of the following flags:
+.TP 1.1i
+.B PROT_EXEC
+Pages may be executed.
+.TP
+.B PROT_READ
+Pages may be read.
+.TP
+.B PROT_WRITE
+Pages may be written.
+.TP
+.B PROT_NONE
+Pages may not be accessed.
+.\"
+.SS The flags argument
+The
+.I flags
+argument determines whether updates to the mapping
+are visible to other processes mapping the same region,
+and whether updates are carried through to the underlying file.
+This behavior is determined by including exactly one
+of the following values in
+.IR flags :
+.TP
+.B MAP_SHARED
+Share this mapping.
+Updates to the mapping are visible to other processes mapping the same region,
+and (in the case of file-backed mappings)
+are carried through to the underlying file.
+(To precisely control when updates are carried through
+to the underlying file requires the use of
+.BR msync (2).)
+.TP
+.BR MAP_SHARED_VALIDATE " (since Linux 4.15)"
+This flag provides the same behavior as
+.B MAP_SHARED
+except that
+.B MAP_SHARED
+mappings ignore unknown flags in
+.IR flags .
+By contrast, when creating a mapping using
+.BR MAP_SHARED_VALIDATE ,
+the kernel verifies all passed flags are known and fails the
+mapping with the error
+.B EOPNOTSUPP
+for unknown flags.
+This mapping type is also required to be able to use some mapping flags
+(e.g.,
+.BR MAP_SYNC ).
+.TP
+.B MAP_PRIVATE
+Create a private copy-on-write mapping.
+Updates to the mapping are not visible to other processes
+mapping the same file, and are not carried through to
+the underlying file.
+It is unspecified whether changes made to the file after the
+.BR mmap ()
+call are visible in the mapped region.
+.P
+Both
+.B MAP_SHARED
+and
+.B MAP_PRIVATE
+are described in POSIX.1-2001 and POSIX.1-2008.
+.B MAP_SHARED_VALIDATE
+is a Linux extension.
+.P
+In addition, zero or more of the following values can be ORed in
+.IR flags :
+.TP
+.BR MAP_32BIT " (since Linux 2.4.20, 2.6)"
+Put the mapping into the first 2 Gigabytes of the process address space.
+This flag is supported only on x86-64, for 64-bit programs.
+It was added to allow thread stacks to be allocated somewhere
+in the first 2\ GB of memory,
+so as to improve context-switch performance on some early
+64-bit processors.
+.\" See http://lwn.net/Articles/294642 "Tangled up in threads", 19 Aug 08
+Modern x86-64 processors no longer have this performance problem,
+so use of this flag is not required on those systems.
+The
+.B MAP_32BIT
+flag is ignored when
+.B MAP_FIXED
+is set.
+.TP
+.B MAP_ANON
+Synonym for
+.BR MAP_ANONYMOUS ;
+provided for compatibility with other implementations.
+.TP
+.B MAP_ANONYMOUS
+The mapping is not backed by any file;
+its contents are initialized to zero.
+The
+.I fd
+argument is ignored;
+however, some implementations require
+.I fd
+to be \-1 if
+.B MAP_ANONYMOUS
+(or
+.BR MAP_ANON )
+is specified,
+and portable applications should ensure this.
+The
+.I offset
+argument should be zero.
+.\" See the pgoff overflow check in do_mmap().
+.\" See the offset check in sys_mmap in arch/x86/kernel/sys_x86_64.c.
+Support for
+.B MAP_ANONYMOUS
+in conjunction with
+.B MAP_SHARED
+was added in Linux 2.4.
+.TP
+.B MAP_DENYWRITE
+This flag is ignored.
+.\" Introduced in 1.1.36, removed in 1.3.24.
+(Long ago\[em]Linux 2.0 and earlier\[em]it signaled
+that attempts to write to the underlying file should fail with
+.BR ETXTBSY .
+But this was a source of denial-of-service attacks.)
+.TP
+.B MAP_EXECUTABLE
+This flag is ignored.
+.\" Introduced in 1.1.38, removed in 1.3.24. Flag tested in proc_follow_link.
+.\" (Long ago, it signaled that the underlying file is an executable.
+.\" However, that information was not really used anywhere.)
+.\" Linus talked about DOS related to MAP_EXECUTABLE, but he was thinking of
+.\" MAP_DENYWRITE?
+.TP
+.B MAP_FILE
+Compatibility flag.
+Ignored.
+.\" On some systems, this was required as the opposite of
+.\" MAP_ANONYMOUS -- mtk, 1 May 2007
+.TP
+.B MAP_FIXED
+Don't interpret
+.I addr
+as a hint: place the mapping at exactly that address.
+.I addr
+must be suitably aligned: for most architectures a multiple of the page
+size is sufficient; however, some architectures may impose additional
+restrictions.
+If the memory region specified by
+.I addr
+and
+.I length
+overlaps pages of any existing mapping(s), then the overlapped
+part of the existing mapping(s) will be discarded.
+If the specified address cannot be used,
+.BR mmap ()
+will fail.
+.IP
+Software that aspires to be portable should use the
+.B MAP_FIXED
+flag with care,
+keeping in mind that the exact layout of a process's memory mappings
+is allowed to change significantly between Linux versions,
+C library versions, and operating system releases.
+.I Carefully read the discussion of this flag in NOTES!
+.TP
+.BR MAP_FIXED_NOREPLACE " (since Linux 4.17)"
+.\" commit a4ff8e8620d3f4f50ac4b41e8067b7d395056843
+This flag provides behavior that is similar to
+.B MAP_FIXED
+with respect to the
+.I addr
+enforcement, but differs in that
+.B MAP_FIXED_NOREPLACE
+never clobbers a preexisting mapped range.
+If the requested range would collide with an existing mapping,
+then this call fails with the error
+.B EEXIST.
+This flag can therefore be used as a way to atomically
+(with respect to other threads) attempt to map an address range:
+one thread will succeed; all others will report failure.
+.IP
+Note that older kernels which do not recognize the
+.B MAP_FIXED_NOREPLACE
+flag will typically (upon detecting a collision with a preexisting mapping)
+fall back to a
+.RB \[lq]non- MAP_FIXED \[rq]
+type of behavior:
+they will return an address that is different from the requested address.
+Therefore, backward-compatible software
+should check the returned address against the requested address.
+.TP
+.B MAP_GROWSDOWN
+This flag is used for stacks.
+It indicates to the kernel virtual memory system that the mapping
+should extend downward in memory.
+The return address is one page lower than the memory area that is
+actually created in the process's virtual address space.
+Touching an address in the "guard" page below the mapping will cause
+the mapping to grow by a page.
+This growth can be repeated until the mapping grows to within a
+page of the high end of the next lower mapping,
+at which point touching the "guard" page will result in a
+.B SIGSEGV
+signal.
+.TP
+.BR MAP_HUGETLB " (since Linux 2.6.32)"
+Allocate the mapping using "huge" pages.
+See the Linux kernel source file
+.I Documentation/admin\-guide/mm/hugetlbpage.rst
+for further information, as well as NOTES, below.
+.TP
+.B MAP_HUGE_2MB
+.TQ
+.BR MAP_HUGE_1GB " (since Linux 3.8)"
+.\" See https://lwn.net/Articles/533499/
+Used in conjunction with
+.B MAP_HUGETLB
+to select alternative hugetlb page sizes (respectively, 2\ MB and 1\ GB)
+on systems that support multiple hugetlb page sizes.
+.IP
+More generally, the desired huge page size can be configured by encoding
+the base-2 logarithm of the desired page size in the six bits at the offset
+.BR MAP_HUGE_SHIFT .
+(A value of zero in this bit field provides the default huge page size;
+the default huge page size can be discovered via the
+.I Hugepagesize
+field exposed by
+.IR /proc/meminfo .)
+Thus, the above two constants are defined as:
+.IP
+.in +4n
+.EX
+#define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)
+#define MAP_HUGE_1GB    (30 << MAP_HUGE_SHIFT)
+.EE
+.in
+.IP
+The range of huge page sizes that are supported by the system
+can be discovered by listing the subdirectories in
+.IR /sys/kernel/mm/hugepages .
+.TP
+.BR MAP_LOCKED " (since Linux 2.5.37)"
+Mark the mapped region to be locked in the same way as
+.BR mlock (2).
+This implementation will try to populate (prefault) the whole range but the
+.BR mmap ()
+call doesn't fail with
+.B ENOMEM
+if this fails.
+Therefore major faults might happen later on.
+So the semantic is not as strong as
+.BR mlock (2).
+One should use
+.BR mmap ()
+plus
+.BR mlock (2)
+when major faults are not acceptable after the initialization of the mapping.
+The
+.B MAP_LOCKED
+flag is ignored in older kernels.
+.\" If set, the mapped pages will not be swapped out.
+.TP
+.BR MAP_NONBLOCK " (since Linux 2.5.46)"
+This flag is meaningful only in conjunction with
+.BR MAP_POPULATE .
+Don't perform read-ahead:
+create page tables entries only for pages
+that are already present in RAM.
+Since Linux 2.6.23,
+.\" commit 54cb8821de07f2ffcd28c380ce9b93d5784b40d7
+this flag causes
+.B MAP_POPULATE
+to do nothing.
+One day, the combination of
+.B MAP_POPULATE
+and
+.B MAP_NONBLOCK
+may be reimplemented.
+.TP
+.B MAP_NORESERVE
+Do not reserve swap space for this mapping.
+When swap space is reserved, one has the guarantee
+that it is possible to modify the mapping.
+When swap space is not reserved one might get
+.B SIGSEGV
+upon a write
+if no physical memory is available.
+See also the discussion of the file
+.I /proc/sys/vm/overcommit_memory
+in
+.BR proc (5).
+Before Linux 2.6, this flag had effect only for
+private writable mappings.
+.TP
+.BR MAP_POPULATE " (since Linux 2.5.46)"
+Populate (prefault) page tables for a mapping.
+For a file mapping, this causes read-ahead on the file.
+This will help to reduce blocking on page faults later.
+The
+.BR mmap ()
+call doesn't fail if the mapping cannot be populated (for example, due
+to limitations on the number of mapped huge pages when using
+.BR MAP_HUGETLB ).
+Support for
+.B MAP_POPULATE
+in conjunction with private mappings was added in Linux 2.6.23.
+.TP
+.BR MAP_STACK " (since Linux 2.6.27)"
+Allocate the mapping at an address suitable for a process
+or thread stack.
+.IP
+This flag is currently a no-op on Linux.
+However, by employing this flag, applications can ensure that
+they transparently obtain support if the flag
+is implemented in the future.
+Thus, it is used in the glibc threading implementation to allow for
+the fact that some architectures may (later) require special treatment
+for stack allocations.
+.\" See http://lwn.net/Articles/294642 "Tangled up in threads", 19 Aug 08
+.\" commit cd98a04a59e2f94fa64d5bf1e26498d27427d5e7
+.\" http://thread.gmane.org/gmane.linux.kernel/720412
+.\" "pthread_create() slow for many threads; also time to revisit 64b
+.\"  context switch optimization?"
+A further reason to employ this flag is portability:
+.B MAP_STACK
+exists (and has an effect) on some other systems (e.g., some of the BSDs).
+.TP
+.BR MAP_SYNC " (since Linux 4.15)"
+This flag is available only with the
+.B MAP_SHARED_VALIDATE
+mapping type;
+mappings of type
+.B MAP_SHARED
+will silently ignore this flag.
+This flag is supported only for files supporting DAX
+(direct mapping of persistent memory).
+For other files, creating a mapping with this flag results in an
+.B EOPNOTSUPP
+error.
+.IP
+Shared file mappings with this flag provide the guarantee that while
+some memory is mapped writable in the address space of the process,
+it will be visible in the same file at the same offset even after
+the system crashes or is rebooted.
+In conjunction with the use of appropriate CPU instructions,
+this provides users of such mappings with a more efficient way
+of making data modifications persistent.
+.TP
+.BR MAP_UNINITIALIZED " (since Linux 2.6.33)"
+Don't clear anonymous pages.
+This flag is intended to improve performance on embedded devices.
+This flag is honored only if the kernel was configured with the
+.B CONFIG_MMAP_ALLOW_UNINITIALIZED
+option.
+Because of the security implications,
+that option is normally enabled only on embedded devices
+(i.e., devices where one has complete control of the contents of user memory).
+.P
+Of the above flags, only
+.B MAP_FIXED
+is specified in POSIX.1-2001 and POSIX.1-2008.
+However, most systems also support
+.B MAP_ANONYMOUS
+(or its synonym
+.BR MAP_ANON ).
+.\" FIXME . for later review when Issue 8 is one day released...
+.\" POSIX may add MAP_ANON in the future
+.\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
+.\" http://austingroupbugs.net/view.php?id=850
+.SS munmap()
+The
+.BR munmap ()
+system call deletes the mappings for the specified address range, and
+causes further references to addresses within the range to generate
+invalid memory references.
+The region is also automatically unmapped
+when the process is terminated.
+On the other hand, closing the file
+descriptor does not unmap the region.
+.P
+The address
+.I addr
+must be a multiple of the page size (but
+.I length
+need not be).
+All pages containing a part
+of the indicated range are unmapped, and subsequent references
+to these pages will generate
+.BR SIGSEGV .
+It is not an error if the
+indicated range does not contain any mapped pages.
+.SH RETURN VALUE
+On success,
+.BR mmap ()
+returns a pointer to the mapped area.
+On error, the value
+.B MAP_FAILED
+(that is,
+.IR "(void\ *)\ \-1" )
+is returned, and
+.I errno
+is set to indicate the error.
+.P
+On success,
+.BR munmap ()
+returns 0.
+On failure, it returns \-1, and
+.I errno
+is set to indicate the error (probably to
+.BR EINVAL ).
+.SH ERRORS
+.TP
+.B EACCES
+A file descriptor refers to a non-regular file.
+Or a file mapping was requested, but
+.I fd
+is not open for reading.
+Or
+.B MAP_SHARED
+was requested and
+.B PROT_WRITE
+is set, but
+.I fd
+is not open in read/write
+.RB ( O_RDWR )
+mode.
+Or
+.B PROT_WRITE
+is set, but the file is append-only.
+.TP
+.B EAGAIN
+The file has been locked, or too much memory has been locked (see
+.BR setrlimit (2)).
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor (and
+.B MAP_ANONYMOUS
+was not set).
+.TP
+.B EEXIST
+.B MAP_FIXED_NOREPLACE
+was specified in
+.IR flags ,
+and the range covered by
+.I addr
+and
+.I length
+clashes with an existing mapping.
+.TP
+.B EINVAL
+We don't like
+.IR addr ,
+.IR length ,
+or
+.I offset
+(e.g., they are too large, or not aligned on a page boundary).
+.TP
+.B EINVAL
+(since Linux 2.6.12)
+.I length
+was 0.
+.TP
+.B EINVAL
+.I flags
+contained none of
+.BR MAP_PRIVATE ,
+.BR MAP_SHARED ,
+or
+.BR MAP_SHARED_VALIDATE .
+.TP
+.B ENFILE
+.\" This is for shared anonymous segments
+.\" [2.6.7] shmem_zero_setup()-->shmem_file_setup()-->get_empty_filp()
+The system-wide limit on the total number of open files has been reached.
+.\" .TP
+.\" .B ENOEXEC
+.\" A file could not be mapped for reading.
+.TP
+.B ENODEV
+The underlying filesystem of the specified file does not support
+memory mapping.
+.TP
+.B ENOMEM
+No memory is available.
+.TP
+.B ENOMEM
+The process's maximum number of mappings would have been exceeded.
+This error can also occur for
+.BR munmap (),
+when unmapping a region in the middle of an existing mapping,
+since this results in two smaller mappings on either side of
+the region being unmapped.
+.TP
+.B ENOMEM
+(since Linux 4.7)
+The process's
+.B RLIMIT_DATA
+limit, described in
+.BR getrlimit (2),
+would have been exceeded.
+.TP
+.B ENOMEM
+We don't like
+.IR addr ,
+because it exceeds the virtual address space of the CPU.
+.TP
+.B EOVERFLOW
+On 32-bit architecture together with the large file extension
+(i.e., using 64-bit
+.IR off_t ):
+the number of pages used for
+.I length
+plus number of pages used for
+.I offset
+would overflow
+.I "unsigned long"
+(32 bits).
+.TP
+.B EPERM
+The
+.I prot
+argument asks for
+.B PROT_EXEC
+but the mapped area belongs to a file on a filesystem that
+was mounted no-exec.
+.\" (Since Linux 2.4.25 / Linux 2.6.0.)
+.TP
+.B EPERM
+The operation was prevented by a file seal; see
+.BR fcntl (2).
+.TP
+.B EPERM
+The
+.B MAP_HUGETLB
+flag was specified, but the caller was not privileged (did not have the
+.B CAP_IPC_LOCK
+capability)
+and is not a member of the
+.I sysctl_hugetlb_shm_group
+group; see the description of
+.I /proc/sys/vm/sysctl_hugetlb_shm_group
+in
+.BR proc_sys (5).
+.TP
+.B ETXTBSY
+.B MAP_DENYWRITE
+was set but the object specified by
+.I fd
+is open for writing.
+.P
+Use of a mapped region can result in these signals:
+.TP
+.B SIGSEGV
+Attempted write into a region mapped as read-only.
+.TP
+.B SIGBUS
+Attempted access to a page of the buffer that lies beyond the
+end of the mapped file.
+For an explanation of the treatment of the bytes in the page that
+corresponds to the end of a mapped file that is not a multiple
+of the page size, see NOTES.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mmap (),
+.BR munmap ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On some hardware architectures (e.g., i386),
+.B PROT_WRITE
+implies
+.BR PROT_READ .
+It is architecture dependent whether
+.B PROT_READ
+implies
+.B PROT_EXEC
+or not.
+Portable programs should always set
+.B PROT_EXEC
+if they intend to execute code in the new mapping.
+.P
+The portable way to create a mapping is to specify
+.I addr
+as 0 (NULL), and omit
+.B MAP_FIXED
+from
+.IR flags .
+In this case, the system chooses the address for the mapping;
+the address is chosen so as not to conflict with any existing mapping,
+and will not be 0.
+If the
+.B MAP_FIXED
+flag is specified, and
+.I addr
+is 0 (NULL), then the mapped address will be 0 (NULL).
+.P
+Certain
+.I flags
+constants are defined only if suitable feature test macros are defined
+(possibly by default):
+.B _DEFAULT_SOURCE
+with glibc 2.19 or later;
+or
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+in glibc 2.19 and earlier.
+(Employing
+.B _GNU_SOURCE
+also suffices,
+and requiring that macro specifically would have been more logical,
+since these flags are all Linux-specific.)
+The relevant flags are:
+.BR MAP_32BIT ,
+.B MAP_ANONYMOUS
+(and the synonym
+.BR MAP_ANON ),
+.BR MAP_DENYWRITE ,
+.BR MAP_EXECUTABLE ,
+.BR MAP_FILE ,
+.BR MAP_GROWSDOWN ,
+.BR MAP_HUGETLB ,
+.BR MAP_LOCKED ,
+.BR MAP_NONBLOCK ,
+.BR MAP_NORESERVE ,
+.BR MAP_POPULATE ,
+and
+.BR MAP_STACK .
+.SS C library/kernel differences
+This page describes the interface provided by the glibc
+.BR mmap ()
+wrapper function.
+Originally, this function invoked a system call of the same name.
+Since Linux 2.4, that system call has been superseded by
+.BR mmap2 (2),
+and nowadays
+.\" Since around glibc 2.1/2.2, depending on the platform.
+the glibc
+.BR mmap ()
+wrapper function invokes
+.BR mmap2 (2)
+with a suitably adjusted value for
+.IR offset .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD.
+.\" SVr4 documents additional error codes ENXIO and ENODEV.
+.\" SUSv2 documents additional error codes EMFILE and EOVERFLOW.
+.P
+On POSIX systems on which
+.BR mmap (),
+.BR msync (2),
+and
+.BR munmap ()
+are available,
+.B _POSIX_MAPPED_FILES
+is defined in \fI<unistd.h>\fP to a value greater than 0.
+(See also
+.BR sysconf (3).)
+.\" POSIX.1-2001: It shall be defined to -1 or 0 or 200112L.
+.\" -1: unavailable, 0: ask using sysconf().
+.\" glibc defines it to 1.
+.SH NOTES
+Memory mapped by
+.BR mmap ()
+is preserved across
+.BR fork (2),
+with the same attributes.
+.P
+A file is mapped in multiples of the page size.
+For a file that is not
+a multiple of the page size,
+the remaining bytes in the partial page at the end of the mapping
+are zeroed when mapped,
+and modifications to that region are not written out to the file.
+The effect of
+changing the size of the underlying file of a mapping on the pages that
+correspond to added or removed regions of the file is unspecified.
+.P
+An application can determine which pages of a mapping are
+currently resident in the buffer/page cache using
+.BR mincore (2).
+.\"
+.SS Using MAP_FIXED safely
+The only safe use for
+.B MAP_FIXED
+is where the address range specified by
+.I addr
+and
+.I length
+was previously reserved using another mapping;
+otherwise, the use of
+.B MAP_FIXED
+is hazardous because it forcibly removes preexisting mappings,
+making it easy for a multithreaded process to corrupt its own address space.
+.P
+For example, suppose that thread A looks through
+.IR /proc/ pid /maps
+in order to locate an unused address range that it can map using
+.BR MAP_FIXED ,
+while thread B simultaneously acquires part or all of that same
+address range.
+When thread A subsequently employs
+.BR mmap(MAP_FIXED) ,
+it will effectively clobber the mapping that thread B created.
+In this scenario,
+thread B need not create a mapping directly; simply making a library call
+that, internally, uses
+.BR dlopen (3)
+to load some other shared library, will suffice.
+The
+.BR dlopen (3)
+call will map the library into the process's address space.
+Furthermore, almost any library call may be implemented in a way that
+adds memory mappings to the address space, either with this technique,
+or by simply allocating memory.
+Examples include
+.BR brk (2),
+.BR malloc (3),
+.BR pthread_create (3),
+and the PAM libraries
+.UR http://www.linux-pam.org
+.UE .
+.P
+Since Linux 4.17, a multithreaded program can use the
+.B MAP_FIXED_NOREPLACE
+flag to avoid the hazard described above
+when attempting to create a mapping at a fixed address
+that has not been reserved by a preexisting mapping.
+.\"
+.SS Timestamps changes for file-backed mappings
+For file-backed mappings, the
+.I st_atime
+field for the mapped file may be updated at any time between the
+.BR mmap ()
+and the corresponding unmapping; the first reference to a mapped
+page will update the field if it has not been already.
+.P
+The
+.I st_ctime
+and
+.I st_mtime
+field for a file mapped with
+.B PROT_WRITE
+and
+.B MAP_SHARED
+will be updated after
+a write to the mapped region, and before a subsequent
+.BR msync (2)
+with the
+.B MS_SYNC
+or
+.B MS_ASYNC
+flag, if one occurs.
+.\"
+.SS Huge page (Huge TLB) mappings
+For mappings that employ huge pages, the requirements for the arguments of
+.BR mmap ()
+and
+.BR munmap ()
+differ somewhat from the requirements for mappings
+that use the native system page size.
+.P
+For
+.BR mmap (),
+.I offset
+must be a multiple of the underlying huge page size.
+The system automatically aligns
+.I length
+to be a multiple of the underlying huge page size.
+.P
+For
+.BR munmap (),
+.IR addr ,
+and
+.I length
+must both be a multiple of the underlying huge page size.
+.\"
+.SH BUGS
+On Linux, there are no guarantees like those suggested above under
+.BR MAP_NORESERVE .
+By default, any process can be killed
+at any moment when the system runs out of memory.
+.P
+Before Linux 2.6.7, the
+.B MAP_POPULATE
+flag has effect only if
+.I prot
+is specified as
+.BR PROT_NONE .
+.P
+SUSv3 specifies that
+.BR mmap ()
+should fail if
+.I length
+is 0.
+However, before Linux 2.6.12,
+.BR mmap ()
+succeeded in this case: no mapping was created and the call returned
+.IR addr .
+Since Linux 2.6.12,
+.BR mmap ()
+fails with the error
+.B EINVAL
+for this case.
+.P
+POSIX specifies that the system shall always
+zero fill any partial page at the end
+of the object and that system will never write any modification of the
+object beyond its end.
+On Linux, when you write data to such partial page after the end
+of the object, the data stays in the page cache even after the file
+is closed and unmapped
+and even though the data is never written to the file itself,
+subsequent mappings may see the modified content.
+In some cases, this could be fixed by calling
+.BR msync (2)
+before the unmap takes place;
+however, this doesn't work on
+.BR tmpfs (5)
+(for example, when using the POSIX shared memory interface documented in
+.BR shm_overview (7)).
+.SH EXAMPLES
+.\" FIXME . Add an example here that uses an anonymous shared region for
+.\" IPC between parent and child.
+The following program prints part of the file specified in
+its first command-line argument to standard output.
+The range of bytes to be printed is specified via offset and length
+values in the second and third command-line arguments.
+The program creates a memory mapping of the required
+pages of the file and then uses
+.BR write (2)
+to output the desired bytes.
+.SS Program source
+.\" SRC BEGIN (mmap.c)
+.EX
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+\&
+#define handle_error(msg) \e
+    do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+int
+main(int argc, char *argv[])
+{
+    int          fd;
+    char         *addr;
+    off_t        offset, pa_offset;
+    size_t       length;
+    ssize_t      s;
+    struct stat  sb;
+\&
+    if (argc < 3 || argc > 4) {
+        fprintf(stderr, "%s file offset [length]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fd = open(argv[1], O_RDONLY);
+    if (fd == \-1)
+        handle_error("open");
+\&
+    if (fstat(fd, &sb) == \-1)           /* To obtain file size */
+        handle_error("fstat");
+\&
+    offset = atoi(argv[2]);
+    pa_offset = offset & \[ti](sysconf(_SC_PAGE_SIZE) \- 1);
+        /* offset for mmap() must be page aligned */
+\&
+    if (offset >= sb.st_size) {
+        fprintf(stderr, "offset is past end of file\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (argc == 4) {
+        length = atoi(argv[3]);
+        if (offset + length > sb.st_size)
+            length = sb.st_size \- offset;
+                /* Can\[aq]t display bytes past end of file */
+\&
+    } else {    /* No length arg ==> display to end of file */
+        length = sb.st_size \- offset;
+    }
+\&
+    addr = mmap(NULL, length + offset \- pa_offset, PROT_READ,
+                MAP_PRIVATE, fd, pa_offset);
+    if (addr == MAP_FAILED)
+        handle_error("mmap");
+\&
+    s = write(STDOUT_FILENO, addr + offset \- pa_offset, length);
+    if (s != length) {
+        if (s == \-1)
+            handle_error("write");
+\&
+        fprintf(stderr, "partial write");
+        exit(EXIT_FAILURE);
+    }
+\&
+    munmap(addr, length + offset \- pa_offset);
+    close(fd);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ftruncate (2),
+.BR getpagesize (2),
+.BR memfd_create (2),
+.BR mincore (2),
+.BR mlock (2),
+.BR mmap2 (2),
+.BR mprotect (2),
+.BR mremap (2),
+.BR msync (2),
+.BR remap_file_pages (2),
+.BR setrlimit (2),
+.BR shmat (2),
+.BR userfaultfd (2),
+.BR shm_open (3),
+.BR shm_overview (7)
+.P
+The descriptions of the following files in
+.BR proc (5):
+.IR /proc/ pid /maps ,
+.IR /proc/ pid /map_files ,
+and
+.IR /proc/ pid /smaps .
+.P
+B.O. Gallmeister, POSIX.4, O'Reilly, pp. 128\[en]129 and 389\[en]391.
+.\"
+.\" Repeat after me: private read-only mappings are 100% equivalent to
+.\" shared read-only mappings. No ifs, buts, or maybes. -- Linus
diff --git a/man/man2/mmap2.2 b/man/man2/mmap2.2
new file mode 100644
index 000000000..594a207ec
--- /dev/null
+++ b/man/man2/mmap2.2
@@ -0,0 +1,85 @@
+.\" Copyright (C) 2002, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 31 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added description of mmap2
+.\" Modified, 2004-11-25, mtk -- removed stray #endif in prototype
+.\"
+.TH mmap2 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mmap2 \- map files or devices into memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/mman.h>" "    /* Definition of " MAP_* " and " PROT_* " constants */"
+.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "void *syscall(SYS_mmap2, unsigned long " addr ", unsigned long " length ,
+.BI "              unsigned long " prot ", unsigned long " flags ,
+.BI "              unsigned long " fd ", unsigned long " pgoffset );
+.fi
+.SH DESCRIPTION
+This is probably not the system call that you are interested in; instead, see
+.BR mmap (2),
+which describes the glibc wrapper function that invokes this system call.
+.P
+The
+.BR mmap2 ()
+system call provides the same interface as
+.BR mmap (2),
+except that the final argument specifies the offset into the
+file in 4096-byte units (instead of bytes, as is done by
+.BR mmap (2)).
+This enables applications that use a 32-bit
+.I off_t
+to map large files (up to 2\[ha]44 bytes).
+.SH RETURN VALUE
+On success,
+.BR mmap2 ()
+returns a pointer to the mapped area.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Problem with getting the data from user space.
+.TP
+.B EINVAL
+(Various platforms where the page size is not 4096 bytes.)
+.I "offset\ *\ 4096"
+is not a multiple of the system page size.
+.P
+.BR mmap2 ()
+can also return any of the errors described in
+.BR mmap (2).
+.SH VERSIONS
+On architectures where this system call is present,
+the glibc
+.BR mmap ()
+wrapper function invokes this system call rather than the
+.BR mmap (2)
+system call.
+.P
+This system call does not exist on x86-64.
+.P
+On ia64, the unit for
+.I offset
+is actually the system page size, rather than 4096 bytes.
+.\" ia64 can have page sizes ranging from 4 kB to 64 kB.
+.\" On cris, it looks like the unit might also be the page size,
+.\" which is 8192 bytes. -- mtk, June 2007
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.3.31.
+.SH SEE ALSO
+.BR getpagesize (2),
+.BR mmap (2),
+.BR mremap (2),
+.BR msync (2),
+.BR shm_open (3)
diff --git a/man/man2/modify_ldt.2 b/man/man2/modify_ldt.2
new file mode 100644
index 000000000..7af91ed59
--- /dev/null
+++ b/man/man2/modify_ldt.2
@@ -0,0 +1,196 @@
+.\" Copyright (c) 1995 Michael Chastain (mec@duracef.shout.net), 22 July 1995.
+.\" Copyright (c) 2015 Andrew Lutomirski
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH modify_ldt 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+modify_ldt \- get or set a per-process LDT entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <asm/ldt.h>" "         /* Definition of " "struct user_desc" " */"
+.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_modify_ldt, int " func ", void " ptr [. bytecount ],
+.BI "            unsigned long " bytecount );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR modify_ldt (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR modify_ldt ()
+reads or writes the local descriptor table (LDT) for a process.
+The LDT
+is an array of segment descriptors that can be referenced by user code.
+Linux allows processes to configure a per-process (actually per-mm) LDT.
+For more information about the LDT, see the Intel Software Developer's
+Manual or the AMD Architecture Programming Manual.
+.P
+When
+.I func
+is 0,
+.BR modify_ldt ()
+reads the LDT into the memory pointed to by
+.IR ptr .
+The number of bytes read is the smaller of
+.I bytecount
+and the actual size of the LDT, although the kernel may act as though
+the LDT is padded with additional trailing zero bytes.
+On success,
+.BR modify_ldt ()
+will return the number of bytes read.
+.P
+When
+.I func
+is 1 or 0x11,
+.BR modify_ldt ()
+modifies the LDT entry indicated by
+.IR ptr\->entry_number .
+.I ptr
+points to a
+.I user_desc
+structure
+and
+.I bytecount
+must equal the size of this structure.
+.P
+The
+.I user_desc
+structure is defined in \fI<asm/ldt.h>\fP as:
+.P
+.in +4n
+.EX
+struct user_desc {
+    unsigned int  entry_number;
+    unsigned int  base_addr;
+    unsigned int  limit;
+    unsigned int  seg_32bit:1;
+    unsigned int  contents:2;
+    unsigned int  read_exec_only:1;
+    unsigned int  limit_in_pages:1;
+    unsigned int  seg_not_present:1;
+    unsigned int  useable:1;
+};
+.EE
+.in
+.P
+In Linux 2.4 and earlier, this structure was named
+.IR modify_ldt_ldt_s .
+.P
+The
+.I contents
+field is the segment type (data, expand-down data, non-conforming code, or
+conforming code).
+The other fields match their descriptions in the CPU manual, although
+.BR modify_ldt ()
+cannot set the hardware-defined "accessed" bit described in the CPU manual.
+.P
+A
+.I user_desc
+is considered "empty" if
+.I read_exec_only
+and
+.I seg_not_present
+are set to 1 and all of the other fields are 0.
+An LDT entry can be cleared by setting it to an "empty"
+.I user_desc
+or, if
+.I func
+is 1, by setting both
+.I base
+and
+.I limit
+to 0.
+.P
+A conforming code segment (i.e., one with
+.IR contents==3 )
+will be rejected if
+.I
+func
+is 1 or if
+.I seg_not_present
+is 0.
+.P
+When
+.I func
+is 2,
+.BR modify_ldt ()
+will read zeros.
+This appears to be a leftover from Linux 2.4.
+.SH RETURN VALUE
+On success,
+.BR modify_ldt ()
+returns either the actual number of bytes read (for reading)
+or 0 (for writing).
+On failure,
+.BR modify_ldt ()
+returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I ptr
+points outside the address space.
+.TP
+.B EINVAL
+.I ptr
+is 0,
+or
+.I func
+is 1 and
+.I bytecount
+is not equal to the size of the structure
+.IR user_desc ,
+or
+.I func
+is 1 or 0x11 and the new LDT entry has invalid values.
+.TP
+.B ENOSYS
+.I func
+is neither 0, 1, 2, nor 0x11.
+.SH STANDARDS
+Linux.
+.SH NOTES
+.BR modify_ldt ()
+should not be used for thread-local storage, as it slows down context
+switches and only supports a limited number of threads.
+Threading libraries should use
+.BR set_thread_area (2)
+or
+.BR arch_prctl (2)
+instead, except on extremely old kernels that do not support those system
+calls.
+.P
+The normal use for
+.BR modify_ldt ()
+is to run legacy 16-bit or segmented 32-bit code.
+Not all kernels allow 16-bit segments to be installed, however.
+.P
+Even on 64-bit kernels,
+.BR modify_ldt ()
+cannot be used to create a long mode (i.e., 64-bit) code segment.
+The undocumented field "lm" in
+.I user_desc
+is not useful, and, despite its name,
+does not result in a long mode segment.
+.SH BUGS
+On 64-bit kernels before Linux 3.19,
+.\" commit e30ab185c490e9a9381385529e0fd32f0a399495
+setting the "lm" bit in
+.I user_desc
+prevents the descriptor from being considered empty.
+Keep in mind that the
+"lm" bit does not exist in the 32-bit headers, but these buggy kernels
+will still notice the bit even when set in a 32-bit process.
+.SH SEE ALSO
+.BR arch_prctl (2),
+.BR set_thread_area (2),
+.BR vm86 (2)
diff --git a/man/man2/mount.2 b/man/man2/mount.2
new file mode 100644
index 000000000..d8a691e13
--- /dev/null
+++ b/man/man2/mount.2
@@ -0,0 +1,971 @@
+.\" Copyright (C) 1993 Rickard E. Faith <faith@cs.unc.edu>
+.\" and Copyright (C) 1994 Andries E. Brouwer <aeb@cwi.nl>
+.\" and Copyright (C) 2002, 2005, 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1996-11-04 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-10-13 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added note on historical behavior of MS_NOSUID
+.\" Modified 2002-05-16 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Extensive changes and additions
+.\" Modified 2002-05-27 by aeb
+.\" Modified 2002-06-11 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Enhanced descriptions of MS_MOVE, MS_BIND, and MS_REMOUNT
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2005-05-18, mtk, Added MNT_EXPIRE, plus a few other tidy-ups.
+.\" 2008-10-06, mtk: move umount*() material into separate umount.2 page.
+.\" 2008-10-06, mtk: Add discussion of namespaces.
+.\"
+.TH mount 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mount \- mount filesystem
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <sys/mount.h>"
+.P
+.BI "int mount(const char *" source ", const char *" target ,
+.BI "          const char *" filesystemtype ", unsigned long " mountflags ,
+.BI "          const void *_Nullable " data );
+.fi
+.SH DESCRIPTION
+.BR mount ()
+attaches the filesystem specified by
+.I source
+(which is often a pathname referring to a device,
+but can also be the pathname of a directory or file,
+or a dummy string) to the location (a directory or file)
+specified by the pathname in
+.IR target .
+.P
+Appropriate privilege (Linux: the
+.B CAP_SYS_ADMIN
+capability) is required to mount filesystems.
+.P
+Values for the
+.I filesystemtype
+argument supported by the kernel are listed in
+.I /proc/filesystems
+(e.g., "btrfs", "ext4", "jfs", "xfs", "vfat", "fuse",
+"tmpfs", "cgroup", "proc", "mqueue", "nfs", "cifs", "iso9660").
+Further types may become available when the appropriate modules
+are loaded.
+.P
+The
+.I data
+argument is interpreted by the different filesystems.
+Typically it is a string of comma-separated options
+understood by this filesystem.
+See
+.BR mount (8)
+for details of the options available for each filesystem type.
+This argument may be specified as NULL, if there are no options.
+.P
+A call to
+.BR mount ()
+performs one of a number of general types of operation,
+depending on the bits specified in
+.IR mountflags .
+The choice of which operation to perform is determined by
+testing the bits set in
+.IR mountflags ,
+with the tests being conducted in the order listed here:
+.IP \[bu] 3
+Remount an existing mount:
+.I mountflags
+includes
+.BR MS_REMOUNT .
+.IP \[bu]
+Create a bind mount:
+.I mountflags
+includes
+.BR MS_BIND .
+.IP \[bu]
+Change the propagation type of an existing mount:
+.I mountflags
+includes one of
+.BR MS_SHARED ,
+.BR MS_PRIVATE ,
+.BR MS_SLAVE ,
+or
+.BR MS_UNBINDABLE .
+.IP \[bu]
+Move an existing mount to a new location:
+.I mountflags
+includes
+.BR MS_MOVE .
+.IP \[bu]
+Create a new mount:
+.I mountflags
+includes none of the above flags.
+.P
+Each of these operations is detailed later in this page.
+Further flags may be specified in
+.I mountflags
+to modify the behavior of
+.BR mount (),
+as described below.
+.\"
+.SS Additional mount flags
+The list below describes the additional flags that can be specified in
+.IR mountflags .
+Note that some operation types ignore some or all of these flags,
+as described later in this page.
+.\"
+.\" FIXME 2.6.25 Added MS_I_VERSION, which needs to be documented.
+.\" commit 7a224228ed79d587ece2304869000aad1b8e97dd
+.\" (This is a per-superblock flag)
+.\"
+.TP
+.BR MS_DIRSYNC " (since Linux 2.5.19)"
+Make directory changes on this filesystem synchronous.
+(This property can be obtained for individual directories
+or subtrees using
+.BR chattr (1).)
+.TP
+.BR MS_LAZYTIME " (since Linux 4.0)"
+.\" commit 0ae45f63d4ef8d8eeec49c7d8b44a1775fff13e8
+.\" commit fe032c422c5ba562ba9c2d316f55e258e03259c6
+.\" commit a26f49926da938f47561f386be56a83dd37a496d
+Reduce on-disk updates of inode timestamps (atime, mtime, ctime)
+by maintaining these changes only in memory.
+The on-disk timestamps are updated only when:
+.RS
+.IP \[bu] 3
+the inode needs to be updated for some change unrelated to file timestamps;
+.IP \[bu]
+the application employs
+.BR fsync (2),
+.BR syncfs (2),
+or
+.BR sync (2);
+.IP \[bu]
+an undeleted inode is evicted from memory; or
+.IP \[bu]
+more than 24 hours have passed since the inode was written to disk.
+.RE
+.IP
+This mount option significantly reduces writes
+needed to update the inode's timestamps, especially mtime and atime.
+However, in the event of a system crash, the atime and mtime fields
+on disk might be out of date by up to 24 hours.
+.IP
+Examples of workloads where this option could be of significant benefit
+include frequent random writes to preallocated files,
+as well as cases where the
+.B MS_STRICTATIME
+mount option is also enabled.
+(The advantage of combining
+.B MS_STRICTATIME
+and
+.B MS_LAZYTIME
+is that
+.BR stat (2)
+will return the correctly updated atime, but the atime updates
+will be flushed to disk only in the cases listed above.)
+.TP
+.B MS_MANDLOCK
+Permit mandatory locking on files in this filesystem.
+(Mandatory locking must still be enabled on a per-file basis,
+as described in
+.BR fcntl (2).)
+Since Linux 4.5,
+.\" commit 95ace75414f312f9a7b93d873f386987b92a5301
+this mount option requires the
+.B CAP_SYS_ADMIN
+capability and a kernel configured with the
+.B CONFIG_MANDATORY_FILE_LOCKING
+option.
+Mandatory locking has been fully deprecated in Linux 5.15, so
+this flag should be considered deprecated.
+.TP
+.B MS_NOATIME
+Do not update access times for (all types of) files on this filesystem.
+.TP
+.B MS_NODEV
+Do not allow access to devices (special files) on this filesystem.
+.TP
+.B MS_NODIRATIME
+Do not update access times for directories on this filesystem.
+This flag provides a subset of the functionality provided by
+.BR MS_NOATIME ;
+that is,
+.B MS_NOATIME
+implies
+.BR MS_NODIRATIME .
+.TP
+.B MS_NOEXEC
+Do not allow programs to be executed from this filesystem.
+.\" (Possibly useful for a filesystem that contains non-Linux executables.
+.\" Often used as a security feature, e.g., to make sure that restricted
+.\" users cannot execute files uploaded using ftp or so.)
+.TP
+.B MS_NOSUID
+Do not honor set-user-ID and set-group-ID bits or file capabilities
+when executing programs from this filesystem.
+In addition, SELinux domain
+transitions require the permission
+.IR nosuid_transition ,
+which in turn needs
+also the policy capability
+.IR nnp_nosuid_transition .
+.\" (This is a security feature to prevent users executing set-user-ID and
+.\" set-group-ID programs from removable disk devices.)
+.TP
+.B MS_RDONLY
+Mount filesystem read-only.
+.TP
+.BR MS_REC " (since Linux 2.4.11)"
+Used in conjunction with
+.B MS_BIND
+to create a recursive bind mount,
+and in conjunction with the propagation type flags to recursively change
+the propagation type of all of the mounts in a subtree.
+See below for further details.
+.TP
+.BR MS_RELATIME " (since Linux 2.6.20)"
+When a file on this filesystem is accessed,
+update the file's last access time (atime) only if the current value
+of atime is less than or equal to the file's last modification time (mtime)
+or last status change time (ctime).
+This option is useful for programs, such as
+.BR mutt (1),
+that need to know when a file has been read since it was last modified.
+Since Linux 2.6.30, the kernel defaults to the behavior provided
+by this flag (unless
+.B MS_NOATIME
+was specified), and the
+.B MS_STRICTATIME
+flag is required to obtain traditional semantics.
+In addition, since Linux 2.6.30,
+the file's last access time is always updated if it
+is more than 1 day old.
+.\" Matthew Garrett notes in the patch that added this behavior
+.\" that this lets utilities such as tmpreaper (which deletes
+.\" files based on last access time) work correctly.
+.TP
+.BR MS_SILENT " (since Linux 2.6.17)"
+Suppress the display of certain
+.RI ( printk ())
+warning messages in the kernel log.
+This flag supersedes the misnamed and obsolete
+.B MS_VERBOSE
+flag (available since Linux 2.4.12), which has the same meaning.
+.TP
+.BR MS_STRICTATIME " (since Linux 2.6.30)"
+Always update the last access time (atime) when files on this
+filesystem are accessed.
+(This was the default behavior before Linux 2.6.30.)
+Specifying this flag overrides the effect of setting the
+.B MS_NOATIME
+and
+.B MS_RELATIME
+flags.
+.TP
+.B MS_SYNCHRONOUS
+Make writes on this filesystem synchronous (as though
+the
+.B O_SYNC
+flag to
+.BR open (2)
+was specified for all file opens to this filesystem).
+.TP
+.BR MS_NOSYMFOLLOW " (since Linux 5.10)"
+.\" dab741e0e02bd3c4f5e2e97be74b39df2523fc6e
+Do not follow symbolic links when resolving paths.
+Symbolic links can still be created,
+and
+.BR readlink (1),
+.BR readlink (2),
+.BR realpath (1),
+and
+.BR realpath (3)
+all still work properly.
+.P
+From Linux 2.4 onward, some of the above flags are
+settable on a per-mount basis,
+while others apply to the superblock of the mounted filesystem,
+meaning that all mounts of the same filesystem share those flags.
+(Previously, all of the flags were per-superblock.)
+.P
+The per-mount-point flags are as follows:
+.IP \[bu] 3
+Since Linux 2.4:
+.BR MS_NODEV ", " MS_NOEXEC ", and " MS_NOSUID
+flags are settable on a per-mount-point basis.
+.IP \[bu]
+Additionally, since Linux 2.6.16:
+.B MS_NOATIME
+and
+.BR MS_NODIRATIME .
+.IP \[bu]
+Additionally, since Linux 2.6.20:
+.BR MS_RELATIME .
+.P
+The following flags are per-superblock:
+.BR MS_DIRSYNC ,
+.BR MS_LAZYTIME ,
+.BR MS_MANDLOCK ,
+.BR MS_SILENT ,
+and
+.BR MS_SYNCHRONOUS .
+.\" And MS_I_VERSION?
+The initial settings of these flags are determined on the first
+mount of the filesystem, and will be shared by all subsequent mounts
+of the same filesystem.
+Subsequently, the settings of the flags can be changed
+via a remount operation (see below).
+Such changes will be visible via all mounts associated
+with the filesystem.
+.P
+Since Linux 2.6.16,
+.B MS_RDONLY
+can be set or cleared on a per-mount-point basis as well as on
+the underlying filesystem superblock.
+The mounted filesystem will be writable only if neither the filesystem
+nor the mountpoint are flagged as read-only.
+.\"
+.SS Remounting an existing mount
+An existing mount may be remounted by specifying
+.B MS_REMOUNT
+in
+.IR mountflags .
+This allows you to change the
+.I mountflags
+and
+.I data
+of an existing mount without having to unmount and remount the filesystem.
+.I target
+should be the same value specified in the initial
+.BR mount ()
+call.
+.P
+The
+.I source
+and
+.I filesystemtype
+arguments are ignored.
+.P
+The
+.I mountflags
+and
+.I data
+arguments should match the values used in the original
+.BR mount ()
+call, except for those parameters that are being deliberately changed.
+.P
+The following
+.I mountflags
+can be changed:
+.BR MS_LAZYTIME ,
+.\" FIXME
+.\" MS_LAZYTIME seems to be available only on a few filesystems,
+.\" and on ext4, it seems (from experiment that this flag
+.\" can only be enabled (but not disabled) on a remount.
+.\" The following code in ext4_remount() (kernel 4.17) seems to
+.\" confirm this:
+.\"
+.\"        if (*flags & SB_LAZYTIME)
+.\"                sb->s_flags |= SB_LAZYTIME;
+.BR MS_MANDLOCK ,
+.BR MS_NOATIME ,
+.BR MS_NODEV ,
+.BR MS_NODIRATIME ,
+.BR MS_NOEXEC ,
+.BR MS_NOSUID ,
+.BR MS_RELATIME ,
+.BR MS_RDONLY ,
+.B MS_STRICTATIME
+(whose effect is to clear the
+.B MS_NOATIME
+and
+.B MS_RELATIME
+flags),
+and
+.BR MS_SYNCHRONOUS .
+Attempts to change the setting of the
+.\" See the definition of MS_RMT_MASK in include/uapi/linux/fs.h,
+.\" which excludes MS_DIRSYNC and MS_SILENT, although SB_DIRSYNC
+.\" and SB_SILENT are split out as per-superblock flags in do_mount()
+.\" (Linux 4.17 source code)
+.B MS_DIRSYNC
+and
+.B MS_SILENT
+flags during a remount are silently ignored.
+Note that changes to per-superblock flags are visible via
+all mounts of the associated filesystem
+(because the per-superblock flags are shared by all mounts).
+.P
+Since Linux 3.17,
+.\" commit ffbc6f0ead47fa5a1dc9642b0331cb75c20a640e
+if none of
+.BR MS_NOATIME ,
+.BR MS_NODIRATIME ,
+.BR MS_RELATIME ,
+or
+.B MS_STRICTATIME
+is specified in
+.IR mountflags ,
+then the remount operation preserves the existing values of these flags
+(rather than defaulting to
+.BR MS_RELATIME ).
+.P
+Since Linux 2.6.26, the
+.B MS_REMOUNT
+flag can be used with
+.B MS_BIND
+to modify only the per-mount-point flags.
+.\" See https://lwn.net/Articles/281157/
+This is particularly useful for setting or clearing the "read-only"
+flag on a mount without changing the underlying filesystem.
+Specifying
+.I mountflags
+as:
+.P
+.in +4n
+.EX
+MS_REMOUNT | MS_BIND | MS_RDONLY
+.EE
+.in
+.P
+will make access through this mountpoint read-only, without affecting
+other mounts.
+.\"
+.SS Creating a bind mount
+If
+.I mountflags
+includes
+.B MS_BIND
+(available since Linux 2.4),
+.\" since Linux 2.4.0-test9
+then perform a bind mount.
+A bind mount makes a file or a directory subtree visible at
+another point within the single directory hierarchy.
+Bind mounts may cross filesystem boundaries and span
+.BR chroot (2)
+jails.
+.P
+The
+.I filesystemtype
+and
+.I data
+arguments are ignored.
+.P
+The remaining bits (other than
+.BR MS_REC ,
+described below) in the
+.I mountflags
+argument are also ignored.
+(The bind mount has the same mount options as
+the underlying mount.)
+However, see the discussion of remounting above,
+for a method of making an existing bind mount read-only.
+.P
+By default, when a directory is bind mounted,
+only that directory is mounted;
+if there are any submounts under the directory tree,
+they are not bind mounted.
+If the
+.B MS_REC
+flag is also specified, then a recursive bind mount operation is performed:
+all submounts under the
+.I source
+subtree (other than unbindable mounts)
+are also bind mounted at the corresponding location in the
+.I target
+subtree.
+.\"
+.SS Changing the propagation type of an existing mount
+If
+.I mountflags
+includes one of
+.BR MS_SHARED ,
+.BR MS_PRIVATE ,
+.BR MS_SLAVE ,
+or
+.B MS_UNBINDABLE
+(all available since Linux 2.6.15),
+then the propagation type of an existing mount is changed.
+If more than one of these flags is specified, an error results.
+.P
+The only other flags that can be specified while changing
+the propagation type are
+.B MS_REC
+(described below) and
+.B MS_SILENT
+(which is ignored).
+.P
+The
+.IR source ,
+.IR filesystemtype ,
+and
+.I data
+arguments are ignored.
+.P
+The meanings of the propagation type flags are as follows:
+.TP
+.B MS_SHARED
+Make this mount shared.
+Mount and unmount events immediately under this mount will propagate
+to the other mounts that are members of this mount's peer group.
+Propagation here means that the same mount or unmount will automatically
+occur under all of the other mounts in the peer group.
+Conversely, mount and unmount events that take place under
+peer mounts will propagate to this mount.
+.TP
+.B MS_PRIVATE
+Make this mount private.
+Mount and unmount events do not propagate into or out of this mount.
+.TP
+.B MS_SLAVE
+If this is a shared mount that is a member of a peer group
+that contains other members, convert it to a slave mount.
+If this is a shared mount that is a member of a peer group
+that contains no other members, convert it to a private mount.
+Otherwise, the propagation type of the mount is left unchanged.
+.IP
+When a mount is a slave,
+mount and unmount events propagate into this mount from
+the (master) shared peer group of which it was formerly a member.
+Mount and unmount events under this mount do not propagate to any peer.
+.IP
+A mount can be the slave of another peer group
+while at the same time sharing mount and unmount events
+with a peer group of which it is a member.
+.TP
+.B MS_UNBINDABLE
+Make this mount unbindable.
+This is like a private mount,
+and in addition this mount can't be bind mounted.
+When a recursive bind mount
+.RB ( mount ()
+with the
+.B MS_BIND
+and
+.B MS_REC
+flags) is performed on a directory subtree,
+any unbindable mounts within the subtree are automatically pruned
+(i.e., not replicated)
+when replicating that subtree to produce the target subtree.
+.P
+By default, changing the propagation type affects only the
+.I target
+mount.
+If the
+.B MS_REC
+flag is also specified in
+.IR mountflags ,
+then the propagation type of all mounts under
+.I target
+is also changed.
+.P
+For further details regarding mount propagation types
+(including the default propagation type assigned to new mounts), see
+.BR mount_namespaces (7).
+.\"
+.SS Moving a mount
+If
+.I mountflags
+contains the flag
+.B MS_MOVE
+(available since Linux 2.4.18),
+then move a subtree:
+.I source
+specifies an existing mount and
+.I target
+specifies the new location to which that mount is to be relocated.
+The move is atomic: at no point is the subtree unmounted.
+.P
+The remaining bits in the
+.I mountflags
+argument are ignored, as are the
+.I filesystemtype
+and
+.I data
+arguments.
+.\"
+.SS Creating a new mount
+If none of
+.BR MS_REMOUNT ,
+.BR MS_BIND ,
+.BR MS_MOVE ,
+.BR MS_SHARED ,
+.BR MS_PRIVATE ,
+.BR MS_SLAVE ,
+or
+.B MS_UNBINDABLE
+is specified in
+.IR mountflags ,
+then
+.BR mount ()
+performs its default action: creating a new mount.
+.I source
+specifies the source for the new mount, and
+.I target
+specifies the directory at which to create the mount point.
+.P
+The
+.I filesystemtype
+and
+.I data
+arguments are employed, and further bits may be specified in
+.I mountflags
+to modify the behavior of the call.
+.\"
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The error values given below result from filesystem type independent
+errors.
+Each filesystem type may have its own special errors and its
+own special behavior.
+See the Linux kernel source code for details.
+.TP
+.B EACCES
+A component of a path was not searchable.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EACCES
+Mounting a read-only filesystem was attempted without giving the
+.B MS_RDONLY
+flag.
+.IP
+The filesystem may be read-only for various reasons, including:
+it resides on a read-only optical disk;
+it is resides on a device with a physical switch that has been set to
+mark the device read-only;
+the filesystem implementation was compiled with read-only support;
+or errors were detected when initially mounting the filesystem,
+so that it was marked read-only
+and can't be remounted as read-write (until the errors are fixed).
+.IP
+Some filesystems instead return the error
+.B EROFS
+on an attempt to mount a read-only filesystem.
+.TP
+.B EACCES
+The block device
+.I source
+is located on a filesystem mounted with the
+.B MS_NODEV
+option.
+.\" mtk: Probably: write permission is required for MS_BIND, with
+.\" the error EPERM if not present; CAP_DAC_OVERRIDE is required.
+.TP
+.B EBUSY
+An attempt was made to stack a new mount directly on
+top of an existing mount point that was created in this
+mount namespace with the same
+.I source
+and
+.IR target .
+.TP
+.B EBUSY
+.I source
+cannot be remounted read-only,
+because it still holds files open for writing.
+.TP
+.B EFAULT
+One of the pointer arguments points outside the user address space.
+.TP
+.B EINVAL
+.I source
+had an invalid superblock.
+.TP
+.B EINVAL
+A remount operation
+.RB ( MS_REMOUNT )
+was attempted, but
+.I source
+was not already mounted on
+.IR target .
+.TP
+.B EINVAL
+A move operation
+.RB ( MS_MOVE )
+was attempted, but the mount tree under
+.I source
+includes unbindable mounts and
+.I target
+is a mount that has propagation type
+.BR MS_SHARED .
+.TP
+.B EINVAL
+A move operation
+.RB ( MS_MOVE )
+was attempted, but the parent mount of
+.I source
+mount has propagation type
+.BR MS_SHARED .
+.TP
+.B EINVAL
+A move operation
+.RB ( MS_MOVE )
+was attempted, but
+.I source
+was not a mount, or was \[aq]/\[aq].
+.TP
+.B EINVAL
+A bind operation
+.RB ( MS_BIND )
+was requested where
+.I source
+referred a mount namespace magic link (i.e., a
+.IR /proc/ pid /ns/mnt
+magic link or a bind mount to such a link)
+and the propagation type of the parent mount of
+.I target
+was
+.BR MS_SHARED ,
+.\" See commit 8823c079ba7136dc1948d6f6dcb5f8022bde438e
+but propagation of the requested bind mount could lead to a circular
+dependency that might prevent the mount namespace from ever being freed.
+.TP
+.B EINVAL
+.I mountflags
+includes more than one of
+.BR MS_SHARED ,
+.BR MS_PRIVATE ,
+.BR MS_SLAVE ,
+or
+.BR MS_UNBINDABLE .
+.TP
+.B EINVAL
+.I mountflags
+includes
+.BR MS_SHARED ,
+.BR MS_PRIVATE ,
+.BR MS_SLAVE ,
+or
+.B MS_UNBINDABLE
+and also includes a flag other than
+.B MS_REC
+or
+.BR MS_SILENT .
+.TP
+.B EINVAL
+An attempt was made to bind mount an unbindable mount.
+.TP
+.B EINVAL
+In an unprivileged mount namespace
+(i.e., a mount namespace owned by a user namespace
+that was created by an unprivileged user),
+a bind mount operation
+.RB ( MS_BIND )
+was attempted without specifying
+.RB ( MS_REC ),
+which would have revealed the filesystem tree underneath one of
+the submounts of the directory being bound.
+.TP
+.B ELOOP
+Too many links encountered during pathname resolution.
+.TP
+.B ELOOP
+A move operation was attempted, and
+.I target
+is a descendant of
+.IR source .
+.TP
+.B EMFILE
+(In case no block device is required:)
+Table of dummy devices is full.
+.TP
+.B ENAMETOOLONG
+A pathname was longer than
+.BR MAXPATHLEN .
+.TP
+.B ENODEV
+.I filesystemtype
+not configured in the kernel.
+.TP
+.B ENOENT
+A pathname was empty or had a nonexistent component.
+.TP
+.B ENOMEM
+The kernel could not allocate a free page to copy filenames or data into.
+.TP
+.B ENOTBLK
+.I source
+is not a block device (and a device was required).
+.TP
+.B ENOTDIR
+.IR target ,
+or a prefix of
+.IR source ,
+is not a directory.
+.TP
+.B ENXIO
+The major number of the block device
+.I source
+is out of range.
+.TP
+.B EPERM
+The caller does not have the required privileges.
+.TP
+.B EPERM
+An attempt was made to modify
+.RB ( MS_REMOUNT )
+the
+.BR MS_RDONLY ,
+.BR MS_NOSUID ,
+or
+.B MS_NOEXEC
+flag, or one of the "atime" flags
+.RB ( MS_NOATIME ,
+.BR MS_NODIRATIME ,
+.BR MS_RELATIME )
+of an existing mount, but the mount is locked; see
+.BR mount_namespaces (7).
+.TP
+.B EROFS
+Mounting a read-only filesystem was attempted without giving the
+.B MS_RDONLY
+flag.
+See
+.BR EACCES ,
+above.
+.\"
+.SH STANDARDS
+Linux.
+.SH HISTORY
+The definitions of
+.BR MS_DIRSYNC ,
+.BR MS_MOVE ,
+.BR MS_PRIVATE ,
+.BR MS_REC ,
+.BR MS_RELATIME ,
+.BR MS_SHARED ,
+.BR MS_SLAVE ,
+.BR MS_STRICTATIME ,
+and
+.B MS_UNBINDABLE
+were added to glibc headers in glibc 2.12.
+.P
+Since Linux 2.4 a single filesystem can be mounted at
+multiple mount points, and multiple mounts can be stacked
+on the same mount point.
+.\" Multiple mounts on same mount point: since Linux 2.3.99pre7.
+.P
+The
+.I mountflags
+argument may have the magic number 0xC0ED (\fBMS_MGC_VAL\fP)
+in the top 16 bits.
+(All of the other flags discussed in DESCRIPTION
+occupy the low order 16 bits of
+.IR mountflags .)
+Specifying
+.B MS_MGC_VAL
+was required before Linux 2.4,
+but since Linux 2.4 is no longer required and is ignored if specified.
+.P
+The original
+.B MS_SYNC
+flag was renamed
+.B MS_SYNCHRONOUS
+in 1.1.69
+when a different
+.B MS_SYNC
+was added to \fI<mman.h>\fP.
+.P
+Before Linux 2.4 an attempt to execute a set-user-ID or set-group-ID program
+on a filesystem mounted with
+.B MS_NOSUID
+would fail with
+.BR EPERM .
+Since Linux 2.4 the set-user-ID and set-group-ID bits are
+just silently ignored in this case.
+.\" The change is in patch-2.4.0-prerelease.
+.\"
+.SH NOTES
+.SS Mount namespaces
+Starting with Linux 2.4.19, Linux provides mount namespaces.
+A mount namespace is the set of filesystem mounts that
+are visible to a process.
+Mount namespaces can be (and usually are)
+shared between multiple processes,
+and changes to the namespace (i.e., mounts and unmounts) by one process
+are visible to all other processes sharing the same namespace.
+(The pre-2.4.19 Linux situation can be considered as one in which
+a single namespace was shared by every process on the system.)
+.P
+A child process created by
+.BR fork (2)
+shares its parent's mount namespace;
+the mount namespace is preserved across an
+.BR execve (2).
+.P
+A process can obtain a private mount namespace if:
+it was created using the
+.BR clone (2)
+.B CLONE_NEWNS
+flag,
+in which case its new namespace is initialized to be a
+.I copy
+of the namespace of the process that called
+.BR clone (2);
+or it calls
+.BR unshare (2)
+with the
+.B CLONE_NEWNS
+flag,
+which causes the caller's mount namespace to obtain a private copy
+of the namespace that it was previously sharing with other processes,
+so that future mounts and unmounts by the caller are invisible
+to other processes (except child processes that the caller
+subsequently creates) and vice versa.
+.P
+For further details on mount namespaces, see
+.BR mount_namespaces (7).
+.\"
+.SS Parental relationship between mounts
+Each mount has a parent mount.
+The overall parental relationship of all mounts defines
+the single directory hierarchy seen by the processes within a mount namespace.
+.P
+The parent of a new mount is defined when the mount is created.
+In the usual case,
+the parent of a new mount is the mount of the filesystem
+containing the directory or file at which the new mount is attached.
+In the case where a new mount is stacked on top of an existing mount,
+the parent of the new mount is the previous mount that was stacked
+at that location.
+.P
+The parental relationship between mounts can be discovered via the
+.IR /proc/ pid /mountinfo
+file (see below).
+.\"
+.SS \fI/proc/\fPpid\fI/mounts\fP and \fI/proc/\fPpid\fI/mountinfo\fP
+The Linux-specific
+.IR /proc/ pid /mounts
+file exposes the list of mounts in the mount
+namespace of the process with the specified ID.
+The
+.IR /proc/ pid /mountinfo
+file exposes even more information about mounts,
+including the propagation type and mount ID information that makes it
+possible to discover the parental relationship between mounts.
+See
+.BR proc (5)
+and
+.BR mount_namespaces (7)
+for details of this file.
+.SH SEE ALSO
+.BR mountpoint (1),
+.BR chroot (2),
+.BR ioctl_iflags (2),
+.BR mount_setattr (2),
+.BR pivot_root (2),
+.BR umount (2),
+.BR mount_namespaces (7),
+.BR path_resolution (7),
+.BR findmnt (8),
+.BR lsblk (8),
+.BR mount (8),
+.BR umount (8)
diff --git a/man/man2/mount_setattr.2 b/man/man2/mount_setattr.2
new file mode 100644
index 000000000..f4bbc088b
--- /dev/null
+++ b/man/man2/mount_setattr.2
@@ -0,0 +1,1067 @@
+.\" Copyright (c) 2021 by Christian Brauner <christian.brauner@ubuntu.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mount_setattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mount_setattr \- change properties of a mount or mount tree
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/fcntl.h>" " /* Definition of " AT_* " constants */"
+.BR "#include <linux/mount.h>" " /* Definition of " MOUNT_ATTR_* " constants */"
+.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_mount_setattr, int " dirfd ", const char *" pathname ,
+.BI "            unsigned int " flags ", struct mount_attr *" attr \
+", size_t " size );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR mount_setattr (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR mount_setattr ()
+system call changes the mount properties of a mount or an entire mount tree.
+If
+.I pathname
+is a relative pathname,
+then it is interpreted relative to
+the directory referred to by the file descriptor
+.IR dirfd .
+If
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to
+the current working directory of the calling process.
+If
+.I pathname
+is the empty string and
+.B AT_EMPTY_PATH
+is specified in
+.IR flags ,
+then the mount properties of the mount identified by
+.I dirfd
+are changed.
+(See
+.BR openat (2)
+for an explanation of why the
+.I dirfd
+argument is useful.)
+.P
+The
+.BR mount_setattr ()
+system call uses an extensible structure
+.RI ( "struct mount_attr" )
+to allow for future extensions.
+Any non-flag extensions to
+.BR mount_setattr ()
+will be implemented as new fields appended to the this structure,
+with a zero value in a new field resulting in the kernel behaving
+as though that extension field was not present.
+Therefore,
+the caller
+.I must
+zero-fill this structure on initialization.
+See the "Extensibility" subsection under
+.B NOTES
+for more details.
+.P
+The
+.I size
+argument should usually be specified as
+.IR "sizeof(struct mount_attr)" .
+However, if the caller is using a kernel that supports an extended
+.IR "struct mount_attr" ,
+but the caller does not intend to make use of these features,
+it is possible to pass the size of an earlier
+version of the structure together with the extended structure.
+This allows the kernel to not copy later parts of the structure
+that aren't used anyway.
+With each extension that changes the size of
+.IR "struct mount_attr" ,
+the kernel will expose a definition of the form
+.BI MOUNT_ATTR_SIZE_VER number\c
+\&.
+For example, the macro for the size of the initial version of
+.I struct mount_attr
+is
+.BR MOUNT_ATTR_SIZE_VER0 .
+.P
+The
+.I flags
+argument can be used to alter the pathname resolution behavior.
+The supported values are:
+.TP
+.B AT_EMPTY_PATH
+If
+.I pathname
+is the empty string,
+change the mount properties on
+.I dirfd
+itself.
+.TP
+.B AT_RECURSIVE
+Change the mount properties of the entire mount tree.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+Don't follow trailing symbolic links.
+.TP
+.B AT_NO_AUTOMOUNT
+Don't trigger automounts.
+.P
+The
+.I attr
+argument of
+.BR mount_setattr ()
+is a structure of the following form:
+.P
+.in +4n
+.EX
+struct mount_attr {
+    __u64 attr_set;     /* Mount properties to set */
+    __u64 attr_clr;     /* Mount properties to clear */
+    __u64 propagation;  /* Mount propagation type */
+    __u64 userns_fd;    /* User namespace file descriptor */
+};
+.EE
+.in
+.P
+The
+.I attr_set
+and
+.I attr_clr
+members are used to specify the mount properties that
+are supposed to be set or cleared for a mount or mount tree.
+Flags set in
+.I attr_set
+enable a property on a mount or mount tree,
+and flags set in
+.I attr_clr
+remove a property from a mount or mount tree.
+.P
+When changing mount properties,
+the kernel will first clear the flags specified
+in the
+.I attr_clr
+field,
+and then set the flags specified in the
+.I attr_set
+field.
+For example, these settings:
+.P
+.in +4n
+.EX
+struct mount_attr attr = {
+    .attr_clr = MOUNT_ATTR_NOEXEC | MOUNT_ATTR_NODEV,
+    .attr_set = MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID,
+};
+.EE
+.in
+.P
+are equivalent to the following steps:
+.P
+.in +4n
+.EX
+unsigned int current_mnt_flags = mnt\->mnt_flags;
+\&
+/*
+ * Clear all flags set in .attr_clr,
+ * clearing MOUNT_ATTR_NOEXEC and MOUNT_ATTR_NODEV.
+ */
+current_mnt_flags &= \(tiattr\->attr_clr;
+\&
+/*
+ * Now set all flags set in .attr_set,
+ * applying MOUNT_ATTR_RDONLY and MOUNT_ATTR_NOSUID.
+ */
+current_mnt_flags |= attr\->attr_set;
+\&
+mnt\->mnt_flags = current_mnt_flags;
+.EE
+.in
+.P
+As a result of this change, the mount or mount tree (a) is read-only;
+(b) blocks the execution of set-user-ID and set-group-ID programs;
+(c) allows execution of programs; and (d) allows access to devices.
+.P
+Multiple changes with the same set of flags requested
+in
+.I attr_clr
+and
+.I attr_set
+are guaranteed to be idempotent after the changes have been applied.
+.P
+The following mount attributes can be specified in the
+.I attr_set
+or
+.I attr_clr
+fields:
+.TP
+.B MOUNT_ATTR_RDONLY
+If set in
+.IR attr_set ,
+makes the mount read-only.
+If set in
+.IR attr_clr ,
+removes the read-only setting if set on the mount.
+.TP
+.B MOUNT_ATTR_NOSUID
+If set in
+.IR attr_set ,
+causes the mount not to honor the set-user-ID and set-group-ID mode bits and
+file capabilities when executing programs.
+If set in
+.IR attr_clr ,
+clears the set-user-ID, set-group-ID,
+and file capability restriction if set on this mount.
+.TP
+.B MOUNT_ATTR_NODEV
+If set in
+.IR attr_set ,
+prevents access to devices on this mount.
+If set in
+.IR attr_clr ,
+removes the restriction that prevented accessing devices on this mount.
+.TP
+.B MOUNT_ATTR_NOEXEC
+If set in
+.IR attr_set ,
+prevents executing programs on this mount.
+If set in
+.IR attr_clr ,
+removes the restriction that prevented executing programs on this mount.
+.TP
+.B MOUNT_ATTR_NOSYMFOLLOW
+If set in
+.IR attr_set ,
+prevents following symbolic links on this mount.
+If set in
+.IR attr_clr ,
+removes the restriction that prevented following symbolic links on this mount.
+.TP
+.B MOUNT_ATTR_NODIRATIME
+If set in
+.IR attr_set ,
+prevents updating access time for directories on this mount.
+If set in
+.IR attr_clr ,
+removes the restriction that prevented updating access time for directories.
+Note that
+.B MOUNT_ATTR_NODIRATIME
+can be combined with other access-time settings
+and is implied by the noatime setting.
+All other access-time settings are mutually exclusive.
+.TP
+.BR MOUNT_ATTR__ATIME " - changing access-time settings"
+The access-time values listed below are an enumeration that
+includes the value zero, expressed in the bits defined by the mask
+.BR MOUNT_ATTR__ATIME .
+Even though these bits are an enumeration
+(in contrast to the other mount flags such as
+.BR MOUNT_ATTR_NOEXEC ),
+they are nonetheless passed in
+.I attr_set
+and
+.I attr_clr
+for consistency with
+.BR fsmount (2),
+which introduced this behavior.
+.IP
+Note that,
+since the access-time values are an enumeration rather than bit values,
+a caller wanting to transition to a different access-time setting
+cannot simply specify the access-time setting in
+.IR attr_set ,
+but must also include
+.B MOUNT_ATTR__ATIME
+in the
+.I attr_clr
+field.
+The kernel will verify that
+.B MOUNT_ATTR__ATIME
+isn't partially set in
+.I attr_clr
+(i.e., either all bits in the
+.B MOUNT_ATTR__ATIME
+bit field are either set or clear), and that
+.I attr_set
+doesn't have any access-time bits set if
+.B MOUNT_ATTR__ATIME
+isn't set in
+.IR attr_clr .
+.RS
+.TP
+.B MOUNT_ATTR_RELATIME
+When a file is accessed via this mount,
+update the file's last access time (atime)
+only if the current value of atime is less than or equal to
+the file's last modification time (mtime) or last status change time (ctime).
+.IP
+To enable this access-time setting on a mount or mount tree,
+.B MOUNT_ATTR_RELATIME
+must be set in
+.I attr_set
+and
+.B MOUNT_ATTR__ATIME
+must be set in the
+.I attr_clr
+field.
+.TP
+.B MOUNT_ATTR_NOATIME
+Do not update access times for (all types of) files on this mount.
+.IP
+To enable this access-time setting on a mount or mount tree,
+.B MOUNT_ATTR_NOATIME
+must be set in
+.I attr_set
+and
+.B MOUNT_ATTR__ATIME
+must be set in the
+.I attr_clr
+field.
+.TP
+.B MOUNT_ATTR_STRICTATIME
+Always update the last access time (atime)
+when files are accessed on this mount.
+.IP
+To enable this access-time setting on a mount or mount tree,
+.B MOUNT_ATTR_STRICTATIME
+must be set in
+.I attr_set
+and
+.B MOUNT_ATTR__ATIME
+must be set in the
+.I attr_clr
+field.
+.RE
+.TP
+.B MOUNT_ATTR_IDMAP
+If set in
+.IR attr_set ,
+creates an ID-mapped mount.
+The ID mapping is taken from the user namespace specified in
+.I userns_fd
+and attached to the mount.
+.IP
+Since it is not supported to
+change the ID mapping of a mount after it has been ID mapped,
+it is invalid to specify
+.B MOUNT_ATTR_IDMAP
+in
+.IR attr_clr .
+.IP
+For further details, see the subsection "ID-mapped mounts" under NOTES.
+.P
+The
+.I propagation
+field is used to specify the propagation type of the mount or mount tree.
+This field either has the value zero,
+meaning leave the propagation type unchanged, or it has one of
+the following values:
+.TP
+.B MS_PRIVATE
+Turn all mounts into private mounts.
+.TP
+.B MS_SHARED
+Turn all mounts into shared mounts.
+.TP
+.B MS_SLAVE
+Turn all mounts into dependent mounts.
+.TP
+.B MS_UNBINDABLE
+Turn all mounts into unbindable mounts.
+.P
+For further details on the above propagation types, see
+.BR mount_namespaces (7).
+.SH RETURN VALUE
+On success,
+.BR mount_setattr ()
+returns zero.
+On error,
+\-1 is returned and
+.I errno
+is set to indicate the cause of the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EBADF
+.I userns_fd
+is not a valid file descriptor.
+.TP
+.B EBUSY
+The caller tried to change the mount to
+.BR MOUNT_ATTR_RDONLY ,
+but the mount still holds files open for writing.
+.TP
+.B EBUSY
+The caller tried to create an ID-mapped mount raising
+.B MOUNT_ATTR_IDMAP
+and specifying
+.I userns_fd
+but the mount still holds files open for writing.
+.TP
+.B EINVAL
+The pathname specified via the
+.I dirfd
+and
+.I pathname
+arguments to
+.BR mount_setattr ()
+isn't a mount point.
+.TP
+.B EINVAL
+An unsupported value was set in
+.IR flags .
+.TP
+.B EINVAL
+An unsupported value was specified in the
+.I attr_set
+field of
+.IR mount_attr .
+.TP
+.B EINVAL
+An unsupported value was specified in the
+.I attr_clr
+field of
+.IR mount_attr .
+.TP
+.B EINVAL
+An unsupported value was specified in the
+.I propagation
+field of
+.IR mount_attr .
+.TP
+.B EINVAL
+More than one of
+.BR MS_SHARED ,
+.BR MS_SLAVE ,
+.BR MS_PRIVATE ,
+or
+.B MS_UNBINDABLE
+was set in the
+.I propagation
+field of
+.IR mount_attr .
+.TP
+.B EINVAL
+An access-time setting was specified in the
+.I attr_set
+field without
+.B MOUNT_ATTR__ATIME
+being set in the
+.I attr_clr
+field.
+.TP
+.B EINVAL
+.B MOUNT_ATTR_IDMAP
+was specified in
+.IR attr_clr .
+.TP
+.B EINVAL
+A file descriptor value was specified in
+.I userns_fd
+which exceeds
+.BR INT_MAX .
+.TP
+.B EINVAL
+A valid file descriptor value was specified in
+.IR userns_fd ,
+but the file descriptor did not refer to a user namespace.
+.TP
+.B EINVAL
+The underlying filesystem does not support ID-mapped mounts.
+.TP
+.B EINVAL
+The mount that is to be ID mapped is not a detached mount;
+that is, the mount has not previously been visible in a mount namespace.
+.TP
+.B EINVAL
+A partial access-time setting was specified in
+.I attr_clr
+instead of
+.B MOUNT_ATTR__ATIME
+being set.
+.TP
+.B EINVAL
+The mount is located outside the caller's mount namespace.
+.TP
+.B EINVAL
+The underlying filesystem has been mounted in a mount namespace that is
+owned by a noninitial user namespace
+.TP
+.B ENOENT
+A pathname was empty or had a nonexistent component.
+.TP
+.B ENOMEM
+When changing mount propagation to
+.BR MS_SHARED ,
+a new peer group ID needs to be allocated for all mounts without a peer group
+ID set.
+This allocation failed because there was not
+enough memory to allocate the relevant internal structures.
+.TP
+.B ENOSPC
+When changing mount propagation to
+.BR MS_SHARED ,
+a new peer group ID needs to be allocated for all mounts without a peer group
+ID set.
+This allocation failed because
+the kernel has run out of IDs.
+.\" Christian Brauner: i.e. someone has somehow managed to
+.\" allocate so many peer groups and managed to keep the kernel running
+.\" (???) that the ida has ran out of ids
+.\" Note that technically further error codes are possible that are
+.\" specific to the ID allocation implementation used.
+.TP
+.B EPERM
+One of the mounts had at least one of
+.BR MOUNT_ATTR_NOATIME ,
+.BR MOUNT_ATTR_NODEV ,
+.BR MOUNT_ATTR_NODIRATIME ,
+.BR MOUNT_ATTR_NOEXEC ,
+.BR MOUNT_ATTR_NOSUID ,
+or
+.B MOUNT_ATTR_RDONLY
+set and the flag is locked.
+Mount attributes become locked on a mount if:
+.RS
+.IP \[bu] 3
+A new mount or mount tree is created causing mount propagation across user
+namespaces
+(i.e., propagation to a mount namespace owned by a different user namespace).
+The kernel will lock the aforementioned flags to prevent these sensitive
+properties from being altered.
+.IP \[bu]
+A new mount and user namespace pair is created.
+This happens for example when specifying
+.B CLONE_NEWUSER | CLONE_NEWNS
+in
+.BR unshare (2),
+.BR clone (2),
+or
+.BR clone3 (2).
+The aforementioned flags become locked in the new mount namespace
+to prevent sensitive mount properties from being altered.
+Since the newly created mount namespace will be owned by the
+newly created user namespace,
+a calling process that is privileged in the new
+user namespace would\[em]in the absence of such locking\[em]be
+able to alter sensitive mount properties (e.g., to remount a mount
+that was marked read-only as read-write in the new mount namespace).
+.RE
+.TP
+.B EPERM
+A valid file descriptor value was specified in
+.IR userns_fd ,
+but the file descriptor refers to the initial user namespace.
+.TP
+.B EPERM
+An attempt was made to add an ID mapping to a mount that is already ID mapped.
+.TP
+.B EPERM
+The caller does not have
+.B CAP_SYS_ADMIN
+in the initial user namespace.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.12.
+.\" commit 7d6beb71da3cc033649d641e1e608713b8220290
+.\" commit 2a1867219c7b27f928e2545782b86daaf9ad50bd
+.\" commit 9caccd41541a6f7d6279928d9f971f6642c361af
+.SH NOTES
+.SS ID-mapped mounts
+Creating an ID-mapped mount makes it possible to
+change the ownership of all files located under a mount.
+Thus, ID-mapped mounts make it possible to
+change ownership in a temporary and localized way.
+It is a localized change because the ownership changes are
+visible only via a specific mount.
+All other users and locations where the filesystem is exposed are unaffected.
+It is a temporary change because
+the ownership changes are tied to the lifetime of the mount.
+.P
+Whenever callers interact with the filesystem through an ID-mapped mount,
+the ID mapping of the mount will be applied to
+user and group IDs associated with filesystem objects.
+This encompasses the user and group IDs associated with inodes
+and also the following
+.BR xattr (7)
+keys:
+.IP \[bu] 3
+.IR security.capability ,
+whenever filesystem capabilities
+are stored or returned in the
+.B VFS_CAP_REVISION_3
+format,
+which stores a root user ID alongside the capabilities
+(see
+.BR capabilities (7)).
+.IP \[bu]
+.I system.posix_acl_access
+and
+.IR system.posix_acl_default ,
+whenever user IDs or group IDs are stored in
+.B ACL_USER
+or
+.B ACL_GROUP
+entries.
+.P
+The following conditions must be met in order to create an ID-mapped mount:
+.IP \[bu] 3
+The caller must have the
+.B CAP_SYS_ADMIN
+capability in the user namespace the filesystem was mounted in.
+.\" commit bd303368b776eead1c29e6cdda82bde7128b82a7
+.\" Christian Brauner
+.\"     Note, currently no filesystems mountable in non-initial user namespaces
+.\"     support ID-mapped mounts.
+.IP \[bu]
+The underlying filesystem must support ID-mapped mounts.
+Currently, the following filesystems support ID-mapped mounts:
+.\" fs_flags = FS_ALLOW_IDMAP in kernel sources
+.RS
+.IP \[bu] 3
+.PD 0
+.BR xfs (5)
+(since Linux 5.12)
+.IP \[bu]
+.BR ext4 (5)
+(since Linux 5.12)
+.IP \[bu]
+.B FAT
+(since Linux 5.12)
+.IP \[bu]
+.BR btrfs (5)
+(since Linux 5.15)
+.\" commit 5b9b26f5d0b88b74001dcfe4ab8a8f2f4e744112
+.IP \[bu]
+.B ntfs3
+(since Linux 5.15)
+.\" commit 82cae269cfa953032fbb8980a7d554d60fb00b17
+.IP \[bu]
+.B f2fs
+(since Linux 5.18)
+.\" commit 984fc4e76d63345499f01c0c198a4b44860cf027
+.IP \[bu]
+.B erofs
+(since Linux 5.19)
+.\" commit 6c459b78d4793afbba6d864c466cc5cd2932459d
+.IP \[bu]
+.B overlayfs
+(ID-mapped lower and upper layers supported since Linux 5.19)
+.IP \[bu]
+.B squashfs
+(since Linux 6.2)
+.IP \[bu]
+.B tmpfs
+(since Linux 6.3)
+.IP \[bu]
+.B cephfs
+(since Linux 6.7)
+.IP \[bu]
+.B hugetlbfs
+(since Linux 6.9)
+.PD
+.RE
+.IP \[bu]
+The mount must not already be ID-mapped.
+This also implies that the ID mapping of a mount cannot be altered.
+.IP \[bu]
+The mount must not have any writers.
+.\" commit 1bbcd277a53e08d619ffeec56c5c9287f2bf42f
+.IP \[bu]
+The mount must be a detached mount;
+that is,
+it must have been created by calling
+.BR open_tree (2)
+with the
+.B OPEN_TREE_CLONE
+flag and it must not already have been visible in a mount namespace.
+(To put things another way:
+the mount must not have been attached to the filesystem hierarchy
+with a system call such as
+.BR move_mount (2).)
+.P
+ID mappings can be created for user IDs, group IDs, and project IDs.
+An ID mapping is essentially a mapping of a range of user or group IDs into
+another or the same range of user or group IDs.
+ID mappings are written to map files as three numbers
+separated by white space.
+The first two numbers specify the starting user or group ID
+in each of the two user namespaces.
+The third number specifies the range of the ID mapping.
+For example,
+a mapping for user IDs such as "1000\ 1001\ 1" would indicate that
+user ID 1000 in the caller's user namespace is mapped to
+user ID 1001 in its ancestor user namespace.
+Since the map range is 1,
+only user ID 1000 is mapped.
+.P
+It is possible to specify up to 340 ID mappings for each ID mapping type.
+If any user IDs or group IDs are not mapped,
+all files owned by that unmapped user or group ID will appear as
+being owned by the overflow user ID or overflow group ID respectively.
+.P
+Further details on setting up ID mappings can be found in
+.BR user_namespaces (7).
+.P
+In the common case, the user namespace passed in
+.I userns_fd
+(together with
+.B MOUNT_ATTR_IDMAP
+in
+.IR attr_set )
+to create an ID-mapped mount will be the user namespace of a container.
+In other scenarios it will be a dedicated user namespace associated with
+a user's login session as is the case for portable home directories in
+.BR systemd-homed.service (8)).
+It is also perfectly fine to create a dedicated user namespace
+for the sake of ID mapping a mount.
+.P
+ID-mapped mounts can be useful in the following
+and a variety of other scenarios:
+.IP \[bu] 3
+Sharing files or filesystems
+between multiple users or multiple machines,
+especially in complex scenarios.
+For example,
+ID-mapped mounts are used to implement portable home directories in
+.BR systemd-homed.service (8),
+where they allow users to move their home directory
+to an external storage device
+and use it on multiple computers
+where they are assigned different user IDs and group IDs.
+This effectively makes it possible to
+assign random user IDs and group IDs at login time.
+.IP \[bu]
+Sharing files or filesystems
+from the host with unprivileged containers.
+This allows a user to avoid having to change ownership permanently through
+.BR chown (2).
+.IP \[bu]
+ID mapping a container's root filesystem.
+Users don't need to change ownership permanently through
+.BR chown (2).
+Especially for large root filesystems, using
+.BR chown (2)
+can be prohibitively expensive.
+.IP \[bu]
+Sharing files or filesystems
+between containers with non-overlapping ID mappings.
+.IP \[bu]
+Implementing discretionary access (DAC) permission checking
+for filesystems lacking a concept of ownership.
+.IP \[bu]
+Efficiently changing ownership on a per-mount basis.
+In contrast to
+.BR chown (2),
+changing ownership of large sets of files is instantaneous with
+ID-mapped mounts.
+This is especially useful when ownership of
+an entire root filesystem of a virtual machine or container
+is to be changed as mentioned above.
+With ID-mapped mounts,
+a single
+.BR mount_setattr ()
+system call will be sufficient to change the ownership of all files.
+.IP \[bu]
+Taking the current ownership into account.
+ID mappings specify precisely
+what a user or group ID is supposed to be mapped to.
+This contrasts with the
+.BR chown (2)
+system call which cannot by itself
+take the current ownership of the files it changes into account.
+It simply changes the ownership to the specified user ID and group ID.
+.IP \[bu]
+Locally and temporarily restricted ownership changes.
+ID-mapped mounts make it possible to change ownership locally,
+restricting the ownership changes to specific mounts,
+and temporarily as the ownership changes only apply as long as the mount exists.
+By contrast,
+changing ownership via the
+.BR chown (2)
+system call changes the ownership globally and permanently.
+.\"
+.SS Extensibility
+In order to allow for future extensibility,
+.BR mount_setattr ()
+requires the user-space application to specify the size of the
+.I mount_attr
+structure that it is passing.
+By providing this information, it is possible for
+.BR mount_setattr ()
+to provide both forwards- and backwards-compatibility, with
+.I size
+acting as an implicit version number.
+(Because new extension fields will always
+be appended, the structure size will always increase.)
+This extensibility design is very similar to other system calls such as
+.BR perf_setattr (2),
+.BR perf_event_open (2),
+.BR clone3 (2)
+and
+.BR openat2 (2).
+.P
+Let
+.I usize
+be the size of the structure as specified by the user-space application,
+and let
+.I ksize
+be the size of the structure which the kernel supports,
+then there are three cases to consider:
+.IP \[bu] 3
+If
+.I ksize
+equals
+.IR usize ,
+then there is no version mismatch and
+.I attr
+can be used verbatim.
+.IP \[bu]
+If
+.I ksize
+is larger than
+.IR usize ,
+then there are some extension fields that the kernel supports
+which the user-space application is unaware of.
+Because a zero value in any added extension field signifies a no-op,
+the kernel treats all of the extension fields
+not provided by the user-space application
+as having zero values.
+This provides backwards-compatibility.
+.IP \[bu]
+If
+.I ksize
+is smaller than
+.IR usize ,
+then there are some extension fields which the user-space application is aware
+of but which the kernel does not support.
+Because any extension field must have its zero values signify a no-op,
+the kernel can safely ignore the unsupported extension fields
+if they are all zero.
+If any unsupported extension fields are non-zero,
+then \-1 is returned and
+.I errno
+is set to
+.BR E2BIG .
+This provides forwards-compatibility.
+.P
+Because the definition of
+.I struct mount_attr
+may change in the future
+(with new fields being added when system headers are updated),
+user-space applications should zero-fill
+.I struct mount_attr
+to ensure that recompiling the program with new headers will not result in
+spurious errors at run time.
+The simplest way is to use a designated initializer:
+.P
+.in +4n
+.EX
+struct mount_attr attr = {
+    .attr_set = MOUNT_ATTR_RDONLY,
+    .attr_clr = MOUNT_ATTR_NODEV
+};
+.EE
+.in
+.P
+Alternatively, the structure can be zero-filled using
+.BR memset (3)
+or similar functions:
+.P
+.in +4n
+.EX
+struct mount_attr attr;
+memset(&attr, 0, sizeof(attr));
+attr.attr_set = MOUNT_ATTR_RDONLY;
+attr.attr_clr = MOUNT_ATTR_NODEV;
+.EE
+.in
+.P
+A user-space application that wishes to determine which extensions the running
+kernel supports can do so by conducting a binary search on
+.I size
+with a structure which has every byte nonzero
+(to find the largest value which doesn't produce an error of
+.BR E2BIG ).
+.SH EXAMPLES
+.\" SRC BEGIN (mount_setattr.c)
+.EX
+/*
+ * This program allows the caller to create a new detached mount
+ * and set various properties on it.
+ */
+#define _GNU_SOURCE
+#include <err.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <linux/mount.h>
+#include <linux/types.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+static inline int
+mount_setattr(int dirfd, const char *pathname, unsigned int flags,
+              struct mount_attr *attr, size_t size)
+{
+    return syscall(SYS_mount_setattr, dirfd, pathname, flags,
+                   attr, size);
+}
+\&
+static inline int
+open_tree(int dirfd, const char *filename, unsigned int flags)
+{
+    return syscall(SYS_open_tree, dirfd, filename, flags);
+}
+\&
+static inline int
+move_mount(int from_dirfd, const char *from_pathname,
+           int to_dirfd, const char *to_pathname, unsigned int flags)
+{
+    return syscall(SYS_move_mount, from_dirfd, from_pathname,
+                   to_dirfd, to_pathname, flags);
+}
+\&
+static const struct option longopts[] = {
+    {"map\-mount",       required_argument,  NULL,  \[aq]a\[aq]},
+    {"recursive",       no_argument,        NULL,  \[aq]b\[aq]},
+    {"read\-only",       no_argument,        NULL,  \[aq]c\[aq]},
+    {"block\-setid",     no_argument,        NULL,  \[aq]d\[aq]},
+    {"block\-devices",   no_argument,        NULL,  \[aq]e\[aq]},
+    {"block\-exec",      no_argument,        NULL,  \[aq]f\[aq]},
+    {"no\-access\-time",  no_argument,        NULL,  \[aq]g\[aq]},
+    { NULL,             0,                  NULL,   0 },
+};
+\&
+int
+main(int argc, char *argv[])
+{
+    int                fd_userns = \-1;
+    int                fd_tree;
+    int                index = 0;
+    int                ret;
+    bool               recursive = false;
+    const char         *source;
+    const char         *target;
+    struct mount_attr  *attr = &(struct mount_attr){};
+\&
+    while ((ret = getopt_long_only(argc, argv, "",
+                                   longopts, &index)) != \-1) {
+        switch (ret) {
+        case \[aq]a\[aq]:
+            fd_userns = open(optarg, O_RDONLY | O_CLOEXEC);
+            if (fd_userns == \-1)
+                err(EXIT_FAILURE, "open(%s)", optarg);
+            break;
+        case \[aq]b\[aq]:
+            recursive = true;
+            break;
+        case \[aq]c\[aq]:
+            attr\->attr_set |= MOUNT_ATTR_RDONLY;
+            break;
+        case \[aq]d\[aq]:
+            attr\->attr_set |= MOUNT_ATTR_NOSUID;
+            break;
+        case \[aq]e\[aq]:
+            attr\->attr_set |= MOUNT_ATTR_NODEV;
+            break;
+        case \[aq]f\[aq]:
+            attr\->attr_set |= MOUNT_ATTR_NOEXEC;
+            break;
+        case \[aq]g\[aq]:
+            attr\->attr_set |= MOUNT_ATTR_NOATIME;
+            attr\->attr_clr |= MOUNT_ATTR__ATIME;
+            break;
+        default:
+            errx(EXIT_FAILURE, "Invalid argument specified");
+        }
+    }
+\&
+    if ((argc \- optind) < 2)
+        errx(EXIT_FAILURE, "Missing source or target mount point");
+\&
+    source = argv[optind];
+    target = argv[optind + 1];
+\&
+    /* In the following, \-1 as the \[aq]dirfd\[aq] argument ensures that
+       open_tree() fails if \[aq]source\[aq] is not an absolute pathname. */
+.\" Christian Brauner
+.\"     When writing programs I like to never use relative paths with AT_FDCWD
+.\"     because. Because making assumptions about the current working directory
+.\"     of the calling process is just too easy to get wrong; especially when
+.\"     pivot_root() or chroot() are in play.
+.\"     My absolut preference (joke intended) is to open a well-known starting
+.\"     point with an absolute path to get a dirfd and then scope all future
+.\"     operations beneath that dirfd. This already works with old-style
+.\"     openat() and _very_ cautious programming but openat2() and its
+.\"     resolve-flag space have made this **chef's kiss**.
+.\"     If I can't operate based on a well-known dirfd I use absolute paths
+.\"     with a -EBADF dirfd passed to *at() functions.
+\&
+    fd_tree = open_tree(\-1, source,
+                        OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC |
+                        AT_EMPTY_PATH | (recursive ? AT_RECURSIVE : 0));
+    if (fd_tree == \-1)
+        err(EXIT_FAILURE, "open(%s)", source);
+\&
+    if (fd_userns >= 0) {
+        attr\->attr_set  |= MOUNT_ATTR_IDMAP;
+        attr\->userns_fd = fd_userns;
+    }
+\&
+    ret = mount_setattr(fd_tree, "",
+                        AT_EMPTY_PATH | (recursive ? AT_RECURSIVE : 0),
+                        attr, sizeof(struct mount_attr));
+    if (ret == \-1)
+        err(EXIT_FAILURE, "mount_setattr");
+\&
+    close(fd_userns);
+\&
+    /* In the following, \-1 as the \[aq]to_dirfd\[aq] argument ensures that
+       open_tree() fails if \[aq]target\[aq] is not an absolute pathname. */
+\&
+    ret = move_mount(fd_tree, "", \-1, target,
+                     MOVE_MOUNT_F_EMPTY_PATH);
+    if (ret == \-1)
+        err(EXIT_FAILURE, "move_mount() to %s", target);
+\&
+    close(fd_tree);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR newgidmap (1),
+.BR newuidmap (1),
+.BR clone (2),
+.BR mount (2),
+.BR unshare (2),
+.BR proc (5),
+.BR capabilities (7),
+.BR mount_namespaces (7),
+.BR user_namespaces (7),
+.BR xattr (7)
diff --git a/man/man2/move_pages.2 b/man/man2/move_pages.2
new file mode 100644
index 000000000..1b6281bd5
--- /dev/null
+++ b/man/man2/move_pages.2
@@ -0,0 +1,253 @@
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" This manpage is Copyright (C) 2006 Silicon Graphics, Inc.
+.\"                               Christoph Lameter
+.\"
+.\" FIXME Should programs normally be using move_pages() directly, or should
+.\" they rather be using interfaces in the numactl package?
+.\" (e.g., compare with recommendation in mbind(2)).
+.\" Does this page need to give advice on this topic?
+.\"
+.TH move_pages 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+move_pages \- move individual pages of a process to another node
+.SH LIBRARY
+NUMA (Non-Uniform Memory Access) policy library
+.RI ( libnuma ", " \-lnuma )
+.SH SYNOPSIS
+.nf
+.B #include <numaif.h>
+.P
+.BI "long move_pages(int " pid ", unsigned long " count ", \
+void *" pages [. count ],
+.BI "                const int " nodes [. count "], int " status [. count "], \
+int " flags );
+.fi
+.SH DESCRIPTION
+.BR move_pages ()
+moves the specified
+.I pages
+of the process
+.I pid
+to the memory nodes specified by
+.IR nodes .
+The result of the move is reflected in
+.IR status .
+The
+.I flags
+indicate constraints on the pages to be moved.
+.P
+.I pid
+is the ID of the process in which pages are to be moved.
+If
+.I pid
+is 0, then
+.BR move_pages ()
+moves pages of the calling process.
+.P
+To move pages in another process requires the following privileges:
+.IP \[bu] 3
+Up to and including Linux 4.12:
+the caller must be privileged
+.RB ( CAP_SYS_NICE )
+or the real or effective user ID of the calling process must match the
+real or saved-set user ID of the target process.
+.IP \[bu]
+The older rules allowed the caller to discover various
+virtual address choices made by the kernel that could lead
+to the defeat of address-space-layout randomization
+for a process owned by the same UID as the caller,
+the rules were changed starting with Linux 4.13.
+Since Linux 4.13,
+.\" commit 197e7e521384a23b9e585178f3f11c9fa08274b9
+permission is governed by a ptrace access mode
+.B PTRACE_MODE_READ_REALCREDS
+check with respect to the target process; see
+.BR ptrace (2).
+.P
+.I count
+is the number of pages to move.
+It defines the size of the three arrays
+.IR pages ,
+.IR nodes ,
+and
+.IR status .
+.P
+.I pages
+is an array of pointers to the pages that should be moved.
+These are pointers that should be aligned to page boundaries.
+.\" FIXME Describe the result if pointers in the 'pages' array are
+.\" not aligned to page boundaries
+Addresses are specified as seen by the process specified by
+.IR pid .
+.P
+.I nodes
+is an array of integers that specify the desired location for each page.
+Each element in the array is a node number.
+.I nodes
+can also be NULL, in which case
+.BR move_pages ()
+does not move any pages but instead will return the node
+where each page currently resides, in the
+.I status
+array.
+Obtaining the status of each page may be necessary to determine
+pages that need to be moved.
+.P
+.I status
+is an array of integers that return the status of each page.
+The array contains valid values only if
+.BR move_pages ()
+did not return an error.
+Preinitialization of the array to a value
+which cannot represent a real numa node or valid error of status array
+could help to identify pages that have been migrated.
+.P
+.I flags
+specify what types of pages to move.
+.B MPOL_MF_MOVE
+means that only pages that are in exclusive use by the process
+are to be moved.
+.B MPOL_MF_MOVE_ALL
+means that pages shared between multiple processes can also be moved.
+The process must be privileged
+.RB ( CAP_SYS_NICE )
+to use
+.BR MPOL_MF_MOVE_ALL .
+.SS Page states in the status array
+The following values can be returned in each element of the
+.I status
+array.
+.TP
+.B 0..MAX_NUMNODES
+Identifies the node on which the page resides.
+.TP
+.B \-EACCES
+The page is mapped by multiple processes and can be moved only if
+.B MPOL_MF_MOVE_ALL
+is specified.
+.TP
+.B \-EBUSY
+The page is currently busy and cannot be moved.
+Try again later.
+This occurs if a page is undergoing I/O or another kernel subsystem
+is holding a reference to the page.
+.TP
+.B \-EFAULT
+This is a zero page or the memory area is not mapped by the process.
+.TP
+.B \-EIO
+Unable to write back a page.
+The page has to be written back
+in order to move it since the page is dirty and the filesystem
+does not provide a migration function that would allow the move
+of dirty pages.
+.TP
+.B \-EINVAL
+A dirty page cannot be moved.
+The filesystem does not
+provide a migration function and has no ability to write back pages.
+.TP
+.B \-ENOENT
+The page is not present.
+.TP
+.B \-ENOMEM
+Unable to allocate memory on target node.
+.SH RETURN VALUE
+On success
+.BR move_pages ()
+returns zero.
+.\" FIXME . Is the following quite true: does the wrapper in numactl
+.\" do the right thing?
+On error, it returns \-1, and sets
+.I errno
+to indicate the error.
+If positive value is returned, it is the number of
+nonmigrated pages.
+.SH ERRORS
+.TP
+.B Positive value
+The number of nonmigrated pages if they were the result of nonfatal
+reasons (since
+.\" commit a49bd4d7163707de377aee062f17befef6da891b
+Linux 4.17).
+.TP
+.B E2BIG
+Too many pages to move.
+Since Linux 2.6.29,
+.\" commit 3140a2273009c01c27d316f35ab76a37e105fdd8
+the kernel no longer generates this error.
+.TP
+.B EACCES
+.\" FIXME Clarify "current cpuset" in the description of the EACCES error.
+.\" Is that the cpuset of the caller or the target?
+One of the target nodes is not allowed by the current cpuset.
+.TP
+.B EFAULT
+Parameter array could not be accessed.
+.TP
+.B EINVAL
+Flags other than
+.B MPOL_MF_MOVE
+and
+.B MPOL_MF_MOVE_ALL
+was specified or an attempt was made to migrate pages of a kernel thread.
+.TP
+.B ENODEV
+One of the target nodes is not online.
+.TP
+.B EPERM
+The caller specified
+.B MPOL_MF_MOVE_ALL
+without sufficient privileges
+.RB ( CAP_SYS_NICE ).
+Or, the caller attempted to move pages of a process belonging
+to another user but did not have privilege to do so
+.RB ( CAP_SYS_NICE ).
+.TP
+.B ESRCH
+Process does not exist.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.18.
+.SH NOTES
+For information on library support, see
+.BR numa (7).
+.P
+Use
+.BR get_mempolicy (2)
+with the
+.B MPOL_F_MEMS_ALLOWED
+flag to obtain the set of nodes that are allowed by
+.\" FIXME Clarify "current cpuset".  Is that the cpuset of the caller
+.\" or the target?
+the current cpuset.
+Note that this information is subject to change at any
+time by manual or automatic reconfiguration of the cpuset.
+.P
+Use of this function may result in pages whose location
+(node) violates the memory policy established for the
+specified addresses (See
+.BR mbind (2))
+and/or the specified process (See
+.BR set_mempolicy (2)).
+That is, memory policy does not constrain the destination
+nodes used by
+.BR move_pages ().
+.P
+The
+.I <numaif.h>
+header is not included with glibc, but requires installing
+.I libnuma\-devel
+or a similar package.
+.SH SEE ALSO
+.BR get_mempolicy (2),
+.BR mbind (2),
+.BR set_mempolicy (2),
+.BR numa (3),
+.BR numa_maps (5),
+.BR cpuset (7),
+.BR numa (7),
+.BR migratepages (8),
+.BR numastat (8)
diff --git a/man/man2/mprotect.2 b/man/man2/mprotect.2
new file mode 100644
index 000000000..63781f536
--- /dev/null
+++ b/man/man2/mprotect.2
@@ -0,0 +1,363 @@
+.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 1995 Michael Shields <shields@tembel.org>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1997-05-31 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2003-08-24 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2004-08-16 by Andi Kleen <ak@muc.de>
+.\" 2007-06-02, mtk: Fairly substantial rewrites and additions, and
+.\" a much improved example program.
+.\"
+.TH mprotect 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mprotect, pkey_mprotect \- set protection on a region of memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "int mprotect(void " addr [. len "], size_t " len ", int " prot );
+.P
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sys/mman.h>
+.P
+.BI "int pkey_mprotect(void " addr [. len "], size_t " len ", int " prot ", int " pkey ");"
+.fi
+.SH DESCRIPTION
+.BR mprotect ()
+changes the access protections for the calling process's memory pages
+containing any part of the address range in the
+interval [\fIaddr\fP,\ \fIaddr\fP+\fIlen\fP\-1].
+.I addr
+must be aligned to a page boundary.
+.P
+If the calling process tries to access memory in a manner
+that violates the protections, then the kernel generates a
+.B SIGSEGV
+signal for the process.
+.P
+.I prot
+is a combination of the following access flags:
+.B PROT_NONE
+or a bitwise OR of the other values in the following list:
+.TP
+.B PROT_NONE
+The memory cannot be accessed at all.
+.TP
+.B PROT_READ
+The memory can be read.
+.TP
+.B PROT_WRITE
+The memory can be modified.
+.TP
+.B PROT_EXEC
+The memory can be executed.
+.TP
+.BR PROT_SEM " (since Linux 2.5.7)"
+The memory can be used for atomic operations.
+This flag was introduced as part of the
+.BR futex (2)
+implementation (in order to guarantee the ability to perform atomic
+operations required by commands such as
+.BR FUTEX_WAIT ),
+but is not currently used in on any architecture.
+.TP
+.BR PROT_SAO " (since Linux 2.6.26)"
+.\" commit aba46c5027cb59d98052231b36efcbbde9c77a1d
+.\" commit ef3d3246a0d06be622867d21af25f997aeeb105f
+The memory should have strong access ordering.
+This feature is specific to
+the PowerPC architecture
+(version 2.06 of the architecture specification adds the SAO CPU feature,
+and it is available on POWER 7 or PowerPC A2, for example).
+.P
+Additionally (since Linux 2.6.0),
+.I prot
+can have one of the following flags set:
+.TP
+.\" mm/mmap.c:
+.\"	vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
+.\"			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+.\" And calc_vm_flag_bits converts only GROWSDOWN/DENYWRITE/LOCKED.
+.B PROT_GROWSUP
+Apply the protection mode up to the end of a mapping
+that grows upwards.
+(Such mappings are created for the stack area on
+architectures\[em]for example, HP-PARISC\[em]that
+have an upwardly growing stack.)
+.\" The VMA is one that was marked with VM_GROWSUP by the kernel
+.\" when the stack was created. Note that (unlike VM_GROWSDOWN),
+.\" there is no mmap() flag (analogous to MAP_GROWSDOWN) for
+.\" creating a VMA that is marked VM_GROWSUP.
+.TP
+.B PROT_GROWSDOWN
+Apply the protection mode down to the beginning of a mapping
+that grows downward
+(which should be a stack segment or a segment mapped with the
+.B MAP_GROWSDOWN
+flag set).
+.P
+Like
+.BR mprotect (),
+.BR pkey_mprotect ()
+changes the protection on the pages specified by
+.I addr
+and
+.IR len .
+The
+.I pkey
+argument specifies the protection key (see
+.BR pkeys (7))
+to assign to the memory.
+The protection key must be allocated with
+.BR pkey_alloc (2)
+before it is passed to
+.BR pkey_mprotect ().
+For an example of the use of this system call, see
+.BR pkeys (7).
+.SH RETURN VALUE
+On success,
+.BR mprotect ()
+and
+.BR pkey_mprotect ()
+return zero.
+On error, these system calls return \-1, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The memory cannot be given the specified access.
+This can happen, for example, if you
+.BR mmap (2)
+a file to which you have read-only access, then ask
+.BR mprotect ()
+to mark it
+.BR PROT_WRITE .
+.TP
+.B EINVAL
+\fIaddr\fP is not a valid pointer,
+or not a multiple of the system page size.
+.TP
+.B EINVAL
+.RB ( pkey_mprotect ())
+\fIpkey\fP has not been allocated with
+.BR pkey_alloc (2)
+.TP
+.B EINVAL
+Both
+.B PROT_GROWSUP
+and
+.B PROT_GROWSDOWN
+were specified in
+.IR prot .
+.TP
+.B EINVAL
+Invalid flags specified in
+.IR prot .
+.TP
+.B EINVAL
+(PowerPC architecture)
+.B PROT_SAO
+was specified in
+.IR prot ,
+but SAO hardware feature is not available.
+.TP
+.B ENOMEM
+Internal kernel structures could not be allocated.
+.TP
+.B ENOMEM
+Addresses in the range
+.RI [ addr ,
+.IR addr + len \-1]
+are invalid for the address space of the process,
+or specify one or more pages that are not mapped.
+(Before Linux 2.4.19, the error
+.B EFAULT
+was incorrectly produced for these cases.)
+.TP
+.B ENOMEM
+Changing the protection of a memory region would result in the total number of
+mappings with distinct attributes (e.g., read versus read/write protection)
+exceeding the allowed maximum.
+.\" I.e., the number of VMAs would exceed the 64 kB maximum
+(For example, making the protection of a range
+.B PROT_READ
+in the middle of a region currently protected as
+.B PROT_READ|PROT_WRITE
+would result in three mappings:
+two read/write mappings at each end and a read-only mapping in the middle.)
+.SH VERSIONS
+.\" SVr4 defines an additional error
+.\" code EAGAIN. The SVr4 error conditions don't map neatly onto Linux's.
+POSIX says that the behavior of
+.BR mprotect ()
+is unspecified if it is applied to a region of memory that
+was not obtained via
+.BR mmap (2).
+.P
+On Linux, it is always permissible to call
+.BR mprotect ()
+on any address in a process's address space (except for the
+kernel vsyscall area).
+In particular, it can be used
+to change existing code mappings to be writable.
+.P
+Whether
+.B PROT_EXEC
+has any effect different from
+.B PROT_READ
+depends on processor architecture, kernel version, and process state.
+If
+.B READ_IMPLIES_EXEC
+is set in the process's personality flags (see
+.BR personality (2)),
+specifying
+.B PROT_READ
+will implicitly add
+.BR PROT_EXEC .
+.P
+On some hardware architectures (e.g., i386),
+.B PROT_WRITE
+implies
+.BR PROT_READ .
+.P
+POSIX.1 says that an implementation may permit access
+other than that specified in
+.IR prot ,
+but at a minimum can allow write access only if
+.B PROT_WRITE
+has been set, and must not allow any access if
+.B PROT_NONE
+has been set.
+.P
+Applications should be careful when mixing use of
+.BR mprotect ()
+and
+.BR pkey_mprotect ().
+On x86, when
+.BR mprotect ()
+is used with
+.I prot
+set to
+.B PROT_EXEC
+a pkey may be allocated and set on the memory implicitly
+by the kernel, but only when the pkey was 0 previously.
+.P
+On systems that do not support protection keys in hardware,
+.BR pkey_mprotect ()
+may still be used, but
+.I pkey
+must be set to \-1.
+When called this way, the operation of
+.BR pkey_mprotect ()
+is equivalent to
+.BR mprotect ().
+.SH STANDARDS
+.TP
+.BR mprotect ()
+POSIX.1-2008.
+.TP
+.BR pkey_mprotect ()
+Linux.
+.SH HISTORY
+.TP
+.BR mprotect ()
+POSIX.1-2001, SVr4.
+.TP
+.BR pkey_mprotect ()
+Linux 4.9,
+glibc 2.27.
+.SH NOTES
+.SH EXAMPLES
+.\" sigaction.2 refers to this example
+The program below demonstrates the use of
+.BR mprotect ().
+The program allocates four pages of memory, makes the third
+of these pages read-only, and then executes a loop that walks upward
+through the allocated region modifying bytes.
+.P
+An example of what we might see when running the program is the
+following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+Start of region:        0x804c000
+Got SIGSEGV at address: 0x804e000
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (mprotect.c)
+.EX
+#include <malloc.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+\&
+#define handle_error(msg) \e
+    do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static char *buffer;
+\&
+static void
+handler(int sig, siginfo_t *si, void *unused)
+{
+    /* Note: calling printf() from a signal handler is not safe
+       (and should not be done in production programs), since
+       printf() is not async\-signal\-safe; see signal\-safety(7).
+       Nevertheless, we use printf() here as a simple way of
+       showing that the handler was called. */
+\&
+    printf("Got SIGSEGV at address: %p\en", si\->si_addr);
+    exit(EXIT_FAILURE);
+}
+\&
+int
+main(void)
+{
+    int               pagesize;
+    struct sigaction  sa;
+\&
+    sa.sa_flags = SA_SIGINFO;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_sigaction = handler;
+    if (sigaction(SIGSEGV, &sa, NULL) == \-1)
+        handle_error("sigaction");
+\&
+    pagesize = sysconf(_SC_PAGE_SIZE);
+    if (pagesize == \-1)
+        handle_error("sysconf");
+\&
+    /* Allocate a buffer aligned on a page boundary;
+       initial protection is PROT_READ | PROT_WRITE. */
+\&
+    buffer = memalign(pagesize, 4 * pagesize);
+    if (buffer == NULL)
+        handle_error("memalign");
+\&
+    printf("Start of region:        %p\en", buffer);
+\&
+    if (mprotect(buffer + pagesize * 2, pagesize,
+                 PROT_READ) == \-1)
+        handle_error("mprotect");
+\&
+    for (char *p = buffer ; ; )
+        *(p++) = \[aq]a\[aq];
+\&
+    printf("Loop completed\en");     /* Should never happen */
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR mmap (2),
+.BR sysconf (3),
+.BR pkeys (7)
diff --git a/man/man2/mpx.2 b/man/man2/mpx.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/mpx.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/mq_getsetattr.2 b/man/man2/mq_getsetattr.2
new file mode 100644
index 000000000..8f08436fd
--- /dev/null
+++ b/man/man2/mq_getsetattr.2
@@ -0,0 +1,33 @@
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_getsetattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_getsetattr \- get/set message queue attributes
+.SH SYNOPSIS
+.nf
+.BR "#include <mqueue.h>" "           /* Definition of " "struct mq_attr" " */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_mq_getsetattr, mqd_t " mqdes ,
+.BI "            const struct mq_attr *" newattr ", struct mq_attr *" oldattr );
+.fi
+.SH DESCRIPTION
+Do not use this system call.
+.P
+This is the low-level system call used to implement
+.BR mq_getattr (3)
+and
+.BR mq_setattr (3).
+For an explanation of how this system call operates,
+see the description of
+.BR mq_setattr (3).
+.SH STANDARDS
+None.
+.SH NOTES
+Never call it unless you are writing a C library!
+.SH SEE ALSO
+.BR mq_getattr (3),
+.BR mq_overview (7)
diff --git a/man/man2/mq_notify.2 b/man/man2/mq_notify.2
new file mode 100644
index 000000000..505a45e2e
--- /dev/null
+++ b/man/man2/mq_notify.2
@@ -0,0 +1,2 @@
+.so man3/mq_notify.3
+.\" Because mq_notify(3) is layered on a system call of the same name
diff --git a/man/man2/mq_open.2 b/man/man2/mq_open.2
new file mode 100644
index 000000000..ce82835e6
--- /dev/null
+++ b/man/man2/mq_open.2
@@ -0,0 +1,2 @@
+.so man3/mq_open.3
+.\" Because mq_open(3) is layered on a system call of the same name
diff --git a/man/man2/mq_timedreceive.2 b/man/man2/mq_timedreceive.2
new file mode 100644
index 000000000..b4184f8c2
--- /dev/null
+++ b/man/man2/mq_timedreceive.2
@@ -0,0 +1,2 @@
+.so man3/mq_timedreceive.3
+.\" Because mq_timedreceive(3) is layered on a system call of the same name
diff --git a/man/man2/mq_timedsend.2 b/man/man2/mq_timedsend.2
new file mode 100644
index 000000000..db95863ad
--- /dev/null
+++ b/man/man2/mq_timedsend.2
@@ -0,0 +1,2 @@
+.so man3/mq_timedsend.3
+.\" Because mq_timedsend(3) is layered on a system call of the same name
diff --git a/man/man2/mq_unlink.2 b/man/man2/mq_unlink.2
new file mode 100644
index 000000000..c5f276826
--- /dev/null
+++ b/man/man2/mq_unlink.2
@@ -0,0 +1,2 @@
+.so man3/mq_unlink.3
+.\" Because mq_unlink(3) is layered on a system call of the same name
diff --git a/man/man2/mremap.2 b/man/man2/mremap.2
new file mode 100644
index 000000000..336aae676
--- /dev/null
+++ b/man/man2/mremap.2
@@ -0,0 +1,357 @@
+.\" Copyright (c) 1996 Tom Bjorkholm <tomb@mydata.se>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1996-04-11 Tom Bjorkholm <tomb@mydata.se>
+.\"            First version written (1.3.86)
+.\" 1996-04-12 Tom Bjorkholm <tomb@mydata.se>
+.\"            Update for Linux 1.3.87 and later
+.\" 2005-10-11 mtk: Added NOTES for MREMAP_FIXED; revised EINVAL text.
+.\"
+.TH mremap 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mremap \- remap a virtual memory address
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <sys/mman.h>
+.P
+.BI "void *mremap(void " old_address [. old_size "], size_t " old_size ,
+.BI "             size_t " new_size ", int " flags ", ... /* void *" new_address " */);"
+.fi
+.SH DESCRIPTION
+.BR mremap ()
+expands (or shrinks) an existing memory mapping, potentially
+moving it at the same time (controlled by the \fIflags\fP argument and
+the available virtual address space).
+.P
+\fIold_address\fP is the old address of the virtual memory block that you
+want to expand (or shrink).
+Note that \fIold_address\fP has to be page
+aligned.
+\fIold_size\fP is the old size of the
+virtual memory block.
+\fInew_size\fP is the requested size of the
+virtual memory block after the resize.
+An optional fifth argument,
+.IR new_address ,
+may be provided; see the description of
+.B MREMAP_FIXED
+below.
+.P
+If the value of \fIold_size\fP is zero, and \fIold_address\fP refers to
+a shareable mapping
+(see the description of
+.B MAP_SHARED
+in
+.BR mmap (2)),
+then
+.BR mremap ()
+will create a new mapping of the same pages.
+\fInew_size\fP
+will be the size of the new mapping and the location of the new mapping
+may be specified with \fInew_address\fP; see the description of
+.B MREMAP_FIXED
+below.
+If a new mapping is requested via this method, then the
+.B MREMAP_MAYMOVE
+flag must also be specified.
+.P
+The \fIflags\fP bit-mask argument may be 0, or include the following flags:
+.TP
+.B MREMAP_MAYMOVE
+By default, if there is not sufficient space to expand a mapping
+at its current location, then
+.BR mremap ()
+fails.
+If this flag is specified, then the kernel is permitted to
+relocate the mapping to a new virtual address, if necessary.
+If the mapping is relocated,
+then absolute pointers into the old mapping location
+become invalid (offsets relative to the starting address of
+the mapping should be employed).
+.TP
+.BR MREMAP_FIXED " (since Linux 2.3.31)"
+This flag serves a similar purpose to the
+.B MAP_FIXED
+flag of
+.BR mmap (2).
+If this flag is specified, then
+.BR mremap ()
+accepts a fifth argument,
+.IR "void\ *new_address" ,
+which specifies a page-aligned address to which the mapping must
+be moved.
+Any previous mapping at the address range specified by
+.I new_address
+and
+.I new_size
+is unmapped.
+.IP
+If
+.B MREMAP_FIXED
+is specified, then
+.B MREMAP_MAYMOVE
+must also be specified.
+.TP
+.BR MREMAP_DONTUNMAP " (since Linux 5.7)"
+.\" commit e346b3813067d4b17383f975f197a9aa28a3b077
+This flag, which must be used in conjunction with
+.BR MREMAP_MAYMOVE ,
+remaps a mapping to a new address but does not unmap the mapping at
+.IR old_address .
+.IP
+The
+.B MREMAP_DONTUNMAP
+flag can be used only with private anonymous mappings
+(see the description of
+.B MAP_PRIVATE
+and
+.B MAP_ANONYMOUS
+in
+.BR mmap (2)).
+.IP
+After completion,
+any access to the range specified by
+.I old_address
+and
+.I old_size
+will result in a page fault.
+The page fault will be handled by a
+.BR userfaultfd (2)
+handler
+if the address is in a range previously registered with
+.BR userfaultfd (2).
+Otherwise, the kernel allocates a zero-filled page to handle the fault.
+.IP
+The
+.B MREMAP_DONTUNMAP
+flag may be used to atomically move a mapping while leaving the source
+mapped.
+See NOTES for some possible applications of
+.BR MREMAP_DONTUNMAP .
+.P
+If the memory segment specified by
+.I old_address
+and
+.I old_size
+is locked (using
+.BR mlock (2)
+or similar), then this lock is maintained when the segment is
+resized and/or relocated.
+As a consequence, the amount of memory locked by the process may change.
+.SH RETURN VALUE
+On success
+.BR mremap ()
+returns a pointer to the new virtual memory area.
+On error, the value
+.B MAP_FAILED
+(that is, \fI(void\ *)\ \-1\fP) is returned,
+and \fIerrno\fP is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The caller tried to expand a memory segment that is locked,
+but this was not possible without exceeding the
+.B RLIMIT_MEMLOCK
+resource limit.
+.TP
+.B EFAULT
+Some address in the range
+\fIold_address\fP to \fIold_address\fP+\fIold_size\fP is an invalid
+virtual memory address for this process.
+You can also get
+.B EFAULT
+even if there exist mappings that cover the
+whole address space requested, but those mappings are of different types.
+.TP
+.B EINVAL
+An invalid argument was given.
+Possible causes are:
+.RS
+.IP \[bu] 3
+\fIold_address\fP was not
+page aligned;
+.IP \[bu]
+a value other than
+.B MREMAP_MAYMOVE
+or
+.B MREMAP_FIXED
+or
+.B MREMAP_DONTUNMAP
+was specified in
+.IR flags ;
+.IP \[bu]
+.I new_size
+was zero;
+.IP \[bu]
+.I new_size
+or
+.I new_address
+was invalid;
+.IP \[bu]
+the new address range specified by
+.I new_address
+and
+.I new_size
+overlapped the old address range specified by
+.I old_address
+and
+.IR old_size ;
+.IP \[bu]
+.B MREMAP_FIXED
+or
+.B MREMAP_DONTUNMAP
+was specified without also specifying
+.BR MREMAP_MAYMOVE ;
+.IP \[bu]
+.B MREMAP_DONTUNMAP
+was specified, but one or more pages in the range specified by
+.I old_address
+and
+.I old_size
+were not private anonymous;
+.IP \[bu]
+.B MREMAP_DONTUNMAP
+was specified and
+.I old_size
+was not equal to
+.IR new_size ;
+.IP \[bu]
+\fIold_size\fP was zero and \fIold_address\fP does not refer to a
+shareable mapping (but see BUGS);
+.IP \[bu]
+\fIold_size\fP was zero and the
+.B MREMAP_MAYMOVE
+flag was not specified.
+.RE
+.TP
+.B ENOMEM
+Not enough memory was available to complete the operation.
+Possible causes are:
+.RS
+.IP \[bu] 3
+The memory area cannot be expanded at the current virtual address, and the
+.B MREMAP_MAYMOVE
+flag is not set in \fIflags\fP.
+Or, there is not enough (virtual) memory available.
+.IP \[bu]
+.B MREMAP_DONTUNMAP
+was used causing a new mapping to be created that would exceed the
+(virtual) memory available.
+Or, it would exceed the maximum number of allowed mappings.
+.RE
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.\" 4.2BSD had a (never actually implemented)
+.\" .BR mremap (2)
+.\" call with completely different semantics.
+.\" .P
+Prior to glibc 2.4, glibc did not expose the definition of
+.BR MREMAP_FIXED ,
+and the prototype for
+.BR mremap ()
+did not allow for the
+.I new_address
+argument.
+.SH NOTES
+.BR mremap ()
+changes the
+mapping between virtual addresses and memory pages.
+This can be used to implement a very efficient
+.BR realloc (3).
+.P
+In Linux, memory is divided into pages.
+A process has (one or)
+several linear virtual memory segments.
+Each virtual memory segment has one
+or more mappings to real memory pages (in the page table).
+Each virtual memory segment has its own
+protection (access rights), which may cause
+a segmentation violation
+.RB ( SIGSEGV )
+if the memory is accessed incorrectly (e.g.,
+writing to a read-only segment).
+Accessing virtual memory outside of the
+segments will also cause a segmentation violation.
+.P
+If
+.BR mremap ()
+is used to move or expand an area locked with
+.BR mlock (2)
+or equivalent, the
+.BR mremap ()
+call will make a best effort to populate the new area but will not fail
+with
+.B ENOMEM
+if the area cannot be populated.
+.\"
+.SS MREMAP_DONTUNMAP use cases
+Possible applications for
+.B MREMAP_DONTUNMAP
+include:
+.IP \[bu] 3
+Non-cooperative
+.BR userfaultfd (2):
+an application can yank out a virtual address range using
+.B MREMAP_DONTUNMAP
+and then employ a
+.BR userfaultfd (2)
+handler to handle the page faults that subsequently occur
+as other threads in the process touch pages in the yanked range.
+.IP \[bu]
+Garbage collection:
+.B MREMAP_DONTUNMAP
+can be used in conjunction with
+.BR userfaultfd (2)
+to implement garbage collection algorithms (e.g., in a Java virtual machine).
+Such an implementation can be cheaper (and simpler)
+than conventional garbage collection techniques that involve
+marking pages with protection
+.B PROT_NONE
+in conjunction with the use of a
+.B SIGSEGV
+handler to catch accesses to those pages.
+.SH BUGS
+Before Linux 4.14,
+if
+.I old_size
+was zero and the mapping referred to by
+.I old_address
+was a private mapping
+(see the description of
+.B MAP_PRIVATE
+in
+.BR mmap (2)),
+.BR mremap ()
+created a new private mapping unrelated to the original mapping.
+This behavior was unintended
+and probably unexpected in user-space applications
+(since the intention of
+.BR mremap ()
+is to create a new mapping based on the original mapping).
+Since Linux 4.14,
+.\" commit dba58d3b8c5045ad89c1c95d33d01451e3964db7
+.BR mremap ()
+fails with the error
+.B EINVAL
+in this scenario.
+.SH SEE ALSO
+.BR brk (2),
+.BR getpagesize (2),
+.BR getrlimit (2),
+.BR mlock (2),
+.BR mmap (2),
+.BR sbrk (2),
+.BR malloc (3),
+.BR realloc (3)
+.P
+Your favorite text book on operating systems
+for more information on paged memory
+(e.g., \fIModern Operating Systems\fP by Andrew S.\& Tanenbaum,
+\fIInside Linux\fP by Randolph Bentson,
+\fIThe Design of the UNIX Operating System\fP by Maurice J.\& Bach)
diff --git a/man/man2/msgctl.2 b/man/man2/msgctl.2
new file mode 100644
index 000000000..70f4d1cf8
--- /dev/null
+++ b/man/man2/msgctl.2
@@ -0,0 +1,424 @@
+'\" t
+.\" Copyright 1993 Giorgio Ciucci (giorgio@crcc.it)
+.\" and Copyright 2004, 2005 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Sun Feb 18 01:59:29 2001 by Andries E. Brouwer <aeb@cwi.nl>
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on CAP_IPC_OWNER requirement
+.\" Modified, 17 Jun 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on CAP_SYS_ADMIN requirement for IPC_SET and IPC_RMID
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Added msqid_ds and ipc_perm structure definitions
+.\" 2005-08-02, mtk: Added IPC_INFO, MSG_INFO, MSG_STAT descriptions
+.\" 2018-03-20, dbueso: Added MSG_STAT_ANY description.
+.\"
+.TH msgctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+msgctl \- System V message control operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/msg.h>
+.P
+.BI "int msgctl(int " msqid ", int " op ", struct msqid_ds *" buf );
+.fi
+.SH DESCRIPTION
+.BR msgctl ()
+performs the control operation specified by
+.I op
+on the System\ V message queue with identifier
+.IR msqid .
+.P
+The
+.I msqid_ds
+data structure is defined in \fI<sys/msg.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct msqid_ds {
+    struct ipc_perm msg_perm;   /* Ownership and permissions */
+    time_t          msg_stime;  /* Time of last msgsnd(2) */
+    time_t          msg_rtime;  /* Time of last msgrcv(2) */
+    time_t          msg_ctime;  /* Time of creation or last
+                                   modification by msgctl() */
+    unsigned long   msg_cbytes; /* # of bytes in queue */
+    msgqnum_t       msg_qnum;   /* # number of messages in queue */
+    msglen_t        msg_qbytes; /* Maximum # of bytes in queue */
+    pid_t           msg_lspid;  /* PID of last msgsnd(2) */
+    pid_t           msg_lrpid;  /* PID of last msgrcv(2) */
+};
+.EE
+.in
+.P
+The fields of the
+.I msqid_ds
+structure are as follows:
+.TP 11
+.I msg_perm
+This is an
+.I ipc_perm
+structure (see below) that specifies the access permissions on the message
+queue.
+.TP
+.I msg_stime
+Time of the last
+.BR msgsnd (2)
+system call.
+.TP
+.I msg_rtime
+Time of the last
+.BR msgrcv (2)
+system call.
+.TP
+.I msg_ctime
+Time of creation of queue or time of last
+.BR msgctl ()
+.B IPC_SET
+operation.
+.TP
+.I msg_cbytes
+Number of bytes in all messages currently on the message queue.
+This is a nonstandard Linux extension that is not specified in POSIX.
+.TP
+.I msg_qnum
+Number of messages currently on the message queue.
+.TP
+.I msg_qbytes
+Maximum number of bytes of message text allowed on the message
+queue.
+.TP
+.I msg_lspid
+ID of the process that performed the last
+.BR msgsnd (2)
+system call.
+.TP
+.I msg_lrpid
+ID of the process that performed the last
+.BR msgrcv (2)
+system call.
+.P
+The
+.I ipc_perm
+structure is defined as follows
+(the highlighted fields are settable using
+.BR IPC_SET ):
+.P
+.in +4n
+.EX
+struct ipc_perm {
+    key_t          __key;       /* Key supplied to msgget(2) */
+    uid_t          \fBuid\fP;         /* Effective UID of owner */
+    gid_t          \fBgid\fP;         /* Effective GID of owner */
+    uid_t          cuid;        /* Effective UID of creator */
+    gid_t          cgid;        /* Effective GID of creator */
+    unsigned short \fBmode\fP;        /* Permissions */
+    unsigned short __seq;       /* Sequence number */
+};
+.EE
+.in
+.P
+The least significant 9 bits of the
+.I mode
+field of the
+.I ipc_perm
+structure define the access permissions for the message queue.
+The permission bits are as follows:
+.TS
+l l.
+0400	Read by user
+0200	Write by user
+0040	Read by group
+0020	Write by group
+0004	Read by others
+0002	Write by others
+.TE
+.P
+Bits 0100, 0010, and 0001 (the execute bits) are unused by the system.
+.P
+Valid values for
+.I op
+are:
+.TP
+.B IPC_STAT
+Copy information from the kernel data structure associated with
+.I msqid
+into the
+.I msqid_ds
+structure pointed to by
+.IR buf .
+The caller must have read permission on the message queue.
+.TP
+.B IPC_SET
+Write the values of some members of the
+.I msqid_ds
+structure pointed to by
+.I buf
+to the kernel data structure associated with this message queue,
+updating also its
+.I msg_ctime
+member.
+.IP
+The following members of the structure are updated:
+.IR msg_qbytes ,
+.IR msg_perm.uid ,
+.IR msg_perm.gid ,
+and (the least significant 9 bits of)
+.IR msg_perm.mode .
+.IP
+The effective UID of the calling process must match the owner
+.RI ( msg_perm.uid )
+or creator
+.RI ( msg_perm.cuid )
+of the message queue, or the caller must be privileged.
+Appropriate privilege (Linux: the
+.B CAP_SYS_RESOURCE
+capability) is required to raise the
+.I msg_qbytes
+value beyond the system parameter
+.BR MSGMNB .
+.TP
+.B IPC_RMID
+Immediately remove the message queue,
+awakening all waiting reader and writer processes (with an error
+return and
+.I errno
+set to
+.BR EIDRM ).
+The calling process must have appropriate privileges
+or its effective user ID must be either that of the creator or owner
+of the message queue.
+The third argument to
+.BR msgctl ()
+is ignored in this case.
+.TP
+.BR IPC_INFO " (Linux-specific)"
+Return information about system-wide message queue limits and
+parameters in the structure pointed to by
+.IR buf .
+This structure is of type
+.I msginfo
+(thus, a cast is required),
+defined in
+.I <sys/msg.h>
+if the
+.B _GNU_SOURCE
+feature test macro is defined:
+.IP
+.in +4n
+.EX
+struct msginfo {
+    int msgpool; /* Size in kibibytes of buffer pool
+                    used to hold message data;
+                    unused within kernel */
+    int msgmap;  /* Maximum number of entries in message
+                    map; unused within kernel */
+    int msgmax;  /* Maximum number of bytes that can be
+                    written in a single message */
+    int msgmnb;  /* Maximum number of bytes that can be
+                    written to queue; used to initialize
+                    msg_qbytes during queue creation
+                    (msgget(2)) */
+    int msgmni;  /* Maximum number of message queues */
+    int msgssz;  /* Message segment size;
+                    unused within kernel */
+    int msgtql;  /* Maximum number of messages on all queues
+                    in system; unused within kernel */
+    unsigned short msgseg;
+                 /* Maximum number of segments;
+                    unused within kernel */
+};
+.EE
+.in
+.IP
+The
+.IR msgmni ,
+.IR msgmax ,
+and
+.I msgmnb
+settings can be changed via
+.I /proc
+files of the same name; see
+.BR proc (5)
+for details.
+.TP
+.BR MSG_INFO " (Linux-specific)"
+Return a
+.I msginfo
+structure containing the same information as for
+.BR IPC_INFO ,
+except that the following fields are returned with information
+about system resources consumed by message queues: the
+.I msgpool
+field returns the number of message queues that currently exist
+on the system; the
+.I msgmap
+field returns the total number of messages in all queues
+on the system; and the
+.I msgtql
+field returns the total number of bytes in all messages
+in all queues on the system.
+.TP
+.BR MSG_STAT " (Linux-specific)"
+Return a
+.I msqid_ds
+structure as for
+.BR IPC_STAT .
+However, the
+.I msqid
+argument is not a queue identifier, but instead an index into
+the kernel's internal array that maintains information about
+all message queues on the system.
+.TP
+.BR MSG_STAT_ANY " (Linux-specific, since Linux 4.17)"
+Return a
+.I msqid_ds
+structure as for
+.BR MSG_STAT .
+However,
+.I msg_perm.mode
+is not checked for read access for
+.I msqid
+meaning that any user can employ this operation (just as any user may read
+.I /proc/sysvipc/msg
+to obtain the same information).
+.SH RETURN VALUE
+On success,
+.BR IPC_STAT ,
+.BR IPC_SET ,
+and
+.B IPC_RMID
+return 0.
+A successful
+.B IPC_INFO
+or
+.B MSG_INFO
+operation returns the index of the highest used entry in the
+kernel's internal array recording information about all
+message queues.
+(This information can be used with repeated
+.B MSG_STAT
+or
+.B MSG_STAT_ANY
+operations to obtain information about all queues on the system.)
+A successful
+.B MSG_STAT
+or
+.B MSG_STAT_ANY
+operation returns the identifier of the queue whose index was given in
+.IR msqid .
+.P
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The argument
+.I op
+is equal to
+.B IPC_STAT
+or
+.BR MSG_STAT ,
+but the calling process does not have read permission on the message queue
+.IR msqid ,
+and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EFAULT
+The argument
+.I op
+has the value
+.B IPC_SET
+or
+.BR IPC_STAT ,
+but the address pointed to by
+.I buf
+isn't accessible.
+.TP
+.B EIDRM
+The message queue was removed.
+.TP
+.B EINVAL
+Invalid value for
+.I op
+or
+.IR msqid .
+Or: for a
+.B MSG_STAT
+operation, the index value specified in
+.I msqid
+referred to an array slot that is currently unused.
+.TP
+.B EPERM
+The argument
+.I op
+has the value
+.B IPC_SET
+or
+.BR IPC_RMID ,
+but the effective user ID of the calling process is not the creator
+(as found in
+.IR msg_perm.cuid )
+or the owner
+(as found in
+.IR msg_perm.uid )
+of the message queue,
+and the caller is not privileged (Linux: does not have the
+.B CAP_SYS_ADMIN
+capability).
+.TP
+.B EPERM
+An attempt
+.RB ( IPC_SET )
+was made to increase
+.I msg_qbytes
+beyond the system parameter
+.BR MSGMNB ,
+but the caller is not privileged (Linux: does not have the
+.B CAP_SYS_RESOURCE
+capability).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.\" SVID does not document the EIDRM error condition.
+.P
+Various fields in the \fIstruct msqid_ds\fP were
+typed as
+.I short
+under Linux 2.2
+and have become
+.I long
+under Linux 2.4.
+To take advantage of this,
+a recompilation under glibc-2.1.91 or later should suffice.
+(The kernel distinguishes old and new calls by an
+.B IPC_64
+flag in
+.IR op .)
+.SH NOTES
+The
+.BR IPC_INFO ,
+.BR MSG_STAT ,
+and
+.B MSG_INFO
+operations are used by the
+.BR ipcs (1)
+program to provide information on allocated resources.
+In the future these may modified or moved to a
+.I /proc
+filesystem interface.
+.SH SEE ALSO
+.BR msgget (2),
+.BR msgrcv (2),
+.BR msgsnd (2),
+.BR capabilities (7),
+.BR mq_overview (7),
+.BR sysvipc (7)
diff --git a/man/man2/msgget.2 b/man/man2/msgget.2
new file mode 100644
index 000000000..b7105e7f5
--- /dev/null
+++ b/man/man2/msgget.2
@@ -0,0 +1,217 @@
+.\" Copyright 1993 Giorgio Ciucci <giorgio@crcc.it>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Added correction due to Nick Duffek <nsd@bbc.com>, aeb, 960426
+.\" Modified Wed Nov  6 04:00:31 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified, 8 Jan 2003, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"	Removed EIDRM from errors - that can't happen...
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Added notes on /proc files
+.\"
+.TH msgget 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+msgget \- get a System V message queue identifier
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/msg.h>
+.P
+.BI "int msgget(key_t " key ", int " msgflg );
+.fi
+.SH DESCRIPTION
+The
+.BR msgget ()
+system call returns the System\ V message queue identifier associated
+with the value of the
+.I key
+argument.
+It may be used either to obtain the identifier of a previously created
+message queue (when
+.I msgflg
+is zero and
+.I key
+does not have the value
+.BR IPC_PRIVATE ),
+or to create a new set.
+.P
+A new message queue is created if
+.I key
+has the value
+.B IPC_PRIVATE
+or
+.I key
+isn't
+.BR IPC_PRIVATE ,
+no message queue with the given key
+.I key
+exists, and
+.B IPC_CREAT
+is specified in
+.IR msgflg .
+.P
+If
+.I msgflg
+specifies both
+.B IPC_CREAT
+and
+.B IPC_EXCL
+and a message queue already exists for
+.IR key ,
+then
+.BR msgget ()
+fails with
+.I errno
+set to
+.BR EEXIST .
+(This is analogous to the effect of the combination
+.B O_CREAT | O_EXCL
+for
+.BR open (2).)
+.P
+Upon creation, the least significant bits of the argument
+.I msgflg
+define the permissions of the message queue.
+These permission bits have the same format and semantics
+as the permissions specified for the
+.I mode
+argument of
+.BR open (2).
+(The execute permissions are not used.)
+.P
+If a new message queue is created,
+then its associated data structure
+.I msqid_ds
+(see
+.BR msgctl (2))
+is initialized as follows:
+.IP \[bu] 3
+.I msg_perm.cuid
+and
+.I msg_perm.uid
+are set to the effective user ID of the calling process.
+.IP \[bu]
+.I msg_perm.cgid
+and
+.I msg_perm.gid
+are set to the effective group ID of the calling process.
+.IP \[bu]
+The least significant 9 bits of
+.I msg_perm.mode
+are set to the least significant 9 bits of
+.IR msgflg .
+.IP \[bu]
+.IR msg_qnum ,
+.IR msg_lspid ,
+.IR msg_lrpid ,
+.IR msg_stime ,
+and
+.I msg_rtime
+are set to 0.
+.IP \[bu]
+.I msg_ctime
+is set to the current time.
+.IP \[bu]
+.I msg_qbytes
+is set to the system limit
+.BR MSGMNB .
+.P
+If the message queue already exists the permissions are
+verified, and a check is made to see if it is marked for
+destruction.
+.SH RETURN VALUE
+On success,
+.BR msgget ()
+returns the message queue identifier (a nonnegative integer).
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+A message queue exists for
+.IR key ,
+but the calling process does not have permission to access the queue,
+and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EEXIST
+.B IPC_CREAT
+and
+.B IPC_EXCL
+were specified in
+.IR msgflg ,
+but a message queue already exists for
+.IR key .
+.TP
+.B ENOENT
+No message queue exists for
+.I key
+and
+.I msgflg
+did not specify
+.BR IPC_CREAT .
+.TP
+.B ENOMEM
+A message queue has to be created but the system does not have enough
+memory for the new data structure.
+.TP
+.B ENOSPC
+A message queue has to be created but the system limit for the maximum
+number of message queues
+.RB ( MSGMNI )
+would be exceeded.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.SS Linux
+Until Linux 2.3.20, Linux would return
+.B EIDRM
+for a
+.BR msgget ()
+on a message queue scheduled for deletion.
+.SH NOTES
+.B IPC_PRIVATE
+isn't a flag field but a
+.I key_t
+type.
+If this special value is used for
+.IR key ,
+the system call ignores everything but the least significant 9 bits of
+.I msgflg
+and creates a new message queue (on success).
+.P
+The following is a system limit on message queue resources affecting a
+.BR msgget ()
+call:
+.TP
+.B MSGMNI
+System-wide limit on the number of message queues.
+Before Linux 3.19,
+.\" commit 0050ee059f7fc86b1df2527aaa14ed5dc72f9973
+the default value for this limit was calculated using a formula
+based on available system memory.
+Since Linux 3.19, the default value is 32,000.
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/msgmni .
+.SH BUGS
+The name choice
+.B IPC_PRIVATE
+was perhaps unfortunate,
+.B IPC_NEW
+would more clearly show its function.
+.SH SEE ALSO
+.BR msgctl (2),
+.BR msgrcv (2),
+.BR msgsnd (2),
+.BR ftok (3),
+.BR capabilities (7),
+.BR mq_overview (7),
+.BR sysvipc (7)
diff --git a/man/man2/msgop.2 b/man/man2/msgop.2
new file mode 100644
index 000000000..6ffd76b2f
--- /dev/null
+++ b/man/man2/msgop.2
@@ -0,0 +1,684 @@
+.\" Copyright 1993 Giorgio Ciucci <giorgio@crcc.it>
+.\" and Copyright 2015 Bill Pemberton <wfp5p@worldbroken.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Tue Oct 22 16:40:11 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Mon Jul 10 21:09:59 2000 by aeb
+.\" Modified 1 Jun 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language clean-ups.
+.\"	Enhanced and corrected information on msg_qbytes, MSGMNB and MSGMAX
+.\"	Added note on restart behavior of msgsnd() and msgrcv()
+.\"	Formatting clean-ups (argument and field names marked as .I
+.\"		instead of .B)
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Added notes on /proc files
+.\"
+.TH MSGOP 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+msgrcv, msgsnd \- System V message queue operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/msg.h>
+.P
+.BI "int msgsnd(int " msqid ", const void " msgp [. msgsz "], size_t " msgsz ,
+.BI "               int " msgflg );
+.P
+.BI "ssize_t msgrcv(int " msqid ", void " msgp [. msgsz "], size_t " msgsz \
+", long " msgtyp ,
+.BI "               int " msgflg );
+.fi
+.SH DESCRIPTION
+The
+.BR msgsnd ()
+and
+.BR msgrcv ()
+system calls are used to send messages to,
+and receive messages from, a System\ V message queue.
+The calling process must have write permission on the message queue
+in order to send a message, and read permission to receive a message.
+.P
+The
+.I msgp
+argument is a pointer to a caller-defined structure
+of the following general form:
+.P
+.in +4n
+.EX
+struct msgbuf {
+    long mtype;       /* message type, must be > 0 */
+    char mtext[1];    /* message data */
+};
+.EE
+.in
+.P
+The
+.I mtext
+field is an array (or other structure) whose size is specified by
+.IR msgsz ,
+a nonnegative integer value.
+Messages of zero length (i.e., no
+.I mtext
+field) are permitted.
+The
+.I mtype
+field must have a strictly positive integer value.
+This value can be
+used by the receiving process for message selection
+(see the description of
+.BR msgrcv ()
+below).
+.SS msgsnd()
+The
+.BR msgsnd ()
+system call appends a copy of the message pointed to by
+.I msgp
+to the message queue whose identifier is specified
+by
+.IR msqid .
+.P
+If sufficient space is available in the queue,
+.BR msgsnd ()
+succeeds immediately.
+The queue capacity is governed by the
+.I msg_qbytes
+field in the associated data structure for the message queue.
+During queue creation this field is initialized to
+.B MSGMNB
+bytes, but this limit can be modified using
+.BR msgctl (2).
+A message queue is considered to be full if either of the following
+conditions is true:
+.IP \[bu] 3
+Adding a new message to the queue would cause the total number of bytes
+in the queue to exceed the queue's maximum size (the
+.I msg_qbytes
+field).
+.IP \[bu]
+Adding another message to the queue would cause the total number of messages
+in the queue to exceed the queue's maximum size (the
+.I msg_qbytes
+field).
+This check is necessary to prevent an unlimited number of zero-length
+messages being placed on the queue.
+Although such messages contain no data,
+they nevertheless consume (locked) kernel memory.
+.P
+If insufficient space is available in the queue, then the default
+behavior of
+.BR msgsnd ()
+is to block until space becomes available.
+If
+.B IPC_NOWAIT
+is specified in
+.IR msgflg ,
+then the call instead fails with the error
+.BR EAGAIN .
+.P
+A blocked
+.BR msgsnd ()
+call may also fail if:
+.IP \[bu] 3
+the queue is removed,
+in which case the system call fails with
+.I errno
+set to
+.BR EIDRM ;
+or
+.IP \[bu]
+a signal is caught, in which case the system call fails
+with
+.I errno
+set to
+.BR EINTR ; see
+.BR signal (7).
+.RB ( msgsnd ()
+is never automatically restarted after being interrupted by a
+signal handler, regardless of the setting of the
+.B SA_RESTART
+flag when establishing a signal handler.)
+.P
+Upon successful completion the message queue data structure is updated
+as follows:
+.IP \[bu] 3
+.I msg_lspid
+is set to the process ID of the calling process.
+.IP \[bu]
+.I msg_qnum
+is incremented by 1.
+.IP \[bu]
+.I msg_stime
+is set to the current time.
+.SS msgrcv()
+The
+.BR msgrcv ()
+system call removes a message from the queue specified by
+.I msqid
+and places it in the buffer
+pointed to by
+.IR msgp .
+.P
+The argument
+.I msgsz
+specifies the maximum size in bytes for the member
+.I mtext
+of the structure pointed to by the
+.I msgp
+argument.
+If the message text has length greater than
+.IR msgsz ,
+then the behavior depends on whether
+.B MSG_NOERROR
+is specified in
+.IR msgflg .
+If
+.B MSG_NOERROR
+is specified, then
+the message text will be truncated (and the truncated part will be
+lost); if
+.B MSG_NOERROR
+is not specified, then
+the message isn't removed from the queue and
+the system call fails returning \-1 with
+.I errno
+set to
+.BR E2BIG .
+.P
+Unless
+.B MSG_COPY
+is specified in
+.I msgflg
+(see below),
+the
+.I msgtyp
+argument specifies the type of message requested, as follows:
+.IP \[bu] 3
+If
+.I msgtyp
+is 0,
+then the first message in the queue is read.
+.IP \[bu]
+If
+.I msgtyp
+is greater than 0,
+then the first message in the queue of type
+.I msgtyp
+is read, unless
+.B MSG_EXCEPT
+was specified in
+.IR msgflg ,
+in which case
+the first message in the queue of type not equal to
+.I msgtyp
+will be read.
+.IP \[bu]
+If
+.I msgtyp
+is less than 0,
+then the first message in the queue with the lowest type less than or
+equal to the absolute value of
+.I msgtyp
+will be read.
+.P
+The
+.I msgflg
+argument is a bit mask constructed by ORing together zero or more
+of the following flags:
+.TP
+.B IPC_NOWAIT
+Return immediately if no message of the requested type is in the queue.
+The system call fails with
+.I errno
+set to
+.BR ENOMSG .
+.TP
+.BR MSG_COPY " (since Linux 3.8)"
+.\" commit 4a674f34ba04a002244edaf891b5da7fc1473ae8
+Nondestructively fetch a copy of the message at the ordinal position
+in the queue specified by
+.I msgtyp
+(messages are considered to be numbered starting at 0).
+.IP
+This flag must be specified in conjunction with
+.BR IPC_NOWAIT ,
+with the result that, if there is no message available at the given position,
+the call fails immediately with the error
+.BR ENOMSG .
+Because they alter the meaning of
+.I msgtyp
+in orthogonal ways,
+.B MSG_COPY
+and
+.B MSG_EXCEPT
+may not both be specified in
+.IR msgflg .
+.IP
+The
+.B MSG_COPY
+flag was added for the implementation of
+the kernel checkpoint-restore facility and
+is available only if the kernel was built with the
+.B CONFIG_CHECKPOINT_RESTORE
+option.
+.TP
+.B MSG_EXCEPT
+Used with
+.I msgtyp
+greater than 0
+to read the first message in the queue with message type that differs
+from
+.IR msgtyp .
+.TP
+.B MSG_NOERROR
+To truncate the message text if longer than
+.I msgsz
+bytes.
+.P
+If no message of the requested type is available and
+.B IPC_NOWAIT
+isn't specified in
+.IR msgflg ,
+the calling process is blocked until one of the following conditions occurs:
+.IP \[bu] 3
+A message of the desired type is placed in the queue.
+.IP \[bu]
+The message queue is removed from the system.
+In this case, the system call fails with
+.I errno
+set to
+.BR EIDRM .
+.IP \[bu]
+The calling process catches a signal.
+In this case, the system call fails with
+.I errno
+set to
+.BR EINTR .
+.RB ( msgrcv ()
+is never automatically restarted after being interrupted by a
+signal handler, regardless of the setting of the
+.B SA_RESTART
+flag when establishing a signal handler.)
+.P
+Upon successful completion the message queue data structure is updated
+as follows:
+.IP
+.I msg_lrpid
+is set to the process ID of the calling process.
+.IP
+.I msg_qnum
+is decremented by 1.
+.IP
+.I msg_rtime
+is set to the current time.
+.SH RETURN VALUE
+On success,
+.BR msgsnd ()
+returns 0
+and
+.BR msgrcv ()
+returns the number of bytes actually copied into the
+.I mtext
+array.
+On failure, both functions return \-1, and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.BR msgsnd ()
+can fail with the following errors:
+.TP
+.B EACCES
+The calling process does not have write permission on the message queue,
+and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EAGAIN
+The message can't be sent due to the
+.I msg_qbytes
+limit for the queue and
+.B IPC_NOWAIT
+was specified in
+.IR msgflg .
+.TP
+.B EFAULT
+The address pointed to by
+.I msgp
+isn't accessible.
+.TP
+.B EIDRM
+The message queue was removed.
+.TP
+.B EINTR
+Sleeping on a full message queue condition, the process caught a signal.
+.TP
+.B EINVAL
+Invalid
+.I msqid
+value, or nonpositive
+.I mtype
+value, or
+invalid
+.I msgsz
+value (less than 0 or greater than the system value
+.BR MSGMAX ).
+.TP
+.B ENOMEM
+The system does not have enough memory to make a copy of the
+message pointed to by
+.IR msgp .
+.P
+.BR msgrcv ()
+can fail with the following errors:
+.TP
+.B E2BIG
+The message text length is greater than
+.I msgsz
+and
+.B MSG_NOERROR
+isn't specified in
+.IR msgflg .
+.TP
+.B EACCES
+The calling process does not have read permission on the message queue,
+and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EFAULT
+The address pointed to by
+.I msgp
+isn't accessible.
+.TP
+.B EIDRM
+While the process was sleeping to receive a message,
+the message queue was removed.
+.TP
+.B EINTR
+While the process was sleeping to receive a message,
+the process caught a signal; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I msqid
+was invalid, or
+.I msgsz
+was less than 0.
+.TP
+.BR EINVAL " (since Linux 3.14)"
+.I msgflg
+specified
+.BR MSG_COPY ,
+but not
+.BR IPC_NOWAIT .
+.TP
+.BR EINVAL " (since Linux 3.14)"
+.I msgflg
+specified both
+.B MSG_COPY
+and
+.BR MSG_EXCEPT .
+.TP
+.B ENOMSG
+.B IPC_NOWAIT
+was specified in
+.I msgflg
+and no message of the requested type existed on the message queue.
+.TP
+.B ENOMSG
+.B IPC_NOWAIT
+and
+.B MSG_COPY
+were specified in
+.I msgflg
+and the queue contains less than
+.I msgtyp
+messages.
+.TP
+.BR ENOSYS " (since Linux 3.8)"
+Both
+.B MSG_COPY
+and
+.B IPC_NOWAIT
+were specified in
+.IR msgflg ,
+and this kernel was configured without
+.BR CONFIG_CHECKPOINT_RESTORE .
+.SH STANDARDS
+POSIX.1-2008.
+.P
+The
+.B MSG_EXCEPT
+and
+.B MSG_COPY
+flags are Linux-specific;
+their definitions can be obtained by defining the
+.B _GNU_SOURCE
+.\" MSG_COPY since glibc 2.18
+feature test macro.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.P
+The
+.I msgp
+argument is declared as \fIstruct msgbuf\ *\fP in
+glibc 2.0 and 2.1.
+It is declared as \fIvoid\ *\fP
+in glibc 2.2 and later, as required by SUSv2 and SUSv3.
+.SH NOTES
+The following limits on message queue resources affect the
+.BR msgsnd ()
+call:
+.TP
+.B MSGMAX
+Maximum size of a message text, in bytes (default value: 8192 bytes).
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/msgmax .
+.TP
+.B MSGMNB
+Maximum number of bytes that can be held in a message queue
+(default value: 16384 bytes).
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/msgmnb .
+A privileged process
+(Linux: a process with the
+.B CAP_SYS_RESOURCE
+capability)
+can increase the size of a message queue beyond
+.B MSGMNB
+using the
+.BR msgctl (2)
+.B IPC_SET
+operation.
+.P
+The implementation has no intrinsic system-wide limits on the
+number of message headers
+.RB ( MSGTQL )
+and the number of bytes in the message pool
+.RB ( MSGPOOL ).
+.SH BUGS
+In Linux 3.13 and earlier,
+if
+.BR msgrcv ()
+was called with the
+.B MSG_COPY
+flag, but without
+.BR IPC_NOWAIT ,
+and the message queue contained less than
+.I msgtyp
+messages, then the call would block until the next message is written
+to the queue.
+.\" http://marc.info/?l=linux-kernel&m=139048542803605&w=2
+At that point, the call would return a copy of the message,
+.I regardless
+of whether that message was at the ordinal position
+.IR msgtyp .
+This bug is fixed
+.\" commit 4f87dac386cc43d5525da7a939d4b4e7edbea22c
+in Linux 3.14.
+.P
+Specifying both
+.B MSG_COPY
+and
+.B MSC_EXCEPT
+in
+.I msgflg
+is a logical error (since these flags impose different interpretations on
+.IR msgtyp ).
+In Linux 3.13 and earlier,
+.\" http://marc.info/?l=linux-kernel&m=139048542803605&w=2
+this error was not diagnosed by
+.BR msgrcv ().
+This bug is fixed
+.\" commit 4f87dac386cc43d5525da7a939d4b4e7edbea22c
+in Linux 3.14.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR msgsnd ()
+and
+.BR msgrcv ().
+.P
+The example program is first run with the \fB\-s\fP option to send a
+message and then run again with the \fB\-r\fP option to receive a
+message.
+.P
+The following shell session shows a sample run of the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \-s"
+sent: a message at Wed Mar  4 16:25:45 2015
+.P
+.RB "$" " ./a.out \-r"
+message received: a message at Wed Mar  4 16:25:45 2015
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (msgop.c)
+.EX
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ipc.h>
+#include <sys/msg.h>
+#include <time.h>
+#include <unistd.h>
+\&
+struct msgbuf {
+    long mtype;
+    char mtext[80];
+};
+\&
+static void
+usage(char *prog_name, char *msg)
+{
+    if (msg != NULL)
+        fputs(msg, stderr);
+\&
+    fprintf(stderr, "Usage: %s [options]\en", prog_name);
+    fprintf(stderr, "Options are:\en");
+    fprintf(stderr, "\-s        send message using msgsnd()\en");
+    fprintf(stderr, "\-r        read message using msgrcv()\en");
+    fprintf(stderr, "\-t        message type (default is 1)\en");
+    fprintf(stderr, "\-k        message queue key (default is 1234)\en");
+    exit(EXIT_FAILURE);
+}
+\&
+static void
+send_msg(int qid, int msgtype)
+{
+    time_t         t;
+    struct msgbuf  msg;
+\&
+    msg.mtype = msgtype;
+\&
+    time(&t);
+    snprintf(msg.mtext, sizeof(msg.mtext), "a message at %s",
+             ctime(&t));
+\&
+    if (msgsnd(qid, &msg, sizeof(msg.mtext),
+               IPC_NOWAIT) == \-1)
+    {
+        perror("msgsnd error");
+        exit(EXIT_FAILURE);
+    }
+    printf("sent: %s\en", msg.mtext);
+}
+\&
+static void
+get_msg(int qid, int msgtype)
+{
+    struct msgbuf msg;
+\&
+    if (msgrcv(qid, &msg, sizeof(msg.mtext), msgtype,
+               MSG_NOERROR | IPC_NOWAIT) == \-1) {
+        if (errno != ENOMSG) {
+            perror("msgrcv");
+            exit(EXIT_FAILURE);
+        }
+        printf("No message available for msgrcv()\en");
+    } else {
+        printf("message received: %s\en", msg.mtext);
+    }
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int  qid, opt;
+    int  mode = 0;               /* 1 = send, 2 = receive */
+    int  msgtype = 1;
+    int  msgkey = 1234;
+\&
+    while ((opt = getopt(argc, argv, "srt:k:")) != \-1) {
+        switch (opt) {
+        case \[aq]s\[aq]:
+            mode = 1;
+            break;
+        case \[aq]r\[aq]:
+            mode = 2;
+            break;
+        case \[aq]t\[aq]:
+            msgtype = atoi(optarg);
+            if (msgtype <= 0)
+                usage(argv[0], "\-t option must be greater than 0\en");
+            break;
+        case \[aq]k\[aq]:
+            msgkey = atoi(optarg);
+            break;
+        default:
+            usage(argv[0], "Unrecognized option\en");
+        }
+    }
+\&
+    if (mode == 0)
+        usage(argv[0], "must use either \-s or \-r option\en");
+\&
+    qid = msgget(msgkey, IPC_CREAT | 0666);
+\&
+    if (qid == \-1) {
+        perror("msgget");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (mode == 2)
+        get_msg(qid, msgtype);
+    else
+        send_msg(qid, msgtype);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR msgctl (2),
+.BR msgget (2),
+.BR capabilities (7),
+.BR mq_overview (7),
+.BR sysvipc (7)
diff --git a/man/man2/msgrcv.2 b/man/man2/msgrcv.2
new file mode 100644
index 000000000..b34869edf
--- /dev/null
+++ b/man/man2/msgrcv.2
@@ -0,0 +1 @@
+.so man2/msgop.2
diff --git a/man/man2/msgsnd.2 b/man/man2/msgsnd.2
new file mode 100644
index 000000000..b34869edf
--- /dev/null
+++ b/man/man2/msgsnd.2
@@ -0,0 +1 @@
+.so man2/msgop.2
diff --git a/man/man2/msync.2 b/man/man2/msync.2
new file mode 100644
index 000000000..f46b0ff90
--- /dev/null
+++ b/man/man2/msync.2
@@ -0,0 +1,140 @@
+.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH msync 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+msync \- synchronize a file with a memory map
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "int msync(void " addr [. length "], size_t " length ", int " flags );
+.fi
+.SH DESCRIPTION
+.BR msync ()
+flushes changes made to the in-core copy of a file that was mapped
+into memory using
+.BR mmap (2)
+back to the filesystem.
+Without use of this call,
+there is no guarantee that changes are written back before
+.BR munmap (2)
+is called.
+To be more precise, the part of the file that
+corresponds to the memory area starting at
+.I addr
+and having length
+.I length
+is updated.
+.P
+The
+.I flags
+argument should specify exactly one of
+.B MS_ASYNC
+and
+.BR MS_SYNC ,
+and may additionally include the
+.B MS_INVALIDATE
+bit.
+These bits have the following meanings:
+.TP
+.B MS_ASYNC
+Specifies that an update be scheduled, but the call returns immediately.
+.TP
+.B MS_SYNC
+Requests an update and waits for it to complete.
+.TP
+.B MS_INVALIDATE
+.\" Since Linux 2.4, this seems to be a no-op (other than the
+.\" EBUSY check for VM_LOCKED).
+Asks to invalidate other mappings of the same file
+(so that they can be updated with the fresh values just written).
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBUSY
+.B MS_INVALIDATE
+was specified in
+.IR flags ,
+and a memory lock exists for the specified address range.
+.TP
+.B EINVAL
+.I addr
+is not a multiple of PAGESIZE; or any bit other than
+.BR MS_ASYNC " | " MS_INVALIDATE " | " MS_SYNC
+is set in
+.IR flags ;
+or both
+.B MS_SYNC
+and
+.B MS_ASYNC
+are set in
+.IR flags .
+.TP
+.B ENOMEM
+The indicated memory (or part of it) was not mapped.
+.SH VERSIONS
+According to POSIX, either
+.B MS_SYNC
+or
+.B MS_ASYNC
+must be specified in
+.IR flags ,
+and indeed failure to include one of these flags will cause
+.BR msync ()
+to fail on some systems.
+However, Linux permits a call to
+.BR msync ()
+that specifies neither of these flags,
+with semantics that are (currently) equivalent to specifying
+.BR MS_ASYNC .
+(Since Linux 2.6.19,
+.\" commit 204ec841fbea3e5138168edbc3a76d46747cc987
+.B MS_ASYNC
+is in fact a no-op, since the kernel properly tracks dirty
+pages and flushes them to storage as necessary.)
+Notwithstanding the Linux behavior,
+portable, future-proof applications should ensure that they specify either
+.B MS_SYNC
+or
+.B MS_ASYNC
+in
+.IR flags .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+This call was introduced in Linux 1.3.21, and then used
+.B EFAULT
+instead of
+.BR ENOMEM .
+In Linux 2.4.19, this was changed to the POSIX value
+.BR ENOMEM .
+.P
+On POSIX systems on which
+.BR msync ()
+is available, both
+.B _POSIX_MAPPED_FILES
+and
+.B _POSIX_SYNCHRONIZED_IO
+are defined in
+.I <unistd.h>
+to a value greater than 0.
+(See also
+.BR sysconf (3).)
+.\" POSIX.1-2001: It shall be defined to -1 or 0 or 200112L.
+.\" -1: unavailable, 0: ask using sysconf().
+.\" glibc defines them to 1.
+.SH SEE ALSO
+.BR mmap (2)
+.P
+B.O. Gallmeister, POSIX.4, O'Reilly, pp. 128\[en]129 and 389\[en]391.
diff --git a/man/man2/munlock.2 b/man/man2/munlock.2
new file mode 100644
index 000000000..5e5b3c741
--- /dev/null
+++ b/man/man2/munlock.2
@@ -0,0 +1 @@
+.so man2/mlock.2
diff --git a/man/man2/munlockall.2 b/man/man2/munlockall.2
new file mode 100644
index 000000000..5e5b3c741
--- /dev/null
+++ b/man/man2/munlockall.2
@@ -0,0 +1 @@
+.so man2/mlock.2
diff --git a/man/man2/munmap.2 b/man/man2/munmap.2
new file mode 100644
index 000000000..8902d1b35
--- /dev/null
+++ b/man/man2/munmap.2
@@ -0,0 +1 @@
+.so man2/mmap.2
diff --git a/man/man2/name_to_handle_at.2 b/man/man2/name_to_handle_at.2
new file mode 100644
index 000000000..090521c86
--- /dev/null
+++ b/man/man2/name_to_handle_at.2
@@ -0,0 +1 @@
+.so man2/open_by_handle_at.2
diff --git a/man/man2/nanosleep.2 b/man/man2/nanosleep.2
new file mode 100644
index 000000000..e7132ee32
--- /dev/null
+++ b/man/man2/nanosleep.2
@@ -0,0 +1,221 @@
+.\" Copyright (C) Markus Kuhn, 1996
+.\" and Copyright (C) Linux Foundation, 2008, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1996-04-10  Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"             First version written
+.\" Modified, 2004-10-24, aeb
+.\" 2008-06-24, mtk
+.\"     Minor rewrites of some parts.
+.\"     NOTES: describe case where clock_nanosleep() can be preferable.
+.\"     NOTES: describe CLOCK_REALTIME versus CLOCK_NANOSLEEP
+.\"     Replace crufty discussion of HZ with a pointer to time(7).
+.TH nanosleep 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nanosleep \- high-resolution sleep
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "int nanosleep(const struct timespec *" duration ,
+.BI "              struct timespec *_Nullable " rem );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR nanosleep ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+.BR nanosleep ()
+suspends the execution of the calling thread
+until either at least the time specified in
+.I *duration
+has elapsed, or the delivery of a signal
+that triggers the invocation of a handler in the calling thread or
+that terminates the process.
+.P
+If the call is interrupted by a signal handler,
+.BR nanosleep ()
+returns \-1, sets
+.I errno
+to
+.BR EINTR ,
+and writes the remaining time into the structure pointed to by
+.I rem
+unless
+.I rem
+is NULL.
+The value of
+.I *rem
+can then be used to call
+.BR nanosleep ()
+again and complete the specified pause (but see NOTES).
+.P
+The
+.BR timespec (3)
+structure
+is used to specify intervals of time with nanosecond precision.
+.P
+The value of the nanoseconds field must be in the range [0, 999999999].
+.P
+Compared to
+.BR sleep (3)
+and
+.BR usleep (3),
+.BR nanosleep ()
+has the following advantages:
+it provides a higher resolution for specifying the sleep interval;
+POSIX.1 explicitly specifies that it
+does not interact with signals;
+and it makes the task of resuming a sleep that has been
+interrupted by a signal handler easier.
+.SH RETURN VALUE
+On successfully sleeping for the requested duration,
+.BR nanosleep ()
+returns 0.
+If the call is interrupted by a signal handler or encounters an error,
+then it returns \-1, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Problem with copying information from user space.
+.TP
+.B EINTR
+The pause has been interrupted by a signal that was
+delivered to the thread (see
+.BR signal (7)).
+The remaining sleep time has been written
+into
+.I *rem
+so that the thread can easily call
+.BR nanosleep ()
+again and continue with the pause.
+.TP
+.B EINVAL
+The value in the
+.I tv_nsec
+field was not in the range [0, 999999999] or
+.I tv_sec
+was negative.
+.SH VERSIONS
+POSIX.1 specifies that
+.BR nanosleep ()
+should measure time against the
+.B CLOCK_REALTIME
+clock.
+However, Linux measures the time using the
+.B CLOCK_MONOTONIC
+clock.
+.\" See also http://thread.gmane.org/gmane.linux.kernel/696854/
+.\" Subject: nanosleep() uses CLOCK_MONOTONIC, should be CLOCK_REALTIME?
+.\" Date: 2008-06-22 07:35:41 GMT
+This probably does not matter, since the POSIX.1 specification for
+.BR clock_settime (2)
+says that discontinuous changes in
+.B CLOCK_REALTIME
+should not affect
+.BR nanosleep ():
+.RS
+.P
+Setting the value of the
+.B CLOCK_REALTIME
+clock via
+.BR clock_settime (2)
+shall
+have no effect on threads that are blocked waiting for a relative time
+service based upon this clock, including the
+.BR nanosleep ()
+function; ...
+Consequently,
+these time services shall expire when the requested duration elapses,
+independently of the new or old value of the clock.
+.RE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+In order to support applications requiring much more precise pauses
+(e.g., in order to control some time-critical hardware),
+.BR nanosleep ()
+would handle pauses of up to 2 milliseconds by busy waiting with microsecond
+precision when called from a thread scheduled under a real-time policy
+like
+.B SCHED_FIFO
+or
+.BR SCHED_RR .
+This special extension was removed in Linux 2.5.39,
+and is thus not available in Linux 2.6.0 and later kernels.
+.SH NOTES
+If the
+.I duration
+is not an exact multiple of the granularity underlying clock (see
+.BR time (7)),
+then the interval will be rounded up to the next multiple.
+Furthermore, after the sleep completes, there may still be a delay before
+the CPU becomes free to once again execute the calling thread.
+.P
+The fact that
+.BR nanosleep ()
+sleeps for a relative interval can be problematic if the call
+is repeatedly restarted after being interrupted by signals,
+since the time between the interruptions and restarts of the call
+will lead to drift in the time when the sleep finally completes.
+This problem can be avoided by using
+.BR clock_nanosleep (2)
+with an absolute time value.
+.SH BUGS
+If a program that catches signals and uses
+.BR nanosleep ()
+receives signals at a very high rate,
+then scheduling delays and rounding errors in the kernel's
+calculation of the sleep interval and the returned
+.I remain
+value mean that the
+.I remain
+value may steadily
+.I increase
+on successive restarts of the
+.BR nanosleep ()
+call.
+To avoid such problems, use
+.BR clock_nanosleep (2)
+with the
+.B TIMER_ABSTIME
+flag to sleep to an absolute deadline.
+.P
+In Linux 2.4, if
+.BR nanosleep ()
+is stopped by a signal (e.g.,
+.BR SIGTSTP ),
+then the call fails with the error
+.B EINTR
+after the thread is resumed by a
+.B SIGCONT
+signal.
+If the system call is subsequently restarted,
+then the time that the thread spent in the stopped state is
+.I not
+counted against the sleep interval.
+This problem is fixed in Linux 2.6.0 and later kernels.
+.SH SEE ALSO
+.BR clock_nanosleep (2),
+.BR restart_syscall (2),
+.BR sched_setscheduler (2),
+.BR timer_create (2),
+.BR sleep (3),
+.BR timespec (3),
+.BR usleep (3),
+.BR time (7)
diff --git a/man/man2/newfstatat.2 b/man/man2/newfstatat.2
new file mode 100644
index 000000000..7791269e6
--- /dev/null
+++ b/man/man2/newfstatat.2
@@ -0,0 +1 @@
+.so man2/fstatat.2
diff --git a/man/man2/nfsservctl.2 b/man/man2/nfsservctl.2
new file mode 100644
index 000000000..462fda2ac
--- /dev/null
+++ b/man/man2/nfsservctl.2
@@ -0,0 +1,70 @@
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This text is in the public domain.
+.\" %%%LICENSE_END
+.\"
+.TH nfsservctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nfsservctl \- syscall interface to kernel nfs daemon
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <linux/nfsd/syscall.h>
+.P
+.BI "long nfsservctl(int " cmd ", struct nfsctl_arg *" argp ,
+.BI "                union nfsctl_res *" resp );
+.fi
+.SH DESCRIPTION
+.IR Note :
+Since Linux 3.1, this system call no longer exists.
+It has been replaced by a set of files in the
+.I nfsd
+filesystem; see
+.BR nfsd (7).
+.P
+.in +4n
+.EX
+/*
+ * These are the commands understood by nfsctl().
+ */
+#define NFSCTL_SVC        0  /* This is a server process. */
+#define NFSCTL_ADDCLIENT  1  /* Add an NFS client. */
+#define NFSCTL_DELCLIENT  2  /* Remove an NFS client. */
+#define NFSCTL_EXPORT     3  /* Export a filesystem. */
+#define NFSCTL_UNEXPORT   4  /* Unexport a filesystem. */
+#define NFSCTL_UGIDUPDATE 5  /* Update a client\[aq]s UID/GID map
+                                (only in Linux 2.4.x and earlier). */
+#define NFSCTL_GETFH      6  /* Get a file handle (used by mountd(8))
+                                (only in Linux 2.4.x and earlier). */
+\&
+struct nfsctl_arg {
+    int                       ca_version;     /* safeguard */
+    union {
+        struct nfsctl_svc     u_svc;
+        struct nfsctl_client  u_client;
+        struct nfsctl_export  u_export;
+        struct nfsctl_uidmap  u_umap;
+        struct nfsctl_fhparm  u_getfh;
+        unsigned int          u_debug;
+    } u;
+}
+\&
+union nfsctl_res {
+        struct knfs_fh          cr_getfh;
+        unsigned int            cr_debug;
+};
+.EE
+.in
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Removed in Linux 3.1.
+Removed in glibc 2.28.
+.SH SEE ALSO
+.BR nfsd (7)
diff --git a/man/man2/nice.2 b/man/man2/nice.2
new file mode 100644
index 000000000..20d8d8ec1
--- /dev/null
+++ b/man/man2/nice.2
@@ -0,0 +1,118 @@
+.\" Copyright (c) 1992 Drew Eckhardt <drew@cs.colorado.edu>, March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-11-04 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-06-04 by aeb
+.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH nice 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nice \- change process priority
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int nice(int " inc );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR nice ():
+.nf
+    _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+.BR nice ()
+adds
+.I inc
+to the nice value for the calling thread.
+(A higher nice value means a lower priority.)
+.P
+The range of the nice value is +19 (low priority) to \-20 (high priority).
+Attempts to set a nice value outside the range are clamped to the range.
+.P
+Traditionally, only a privileged process could lower the nice value
+(i.e., set a higher priority).
+However, since Linux 2.6.12, an unprivileged process can decrease
+the nice value of a target process that has a suitable
+.B RLIMIT_NICE
+soft limit; see
+.BR getrlimit (2)
+for details.
+.SH RETURN VALUE
+On success, the new nice value is returned (but see NOTES below).
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+A successful call can legitimately return \-1.
+To detect an error, set
+.I errno
+to 0 before the call, and check whether it is nonzero after
+.BR nice ()
+returns \-1.
+.SH ERRORS
+.TP
+.B EPERM
+The calling process attempted to increase its priority by
+supplying a negative
+.I inc
+but has insufficient privileges.
+Under Linux, the
+.B CAP_SYS_NICE
+capability is required.
+(But see the discussion of the
+.B RLIMIT_NICE
+resource limit in
+.BR setrlimit (2).)
+.SH VERSIONS
+.SS C library/kernel differences
+POSIX.1 specifies that
+.BR nice ()
+should return the new nice value.
+However, the raw Linux system call returns 0 on success.
+Likewise, the
+.BR nice ()
+wrapper function provided in glibc 2.2.3 and earlier returns 0 on success.
+.P
+Since glibc 2.2.4, the
+.BR nice ()
+wrapper function provided by glibc provides conformance to POSIX.1 by calling
+.BR getpriority (2)
+to obtain the new nice value, which is then returned to the caller.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.\" SVr4 documents an additional
+.\" .B EINVAL
+.\" error code.
+.SH NOTES
+For further details on the nice value, see
+.BR sched (7).
+.P
+.IR Note :
+the addition of the "autogroup" feature in Linux 2.6.38 means that
+the nice value no longer has its traditional effect in many circumstances.
+For details, see
+.BR sched (7).
+.SH SEE ALSO
+.BR nice (1),
+.BR renice (1),
+.BR fork (2),
+.BR getpriority (2),
+.BR getrlimit (2),
+.BR setpriority (2),
+.BR capabilities (7),
+.BR sched (7)
diff --git a/man/man2/oldfstat.2 b/man/man2/oldfstat.2
new file mode 100644
index 000000000..b1a86c195
--- /dev/null
+++ b/man/man2/oldfstat.2
@@ -0,0 +1 @@
+.so man2/stat.2
diff --git a/man/man2/oldlstat.2 b/man/man2/oldlstat.2
new file mode 100644
index 000000000..b1a86c195
--- /dev/null
+++ b/man/man2/oldlstat.2
@@ -0,0 +1 @@
+.so man2/stat.2
diff --git a/man/man2/oldolduname.2 b/man/man2/oldolduname.2
new file mode 100644
index 000000000..450f7b1ca
--- /dev/null
+++ b/man/man2/oldolduname.2
@@ -0,0 +1 @@
+.so man2/uname.2
diff --git a/man/man2/oldstat.2 b/man/man2/oldstat.2
new file mode 100644
index 000000000..b1a86c195
--- /dev/null
+++ b/man/man2/oldstat.2
@@ -0,0 +1 @@
+.so man2/stat.2
diff --git a/man/man2/olduname.2 b/man/man2/olduname.2
new file mode 100644
index 000000000..450f7b1ca
--- /dev/null
+++ b/man/man2/olduname.2
@@ -0,0 +1 @@
+.so man2/uname.2
diff --git a/man/man2/open.2 b/man/man2/open.2
new file mode 100644
index 000000000..1e98a1df4
--- /dev/null
+++ b/man/man2/open.2
@@ -0,0 +1,1941 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\" and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\" and Copyright (C) 2008 Greg Banks
+.\" and Copyright (C) 2006, 2008, 2013, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1994-08-21 by Michael Haardt
+.\" Modified 1996-04-13 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 1996-05-13 by Thomas Koenig
+.\" Modified 1996-12-20 by Michael Haardt
+.\" Modified 1999-02-19 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 1998-11-28 by Joseph S. Myers <jsm28@hermes.cam.ac.uk>
+.\" Modified 1999-06-03 by Michael Haardt
+.\" Modified 2002-05-07 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2004-12-08, mtk, reordered flags list alphabetically
+.\" 2004-12-08, Martin Pool <mbp@sourcefrog.net> (& mtk), added O_NOATIME
+.\" 2007-09-18, mtk, Added description of O_CLOEXEC + other minor edits
+.\" 2008-01-03, mtk, with input from Trond Myklebust
+.\"     <trond.myklebust@fys.uio.no> and Timo Sirainen <tss@iki.fi>
+.\"     Rewrite description of O_EXCL.
+.\" 2008-01-11, Greg Banks <gnb@melbourne.sgi.com>: add more detail
+.\"     on O_DIRECT.
+.\" 2008-02-26, Michael Haardt: Reorganized text for O_CREAT and mode
+.\"
+.\" FIXME . Apr 08: The next POSIX revision has O_EXEC, O_SEARCH, and
+.\" O_TTYINIT.  Eventually these may need to be documented.  --mtk
+.\"
+.TH open 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+open, openat, creat \- open and possibly create a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <fcntl.h>
+.P
+.BI "int open(const char *" pathname ", int " flags ", ..."
+.BI "           \fR/*\fP mode_t " mode " \fR*/\fP );"
+.P
+.BI "int creat(const char *" pathname ", mode_t " mode );
+.P
+.BI "int openat(int " dirfd ", const char *" pathname ", int " flags ", ..."
+.BI "           \fR/*\fP mode_t " mode " \fR*/\fP );"
+.P
+/* Documented separately, in \c
+.BR openat2 (2):\c
+\& */
+.BI "int openat2(int " dirfd ", const char *" pathname ,
+.BI "           const struct open_how *" how ", size_t " size );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR openat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR open ()
+system call opens the file specified by
+.IR pathname .
+If the specified file does not exist,
+it may optionally (if
+.B O_CREAT
+is specified in
+.IR flags )
+be created by
+.BR open ().
+.P
+The return value of
+.BR open ()
+is a file descriptor, a small, nonnegative integer that is an index
+to an entry in the process's table of open file descriptors.
+The file descriptor is used
+in subsequent system calls
+(\c
+.BR read (2),
+.BR write (2),
+.BR lseek (2),
+.BR fcntl (2),
+etc.)
+to refer to the open file.
+The file descriptor returned by a successful call will be
+the lowest-numbered file descriptor not currently open for the process.
+.P
+By default, the new file descriptor is set to remain open across an
+.BR execve (2)
+(i.e., the
+.B FD_CLOEXEC
+file descriptor flag described in
+.BR fcntl (2)
+is initially disabled); the
+.B O_CLOEXEC
+flag, described below, can be used to change this default.
+The file offset is set to the beginning of the file (see
+.BR lseek (2)).
+.P
+A call to
+.BR open ()
+creates a new
+.IR "open file description" ,
+an entry in the system-wide table of open files.
+The open file description records the file offset and the file status flags
+(see below).
+A file descriptor is a reference to an open file description;
+this reference is unaffected if
+.I pathname
+is subsequently removed or modified to refer to a different file.
+For further details on open file descriptions, see NOTES.
+.P
+The argument
+.I flags
+must include one of the following
+.IR "access modes" :
+.BR O_RDONLY ", " O_WRONLY ", or " O_RDWR .
+These request opening the file read-only, write-only, or read/write,
+respectively.
+.P
+In addition, zero or more file creation flags and file status flags
+can be
+bitwise ORed
+in
+.IR flags .
+The
+.I file creation flags
+are
+.BR O_CLOEXEC ,
+.BR O_CREAT ,
+.BR O_DIRECTORY ,
+.BR O_EXCL ,
+.BR O_NOCTTY ,
+.BR O_NOFOLLOW ,
+.BR O_TMPFILE ,
+and
+.BR O_TRUNC .
+The
+.I file status flags
+are all of the remaining flags listed below.
+.\" SUSv4 divides the flags into:
+.\" * Access mode
+.\" * File creation
+.\" * File status
+.\" * Other (O_CLOEXEC, O_DIRECTORY, O_NOFOLLOW)
+.\" though it's not clear what the difference between "other" and
+.\" "File creation" flags is.  I raised an Aardvark to see if this
+.\" can be clarified in SUSv4; 10 Oct 2008.
+.\" http://thread.gmane.org/gmane.comp.standards.posix.austin.general/64/focus=67
+.\" TC1 (balloted in 2013), resolved this, so that those three constants
+.\" are also categorized" as file status flags.
+.\"
+The distinction between these two groups of flags is that
+the file creation flags affect the semantics of the open operation itself,
+while the file status flags affect the semantics of subsequent I/O operations.
+The file status flags can be retrieved and (in some cases)
+modified; see
+.BR fcntl (2)
+for details.
+.P
+The full list of file creation flags and file status flags is as follows:
+.TP
+.B O_APPEND
+The file is opened in append mode.
+Before each
+.BR write (2),
+the file offset is positioned at the end of the file,
+as if with
+.BR lseek (2).
+The modification of the file offset and the write operation
+are performed as a single atomic step.
+.IP
+.B O_APPEND
+may lead to corrupted files on NFS filesystems if more than one process
+appends data to a file at once.
+.\" For more background, see
+.\" http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=453946
+.\" http://nfs.sourceforge.net/
+This is because NFS does not support
+appending to a file, so the client kernel has to simulate it, which
+can't be done without a race condition.
+.TP
+.B O_ASYNC
+Enable signal-driven I/O:
+generate a signal
+.RB ( SIGIO
+by default, but this can be changed via
+.BR fcntl (2))
+when input or output becomes possible on this file descriptor.
+This feature is available only for terminals, pseudoterminals,
+sockets, and (since Linux 2.6) pipes and FIFOs.
+See
+.BR fcntl (2)
+for further details.
+See also BUGS, below.
+.TP
+.BR O_CLOEXEC " (since Linux 2.6.23)"
+.\" NOTE! several other man pages refer to this text
+Enable the close-on-exec flag for the new file descriptor.
+.\" FIXME . for later review when Issue 8 is one day released...
+.\" POSIX proposes to fix many APIs that provide hidden FDs
+.\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
+.\" http://austingroupbugs.net/view.php?id=368
+Specifying this flag permits a program to avoid additional
+.BR fcntl (2)
+.B F_SETFD
+operations to set the
+.B FD_CLOEXEC
+flag.
+.IP
+Note that the use of this flag is essential in some multithreaded programs,
+because using a separate
+.BR fcntl (2)
+.B F_SETFD
+operation to set the
+.B FD_CLOEXEC
+flag does not suffice to avoid race conditions
+where one thread opens a file descriptor and
+attempts to set its close-on-exec flag using
+.BR fcntl (2)
+at the same time as another thread does a
+.BR fork (2)
+plus
+.BR execve (2).
+Depending on the order of execution,
+the race may lead to the file descriptor returned by
+.BR open ()
+being unintentionally leaked to the program executed by the child process
+created by
+.BR fork (2).
+(This kind of race is in principle possible for any system call
+that creates a file descriptor whose close-on-exec flag should be set,
+and various other Linux system calls provide an equivalent of the
+.B O_CLOEXEC
+flag to deal with this problem.)
+.\" This flag fixes only one form of the race condition;
+.\" The race can also occur with, for example, file descriptors
+.\" returned by accept(), pipe(), etc.
+.TP
+.B O_CREAT
+If
+.I pathname
+does not exist, create it as a regular file.
+.IP
+The owner (user ID) of the new file is set to the effective user ID
+of the process.
+.IP
+The group ownership (group ID) of the new file is set either to
+the effective group ID of the process (System V semantics)
+or to the group ID of the parent directory (BSD semantics).
+On Linux, the behavior depends on whether the
+set-group-ID mode bit is set on the parent directory:
+if that bit is set, then BSD semantics apply;
+otherwise, System V semantics apply.
+For some filesystems, the behavior also depends on the
+.I bsdgroups
+and
+.I sysvgroups
+mount options described in
+.BR mount (8).
+.\" As at Linux 2.6.25, bsdgroups is supported by ext2, ext3, ext4, and
+.\" XFS (since Linux 2.6.14).
+.IP
+The
+.I mode
+argument specifies the file mode bits to be applied when a new file is created.
+If neither
+.B O_CREAT
+nor
+.B O_TMPFILE
+is specified in
+.IR flags ,
+then
+.I mode
+is ignored (and can thus be specified as 0, or simply omitted).
+The
+.I mode
+argument
+.B must
+be supplied if
+.B O_CREAT
+or
+.B O_TMPFILE
+is specified in
+.IR flags ;
+if it is not supplied,
+some arbitrary bytes from the stack will be applied as the file mode.
+.IP
+The effective mode is modified by the process's
+.I umask
+in the usual way: in the absence of a default ACL, the mode of the
+created file is
+.IR "(mode\ &\ \[ti]umask)" .
+.IP
+Note that
+.I mode
+applies only to future accesses of the
+newly created file; the
+.BR open ()
+call that creates a read-only file may well return a read/write
+file descriptor.
+.IP
+The following symbolic constants are provided for
+.IR mode :
+.RS
+.TP 9
+.B S_IRWXU
+00700 user (file owner) has read, write, and execute permission
+.TP
+.B S_IRUSR
+00400 user has read permission
+.TP
+.B S_IWUSR
+00200 user has write permission
+.TP
+.B S_IXUSR
+00100 user has execute permission
+.TP
+.B S_IRWXG
+00070 group has read, write, and execute permission
+.TP
+.B S_IRGRP
+00040 group has read permission
+.TP
+.B S_IWGRP
+00020 group has write permission
+.TP
+.B S_IXGRP
+00010 group has execute permission
+.TP
+.B S_IRWXO
+00007 others have read, write, and execute permission
+.TP
+.B S_IROTH
+00004 others have read permission
+.TP
+.B S_IWOTH
+00002 others have write permission
+.TP
+.B S_IXOTH
+00001 others have execute permission
+.RE
+.IP
+According to POSIX, the effect when other bits are set in
+.I mode
+is unspecified.
+On Linux, the following bits are also honored in
+.IR mode :
+.RS
+.TP 9
+.B S_ISUID
+0004000 set-user-ID bit
+.TP
+.B S_ISGID
+0002000 set-group-ID bit (see
+.BR inode (7)).
+.TP
+.B S_ISVTX
+0001000 sticky bit (see
+.BR inode (7)).
+.RE
+.TP
+.BR O_DIRECT " (since Linux 2.4.10)"
+Try to minimize cache effects of the I/O to and from this file.
+In general this will degrade performance, but it is useful in
+special situations, such as when applications do their own caching.
+File I/O is done directly to/from user-space buffers.
+The
+.B O_DIRECT
+flag on its own makes an effort to transfer data synchronously,
+but does not give the guarantees of the
+.B O_SYNC
+flag that data and necessary metadata are transferred.
+To guarantee synchronous I/O,
+.B O_SYNC
+must be used in addition to
+.BR O_DIRECT .
+See NOTES below for further discussion.
+.IP
+A semantically similar (but deprecated) interface for block devices
+is described in
+.BR raw (8).
+.TP
+.B O_DIRECTORY
+If \fIpathname\fP is not a directory, cause the open to fail.
+.\" But see the following and its replies:
+.\" http://marc.theaimsgroup.com/?t=112748702800001&r=1&w=2
+.\" [PATCH] open: O_DIRECTORY and O_CREAT together should fail
+.\" O_DIRECTORY | O_CREAT causes O_DIRECTORY to be ignored.
+This flag was added in Linux 2.1.126, to
+avoid denial-of-service problems if
+.BR opendir (3)
+is called on a
+FIFO or tape device.
+.TP
+.B O_DSYNC
+Write operations on the file will complete according to the requirements of
+synchronized I/O
+.I data
+integrity completion.
+.IP
+By the time
+.BR write (2)
+(and similar)
+return, the output data
+has been transferred to the underlying hardware,
+along with any file metadata that would be required to retrieve that data
+(i.e., as though each
+.BR write (2)
+was followed by a call to
+.BR fdatasync (2)).
+.IR "See NOTES below" .
+.TP
+.B O_EXCL
+Ensure that this call creates the file:
+if this flag is specified in conjunction with
+.BR O_CREAT ,
+and
+.I pathname
+already exists, then
+.BR open ()
+fails with the error
+.BR EEXIST .
+.IP
+When these two flags are specified, symbolic links are not followed:
+.\" POSIX.1-2001 explicitly requires this behavior.
+if
+.I pathname
+is a symbolic link, then
+.BR open ()
+fails regardless of where the symbolic link points.
+.IP
+In general, the behavior of
+.B O_EXCL
+is undefined if it is used without
+.BR O_CREAT .
+There is one exception: on Linux 2.6 and later,
+.B O_EXCL
+can be used without
+.B O_CREAT
+if
+.I pathname
+refers to a block device.
+If the block device is in use by the system (e.g., mounted),
+.BR open ()
+fails with the error
+.BR EBUSY .
+.IP
+On NFS,
+.B O_EXCL
+is supported only when using NFSv3 or later on kernel 2.6 or later.
+In NFS environments where
+.B O_EXCL
+support is not provided, programs that rely on it
+for performing locking tasks will contain a race condition.
+Portable programs that want to perform atomic file locking using a lockfile,
+and need to avoid reliance on NFS support for
+.BR O_EXCL ,
+can create a unique file on
+the same filesystem (e.g., incorporating hostname and PID), and use
+.BR link (2)
+to make a link to the lockfile.
+If
+.BR link (2)
+returns 0, the lock is successful.
+Otherwise, use
+.BR stat (2)
+on the unique file to check if its link count has increased to 2,
+in which case the lock is also successful.
+.TP
+.B O_LARGEFILE
+(LFS)
+Allow files whose sizes cannot be represented in an
+.I off_t
+(but can be represented in an
+.IR off64_t )
+to be opened.
+The
+.B _LARGEFILE64_SOURCE
+macro must be defined
+(before including
+.I any
+header files)
+in order to obtain this definition.
+Setting the
+.B _FILE_OFFSET_BITS
+feature test macro to 64 (rather than using
+.BR O_LARGEFILE )
+is the preferred
+method of accessing large files on 32-bit systems (see
+.BR feature_test_macros (7)).
+.TP
+.BR O_NOATIME " (since Linux 2.6.8)"
+Do not update the file last access time
+.RI ( st_atime
+in the inode)
+when the file is
+.BR read (2).
+.IP
+This flag can be employed only if one of the following conditions is true:
+.RS
+.IP \[bu] 3
+The effective UID of the process
+.\" Strictly speaking: the filesystem UID
+matches the owner UID of the file.
+.IP \[bu]
+The calling process has the
+.B CAP_FOWNER
+capability in its user namespace and
+the owner UID of the file has a mapping in the namespace.
+.RE
+.IP
+This flag is intended for use by indexing or backup programs,
+where its use can significantly reduce the amount of disk activity.
+This flag may not be effective on all filesystems.
+One example is NFS, where the server maintains the access time.
+.\" The O_NOATIME flag also affects the treatment of st_atime
+.\" by mmap() and readdir(2), MTK, Dec 04.
+.TP
+.B O_NOCTTY
+If
+.I pathname
+refers to a terminal device\[em]see
+.BR tty (4)\[em]it
+will not become the process's controlling terminal even if the
+process does not have one.
+.TP
+.B O_NOFOLLOW
+If the trailing component (i.e., basename) of
+.I pathname
+is a symbolic link, then the open fails, with the error
+.BR ELOOP .
+Symbolic links in earlier components of the pathname will still be
+followed.
+(Note that the
+.B ELOOP
+error that can occur in this case is indistinguishable from the case where
+an open fails because there are too many symbolic links found
+while resolving components in the prefix part of the pathname.)
+.IP
+This flag is a FreeBSD extension, which was added in Linux 2.1.126,
+and has subsequently been standardized in POSIX.1-2008.
+.IP
+See also
+.B O_PATH
+below.
+.\" The headers from glibc 2.0.100 and later include a
+.\" definition of this flag; \fIkernels before Linux 2.1.126 will ignore it if
+.\" used\fP.
+.TP
+.BR O_NONBLOCK " or " O_NDELAY
+When possible, the file is opened in nonblocking mode.
+Neither the
+.BR open ()
+nor any subsequent I/O operations on the file descriptor which is
+returned will cause the calling process to wait.
+.IP
+Note that the setting of this flag has no effect on the operation of
+.BR poll (2),
+.BR select (2),
+.BR epoll (7),
+and similar,
+since those interfaces merely inform the caller about whether
+a file descriptor is "ready",
+meaning that an I/O operation performed on
+the file descriptor with the
+.B O_NONBLOCK
+flag
+.I clear
+would not block.
+.IP
+Note that this flag has no effect for regular files and block devices;
+that is, I/O operations will (briefly) block when device activity
+is required, regardless of whether
+.B O_NONBLOCK
+is set.
+Since
+.B O_NONBLOCK
+semantics might eventually be implemented,
+applications should not depend upon blocking behavior
+when specifying this flag for regular files and block devices.
+.IP
+For the handling of FIFOs (named pipes), see also
+.BR fifo (7).
+For a discussion of the effect of
+.B O_NONBLOCK
+in conjunction with mandatory file locks and with file leases, see
+.BR fcntl (2).
+.TP
+.BR O_PATH " (since Linux 2.6.39)"
+.\" commit 1abf0c718f15a56a0a435588d1b104c7a37dc9bd
+.\" commit 326be7b484843988afe57566b627fb7a70beac56
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+.\"
+.\" http://thread.gmane.org/gmane.linux.man/2790/focus=3496
+.\"	Subject: Re: [PATCH] open(2): document O_PATH
+.\"	Newsgroups: gmane.linux.man, gmane.linux.kernel
+.\"
+Obtain a file descriptor that can be used for two purposes:
+to indicate a location in the filesystem tree and
+to perform operations that act purely at the file descriptor level.
+The file itself is not opened, and other file operations (e.g.,
+.BR read (2),
+.BR write (2),
+.BR fchmod (2),
+.BR fchown (2),
+.BR fgetxattr (2),
+.BR ioctl (2),
+.BR mmap (2))
+fail with the error
+.BR EBADF .
+.IP
+The following operations
+.I can
+be performed on the resulting file descriptor:
+.RS
+.IP \[bu] 3
+.BR close (2).
+.IP \[bu]
+.BR fchdir (2),
+if the file descriptor refers to a directory
+(since Linux 3.5).
+.\" commit 332a2e1244bd08b9e3ecd378028513396a004a24
+.IP \[bu]
+.BR fstat (2)
+(since Linux 3.6).
+.IP \[bu]
+.\" fstat(): commit 55815f70147dcfa3ead5738fd56d3574e2e3c1c2
+.BR fstatfs (2)
+(since Linux 3.12).
+.\" fstatfs(): commit 9d05746e7b16d8565dddbe3200faa1e669d23bbf
+.IP \[bu]
+Duplicating the file descriptor
+.RB ( dup (2),
+.BR fcntl (2)
+.BR F_DUPFD ,
+etc.).
+.IP \[bu]
+Getting and setting file descriptor flags
+.RB ( fcntl (2)
+.B F_GETFD
+and
+.BR F_SETFD ).
+.IP \[bu]
+Retrieving open file status flags using the
+.BR fcntl (2)
+.B F_GETFL
+operation: the returned flags will include the bit
+.BR O_PATH .
+.IP \[bu]
+Passing the file descriptor as the
+.I dirfd
+argument of
+.BR openat ()
+and the other "*at()" system calls.
+This includes
+.BR linkat (2)
+with
+.B AT_EMPTY_PATH
+(or via procfs using
+.BR AT_SYMLINK_FOLLOW )
+even if the file is not a directory.
+.IP \[bu]
+Passing the file descriptor to another process via a UNIX domain socket
+(see
+.B SCM_RIGHTS
+in
+.BR unix (7)).
+.RE
+.IP
+When
+.B O_PATH
+is specified in
+.IR flags ,
+flag bits other than
+.BR O_CLOEXEC ,
+.BR O_DIRECTORY ,
+and
+.B O_NOFOLLOW
+are ignored.
+.IP
+Opening a file or directory with the
+.B O_PATH
+flag requires no permissions on the object itself
+(but does require execute permission on the directories in the path prefix).
+Depending on the subsequent operation,
+a check for suitable file permissions may be performed (e.g.,
+.BR fchdir (2)
+requires execute permission on the directory referred to
+by its file descriptor argument).
+By contrast,
+obtaining a reference to a filesystem object by opening it with the
+.B O_RDONLY
+flag requires that the caller have read permission on the object,
+even when the subsequent operation (e.g.,
+.BR fchdir (2),
+.BR fstat (2))
+does not require read permission on the object.
+.IP
+If
+.I pathname
+is a symbolic link and the
+.B O_NOFOLLOW
+flag is also specified,
+then the call returns a file descriptor referring to the symbolic link.
+This file descriptor can be used as the
+.I dirfd
+argument in calls to
+.BR fchownat (2),
+.BR fstatat (2),
+.BR linkat (2),
+and
+.BR readlinkat (2)
+with an empty pathname to have the calls operate on the symbolic link.
+.IP
+If
+.I pathname
+refers to an automount point that has not yet been triggered, so no
+other filesystem is mounted on it, then the call returns a file
+descriptor referring to the automount directory without triggering a mount.
+.BR fstatfs (2)
+can then be used to determine if it is, in fact, an untriggered
+automount point
+.RB ( ".f_type == AUTOFS_SUPER_MAGIC" ).
+.IP
+One use of
+.B O_PATH
+for regular files is to provide the equivalent of POSIX.1's
+.B O_EXEC
+functionality.
+This permits us to open a file for which we have execute
+permission but not read permission, and then execute that file,
+with steps something like the following:
+.IP
+.in +4n
+.EX
+char buf[PATH_MAX];
+fd = open("some_prog", O_PATH);
+snprintf(buf, PATH_MAX, "/proc/self/fd/%d", fd);
+execl(buf, "some_prog", (char *) NULL);
+.EE
+.in
+.IP
+An
+.B O_PATH
+file descriptor can also be passed as the argument of
+.BR fexecve (3).
+.TP
+.B O_SYNC
+Write operations on the file will complete according to the requirements of
+synchronized I/O
+.I file
+integrity completion
+(by contrast with the
+synchronized I/O
+.I data
+integrity completion
+provided by
+.BR O_DSYNC .)
+.IP
+By the time
+.BR write (2)
+(or similar)
+returns, the output data and associated file metadata
+have been transferred to the underlying hardware
+(i.e., as though each
+.BR write (2)
+was followed by a call to
+.BR fsync (2)).
+.IR "See NOTES below" .
+.TP
+.BR O_TMPFILE " (since Linux 3.11)"
+.\" commit 60545d0d4610b02e55f65d141c95b18ccf855b6e
+.\" commit f4e0c30c191f87851c4a53454abb55ee276f4a7e
+.\" commit bb458c644a59dbba3a1fe59b27106c5e68e1c4bd
+Create an unnamed temporary regular file.
+The
+.I pathname
+argument specifies a directory;
+an unnamed inode will be created in that directory's filesystem.
+Anything written to the resulting file will be lost when
+the last file descriptor is closed, unless the file is given a name.
+.IP
+.B O_TMPFILE
+must be specified with one of
+.B O_RDWR
+or
+.B O_WRONLY
+and, optionally,
+.BR O_EXCL .
+If
+.B O_EXCL
+is not specified, then
+.BR linkat (2)
+can be used to link the temporary file into the filesystem, making it
+permanent, using code like the following:
+.IP
+.in +4n
+.EX
+char path[PATH_MAX];
+fd = open("/path/to/dir", O_TMPFILE | O_RDWR,
+                        S_IRUSR | S_IWUSR);
+\&
+/* File I/O on \[aq]fd\[aq]... */
+\&
+linkat(fd, "", AT_FDCWD, "/path/for/file", AT_EMPTY_PATH);
+\&
+/* If the caller doesn\[aq]t have the CAP_DAC_READ_SEARCH
+   capability (needed to use AT_EMPTY_PATH with linkat(2)),
+   and there is a proc(5) filesystem mounted, then the
+   linkat(2) call above can be replaced with:
+\&
+snprintf(path, PATH_MAX,  "/proc/self/fd/%d", fd);
+linkat(AT_FDCWD, path, AT_FDCWD, "/path/for/file",
+                        AT_SYMLINK_FOLLOW);
+*/
+.EE
+.in
+.IP
+In this case,
+the
+.BR open ()
+.I mode
+argument determines the file permission mode, as with
+.BR O_CREAT .
+.IP
+Specifying
+.B O_EXCL
+in conjunction with
+.B O_TMPFILE
+prevents a temporary file from being linked into the filesystem
+in the above manner.
+(Note that the meaning of
+.B O_EXCL
+in this case is different from the meaning of
+.B O_EXCL
+otherwise.)
+.IP
+There are two main use cases for
+.\" Inspired by http://lwn.net/Articles/559147/
+.BR O_TMPFILE :
+.RS
+.IP \[bu] 3
+Improved
+.BR tmpfile (3)
+functionality: race-free creation of temporary files that
+(1) are automatically deleted when closed;
+(2) can never be reached via any pathname;
+(3) are not subject to symlink attacks; and
+(4) do not require the caller to devise unique names.
+.IP \[bu]
+Creating a file that is initially invisible, which is then populated
+with data and adjusted to have appropriate filesystem attributes
+.RB ( fchown (2),
+.BR fchmod (2),
+.BR fsetxattr (2),
+etc.)
+before being atomically linked into the filesystem
+in a fully formed state (using
+.BR linkat (2)
+as described above).
+.RE
+.IP
+.B O_TMPFILE
+requires support by the underlying filesystem;
+only a subset of Linux filesystems provide that support.
+In the initial implementation, support was provided in
+the ext2, ext3, ext4, UDF, Minix, and tmpfs filesystems.
+.\" To check for support, grep for "tmpfile" in kernel sources
+Support for other filesystems has subsequently been added as follows:
+XFS (Linux 3.15);
+.\" commit 99b6436bc29e4f10e4388c27a3e4810191cc4788
+.\" commit ab29743117f9f4c22ac44c13c1647fb24fb2bafe
+Btrfs (Linux 3.16);
+.\" commit ef3b9af50bfa6a1f02cd7b3f5124b712b1ba3e3c
+F2FS (Linux 3.16);
+.\" commit 50732df02eefb39ab414ef655979c2c9b64ad21c
+and ubifs (Linux 4.9)
+.TP
+.B O_TRUNC
+If the file already exists and is a regular file and the access mode allows
+writing (i.e., is
+.B O_RDWR
+or
+.BR O_WRONLY )
+it will be truncated to length 0.
+If the file is a FIFO or terminal device file, the
+.B O_TRUNC
+flag is ignored.
+Otherwise, the effect of
+.B O_TRUNC
+is unspecified.
+.SS creat()
+A call to
+.BR creat ()
+is equivalent to calling
+.BR open ()
+with
+.I flags
+equal to
+.BR O_CREAT|O_WRONLY|O_TRUNC .
+.SS openat()
+The
+.BR openat ()
+system call operates in exactly the same way as
+.BR open (),
+except for the differences described here.
+.P
+The
+.I dirfd
+argument is used in conjunction with the
+.I pathname
+argument as follows:
+.IP \[bu] 3
+If the pathname given in
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.IP \[bu]
+If the pathname given in
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR open ()).
+.IP \[bu]
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR open ()
+for a relative pathname).
+In this case,
+.I dirfd
+must be a directory that was opened for reading
+.RB ( O_RDONLY )
+or using the
+.B O_PATH
+flag.
+.P
+If the pathname given in
+.I pathname
+is relative, and
+.I dirfd
+is not a valid file descriptor, an error
+.RB ( EBADF )
+results.
+(Specifying an invalid file descriptor number in
+.I dirfd
+can be used as a means to ensure that
+.I pathname
+is absolute.)
+.\"
+.SS openat2(2)
+The
+.BR openat2 (2)
+system call is an extension of
+.BR openat (),
+and provides a superset of the features of
+.BR openat ().
+It is documented separately, in
+.BR openat2 (2).
+.SH RETURN VALUE
+On success,
+.BR open (),
+.BR openat (),
+and
+.BR creat ()
+return the new file descriptor (a nonnegative integer).
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR open (),
+.BR openat (),
+and
+.BR creat ()
+can fail with the following errors:
+.TP
+.B EACCES
+The requested access to the file is not allowed, or search permission
+is denied for one of the directories in the path prefix of
+.IR pathname ,
+or the file did not exist yet and write access to the parent directory
+is not allowed.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EACCES
+.\" commit 30aba6656f61ed44cba445a3c0d38b296fa9e8f5
+Where
+.B O_CREAT
+is specified, the
+.I protected_fifos
+or
+.I protected_regular
+sysctl is enabled, the file already exists and is a FIFO or regular file, the
+owner of the file is neither the current user nor the owner of the
+containing directory, and the containing directory is both world- or
+group-writable and sticky.
+For details, see the descriptions of
+.I /proc/sys/fs/protected_fifos
+and
+.I /proc/sys/fs/protected_regular
+in
+.BR proc_sys_fs (5).
+.TP
+.B EBADF
+.RB ( openat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EBUSY
+.B O_EXCL
+was specified in
+.I flags
+and
+.I pathname
+refers to a block device that is in use by the system (e.g., it is mounted).
+.TP
+.B EDQUOT
+Where
+.B O_CREAT
+is specified, the file does not exist, and the user's quota of disk
+blocks or inodes on the filesystem has been exhausted.
+.TP
+.B EEXIST
+.I pathname
+already exists and
+.BR O_CREAT " and " O_EXCL
+were used.
+.TP
+.B EFAULT
+.I pathname
+points outside your accessible address space.
+.TP
+.B EFBIG
+See
+.BR EOVERFLOW .
+.TP
+.B EINTR
+While blocked waiting to complete an open of a slow device
+(e.g., a FIFO; see
+.BR fifo (7)),
+the call was interrupted by a signal handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+The filesystem does not support the
+.B O_DIRECT
+flag.
+See
+.B NOTES
+for more information.
+.TP
+.B EINVAL
+Invalid value in
+.\" In particular, __O_TMPFILE instead of O_TMPFILE
+.IR flags .
+.TP
+.B EINVAL
+.B O_TMPFILE
+was specified in
+.IR flags ,
+but neither
+.B O_WRONLY
+nor
+.B O_RDWR
+was specified.
+.TP
+.B EINVAL
+.B O_CREAT
+was specified in
+.I flags
+and the final component ("basename") of the new file's
+.I pathname
+is invalid
+(e.g., it contains characters not permitted by the underlying filesystem).
+.TP
+.B EINVAL
+The final component ("basename") of
+.I pathname
+is invalid
+(e.g., it contains characters not permitted by the underlying filesystem).
+.TP
+.B EISDIR
+.I pathname
+refers to a directory and the access requested involved writing
+(that is,
+.B O_WRONLY
+or
+.B O_RDWR
+is set).
+.TP
+.B EISDIR
+.I pathname
+refers to an existing directory,
+.B O_TMPFILE
+and one of
+.B O_WRONLY
+or
+.B O_RDWR
+were specified in
+.IR flags ,
+but this kernel version does not provide the
+.B O_TMPFILE
+functionality.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B ELOOP
+.I pathname
+was a symbolic link, and
+.I flags
+specified
+.B O_NOFOLLOW
+but not
+.BR O_PATH .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached
+(see the description of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2)).
+.TP
+.B ENAMETOOLONG
+.I pathname
+was too long.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENODEV
+.I pathname
+refers to a device special file and no corresponding device exists.
+(This is a Linux kernel bug; in this situation
+.B ENXIO
+must be returned.)
+.TP
+.B ENOENT
+.B O_CREAT
+is not set and the named file does not exist.
+.TP
+.B ENOENT
+A directory component in
+.I pathname
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOENT
+.I pathname
+refers to a nonexistent directory,
+.B O_TMPFILE
+and one of
+.B O_WRONLY
+or
+.B O_RDWR
+were specified in
+.IR flags ,
+but this kernel version does not provide the
+.B O_TMPFILE
+functionality.
+.TP
+.B ENOMEM
+The named file is a FIFO,
+but memory for the FIFO buffer can't be allocated because
+the per-user hard limit on memory allocation for pipes has been reached
+and the caller is not privileged; see
+.BR pipe (7).
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSPC
+.I pathname
+was to be created but the device containing
+.I pathname
+has no room for the new file.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.I pathname
+is not, in fact, a directory, or \fBO_DIRECTORY\fP was specified and
+.I pathname
+was not a directory.
+.TP
+.B ENOTDIR
+.RB ( openat ())
+.I pathname
+is a relative pathname and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B ENXIO
+.BR O_NONBLOCK " | " O_WRONLY
+is set, the named file is a FIFO, and
+no process has the FIFO open for reading.
+.TP
+.B ENXIO
+The file is a device special file and no corresponding device exists.
+.TP
+.B ENXIO
+The file is a UNIX domain socket.
+.TP
+.B EOPNOTSUPP
+The filesystem containing
+.I pathname
+does not support
+.BR O_TMPFILE .
+.TP
+.B EOVERFLOW
+.I pathname
+refers to a regular file that is too large to be opened.
+The usual scenario here is that an application compiled
+on a 32-bit platform without
+.I \-D_FILE_OFFSET_BITS=64
+tried to open a file whose size exceeds
+.I (1<<31)\-1
+bytes;
+see also
+.B O_LARGEFILE
+above.
+This is the error specified by POSIX.1;
+before Linux 2.6.24, Linux gave the error
+.B EFBIG
+for this case.
+.\" See http://bugzilla.kernel.org/show_bug.cgi?id=7253
+.\" "Open of a large file on 32-bit fails with EFBIG, should be EOVERFLOW"
+.\" Reported 2006-10-03
+.TP
+.B EPERM
+The
+.B O_NOATIME
+flag was specified, but the effective user ID of the caller
+.\" Strictly speaking, it's the filesystem UID... (MTK)
+did not match the owner of the file and the caller was not privileged.
+.TP
+.B EPERM
+The operation was prevented by a file seal; see
+.BR fcntl (2).
+.TP
+.B EROFS
+.I pathname
+refers to a file on a read-only filesystem and write access was
+requested.
+.TP
+.B ETXTBSY
+.I pathname
+refers to an executable image which is currently being executed and
+write access was requested.
+.TP
+.B ETXTBSY
+.I pathname
+refers to a file that is currently in use as a swap file, and the
+.B O_TRUNC
+flag was specified.
+.TP
+.B ETXTBSY
+.I pathname
+refers to a file that is currently being read by the kernel (e.g., for
+module/firmware loading), and write access was requested.
+.TP
+.B EWOULDBLOCK
+The
+.B O_NONBLOCK
+flag was specified, and an incompatible lease was held on the file
+(see
+.BR fcntl (2)).
+.SH VERSIONS
+The (undefined) effect of
+.B O_RDONLY | O_TRUNC
+varies among implementations.
+On many systems the file is actually truncated.
+.\" Linux 2.0, 2.5: truncate
+.\" Solaris 5.7, 5.8: truncate
+.\" Irix 6.5: truncate
+.\" Tru64 5.1B: truncate
+.\" HP-UX 11.22: truncate
+.\" FreeBSD 4.7: truncate
+.SS Synchronized I/O
+The POSIX.1-2008 "synchronized I/O" option
+specifies different variants of synchronized I/O,
+and specifies the
+.BR open ()
+flags
+.BR O_SYNC ,
+.BR O_DSYNC ,
+and
+.B O_RSYNC
+for controlling the behavior.
+Regardless of whether an implementation supports this option,
+it must at least support the use of
+.B O_SYNC
+for regular files.
+.P
+Linux implements
+.B O_SYNC
+and
+.BR O_DSYNC ,
+but not
+.BR O_RSYNC .
+Somewhat incorrectly, glibc defines
+.B O_RSYNC
+to have the same value as
+.BR O_SYNC .
+.RB ( O_RSYNC
+is defined in the Linux header file
+.I <asm/fcntl.h>
+on HP PA-RISC, but it is not used.)
+.P
+.B O_SYNC
+provides synchronized I/O
+.I file
+integrity completion,
+meaning write operations will flush data and all associated metadata
+to the underlying hardware.
+.B O_DSYNC
+provides synchronized I/O
+.I data
+integrity completion,
+meaning write operations will flush data
+to the underlying hardware,
+but will only flush metadata updates that are required
+to allow a subsequent read operation to complete successfully.
+Data integrity completion can reduce the number of disk operations
+that are required for applications that don't need the guarantees
+of file integrity completion.
+.P
+To understand the difference between the two types of completion,
+consider two pieces of file metadata:
+the file last modification timestamp
+.RI ( st_mtime )
+and the file length.
+All write operations will update the last file modification timestamp,
+but only writes that add data to the end of the
+file will change the file length.
+The last modification timestamp is not needed to ensure that
+a read completes successfully, but the file length is.
+Thus,
+.B O_DSYNC
+would only guarantee to flush updates to the file length metadata
+(whereas
+.B O_SYNC
+would also always flush the last modification timestamp metadata).
+.P
+Before Linux 2.6.33, Linux implemented only the
+.B O_SYNC
+flag for
+.BR open ().
+However, when that flag was specified,
+most filesystems actually provided the equivalent of synchronized I/O
+.I data
+integrity completion (i.e.,
+.B O_SYNC
+was actually implemented as the equivalent of
+.BR O_DSYNC ).
+.P
+Since Linux 2.6.33, proper
+.B O_SYNC
+support is provided.
+However, to ensure backward binary compatibility,
+.B O_DSYNC
+was defined with the same value as the historical
+.BR O_SYNC ,
+and
+.B O_SYNC
+was defined as a new (two-bit) flag value that includes the
+.B O_DSYNC
+flag value.
+This ensures that applications compiled against
+new headers get at least
+.B O_DSYNC
+semantics before Linux 2.6.33.
+.\"
+.SS C library/kernel differences
+Since glibc 2.26,
+the glibc wrapper function for
+.BR open ()
+employs the
+.BR openat ()
+system call, rather than the kernel's
+.BR open ()
+system call.
+For certain architectures, this is also true before glibc 2.26.
+.\"
+.SH STANDARDS
+.TP
+.BR open ()
+.TQ
+.BR creat ()
+.TQ
+.BR openat ()
+POSIX.1-2008.
+.P
+.BR openat2 (2)
+Linux.
+.P
+The
+.BR O_DIRECT ,
+.BR O_NOATIME ,
+.BR O_PATH ,
+and
+.B O_TMPFILE
+flags are Linux-specific.
+One must define
+.B _GNU_SOURCE
+to obtain their definitions.
+.P
+The
+.BR O_CLOEXEC ,
+.BR O_DIRECTORY ,
+and
+.B O_NOFOLLOW
+flags are not specified in POSIX.1-2001,
+but are specified in POSIX.1-2008.
+Since glibc 2.12, one can obtain their definitions by defining either
+.B _POSIX_C_SOURCE
+with a value greater than or equal to 200809L or
+.B _XOPEN_SOURCE
+with a value greater than or equal to 700.
+In glibc 2.11 and earlier, one obtains the definitions by defining
+.BR _GNU_SOURCE .
+.SH HISTORY
+.TP
+.BR open ()
+.TQ
+.BR creat ()
+SVr4, 4.3BSD, POSIX.1-2001.
+.TP
+.BR openat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.SH NOTES
+Under Linux, the
+.B O_NONBLOCK
+flag is sometimes used in cases where one wants to open
+but does not necessarily have the intention to read or write.
+For example,
+this may be used to open a device in order to get a file descriptor
+for use with
+.BR ioctl (2).
+.P
+Note that
+.BR open ()
+can open device special files, but
+.BR creat ()
+cannot create them; use
+.BR mknod (2)
+instead.
+.P
+If the file is newly created, its
+.IR st_atime ,
+.IR st_ctime ,
+.I st_mtime
+fields
+(respectively, time of last access, time of last status change, and
+time of last modification; see
+.BR stat (2))
+are set
+to the current time, and so are the
+.I st_ctime
+and
+.I st_mtime
+fields of the
+parent directory.
+Otherwise, if the file is modified because of the
+.B O_TRUNC
+flag, its
+.I st_ctime
+and
+.I st_mtime
+fields are set to the current time.
+.P
+The files in the
+.IR /proc/ pid /fd
+directory show the open file descriptors of the process with the PID
+.IR pid .
+The files in the
+.IR /proc/ pid /fdinfo
+directory show even more information about these file descriptors.
+See
+.BR proc (5)
+for further details of both of these directories.
+.P
+The Linux header file
+.B <asm/fcntl.h>
+doesn't define
+.BR O_ASYNC ;
+the (BSD-derived)
+.B FASYNC
+synonym is defined instead.
+.\"
+.\"
+.SS Open file descriptions
+The term open file description is the one used by POSIX to refer to the
+entries in the system-wide table of open files.
+In other contexts, this object is
+variously also called an "open file object",
+a "file handle", an "open file table entry",
+or\[em]in kernel-developer parlance\[em]a
+.IR "struct file" .
+.P
+When a file descriptor is duplicated (using
+.BR dup (2)
+or similar),
+the duplicate refers to the same open file description
+as the original file descriptor,
+and the two file descriptors consequently share
+the file offset and file status flags.
+Such sharing can also occur between processes:
+a child process created via
+.BR fork (2)
+inherits duplicates of its parent's file descriptors,
+and those duplicates refer to the same open file descriptions.
+.P
+Each
+.BR open ()
+of a file creates a new open file description;
+thus, there may be multiple open file descriptions
+corresponding to a file inode.
+.P
+On Linux, one can use the
+.BR kcmp (2)
+.B KCMP_FILE
+operation to test whether two file descriptors
+(in the same process or in two different processes)
+refer to the same open file description.
+.\"
+.SS NFS
+There are many infelicities in the protocol underlying NFS, affecting
+amongst others
+.BR O_SYNC " and " O_NDELAY .
+.P
+On NFS filesystems with UID mapping enabled,
+.BR open ()
+may
+return a file descriptor but, for example,
+.BR read (2)
+requests are denied
+with
+.BR EACCES .
+This is because the client performs
+.BR open ()
+by checking the
+permissions, but UID mapping is performed by the server upon
+read and write requests.
+.\"
+.\"
+.SS FIFOs
+Opening the read or write end of a FIFO blocks until the other
+end is also opened (by another process or thread).
+See
+.BR fifo (7)
+for further details.
+.\"
+.\"
+.SS File access mode
+Unlike the other values that can be specified in
+.IR flags ,
+the
+.I "access mode"
+values
+.BR O_RDONLY ", " O_WRONLY ", and " O_RDWR
+do not specify individual bits.
+Rather, they define the low order two bits of
+.IR flags ,
+and are defined respectively as 0, 1, and 2.
+In other words, the combination
+.B "O_RDONLY | O_WRONLY"
+is a logical error, and certainly does not have the same meaning as
+.BR O_RDWR .
+.P
+Linux reserves the special, nonstandard access mode 3 (binary 11) in
+.I flags
+to mean:
+check for read and write permission on the file and return a file descriptor
+that can't be used for reading or writing.
+This nonstandard access mode is used by some Linux drivers to return a
+file descriptor that is to be used only for device-specific
+.BR ioctl (2)
+operations.
+.\" See for example util-linux's disk-utils/setfdprm.c
+.\" For some background on access mode 3, see
+.\" http://thread.gmane.org/gmane.linux.kernel/653123
+.\" "[RFC] correct flags to f_mode conversion in __dentry_open"
+.\" LKML, 12 Mar 2008
+.\"
+.\"
+.SS Rationale for openat() and other "directory file descriptor" APIs
+.BR openat ()
+and the other system calls and library functions that take
+a directory file descriptor argument
+(i.e.,
+.BR execveat (2),
+.BR faccessat (2),
+.BR fanotify_mark (2),
+.BR fchmodat (2),
+.BR fchownat (2),
+.BR fspick (2),
+.BR fstatat (2),
+.BR futimesat (2),
+.BR linkat (2),
+.BR mkdirat (2),
+.BR mknodat (2),
+.BR mount_setattr (2),
+.BR move_mount (2),
+.BR name_to_handle_at (2),
+.BR open_tree (2),
+.BR openat2 (2),
+.BR readlinkat (2),
+.BR renameat (2),
+.BR renameat2 (2),
+.BR statx (2),
+.BR symlinkat (2),
+.BR unlinkat (2),
+.BR utimensat (2),
+.BR mkfifoat (3),
+and
+.BR scandirat (3))
+address two problems with the older interfaces that preceded them.
+Here, the explanation is in terms of the
+.BR openat ()
+call, but the rationale is analogous for the other interfaces.
+.P
+First,
+.BR openat ()
+allows an application to avoid race conditions that could
+occur when using
+.BR open ()
+to open files in directories other than the current working directory.
+These race conditions result from the fact that some component
+of the directory prefix given to
+.BR open ()
+could be changed in parallel with the call to
+.BR open ().
+Suppose, for example, that we wish to create the file
+.I dir1/dir2/xxx.dep
+if the file
+.I dir1/dir2/xxx
+exists.
+The problem is that between the existence check and the file-creation step,
+.I dir1
+or
+.I dir2
+(which might be symbolic links)
+could be modified to point to a different location.
+Such races can be avoided by
+opening a file descriptor for the target directory,
+and then specifying that file descriptor as the
+.I dirfd
+argument of (say)
+.BR fstatat (2)
+and
+.BR openat ().
+The use of the
+.I dirfd
+file descriptor also has other benefits:
+.IP \[bu] 3
+the file descriptor is a stable reference to the directory,
+even if the directory is renamed; and
+.IP \[bu]
+the open file descriptor prevents the underlying filesystem from
+being dismounted,
+just as when a process has a current working directory on a filesystem.
+.P
+Second,
+.BR openat ()
+allows the implementation of a per-thread "current working
+directory", via file descriptor(s) maintained by the application.
+(This functionality can also be obtained by tricks based
+on the use of
+.IR /proc/self/fd/ dirfd,
+but less efficiently.)
+.P
+The
+.I dirfd
+argument for these APIs can be obtained by using
+.BR open ()
+or
+.BR openat ()
+to open a directory (with either the
+.B O_RDONLY
+or the
+.B O_PATH
+flag).
+Alternatively, such a file descriptor can be obtained by applying
+.BR dirfd (3)
+to a directory stream created using
+.BR opendir (3).
+.P
+When these APIs are given a
+.I dirfd
+argument of
+.B AT_FDCWD
+or the specified pathname is absolute,
+then they handle their pathname argument in the same way as
+the corresponding conventional APIs.
+However, in this case, several of the APIs have a
+.I flags
+argument that provides access to functionality that is not available with
+the corresponding conventional APIs.
+.\"
+.\"
+.SS O_DIRECT
+The
+.B O_DIRECT
+flag may impose alignment restrictions on the length and address
+of user-space buffers and the file offset of I/Os.
+In Linux alignment
+restrictions vary by filesystem and kernel version and might be
+absent entirely.
+The handling of misaligned
+.B O_DIRECT
+I/Os also varies;
+they can either fail with
+.B EINVAL
+or fall back to buffered I/O.
+.P
+Since Linux 6.1,
+.B O_DIRECT
+support and alignment restrictions for a file can be queried using
+.BR statx (2),
+using the
+.B STATX_DIOALIGN
+flag.
+Support for
+.B STATX_DIOALIGN
+varies by filesystem;
+see
+.BR statx (2).
+.P
+Some filesystems provide their own interfaces for querying
+.B O_DIRECT
+alignment restrictions,
+for example the
+.B XFS_IOC_DIOINFO
+operation in
+.BR xfsctl (3).
+.B STATX_DIOALIGN
+should be used instead when it is available.
+.P
+If none of the above is available,
+then direct I/O support and alignment restrictions
+can only be assumed from known characteristics of the filesystem,
+the individual file,
+the underlying storage device(s),
+and the kernel version.
+In Linux 2.4,
+most filesystems based on block devices require that
+the file offset and the length and memory address of all I/O segments
+be multiples of the filesystem block size
+(typically 4096 bytes).
+In Linux 2.6.0,
+this was relaxed to the logical block size of the block device
+(typically 512 bytes).
+A block device's logical block size can be determined using the
+.BR ioctl (2)
+.B BLKSSZGET
+operation or from the shell using the command:
+.P
+.in +4n
+.EX
+blockdev \-\-getss
+.EE
+.in
+.P
+.B O_DIRECT
+I/Os should never be run concurrently with the
+.BR fork (2)
+system call,
+if the memory buffer is a private mapping
+(i.e., any mapping created with the
+.BR mmap (2)
+.B MAP_PRIVATE
+flag;
+this includes memory allocated on the heap and statically allocated buffers).
+Any such I/Os, whether submitted via an asynchronous I/O interface or from
+another thread in the process,
+should be completed before
+.BR fork (2)
+is called.
+Failure to do so can result in data corruption and undefined behavior in
+parent and child processes.
+This restriction does not apply when the memory buffer for the
+.B O_DIRECT
+I/Os was created using
+.BR shmat (2)
+or
+.BR mmap (2)
+with the
+.B MAP_SHARED
+flag.
+Nor does this restriction apply when the memory buffer has been advised as
+.B MADV_DONTFORK
+with
+.BR madvise (2),
+ensuring that it will not be available
+to the child after
+.BR fork (2).
+.P
+The
+.B O_DIRECT
+flag was introduced in SGI IRIX, where it has alignment
+restrictions similar to those of Linux 2.4.
+IRIX has also a
+.BR fcntl (2)
+call to query appropriate alignments, and sizes.
+FreeBSD 4.x introduced
+a flag of the same name, but without alignment restrictions.
+.P
+.B O_DIRECT
+support was added in Linux 2.4.10.
+Older Linux kernels simply ignore this flag.
+Some filesystems may not implement the flag, in which case
+.BR open ()
+fails with the error
+.B EINVAL
+if it is used.
+.P
+Applications should avoid mixing
+.B O_DIRECT
+and normal I/O to the same file,
+and especially to overlapping byte regions in the same file.
+Even when the filesystem correctly handles the coherency issues in
+this situation, overall I/O throughput is likely to be slower than
+using either mode alone.
+Likewise, applications should avoid mixing
+.BR mmap (2)
+of files with direct I/O to the same files.
+.P
+The behavior of
+.B O_DIRECT
+with NFS will differ from local filesystems.
+Older kernels, or
+kernels configured in certain ways, may not support this combination.
+The NFS protocol does not support passing the flag to the server, so
+.B O_DIRECT
+I/O will bypass the page cache only on the client; the server may
+still cache the I/O.
+The client asks the server to make the I/O
+synchronous to preserve the synchronous semantics of
+.BR O_DIRECT .
+Some servers will perform poorly under these circumstances, especially
+if the I/O size is small.
+Some servers may also be configured to
+lie to clients about the I/O having reached stable storage; this
+will avoid the performance penalty at some risk to data integrity
+in the event of server power failure.
+The Linux NFS client places no alignment restrictions on
+.B O_DIRECT
+I/O.
+.P
+In summary,
+.B O_DIRECT
+is a potentially powerful tool that should be used with caution.
+It is recommended that applications treat use of
+.B O_DIRECT
+as a performance option which is disabled by default.
+.SH BUGS
+Currently, it is not possible to enable signal-driven
+I/O by specifying
+.B O_ASYNC
+when calling
+.BR open ();
+use
+.BR fcntl (2)
+to enable this flag.
+.\" FIXME . Check bugzilla report on open(O_ASYNC)
+.\" See http://bugzilla.kernel.org/show_bug.cgi?id=5993
+.P
+One must check for two different error codes,
+.B EISDIR
+and
+.BR ENOENT ,
+when trying to determine whether the kernel supports
+.B O_TMPFILE
+functionality.
+.P
+When both
+.B O_CREAT
+and
+.B O_DIRECTORY
+are specified in
+.I flags
+and the file specified by
+.I pathname
+does not exist,
+.BR open ()
+will create a regular file (i.e.,
+.B O_DIRECTORY
+is ignored).
+.SH SEE ALSO
+.BR chmod (2),
+.BR chown (2),
+.BR close (2),
+.BR dup (2),
+.BR fcntl (2),
+.BR link (2),
+.BR lseek (2),
+.BR mknod (2),
+.BR mmap (2),
+.BR mount (2),
+.BR open_by_handle_at (2),
+.BR openat2 (2),
+.BR read (2),
+.BR socket (2),
+.BR stat (2),
+.BR umask (2),
+.BR unlink (2),
+.BR write (2),
+.BR fopen (3),
+.BR acl (5),
+.BR fifo (7),
+.BR inode (7),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/open_by_handle_at.2 b/man/man2/open_by_handle_at.2
new file mode 100644
index 000000000..a4050d664
--- /dev/null
+++ b/man/man2/open_by_handle_at.2
@@ -0,0 +1,787 @@
+.\" Copyright (c) 2014 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH open_by_handle_at 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+name_to_handle_at, open_by_handle_at \- obtain handle
+for a pathname and open file via a handle
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <fcntl.h>
+.P
+.BI "int name_to_handle_at(int " dirfd ", const char *" pathname ,
+.BI "                      struct file_handle *" handle ,
+.BI "                      int *" mount_id ", int " flags );
+.BI "int open_by_handle_at(int " mount_fd ", struct file_handle *" handle ,
+.BI "                      int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR name_to_handle_at ()
+and
+.BR open_by_handle_at ()
+system calls split the functionality of
+.BR openat (2)
+into two parts:
+.BR name_to_handle_at ()
+returns an opaque handle that corresponds to a specified file;
+.BR open_by_handle_at ()
+opens the file corresponding to a handle returned by a previous call to
+.BR name_to_handle_at ()
+and returns an open file descriptor.
+.\"
+.\"
+.SS name_to_handle_at()
+The
+.BR name_to_handle_at ()
+system call returns a file handle and a mount ID corresponding to
+the file specified by the
+.I dirfd
+and
+.I pathname
+arguments.
+The file handle is returned via the argument
+.IR handle ,
+which is a pointer to a structure of the following form:
+.P
+.in +4n
+.EX
+struct file_handle {
+    unsigned int  handle_bytes;   /* Size of f_handle [in, out] */
+    int           handle_type;    /* Handle type [out] */
+    unsigned char f_handle[0];    /* File identifier (sized by
+                                     caller) [out] */
+};
+.EE
+.in
+.P
+It is the caller's responsibility to allocate the structure
+with a size large enough to hold the handle returned in
+.IR f_handle .
+Before the call, the
+.I handle_bytes
+field should be initialized to contain the allocated size for
+.IR f_handle .
+(The constant
+.BR MAX_HANDLE_SZ ,
+defined in
+.IR <fcntl.h> ,
+specifies the maximum expected size for a file handle.
+It is not a
+guaranteed upper limit as future filesystems may require more space.)
+Upon successful return, the
+.I handle_bytes
+field is updated to contain the number of bytes actually written to
+.IR f_handle .
+.P
+The caller can discover the required size for the
+.I file_handle
+structure by making a call in which
+.I handle\->handle_bytes
+is zero;
+in this case, the call fails with the error
+.B EOVERFLOW
+and
+.I handle\->handle_bytes
+is set to indicate the required size;
+the caller can then use this information to allocate a structure
+of the correct size (see EXAMPLES below).
+Some care is needed here as
+.B EOVERFLOW
+can also indicate that no file handle is available for this particular
+name in a filesystem which does normally support file-handle lookup.
+This case can be detected when the
+.B EOVERFLOW
+error is returned without
+.I handle_bytes
+being increased.
+.P
+Other than the use of the
+.I handle_bytes
+field, the caller should treat the
+.I file_handle
+structure as an opaque data type: the
+.I handle_type
+and
+.I f_handle
+fields can be used in a subsequent call to
+.BR open_by_handle_at ().
+The caller can also use the opaque
+.I file_handle
+to compare the identity of filesystem objects
+that were queried at different times and possibly
+at different paths.
+The
+.BR fanotify (7)
+subsystem can report events
+with an information record containing a
+.I file_handle
+to identify the filesystem object.
+.P
+The
+.I flags
+argument is a bit mask constructed by ORing together zero or more of
+.BR AT_HANDLE_FID ,
+.BR AT_EMPTY_PATH ,
+and
+.BR AT_SYMLINK_FOLLOW ,
+described below.
+.P
+When
+.I flags
+contain the
+.BR AT_HANDLE_FID " (since Linux 6.5)"
+.\" commit 96b2b072ee62be8ae68c8ecf14854c4d0505a8f8
+flag, the caller indicates that the returned
+.I file_handle
+is needed to identify the filesystem object,
+and not for opening the file later,
+so it should be expected that a subsequent call to
+.BR open_by_handle_at ()
+with the returned
+.I file_handle
+may fail.
+.P
+Together, the
+.I pathname
+and
+.I dirfd
+arguments identify the file for which a handle is to be obtained.
+There are four distinct cases:
+.IP \[bu] 3
+If
+.I pathname
+is a nonempty string containing an absolute pathname,
+then a handle is returned for the file referred to by that pathname.
+In this case,
+.I dirfd
+is ignored.
+.IP \[bu]
+If
+.I pathname
+is a nonempty string containing a relative pathname and
+.I dirfd
+has the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working directory of the caller,
+and a handle is returned for the file to which it refers.
+.IP \[bu]
+If
+.I pathname
+is a nonempty string containing a relative pathname and
+.I dirfd
+is a file descriptor referring to a directory, then
+.I pathname
+is interpreted relative to the directory referred to by
+.IR dirfd ,
+and a handle is returned for the file to which it refers.
+(See
+.BR openat (2)
+for an explanation of why "directory file descriptors" are useful.)
+.IP \[bu]
+If
+.I pathname
+is an empty string and
+.I flags
+specifies the value
+.BR AT_EMPTY_PATH ,
+then
+.I dirfd
+can be an open file descriptor referring to any type of file,
+or
+.BR AT_FDCWD ,
+meaning the current working directory,
+and a handle is returned for the file to which it refers.
+.P
+The
+.I mount_id
+argument returns an identifier for the filesystem
+mount that corresponds to
+.IR pathname .
+This corresponds to the first field in one of the records in
+.IR /proc/self/mountinfo .
+Opening the pathname in the fifth field of that record yields a file
+descriptor for the mount point;
+that file descriptor can be used in a subsequent call to
+.BR open_by_handle_at ().
+.I mount_id
+is returned both for a successful call and for a call that results
+in the error
+.BR EOVERFLOW .
+.P
+By default,
+.BR name_to_handle_at ()
+does not dereference
+.I pathname
+if it is a symbolic link, and thus returns a handle for the link itself.
+If
+.B AT_SYMLINK_FOLLOW
+is specified in
+.IR flags ,
+.I pathname
+is dereferenced if it is a symbolic link
+(so that the call returns a handle for the file referred to by the link).
+.P
+.BR name_to_handle_at ()
+does not trigger a mount when the final component of the pathname is an
+automount point.
+When a filesystem supports both file handles and
+automount points, a
+.BR name_to_handle_at ()
+call on an automount point will return with error
+.B EOVERFLOW
+without having increased
+.IR handle_bytes .
+This can happen since Linux 4.13
+.\" commit 20fa19027286983ab2734b5910c4a687436e0c31
+with NFS when accessing a directory
+which is on a separate filesystem on the server.
+In this case, the automount can be triggered by adding a "/" to the end
+of the pathname.
+.SS open_by_handle_at()
+The
+.BR open_by_handle_at ()
+system call opens the file referred to by
+.IR handle ,
+a file handle returned by a previous call to
+.BR name_to_handle_at ().
+.P
+The
+.I mount_fd
+argument is a file descriptor for any object (file, directory, etc.)
+in the mounted filesystem with respect to which
+.I handle
+should be interpreted.
+The special value
+.B AT_FDCWD
+can be specified, meaning the current working directory of the caller.
+.P
+The
+.I flags
+argument
+is as for
+.BR open (2).
+If
+.I handle
+refers to a symbolic link, the caller must specify the
+.B O_PATH
+flag, and the symbolic link is not dereferenced; the
+.B O_NOFOLLOW
+flag, if specified, is ignored.
+.P
+The caller must have the
+.B CAP_DAC_READ_SEARCH
+capability to invoke
+.BR open_by_handle_at ().
+.SH RETURN VALUE
+On success,
+.BR name_to_handle_at ()
+returns 0,
+and
+.BR open_by_handle_at ()
+returns a file descriptor (a nonnegative integer).
+.P
+In the event of an error, both system calls return \-1 and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.BR name_to_handle_at ()
+and
+.BR open_by_handle_at ()
+can fail for the same errors as
+.BR openat (2).
+In addition, they can fail with the errors noted below.
+.P
+.BR name_to_handle_at ()
+can fail with the following errors:
+.TP
+.B EFAULT
+.IR pathname ,
+.IR mount_id ,
+or
+.I handle
+points outside your accessible address space.
+.TP
+.B EINVAL
+.I flags
+includes an invalid bit value.
+.TP
+.B EINVAL
+.I handle\->handle_bytes
+is greater than
+.BR MAX_HANDLE_SZ .
+.TP
+.B ENOENT
+.I pathname
+is an empty string, but
+.B AT_EMPTY_PATH
+was not specified in
+.IR flags .
+.TP
+.B ENOTDIR
+The file descriptor supplied in
+.I dirfd
+does not refer to a directory,
+and it is not the case that both
+.I flags
+includes
+.B AT_EMPTY_PATH
+and
+.I pathname
+is an empty string.
+.TP
+.B EOPNOTSUPP
+The filesystem does not support decoding of a pathname to a file handle.
+.TP
+.B EOVERFLOW
+The
+.I handle\->handle_bytes
+value passed into the call was too small.
+When this error occurs,
+.I handle\->handle_bytes
+is updated to indicate the required size for the handle.
+.\"
+.\"
+.P
+.BR open_by_handle_at ()
+can fail with the following errors:
+.TP
+.B EBADF
+.I mount_fd
+is not an open file descriptor.
+.TP
+.B EBADF
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I handle
+points outside your accessible address space.
+.TP
+.B EINVAL
+.I handle\->handle_bytes
+is greater than
+.B MAX_HANDLE_SZ
+or is equal to zero.
+.TP
+.B ELOOP
+.I handle
+refers to a symbolic link, but
+.B O_PATH
+was not specified in
+.IR flags .
+.TP
+.B EPERM
+The caller does not have the
+.B CAP_DAC_READ_SEARCH
+capability.
+.TP
+.B ESTALE
+The specified
+.I handle
+is not valid for opening a file.
+This error will occur if, for example, the file has been deleted.
+This error can also occur if the
+.I handle
+was acquired using the
+.B AT_HANDLE_FID
+flag and the filesystem does not support
+.BR open_by_handle_at ().
+.SH VERSIONS
+FreeBSD has a broadly similar pair of system calls in the form of
+.BR getfh ()
+and
+.BR openfh ().
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.39,
+glibc 2.14.
+.SH NOTES
+A file handle can be generated in one process using
+.BR name_to_handle_at ()
+and later used in a different process that calls
+.BR open_by_handle_at ().
+.P
+Some filesystem don't support the translation of pathnames to
+file handles, for example,
+.IR /proc ,
+.IR /sys ,
+and various network filesystems.
+Some filesystems support the translation of pathnames to
+file handles, but do not support using those file handles in
+.BR open_by_handle_at ().
+.P
+A file handle may become invalid ("stale") if a file is deleted,
+or for other filesystem-specific reasons.
+Invalid handles are notified by an
+.B ESTALE
+error from
+.BR open_by_handle_at ().
+.P
+These system calls are designed for use by user-space file servers.
+For example, a user-space NFS server might generate a file handle
+and pass it to an NFS client.
+Later, when the client wants to open the file,
+it could pass the handle back to the server.
+.\" https://lwn.net/Articles/375888/
+.\"	"Open by handle" - Jonathan Corbet, 2010-02-23
+This sort of functionality allows a user-space file server to operate in
+a stateless fashion with respect to the files it serves.
+.P
+If
+.I pathname
+refers to a symbolic link and
+.I flags
+does not specify
+.BR AT_SYMLINK_FOLLOW ,
+then
+.BR name_to_handle_at ()
+returns a handle for the link (rather than the file to which it refers).
+.\" commit bcda76524cd1fa32af748536f27f674a13e56700
+The process receiving the handle can later perform operations
+on the symbolic link by converting the handle to a file descriptor using
+.BR open_by_handle_at ()
+with the
+.B O_PATH
+flag, and then passing the file descriptor as the
+.I dirfd
+argument in system calls such as
+.BR readlinkat (2)
+and
+.BR fchownat (2).
+.SS Obtaining a persistent filesystem ID
+The mount IDs in
+.I /proc/self/mountinfo
+can be reused as filesystems are unmounted and mounted.
+Therefore, the mount ID returned by
+.BR name_to_handle_at ()
+(in
+.IR *mount_id )
+should not be treated as a persistent identifier
+for the corresponding mounted filesystem.
+However, an application can use the information in the
+.I mountinfo
+record that corresponds to the mount ID
+to derive a persistent identifier.
+.P
+For example, one can use the device name in the fifth field of the
+.I mountinfo
+record to search for the corresponding device UUID via the symbolic links in
+.IR /dev/disks/by\-uuid .
+(A more comfortable way of obtaining the UUID is to use the
+.\" e.g., http://stackoverflow.com/questions/6748429/using-libblkid-to-find-uuid-of-a-partition
+.BR libblkid (3)
+library.)
+That process can then be reversed,
+using the UUID to look up the device name,
+and then obtaining the corresponding mount point,
+in order to produce the
+.I mount_fd
+argument used by
+.BR open_by_handle_at ().
+.SH EXAMPLES
+The two programs below demonstrate the use of
+.BR name_to_handle_at ()
+and
+.BR open_by_handle_at ().
+The first program
+.RI ( t_name_to_handle_at.c )
+uses
+.BR name_to_handle_at ()
+to obtain the file handle and mount ID
+for the file specified in its command-line argument;
+the handle and mount ID are written to standard output.
+.P
+The second program
+.RI ( t_open_by_handle_at.c )
+reads a mount ID and file handle from standard input.
+The program then employs
+.BR open_by_handle_at ()
+to open the file using that handle.
+If an optional command-line argument is supplied, then the
+.I mount_fd
+argument for
+.BR open_by_handle_at ()
+is obtained by opening the directory named in that argument.
+Otherwise,
+.I mount_fd
+is obtained by scanning
+.I /proc/self/mountinfo
+to find a record whose mount ID matches the mount ID
+read from standard input,
+and the mount directory specified in that record is opened.
+(These programs do not deal with the fact that mount IDs are not persistent.)
+.P
+The following shell session demonstrates the use of these two programs:
+.P
+.in +4n
+.EX
+$ \fBecho \[aq]Can you please think about it?\[aq] > cecilia.txt\fP
+$ \fB./t_name_to_handle_at cecilia.txt > fh\fP
+$ \fB./t_open_by_handle_at < fh\fP
+open_by_handle_at: Operation not permitted
+$ \fBsudo ./t_open_by_handle_at < fh\fP      # Need CAP_SYS_ADMIN
+Read 31 bytes
+$ \fBrm cecilia.txt\fP
+.EE
+.in
+.P
+Now we delete and (quickly) re-create the file so that
+it has the same content and (by chance) the same inode.
+Nevertheless,
+.BR open_by_handle_at ()
+.\" Christoph Hellwig: That's why the file handles contain a generation
+.\" counter that gets incremented in this case.
+recognizes that the original file referred to by the file handle
+no longer exists.
+.P
+.in +4n
+.EX
+$ \fBstat \-\-printf="%i\en" cecilia.txt\fP     # Display inode number
+4072121
+$ \fBrm cecilia.txt\fP
+$ \fBecho \[aq]Can you please think about it?\[aq] > cecilia.txt\fP
+$ \fBstat \-\-printf="%i\en" cecilia.txt\fP     # Check inode number
+4072121
+$ \fBsudo ./t_open_by_handle_at < fh\fP
+open_by_handle_at: Stale NFS file handle
+.EE
+.in
+.SS Program source: t_name_to_handle_at.c
+\&
+.\" SRC BEGIN (t_name_to_handle_at.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int                 mount_id, fhsize, flags, dirfd;
+    char                *pathname;
+    struct file_handle  *fhp;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s pathname\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    pathname = argv[1];
+\&
+    /* Allocate file_handle structure. */
+\&
+    fhsize = sizeof(*fhp);
+    fhp = malloc(fhsize);
+    if (fhp == NULL)
+        err(EXIT_FAILURE, "malloc");
+\&
+    /* Make an initial call to name_to_handle_at() to discover
+       the size required for file handle. */
+\&
+    dirfd = AT_FDCWD;           /* For name_to_handle_at() calls */
+    flags = 0;                  /* For name_to_handle_at() calls */
+    fhp\->handle_bytes = 0;
+    if (name_to_handle_at(dirfd, pathname, fhp,
+                          &mount_id, flags) != \-1
+        || errno != EOVERFLOW)
+    {
+        fprintf(stderr, "Unexpected result from name_to_handle_at()\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Reallocate file_handle structure with correct size. */
+\&
+    fhsize = sizeof(*fhp) + fhp\->handle_bytes;
+    fhp = realloc(fhp, fhsize);         /* Copies fhp\->handle_bytes */
+    if (fhp == NULL)
+        err(EXIT_FAILURE, "realloc");
+\&
+    /* Get file handle from pathname supplied on command line. */
+\&
+    if (name_to_handle_at(dirfd, pathname, fhp, &mount_id, flags) == \-1)
+        err(EXIT_FAILURE, "name_to_handle_at");
+\&
+    /* Write mount ID, file handle size, and file handle to stdout,
+       for later reuse by t_open_by_handle_at.c. */
+\&
+    printf("%d\en", mount_id);
+    printf("%u %d   ", fhp\->handle_bytes, fhp\->handle_type);
+    for (size_t j = 0; j < fhp\->handle_bytes; j++)
+        printf(" %02x", fhp\->f_handle[j]);
+    printf("\en");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SS Program source: t_open_by_handle_at.c
+\&
+.\" SRC BEGIN (t_open_by_handle_at.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+\&
+/* Scan /proc/self/mountinfo to find the line whose mount ID matches
+   \[aq]mount_id\[aq]. (An easier way to do this is to install and use the
+   \[aq]libmount\[aq] library provided by the \[aq]util\-linux\[aq] project.)
+   Open the corresponding mount path and return the resulting file
+   descriptor. */
+\&
+static int
+open_mount_path_by_id(int mount_id)
+{
+    int      mi_mount_id, found;
+    char     mount_path[PATH_MAX];
+    char     *linep;
+    FILE     *fp;
+    size_t   lsize;
+    ssize_t  nread;
+\&
+    fp = fopen("/proc/self/mountinfo", "r");
+    if (fp == NULL)
+        err(EXIT_FAILURE, "fopen");
+\&
+    found = 0;
+    linep = NULL;
+    while (!found) {
+        nread = getline(&linep, &lsize, fp);
+        if (nread == \-1)
+            break;
+\&
+        nread = sscanf(linep, "%d %*d %*s %*s %s",
+                       &mi_mount_id, mount_path);
+        if (nread != 2) {
+            fprintf(stderr, "Bad sscanf()\en");
+            exit(EXIT_FAILURE);
+        }
+\&
+        if (mi_mount_id == mount_id)
+            found = 1;
+    }
+    free(linep);
+\&
+    fclose(fp);
+\&
+    if (!found) {
+        fprintf(stderr, "Could not find mount point\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    return open(mount_path, O_RDONLY);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int                 mount_id, fd, mount_fd, handle_bytes;
+    char                buf[1000];
+#define LINE_SIZE 100
+    char                line1[LINE_SIZE], line2[LINE_SIZE];
+    char                *nextp;
+    ssize_t             nread;
+    struct file_handle  *fhp;
+\&
+    if ((argc > 1 && strcmp(argv[1], "\-\-help") == 0) || argc > 2) {
+        fprintf(stderr, "Usage: %s [mount\-path]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Standard input contains mount ID and file handle information:
+\&
+         Line 1: <mount_id>
+         Line 2: <handle_bytes> <handle_type>   <bytes of handle in hex>
+    */
+\&
+    if (fgets(line1, sizeof(line1), stdin) == NULL ||
+        fgets(line2, sizeof(line2), stdin) == NULL)
+    {
+        fprintf(stderr, "Missing mount_id / file handle\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    mount_id = atoi(line1);
+\&
+    handle_bytes = strtoul(line2, &nextp, 0);
+\&
+    /* Given handle_bytes, we can now allocate file_handle structure. */
+\&
+    fhp = malloc(sizeof(*fhp) + handle_bytes);
+    if (fhp == NULL)
+        err(EXIT_FAILURE, "malloc");
+\&
+    fhp\->handle_bytes = handle_bytes;
+\&
+    fhp\->handle_type = strtoul(nextp, &nextp, 0);
+\&
+    for (size_t j = 0; j < fhp\->handle_bytes; j++)
+        fhp\->f_handle[j] = strtoul(nextp, &nextp, 16);
+\&
+    /* Obtain file descriptor for mount point, either by opening
+       the pathname specified on the command line, or by scanning
+       /proc/self/mounts to find a mount that matches the \[aq]mount_id\[aq]
+       that we received from stdin. */
+\&
+    if (argc > 1)
+        mount_fd = open(argv[1], O_RDONLY);
+    else
+        mount_fd = open_mount_path_by_id(mount_id);
+\&
+    if (mount_fd == \-1)
+        err(EXIT_FAILURE, "opening mount fd");
+\&
+    /* Open file using handle and mount point. */
+\&
+    fd = open_by_handle_at(mount_fd, fhp, O_RDONLY);
+    if (fd == \-1)
+        err(EXIT_FAILURE, "open_by_handle_at");
+\&
+    /* Try reading a few bytes from the file. */
+\&
+    nread = read(fd, buf, sizeof(buf));
+    if (nread == \-1)
+        err(EXIT_FAILURE, "read");
+\&
+    printf("Read %zd bytes\en", nread);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR open (2),
+.BR libblkid (3),
+.BR blkid (8),
+.BR findfs (8),
+.BR mount (8)
+.P
+The
+.I libblkid
+and
+.I libmount
+documentation in the latest
+.I util\-linux
+release at
+.UR https://www.kernel.org/pub/linux/utils/util\-linux/
+.UE
diff --git a/man/man2/openat.2 b/man/man2/openat.2
new file mode 100644
index 000000000..604e1213a
--- /dev/null
+++ b/man/man2/openat.2
@@ -0,0 +1 @@
+.so man2/open.2
diff --git a/man/man2/openat2.2 b/man/man2/openat2.2
new file mode 100644
index 000000000..e2a11162d
--- /dev/null
+++ b/man/man2/openat2.2
@@ -0,0 +1,582 @@
+.\" Copyright (C) 2019 Aleksa Sarai <cyphar@cyphar.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH openat2 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+openat2 \- open and possibly create a file (extended)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" \
+"          /* Definition of " O_* " and " S_* " constants */"
+.BR "#include <linux/openat2.h>" "  /* Definition of " RESOLVE_* " constants */"
+.BR "#include <sys/syscall.h>" "    /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(SYS_openat2, int " dirfd ", const char *" pathname ,
+.BI "             struct open_how *" how ", size_t " size );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR openat2 (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR openat2 ()
+system call is an extension of
+.BR openat (2)
+and provides a superset of its functionality.
+.P
+The
+.BR openat2 ()
+system call opens the file specified by
+.IR pathname .
+If the specified file does not exist, it may optionally (if
+.B O_CREAT
+is specified in
+.IR how.flags )
+be created.
+.P
+As with
+.BR openat (2),
+if
+.I pathname
+is a relative pathname, then it is interpreted relative to the
+directory referred to by the file descriptor
+.I dirfd
+(or the current working directory of the calling process, if
+.I dirfd
+is the special value
+.BR AT_FDCWD ).
+If
+.I pathname
+is an absolute pathname, then
+.I dirfd
+is ignored (unless
+.I how.resolve
+contains
+.BR RESOLVE_IN_ROOT ,
+in which case
+.I pathname
+is resolved relative to
+.IR dirfd ).
+.P
+Rather than taking a single
+.I flags
+argument, an extensible structure (\fIhow\fP) is passed to allow for
+future extensions.
+The
+.I size
+argument must be specified as
+.IR "sizeof(struct open_how)" .
+.\"
+.SS The open_how structure
+The
+.I how
+argument specifies how
+.I pathname
+should be opened, and acts as a superset of the
+.I flags
+and
+.I mode
+arguments to
+.BR openat (2).
+This argument is a pointer to an
+.I open_how
+structure,
+described in
+.BR open_how (2type).
+.P
+Any future extensions to
+.BR openat2 ()
+will be implemented as new fields appended to the
+.I open_how
+structure,
+with a zero value in a new field resulting in the kernel behaving
+as though that extension field was not present.
+Therefore, the caller
+.I must
+zero-fill this structure on
+initialization.
+(See the "Extensibility" section of the
+.B NOTES
+for more detail on why this is necessary.)
+.P
+The fields of the
+.I open_how
+structure are as follows:
+.TP
+.I flags
+This field specifies
+the file creation and file status flags to use when opening the file.
+All of the
+.B O_*
+flags defined for
+.BR openat (2)
+are valid
+.BR openat2 ()
+flag values.
+.IP
+Whereas
+.BR openat (2)
+ignores unknown bits in its
+.I flags
+argument,
+.BR openat2 ()
+returns an error if unknown or conflicting flags are specified in
+.IR how.flags .
+.TP
+.I mode
+This field specifies the
+mode for the new file, with identical semantics to the
+.I mode
+argument of
+.BR openat (2).
+.IP
+Whereas
+.BR openat (2)
+ignores bits other than those in the range
+.I 07777
+in its
+.I mode
+argument,
+.BR openat2 ()
+returns an error if
+.I how.mode
+contains bits other than
+.IR 07777 .
+Similarly, an error is returned if
+.BR openat2 ()
+is called with a nonzero
+.I how.mode
+and
+.I how.flags
+does not contain
+.B O_CREAT
+or
+.BR O_TMPFILE .
+.TP
+.I resolve
+This is a bit-mask of flags that modify the way in which
+.B all
+components of
+.I pathname
+will be resolved.
+(See
+.BR path_resolution (7)
+for background information.)
+.IP
+The primary use case for these flags is to allow trusted programs to restrict
+how untrusted paths (or paths inside untrusted directories) are resolved.
+The full list of
+.I resolve
+flags is as follows:
+.RS
+.TP
+.B RESOLVE_BENEATH
+.\" commit adb21d2b526f7f196b2f3fdca97d80ba05dd14a0
+Do not permit the path resolution to succeed if any component of the resolution
+is not a descendant of the directory indicated by
+.IR dirfd .
+This causes absolute symbolic links (and absolute values of
+.IR pathname )
+to be rejected.
+.IP
+Currently, this flag also disables magic-link resolution (see below).
+However, this may change in the future.
+Therefore, to ensure that magic links are not resolved,
+the caller should explicitly specify
+.BR RESOLVE_NO_MAGICLINKS .
+.TP
+.B RESOLVE_IN_ROOT
+.\" commit 8db52c7e7ee1bd861b6096fcafc0fe7d0f24a994
+Treat the directory referred to by
+.I dirfd
+as the root directory while resolving
+.IR pathname .
+Absolute symbolic links are interpreted relative to
+.IR dirfd .
+If a prefix component of
+.I pathname
+equates to
+.IR dirfd ,
+then an immediately following
+.I ..\&
+component likewise equates to
+.I dirfd
+(just as
+.I /..\&
+is traditionally equivalent to
+.IR / ).
+If
+.I pathname
+is an absolute path, it is also interpreted relative to
+.IR dirfd .
+.IP
+The effect of this flag is as though the calling process had used
+.BR chroot (2)
+to (temporarily) modify its root directory (to the directory
+referred to by
+.IR dirfd ).
+However, unlike
+.BR chroot (2)
+(which changes the filesystem root permanently for a process),
+.B RESOLVE_IN_ROOT
+allows a program to efficiently restrict path resolution on a per-open basis.
+.IP
+Currently, this flag also disables magic-link resolution.
+However, this may change in the future.
+Therefore, to ensure that magic links are not resolved,
+the caller should explicitly specify
+.BR RESOLVE_NO_MAGICLINKS .
+.TP
+.B RESOLVE_NO_MAGICLINKS
+.\" commit 278121417a72d87fb29dd8c48801f80821e8f75a
+Disallow all magic-link resolution during path resolution.
+.IP
+Magic links are symbolic link-like objects that are most notably found in
+.BR proc (5);
+examples include
+.IR /proc/ pid /exe
+and
+.IR /proc/ pid /fd/* .
+(See
+.BR symlink (7)
+for more details.)
+.IP
+Unknowingly opening magic links can be risky for some applications.
+Examples of such risks include the following:
+.RS
+.IP \[bu] 3
+If the process opening a pathname is a controlling process that
+currently has no controlling terminal (see
+.BR credentials (7)),
+then opening a magic link inside
+.IR /proc/ pid /fd
+that happens to refer to a terminal
+would cause the process to acquire a controlling terminal.
+.IP \[bu]
+.\" From https://lwn.net/Articles/796868/:
+.\"     The presence of this flag will prevent a path lookup operation
+.\"     from traversing through one of these magic links, thus blocking
+.\"     (for example) attempts to escape from a container via a /proc
+.\"     entry for an open file descriptor.
+In a containerized environment,
+a magic link inside
+.I /proc
+may refer to an object outside the container,
+and thus may provide a means to escape from the container.
+.RE
+.IP
+Because of such risks,
+an application may prefer to disable magic link resolution using the
+.B RESOLVE_NO_MAGICLINKS
+flag.
+.IP
+If the trailing component (i.e., basename) of
+.I pathname
+is a magic link,
+.I how.resolve
+contains
+.BR RESOLVE_NO_MAGICLINKS ,
+and
+.I how.flags
+contains both
+.B O_PATH
+and
+.BR O_NOFOLLOW ,
+then an
+.B O_PATH
+file descriptor referencing the magic link will be returned.
+.TP
+.B RESOLVE_NO_SYMLINKS
+.\" commit 278121417a72d87fb29dd8c48801f80821e8f75a
+Disallow resolution of symbolic links during path resolution.
+This option implies
+.BR RESOLVE_NO_MAGICLINKS .
+.IP
+If the trailing component (i.e., basename) of
+.I pathname
+is a symbolic link,
+.I how.resolve
+contains
+.BR RESOLVE_NO_SYMLINKS ,
+and
+.I how.flags
+contains both
+.B O_PATH
+and
+.BR O_NOFOLLOW ,
+then an
+.B O_PATH
+file descriptor referencing the symbolic link will be returned.
+.IP
+Note that the effect of the
+.B RESOLVE_NO_SYMLINKS
+flag,
+which affects the treatment of symbolic links in all of the components of
+.IR pathname ,
+differs from the effect of the
+.B O_NOFOLLOW
+file creation flag (in
+.IR how.flags ),
+which affects the handling of symbolic links only in the final component of
+.IR pathname .
+.IP
+Applications that employ the
+.B RESOLVE_NO_SYMLINKS
+flag are encouraged to make its use configurable
+(unless it is used for a specific security purpose),
+as symbolic links are very widely used by end-users.
+Setting this flag indiscriminately\[em]i.e.,
+for purposes not specifically related to security\[em]for all uses of
+.BR openat2 ()
+may result in spurious errors on previously functional systems.
+This may occur if, for example,
+a system pathname that is used by an application is modified
+(e.g., in a new distribution release)
+so that a pathname component (now) contains a symbolic link.
+.TP
+.B RESOLVE_NO_XDEV
+.\" commit 72ba29297e1439efaa54d9125b866ae9d15df339
+Disallow traversal of mount points during path resolution (including all bind
+mounts).
+Consequently,
+.I pathname
+must either be on the same mount as the directory referred to by
+.IR dirfd ,
+or on the same mount as the current working directory if
+.I dirfd
+is specified as
+.BR AT_FDCWD .
+.IP
+Applications that employ the
+.B RESOLVE_NO_XDEV
+flag are encouraged to make its use configurable (unless it is
+used for a specific security purpose),
+as bind mounts are widely used by end-users.
+Setting this flag indiscriminately\[em]i.e.,
+for purposes not specifically related to security\[em]for all uses of
+.BR openat2 ()
+may result in spurious errors on previously functional systems.
+This may occur if, for example,
+a system pathname that is used by an application is modified
+(e.g., in a new distribution release)
+so that a pathname component (now) contains a bind mount.
+.TP
+.B RESOLVE_CACHED
+Make the open operation fail unless all path components are already present
+in the kernel's lookup cache.
+If any kind of revalidation or I/O is needed to satisfy the lookup,
+.BR openat2 ()
+fails with the error
+.BR EAGAIN .
+This is useful in providing a fast-path open that can be performed without
+resorting to thread offload, or other mechanisms that an application might
+use to offload slower operations.
+.RE
+.IP
+If any bits other than those listed above are set in
+.IR how.resolve ,
+an error is returned.
+.SH RETURN VALUE
+On success, a new file descriptor is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The set of errors returned by
+.BR openat2 ()
+includes all of the errors returned by
+.BR openat (2),
+as well as the following additional errors:
+.TP
+.B E2BIG
+An extension that this kernel does not support was specified in
+.IR how .
+(See the "Extensibility" section of
+.B NOTES
+for more detail on how extensions are handled.)
+.TP
+.B EAGAIN
+.I how.resolve
+contains either
+.B RESOLVE_IN_ROOT
+or
+.BR RESOLVE_BENEATH ,
+and the kernel could not ensure that a ".." component didn't escape (due to a
+race condition or potential attack).
+The caller may choose to retry the
+.BR openat2 ()
+call.
+.TP
+.B EAGAIN
+.B RESOLVE_CACHED
+was set, and the open operation cannot be performed using only cached
+information.
+The caller should retry without
+.B RESOLVE_CACHED
+set in
+.IR how.resolve .
+.TP
+.B EINVAL
+An unknown flag or invalid value was specified in
+.IR how .
+.TP
+.B EINVAL
+.I mode
+is nonzero, but
+.I how.flags
+does not contain
+.B O_CREAT
+or
+.BR O_TMPFILE .
+.TP
+.B EINVAL
+.I size
+was smaller than any known version of
+.IR "struct open_how" .
+.TP
+.B ELOOP
+.I how.resolve
+contains
+.BR RESOLVE_NO_SYMLINKS ,
+and one of the path components was a symbolic link (or magic link).
+.TP
+.B ELOOP
+.I how.resolve
+contains
+.BR RESOLVE_NO_MAGICLINKS ,
+and one of the path components was a magic link.
+.TP
+.B EXDEV
+.I how.resolve
+contains either
+.B RESOLVE_IN_ROOT
+or
+.BR RESOLVE_BENEATH ,
+and an escape from the root during path resolution was detected.
+.TP
+.B EXDEV
+.I how.resolve
+contains
+.BR RESOLVE_NO_XDEV ,
+and a path component crosses a mount point.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.6.
+.\" commit fddb5d430ad9fa91b49b1d34d0202ffe2fa0e179
+.P
+The semantics of
+.B RESOLVE_BENEATH
+were modeled after FreeBSD's
+.BR O_BENEATH .
+.SH NOTES
+.SS Extensibility
+In order to allow for future extensibility,
+.BR openat2 ()
+requires the user-space application to specify the size of the
+.I open_how
+structure that it is passing.
+By providing this information, it is possible for
+.BR openat2 ()
+to provide both forwards- and backwards-compatibility, with
+.I size
+acting as an implicit version number.
+(Because new extension fields will always
+be appended, the structure size will always increase.)
+This extensibility design is very similar to other system calls such as
+.BR sched_setattr (2),
+.BR perf_event_open (2),
+and
+.BR clone3 (2).
+.P
+If we let
+.I usize
+be the size of the structure as specified by the user-space application, and
+.I ksize
+be the size of the structure which the kernel supports, then there are
+three cases to consider:
+.IP \[bu] 3
+If
+.I ksize
+equals
+.IR usize ,
+then there is no version mismatch and
+.I how
+can be used verbatim.
+.IP \[bu]
+If
+.I ksize
+is larger than
+.IR usize ,
+then there are some extension fields that the kernel supports
+which the user-space application
+is unaware of.
+Because a zero value in any added extension field signifies a no-op,
+the kernel
+treats all of the extension fields not provided by the user-space application
+as having zero values.
+This provides backwards-compatibility.
+.IP \[bu]
+If
+.I ksize
+is smaller than
+.IR usize ,
+then there are some extension fields which the user-space application
+is aware of but which the kernel does not support.
+Because any extension field must have its zero values signify a no-op,
+the kernel can
+safely ignore the unsupported extension fields if they are all-zero.
+If any unsupported extension fields are nonzero, then \-1 is returned and
+.I errno
+is set to
+.BR E2BIG .
+This provides forwards-compatibility.
+.P
+Because the definition of
+.I struct open_how
+may change in the future (with new fields being added when system headers are
+updated), user-space applications should zero-fill
+.I struct open_how
+to ensure that recompiling the program with new headers will not result in
+spurious errors at run time.
+The simplest way is to use a designated
+initializer:
+.P
+.in +4n
+.EX
+struct open_how how = { .flags = O_RDWR,
+                        .resolve = RESOLVE_IN_ROOT };
+.EE
+.in
+.P
+or explicitly using
+.BR memset (3)
+or similar:
+.P
+.in +4n
+.EX
+struct open_how how;
+memset(&how, 0, sizeof(how));
+how.flags = O_RDWR;
+how.resolve = RESOLVE_IN_ROOT;
+.EE
+.in
+.P
+A user-space application that wishes to determine which extensions
+the running kernel supports can do so by conducting a binary search on
+.I size
+with a structure which has every byte nonzero (to find the largest value
+which doesn't produce an error of
+.BR E2BIG ).
+.SH SEE ALSO
+.BR openat (2),
+.BR open_how (2type),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/outb.2 b/man/man2/outb.2
new file mode 100644
index 000000000..6f76d7725
--- /dev/null
+++ b/man/man2/outb.2
@@ -0,0 +1,84 @@
+.\" Copyright (c) 1995 Paul Gortmaker
+.\" (gpg109@rsphy1.anu.edu.au)
+.\" Wed Nov 29 10:58:54 EST 1995
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH outb 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+outb, outw, outl, outsb, outsw, outsl,
+inb, inw, inl, insb, insw, insl,
+outb_p, outw_p, outl_p, inb_p, inw_p, inl_p \- port I/O
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/io.h>
+.P
+.BI "unsigned char inb(unsigned short " port );
+.BI "unsigned char inb_p(unsigned short " port );
+.BI "unsigned short inw(unsigned short " port );
+.BI "unsigned short inw_p(unsigned short " port );
+.BI "unsigned int inl(unsigned short " port );
+.BI "unsigned int inl_p(unsigned short " port );
+.P
+.BI "void outb(unsigned char " value ", unsigned short " port );
+.BI "void outb_p(unsigned char " value ", unsigned short " port );
+.BI "void outw(unsigned short " value ", unsigned short " port );
+.BI "void outw_p(unsigned short " value ", unsigned short " port );
+.BI "void outl(unsigned int " value ", unsigned short " port );
+.BI "void outl_p(unsigned int " value ", unsigned short " port );
+.P
+.BI "void insb(unsigned short " port ", void " addr [. count ],
+.BI "           unsigned long " count );
+.BI "void insw(unsigned short " port ", void " addr [. count ],
+.BI "           unsigned long " count );
+.BI "void insl(unsigned short " port ", void " addr [. count ],
+.BI "           unsigned long " count );
+.BI "void outsb(unsigned short " port ", const void " addr [. count ],
+.BI "           unsigned long " count );
+.BI "void outsw(unsigned short " port ", const void " addr [. count ],
+.BI "           unsigned long " count );
+.BI "void outsl(unsigned short " port ", const void " addr [. count ],
+.BI "           unsigned long " count );
+.fi
+.SH DESCRIPTION
+This family of functions is used to do low-level port input and output.
+The out* functions do port output, the in* functions do port input;
+the b-suffix functions are byte-width and the w-suffix functions
+word-width; the _p-suffix functions pause until the I/O completes.
+.P
+They are primarily designed for internal kernel use,
+but can be used from user space.
+.\" , given the following information
+.\" in addition to that given in
+.\" .BR outb (9).
+.P
+You must compile with \fB\-O\fP or \fB\-O2\fP or similar.
+The functions
+are defined as inline macros, and will not be substituted in without
+optimization enabled, causing unresolved references at link time.
+.P
+You use
+.BR ioperm (2)
+or alternatively
+.BR iopl (2)
+to tell the kernel to allow the user space application to access the
+I/O ports in question.
+Failure to do this will cause the application
+to receive a segmentation fault.
+.SH VERSIONS
+.BR outb ()
+and friends are hardware-specific.
+The
+.I value
+argument is passed first and the
+.I port
+argument is passed second,
+which is the opposite order from most DOS implementations.
+.SH STANDARDS
+None.
+.SH SEE ALSO
+.BR ioperm (2),
+.BR iopl (2)
diff --git a/man/man2/outb_p.2 b/man/man2/outb_p.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outb_p.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/outl.2 b/man/man2/outl.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outl.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/outl_p.2 b/man/man2/outl_p.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outl_p.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/outsb.2 b/man/man2/outsb.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outsb.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/outsl.2 b/man/man2/outsl.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outsl.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/outsw.2 b/man/man2/outsw.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outsw.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/outw.2 b/man/man2/outw.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outw.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/outw_p.2 b/man/man2/outw_p.2
new file mode 100644
index 000000000..2c63c7549
--- /dev/null
+++ b/man/man2/outw_p.2
@@ -0,0 +1 @@
+.so man2/outb.2
diff --git a/man/man2/pause.2 b/man/man2/pause.2
new file mode 100644
index 000000000..f8f07f8ea
--- /dev/null
+++ b/man/man2/pause.2
@@ -0,0 +1,50 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt (michael@moria.de)
+.\" Modified Sat Jul 24 14:48:00 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995 by Mike Battersby (mib@deakin.edu.au)
+.\" Modified 2000 by aeb, following Michael Kerrisk
+.\"
+.TH pause 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pause \- wait for signal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B int pause(void);
+.fi
+.SH DESCRIPTION
+.BR pause ()
+causes the calling process (or thread) to sleep
+until a signal is delivered that either terminates the process or causes
+the invocation of a signal-catching function.
+.SH RETURN VALUE
+.BR pause ()
+returns only when a signal was caught and the
+signal-catching function returned.
+In this case,
+.BR pause ()
+returns \-1, and
+.I errno
+is set to
+.\" .BR ERESTARTNOHAND .
+.BR EINTR .
+.SH ERRORS
+.TP
+.B EINTR
+a signal was caught and the signal-catching function returned.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR kill (2),
+.BR select (2),
+.BR signal (2),
+.BR sigsuspend (2)
diff --git a/man/man2/pciconfig_iobase.2 b/man/man2/pciconfig_iobase.2
new file mode 100644
index 000000000..5ab299588
--- /dev/null
+++ b/man/man2/pciconfig_iobase.2
@@ -0,0 +1 @@
+.so man2/pciconfig_read.2
diff --git a/man/man2/pciconfig_read.2 b/man/man2/pciconfig_read.2
new file mode 100644
index 000000000..06da7a6a1
--- /dev/null
+++ b/man/man2/pciconfig_read.2
@@ -0,0 +1,122 @@
+.\" Contributed by Niki A. Rahimi, LTC Security Development
+.\" narahimi@us.ibm.com
+.\"
+.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE)
+.\" May be freely distributed and modified.
+.\" %%%LICENSE_END
+.\"
+.TH pciconfig_read 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pciconfig_read, pciconfig_write, pciconfig_iobase \-
+pci device information handling
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <pci.h>
+.P
+.BI "int pciconfig_read(unsigned long " bus ", unsigned long " dfn ,
+.BI "                   unsigned long " off ", unsigned long " len ,
+.BI "                   unsigned char *" buf );
+.BI "int pciconfig_write(unsigned long " bus ", unsigned long " dfn ,
+.BI "                   unsigned long " off ", unsigned long " len ,
+.BI "                   unsigned char *" buf );
+.BI "int pciconfig_iobase(int " which ", unsigned long " bus ,
+.BI "                   unsigned long " devfn );
+.fi
+.SH DESCRIPTION
+Most of the interaction with PCI devices is already handled by the
+kernel PCI layer,
+and thus these calls should not normally need to be accessed from user space.
+.TP
+.BR pciconfig_read ()
+Reads to
+.I buf
+from device
+.I dev
+at offset
+.I off
+value.
+.TP
+.BR pciconfig_write ()
+Writes from
+.I buf
+to device
+.I dev
+at offset
+.I off
+value.
+.TP
+.BR pciconfig_iobase ()
+You pass it a bus/devfn pair and get a physical address for either the
+memory offset (for things like prep, this is 0xc0000000),
+the IO base for PIO cycles, or the ISA holes if any.
+.SH RETURN VALUE
+.TP
+.BR pciconfig_read ()
+On success, zero is returned.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.TP
+.BR pciconfig_write ()
+On success, zero is returned.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.TP
+.BR pciconfig_iobase ()
+Returns information on locations of various I/O
+regions in physical memory according to the
+.I which
+value.
+Values for
+.I which
+are:
+.BR IOBASE_BRIDGE_NUMBER ,
+.BR IOBASE_MEMORY ,
+.BR IOBASE_IO ,
+.BR IOBASE_ISA_IO ,
+.BR IOBASE_ISA_MEM .
+.SH ERRORS
+.TP
+.B EINVAL
+.I len
+value is invalid.
+This does not apply to
+.BR pciconfig_iobase ().
+.TP
+.B EIO
+I/O error.
+.TP
+.B ENODEV
+For
+.BR pciconfig_iobase (),
+"hose" value is NULL.
+For the other calls, could not find a slot.
+.TP
+.B ENOSYS
+The system has not implemented these calls
+.RB ( CONFIG_PCI
+not defined).
+.TP
+.B EOPNOTSUPP
+This return value is valid only for
+.BR pciconfig_iobase ().
+It is returned if the value for
+.I which
+is invalid.
+.TP
+.B EPERM
+User does not have the
+.B CAP_SYS_ADMIN
+capability.
+This does not apply to
+.BR pciconfig_iobase ().
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.0.26/2.1.11.
+.SH SEE ALSO
+.BR capabilities (7)
diff --git a/man/man2/pciconfig_write.2 b/man/man2/pciconfig_write.2
new file mode 100644
index 000000000..5ab299588
--- /dev/null
+++ b/man/man2/pciconfig_write.2
@@ -0,0 +1 @@
+.so man2/pciconfig_read.2
diff --git a/man/man2/perf_event_open.2 b/man/man2/perf_event_open.2
new file mode 100644
index 000000000..5f68f5204
--- /dev/null
+++ b/man/man2/perf_event_open.2
@@ -0,0 +1,4036 @@
+.\" Copyright (c) 2012, Vincent Weaver
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" This document is based on the perf_event.h header file, the
+.\" tools/perf/design.txt file, and a lot of bitter experience.
+.\"
+.TH perf_event_open 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+perf_event_open \- set up performance monitoring
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/perf_event.h>" "    /* Definition of " PERF_* " constants */"
+.BR "#include <linux/hw_breakpoint.h>" " /* Definition of " HW_* " constants */"
+.BR "#include <sys/syscall.h>" "         /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_perf_event_open, struct perf_event_attr *" attr ,
+.BI "            pid_t " pid ", int " cpu ", int " group_fd \
+", unsigned long " flags  );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR perf_event_open (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+Given a list of parameters,
+.BR perf_event_open ()
+returns a file descriptor, for use in subsequent system calls
+(\c
+.BR read (2),
+.BR mmap (2),
+.BR prctl (2),
+.BR fcntl (2),
+etc.).
+.PP
+A call to
+.BR perf_event_open ()
+creates a file descriptor that allows measuring performance
+information.
+Each file descriptor corresponds to one
+event that is measured; these can be grouped together
+to measure multiple events simultaneously.
+.P
+Events can be enabled and disabled in two ways: via
+.BR ioctl (2)
+and via
+.BR prctl (2).
+When an event is disabled it does not count or generate overflows but does
+continue to exist and maintain its count value.
+.P
+Events come in two flavors: counting and sampled.
+A
+.I counting
+event is one that is used for counting the aggregate number of events
+that occur.
+In general, counting event results are gathered with a
+.BR read (2)
+call.
+A
+.I sampling
+event periodically writes measurements to a buffer that can then
+be accessed via
+.BR mmap (2).
+.SS Arguments
+The
+.I pid
+and
+.I cpu
+arguments allow specifying which process and CPU to monitor:
+.TP
+.BR "pid == 0" " and " "cpu == \-1"
+This measures the calling process/thread on any CPU.
+.TP
+.BR "pid == 0" " and " "cpu >= 0"
+This measures the calling process/thread only
+when running on the specified CPU.
+.TP
+.BR "pid > 0" " and " "cpu == \-1"
+This measures the specified process/thread on any CPU.
+.TP
+.BR "pid > 0" " and " "cpu >= 0"
+This measures the specified process/thread only
+when running on the specified CPU.
+.TP
+.BR "pid == \-1" " and " "cpu >= 0"
+This measures all processes/threads on the specified CPU.
+This requires
+.B CAP_PERFMON
+(since Linux 5.8) or
+.B CAP_SYS_ADMIN
+capability or a
+.I /proc/sys/kernel/perf_event_paranoid
+value of less than 1.
+.TP
+.BR "pid == \-1" " and " "cpu == \-1"
+This setting is invalid and will return an error.
+.P
+When
+.I pid
+is greater than zero, permission to perform this system call
+is governed by
+.B CAP_PERFMON
+(since Linux 5.9) and a ptrace access mode
+.B PTRACE_MODE_READ_REALCREDS
+check on older Linux versions; see
+.BR ptrace (2).
+.P
+The
+.I group_fd
+argument allows event groups to be created.
+An event group has one event which is the group leader.
+The leader is created first, with
+.IR group_fd " = \-1."
+The rest of the group members are created with subsequent
+.BR perf_event_open ()
+calls with
+.I group_fd
+being set to the file descriptor of the group leader.
+(A single event on its own is created with
+.IR group_fd " = \-1"
+and is considered to be a group with only 1 member.)
+An event group is scheduled onto the CPU as a unit:
+it will be put onto the CPU
+only if all of the events in the group can be put onto the CPU.
+This means that the values of the member events can be meaningfully compared
+\[em]added, divided (to get ratios), and so on\[em]
+with each other,
+since they have counted events for the same set of executed instructions.
+.P
+The
+.I flags
+argument is formed by ORing together zero or more of the following values:
+.TP
+.BR PERF_FLAG_FD_CLOEXEC " (since Linux 3.14)"
+.\" commit a21b0b354d4ac39be691f51c53562e2c24443d9e
+This flag enables the close-on-exec flag for the created
+event file descriptor,
+so that the file descriptor is automatically closed on
+.BR execve (2).
+Setting the close-on-exec flags at creation time, rather than later with
+.BR fcntl (2),
+avoids potential race conditions where the calling thread invokes
+.BR perf_event_open ()
+and
+.BR fcntl (2)
+at the same time as another thread calls
+.BR fork (2)
+then
+.BR execve (2).
+.TP
+.B PERF_FLAG_FD_NO_GROUP
+This flag tells the event to ignore the
+.I group_fd
+parameter except for the purpose of setting up output redirection
+using the
+.B PERF_FLAG_FD_OUTPUT
+flag.
+.TP
+.BR PERF_FLAG_FD_OUTPUT " (broken since Linux 2.6.35)"
+.\" commit ac9721f3f54b27a16c7e1afb2481e7ee95a70318
+This flag re-routes the event's sampled output to instead
+be included in the mmap buffer of the event specified by
+.IR group_fd .
+.TP
+.BR PERF_FLAG_PID_CGROUP " (since Linux 2.6.39)"
+.\" commit e5d1367f17ba6a6fed5fd8b74e4d5720923e0c25
+This flag activates per-container system-wide monitoring.
+A container
+is an abstraction that isolates a set of resources for finer-grained
+control (CPUs, memory, etc.).
+In this mode, the event is measured
+only if the thread running on the monitored CPU belongs to the designated
+container (cgroup).
+The cgroup is identified by passing a file descriptor
+opened on its directory in the cgroupfs filesystem.
+For instance, if the
+cgroup to monitor is called
+.IR test ,
+then a file descriptor opened on
+.I /dev/cgroup/test
+(assuming cgroupfs is mounted on
+.IR /dev/cgroup )
+must be passed as the
+.I pid
+parameter.
+cgroup monitoring is available only
+for system-wide events and may therefore require extra permissions.
+.P
+The
+.I perf_event_attr
+structure provides detailed configuration information
+for the event being created.
+.P
+.in +4n
+.EX
+struct perf_event_attr {
+    __u32 type;                 /* Type of event */
+    __u32 size;                 /* Size of attribute structure */
+    __u64 config;               /* Type\-specific configuration */
+\&
+    union {
+        __u64 sample_period;    /* Period of sampling */
+        __u64 sample_freq;      /* Frequency of sampling */
+    };
+\&
+    __u64 sample_type;  /* Specifies values included in sample */
+    __u64 read_format;  /* Specifies values returned in read */
+\&
+    __u64 disabled       : 1,   /* off by default */
+          inherit        : 1,   /* children inherit it */
+          pinned         : 1,   /* must always be on PMU */
+          exclusive      : 1,   /* only group on PMU */
+          exclude_user   : 1,   /* don\[aq]t count user */
+          exclude_kernel : 1,   /* don\[aq]t count kernel */
+          exclude_hv     : 1,   /* don\[aq]t count hypervisor */
+          exclude_idle   : 1,   /* don\[aq]t count when idle */
+          mmap           : 1,   /* include mmap data */
+          comm           : 1,   /* include comm data */
+          freq           : 1,   /* use freq, not period */
+          inherit_stat   : 1,   /* per task counts */
+          enable_on_exec : 1,   /* next exec enables */
+          task           : 1,   /* trace fork/exit */
+          watermark      : 1,   /* wakeup_watermark */
+          precise_ip     : 2,   /* skid constraint */
+          mmap_data      : 1,   /* non\-exec mmap data */
+          sample_id_all  : 1,   /* sample_type all events */
+          exclude_host   : 1,   /* don\[aq]t count in host */
+          exclude_guest  : 1,   /* don\[aq]t count in guest */
+          exclude_callchain_kernel : 1,
+                                /* exclude kernel callchains */
+          exclude_callchain_user   : 1,
+                                /* exclude user callchains */
+          mmap2          :  1,  /* include mmap with inode data */
+          comm_exec      :  1,  /* flag comm events that are
+                                   due to exec */
+          use_clockid    :  1,  /* use clockid for time fields */
+          context_switch :  1,  /* context switch data */
+          write_backward :  1,  /* Write ring buffer from end
+                                   to beginning */
+          namespaces     :  1,  /* include namespaces data */
+          ksymbol        :  1,  /* include ksymbol events */
+          bpf_event      :  1,  /* include bpf events */
+          aux_output     :  1,  /* generate AUX records
+                                   instead of events */
+          cgroup         :  1,  /* include cgroup events */
+          text_poke      :  1,  /* include text poke events */
+          build_id       :  1,  /* use build id in mmap2 events */
+          inherit_thread :  1,  /* children only inherit */
+                                /* if cloned with CLONE_THREAD */
+          remove_on_exec :  1,  /* event is removed from task
+                                   on exec */
+          sigtrap        :  1,  /* send synchronous SIGTRAP
+                                   on event */
+\&
+          __reserved_1   : 26;
+\&
+    union {
+        __u32 wakeup_events;    /* wakeup every n events */
+        __u32 wakeup_watermark; /* bytes before wakeup */
+    };
+\&
+    __u32     bp_type;          /* breakpoint type */
+\&
+    union {
+        __u64 bp_addr;          /* breakpoint address */
+        __u64 kprobe_func;      /* for perf_kprobe */
+        __u64 uprobe_path;      /* for perf_uprobe */
+        __u64 config1;          /* extension of config */
+    };
+\&
+    union {
+        __u64 bp_len;           /* breakpoint length */
+        __u64 kprobe_addr;      /* with kprobe_func == NULL */
+        __u64 probe_offset;     /* for perf_[k,u]probe */
+        __u64 config2;          /* extension of config1 */
+    };
+    __u64 branch_sample_type;   /* enum perf_branch_sample_type */
+    __u64 sample_regs_user;     /* user regs to dump on samples */
+    __u32 sample_stack_user;    /* size of stack to dump on
+                                   samples */
+    __s32 clockid;              /* clock to use for time fields */
+    __u64 sample_regs_intr;     /* regs to dump on samples */
+    __u32 aux_watermark;        /* aux bytes before wakeup */
+    __u16 sample_max_stack;     /* max frames in callchain */
+    __u16 __reserved_2;         /* align to u64 */
+    __u32 aux_sample_size;      /* max aux sample size */
+    __u32 __reserved_3;         /* align to u64 */
+    __u64 sig_data;             /* user data for sigtrap */
+\&
+};
+.EE
+.in
+.P
+The fields of the
+.I perf_event_attr
+structure are described in more detail below:
+.TP
+.I type
+This field specifies the overall event type.
+It has one of the following values:
+.RS
+.TP
+.B PERF_TYPE_HARDWARE
+This indicates one of the "generalized" hardware events provided
+by the kernel.
+See the
+.I config
+field definition for more details.
+.TP
+.B PERF_TYPE_SOFTWARE
+This indicates one of the software-defined events provided by the kernel
+(even if no hardware support is available).
+.TP
+.B PERF_TYPE_TRACEPOINT
+This indicates a tracepoint
+provided by the kernel tracepoint infrastructure.
+.TP
+.B PERF_TYPE_HW_CACHE
+This indicates a hardware cache event.
+This has a special encoding, described in the
+.I config
+field definition.
+.TP
+.B PERF_TYPE_RAW
+This indicates a "raw" implementation-specific event in the
+.IR config " field."
+.TP
+.BR PERF_TYPE_BREAKPOINT " (since Linux 2.6.33)"
+.\" commit 24f1e32c60c45c89a997c73395b69c8af6f0a84e
+This indicates a hardware breakpoint as provided by the CPU.
+Breakpoints can be read/write accesses to an address as well as
+execution of an instruction address.
+.TP
+dynamic PMU
+Since Linux 2.6.38,
+.\" commit 2e80a82a49c4c7eca4e35734380f28298ba5db19
+.BR perf_event_open ()
+can support multiple PMUs.
+To enable this, a value exported by the kernel can be used in the
+.I type
+field to indicate which PMU to use.
+The value to use can be found in the sysfs filesystem:
+there is a subdirectory per PMU instance under
+.IR /sys/bus/event_source/devices .
+In each subdirectory there is a
+.I type
+file whose content is an integer that can be used in the
+.I type
+field.
+For instance,
+.I /sys/bus/event_source/devices/cpu/type
+contains the value for the core CPU PMU, which is usually 4.
+.TP
+.BR kprobe " and " uprobe " (since Linux 4.17)"
+.\" commit 65074d43fc77bcae32776724b7fa2696923c78e4
+.\" commit e12f03d7031a977356e3d7b75a68c2185ff8d155
+.\" commit 33ea4b24277b06dbc55d7f5772a46f029600255e
+These two dynamic PMUs create a kprobe/uprobe and attach it to the
+file descriptor generated by perf_event_open.
+The kprobe/uprobe will be destroyed on the destruction of the file descriptor.
+See fields
+.IR kprobe_func ,
+.IR uprobe_path ,
+.IR kprobe_addr ,
+and
+.I probe_offset
+for more details.
+.RE
+.TP
+.I "size"
+The size of the
+.I perf_event_attr
+structure for forward/backward compatibility.
+Set this using
+.I sizeof(struct perf_event_attr)
+to allow the kernel to see
+the struct size at the time of compilation.
+.IP
+The related define
+.B PERF_ATTR_SIZE_VER0
+is set to 64; this was the size of the first published struct.
+.B PERF_ATTR_SIZE_VER1
+is 72, corresponding to the addition of breakpoints in Linux 2.6.33.
+.\" commit cb5d76999029ae7a517cb07dfa732c1b5a934fc2
+.\" this was added much later when PERF_ATTR_SIZE_VER2 happened
+.\" but the actual attr_size had increased in Linux 2.6.33
+.B PERF_ATTR_SIZE_VER2
+is 80 corresponding to the addition of branch sampling in Linux 3.4.
+.\" commit cb5d76999029ae7a517cb07dfa732c1b5a934fc2
+.B PERF_ATTR_SIZE_VER3
+is 96 corresponding to the addition
+of
+.I sample_regs_user
+and
+.I sample_stack_user
+in Linux 3.7.
+.\" commit 1659d129ed014b715b0b2120e6fd929bdd33ed03
+.B PERF_ATTR_SIZE_VER4
+is 104 corresponding to the addition of
+.I sample_regs_intr
+in Linux 3.19.
+.\" commit 60e2364e60e86e81bc6377f49779779e6120977f
+.B PERF_ATTR_SIZE_VER5
+is 112 corresponding to the addition of
+.I aux_watermark
+in Linux 4.1.
+.\" commit 1a5941312414c71dece6717da9a0fa1303127afa
+.TP
+.I "config"
+This specifies which event you want, in conjunction with
+the
+.I type
+field.
+The
+.I config1
+and
+.I config2
+fields are also taken into account in cases where 64 bits is not
+enough to fully specify the event.
+The encoding of these fields are event dependent.
+.IP
+There are various ways to set the
+.I config
+field that are dependent on the value of the previously
+described
+.I type
+field.
+What follows are various possible settings for
+.I config
+separated out by
+.IR type .
+.IP
+If
+.I type
+is
+.BR PERF_TYPE_HARDWARE ,
+we are measuring one of the generalized hardware CPU events.
+Not all of these are available on all platforms.
+Set
+.I config
+to one of the following:
+.RS 12
+.TP
+.B PERF_COUNT_HW_CPU_CYCLES
+Total cycles.
+Be wary of what happens during CPU frequency scaling.
+.TP
+.B PERF_COUNT_HW_INSTRUCTIONS
+Retired instructions.
+Be careful, these can be affected by various
+issues, most notably hardware interrupt counts.
+.TP
+.B PERF_COUNT_HW_CACHE_REFERENCES
+Cache accesses.
+Usually this indicates Last Level Cache accesses but this may
+vary depending on your CPU.
+This may include prefetches and coherency messages; again this
+depends on the design of your CPU.
+.TP
+.B PERF_COUNT_HW_CACHE_MISSES
+Cache misses.
+Usually this indicates Last Level Cache misses; this is intended to be
+used in conjunction with the
+.B PERF_COUNT_HW_CACHE_REFERENCES
+event to calculate cache miss rates.
+.TP
+.B PERF_COUNT_HW_BRANCH_INSTRUCTIONS
+Retired branch instructions.
+Prior to Linux 2.6.35, this used
+the wrong event on AMD processors.
+.\" commit f287d332ce835f77a4f5077d2c0ef1e3f9ea42d2
+.TP
+.B PERF_COUNT_HW_BRANCH_MISSES
+Mispredicted branch instructions.
+.TP
+.B PERF_COUNT_HW_BUS_CYCLES
+Bus cycles, which can be different from total cycles.
+.TP
+.BR PERF_COUNT_HW_STALLED_CYCLES_FRONTEND " (since Linux 3.0)"
+.\" commit 8f62242246351b5a4bc0c1f00c0c7003edea128a
+Stalled cycles during issue.
+.TP
+.BR PERF_COUNT_HW_STALLED_CYCLES_BACKEND  " (since Linux 3.0)"
+.\" commit 8f62242246351b5a4bc0c1f00c0c7003edea128a
+Stalled cycles during retirement.
+.TP
+.BR PERF_COUNT_HW_REF_CPU_CYCLES  " (since Linux 3.3)"
+.\" commit c37e17497e01fc0f5d2d6feb5723b210b3ab8890
+Total cycles; not affected by CPU frequency scaling.
+.RE
+.IP
+If
+.I type
+is
+.BR PERF_TYPE_SOFTWARE ,
+we are measuring software events provided by the kernel.
+Set
+.I config
+to one of the following:
+.RS 12
+.TP
+.B PERF_COUNT_SW_CPU_CLOCK
+This reports the CPU clock, a high-resolution per-CPU timer.
+.TP
+.B PERF_COUNT_SW_TASK_CLOCK
+This reports a clock count specific to the task that is running.
+.TP
+.B PERF_COUNT_SW_PAGE_FAULTS
+This reports the number of page faults.
+.TP
+.B PERF_COUNT_SW_CONTEXT_SWITCHES
+This counts context switches.
+Until Linux 2.6.34, these were all reported as user-space
+events, after that they are reported as happening in the kernel.
+.\" commit e49a5bd38159dfb1928fd25b173bc9de4bbadb21
+.TP
+.B PERF_COUNT_SW_CPU_MIGRATIONS
+This reports the number of times the process
+has migrated to a new CPU.
+.TP
+.B PERF_COUNT_SW_PAGE_FAULTS_MIN
+This counts the number of minor page faults.
+These did not require disk I/O to handle.
+.TP
+.B PERF_COUNT_SW_PAGE_FAULTS_MAJ
+This counts the number of major page faults.
+These required disk I/O to handle.
+.TP
+.BR PERF_COUNT_SW_ALIGNMENT_FAULTS " (since Linux 2.6.33)"
+.\" commit f7d7986060b2890fc26db6ab5203efbd33aa2497
+This counts the number of alignment faults.
+These happen when unaligned memory accesses happen; the kernel
+can handle these but it reduces performance.
+This happens only on some architectures (never on x86).
+.TP
+.BR PERF_COUNT_SW_EMULATION_FAULTS " (since Linux 2.6.33)"
+.\" commit f7d7986060b2890fc26db6ab5203efbd33aa2497
+This counts the number of emulation faults.
+The kernel sometimes traps on unimplemented instructions
+and emulates them for user space.
+This can negatively impact performance.
+.TP
+.BR PERF_COUNT_SW_DUMMY " (since Linux 3.12)"
+.\" commit fa0097ee690693006ab1aea6c01ad3c851b65c77
+This is a placeholder event that counts nothing.
+Informational sample record types such as mmap or comm
+must be associated with an active event.
+This dummy event allows gathering such records without requiring
+a counting event.
+.TP
+.BR PERF_COUNT_SW_BPF_OUTPUT " (since Linux 4.4)"
+.\" commit a43eec304259a6c637f4014a6d4767159b6a3aa3
+This is used to generate raw sample data from BPF.
+BPF programs can write to this event using
+.B bpf_perf_event_output
+helper.
+.TP
+.BR PERF_COUNT_SW_CGROUP_SWITCHES " (since Linux 5.13)"
+.\" commit d0d1dd628527c77db2391ce0293c1ed344b2365f
+This counts context switches to a task in a different cgroup.
+In other words, if the next task is in the same cgroup,
+it won't count the switch.
+.RE
+.P
+.RS
+If
+.I type
+is
+.BR PERF_TYPE_TRACEPOINT ,
+then we are measuring kernel tracepoints.
+The value to use in
+.I config
+can be obtained from under debugfs
+.I tracing/events/*/*/id
+if ftrace is enabled in the kernel.
+.RE
+.P
+.RS
+If
+.I type
+is
+.BR PERF_TYPE_HW_CACHE ,
+then we are measuring a hardware CPU cache event.
+To calculate the appropriate
+.I config
+value, use the following equation:
+.RS 4
+.P
+.in +4n
+.EX
+config = (perf_hw_cache_id) |
+         (perf_hw_cache_op_id << 8) |
+         (perf_hw_cache_op_result_id << 16);
+.EE
+.in
+.P
+where
+.I perf_hw_cache_id
+is one of:
+.RS 4
+.TP
+.B PERF_COUNT_HW_CACHE_L1D
+for measuring Level 1 Data Cache
+.TP
+.B PERF_COUNT_HW_CACHE_L1I
+for measuring Level 1 Instruction Cache
+.TP
+.B PERF_COUNT_HW_CACHE_LL
+for measuring Last-Level Cache
+.TP
+.B PERF_COUNT_HW_CACHE_DTLB
+for measuring the Data TLB
+.TP
+.B PERF_COUNT_HW_CACHE_ITLB
+for measuring the Instruction TLB
+.TP
+.B PERF_COUNT_HW_CACHE_BPU
+for measuring the branch prediction unit
+.TP
+.BR PERF_COUNT_HW_CACHE_NODE " (since Linux 3.1)"
+.\" commit 89d6c0b5bdbb1927775584dcf532d98b3efe1477
+for measuring local memory accesses
+.RE
+.P
+and
+.I perf_hw_cache_op_id
+is one of:
+.RS 4
+.TP
+.B PERF_COUNT_HW_CACHE_OP_READ
+for read accesses
+.TP
+.B PERF_COUNT_HW_CACHE_OP_WRITE
+for write accesses
+.TP
+.B PERF_COUNT_HW_CACHE_OP_PREFETCH
+for prefetch accesses
+.RE
+.P
+and
+.I perf_hw_cache_op_result_id
+is one of:
+.RS 4
+.TP
+.B PERF_COUNT_HW_CACHE_RESULT_ACCESS
+to measure accesses
+.TP
+.B PERF_COUNT_HW_CACHE_RESULT_MISS
+to measure misses
+.RE
+.RE
+.P
+If
+.I type
+is
+.BR PERF_TYPE_RAW ,
+then a custom "raw"
+.I config
+value is needed.
+Most CPUs support events that are not covered by the "generalized" events.
+These are implementation defined; see your CPU manual (for example
+the Intel Volume 3B documentation or the AMD BIOS and Kernel Developer
+Guide).
+The libpfm4 library can be used to translate from the name in the
+architectural manuals to the raw hex value
+.BR perf_event_open ()
+expects in this field.
+.P
+If
+.I type
+is
+.BR PERF_TYPE_BREAKPOINT ,
+then leave
+.I config
+set to zero.
+Its parameters are set in other places.
+.P
+If
+.I type
+is
+.B kprobe
+or
+.BR uprobe ,
+set
+.I retprobe
+(bit 0 of
+.IR config ,
+see
+.IR /sys/bus/event_source/devices/[k,u]probe/format/retprobe )
+for kretprobe/uretprobe.
+See fields
+.IR kprobe_func ,
+.IR uprobe_path ,
+.IR kprobe_addr ,
+and
+.I probe_offset
+for more details.
+.RE
+.TP
+.I kprobe_func
+.TQ
+.I uprobe_path
+.TQ
+.I kprobe_addr
+.TQ
+.I probe_offset
+These fields describe the kprobe/uprobe for dynamic PMUs
+.B kprobe
+and
+.BR uprobe .
+For
+.BR kprobe :
+use
+.I kprobe_func
+and
+.IR probe_offset ,
+or use
+.I kprobe_addr
+and leave
+.I kprobe_func
+as NULL.
+For
+.BR uprobe :
+use
+.I uprobe_path
+and
+.IR probe_offset .
+.TP
+.I sample_period
+.TQ
+.I sample_freq
+A "sampling" event is one that generates an overflow notification
+every N events, where N is given by
+.IR sample_period .
+A sampling event has
+.IR sample_period " > 0."
+When an overflow occurs, requested data is recorded
+in the mmap buffer.
+The
+.I sample_type
+field controls what data is recorded on each overflow.
+.IP
+.I sample_freq
+can be used if you wish to use frequency rather than period.
+In this case, you set the
+.I freq
+flag.
+The kernel will adjust the sampling period
+to try and achieve the desired rate.
+The rate of adjustment is a
+timer tick.
+.TP
+.I sample_type
+The various bits in this field specify which values to include
+in the sample.
+They will be recorded in a ring-buffer,
+which is available to user space using
+.BR mmap (2).
+The order in which the values are saved in the
+sample are documented in the MMAP Layout subsection below;
+it is not the
+.I "enum perf_event_sample_format"
+order.
+.RS
+.TP
+.B PERF_SAMPLE_IP
+Records instruction pointer.
+.TP
+.B PERF_SAMPLE_TID
+Records the process and thread IDs.
+.TP
+.B PERF_SAMPLE_TIME
+Records a timestamp.
+.TP
+.B PERF_SAMPLE_ADDR
+Records an address, if applicable.
+.TP
+.B PERF_SAMPLE_READ
+Record counter values for all events in a group, not just the group leader.
+.TP
+.B PERF_SAMPLE_CALLCHAIN
+Records the callchain (stack backtrace).
+.TP
+.B PERF_SAMPLE_ID
+Records a unique ID for the opened event's group leader.
+.TP
+.B PERF_SAMPLE_CPU
+Records CPU number.
+.TP
+.B PERF_SAMPLE_PERIOD
+Records the current sampling period.
+.TP
+.B PERF_SAMPLE_STREAM_ID
+Records a unique ID for the opened event.
+Unlike
+.B PERF_SAMPLE_ID
+the actual ID is returned, not the group leader.
+This ID is the same as the one returned by
+.BR PERF_FORMAT_ID .
+.TP
+.B PERF_SAMPLE_RAW
+Records additional data, if applicable.
+Usually returned by tracepoint events.
+.TP
+.BR PERF_SAMPLE_BRANCH_STACK " (since Linux 3.4)"
+.\" commit bce38cd53e5ddba9cb6d708c4ef3d04a4016ec7e
+This provides a record of recent branches, as provided
+by CPU branch sampling hardware (such as Intel Last Branch Record).
+Not all hardware supports this feature.
+.IP
+See the
+.I branch_sample_type
+field for how to filter which branches are reported.
+.TP
+.BR PERF_SAMPLE_REGS_USER " (since Linux 3.7)"
+.\" commit 4018994f3d8785275ef0e7391b75c3462c029e56
+Records the current user-level CPU register state
+(the values in the process before the kernel was called).
+.TP
+.BR PERF_SAMPLE_STACK_USER " (since Linux 3.7)"
+.\" commit c5ebcedb566ef17bda7b02686e0d658a7bb42ee7
+Records the user level stack, allowing stack unwinding.
+.TP
+.BR PERF_SAMPLE_WEIGHT " (since Linux 3.10)"
+.\" commit c3feedf2aaf9ac8bad6f19f5d21e4ee0b4b87e9c
+Records a hardware provided weight value that expresses how
+costly the sampled event was.
+This allows the hardware to highlight expensive events in
+a profile.
+.TP
+.BR PERF_SAMPLE_DATA_SRC " (since Linux 3.10)"
+.\" commit d6be9ad6c960f43800a6f118932bc8a5a4eadcd1
+Records the data source: where in the memory hierarchy
+the data associated with the sampled instruction came from.
+This is available only if the underlying hardware
+supports this feature.
+.TP
+.BR PERF_SAMPLE_IDENTIFIER " (since Linux 3.12)"
+.\" commit ff3d527cebc1fa3707c617bfe9e74f53fcfb0955
+Places the
+.B SAMPLE_ID
+value in a fixed position in the record,
+either at the beginning (for sample events) or at the end
+(if a non-sample event).
+.IP
+This was necessary because a sample stream may have
+records from various different event sources with different
+.I sample_type
+settings.
+Parsing the event stream properly was not possible because the
+format of the record was needed to find
+.BR SAMPLE_ID ,
+but
+the format could not be found without knowing what
+event the sample belonged to (causing a circular
+dependency).
+.IP
+The
+.B PERF_SAMPLE_IDENTIFIER
+setting makes the event stream always parsable
+by putting
+.B SAMPLE_ID
+in a fixed location, even though
+it means having duplicate
+.B SAMPLE_ID
+values in records.
+.TP
+.BR PERF_SAMPLE_TRANSACTION " (since Linux 3.13)"
+.\" commit fdfbbd07e91f8fe387140776f3fd94605f0c89e5
+Records reasons for transactional memory abort events
+(for example, from Intel TSX transactional memory support).
+.IP
+The
+.I precise_ip
+setting must be greater than 0 and a transactional memory abort
+event must be measured or no values will be recorded.
+Also note that some perf_event measurements, such as sampled
+cycle counting, may cause extraneous aborts (by causing an
+interrupt during a transaction).
+.TP
+.BR PERF_SAMPLE_REGS_INTR " (since Linux 3.19)"
+.\" commit 60e2364e60e86e81bc6377f49779779e6120977f
+Records a subset of the current CPU register state
+as specified by
+.IR sample_regs_intr .
+Unlike
+.B PERF_SAMPLE_REGS_USER
+the register values will return kernel register
+state if the overflow happened while kernel
+code is running.
+If the CPU supports hardware sampling of
+register state (i.e., PEBS on Intel x86) and
+.I precise_ip
+is set higher than zero then the register
+values returned are those captured by
+hardware at the time of the sampled
+instruction's retirement.
+.TP
+.BR PERF_SAMPLE_PHYS_ADDR " (since Linux 4.13)"
+.\" commit fc7ce9c74c3ad232b084d80148654f926d01ece7
+Records physical address of data like in
+.BR PERF_SAMPLE_ADDR .
+.TP
+.BR PERF_SAMPLE_CGROUP " (since Linux 5.7)"
+.\" commit 96aaab686505c449e24d76e76507290dcc30e008
+Records (perf_event) cgroup ID of the process.
+This corresponds to the
+.I id
+field in the
+.B PERF_RECORD_CGROUP
+event.
+.TP
+.BR PERF_SAMPLE_DATA_PAGE_SIZE " (since Linux 5.11)"
+.\" commit 8d97e71811aaafe4abf611dc24822fd6e73df1a1
+Records page size of data like in
+.BR PERF_SAMPLE_ADDR .
+.TP
+.BR PERF_SAMPLE_CODE_PAGE_SIZE " (since Linux 5.11)"
+.\" commit 995f088efebe1eba0282a6ffa12411b37f8990c2
+Records page size of ip like in
+.BR PERF_SAMPLE_IP .
+.TP
+.BR PERF_SAMPLE_WEIGHT_STRUCT " (since Linux 5.12)"
+.\" commit 2a6c6b7d7ad346f0679d0963cb19b3f0ea7ef32c
+Records hardware provided weight values like in
+.BR PERF_SAMPLE_WEIGHT ,
+but it can represent multiple values in a struct.
+This shares the same space as
+.BR PERF_SAMPLE_WEIGHT ,
+so users can apply either of those,
+not both.
+It has the following format and
+the meaning of each field is
+dependent on the hardware implementation.
+.P
+.in +4n
+.EX
+union perf_sample_weight {
+    u64  full;           /* PERF_SAMPLE_WEIGHT */
+    struct {             /* PERF_SAMPLE_WEIGHT_STRUCT */
+        u32  var1_dw;
+        u16  var2_w;
+        u16  var3_w;
+    };
+};
+.EE
+.in
+.RE
+.TP
+.I read_format
+This field specifies the format of the data returned by
+.BR read (2)
+on a
+.BR perf_event_open ()
+file descriptor.
+.RS
+.TP
+.B PERF_FORMAT_TOTAL_TIME_ENABLED
+Adds the 64-bit
+.I time_enabled
+field.
+This can be used to calculate estimated totals if
+the PMU is overcommitted and multiplexing is happening.
+.TP
+.B PERF_FORMAT_TOTAL_TIME_RUNNING
+Adds the 64-bit
+.I time_running
+field.
+This can be used to calculate estimated totals if
+the PMU is overcommitted and multiplexing is happening.
+.TP
+.B PERF_FORMAT_ID
+Adds a 64-bit unique value that corresponds to the event group.
+.TP
+.B PERF_FORMAT_GROUP
+Allows all counter values in an event group to be read with one read.
+.TP
+.B PERF_FORMAT_LOST " (since Linux 6.0)"
+.\" commit 119a784c81270eb88e573174ed2209225d646656
+Adds a 64-bit value that is the number of lost samples for this event.
+This would be only meaningful when
+.I sample_period
+or
+.I sample_freq
+is set.
+.RE
+.TP
+.I disabled
+The
+.I disabled
+bit specifies whether the counter starts out disabled or enabled.
+If disabled, the event can later be enabled by
+.BR ioctl (2),
+.BR prctl (2),
+or
+.IR enable_on_exec .
+.IP
+When creating an event group, typically the group leader is initialized
+with
+.I disabled
+set to 1 and any child events are initialized with
+.I disabled
+set to 0.
+Despite
+.I disabled
+being 0, the child events will not start until the group leader
+is enabled.
+.TP
+.I inherit
+The
+.I inherit
+bit specifies that this counter should count events of child
+tasks as well as the task specified.
+This applies only to new children, not to any existing children at
+the time the counter is created (nor to any new children of
+existing children).
+.IP
+Inherit does not work for some combinations of
+.I read_format
+values, such as
+.BR PERF_FORMAT_GROUP .
+.TP
+.I pinned
+The
+.I pinned
+bit specifies that the counter should always be on the CPU if at all
+possible.
+It applies only to hardware counters and only to group leaders.
+If a pinned counter cannot be put onto the CPU (e.g., because there are
+not enough hardware counters or because of a conflict with some other
+event), then the counter goes into an 'error' state, where reads
+return end-of-file (i.e.,
+.BR read (2)
+returns 0) until the counter is subsequently enabled or disabled.
+.TP
+.I exclusive
+The
+.I exclusive
+bit specifies that when this counter's group is on the CPU,
+it should be the only group using the CPU's counters.
+In the future this may allow monitoring programs to
+support PMU features that need to run alone so that they do not
+disrupt other hardware counters.
+.IP
+Note that many unexpected situations may prevent events with the
+.I exclusive
+bit set from ever running.
+This includes any users running a system-wide
+measurement as well as any kernel use of the performance counters
+(including the commonly enabled NMI Watchdog Timer interface).
+.TP
+.I exclude_user
+If this bit is set, the count excludes events that happen in user space.
+.TP
+.I exclude_kernel
+If this bit is set, the count excludes events that happen in kernel space.
+.TP
+.I exclude_hv
+If this bit is set, the count excludes events that happen in the
+hypervisor.
+This is mainly for PMUs that have built-in support for handling this
+(such as POWER).
+Extra support is needed for handling hypervisor measurements on most
+machines.
+.TP
+.I exclude_idle
+If set, don't count when the CPU is running the idle task.
+While you can currently enable this for any event type, it is ignored
+for all but software events.
+.TP
+.I mmap
+The
+.I mmap
+bit enables generation of
+.B PERF_RECORD_MMAP
+samples for every
+.BR mmap (2)
+call that has
+.B PROT_EXEC
+set.
+This allows tools to notice new executable code being mapped into
+a program (dynamic shared libraries for example)
+so that addresses can be mapped back to the original code.
+.TP
+.I comm
+The
+.I comm
+bit enables tracking of process command name as modified by the
+.BR execve (2)
+and
+.BR prctl (PR_SET_NAME)
+system calls as well as writing to
+.IR /proc/self/comm .
+If the
+.I comm_exec
+flag is also successfully set (possible since Linux 3.16),
+.\" commit 82b897782d10fcc4930c9d4a15b175348fdd2871
+then the misc flag
+.B PERF_RECORD_MISC_COMM_EXEC
+can be used to differentiate the
+.BR execve (2)
+case from the others.
+.TP
+.I freq
+If this bit is set, then
+.I sample_frequency
+not
+.I sample_period
+is used when setting up the sampling interval.
+.TP
+.I inherit_stat
+This bit enables saving of event counts on context switch for
+inherited tasks.
+This is meaningful only if the
+.I inherit
+field is set.
+.TP
+.I enable_on_exec
+If this bit is set, a counter is automatically
+enabled after a call to
+.BR execve (2).
+.TP
+.I task
+If this bit is set, then
+fork/exit notifications are included in the ring buffer.
+.TP
+.I watermark
+If set, have an overflow notification happen when we cross the
+.I wakeup_watermark
+boundary.
+Otherwise, overflow notifications happen after
+.I wakeup_events
+samples.
+.TP
+.IR precise_ip " (since Linux 2.6.35)"
+.\" commit ab608344bcbde4f55ec4cd911b686b0ce3eae076
+This controls the amount of skid.
+Skid is how many instructions
+execute between an event of interest happening and the kernel
+being able to stop and record the event.
+Smaller skid is
+better and allows more accurate reporting of which events
+correspond to which instructions, but hardware is often limited
+with how small this can be.
+.IP
+The possible values of this field are the following:
+.RS
+.TP
+.B 0
+.B SAMPLE_IP
+can have arbitrary skid.
+.TP
+.B 1
+.B SAMPLE_IP
+must have constant skid.
+.TP
+.B 2
+.B SAMPLE_IP
+requested to have 0 skid.
+.TP
+.B 3
+.B SAMPLE_IP
+must have 0 skid.
+See also the description of
+.BR PERF_RECORD_MISC_EXACT_IP .
+.RE
+.TP
+.IR mmap_data " (since Linux 2.6.36)"
+.\" commit 3af9e859281bda7eb7c20b51879cf43aa788ac2e
+This is the counterpart of the
+.I mmap
+field.
+This enables generation of
+.B PERF_RECORD_MMAP
+samples for
+.BR mmap (2)
+calls that do not have
+.B PROT_EXEC
+set (for example data and SysV shared memory).
+.TP
+.IR sample_id_all " (since Linux 2.6.38)"
+.\" commit c980d1091810df13f21aabbce545fd98f545bbf7
+If set, then TID, TIME, ID, STREAM_ID, and CPU can
+additionally be included in
+.RB non- PERF_RECORD_SAMPLE s
+if the corresponding
+.I sample_type
+is selected.
+.IP
+If
+.B PERF_SAMPLE_IDENTIFIER
+is specified, then an additional ID value is included
+as the last value to ease parsing the record stream.
+This may lead to the
+.I id
+value appearing twice.
+.IP
+The layout is described by this pseudo-structure:
+.IP
+.in +4n
+.EX
+struct sample_id {
+    { u32 pid, tid; }   /* if PERF_SAMPLE_TID set */
+    { u64 time;     }   /* if PERF_SAMPLE_TIME set */
+    { u64 id;       }   /* if PERF_SAMPLE_ID set */
+    { u64 stream_id;}   /* if PERF_SAMPLE_STREAM_ID set  */
+    { u32 cpu, res; }   /* if PERF_SAMPLE_CPU set */
+    { u64 id;       }   /* if PERF_SAMPLE_IDENTIFIER set */
+};
+.EE
+.in
+.TP
+.IR exclude_host " (since Linux 3.2)"
+.\" commit a240f76165e6255384d4bdb8139895fac7988799
+When conducting measurements that include processes running
+VM instances (i.e., have executed a
+.B KVM_RUN
+.BR ioctl (2)),
+only measure events happening inside a guest instance.
+This is only meaningful outside the guests; this setting does
+not change counts gathered inside of a guest.
+Currently, this functionality is x86 only.
+.TP
+.IR exclude_guest " (since Linux 3.2)"
+.\" commit a240f76165e6255384d4bdb8139895fac7988799
+When conducting measurements that include processes running
+VM instances (i.e., have executed a
+.B KVM_RUN
+.BR ioctl (2)),
+do not measure events happening inside guest instances.
+This is only meaningful outside the guests; this setting does
+not change counts gathered inside of a guest.
+Currently, this functionality is x86 only.
+.TP
+.IR exclude_callchain_kernel " (since Linux 3.7)"
+.\" commit d077526485d5c9b12fe85d0b2b3b7041e6bc5f91
+Do not include kernel callchains.
+.TP
+.IR exclude_callchain_user " (since Linux 3.7)"
+.\" commit d077526485d5c9b12fe85d0b2b3b7041e6bc5f91
+Do not include user callchains.
+.TP
+.IR mmap2 " (since Linux 3.16)"
+.\" commit 13d7a2410fa637f450a29ecb515ac318ee40c741
+.\" This is tricky; was committed during 3.12 development
+.\" but right before release was disabled.
+.\" So while you could select mmap2 starting with Linux 3.12
+.\" it did not work until Linux 3.16
+.\" commit a5a5ba72843dd05f991184d6cb9a4471acce1005
+Generate an extended executable mmap record that contains enough
+additional information to uniquely identify shared mappings.
+The
+.I mmap
+flag must also be set for this to work.
+.TP
+.IR comm_exec " (since Linux 3.16)"
+.\" commit 82b897782d10fcc4930c9d4a15b175348fdd2871
+This is purely a feature-detection flag, it does not change
+kernel behavior.
+If this flag can successfully be set, then, when
+.I comm
+is enabled, the
+.B PERF_RECORD_MISC_COMM_EXEC
+flag will be set in the
+.I misc
+field of a comm record header if the rename event being
+reported was caused by a call to
+.BR execve (2).
+This allows tools to distinguish between the various
+types of process renaming.
+.TP
+.IR use_clockid " (since Linux 4.1)"
+.\" commit 34f439278cef7b1177f8ce24f9fc81dfc6221d3b
+This allows selecting which internal Linux clock to use
+when generating timestamps via the
+.I clockid
+field.
+This can make it easier to correlate perf sample times with
+timestamps generated by other tools.
+.TP
+.IR context_switch " (since Linux 4.3)"
+.\" commit 45ac1403f564f411c6a383a2448688ba8dd705a4
+This enables the generation of
+.B PERF_RECORD_SWITCH
+records when a context switch occurs.
+It also enables the generation of
+.B PERF_RECORD_SWITCH_CPU_WIDE
+records when sampling in CPU-wide mode.
+This functionality is in addition to existing tracepoint and
+software events for measuring context switches.
+The advantage of this method is that it will give full
+information even with strict
+.I perf_event_paranoid
+settings.
+.TP
+.IR write_backward " (since Linux 4.6)"
+.\" commit 9ecda41acb971ebd07c8fb35faf24005c0baea12
+This causes the ring buffer to be written from the end to the beginning.
+This is to support reading from overwritable ring buffer.
+.TP
+.IR namespaces " (since Linux 4.11)"
+.\" commit e422267322cd319e2695a535e47c5b1feeac45eb
+This enables the generation of
+.B PERF_RECORD_NAMESPACES
+records when a task enters a new namespace.
+Each namespace has a combination of device and inode numbers.
+.TP
+.IR ksymbol " (since Linux 5.0)"
+.\" commit 76193a94522f1d4edf2447a536f3f796ce56343b
+This enables the generation of
+.B PERF_RECORD_KSYMBOL
+records when new kernel symbols are registered or unregistered.
+This is analyzing dynamic kernel functions like eBPF.
+.TP
+.IR bpf_event " (since Linux 5.0)"
+.\" commit 6ee52e2a3fe4ea35520720736e6791df1fb67106
+This enables the generation of
+.B PERF_RECORD_BPF_EVENT
+records when an eBPF program is loaded or unloaded.
+.TP
+.IR aux_output " (since Linux 5.4)"
+.\" commit ab43762ef010967e4ccd53627f70a2eecbeafefb
+This allows normal (non-AUX) events to generate data for AUX events
+if the hardware supports it.
+.TP
+.IR cgroup " (since Linux 5.7)"
+.\" commit 96aaab686505c449e24d76e76507290dcc30e008
+This enables the generation of
+.B PERF_RECORD_CGROUP
+records when a new cgroup is created (and activated).
+.TP
+.IR text_poke " (since Linux 5.8)"
+.\" commit e17d43b93e544f5016c0251d2074c15568d5d963
+This enables the generation of
+.B PERF_RECORD_TEXT_POKE
+records when there's a change to the kernel text
+(i.e., self-modifying code).
+.TP
+.IR build_id " (since Linux 5.12)"
+.\" commit 88a16a1309333e43d328621ece3e9fa37027e8eb
+This changes the contents in the
+.B PERF_RECORD_MMAP2
+to have a build-id instead of device and inode numbers.
+.TP
+.IR inherit_thread " (since Linux 5.13)"
+.\" commit 2b26f0aa004995f49f7b6f4100dd0e4c39a9ed5f
+This disables the inheritance of the event to a child process.
+Only new threads in the same process
+(which is cloned with
+.BR CLONE_THREAD )
+will inherit the event.
+.TP
+.IR remove_on_exec " (since Linux 5.13)"
+.\" commit 2e498d0a74e5b88a6689ae1b811f247f91ff188e
+This closes the event when it starts a new process image by
+.BR execve (2).
+.TP
+.IR sigtrap " (since Linux 5.13)"
+.\" commit 97ba62b278674293762c3d91f724f1bb922f04e0
+This enables synchronous signal delivery of
+.B SIGTRAP
+on event overflow.
+.TP
+.I wakeup_events
+.TQ
+.I wakeup_watermark
+This union sets how many samples
+.RI ( wakeup_events )
+or bytes
+.RI ( wakeup_watermark )
+happen before an overflow notification happens.
+Which one is used is selected by the
+.I watermark
+bit flag.
+.IP
+.I wakeup_events
+counts only
+.B PERF_RECORD_SAMPLE
+record types.
+To receive overflow notification for all
+.B PERF_RECORD
+types choose watermark and set
+.I wakeup_watermark
+to 1.
+.IP
+Prior to Linux 3.0, setting
+.\" commit f506b3dc0ec454a16d40cab9ee5d75435b39dc50
+.I wakeup_events
+to 0 resulted in no overflow notifications;
+more recent kernels treat 0 the same as 1.
+.TP
+.IR bp_type " (since Linux 2.6.33)"
+.\" commit 24f1e32c60c45c89a997c73395b69c8af6f0a84e
+This chooses the breakpoint type.
+It is one of:
+.RS
+.TP
+.B HW_BREAKPOINT_EMPTY
+No breakpoint.
+.TP
+.B HW_BREAKPOINT_R
+Count when we read the memory location.
+.TP
+.B HW_BREAKPOINT_W
+Count when we write the memory location.
+.TP
+.B HW_BREAKPOINT_RW
+Count when we read or write the memory location.
+.TP
+.B HW_BREAKPOINT_X
+Count when we execute code at the memory location.
+.P
+The values can be combined via a bitwise or, but the
+combination of
+.B HW_BREAKPOINT_R
+or
+.B HW_BREAKPOINT_W
+with
+.B HW_BREAKPOINT_X
+is not allowed.
+.RE
+.TP
+.IR bp_addr " (since Linux 2.6.33)"
+.\" commit 24f1e32c60c45c89a997c73395b69c8af6f0a84e
+This is the address of the breakpoint.
+For execution breakpoints, this is the memory address of the instruction
+of interest; for read and write breakpoints, it is the memory address
+of the memory location of interest.
+.TP
+.IR config1 " (since Linux 2.6.39)"
+.\" commit a7e3ed1e470116c9d12c2f778431a481a6be8ab6
+.I config1
+is used for setting events that need an extra register or otherwise
+do not fit in the regular config field.
+Raw OFFCORE_EVENTS on Nehalem/Westmere/SandyBridge use this field
+on Linux 3.3 and later kernels.
+.TP
+.IR bp_len " (since Linux 2.6.33)"
+.\" commit 24f1e32c60c45c89a997c73395b69c8af6f0a84e
+.I bp_len
+is the length of the breakpoint being measured if
+.I type
+is
+.BR PERF_TYPE_BREAKPOINT .
+Options are
+.BR HW_BREAKPOINT_LEN_1 ,
+.BR HW_BREAKPOINT_LEN_2 ,
+.BR HW_BREAKPOINT_LEN_4 ,
+and
+.BR HW_BREAKPOINT_LEN_8 .
+For an execution breakpoint, set this to
+.IR sizeof(long) .
+.TP
+.IR config2 " (since Linux 2.6.39)"
+.\" commit a7e3ed1e470116c9d12c2f778431a481a6be8ab6
+.I config2
+is a further extension of the
+.I config1
+field.
+.TP
+.IR branch_sample_type " (since Linux 3.4)"
+.\" commit bce38cd53e5ddba9cb6d708c4ef3d04a4016ec7e
+If
+.B PERF_SAMPLE_BRANCH_STACK
+is enabled, then this specifies what branches to include
+in the branch record.
+.IP
+The first part of the value is the privilege level, which
+is a combination of one of the values listed below.
+If the user does not set privilege level explicitly, the kernel
+will use the event's privilege level.
+Event and branch privilege levels do not have to match.
+.RS
+.TP
+.B PERF_SAMPLE_BRANCH_USER
+Branch target is in user space.
+.TP
+.B PERF_SAMPLE_BRANCH_KERNEL
+Branch target is in kernel space.
+.TP
+.B PERF_SAMPLE_BRANCH_HV
+Branch target is in hypervisor.
+.TP
+.B PERF_SAMPLE_BRANCH_PLM_ALL
+A convenience value that is the three preceding values ORed together.
+.P
+In addition to the privilege value, at least one or more of the
+following bits must be set.
+.TP
+.B PERF_SAMPLE_BRANCH_ANY
+Any branch type.
+.TP
+.B PERF_SAMPLE_BRANCH_ANY_CALL
+Any call branch (includes direct calls, indirect calls, and far jumps).
+.TP
+.B PERF_SAMPLE_BRANCH_IND_CALL
+Indirect calls.
+.TP
+.BR PERF_SAMPLE_BRANCH_CALL " (since Linux 4.4)"
+.\" commit c229bf9dc179d2023e185c0f705bdf68484c1e73
+Direct calls.
+.TP
+.B PERF_SAMPLE_BRANCH_ANY_RETURN
+Any return branch.
+.TP
+.BR PERF_SAMPLE_BRANCH_IND_JUMP " (since Linux 4.2)"
+.\" commit c9fdfa14c3792c0160849c484e83aa57afd80ccc
+Indirect jumps.
+.TP
+.BR PERF_SAMPLE_BRANCH_COND " (since Linux 3.16)"
+.\" commit bac52139f0b7ab31330e98fd87fc5a2664951050
+Conditional branches.
+.TP
+.BR PERF_SAMPLE_BRANCH_ABORT_TX " (since Linux 3.11)"
+.\" commit 135c5612c460f89657c4698fe2ea753f6f667963
+Transactional memory aborts.
+.TP
+.BR PERF_SAMPLE_BRANCH_IN_TX " (since Linux 3.11)"
+.\" commit 135c5612c460f89657c4698fe2ea753f6f667963
+Branch in transactional memory transaction.
+.TP
+.BR PERF_SAMPLE_BRANCH_NO_TX " (since Linux 3.11)"
+.\" commit 135c5612c460f89657c4698fe2ea753f6f667963
+Branch not in transactional memory transaction.
+.BR PERF_SAMPLE_BRANCH_CALL_STACK " (since Linux 4.1)"
+.\" commit 2c44b1936bb3b135a3fac8b3493394d42e51cf70
+Branch is part of a hardware-generated call stack.
+This requires hardware support, currently only found
+on Intel x86 Haswell or newer.
+.RE
+.TP
+.IR sample_regs_user " (since Linux 3.7)"
+.\" commit 4018994f3d8785275ef0e7391b75c3462c029e56
+This bit mask defines the set of user CPU registers to dump on samples.
+The layout of the register mask is architecture-specific and
+is described in the kernel header file
+.IR arch/ARCH/include/uapi/asm/perf_regs.h .
+.TP
+.IR sample_stack_user " (since Linux 3.7)"
+.\" commit c5ebcedb566ef17bda7b02686e0d658a7bb42ee7
+This defines the size of the user stack to dump if
+.B PERF_SAMPLE_STACK_USER
+is specified.
+.TP
+.IR clockid " (since Linux 4.1)"
+.\" commit 34f439278cef7b1177f8ce24f9fc81dfc6221d3b
+If
+.I use_clockid
+is set, then this field selects which internal Linux timer to
+use for timestamps.
+The available timers are defined in
+.IR linux/time.h ,
+with
+.BR CLOCK_MONOTONIC ,
+.BR CLOCK_MONOTONIC_RAW ,
+.BR CLOCK_REALTIME ,
+.BR CLOCK_BOOTTIME ,
+and
+.B CLOCK_TAI
+currently supported.
+.TP
+.IR aux_watermark " (since Linux 4.1)"
+.\" commit 1a5941312414c71dece6717da9a0fa1303127afa
+This specifies how much data is required to trigger a
+.B PERF_RECORD_AUX
+sample.
+.TP
+.IR sample_max_stack " (since Linux 4.8)"
+.\" commit 97c79a38cd454602645f0470ffb444b3b75ce574
+When
+.I sample_type
+includes
+.BR PERF_SAMPLE_CALLCHAIN ,
+this field specifies how many stack frames to report when
+generating the callchain.
+.TP
+.IR aux_sample_size " (since Linux 5.5)"
+.\" commit a4faf00d994c40e64f656805ac375c65e324eefb
+When
+.B PERF_SAMPLE_AUX
+flag is set,
+specify the desired size of AUX data.
+Note that it can get smaller data than the specified size.
+.TP
+.IR sig_data " (since Linux 5.13)"
+.\" commit 97ba62b278674293762c3d91f724f1bb922f04e0
+This data will be copied to user's signal handler
+(through
+.I si_perf
+in the
+.IR siginfo_t )
+to disambiguate which event triggered the signal.
+.SS Reading results
+Once a
+.BR perf_event_open ()
+file descriptor has been opened, the values
+of the events can be read from the file descriptor.
+The values that are there are specified by the
+.I read_format
+field in the
+.I attr
+structure at open time.
+.P
+If you attempt to read into a buffer that is not big enough to hold the
+data, the error
+.B ENOSPC
+results.
+.P
+Here is the layout of the data returned by a read:
+.IP \[bu] 3
+If
+.B PERF_FORMAT_GROUP
+was specified to allow reading all events in a group at once:
+.IP
+.in +4n
+.EX
+struct read_format {
+    u64 nr;            /* The number of events */
+    u64 time_enabled;  /* if PERF_FORMAT_TOTAL_TIME_ENABLED */
+    u64 time_running;  /* if PERF_FORMAT_TOTAL_TIME_RUNNING */
+    struct {
+        u64 value;     /* The value of the event */
+        u64 id;        /* if PERF_FORMAT_ID */
+        u64 lost;      /* if PERF_FORMAT_LOST */
+    } values[nr];
+};
+.EE
+.in
+.IP \[bu]
+If
+.B PERF_FORMAT_GROUP
+was
+.I not
+specified:
+.IP
+.in +4n
+.EX
+struct read_format {
+    u64 value;         /* The value of the event */
+    u64 time_enabled;  /* if PERF_FORMAT_TOTAL_TIME_ENABLED */
+    u64 time_running;  /* if PERF_FORMAT_TOTAL_TIME_RUNNING */
+    u64 id;            /* if PERF_FORMAT_ID */
+    u64 lost;          /* if PERF_FORMAT_LOST */
+};
+.EE
+.in
+.P
+The values read are as follows:
+.TP
+.I nr
+The number of events in this file descriptor.
+Available only if
+.B PERF_FORMAT_GROUP
+was specified.
+.TP
+.I time_enabled
+.TQ
+.I time_running
+Total time the event was enabled and running.
+Normally these values are the same.
+Multiplexing happens if the number of events is more than the
+number of available PMU counter slots.
+In that case the events run only part of the time and the
+.I time_enabled
+and
+.I time running
+values can be used to scale an estimated value for the count.
+.TP
+.I value
+An unsigned 64-bit value containing the counter result.
+.TP
+.I id
+A globally unique value for this particular event; only present if
+.B PERF_FORMAT_ID
+was specified in
+.IR read_format .
+.TP
+.I lost
+The number of lost samples of this event;
+only present if
+.B PERF_FORMAT_LOST
+was specified in
+.IR read_format .
+.SS MMAP layout
+When using
+.BR perf_event_open ()
+in sampled mode, asynchronous events
+(like counter overflow or
+.B PROT_EXEC
+mmap tracking)
+are logged into a ring-buffer.
+This ring-buffer is created and accessed through
+.BR mmap (2).
+.P
+The mmap size should be 1+2\[ha]n pages, where the first page is a
+metadata page
+.RI ( "struct perf_event_mmap_page" )
+that contains various
+bits of information such as where the ring-buffer head is.
+.P
+Before Linux 2.6.39, there is a bug that means you must allocate an mmap
+ring buffer when sampling even if you do not plan to access it.
+.P
+The structure of the first metadata mmap page is as follows:
+.P
+.in +4n
+.EX
+struct perf_event_mmap_page {
+    __u32 version;        /* version number of this structure */
+    __u32 compat_version; /* lowest version this is compat with */
+    __u32 lock;           /* seqlock for synchronization */
+    __u32 index;          /* hardware counter identifier */
+    __s64 offset;         /* add to hardware counter value */
+    __u64 time_enabled;   /* time event active */
+    __u64 time_running;   /* time event on CPU */
+    union {
+        __u64   capabilities;
+        struct {
+            __u64 cap_usr_time / cap_usr_rdpmc / cap_bit0 : 1,
+                  cap_bit0_is_deprecated : 1,
+                  cap_user_rdpmc         : 1,
+                  cap_user_time          : 1,
+                  cap_user_time_zero     : 1,
+        };
+    };
+    __u16 pmc_width;
+    __u16 time_shift;
+    __u32 time_mult;
+    __u64 time_offset;
+    __u64 __reserved[120];   /* Pad to 1 k */
+    __u64 data_head;         /* head in the data section */
+    __u64 data_tail;         /* user\-space written tail */
+    __u64 data_offset;       /* where the buffer starts */
+    __u64 data_size;         /* data buffer size */
+    __u64 aux_head;
+    __u64 aux_tail;
+    __u64 aux_offset;
+    __u64 aux_size;
+\&
+}
+.EE
+.in
+.P
+The following list describes the fields in the
+.I perf_event_mmap_page
+structure in more detail:
+.TP
+.I version
+Version number of this structure.
+.TP
+.I compat_version
+The lowest version this is compatible with.
+.TP
+.I lock
+A seqlock for synchronization.
+.TP
+.I index
+A unique hardware counter identifier.
+.TP
+.I offset
+When using rdpmc for reads this offset value
+must be added to the one returned by rdpmc to get
+the current total event count.
+.TP
+.I time_enabled
+Time the event was active.
+.TP
+.I time_running
+Time the event was running.
+.TP
+.IR cap_usr_time " / " cap_usr_rdpmc " / " cap_bit0 " (since Linux 3.4)"
+.\" commit c7206205d00ab375839bd6c7ddb247d600693c09
+There was a bug in the definition of
+.I cap_usr_time
+and
+.I cap_usr_rdpmc
+from Linux 3.4 until Linux 3.11.
+Both bits were defined to point to the same location, so it was
+impossible to know if
+.I cap_usr_time
+or
+.I cap_usr_rdpmc
+were actually set.
+.IP
+Starting with Linux 3.12, these are renamed to
+.\" commit fa7315871046b9a4c48627905691dbde57e51033
+.I cap_bit0
+and you should use the
+.I cap_user_time
+and
+.I cap_user_rdpmc
+fields instead.
+.TP
+.IR cap_bit0_is_deprecated " (since Linux 3.12)"
+.\" commit fa7315871046b9a4c48627905691dbde57e51033
+If set, this bit indicates that the kernel supports
+the properly separated
+.I cap_user_time
+and
+.I cap_user_rdpmc
+bits.
+.IP
+If not-set, it indicates an older kernel where
+.I cap_usr_time
+and
+.I cap_usr_rdpmc
+map to the same bit and thus both features should
+be used with caution.
+.TP
+.IR cap_user_rdpmc " (since Linux 3.12)"
+.\" commit fa7315871046b9a4c48627905691dbde57e51033
+If the hardware supports user-space read of performance counters
+without syscall (this is the "rdpmc" instruction on x86), then
+the following code can be used to do a read:
+.IP
+.in +4n
+.EX
+u32 seq, time_mult, time_shift, idx, width;
+u64 count, enabled, running;
+u64 cyc, time_offset;
+\&
+do {
+    seq = pc\->lock;
+    barrier();
+    enabled = pc\->time_enabled;
+    running = pc\->time_running;
+\&
+    if (pc\->cap_usr_time && enabled != running) {
+        cyc = rdtsc();
+        time_offset = pc\->time_offset;
+        time_mult   = pc\->time_mult;
+        time_shift  = pc\->time_shift;
+    }
+\&
+    idx = pc\->index;
+    count = pc\->offset;
+\&
+    if (pc\->cap_usr_rdpmc && idx) {
+        width = pc\->pmc_width;
+        count += rdpmc(idx \- 1);
+    }
+\&
+    barrier();
+} while (pc\->lock != seq);
+.EE
+.in
+.TP
+.IR cap_user_time " (since Linux 3.12)"
+.\" commit fa7315871046b9a4c48627905691dbde57e51033
+This bit indicates the hardware has a constant, nonstop
+timestamp counter (TSC on x86).
+.TP
+.IR cap_user_time_zero " (since Linux 3.12)"
+.\" commit fa7315871046b9a4c48627905691dbde57e51033
+Indicates the presence of
+.I time_zero
+which allows mapping timestamp values to
+the hardware clock.
+.TP
+.I pmc_width
+If
+.IR cap_usr_rdpmc ,
+this field provides the bit-width of the value
+read using the rdpmc or equivalent instruction.
+This can be used to sign extend the result like:
+.IP
+.in +4n
+.EX
+pmc <<= 64 \- pmc_width;
+pmc >>= 64 \- pmc_width; // signed shift right
+count += pmc;
+.EE
+.in
+.TP
+.I time_shift
+.TQ
+.I time_mult
+.TQ
+.I time_offset
+.IP
+If
+.IR cap_usr_time ,
+these fields can be used to compute the time
+delta since
+.I time_enabled
+(in nanoseconds) using rdtsc or similar.
+.IP
+.in +4n
+.EX
+u64 quot, rem;
+u64 delta;
+\&
+quot  = cyc >> time_shift;
+rem   = cyc & (((u64)1 << time_shift) \- 1);
+delta = time_offset + quot * time_mult +
+        ((rem * time_mult) >> time_shift);
+.EE
+.in
+.IP
+Where
+.IR time_offset ,
+.IR time_mult ,
+.IR time_shift ,
+and
+.I cyc
+are read in the
+seqcount loop described above.
+This delta can then be added to
+enabled and possible running (if idx), improving the scaling:
+.IP
+.in +4n
+.EX
+enabled += delta;
+if (idx)
+    running += delta;
+quot  = count / running;
+rem   = count % running;
+count = quot * enabled + (rem * enabled) / running;
+.EE
+.in
+.TP
+.IR time_zero " (since Linux 3.12)"
+.\" commit fa7315871046b9a4c48627905691dbde57e51033
+.IP
+If
+.I cap_usr_time_zero
+is set, then the hardware clock (the TSC timestamp counter on x86)
+can be calculated from the
+.IR time_zero ,
+.IR time_mult ,
+and
+.I time_shift
+values:
+.IP
+.in +4n
+.EX
+time = timestamp \- time_zero;
+quot = time / time_mult;
+rem  = time % time_mult;
+cyc  = (quot << time_shift) + (rem << time_shift) / time_mult;
+.EE
+.in
+.IP
+And vice versa:
+.IP
+.in +4n
+.EX
+quot = cyc >> time_shift;
+rem  = cyc & (((u64)1 << time_shift) \- 1);
+timestamp = time_zero + quot * time_mult +
+            ((rem * time_mult) >> time_shift);
+.EE
+.in
+.TP
+.I data_head
+This points to the head of the data section.
+The value continuously increases, it does not wrap.
+The value needs to be manually wrapped by the size of the mmap buffer
+before accessing the samples.
+.IP
+On SMP-capable platforms, after reading the
+.I data_head
+value,
+user space should issue an rmb().
+.TP
+.I data_tail
+When the mapping is
+.BR PROT_WRITE ,
+the
+.I data_tail
+value should be written by user space to reflect the last read data.
+In this case, the kernel will not overwrite unread data.
+.TP
+.IR data_offset " (since Linux 4.1)"
+.\" commit e8c6deac69629c0cb97c3d3272f8631ef17f8f0f
+Contains the offset of the location in the mmap buffer
+where perf sample data begins.
+.TP
+.IR data_size " (since Linux 4.1)"
+.\" commit e8c6deac69629c0cb97c3d3272f8631ef17f8f0f
+Contains the size of the perf sample region within
+the mmap buffer.
+.TP
+.I aux_head
+.TQ
+.I aux_tail
+.TQ
+.I aux_offset
+.TQ
+.I aux_size " (since Linux 4.1)"
+.\" commit 45bfb2e50471abbbfd83d40d28c986078b0d24ff
+The AUX region allows
+.BR mmap (2)-ing
+a separate sample buffer for
+high-bandwidth data streams (separate from the main perf sample buffer).
+An example of a high-bandwidth stream is instruction tracing support,
+as is found in newer Intel processors.
+.IP
+To set up an AUX area, first
+.I aux_offset
+needs to be set with an offset greater than
+.IR data_offset + data_size
+and
+.I aux_size
+needs to be set to the desired buffer size.
+The desired offset and size must be page aligned, and the size
+must be a power of two.
+These values are then passed to mmap in order to map the AUX buffer.
+Pages in the AUX buffer are included as part of the
+.B RLIMIT_MEMLOCK
+resource limit (see
+.BR setrlimit (2)),
+and also as part of the
+.I perf_event_mlock_kb
+allowance.
+.IP
+By default, the AUX buffer will be truncated if it will not fit
+in the available space in the ring buffer.
+If the AUX buffer is mapped as a read only buffer, then it will
+operate in ring buffer mode where old data will be overwritten
+by new.
+In overwrite mode, it might not be possible to infer where the
+new data began, and it is the consumer's job to disable
+measurement while reading to avoid possible data races.
+.IP
+The
+.I aux_head
+and
+.I aux_tail
+ring buffer pointers have the same behavior and ordering
+rules as the previous described
+.I data_head
+and
+.IR data_tail .
+.P
+The following 2^n ring-buffer pages have the layout described below.
+.P
+If
+.I perf_event_attr.sample_id_all
+is set, then all event types will
+have the sample_type selected fields related to where/when (identity)
+an event took place (TID, TIME, ID, CPU, STREAM_ID) described in
+.B PERF_RECORD_SAMPLE
+below, it will be stashed just after the
+.I perf_event_header
+and the fields already present for the existing
+fields, that is, at the end of the payload.
+This allows a newer perf.data
+file to be supported by older perf tools, with the new optional
+fields being ignored.
+.P
+The mmap values start with a header:
+.P
+.in +4n
+.EX
+struct perf_event_header {
+    __u32   type;
+    __u16   misc;
+    __u16   size;
+};
+.EE
+.in
+.P
+Below, we describe the
+.I perf_event_header
+fields in more detail.
+For ease of reading,
+the fields with shorter descriptions are presented first.
+.TP
+.I size
+This indicates the size of the record.
+.TP
+.I misc
+The
+.I misc
+field contains additional information about the sample.
+.IP
+The CPU mode can be determined from this value by masking with
+.B PERF_RECORD_MISC_CPUMODE_MASK
+and looking for one of the following (note these are not
+bit masks, only one can be set at a time):
+.RS
+.TP
+.B PERF_RECORD_MISC_CPUMODE_UNKNOWN
+Unknown CPU mode.
+.TP
+.B PERF_RECORD_MISC_KERNEL
+Sample happened in the kernel.
+.TP
+.B PERF_RECORD_MISC_USER
+Sample happened in user code.
+.TP
+.B PERF_RECORD_MISC_HYPERVISOR
+Sample happened in the hypervisor.
+.TP
+.BR PERF_RECORD_MISC_GUEST_KERNEL " (since Linux 2.6.35)"
+.\" commit 39447b386c846bbf1c56f6403c5282837486200f
+Sample happened in the guest kernel.
+.TP
+.B PERF_RECORD_MISC_GUEST_USER " (since Linux 2.6.35)"
+.\" commit 39447b386c846bbf1c56f6403c5282837486200f
+Sample happened in guest user code.
+.RE
+.P
+.RS
+Since the following three statuses are generated by
+different record types, they alias to the same bit:
+.TP
+.BR PERF_RECORD_MISC_MMAP_DATA " (since Linux 3.10)"
+.\" commit 2fe85427e3bf65d791700d065132772fc26e4d75
+This is set when the mapping is not executable;
+otherwise the mapping is executable.
+.TP
+.BR PERF_RECORD_MISC_COMM_EXEC " (since Linux 3.16)"
+.\" commit 82b897782d10fcc4930c9d4a15b175348fdd2871
+This is set for a
+.B PERF_RECORD_COMM
+record on kernels more recent than Linux 3.16
+if a process name change was caused by an
+.BR execve (2)
+system call.
+.TP
+.BR PERF_RECORD_MISC_SWITCH_OUT " (since Linux 4.3)"
+.\" commit 45ac1403f564f411c6a383a2448688ba8dd705a4
+When a
+.B PERF_RECORD_SWITCH
+or
+.B PERF_RECORD_SWITCH_CPU_WIDE
+record is generated, this bit indicates that the
+context switch is away from the current process
+(instead of into the current process).
+.RE
+.P
+.RS
+In addition, the following bits can be set:
+.TP
+.B PERF_RECORD_MISC_EXACT_IP
+This indicates that the content of
+.B PERF_SAMPLE_IP
+points
+to the actual instruction that triggered the event.
+See also
+.IR perf_event_attr.precise_ip .
+.TP
+.BR PERF_RECORD_MISC_SWITCH_OUT_PREEMPT " (since Linux 4.17)"
+.\" commit 101592b4904ecf6b8ed2a4784d41d180319d95a1
+When a
+.B PERF_RECORD_SWITCH
+or
+.B PERF_RECORD_SWITCH_CPU_WIDE
+record is generated,
+this indicates the context switch was a preemption.
+.TP
+.BR PERF_RECORD_MISC_MMAP_BUILD_ID " (since Linux 5.12)"
+.\" commit 88a16a1309333e43d328621ece3e9fa37027e8eb
+This indicates that the content of
+.B PERF_SAMPLE_MMAP2
+contains build-ID data instead of device major and minor numbers
+as well as the inode number.
+.TP
+.BR PERF_RECORD_MISC_EXT_RESERVED " (since Linux 2.6.35)"
+.\" commit 1676b8a077c352085d52578fb4f29350b58b6e74
+This indicates there is extended data available (currently not used).
+.TP
+.B PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT
+.\" commit 930e6fcd2bcce9bcd9d4aa7e755678d33f3fe6f4
+This bit is not set by the kernel.
+It is reserved for the user-space perf utility to indicate that
+.IR /proc/ pid /maps
+parsing was taking too long and was stopped, and thus the mmap
+records may be truncated.
+.RE
+.TP
+.I type
+The
+.I type
+value is one of the below.
+The values in the corresponding record (that follows the header)
+depend on the
+.I type
+selected as shown.
+.RS
+.TP 4
+.B PERF_RECORD_MMAP
+The MMAP events record the
+.B PROT_EXEC
+mappings so that we can correlate
+user-space IPs to code.
+They have the following structure:
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid, tid;
+    u64    addr;
+    u64    len;
+    u64    pgoff;
+    char   filename[];
+};
+.EE
+.in
+.RS
+.TP
+.I pid
+is the process ID.
+.TP
+.I tid
+is the thread ID.
+.TP
+.I addr
+is the address of the allocated memory.
+.I len
+is the length of the allocated memory.
+.I pgoff
+is the page offset of the allocated memory.
+.I filename
+is a string describing the backing of the allocated memory.
+.RE
+.TP
+.B PERF_RECORD_LOST
+This record indicates when events are lost.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    id;
+    u64    lost;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I id
+is the unique event ID for the samples that were lost.
+.TP
+.I lost
+is the number of events that were lost.
+.RE
+.TP
+.B PERF_RECORD_COMM
+This record indicates a change in the process name.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid;
+    u32    tid;
+    char   comm[];
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I pid
+is the process ID.
+.TP
+.I tid
+is the thread ID.
+.TP
+.I comm
+is a string containing the new name of the process.
+.RE
+.TP
+.B PERF_RECORD_EXIT
+This record indicates a process exit event.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid, ppid;
+    u32    tid, ptid;
+    u64    time;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.TP
+.B PERF_RECORD_THROTTLE
+.TQ
+.B PERF_RECORD_UNTHROTTLE
+This record indicates a throttle/unthrottle event.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    time;
+    u64    id;
+    u64    stream_id;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.TP
+.B PERF_RECORD_FORK
+This record indicates a fork event.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid, ppid;
+    u32    tid, ptid;
+    u64    time;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.TP
+.B PERF_RECORD_READ
+This record indicates a read event.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid, tid;
+    struct read_format values;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.TP
+.B PERF_RECORD_SAMPLE
+This record indicates a sample.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    sample_id;   /* if PERF_SAMPLE_IDENTIFIER */
+    u64    ip;          /* if PERF_SAMPLE_IP */
+    u32    pid, tid;    /* if PERF_SAMPLE_TID */
+    u64    time;        /* if PERF_SAMPLE_TIME */
+    u64    addr;        /* if PERF_SAMPLE_ADDR */
+    u64    id;          /* if PERF_SAMPLE_ID */
+    u64    stream_id;   /* if PERF_SAMPLE_STREAM_ID */
+    u32    cpu, res;    /* if PERF_SAMPLE_CPU */
+    u64    period;      /* if PERF_SAMPLE_PERIOD */
+    struct read_format v;
+                        /* if PERF_SAMPLE_READ */
+    u64    nr;          /* if PERF_SAMPLE_CALLCHAIN */
+    u64    ips[nr];     /* if PERF_SAMPLE_CALLCHAIN */
+    u32    size;        /* if PERF_SAMPLE_RAW */
+    char   data[size];  /* if PERF_SAMPLE_RAW */
+    u64    bnr;         /* if PERF_SAMPLE_BRANCH_STACK */
+    struct perf_branch_entry lbr[bnr];
+                        /* if PERF_SAMPLE_BRANCH_STACK */
+    u64    abi;         /* if PERF_SAMPLE_REGS_USER */
+    u64    regs[weight(mask)];
+                        /* if PERF_SAMPLE_REGS_USER */
+    u64    size;        /* if PERF_SAMPLE_STACK_USER */
+    char   data[size];  /* if PERF_SAMPLE_STACK_USER */
+    u64    dyn_size;    /* if PERF_SAMPLE_STACK_USER &&
+                           size != 0 */
+    union perf_sample_weight weight;
+                        /* if PERF_SAMPLE_WEIGHT */
+                        /* || PERF_SAMPLE_WEIGHT_STRUCT */
+    u64    data_src;    /* if PERF_SAMPLE_DATA_SRC */
+    u64    transaction; /* if PERF_SAMPLE_TRANSACTION */
+    u64    abi;         /* if PERF_SAMPLE_REGS_INTR */
+    u64    regs[weight(mask)];
+                        /* if PERF_SAMPLE_REGS_INTR */
+    u64    phys_addr;   /* if PERF_SAMPLE_PHYS_ADDR */
+    u64    cgroup;      /* if PERF_SAMPLE_CGROUP */
+    u64    data_page_size;
+                      /* if PERF_SAMPLE_DATA_PAGE_SIZE */
+    u64    code_page_size;
+                      /* if PERF_SAMPLE_CODE_PAGE_SIZE */
+    u64    size;        /* if PERF_SAMPLE_AUX */
+    char   data[size];  /* if PERF_SAMPLE_AUX */
+};
+.EE
+.in
+.RS 4
+.TP 4
+.I sample_id
+If
+.B PERF_SAMPLE_IDENTIFIER
+is enabled, a 64-bit unique ID is included.
+This is a duplication of the
+.B PERF_SAMPLE_ID
+.I id
+value, but included at the beginning of the sample
+so parsers can easily obtain the value.
+.TP
+.I ip
+If
+.B PERF_SAMPLE_IP
+is enabled, then a 64-bit instruction
+pointer value is included.
+.TP
+.I pid
+.TQ
+.I tid
+If
+.B PERF_SAMPLE_TID
+is enabled, then a 32-bit process ID
+and 32-bit thread ID are included.
+.TP
+.I time
+If
+.B PERF_SAMPLE_TIME
+is enabled, then a 64-bit timestamp
+is included.
+This is obtained via local_clock() which is a hardware timestamp
+if available and the jiffies value if not.
+.TP
+.I addr
+If
+.B PERF_SAMPLE_ADDR
+is enabled, then a 64-bit address is included.
+This is usually the address of a tracepoint,
+breakpoint, or software event; otherwise the value is 0.
+.TP
+.I id
+If
+.B PERF_SAMPLE_ID
+is enabled, a 64-bit unique ID is included.
+If the event is a member of an event group, the group leader ID is returned.
+This ID is the same as the one returned by
+.BR PERF_FORMAT_ID .
+.TP
+.I stream_id
+If
+.B PERF_SAMPLE_STREAM_ID
+is enabled, a 64-bit unique ID is included.
+Unlike
+.B PERF_SAMPLE_ID
+the actual ID is returned, not the group leader.
+This ID is the same as the one returned by
+.BR PERF_FORMAT_ID .
+.TP
+.I cpu
+.TQ
+.I res
+If
+.B PERF_SAMPLE_CPU
+is enabled, this is a 32-bit value indicating
+which CPU was being used, in addition to a reserved (unused)
+32-bit value.
+.TP
+.I period
+If
+.B PERF_SAMPLE_PERIOD
+is enabled, a 64-bit value indicating
+the current sampling period is written.
+.TP
+.I v
+If
+.B PERF_SAMPLE_READ
+is enabled, a structure of type read_format
+is included which has values for all events in the event group.
+The values included depend on the
+.I read_format
+value used at
+.BR perf_event_open ()
+time.
+.TP
+.I nr
+.TQ
+.I ips[nr]
+If
+.B PERF_SAMPLE_CALLCHAIN
+is enabled, then a 64-bit number is included
+which indicates how many following 64-bit instruction pointers will
+follow.
+This is the current callchain.
+.TP
+.I size
+.TQ
+.I data[size]
+If
+.B PERF_SAMPLE_RAW
+is enabled, then a 32-bit value indicating size
+is included followed by an array of 8-bit values of length size.
+The values are padded with 0 to have 64-bit alignment.
+.IP
+This RAW record data is opaque with respect to the ABI.
+The ABI doesn't make any promises with respect to the stability
+of its content, it may vary depending
+on event, hardware, and kernel version.
+.TP
+.I bnr
+.TQ
+.I lbr[bnr]
+If
+.B PERF_SAMPLE_BRANCH_STACK
+is enabled, then a 64-bit value indicating
+the number of records is included, followed by
+.I bnr
+.I perf_branch_entry
+structures which each include the fields:
+.RS
+.TP
+.I from
+This indicates the source instruction (may not be a branch).
+.TP
+.I to
+The branch target.
+.TP
+.I mispred
+The branch target was mispredicted.
+.TP
+.I predicted
+The branch target was predicted.
+.TP
+.IR in_tx " (since Linux 3.11)"
+.\" commit 135c5612c460f89657c4698fe2ea753f6f667963
+The branch was in a transactional memory transaction.
+.TP
+.IR abort " (since Linux 3.11)"
+.\" commit 135c5612c460f89657c4698fe2ea753f6f667963
+The branch was in an aborted transactional memory transaction.
+.TP
+.IR cycles " (since Linux 4.3)"
+.\" commit 71ef3c6b9d4665ee7afbbe4c208a98917dcfc32f
+This reports the number of cycles elapsed since the
+previous branch stack update.
+.P
+The entries are from most to least recent, so the first entry
+has the most recent branch.
+.P
+Support for
+.IR mispred ,
+.IR predicted ,
+and
+.I cycles
+is optional; if not supported, those
+values will be 0.
+.P
+The type of branches recorded is specified by the
+.I branch_sample_type
+field.
+.RE
+.TP
+.I abi
+.TQ
+.I regs[weight(mask)]
+If
+.B PERF_SAMPLE_REGS_USER
+is enabled, then the user CPU registers are recorded.
+.IP
+The
+.I abi
+field is one of
+.BR PERF_SAMPLE_REGS_ABI_NONE ,
+.BR PERF_SAMPLE_REGS_ABI_32 ,
+or
+.BR PERF_SAMPLE_REGS_ABI_64 .
+.IP
+The
+.I regs
+field is an array of the CPU registers that were specified by
+the
+.I sample_regs_user
+attr field.
+The number of values is the number of bits set in the
+.I sample_regs_user
+bit mask.
+.TP
+.I size
+.TQ
+.I data[size]
+.TQ
+.I dyn_size
+If
+.B PERF_SAMPLE_STACK_USER
+is enabled, then the user stack is recorded.
+This can be used to generate stack backtraces.
+.I size
+is the size requested by the user in
+.I sample_stack_user
+or else the maximum record size.
+.I data
+is the stack data (a raw dump of the memory pointed to by the
+stack pointer at the time of sampling).
+.I dyn_size
+is the amount of data actually dumped (can be less than
+.IR size ).
+Note that
+.I dyn_size
+is omitted if
+.I size
+is 0.
+.TP
+.I weight
+If
+.B PERF_SAMPLE_WEIGHT
+or
+.B PERF_SAMPLE_WEIGHT_STRUCT
+is enabled, then a 64-bit value provided by the hardware
+is recorded that indicates how costly the event was.
+This allows expensive events to stand out more clearly
+in profiles.
+.TP
+.I data_src
+If
+.B PERF_SAMPLE_DATA_SRC
+is enabled, then a 64-bit value is recorded that is made up of
+the following fields:
+.RS
+.TP 4
+.I mem_op
+Type of opcode, a bitwise combination of:
+.IP
+.PD 0
+.RS
+.TP 24
+.B PERF_MEM_OP_NA
+Not available
+.TP
+.B PERF_MEM_OP_LOAD
+Load instruction
+.TP
+.B PERF_MEM_OP_STORE
+Store instruction
+.TP
+.B PERF_MEM_OP_PFETCH
+Prefetch
+.TP
+.B PERF_MEM_OP_EXEC
+Executable code
+.RE
+.PD
+.TP
+.I mem_lvl
+Memory hierarchy level hit or miss, a bitwise combination of
+the following, shifted left by
+.BR PERF_MEM_LVL_SHIFT :
+.IP
+.PD 0
+.RS
+.TP 24
+.B PERF_MEM_LVL_NA
+Not available
+.TP
+.B PERF_MEM_LVL_HIT
+Hit
+.TP
+.B PERF_MEM_LVL_MISS
+Miss
+.TP
+.B PERF_MEM_LVL_L1
+Level 1 cache
+.TP
+.B PERF_MEM_LVL_LFB
+Line fill buffer
+.TP
+.B PERF_MEM_LVL_L2
+Level 2 cache
+.TP
+.B PERF_MEM_LVL_L3
+Level 3 cache
+.TP
+.B PERF_MEM_LVL_LOC_RAM
+Local DRAM
+.TP
+.B PERF_MEM_LVL_REM_RAM1
+Remote DRAM 1 hop
+.TP
+.B PERF_MEM_LVL_REM_RAM2
+Remote DRAM 2 hops
+.TP
+.B PERF_MEM_LVL_REM_CCE1
+Remote cache 1 hop
+.TP
+.B PERF_MEM_LVL_REM_CCE2
+Remote cache 2 hops
+.TP
+.B PERF_MEM_LVL_IO
+I/O memory
+.TP
+.B PERF_MEM_LVL_UNC
+Uncached memory
+.RE
+.PD
+.TP
+.I mem_snoop
+Snoop mode, a bitwise combination of the following, shifted left by
+.BR PERF_MEM_SNOOP_SHIFT :
+.IP
+.PD 0
+.RS
+.TP 24
+.B PERF_MEM_SNOOP_NA
+Not available
+.TP
+.B PERF_MEM_SNOOP_NONE
+No snoop
+.TP
+.B PERF_MEM_SNOOP_HIT
+Snoop hit
+.TP
+.B PERF_MEM_SNOOP_MISS
+Snoop miss
+.TP
+.B PERF_MEM_SNOOP_HITM
+Snoop hit modified
+.RE
+.PD
+.TP
+.I mem_lock
+Lock instruction, a bitwise combination of the following, shifted left by
+.BR PERF_MEM_LOCK_SHIFT :
+.IP
+.PD 0
+.RS
+.TP 24
+.B PERF_MEM_LOCK_NA
+Not available
+.TP
+.B PERF_MEM_LOCK_LOCKED
+Locked transaction
+.RE
+.PD
+.TP
+.I mem_dtlb
+TLB access hit or miss, a bitwise combination of the following, shifted
+left by
+.BR PERF_MEM_TLB_SHIFT :
+.IP
+.PD 0
+.RS
+.TP 24
+.B PERF_MEM_TLB_NA
+Not available
+.TP
+.B PERF_MEM_TLB_HIT
+Hit
+.TP
+.B PERF_MEM_TLB_MISS
+Miss
+.TP
+.B PERF_MEM_TLB_L1
+Level 1 TLB
+.TP
+.B PERF_MEM_TLB_L2
+Level 2 TLB
+.TP
+.B PERF_MEM_TLB_WK
+Hardware walker
+.TP
+.B PERF_MEM_TLB_OS
+OS fault handler
+.RE
+.PD
+.RE
+.TP
+.I transaction
+If the
+.B PERF_SAMPLE_TRANSACTION
+flag is set, then a 64-bit field is recorded describing
+the sources of any transactional memory aborts.
+.IP
+The field is a bitwise combination of the following values:
+.RS
+.TP
+.B PERF_TXN_ELISION
+Abort from an elision type transaction (Intel-CPU-specific).
+.TP
+.B PERF_TXN_TRANSACTION
+Abort from a generic transaction.
+.TP
+.B PERF_TXN_SYNC
+Synchronous abort (related to the reported instruction).
+.TP
+.B PERF_TXN_ASYNC
+Asynchronous abort (not related to the reported instruction).
+.TP
+.B PERF_TXN_RETRY
+Retryable abort (retrying the transaction may have succeeded).
+.TP
+.B PERF_TXN_CONFLICT
+Abort due to memory conflicts with other threads.
+.TP
+.B PERF_TXN_CAPACITY_WRITE
+Abort due to write capacity overflow.
+.TP
+.B PERF_TXN_CAPACITY_READ
+Abort due to read capacity overflow.
+.RE
+.IP
+In addition, a user-specified abort code can be obtained from
+the high 32 bits of the field by shifting right by
+.B PERF_TXN_ABORT_SHIFT
+and masking with the value
+.BR PERF_TXN_ABORT_MASK .
+.TP
+.I abi
+.TQ
+.I regs[weight(mask)]
+If
+.B PERF_SAMPLE_REGS_INTR
+is enabled, then the user CPU registers are recorded.
+.IP
+The
+.I abi
+field is one of
+.BR PERF_SAMPLE_REGS_ABI_NONE ,
+.BR PERF_SAMPLE_REGS_ABI_32 ,
+or
+.BR PERF_SAMPLE_REGS_ABI_64 .
+.IP
+The
+.I regs
+field is an array of the CPU registers that were specified by
+the
+.I sample_regs_intr
+attr field.
+The number of values is the number of bits set in the
+.I sample_regs_intr
+bit mask.
+.TP
+.I phys_addr
+If the
+.B PERF_SAMPLE_PHYS_ADDR
+flag is set, then the 64-bit physical address is recorded.
+.TP
+.I cgroup
+If the
+.B PERF_SAMPLE_CGROUP
+flag is set,
+then the 64-bit cgroup ID (for the perf_event subsystem) is recorded.
+To get the pathname of the cgroup, the ID should match to one in a
+.BR PERF_RECORD_CGROUP .
+.TP
+.I data_page_size
+If the
+.B PERF_SAMPLE_DATA_PAGE_SIZE
+flag is set,
+then the 64-bit page size value of the
+.B data
+address is recorded.
+.TP
+.I code_page_size
+If the
+.B PERF_SAMPLE_CODE_PAGE_SIZE
+flag is set,
+then the 64-bit page size value of the
+.B ip
+address is recorded.
+.TP
+.I size
+.TQ
+.IR data [ size ]
+If
+.B PERF_SAMPLE_AUX
+is enabled,
+a snapshot of the aux buffer is recorded.
+.RE
+.TP
+.B PERF_RECORD_MMAP2
+This record includes extended information on
+.BR mmap (2)
+calls returning executable mappings.
+The format is similar to that of the
+.B PERF_RECORD_MMAP
+record, but includes extra values that allow uniquely identifying
+shared mappings.
+Depending on the
+.B PERF_RECORD_MISC_MMAP_BUILD_ID
+bit in the header,
+the extra values have different layout and meanings.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid;
+    u32    tid;
+    u64    addr;
+    u64    len;
+    u64    pgoff;
+    union {
+        struct {
+            u32    maj;
+            u32    min;
+            u64    ino;
+            u64    ino_generation;
+        };
+        struct {   /* if PERF_RECORD_MISC_MMAP_BUILD_ID */
+            u8     build_id_size;
+            u8     __reserved_1;
+            u16    __reserved_2;
+            u8     build_id[20];
+        };
+    };
+    u32    prot;
+    u32    flags;
+    char   filename[];
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I pid
+is the process ID.
+.TP
+.I tid
+is the thread ID.
+.TP
+.I addr
+is the address of the allocated memory.
+.TP
+.I len
+is the length of the allocated memory.
+.TP
+.I pgoff
+is the page offset of the allocated memory.
+.TP
+.I maj
+is the major ID of the underlying device.
+.TP
+.I min
+is the minor ID of the underlying device.
+.TP
+.I ino
+is the inode number.
+.TP
+.I ino_generation
+is the inode generation.
+.TP
+.I build_id_size
+is the actual size of
+.I build_id
+field (up to 20).
+.TP
+.I build_id
+is a raw data to identify a binary.
+.TP
+.I prot
+is the protection information.
+.TP
+.I flags
+is the flags information.
+.TP
+.I filename
+is a string describing the backing of the allocated memory.
+.RE
+.TP
+.BR PERF_RECORD_AUX " (since Linux 4.1)"
+.\" commit 68db7e98c3a6ebe7284b6cf14906ed7c55f3f7f0
+This record reports that new data is available in the separate
+AUX buffer region.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    aux_offset;
+    u64    aux_size;
+    u64    flags;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I aux_offset
+offset in the AUX mmap region where the new data begins.
+.TP
+.I aux_size
+size of the data made available.
+.TP
+.I flags
+describes the AUX update.
+.RS
+.TP
+.B PERF_AUX_FLAG_TRUNCATED
+if set, then the data returned was truncated to fit the available
+buffer size.
+.TP
+.B PERF_AUX_FLAG_OVERWRITE
+.\" commit 2023a0d2829e521fe6ad6b9907f3f90bfbf57142
+if set, then the data returned has overwritten previous data.
+.RE
+.RE
+.TP
+.BR PERF_RECORD_ITRACE_START " (since Linux 4.1)"
+.\" ec0d7729bbaed4b9d2d3fada693278e13a3d1368
+This record indicates which process has initiated an instruction
+trace event, allowing tools to properly correlate the instruction
+addresses in the AUX buffer with the proper executable.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid;
+    u32    tid;
+};
+.EE
+.in
+.RS
+.TP
+.I pid
+process ID of the thread starting an instruction trace.
+.TP
+.I tid
+thread ID of the thread starting an instruction trace.
+.RE
+.TP
+.BR PERF_RECORD_LOST_SAMPLES " (since Linux 4.2)"
+.\" f38b0dbb491a6987e198aa6b428db8692a6480f8
+When using hardware sampling (such as Intel PEBS) this record
+indicates some number of samples that may have been lost.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    lost;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I lost
+the number of potentially lost samples.
+.RE
+.TP
+.BR PERF_RECORD_SWITCH " (since Linux 4.3)"
+.\" commit 45ac1403f564f411c6a383a2448688ba8dd705a4
+This record indicates a context switch has happened.
+The
+.B PERF_RECORD_MISC_SWITCH_OUT
+bit in the
+.I misc
+field indicates whether it was a context switch into
+or away from the current process.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.TP
+.BR PERF_RECORD_SWITCH_CPU_WIDE " (since Linux 4.3)"
+.\" commit 45ac1403f564f411c6a383a2448688ba8dd705a4
+As with
+.B PERF_RECORD_SWITCH
+this record indicates a context switch has happened,
+but it only occurs when sampling in CPU-wide mode
+and provides additional information on the process
+being switched to/from.
+The
+.B PERF_RECORD_MISC_SWITCH_OUT
+bit in the
+.I misc
+field indicates whether it was a context switch into
+or away from the current process.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32 next_prev_pid;
+    u32 next_prev_tid;
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I next_prev_pid
+The process ID of the previous (if switching in)
+or next (if switching out) process on the CPU.
+.TP
+.I next_prev_tid
+The thread ID of the previous (if switching in)
+or next (if switching out) thread on the CPU.
+.RE
+.TP
+.BR PERF_RECORD_NAMESPACES " (since Linux 4.11)"
+.\" commit e422267322cd319e2695a535e47c5b1feeac45eb
+This record includes various namespace information of a process.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u32    pid;
+    u32    tid;
+    u64    nr_namespaces;
+    struct { u64 dev, inode } [nr_namespaces];
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I pid
+is the process ID
+.TP
+.I tid
+is the thread ID
+.TP
+.I nr_namespace
+is the number of namespaces in this record
+.RE
+.IP
+Each namespace has
+.I dev
+and
+.I inode
+fields and is recorded in the
+fixed position like below:
+.RS
+.TP
+.BR NET_NS_INDEX = 0
+Network namespace
+.TP
+.BR UTS_NS_INDEX = 1
+UTS namespace
+.TP
+.BR IPC_NS_INDEX = 2
+IPC namespace
+.TP
+.BR PID_NS_INDEX = 3
+PID namespace
+.TP
+.BR USER_NS_INDEX = 4
+User namespace
+.TP
+.BR MNT_NS_INDEX = 5
+Mount namespace
+.TP
+.BR CGROUP_NS_INDEX = 6
+Cgroup namespace
+.RE
+.TP
+.BR PERF_RECORD_KSYMBOL " (since Linux 5.0)"
+.\" commit 76193a94522f1d4edf2447a536f3f796ce56343b
+This record indicates kernel symbol register/unregister events.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    addr;
+    u32    len;
+    u16    ksym_type;
+    u16    flags;
+    char   name[];
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I addr
+is the address of the kernel symbol.
+.TP
+.I len
+is the length of the kernel symbol.
+.TP
+.I ksym_type
+is the type of the kernel symbol.
+Currently the following types are available:
+.RS
+.TP
+.B PERF_RECORD_KSYMBOL_TYPE_BPF
+The kernel symbol is a BPF function.
+.RE
+.TP
+.I flags
+If the
+.B PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER
+is set, then this event is for unregistering the kernel symbol.
+.RE
+.TP
+.BR PERF_RECORD_BPF_EVENT " (since Linux 5.0)"
+.\" commit 6ee52e2a3fe4ea35520720736e6791df1fb67106
+This record indicates BPF program is loaded or unloaded.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u16 type;
+    u16 flags;
+    u32 id;
+    u8 tag[BPF_TAG_SIZE];
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I type
+is one of the following values:
+.RS
+.TP
+.B PERF_BPF_EVENT_PROG_LOAD
+A BPF program is loaded
+.TP
+.B PERF_BPF_EVENT_PROG_UNLOAD
+A BPF program is unloaded
+.RE
+.TP
+.I id
+is the ID of the BPF program.
+.TP
+.I tag
+is the tag of the BPF program.
+Currently,
+.B BPF_TAG_SIZE
+is defined as 8.
+.RE
+.TP
+.BR PERF_RECORD_CGROUP " (since Linux 5.7)"
+.\" commit 96aaab686505c449e24d76e76507290dcc30e008
+This record indicates a new cgroup is created and activated.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    id;
+    char   path[];
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I id
+is the cgroup identifier.
+This can be also retrieved by
+.BR name_to_handle_at (2)
+on the cgroup path (as a file handle).
+.TP
+.I path
+is the path of the cgroup from the root.
+.RE
+.TP
+.BR PERF_RECORD_TEXT_POKE " (since Linux 5.8)"
+.\" commit e17d43b93e544f5016c0251d2074c15568d5d963
+This record indicates a change in the kernel text.
+This includes addition and removal of the text
+and the corresponding length is zero in this case.
+.IP
+.in +4n
+.EX
+struct {
+    struct perf_event_header header;
+    u64    addr;
+    u16    old_len;
+    u16    new_len;
+    u8     bytes[];
+    struct sample_id sample_id;
+};
+.EE
+.in
+.RS
+.TP
+.I addr
+is the address of the change
+.TP
+.I old_len
+is the old length
+.TP
+.I new_len
+is the new length
+.TP
+.I bytes
+contains old bytes immediately followed by new bytes.
+.RE
+.RE
+.SS Overflow handling
+Events can be set to notify when a threshold is crossed,
+indicating an overflow.
+Overflow conditions can be captured by monitoring the
+event file descriptor with
+.BR poll (2),
+.BR select (2),
+or
+.BR epoll (7).
+Alternatively, the overflow events can be captured via sa signal handler,
+by enabling I/O signaling on the file descriptor; see the discussion of the
+.B F_SETOWN
+and
+.B F_SETSIG
+operations in
+.BR fcntl (2).
+.P
+Overflows are generated only by sampling events
+.RI ( sample_period
+must have a nonzero value).
+.P
+There are two ways to generate overflow notifications.
+.P
+The first is to set a
+.I wakeup_events
+or
+.I wakeup_watermark
+value that will trigger if a certain number of samples
+or bytes have been written to the mmap ring buffer.
+In this case,
+.B POLL_IN
+is indicated.
+.P
+The other way is by use of the
+.B PERF_EVENT_IOC_REFRESH
+ioctl.
+This ioctl adds to a counter that decrements each time the event overflows.
+When nonzero,
+.B POLL_IN
+is indicated, but
+once the counter reaches 0
+.B POLL_HUP
+is indicated and
+the underlying event is disabled.
+.P
+Refreshing an event group leader refreshes all siblings and
+refreshing with a parameter of 0 currently enables infinite
+refreshes;
+these behaviors are unsupported and should not be relied on.
+.\" See https://lkml.org/lkml/2011/5/24/337
+.P
+Starting with Linux 3.18,
+.\" commit 179033b3e064d2cd3f5f9945e76b0a0f0fbf4883
+.B POLL_HUP
+is indicated if the event being monitored is attached to a different
+process and that process exits.
+.SS rdpmc instruction
+Starting with Linux 3.4 on x86, you can use the
+.\" commit c7206205d00ab375839bd6c7ddb247d600693c09
+.I rdpmc
+instruction to get low-latency reads without having to enter the kernel.
+Note that using
+.I rdpmc
+is not necessarily faster than other methods for reading event values.
+.P
+Support for this can be detected with the
+.I cap_usr_rdpmc
+field in the mmap page; documentation on how
+to calculate event values can be found in that section.
+.P
+Originally, when rdpmc support was enabled, any process (not just ones
+with an active perf event) could use the rdpmc instruction to access
+the counters.
+Starting with Linux 4.0,
+.\" 7911d3f7af14a614617e38245fedf98a724e46a9
+rdpmc support is only allowed if an event is currently enabled
+in a process's context.
+To restore the old behavior, write the value 2 to
+.IR /sys/devices/cpu/rdpmc .
+.SS perf_event ioctl calls
+Various ioctls act on
+.BR perf_event_open ()
+file descriptors:
+.TP
+.B PERF_EVENT_IOC_ENABLE
+This enables the individual event or event group specified by the
+file descriptor argument.
+.IP
+If the
+.B PERF_IOC_FLAG_GROUP
+bit is set in the ioctl argument, then all events in a group are
+enabled, even if the event specified is not the group leader
+(but see BUGS).
+.TP
+.B PERF_EVENT_IOC_DISABLE
+This disables the individual counter or event group specified by the
+file descriptor argument.
+.IP
+Enabling or disabling the leader of a group enables or disables the
+entire group; that is, while the group leader is disabled, none of the
+counters in the group will count.
+Enabling or disabling a member of a group other than the leader
+affects only that counter; disabling a non-leader
+stops that counter from counting but doesn't affect any other counter.
+.IP
+If the
+.B PERF_IOC_FLAG_GROUP
+bit is set in the ioctl argument, then all events in a group are
+disabled, even if the event specified is not the group leader
+(but see BUGS).
+.TP
+.B PERF_EVENT_IOC_REFRESH
+Non-inherited overflow counters can use this
+to enable a counter for a number of overflows specified by the argument,
+after which it is disabled.
+Subsequent calls of this ioctl add the argument value to the current
+count.
+An overflow notification with
+.B POLL_IN
+set will happen on each overflow until the
+count reaches 0; when that happens a notification with
+.B POLL_HUP
+set is sent and the event is disabled.
+Using an argument of 0 is considered undefined behavior.
+.TP
+.B PERF_EVENT_IOC_RESET
+Reset the event count specified by the
+file descriptor argument to zero.
+This resets only the counts; there is no way to reset the
+multiplexing
+.I time_enabled
+or
+.I time_running
+values.
+.IP
+If the
+.B PERF_IOC_FLAG_GROUP
+bit is set in the ioctl argument, then all events in a group are
+reset, even if the event specified is not the group leader
+(but see BUGS).
+.TP
+.B PERF_EVENT_IOC_PERIOD
+This updates the overflow period for the event.
+.IP
+Since Linux 3.7 (on ARM)
+.\" commit 3581fe0ef37ce12ac7a4f74831168352ae848edc
+and Linux 3.14 (all other architectures),
+.\" commit bad7192b842c83e580747ca57104dd51fe08c223
+the new period takes effect immediately.
+On older kernels, the new period did not take effect until
+after the next overflow.
+.IP
+The argument is a pointer to a 64-bit value containing the
+desired new period.
+.IP
+Prior to Linux 2.6.36,
+.\" commit ad0cf3478de8677f720ee06393b3147819568d6a
+this ioctl always failed due to a bug
+in the kernel.
+.TP
+.B PERF_EVENT_IOC_SET_OUTPUT
+This tells the kernel to report event notifications to the specified
+file descriptor rather than the default one.
+The file descriptors must all be on the same CPU.
+.IP
+The argument specifies the desired file descriptor, or \-1 if
+output should be ignored.
+.TP
+.BR PERF_EVENT_IOC_SET_FILTER " (since Linux 2.6.33)"
+.\" commit 6fb2915df7f0747d9044da9dbff5b46dc2e20830
+This adds an ftrace filter to this event.
+.IP
+The argument is a pointer to the desired ftrace filter.
+.TP
+.BR PERF_EVENT_IOC_ID " (since Linux 3.12)"
+.\" commit cf4957f17f2a89984915ea808876d9c82225b862
+This returns the event ID value for the given event file descriptor.
+.IP
+The argument is a pointer to a 64-bit unsigned integer
+to hold the result.
+.TP
+.BR PERF_EVENT_IOC_SET_BPF " (since Linux 4.1)"
+.\" commit 2541517c32be2531e0da59dfd7efc1ce844644f5
+This allows attaching a Berkeley Packet Filter (BPF)
+program to an existing kprobe tracepoint event.
+You need
+.B CAP_PERFMON
+(since Linux 5.8) or
+.B CAP_SYS_ADMIN
+privileges to use this ioctl.
+.IP
+The argument is a BPF program file descriptor that was created by
+a previous
+.BR bpf (2)
+system call.
+.TP
+.BR PERF_EVENT_IOC_PAUSE_OUTPUT " (since Linux 4.7)"
+.\" commit 86e7972f690c1017fd086cdfe53d8524e68c661c
+This allows pausing and resuming the event's ring-buffer.
+A paused ring-buffer does not prevent generation of samples,
+but simply discards them.
+The discarded samples are considered lost, and cause a
+.B PERF_RECORD_LOST
+sample to be generated when possible.
+An overflow signal may still be triggered by the discarded sample
+even though the ring-buffer remains empty.
+.IP
+The argument is an unsigned 32-bit integer.
+A nonzero value pauses the ring-buffer, while a
+zero value resumes the ring-buffer.
+.TP
+.BR PERF_EVENT_MODIFY_ATTRIBUTES " (since Linux 4.17)"
+.\" commit 32ff77e8cc9e66cc4fb38098f64fd54cc8f54573
+This allows modifying an existing event without the overhead
+of closing and reopening a new event.
+Currently this is supported only for breakpoint events.
+.IP
+The argument is a pointer to a
+.I perf_event_attr
+structure containing the updated event settings.
+.TP
+.BR PERF_EVENT_IOC_QUERY_BPF " (since Linux 4.16)"
+.\" commit f371b304f12e31fe30207c41ca7754564e0ea4dc
+This allows querying which Berkeley Packet Filter (BPF)
+programs are attached to an existing kprobe tracepoint.
+You can only attach one BPF program per event, but you can
+have multiple events attached to a tracepoint.
+Querying this value on one tracepoint event returns the ID
+of all BPF programs in all events attached to the tracepoint.
+You need
+.B CAP_PERFMON
+(since Linux 5.8) or
+.B CAP_SYS_ADMIN
+privileges to use this ioctl.
+.IP
+The argument is a pointer to a structure
+.in +4n
+.EX
+struct perf_event_query_bpf {
+    __u32    ids_len;
+    __u32    prog_cnt;
+    __u32    ids[0];
+};
+.EE
+.in
+.IP
+The
+.I ids_len
+field indicates the number of ids that can fit in the provided
+.I ids
+array.
+The
+.I prog_cnt
+value is filled in by the kernel with the number of attached
+BPF programs.
+The
+.I ids
+array is filled with the ID of each attached BPF program.
+If there are more programs than will fit in the array, then the
+kernel will return
+.B ENOSPC
+and
+.I ids_len
+will indicate the number of program IDs that were successfully copied.
+.\"
+.SS Using prctl(2)
+A process can enable or disable all currently open event groups
+using the
+.BR prctl (2)
+.B PR_TASK_PERF_EVENTS_ENABLE
+and
+.B PR_TASK_PERF_EVENTS_DISABLE
+operations.
+This applies only to events created locally by the calling process.
+This does not apply to events created by other processes attached
+to the calling process or inherited events from a parent process.
+Only group leaders are enabled and disabled,
+not any other members of the groups.
+.SS perf_event related configuration files
+Files in
+.I /proc/sys/kernel/
+.RS 4
+.TP
+.I /proc/sys/kernel/perf_event_paranoid
+The
+.I perf_event_paranoid
+file can be set to restrict access to the performance counters.
+.IP
+.PD 0
+.RS
+.TP
+.B 2
+allow only user-space measurements (default since Linux 4.6).
+.\" default changed in commit 0161028b7c8aebef64194d3d73e43bc3b53b5c66
+.TP
+.B 1
+allow both kernel and user measurements (default before Linux 4.6).
+.TP
+.B 0
+allow access to CPU-specific data but not raw tracepoint samples.
+.TP
+.B \-1
+no restrictions.
+.RE
+.PD
+.IP
+The existence of the
+.I perf_event_paranoid
+file is the official method for determining if a kernel supports
+.BR perf_event_open ().
+.TP
+.I /proc/sys/kernel/perf_event_max_sample_rate
+This sets the maximum sample rate.
+Setting this too high can allow
+users to sample at a rate that impacts overall machine performance
+and potentially lock up the machine.
+The default value is
+100000 (samples per second).
+.TP
+.I /proc/sys/kernel/perf_event_max_stack
+.\" Introduced in c5dfd78eb79851e278b7973031b9ca363da87a7e
+This file sets the maximum depth of stack frame entries reported
+when generating a call trace.
+.TP
+.I /proc/sys/kernel/perf_event_mlock_kb
+Maximum number of pages an unprivileged user can
+.BR mlock (2).
+The default is 516 (kB).
+.RE
+.P
+Files in
+.I /sys/bus/event_source/devices/
+.P
+.RS 4
+Since Linux 2.6.34, the kernel supports having multiple PMUs
+available for monitoring.
+Information on how to program these PMUs can be found under
+.IR /sys/bus/event_source/devices/ .
+Each subdirectory corresponds to a different PMU.
+.TP
+.IR /sys/bus/event_source/devices/*/type " (since Linux 2.6.38)"
+.\" commit abe43400579d5de0078c2d3a760e6598e183f871
+This contains an integer that can be used in the
+.I type
+field of
+.I perf_event_attr
+to indicate that you wish to use this PMU.
+.TP
+.IR /sys/bus/event_source/devices/cpu/rdpmc " (since Linux 3.4)"
+.\" commit 0c9d42ed4cee2aa1dfc3a260b741baae8615744f
+If this file is 1, then direct user-space access to the
+performance counter registers is allowed via the rdpmc instruction.
+This can be disabled by echoing 0 to the file.
+.IP
+As of Linux 4.0
+.\" a66734297f78707ce39d756b656bfae861d53f62
+.\" 7911d3f7af14a614617e38245fedf98a724e46a9
+the behavior has changed, so that 1 now means only allow access
+to processes with active perf events, with 2 indicating the old
+allow-anyone-access behavior.
+.TP
+.IR /sys/bus/event_source/devices/*/format/ " (since Linux 3.4)"
+.\" commit 641cc938815dfd09f8fa1ec72deb814f0938ac33
+This subdirectory contains information on the architecture-specific
+subfields available for programming the various
+.I config
+fields in the
+.I perf_event_attr
+struct.
+.IP
+The content of each file is the name of the config field, followed
+by a colon, followed by a series of integer bit ranges separated by
+commas.
+For example, the file
+.I event
+may contain the value
+.I config1:1,6\-10,44
+which indicates that event is an attribute that occupies bits 1,6\[en]10, and 44
+of
+.IR perf_event_attr::config1 .
+.TP
+.IR /sys/bus/event_source/devices/*/events/ " (since Linux 3.4)"
+.\" commit 641cc938815dfd09f8fa1ec72deb814f0938ac33
+This subdirectory contains files with predefined events.
+The contents are strings describing the event settings
+expressed in terms of the fields found in the previously mentioned
+.I ./format/
+directory.
+These are not necessarily complete lists of all events supported by
+a PMU, but usually a subset of events deemed useful or interesting.
+.IP
+The content of each file is a list of attribute names
+separated by commas.
+Each entry has an optional value (either hex or decimal).
+If no value is specified, then it is assumed to be a single-bit
+field with a value of 1.
+An example entry may look like this:
+.IR event=0x2,inv,ldlat=3 .
+.TP
+.I /sys/bus/event_source/devices/*/uevent
+This file is the standard kernel device interface
+for injecting hotplug events.
+.TP
+.IR /sys/bus/event_source/devices/*/cpumask " (since Linux 3.7)"
+.\" commit 314d9f63f385096580e9e2a06eaa0745d92fe4ac
+The
+.I cpumask
+file contains a comma-separated list of integers that
+indicate a representative CPU number for each socket (package)
+on the motherboard.
+This is needed when setting up uncore or northbridge events, as
+those PMUs present socket-wide events.
+.RE
+.SH RETURN VALUE
+On success,
+.BR perf_event_open ()
+returns the new file descriptor.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The errors returned by
+.BR perf_event_open ()
+can be inconsistent, and may
+vary across processor architectures and performance monitoring units.
+.TP
+.B E2BIG
+Returned if the
+.I perf_event_attr
+.I size
+value is too small
+(smaller than
+.BR PERF_ATTR_SIZE_VER0 ),
+too big (larger than the page size),
+or larger than the kernel supports and the extra bytes are not zero.
+When
+.B E2BIG
+is returned, the
+.I perf_event_attr
+.I size
+field is overwritten by the kernel to be the size of the structure
+it was expecting.
+.TP
+.B EACCES
+Returned when the requested event requires
+.B CAP_PERFMON
+(since Linux 5.8) or
+.B CAP_SYS_ADMIN
+permissions (or a more permissive perf_event paranoid setting).
+Some common cases where an unprivileged process
+may encounter this error:
+attaching to a process owned by a different user;
+monitoring all processes on a given CPU (i.e., specifying the
+.I pid
+argument as \-1);
+and not setting
+.I exclude_kernel
+when the paranoid setting requires it.
+.TP
+.B EBADF
+Returned if the
+.I group_fd
+file descriptor is not valid, or, if
+.B PERF_FLAG_PID_CGROUP
+is set,
+the cgroup file descriptor in
+.I pid
+is not valid.
+.TP
+.BR EBUSY " (since Linux 4.1)"
+.\" bed5b25ad9c8a2f5d735ef0bc746ec870c01c1b0
+Returned if another event already has exclusive
+access to the PMU.
+.TP
+.B EFAULT
+Returned if the
+.I attr
+pointer points at an invalid memory address.
+.TP
+.B EINTR
+Returned when trying to mix perf and ftrace handling
+for a uprobe.
+.TP
+.B EINVAL
+Returned if the specified event is invalid.
+There are many possible reasons for this.
+A not-exhaustive list:
+.I sample_freq
+is higher than the maximum setting;
+the
+.I cpu
+to monitor does not exist;
+.I read_format
+is out of range;
+.I sample_type
+is out of range;
+the
+.I flags
+value is out of range;
+.I exclusive
+or
+.I pinned
+set and the event is not a group leader;
+the event
+.I config
+values are out of range or set reserved bits;
+the generic event selected is not supported; or
+there is not enough room to add the selected event.
+.TP
+.B EMFILE
+Each opened event uses one file descriptor.
+If a large number of events are opened,
+the per-process limit on the number of open file descriptors will be reached,
+and no more events can be created.
+.TP
+.B ENODEV
+Returned when the event involves a feature not supported
+by the current CPU.
+.TP
+.B ENOENT
+Returned if the
+.I type
+setting is not valid.
+This error is also returned for
+some unsupported generic events.
+.TP
+.B ENOSPC
+Prior to Linux 3.3, if there was not enough room for the event,
+.\" commit aa2bc1ade59003a379ffc485d6da2d92ea3370a6
+.B ENOSPC
+was returned.
+In Linux 3.3, this was changed to
+.BR EINVAL .
+.B ENOSPC
+is still returned if you try to add more breakpoint events
+than supported by the hardware.
+.TP
+.B ENOSYS
+Returned if
+.B PERF_SAMPLE_STACK_USER
+is set in
+.I sample_type
+and it is not supported by hardware.
+.TP
+.B EOPNOTSUPP
+Returned if an event requiring a specific hardware feature is
+requested but there is no hardware support.
+This includes requesting low-skid events if not supported,
+branch tracing if it is not available, sampling if no PMU
+interrupt is available, and branch stacks for software events.
+.TP
+.BR EOVERFLOW " (since Linux 4.8)"
+.\" 97c79a38cd454602645f0470ffb444b3b75ce574
+Returned if
+.B PERF_SAMPLE_CALLCHAIN
+is requested and
+.I sample_max_stack
+is larger than the maximum specified in
+.IR /proc/sys/kernel/perf_event_max_stack .
+.TP
+.B EPERM
+Returned on many (but not all) architectures when an unsupported
+.IR exclude_hv ", " exclude_idle ", " exclude_user ", or " exclude_kernel
+setting is specified.
+.IP
+It can also happen, as with
+.BR EACCES ,
+when the requested event requires
+.B CAP_PERFMON
+(since Linux 5.8) or
+.B CAP_SYS_ADMIN
+permissions (or a more permissive perf_event paranoid setting).
+This includes setting a breakpoint on a kernel address,
+and (since Linux 3.13) setting a kernel function-trace tracepoint.
+.\" commit a4e95fc2cbb31d70a65beffeaf8773f881328c34
+.TP
+.B ESRCH
+Returned if attempting to attach to a process that does not exist.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.BR perf_event_open ()
+was introduced in Linux 2.6.31 but was called
+.\" commit 0793a61d4df8daeac6492dbf8d2f3e5713caae5e
+.BR perf_counter_open ().
+It was renamed in Linux 2.6.32.
+.\" commit cdd6c482c9ff9c55475ee7392ec8f672eddb7be6
+.SH NOTES
+The official way of knowing if
+.BR perf_event_open ()
+support is enabled is checking
+for the existence of the file
+.IR /proc/sys/kernel/perf_event_paranoid .
+.P
+.B CAP_PERFMON
+capability (since Linux 5.8) provides secure approach to
+performance monitoring and observability operations in a system
+according to the principal of least privilege (POSIX IEEE 1003.1e).
+Accessing system performance monitoring and observability operations
+using
+.B CAP_PERFMON
+rather than the much more powerful
+.B CAP_SYS_ADMIN
+excludes chances to misuse credentials and makes operations more secure.
+.B CAP_SYS_ADMIN
+usage for secure system performance monitoring and observability
+is discouraged in favor of the
+.B CAP_PERFMON
+capability.
+.SH BUGS
+The
+.B F_SETOWN_EX
+option to
+.BR fcntl (2)
+is needed to properly get overflow signals in threads.
+This was introduced in Linux 2.6.32.
+.\" commit ba0a6c9f6fceed11c6a99e8326f0477fe383e6b5
+.P
+Prior to Linux 2.6.33 (at least for x86),
+.\" commit b690081d4d3f6a23541493f1682835c3cd5c54a1
+the kernel did not check
+if events could be scheduled together until read time.
+The same happens on all known kernels if the NMI watchdog is enabled.
+This means to see if a given set of events works you have to
+.BR perf_event_open (),
+start, then read before you know for sure you
+can get valid measurements.
+.P
+Prior to Linux 2.6.34,
+.\" FIXME . cannot find a kernel commit for this one
+event constraints were not enforced by the kernel.
+In that case, some events would silently return "0" if the kernel
+scheduled them in an improper counter slot.
+.P
+Prior to Linux 2.6.34, there was a bug when multiplexing where the
+wrong results could be returned.
+.\" commit 45e16a6834b6af098702e5ea6c9a40de42ff77d8
+.P
+Kernels from Linux 2.6.35 to Linux 2.6.39 can quickly crash the kernel if
+"inherit" is enabled and many threads are started.
+.\" commit 38b435b16c36b0d863efcf3f07b34a6fac9873fd
+.P
+Prior to Linux 2.6.35,
+.\" commit 050735b08ca8a016bbace4445fa025b88fee770b
+.B PERF_FORMAT_GROUP
+did not work with attached processes.
+.P
+There is a bug in the kernel code between
+Linux 2.6.36 and Linux 3.0 that ignores the
+"watermark" field and acts as if a wakeup_event
+was chosen if the union has a
+nonzero value in it.
+.\" commit 4ec8363dfc1451f8c8f86825731fe712798ada02
+.P
+From Linux 2.6.31 to Linux 3.4, the
+.B PERF_IOC_FLAG_GROUP
+ioctl argument was broken and would repeatedly operate
+on the event specified rather than iterating across
+all sibling events in a group.
+.\" commit 724b6daa13e100067c30cfc4d1ad06629609dc4e
+.P
+From Linux 3.4 to Linux 3.11, the mmap
+.\" commit fa7315871046b9a4c48627905691dbde57e51033
+.I cap_usr_rdpmc
+and
+.I cap_usr_time
+bits mapped to the same location.
+Code should migrate to the new
+.I cap_user_rdpmc
+and
+.I cap_user_time
+fields instead.
+.P
+Always double-check your results!
+Various generalized events have had wrong values.
+For example, retired branches measured
+the wrong thing on AMD machines until Linux 2.6.35.
+.\" commit f287d332ce835f77a4f5077d2c0ef1e3f9ea42d2
+.SH EXAMPLES
+The following is a short example that measures the total
+instruction count of a call to
+.BR printf (3).
+.P
+.\" SRC BEGIN (perf_event_open.c)
+.EX
+#include <linux/perf_event.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+static long
+perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
+                int cpu, int group_fd, unsigned long flags)
+{
+    int ret;
+\&
+    ret = syscall(SYS_perf_event_open, hw_event, pid, cpu,
+                  group_fd, flags);
+    return ret;
+}
+\&
+int
+main(void)
+{
+    int                     fd;
+    long long               count;
+    struct perf_event_attr  pe;
+\&
+    memset(&pe, 0, sizeof(pe));
+    pe.type = PERF_TYPE_HARDWARE;
+    pe.size = sizeof(pe);
+    pe.config = PERF_COUNT_HW_INSTRUCTIONS;
+    pe.disabled = 1;
+    pe.exclude_kernel = 1;
+    pe.exclude_hv = 1;
+\&
+    fd = perf_event_open(&pe, 0, \-1, \-1, 0);
+    if (fd == \-1) {
+       fprintf(stderr, "Error opening leader %llx\en", pe.config);
+       exit(EXIT_FAILURE);
+    }
+\&
+    ioctl(fd, PERF_EVENT_IOC_RESET, 0);
+    ioctl(fd, PERF_EVENT_IOC_ENABLE, 0);
+\&
+    printf("Measuring instruction count for this printf\en");
+\&
+    ioctl(fd, PERF_EVENT_IOC_DISABLE, 0);
+    read(fd, &count, sizeof(count));
+\&
+    printf("Used %lld instructions\en", count);
+\&
+    close(fd);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR perf (1),
+.BR fcntl (2),
+.BR mmap (2),
+.BR open (2),
+.BR prctl (2),
+.BR read (2)
+.P
+.I Documentation/admin\-guide/perf\-security.rst
+in the kernel source tree
diff --git a/man/man2/perfmonctl.2 b/man/man2/perfmonctl.2
new file mode 100644
index 000000000..d4bf56b9a
--- /dev/null
+++ b/man/man2/perfmonctl.2
@@ -0,0 +1,193 @@
+.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+.\" and Copyright (C) 2013 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Written by Ivana Varekova <varekova@redhat.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH perfmonctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+perfmonctl \- interface to IA-64 performance monitoring unit
+.SH SYNOPSIS
+.nf
+.B #include <syscall.h>
+.B #include <perfmon.h>
+.P
+.BI "long perfmonctl(int " fd ", int " cmd ", void " arg [. narg "], int " narg ");"
+.fi
+.P
+.IR Note :
+There is no glibc wrapper for this system call; see HISTORY.
+.SH DESCRIPTION
+The IA-64-specific
+.BR perfmonctl ()
+system call provides an interface to the
+PMU (performance monitoring unit).
+The PMU consists of PMD (performance monitoring data) registers and
+PMC (performance monitoring control) registers,
+which gather hardware statistics.
+.P
+.BR perfmonctl ()
+applies the operation
+.I cmd
+to the input arguments specified by
+.IR arg .
+The number of arguments is defined by \fInarg\fR.
+The
+.I fd
+argument specifies the perfmon context to operate on.
+.P
+Supported values for
+.I cmd
+are:
+.TP
+.B PFM_CREATE_CONTEXT
+.nf
+.BI  "perfmonctl(int " fd ", PFM_CREATE_CONTEXT, pfarg_context_t *" ctxt ", 1);"
+.fi
+Set up a context.
+.IP
+The
+.I fd
+parameter is ignored.
+A new perfmon context is created as specified in
+.I ctxt
+and its file descriptor is returned in \fIctxt\->ctx_fd\fR.
+.IP
+The file descriptor can be used in subsequent calls to
+.BR perfmonctl ()
+and can be used to read event notifications (type
+.IR pfm_msg_t )
+using
+.BR read (2).
+The file descriptor is pollable using
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7).
+.IP
+The context can be destroyed by calling
+.BR close (2)
+on the file descriptor.
+.TP
+.B PFM_WRITE_PMCS
+.\" pfm_write_pmcs()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_WRITE_PMCS, pfarg_reg_t *" pmcs ", n);"
+.fi
+Set PMC registers.
+.TP
+.B PFM_WRITE_PMDS
+.nf
+.BI  "perfmonctl(int " fd ", PFM_WRITE_PMDS, pfarg_reg_t *" pmds ", n);"
+.fi
+.\" pfm_write_pmds()
+Set PMD registers.
+.TP
+.B PFM_READ_PMDS
+.\" pfm_read_pmds()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_READ_PMDS, pfarg_reg_t *" pmds ", n);"
+.fi
+Read PMD registers.
+.TP
+.B PFM_START
+.\" pfm_start()
+.nf
+.\" .BI  "perfmonctl(int " fd ", PFM_START, arg, 1);
+.BI  "perfmonctl(int " fd ", PFM_START, NULL, 0);"
+.fi
+Start monitoring.
+.TP
+.B PFM_STOP
+.\" pfm_stop()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_STOP, NULL, 0);"
+.fi
+Stop monitoring.
+.TP
+.B PFM_LOAD_CONTEXT
+.\" pfm_context_load()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_LOAD_CONTEXT, pfarg_load_t *" largs ", 1);"
+.fi
+Attach the context to a thread.
+.TP
+.B PFM_UNLOAD_CONTEXT
+.\" pfm_context_unload()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_UNLOAD_CONTEXT, NULL, 0);"
+.fi
+Detach the context from a thread.
+.TP
+.B PFM_RESTART
+.\" pfm_restart()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_RESTART, NULL, 0);"
+.fi
+Restart monitoring after receiving an overflow notification.
+.TP
+.B PFM_GET_FEATURES
+.\" pfm_get_features()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_GET_FEATURES, pfarg_features_t *" arg ", 1);"
+.fi
+.TP
+.B PFM_DEBUG
+.\" pfm_debug()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_DEBUG, " val ", 0);"
+.fi
+If
+.I val
+is nonzero, enable debugging mode, otherwise disable.
+.TP
+.B PFM_GET_PMC_RESET_VAL
+.\" pfm_get_pmc_reset()
+.nf
+.BI  "perfmonctl(int " fd ", PFM_GET_PMC_RESET_VAL, pfarg_reg_t *" req  ", n);"
+.fi
+Reset PMC registers to default values.
+.\"
+.\"
+.\" .TP
+.\" .B PFM_CREATE_EVTSETS
+.\"
+.\" create or modify event sets
+.\" .nf
+.\" .BI  "perfmonctl(int " fd ", PFM_CREATE_EVTSETS, pfarg_setdesc_t *desc , n);
+.\" .fi
+.\" .TP
+.\" .B PFM_DELETE_EVTSETS
+.\" delete event sets
+.\" .nf
+.\" .BI  "perfmonctl(int " fd ", PFM_DELETE_EVTSET, pfarg_setdesc_t *desc , n);
+.\" .fi
+.\" .TP
+.\" .B PFM_GETINFO_EVTSETS
+.\" get information about event sets
+.\" .nf
+.\" .BI  "perfmonctl(int " fd ", PFM_GETINFO_EVTSETS, pfarg_setinfo_t *info, n);
+.\" .fi
+.SH RETURN VALUE
+.BR perfmonctl ()
+returns zero when the operation is successful.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH STANDARDS
+Linux on IA-64.
+.SH HISTORY
+Added in Linux 2.4;
+.\" commit ecf5b72d5f66af843f189dfe9ce31598c3e48ad7
+removed in Linux 5.10.
+.P
+This system call was broken for many years,
+and ultimately removed in Linux 5.10.
+.P
+glibc does not provide a wrapper for this system call;
+on kernels where it exists, call it using
+.BR syscall (2).
+.SH SEE ALSO
+.BR gprof (1)
+.P
+The perfmon2 interface specification
diff --git a/man/man2/personality.2 b/man/man2/personality.2
new file mode 100644
index 000000000..976f27c6d
--- /dev/null
+++ b/man/man2/personality.2
@@ -0,0 +1,296 @@
+.\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\" and Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created   Sat Aug 21 1995     Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\"
+.\" typo corrected, aeb, 950825
+.\" added layout change from joey, 960722
+.\" changed prototype, documented 0xffffffff, aeb, 030101
+.\" Modified 2004-11-03 patch from Martin Schulze <joey@infodrom.org>
+.\"
+.TH personality 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+personality \- set the process execution domain
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/personality.h>
+.P
+.BI "int personality(unsigned long " persona );
+.fi
+.SH DESCRIPTION
+Linux supports different execution domains, or personalities, for each
+process.
+Among other things, execution domains tell Linux how to map
+signal numbers into signal actions.
+The execution domain system allows
+Linux to provide limited support for binaries compiled under other
+UNIX-like operating systems.
+.P
+If
+.I persona
+is not
+0xffffffff, then
+.BR personality ()
+sets the caller's execution domain to the value specified by
+.IR persona .
+Specifying
+.I persona
+as 0xffffffff provides a way of retrieving
+the current persona without changing it.
+.P
+A list of the available execution domains can be found in
+.IR <sys/personality.h> .
+The execution domain is a 32-bit value in which the top three
+bytes are set aside for flags that cause the kernel to modify the
+behavior of certain system calls so as to emulate historical or
+architectural quirks.
+The least significant byte is a value defining the personality
+the kernel should assume.
+The flag values are as follows:
+.TP
+.BR ADDR_COMPAT_LAYOUT " (since Linux 2.6.9)"
+With this flag set, provide legacy virtual address space layout.
+.TP
+.BR ADDR_NO_RANDOMIZE " (since Linux 2.6.12)"
+With this flag set, disable address-space-layout randomization.
+.TP
+.BR ADDR_LIMIT_32BIT " (since Linux 2.2)"
+Limit the address space to 32 bits.
+.TP
+.BR ADDR_LIMIT_3GB " (since Linux 2.4.0)"
+With this flag set, use 0xc0000000 as the offset at which to search
+a virtual memory chunk on
+.BR mmap (2);
+otherwise use 0xffffe000.
+Applies to 32-bit x86 processes only.
+.TP
+.BR FDPIC_FUNCPTRS " (since Linux 2.6.11)"
+User-space function pointers to signal handlers point
+to descriptors.
+Applies only to ARM if BINFMT_ELF_FDPIC and SuperH.
+.TP
+.BR MMAP_PAGE_ZERO " (since Linux 2.4.0)"
+Map page 0 as read-only
+(to support binaries that depend on this SVr4 behavior).
+.TP
+.BR READ_IMPLIES_EXEC " (since Linux 2.6.8)"
+With this flag set,
+.B PROT_READ
+implies
+.B PROT_EXEC
+for
+.BR mmap (2).
+.TP
+.BR SHORT_INODE " (since Linux 2.4.0)"
+No effect.
+.TP
+.BR STICKY_TIMEOUTS " (since Linux 1.2.0)"
+With this flag set,
+.BR select (2),
+.BR pselect (2),
+and
+.BR ppoll (2)
+do not modify the returned timeout argument when
+interrupted by a signal handler.
+.TP
+.BR UNAME26 " (since Linux 3.1)"
+Have
+.BR uname (2)
+report a 2.6.(40+x) version number rather than a MAJOR.x version number.
+Added as a stopgap measure to support broken applications that
+could not handle the
+kernel version-numbering switch from Linux 2.6.x to Linux 3.x.
+.TP
+.BR WHOLE_SECONDS " (since Linux 1.2.0)"
+No effect.
+.P
+The available execution domains are:
+.TP
+.BR PER_BSD " (since Linux 1.2.0)"
+BSD. (No effects.)
+.TP
+.BR PER_HPUX " (since Linux 2.4)"
+Support for 32-bit HP/UX.
+This support was never complete, and was dropped so that since Linux 4.0,
+this value has no effect.
+.TP
+.BR PER_IRIX32 " (since Linux 2.2)"
+IRIX 5 32-bit.
+Never fully functional; support dropped in Linux 2.6.27.
+Implies
+.BR STICKY_TIMEOUTS .
+.TP
+.BR PER_IRIX64 " (since Linux 2.2)"
+IRIX 6 64-bit.
+Implies
+.BR STICKY_TIMEOUTS ;
+otherwise no effect.
+.TP
+.BR PER_IRIXN32 " (since Linux 2.2)"
+IRIX 6 new 32-bit.
+Implies
+.BR STICKY_TIMEOUTS ;
+otherwise no effect.
+.TP
+.BR PER_ISCR4 " (since Linux 1.2.0)"
+Implies
+.BR STICKY_TIMEOUTS ;
+otherwise no effect.
+.TP
+.BR PER_LINUX " (since Linux 1.2.0)"
+Linux.
+.TP
+.BR PER_LINUX32 " (since Linux 2.2)"
+.BR uname (2)
+returns the name of the 32-bit architecture in the
+.I machine
+field ("i686" instead of "x86_64", &c.).
+.IP
+Under ia64 (Itanium), processes with this personality don't have the
+O_LARGEFILE
+.BR open (2)
+flag forced.
+.IP
+Under 64-bit ARM, setting this personality is forbidden if
+.BR execve (2)ing
+a 32-bit process would also be forbidden
+(cf. the allow_mismatched_32bit_el0 kernel parameter and
+.IR Documentation/arm64/asymmetric-32bit.rst ).
+.TP
+.BR PER_LINUX32_3GB " (since Linux 2.4)"
+Same as
+.BR PER_LINUX32 ,
+but implies
+.BR ADDR_LIMIT_3GB .
+.TP
+.BR PER_LINUX_32BIT " (since Linux 2.0)"
+Same as
+.BR PER_LINUX ,
+but implies
+.BR ADDR_LIMIT_32BIT .
+.TP
+.BR PER_LINUX_FDPIC " (since Linux 2.6.11)"
+Same as
+.BR PER_LINUX ,
+but implies
+.BR FDPIC_FUNCPTRS .
+.TP
+.BR PER_OSF4 " (since Linux 2.4)"
+OSF/1 v4.
+.\" commit 987f20a9dcce3989e48d87cff3952c095c994445
+No effect since Linux 6.1, which removed a.out binary support.
+Before, on alpha,
+.\" Following is from a comment in arch/alpha/kernel/osf_sys.c
+would clear top 32 bits of iov_len in the user's buffer for
+compatibility with old versions of OSF/1 where iov_len
+was defined as.
+.IR int .
+.TP
+.BR PER_OSR5 " (since Linux 2.4)"
+SCO OpenServer 5.
+Implies
+.B STICKY_TIMEOUTS
+and
+.BR WHOLE_SECONDS ;
+otherwise no effect.
+.TP
+.BR PER_RISCOS " (since Linux 2.3.7; macro since Linux 2.3.13)"
+Acorn RISC OS/Arthur (MIPS).
+No effect.
+.\" commit 125ec7b4e90cbae4eed5a7ff1ee479cc331dcf3c
+Up to Linux v4.0, would set the emulation altroot to
+.I /usr/gnemul/riscos
+(cf.\&
+.BR PER_SUNOS ,
+below).
+Before then, up to Linux 2.6.3, just Arthur emulation.
+.TP
+.BR PER_SCOSVR3 " (since Linux 1.2.0)"
+SCO UNIX System V Release 3.
+Same as
+.BR PER_OSR5 ,
+but also implies
+.BR SHORT_INODE .
+.TP
+.BR PER_SOLARIS " (since Linux 2.4)"
+Solaris.
+Implies
+.BR STICKY_TIMEOUTS ;
+otherwise no effect.
+.TP
+.BR PER_SUNOS " (since Linux 2.4.0)"
+Sun OS.
+Same as
+.BR PER_BSD ,
+but implies
+.BR STICKY_TIMEOUTS .
+Prior to Linux 2.6.26,
+diverted library and dynamic linker searches to
+.IR /usr/gnemul .
+Buggy, largely unmaintained, and almost entirely unused.
+.TP
+.BR PER_SVR3 " (since Linux 1.2.0)"
+AT&T UNIX System V Release 3.
+Implies
+.B STICKY_TIMEOUTS
+and
+.BR SHORT_INODE ;
+otherwise no effect.
+.TP
+.BR PER_SVR4 " (since Linux 1.2.0)"
+AT&T UNIX System V Release 4.
+Implies
+.B STICKY_TIMEOUTS
+and
+.BR MMAP_PAGE_ZERO ;
+otherwise no effect.
+.TP
+.BR PER_UW7 " (since Linux 2.4)"
+UnixWare 7.
+Implies
+.B STICKY_TIMEOUTS
+and
+.BR MMAP_PAGE_ZERO ;
+otherwise no effect.
+.TP
+.BR PER_WYSEV386 " (since Linux 1.2.0)"
+WYSE UNIX System V/386.
+Implies
+.B STICKY_TIMEOUTS
+and
+.BR SHORT_INODE ;
+otherwise no effect.
+.TP
+.BR PER_XENIX " (since Linux 1.2.0)"
+XENIX.
+Implies
+.B STICKY_TIMEOUTS
+and
+.BR SHORT_INODE ;
+otherwise no effect.
+.SH RETURN VALUE
+On success, the previous
+.I persona
+is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The kernel was unable to change the personality.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 1.1.20,
+.\" (and thus first in a stable kernel release with Linux 1.2.0)
+glibc 2.3.
+.\" personality wrapper first appeared in glibc 1.90,
+.\" <sys/personality.h> was added later in glibc 2.2.91.
+.SH SEE ALSO
+.BR setarch (8)
diff --git a/man/man2/phys.2 b/man/man2/phys.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/phys.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/pidfd_getfd.2 b/man/man2/pidfd_getfd.2
new file mode 100644
index 000000000..ba92823cb
--- /dev/null
+++ b/man/man2/pidfd_getfd.2
@@ -0,0 +1,144 @@
+.\" Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pidfd_getfd 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pidfd_getfd \- obtain a duplicate of another process's file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_pidfd_getfd, int " pidfd ", int " targetfd ,
+.BI "            unsigned int " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR pidfd_getfd (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR pidfd_getfd ()
+system call allocates a new file descriptor in the calling process.
+This new file descriptor is a duplicate of an existing file descriptor,
+.IR targetfd ,
+in the process referred to by the PID file descriptor
+.IR pidfd .
+.P
+The duplicate file descriptor refers to the same open file description (see
+.BR open (2))
+as the original file descriptor in the process referred to by
+.IR pidfd .
+The two file descriptors thus share file status flags and file offset.
+Furthermore, operations on the underlying file object
+(for example, assigning an address to a socket object using
+.BR bind (2))
+can equally be performed via the duplicate file descriptor.
+.P
+The close-on-exec flag
+.RB ( FD_CLOEXEC ;
+see
+.BR fcntl (2))
+is set on the file descriptor returned by
+.BR pidfd_getfd ().
+.P
+The
+.I flags
+argument is reserved for future use.
+Currently, it must be specified as 0.
+.P
+Permission to duplicate another process's file descriptor
+is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_REALCREDS
+check (see
+.BR ptrace (2)).
+.SH RETURN VALUE
+On success,
+.BR pidfd_getfd ()
+returns a file descriptor (a nonnegative integer).
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I pidfd
+is not a valid PID file descriptor.
+.TP
+.B EBADF
+.I targetfd
+is not an open file descriptor in the process referred to by
+.IR pidfd .
+.TP
+.B EINVAL
+.I flags
+is not 0.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached
+(see the description of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2)).
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B EPERM
+The calling process did not have
+.B PTRACE_MODE_ATTACH_REALCREDS
+permissions (see
+.BR ptrace (2))
+over the process referred to by
+.IR pidfd .
+.TP
+.B ESRCH
+The process referred to by
+.I pidfd
+does not exist
+(i.e., it has terminated and been waited on).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.6.
+.\" commit 8649c322f75c96e7ced2fec201e123b2b073bf09
+.SH NOTES
+For a description of PID file descriptors, see
+.BR pidfd_open (2).
+.P
+The effect of
+.BR pidfd_getfd ()
+is similar to the use of
+.B SCM_RIGHTS
+messages described in
+.BR unix (7),
+but differs in the following respects:
+.IP \[bu] 3
+In order to pass a file descriptor using an
+.B SCM_RIGHTS
+message,
+the two processes must first establish a UNIX domain socket connection.
+.IP \[bu]
+The use of
+.B SCM_RIGHTS
+requires cooperation on the part of the process whose
+file descriptor is being copied.
+By contrast, no such cooperation is necessary when using
+.BR pidfd_getfd ().
+.IP \[bu]
+The ability to use
+.BR pidfd_getfd ()
+is restricted by a
+.B PTRACE_MODE_ATTACH_REALCREDS
+ptrace  access  mode check.
+.SH SEE ALSO
+.BR clone3 (2),
+.BR dup (2),
+.BR kcmp (2),
+.BR pidfd_open (2)
diff --git a/man/man2/pidfd_open.2 b/man/man2/pidfd_open.2
new file mode 100644
index 000000000..02c741f2b
--- /dev/null
+++ b/man/man2/pidfd_open.2
@@ -0,0 +1,269 @@
+.\" Copyright (c) 2019 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pidfd_open 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pidfd_open \- obtain a file descriptor that refers to a process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_pidfd_open, pid_t " pid ", unsigned int " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR pidfd_open (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR pidfd_open ()
+system call creates a file descriptor that refers to
+the process whose PID is specified in
+.IR pid .
+The file descriptor is returned as the function result;
+the close-on-exec flag is set on the file descriptor.
+.P
+The
+.I flags
+argument either has the value 0, or contains the following flag:
+.TP
+.BR PIDFD_NONBLOCK " (since Linux 5.10)"
+.\" commit 4da9af0014b51c8b015ed8c622440ef28912efe6
+Return a nonblocking file descriptor.
+If the process referred to by the file descriptor has not yet terminated,
+then an attempt to wait on the file descriptor using
+.BR waitid (2)
+will immediately return the error
+.B EAGAIN
+rather than blocking.
+.SH RETURN VALUE
+On success,
+.BR pidfd_open ()
+returns a file descriptor (a nonnegative integer).
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I flags
+is not valid.
+.TP
+.B EINVAL
+.I pid
+is not valid.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached
+(see the description of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2)).
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENODEV
+The anonymous inode filesystem is not available in this kernel.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ESRCH
+The process specified by
+.I pid
+does not exist.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.3.
+.SH NOTES
+The following code sequence can be used to obtain a file descriptor
+for the child of
+.BR fork (2):
+.P
+.in +4n
+.EX
+pid = fork();
+if (pid > 0) {     /* If parent */
+    pidfd = pidfd_open(pid, 0);
+    ...
+}
+.EE
+.in
+.P
+Even if the child has already terminated by the time of the
+.BR pidfd_open ()
+call, its PID will not have been recycled and the returned
+file descriptor will refer to the resulting zombie process.
+Note, however, that this is guaranteed only if the following
+conditions hold true:
+.IP \[bu] 3
+the disposition of
+.B SIGCHLD
+has not been explicitly set to
+.B SIG_IGN
+(see
+.BR sigaction (2));
+.IP \[bu]
+the
+.B SA_NOCLDWAIT
+flag was not specified while establishing a handler for
+.B SIGCHLD
+or while setting the disposition of that signal to
+.B SIG_DFL
+(see
+.BR sigaction (2));
+and
+.IP \[bu]
+the zombie process was not reaped elsewhere in the program
+(e.g., either by an asynchronously executed signal handler or by
+.BR wait (2)
+or similar in another thread).
+.P
+If any of these conditions does not hold,
+then the child process (along with a PID file descriptor that refers to it)
+should instead be created using
+.BR clone (2)
+with the
+.B CLONE_PIDFD
+flag.
+.\"
+.SS Use cases for PID file descriptors
+A PID file descriptor returned by
+.BR pidfd_open ()
+(or by
+.BR clone (2)
+with the
+.B CLONE_PID
+flag) can be used for the following purposes:
+.IP \[bu] 3
+The
+.BR pidfd_send_signal (2)
+system call can be used to send a signal to the process referred to by
+a PID file descriptor.
+.IP \[bu]
+A PID file descriptor can be monitored using
+.BR poll (2),
+.BR select (2),
+and
+.BR epoll (7).
+When the process that it refers to terminates,
+these interfaces indicate the file descriptor as readable.
+Note, however, that in the current implementation,
+nothing can be read from the file descriptor
+.RB ( read (2)
+on the file descriptor fails with the error
+.BR EINVAL ).
+.IP \[bu]
+If the PID file descriptor refers to a child of the calling process,
+then it can be waited on using
+.BR waitid (2).
+.IP \[bu]
+The
+.BR pidfd_getfd (2)
+system call can be used to obtain a duplicate of a file descriptor
+of another process referred to by a PID file descriptor.
+.IP \[bu]
+A PID file descriptor can be used as the argument of
+.BR setns (2)
+in order to move into one or more of the same namespaces as the process
+referred to by the file descriptor.
+.IP \[bu]
+A PID file descriptor can be used as the argument of
+.BR process_madvise (2)
+in order to provide advice on the memory usage patterns of the process
+referred to by the file descriptor.
+.P
+The
+.BR pidfd_open ()
+system call is the preferred way of obtaining a PID file descriptor
+for an already existing process.
+The alternative is to obtain a file descriptor by opening a
+.IR /proc/ pid
+directory.
+However, the latter technique is possible only if the
+.BR proc (5)
+filesystem is mounted;
+furthermore, the file descriptor obtained in this way is
+.I not
+pollable and can't be waited on with
+.BR waitid (2).
+.SH EXAMPLES
+The program below opens a PID file descriptor for the
+process whose PID is specified as its command-line argument.
+It then uses
+.BR poll (2)
+to monitor the file descriptor for process exit, as indicated by an
+.B EPOLLIN
+event.
+.\"
+.SS Program source
+\&
+.\" SRC BEGIN (pidfd_open.c)
+.EX
+#define _GNU_SOURCE
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+static int
+pidfd_open(pid_t pid, unsigned int flags)
+{
+    return syscall(SYS_pidfd_open, pid, flags);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int            pidfd, ready;
+    struct pollfd  pollfd;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <pid>\en", argv[0]);
+        exit(EXIT_SUCCESS);
+    }
+\&
+    pidfd = pidfd_open(atoi(argv[1]), 0);
+    if (pidfd == \-1) {
+        perror("pidfd_open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    pollfd.fd = pidfd;
+    pollfd.events = POLLIN;
+\&
+    ready = poll(&pollfd, 1, \-1);
+    if (ready == \-1) {
+        perror("poll");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Events (%#x): POLLIN is %sset\en", pollfd.revents,
+           (pollfd.revents & POLLIN) ? "" : "not ");
+\&
+    close(pidfd);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clone (2),
+.BR kill (2),
+.BR pidfd_getfd (2),
+.BR pidfd_send_signal (2),
+.BR poll (2),
+.BR process_madvise (2),
+.BR select (2),
+.BR setns (2),
+.BR waitid (2),
+.BR epoll (7)
diff --git a/man/man2/pidfd_send_signal.2 b/man/man2/pidfd_send_signal.2
new file mode 100644
index 000000000..205808425
--- /dev/null
+++ b/man/man2/pidfd_send_signal.2
@@ -0,0 +1,240 @@
+.\" Copyright (c) 2019 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pidfd_send_signal 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pidfd_send_signal \- send a signal to a process specified by a file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/signal.h>" "     /* Definition of " SIG* " constants */"
+.BR "#include <signal.h>" "           /* Definition of " SI_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_pidfd_send_signal, int " pidfd ", int " sig ,
+.BI "            siginfo_t *_Nullable " info ", unsigned int " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR pidfd_send_signal (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR pidfd_send_signal ()
+system call sends the signal
+.I sig
+to the target process referred to by
+.IR pidfd ,
+a PID file descriptor that refers to a process.
+.\" See the very detailed commit message for kernel commit
+.\" 3eb39f47934f9d5a3027fe00d906a45fe3a15fad
+.P
+If the
+.I info
+argument points to a
+.I siginfo_t
+buffer, that buffer should be populated as described in
+.BR rt_sigqueueinfo (2).
+.P
+If the
+.I info
+argument is a null pointer,
+this is equivalent to specifying a pointer to a
+.I siginfo_t
+buffer whose fields match the values that are
+implicitly supplied when a signal is sent using
+.BR kill (2):
+.P
+.PD 0
+.IP \[bu] 3
+.I si_signo
+is set to the signal number;
+.IP \[bu]
+.I si_errno
+is set to 0;
+.IP \[bu]
+.I si_code
+is set to
+.BR SI_USER ;
+.IP \[bu]
+.I si_pid
+is set to the caller's PID; and
+.IP \[bu]
+.I si_uid
+is set to the caller's real user ID.
+.PD
+.P
+The calling process must either be in the same PID namespace as the
+process referred to by
+.IR pidfd ,
+or be in an ancestor of that namespace.
+.P
+The
+.I flags
+argument is reserved for future use;
+currently, this argument must be specified as 0.
+.SH RETURN VALUE
+On success,
+.BR pidfd_send_signal ()
+returns 0.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I pidfd
+is not a valid PID file descriptor.
+.TP
+.B EINVAL
+.I sig
+is not a valid signal.
+.TP
+.B EINVAL
+The calling process is not in a PID namespace from which it can
+send a signal to the target process.
+.TP
+.B EINVAL
+.I flags
+is not 0.
+.TP
+.B EPERM
+The calling process does not have permission to send the signal
+to the target process.
+.TP
+.B EPERM
+.I pidfd
+doesn't refer to the calling process, and
+.I info.si_code
+is invalid (see
+.BR rt_sigqueueinfo (2)).
+.TP
+.B ESRCH
+The target process does not exist
+(i.e., it has terminated and been waited on).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.1.
+.SH NOTES
+.SS PID file descriptors
+The
+.I pidfd
+argument is a PID file descriptor,
+a file descriptor that refers to  process.
+Such a file descriptor can be obtained in any of the following ways:
+.IP \[bu] 3
+by opening a
+.IR /proc/ pid
+directory;
+.IP \[bu]
+using
+.BR pidfd_open (2);
+or
+.IP \[bu]
+via the PID file descriptor that is returned by a call to
+.BR clone (2)
+or
+.BR clone3 (2)
+that specifies the
+.B CLONE_PIDFD
+flag.
+.P
+The
+.BR pidfd_send_signal ()
+system call allows the avoidance of race conditions that occur
+when using traditional interfaces (such as
+.BR kill (2))
+to signal a process.
+The problem is that the traditional interfaces specify the target process
+via a process ID (PID),
+with the result that the sender may accidentally send a signal to
+the wrong process if the originally intended target process
+has terminated and its PID has been recycled for another process.
+By contrast,
+a PID file descriptor is a stable reference to a specific process;
+if that process terminates,
+.BR pidfd_send_signal ()
+fails with the error
+.BR ESRCH .
+.SH EXAMPLES
+.\" SRC BEGIN (pidfd_send_signal.c)
+.EX
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <limits.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+static int
+pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
+                  unsigned int flags)
+{
+    return syscall(SYS_pidfd_send_signal, pidfd, sig, info, flags);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int        pidfd, sig;
+    char       path[PATH_MAX];
+    siginfo_t  info;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <pid> <signal>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    sig = atoi(argv[2]);
+\&
+    /* Obtain a PID file descriptor by opening the /proc/PID directory
+       of the target process. */
+\&
+    snprintf(path, sizeof(path), "/proc/%s", argv[1]);
+\&
+    pidfd = open(path, O_RDONLY);
+    if (pidfd == \-1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Populate a \[aq]siginfo_t\[aq] structure for use with
+       pidfd_send_signal(). */
+\&
+    memset(&info, 0, sizeof(info));
+    info.si_code = SI_QUEUE;
+    info.si_signo = sig;
+    info.si_errno = 0;
+    info.si_uid = getuid();
+    info.si_pid = getpid();
+    info.si_value.sival_int = 1234;
+\&
+    /* Send the signal. */
+\&
+    if (pidfd_send_signal(pidfd, sig, &info, 0) == \-1) {
+        perror("pidfd_send_signal");
+        exit(EXIT_FAILURE);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clone (2),
+.BR kill (2),
+.BR pidfd_open (2),
+.BR rt_sigqueueinfo (2),
+.BR sigaction (2),
+.BR pid_namespaces (7),
+.BR signal (7)
diff --git a/man/man2/pipe.2 b/man/man2/pipe.2
new file mode 100644
index 000000000..a440ad401
--- /dev/null
+++ b/man/man2/pipe.2
@@ -0,0 +1,304 @@
+.\" Copyright (C) 2005, 2008, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" (A few fragments remain from an earlier (1992) version by
+.\" Drew Eckhardt <drew@cs.colorado.edu>.)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-23 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2005, mtk: added an example program
+.\" Modified 2008-01-09, mtk: rewrote DESCRIPTION; minor additions
+.\"     to EXAMPLE text.
+.\" 2008-10-10, mtk: add description of pipe2()
+.\"
+.TH pipe 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pipe, pipe2 \- create pipe
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int pipe(int " pipefd [2]);
+.P
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.BR "#include <fcntl.h>" "              /* Definition of " O_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int pipe2(int " pipefd "[2], int " flags );
+.P
+/* On Alpha, IA-64, MIPS, SuperH, and SPARC/SPARC64, pipe() has the
+   following prototype; see VERSIONS */
+.P
+.B #include <unistd.h>
+.P
+.B struct fd_pair {
+.B "    long fd[2];"
+.B "};"
+.B struct fd_pair pipe(void);
+.fi
+.SH DESCRIPTION
+.BR pipe ()
+creates a pipe, a unidirectional data channel that
+can be used for interprocess communication.
+The array
+.I pipefd
+is used to return two file descriptors referring to the ends of the pipe.
+.I pipefd[0]
+refers to the read end of the pipe.
+.I pipefd[1]
+refers to the write end of the pipe.
+Data written to the write end of the pipe is buffered by the kernel
+until it is read from the read end of the pipe.
+For further details, see
+.BR pipe (7).
+.P
+If
+.I flags
+is 0, then
+.BR pipe2 ()
+is the same as
+.BR pipe ().
+The following values can be bitwise ORed in
+.I flags
+to obtain different behavior:
+.TP
+.B O_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the two new file descriptors.
+See the description of the same flag in
+.BR open (2)
+for reasons why this may be useful.
+.TP
+.BR O_DIRECT " (since Linux 3.4)"
+.\" commit 9883035ae7edef3ec62ad215611cb8e17d6a1a5d
+Create a pipe that performs I/O in "packet" mode.
+Each
+.BR write (2)
+to the pipe is dealt with as a separate packet, and
+.BR read (2)s
+from the pipe will read one packet at a time.
+Note the following points:
+.RS
+.IP \[bu] 3
+Writes of greater than
+.B PIPE_BUF
+bytes (see
+.BR pipe (7))
+will be split into multiple packets.
+The constant
+.B PIPE_BUF
+is defined in
+.IR <limits.h> .
+.IP \[bu]
+If a
+.BR read (2)
+specifies a buffer size that is smaller than the next packet,
+then the requested number of bytes are read,
+and the excess bytes in the packet are discarded.
+Specifying a buffer size of
+.B PIPE_BUF
+will be sufficient to read the largest possible packets
+(see the previous point).
+.IP \[bu]
+Zero-length packets are not supported.
+(A
+.BR read (2)
+that specifies a buffer size of zero is a no-op, and returns 0.)
+.RE
+.IP
+Older kernels that do not support this flag will indicate this via an
+.B EINVAL
+error.
+.IP
+Since Linux 4.5,
+.\" commit 0dbf5f20652108106cb822ad7662c786baaa03ff
+.\" FIXME . But, it is not possible to specify O_DIRECT when opening a FIFO
+it is possible to change the
+.B O_DIRECT
+setting of a pipe file descriptor using
+.BR fcntl (2).
+.TP
+.B O_NONBLOCK
+Set the
+.B O_NONBLOCK
+file status flag on the open file descriptions
+referred to by the new file descriptors.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
+.TP
+.B O_NOTIFICATION_PIPE
+Since Linux 5.8,
+.\" commit c73be61cede5882f9605a852414db559c0ebedfd
+general notification mechanism is built on the top of the pipe where
+kernel splices notification messages into pipes opened by user space.
+The owner of the pipe has to tell the kernel which sources of events to watch
+and filters can also be applied to select
+which subevents should be placed into the pipe.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned,
+.I errno
+is set to indicate the error, and
+.I pipefd
+is left unchanged.
+.P
+On Linux (and other systems),
+.BR pipe ()
+does not modify
+.I pipefd
+on failure.
+A requirement standardizing this behavior was added in POSIX.1-2008 TC2.
+.\" http://austingroupbugs.net/view.php?id=467
+The Linux-specific
+.BR pipe2 ()
+system call
+likewise does not modify
+.I pipefd
+on failure.
+.SH ERRORS
+.TP
+.B EFAULT
+.I pipefd
+is not valid.
+.TP
+.B EINVAL
+.RB ( pipe2 ())
+Invalid value in
+.IR flags .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENFILE
+The user hard limit on memory that can be allocated for pipes
+has been reached and the caller is not privileged; see
+.BR pipe (7).
+.TP
+.B ENOPKG
+.RB ( pipe2 ())
+.B O_NOTIFICATION_PIPE
+was passed in
+.I flags
+and support for notifications
+.RB ( CONFIG_WATCH_QUEUE )
+is not compiled into the kernel.
+.SH VERSIONS
+.\" See http://math-atlas.sourceforge.net/devel/assembly/64.psabi.1.33.ps.Z
+.\" for example, section 3.2.1 "Registers and the Stack Frame".
+The System V ABI on some architectures allows the use of more than one register
+for returning multiple values; several architectures
+(namely, Alpha, IA-64, MIPS, SuperH, and SPARC/SPARC64)
+(ab)use this feature in order to implement the
+.BR pipe ()
+system call in a functional manner:
+the call doesn't take any arguments and returns
+a pair of file descriptors as the return value on success.
+The glibc
+.BR pipe ()
+wrapper function transparently deals with this.
+See
+.BR syscall (2)
+for information regarding registers used for storing second file descriptor.
+.SH STANDARDS
+.TP
+.BR pipe ()
+POSIX.1-2008.
+.TP
+.BR pipe2 ()
+Linux.
+.SH HISTORY
+.TP
+.BR pipe ()
+POSIX.1-2001.
+.TP
+.BR pipe2 ()
+Linux 2.6.27,
+glibc 2.9.
+.SH EXAMPLES
+.\" fork.2 refers to this example program.
+The following program creates a pipe, and then
+.BR fork (2)s
+to create a child process;
+the child inherits a duplicate set of file
+descriptors that refer to the same pipe.
+After the
+.BR fork (2),
+each process closes the file descriptors that it doesn't need for the pipe
+(see
+.BR pipe (7)).
+The parent then writes the string contained in the program's
+command-line argument to the pipe,
+and the child reads this string a byte at a time from the pipe
+and echoes it on standard output.
+.SS Program source
+.\" SRC BEGIN (pipe.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int    pipefd[2];
+    char   buf;
+    pid_t  cpid;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <string>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (pipe(pipefd) == \-1) {
+        perror("pipe");
+        exit(EXIT_FAILURE);
+    }
+\&
+    cpid = fork();
+    if (cpid == \-1) {
+        perror("fork");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (cpid == 0) {    /* Child reads from pipe */
+        close(pipefd[1]);          /* Close unused write end */
+\&
+        while (read(pipefd[0], &buf, 1) > 0)
+            write(STDOUT_FILENO, &buf, 1);
+\&
+        write(STDOUT_FILENO, "\en", 1);
+        close(pipefd[0]);
+        _exit(EXIT_SUCCESS);
+\&
+    } else {            /* Parent writes argv[1] to pipe */
+        close(pipefd[0]);          /* Close unused read end */
+        write(pipefd[1], argv[1], strlen(argv[1]));
+        close(pipefd[1]);          /* Reader will see EOF */
+        wait(NULL);                /* Wait for child */
+        exit(EXIT_SUCCESS);
+    }
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fork (2),
+.BR read (2),
+.BR socketpair (2),
+.BR splice (2),
+.BR tee (2),
+.BR vmsplice (2),
+.BR write (2),
+.BR popen (3),
+.BR pipe (7)
diff --git a/man/man2/pipe2.2 b/man/man2/pipe2.2
new file mode 100644
index 000000000..980e2406b
--- /dev/null
+++ b/man/man2/pipe2.2
@@ -0,0 +1 @@
+.so man2/pipe.2
diff --git a/man/man2/pivot_root.2 b/man/man2/pivot_root.2
new file mode 100644
index 000000000..9cb5d9b25
--- /dev/null
+++ b/man/man2/pivot_root.2
@@ -0,0 +1,409 @@
+.\" Copyright (C) 2019 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" A very few fragments remain from an earlier page written by
+.\" Werner Almesberger in 2000
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pivot_root 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pivot_root \- change the root mount
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_pivot_root, const char *" new_root \
+", const char *" put_old );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR pivot_root (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR pivot_root ()
+changes the root mount in the mount namespace of the calling process.
+More precisely, it moves the root mount to the
+directory \fIput_old\fP and makes \fInew_root\fP the new root mount.
+The calling process must have the
+.B CAP_SYS_ADMIN
+capability in the user namespace that owns the caller's mount namespace.
+.P
+.BR pivot_root ()
+changes the root directory and the current working directory
+of each process or thread in the same mount namespace to
+.I new_root
+if they point to the old root directory.
+(See also NOTES.)
+On the other hand,
+.BR pivot_root ()
+does not change the caller's current working directory
+(unless it is on the old root directory),
+and thus it should be followed by a
+\fBchdir("/")\fP call.
+.P
+The following restrictions apply:
+.IP \[bu] 3
+.I new_root
+and
+.I put_old
+must be directories.
+.IP \[bu]
+.I new_root
+and
+.I put_old
+must not be on the same mount as the current root.
+.IP \[bu]
+\fIput_old\fP must be at or underneath \fInew_root\fP;
+that is, adding some nonnegative
+number of "\fI/..\fP" suffixes to the pathname pointed to by
+.I put_old
+must yield the same directory as \fInew_root\fP.
+.IP \[bu]
+.I new_root
+must be a path to a mount point, but can't be
+.IR \[dq]/\[dq] .
+A path that is not already a mount point can be converted into one by
+bind mounting the path onto itself.
+.IP \[bu]
+The propagation type of the parent mount of
+.I new_root
+and the parent mount of the current root directory must not be
+.BR MS_SHARED ;
+similarly, if
+.I put_old
+is an existing mount point, its propagation type must not be
+.BR MS_SHARED .
+These restrictions ensure that
+.BR pivot_root ()
+never propagates any changes to another mount namespace.
+.IP \[bu]
+The current root directory must be a mount point.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+\fIerrno\fP is set to indicate the error.
+.SH ERRORS
+.BR pivot_root ()
+may fail with any of the same errors as
+.BR stat (2).
+Additionally, it may fail with the following errors:
+.TP
+.B EBUSY
+.\" Reconfirmed that the following error occurs on Linux 5.0 by
+.\" specifying 'new_root' as "/rootfs" and 'put_old' as
+.\" "/rootfs/oldrootfs", and *not* bind mounting "/rootfs" on top of
+.\" itself. Of course, this is an odd situation, since a later check
+.\" in the kernel code will in any case yield EINVAL if 'new_root' is
+.\" not a mount point. However, when the system call was first added,
+.\" 'new_root' was not required to be a mount point. So, this
+.\" error is nowadays probably just the result of crufty accumulation.
+.\" This error can also occur if we bind mount "/" on top of itself
+.\" and try to specify "/" as the 'new' (again, an odd situation). So,
+.\" the EBUSY check in the kernel does still seem necessary to prevent
+.\" that case.  Furthermore, the "or put_old" piece is probably
+.\" redundant text (although the check is in the kernel), since,
+.\" in another check, 'put_old' is required to be under 'new_root'.
+.I new_root
+or
+.I put_old
+is on the current root mount.
+(This error covers the pathological case where
+.I new_root
+is
+.IR \[dq]/\[dq] .)
+.TP
+.B EINVAL
+.I new_root
+is not a mount point.
+.TP
+.B EINVAL
+\fIput_old\fP is not at or underneath \fInew_root\fP.
+.TP
+.B EINVAL
+The current root directory is not a mount point
+(because of an earlier
+.BR chroot (2)).
+.TP
+.B EINVAL
+The current root is on the rootfs (initial ramfs) mount; see NOTES.
+.TP
+.B EINVAL
+Either the mount point at
+.IR new_root ,
+or the parent mount of that mount point,
+has propagation type
+.BR MS_SHARED .
+.TP
+.B EINVAL
+.I put_old
+is a mount point and has the propagation type
+.BR MS_SHARED .
+.TP
+.B ENOTDIR
+\fInew_root\fP or \fIput_old\fP is not a directory.
+.TP
+.B EPERM
+The calling process does not have the
+.B CAP_SYS_ADMIN
+capability.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.3.41.
+.SH NOTES
+A command-line interface for this system call is provided by
+.BR pivot_root (8).
+.P
+.BR pivot_root ()
+allows the caller to switch to a new root filesystem while at the same time
+placing the old root mount at a location under
+.I new_root
+from where it can subsequently be unmounted.
+(The fact that it moves all processes that have a root directory
+or current working directory on the old root directory to the
+new root frees the old root directory of users,
+allowing the old root mount to be unmounted more easily.)
+.P
+One use of
+.BR pivot_root ()
+is during system startup, when the
+system mounts a temporary root filesystem (e.g., an
+.BR initrd (4)),
+then mounts the real root filesystem, and eventually turns the latter into
+the root directory of all relevant processes and threads.
+A modern use is to set up a root filesystem during
+the creation of a container.
+.P
+The fact that
+.BR pivot_root ()
+modifies process root and current working directories in the
+manner noted in DESCRIPTION
+is necessary in order to prevent kernel threads from keeping the old
+root mount busy with their root and current working directories,
+even if they never access
+the filesystem in any way.
+.P
+The rootfs (initial ramfs) cannot be
+.BR pivot_root ()ed.
+The recommended method of changing the root filesystem in this case is
+to delete everything in rootfs, overmount rootfs with the new root, attach
+.IR stdin / stdout / stderr
+to the new
+.IR /dev/console ,
+and exec the new
+.BR init (1).
+Helper programs for this process exist; see
+.BR switch_root (8).
+.\"
+.SS pivot_root(\[dq].\[dq], \[dq].\[dq])
+.I new_root
+and
+.I put_old
+may be the same directory.
+In particular, the following sequence allows a pivot-root operation
+without needing to create and remove a temporary directory:
+.P
+.in +4n
+.EX
+chdir(new_root);
+pivot_root(".", ".");
+umount2(".", MNT_DETACH);
+.EE
+.in
+.P
+This sequence succeeds because the
+.BR pivot_root ()
+call stacks the old root mount point
+on top of the new root mount point at
+.IR / .
+At that point, the calling process's root directory and current
+working directory refer to the new root mount point
+.RI ( new_root ).
+During the subsequent
+.BR umount ()
+call, resolution of
+.I \[dq].\[dq]
+starts with
+.I new_root
+and then moves up the list of mounts stacked at
+.IR / ,
+with the result that old root mount point is unmounted.
+.\"
+.SS Historical notes
+For many years, this manual page carried the following text:
+.RS
+.P
+.BR pivot_root ()
+may or may not change the current root and the current
+working directory of any processes or threads which use the old
+root directory.
+The caller of
+.BR pivot_root ()
+must ensure that processes with root or current working directory
+at the old root operate correctly in either case.
+An easy way to ensure this is to change their
+root and current working directory to \fInew_root\fP before invoking
+.BR pivot_root ().
+.RE
+.P
+This text, written before the system call implementation was
+even finalized in the kernel, was probably intended to warn users
+at that time that the implementation might change before final release.
+However, the behavior stated in DESCRIPTION
+has remained consistent since this system call
+was first implemented and will not change now.
+.SH EXAMPLES
+.\" FIXME
+.\" Would it be better, because simpler, to use unshare(2)
+.\" rather than clone(2) in the example below?
+The program below demonstrates the use of
+.BR pivot_root ()
+inside a mount namespace that is created using
+.BR clone (2).
+After pivoting to the root directory named in the program's
+first command-line argument, the child created by
+.BR clone (2)
+then executes the program named in the remaining command-line arguments.
+.P
+We demonstrate the program by creating a directory that will serve as
+the new root filesystem and placing a copy of the (statically linked)
+.BR busybox (1)
+executable in that directory.
+.P
+.in +4n
+.EX
+$ \fBmkdir /tmp/rootfs\fP
+$ \fBls \-id /tmp/rootfs\fP    # Show inode number of new root directory
+319459 /tmp/rootfs
+$ \fBcp $(which busybox) /tmp/rootfs\fP
+$ \fBPS1=\[aq]bbsh$ \[aq] sudo ./pivot_root_demo /tmp/rootfs /busybox sh\fP
+bbsh$ \fBPATH=/\fP
+bbsh$ \fBbusybox ln busybox ln\fP
+bbsh$ \fBln busybox echo\fP
+bbsh$ \fBln busybox ls\fP
+bbsh$ \fBls\fP
+busybox  echo     ln       ls
+bbsh$ \fBls \-id /\fP          # Compare with inode number above
+319459 /
+bbsh$ \fBecho \[aq]hello world\[aq]\fP
+hello world
+.EE
+.in
+.SS Program source
+\&
+.P
+.\" SRC BEGIN (pivot_root.c)
+.EX
+/* pivot_root_demo.c */
+\&
+#define _GNU_SOURCE
+#include <err.h>
+#include <limits.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <unistd.h>
+\&
+static int
+pivot_root(const char *new_root, const char *put_old)
+{
+    return syscall(SYS_pivot_root, new_root, put_old);
+}
+\&
+#define STACK_SIZE (1024 * 1024)
+\&
+static int              /* Startup function for cloned child */
+child(void *arg)
+{
+    char        path[PATH_MAX];
+    char        **args = arg;
+    char        *new_root = args[0];
+    const char  *put_old = "/oldrootfs";
+\&
+    /* Ensure that \[aq]new_root\[aq] and its parent mount don\[aq]t have
+       shared propagation (which would cause pivot_root() to
+       return an error), and prevent propagation of mount
+       events to the initial mount namespace. */
+\&
+    if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL) == \-1)
+        err(EXIT_FAILURE, "mount\-MS_PRIVATE");
+\&
+    /* Ensure that \[aq]new_root\[aq] is a mount point. */
+\&
+    if (mount(new_root, new_root, NULL, MS_BIND, NULL) == \-1)
+        err(EXIT_FAILURE, "mount\-MS_BIND");
+\&
+    /* Create directory to which old root will be pivoted. */
+\&
+    snprintf(path, sizeof(path), "%s/%s", new_root, put_old);
+    if (mkdir(path, 0777) == \-1)
+        err(EXIT_FAILURE, "mkdir");
+\&
+    /* And pivot the root filesystem. */
+\&
+    if (pivot_root(new_root, path) == \-1)
+        err(EXIT_FAILURE, "pivot_root");
+\&
+    /* Switch the current working directory to "/". */
+\&
+    if (chdir("/") == \-1)
+        err(EXIT_FAILURE, "chdir");
+\&
+    /* Unmount old root and remove mount point. */
+\&
+    if (umount2(put_old, MNT_DETACH) == \-1)
+        perror("umount2");
+    if (rmdir(put_old) == \-1)
+        perror("rmdir");
+\&
+    /* Execute the command specified in argv[1]... */
+\&
+    execv(args[1], &args[1]);
+    err(EXIT_FAILURE, "execv");
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    char *stack;
+\&
+    /* Create a child process in a new mount namespace. */
+\&
+    stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE,
+                 MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, \-1, 0);
+    if (stack == MAP_FAILED)
+        err(EXIT_FAILURE, "mmap");
+\&
+    if (clone(child, stack + STACK_SIZE,
+              CLONE_NEWNS | SIGCHLD, &argv[1]) == \-1)
+        err(EXIT_FAILURE, "clone");
+\&
+    /* Parent falls through to here; wait for child. */
+\&
+    if (wait(NULL) == \-1)
+        err(EXIT_FAILURE, "wait");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR chdir (2),
+.BR chroot (2),
+.BR mount (2),
+.BR stat (2),
+.BR initrd (4),
+.BR mount_namespaces (7),
+.BR pivot_root (8),
+.BR switch_root (8)
diff --git a/man/man2/pkey_alloc.2 b/man/man2/pkey_alloc.2
new file mode 100644
index 000000000..0f706e7da
--- /dev/null
+++ b/man/man2/pkey_alloc.2
@@ -0,0 +1,115 @@
+.\" Copyright (C) 2016 Intel Corporation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pkey_alloc 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pkey_alloc, pkey_free \- allocate or free a protection key
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sys/mman.h>
+.P
+.BI "int pkey_alloc(unsigned int " flags ", unsigned int " access_rights ");"
+.BI "int pkey_free(int " pkey ");"
+.fi
+.SH DESCRIPTION
+.BR pkey_alloc ()
+allocates a protection key (pkey) and allows it to be passed to
+.BR pkey_mprotect (2).
+.P
+The
+.BR pkey_alloc ()
+.I flags
+is reserved for future use and currently must always be specified as 0.
+.P
+The
+.BR pkey_alloc ()
+.I access_rights
+argument may contain zero or more disable operations:
+.TP
+.B PKEY_DISABLE_ACCESS
+Disable all data access to memory covered by the returned protection key.
+.TP
+.B PKEY_DISABLE_WRITE
+Disable write access to memory covered by the returned protection key.
+.P
+.BR pkey_free ()
+frees a protection key and makes it available for later
+allocations.
+After a protection key has been freed, it may no longer be used
+in any protection-key-related operations.
+.P
+An application should not call
+.BR pkey_free ()
+on any protection key which has been assigned to an address
+range by
+.BR pkey_mprotect (2)
+and which is still in use.
+The behavior in this case is undefined and may result in an error.
+.SH RETURN VALUE
+On success,
+.BR pkey_alloc ()
+returns a positive protection key value.
+On success,
+.BR pkey_free ()
+returns zero.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.IR pkey ,
+.IR flags ,
+or
+.I access_rights
+is invalid.
+.TP
+.B ENOSPC
+.RB ( pkey_alloc ())
+All protection keys available for the current process have
+been allocated.
+The number of keys available is architecture-specific and
+implementation-specific and may be reduced by kernel-internal use
+of certain keys.
+There are currently 15 keys available to user programs on x86.
+.IP
+This error will also be returned if the processor or operating system
+does not support protection keys.
+Applications should always be prepared to handle this error, since
+factors outside of the application's control can reduce the number
+of available pkeys.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 4.9,
+glibc 2.27.
+.SH NOTES
+.BR pkey_alloc ()
+is always safe to call regardless of whether or not the operating system
+supports protection keys.
+It can be used in lieu of any other mechanism for detecting pkey support
+and will simply fail with the error
+.B ENOSPC
+if the operating system has no pkey support.
+.P
+The kernel guarantees that the contents of the hardware rights
+register (PKRU) will be preserved only for allocated protection
+keys.
+Any time a key is unallocated (either before the first call
+returning that key from
+.BR pkey_alloc ()
+or after it is freed via
+.BR pkey_free ()),
+the kernel may make arbitrary changes to the parts of the
+rights register affecting access to that key.
+.SH EXAMPLES
+See
+.BR pkeys (7).
+.SH SEE ALSO
+.BR pkey_mprotect (2),
+.BR pkeys (7)
diff --git a/man/man2/pkey_free.2 b/man/man2/pkey_free.2
new file mode 100644
index 000000000..5b524cbbf
--- /dev/null
+++ b/man/man2/pkey_free.2
@@ -0,0 +1 @@
+.so man2/pkey_alloc.2
diff --git a/man/man2/pkey_mprotect.2 b/man/man2/pkey_mprotect.2
new file mode 100644
index 000000000..b4f9309a3
--- /dev/null
+++ b/man/man2/pkey_mprotect.2
@@ -0,0 +1 @@
+.so man2/mprotect.2
diff --git a/man/man2/poll.2 b/man/man2/poll.2
new file mode 100644
index 000000000..f1a5a9795
--- /dev/null
+++ b/man/man2/poll.2
@@ -0,0 +1,649 @@
+.\" Copyright (C) 2006, 2019 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Additions from Richard Gooch <rgooch@atnf.CSIRO.AU> and aeb, 971207
+.\" 2006-03-13, mtk, Added ppoll() + various other rewordings
+.\" 2006-07-01, mtk, Added POLLRDHUP + various other wording and
+.\"	formatting changes.
+.\"
+.TH poll 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+poll, ppoll \- wait for some event on a file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <poll.h>
+.P
+.BI "int poll(struct pollfd *" fds ", nfds_t " nfds ", int " timeout );
+.P
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <poll.h>
+.P
+.BI "int ppoll(struct pollfd *" fds ", nfds_t " nfds ,
+.BI "          const struct timespec *_Nullable " tmo_p ,
+.BI "          const sigset_t *_Nullable " sigmask );
+.fi
+.SH DESCRIPTION
+.BR poll ()
+performs a similar task to
+.BR select (2):
+it waits for one of a set of file descriptors to become ready
+to perform I/O.
+The Linux-specific
+.BR epoll (7)
+API performs a similar task, but offers features beyond those found in
+.BR poll ().
+.P
+The set of file descriptors to be monitored is specified in the
+.I fds
+argument, which is an array of structures of the following form:
+.P
+.in +4n
+.EX
+struct pollfd {
+    int   fd;         /* file descriptor */
+    short events;     /* requested events */
+    short revents;    /* returned events */
+};
+.EE
+.in
+.P
+The caller should specify the number of items in the
+.I fds
+array in
+.IR nfds .
+.P
+The field
+.I fd
+contains a file descriptor for an open file.
+If this field is negative, then the corresponding
+.I events
+field is ignored and the
+.I revents
+field returns zero.
+(This provides an easy way of ignoring a
+file descriptor for a single
+.BR poll ()
+call: simply set the
+.I fd
+field to its bitwise complement.)
+.P
+The field
+.I events
+is an input parameter, a bit mask specifying the events the application
+is interested in for the file descriptor
+.IR fd .
+This field may be specified as zero,
+in which case the only events that can be returned in
+.I revents
+are
+.BR POLLHUP ,
+.BR POLLERR ,
+and
+.B POLLNVAL
+(see below).
+.P
+The field
+.I revents
+is an output parameter, filled by the kernel with the events that
+actually occurred.
+The bits returned in
+.I revents
+can include any of those specified in
+.IR events ,
+or one of the values
+.BR POLLERR ,
+.BR POLLHUP ,
+or
+.BR POLLNVAL .
+(These three bits are meaningless in the
+.I events
+field, and will be set in the
+.I revents
+field whenever the corresponding condition is true.)
+.P
+If none of the events requested (and no error) has occurred for any
+of the file descriptors, then
+.BR poll ()
+blocks until one of the events occurs.
+.P
+The
+.I timeout
+argument specifies the number of milliseconds that
+.BR poll ()
+should block waiting for a file descriptor to become ready.
+The call will block until either:
+.IP \[bu] 3
+a file descriptor becomes ready;
+.IP \[bu]
+the call is interrupted by a signal handler; or
+.IP \[bu]
+the timeout expires.
+.P
+Being "ready" means that the requested operation will not block; thus,
+.BR poll ()ing
+regular files,
+block devices,
+and other files with no reasonable polling semantic
+.I always
+returns instantly as ready to read and write.
+.P
+Note that the
+.I timeout
+interval will be rounded up to the system clock granularity,
+and kernel scheduling delays mean that the blocking interval
+may overrun by a small amount.
+Specifying a negative value in
+.I timeout
+means an infinite timeout.
+Specifying a
+.I timeout
+of zero causes
+.BR poll ()
+to return immediately, even if no file descriptors are ready.
+.P
+The bits that may be set/returned in
+.I events
+and
+.I revents
+are defined in \fI<poll.h>\fP:
+.TP
+.B POLLIN
+There is data to read.
+.TP
+.B POLLPRI
+There is some exceptional condition on the file descriptor.
+Possibilities include:
+.RS
+.IP \[bu] 3
+There is out-of-band data on a TCP socket (see
+.BR tcp (7)).
+.IP \[bu]
+A pseudoterminal master in packet mode has seen a state change on the slave
+(see
+.BR ioctl_tty (2)).
+.IP \[bu]
+A
+.I cgroup.events
+file has been modified (see
+.BR cgroups (7)).
+.RE
+.TP
+.B POLLOUT
+Writing is now possible, though a write larger than the available space
+in a socket or pipe will still block (unless
+.B O_NONBLOCK
+is set).
+.TP
+.BR POLLRDHUP " (since Linux 2.6.17)"
+Stream socket peer closed connection,
+or shut down writing half of connection.
+The
+.B _GNU_SOURCE
+feature test macro must be defined
+(before including
+.I any
+header files)
+in order to obtain this definition.
+.TP
+.B POLLERR
+Error condition (only returned in
+.IR revents ;
+ignored in
+.IR events ).
+This bit is also set for a file descriptor referring
+to the write end of a pipe when the read end has been closed.
+.TP
+.B POLLHUP
+Hang up (only returned in
+.IR revents ;
+ignored in
+.IR events ).
+Note that when reading from a channel such as a pipe or a stream socket,
+this event merely indicates that the peer closed its end of the channel.
+Subsequent reads from the channel will return 0 (end of file)
+only after all outstanding data in the channel has been consumed.
+.TP
+.B POLLNVAL
+Invalid request:
+.I fd
+not open (only returned in
+.IR revents ;
+ignored in
+.IR events ).
+.P
+When compiling with
+.B _XOPEN_SOURCE
+defined, one also has the following,
+which convey no further information beyond the bits listed above:
+.TP
+.B POLLRDNORM
+Equivalent to
+.BR POLLIN .
+.TP
+.B POLLRDBAND
+Priority band data can be read (generally unused on Linux).
+.\" POLLRDBAND is used in the DECnet protocol.
+.TP
+.B POLLWRNORM
+Equivalent to
+.BR POLLOUT .
+.TP
+.B POLLWRBAND
+Priority data may be written.
+.P
+Linux also knows about, but does not use
+.BR POLLMSG .
+.SS ppoll()
+The relationship between
+.BR poll ()
+and
+.BR ppoll ()
+is analogous to the relationship between
+.BR select (2)
+and
+.BR pselect (2):
+like
+.BR pselect (2),
+.BR ppoll ()
+allows an application to safely wait until either a file descriptor
+becomes ready or until a signal is caught.
+.P
+Other than the difference in the precision of the
+.I timeout
+argument, the following
+.BR ppoll ()
+call:
+.P
+.in +4n
+.EX
+ready = ppoll(&fds, nfds, tmo_p, &sigmask);
+.EE
+.in
+.P
+is nearly equivalent to
+.I atomically
+executing the following calls:
+.P
+.in +4n
+.EX
+sigset_t origmask;
+int timeout;
+\&
+timeout = (tmo_p == NULL) ? \-1 :
+          (tmo_p\->tv_sec * 1000 + tmo_p\->tv_nsec / 1000000);
+pthread_sigmask(SIG_SETMASK, &sigmask, &origmask);
+ready = poll(&fds, nfds, timeout);
+pthread_sigmask(SIG_SETMASK, &origmask, NULL);
+.EE
+.in
+.P
+The above code segment is described as
+.I nearly
+equivalent because whereas a negative
+.I timeout
+value for
+.BR poll ()
+is interpreted as an infinite timeout, a negative value expressed in
+.I *tmo_p
+results in an error from
+.BR ppoll ().
+.P
+See the description of
+.BR pselect (2)
+for an explanation of why
+.BR ppoll ()
+is necessary.
+.P
+If the
+.I sigmask
+argument is specified as NULL, then
+no signal mask manipulation is performed
+(and thus
+.BR ppoll ()
+differs from
+.BR poll ()
+only in the precision of the
+.I timeout
+argument).
+.P
+The
+.I tmo_p
+argument specifies an upper limit on the amount of time that
+.BR ppoll ()
+will block.
+This argument is a pointer to a
+.BR timespec (3)
+structure.
+.P
+If
+.I tmo_p
+is specified as NULL, then
+.BR ppoll ()
+can block indefinitely.
+.SH RETURN VALUE
+On success,
+.BR poll ()
+returns a nonnegative value which is the number of elements in the
+.I pollfds
+whose
+.I revents
+fields have been set to a nonzero value (indicating an event or an error).
+A return value of zero indicates that the system call timed out
+before any file descriptors became ready.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I fds
+points outside the process's accessible address space.
+The array given as argument was not contained in the calling program's
+address space.
+.TP
+.B EINTR
+A signal occurred before any requested event; see
+.BR signal (7).
+.TP
+.B EINVAL
+The
+.I nfds
+value exceeds the
+.B RLIMIT_NOFILE
+value.
+.TP
+.B EINVAL
+.RB ( ppoll ())
+The timeout value expressed in
+.I *tmo_p
+is invalid (negative).
+.TP
+.B ENOMEM
+Unable to allocate memory for kernel data structures.
+.SH VERSIONS
+On some other UNIX systems,
+.\" Darwin, according to a report by Jeremy Sequoia, relayed by Josh Triplett
+.BR poll ()
+can fail with the error
+.B EAGAIN
+if the system fails to allocate kernel-internal resources, rather than
+.B ENOMEM
+as Linux does.
+POSIX permits this behavior.
+Portable programs may wish to check for
+.B EAGAIN
+and loop, just as with
+.BR EINTR .
+.P
+Some implementations define the nonstandard constant
+.B INFTIM
+with the value \-1 for use as a
+.I timeout
+for
+.BR poll ().
+This constant is not provided in glibc.
+.SS C library/kernel differences
+The Linux
+.BR ppoll ()
+system call modifies its
+.I tmo_p
+argument.
+However, the glibc wrapper function hides this behavior
+by using a local variable for the timeout argument that
+is passed to the system call.
+Thus, the glibc
+.BR ppoll ()
+function does not modify its
+.I tmo_p
+argument.
+.P
+The raw
+.BR ppoll ()
+system call has a fifth argument,
+.IR "size_t sigsetsize" ,
+which specifies the size in bytes of the
+.I sigmask
+argument.
+The glibc
+.BR ppoll ()
+wrapper function specifies this argument as a fixed value
+(equal to
+.IR sizeof(kernel_sigset_t) ).
+See
+.BR sigprocmask (2)
+for a discussion on the differences between the kernel and the libc
+notion of the sigset.
+.SH STANDARDS
+.TP
+.BR poll ()
+POSIX.1-2008.
+.TP
+.BR ppoll ()
+Linux.
+.\" FIXME .
+.\" ppoll() is proposed for inclusion in POSIX:
+.\" https://www.austingroupbugs.net/view.php?id=1263
+.\" NetBSD 3.0 has a pollts() which is like Linux ppoll().
+.SH HISTORY
+.TP
+.BR poll ()
+POSIX.1-2001.
+Linux 2.1.23.
+.IP
+On older kernels that lack this system call,
+the glibc
+.BR poll ()
+wrapper function provides emulation using
+.BR select (2).
+.TP
+.BR ppoll ()
+Linux 2.6.16,
+glibc 2.4.
+.SH NOTES
+The operation of
+.BR poll ()
+and
+.BR ppoll ()
+is not affected by the
+.B O_NONBLOCK
+flag.
+.P
+For a discussion of what may happen if a file descriptor being monitored by
+.BR poll ()
+is closed in another thread, see
+.BR select (2).
+.SH BUGS
+See the discussion of spurious readiness notifications under the
+BUGS section of
+.BR select (2).
+.SH EXAMPLES
+The program below opens each of the files named in its command-line
+arguments and monitors the resulting file descriptors for readiness to read
+.RB ( POLLIN ).
+The program loops, repeatedly using
+.BR poll ()
+to monitor the file descriptors,
+printing the number of ready file descriptors on return.
+For each ready file descriptor, the program:
+.IP \[bu] 3
+displays the returned
+.I revents
+field in a human-readable form;
+.IP \[bu]
+if the file descriptor is readable, reads some data from it,
+and displays that data on standard output; and
+.IP \[bu]
+if the file descriptor was not readable,
+but some other event occurred (presumably
+.BR POLLHUP ),
+closes the file descriptor.
+.P
+Suppose we run the program in one terminal, asking it to open a FIFO:
+.P
+.in +4n
+.EX
+$ \fBmkfifo myfifo\fP
+$ \fB./poll_input myfifo\fP
+.EE
+.in
+.P
+In a second terminal window, we then open the FIFO for writing,
+write some data to it, and close the FIFO:
+.P
+.in +4n
+.EX
+$ \fBecho aaaaabbbbbccccc > myfifo\fP
+.EE
+.in
+.P
+In the terminal where we are running the program, we would then see:
+.P
+.in +4n
+.EX
+Opened "myfifo" on fd 3
+About to poll()
+Ready: 1
+  fd=3; events: POLLIN POLLHUP
+    read 10 bytes: aaaaabbbbb
+About to poll()
+Ready: 1
+  fd=3; events: POLLIN POLLHUP
+    read 6 bytes: ccccc
+\&
+About to poll()
+Ready: 1
+  fd=3; events: POLLHUP
+    closing fd 3
+All file descriptors closed; bye
+.EE
+.in
+.P
+In the above output, we see that
+.BR poll ()
+returned three times:
+.IP \[bu] 3
+On the first return, the bits returned in the
+.I revents
+field were
+.BR POLLIN ,
+indicating that the file descriptor is readable, and
+.BR POLLHUP ,
+indicating that the other end of the FIFO has been closed.
+The program then consumed some of the available input.
+.IP \[bu]
+The second return from
+.BR poll ()
+also indicated
+.B POLLIN
+and
+.BR POLLHUP ;
+the program then consumed the last of the available input.
+.IP \[bu]
+On the final return,
+.BR poll ()
+indicated only
+.B POLLHUP
+on the FIFO,
+at which point the file descriptor was closed and the program terminated.
+.\"
+.SS Program source
+\&
+.\" SRC BEGIN (poll_input.c)
+.EX
+/* poll_input.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#include <fcntl.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+int
+main(int argc, char *argv[])
+{
+    int            ready;
+    char           buf[10];
+    nfds_t         num_open_fds, nfds;
+    ssize_t        s;
+    struct pollfd  *pfds;
+\&
+    if (argc < 2) {
+       fprintf(stderr, "Usage: %s file...\en", argv[0]);
+       exit(EXIT_FAILURE);
+    }
+\&
+    num_open_fds = nfds = argc \- 1;
+    pfds = calloc(nfds, sizeof(struct pollfd));
+    if (pfds == NULL)
+        errExit("malloc");
+\&
+    /* Open each file on command line, and add it to \[aq]pfds\[aq] array. */
+\&
+    for (nfds_t j = 0; j < nfds; j++) {
+        pfds[j].fd = open(argv[j + 1], O_RDONLY);
+        if (pfds[j].fd == \-1)
+            errExit("open");
+\&
+        printf("Opened \e"%s\e" on fd %d\en", argv[j + 1], pfds[j].fd);
+\&
+        pfds[j].events = POLLIN;
+    }
+\&
+    /* Keep calling poll() as long as at least one file descriptor is
+       open. */
+\&
+    while (num_open_fds > 0) {
+        printf("About to poll()\en");
+        ready = poll(pfds, nfds, \-1);
+        if (ready == \-1)
+            errExit("poll");
+\&
+        printf("Ready: %d\en", ready);
+\&
+        /* Deal with array returned by poll(). */
+\&
+        for (nfds_t j = 0; j < nfds; j++) {
+            if (pfds[j].revents != 0) {
+                printf("  fd=%d; events: %s%s%s\en", pfds[j].fd,
+                       (pfds[j].revents & POLLIN)  ? "POLLIN "  : "",
+                       (pfds[j].revents & POLLHUP) ? "POLLHUP " : "",
+                       (pfds[j].revents & POLLERR) ? "POLLERR " : "");
+\&
+                if (pfds[j].revents & POLLIN) {
+                    s = read(pfds[j].fd, buf, sizeof(buf));
+                    if (s == \-1)
+                        errExit("read");
+                    printf("    read %zd bytes: %.*s\en",
+                           s, (int) s, buf);
+                } else {                /* POLLERR | POLLHUP */
+                    printf("    closing fd %d\en", pfds[j].fd);
+                    if (close(pfds[j].fd) == \-1)
+                        errExit("close");
+                    num_open_fds\-\-;
+                }
+            }
+        }
+    }
+\&
+    printf("All file descriptors closed; bye\en");
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR restart_syscall (2),
+.BR select (2),
+.BR select_tut (2),
+.BR timespec (3),
+.BR epoll (7),
+.BR time (7)
diff --git a/man/man2/posix_fadvise.2 b/man/man2/posix_fadvise.2
new file mode 100644
index 000000000..7984f7989
--- /dev/null
+++ b/man/man2/posix_fadvise.2
@@ -0,0 +1,227 @@
+.\" Copyright 2003 Abhijit Menon-Sen <ams@wiw.org>
+.\" and Copyright (C) 2010, 2015, 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2005-04-08 mtk, noted kernel version and added BUGS
+.\" 2010-10-09, mtk, document arm_fadvise64_64()
+.\"
+.TH posix_fadvise 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+posix_fadvise \- predeclare an access pattern for file data
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <fcntl.h>
+.P
+.BI "int posix_fadvise(int " fd ", off_t " offset ", off_t " len \
+", int " advice ");"
+.fi
+.P
+.ad l
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR posix_fadvise ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+Programs can use
+.BR posix_fadvise ()
+to announce an intention to access
+file data in a specific pattern in the future, thus allowing the kernel
+to perform appropriate optimizations.
+.P
+The \fIadvice\fP applies to a (not necessarily existent) region starting
+at \fIoffset\fP and extending for \fIlen\fP bytes (or until the end of
+the file if \fIlen\fP is 0) within the file referred to by \fIfd\fP.
+The \fIadvice\fP is not binding;
+it merely constitutes an expectation on behalf of
+the application.
+.P
+Permissible values for \fIadvice\fP include:
+.TP
+.B POSIX_FADV_NORMAL
+Indicates that the application has no advice to give about its access
+pattern for the specified data.
+If no advice is given for an open file,
+this is the default assumption.
+.TP
+.B POSIX_FADV_SEQUENTIAL
+The application expects to access the specified data sequentially (with
+lower offsets read before higher ones).
+.TP
+.B POSIX_FADV_RANDOM
+The specified data will be accessed in random order.
+.TP
+.B POSIX_FADV_NOREUSE
+The specified data will be accessed only once.
+.IP
+Before Linux 2.6.18, \fBPOSIX_FADV_NOREUSE\fP had the
+same semantics as \fBPOSIX_FADV_WILLNEED\fP.
+This was probably a bug; since Linux 2.6.18, this flag is a no-op.
+.TP
+.B POSIX_FADV_WILLNEED
+The specified data will be accessed in the near future.
+.IP
+\fBPOSIX_FADV_WILLNEED\fP initiates a
+nonblocking read of the specified region into the page cache.
+The amount of data read may be decreased by the kernel depending
+on virtual memory load.
+(A few megabytes will usually be fully satisfied,
+and more is rarely useful.)
+.TP
+.B POSIX_FADV_DONTNEED
+The specified data will not be accessed in the near future.
+.IP
+\fBPOSIX_FADV_DONTNEED\fP attempts to free cached pages associated with
+the specified region.
+This is useful, for example, while streaming large
+files.
+A program may periodically request the kernel to free cached data
+that has already been used, so that more useful cached pages are not
+discarded instead.
+.IP
+Requests to discard partial pages are ignored.
+It is preferable to preserve needed data than discard unneeded data.
+If the application requires that data be considered for discarding, then
+.I offset
+and
+.I len
+must be page-aligned.
+.IP
+The implementation
+.I may
+attempt to write back dirty pages in the specified region,
+but this is not guaranteed.
+Any unwritten dirty pages will not be freed.
+If the application wishes to ensure that dirty pages will be released,
+it should call
+.BR fsync (2)
+or
+.BR fdatasync (2)
+first.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, an error number is returned.
+.SH ERRORS
+.TP
+.B EBADF
+The \fIfd\fP argument was not a valid file descriptor.
+.TP
+.B EINVAL
+An invalid value was specified for \fIadvice\fP.
+.TP
+.B ESPIPE
+The specified file descriptor refers to a pipe or FIFO.
+.RB ( ESPIPE
+is the error specified by POSIX,
+but before Linux 2.6.16,
+.\" commit 87ba81dba431232548ce29d5d224115d0c2355ac
+Linux returned
+.B EINVAL
+in this case.)
+.SH VERSIONS
+Under Linux, \fBPOSIX_FADV_NORMAL\fP sets the readahead window to the
+default size for the backing device; \fBPOSIX_FADV_SEQUENTIAL\fP doubles
+this size, and \fBPOSIX_FADV_RANDOM\fP disables file readahead entirely.
+These changes affect the entire file, not just the specified region
+(but other open file handles to the same file are unaffected).
+.SS C library/kernel differences
+The name of the wrapper function in the C library is
+.BR posix_fadvise ().
+The underlying system call is called
+.BR fadvise64 ()
+(or, on some architectures,
+.BR fadvise64_64 ());
+the difference between the two is that the former system call
+assumes that the type of the \fIlen\fP argument is \fIsize_t\fP,
+while the latter expects \fIloff_t\fP there.
+.SS Architecture-specific variants
+Some architectures require
+64-bit arguments to be aligned in a suitable pair of registers (see
+.BR syscall (2)
+for further detail).
+On such architectures, the call signature of
+.BR posix_fadvise ()
+shown in the SYNOPSIS would force
+a register to be wasted as padding between the
+.I fd
+and
+.I offset
+arguments.
+Therefore, these architectures define a version of the
+system call that orders the arguments suitably,
+but is otherwise exactly the same as
+.BR posix_fadvise ().
+.P
+For example, since Linux 2.6.14, ARM has the following system call:
+.P
+.in +4n
+.EX
+.BI "long arm_fadvise64_64(int " fd ", int " advice ,
+.BI "                      loff_t " offset ", loff_t " len );
+.EE
+.in
+.P
+These architecture-specific details are generally
+hidden from applications by the glibc
+.BR posix_fadvise ()
+wrapper function,
+which invokes the appropriate architecture-specific system call.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Kernel support first appeared in Linux 2.5.60;
+the underlying system call is called
+.BR fadvise64 ().
+.\" of fadvise64_64()
+Library support has been provided since glibc 2.2,
+via the wrapper function
+.BR posix_fadvise ().
+.P
+Since Linux 3.18,
+.\" commit d3ac21cacc24790eb45d735769f35753f5b56ceb
+support for the underlying system call is optional,
+depending on the setting of the
+.B CONFIG_ADVISE_SYSCALLS
+configuration option.
+.P
+The type of the
+.I len
+argument was changed from
+.I size_t
+to
+.I off_t
+in POSIX.1-2001 TC1.
+.SH NOTES
+The contents of the kernel buffer cache can be cleared via the
+.I /proc/sys/vm/drop_caches
+interface described in
+.BR proc (5).
+.P
+One can obtain a snapshot of which pages of a file are resident
+in the buffer cache by opening a file, mapping it with
+.BR mmap (2),
+and then applying
+.BR mincore (2)
+to the mapping.
+.SH BUGS
+Before Linux 2.6.6, if
+.I len
+was specified as 0, then this was interpreted literally as "zero bytes",
+rather than as meaning "all bytes through to the end of the file".
+.SH SEE ALSO
+.BR fincore (1),
+.BR mincore (2),
+.BR readahead (2),
+.BR sync_file_range (2),
+.BR posix_fallocate (3),
+.BR posix_madvise (3)
diff --git a/man/man2/ppoll.2 b/man/man2/ppoll.2
new file mode 100644
index 000000000..227cd0e47
--- /dev/null
+++ b/man/man2/ppoll.2
@@ -0,0 +1 @@
+.so man2/poll.2
diff --git a/man/man2/prctl.2 b/man/man2/prctl.2
new file mode 100644
index 000000000..fad855832
--- /dev/null
+++ b/man/man2/prctl.2
@@ -0,0 +1,2577 @@
+.\" Copyright (C) 1998 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (C) 2002, 2006, 2008, 2012, 2013, 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright Guillem Jover <guillem@hadrons.org>
+.\" and Copyright (C) 2010 Andi Kleen <andi@firstfloor.org>
+.\" and Copyright (C) 2012 Cyrill Gorcunov <gorcunov@openvz.org>
+.\" and Copyright (C) 2014 Dave Hansen / Intel
+.\" and Copyright (c) 2016 Eugene Syromyatnikov <evgsyr@gmail.com>
+.\" and Copyright (c) 2018 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+.\" and Copyright (c) 2020 Dave Martin <Dave.Martin@arm.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Thu Nov 11 04:19:42 MET 1999, aeb: added PR_GET_PDEATHSIG
+.\" Modified 27 Jun 02, Michael Kerrisk
+.\" 	Added PR_SET_DUMPABLE, PR_GET_DUMPABLE,
+.\"	PR_SET_KEEPCAPS, PR_GET_KEEPCAPS
+.\" Modified 2006-08-30 Guillem Jover <guillem@hadrons.org>
+.\"	Updated Linux versions where the options where introduced.
+.\"	Added PR_SET_TIMING, PR_GET_TIMING, PR_SET_NAME, PR_GET_NAME,
+.\"	PR_SET_UNALIGN, PR_GET_UNALIGN, PR_SET_FPEMU, PR_GET_FPEMU,
+.\"	PR_SET_FPEXC, PR_GET_FPEXC
+.\" 2008-04-29 Serge Hallyn, Document PR_CAPBSET_READ and PR_CAPBSET_DROP
+.\" 2008-06-13 Erik Bosman, <ejbosman@cs.vu.nl>
+.\"     Document PR_GET_TSC and PR_SET_TSC.
+.\" 2008-06-15 mtk, Document PR_SET_SECCOMP, PR_GET_SECCOMP
+.\" 2009-10-03 Andi Kleen, document PR_MCE_KILL
+.\" 2012-04 Cyrill Gorcunov, Document PR_SET_MM
+.\" 2012-04-25 Michael Kerrisk, Document PR_TASK_PERF_EVENTS_DISABLE and
+.\"				PR_TASK_PERF_EVENTS_ENABLE
+.\" 2012-09-20 Kees Cook, update PR_SET_SECCOMP for mode 2
+.\" 2012-09-20 Kees Cook, document PR_SET_NO_NEW_PRIVS, PR_GET_NO_NEW_PRIVS
+.\" 2012-10-25 Michael Kerrisk, Document PR_SET_TIMERSLACK and
+.\"                             PR_GET_TIMERSLACK
+.\" 2013-01-10 Kees Cook, document PR_SET_PTRACER
+.\" 2012-02-04 Michael Kerrisk, document PR_{SET,GET}_CHILD_SUBREAPER
+.\" 2014-11-10 Dave Hansen, document PR_MPX_{EN,DIS}ABLE_MANAGEMENT
+.\"
+.\"
+.TH prctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+prctl \- operations on a process or thread
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/prctl.h>
+.P
+.BI "int prctl(int " op ", ..."
+.BI "          \fR/*\fP unsigned long " arg2 ", unsigned long " arg3 ,
+.BI "          unsigned long " arg4 ", unsigned long " arg5 " \fR*/\fP );"
+.fi
+.SH DESCRIPTION
+.BR prctl ()
+manipulates various aspects of the behavior
+of the calling thread or process.
+.P
+Note that careless use of some
+.BR prctl ()
+operations can confuse the user-space run-time environment,
+so these operations should be used with care.
+.P
+.BR prctl ()
+is called with a first argument describing what to do
+(with values defined in \fI<linux/prctl.h>\fP), and further
+arguments with a significance depending on the first one.
+The first argument can be:
+.\"
+.\" prctl PR_CAP_AMBIENT
+.TP
+.BR PR_CAP_AMBIENT " (since Linux 4.3)"
+.\" commit 58319057b7847667f0c9585b9de0e8932b0fdb08
+Reads or changes the ambient capability set of the calling thread,
+according to the value of
+.IR arg2 ,
+which must be one of the following:
+.RS
+.\"
+.TP
+.B PR_CAP_AMBIENT_RAISE
+The capability specified in
+.I arg3
+is added to the ambient set.
+The specified capability must already be present in
+both the permitted and the inheritable sets of the process.
+This operation is not permitted if the
+.B SECBIT_NO_CAP_AMBIENT_RAISE
+securebit is set.
+.TP
+.B PR_CAP_AMBIENT_LOWER
+The capability specified in
+.I arg3
+is removed from the ambient set.
+.TP
+.B PR_CAP_AMBIENT_IS_SET
+The
+.BR prctl ()
+call returns 1 if the capability in
+.I arg3
+is in the ambient set and 0 if it is not.
+.TP
+.B PR_CAP_AMBIENT_CLEAR_ALL
+All capabilities will be removed from the ambient set.
+This operation requires setting
+.I arg3
+to zero.
+.RE
+.IP
+In all of the above operations,
+.I arg4
+and
+.I arg5
+must be specified as 0.
+.IP
+Higher-level interfaces layered on top of the above operations are
+provided in the
+.BR libcap (3)
+library in the form of
+.BR cap_get_ambient (3),
+.BR cap_set_ambient (3),
+and
+.BR cap_reset_ambient (3).
+.\" prctl PR_CAPBSET_READ
+.TP
+.BR PR_CAPBSET_READ " (since Linux 2.6.25)"
+Return (as the function result) 1 if the capability specified in
+.I arg2
+is in the calling thread's capability bounding set,
+or 0 if it is not.
+(The capability constants are defined in
+.IR <linux/capability.h> .)
+The capability bounding set dictates
+whether the process can receive the capability through a
+file's permitted capability set on a subsequent call to
+.BR execve (2).
+.IP
+If the capability specified in
+.I arg2
+is not valid, then the call fails with the error
+.BR EINVAL .
+.IP
+A higher-level interface layered on top of this operation is provided in the
+.BR libcap (3)
+library in the form of
+.BR cap_get_bound (3).
+.\" prctl PR_CAPBSET_DROP
+.TP
+.BR PR_CAPBSET_DROP " (since Linux 2.6.25)"
+If the calling thread has the
+.B CAP_SETPCAP
+capability within its user namespace, then drop the capability specified by
+.I arg2
+from the calling thread's capability bounding set.
+Any children of the calling thread will inherit the newly
+reduced bounding set.
+.IP
+The call fails with the error:
+.B EPERM
+if the calling thread does not have the
+.BR CAP_SETPCAP ;
+.B EINVAL
+if
+.I arg2
+does not represent a valid capability; or
+.B EINVAL
+if file capabilities are not enabled in the kernel,
+in which case bounding sets are not supported.
+.IP
+A higher-level interface layered on top of this operation is provided in the
+.BR libcap (3)
+library in the form of
+.BR cap_drop_bound (3).
+.\" prctl PR_SET_CHILD_SUBREAPER
+.TP
+.BR PR_SET_CHILD_SUBREAPER " (since Linux 3.4)"
+.\" commit ebec18a6d3aa1e7d84aab16225e87fd25170ec2b
+If
+.I arg2
+is nonzero,
+set the "child subreaper" attribute of the calling process;
+if
+.I arg2
+is zero, unset the attribute.
+.IP
+A subreaper fulfills the role of
+.BR init (1)
+for its descendant processes.
+When a process becomes orphaned
+(i.e., its immediate parent terminates),
+then that process will be reparented to
+the nearest still living ancestor subreaper.
+Subsequently, calls to
+.BR getppid (2)
+in the orphaned process will now return the PID of the subreaper process,
+and when the orphan terminates, it is the subreaper process that
+will receive a
+.B SIGCHLD
+signal and will be able to
+.BR wait (2)
+on the process to discover its termination status.
+.IP
+The setting of the "child subreaper" attribute
+is not inherited by children created by
+.BR fork (2)
+and
+.BR clone (2).
+The setting is preserved across
+.BR execve (2).
+.IP
+Establishing a subreaper process is useful in session management frameworks
+where a hierarchical group of processes is managed by a subreaper process
+that needs to be informed when one of the processes\[em]for example,
+a double-forked daemon\[em]terminates
+(perhaps so that it can restart that process).
+Some
+.BR init (1)
+frameworks (e.g.,
+.BR systemd (1))
+employ a subreaper process for similar reasons.
+.\" prctl PR_GET_CHILD_SUBREAPER
+.TP
+.BR PR_GET_CHILD_SUBREAPER " (since Linux 3.4)"
+Return the "child subreaper" setting of the caller,
+in the location pointed to by
+.IR "(int\~*) arg2" .
+.\" prctl PR_SET_DUMPABLE
+.TP
+.BR PR_SET_DUMPABLE " (since Linux 2.3.20)"
+Set the state of the "dumpable" attribute,
+which determines whether core dumps are produced for the calling process
+upon delivery of a signal whose default behavior is to produce a core dump.
+.IP
+Up to and including Linux 2.6.12,
+.I arg2
+must be either 0
+.RB ( SUID_DUMP_DISABLE ,
+process is not dumpable) or 1
+.RB ( SUID_DUMP_USER ,
+process is dumpable).
+Between Linux 2.6.13 and Linux 2.6.17,
+.\" commit abf75a5033d4da7b8a7e92321d74021d1fcfb502
+the value 2 was also permitted,
+which caused any binary which normally would not be dumped
+to be dumped readable by root only;
+for security reasons, this feature has been removed.
+.\" See http://marc.theaimsgroup.com/?l=linux-kernel&m=115270289030630&w=2
+.\" Subject:    Fix prctl privilege escalation (CVE-2006-2451)
+.\" From:       Marcel Holtmann <marcel () holtmann ! org>
+.\" Date:       2006-07-12 11:12:00
+(See also the description of
+.I /proc/sys/fs/\:suid_dumpable
+in
+.BR proc (5).)
+.IP
+Normally, the "dumpable" attribute is set to 1.
+However, it is reset to the current value contained in the file
+.I /proc/sys/fs/\:suid_dumpable
+(which by default has the value 0),
+in the following circumstances:
+.\" See kernel/cred.c::commit_creds() (Linux 3.18 sources)
+.RS
+.IP \[bu] 3
+The process's effective user or group ID is changed.
+.IP \[bu]
+The process's filesystem user or group ID is changed (see
+.BR credentials (7)).
+.IP \[bu]
+The process executes
+.RB ( execve (2))
+a set-user-ID or set-group-ID program, resulting in a change
+of either the effective user ID or the effective group ID.
+.IP \[bu]
+The process executes
+.RB ( execve (2))
+a program that has file capabilities (see
+.BR capabilities (7)),
+.\" See kernel/cred.c::commit_creds()
+but only if the permitted capabilities
+gained exceed those already permitted for the process.
+.\" Also certain namespace operations;
+.RE
+.IP
+Processes that are not dumpable can not be attached via
+.BR ptrace (2)
+.BR PTRACE_ATTACH ;
+see
+.BR ptrace (2)
+for further details.
+.IP
+If a process is not dumpable,
+the ownership of files in the process's
+.IR /proc/ pid
+directory is affected as described in
+.BR proc (5).
+.\" prctl PR_GET_DUMPABLE
+.TP
+.BR PR_GET_DUMPABLE " (since Linux 2.3.20)"
+Return (as the function result) the current state of the calling
+process's dumpable attribute.
+.\" Since Linux 2.6.13, the dumpable flag can have the value 2,
+.\" but in Linux 2.6.13 PR_GET_DUMPABLE simply returns 1 if the dumpable
+.\" flags has a nonzero value.  This was fixed in Linux 2.6.14.
+.\" prctl PR_SET_ENDIAN
+.TP
+.BR PR_SET_ENDIAN " (since Linux 2.6.18, PowerPC only)"
+Set the endian-ness of the calling process to the value given
+in \fIarg2\fP, which should be one of the following:
+.\" Respectively 0, 1, 2
+.BR PR_ENDIAN_BIG ,
+.BR PR_ENDIAN_LITTLE ,
+or
+.B PR_ENDIAN_PPC_LITTLE
+(PowerPC pseudo little endian).
+.\" prctl PR_GET_ENDIAN
+.TP
+.BR PR_GET_ENDIAN " (since Linux 2.6.18, PowerPC only)"
+Return the endian-ness of the calling process,
+in the location pointed to by
+.IR "(int\~*) arg2" .
+.\" prctl PR_SET_FP_MODE
+.TP
+.BR PR_SET_FP_MODE " (since Linux 4.0, only on MIPS)"
+.\" commit 9791554b45a2acc28247f66a5fd5bbc212a6b8c8
+On the MIPS architecture,
+user-space code can be built using an ABI which permits linking
+with code that has more restrictive floating-point (FP) requirements.
+For example, user-space code may be built to target the O32 FPXX ABI
+and linked with code built for either one of the more restrictive
+FP32 or FP64 ABIs.
+When more restrictive code is linked in,
+the overall requirement for the process is to use the more
+restrictive floating-point mode.
+.IP
+Because the kernel has no means of knowing in advance
+which mode the process should be executed in,
+and because these restrictions can
+change over the lifetime of the process, the
+.B PR_SET_FP_MODE
+operation is provided to allow control of the floating-point mode
+from user space.
+.IP
+.\" https://dmz-portal.mips.com/wiki/MIPS_O32_ABI_-_FR0_and_FR1_Interlinking
+The
+.I (unsigned int) arg2
+argument is a bit mask describing the floating-point mode used:
+.RS
+.TP
+.B PR_FP_MODE_FR
+When this bit is
+.I unset
+(so called
+.BR FR=0 " or " FR0
+mode), the 32 floating-point registers are 32 bits wide,
+and 64-bit registers are represented as a pair of registers
+(even- and odd- numbered,
+with the even-numbered register containing the lower 32 bits,
+and the odd-numbered register containing the higher 32 bits).
+.IP
+When this bit is
+.I set
+(on supported hardware),
+the 32 floating-point registers are 64 bits wide (so called
+.BR FR=1 " or " FR1
+mode).
+Note that modern MIPS implementations (MIPS R6 and newer) support
+.B FR=1
+mode only.
+.IP
+Applications that use the O32 FP32 ABI can operate only when this bit is
+.I unset
+.RB ( FR=0 ;
+or they can be used with FRE enabled, see below).
+Applications that use the O32 FP64 ABI
+(and the O32 FP64A ABI, which exists to
+provide the ability to operate with existing FP32 code; see below)
+can operate only when this bit is
+.I set
+.RB ( FR=1 ).
+Applications that use the O32 FPXX ABI can operate with either
+.B FR=0
+or
+.BR FR=1 .
+.TP
+.B PR_FP_MODE_FRE
+Enable emulation of 32-bit floating-point mode.
+When this mode is enabled,
+it emulates 32-bit floating-point operations
+by raising a reserved-instruction exception
+on every instruction that uses 32-bit formats and
+the kernel then handles the instruction in software.
+(The problem lies in the discrepancy of handling odd-numbered registers
+which are the high 32 bits of 64-bit registers with even numbers in
+.B FR=0
+mode and the lower 32-bit parts of odd-numbered 64-bit registers in
+.B FR=1
+mode.)
+Enabling this bit is necessary when code with the O32 FP32 ABI should operate
+with code with compatible the O32 FPXX or O32 FP64A ABIs (which require
+.B FR=1
+FPU mode) or when it is executed on newer hardware (MIPS R6 onwards)
+which lacks
+.B FR=0
+mode support when a binary with the FP32 ABI is used.
+.IP
+Note that this mode makes sense only when the FPU is in 64-bit mode
+.RB ( FR=1 ).
+.IP
+Note that the use of emulation inherently has a significant performance hit
+and should be avoided if possible.
+.RE
+.IP
+In the N32/N64 ABI, 64-bit floating-point mode is always used,
+so FPU emulation is not required and the FPU always operates in
+.B FR=1
+mode.
+.IP
+This operation is mainly intended for use by the dynamic linker
+.RB ( ld.so (8)).
+.IP
+The arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.\" prctl PR_GET_FP_MODE
+.TP
+.BR PR_GET_FP_MODE " (since Linux 4.0, only on MIPS)"
+Return (as the function result)
+the current floating-point mode (see the description of
+.B PR_SET_FP_MODE
+for details).
+.IP
+On success,
+the call returns a bit mask which represents the current floating-point mode.
+.IP
+The arguments
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.\" prctl PR_SET_FPEMU
+.TP
+.BR PR_SET_FPEMU " (since Linux 2.4.18, 2.5.9, only on ia64)"
+Set floating-point emulation control bits to \fIarg2\fP.
+Pass
+.B PR_FPEMU_NOPRINT
+to silently emulate floating-point operation accesses, or
+.B PR_FPEMU_SIGFPE
+to not emulate floating-point operations and send
+.B SIGFPE
+instead.
+.\" prctl PR_GET_FPEMU
+.TP
+.BR PR_GET_FPEMU " (since Linux 2.4.18, 2.5.9, only on ia64)"
+Return floating-point emulation control bits,
+in the location pointed to by
+.IR "(int\~*) arg2" .
+.\" prctl PR_SET_FPEXC
+.TP
+.BR PR_SET_FPEXC " (since Linux 2.4.21, 2.5.32, only on PowerPC)"
+Set floating-point exception mode to \fIarg2\fP.
+Pass \fBPR_FP_EXC_SW_ENABLE\fP to use FPEXC for FP exception enables,
+\fBPR_FP_EXC_DIV\fP for floating-point divide by zero,
+\fBPR_FP_EXC_OVF\fP for floating-point overflow,
+\fBPR_FP_EXC_UND\fP for floating-point underflow,
+\fBPR_FP_EXC_RES\fP for floating-point inexact result,
+\fBPR_FP_EXC_INV\fP for floating-point invalid operation,
+\fBPR_FP_EXC_DISABLED\fP for FP exceptions disabled,
+\fBPR_FP_EXC_NONRECOV\fP for async nonrecoverable exception mode,
+\fBPR_FP_EXC_ASYNC\fP for async recoverable exception mode,
+\fBPR_FP_EXC_PRECISE\fP for precise exception mode.
+.\" prctl PR_GET_FPEXC
+.TP
+.BR PR_GET_FPEXC " (since Linux 2.4.21, 2.5.32, only on PowerPC)"
+Return floating-point exception mode,
+in the location pointed to by
+.IR "(int\~*) arg2" .
+.\" prctl PR_SET_IO_FLUSHER
+.TP
+.BR PR_SET_IO_FLUSHER " (since Linux 5.6)"
+If a user process is involved in the block layer or filesystem I/O path,
+and can allocate memory while processing I/O requests it must set
+\fIarg2\fP to 1.
+This will put the process in the IO_FLUSHER state,
+which allows it special treatment to make progress when allocating memory.
+If \fIarg2\fP is 0, the process will clear the IO_FLUSHER state, and
+the default behavior will be used.
+.IP
+The calling process must have the
+.B CAP_SYS_RESOURCE
+capability.
+.IP
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+must be zero.
+.IP
+The IO_FLUSHER state is inherited by a child process created via
+.BR fork (2)
+and is preserved across
+.BR execve (2).
+.IP
+Examples of IO_FLUSHER applications are FUSE daemons, SCSI device
+emulation daemons, and daemons that perform error handling like multipath
+path recovery applications.
+.\" prctl PR_GET_IO_FLUSHER
+.TP
+.B PR_GET_IO_FLUSHER (Since Linux 5.6)
+Return (as the function result) the IO_FLUSHER state of the caller.
+A value of 1 indicates that the caller is in the IO_FLUSHER state;
+0 indicates that the caller is not in the IO_FLUSHER state.
+.IP
+The calling process must have the
+.B CAP_SYS_RESOURCE
+capability.
+.IP
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+must be zero.
+.\" prctl PR_SET_KEEPCAPS
+.TP
+.BR PR_SET_KEEPCAPS " (since Linux 2.2.18)"
+Set the state of the calling thread's "keep capabilities" flag.
+The effect of this flag is described in
+.BR capabilities (7).
+.I arg2
+must be either 0 (clear the flag)
+or 1 (set the flag).
+The "keep capabilities" value will be reset to 0 on subsequent calls to
+.BR execve (2).
+.\" prctl PR_GET_KEEPCAPS
+.TP
+.BR PR_GET_KEEPCAPS " (since Linux 2.2.18)"
+Return (as the function result) the current state of the calling thread's
+"keep capabilities" flag.
+See
+.BR capabilities (7)
+for a description of this flag.
+.\" prctl PR_MCE_KILL
+.TP
+.BR PR_MCE_KILL " (since Linux 2.6.32)"
+Set the machine check memory corruption kill policy for the calling thread.
+If
+.I arg2
+is
+.BR PR_MCE_KILL_CLEAR ,
+clear the thread memory corruption kill policy and use the system-wide default.
+(The system-wide default is defined by
+.IR /proc/sys/vm/memory_failure_early_kill ;
+see
+.BR proc (5).)
+If
+.I arg2
+is
+.BR PR_MCE_KILL_SET ,
+use a thread-specific memory corruption kill policy.
+In this case,
+.I arg3
+defines whether the policy is
+.I early kill
+.RB ( PR_MCE_KILL_EARLY ),
+.I late kill
+.RB ( PR_MCE_KILL_LATE ),
+or the system-wide default
+.RB ( PR_MCE_KILL_DEFAULT ).
+Early kill means that the thread receives a
+.B SIGBUS
+signal as soon as hardware memory corruption is detected inside
+its address space.
+In late kill mode, the process is killed only when it accesses a corrupted page.
+See
+.BR sigaction (2)
+for more information on the
+.B SIGBUS
+signal.
+The policy is inherited by children.
+The remaining unused
+.BR prctl ()
+arguments must be zero for future compatibility.
+.\" prctl PR_MCE_KILL_GET
+.TP
+.BR PR_MCE_KILL_GET " (since Linux 2.6.32)"
+Return (as the function result)
+the current per-process machine check kill policy.
+All unused
+.BR prctl ()
+arguments must be zero.
+.\" prctl PR_SET_MM
+.TP
+.BR PR_SET_MM " (since Linux 3.3)"
+.\" commit 028ee4be34a09a6d48bdf30ab991ae933a7bc036
+Modify certain kernel memory map descriptor fields
+of the calling process.
+Usually these fields are set by the kernel and dynamic loader (see
+.BR ld.so (8)
+for more information) and a regular application should not use this feature.
+However, there are cases, such as self-modifying programs,
+where a program might find it useful to change its own memory map.
+.IP
+The calling process must have the
+.B CAP_SYS_RESOURCE
+capability.
+The value in
+.I arg2
+is one of the options below, while
+.I arg3
+provides a new value for the option.
+The
+.I arg4
+and
+.I arg5
+arguments must be zero if unused.
+.IP
+Before Linux 3.10,
+.\" commit 52b3694157e3aa6df871e283115652ec6f2d31e0
+this feature is available only if the kernel is built with the
+.B CONFIG_CHECKPOINT_RESTORE
+option enabled.
+.RS
+.TP
+.B PR_SET_MM_START_CODE
+Set the address above which the program text can run.
+The corresponding memory area must be readable and executable,
+but not writable or shareable (see
+.BR mprotect (2)
+and
+.BR mmap (2)
+for more information).
+.TP
+.B PR_SET_MM_END_CODE
+Set the address below which the program text can run.
+The corresponding memory area must be readable and executable,
+but not writable or shareable.
+.TP
+.B PR_SET_MM_START_DATA
+Set the address above which initialized and
+uninitialized (bss) data are placed.
+The corresponding memory area must be readable and writable,
+but not executable or shareable.
+.TP
+.B PR_SET_MM_END_DATA
+Set the address below which initialized and
+uninitialized (bss) data are placed.
+The corresponding memory area must be readable and writable,
+but not executable or shareable.
+.TP
+.B PR_SET_MM_START_STACK
+Set the start address of the stack.
+The corresponding memory area must be readable and writable.
+.TP
+.B PR_SET_MM_START_BRK
+Set the address above which the program heap can be expanded with
+.BR brk (2)
+call.
+The address must be greater than the ending address of
+the current program data segment.
+In addition, the combined size of the resulting heap and
+the size of the data segment can't exceed the
+.B RLIMIT_DATA
+resource limit (see
+.BR setrlimit (2)).
+.TP
+.B PR_SET_MM_BRK
+Set the current
+.BR brk (2)
+value.
+The requirements for the address are the same as for the
+.B PR_SET_MM_START_BRK
+option.
+.P
+The following options are available since Linux 3.5.
+.\" commit fe8c7f5cbf91124987106faa3bdf0c8b955c4cf7
+.TP
+.B PR_SET_MM_ARG_START
+Set the address above which the program command line is placed.
+.TP
+.B PR_SET_MM_ARG_END
+Set the address below which the program command line is placed.
+.TP
+.B PR_SET_MM_ENV_START
+Set the address above which the program environment is placed.
+.TP
+.B PR_SET_MM_ENV_END
+Set the address below which the program environment is placed.
+.IP
+The address passed with
+.BR PR_SET_MM_ARG_START ,
+.BR PR_SET_MM_ARG_END ,
+.BR PR_SET_MM_ENV_START ,
+and
+.B PR_SET_MM_ENV_END
+should belong to a process stack area.
+Thus, the corresponding memory area must be readable, writable, and
+(depending on the kernel configuration) have the
+.B MAP_GROWSDOWN
+attribute set (see
+.BR mmap (2)).
+.TP
+.B PR_SET_MM_AUXV
+Set a new auxiliary vector.
+The
+.I arg3
+argument should provide the address of the vector.
+The
+.I arg4
+is the size of the vector.
+.TP
+.B PR_SET_MM_EXE_FILE
+.\" commit b32dfe377102ce668775f8b6b1461f7ad428f8b6
+Supersede the
+.IR /proc/ pid /exe
+symbolic link with a new one pointing to a new executable file
+identified by the file descriptor provided in
+.I arg3
+argument.
+The file descriptor should be obtained with a regular
+.BR open (2)
+call.
+.IP
+To change the symbolic link, one needs to unmap all existing
+executable memory areas, including those created by the kernel itself
+(for example the kernel usually creates at least one executable
+memory area for the ELF
+.I .text
+section).
+.IP
+In Linux 4.9 and earlier, the
+.\" commit 3fb4afd9a504c2386b8435028d43283216bf588e
+.B PR_SET_MM_EXE_FILE
+operation can be performed only once in a process's lifetime;
+attempting to perform the operation a second time results in the error
+.BR EPERM .
+This restriction was enforced for security reasons that were subsequently
+deemed specious,
+and the restriction was removed in Linux 4.10 because some
+user-space applications needed to perform this operation more than once.
+.P
+The following options are available since Linux 3.18.
+.\" commit f606b77f1a9e362451aca8f81d8f36a3a112139e
+.TP
+.B PR_SET_MM_MAP
+Provides one-shot access to all the addresses by passing in a
+.I struct prctl_mm_map
+(as defined in \fI<linux/prctl.h>\fP).
+The
+.I arg4
+argument should provide the size of the struct.
+.IP
+This feature is available only if the kernel is built with the
+.B CONFIG_CHECKPOINT_RESTORE
+option enabled.
+.TP
+.B PR_SET_MM_MAP_SIZE
+Returns the size of the
+.I struct prctl_mm_map
+the kernel expects.
+This allows user space to find a compatible struct.
+The
+.I arg4
+argument should be a pointer to an unsigned int.
+.IP
+This feature is available only if the kernel is built with the
+.B CONFIG_CHECKPOINT_RESTORE
+option enabled.
+.RE
+.\" prctl PR_SET_VMA
+.TP
+.BR PR_SET_VMA " (since Linux 5.17)"
+.\" Commit 9a10064f5625d5572c3626c1516e0bebc6c9fe9b
+Sets an attribute specified in
+.I arg2
+for virtual memory areas starting from the address specified in
+.I arg3
+and spanning the size specified in
+.IR arg4 .
+.I arg5
+specifies the value of the attribute to be set.
+.IP
+Note that assigning an attribute to a virtual memory area
+might prevent it from being merged with adjacent virtual memory areas
+due to the difference in that attribute's value.
+.IP
+Currently,
+.I arg2
+must be one of:
+.RS
+.TP
+.B PR_SET_VMA_ANON_NAME
+Set a name for anonymous virtual memory areas.
+.I arg5
+should be a pointer to a null-terminated string containing the name.
+The name length including null byte cannot exceed 80 bytes.
+If
+.I arg5
+is NULL, the name of the appropriate anonymous virtual memory areas
+will be reset.
+The name can contain only printable ascii characters (including space),
+except \[aq][\[aq], \[aq]]\[aq], \[aq]\e\[aq], \[aq]$\[aq], and \[aq]\[ga]\[aq].
+.RE
+.\" prctl PR_MPX_ENABLE_MANAGEMENT
+.TP
+.B PR_MPX_ENABLE_MANAGEMENT
+.TQ
+.BR PR_MPX_DISABLE_MANAGEMENT " (since Linux 3.19, removed in Linux 5.4; only on x86)"
+.\" commit fe3d197f84319d3bce379a9c0dc17b1f48ad358c
+.\" See also http://lwn.net/Articles/582712/
+.\" See also https://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler
+Enable or disable kernel management of Memory Protection eXtensions (MPX)
+bounds tables.
+The
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+.\" commit e9d1b4f3c60997fe197bf0243cb4a41a44387a88
+arguments must be zero.
+.IP
+MPX is a hardware-assisted mechanism for performing bounds checking on
+pointers.
+It consists of a set of registers storing bounds information
+and a set of special instruction prefixes that tell the CPU on which
+instructions it should do bounds enforcement.
+There is a limited number of these registers and
+when there are more pointers than registers,
+their contents must be "spilled" into a set of tables.
+These tables are called "bounds tables" and the MPX
+.BR prctl ()
+operations control
+whether the kernel manages their allocation and freeing.
+.IP
+When management is enabled, the kernel will take over allocation
+and freeing of the bounds tables.
+It does this by trapping the #BR exceptions that result
+at first use of missing bounds tables and
+instead of delivering the exception to user space,
+it allocates the table and populates the bounds directory
+with the location of the new table.
+For freeing, the kernel checks to see if bounds tables are
+present for memory which is not allocated, and frees them if so.
+.IP
+Before enabling MPX management using
+.BR PR_MPX_ENABLE_MANAGEMENT ,
+the application must first have allocated a user-space buffer for
+the bounds directory and placed the location of that directory in the
+.I bndcfgu
+register.
+.IP
+These calls fail if the CPU or kernel does not support MPX.
+Kernel support for MPX is enabled via the
+.B CONFIG_X86_INTEL_MPX
+configuration option.
+You can check whether the CPU supports MPX by looking for the
+.I mpx
+CPUID bit, like with the following command:
+.IP
+.in +4n
+.EX
+cat /proc/cpuinfo | grep \[aq] mpx \[aq]
+.EE
+.in
+.IP
+A thread may not switch in or out of long (64-bit) mode while MPX is
+enabled.
+.IP
+All threads in a process are affected by these calls.
+.IP
+The child of a
+.BR fork (2)
+inherits the state of MPX management.
+During
+.BR execve (2),
+MPX management is reset to a state as if
+.B PR_MPX_DISABLE_MANAGEMENT
+had been called.
+.IP
+For further information on Intel MPX, see the kernel source file
+.IR Documentation/x86/intel_mpx.txt .
+.IP
+.\" commit f240652b6032b48ad7fa35c5e701cc4c8d697c0b
+.\" See also https://lkml.kernel.org/r/20190705175321.DB42F0AD@viggo.jf.intel.com
+Due to a lack of toolchain support,
+.BR PR_MPX_ENABLE_MANAGEMENT " and " PR_MPX_DISABLE_MANAGEMENT
+are not supported in Linux 5.4 and later.
+.\" prctl PR_SET_NAME
+.TP
+.BR PR_SET_NAME " (since Linux 2.6.9)"
+Set the name of the calling thread,
+using the value in the location pointed to by
+.IR "(char\~*) arg2" .
+The name can be up to 16 bytes long,
+.\" TASK_COMM_LEN in include/linux/sched.h
+including the terminating null byte.
+(If the length of the string, including the terminating null byte,
+exceeds 16 bytes, the string is silently truncated.)
+This is the same attribute that can be set via
+.BR pthread_setname_np (3)
+and retrieved using
+.BR pthread_getname_np (3).
+The attribute is likewise accessible via
+.IR /proc/self/task/ tid /comm
+(see
+.BR proc (5)),
+where
+.I tid
+is the thread ID of the calling thread, as returned by
+.BR gettid (2).
+.\" prctl PR_GET_NAME
+.TP
+.BR PR_GET_NAME " (since Linux 2.6.11)"
+Return the name of the calling thread,
+in the buffer pointed to by
+.IR "(char\~*) arg2" .
+The buffer should allow space for up to 16 bytes;
+the returned string will be null-terminated.
+.\" prctl PR_SET_NO_NEW_PRIVS
+.TP
+.BR PR_SET_NO_NEW_PRIVS " (since Linux 3.5)"
+Set the calling thread's
+.I no_new_privs
+attribute to the value in
+.IR arg2 .
+With
+.I no_new_privs
+set to 1,
+.BR execve (2)
+promises not to grant privileges to do anything
+that could not have been done without the
+.BR execve (2)
+call (for example,
+rendering the set-user-ID and set-group-ID mode bits,
+and file capabilities non-functional).
+Once set, the
+.I no_new_privs
+attribute cannot be unset.
+The setting of this attribute is inherited by children created by
+.BR fork (2)
+and
+.BR clone (2),
+and preserved across
+.BR execve (2).
+.IP
+Since Linux 4.10,
+the value of a thread's
+.I no_new_privs
+attribute can be viewed via the
+.I NoNewPrivs
+field in the
+.IR /proc/ pid /status
+file.
+.IP
+For more information, see the kernel source file
+.I Documentation/userspace\-api/no_new_privs.rst
+.\" commit 40fde647ccb0ae8c11d256d271e24d385eed595b
+(or
+.I Documentation/prctl/no_new_privs.txt
+before Linux 4.13).
+See also
+.BR seccomp (2).
+.\" prctl PR_GET_NO_NEW_PRIVS
+.TP
+.BR PR_GET_NO_NEW_PRIVS " (since Linux 3.5)"
+Return (as the function result) the value of the
+.I no_new_privs
+attribute for the calling thread.
+A value of 0 indicates the regular
+.BR execve (2)
+behavior.
+A value of 1 indicates
+.BR execve (2)
+will operate in the privilege-restricting mode described above.
+.\" prctl PR_PAC_RESET_KEYS
+.\" commit ba830885656414101b2f8ca88786524d4bb5e8c1
+.TP
+.BR PR_PAC_RESET_KEYS " (since Linux 5.0, only on arm64)"
+Securely reset the thread's pointer authentication keys
+to fresh random values generated by the kernel.
+.IP
+The set of keys to be reset is specified by
+.IR arg2 ,
+which must be a logical OR of zero or more of the following:
+.RS
+.TP
+.B PR_PAC_APIAKEY
+instruction authentication key A
+.TP
+.B PR_PAC_APIBKEY
+instruction authentication key B
+.TP
+.B PR_PAC_APDAKEY
+data authentication key A
+.TP
+.B PR_PAC_APDBKEY
+data authentication key B
+.TP
+.B PR_PAC_APGAKEY
+generic authentication \[lq]A\[rq] key.
+.IP
+(Yes folks, there really is no generic B key.)
+.RE
+.IP
+As a special case, if
+.I arg2
+is zero, then all the keys are reset.
+Since new keys could be added in future,
+this is the recommended way to completely wipe the existing keys
+when establishing a clean execution context.
+Note that there is no need to use
+.B PR_PAC_RESET_KEYS
+in preparation for calling
+.BR execve (2),
+since
+.BR execve (2)
+resets all the pointer authentication keys.
+.IP
+The remaining arguments
+.IR arg3 ", " arg4 ", and " arg5
+must all be zero.
+.IP
+If the arguments are invalid,
+and in particular if
+.I arg2
+contains set bits that are unrecognized
+or that correspond to a key not available on this platform,
+then the call fails with error
+.BR EINVAL .
+.IP
+.B Warning:
+Because the compiler or run-time environment
+may be using some or all of the keys,
+a successful
+.B PR_PAC_RESET_KEYS
+may crash the calling process.
+The conditions for using it safely are complex and system-dependent.
+Don't use it unless you know what you are doing.
+.IP
+For more information, see the kernel source file
+.I Documentation/arm64/pointer\-authentication.rst
+.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed
+(or
+.I Documentation/arm64/pointer\-authentication.txt
+before Linux 5.3).
+.\" prctl PR_SET_PDEATHSIG
+.TP
+.BR PR_SET_PDEATHSIG " (since Linux 2.1.57)"
+Set the parent-death signal
+of the calling process to \fIarg2\fP (either a signal value
+in the range
+.RB [ 1 ,
+.IR NSIG\~\-\~1 ],
+or
+.B 0
+to clear).
+This is the signal that the calling process will get when its
+parent dies.
+.IP
+.IR Warning :
+.\" https://bugzilla.kernel.org/show_bug.cgi?id=43300
+the "parent" in this case is considered to be the
+.I thread
+that created this process.
+In other words, the signal will be sent when that thread terminates
+(via, for example,
+.BR pthread_exit (3)),
+rather than after all of the threads in the parent process terminate.
+.IP
+The parent-death signal is sent upon subsequent termination of the parent
+thread and also upon termination of each subreaper process
+(see the description of
+.B PR_SET_CHILD_SUBREAPER
+above) to which the caller is subsequently reparented.
+If the parent thread and all ancestor subreapers have already terminated
+by the time of the
+.B PR_SET_PDEATHSIG
+operation, then no parent-death signal is sent to the caller.
+.IP
+The parent-death signal is process-directed (see
+.BR signal (7))
+and, if the child installs a handler using the
+.BR sigaction (2)
+.B SA_SIGINFO
+flag, the
+.I si_pid
+field of the
+.I siginfo_t
+argument of the handler contains the PID of the terminating parent process.
+.IP
+The parent-death signal setting is cleared for the child of a
+.BR fork (2).
+It is also
+(since Linux 2.4.36 / 2.6.23)
+.\" commit d2d56c5f51028cb9f3d800882eb6f4cbd3f9099f
+cleared when executing a set-user-ID or set-group-ID binary,
+or a binary that has associated capabilities (see
+.BR capabilities (7));
+otherwise, this value is preserved across
+.BR execve (2).
+The parent-death signal setting is also cleared upon changes to
+any of the following thread credentials:
+.\" FIXME capability changes can also trigger this; see
+.\" kernel/cred.c::commit_creds in the Linux 5.6 source.
+effective user ID, effective group ID, filesystem user ID,
+or filesystem group ID.
+.\" prctl PR_GET_PDEATHSIG
+.TP
+.BR PR_GET_PDEATHSIG " (since Linux 2.3.15)"
+Return the current value of the parent process death signal,
+in the location pointed to by
+.IR "(int\~*) arg2" .
+.\" prctl PR_SET_PTRACER
+.TP
+.BR PR_SET_PTRACER " (since Linux 3.4)"
+.\" commit 2d514487faf188938a4ee4fb3464eeecfbdcf8eb
+.\" commit bf06189e4d14641c0148bea16e9dd24943862215
+This is meaningful only when the Yama LSM is enabled and in mode 1
+("restricted ptrace", visible via
+.IR /proc/sys/kernel/yama/ptrace_scope ).
+When a "ptracer process ID" is passed in \fIarg2\fP,
+the caller is declaring that the ptracer process can
+.BR ptrace (2)
+the calling process as if it were a direct process ancestor.
+Each
+.B PR_SET_PTRACER
+operation replaces the previous "ptracer process ID".
+Employing
+.B PR_SET_PTRACER
+with
+.I arg2
+set to 0 clears the caller's "ptracer process ID".
+If
+.I arg2
+is
+.BR PR_SET_PTRACER_ANY ,
+the ptrace restrictions introduced by Yama are effectively disabled for the
+calling process.
+.IP
+For further information, see the kernel source file
+.I Documentation/admin\-guide/LSM/Yama.rst
+.\" commit 90bb766440f2147486a2acc3e793d7b8348b0c22
+(or
+.I Documentation/security/Yama.txt
+before Linux 4.13).
+.\" prctl PR_SET_SECCOMP
+.TP
+.BR PR_SET_SECCOMP " (since Linux 2.6.23)"
+.\" See http://thread.gmane.org/gmane.linux.kernel/542632
+.\" [PATCH 0 of 2] seccomp updates
+.\" andrea@cpushare.com
+Set the secure computing (seccomp) mode for the calling thread, to limit
+the available system calls.
+The more recent
+.BR seccomp (2)
+system call provides a superset of the functionality of
+.BR PR_SET_SECCOMP ,
+and is the preferred interface for new applications.
+.IP
+The seccomp mode is selected via
+.IR arg2 .
+(The seccomp constants are defined in
+.IR <linux/seccomp.h> .)
+The following values can be specified:
+.RS
+.TP
+.BR SECCOMP_MODE_STRICT " (since Linux 2.6.23)"
+See the description of
+.B SECCOMP_SET_MODE_STRICT
+in
+.BR seccomp (2).
+.IP
+This operation is available only
+if the kernel is configured with
+.B CONFIG_SECCOMP
+enabled.
+.TP
+.BR SECCOMP_MODE_FILTER " (since Linux 3.5)"
+The allowed system calls are defined by a pointer
+to a Berkeley Packet Filter passed in
+.IR arg3 .
+This argument is a pointer to
+.IR "struct sock_fprog" ;
+it can be designed to filter
+arbitrary system calls and system call arguments.
+See the description of
+.B SECCOMP_SET_MODE_FILTER
+in
+.BR seccomp (2).
+.IP
+This operation is available only
+if the kernel is configured with
+.B CONFIG_SECCOMP_FILTER
+enabled.
+.RE
+.IP
+For further details on seccomp filtering, see
+.BR seccomp (2).
+.\" prctl PR_GET_SECCOMP
+.TP
+.BR PR_GET_SECCOMP " (since Linux 2.6.23)"
+Return (as the function result)
+the secure computing mode of the calling thread.
+If the caller is not in secure computing mode, this operation returns 0;
+if the caller is in strict secure computing mode, then the
+.BR prctl ()
+call will cause a
+.B SIGKILL
+signal to be sent to the process.
+If the caller is in filter mode, and this system call is allowed by the
+seccomp filters, it returns 2; otherwise, the process is killed with a
+.B SIGKILL
+signal.
+.IP
+This operation is available only
+if the kernel is configured with
+.B CONFIG_SECCOMP
+enabled.
+.IP
+Since Linux 3.8, the
+.I Seccomp
+field of the
+.IR /proc/ pid /status
+file provides a method of obtaining the same information,
+without the risk that the process is killed; see
+.BR proc (5).
+.\" prctl PR_SET_SECUREBITS
+.TP
+.BR PR_SET_SECUREBITS " (since Linux 2.6.26)"
+Set the "securebits" flags of the calling thread to the value supplied in
+.IR arg2 .
+See
+.BR capabilities (7).
+.\" prctl PR_GET_SECUREBITS
+.TP
+.BR PR_GET_SECUREBITS " (since Linux 2.6.26)"
+Return (as the function result)
+the "securebits" flags of the calling thread.
+See
+.BR capabilities (7).
+.\" prctl PR_GET_SPECULATION_CTRL
+.TP
+.BR PR_GET_SPECULATION_CTRL " (since Linux 4.17)"
+Return (as the function result)
+the state of the speculation misfeature specified in
+.IR arg2 .
+Currently, the only permitted value for this argument is
+.B PR_SPEC_STORE_BYPASS
+(otherwise the call fails with the error
+.BR ENODEV ).
+.IP
+The return value uses bits 0-3 with the following meaning:
+.RS
+.TP
+.B PR_SPEC_PRCTL
+Mitigation can be controlled per thread by
+.BR PR_SET_SPECULATION_CTRL .
+.TP
+.B PR_SPEC_ENABLE
+The speculation feature is enabled, mitigation is disabled.
+.TP
+.B PR_SPEC_DISABLE
+The speculation feature is disabled, mitigation is enabled.
+.TP
+.B PR_SPEC_FORCE_DISABLE
+Same as
+.B PR_SPEC_DISABLE
+but cannot be undone.
+.TP
+.BR PR_SPEC_DISABLE_NOEXEC " (since Linux 5.1)"
+Same as
+.BR PR_SPEC_DISABLE ,
+but the state will be cleared on
+.BR execve (2).
+.RE
+.IP
+If all bits are 0,
+then the CPU is not affected by the speculation misfeature.
+.IP
+If
+.B PR_SPEC_PRCTL
+is set, then per-thread control of the mitigation is available.
+If not set,
+.BR prctl ()
+for the speculation misfeature will fail.
+.IP
+The
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+arguments must be specified as 0; otherwise the call fails with the error
+.BR EINVAL .
+.\" prctl PR_SET_SPECULATION_CTRL
+.TP
+.BR PR_SET_SPECULATION_CTRL " (since Linux 4.17)"
+.\" commit b617cfc858161140d69cc0b5cc211996b557a1c7
+.\" commit 356e4bfff2c5489e016fdb925adbf12a1e3950ee
+Sets the state of the speculation misfeature specified in
+.IR arg2 .
+The speculation-misfeature settings are per-thread attributes.
+.IP
+Currently,
+.I arg2
+must be one of:
+.RS
+.TP
+.B PR_SPEC_STORE_BYPASS
+Set the state of the speculative store bypass misfeature.
+.\" commit 9137bb27e60e554dab694eafa4cca241fa3a694f
+.TP
+.BR PR_SPEC_INDIRECT_BRANCH " (since Linux 4.20)"
+Set the state of the indirect branch speculation misfeature.
+.RE
+.IP
+If
+.I arg2
+does not have one of the above values,
+then the call fails with the error
+.BR ENODEV .
+.IP
+The
+.I arg3
+argument is used to hand in the control value,
+which is one of the following:
+.RS
+.TP
+.B PR_SPEC_ENABLE
+The speculation feature is enabled, mitigation is disabled.
+.TP
+.B PR_SPEC_DISABLE
+The speculation feature is disabled, mitigation is enabled.
+.TP
+.B PR_SPEC_FORCE_DISABLE
+Same as
+.BR PR_SPEC_DISABLE ,
+but cannot be undone.
+A subsequent
+.BR prctl (\c
+.IR arg2 ,
+.BR PR_SPEC_ENABLE )
+with the same value for
+.I arg2
+will fail with the error
+.BR EPERM .
+.\" commit 71368af9027f18fe5d1c6f372cfdff7e4bde8b48
+.TP
+.BR PR_SPEC_DISABLE_NOEXEC " (since Linux 5.1)"
+Same as
+.BR PR_SPEC_DISABLE ,
+but the state will be cleared on
+.BR execve (2).
+Currently only supported for
+.I arg2
+equal to
+.B PR_SPEC_STORE_BYPASS.
+.RE
+.IP
+Any unsupported value in
+.I arg3
+will result in the call failing with the error
+.BR ERANGE .
+.IP
+The
+.I arg4
+and
+.I arg5
+arguments must be specified as 0; otherwise the call fails with the error
+.BR EINVAL .
+.IP
+The speculation feature can also be controlled by the
+.B spec_store_bypass_disable
+boot parameter.
+This parameter may enforce a read-only policy which will result in the
+.BR prctl ()
+call failing with the error
+.BR ENXIO .
+For further details, see the kernel source file
+.IR Documentation/admin\-guide/kernel\-parameters.txt .
+.\" prctl PR_SVE_SET_VL
+.\" commit 2d2123bc7c7f843aa9db87720de159a049839862
+.\" linux-5.6/Documentation/arm64/sve.rst
+.TP
+.BR PR_SVE_SET_VL " (since Linux 4.15, only on arm64)"
+Configure the thread's SVE vector length,
+as specified by
+.IR "(int) arg2" .
+Arguments
+.IR arg3 ,
+.IR arg4 ,
+and
+.I arg5
+are ignored.
+.IP
+The bits of
+.I arg2
+corresponding to
+.B PR_SVE_VL_LEN_MASK
+must be set to the desired vector length in bytes.
+This is interpreted as an upper bound:
+the kernel will select the greatest available vector length
+that does not exceed the value specified.
+In particular, specifying
+.B SVE_VL_MAX
+(defined in
+.I <asm/sigcontext.h>)
+for the
+.B PR_SVE_VL_LEN_MASK
+bits requests the maximum supported vector length.
+.IP
+In addition, the other bits of
+.I arg2
+must be set to one of the following combinations of flags:
+.RS
+.TP
+.B 0
+Perform the change immediately.
+At the next
+.BR execve (2)
+in the thread,
+the vector length will be reset to the value configured in
+.IR /proc/sys/abi/sve_default_vector_length .
+.TP
+.B PR_SVE_VL_INHERIT
+Perform the change immediately.
+Subsequent
+.BR execve (2)
+calls will preserve the new vector length.
+.TP
+.B PR_SVE_SET_VL_ONEXEC
+Defer the change, so that it is performed at the next
+.BR execve (2)
+in the thread.
+Further
+.BR execve (2)
+calls will reset the vector length to the value configured in
+.IR /proc/sys/abi/sve_default_vector_length .
+.TP
+.B "PR_SVE_SET_VL_ONEXEC | PR_SVE_VL_INHERIT"
+Defer the change, so that it is performed at the next
+.BR execve (2)
+in the thread.
+Further
+.BR execve (2)
+calls will preserve the new vector length.
+.RE
+.IP
+In all cases,
+any previously pending deferred change is canceled.
+.IP
+The call fails with error
+.B EINVAL
+if SVE is not supported on the platform, if
+.I arg2
+is unrecognized or invalid, or the value in the bits of
+.I arg2
+corresponding to
+.B PR_SVE_VL_LEN_MASK
+is outside the range
+.BR SVE_VL_MIN .. SVE_VL_MAX
+or is not a multiple of 16.
+.IP
+On success,
+a nonnegative value is returned that describes the
+.I selected
+configuration.
+If
+.B PR_SVE_SET_VL_ONEXEC
+was included in
+.IR arg2 ,
+then the configuration described by the return value
+will take effect at the next
+.BR execve (2).
+Otherwise, the configuration is already in effect when the
+.B PR_SVE_SET_VL
+call returns.
+In either case, the value is encoded in the same way as the return value of
+.BR PR_SVE_GET_VL .
+Note that there is no explicit flag in the return value
+corresponding to
+.BR PR_SVE_SET_VL_ONEXEC .
+.IP
+The configuration (including any pending deferred change)
+is inherited across
+.BR fork (2)
+and
+.BR clone (2).
+.IP
+For more information, see the kernel source file
+.I Documentation/arm64/sve.rst
+.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed
+(or
+.I Documentation/arm64/sve.txt
+before Linux 5.3).
+.IP
+.B Warning:
+Because the compiler or run-time environment
+may be using SVE, using this call without the
+.B PR_SVE_SET_VL_ONEXEC
+flag may crash the calling process.
+The conditions for using it safely are complex and system-dependent.
+Don't use it unless you really know what you are doing.
+.\" prctl PR_SVE_GET_VL
+.TP
+.BR PR_SVE_GET_VL " (since Linux 4.15, only on arm64)"
+Get the thread's current SVE vector length configuration.
+.IP
+Arguments
+.IR arg2 ", " arg3 ", " arg4 ", and " arg5
+are ignored.
+.IP
+Provided that the kernel and platform support SVE,
+this operation always succeeds,
+returning a nonnegative value that describes the
+.I current
+configuration.
+The bits corresponding to
+.B PR_SVE_VL_LEN_MASK
+contain the currently configured vector length in bytes.
+The bit corresponding to
+.B PR_SVE_VL_INHERIT
+indicates whether the vector length will be inherited
+across
+.BR execve (2).
+.IP
+Note that there is no way to determine whether there is
+a pending vector length change that has not yet taken effect.
+.IP
+For more information, see the kernel source file
+.I Documentation/arm64/sve.rst
+.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed
+(or
+.I Documentation/arm64/sve.txt
+before Linux 5.3).
+.TP
+.\" prctl PR_SET_SYSCALL_USER_DISPATCH
+.\" commit 1446e1df9eb183fdf81c3f0715402f1d7595d4
+.BR PR_SET_SYSCALL_USER_DISPATCH " (since Linux 5.11, x86 only)"
+Configure the Syscall User Dispatch mechanism
+for the calling thread.
+This mechanism allows an application
+to selectively intercept system calls
+so that they can be handled within the application itself.
+Interception takes the form of a thread-directed
+.B SIGSYS
+signal that is delivered to the thread
+when it makes a system call.
+If intercepted,
+the system call is not executed by the kernel.
+.IP
+To enable this mechanism,
+.I arg2
+should be set to
+.BR PR_SYS_DISPATCH_ON .
+Once enabled, further system calls will be selectively intercepted,
+depending on a control variable provided by user space.
+In this case,
+.I arg3
+and
+.I arg4
+respectively identify the
+.I offset
+and
+.I length
+of a single contiguous memory region in the process address space
+from where system calls are always allowed to be executed,
+regardless of the control variable.
+(Typically, this area would include the area of memory
+containing the C library.)
+.IP
+.I arg5
+points to a char-sized variable
+that is a fast switch to allow/block system call execution
+without the overhead of doing another system call
+to re-configure Syscall User Dispatch.
+This control variable can either be set to
+.B SYSCALL_DISPATCH_FILTER_BLOCK
+to block system calls from executing
+or to
+.B SYSCALL_DISPATCH_FILTER_ALLOW
+to temporarily allow them to be executed.
+This value is checked by the kernel
+on every system call entry,
+and any unexpected value will raise
+an uncatchable
+.B SIGSYS
+at that time,
+killing the application.
+.IP
+When a system call is intercepted,
+the kernel sends a thread-directed
+.B SIGSYS
+signal to the triggering thread.
+Various fields will be set in the
+.I siginfo_t
+structure (see
+.BR sigaction (2))
+associated with the signal:
+.RS
+.IP \[bu] 3
+.I si_signo
+will contain
+.BR SIGSYS .
+.IP \[bu]
+.I si_call_addr
+will show the address of the system call instruction.
+.IP \[bu]
+.I si_syscall
+and
+.I si_arch
+will indicate which system call was attempted.
+.IP \[bu]
+.I si_code
+will contain
+.BR SYS_USER_DISPATCH .
+.IP \[bu]
+.I si_errno
+will be set to 0.
+.RE
+.IP
+The program counter will be as though the system call happened
+(i.e., the program counter will not point to the system call instruction).
+.IP
+When the signal handler returns to the kernel,
+the system call completes immediately
+and returns to the calling thread,
+without actually being executed.
+If necessary
+(i.e., when emulating the system call on user space.),
+the signal handler should set the system call return value
+to a sane value,
+by modifying the register context stored in the
+.I ucontext
+argument of the signal handler.
+See
+.BR sigaction (2),
+.BR sigreturn (2),
+and
+.BR getcontext (3)
+for more information.
+.IP
+If
+.I arg2
+is set to
+.BR PR_SYS_DISPATCH_OFF ,
+Syscall User Dispatch is disabled for that thread.
+the remaining arguments must be set to 0.
+.IP
+The setting is not preserved across
+.BR fork (2),
+.BR clone (2),
+or
+.BR execve (2).
+.IP
+For more information,
+see the kernel source file
+.I Documentation/admin\-guide/syscall\-user\-dispatch.rst
+.\" prctl PR_SET_TAGGED_ADDR_CTRL
+.\" commit 63f0c60379650d82250f22e4cf4137ef3dc4f43d
+.TP
+.BR PR_SET_TAGGED_ADDR_CTRL " (since Linux 5.4, only on arm64)"
+Controls support for passing tagged user-space addresses to the kernel
+(i.e., addresses where bits 56\[em]63 are not all zero).
+.IP
+The level of support is selected by
+.IR "arg2" ,
+which can be one of the following:
+.RS
+.TP
+.B 0
+Addresses that are passed
+for the purpose of being dereferenced by the kernel
+must be untagged.
+.TP
+.B PR_TAGGED_ADDR_ENABLE
+Addresses that are passed
+for the purpose of being dereferenced by the kernel
+may be tagged, with the exceptions summarized below.
+.RE
+.IP
+The remaining arguments
+.IR arg3 ", " arg4 ", and " arg5
+must all be zero.
+.\" Enforcement added in
+.\" commit 3e91ec89f527b9870fe42dcbdb74fd389d123a95
+.IP
+On success, the mode specified in
+.I arg2
+is set for the calling thread and the return value is 0.
+If the arguments are invalid,
+the mode specified in
+.I arg2
+is unrecognized,
+or if this feature is unsupported by the kernel
+or disabled via
+.IR /proc/sys/abi/tagged_addr_disabled ,
+the call fails with the error
+.BR EINVAL .
+.IP
+In particular, if
+.BR prctl ( PR_SET_TAGGED_ADDR_CTRL ,
+0, 0, 0, 0)
+fails with
+.BR EINVAL ,
+then all addresses passed to the kernel must be untagged.
+.IP
+Irrespective of which mode is set,
+addresses passed to certain interfaces
+must always be untagged:
+.RS
+.IP \[bu] 3
+.BR brk (2),
+.BR mmap (2),
+.BR shmat (2),
+.BR shmdt (2),
+and the
+.I new_address
+argument of
+.BR mremap (2).
+.IP
+(Prior to Linux 5.6 these accepted tagged addresses,
+but the behaviour may not be what you expect.
+Don't rely on it.)
+.IP \[bu]
+\[oq]polymorphic\[cq] interfaces
+that accept pointers to arbitrary types cast to a
+.I void *
+or other generic type, specifically
+.BR prctl (),
+.BR ioctl (2),
+and in general
+.BR setsockopt (2)
+(only certain specific
+.BR setsockopt (2)
+options allow tagged addresses).
+.RE
+.IP
+This list of exclusions may shrink
+when moving from one kernel version to a later kernel version.
+While the kernel may make some guarantees
+for backwards compatibility reasons,
+for the purposes of new software
+the effect of passing tagged addresses to these interfaces
+is unspecified.
+.IP
+The mode set by this call is inherited across
+.BR fork (2)
+and
+.BR clone (2).
+The mode is reset by
+.BR execve (2)
+to 0
+(i.e., tagged addresses not permitted in the user/kernel ABI).
+.IP
+For more information, see the kernel source file
+.IR Documentation/arm64/tagged\-address\-abi.rst .
+.IP
+.B Warning:
+This call is primarily intended for use by the run-time environment.
+A successful
+.B PR_SET_TAGGED_ADDR_CTRL
+call elsewhere may crash the calling process.
+The conditions for using it safely are complex and system-dependent.
+Don't use it unless you know what you are doing.
+.\" prctl PR_GET_TAGGED_ADDR_CTRL
+.\" commit 63f0c60379650d82250f22e4cf4137ef3dc4f43d
+.TP
+.BR PR_GET_TAGGED_ADDR_CTRL " (since Linux 5.4, only on arm64)"
+Returns the current tagged address mode
+for the calling thread.
+.IP
+Arguments
+.IR arg2 ", " arg3 ", " arg4 ", and " arg5
+must all be zero.
+.IP
+If the arguments are invalid
+or this feature is disabled or unsupported by the kernel,
+the call fails with
+.BR EINVAL .
+In particular, if
+.BR prctl ( PR_GET_TAGGED_ADDR_CTRL ,
+0, 0, 0, 0)
+fails with
+.BR EINVAL ,
+then this feature is definitely either unsupported,
+or disabled via
+.IR /proc/sys/abi/tagged_addr_disabled .
+In this case,
+all addresses passed to the kernel must be untagged.
+.IP
+Otherwise, the call returns a nonnegative value
+describing the current tagged address mode,
+encoded in the same way as the
+.I arg2
+argument of
+.BR PR_SET_TAGGED_ADDR_CTRL .
+.IP
+For more information, see the kernel source file
+.IR Documentation/arm64/tagged\-address\-abi.rst .
+.\"
+.\" prctl PR_TASK_PERF_EVENTS_DISABLE
+.TP
+.BR PR_TASK_PERF_EVENTS_DISABLE " (since Linux 2.6.31)"
+Disable all performance counters attached to the calling process,
+regardless of whether the counters were created by
+this process or another process.
+Performance counters created by the calling process for other
+processes are unaffected.
+For more information on performance counters, see the Linux kernel source file
+.IR tools/perf/design.txt .
+.IP
+Originally called
+.BR PR_TASK_PERF_COUNTERS_DISABLE ;
+.\" commit 1d1c7ddbfab358445a542715551301b7fc363e28
+renamed (retaining the same numerical value)
+in Linux 2.6.32.
+.\"
+.\" prctl PR_TASK_PERF_EVENTS_ENABLE
+.TP
+.BR PR_TASK_PERF_EVENTS_ENABLE " (since Linux 2.6.31)"
+The converse of
+.BR PR_TASK_PERF_EVENTS_DISABLE ;
+enable performance counters attached to the calling process.
+.IP
+Originally called
+.BR PR_TASK_PERF_COUNTERS_ENABLE ;
+.\" commit 1d1c7ddbfab358445a542715551301b7fc363e28
+renamed
+.\" commit cdd6c482c9ff9c55475ee7392ec8f672eddb7be6
+in Linux 2.6.32.
+.\"
+.\" prctl PR_SET_THP_DISABLE
+.TP
+.BR PR_SET_THP_DISABLE " (since Linux 3.15)"
+.\" commit a0715cc22601e8830ace98366c0c2bd8da52af52
+Set the state of the "THP disable" flag for the calling thread.
+If
+.I arg2
+has a nonzero value, the flag is set, otherwise it is cleared.
+Setting this flag provides a method
+for disabling transparent huge pages
+for jobs where the code cannot be modified, and using a malloc hook with
+.BR madvise (2)
+is not an option (i.e., statically allocated data).
+The setting of the "THP disable" flag is inherited by a child created via
+.BR fork (2)
+and is preserved across
+.BR execve (2).
+.\" prctl PR_GET_THP_DISABLE
+.TP
+.BR PR_GET_THP_DISABLE " (since Linux 3.15)"
+Return (as the function result) the current setting of the "THP disable"
+flag for the calling thread:
+either 1, if the flag is set, or 0, if it is not.
+.\" prctl PR_GET_TID_ADDRESS
+.TP
+.BR PR_GET_TID_ADDRESS " (since Linux 3.5)"
+.\" commit 300f786b2683f8bb1ec0afb6e1851183a479c86d
+Return the
+.I clear_child_tid
+address set by
+.BR set_tid_address (2)
+and the
+.BR clone (2)
+.B CLONE_CHILD_CLEARTID
+flag, in the location pointed to by
+.IR "(int\~**)\~arg2" .
+This feature is available only if the kernel is built with the
+.B CONFIG_CHECKPOINT_RESTORE
+option enabled.
+Note that since the
+.BR prctl ()
+system call does not have a compat implementation for
+the AMD64 x32 and MIPS n32 ABIs,
+and the kernel writes out a pointer using the kernel's pointer size,
+this operation expects a user-space buffer of 8 (not 4) bytes on these ABIs.
+.\" prctl PR_SET_TIMERSLACK
+.TP
+.BR PR_SET_TIMERSLACK " (since Linux 2.6.28)"
+.\" See https://lwn.net/Articles/369549/
+.\" commit 6976675d94042fbd446231d1bd8b7de71a980ada
+Each thread has two associated timer slack values:
+a "default" value, and a "current" value.
+This operation sets the "current" timer slack value for the calling thread.
+.I arg2
+is an unsigned long value, then maximum "current" value is ULONG_MAX and
+the minimum "current" value is 1.
+If the nanosecond value supplied in
+.I arg2
+is greater than zero, then the "current" value is set to this value.
+If
+.I arg2
+is equal to zero,
+the "current" timer slack is reset to the
+thread's "default" timer slack value.
+.IP
+The "current" timer slack is used by the kernel to group timer expirations
+for the calling thread that are close to one another;
+as a consequence, timer expirations for the thread may be
+up to the specified number of nanoseconds late (but will never expire early).
+Grouping timer expirations can help reduce system power consumption
+by minimizing CPU wake-ups.
+.IP
+The timer expirations affected by timer slack are those set by
+.BR select (2),
+.BR pselect (2),
+.BR poll (2),
+.BR ppoll (2),
+.BR epoll_wait (2),
+.BR epoll_pwait (2),
+.BR clock_nanosleep (2),
+.BR nanosleep (2),
+and
+.BR futex (2)
+(and thus the library functions implemented via futexes, including
+.\" List obtained by grepping for futex usage in glibc source
+.BR pthread_cond_timedwait (3),
+.BR pthread_mutex_timedlock (3),
+.BR pthread_rwlock_timedrdlock (3),
+.BR pthread_rwlock_timedwrlock (3),
+and
+.BR sem_timedwait (3)).
+.IP
+Timer slack is not applied to threads that are scheduled under
+a real-time scheduling policy (see
+.BR sched_setscheduler (2)).
+.IP
+When a new thread is created,
+the two timer slack values are made the same as the "current" value
+of the creating thread.
+Thereafter, a thread can adjust its "current" timer slack value via
+.BR PR_SET_TIMERSLACK .
+The "default" value can't be changed.
+The timer slack values of
+.I init
+(PID 1), the ancestor of all processes,
+are 50,000 nanoseconds (50 microseconds).
+The timer slack value is inherited by a child created via
+.BR fork (2),
+and is preserved across
+.BR execve (2).
+.IP
+Since Linux 4.6, the "current" timer slack value of any process
+can be examined and changed via the file
+.IR /proc/ pid /timerslack_ns .
+See
+.BR proc (5).
+.\" prctl PR_GET_TIMERSLACK
+.TP
+.BR PR_GET_TIMERSLACK " (since Linux 2.6.28)"
+Return (as the function result)
+the "current" timer slack value of the calling thread.
+.\" prctl PR_SET_TIMING
+.TP
+.BR PR_SET_TIMING " (since Linux 2.6.0)"
+.\" Precisely: Linux 2.6.0-test4
+Set whether to use (normal, traditional) statistical process timing or
+accurate timestamp-based process timing, by passing
+.B PR_TIMING_STATISTICAL
+.\" 0
+or
+.B PR_TIMING_TIMESTAMP
+.\" 1
+to \fIarg2\fP.
+.B PR_TIMING_TIMESTAMP
+is not currently implemented
+(attempting to set this mode will yield the error
+.BR EINVAL ).
+.\" PR_TIMING_TIMESTAMP doesn't do anything in Linux 2.6.26-rc8,
+.\" and looking at the patch history, it appears
+.\" that it never did anything.
+.\" prctl PR_GET_TIMING
+.TP
+.BR PR_GET_TIMING " (since Linux 2.6.0)"
+.\" Precisely: Linux 2.6.0-test4
+Return (as the function result) which process timing method is currently
+in use.
+.\" prctl PR_SET_TSC
+.TP
+.BR PR_SET_TSC " (since Linux 2.6.26, x86 only)"
+Set the state of the flag determining whether the timestamp counter
+can be read by the process.
+Pass
+.B PR_TSC_ENABLE
+to
+.I arg2
+to allow it to be read, or
+.B PR_TSC_SIGSEGV
+to generate a
+.B SIGSEGV
+when the process tries to read the timestamp counter.
+.\" prctl PR_GET_TSC
+.TP
+.BR PR_GET_TSC " (since Linux 2.6.26, x86 only)"
+Return the state of the flag determining whether the timestamp counter
+can be read,
+in the location pointed to by
+.IR "(int\~*) arg2" .
+.\" prctl PR_SET_UNALIGN
+.TP
+.B PR_SET_UNALIGN
+(Only on: ia64, since Linux 2.3.48; parisc, since Linux 2.6.15;
+PowerPC, since Linux 2.6.18; Alpha, since Linux 2.6.22;
+.\" sh: 94ea5e449ae834af058ef005d16a8ad44fcf13d6
+.\" tile: 2f9ac29eec71a696cb0dcc5fb82c0f8d4dac28c9
+sh, since Linux 2.6.34; tile, since Linux 3.12)
+Set unaligned access control bits to \fIarg2\fP.
+Pass
+\fBPR_UNALIGN_NOPRINT\fP to silently fix up unaligned user accesses,
+or \fBPR_UNALIGN_SIGBUS\fP to generate
+.B SIGBUS
+on unaligned user access.
+Alpha also supports an additional flag with the value
+of 4 and no corresponding named constant,
+which instructs kernel to not fix up
+unaligned accesses (it is analogous to providing the
+.B UAC_NOFIX
+flag in
+.B SSI_NVPAIRS
+operation of the
+.BR setsysinfo ()
+system call on Tru64).
+.\" prctl PR_GET_UNALIGN
+.TP
+.B PR_GET_UNALIGN
+(See
+.B PR_SET_UNALIGN
+for information on versions and architectures.)
+Return unaligned access control bits, in the location pointed to by
+.IR "(unsigned int\~*) arg2" .
+.\" prctl PR_GET_AUXV
+.TP
+.BR PR_GET_AUXV " (since Linux 6.4)"
+Get the auxiliary vector (auxv) into the buffer pointed to by
+.IR "(void\~*) arg2" ,
+whose length is given by \fIarg3\fP.
+If the buffer is not long enough for the full auxiliary vector,
+the copy will be truncated.
+Return (as the function result)
+the full length of the auxiliary vector.
+\fIarg4\fP and \fIarg5\fP must be 0.
+.TP
+.BR PR_SET_MDWE " (since Linux 6.3)"
+.\" commit b507808ebce23561d4ff8c2aa1fb949fe402bc61
+Set the calling process' Memory-Deny-Write-Execute protection mask.
+Once protection bits are set,
+they can not be changed.
+.I arg2
+must be a bit mask of:
+.RS
+.TP
+.B PR_MDWE_REFUSE_EXEC_GAIN
+New memory mapping protections can't be writable and executable.
+Non-executable mappings can't become executable.
+.TP
+.B PR_MDWE_NO_INHERIT " (since Linux 6.6)"
+.\" commit 2a87e5520554034e8c423479740f95bea4a086a0
+Do not propagate MDWE protection to child processes on
+.BR fork (2).
+Setting this bit requires setting
+.B PR_MDWE_REFUSE_EXEC_GAIN
+too.
+.RE
+.TP
+.BR PR_GET_MDWE " (since Linux 6.3)"
+.\" commit b507808ebce23561d4ff8c2aa1fb949fe402bc61
+Return (as the function result) the Memory-Deny-Write-Execute protection mask
+of the calling process.
+(See
+.B PR_SET_MDWE
+for information on the protection mask bits.)
+.SH RETURN VALUE
+On success,
+.BR PR_CAP_AMBIENT + PR_CAP_AMBIENT_IS_SET ,
+.BR PR_CAPBSET_READ ,
+.BR PR_GET_DUMPABLE ,
+.BR PR_GET_FP_MODE ,
+.BR PR_GET_IO_FLUSHER ,
+.BR PR_GET_KEEPCAPS ,
+.BR PR_MCE_KILL_GET ,
+.BR PR_GET_NO_NEW_PRIVS ,
+.BR PR_GET_SECUREBITS ,
+.BR PR_GET_SPECULATION_CTRL ,
+.BR PR_SVE_GET_VL ,
+.BR PR_SVE_SET_VL ,
+.BR PR_GET_TAGGED_ADDR_CTRL ,
+.BR PR_GET_THP_DISABLE ,
+.BR PR_GET_TIMING ,
+.BR PR_GET_TIMERSLACK ,
+.BR PR_GET_AUXV ,
+and (if it returns)
+.B PR_GET_SECCOMP
+return the nonnegative values described above.
+All other
+.I op
+values return 0 on success.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.I op
+is
+.B PR_SET_SECCOMP
+and
+.I arg2
+is
+.BR SECCOMP_MODE_FILTER ,
+but the process does not have the
+.B CAP_SYS_ADMIN
+capability or has not set the
+.I no_new_privs
+attribute (see the discussion of
+.B PR_SET_NO_NEW_PRIVS
+above).
+.TP
+.B EACCES
+.I op
+is
+.BR PR_SET_MM ,
+and
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+the file is not executable.
+.TP
+.B EBADF
+.I op
+is
+.BR PR_SET_MM ,
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+and the file descriptor passed in
+.I arg4
+is not valid.
+.TP
+.B EBUSY
+.I op
+is
+.BR PR_SET_MM ,
+.I arg3
+is
+.BR PR_SET_MM_EXE_FILE ,
+and this the second attempt to change the
+.IR /proc/ pid /exe
+symbolic link, which is prohibited.
+.TP
+.B EFAULT
+.I arg2
+is an invalid address.
+.TP
+.B EFAULT
+.I op
+is
+.BR PR_SET_SECCOMP ,
+.I arg2
+is
+.BR SECCOMP_MODE_FILTER ,
+the system was built with
+.BR CONFIG_SECCOMP_FILTER ,
+and
+.I arg3
+is an invalid address.
+.TP
+.B EFAULT
+.I op
+is
+.B PR_SET_SYSCALL_USER_DISPATCH
+and
+.I arg5
+has an invalid address.
+.TP
+.B EINVAL
+The value of
+.I op
+is not recognized,
+or not supported on this system.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_MCE_KILL
+or
+.B PR_MCE_KILL_GET
+or
+.BR PR_SET_MM ,
+and unused
+.BR prctl ()
+arguments were not specified as zero.
+.TP
+.B EINVAL
+.I arg2
+is not valid value for this
+.IR op .
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_SECCOMP
+or
+.BR PR_GET_SECCOMP ,
+and the kernel was not configured with
+.BR CONFIG_SECCOMP .
+.TP
+.B EINVAL
+.I op
+is
+.BR PR_SET_SECCOMP ,
+.I arg2
+is
+.BR SECCOMP_MODE_FILTER ,
+and the kernel was not configured with
+.BR CONFIG_SECCOMP_FILTER .
+.TP
+.B EINVAL
+.I op
+is
+.BR PR_SET_MM ,
+and one of the following is true
+.RS
+.IP \[bu] 3
+.I arg4
+or
+.I arg5
+is nonzero;
+.IP \[bu]
+.I arg3
+is greater than
+.B TASK_SIZE
+(the limit on the size of the user address space for this architecture);
+.IP \[bu]
+.I arg2
+is
+.BR PR_SET_MM_START_CODE ,
+.BR PR_SET_MM_END_CODE ,
+.BR PR_SET_MM_START_DATA ,
+.BR PR_SET_MM_END_DATA ,
+or
+.BR PR_SET_MM_START_STACK ,
+and the permissions of the corresponding memory area are not as required;
+.IP \[bu]
+.I arg2
+is
+.B PR_SET_MM_START_BRK
+or
+.BR PR_SET_MM_BRK ,
+and
+.I arg3
+is less than or equal to the end of the data segment
+or specifies a value that would cause the
+.B RLIMIT_DATA
+resource limit to be exceeded.
+.RE
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_PTRACER
+and
+.I arg2
+is not 0,
+.BR PR_SET_PTRACER_ANY ,
+or the PID of an existing process.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_PDEATHSIG
+and
+.I arg2
+is not a valid signal number.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_DUMPABLE
+and
+.I arg2
+is neither
+.B SUID_DUMP_DISABLE
+nor
+.BR SUID_DUMP_USER .
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_TIMING
+and
+.I arg2
+is not
+.BR PR_TIMING_STATISTICAL .
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_NO_NEW_PRIVS
+and
+.I arg2
+is not equal to 1
+or
+.IR arg3 ,
+.IR arg4 ,
+or
+.I arg5
+is nonzero.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_GET_NO_NEW_PRIVS
+and
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+or
+.I arg5
+is nonzero.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_THP_DISABLE
+and
+.IR arg3 ,
+.IR arg4 ,
+or
+.I arg5
+is nonzero.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_GET_THP_DISABLE
+and
+.IR arg2 ,
+.IR arg3 ,
+.IR arg4 ,
+or
+.I arg5
+is nonzero.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_CAP_AMBIENT
+and an unused argument
+.RI ( arg4 ,
+.IR arg5 ,
+or,
+in the case of
+.BR PR_CAP_AMBIENT_CLEAR_ALL ,
+.IR arg3 )
+is nonzero; or
+.I arg2
+has an invalid value;
+or
+.I arg2
+is
+.BR PR_CAP_AMBIENT_LOWER ,
+.BR PR_CAP_AMBIENT_RAISE ,
+or
+.B PR_CAP_AMBIENT_IS_SET
+and
+.I arg3
+does not specify a valid capability.
+.TP
+.B EINVAL
+.I op
+was
+.B PR_GET_SPECULATION_CTRL
+or
+.B PR_SET_SPECULATION_CTRL
+and unused arguments to
+.BR prctl ()
+are not 0.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_PAC_RESET_KEYS
+and the arguments are invalid or unsupported.
+See the description of
+.B PR_PAC_RESET_KEYS
+above for details.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SVE_SET_VL
+and the arguments are invalid or unsupported,
+or SVE is not available on this platform.
+See the description of
+.B PR_SVE_SET_VL
+above for details.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SVE_GET_VL
+and SVE is not available on this platform.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_SYSCALL_USER_DISPATCH
+and one of the following is true:
+.RS
+.IP \[bu] 3
+.I arg2
+is
+.B PR_SYS_DISPATCH_OFF
+and the remaining arguments are not 0;
+.IP \[bu]
+.I arg2
+is
+.B PR_SYS_DISPATCH_ON
+and the memory range specified is outside the
+address space of the process.
+.IP \[bu]
+.I arg2
+is invalid.
+.RE
+.TP
+.B EINVAL
+.I op
+is
+.B PR_SET_TAGGED_ADDR_CTRL
+and the arguments are invalid or unsupported.
+See the description of
+.B PR_SET_TAGGED_ADDR_CTRL
+above for details.
+.TP
+.B EINVAL
+.I op
+is
+.B PR_GET_TAGGED_ADDR_CTRL
+and the arguments are invalid or unsupported.
+See the description of
+.B PR_GET_TAGGED_ADDR_CTRL
+above for details.
+.TP
+.B ENODEV
+.I op
+was
+.B PR_SET_SPECULATION_CTRL
+the kernel or CPU does not support the requested speculation misfeature.
+.TP
+.B ENXIO
+.I op
+was
+.B PR_MPX_ENABLE_MANAGEMENT
+or
+.B PR_MPX_DISABLE_MANAGEMENT
+and the kernel or the CPU does not support MPX management.
+Check that the kernel and processor have MPX support.
+.TP
+.B ENXIO
+.I op
+was
+.B PR_SET_SPECULATION_CTRL
+implies that the control of the selected speculation misfeature is not possible.
+See
+.B PR_GET_SPECULATION_CTRL
+for the bit fields to determine which option is available.
+.TP
+.B EOPNOTSUPP
+.I op
+is
+.B PR_SET_FP_MODE
+and
+.I arg2
+has an invalid or unsupported value.
+.TP
+.B EPERM
+.I op
+is
+.BR PR_SET_SECUREBITS ,
+and the caller does not have the
+.B CAP_SETPCAP
+capability,
+or tried to unset a "locked" flag,
+or tried to set a flag whose corresponding locked flag was set
+(see
+.BR capabilities (7)).
+.TP
+.B EPERM
+.I op
+is
+.B PR_SET_SPECULATION_CTRL
+wherein the speculation was disabled with
+.B PR_SPEC_FORCE_DISABLE
+and caller tried to enable it again.
+.TP
+.B EPERM
+.I op
+is
+.BR PR_SET_KEEPCAPS ,
+and the caller's
+.B SECBIT_KEEP_CAPS_LOCKED
+flag is set
+(see
+.BR capabilities (7)).
+.TP
+.B EPERM
+.I op
+is
+.BR PR_CAPBSET_DROP ,
+and the caller does not have the
+.B CAP_SETPCAP
+capability.
+.TP
+.B EPERM
+.I op
+is
+.BR PR_SET_MM ,
+and the caller does not have the
+.B CAP_SYS_RESOURCE
+capability.
+.TP
+.B EPERM
+.I op
+is
+.B PR_CAP_AMBIENT
+and
+.I arg2
+is
+.BR PR_CAP_AMBIENT_RAISE ,
+but either the capability specified in
+.I arg3
+is not present in the process's permitted and inheritable capability sets,
+or the
+.B PR_CAP_AMBIENT_LOWER
+securebit has been set.
+.TP
+.B ERANGE
+.I op
+was
+.B PR_SET_SPECULATION_CTRL
+and
+.I arg3
+is not
+.BR PR_SPEC_ENABLE ,
+.BR PR_SPEC_DISABLE ,
+.BR PR_SPEC_FORCE_DISABLE ,
+nor
+.BR PR_SPEC_DISABLE_NOEXEC .
+.SH VERSIONS
+IRIX has a
+.BR prctl ()
+system call (also introduced in Linux 2.1.44
+as irix_prctl on the MIPS architecture),
+with prototype
+.P
+.in +4n
+.EX
+.BI "ptrdiff_t prctl(int " op ", int " arg2 ", int " arg3 );
+.EE
+.in
+.P
+and operations to get the maximum number of processes per user,
+get the maximum number of processors the calling process can use,
+find out whether a specified process is currently blocked,
+get or set the maximum stack size, and so on.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.1.57,
+glibc 2.0.6
+.SH SEE ALSO
+.BR signal (2),
+.BR core (5)
diff --git a/man/man2/pread.2 b/man/man2/pread.2
new file mode 100644
index 000000000..e80680b48
--- /dev/null
+++ b/man/man2/pread.2
@@ -0,0 +1,146 @@
+.\" Copyright (C) 1999 Joseph Samuel Myers.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pread 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pread, pwrite \- read from or write to a file descriptor at a given offset
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "ssize_t pread(int " fd ", void " buf [. count "], size_t " count ,
+.BI "              off_t " offset );
+.BI "ssize_t pwrite(int " fd ", const void " buf [. count "], size_t " count ,
+.BI "              off_t " offset );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pread (),
+.BR pwrite ():
+.nf
+    _XOPEN_SOURCE >= 500
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+.fi
+.SH DESCRIPTION
+.BR pread ()
+reads up to
+.I count
+bytes from file descriptor
+.I fd
+at offset
+.I offset
+(from the start of the file) into the buffer starting at
+.IR buf .
+The file offset is not changed.
+.P
+.BR pwrite ()
+writes up to
+.I count
+bytes from the buffer starting at
+.I buf
+to the file descriptor
+.I fd
+at offset
+.IR offset .
+The file offset is not changed.
+.P
+The file referenced by
+.I fd
+must be capable of seeking.
+.SH RETURN VALUE
+On success,
+.BR pread ()
+returns the number of bytes read
+(a return of zero indicates end of file)
+and
+.BR pwrite ()
+returns the number of bytes written.
+.P
+Note that it is not an error for a successful call to transfer fewer bytes
+than requested (see
+.BR read (2)
+and
+.BR write (2)).
+.P
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR pread ()
+can fail and set
+.I errno
+to any error specified for
+.BR read (2)
+or
+.BR lseek (2).
+.BR pwrite ()
+can fail and set
+.I errno
+to any error specified for
+.BR write (2)
+or
+.BR lseek (2).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Added in Linux 2.1.60;
+the entries in the i386 system call table were added in Linux 2.1.69.
+C library support (including emulation using
+.BR lseek (2)
+on older kernels without the system calls) was added in glibc 2.1.
+.SS C library/kernel differences
+On Linux, the underlying system calls were renamed
+in Linux 2.6:
+.BR pread ()
+became
+.BR pread64 (),
+and
+.BR pwrite ()
+became
+.BR pwrite64 ().
+The system call numbers remained the same.
+The glibc
+.BR pread ()
+and
+.BR pwrite ()
+wrapper functions transparently deal with the change.
+.P
+On some 32-bit architectures,
+the calling signature for these system calls differ,
+for the reasons described in
+.BR syscall (2).
+.SH NOTES
+The
+.BR pread ()
+and
+.BR pwrite ()
+system calls are especially useful in multithreaded applications.
+They allow multiple threads to perform I/O on the same file descriptor
+without being affected by changes to the file offset by other threads.
+.SH BUGS
+POSIX requires that opening a file with the
+.B O_APPEND
+flag should have no effect on the location at which
+.BR pwrite ()
+writes data.
+However, on Linux, if a file is opened with
+.\" FIXME . https://bugzilla.kernel.org/show_bug.cgi?id=43178
+.BR O_APPEND ,
+.BR pwrite ()
+appends data to the end of the file, regardless of the value of
+.IR offset .
+.SH SEE ALSO
+.BR lseek (2),
+.BR read (2),
+.BR readv (2),
+.BR write (2)
diff --git a/man/man2/pread64.2 b/man/man2/pread64.2
new file mode 100644
index 000000000..87eacb238
--- /dev/null
+++ b/man/man2/pread64.2
@@ -0,0 +1 @@
+.so man2/pread.2
diff --git a/man/man2/preadv.2 b/man/man2/preadv.2
new file mode 100644
index 000000000..54e3384ef
--- /dev/null
+++ b/man/man2/preadv.2
@@ -0,0 +1 @@
+.so man2/readv.2
diff --git a/man/man2/preadv2.2 b/man/man2/preadv2.2
new file mode 100644
index 000000000..54e3384ef
--- /dev/null
+++ b/man/man2/preadv2.2
@@ -0,0 +1 @@
+.so man2/readv.2
diff --git a/man/man2/prlimit.2 b/man/man2/prlimit.2
new file mode 100644
index 000000000..df6d7362a
--- /dev/null
+++ b/man/man2/prlimit.2
@@ -0,0 +1 @@
+.so man2/getrlimit.2
diff --git a/man/man2/prlimit64.2 b/man/man2/prlimit64.2
new file mode 100644
index 000000000..df6d7362a
--- /dev/null
+++ b/man/man2/prlimit64.2
@@ -0,0 +1 @@
+.so man2/getrlimit.2
diff --git a/man/man2/process_madvise.2 b/man/man2/process_madvise.2
new file mode 100644
index 000000000..2c9f0b3f9
--- /dev/null
+++ b/man/man2/process_madvise.2
@@ -0,0 +1,200 @@
+.\" Copyright (C) 2021 Suren Baghdasaryan <surenb@google.com>
+.\" and Copyright (C) 2021 Minchan Kim <minchan@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Commit ecb8ac8b1f146915aa6b96449b66dd48984caacc
+.\"
+.TH process_madvise 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+process_madvise \- give advice about use of memory to a process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "ssize_t process_madvise(int " pidfd ", const struct iovec " iovec [. n ],
+.BI "                        size_t " n ", int " advice \
+", unsigned int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR process_madvise ()
+system call is used to give advice or directions to the kernel about the
+address ranges of another process or of the calling process.
+It provides the advice for the address ranges described by
+.I iovec
+and
+.IR n .
+The goal of such advice is to improve system or application performance.
+.P
+The
+.I pidfd
+argument is a PID file descriptor (see
+.BR pidfd_open (2))
+that specifies the process to which the advice is to be applied.
+.P
+The pointer
+.I iovec
+points to an array of
+.I iovec
+structures, described in
+.BR iovec (3type).
+.P
+.I n
+specifies the number of elements in the array of
+.I iovec
+structures.
+This value must be less than or equal to
+.B IOV_MAX
+(defined in
+.I <limits.h>
+or accessible via the call
+.IR sysconf(_SC_IOV_MAX) ).
+.P
+The
+.I advice
+argument is one of the following values:
+.TP
+.B MADV_COLD
+See
+.BR madvise (2).
+.TP
+.B MADV_COLLAPSE
+See
+.BR madvise (2).
+.TP
+.B MADV_PAGEOUT
+See
+.BR madvise (2).
+.TP
+.B MADV_WILLNEED
+See
+.BR madvise (2).
+.P
+The
+.I flags
+argument is reserved for future use; currently, this argument must be
+specified as 0.
+.P
+The
+.I n
+and
+.I iovec
+arguments are checked before applying any advice.
+If
+.I n
+is too big, or
+.I iovec
+is invalid,
+then an error will be returned immediately and no advice will be applied.
+.P
+The advice might be applied to only a part of
+.I iovec
+if one of its elements points to an invalid memory region in the
+remote process.
+No further elements will be processed beyond that point.
+(See the discussion regarding partial advice in RETURN VALUE.)
+.P
+.\" commit 96cfe2c0fd23ea7c2368d14f769d287e7ae1082e
+Starting in Linux 5.12,
+permission to apply advice to another process is governed by
+ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check (see
+.BR ptrace (2));
+in addition,
+because of the performance implications of applying the advice,
+the caller must have the
+.B CAP_SYS_NICE
+capability
+(see
+.BR capabilities (7)).
+.SH RETURN VALUE
+On success,
+.BR process_madvise ()
+returns the number of bytes advised.
+This return value may be less than the total number of requested bytes,
+if an error occurred after some
+.I iovec
+elements were already processed.
+The caller should check the return value to determine whether a partial
+advice occurred.
+.P
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I pidfd
+is not a valid PID file descriptor.
+.TP
+.B EFAULT
+The memory described by
+.I iovec
+is outside the accessible address space of the process referred to by
+.IR pidfd .
+.TP
+.B EINVAL
+.I flags
+is not 0.
+.TP
+.B EINVAL
+The sum of the
+.I iov_len
+values of
+.I iovec
+overflows a
+.I ssize_t
+value.
+.TP
+.B EINVAL
+.I n
+is too large.
+.TP
+.B ENOMEM
+Could not allocate memory for internal copies of the
+.I iovec
+structures.
+.TP
+.B EPERM
+The caller does not have permission to access the address space of the process
+.IR pidfd .
+.TP
+.B ESRCH
+The target process does not exist (i.e., it has terminated and been waited on).
+.P
+See
+.BR madvise (2)
+for
+.IR advice -specific
+errors.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 5.10.
+.\" Linux commit ecb8ac8b1f146915aa6b96449b66dd48984caacc
+glibc 2.36.
+.\" glibc commit d19ee3473d68ca0e794f3a8b7677a0983ae1342e
+.P
+Support for this system call is optional,
+depending on the setting of the
+.B CONFIG_ADVISE_SYSCALLS
+configuration option.
+.P
+When this system call first appeared in Linux 5.10,
+permission to apply advice to another process was entirely governed by
+ptrace access mode
+.B PTRACE_MODE_ATTACH_FSCREDS
+check (see
+.BR ptrace (2)).
+This requirement was relaxed in Linux 5.12 so that the caller didn't require
+full control over the target process.
+.SH SEE ALSO
+.BR madvise (2),
+.BR pidfd_open (2),
+.BR process_vm_readv (2),
+.BR process_vm_write (2)
diff --git a/man/man2/process_vm_readv.2 b/man/man2/process_vm_readv.2
new file mode 100644
index 000000000..3a25cd8f5
--- /dev/null
+++ b/man/man2/process_vm_readv.2
@@ -0,0 +1,314 @@
+.\" Copyright (C) 2011 Christopher Yeoh <cyeoh@au1.ibm.com>
+.\" and Copyright (C) 2012 Mike Frysinger <vapier@gentoo.org>
+.\" and Copyright (C) 2012 Michael Kerrisk <mtk.man-pages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Commit fcf634098c00dd9cd247447368495f0b79be12d1
+.\"
+.TH process_vm_readv 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+process_vm_readv, process_vm_writev \-
+transfer data between process address spaces
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/uio.h>
+.P
+.BI "ssize_t process_vm_readv(pid_t " pid ,
+.BI "                       const struct iovec *" local_iov ,
+.BI "                       unsigned long " liovcnt ,
+.BI "                       const struct iovec *" remote_iov ,
+.BI "                       unsigned long " riovcnt ,
+.BI "                       unsigned long " flags ");"
+.BI "ssize_t process_vm_writev(pid_t " pid ,
+.BI "                       const struct iovec *" local_iov ,
+.BI "                       unsigned long " liovcnt ,
+.BI "                       const struct iovec *" remote_iov ,
+.BI "                       unsigned long " riovcnt ,
+.BI "                       unsigned long " flags ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR process_vm_readv (),
+.BR process_vm_writev ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+These system calls transfer data between the address space
+of the calling process ("the local process") and the process identified by
+.I pid
+("the remote process").
+The data moves directly between the address spaces of the two processes,
+without passing through kernel space.
+.P
+The
+.BR process_vm_readv ()
+system call transfers data from the remote process to the local process.
+The data to be transferred is identified by
+.I remote_iov
+and
+.IR riovcnt :
+.I remote_iov
+is a pointer to an array describing address ranges in the process
+.IR pid ,
+and
+.I riovcnt
+specifies the number of elements in
+.IR remote_iov .
+The data is transferred to the locations specified by
+.I local_iov
+and
+.IR liovcnt :
+.I local_iov
+is a pointer to an array describing address ranges in the calling process,
+and
+.I liovcnt
+specifies the number of elements in
+.IR local_iov .
+.P
+The
+.BR process_vm_writev ()
+system call is the converse of
+.BR process_vm_readv ()\[em]it
+transfers data from the local process to the remote process.
+Other than the direction of the transfer, the arguments
+.IR liovcnt ,
+.IR local_iov ,
+.IR riovcnt ,
+and
+.I remote_iov
+have the same meaning as for
+.BR process_vm_readv ().
+.P
+The
+.I local_iov
+and
+.I remote_iov
+arguments point to an array of
+.I iovec
+structures, described in
+.BR iovec (3type).
+.P
+Buffers are processed in array order.
+This means that
+.BR process_vm_readv ()
+completely fills
+.I local_iov[0]
+before proceeding to
+.IR local_iov[1] ,
+and so on.
+Likewise,
+.I remote_iov[0]
+is completely read before proceeding to
+.IR remote_iov[1] ,
+and so on.
+.P
+Similarly,
+.BR process_vm_writev ()
+writes out the entire contents of
+.I local_iov[0]
+before proceeding to
+.IR local_iov[1] ,
+and it completely fills
+.I remote_iov[0]
+before proceeding to
+.IR remote_iov[1] .
+.P
+The lengths of
+.I remote_iov[i].iov_len
+and
+.I local_iov[i].iov_len
+do not have to be the same.
+Thus, it is possible to split a single local buffer
+into multiple remote buffers, or vice versa.
+.P
+The
+.I flags
+argument is currently unused and must be set to 0.
+.P
+The values specified in the
+.I liovcnt
+and
+.I riovcnt
+arguments must be less than or equal to
+.B IOV_MAX
+(defined in
+.I <limits.h>
+or accessible via the call
+.IR sysconf(_SC_IOV_MAX) ).
+.\" In time, glibc might provide a wrapper that works around this limit,
+.\" as is done for readv()/writev()
+.P
+The count arguments and
+.I local_iov
+are checked before doing any transfers.
+If the counts are too big, or
+.I local_iov
+is invalid,
+or the addresses refer to regions that are inaccessible to the local process,
+none of the vectors will be processed
+and an error will be returned immediately.
+.P
+Note, however, that these system calls do not check the memory regions
+in the remote process until just before doing the read/write.
+Consequently, a partial read/write (see RETURN VALUE)
+may result if one of the
+.I remote_iov
+elements points to an invalid memory region in the remote process.
+No further reads/writes will be attempted beyond that point.
+Keep this in mind when attempting to read data of unknown length
+(such as C strings that are null-terminated) from a remote process,
+by avoiding spanning memory pages (typically 4\ KiB) in a single remote
+.I iovec
+element.
+(Instead, split the remote read into two
+.I remote_iov
+elements and have them merge back into a single write
+.I local_iov
+entry.
+The first read entry goes up to the page boundary,
+while the second starts on the next page boundary.)
+.P
+Permission to read from or write to another process
+is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_REALCREDS
+check; see
+.BR ptrace (2).
+.SH RETURN VALUE
+On success,
+.BR process_vm_readv ()
+returns the number of bytes read and
+.BR process_vm_writev ()
+returns the number of bytes written.
+This return value may be less than the total number of requested bytes,
+if a partial read/write occurred.
+(Partial transfers apply at the granularity of
+.I iovec
+elements.
+These system calls won't perform a partial transfer that splits a single
+.I iovec
+element.)
+The caller should check the return value to determine whether
+a partial read/write occurred.
+.P
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+The memory described by
+.I local_iov
+is outside the caller's accessible address space.
+.TP
+.B EFAULT
+The memory described by
+.I remote_iov
+is outside the accessible address space of the process
+.IR pid .
+.TP
+.B EINVAL
+The sum of the
+.I iov_len
+values of either
+.I local_iov
+or
+.I remote_iov
+overflows a
+.I ssize_t
+value.
+.TP
+.B EINVAL
+.I flags
+is not 0.
+.TP
+.B EINVAL
+.I liovcnt
+or
+.I riovcnt
+is too large.
+.TP
+.B ENOMEM
+Could not allocate memory for internal copies of the
+.I iovec
+structures.
+.TP
+.B EPERM
+The caller does not have permission to access the address space of the process
+.IR pid .
+.TP
+.B ESRCH
+No process with ID
+.I pid
+exists.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.2,
+glibc 2.15.
+.SH NOTES
+The data transfers performed by
+.BR process_vm_readv ()
+and
+.BR process_vm_writev ()
+are not guaranteed to be atomic in any way.
+.P
+These system calls were designed to permit fast message passing
+by allowing messages to be exchanged with a single copy operation
+(rather than the double copy that would be required
+when using, for example, shared memory or pipes).
+.\" Original user is MPI, http://www.mcs.anl.gov/research/projects/mpi/
+.\" See also some benchmarks at http://lwn.net/Articles/405284/
+.\" and http://marc.info/?l=linux-mm&m=130105930902915&w=2
+.SH EXAMPLES
+The following code sample demonstrates the use of
+.BR process_vm_readv ().
+It reads 20 bytes at the address 0x10000 from the process with PID 10
+and writes the first 10 bytes into
+.I buf1
+and the second 10 bytes into
+.IR buf2 .
+.P
+.\" SRC BEGIN (process_vm_readv.c)
+.EX
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+\&
+int
+main(void)
+{
+    char          buf1[10];
+    char          buf2[10];
+    pid_t         pid = 10;    /* PID of remote process */
+    ssize_t       nread;
+    struct iovec  local[2];
+    struct iovec  remote[1];
+\&
+    local[0].iov_base = buf1;
+    local[0].iov_len = 10;
+    local[1].iov_base = buf2;
+    local[1].iov_len = 10;
+    remote[0].iov_base = (void *) 0x10000;
+    remote[0].iov_len = 20;
+\&
+    nread = process_vm_readv(pid, local, 2, remote, 1, 0);
+    if (nread != 20)
+        exit(EXIT_FAILURE);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR readv (2),
+.BR writev (2)
diff --git a/man/man2/process_vm_writev.2 b/man/man2/process_vm_writev.2
new file mode 100644
index 000000000..7b198a9a4
--- /dev/null
+++ b/man/man2/process_vm_writev.2
@@ -0,0 +1 @@
+.so man2/process_vm_readv.2
diff --git a/man/man2/prof.2 b/man/man2/prof.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/prof.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/pselect.2 b/man/man2/pselect.2
new file mode 100644
index 000000000..e17784318
--- /dev/null
+++ b/man/man2/pselect.2
@@ -0,0 +1 @@
+.so man2/select.2
diff --git a/man/man2/pselect6.2 b/man/man2/pselect6.2
new file mode 100644
index 000000000..e17784318
--- /dev/null
+++ b/man/man2/pselect6.2
@@ -0,0 +1 @@
+.so man2/select.2
diff --git a/man/man2/ptrace.2 b/man/man2/ptrace.2
new file mode 100644
index 000000000..c6487656c
--- /dev/null
+++ b/man/man2/ptrace.2
@@ -0,0 +1,2986 @@
+.\" Copyright (c) 1993 Michael Haardt <michael@moria.de>
+.\" Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" and changes Copyright (C) 1999 Mike Coleman (mkc@acm.org)
+.\" -- major revision to fully document ptrace semantics per recent Linux
+.\"    kernel (2.2.10) and glibc (2.1.2)
+.\" Sun Nov  7 03:18:35 CST 1999
+.\"
+.\" and Copyright (c) 2011, Denys Vlasenko <vda.linux@googlemail.com>
+.\" and Copyright (c) 2015, 2016, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Fri Jul 23 23:47:18 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Fri Jan 31 16:46:30 1997 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Thu Oct  7 17:28:49 1999 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.\" 2006-03-24, Chuck Ebbert <76306.1226@compuserve.com>
+.\"    Added    PTRACE_SETOPTIONS, PTRACE_GETEVENTMSG, PTRACE_GETSIGINFO,
+.\"        PTRACE_SETSIGINFO, PTRACE_SYSEMU, PTRACE_SYSEMU_SINGLESTEP
+.\"    (Thanks to Blaisorblade, Daniel Jacobowitz and others who helped.)
+.\" 2011-09, major update by Denys Vlasenko <vda.linux@googlemail.com>
+.\" 2015-01, Kees Cook <keescook@chromium.org>
+.\"    Added PTRACE_O_TRACESECCOMP, PTRACE_EVENT_SECCOMP
+.\"
+.\" FIXME The following are undocumented:
+.\"
+.\" PTRACE_GETWMMXREGS
+.\" PTRACE_SETWMMXREGS
+.\"	ARM
+.\" 	Linux 2.6.12
+.\"
+.\" PTRACE_SET_SYSCALL
+.\"	ARM and ARM64
+.\"	Linux 2.6.16
+.\"	commit 3f471126ee53feb5e9b210ea2f525ed3bb9b7a7f
+.\"	Author: Nicolas Pitre <nico@cam.org>
+.\"	Date:   Sat Jan 14 19:30:04 2006 +0000
+.\"
+.\" PTRACE_GETCRUNCHREGS
+.\" PTRACE_SETCRUNCHREGS
+.\"	ARM
+.\"	Linux 2.6.18
+.\"	commit 3bec6ded282b331552587267d67a06ed7fd95ddd
+.\"	Author: Lennert Buytenhek <buytenh@wantstofly.org>
+.\"	Date:   Tue Jun 27 22:56:18 2006 +0100
+.\"
+.\" PTRACE_GETVFPREGS
+.\" PTRACE_SETVFPREGS
+.\"	ARM and ARM64
+.\"	Linux 2.6.30
+.\"	commit 3d1228ead618b88e8606015cbabc49019981805d
+.\"	Author: Catalin Marinas <catalin.marinas@arm.com>
+.\"	Date:   Wed Feb 11 13:12:56 2009 +0100
+.\"
+.\" PTRACE_GETHBPREGS
+.\" PTRACE_SETHBPREGS
+.\"	ARM and ARM64
+.\"	Linux 2.6.37
+.\"	commit 864232fa1a2f8dfe003438ef0851a56722740f3e
+.\"	Author: Will Deacon <will.deacon@arm.com>
+.\"	Date:   Fri Sep 3 10:42:55 2010 +0100
+.\"
+.\" PTRACE_SINGLEBLOCK
+.\"	Since at least Linux 2.4.0 on various architectures
+.\"	Since Linux 2.6.25 on x86 (and others?)
+.\"	commit 5b88abbf770a0e1975c668743100f42934f385e8
+.\"	Author: Roland McGrath <roland@redhat.com>
+.\"	Date:   Wed Jan 30 13:30:53 2008 +0100
+.\"	    ptrace: generic PTRACE_SINGLEBLOCK
+.\"
+.\" PTRACE_GETFPXREGS
+.\" PTRACE_SETFPXREGS
+.\"	Since at least Linux 2.4.0 on various architectures
+.\"
+.\" PTRACE_GETFDPIC
+.\" PTRACE_GETFDPIC_EXEC
+.\" PTRACE_GETFDPIC_INTERP
+.\"	blackfin, c6x, frv, sh
+.\"	First appearance in Linux 2.6.11 on frv
+.\"
+.\" and others that can be found in the arch/*/include/uapi/asm/ptrace files
+.\"
+.TH ptrace 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ptrace \- process trace
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/ptrace.h>
+.P
+.BI "long ptrace(enum __ptrace_request " op ", pid_t " pid ,
+.BI "            void *" addr ", void *" data );
+.fi
+.SH DESCRIPTION
+The
+.BR ptrace ()
+system call provides a means by which one process (the "tracer")
+may observe and control the execution of another process (the "tracee"),
+and examine and change the tracee's memory and registers.
+It is primarily used to implement breakpoint debugging and system
+call tracing.
+.P
+A tracee first needs to be attached to the tracer.
+Attachment and subsequent commands are per thread:
+in a multithreaded process,
+every thread can be individually attached to a
+(potentially different) tracer,
+or left not attached and thus not debugged.
+Therefore, "tracee" always means "(one) thread",
+never "a (possibly multithreaded) process".
+Ptrace commands are always sent to
+a specific tracee using a call of the form
+.P
+.in +4n
+.EX
+ptrace(PTRACE_foo, pid, ...)
+.EE
+.in
+.P
+where
+.I pid
+is the thread ID of the corresponding Linux thread.
+.P
+(Note that in this page, a "multithreaded process"
+means a thread group consisting of threads created using the
+.BR clone (2)
+.B CLONE_THREAD
+flag.)
+.P
+A process can initiate a trace by calling
+.BR fork (2)
+and having the resulting child do a
+.BR PTRACE_TRACEME ,
+followed (typically) by an
+.BR execve (2).
+Alternatively, one process may commence tracing another process using
+.B PTRACE_ATTACH
+or
+.BR PTRACE_SEIZE .
+.P
+While being traced, the tracee will stop each time a signal is delivered,
+even if the signal is being ignored.
+(An exception is
+.BR SIGKILL ,
+which has its usual effect.)
+The tracer will be notified at its next call to
+.BR waitpid (2)
+(or one of the related "wait" system calls); that call will return a
+.I status
+value containing information that indicates
+the cause of the stop in the tracee.
+While the tracee is stopped,
+the tracer can use various ptrace operations to inspect and modify the tracee.
+The tracer then causes the tracee to continue,
+optionally ignoring the delivered signal
+(or even delivering a different signal instead).
+.P
+If the
+.B PTRACE_O_TRACEEXEC
+option is not in effect, all successful calls to
+.BR execve (2)
+by the traced process will cause it to be sent a
+.B SIGTRAP
+signal,
+giving the parent a chance to gain control before the new program
+begins execution.
+.P
+When the tracer is finished tracing, it can cause the tracee to continue
+executing in a normal, untraced mode via
+.BR PTRACE_DETACH .
+.P
+The value of
+.I op
+determines the operation to be performed:
+.TP
+.B PTRACE_TRACEME
+Indicate that this process is to be traced by its parent.
+A process probably shouldn't make this operation if its parent
+isn't expecting to trace it.
+.RI ( pid ,
+.IR addr ,
+and
+.I data
+are ignored.)
+.IP
+The
+.B PTRACE_TRACEME
+operation is used only by the tracee;
+the remaining operations are used only by the tracer.
+In the following operations,
+.I pid
+specifies the thread ID of the tracee to be acted on.
+For operations other than
+.BR PTRACE_ATTACH ,
+.BR PTRACE_SEIZE ,
+.BR PTRACE_INTERRUPT ,
+and
+.BR PTRACE_KILL ,
+the tracee must be stopped.
+.TP
+.B PTRACE_PEEKTEXT
+.TQ
+.B PTRACE_PEEKDATA
+Read a word at the address
+.I addr
+in the tracee's memory, returning the word as the result of the
+.BR ptrace ()
+call.
+Linux does not have separate text and data address spaces,
+so these two operations are currently equivalent.
+.RI ( data
+is ignored; but see NOTES.)
+.TP
+.B PTRACE_PEEKUSER
+.\" PTRACE_PEEKUSR in kernel source, but glibc uses PTRACE_PEEKUSER,
+.\" and that is the name that seems common on other systems.
+Read a word at offset
+.I addr
+in the tracee's USER area,
+which holds the registers and other information about the process
+(see
+.IR <sys/user.h> ).
+The word is returned as the result of the
+.BR ptrace ()
+call.
+Typically, the offset must be word-aligned, though this might vary by
+architecture.
+See NOTES.
+.RI ( data
+is ignored; but see NOTES.)
+.TP
+.B PTRACE_POKETEXT
+.TQ
+.B PTRACE_POKEDATA
+Copy the word
+.I data
+to the address
+.I addr
+in the tracee's memory.
+As for
+.B PTRACE_PEEKTEXT
+and
+.BR PTRACE_PEEKDATA ,
+these two operations are currently equivalent.
+.TP
+.B PTRACE_POKEUSER
+.\" PTRACE_POKEUSR in kernel source, but glibc uses PTRACE_POKEUSER,
+.\" and that is the name that seems common on other systems.
+Copy the word
+.I data
+to offset
+.I addr
+in the tracee's USER area.
+As for
+.BR PTRACE_PEEKUSER ,
+the offset must typically be word-aligned.
+In order to maintain the integrity of the kernel,
+some modifications to the USER area are disallowed.
+.\" FIXME In the preceding sentence, which modifications are disallowed,
+.\" and when they are disallowed, how does user space discover that fact?
+.TP
+.B PTRACE_GETREGS
+.TQ
+.B PTRACE_GETFPREGS
+Copy the tracee's general-purpose or floating-point registers,
+respectively, to the address
+.I data
+in the tracer.
+See
+.I <sys/user.h>
+for information on the format of this data.
+.RI ( addr
+is ignored.)
+Note that SPARC systems have the meaning of
+.I data
+and
+.I addr
+reversed; that is,
+.I data
+is ignored and the registers are copied to the address
+.IR addr .
+.B PTRACE_GETREGS
+and
+.B PTRACE_GETFPREGS
+are not present on all architectures.
+.TP
+.BR PTRACE_GETREGSET " (since Linux 2.6.34)"
+Read the tracee's registers.
+.I addr
+specifies, in an architecture-dependent way, the type of registers to be read.
+.B NT_PRSTATUS
+(with numerical value 1)
+usually results in reading of general-purpose registers.
+If the CPU has, for example,
+floating-point and/or vector registers, they can be retrieved by setting
+.I addr
+to the corresponding
+.B NT_foo
+constant.
+.I data
+points to a
+.BR "struct iovec" ,
+which describes the destination buffer's location and length.
+On return, the kernel modifies
+.B iov.len
+to indicate the actual number of bytes returned.
+.TP
+.B PTRACE_SETREGS
+.TQ
+.B PTRACE_SETFPREGS
+Modify the tracee's general-purpose or floating-point registers,
+respectively, from the address
+.I data
+in the tracer.
+As for
+.BR PTRACE_POKEUSER ,
+some general-purpose register modifications may be disallowed.
+.\" FIXME . In the preceding sentence, which modifications are disallowed,
+.\" and when they are disallowed, how does user space discover that fact?
+.RI ( addr
+is ignored.)
+Note that SPARC systems have the meaning of
+.I data
+and
+.I addr
+reversed; that is,
+.I data
+is ignored and the registers are copied from the address
+.IR addr .
+.B PTRACE_SETREGS
+and
+.B PTRACE_SETFPREGS
+are not present on all architectures.
+.TP
+.BR PTRACE_SETREGSET " (since Linux 2.6.34)"
+Modify the tracee's registers.
+The meaning of
+.I addr
+and
+.I data
+is analogous to
+.BR PTRACE_GETREGSET .
+.TP
+.BR PTRACE_GETSIGINFO " (since Linux 2.3.99-pre6)"
+Retrieve information about the signal that caused the stop.
+Copy a
+.I siginfo_t
+structure (see
+.BR sigaction (2))
+from the tracee to the address
+.I data
+in the tracer.
+.RI ( addr
+is ignored.)
+.TP
+.BR PTRACE_SETSIGINFO " (since Linux 2.3.99-pre6)"
+Set signal information:
+copy a
+.I siginfo_t
+structure from the address
+.I data
+in the tracer to the tracee.
+This will affect only signals that would normally be delivered to
+the tracee and were caught by the tracer.
+It may be difficult to tell
+these normal signals from synthetic signals generated by
+.BR ptrace ()
+itself.
+.RI ( addr
+is ignored.)
+.TP
+.BR PTRACE_PEEKSIGINFO " (since Linux 3.10)"
+.\" commit 84c751bd4aebbaae995fe32279d3dba48327bad4
+Retrieve
+.I siginfo_t
+structures without removing signals from a queue.
+.I addr
+points to a
+.I ptrace_peeksiginfo_args
+structure that specifies the ordinal position from which
+copying of signals should start,
+and the number of signals to copy.
+.I siginfo_t
+structures are copied into the buffer pointed to by
+.IR data .
+The return value contains the number of copied signals (zero indicates
+that there is no signal corresponding to the specified ordinal position).
+Within the returned
+.I siginfo
+structures,
+the
+.I si_code
+field includes information
+.RB ( __SI_CHLD ,
+.BR __SI_FAULT ,
+etc.) that are not otherwise exposed to user space.
+.P
+.in +4n
+.EX
+struct ptrace_peeksiginfo_args {
+    u64 off;    /* Ordinal position in queue at which
+                   to start copying signals */
+    u32 flags;  /* PTRACE_PEEKSIGINFO_SHARED or 0 */
+    s32 nr;     /* Number of signals to copy */
+};
+.EE
+.in
+.IP
+Currently, there is only one flag,
+.BR PTRACE_PEEKSIGINFO_SHARED ,
+for dumping signals from the process-wide signal queue.
+If this flag is not set,
+signals are read from the per-thread queue of the specified thread.
+.in
+.TP
+.BR PTRACE_GETSIGMASK " (since Linux 3.11)"
+.\" commit 29000caecbe87b6b66f144f72111f0d02fbbf0c1
+Place a copy of the mask of blocked signals (see
+.BR sigprocmask (2))
+in the buffer pointed to by
+.IR data ,
+which should be a pointer to a buffer of type
+.IR sigset_t .
+The
+.I addr
+argument contains the size of the buffer pointed to by
+.I data
+(i.e.,
+.IR sizeof(sigset_t) ).
+.TP
+.BR PTRACE_SETSIGMASK " (since Linux 3.11)"
+Change the mask of blocked signals (see
+.BR sigprocmask (2))
+to the value specified in the buffer pointed to by
+.IR data ,
+which should be a pointer to a buffer of type
+.IR sigset_t .
+The
+.I addr
+argument contains the size of the buffer pointed to by
+.I data
+(i.e.,
+.IR sizeof(sigset_t) ).
+.TP
+.BR PTRACE_SETOPTIONS " (since Linux 2.4.6; see BUGS for caveats)"
+Set ptrace options from
+.IR data .
+.RI ( addr
+is ignored.)
+.I data
+is interpreted as a bit mask of options,
+which are specified by the following flags:
+.RS
+.TP
+.BR PTRACE_O_EXITKILL " (since Linux 3.8)"
+.\" commit 992fb6e170639b0849bace8e49bf31bd37c4123
+Send a
+.B SIGKILL
+signal to the tracee if the tracer exits.
+This option is useful for ptrace jailers that
+want to ensure that tracees can never escape the tracer's control.
+.TP
+.BR PTRACE_O_TRACECLONE " (since Linux 2.5.46)"
+Stop the tracee at the next
+.BR clone (2)
+and automatically start tracing the newly cloned process,
+which will start with a
+.BR SIGSTOP ,
+or
+.B PTRACE_EVENT_STOP
+if
+.B PTRACE_SEIZE
+was used.
+A
+.BR waitpid (2)
+by the tracer will return a
+.I status
+value such that
+.IP
+.nf
+  status>>8 == (SIGTRAP | (PTRACE_EVENT_CLONE<<8))
+.fi
+.IP
+The PID of the new process can be retrieved with
+.BR PTRACE_GETEVENTMSG .
+.IP
+This option may not catch
+.BR clone (2)
+calls in all cases.
+If the tracee calls
+.BR clone (2)
+with the
+.B CLONE_VFORK
+flag,
+.B PTRACE_EVENT_VFORK
+will be delivered instead
+if
+.B PTRACE_O_TRACEVFORK
+is set; otherwise if the tracee calls
+.BR clone (2)
+with the exit signal set to
+.BR SIGCHLD ,
+.B PTRACE_EVENT_FORK
+will be delivered if
+.B PTRACE_O_TRACEFORK
+is set.
+.TP
+.BR PTRACE_O_TRACEEXEC " (since Linux 2.5.46)"
+Stop the tracee at the next
+.BR execve (2).
+A
+.BR waitpid (2)
+by the tracer will return a
+.I status
+value such that
+.IP
+.nf
+  status>>8 == (SIGTRAP | (PTRACE_EVENT_EXEC<<8))
+.fi
+.IP
+If the execing thread is not a thread group leader,
+the thread ID is reset to thread group leader's ID before this stop.
+Since Linux 3.0, the former thread ID can be retrieved with
+.BR PTRACE_GETEVENTMSG .
+.TP
+.BR PTRACE_O_TRACEEXIT " (since Linux 2.5.60)"
+Stop the tracee at exit.
+A
+.BR waitpid (2)
+by the tracer will return a
+.I status
+value such that
+.IP
+.nf
+  status>>8 == (SIGTRAP | (PTRACE_EVENT_EXIT<<8))
+.fi
+.IP
+The tracee's exit status can be retrieved with
+.BR PTRACE_GETEVENTMSG .
+.IP
+The tracee is stopped early during process exit,
+when registers are still available,
+allowing the tracer to see where the exit occurred,
+whereas the normal exit notification is done after the process
+is finished exiting.
+Even though context is available,
+the tracer cannot prevent the exit from happening at this point.
+.TP
+.BR PTRACE_O_TRACEFORK " (since Linux 2.5.46)"
+Stop the tracee at the next
+.BR fork (2)
+and automatically start tracing the newly forked process,
+which will start with a
+.BR SIGSTOP ,
+or
+.B PTRACE_EVENT_STOP
+if
+.B PTRACE_SEIZE
+was used.
+A
+.BR waitpid (2)
+by the tracer will return a
+.I status
+value such that
+.IP
+.nf
+  status>>8 == (SIGTRAP | (PTRACE_EVENT_FORK<<8))
+.fi
+.IP
+The PID of the new process can be retrieved with
+.BR PTRACE_GETEVENTMSG .
+.TP
+.BR PTRACE_O_TRACESYSGOOD " (since Linux 2.4.6)"
+When delivering system call traps, set bit 7 in the signal number
+(i.e., deliver
+.IR "SIGTRAP|0x80" ).
+This makes it easy for the tracer to distinguish
+normal traps from those caused by a system call.
+.TP
+.BR PTRACE_O_TRACEVFORK " (since Linux 2.5.46)"
+Stop the tracee at the next
+.BR vfork (2)
+and automatically start tracing the newly vforked process,
+which will start with a
+.BR SIGSTOP ,
+or
+.B PTRACE_EVENT_STOP
+if
+.B PTRACE_SEIZE
+was used.
+A
+.BR waitpid (2)
+by the tracer will return a
+.I status
+value such that
+.IP
+.nf
+  status>>8 == (SIGTRAP | (PTRACE_EVENT_VFORK<<8))
+.fi
+.IP
+The PID of the new process can be retrieved with
+.BR PTRACE_GETEVENTMSG .
+.TP
+.BR PTRACE_O_TRACEVFORKDONE " (since Linux 2.5.60)"
+Stop the tracee at the completion of the next
+.BR vfork (2).
+A
+.BR waitpid (2)
+by the tracer will return a
+.I status
+value such that
+.IP
+.nf
+  status>>8 == (SIGTRAP | (PTRACE_EVENT_VFORK_DONE<<8))
+.fi
+.IP
+The PID of the new process can (since Linux 2.6.18) be retrieved with
+.BR PTRACE_GETEVENTMSG .
+.TP
+.BR PTRACE_O_TRACESECCOMP " (since Linux 3.5)"
+Stop the tracee when a
+.BR seccomp (2)
+.B SECCOMP_RET_TRACE
+rule is triggered.
+A
+.BR waitpid (2)
+by the tracer will return a
+.I status
+value such that
+.IP
+.nf
+  status>>8 == (SIGTRAP | (PTRACE_EVENT_SECCOMP<<8))
+.fi
+.IP
+While this triggers a
+.B PTRACE_EVENT
+stop, it is similar to a syscall-enter-stop.
+For details, see the note on
+.B PTRACE_EVENT_SECCOMP
+below.
+The seccomp event message data (from the
+.B SECCOMP_RET_DATA
+portion of the seccomp filter rule) can be retrieved with
+.BR PTRACE_GETEVENTMSG .
+.TP
+.BR PTRACE_O_SUSPEND_SECCOMP " (since Linux 4.3)"
+.\" commit 13c4a90119d28cfcb6b5bdd820c233b86c2b0237
+Suspend the tracee's seccomp protections.
+This applies regardless of mode, and
+can be used when the tracee has not yet installed seccomp filters.
+That is, a valid use case is to suspend a tracee's seccomp protections
+before they are installed by the tracee,
+let the tracee install the filters,
+and then clear this flag when the filters should be resumed.
+Setting this option requires that the tracer have the
+.B CAP_SYS_ADMIN
+capability,
+not have any seccomp protections installed, and not have
+.B PTRACE_O_SUSPEND_SECCOMP
+set on itself.
+.RE
+.TP
+.BR PTRACE_GETEVENTMSG " (since Linux 2.5.46)"
+Retrieve a message (as an
+.IR "unsigned long" )
+about the ptrace event
+that just happened, placing it at the address
+.I data
+in the tracer.
+For
+.BR PTRACE_EVENT_EXIT ,
+this is the tracee's exit status.
+For
+.BR PTRACE_EVENT_FORK ,
+.BR PTRACE_EVENT_VFORK ,
+.BR PTRACE_EVENT_VFORK_DONE ,
+and
+.BR PTRACE_EVENT_CLONE ,
+this is the PID of the new process.
+For
+.BR PTRACE_EVENT_SECCOMP ,
+this is the
+.BR seccomp (2)
+filter's
+.B SECCOMP_RET_DATA
+associated with the triggered rule.
+.RI ( addr
+is ignored.)
+.TP
+.B PTRACE_CONT
+Restart the stopped tracee process.
+If
+.I data
+is nonzero,
+it is interpreted as the number of a signal to be delivered to the tracee;
+otherwise, no signal is delivered.
+Thus, for example, the tracer can control
+whether a signal sent to the tracee is delivered or not.
+.RI ( addr
+is ignored.)
+.TP
+.B PTRACE_SYSCALL
+.TQ
+.B PTRACE_SINGLESTEP
+Restart the stopped tracee as for
+.BR PTRACE_CONT ,
+but arrange for the tracee to be stopped at
+the next entry to or exit from a system call,
+or after execution of a single instruction, respectively.
+(The tracee will also, as usual, be stopped upon receipt of a signal.)
+From the tracer's perspective, the tracee will appear to have been
+stopped by receipt of a
+.BR SIGTRAP .
+So, for
+.BR PTRACE_SYSCALL ,
+for example, the idea is to inspect
+the arguments to the system call at the first stop,
+then do another
+.B PTRACE_SYSCALL
+and inspect the return value of the system call at the second stop.
+The
+.I data
+argument is treated as for
+.BR PTRACE_CONT .
+.RI ( addr
+is ignored.)
+.TP
+.BR PTRACE_SET_SYSCALL " (since Linux 2.6.16)"
+.\" commit 3f471126ee53feb5e9b210ea2f525ed3bb9b7a7f
+When in syscall-enter-stop,
+change the number of the system call that is about to
+be executed to the number specified in the
+.I data
+argument.
+The
+.I addr
+argument is ignored.
+This operation is currently
+.\" As of 4.19-rc2
+supported only on arm (and arm64, though only for backwards compatibility),
+.\" commit 27aa55c5e5123fa8b8ad0156559d34d7edff58ca
+but most other architectures have other means of accomplishing this
+(usually by changing the register that the userland code passed the
+system call number in).
+.\" see change_syscall in tools/testing/selftests/seccomp/seccomp_bpf.c
+.\" and also strace's linux/*/set_scno.c files.
+.TP
+.B PTRACE_SYSEMU
+.TQ
+.BR PTRACE_SYSEMU_SINGLESTEP " (since Linux 2.6.14)"
+For
+.BR PTRACE_SYSEMU ,
+continue and stop on entry to the next system call,
+which will not be executed.
+See the documentation on syscall-stops below.
+For
+.BR PTRACE_SYSEMU_SINGLESTEP ,
+do the same but also singlestep if not a system call.
+This call is used by programs like
+User Mode Linux that want to emulate all the tracee's system calls.
+The
+.I data
+argument is treated as for
+.BR PTRACE_CONT .
+The
+.I addr
+argument is ignored.
+These operations are currently
+.\" As at 3.7
+supported only on x86.
+.TP
+.BR PTRACE_LISTEN " (since Linux 3.4)"
+Restart the stopped tracee, but prevent it from executing.
+The resulting state of the tracee is similar to a process which
+has been stopped by a
+.B SIGSTOP
+(or other stopping signal).
+See the "group-stop" subsection for additional information.
+.B PTRACE_LISTEN
+works only on tracees attached by
+.BR PTRACE_SEIZE .
+.TP
+.B PTRACE_KILL
+Send the tracee a
+.B SIGKILL
+to terminate it.
+.RI ( addr
+and
+.I data
+are ignored.)
+.IP
+.I This operation is deprecated; do not use it!
+Instead, send a
+.B SIGKILL
+directly using
+.BR kill (2)
+or
+.BR tgkill (2).
+The problem with
+.B PTRACE_KILL
+is that it requires the tracee to be in signal-delivery-stop,
+otherwise it may not work
+(i.e., may complete successfully but won't kill the tracee).
+By contrast, sending a
+.B SIGKILL
+directly has no such limitation.
+.\" [Note from Denys Vlasenko:
+.\"     deprecation suggested by Oleg Nesterov. He prefers to deprecate it
+.\"     instead of describing (and needing to support) PTRACE_KILL's quirks.]
+.TP
+.BR PTRACE_INTERRUPT " (since Linux 3.4)"
+Stop a tracee.
+If the tracee is running or sleeping in kernel space and
+.B PTRACE_SYSCALL
+is in effect,
+the system call is interrupted and syscall-exit-stop is reported.
+(The interrupted system call is restarted when the tracee is restarted.)
+If the tracee was already stopped by a signal and
+.B PTRACE_LISTEN
+was sent to it,
+the tracee stops with
+.B PTRACE_EVENT_STOP
+and
+.I WSTOPSIG(status)
+returns the stop signal.
+If any other ptrace-stop is generated at the same time (for example,
+if a signal is sent to the tracee), this ptrace-stop happens.
+If none of the above applies (for example, if the tracee is running in user
+space), it stops with
+.B PTRACE_EVENT_STOP
+with
+.I WSTOPSIG(status)
+==
+.BR SIGTRAP .
+.B PTRACE_INTERRUPT
+only works on tracees attached by
+.BR PTRACE_SEIZE .
+.TP
+.B PTRACE_ATTACH
+Attach to the process specified in
+.IR pid ,
+making it a tracee of the calling process.
+.\" No longer true (removed by Denys Vlasenko, 2011, who remarks:
+.\"        "I think it isn't true in non-ancient 2.4 and in Linux 2.6/3.x.
+.\"         Basically, it's not true for any Linux in practical use.
+.\" ; the behavior of the tracee is as if it had done a
+.\" .BR PTRACE_TRACEME .
+.\" The calling process actually becomes the parent of the tracee
+.\" process for most purposes (e.g., it will receive
+.\" notification of tracee events and appears in
+.\" .BR ps (1)
+.\" output as the tracee's parent), but a
+.\" .BR getppid (2)
+.\" by the tracee will still return the PID of the original parent.
+The tracee is sent a
+.BR SIGSTOP ,
+but will not necessarily have stopped
+by the completion of this call; use
+.BR waitpid (2)
+to wait for the tracee to stop.
+See the "Attaching and detaching" subsection for additional information.
+.RI ( addr
+and
+.I data
+are ignored.)
+.IP
+Permission to perform a
+.B PTRACE_ATTACH
+is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_REALCREDS
+check; see below.
+.TP
+.BR PTRACE_SEIZE " (since Linux 3.4)"
+.\"
+.\" Noted by Dmitry Levin:
+.\"
+.\"     PTRACE_SEIZE was introduced by commit v3.1-rc1~308^2~28, but
+.\"     it had to be used along with a temporary flag PTRACE_SEIZE_DEVEL,
+.\"     which was removed later by commit v3.4-rc1~109^2~20.
+.\"
+.\"     That is, [before] v3.4 we had a test mode of PTRACE_SEIZE API,
+.\"     which was not compatible with the current PTRACE_SEIZE API introduced
+.\"     in Linux 3.4.
+.\"
+Attach to the process specified in
+.IR pid ,
+making it a tracee of the calling process.
+Unlike
+.BR PTRACE_ATTACH ,
+.B PTRACE_SEIZE
+does not stop the process.
+Group-stops are reported as
+.B PTRACE_EVENT_STOP
+and
+.I WSTOPSIG(status)
+returns the stop signal.
+Automatically attached children stop with
+.B PTRACE_EVENT_STOP
+and
+.I WSTOPSIG(status)
+returns
+.B SIGTRAP
+instead of having
+.B SIGSTOP
+signal delivered to them.
+.BR execve (2)
+does not deliver an extra
+.BR SIGTRAP .
+Only a
+.BR PTRACE_SEIZE d
+process can accept
+.B PTRACE_INTERRUPT
+and
+.B PTRACE_LISTEN
+commands.
+The "seized" behavior just described is inherited by
+children that are automatically attached using
+.BR PTRACE_O_TRACEFORK ,
+.BR PTRACE_O_TRACEVFORK ,
+and
+.BR PTRACE_O_TRACECLONE .
+.I addr
+must be zero.
+.I data
+contains a bit mask of ptrace options to activate immediately.
+.IP
+Permission to perform a
+.B PTRACE_SEIZE
+is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_REALCREDS
+check; see below.
+.\"
+.TP
+.BR PTRACE_SECCOMP_GET_FILTER " (since Linux 4.4)"
+.\" commit f8e529ed941ba2bbcbf310b575d968159ce7e895
+This operation allows the tracer to dump the tracee's
+classic BPF filters.
+.IP
+.I addr
+is an integer specifying the index of the filter to be dumped.
+The most recently installed filter has the index 0.
+If
+.I addr
+is greater than the number of installed filters,
+the operation fails with the error
+.BR ENOENT .
+.IP
+.I data
+is either a pointer to a
+.I struct sock_filter
+array that is large enough to store the BPF program,
+or NULL if the program is not to be stored.
+.IP
+Upon success,
+the return value is the number of instructions in the BPF program.
+If
+.I data
+was NULL, then this return value can be used to correctly size the
+.I struct sock_filter
+array passed in a subsequent call.
+.IP
+This operation fails with the error
+.B EACCES
+if the caller does not have the
+.B CAP_SYS_ADMIN
+capability or if the caller is in strict or filter seccomp mode.
+If the filter referred to by
+.I addr
+is not a classic BPF filter, the operation fails with the error
+.BR EMEDIUMTYPE .
+.IP
+This operation is available if the kernel was configured with both the
+.B CONFIG_SECCOMP_FILTER
+and the
+.B CONFIG_CHECKPOINT_RESTORE
+options.
+.TP
+.B PTRACE_DETACH
+Restart the stopped tracee as for
+.BR PTRACE_CONT ,
+but first detach from it.
+Under Linux, a tracee can be detached in this way regardless
+of which method was used to initiate tracing.
+.RI ( addr
+is ignored.)
+.\"
+.TP
+.BR PTRACE_GET_THREAD_AREA " (since Linux 2.6.0)"
+This operation performs a similar task to
+.BR get_thread_area (2).
+It reads the TLS entry in the GDT whose index is given in
+.IR addr ,
+placing a copy of the entry into the
+.I struct user_desc
+pointed to by
+.IR data .
+(By contrast with
+.BR get_thread_area (2),
+the
+.I entry_number
+of the
+.I struct user_desc
+is ignored.)
+.TP
+.BR PTRACE_SET_THREAD_AREA " (since Linux 2.6.0)"
+This operation performs a similar task to
+.BR set_thread_area (2).
+It sets the TLS entry in the GDT whose index is given in
+.IR addr ,
+assigning it the data supplied in the
+.I struct user_desc
+pointed to by
+.IR data .
+(By contrast with
+.BR set_thread_area (2),
+the
+.I entry_number
+of the
+.I struct user_desc
+is ignored; in other words,
+this ptrace operation can't be used to allocate a free TLS entry.)
+.TP
+.BR PTRACE_GET_SYSCALL_INFO " (since Linux 5.3)"
+.\" commit 201766a20e30f982ccfe36bebfad9602c3ff574a
+Retrieve information about the system call that caused the stop.
+The information is placed into the buffer pointed by the
+.I data
+argument, which should be a pointer to a buffer of type
+.IR "struct ptrace_syscall_info" .
+The
+.I addr
+argument contains the size of the buffer pointed to
+by the
+.I data
+argument (i.e.,
+.IR "sizeof(struct ptrace_syscall_info)" ).
+The return value contains the number of bytes available
+to be written by the kernel.
+If the size of the data to be written by the kernel exceeds the size
+specified by the
+.I addr
+argument, the output data is truncated.
+.IP
+The
+.I ptrace_syscall_info
+structure contains the following fields:
+.IP
+.in +4n
+.EX
+struct ptrace_syscall_info {
+    __u8 op;        /* Type of system call stop */
+    __u32 arch;     /* AUDIT_ARCH_* value; see seccomp(2) */
+    __u64 instruction_pointer; /* CPU instruction pointer */
+    __u64 stack_pointer;    /* CPU stack pointer */
+    union {
+        struct {    /* op == PTRACE_SYSCALL_INFO_ENTRY */
+            __u64 nr;       /* System call number */
+            __u64 args[6];  /* System call arguments */
+        } entry;
+        struct {    /* op == PTRACE_SYSCALL_INFO_EXIT */
+            __s64 rval;     /* System call return value */
+            __u8 is_error;  /* System call error flag;
+                               Boolean: does rval contain
+                               an error value (\-ERRCODE) or
+                               a nonerror return value? */
+        } exit;
+        struct {    /* op == PTRACE_SYSCALL_INFO_SECCOMP */
+            __u64 nr;       /* System call number */
+            __u64 args[6];  /* System call arguments */
+            __u32 ret_data; /* SECCOMP_RET_DATA portion
+                               of SECCOMP_RET_TRACE
+                               return value */
+        } seccomp;
+    };
+};
+.EE
+.in
+.IP
+The
+.IR op ,
+.IR arch ,
+.IR instruction_pointer ,
+and
+.I stack_pointer
+fields are defined for all kinds of ptrace system call stops.
+The rest of the structure is a union; one should read only those fields
+that are meaningful for the kind of system call stop specified by the
+.I op
+field.
+.IP
+The
+.I op
+field has one of the following values (defined in
+.IR <linux/ptrace.h> )
+indicating what type of stop occurred and
+which part of the union is filled:
+.RS
+.TP
+.B PTRACE_SYSCALL_INFO_ENTRY
+The
+.I entry
+component of the union contains information relating to a
+system call entry stop.
+.TP
+.B PTRACE_SYSCALL_INFO_EXIT
+The
+.I exit
+component of the union contains information relating to a
+system call exit stop.
+.TP
+.B PTRACE_SYSCALL_INFO_SECCOMP
+The
+.I seccomp
+component of the union contains information relating to a
+.B PTRACE_EVENT_SECCOMP
+stop.
+.TP
+.B PTRACE_SYSCALL_INFO_NONE
+No component of the union contains relevant information.
+.RE
+.IP
+In case of system call entry or exit stops,
+the data returned by
+.B PTRACE_GET_SYSCALL_INFO
+is limited to type
+.B PTRACE_SYSCALL_INFO_NONE
+unless
+.B PTRACE_O_TRACESYSGOOD
+option is set before the corresponding system call stop has occurred.
+.\"
+.SS Death under ptrace
+When a (possibly multithreaded) process receives a killing signal
+(one whose disposition is set to
+.B SIG_DFL
+and whose default action is to kill the process),
+all threads exit.
+Tracees report their death to their tracer(s).
+Notification of this event is delivered via
+.BR waitpid (2).
+.P
+Note that the killing signal will first cause signal-delivery-stop
+(on one tracee only),
+and only after it is injected by the tracer
+(or after it was dispatched to a thread which isn't traced),
+will death from the signal happen on
+.I all
+tracees within a multithreaded process.
+(The term "signal-delivery-stop" is explained below.)
+.P
+.B SIGKILL
+does not generate signal-delivery-stop and
+therefore the tracer can't suppress it.
+.B SIGKILL
+kills even within system calls
+(syscall-exit-stop is not generated prior to death by
+.BR SIGKILL ).
+The net effect is that
+.B SIGKILL
+always kills the process (all its threads),
+even if some threads of the process are ptraced.
+.P
+When the tracee calls
+.BR _exit (2),
+it reports its death to its tracer.
+Other threads are not affected.
+.P
+When any thread executes
+.BR exit_group (2),
+every tracee in its thread group reports its death to its tracer.
+.P
+If the
+.B PTRACE_O_TRACEEXIT
+option is on,
+.B PTRACE_EVENT_EXIT
+will happen before actual death.
+This applies to exits via
+.BR exit (2),
+.BR exit_group (2),
+and signal deaths (except
+.BR SIGKILL ,
+depending on the kernel version; see BUGS below),
+and when threads are torn down on
+.BR execve (2)
+in a multithreaded process.
+.P
+The tracer cannot assume that the ptrace-stopped tracee exists.
+There are many scenarios when the tracee may die while stopped (such as
+.BR SIGKILL ).
+Therefore, the tracer must be prepared to handle an
+.B ESRCH
+error on any ptrace operation.
+Unfortunately, the same error is returned if the tracee
+exists but is not ptrace-stopped
+(for commands which require a stopped tracee),
+or if it is not traced by the process which issued the ptrace call.
+The tracer needs to keep track of the stopped/running state of the tracee,
+and interpret
+.B ESRCH
+as "tracee died unexpectedly" only if it knows that the tracee has
+been observed to enter ptrace-stop.
+Note that there is no guarantee that
+.I waitpid(WNOHANG)
+will reliably report the tracee's death status if a
+ptrace operation returned
+.BR ESRCH .
+.I waitpid(WNOHANG)
+may return 0 instead.
+In other words, the tracee may be "not yet fully dead",
+but already refusing ptrace operations.
+.P
+The tracer can't assume that the tracee
+.I always
+ends its life by reporting
+.I WIFEXITED(status)
+or
+.IR WIFSIGNALED(status) ;
+there are cases where this does not occur.
+For example, if a thread other than thread group leader does an
+.BR execve (2),
+it disappears;
+its PID will never be seen again,
+and any subsequent ptrace stops will be reported under
+the thread group leader's PID.
+.SS Stopped states
+A tracee can be in two states: running or stopped.
+For the purposes of ptrace, a tracee which is blocked in a system call
+(such as
+.BR read (2),
+.BR pause (2),
+etc.)
+is nevertheless considered to be running, even if the tracee is blocked
+for a long time.
+The state of the tracee after
+.B PTRACE_LISTEN
+is somewhat of a gray area: it is not in any ptrace-stop (ptrace commands
+won't work on it, and it will deliver
+.BR waitpid (2)
+notifications),
+but it also may be considered "stopped" because
+it is not executing instructions (is not scheduled), and if it was
+in group-stop before
+.BR PTRACE_LISTEN ,
+it will not respond to signals until
+.B SIGCONT
+is received.
+.P
+There are many kinds of states when the tracee is stopped, and in ptrace
+discussions they are often conflated.
+Therefore, it is important to use precise terms.
+.P
+In this manual page, any stopped state in which the tracee is ready
+to accept ptrace commands from the tracer is called
+.IR ptrace-stop .
+Ptrace-stops can
+be further subdivided into
+.IR signal-delivery-stop ,
+.IR group-stop ,
+.IR syscall-stop ,
+.IR "PTRACE_EVENT stops" ,
+and so on.
+These stopped states are described in detail below.
+.P
+When the running tracee enters ptrace-stop, it notifies its tracer using
+.BR waitpid (2)
+(or one of the other "wait" system calls).
+Most of this manual page assumes that the tracer waits with:
+.P
+.in +4n
+.EX
+pid = waitpid(pid_or_minus_1, &status, __WALL);
+.EE
+.in
+.P
+Ptrace-stopped tracees are reported as returns with
+.I pid
+greater than 0 and
+.I WIFSTOPPED(status)
+true.
+.\" Denys Vlasenko:
+.\"     Do we require __WALL usage, or will just using 0 be ok? (With 0,
+.\"     I am not 100% sure there aren't ugly corner cases.) Are the
+.\"     rules different if user wants to use waitid? Will waitid require
+.\"     WEXITED?
+.\"
+.P
+The
+.B __WALL
+flag does not include the
+.B WSTOPPED
+and
+.B WEXITED
+flags, but implies their functionality.
+.P
+Setting the
+.B WCONTINUED
+flag when calling
+.BR waitpid (2)
+is not recommended: the "continued" state is per-process and
+consuming it can confuse the real parent of the tracee.
+.P
+Use of the
+.B WNOHANG
+flag may cause
+.BR waitpid (2)
+to return 0 ("no wait results available yet")
+even if the tracer knows there should be a notification.
+Example:
+.P
+.in +4n
+.EX
+errno = 0;
+ptrace(PTRACE_CONT, pid, 0L, 0L);
+if (errno == ESRCH) {
+    /* tracee is dead */
+    r = waitpid(tracee, &status, __WALL | WNOHANG);
+    /* r can still be 0 here! */
+}
+.EE
+.in
+.\" FIXME .
+.\"     waitid usage? WNOWAIT?
+.\"     describe how wait notifications queue (or not queue)
+.P
+The following kinds of ptrace-stops exist: signal-delivery-stops,
+group-stops,
+.B PTRACE_EVENT
+stops, syscall-stops.
+They all are reported by
+.BR waitpid (2)
+with
+.I WIFSTOPPED(status)
+true.
+They may be differentiated by examining the value
+.IR status>>8 ,
+and if there is ambiguity in that value, by querying
+.BR PTRACE_GETSIGINFO .
+(Note: the
+.I WSTOPSIG(status)
+macro can't be used to perform this examination,
+because it returns the value
+.IR "(status>>8)\ &\ 0xff" .)
+.SS Signal-delivery-stop
+When a (possibly multithreaded) process receives any signal except
+.BR SIGKILL ,
+the kernel selects an arbitrary thread which handles the signal.
+(If the signal is generated with
+.BR tgkill (2),
+the target thread can be explicitly selected by the caller.)
+If the selected thread is traced, it enters signal-delivery-stop.
+At this point, the signal is not yet delivered to the process,
+and can be suppressed by the tracer.
+If the tracer doesn't suppress the signal,
+it passes the signal to the tracee in the next ptrace restart operation.
+This second step of signal delivery is called
+.I "signal injection"
+in this manual page.
+Note that if the signal is blocked,
+signal-delivery-stop doesn't happen until the signal is unblocked,
+with the usual exception that
+.B SIGSTOP
+can't be blocked.
+.P
+Signal-delivery-stop is observed by the tracer as
+.BR waitpid (2)
+returning with
+.I WIFSTOPPED(status)
+true, with the signal returned by
+.IR WSTOPSIG(status) .
+If the signal is
+.BR SIGTRAP ,
+this may be a different kind of ptrace-stop;
+see the "Syscall-stops" and "execve" sections below for details.
+If
+.I WSTOPSIG(status)
+returns a stopping signal, this may be a group-stop; see below.
+.SS Signal injection and suppression
+After signal-delivery-stop is observed by the tracer,
+the tracer should restart the tracee with the call
+.P
+.in +4n
+.EX
+ptrace(PTRACE_restart, pid, 0, sig)
+.EE
+.in
+.P
+where
+.B PTRACE_restart
+is one of the restarting ptrace operations.
+If
+.I sig
+is 0, then a signal is not delivered.
+Otherwise, the signal
+.I sig
+is delivered.
+This operation is called
+.I "signal injection"
+in this manual page, to distinguish it from signal-delivery-stop.
+.P
+The
+.I sig
+value may be different from the
+.I WSTOPSIG(status)
+value: the tracer can cause a different signal to be injected.
+.P
+Note that a suppressed signal still causes system calls to return
+prematurely.
+In this case, system calls will be restarted: the tracer will
+observe the tracee to reexecute the interrupted system call (or
+.BR restart_syscall (2)
+system call for a few system calls which use a different mechanism
+for restarting) if the tracer uses
+.BR PTRACE_SYSCALL .
+Even system calls (such as
+.BR poll (2))
+which are not restartable after signal are restarted after
+signal is suppressed;
+however, kernel bugs exist which cause some system calls to fail with
+.B EINTR
+even though no observable signal is injected to the tracee.
+.P
+Restarting ptrace commands issued in ptrace-stops other than
+signal-delivery-stop are not guaranteed to inject a signal, even if
+.I sig
+is nonzero.
+No error is reported; a nonzero
+.I sig
+may simply be ignored.
+Ptrace users should not try to "create a new signal" this way: use
+.BR tgkill (2)
+instead.
+.P
+The fact that signal injection operations may be ignored
+when restarting the tracee after
+ptrace stops that are not signal-delivery-stops
+is a cause of confusion among ptrace users.
+One typical scenario is that the tracer observes group-stop,
+mistakes it for signal-delivery-stop, restarts the tracee with
+.P
+.in +4n
+.EX
+ptrace(PTRACE_restart, pid, 0, stopsig)
+.EE
+.in
+.P
+with the intention of injecting
+.IR stopsig ,
+but
+.I stopsig
+gets ignored and the tracee continues to run.
+.P
+The
+.B SIGCONT
+signal has a side effect of waking up (all threads of)
+a group-stopped process.
+This side effect happens before signal-delivery-stop.
+The tracer can't suppress this side effect (it can
+only suppress signal injection, which only causes the
+.B SIGCONT
+handler to not be executed in the tracee, if such a handler is installed).
+In fact, waking up from group-stop may be followed by
+signal-delivery-stop for signal(s)
+.I other than
+.BR SIGCONT ,
+if they were pending when
+.B SIGCONT
+was delivered.
+In other words,
+.B SIGCONT
+may be not the first signal observed by the tracee after it was sent.
+.P
+Stopping signals cause (all threads of) a process to enter group-stop.
+This side effect happens after signal injection, and therefore can be
+suppressed by the tracer.
+.P
+In Linux 2.4 and earlier, the
+.B SIGSTOP
+signal can't be injected.
+.\" In the Linux 2.4 sources, in arch/i386/kernel/signal.c::do_signal(),
+.\" there is:
+.\"
+.\"             /* The debugger continued.  Ignore SIGSTOP.  */
+.\"             if (signr == SIGSTOP)
+.\"                     continue;
+.P
+.B PTRACE_GETSIGINFO
+can be used to retrieve a
+.I siginfo_t
+structure which corresponds to the delivered signal.
+.B PTRACE_SETSIGINFO
+may be used to modify it.
+If
+.B PTRACE_SETSIGINFO
+has been used to alter
+.IR siginfo_t ,
+the
+.I si_signo
+field and the
+.I sig
+parameter in the restarting command must match,
+otherwise the result is undefined.
+.SS Group-stop
+When a (possibly multithreaded) process receives a stopping signal,
+all threads stop.
+If some threads are traced, they enter a group-stop.
+Note that the stopping signal will first cause signal-delivery-stop
+(on one tracee only), and only after it is injected by the tracer
+(or after it was dispatched to a thread which isn't traced),
+will group-stop be initiated on
+.I all
+tracees within the multithreaded process.
+As usual, every tracee reports its group-stop separately
+to the corresponding tracer.
+.P
+Group-stop is observed by the tracer as
+.BR waitpid (2)
+returning with
+.I WIFSTOPPED(status)
+true, with the stopping signal available via
+.IR WSTOPSIG(status) .
+The same result is returned by some other classes of ptrace-stops,
+therefore the recommended practice is to perform the call
+.P
+.in +4n
+.EX
+ptrace(PTRACE_GETSIGINFO, pid, 0, &siginfo)
+.EE
+.in
+.P
+The call can be avoided if the signal is not
+.BR SIGSTOP ,
+.BR SIGTSTP ,
+.BR SIGTTIN ,
+or
+.BR SIGTTOU ;
+only these four signals are stopping signals.
+If the tracer sees something else, it can't be a group-stop.
+Otherwise, the tracer needs to call
+.BR PTRACE_GETSIGINFO .
+If
+.B PTRACE_GETSIGINFO
+fails with
+.BR EINVAL ,
+then it is definitely a group-stop.
+(Other failure codes are possible, such as
+.B ESRCH
+("no such process") if a
+.B SIGKILL
+killed the tracee.)
+.P
+If tracee was attached using
+.BR PTRACE_SEIZE ,
+group-stop is indicated by
+.BR PTRACE_EVENT_STOP :
+.IR "status>>16 == PTRACE_EVENT_STOP" .
+This allows detection of group-stops
+without requiring an extra
+.B PTRACE_GETSIGINFO
+call.
+.P
+As of Linux 2.6.38,
+after the tracer sees the tracee ptrace-stop and until it
+restarts or kills it, the tracee will not run,
+and will not send notifications (except
+.B SIGKILL
+death) to the tracer, even if the tracer enters into another
+.BR waitpid (2)
+call.
+.P
+The kernel behavior described in the previous paragraph
+causes a problem with transparent handling of stopping signals.
+If the tracer restarts the tracee after group-stop,
+the stopping signal
+is effectively ignored\[em]the tracee doesn't remain stopped, it runs.
+If the tracer doesn't restart the tracee before entering into the next
+.BR waitpid (2),
+future
+.B SIGCONT
+signals will not be reported to the tracer;
+this would cause the
+.B SIGCONT
+signals to have no effect on the tracee.
+.P
+Since Linux 3.4, there is a method to overcome this problem: instead of
+.BR PTRACE_CONT ,
+a
+.B PTRACE_LISTEN
+command can be used to restart a tracee in a way where it does not execute,
+but waits for a new event which it can report via
+.BR waitpid (2)
+(such as when
+it is restarted by a
+.BR SIGCONT ).
+.SS PTRACE_EVENT stops
+If the tracer sets
+.B PTRACE_O_TRACE_*
+options, the tracee will enter ptrace-stops called
+.B PTRACE_EVENT
+stops.
+.P
+.B PTRACE_EVENT
+stops are observed by the tracer as
+.BR waitpid (2)
+returning with
+.IR WIFSTOPPED(status) ,
+and
+.I WSTOPSIG(status)
+returns
+.B SIGTRAP
+(or for
+.BR PTRACE_EVENT_STOP ,
+returns the stopping signal if tracee is in a group-stop).
+An additional bit is set in the higher byte of the status word:
+the value
+.I status>>8
+will be
+.P
+.in +4n
+.EX
+((PTRACE_EVENT_foo<<8) | SIGTRAP).
+.EE
+.in
+.P
+The following events exist:
+.TP
+.B PTRACE_EVENT_VFORK
+Stop before return from
+.BR vfork (2)
+or
+.BR clone (2)
+with the
+.B CLONE_VFORK
+flag.
+When the tracee is continued after this stop, it will wait for child to
+exit/exec before continuing its execution
+(in other words, the usual behavior on
+.BR vfork (2)).
+.TP
+.B PTRACE_EVENT_FORK
+Stop before return from
+.BR fork (2)
+or
+.BR clone (2)
+with the exit signal set to
+.BR SIGCHLD .
+.TP
+.B PTRACE_EVENT_CLONE
+Stop before return from
+.BR clone (2).
+.TP
+.B PTRACE_EVENT_VFORK_DONE
+Stop before return from
+.BR vfork (2)
+or
+.BR clone (2)
+with the
+.B CLONE_VFORK
+flag,
+but after the child unblocked this tracee by exiting or execing.
+.P
+For all four stops described above,
+the stop occurs in the parent (i.e., the tracee),
+not in the newly created thread.
+.B PTRACE_GETEVENTMSG
+can be used to retrieve the new thread's ID.
+.TP
+.B PTRACE_EVENT_EXEC
+Stop before return from
+.BR execve (2).
+Since Linux 3.0,
+.B PTRACE_GETEVENTMSG
+returns the former thread ID.
+.TP
+.B PTRACE_EVENT_EXIT
+Stop before exit (including death from
+.BR exit_group (2)),
+signal death, or exit caused by
+.BR execve (2)
+in a multithreaded process.
+.B PTRACE_GETEVENTMSG
+returns the exit status.
+Registers can be examined
+(unlike when "real" exit happens).
+The tracee is still alive; it needs to be
+.BR PTRACE_CONT ed
+or
+.BR PTRACE_DETACH ed
+to finish exiting.
+.TP
+.B PTRACE_EVENT_STOP
+Stop induced by
+.B PTRACE_INTERRUPT
+command, or group-stop, or initial ptrace-stop when a new child is attached
+(only if attached using
+.BR PTRACE_SEIZE ).
+.TP
+.B PTRACE_EVENT_SECCOMP
+Stop triggered by a
+.BR seccomp (2)
+rule on tracee syscall entry when
+.B PTRACE_O_TRACESECCOMP
+has been set by the tracer.
+The seccomp event message data (from the
+.B SECCOMP_RET_DATA
+portion of the seccomp filter rule) can be retrieved with
+.BR PTRACE_GETEVENTMSG .
+The semantics of this stop are described in
+detail in a separate section below.
+.P
+.B PTRACE_GETSIGINFO
+on
+.B PTRACE_EVENT
+stops returns
+.B SIGTRAP
+in
+.IR si_signo ,
+with
+.I si_code
+set to
+.IR "(event<<8)\ |\ SIGTRAP" .
+.SS Syscall-stops
+If the tracee was restarted by
+.B PTRACE_SYSCALL
+or
+.BR PTRACE_SYSEMU ,
+the tracee enters
+syscall-enter-stop just prior to entering any system call (which
+will not be executed if the restart was using
+.BR PTRACE_SYSEMU ,
+regardless of any change made to registers at this point or how the
+tracee is restarted after this stop).
+No matter which method caused the syscall-entry-stop,
+if the tracer restarts the tracee with
+.BR PTRACE_SYSCALL ,
+the tracee enters syscall-exit-stop when the system call is finished,
+or if it is interrupted by a signal.
+(That is, signal-delivery-stop never happens between syscall-enter-stop
+and syscall-exit-stop; it happens
+.I after
+syscall-exit-stop.).
+If the tracee is continued using any other method (including
+.BR PTRACE_SYSEMU ),
+no syscall-exit-stop occurs.
+Note that all mentions
+.B PTRACE_SYSEMU
+apply equally to
+.BR PTRACE_SYSEMU_SINGLESTEP .
+.P
+However, even if the tracee was continued using
+.BR PTRACE_SYSCALL ,
+it is not guaranteed that the next stop will be a syscall-exit-stop.
+Other possibilities are that the tracee may stop in a
+.B PTRACE_EVENT
+stop (including seccomp stops), exit (if it entered
+.BR _exit (2)
+or
+.BR exit_group (2)),
+be killed by
+.BR SIGKILL ,
+or die silently (if it is a thread group leader, the
+.BR execve (2)
+happened in another thread,
+and that thread is not traced by the same tracer;
+this situation is discussed later).
+.P
+Syscall-enter-stop and syscall-exit-stop are observed by the tracer as
+.BR waitpid (2)
+returning with
+.I WIFSTOPPED(status)
+true, and
+.I WSTOPSIG(status)
+giving
+.BR SIGTRAP .
+If the
+.B PTRACE_O_TRACESYSGOOD
+option was set by the tracer, then
+.I WSTOPSIG(status)
+will give the value
+.IR "(SIGTRAP\ |\ 0x80)" .
+.P
+Syscall-stops can be distinguished from signal-delivery-stop with
+.B SIGTRAP
+by querying
+.B PTRACE_GETSIGINFO
+for the following cases:
+.TP
+.IR si_code " <= 0"
+.B SIGTRAP
+was delivered as a result of a user-space action,
+for example, a system call
+.RB ( tgkill (2),
+.BR kill (2),
+.BR sigqueue (3),
+etc.),
+expiration of a POSIX timer,
+change of state on a POSIX message queue,
+or completion of an asynchronous I/O operation.
+.TP
+.IR si_code " == SI_KERNEL (0x80)"
+.B SIGTRAP
+was sent by the kernel.
+.TP
+.IR si_code " == SIGTRAP or " si_code " == (SIGTRAP|0x80)"
+This is a syscall-stop.
+.P
+However, syscall-stops happen very often (twice per system call),
+and performing
+.B PTRACE_GETSIGINFO
+for every syscall-stop may be somewhat expensive.
+.P
+Some architectures allow the cases to be distinguished
+by examining registers.
+For example, on x86,
+.I rax
+==
+.RB \- ENOSYS
+in syscall-enter-stop.
+Since
+.B SIGTRAP
+(like any other signal) always happens
+.I after
+syscall-exit-stop,
+and at this point
+.I rax
+almost never contains
+.RB \- ENOSYS ,
+the
+.B SIGTRAP
+looks like "syscall-stop which is not syscall-enter-stop";
+in other words, it looks like a
+"stray syscall-exit-stop" and can be detected this way.
+But such detection is fragile and is best avoided.
+.P
+Using the
+.B PTRACE_O_TRACESYSGOOD
+option is the recommended method to distinguish syscall-stops
+from other kinds of ptrace-stops,
+since it is reliable and does not incur a performance penalty.
+.P
+Syscall-enter-stop and syscall-exit-stop are
+indistinguishable from each other by the tracer.
+The tracer needs to keep track of the sequence of
+ptrace-stops in order to not misinterpret syscall-enter-stop as
+syscall-exit-stop or vice versa.
+In general, a syscall-enter-stop is
+always followed by syscall-exit-stop,
+.B PTRACE_EVENT
+stop, or the tracee's death;
+no other kinds of ptrace-stop can occur in between.
+However, note that seccomp stops (see below) can cause syscall-exit-stops,
+without preceding syscall-entry-stops.
+If seccomp is in use, care needs
+to be taken not to misinterpret such stops as syscall-entry-stops.
+.P
+If after syscall-enter-stop,
+the tracer uses a restarting command other than
+.BR PTRACE_SYSCALL ,
+syscall-exit-stop is not generated.
+.P
+.B PTRACE_GETSIGINFO
+on syscall-stops returns
+.B SIGTRAP
+in
+.IR si_signo ,
+with
+.I si_code
+set to
+.B SIGTRAP
+or
+.IR (SIGTRAP|0x80) .
+.\"
+.SS PTRACE_EVENT_SECCOMP stops (Linux 3.5 to Linux 4.7)
+The behavior of
+.B PTRACE_EVENT_SECCOMP
+stops and their interaction with other kinds
+of ptrace stops has changed between kernel versions.
+This documents the behavior
+from their introduction until Linux 4.7 (inclusive).
+The behavior in later kernel versions is documented in the next section.
+.P
+A
+.B PTRACE_EVENT_SECCOMP
+stop occurs whenever a
+.B SECCOMP_RET_TRACE
+rule is triggered.
+This is independent of which methods was used to restart the system call.
+Notably, seccomp still runs even if the tracee was restarted using
+.B PTRACE_SYSEMU
+and this system call is unconditionally skipped.
+.P
+Restarts from this stop will behave as if the stop had occurred right
+before the system call in question.
+In particular, both
+.B PTRACE_SYSCALL
+and
+.B PTRACE_SYSEMU
+will normally cause a subsequent syscall-entry-stop.
+However, if after the
+.B PTRACE_EVENT_SECCOMP
+the system call number is negative,
+both the syscall-entry-stop and the system call itself will be skipped.
+This means that if the system call number is negative after a
+.B PTRACE_EVENT_SECCOMP
+and the tracee is restarted using
+.BR PTRACE_SYSCALL ,
+the next observed stop will be a syscall-exit-stop,
+rather than the syscall-entry-stop that might have been expected.
+.\"
+.SS PTRACE_EVENT_SECCOMP stops (since Linux 4.8)
+Starting with Linux 4.8,
+.\" commit 93e35efb8de45393cf61ed07f7b407629bf698ea
+the
+.B PTRACE_EVENT_SECCOMP
+stop was reordered to occur between syscall-entry-stop and
+syscall-exit-stop.
+Note that seccomp no longer runs (and no
+.B PTRACE_EVENT_SECCOMP
+will be reported) if the system call is skipped due to
+.BR PTRACE_SYSEMU .
+.P
+Functionally, a
+.B PTRACE_EVENT_SECCOMP
+stop functions comparably
+to a syscall-entry-stop (i.e., continuations using
+.B PTRACE_SYSCALL
+will cause syscall-exit-stops,
+the system call number may be changed and any other modified registers
+are visible to the to-be-executed system call as well).
+Note that there may be,
+but need not have been a preceding syscall-entry-stop.
+.P
+After a
+.B PTRACE_EVENT_SECCOMP
+stop, seccomp will be rerun, with a
+.B SECCOMP_RET_TRACE
+rule now functioning the same as a
+.BR SECCOMP_RET_ALLOW .
+Specifically, this means that if registers are not modified during the
+.B PTRACE_EVENT_SECCOMP
+stop, the system call will then be allowed.
+.\"
+.SS PTRACE_SINGLESTEP stops
+[Details of these kinds of stops are yet to be documented.]
+.\"
+.\" FIXME .
+.\" document stops occurring with PTRACE_SINGLESTEP
+.\"
+.SS Informational and restarting ptrace commands
+Most ptrace commands (all except
+.BR PTRACE_ATTACH ,
+.BR PTRACE_SEIZE ,
+.BR PTRACE_TRACEME ,
+.BR PTRACE_INTERRUPT ,
+and
+.BR PTRACE_KILL )
+require the tracee to be in a ptrace-stop, otherwise they fail with
+.BR ESRCH .
+.P
+When the tracee is in ptrace-stop,
+the tracer can read and write data to
+the tracee using informational commands.
+These commands leave the tracee in ptrace-stopped state:
+.P
+.in +4n
+.EX
+ptrace(PTRACE_PEEKTEXT/PEEKDATA/PEEKUSER, pid, addr, 0);
+ptrace(PTRACE_POKETEXT/POKEDATA/POKEUSER, pid, addr, long_val);
+ptrace(PTRACE_GETREGS/GETFPREGS, pid, 0, &struct);
+ptrace(PTRACE_SETREGS/SETFPREGS, pid, 0, &struct);
+ptrace(PTRACE_GETREGSET, pid, NT_foo, &iov);
+ptrace(PTRACE_SETREGSET, pid, NT_foo, &iov);
+ptrace(PTRACE_GETSIGINFO, pid, 0, &siginfo);
+ptrace(PTRACE_SETSIGINFO, pid, 0, &siginfo);
+ptrace(PTRACE_GETEVENTMSG, pid, 0, &long_var);
+ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_flags);
+.EE
+.in
+.P
+Note that some errors are not reported.
+For example, setting signal information
+.RI ( siginfo )
+may have no effect in some ptrace-stops, yet the call may succeed
+(return 0 and not set
+.IR errno );
+querying
+.B PTRACE_GETEVENTMSG
+may succeed and return some random value if current ptrace-stop
+is not documented as returning a meaningful event message.
+.P
+The call
+.P
+.in +4n
+.EX
+ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_flags);
+.EE
+.in
+.P
+affects one tracee.
+The tracee's current flags are replaced.
+Flags are inherited by new tracees created and "auto-attached" via active
+.BR PTRACE_O_TRACEFORK ,
+.BR PTRACE_O_TRACEVFORK ,
+or
+.B PTRACE_O_TRACECLONE
+options.
+.P
+Another group of commands makes the ptrace-stopped tracee run.
+They have the form:
+.P
+.in +4n
+.EX
+ptrace(cmd, pid, 0, sig);
+.EE
+.in
+.P
+where
+.I cmd
+is
+.BR PTRACE_CONT ,
+.BR PTRACE_LISTEN ,
+.BR PTRACE_DETACH ,
+.BR PTRACE_SYSCALL ,
+.BR PTRACE_SINGLESTEP ,
+.BR PTRACE_SYSEMU ,
+or
+.BR PTRACE_SYSEMU_SINGLESTEP .
+If the tracee is in signal-delivery-stop,
+.I sig
+is the signal to be injected (if it is nonzero).
+Otherwise,
+.I sig
+may be ignored.
+(When restarting a tracee from a ptrace-stop other than signal-delivery-stop,
+recommended practice is to always pass 0 in
+.IR sig .)
+.SS Attaching and detaching
+A thread can be attached to the tracer using the call
+.P
+.in +4n
+.EX
+ptrace(PTRACE_ATTACH, pid, 0, 0);
+.EE
+.in
+.P
+or
+.P
+.in +4n
+.EX
+ptrace(PTRACE_SEIZE, pid, 0, PTRACE_O_flags);
+.EE
+.in
+.P
+.B PTRACE_ATTACH
+sends
+.B SIGSTOP
+to this thread.
+If the tracer wants this
+.B SIGSTOP
+to have no effect, it needs to suppress it.
+Note that if other signals are concurrently sent to
+this thread during attach,
+the tracer may see the tracee enter signal-delivery-stop
+with other signal(s) first!
+The usual practice is to reinject these signals until
+.B SIGSTOP
+is seen, then suppress
+.B SIGSTOP
+injection.
+The design bug here is that a ptrace attach and a concurrently delivered
+.B SIGSTOP
+may race and the concurrent
+.B SIGSTOP
+may be lost.
+.\"
+.\" FIXME Describe how to attach to a thread which is already group-stopped.
+.P
+Since attaching sends
+.B SIGSTOP
+and the tracer usually suppresses it, this may cause a stray
+.B EINTR
+return from the currently executing system call in the tracee,
+as described in the "Signal injection and suppression" section.
+.P
+Since Linux 3.4,
+.B PTRACE_SEIZE
+can be used instead of
+.BR PTRACE_ATTACH .
+.B PTRACE_SEIZE
+does not stop the attached process.
+If you need to stop
+it after attach (or at any other time) without sending it any signals,
+use
+.B PTRACE_INTERRUPT
+command.
+.P
+The operation
+.P
+.in +4n
+.EX
+ptrace(PTRACE_TRACEME, 0, 0, 0);
+.EE
+.in
+.P
+turns the calling thread into a tracee.
+The thread continues to run (doesn't enter ptrace-stop).
+A common practice is to follow the
+.B PTRACE_TRACEME
+with
+.P
+.in +4n
+.EX
+raise(SIGSTOP);
+.EE
+.in
+.P
+and allow the parent (which is our tracer now) to observe our
+signal-delivery-stop.
+.P
+If the
+.BR PTRACE_O_TRACEFORK ,
+.BR PTRACE_O_TRACEVFORK ,
+or
+.B PTRACE_O_TRACECLONE
+options are in effect, then children created by, respectively,
+.BR vfork (2)
+or
+.BR clone (2)
+with the
+.B CLONE_VFORK
+flag,
+.BR fork (2)
+or
+.BR clone (2)
+with the exit signal set to
+.BR SIGCHLD ,
+and other kinds of
+.BR clone (2),
+are automatically attached to the same tracer which traced their parent.
+.B SIGSTOP
+is delivered to the children, causing them to enter
+signal-delivery-stop after they exit the system call which created them.
+.P
+Detaching of the tracee is performed by:
+.P
+.in +4n
+.EX
+ptrace(PTRACE_DETACH, pid, 0, sig);
+.EE
+.in
+.P
+.B PTRACE_DETACH
+is a restarting operation;
+therefore it requires the tracee to be in ptrace-stop.
+If the tracee is in signal-delivery-stop, a signal can be injected.
+Otherwise, the
+.I sig
+parameter may be silently ignored.
+.P
+If the tracee is running when the tracer wants to detach it,
+the usual solution is to send
+.B SIGSTOP
+(using
+.BR tgkill (2),
+to make sure it goes to the correct thread),
+wait for the tracee to stop in signal-delivery-stop for
+.B SIGSTOP
+and then detach it (suppressing
+.B SIGSTOP
+injection).
+A design bug is that this can race with concurrent
+.BR SIGSTOP s.
+Another complication is that the tracee may enter other ptrace-stops
+and needs to be restarted and waited for again, until
+.B SIGSTOP
+is seen.
+Yet another complication is to be sure that
+the tracee is not already ptrace-stopped,
+because no signal delivery happens while it is\[em]not even
+.BR SIGSTOP .
+.\" FIXME Describe how to detach from a group-stopped tracee so that it
+.\" doesn't run, but continues to wait for SIGCONT.
+.P
+If the tracer dies, all tracees are automatically detached and restarted,
+unless they were in group-stop.
+Handling of restart from group-stop is currently buggy,
+but the "as planned" behavior is to leave tracee stopped and waiting for
+.BR SIGCONT .
+If the tracee is restarted from signal-delivery-stop,
+the pending signal is injected.
+.SS execve(2) under ptrace
+.\" clone(2) CLONE_THREAD says:
+.\"     If  any  of the threads in a thread group performs an execve(2),
+.\"     then all threads other than the thread group leader are terminated,
+.\"     and the new program is executed in the thread group leader.
+.\"
+When one thread in a multithreaded process calls
+.BR execve (2),
+the kernel destroys all other threads in the process,
+.\" In Linux 3.1 sources, see fs/exec.c::de_thread()
+and resets the thread ID of the execing thread to the
+thread group ID (process ID).
+(Or, to put things another way, when a multithreaded process does an
+.BR execve (2),
+at completion of the call, it appears as though the
+.BR execve (2)
+occurred in the thread group leader, regardless of which thread did the
+.BR execve (2).)
+This resetting of the thread ID looks very confusing to tracers:
+.IP \[bu] 3
+All other threads stop in
+.B PTRACE_EVENT_EXIT
+stop, if the
+.B PTRACE_O_TRACEEXIT
+option was turned on.
+Then all other threads except the thread group leader report
+death as if they exited via
+.BR _exit (2)
+with exit code 0.
+.IP \[bu]
+The execing tracee changes its thread ID while it is in the
+.BR execve (2).
+(Remember, under ptrace, the "pid" returned from
+.BR waitpid (2),
+or fed into ptrace calls, is the tracee's thread ID.)
+That is, the tracee's thread ID is reset to be the same as its process ID,
+which is the same as the thread group leader's thread ID.
+.IP \[bu]
+Then a
+.B PTRACE_EVENT_EXEC
+stop happens, if the
+.B PTRACE_O_TRACEEXEC
+option was turned on.
+.IP \[bu]
+If the thread group leader has reported its
+.B PTRACE_EVENT_EXIT
+stop by this time,
+it appears to the tracer that
+the dead thread leader "reappears from nowhere".
+(Note: the thread group leader does not report death via
+.I WIFEXITED(status)
+until there is at least one other live thread.
+This eliminates the possibility that the tracer will see
+it dying and then reappearing.)
+If the thread group leader was still alive,
+for the tracer this may look as if thread group leader
+returns from a different system call than it entered,
+or even "returned from a system call even though
+it was not in any system call".
+If the thread group leader was not traced
+(or was traced by a different tracer), then during
+.BR execve (2)
+it will appear as if it has become a tracee of
+the tracer of the execing tracee.
+.P
+All of the above effects are the artifacts of
+the thread ID change in the tracee.
+.P
+The
+.B PTRACE_O_TRACEEXEC
+option is the recommended tool for dealing with this situation.
+First, it enables
+.B PTRACE_EVENT_EXEC
+stop,
+which occurs before
+.BR execve (2)
+returns.
+In this stop, the tracer can use
+.B PTRACE_GETEVENTMSG
+to retrieve the tracee's former thread ID.
+(This feature was introduced in Linux 3.0.)
+Second, the
+.B PTRACE_O_TRACEEXEC
+option disables legacy
+.B SIGTRAP
+generation on
+.BR execve (2).
+.P
+When the tracer receives
+.B PTRACE_EVENT_EXEC
+stop notification,
+it is guaranteed that except this tracee and the thread group leader,
+no other threads from the process are alive.
+.P
+On receiving the
+.B PTRACE_EVENT_EXEC
+stop notification,
+the tracer should clean up all its internal
+data structures describing the threads of this process,
+and retain only one data structure\[em]one which
+describes the single still running tracee, with
+.P
+.in +4n
+.EX
+thread ID == thread group ID == process ID.
+.EE
+.in
+.P
+Example: two threads call
+.BR execve (2)
+at the same time:
+.P
+.nf
+*** we get syscall-enter-stop in thread 1: **
+PID1 execve("/bin/foo", "foo" <unfinished ...>
+*** we issue PTRACE_SYSCALL for thread 1 **
+*** we get syscall-enter-stop in thread 2: **
+PID2 execve("/bin/bar", "bar" <unfinished ...>
+*** we issue PTRACE_SYSCALL for thread 2 **
+*** we get PTRACE_EVENT_EXEC for PID0, we issue PTRACE_SYSCALL **
+*** we get syscall-exit-stop for PID0: **
+PID0 <... execve resumed> )             = 0
+.fi
+.P
+If the
+.B PTRACE_O_TRACEEXEC
+option is
+.I not
+in effect for the execing tracee,
+and if the tracee was
+.BR PTRACE_ATTACH ed
+rather that
+.BR PTRACE_SEIZE d,
+the kernel delivers an extra
+.B SIGTRAP
+to the tracee after
+.BR execve (2)
+returns.
+This is an ordinary signal (similar to one which can be
+generated by
+.IR "kill \-TRAP" ),
+not a special kind of ptrace-stop.
+Employing
+.B PTRACE_GETSIGINFO
+for this signal returns
+.I si_code
+set to 0
+.RI ( SI_USER ).
+This signal may be blocked by signal mask,
+and thus may be delivered (much) later.
+.P
+Usually, the tracer (for example,
+.BR strace (1))
+would not want to show this extra post-execve
+.B SIGTRAP
+signal to the user, and would suppress its delivery to the tracee (if
+.B SIGTRAP
+is set to
+.BR SIG_DFL ,
+it is a killing signal).
+However, determining
+.I which
+.B SIGTRAP
+to suppress is not easy.
+Setting the
+.B PTRACE_O_TRACEEXEC
+option or using
+.B PTRACE_SEIZE
+and thus suppressing this extra
+.B SIGTRAP
+is the recommended approach.
+.SS Real parent
+The ptrace API (ab)uses the standard UNIX parent/child signaling over
+.BR waitpid (2).
+This used to cause the real parent of the process to stop receiving
+several kinds of
+.BR waitpid (2)
+notifications when the child process is traced by some other process.
+.P
+Many of these bugs have been fixed, but as of Linux 2.6.38 several still
+exist; see BUGS below.
+.P
+As of Linux 2.6.38, the following is believed to work correctly:
+.IP \[bu] 3
+exit/death by signal is reported first to the tracer, then,
+when the tracer consumes the
+.BR waitpid (2)
+result, to the real parent (to the real parent only when the
+whole multithreaded process exits).
+If the tracer and the real parent are the same process,
+the report is sent only once.
+.SH RETURN VALUE
+On success, the
+.B PTRACE_PEEK*
+operations return the requested data (but see NOTES),
+the
+.B PTRACE_SECCOMP_GET_FILTER
+operation returns the number of instructions in the BPF program,
+the
+.B PTRACE_GET_SYSCALL_INFO
+operation returns the number of bytes available to be written by the kernel,
+and other operations return zero.
+.P
+On error, all operations return \-1, and
+.I errno
+is set to indicate the error.
+Since the value returned by a successful
+.B PTRACE_PEEK*
+operation may be \-1, the caller must clear
+.I errno
+before the call, and then check it afterward
+to determine whether or not an error occurred.
+.SH ERRORS
+.TP
+.B EBUSY
+(i386 only) There was an error with allocating or freeing a debug register.
+.TP
+.B EFAULT
+There was an attempt to read from or write to an invalid area in
+the tracer's or the tracee's memory,
+probably because the area wasn't mapped or accessible.
+Unfortunately, under Linux, different variations of this fault
+will return
+.B EIO
+or
+.B EFAULT
+more or less arbitrarily.
+.TP
+.B EINVAL
+An attempt was made to set an invalid option.
+.TP
+.B EIO
+.I op
+is invalid, or an attempt was made to read from or
+write to an invalid area in the tracer's or the tracee's memory,
+or there was a word-alignment violation,
+or an invalid signal was specified during a restart operation.
+.TP
+.B EPERM
+The specified process cannot be traced.
+This could be because the
+tracer has insufficient privileges (the required capability is
+.BR CAP_SYS_PTRACE );
+unprivileged processes cannot trace processes that they
+cannot send signals to or those running
+set-user-ID/set-group-ID programs, for obvious reasons.
+Alternatively, the process may already be being traced,
+or (before Linux 2.6.26) be
+.BR init (1)
+(PID 1).
+.TP
+.B ESRCH
+The specified process does not exist, or is not currently being traced
+by the caller, or is not stopped
+(for operations that require a stopped tracee).
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4, 4.3BSD.
+.P
+Before Linux 2.6.26,
+.\" See commit 00cd5c37afd5f431ac186dd131705048c0a11fdb
+.BR init (1),
+the process with PID 1, may not be traced.
+.SH NOTES
+Although arguments to
+.BR ptrace ()
+are interpreted according to the prototype given,
+glibc currently declares
+.BR ptrace ()
+as a variadic function with only the
+.I op
+argument fixed.
+It is recommended to always supply four arguments,
+even if the requested operation does not use them,
+setting unused/ignored arguments to
+.I 0L
+or
+.IR "(void\ *)\ 0".
+.P
+A tracees parent continues to be the tracer even if that tracer calls
+.BR execve (2).
+.P
+The layout of the contents of memory and the USER area are
+quite operating-system- and architecture-specific.
+The offset supplied, and the data returned,
+might not entirely match with the definition of
+.IR "struct user" .
+.\" See http://lkml.org/lkml/2008/5/8/375
+.P
+The size of a "word" is determined by the operating-system variant
+(e.g., for 32-bit Linux it is 32 bits).
+.P
+This page documents the way the
+.BR ptrace ()
+call works currently in Linux.
+Its behavior differs significantly on other flavors of UNIX.
+In any case, use of
+.BR ptrace ()
+is highly specific to the operating system and architecture.
+.\"
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SS Ptrace access mode checking
+Various parts of the kernel-user-space API (not just
+.BR ptrace ()
+operations), require so-called "ptrace access mode" checks,
+whose outcome determines whether an operation is permitted
+(or, in a few cases, causes a "read" operation to return sanitized data).
+These checks are performed in cases where one process can
+inspect sensitive information about,
+or in some cases modify the state of, another process.
+The checks are based on factors such as the credentials and capabilities
+of the two processes,
+whether or not the "target" process is dumpable,
+and the results of checks performed by any enabled Linux Security Module
+(LSM)\[em]for example, SELinux, Yama, or Smack\[em]and by the commoncap LSM
+(which is always invoked).
+.P
+Prior to Linux 2.6.27, all access checks were of a single type.
+Since Linux 2.6.27,
+.\" commit 006ebb40d3d65338bd74abb03b945f8d60e362bd
+two access mode levels are distinguished:
+.TP
+.B PTRACE_MODE_READ
+For "read" operations or other operations that are less dangerous,
+such as:
+.BR get_robust_list (2);
+.BR kcmp (2);
+reading
+.IR /proc/ pid /auxv ,
+.IR /proc/ pid /environ ,
+or
+.IR /proc/ pid /stat ;
+or
+.BR readlink (2)
+of a
+.IR /proc/ pid /ns/*
+file.
+.TP
+.B PTRACE_MODE_ATTACH
+For "write" operations, or other operations that are more dangerous,
+such as: ptrace attaching
+.RB ( PTRACE_ATTACH )
+to another process
+or calling
+.BR process_vm_writev (2).
+.RB ( PTRACE_MODE_ATTACH
+was effectively the default before Linux 2.6.27.)
+.\"
+.\" Regarding the above description of the distinction between
+.\" PTRACE_MODE_READ and PTRACE_MODE_ATTACH, Stephen Smalley notes:
+.\"
+.\"     That was the intent when the distinction was introduced, but it doesn't
+.\"     appear to have been properly maintained, e.g. there is now a common
+.\"     helper lock_trace() that is used for
+.\"     /proc/pid/{stack,syscall,personality} but checks PTRACE_MODE_ATTACH, and
+.\"     PTRACE_MODE_ATTACH is also used in timerslack_ns_write/show().  Likely
+.\"     should review and make them consistent.  There was also some debate
+.\"     about proper handling of /proc/pid/fd.  Arguably that one might belong
+.\"     back in the _ATTACH camp.
+.\"
+.P
+Since Linux 4.5,
+.\" commit caaee6234d05a58c5b4d05e7bf766131b810a657
+the above access mode checks are combined (ORed) with
+one of the following modifiers:
+.TP
+.B PTRACE_MODE_FSCREDS
+Use the caller's filesystem UID and GID (see
+.BR credentials (7))
+or effective capabilities for LSM checks.
+.TP
+.B PTRACE_MODE_REALCREDS
+Use the caller's real UID and GID or permitted capabilities for LSM checks.
+This was effectively the default before Linux 4.5.
+.P
+Because combining one of the credential modifiers with one of
+the aforementioned access modes is typical,
+some macros are defined in the kernel sources for the combinations:
+.TP
+.B PTRACE_MODE_READ_FSCREDS
+Defined as
+.BR "PTRACE_MODE_READ | PTRACE_MODE_FSCREDS" .
+.TP
+.B PTRACE_MODE_READ_REALCREDS
+Defined as
+.BR "PTRACE_MODE_READ | PTRACE_MODE_REALCREDS" .
+.TP
+.B PTRACE_MODE_ATTACH_FSCREDS
+Defined as
+.BR "PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS" .
+.TP
+.B PTRACE_MODE_ATTACH_REALCREDS
+Defined as
+.BR "PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS" .
+.P
+One further modifier can be ORed with the access mode:
+.TP
+.BR PTRACE_MODE_NOAUDIT " (since Linux 3.3)"
+.\" commit 69f594a38967f4540ce7a29b3fd214e68a8330bd
+.\" Just for /proc/pid/stat
+Don't audit this access mode check.
+This modifier is employed for ptrace access mode checks
+(such as checks when reading
+.IR /proc/ pid /stat )
+that merely cause the output to be filtered or sanitized,
+rather than causing an error to be returned to the caller.
+In these cases, accessing the file is not a security violation and
+there is no reason to generate a security audit record.
+This modifier suppresses the generation of
+such an audit record for the particular access check.
+.P
+Note that all of the
+.B PTRACE_MODE_*
+constants described in this subsection are kernel-internal,
+and not visible to user space.
+The constant names are mentioned here in order to label the various kinds of
+ptrace access mode checks that are performed for various system calls
+and accesses to various pseudofiles (e.g., under
+.IR /proc ).
+These names are used in other manual pages to provide a simple
+shorthand for labeling the different kernel checks.
+.P
+The algorithm employed for ptrace access mode checking determines whether
+the calling process is allowed to perform the corresponding action
+on the target process.
+(In the case of opening
+.IR /proc/ pid
+files, the "calling process" is the one opening the file,
+and the process with the corresponding PID is the "target process".)
+The algorithm is as follows:
+.IP (1) 5
+If the calling thread and the target thread are in the same
+thread group, access is always allowed.
+.IP (2)
+If the access mode specifies
+.BR PTRACE_MODE_FSCREDS ,
+then, for the check in the next step,
+employ the caller's filesystem UID and GID.
+(As noted in
+.BR credentials (7),
+the filesystem UID and GID almost always have the same values
+as the corresponding effective IDs.)
+.IP
+Otherwise, the access mode specifies
+.BR PTRACE_MODE_REALCREDS ,
+so use the caller's real UID and GID for the checks in the next step.
+(Most APIs that check the caller's UID and GID use the effective IDs.
+For historical reasons, the
+.B PTRACE_MODE_REALCREDS
+check uses the real IDs instead.)
+.IP (3)
+Deny access if
+.I neither
+of the following is true:
+.RS
+.IP \[bu] 3
+The real, effective, and saved-set user IDs of the target
+match the caller's user ID,
+.I and
+the real, effective, and saved-set group IDs of the target
+match the caller's group ID.
+.IP \[bu]
+The caller has the
+.B CAP_SYS_PTRACE
+capability in the user namespace of the target.
+.RE
+.IP (4)
+Deny access if the target process "dumpable" attribute has a value other than 1
+.RB ( SUID_DUMP_USER ;
+see the discussion of
+.B PR_SET_DUMPABLE
+in
+.BR prctl (2)),
+and the caller does not have the
+.B CAP_SYS_PTRACE
+capability in the user namespace of the target process.
+.IP (5)
+The kernel LSM
+.IR security_ptrace_access_check ()
+interface is invoked to see if ptrace access is permitted.
+The results depend on the LSM(s).
+The implementation of this interface in the commoncap LSM performs
+the following steps:
+.\" (in cap_ptrace_access_check()):
+.RS
+.IP (5.1) 7
+If the access mode includes
+.BR PTRACE_MODE_FSCREDS ,
+then use the caller's
+.I effective
+capability set
+in the following check;
+otherwise (the access mode specifies
+.BR PTRACE_MODE_REALCREDS ,
+so) use the caller's
+.I permitted
+capability set.
+.IP (5.2)
+Deny access if
+.I neither
+of the following is true:
+.RS
+.IP \[bu] 3
+The caller and the target process are in the same user namespace,
+and the caller's capabilities are a superset of the target process's
+.I permitted
+capabilities.
+.IP \[bu]
+The caller has the
+.B CAP_SYS_PTRACE
+capability in the target process's user namespace.
+.RE
+.IP
+Note that the commoncap LSM does not distinguish between
+.B PTRACE_MODE_READ
+and
+.BR PTRACE_MODE_ATTACH .
+.RE
+.IP (6)
+If access has not been denied by any of the preceding steps,
+then access is allowed.
+.\"
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SS /proc/sys/kernel/yama/ptrace_scope
+On systems with the Yama Linux Security Module (LSM) installed
+(i.e., the kernel was configured with
+.BR CONFIG_SECURITY_YAMA ),
+the
+.I /proc/sys/kernel/yama/ptrace_scope
+file (available since Linux 3.4)
+.\" commit 2d514487faf188938a4ee4fb3464eeecfbdcf8eb
+can be used to restrict the ability to trace a process with
+.BR ptrace ()
+(and thus also the ability to use tools such as
+.BR strace (1)
+and
+.BR gdb (1)).
+The goal of such restrictions is to prevent attack escalation whereby
+a compromised process can ptrace-attach to other sensitive processes
+(e.g., a GPG agent or an SSH session) owned by the user in order
+to gain additional credentials that may exist in memory
+and thus expand the scope of the attack.
+.P
+More precisely, the Yama LSM limits two types of operations:
+.IP \[bu] 3
+Any operation that performs a ptrace access mode
+.B PTRACE_MODE_ATTACH
+check\[em]for example,
+.BR ptrace ()
+.BR PTRACE_ATTACH .
+(See the "Ptrace access mode checking" discussion above.)
+.IP \[bu]
+.BR ptrace ()
+.BR PTRACE_TRACEME .
+.P
+A process that has the
+.B CAP_SYS_PTRACE
+capability can update the
+.I /proc/sys/kernel/yama/ptrace_scope
+file with one of the following values:
+.TP
+0 ("classic ptrace permissions")
+No additional restrictions on operations that perform
+.B PTRACE_MODE_ATTACH
+checks (beyond those imposed by the commoncap and other LSMs).
+.IP
+The use of
+.B PTRACE_TRACEME
+is unchanged.
+.TP
+1 ("restricted ptrace") [default value]
+When performing an operation that requires a
+.B PTRACE_MODE_ATTACH
+check, the calling process must either have the
+.B CAP_SYS_PTRACE
+capability in the user namespace of the target process or
+it must have a predefined relationship with the target process.
+By default,
+the predefined relationship is that the target process
+must be a descendant of the caller.
+.IP
+A target process can employ the
+.BR prctl (2)
+.B PR_SET_PTRACER
+operation to declare an additional PID that is allowed to perform
+.B PTRACE_MODE_ATTACH
+operations on the target.
+See the kernel source file
+.I Documentation/admin\-guide/LSM/Yama.rst
+.\" commit 90bb766440f2147486a2acc3e793d7b8348b0c22
+(or
+.I Documentation/security/Yama.txt
+before Linux 4.13)
+for further details.
+.IP
+The use of
+.B PTRACE_TRACEME
+is unchanged.
+.TP
+2 ("admin-only attach")
+Only processes with the
+.B CAP_SYS_PTRACE
+capability in the user namespace of the target process may perform
+.B PTRACE_MODE_ATTACH
+operations or trace children that employ
+.BR PTRACE_TRACEME .
+.TP
+3 ("no attach")
+No process may perform
+.B PTRACE_MODE_ATTACH
+operations or trace children that employ
+.BR PTRACE_TRACEME .
+.IP
+Once this value has been written to the file, it cannot be changed.
+.P
+With respect to values 1 and 2,
+note that creating a new user namespace effectively removes the
+protection offered by Yama.
+This is because a process in the parent user namespace whose effective
+UID matches the UID of the creator of a child namespace
+has all capabilities (including
+.BR CAP_SYS_PTRACE )
+when performing operations within the child user namespace
+(and further-removed descendants of that namespace).
+Consequently, when a process tries to use user namespaces to sandbox itself,
+it inadvertently weakens the protections offered by the Yama LSM.
+.\"
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.\"
+.SS C library/kernel differences
+At the system call level, the
+.BR PTRACE_PEEKTEXT ,
+.BR PTRACE_PEEKDATA ,
+and
+.B PTRACE_PEEKUSER
+operations have a different API: they store the result
+at the address specified by the
+.I data
+parameter, and the return value is the error flag.
+The glibc wrapper function provides the API given in DESCRIPTION above,
+with the result being returned via the function return value.
+.SH BUGS
+On hosts with Linux 2.6 kernel headers,
+.B PTRACE_SETOPTIONS
+is declared with a different value than the one for Linux 2.4.
+This leads to applications compiled with Linux 2.6 kernel
+headers failing when run on Linux 2.4.
+This can be worked around by redefining
+.B PTRACE_SETOPTIONS
+to
+.BR PTRACE_OLDSETOPTIONS ,
+if that is defined.
+.P
+Group-stop notifications are sent to the tracer, but not to real parent.
+Last confirmed on 2.6.38.6.
+.P
+If a thread group leader is traced and exits by calling
+.BR _exit (2),
+.\" Note from Denys Vlasenko:
+.\"     Here "exits" means any kind of death - _exit, exit_group,
+.\"     signal death. Signal death and exit_group cases are trivial,
+.\"     though: since signal death and exit_group kill all other threads
+.\"     too, "until all other threads exit" thing happens rather soon
+.\"     in these cases. Therefore, only _exit presents observably
+.\"     puzzling behavior to ptrace users: thread leader _exit's,
+.\"     but WIFEXITED isn't reported! We are trying to explain here
+.\"     why it is so.
+a
+.B PTRACE_EVENT_EXIT
+stop will happen for it (if requested), but the subsequent
+.B WIFEXITED
+notification will not be delivered until all other threads exit.
+As explained above, if one of other threads calls
+.BR execve (2),
+the death of the thread group leader will
+.I never
+be reported.
+If the execed thread is not traced by this tracer,
+the tracer will never know that
+.BR execve (2)
+happened.
+One possible workaround is to
+.B PTRACE_DETACH
+the thread group leader instead of restarting it in this case.
+Last confirmed on 2.6.38.6.
+.\"  FIXME . need to test/verify this scenario
+.P
+A
+.B SIGKILL
+signal may still cause a
+.B PTRACE_EVENT_EXIT
+stop before actual signal death.
+This may be changed in the future;
+.B SIGKILL
+is meant to always immediately kill tasks even under ptrace.
+Last confirmed on Linux 3.13.
+.P
+Some system calls return with
+.B EINTR
+if a signal was sent to a tracee, but delivery was suppressed by the tracer.
+(This is very typical operation: it is usually
+done by debuggers on every attach, in order to not introduce
+a bogus
+.BR SIGSTOP ).
+As of Linux 3.2.9, the following system calls are affected
+(this list is likely incomplete):
+.BR epoll_wait (2),
+and
+.BR read (2)
+from an
+.BR inotify (7)
+file descriptor.
+The usual symptom of this bug is that when you attach to
+a quiescent process with the command
+.P
+.in +4n
+.EX
+strace \-p <process\-ID>
+.EE
+.in
+.P
+then, instead of the usual
+and expected one-line output such as
+.P
+.in +4n
+.EX
+restart_syscall(<... resuming interrupted call ...>_
+.EE
+.in
+.P
+or
+.P
+.in +4n
+.EX
+select(6, [5], NULL, [5], NULL_
+.EE
+.in
+.P
+('_' denotes the cursor position), you observe more than one line.
+For example:
+.P
+.in +4n
+.EX
+    clock_gettime(CLOCK_MONOTONIC, {15370, 690928118}) = 0
+    epoll_wait(4,_
+.EE
+.in
+.P
+What is not visible here is that the process was blocked in
+.BR epoll_wait (2)
+before
+.BR strace (1)
+has attached to it.
+Attaching caused
+.BR epoll_wait (2)
+to return to user space with the error
+.BR EINTR .
+In this particular case, the program reacted to
+.B EINTR
+by checking the current time, and then executing
+.BR epoll_wait (2)
+again.
+(Programs which do not expect such "stray"
+.B EINTR
+errors may behave in an unintended way upon an
+.BR strace (1)
+attach.)
+.P
+Contrary to the normal rules, the glibc wrapper for
+.BR ptrace ()
+can set
+.I errno
+to zero.
+.SH SEE ALSO
+.BR gdb (1),
+.BR ltrace (1),
+.BR strace (1),
+.BR clone (2),
+.BR execve (2),
+.BR fork (2),
+.BR gettid (2),
+.BR prctl (2),
+.BR seccomp (2),
+.BR sigaction (2),
+.BR tgkill (2),
+.BR vfork (2),
+.BR waitpid (2),
+.BR exec (3),
+.BR capabilities (7),
+.BR signal (7)
diff --git a/man/man2/putmsg.2 b/man/man2/putmsg.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/putmsg.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/putpmsg.2 b/man/man2/putpmsg.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/putpmsg.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/pwrite.2 b/man/man2/pwrite.2
new file mode 100644
index 000000000..87eacb238
--- /dev/null
+++ b/man/man2/pwrite.2
@@ -0,0 +1 @@
+.so man2/pread.2
diff --git a/man/man2/pwrite64.2 b/man/man2/pwrite64.2
new file mode 100644
index 000000000..9290e0a58
--- /dev/null
+++ b/man/man2/pwrite64.2
@@ -0,0 +1 @@
+.so man2/pwrite.2
diff --git a/man/man2/pwritev.2 b/man/man2/pwritev.2
new file mode 100644
index 000000000..54e3384ef
--- /dev/null
+++ b/man/man2/pwritev.2
@@ -0,0 +1 @@
+.so man2/readv.2
diff --git a/man/man2/pwritev2.2 b/man/man2/pwritev2.2
new file mode 100644
index 000000000..54e3384ef
--- /dev/null
+++ b/man/man2/pwritev2.2
@@ -0,0 +1 @@
+.so man2/readv.2
diff --git a/man/man2/query_module.2 b/man/man2/query_module.2
new file mode 100644
index 000000000..60746df56
--- /dev/null
+++ b/man/man2/query_module.2
@@ -0,0 +1,194 @@
+.\" Copyright (C) 1996 Free Software Foundation, Inc.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" 2006-02-09, some reformatting by Luc Van Oostenryck; some
+.\" reformatting and rewordings by mtk
+.\"
+.TH query_module 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+query_module \- query the kernel for various bits pertaining to modules
+.SH SYNOPSIS
+.nf
+.B #include <linux/module.h>
+.P
+.BI "[[deprecated]] int query_module(const char *" name ", int " which ,
+.BI "                                void " buf [. bufsize "], \
+size_t " bufsize ,
+.BI "                                size_t *" ret );
+.fi
+.SH DESCRIPTION
+.IR Note :
+This system call is present only before Linux 2.6.
+.P
+.BR query_module ()
+requests information from the kernel about loadable modules.
+The returned information is placed in the buffer pointed to by
+.IR buf .
+The caller must specify the size of
+.I buf
+in
+.IR bufsize .
+The precise nature and format of the returned information
+depend on the operation specified by
+.IR which .
+Some operations require
+.I name
+to identify a currently loaded module, some allow
+.I name
+to be NULL, indicating the kernel proper.
+.P
+The following values can be specified for
+.IR which :
+.TP
+.B 0
+Returns success, if the kernel supports
+.BR query_module ().
+Used to probe for availability of the system call.
+.TP
+.B QM_MODULES
+Returns the names of all loaded modules.
+The returned buffer consists of a sequence of null-terminated strings;
+.I ret
+is set to the number of
+modules.
+.\" ret is set on ENOSPC
+.TP
+.B QM_DEPS
+Returns the names of all modules used by the indicated module.
+The returned buffer consists of a sequence of null-terminated strings;
+.I ret
+is set to the number of modules.
+.\" ret is set on ENOSPC
+.TP
+.B QM_REFS
+Returns the names of all modules using the indicated module.
+This is the inverse of
+.BR QM_DEPS .
+The returned buffer consists of a sequence of null-terminated strings;
+.I ret
+is set to the number of modules.
+.\" ret is set on ENOSPC
+.TP
+.B QM_SYMBOLS
+Returns the symbols and values exported by the kernel or the indicated
+module.
+The returned buffer is an array of structures of the following form
+.\" ret is set on ENOSPC
+.IP
+.in +4n
+.EX
+struct module_symbol {
+    unsigned long value;
+    unsigned long name;
+};
+.EE
+.in
+.IP
+followed by null-terminated strings.
+The value of
+.I name
+is the character offset of the string relative to the start of
+.IR buf ;
+.I ret
+is set to the number of symbols.
+.TP
+.B QM_INFO
+Returns miscellaneous information about the indicated module.
+The output buffer format is:
+.IP
+.in +4n
+.EX
+struct module_info {
+    unsigned long address;
+    unsigned long size;
+    unsigned long flags;
+};
+.EE
+.in
+.IP
+where
+.I address
+is the kernel address at which the module resides,
+.I size
+is the size of the module in bytes, and
+.I flags
+is a mask of
+.BR MOD_RUNNING ,
+.BR MOD_AUTOCLEAN ,
+and so on, that indicates the current status of the module
+(see the Linux kernel source file
+.IR include/linux/module.h ).
+.I ret
+is set to the size of the
+.I module_info
+structure.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+At least one of
+.IR name ,
+.IR buf ,
+or
+.I ret
+was outside the program's accessible address space.
+.TP
+.B EINVAL
+Invalid
+.IR which ;
+or
+.I name
+is NULL (indicating "the kernel"),
+but this is not permitted with the specified value of
+.IR which .
+.\" Not permitted with QM_DEPS, QM_REFS, or QM_INFO.
+.TP
+.B ENOENT
+No module by that
+.I name
+exists.
+.TP
+.B ENOSPC
+The buffer size provided was too small.
+.I ret
+is set to the minimum size needed.
+.TP
+.B ENOSYS
+.BR query_module ()
+is not supported in this version of the kernel
+(e.g., Linux 2.6 or later).
+.SH STANDARDS
+Linux.
+.SH VERSIONS
+Removed in Linux 2.6.
+.\" Removed in Linux 2.5.48
+.P
+Some of the information that was formerly available via
+.BR query_module ()
+can be obtained from
+.IR /proc/modules ,
+.IR /proc/kallsyms ,
+and the files under the directory
+.IR /sys/module .
+.P
+The
+.BR query_module ()
+system call is not supported by glibc.
+No declaration is provided in glibc headers, but,
+through a quirk of history, glibc does export an ABI for this system call.
+Therefore, in order to employ this system call,
+it is sufficient to manually declare the interface in your code;
+alternatively, you can invoke the system call using
+.BR syscall (2).
+.SH SEE ALSO
+.BR create_module (2),
+.BR delete_module (2),
+.BR get_kernel_syms (2),
+.BR init_module (2),
+.BR lsmod (8),
+.BR modinfo (8)
diff --git a/man/man2/quotactl.2 b/man/man2/quotactl.2
new file mode 100644
index 000000000..3807507e8
--- /dev/null
+++ b/man/man2/quotactl.2
@@ -0,0 +1,806 @@
+.\" Copyright (c) 2010, Jan Kara
+.\" A few pieces copyright (c) 1996 Andries Brouwer (aeb@cwi.nl)
+.\" and copyright 2010 (c) Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH quotactl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+quotactl \- manipulate disk quotas
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/quota.h>
+.BR "#include <xfs/xqm.h>" " /* Definition of " Q_X* " and " XFS_QUOTA_* \
+" constants"
+.RB    "                        (or " <linux/dqblk_xfs.h> "; see NOTES) */"
+.P
+.BI "int quotactl(int " op ", const char *_Nullable " special ", int " id ,
+.BI "             caddr_t " addr );
+.fi
+.SH DESCRIPTION
+The quota system can be used to set per-user, per-group, and per-project limits
+on the amount of disk space used on a filesystem.
+For each user and/or group,
+a soft limit and a hard limit can be set for each filesystem.
+The hard limit can't be exceeded.
+The soft limit can be exceeded, but warnings will ensue.
+Moreover, the user can't exceed the soft limit for more than grace period
+duration (one week by default) at a time;
+after this, the soft limit counts as a hard limit.
+.P
+The
+.BR quotactl ()
+call manipulates disk quotas.
+The
+.I op
+argument indicates an operation to be applied to the user or
+group ID specified in
+.IR id .
+To initialize the
+.I op
+argument, use the
+.I QCMD(subop, type)
+macro.
+The
+.I type
+value is either
+.BR USRQUOTA ,
+for user quotas,
+.BR GRPQUOTA ,
+for group quotas, or (since Linux 4.1)
+.\" 847aac644e92e5624f2c153bab409bf713d5ff9a
+.BR PRJQUOTA ,
+for project quotas.
+The
+.I subop
+value is described below.
+.P
+The
+.I special
+argument is a pointer to a null-terminated string containing the pathname
+of the (mounted) block special device for the filesystem being manipulated.
+.P
+The
+.I addr
+argument is the address of an optional, operation-specific, data structure
+that is copied in or out of the system.
+The interpretation of
+.I addr
+is given with each operation below.
+.P
+The
+.I subop
+value is one of the following operations:
+.TP
+.B Q_QUOTAON
+Turn on quotas for a filesystem.
+The
+.I id
+argument is the identification number of the quota format to be used.
+Currently, there are three supported quota formats:
+.RS
+.TP 13
+.B QFMT_VFS_OLD
+The original quota format.
+.TP
+.B QFMT_VFS_V0
+The standard VFS v0 quota format, which can handle 32-bit UIDs and GIDs
+and quota limits up to 2\[ha]42 bytes and 2\[ha]32 inodes.
+.TP
+.B QFMT_VFS_V1
+A quota format that can handle 32-bit UIDs and GIDs
+and quota limits of 2\[ha]63 \- 1 bytes and 2\[ha]63 \- 1 inodes.
+.RE
+.IP
+The
+.I addr
+argument points to the pathname of a file containing the quotas for
+the filesystem.
+The quota file must exist; it is normally created with the
+.BR quotacheck (8)
+program
+.IP
+Quota information can be also stored in hidden system inodes
+for ext4, XFS, and other filesystems if the filesystem is configured so.
+In this case, there are no visible quota files and there is no need to
+use
+.BR quotacheck (8).
+Quota information is always kept consistent by the filesystem and the
+.B Q_QUOTAON
+operation serves only to enable enforcement of quota limits.
+The presence of hidden
+system inodes with quota information is indicated by the
+.B DQF_SYS_FILE
+flag in the
+.I dqi_flags
+field returned by the
+.B Q_GETINFO
+operation.
+.IP
+This operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+.TP
+.B Q_QUOTAOFF
+Turn off quotas for a filesystem.
+The
+.I addr
+and
+.I id
+arguments are ignored.
+This operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+.TP
+.B Q_GETQUOTA
+Get disk quota limits and current usage for user or group
+.IR id .
+The
+.I addr
+argument is a pointer to a
+.I dqblk
+structure defined in
+.I <sys/quota.h>
+as follows:
+.IP
+.in +4n
+.EX
+/* uint64_t is an unsigned 64\-bit integer;
+   uint32_t is an unsigned 32\-bit integer */
+\&
+struct dqblk {      /* Definition since Linux 2.4.22 */
+    uint64_t dqb_bhardlimit;  /* Absolute limit on disk
+                                 quota blocks alloc */
+    uint64_t dqb_bsoftlimit;  /* Preferred limit on
+                                 disk quota blocks */
+    uint64_t dqb_curspace;    /* Current occupied space
+                                 (in bytes) */
+    uint64_t dqb_ihardlimit;  /* Maximum number of
+                                 allocated inodes */
+    uint64_t dqb_isoftlimit;  /* Preferred inode limit */
+    uint64_t dqb_curinodes;   /* Current number of
+                                 allocated inodes */
+    uint64_t dqb_btime;       /* Time limit for excessive
+                                 disk use */
+    uint64_t dqb_itime;       /* Time limit for excessive
+                                 files */
+    uint32_t dqb_valid;       /* Bit mask of QIF_*
+                                 constants */
+};
+\&
+/* Flags in dqb_valid that indicate which fields in
+   dqblk structure are valid. */
+\&
+#define QIF_BLIMITS   1
+#define QIF_SPACE     2
+#define QIF_ILIMITS   4
+#define QIF_INODES    8
+#define QIF_BTIME     16
+#define QIF_ITIME     32
+#define QIF_LIMITS    (QIF_BLIMITS | QIF_ILIMITS)
+#define QIF_USAGE     (QIF_SPACE | QIF_INODES)
+#define QIF_TIMES     (QIF_BTIME | QIF_ITIME)
+#define QIF_ALL       (QIF_LIMITS | QIF_USAGE | QIF_TIMES)
+.EE
+.in
+.IP
+The
+.I dqb_valid
+field is a bit mask that is set to indicate the entries in the
+.I dqblk
+structure that are valid.
+Currently, the kernel fills in all entries of the
+.I dqblk
+structure and marks them as valid in the
+.I dqb_valid
+field.
+Unprivileged users may retrieve only their own quotas;
+a privileged user
+.RB ( CAP_SYS_ADMIN )
+can retrieve the quotas of any user.
+.TP
+.BR Q_GETNEXTQUOTA " (since Linux 4.6)"
+.\" commit 926132c0257a5a8d149a6a395cc3405e55420566
+This operation is the same as
+.BR Q_GETQUOTA ,
+but it returns quota information for the next ID greater than or equal to
+.I id
+that has a quota set.
+.IP
+The
+.I addr
+argument is a pointer to a
+.I nextdqblk
+structure whose fields are as for the
+.IR dqblk ,
+except for the addition of a
+.I dqb_id
+field that is used to return the ID for which
+quota information is being returned:
+.IP
+.in +4n
+.EX
+struct nextdqblk {
+    uint64_t dqb_bhardlimit;
+    uint64_t dqb_bsoftlimit;
+    uint64_t dqb_curspace;
+    uint64_t dqb_ihardlimit;
+    uint64_t dqb_isoftlimit;
+    uint64_t dqb_curinodes;
+    uint64_t dqb_btime;
+    uint64_t dqb_itime;
+    uint32_t dqb_valid;
+    uint32_t dqb_id;
+};
+.EE
+.in
+.TP
+.B Q_SETQUOTA
+Set quota information for user or group
+.IR id ,
+using the information supplied in the
+.I dqblk
+structure pointed to by
+.IR addr .
+The
+.I dqb_valid
+field of the
+.I dqblk
+structure indicates which entries in the structure have been set by the caller.
+This operation supersedes the
+.B Q_SETQLIM
+and
+.B Q_SETUSE
+operations in the previous quota interfaces.
+This operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+.TP
+.BR Q_GETINFO " (since Linux 2.4.22)"
+Get information (like grace times) about quotafile.
+The
+.I addr
+argument should be a pointer to a
+.I dqinfo
+structure.
+This structure is defined in
+.I <sys/quota.h>
+as follows:
+.IP
+.in +4n
+.EX
+/* uint64_t is an unsigned 64\-bit integer;
+   uint32_t is an unsigned 32\-bit integer */
+\&
+struct dqinfo {         /* Defined since Linux 2.4.22 */
+    uint64_t dqi_bgrace;  /* Time before block soft limit
+                             becomes hard limit */
+    uint64_t dqi_igrace;  /* Time before inode soft limit
+                             becomes hard limit */
+    uint32_t dqi_flags;   /* Flags for quotafile
+                             (DQF_*) */
+    uint32_t dqi_valid;
+};
+\&
+/* Bits for dqi_flags */
+\&
+/* Quota format QFMT_VFS_OLD */
+\&
+#define DQF_ROOT_SQUASH (1 << 0) /* Root squash enabled */
+              /* Before Linux v4.0, this had been defined
+                 privately as V1_DQF_RSQUASH */
+\&
+/* Quota format QFMT_VFS_V0 / QFMT_VFS_V1 */
+\&
+#define DQF_SYS_FILE    (1 << 16)   /* Quota stored in
+                                       a system file */
+\&
+/* Flags in dqi_valid that indicate which fields in
+   dqinfo structure are valid. */
+\&
+#define IIF_BGRACE  1
+#define IIF_IGRACE  2
+#define IIF_FLAGS   4
+#define IIF_ALL     (IIF_BGRACE | IIF_IGRACE | IIF_FLAGS)
+.EE
+.in
+.IP
+The
+.I dqi_valid
+field in the
+.I dqinfo
+structure indicates the entries in the structure that are valid.
+Currently, the kernel fills in all entries of the
+.I dqinfo
+structure and marks them all as valid in the
+.I dqi_valid
+field.
+The
+.I id
+argument is ignored.
+.TP
+.BR Q_SETINFO " (since Linux 2.4.22)"
+Set information about quotafile.
+The
+.I addr
+argument should be a pointer to a
+.I dqinfo
+structure.
+The
+.I dqi_valid
+field of the
+.I dqinfo
+structure indicates the entries in the structure
+that have been set by the caller.
+This operation supersedes the
+.B Q_SETGRACE
+and
+.B Q_SETFLAGS
+operations in the previous quota interfaces.
+The
+.I id
+argument is ignored.
+This operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+.TP
+.BR Q_GETFMT " (since Linux 2.4.22)"
+Get quota format used on the specified filesystem.
+The
+.I addr
+argument should be a pointer to a 4-byte buffer
+where the format number will be stored.
+.TP
+.B Q_SYNC
+Update the on-disk copy of quota usages for a filesystem.
+If
+.I special
+is NULL, then all filesystems with active quotas are sync'ed.
+The
+.I addr
+and
+.I id
+arguments are ignored.
+.TP
+.BR Q_GETSTATS " (supported up to Linux 2.4.21)"
+Get statistics and other generic information about the quota subsystem.
+The
+.I addr
+argument should be a pointer to a
+.I dqstats
+structure in which data should be stored.
+This structure is defined in
+.IR <sys/quota.h> .
+The
+.I special
+and
+.I id
+arguments are ignored.
+.IP
+This operation is obsolete and was removed in Linux 2.4.22.
+Files in
+.I /proc/sys/fs/quota/
+carry the information instead.
+.P
+For XFS filesystems making use of the XFS Quota Manager (XQM),
+the above operations are bypassed and the following operations are used:
+.TP
+.B Q_XQUOTAON
+Turn on quotas for an XFS filesystem.
+XFS provides the ability to turn on/off quota limit enforcement
+with quota accounting.
+Therefore, XFS expects
+.I addr
+to be a pointer to an
+.I "unsigned int"
+that contains a bitwise combination of the following flags (defined in
+.IR <xfs/xqm.h> ):
+.IP
+.in +4n
+.EX
+XFS_QUOTA_UDQ_ACCT  /* User quota accounting */
+XFS_QUOTA_UDQ_ENFD  /* User quota limits enforcement */
+XFS_QUOTA_GDQ_ACCT  /* Group quota accounting */
+XFS_QUOTA_GDQ_ENFD  /* Group quota limits enforcement */
+XFS_QUOTA_PDQ_ACCT  /* Project quota accounting */
+XFS_QUOTA_PDQ_ENFD  /* Project quota limits enforcement */
+.EE
+.in
+.IP
+This operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+The
+.I id
+argument is ignored.
+.TP
+.B Q_XQUOTAOFF
+Turn off quotas for an XFS filesystem.
+As with
+.BR Q_QUOTAON ,
+XFS filesystems expect a pointer to an
+.I "unsigned int"
+that specifies whether quota accounting and/or limit enforcement need
+to be turned off (using the same flags as for
+.B Q_XQUOTAON
+operation).
+This operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+The
+.I id
+argument is ignored.
+.TP
+.B Q_XGETQUOTA
+Get disk quota limits and current usage for user
+.IR id .
+The
+.I addr
+argument is a pointer to an
+.I fs_disk_quota
+structure, which is defined in
+.I <xfs/xqm.h>
+as follows:
+.IP
+.in +4n
+.EX
+/* All the blk units are in BBs (Basic Blocks) of
+   512 bytes. */
+\&
+#define FS_DQUOT_VERSION  1  /* fs_disk_quota.d_version */
+\&
+#define XFS_USER_QUOTA    (1<<0)  /* User quota type */
+#define XFS_PROJ_QUOTA    (1<<1)  /* Project quota type */
+#define XFS_GROUP_QUOTA   (1<<2)  /* Group quota type */
+\&
+struct fs_disk_quota {
+    int8_t   d_version;   /* Version of this structure */
+    int8_t   d_flags;     /* XFS_{USER,PROJ,GROUP}_QUOTA */
+    uint16_t d_fieldmask; /* Field specifier */
+    uint32_t d_id;        /* User, project, or group ID */
+    uint64_t d_blk_hardlimit; /* Absolute limit on
+                                 disk blocks */
+    uint64_t d_blk_softlimit; /* Preferred limit on
+                                 disk blocks */
+    uint64_t d_ino_hardlimit; /* Maximum # allocated
+                                 inodes */
+    uint64_t d_ino_softlimit; /* Preferred inode limit */
+    uint64_t d_bcount;    /* # disk blocks owned by
+                             the user */
+    uint64_t d_icount;    /* # inodes owned by the user */
+    int32_t  d_itimer;    /* Zero if within inode limits */
+                          /* If not, we refuse service */
+    int32_t  d_btimer;    /* Similar to above; for
+                             disk blocks */
+    uint16_t d_iwarns;    /* # warnings issued with
+                             respect to # of inodes */
+    uint16_t d_bwarns;    /* # warnings issued with
+                             respect to disk blocks */
+    int32_t  d_padding2;  /* Padding \- for future use */
+    uint64_t d_rtb_hardlimit; /* Absolute limit on realtime
+                                 (RT) disk blocks */
+    uint64_t d_rtb_softlimit; /* Preferred limit on RT
+                                 disk blocks */
+    uint64_t d_rtbcount;  /* # realtime blocks owned */
+    int32_t  d_rtbtimer;  /* Similar to above; for RT
+                             disk blocks */
+    uint16_t d_rtbwarns;  /* # warnings issued with
+                             respect to RT disk blocks */
+    int16_t  d_padding3;  /* Padding \- for future use */
+    char     d_padding4[8];   /* Yet more padding */
+};
+.EE
+.in
+.IP
+Unprivileged users may retrieve only their own quotas;
+a privileged user
+.RB ( CAP_SYS_ADMIN )
+may retrieve the quotas of any user.
+.TP
+.BR Q_XGETNEXTQUOTA " (since Linux 4.6)"
+.\" commit 8b37524962b9c54423374717786198f5c0820a28
+This operation is the same as
+.BR Q_XGETQUOTA ,
+but it returns (in the
+.I fs_disk_quota
+structure pointed by
+.IR addr )
+quota information for the next ID greater than or equal to
+.I id
+that has a quota set.
+Note that since
+.I fs_disk_quota
+already has
+.I q_id
+field, no separate structure type is needed (in contrast with
+.B Q_GETQUOTA
+and
+.B Q_GETNEXTQUOTA
+operations)
+.TP
+.B Q_XSETQLIM
+Set disk quota limits for user
+.IR id .
+The
+.I addr
+argument is a pointer to an
+.I fs_disk_quota
+structure.
+This operation requires privilege
+.RB ( CAP_SYS_ADMIN ).
+.TP
+.B Q_XGETQSTAT
+Returns XFS filesystem-specific quota information in the
+.I fs_quota_stat
+structure pointed by
+.IR addr .
+This is useful for finding out how much space is used to store quota
+information, and also to get the quota on/off status of a given local XFS
+filesystem.
+The
+.I fs_quota_stat
+structure itself is defined as follows:
+.IP
+.in +4n
+.EX
+#define FS_QSTAT_VERSION 1  /* fs_quota_stat.qs_version */
+\&
+struct fs_qfilestat {
+    uint64_t qfs_ino;       /* Inode number */
+    uint64_t qfs_nblks;     /* Number of BBs
+                               512\-byte\-blocks */
+    uint32_t qfs_nextents;  /* Number of extents */
+};
+\&
+struct fs_quota_stat {
+    int8_t   qs_version; /* Version number for
+                            future changes */
+    uint16_t qs_flags; /* XFS_QUOTA_{U,P,G}DQ_{ACCT,ENFD} */
+    int8_t   qs_pad;   /* Unused */
+    struct fs_qfilestat qs_uquota;  /* User quota storage
+                                       information */
+    struct fs_qfilestat qs_gquota;  /* Group quota storage
+                                       information */
+    uint32_t qs_incoredqs;   /* Number of dquots in core */
+    int32_t  qs_btimelimit;  /* Limit for blocks timer */
+    int32_t  qs_itimelimit;  /* Limit for inodes timer */
+    int32_t  qs_rtbtimelimit;/* Limit for RT
+                                blocks timer */
+    uint16_t qs_bwarnlimit;  /* Limit for # of warnings */
+    uint16_t qs_iwarnlimit;  /* Limit for # of warnings */
+};
+.EE
+.in
+.IP
+The
+.I id
+argument is ignored.
+.TP
+.B Q_XGETQSTATV
+Returns XFS filesystem-specific quota information in the
+.I fs_quota_statv
+pointed to by
+.IR addr .
+This version of the operation uses a structure with proper versioning support,
+along with appropriate layout (all fields are naturally aligned) and
+padding to avoiding special compat handling;
+it also provides the ability to get statistics regarding
+the project quota file.
+The
+.I fs_quota_statv
+structure itself is defined as follows:
+.IP
+.in +4n
+.EX
+#define FS_QSTATV_VERSION1 1 /* fs_quota_statv.qs_version */
+\&
+struct fs_qfilestatv {
+    uint64_t qfs_ino;       /* Inode number */
+    uint64_t qfs_nblks;     /* Number of BBs
+                               512\-byte\-blocks */
+    uint32_t qfs_nextents;  /* Number of extents */
+    uint32_t qfs_pad;       /* Pad for 8\-byte alignment */
+};
+\&
+struct fs_quota_statv {
+    int8_t   qs_version;    /* Version for future
+                               changes */
+    uint8_t  qs_pad1;       /* Pad for 16\-bit alignment */
+    uint16_t qs_flags;      /* XFS_QUOTA_.* flags */
+    uint32_t qs_incoredqs;  /* Number of dquots incore */
+    struct fs_qfilestatv qs_uquota;  /* User quota
+                                        information */
+    struct fs_qfilestatv qs_gquota;  /* Group quota
+                                        information */
+    struct fs_qfilestatv qs_pquota;  /* Project quota
+                                        information */
+    int32_t  qs_btimelimit;   /* Limit for blocks timer */
+    int32_t  qs_itimelimit;   /* Limit for inodes timer */
+    int32_t  qs_rtbtimelimit; /* Limit for RT blocks
+                                 timer */
+    uint16_t qs_bwarnlimit;   /* Limit for # of warnings */
+    uint16_t qs_iwarnlimit;   /* Limit for # of warnings */
+    uint64_t qs_pad2[8];      /* For future proofing */
+};
+.EE
+.in
+.IP
+The
+.I qs_version
+field of the structure should be filled with the version of the structure
+supported by the callee (for now, only
+.I FS_QSTAT_VERSION1
+is supported).
+The kernel will fill the structure in accordance with
+version provided.
+The
+.I id
+argument is ignored.
+.TP
+.BR Q_XQUOTARM " (buggy until Linux 3.16)"
+.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
+Free the disk space taken by disk quotas.
+The
+.I addr
+argument should be a pointer to an
+.I "unsigned int"
+value containing flags (the same as in
+.I d_flags
+field of
+.I fs_disk_quota
+structure)
+which identify what types of quota
+should be removed.
+(Note that the quota type passed in the
+.I op
+argument is ignored, but should remain valid in order to pass preliminary
+quotactl syscall handler checks.)
+.IP
+Quotas must have already been turned off.
+The
+.I id
+argument is ignored.
+.TP
+.BR Q_XQUOTASYNC " (since Linux 2.6.15; no-op since Linux 3.4)"
+.\" Added in commit ee34807a65aa0c5911dc27682863afca780a003e
+This operation was an XFS quota equivalent to
+.BR Q_SYNC ,
+but it is no-op since Linux 3.4,
+.\" 4b217ed9e30f94b6e8e5e262020ef0ceab6113af
+as
+.BR sync (1)
+writes quota information to disk now
+(in addition to the other filesystem metadata that it writes out).
+The
+.IR special ", " id " and " addr
+arguments are ignored.
+.SH RETURN VALUE
+On success,
+.BR quotactl ()
+returns 0; on error \-1
+is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.I op
+is
+.BR Q_QUOTAON ,
+and the quota file pointed to by
+.I addr
+exists, but is not a regular file or
+is not on the filesystem pointed to by
+.IR special .
+.TP
+.B EBUSY
+.I op
+is
+.BR Q_QUOTAON ,
+but another
+.B Q_QUOTAON
+had already been performed.
+.TP
+.B EFAULT
+.I addr
+or
+.I special
+is invalid.
+.TP
+.B EINVAL
+.I op
+or
+.I type
+is invalid.
+.TP
+.B EINVAL
+.I op
+is
+.BR Q_QUOTAON ,
+but the specified quota file is corrupted.
+.TP
+.BR EINVAL " (since Linux 5.5)"
+.\" 3dd4d40b420846dd35869ccc8f8627feef2cff32
+.I op
+is
+.BR Q_XQUOTARM ,
+but
+.I addr
+does not point to valid quota types.
+.TP
+.B ENOENT
+The file specified by
+.I special
+or
+.I addr
+does not exist.
+.TP
+.B ENOSYS
+The kernel has not been compiled with the
+.B CONFIG_QUOTA
+option.
+.TP
+.B ENOTBLK
+.I special
+is not a block device.
+.TP
+.B EPERM
+The caller lacked the required privilege
+.RB ( CAP_SYS_ADMIN )
+for the specified operation.
+.TP
+.B ERANGE
+.I op
+is
+.BR Q_SETQUOTA ,
+but the specified limits are out of the range allowed by the quota format.
+.TP
+.B ESRCH
+No disk quota is found for the indicated user.
+Quotas have not been turned on for this filesystem.
+.TP
+.B ESRCH
+.I op
+is
+.BR Q_QUOTAON ,
+but the specified quota format was not found.
+.TP
+.B ESRCH
+.I op
+is
+.B Q_GETNEXTQUOTA
+or
+.BR Q_XGETNEXTQUOTA ,
+but there is no ID greater than or equal to
+.I id
+that has an active quota.
+.SH NOTES
+Instead of
+.I <xfs/xqm.h>
+one can use
+.IR <linux/dqblk_xfs.h> ,
+taking into account that there are several naming discrepancies:
+.IP \[bu] 3
+Quota enabling flags (of format
+.BR XFS_QUOTA_[UGP]DQ_{ACCT,ENFD} )
+are defined without a leading "X", as
+.BR FS_QUOTA_[UGP]DQ_{ACCT,ENFD} .
+.IP \[bu]
+The same is true for
+.B XFS_{USER,GROUP,PROJ}_QUOTA
+quota type flags, which are defined as
+.BR FS_{USER,GROUP,PROJ}_QUOTA .
+.IP \[bu]
+The
+.I dqblk_xfs.h
+header file defines its own
+.BR XQM_USRQUOTA ,
+.BR XQM_GRPQUOTA ,
+and
+.B XQM_PRJQUOTA
+constants for the available quota types, but their values are the same as for
+constants without the
+.B XQM_
+prefix.
+.SH SEE ALSO
+.BR quota (1),
+.BR getrlimit (2),
+.BR quotacheck (8),
+.BR quotaon (8)
diff --git a/man/man2/read.2 b/man/man2/read.2
new file mode 100644
index 000000000..c74f62a0b
--- /dev/null
+++ b/man/man2/read.2
@@ -0,0 +1,245 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"  and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\"  and Copyright (C) 2009-2015 Michael Kerrisk, <mtk.manpages.gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 00:06:00 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Wed Jan 17 16:02:32 1996 by Michael Haardt
+.\"   <michael@cantor.informatik.rwth-aachen.de>
+.\" Modified Thu Apr 11 19:26:35 1996 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Sun Jul 21 18:59:33 1996 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Fri Jan 31 16:47:33 1997 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Sat Jul 12 20:45:39 1997 by Michael Haardt
+.\"   <michael@cantor.informatik.rwth-aachen.de>
+.\"
+.TH read 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+read \- read from a file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "ssize_t read(int " fd ", void " buf [. count "], size_t " count );
+.fi
+.SH DESCRIPTION
+.BR read ()
+attempts to read up to
+.I count
+bytes from file descriptor
+.I fd
+into the buffer starting at
+.IR buf .
+.P
+On files that support seeking,
+the read operation commences at the file offset,
+and the file offset is incremented by the number of bytes read.
+If the file offset is at or past the end of file,
+no bytes are read, and
+.BR read ()
+returns zero.
+.P
+If
+.I count
+is zero,
+.BR read ()
+.I may
+detect the errors described below.
+In the absence of any errors,
+or if
+.BR read ()
+does not check for errors, a
+.BR read ()
+with a
+.I count
+of 0 returns zero and has no other effects.
+.P
+According to POSIX.1, if
+.I count
+is greater than
+.BR SSIZE_MAX ,
+the result is implementation-defined;
+see NOTES for the upper limit on Linux.
+.SH RETURN VALUE
+On success, the number of bytes read is returned (zero indicates end of
+file), and the file position is advanced by this number.
+It is not an error if this number is smaller than the number of bytes
+requested; this may happen for example because fewer bytes are actually
+available right now (maybe because we were close to end-of-file, or
+because we are reading from a pipe, or from a terminal), or because
+.BR read ()
+was interrupted by a signal.
+See also NOTES.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+In this case, it is left unspecified whether
+the file position (if any) changes.
+.SH ERRORS
+.TP
+.B EAGAIN
+The file descriptor
+.I fd
+refers to a file other than a socket and has been marked nonblocking
+.RB ( O_NONBLOCK ),
+and the read would block.
+See
+.BR open (2)
+for further details on the
+.B O_NONBLOCK
+flag.
+.TP
+.BR EAGAIN " or " EWOULDBLOCK
+.\" Actually EAGAIN on Linux
+The file descriptor
+.I fd
+refers to a socket and has been marked nonblocking
+.RB ( O_NONBLOCK ),
+and the read would block.
+POSIX.1-2001 allows either error to be returned for this case,
+and does not require these constants to have the same value,
+so a portable application should check for both possibilities.
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor or is not open for reading.
+.TP
+.B EFAULT
+.I buf
+is outside your accessible address space.
+.TP
+.B EINTR
+The call was interrupted by a signal before any data was read; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I fd
+is attached to an object which is unsuitable for reading;
+or the file was opened with the
+.B O_DIRECT
+flag, and either the address specified in
+.IR buf ,
+the value specified in
+.IR count ,
+or the file offset is not suitably aligned.
+.TP
+.B EINVAL
+.I fd
+was created via a call to
+.BR timerfd_create (2)
+and the wrong size buffer was given to
+.BR read ();
+see
+.BR timerfd_create (2)
+for further information.
+.TP
+.B EIO
+I/O error.
+This will happen for example when the process is in a
+background process group, tries to read from its controlling terminal,
+and either it is ignoring or blocking
+.B SIGTTIN
+or its process group
+is orphaned.
+It may also occur when there is a low-level I/O error
+while reading from a disk or tape.
+A further possible cause of
+.B EIO
+on networked filesystems is when an advisory lock had been taken
+out on the file descriptor and this lock has been lost.
+See the
+.I "Lost locks"
+section of
+.BR fcntl (2)
+for further details.
+.TP
+.B EISDIR
+.I fd
+refers to a directory.
+.P
+Other errors may occur, depending on the object connected to
+.IR fd .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+SVr4, 4.3BSD, POSIX.1-2001.
+.SH NOTES
+On Linux,
+.BR read ()
+(and similar system calls) will transfer at most
+0x7ffff000 (2,147,479,552) bytes,
+returning the number of bytes actually transferred.
+.\" commit e28cc71572da38a5a12c1cfe4d7032017adccf69
+(This is true on both 32-bit and 64-bit systems.)
+.P
+On NFS filesystems, reading small amounts of data will update the
+timestamp only the first time, subsequent calls may not do so.
+This is caused
+by client side attribute caching, because most if not all NFS clients
+leave
+.I st_atime
+(last file access time)
+updates to the server, and client side reads satisfied from the
+client's cache will not cause
+.I st_atime
+updates on the server as there are no
+server-side reads.
+UNIX semantics can be obtained by disabling client-side attribute caching,
+but in most situations this will substantially
+increase server load and decrease performance.
+.SH BUGS
+According to POSIX.1-2008/SUSv4 Section XSI 2.9.7
+("Thread Interactions with Regular File Operations"):
+.P
+.RS 4
+All of the following functions shall be atomic with respect to
+each other in the effects specified in POSIX.1-2008 when they
+operate on regular files or symbolic links: ...
+.RE
+.P
+Among the APIs subsequently listed are
+.BR read ()
+and
+.BR readv (2).
+And among the effects that should be atomic across threads (and processes)
+are updates of the file offset.
+However, before Linux 3.14,
+this was not the case: if two processes that share
+an open file description (see
+.BR open (2))
+perform a
+.BR read ()
+(or
+.BR readv (2))
+at the same time, then the I/O operations were not atomic
+with respect to updating the file offset,
+with the result that the reads in the two processes
+might (incorrectly) overlap in the blocks of data that they obtained.
+This problem was fixed in Linux 3.14.
+.\" http://thread.gmane.org/gmane.linux.kernel/1649458
+.\"    From: Michael Kerrisk (man-pages <mtk.manpages <at> gmail.com>
+.\"    Subject: Update of file offset on write() etc. is non-atomic with I/O
+.\"    Date: 2014-02-17 15:41:37 GMT
+.\"    Newsgroups: gmane.linux.kernel, gmane.linux.file-systems
+.\" commit 9c225f2655e36a470c4f58dbbc99244c5fc7f2d4
+.\"    Author: Linus Torvalds <torvalds@linux-foundation.org>
+.\"    Date:   Mon Mar 3 09:36:58 2014 -0800
+.\"
+.\"        vfs: atomic f_pos accesses as per POSIX
+.SH SEE ALSO
+.BR close (2),
+.BR fcntl (2),
+.BR ioctl (2),
+.BR lseek (2),
+.BR open (2),
+.BR pread (2),
+.BR readdir (2),
+.BR readlink (2),
+.BR readv (2),
+.BR select (2),
+.BR write (2),
+.BR fread (3)
diff --git a/man/man2/readahead.2 b/man/man2/readahead.2
new file mode 100644
index 000000000..e857fde66
--- /dev/null
+++ b/man/man2/readahead.2
@@ -0,0 +1,99 @@
+.\" This manpage is Copyright (C) 2004, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2004-05-40 Created by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2004-10-05 aeb, minor correction
+.\"
+.TH readahead 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+readahead \- initiate file readahead into page cache
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #define _FILE_OFFSET_BITS 64
+.B #include <fcntl.h>
+.P
+.BI "ssize_t readahead(int " fd ", off_t " offset ", size_t " count );
+.fi
+.SH DESCRIPTION
+.BR readahead ()
+initiates readahead on a file so that subsequent reads from that file will
+be satisfied from the cache, and not block on disk I/O
+(assuming the readahead was initiated early enough and that other activity
+on the system did not in the meantime flush pages from the cache).
+.P
+The
+.I fd
+argument is a file descriptor identifying the file which is
+to be read.
+The
+.I offset
+argument specifies the starting point from which data is to be read
+and
+.I count
+specifies the number of bytes to be read.
+I/O is performed in whole pages, so that
+.I offset
+is effectively rounded down to a page boundary
+and bytes are read up to the next page boundary greater than or
+equal to
+.IR "(offset+count)" .
+.BR readahead ()
+does not read beyond the end of the file.
+The file offset of the open file description referred to by the file descriptor
+.I fd
+is left unchanged.
+.SH RETURN VALUE
+On success,
+.BR readahead ()
+returns 0; on failure, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor or is not open for reading.
+.TP
+.B EINVAL
+.I fd
+does not refer to a file type to which
+.BR readahead ()
+can be applied.
+.SH VERSIONS
+On some 32-bit architectures,
+the calling signature for this system call differs,
+for the reasons described in
+.BR syscall (2).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.4.13,
+glibc 2.3.
+.SH NOTES
+.B _FILE_OFFSET_BITS
+should be defined to be 64 in code that uses a pointer to
+.BR readahead ,
+if the code is intended to be portable
+to traditional 32-bit x86 and ARM platforms where
+.BR off_t 's
+width defaults to 32 bits.
+.SH BUGS
+.BR readahead ()
+attempts to schedule the reads in the background and return immediately.
+However, it may block while it reads the filesystem metadata needed
+to locate the requested blocks.
+This occurs frequently with ext[234] on large files
+using indirect blocks instead of extents,
+giving the appearance that the call blocks until the requested data has
+been read.
+.SH SEE ALSO
+.BR lseek (2),
+.BR madvise (2),
+.BR mmap (2),
+.BR posix_fadvise (2),
+.BR read (2)
diff --git a/man/man2/readdir.2 b/man/man2/readdir.2
new file mode 100644
index 000000000..933bb30d4
--- /dev/null
+++ b/man/man2/readdir.2
@@ -0,0 +1,116 @@
+.\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Written 11 June 1995 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 22 July 1995 by Michael Chastain <mec@duracef.shout.net>:
+.\"   In 1.3.X, returns only one entry each time; return value is different.
+.\" Modified 2004-12-01, mtk, fixed headers listed in SYNOPSIS
+.\"
+.TH readdir 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+readdir \- read directory entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_readdir, unsigned int " fd ,
+.BI "            struct old_linux_dirent *" dirp ", unsigned int " count );
+.fi
+.P
+.IR Note :
+There is no definition of
+.BR "struct old_linux_dirent" ;
+see NOTES.
+.SH DESCRIPTION
+This is not the function you are interested in.
+Look at
+.BR readdir (3)
+for the POSIX conforming C library interface.
+This page documents the bare kernel system call interface,
+which is superseded by
+.BR getdents (2).
+.P
+.BR readdir ()
+reads one
+.I old_linux_dirent
+structure from the directory
+referred to by the file descriptor
+.I fd
+into the buffer pointed to by
+.IR dirp .
+The argument
+.I count
+is ignored; at most one
+.I old_linux_dirent
+structure is read.
+.P
+The
+.I old_linux_dirent
+structure is declared (privately in Linux kernel file
+.BR fs/readdir.c )
+as follows:
+.P
+.in +4n
+.EX
+struct old_linux_dirent {
+    unsigned long d_ino;     /* inode number */
+    unsigned long d_offset;  /* offset to this \fIold_linux_dirent\fP */
+    unsigned short d_namlen; /* length of this \fId_name\fP */
+    char  d_name[1];         /* filename (null\-terminated) */
+}
+.EE
+.in
+.P
+.I d_ino
+is an inode number.
+.I d_offset
+is the distance from the start of the directory to this
+.IR old_linux_dirent .
+.I d_reclen
+is the size of
+.IR d_name ,
+not counting the terminating null byte (\[aq]\e0\[aq]).
+.I d_name
+is a null-terminated filename.
+.SH RETURN VALUE
+On success, 1 is returned.
+On end of directory, 0 is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+Invalid file descriptor
+.IR fd .
+.TP
+.B EFAULT
+Argument points outside the calling process's address space.
+.TP
+.B EINVAL
+Result buffer is too small.
+.TP
+.B ENOENT
+No such directory.
+.TP
+.B ENOTDIR
+File descriptor does not refer to a directory.
+.SH VERSIONS
+You will need to define the
+.I old_linux_dirent
+structure yourself.
+However, probably you should use
+.BR readdir (3)
+instead.
+.P
+This system call does not exist on x86-64.
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR getdents (2),
+.BR readdir (3)
diff --git a/man/man2/readlink.2 b/man/man2/readlink.2
new file mode 100644
index 000000000..da671a9be
--- /dev/null
+++ b/man/man2/readlink.2
@@ -0,0 +1,331 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" And Copyright (C) 2011 Guillem Jover <guillem@hadrons.org>
+.\" And Copyright (C) 2006, 2014 Michael Kerrisk
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)readlink.2	6.8 (Berkeley) 3/10/91
+.\"
+.\" Modified Sat Jul 24 00:10:21 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Tue Jul  9 23:55:17 1996 by aeb
+.\" Modified Fri Jan 24 00:26:00 1997 by aeb
+.\" 2011-09-20, Guillem Jover <guillem@hadrons.org>:
+.\"     Added text on dynamically allocating buffer + example program
+.\"
+.TH readlink 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+readlink, readlinkat \- read value of a symbolic link
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "ssize_t readlink(const char *restrict " pathname ", char *restrict " buf ,
+.BI "                 size_t " bufsiz );
+.P
+.BR "#include <fcntl.h>            " "/* Definition of " AT_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "ssize_t readlinkat(int " dirfd ", const char *restrict " pathname ,
+.BI "                 char *restrict " buf ", size_t " bufsiz );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR readlink ():
+.nf
+    _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.P
+.BR readlinkat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+.BR readlink ()
+places the contents of the symbolic link
+.I pathname
+in the buffer
+.IR buf ,
+which has size
+.IR bufsiz .
+.BR readlink ()
+does not append a terminating null byte to
+.IR buf .
+It will (silently) truncate the contents (to a length of
+.I bufsiz
+characters), in case the buffer is too small to hold all of the contents.
+.SS readlinkat()
+The
+.BR readlinkat ()
+system call operates in exactly the same way as
+.BR readlink (),
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR readlink ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR readlink ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+Since Linux 2.6.39,
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+.I pathname
+can be an empty string,
+in which case the call operates on the symbolic link referred to by
+.I dirfd
+(which should have been obtained using
+.BR open (2)
+with the
+.B O_PATH
+and
+.B O_NOFOLLOW
+flags).
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR readlinkat ().
+.SH RETURN VALUE
+On success, these calls return the number of bytes placed in
+.IR buf .
+(If the returned value equals
+.IR bufsiz ,
+then truncation may have occurred.)
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission is denied for a component of the path prefix.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( readlinkat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I buf
+extends outside the process's allocated address space.
+.TP
+.B EINVAL
+.I bufsiz
+is not positive.
+.\" At the glibc level, bufsiz is unsigned, so this error can only occur
+.\" if bufsiz==0.  However, the in the kernel syscall, bufsiz is signed,
+.\" and this error can also occur if bufsiz < 0.
+.\" See: http://thread.gmane.org/gmane.linux.man/380
+.\" Subject: [patch 0/3] [RFC] kernel/glibc mismatch of "readlink" syscall?
+.TP
+.B EINVAL
+The named file (i.e., the final filename component of
+.IR pathname )
+is not a symbolic link.
+.TP
+.B EIO
+An I/O error occurred while reading from the filesystem.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in translating the pathname.
+.TP
+.B ENAMETOOLONG
+A pathname, or a component of a pathname, was too long.
+.TP
+.B ENOENT
+The named file does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component of the path prefix is not a directory.
+.TP
+.B ENOTDIR
+.RB ( readlinkat ())
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR readlink ()
+4.4BSD
+(first appeared in 4.2BSD),
+POSIX.1-2001, POSIX.1-2008.
+.TP
+.BR readlinkat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.P
+Up to and including glibc 2.4, the return type of
+.BR readlink ()
+was declared as
+.IR int .
+Nowadays, the return type is declared as
+.IR ssize_t ,
+as (newly) required in POSIX.1-2001.
+.SS glibc
+On older kernels where
+.BR readlinkat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR readlink ().
+When
+.I pathname
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.I /proc/self/fd
+that corresponds to the
+.I dirfd
+argument.
+.SH NOTES
+Using a statically sized buffer might not provide enough room for the
+symbolic link contents.
+The required size for the buffer can be obtained from the
+.I stat.st_size
+value returned by a call to
+.BR lstat (2)
+on the link.
+However, the number of bytes written by
+.BR readlink ()
+and
+.BR readlinkat ()
+should be checked to make sure that the size of the
+symbolic link did not increase between the calls.
+Dynamically allocating the buffer for
+.BR readlink ()
+and
+.BR readlinkat ()
+also addresses a common portability problem when using
+.B PATH_MAX
+for the buffer size,
+as this constant is not guaranteed to be defined per POSIX
+if the system does not have such limit.
+.SH EXAMPLES
+The following program allocates the buffer needed by
+.BR readlink ()
+dynamically from the information provided by
+.BR lstat (2),
+falling back to a buffer of size
+.B PATH_MAX
+in cases where
+.BR lstat (2)
+reports a size of zero.
+.P
+.\" SRC BEGIN (readlink.c)
+.EX
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    char         *buf;
+    ssize_t      nbytes, bufsiz;
+    struct stat  sb;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <pathname>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (lstat(argv[1], &sb) == \-1) {
+        perror("lstat");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Add one to the link size, so that we can determine whether
+       the buffer returned by readlink() was truncated. */
+\&
+    bufsiz = sb.st_size + 1;
+\&
+    /* Some magic symlinks under (for example) /proc and /sys
+       report \[aq]st_size\[aq] as zero. In that case, take PATH_MAX as
+       a "good enough" estimate. */
+\&
+    if (sb.st_size == 0)
+        bufsiz = PATH_MAX;
+\&
+    buf = malloc(bufsiz);
+    if (buf == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    nbytes = readlink(argv[1], buf, bufsiz);
+    if (nbytes == \-1) {
+        perror("readlink");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Print only \[aq]nbytes\[aq] of \[aq]buf\[aq], as it doesn't contain a terminating
+       null byte (\[aq]\e0\[aq]). */
+    printf("\[aq]%s\[aq] points to \[aq]%.*s\[aq]\en", argv[1], (int) nbytes, buf);
+\&
+    /* If the return value was equal to the buffer size, then
+       the link target was larger than expected (perhaps because the
+       target was changed between the call to lstat() and the call to
+       readlink()). Warn the user that the returned target may have
+       been truncated. */
+\&
+    if (nbytes == bufsiz)
+        printf("(Returned buffer may have been truncated)\en");
+\&
+    free(buf);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR readlink (1),
+.BR lstat (2),
+.BR stat (2),
+.BR symlink (2),
+.BR realpath (3),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/readlinkat.2 b/man/man2/readlinkat.2
new file mode 100644
index 000000000..b29d1b541
--- /dev/null
+++ b/man/man2/readlinkat.2
@@ -0,0 +1 @@
+.so man2/readlink.2
diff --git a/man/man2/readv.2 b/man/man2/readv.2
new file mode 100644
index 000000000..d39f2b9b9
--- /dev/null
+++ b/man/man2/readv.2
@@ -0,0 +1,427 @@
+.\" Copyright (C) 2007, 2010 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 18:34:44 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Merged readv.[23], 2002-10-17, aeb
+.\" 2007-04-30 mtk, A fairly major rewrite to fix errors and
+.\"     add more details.
+.\" 2010-11-16, mtk, Added documentation of preadv() and pwritev()
+.\"
+.TH readv 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+readv, writev, preadv, pwritev, preadv2, pwritev2 \-
+read or write data into multiple buffers
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/uio.h>
+.P
+.BI "ssize_t readv(int " fd ", const struct iovec *" iov ", int " iovcnt );
+.BI "ssize_t writev(int " fd ", const struct iovec *" iov ", int " iovcnt );
+.P
+.BI "ssize_t preadv(int " fd ", const struct iovec *" iov ", int " iovcnt ,
+.BI "                off_t " offset );
+.BI "ssize_t pwritev(int " fd ", const struct iovec *" iov ", int " iovcnt ,
+.BI "                off_t " offset );
+.P
+.BI "ssize_t preadv2(int " fd ", const struct iovec *" iov ", int " iovcnt ,
+.BI "                off_t " offset ", int " flags );
+.BI "ssize_t pwritev2(int " fd ", const struct iovec *" iov ", int " iovcnt ,
+.BI "                off_t " offset ", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR preadv (),
+.BR pwritev ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR readv ()
+system call reads
+.I iovcnt
+buffers from the file associated with the file descriptor
+.I fd
+into the buffers described by
+.I iov
+("scatter input").
+.P
+The
+.BR writev ()
+system call writes
+.I iovcnt
+buffers of data described by
+.I iov
+to the file associated with the file descriptor
+.I fd
+("gather output").
+.P
+The pointer
+.I iov
+points to an array of
+.I iovec
+structures,
+described in
+.BR iovec (3type).
+.P
+The
+.BR readv ()
+system call works just like
+.BR read (2)
+except that multiple buffers are filled.
+.P
+The
+.BR writev ()
+system call works just like
+.BR write (2)
+except that multiple buffers are written out.
+.P
+Buffers are processed in array order.
+This means that
+.BR readv ()
+completely fills
+.I iov[0]
+before proceeding to
+.IR iov[1] ,
+and so on.
+(If there is insufficient data, then not all buffers pointed to by
+.I iov
+may be filled.)
+Similarly,
+.BR writev ()
+writes out the entire contents of
+.I iov[0]
+before proceeding to
+.IR iov[1] ,
+and so on.
+.P
+The data transfers performed by
+.BR readv ()
+and
+.BR writev ()
+are atomic: the data written by
+.\" Regarding atomicity, see https://bugzilla.kernel.org/show_bug.cgi?id=10596
+.BR writev ()
+is written as a single block that is not intermingled with output
+from writes in other processes;
+analogously,
+.BR readv ()
+is guaranteed to read a contiguous block of data from the file,
+regardless of read operations performed in other threads or processes
+that have file descriptors referring to the same open file description
+(see
+.BR open (2)).
+.SS preadv() and pwritev()
+The
+.BR preadv ()
+system call combines the functionality of
+.BR readv ()
+and
+.BR pread (2).
+It performs the same task as
+.BR readv (),
+but adds a fourth argument,
+.IR offset ,
+which specifies the file offset at which the input operation
+is to be performed.
+.P
+The
+.BR pwritev ()
+system call combines the functionality of
+.BR writev ()
+and
+.BR pwrite (2).
+It performs the same task as
+.BR writev (),
+but adds a fourth argument,
+.IR offset ,
+which specifies the file offset at which the output operation
+is to be performed.
+.P
+The file offset is not changed by these system calls.
+The file referred to by
+.I fd
+must be capable of seeking.
+.SS preadv2() and pwritev2()
+These system calls are similar to
+.BR preadv ()
+and
+.BR pwritev ()
+calls, but add a fifth argument,
+.IR flags ,
+which modifies the behavior on a per-call basis.
+.P
+Unlike
+.BR preadv ()
+and
+.BR pwritev (),
+if the
+.I offset
+argument is \-1, then the current file offset is used and updated.
+.P
+The
+.I flags
+argument contains a bitwise OR of zero or more of the following flags:
+.TP
+.BR RWF_DSYNC " (since Linux 4.7)"
+.\" commit e864f39569f4092c2b2bc72c773b6e486c7e3bd9
+Provide a per-write equivalent of the
+.B O_DSYNC
+.BR open (2)
+flag.
+This flag is meaningful only for
+.BR pwritev2 (),
+and its effect applies only to the data range written by the system call.
+.TP
+.BR RWF_HIPRI " (since Linux 4.6)"
+High priority read/write.
+Allows block-based filesystems to use polling of the device,
+which provides lower latency, but may use additional resources.
+(Currently, this feature is usable only on a file descriptor opened using the
+.B O_DIRECT
+flag.)
+.TP
+.BR RWF_SYNC " (since Linux 4.7)"
+.\" commit e864f39569f4092c2b2bc72c773b6e486c7e3bd9
+Provide a per-write equivalent of the
+.B O_SYNC
+.BR open (2)
+flag.
+This flag is meaningful only for
+.BR pwritev2 (),
+and its effect applies only to the data range written by the system call.
+.TP
+.BR RWF_NOWAIT " (since Linux 4.14)"
+.\" commit 3239d834847627b6634a4139cf1dc58f6f137a46
+.\" commit 91f9943e1c7b6638f27312d03fe71fcc67b23571
+Do not wait for data which is not immediately available.
+If this flag is specified, the
+.BR preadv2 ()
+system call will return instantly if it would have to read data from
+the backing storage or wait for a lock.
+If some data was successfully read, it will return the number of bytes read.
+If no bytes were read, it will return \-1 and set
+.I errno
+to
+.B EAGAIN
+(but see
+.BR BUGS ).
+Currently, this flag is meaningful only for
+.BR preadv2 ().
+.TP
+.BR RWF_APPEND " (since Linux 4.16)"
+.\" commit e1fc742e14e01d84d9693c4aca4ab23da65811fb
+Provide a per-write equivalent of the
+.B O_APPEND
+.BR open (2)
+flag.
+This flag is meaningful only for
+.BR pwritev2 (),
+and its effect applies only to the data range written by the system call.
+The
+.I offset
+argument does not affect the write operation;
+the data is always appended to the end of the file.
+However, if the
+.I offset
+argument is \-1, the current file offset is updated.
+.SH RETURN VALUE
+On success,
+.BR readv (),
+.BR preadv (),
+and
+.BR preadv2 ()
+return the number of bytes read;
+.BR writev (),
+.BR pwritev (),
+and
+.BR pwritev2 ()
+return the number of bytes written.
+.P
+Note that it is not an error for a successful call to transfer fewer bytes
+than requested (see
+.BR read (2)
+and
+.BR write (2)).
+.P
+On error, \-1 is returned, and \fIerrno\fP is set to indicate the error.
+.SH ERRORS
+The errors are as given for
+.BR read (2)
+and
+.BR write (2).
+Furthermore,
+.BR preadv (),
+.BR preadv2 (),
+.BR pwritev (),
+and
+.BR pwritev2 ()
+can also fail for the same reasons as
+.BR lseek (2).
+Additionally, the following errors are defined:
+.TP
+.B EINVAL
+The sum of the
+.I iov_len
+values overflows an
+.I ssize_t
+value.
+.TP
+.B EINVAL
+The vector count,
+.IR iovcnt ,
+is less than zero or greater than the permitted maximum.
+.TP
+.B EOPNOTSUPP
+An unknown flag is specified in \fIflags\fP.
+.SH VERSIONS
+.SS C library/kernel differences
+The raw
+.BR preadv ()
+and
+.BR pwritev ()
+system calls have call signatures that differ slightly from that of the
+corresponding GNU C library wrapper functions shown in the SYNOPSIS.
+The final argument,
+.IR offset ,
+is unpacked by the wrapper functions into two arguments in the system calls:
+.P
+.BI "    unsigned long " pos_l ", unsigned long " pos
+.P
+These arguments contain, respectively, the low order and high order 32 bits of
+.IR offset .
+.SH STANDARDS
+.TP
+.BR readv ()
+.TQ
+.BR writev ()
+POSIX.1-2008.
+.TP
+.BR preadv ()
+.TQ
+.BR pwritev ()
+BSD.
+.TP
+.BR preadv2 ()
+.TQ
+.BR pwritev2 ()
+Linux.
+.SH HISTORY
+.TP
+.BR readv ()
+.TQ
+.BR writev ()
+POSIX.1-2001,
+4.4BSD (first appeared in 4.2BSD).
+.\" Linux libc5 used \fIsize_t\fP as the type of the \fIiovcnt\fP argument,
+.\" and \fIint\fP as the return type.
+.\" The readv/writev system calls were buggy before Linux 1.3.40.
+.\" (Says release.libc.)
+.P
+.BR preadv (),
+.BR pwritev ():
+Linux 2.6.30,
+glibc 2.10.
+.P
+.BR preadv2 (),
+.BR pwritev2 ():
+Linux 4.6,
+glibc 2.26.
+.SS Historical C library/kernel differences
+To deal with the fact that
+.B IOV_MAX
+was so low on early versions of Linux,
+the glibc wrapper functions for
+.BR readv ()
+and
+.BR writev ()
+did some extra work if they detected that the underlying kernel
+system call failed because this limit was exceeded.
+In the case of
+.BR readv (),
+the wrapper function allocated a temporary buffer large enough
+for all of the items specified by
+.IR iov ,
+passed that buffer in a call to
+.BR read (2),
+copied data from the buffer to the locations specified by the
+.I iov_base
+fields of the elements of
+.IR iov ,
+and then freed the buffer.
+The wrapper function for
+.BR writev ()
+performed the analogous task using a temporary buffer and a call to
+.BR write (2).
+.P
+The need for this extra effort in the glibc wrapper functions
+went away with Linux 2.2 and later.
+However, glibc continued to provide this behavior until glibc 2.10.
+Starting with glibc 2.9,
+the wrapper functions provide this behavior only if the library detects
+that the system is running a Linux kernel older than Linux 2.6.18
+(an arbitrarily selected kernel version).
+And since glibc 2.20
+(which requires a minimum of Linux 2.6.32),
+the glibc wrapper functions always just directly invoke the system calls.
+.SH NOTES
+POSIX.1 allows an implementation to place a limit on
+the number of items that can be passed in
+.IR iov .
+An implementation can advertise its limit by defining
+.B IOV_MAX
+in
+.I <limits.h>
+or at run time via the return value from
+.IR sysconf(_SC_IOV_MAX) .
+On modern Linux systems, the limit is 1024.
+Back in Linux 2.0 days, this limit was 16.
+.\"
+.\"
+.SH BUGS
+Linux 5.9 and Linux 5.10 have a bug where
+.BR preadv2 ()
+with the
+.B RWF_NOWAIT
+flag may return 0 even when not at end of file.
+.\" See
+.\" <https://lore.kernel.org/linux-fsdevel/fea8b16d-5a69-40f9-b123-e84dcd6e8f2e@www.fastmail.com/T/#u>
+.\" The bug was introduced in
+.\"    efa8480a831 fs: RWF_NOWAIT should imply IOCB_NOIO
+.\"and fixed in
+.\"    06c0444290 mm/filemap.c: generic_file_buffered_read() now uses find_get_pages_contig
+.SH EXAMPLES
+The following code sample demonstrates the use of
+.BR writev ():
+.P
+.in +4n
+.EX
+char          *str0 = "hello ";
+char          *str1 = "world\en";
+ssize_t       nwritten;
+struct iovec  iov[2];
+\&
+iov[0].iov_base = str0;
+iov[0].iov_len = strlen(str0);
+iov[1].iov_base = str1;
+iov[1].iov_len = strlen(str1);
+\&
+nwritten = writev(STDOUT_FILENO, iov, 2);
+.EE
+.in
+.SH SEE ALSO
+.BR pread (2),
+.BR read (2),
+.BR write (2)
diff --git a/man/man2/reboot.2 b/man/man2/reboot.2
new file mode 100644
index 000000000..6d106e3dc
--- /dev/null
+++ b/man/man2/reboot.2
@@ -0,0 +1,241 @@
+.\" Copyright (c) 1998 Andries Brouwer (aeb@cwi.nl), 24 September 1998
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.TH reboot 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+reboot \- reboot or enable/disable Ctrl-Alt-Del
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.RB "/* Since Linux 2.1.30 there are symbolic names " LINUX_REBOOT_*
+   for the constants and a fourth argument to the call: */
+.P
+.BR "#include <linux/reboot.h>  " \
+"/* Definition of " LINUX_REBOOT_* " constants */"
+.BR "#include <sys/syscall.h>   " "/* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_reboot, int " magic ", int " magic2 ", int " op ", void *" arg );
+.P
+/* Under glibc and most alternative libc's (including uclibc, dietlibc,
+   musl and a few others), some of the constants involved have gotten
+.RB "   symbolic names " RB_* ", and the library call is a 1-argument"
+   wrapper around the system call: */
+.P
+.BR "#include <sys/reboot.h>    " "/* Definition of " RB_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int reboot(int " op );
+.fi
+.SH DESCRIPTION
+The
+.BR reboot ()
+call reboots the system, or enables/disables the reboot keystroke
+(abbreviated CAD, since the default is Ctrl-Alt-Delete;
+it can be changed using
+.BR loadkeys (1)).
+.P
+This system call fails (with the error
+.BR EINVAL )
+unless
+.I magic
+equals
+.B LINUX_REBOOT_MAGIC1
+(that is, 0xfee1dead) and
+.I magic2
+equals
+.B LINUX_REBOOT_MAGIC2
+(that is, 0x28121969).
+However, since Linux 2.1.17 also
+.B LINUX_REBOOT_MAGIC2A
+(that is, 0x05121996)
+and since Linux 2.1.97 also
+.B LINUX_REBOOT_MAGIC2B
+(that is, 0x16041998)
+and since Linux 2.5.71 also
+.B LINUX_REBOOT_MAGIC2C
+(that is, 0x20112000)
+are permitted as values for
+.IR magic2 .
+(The hexadecimal values of these constants are meaningful.)
+.P
+The
+.I op
+argument can have the following values:
+.TP
+.B LINUX_REBOOT_CMD_CAD_OFF
+.RB ( RB_DISABLE_CAD ,
+0).
+CAD is disabled.
+This means that the CAD keystroke will cause a
+.B SIGINT
+signal to be
+sent to init (process 1), whereupon this process may decide upon a
+proper action (maybe: kill all processes, sync, reboot).
+.TP
+.B LINUX_REBOOT_CMD_CAD_ON
+.RB ( RB_ENABLE_CAD ,
+0x89abcdef).
+CAD is enabled.
+This means that the CAD keystroke will immediately cause
+the action associated with
+.BR LINUX_REBOOT_CMD_RESTART .
+.TP
+.B LINUX_REBOOT_CMD_HALT
+.RB ( RB_HALT_SYSTEM ,
+0xcdef0123; since Linux 1.1.76).
+The message "System halted." is printed, and the system is halted.
+Control is given to the ROM monitor, if there is one.
+If not preceded by a
+.BR sync (2),
+data will be lost.
+.TP
+.B LINUX_REBOOT_CMD_KEXEC
+.RB ( RB_KEXEC ,
+0x45584543, since Linux 2.6.13).
+Execute a kernel that has been loaded earlier with
+.BR kexec_load (2).
+This option is available only if the kernel was configured with
+.BR CONFIG_KEXEC .
+.TP
+.B LINUX_REBOOT_CMD_POWER_OFF
+.RB ( RB_POWER_OFF ,
+0x4321fedc; since Linux 2.1.30).
+The message "Power down." is printed, the system is stopped,
+and all power is removed from the system, if possible.
+If not preceded by a
+.BR sync (2),
+data will be lost.
+.TP
+.B LINUX_REBOOT_CMD_RESTART
+.RB ( RB_AUTOBOOT ,
+0x1234567).
+The message "Restarting system." is printed, and a default
+restart is performed immediately.
+If not preceded by a
+.BR sync (2),
+data will be lost.
+.TP
+.B LINUX_REBOOT_CMD_RESTART2
+(0xa1b2c3d4; since Linux 2.1.30).
+The message "Restarting system with command \[aq]%s\[aq]" is printed,
+and a restart (using the command string given in
+.IR arg )
+is performed immediately.
+If not preceded by a
+.BR sync (2),
+data will be lost.
+.TP
+.B LINUX_REBOOT_CMD_SW_SUSPEND
+.RB ( RB_SW_SUSPEND ,
+0xd000fce1; since Linux 2.5.18).
+The system is suspended (hibernated) to disk.
+This option is available only if the kernel was configured with
+.BR CONFIG_HIBERNATION .
+.P
+Only the superuser may call
+.BR reboot ().
+.P
+The precise effect of the above actions depends on the architecture.
+For the i386 architecture, the additional argument does not do
+anything at present (2.1.122), but the type of reboot can be
+determined by kernel command-line arguments ("reboot=...") to be
+either warm or cold, and either hard or through the BIOS.
+.\"
+.SS Behavior inside PID namespaces
+.\" commit cf3f89214ef6a33fad60856bc5ffd7bb2fc4709b
+.\" see also commit 923c7538236564c46ee80c253a416705321f13e3
+Since Linux 3.4,
+if
+.BR reboot ()
+is called
+from a PID namespace other than the initial PID namespace
+with one of the
+.I op
+values listed below,
+it performs a "reboot" of that namespace:
+the "init" process of the PID namespace is immediately terminated,
+with the effects described in
+.BR pid_namespaces (7).
+.P
+The values that can be supplied in
+.I op
+when calling
+.BR reboot ()
+in this case are as follows:
+.TP
+.B LINUX_REBOOT_CMD_RESTART
+.TQ
+.B LINUX_REBOOT_CMD_RESTART2
+The "init" process is terminated,
+and
+.BR wait (2)
+in the parent process reports that the child was killed with a
+.B SIGHUP
+signal.
+.TP
+.B LINUX_REBOOT_CMD_POWER_OFF
+.TQ
+.B LINUX_REBOOT_CMD_HALT
+The "init" process is terminated,
+and
+.BR wait (2)
+in the parent process reports that the child was killed with a
+.B SIGINT
+signal.
+.P
+For the other
+.I op
+values,
+.BR reboot ()
+returns \-1 and
+.I errno
+is set to
+.BR EINVAL .
+.SH RETURN VALUE
+For the values of
+.I op
+that stop or restart the system,
+a successful call to
+.BR reboot ()
+does not return.
+For the other
+.I op
+values, zero is returned on success.
+In all cases, \-1 is returned on failure, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Problem with getting user-space data under
+.BR LINUX_REBOOT_CMD_RESTART2 .
+.TP
+.B EINVAL
+Bad magic numbers or
+.IR op .
+.TP
+.B EPERM
+The calling process has insufficient privilege to call
+.BR reboot ();
+the caller must have the
+.B CAP_SYS_BOOT
+inside its user namespace.
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR systemctl (1),
+.BR systemd (1),
+.BR kexec_load (2),
+.BR sync (2),
+.BR bootparam (7),
+.BR capabilities (7),
+.BR ctrlaltdel (8),
+.BR halt (8),
+.BR shutdown (8)
diff --git a/man/man2/recv.2 b/man/man2/recv.2
new file mode 100644
index 000000000..294eca384
--- /dev/null
+++ b/man/man2/recv.2
@@ -0,0 +1,563 @@
+.\" Copyright (c) 1983, 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     $Id: recv.2,v 1.3 1999/05/13 11:33:38 freitag Exp $
+.\"
+.\" Modified Sat Jul 24 00:22:20 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 17:45:19 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998,1999 by Andi Kleen
+.\" 2001-06-19 corrected SO_EE_OFFENDER, bug report by James Hawtin
+.\"
+.TH recv 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+recv, recvfrom, recvmsg \- receive a message from a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "ssize_t recv(int " sockfd ", void " buf [. len "], size_t " len ,
+.BI "                 int " flags );
+.BI "ssize_t recvfrom(int " sockfd ", void " buf "[restrict ." len "], size_t " len ,
+.BI "                 int " flags ,
+.BI "                 struct sockaddr *_Nullable restrict " src_addr ,
+.BI "                 socklen_t *_Nullable restrict " addrlen );
+.BI "ssize_t recvmsg(int " sockfd ", struct msghdr *" msg ", int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR recv (),
+.BR recvfrom (),
+and
+.BR recvmsg ()
+calls are used to receive messages from a socket.
+They may be used
+to receive data on both connectionless and connection-oriented sockets.
+This page first describes common features of all three system calls,
+and then describes the differences between the calls.
+.P
+The only difference between
+.BR recv ()
+and
+.BR read (2)
+is the presence of
+.IR flags .
+With a zero
+.I flags
+argument,
+.BR recv ()
+is generally equivalent to
+.BR read (2)
+(but see NOTES).
+Also, the following call
+.P
+.in +4n
+.EX
+recv(sockfd, buf, len, flags);
+.EE
+.in
+.P
+is equivalent to
+.P
+.in +4n
+.EX
+recvfrom(sockfd, buf, len, flags, NULL, NULL);
+.EE
+.in
+.P
+All three calls return the length of the message on successful
+completion.
+If a message is too long to fit in the supplied buffer, excess
+bytes may be discarded depending on the type of socket the message is
+received from.
+.P
+If no messages are available at the socket, the receive calls wait for a
+message to arrive, unless the socket is nonblocking (see
+.BR fcntl (2)),
+in which case the value \-1 is returned and
+.I errno
+is set to
+.BR EAGAIN " or " EWOULDBLOCK .
+The receive calls normally return any data available, up to the requested
+amount, rather than waiting for receipt of the full amount requested.
+.P
+An application can use
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7)
+to determine when more data arrives on a socket.
+.SS The flags argument
+The
+.I flags
+argument is formed by ORing one or more of the following values:
+.TP
+.BR MSG_CMSG_CLOEXEC " (" recvmsg "() only; since Linux 2.6.23)"
+Set the close-on-exec flag for the file descriptor received
+via a UNIX domain file descriptor using the
+.B SCM_RIGHTS
+operation (described in
+.BR unix (7)).
+This flag is useful for the same reasons as the
+.B O_CLOEXEC
+flag of
+.BR open (2).
+.TP
+.BR MSG_DONTWAIT " (since Linux 2.2)"
+Enables nonblocking operation; if the operation would block,
+the call fails with the error
+.BR EAGAIN " or " EWOULDBLOCK .
+This provides similar behavior to setting the
+.B O_NONBLOCK
+flag (via the
+.BR fcntl (2)
+.B F_SETFL
+operation), but differs in that
+.B MSG_DONTWAIT
+is a per-call option, whereas
+.B O_NONBLOCK
+is a setting on the open file description (see
+.BR open (2)),
+which will affect all threads in the calling process
+as well as other processes that hold file descriptors
+referring to the same open file description.
+.TP
+.BR MSG_ERRQUEUE " (since Linux 2.2)"
+This flag
+specifies that queued errors should be received from the socket error queue.
+The error is passed in
+an ancillary message with a type dependent on the protocol (for IPv4
+.BR IP_RECVERR ).
+The user should supply a buffer of sufficient size.
+See
+.BR cmsg (3)
+and
+.BR ip (7)
+for more information.
+The payload of the original packet that caused the error
+is passed as normal data via
+.IR msg_iovec .
+The original destination address of the datagram that caused the error
+is supplied via
+.IR msg_name .
+.IP
+The error is supplied in a
+.I sock_extended_err
+structure:
+.IP
+.in +4n
+.EX
+#define SO_EE_ORIGIN_NONE    0
+#define SO_EE_ORIGIN_LOCAL   1
+#define SO_EE_ORIGIN_ICMP    2
+#define SO_EE_ORIGIN_ICMP6   3
+\&
+struct sock_extended_err
+{
+    uint32_t ee_errno;   /* Error number */
+    uint8_t  ee_origin;  /* Where the error originated */
+    uint8_t  ee_type;    /* Type */
+    uint8_t  ee_code;    /* Code */
+    uint8_t  ee_pad;     /* Padding */
+    uint32_t ee_info;    /* Additional information */
+    uint32_t ee_data;    /* Other data */
+    /* More data may follow */
+};
+\&
+struct sockaddr *SO_EE_OFFENDER(struct sock_extended_err *);
+.EE
+.in
+.IP
+.I ee_errno
+contains the
+.I errno
+number of the queued error.
+.I ee_origin
+is the origin code of where the error originated.
+The other fields are protocol-specific.
+The macro
+.B SO_EE_OFFENDER
+returns a pointer to the address of the network object
+where the error originated from given a pointer to the ancillary message.
+If this address is not known, the
+.I sa_family
+member of the
+.I sockaddr
+contains
+.B AF_UNSPEC
+and the other fields of the
+.I sockaddr
+are undefined.
+The payload of the packet that caused the error is passed as normal data.
+.IP
+For local errors, no address is passed (this
+can be checked with the
+.I cmsg_len
+member of the
+.IR cmsghdr ).
+For error receives,
+the
+.B MSG_ERRQUEUE
+flag is set in the
+.IR msghdr .
+After an error has been passed, the pending socket error
+is regenerated based on the next queued error and will be passed
+on the next socket operation.
+.TP
+.B MSG_OOB
+This flag requests receipt of out-of-band data that would not be received
+in the normal data stream.
+Some protocols place expedited data
+at the head of the normal data queue, and thus this flag cannot
+be used with such protocols.
+.TP
+.B MSG_PEEK
+This flag causes the receive operation to
+return data from the beginning of the
+receive queue without removing that data from the queue.
+Thus, a
+subsequent receive call will return the same data.
+.TP
+.BR MSG_TRUNC " (since Linux 2.2)"
+For raw
+.RB ( AF_PACKET ),
+Internet datagram (since Linux 2.4.27/2.6.8),
+netlink (since Linux 2.6.22),
+and UNIX datagram as well as sequenced-packet
+.\" commit 9f6f9af7694ede6314bed281eec74d588ba9474f
+(since Linux 3.4) sockets:
+return the real length of the packet or datagram,
+even when it was longer than the passed buffer.
+.IP
+For use with Internet stream sockets, see
+.BR tcp (7).
+.TP
+.BR MSG_WAITALL " (since Linux 2.2)"
+This flag requests that the operation block until the full request is
+satisfied.
+However, the call may still return less data than requested if
+a signal is caught, an error or disconnect occurs, or the next data to be
+received is of a different type than that returned.
+This flag has no effect for datagram sockets.
+.\"
+.SS recvfrom()
+.BR recvfrom ()
+places the received message into the buffer
+.IR buf .
+The caller must specify the size of the buffer in
+.IR len .
+.P
+If
+.I src_addr
+is not NULL,
+and the underlying protocol provides the source address of the message,
+that source address is placed in the buffer pointed to by
+.IR src_addr .
+.\" (Note: for datagram sockets in both the UNIX and Internet domains,
+.\" .I src_addr
+.\" is filled in.
+.\" .I src_addr
+.\" is also filled in for stream sockets in the UNIX domain, but is not
+.\" filled in for stream sockets in the Internet domain.)
+.\" [The above notes on AF_UNIX and AF_INET sockets apply as at
+.\" Kernel 2.4.18. (MTK, 22 Jul 02)]
+In this case,
+.I addrlen
+is a value-result argument.
+Before the call,
+it should be initialized to the size of the buffer associated with
+.IR src_addr .
+Upon return,
+.I addrlen
+is updated to contain the actual size of the source address.
+The returned address is truncated if the buffer provided is too small;
+in this case,
+.I addrlen
+will return a value greater than was supplied to the call.
+.P
+If the caller is not interested in the source address,
+.I src_addr
+and
+.I addrlen
+should be specified as NULL.
+.\"
+.SS recv()
+The
+.BR recv ()
+call is normally used only on a
+.I connected
+socket (see
+.BR connect (2)).
+It is equivalent to the call:
+.P
+.in +4n
+.EX
+recvfrom(fd, buf, len, flags, NULL, 0);
+.EE
+.in
+.\"
+.SS recvmsg()
+The
+.BR recvmsg ()
+call uses a
+.I msghdr
+structure to minimize the number of directly supplied arguments.
+This structure is defined as follows in
+.IR <sys/socket.h> :
+.P
+.in +4n
+.EX
+struct msghdr {
+    void         *msg_name;       /* Optional address */
+    socklen_t     msg_namelen;    /* Size of address */
+    struct iovec *msg_iov;        /* Scatter/gather array */
+    size_t        msg_iovlen;     /* # elements in msg_iov */
+    void         *msg_control;    /* Ancillary data, see below */
+    size_t        msg_controllen; /* Ancillary data buffer len */
+    int           msg_flags;      /* Flags on received message */
+};
+.EE
+.in
+.P
+The
+.I msg_name
+field points to a caller-allocated buffer that is used to
+return the source address if the socket is unconnected.
+The caller should set
+.I msg_namelen
+to the size of this buffer before this call;
+upon return from a successful call,
+.I msg_namelen
+will contain the length of the returned address.
+If the application does not need to know the source address,
+.I msg_name
+can be specified as NULL.
+.P
+The fields
+.I msg_iov
+and
+.I msg_iovlen
+describe scatter-gather locations, as discussed in
+.BR readv (2).
+.P
+The field
+.IR msg_control ,
+which has length
+.IR msg_controllen ,
+points to a buffer for other protocol control-related messages or
+miscellaneous ancillary data.
+When
+.BR recvmsg ()
+is called,
+.I msg_controllen
+should contain the length of the available buffer in
+.IR msg_control ;
+upon return from a successful call it will contain the length
+of the control message sequence.
+.P
+The messages are of the form:
+.P
+.in +4n
+.EX
+struct cmsghdr {
+    size_t cmsg_len;    /* Data byte count, including header
+                           (type is socklen_t in POSIX) */
+    int    cmsg_level;  /* Originating protocol */
+    int    cmsg_type;   /* Protocol\-specific type */
+/* followed by
+    unsigned char cmsg_data[]; */
+};
+.EE
+.in
+.P
+Ancillary data should be accessed only by the macros defined in
+.BR cmsg (3).
+.P
+As an example, Linux uses this ancillary data mechanism to pass extended
+errors, IP options, or file descriptors over UNIX domain sockets.
+For further information on the use of ancillary data in various
+socket domains, see
+.BR unix (7)
+and
+.BR ip (7).
+.P
+The
+.I msg_flags
+field in the
+.I msghdr
+is set on return of
+.BR recvmsg ().
+It can contain several flags:
+.TP
+.B MSG_EOR
+indicates end-of-record; the data returned completed a record (generally
+used with sockets of type
+.BR SOCK_SEQPACKET ).
+.TP
+.B MSG_TRUNC
+indicates that the trailing portion of a datagram was discarded because the
+datagram was larger than the buffer supplied.
+.TP
+.B MSG_CTRUNC
+indicates that some control data was discarded due to lack of space in the
+buffer for ancillary data.
+.TP
+.B MSG_OOB
+is returned to indicate that expedited or out-of-band data was received.
+.TP
+.B MSG_ERRQUEUE
+indicates that no data was received but an extended error from the socket
+error queue.
+.TP
+.BR MSG_CMSG_CLOEXEC " (since Linux 2.6.23)"
+.\" commit 4a19542e5f694cd408a32c3d9dc593ba9366e2d7
+indicates that
+.B MSG_CMSG_CLOEXEC
+was specified in the
+.I flags
+argument of
+.BR recvmsg ().
+.SH RETURN VALUE
+These calls return the number of bytes received, or \-1
+if an error occurred.
+In the event of an error,
+.I errno
+is set to indicate the error.
+.P
+When a stream socket peer has performed an orderly shutdown,
+the return value will be 0 (the traditional "end-of-file" return).
+.P
+Datagram sockets in various domains (e.g., the UNIX and Internet domains)
+permit zero-length datagrams.
+When such a datagram is received, the return value is 0.
+.P
+The value 0 may also be returned if the requested number of bytes
+to receive from a stream socket was 0.
+.SH ERRORS
+These are some standard errors generated by the socket layer.
+Additional errors
+may be generated and returned from the underlying protocol modules;
+see their manual pages.
+.TP
+.BR EAGAIN " or " EWOULDBLOCK
+.\" Actually EAGAIN on Linux
+The socket is marked nonblocking and the receive operation
+would block, or a receive timeout had been set and the timeout expired
+before data was received.
+POSIX.1 allows either error to be returned for this case,
+and does not require these constants to have the same value,
+so a portable application should check for both possibilities.
+.TP
+.B EBADF
+The argument
+.I sockfd
+is an invalid file descriptor.
+.TP
+.B ECONNREFUSED
+A remote host refused to allow the network connection (typically
+because it is not running the requested service).
+.TP
+.B EFAULT
+The receive buffer pointer(s) point outside the process's
+address space.
+.TP
+.B EINTR
+The receive was interrupted by delivery of a signal before
+any data was available; see
+.BR signal (7).
+.TP
+.B EINVAL
+Invalid argument passed.
+.\" e.g., msg_namelen < 0 for recvmsg() or addrlen < 0 for recvfrom()
+.TP
+.B ENOMEM
+Could not allocate memory for
+.BR recvmsg ().
+.TP
+.B ENOTCONN
+The socket is associated with a connection-oriented protocol
+and has not been connected (see
+.BR connect (2)
+and
+.BR accept (2)).
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.SH VERSIONS
+According to POSIX.1,
+.\" POSIX.1-2001, POSIX.1-2008
+the
+.I msg_controllen
+field of the
+.I msghdr
+structure should be typed as
+.IR socklen_t ,
+and the
+.I msg_iovlen
+field should be typed as
+.IR int ,
+but glibc currently types both as
+.IR size_t .
+.\" glibc bug for msg_controllen raised 12 Mar 2006
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=2448
+.\" The problem is an underlying kernel issue: the size of the
+.\" __kernel_size_t type used to type these fields varies
+.\" across architectures, but socklen_t is always 32 bits,
+.\" as (at least with GCC) is int.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001,
+4.4BSD (first appeared in 4.2BSD).
+.P
+POSIX.1 describes only the
+.BR MSG_OOB ,
+.BR MSG_PEEK ,
+and
+.B MSG_WAITALL
+flags.
+.SH NOTES
+If a zero-length datagram is pending,
+.BR read (2)
+and
+.BR recv ()
+with a
+.I flags
+argument of zero provide different behavior.
+In this circumstance,
+.BR read (2)
+has no effect (the datagram remains pending), while
+.BR recv ()
+consumes the pending datagram.
+.P
+See
+.BR recvmmsg (2)
+for information about a Linux-specific system call
+that can be used to receive multiple datagrams in a single call.
+.SH EXAMPLES
+An example of the use of
+.BR recvfrom ()
+is shown in
+.BR getaddrinfo (3).
+.SH SEE ALSO
+.BR fcntl (2),
+.BR getsockopt (2),
+.BR read (2),
+.BR recvmmsg (2),
+.BR select (2),
+.BR shutdown (2),
+.BR socket (2),
+.BR cmsg (3),
+.BR sockatmark (3),
+.BR ip (7),
+.BR ipv6 (7),
+.BR socket (7),
+.BR tcp (7),
+.BR udp (7),
+.BR unix (7)
diff --git a/man/man2/recvfrom.2 b/man/man2/recvfrom.2
new file mode 100644
index 000000000..13228c391
--- /dev/null
+++ b/man/man2/recvfrom.2
@@ -0,0 +1 @@
+.so man2/recv.2
diff --git a/man/man2/recvmmsg.2 b/man/man2/recvmmsg.2
new file mode 100644
index 000000000..bf3c9d4ca
--- /dev/null
+++ b/man/man2/recvmmsg.2
@@ -0,0 +1,276 @@
+.\" Copyright (C) 2011 by Andi Kleen <andi@firstfloor.org>
+.\" and Copyright (c) 2011 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Syscall added in following commit
+.\"	commit a2e2725541fad72416326798c2d7fa4dafb7d337
+.\"	Author: Arnaldo Carvalho de Melo <acme@redhat.com>
+.\"	Date:   Mon Oct 12 23:40:10 2009 -0700
+.\"
+.TH recvmmsg 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+recvmmsg \- receive multiple messages on a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <sys/socket.h>
+.P
+.BI "int recvmmsg(int " sockfd ", struct mmsghdr *" msgvec \
+", unsigned int " vlen ","
+.BI "             int " flags ", struct timespec *" timeout ");"
+.fi
+.SH DESCRIPTION
+The
+.BR recvmmsg ()
+system call is an extension of
+.BR recvmsg (2)
+that allows the caller to receive multiple messages from a socket
+using a single system call.
+(This has performance benefits for some applications.)
+A further extension over
+.BR recvmsg (2)
+is support for a timeout on the receive operation.
+.P
+The
+.I sockfd
+argument is the file descriptor of the socket to receive data from.
+.P
+The
+.I msgvec
+argument is a pointer to an array of
+.I mmsghdr
+structures.
+The size of this array is specified in
+.IR vlen .
+.P
+The
+.I mmsghdr
+structure is defined in
+.I <sys/socket.h>
+as:
+.P
+.in +4n
+.EX
+struct mmsghdr {
+    struct msghdr msg_hdr;  /* Message header */
+    unsigned int  msg_len;  /* Number of received bytes for header */
+};
+.EE
+.in
+.P
+The
+.I msg_hdr
+field is a
+.I msghdr
+structure, as described in
+.BR recvmsg (2).
+The
+.I msg_len
+field is the number of bytes returned for the message in the entry.
+This field has the same value as the return value of a single
+.BR recvmsg (2)
+on the header.
+.P
+The
+.I flags
+argument contains flags ORed together.
+The flags are the same as documented for
+.BR recvmsg (2),
+with the following addition:
+.TP
+.BR MSG_WAITFORONE " (since Linux 2.6.34)"
+Turns on
+.B MSG_DONTWAIT
+after the first message has been received.
+.P
+The
+.I timeout
+argument points to a
+.I struct timespec
+(see
+.BR clock_gettime (2))
+defining a timeout (seconds plus nanoseconds) for the receive operation
+.RI ( "but see BUGS!" ).
+(This interval will be rounded up to the system clock granularity,
+and kernel scheduling delays mean that the blocking interval
+may overrun by a small amount.)
+If
+.I timeout
+is NULL, then the operation blocks indefinitely.
+.P
+A blocking
+.BR recvmmsg ()
+call blocks until
+.I vlen
+messages have been received
+or until the timeout expires.
+A nonblocking call reads as many messages as are available
+(up to the limit specified by
+.IR vlen )
+and returns immediately.
+.P
+On return from
+.BR recvmmsg (),
+successive elements of
+.I msgvec
+are updated to contain information about each received message:
+.I msg_len
+contains the size of the received message;
+the subfields of
+.I msg_hdr
+are updated as described in
+.BR recvmsg (2).
+The return value of the call indicates the number of elements of
+.I msgvec
+that have been updated.
+.SH RETURN VALUE
+On success,
+.BR recvmmsg ()
+returns the number of messages received in
+.IR msgvec ;
+on error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Errors are as for
+.BR recvmsg (2).
+In addition, the following error can occur:
+.TP
+.B EINVAL
+.I timeout
+is invalid.
+.P
+See also BUGS.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.33,
+glibc 2.12.
+.SH BUGS
+The
+.I timeout
+argument does not work as intended.
+.\" FIXME . https://bugzilla.kernel.org/show_bug.cgi?id=75371
+.\" http://thread.gmane.org/gmane.linux.man/5677
+The timeout is checked only after the receipt of each datagram,
+so that if up to
+.I vlen\-1
+datagrams are received before the timeout expires,
+but then no further datagrams are received, the call will block forever.
+.P
+If an error occurs after at least one message has been received,
+the call succeeds, and returns the number of messages received.
+The error code is expected to be returned on a subsequent call to
+.BR recvmmsg ().
+In the current implementation, however, the error code can be overwritten
+in the meantime by an unrelated network event on a socket,
+for example an incoming ICMP packet.
+.SH EXAMPLES
+The following program uses
+.BR recvmmsg ()
+to receive multiple messages on a socket and stores
+them in multiple buffers.
+The call returns if all buffers are filled or if the
+timeout specified has expired.
+.P
+The following snippet periodically generates UDP datagrams
+containing a random number:
+.P
+.in +4n
+.EX
+.RB "$" " while true; do echo $RANDOM > /dev/udp/127.0.0.1/1234;"
+.B      "      sleep 0.25; done"
+.EE
+.in
+.P
+These datagrams are read by the example application, which
+can give the following output:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+5 messages received
+1 11782
+2 11345
+3 304
+4 13514
+5 28421
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (recvmmsg.c)
+.EX
+#define _GNU_SOURCE
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <time.h>
+\&
+int
+main(void)
+{
+#define VLEN 10
+#define BUFSIZE 200
+#define TIMEOUT 1
+    int                 sockfd, retval;
+    char                bufs[VLEN][BUFSIZE+1];
+    struct iovec        iovecs[VLEN];
+    struct mmsghdr      msgs[VLEN];
+    struct timespec     timeout;
+    struct sockaddr_in  addr;
+\&
+    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (sockfd == \-1) {
+        perror("socket()");
+        exit(EXIT_FAILURE);
+    }
+\&
+    addr.sin_family = AF_INET;
+    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+    addr.sin_port = htons(1234);
+    if (bind(sockfd, (struct sockaddr *) &addr, sizeof(addr)) == \-1) {
+        perror("bind()");
+        exit(EXIT_FAILURE);
+    }
+\&
+    memset(msgs, 0, sizeof(msgs));
+    for (size_t i = 0; i < VLEN; i++) {
+        iovecs[i].iov_base         = bufs[i];
+        iovecs[i].iov_len          = BUFSIZE;
+        msgs[i].msg_hdr.msg_iov    = &iovecs[i];
+        msgs[i].msg_hdr.msg_iovlen = 1;
+    }
+\&
+    timeout.tv_sec = TIMEOUT;
+    timeout.tv_nsec = 0;
+\&
+    retval = recvmmsg(sockfd, msgs, VLEN, 0, &timeout);
+    if (retval == \-1) {
+        perror("recvmmsg()");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("%d messages received\en", retval);
+    for (size_t i = 0; i < retval; i++) {
+        bufs[i][msgs[i].msg_len] = 0;
+        printf("%zu %s", i+1, bufs[i]);
+    }
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR recvmsg (2),
+.BR sendmmsg (2),
+.BR sendmsg (2),
+.BR socket (2),
+.BR socket (7)
diff --git a/man/man2/recvmsg.2 b/man/man2/recvmsg.2
new file mode 100644
index 000000000..13228c391
--- /dev/null
+++ b/man/man2/recvmsg.2
@@ -0,0 +1 @@
+.so man2/recv.2
diff --git a/man/man2/remap_file_pages.2 b/man/man2/remap_file_pages.2
new file mode 100644
index 000000000..0c87352c0
--- /dev/null
+++ b/man/man2/remap_file_pages.2
@@ -0,0 +1,170 @@
+.\" Copyright (C) 2003, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2003-12-10 Initial creation, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2004-10-28 aeb, corrected prototype, prot must be 0
+.\"
+.TH remap_file_pages 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+remap_file_pages \- create a nonlinear file mapping
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <sys/mman.h>
+.P
+.BI "[[deprecated]] int remap_file_pages(void " addr [. size "], size_t " size ,
+.BI "                                    int " prot ", size_t " pgoff ", \
+int " flags );
+.fi
+.SH DESCRIPTION
+.BR Note :
+.\" commit 33041a0d76d3c3e0aff28ac95a2ffdedf1282dbc
+.\" http://lwn.net/Articles/597632/
+this system call was marked as deprecated starting with Linux 3.16.
+In Linux 4.0, the implementation was replaced
+.\" commit c8d78c1823f46519473949d33f0d1d33fe21ea16
+by a slower in-kernel emulation.
+Those few applications that use this system call should
+consider migrating to alternatives.
+This change was made because the kernel code for this system call was complex,
+and it is believed to be little used or perhaps even completely unused.
+While it had some use cases in database applications on 32-bit systems,
+those use cases don't exist on 64-bit systems.
+.P
+The
+.BR remap_file_pages ()
+system call is used to create a nonlinear mapping, that is, a mapping
+in which the pages of the file are mapped into a nonsequential order
+in memory.
+The advantage of using
+.BR remap_file_pages ()
+over using repeated calls to
+.BR mmap (2)
+is that the former approach does not require the kernel to create
+additional VMA (Virtual Memory Area) data structures.
+.P
+To create a nonlinear mapping we perform the following steps:
+.TP 3
+1.
+Use
+.BR mmap (2)
+to create a mapping (which is initially linear).
+This mapping must be created with the
+.B MAP_SHARED
+flag.
+.TP
+2.
+Use one or more calls to
+.BR remap_file_pages ()
+to rearrange the correspondence between the pages of the mapping
+and the pages of the file.
+It is possible to map the same page of a file
+into multiple locations within the mapped region.
+.P
+The
+.I pgoff
+and
+.I size
+arguments specify the region of the file that is to be relocated
+within the mapping:
+.I pgoff
+is a file offset in units of the system page size;
+.I size
+is the length of the region in bytes.
+.P
+The
+.I addr
+argument serves two purposes.
+First, it identifies the mapping whose pages we want to rearrange.
+Thus,
+.I addr
+must be an address that falls within
+a region previously mapped by a call to
+.BR mmap (2).
+Second,
+.I addr
+specifies the address at which the file pages
+identified by
+.I pgoff
+and
+.I size
+will be placed.
+.P
+The values specified in
+.I addr
+and
+.I size
+should be multiples of the system page size.
+If they are not, then the kernel rounds
+.I both
+values
+.I down
+to the nearest multiple of the page size.
+.\" This rounding is weird, and not consistent with the treatment of
+.\" the analogous arguments for munmap()/mprotect() and for mlock().
+.\" MTK, 14 Sep 2005
+.P
+The
+.I prot
+argument must be specified as 0.
+.P
+The
+.I flags
+argument has the same meaning as for
+.BR mmap (2),
+but all flags other than
+.B MAP_NONBLOCK
+are ignored.
+.SH RETURN VALUE
+On success,
+.BR remap_file_pages ()
+returns 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I addr
+does not refer to a valid mapping
+created with the
+.B MAP_SHARED
+flag.
+.TP
+.B EINVAL
+.IR addr ,
+.IR size ,
+.IR prot ,
+or
+.I pgoff
+is invalid.
+.\" And possibly others from vma->vm_ops->populate()
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.46,
+glibc 2.3.3.
+.SH NOTES
+Since Linux 2.6.23,
+.\" commit 3ee6dafc677a68e461a7ddafc94a580ebab80735
+.BR remap_file_pages ()
+creates non-linear mappings only
+on in-memory filesystems such as
+.BR tmpfs (5),
+hugetlbfs or ramfs.
+On filesystems with a backing store,
+.BR remap_file_pages ()
+is not much more efficient than using
+.BR mmap (2)
+to adjust which parts of the file are mapped to which addresses.
+.SH SEE ALSO
+.BR getpagesize (2),
+.BR mmap (2),
+.BR mmap2 (2),
+.BR mprotect (2),
+.BR mremap (2),
+.BR msync (2)
diff --git a/man/man2/removexattr.2 b/man/man2/removexattr.2
new file mode 100644
index 000000000..1d3a731e4
--- /dev/null
+++ b/man/man2/removexattr.2
@@ -0,0 +1,100 @@
+.\" Copyright (C) Andreas Gruenbacher, February 2001
+.\" Copyright (C) Silicon Graphics Inc, September 2001
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH removexattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+removexattr, lremovexattr, fremovexattr \- remove an extended attribute
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/xattr.h>
+.P
+.BI "int removexattr(const char *" path ", const char *" name );
+.BI "int lremovexattr(const char *" path ", const char *" name );
+.BI "int fremovexattr(int " fd ", const char *" name );
+.fi
+.SH DESCRIPTION
+Extended attributes are
+.IR name : value
+pairs associated with inodes (files, directories, symbolic links, etc.).
+They are extensions to the normal attributes which are associated
+with all inodes in the system (i.e., the
+.BR stat (2)
+data).
+A complete overview of extended attributes concepts can be found in
+.BR xattr (7).
+.P
+.BR removexattr ()
+removes the extended attribute identified by
+.I name
+and associated with the given
+.I path
+in the filesystem.
+.P
+.BR lremovexattr ()
+is identical to
+.BR removexattr (),
+except in the case of a symbolic link, where the extended attribute is
+removed from the link itself, not the file that it refers to.
+.P
+.BR fremovexattr ()
+is identical to
+.BR removexattr (),
+only the extended attribute is removed from the open file referred to by
+.I fd
+(as returned by
+.BR open (2))
+in place of
+.IR path .
+.P
+An extended attribute name is a null-terminated string.
+The
+.I name
+includes a namespace prefix; there may be several, disjoint
+namespaces associated with an individual inode.
+.SH RETURN VALUE
+On success, zero is returned.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENODATA
+The named attribute does not exist.
+.\" .RB ( ENOATTR
+.\" is defined to be a synonym for
+.\" .BR ENODATA
+.\" in
+.\" .IR <attr/attributes.h> .)
+.TP
+.B ENOTSUP
+Extended attributes are not supported by the filesystem, or are disabled.
+.P
+In addition, the errors documented in
+.BR stat (2)
+can also occur.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.4,
+glibc 2.3.
+.\" .SH AUTHORS
+.\" Andreas Gruenbacher,
+.\" .RI < a.gruenbacher@computer.org >
+.\" and the SGI XFS development team,
+.\" .RI < linux-xfs@oss.sgi.com >.
+.\" Please send any bug reports or comments to these addresses.
+.SH SEE ALSO
+.BR getfattr (1),
+.BR setfattr (1),
+.BR getxattr (2),
+.BR listxattr (2),
+.BR open (2),
+.BR setxattr (2),
+.BR stat (2),
+.BR symlink (7),
+.BR xattr (7)
diff --git a/man/man2/rename.2 b/man/man2/rename.2
new file mode 100644
index 000000000..617d8c29a
--- /dev/null
+++ b/man/man2/rename.2
@@ -0,0 +1,549 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt;
+.\"             and Copyright (C) 1993,1995 Ian Jackson
+.\"		and Copyright (C) 2006, 2014 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 00:35:52 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Thu Jun  4 12:21:13 1998 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Thu Mar  3 09:49:35 2005 by Michael Haardt <michael@moria.de>
+.\" 2007-03-25, mtk, added various text to DESCRIPTION.
+.\"
+.TH rename 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rename, renameat, renameat2 \- change the name or location of a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int rename(const char *" oldpath ", const char *" newpath );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of " AT_* " constants */"
+.B #include <stdio.h>
+.P
+.BI "int renameat(int " olddirfd ", const char *" oldpath ,
+.BI "             int " newdirfd ", const char *" newpath );
+.BI "int renameat2(int " olddirfd ", const char *" oldpath ,
+.BI "             int " newdirfd ", const char *" newpath \
+", unsigned int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.nf
+.BR renameat ():
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.P
+.BR renameat2 ():
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.BR rename ()
+renames a file, moving it between directories if required.
+Any other hard links to the file (as created using
+.BR link (2))
+are unaffected.
+Open file descriptors for
+.I oldpath
+are also unaffected.
+.P
+Various restrictions determine whether or not the rename operation succeeds:
+see ERRORS below.
+.P
+If
+.I newpath
+already exists, it will be atomically replaced, so that there is
+no point at which another process attempting to access
+.I newpath
+will find it missing.
+However, there will probably be a window in which both
+.I oldpath
+and
+.I newpath
+refer to the file being renamed.
+.P
+If
+.I oldpath
+and
+.I newpath
+are existing hard links referring to the same file, then
+.BR rename ()
+does nothing, and returns a success status.
+.P
+If
+.I newpath
+exists but the operation fails for some reason,
+.BR rename ()
+guarantees to leave an instance of
+.I newpath
+in place.
+.P
+.I oldpath
+can specify a directory.
+In this case,
+.I newpath
+must either not exist, or it must specify an empty directory.
+.P
+If
+.I oldpath
+refers to a symbolic link, the link is renamed; if
+.I newpath
+refers to a symbolic link, the link will be overwritten.
+.SS renameat()
+The
+.BR renameat ()
+system call operates in exactly the same way as
+.BR rename (),
+except for the differences described here.
+.P
+If the pathname given in
+.I oldpath
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I olddirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR rename ()
+for a relative pathname).
+.P
+If
+.I oldpath
+is relative and
+.I olddirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I oldpath
+is interpreted relative to the current working
+directory of the calling process (like
+.BR rename ()).
+.P
+If
+.I oldpath
+is absolute, then
+.I olddirfd
+is ignored.
+.P
+The interpretation of
+.I newpath
+is as for
+.IR oldpath ,
+except that a relative pathname is interpreted relative
+to the directory referred to by the file descriptor
+.IR newdirfd .
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR renameat ().
+.SS renameat2()
+.BR renameat2 ()
+has an additional
+.I flags
+argument.
+A
+.BR renameat2 ()
+call with a zero
+.I flags
+argument is equivalent to
+.BR renameat ().
+.P
+The
+.I flags
+argument is a bit mask consisting of zero or more of the following flags:
+.TP
+.B RENAME_EXCHANGE
+Atomically exchange
+.I oldpath
+and
+.IR newpath .
+Both pathnames must exist
+but may be of different types (e.g., one could be a non-empty directory
+and the other a symbolic link).
+.TP
+.B RENAME_NOREPLACE
+Don't overwrite
+.I newpath
+of the rename.
+Return an error if
+.I newpath
+already exists.
+.IP
+.B RENAME_NOREPLACE
+can't be employed together with
+.BR RENAME_EXCHANGE .
+.IP
+.B RENAME_NOREPLACE
+requires support from the underlying filesystem.
+Support for various filesystems was added as follows:
+.RS
+.IP \[bu] 3
+ext4 (Linux 3.15);
+.\" ext4: commit 0a7c3937a1f23f8cb5fc77ae01661e9968a51d0c
+.IP \[bu]
+btrfs, tmpfs, and cifs (Linux 3.17);
+.IP \[bu]
+xfs (Linux 4.0);
+.\" btrfs: commit 80ace85c915d0f41016f82917218997b72431258
+.\" tmpfs: commit 3b69ff51d087d265aa4af3a532fc4f20bf33e718
+.\" cifs: commit 7c33d5972ce382bcc506d16235f1e9b7d22cbef8
+.\"
+.\" gfs2 in Linux 4.2?
+.IP \[bu]
+Support for many other filesystems was added in Linux 4.9, including
+ext2, minix, reiserfs, jfs, vfat, and bpf.
+.\" Also affs, bfs, exofs, hfs, hfsplus, jffs2, logfs, msdos,
+.\" nilfs2, omfs, sysvfs, ubifs, udf, ufs
+.\" hugetlbfs, ramfs
+.\" local filesystems: commit f03b8ad8d38634d13e802165cc15917481b47835
+.\" libfs: commit e0e0be8a835520e2f7c89f214dfda570922a1b90
+.RE
+.TP
+.BR RENAME_WHITEOUT " (since Linux 3.18)"
+.\" commit 0d7a855526dd672e114aff2ac22b60fc6f155b08
+.\" commit 787fb6bc9682ec7c05fb5d9561b57100fbc1cc41
+This operation makes sense only for overlay/union
+filesystem implementations.
+.IP
+Specifying
+.B RENAME_WHITEOUT
+creates a "whiteout" object at the source of
+the rename at the same time as performing the rename.
+The whole operation is atomic,
+so that if the rename succeeds then the whiteout will also have been created.
+.IP
+A "whiteout" is an object that has special meaning in union/overlay
+filesystem constructs.
+In these constructs,
+multiple layers exist and only the top one is ever modified.
+A whiteout on an upper layer will effectively hide a
+matching file in the lower layer,
+making it appear as if the file didn't exist.
+.IP
+When a file that exists on the lower layer is renamed,
+the file is first copied up (if not already on the upper layer)
+and then renamed on the upper, read-write layer.
+At the same time, the source file needs to be "whiteouted"
+(so that the version of the source file in the lower layer
+is rendered invisible).
+The whole operation needs to be done atomically.
+.IP
+When not part of a union/overlay,
+the whiteout appears as a character device with a {0,0} device number.
+.\" https://www.freebsd.org/cgi/man.cgi?query=mount_unionfs&manpath=FreeBSD+11.0-RELEASE
+(Note that other union/overlay implementations may employ different methods
+for storing whiteout entries; specifically, BSD union mount employs
+a separate inode type,
+.BR DT_WHT ,
+which, while supported by some filesystems available in Linux,
+such as CODA and XFS, is ignored by the kernel's whiteout support code,
+as of Linux 4.19, at least.)
+.IP
+.B RENAME_WHITEOUT
+requires the same privileges as creating a device node (i.e., the
+.B CAP_MKNOD
+capability).
+.IP
+.B RENAME_WHITEOUT
+can't be employed together with
+.BR RENAME_EXCHANGE .
+.IP
+.B RENAME_WHITEOUT
+requires support from the underlying filesystem.
+Among the filesystems that support it are
+tmpfs (since Linux 3.18),
+.\" tmpfs: commit 46fdb794e3f52ef18b859ebc92f0a9d7db21c5df
+ext4 (since Linux 3.18),
+.\" ext4: commit cd808deced431b66b5fa4e5c193cb7ec0059eaff
+XFS (since Linux 4.1),
+.\" XFS: commit 7dcf5c3e4527cfa2807567b00387cf2ed5e07f00
+f2fs (since Linux 4.2),
+.\" f2fs: commit 7e01e7ad746bc8198a8b46163ddc73a1c7d22339
+btrfs (since Linux 4.7),
+.\" btrfs: commit cdd1fedf8261cd7a73c0596298902ff4f0f04492
+and ubifs (since Linux 4.9).
+.\" ubifs: commit 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Write permission is denied for the directory containing
+.I oldpath
+or
+.IR newpath ,
+or, search permission is denied for one of the directories
+in the path prefix of
+.I oldpath
+or
+.IR newpath ,
+or
+.I oldpath
+is a directory and does not allow write permission (needed to update
+the
+.I ..
+entry).
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBUSY
+The rename fails because
+.IR oldpath " or " newpath
+is a directory that is in use by some process (perhaps as
+current working directory, or as root directory, or because
+it was open for reading) or is in use by the system
+(for example as a mount point), while the system considers
+this an error.
+(Note that there is no requirement to return
+.B EBUSY
+in such
+cases\[em]there is nothing wrong with doing the rename anyway\[em]but
+it is allowed to return
+.B EBUSY
+if the system cannot otherwise
+handle such situations.)
+.TP
+.B EDQUOT
+The user's quota of disk blocks on the filesystem has been exhausted.
+.TP
+.B EFAULT
+.IR oldpath " or " newpath " points outside your accessible address space."
+.TP
+.B EINVAL
+The new pathname contained a path prefix of the old, or, more generally,
+an attempt was made to make a directory a subdirectory of itself.
+.TP
+.B EISDIR
+.I newpath
+is an existing directory, but
+.I oldpath
+is not a directory.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR oldpath " or " newpath .
+.TP
+.B EMLINK
+.I oldpath
+already has the maximum number of links to it, or
+it was a directory and the directory containing
+.I newpath
+has the maximum number of links.
+.TP
+.B ENAMETOOLONG
+.IR oldpath " or " newpath " was too long."
+.TP
+.B ENOENT
+The link named by
+.I oldpath
+does not exist;
+or, a directory component in
+.I newpath
+does not exist;
+or,
+.I oldpath
+or
+.I newpath
+is an empty string.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSPC
+The device containing the file has no room for the new directory
+entry.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.IR oldpath " or " newpath
+is not, in fact, a directory.
+Or,
+.I oldpath
+is a directory, and
+.I newpath
+exists but is not a directory.
+.TP
+.BR ENOTEMPTY " or " EEXIST
+.I newpath
+is a nonempty directory, that is, contains entries other than "." and "..".
+.TP
+.BR EPERM " or " EACCES
+The directory containing
+.I oldpath
+has the sticky bit
+.RB ( S_ISVTX )
+set and the process's effective user ID is neither
+the user ID of the file to be deleted nor that of the directory
+containing it, and the process is not privileged
+(Linux: does not have the
+.B CAP_FOWNER
+capability);
+or
+.I newpath
+is an existing file and the directory containing it has the sticky bit set
+and the process's effective user ID is neither the user ID of the file
+to be replaced nor that of the directory containing it,
+and the process is not privileged
+(Linux: does not have the
+.B CAP_FOWNER
+capability);
+or the filesystem containing
+.I oldpath
+does not support renaming of the type requested.
+.TP
+.B EROFS
+The file is on a read-only filesystem.
+.TP
+.B EXDEV
+.IR oldpath " and " newpath
+are not on the same mounted filesystem.
+(Linux permits a filesystem to be mounted at multiple points, but
+.BR rename ()
+does not work across different mount points,
+even if the same filesystem is mounted on both.)
+.P
+The following additional errors can occur for
+.BR renameat ()
+and
+.BR renameat2 ():
+.TP
+.B EBADF
+.I oldpath
+.RI ( newpath )
+is relative but
+.I olddirfd
+.RI ( newdirfd )
+is not a valid file descriptor.
+.TP
+.B ENOTDIR
+.I oldpath
+is relative and
+.I olddirfd
+is a file descriptor referring to a file other than a directory;
+or similar for
+.I newpath
+and
+.I newdirfd
+.P
+The following additional errors can occur for
+.BR renameat2 ():
+.TP
+.B EEXIST
+.I flags
+contains
+.B RENAME_NOREPLACE
+and
+.I newpath
+already exists.
+.TP
+.B EINVAL
+An invalid flag was specified in
+.IR flags .
+.TP
+.B EINVAL
+Both
+.B RENAME_NOREPLACE
+and
+.B RENAME_EXCHANGE
+were specified in
+.IR flags .
+.TP
+.B EINVAL
+Both
+.B RENAME_WHITEOUT
+and
+.B RENAME_EXCHANGE
+were specified in
+.IR flags .
+.TP
+.B EINVAL
+The filesystem does not support one of the flags in
+.IR flags .
+.TP
+.B ENOENT
+.I flags
+contains
+.B RENAME_EXCHANGE
+and
+.I newpath
+does not exist.
+.TP
+.B EPERM
+.B RENAME_WHITEOUT
+was specified in
+.IR flags ,
+but the caller does not have the
+.B CAP_MKNOD
+capability.
+.SH STANDARDS
+.TP
+.BR rename ()
+C11, POSIX.1-2008.
+.TP
+.BR renameat ()
+POSIX.1-2008.
+.TP
+.BR renameat2 ()
+Linux.
+.SH HISTORY
+.TP
+.BR rename ()
+4.3BSD, C89, POSIX.1-2001.
+.TP
+.BR renameat ()
+Linux 2.6.16,
+glibc 2.4.
+.TP
+.BR renameat2 ()
+Linux 3.15,
+glibc 2.28.
+.SS glibc notes
+On older kernels where
+.BR renameat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR rename ().
+When
+.I oldpath
+and
+.I newpath
+are relative pathnames,
+glibc constructs pathnames based on the symbolic links in
+.I /proc/self/fd
+that correspond to the
+.I olddirfd
+and
+.I newdirfd
+arguments.
+.SH BUGS
+On NFS filesystems, you can not assume that if the operation
+failed, the file was not renamed.
+If the server does the rename operation
+and then crashes, the retransmitted RPC which will be processed when the
+server is up again causes a failure.
+The application is expected to
+deal with this.
+See
+.BR link (2)
+for a similar problem.
+.SH SEE ALSO
+.BR mv (1),
+.BR rename (1),
+.BR chmod (2),
+.BR link (2),
+.BR symlink (2),
+.BR unlink (2),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/renameat.2 b/man/man2/renameat.2
new file mode 100644
index 000000000..9b74442c8
--- /dev/null
+++ b/man/man2/renameat.2
@@ -0,0 +1 @@
+.so man2/rename.2
diff --git a/man/man2/renameat2.2 b/man/man2/renameat2.2
new file mode 100644
index 000000000..9b74442c8
--- /dev/null
+++ b/man/man2/renameat2.2
@@ -0,0 +1 @@
+.so man2/rename.2
diff --git a/man/man2/request_key.2 b/man/man2/request_key.2
new file mode 100644
index 000000000..53c47e450
--- /dev/null
+++ b/man/man2/request_key.2
@@ -0,0 +1,562 @@
+.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+.\"     Written by David Howells (dhowells@redhat.com)
+.\" and Copyright (C) 2016 Michael Kerrisk <mtk.man-pages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH request_key 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+request_key \- request a key from the kernel's key management facility
+.SH LIBRARY
+Linux Key Management Utilities
+.RI ( libkeyutils ", " \-lkeyutils )
+.SH SYNOPSIS
+.nf
+.B #include <keyutils.h>
+.P
+.BI "key_serial_t request_key(const char *" type ", const char *" description ,
+.BI "                         const char *_Nullable " callout_info ,
+.BI "                         key_serial_t " dest_keyring );
+.fi
+.SH DESCRIPTION
+.BR request_key ()
+attempts to find a key of the given
+.I type
+with a description (name) that matches the specified
+.IR description .
+If such a key could not be found, then the key is optionally created.
+If the key is found or created,
+.BR request_key ()
+attaches it to the keyring whose ID is specified in
+.I dest_keyring
+and returns the key's serial number.
+.P
+.BR request_key ()
+first recursively searches for a matching key in all of the keyrings
+attached to the calling process.
+The keyrings are searched in the order: thread-specific keyring,
+process-specific keyring, and then session keyring.
+.P
+If
+.BR request_key ()
+is called from a program invoked by
+.BR request_key ()
+on behalf of some other process to generate a key, then the keyrings of that
+other process will be searched next,
+using that other process's user ID, group ID,
+supplementary group IDs, and security context to determine access.
+.\" David Howells: we can then have an arbitrarily long sequence
+.\" of "recursive" request-key upcalls. There is no limit, other
+.\" than number of PIDs, etc.
+.P
+The search of the keyring tree is breadth-first:
+the keys in each keyring searched are checked for a match before any child
+keyrings are recursed into.
+Only keys for which the caller has
+.I search
+permission be found, and only keyrings for which the caller has
+.I search
+permission may be searched.
+.P
+If the key is not found and
+.I callout
+is NULL, then the call fails with the error
+.BR ENOKEY .
+.P
+If the key is not found and
+.I callout
+is not NULL, then the kernel attempts to invoke a user-space
+program to instantiate the key.
+The details are given below.
+.P
+The
+.I dest_keyring
+serial number may be that of a valid keyring for which the caller has
+.I write
+permission, or it may be one of the following special keyring IDs:
+.TP
+.B KEY_SPEC_THREAD_KEYRING
+This specifies the caller's thread-specific keyring (see
+.BR thread\-keyring (7)).
+.TP
+.B KEY_SPEC_PROCESS_KEYRING
+This specifies the caller's process-specific keyring (see
+.BR process\-keyring (7)).
+.TP
+.B KEY_SPEC_SESSION_KEYRING
+This specifies the caller's session-specific keyring (see
+.BR session\-keyring (7)).
+.TP
+.B KEY_SPEC_USER_KEYRING
+This specifies the caller's UID-specific keyring (see
+.BR user\-keyring (7)).
+.TP
+.B KEY_SPEC_USER_SESSION_KEYRING
+This specifies the caller's UID-session keyring (see
+.BR user\-session\-keyring (7)).
+.P
+When the
+.I dest_keyring
+is specified as 0
+and no key construction has been performed,
+then no additional linking is done.
+.P
+Otherwise, if
+.I dest_keyring
+is 0 and a new key is constructed, the new key will be linked
+to the "default" keyring.
+More precisely, when the kernel tries to determine to which keyring the
+newly constructed key should be linked,
+it tries the following keyrings,
+beginning with the keyring set via the
+.BR keyctl (2)
+.B KEYCTL_SET_REQKEY_KEYRING
+operation and continuing in the order shown below
+until it finds the first keyring that exists:
+.IP \[bu] 3
+.\" 8bbf4976b59fc9fc2861e79cab7beb3f6d647640
+The requestor keyring
+.RB ( KEY_REQKEY_DEFL_REQUESTOR_KEYRING ,
+since Linux 2.6.29).
+.\" FIXME
+.\" Actually, is the preceding point correct?
+.\" If I understand correctly, we'll only get here if
+.\" 'dest_keyring' is zero, in which case KEY_REQKEY_DEFL_REQUESTOR_KEYRING
+.\" won't refer to a keyring. Have I misunderstood?
+.IP \[bu]
+The thread-specific keyring
+.RB ( KEY_REQKEY_DEFL_THREAD_KEYRING ;
+see
+.BR thread\-keyring (7)).
+.IP \[bu]
+The process-specific keyring
+.RB ( KEY_REQKEY_DEFL_PROCESS_KEYRING ;
+see
+.BR process\-keyring (7)).
+.IP \[bu]
+The session-specific keyring
+.RB ( KEY_REQKEY_DEFL_SESSION_KEYRING ;
+see
+.BR session\-keyring (7)).
+.IP \[bu]
+The session keyring for the process's user ID
+.RB ( KEY_REQKEY_DEFL_USER_SESSION_KEYRING ;
+see
+.BR user\-session\-keyring (7)).
+This keyring is expected to always exist.
+.IP \[bu]
+The UID-specific keyring
+.RB ( KEY_REQKEY_DEFL_USER_KEYRING ;
+see
+.BR user\-keyring (7)).
+This keyring is also expected to always exist.
+.\" mtk: Are there circumstances where the user sessions and UID-specific
+.\" keyrings do not exist?
+.\"
+.\" David Howells:
+.\"     The uid keyrings don't exist until someone tries to access them -
+.\"     at which point they're both created.  When you log in, pam_keyinit
+.\"     creates a link to your user keyring in the session keyring it just
+.\"     created, thereby creating the user and user-session keyrings.
+.\"
+.\" and David elaborated that "access" means:
+.\"
+.\"     It means lookup_user_key() was passed KEY_LOOKUP_CREATE.  So:
+.\"
+.\"         add_key() - destination keyring
+.\"         request_key() - destination keyring
+.\"         KEYCTL_GET_KEYRING_ID - if create arg is true
+.\"         KEYCTL_CLEAR
+.\"         KEYCTL_LINK - both args
+.\"         KEYCTL_SEARCH - destination keyring
+.\"         KEYCTL_CHOWN
+.\"         KEYCTL_SETPERM
+.\"         KEYCTL_SET_TIMEOUT
+.\"         KEYCTL_INSTANTIATE - destination keyring
+.\"         KEYCTL_INSTANTIATE_IOV - destination keyring
+.\"         KEYCTL_NEGATE - destination keyring
+.\"         KEYCTL_REJECT - destination keyring
+.\"         KEYCTL_GET_PERSISTENT - destination keyring
+.\"
+.\"     will all create a keyring under some circumstances.  Whereas the rest,
+.\"     such as KEYCTL_GET_SECURITY, KEYCTL_READ and KEYCTL_REVOKE, won't.
+.P
+If the
+.BR keyctl (2)
+.B KEYCTL_SET_REQKEY_KEYRING
+operation specifies
+.B KEY_REQKEY_DEFL_DEFAULT
+(or no
+.B KEYCTL_SET_REQKEY_KEYRING
+operation is performed),
+then the kernel looks for a keyring
+starting from the beginning of the list.
+.\"
+.SS Requesting user-space instantiation of a key
+If the kernel cannot find a key matching
+.I type
+and
+.IR description ,
+and
+.I callout
+is not NULL, then the kernel attempts to invoke a user-space
+program to instantiate a key with the given
+.I type
+and
+.IR description .
+In this case, the following steps are performed:
+.IP (1) 5
+The kernel creates an uninstantiated key, U, with the requested
+.I type
+and
+.IR description .
+.IP (2)
+The kernel creates an authorization key, V,
+.\" struct request_key_auth, defined in security/keys/internal.h
+that refers to the key U and records the facts that the caller of
+.BR request_key ()
+is:
+.RS
+.IP (2.1) 7
+the context in which the key U should be instantiated and secured, and
+.IP (2.2)
+the context from which associated key requests may be satisfied.
+.RE
+.IP
+The authorization key is constructed as follows:
+.RS
+.IP \[bu] 3
+The key type is
+.IR \[dq].request_key_auth\[dq] .
+.IP \[bu]
+The key's UID and GID are the same as the corresponding filesystem IDs
+of the requesting process.
+.IP \[bu]
+The key grants
+.IR view ,
+.IR read ,
+and
+.I search
+permissions to the key possessor as well as
+.I view
+permission for the key user.
+.IP \[bu]
+The description (name) of the key is the hexadecimal
+string representing the ID of the key that is to be instantiated
+in the requesting program.
+.IP \[bu]
+The payload of the key is taken from the data specified in
+.IR callout_info .
+.IP \[bu]
+Internally, the kernel also records the PID of the process that called
+.BR request_key ().
+.RE
+.IP (3)
+The kernel creates a process that executes a user-space service such as
+.BR request\-key (8)
+with a new session keyring that contains a link to the authorization key, V.
+.\" The request\-key(8) program can be invoked in circumstances *other* than
+.\" when triggered by request_key(2). For example, upcalls from places such
+.\" as the DNS resolver.
+.IP
+This program is supplied with the following command-line arguments:
+.RS
+.IP [0] 5
+The string
+.IR \[dq]/sbin/request\-key\[dq] .
+.IP [1]
+The string
+.I \[dq]create\[dq]
+(indicating that a key is to be created).
+.IP [2]
+The ID of the key that is to be instantiated.
+.IP [3]
+The filesystem UID of the caller of
+.BR request_key ().
+.IP [4]
+The filesystem GID of the caller of
+.BR request_key ().
+.IP [5]
+The ID of the thread keyring of the caller of
+.BR request_key ().
+This may be zero if that keyring hasn't been created.
+.IP [6]
+The ID of the process keyring of the caller of
+.BR request_key ().
+This may be zero if that keyring hasn't been created.
+.IP [7]
+The ID of the session keyring of the caller of
+.BR request_key ().
+.RE
+.IP
+.IR Note :
+each of the command-line arguments that is a key ID is encoded in
+.I decimal
+(unlike the key IDs shown in
+.IR /proc/keys ,
+which are shown as hexadecimal values).
+.IP (4)
+The program spawned in the previous step:
+.RS
+.IP \[bu] 3
+Assumes the authority to instantiate the key U using the
+.BR keyctl (2)
+.B KEYCTL_ASSUME_AUTHORITY
+operation (typically via the
+.BR keyctl_assume_authority (3)
+function).
+.IP \[bu]
+Obtains the callout data from the payload of the authorization key V
+(using the
+.BR keyctl (2)
+.B KEYCTL_READ
+operation (or, more commonly, the
+.BR keyctl_read (3)
+function) with a key ID value of
+.BR KEY_SPEC_REQKEY_AUTH_KEY ).
+.IP \[bu]
+Instantiates the key
+(or execs another program that performs that task),
+specifying the payload and destination keyring.
+(The destination keyring that the requestor specified when calling
+.BR request_key ()
+can be accessed using the special key ID
+.BR KEY_SPEC_REQUESTOR_KEYRING .)
+.\" Should an instantiating program be using KEY_SPEC_REQUESTOR_KEYRING?
+.\" I couldn't find a use in the keyutils git repo.
+.\" According to David Howells:
+.\" * This feature is provided, but not used at the moment.
+.\" * A key added to that ring is then owned by the requester
+Instantiation is performed using the
+.BR keyctl (2)
+.B KEYCTL_INSTANTIATE
+operation (or, more commonly, the
+.BR keyctl_instantiate (3)
+function).
+At this point, the
+.BR request_key ()
+call completes, and the requesting program can continue execution.
+.RE
+.P
+If these steps are unsuccessful, then an
+.B ENOKEY
+error will be returned to the caller of
+.BR request_key ()
+and a temporary, negatively instantiated key will be installed
+in the keyring specified by
+.IR dest_keyring .
+This will expire after a few seconds, but will cause subsequent calls to
+.BR request_key ()
+to fail until it does.
+The purpose of this negatively instantiated key is to prevent
+(possibly different) processes making repeated requests
+(that require expensive
+.BR request\-key (8)
+upcalls) for a key that can't (at the moment) be positively instantiated.
+.P
+Once the key has been instantiated, the authorization key
+.RB ( KEY_SPEC_REQKEY_AUTH_KEY )
+is revoked, and the destination keyring
+.RB ( KEY_SPEC_REQUESTOR_KEYRING )
+is no longer accessible from the
+.BR request\-key (8)
+program.
+.P
+If a key is created, then\[em]regardless of whether it is a valid key or
+a negatively instantiated key\[em]it will displace any other key with
+the same type and description from the keyring specified in
+.IR dest_keyring .
+.SH RETURN VALUE
+On success,
+.BR request_key ()
+returns the serial number of the key it found or caused to be created.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The keyring wasn't available for modification by the user.
+.TP
+.B EDQUOT
+The key quota for this user would be exceeded by creating this key or linking
+it to the keyring.
+.TP
+.B EFAULT
+One of
+.IR type ,
+.IR description ,
+or
+.I callout_info
+points outside the process's accessible address space.
+.TP
+.B EINTR
+The request was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EINVAL
+The size of the string (including the terminating null byte) specified in
+.I type
+or
+.I description
+exceeded the limit (32 bytes and 4096 bytes respectively).
+.TP
+.B EINVAL
+The size of the string (including the terminating null byte) specified in
+.I callout_info
+exceeded the system page size.
+.TP
+.B EKEYEXPIRED
+An expired key was found, but no replacement could be obtained.
+.TP
+.B EKEYREJECTED
+The attempt to generate a new key was rejected.
+.TP
+.B EKEYREVOKED
+A revoked key was found, but no replacement could be obtained.
+.TP
+.B ENOKEY
+No matching key was found.
+.TP
+.B ENOMEM
+Insufficient memory to create a key.
+.TP
+.B EPERM
+The
+.I type
+argument started with a period (\[aq].\[aq]).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.10.
+.P
+The ability to instantiate keys upon request was added
+.\" commit 3e30148c3d524a9c1c63ca28261bc24c457eb07a
+in Linux 2.6.13.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR request_key ().
+The
+.IR type ,
+.IR description ,
+and
+.I callout_info
+arguments for the system call are taken from the values
+supplied in the command-line arguments.
+The call specifies the session keyring as the target keyring.
+.P
+In order to demonstrate this program,
+we first create a suitable entry in the file
+.IR /etc/request\-key.conf .
+.P
+.in +4n
+.EX
+$ sudo sh
+# \fBecho \[aq]create user mtk:* *   /bin/keyctl instantiate %k %c %S\[aq] \e\fP
+          \fB> /etc/request\-key.conf\fP
+# \fBexit\fP
+.EE
+.in
+.P
+This entry specifies that when a new "user" key with the prefix
+"mtk:" must be instantiated, that task should be performed via the
+.BR keyctl (1)
+command's
+.B instantiate
+operation.
+The arguments supplied to the
+.B instantiate
+operation are:
+the ID of the uninstantiated key
+.RI ( %k );
+the callout data supplied to the
+.BR request_key ()
+call
+.RI ( %c );
+and the session keyring
+.RI ( %S )
+of the requestor (i.e., the caller of
+.BR request_key ()).
+See
+.BR request\-key.conf (5)
+for details of these
+.I %
+specifiers.
+.P
+Then we run the program and check the contents of
+.I /proc/keys
+to verify that the requested key has been instantiated:
+.P
+.in +4n
+.EX
+$ \fB./t_request_key user mtk:key1 "Payload data"\fP
+$ \fBgrep \[aq]2dddaf50\[aq] /proc/keys\fP
+2dddaf50 I\-\-Q\-\-\-  1 perm 3f010000  1000  1000 user  mtk:key1: 12
+.EE
+.in
+.P
+For another example of the use of this program, see
+.BR keyctl (2).
+.SS Program source
+\&
+.\" SRC BEGIN (t_request_key.c)
+.EX
+/* t_request_key.c */
+\&
+#include <keyutils.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    key_serial_t key;
+\&
+    if (argc != 4) {
+        fprintf(stderr, "Usage: %s type description callout\-data\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    key = request_key(argv[1], argv[2], argv[3],
+                      KEY_SPEC_SESSION_KEYRING);
+    if (key == \-1) {
+        perror("request_key");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Key ID is %jx\en", (uintmax_t) key);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR add_key (2),
+.BR keyctl (2),
+.BR keyctl (3),
+.BR capabilities (7),
+.BR keyrings (7),
+.BR keyutils (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7),
+.BR user\-session\-keyring (7),
+.BR request\-key (8)
+.P
+The kernel source files
+.I Documentation/security/keys/core.rst
+and
+.I Documentation/keys/request\-key.rst
+(or, before Linux 4.13, in the files
+.\" commit b68101a1e8f0263dbc7b8375d2a7c57c6216fb76
+.I Documentation/security/keys.txt
+and
+.\" commit 3db38ed76890565772fcca3279cc8d454ea6176b
+.IR Documentation/security/keys\-request\-key.txt ).
diff --git a/man/man2/restart_syscall.2 b/man/man2/restart_syscall.2
new file mode 100644
index 000000000..c90bb3827
--- /dev/null
+++ b/man/man2/restart_syscall.2
@@ -0,0 +1,123 @@
+.\" Copyright (c) 2013 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" http://thread.gmane.org/gmane.linux.kernel/76552/focus=76803
+.\" From: Linus Torvalds <torvalds <at> transmeta.com>
+.\" Subject: Re: [PATCH] compatibility syscall layer (lets try again)
+.\" Newsgroups: gmane.linux.kernel
+.\" Date: 2002-12-05 02:51:12 GMT
+.\"
+.\" See also Section 11.3.3 of Understanding the Linux Kernel, 3rd edition
+.\"
+.TH restart_syscall 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+restart_syscall \- restart a system call after interruption by a stop signal
+.SH SYNOPSIS
+.nf
+.B long restart_syscall(void);
+.fi
+.P
+.IR Note :
+There is no glibc wrapper for this system call; see NOTES.
+.SH DESCRIPTION
+The
+.BR restart_syscall ()
+system call is used to restart certain system calls
+after a process that was stopped by a signal (e.g.,
+.B SIGSTOP
+or
+.BR SIGTSTP )
+is later resumed after receiving a
+.B SIGCONT
+signal.
+This system call is designed only for internal use by the kernel.
+.P
+.BR restart_syscall ()
+is used for restarting only those system calls that,
+when restarted, should adjust their time-related parameters\[em]namely
+.BR poll (2)
+(since Linux 2.6.24),
+.BR nanosleep (2)
+(since Linux 2.6),
+.BR clock_nanosleep (2)
+(since Linux 2.6),
+and
+.BR futex (2),
+when employed with the
+.B FUTEX_WAIT
+(since Linux 2.6.22)
+and
+.B FUTEX_WAIT_BITSET
+(since Linux 2.6.31)
+operations.
+.\" These system calls correspond to the special internal errno value
+.\" ERESTART_RESTARTBLOCK. Each of the system calls has a "restart"
+.\" helper function that is invoked by restart_syscall().
+.\" Notable (as at Linux 3.17) is that poll() has such a "restart"
+.\" function, but ppoll(), select(), and pselect() do not.
+.\" This means that the latter system calls do not take account of the
+.\" time spent in the stopped state when restarting.
+.BR restart_syscall ()
+restarts the interrupted system call with a
+time argument that is suitably adjusted to account for the
+time that has already elapsed (including the time where the process
+was stopped by a signal).
+Without the
+.BR restart_syscall ()
+mechanism, restarting these system calls would not correctly deduct the
+already elapsed time when the process continued execution.
+.SH RETURN VALUE
+The return value of
+.BR restart_syscall ()
+is the return value of whatever system call is being restarted.
+.SH ERRORS
+.I errno
+is set as per the errors for whatever system call is being restarted by
+.BR restart_syscall ().
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.
+.SH NOTES
+There is no glibc wrapper for this system call,
+because it is intended for use only by the kernel and
+should never be called by applications.
+.P
+The kernel uses
+.BR restart_syscall ()
+to ensure that when a system call is restarted
+after a process has been stopped by a signal and then resumed by
+.BR SIGCONT ,
+then the time that the process spent in the stopped state is counted
+against the timeout interval specified in the original system call.
+In the case of system calls that take a timeout argument and
+automatically restart after a stop signal plus
+.BR SIGCONT ,
+but which do not have the
+.BR restart_syscall ()
+mechanism built in, then, after the process resumes execution,
+the time that the process spent in the stop state is
+.I not
+counted against the timeout value.
+Notable examples of system calls that suffer this problem are
+.BR ppoll (2),
+.BR select (2),
+and
+.BR pselect (2).
+.P
+From user space, the operation of
+.BR restart_syscall ()
+is largely invisible:
+to the process that made the system call that is restarted,
+it appears as though that system call executed and
+returned in the usual fashion.
+.SH SEE ALSO
+.BR sigaction (2),
+.BR sigreturn (2),
+.BR signal (7)
+.\" FIXME . ppoll(2), select(2), and pselect(2)
+.\"     should probably get the restart_syscall() treatment:
+.\"     If a select() call is suspended by stop-sig+SIGCONT, the time
+.\"     spent suspended is *not* deducted when the select() is restarted.
+.\" FIXME . check whether recvmmsg() handles stop-sig+SIGCONT properly.
diff --git a/man/man2/rmdir.2 b/man/man2/rmdir.2
new file mode 100644
index 000000000..b3ab4904d
--- /dev/null
+++ b/man/man2/rmdir.2
@@ -0,0 +1,128 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH rmdir 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rmdir \- delete a directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int rmdir(const char *" pathname );
+.fi
+.SH DESCRIPTION
+.BR rmdir ()
+deletes a directory, which must be empty.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Write access to the directory containing
+.I pathname
+was not allowed, or one of the directories in the path prefix of
+.I pathname
+did not allow search permission.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBUSY
+.I pathname
+is currently in use by the system or some process that prevents its
+removal.
+On Linux, this means
+.I pathname
+is currently used as a mount point
+or is the root directory of the calling process.
+.TP
+.B EFAULT
+.IR pathname " points outside your accessible address space."
+.TP
+.B EINVAL
+.I pathname
+has
+.I .
+as last component.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B ENAMETOOLONG
+.IR pathname " was too long."
+.TP
+.B ENOENT
+A directory component in
+.I pathname
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+.IR pathname ,
+or a component used as a directory in
+.IR pathname ,
+is not, in fact, a directory.
+.TP
+.B ENOTEMPTY
+.I pathname
+contains entries other than
+.IR . " and " .. " ;"
+or,
+.I pathname
+has
+.I ..
+as its final component.
+POSIX.1 also allows
+.\" POSIX.1-2001, POSIX.1-2008
+.B EEXIST
+for this condition.
+.TP
+.B EPERM
+The directory containing
+.I pathname
+has the sticky bit
+.RB ( S_ISVTX )
+set and the process's effective user ID is neither the user ID
+of the file to be deleted nor that of the directory containing it,
+and the process is not privileged (Linux: does not have the
+.B CAP_FOWNER
+capability).
+.TP
+.B EPERM
+The filesystem containing
+.I pathname
+does not support the removal of directories.
+.TP
+.B EROFS
+.I pathname
+refers to a directory on a read-only filesystem.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH BUGS
+Infelicities in the protocol underlying NFS can cause the unexpected
+disappearance of directories which are still being used.
+.SH SEE ALSO
+.BR rm (1),
+.BR rmdir (1),
+.BR chdir (2),
+.BR chmod (2),
+.BR mkdir (2),
+.BR rename (2),
+.BR unlink (2),
+.BR unlinkat (2)
diff --git a/man/man2/rt_sigaction.2 b/man/man2/rt_sigaction.2
new file mode 100644
index 000000000..d642d26cf
--- /dev/null
+++ b/man/man2/rt_sigaction.2
@@ -0,0 +1 @@
+.so man2/sigaction.2
diff --git a/man/man2/rt_sigpending.2 b/man/man2/rt_sigpending.2
new file mode 100644
index 000000000..304adff9e
--- /dev/null
+++ b/man/man2/rt_sigpending.2
@@ -0,0 +1 @@
+.so man2/sigpending.2
diff --git a/man/man2/rt_sigprocmask.2 b/man/man2/rt_sigprocmask.2
new file mode 100644
index 000000000..5eab7ac86
--- /dev/null
+++ b/man/man2/rt_sigprocmask.2
@@ -0,0 +1 @@
+.so man2/sigprocmask.2
diff --git a/man/man2/rt_sigqueueinfo.2 b/man/man2/rt_sigqueueinfo.2
new file mode 100644
index 000000000..59d1d2cbe
--- /dev/null
+++ b/man/man2/rt_sigqueueinfo.2
@@ -0,0 +1,195 @@
+.\" Copyright (c) 2002, 2011 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH rt_sigqueueinfo 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rt_sigqueueinfo, rt_tgsigqueueinfo \- queue a signal and data
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/signal.h>" "     /* Definition of " SI_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_rt_sigqueueinfo, pid_t " tgid ,
+.BI "            int " sig ", siginfo_t *" info );
+.BI "int syscall(SYS_rt_tgsigqueueinfo, pid_t " tgid ", pid_t " tid ,
+.BI "            int " sig ", siginfo_t *" info );
+.fi
+.P
+.IR Note :
+There are no glibc wrappers for these system calls; see NOTES.
+.SH DESCRIPTION
+The
+.BR rt_sigqueueinfo ()
+and
+.BR rt_tgsigqueueinfo ()
+system calls are the low-level interfaces used to send a signal plus data
+to a process or thread.
+The receiver of the signal can obtain the accompanying data
+by establishing a signal handler with the
+.BR sigaction (2)
+.B SA_SIGINFO
+flag.
+.P
+These system calls are not intended for direct application use;
+they are provided to allow the implementation of
+.BR sigqueue (3)
+and
+.BR pthread_sigqueue (3).
+.P
+The
+.BR rt_sigqueueinfo ()
+system call sends the signal
+.I sig
+to the thread group with the ID
+.IR tgid .
+(The term "thread group" is synonymous with "process", and
+.I tid
+corresponds to the traditional UNIX process ID.)
+The signal will be delivered to an arbitrary member of the thread group
+(i.e., one of the threads that is not currently blocking the signal).
+.P
+The
+.I info
+argument specifies the data to accompany the signal.
+This argument is a pointer to a structure of type
+.IR siginfo_t ,
+described in
+.BR sigaction (2)
+(and defined by including
+.IR <sigaction.h> ).
+The caller should set the following fields in this structure:
+.TP
+.I si_code
+This should be one of the
+.B SI_*
+codes in the Linux kernel source file
+.IR include/asm\-generic/siginfo.h .
+If the signal is being sent to any process other than the caller itself,
+the following restrictions apply:
+.RS
+.IP \[bu] 3
+The code can't be a value greater than or equal to zero.
+In particular, it can't be
+.BR SI_USER ,
+which is used by the kernel to indicate a signal sent by
+.BR kill (2),
+and nor can it be
+.BR SI_KERNEL ,
+which is used to indicate a signal generated by the kernel.
+.IP \[bu]
+The code can't (since Linux 2.6.39) be
+.BR SI_TKILL ,
+which is used by the kernel to indicate a signal sent using
+.\" tkill(2) or
+.BR tgkill (2).
+.RE
+.TP
+.I si_pid
+This should be set to a process ID,
+typically the process ID of the sender.
+.TP
+.I si_uid
+This should be set to a user ID,
+typically the real user ID of the sender.
+.TP
+.I si_value
+This field contains the user data to accompany the signal.
+For more information, see the description of the last
+.RI ( "union sigval" )
+argument of
+.BR sigqueue (3).
+.P
+Internally, the kernel sets the
+.I si_signo
+field to the value specified in
+.IR sig ,
+so that the receiver of the signal can also obtain
+the signal number via that field.
+.P
+The
+.BR rt_tgsigqueueinfo ()
+system call is like
+.BR rt_sigqueueinfo (),
+but sends the signal and data to the single thread
+specified by the combination of
+.IR tgid ,
+a thread group ID,
+and
+.IR tid ,
+a thread in that thread group.
+.SH RETURN VALUE
+On success, these system calls return 0.
+On error, they return \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The limit of signals which may be queued has been reached.
+(See
+.BR signal (7)
+for further information.)
+.TP
+.B EINVAL
+.IR sig ,
+.IR tgid ,
+or
+.I tid
+was invalid.
+.TP
+.B EPERM
+The caller does not have permission to send the signal to the target.
+For the required permissions, see
+.BR kill (2).
+.TP
+.B EPERM
+.I tgid
+specifies a process other than the caller and
+.I info\->si_code
+is invalid.
+.TP
+.B ESRCH
+.BR rt_sigqueueinfo ():
+No thread group matching
+.I tgid
+was found.
+.P
+.BR rt_tgsigqueinfo ():
+No thread matching
+.I tgid
+and
+.I tid
+was found.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR rt_sigqueueinfo ()
+Linux 2.2.
+.TP
+.BR rt_tgsigqueueinfo ()
+Linux 2.6.31.
+.SH NOTES
+Since these system calls are not intended for application use,
+there are no glibc wrapper functions; use
+.BR syscall (2)
+in the unlikely case that you want to call them directly.
+.P
+As with
+.BR kill (2),
+the null signal (0) can be used to check if the specified process
+or thread exists.
+.SH SEE ALSO
+.BR kill (2),
+.BR pidfd_send_signal (2),
+.BR sigaction (2),
+.BR sigprocmask (2),
+.BR tgkill (2),
+.BR pthread_sigqueue (3),
+.BR sigqueue (3),
+.BR signal (7)
diff --git a/man/man2/rt_sigreturn.2 b/man/man2/rt_sigreturn.2
new file mode 100644
index 000000000..830b7b99f
--- /dev/null
+++ b/man/man2/rt_sigreturn.2
@@ -0,0 +1 @@
+.so man2/sigreturn.2
diff --git a/man/man2/rt_sigsuspend.2 b/man/man2/rt_sigsuspend.2
new file mode 100644
index 000000000..96d99c4c0
--- /dev/null
+++ b/man/man2/rt_sigsuspend.2
@@ -0,0 +1 @@
+.so man2/sigsuspend.2
diff --git a/man/man2/rt_sigtimedwait.2 b/man/man2/rt_sigtimedwait.2
new file mode 100644
index 000000000..ca098e5fc
--- /dev/null
+++ b/man/man2/rt_sigtimedwait.2
@@ -0,0 +1 @@
+.so man2/sigtimedwait.2
diff --git a/man/man2/rt_tgsigqueueinfo.2 b/man/man2/rt_tgsigqueueinfo.2
new file mode 100644
index 000000000..7b6cf6814
--- /dev/null
+++ b/man/man2/rt_tgsigqueueinfo.2
@@ -0,0 +1 @@
+.so man2/rt_sigqueueinfo.2
diff --git a/man/man2/s390_guarded_storage.2 b/man/man2/s390_guarded_storage.2
new file mode 100644
index 000000000..dd77e010c
--- /dev/null
+++ b/man/man2/s390_guarded_storage.2
@@ -0,0 +1,162 @@
+.\" Copyright (C) 2018 Eugene Syromyatnikov <evgsyr@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH s390_guarded_storage 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+s390_guarded_storage \- operations with z/Architecture guarded storage facility
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <asm/guarded_storage.h> " "/* Definition of " GS_* " constants */"
+.BR "#include <sys/syscall.h>         " \
+"/* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_s390_guarded_storage, int " command ,
+.BI "            struct gs_cb *" gs_cb );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR s390_guarded_storage (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR s390_guarded_storage ()
+system call enables the use of the Guarded Storage Facility
+(a z/Architecture-specific feature) for user-space processes.
+.P
+.\" The description is based on
+.\" http://www-05.ibm.com/de/linux-on-z-ws-us/agenda/pdfs/8_-_Linux_Whats_New_-_Stefan_Raspl.pdf
+.\" and "z/Architecture Principles of Operation" obtained from
+.\" http://publibfi.boulder.ibm.com/epubs/pdf/dz9zr011.pdf
+The guarded storage facility is a hardware feature that allows marking up to
+64 memory regions (as of z14) as guarded;
+reading a pointer with a newly introduced "Load Guarded" (LGG)
+or "Load Logical and Shift Guarded" (LLGFSG) instructions will cause
+a range check on the loaded value and invoke a (previously set up)
+user-space handler if one of the guarded regions is affected.
+.P
+The
+.\" The command description is copied from v4.12-rc1~139^2~56^2 commit message
+.I command
+argument indicates which function to perform.
+The following commands are supported:
+.TP
+.B GS_ENABLE
+Enable the guarded storage facility for the calling task.
+The initial content of the guarded storage control block will be all zeros.
+After enablement, user-space code can use the "Load Guarded Storage
+Controls" (LGSC) instruction (or the
+.BR load_gs_cb ()
+function wrapper provided in the
+.I asm/guarded_storage.h
+header) to load an arbitrary control block.
+While a task is enabled, the kernel will save and restore the calling content
+of the guarded storage registers on context switch.
+.TP
+.B GS_DISABLE
+Disables the use of the guarded storage facility for the calling task.
+The kernel will cease to save and restore the content of the guarded storage
+registers, the task-specific content of these registers is lost.
+.TP
+.B GS_SET_BC_CB
+Set a broadcast guarded storage control block to the one provided in the
+.I gs_cb
+argument.
+This is called per thread and associates a specific guarded storage control
+block with the calling task.
+This control block will be used in the broadcast command
+.BR GS_BROADCAST .
+.TP
+.B GS_CLEAR_BC_CB
+Clears the broadcast guarded storage control block.
+The guarded storage control block will no longer have the association
+established by the
+.B GS_SET_BC_CB
+command.
+.TP
+.B GS_BROADCAST
+Sends a broadcast to all thread siblings of the calling task.
+Every sibling that has established a broadcast guarded storage control block
+will load this control block and will be enabled for guarded storage.
+The broadcast guarded storage control block is consumed; a second broadcast
+without a refresh of the stored control block with
+.B GS_SET_BC_CB
+will not have any effect.
+.P
+The
+.I gs_cb
+argument specifies the address of a guarded storage control block structure
+and is currently used only by the
+.B GS_SET_BC_CB
+command; all other aforementioned commands ignore this argument.
+.SH RETURN VALUE
+On success, the return value of
+.BR s390_guarded_storage ()
+is 0.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I command
+was
+.B GS_SET_BC_CB
+and the copying of the guarded storage control block structure pointed by the
+.I gs_cb
+argument has failed.
+.TP
+.B EINVAL
+The value provided in the
+.I command
+argument was not valid.
+.TP
+.B ENOMEM
+.I command
+was one of
+.BR GS_ENABLE " or " GS_SET_BC_CB ,
+and the allocation of a new guarded storage control block has failed.
+.TP
+.B EOPNOTSUPP
+The guarded storage facility is not supported by the hardware.
+.SH STANDARDS
+Linux on s390.
+.SH HISTORY
+.\" 916cda1aa1b412d7cf2991c3af7479544942d121, v4.12-rc1~139^2~56^2
+Linux 4.12.
+System z14.
+.SH NOTES
+The description of the guarded storage facility along with related
+instructions and Guarded Storage Control Block and
+Guarded Storage Event Parameter List structure layouts
+is available in "z/Architecture Principles of Operations"
+beginning from the twelfth edition.
+.P
+The
+.I gs_cb
+structure has a field
+.I gsepla
+(Guarded Storage Event Parameter List Address), which is a user-space pointer
+to a Guarded Storage Event Parameter List structure
+(that contains the address
+of the aforementioned event handler in the
+.I gseha
+field), and its layout is available as a
+.B gs_epl
+structure type definition in the
+.I asm/guarded_storage.h
+header.
+.\" .P
+.\" For the example of using the guarded storage facility, see
+.\" .UR https://developer.ibm.com/javasdk/2017/09/25/concurrent-scavenge-using-guarded-storage-facility-works/
+.\" the article with the description of its usage in the Java Garbage Collection
+.\" .UE
+.SH SEE ALSO
+.BR syscall (2)
diff --git a/man/man2/s390_pci_mmio_read.2 b/man/man2/s390_pci_mmio_read.2
new file mode 100644
index 000000000..dedc39050
--- /dev/null
+++ b/man/man2/s390_pci_mmio_read.2
@@ -0,0 +1 @@
+.so man2/s390_pci_mmio_write.2
diff --git a/man/man2/s390_pci_mmio_write.2 b/man/man2/s390_pci_mmio_write.2
new file mode 100644
index 000000000..00875f20a
--- /dev/null
+++ b/man/man2/s390_pci_mmio_write.2
@@ -0,0 +1,94 @@
+.\" Copyright (c) IBM Corp. 2015
+.\" Author: Alexey Ishchuk <aishchuk@linux.vnet.ibm.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH s390_pci_mmio_write 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+s390_pci_mmio_write, s390_pci_mmio_read \- transfer data to/from PCI
+MMIO memory page
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_s390_pci_mmio_write, unsigned long " mmio_addr ,
+.BI "                       const void " user_buffer [. length "], \
+size_t " length );
+.BI "int syscall(SYS_s390_pci_mmio_read, unsigned long " mmio_addr ,
+.BI "                       void " user_buffer [. length "], size_t " length );
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR s390_pci_mmio_write ()
+system call writes
+.I length
+bytes of data from the user-space buffer
+.I user_buffer
+to the PCI MMIO memory location specified by
+.IR mmio_addr .
+The
+.BR s390_pci_mmio_read ()
+system call reads
+.I length
+bytes of
+data from the PCI MMIO memory location specified by
+.I mmio_addr
+to the user-space buffer
+.IR user_buffer .
+.P
+These system calls must be used instead of the simple assignment
+or data-transfer operations that are used to access the PCI MMIO
+memory areas mapped to user space on the Linux System z platform.
+The address specified by
+.I mmio_addr
+must belong to a PCI MMIO memory page mapping in the caller's address space,
+and the data being written or read must not cross a page boundary.
+The
+.I length
+value cannot be greater than the system page size.
+.SH RETURN VALUE
+On success,
+.BR s390_pci_mmio_write ()
+and
+.BR s390_pci_mmio_read ()
+return 0.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+The address in
+.I mmio_addr
+is invalid.
+.TP
+.B EFAULT
+.I user_buffer
+does not point to a valid location in the caller's address space.
+.TP
+.B EINVAL
+Invalid
+.I length
+argument.
+.TP
+.B ENODEV
+PCI support is not enabled.
+.TP
+.B ENOMEM
+Insufficient memory.
+.SH STANDARDS
+Linux on s390.
+.SH HISTORY
+Linux 3.19.
+System z EC12.
+.SH SEE ALSO
+.BR syscall (2)
diff --git a/man/man2/s390_runtime_instr.2 b/man/man2/s390_runtime_instr.2
new file mode 100644
index 000000000..cb52fd43d
--- /dev/null
+++ b/man/man2/s390_runtime_instr.2
@@ -0,0 +1,104 @@
+.\" Copyright (c) IBM Corp. 2012
+.\" Author: Jan Glauber <jang@linux.vnet.ibm.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH s390_runtime_instr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+s390_runtime_instr \- enable/disable s390 CPU run-time instrumentation
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <asm/runtime_instr.h>" " /* Definition of " S390_* " constants */"
+.BR "#include <sys/syscall.h>" "       /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_s390_runtime_instr, int " command ", int " signum );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR s390_runtime_instr (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR s390_runtime_instr ()
+system call starts or stops CPU run-time instrumentation for the
+calling thread.
+.P
+The
+.I command
+argument controls whether run-time instrumentation is started
+.RB ( S390_RUNTIME_INSTR_START ,
+1) or stopped
+.RB ( S390_RUNTIME_INSTR_STOP ,
+2) for the calling thread.
+.P
+The
+.I signum
+argument specifies the number of a real-time signal.
+This argument was used to specify a signal number that should be delivered
+to the thread if the run-time instrumentation buffer was full or if
+the run-time-instrumentation-halted interrupt had occurred.
+This feature was never used,
+and in Linux 4.4 support for this feature was removed;
+.\" commit b38feccd663b55ab07116208b68e1ffc7c3c7e78
+thus, in current kernels, this argument is ignored.
+.SH RETURN VALUE
+On success,
+.BR s390_runtime_instr ()
+returns 0 and enables the thread for
+run-time instrumentation by assigning the thread a default run-time
+instrumentation control block.
+The caller can then read and modify the control block and start the run-time
+instrumentation.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The value specified in
+.I command
+is not a valid command.
+.TP
+.B EINVAL
+The value specified in
+.I signum
+is not a real-time signal number.
+From Linux 4.4 onwards, the
+.I signum
+argument has no effect,
+so that an invalid signal number will not result in an error.
+.TP
+.B ENOMEM
+Allocating memory for the run-time instrumentation control block failed.
+.TP
+.B EOPNOTSUPP
+The run-time instrumentation facility is not available.
+.SH STANDARDS
+Linux on s390.
+.SH HISTORY
+Linux 3.7.
+System z EC12.
+.SH NOTES
+The
+.I asm/runtime_instr.h
+header file is available
+.\" commit df2f815a7df7edb5335a3bdeee6a8f9f6f9c35c4
+since Linux 4.16.
+.P
+Starting with Linux 4.4,
+support for signalling was removed, as was the check whether
+.I signum
+is a valid real-time signal.
+For backwards compatibility with older kernels, it is recommended to pass
+a valid real-time signal number in
+.I signum
+and install a handler for that signal.
+.SH SEE ALSO
+.BR syscall (2),
+.BR signal (7)
diff --git a/man/man2/s390_sthyi.2 b/man/man2/s390_sthyi.2
new file mode 100644
index 000000000..9e0ebb0b7
--- /dev/null
+++ b/man/man2/s390_sthyi.2
@@ -0,0 +1,133 @@
+.\" Copyright IBM Corp. 2017
+.\" Author: QingFeng Hao <haoqf@linux.vnet.ibm.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH s390_sthyi 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+s390_sthyi \- emulate STHYI instruction
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <asm/sthyi.h>" "        /* Definition of " STHYI_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_s390_sthyi, unsigned long " function_code ,
+.BI "            void *" resp_buffer ", uint64_t *" return_code ,
+.BI "            unsigned long " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR s390_sthyi (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR s390_sthyi ()
+system call emulates the STHYI (Store Hypervisor Information) instruction.
+It provides hardware resource information for the machine and its
+virtualization levels.
+This includes CPU type and capacity, as well as the machine model and
+other metrics.
+.P
+The
+.I function_code
+argument indicates which function to perform.
+The following code(s) are supported:
+.TP
+.B STHYI_FC_CP_IFL_CAP
+Return CP (Central Processor) and IFL (Integrated Facility for Linux)
+capacity information.
+.P
+The
+.I resp_buffer
+argument specifies the address of a response buffer.
+When the
+.I function_code
+is
+.BR STHYI_FC_CP_IFL_CAP ,
+the buffer must be one page (4K) in size.
+If the system call returns 0,
+the response buffer will be filled with CPU capacity information.
+Otherwise, the response buffer's content is unchanged.
+.P
+The
+.I return_code
+argument stores the return code of the STHYI instruction,
+using one of the following values:
+.TP
+0
+Success.
+.TP
+4
+Unsupported function code.
+.P
+For further details about
+.IR return_code ,
+.IR function_code ,
+and
+.IR resp_buffer ,
+see the reference given in NOTES.
+.P
+The
+.I flags
+argument is provided to allow for future extensions and currently
+must be set to 0.
+.SH RETURN VALUE
+On success (that is: emulation succeeded), the return value of
+.BR s390_sthyi ()
+matches the condition code of the STHYI instructions, which is a value
+in the range [0..3].
+A return value of 0 indicates that CPU capacity information is stored in
+.IR *resp_buffer .
+A return value of 3 indicates "unsupported function code" and the content of
+.I *resp_buffer
+is unchanged.
+The return values 1 and 2 are reserved.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+The value specified in
+.I resp_buffer
+or
+.I return_code
+is not a valid address.
+.TP
+.B EINVAL
+The value specified in
+.I flags
+is nonzero.
+.TP
+.B ENOMEM
+Allocating memory for handling the CPU capacity information failed.
+.TP
+.B EOPNOTSUPP
+The value specified in
+.I function_code
+is not valid.
+.SH STANDARDS
+Linux on s390.
+.SH HISTORY
+Linux 4.15.
+.SH NOTES
+For details of the STHYI instruction, see
+.UR https://www.ibm.com\:/support\:/knowledgecenter\:/SSB27U_6.3.0\:/com.ibm.zvm.v630.hcpb4\:/hcpb4sth.htm
+the documentation page
+.UE .
+.P
+When the system call interface is used, the response buffer doesn't
+have to fulfill alignment requirements described in the STHYI
+instruction definition.
+.P
+The kernel caches the response (for up to one second, as of Linux 4.16).
+Subsequent system call invocations may return the cached response.
+.SH SEE ALSO
+.BR syscall (2)
diff --git a/man/man2/sbrk.2 b/man/man2/sbrk.2
new file mode 100644
index 000000000..a3711a537
--- /dev/null
+++ b/man/man2/sbrk.2
@@ -0,0 +1 @@
+.so man2/brk.2
diff --git a/man/man2/sched_get_priority_max.2 b/man/man2/sched_get_priority_max.2
new file mode 100644
index 000000000..c94f11051
--- /dev/null
+++ b/man/man2/sched_get_priority_max.2
@@ -0,0 +1,112 @@
+.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
+.\"            First version written
+.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"            revision
+.\"
+.TH sched_get_priority_max 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_get_priority_max, sched_get_priority_min  \- get static priority range
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sched.h>
+.P
+.BI "int sched_get_priority_max(int " policy );
+.BI "int sched_get_priority_min(int " policy );
+.fi
+.SH DESCRIPTION
+.BR sched_get_priority_max ()
+returns the maximum priority value that can be used with the
+scheduling algorithm identified by
+.IR policy .
+.BR sched_get_priority_min ()
+returns the minimum priority value that can be used with the
+scheduling algorithm identified by
+.IR policy .
+Supported
+.I policy
+values are
+.BR SCHED_FIFO ,
+.BR SCHED_RR ,
+.BR SCHED_OTHER ,
+.BR SCHED_BATCH ,
+.BR SCHED_IDLE ,
+and
+.BR SCHED_DEADLINE .
+Further details about these policies can be found in
+.BR sched (7).
+.P
+Processes with numerically higher priority values are scheduled before
+processes with numerically lower priority values.
+Thus, the value
+returned by
+.BR sched_get_priority_max ()
+will be greater than the
+value returned by
+.BR sched_get_priority_min ().
+.P
+Linux allows the static priority range 1 to 99 for the
+.B SCHED_FIFO
+and
+.B SCHED_RR
+policies, and the priority 0 for the remaining policies.
+Scheduling priority ranges for the various policies
+are not alterable.
+.P
+The range of scheduling priorities may vary on other POSIX systems,
+thus it is a good idea for portable applications to use a virtual
+priority range and map it to the interval given by
+.BR sched_get_priority_max ()
+and
+.BR sched_get_priority_min ()
+POSIX.1 requires
+.\" POSIX.1-2001, POSIX.1-2008 (XBD 2.8.4)
+a spread of at least 32 between the maximum and the minimum values for
+.B SCHED_FIFO
+and
+.BR SCHED_RR .
+.P
+POSIX systems on which
+.BR sched_get_priority_max ()
+and
+.BR sched_get_priority_min ()
+are available define
+.B _POSIX_PRIORITY_SCHEDULING
+in
+.IR <unistd.h> .
+.SH RETURN VALUE
+On success,
+.BR sched_get_priority_max ()
+and
+.BR sched_get_priority_min ()
+return the maximum/minimum priority value for the named scheduling
+policy.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The argument
+.I policy
+does not identify a defined scheduling policy.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.ad l
+.nh
+.BR sched_getaffinity (2),
+.BR sched_getparam (2),
+.BR sched_getscheduler (2),
+.BR sched_setaffinity (2),
+.BR sched_setparam (2),
+.BR sched_setscheduler (2),
+.BR sched (7)
diff --git a/man/man2/sched_get_priority_min.2 b/man/man2/sched_get_priority_min.2
new file mode 100644
index 000000000..17b99f0e3
--- /dev/null
+++ b/man/man2/sched_get_priority_min.2
@@ -0,0 +1 @@
+.so man2/sched_get_priority_max.2
diff --git a/man/man2/sched_getaffinity.2 b/man/man2/sched_getaffinity.2
new file mode 100644
index 000000000..f376c11f4
--- /dev/null
+++ b/man/man2/sched_getaffinity.2
@@ -0,0 +1 @@
+.so man2/sched_setaffinity.2
diff --git a/man/man2/sched_getattr.2 b/man/man2/sched_getattr.2
new file mode 100644
index 000000000..cb2c346ee
--- /dev/null
+++ b/man/man2/sched_getattr.2
@@ -0,0 +1 @@
+.so man2/sched_setattr.2
diff --git a/man/man2/sched_getparam.2 b/man/man2/sched_getparam.2
new file mode 100644
index 000000000..d39facd91
--- /dev/null
+++ b/man/man2/sched_getparam.2
@@ -0,0 +1 @@
+.so man2/sched_setparam.2
diff --git a/man/man2/sched_getscheduler.2 b/man/man2/sched_getscheduler.2
new file mode 100644
index 000000000..13aa82793
--- /dev/null
+++ b/man/man2/sched_getscheduler.2
@@ -0,0 +1 @@
+.so man2/sched_setscheduler.2
diff --git a/man/man2/sched_rr_get_interval.2 b/man/man2/sched_rr_get_interval.2
new file mode 100644
index 000000000..3b70285a9
--- /dev/null
+++ b/man/man2/sched_rr_get_interval.2
@@ -0,0 +1,110 @@
+.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
+.\"            First version written
+.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"            revision
+.\"
+.TH sched_rr_get_interval 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_rr_get_interval \- get the SCHED_RR interval for the named process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sched.h>
+.P
+.BI "int sched_rr_get_interval(pid_t " pid ", struct timespec *" tp );
+.fi
+.SH DESCRIPTION
+.BR sched_rr_get_interval ()
+writes into the
+.BR timespec (3)
+structure pointed to by
+.I tp
+the round-robin time quantum for the process identified by
+.IR pid .
+The specified process should be running under the
+.B SCHED_RR
+scheduling policy.
+.P
+If
+.I pid
+is zero, the time quantum for the calling process is written into
+.IR *tp .
+.\" FIXME . On Linux, sched_rr_get_interval()
+.\" returns the timeslice for SCHED_OTHER processes -- this timeslice
+.\" is influenced by the nice value.
+.\" For SCHED_FIFO processes, this always returns 0.
+.\"
+.\" The round-robin time quantum value is not alterable under Linux
+.\" 1.3.81.
+.\"
+.SH RETURN VALUE
+On success,
+.BR sched_rr_get_interval ()
+returns 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Problem with copying information to user space.
+.TP
+.B EINVAL
+Invalid pid.
+.TP
+.B ENOSYS
+The system call is not yet implemented (only on rather old kernels).
+.TP
+.B ESRCH
+Could not find a process with the ID
+.IR pid .
+.SH VERSIONS
+.SS Linux
+Linux 3.9 added
+.\" commit ce0dbbbb30aee6a835511d5be446462388ba9eee
+a new mechanism for adjusting (and viewing) the
+.B SCHED_RR
+quantum: the
+.I /proc/sys/kernel/sched_rr_timeslice_ms
+file exposes the quantum as a millisecond value, whose default is 100.
+Writing 0 to this file resets the quantum to the default value.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SS Linux
+POSIX does not specify any mechanism for controlling the size of the
+round-robin time quantum.
+Older Linux kernels provide a (nonportable) method of doing this.
+The quantum can be controlled by adjusting the process's nice value (see
+.BR setpriority (2)).
+Assigning a negative (i.e., high) nice value results in a longer quantum;
+assigning a positive (i.e., low) nice value results in a shorter quantum.
+The default quantum is 0.1 seconds;
+the degree to which changing the nice value affects the
+quantum has varied somewhat across kernel versions.
+This method of adjusting the quantum was removed
+.\" commit a4ec24b48ddef1e93f7578be53270f0b95ad666c
+starting with Linux 2.6.24.
+.SH NOTES
+POSIX systems on which
+.BR sched_rr_get_interval ()
+is available define
+.B _POSIX_PRIORITY_SCHEDULING
+in
+.IR <unistd.h> .
+.\" .SH BUGS
+.\" As of Linux 1.3.81
+.\" .BR sched_rr_get_interval ()
+.\" returns with error
+.\" ENOSYS, because SCHED_RR has not yet been fully implemented and tested
+.\" properly.
+.SH SEE ALSO
+.BR timespec (3),
+.BR sched (7)
diff --git a/man/man2/sched_setaffinity.2 b/man/man2/sched_setaffinity.2
new file mode 100644
index 000000000..7f87fabb1
--- /dev/null
+++ b/man/man2/sched_setaffinity.2
@@ -0,0 +1,427 @@
+.\" Copyright (C) 2002 Robert Love
+.\" and Copyright (C) 2006, 2015 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2002-11-19 Robert Love <rml@tech9.net> - initial version
+.\" 2004-04-20 mtk - fixed description of return value
+.\" 2004-04-22 aeb - added glibc prototype history
+.\" 2005-05-03 mtk - noted that sched_setaffinity may cause thread
+.\"	migration and that CPU affinity is a per-thread attribute.
+.\" 2006-02-03 mtk -- Major rewrite
+.\" 2008-11-12, mtk, removed CPU_*() macro descriptions to a
+.\" separate CPU_SET(3) page.
+.\"
+.TH sched_setaffinity 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_setaffinity, sched_getaffinity \- \
+set and get a thread's CPU affinity mask
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sched.h>
+.P
+.BI "int sched_setaffinity(pid_t " pid ", size_t " cpusetsize ,
+.BI "                      const cpu_set_t *" mask );
+.BI "int sched_getaffinity(pid_t " pid ", size_t " cpusetsize ,
+.BI "                      cpu_set_t *" mask );
+.fi
+.SH DESCRIPTION
+A thread's CPU affinity mask determines the set of CPUs on which
+it is eligible to run.
+On a multiprocessor system, setting the CPU affinity mask
+can be used to obtain performance benefits.
+For example,
+by dedicating one CPU to a particular thread
+(i.e., setting the affinity mask of that thread to specify a single CPU,
+and setting the affinity mask of all other threads to exclude that CPU),
+it is possible to ensure maximum execution speed for that thread.
+Restricting a thread to run on a single CPU also avoids
+the performance cost caused by the cache invalidation that occurs
+when a thread ceases to execute on one CPU and then
+recommences execution on a different CPU.
+.P
+A CPU affinity mask is represented by the
+.I cpu_set_t
+structure, a "CPU set", pointed to by
+.IR mask .
+A set of macros for manipulating CPU sets is described in
+.BR CPU_SET (3).
+.P
+.BR sched_setaffinity ()
+sets the CPU affinity mask of the thread whose ID is
+.I pid
+to the value specified by
+.IR mask .
+If
+.I pid
+is zero, then the calling thread is used.
+The argument
+.I cpusetsize
+is the length (in bytes) of the data pointed to by
+.IR mask .
+Normally this argument would be specified as
+.IR "sizeof(cpu_set_t)" .
+.P
+If the thread specified by
+.I pid
+is not currently running on one of the CPUs specified in
+.IR mask ,
+then that thread is migrated to one of the CPUs specified in
+.IR mask .
+.P
+.BR sched_getaffinity ()
+writes the affinity mask of the thread whose ID is
+.I pid
+into the
+.I cpu_set_t
+structure pointed to by
+.IR mask .
+The
+.I cpusetsize
+argument specifies the size (in bytes) of
+.IR mask .
+If
+.I pid
+is zero, then the mask of the calling thread is returned.
+.SH RETURN VALUE
+On success,
+.BR sched_setaffinity ()
+and
+.BR sched_getaffinity ()
+return 0 (but see "C library/kernel differences" below,
+which notes that the underlying
+.BR sched_getaffinity ()
+differs in its return value).
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+A supplied memory address was invalid.
+.TP
+.B EINVAL
+The affinity bit mask
+.I mask
+contains no processors that are currently physically on the system
+and permitted to the thread according to any restrictions that
+may be imposed by
+.I cpuset
+cgroups or the "cpuset" mechanism described in
+.BR cpuset (7).
+.TP
+.B EINVAL
+.RB ( sched_getaffinity ()
+and, before Linux 2.6.9,
+.BR sched_setaffinity ())
+.I cpusetsize
+is smaller than the size of the affinity mask used by the kernel.
+.TP
+.B EPERM
+.RB ( sched_setaffinity ())
+The calling thread does not have appropriate privileges.
+The caller needs an effective user ID equal to the real user ID
+or effective user ID of the thread identified by
+.IR pid ,
+or it must possess the
+.B CAP_SYS_NICE
+capability in the user namespace of the thread
+.IR pid .
+.TP
+.B ESRCH
+The thread whose ID is \fIpid\fP could not be found.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.8,
+glibc 2.3.
+.P
+Initially, the glibc interfaces included a
+.I cpusetsize
+argument, typed as
+.IR "unsigned int" .
+In glibc 2.3.3, the
+.I cpusetsize
+argument was removed, but was then restored in glibc 2.3.4, with type
+.IR size_t .
+.SH NOTES
+After a call to
+.BR sched_setaffinity (),
+the set of CPUs on which the thread will actually run is
+the intersection of the set specified in the
+.I mask
+argument and the set of CPUs actually present on the system.
+The system may further restrict the set of CPUs on which the thread
+runs if the "cpuset" mechanism described in
+.BR cpuset (7)
+is being used.
+These restrictions on the actual set of CPUs on which the thread
+will run are silently imposed by the kernel.
+.P
+There are various ways of determining the number of CPUs
+available on the system, including: inspecting the contents of
+.IR /proc/cpuinfo ;
+using
+.BR sysconf (3)
+to obtain the values of the
+.B _SC_NPROCESSORS_CONF
+and
+.B _SC_NPROCESSORS_ONLN
+parameters; and inspecting the list of CPU directories under
+.IR /sys/devices/system/cpu/ .
+.P
+.BR sched (7)
+has a description of the Linux scheduling scheme.
+.P
+The affinity mask is a per-thread attribute that can be
+adjusted independently for each of the threads in a thread group.
+The value returned from a call to
+.BR gettid (2)
+can be passed in the argument
+.IR pid .
+Specifying
+.I pid
+as 0 will set the attribute for the calling thread,
+and passing the value returned from a call to
+.BR getpid (2)
+will set the attribute for the main thread of the thread group.
+(If you are using the POSIX threads API, then use
+.BR pthread_setaffinity_np (3)
+instead of
+.BR sched_setaffinity ().)
+.P
+The
+.I isolcpus
+boot option can be used to isolate one or more CPUs at boot time,
+so that no processes are scheduled onto those CPUs.
+Following the use of this boot option,
+the only way to schedule processes onto the isolated CPUs is via
+.BR sched_setaffinity ()
+or the
+.BR cpuset (7)
+mechanism.
+For further information, see the kernel source file
+.IR Documentation/admin\-guide/kernel\-parameters.txt .
+As noted in that file,
+.I isolcpus
+is the preferred mechanism of isolating CPUs
+(versus the alternative of manually setting the CPU affinity
+of all processes on the system).
+.P
+A child created via
+.BR fork (2)
+inherits its parent's CPU affinity mask.
+The affinity mask is preserved across an
+.BR execve (2).
+.SS C library/kernel differences
+This manual page describes the glibc interface for the CPU affinity calls.
+The actual system call interface is slightly different, with the
+.I mask
+being typed as
+.IR "unsigned long\ *" ,
+reflecting the fact that the underlying implementation of CPU
+sets is a simple bit mask.
+.P
+On success, the raw
+.BR sched_getaffinity ()
+system call returns the number of bytes placed copied into the
+.I mask
+buffer;
+this will be the minimum of
+.I cpusetsize
+and the size (in bytes) of the
+.I cpumask_t
+data type that is used internally by the kernel to
+represent the CPU set bit mask.
+.SS Handling systems with large CPU affinity masks
+The underlying system calls (which represent CPU masks as bit masks of type
+.IR "unsigned long\ *" )
+impose no restriction on the size of the CPU mask.
+However, the
+.I cpu_set_t
+data type used by glibc has a fixed size of 128 bytes,
+meaning that the maximum CPU number that can be represented is 1023.
+.\" FIXME . See https://sourceware.org/bugzilla/show_bug.cgi?id=15630
+.\" and https://sourceware.org/ml/libc-alpha/2013-07/msg00288.html
+If the kernel CPU affinity mask is larger than 1024,
+then calls of the form:
+.P
+.in +4n
+.EX
+sched_getaffinity(pid, sizeof(cpu_set_t), &mask);
+.EE
+.in
+.P
+fail with the error
+.BR EINVAL ,
+the error produced by the underlying system call for the case where the
+.I mask
+size specified in
+.I cpusetsize
+is smaller than the size of the affinity mask used by the kernel.
+(Depending on the system CPU topology, the kernel affinity mask can
+be substantially larger than the number of active CPUs in the system.)
+.P
+When working on systems with large kernel CPU affinity masks,
+one must dynamically allocate the
+.I mask
+argument (see
+.BR CPU_ALLOC (3)).
+Currently, the only way to do this is by probing for the size
+of the required mask using
+.BR sched_getaffinity ()
+calls with increasing mask sizes (until the call does not fail with the error
+.BR EINVAL ).
+.P
+Be aware that
+.BR CPU_ALLOC (3)
+may allocate a slightly larger CPU set than requested
+(because CPU sets are implemented as bit masks allocated in units of
+.IR sizeof(long) ).
+Consequently,
+.BR sched_getaffinity ()
+can set bits beyond the requested allocation size, because the kernel
+sees a few additional bits.
+Therefore, the caller should iterate over the bits in the returned set,
+counting those which are set, and stop upon reaching the value returned by
+.BR CPU_COUNT (3)
+(rather than iterating over the number of bits
+requested to be allocated).
+.SH EXAMPLES
+The program below creates a child process.
+The parent and child then each assign themselves to a specified CPU
+and execute identical loops that consume some CPU time.
+Before terminating, the parent waits for the child to complete.
+The program takes three command-line arguments:
+the CPU number for the parent,
+the CPU number for the child,
+and the number of loop iterations that both processes should perform.
+.P
+As the sample runs below demonstrate, the amount of real and CPU time
+consumed when running the program will depend on intra-core caching effects
+and whether the processes are using the same CPU.
+.P
+We first employ
+.BR lscpu (1)
+to determine that this (x86)
+system has two cores, each with two CPUs:
+.P
+.in +4n
+.EX
+$ \fBlscpu | egrep \-i \[aq]core.*:|socket\[aq]\fP
+Thread(s) per core:    2
+Core(s) per socket:    2
+Socket(s):             1
+.EE
+.in
+.P
+We then time the operation of the example program for three cases:
+both processes running on the same CPU;
+both processes running on different CPUs on the same core;
+and both processes running on different CPUs on different cores.
+.P
+.in +4n
+.EX
+$ \fBtime \-p ./a.out 0 0 100000000\fP
+real 14.75
+user 3.02
+sys 11.73
+$ \fBtime \-p ./a.out 0 1 100000000\fP
+real 11.52
+user 3.98
+sys 19.06
+$ \fBtime \-p ./a.out 0 3 100000000\fP
+real 7.89
+user 3.29
+sys 12.07
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (sched_setaffinity.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int           parentCPU, childCPU;
+    cpu_set_t     set;
+    unsigned int  nloops;
+\&
+    if (argc != 4) {
+        fprintf(stderr, "Usage: %s parent\-cpu child\-cpu num\-loops\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    parentCPU = atoi(argv[1]);
+    childCPU = atoi(argv[2]);
+    nloops = atoi(argv[3]);
+\&
+    CPU_ZERO(&set);
+\&
+    switch (fork()) {
+    case \-1:            /* Error */
+        err(EXIT_FAILURE, "fork");
+\&
+    case 0:             /* Child */
+        CPU_SET(childCPU, &set);
+\&
+        if (sched_setaffinity(getpid(), sizeof(set), &set) == \-1)
+            err(EXIT_FAILURE, "sched_setaffinity");
+\&
+        for (unsigned int j = 0; j < nloops; j++)
+            getppid();
+\&
+        exit(EXIT_SUCCESS);
+\&
+    default:            /* Parent */
+        CPU_SET(parentCPU, &set);
+\&
+        if (sched_setaffinity(getpid(), sizeof(set), &set) == \-1)
+            err(EXIT_FAILURE, "sched_setaffinity");
+\&
+        for (unsigned int j = 0; j < nloops; j++)
+            getppid();
+\&
+        wait(NULL);     /* Wait for child to terminate */
+        exit(EXIT_SUCCESS);
+    }
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR lscpu (1),
+.BR nproc (1),
+.BR taskset (1),
+.BR clone (2),
+.BR getcpu (2),
+.BR getpriority (2),
+.BR gettid (2),
+.BR nice (2),
+.BR sched_get_priority_max (2),
+.BR sched_get_priority_min (2),
+.BR sched_getscheduler (2),
+.BR sched_setscheduler (2),
+.BR setpriority (2),
+.BR CPU_SET (3),
+.BR get_nprocs (3),
+.BR pthread_setaffinity_np (3),
+.BR sched_getcpu (3),
+.BR capabilities (7),
+.BR cpuset (7),
+.BR sched (7),
+.BR numactl (8)
diff --git a/man/man2/sched_setattr.2 b/man/man2/sched_setattr.2
new file mode 100644
index 000000000..5d7061bd6
--- /dev/null
+++ b/man/man2/sched_setattr.2
@@ -0,0 +1,447 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2014 Peter Zijlstra <peterz@infradead.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sched_setattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_setattr, sched_getattr \-
+set and get scheduling policy and attributes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sched.h>" "            /* Definition of " SCHED_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_sched_setattr, pid_t " pid ", struct sched_attr *" attr ,
+.BI "            unsigned int " flags );
+.BI "int syscall(SYS_sched_getattr, pid_t " pid ", struct sched_attr *" attr ,
+.BI "            unsigned int " size ", unsigned int " flags );
+.fi
+.\" FIXME . Add feature test macro requirements
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.SS sched_setattr()
+The
+.BR sched_setattr ()
+system call sets the scheduling policy and
+associated attributes for the thread whose ID is specified in
+.IR pid .
+If
+.I pid
+equals zero,
+the scheduling policy and attributes of the calling thread will be set.
+.P
+Currently, Linux supports the following "normal"
+(i.e., non-real-time) scheduling policies as values that may be specified in
+.IR policy :
+.TP 14
+.B SCHED_OTHER
+the standard round-robin time-sharing policy;
+.\" In the 2.6 kernel sources, SCHED_OTHER is actually called
+.\" SCHED_NORMAL.
+.TP
+.B SCHED_BATCH
+for "batch" style execution of processes; and
+.TP
+.B SCHED_IDLE
+for running
+.I very
+low priority background jobs.
+.P
+Various "real-time" policies are also supported,
+for special time-critical applications that need precise control over
+the way in which runnable threads are selected for execution.
+For the rules governing when a process may use these policies, see
+.BR sched (7).
+The real-time policies that may be specified in
+.I policy
+are:
+.TP 14
+.B SCHED_FIFO
+a first-in, first-out policy; and
+.TP
+.B SCHED_RR
+a round-robin policy.
+.P
+Linux also provides the following policy:
+.TP 14
+.B SCHED_DEADLINE
+a deadline scheduling policy; see
+.BR sched (7)
+for details.
+.P
+The
+.I attr
+argument is a pointer to a structure that defines
+the new scheduling policy and attributes for the specified thread.
+This structure has the following form:
+.P
+.in +4n
+.EX
+struct sched_attr {
+    u32 size;              /* Size of this structure */
+    u32 sched_policy;      /* Policy (SCHED_*) */
+    u64 sched_flags;       /* Flags */
+    s32 sched_nice;        /* Nice value (SCHED_OTHER,
+                              SCHED_BATCH) */
+    u32 sched_priority;    /* Static priority (SCHED_FIFO,
+                              SCHED_RR) */
+    /* Remaining fields are for SCHED_DEADLINE */
+    u64 sched_runtime;
+    u64 sched_deadline;
+    u64 sched_period;
+};
+.EE
+.in
+.P
+The fields of the
+.I sched_attr
+structure are as follows:
+.TP
+.B size
+This field should be set to the size of the structure in bytes, as in
+.IR "sizeof(struct sched_attr)" .
+If the provided structure is smaller than the kernel structure,
+any additional fields are assumed to be '0'.
+If the provided structure is larger than the kernel structure,
+the kernel verifies that all additional fields are 0;
+if they are not,
+.BR sched_setattr ()
+fails with the error
+.B E2BIG
+and updates
+.I size
+to contain the size of the kernel structure.
+.IP
+The above behavior when the size of the user-space
+.I sched_attr
+structure does not match the size of the kernel structure
+allows for future extensibility of the interface.
+Malformed applications that pass oversize structures
+won't break in the future if the size of the kernel
+.I sched_attr
+structure is increased.
+In the future,
+it could also allow applications that know about a larger user-space
+.I sched_attr
+structure to determine whether they are running on an older kernel
+that does not support the larger structure.
+.TP
+.I sched_policy
+This field specifies the scheduling policy, as one of the
+.B SCHED_*
+values listed above.
+.TP
+.I sched_flags
+This field contains zero or more of the following flags
+that are ORed together to control scheduling behavior:
+.RS
+.TP
+.B SCHED_FLAG_RESET_ON_FORK
+Children created by
+.BR fork (2)
+do not inherit privileged scheduling policies.
+See
+.BR sched (7)
+for details.
+.TP
+.BR SCHED_FLAG_RECLAIM " (since Linux 4.13)"
+.\" 2d4283e9d583a3ee8cfb1cbb9c1270614df4c29d
+This flag allows a
+.B SCHED_DEADLINE
+thread to reclaim bandwidth unused by other real-time threads.
+.\" Bandwidth reclaim is done via the GRUB algorithm; see
+.\" Documentation/scheduler/sched-deadline.txt
+.TP
+.BR SCHED_FLAG_DL_OVERRUN " (since Linux 4.16)"
+.\" commit 34be39305a77b8b1ec9f279163c7cdb6cc719b91
+This flag allows an application to get informed about run-time overruns in
+.B SCHED_DEADLINE
+threads.
+Such overruns may be caused by (for example) coarse execution time accounting
+or incorrect parameter assignment.
+Notification takes the form of a
+.B SIGXCPU
+signal which is generated on each overrun.
+.IP
+This
+.B SIGXCPU
+signal is
+.I process-directed
+(see
+.BR signal (7))
+rather than thread-directed.
+This is probably a bug.
+On the one hand,
+.BR sched_setattr ()
+is being used to set a per-thread attribute.
+On the other hand, if the process-directed signal is delivered to
+a thread inside the process other than the one that had a run-time overrun,
+the application has no way of knowing which thread overran.
+.RE
+.TP
+.I sched_nice
+This field specifies the nice value to be set when specifying
+.I sched_policy
+as
+.B SCHED_OTHER
+or
+.BR SCHED_BATCH .
+The nice value is a number in the range \-20 (high priority)
+to +19 (low priority); see
+.BR sched (7).
+.TP
+.I sched_priority
+This field specifies the static priority to be set when specifying
+.I sched_policy
+as
+.B SCHED_FIFO
+or
+.BR SCHED_RR .
+The allowed range of priorities for these policies can be determined using
+.BR sched_get_priority_min (2)
+and
+.BR sched_get_priority_max (2).
+For other policies, this field must be specified as 0.
+.TP
+.I sched_runtime
+This field specifies the "Runtime" parameter for deadline scheduling.
+The value is expressed in nanoseconds.
+This field, and the next two fields,
+are used only for
+.B SCHED_DEADLINE
+scheduling; for further details, see
+.BR sched (7).
+.TP
+.I sched_deadline
+This field specifies the "Deadline" parameter for deadline scheduling.
+The value is expressed in nanoseconds.
+.TP
+.I sched_period
+This field specifies the "Period" parameter for deadline scheduling.
+The value is expressed in nanoseconds.
+.P
+The
+.I flags
+argument is provided to allow for future extensions to the interface;
+in the current implementation it must be specified as 0.
+.\"
+.\"
+.SS sched_getattr()
+The
+.BR sched_getattr ()
+system call fetches the scheduling policy and the
+associated attributes for the thread whose ID is specified in
+.IR pid .
+If
+.I pid
+equals zero,
+the scheduling policy and attributes of the calling thread
+will be retrieved.
+.P
+The
+.I size
+argument should be set to the size of the
+.I sched_attr
+structure as known to user space.
+The value must be at least as large as the size of the initially published
+.I sched_attr
+structure, or the call fails with the error
+.BR EINVAL .
+.P
+The retrieved scheduling attributes are placed in the fields of the
+.I sched_attr
+structure pointed to by
+.IR attr .
+The kernel sets
+.I attr.size
+to the size of its
+.I sched_attr
+structure.
+.P
+If the caller-provided
+.I attr
+buffer is larger than the kernel's
+.I sched_attr
+structure,
+the additional bytes in the user-space structure are not touched.
+If the caller-provided structure is smaller than the kernel
+.I sched_attr
+structure, the kernel will silently not return any values which would be stored
+outside the provided space.
+As with
+.BR sched_setattr (),
+these semantics allow for future extensibility of the interface.
+.P
+The
+.I flags
+argument is provided to allow for future extensions to the interface;
+in the current implementation it must be specified as 0.
+.SH RETURN VALUE
+On success,
+.BR sched_setattr ()
+and
+.BR sched_getattr ()
+return 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR sched_getattr ()
+and
+.BR sched_setattr ()
+can both fail for the following reasons:
+.TP
+.B EINVAL
+.I attr
+is NULL; or
+.I pid
+is negative; or
+.I flags
+is not zero.
+.TP
+.B ESRCH
+The thread whose ID is
+.I pid
+could not be found.
+.P
+In addition,
+.BR sched_getattr ()
+can fail for the following reasons:
+.TP
+.B E2BIG
+The buffer specified by
+.I size
+and
+.I attr
+is too small.
+.TP
+.B EINVAL
+.I size
+is invalid; that is, it is smaller than the initial version of the
+.I sched_attr
+structure (48 bytes) or larger than the system page size.
+.P
+In addition,
+.BR sched_setattr ()
+can fail for the following reasons:
+.TP
+.B E2BIG
+The buffer specified by
+.I size
+and
+.I attr
+is larger than the kernel structure,
+and one or more of the excess bytes is nonzero.
+.TP
+.B EBUSY
+.B SCHED_DEADLINE
+admission control failure, see
+.BR sched (7).
+.TP
+.B EINVAL
+.I attr.sched_policy
+is not one of the recognized policies;
+.I attr.sched_flags
+contains a flag other than
+.BR SCHED_FLAG_RESET_ON_FORK ;
+or
+.I attr.sched_priority
+is invalid; or
+.I attr.sched_policy
+is
+.B SCHED_DEADLINE
+and the deadline scheduling parameters in
+.I attr
+are invalid.
+.TP
+.B EPERM
+The caller does not have appropriate privileges.
+.TP
+.B EPERM
+The CPU affinity mask of the thread specified by
+.I pid
+does not include all CPUs in the system
+(see
+.BR sched_setaffinity (2)).
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.14.
+.\" FIXME . Add glibc version
+.SH NOTES
+glibc does not provide wrappers for these system calls; call them using
+.BR syscall (2).
+.P
+.BR sched_setattr ()
+provides a superset of the functionality of
+.BR sched_setscheduler (2),
+.BR sched_setparam (2),
+.BR nice (2),
+and (other than the ability to set the priority of all processes
+belonging to a specified user or all processes in a specified group)
+.BR setpriority (2).
+Analogously,
+.BR sched_getattr ()
+provides a superset of the functionality of
+.BR sched_getscheduler (2),
+.BR sched_getparam (2),
+and (partially)
+.BR getpriority (2).
+.SH BUGS
+In Linux versions up to
+.\" FIXME . patch sent to Peter Zijlstra
+3.15,
+.BR sched_setattr ()
+failed with the error
+.B EFAULT
+instead of
+.B E2BIG
+for the case described in ERRORS.
+.P
+Up to Linux 5.3,
+.BR sched_getattr ()
+failed with the error
+.B EFBIG
+if the in-kernel
+.I sched_attr
+structure was larger than the
+.I size
+passed by user space.
+.\" In Linux versions up to up 3.15,
+.\" FIXME . patch from Peter Zijlstra pending
+.\" .BR sched_setattr ()
+.\" allowed a negative
+.\" .I attr.sched_policy
+.\" value.
+.SH SEE ALSO
+.ad l
+.nh
+.BR chrt (1),
+.BR nice (2),
+.BR sched_get_priority_max (2),
+.BR sched_get_priority_min (2),
+.BR sched_getaffinity (2),
+.BR sched_getparam (2),
+.BR sched_getscheduler (2),
+.BR sched_rr_get_interval (2),
+.BR sched_setaffinity (2),
+.BR sched_setparam (2),
+.BR sched_setscheduler (2),
+.BR sched_yield (2),
+.BR setpriority (2),
+.BR pthread_getschedparam (3),
+.BR pthread_setschedparam (3),
+.BR pthread_setschedprio (3),
+.BR capabilities (7),
+.BR cpuset (7),
+.BR sched (7)
+.ad
diff --git a/man/man2/sched_setparam.2 b/man/man2/sched_setparam.2
new file mode 100644
index 000000000..20aff7aa1
--- /dev/null
+++ b/man/man2/sched_setparam.2
@@ -0,0 +1,121 @@
+.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
+.\"            First version written
+.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"            revision
+.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH sched_setparam 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_setparam, sched_getparam \- set and get scheduling parameters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sched.h>
+.P
+.BI "int sched_setparam(pid_t " pid ", const struct sched_param *" param );
+.BI "int sched_getparam(pid_t " pid ", struct sched_param *" param );
+.P
+\fBstruct sched_param {
+    ...
+    int \fIsched_priority\fB;
+    ...
+};
+.fi
+.SH DESCRIPTION
+.BR sched_setparam ()
+sets the scheduling parameters associated with the scheduling policy
+for the thread whose thread ID is specified in \fIpid\fP.
+If \fIpid\fP is zero, then
+the parameters of the calling thread are set.
+The interpretation of
+the argument \fIparam\fP depends on the scheduling
+policy of the thread identified by
+.IR pid .
+See
+.BR sched (7)
+for a description of the scheduling policies supported under Linux.
+.P
+.BR sched_getparam ()
+retrieves the scheduling parameters for the
+thread identified by \fIpid\fP.
+If \fIpid\fP is zero, then the parameters
+of the calling thread are retrieved.
+.P
+.BR sched_setparam ()
+checks the validity of \fIparam\fP for the scheduling policy of the
+thread.
+The value \fIparam\->sched_priority\fP must lie within the
+range given by
+.BR sched_get_priority_min (2)
+and
+.BR sched_get_priority_max (2).
+.P
+For a discussion of the privileges and resource limits related to
+scheduling priority and policy, see
+.BR sched (7).
+.P
+POSIX systems on which
+.BR sched_setparam ()
+and
+.BR sched_getparam ()
+are available define
+.B _POSIX_PRIORITY_SCHEDULING
+in \fI<unistd.h>\fP.
+.SH RETURN VALUE
+On success,
+.BR sched_setparam ()
+and
+.BR sched_getparam ()
+return 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+Invalid arguments:
+.I param
+is NULL or
+.I pid
+is negative
+.TP
+.B EINVAL
+.RB ( sched_setparam ())
+The argument \fIparam\fP does not make sense for the current
+scheduling policy.
+.TP
+.B EPERM
+.RB ( sched_setparam ())
+The caller does not have appropriate privileges
+(Linux: does not have the
+.B CAP_SYS_NICE
+capability).
+.TP
+.B ESRCH
+The thread whose ID is \fIpid\fP could not be found.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.ad l
+.nh
+.BR getpriority (2),
+.BR gettid (2),
+.BR nice (2),
+.BR sched_get_priority_max (2),
+.BR sched_get_priority_min (2),
+.BR sched_getaffinity (2),
+.BR sched_getscheduler (2),
+.BR sched_setaffinity (2),
+.BR sched_setattr (2),
+.BR sched_setscheduler (2),
+.BR setpriority (2),
+.BR capabilities (7),
+.BR sched (7)
diff --git a/man/man2/sched_setscheduler.2 b/man/man2/sched_setscheduler.2
new file mode 100644
index 000000000..b22dd76d5
--- /dev/null
+++ b/man/man2/sched_setscheduler.2
@@ -0,0 +1,232 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH sched_setscheduler 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_setscheduler, sched_getscheduler \-
+set and get scheduling policy/parameters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sched.h>
+.P
+.BI "int sched_setscheduler(pid_t " pid ", int " policy ,
+.BI "                       const struct sched_param *" param );
+.BI "int sched_getscheduler(pid_t " pid );
+.fi
+.SH DESCRIPTION
+The
+.BR sched_setscheduler ()
+system call
+sets both the scheduling policy and parameters for the
+thread whose ID is specified in \fIpid\fP.
+If \fIpid\fP equals zero, the
+scheduling policy and parameters of the calling thread will be set.
+.P
+The scheduling parameters are specified in the
+.I param
+argument, which is a pointer to a structure of the following form:
+.P
+.in +4n
+.EX
+struct sched_param {
+    ...
+    int sched_priority;
+    ...
+};
+.EE
+.in
+.P
+In the current implementation, the structure contains only one field,
+.IR sched_priority .
+The interpretation of
+.I param
+depends on the selected policy.
+.P
+Currently, Linux supports the following "normal"
+(i.e., non-real-time) scheduling policies as values that may be specified in
+.IR policy :
+.TP 14
+.B SCHED_OTHER
+the standard round-robin time-sharing policy;
+.\" In the 2.6 kernel sources, SCHED_OTHER is actually called
+.\" SCHED_NORMAL.
+.TP
+.B SCHED_BATCH
+for "batch" style execution of processes; and
+.TP
+.B SCHED_IDLE
+for running
+.I very
+low priority background jobs.
+.P
+For each of the above policies,
+.I param\->sched_priority
+must be 0.
+.P
+Various "real-time" policies are also supported,
+for special time-critical applications that need precise control over
+the way in which runnable threads are selected for execution.
+For the rules governing when a process may use these policies, see
+.BR sched (7).
+The real-time policies that may be specified in
+.I policy
+are:
+.TP 14
+.B SCHED_FIFO
+a first-in, first-out policy; and
+.TP
+.B SCHED_RR
+a round-robin policy.
+.P
+For each of the above policies,
+.I param\->sched_priority
+specifies a scheduling priority for the thread.
+This is a number in the range returned by calling
+.BR sched_get_priority_min (2)
+and
+.BR sched_get_priority_max (2)
+with the specified
+.IR policy .
+On Linux, these system calls return, respectively, 1 and 99.
+.P
+Since Linux 2.6.32, the
+.B SCHED_RESET_ON_FORK
+flag can be ORed in
+.I policy
+when calling
+.BR sched_setscheduler ().
+As a result of including this flag, children created by
+.BR fork (2)
+do not inherit privileged scheduling policies.
+See
+.BR sched (7)
+for details.
+.P
+.BR sched_getscheduler ()
+returns the current scheduling policy of the thread
+identified by \fIpid\fP.
+If \fIpid\fP equals zero, the policy of the
+calling thread will be retrieved.
+.SH RETURN VALUE
+On success,
+.BR sched_setscheduler ()
+returns zero.
+On success,
+.BR sched_getscheduler ()
+returns the policy for the thread (a nonnegative integer).
+On error, both calls return \-1, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+Invalid arguments:
+.I pid
+is negative or
+.I param
+is NULL.
+.TP
+.B EINVAL
+.RB ( sched_setscheduler ())
+.I policy
+is not one of the recognized policies.
+.TP
+.B EINVAL
+.RB ( sched_setscheduler ())
+.I param
+does not make sense for the specified
+.IR policy .
+.TP
+.B EPERM
+The calling thread does not have appropriate privileges.
+.TP
+.B ESRCH
+The thread whose ID is \fIpid\fP could not be found.
+.SH VERSIONS
+POSIX.1 does not detail the permissions that an unprivileged
+thread requires in order to call
+.BR sched_setscheduler (),
+and details vary across systems.
+For example, the Solaris 7 manual page says that
+the real or effective user ID of the caller must
+match the real user ID or the save set-user-ID of the target.
+.P
+The scheduling policy and parameters are in fact per-thread
+attributes on Linux.
+The value returned from a call to
+.BR gettid (2)
+can be passed in the argument
+.IR pid .
+Specifying
+.I pid
+as 0 will operate on the attributes of the calling thread,
+and passing the value returned from a call to
+.BR getpid (2)
+will operate on the attributes of the main thread of the thread group.
+(If you are using the POSIX threads API, then use
+.BR pthread_setschedparam (3),
+.BR pthread_getschedparam (3),
+and
+.BR pthread_setschedprio (3),
+instead of the
+.BR sched_* (2)
+system calls.)
+.SH STANDARDS
+POSIX.1-2008 (but see BUGS below).
+.P
+.B SCHED_BATCH
+and
+.B SCHED_IDLE
+are Linux-specific.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+Further details of the semantics of all of the above "normal"
+and "real-time" scheduling policies can be found in the
+.BR sched (7)
+manual page.
+That page also describes an additional policy,
+.BR SCHED_DEADLINE ,
+which is settable only via
+.BR sched_setattr (2).
+.P
+POSIX systems on which
+.BR sched_setscheduler ()
+and
+.BR sched_getscheduler ()
+are available define
+.B _POSIX_PRIORITY_SCHEDULING
+in \fI<unistd.h>\fP.
+.SH BUGS
+POSIX.1 says that on success,
+.BR sched_setscheduler ()
+should return the previous scheduling policy.
+Linux
+.BR sched_setscheduler ()
+does not conform to this requirement,
+since it always returns 0 on success.
+.SH SEE ALSO
+.ad l
+.nh
+.BR chrt (1),
+.BR nice (2),
+.BR sched_get_priority_max (2),
+.BR sched_get_priority_min (2),
+.BR sched_getaffinity (2),
+.BR sched_getattr (2),
+.BR sched_getparam (2),
+.BR sched_rr_get_interval (2),
+.BR sched_setaffinity (2),
+.BR sched_setattr (2),
+.BR sched_setparam (2),
+.BR sched_yield (2),
+.BR setpriority (2),
+.BR capabilities (7),
+.BR cpuset (7),
+.BR sched (7)
+.ad
diff --git a/man/man2/sched_yield.2 b/man/man2/sched_yield.2
new file mode 100644
index 000000000..4a926a747
--- /dev/null
+++ b/man/man2/sched_yield.2
@@ -0,0 +1,76 @@
+.\" Copyright (C) Tom Bjorkholm & Markus Kuhn, 1996
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1996-04-01 Tom Bjorkholm <tomb@mydata.se>
+.\"            First version written
+.\" 1996-04-10 Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"            revision
+.\"
+.TH sched_yield 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_yield \- yield the processor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sched.h>
+.P
+.B int sched_yield(void);
+.fi
+.SH DESCRIPTION
+.BR sched_yield ()
+causes the calling thread to relinquish the CPU.
+The thread is moved to the end of the queue for its static
+priority and a new thread gets to run.
+.SH RETURN VALUE
+On success,
+.BR sched_yield ()
+returns 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+In the Linux implementation,
+.BR sched_yield ()
+always succeeds.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001 (but optional).
+POSIX.1-2008.
+.P
+Before POSIX.1-2008,
+systems on which
+.BR sched_yield ()
+is available defined
+.B _POSIX_PRIORITY_SCHEDULING
+in
+.IR <unistd.h> .
+.SH CAVEATS
+.BR sched_yield ()
+is intended for use with real-time scheduling policies (i.e.,
+.B SCHED_FIFO
+or
+.BR SCHED_RR ).
+Use of
+.BR sched_yield ()
+with nondeterministic scheduling policies such as
+.B SCHED_OTHER
+is unspecified and very likely means your application design is broken.
+.P
+If the calling thread is the only thread in the highest
+priority list at that time,
+it will continue to run after a call to
+.BR sched_yield ().
+.P
+Avoid calling
+.BR sched_yield ()
+unnecessarily or inappropriately
+(e.g., when resources needed by other
+schedulable threads are still held by the caller),
+since doing so will result in unnecessary context switches,
+which will degrade system performance.
+.SH SEE ALSO
+.BR sched (7)
diff --git a/man/man2/seccomp.2 b/man/man2/seccomp.2
new file mode 100644
index 000000000..25376c3bf
--- /dev/null
+++ b/man/man2/seccomp.2
@@ -0,0 +1,1245 @@
+.\" Copyright (C) 2014 Kees Cook <keescook@chromium.org>
+.\" and Copyright (C) 2012 Will Drewry <wad@chromium.org>
+.\" and Copyright (C) 2008, 2014,2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2017 Tyler Hicks <tyhicks@canonical.com>
+.\" and Copyright (C) 2020 Tycho Andersen <tycho@tycho.ws>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH seccomp 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+seccomp \- operate on Secure Computing state of the process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/seccomp.h>" "  /* Definition of " SECCOMP_* " constants */"
+.BR "#include <linux/filter.h>" "   /* Definition of " "struct sock_fprog" " */"
+.BR "#include <linux/audit.h>" "    /* Definition of " AUDIT_* " constants */"
+.BR "#include <linux/signal.h>" "   /* Definition of " SIG* " constants */"
+.BR "#include <sys/ptrace.h>" "     /* Definition of " PTRACE_* " constants */"
+.\" Kees Cook noted: Anything that uses SECCOMP_RET_TRACE returns will
+.\"                  need <sys/ptrace.h>
+.BR "#include <sys/syscall.h>" "    /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_seccomp, unsigned int " operation ", unsigned int " flags ,
+.BI "            void *" args );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR seccomp (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR seccomp ()
+system call operates on the Secure Computing (seccomp) state of the
+calling process.
+.P
+Currently, Linux supports the following
+.I operation
+values:
+.TP
+.B SECCOMP_SET_MODE_STRICT
+The only system calls that the calling thread is permitted to make are
+.BR read (2),
+.BR write (2),
+.BR _exit (2)
+(but not
+.BR exit_group (2)),
+and
+.BR sigreturn (2).
+Other system calls result in the termination of the calling thread,
+or termination of the entire process with the
+.B SIGKILL
+signal when there is only one thread.
+Strict secure computing mode is useful for number-crunching
+applications that may need to execute untrusted byte code, perhaps
+obtained by reading from a pipe or socket.
+.IP
+Note that although the calling thread can no longer call
+.BR sigprocmask (2),
+it can use
+.BR sigreturn (2)
+to block all signals apart from
+.B SIGKILL
+and
+.BR SIGSTOP .
+This means that
+.BR alarm (2)
+(for example) is not sufficient for restricting the process's execution time.
+Instead, to reliably terminate the process,
+.B SIGKILL
+must be used.
+This can be done by using
+.BR timer_create (2)
+with
+.B SIGEV_SIGNAL
+and
+.I sigev_signo
+set to
+.BR SIGKILL ,
+or by using
+.BR setrlimit (2)
+to set the hard limit for
+.BR RLIMIT_CPU .
+.IP
+This operation is available only if the kernel is configured with
+.B CONFIG_SECCOMP
+enabled.
+.IP
+The value of
+.I flags
+must be 0, and
+.I args
+must be NULL.
+.IP
+This operation is functionally identical to the call:
+.IP
+.in +4n
+.EX
+prctl(PR_SET_SECCOMP, SECCOMP_MODE_STRICT);
+.EE
+.in
+.TP
+.B SECCOMP_SET_MODE_FILTER
+The system calls allowed are defined by a pointer to a Berkeley Packet
+Filter (BPF) passed via
+.IR args .
+This argument is a pointer to a
+.IR "struct\~sock_fprog" ;
+it can be designed to filter arbitrary system calls and system call
+arguments.
+If the filter is invalid,
+.BR seccomp ()
+fails, returning
+.B EINVAL
+in
+.IR errno .
+.IP
+If
+.BR fork (2)
+or
+.BR clone (2)
+is allowed by the filter, any child processes will be constrained to
+the same system call filters as the parent.
+If
+.BR execve (2)
+is allowed,
+the existing filters will be preserved across a call to
+.BR execve (2).
+.IP
+In order to use the
+.B SECCOMP_SET_MODE_FILTER
+operation, either the calling thread must have the
+.B CAP_SYS_ADMIN
+capability in its user namespace, or the thread must already have the
+.I no_new_privs
+bit set.
+If that bit was not already set by an ancestor of this thread,
+the thread must make the following call:
+.IP
+.in +4n
+.EX
+prctl(PR_SET_NO_NEW_PRIVS, 1);
+.EE
+.in
+.IP
+Otherwise, the
+.B SECCOMP_SET_MODE_FILTER
+operation fails and returns
+.B EACCES
+in
+.IR errno .
+This requirement ensures that an unprivileged process cannot apply
+a malicious filter and then invoke a set-user-ID or
+other privileged program using
+.BR execve (2),
+thus potentially compromising that program.
+(Such a malicious filter might, for example, cause an attempt to use
+.BR setuid (2)
+to set the caller's user IDs to nonzero values to instead
+return 0 without actually making the system call.
+Thus, the program might be tricked into retaining superuser privileges
+in circumstances where it is possible to influence it to do
+dangerous things because it did not actually drop privileges.)
+.IP
+If
+.BR prctl (2)
+or
+.BR seccomp ()
+is allowed by the attached filter, further filters may be added.
+This will increase evaluation time, but allows for further reduction of
+the attack surface during execution of a thread.
+.IP
+The
+.B SECCOMP_SET_MODE_FILTER
+operation is available only if the kernel is configured with
+.B CONFIG_SECCOMP_FILTER
+enabled.
+.IP
+When
+.I flags
+is 0, this operation is functionally identical to the call:
+.IP
+.in +4n
+.EX
+prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, args);
+.EE
+.in
+.IP
+The recognized
+.I flags
+are:
+.RS
+.TP
+.BR SECCOMP_FILTER_FLAG_LOG " (since Linux 4.14)"
+.\" commit e66a39977985b1e69e17c4042cb290768eca9b02
+All filter return actions except
+.B SECCOMP_RET_ALLOW
+should be logged.
+An administrator may override this filter flag by preventing specific
+actions from being logged via the
+.I /proc/sys/kernel/seccomp/actions_logged
+file.
+.TP
+.BR SECCOMP_FILTER_FLAG_NEW_LISTENER " (since Linux 5.0)"
+.\" commit 6a21cc50f0c7f87dae5259f6cfefe024412313f6
+After successfully installing the filter program,
+return a new user-space notification file descriptor.
+(The close-on-exec flag is set for the file descriptor.)
+When the filter returns
+.B SECCOMP_RET_USER_NOTIF
+a notification will be sent to this file descriptor.
+.IP
+At most one seccomp filter using the
+.B SECCOMP_FILTER_FLAG_NEW_LISTENER
+flag can be installed for a thread.
+.IP
+See
+.BR seccomp_unotify (2)
+for further details.
+.TP
+.BR SECCOMP_FILTER_FLAG_SPEC_ALLOW " (since Linux 4.17)"
+.\" commit 00a02d0c502a06d15e07b857f8ff921e3e402675
+Disable Speculative Store Bypass mitigation.
+.TP
+.B SECCOMP_FILTER_FLAG_TSYNC
+When adding a new filter, synchronize all other threads of the calling
+process to the same seccomp filter tree.
+A "filter tree" is the ordered list of filters attached to a thread.
+(Attaching identical filters in separate
+.BR seccomp ()
+calls results in different filters from this perspective.)
+.IP
+If any thread cannot synchronize to the same filter tree,
+the call will not attach the new seccomp filter,
+and will fail, returning the first thread ID found that cannot synchronize.
+Synchronization will fail if another thread in the same process is in
+.B SECCOMP_MODE_STRICT
+or if it has attached new seccomp filters to itself,
+diverging from the calling thread's filter tree.
+.RE
+.TP
+.BR SECCOMP_GET_ACTION_AVAIL " (since Linux 4.14)"
+.\" commit d612b1fd8010d0d67b5287fe146b8b55bcbb8655
+Test to see if an action is supported by the kernel.
+This operation is helpful to confirm that the kernel knows
+of a more recently added filter return action
+since the kernel treats all unknown actions as
+.BR SECCOMP_RET_KILL_PROCESS .
+.IP
+The value of
+.I flags
+must be 0, and
+.I args
+must be a pointer to an unsigned 32-bit filter return action.
+.TP
+.BR SECCOMP_GET_NOTIF_SIZES " (since Linux 5.0)"
+.\" commit 6a21cc50f0c7f87dae5259f6cfefe024412313f6
+Get the sizes of the seccomp user-space notification structures.
+Since these structures may evolve and grow over time,
+this command can be used to determine how
+much memory to allocate for sending and receiving notifications.
+.IP
+The value of
+.I flags
+must be 0, and
+.I args
+must be a pointer to a
+.IR "struct seccomp_notif_sizes" ,
+which has the following form:
+.IP
+.EX
+struct seccomp_notif_sizes
+    __u16 seccomp_notif;      /* Size of notification structure */
+    __u16 seccomp_notif_resp; /* Size of response structure */
+    __u16 seccomp_data;       /* Size of \[aq]struct seccomp_data\[aq] */
+};
+.EE
+.IP
+See
+.BR seccomp_unotify (2)
+for further details.
+.\"
+.SS Filters
+When adding filters via
+.BR SECCOMP_SET_MODE_FILTER ,
+.I args
+points to a filter program:
+.P
+.in +4n
+.EX
+struct sock_fprog {
+    unsigned short      len;    /* Number of BPF instructions */
+    struct sock_filter *filter; /* Pointer to array of
+                                   BPF instructions */
+};
+.EE
+.in
+.P
+Each program must contain one or more BPF instructions:
+.P
+.in +4n
+.EX
+struct sock_filter {            /* Filter block */
+    __u16 code;                 /* Actual filter code */
+    __u8  jt;                   /* Jump true */
+    __u8  jf;                   /* Jump false */
+    __u32 k;                    /* Generic multiuse field */
+};
+.EE
+.in
+.P
+When executing the instructions, the BPF program operates on the
+system call information made available (i.e., use the
+.B BPF_ABS
+addressing mode) as a (read-only)
+.\" Quoting Kees Cook:
+.\"     If BPF even allows changing the data, it's not copied back to
+.\"     the syscall when it runs. Anything wanting to do things like
+.\"     that would need to use ptrace to catch the call and directly
+.\"     modify the registers before continuing with the call.
+buffer of the following form:
+.P
+.in +4n
+.EX
+struct seccomp_data {
+    int   nr;                   /* System call number */
+    __u32 arch;                 /* AUDIT_ARCH_* value
+                                   (see <linux/audit.h>) */
+    __u64 instruction_pointer;  /* CPU instruction pointer */
+    __u64 args[6];              /* Up to 6 system call arguments */
+};
+.EE
+.in
+.P
+Because numbering of system calls varies between architectures and
+some architectures (e.g., x86-64) allow user-space code to use
+the calling conventions of multiple architectures
+(and the convention being used may vary over the life of a process that uses
+.BR execve (2)
+to execute binaries that employ the different conventions),
+it is usually necessary to verify the value of the
+.I arch
+field.
+.P
+It is strongly recommended to use an allow-list approach whenever
+possible because such an approach is more robust and simple.
+A deny-list will have to be updated whenever a potentially
+dangerous system call is added (or a dangerous flag or option if those
+are deny-listed), and it is often possible to alter the
+representation of a value without altering its meaning, leading to
+a deny-list bypass.
+See also
+.I Caveats
+below.
+.P
+The
+.I arch
+field is not unique for all calling conventions.
+The x86-64 ABI and the x32 ABI both use
+.B AUDIT_ARCH_X86_64
+as
+.IR arch ,
+and they run on the same processors.
+Instead, the mask
+.B __X32_SYSCALL_BIT
+is used on the system call number to tell the two ABIs apart.
+.\" As noted by Dave Drysdale in a note at the end of
+.\" https://lwn.net/Articles/604515/
+.\"     One additional detail to point out for the x32 ABI case:
+.\"     the syscall number gets a high bit set (__X32_SYSCALL_BIT),
+.\"     to mark it as an x32 call.
+.\"
+.\"     If x32 support is included in the kernel, then __SYSCALL_MASK
+.\"     will have a value that is not all-ones, and this will trigger
+.\"     an extra instruction in system_call to mask off the extra bit,
+.\"     so that the syscall table indexing still works.
+.P
+This means that a policy must either deny all syscalls with
+.B __X32_SYSCALL_BIT
+or it must recognize syscalls with and without
+.B __X32_SYSCALL_BIT
+set.
+A list of system calls to be denied based on
+.I nr
+that does not also contain
+.I nr
+values with
+.B __X32_SYSCALL_BIT
+set can be bypassed by a malicious program that sets
+.BR __X32_SYSCALL_BIT .
+.P
+Additionally, kernels prior to Linux 5.4 incorrectly permitted
+.I nr
+in the ranges 512-547 as well as the corresponding non-x32 syscalls ORed
+with
+.BR __X32_SYSCALL_BIT .
+For example,
+.I nr
+== 521 and
+.I nr
+== (101 |
+.BR __X32_SYSCALL_BIT )
+would result in invocations of
+.BR ptrace (2)
+with potentially confused x32-vs-x86_64 semantics in the kernel.
+Policies intended to work on kernels before Linux 5.4 must ensure that they
+deny or otherwise correctly handle these system calls.
+On Linux 5.4 and newer,
+.\" commit 6365b842aae4490ebfafadfc6bb27a6d3cc54757
+such system calls will fail with the error
+.BR ENOSYS ,
+without doing anything.
+.P
+The
+.I instruction_pointer
+field provides the address of the machine-language instruction that
+performed the system call.
+This might be useful in conjunction with the use of
+.IR /proc/ pid /maps
+to perform checks based on which region (mapping) of the program
+made the system call.
+(Probably, it is wise to lock down the
+.BR mmap (2)
+and
+.BR mprotect (2)
+system calls to prevent the program from subverting such checks.)
+.P
+When checking values from
+.IR args ,
+keep in mind that arguments are often
+silently truncated before being processed, but after the seccomp check.
+For example, this happens if the i386 ABI is used on an
+x86-64 kernel: although the kernel will normally not look beyond
+the 32 lowest bits of the arguments, the values of the full
+64-bit registers will be present in the seccomp data.
+A less surprising example is that if the x86-64 ABI is used to perform
+a system call that takes an argument of type
+.IR int ,
+the more-significant half of the argument register is ignored by
+the system call, but visible in the seccomp data.
+.P
+A seccomp filter returns a 32-bit value consisting of two parts:
+the most significant 16 bits
+(corresponding to the mask defined by the constant
+.BR SECCOMP_RET_ACTION_FULL )
+contain one of the "action" values listed below;
+the least significant 16-bits (defined by the constant
+.BR SECCOMP_RET_DATA )
+are "data" to be associated with this return value.
+.P
+If multiple filters exist, they are \fIall\fP executed,
+in reverse order of their addition to the filter tree\[em]that is,
+the most recently installed filter is executed first.
+(Note that all filters will be called
+even if one of the earlier filters returns
+.BR SECCOMP_RET_KILL .
+This is done to simplify the kernel code and to provide a
+tiny speed-up in the execution of sets of filters by
+avoiding a check for this uncommon case.)
+.\" From an Aug 2015 conversation with Kees Cook where I asked why *all*
+.\" filters are applied even if one of the early filters returns
+.\" SECCOMP_RET_KILL:
+.\"
+.\"     It's just because it would be an optimization that would only speed up
+.\"     the RET_KILL case, but it's the uncommon one and the one that doesn't
+.\"     benefit meaningfully from such a change (you need to kill the process
+.\"     really quickly?). We would speed up killing a program at the (albeit
+.\"     tiny) expense to all other filtered programs. Best to keep the filter
+.\"     execution logic clear, simple, and as fast as possible for all
+.\"     filters.
+The return value for the evaluation of a given system call is the first-seen
+action value of highest precedence (along with its accompanying data)
+returned by execution of all of the filters.
+.P
+In decreasing order of precedence,
+the action values that may be returned by a seccomp filter are:
+.TP
+.BR SECCOMP_RET_KILL_PROCESS " (since Linux 4.14)"
+.\" commit 4d3b0b05aae9ee9ce0970dc4cc0fb3fad5e85945
+.\" commit 0466bdb99e8744bc9befa8d62a317f0fd7fd7421
+This value results in immediate termination of the process,
+with a core dump.
+The system call is not executed.
+By contrast with
+.B SECCOMP_RET_KILL_THREAD
+below, all threads in the thread group are terminated.
+(For a discussion of thread groups, see the description of the
+.B CLONE_THREAD
+flag in
+.BR clone (2).)
+.IP
+The process terminates
+.I "as though"
+killed by a
+.B SIGSYS
+signal.
+Even if a signal handler has been registered for
+.BR SIGSYS ,
+the handler will be ignored in this case and the process always terminates.
+To a parent process that is waiting on this process (using
+.BR waitpid (2)
+or similar), the returned
+.I wstatus
+will indicate that its child was terminated as though by a
+.B SIGSYS
+signal.
+.TP
+.BR SECCOMP_RET_KILL_THREAD " (or " SECCOMP_RET_KILL )
+This value results in immediate termination of the thread
+that made the system call.
+The system call is not executed.
+Other threads in the same thread group will continue to execute.
+.IP
+The thread terminates
+.I "as though"
+killed by a
+.B SIGSYS
+signal.
+See
+.B SECCOMP_RET_KILL_PROCESS
+above.
+.IP
+.\" See these commits:
+.\" seccomp: dump core when using SECCOMP_RET_KILL
+.\"    (b25e67161c295c98acda92123b2dd1e7d8642901)
+.\" seccomp: Only dump core when single-threaded
+.\"    (d7276e321ff8a53106a59c85ca46d03e34288893)
+Before Linux 4.11,
+any process terminated in this way would not trigger a coredump
+(even though
+.B SIGSYS
+is documented in
+.BR signal (7)
+as having a default action of termination with a core dump).
+Since Linux 4.11,
+a single-threaded process will dump core if terminated in this way.
+.IP
+With the addition of
+.B SECCOMP_RET_KILL_PROCESS
+in Linux 4.14,
+.B SECCOMP_RET_KILL_THREAD
+was added as a synonym for
+.BR SECCOMP_RET_KILL ,
+in order to more clearly distinguish the two actions.
+.IP
+.BR Note :
+the use of
+.B SECCOMP_RET_KILL_THREAD
+to kill a single thread in a multithreaded process is likely to leave the
+process in a permanently inconsistent and possibly corrupt state.
+.TP
+.B SECCOMP_RET_TRAP
+This value results in the kernel sending a thread-directed
+.B SIGSYS
+signal to the triggering thread.
+(The system call is not executed.)
+Various fields will be set in the
+.I siginfo_t
+structure (see
+.BR sigaction (2))
+associated with signal:
+.RS
+.IP \[bu] 3
+.I si_signo
+will contain
+.BR SIGSYS .
+.IP \[bu]
+.I si_call_addr
+will show the address of the system call instruction.
+.IP \[bu]
+.I si_syscall
+and
+.I si_arch
+will indicate which system call was attempted.
+.IP \[bu]
+.I si_code
+will contain
+.BR SYS_SECCOMP .
+.IP \[bu]
+.I si_errno
+will contain the
+.B SECCOMP_RET_DATA
+portion of the filter return value.
+.RE
+.IP
+The program counter will be as though the system call happened
+(i.e., the program counter will not point to the system call instruction).
+The return value register will contain an architecture\-dependent value;
+if resuming execution, set it to something appropriate for the system call.
+(The architecture dependency is because replacing it with
+.B ENOSYS
+could overwrite some useful information.)
+.TP
+.B SECCOMP_RET_ERRNO
+This value results in the
+.B SECCOMP_RET_DATA
+portion of the filter's return value being passed to user space as the
+.I errno
+value without executing the system call.
+.TP
+.BR SECCOMP_RET_USER_NOTIF " (since Linux 5.0)"
+.\" commit 6a21cc50f0c7f87dae5259f6cfefe024412313f6
+Forward the system call to an attached user-space supervisor
+process to allow that process to decide what to do with the system call.
+If there is no attached supervisor (either
+because the filter was not installed with the
+.B SECCOMP_FILTER_FLAG_NEW_LISTENER
+flag or because the file descriptor was closed), the filter returns
+.B ENOSYS
+(similar to what happens when a filter returns
+.B SECCOMP_RET_TRACE
+and there is no tracer).
+See
+.BR seccomp_unotify (2)
+for further details.
+.IP
+Note that the supervisor process will not be notified
+if another filter returns an action value with a precedence greater than
+.BR SECCOMP_RET_USER_NOTIF .
+.TP
+.B SECCOMP_RET_TRACE
+When returned, this value will cause the kernel to attempt to notify a
+.BR ptrace (2)-based
+tracer prior to executing the system call.
+If there is no tracer present,
+the system call is not executed and returns a failure status with
+.I errno
+set to
+.BR ENOSYS .
+.IP
+A tracer will be notified if it requests
+.B PTRACE_O_TRACESECCOMP
+using
+.IR ptrace(PTRACE_SETOPTIONS) .
+The tracer will be notified of a
+.B PTRACE_EVENT_SECCOMP
+and the
+.B SECCOMP_RET_DATA
+portion of the filter's return value will be available to the tracer via
+.BR PTRACE_GETEVENTMSG .
+.IP
+The tracer can skip the system call by changing the system call number
+to \-1.
+Alternatively, the tracer can change the system call
+requested by changing the system call to a valid system call number.
+If the tracer asks to skip the system call, then the system call will
+appear to return the value that the tracer puts in the return value register.
+.IP
+.\" This was changed in ce6526e8afa4.
+.\" A related hole, using PTRACE_SYSCALL instead of SECCOMP_RET_TRACE, was
+.\" changed in arch-specific commits, e.g. 93e35efb8de4 for X86 and
+.\" 0f3912fd934c for ARM.
+Before Linux 4.8, the seccomp check will not be run again after the tracer is
+notified.
+(This means that, on older kernels, seccomp-based sandboxes
+.B "must not"
+allow use of
+.BR ptrace (2)\[em]even
+of other
+sandboxed processes\[em]without extreme care;
+ptracers can use this mechanism to escape from the seccomp sandbox.)
+.IP
+Note that a tracer process will not be notified
+if another filter returns an action value with a precedence greater than
+.BR SECCOMP_RET_TRACE .
+.TP
+.BR SECCOMP_RET_LOG " (since Linux 4.14)"
+.\" commit 59f5cf44a38284eb9e76270c786fb6cc62ef8ac4
+This value results in the system call being executed after
+the filter return action is logged.
+An administrator may override the logging of this action via
+the
+.I /proc/sys/kernel/seccomp/actions_logged
+file.
+.TP
+.B SECCOMP_RET_ALLOW
+This value results in the system call being executed.
+.P
+If an action value other than one of the above is specified,
+then the filter action is treated as either
+.B SECCOMP_RET_KILL_PROCESS
+(since Linux 4.14)
+.\" commit 4d3b0b05aae9ee9ce0970dc4cc0fb3fad5e85945
+or
+.B SECCOMP_RET_KILL_THREAD
+(in Linux 4.13 and earlier).
+.\"
+.SS /proc interfaces
+The files in the directory
+.I /proc/sys/kernel/seccomp
+provide additional seccomp information and configuration:
+.TP
+.IR actions_avail " (since Linux 4.14)"
+.\" commit 8e5f1ad116df6b0de65eac458d5e7c318d1c05af
+A read-only ordered list of seccomp filter return actions in string form.
+The ordering, from left-to-right, is in decreasing order of precedence.
+The list represents the set of seccomp filter return actions
+supported by the kernel.
+.TP
+.IR actions_logged " (since Linux 4.14)"
+.\" commit 0ddec0fc8900201c0897b87b762b7c420436662f
+A read-write ordered list of seccomp filter return actions that
+are allowed to be logged.
+Writes to the file do not need to be in ordered form but reads from
+the file will be ordered in the same way as the
+.I actions_avail
+file.
+.IP
+It is important to note that the value of
+.I actions_logged
+does not prevent certain filter return actions from being logged when
+the audit subsystem is configured to audit a task.
+If the action is not found in the
+.I actions_logged
+file, the final decision on whether to audit the action for that task is
+ultimately left up to the audit subsystem to decide for all filter return
+actions other than
+.BR SECCOMP_RET_ALLOW .
+.IP
+The "allow" string is not accepted in the
+.I actions_logged
+file as it is not possible to log
+.B SECCOMP_RET_ALLOW
+actions.
+Attempting to write "allow" to the file will fail with the error
+.BR EINVAL .
+.\"
+.SS Audit logging of seccomp actions
+.\" commit 59f5cf44a38284eb9e76270c786fb6cc62ef8ac4
+Since Linux 4.14, the kernel provides the facility to log the
+actions returned by seccomp filters in the audit log.
+The kernel makes the decision to log an action based on
+the action type,  whether or not the action is present in the
+.I actions_logged
+file, and whether kernel auditing is enabled
+(e.g., via the kernel boot option
+.IR audit=1 ).
+.\" or auditing could be enabled via the netlink API (AUDIT_SET)
+The rules are as follows:
+.IP \[bu] 3
+If the action is
+.BR SECCOMP_RET_ALLOW ,
+the action is not logged.
+.IP \[bu]
+Otherwise, if the action is either
+.B SECCOMP_RET_KILL_PROCESS
+or
+.BR SECCOMP_RET_KILL_THREAD ,
+and that action appears in the
+.I actions_logged
+file, the action is logged.
+.IP \[bu]
+Otherwise, if the filter has requested logging (the
+.B SECCOMP_FILTER_FLAG_LOG
+flag)
+and the action appears in the
+.I actions_logged
+file, the action is logged.
+.IP \[bu]
+Otherwise, if kernel auditing is enabled and the process is being audited
+.RB ( autrace (8)),
+the action is logged.
+.IP \[bu]
+Otherwise, the action is not logged.
+.SH RETURN VALUE
+On success,
+.BR seccomp ()
+returns 0.
+On error, if
+.B SECCOMP_FILTER_FLAG_TSYNC
+was used,
+the return value is the ID of the thread
+that caused the synchronization failure.
+(This ID is a kernel thread ID of the type returned by
+.BR clone (2)
+and
+.BR gettid (2).)
+On other errors, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR seccomp ()
+can fail for the following reasons:
+.TP
+.B EACCES
+The caller did not have the
+.B CAP_SYS_ADMIN
+capability in its user namespace, or had not set
+.I no_new_privs
+before using
+.BR SECCOMP_SET_MODE_FILTER .
+.TP
+.B EBUSY
+While installing a new filter, the
+.B SECCOMP_FILTER_FLAG_NEW_LISTENER
+flag was specified,
+but a previous filter had already been installed with that flag.
+.TP
+.B EFAULT
+.I args
+was not a valid address.
+.TP
+.B EINVAL
+.I operation
+is unknown or is not supported by this kernel version or configuration.
+.TP
+.B EINVAL
+The specified
+.I flags
+are invalid for the given
+.IR operation .
+.TP
+.B EINVAL
+.I operation
+included
+.BR BPF_ABS ,
+but the specified offset was not aligned to a 32-bit boundary or exceeded
+.IR "sizeof(struct\~seccomp_data)" .
+.TP
+.B EINVAL
+.\" See kernel/seccomp.c::seccomp_may_assign_mode() in Linux 3.18 sources
+A secure computing mode has already been set, and
+.I operation
+differs from the existing setting.
+.TP
+.B EINVAL
+.I operation
+specified
+.BR SECCOMP_SET_MODE_FILTER ,
+but the filter program pointed to by
+.I args
+was not valid or the length of the filter program was zero or exceeded
+.B BPF_MAXINSNS
+(4096) instructions.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ENOMEM
+.\" ENOMEM in kernel/seccomp.c::seccomp_attach_filter() in Linux 3.18 sources
+The total length of all filter programs attached
+to the calling thread would exceed
+.B MAX_INSNS_PER_PATH
+(32768) instructions.
+Note that for the purposes of calculating this limit,
+each already existing filter program incurs an
+overhead penalty of 4 instructions.
+.TP
+.B EOPNOTSUPP
+.I operation
+specified
+.BR SECCOMP_GET_ACTION_AVAIL ,
+but the kernel does not support the filter return action specified by
+.IR args .
+.TP
+.B ESRCH
+Another thread caused a failure during thread sync, but its ID could not
+be determined.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.17.
+.\" FIXME . Add glibc version
+.SH NOTES
+Rather than hand-coding seccomp filters as shown in the example below,
+you may prefer to employ the
+.I libseccomp
+library, which provides a front-end for generating seccomp filters.
+.P
+The
+.I Seccomp
+field of the
+.IR /proc/ pid /status
+file provides a method of viewing the seccomp mode of a process; see
+.BR proc (5).
+.P
+.BR seccomp ()
+provides a superset of the functionality provided by the
+.BR prctl (2)
+.B PR_SET_SECCOMP
+operation (which does not support
+.IR flags ).
+.P
+Since Linux 4.4, the
+.BR ptrace (2)
+.B PTRACE_SECCOMP_GET_FILTER
+operation can be used to dump a process's seccomp filters.
+.\"
+.SS Architecture support for seccomp BPF
+Architecture support for seccomp BPF filtering
+.\" Check by grepping for HAVE_ARCH_SECCOMP_FILTER in Kconfig files in
+.\" kernel source. Last checked in Linux 4.16-rc source.
+is available on the following architectures:
+.IP \[bu] 3
+x86-64, i386, x32 (since Linux 3.5)
+.PD 0
+.IP \[bu]
+ARM (since Linux 3.8)
+.IP \[bu]
+s390 (since Linux 3.8)
+.IP \[bu]
+MIPS (since Linux 3.16)
+.IP \[bu]
+ARM-64 (since Linux 3.19)
+.IP \[bu]
+PowerPC (since Linux 4.3)
+.IP \[bu]
+Tile (since Linux 4.3)
+.IP \[bu]
+PA-RISC (since Linux 4.6)
+.\" User mode Linux since Linux 4.6
+.PD
+.\"
+.SS Caveats
+There are various subtleties to consider when applying seccomp filters
+to a program, including the following:
+.IP \[bu] 3
+Some traditional system calls have user-space implementations in the
+.BR vdso (7)
+on many architectures.
+Notable examples include
+.BR clock_gettime (2),
+.BR gettimeofday (2),
+and
+.BR time (2).
+On such architectures,
+seccomp filtering for these system calls will have no effect.
+(However, there are cases where the
+.BR vdso (7)
+implementations may fall back to invoking the true system call,
+in which case seccomp filters would see the system call.)
+.IP \[bu]
+Seccomp filtering is based on system call numbers.
+However, applications typically do not directly invoke system calls,
+but instead call wrapper functions in the C library which
+in turn invoke the system calls.
+Consequently, one must be aware of the following:
+.RS
+.IP \[bu] 3
+The glibc wrappers for some traditional system calls may actually
+employ system calls with different names in the kernel.
+For example, the
+.BR exit (2)
+wrapper function actually employs the
+.BR exit_group (2)
+system call, and the
+.BR fork (2)
+wrapper function actually calls
+.BR clone (2).
+.IP \[bu]
+The behavior of wrapper functions may vary across architectures,
+according to the range of system calls provided on those architectures.
+In other words, the same wrapper function may invoke
+different system calls on different architectures.
+.IP \[bu]
+Finally, the behavior of wrapper functions can change across glibc versions.
+For example, in older versions, the glibc wrapper function for
+.BR open (2)
+invoked the system call of the same name,
+but starting in glibc 2.26, the implementation switched to calling
+.BR openat (2)
+on all architectures.
+.RE
+.P
+The consequence of the above points is that it may be necessary
+to filter for a system call other than might be expected.
+Various manual pages in Section 2 provide helpful details
+about the differences between wrapper functions and
+the underlying system calls in subsections entitled
+.IR "C library/kernel differences" .
+.P
+Furthermore, note that the application of seccomp filters
+even risks causing bugs in an application,
+when the filters cause unexpected failures for legitimate operations
+that the application might need to perform.
+Such bugs may not easily be discovered when testing the seccomp
+filters if the bugs occur in rarely used application code paths.
+.\"
+.SS Seccomp-specific BPF details
+Note the following BPF details specific to seccomp filters:
+.IP \[bu] 3
+The
+.B BPF_H
+and
+.B BPF_B
+size modifiers are not supported: all operations must load and store
+(4-byte) words
+.RB ( BPF_W ).
+.IP \[bu]
+To access the contents of the
+.I seccomp_data
+buffer, use the
+.B BPF_ABS
+addressing mode modifier.
+.IP \[bu]
+The
+.B BPF_LEN
+addressing mode modifier yields an immediate mode operand
+whose value is the size of the
+.I seccomp_data
+buffer.
+.SH EXAMPLES
+The program below accepts four or more arguments.
+The first three arguments are a system call number,
+a numeric architecture identifier, and an error number.
+The program uses these values to construct a BPF filter
+that is used at run time to perform the following checks:
+.IP \[bu] 3
+If the program is not running on the specified architecture,
+the BPF filter causes system calls to fail with the error
+.BR ENOSYS .
+.IP \[bu]
+If the program attempts to execute the system call with the specified number,
+the BPF filter causes the system call to fail, with
+.I errno
+being set to the specified error number.
+.P
+The remaining command-line arguments specify
+the pathname and additional arguments of a program
+that the example program should attempt to execute using
+.BR execv (3)
+(a library function that employs the
+.BR execve (2)
+system call).
+Some example runs of the program are shown below.
+.P
+First, we display the architecture that we are running on (x86-64)
+and then construct a shell function that looks up system call
+numbers on this architecture:
+.P
+.in +4n
+.EX
+$ \fBuname \-m\fP
+x86_64
+$ \fBsyscall_nr() {
+    cat /usr/src/linux/arch/x86/syscalls/syscall_64.tbl | \e
+    awk \[aq]$2 != "x32" && $3 == "\[aq]$1\[aq]" { print $1 }\[aq]
+}\fP
+.EE
+.in
+.P
+When the BPF filter rejects a system call (case [2] above),
+it causes the system call to fail with the error number
+specified on the command line.
+In the experiments shown here, we'll use error number 99:
+.P
+.in +4n
+.EX
+$ \fBerrno 99\fP
+EADDRNOTAVAIL 99 Cannot assign requested address
+.EE
+.in
+.P
+In the following example, we attempt to run the command
+.BR whoami (1),
+but the BPF filter rejects the
+.BR execve (2)
+system call, so that the command is not even executed:
+.P
+.in +4n
+.EX
+$ \fBsyscall_nr execve\fP
+59
+$ \fB./a.out\fP
+Usage: ./a.out <syscall_nr> <arch> <errno> <prog> [<args>]
+Hint for <arch>: AUDIT_ARCH_I386: 0x40000003
+                 AUDIT_ARCH_X86_64: 0xC000003E
+$ \fB./a.out 59 0xC000003E 99 /bin/whoami\fP
+execv: Cannot assign requested address
+.EE
+.in
+.P
+In the next example, the BPF filter rejects the
+.BR write (2)
+system call, so that, although it is successfully started, the
+.BR whoami (1)
+command is not able to write output:
+.P
+.in +4n
+.EX
+$ \fBsyscall_nr write\fP
+1
+$ \fB./a.out 1 0xC000003E 99 /bin/whoami\fP
+.EE
+.in
+.P
+In the final example,
+the BPF filter rejects a system call that is not used by the
+.BR whoami (1)
+command, so it is able to successfully execute and produce output:
+.P
+.in +4n
+.EX
+$ \fBsyscall_nr preadv\fP
+295
+$ \fB./a.out 295 0xC000003E 99 /bin/whoami\fP
+cecilia
+.EE
+.in
+.SS Program source
+.\" SRC BEGIN (seccomp.c)
+.EX
+#include <linux/audit.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+#define X32_SYSCALL_BIT 0x40000000
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+\&
+static int
+install_filter(int syscall_nr, unsigned int t_arch, int f_errno)
+{
+    unsigned int upper_nr_limit = 0xffffffff;
+\&
+    /* Assume that AUDIT_ARCH_X86_64 means the normal x86\-64 ABI
+       (in the x32 ABI, all system calls have bit 30 set in the
+       \[aq]nr\[aq] field, meaning the numbers are >= X32_SYSCALL_BIT). */
+    if (t_arch == AUDIT_ARCH_X86_64)
+        upper_nr_limit = X32_SYSCALL_BIT \- 1;
+\&
+    struct sock_filter filter[] = {
+        /* [0] Load architecture from \[aq]seccomp_data\[aq] buffer into
+               accumulator. */
+        BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
+                 (offsetof(struct seccomp_data, arch))),
+\&
+        /* [1] Jump forward 5 instructions if architecture does not
+               match \[aq]t_arch\[aq]. */
+        BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, t_arch, 0, 5),
+\&
+        /* [2] Load system call number from \[aq]seccomp_data\[aq] buffer into
+               accumulator. */
+        BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
+                 (offsetof(struct seccomp_data, nr))),
+\&
+        /* [3] Check ABI \- only needed for x86\-64 in deny\-list use
+               cases.  Use BPF_JGT instead of checking against the bit
+               mask to avoid having to reload the syscall number. */
+        BPF_JUMP(BPF_JMP | BPF_JGT | BPF_K, upper_nr_limit, 3, 0),
+\&
+        /* [4] Jump forward 1 instruction if system call number
+               does not match \[aq]syscall_nr\[aq]. */
+        BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, syscall_nr, 0, 1),
+\&
+        /* [5] Matching architecture and system call: don\[aq]t execute
+           the system call, and return \[aq]f_errno\[aq] in \[aq]errno\[aq]. */
+        BPF_STMT(BPF_RET | BPF_K,
+                 SECCOMP_RET_ERRNO | (f_errno & SECCOMP_RET_DATA)),
+\&
+        /* [6] Destination of system call number mismatch: allow other
+               system calls. */
+        BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
+\&
+        /* [7] Destination of architecture mismatch: kill process. */
+        BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_KILL_PROCESS),
+    };
+\&
+    struct sock_fprog prog = {
+        .len = ARRAY_SIZE(filter),
+        .filter = filter,
+    };
+\&
+    if (syscall(SYS_seccomp, SECCOMP_SET_MODE_FILTER, 0, &prog)) {
+        perror("seccomp");
+        return 1;
+    }
+\&
+    return 0;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    if (argc < 5) {
+        fprintf(stderr, "Usage: "
+                "%s <syscall_nr> <arch> <errno> <prog> [<args>]\en"
+                "Hint for <arch>: AUDIT_ARCH_I386: 0x%X\en"
+                "                 AUDIT_ARCH_X86_64: 0x%X\en"
+                "\en", argv[0], AUDIT_ARCH_I386, AUDIT_ARCH_X86_64);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
+        perror("prctl");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (install_filter(strtol(argv[1], NULL, 0),
+                       strtoul(argv[2], NULL, 0),
+                       strtol(argv[3], NULL, 0)))
+        exit(EXIT_FAILURE);
+\&
+    execv(argv[4], &argv[4]);
+    perror("execv");
+    exit(EXIT_FAILURE);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR bpfc (1),
+.BR strace (1),
+.BR bpf (2),
+.BR prctl (2),
+.BR ptrace (2),
+.BR seccomp_unotify (2),
+.BR sigaction (2),
+.BR proc (5),
+.BR signal (7),
+.BR socket (7)
+.P
+Various pages from the
+.I libseccomp
+library, including:
+.BR scmp_sys_resolver (1),
+.BR seccomp_export_bpf (3),
+.BR seccomp_init (3),
+.BR seccomp_load (3),
+and
+.BR seccomp_rule_add (3).
+.P
+The kernel source files
+.I Documentation/networking/filter.txt
+and
+.I Documentation/userspace\-api/seccomp_filter.rst
+.\" commit c061f33f35be0ccc80f4b8e0aea5dfd2ed7e01a3
+(or
+.I Documentation/prctl/seccomp_filter.txt
+before Linux 4.13).
+.P
+McCanne, S.\& and Jacobson, V.\& (1992)
+.IR "The BSD Packet Filter: A New Architecture for User-level Packet Capture" ,
+Proceedings of the USENIX Winter 1993 Conference
+.UR http://www.tcpdump.org/papers/bpf\-usenix93.pdf
+.UE
diff --git a/man/man2/seccomp_unotify.2 b/man/man2/seccomp_unotify.2
new file mode 100644
index 000000000..f11dabf3a
--- /dev/null
+++ b/man/man2/seccomp_unotify.2
@@ -0,0 +1,2011 @@
+.\" Copyright (C) 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH seccomp_unotify 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+seccomp_unotify \- Seccomp user-space notification mechanism
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <linux/seccomp.h>
+.B #include <linux/filter.h>
+.B #include <linux/audit.h>
+.P
+.BI "int seccomp(unsigned int " operation ", unsigned int " flags \
+", void *" args );
+.P
+.B #include <sys/ioctl.h>
+.P
+.BI "int ioctl(int " fd ", SECCOMP_IOCTL_NOTIF_RECV,"
+.BI "          struct seccomp_notif *" req );
+.BI "int ioctl(int " fd ", SECCOMP_IOCTL_NOTIF_SEND,"
+.BI "          struct seccomp_notif_resp *" resp );
+.BI "int ioctl(int " fd ", SECCOMP_IOCTL_NOTIF_ID_VALID, __u64 *" id );
+.BI "int ioctl(int " fd ", SECCOMP_IOCTL_NOTIF_ADDFD,"
+.BI "          struct seccomp_notif_addfd *" addfd );
+.fi
+.SH DESCRIPTION
+This page describes the user-space notification mechanism provided by the
+Secure Computing (seccomp) facility.
+As well as the use of the
+.B SECCOMP_FILTER_FLAG_NEW_LISTENER
+flag, the
+.B SECCOMP_RET_USER_NOTIF
+action value, and the
+.B SECCOMP_GET_NOTIF_SIZES
+operation described in
+.BR seccomp (2),
+this mechanism involves the use of a number of related
+.BR ioctl (2)
+operations (described below).
+.\"
+.SS Overview
+In conventional usage of a seccomp filter,
+the decision about how to treat a system call is made by the filter itself.
+By contrast, the user-space notification mechanism allows
+the seccomp filter to delegate
+the handling of the system call to another user-space process.
+Note that this mechanism is explicitly
+.B not
+intended as a method implementing security policy; see NOTES.
+.P
+In the discussion that follows,
+the thread(s) on which the seccomp filter is installed is (are)
+referred to as the
+.IR target ,
+and the process that is notified by the user-space notification
+mechanism is referred to as the
+.IR supervisor .
+.P
+A suitably privileged supervisor can use the user-space notification
+mechanism to perform actions on behalf of the target.
+The advantage of the user-space notification mechanism is that
+the supervisor will
+usually be able to retrieve information about the target and the
+performed system call that the seccomp filter itself cannot.
+(A seccomp filter is limited in the information it can obtain and
+the actions that it can perform because it
+is running on a virtual machine inside the kernel.)
+.P
+An overview of the steps performed by the target and the supervisor
+is as follows:
+.\"-------------------------------------
+.IP (1) 5
+The target establishes a seccomp filter in the usual manner,
+but with two differences:
+.RS
+.IP \[bu] 3
+The
+.BR seccomp (2)
+.I flags
+argument includes the flag
+.BR SECCOMP_FILTER_FLAG_NEW_LISTENER .
+Consequently, the return value of the (successful)
+.BR seccomp (2)
+call is a new "listening"
+file descriptor that can be used to receive notifications.
+Only one "listening" seccomp filter can be installed for a thread.
+.\" FIXME
+.\" Is the last sentence above correct?
+.\"
+.\" Kees Cook (25 Oct 2020) notes:
+.\"
+.\" I like this limitation, but I expect that it'll need to change in the
+.\" future. Even with LSMs, we see the need for arbitrary stacking, and the
+.\" idea of there being only 1 supervisor will eventually break down. Right
+.\" now there is only 1 because only container managers are using this
+.\" feature. But if some daemon starts using it to isolate some thread,
+.\" suddenly it might break if a container manager is trying to listen to it
+.\" too, etc. I expect it won't be needed soon, but I do think it'll change.
+.\"
+.IP \[bu]
+In cases where it is appropriate, the seccomp filter returns the action value
+.BR SECCOMP_RET_USER_NOTIF .
+This return value will trigger a notification event.
+.RE
+.\"-------------------------------------
+.IP (2)
+In order that the supervisor can obtain notifications
+using the listening file descriptor,
+(a duplicate of) that file descriptor must be passed from
+the target to the supervisor.
+One way in which this could be done is by passing the file descriptor
+over a UNIX domain socket connection between the target and the supervisor
+(using the
+.B SCM_RIGHTS
+ancillary message type described in
+.BR unix (7)).
+Another way to do this is through the use of
+.BR pidfd_getfd (2).
+.\" Jann Horn:
+.\"     Instead of using unix domain sockets to send the fd to the
+.\"     parent, I think you could also use clone3() with
+.\"     flags==CLONE_FILES|SIGCHLD, dup2() the seccomp fd to an fd
+.\"     that was reserved in the parent, call unshare(CLONE_FILES)
+.\"     in the child after setting up the seccomp fd, and wake
+.\"     up the parent with something like pthread_cond_signal()?
+.\"     I'm not sure whether that'd look better or worse in the
+.\"     end though, so maybe just ignore this comment.
+.\"-------------------------------------
+.IP (3)
+The supervisor will receive notification events
+on the listening file descriptor.
+These events are returned as structures of type
+.IR seccomp_notif .
+Because this structure and its size may evolve over kernel versions,
+the supervisor must first determine the size of this structure
+using the
+.BR seccomp (2)
+.B SECCOMP_GET_NOTIF_SIZES
+operation, which returns a structure of type
+.IR seccomp_notif_sizes .
+The supervisor allocates a buffer of size
+.I seccomp_notif_sizes.seccomp_notif
+bytes to receive notification events.
+In addition,the supervisor allocates another buffer of size
+.I seccomp_notif_sizes.seccomp_notif_resp
+bytes for the response (a
+.I struct seccomp_notif_resp
+structure)
+that it will provide to the kernel (and thus the target).
+.\"-------------------------------------
+.IP (4)
+The target then performs its workload,
+which includes system calls that will be controlled by the seccomp filter.
+Whenever one of these system calls causes the filter to return the
+.B SECCOMP_RET_USER_NOTIF
+action value, the kernel does
+.I not
+(yet) execute the system call;
+instead, execution of the target is temporarily blocked inside
+the kernel (in a sleep state that is interruptible by signals)
+and a notification event is generated on the listening file descriptor.
+.\"-------------------------------------
+.IP (5)
+The supervisor can now repeatedly monitor the
+listening file descriptor for
+.BR SECCOMP_RET_USER_NOTIF -triggered
+events.
+To do this, the supervisor uses the
+.B SECCOMP_IOCTL_NOTIF_RECV
+.BR ioctl (2)
+operation to read information about a notification event;
+this operation blocks until an event is available.
+The operation returns a
+.I seccomp_notif
+structure containing information about the system call
+that is being attempted by the target.
+(As described in NOTES,
+the file descriptor can also be monitored with
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7).)
+.\" FIXME
+.\" Christian Brauner:
+.\"
+.\" Do we support O_NONBLOCK with SECCOMP_IOCTL_NOTIF_RECV and if
+.\" not should we?
+.\"
+.\" Michael Kerrisk:
+.\"
+.\" A quick test suggests that O_NONBLOCK has no effect on the blocking
+.\" behavior of SECCOMP_IOCTL_NOTIF_RECV.
+.
+.\"-------------------------------------
+.IP (6)
+The
+.I seccomp_notif
+structure returned by the
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation includes the same information (a
+.I seccomp_data
+structure) that was passed to the seccomp filter.
+This information allows the supervisor to discover the system call number and
+the arguments for the target's system call.
+In addition, the notification event contains the ID of the thread
+that triggered the notification and a unique cookie value that
+is used in subsequent
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+and
+.B SECCOMP_IOCTL_NOTIF_SEND
+operations.
+.IP
+The information in the notification can be used to discover the
+values of pointer arguments for the target's system call.
+(This is something that can't be done from within a seccomp filter.)
+One way in which the supervisor can do this is to open the corresponding
+.IR /proc/ tid /mem
+file (see
+.BR proc (5))
+and read bytes from the location that corresponds to one of
+the pointer arguments whose value is supplied in the notification event.
+.\" Tycho Andersen mentioned that there are alternatives to /proc/PID/mem,
+.\" such as ptrace() and /proc/PID/map_files
+(The supervisor must be careful to avoid
+a race condition that can occur when doing this;
+see the description of the
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+.BR ioctl (2)
+operation below.)
+In addition,
+the supervisor can access other system information that is visible
+in user space but which is not accessible from a seccomp filter.
+.\"-------------------------------------
+.IP (7)
+Having obtained information as per the previous step,
+the supervisor may then choose to perform an action in response
+to the target's system call
+(which, as noted above, is not executed when the seccomp filter returns the
+.B SECCOMP_RET_USER_NOTIF
+action value).
+.IP
+One example use case here relates to containers.
+The target may be located inside a container where
+it does not have sufficient capabilities to mount a filesystem
+in the container's mount namespace.
+However, the supervisor may be a more privileged process that
+does have sufficient capabilities to perform the mount operation.
+.\"-------------------------------------
+.IP (8)
+The supervisor then sends a response to the notification.
+The information in this response is used by the kernel to construct
+a return value for the target's system call and provide
+a value that will be assigned to the
+.I errno
+variable of the target.
+.IP
+The response is sent using the
+.B SECCOMP_IOCTL_NOTIF_SEND
+.BR ioctl (2)
+operation, which is used to transmit a
+.I seccomp_notif_resp
+structure to the kernel.
+This structure includes a cookie value that the supervisor obtained in the
+.I seccomp_notif
+structure returned by the
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation.
+This cookie value allows the kernel to associate the response with the
+target.
+This structure must include the cookie value that the supervisor
+obtained in the
+.I seccomp_notif
+structure returned by the
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation;
+the cookie allows the kernel to associate the response with the target.
+.\"-------------------------------------
+.IP (9)
+Once the notification has been sent,
+the system call in the target thread unblocks,
+returning the information that was provided by the supervisor
+in the notification response.
+.\"-------------------------------------
+.P
+As a variation on the last two steps,
+the supervisor can send a response that tells the kernel that it
+should execute the target thread's system call; see the discussion of
+.BR SECCOMP_USER_NOTIF_FLAG_CONTINUE ,
+below.
+.\"
+.SH IOCTL OPERATIONS
+The following
+.BR ioctl (2)
+operations are supported by the seccomp user-space
+notification file descriptor.
+For each of these operations, the first (file descriptor) argument of
+.BR ioctl (2)
+is the listening file descriptor returned by a call to
+.BR seccomp (2)
+with the
+.B SECCOMP_FILTER_FLAG_NEW_LISTENER
+flag.
+.\"
+.SS SECCOMP_IOCTL_NOTIF_RECV
+The
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation (available since Linux 5.0) is used to obtain a user-space
+notification event.
+If no such event is currently pending,
+the operation blocks until an event occurs.
+The third
+.BR ioctl (2)
+argument is a pointer to a structure of the following form
+which contains information about the event.
+This structure must be zeroed out before the call.
+.P
+.in +4n
+.EX
+struct seccomp_notif {
+    __u64  id;              /* Cookie */
+    __u32  pid;             /* TID of target thread */
+    __u32  flags;           /* Currently unused (0) */
+    struct seccomp_data data;   /* See seccomp(2) */
+};
+.EE
+.in
+.P
+The fields in this structure are as follows:
+.TP
+.I id
+This is a cookie for the notification.
+Each such cookie is guaranteed to be unique for the corresponding
+seccomp filter.
+.RS
+.IP \[bu] 3
+The cookie can be used with the
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+.BR ioctl (2)
+operation described below.
+.IP \[bu]
+When returning a notification response to the kernel,
+the supervisor must include the cookie value in the
+.I seccomp_notif_resp
+structure that is specified as the argument of the
+.B SECCOMP_IOCTL_NOTIF_SEND
+operation.
+.RE
+.TP
+.I pid
+This is the thread ID of the target thread that triggered
+the notification event.
+.TP
+.I flags
+This is a bit mask of flags providing further information on the event.
+In the current implementation, this field is always zero.
+.TP
+.I data
+This is a
+.I seccomp_data
+structure containing information about the system call that
+triggered the notification.
+This is the same structure that is passed to the seccomp filter.
+See
+.BR seccomp (2)
+for details of this structure.
+.P
+On success, this operation returns 0; on failure, \-1 is returned, and
+.I errno
+is set to indicate the cause of the error.
+This operation can fail with the following errors:
+.TP
+.BR EINVAL " (since Linux 5.5)"
+.\" commit 2882d53c9c6f3b8311d225062522f03772cf0179
+The
+.I seccomp_notif
+structure that was passed to the call contained nonzero fields.
+.TP
+.B ENOENT
+The target thread was killed by a signal as the notification information
+was being generated,
+or the target's (blocked) system call was interrupted by a signal handler.
+.\" FIXME
+.\" From my experiments,
+.\" it appears that if a SECCOMP_IOCTL_NOTIF_RECV is done after
+.\" the target thread terminates, then the ioctl() simply
+.\" blocks (rather than returning an error to indicate that the
+.\" target no longer exists).
+.\"
+.\" I found that surprising, and it required some contortions in
+.\" the example program.  It was not possible to code my SIGCHLD
+.\" handler (which reaps the zombie when the worker/target
+.\" terminates) to simply set a flag checked in the main
+.\" handleNotifications() loop, since this created an
+.\" unavoidable race where the child might terminate just after
+.\" I had checked the flag, but before I blocked (forever!) in the
+.\" SECCOMP_IOCTL_NOTIF_RECV operation. Instead, I had to code
+.\" the signal handler to simply call _exit(2) in order to
+.\" terminate the parent process (the supervisor).
+.\"
+.\" Is this expected behavior? It seems to me rather
+.\" desirable that SECCOMP_IOCTL_NOTIF_RECV should give an error
+.\" if the target has terminated.
+.\"
+.\" Jann posted a patch to rectify this, but there was no response
+.\" (Lore link: https://bit.ly/3jvUBxk) to his question about fixing
+.\" this issue. (I've tried building with the patch, but encountered
+.\" an issue with the target process entering D state after a signal.)
+.\"
+.\" For now, this behavior is documented in BUGS.
+.\"
+.\" Kees Cook commented: Let's change [this] ASAP!
+.\"
+.SS SECCOMP_IOCTL_NOTIF_ID_VALID
+The
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+operation (available since Linux 5.0) is used to check that a notification ID
+returned by an earlier
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation is still valid
+(i.e., that the target still exists and its system call
+is still blocked waiting for a response).
+.P
+The third
+.BR ioctl (2)
+argument is a pointer to the cookie
+.RI ( id )
+returned by the
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation.
+.P
+This operation is necessary to avoid race conditions that can occur when the
+.I pid
+returned by the
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation terminates, and that process ID is reused by another process.
+An example of this kind of race is the following
+.IP (1) 5
+A notification is generated on the listening file descriptor.
+The returned
+.I seccomp_notif
+contains the TID of the target thread (in the
+.I pid
+field of the structure).
+.IP (2)
+The target terminates.
+.IP (3)
+Another thread or process is created on the system that by chance reuses the
+TID that was freed when the target terminated.
+.IP (4)
+The supervisor
+.BR open (2)s
+the
+.IR /proc/ tid /mem
+file for the TID obtained in step 1, with the intention of (say)
+inspecting the memory location(s) that containing the argument(s) of
+the system call that triggered the notification in step 1.
+.P
+In the above scenario, the risk is that the supervisor may try
+to access the memory of a process other than the target.
+This race can be avoided by following the call to
+.BR open (2)
+with a
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+operation to verify that the process that generated the notification
+is still alive.
+(Note that if the target terminates after the latter step,
+a subsequent
+.BR read (2)
+from the file descriptor may return 0, indicating end of file.)
+.\" Jann Horn:
+.\"     the PID can be reused, but the /proc/$pid directory is
+.\"     internally not associated with the numeric PID, but,
+.\"     conceptually speaking, with a specific incarnation of the
+.\"     PID, or something like that.  (Actually, it is associated
+.\"     with the "struct pid", which is not reused, instead of the
+.\"     numeric PID.
+.P
+See NOTES for a discussion of other cases where
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+checks must be performed.
+.P
+On success (i.e., the notification ID is still valid),
+this operation returns 0.
+On failure (i.e., the notification ID is no longer valid),
+\-1 is returned, and
+.I errno
+is set to
+.BR ENOENT .
+.\"
+.SS SECCOMP_IOCTL_NOTIF_SEND
+The
+.B SECCOMP_IOCTL_NOTIF_SEND
+operation (available since Linux 5.0)
+is used to send a notification response back to the kernel.
+The third
+.BR ioctl (2)
+argument of this structure is a pointer to a structure of the following form:
+.P
+.in +4n
+.EX
+struct seccomp_notif_resp {
+    __u64 id;           /* Cookie value */
+    __s64 val;          /* Success return value */
+    __s32 error;        /* 0 (success) or negative error number */
+    __u32 flags;        /* See below */
+};
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I id
+This is the cookie value that was obtained using the
+.B SECCOMP_IOCTL_NOTIF_RECV
+operation.
+This cookie value allows the kernel to correctly associate this response
+with the system call that triggered the user-space notification.
+.TP
+.I val
+This is the value that will be used for a spoofed
+success return for the target's system call; see below.
+.TP
+.I error
+This is the value that will be used as the error number
+.RI ( errno )
+for a spoofed error return for the target's system call; see below.
+.TP
+.I flags
+This is a bit mask that includes zero or more of the following flags:
+.RS
+.TP
+.BR SECCOMP_USER_NOTIF_FLAG_CONTINUE " (since Linux 5.5)"
+Tell the kernel to execute the target's system call.
+.\" commit fb3c5386b382d4097476ce9647260fc89b34afdb
+.RE
+.P
+Two kinds of response are possible:
+.IP \[bu] 3
+A response to the kernel telling it to execute the
+target's system call.
+In this case, the
+.I flags
+field includes
+.B SECCOMP_USER_NOTIF_FLAG_CONTINUE
+and the
+.I error
+and
+.I val
+fields must be zero.
+.IP
+This kind of response can be useful in cases where the supervisor needs
+to do deeper analysis of the target's system call than is possible
+from a seccomp filter (e.g., examining the values of pointer arguments),
+and, having decided that the system call does not require emulation
+by the supervisor, the supervisor wants the system call to
+be executed normally in the target.
+.IP
+The
+.B SECCOMP_USER_NOTIF_FLAG_CONTINUE
+flag should be used with caution; see NOTES.
+.IP \[bu]
+A spoofed return value for the target's system call.
+In this case, the kernel does not execute the target's system call,
+instead causing the system call to return a spoofed value as specified by
+fields of the
+.I seccomp_notif_resp
+structure.
+The supervisor should set the fields of this structure as follows:
+.RS
+.IP \[bu] 3
+.I flags
+does not contain
+.BR SECCOMP_USER_NOTIF_FLAG_CONTINUE .
+.IP \[bu]
+.I error
+is set either to 0 for a spoofed "success" return or to a negative
+error number for a spoofed "failure" return.
+In the former case, the kernel causes the target's system call
+to return the value specified in the
+.I val
+field.
+In the latter case, the kernel causes the target's system call
+to return \-1, and
+.I errno
+is assigned the negated
+.I error
+value.
+.IP \[bu]
+.I val
+is set to a value that will be used as the return value for a spoofed
+"success" return for the target's system call.
+The value in this field is ignored if the
+.I error
+field contains a nonzero value.
+.\" FIXME
+.\" Kees Cook suggested:
+.\"
+.\" Strictly speaking, this is architecture specific, but
+.\" all architectures do it this way. Should seccomp enforce
+.\" val == 0 when err != 0 ?
+.\"
+.\" Christian Brauner
+.\"
+.\" Feels like it should, at least for the SEND ioctl where we already
+.\" verify that val and err are both 0 when CONTINUE is specified (as you
+.\" pointed out correctly above).
+.RE
+.P
+On success, this operation returns 0; on failure, \-1 is returned, and
+.I errno
+is set to indicate the cause of the error.
+This operation can fail with the following errors:
+.TP
+.B EINPROGRESS
+A response to this notification has already been sent.
+.TP
+.B EINVAL
+An invalid value was specified in the
+.I flags field.
+.TP
+.B
+.B EINVAL
+The
+.I flags
+field contained
+.BR SECCOMP_USER_NOTIF_FLAG_CONTINUE ,
+and the
+.I error
+or
+.I val
+field was not zero.
+.TP
+.B ENOENT
+The blocked system call in the target
+has been interrupted by a signal handler
+or the target has terminated.
+.\" Jann Horn notes:
+.\"     you could also get this [ENOENT] if a response has already
+.\"     been sent, instead of EINPROGRESS - the only difference is
+.\"     whether the target thread has picked up the response yet
+.\"
+.SS SECCOMP_IOCTL_NOTIF_ADDFD
+The
+.B SECCOMP_IOCTL_NOTIF_ADDFD
+operation (available since Linux 5.9)
+allows the supervisor to install a file descriptor
+into the target's file descriptor table.
+Much like the use of
+.B SCM_RIGHTS
+messages described in
+.BR unix (7),
+this operation is semantically equivalent to duplicating
+a file descriptor from the supervisor's file descriptor table
+into the target's file descriptor table.
+.P
+The
+.B SECCOMP_IOCTL_NOTIF_ADDFD
+operation permits the supervisor to emulate a target system call (such as
+.BR socket (2)
+or
+.BR openat (2))
+that generates a file descriptor.
+The supervisor can perform the system call that generates
+the file descriptor (and associated open file description)
+and then use this operation to allocate
+a file descriptor that refers to the same open file description in the target.
+(For an explanation of open file descriptions, see
+.BR open (2).)
+.P
+Once this operation has been performed,
+the supervisor can close its copy of the file descriptor.
+.P
+In the target,
+the received file descriptor is subject to the same
+Linux Security Module (LSM) checks as are applied to a file descriptor
+that is received in an
+.B SCM_RIGHTS
+ancillary message.
+If the file descriptor refers to a socket,
+it inherits the cgroup version 1 network controller settings
+.RI ( classid
+and
+.IR netprioidx )
+of the target.
+.P
+The third
+.BR ioctl (2)
+argument is a pointer to a structure of the following form:
+.P
+.in +4n
+.EX
+struct seccomp_notif_addfd {
+    __u64 id;           /* Cookie value */
+    __u32 flags;        /* Flags */
+    __u32 srcfd;        /* Local file descriptor number */
+    __u32 newfd;        /* 0 or desired file descriptor
+                           number in target */
+    __u32 newfd_flags;  /* Flags to set on target file
+                           descriptor */
+};
+.EE
+.in
+.P
+The fields in this structure are as follows:
+.TP
+.I id
+This field should be set to the notification ID
+(cookie value) that was obtained via
+.BR SECCOMP_IOCTL_NOTIF_RECV .
+.TP
+.I flags
+This field is a bit mask of flags that modify the behavior of the operation.
+Currently, only one flag is supported:
+.RS
+.TP
+.B SECCOMP_ADDFD_FLAG_SETFD
+When allocating the file descriptor in the target,
+use the file descriptor number specified in the
+.I newfd
+field.
+.TP
+.BR SECCOMP_ADDFD_FLAG_SEND " (since Linux 5.14)"
+.\" commit 0ae71c7720e3ae3aabd2e8a072d27f7bd173d25c
+Perform the equivalent of
+.B SECCOMP_IOCTL_NOTIF_ADDFD
+plus
+.B SECCOMP_IOCTL_NOTIF_SEND
+as an atomic operation.
+On successful invocation, the target process's
+.I errno
+will be 0
+and the return value will be the file descriptor number
+that was allocated in the target.
+If allocating the file descriptor in the target fails,
+the target's system call continues to be blocked
+until a successful response is sent.
+.RE
+.TP
+.I srcfd
+This field should be set to the number of the file descriptor
+in the supervisor that is to be duplicated.
+.TP
+.I newfd
+This field determines which file descriptor number is allocated in the target.
+If the
+.B SECCOMP_ADDFD_FLAG_SETFD
+flag is set,
+then this field specifies which file descriptor number should be allocated.
+If this file descriptor number is already open in the target,
+it is atomically closed and reused.
+If the descriptor duplication fails due to an LSM check, or if
+.I srcfd
+is not a valid file descriptor,
+the file descriptor
+.I newfd
+will not be closed in the target process.
+.IP
+If the
+.B SECCOMP_ADDFD_FLAG_SETFD
+flag it not set, then this field must be 0,
+and the kernel allocates the lowest unused file descriptor number
+in the target.
+.TP
+.I newfd_flags
+This field is a bit mask specifying flags that should be set on
+the file descriptor that is received in the target process.
+Currently, only the following flag is implemented:
+.RS
+.TP
+.B O_CLOEXEC
+Set the close-on-exec flag on the received file descriptor.
+.RE
+.P
+On success, this
+.BR ioctl (2)
+call returns the number of the file descriptor that was allocated
+in the target.
+Assuming that the emulated system call is one that returns
+a file descriptor as its function result (e.g.,
+.BR socket (2)),
+this value can be used as the return value
+.RI ( resp.val )
+that is supplied in the response that is subsequently sent with the
+.B SECCOMP_IOCTL_NOTIF_SEND
+operation.
+.P
+On error, \-1 is returned and
+.I errno
+is set to indicate the cause of the error.
+.P
+This operation can fail with the following errors:
+.TP
+.B EBADF
+Allocating the file descriptor in the target would cause the target's
+.B RLIMIT_NOFILE
+limit to be exceeded (see
+.BR getrlimit (2)).
+.TP
+.B EBUSY
+If the flag
+.B SECCOMP_IOCTL_NOTIF_SEND
+is used, this means the operation can't proceed until other
+.B SECCOMP_IOCTL_NOTIF_ADDFD
+requests are processed.
+.TP
+.B EINPROGRESS
+The user-space notification specified in the
+.I id
+field exists but has not yet been fetched (by a
+.BR SECCOMP_IOCTL_NOTIF_RECV )
+or has already been responded to (by a
+.BR SECCOMP_IOCTL_NOTIF_SEND ).
+.TP
+.B EINVAL
+An invalid flag was specified in the
+.I flags
+or
+.I newfd_flags
+field, or the
+.I newfd
+field is nonzero and the
+.B SECCOMP_ADDFD_FLAG_SETFD
+flag was not specified in the
+.I flags
+field.
+.TP
+.B EMFILE
+The file descriptor number specified in
+.I newfd
+exceeds the limit specified in
+.IR /proc/sys/fs/nr_open .
+.TP
+.B ENOENT
+The blocked system call in the target
+has been interrupted by a signal handler
+or the target has terminated.
+.P
+Here is some sample code (with error handling omitted) that uses the
+.B SECCOMP_ADDFD_FLAG_SETFD
+operation (here, to emulate a call to
+.BR openat (2)):
+.P
+.EX
+.in +4n
+int fd, removeFd;
+\&
+fd = openat(req\->data.args[0], path, req\->data.args[2],
+                req\->data.args[3]);
+\&
+struct seccomp_notif_addfd addfd;
+addfd.id = req\->id; /* Cookie from SECCOMP_IOCTL_NOTIF_RECV */
+addfd.srcfd = fd;
+addfd.newfd = 0;
+addfd.flags = 0;
+addfd.newfd_flags = O_CLOEXEC;
+\&
+targetFd = ioctl(notifyFd, SECCOMP_IOCTL_NOTIF_ADDFD, &addfd);
+\&
+close(fd);          /* No longer needed in supervisor */
+\&
+struct seccomp_notif_resp *resp;
+    /* Code to allocate 'resp' omitted */
+resp\->id = req\->id;
+resp\->error = 0;        /* "Success" */
+resp\->val = targetFd;
+resp\->flags = 0;
+ioctl(notifyFd, SECCOMP_IOCTL_NOTIF_SEND, resp);
+.in
+.EE
+.SH NOTES
+One example use case for the user-space notification
+mechanism is to allow a container manager
+(a process which is typically running with more privilege than
+the processes inside the container)
+to mount block devices or create device nodes for the container.
+The mount use case provides an example of where the
+.B SECCOMP_USER_NOTIF_FLAG_CONTINUE
+.BR ioctl (2)
+operation is useful.
+Upon receiving a notification for the
+.BR mount (2)
+system call, the container manager (the "supervisor") can distinguish
+a request to mount a block filesystem
+(which would not be possible for a "target" process inside the container)
+and mount that file system.
+If, on the other hand, the container manager detects that the operation
+could be performed by the process inside the container
+(e.g., a mount of a
+.BR tmpfs (5)
+filesystem), it can notify the kernel that the target process's
+.BR mount (2)
+system call can continue.
+.\"
+.SS select()/poll()/epoll semantics
+The file descriptor returned when
+.BR seccomp (2)
+is employed with the
+.B SECCOMP_FILTER_FLAG_NEW_LISTENER
+flag can be monitored using
+.BR poll (2),
+.BR epoll (7),
+and
+.BR select (2).
+These interfaces indicate that the file descriptor is ready as follows:
+.IP \[bu] 3
+When a notification is pending,
+these interfaces indicate that the file descriptor is readable.
+Following such an indication, a subsequent
+.B SECCOMP_IOCTL_NOTIF_RECV
+.BR ioctl (2)
+will not block, returning either information about a notification
+or else failing with the error
+.B EINTR
+if the target has been killed by a signal or its system call
+has been interrupted by a signal handler.
+.IP \[bu]
+After the notification has been received (i.e., by the
+.B SECCOMP_IOCTL_NOTIF_RECV
+.BR ioctl (2)
+operation), these interfaces indicate that the file descriptor is writable,
+meaning that a notification response can be sent using the
+.B SECCOMP_IOCTL_NOTIF_SEND
+.BR ioctl (2)
+operation.
+.IP \[bu]
+After the last thread using the filter has terminated and been reaped using
+.BR waitpid (2)
+(or similar),
+the file descriptor indicates an end-of-file condition (readable in
+.BR select (2);
+.BR POLLHUP / EPOLLHUP
+in
+.BR poll (2)/
+.BR epoll_wait (2)).
+.SS Design goals; use of SECCOMP_USER_NOTIF_FLAG_CONTINUE
+The intent of the user-space notification feature is
+to allow system calls to be performed on behalf of the target.
+The target's system call should either be handled by the supervisor or
+allowed to continue normally in the kernel (where standard security
+policies will be applied).
+.P
+.BR "Note well" :
+this mechanism must not be used to make security policy decisions
+about the system call,
+which would be inherently race-prone for reasons described next.
+.P
+The
+.B SECCOMP_USER_NOTIF_FLAG_CONTINUE
+flag must be used with caution.
+If set by the supervisor, the target's system call will continue.
+However, there is a time-of-check, time-of-use race here,
+since an attacker could exploit the interval of time where the target is
+blocked waiting on the "continue" response to do things such as
+rewriting the system call arguments.
+.P
+Note furthermore that a user-space notifier can be bypassed if
+the existing filters allow the use of
+.BR seccomp (2)
+or
+.BR prctl (2)
+to install a filter that returns an action value with a higher precedence than
+.B SECCOMP_RET_USER_NOTIF
+(see
+.BR seccomp (2)).
+.P
+It should thus be absolutely clear that the
+seccomp user-space notification mechanism
+.B can not
+be used to implement a security policy!
+It should only ever be used in scenarios where a more privileged process
+supervises the system calls of a lesser privileged target to
+get around kernel-enforced security restrictions when
+the supervisor deems this safe.
+In other words,
+in order to continue a system call, the supervisor should be sure that
+another security mechanism or the kernel itself will sufficiently block
+the system call if its arguments are rewritten to something unsafe.
+.\"
+.SS Caveats regarding the use of \fI/proc/\fPtid\fI/mem\fP
+The discussion above noted the need to use the
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+.BR ioctl (2)
+when opening the
+.IR /proc/ tid /mem
+file of the target
+to avoid the possibility of accessing the memory of the wrong process
+in the event that the target terminates and its ID
+is recycled by another (unrelated) thread.
+However, the use of this
+.BR ioctl (2)
+operation is also necessary in other situations,
+as explained in the following paragraphs.
+.P
+Consider the following scenario, where the supervisor
+tries to read the pathname argument of a target's blocked
+.BR mount (2)
+system call:
+.IP (1) 5
+From one of its functions
+.RI ( func() ),
+the target calls
+.BR mount (2),
+which triggers a user-space notification and causes the target to block.
+.IP (2)
+The supervisor receives the notification, opens
+.IR /proc/ tid /mem ,
+and (successfully) performs the
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+check.
+.IP (3)
+The target receives a signal, which causes the
+.BR mount (2)
+to abort.
+.IP (4)
+The signal handler executes in the target, and returns.
+.IP (5)
+Upon return from the handler, the execution of
+.I func()
+resumes, and it returns (and perhaps other functions are called,
+overwriting the memory that had been used for the stack frame of
+.IR func() ).
+.IP (6)
+Using the address provided in the notification information,
+the supervisor reads from the target's memory location that used to
+contain the pathname.
+.IP (7)
+The supervisor now calls
+.BR mount (2)
+with some arbitrary bytes obtained in the previous step.
+.P
+The conclusion from the above scenario is this:
+since the target's blocked system call may be interrupted by a signal handler,
+the supervisor must be written to expect that the
+target may abandon its system call at
+.B any
+time;
+in such an event, any information that the supervisor obtained from
+the target's memory must be considered invalid.
+.P
+To prevent such scenarios,
+every read from the target's memory must be separated from use of
+the bytes so obtained by a
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+check.
+In the above example, the check would be placed between the two final steps.
+An example of such a check is shown in EXAMPLES.
+.P
+Following on from the above, it should be clear that
+a write by the supervisor into the target's memory can
+.B never
+be considered safe.
+.\"
+.SS Caveats regarding blocking system calls
+Suppose that the target performs a blocking system call (e.g.,
+.BR accept (2))
+that the supervisor should handle.
+The supervisor might then in turn execute the same blocking system call.
+.P
+In this scenario,
+it is important to note that if the target's system call is now
+interrupted by a signal, the supervisor is
+.I not
+informed of this.
+If the supervisor does not take suitable steps to
+actively discover that the target's system call has been canceled,
+various difficulties can occur.
+Taking the example of
+.BR accept (2),
+the supervisor might remain blocked in its
+.BR accept (2)
+holding a port number that the target
+(which, after the interruption by the signal handler,
+perhaps closed  its listening socket) might expect to be able to reuse in a
+.BR bind (2)
+call.
+.P
+Therefore, when the supervisor wishes to emulate a blocking system call,
+it must do so in such a way that it gets informed if the target's
+system call is interrupted by a signal handler.
+For example, if the supervisor itself executes the same
+blocking system call, then it could employ a separate thread
+that uses the
+.B SECCOMP_IOCTL_NOTIF_ID_VALID
+operation to check if the target is still blocked in its system call.
+Alternatively, in the
+.BR accept (2)
+example, the supervisor might use
+.BR poll (2)
+to monitor both the notification file descriptor
+(so as to discover when the target's
+.BR accept (2)
+call has been interrupted) and the listening file descriptor
+(so as to know when a connection is available).
+.P
+If the target's system call is interrupted,
+the supervisor must take care to release resources (e.g., file descriptors)
+that it acquired on behalf of the target.
+.\"
+.SS Interaction with SA_RESTART signal handlers
+Consider the following scenario:
+.IP (1) 5
+The target process has used
+.BR sigaction (2)
+to install a signal handler with the
+.B SA_RESTART
+flag.
+.IP (2)
+The target has made a system call that triggered a seccomp
+user-space notification and the target is currently blocked
+until the supervisor sends a notification response.
+.IP (3)
+A signal is delivered to the target and the signal handler is executed.
+.IP (4)
+When (if) the supervisor attempts to send a notification response, the
+.B SECCOMP_IOCTL_NOTIF_SEND
+.BR ioctl (2))
+operation will fail with the
+.B ENOENT
+error.
+.P
+In this scenario, the kernel will restart the target's system call.
+Consequently, the supervisor will receive another user-space notification.
+Thus, depending on how many times the blocked system call
+is interrupted by a signal handler,
+the supervisor may receive multiple notifications for
+the same instance of a system call in the target.
+.P
+One oddity is that system call restarting as described in this scenario
+will occur even for the blocking system calls listed in
+.BR signal (7)
+that would
+.B never
+normally be restarted by the
+.B SA_RESTART
+flag.
+.\" FIXME
+.\" About the above, Kees Cook commented:
+.\"
+.\" Does this need fixing? I imagine the correct behavior for this case
+.\" would be a response to _SEND of EINPROGRESS and the target would see
+.\" EINTR normally?
+.\"
+.\" I mean, it's not like seccomp doesn't already expose weirdness with
+.\" syscall restarts. Not even arm64 compat agrees[3] with arm32 in this
+.\" regard. :(
+.
+.\" FIXME
+.\" Michael Kerrisk:
+.\" I wonder about the effect of this oddity for system calls that
+.\" are normally nonrestartable because they have timeouts. My
+.\" understanding is that the kernel doesn't restart those system
+.\" calls because it's impossible for the kernel to restart the call
+.\" with the right timeout value. I wonder what happens when those
+.\" system calls are restarted in the scenario we're discussing.)
+.P
+Furthermore, if the supervisor response is a file descriptor
+added with
+.BR SECCOMP_IOCTL_NOTIF_ADDFD ,
+then the flag
+.B SECCOMP_ADDFD_FLAG_SEND
+can be used to atomically add the file descriptor and return that value,
+making sure no file descriptors are inadvertently leaked into the target.
+.SH BUGS
+If a
+.B SECCOMP_IOCTL_NOTIF_RECV
+.BR ioctl (2)
+operation
+.\" or a poll/epoll/select
+is performed after the target terminates, then the
+.BR ioctl (2)
+call simply blocks (rather than returning an error to indicate that the
+target no longer exists).
+.\" FIXME
+.\" Comment from Kees Cook:
+.\"
+.\" I want this fixed. It caused me no end of pain when building the
+.\" selftests, and ended up spawning my implementing a global test timeout
+.\" in kselftest. :P Before the usage counter refactor, there was no sane
+.\" way to deal with this, but now I think we're close.
+.\"
+.SH EXAMPLES
+The (somewhat contrived) program shown below demonstrates the use of
+the interfaces described in this page.
+The program creates a child process that serves as the "target" process.
+The child process installs a seccomp filter that returns the
+.B SECCOMP_RET_USER_NOTIF
+action value if a call is made to
+.BR mkdir (2).
+The child process then calls
+.BR mkdir (2)
+once for each of the supplied command-line arguments,
+and reports the result returned by the call.
+After processing all arguments, the child process terminates.
+.P
+The parent process acts as the supervisor, listening for the notifications
+that are generated when the target process calls
+.BR mkdir (2).
+When such a notification occurs,
+the supervisor examines the memory of the target process (using
+.IR /proc/ pid /mem )
+to discover the pathname argument that was supplied to the
+.BR mkdir (2)
+call, and performs one of the following actions:
+.IP \[bu] 3
+If the pathname begins with the prefix "/tmp/",
+then the supervisor attempts to create the specified directory,
+and then spoofs a return for the target process based on the return
+value of the supervisor's
+.BR mkdir (2)
+call.
+In the event that that call succeeds,
+the spoofed success return value is the length of the pathname.
+.IP \[bu]
+If the pathname begins with "./" (i.e., it is a relative pathname),
+the supervisor sends a
+.B SECCOMP_USER_NOTIF_FLAG_CONTINUE
+response to the kernel to say that the kernel should execute
+the target process's
+.BR mkdir (2)
+call.
+.IP \[bu]
+If the pathname begins with some other prefix,
+the supervisor spoofs an error return for the target process,
+so that the target process's
+.BR mkdir (2)
+call appears to fail with the error
+.B EOPNOTSUPP
+("Operation not supported").
+Additionally, if the specified pathname is exactly "/bye",
+then the supervisor terminates.
+.P
+This program can be used to demonstrate various aspects of the
+behavior of the seccomp user-space notification mechanism.
+To help aid such demonstrations,
+the program logs various messages to show the operation
+of the target process (lines prefixed "T:") and the supervisor
+(indented lines prefixed "S:").
+.P
+In the following example, the target attempts to create the directory
+.IR /tmp/x .
+Upon receiving the notification, the supervisor creates the directory on the
+target's behalf,
+and spoofs a success return to be received by the target process's
+.BR mkdir (2)
+call.
+.P
+.in +4n
+.EX
+$ \fB./seccomp_unotify /tmp/x\fP
+T: PID = 23168
+\&
+T: about to mkdir("/tmp/x")
+        S: got notification (ID 0x17445c4a0f4e0e3c) for PID 23168
+        S: executing: mkdir("/tmp/x", 0700)
+        S: success! spoofed return = 6
+        S: sending response (flags = 0; val = 6; error = 0)
+T: SUCCESS: mkdir(2) returned 6
+\&
+T: terminating
+        S: target has terminated; bye
+.EE
+.in
+.P
+In the above output, note that the spoofed return value seen by the target
+process is 6 (the length of the pathname
+.IR /tmp/x ),
+whereas a normal
+.BR mkdir (2)
+call returns 0 on success.
+.P
+In the next example, the target attempts to create a directory using the
+relative pathname
+.IR ./sub .
+Since this pathname starts with "./",
+the supervisor sends a
+.B SECCOMP_USER_NOTIF_FLAG_CONTINUE
+response to the kernel,
+and the kernel then (successfully) executes the target process's
+.BR mkdir (2)
+call.
+.P
+.in +4n
+.EX
+$ \fB./seccomp_unotify ./sub\fP
+T: PID = 23204
+\&
+T: about to mkdir("./sub")
+        S: got notification (ID 0xddb16abe25b4c12) for PID 23204
+        S: target can execute system call
+        S: sending response (flags = 0x1; val = 0; error = 0)
+T: SUCCESS: mkdir(2) returned 0
+\&
+T: terminating
+        S: target has terminated; bye
+.EE
+.in
+.P
+If the target process attempts to create a directory with
+a pathname that doesn't start with "." and doesn't begin with the prefix
+"/tmp/", then the supervisor spoofs an error return
+.RB ( EOPNOTSUPP ,
+"Operation not  supported")
+for the target's
+.BR mkdir (2)
+call (which is not executed):
+.P
+.in +4n
+.EX
+$ \fB./seccomp_unotify /xxx\fP
+T: PID = 23178
+\&
+T: about to mkdir("/xxx")
+        S: got notification (ID 0xe7dc095d1c524e80) for PID 23178
+        S: spoofing error response (Operation not supported)
+        S: sending response (flags = 0; val = 0; error = \-95)
+T: ERROR: mkdir(2): Operation not supported
+\&
+T: terminating
+        S: target has terminated; bye
+.EE
+.in
+.P
+In the next example,
+the target process attempts to create a directory with the pathname
+.BR /tmp/nosuchdir/b .
+Upon receiving the notification,
+the supervisor attempts to create that directory, but the
+.BR mkdir (2)
+call fails because the directory
+.B /tmp/nosuchdir
+does not exist.
+Consequently, the supervisor spoofs an error return that passes the error
+that it received back to the target process's
+.BR mkdir (2)
+call.
+.P
+.in +4n
+.EX
+$ \fB./seccomp_unotify /tmp/nosuchdir/b\fP
+T: PID = 23199
+\&
+T: about to mkdir("/tmp/nosuchdir/b")
+        S: got notification (ID 0x8744454293506046) for PID 23199
+        S: executing: mkdir("/tmp/nosuchdir/b", 0700)
+        S: failure! (errno = 2; No such file or directory)
+        S: sending response (flags = 0; val = 0; error = \-2)
+T: ERROR: mkdir(2): No such file or directory
+\&
+T: terminating
+        S: target has terminated; bye
+.EE
+.in
+.P
+If the supervisor receives a notification and sees that the
+argument of the target's
+.BR mkdir (2)
+is the string "/bye", then (as well as spoofing an
+.B EOPNOTSUPP
+error), the supervisor terminates.
+If the target process subsequently executes another
+.BR mkdir (2)
+that triggers its seccomp filter to return the
+.B SECCOMP_RET_USER_NOTIF
+action value, then the kernel causes the target process's system call to
+fail with the error
+.B ENOSYS
+("Function not implemented").
+This is demonstrated by the following example:
+.P
+.in +4n
+.EX
+$ \fB./seccomp_unotify /bye /tmp/y\fP
+T: PID = 23185
+\&
+T: about to mkdir("/bye")
+        S: got notification (ID 0xa81236b1d2f7b0f4) for PID 23185
+        S: spoofing error response (Operation not supported)
+        S: sending response (flags = 0; val = 0; error = \-95)
+        S: terminating **********
+T: ERROR: mkdir(2): Operation not supported
+\&
+T: about to mkdir("/tmp/y")
+T: ERROR: mkdir(2): Function not implemented
+\&
+T: terminating
+.EE
+.in
+.\"
+.SS Program source
+.\" SRC BEGIN (seccomp_unotify.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <linux/audit.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/prctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+\&
+#define ARRAY_SIZE(arr)  (sizeof(arr) / sizeof((arr)[0]))
+\&
+/* Send the file descriptor \[aq]fd\[aq] over the connected UNIX domain socket
+   \[aq]sockfd\[aq]. Returns 0 on success, or \-1 on error. */
+\&
+static int
+sendfd(int sockfd, int fd)
+{
+    int             data;
+    struct iovec    iov;
+    struct msghdr   msgh;
+    struct cmsghdr  *cmsgp;
+\&
+    /* Allocate a char array of suitable size to hold the ancillary data.
+       However, since this buffer is in reality a \[aq]struct cmsghdr\[aq], use a
+       union to ensure that it is suitably aligned. */
+    union {
+        char   buf[CMSG_SPACE(sizeof(int))];
+                        /* Space large enough to hold an \[aq]int\[aq] */
+        struct cmsghdr align;
+    } controlMsg;
+\&
+    /* The \[aq]msg_name\[aq] field can be used to specify the address of the
+       destination socket when sending a datagram. However, we do not
+       need to use this field because \[aq]sockfd\[aq] is a connected socket. */
+\&
+    msgh.msg_name = NULL;
+    msgh.msg_namelen = 0;
+\&
+    /* On Linux, we must transmit at least one byte of real data in
+       order to send ancillary data. We transmit an arbitrary integer
+       whose value is ignored by recvfd(). */
+\&
+    msgh.msg_iov = &iov;
+    msgh.msg_iovlen = 1;
+    iov.iov_base = &data;
+    iov.iov_len = sizeof(int);
+    data = 12345;
+\&
+    /* Set \[aq]msghdr\[aq] fields that describe ancillary data */
+\&
+    msgh.msg_control = controlMsg.buf;
+    msgh.msg_controllen = sizeof(controlMsg.buf);
+\&
+    /* Set up ancillary data describing file descriptor to send */
+\&
+    cmsgp = CMSG_FIRSTHDR(&msgh);
+    cmsgp\->cmsg_level = SOL_SOCKET;
+    cmsgp\->cmsg_type = SCM_RIGHTS;
+    cmsgp\->cmsg_len = CMSG_LEN(sizeof(int));
+    memcpy(CMSG_DATA(cmsgp), &fd, sizeof(int));
+\&
+    /* Send real plus ancillary data */
+\&
+    if (sendmsg(sockfd, &msgh, 0) == \-1)
+        return \-1;
+\&
+    return 0;
+}
+\&
+/* Receive a file descriptor on a connected UNIX domain socket. Returns
+   the received file descriptor on success, or \-1 on error. */
+\&
+static int
+recvfd(int sockfd)
+{
+    int            data, fd;
+    ssize_t        nr;
+    struct iovec   iov;
+    struct msghdr  msgh;
+\&
+    /* Allocate a char buffer for the ancillary data. See the comments
+       in sendfd() */
+    union {
+        char   buf[CMSG_SPACE(sizeof(int))];
+        struct cmsghdr align;
+    } controlMsg;
+    struct cmsghdr *cmsgp;
+\&
+    /* The \[aq]msg_name\[aq] field can be used to obtain the address of the
+       sending socket. However, we do not need this information. */
+\&
+    msgh.msg_name = NULL;
+    msgh.msg_namelen = 0;
+\&
+    /* Specify buffer for receiving real data */
+\&
+    msgh.msg_iov = &iov;
+    msgh.msg_iovlen = 1;
+    iov.iov_base = &data;       /* Real data is an \[aq]int\[aq] */
+    iov.iov_len = sizeof(int);
+\&
+    /* Set \[aq]msghdr\[aq] fields that describe ancillary data */
+\&
+    msgh.msg_control = controlMsg.buf;
+    msgh.msg_controllen = sizeof(controlMsg.buf);
+\&
+    /* Receive real plus ancillary data; real data is ignored */
+\&
+    nr = recvmsg(sockfd, &msgh, 0);
+    if (nr == \-1)
+        return \-1;
+\&
+    cmsgp = CMSG_FIRSTHDR(&msgh);
+\&
+    /* Check the validity of the \[aq]cmsghdr\[aq] */
+\&
+    if (cmsgp == NULL
+        || cmsgp\->cmsg_len != CMSG_LEN(sizeof(int))
+        || cmsgp\->cmsg_level != SOL_SOCKET
+        || cmsgp\->cmsg_type != SCM_RIGHTS)
+    {
+        errno = EINVAL;
+        return \-1;
+    }
+\&
+    /* Return the received file descriptor to our caller */
+\&
+    memcpy(&fd, CMSG_DATA(cmsgp), sizeof(int));
+    return fd;
+}
+\&
+static void
+sigchldHandler(int sig)
+{
+    char msg[] = "\etS: target has terminated; bye\en";
+\&
+    write(STDOUT_FILENO, msg, sizeof(msg) \- 1);
+    _exit(EXIT_SUCCESS);
+}
+\&
+static int
+seccomp(unsigned int operation, unsigned int flags, void *args)
+{
+    return syscall(SYS_seccomp, operation, flags, args);
+}
+\&
+/* The following is the x86\-64\-specific BPF boilerplate code for checking
+   that the BPF program is running on the right architecture + ABI. At
+   completion of these instructions, the accumulator contains the system
+   call number. */
+\&
+/* For the x32 ABI, all system call numbers have bit 30 set */
+\&
+#define X32_SYSCALL_BIT         0x40000000
+\&
+#define X86_64_CHECK_ARCH_AND_LOAD_SYSCALL_NR \e
+        BPF_STMT(BPF_LD | BPF_W | BPF_ABS, \e
+                 (offsetof(struct seccomp_data, arch))), \e
+        BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, AUDIT_ARCH_X86_64, 0, 2), \e
+        BPF_STMT(BPF_LD | BPF_W | BPF_ABS, \e
+                 (offsetof(struct seccomp_data, nr))), \e
+        BPF_JUMP(BPF_JMP | BPF_JGE | BPF_K, X32_SYSCALL_BIT, 0, 1), \e
+        BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_KILL_PROCESS)
+\&
+/* installNotifyFilter() installs a seccomp filter that generates
+   user\-space notifications (SECCOMP_RET_USER_NOTIF) when the process
+   calls mkdir(2); the filter allows all other system calls.
+\&
+   The function return value is a file descriptor from which the
+   user\-space notifications can be fetched. */
+\&
+static int
+installNotifyFilter(void)
+{
+    int notifyFd;
+\&
+    struct sock_filter filter[] = {
+        X86_64_CHECK_ARCH_AND_LOAD_SYSCALL_NR,
+\&
+        /* mkdir() triggers notification to user\-space supervisor */
+\&
+        BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, SYS_mkdir, 0, 1),
+        BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_USER_NOTIF),
+\&
+        /* Every other system call is allowed */
+\&
+        BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
+    };
+\&
+    struct sock_fprog prog = {
+        .len = ARRAY_SIZE(filter),
+        .filter = filter,
+    };
+\&
+    /* Install the filter with the SECCOMP_FILTER_FLAG_NEW_LISTENER flag;
+       as a result, seccomp() returns a notification file descriptor. */
+\&
+    notifyFd = seccomp(SECCOMP_SET_MODE_FILTER,
+                       SECCOMP_FILTER_FLAG_NEW_LISTENER, &prog);
+    if (notifyFd == \-1)
+        err(EXIT_FAILURE, "seccomp\-install\-notify\-filter");
+\&
+    return notifyFd;
+}
+\&
+/* Close a pair of sockets created by socketpair() */
+\&
+static void
+closeSocketPair(int sockPair[2])
+{
+    if (close(sockPair[0]) == \-1)
+        err(EXIT_FAILURE, "closeSocketPair\-close\-0");
+    if (close(sockPair[1]) == \-1)
+        err(EXIT_FAILURE, "closeSocketPair\-close\-1");
+}
+\&
+/* Implementation of the target process; create a child process that:
+\&
+   (1) installs a seccomp filter with the
+       SECCOMP_FILTER_FLAG_NEW_LISTENER flag;
+   (2) writes the seccomp notification file descriptor returned from
+       the previous step onto the UNIX domain socket, \[aq]sockPair[0]\[aq];
+   (3) calls mkdir(2) for each element of \[aq]argv\[aq].
+\&
+   The function return value in the parent is the PID of the child
+   process; the child does not return from this function. */
+\&
+static pid_t
+targetProcess(int sockPair[2], char *argv[])
+{
+    int    notifyFd, s;
+    pid_t  targetPid;
+\&
+    targetPid = fork();
+\&
+    if (targetPid == \-1)
+        err(EXIT_FAILURE, "fork");
+\&
+    if (targetPid > 0)          /* In parent, return PID of child */
+        return targetPid;
+\&
+    /* Child falls through to here */
+\&
+    printf("T: PID = %ld\en", (long) getpid());
+\&
+    /* Install seccomp filter(s) */
+\&
+    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
+        err(EXIT_FAILURE, "prctl");
+\&
+    notifyFd = installNotifyFilter();
+\&
+    /* Pass the notification file descriptor to the tracing process over
+       a UNIX domain socket */
+\&
+    if (sendfd(sockPair[0], notifyFd) == \-1)
+        err(EXIT_FAILURE, "sendfd");
+\&
+    /* Notification and socket FDs are no longer needed in target */
+\&
+    if (close(notifyFd) == \-1)
+        err(EXIT_FAILURE, "close\-target\-notify\-fd");
+\&
+    closeSocketPair(sockPair);
+\&
+    /* Perform a mkdir() call for each of the command\-line arguments */
+\&
+    for (char **ap = argv; *ap != NULL; ap++) {
+        printf("\enT: about to mkdir(\e"%s\e")\en", *ap);
+\&
+        s = mkdir(*ap, 0700);
+        if (s == \-1)
+            perror("T: ERROR: mkdir(2)");
+        else
+            printf("T: SUCCESS: mkdir(2) returned %d\en", s);
+    }
+\&
+    printf("\enT: terminating\en");
+    exit(EXIT_SUCCESS);
+}
+\&
+/* Check that the notification ID provided by a SECCOMP_IOCTL_NOTIF_RECV
+   operation is still valid. It will no longer be valid if the target
+   process has terminated or is no longer blocked in the system call that
+   generated the notification (because it was interrupted by a signal).
+\&
+   This operation can be used when doing such things as accessing
+   /proc/PID files in the target process in order to avoid TOCTOU race
+   conditions where the PID that is returned by SECCOMP_IOCTL_NOTIF_RECV
+   terminates and is reused by another process. */
+\&
+static bool
+cookieIsValid(int notifyFd, uint64_t id)
+{
+    return ioctl(notifyFd, SECCOMP_IOCTL_NOTIF_ID_VALID, &id) == 0;
+}
+\&
+/* Access the memory of the target process in order to fetch the
+   pathname referred to by the system call argument \[aq]argNum\[aq] in
+   \[aq]req\->data.args[]\[aq].  The pathname is returned in \[aq]path\[aq],
+   a buffer of \[aq]len\[aq] bytes allocated by the caller.
+\&
+   Returns true if the pathname is successfully fetched, and false
+   otherwise. For possible causes of failure, see the comments below. */
+\&
+static bool
+getTargetPathname(struct seccomp_notif *req, int notifyFd,
+                  int argNum, char *path, size_t len)
+{
+    int      procMemFd;
+    char     procMemPath[PATH_MAX];
+    ssize_t  nread;
+\&
+    snprintf(procMemPath, sizeof(procMemPath), "/proc/%d/mem", req\->pid);
+\&
+    procMemFd = open(procMemPath, O_RDONLY | O_CLOEXEC);
+    if (procMemFd == \-1)
+        return false;
+\&
+    /* Check that the process whose info we are accessing is still alive
+       and blocked in the system call that caused the notification.
+       If the SECCOMP_IOCTL_NOTIF_ID_VALID operation (performed in
+       cookieIsValid()) succeeded, we know that the /proc/PID/mem file
+       descriptor that we opened corresponded to the process for which we
+       received a notification. If that process subsequently terminates,
+       then read() on that file descriptor will return 0 (EOF). */
+\&
+    if (!cookieIsValid(notifyFd, req\->id)) {
+        close(procMemFd);
+        return false;
+    }
+\&
+    /* Read bytes at the location containing the pathname argument */
+\&
+    nread = pread(procMemFd, path, len, req\->data.args[argNum]);
+\&
+    close(procMemFd);
+\&
+    if (nread <= 0)
+        return false;
+\&
+    /* Once again check that the notification ID is still valid. The
+       case we are particularly concerned about here is that just
+       before we fetched the pathname, the target\[aq]s blocked system
+       call was interrupted by a signal handler, and after the handler
+       returned, the target carried on execution (past the interrupted
+       system call). In that case, we have no guarantees about what we
+       are reading, since the target\[aq]s memory may have been arbitrarily
+       changed by subsequent operations. */
+\&
+    if (!cookieIsValid(notifyFd, req\->id)) {
+        perror("\etS: notification ID check failed!!!");
+        return false;
+    }
+\&
+    /* Even if the target\[aq]s system call was not interrupted by a signal,
+       we have no guarantees about what was in the memory of the target
+       process. (The memory may have been modified by another thread, or
+       even by an external attacking process.) We therefore treat the
+       buffer returned by pread() as untrusted input. The buffer should
+       contain a terminating null byte; if not, then we will trigger an
+       error for the target process. */
+\&
+    if (strnlen(path, nread) < nread)
+        return true;
+\&
+    return false;
+}
+\&
+/* Allocate buffers for the seccomp user\-space notification request and
+   response structures. It is the caller\[aq]s responsibility to free the
+   buffers returned via \[aq]req\[aq] and \[aq]resp\[aq]. */
+\&
+static void
+allocSeccompNotifBuffers(struct seccomp_notif **req,
+                         struct seccomp_notif_resp **resp,
+                         struct seccomp_notif_sizes *sizes)
+{
+    size_t  resp_size;
+\&
+    /* Discover the sizes of the structures that are used to receive
+       notifications and send notification responses, and allocate
+       buffers of those sizes. */
+\&
+    if (seccomp(SECCOMP_GET_NOTIF_SIZES, 0, sizes) == \-1)
+        err(EXIT_FAILURE, "seccomp\-SECCOMP_GET_NOTIF_SIZES");
+\&
+    *req = malloc(sizes\->seccomp_notif);
+    if (*req == NULL)
+        err(EXIT_FAILURE, "malloc\-seccomp_notif");
+\&
+    /* When allocating the response buffer, we must allow for the fact
+       that the user\-space binary may have been built with user\-space
+       headers where \[aq]struct seccomp_notif_resp\[aq] is bigger than the
+       response buffer expected by the (older) kernel. Therefore, we
+       allocate a buffer that is the maximum of the two sizes. This
+       ensures that if the supervisor places bytes into the response
+       structure that are past the response size that the kernel expects,
+       then the supervisor is not touching an invalid memory location. */
+\&
+    resp_size = sizes\->seccomp_notif_resp;
+    if (sizeof(struct seccomp_notif_resp) > resp_size)
+        resp_size = sizeof(struct seccomp_notif_resp);
+\&
+    *resp = malloc(resp_size);
+    if (*resp == NULL)
+        err(EXIT_FAILURE, "malloc\-seccomp_notif_resp");
+\&
+}
+\&
+/* Handle notifications that arrive via the SECCOMP_RET_USER_NOTIF file
+   descriptor, \[aq]notifyFd\[aq]. */
+\&
+static void
+handleNotifications(int notifyFd)
+{
+    bool                        pathOK;
+    char                        path[PATH_MAX];
+    struct seccomp_notif        *req;
+    struct seccomp_notif_resp   *resp;
+    struct seccomp_notif_sizes  sizes;
+\&
+    allocSeccompNotifBuffers(&req, &resp, &sizes);
+\&
+    /* Loop handling notifications */
+\&
+    for (;;) {
+\&
+        /* Wait for next notification, returning info in \[aq]*req\[aq] */
+\&
+        memset(req, 0, sizes.seccomp_notif);
+        if (ioctl(notifyFd, SECCOMP_IOCTL_NOTIF_RECV, req) == \-1) {
+            if (errno == EINTR)
+                continue;
+            err(EXIT_FAILURE, "\etS: ioctl\-SECCOMP_IOCTL_NOTIF_RECV");
+        }
+\&
+        printf("\etS: got notification (ID %#llx) for PID %d\en",
+               req\->id, req\->pid);
+\&
+        /* The only system call that can generate a notification event
+           is mkdir(2). Nevertheless, we check that the notified system
+           call is indeed mkdir() as kind of future\-proofing of this
+           code in case the seccomp filter is later modified to
+           generate notifications for other system calls. */
+\&
+        if (req\->data.nr != SYS_mkdir) {
+            printf("\etS: notification contained unexpected "
+                   "system call number; bye!!!\en");
+            exit(EXIT_FAILURE);
+        }
+\&
+        pathOK = getTargetPathname(req, notifyFd, 0, path, sizeof(path));
+\&
+        /* Prepopulate some fields of the response */
+\&
+        resp\->id = req\->id;     /* Response includes notification ID */
+        resp\->flags = 0;
+        resp\->val = 0;
+\&
+        /* If getTargetPathname() failed, trigger an EINVAL error
+           response (sending this response may yield an error if the
+           failure occurred because the notification ID was no longer
+           valid); if the directory is in /tmp, then create it on behalf
+           of the supervisor; if the pathname starts with \[aq].\[aq], tell the
+           kernel to let the target process execute the mkdir();
+           otherwise, give an error for a directory pathname in any other
+           location. */
+\&
+        if (!pathOK) {
+            resp\->error = \-EINVAL;
+            printf("\etS: spoofing error for invalid pathname (%s)\en",
+                   strerror(\-resp\->error));
+        } else if (strncmp(path, "/tmp/", strlen("/tmp/")) == 0) {
+            printf("\etS: executing: mkdir(\e"%s\e", %#llo)\en",
+                   path, req\->data.args[1]);
+\&
+            if (mkdir(path, req\->data.args[1]) == 0) {
+                resp\->error = 0;            /* "Success" */
+                resp\->val = strlen(path);   /* Used as return value of
+                                               mkdir() in target */
+                printf("\etS: success! spoofed return = %lld\en",
+                       resp\->val);
+            } else {
+\&
+                /* If mkdir() failed in the supervisor, pass the error
+                   back to the target */
+\&
+                resp\->error = \-errno;
+                printf("\etS: failure! (errno = %d; %s)\en", errno,
+                       strerror(errno));
+            }
+        } else if (strncmp(path, "./", strlen("./")) == 0) {
+            resp\->error = resp\->val = 0;
+            resp\->flags = SECCOMP_USER_NOTIF_FLAG_CONTINUE;
+            printf("\etS: target can execute system call\en");
+        } else {
+            resp\->error = \-EOPNOTSUPP;
+            printf("\etS: spoofing error response (%s)\en",
+                   strerror(\-resp\->error));
+        }
+\&
+        /* Send a response to the notification */
+\&
+        printf("\etS: sending response "
+               "(flags = %#x; val = %lld; error = %d)\en",
+               resp\->flags, resp\->val, resp\->error);
+\&
+        if (ioctl(notifyFd, SECCOMP_IOCTL_NOTIF_SEND, resp) == \-1) {
+            if (errno == ENOENT)
+                printf("\etS: response failed with ENOENT; "
+                       "perhaps target process\[aq]s syscall was "
+                       "interrupted by a signal?\en");
+            else
+                perror("ioctl\-SECCOMP_IOCTL_NOTIF_SEND");
+        }
+\&
+        /* If the pathname is just "/bye", then the supervisor breaks out
+           of the loop and terminates. This allows us to see what happens
+           if the target process makes further calls to mkdir(2). */
+\&
+        if (strcmp(path, "/bye") == 0)
+            break;
+    }
+\&
+    free(req);
+    free(resp);
+    printf("\etS: terminating **********\en");
+    exit(EXIT_FAILURE);
+}
+\&
+/* Implementation of the supervisor process:
+\&
+   (1) obtains the notification file descriptor from \[aq]sockPair[1]\[aq]
+   (2) handles notifications that arrive on that file descriptor. */
+\&
+static void
+supervisor(int sockPair[2])
+{
+    int notifyFd;
+\&
+    notifyFd = recvfd(sockPair[1]);
+\&
+    if (notifyFd == \-1)
+        err(EXIT_FAILURE, "recvfd");
+\&
+    closeSocketPair(sockPair);  /* We no longer need the socket pair */
+\&
+    handleNotifications(notifyFd);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int               sockPair[2];
+    struct sigaction  sa;
+\&
+    setbuf(stdout, NULL);
+\&
+    if (argc < 2) {
+        fprintf(stderr, "At least one pathname argument is required\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Create a UNIX domain socket that is used to pass the seccomp
+       notification file descriptor from the target process to the
+       supervisor process. */
+\&
+    if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockPair) == \-1)
+        err(EXIT_FAILURE, "socketpair");
+\&
+    /* Create a child process\-\-the "target"\-\-that installs seccomp
+       filtering. The target process writes the seccomp notification
+       file descriptor onto \[aq]sockPair[0]\[aq] and then calls mkdir(2) for
+       each directory in the command\-line arguments. */
+\&
+    (void) targetProcess(sockPair, &argv[optind]);
+\&
+    /* Catch SIGCHLD when the target terminates, so that the
+       supervisor can also terminate. */
+\&
+    sa.sa_handler = sigchldHandler;
+    sa.sa_flags = 0;
+    sigemptyset(&sa.sa_mask);
+    if (sigaction(SIGCHLD, &sa, NULL) == \-1)
+        err(EXIT_FAILURE, "sigaction");
+\&
+    supervisor(sockPair);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ioctl (2),
+.BR pidfd_getfd (2),
+.BR pidfd_open (2),
+.BR seccomp (2)
+.P
+A further example program can be found in the kernel source file
+.IR samples/seccomp/user-trap.c .
diff --git a/man/man2/security.2 b/man/man2/security.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/security.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/select.2 b/man/man2/select.2
new file mode 100644
index 000000000..bbf8ea9e0
--- /dev/null
+++ b/man/man2/select.2
@@ -0,0 +1,765 @@
+.\" This manpage is copyright (C) 1992 Drew Eckhardt,
+.\"     copyright (C) 1995 Michael Shields,
+.\"     copyright (C) 2001 Paul Sheer,
+.\"     copyright (C) 2006, 2019 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-05-18 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" Sun Feb 11 14:07:00 MET 1996  Martin Schulze  <joey@linux.de>
+.\"	* layout slightly modified
+.\"
+.\" Modified Mon Oct 21 23:05:29 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Thu Feb 24 01:41:09 CET 2000 by aeb
+.\" Modified Thu Feb  9 22:32:09 CET 2001 by bert hubert <ahu@ds9a.nl>, aeb
+.\" Modified Mon Nov 11 14:35:00 PST 2002 by Ben Woodard <ben@zork.net>
+.\" 2005-03-11, mtk, modified pselect() text (it is now a system
+.\"     call in Linux 2.6.16.
+.\"
+.TH select 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+select, pselect, FD_CLR, FD_ISSET, FD_SET, FD_ZERO, fd_set \-
+synchronous I/O multiplexing
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/select.h>
+.P
+.BR typedef " /* ... */ " fd_set;
+.P
+.BI "int select(int " nfds ", fd_set *_Nullable restrict " readfds ,
+.BI "           fd_set *_Nullable restrict " writefds ,
+.BI "           fd_set *_Nullable restrict " exceptfds ,
+.BI "           struct timeval *_Nullable restrict " timeout );
+.P
+.BI "void FD_CLR(int " fd ", fd_set *" set );
+.BI "int  FD_ISSET(int " fd ", fd_set *" set );
+.BI "void FD_SET(int " fd ", fd_set *" set );
+.BI "void FD_ZERO(fd_set *" set );
+.P
+.BI "int pselect(int " nfds ", fd_set *_Nullable restrict " readfds ,
+.BI "           fd_set *_Nullable restrict " writefds ,
+.BI "           fd_set *_Nullable restrict " exceptfds ,
+.BI "           const struct timespec *_Nullable restrict " timeout ,
+.BI "           const sigset_t *_Nullable restrict " sigmask );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pselect ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.BR "WARNING" :
+.BR select ()
+can monitor only file descriptors numbers that are less than
+.B FD_SETSIZE
+(1024)\[em]an unreasonably low limit for many modern applications\[em]and
+this limitation will not change.
+All modern applications should instead use
+.BR poll (2)
+or
+.BR epoll (7),
+which do not suffer this limitation.
+.P
+.BR select ()
+allows a program to monitor multiple file descriptors,
+waiting until one or more of the file descriptors become "ready"
+for some class of I/O operation (e.g., input possible).
+A file descriptor is considered ready if it is possible to
+perform a corresponding I/O operation (e.g.,
+.BR read (2),
+or a sufficiently small
+.BR write (2))
+without blocking.
+.\"
+.SS fd_set
+A structure type that can represent a set of file descriptors.
+According to POSIX,
+the maximum number of file descriptors in an
+.I fd_set
+structure is the value of the macro
+.BR FD_SETSIZE .
+.\"
+.SS File descriptor sets
+The principal arguments of
+.BR select ()
+are three "sets" of file descriptors (declared with the type
+.IR fd_set ),
+which allow the caller to wait for three classes of events
+on the specified set of file descriptors.
+Each of the
+.I fd_set
+arguments may be specified as NULL if no file descriptors are
+to be watched for the corresponding class of events.
+.P
+.BR "Note well" :
+Upon return, each of the file descriptor sets is modified in place
+to indicate which file descriptors are currently "ready".
+Thus, if using
+.BR select ()
+within a loop, the sets \fImust be reinitialized\fP before each call.
+.P
+The contents of a file descriptor set can be manipulated
+using the following macros:
+.TP
+.BR FD_ZERO ()
+This macro clears (removes all file descriptors from)
+.IR set .
+It should be employed as the first step in initializing a file descriptor set.
+.TP
+.BR FD_SET ()
+This macro adds the file descriptor
+.I fd
+to
+.IR set .
+Adding a file descriptor that is already present in the set is a no-op,
+and does not produce an error.
+.TP
+.BR FD_CLR ()
+This macro removes the file descriptor
+.I fd
+from
+.IR set .
+Removing a file descriptor that is not present in the set is a no-op,
+and does not produce an error.
+.TP
+.BR FD_ISSET ()
+.BR select ()
+modifies the contents of the sets according to the rules
+described below.
+After calling
+.BR select (),
+the
+.BR FD_ISSET ()
+macro
+can be used to test if a file descriptor is still present in a set.
+.BR FD_ISSET ()
+returns nonzero if the file descriptor
+.I fd
+is present in
+.IR set ,
+and zero if it is not.
+.\"
+.SS Arguments
+The arguments of
+.BR select ()
+are as follows:
+.TP
+.I readfds
+The file descriptors in this set are watched to see if they are
+ready for reading.
+A file descriptor is ready for reading if a read operation will not
+block; in particular, a file descriptor is also ready on end-of-file.
+.IP
+After
+.BR select ()
+has returned, \fIreadfds\fP will be
+cleared of all file descriptors except for those that are ready for reading.
+.TP
+.I writefds
+The file descriptors in this set are watched to see if they are
+ready for writing.
+A file descriptor is ready for writing if a write operation will not block.
+However, even if a file descriptor indicates as writable,
+a large write may still block.
+.IP
+After
+.BR select ()
+has returned, \fIwritefds\fP will be
+cleared of all file descriptors except for those that are ready for writing.
+.TP
+.I exceptfds
+The file descriptors in this set are watched for "exceptional conditions".
+For examples of some exceptional conditions, see the discussion of
+.B POLLPRI
+in
+.BR poll (2).
+.IP
+After
+.BR select ()
+has returned,
+\fIexceptfds\fP will be cleared of all file descriptors except for those
+for which an exceptional condition has occurred.
+.TP
+.I nfds
+This argument should be set to the highest-numbered file descriptor in any
+of the three sets, plus 1.
+The indicated file descriptors in each set are checked, up to this limit
+(but see BUGS).
+.TP
+.I timeout
+The
+.I timeout
+argument is a
+.I timeval
+structure (shown below) that specifies the interval that
+.BR select ()
+should block waiting for a file descriptor to become ready.
+The call will block until either:
+.RS
+.IP \[bu] 3
+a file descriptor becomes ready;
+.IP \[bu]
+the call is interrupted by a signal handler; or
+.IP \[bu]
+the timeout expires.
+.RE
+.IP
+Note that the
+.I timeout
+interval will be rounded up to the system clock granularity,
+and kernel scheduling delays mean that the blocking interval
+may overrun by a small amount.
+.IP
+If both fields of the
+.I timeval
+structure are zero, then
+.BR select ()
+returns immediately.
+(This is useful for polling.)
+.IP
+If
+.I timeout
+is specified as NULL,
+.BR select ()
+blocks indefinitely waiting for a file descriptor to become ready.
+.\"
+.SS pselect()
+The
+.BR pselect ()
+system call allows an application to safely wait until either
+a file descriptor becomes ready or until a signal is caught.
+.P
+The operation of
+.BR select ()
+and
+.BR pselect ()
+is identical, other than these three differences:
+.IP \[bu] 3
+.BR select ()
+uses a timeout that is a
+.I struct timeval
+(with seconds and microseconds), while
+.BR pselect ()
+uses a
+.I struct timespec
+(with seconds and nanoseconds).
+.IP \[bu]
+.BR select ()
+may update the
+.I timeout
+argument to indicate how much time was left.
+.BR pselect ()
+does not change this argument.
+.IP \[bu]
+.BR select ()
+has no
+.I sigmask
+argument, and behaves as
+.BR pselect ()
+called with NULL
+.IR sigmask .
+.P
+.I sigmask
+is a pointer to a signal mask (see
+.BR sigprocmask (2));
+if it is not NULL, then
+.BR pselect ()
+first replaces the current signal mask by the one pointed to by
+.IR sigmask ,
+then does the "select" function, and then restores the original
+signal mask.
+(If
+.I sigmask
+is NULL,
+the signal mask is not modified during the
+.BR pselect ()
+call.)
+.P
+Other than the difference in the precision of the
+.I timeout
+argument, the following
+.BR pselect ()
+call:
+.P
+.in +4n
+.EX
+ready = pselect(nfds, &readfds, &writefds, &exceptfds,
+                timeout, &sigmask);
+.EE
+.in
+.P
+is equivalent to
+.I atomically
+executing the following calls:
+.P
+.in +4n
+.EX
+sigset_t origmask;
+\&
+pthread_sigmask(SIG_SETMASK, &sigmask, &origmask);
+ready = select(nfds, &readfds, &writefds, &exceptfds, timeout);
+pthread_sigmask(SIG_SETMASK, &origmask, NULL);
+.EE
+.in
+.P
+The reason that
+.BR pselect ()
+is needed is that if one wants to wait for either a signal
+or for a file descriptor to become ready, then
+an atomic test is needed to prevent race conditions.
+(Suppose the signal handler sets a global flag and
+returns.
+Then a test of this global flag followed by a call of
+.BR select ()
+could hang indefinitely if the signal arrived just after the test
+but just before the call.
+By contrast,
+.BR pselect ()
+allows one to first block signals, handle the signals that have come in,
+then call
+.BR pselect ()
+with the desired
+.IR sigmask ,
+avoiding the race.)
+.SS The timeout
+The
+.I timeout
+argument for
+.BR select ()
+is a structure of the following type:
+.P
+.in +4n
+.EX
+struct timeval {
+    time_t      tv_sec;         /* seconds */
+    suseconds_t tv_usec;        /* microseconds */
+};
+.EE
+.in
+.P
+The corresponding argument for
+.BR pselect ()
+is a
+.BR timespec (3)
+structure.
+.P
+On Linux,
+.BR select ()
+modifies
+.I timeout
+to reflect the amount of time not slept; most other implementations
+do not do this.
+(POSIX.1 permits either behavior.)
+This causes problems both when Linux code which reads
+.I timeout
+is ported to other operating systems, and when code is ported to Linux
+that reuses a \fIstruct timeval\fP for multiple
+.BR select ()s
+in a loop without reinitializing it.
+Consider
+.I timeout
+to be undefined after
+.BR select ()
+returns.
+.\" .P - it is rumored that:
+.\" On BSD, when a timeout occurs, the file descriptor bits are not changed.
+.\" - it is certainly true that:
+.\" Linux follows SUSv2 and sets the bit masks to zero upon a timeout.
+.SH RETURN VALUE
+On success,
+.BR select ()
+and
+.BR pselect ()
+return the number of file descriptors contained in the three returned
+descriptor sets (that is, the total number of bits that are set in
+.IR readfds ,
+.IR writefds ,
+.IR exceptfds ).
+The return value may be zero if the timeout expired before any
+file descriptors became ready.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error;
+the file descriptor sets are unmodified,
+and
+.I timeout
+becomes undefined.
+.SH ERRORS
+.TP
+.B EBADF
+An invalid file descriptor was given in one of the sets.
+(Perhaps a file descriptor that was already closed,
+or one on which an error has occurred.)
+However, see BUGS.
+.TP
+.B EINTR
+A signal was caught; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I nfds
+is negative or exceeds the
+.B RLIMIT_NOFILE
+resource limit (see
+.BR getrlimit (2)).
+.TP
+.B EINVAL
+The value contained within
+.I timeout
+is invalid.
+.TP
+.B ENOMEM
+Unable to allocate memory for internal tables.
+.SH VERSIONS
+On some other UNIX systems,
+.\" Darwin, according to a report by Jeremy Sequoia, relayed by Josh Triplett
+.BR select ()
+can fail with the error
+.B EAGAIN
+if the system fails to allocate kernel-internal resources, rather than
+.B ENOMEM
+as Linux does.
+POSIX specifies this error for
+.BR poll (2),
+but not for
+.BR select ().
+Portable programs may wish to check for
+.B EAGAIN
+and loop, just as with
+.BR EINTR .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR select ()
+POSIX.1-2001, 4.4BSD (first appeared in 4.2BSD).
+.IP
+Generally portable to/from
+non-BSD systems supporting clones of the BSD socket layer (including
+System\ V variants).
+However, note that the System\ V variant typically
+sets the timeout variable before returning, but the BSD variant does not.
+.TP
+.BR pselect ()
+Linux 2.6.16.
+POSIX.1g, POSIX.1-2001.
+.IP
+Prior to this,
+it was emulated in glibc (but see BUGS).
+.TP
+.B fd_set
+POSIX.1-2001.
+.SH NOTES
+The following header also provides the
+.I fd_set
+type:
+.IR <sys/time.h> .
+.P
+An
+.I fd_set
+is a fixed size buffer.
+Executing
+.BR FD_CLR ()
+or
+.BR FD_SET ()
+with a value of
+.I fd
+that is negative or is equal to or larger than
+.B FD_SETSIZE
+will result
+in undefined behavior.
+Moreover, POSIX requires
+.I fd
+to be a valid file descriptor.
+.P
+The operation of
+.BR select ()
+and
+.BR pselect ()
+is not affected by the
+.B O_NONBLOCK
+flag.
+.\"
+.SS The self-pipe trick
+On systems that lack
+.BR pselect (),
+reliable (and more portable) signal trapping can be achieved
+using the self-pipe trick.
+In this technique,
+a signal handler writes a byte to a pipe whose other end
+is monitored by
+.BR select ()
+in the main program.
+(To avoid possibly blocking when writing to a pipe that may be full
+or reading from a pipe that may be empty,
+nonblocking I/O is used when reading from and writing to the pipe.)
+.\"
+.SS Emulating usleep(3)
+Before the advent of
+.BR usleep (3),
+some code employed a call to
+.BR select ()
+with all three sets empty,
+.I nfds
+zero, and a non-NULL
+.I timeout
+as a fairly portable way to sleep with subsecond precision.
+.\"
+.SS Correspondence between select() and poll() notifications
+Within the Linux kernel source,
+.\" fs/select.c
+we find the following definitions which show the correspondence
+between the readable, writable, and exceptional condition notifications of
+.BR select ()
+and the event notifications provided by
+.BR poll (2)
+and
+.BR epoll (7):
+.P
+.in +4n
+.EX
+#define POLLIN_SET  (EPOLLRDNORM | EPOLLRDBAND | EPOLLIN |
+                     EPOLLHUP | EPOLLERR)
+                   /* Ready for reading */
+#define POLLOUT_SET (EPOLLWRBAND | EPOLLWRNORM | EPOLLOUT |
+                     EPOLLERR)
+                   /* Ready for writing */
+#define POLLEX_SET  (EPOLLPRI)
+                   /* Exceptional condition */
+.EE
+.in
+.\"
+.SS Multithreaded applications
+If a file descriptor being monitored by
+.BR select ()
+is closed in another thread, the result is unspecified.
+On some UNIX systems,
+.BR select ()
+unblocks and returns, with an indication that the file descriptor is ready
+(a subsequent I/O operation will likely fail with an error,
+unless another process reopens the file descriptor between the time
+.BR select ()
+returned and the I/O operation is performed).
+On Linux (and some other systems),
+closing the file descriptor in another thread has no effect on
+.BR select ().
+In summary, any application that relies on a particular behavior
+in this scenario must be considered buggy.
+.\"
+.SS C library/kernel differences
+The Linux kernel allows file descriptor sets of arbitrary size,
+determining the length of the sets to be checked from the value of
+.IR nfds .
+However, in the glibc implementation, the
+.I fd_set
+type is fixed in size.
+See also BUGS.
+.P
+The
+.BR pselect ()
+interface described in this page is implemented by glibc.
+The underlying Linux system call is named
+.BR pselect6 ().
+This system call has somewhat different behavior from the glibc
+wrapper function.
+.P
+The Linux
+.BR pselect6 ()
+system call modifies its
+.I timeout
+argument.
+However, the glibc wrapper function hides this behavior
+by using a local variable for the timeout argument that
+is passed to the system call.
+Thus, the glibc
+.BR pselect ()
+function does not modify its
+.I timeout
+argument;
+this is the behavior required by POSIX.1-2001.
+.P
+The final argument of the
+.BR pselect6 ()
+system call is not a
+.I "sigset_t\ *"
+pointer, but is instead a structure of the form:
+.P
+.in +4n
+.EX
+struct {
+    const kernel_sigset_t *ss;   /* Pointer to signal set */
+    size_t ss_len;               /* Size (in bytes) of object
+                                    pointed to by \[aq]ss\[aq] */
+};
+.EE
+.in
+.P
+This allows the system call to obtain both
+a pointer to the signal set and its size,
+while allowing for the fact that most architectures
+support a maximum of 6 arguments to a system call.
+See
+.BR sigprocmask (2)
+for a discussion of the difference between the kernel and libc
+notion of the signal set.
+.\"
+.SS Historical glibc details
+glibc 2.0 provided an incorrect version of
+.BR pselect ()
+that did not take a
+.I sigmask
+argument.
+.P
+From glibc 2.1 to glibc 2.2.1,
+one must define
+.B _GNU_SOURCE
+in order to obtain the declaration of
+.BR pselect ()
+from
+.IR <sys/select.h> .
+.SH BUGS
+POSIX allows an implementation to define an upper limit,
+advertised via the constant
+.BR FD_SETSIZE ,
+on the range of file descriptors that can be specified
+in a file descriptor set.
+The Linux kernel imposes no fixed limit, but the glibc implementation makes
+.I fd_set
+a fixed-size type, with
+.B FD_SETSIZE
+defined as 1024, and the
+.BR FD_* ()
+macros operating according to that limit.
+To monitor file descriptors greater than 1023, use
+.BR poll (2)
+or
+.BR epoll (7)
+instead.
+.P
+The implementation of the
+.I fd_set
+arguments as value-result arguments is a design error that is avoided in
+.BR poll (2)
+and
+.BR epoll (7).
+.P
+According to POSIX,
+.BR select ()
+should check all specified file descriptors in the three file descriptor sets,
+up to the limit
+.IR nfds\-1 .
+However, the current implementation ignores any file descriptor in
+these sets that is greater than the maximum file descriptor number
+that the process currently has open.
+According to POSIX, any such file descriptor that is specified in one
+of the sets should result in the error
+.BR EBADF .
+.P
+Starting with glibc 2.1, glibc provided an emulation of
+.BR pselect ()
+that was implemented using
+.BR sigprocmask (2)
+and
+.BR select ().
+This implementation remained vulnerable to the very race condition that
+.BR pselect ()
+was designed to prevent.
+Modern versions of glibc use the (race-free)
+.BR pselect ()
+system call on kernels where it is provided.
+.P
+On Linux,
+.BR select ()
+may report a socket file descriptor as "ready for reading", while
+nevertheless a subsequent read blocks.
+This could for example
+happen when data has arrived but upon examination has the wrong
+checksum and is discarded.
+There may be other circumstances
+in which a file descriptor is spuriously reported as ready.
+.\" Stevens discusses a case where accept can block after select
+.\" returns successfully because of an intervening RST from the client.
+Thus it may be safer to use
+.B O_NONBLOCK
+on sockets that should not block.
+.\" Maybe the kernel should have returned EIO in such a situation?
+.P
+On Linux,
+.BR select ()
+also modifies
+.I timeout
+if the call is interrupted by a signal handler (i.e., the
+.B EINTR
+error return).
+This is not permitted by POSIX.1.
+The Linux
+.BR pselect ()
+system call has the same behavior,
+but the glibc wrapper hides this behavior by internally copying the
+.I timeout
+to a local variable and passing that variable to the system call.
+.SH EXAMPLES
+.\" SRC BEGIN (select.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/select.h>
+\&
+int
+main(void)
+{
+    int             retval;
+    fd_set          rfds;
+    struct timeval  tv;
+\&
+    /* Watch stdin (fd 0) to see when it has input. */
+\&
+    FD_ZERO(&rfds);
+    FD_SET(0, &rfds);
+\&
+    /* Wait up to five seconds. */
+\&
+    tv.tv_sec = 5;
+    tv.tv_usec = 0;
+\&
+    retval = select(1, &rfds, NULL, NULL, &tv);
+    /* Don\[aq]t rely on the value of tv now! */
+\&
+    if (retval == \-1)
+        perror("select()");
+    else if (retval)
+        printf("Data is available now.\en");
+        /* FD_ISSET(0, &rfds) will be true. */
+    else
+        printf("No data within five seconds.\en");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR accept (2),
+.BR connect (2),
+.BR poll (2),
+.BR read (2),
+.BR recv (2),
+.BR restart_syscall (2),
+.BR send (2),
+.BR sigprocmask (2),
+.BR write (2),
+.BR timespec (3),
+.BR epoll (7),
+.BR time (7)
+.P
+For a tutorial with discussion and examples, see
+.BR select_tut (2).
diff --git a/man/man2/select_tut.2 b/man/man2/select_tut.2
new file mode 100644
index 000000000..59c241973
--- /dev/null
+++ b/man/man2/select_tut.2
@@ -0,0 +1,638 @@
+.\" This manpage is copyright (C) 2001 Paul Sheer.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" very minor changes, aeb
+.\"
+.\" Modified 5 June 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2006-05-13, mtk, removed much material that is redundant with select.2
+.\"             various other changes
+.\" 2008-01-26, mtk, substantial changes and rewrites
+.\"
+.TH SELECT_TUT 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+select, pselect \- synchronous I/O multiplexing
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+See
+.BR select (2)
+.SH DESCRIPTION
+The
+.BR select ()
+and
+.BR pselect ()
+system calls are used to efficiently monitor multiple file descriptors,
+to see if any of them is, or becomes, "ready";
+that is, to see whether I/O becomes possible,
+or an "exceptional condition" has occurred on any of the file descriptors.
+.P
+This page provides background and tutorial information
+on the use of these system calls.
+For details of the arguments and semantics of
+.BR select ()
+and
+.BR pselect (),
+see
+.BR select (2).
+.\"
+.SS Combining signal and data events
+.BR pselect ()
+is useful if you are waiting for a signal as well as
+for file descriptor(s) to become ready for I/O.
+Programs that receive signals
+normally use the signal handler only to raise a global flag.
+The global flag will indicate that the event must be processed
+in the main loop of the program.
+A signal will cause the
+.BR select ()
+(or
+.BR pselect ())
+call to return with \fIerrno\fP set to \fBEINTR\fP.
+This behavior is essential so that signals can be processed
+in the main loop of the program, otherwise
+.BR select ()
+would block indefinitely.
+.P
+Now, somewhere
+in the main loop will be a conditional to check the global flag.
+So we must ask:
+what if a signal arrives after the conditional, but before the
+.BR select ()
+call?
+The answer is that
+.BR select ()
+would block indefinitely, even though an event is actually pending.
+This race condition is solved by the
+.BR pselect ()
+call.
+This call can be used to set the signal mask to a set of signals
+that are to be received only within the
+.BR pselect ()
+call.
+For instance, let us say that the event in question
+was the exit of a child process.
+Before the start of the main loop, we
+would block \fBSIGCHLD\fP using
+.BR sigprocmask (2).
+Our
+.BR pselect ()
+call would enable
+.B SIGCHLD
+by using an empty signal mask.
+Our program would look like:
+.P
+.EX
+static volatile sig_atomic_t got_SIGCHLD = 0;
+\&
+static void
+child_sig_handler(int sig)
+{
+    got_SIGCHLD = 1;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    sigset_t sigmask, empty_mask;
+    struct sigaction sa;
+    fd_set readfds, writefds, exceptfds;
+    int r;
+\&
+    sigemptyset(&sigmask);
+    sigaddset(&sigmask, SIGCHLD);
+    if (sigprocmask(SIG_BLOCK, &sigmask, NULL) == \-1) {
+        perror("sigprocmask");
+        exit(EXIT_FAILURE);
+    }
+\&
+    sa.sa_flags = 0;
+    sa.sa_handler = child_sig_handler;
+    sigemptyset(&sa.sa_mask);
+    if (sigaction(SIGCHLD, &sa, NULL) == \-1) {
+        perror("sigaction");
+        exit(EXIT_FAILURE);
+    }
+\&
+    sigemptyset(&empty_mask);
+\&
+    for (;;) {          /* main loop */
+        /* Initialize readfds, writefds, and exceptfds
+           before the pselect() call. (Code omitted.) */
+\&
+        r = pselect(nfds, &readfds, &writefds, &exceptfds,
+                    NULL, &empty_mask);
+        if (r == \-1 && errno != EINTR) {
+            /* Handle error */
+        }
+\&
+        if (got_SIGCHLD) {
+            got_SIGCHLD = 0;
+\&
+            /* Handle signalled event here; e.g., wait() for all
+               terminated children. (Code omitted.) */
+        }
+\&
+        /* main body of program */
+    }
+}
+.EE
+.SS Practical
+So what is the point of
+.BR select ()?
+Can't I just read and write to my file descriptors whenever I want?
+The point of
+.BR select ()
+is that it watches
+multiple descriptors at the same time and properly puts the process to
+sleep if there is no activity.
+UNIX programmers often find
+themselves in a position where they have to handle I/O from more than one
+file descriptor where the data flow may be intermittent.
+If you were to merely create a sequence of
+.BR read (2)
+and
+.BR write (2)
+calls, you would
+find that one of your calls may block waiting for data from/to a file
+descriptor, while another file descriptor is unused though ready for I/O.
+.BR select ()
+efficiently copes with this situation.
+.SS Select law
+Many people who try to use
+.BR select ()
+come across behavior that is
+difficult to understand and produces nonportable or borderline results.
+For instance, the above program is carefully written not to
+block at any point, even though it does not set its file descriptors to
+nonblocking mode.
+It is easy to introduce
+subtle errors that will remove the advantage of using
+.BR select (),
+so here is a list of essentials to watch for when using
+.BR select ().
+.TP 4
+1.
+You should always try to use
+.BR select ()
+without a timeout.
+Your program
+should have nothing to do if there is no data available.
+Code that
+depends on timeouts is not usually portable and is difficult to debug.
+.TP
+2.
+The value \fInfds\fP must be properly calculated for efficiency as
+explained above.
+.TP
+3.
+No file descriptor must be added to any set if you do not intend
+to check its result after the
+.BR select ()
+call, and respond appropriately.
+See next rule.
+.TP
+4.
+After
+.BR select ()
+returns, all file descriptors in all sets
+should be checked to see if they are ready.
+.TP
+5.
+The functions
+.BR read (2),
+.BR recv (2),
+.BR write (2),
+and
+.BR send (2)
+do \fInot\fP necessarily read/write the full amount of data
+that you have requested.
+If they do read/write the full amount, it's
+because you have a low traffic load and a fast stream.
+This is not always going to be the case.
+You should cope with the case of your
+functions managing to send or receive only a single byte.
+.TP
+6.
+Never read/write only in single bytes at a time unless you are really
+sure that you have a small amount of data to process.
+It is extremely
+inefficient not to read/write as much data as you can buffer each time.
+The buffers in the example below are 1024 bytes although they could
+easily be made larger.
+.TP
+7.
+Calls to
+.BR read (2),
+.BR recv (2),
+.BR write (2),
+.BR send (2),
+and
+.BR select ()
+can fail with the error
+\fBEINTR\fP,
+and calls to
+.BR read (2),
+.BR recv (2),
+.BR write (2),
+and
+.BR send (2)
+can fail with
+.I errno
+set to \fBEAGAIN\fP (\fBEWOULDBLOCK\fP).
+These results must be properly managed (not done properly above).
+If your program is not going to receive any signals, then
+it is unlikely you will get \fBEINTR\fP.
+If your program does not set nonblocking I/O,
+you will not get \fBEAGAIN\fP.
+.\" Nonetheless, you should still cope with these errors for completeness.
+.TP
+8.
+Never call
+.BR read (2),
+.BR recv (2),
+.BR write (2),
+or
+.BR send (2)
+with a buffer length of zero.
+.TP
+9.
+If the functions
+.BR read (2),
+.BR recv (2),
+.BR write (2),
+and
+.BR send (2)
+fail with errors other than those listed in \fB7.\fP,
+or one of the input functions returns 0, indicating end of file,
+then you should \fInot\fP pass that file descriptor to
+.BR select ()
+again.
+In the example below,
+I close the file descriptor immediately, and then set it to \-1
+to prevent it being included in a set.
+.TP
+10.
+The timeout value must be initialized with each new call to
+.BR select (),
+since some operating systems modify the structure.
+.BR pselect ()
+however does not modify its timeout structure.
+.TP
+11.
+Since
+.BR select ()
+modifies its file descriptor sets,
+if the call is being used in a loop,
+then the sets must be reinitialized before each call.
+.\" "I have heard" does not fill me with confidence, and doesn't
+.\" belong in a man page, so I've commented this point out.
+.\" .TP
+.\" 11.
+.\" I have heard that the Windows socket layer does not cope with OOB data
+.\" properly.
+.\" It also does not cope with
+.\" .BR select ()
+.\" calls when no file descriptors are set at all.
+.\" Having no file descriptors set is a useful
+.\" way to sleep the process with subsecond precision by using the timeout.
+.\" (See further on.)
+.SH RETURN VALUE
+See
+.BR select (2).
+.SH NOTES
+Generally speaking,
+all operating systems that support sockets also support
+.BR select ().
+.BR select ()
+can be used to solve
+many problems in a portable and efficient way that naive programmers try
+to solve in a more complicated manner using
+threads, forking, IPCs, signals, memory sharing, and so on.
+.P
+The
+.BR poll (2)
+system call has the same functionality as
+.BR select (),
+and is somewhat more efficient when monitoring sparse
+file descriptor sets.
+It is nowadays widely available, but historically was less portable than
+.BR select ().
+.P
+The Linux-specific
+.BR epoll (7)
+API provides an interface that is more efficient than
+.BR select (2)
+and
+.BR poll (2)
+when monitoring large numbers of file descriptors.
+.SH EXAMPLES
+Here is an example that better demonstrates the true utility of
+.BR select ().
+The listing below is a TCP forwarding program that forwards
+from one TCP port to another.
+.P
+.\" SRC BEGIN (select.c)
+.EX
+#include <arpa/inet.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <unistd.h>
+\&
+static int forward_port;
+\&
+#undef max
+#define max(x, y) ((x) > (y) ? (x) : (y))
+\&
+static int
+listen_socket(int listen_port)
+{
+    int                 lfd;
+    int                 yes;
+    struct sockaddr_in  addr;
+\&
+    lfd = socket(AF_INET, SOCK_STREAM, 0);
+    if (lfd == \-1) {
+        perror("socket");
+        return \-1;
+    }
+\&
+    yes = 1;
+    if (setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR,
+                   &yes, sizeof(yes)) == \-1)
+    {
+        perror("setsockopt");
+        close(lfd);
+        return \-1;
+    }
+\&
+    memset(&addr, 0, sizeof(addr));
+    addr.sin_port = htons(listen_port);
+    addr.sin_family = AF_INET;
+    if (bind(lfd, (struct sockaddr *) &addr, sizeof(addr)) == \-1) {
+        perror("bind");
+        close(lfd);
+        return \-1;
+    }
+\&
+    printf("accepting connections on port %d\en", listen_port);
+    listen(lfd, 10);
+    return lfd;
+}
+\&
+static int
+connect_socket(int connect_port, char *address)
+{
+    int                 cfd;
+    struct sockaddr_in  addr;
+\&
+    cfd = socket(AF_INET, SOCK_STREAM, 0);
+    if (cfd == \-1) {
+        perror("socket");
+        return \-1;
+    }
+\&
+    memset(&addr, 0, sizeof(addr));
+    addr.sin_port = htons(connect_port);
+    addr.sin_family = AF_INET;
+\&
+    if (!inet_aton(address, (struct in_addr *) &addr.sin_addr.s_addr)) {
+        fprintf(stderr, "inet_aton(): bad IP address format\en");
+        close(cfd);
+        return \-1;
+    }
+\&
+    if (connect(cfd, (struct sockaddr *) &addr, sizeof(addr)) == \-1) {
+        perror("connect()");
+        shutdown(cfd, SHUT_RDWR);
+        close(cfd);
+        return \-1;
+    }
+    return cfd;
+}
+\&
+#define SHUT_FD1 do {                                \e
+                     if (fd1 >= 0) {                 \e
+                         shutdown(fd1, SHUT_RDWR);   \e
+                         close(fd1);                 \e
+                         fd1 = \-1;                   \e
+                     }                               \e
+                 } while (0)
+\&
+#define SHUT_FD2 do {                                \e
+                     if (fd2 >= 0) {                 \e
+                         shutdown(fd2, SHUT_RDWR);   \e
+                         close(fd2);                 \e
+                         fd2 = \-1;                   \e
+                     }                               \e
+                 } while (0)
+\&
+#define BUF_SIZE 1024
+\&
+int
+main(int argc, char *argv[])
+{
+    int      h;
+    int      ready, nfds;
+    int      fd1 = \-1, fd2 = \-1;
+    int      buf1_avail = 0, buf1_written = 0;
+    int      buf2_avail = 0, buf2_written = 0;
+    char     buf1[BUF_SIZE], buf2[BUF_SIZE];
+    fd_set   readfds, writefds, exceptfds;
+    ssize_t  nbytes;
+\&
+    if (argc != 4) {
+        fprintf(stderr, "Usage\en\etfwd <listen\-port> "
+                "<forward\-to\-port> <forward\-to\-ip\-address>\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    signal(SIGPIPE, SIG_IGN);
+\&
+    forward_port = atoi(argv[2]);
+\&
+    h = listen_socket(atoi(argv[1]));
+    if (h == \-1)
+        exit(EXIT_FAILURE);
+\&
+    for (;;) {
+        nfds = 0;
+\&
+        FD_ZERO(&readfds);
+        FD_ZERO(&writefds);
+        FD_ZERO(&exceptfds);
+        FD_SET(h, &readfds);
+        nfds = max(nfds, h);
+\&
+        if (fd1 > 0 && buf1_avail < BUF_SIZE)
+            FD_SET(fd1, &readfds);
+            /* Note: nfds is updated below, when fd1 is added to
+               exceptfds. */
+        if (fd2 > 0 && buf2_avail < BUF_SIZE)
+            FD_SET(fd2, &readfds);
+\&
+        if (fd1 > 0 && buf2_avail \- buf2_written > 0)
+            FD_SET(fd1, &writefds);
+        if (fd2 > 0 && buf1_avail \- buf1_written > 0)
+            FD_SET(fd2, &writefds);
+\&
+        if (fd1 > 0) {
+            FD_SET(fd1, &exceptfds);
+            nfds = max(nfds, fd1);
+        }
+        if (fd2 > 0) {
+            FD_SET(fd2, &exceptfds);
+            nfds = max(nfds, fd2);
+        }
+\&
+        ready = select(nfds + 1, &readfds, &writefds, &exceptfds, NULL);
+\&
+        if (ready == \-1 && errno == EINTR)
+            continue;
+\&
+        if (ready == \-1) {
+            perror("select()");
+            exit(EXIT_FAILURE);
+        }
+\&
+        if (FD_ISSET(h, &readfds)) {
+            socklen_t addrlen;
+            struct sockaddr_in client_addr;
+            int fd;
+\&
+            addrlen = sizeof(client_addr);
+            memset(&client_addr, 0, addrlen);
+            fd = accept(h, (struct sockaddr *) &client_addr, &addrlen);
+            if (fd == \-1) {
+                perror("accept()");
+            } else {
+                SHUT_FD1;
+                SHUT_FD2;
+                buf1_avail = buf1_written = 0;
+                buf2_avail = buf2_written = 0;
+                fd1 = fd;
+                fd2 = connect_socket(forward_port, argv[3]);
+                if (fd2 == \-1)
+                    SHUT_FD1;
+                else
+                    printf("connect from %s\en",
+                           inet_ntoa(client_addr.sin_addr));
+\&
+                /* Skip any events on the old, closed file
+                   descriptors. */
+\&
+                continue;
+            }
+        }
+\&
+        /* NB: read OOB data before normal reads. */
+\&
+        if (fd1 > 0 && FD_ISSET(fd1, &exceptfds)) {
+            char c;
+\&
+            nbytes = recv(fd1, &c, 1, MSG_OOB);
+            if (nbytes < 1)
+                SHUT_FD1;
+            else
+                send(fd2, &c, 1, MSG_OOB);
+        }
+        if (fd2 > 0 && FD_ISSET(fd2, &exceptfds)) {
+            char c;
+\&
+            nbytes = recv(fd2, &c, 1, MSG_OOB);
+            if (nbytes < 1)
+                SHUT_FD2;
+            else
+                send(fd1, &c, 1, MSG_OOB);
+        }
+        if (fd1 > 0 && FD_ISSET(fd1, &readfds)) {
+            nbytes = read(fd1, buf1 + buf1_avail,
+                          BUF_SIZE \- buf1_avail);
+            if (nbytes < 1)
+                SHUT_FD1;
+            else
+                buf1_avail += nbytes;
+        }
+        if (fd2 > 0 && FD_ISSET(fd2, &readfds)) {
+            nbytes = read(fd2, buf2 + buf2_avail,
+                          BUF_SIZE \- buf2_avail);
+            if (nbytes < 1)
+                SHUT_FD2;
+            else
+                buf2_avail += nbytes;
+        }
+        if (fd1 > 0 && FD_ISSET(fd1, &writefds) && buf2_avail > 0) {
+            nbytes = write(fd1, buf2 + buf2_written,
+                           buf2_avail \- buf2_written);
+            if (nbytes < 1)
+                SHUT_FD1;
+            else
+                buf2_written += nbytes;
+        }
+        if (fd2 > 0 && FD_ISSET(fd2, &writefds) && buf1_avail > 0) {
+            nbytes = write(fd2, buf1 + buf1_written,
+                           buf1_avail \- buf1_written);
+            if (nbytes < 1)
+                SHUT_FD2;
+            else
+                buf1_written += nbytes;
+        }
+\&
+        /* Check if write data has caught read data. */
+\&
+        if (buf1_written == buf1_avail)
+            buf1_written = buf1_avail = 0;
+        if (buf2_written == buf2_avail)
+            buf2_written = buf2_avail = 0;
+\&
+        /* One side has closed the connection, keep
+           writing to the other side until empty. */
+\&
+        if (fd1 < 0 && buf1_avail \- buf1_written == 0)
+            SHUT_FD2;
+        if (fd2 < 0 && buf2_avail \- buf2_written == 0)
+            SHUT_FD1;
+    }
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.P
+The above program properly forwards most kinds of TCP connections
+including OOB signal data transmitted by \fBtelnet\fP servers.
+It handles the tricky problem of having data flow in both directions
+simultaneously.
+You might think it more efficient to use a
+.BR fork (2)
+call and devote a thread to each stream.
+This becomes more tricky than you might suspect.
+Another idea is to set nonblocking I/O using
+.BR fcntl (2).
+This also has its problems because you end up using
+inefficient timeouts.
+.P
+The program does not handle more than one simultaneous connection at a
+time, although it could easily be extended to do this with a linked list
+of buffers\[em]one for each connection.
+At the moment, new
+connections cause the current connection to be dropped.
+.SH SEE ALSO
+.BR accept (2),
+.BR connect (2),
+.BR poll (2),
+.BR read (2),
+.BR recv (2),
+.BR select (2),
+.BR send (2),
+.BR sigprocmask (2),
+.BR write (2),
+.BR epoll (7)
+.\" .SH AUTHORS
+.\" This man page was written by Paul Sheer.
diff --git a/man/man2/semctl.2 b/man/man2/semctl.2
new file mode 100644
index 000000000..243919c73
--- /dev/null
+++ b/man/man2/semctl.2
@@ -0,0 +1,623 @@
+'\" t
+.\" Copyright 1993 Giorgio Ciucci (giorgio@crcc.it)
+.\" and Copyright 2004, 2005 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Tue Oct 22 17:53:56 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Fri Jun 19 10:59:15 1998 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Sun Feb 18 01:59:29 2001 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 20 Dec 2001, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 21 Dec 2001, aeb
+.\" Modified 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on CAP_IPC_OWNER requirement
+.\" Modified 17 Jun 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on CAP_SYS_ADMIN requirement for IPC_SET and IPC_RMID
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Rewrote semun text
+.\"	Added semid_ds and ipc_perm structure definitions
+.\" 2005-08-02, mtk: Added IPC_INFO, SEM_INFO, SEM_STAT descriptions.
+.\" 2018-03-20, dbueso: Added SEM_STAT_ANY description.
+.\"
+.TH semctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+semctl \- System V semaphore control operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/sem.h>
+.P
+.BI "int semctl(int " semid ", int " semnum ", int " op ", ...);"
+.fi
+.SH DESCRIPTION
+.BR semctl ()
+performs the control operation specified by
+.I op
+on the System\ V semaphore set identified by
+.IR semid ,
+or on the
+.IR semnum -th
+semaphore of that set.
+(The semaphores in a set are numbered starting at 0.)
+.P
+This function has three or four arguments, depending on
+.IR op .
+When there are four, the fourth has the type
+.IR "union semun" .
+The \fIcalling program\fP must define this union as follows:
+.P
+.in +4n
+.EX
+union semun {
+    int              val;    /* Value for SETVAL */
+    struct semid_ds *buf;    /* Buffer for IPC_STAT, IPC_SET */
+    unsigned short  *array;  /* Array for GETALL, SETALL */
+    struct seminfo  *__buf;  /* Buffer for IPC_INFO
+                                (Linux\-specific) */
+};
+.EE
+.in
+.P
+The
+.I semid_ds
+data structure is defined in \fI<sys/sem.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct semid_ds {
+    struct ipc_perm sem_perm;  /* Ownership and permissions */
+    time_t          sem_otime; /* Last semop time */
+    time_t          sem_ctime; /* Creation time/time of last
+                                  modification via semctl() */
+    unsigned long   sem_nsems; /* No. of semaphores in set */
+};
+.EE
+.in
+.P
+The fields of the
+.I semid_ds
+structure are as follows:
+.TP 11
+.I sem_perm
+This is an
+.I ipc_perm
+structure (see below) that specifies the access permissions on the semaphore
+set.
+.TP
+.I sem_otime
+Time of last
+.BR semop (2)
+system call.
+.TP
+.I sem_ctime
+Time of creation of semaphore set or time of last
+.BR semctl ()
+.BR IPCSET ,
+.BR SETVAL ,
+or
+.B SETALL
+operation.
+.TP
+.I sem_nsems
+Number of semaphores in the set.
+Each semaphore of the set is referenced by a nonnegative integer
+ranging from
+.B 0
+to
+.IR sem_nsems\-1 .
+.P
+The
+.I ipc_perm
+structure is defined as follows
+(the highlighted fields are settable using
+.BR IPC_SET ):
+.P
+.in +4n
+.EX
+struct ipc_perm {
+    key_t          __key; /* Key supplied to semget(2) */
+    uid_t          \fBuid\fP;   /* Effective UID of owner */
+    gid_t          \fBgid\fP;   /* Effective GID of owner */
+    uid_t          cuid;  /* Effective UID of creator */
+    gid_t          cgid;  /* Effective GID of creator */
+    unsigned short \fBmode\fP;  /* Permissions */
+    unsigned short __seq; /* Sequence number */
+};
+.EE
+.in
+.P
+The least significant 9 bits of the
+.I mode
+field of the
+.I ipc_perm
+structure define the access permissions for the shared memory segment.
+The permission bits are as follows:
+.TS
+l l.
+0400	Read by user
+0200	Write by user
+0040	Read by group
+0020	Write by group
+0004	Read by others
+0002	Write by others
+.TE
+.P
+In effect, "write" means "alter" for a semaphore set.
+Bits 0100, 0010, and 0001 (the execute bits) are unused by the system.
+.P
+Valid values for
+.I op
+are:
+.TP
+.B IPC_STAT
+Copy information from the kernel data structure associated with
+.I semid
+into the
+.I semid_ds
+structure pointed to by
+.IR arg.buf .
+The argument
+.I semnum
+is ignored.
+The calling process must have read permission on the semaphore set.
+.TP
+.B IPC_SET
+Write the values of some members of the
+.I semid_ds
+structure pointed to by
+.I arg.buf
+to the kernel data structure associated with this semaphore set,
+updating also its
+.I sem_ctime
+member.
+.IP
+The following members of the structure are updated:
+.IR sem_perm.uid ,
+.IR sem_perm.gid ,
+and (the least significant 9 bits of)
+.IR sem_perm.mode .
+.IP
+The effective UID of the calling process must match the owner
+.RI ( sem_perm.uid )
+or creator
+.RI ( sem_perm.cuid )
+of the semaphore set, or the caller must be privileged.
+The argument
+.I semnum
+is ignored.
+.TP
+.B IPC_RMID
+Immediately remove the semaphore set,
+awakening all processes blocked in
+.BR semop (2)
+calls on the set (with an error return and
+.I errno
+set to
+.BR EIDRM ).
+The effective user ID of the calling process must
+match the creator or owner of the semaphore set,
+or the caller must be privileged.
+The argument
+.I semnum
+is ignored.
+.TP
+.BR IPC_INFO " (Linux\-specific)"
+Return information about system-wide semaphore limits and
+parameters in the structure pointed to by
+.IR arg.__buf .
+This structure is of type
+.IR seminfo ,
+defined in
+.I <sys/sem.h>
+if the
+.B _GNU_SOURCE
+feature test macro is defined:
+.IP
+.in +4n
+.EX
+struct  seminfo {
+    int semmap;  /* Number of entries in semaphore
+                    map; unused within kernel */
+    int semmni;  /* Maximum number of semaphore sets */
+    int semmns;  /* Maximum number of semaphores in all
+                    semaphore sets */
+    int semmnu;  /* System\-wide maximum number of undo
+                    structures; unused within kernel */
+    int semmsl;  /* Maximum number of semaphores in a
+                    set */
+    int semopm;  /* Maximum number of operations for
+                    semop(2) */
+    int semume;  /* Maximum number of undo entries per
+                    process; unused within kernel */
+    int semusz;  /* Size of struct sem_undo */
+    int semvmx;  /* Maximum semaphore value */
+    int semaem;  /* Max. value that can be recorded for
+                    semaphore adjustment (SEM_UNDO) */
+};
+.EE
+.in
+.IP
+The
+.IR semmsl ,
+.IR semmns ,
+.IR semopm ,
+and
+.I semmni
+settings can be changed via
+.IR /proc/sys/kernel/sem ;
+see
+.BR proc (5)
+for details.
+.TP
+.BR SEM_INFO " (Linux-specific)"
+Return a
+.I seminfo
+structure containing the same information as for
+.BR IPC_INFO ,
+except that the following fields are returned with information
+about system resources consumed by semaphores: the
+.I semusz
+field returns the number of semaphore sets that currently exist
+on the system; and the
+.I semaem
+field returns the total number of semaphores in all semaphore sets
+on the system.
+.TP
+.BR SEM_STAT " (Linux-specific)"
+Return a
+.I semid_ds
+structure as for
+.BR IPC_STAT .
+However, the
+.I semid
+argument is not a semaphore identifier, but instead an index into
+the kernel's internal array that maintains information about
+all semaphore sets on the system.
+.TP
+.BR SEM_STAT_ANY " (Linux-specific, since Linux 4.17)"
+Return a
+.I semid_ds
+structure as for
+.BR SEM_STAT .
+However,
+.I sem_perm.mode
+is not checked for read access for
+.I semid
+meaning that any user can employ this operation (just as any user may read
+.I /proc/sysvipc/sem
+to obtain the same information).
+.TP
+.B GETALL
+Return
+.B semval
+(i.e., the current value)
+for all semaphores of the set into
+.IR arg.array .
+The argument
+.I semnum
+is ignored.
+The calling process must have read permission on the semaphore set.
+.TP
+.B GETNCNT
+Return the
+.B semncnt
+value for the
+.IR semnum \-th
+semaphore of the set
+(i.e., the number of processes waiting for the semaphore's value to increase).
+The calling process must have read permission on the semaphore set.
+.TP
+.B GETPID
+Return the
+.B sempid
+value for the
+.IR semnum \-th
+semaphore of the set.
+This is the PID of the process that last performed an operation on
+that semaphore (but see NOTES).
+The calling process must have read permission on the semaphore set.
+.TP
+.B GETVAL
+Return
+.B semval
+(i.e., the semaphore value) for the
+.IR semnum \-th
+semaphore of the set.
+The calling process must have read permission on the semaphore set.
+.TP
+.B GETZCNT
+Return the
+.B semzcnt
+value for the
+.IR semnum \-th
+semaphore of the set
+(i.e., the number of processes waiting for the semaphore value to become 0).
+The calling process must have read permission on the semaphore set.
+.TP
+.B SETALL
+Set the
+.B semval
+values for all semaphores of the set using
+.IR arg.array ,
+updating also the
+.I sem_ctime
+member of the
+.I semid_ds
+structure associated with the set.
+Undo entries (see
+.BR semop (2))
+are cleared for altered semaphores in all processes.
+If the changes to semaphore values would permit blocked
+.BR semop (2)
+calls in other processes to proceed, then those processes are woken up.
+The argument
+.I semnum
+is ignored.
+The calling process must have alter (write) permission on
+the semaphore set.
+.TP
+.B SETVAL
+Set the semaphore value
+.RB ( semval )
+to
+.I arg.val
+for the
+.IR semnum \-th
+semaphore of the set, updating also the
+.I sem_ctime
+member of the
+.I semid_ds
+structure associated with the set.
+Undo entries are cleared for altered semaphores in all processes.
+If the changes to semaphore values would permit blocked
+.BR semop (2)
+calls in other processes to proceed, then those processes are woken up.
+The calling process must have alter permission on the semaphore set.
+.SH RETURN VALUE
+On success,
+.BR semctl ()
+returns a nonnegative value depending on
+.I op
+as follows:
+.TP
+.B GETNCNT
+the value of
+.BR semncnt .
+.TP
+.B GETPID
+the value of
+.BR sempid .
+.TP
+.B GETVAL
+the value of
+.BR semval .
+.TP
+.B GETZCNT
+the value of
+.BR semzcnt .
+.TP
+.B IPC_INFO
+the index of the highest used entry in the
+kernel's internal array recording information about all
+semaphore sets.
+(This information can be used with repeated
+.B SEM_STAT
+or
+.B SEM_STAT_ANY
+operations to obtain information about all semaphore sets on the system.)
+.TP
+.B SEM_INFO
+as for
+.BR IPC_INFO .
+.TP
+.B SEM_STAT
+the identifier of the semaphore set whose index was given in
+.IR semid .
+.TP
+.B SEM_STAT_ANY
+as for
+.BR SEM_STAT .
+.P
+All other
+.I op
+values return 0 on success.
+.P
+On failure,
+.BR semctl ()
+returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The argument
+.I op
+has one of the values
+.BR GETALL ,
+.BR GETPID ,
+.BR GETVAL ,
+.BR GETNCNT ,
+.BR GETZCNT ,
+.BR IPC_STAT ,
+.BR SEM_STAT ,
+.BR SEM_STAT_ANY ,
+.BR SETALL ,
+or
+.B SETVAL
+and the calling process does not have the required
+permissions on the semaphore set and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EFAULT
+The address pointed to by
+.I arg.buf
+or
+.I arg.array
+isn't accessible.
+.TP
+.B EIDRM
+The semaphore set was removed.
+.TP
+.B EINVAL
+Invalid value for
+.I op
+or
+.IR semid .
+Or: for a
+.B SEM_STAT
+operation, the index value specified in
+.I semid
+referred to an array slot that is currently unused.
+.TP
+.B EPERM
+The argument
+.I op
+has the value
+.B IPC_SET
+or
+.B IPC_RMID
+but the effective user ID of the calling process is not the creator
+(as found in
+.IR sem_perm.cuid )
+or the owner
+(as found in
+.IR sem_perm.uid )
+of the semaphore set,
+and the process does not have the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B ERANGE
+The argument
+.I op
+has the value
+.B SETALL
+or
+.B SETVAL
+and the value to which
+.B semval
+is to be set (for some semaphore of the set) is less than 0
+or greater than the implementation limit
+.BR SEMVMX .
+.SH VERSIONS
+POSIX.1 specifies the
+.\" POSIX.1-2001, POSIX.1-2008
+.I sem_nsems
+field of the
+.I semid_ds
+structure as having the type
+.IR "unsigned\ short" ,
+and the field is so defined on most other systems.
+It was also so defined on Linux 2.2 and earlier,
+but, since Linux 2.4, the field has the type
+.IR "unsigned\ long" .
+.\"
+.SS The sempid value
+POSIX.1 defines
+.I sempid
+as the "process ID of [the] last operation" on a semaphore,
+and explicitly notes that this value is set by a successful
+.BR semop (2)
+call, with the implication that no other interface affects the
+.I sempid
+value.
+.P
+While some implementations conform to the behavior specified in POSIX.1,
+others do not.
+(The fault here probably lies with POSIX.1 inasmuch as it likely failed
+to capture the full range of existing implementation behaviors.)
+Various other implementations
+.\" At least OpenSolaris (and, one supposes, older Solaris) and Darwin
+also update
+.I sempid
+for the other operations that update the value of a semaphore: the
+.B SETVAL
+and
+.B SETALL
+operations, as well as the semaphore adjustments performed
+on process termination as a consequence of the use of the
+.B SEM_UNDO
+flag (see
+.BR semop (2)).
+.P
+Linux also updates
+.I sempid
+for
+.B SETVAL
+operations and semaphore adjustments.
+However, somewhat inconsistently, up to and including Linux 4.5,
+the kernel did not update
+.I sempid
+for
+.B SETALL
+operations.
+This was rectified
+.\" commit a5f4db877177d2a3d7ae62a7bac3a5a27e083d7f
+in Linux 4.6.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.\" SVr4 documents more error conditions EINVAL and EOVERFLOW.
+.P
+Various fields in a \fIstruct semid_ds\fP were typed as
+.I short
+under Linux 2.2
+and have become
+.I long
+under Linux 2.4.
+To take advantage of this,
+a recompilation under glibc-2.1.91 or later should suffice.
+(The kernel distinguishes old and new calls by an
+.B IPC_64
+flag in
+.IR op .)
+.P
+In some earlier versions of glibc, the
+.I semun
+union was defined in \fI<sys/sem.h>\fP, but POSIX.1 requires
+.\" POSIX.1-2001, POSIX.1-2008
+that the caller define this union.
+On versions of glibc where this union is \fInot\fP defined,
+the macro
+.B _SEM_SEMUN_UNDEFINED
+is defined in \fI<sys/sem.h>\fP.
+.SH NOTES
+The
+.BR IPC_INFO ,
+.BR SEM_STAT ,
+and
+.B SEM_INFO
+operations are used by the
+.BR ipcs (1)
+program to provide information on allocated resources.
+In the future these may modified or moved to a
+.I /proc
+filesystem interface.
+.P
+The following system limit on semaphore sets affects a
+.BR semctl ()
+call:
+.TP
+.B SEMVMX
+Maximum value for
+.BR semval :
+implementation dependent (32767).
+.P
+For greater portability, it is best to always call
+.BR semctl ()
+with four arguments.
+.SH EXAMPLES
+See
+.BR shmop (2).
+.SH SEE ALSO
+.BR ipc (2),
+.BR semget (2),
+.BR semop (2),
+.BR capabilities (7),
+.BR sem_overview (7),
+.BR sysvipc (7)
diff --git a/man/man2/semget.2 b/man/man2/semget.2
new file mode 100644
index 000000000..167957b3a
--- /dev/null
+++ b/man/man2/semget.2
@@ -0,0 +1,434 @@
+.\" Copyright 1993 Giorgio Ciucci (giorgio@crcc.it)
+.\" and Copyright (C) 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Tue Oct 22 17:54:56 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1 Jan 2002, Martin Schulze <joey@infodrom.org>
+.\" Modified 4 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Added notes on /proc files
+.\"	Rewrote BUGS note about semget()'s failure to initialize
+.\"		semaphore values
+.\"
+.TH semget 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+semget \- get a System V semaphore set identifier
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/sem.h>
+.fi
+.P
+.BI "int semget(key_t " key ,
+.BI "int " nsems ,
+.BI "int " semflg );
+.SH DESCRIPTION
+The
+.BR semget ()
+system call returns the System\ V semaphore set identifier
+associated with the argument
+.IR key .
+It may be used either to obtain the identifier of a previously created
+semaphore set (when
+.I semflg
+is zero and
+.I key
+does not have the value
+.BR IPC_PRIVATE ),
+or to create a new set.
+.P
+A new set of
+.I nsems
+semaphores is created if
+.I key
+has the value
+.B IPC_PRIVATE
+or if no existing semaphore set is associated with
+.I key
+and
+.B IPC_CREAT
+is specified in
+.IR semflg .
+.P
+If
+.I semflg
+specifies both
+.B IPC_CREAT
+and
+.B IPC_EXCL
+and a semaphore set already exists for
+.IR key ,
+then
+.BR semget ()
+fails with
+.I errno
+set to
+.BR EEXIST .
+(This is analogous to the effect of the combination
+.B O_CREAT | O_EXCL
+for
+.BR open (2).)
+.P
+Upon creation, the least significant 9 bits of the argument
+.I semflg
+define the permissions (for owner, group, and others)
+for the semaphore set.
+These bits have the same format, and the same
+meaning, as the
+.I mode
+argument of
+.BR open (2)
+(though the execute permissions are
+not meaningful for semaphores, and write permissions mean permission
+to alter semaphore values).
+.P
+When creating a new semaphore set,
+.BR semget ()
+initializes the set's associated data structure,
+.I semid_ds
+(see
+.BR semctl (2)),
+as follows:
+.IP \[bu] 3
+.I sem_perm.cuid
+and
+.I sem_perm.uid
+are set to the effective user ID of the calling process.
+.IP \[bu]
+.I sem_perm.cgid
+and
+.I sem_perm.gid
+are set to the effective group ID of the calling process.
+.IP \[bu]
+The least significant 9 bits of
+.I sem_perm.mode
+are set to the least significant 9 bits of
+.IR semflg .
+.IP \[bu]
+.I sem_nsems
+is set to the value of
+.IR nsems .
+.IP \[bu]
+.I sem_otime
+is set to 0.
+.IP \[bu]
+.I sem_ctime
+is set to the current time.
+.P
+The argument
+.I nsems
+can be 0
+(a don't care)
+when a semaphore set is not being created.
+Otherwise,
+.I nsems
+must be greater than 0
+and less than or equal to the maximum number of semaphores per semaphore set
+.RB ( SEMMSL ).
+.P
+If the semaphore set already exists, the permissions are
+verified.
+.\" and a check is made to see if it is marked for destruction.
+.SH RETURN VALUE
+On success,
+.BR semget ()
+returns the semaphore set identifier (a nonnegative integer).
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+A semaphore set exists for
+.IR key ,
+but the calling process does not have permission to access the set,
+and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EEXIST
+.B IPC_CREAT
+and
+.B IPC_EXCL
+were specified in
+.IR semflg ,
+but a semaphore set already exists for
+.IR key .
+.\" .TP
+.\" .B EIDRM
+.\" The semaphore set is marked to be deleted.
+.TP
+.B EINVAL
+.I nsems
+is less than 0 or greater than the limit on the number
+of semaphores per semaphore set
+.RB ( SEMMSL ).
+.TP
+.B EINVAL
+A semaphore set corresponding to
+.I key
+already exists, but
+.I nsems
+is larger than the number of semaphores in that set.
+.TP
+.B ENOENT
+No semaphore set exists for
+.I key
+and
+.I semflg
+did not specify
+.BR IPC_CREAT .
+.TP
+.B ENOMEM
+A semaphore set has to be created but the system does not have
+enough memory for the new data structure.
+.TP
+.B ENOSPC
+A semaphore set has to be created but the system limit for the maximum
+number of semaphore sets
+.RB ( SEMMNI ),
+or the system wide maximum number of semaphores
+.RB ( SEMMNS ),
+would be exceeded.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+SVr4, POSIX.1-2001.
+.\" SVr4 documents additional error conditions EFBIG, E2BIG, EAGAIN,
+.\" ERANGE, EFAULT.
+.SH NOTES
+.B IPC_PRIVATE
+isn't a flag field but a
+.I key_t
+type.
+If this special value is used for
+.IR key ,
+the system call ignores all but the least significant 9 bits of
+.I semflg
+and creates a new semaphore set (on success).
+.\"
+.SS Semaphore initialization
+The values of the semaphores in a newly created set are indeterminate.
+(POSIX.1-2001 and POSIX.1-2008 are explicit on this point,
+although POSIX.1-2008 notes that a future version of the standard
+may require an implementation to initialize the semaphores to 0.)
+Although Linux, like many other implementations,
+initializes the semaphore values to 0,
+a portable application cannot rely on this:
+it should explicitly initialize the semaphores to the desired values.
+.\" In truth, every one of the many implementations that I've tested sets
+.\" the values to zero, but I suppose there is/was some obscure
+.\" implementation out there that does not.
+.P
+Initialization can be done using
+.BR semctl (2)
+.B SETVAL
+or
+.B SETALL
+operation.
+Where multiple peers do not know who will be the first to
+initialize the set, checking for a nonzero
+.I sem_otime
+in the associated data structure retrieved by a
+.BR semctl (2)
+.B IPC_STAT
+operation can be used to avoid races.
+.\"
+.SS Semaphore limits
+The following limits on semaphore set resources affect the
+.BR semget ()
+call:
+.TP
+.B SEMMNI
+System-wide limit on the number of semaphore sets.
+Before Linux 3.19,
+the default value for this limit was 128.
+Since Linux 3.19,
+.\" commit e843e7d2c88b7db107a86bd2c7145dc715c058f4
+the default value is 32,000.
+On Linux, this limit can be read and modified via the fourth field of
+.IR /proc/sys/kernel/sem .
+.\" This /proc file is not available in Linux 2.2 and earlier -- MTK
+.TP
+.B SEMMSL
+Maximum number of semaphores per semaphore ID.
+Before Linux 3.19,
+the default value for this limit was 250.
+Since Linux 3.19,
+.\" commit e843e7d2c88b7db107a86bd2c7145dc715c058f4
+the default value is 32,000.
+On Linux, this limit can be read and modified via the first field of
+.IR /proc/sys/kernel/sem .
+.TP
+.B SEMMNS
+System-wide limit on the number of semaphores: policy dependent
+(on Linux, this limit can be read and modified via the second field of
+.IR /proc/sys/kernel/sem ).
+Note that the number of semaphores system-wide
+is also limited by the product of
+.B SEMMSL
+and
+.BR SEMMNI .
+.SH BUGS
+The name choice
+.B IPC_PRIVATE
+was perhaps unfortunate,
+.B IPC_NEW
+would more clearly show its function.
+.SH EXAMPLES
+The program shown below uses
+.BR semget ()
+to create a new semaphore set or retrieve the ID of an existing set.
+It generates the
+.I key
+for
+.BR semget ()
+using
+.BR ftok (3).
+The first two command-line arguments are used as the
+.I pathname
+and
+.I proj_id
+arguments for
+.BR ftok (3).
+The third command-line argument is an integer that specifies the
+.I nsems
+argument for
+.BR semget ().
+Command-line options can be used to specify the
+.B IPC_CREAT
+.RI ( \-c )
+and
+.B IPC_EXCL
+.RI ( \-x )
+flags for the call to
+.BR semget ().
+The usage of this program is demonstrated below.
+.P
+We first create two files that will be used to generate keys using
+.BR ftok (3),
+create two semaphore sets using those files, and then list the sets using
+.BR ipcs (1):
+.P
+.in +4n
+.EX
+$ \fBtouch mykey mykey2\fP
+$ \fB./t_semget \-c mykey p 1\fP
+ID = 9
+$ \fB./t_semget \-c mykey2 p 2\fP
+ID = 10
+$ \fBipcs \-s\fP
+\&
+\-\-\-\-\-\- Semaphore Arrays \-\-\-\-\-\-\-\-
+key        semid      owner      perms      nsems
+0x7004136d 9          mtk        600        1
+0x70041368 10         mtk        600        2
+.EE
+.in
+.P
+Next, we demonstrate that when
+.BR semctl (2)
+is given the same
+.I key
+(as generated by the same arguments to
+.BR ftok (3)),
+it returns the ID of the already existing semaphore set:
+.P
+.in +4n
+.EX
+$ \fB./t_semget \-c mykey p 1\fP
+ID = 9
+.EE
+.in
+.P
+Finally, we demonstrate the kind of collision that can occur when
+.BR ftok (3)
+is given different
+.I pathname
+arguments that have the same inode number:
+.P
+.in +4n
+.EX
+$ \fBln mykey link\fP
+$ \fBls \-i1 link mykey\fP
+2233197 link
+2233197 mykey
+$ \fB./t_semget link p 1\fP       # Generates same key as \[aq]mykey\[aq]
+ID = 9
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (t_semget.c)
+.EX
+/* t_semget.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#include <unistd.h>
+\&
+static void
+usage(const char *pname)
+{
+    fprintf(stderr, "Usage: %s [\-cx] pathname proj\-id num\-sems\en",
+            pname);
+    fprintf(stderr, "    \-c           Use IPC_CREAT flag\en");
+    fprintf(stderr, "    \-x           Use IPC_EXCL flag\en");
+    exit(EXIT_FAILURE);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int    semid, nsems, flags, opt;
+    key_t  key;
+\&
+    flags = 0;
+    while ((opt = getopt(argc, argv, "cx")) != \-1) {
+        switch (opt) {
+        case \[aq]c\[aq]: flags |= IPC_CREAT;   break;
+        case \[aq]x\[aq]: flags |= IPC_EXCL;    break;
+        default:  usage(argv[0]);
+        }
+    }
+\&
+    if (argc != optind + 3)
+        usage(argv[0]);
+\&
+    key = ftok(argv[optind], argv[optind + 1][0]);
+    if (key == \-1) {
+        perror("ftok");
+        exit(EXIT_FAILURE);
+    }
+\&
+    nsems = atoi(argv[optind + 2]);
+\&
+    semid = semget(key, nsems, flags | 0600);
+    if (semid == \-1) {
+        perror("semget");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("ID = %d\en", semid);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR semctl (2),
+.BR semop (2),
+.BR ftok (3),
+.BR capabilities (7),
+.BR sem_overview (7),
+.BR sysvipc (7)
diff --git a/man/man2/semop.2 b/man/man2/semop.2
new file mode 100644
index 000000000..92bfec80a
--- /dev/null
+++ b/man/man2/semop.2
@@ -0,0 +1,523 @@
+.\" Copyright 1993 Giorgio Ciucci (giorgio@crcc.it)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1996-10-22, Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2002-01-08, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2003-04-28, Ernie Petrides <petrides@redhat.com>
+.\" Modified 2004-05-27, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Added notes on /proc files
+.\" 2005-04-08, mtk, Noted kernel version numbers for semtimedop()
+.\" 2007-07-09, mtk, Added an EXAMPLE code segment.
+.\"
+.TH semop 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+semop, semtimedop \- System V semaphore operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/sem.h>
+.P
+.BI "int semop(int " semid ", struct sembuf *" sops ", size_t " nsops );
+.BI "int semtimedop(int " semid ", struct sembuf *" sops ", size_t " nsops ,
+.BI "               const struct timespec *_Nullable " timeout );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR semtimedop ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+Each semaphore in a System\ V semaphore set
+has the following associated values:
+.P
+.in +4n
+.EX
+unsigned short  semval;   /* semaphore value */
+unsigned short  semzcnt;  /* # waiting for zero */
+unsigned short  semncnt;  /* # waiting for increase */
+pid_t           sempid;   /* PID of process that last
+                             modified the semaphore value */
+.EE
+.in
+.P
+.BR semop ()
+performs operations on selected semaphores in the set indicated by
+.IR semid .
+Each of the
+.I nsops
+elements in the array pointed to by
+.I sops
+is a structure that
+specifies an operation to be performed on a single semaphore.
+The elements of this structure are of type
+.IR "struct sembuf" ,
+containing the following members:
+.P
+.in +4n
+.EX
+unsigned short sem_num;  /* semaphore number */
+short          sem_op;   /* semaphore operation */
+short          sem_flg;  /* operation flags */
+.EE
+.in
+.P
+Flags recognized in
+.I sem_flg
+are
+.B IPC_NOWAIT
+and
+.BR SEM_UNDO .
+If an operation specifies
+.BR SEM_UNDO ,
+it will be automatically undone when the process terminates.
+.P
+The set of operations contained in
+.I sops
+is performed in
+.IR "array order" ,
+and
+.IR atomically ,
+that is, the operations are performed either as a complete unit,
+or not at all.
+The behavior of the system call if not all operations can be
+performed immediately depends on the presence of the
+.B IPC_NOWAIT
+flag in the individual
+.I sem_flg
+fields, as noted below.
+.P
+Each operation is performed on the
+.IR sem_num \-th
+semaphore of the semaphore set, where the first semaphore of the set
+is numbered 0.
+There are three types of operation, distinguished by the value of
+.IR sem_op .
+.P
+If
+.I sem_op
+is a positive integer, the operation adds this value to
+the semaphore value
+.RI  ( semval ).
+Furthermore, if
+.B SEM_UNDO
+is specified for this operation, the system subtracts the value
+.I sem_op
+from the semaphore adjustment
+.RI ( semadj )
+value for this semaphore.
+This operation can always proceed\[em]it never forces a thread to wait.
+The calling process must have alter permission on the semaphore set.
+.P
+If
+.I sem_op
+is zero, the process must have read permission on the semaphore
+set.
+This is a "wait-for-zero" operation: if
+.I semval
+is zero, the operation can immediately proceed.
+Otherwise, if
+.B IPC_NOWAIT
+is specified in
+.IR sem_flg ,
+.BR semop ()
+fails with
+.I errno
+set to
+.B EAGAIN
+(and none of the operations in
+.I sops
+is performed).
+Otherwise,
+.I semzcnt
+(the count of threads waiting until this semaphore's value becomes zero)
+is incremented by one and the thread sleeps until
+one of the following occurs:
+.IP \[bu] 3
+.I semval
+becomes 0, at which time the value of
+.I semzcnt
+is decremented.
+.IP \[bu]
+The semaphore set
+is removed:
+.BR semop ()
+fails, with
+.I errno
+set to
+.BR EIDRM .
+.IP \[bu]
+The calling thread catches a signal:
+the value of
+.I semzcnt
+is decremented and
+.BR semop ()
+fails, with
+.I errno
+set to
+.BR EINTR .
+.P
+If
+.I sem_op
+is less than zero, the process must have alter permission on the
+semaphore set.
+If
+.I semval
+is greater than or equal to the absolute value of
+.IR sem_op ,
+the operation can proceed immediately:
+the absolute value of
+.I sem_op
+is subtracted from
+.IR semval ,
+and, if
+.B SEM_UNDO
+is specified for this operation, the system adds the absolute value of
+.I sem_op
+to the semaphore adjustment
+.RI ( semadj )
+value for this semaphore.
+If the absolute value of
+.I sem_op
+is greater than
+.IR semval ,
+and
+.B IPC_NOWAIT
+is specified in
+.IR sem_flg ,
+.BR semop ()
+fails, with
+.I errno
+set to
+.B EAGAIN
+(and none of the operations in
+.I sops
+is performed).
+Otherwise,
+.I semncnt
+(the counter of threads waiting for this semaphore's value to increase)
+is incremented by one and the thread sleeps until
+one of the following occurs:
+.IP \[bu] 3
+.I semval
+becomes greater than or equal to the absolute value of
+.IR sem_op :
+the operation now proceeds, as described above.
+.IP \[bu]
+The semaphore set is removed from the system:
+.BR semop ()
+fails, with
+.I errno
+set to
+.BR EIDRM .
+.IP \[bu]
+The calling thread catches a signal:
+the value of
+.I semncnt
+is decremented and
+.BR semop ()
+fails, with
+.I errno
+set to
+.BR EINTR .
+.P
+On successful completion, the
+.I sempid
+value for each semaphore specified in the array pointed to by
+.I sops
+is set to the caller's process ID.
+In addition, the
+.I sem_otime
+.\" and
+.\" .I sem_ctime
+is set to the current time.
+.SS semtimedop()
+.BR semtimedop ()
+behaves identically to
+.BR semop ()
+except that in those cases where the calling thread would sleep,
+the duration of that sleep is limited by the amount of elapsed
+time specified by the
+.I timespec
+structure whose address is passed in the
+.I timeout
+argument.
+(This sleep interval will be rounded up to the system clock granularity,
+and kernel scheduling delays mean that the interval
+may overrun by a small amount.)
+If the specified time limit has been reached,
+.BR semtimedop ()
+fails with
+.I errno
+set to
+.B EAGAIN
+(and none of the operations in
+.I sops
+is performed).
+If the
+.I timeout
+argument is NULL,
+then
+.BR semtimedop ()
+behaves exactly like
+.BR semop ().
+.P
+Note that if
+.BR semtimedop ()
+is interrupted by a signal, causing the call to fail with the error
+.BR EINTR ,
+the contents of
+.I timeout
+are left unchanged.
+.SH RETURN VALUE
+On success,
+.BR semop ()
+and
+.BR semtimedop ()
+return 0.
+On failure, they return \-1, and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B E2BIG
+The argument
+.I nsops
+is greater than
+.BR SEMOPM ,
+the maximum number of operations allowed per system
+call.
+.TP
+.B EACCES
+The calling process does not have the permissions required
+to perform the specified semaphore operations,
+and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EAGAIN
+An operation could not proceed immediately and either
+.B IPC_NOWAIT
+was specified in
+.I sem_flg
+or the time limit specified in
+.I timeout
+expired.
+.TP
+.B EFAULT
+An address specified in either the
+.I sops
+or the
+.I timeout
+argument isn't accessible.
+.TP
+.B EFBIG
+For some operation the value of
+.I sem_num
+is less than 0 or greater than or equal to the number
+of semaphores in the set.
+.TP
+.B EIDRM
+The semaphore set was removed.
+.TP
+.B EINTR
+While blocked in this system call, the thread caught a signal; see
+.BR signal (7).
+.TP
+.B EINVAL
+The semaphore set doesn't exist, or
+.I semid
+is less than zero, or
+.I nsops
+has a nonpositive value.
+.TP
+.B ENOMEM
+The
+.I sem_flg
+of some operation specified
+.B SEM_UNDO
+and the system does not have enough memory to allocate the undo
+structure.
+.TP
+.B ERANGE
+For some operation
+.I sem_op+semval
+is greater than
+.BR SEMVMX ,
+the implementation dependent maximum value for
+.IR semval .
+.SH STANDARDS
+POSIX.1-2008.
+.SH VERSIONS
+Linux 2.5.52 (backported into Linux 2.4.22),
+glibc 2.3.3.
+POSIX.1-2001, SVr4.
+.\" SVr4 documents additional error conditions EINVAL, EFBIG, ENOSPC.
+.SH NOTES
+The
+.I sem_undo
+structures of a process aren't inherited by the child produced by
+.BR fork (2),
+but they are inherited across an
+.BR execve (2)
+system call.
+.P
+.BR semop ()
+is never automatically restarted after being interrupted by a signal handler,
+regardless of the setting of the
+.B SA_RESTART
+flag when establishing a signal handler.
+.P
+A semaphore adjustment
+.RI ( semadj )
+value is a per-process, per-semaphore integer that is the negated sum
+of all operations performed on a semaphore specifying the
+.B SEM_UNDO
+flag.
+Each process has a list of
+.I semadj
+values\[em]one value for each semaphore on which it has operated using
+.BR SEM_UNDO .
+When a process terminates, each of its per-semaphore
+.I semadj
+values is added to the corresponding semaphore,
+thus undoing the effect of that process's operations on the semaphore
+(but see BUGS below).
+When a semaphore's value is directly set using the
+.B SETVAL
+or
+.B SETALL
+request to
+.BR semctl (2),
+the corresponding
+.I semadj
+values in all processes are cleared.
+The
+.BR clone (2)
+.B CLONE_SYSVSEM
+flag allows more than one process to share a
+.I semadj
+list; see
+.BR clone (2)
+for details.
+.P
+The \fIsemval\fP, \fIsempid\fP, \fIsemzcnt\fP, and \fIsemnct\fP values
+for a semaphore can all be retrieved using appropriate
+.BR semctl (2)
+calls.
+.SS Semaphore limits
+The following limits on semaphore set resources affect the
+.BR semop ()
+call:
+.TP
+.B SEMOPM
+Maximum number of operations allowed for one
+.BR semop ()
+call.
+Before Linux 3.19,
+.\" commit e843e7d2c88b7db107a86bd2c7145dc715c058f4
+the default value for this limit was 32.
+Since Linux 3.19, the default value is 500.
+On Linux, this limit can be read and modified via the third field of
+.IR /proc/sys/kernel/sem .
+.\" This /proc file is not available in Linux 2.2 and earlier -- MTK
+.IR Note :
+this limit should not be raised above 1000,
+.\" See comment in Linux 3.19 source file include/uapi/linux/sem.h
+because of the risk of that
+.BR semop ()
+fails due to kernel memory fragmentation when allocating memory to copy the
+.I sops
+array.
+.TP
+.B SEMVMX
+Maximum allowable value for
+.IR semval :
+implementation dependent (32767).
+.P
+The implementation has no intrinsic limits for
+the adjust on exit maximum value
+.RB ( SEMAEM ),
+the system wide maximum number of undo structures
+.RB ( SEMMNU )
+and the per-process maximum number of undo entries system parameters.
+.SH BUGS
+When a process terminates, its set of associated
+.I semadj
+structures is used to undo the effect of all of the
+semaphore operations it performed with the
+.B SEM_UNDO
+flag.
+This raises a difficulty: if one (or more) of these semaphore adjustments
+would result in an attempt to decrease a semaphore's value below zero,
+what should an implementation do?
+One possible approach would be to block until all the semaphore
+adjustments could be performed.
+This is however undesirable since it could force process termination to
+block for arbitrarily long periods.
+Another possibility is that such semaphore adjustments could be ignored
+altogether (somewhat analogously to failing when
+.B IPC_NOWAIT
+is specified for a semaphore operation).
+Linux adopts a third approach: decreasing the semaphore value
+as far as possible (i.e., to zero) and allowing process
+termination to proceed immediately.
+.P
+In Linux 2.6.x, x <= 10, there is a bug that in some circumstances
+prevents a thread that is waiting for a semaphore value to become
+zero from being woken up when the value does actually become zero.
+This bug is fixed in Linux 2.6.11.
+.\" The bug report:
+.\" http://marc.theaimsgroup.com/?l=linux-kernel&m=110260821123863&w=2
+.\" the fix:
+.\" http://marc.theaimsgroup.com/?l=linux-kernel&m=110261701025794&w=2
+.SH EXAMPLES
+The following code segment uses
+.BR semop ()
+to atomically wait for the value of semaphore 0 to become zero,
+and then increment the semaphore value by one.
+.P
+.in +4n
+.EX
+struct sembuf sops[2];
+int semid;
+\&
+/* Code to set \fIsemid\fP omitted */
+\&
+sops[0].sem_num = 0;        /* Operate on semaphore 0 */
+sops[0].sem_op = 0;         /* Wait for value to equal 0 */
+sops[0].sem_flg = 0;
+\&
+sops[1].sem_num = 0;        /* Operate on semaphore 0 */
+sops[1].sem_op = 1;         /* Increment value by one */
+sops[1].sem_flg = 0;
+\&
+if (semop(semid, sops, 2) == \-1) {
+    perror("semop");
+    exit(EXIT_FAILURE);
+}
+.EE
+.in
+.P
+A further example of the use of
+.BR semop ()
+can be found in
+.BR shmop (2).
+.SH SEE ALSO
+.BR clone (2),
+.BR semctl (2),
+.BR semget (2),
+.BR sigaction (2),
+.BR capabilities (7),
+.BR sem_overview (7),
+.BR sysvipc (7),
+.BR time (7)
diff --git a/man/man2/semtimedop.2 b/man/man2/semtimedop.2
new file mode 100644
index 000000000..8a4061874
--- /dev/null
+++ b/man/man2/semtimedop.2
@@ -0,0 +1 @@
+.so man2/semop.2
diff --git a/man/man2/send.2 b/man/man2/send.2
new file mode 100644
index 000000000..f3de06e4c
--- /dev/null
+++ b/man/man2/send.2
@@ -0,0 +1,506 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Oct 1998 by Andi Kleen
+.\" Modified Oct 2003 by aeb
+.\" Modified 2004-07-01 by mtk
+.\"
+.TH send 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+send, sendto, sendmsg \- send a message on a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "ssize_t send(int " sockfd ", const void " buf [. len "], size_t " len \
+", int " flags );
+.BI "ssize_t sendto(int " sockfd ", const void " buf [. len "], size_t " len \
+", int " flags ,
+.BI "               const struct sockaddr *" dest_addr ", socklen_t " addrlen );
+.BI "ssize_t sendmsg(int " sockfd ", const struct msghdr *" msg \
+", int " flags );
+.fi
+.SH DESCRIPTION
+The system calls
+.BR send (),
+.BR sendto (),
+and
+.BR sendmsg ()
+are used to transmit a message to another socket.
+.P
+The
+.BR send ()
+call may be used only when the socket is in a
+.I connected
+state (so that the intended recipient is known).
+The only difference between
+.BR send ()
+and
+.BR write (2)
+is the presence of
+.IR flags .
+With a zero
+.I flags
+argument,
+.BR send ()
+is equivalent to
+.BR write (2).
+Also, the following call
+.P
+.in +4n
+.EX
+send(sockfd, buf, len, flags);
+.EE
+.in
+.P
+is equivalent to
+.P
+.in +4n
+.EX
+sendto(sockfd, buf, len, flags, NULL, 0);
+.EE
+.in
+.P
+The argument
+.I sockfd
+is the file descriptor of the sending socket.
+.P
+If
+.BR sendto ()
+is used on a connection-mode
+.RB ( SOCK_STREAM ,
+.BR SOCK_SEQPACKET )
+socket, the arguments
+.I dest_addr
+and
+.I addrlen
+are ignored (and the error
+.B EISCONN
+may be returned when they are
+not NULL and 0), and the error
+.B ENOTCONN
+is returned when the socket was not actually connected.
+Otherwise, the address of the target is given by
+.I dest_addr
+with
+.I addrlen
+specifying its size.
+For
+.BR sendmsg (),
+the address of the target is given by
+.IR msg.msg_name ,
+with
+.I msg.msg_namelen
+specifying its size.
+.P
+For
+.BR send ()
+and
+.BR sendto (),
+the message is found in
+.I buf
+and has length
+.IR len .
+For
+.BR sendmsg (),
+the message is pointed to by the elements of the array
+.IR msg.msg_iov .
+The
+.BR sendmsg ()
+call also allows sending ancillary data (also known as control information).
+.P
+If the message is too long to pass atomically through the
+underlying protocol, the error
+.B EMSGSIZE
+is returned, and the message is not transmitted.
+.P
+No indication of failure to deliver is implicit in a
+.BR send ().
+Locally detected errors are indicated by a return value of \-1.
+.P
+When the message does not fit into the send buffer of the socket,
+.BR send ()
+normally blocks, unless the socket has been placed in nonblocking I/O
+mode.
+In nonblocking mode it would fail with the error
+.B EAGAIN
+or
+.B EWOULDBLOCK
+in this case.
+The
+.BR select (2)
+call may be used to determine when it is possible to send more data.
+.SS The flags argument
+The
+.I flags
+argument is the bitwise OR
+of zero or more of the following flags.
+.\" FIXME . ? document MSG_PROXY (which went away in Linux 2.3.15)
+.TP
+.BR MSG_CONFIRM " (since Linux 2.3.15)"
+Tell the link layer that forward progress happened: you got a successful
+reply from the other side.
+If the link layer doesn't get this
+it will regularly reprobe the neighbor (e.g., via a unicast ARP).
+Valid only on
+.B SOCK_DGRAM
+and
+.B SOCK_RAW
+sockets and currently implemented only for IPv4 and IPv6.
+See
+.BR arp (7)
+for details.
+.TP
+.B MSG_DONTROUTE
+Don't use a gateway to send out the packet, send to hosts only on
+directly connected networks.
+This is usually used only
+by diagnostic or routing programs.
+This is defined only for protocol
+families that route; packet sockets don't.
+.TP
+.BR MSG_DONTWAIT " (since Linux 2.2)"
+Enables nonblocking operation; if the operation would block,
+.B EAGAIN
+or
+.B EWOULDBLOCK
+is returned.
+This provides similar behavior to setting the
+.B O_NONBLOCK
+flag (via the
+.BR fcntl (2)
+.B F_SETFL
+operation), but differs in that
+.B MSG_DONTWAIT
+is a per-call option, whereas
+.B O_NONBLOCK
+is a setting on the open file description (see
+.BR open (2)),
+which will affect all threads in the calling process
+as well as other processes that hold file descriptors
+referring to the same open file description.
+.TP
+.BR MSG_EOR " (since Linux 2.2)"
+Terminates a record (when this notion is supported, as for sockets of type
+.BR SOCK_SEQPACKET ).
+.TP
+.BR MSG_MORE " (since Linux 2.4.4)"
+The caller has more data to send.
+This flag is used with TCP sockets to obtain the same effect
+as the
+.B TCP_CORK
+socket option (see
+.BR tcp (7)),
+with the difference that this flag can be set on a per-call basis.
+.IP
+Since Linux 2.6, this flag is also supported for UDP sockets, and informs
+the kernel to package all of the data sent in calls with this flag set
+into a single datagram which is transmitted only when a call is performed
+that does not specify this flag.
+(See also the
+.B UDP_CORK
+socket option described in
+.BR udp (7).)
+.TP
+.BR MSG_NOSIGNAL " (since Linux 2.2)"
+Don't generate a
+.B SIGPIPE
+signal if the peer on a stream-oriented socket has closed the connection.
+The
+.B EPIPE
+error is still returned.
+This provides similar behavior to using
+.BR sigaction (2)
+to ignore
+.BR SIGPIPE ,
+but, whereas
+.B MSG_NOSIGNAL
+is a per-call feature,
+ignoring
+.B SIGPIPE
+sets a process attribute that affects all threads in the process.
+.TP
+.B MSG_OOB
+Sends
+.I out-of-band
+data on sockets that support this notion (e.g., of type
+.BR SOCK_STREAM );
+the underlying protocol must also support
+.I out-of-band
+data.
+.TP
+.BR MSG_FASTOPEN " (since Linux 3.7)"
+Attempts TCP Fast Open (RFC7413) and sends data in the SYN like a
+combination of
+.BR connect (2)
+and
+.BR write (2),
+by performing an implicit
+.BR connect (2)
+operation.
+It blocks until the data is buffered and the handshake has completed.
+For a non-blocking socket,
+it returns the number of bytes buffered and sent in the SYN packet.
+If the cookie is not available locally,
+it returns
+.BR EINPROGRESS ,
+and sends a SYN with a Fast Open cookie request automatically.
+The caller needs to write the data again when the socket is connected.
+On errors,
+it sets the same
+.I errno
+as
+.BR connect (2)
+if the handshake fails.
+This flag requires enabling TCP Fast Open client support on sysctl
+.IR net.ipv4.tcp_fastopen .
+.IP
+Refer to
+.B TCP_FASTOPEN_CONNECT
+socket option in
+.BR tcp (7)
+for an alternative approach.
+.SS sendmsg()
+The definition of the
+.I msghdr
+structure employed by
+.BR sendmsg ()
+is as follows:
+.P
+.in +4n
+.EX
+struct msghdr {
+    void         *msg_name;       /* Optional address */
+    socklen_t     msg_namelen;    /* Size of address */
+    struct iovec *msg_iov;        /* Scatter/gather array */
+    size_t        msg_iovlen;     /* # elements in msg_iov */
+    void         *msg_control;    /* Ancillary data, see below */
+    size_t        msg_controllen; /* Ancillary data buffer len */
+    int           msg_flags;      /* Flags (unused) */
+};
+.EE
+.in
+.P
+The
+.I msg_name
+field is used on an unconnected socket to specify the target
+address for a datagram.
+It points to a buffer containing the address; the
+.I msg_namelen
+field should be set to the size of the address.
+For a connected socket, these fields should be specified as NULL and 0,
+respectively.
+.P
+The
+.I msg_iov
+and
+.I msg_iovlen
+fields specify scatter-gather locations, as for
+.BR writev (2).
+.P
+You may send control information (ancillary data) using the
+.I msg_control
+and
+.I msg_controllen
+members.
+The maximum control buffer length the kernel can process is limited
+per socket by the value in
+.IR /proc/sys/net/core/optmem_max ;
+see
+.BR socket (7).
+For further information on the use of ancillary data in various
+socket domains, see
+.BR unix (7)
+and
+.BR ip (7).
+.P
+The
+.I msg_flags
+field is ignored.
+.\" Still to be documented:
+.\"  Send file descriptors and user credentials using the
+.\"  msg_control* fields.
+.SH RETURN VALUE
+On success, these calls return the number of bytes sent.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+These are some standard errors generated by the socket layer.
+Additional errors
+may be generated and returned from the underlying protocol modules;
+see their respective manual pages.
+.TP
+.B EACCES
+(For UNIX domain sockets, which are identified by pathname)
+Write permission is denied on the destination socket file,
+or search permission is denied for one of the directories
+the path prefix.
+(See
+.BR path_resolution (7).)
+.IP
+(For UDP sockets) An attempt was made to send to a
+network/broadcast address as though it was a unicast address.
+.TP
+.BR EAGAIN " or " EWOULDBLOCK
+.\" Actually EAGAIN on Linux
+The socket is marked nonblocking and the requested operation
+would block.
+POSIX.1-2001 allows either error to be returned for this case,
+and does not require these constants to have the same value,
+so a portable application should check for both possibilities.
+.TP
+.B EAGAIN
+(Internet domain datagram sockets)
+The socket referred to by
+.I sockfd
+had not previously been bound to an address and,
+upon attempting to bind it to an ephemeral port,
+it was determined that all port numbers in the ephemeral port range
+are currently in use.
+See the discussion of
+.I /proc/sys/net/ipv4/ip_local_port_range
+in
+.BR ip (7).
+.TP
+.B EALREADY
+Another Fast Open is in progress.
+.TP
+.B EBADF
+.I sockfd
+is not a valid open file descriptor.
+.TP
+.B ECONNRESET
+Connection reset by peer.
+.TP
+.B EDESTADDRREQ
+The socket is not connection-mode, and no peer address is set.
+.TP
+.B EFAULT
+An invalid user space address was specified for an argument.
+.TP
+.B EINTR
+A signal occurred before any data was transmitted; see
+.BR signal (7).
+.TP
+.B EINVAL
+Invalid argument passed.
+.TP
+.B EISCONN
+The connection-mode socket was connected already but a
+recipient was specified.
+(Now either this error is returned, or the recipient specification
+is ignored.)
+.TP
+.B EMSGSIZE
+The socket type
+.\" (e.g., SOCK_DGRAM )
+requires that message be sent atomically, and the size
+of the message to be sent made this impossible.
+.TP
+.B ENOBUFS
+The output queue for a network interface was full.
+This generally indicates that the interface has stopped sending,
+but may be caused by transient congestion.
+(Normally, this does not occur in Linux.
+Packets are just silently dropped
+when a device queue overflows.)
+.TP
+.B ENOMEM
+No memory available.
+.TP
+.B ENOTCONN
+The socket is not connected, and no target has been given.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.TP
+.B EOPNOTSUPP
+Some bit in the
+.I flags
+argument is inappropriate for the socket type.
+.TP
+.B EPIPE
+The local end has been shut down on a connection oriented socket.
+In this case, the process
+will also receive a
+.B SIGPIPE
+unless
+.B MSG_NOSIGNAL
+is set.
+.SH VERSIONS
+According to POSIX.1-2001, the
+.I msg_controllen
+field of the
+.I msghdr
+structure should be typed as
+.IR socklen_t ,
+and the
+.I msg_iovlen
+field should be typed as
+.IR int ,
+but glibc currently types both as
+.IR size_t .
+.\" glibc bug for msg_controllen raised 12 Mar 2006
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=2448
+.\" The problem is an underlying kernel issue: the size of the
+.\" __kernel_size_t type used to type these fields varies
+.\" across architectures, but socklen_t is always 32 bits,
+.\" as (at least with GCC) is int.
+.SH STANDARDS
+POSIX.1-2008.
+.P
+.B MSG_CONFIRM
+is a Linux extension.
+.SH HISTORY
+4.4BSD, SVr4, POSIX.1-2001.
+(first appeared in 4.2BSD).
+.P
+POSIX.1-2001 describes only the
+.B MSG_OOB
+and
+.B MSG_EOR
+flags.
+POSIX.1-2008 adds a specification of
+.BR MSG_NOSIGNAL .
+.SH NOTES
+See
+.BR sendmmsg (2)
+for information about a Linux-specific system call
+that can be used to transmit multiple datagrams in a single call.
+.SH BUGS
+Linux may return
+.B EPIPE
+instead of
+.BR ENOTCONN .
+.SH EXAMPLES
+An example of the use of
+.BR sendto ()
+is shown in
+.BR getaddrinfo (3).
+.SH SEE ALSO
+.BR fcntl (2),
+.BR getsockopt (2),
+.BR recv (2),
+.BR select (2),
+.BR sendfile (2),
+.BR sendmmsg (2),
+.BR shutdown (2),
+.BR socket (2),
+.BR write (2),
+.BR cmsg (3),
+.BR ip (7),
+.BR ipv6 (7),
+.BR socket (7),
+.BR tcp (7),
+.BR udp (7),
+.BR unix (7)
diff --git a/man/man2/sendfile.2 b/man/man2/sendfile.2
new file mode 100644
index 000000000..a385949c1
--- /dev/null
+++ b/man/man2/sendfile.2
@@ -0,0 +1,245 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1998 Pawel Krawczyk.
+.\"
+.\" $Id: sendfile.2,v 1.5 1999/05/18 11:54:11 freitag Exp $
+.\" 2000-11-19 bert hubert <ahu@ds9a.nl>: in_fd cannot be socket
+.\"
+.\" 2004-12-17, mtk
+.\"	updated description of in_fd and out_fd for 2.6
+.\"	Various wording and formatting changes
+.\"
+.\" 2005-03-31 Martin Pool <mbp@sourcefrog.net> mmap() improvements
+.\"
+.TH sendfile 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sendfile \- transfer data between file descriptors
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/sendfile.h>
+.P
+.BI "ssize_t sendfile(int" " out_fd" ", int" " in_fd" ", \
+off_t *_Nullable " offset ,
+.BI "                 size_t" " count" );
+.\" The below is too ugly. Comments about glibc versions belong
+.\" in the notes, not in the header.
+.\"
+.\" .B #include <features.h>
+.\" .B #if (__GLIBC__==2 && __GLIBC_MINOR__>=1) || __GLIBC__>2
+.\" .B #include <sys/sendfile.h>
+.\" #else
+.\" .B #include <sys/types.h>
+.\" .B /* No system prototype before glibc 2.1. */
+.\" .BI "ssize_t sendfile(int" " out_fd" ", int" " in_fd" ", off_t *" \
+.\"                       offset ", size_t" " count" )
+.\" .B #endif
+.\"
+.fi
+.SH DESCRIPTION
+.BR sendfile ()
+copies data between one file descriptor and another.
+Because this copying is done within the kernel,
+.BR sendfile ()
+is more efficient than the combination of
+.BR read (2)
+and
+.BR write (2),
+which would require transferring data to and from user space.
+.P
+.I in_fd
+should be a file descriptor opened for reading and
+.I out_fd
+should be a descriptor opened for writing.
+.P
+If
+.I offset
+is not NULL, then it points
+to a variable holding the file offset from which
+.BR sendfile ()
+will start reading data from
+.IR in_fd .
+When
+.BR sendfile ()
+returns, this variable
+will be set to the offset of the byte following the last byte that was read.
+If
+.I offset
+is not NULL, then
+.BR sendfile ()
+does not modify the file offset of
+.IR in_fd ;
+otherwise the file offset is adjusted to reflect
+the number of bytes read from
+.IR in_fd .
+.P
+If
+.I offset
+is NULL, then data will be read from
+.I in_fd
+starting at the file offset,
+and the file offset will be updated by the call.
+.P
+.I count
+is the number of bytes to copy between the file descriptors.
+.P
+The
+.I in_fd
+argument must correspond to a file which supports
+.BR mmap (2)-like
+operations
+(i.e., it cannot be a socket).
+Except since Linux 5.12
+.\" commit b964bf53e540262f2d12672b3cca10842c0172e7
+and if
+.I out_fd
+is a pipe, in which case
+.BR sendfile ()
+desugars to a
+.BR splice (2)
+and its restrictions apply.
+.P
+Before Linux 2.6.33,
+.I out_fd
+must refer to a socket.
+Since Linux 2.6.33 it can be any file.
+If it's seekable, then
+.BR sendfile ()
+changes the file offset appropriately.
+.SH RETURN VALUE
+If the transfer was successful, the number of bytes written to
+.I out_fd
+is returned.
+Note that a successful call to
+.BR sendfile ()
+may write fewer bytes than requested;
+the caller should be prepared to retry the call if there were unsent bytes.
+See also NOTES.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+Nonblocking I/O has been selected using
+.B O_NONBLOCK
+and the write would block.
+.TP
+.B EBADF
+The input file was not opened for reading or the output file
+was not opened for writing.
+.TP
+.B EFAULT
+Bad address.
+.TP
+.B EINVAL
+Descriptor is not valid or locked, or an
+.BR mmap (2)-like
+operation is not available for
+.IR in_fd ,
+or
+.I count
+is negative.
+.TP
+.B EINVAL
+.I out_fd
+has the
+.B O_APPEND
+flag set.
+This is not currently supported by
+.BR sendfile ().
+.TP
+.B EIO
+Unspecified error while reading from
+.IR in_fd .
+.TP
+.B ENOMEM
+Insufficient memory to read from
+.IR in_fd .
+.TP
+.B EOVERFLOW
+.I count
+is too large, the operation would result in exceeding the maximum size of either
+the input file or the output file.
+.TP
+.B ESPIPE
+.I offset
+is not NULL but the input file is not seekable.
+.SH VERSIONS
+Other UNIX systems implement
+.BR sendfile ()
+with different semantics and prototypes.
+It should not be used in portable programs.
+.SH STANDARDS
+None.
+.SH HISTORY
+Linux 2.2,
+glibc 2.1.
+.P
+In Linux 2.4 and earlier,
+.I out_fd
+could also refer to a regular file;
+this possibility went away in the Linux 2.6.x kernel series,
+but was restored in Linux 2.6.33.
+.P
+The original Linux
+.BR sendfile ()
+system call was not designed to handle large file offsets.
+Consequently, Linux 2.4 added
+.BR sendfile64 (),
+with a wider type for the
+.I offset
+argument.
+The glibc
+.BR sendfile ()
+wrapper function transparently deals with the kernel differences.
+.SH NOTES
+.BR sendfile ()
+will transfer at most 0x7ffff000 (2,147,479,552) bytes,
+returning the number of bytes actually transferred.
+.\" commit e28cc71572da38a5a12c1cfe4d7032017adccf69
+(This is true on both 32-bit and 64-bit systems.)
+.P
+If you plan to use
+.BR sendfile ()
+for sending files to a TCP socket, but need
+to send some header data in front of the file contents, you will find
+it useful to employ the
+.B TCP_CORK
+option, described in
+.BR tcp (7),
+to minimize the number of packets and to tune performance.
+.P
+Applications may wish to fall back to
+.BR read (2)
+and
+.BR write (2)
+in the case where
+.BR sendfile ()
+fails with
+.B EINVAL
+or
+.BR ENOSYS .
+.P
+If
+.I out_fd
+refers to a socket or pipe with zero-copy support, callers must ensure the
+transferred portions of the file referred to by
+.I in_fd
+remain unmodified until the reader on the other end of
+.I out_fd
+has consumed the transferred data.
+.P
+The Linux-specific
+.BR splice (2)
+call supports transferring data between arbitrary file descriptors
+provided one (or both) of them is a pipe.
+.SH SEE ALSO
+.BR copy_file_range (2),
+.BR mmap (2),
+.BR open (2),
+.BR socket (2),
+.BR splice (2)
diff --git a/man/man2/sendfile64.2 b/man/man2/sendfile64.2
new file mode 100644
index 000000000..888077b1a
--- /dev/null
+++ b/man/man2/sendfile64.2
@@ -0,0 +1 @@
+.so man2/sendfile.2
diff --git a/man/man2/sendmmsg.2 b/man/man2/sendmmsg.2
new file mode 100644
index 000000000..bc541aae5
--- /dev/null
+++ b/man/man2/sendmmsg.2
@@ -0,0 +1,232 @@
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" with some material from a draft by
+.\" Stephan Mueller <stephan.mueller@atsec.com>
+.\" in turn based on Andi Kleen's recvmmsg.2 page.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sendmmsg 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sendmmsg \- send multiple messages on a socket
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <sys/socket.h>
+.P
+.BI "int sendmmsg(int " sockfd ", struct mmsghdr *" msgvec \
+", unsigned int " vlen ","
+.BI "             int " flags ");"
+.fi
+.SH DESCRIPTION
+The
+.BR sendmmsg ()
+system call is an extension of
+.BR sendmsg (2)
+that allows the caller to transmit multiple messages on a socket
+using a single system call.
+(This has performance benefits for some applications.)
+.\" See commit 228e548e602061b08ee8e8966f567c12aa079682
+.P
+The
+.I sockfd
+argument is the file descriptor of the socket
+on which data is to be transmitted.
+.P
+The
+.I msgvec
+argument is a pointer to an array of
+.I mmsghdr
+structures.
+The size of this array is specified in
+.IR vlen .
+.P
+The
+.I mmsghdr
+structure is defined in
+.I <sys/socket.h>
+as:
+.P
+.in +4n
+.EX
+struct mmsghdr {
+    struct msghdr msg_hdr;  /* Message header */
+    unsigned int  msg_len;  /* Number of bytes transmitted */
+};
+.EE
+.in
+.P
+The
+.I msg_hdr
+field is a
+.I msghdr
+structure, as described in
+.BR sendmsg (2).
+The
+.I msg_len
+field is used to return the number of bytes sent from the message in
+.I msg_hdr
+(i.e., the same as the return value from a single
+.BR sendmsg (2)
+call).
+.P
+The
+.I flags
+argument contains flags ORed together.
+The flags are the same as for
+.BR sendmsg (2).
+.P
+A blocking
+.BR sendmmsg ()
+call blocks until
+.I vlen
+messages have been sent.
+A nonblocking call sends as many messages as possible
+(up to the limit specified by
+.IR vlen )
+and returns immediately.
+.P
+On return from
+.BR sendmmsg (),
+the
+.I msg_len
+fields of successive elements of
+.I msgvec
+are updated to contain the number of bytes transmitted from the corresponding
+.IR msg_hdr .
+The return value of the call indicates the number of elements of
+.I msgvec
+that have been updated.
+.SH RETURN VALUE
+On success,
+.BR sendmmsg ()
+returns the number of messages sent from
+.IR msgvec ;
+if this is less than
+.IR vlen ,
+the caller can retry with a further
+.BR sendmmsg ()
+call to send the remaining messages.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Errors are as for
+.BR sendmsg (2).
+An error is returned only if no datagrams could be sent.
+See also BUGS.
+.\" commit 728ffb86f10873aaf4abd26dde691ee40ae731fe
+.\"     ... only return an error if no datagrams could be sent.
+.\"     If less than the requested number of messages were sent, the application
+.\"     must retry starting at the first failed one and if the problem is
+.\"     persistent the error will be returned.
+.\"
+.\"     This matches the behavior of other syscalls like read/write - it
+.\"     is not an error if less than the requested number of elements are sent.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 3.0,
+glibc 2.14.
+.SH NOTES
+The value specified in
+.I vlen
+is capped to
+.B UIO_MAXIOV
+(1024).
+.\" commit 98382f419f32d2c12d021943b87dea555677144b
+.\"     net: Cap number of elements for sendmmsg
+.\"
+.\"     To limit the amount of time we can spend in sendmmsg, cap the
+.\"     number of elements to UIO_MAXIOV (currently 1024).
+.\"
+.\"     For error handling an application using sendmmsg needs to retry at
+.\"     the first unsent message, so capping is simpler and requires less
+.\"     application logic than returning EINVAL.
+.SH BUGS
+If an error occurs after at least one message has been sent,
+the call succeeds, and returns the number of messages sent.
+The error code is lost.
+The caller can retry the transmission,
+starting at the first failed message, but there is no guarantee that,
+if an error is returned, it will be the same as the one that was lost
+on the previous call.
+.SH EXAMPLES
+The example below uses
+.BR sendmmsg ()
+to send
+.I onetwo
+and
+.I three
+in two distinct UDP datagrams using one system call.
+The contents of the first datagram originates from a pair of buffers.
+.P
+.\" SRC BEGIN (sendmmsg.c)
+.EX
+#define _GNU_SOURCE
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+\&
+int
+main(void)
+{
+    int                 retval;
+    int                 sockfd;
+    struct iovec        msg1[2], msg2;
+    struct mmsghdr      msg[2];
+    struct sockaddr_in  addr;
+\&
+    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (sockfd == \-1) {
+        perror("socket()");
+        exit(EXIT_FAILURE);
+    }
+\&
+    addr.sin_family = AF_INET;
+    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+    addr.sin_port = htons(1234);
+    if (connect(sockfd, (struct sockaddr *) &addr, sizeof(addr)) == \-1) {
+        perror("connect()");
+        exit(EXIT_FAILURE);
+    }
+\&
+    memset(msg1, 0, sizeof(msg1));
+    msg1[0].iov_base = "one";
+    msg1[0].iov_len = 3;
+    msg1[1].iov_base = "two";
+    msg1[1].iov_len = 3;
+\&
+    memset(&msg2, 0, sizeof(msg2));
+    msg2.iov_base = "three";
+    msg2.iov_len = 5;
+\&
+    memset(msg, 0, sizeof(msg));
+    msg[0].msg_hdr.msg_iov = msg1;
+    msg[0].msg_hdr.msg_iovlen = 2;
+\&
+    msg[1].msg_hdr.msg_iov = &msg2;
+    msg[1].msg_hdr.msg_iovlen = 1;
+\&
+    retval = sendmmsg(sockfd, msg, 2, 0);
+    if (retval == \-1)
+        perror("sendmmsg()");
+    else
+        printf("%d messages sent\en", retval);
+\&
+    exit(0);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR recvmmsg (2),
+.BR sendmsg (2),
+.BR socket (2),
+.BR socket (7)
diff --git a/man/man2/sendmsg.2 b/man/man2/sendmsg.2
new file mode 100644
index 000000000..9a61b33bb
--- /dev/null
+++ b/man/man2/sendmsg.2
@@ -0,0 +1 @@
+.so man2/send.2
diff --git a/man/man2/sendto.2 b/man/man2/sendto.2
new file mode 100644
index 000000000..9a61b33bb
--- /dev/null
+++ b/man/man2/sendto.2
@@ -0,0 +1 @@
+.so man2/send.2
diff --git a/man/man2/set_mempolicy.2 b/man/man2/set_mempolicy.2
new file mode 100644
index 000000000..f1f225e32
--- /dev/null
+++ b/man/man2/set_mempolicy.2
@@ -0,0 +1,343 @@
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft-var
+.\"
+.\" Copyright 2003,2004 Andi Kleen, SuSE Labs.
+.\" and Copyright 2007 Lee Schermerhorn, Hewlett Packard
+.\"
+.\" 2006-02-03, mtk, substantial wording changes and other improvements
+.\" 2007-08-27, Lee Schermerhorn <Lee.Schermerhorn@hp.com>
+.\"     more precise specification of behavior.
+.\"
+.TH set_mempolicy 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+set_mempolicy \- set default NUMA memory policy for a thread and its children
+.SH LIBRARY
+NUMA (Non-Uniform Memory Access) policy library
+.RI ( libnuma ", " \-lnuma )
+.SH SYNOPSIS
+.nf
+.B "#include <numaif.h>"
+.P
+.BI "long set_mempolicy(int " mode ", const unsigned long *" nodemask ,
+.BI "                   unsigned long " maxnode );
+.fi
+.SH DESCRIPTION
+.BR set_mempolicy ()
+sets the NUMA memory policy of the calling thread,
+which consists of a policy mode and zero or more nodes,
+to the values specified by the
+.IR mode ,
+.IR nodemask ,
+and
+.I maxnode
+arguments.
+.P
+A NUMA machine has different
+memory controllers with different distances to specific CPUs.
+The memory policy defines from which node memory is allocated for
+the thread.
+.P
+This system call defines the default policy for the thread.
+The thread policy governs allocation of pages in the process's
+address space outside of memory ranges
+controlled by a more specific policy set by
+.BR mbind (2).
+The thread default policy also controls allocation of any pages for
+memory-mapped files mapped using the
+.BR mmap (2)
+call with the
+.B MAP_PRIVATE
+flag and that are only read (loaded) from by the thread
+and of memory-mapped files mapped using the
+.BR mmap (2)
+call with the
+.B MAP_SHARED
+flag, regardless of the access type.
+The policy is applied only when a new page is allocated
+for the thread.
+For anonymous memory this is when the page is first
+touched by the thread.
+.P
+The
+.I mode
+argument must specify one of
+.BR MPOL_DEFAULT ,
+.BR MPOL_BIND ,
+.BR MPOL_INTERLEAVE ,
+.BR MPOL_WEIGHTED_INTERLEAVE ,
+.BR MPOL_PREFERRED ,
+or
+.B MPOL_LOCAL
+(which are described in detail below).
+All modes except
+.B MPOL_DEFAULT
+require the caller to specify the node or nodes to which the mode applies,
+via the
+.I nodemask
+argument.
+.P
+The
+.I mode
+argument may also include an optional
+.IR "mode flag" .
+The supported
+.I "mode flags"
+are:
+.TP
+.BR MPOL_F_NUMA_BALANCING " (since Linux 5.12)"
+.\" commit bda420b985054a3badafef23807c4b4fa38a3dff
+When
+.I mode
+is
+.BR MPOL_BIND ,
+enable the kernel NUMA balancing for the task if it is supported by the kernel.
+If the flag isn't supported by the kernel, or is used with
+.I mode
+other than
+.BR MPOL_BIND ,
+\-1 is returned and
+.I errno
+is set to
+.BR EINVAL .
+.TP
+.BR MPOL_F_RELATIVE_NODES " (since Linux 2.6.26)"
+A nonempty
+.I nodemask
+specifies node IDs that are relative to the
+set of node IDs allowed by the process's current cpuset.
+.TP
+.BR MPOL_F_STATIC_NODES " (since Linux 2.6.26)"
+A nonempty
+.I nodemask
+specifies physical node IDs.
+Linux will not remap the
+.I nodemask
+when the process moves to a different cpuset context,
+nor when the set of nodes allowed by the process's
+current cpuset context changes.
+.P
+.I nodemask
+points to a bit mask of node IDs that contains up to
+.I maxnode
+bits.
+The bit mask size is rounded to the next multiple of
+.IR "sizeof(unsigned long)" ,
+but the kernel will use bits only up to
+.IR maxnode .
+A NULL value of
+.I nodemask
+or a
+.I maxnode
+value of zero specifies the empty set of nodes.
+If the value of
+.I maxnode
+is zero,
+the
+.I nodemask
+argument is ignored.
+.P
+Where a
+.I nodemask
+is required, it must contain at least one node that is on-line,
+allowed by the process's current cpuset context,
+(unless the
+.B MPOL_F_STATIC_NODES
+mode flag is specified),
+and contains memory.
+If the
+.B MPOL_F_STATIC_NODES
+is set in
+.I mode
+and a required
+.I nodemask
+contains no nodes that are allowed by the process's current cpuset context,
+the memory policy reverts to
+.IR "local allocation" .
+This effectively overrides the specified policy until the process's
+cpuset context includes one or more of the nodes specified by
+.IR nodemask .
+.P
+The
+.I mode
+argument must include one of the following values:
+.TP
+.B MPOL_DEFAULT
+This mode specifies that any nondefault thread memory policy be removed,
+so that the memory policy "falls back" to the system default policy.
+The system default policy is "local allocation"\[em]that is,
+allocate memory on the node of the CPU that triggered the allocation.
+.I nodemask
+must be specified as NULL.
+If the "local node" contains no free memory, the system will
+attempt to allocate memory from a "near by" node.
+.TP
+.B MPOL_BIND
+This mode defines a strict policy that restricts memory allocation to the
+nodes specified in
+.IR nodemask .
+If
+.I nodemask
+specifies more than one node, page allocations will come from
+the node with the lowest numeric node ID first, until that node
+contains no free memory.
+Allocations will then come from the node with the next highest
+node ID specified in
+.I nodemask
+and so forth, until none of the specified nodes contain free memory.
+Pages will not be allocated from any node not specified in the
+.IR nodemask .
+.TP
+.B MPOL_INTERLEAVE
+This mode interleaves page allocations across the nodes specified in
+.I nodemask
+in numeric node ID order.
+This optimizes for bandwidth instead of latency
+by spreading out pages and memory accesses to those pages across
+multiple nodes.
+However, accesses to a single page will still be limited to
+the memory bandwidth of a single node.
+.\" NOTE:  the following sentence doesn't make sense in the context
+.\" of set_mempolicy() -- no memory area specified.
+.\" To be effective the memory area should be fairly large,
+.\" at least 1 MB or bigger.
+.TP
+.BR MPOL_WEIGHTED_INTERLEAVE " (since Linux 6.9)"
+.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
+This mode interleaves page allocations across the nodes specified in
+.I nodemask
+according to the weights in
+.IR /sys/kernel/mm/mempolicy/weighted_interleave .
+For example, if bits 0, 2, and 5 are set in
+.IR nodemask ,
+and the contents of
+.IR /sys/kernel/mm/mempolicy/weighted_interleave/node0 ,
+.IR /sys/ .\|.\|. /node2 ,
+and
+.IR /sys/ .\|.\|. /node5
+are 4, 7, and 9, respectively,
+then pages in this region will be allocated on nodes 0, 2, and 5
+in a 4:7:9 ratio.
+.TP
+.B MPOL_PREFERRED
+This mode sets the preferred node for allocation.
+The kernel will try to allocate pages from this node first
+and fall back to "near by" nodes if the preferred node is low on free
+memory.
+If
+.I nodemask
+specifies more than one node ID, the first node in the
+mask will be selected as the preferred node.
+If the
+.I nodemask
+and
+.I maxnode
+arguments specify the empty set, then the policy
+specifies "local allocation"
+(like the system default policy discussed above).
+.TP
+.BR MPOL_LOCAL " (since Linux 3.8)"
+.\" commit 479e2802d09f1e18a97262c4c6f8f17ae5884bd8
+.\" commit f2a07f40dbc603c15f8b06e6ec7f768af67b424f
+This mode specifies "local allocation"; the memory is allocated on
+the node of the CPU that triggered the allocation (the "local node").
+The
+.I nodemask
+and
+.I maxnode
+arguments must specify the empty set.
+If the "local node" is low on free memory,
+the kernel will try to allocate memory from other nodes.
+The kernel will allocate memory from the "local node"
+whenever memory for this node is available.
+If the "local node" is not allowed by the process's current cpuset context,
+the kernel will try to allocate memory from other nodes.
+The kernel will allocate memory from the "local node" whenever
+it becomes allowed by the process's current cpuset context.
+.P
+The thread memory policy is preserved across an
+.BR execve (2),
+and is inherited by child threads created using
+.BR fork (2)
+or
+.BR clone (2).
+.SH RETURN VALUE
+On success,
+.BR set_mempolicy ()
+returns 0;
+on error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Part of all of the memory range specified by
+.I nodemask
+and
+.I maxnode
+points outside your accessible address space.
+.TP
+.B EINVAL
+.I mode
+is invalid.
+Or,
+.I mode
+is
+.B MPOL_DEFAULT
+and
+.I nodemask
+is nonempty,
+or
+.I mode
+is
+.B MPOL_BIND
+or
+.B MPOL_INTERLEAVE
+and
+.I nodemask
+is empty.
+Or,
+.I maxnode
+specifies more than a page worth of bits.
+Or,
+.I nodemask
+specifies one or more node IDs that are
+greater than the maximum supported node ID.
+Or, none of the node IDs specified by
+.I nodemask
+are on-line and allowed by the process's current cpuset context,
+or none of the specified nodes contain memory.
+Or, the
+.I mode
+argument specified both
+.B MPOL_F_STATIC_NODES
+and
+.BR MPOL_F_RELATIVE_NODES .
+Or, the
+.B MPOL_F_NUMA_BALANCING
+isn't supported by the kernel, or is used with
+.I mode
+other than
+.BR MPOL_BIND .
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.7.
+.SH NOTES
+Memory policy is not remembered if the page is swapped out.
+When such a page is paged back in, it will use the policy of
+the thread or memory range that is in effect at the time the
+page is allocated.
+.P
+For information on library support, see
+.BR numa (7).
+.SH SEE ALSO
+.BR get_mempolicy (2),
+.BR getcpu (2),
+.BR mbind (2),
+.BR mmap (2),
+.BR numa (3),
+.BR cpuset (7),
+.BR numa (7),
+.BR numactl (8)
diff --git a/man/man2/set_robust_list.2 b/man/man2/set_robust_list.2
new file mode 100644
index 000000000..a38aa23ed
--- /dev/null
+++ b/man/man2/set_robust_list.2
@@ -0,0 +1 @@
+.so man2/get_robust_list.2
diff --git a/man/man2/set_thread_area.2 b/man/man2/set_thread_area.2
new file mode 100644
index 000000000..feef67c4c
--- /dev/null
+++ b/man/man2/set_thread_area.2
@@ -0,0 +1,229 @@
+.\" Copyright (C) 2003 Free Software Foundation, Inc.
+.\" Copyright (C) 2015 Andrew Lutomirski
+.\" Author: Kent Yoder
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH set_thread_area 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+get_thread_area, set_thread_area \- manipulate thread-local storage information
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.B #if defined __i386__ || defined __x86_64__
+.BR "# include <asm/ldt.h>" "        /* Definition of " "struct user_desc" " */"
+.P
+.BI "int syscall(SYS_get_thread_area, struct user_desc *" u_info );
+.BI "int syscall(SYS_set_thread_area, struct user_desc *" u_info );
+.P
+.B #elif defined __m68k__
+.P
+.B "int syscall(SYS_get_thread_area);"
+.BI "int syscall(SYS_set_thread_area, unsigned long " tp );
+.P
+.B #elif defined __mips__ || defined __csky__
+.P
+.BI "int syscall(SYS_set_thread_area, unsigned long " addr );
+.P
+.B #endif
+.fi
+.P
+.IR Note :
+glibc provides no wrappers for these system calls,
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+These calls provide architecture-specific support for a thread-local storage
+implementation.
+At the moment,
+.BR set_thread_area ()
+is available on m68k, MIPS, C-SKY, and x86 (both 32-bit and 64-bit variants);
+.BR get_thread_area ()
+is available on m68k and x86.
+.P
+On m68k, MIPS and C-SKY,
+.BR set_thread_area ()
+allows storing an arbitrary pointer (provided in the
+.B tp
+argument on m68k and in the
+.B addr
+argument on MIPS and C-SKY)
+in the kernel data structure associated with the calling thread;
+this pointer can later be retrieved using
+.BR get_thread_area ()
+(see also NOTES
+for information regarding obtaining the thread pointer on MIPS).
+.P
+On x86, Linux dedicates three global descriptor table (GDT) entries for
+thread-local storage.
+For more information about the GDT, see the
+Intel Software Developer's Manual or the AMD Architecture Programming Manual.
+.P
+Both of these system calls take an argument that is a pointer
+to a structure of the following type:
+.P
+.in +4n
+.EX
+struct user_desc {
+    unsigned int  entry_number;
+    unsigned int  base_addr;
+    unsigned int  limit;
+    unsigned int  seg_32bit:1;
+    unsigned int  contents:2;
+    unsigned int  read_exec_only:1;
+    unsigned int  limit_in_pages:1;
+    unsigned int  seg_not_present:1;
+    unsigned int  useable:1;
+#ifdef __x86_64__
+    unsigned int  lm:1;
+#endif
+};
+.EE
+.in
+.P
+.BR get_thread_area ()
+reads the GDT entry indicated by
+.I u_info\->entry_number
+and fills in the rest of the fields in
+.IR u_info .
+.P
+.BR set_thread_area ()
+sets a TLS entry in the GDT.
+.P
+The TLS array entry set by
+.BR set_thread_area ()
+corresponds to the value of
+.I u_info\->entry_number
+passed in by the user.
+If this value is in bounds,
+.BR set_thread_area ()
+writes the TLS descriptor pointed to by
+.I u_info
+into the thread's TLS array.
+.P
+When
+.BR set_thread_area ()
+is passed an
+.I entry_number
+of \-1, it searches for a free TLS entry.
+If
+.BR set_thread_area ()
+finds a free TLS entry, the value of
+.I u_info\->entry_number
+is set upon return to show which entry was changed.
+.P
+A
+.I user_desc
+is considered "empty" if
+.I read_exec_only
+and
+.I seg_not_present
+are set to 1 and all of the other fields are 0.
+If an "empty" descriptor is passed to
+.BR set_thread_area (),
+the corresponding TLS entry will be cleared.
+See BUGS for additional details.
+.P
+Since Linux 3.19,
+.BR set_thread_area ()
+cannot be used to write non-present segments, 16-bit segments, or code
+segments, although clearing a segment is still acceptable.
+.SH RETURN VALUE
+On x86, these system calls
+return 0 on success, and \-1 on failure, with
+.I errno
+set to indicate the error.
+.P
+On C-SKY, MIPS and m68k,
+.BR set_thread_area ()
+always returns 0.
+On m68k,
+.BR get_thread_area ()
+returns the thread area pointer value
+(previously set via
+.BR set_thread_area ()).
+.SH ERRORS
+.TP
+.B EFAULT
+\fIu_info\fP is an invalid pointer.
+.TP
+.B EINVAL
+\fIu_info\->entry_number\fP is out of bounds.
+.TP
+.B ENOSYS
+.BR get_thread_area ()
+or
+.BR set_thread_area ()
+was invoked as a 64-bit system call.
+.TP
+.B ESRCH
+.RB ( set_thread_area ())
+A free TLS entry could not be located.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR set_thread_area ()
+Linux 2.5.29.
+.TP
+.BR get_thread_area ()
+Linux 2.5.32.
+.SH NOTES
+These system calls are generally intended for use only by threading libraries.
+.P
+.BR arch_prctl (2)
+can interfere with
+.BR set_thread_area ()
+on x86.
+See
+.BR arch_prctl (2)
+for more details.
+This is not normally a problem, as
+.BR arch_prctl (2)
+is normally used only by 64-bit programs.
+.P
+On MIPS, the current value of the thread area pointer can be obtained
+using the instruction:
+.P
+.in +4n
+.EX
+rdhwr dest, $29
+.EE
+.in
+.P
+This instruction traps and is handled by kernel.
+.SH BUGS
+On 64-bit kernels before Linux 3.19,
+.\" commit e30ab185c490e9a9381385529e0fd32f0a399495
+one of the padding bits in
+.IR user_desc ,
+if set, would prevent the descriptor from being considered empty (see
+.BR modify_ldt (2)).
+As a result, the only reliable way to clear a TLS entry is to use
+.BR memset (3)
+to zero the entire
+.I user_desc
+structure, including padding bits, and then to set the
+.I read_exec_only
+and
+.I seg_not_present
+bits.
+On Linux 3.19, a
+.I user_desc
+consisting entirely of zeros except for
+.I entry_number
+will also be interpreted as a request to clear a TLS entry, but this
+behaved differently on older kernels.
+.P
+Prior to Linux 3.19, the DS and ES segment registers must not reference
+TLS entries.
+.SH SEE ALSO
+.BR arch_prctl (2),
+.BR modify_ldt (2),
+.BR ptrace (2)
+.RB ( PTRACE_GET_THREAD_AREA " and " PTRACE_SET_THREAD_AREA )
diff --git a/man/man2/set_tid_address.2 b/man/man2/set_tid_address.2
new file mode 100644
index 000000000..c60144913
--- /dev/null
+++ b/man/man2/set_tid_address.2
@@ -0,0 +1,97 @@
+.\" Copyright (C) 2004 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH set_tid_address 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+set_tid_address \- set pointer to thread ID
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "pid_t syscall(SYS_set_tid_address, int *" tidptr );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR set_tid_address (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+For each thread, the kernel maintains two attributes (addresses) called
+.I set_child_tid
+and
+.IR clear_child_tid .
+These two attributes contain the value NULL by default.
+.TP
+.I set_child_tid
+If a thread is started using
+.BR clone (2)
+with the
+.B CLONE_CHILD_SETTID
+flag,
+.I set_child_tid
+is set to the value passed in the
+.I ctid
+argument of that system call.
+.IP
+When
+.I set_child_tid
+is set, the very first thing the new thread does
+is to write its thread ID at this address.
+.TP
+.I clear_child_tid
+If a thread is started using
+.BR clone (2)
+with the
+.B CLONE_CHILD_CLEARTID
+flag,
+.I clear_child_tid
+is set to the value passed in the
+.I ctid
+argument of that system call.
+.P
+The system call
+.BR set_tid_address ()
+sets the
+.I clear_child_tid
+value for the calling thread to
+.IR tidptr .
+.P
+When a thread whose
+.I clear_child_tid
+is not NULL terminates, then,
+if the thread is sharing memory with other threads,
+then 0 is written at the address specified in
+.I clear_child_tid
+and the kernel performs the following operation:
+.P
+.in +4n
+.EX
+futex(clear_child_tid, FUTEX_WAKE, 1, NULL, NULL, 0);
+.EE
+.in
+.P
+The effect of this operation is to wake a single thread that
+is performing a futex wait on the memory location.
+Errors from the futex wake operation are ignored.
+.SH RETURN VALUE
+.BR set_tid_address ()
+always returns the caller's thread ID.
+.SH ERRORS
+.BR set_tid_address ()
+always succeeds.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.48.
+.P
+Details as given here are valid since Linux 2.5.49.
+.SH SEE ALSO
+.BR clone (2),
+.BR futex (2),
+.BR gettid (2)
diff --git a/man/man2/setdomainname.2 b/man/man2/setdomainname.2
new file mode 100644
index 000000000..1c1594cbe
--- /dev/null
+++ b/man/man2/setdomainname.2
@@ -0,0 +1 @@
+.so man2/getdomainname.2
diff --git a/man/man2/setegid.2 b/man/man2/setegid.2
new file mode 100644
index 000000000..85032b503
--- /dev/null
+++ b/man/man2/setegid.2
@@ -0,0 +1 @@
+.so man2/seteuid.2
diff --git a/man/man2/seteuid.2 b/man/man2/seteuid.2
new file mode 100644
index 000000000..0eae04f79
--- /dev/null
+++ b/man/man2/seteuid.2
@@ -0,0 +1,134 @@
+.\" Copyright (C) 2001 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" [should really be seteuid.3]
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.TH seteuid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+seteuid, setegid \- set effective user or group ID
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int seteuid(uid_t " euid );
+.BI "int setegid(gid_t " egid );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR seteuid (),
+.BR setegid ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR seteuid ()
+sets the effective user ID of the calling process.
+Unprivileged processes may only set the effective user ID to the
+real user ID, the effective user ID or the saved set-user-ID.
+.P
+Precisely the same holds for
+.BR setegid ()
+with "group" instead of "user".
+.\" When
+.\" .I euid
+.\" equals \-1, nothing is changed.
+.\" (This is an artifact of the implementation in glibc of seteuid()
+.\" using setresuid(2).)
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+.IR Note :
+there are cases where
+.BR seteuid ()
+can fail even when the caller is UID 0;
+it is a grave security error to omit checking for a failure return from
+.BR seteuid ().
+.SH ERRORS
+.TP
+.B EINVAL
+The target user or group ID is not valid in this user namespace.
+.TP
+.B EPERM
+In the case of
+.BR seteuid ():
+the calling process is not privileged (does not have the
+.B CAP_SETUID
+capability in its user namespace) and
+.I euid
+does not match the current real user ID, current effective user ID,
+or current saved set-user-ID.
+.IP
+In the case of
+.BR setegid ():
+the calling process is not privileged (does not have the
+.B CAP_SETGID
+capability in its user namespace) and
+.I egid
+does not match the current real group ID, current effective group ID,
+or current saved set-group-ID.
+.SH VERSIONS
+Setting the effective user (group) ID to the
+saved set-user-ID (saved set-group-ID) is
+possible since Linux 1.1.37 (1.1.38).
+On an arbitrary system one should check
+.BR _POSIX_SAVED_IDS .
+.P
+Under glibc 2.0,
+.BI seteuid( euid )
+is equivalent to
+.BI setreuid(\-1, " euid" )
+and hence may change the saved set-user-ID.
+Under glibc 2.1 and later, it is equivalent to
+.BI setresuid(\-1, " euid" ", \-1)"
+and hence does not change the saved set-user-ID.
+Analogous remarks hold for
+.BR setegid (),
+with the difference that the change in implementation from
+.BI setregid(\-1, " egid" )
+to
+.BI setresgid(\-1, " egid" ", \-1)"
+occurred in glibc 2.2 or 2.3 (depending on the hardware architecture).
+.P
+According to POSIX.1,
+.BR seteuid ()
+.RB ( setegid ())
+need not permit
+.I euid
+.RI ( egid )
+to be the same value as the current effective user (group) ID,
+and some implementations do not permit this.
+.SS C library/kernel differences
+On Linux,
+.BR seteuid ()
+and
+.BR setegid ()
+are implemented as library functions that call, respectively,
+.BR setresuid (2)
+and
+.BR setresgid (2).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.SH SEE ALSO
+.BR geteuid (2),
+.BR setresuid (2),
+.BR setreuid (2),
+.BR setuid (2),
+.BR capabilities (7),
+.BR credentials (7),
+.BR user_namespaces (7)
diff --git a/man/man2/setfsgid.2 b/man/man2/setfsgid.2
new file mode 100644
index 000000000..3d02a65a8
--- /dev/null
+++ b/man/man2/setfsgid.2
@@ -0,0 +1,109 @@
+.\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\" and Copyright (C) 2019, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created   1995-08-06 Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\" Modified  2000-07-01 aeb
+.\" Modified  2002-07-23 aeb
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.TH setfsgid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setfsgid \- set group identity used for filesystem checks
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/fsuid.h>
+.P
+.BI "[[deprecated]] int setfsgid(gid_t " fsgid );
+.fi
+.SH DESCRIPTION
+On Linux, a process has both a filesystem group ID and an effective group ID.
+The (Linux-specific) filesystem group ID is used
+for permissions checking when accessing filesystem objects,
+while the effective group ID is used for some other kinds
+of permissions checks (see
+.BR credentials (7)).
+.P
+Normally, the value of the process's filesystem group ID
+is the same as the value of its effective group ID.
+This is so, because whenever a process's effective group ID is changed,
+the kernel also changes the filesystem group ID to be the same as
+the new value of the effective group ID.
+A process can cause the value of its filesystem group ID to diverge
+from its effective group ID by using
+.BR setfsgid ()
+to change its filesystem group ID to the value given in
+.IR fsgid .
+.P
+.BR setfsgid ()
+will succeed only if the caller is the superuser or if
+.I fsgid
+matches either the caller's real group ID, effective group ID,
+saved set-group-ID, or current the filesystem user ID.
+.SH RETURN VALUE
+On both success and failure,
+this call returns the previous filesystem group ID of the caller.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 1.2.
+.\" Linux 1.1.44
+.\" and in libc since libc 4.7.6.
+.SS C library/kernel differences
+In glibc 2.15 and earlier,
+when the wrapper for this system call determines that the argument can't be
+passed to the kernel without integer truncation (because the kernel
+is old and does not support 32-bit group IDs),
+it will return \-1 and set \fIerrno\fP to
+.B EINVAL
+without attempting
+the system call.
+.SH NOTES
+The filesystem group ID concept and the
+.BR setfsgid ()
+system call were invented for historical reasons that are
+no longer applicable on modern Linux kernels.
+See
+.BR setfsuid (2)
+for a discussion of why the use of both
+.BR setfsuid (2)
+and
+.BR setfsgid ()
+is nowadays unneeded.
+.P
+The original Linux
+.BR setfsgid ()
+system call supported only 16-bit group IDs.
+Subsequently, Linux 2.4 added
+.BR setfsgid32 ()
+supporting 32-bit IDs.
+The glibc
+.BR setfsgid ()
+wrapper function transparently deals with the variation across kernel versions.
+.SH BUGS
+No error indications of any kind are returned to the caller,
+and the fact that both successful and unsuccessful calls return
+the same value makes it impossible to directly determine
+whether the call succeeded or failed.
+Instead, the caller must resort to looking at the return value
+from a further call such as
+.I setfsgid(\-1)
+(which will always fail), in order to determine if a preceding call to
+.BR setfsgid ()
+changed the filesystem group ID.
+At the very
+least,
+.B EPERM
+should be returned when the call fails (because the caller lacks the
+.B CAP_SETGID
+capability).
+.SH SEE ALSO
+.BR kill (2),
+.BR setfsuid (2),
+.BR capabilities (7),
+.BR credentials (7)
diff --git a/man/man2/setfsgid32.2 b/man/man2/setfsgid32.2
new file mode 100644
index 000000000..fdb8bdcce
--- /dev/null
+++ b/man/man2/setfsgid32.2
@@ -0,0 +1 @@
+.so man2/setfsgid.2
diff --git a/man/man2/setfsuid.2 b/man/man2/setfsuid.2
new file mode 100644
index 000000000..c6e75dafa
--- /dev/null
+++ b/man/man2/setfsuid.2
@@ -0,0 +1,127 @@
+.\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\" and Copyright (C) 2013, 2019, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created   1995-08-06 Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\" Modified  2000-07-01 aeb
+.\" Modified  2002-07-23 aeb
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.TH setfsuid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setfsuid \- set user identity used for filesystem checks
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/fsuid.h>
+.P
+.BI "[[deprecated]] int setfsuid(uid_t " fsuid );
+.fi
+.SH DESCRIPTION
+On Linux, a process has both a filesystem user ID and an effective user ID.
+The (Linux-specific) filesystem user ID is used
+for permissions checking when accessing filesystem objects,
+while the effective user ID is used for various other kinds
+of permissions checks (see
+.BR credentials (7)).
+.P
+Normally, the value of the process's filesystem user ID
+is the same as the value of its effective user ID.
+This is so, because whenever a process's effective user ID is changed,
+the kernel also changes the filesystem user ID to be the same as
+the new value of the effective user ID.
+A process can cause the value of its filesystem user ID to diverge
+from its effective user ID by using
+.BR setfsuid ()
+to change its filesystem user ID to the value given in
+.IR fsuid .
+.P
+Explicit calls to
+.BR setfsuid ()
+and
+.BR setfsgid (2)
+are (were) usually used only by programs such as the Linux NFS server that
+need to change what user and group ID is used for file access without a
+corresponding change in the real and effective user and group IDs.
+A change in the normal user IDs for a program such as the NFS server
+is (was) a security hole that can expose it to unwanted signals.
+(However, this issue is historical; see below.)
+.P
+.BR setfsuid ()
+will succeed only if the caller is the superuser or if
+.I fsuid
+matches either the caller's real user ID, effective user ID,
+saved set-user-ID, or current filesystem user ID.
+.SH RETURN VALUE
+On both success and failure,
+this call returns the previous filesystem user ID of the caller.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 1.2.
+.\" Linux 1.1.44
+.\" and in libc since libc 4.7.6.
+.P
+At the time when this system call was introduced, one process
+could send a signal to another process with the same effective user ID.
+This meant that if a privileged process changed its effective user ID
+for the purpose of file permission checking,
+then it could become vulnerable to receiving signals
+sent by another (unprivileged) process with the same user ID.
+The filesystem user ID attribute was thus added to allow a process to
+change its user ID for the purposes of file permission checking without
+at the same time becoming vulnerable to receiving unwanted signals.
+Since Linux 2.0, signal permission handling is different (see
+.BR kill (2)),
+with the result that a process can change its effective user ID
+without being vulnerable to receiving signals from unwanted processes.
+Thus,
+.BR setfsuid ()
+is nowadays unneeded and should be avoided in new applications
+(likewise for
+.BR setfsgid (2)).
+.P
+The original Linux
+.BR setfsuid ()
+system call supported only 16-bit user IDs.
+Subsequently, Linux 2.4 added
+.BR setfsuid32 ()
+supporting 32-bit IDs.
+The glibc
+.BR setfsuid ()
+wrapper function transparently deals with the variation across kernel versions.
+.SS C library/kernel differences
+In glibc 2.15 and earlier,
+when the wrapper for this system call determines that the argument can't be
+passed to the kernel without integer truncation (because the kernel
+is old and does not support 32-bit user IDs),
+it will return \-1 and set \fIerrno\fP to
+.B EINVAL
+without attempting
+the system call.
+.SH BUGS
+No error indications of any kind are returned to the caller,
+and the fact that both successful and unsuccessful calls return
+the same value makes it impossible to directly determine
+whether the call succeeded or failed.
+Instead, the caller must resort to looking at the return value
+from a further call such as
+.I setfsuid(\-1)
+(which will always fail), in order to determine if a preceding call to
+.BR setfsuid ()
+changed the filesystem user ID.
+At the very
+least,
+.B EPERM
+should be returned when the call fails (because the caller lacks the
+.B CAP_SETUID
+capability).
+.SH SEE ALSO
+.BR kill (2),
+.BR setfsgid (2),
+.BR capabilities (7),
+.BR credentials (7)
diff --git a/man/man2/setfsuid32.2 b/man/man2/setfsuid32.2
new file mode 100644
index 000000000..1ea58fd02
--- /dev/null
+++ b/man/man2/setfsuid32.2
@@ -0,0 +1 @@
+.so man2/setfsuid.2
diff --git a/man/man2/setgid.2 b/man/man2/setgid.2
new file mode 100644
index 000000000..4ca3f1765
--- /dev/null
+++ b/man/man2/setgid.2
@@ -0,0 +1,92 @@
+.\" Copyright (C), 1994, Graeme W. Wilford. (Wilf.)
+.\" and Copyright (C) 2010, 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Fri Jul 29th 12:56:44 BST 1994  Wilf. <G.Wilford@ee.surrey.ac.uk>
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2002-03-09 by aeb
+.\"
+.TH setgid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setgid \- set group identity
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int setgid(gid_t " gid );
+.fi
+.SH DESCRIPTION
+.BR setgid ()
+sets the effective group ID of the calling process.
+If the calling process is privileged (more precisely: has the
+.B CAP_SETGID
+capability in its user namespace),
+the real GID and saved set-group-ID are also set.
+.P
+Under Linux,
+.BR setgid ()
+is implemented like the POSIX version with the
+.B _POSIX_SAVED_IDS
+feature.
+This allows a set-group-ID program that is not set-user-ID-root
+to drop all of its group
+privileges, do some un-privileged work, and then reengage the original
+effective group ID in a secure manner.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The group ID specified in
+.I gid
+is not valid in this user namespace.
+.TP
+.B EPERM
+The calling process is not privileged (does not have the
+\fBCAP_SETGID\fP capability in its user namespace), and
+.I gid
+does not match the real group ID or saved set-group-ID of
+the calling process.
+.SH VERSIONS
+.SS C library/kernel differences
+At the kernel level, user IDs and group IDs are a per-thread attribute.
+However, POSIX requires that all threads in a process
+share the same credentials.
+The NPTL threading implementation handles the POSIX requirements by
+providing wrapper functions for
+the various system calls that change process UIDs and GIDs.
+These wrapper functions (including the one for
+.BR setgid ())
+employ a signal-based technique to ensure
+that when one thread changes credentials,
+all of the other threads in the process also change their credentials.
+For details, see
+.BR nptl (7).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.P
+The original Linux
+.BR setgid ()
+system call supported only 16-bit group IDs.
+Subsequently, Linux 2.4 added
+.BR setgid32 ()
+supporting 32-bit IDs.
+The glibc
+.BR setgid ()
+wrapper function transparently deals with the variation across kernel versions.
+.SH SEE ALSO
+.BR getgid (2),
+.BR setegid (2),
+.BR setregid (2),
+.BR capabilities (7),
+.BR credentials (7),
+.BR user_namespaces (7)
diff --git a/man/man2/setgid32.2 b/man/man2/setgid32.2
new file mode 100644
index 000000000..bc8ef19ca
--- /dev/null
+++ b/man/man2/setgid32.2
@@ -0,0 +1 @@
+.so man2/setgid.2
diff --git a/man/man2/setgroups.2 b/man/man2/setgroups.2
new file mode 100644
index 000000000..0ae4cc0b1
--- /dev/null
+++ b/man/man2/setgroups.2
@@ -0,0 +1 @@
+.so man2/getgroups.2
diff --git a/man/man2/setgroups32.2 b/man/man2/setgroups32.2
new file mode 100644
index 000000000..478fb63ef
--- /dev/null
+++ b/man/man2/setgroups32.2
@@ -0,0 +1 @@
+.so man2/setgroups.2
diff --git a/man/man2/sethostname.2 b/man/man2/sethostname.2
new file mode 100644
index 000000000..e1fa2a617
--- /dev/null
+++ b/man/man2/sethostname.2
@@ -0,0 +1 @@
+.so man2/gethostname.2
diff --git a/man/man2/setitimer.2 b/man/man2/setitimer.2
new file mode 100644
index 000000000..9518567e0
--- /dev/null
+++ b/man/man2/setitimer.2
@@ -0,0 +1 @@
+.so man2/getitimer.2
diff --git a/man/man2/setns.2 b/man/man2/setns.2
new file mode 100644
index 000000000..860ee7e10
--- /dev/null
+++ b/man/man2/setns.2
@@ -0,0 +1,419 @@
+.\" Copyright (C) 2011, Eric Biederman <ebiederm@xmission.com>
+.\" and Copyright (C) 2011, 2012, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.\"
+.TH setns 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setns \- reassociate thread with a namespace
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sched.h>
+.P
+.BI "int setns(int " fd ", int " nstype );
+.fi
+.SH DESCRIPTION
+The
+.BR setns ()
+system call allows the calling thread to move into different namespaces.
+The
+.I fd
+argument is one of the following:
+.IP \[bu] 3
+a file descriptor referring to one of the magic links in a
+.IR /proc/ pid /ns/
+directory (or a bind mount to such a link);
+.IP \[bu]
+a PID file descriptor (see
+.BR pidfd_open (2)).
+.P
+The
+.I nstype
+argument is interpreted differently in each case.
+.\"
+.SS fd refers to a \fI/proc/\fPpid\fI/ns/\fP link
+If
+.I fd
+refers to a
+.IR /proc/ pid /ns/
+link, then
+.BR setns ()
+reassociates the calling thread with the namespace associated with that link,
+subject to any constraints imposed by the
+.I nstype
+argument.
+In this usage, each call to
+.BR setns ()
+changes just one of the caller's namespace memberships.
+.P
+The
+.I nstype
+argument specifies which type of namespace
+the calling thread may be reassociated with.
+This argument can have
+.I one
+of the following values:
+.TP
+.B 0
+Allow any type of namespace to be joined.
+.TP
+.BR CLONE_NEWCGROUP " (since Linux 4.6)"
+.I fd
+must refer to a cgroup namespace.
+.TP
+.BR CLONE_NEWIPC " (since Linux 3.0)"
+.I fd
+must refer to an IPC namespace.
+.TP
+.BR CLONE_NEWNET " (since Linux 3.0)"
+.I fd
+must refer to a network namespace.
+.TP
+.BR CLONE_NEWNS " (since Linux 3.8)"
+.I fd
+must refer to a mount namespace.
+.TP
+.BR CLONE_NEWPID " (since Linux 3.8)"
+.I fd
+must refer to a descendant PID namespace.
+.TP
+.BR CLONE_NEWTIME " (since Linux 5.8)"
+.\" commit 76c12881a38aaa83e1eb4ce2fada36c3a732bad4
+.I fd
+must refer to a time namespace.
+.TP
+.BR CLONE_NEWUSER " (since Linux 3.8)"
+.I fd
+must refer to a user namespace.
+.TP
+.BR CLONE_NEWUTS " (since Linux 3.0)"
+.I fd
+must refer to a UTS namespace.
+.P
+Specifying
+.I nstype
+as 0 suffices if the caller knows (or does not care)
+what type of namespace is referred to by
+.IR fd .
+Specifying a nonzero value for
+.I nstype
+is useful if the caller does not know what type of namespace is referred to by
+.I fd
+and wants to ensure that the namespace is of a particular type.
+(The caller might not know the type of the namespace referred to by
+.I fd
+if the file descriptor was opened by another process and, for example,
+passed to the caller via a UNIX domain socket.)
+.\"
+.SS fd is a PID file descriptor
+Since Linux 5.8,
+.I fd
+may refer to a PID file descriptor obtained from
+.BR pidfd_open (2)
+or
+.BR clone (2).
+In this usage,
+.BR setns ()
+atomically moves the calling thread into one or more of the same namespaces
+as the thread referred to by
+.IR fd .
+.P
+The
+.I nstype
+argument is a bit mask specified by ORing together
+.I "one or more"
+of the
+.B CLONE_NEW*
+namespace constants listed above.
+The caller is moved into each of the target thread's namespaces
+that is specified in
+.IR nstype ;
+the caller's memberships in the remaining namespaces are left unchanged.
+.P
+For example, the following code would move the caller into the
+same user, network, and UTS namespaces as PID 1234,
+but would leave the caller's other namespace memberships unchanged:
+.P
+.in +4n
+.EX
+int fd = pidfd_open(1234, 0);
+setns(fd, CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWUTS);
+.EE
+.in
+.\"
+.SS Details for specific namespace types
+Note the following details and restrictions when reassociating with
+specific namespace types:
+.TP
+User namespaces
+A process reassociating itself with a user namespace must have the
+.B CAP_SYS_ADMIN
+.\" See kernel/user_namespace.c:userns_install() [3.8 source]
+capability in the target user namespace.
+(This necessarily implies that it is only possible to join
+a descendant user namespace.)
+Upon successfully joining a user namespace,
+a process is granted all capabilities in that namespace,
+regardless of its user and group IDs.
+.IP
+A multithreaded process may not change user namespace with
+.BR setns ().
+.IP
+It is not permitted to use
+.BR setns ()
+to reenter the caller's current user namespace.
+This prevents a caller that has dropped capabilities from regaining
+those capabilities via a call to
+.BR setns ().
+.IP
+For security reasons,
+.\" commit e66eded8309ebf679d3d3c1f5820d1f2ca332c71
+.\" https://lwn.net/Articles/543273/
+a process can't join a new user namespace if it is sharing
+filesystem-related attributes
+(the attributes whose sharing is controlled by the
+.BR clone (2)
+.B CLONE_FS
+flag) with another process.
+.IP
+For further details on user namespaces, see
+.BR user_namespaces (7).
+.TP
+Mount namespaces
+Changing the mount namespace requires that the caller possess both
+.B CAP_SYS_CHROOT
+and
+.B CAP_SYS_ADMIN
+capabilities in its own user namespace and
+.B CAP_SYS_ADMIN
+in the user namespace that owns the target mount namespace.
+.IP
+A process can't join a new mount namespace if it is sharing
+filesystem-related attributes
+(the attributes whose sharing is controlled by the
+.BR clone (2)
+.B CLONE_FS
+flag) with another process.
+.\" Above check is in fs/namespace.c:mntns_install() [3.8 source]
+.IP
+See
+.BR user_namespaces (7)
+for details on the interaction of user namespaces and mount namespaces.
+.TP
+PID namespaces
+In order to reassociate itself with a new PID namespace,
+the caller must have the
+.B CAP_SYS_ADMIN
+capability both in its own user namespace and in the user namespace
+that owns the target PID namespace.
+.IP
+Reassociating the PID namespace has somewhat different
+from other namespace types.
+Reassociating the calling thread with a PID namespace changes only
+the PID namespace that subsequently created child processes of
+the caller will be placed in;
+it does not change the PID namespace of the caller itself.
+.IP
+Reassociating with a PID namespace is allowed only if the target
+PID namespace is a descendant (child, grandchild, etc.)
+of, or is the same as, the current PID namespace of the caller.
+.IP
+For further details on PID namespaces, see
+.BR pid_namespaces (7).
+.TP
+Cgroup namespaces
+In order to reassociate itself with a new cgroup namespace,
+the caller must have the
+.B CAP_SYS_ADMIN
+capability both in its own user namespace and in the user namespace
+that owns the target cgroup namespace.
+.IP
+Using
+.BR setns ()
+to change the caller's cgroup namespace does not change
+the caller's cgroup memberships.
+.TP
+Network, IPC, time, and UTS namespaces
+In order to reassociate itself with a new network, IPC, time, or UTS namespace,
+the caller must have the
+.B CAP_SYS_ADMIN
+capability both in its own user namespace and in the user namespace
+that owns the target namespace.
+.SH RETURN VALUE
+On success,
+.BR setns ()
+returns 0.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+.I fd
+refers to a namespace whose type does not match that specified in
+.IR nstype .
+.TP
+.B EINVAL
+There is problem with reassociating
+the thread with the specified namespace.
+.TP
+.\" See kernel/pid_namespace.c::pidns_install() [kernel 3.18 sources]
+.B EINVAL
+The caller tried to join an ancestor (parent, grandparent, and so on)
+PID namespace.
+.TP
+.B EINVAL
+The caller attempted to join the user namespace
+in which it is already a member.
+.TP
+.B EINVAL
+.\" commit e66eded8309ebf679d3d3c1f5820d1f2ca332c71
+The caller shares filesystem
+.RB ( CLONE_FS )
+state (in particular, the root directory)
+with other processes and tried to join a new user namespace.
+.TP
+.B EINVAL
+.\" See kernel/user_namespace.c::userns_install() [kernel 3.15 sources]
+The caller is multithreaded and tried to join a new user namespace.
+.TP
+.B EINVAL
+.I fd
+is a PID file descriptor and
+.I nstype
+is invalid (e.g., it is 0).
+.TP
+.B ENOMEM
+Cannot allocate sufficient memory to change the specified namespace.
+.TP
+.B EPERM
+The calling thread did not have the required capability
+for this operation.
+.TP
+.B ESRCH
+.I fd
+is a PID file descriptor but the process it refers to no longer exists
+(i.e., it has terminated and been waited on).
+.SH STANDARDS
+Linux.
+.SH VERSIONS
+Linux 3.0,
+glibc 2.14.
+.SH NOTES
+For further information on the
+.IR /proc/ pid /ns/
+magic links, see
+.BR namespaces (7).
+.P
+Not all of the attributes that can be shared when
+a new thread is created using
+.BR clone (2)
+can be changed using
+.BR setns ().
+.SH EXAMPLES
+The program below takes two or more arguments.
+The first argument specifies the pathname of a namespace file in an existing
+.IR /proc/ pid /ns/
+directory.
+The remaining arguments specify a command and its arguments.
+The program opens the namespace file, joins that namespace using
+.BR setns (),
+and executes the specified command inside that namespace.
+.P
+The following shell session demonstrates the use of this program
+(compiled as a binary named
+.IR ns_exec )
+in conjunction with the
+.B CLONE_NEWUTS
+example program in the
+.BR clone (2)
+man page (complied as a binary named
+.IR newuts ).
+.P
+We begin by executing the example program in
+.BR clone (2)
+in the background.
+That program creates a child in a separate UTS namespace.
+The child changes the hostname in its namespace,
+and then both processes display the hostnames in their UTS namespaces,
+so that we can see that they are different.
+.P
+.in +4n
+.EX
+$ \fBsu\fP                   # Need privilege for namespace operations
+Password:
+# \fB./newuts bizarro &\fP
+[1] 3549
+clone() returned 3550
+uts.nodename in child:  bizarro
+uts.nodename in parent: antero
+# \fBuname \-n\fP             # Verify hostname in the shell
+antero
+.EE
+.in
+.P
+We then run the program shown below,
+using it to execute a shell.
+Inside that shell, we verify that the hostname is the one
+set by the child created by the first program:
+.P
+.in +4n
+.EX
+# \fB./ns_exec /proc/3550/ns/uts /bin/bash\fP
+# \fBuname \-n\fP             # Executed in shell started by ns_exec
+bizarro
+.EE
+.in
+.SS Program source
+.\" SRC BEGIN (setns.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int fd;
+\&
+    if (argc < 3) {
+        fprintf(stderr, "%s /proc/PID/ns/FILE cmd args...\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Get file descriptor for namespace; the file descriptor is opened
+       with O_CLOEXEC so as to ensure that it is not inherited by the
+       program that is later executed. */
+\&
+    fd = open(argv[1], O_RDONLY | O_CLOEXEC);
+    if (fd == \-1)
+        err(EXIT_FAILURE, "open");
+\&
+    if (setns(fd, 0) == \-1)       /* Join that namespace */
+        err(EXIT_FAILURE, "setns");
+\&
+    execvp(argv[2], &argv[2]);    /* Execute a command in namespace */
+    err(EXIT_FAILURE, "execvp");
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR nsenter (1),
+.BR clone (2),
+.BR fork (2),
+.BR unshare (2),
+.BR vfork (2),
+.BR namespaces (7),
+.BR unix (7)
diff --git a/man/man2/setpgid.2 b/man/man2/setpgid.2
new file mode 100644
index 000000000..d5f9bbd6b
--- /dev/null
+++ b/man/man2/setpgid.2
@@ -0,0 +1,329 @@
+.\" Copyright (c) 1983, 1991 Regents of the University of California.
+.\" and Copyright (C) 2007, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)getpgrp.2	6.4 (Berkeley) 3/10/91
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-04-15 by Michael Chastain <mec@shell.portal.com>:
+.\"   Added 'getpgid'.
+.\" Modified 1996-07-21 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 1996-11-06 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1999-09-02 by Michael Haardt <michael@moria.de>
+.\" Modified 2002-01-18 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2003-01-20 by Andries Brouwer <aeb@cwi.nl>
+.\" 2007-07-25, mtk, fairly substantial rewrites and rearrangements
+.\" of text.
+.\"
+.TH setpgid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setpgid, getpgid, setpgrp, getpgrp \- set/get process group
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int setpgid(pid_t " pid ", pid_t " pgid );
+.BI "pid_t getpgid(pid_t " pid );
+.P
+.BR "pid_t getpgrp(void);" "                            /* POSIX.1 version */"
+.BI "[[deprecated]] pid_t getpgrp(pid_t " pid ");\fR        /* BSD version */"
+.P
+.BR "int setpgrp(void);" "                              /* System V version */"
+.BI "[[deprecated]] int setpgrp(pid_t " pid ", pid_t " pgid ");\fR  /* BSD version */"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getpgid ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+.fi
+.P
+.BR setpgrp "() (POSIX.1):"
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE
+.fi
+.P
+.BR setpgrp "() (BSD),"
+.BR getpgrp "() (BSD):"
+.nf
+    [These are available only before glibc 2.19]
+    _BSD_SOURCE &&
+        ! (_POSIX_SOURCE || _POSIX_C_SOURCE || _XOPEN_SOURCE
+            || _GNU_SOURCE || _SVID_SOURCE)
+.fi
+.SH DESCRIPTION
+All of these interfaces are available on Linux,
+and are used for getting and setting the
+process group ID (PGID) of a process.
+The preferred, POSIX.1-specified ways of doing this are:
+.BR getpgrp (void),
+for retrieving the calling process's PGID; and
+.BR setpgid (),
+for setting a process's PGID.
+.P
+.BR setpgid ()
+sets the PGID of the process specified by
+.I pid
+to
+.IR pgid .
+If
+.I pid
+is zero, then the process ID of the calling process is used.
+If
+.I pgid
+is zero, then the PGID of the process specified by
+.I pid
+is made the same as its process ID.
+If
+.BR setpgid ()
+is used to move a process from one process
+group to another (as is done by some shells when creating pipelines),
+both process groups must be part of the same session (see
+.BR setsid (2)
+and
+.BR credentials (7)).
+In this case,
+the \fIpgid\fP specifies an existing process group to be joined and the
+session ID of that group must match the session ID of the joining process.
+.P
+The POSIX.1 version of
+.BR getpgrp (),
+which takes no arguments,
+returns the PGID of the calling process.
+.P
+.BR getpgid ()
+returns the PGID of the process specified by
+.IR pid .
+If
+.I pid
+is zero, the process ID of the calling process is used.
+(Retrieving the PGID of a process other than the caller is rarely
+necessary, and the POSIX.1
+.BR getpgrp ()
+is preferred for that task.)
+.P
+The System\ V-style
+.BR setpgrp (),
+which takes no arguments, is equivalent to
+.IR "setpgid(0,\ 0)" .
+.P
+The BSD-specific
+.BR setpgrp ()
+call, which takes arguments
+.I pid
+and
+.IR pgid ,
+is a wrapper function that calls
+.P
+.in +4n
+.EX
+setpgid(pid, pgid)
+.EE
+.in
+.P
+.\" The true BSD setpgrp() system call differs in allowing the PGID
+.\" to be set to arbitrary values, rather than being restricted to
+.\" PGIDs in the same session.
+Since glibc 2.19, the BSD-specific
+.BR setpgrp ()
+function is no longer exposed by
+.IR <unistd.h> ;
+calls should be replaced with the
+.BR setpgid ()
+call shown above.
+.P
+The BSD-specific
+.BR getpgrp ()
+call, which takes a single
+.I pid
+argument, is a wrapper function that calls
+.P
+.in +4n
+.EX
+getpgid(pid)
+.EE
+.in
+.P
+Since glibc 2.19, the BSD-specific
+.BR getpgrp ()
+function is no longer exposed by
+.IR <unistd.h> ;
+calls should be replaced with calls to the POSIX.1
+.BR getpgrp ()
+which takes no arguments (if the intent is to obtain the caller's PGID),
+or with the
+.BR getpgid ()
+call shown above.
+.SH RETURN VALUE
+On success,
+.BR setpgid ()
+and
+.BR setpgrp ()
+return zero.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+The POSIX.1
+.BR getpgrp ()
+always returns the PGID of the caller.
+.P
+.BR getpgid (),
+and the BSD-specific
+.BR getpgrp ()
+return a process group on success.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+An attempt was made to change the process group ID
+of one of the children of the calling process and the child had
+already performed an
+.BR execve (2)
+.RB ( setpgid (),
+.BR setpgrp ()).
+.TP
+.B EINVAL
+.I pgid
+is less than 0
+.RB ( setpgid (),
+.BR setpgrp ()).
+.TP
+.B EPERM
+An attempt was made to move a process into a process group in a
+different session, or to change the process
+group ID of one of the children of the calling process and the
+child was in a different session, or to change the process group ID of
+a session leader
+.RB ( setpgid (),
+.BR setpgrp ()).
+.TP
+.B EPERM
+The target process group does not exist.
+.RB ( setpgid (),
+.BR setpgrp ()).
+.TP
+.B ESRCH
+For
+.BR getpgid ():
+.I pid
+does not match any process.
+For
+.BR setpgid ():
+.I pid
+is not the calling process and not a child of the calling process.
+.SH STANDARDS
+.TP
+.BR getpgid ()
+.TQ
+.BR setpgid ()
+.TQ
+.BR getpgrp "() (no args)"
+.TQ
+.BR setpgrp "() (no args)"
+POSIX.1-2008 (but see HISTORY).
+.TP
+.BR setpgrp "() (2 args)"
+.TQ
+.BR getpgrp "() (1 arg)"
+None.
+.SH HISTORY
+.TP
+.BR getpgid ()
+.TQ
+.BR setpgid ()
+.TQ
+.BR getpgrp "() (no args)"
+POSIX.1-2001.
+.TP
+.BR setpgrp "() (no args)"
+POSIX.1-2001.
+POSIX.1-2008 marks it as obsolete.
+.TP
+.BR setpgrp "() (2 args)"
+.TQ
+.BR getpgrp "() (1 arg)"
+4.2BSD.
+.SH NOTES
+A child created via
+.BR fork (2)
+inherits its parent's process group ID.
+The PGID is preserved across an
+.BR execve (2).
+.P
+Each process group is a member of a session and each process is a
+member of the session of which its process group is a member.
+(See
+.BR credentials (7).)
+.P
+A session can have a controlling terminal.
+At any time, one (and only one) of the process groups
+in the session can be the foreground process group
+for the terminal;
+the remaining process groups are in the background.
+If a signal is generated from the terminal (e.g., typing the
+interrupt key to generate
+.BR SIGINT ),
+that signal is sent to the foreground process group.
+(See
+.BR termios (3)
+for a description of the characters that generate signals.)
+Only the foreground process group may
+.BR read (2)
+from the terminal;
+if a background process group tries to
+.BR read (2)
+from the terminal, then the group is sent a
+.B SIGTTIN
+signal, which suspends it.
+The
+.BR tcgetpgrp (3)
+and
+.BR tcsetpgrp (3)
+functions are used to get/set the foreground
+process group of the controlling terminal.
+.P
+The
+.BR setpgid ()
+and
+.BR getpgrp ()
+calls are used by programs such as
+.BR bash (1)
+to create process groups in order to implement shell job control.
+.P
+If the termination of a process causes a process group to become orphaned,
+and if any member of the newly orphaned process group is stopped, then a
+.B SIGHUP
+signal followed by a
+.B SIGCONT
+signal will be sent to each process
+in the newly orphaned process group.
+.\" exit.3 refers to the following text:
+An orphaned process group is one in which the parent of
+every member of process group is either itself also a member
+of the process group or is a member of a process group
+in a different session (see also
+.BR credentials (7)).
+.SH SEE ALSO
+.BR getuid (2),
+.BR setsid (2),
+.BR tcgetpgrp (3),
+.BR tcsetpgrp (3),
+.BR termios (3),
+.BR credentials (7)
diff --git a/man/man2/setpgrp.2 b/man/man2/setpgrp.2
new file mode 100644
index 000000000..d6b107a1c
--- /dev/null
+++ b/man/man2/setpgrp.2
@@ -0,0 +1 @@
+.so man2/setpgid.2
diff --git a/man/man2/setpriority.2 b/man/man2/setpriority.2
new file mode 100644
index 000000000..b1dcfd91d
--- /dev/null
+++ b/man/man2/setpriority.2
@@ -0,0 +1 @@
+.so man2/getpriority.2
diff --git a/man/man2/setregid.2 b/man/man2/setregid.2
new file mode 100644
index 000000000..ec3ff6416
--- /dev/null
+++ b/man/man2/setregid.2
@@ -0,0 +1 @@
+.so man2/setreuid.2
diff --git a/man/man2/setregid32.2 b/man/man2/setregid32.2
new file mode 100644
index 000000000..035df1724
--- /dev/null
+++ b/man/man2/setregid32.2
@@ -0,0 +1 @@
+.so man2/setregid.2
diff --git a/man/man2/setresgid.2 b/man/man2/setresgid.2
new file mode 100644
index 000000000..d6866a1de
--- /dev/null
+++ b/man/man2/setresgid.2
@@ -0,0 +1 @@
+.so man2/setresuid.2
diff --git a/man/man2/setresgid32.2 b/man/man2/setresgid32.2
new file mode 100644
index 000000000..dec1b9531
--- /dev/null
+++ b/man/man2/setresgid32.2
@@ -0,0 +1 @@
+.so man2/setresgid.2
diff --git a/man/man2/setresuid.2 b/man/man2/setresuid.2
new file mode 100644
index 000000000..5ee42b32d
--- /dev/null
+++ b/man/man2/setresuid.2
@@ -0,0 +1,147 @@
+.\" Copyright (C) 1997 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (C) 2005, 2010, 2014, 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified, 2003-05-26, Michael Kerrisk, <mtk.manpages@gmail.com>
+.TH setresuid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setresuid, setresgid \- set real, effective, and saved user or group ID
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BI "int setresuid(uid_t " ruid ", uid_t " euid ", uid_t " suid );
+.BI "int setresgid(gid_t " rgid ", gid_t " egid ", gid_t " sgid );
+.fi
+.SH DESCRIPTION
+.BR setresuid ()
+sets the real user ID, the effective user ID, and the
+saved set-user-ID of the calling process.
+.P
+An unprivileged process may change its real UID,
+effective UID, and saved set-user-ID, each to one of:
+the current real UID, the current effective UID, or the
+current saved set-user-ID.
+.P
+A privileged process (on Linux, one having the \fBCAP_SETUID\fP capability)
+may set its real UID, effective UID, and
+saved set-user-ID to arbitrary values.
+.P
+If one of the arguments equals \-1, the corresponding value is not changed.
+.P
+Regardless of what changes are made to the real UID, effective UID,
+and saved set-user-ID, the filesystem UID is always set to the same
+value as the (possibly new) effective UID.
+.P
+Completely analogously,
+.BR setresgid ()
+sets the real GID, effective GID, and saved set-group-ID
+of the calling process (and always modifies the filesystem GID
+to be the same as the effective GID),
+with the same restrictions for unprivileged processes.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+.IR Note :
+there are cases where
+.BR setresuid ()
+can fail even when the caller is UID 0;
+it is a grave security error to omit checking for a failure return from
+.BR setresuid ().
+.SH ERRORS
+.TP
+.B EAGAIN
+The call would change the caller's real UID (i.e.,
+.I ruid
+does not match the caller's real UID),
+but there was a temporary failure allocating the
+necessary kernel data structures.
+.TP
+.B EAGAIN
+.I ruid
+does not match the caller's real UID and this call would
+bring the number of processes belonging to the real user ID
+.I ruid
+over the caller's
+.B RLIMIT_NPROC
+resource limit.
+Since Linux 3.1, this error case no longer occurs
+(but robust applications should check for this error);
+see the description of
+.B EAGAIN
+in
+.BR execve (2).
+.TP
+.B EINVAL
+One or more of the target user or group IDs
+is not valid in this user namespace.
+.TP
+.B EPERM
+The calling process is not privileged (did not have the necessary
+capability in its user namespace)
+and tried to change the IDs to values that are not permitted.
+For
+.BR setresuid (),
+the necessary capability is
+.BR CAP_SETUID ;
+for
+.BR setresgid (),
+it is
+.BR CAP_SETGID .
+.SH VERSIONS
+.SS C library/kernel differences
+At the kernel level, user IDs and group IDs are a per-thread attribute.
+However, POSIX requires that all threads in a process
+share the same credentials.
+The NPTL threading implementation handles the POSIX requirements by
+providing wrapper functions for
+the various system calls that change process UIDs and GIDs.
+These wrapper functions (including those for
+.BR setresuid ()
+and
+.BR setresgid ())
+employ a signal-based technique to ensure
+that when one thread changes credentials,
+all of the other threads in the process also change their credentials.
+For details, see
+.BR nptl (7).
+.SH STANDARDS
+None.
+.SH HISTORY
+Linux 2.1.44,
+glibc 2.3.2.
+HP-UX, FreeBSD.
+.P
+The original Linux
+.BR setresuid ()
+and
+.BR setresgid ()
+system calls supported only 16-bit user and group IDs.
+Subsequently, Linux 2.4 added
+.BR setresuid32 ()
+and
+.BR setresgid32 (),
+supporting 32-bit IDs.
+The glibc
+.BR setresuid ()
+and
+.BR setresgid ()
+wrapper functions transparently deal with the variations across kernel versions.
+.SH SEE ALSO
+.BR getresuid (2),
+.BR getuid (2),
+.BR setfsgid (2),
+.BR setfsuid (2),
+.BR setreuid (2),
+.BR setuid (2),
+.BR capabilities (7),
+.BR credentials (7),
+.BR user_namespaces (7)
diff --git a/man/man2/setresuid32.2 b/man/man2/setresuid32.2
new file mode 100644
index 000000000..d6866a1de
--- /dev/null
+++ b/man/man2/setresuid32.2
@@ -0,0 +1 @@
+.so man2/setresuid.2
diff --git a/man/man2/setreuid.2 b/man/man2/setreuid.2
new file mode 100644
index 000000000..1ff0229a9
--- /dev/null
+++ b/man/man2/setreuid.2
@@ -0,0 +1,193 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" and Copyright (C) 2009, 2010, 2014, 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)setregid.2	6.4 (Berkeley) 3/10/91
+.\"
+.\" Modified Sat Jul 24 09:08:49 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Portions extracted from linux/kernel/sys.c:
+.\"             Copyright (C) 1991, 1992  Linus Torvalds
+.\"             May be distributed under the GNU General Public License
+.\" Changes: 1994-07-29 by Wilf <G.Wilford@ee.surrey.ac.uk>
+.\"          1994-08-02 by Wilf due to change in kernel.
+.\"          2004-07-04 by aeb
+.\"          2004-05-27 by Michael Kerrisk
+.\"
+.TH setreuid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setreuid, setregid \- set real and/or effective user or group ID
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int setreuid(uid_t " ruid ", uid_t " euid );
+.BI "int setregid(gid_t " rgid ", gid_t " egid );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR setreuid (),
+.BR setregid ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR setreuid ()
+sets real and effective user IDs of the calling process.
+.P
+Supplying a value of \-1 for either the real or effective user ID forces
+the system to leave that ID unchanged.
+.P
+Unprivileged processes may only set the effective user ID to the real user ID,
+the effective user ID, or the saved set-user-ID.
+.P
+Unprivileged users may only set the real user ID to
+the real user ID or the effective user ID.
+.P
+If the real user ID is set (i.e.,
+.I ruid
+is not \-1) or the effective user ID is set to a value
+not equal to the previous real user ID,
+the saved set-user-ID will be set to the new effective user ID.
+.P
+Completely analogously,
+.BR setregid ()
+sets real and effective group ID's of the calling process,
+and all of the above holds with "group" instead of "user".
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+.IR Note :
+there are cases where
+.BR setreuid ()
+can fail even when the caller is UID 0;
+it is a grave security error to omit checking for a failure return from
+.BR setreuid ().
+.SH ERRORS
+.TP
+.B EAGAIN
+The call would change the caller's real UID (i.e.,
+.I ruid
+does not match the caller's real UID),
+but there was a temporary failure allocating the
+necessary kernel data structures.
+.TP
+.B EAGAIN
+.I ruid
+does not match the caller's real UID and this call would
+bring the number of processes belonging to the real user ID
+.I ruid
+over the caller's
+.B RLIMIT_NPROC
+resource limit.
+Since Linux 3.1, this error case no longer occurs
+(but robust applications should check for this error);
+see the description of
+.B EAGAIN
+in
+.BR execve (2).
+.TP
+.B EINVAL
+One or more of the target user or group IDs
+is not valid in this user namespace.
+.TP
+.B EPERM
+The calling process is not privileged
+(on Linux, does not have the necessary capability in its user namespace:
+.B CAP_SETUID
+in the case of
+.BR setreuid (),
+or
+.B CAP_SETGID
+in the case of
+.BR setregid ())
+and a change other than (i)
+swapping the effective user (group) ID with the real user (group) ID,
+or (ii) setting one to the value of the other or (iii) setting the
+effective user (group) ID to the value of the
+saved set-user-ID (saved set-group-ID) was specified.
+.SH VERSIONS
+POSIX.1 does not specify all of the UID changes that Linux permits
+for an unprivileged process.
+For
+.BR setreuid (),
+the effective user ID can be made the same as the
+real user ID or the saved set-user-ID,
+and it is unspecified whether unprivileged processes may set the
+real user ID to the real user ID, the effective user ID, or the
+saved set-user-ID.
+For
+.BR setregid (),
+the real group ID can be changed to the value of the saved set-group-ID,
+and the effective group ID can be changed to the value of
+the real group ID or the saved set-group-ID.
+The precise details of what ID changes are permitted vary
+across implementations.
+.P
+POSIX.1 makes no specification about the effect of these calls
+on the saved set-user-ID and saved set-group-ID.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD (first appeared in 4.2BSD).
+.P
+Setting the effective user (group) ID to the
+saved set-user-ID (saved set-group-ID) is
+possible since Linux 1.1.37 (1.1.38).
+.P
+The original Linux
+.BR setreuid ()
+and
+.BR setregid ()
+system calls supported only 16-bit user and group IDs.
+Subsequently, Linux 2.4 added
+.BR setreuid32 ()
+and
+.BR setregid32 (),
+supporting 32-bit IDs.
+The glibc
+.BR setreuid ()
+and
+.BR setregid ()
+wrapper functions transparently deal with the variations across kernel versions.
+.\"
+.SS C library/kernel differences
+At the kernel level, user IDs and group IDs are a per-thread attribute.
+However, POSIX requires that all threads in a process
+share the same credentials.
+The NPTL threading implementation handles the POSIX requirements by
+providing wrapper functions for
+the various system calls that change process UIDs and GIDs.
+These wrapper functions (including those for
+.BR setreuid ()
+and
+.BR setregid ())
+employ a signal-based technique to ensure
+that when one thread changes credentials,
+all of the other threads in the process also change their credentials.
+For details, see
+.BR nptl (7).
+.SH SEE ALSO
+.BR getgid (2),
+.BR getuid (2),
+.BR seteuid (2),
+.BR setgid (2),
+.BR setresuid (2),
+.BR setuid (2),
+.BR capabilities (7),
+.BR credentials (7),
+.BR user_namespaces (7)
diff --git a/man/man2/setreuid32.2 b/man/man2/setreuid32.2
new file mode 100644
index 000000000..ec3ff6416
--- /dev/null
+++ b/man/man2/setreuid32.2
@@ -0,0 +1 @@
+.so man2/setreuid.2
diff --git a/man/man2/setrlimit.2 b/man/man2/setrlimit.2
new file mode 100644
index 000000000..df6d7362a
--- /dev/null
+++ b/man/man2/setrlimit.2
@@ -0,0 +1 @@
+.so man2/getrlimit.2
diff --git a/man/man2/setsid.2 b/man/man2/setsid.2
new file mode 100644
index 000000000..3ee4e2a66
--- /dev/null
+++ b/man/man2/setsid.2
@@ -0,0 +1,100 @@
+.\" Copyright Michael Haardt (michael@cantor.informatik.rwth-aachen.de)
+.\"     Sat Aug 27 20:43:50 MET DST 1994
+.\" and Copyright (C) 2014, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sun Sep 11 19:19:05 1994 <faith@cs.unc.edu>
+.\" Modified Mon Mar 25 10:19:00 1996 <aeb@cwi.nl> (merged a few
+.\"	tiny changes from a man page by Charles Livingston).
+.\" Modified Sun Jul 21 14:45:46 1996 <aeb@cwi.nl>
+.\"
+.TH setsid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setsid \- creates a session and sets the process group ID
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B pid_t setsid(void);
+.fi
+.SH DESCRIPTION
+.BR setsid ()
+creates a new session if the calling process is not a
+process group leader.
+The calling process is the leader of the new session
+(i.e., its session ID is made the same as its process ID).
+The calling process also becomes
+the process group leader of a new process group in the session
+(i.e., its process group ID is made the same as its process ID).
+.P
+The calling process will be the only process in
+the new process group and in the new session.
+.P
+Initially, the new session has no controlling terminal.
+For details of how a session acquires a controlling terminal, see
+.BR credentials (7).
+.SH RETURN VALUE
+On success, the (new) session ID of the calling process is returned.
+On error,
+.I "(pid_t)\ \-1"
+is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EPERM
+The process group ID of any process equals the PID of the calling process.
+Thus, in particular,
+.BR setsid ()
+fails if the calling process is already a process group leader.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.SH NOTES
+A child created via
+.BR fork (2)
+inherits its parent's session ID.
+The session ID is preserved across an
+.BR execve (2).
+.P
+A process group leader is a process whose process group ID equals its PID.
+Disallowing a process group leader from calling
+.BR setsid ()
+prevents the possibility that a process group leader places itself
+in a new session while other processes in the process group remain
+in the original session;
+such a scenario would break the strict
+two-level hierarchy of sessions and process groups.
+In order to be sure that
+.BR setsid ()
+will succeed, call
+.BR fork (2)
+and have the parent
+.BR _exit (2),
+while the child (which by definition can't be a process group leader) calls
+.BR setsid ().
+.P
+If a session has a controlling terminal, and the
+.B CLOCAL
+flag for that terminal is not set,
+and a terminal hangup occurs, then the session leader is sent a
+.B SIGHUP
+signal.
+.P
+If a process that is a session leader terminates, then a
+.B SIGHUP
+signal is sent to each process in the foreground
+process group of the controlling terminal.
+.SH SEE ALSO
+.BR setsid (1),
+.BR getsid (2),
+.BR setpgid (2),
+.BR setpgrp (2),
+.BR tcgetsid (3),
+.BR credentials (7),
+.BR sched (7)
diff --git a/man/man2/setsockopt.2 b/man/man2/setsockopt.2
new file mode 100644
index 000000000..d98c7769b
--- /dev/null
+++ b/man/man2/setsockopt.2
@@ -0,0 +1 @@
+.so man2/getsockopt.2
diff --git a/man/man2/settimeofday.2 b/man/man2/settimeofday.2
new file mode 100644
index 000000000..2b6eff428
--- /dev/null
+++ b/man/man2/settimeofday.2
@@ -0,0 +1 @@
+.so man2/gettimeofday.2
diff --git a/man/man2/setuid.2 b/man/man2/setuid.2
new file mode 100644
index 000000000..2c987c437
--- /dev/null
+++ b/man/man2/setuid.2
@@ -0,0 +1,156 @@
+.\" Copyright (C), 1994, Graeme W. Wilford (Wilf).
+.\" and Copyright (C) 2010, 2014, 2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Fri Jul 29th 12:56:44 BST 1994  Wilf. <G.Wilford@ee.surrey.ac.uk>
+.\" Changes inspired by patch from Richard Kettlewell
+.\"   <richard@greenend.org.uk>, aeb 970616.
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.TH setuid 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setuid \- set user identity
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int setuid(uid_t " uid );
+.fi
+.SH DESCRIPTION
+.BR setuid ()
+sets the effective user ID of the calling process.
+If the calling process is privileged
+(more precisely: if the process has the
+.B CAP_SETUID
+capability in its user namespace),
+the real UID and saved set-user-ID are also set.
+.P
+Under Linux,
+.BR setuid ()
+is implemented like the POSIX version with the
+.B _POSIX_SAVED_IDS
+feature.
+This allows a set-user-ID (other than root) program to drop all of its user
+privileges, do some un-privileged work, and then reengage the original
+effective user ID in a secure manner.
+.P
+If the user is root or the program is set-user-ID-root, special care must be
+taken:
+.BR setuid ()
+checks the effective user ID of the caller and if it is
+the superuser, all process-related user ID's are set to
+.IR uid .
+After this has occurred, it is impossible for the program to regain root
+privileges.
+.P
+Thus, a set-user-ID-root program wishing to temporarily drop root
+privileges, assume the identity of an unprivileged user, and then regain
+root privileges afterward cannot use
+.BR setuid ().
+You can accomplish this with
+.BR seteuid (2).
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+.IR Note :
+there are cases where
+.BR setuid ()
+can fail even when the caller is UID 0;
+it is a grave security error to omit checking for a failure return from
+.BR setuid ().
+.SH ERRORS
+.TP
+.B EAGAIN
+The call would change the caller's real UID (i.e.,
+.I uid
+does not match the caller's real UID),
+but there was a temporary failure allocating the
+necessary kernel data structures.
+.TP
+.B EAGAIN
+.I uid
+does not match the real user ID of the caller and this call would
+bring the number of processes belonging to the real user ID
+.I uid
+over the caller's
+.B RLIMIT_NPROC
+resource limit.
+Since Linux 3.1, this error case no longer occurs
+(but robust applications should check for this error);
+see the description of
+.B EAGAIN
+in
+.BR execve (2).
+.TP
+.B EINVAL
+The user ID specified in
+.I uid
+is not valid in this user namespace.
+.TP
+.B EPERM
+The user is not privileged (Linux: does not have the
+.B CAP_SETUID
+capability in its user namespace) and
+.I uid
+does not match the real UID or saved set-user-ID of the calling process.
+.SH VERSIONS
+.SS C library/kernel differences
+At the kernel level, user IDs and group IDs are a per-thread attribute.
+However, POSIX requires that all threads in a process
+share the same credentials.
+The NPTL threading implementation handles the POSIX requirements by
+providing wrapper functions for
+the various system calls that change process UIDs and GIDs.
+These wrapper functions (including the one for
+.BR setuid ())
+employ a signal-based technique to ensure
+that when one thread changes credentials,
+all of the other threads in the process also change their credentials.
+For details, see
+.BR nptl (7).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.P
+Not quite compatible with the 4.4BSD call, which
+sets all of the real, saved, and effective user IDs.
+.\" SVr4 documents an additional EINVAL error condition.
+.P
+The original Linux
+.BR setuid ()
+system call supported only 16-bit user IDs.
+Subsequently, Linux 2.4 added
+.BR setuid32 ()
+supporting 32-bit IDs.
+The glibc
+.BR setuid ()
+wrapper function transparently deals with the variation across kernel versions.
+.SH NOTES
+Linux has the concept of the filesystem user ID, normally equal to the
+effective user ID.
+The
+.BR setuid ()
+call also sets the filesystem user ID of the calling process.
+See
+.BR setfsuid (2).
+.P
+If
+.I uid
+is different from the old effective UID, the process will
+be forbidden from leaving core dumps.
+.SH SEE ALSO
+.BR getuid (2),
+.BR seteuid (2),
+.BR setfsuid (2),
+.BR setreuid (2),
+.BR capabilities (7),
+.BR credentials (7),
+.BR user_namespaces (7)
diff --git a/man/man2/setuid32.2 b/man/man2/setuid32.2
new file mode 100644
index 000000000..24656c29f
--- /dev/null
+++ b/man/man2/setuid32.2
@@ -0,0 +1 @@
+.so man2/setuid.2
diff --git a/man/man2/setup.2 b/man/man2/setup.2
new file mode 100644
index 000000000..9fb5e8654
--- /dev/null
+++ b/man/man2/setup.2
@@ -0,0 +1,55 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified Sun Jul 25 10:14:13 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 15 April 1995 by Michael Chastain <mec@shell.portal.com>
+.\"   Update calling parameters to Linux 1.2.4 values.
+.\" Modified 10 June 1995 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 3 May 1996 by Martin Schulze <joey@infodrom.north.de>
+.\" Modified Wed Nov  6 04:05:28 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Sat Jan 29 01:08:23 2000 by aeb
+.\"
+.TH setup 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setup \- setup devices and filesystems, mount root filesystem
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B [[deprecated]] int setup(void);
+.fi
+.SH DESCRIPTION
+.BR setup ()
+is called once from within
+.IR linux/init/main.c .
+It calls initialization functions for devices and filesystems
+configured into the kernel and then mounts the root filesystem.
+.P
+No user process may call
+.BR setup ().
+Any user process, even a process with superuser permission,
+will receive
+.BR EPERM .
+.SH RETURN VALUE
+.BR setup ()
+always returns \-1 for a user process.
+.SH ERRORS
+.TP
+.B EPERM
+Always, for a user process.
+.SH STANDARDS
+Linux.
+.SH VERSIONS
+Removed in Linux 2.1.121.
+.P
+The calling sequence varied: at some times
+.BR setup ()
+has had a single argument
+.I "void\ *BIOS"
+and at other times a single argument
+.IR "int magic" .
diff --git a/man/man2/setxattr.2 b/man/man2/setxattr.2
new file mode 100644
index 000000000..ebb4229f0
--- /dev/null
+++ b/man/man2/setxattr.2
@@ -0,0 +1,159 @@
+.\" Copyright (C) Andreas Gruenbacher, February 2001
+.\" Copyright (C) Silicon Graphics Inc, September 2001
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH setxattr 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setxattr, lsetxattr, fsetxattr \- set an extended attribute value
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/xattr.h>
+.P
+.BI "int setxattr(const char *" path ", const char *" name ,
+.BI "              const void " value [. size "], size_t " size ", int " flags );
+.BI "int lsetxattr(const char *" path ", const char *" name ,
+.BI "              const void " value [. size "], size_t " size ", int " flags );
+.BI "int fsetxattr(int " fd ", const char *" name ,
+.BI "              const void " value [. size "], size_t " size ", int " flags );
+.fi
+.SH DESCRIPTION
+Extended attributes are
+.IR name : value
+pairs associated with inodes (files, directories, symbolic links, etc.).
+They are extensions to the normal attributes which are associated
+with all inodes in the system (i.e., the
+.BR stat (2)
+data).
+A complete overview of extended attributes concepts can be found in
+.BR xattr (7).
+.P
+.BR setxattr ()
+sets the
+.I value
+of the extended attribute identified by
+.I name
+and associated with the given
+.I path
+in the filesystem.
+The
+.I size
+argument specifies the size (in bytes) of
+.IR value ;
+a zero-length value is permitted.
+.P
+.BR lsetxattr ()
+is identical to
+.BR setxattr (),
+except in the case of a symbolic link, where the extended attribute is
+set on the link itself, not the file that it refers to.
+.P
+.BR fsetxattr ()
+is identical to
+.BR setxattr (),
+only the extended attribute is set on the open file referred to by
+.I fd
+(as returned by
+.BR open (2))
+in place of
+.IR path .
+.P
+An extended attribute name is a null-terminated string.
+The
+.I name
+includes a namespace prefix; there may be several, disjoint
+namespaces associated with an individual inode.
+The
+.I value
+of an extended attribute is a chunk of arbitrary textual or
+binary data of specified length.
+.P
+By default
+(i.e.,
+.I flags
+is zero),
+the extended attribute will be created if it does not exist,
+or the value will be replaced if the attribute already exists.
+To modify these semantics, one of the following values can be specified in
+.IR flags :
+.TP
+.B XATTR_CREATE
+Perform a pure create, which fails if the named attribute exists already.
+.TP
+.B XATTR_REPLACE
+Perform a pure replace operation,
+which fails if the named attribute does not already exist.
+.SH RETURN VALUE
+On success, zero is returned.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EDQUOT
+Disk quota limits meant that
+there is insufficient space remaining to store the extended attribute.
+.TP
+.B EEXIST
+.B XATTR_CREATE
+was specified, and the attribute exists already.
+.TP
+.B ENODATA
+.B XATTR_REPLACE
+was specified, and the attribute does not exist.
+.\" .RB ( ENOATTR
+.\" is defined to be a synonym for
+.\" .BR ENODATA
+.\" in
+.\" .IR <attr/attributes.h> .)
+.TP
+.B ENOSPC
+There is insufficient space remaining to store the extended attribute.
+.TP
+.B ENOTSUP
+The namespace prefix of
+.I name
+is not valid.
+.TP
+.B ENOTSUP
+Extended attributes are not supported by the filesystem, or are disabled,
+.TP
+.B EPERM
+The file is marked immutable or append-only.
+(See
+.BR ioctl_iflags (2).)
+.P
+In addition, the errors documented in
+.BR stat (2)
+can also occur.
+.TP
+.B ERANGE
+The size of
+.I name
+or
+.I value
+exceeds a filesystem-specific limit.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.4,
+glibc 2.3.
+.\" .SH AUTHORS
+.\" Andreas Gruenbacher,
+.\" .RI < a.gruenbacher@computer.org >
+.\" and the SGI XFS development team,
+.\" .RI < linux-xfs@oss.sgi.com >.
+.\" Please send any bug reports or comments to these addresses.
+.SH SEE ALSO
+.BR getfattr (1),
+.BR setfattr (1),
+.BR getxattr (2),
+.BR listxattr (2),
+.BR open (2),
+.BR removexattr (2),
+.BR stat (2),
+.BR symlink (7),
+.BR xattr (7)
diff --git a/man/man2/sgetmask.2 b/man/man2/sgetmask.2
new file mode 100644
index 000000000..9cf17b8d4
--- /dev/null
+++ b/man/man2/sgetmask.2
@@ -0,0 +1,70 @@
+.\" Copyright (c) 2007 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sgetmask 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sgetmask, ssetmask \- manipulation of signal mask (obsolete)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.B [[deprecated]] long syscall(SYS_sgetmask, void);
+.BI "[[deprecated]] long syscall(SYS_ssetmask, long " newmask );
+.fi
+.SH DESCRIPTION
+These system calls are obsolete.
+.IR "Do not use them" ;
+use
+.BR sigprocmask (2)
+instead.
+.P
+.BR sgetmask ()
+returns the signal mask of the calling process.
+.P
+.BR ssetmask ()
+sets the signal mask of the calling process to the value given in
+.IR newmask .
+The previous signal mask is returned.
+.P
+The signal masks dealt with by these two system calls
+are plain bit masks (unlike the
+.I sigset_t
+used by
+.BR sigprocmask (2));
+use
+.BR sigmask (3)
+to create and inspect these masks.
+.SH RETURN VALUE
+.BR sgetmask ()
+always successfully returns the signal mask.
+.BR ssetmask ()
+always succeeds, and returns the previous signal mask.
+.SH ERRORS
+These system calls always succeed.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Since Linux 3.16,
+.\" f6187769dae48234f3877df3c4d99294cc2254fa
+support for these system calls is optional,
+depending on whether the kernel was built with the
+.B CONFIG_SGETMASK_SYSCALL
+option.
+.SH NOTES
+These system calls are unaware of signal numbers greater than 31
+(i.e., real-time signals).
+.P
+These system calls do not exist on x86-64.
+.P
+It is not possible to block
+.B SIGSTOP
+or
+.BR SIGKILL .
+.SH SEE ALSO
+.BR sigprocmask (2),
+.BR signal (7)
diff --git a/man/man2/shmat.2 b/man/man2/shmat.2
new file mode 100644
index 000000000..3f3e5a4bd
--- /dev/null
+++ b/man/man2/shmat.2
@@ -0,0 +1 @@
+.so man2/shmop.2
diff --git a/man/man2/shmctl.2 b/man/man2/shmctl.2
new file mode 100644
index 000000000..986268957
--- /dev/null
+++ b/man/man2/shmctl.2
@@ -0,0 +1,494 @@
+'\" t
+.\" Copyright (c) 1993 Luigi P. Bai (lpb@softint.com) July 28, 1993
+.\" and Copyright 1993 Giorgio Ciucci <giorgio@crcc.it>
+.\" and Copyright 2004, 2005 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-28, Rik Faith <faith@cs.unc.edu>
+.\" Modified 1993-11-28, Giorgio Ciucci <giorgio@crcc.it>
+.\" Modified 1997-01-31, Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-02-18, Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2002-01-05, 2004-05-27, 2004-06-17,
+.\"    Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2004-10-11, aeb
+.\" Modified, Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Updated shmid_ds structure definitions
+.\"	Added information on SHM_DEST and SHM_LOCKED flags
+.\"	Noted that CAP_IPC_LOCK is not required for SHM_UNLOCK
+.\"		since Linux 2.6.9
+.\" Modified, 2004-11-25, mtk, notes on 2.6.9 RLIMIT_MEMLOCK changes
+.\" 2005-04-25, mtk -- noted aberrant Linux behavior w.r.t. new
+.\"	attaches to a segment that has already been marked for deletion.
+.\" 2005-08-02, mtk: Added IPC_INFO, SHM_INFO, SHM_STAT descriptions.
+.\" 2018-03-20, dbueso: Added SHM_STAT_ANY description.
+.\"
+.TH shmctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+shmctl \- System V shared memory control
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/shm.h>
+.P
+.BI "int shmctl(int " shmid ", int " op ", struct shmid_ds *" buf );
+.fi
+.SH DESCRIPTION
+.BR shmctl ()
+performs the control operation specified by
+.I op
+on the System\ V shared memory segment whose identifier is given in
+.IR shmid .
+.P
+The
+.I buf
+argument is a pointer to a \fIshmid_ds\fP structure,
+defined in \fI<sys/shm.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct shmid_ds {
+    struct ipc_perm shm_perm;    /* Ownership and permissions */
+    size_t          shm_segsz;   /* Size of segment (bytes) */
+    time_t          shm_atime;   /* Last attach time */
+    time_t          shm_dtime;   /* Last detach time */
+    time_t          shm_ctime;   /* Creation time/time of last
+                                    modification via shmctl() */
+    pid_t           shm_cpid;    /* PID of creator */
+    pid_t           shm_lpid;    /* PID of last shmat(2)/shmdt(2) */
+    shmatt_t        shm_nattch;  /* No. of current attaches */
+    ...
+};
+.EE
+.in
+.P
+The fields of the
+.I shmid_ds
+structure are as follows:
+.TP 12
+.I shm_perm
+This is an
+.I ipc_perm
+structure (see below) that specifies the access permissions
+on the shared memory segment.
+.TP
+.I shm_segsz
+Size in bytes of the shared memory segment.
+.TP
+.I shm_atime
+Time of the last
+.BR shmat (2)
+system call that attached this segment.
+.TP
+.I shm_dtime
+Time of the last
+.BR shmdt (2)
+system call that detached tgis segment.
+.TP
+.I shm_ctime
+Time of creation of segment or time of the last
+.BR shmctl ()
+.B IPC_SET
+operation.
+.TP
+.I shm_cpid
+ID of the process that created the shared memory segment.
+.TP
+.I shm_lpid
+ID of the last process that executed a
+.BR shmat (2)
+or
+.BR shmdt (2)
+system call on this segment.
+.TP
+.I shm_nattch
+Number of processes that have this segment attached.
+.P
+The
+.I ipc_perm
+structure is defined as follows
+(the highlighted fields are settable using
+.BR IPC_SET ):
+.P
+.in +4n
+.EX
+struct ipc_perm {
+    key_t          __key;    /* Key supplied to shmget(2) */
+    uid_t          \fBuid\fP;      /* Effective UID of owner */
+    gid_t          \fBgid\fP;      /* Effective GID of owner */
+    uid_t          cuid;     /* Effective UID of creator */
+    gid_t          cgid;     /* Effective GID of creator */
+    unsigned short \fBmode\fP;     /* \fBPermissions\fP + SHM_DEST and
+                                SHM_LOCKED flags */
+    unsigned short __seq;    /* Sequence number */
+};
+.EE
+.in
+.P
+The least significant 9 bits of the
+.I mode
+field of the
+.I ipc_perm
+structure define the access permissions for the shared memory segment.
+The permission bits are as follows:
+.TS
+l l.
+0400	Read by user
+0200	Write by user
+0040	Read by group
+0020	Write by group
+0004	Read by others
+0002	Write by others
+.TE
+.P
+Bits 0100, 0010, and 0001 (the execute bits) are unused by the system.
+(It is not necessary to have execute permission on a segment
+in order to perform a
+.BR shmat (2)
+call with the
+.B SHM_EXEC
+flag.)
+.P
+Valid values for
+.I op
+are:
+.TP
+.B IPC_STAT
+Copy information from the kernel data structure associated with
+.I shmid
+into the
+.I shmid_ds
+structure pointed to by \fIbuf\fP.
+The caller must have read permission on the
+shared memory segment.
+.TP
+.B IPC_SET
+Write the values of some members of the
+.I shmid_ds
+structure pointed to by
+.I buf
+to the kernel data structure associated with this shared memory segment,
+updating also its
+.I shm_ctime
+member.
+.IP
+The following fields are updated:
+\fIshm_perm.uid\fP, \fIshm_perm.gid\fP,
+and (the least significant 9 bits of) \fIshm_perm.mode\fP.
+.IP
+The effective UID of the calling process must match the owner
+.RI ( shm_perm.uid )
+or creator
+.RI ( shm_perm.cuid )
+of the shared memory segment, or the caller must be privileged.
+.TP
+.B IPC_RMID
+Mark the segment to be destroyed.
+The segment will actually be destroyed
+only after the last process detaches it (i.e., when the
+.I shm_nattch
+member of the associated structure
+.I shmid_ds
+is zero).
+The caller must be the owner or creator of the segment, or be privileged.
+The
+.I buf
+argument is ignored.
+.IP
+If a segment has been marked for destruction, then the (nonstandard)
+.B SHM_DEST
+flag of the
+.I shm_perm.mode
+field in the associated data structure retrieved by
+.B IPC_STAT
+will be set.
+.IP
+The caller \fImust\fP ensure that a segment is eventually destroyed;
+otherwise its pages that were faulted in will remain in memory or swap.
+.IP
+See also the description of
+.I  /proc/sys/kernel/shm_rmid_forced
+in
+.BR proc (5).
+.TP
+.BR IPC_INFO " (Linux-specific)"
+Return information about system-wide shared memory limits and
+parameters in the structure pointed to by
+.IR buf .
+This structure is of type
+.I shminfo
+(thus, a cast is required),
+defined in
+.I <sys/shm.h>
+if the
+.B _GNU_SOURCE
+feature test macro is defined:
+.IP
+.in +4n
+.EX
+struct shminfo {
+    unsigned long shmmax; /* Maximum segment size */
+    unsigned long shmmin; /* Minimum segment size;
+                             always 1 */
+    unsigned long shmmni; /* Maximum number of segments */
+    unsigned long shmseg; /* Maximum number of segments
+                             that a process can attach;
+                             unused within kernel */
+    unsigned long shmall; /* Maximum number of pages of
+                             shared memory, system\-wide */
+};
+.EE
+.in
+.IP
+The
+.IR shmmni ,
+.IR shmmax ,
+and
+.I shmall
+settings can be changed via
+.I /proc
+files of the same name; see
+.BR proc (5)
+for details.
+.TP
+.BR SHM_INFO " (Linux-specific)"
+Return a
+.I shm_info
+structure whose fields contain information
+about system resources consumed by shared memory.
+This structure is defined in
+.I <sys/shm.h>
+if the
+.B _GNU_SOURCE
+feature test macro is defined:
+.IP
+.in +4n
+.EX
+struct shm_info {
+    int           used_ids; /* # of currently existing
+                               segments */
+    unsigned long shm_tot;  /* Total number of shared
+                               memory pages */
+    unsigned long shm_rss;  /* # of resident shared
+                               memory pages */
+    unsigned long shm_swp;  /* # of swapped shared
+                               memory pages */
+    unsigned long swap_attempts;
+                            /* Unused since Linux 2.4 */
+    unsigned long swap_successes;
+                            /* Unused since Linux 2.4 */
+};
+.EE
+.in
+.TP
+.BR SHM_STAT " (Linux-specific)"
+Return a
+.I shmid_ds
+structure as for
+.BR IPC_STAT .
+However, the
+.I shmid
+argument is not a segment identifier, but instead an index into
+the kernel's internal array that maintains information about
+all shared memory segments on the system.
+.TP
+.BR SHM_STAT_ANY " (Linux-specific, since Linux 4.17)"
+Return a
+.I shmid_ds
+structure as for
+.BR SHM_STAT .
+However,
+.I shm_perm.mode
+is not checked for read access for
+.IR shmid ,
+meaning that any user can employ this operation (just as any user may read
+.I /proc/sysvipc/shm
+to obtain the same information).
+.P
+The caller can prevent or allow swapping of a shared
+memory segment with the following
+.I op
+values:
+.TP
+.BR SHM_LOCK " (Linux-specific)"
+Prevent swapping of the shared memory segment.
+The caller must fault in
+any pages that are required to be present after locking is enabled.
+If a segment has been locked, then the (nonstandard)
+.B SHM_LOCKED
+flag of the
+.I shm_perm.mode
+field in the associated data structure retrieved by
+.B IPC_STAT
+will be set.
+.TP
+.BR SHM_UNLOCK " (Linux-specific)"
+Unlock the segment, allowing it to be swapped out.
+.P
+Before Linux 2.6.10, only a privileged process
+could employ
+.B SHM_LOCK
+and
+.BR SHM_UNLOCK .
+Since Linux 2.6.10, an unprivileged process can employ these operations
+if its effective UID matches the owner or creator UID of the segment, and
+(for
+.BR SHM_LOCK )
+the amount of memory to be locked falls within the
+.B RLIMIT_MEMLOCK
+resource limit (see
+.BR setrlimit (2)).
+.\" There was some weirdness in Linux 2.6.9: SHM_LOCK and SHM_UNLOCK could
+.\" be applied to a segment, regardless of ownership of the segment.
+.\" This was a botch-up in the move to RLIMIT_MEMLOCK, and was fixed
+.\" in Linux 2.6.10.  MTK, May 2005
+.SH RETURN VALUE
+A successful
+.B IPC_INFO
+or
+.B SHM_INFO
+operation returns the index of the highest used entry in the
+kernel's internal array recording information about all
+shared memory segments.
+(This information can be used with repeated
+.B SHM_STAT
+or
+.B SHM_STAT_ANY
+operations to obtain information about all shared memory segments
+on the system.)
+A successful
+.B SHM_STAT
+operation returns the identifier of the shared memory segment
+whose index was given in
+.IR shmid .
+Other operations return 0 on success.
+.P
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+\fBIPC_STAT\fP or \fBSHM_STAT\fP is requested and
+\fIshm_perm.mode\fP does not allow read access for
+.IR shmid ,
+and the calling process does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EFAULT
+The argument
+.I op
+has value
+.B IPC_SET
+or
+.B IPC_STAT
+but the address pointed to by
+.I buf
+isn't accessible.
+.TP
+.B EIDRM
+\fIshmid\fP points to a removed identifier.
+.TP
+.B EINVAL
+.I shmid
+is not a valid identifier, or
+.I op
+is not a valid operation.
+Or: for a
+.B SHM_STAT
+or
+.B SHM_STAT_ANY
+operation, the index value specified in
+.I shmid
+referred to an array slot that is currently unused.
+.TP
+.B ENOMEM
+(Since Linux 2.6.9),
+.B SHM_LOCK
+was specified and the size of the to-be-locked segment would mean
+that the total bytes in locked shared memory segments would exceed
+the limit for the real user ID of the calling process.
+This limit is defined by the
+.B RLIMIT_MEMLOCK
+soft resource limit (see
+.BR setrlimit (2)).
+.TP
+.B EOVERFLOW
+\fBIPC_STAT\fP is attempted, and the GID or UID value
+is too large to be stored in the structure pointed to by
+.IR buf .
+.TP
+.B EPERM
+\fBIPC_SET\fP or \fBIPC_RMID\fP is attempted, and the
+effective user ID of the calling process is not that of the creator
+(found in
+.IR shm_perm.cuid ),
+or the owner
+(found in
+.IR shm_perm.uid ),
+and the process was not privileged (Linux: did not have the
+.B CAP_SYS_ADMIN
+capability).
+.IP
+Or (before Linux 2.6.9),
+.B SHM_LOCK
+or
+.B SHM_UNLOCK
+was specified, but the process was not privileged
+(Linux: did not have the
+.B CAP_IPC_LOCK
+capability).
+(Since Linux 2.6.9, this error can also occur if the
+.B RLIMIT_MEMLOCK
+is 0 and the caller is not privileged.)
+.SH VERSIONS
+Linux permits a process to attach
+.RB ( shmat (2))
+a shared memory segment that has already been marked for deletion
+using
+.IR shmctl(IPC_RMID) .
+This feature is not available on other UNIX implementations;
+portable applications should avoid relying on it.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.\" SVr4 documents additional error conditions EINVAL,
+.\" ENOENT, ENOSPC, ENOMEM, EEXIST.  Neither SVr4 nor SVID documents
+.\" an EIDRM error condition.
+.P
+Various fields in a \fIstruct shmid_ds\fP were typed as
+.I short
+under Linux 2.2
+and have become
+.I long
+under Linux 2.4.
+To take advantage of this,
+a recompilation under glibc-2.1.91 or later should suffice.
+(The kernel distinguishes old and new calls by an
+.B IPC_64
+flag in
+.IR op .)
+.SH NOTES
+The
+.BR IPC_INFO ,
+.BR SHM_STAT ,
+and
+.B SHM_INFO
+operations are used by the
+.BR ipcs (1)
+program to provide information on allocated resources.
+In the future, these may modified or moved to a
+.I /proc
+filesystem interface.
+.SH SEE ALSO
+.BR mlock (2),
+.BR setrlimit (2),
+.BR shmget (2),
+.BR shmop (2),
+.BR capabilities (7),
+.BR sysvipc (7)
diff --git a/man/man2/shmdt.2 b/man/man2/shmdt.2
new file mode 100644
index 000000000..3f3e5a4bd
--- /dev/null
+++ b/man/man2/shmdt.2
@@ -0,0 +1 @@
+.so man2/shmop.2
diff --git a/man/man2/shmget.2 b/man/man2/shmget.2
new file mode 100644
index 000000000..96c2e6108
--- /dev/null
+++ b/man/man2/shmget.2
@@ -0,0 +1,412 @@
+.\" Copyright (c) 1993 Luigi P. Bai (lpb@softint.com) July 28, 1993
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 28 10:57:35 1993, Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Nov 28 16:43:30 1993, Rik Faith <faith@cs.unc.edu>
+.\"          with material from Giorgio Ciucci <giorgio@crcc.it>
+.\" Portions Copyright 1993 Giorgio Ciucci <giorgio@crcc.it>
+.\" Modified Tue Oct 22 22:03:17 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified, 8 Jan 2003, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"	Removed EIDRM from errors - that can't happen...
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Added notes on /proc files
+.\"
+.TH shmget 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+shmget \- allocates a System V shared memory segment
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/shm.h>
+.P
+.BI "int shmget(key_t " key ", size_t " size ", int " shmflg );
+.fi
+.SH DESCRIPTION
+.BR shmget ()
+returns the identifier of the System\ V shared memory segment
+associated with the value of the argument
+.IR key .
+It may be used either to obtain the identifier of a previously created
+shared memory segment (when
+.I shmflg
+is zero and
+.I key
+does not have the value
+.BR IPC_PRIVATE ),
+or to create a new set.
+.P
+A new shared memory segment, with size equal to the value of
+.I size
+rounded up to a multiple of
+.BR PAGE_SIZE ,
+is created if
+.I key
+has the value
+.B IPC_PRIVATE
+or
+.I key
+isn't
+.BR IPC_PRIVATE ,
+no shared memory segment corresponding to
+.I key
+exists, and
+.B IPC_CREAT
+is specified in
+.IR shmflg .
+.P
+If
+.I shmflg
+specifies both
+.B IPC_CREAT
+and
+.B IPC_EXCL
+and a shared memory segment already exists for
+.IR key ,
+then
+.BR shmget ()
+fails with
+.I errno
+set to
+.BR EEXIST .
+(This is analogous to the effect of the combination
+.B O_CREAT | O_EXCL
+for
+.BR open (2).)
+.P
+The value
+.I shmflg
+is composed of:
+.TP
+.B IPC_CREAT
+Create a new segment.
+If this flag is not used, then
+.BR shmget ()
+will find the segment associated with \fIkey\fP and check to see if
+the user has permission to access the segment.
+.TP
+.B IPC_EXCL
+This flag is used with
+.B IPC_CREAT
+to ensure that this call creates the segment.
+If the segment already exists, the call fails.
+.TP
+.BR SHM_HUGETLB " (since Linux 2.6)"
+Allocate the segment using "huge" pages.
+See the Linux kernel source file
+.I Documentation/admin\-guide/mm/hugetlbpage.rst
+for further information.
+.TP
+.B SHM_HUGE_2MB
+.TQ
+.BR SHM_HUGE_1GB " (since Linux 3.8)"
+.\" See https://lwn.net/Articles/533499/
+Used in conjunction with
+.B SHM_HUGETLB
+to select alternative hugetlb page sizes (respectively, 2\ MB and 1\ GB)
+on systems that support multiple hugetlb page sizes.
+.IP
+More generally, the desired huge page size can be configured by encoding
+the base-2 logarithm of the desired page size in the six bits at the offset
+.BR SHM_HUGE_SHIFT .
+Thus, the above two constants are defined as:
+.IP
+.in +4n
+.EX
+#define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
+#define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
+.EE
+.in
+.IP
+For some additional details,
+see the discussion of the similarly named constants in
+.BR mmap (2).
+.TP
+.BR SHM_NORESERVE " (since Linux 2.6.15)"
+This flag serves the same purpose as the
+.BR mmap (2)
+.B MAP_NORESERVE
+flag.
+Do not reserve swap space for this segment.
+When swap space is reserved, one has the guarantee
+that it is possible to modify the segment.
+When swap space is not reserved one might get
+.B SIGSEGV
+upon a write
+if no physical memory is available.
+See also the discussion of the file
+.I /proc/sys/vm/overcommit_memory
+in
+.BR proc (5).
+.\" As at 2.6.17-rc2, this flag has no effect if SHM_HUGETLB was also
+.\" specified.
+.P
+In addition to the above flags, the least significant 9 bits of
+.I shmflg
+specify the permissions granted to the owner, group, and others.
+These bits have the same format, and the same
+meaning, as the
+.I mode
+argument of
+.BR open (2).
+Presently, execute permissions are not used by the system.
+.P
+When a new shared memory segment is created,
+its contents are initialized to zero values, and
+its associated data structure,
+.I shmid_ds
+(see
+.BR shmctl (2)),
+is initialized as follows:
+.IP \[bu] 3
+.I shm_perm.cuid
+and
+.I shm_perm.uid
+are set to the effective user ID of the calling process.
+.IP \[bu]
+.I shm_perm.cgid
+and
+.I shm_perm.gid
+are set to the effective group ID of the calling process.
+.IP \[bu]
+The least significant 9 bits of
+.I shm_perm.mode
+are set to the least significant 9 bit of
+.IR shmflg .
+.IP \[bu]
+.I shm_segsz
+is set to the value of
+.IR size .
+.IP \[bu]
+.IR shm_lpid ,
+.IR shm_nattch ,
+.IR shm_atime ,
+and
+.I shm_dtime
+are set to 0.
+.IP \[bu]
+.I shm_ctime
+is set to the current time.
+.P
+If the shared memory segment already exists, the permissions are
+verified, and a check is made to see if it is marked for destruction.
+.SH RETURN VALUE
+On success, a valid shared memory identifier is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The user does not have permission to access the
+shared memory segment, and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EEXIST
+.B IPC_CREAT
+and
+.B IPC_EXCL
+were specified in
+.IR shmflg ,
+but a shared memory segment already exists for
+.IR key .
+.TP
+.B EINVAL
+A new segment was to be created and
+.I size
+is less than
+.B SHMMIN
+or greater than
+.BR SHMMAX .
+.TP
+.B EINVAL
+A segment for the given
+.I key
+exists, but \fIsize\fP is greater than the size
+of that segment.
+.TP
+.B ENFILE
+.\" [2.6.7] shmem_zero_setup()-->shmem_file_setup()-->get_empty_filp()
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+No segment exists for the given \fIkey\fP, and
+.B IPC_CREAT
+was not specified.
+.TP
+.B ENOMEM
+No memory could be allocated for segment overhead.
+.TP
+.B ENOSPC
+All possible shared memory IDs have been taken
+.RB ( SHMMNI ),
+or allocating a segment of the requested
+.I size
+would cause the system to exceed the system-wide limit on shared memory
+.RB ( SHMALL ).
+.TP
+.B EPERM
+The
+.B SHM_HUGETLB
+flag was specified, but the caller was not privileged (did not have the
+.B CAP_IPC_LOCK
+capability)
+and is not a member of the
+.I sysctl_hugetlb_shm_group
+group; see the description of
+.I /proc/sys/vm/sysctl_hugetlb_shm_group
+in
+.BR proc (5).
+.SH STANDARDS
+POSIX.1-2008.
+.P
+.B SHM_HUGETLB
+and
+.B SHM_NORESERVE
+are Linux extensions.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.\" SVr4 documents an additional error condition EEXIST.
+.SH NOTES
+.B IPC_PRIVATE
+isn't a flag field but a
+.I key_t
+type.
+If this special value is used for
+.IR key ,
+the system call ignores all but the least significant 9 bits of
+.I shmflg
+and creates a new shared memory segment.
+.\"
+.SS Shared memory limits
+The following limits on shared memory segment resources affect the
+.BR shmget ()
+call:
+.TP
+.B SHMALL
+System-wide limit on the total amount of shared memory,
+measured in units of the system page size.
+.IP
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/shmall .
+Since Linux 3.16,
+.\" commit 060028bac94bf60a65415d1d55a359c3a17d5c31
+the default value for this limit is:
+.IP
+.in +4n
+.EX
+ULONG_MAX - 2\[ha]24
+.EE
+.in
+.IP
+The effect of this value
+(which is suitable for both 32-bit and 64-bit systems)
+is to impose no limitation on allocations.
+This value, rather than
+.BR ULONG_MAX ,
+was chosen as the default to prevent some cases where historical
+applications simply raised the existing limit without first checking
+its current value.
+Such applications would cause the value to overflow if the limit was set at
+.BR ULONG_MAX .
+.IP
+From Linux 2.4 up to Linux 3.15,
+the default value for this limit was:
+.IP
+.in +4n
+.EX
+SHMMAX / PAGE_SIZE * (SHMMNI / 16)
+.EE
+.in
+.IP
+If
+.B SHMMAX
+and
+.B SHMMNI
+were not modified, then multiplying the result of this formula
+by the page size (to get a value in bytes) yielded a value of 8\ GB
+as the limit on the total memory used by all shared memory segments.
+.TP
+.B SHMMAX
+Maximum size in bytes for a shared memory segment.
+.IP
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/shmmax .
+Since Linux 3.16,
+.\" commit 060028bac94bf60a65415d1d55a359c3a17d5c31
+the default value for this limit is:
+.IP
+.in +4n
+.EX
+ULONG_MAX - 2\[ha]24
+.EE
+.in
+.IP
+The effect of this value
+(which is suitable for both 32-bit and 64-bit systems)
+is to impose no limitation on allocations.
+See the description of
+.B SHMALL
+for a discussion of why this default value (rather than
+.BR ULONG_MAX )
+is used.
+.IP
+From Linux 2.2 up to Linux 3.15, the default value of
+this limit was 0x2000000 (32\ MiB).
+.IP
+Because it is not possible to map just part of a shared memory segment,
+the amount of virtual memory places another limit on the maximum size of a
+usable segment:
+for example, on i386 the largest segments that can be mapped have a
+size of around 2.8\ GB, and on x86-64 the limit is around 127 TB.
+.TP
+.B SHMMIN
+Minimum size in bytes for a shared memory segment: implementation
+dependent (currently 1 byte, though
+.B PAGE_SIZE
+is the effective minimum size).
+.TP
+.B SHMMNI
+System-wide limit on the number of shared memory segments.
+In Linux 2.2, the default value for this limit was 128;
+since Linux 2.4, the default value is 4096.
+.IP
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/shmmni .
+.\" Kernels between Linux 2.4.x and Linux 2.6.8 had an off-by-one error
+.\" that meant that we could create one more segment than SHMMNI -- MTK
+.\" This /proc file is not available in Linux 2.2 and earlier -- MTK
+.P
+The implementation has no specific limits for the per-process maximum
+number of shared memory segments
+.RB ( SHMSEG ).
+.SS Linux notes
+Until Linux 2.3.30, Linux would return
+.B EIDRM
+for a
+.BR shmget ()
+on a shared memory segment scheduled for deletion.
+.SH BUGS
+The name choice
+.B IPC_PRIVATE
+was perhaps unfortunate,
+.B IPC_NEW
+would more clearly show its function.
+.SH EXAMPLES
+See
+.BR shmop (2).
+.SH SEE ALSO
+.BR memfd_create (2),
+.BR shmat (2),
+.BR shmctl (2),
+.BR shmdt (2),
+.BR ftok (3),
+.BR capabilities (7),
+.BR shm_overview (7),
+.BR sysvipc (7)
diff --git a/man/man2/shmop.2 b/man/man2/shmop.2
new file mode 100644
index 000000000..9d0acf7f5
--- /dev/null
+++ b/man/man2/shmop.2
@@ -0,0 +1,508 @@
+.\" Copyright 1993 Giorgio Ciucci (giorgio@crcc.it)
+.\" and Copyright 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sun Nov 28 17:06:19 1993, Rik Faith (faith@cs.unc.edu)
+.\"          with material from Luigi P. Bai (lpb@softint.com)
+.\" Portions Copyright 1993 Luigi P. Bai
+.\" Modified Tue Oct 22 22:04:23 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified, 5 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified, 19 Sep 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added SHM_REMAP flag description
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Language and formatting clean-ups
+.\"	Changed wording and placement of sentence regarding attachment
+.\"		of segments marked for destruction
+.\"
+.TH SHMOP 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+shmat, shmdt \- System V shared memory operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/shm.h>
+.P
+.BI "void *shmat(int " shmid ", const void *_Nullable " shmaddr ", \
+int " shmflg );
+.BI "int shmdt(const void *" shmaddr );
+.fi
+.SH DESCRIPTION
+.SS shmat()
+.BR shmat ()
+attaches the System\ V shared memory segment identified by
+.I shmid
+to the address space of the calling process.
+The attaching address is specified by
+.I shmaddr
+with one of the following criteria:
+.IP \[bu] 3
+If
+.I shmaddr
+is NULL,
+the system chooses a suitable (unused) page-aligned address to attach
+the segment.
+.IP \[bu]
+If
+.I shmaddr
+isn't NULL
+and
+.B SHM_RND
+is specified in
+.IR shmflg ,
+the attach occurs at the address equal to
+.I shmaddr
+rounded down to the nearest multiple of
+.BR SHMLBA .
+.IP \[bu]
+Otherwise,
+.I shmaddr
+must be a page-aligned address at which the attach occurs.
+.P
+In addition to
+.BR SHM_RND ,
+the following flags may be specified in the
+.I shmflg
+bit-mask argument:
+.TP
+.BR SHM_EXEC " (Linux-specific; since Linux 2.6.9)"
+Allow the contents of the segment to be executed.
+The caller must have execute permission on the segment.
+.TP
+.B SHM_RDONLY
+Attach the segment for read-only access.
+The process must have read permission for the segment.
+If this flag is not specified,
+the segment is attached for read and write access,
+and the process must have read and write permission for the segment.
+There is no notion of a write-only shared memory segment.
+.TP
+.BR SHM_REMAP " (Linux-specific)"
+This flag specifies
+that the mapping of the segment should replace
+any existing mapping in the range starting at
+.I shmaddr
+and continuing for the size of the segment.
+(Normally, an
+.B EINVAL
+error would result if a mapping already exists in this address range.)
+In this case,
+.I shmaddr
+must not be NULL.
+.P
+The
+.BR brk (2)
+value of the calling process is not altered by the attach.
+The segment will automatically be detached at process exit.
+The same segment may be attached as a read and as a read-write
+one, and more than once, in the process's address space.
+.P
+A successful
+.BR shmat ()
+call updates the members of the
+.I shmid_ds
+structure (see
+.BR shmctl (2))
+associated with the shared memory segment as follows:
+.IP \[bu] 3
+.I shm_atime
+is set to the current time.
+.IP \[bu]
+.I shm_lpid
+is set to the process-ID of the calling process.
+.IP \[bu]
+.I shm_nattch
+is incremented by one.
+.\"
+.SS shmdt()
+.BR shmdt ()
+detaches the shared memory segment located at the address specified by
+.I shmaddr
+from the address space of the calling process.
+The to-be-detached segment must be currently
+attached with
+.I shmaddr
+equal to the value returned by the attaching
+.BR shmat ()
+call.
+.P
+On a successful
+.BR shmdt ()
+call, the system updates the members of the
+.I shmid_ds
+structure associated with the shared memory segment as follows:
+.IP \[bu] 3
+.I shm_dtime
+is set to the current time.
+.IP \[bu]
+.I shm_lpid
+is set to the process-ID of the calling process.
+.IP \[bu]
+.I shm_nattch
+is decremented by one.
+If it becomes 0 and the segment is marked for deletion,
+the segment is deleted.
+.SH RETURN VALUE
+On success,
+.BR shmat ()
+returns the address of the attached shared memory segment; on error,
+.I (void\ *)\ \-1
+is returned, and
+.I errno
+is set to indicate the error.
+.P
+On success,
+.BR shmdt ()
+returns 0; on error \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR shmat ()
+can fail with one of the following errors:
+.TP
+.B EACCES
+The calling process does not have the required permissions for
+the requested attach type, and does not have the
+.B CAP_IPC_OWNER
+capability in the user namespace that governs its IPC namespace.
+.TP
+.B EIDRM
+\fIshmid\fP points to a removed identifier.
+.TP
+.B EINVAL
+Invalid
+.I shmid
+value, unaligned (i.e., not page-aligned and \fBSHM_RND\fP was not
+specified) or invalid
+.I shmaddr
+value, or can't attach segment at
+.IR shmaddr ,
+or
+.B SHM_REMAP
+was specified and
+.I shmaddr
+was NULL.
+.TP
+.B ENOMEM
+Could not allocate memory for the descriptor or for the page tables.
+.P
+.BR shmdt ()
+can fail with one of the following errors:
+.TP
+.B EINVAL
+There is no shared memory segment attached at
+.IR shmaddr ;
+or,
+.\" The following since Linux 2.6.17-rc1:
+.I shmaddr
+is not aligned on a page boundary.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.\" SVr4 documents an additional error condition EMFILE.
+.P
+In SVID 3 (or perhaps earlier),
+the type of the \fIshmaddr\fP argument was changed from
+.I "char\ *"
+into
+.IR "const void\ *" ,
+and the returned type of
+.BR shmat ()
+from
+.I "char\ *"
+into
+.IR "void\ *" .
+.SH NOTES
+After a
+.BR fork (2),
+the child inherits the attached shared memory segments.
+.P
+After an
+.BR execve (2),
+all attached shared memory segments are detached from the process.
+.P
+Upon
+.BR _exit (2),
+all attached shared memory segments are detached from the process.
+.P
+Using
+.BR shmat ()
+with
+.I shmaddr
+equal to NULL
+is the preferred, portable way of attaching a shared memory segment.
+Be aware that the shared memory segment attached in this way
+may be attached at different addresses in different processes.
+Therefore, any pointers maintained within the shared memory must be
+made relative (typically to the starting address of the segment),
+rather than absolute.
+.P
+On Linux, it is possible to attach a shared memory segment even if it
+is already marked to be deleted.
+However, POSIX.1 does not specify this behavior and
+many other implementations do not support it.
+.P
+The following system parameter affects
+.BR shmat ():
+.TP
+.B SHMLBA
+Segment low boundary address multiple.
+When explicitly specifying an attach address in a call to
+.BR shmat (),
+the caller should ensure that the address is a multiple of this value.
+This is necessary on some architectures,
+in order either to ensure good CPU cache performance or to ensure that
+different attaches of the same segment have consistent views
+within the CPU cache.
+.B SHMLBA
+is normally some multiple of the system page size.
+(On many Linux architectures,
+.B SHMLBA
+is the same as the system page size.)
+.P
+The implementation places no intrinsic per-process limit on the
+number of shared memory segments
+.RB ( SHMSEG ).
+.SH EXAMPLES
+The two programs shown below exchange a string using a shared memory segment.
+Further details about the programs are given below.
+First, we show a shell session demonstrating their use.
+.P
+In one terminal window, we run the "reader" program,
+which creates a System V shared memory segment and a System V semaphore set.
+The program prints out the IDs of the created objects,
+and then waits for the semaphore to change value.
+.P
+.in +4n
+.EX
+$ \fB./svshm_string_read\fP
+shmid = 1114194; semid = 15
+.EE
+.in
+.P
+In another terminal window, we run the "writer" program.
+The "writer" program takes three command-line arguments:
+the IDs of the shared memory segment and semaphore set created
+by the "reader", and a string.
+It attaches the existing shared memory segment,
+copies the string to the shared memory, and modifies the semaphore value.
+.P
+.in +4n
+.EX
+$ \fB./svshm_string_write 1114194 15 \[aq]Hello, world\[aq]\fP
+.EE
+.in
+.P
+Returning to the terminal where the "reader" is running,
+we see that the program has ceased waiting on the semaphore
+and has printed the string that was copied into the
+shared memory segment by the writer:
+.P
+.in +4n
+.EX
+Hello, world
+.EE
+.in
+.\"
+.SS Program source: svshm_string.h
+The following header file is included by the "reader" and "writer" programs:
+.P
+.in +4n
+.\" SRC BEGIN (svshm_string.h)
+.EX
+/* svshm_string.h
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#ifndef SVSHM_STRING_H
+#define SVSHM_STRING_H
+\&
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/sem.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+union semun {                   /* Used in calls to semctl() */
+    int                 val;
+    struct semid_ds     *buf;
+    unsigned short      *array;
+#if defined(__linux__)
+    struct seminfo      *__buf;
+#endif
+};
+\&
+#define MEM_SIZE 4096
+\&
+#endif  // include guard
+.EE
+.\" SRC END
+.in
+.\"
+.SS Program source: svshm_string_read.c
+The "reader" program creates a shared memory segment and a semaphore set
+containing one semaphore.
+It then attaches the shared memory object into its address space
+and initializes the semaphore value to 1.
+Finally, the program waits for the semaphore value to become 0,
+and afterwards prints the string that has been copied into the
+shared memory segment by the "writer".
+.P
+.in +4n
+.\" SRC BEGIN (svshm_string_read.c)
+.EX
+/* svshm_string_read.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+\&
+#include "svshm_string.h"
+\&
+int
+main(void)
+{
+    int            semid, shmid;
+    char           *addr;
+    union semun    arg, dummy;
+    struct sembuf  sop;
+\&
+    /* Create shared memory and semaphore set containing one
+       semaphore. */
+\&
+    shmid = shmget(IPC_PRIVATE, MEM_SIZE, IPC_CREAT | 0600);
+    if (shmid == \-1)
+        errExit("shmget");
+\&
+    semid = semget(IPC_PRIVATE, 1, IPC_CREAT | 0600);
+    if (semid == \-1)
+        errExit("semget");
+\&
+    /* Attach shared memory into our address space. */
+\&
+    addr = shmat(shmid, NULL, SHM_RDONLY);
+    if (addr == (void *) \-1)
+        errExit("shmat");
+\&
+    /* Initialize semaphore 0 in set with value 1. */
+\&
+    arg.val = 1;
+    if (semctl(semid, 0, SETVAL, arg) == \-1)
+        errExit("semctl");
+\&
+    printf("shmid = %d; semid = %d\en", shmid, semid);
+\&
+    /* Wait for semaphore value to become 0. */
+\&
+    sop.sem_num = 0;
+    sop.sem_op = 0;
+    sop.sem_flg = 0;
+\&
+    if (semop(semid, &sop, 1) == \-1)
+        errExit("semop");
+\&
+    /* Print the string from shared memory. */
+\&
+    printf("%s\en", addr);
+\&
+    /* Remove shared memory and semaphore set. */
+\&
+    if (shmctl(shmid, IPC_RMID, NULL) == \-1)
+        errExit("shmctl");
+    if (semctl(semid, 0, IPC_RMID, dummy) == \-1)
+        errExit("semctl");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.\"
+.SS Program source: svshm_string_write.c
+The writer program takes three command-line arguments:
+the IDs of the shared memory segment and semaphore set
+that have already been created by the "reader", and a string.
+It attaches the shared memory segment into its address space,
+and then decrements the semaphore value to 0 in order to inform the
+"reader" that it can now examine the contents of the shared memory.
+.P
+.in +4n
+.\" SRC BEGIN (svshm_string_write.c)
+.EX
+/* svshm_string_write.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+\&
+#include "svshm_string.h"
+\&
+int
+main(int argc, char *argv[])
+{
+    int            semid, shmid;
+    char           *addr;
+    size_t         len;
+    struct sembuf  sop;
+\&
+    if (argc != 4) {
+        fprintf(stderr, "Usage: %s shmid semid string\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    len = strlen(argv[3]) + 1;  /* +1 to include trailing \[aq]\e0\[aq] */
+    if (len > MEM_SIZE) {
+        fprintf(stderr, "String is too big!\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Get object IDs from command\-line. */
+\&
+    shmid = atoi(argv[1]);
+    semid = atoi(argv[2]);
+\&
+    /* Attach shared memory into our address space and copy string
+       (including trailing null byte) into memory. */
+\&
+    addr = shmat(shmid, NULL, 0);
+    if (addr == (void *) \-1)
+        errExit("shmat");
+\&
+    memcpy(addr, argv[3], len);
+\&
+    /* Decrement semaphore to 0. */
+\&
+    sop.sem_num = 0;
+    sop.sem_op = \-1;
+    sop.sem_flg = 0;
+\&
+    if (semop(semid, &sop, 1) == \-1)
+        errExit("semop");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR brk (2),
+.BR mmap (2),
+.BR shmctl (2),
+.BR shmget (2),
+.BR capabilities (7),
+.BR shm_overview (7),
+.BR sysvipc (7)
diff --git a/man/man2/shutdown.2 b/man/man2/shutdown.2
new file mode 100644
index 000000000..d15566fb5
--- /dev/null
+++ b/man/man2/shutdown.2
@@ -0,0 +1,98 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     $Id: shutdown.2,v 1.1.1.1 1999/03/21 22:52:23 freitag Exp $
+.\"
+.\" Modified Sat Jul 24 09:57:55 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 22:04:51 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998 by Andi Kleen
+.\"
+.TH shutdown 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+shutdown \- shut down part of a full-duplex connection
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int shutdown(int " sockfd ", int " how );
+.fi
+.SH DESCRIPTION
+The
+.BR shutdown ()
+call causes all or part of a full-duplex connection on the socket
+associated with
+.I sockfd
+to be shut down.
+If
+.I how
+is
+.BR SHUT_RD ,
+further receptions will be disallowed.
+If
+.I how
+is
+.BR SHUT_WR ,
+further transmissions will be disallowed.
+If
+.I how
+is
+.BR SHUT_RDWR ,
+further receptions and transmissions will be disallowed.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+An invalid value was specified in
+.I how
+(but see BUGS).
+.TP
+.B ENOTCONN
+The specified socket is not connected.
+.TP
+.B ENOTSOCK
+The file descriptor
+.I sockfd
+does not refer to a socket.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.4BSD
+(first appeared in 4.2BSD).
+.SH NOTES
+The constants
+.BR SHUT_RD ,
+.BR SHUT_WR ,
+.B SHUT_RDWR
+have the value 0, 1, 2,
+respectively, and are defined in
+.I <sys/socket.h>
+since glibc-2.1.91.
+.SH BUGS
+Checks for the validity of
+.I how
+are done in domain-specific code,
+and before Linux 3.7 not all domains performed these checks.
+.\" https://bugzilla.kernel.org/show_bug.cgi?id=47111
+Most notably, UNIX domain sockets simply ignored invalid values.
+This problem was fixed for UNIX domain sockets
+.\" commit fc61b928dc4d72176cf4bd4d30bf1d22e599aefc
+.\" and for DECnet sockets in commit 46b66d7077b89fb4917ceef19b3f7dd86055c94a
+in Linux 3.7.
+.SH SEE ALSO
+.BR close (2),
+.BR connect (2),
+.BR socket (2),
+.BR socket (7)
diff --git a/man/man2/sigaction.2 b/man/man2/sigaction.2
new file mode 100644
index 000000000..daca34a27
--- /dev/null
+++ b/man/man2/sigaction.2
@@ -0,0 +1,1210 @@
+.\" Copyright (c) 1994,1995 Mike Battersby <mib@deakin.edu.au>
+.\" and Copyright 2004, 2005 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" based on work by faith@cs.unc.edu
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified, aeb, 960424
+.\" Modified Fri Jan 31 17:31:20 1997 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Thu Nov 26 02:12:45 1998 by aeb - add SIGCHLD stuff.
+.\" Modified Sat May  8 17:40:19 1999 by Matthew Wilcox
+.\"	add POSIX.1b signals
+.\" Modified Sat Dec 29 01:44:52 2001 by Evan Jones <ejones@uwaterloo.ca>
+.\"	SA_ONSTACK
+.\" Modified 2004-11-11 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added mention of SIGCONT under SA_NOCLDSTOP
+.\"	Added SA_NOCLDWAIT
+.\" Modified 2004-11-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Updated discussion for POSIX.1-2001 and SIGCHLD and sa_flags.
+.\"	Formatting fixes
+.\" 2004-12-09, mtk, added SI_TKILL + other minor changes
+.\" 2005-09-15, mtk, split sigpending(), sigprocmask(), sigsuspend()
+.\"	out of this page into separate pages.
+.\" 2010-06-11 Andi Kleen, add hwpoison signal extensions
+.\" 2010-06-11 mtk, improvements to discussion of various siginfo_t fields.
+.\" 2015-01-17, Kees Cook <keescook@chromium.org>
+.\"	Added notes on ptrace SIGTRAP and SYS_SECCOMP.
+.\"
+.TH sigaction 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigaction, rt_sigaction \- examine and change a signal action
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigaction(int " signum ,
+.BI "              const struct sigaction *_Nullable restrict " act ,
+.BI "              struct sigaction *_Nullable restrict " oldact );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigaction ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.P
+.IR siginfo_t :
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+The
+.BR sigaction ()
+system call is used to change the action taken by a process on
+receipt of a specific signal.
+(See
+.BR signal (7)
+for an overview of signals.)
+.P
+.I signum
+specifies the signal and can be any valid signal except
+.B SIGKILL
+and
+.BR SIGSTOP .
+.P
+If
+.I act
+is non-NULL, the new action for signal
+.I signum
+is installed from
+.IR act .
+If
+.I oldact
+is non-NULL, the previous action is saved in
+.IR oldact .
+.P
+The
+.I sigaction
+structure is defined as something like:
+.P
+.in +4n
+.EX
+struct sigaction {
+    void     (*sa_handler)(int);
+    void     (*sa_sigaction)(int, siginfo_t *, void *);
+    sigset_t   sa_mask;
+    int        sa_flags;
+    void     (*sa_restorer)(void);
+};
+.EE
+.in
+.P
+On some architectures a union is involved: do not assign to both
+.I sa_handler
+and
+.IR sa_sigaction .
+.P
+The
+.I sa_restorer
+field is not intended for application use.
+(POSIX does not specify a
+.I sa_restorer
+field.)
+Some further details of the purpose of this field can be found in
+.BR sigreturn (2).
+.P
+.I sa_handler
+specifies the action to be associated with
+.I signum
+and can be one of the following:
+.IP \[bu] 3
+.B SIG_DFL
+for the default action.
+.IP \[bu]
+.B SIG_IGN
+to ignore this signal.
+.IP \[bu]
+A pointer to a signal handling function.
+This function receives the signal number as its only argument.
+.P
+If
+.B SA_SIGINFO
+is specified in
+.IR sa_flags ,
+then
+.I sa_sigaction
+(instead of
+.IR sa_handler )
+specifies the signal-handling function for
+.IR signum .
+This function receives three arguments, as described below.
+.P
+.I sa_mask
+specifies a mask of signals which should be blocked
+(i.e., added to the signal mask of the thread in which
+the signal handler is invoked)
+during execution of the signal handler.
+In addition, the signal which triggered the handler
+will be blocked, unless the
+.B SA_NODEFER
+flag is used.
+.P
+.I sa_flags
+specifies a set of flags which modify the behavior of the signal.
+It is formed by the bitwise OR of zero or more of the following:
+.TP
+.B SA_NOCLDSTOP
+If
+.I signum
+is
+.BR SIGCHLD ,
+do not receive notification when child processes stop (i.e., when they
+receive one of
+.BR SIGSTOP ", " SIGTSTP ", " SIGTTIN ,
+or
+.BR SIGTTOU )
+or resume (i.e., they receive
+.BR SIGCONT )
+(see
+.BR wait (2)).
+This flag is meaningful only when establishing a handler for
+.BR SIGCHLD .
+.TP
+.BR SA_NOCLDWAIT " (since Linux 2.6)"
+.\" To be precise: Linux 2.5.60 -- MTK
+If
+.I signum
+is
+.BR SIGCHLD ,
+do not transform children into zombies when they terminate.
+See also
+.BR waitpid (2).
+This flag is meaningful only when establishing a handler for
+.BR SIGCHLD ,
+or when setting that signal's disposition to
+.BR SIG_DFL .
+.IP
+If the
+.B SA_NOCLDWAIT
+flag is set when establishing a handler for
+.BR SIGCHLD ,
+POSIX.1 leaves it unspecified whether a
+.B SIGCHLD
+signal is generated when a child process terminates.
+On Linux, a
+.B SIGCHLD
+signal is generated in this case;
+on some other implementations, it is not.
+.TP
+.B SA_NODEFER
+Do not add the signal to the thread's signal mask while the
+handler is executing, unless the signal is specified in
+.IR act.sa_mask .
+Consequently, a further instance of the signal may be delivered
+to the thread while it is executing the handler.
+This flag is meaningful only when establishing a signal handler.
+.IP
+.B SA_NOMASK
+is an obsolete, nonstandard synonym for this flag.
+.TP
+.B SA_ONSTACK
+Call the signal handler on an alternate signal stack provided by
+.BR sigaltstack (2).
+If an alternate stack is not available, the default stack will be used.
+This flag is meaningful only when establishing a signal handler.
+.TP
+.B SA_RESETHAND
+Restore the signal action to the default upon entry to the signal handler.
+This flag is meaningful only when establishing a signal handler.
+.IP
+.B SA_ONESHOT
+is an obsolete, nonstandard synonym for this flag.
+.TP
+.B SA_RESTART
+Provide behavior compatible with BSD signal semantics by making certain
+system calls restartable across signals.
+This flag is meaningful only when establishing a signal handler.
+See
+.BR signal (7)
+for a discussion of system call restarting.
+.TP
+.B SA_RESTORER
+.IR "Not intended for application use" .
+This flag is used by C libraries to indicate that the
+.I sa_restorer
+field contains the address of a "signal trampoline".
+See
+.BR sigreturn (2)
+for more details.
+.TP
+.BR SA_SIGINFO " (since Linux 2.2)"
+The signal handler takes three arguments, not one.
+In this case,
+.I sa_sigaction
+should be set instead of
+.IR sa_handler .
+This flag is meaningful only when establishing a signal handler.
+.\" (The
+.\" .I sa_sigaction
+.\" field was added in Linux 2.1.86.)
+.\"
+.TP
+.BR SA_UNSUPPORTED " (since Linux 5.11)"
+Used to dynamically probe for flag bit support.
+.IP
+If an attempt to register a handler succeeds with this flag set in
+.I act\->sa_flags
+alongside other flags that are potentially unsupported by the kernel,
+and an immediately subsequent
+.BR sigaction ()
+call specifying the same signal number and with a non-NULL
+.I oldact
+argument yields
+.B SA_UNSUPPORTED
+.I clear
+in
+.IR oldact\->sa_flags ,
+then
+.I oldact\->sa_flags
+may be used as a bitmask
+describing which of the potentially unsupported flags are,
+in fact, supported.
+See the section "Dynamically probing for flag bit support"
+below for more details.
+.TP
+.BR SA_EXPOSE_TAGBITS " (since Linux 5.11)"
+Normally, when delivering a signal,
+an architecture-specific set of tag bits are cleared from the
+.I si_addr
+field of
+.IR siginfo_t .
+If this flag is set,
+an architecture-specific subset of the tag bits will be preserved in
+.IR si_addr .
+.IP
+Programs that need to be compatible with Linux versions older than 5.11
+must use
+.B SA_UNSUPPORTED
+to probe for support.
+.SS The siginfo_t argument to a SA_SIGINFO handler
+When the
+.B SA_SIGINFO
+flag is specified in
+.IR act.sa_flags ,
+the signal handler address is passed via the
+.I act.sa_sigaction
+field.
+This handler takes three arguments, as follows:
+.P
+.in +4n
+.EX
+void
+handler(int sig, siginfo_t *info, void *ucontext)
+{
+    ...
+}
+.EE
+.in
+.P
+These three arguments are as follows
+.TP
+.I sig
+The number of the signal that caused invocation of the handler.
+.TP
+.I info
+A pointer to a
+.IR siginfo_t ,
+which is a structure containing further information about the signal,
+as described below.
+.TP
+.I ucontext
+This is a pointer to a
+.I ucontext_t
+structure, cast to \fIvoid\ *\fP.
+The structure pointed to by this field contains
+signal context information that was saved
+on the user-space stack by the kernel; for details, see
+.BR sigreturn (2).
+Further information about the
+.I ucontext_t
+structure can be found in
+.BR getcontext (3)
+and
+.BR signal (7).
+Commonly, the handler function doesn't make any use of the third argument.
+.P
+The
+.I siginfo_t
+data type is a structure with the following fields:
+.P
+.in +4n
+.EX
+siginfo_t {
+    int      si_signo;     /* Signal number */
+    int      si_errno;     /* An errno value */
+    int      si_code;      /* Signal code */
+    int      si_trapno;    /* Trap number that caused
+                              hardware\-generated signal
+                              (unused on most architectures) */
+.\" FIXME
+.\" The siginfo_t 'si_trapno' field seems to be used
+.\" only on SPARC and Alpha; this page could use
+.\" a little more detail on its purpose there.
+    pid_t    si_pid;       /* Sending process ID */
+    uid_t    si_uid;       /* Real user ID of sending process */
+    int      si_status;    /* Exit value or signal */
+    clock_t  si_utime;     /* User time consumed */
+    clock_t  si_stime;     /* System time consumed */
+    union sigval si_value; /* Signal value */
+    int      si_int;       /* POSIX.1b signal */
+    void    *si_ptr;       /* POSIX.1b signal */
+    int      si_overrun;   /* Timer overrun count;
+                              POSIX.1b timers */
+    int      si_timerid;   /* Timer ID; POSIX.1b timers */
+.\" In the kernel: si_tid
+    void    *si_addr;      /* Memory location which caused fault */
+    long     si_band;      /* Band event (was \fIint\fP in
+                              glibc 2.3.2 and earlier) */
+    int      si_fd;        /* File descriptor */
+    short    si_addr_lsb;  /* Least significant bit of address
+                              (since Linux 2.6.32) */
+    void    *si_lower;     /* Lower bound when address violation
+                              occurred (since Linux 3.19) */
+    void    *si_upper;     /* Upper bound when address violation
+                              occurred (since Linux 3.19) */
+    int      si_pkey;      /* Protection key on PTE that caused
+                              fault (since Linux 4.6) */
+    void    *si_call_addr; /* Address of system call instruction
+                              (since Linux 3.5) */
+    int      si_syscall;   /* Number of attempted system call
+                              (since Linux 3.5) */
+    unsigned int si_arch;  /* Architecture of attempted system call
+                              (since Linux 3.5) */
+}
+.EE
+.in
+.P
+.IR si_signo ", " si_errno " and " si_code
+are defined for all signals.
+.RI ( si_errno
+is generally unused on Linux.)
+The rest of the struct may be a union, so that one should
+read only the fields that are meaningful for the given signal:
+.IP \[bu] 3
+Signals sent with
+.BR kill (2)
+and
+.BR sigqueue (3)
+fill in
+.IR si_pid " and " si_uid .
+In addition, signals sent with
+.BR sigqueue (3)
+fill in
+.IR si_int " and " si_ptr
+with the values specified by the sender of the signal;
+see
+.BR sigqueue (3)
+for more details.
+.IP \[bu]
+Signals sent by POSIX.1b timers (since Linux 2.6) fill in
+.I si_overrun
+and
+.IR si_timerid .
+The
+.I si_timerid
+field is an internal ID used by the kernel to identify
+the timer; it is not the same as the timer ID returned by
+.BR timer_create (2).
+The
+.I si_overrun
+field is the timer overrun count;
+this is the same information as is obtained by a call to
+.BR timer_getoverrun (2).
+These fields are nonstandard Linux extensions.
+.IP \[bu]
+Signals sent for message queue notification (see the description of
+.B SIGEV_SIGNAL
+in
+.BR mq_notify (3))
+fill in
+.IR si_int / si_ptr ,
+with the
+.I sigev_value
+supplied to
+.BR mq_notify (3);
+.IR si_pid ,
+with the process ID of the message sender; and
+.IR si_uid ,
+with the real user ID of the message sender.
+.IP \[bu]
+.B SIGCHLD
+fills in
+.IR si_pid ", " si_uid ", " si_status ", " si_utime ", and " si_stime ,
+providing information about the child.
+The
+.I si_pid
+field is the process ID of the child;
+.I si_uid
+is the child's real user ID.
+The
+.I si_status
+field contains the exit status of the child (if
+.I si_code
+is
+.BR CLD_EXITED ),
+or the signal number that caused the process to change state.
+The
+.I si_utime
+and
+.I si_stime
+contain the user and system CPU time used by the child process;
+these fields do not include the times used by waited-for children (unlike
+.BR getrusage (2)
+and
+.BR times (2)).
+Up to Linux 2.6, and since Linux 2.6.27, these fields report
+CPU time in units of
+.IR sysconf(_SC_CLK_TCK) .
+In Linux 2.6 kernels before Linux 2.6.27,
+a bug meant that these fields reported time in units
+of the (configurable) system jiffy (see
+.BR time (7)).
+.\" FIXME .
+.\" When si_utime and si_stime where originally implemented, the
+.\" measurement unit was HZ, which was the same as clock ticks
+.\" (sysconf(_SC_CLK_TCK)).  In Linux 2.6, HZ became configurable, and
+.\" was *still* used as the unit to return the info these fields,
+.\" with the result that the field values depended on the
+.\" configured HZ.  Of course, the should have been measured in
+.\" USER_HZ instead, so that sysconf(_SC_CLK_TCK) could be used to
+.\" convert to seconds.  I have a queued patch to fix this:
+.\" http://thread.gmane.org/gmane.linux.kernel/698061/ .
+.\" This patch made it into Linux 2.6.27.
+.\" But note that these fields still don't return the times of
+.\" waited-for children (as is done by getrusage() and times()
+.\" and wait4()).  Solaris 8 does include child times.
+.IP \[bu]
+.BR SIGILL ,
+.BR SIGFPE ,
+.BR SIGSEGV ,
+.BR SIGBUS ,
+and
+.B SIGTRAP
+fill in
+.I si_addr
+with the address of the fault.
+On some architectures,
+these signals also fill in the
+.I si_trapno
+field.
+.IP
+Some suberrors of
+.BR SIGBUS ,
+in particular
+.B BUS_MCEERR_AO
+and
+.BR BUS_MCEERR_AR ,
+also fill in
+.IR si_addr_lsb .
+This field indicates the least significant bit of the reported address
+and therefore the extent of the corruption.
+For example, if a full page was corrupted,
+.I si_addr_lsb
+contains
+.IR log2(sysconf(_SC_PAGESIZE)) .
+When
+.B SIGTRAP
+is delivered in response to a
+.BR ptrace (2)
+event (PTRACE_EVENT_foo),
+.I si_addr
+is not populated, but
+.I si_pid
+and
+.I si_uid
+are populated with the respective process ID and user ID responsible for
+delivering the trap.
+In the case of
+.BR seccomp (2),
+the tracee will be shown as delivering the event.
+.B BUS_MCEERR_*
+and
+.I si_addr_lsb
+are Linux-specific extensions.
+.IP
+The
+.B SEGV_BNDERR
+suberror of
+.B SIGSEGV
+populates
+.I si_lower
+and
+.IR si_upper .
+.IP
+The
+.B SEGV_PKUERR
+suberror of
+.B SIGSEGV
+populates
+.IR si_pkey .
+.IP \[bu]
+.BR SIGIO / SIGPOLL
+(the two names are synonyms on Linux)
+fills in
+.I si_band
+and
+.IR si_fd .
+The
+.I si_band
+event is a bit mask containing the same values as are filled in the
+.I revents
+field by
+.BR poll (2).
+The
+.I si_fd
+field indicates the file descriptor for which the I/O event occurred;
+for further details, see the description of
+.B F_SETSIG
+in
+.BR fcntl (2).
+.IP \[bu]
+.BR SIGSYS ,
+generated (since Linux 3.5)
+.\" commit a0727e8ce513fe6890416da960181ceb10fbfae6
+when a seccomp filter returns
+.BR SECCOMP_RET_TRAP ,
+fills in
+.IR si_call_addr ,
+.IR si_syscall ,
+.IR si_arch ,
+.IR si_errno ,
+and other fields as described in
+.BR seccomp (2).
+.\"
+.SS
+The si_code field
+The
+.I si_code
+field inside the
+.I siginfo_t
+argument that is passed to a
+.B SA_SIGINFO
+signal handler is a value (not a bit mask)
+indicating why this signal was sent.
+For a
+.BR ptrace (2)
+event,
+.I si_code
+will contain
+.B SIGTRAP
+and have the ptrace event in the high byte:
+.P
+.in +4n
+.EX
+(SIGTRAP | PTRACE_EVENT_foo << 8).
+.EE
+.in
+.P
+For a
+.RB non- ptrace (2)
+event, the values that can appear in
+.I si_code
+are described in the remainder of this section.
+Since glibc 2.20,
+the definitions of most of these symbols are obtained from
+.I <signal.h>
+by defining feature test macros (before including
+.I any
+header file) as follows:
+.IP \[bu] 3
+.B _XOPEN_SOURCE
+with the value 500 or greater;
+.IP \[bu]
+.B _XOPEN_SOURCE
+and
+.BR _XOPEN_SOURCE_EXTENDED ;
+or
+.IP \[bu]
+.B _POSIX_C_SOURCE
+with the value 200809L or greater.
+.P
+For the
+.B TRAP_*
+constants, the symbol definitions are provided only in the first two cases.
+Before glibc 2.20, no feature test macros were required to obtain these symbols.
+.P
+For a regular signal, the following list shows the values which can be
+placed in
+.I si_code
+for any signal, along with the reason that the signal was generated.
+.RS 4
+.TP
+.B SI_USER
+.BR kill (2).
+.TP
+.B SI_KERNEL
+Sent by the kernel.
+.TP
+.B SI_QUEUE
+.BR sigqueue (3).
+.TP
+.B SI_TIMER
+POSIX timer expired.
+.TP
+.BR SI_MESGQ " (since Linux 2.6.6)"
+POSIX message queue state changed; see
+.BR mq_notify (3).
+.TP
+.B SI_ASYNCIO
+AIO completed.
+.TP
+.B SI_SIGIO
+Queued
+.B SIGIO
+(only up to Linux 2.2; from Linux 2.4 onward
+.BR SIGIO / SIGPOLL
+fills in
+.I si_code
+as described below).
+.TP
+.BR SI_TKILL " (since Linux 2.4.19)"
+.BR tkill (2)
+or
+.BR tgkill (2).
+.\" SI_DETHREAD is defined in Linux 2.6.9 sources, but isn't implemented
+.\" It appears to have been an idea that was tried during 2.5.6
+.\" through to Linux 2.5.24 and then was backed out.
+.RE
+.P
+The following values can be placed in
+.I si_code
+for a
+.B SIGILL
+signal:
+.RS 4
+.TP
+.B ILL_ILLOPC
+Illegal opcode.
+.TP
+.B ILL_ILLOPN
+Illegal operand.
+.TP
+.B ILL_ILLADR
+Illegal addressing mode.
+.TP
+.B ILL_ILLTRP
+Illegal trap.
+.TP
+.B ILL_PRVOPC
+Privileged opcode.
+.TP
+.B ILL_PRVREG
+Privileged register.
+.TP
+.B ILL_COPROC
+Coprocessor error.
+.TP
+.B ILL_BADSTK
+Internal stack error.
+.RE
+.P
+The following values can be placed in
+.I si_code
+for a
+.B SIGFPE
+signal:
+.RS 4
+.TP
+.B FPE_INTDIV
+Integer divide by zero.
+.TP
+.B FPE_INTOVF
+Integer overflow.
+.TP
+.B FPE_FLTDIV
+Floating-point divide by zero.
+.TP
+.B FPE_FLTOVF
+Floating-point overflow.
+.TP
+.B FPE_FLTUND
+Floating-point underflow.
+.TP
+.B FPE_FLTRES
+Floating-point inexact result.
+.TP
+.B FPE_FLTINV
+Floating-point invalid operation.
+.TP
+.B FPE_FLTSUB
+Subscript out of range.
+.RE
+.P
+The following values can be placed in
+.I si_code
+for a
+.B SIGSEGV
+signal:
+.RS 4
+.TP
+.B SEGV_MAPERR
+Address not mapped to object.
+.TP
+.B SEGV_ACCERR
+Invalid permissions for mapped object.
+.TP
+.BR SEGV_BNDERR " (since Linux 3.19)"
+.\" commit ee1b58d36aa1b5a79eaba11f5c3633c88231da83
+Failed address bound checks.
+.TP
+.BR SEGV_PKUERR " (since Linux 4.6)"
+.\" commit cd0ea35ff5511cde299a61c21a95889b4a71464e
+Access was denied by memory protection keys.
+See
+.BR pkeys (7).
+The protection key which applied to this access is available via
+.IR si_pkey .
+.RE
+.P
+The following values can be placed in
+.I si_code
+for a
+.B SIGBUS
+signal:
+.RS 4
+.TP
+.B BUS_ADRALN
+Invalid address alignment.
+.TP
+.B BUS_ADRERR
+Nonexistent physical address.
+.TP
+.B BUS_OBJERR
+Object-specific hardware error.
+.TP
+.BR BUS_MCEERR_AR " (since Linux 2.6.32)"
+Hardware memory error consumed on a machine check; action required.
+.TP
+.BR BUS_MCEERR_AO " (since Linux 2.6.32)"
+Hardware memory error detected in process but not consumed; action optional.
+.RE
+.P
+The following values can be placed in
+.I si_code
+for a
+.B SIGTRAP
+signal:
+.RS 4
+.TP
+.B TRAP_BRKPT
+Process breakpoint.
+.TP
+.B TRAP_TRACE
+Process trace trap.
+.TP
+.BR TRAP_BRANCH " (since Linux 2.4, IA64 only)"
+Process taken branch trap.
+.TP
+.BR TRAP_HWBKPT " (since Linux 2.4, IA64 only)"
+Hardware breakpoint/watchpoint.
+.RE
+.P
+The following values can be placed in
+.I si_code
+for a
+.B SIGCHLD
+signal:
+.RS 4
+.TP
+.B CLD_EXITED
+Child has exited.
+.TP
+.B CLD_KILLED
+Child was killed.
+.TP
+.B CLD_DUMPED
+Child terminated abnormally.
+.TP
+.B CLD_TRAPPED
+Traced child has trapped.
+.TP
+.B CLD_STOPPED
+Child has stopped.
+.TP
+.BR CLD_CONTINUED " (since Linux 2.6.9)"
+Stopped child has continued.
+.RE
+.P
+The following values can be placed in
+.I si_code
+for a
+.BR SIGIO / SIGPOLL
+signal:
+.RS 4
+.TP
+.B POLL_IN
+Data input available.
+.TP
+.B POLL_OUT
+Output buffers available.
+.TP
+.B POLL_MSG
+Input message available.
+.TP
+.B POLL_ERR
+I/O error.
+.TP
+.B POLL_PRI
+High priority input available.
+.TP
+.B POLL_HUP
+Device disconnected.
+.RE
+.P
+The following value can be placed in
+.I si_code
+for a
+.B SIGSYS
+signal:
+.RS 4
+.TP
+.BR SYS_SECCOMP " (since Linux 3.5)"
+Triggered by a
+.BR seccomp (2)
+filter rule.
+.RE
+.SS Dynamically probing for flag bit support
+The
+.BR sigaction ()
+call on Linux accepts unknown bits set in
+.I act\->sa_flags
+without error.
+The behavior of the kernel starting with Linux 5.11 is that a second
+.BR sigaction ()
+will clear unknown bits from
+.IR oldact\->sa_flags .
+However, historically, a second
+.BR sigaction ()
+call would typically leave those bits set in
+.IR oldact\->sa_flags .
+.P
+This means that support for new flags cannot be detected
+simply by testing for a flag in
+.IR sa_flags ,
+and a program must test that
+.B SA_UNSUPPORTED
+has been cleared before relying on the contents of
+.IR sa_flags .
+.P
+Since the behavior of the signal handler cannot be guaranteed
+unless the check passes,
+it is wise to either block the affected signal
+while registering the handler and performing the check in this case,
+or where this is not possible,
+for example if the signal is synchronous, to issue the second
+.BR sigaction ()
+in the signal handler itself.
+.P
+In kernels that do not support a specific flag,
+the kernel's behavior is as if the flag was not set,
+even if the flag was set in
+.IR act\->sa_flags .
+.P
+The flags
+.BR SA_NOCLDSTOP ,
+.BR SA_NOCLDWAIT ,
+.BR SA_SIGINFO ,
+.BR SA_ONSTACK ,
+.BR SA_RESTART ,
+.BR SA_NODEFER ,
+.BR SA_RESETHAND ,
+and, if defined by the architecture,
+.B SA_RESTORER
+may not be reliably probed for using this mechanism,
+because they were introduced before Linux 5.11.
+However, in general, programs may assume that these flags are supported,
+since they have all been supported since Linux 2.6,
+which was released in the year 2003.
+.P
+See EXAMPLES below for a demonstration of the use of
+.BR SA_UNSUPPORTED .
+.SH RETURN VALUE
+.BR sigaction ()
+returns 0 on success; on error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.IR act " or " oldact
+points to memory which is not a valid part of the process address space.
+.TP
+.B EINVAL
+An invalid signal was specified.
+This will also be generated if an attempt
+is made to change the action for
+.BR SIGKILL " or " SIGSTOP ,
+which cannot be caught or ignored.
+.SH VERSIONS
+.SS C library/kernel differences
+The glibc wrapper function for
+.BR sigaction ()
+gives an error
+.RB ( EINVAL )
+on attempts to change the disposition of the two real-time signals
+used internally by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.P
+On architectures where the signal trampoline resides in the C library,
+the glibc wrapper function for
+.BR sigaction ()
+places the address of the trampoline code in the
+.I act.sa_restorer
+field and sets the
+.B SA_RESTORER
+flag in the
+.I act.sa_flags
+field.
+See
+.BR sigreturn (2).
+.P
+The original Linux system call was named
+.BR sigaction ().
+However, with the addition of real-time signals in Linux 2.2,
+the fixed-size, 32-bit
+.I sigset_t
+type supported by that system call was no longer fit for purpose.
+Consequently, a new system call,
+.BR rt_sigaction (),
+was added to support an enlarged
+.I sigset_t
+type.
+The new system call takes a fourth argument,
+.IR "size_t sigsetsize" ,
+which specifies the size in bytes of the signal sets in
+.I act.sa_mask
+and
+.IR oldact.sa_mask .
+This argument is currently required to have the value
+.I sizeof(sigset_t)
+(or the error
+.B EINVAL
+results).
+The glibc
+.BR sigaction ()
+wrapper function hides these details from us, transparently calling
+.BR rt_sigaction ()
+when the kernel provides it.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.\" SVr4 does not document the EINTR condition.
+.P
+POSIX.1-1990 disallowed setting the action for
+.B SIGCHLD
+to
+.BR SIG_IGN .
+POSIX.1-2001 and later allow this possibility, so that ignoring
+.B SIGCHLD
+can be used to prevent the creation of zombies (see
+.BR wait (2)).
+Nevertheless, the historical BSD and System\ V behaviors for ignoring
+.B SIGCHLD
+differ, so that the only completely portable method of ensuring that
+terminated children do not become zombies is to catch the
+.B SIGCHLD
+signal and perform a
+.BR wait (2)
+or similar.
+.P
+POSIX.1-1990 specified only
+.BR SA_NOCLDSTOP .
+POSIX.1-2001 added
+.BR SA_NOCLDWAIT ,
+.BR SA_NODEFER ,
+.BR SA_ONSTACK ,
+.BR SA_RESETHAND ,
+.BR SA_RESTART ,
+and
+.B SA_SIGINFO
+as XSI extensions.
+POSIX.1-2008 moved
+.BR SA_NODEFER ,
+.BR SA_RESETHAND ,
+.BR SA_RESTART ,
+and
+.B SA_SIGINFO
+to the base specifications.
+Use of these latter values in
+.I sa_flags
+may be less portable in applications intended for older
+UNIX implementations.
+.P
+The
+.B SA_RESETHAND
+flag is compatible with the SVr4 flag of the same name.
+.P
+The
+.B SA_NODEFER
+flag is compatible with the SVr4 flag of the same name under kernels
+1.3.9 and later.
+On older kernels the Linux implementation
+allowed the receipt of any signal, not just the one we are installing
+(effectively overriding any
+.I sa_mask
+settings).
+.SH NOTES
+A child created via
+.BR fork (2)
+inherits a copy of its parent's signal dispositions.
+During an
+.BR execve (2),
+the dispositions of handled signals are reset to the default;
+the dispositions of ignored signals are left unchanged.
+.P
+According to POSIX, the behavior of a process is undefined after it
+ignores a
+.BR SIGFPE ,
+.BR SIGILL ,
+or
+.B SIGSEGV
+signal that was not generated by
+.BR kill (2)
+or
+.BR raise (3).
+Integer division by zero has undefined result.
+On some architectures it will generate a
+.B SIGFPE
+signal.
+(Also dividing the most negative integer by \-1 may generate
+.BR SIGFPE .)
+Ignoring this signal might lead to an endless loop.
+.P
+.BR sigaction ()
+can be called with a NULL second argument to query the current signal
+handler.
+It can also be used to check whether a given signal is valid for
+the current machine by calling it with NULL second and third arguments.
+.P
+It is not possible to block
+.BR SIGKILL " or " SIGSTOP
+(by specifying them in
+.IR sa_mask ).
+Attempts to do so are silently ignored.
+.P
+See
+.BR sigsetops (3)
+for details on manipulating signal sets.
+.P
+See
+.BR signal\-safety (7)
+for a list of the async-signal-safe functions that can be
+safely called inside from inside a signal handler.
+.\"
+.SS Undocumented
+Before the introduction of
+.BR SA_SIGINFO ,
+it was also possible to get some additional information about the signal.
+This was done by providing an
+.I sa_handler
+signal handler with a second argument of type
+.IR "struct sigcontext" ,
+which is the same structure as the one that is passed in the
+.I uc_mcontext
+field of the
+.I ucontext
+structure that is passed (via a pointer) in the third argument of the
+.I sa_sigaction
+handler.
+See the relevant Linux kernel sources for details.
+This use is obsolete now.
+.SH BUGS
+When delivering a signal with a
+.B SA_SIGINFO
+handler,
+the kernel does not always provide meaningful values
+for all of the fields of the
+.I siginfo_t
+that are relevant for that signal.
+.P
+Up to and including Linux 2.6.13, specifying
+.B SA_NODEFER
+in
+.I sa_flags
+prevents not only the delivered signal from being masked during
+execution of the handler, but also the signals specified in
+.IR sa_mask .
+This bug was fixed in Linux 2.6.14.
+.\" commit 69be8f189653cd81aae5a74e26615b12871bb72e
+.SH EXAMPLES
+See
+.BR mprotect (2).
+.SS Probing for flag support
+The following example program exits with status
+.B EXIT_SUCCESS
+if
+.B SA_EXPOSE_TAGBITS
+is determined to be supported, and
+.B EXIT_FAILURE
+otherwise.
+.P
+.\" SRC BEGIN (sigaction.c)
+.EX
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+void
+handler(int signo, siginfo_t *info, void *context)
+{
+    struct sigaction oldact;
+\&
+    if (sigaction(SIGSEGV, NULL, &oldact) == \-1
+        || (oldact.sa_flags & SA_UNSUPPORTED)
+        || !(oldact.sa_flags & SA_EXPOSE_TAGBITS))
+    {
+        _exit(EXIT_FAILURE);
+    }
+    _exit(EXIT_SUCCESS);
+}
+\&
+int
+main(void)
+{
+    struct sigaction act = { 0 };
+\&
+    act.sa_flags = SA_SIGINFO | SA_UNSUPPORTED | SA_EXPOSE_TAGBITS;
+    act.sa_sigaction = &handler;
+    if (sigaction(SIGSEGV, &act, NULL) == \-1) {
+        perror("sigaction");
+        exit(EXIT_FAILURE);
+    }
+\&
+    raise(SIGSEGV);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR kill (1),
+.BR kill (2),
+.BR pause (2),
+.BR pidfd_send_signal (2),
+.BR restart_syscall (2),
+.BR seccomp (2),
+.BR sigaltstack (2),
+.BR signal (2),
+.BR signalfd (2),
+.BR sigpending (2),
+.BR sigprocmask (2),
+.BR sigreturn (2),
+.BR sigsuspend (2),
+.BR wait (2),
+.BR killpg (3),
+.BR raise (3),
+.BR siginterrupt (3),
+.BR sigqueue (3),
+.BR sigsetops (3),
+.BR sigvec (3),
+.BR core (5),
+.BR signal (7)
diff --git a/man/man2/sigaltstack.2 b/man/man2/sigaltstack.2
new file mode 100644
index 000000000..bd5e6ab86
--- /dev/null
+++ b/man/man2/sigaltstack.2
@@ -0,0 +1,362 @@
+'\" t
+.\" Copyright (c) 2001, 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" aeb, various minor fixes
+.TH sigaltstack 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigaltstack \- set and/or get signal stack context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigaltstack(const stack_t *_Nullable restrict " ss ,
+.BI "                stack_t *_Nullable restrict " old_ss );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigaltstack ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR sigaltstack ()
+allows a thread to define a new alternate
+signal stack and/or retrieve the state of an existing
+alternate signal stack.
+An alternate signal stack is used during the
+execution of a signal handler if the establishment of that handler (see
+.BR sigaction (2))
+requested it.
+.P
+The normal sequence of events for using an alternate signal stack
+is the following:
+.TP 3
+1.
+Allocate an area of memory to be used for the alternate
+signal stack.
+.TP
+2.
+Use
+.BR sigaltstack ()
+to inform the system of the existence and
+location of the alternate signal stack.
+.TP
+3.
+When establishing a signal handler using
+.BR sigaction (2),
+inform the system that the signal handler should be executed
+on the alternate signal stack by
+specifying the \fBSA_ONSTACK\fP flag.
+.P
+The \fIss\fP argument is used to specify a new
+alternate signal stack, while the \fIold_ss\fP argument
+is used to retrieve information about the currently
+established signal stack.
+If we are interested in performing just one
+of these tasks, then the other argument can be specified as NULL.
+.P
+The
+.I stack_t
+type used to type the arguments of this function is defined as follows:
+.P
+.in +4n
+.EX
+typedef struct {
+    void  *ss_sp;     /* Base address of stack */
+    int    ss_flags;  /* Flags */
+    size_t ss_size;   /* Number of bytes in stack */
+} stack_t;
+.EE
+.in
+.P
+To establish a new alternate signal stack,
+the fields of this structure are set as follows:
+.TP
+.I ss.ss_flags
+This field contains either 0, or the following flag:
+.RS
+.TP
+.BR SS_AUTODISARM " (since Linux 4.7)"
+.\" commit 2a74213838104a41588d86fd5e8d344972891ace
+.\" See tools/testing/selftests/sigaltstack/sas.c in kernel sources
+Clear the alternate signal stack settings on entry to the signal handler.
+When the signal handler returns,
+the previous alternate signal stack settings are restored.
+.IP
+This flag was added in order to make it safe
+to switch away from the signal handler with
+.BR swapcontext (3).
+Without this flag, a subsequently handled signal will corrupt
+the state of the switched-away signal handler.
+On kernels where this flag is not supported,
+.BR sigaltstack ()
+fails with the error
+.B EINVAL
+when this flag is supplied.
+.RE
+.TP
+.I ss.ss_sp
+This field specifies the starting address of the stack.
+When a signal handler is invoked on the alternate stack,
+the kernel automatically aligns the address given in \fIss.ss_sp\fP
+to a suitable address boundary for the underlying hardware architecture.
+.TP
+.I ss.ss_size
+This field specifies the size of the stack.
+The constant \fBSIGSTKSZ\fP is defined to be large enough
+to cover the usual size requirements for an alternate signal stack,
+and the constant \fBMINSIGSTKSZ\fP defines the minimum
+size required to execute a signal handler.
+.P
+To disable an existing stack, specify \fIss.ss_flags\fP
+as \fBSS_DISABLE\fP.
+In this case, the kernel ignores any other flags in
+.I ss.ss_flags
+and the remaining fields
+in \fIss\fP.
+.P
+If \fIold_ss\fP is not NULL, then it is used to return information about
+the alternate signal stack which was in effect prior to the
+call to
+.BR sigaltstack ().
+The \fIold_ss.ss_sp\fP and \fIold_ss.ss_size\fP fields return the starting
+address and size of that stack.
+The \fIold_ss.ss_flags\fP may return either of the following values:
+.TP
+.B SS_ONSTACK
+The thread is currently executing on the alternate signal stack.
+(Note that it is not possible
+to change the alternate signal stack if the thread is
+currently executing on it.)
+.TP
+.B SS_DISABLE
+The alternate signal stack is currently disabled.
+.IP
+Alternatively, this value is returned if the thread is currently
+executing on an alternate signal stack that was established using the
+.B SS_AUTODISARM
+flag.
+In this case, it is safe to switch away from the signal handler with
+.BR swapcontext (3).
+It is also possible to set up a different alternative signal stack
+using a further call to
+.BR sigaltstack ().
+.\" FIXME Was it intended that one can set up a different alternative
+.\" signal stack in this scenario? (In passing, if one does this, the
+.\" sigaltstack(NULL, &old_ss) now returns old_ss.ss_flags==SS_AUTODISARM
+.\" rather than old_ss.ss_flags==SS_DISABLE. The API design here seems
+.\" confusing...
+.TP
+.B SS_AUTODISARM
+The alternate signal stack has been marked to be autodisarmed
+as described above.
+.P
+By specifying
+.I ss
+as NULL, and
+.I old_ss
+as a non-NULL value, one can obtain the current settings for
+the alternate signal stack without changing them.
+.SH RETURN VALUE
+.BR sigaltstack ()
+returns 0 on success, or \-1 on failure with
+\fIerrno\fP set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Either \fIss\fP or \fIold_ss\fP is not NULL and points to an area
+outside of the process's address space.
+.TP
+.B EINVAL
+\fIss\fP is not NULL and the \fIss_flags\fP field contains
+an invalid flag.
+.TP
+.B ENOMEM
+The specified size of the new alternate signal stack
+.I ss.ss_size
+was less than
+.BR MINSIGSTKSZ .
+.TP
+.B EPERM
+An attempt was made to change the alternate signal stack while
+it was active (i.e., the thread was already executing
+on the current alternate signal stack).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sigaltstack ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.P
+.B SS_AUTODISARM
+is a Linux extension.
+.SH HISTORY
+POSIX.1-2001, SUSv2, SVr4.
+.SH NOTES
+The most common usage of an alternate signal stack is to handle the
+.B SIGSEGV
+signal that is generated if the space available for the
+standard stack is exhausted: in this case, a signal handler for
+.B SIGSEGV
+cannot be invoked on the standard stack; if we wish to handle it,
+we must use an alternate signal stack.
+.P
+Establishing an alternate signal stack is useful if a thread
+expects that it may exhaust its standard stack.
+This may occur, for example, because the stack grows so large
+that it encounters the upwardly growing heap, or it reaches a
+limit established by a call to \fB\%setrlimit(RLIMIT_STACK, &rlim)\fP.
+If the standard stack is exhausted, the kernel sends
+the thread a \fBSIGSEGV\fP signal.
+In these circumstances the only way to catch this signal is
+on an alternate signal stack.
+.P
+On most hardware architectures supported by Linux, stacks grow
+downward.
+.BR sigaltstack ()
+automatically takes account
+of the direction of stack growth.
+.P
+Functions called from a signal handler executing on an alternate
+signal stack will also use the alternate signal stack.
+(This also applies to any handlers invoked for other signals while
+the thread is executing on the alternate signal stack.)
+Unlike the standard stack, the system does not
+automatically extend the alternate signal stack.
+Exceeding the allocated size of the alternate signal stack will
+lead to unpredictable results.
+.P
+A successful call to
+.BR execve (2)
+removes any existing alternate
+signal stack.
+A child process created via
+.BR fork (2)
+inherits a copy of its parent's alternate signal stack settings.
+The same is also true for a child process created using
+.BR clone (2),
+unless the clone flags include
+.B CLONE_VM
+and do not include
+.BR CLONE_VFORK ,
+in which case any alternate signal stack that was established in the parent
+is disabled in the child process.
+.P
+.BR sigaltstack ()
+supersedes the older
+.BR sigstack ()
+call.
+For backward compatibility, glibc also provides
+.BR sigstack ().
+All new applications should be written using
+.BR sigaltstack ().
+.SS History
+4.2BSD had a
+.BR sigstack ()
+system call.
+It used a slightly
+different struct, and had the major disadvantage that the caller
+had to know the direction of stack growth.
+.SH BUGS
+In Linux 2.2 and earlier, the only flag that could be specified
+in
+.I ss.sa_flags
+was
+.BR SS_DISABLE .
+In the lead up to the release of the Linux 2.4 kernel,
+.\" Linux 2.3.40
+.\" After quite a bit of web and mail archive searching,
+.\" I could not find the patch on any mailing list, and I
+.\" could find no place where the rationale for this change
+.\" explained -- mtk
+a change was made to allow
+.BR sigaltstack ()
+to allow
+.I ss.ss_flags==SS_ONSTACK
+with the same meaning as
+.I ss.ss_flags==0
+(i.e., the inclusion of
+.B SS_ONSTACK
+in
+.I ss.ss_flags
+is a no-op).
+On other implementations, and according to POSIX.1,
+.B SS_ONSTACK
+appears only as a reported flag in
+.IR old_ss.ss_flags .
+On Linux, there is no need ever to specify
+.B SS_ONSTACK
+in
+.IR ss.ss_flags ,
+and indeed doing so should be avoided on portability grounds:
+various other systems
+.\" See the source code of Illumos and FreeBSD, for example.
+give an error if
+.B SS_ONSTACK
+is specified in
+.IR ss.ss_flags .
+.SH EXAMPLES
+The following code segment demonstrates the use of
+.BR sigaltstack ()
+(and
+.BR sigaction (2))
+to install an alternate signal stack that is employed by a handler
+for the
+.B SIGSEGV
+signal:
+.P
+.in +4n
+.EX
+stack_t ss;
+\&
+ss.ss_sp = malloc(SIGSTKSZ);
+if (ss.ss_sp == NULL) {
+    perror("malloc");
+    exit(EXIT_FAILURE);
+}
+\&
+ss.ss_size = SIGSTKSZ;
+ss.ss_flags = 0;
+if (sigaltstack(&ss, NULL) == \-1) {
+    perror("sigaltstack");
+    exit(EXIT_FAILURE);
+}
+\&
+sa.sa_flags = SA_ONSTACK;
+sa.sa_handler = handler();      /* Address of a signal handler */
+sigemptyset(&sa.sa_mask);
+if (sigaction(SIGSEGV, &sa, NULL) == \-1) {
+    perror("sigaction");
+    exit(EXIT_FAILURE);
+}
+.EE
+.in
+.SH SEE ALSO
+.BR execve (2),
+.BR setrlimit (2),
+.BR sigaction (2),
+.BR siglongjmp (3),
+.BR sigsetjmp (3),
+.BR signal (7)
diff --git a/man/man2/signal.2 b/man/man2/signal.2
new file mode 100644
index 000000000..5e84f40c3
--- /dev/null
+++ b/man/man2/signal.2
@@ -0,0 +1,280 @@
+.\" Copyright (c) 2000 Andries Brouwer <aeb@cwi.nl>
+.\" and Copyright (c) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"      <mtk.manpages@gmail.com>
+.\" based on work by Rik Faith <faith@cs.unc.edu>
+.\" and Mike Battersby <mike@starbug.apana.org.au>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 2004-11-19, mtk:
+.\" added pointer to sigaction.2 for details of ignoring SIGCHLD
+.\" 2007-06-03, mtk: strengthened portability warning, and rewrote
+.\"     various sections.
+.\" 2008-07-11, mtk: rewrote and expanded portability discussion.
+.\"
+.TH signal 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+signal \- ANSI C signal handling
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.B typedef void (*sighandler_t)(int);
+.P
+.BI "sighandler_t signal(int " signum ", sighandler_t " handler );
+.fi
+.SH DESCRIPTION
+.BR WARNING :
+the behavior of
+.BR signal ()
+varies across UNIX versions,
+and has also varied historically across different versions of Linux.
+\fBAvoid its use\fP: use
+.BR sigaction (2)
+instead.
+See \fIPortability\fP below.
+.P
+.BR signal ()
+sets the disposition of the signal
+.I signum
+to
+.IR handler ,
+which is either
+.BR SIG_IGN ,
+.BR SIG_DFL ,
+or the address of a programmer-defined function (a "signal handler").
+.P
+If the signal
+.I signum
+is delivered to the process, then one of the following happens:
+.TP 3
+*
+If the disposition is set to
+.BR SIG_IGN ,
+then the signal is ignored.
+.TP
+*
+If the disposition is set to
+.BR SIG_DFL ,
+then the default action associated with the signal (see
+.BR signal (7))
+occurs.
+.TP
+*
+If the disposition is set to a function,
+then first either the disposition is reset to
+.BR SIG_DFL ,
+or the signal is blocked (see \fIPortability\fP below), and then
+.I handler
+is called with argument
+.IR signum .
+If invocation of the handler caused the signal to be blocked,
+then the signal is unblocked upon return from the handler.
+.P
+The signals
+.B SIGKILL
+and
+.B SIGSTOP
+cannot be caught or ignored.
+.SH RETURN VALUE
+.BR signal ()
+returns the previous value of the signal handler.
+On failure, it returns
+.BR SIG_ERR ,
+and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I signum
+is invalid.
+.SH VERSIONS
+The use of
+.I sighandler_t
+is a GNU extension, exposed if
+.B _GNU_SOURCE
+is defined;
+.\" libc4 and libc5 define
+.\" .IR SignalHandler ;
+glibc also defines (the BSD-derived)
+.I sig_t
+if
+.B _BSD_SOURCE
+(glibc 2.19 and earlier)
+or
+.B _DEFAULT_SOURCE
+(glibc 2.19 and later)
+is defined.
+Without use of such a type, the declaration of
+.BR signal ()
+is the somewhat harder to read:
+.P
+.in +4n
+.EX
+.BI "void ( *" signal "(int " signum ", void (*" handler ")(int)) ) (int);"
+.EE
+.in
+.SS Portability
+The only portable use of
+.BR signal ()
+is to set a signal's disposition to
+.B SIG_DFL
+or
+.BR SIG_IGN .
+The semantics when using
+.BR signal ()
+to establish a signal handler vary across systems
+(and POSIX.1 explicitly permits this variation);
+.B do not use it for this purpose.
+.P
+POSIX.1 solved the portability mess by specifying
+.BR sigaction (2),
+which provides explicit control of the semantics when a
+signal handler is invoked; use that interface instead of
+.BR signal ().
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.P
+In the original UNIX systems, when a handler that was established using
+.BR signal ()
+was invoked by the delivery of a signal,
+the disposition of the signal would be reset to
+.BR SIG_DFL ,
+and the system did not block delivery of further instances of the signal.
+This is equivalent to calling
+.BR sigaction (2)
+with the following flags:
+.P
+.in +4n
+.EX
+sa.sa_flags = SA_RESETHAND | SA_NODEFER;
+.EE
+.in
+.P
+System\ V also provides these semantics for
+.BR signal ().
+This was bad because the signal might be delivered again
+before the handler had a chance to reestablish itself.
+Furthermore, rapid deliveries of the same signal could
+result in recursive invocations of the handler.
+.P
+BSD improved on this situation, but unfortunately also
+changed the semantics of the existing
+.BR signal ()
+interface while doing so.
+On BSD, when a signal handler is invoked,
+the signal disposition is not reset,
+and further instances of the signal are blocked from
+being delivered while the handler is executing.
+Furthermore, certain blocking system calls are automatically
+restarted if interrupted by a signal handler (see
+.BR signal (7)).
+The BSD semantics are equivalent to calling
+.BR sigaction (2)
+with the following flags:
+.P
+.in +4n
+.EX
+sa.sa_flags = SA_RESTART;
+.EE
+.in
+.P
+The situation on Linux is as follows:
+.IP \[bu] 3
+The kernel's
+.BR signal ()
+system call provides System\ V semantics.
+.IP \[bu]
+By default, in glibc 2 and later, the
+.BR signal ()
+wrapper function does not invoke the kernel system call.
+Instead, it calls
+.BR sigaction (2)
+using flags that supply BSD semantics.
+This default behavior is provided as long as a suitable
+feature test macro is defined:
+.B _BSD_SOURCE
+on glibc 2.19 and earlier or
+.B _DEFAULT_SOURCE
+in glibc 2.19 and later.
+(By default, these macros are defined; see
+.BR feature_test_macros (7)
+for details.)
+If such a feature test macro is not defined, then
+.BR signal ()
+provides System\ V semantics.
+.\"
+.\" System V semantics are also provided if one uses the separate
+.\" .BR sysv_signal (3)
+.\" function.
+.\" .IP \[bu]
+.\" The
+.\" .BR signal ()
+.\" function in Linux libc4 and libc5 provide System\ V semantics.
+.\" If one on a libc5 system includes
+.\" .I <bsd/signal.h>
+.\" instead of
+.\" .IR <signal.h> ,
+.\" then
+.\" .BR signal ()
+.\" provides BSD semantics.
+.SH NOTES
+The effects of
+.BR signal ()
+in a multithreaded process are unspecified.
+.P
+According to POSIX, the behavior of a process is undefined after it
+ignores a
+.BR SIGFPE ,
+.BR SIGILL ,
+or
+.B SIGSEGV
+signal that was not generated by
+.BR kill (2)
+or
+.BR raise (3).
+Integer division by zero has undefined result.
+On some architectures it will generate a
+.B SIGFPE
+signal.
+(Also dividing the most negative integer by \-1 may generate
+.BR SIGFPE .)
+Ignoring this signal might lead to an endless loop.
+.P
+See
+.BR sigaction (2)
+for details on what happens when the disposition
+.B SIGCHLD
+is set to
+.BR SIG_IGN .
+.P
+See
+.BR signal\-safety (7)
+for a list of the async-signal-safe functions that can be
+safely called from inside a signal handler.
+.SH SEE ALSO
+.BR kill (1),
+.BR alarm (2),
+.BR kill (2),
+.BR pause (2),
+.BR sigaction (2),
+.BR signalfd (2),
+.BR sigpending (2),
+.BR sigprocmask (2),
+.BR sigsuspend (2),
+.BR bsd_signal (3),
+.BR killpg (3),
+.BR raise (3),
+.BR siginterrupt (3),
+.BR sigqueue (3),
+.BR sigsetops (3),
+.BR sigvec (3),
+.BR sysv_signal (3),
+.BR signal (7)
diff --git a/man/man2/signalfd.2 b/man/man2/signalfd.2
new file mode 100644
index 000000000..831fa944c
--- /dev/null
+++ b/man/man2/signalfd.2
@@ -0,0 +1,525 @@
+.\" Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" starting from a version by Davide Libenzi <davidel@xmailserver.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH signalfd 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+signalfd \- create a file descriptor for accepting signals
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/signalfd.h>
+.P
+.BI "int signalfd(int " fd ", const sigset_t *" mask ", int " flags );
+.fi
+.SH DESCRIPTION
+.BR signalfd ()
+creates a file descriptor that can be used to accept signals
+targeted at the caller.
+This provides an alternative to the use of a signal handler or
+.BR sigwaitinfo (2),
+and has the advantage that the file descriptor may be monitored by
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7).
+.P
+The
+.I mask
+argument specifies the set of signals that the caller
+wishes to accept via the file descriptor.
+This argument is a signal set whose contents can be initialized
+using the macros described in
+.BR sigsetops (3).
+Normally, the set of signals to be received via the
+file descriptor should be blocked using
+.BR sigprocmask (2),
+to prevent the signals being handled according to their default
+dispositions.
+It is not possible to receive
+.B SIGKILL
+or
+.B SIGSTOP
+signals via a signalfd file descriptor;
+these signals are silently ignored if specified in
+.IR mask .
+.P
+If the
+.I fd
+argument is \-1,
+then the call creates a new file descriptor and associates the
+signal set specified in
+.I mask
+with that file descriptor.
+If
+.I fd
+is not \-1,
+then it must specify a valid existing signalfd file descriptor, and
+.I mask
+is used to replace the signal set associated with that file descriptor.
+.P
+Starting with Linux 2.6.27, the following values may be bitwise ORed in
+.I flags
+to change the behavior of
+.BR signalfd ():
+.TP 14
+.B SFD_NONBLOCK
+Set the
+.B O_NONBLOCK
+file status flag on the open file description (see
+.BR open (2))
+referred to by the new file descriptor.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
+.TP
+.B SFD_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.P
+Up to Linux 2.6.26, the
+.I flags
+argument is unused, and must be specified as zero.
+.P
+.BR signalfd ()
+returns a file descriptor that supports the following operations:
+.TP
+.BR read (2)
+If one or more of the signals specified in
+.I mask
+is pending for the process, then the buffer supplied to
+.BR read (2)
+is used to return one or more
+.I signalfd_siginfo
+structures (see below) that describe the signals.
+The
+.BR read (2)
+returns information for as many signals as are pending and will
+fit in the supplied buffer.
+The buffer must be at least
+.I "sizeof(struct signalfd_siginfo)"
+bytes.
+The return value of the
+.BR read (2)
+is the total number of bytes read.
+.IP
+As a consequence of the
+.BR read (2),
+the signals are consumed,
+so that they are no longer pending for the process
+(i.e., will not be caught by signal handlers,
+and cannot be accepted using
+.BR sigwaitinfo (2)).
+.IP
+If none of the signals in
+.I mask
+is pending for the process, then the
+.BR read (2)
+either blocks until one of the signals in
+.I mask
+is generated for the process,
+or fails with the error
+.B EAGAIN
+if the file descriptor has been made nonblocking.
+.TP
+.BR poll (2)
+.TQ
+.BR select (2)
+.TQ
+(and similar)
+The file descriptor is readable
+(the
+.BR select (2)
+.I readfds
+argument; the
+.BR poll (2)
+.B POLLIN
+flag)
+if one or more of the signals in
+.I mask
+is pending for the process.
+.IP
+The signalfd file descriptor also supports the other file-descriptor
+multiplexing APIs:
+.BR pselect (2),
+.BR ppoll (2),
+and
+.BR epoll (7).
+.TP
+.BR close (2)
+When the file descriptor is no longer required it should be closed.
+When all file descriptors associated with the same signalfd object
+have been closed, the resources for object are freed by the kernel.
+.SS The signalfd_siginfo structure
+The format of the
+.I signalfd_siginfo
+structure(s) returned by
+.BR read (2)s
+from a signalfd file descriptor is as follows:
+.P
+.in +4n
+.EX
+struct signalfd_siginfo {
+    uint32_t ssi_signo;    /* Signal number */
+    int32_t  ssi_errno;    /* Error number (unused) */
+    int32_t  ssi_code;     /* Signal code */
+    uint32_t ssi_pid;      /* PID of sender */
+    uint32_t ssi_uid;      /* Real UID of sender */
+    int32_t  ssi_fd;       /* File descriptor (SIGIO) */
+    uint32_t ssi_tid;      /* Kernel timer ID (POSIX timers)
+    uint32_t ssi_band;     /* Band event (SIGIO) */
+    uint32_t ssi_overrun;  /* POSIX timer overrun count */
+    uint32_t ssi_trapno;   /* Trap number that caused signal */
+.\" ssi_trapno is unused on most arches
+    int32_t  ssi_status;   /* Exit status or signal (SIGCHLD) */
+    int32_t  ssi_int;      /* Integer sent by sigqueue(3) */
+    uint64_t ssi_ptr;      /* Pointer sent by sigqueue(3) */
+    uint64_t ssi_utime;    /* User CPU time consumed (SIGCHLD) */
+    uint64_t ssi_stime;    /* System CPU time consumed
+                              (SIGCHLD) */
+    uint64_t ssi_addr;     /* Address that generated signal
+                              (for hardware\-generated signals) */
+    uint16_t ssi_addr_lsb; /* Least significant bit of address
+                              (SIGBUS; since Linux 2.6.37) */
+.\" ssi_addr_lsb: commit b8aeec34175fc8fe8b0d40efea4846dfc1ba663e
+    uint8_t  pad[\fIX\fP];       /* Pad size to 128 bytes (allow for
+                              additional fields in the future) */
+};
+.EE
+.in
+.P
+Each of the fields in this structure
+is analogous to the similarly named field in the
+.I siginfo_t
+structure.
+The
+.I siginfo_t
+structure is described in
+.BR sigaction (2).
+Not all fields in the returned
+.I signalfd_siginfo
+structure will be valid for a specific signal;
+the set of valid fields can be determined from the value returned in the
+.I ssi_code
+field.
+This field is the analog of the
+.I siginfo_t
+.I si_code
+field; see
+.BR sigaction (2)
+for details.
+.SS fork(2) semantics
+After a
+.BR fork (2),
+the child inherits a copy of the signalfd file descriptor.
+A
+.BR read (2)
+from the file descriptor in the child will return information
+about signals queued to the child.
+.SS Semantics of file descriptor passing
+As with other file descriptors,
+signalfd file descriptors can be passed to another process
+via a UNIX domain socket (see
+.BR unix (7)).
+In the receiving process, a
+.BR read (2)
+from the received file descriptor will return information
+about signals queued to that process.
+.SS execve(2) semantics
+Just like any other file descriptor,
+a signalfd file descriptor remains open across an
+.BR execve (2),
+unless it has been marked for close-on-exec (see
+.BR fcntl (2)).
+Any signals that were available for reading before the
+.BR execve (2)
+remain available to the newly loaded program.
+(This is analogous to traditional signal semantics,
+where a blocked signal that is pending remains pending across an
+.BR execve (2).)
+.SS Thread semantics
+The semantics of signalfd file descriptors in a multithreaded program
+mirror the standard semantics for signals.
+In other words,
+when a thread reads from a signalfd file descriptor,
+it will read the signals that are directed to the thread
+itself and the signals that are directed to the process
+(i.e., the entire thread group).
+(A thread will not be able to read signals that are directed
+to other threads in the process.)
+.\"
+.SS epoll(7) semantics
+If a process adds (via
+.BR epoll_ctl (2))
+a signalfd file descriptor to an
+.BR epoll (7)
+instance, then
+.BR epoll_wait (2)
+returns events only for signals sent to that process.
+In particular, if the process then uses
+.BR fork (2)
+to create a child process, then the child will be able to
+.BR read (2)
+signals that are sent to it using the signalfd file descriptor, but
+.BR epoll_wait (2)
+will
+.B not
+indicate that the signalfd file descriptor is ready.
+In this scenario, a possible workaround is that after the
+.BR fork (2),
+the child process can close the signalfd file descriptor that it inherited
+from the parent process and then create another signalfd file descriptor
+and add it to the epoll instance.
+Alternatively, the parent and the child could delay creating their
+(separate) signalfd file descriptors and adding them to the
+epoll instance until after the call to
+.BR fork (2).
+.SH RETURN VALUE
+On success,
+.BR signalfd ()
+returns a signalfd file descriptor;
+this is either a new file descriptor (if
+.I fd
+was \-1), or
+.I fd
+if
+.I fd
+was a valid signalfd file descriptor.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The
+.I fd
+file descriptor is not a valid file descriptor.
+.TP
+.B EINVAL
+.I fd
+is not a valid signalfd file descriptor.
+.\" or, the
+.\" .I sizemask
+.\" argument is not equal to
+.\" .IR sizeof(sigset_t) ;
+.TP
+.B EINVAL
+.I flags
+is invalid;
+or, in Linux 2.6.26 or earlier,
+.I flags
+is nonzero.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been
+reached.
+.TP
+.B ENODEV
+Could not mount (internal) anonymous inode device.
+.TP
+.B ENOMEM
+There was insufficient memory to create a new signalfd file descriptor.
+.SH VERSIONS
+.SS C library/kernel differences
+The underlying Linux system call requires an additional argument,
+.IR "size_t sizemask" ,
+which specifies the size of the
+.I mask
+argument.
+The glibc
+.BR signalfd ()
+wrapper function does not include this argument,
+since it provides the required value for the underlying system call.
+.P
+There are two underlying Linux system calls:
+.BR signalfd ()
+and the more recent
+.BR signalfd4 ().
+The former system call does not implement a
+.I flags
+argument.
+The latter system call implements the
+.I flags
+values described above.
+Starting with glibc 2.9, the
+.BR signalfd ()
+wrapper function will use
+.BR signalfd4 ()
+where it is available.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR signalfd ()
+Linux 2.6.22,
+glibc 2.8.
+.\" signalfd() is in glibc 2.7, but reportedly does not build
+.TP
+.BR signalfd4 ()
+Linux 2.6.27.
+.SH NOTES
+A process can create multiple signalfd file descriptors.
+This makes it possible to accept different signals
+on different file descriptors.
+(This may be useful if monitoring the file descriptors using
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7):
+the arrival of different signals will make different file descriptors ready.)
+If a signal appears in the
+.I mask
+of more than one of the file descriptors, then occurrences
+of that signal can be read (once) from any one of the file descriptors.
+.P
+Attempts to include
+.B SIGKILL
+and
+.B SIGSTOP
+in
+.I mask
+are silently ignored.
+.P
+The signal mask employed by a signalfd file descriptor can be viewed
+via the entry for the corresponding file descriptor in the process's
+.IR /proc/ pid /fdinfo
+directory.
+See
+.BR proc (5)
+for further details.
+.\"
+.SS Limitations
+The signalfd mechanism can't be used to receive signals that
+are synchronously generated, such as the
+.B SIGSEGV
+signal that results from accessing an invalid memory address
+or the
+.B SIGFPE
+signal that results from an arithmetic error.
+Such signals can be caught only via signal handler.
+.P
+As described above,
+in normal usage one blocks the signals that will be accepted via
+.BR signalfd ().
+If spawning a child process to execute a helper program
+(that does not need the signalfd file descriptor),
+then, after the call to
+.BR fork (2),
+you will normally want to unblock those signals before calling
+.BR execve (2),
+so that the helper program can see any signals that it expects to see.
+Be aware, however,
+that this won't be possible in the case of a helper program spawned
+behind the scenes by any library function that the program may call.
+In such cases, one must fall back to using a traditional signal
+handler that writes to a file descriptor monitored by
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7).
+.SH BUGS
+Before Linux 2.6.25, the
+.I ssi_ptr
+and
+.I ssi_int
+fields are not filled in with the data accompanying a signal sent by
+.BR sigqueue (3).
+.\" The fix also was put into Linux 2.6.24.5
+.SH EXAMPLES
+The program below accepts the signals
+.B SIGINT
+and
+.B SIGQUIT
+via a signalfd file descriptor.
+The program terminates after accepting a
+.B SIGQUIT
+signal.
+The following shell session demonstrates the use of the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./signalfd_demo"
+.BR "\[ha]C" "                   # Control\-C generates SIGINT"
+Got SIGINT
+.B \[ha]C
+Got SIGINT
+\fB\[ha]\e\fP                    # Control\-\e generates SIGQUIT
+Got SIGQUIT
+$
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (signalfd.c)
+.EX
+#include <err.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/signalfd.h>
+#include <unistd.h>
+\&
+int
+main(void)
+{
+    int                      sfd;
+    ssize_t                  s;
+    sigset_t                 mask;
+    struct signalfd_siginfo  fdsi;
+\&
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGINT);
+    sigaddset(&mask, SIGQUIT);
+\&
+    /* Block signals so that they aren\[aq]t handled
+       according to their default dispositions. */
+\&
+    if (sigprocmask(SIG_BLOCK, &mask, NULL) == \-1)
+        err(EXIT_FAILURE, "sigprocmask");
+\&
+    sfd = signalfd(\-1, &mask, 0);
+    if (sfd == \-1)
+        err(EXIT_FAILURE, "signalfd");
+\&
+    for (;;) {
+        s = read(sfd, &fdsi, sizeof(fdsi));
+        if (s != sizeof(fdsi))
+            err(EXIT_FAILURE, "read");
+\&
+        if (fdsi.ssi_signo == SIGINT) {
+            printf("Got SIGINT\en");
+        } else if (fdsi.ssi_signo == SIGQUIT) {
+            printf("Got SIGQUIT\en");
+            exit(EXIT_SUCCESS);
+        } else {
+            printf("Read unexpected signal\en");
+        }
+    }
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR eventfd (2),
+.BR poll (2),
+.BR read (2),
+.BR select (2),
+.BR sigaction (2),
+.BR sigprocmask (2),
+.BR sigwaitinfo (2),
+.BR timerfd_create (2),
+.BR sigsetops (3),
+.BR sigwait (3),
+.BR epoll (7),
+.BR signal (7)
diff --git a/man/man2/signalfd4.2 b/man/man2/signalfd4.2
new file mode 100644
index 000000000..8dbea5cb6
--- /dev/null
+++ b/man/man2/signalfd4.2
@@ -0,0 +1 @@
+.so man2/signalfd.2
diff --git a/man/man2/sigpending.2 b/man/man2/sigpending.2
new file mode 100644
index 000000000..0562440dc
--- /dev/null
+++ b/man/man2/sigpending.2
@@ -0,0 +1,110 @@
+.\" Copyright (c) 2005 Michael Kerrisk
+.\" based on earlier work by faith@cs.unc.edu and
+.\" Mike Battersby <mib@deakin.edu.au>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2
+.\"
+.TH sigpending 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigpending, rt_sigpending \- examine pending signals
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigpending(sigset_t *" set );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigpending ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+.BR sigpending ()
+returns the set of signals that are pending for delivery to the calling
+thread (i.e., the signals which have been raised while blocked).
+The mask of pending signals is returned in
+.IR set .
+.SH RETURN VALUE
+.BR sigpending ()
+returns 0 on success.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I set
+points to memory which is not a valid part of the process address space.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SS C library/kernel differences
+The original Linux system call was named
+.BR sigpending ().
+However, with the addition of real-time signals in Linux 2.2,
+the fixed-size, 32-bit
+.I sigset_t
+argument supported by that system call was no longer fit for purpose.
+Consequently, a new system call,
+.BR rt_sigpending (),
+was added to support an enlarged
+.I sigset_t
+type.
+The new system call takes a second argument,
+.IR "size_t sigsetsize" ,
+which specifies the size in bytes of the signal set in
+.IR set .
+.\" This argument is currently required to be less than or equal to
+.\" .IR sizeof(sigset_t)
+.\" (or the error
+.\" .B EINVAL
+.\" results).
+The glibc
+.BR sigpending ()
+wrapper function hides these details from us, transparently calling
+.BR rt_sigpending ()
+when the kernel provides it.
+.SH NOTES
+See
+.BR sigsetops (3)
+for details on manipulating signal sets.
+.P
+If a signal is both blocked and has a disposition of "ignored", it is
+.I not
+added to the mask of pending signals when generated.
+.P
+The set of signals that is pending for a thread
+is the union of the set of signals that is pending for that thread
+and the set of signals that is pending for the process as a whole; see
+.BR signal (7).
+.P
+A child created via
+.BR fork (2)
+initially has an empty pending signal set;
+the pending signal set is preserved across an
+.BR execve (2).
+.SH BUGS
+Up to and including glibc 2.2.1,
+there is a bug in the wrapper function for
+.BR sigpending ()
+which means that information about pending real-time signals
+is not correctly returned.
+.SH SEE ALSO
+.BR kill (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR sigprocmask (2),
+.BR sigsuspend (2),
+.BR sigsetops (3),
+.BR signal (7)
diff --git a/man/man2/sigprocmask.2 b/man/man2/sigprocmask.2
new file mode 100644
index 000000000..89838a51d
--- /dev/null
+++ b/man/man2/sigprocmask.2
@@ -0,0 +1,224 @@
+.\" Copyright (c) 2005 Michael Kerrisk
+.\" based on earlier work by faith@cs.unc.edu and
+.\" Mike Battersby <mib@deakin.edu.au>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2
+.\"
+.TH sigprocmask 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigprocmask, rt_sigprocmask \- examine and change blocked signals
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.B #include <signal.h>
+.P
+.nf
+/* Prototype for the glibc wrapper function */
+.BI "int sigprocmask(int " how ", const sigset_t *_Nullable restrict " set ,
+.BI "                           sigset_t *_Nullable restrict " oldset );
+.P
+.BR "#include <signal.h>" "           /* Definition of " SIG_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+/* Prototype for the underlying system call */
+.BI "int syscall(SYS_rt_sigprocmask, int " how ,
+.BI "                           const kernel_sigset_t *_Nullable " set ,
+.BI "                           kernel_sigset_t *_Nullable " oldset ,
+.BI "                           size_t " sigsetsize );
+.P
+/* Prototype for the legacy system call */
+.BI "[[deprecated]] int syscall(SYS_sigprocmask, int " how ,
+.BI "                           const old_kernel_sigset_t *_Nullable " set ,
+.BI "                           old_kernel_sigset_t *_Nullable " oldset );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigprocmask ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+.BR sigprocmask ()
+is used to fetch and/or change the signal mask of the calling thread.
+The signal mask is the set of signals whose delivery is currently
+blocked for the caller
+(see also
+.BR signal (7)
+for more details).
+.P
+The behavior of the call is dependent on the value of
+.IR how ,
+as follows.
+.TP
+.B SIG_BLOCK
+The set of blocked signals is the union of the current set and the
+.I set
+argument.
+.TP
+.B SIG_UNBLOCK
+The signals in
+.I set
+are removed from the current set of blocked signals.
+It is permissible to attempt to unblock a signal which is not blocked.
+.TP
+.B SIG_SETMASK
+The set of blocked signals is set to the argument
+.IR set .
+.P
+If
+.I oldset
+is non-NULL, the previous value of the signal mask is stored in
+.IR oldset .
+.P
+If
+.I set
+is NULL, then the signal mask is unchanged (i.e.,
+.I how
+is ignored),
+but the current value of the signal mask is nevertheless returned in
+.I oldset
+(if it is not NULL).
+.P
+A set of functions for modifying and inspecting variables of type
+.I sigset_t
+("signal sets") is described in
+.BR sigsetops (3).
+.P
+The use of
+.BR sigprocmask ()
+is unspecified in a multithreaded process; see
+.BR pthread_sigmask (3).
+.SH RETURN VALUE
+.BR sigprocmask ()
+returns 0 on success.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+The
+.I set
+or
+.I oldset
+argument points outside the process's allocated address space.
+.TP
+.B EINVAL
+Either the value specified in
+.I how
+was invalid or the kernel does not support the size passed in
+.I sigsetsize.
+.SH VERSIONS
+.SS C library/kernel differences
+The kernel's definition of
+.I sigset_t
+differs in size from that used
+by the C library.
+In this manual page, the former is referred to as
+.I kernel_sigset_t
+(it is nevertheless named
+.I sigset_t
+in the kernel sources).
+.P
+The glibc wrapper function for
+.BR sigprocmask ()
+silently ignores attempts to block the two real-time signals that
+are used internally by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.P
+The original Linux system call was named
+.BR sigprocmask ().
+However, with the addition of real-time signals in Linux 2.2,
+the fixed-size, 32-bit
+.I sigset_t
+(referred to as
+.I old_kernel_sigset_t
+in this manual page)
+type supported by that system call was no longer fit for purpose.
+Consequently, a new system call,
+.BR rt_sigprocmask (),
+was added to support an enlarged
+.I sigset_t
+type
+(referred to as
+.I kernel_sigset_t
+in this manual page).
+The new system call takes a fourth argument,
+.IR "size_t sigsetsize" ,
+which specifies the size in bytes of the signal sets in
+.I set
+and
+.IR oldset .
+This argument is currently required to have a fixed architecture specific value
+(equal to
+.IR sizeof(kernel_sigset_t) ).
+.\" sizeof(kernel_sigset_t) == _NSIG / 8,
+.\" which equals to 8 on most architectures, but e.g. on MIPS it's 16.
+.P
+The glibc
+.BR sigprocmask ()
+wrapper function hides these details from us, transparently calling
+.BR rt_sigprocmask ()
+when the kernel provides it.
+.\"
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+It is not possible to block
+.BR SIGKILL " or " SIGSTOP .
+Attempts to do so are silently ignored.
+.P
+Each of the threads in a process has its own signal mask.
+.P
+A child created via
+.BR fork (2)
+inherits a copy of its parent's signal mask;
+the signal mask is preserved across
+.BR execve (2).
+.P
+If
+.BR SIGBUS ,
+.BR SIGFPE ,
+.BR SIGILL ,
+or
+.B SIGSEGV
+are generated
+while they are blocked, the result is undefined,
+unless the signal was generated by
+.BR kill (2),
+.BR sigqueue (3),
+or
+.BR raise (3).
+.P
+See
+.BR sigsetops (3)
+for details on manipulating signal sets.
+.P
+Note that it is permissible (although not very useful) to specify both
+.I set
+and
+.I oldset
+as NULL.
+.SH SEE ALSO
+.BR kill (2),
+.BR pause (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR sigpending (2),
+.BR sigsuspend (2),
+.BR pthread_sigmask (3),
+.BR sigqueue (3),
+.BR sigsetops (3),
+.BR signal (7)
diff --git a/man/man2/sigreturn.2 b/man/man2/sigreturn.2
new file mode 100644
index 000000000..1a34ef54c
--- /dev/null
+++ b/man/man2/sigreturn.2
@@ -0,0 +1,151 @@
+.\" Copyright (C) 2008, 2014, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created   Sat Aug 21 1995     Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\" Modified Tue Oct 22 22:09:03 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" 2008-06-26, mtk, added some more detail on the work done by sigreturn()
+.\" 2014-12-05, mtk, rewrote all of the rest of the original page
+.\"
+.TH sigreturn 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigreturn, rt_sigreturn \- return from signal handler and cleanup stack frame
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B int sigreturn(...);
+.fi
+.SH DESCRIPTION
+If the Linux kernel determines that an unblocked
+signal is pending for a process, then,
+at the next transition back to user mode in that process
+(e.g., upon return from a system call or
+when the process is rescheduled onto the CPU),
+it creates a new frame on the user-space stack where it
+saves various pieces of process context
+(processor status word, registers, signal mask, and signal stack settings).
+.\" See arch/x86/kernel/signal.c::__setup_frame() [in Linux 3.17 source code]
+.P
+The kernel also arranges that, during the transition back to user mode,
+the signal handler is called, and that, upon return from the handler,
+control passes to a piece of user-space code commonly called
+the "signal trampoline".
+The signal trampoline code in turn calls
+.BR sigreturn ().
+.P
+This
+.BR sigreturn ()
+call undoes everything that was
+done\[em]changing the process's signal mask, switching signal stacks (see
+.BR sigaltstack "(2))\[em]in"
+order to invoke the signal handler.
+Using the information that was earlier saved on the user-space stack
+.BR sigreturn ()
+restores the process's signal mask, switches stacks,
+and restores the process's context
+(processor flags and registers,
+including the stack pointer and instruction pointer),
+so that the process resumes execution
+at the point where it was interrupted by the signal.
+.SH RETURN VALUE
+.BR sigreturn ()
+never returns.
+.SH VERSIONS
+Many UNIX-type systems have a
+.BR sigreturn ()
+system call or near equivalent.
+However, this call is not specified in POSIX,
+and details of its behavior vary across systems.
+.SH STANDARDS
+None.
+.SH NOTES
+.BR sigreturn ()
+exists only to allow the implementation of signal handlers.
+It should
+.B never
+be called directly.
+(Indeed, a simple
+.BR sigreturn ()
+.\" See sysdeps/unix/sysv/linux/sigreturn.c and
+.\" signal/sigreturn.c in the glibc source
+wrapper in the GNU C library simply returns \-1, with
+.I errno
+set to
+.BR ENOSYS .)
+Details of the arguments (if any) passed to
+.BR sigreturn ()
+vary depending on the architecture.
+(On some architectures, such as x86-64,
+.BR sigreturn ()
+takes no arguments, since all of the information that it requires
+is available in the stack frame that was previously created by the
+kernel on the user-space stack.)
+.P
+Once upon a time, UNIX systems placed the signal trampoline code
+onto the user stack.
+Nowadays, pages of the user stack are protected so as to
+disallow code execution.
+Thus, on contemporary Linux systems, depending on the architecture,
+the signal trampoline code lives either in the
+.BR vdso (7)
+or in the C library.
+In the latter case,
+.\" See, for example, sysdeps/unix/sysv/linux/i386/sigaction.c and
+.\" sysdeps/unix/sysv/linux/x86_64/sigaction.c in the glibc (2.20) source.
+the C library's
+.BR sigaction (2)
+wrapper function informs the kernel of the location of the trampoline code
+by placing its address in the
+.I sa_restorer
+field of the
+.I sigaction
+structure,
+and sets the
+.B SA_RESTORER
+flag in the
+.I sa_flags
+field.
+.P
+The saved process context information is placed in a
+.I ucontext_t
+structure (see
+.IR <sys/ucontext.h> ).
+That structure is visible within the signal handler
+as the third argument of a handler established via
+.BR sigaction (2)
+with the
+.B SA_SIGINFO
+flag.
+.P
+On some other UNIX systems,
+the operation of the signal trampoline differs a little.
+In particular, on some systems, upon transitioning back to user mode,
+the kernel passes control to the trampoline (rather than the signal handler),
+and the trampoline code calls the signal handler (and then calls
+.BR sigreturn ()
+once the handler returns).
+.\"
+.SS C library/kernel differences
+The original Linux system call was named
+.BR sigreturn ().
+However, with the addition of real-time signals in Linux 2.2,
+a new system call,
+.BR rt_sigreturn ()
+was added to support an enlarged
+.I sigset_t
+type.
+The GNU C library
+hides these details from us, transparently employing
+.BR rt_sigreturn ()
+when the kernel provides it.
+.\"
+.SH SEE ALSO
+.BR kill (2),
+.BR restart_syscall (2),
+.BR sigaltstack (2),
+.BR signal (2),
+.BR getcontext (3),
+.BR signal (7),
+.BR vdso (7)
diff --git a/man/man2/sigsuspend.2 b/man/man2/sigsuspend.2
new file mode 100644
index 000000000..01f9c9dcc
--- /dev/null
+++ b/man/man2/sigsuspend.2
@@ -0,0 +1,131 @@
+.\" Copyright (c) 2005 Michael Kerrisk
+.\" based on earlier work by faith@cs.unc.edu and
+.\" Mike Battersby <mib@deakin.edu.au>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2
+.\"
+.TH sigsuspend 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigsuspend, rt_sigsuspend \- wait for a signal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigsuspend(const sigset_t *" mask );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigsuspend ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+.BR sigsuspend ()
+temporarily replaces the signal mask of the calling thread with the
+mask given by
+.I mask
+and then suspends the thread until delivery of a signal whose
+action is to invoke a signal handler or to terminate a process.
+.P
+If the signal terminates the process, then
+.BR sigsuspend ()
+does not return.
+If the signal is caught, then
+.BR sigsuspend ()
+returns after the signal handler returns,
+and the signal mask is restored to the state before the call to
+.BR sigsuspend ().
+.P
+It is not possible to block
+.B SIGKILL
+or
+.BR SIGSTOP ;
+specifying these signals in
+.IR mask ,
+has no effect on the thread's signal mask.
+.SH RETURN VALUE
+.BR sigsuspend ()
+always returns \-1, with
+.I errno
+set to indicate the error (normally,
+.BR EINTR ).
+.SH ERRORS
+.TP
+.B EFAULT
+.I mask
+points to memory which is not a valid part of the process address space.
+.TP
+.B EINTR
+The call was interrupted by a signal;
+.BR signal (7).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SS C library/kernel differences
+The original Linux system call was named
+.BR sigsuspend ().
+However, with the addition of real-time signals in Linux 2.2,
+the fixed-size, 32-bit
+.I sigset_t
+type supported by that system call was no longer fit for purpose.
+Consequently, a new system call,
+.BR rt_sigsuspend (),
+was added to support an enlarged
+.I sigset_t
+type.
+The new system call takes a second argument,
+.IR "size_t sigsetsize" ,
+which specifies the size in bytes of the signal set in
+.IR mask .
+This argument is currently required to have the value
+.I sizeof(sigset_t)
+(or the error
+.B EINVAL
+results).
+The glibc
+.BR sigsuspend ()
+wrapper function hides these details from us, transparently calling
+.BR rt_sigsuspend ()
+when the kernel provides it.
+.\"
+.SH NOTES
+Normally,
+.BR sigsuspend ()
+is used in conjunction with
+.BR sigprocmask (2)
+in order to prevent delivery of a signal during the execution of a
+critical code section.
+The caller first blocks the signals with
+.BR sigprocmask (2).
+When the critical code has completed, the caller then waits for the
+signals by calling
+.BR sigsuspend ()
+with the signal mask that was returned by
+.BR sigprocmask (2)
+(in the
+.I oldset
+argument).
+.P
+See
+.BR sigsetops (3)
+for details on manipulating signal sets.
+.SH SEE ALSO
+.BR kill (2),
+.BR pause (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR sigprocmask (2),
+.BR sigwaitinfo (2),
+.BR sigsetops (3),
+.BR sigwait (3),
+.BR signal (7)
diff --git a/man/man2/sigtimedwait.2 b/man/man2/sigtimedwait.2
new file mode 100644
index 000000000..1b13df15d
--- /dev/null
+++ b/man/man2/sigtimedwait.2
@@ -0,0 +1 @@
+.so man2/sigwaitinfo.2
diff --git a/man/man2/sigwaitinfo.2 b/man/man2/sigwaitinfo.2
new file mode 100644
index 000000000..5d302dfb5
--- /dev/null
+++ b/man/man2/sigwaitinfo.2
@@ -0,0 +1,231 @@
+.\" Copyright (c) 2002 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sigwaitinfo 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigwaitinfo, sigtimedwait, rt_sigtimedwait \- synchronously wait
+for queued signals
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigwaitinfo(const sigset_t *restrict " set ,
+.BI "                siginfo_t *_Nullable restrict " info );
+.BI "int sigtimedwait(const sigset_t *restrict " set ,
+.BI "                siginfo_t *_Nullable restrict " info ,
+.BI "                const struct timespec *restrict " timeout );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigwaitinfo (),
+.BR sigtimedwait ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+.BR sigwaitinfo ()
+suspends execution of the calling thread until one of the signals in
+.I set
+is pending
+(If one of the signals in
+.I set
+is already pending for the calling thread,
+.BR sigwaitinfo ()
+will return immediately.)
+.P
+.BR sigwaitinfo ()
+removes the signal from the set of pending
+signals and returns the signal number as its function result.
+If the
+.I info
+argument is not NULL,
+then the buffer that it points to is used to return a structure of type
+.I siginfo_t
+(see
+.BR sigaction (2))
+containing information about the signal.
+.P
+If multiple signals in
+.I set
+are pending for the caller, the signal that is retrieved by
+.BR sigwaitinfo ()
+is determined according to the usual ordering rules; see
+.BR signal (7)
+for further details.
+.P
+.BR sigtimedwait ()
+operates in exactly the same way as
+.BR sigwaitinfo ()
+except that it has an additional argument,
+.IR timeout ,
+which specifies the interval for which
+the thread is suspended waiting for a signal.
+(This interval will be rounded up to the system clock granularity,
+and kernel scheduling delays mean that the interval
+may overrun by a small amount.)
+This argument is a
+.BR timespec (3)
+structure.
+.P
+If both fields of this structure are specified as 0, a poll is performed:
+.BR sigtimedwait ()
+returns immediately, either with information about a signal that
+was pending for the caller, or with an error
+if none of the signals in
+.I set
+was pending.
+.SH RETURN VALUE
+On success, both
+.BR sigwaitinfo ()
+and
+.BR sigtimedwait ()
+return a signal number (i.e., a value greater than zero).
+On failure both calls return \-1, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+No signal in
+.I set
+became pending within the
+.I timeout
+period specified to
+.BR sigtimedwait ().
+.TP
+.B EINTR
+The wait was interrupted by a signal handler; see
+.BR signal (7).
+(This handler was for a signal other than one of those in
+.IR set .)
+.TP
+.B EINVAL
+.I timeout
+was invalid.
+.SH VERSIONS
+.SS C library/kernel differences
+On Linux,
+.BR sigwaitinfo ()
+is a library function implemented on top of
+.BR sigtimedwait ().
+.P
+The glibc wrapper functions for
+.BR sigwaitinfo ()
+and
+.BR sigtimedwait ()
+silently ignore attempts to wait for the two real-time signals that
+are used internally by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.P
+The original Linux system call was named
+.BR sigtimedwait ().
+However, with the addition of real-time signals in Linux 2.2,
+the fixed-size, 32-bit
+.I sigset_t
+type supported by that system call was no longer fit for purpose.
+Consequently, a new system call,
+.BR rt_sigtimedwait (),
+was added to support an enlarged
+.I sigset_t
+type.
+The new system call takes a fourth argument,
+.IR "size_t sigsetsize" ,
+which specifies the size in bytes of the signal set in
+.IR set .
+This argument is currently required to have the value
+.I sizeof(sigset_t)
+(or the error
+.B EINVAL
+results).
+The glibc
+.BR sigtimedwait ()
+wrapper function hides these details from us, transparently calling
+.BR rt_sigtimedwait ()
+when the kernel provides it.
+.\"
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+In normal usage, the calling program blocks the signals in
+.I set
+via a prior call to
+.BR sigprocmask (2)
+(so that the default disposition for these signals does not occur if they
+become pending between successive calls to
+.BR sigwaitinfo ()
+or
+.BR sigtimedwait ())
+and does not establish handlers for these signals.
+In a multithreaded program,
+the signal should be blocked in all threads, in order to prevent
+the signal being treated according to its default disposition in
+a thread other than the one calling
+.BR sigwaitinfo ()
+or
+.BR sigtimedwait ()).
+.P
+The set of signals that is pending for a given thread is the
+union of the set of signals that is pending specifically for that thread
+and the set of signals that is pending for the process as a whole (see
+.BR signal (7)).
+.P
+Attempts to wait for
+.B SIGKILL
+and
+.B SIGSTOP
+are silently ignored.
+.P
+If multiple threads of a process are blocked
+waiting for the same signal(s) in
+.BR sigwaitinfo ()
+or
+.BR sigtimedwait (),
+then exactly one of the threads will actually receive the
+signal if it becomes pending for the process as a whole;
+which of the threads receives the signal is indeterminate.
+.P
+.BR sigwaitinfo ()
+or
+.BR sigtimedwait (),
+can't be used to receive signals that
+are synchronously generated, such as the
+.B SIGSEGV
+signal that results from accessing an invalid memory address
+or the
+.B SIGFPE
+signal that results from an arithmetic error.
+Such signals can be caught only via signal handler.
+.P
+POSIX leaves the meaning of a NULL value for the
+.I timeout
+argument of
+.BR sigtimedwait ()
+unspecified, permitting the possibility that this has the same meaning
+as a call to
+.BR sigwaitinfo (),
+and indeed this is what is done on Linux.
+.SH SEE ALSO
+.BR kill (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR signalfd (2),
+.BR sigpending (2),
+.BR sigprocmask (2),
+.BR sigqueue (3),
+.BR sigsetops (3),
+.BR sigwait (3),
+.BR timespec (3),
+.BR signal (7),
+.BR time (7)
diff --git a/man/man2/socket.2 b/man/man2/socket.2
new file mode 100644
index 000000000..4490f6c1a
--- /dev/null
+++ b/man/man2/socket.2
@@ -0,0 +1,493 @@
+'\" t
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     $Id: socket.2,v 1.4 1999/05/13 11:33:42 freitag Exp $
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998, 1999 by Andi Kleen <ak@muc.de>
+.\" Modified 2002-07-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH socket 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+socket \- create an endpoint for communication
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int socket(int " domain ", int " type ", int " protocol );
+.fi
+.SH DESCRIPTION
+.BR socket ()
+creates an endpoint for communication and returns a file descriptor
+that refers to that endpoint.
+The file descriptor returned by a successful call will be
+the lowest-numbered file descriptor not currently open for the process.
+.P
+The
+.I domain
+argument specifies a communication domain; this selects the protocol
+family which will be used for communication.
+These families are defined in
+.IR <sys/socket.h> .
+The formats currently understood by the Linux kernel include:
+.TS
+tab(:);
+l1 lw40 l.
+Name:Purpose:Man page
+T{
+.B AF_UNIX
+T}:T{
+Local communication
+T}:T{
+.BR unix (7)
+T}
+T{
+.B AF_LOCAL
+T}:T{
+Synonym for
+.B AF_UNIX
+T}:T{
+T}
+T{
+.B AF_INET
+T}:IPv4 Internet protocols:T{
+.BR ip (7)
+T}
+T{
+.B AF_AX25
+T}:T{
+Amateur radio AX.25 protocol
+T}:T{
+.\" Part of ax25-tools
+.BR ax25 (4)
+T}
+T{
+.B AF_IPX
+T}:IPX \- Novell protocols:
+T{
+.B AF_APPLETALK
+T}:AppleTalk:T{
+.BR ddp (7)
+T}
+T{
+.B AF_X25
+T}:ITU-T X.25 / ISO/IEC\~8208 protocol:T{
+.BR x25 (7)
+T}
+T{
+.B AF_INET6
+T}:IPv6 Internet protocols:T{
+.BR ipv6 (7)
+T}
+T{
+.B AF_DECnet
+T}:T{
+DECet protocol sockets
+T}
+T{
+.B AF_KEY
+T}:T{
+Key management protocol, originally developed for usage with IPsec
+T}
+T{
+.B AF_NETLINK
+T}:T{
+Kernel user interface device
+T}:T{
+.BR netlink (7)
+T}
+T{
+.B AF_PACKET
+T}:T{
+Low-level packet interface
+T}:T{
+.BR packet (7)
+T}
+T{
+.B AF_RDS
+T}:T{
+.\" commit: 639b321b4d8f4e412bfbb2a4a19bfebc1e68ace4
+Reliable Datagram Sockets (RDS) protocol
+T}:T{
+.\" rds-tools: https://github.com/oracle/rds-tools/blob/master/rds.7
+.\" rds-tools: https://github.com/oracle/rds-tools/blob/master/rds-rdma.7
+.BR rds (7)
+.br
+.BR rds\-rdma (7)
+T}
+T{
+.B AF_PPPOX
+T}:T{
+Generic PPP transport layer, for setting up L2 tunnels
+(L2TP and PPPoE)
+T}
+T{
+.B AF_LLC
+T}:T{
+.\" linux-history commit: 34beb106cde7da233d4df35dd3d6cf4fee937caa
+Logical link control (IEEE 802.2 LLC) protocol
+T}
+T{
+.B AF_IB
+T}:T{
+.\" commits: 8d36eb01da5d371f..ce117ffac2e93334
+InfiniBand native addressing
+T}
+T{
+.B AF_MPLS
+T}:T{
+.\" commits: 0189197f441602acdca3f97750d392a895b778fd
+Multiprotocol Label Switching
+T}
+T{
+.B AF_CAN
+T}:T{
+.\" commits: 8dbde28d9711475a..5423dd67bd0108a1
+Controller Area Network automotive bus protocol
+T}
+T{
+.B AF_TIPC
+T}:T{
+.\" commits: b97bf3fd8f6a16966d4f18983b2c40993ff937d4
+TIPC, "cluster domain sockets" protocol
+T}
+T{
+.B AF_BLUETOOTH
+T}:T{
+.\" commits: 8d36eb01da5d371f..ce117ffac2e93334
+Bluetooth low-level socket protocol
+T}
+T{
+.B AF_ALG
+T}:T{
+.\" commit: 03c8efc1ffeb6b82a22c1af8dd908af349563314
+Interface to kernel crypto API
+T}
+T{
+.B AF_VSOCK
+T}:T{
+.\" commit: d021c344051af91f42c5ba9fdedc176740cbd238
+VSOCK (originally "VMWare VSockets") protocol
+for hypervisor-guest communication
+T}:T{
+.BR vsock (7)
+T}
+T{
+.B AF_KCM
+T}:T{
+.\" commit: 03c8efc1ffeb6b82a22c1af8dd908af349563314
+KCM (kernel connection multiplexer) interface
+T}
+T{
+.B AF_XDP
+T}:T{
+.\" commit: c0c77d8fb787cfe0c3fca689c2a30d1dad4eaba7
+XDP (express data path) interface
+T}
+.TE
+.P
+Further details of the above address families,
+as well as information on several other address families, can be found in
+.BR address_families (7).
+.P
+The socket has the indicated
+.IR type ,
+which specifies the communication semantics.
+Currently defined types
+are:
+.TP 16
+.B SOCK_STREAM
+Provides sequenced, reliable, two-way, connection-based byte streams.
+An out-of-band data transmission mechanism may be supported.
+.TP
+.B SOCK_DGRAM
+Supports datagrams (connectionless, unreliable messages of a fixed
+maximum length).
+.TP
+.B SOCK_SEQPACKET
+Provides a sequenced, reliable, two-way connection-based data
+transmission path for datagrams of fixed maximum length; a consumer is
+required to read an entire packet with each input system call.
+.TP
+.B SOCK_RAW
+Provides raw network protocol access.
+.TP
+.B SOCK_RDM
+Provides a reliable datagram layer that does not guarantee ordering.
+.TP
+.B SOCK_PACKET
+Obsolete and should not be used in new programs;
+see
+.BR packet (7).
+.P
+Some socket types may not be implemented by all protocol families.
+.P
+Since Linux 2.6.27, the
+.I type
+argument serves a second purpose:
+in addition to specifying a socket type,
+it may include the bitwise OR of any of the following values,
+to modify the behavior of
+.BR socket ():
+.TP 16
+.B SOCK_NONBLOCK
+Set the
+.B O_NONBLOCK
+file status flag on the open file description (see
+.BR open (2))
+referred to by the new file descriptor.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
+.TP
+.B SOCK_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.P
+The
+.I protocol
+specifies a particular protocol to be used with the socket.
+Normally only a single protocol exists to support a particular
+socket type within a given protocol family, in which case
+.I protocol
+can be specified as 0.
+However, it is possible that many protocols may exist, in
+which case a particular protocol must be specified in this manner.
+The protocol number to use is specific to the \*(lqcommunication domain\*(rq
+in which communication is to take place; see
+.BR protocols (5).
+See
+.BR getprotoent (3)
+on how to map protocol name strings to protocol numbers.
+.P
+Sockets of type
+.B SOCK_STREAM
+are full-duplex byte streams.
+They do not preserve
+record boundaries.
+A stream socket must be in
+a
+.I connected
+state before any data may be sent or received on it.
+A connection to
+another socket is created with a
+.BR connect (2)
+call.
+Once connected, data may be transferred using
+.BR read (2)
+and
+.BR write (2)
+calls or some variant of the
+.BR send (2)
+and
+.BR recv (2)
+calls.
+When a session has been completed a
+.BR close (2)
+may be performed.
+Out-of-band data may also be transmitted as described in
+.BR send (2)
+and received as described in
+.BR recv (2).
+.P
+The communications protocols which implement a
+.B SOCK_STREAM
+ensure that data is not lost or duplicated.
+If a piece of data for which
+the peer protocol has buffer space cannot be successfully transmitted
+within a reasonable length of time, then the connection is considered
+to be dead.
+When
+.B SO_KEEPALIVE
+is enabled on the socket the protocol checks in a protocol-specific
+manner if the other end is still alive.
+A
+.B SIGPIPE
+signal is raised if a process sends or receives
+on a broken stream; this causes naive processes,
+which do not handle the signal, to exit.
+.B SOCK_SEQPACKET
+sockets employ the same system calls as
+.B SOCK_STREAM
+sockets.
+The only difference is that
+.BR read (2)
+calls will return only the amount of data requested,
+and any data remaining in the arriving packet will be discarded.
+Also all message boundaries in incoming datagrams are preserved.
+.P
+.B SOCK_DGRAM
+and
+.B SOCK_RAW
+sockets allow sending of datagrams to correspondents named in
+.BR sendto (2)
+calls.
+Datagrams are generally received with
+.BR recvfrom (2),
+which returns the next datagram along with the address of its sender.
+.P
+.B SOCK_PACKET
+is an obsolete socket type to receive raw packets directly from the
+device driver.
+Use
+.BR packet (7)
+instead.
+.P
+An
+.BR fcntl (2)
+.B F_SETOWN
+operation can be used to specify a process or process group to receive a
+.B SIGURG
+signal when the out-of-band data arrives or
+.B SIGPIPE
+signal when a
+.B SOCK_STREAM
+connection breaks unexpectedly.
+This operation may also be used to set the process or process group
+that receives the I/O and asynchronous notification of I/O events via
+.BR SIGIO .
+Using
+.B F_SETOWN
+is equivalent to an
+.BR ioctl (2)
+call with the
+.B FIOSETOWN
+or
+.B SIOCSPGRP
+argument.
+.P
+When the network signals an error condition to the protocol module (e.g.,
+using an ICMP message for IP) the pending error flag is set for the socket.
+The next operation on this socket will return the error code of the pending
+error.
+For some protocols it is possible to enable a per-socket error queue
+to retrieve detailed information about the error; see
+.B IP_RECVERR
+in
+.BR ip (7).
+.P
+The operation of sockets is controlled by socket level
+.IR options .
+These options are defined in
+.IR <sys/socket.h> .
+The functions
+.BR setsockopt (2)
+and
+.BR getsockopt (2)
+are used to set and get options.
+.SH RETURN VALUE
+On success, a file descriptor for the new socket is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Permission to create a socket of the specified type and/or protocol
+is denied.
+.TP
+.B EAFNOSUPPORT
+The implementation does not support the specified address family.
+.TP
+.B EINVAL
+Unknown protocol, or protocol family not available.
+.TP
+.B EINVAL
+.\" Since Linux 2.6.27
+Invalid flags in
+.IR type .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.BR ENOBUFS " or " ENOMEM
+Insufficient memory is available.
+The socket cannot be
+created until sufficient resources are freed.
+.TP
+.B EPROTONOSUPPORT
+The protocol type or the specified protocol is not
+supported within this domain.
+.P
+Other errors may be generated by the underlying protocol modules.
+.SH STANDARDS
+POSIX.1-2008.
+.P
+.B SOCK_NONBLOCK
+and
+.B SOCK_CLOEXEC
+are Linux-specific.
+.SH HISTORY
+POSIX.1-2001, 4.4BSD.
+.P
+.BR socket ()
+appeared in 4.2BSD.
+It is generally portable to/from
+non-BSD systems supporting clones of the BSD socket layer (including
+System\ V variants).
+.P
+The manifest constants used under 4.x BSD for protocol families
+are
+.BR PF_UNIX ,
+.BR PF_INET ,
+and so on, while
+.BR AF_UNIX ,
+.BR AF_INET ,
+and so on are used for address
+families.
+However, already the BSD man page promises: "The protocol
+family generally is the same as the address family", and subsequent
+standards use AF_* everywhere.
+.SH EXAMPLES
+An example of the use of
+.BR socket ()
+is shown in
+.BR getaddrinfo (3).
+.SH SEE ALSO
+.BR accept (2),
+.BR bind (2),
+.BR close (2),
+.BR connect (2),
+.BR fcntl (2),
+.BR getpeername (2),
+.BR getsockname (2),
+.BR getsockopt (2),
+.BR ioctl (2),
+.BR listen (2),
+.BR read (2),
+.BR recv (2),
+.BR select (2),
+.BR send (2),
+.BR shutdown (2),
+.BR socketpair (2),
+.BR write (2),
+.BR getprotoent (3),
+.BR address_families (7),
+.BR ip (7),
+.BR socket (7),
+.BR tcp (7),
+.BR udp (7),
+.BR unix (7)
+.P
+\[lq]An Introductory 4.3BSD Interprocess Communication Tutorial\[rq]
+and
+\[lq]BSD Interprocess Communication Tutorial\[rq],
+reprinted in
+.I UNIX Programmer's Supplementary Documents Volume 1.
diff --git a/man/man2/socketcall.2 b/man/man2/socketcall.2
new file mode 100644
index 000000000..086ed6bdb
--- /dev/null
+++ b/man/man2/socketcall.2
@@ -0,0 +1,185 @@
+'\" t
+.\" Copyright (c) 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Tue Oct 22 22:11:53 1996 by Eric S. Raymond <esr@thyrsus.com>
+.TH socketcall 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+socketcall \- socket system calls
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/net.h>" "        /* Definition of " SYS_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_socketcall " */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_socketcall, int " call ", unsigned long *" args );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR socketcall (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR socketcall ()
+is a common kernel entry point for the socket system calls.
+.I call
+determines which socket function to invoke.
+.I args
+points to a block containing the actual arguments,
+which are passed through to the appropriate call.
+.P
+User programs should call the appropriate functions by their usual names.
+Only standard library implementors and kernel hackers need to know about
+.BR socketcall ().
+.P
+.TS
+tab(:);
+l l.
+\fIcall\fR:Man page
+T{
+.B SYS_SOCKET
+T}:T{
+.BR socket (2)
+T}
+T{
+.B SYS_BIND
+T}:T{
+.BR bind (2)
+T}
+T{
+.B SYS_CONNECT
+T}:T{
+.BR connect (2)
+T}
+T{
+.B SYS_LISTEN
+T}:T{
+.BR listen (2)
+T}
+T{
+.B SYS_ACCEPT
+T}:T{
+.BR accept (2)
+T}
+T{
+.B SYS_GETSOCKNAME
+T}:T{
+.BR getsockname (2)
+T}
+T{
+.B SYS_GETPEERNAME
+T}:T{
+.BR getpeername (2)
+T}
+T{
+.B SYS_SOCKETPAIR
+T}:T{
+.BR socketpair (2)
+T}
+T{
+.B SYS_SEND
+T}:T{
+.BR send (2)
+T}
+T{
+.B SYS_RECV
+T}:T{
+.BR recv (2)
+T}
+T{
+.B SYS_SENDTO
+T}:T{
+.BR sendto (2)
+T}
+T{
+.B SYS_RECVFROM
+T}:T{
+.BR recvfrom (2)
+T}
+T{
+.B SYS_SHUTDOWN
+T}:T{
+.BR shutdown (2)
+T}
+T{
+.B SYS_SETSOCKOPT
+T}:T{
+.BR setsockopt (2)
+T}
+T{
+.B SYS_GETSOCKOPT
+T}:T{
+.BR getsockopt (2)
+T}
+T{
+.B SYS_SENDMSG
+T}:T{
+.BR sendmsg (2)
+T}
+T{
+.B SYS_RECVMSG
+T}:T{
+.BR recvmsg (2)
+T}
+T{
+.B SYS_ACCEPT4
+T}:T{
+.BR accept4 (2)
+T}
+T{
+.B SYS_RECVMMSG
+T}:T{
+.BR recvmmsg (2)
+T}
+T{
+.B SYS_SENDMMSG
+T}:T{
+.BR sendmmsg (2)
+T}
+.TE
+.SH VERSIONS
+On some architectures\[em]for example, x86-64 and ARM\[em]there is no
+.BR socketcall ()
+system call; instead
+.BR socket (2),
+.BR accept (2),
+.BR bind (2),
+and so on really are implemented as separate system calls.
+.SH STANDARDS
+Linux.
+.P
+On x86-32,
+.BR socketcall ()
+was historically the only entry point for the sockets API.
+However, starting in Linux 4.3,
+.\" commit 9dea5dc921b5f4045a18c63eb92e84dc274d17eb
+direct system calls are provided on x86-32 for the sockets API.
+This facilitates the creation of
+.BR seccomp (2)
+filters that filter sockets system calls
+(for new user-space binaries that are compiled
+to use the new entry points)
+and also provides a (very) small performance improvement.
+.SH SEE ALSO
+.BR accept (2),
+.BR bind (2),
+.BR connect (2),
+.BR getpeername (2),
+.BR getsockname (2),
+.BR getsockopt (2),
+.BR listen (2),
+.BR recv (2),
+.BR recvfrom (2),
+.BR recvmsg (2),
+.BR send (2),
+.BR sendmsg (2),
+.BR sendto (2),
+.BR setsockopt (2),
+.BR shutdown (2),
+.BR socket (2),
+.BR socketpair (2)
diff --git a/man/man2/socketpair.2 b/man/man2/socketpair.2
new file mode 100644
index 000000000..17d3bb35c
--- /dev/null
+++ b/man/man2/socketpair.2
@@ -0,0 +1,116 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)socketpair.2	6.4 (Berkeley) 3/10/91
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2002-07-22 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2008-10-11, mtk: Add description of SOCK_NONBLOCK and SOCK_CLOEXEC
+.\"
+.TH socketpair 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+socketpair \- create a pair of connected sockets
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int socketpair(int " domain ", int " type ", int " protocol \
+", int " sv [2]);
+.fi
+.SH DESCRIPTION
+The
+.BR socketpair ()
+call creates an unnamed pair of connected sockets in the specified
+.IR domain ,
+of the specified
+.IR type ,
+and using the optionally specified
+.IR protocol .
+For further details of these arguments, see
+.BR socket (2).
+.P
+The file descriptors used in referencing the new sockets are returned in
+.I sv[0]
+and
+.IR sv[1] .
+The two sockets are indistinguishable.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned,
+.I errno
+is set to indicate the error, and
+.I sv
+is left unchanged
+.P
+On Linux (and other systems),
+.BR socketpair ()
+does not modify
+.I sv
+on failure.
+A requirement standardizing this behavior was added in POSIX.1-2008 TC2.
+.\" http://austingroupbugs.net/view.php?id=483
+.SH ERRORS
+.TP
+.B EAFNOSUPPORT
+The specified address family is not supported on this machine.
+.TP
+.B EFAULT
+The address
+.I sv
+does not specify a valid part of the process address space.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B EOPNOTSUPP
+The specified protocol does not support creation of socket pairs.
+.TP
+.B EPROTONOSUPPORT
+The specified protocol is not supported on this machine.
+.SH VERSIONS
+On Linux, the only supported domains for this call are
+.B AF_UNIX
+(or synonymously,
+.BR AF_LOCAL )
+and
+.B AF_TIPC
+.\" commit: 70b03759e9ecfae400605fa34f3d7154cccbbba3
+(since Linux 4.12).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.4BSD.
+.P
+.BR socketpair ()
+first appeared in 4.2BSD.
+It is generally portable to/from
+non-BSD systems supporting clones of the BSD socket layer (including
+System\ V variants).
+.P
+Since Linux 2.6.27,
+.BR socketpair ()
+supports the
+.B SOCK_NONBLOCK
+and
+.B SOCK_CLOEXEC
+flags in the
+.I type
+argument, as described in
+.BR socket (2).
+.SH SEE ALSO
+.BR pipe (2),
+.BR read (2),
+.BR socket (2),
+.BR write (2),
+.BR socket (7),
+.BR unix (7)
diff --git a/man/man2/splice.2 b/man/man2/splice.2
new file mode 100644
index 000000000..e5d05a05c
--- /dev/null
+++ b/man/man2/splice.2
@@ -0,0 +1,266 @@
+.\" This manpage is Copyright (C) 2006 Jens Axboe
+.\" and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH splice 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+splice \- splice data to/from a pipe
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #define _FILE_OFFSET_BITS  64
+.B #include <fcntl.h>
+.P
+.BI "ssize_t splice(int " fd_in ", off_t *_Nullable " off_in ,
+.BI "               int " fd_out ", off_t *_Nullable " off_out ,
+.BI "               size_t " len ", unsigned int " flags );
+.\" Return type was long before glibc 2.7
+.fi
+.SH DESCRIPTION
+.BR splice ()
+moves data between two file descriptors
+without copying between kernel address space and user address space.
+It transfers up to
+.I len
+bytes of data from the file descriptor
+.I fd_in
+to the file descriptor
+.IR fd_out ,
+where one of the file descriptors must refer to a pipe.
+.P
+The following semantics apply for
+.I fd_in
+and
+.IR off_in :
+.IP \[bu] 3
+If
+.I fd_in
+refers to a pipe, then
+.I off_in
+must be NULL.
+.IP \[bu]
+If
+.I fd_in
+does not refer to a pipe and
+.I off_in
+is NULL, then bytes are read from
+.I fd_in
+starting from the file offset,
+and the file offset is adjusted appropriately.
+.IP \[bu]
+If
+.I fd_in
+does not refer to a pipe and
+.I off_in
+is not NULL, then
+.I off_in
+must point to a buffer which specifies the starting
+offset from which bytes will be read from
+.IR fd_in ;
+in this case, the file offset of
+.I fd_in
+is not changed.
+.P
+Analogous statements apply for
+.I fd_out
+and
+.IR off_out .
+.P
+The
+.I flags
+argument is a bit mask that is composed by ORing together
+zero or more of the following values:
+.TP
+.B SPLICE_F_MOVE
+Attempt to move pages instead of copying.
+This is only a hint to the kernel:
+pages may still be copied if the kernel cannot move the
+pages from the pipe, or if
+the pipe buffers don't refer to full pages.
+The initial implementation of this flag was buggy:
+therefore starting in Linux 2.6.21 it is a no-op
+(but is still permitted in a
+.BR splice ()
+call);
+in the future, a correct implementation may be restored.
+.TP
+.B SPLICE_F_NONBLOCK
+Do not block on I/O.
+This makes the splice pipe operations nonblocking, but
+.BR splice ()
+may nevertheless block because the file descriptors that
+are spliced to/from may block (unless they have the
+.B O_NONBLOCK
+flag set).
+.TP
+.B SPLICE_F_MORE
+More data will be coming in a subsequent splice.
+This is a helpful hint when
+the
+.I fd_out
+refers to a socket (see also the description of
+.B MSG_MORE
+in
+.BR send (2),
+and the description of
+.B TCP_CORK
+in
+.BR tcp (7)).
+.TP
+.B SPLICE_F_GIFT
+Unused for
+.BR splice ();
+see
+.BR vmsplice (2).
+.SH RETURN VALUE
+Upon successful completion,
+.BR splice ()
+returns the number of bytes
+spliced to or from the pipe.
+.P
+A return value of 0 means end of input.
+If
+.I fd_in
+refers to a pipe, then this means that there was no data to transfer,
+and it would not make sense to block because there are no writers
+connected to the write end of the pipe.
+.P
+On error,
+.BR splice ()
+returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+.B SPLICE_F_NONBLOCK
+was specified in
+.I flags
+or one of the file descriptors had been marked as nonblocking
+.RB ( O_NONBLOCK ) ,
+and the operation would block.
+.TP
+.B EBADF
+One or both file descriptors are not valid,
+or do not have proper read-write mode.
+.TP
+.B EINVAL
+The target filesystem doesn't support splicing.
+.TP
+.B EINVAL
+The target file is opened in append mode.
+.\" The append-mode error is given since Linux 2.6.27; in earlier kernels,
+.\" splice() in append mode was broken
+.TP
+.B EINVAL
+Neither of the file descriptors refers to a pipe.
+.TP
+.B EINVAL
+An offset was given for nonseekable device (e.g., a pipe).
+.TP
+.B EINVAL
+.I fd_in
+and
+.I fd_out
+refer to the same pipe.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ESPIPE
+Either
+.I off_in
+or
+.I off_out
+was not NULL, but the corresponding file descriptor refers to a pipe.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.17,
+glibc 2.5.
+.P
+In Linux 2.6.30 and earlier,
+exactly one of
+.I fd_in
+and
+.I fd_out
+was required to be a pipe.
+Since Linux 2.6.31,
+.\" commit 7c77f0b3f9208c339a4b40737bb2cb0f0319bb8d
+both arguments may refer to pipes.
+.SH NOTES
+The three system calls
+.BR splice (),
+.BR vmsplice (2),
+and
+.BR tee (2),
+provide user-space programs with full control over an arbitrary
+kernel buffer, implemented within the kernel using the same type
+of buffer that is used for a pipe.
+In overview, these system calls perform the following tasks:
+.TP
+.BR splice ()
+moves data from the buffer to an arbitrary file descriptor, or vice versa,
+or from one buffer to another.
+.TP
+.BR tee (2)
+"copies" the data from one buffer to another.
+.TP
+.BR vmsplice (2)
+"copies" data from user space into the buffer.
+.P
+Though we talk of copying, actual copies are generally avoided.
+The kernel does this by implementing a pipe buffer as a set
+of reference-counted pointers to pages of kernel memory.
+The kernel creates "copies" of pages in a buffer by creating new
+pointers (for the output buffer) referring to the pages,
+and increasing the reference counts for the pages:
+only pointers are copied, not the pages of the buffer.
+.\"
+.\" Linus: Now, imagine using the above in a media server, for example.
+.\" Let's say that a year or two has passed, so that the video drivers
+.\" have been updated to be able to do the splice thing, and what can
+.\" you do? You can:
+.\"
+.\" - splice from the (mpeg or whatever - let's just assume that the video
+.\"   input is either digital or does the encoding on its own - like they
+.\"   pretty much all do) video input into a pipe (remember: no copies - the
+.\"   video input will just DMA directly into memory, and splice will just
+.\"   set up the pages in the pipe buffer)
+.\" - tee that pipe to split it up
+.\" - splice one end to a file (ie "save the compressed stream to disk")
+.\" - splice the other end to a real-time video decoder window for your
+.\"   real-time viewing pleasure.
+.\"
+.\" Linus: Now, the advantage of splice()/tee() is that you can
+.\" do zero-copy movement of data, and unlike sendfile() you can
+.\" do it on _arbitrary_ data (and, as shown by "tee()", it's more
+.\" than just sending the data to somebody else: you can duplicate
+.\" the data and choose to forward it to two or more different
+.\" users - for things like logging etc.).
+.\"
+.P
+.B _FILE_OFFSET_BITS
+should be defined to be 64 in code that uses non-null
+.I off_in
+or
+.I off_out
+or that takes the address of
+.BR splice ,
+if the code is intended to be portable
+to traditional 32-bit x86 and ARM platforms where
+.BR off_t 's
+width defaults to 32 bits.
+.SH EXAMPLES
+See
+.BR tee (2).
+.SH SEE ALSO
+.BR copy_file_range (2),
+.BR sendfile (2),
+.BR tee (2),
+.BR vmsplice (2),
+.BR pipe (7)
diff --git a/man/man2/spu_create.2 b/man/man2/spu_create.2
new file mode 100644
index 000000000..9f137a047
--- /dev/null
+++ b/man/man2/spu_create.2
@@ -0,0 +1,276 @@
+.\" Copyright (c) International Business Machines Corp., 2006
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" HISTORY:
+.\" 2005-09-28, created by Arnd Bergmann <arndb@de.ibm.com>
+.\" 2006-06-16, revised by Eduardo M. Fleury <efleury@br.ibm.com>
+.\" 2007-07-10, some polishing by mtk
+.\" 2007-09-28, updates for newer kernels by Jeremy Kerr <jk@ozlabs.org>
+.\"
+.TH spu_create 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+spu_create \- create a new spu context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/spu.h>" "          /* Definition of " SPU_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_spu_create, const char *" pathname \
+", unsigned int " flags ,
+.BI "            mode_t " mode ", int " neighbor_fd );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR spu_create (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR spu_create ()
+system call is used on PowerPC machines that implement the
+Cell Broadband Engine Architecture in order to access Synergistic
+Processor Units (SPUs).
+It creates a new logical context for an SPU in
+.I pathname
+and returns a file descriptor associated with it.
+.I pathname
+must refer to a nonexistent directory in the mount point of
+the SPU filesystem
+.RB ( spufs ).
+If
+.BR spu_create ()
+is successful, a directory is created at
+.I pathname
+and it is populated with the files described in
+.BR spufs (7).
+.P
+When a context is created,
+the returned file descriptor can only be passed to
+.BR spu_run (2),
+used as the
+.I dirfd
+argument to the
+.B *at
+family of system calls (e.g.,
+.BR openat (2)),
+or closed;
+other operations are not defined.
+A logical SPU
+context is destroyed (along with all files created within the context's
+.I pathname
+directory) once the last reference to the context has gone;
+this usually occurs when the file descriptor returned by
+.BR spu_create ()
+is closed.
+.P
+The
+.I mode
+argument (minus any bits set in the process's
+.BR umask (2))
+specifies the permissions used for creating the new directory in
+.BR spufs .
+See
+.BR stat (2)
+for a full list of the possible
+.I mode
+values.
+.P
+The
+.I neighbor_fd
+is used only when the
+.B SPU_CREATE_AFFINITY_SPU
+flag is specified; see below.
+.P
+The
+.I flags
+argument can be zero or any bitwise OR-ed
+combination of the following constants:
+.TP
+.B SPU_CREATE_EVENTS_ENABLED
+Rather than using signals for reporting DMA errors, use the
+.I event
+argument to
+.BR spu_run (2).
+.TP
+.B SPU_CREATE_GANG
+Create an SPU gang instead of a context.
+(A gang is a group of SPU contexts that are
+functionally related to each other and which share common scheduling
+parameters\[em]priority and policy.
+In the future, gang scheduling may be implemented causing
+the group to be switched in and out as a single unit.)
+.IP
+A new directory will be created at the location specified by the
+.I pathname
+argument.
+This gang may be used to hold other SPU contexts, by providing
+a pathname that is within the gang directory to further calls to
+.BR spu_create ().
+.TP
+.B SPU_CREATE_NOSCHED
+Create a context that is not affected by the SPU scheduler.
+Once the context is run,
+it will not be scheduled out until it is destroyed by
+the creating process.
+.IP
+Because the context cannot be removed from the SPU, some functionality
+is disabled for
+.B SPU_CREATE_NOSCHED
+contexts.
+Only a subset of the files will be
+available in this context directory in
+.BR spufs .
+Additionally,
+.B SPU_CREATE_NOSCHED
+contexts cannot dump a core file when crashing.
+.IP
+Creating
+.B SPU_CREATE_NOSCHED
+contexts requires the
+.B CAP_SYS_NICE
+capability.
+.TP
+.B SPU_CREATE_ISOLATE
+Create an isolated SPU context.
+Isolated contexts are protected from some
+PPE (PowerPC Processing Element)
+operations,
+such as access to the SPU local store and the NPC register.
+.IP
+Creating
+.B SPU_CREATE_ISOLATE
+contexts also requires the
+.B SPU_CREATE_NOSCHED
+flag.
+.TP
+.BR SPU_CREATE_AFFINITY_SPU " (since Linux 2.6.23)"
+.\" commit 8e68e2f248332a9c3fd4f08258f488c209bd3e0c
+Create a context with affinity to another SPU context.
+This affinity information is used within the SPU scheduling algorithm.
+Using this flag requires that a file descriptor referring to
+the other SPU context be passed in the
+.I neighbor_fd
+argument.
+.TP
+.BR SPU_CREATE_AFFINITY_MEM " (since Linux 2.6.23)"
+.\" commit 8e68e2f248332a9c3fd4f08258f488c209bd3e0c
+Create a context with affinity to system memory.
+This affinity information
+is used within the SPU scheduling algorithm.
+.SH RETURN VALUE
+On success,
+.BR spu_create ()
+returns a new file descriptor.
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The current user does not have write access to the
+.BR spufs (7)
+mount point.
+.TP
+.B EEXIST
+An SPU context already exists at the given pathname.
+.TP
+.B EFAULT
+.I pathname
+is not a valid string pointer in the
+calling process's address space.
+.TP
+.B EINVAL
+.I pathname
+is not a directory in the
+.BR spufs (7)
+mount point, or invalid flags have been provided.
+.TP
+.B ELOOP
+Too many symbolic links were found while resolving
+.IR pathname .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENODEV
+An isolated context was requested, but the hardware does not support
+SPU isolation.
+.TP
+.B ENOENT
+Part of
+.I pathname
+could not be resolved.
+.TP
+.B ENOMEM
+The kernel could not allocate all resources required.
+.TP
+.B ENOSPC
+There are not enough SPU resources available to create
+a new context or the user-specific limit for the number
+of SPU contexts has been reached.
+.TP
+.B ENOSYS
+The functionality is not provided by the current system, because
+either the hardware does not provide SPUs or the spufs module is not
+loaded.
+.TP
+.B ENOTDIR
+A part of
+.I pathname
+is not a directory.
+.TP
+.B EPERM
+The
+.B SPU_CREATE_NOSCHED
+flag has been given, but the user does not have the
+.B CAP_SYS_NICE
+capability.
+.SH FILES
+.I pathname
+must point to a location beneath the mount point of
+.BR spufs .
+By convention, it gets mounted in
+.IR /spu .
+.SH STANDARDS
+Linux on PowerPC.
+.SH HISTORY
+Linux 2.6.16.
+.P
+Prior to the addition of the
+.B SPU_CREATE_AFFINITY_SPU
+flag in Linux 2.6.23, the
+.BR spu_create ()
+system call took only three arguments (i.e., there was no
+.I neighbor_fd
+argument).
+.SH NOTES
+.BR spu_create ()
+is meant to be used from libraries that implement a more abstract
+interface to SPUs, not to be used from regular applications.
+See
+.UR http://www.bsc.es\:/projects\:/deepcomputing\:/linuxoncell/
+.UE
+for the recommended libraries.
+.SH EXAMPLES
+See
+.BR spu_run (2)
+for an example of the use of
+.BR spu_create ()
+.SH SEE ALSO
+.BR close (2),
+.BR spu_run (2),
+.BR capabilities (7),
+.BR spufs (7)
diff --git a/man/man2/spu_run.2 b/man/man2/spu_run.2
new file mode 100644
index 000000000..d96592726
--- /dev/null
+++ b/man/man2/spu_run.2
@@ -0,0 +1,260 @@
+.\" Copyright (c) International Business Machines Corp., 2006
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" HISTORY:
+.\" 2005-09-28, created by Arnd Bergmann <arndb@de.ibm.com>
+.\" 2006-06-16, revised by Eduardo M. Fleury <efleury@br.ibm.com>
+.\" 2007-07-10, some polishing by mtk
+.\" 2007-09-28, updates for newer kernels, added example
+.\"             by Jeremy Kerr <jk@ozlabs.org>
+.\"
+.TH spu_run 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+spu_run \- execute an SPU context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/spu.h>" "          /* Definition of " SPU_* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_spu_run, int " fd ", uint32_t *" npc \
+", uint32_t *" event );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR spu_run (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The
+.BR spu_run ()
+system call is used on PowerPC machines that implement the
+Cell Broadband Engine Architecture in order to access Synergistic
+Processor Units (SPUs).
+The
+.I fd
+argument is a file descriptor returned by
+.BR spu_create (2)
+that refers to a specific SPU context.
+When the context gets scheduled to a physical SPU,
+it starts execution at the instruction pointer passed in
+.IR npc .
+.P
+Execution of SPU code happens synchronously, meaning that
+.BR spu_run ()
+blocks while the SPU is still running.
+If there is a need
+to execute SPU code in parallel with other code on either the
+main CPU or other SPUs, a new thread of execution must be created
+first (e.g., using
+.BR pthread_create (3)).
+.P
+When
+.BR spu_run ()
+returns, the current value of the SPU program counter is written to
+.IR npc ,
+so successive calls to
+.BR spu_run ()
+can use the same
+.I npc
+pointer.
+.P
+The
+.I event
+argument provides a buffer for an extended status code.
+If the SPU
+context was created with the
+.B SPU_CREATE_EVENTS_ENABLED
+flag, then this buffer is populated by the Linux kernel before
+.BR spu_run ()
+returns.
+.P
+The status code may be one (or more) of the following constants:
+.TP
+.B SPE_EVENT_DMA_ALIGNMENT
+A DMA alignment error occurred.
+.TP
+.B SPE_EVENT_INVALID_DMA
+An invalid MFC DMA command was attempted.
+.\" SPE_EVENT_SPE_DATA_SEGMENT is defined, but does not seem to be generated
+.\" at any point (in Linux 5.9 sources).
+.TP
+.B SPE_EVENT_SPE_DATA_STORAGE
+A DMA storage error occurred.
+.TP
+.B SPE_EVENT_SPE_ERROR
+An illegal instruction was executed.
+.P
+NULL
+is a valid value for the
+.I event
+argument.
+In this case, the events will not be reported to the calling process.
+.SH RETURN VALUE
+On success,
+.BR spu_run ()
+returns the value of the
+.I spu_status
+register.
+On failure, it returns \-1 and sets
+.I errno
+is set to indicate the error.
+.P
+The
+.I spu_status
+register value is a bit mask of status codes and
+optionally a 14-bit code returned from the
+.B stop-and-signal
+instruction on the SPU.
+The bit masks for the status codes
+are:
+.TP
+.B 0x02
+SPU was stopped by a
+.B stop-and-signal
+instruction.
+.TP
+.B 0x04
+SPU was stopped by a
+.B halt
+instruction.
+.TP
+.B 0x08
+SPU is waiting for a channel.
+.TP
+.B 0x10
+SPU is in single-step mode.
+.TP
+.B 0x20
+SPU has tried to execute an invalid instruction.
+.TP
+.B 0x40
+SPU has tried to access an invalid channel.
+.TP
+.B 0x3fff0000
+The bits masked with this value contain the code returned from a
+.B stop-and-signal
+instruction.
+These bits are valid only if the 0x02 bit is set.
+.P
+If
+.BR spu_run ()
+has not returned an error, one or more bits among the lower eight
+ones are always set.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+.I npc
+is not a valid pointer, or
+.I event
+is non-NULL and an invalid pointer.
+.TP
+.B EINTR
+A signal occurred while
+.BR spu_run ()
+was in progress; see
+.BR signal (7).
+The
+.I npc
+value has been updated to the new program counter value if
+necessary.
+.TP
+.B EINVAL
+.I fd
+is not a valid file descriptor returned from
+.BR spu_create (2).
+.TP
+.B ENOMEM
+There was not enough memory available to handle a page fault
+resulting from a Memory Flow Controller (MFC) direct memory access.
+.TP
+.B ENOSYS
+The functionality is not provided by the current system, because
+either the hardware does not provide SPUs or the spufs module is not
+loaded.
+.SH STANDARDS
+Linux on PowerPC.
+.SH HISTORY
+Linux 2.6.16.
+.SH NOTES
+.BR spu_run ()
+is meant to be used from libraries that implement a more abstract
+interface to SPUs, not to be used from regular applications.
+See
+.UR http://www.bsc.es\:/projects\:/deepcomputing\:/linuxoncell/
+.UE
+for the recommended libraries.
+.SH EXAMPLES
+The following is an example of running a simple, one-instruction SPU
+program with the
+.BR spu_run ()
+system call.
+.P
+.\" SRC BEGIN (spu_run.c)
+.EX
+#include <err.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+\&
+int main(void)
+{
+    int       context, fd, spu_status;
+    uint32_t  instruction, npc;
+\&
+    context = syscall(SYS_spu_create, "/spu/example\-context", 0, 0755);
+    if (context == \-1)
+        err(EXIT_FAILURE, "spu_create");
+\&
+    /*
+     * Write a \[aq]stop 0x1234\[aq] instruction to the SPU\[aq]s
+     * local store memory.
+     */
+    instruction = 0x00001234;
+\&
+    fd = open("/spu/example\-context/mem", O_RDWR);
+    if (fd == \-1)
+        err(EXIT_FAILURE, "open");
+    write(fd, &instruction, sizeof(instruction));
+\&
+    /*
+     * set npc to the starting instruction address of the
+     * SPU program. Since we wrote the instruction at the
+     * start of the mem file, the entry point will be 0x0.
+     */
+    npc = 0;
+\&
+    spu_status = syscall(SYS_spu_run, context, &npc, NULL);
+    if (spu_status == \-1)
+        err(EXIT_FAILURE, "open");
+\&
+    /*
+     * We should see a status code of 0x12340002:
+     *   0x00000002 (spu was stopped due to stop\-and\-signal)
+     * | 0x12340000 (the stop\-and\-signal code)
+     */
+    printf("SPU Status: %#08x\en", spu_status);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.\" .SH AUTHORS
+.\" Arnd Bergmann <arndb@de.ibm.com>, Jeremy Kerr <jk@ozlabs.org>
+.SH SEE ALSO
+.BR close (2),
+.BR spu_create (2),
+.BR capabilities (7),
+.BR spufs (7)
diff --git a/man/man2/ssetmask.2 b/man/man2/ssetmask.2
new file mode 100644
index 000000000..a7f99d206
--- /dev/null
+++ b/man/man2/ssetmask.2
@@ -0,0 +1 @@
+.so man2/sgetmask.2
diff --git a/man/man2/stat.2 b/man/man2/stat.2
new file mode 100644
index 000000000..e15269a70
--- /dev/null
+++ b/man/man2/stat.2
@@ -0,0 +1,539 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\" Parts Copyright (c) 1995 Nicolai Langfeldt (janl@ifi.uio.no), 1/1/95
+.\" and Copyright (c) 2006, 2007, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-05-18 by Todd Larason <jtl@molehill.org>
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1995-01-09 by Richard Kettlewell <richard@greenend.org.uk>
+.\" Modified 1998-05-13 by Michael Haardt <michael@cantor.informatik.rwth-aachen.de>
+.\" Modified 1999-07-06 by aeb & Albert Cahalan
+.\" Modified 2000-01-07 by aeb
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 2007-06-08 mtk: Added example program
+.\" 2007-07-05 mtk: Added details on underlying system call interfaces
+.\"
+.TH stat 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stat, fstat, lstat, fstatat \- get file status
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/stat.h>
+.P
+.BI "int stat(const char *restrict " pathname ,
+.BI "         struct stat *restrict " statbuf );
+.BI "int fstat(int " fd ", struct stat *" statbuf );
+.BI "int lstat(const char *restrict " pathname ,
+.BI "         struct stat *restrict " statbuf );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of " AT_* " constants */"
+.B #include <sys/stat.h>
+.P
+.BI "int fstatat(int " dirfd ", const char *restrict " pathname ,
+.BI "         struct stat *restrict " statbuf ", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR lstat ():
+.nf
+    /* Since glibc 2.20 */ _DEFAULT_SOURCE
+        || _XOPEN_SOURCE >= 500
+.\"   _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L
+        || /* glibc 2.19 and earlier */ _BSD_SOURCE
+.fi
+.P
+.BR fstatat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return information about a file, in the buffer pointed to by
+.IR statbuf .
+No permissions are required on the file itself, but\[em]in the case of
+.BR stat (),
+.BR fstatat (),
+and
+.BR lstat ()\[em]execute
+(search) permission is required on all of the directories in
+.I pathname
+that lead to the file.
+.P
+.BR stat ()
+and
+.BR fstatat ()
+retrieve information about the file pointed to by
+.IR pathname ;
+the differences for
+.BR fstatat ()
+are described below.
+.P
+.BR lstat ()
+is identical to
+.BR stat (),
+except that if
+.I pathname
+is a symbolic link, then it returns information about the link itself,
+not the file that the link refers to.
+.P
+.BR fstat ()
+is identical to
+.BR stat (),
+except that the file about which information is to be retrieved
+is specified by the file descriptor
+.IR fd .
+.\"
+.SS The stat structure
+All of these system calls return a
+.I stat
+structure (see
+.BR stat (3type)).
+.P
+.\" Background: inode attributes are modified with i_mutex held, but
+.\" read by stat() without taking the mutex.
+.IR Note :
+for performance and simplicity reasons, different fields in the
+.I stat
+structure may contain state information from different moments
+during the execution of the system call.
+For example, if
+.I st_mode
+or
+.I st_uid
+is changed by another process by calling
+.BR chmod (2)
+or
+.BR chown (2),
+.BR stat ()
+might return the old
+.I st_mode
+together with the new
+.IR st_uid ,
+or the old
+.I st_uid
+together with the new
+.IR st_mode .
+.SS fstatat()
+The
+.BR fstatat ()
+system call is a more general interface for accessing file information
+which can still provide exactly the behavior of each of
+.BR stat (),
+.BR lstat (),
+and
+.BR fstat ().
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR stat ()
+and
+.BR lstat ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR stat ()
+and
+.BR lstat ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+.I flags
+can either be 0, or include one or more of the following flags ORed:
+.TP
+.BR AT_EMPTY_PATH " (since Linux 2.6.39)"
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.I dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+In this case,
+.I dirfd
+can refer to any type of file, not just a directory, and
+the behavior of
+.BR fstatat ()
+is similar to that of
+.BR fstat ().
+If
+.I dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed
+to obtain its definition.
+.TP
+.BR AT_NO_AUTOMOUNT " (since Linux 2.6.38)"
+Don't automount the terminal ("basename") component of
+.I pathname.
+Since Linux 3.1 this flag is ignored.
+Since Linux 4.11 this flag is implied.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+is a symbolic link, do not dereference it:
+instead return information about the link itself, like
+.BR lstat ().
+(By default,
+.BR fstatat ()
+dereferences symbolic links, like
+.BR stat ().)
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR fstatat ().
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission is denied for one of the directories
+in the path prefix of
+.IR pathname .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.I fd
+is not a valid open file descriptor.
+.TP
+.B EBADF
+.RB ( fstatat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+Bad address.
+.TP
+.B EINVAL
+.RB ( fstatat ())
+Invalid flag specified in
+.IR flags .
+.TP
+.B ELOOP
+Too many symbolic links encountered while traversing the path.
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+A component of
+.I pathname
+does not exist or is a dangling symbolic link.
+.TP
+.B ENOENT
+.I pathname
+is an empty string and
+.B AT_EMPTY_PATH
+was not specified in
+.IR flags .
+.TP
+.B ENOMEM
+Out of memory (i.e., kernel memory).
+.TP
+.B ENOTDIR
+A component of the path prefix of
+.I pathname
+is not a directory.
+.TP
+.B ENOTDIR
+.RB ( fstatat ())
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EOVERFLOW
+.I pathname
+or
+.I fd
+refers to a file whose size, inode number,
+or number of blocks cannot be represented in, respectively, the types
+.IR off_t ,
+.IR ino_t ,
+or
+.IR blkcnt_t .
+This error can occur when, for example,
+an application compiled on a 32-bit platform without
+.I \-D_FILE_OFFSET_BITS=64
+calls
+.BR stat ()
+on a file whose size exceeds
+.I (1<<31)\-1
+bytes.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR stat ()
+.TQ
+.BR fstat ()
+.TQ
+.BR lstat ()
+SVr4, 4.3BSD, POSIX.1-2001.
+.\" SVr4 documents additional
+.\" .BR fstat ()
+.\" error conditions EINTR, ENOLINK, and EOVERFLOW.  SVr4
+.\" documents additional
+.\" .BR stat ()
+.\" and
+.\" .BR lstat ()
+.\" error conditions EINTR, EMULTIHOP, ENOLINK, and EOVERFLOW.
+.TP
+.BR fstatat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.P
+According to POSIX.1-2001,
+.BR lstat ()
+on a symbolic link need return valid information only in the
+.I st_size
+field and the file type of the
+.I st_mode
+field of the
+.I stat
+structure.
+POSIX.1-2008 tightens the specification, requiring
+.BR lstat ()
+to return valid information in all fields except the mode bits in
+.IR st_mode .
+.P
+Use of the
+.I st_blocks
+and
+.I st_blksize
+fields may be less portable.
+(They were introduced in BSD.
+The interpretation differs between systems,
+and possibly on a single system when NFS mounts are involved.)
+.SS C library/kernel differences
+Over time, increases in the size of the
+.I stat
+structure have led to three successive versions of
+.BR stat ():
+.IR sys_stat ()
+(slot
+.IR __NR_oldstat ),
+.IR sys_newstat ()
+(slot
+.IR __NR_stat ),
+and
+.I sys_stat64()
+(slot
+.IR __NR_stat64 )
+on 32-bit platforms such as i386.
+The first two versions were already present in Linux 1.0
+(albeit with different names);
+.\" See include/asm-i386/stat.h in the Linux 2.4 source code for the
+.\" various versions of the structure definitions
+the last was added in Linux 2.4.
+Similar remarks apply for
+.BR fstat ()
+and
+.BR lstat ().
+.P
+The kernel-internal versions of the
+.I stat
+structure dealt with by the different versions are, respectively:
+.TP
+.I __old_kernel_stat
+The original structure, with rather narrow fields, and no padding.
+.TP
+.I stat
+Larger
+.I st_ino
+field and padding added to various parts of the structure to
+allow for future expansion.
+.TP
+.I stat64
+Even larger
+.I st_ino
+field,
+larger
+.I st_uid
+and
+.I st_gid
+fields to accommodate the Linux-2.4 expansion of UIDs and GIDs to 32 bits,
+and various other enlarged fields and further padding in the structure.
+(Various padding bytes were eventually consumed in Linux 2.6,
+with the advent of 32-bit device IDs and nanosecond components
+for the timestamp fields.)
+.P
+The glibc
+.BR stat ()
+wrapper function hides these details from applications,
+invoking the most recent version of the system call provided by the kernel,
+and repacking the returned information if required for old binaries.
+.\"
+.\" A note from Andries Brouwer, July 2007
+.\"
+.\" > Is the story not rather more complicated for some calls like
+.\" > stat(2)?
+.\"
+.\" Yes and no, mostly no. See /usr/include/sys/stat.h .
+.\"
+.\" The idea is here not so much that syscalls change, but that
+.\" the definitions of struct stat and of the types dev_t and mode_t change.
+.\" This means that libc (even if it does not call the kernel
+.\" but only calls some internal function) must know what the
+.\" format of dev_t or of struct stat is.
+.\" The communication between the application and libc goes via
+.\" the include file <sys/stat.h> that defines a _STAT_VER and
+.\" _MKNOD_VER describing the layout of the data that user space
+.\" uses. Each (almost each) occurrence of stat() is replaced by
+.\" an occurrence of xstat() where the first parameter of xstat()
+.\" is this version number _STAT_VER.
+.\"
+.\" Now, also the definitions used by the kernel change.
+.\" But glibc copes with this in the standard way, and the
+.\" struct stat as returned by the kernel is repacked into
+.\" the struct stat as expected by the application.
+.\" Thus, _STAT_VER and this setup cater for the application-libc
+.\" interface, rather than the libc-kernel interface.
+.\"
+.\" (Note that the details depend on gcc being used as c compiler.)
+.P
+On modern 64-bit systems, life is simpler: there is a single
+.BR stat ()
+system call and the kernel deals with a
+.I stat
+structure that contains fields of a sufficient size.
+.P
+The underlying system call employed by the glibc
+.BR fstatat ()
+wrapper function is actually called
+.BR fstatat64 ()
+or, on some architectures,
+.\" strace(1) shows the name "newfstatat" on x86-64
+.BR newfstatat ().
+.SH EXAMPLES
+The following program calls
+.BR lstat ()
+and displays selected fields in the returned
+.I stat
+structure.
+.P
+.\" SRC BEGIN (stat.c)
+.EX
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <time.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    struct stat sb;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <pathname>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (lstat(argv[1], &sb) == \-1) {
+        perror("lstat");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("ID of containing device:  [%x,%x]\en",
+           major(sb.st_dev),
+           minor(sb.st_dev));
+\&
+    printf("File type:                ");
+\&
+    switch (sb.st_mode & S_IFMT) {
+    case S_IFBLK:  printf("block device\en");            break;
+    case S_IFCHR:  printf("character device\en");        break;
+    case S_IFDIR:  printf("directory\en");               break;
+    case S_IFIFO:  printf("FIFO/pipe\en");               break;
+    case S_IFLNK:  printf("symlink\en");                 break;
+    case S_IFREG:  printf("regular file\en");            break;
+    case S_IFSOCK: printf("socket\en");                  break;
+    default:       printf("unknown?\en");                break;
+    }
+\&
+    printf("I\-node number:            %ju\en", (uintmax_t) sb.st_ino);
+\&
+    printf("Mode:                     %jo (octal)\en",
+           (uintmax_t) sb.st_mode);
+\&
+    printf("Link count:               %ju\en", (uintmax_t) sb.st_nlink);
+    printf("Ownership:                UID=%ju   GID=%ju\en",
+           (uintmax_t) sb.st_uid, (uintmax_t) sb.st_gid);
+\&
+    printf("Preferred I/O block size: %jd bytes\en",
+           (intmax_t) sb.st_blksize);
+    printf("File size:                %jd bytes\en",
+           (intmax_t) sb.st_size);
+    printf("Blocks allocated:         %jd\en",
+           (intmax_t) sb.st_blocks);
+\&
+    printf("Last status change:       %s", ctime(&sb.st_ctime));
+    printf("Last file access:         %s", ctime(&sb.st_atime));
+    printf("Last file modification:   %s", ctime(&sb.st_mtime));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ls (1),
+.BR stat (1),
+.BR access (2),
+.BR chmod (2),
+.BR chown (2),
+.BR readlink (2),
+.BR statx (2),
+.BR utime (2),
+.BR stat (3type),
+.BR capabilities (7),
+.BR inode (7),
+.BR symlink (7)
diff --git a/man/man2/stat64.2 b/man/man2/stat64.2
new file mode 100644
index 000000000..b1a86c195
--- /dev/null
+++ b/man/man2/stat64.2
@@ -0,0 +1 @@
+.so man2/stat.2
diff --git a/man/man2/statfs.2 b/man/man2/statfs.2
new file mode 100644
index 000000000..ffee7ee87
--- /dev/null
+++ b/man/man2/statfs.2
@@ -0,0 +1,389 @@
+.\" Copyright (C) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 2003-08-17 by Walter Harms
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH statfs 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+statfs, fstatfs \- get filesystem statistics
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/vfs.h>    " "/* or <sys/statfs.h> */"
+.P
+.BI "int statfs(const char *" path ", struct statfs *" buf );
+.BI "int fstatfs(int " fd ", struct statfs *" buf );
+.fi
+.P
+Unless you need the
+.I f_type
+field, you should use the standard
+.BR statvfs (3)
+interface instead.
+.SH DESCRIPTION
+The
+.BR statfs ()
+system call returns information about a mounted filesystem.
+.I path
+is the pathname of any file within the mounted filesystem.
+.I buf
+is a pointer to a
+.I statfs
+structure defined approximately as follows:
+.P
+.in +4n
+.EX
+struct statfs {
+    __fsword_t f_type;    /* Type of filesystem (see below) */
+    __fsword_t f_bsize;   /* Optimal transfer block size */
+    fsblkcnt_t f_blocks;  /* Total data blocks in filesystem */
+    fsblkcnt_t f_bfree;   /* Free blocks in filesystem */
+    fsblkcnt_t f_bavail;  /* Free blocks available to
+                             unprivileged user */
+    fsfilcnt_t f_files;   /* Total inodes in filesystem */
+    fsfilcnt_t f_ffree;   /* Free inodes in filesystem */
+    fsid_t     f_fsid;    /* Filesystem ID */
+    __fsword_t f_namelen; /* Maximum length of filenames */
+    __fsword_t f_frsize;  /* Fragment size (since Linux 2.6) */
+    __fsword_t f_flags;   /* Mount flags of filesystem
+                             (since Linux 2.6.36) */
+    __fsword_t f_spare[xxx];
+                    /* Padding bytes reserved for future use */
+};
+.EE
+.in
+.P
+The following filesystem types may appear in
+.IR f_type :
+.P
+.in +4n
+.EX
+ADFS_SUPER_MAGIC      0xadf5
+AFFS_SUPER_MAGIC      0xadff
+AFS_SUPER_MAGIC       0x5346414f
+ANON_INODE_FS_MAGIC   0x09041934 /* Anonymous inode FS (for
+                                    pseudofiles that have no name;
+                                    e.g., epoll, signalfd, bpf) */
+AUTOFS_SUPER_MAGIC    0x0187
+BDEVFS_MAGIC          0x62646576
+BEFS_SUPER_MAGIC      0x42465331
+BFS_MAGIC             0x1badface
+BINFMTFS_MAGIC        0x42494e4d
+BPF_FS_MAGIC          0xcafe4a11
+BTRFS_SUPER_MAGIC     0x9123683e
+BTRFS_TEST_MAGIC      0x73727279
+CGROUP_SUPER_MAGIC    0x27e0eb   /* Cgroup pseudo FS */
+CGROUP2_SUPER_MAGIC   0x63677270 /* Cgroup v2 pseudo FS */
+CIFS_MAGIC_NUMBER     0xff534d42
+CODA_SUPER_MAGIC      0x73757245
+COH_SUPER_MAGIC       0x012ff7b7
+CRAMFS_MAGIC          0x28cd3d45
+DEBUGFS_MAGIC         0x64626720
+DEVFS_SUPER_MAGIC     0x1373     /* Linux 2.6.17 and earlier */
+DEVPTS_SUPER_MAGIC    0x1cd1
+ECRYPTFS_SUPER_MAGIC  0xf15f
+EFIVARFS_MAGIC        0xde5e81e4
+EFS_SUPER_MAGIC       0x00414a53
+EXT_SUPER_MAGIC       0x137d     /* Linux 2.0 and earlier */
+EXT2_OLD_SUPER_MAGIC  0xef51
+EXT2_SUPER_MAGIC      0xef53
+EXT3_SUPER_MAGIC      0xef53
+EXT4_SUPER_MAGIC      0xef53
+F2FS_SUPER_MAGIC      0xf2f52010
+FUSE_SUPER_MAGIC      0x65735546
+FUTEXFS_SUPER_MAGIC   0xbad1dea  /* Unused */
+HFS_SUPER_MAGIC       0x4244
+HOSTFS_SUPER_MAGIC    0x00c0ffee
+HPFS_SUPER_MAGIC      0xf995e849
+HUGETLBFS_MAGIC       0x958458f6
+ISOFS_SUPER_MAGIC     0x9660
+JFFS2_SUPER_MAGIC     0x72b6
+JFS_SUPER_MAGIC       0x3153464a
+MINIX_SUPER_MAGIC     0x137f     /* original minix FS */
+MINIX_SUPER_MAGIC2    0x138f     /* 30 char minix FS */
+MINIX2_SUPER_MAGIC    0x2468     /* minix V2 FS */
+MINIX2_SUPER_MAGIC2   0x2478     /* minix V2 FS, 30 char names */
+MINIX3_SUPER_MAGIC    0x4d5a     /* minix V3 FS, 60 char names */
+MQUEUE_MAGIC          0x19800202 /* POSIX message queue FS */
+MSDOS_SUPER_MAGIC     0x4d44
+MTD_INODE_FS_MAGIC    0x11307854
+NCP_SUPER_MAGIC       0x564c
+NFS_SUPER_MAGIC       0x6969
+NILFS_SUPER_MAGIC     0x3434
+NSFS_MAGIC            0x6e736673
+NTFS_SB_MAGIC         0x5346544e
+OCFS2_SUPER_MAGIC     0x7461636f
+OPENPROM_SUPER_MAGIC  0x9fa1
+OVERLAYFS_SUPER_MAGIC 0x794c7630
+PIPEFS_MAGIC          0x50495045
+PROC_SUPER_MAGIC      0x9fa0     /* /proc FS */
+PSTOREFS_MAGIC        0x6165676c
+QNX4_SUPER_MAGIC      0x002f
+QNX6_SUPER_MAGIC      0x68191122
+RAMFS_MAGIC           0x858458f6
+REISERFS_SUPER_MAGIC  0x52654973
+ROMFS_MAGIC           0x7275
+SECURITYFS_MAGIC      0x73636673
+SELINUX_MAGIC         0xf97cff8c
+SMACK_MAGIC           0x43415d53
+SMB_SUPER_MAGIC       0x517b
+SMB2_MAGIC_NUMBER     0xfe534d42
+SOCKFS_MAGIC          0x534f434b
+SQUASHFS_MAGIC        0x73717368
+SYSFS_MAGIC           0x62656572
+SYSV2_SUPER_MAGIC     0x012ff7b6
+SYSV4_SUPER_MAGIC     0x012ff7b5
+TMPFS_MAGIC           0x01021994
+TRACEFS_MAGIC         0x74726163
+UDF_SUPER_MAGIC       0x15013346
+UFS_MAGIC             0x00011954
+USBDEVICE_SUPER_MAGIC 0x9fa2
+V9FS_MAGIC            0x01021997
+VXFS_SUPER_MAGIC      0xa501fcf5
+XENFS_SUPER_MAGIC     0xabba1974
+XENIX_SUPER_MAGIC     0x012ff7b4
+XFS_SUPER_MAGIC       0x58465342
+_XIAFS_SUPER_MAGIC    0x012fd16d /* Linux 2.0 and earlier */
+.EE
+.in
+.P
+Most of these MAGIC constants are defined in
+.IR /usr/include/linux/magic.h ,
+and some are hardcoded in kernel sources.
+.P
+The
+.I f_flags
+field is a bit mask indicating mount options for the filesystem.
+It contains zero or more of the following bits:
+.\" XXX Keep this list in sync with statvfs(3)
+.TP
+.B ST_MANDLOCK
+Mandatory locking is permitted on the filesystem (see
+.BR fcntl (2)).
+.TP
+.B ST_NOATIME
+Do not update access times; see
+.BR mount (2).
+.TP
+.B ST_NODEV
+Disallow access to device special files on this filesystem.
+.TP
+.B ST_NODIRATIME
+Do not update directory access times; see
+.BR mount (2).
+.TP
+.B ST_NOEXEC
+Execution of programs is disallowed on this filesystem.
+.TP
+.B ST_NOSUID
+The set-user-ID and set-group-ID bits are ignored by
+.BR exec (3)
+for executable files on this filesystem
+.TP
+.B ST_RDONLY
+This filesystem is mounted read-only.
+.TP
+.B ST_RELATIME
+Update atime relative to mtime/ctime; see
+.BR mount (2).
+.TP
+.B ST_SYNCHRONOUS
+Writes are synched to the filesystem immediately (see the description of
+.B O_SYNC
+in
+.BR open (2)).
+.TP
+.BR ST_NOSYMFOLLOW " (since Linux 5.10)"
+.\" dab741e0e02bd3c4f5e2e97be74b39df2523fc6e
+Symbolic links are not followed when resolving paths; see
+.BR mount (2).
+.P
+Nobody knows what
+.I f_fsid
+is supposed to contain (but see below).
+.P
+Fields that are undefined for a particular filesystem are set to 0.
+.P
+.BR fstatfs ()
+returns the same information about an open file referenced by descriptor
+.IR fd .
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.RB ( statfs ())
+Search permission is denied for a component of the path prefix of
+.IR path .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( fstatfs ())
+.I fd
+is not a valid open file descriptor.
+.TP
+.B EFAULT
+.I buf
+or
+.I path
+points to an invalid address.
+.TP
+.B EINTR
+The call was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EIO
+An I/O error occurred while reading from the filesystem.
+.TP
+.B ELOOP
+.RB ( statfs ())
+Too many symbolic links were encountered in translating
+.IR path .
+.TP
+.B ENAMETOOLONG
+.RB ( statfs ())
+.I path
+is too long.
+.TP
+.B ENOENT
+.RB ( statfs ())
+The file referred to by
+.I path
+does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSYS
+The filesystem does not support this call.
+.TP
+.B ENOTDIR
+.RB ( statfs ())
+A component of the path prefix of
+.I path
+is not a directory.
+.TP
+.B EOVERFLOW
+Some values were too large to be represented in the returned struct.
+.SH VERSIONS
+.SS The f_fsid field
+Solaris, Irix, and POSIX have a system call
+.BR statvfs (2)
+that returns a
+.I "struct statvfs"
+(defined in
+.IR <sys/statvfs.h> )
+containing an
+.I "unsigned long"
+.IR f_fsid .
+Linux, SunOS, HP-UX, 4.4BSD have a system call
+.BR statfs ()
+that returns a
+.I "struct statfs"
+(defined in
+.IR <sys/vfs.h> )
+containing a
+.I fsid_t
+.IR f_fsid ,
+where
+.I fsid_t
+is defined as
+.IR "struct { int val[2]; }" .
+The same holds for FreeBSD, except that it uses the include file
+.IR <sys/mount.h> .
+.P
+The general idea is that
+.I f_fsid
+contains some random stuff such that the pair
+.RI ( f_fsid , ino )
+uniquely determines a file.
+Some operating systems use (a variation on) the device number,
+or the device number combined with the filesystem type.
+Several operating systems restrict giving out the
+.I f_fsid
+field to the superuser only (and zero it for unprivileged users),
+because this field is used in the filehandle of the filesystem
+when NFS-exported, and giving it out is a security concern.
+.P
+Under some operating systems, the
+.I fsid
+can be used as the second argument to the
+.BR sysfs (2)
+system call.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+The Linux
+.BR statfs ()
+was inspired by the 4.4BSD one
+(but they do not use the same structure).
+.P
+The original Linux
+.BR statfs ()
+and
+.BR fstatfs ()
+system calls were not designed with extremely large file sizes in mind.
+Subsequently, Linux 2.6
+added new
+.BR statfs64 ()
+and
+.BR fstatfs64 ()
+system calls that employ a new structure,
+.IR statfs64 .
+The new structure contains the same fields as the original
+.I statfs
+structure, but the sizes of various fields are increased,
+to accommodate large file sizes.
+The glibc
+.BR statfs ()
+and
+.BR fstatfs ()
+wrapper functions transparently deal with the kernel differences.
+.P
+LSB has deprecated the library calls
+.BR statfs ()
+and
+.BR fstatfs ()
+and tells us to use
+.BR statvfs (3)
+and
+.BR fstatvfs (3)
+instead.
+.SH NOTES
+The
+.I __fsword_t
+type used for various fields in the
+.I statfs
+structure definition is a glibc internal type,
+not intended for public use.
+This leaves the programmer in a bit of a conundrum when trying to copy
+or compare these fields to local variables in a program.
+Using
+.I "unsigned\ int"
+for such variables suffices on most systems.
+.P
+Some systems have only \fI<sys/vfs.h>\fP, other systems also have
+\fI<sys/statfs.h>\fP, where the former includes the latter.
+So it seems
+including the former is the best choice.
+.SH BUGS
+From Linux 2.6.38 up to and including Linux 3.1,
+.\" broken in commit ff0c7d15f9787b7e8c601533c015295cc68329f8
+.\" fixed in commit d70ef97baf048412c395bb5d65791d8fe133a52b
+.BR fstatfs ()
+failed with the error
+.B ENOSYS
+for file descriptors created by
+.BR pipe (2).
+.SH SEE ALSO
+.BR stat (2),
+.BR statvfs (3),
+.BR path_resolution (7)
diff --git a/man/man2/statfs64.2 b/man/man2/statfs64.2
new file mode 100644
index 000000000..923d3c0cc
--- /dev/null
+++ b/man/man2/statfs64.2
@@ -0,0 +1 @@
+.so man2/statfs.2
diff --git a/man/man2/statx.2 b/man/man2/statx.2
new file mode 100644
index 000000000..0dcf7e20b
--- /dev/null
+++ b/man/man2/statx.2
@@ -0,0 +1,614 @@
+'\" t
+.\" Copyright (c) 2017 David Howells <dhowells@redhat.com>
+.\"
+.\" Derived from the stat.2 manual page:
+.\"   Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"   Parts Copyright (c) 1995 Nicolai Langfeldt (janl@ifi.uio.no), 1/1/95
+.\"   and Copyright (c) 2006, 2007, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH statx 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+statx \- get file status (extended)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE          " "/* See feature_test_macros(7) */"
+.BR "#include <fcntl.h>           " "/* Definition of " AT_* " constants */"
+.B #include <sys/stat.h>
+.P
+.BI "int statx(int " dirfd ", const char *restrict " pathname ", int " flags ,
+.BI "          unsigned int " mask ", struct statx *restrict " statxbuf );
+.fi
+.SH DESCRIPTION
+This function returns information about a file, storing it in the buffer
+pointed to by
+.IR statxbuf .
+The returned buffer is a structure of the following type:
+.P
+.in +4n
+.EX
+struct statx {
+    __u32 stx_mask;        /* Mask of bits indicating
+                              filled fields */
+    __u32 stx_blksize;     /* Block size for filesystem I/O */
+    __u64 stx_attributes;  /* Extra file attribute indicators */
+    __u32 stx_nlink;       /* Number of hard links */
+    __u32 stx_uid;         /* User ID of owner */
+    __u32 stx_gid;         /* Group ID of owner */
+    __u16 stx_mode;        /* File type and mode */
+    __u64 stx_ino;         /* Inode number */
+    __u64 stx_size;        /* Total size in bytes */
+    __u64 stx_blocks;      /* Number of 512B blocks allocated */
+    __u64 stx_attributes_mask;
+                           /* Mask to show what\[aq]s supported
+                              in stx_attributes */
+\&
+    /* The following fields are file timestamps */
+    struct statx_timestamp stx_atime;  /* Last access */
+    struct statx_timestamp stx_btime;  /* Creation */
+    struct statx_timestamp stx_ctime;  /* Last status change */
+    struct statx_timestamp stx_mtime;  /* Last modification */
+\&
+    /* If this file represents a device, then the next two
+       fields contain the ID of the device */
+    __u32 stx_rdev_major;  /* Major ID */
+    __u32 stx_rdev_minor;  /* Minor ID */
+\&
+    /* The next two fields contain the ID of the device
+       containing the filesystem where the file resides */
+    __u32 stx_dev_major;   /* Major ID */
+    __u32 stx_dev_minor;   /* Minor ID */
+\&
+    __u64 stx_mnt_id;      /* Mount ID */
+\&
+    /* Direct I/O alignment restrictions */
+    __u32 stx_dio_mem_align;
+    __u32 stx_dio_offset_align;
+};
+.EE
+.in
+.P
+The file timestamps are structures of the following type:
+.P
+.in +4n
+.EX
+struct statx_timestamp {
+    __s64 tv_sec;    /* Seconds since the Epoch (UNIX time) */
+    __u32 tv_nsec;   /* Nanoseconds since tv_sec */
+};
+.EE
+.in
+.P
+(Note that reserved space and padding is omitted.)
+.SS
+Invoking \fBstatx\fR():
+To access a file's status, no permissions are required on the file itself,
+but in the case of
+.BR statx ()
+with a pathname,
+execute (search) permission is required on all of the directories in
+.I pathname
+that lead to the file.
+.P
+.BR statx ()
+uses
+.IR pathname ,
+.IR dirfd ,
+and
+.I flags
+to identify the target file in one of the following ways:
+.TP
+An absolute pathname
+If
+.I pathname
+begins with a slash,
+then it is an absolute pathname that identifies the target file.
+In this case,
+.I dirfd
+is ignored.
+.TP
+A relative pathname
+If
+.I pathname
+is a string that begins with a character other than a slash and
+.I dirfd
+is
+.BR AT_FDCWD ,
+then
+.I pathname
+is a relative pathname that is interpreted relative to the process's
+current working directory.
+.TP
+A directory-relative pathname
+If
+.I pathname
+is a string that begins with a character other than a slash and
+.I dirfd
+is a file descriptor that refers to a directory, then
+.I pathname
+is a relative pathname that is interpreted relative to the directory
+referred to by
+.IR dirfd .
+(See
+.BR openat (2)
+for an explanation of why this is useful.)
+.TP
+By file descriptor
+If
+.I pathname
+is an empty string and the
+.B AT_EMPTY_PATH
+flag is specified in
+.I flags
+(see below),
+then the target file is the one referred to by the file descriptor
+.IR dirfd .
+.P
+.I flags
+can be used to influence a pathname-based lookup.
+A value for
+.I flags
+is constructed by ORing together zero or more of the following constants:
+.TP
+.B AT_EMPTY_PATH
+.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.I dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+In this case,
+.I dirfd
+can refer to any type of file, not just a directory.
+.IP
+If
+.I dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+.TP
+.B AT_NO_AUTOMOUNT
+Don't automount the terminal ("basename") component of
+.I pathname
+if it is a directory that is an automount point.
+This allows the caller to gather attributes of an automount point
+(rather than the location it would mount).
+This flag has no effect if the mount point has already been mounted over.
+.IP
+The
+.B AT_NO_AUTOMOUNT
+flag can be used in tools that scan directories
+to prevent mass-automounting of a directory of automount points.
+.IP
+All of
+.BR stat (2),
+.BR lstat (2),
+and
+.BR fstatat (2)
+act as though
+.B AT_NO_AUTOMOUNT
+was set.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+is a symbolic link, do not dereference it:
+instead return information about the link itself, like
+.BR lstat (2).
+.P
+.I flags
+can also be used to control what sort of synchronization the kernel will do
+when querying a file on a remote filesystem.
+This is done by ORing in one of the following values:
+.TP
+.B AT_STATX_SYNC_AS_STAT
+Do whatever
+.BR stat (2)
+does.
+This is the default and is very much filesystem-specific.
+.TP
+.B AT_STATX_FORCE_SYNC
+Force the attributes to be synchronized with the server.
+This may require that
+a network filesystem perform a data writeback to get the timestamps correct.
+.TP
+.B AT_STATX_DONT_SYNC
+Don't synchronize anything, but rather just take whatever
+the system has cached if possible.
+This may mean that the information returned is approximate, but,
+on a network filesystem, it may not involve a round trip to the server - even
+if no lease is held.
+.P
+The
+.I mask
+argument to
+.BR statx ()
+is used to tell the kernel which fields the caller is interested in.
+.I mask
+is an ORed combination of the following constants:
+.P
+.in +4n
+.TS
+lB l.
+STATX_TYPE	Want stx_mode & S_IFMT
+STATX_MODE	Want stx_mode & \[ti]S_IFMT
+STATX_NLINK	Want stx_nlink
+STATX_UID	Want stx_uid
+STATX_GID	Want stx_gid
+STATX_ATIME	Want stx_atime
+STATX_MTIME	Want stx_mtime
+STATX_CTIME	Want stx_ctime
+STATX_INO	Want stx_ino
+STATX_SIZE	Want stx_size
+STATX_BLOCKS	Want stx_blocks
+STATX_BASIC_STATS	[All of the above]
+STATX_BTIME	Want stx_btime
+STATX_ALL	The same as STATX_BASIC_STATS | STATX_BTIME.
+	It is deprecated and should not be used.
+STATX_MNT_ID	Want stx_mnt_id (since Linux 5.8)
+STATX_DIOALIGN	Want stx_dio_mem_align and stx_dio_offset_align
+	(since Linux 6.1; support varies by filesystem)
+.TE
+.in
+.P
+Note that, in general, the kernel does
+.I not
+reject values in
+.I mask
+other than the above.
+(For an exception, see
+.B EINVAL
+in errors.)
+Instead, it simply informs the caller which values are supported
+by this kernel and filesystem via the
+.I statx.stx_mask
+field.
+Therefore,
+.I "do not"
+simply set
+.I mask
+to
+.B UINT_MAX
+(all bits set),
+as one or more bits may, in the future, be used to specify an
+extension to the buffer.
+.SS
+The returned information
+The status information for the target file is returned in the
+.I statx
+structure pointed to by
+.IR statxbuf .
+Included in this is
+.I stx_mask
+which indicates what other information has been returned.
+.I stx_mask
+has the same format as the
+.I mask
+argument and bits are set in it to indicate
+which fields have been filled in.
+.P
+It should be noted that the kernel may return fields that weren't
+requested and may fail to return fields that were requested,
+depending on what the backing filesystem supports.
+(Fields that are given values despite being unrequested can just be ignored.)
+In either case,
+.I stx_mask
+will not be equal
+.IR mask .
+.P
+If a filesystem does not support a field or if it has
+an unrepresentable value (for instance, a file with an exotic type),
+then the mask bit corresponding to that field will be cleared in
+.I stx_mask
+even if the user asked for it and a dummy value will be filled in for
+compatibility purposes if one is available (e.g., a dummy UID and GID may be
+specified to mount under some circumstances).
+.P
+A filesystem may also fill in fields that the caller didn't ask for if it has
+values for them available and the information is available at no extra cost.
+If this happens, the corresponding bits will be set in
+.IR stx_mask .
+.P
+.\" Background: inode attributes are modified with i_mutex held, but
+.\" read by stat() without taking the mutex.
+.IR Note :
+for performance and simplicity reasons, different fields in the
+.I statx
+structure may contain state information from different moments
+during the execution of the system call.
+For example, if
+.I stx_mode
+or
+.I stx_uid
+is changed by another process by calling
+.BR chmod (2)
+or
+.BR chown (2),
+.BR stat ()
+might return the old
+.I stx_mode
+together with the new
+.IR stx_uid ,
+or the old
+.I stx_uid
+together with the new
+.IR stx_mode .
+.P
+Apart from
+.I stx_mask
+(which is described above), the fields in the
+.I statx
+structure are:
+.TP
+.I stx_blksize
+The "preferred" block size for efficient filesystem I/O.
+(Writing to a file in
+smaller chunks may cause an inefficient read-modify-rewrite.)
+.TP
+.I stx_attributes
+Further status information about the file (see below for more information).
+.TP
+.I stx_nlink
+The number of hard links on a file.
+.TP
+.I stx_uid
+This field contains the user ID of the owner of the file.
+.TP
+.I stx_gid
+This field contains the ID of the group owner of the file.
+.TP
+.I stx_mode
+The file type and mode.
+See
+.BR inode (7)
+for details.
+.TP
+.I stx_ino
+The inode number of the file.
+.TP
+.I stx_size
+The size of the file (if it is a regular file or a symbolic link) in bytes.
+The size of a symbolic link is the length of the pathname it contains,
+without a terminating null byte.
+.TP
+.I stx_blocks
+The number of blocks allocated to the file on the medium, in 512-byte units.
+(This may be smaller than
+.IR stx_size /512
+when the file has holes.)
+.TP
+.I stx_attributes_mask
+A mask indicating which bits in
+.I stx_attributes
+are supported by the VFS and the filesystem.
+.TP
+.I stx_atime
+The file's last access timestamp.
+.TP
+.I stx_btime
+The file's creation timestamp.
+.TP
+.I stx_ctime
+The file's last status change timestamp.
+.TP
+.I stx_mtime
+The file's last modification timestamp.
+.TP
+.IR stx_dev_major " and "  stx_dev_minor
+The device on which this file (inode) resides.
+.TP
+.IR stx_rdev_major " and "  stx_rdev_minor
+The device that this file (inode) represents if the file is of block or
+character device type.
+.TP
+.I stx_mnt_id
+.\" commit fa2fcf4f1df1559a0a4ee0f46915b496cc2ebf60
+The mount ID of the mount containing the file.
+This is the same number reported by
+.BR name_to_handle_at (2)
+and corresponds to the number in the first field in one of the records in
+.IR /proc/self/mountinfo .
+.TP
+.I stx_dio_mem_align
+The alignment (in bytes) required for user memory buffers for direct I/O
+.RB ( O_DIRECT )
+on this file,
+or 0 if direct I/O is not supported on this file.
+.IP
+.B STATX_DIOALIGN
+.RI ( stx_dio_mem_align
+and
+.IR stx_dio_offset_align )
+is supported on block devices since Linux 6.1.
+The support on regular files varies by filesystem;
+it is supported by ext4, f2fs, and xfs since Linux 6.1.
+.TP
+.I stx_dio_offset_align
+The alignment (in bytes) required for file offsets and I/O segment lengths
+for direct I/O
+.RB ( O_DIRECT )
+on this file,
+or 0 if direct I/O is not supported on this file.
+This will only be nonzero if
+.I stx_dio_mem_align
+is nonzero, and vice versa.
+.P
+For further information on the above fields, see
+.BR inode (7).
+.\"
+.SS File attributes
+The
+.I stx_attributes
+field contains a set of ORed flags that indicate additional attributes
+of the file.
+Note that any attribute that is not indicated as supported by
+.I stx_attributes_mask
+has no usable value here.
+The bits in
+.I stx_attributes_mask
+correspond bit-by-bit to
+.IR stx_attributes .
+.P
+The flags are as follows:
+.TP
+.B STATX_ATTR_COMPRESSED
+The file is compressed by the filesystem and may take extra resources
+to access.
+.TP
+.B STATX_ATTR_IMMUTABLE
+The file cannot be modified: it cannot be deleted or renamed,
+no hard links can be created to this file and no data can be written to it.
+See
+.BR chattr (1).
+.TP
+.B STATX_ATTR_APPEND
+The file can only be opened in append mode for writing.
+Random access writing
+is not permitted.
+See
+.BR chattr (1).
+.TP
+.B STATX_ATTR_NODUMP
+File is not a candidate for backup when a backup program such as
+.BR dump (8)
+is run.
+See
+.BR chattr (1).
+.TP
+.B STATX_ATTR_ENCRYPTED
+A key is required for the file to be encrypted by the filesystem.
+.TP
+.BR STATX_ATTR_VERITY " (since Linux 5.5)"
+.\" commit 3ad2522c64cff1f5aebb987b00683268f0cc7c29
+The file has fs-verity enabled.
+It cannot be written to, and all reads from it will be verified
+against a cryptographic hash that covers the
+entire file (e.g., via a Merkle tree).
+.TP
+.BR STATX_ATTR_DAX " (since Linux 5.8)"
+The file is in the DAX (cpu direct access) state.
+DAX state attempts to
+minimize software cache effects for both I/O and memory mappings of this file.
+It requires a file system which has been configured to support DAX.
+.IP
+DAX generally assumes all accesses are via CPU load / store instructions
+which can minimize overhead for small accesses,
+but may adversely affect CPU utilization for large transfers.
+.IP
+File I/O is done directly to/from user-space buffers and memory mapped I/O may
+be performed with direct memory mappings that bypass the kernel page cache.
+.IP
+While the DAX property tends to result in data being transferred synchronously,
+it does not give the same guarantees as the
+.B O_SYNC
+flag (see
+.BR open (2)),
+where data and the necessary metadata are transferred together.
+.IP
+A DAX file may support being mapped with the
+.B MAP_SYNC
+flag, which enables a
+program to use CPU cache flush instructions to persist CPU store operations
+without an explicit
+.BR fsync (2).
+See
+.BR mmap (2)
+for more information.
+.TP
+.BR STATX_ATTR_MOUNT_ROOT " (since Linux 5.8)"
+.\" commit 80340fe3605c0e78cfe496c3b3878be828cfdbfe
+The file is the root of a mount.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission is denied for one of the directories
+in the path prefix of
+.IR pathname .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I pathname
+or
+.I statxbuf
+is NULL or points to a location outside the process's
+accessible address space.
+.TP
+.B EINVAL
+Invalid flag specified in
+.IR flags .
+.TP
+.B EINVAL
+Reserved flag specified in
+.IR mask .
+(Currently, there is one such flag, designated by the constant
+.BR STATX__RESERVED ,
+with the value 0x80000000U.)
+.TP
+.B ELOOP
+Too many symbolic links encountered while traversing the pathname.
+.TP
+.B ENAMETOOLONG
+.I pathname
+is too long.
+.TP
+.B ENOENT
+A component of
+.I pathname
+does not exist, or
+.I pathname
+is an empty string and
+.B AT_EMPTY_PATH
+was not specified in
+.IR flags .
+.TP
+.B ENOMEM
+Out of memory (i.e., kernel memory).
+.TP
+.B ENOTDIR
+A component of the path prefix of
+.I pathname
+is not a directory or
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 4.11,
+glibc 2.28.
+.SH SEE ALSO
+.BR ls (1),
+.BR stat (1),
+.BR access (2),
+.BR chmod (2),
+.BR chown (2),
+.BR name_to_handle_at (2),
+.BR readlink (2),
+.BR stat (2),
+.BR utime (2),
+.BR proc (5),
+.BR capabilities (7),
+.BR inode (7),
+.BR symlink (7)
diff --git a/man/man2/stime.2 b/man/man2/stime.2
new file mode 100644
index 000000000..70ad2be83
--- /dev/null
+++ b/man/man2/stime.2
@@ -0,0 +1,73 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 2001-03-16 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH stime 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stime \- set time
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "[[deprecated]] int stime(const time_t *" t );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR stime ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+.BR NOTE :
+This function is deprecated;
+use
+.BR clock_settime (2)
+instead.
+.P
+.BR stime ()
+sets the system's idea of the time and date.
+The time, pointed
+to by \fIt\fP, is measured in seconds since the
+Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.BR stime ()
+may be executed only by the superuser.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Error in getting information from user space.
+.TP
+.B EPERM
+The calling process has insufficient privilege.
+Under Linux, the
+.B CAP_SYS_TIME
+privilege is required.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4.
+.P
+Starting with glibc 2.31,
+this function is no longer available to newly linked applications
+and is no longer declared in
+.IR <time.h> .
+.SH SEE ALSO
+.BR date (1),
+.BR settimeofday (2),
+.BR capabilities (7)
diff --git a/man/man2/stty.2 b/man/man2/stty.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/stty.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/subpage_prot.2 b/man/man2/subpage_prot.2
new file mode 100644
index 000000000..c006821c1
--- /dev/null
+++ b/man/man2/subpage_prot.2
@@ -0,0 +1,118 @@
+.\" Copyright (c) 2010 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" based on a proposal from Stephan Mueller <smueller@atsec.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Various pieces of text taken from the kernel source and the commentary
+.\" in Linux commit fa28237cfcc5827553044cbd6ee52e33692b0faa
+.\" both written by Paul Mackerras <paulus@samba.org>
+.\"
+.TH subpage_prot 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+subpage_prot \- define a subpage protection for an address range
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_subpage_prot, unsigned long " addr ", unsigned long " len ,
+.BI "            uint32_t *" map );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR subpage_prot (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+The PowerPC-specific
+.BR subpage_prot ()
+system call provides the facility to control the access
+permissions on individual 4\ kB subpages on systems configured with
+a page size of 64\ kB.
+.P
+The protection map is applied to the memory pages in the region starting at
+.I addr
+and continuing for
+.I len
+bytes.
+Both of these arguments must be aligned to a 64-kB boundary.
+.P
+The protection map is specified in the buffer pointed to by
+.IR map .
+The map has 2 bits per 4\ kB subpage;
+thus each 32-bit word specifies the protections of 16 4\ kB subpages
+inside a 64\ kB page
+(so, the number of 32-bit words pointed to by
+.I map
+should equate to the number of 64-kB pages specified by
+.IR len ).
+Each 2-bit field in the protection map is either 0 to allow any access,
+1 to prevent writes, or 2 or 3 to prevent all accesses.
+.SH RETURN VALUE
+On success,
+.BR subpage_prot ()
+returns 0.
+Otherwise, one of the error codes specified below is returned.
+.SH ERRORS
+.TP
+.B EFAULT
+The buffer referred to by
+.I map
+is not accessible.
+.TP
+.B EINVAL
+The
+.I addr
+or
+.I len
+arguments are incorrect.
+Both of these arguments must be aligned to a multiple of the system page size,
+and they must not refer to a region outside of the
+address space of the process or to a region that consists of huge pages.
+.TP
+.B ENOMEM
+Out of memory.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.25 (PowerPC).
+.P
+The system call is provided only if the kernel is configured with
+.BR CONFIG_PPC_64K_PAGES .
+.SH NOTES
+Normal page protections (at the 64-kB page level) also apply;
+the subpage protection mechanism is an additional constraint,
+so putting 0 in a 2-bit field won't allow writes to a page that is otherwise
+write-protected.
+.SS Rationale
+This system call is provided to assist writing emulators that
+operate using 64-kB pages on PowerPC systems.
+When emulating systems such as x86, which uses a smaller page size,
+the emulator can no longer use the memory-management unit (MMU)
+and normal system calls for controlling page protections.
+(The emulator could emulate the MMU by checking and possibly remapping
+the address for each memory access in software, but that is slow.)
+The idea is that the emulator supplies an array of protection masks
+to apply to a specified range of virtual addresses.
+These masks are applied at the level where hardware page-table entries (PTEs)
+are inserted into the hardware page table based on the Linux PTEs,
+so the Linux PTEs are not affected.
+Implicit in this is that the regions of the address space that are
+protected are switched to use 4-kB hardware pages rather than 64-kB
+hardware pages (on machines with hardware 64-kB page support).
+.\" In the initial implementation, it was the case that:
+.\"     In fact the whole process is switched to use 4 kB hardware pages when the
+.\"     subpage_prot system call is used, but this could be improved in future
+.\"     to switch only the affected segments.
+.\" But Paul Mackerass says (Oct 2010): I'm pretty sure we now only switch
+.\" the affected segment, not the whole process.
+.SH SEE ALSO
+.BR mprotect (2),
+.BR syscall (2)
+.P
+.I Documentation/admin\-guide/mm/hugetlbpage.rst
+in the Linux kernel source tree
diff --git a/man/man2/swapoff.2 b/man/man2/swapoff.2
new file mode 100644
index 000000000..2bd424c14
--- /dev/null
+++ b/man/man2/swapoff.2
@@ -0,0 +1 @@
+.so man2/swapon.2
diff --git a/man/man2/swapon.2 b/man/man2/swapon.2
new file mode 100644
index 000000000..b2651fc39
--- /dev/null
+++ b/man/man2/swapon.2
@@ -0,0 +1,202 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-07-22 by Michael Chastain <mec@duracef.shout.net>
+.\" Modified 1995-07-23 by aeb
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998-09-08 by aeb
+.\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2004-10-10 by aeb
+.\" 2004-12-14 mtk, Anand Kumria: added new errors
+.\" 2007-06-22 Ivana Varekova <varekova@redhat.com>, mtk
+.\"     Update text describing limit on number of swap files.
+.\" 2021-01-17 Alex Baranowski <alex@euro-linux.com>
+.\"     Update information about available swap files decreased by
+.\"     CONFIG_DEVICE_PRIVATE option.
+.\"
+.\" FIXME Linux 3.11 added SWAP_FLAG_DISCARD_ONCE and SWAP_FLAG_DISCARD_PAGES
+.\"	commit dcf6b7ddd7df8965727746f89c59229b23180e5a
+.\"	Author: Rafael Aquini <aquini@redhat.com>
+.\"	Date:   Wed Jul 3 15:02:46 2013 -0700
+.\"
+.TH swapon 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+swapon, swapoff \- start/stop swapping to file/device
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/swap.h>
+.P
+.BI "int swapon(const char *" path ", int " swapflags );
+.BI "int swapoff(const char *" path );
+.fi
+.SH DESCRIPTION
+.BR swapon ()
+sets the swap area to the file or block device specified by
+.IR path .
+.BR swapoff ()
+stops swapping to the file or block device specified by
+.IR path .
+.P
+If the
+.B SWAP_FLAG_PREFER
+flag is specified in the
+.BR swapon ()
+.I swapflags
+argument, the new swap area will have a higher priority than default.
+The priority is encoded within
+.I swapflags
+as:
+.P
+.in +4n
+.EX
+.I "(prio << SWAP_FLAG_PRIO_SHIFT) & SWAP_FLAG_PRIO_MASK"
+.EE
+.in
+.P
+If the
+.B SWAP_FLAG_DISCARD
+flag is specified in the
+.BR swapon ()
+.I swapflags
+argument, freed swap pages will be discarded before they are reused,
+if the swap device supports the discard or trim operation.
+(This may improve performance on some Solid State Devices,
+but often it does not.)
+See also NOTES.
+.P
+These functions may be used only by a privileged process (one having the
+.B CAP_SYS_ADMIN
+capability).
+.SS Priority
+Each swap area has a priority, either high or low.
+The default priority is low.
+Within the low-priority areas,
+newer areas are even lower priority than older areas.
+.P
+All priorities set with
+.I swapflags
+are high-priority, higher than default.
+They may have any nonnegative value chosen by the caller.
+Higher numbers mean higher priority.
+.P
+Swap pages are allocated from areas in priority order,
+highest priority first.
+For areas with different priorities,
+a higher-priority area is exhausted before using a lower-priority area.
+If two or more areas have the same priority,
+and it is the highest priority available,
+pages are allocated on a round-robin basis between them.
+.P
+As of Linux 1.3.6, the kernel usually follows these rules,
+but there are exceptions.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBUSY
+(for
+.BR swapon ())
+The specified
+.I path
+is already being used as a swap area.
+.TP
+.B EINVAL
+The file
+.I path
+exists, but refers neither to a regular file nor to a block device;
+.TP
+.B EINVAL
+.RB ( swapon ())
+The indicated path does not contain a valid swap signature or
+resides on an in-memory filesystem such as
+.BR tmpfs (5).
+.TP
+.BR EINVAL " (since Linux 3.4)"
+.RB ( swapon ())
+An invalid flag value was specified in
+.IR swapflags .
+.TP
+.B EINVAL
+.RB ( swapoff ())
+.I path
+is not currently a swap area.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+The file
+.I path
+does not exist.
+.TP
+.B ENOMEM
+The system has insufficient memory to start swapping.
+.TP
+.B EPERM
+The caller does not have the
+.B CAP_SYS_ADMIN
+capability.
+Alternatively, the maximum number of swap files are already in use;
+see NOTES below.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+The
+.I swapflags
+argument was introduced in Linux 1.3.2.
+.SH NOTES
+The partition or path must be prepared with
+.BR mkswap (8).
+.P
+There is an upper limit on the number of swap files that may be used,
+defined by the kernel constant
+.BR MAX_SWAPFILES .
+Before Linux 2.4.10,
+.B MAX_SWAPFILES
+has the value 8;
+since Linux 2.4.10, it has the value 32.
+Since Linux 2.6.18, the limit is decreased by 2 (thus 30),
+since Linux 5.19, the limit is decreased by 3 (thus: 29)
+if the kernel is built with the
+.B CONFIG_MIGRATION
+option
+(which reserves two swap table entries for the page migration features of
+.BR mbind (2)
+and
+.BR migrate_pages (2)).
+Since Linux 2.6.32, the limit is further decreased by 1
+if the kernel is built with the
+.B CONFIG_MEMORY_FAILURE
+option.
+Since Linux 5.14, the limit is further decreased by 4
+if the kernel is built with the
+.B CONFIG_DEVICE_PRIVATE
+option.
+Since Linux 5.19, the limit is further decreased by 1
+if the kernel is built with the
+.B CONFIG_PTE_MARKER
+option.
+.P
+Discard of swap pages was introduced in Linux 2.6.29,
+then made conditional
+on the
+.B SWAP_FLAG_DISCARD
+flag in Linux 2.6.36,
+.\" To be precise: 2.6.35.5
+which still discards the
+entire swap area when
+.BR swapon ()
+is called, even if that flag bit is not set.
+.SH SEE ALSO
+.BR mkswap (8),
+.BR swapoff (8),
+.BR swapon (8)
diff --git a/man/man2/symlink.2 b/man/man2/symlink.2
new file mode 100644
index 000000000..21ab4fa45
--- /dev/null
+++ b/man/man2/symlink.2
@@ -0,0 +1,265 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\"		and Copyright (C) 2006, 2014 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-24 by Rik Faith
+.\" Modified 1996-04-26 by Nick Duffek <nsd@bbc.com>
+.\" Modified 1996-11-06 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH symlink 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+symlink, symlinkat \- make a new name for a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int symlink(const char *" target ", const char *" linkpath );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of " AT_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int symlinkat(const char *" target ", int " newdirfd \
+", const char *" linkpath );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR symlink ():
+.nf
+    _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.P
+.BR symlinkat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+.BR symlink ()
+creates a symbolic link named
+.I linkpath
+which contains the string
+.IR target .
+.P
+Symbolic links are interpreted at run time as if the contents of the
+link had been substituted into the path being followed to find a file or
+directory.
+.P
+Symbolic links may contain
+.I ..
+path components, which (if used at the start of the link) refer to the
+parent directories of that in which the link resides.
+.P
+A symbolic link (also known as a soft link) may point to an existing
+file or to a nonexistent one; the latter case is known as a dangling
+link.
+.P
+The permissions of a symbolic link are irrelevant; the ownership is
+ignored when following the link
+(except when the
+.I protected_symlinks
+feature is enabled, as explained in
+.BR proc (5)),
+but is checked when removal or
+renaming of the link is requested and the link is in a directory with
+the sticky bit
+.RB ( S_ISVTX )
+set.
+.P
+If
+.I linkpath
+exists, it will
+.I not
+be overwritten.
+.SS symlinkat()
+The
+.BR symlinkat ()
+system call operates in exactly the same way as
+.BR symlink (),
+except for the differences described here.
+.P
+If the pathname given in
+.I linkpath
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I newdirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR symlink ()
+for a relative pathname).
+.P
+If
+.I linkpath
+is relative and
+.I newdirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I linkpath
+is interpreted relative to the current working
+directory of the calling process (like
+.BR symlink ()).
+.P
+If
+.I linkpath
+is absolute, then
+.I newdirfd
+is ignored.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR symlinkat ().
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Write access to the directory containing
+.I linkpath
+is denied, or one of the directories in the path prefix of
+.I linkpath
+did not allow search permission.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( symlinkat ())
+.I linkpath
+is relative but
+.I newdirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EDQUOT
+The user's quota of resources on the filesystem has been exhausted.
+The resources could be inodes or disk blocks, depending on the filesystem
+implementation.
+.TP
+.B EEXIST
+.I linkpath
+already exists.
+.TP
+.B EFAULT
+.IR target " or " linkpath " points outside your accessible address space."
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in resolving
+.IR linkpath .
+.TP
+.B ENAMETOOLONG
+.IR target " or " linkpath " was too long."
+.TP
+.B ENOENT
+A directory component in
+.I linkpath
+does not exist or is a dangling symbolic link, or
+.I target
+or
+.I linkpath
+is an empty string.
+.TP
+.B ENOENT
+.RB ( symlinkat ())
+.I linkpath
+is a relative pathname and
+.I newdirfd
+refers to a directory that has been deleted.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSPC
+The device containing the file has no room for the new directory
+entry.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.I linkpath
+is not, in fact, a directory.
+.TP
+.B ENOTDIR
+.RB ( symlinkat ())
+.I linkpath
+is relative and
+.I newdirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EPERM
+The filesystem containing
+.I linkpath
+does not support the creation of symbolic links.
+.TP
+.B EROFS
+.I linkpath
+is on a read-only filesystem.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR symlink ()
+SVr4, 4.3BSD, POSIX.1-2001.
+.\" SVr4 documents additional error codes EDQUOT and ENOSYS.
+.\" See
+.\" .BR open (2)
+.\" re multiple files with the same name, and NFS.
+.TP
+.BR symlinkat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.SS glibc notes
+On older kernels where
+.BR symlinkat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR symlink ().
+When
+.I linkpath
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.I /proc/self/fd
+that corresponds to the
+.I newdirfd
+argument.
+.SH NOTES
+No checking of
+.I target
+is done.
+.P
+Deleting the name referred to by a symbolic link will actually delete the
+file (unless it also has other hard links).
+If this behavior is not desired, use
+.BR link (2).
+.SH SEE ALSO
+.BR ln (1),
+.BR namei (1),
+.BR lchown (2),
+.BR link (2),
+.BR lstat (2),
+.BR open (2),
+.BR readlink (2),
+.BR rename (2),
+.BR unlink (2),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/symlinkat.2 b/man/man2/symlinkat.2
new file mode 100644
index 000000000..78568cd0a
--- /dev/null
+++ b/man/man2/symlinkat.2
@@ -0,0 +1 @@
+.so man2/symlink.2
diff --git a/man/man2/sync.2 b/man/man2/sync.2
new file mode 100644
index 000000000..1c0c7d7b4
--- /dev/null
+++ b/man/man2/sync.2
@@ -0,0 +1,148 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\" and Copyright (c) 2011 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified Sat Jul 24 12:02:47 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 15 Apr 1995 by Michael Chastain <mec@shell.portal.com>:
+.\"   Added reference to `bdflush(2)'.
+.\" Modified 960414 by Andries Brouwer <aeb@cwi.nl>:
+.\"   Added the fact that since 1.3.20 sync actually waits.
+.\" Modified Tue Oct 22 22:27:07 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-10-10 by aeb, following Michael Kerrisk.
+.\" 2011-09-07, mtk, Added syncfs() documentation,
+.\"
+.TH sync 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sync, syncfs \- commit filesystem caches to disk
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B void sync(void);
+.P
+.BI "int syncfs(int " fd );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sync ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.P
+.BR syncfs ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.BR sync ()
+causes all pending modifications to filesystem metadata and cached file
+data to be written to the underlying filesystems.
+.P
+.BR syncfs ()
+is like
+.BR sync (),
+but synchronizes just the filesystem containing file
+referred to by the open file descriptor
+.IR fd .
+.SH RETURN VALUE
+.BR syncfs ()
+returns 0 on success;
+on error, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.BR sync ()
+is always successful.
+.P
+.BR syncfs ()
+can fail for at least the following reasons:
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EIO
+An error occurred during synchronization.
+This error may relate to data written to any file on the filesystem, or on
+metadata related to the filesystem itself.
+.TP
+.B ENOSPC
+Disk space was exhausted while synchronizing.
+.TP
+.B ENOSPC
+.TQ
+.B EDQUOT
+Data was written to a file on NFS or another filesystem which does not
+allocate space at the time of a
+.BR write (2)
+system call, and some previous write failed due to insufficient
+storage space.
+.SH VERSIONS
+According to the standard specification (e.g., POSIX.1-2001),
+.BR sync ()
+schedules the writes, but may return before the actual
+writing is done.
+However Linux waits for I/O completions,
+and thus
+.BR sync ()
+or
+.BR syncfs ()
+provide the same guarantees as
+.BR fsync ()
+called on every file in
+the system or filesystem respectively.
+.SH STANDARDS
+.TP
+.BR sync ()
+POSIX.1-2008.
+.TP
+.BR syncfs ()
+Linux.
+.SH HISTORY
+.TP
+.BR sync ()
+POSIX.1-2001, SVr4, 4.3BSD.
+.TP
+.BR syncfs ()
+Linux 2.6.39,
+glibc 2.14.
+.P
+Since glibc 2.2.2, the Linux prototype for
+.BR sync ()
+is as listed above,
+following the various standards.
+In glibc 2.2.1 and earlier,
+it was "int sync(void)", and
+.BR sync ()
+always returned 0.
+.P
+In mainline kernel versions prior to Linux 5.8,
+.BR syncfs ()
+will fail only when passed a bad file descriptor
+.RB ( EBADF ).
+Since Linux 5.8,
+.\" commit 735e4ae5ba28c886d249ad04d3c8cc097dad6336
+.BR syncfs ()
+will also report an error if one or more inodes failed
+to be written back since the last
+.BR syncfs ()
+call.
+.SH BUGS
+Before Linux 1.3.20, Linux did not wait for I/O to complete
+before returning.
+.SH SEE ALSO
+.BR sync (1),
+.BR fdatasync (2),
+.BR fsync (2)
diff --git a/man/man2/sync_file_range.2 b/man/man2/sync_file_range.2
new file mode 100644
index 000000000..2f6fadbe9
--- /dev/null
+++ b/man/man2/sync_file_range.2
@@ -0,0 +1,213 @@
+.\" Copyright (c) 2006 Andrew Morton <akpm@osdl.org>
+.\" and Copyright 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2006-07-05 Initial creation, Michael Kerrisk based on
+.\"     Andrew Morton's comments in fs/sync.c
+.\" 2010-10-09, mtk, Document sync_file_range2()
+.\"
+.TH sync_file_range 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sync_file_range \- sync a file segment with disk
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #define _FILE_OFFSET_BITS 64
+.B #include <fcntl.h>
+.P
+.BI "int sync_file_range(int " fd ", off_t " offset ", off_t " nbytes ,
+.BI "                    unsigned int " flags );
+.fi
+.SH DESCRIPTION
+.BR sync_file_range ()
+permits fine control when synchronizing the open file referred to by the
+file descriptor
+.I fd
+with disk.
+.P
+.I offset
+is the starting byte of the file range to be synchronized.
+.I nbytes
+specifies the length of the range to be synchronized, in bytes; if
+.I nbytes
+is zero, then all bytes from
+.I offset
+through to the end of file are synchronized.
+Synchronization is in units of the system page size:
+.I offset
+is rounded down to a page boundary;
+.I (offset+nbytes\-1)
+is rounded up to a page boundary.
+.P
+The
+.I flags
+bit-mask argument can include any of the following values:
+.TP
+.B SYNC_FILE_RANGE_WAIT_BEFORE
+Wait upon write-out of all pages in the specified range
+that have already been submitted to the device driver for write-out
+before performing any write.
+.TP
+.B SYNC_FILE_RANGE_WRITE
+Initiate write-out of all dirty pages in the specified
+range which are not presently submitted write-out.
+Note that even this may block if you attempt to
+write more than request queue size.
+.TP
+.B SYNC_FILE_RANGE_WAIT_AFTER
+Wait upon write-out of all pages in the range
+after performing any write.
+.P
+Specifying
+.I flags
+as 0 is permitted, as a no-op.
+.SS Warning
+This system call is extremely dangerous and should not be used in portable
+programs.
+None of these operations writes out the file's metadata.
+Therefore, unless the application is strictly performing overwrites of
+already-instantiated disk blocks, there are no guarantees that the data will
+be available after a crash.
+There is no user interface to know if a write is purely an overwrite.
+On filesystems using copy-on-write semantics (e.g.,
+.IR btrfs )
+an overwrite of existing allocated blocks is impossible.
+When writing into preallocated space,
+many filesystems also require calls into the block
+allocator, which this system call does not sync out to disk.
+This system call does not flush disk write caches and thus does not provide
+any data integrity on systems with volatile disk write caches.
+.SS Some details
+.B SYNC_FILE_RANGE_WAIT_BEFORE
+and
+.B SYNC_FILE_RANGE_WAIT_AFTER
+will detect any
+I/O errors or
+.B ENOSPC
+conditions and will return these to the caller.
+.P
+Useful combinations of the
+.I flags
+bits are:
+.TP
+.B SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE
+Ensures that all pages
+in the specified range which were dirty when
+.BR sync_file_range ()
+was called are placed
+under write-out.
+This is a start-write-for-data-integrity operation.
+.TP
+.B SYNC_FILE_RANGE_WRITE
+Start write-out of all dirty pages in the specified range which
+are not presently under write-out.
+This is an asynchronous flush-to-disk
+operation.
+This is not suitable for data integrity operations.
+.TP
+.BR SYNC_FILE_RANGE_WAIT_BEFORE " (or " SYNC_FILE_RANGE_WAIT_AFTER )
+Wait for
+completion of write-out of all pages in the specified range.
+This can be used after an earlier
+.B SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE
+operation to wait for completion of that operation, and obtain its result.
+.TP
+.B SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE | \
+SYNC_FILE_RANGE_WAIT_AFTER
+This is a write-for-data-integrity operation
+that will ensure that all pages in the specified range which were dirty when
+.BR sync_file_range ()
+was called are committed to disk.
+.SH RETURN VALUE
+On success,
+.BR sync_file_range ()
+returns 0; on failure \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+.I flags
+specifies an invalid bit; or
+.I offset
+or
+.I nbytes
+is invalid.
+.TP
+.B EIO
+I/O error.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ENOSPC
+Out of disk space.
+.TP
+.B ESPIPE
+.I fd
+refers to something other than a regular file, a block device, or
+a directory.
+.SH VERSIONS
+.SS sync_file_range2()
+Some architectures (e.g., PowerPC, ARM)
+need 64-bit arguments to be aligned in a suitable pair of registers.
+.\" See kernel commit edd5cd4a9424f22b0fa08bef5e299d41befd5622
+On such architectures, the call signature of
+.BR sync_file_range ()
+shown in the SYNOPSIS would force
+a register to be wasted as padding between the
+.I fd
+and
+.I offset
+arguments.
+(See
+.BR syscall (2)
+for details.)
+Therefore, these architectures define a different
+system call that orders the arguments suitably:
+.P
+.in +4n
+.EX
+.BI "int sync_file_range2(int " fd ", unsigned int " flags ,
+.BI "                     off_t " offset ", off_t " nbytes );
+.EE
+.in
+.P
+The behavior of this system call is otherwise exactly the same as
+.BR sync_file_range ().
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.17.
+.SS sync_file_range2()
+A system call with this signature first appeared on the ARM architecture
+in Linux 2.6.20, with the name
+.BR arm_sync_file_range ().
+It was renamed in Linux 2.6.22,
+when the analogous system call was added for PowerPC.
+On architectures where glibc support is provided,
+glibc transparently wraps
+.BR sync_file_range2 ()
+under the name
+.BR sync_file_range ().
+.SH NOTES
+.B _FILE_OFFSET_BITS
+should be defined to be 64 in code that takes the address of
+.BR sync_file_range ,
+if the code is intended to be portable
+to traditional 32-bit x86 and ARM platforms where
+.BR off_t 's
+width defaults to 32 bits.
+.SH SEE ALSO
+.BR fdatasync (2),
+.BR fsync (2),
+.BR msync (2),
+.BR sync (2)
diff --git a/man/man2/sync_file_range2.2 b/man/man2/sync_file_range2.2
new file mode 100644
index 000000000..ad7a1e6c7
--- /dev/null
+++ b/man/man2/sync_file_range2.2
@@ -0,0 +1 @@
+.so man2/sync_file_range.2
diff --git a/man/man2/syncfs.2 b/man/man2/syncfs.2
new file mode 100644
index 000000000..555579827
--- /dev/null
+++ b/man/man2/syncfs.2
@@ -0,0 +1 @@
+.so man2/sync.2
diff --git a/man/man2/syscall.2 b/man/man2/syscall.2
new file mode 100644
index 000000000..82f02ebe1
--- /dev/null
+++ b/man/man2/syscall.2
@@ -0,0 +1,367 @@
+'\" t
+.\" Copyright (c) 1980, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)syscall.2	8.1 (Berkeley) 6/16/93
+.\"
+.\"
+.\" 2002-03-20  Christoph Hellwig <hch@infradead.org>
+.\"	- adopted for Linux
+.\" 2015-01-17, Kees Cook <keescook@chromium.org>
+.\"	Added mips and arm64.
+.\"
+.TH syscall 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+syscall \- indirect system call
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "long syscall(long " number ", ...);"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR syscall ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    Before glibc 2.19:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+.BR syscall ()
+is a small library function that invokes
+the system call whose assembly language
+interface has the specified
+.I number
+with the specified arguments.
+Employing
+.BR syscall ()
+is useful, for example,
+when invoking a system call that has no wrapper function in the C library.
+.P
+.BR syscall ()
+saves CPU registers before making the system call,
+restores the registers upon return from the system call,
+and stores any error returned by the system call in
+.BR errno (3).
+.P
+Symbolic constants for system call numbers can be found in the header file
+.IR <sys/syscall.h> .
+.SH RETURN VALUE
+The return value is defined by the system call being invoked.
+In general, a 0 return value indicates success.
+A \-1 return value indicates an error,
+and an error number is stored in
+.IR errno .
+.SH ERRORS
+.TP
+.B ENOSYS
+The requested system call number is not implemented.
+.P
+Other errors are specific to the invoked system call.
+.SH NOTES
+.BR syscall ()
+first appeared in
+4BSD.
+.SS Architecture-specific requirements
+Each architecture ABI has its own requirements on how
+system call arguments are passed to the kernel.
+For system calls that have a glibc wrapper (e.g., most system calls),
+glibc handles the details of copying arguments to the right registers
+in a manner suitable for the architecture.
+However, when using
+.BR syscall ()
+to make a system call,
+the caller might need to handle architecture-dependent details;
+this requirement is most commonly encountered on certain 32-bit architectures.
+.P
+For example, on the ARM architecture Embedded ABI (EABI), a
+64-bit value (e.g.,
+.IR "long long" )
+must be aligned to an even register pair.
+Thus, using
+.BR syscall ()
+instead of the wrapper provided by glibc,
+the
+.BR readahead (2)
+system call would be invoked as follows on the ARM architecture with the EABI
+in little endian mode:
+.P
+.in +4n
+.EX
+syscall(SYS_readahead, fd, 0,
+        (unsigned int) (offset & 0xFFFFFFFF),
+        (unsigned int) (offset >> 32),
+        count);
+.EE
+.in
+.P
+Since the offset argument is 64 bits, and the first argument
+.RI ( fd )
+is passed in
+.IR r0 ,
+the caller must manually split and align the 64-bit value
+so that it is passed in the
+.IR r2 / r3
+register pair.
+That means inserting a dummy value into
+.I r1
+(the second argument of 0).
+Care also must be taken so that the split follows endian conventions
+(according to the C ABI for the platform).
+.P
+Similar issues can occur on MIPS with the O32 ABI,
+on PowerPC and parisc with the 32-bit ABI, and on Xtensa.
+.\" Mike Frysinger: this issue ends up forcing MIPS
+.\" O32 to take 7 arguments to syscall()
+.P
+.\" See arch/parisc/kernel/sys_parisc.c.
+Note that while the parisc C ABI also uses aligned register pairs,
+it uses a shim layer to hide the issue from user space.
+.P
+The affected system calls are
+.BR fadvise64_64 (2),
+.BR ftruncate64 (2),
+.BR posix_fadvise (2),
+.BR pread64 (2),
+.BR pwrite64 (2),
+.BR readahead (2),
+.BR sync_file_range (2),
+and
+.BR truncate64 (2).
+.P
+.\" You need to look up the syscalls directly in the kernel source to see if
+.\" they should be in this list.  For example, look at fs/read_write.c and
+.\" the function signatures that do:
+.\" ..., unsigned long, pos_l, unsigned long, pos_h, ...
+.\" If they use off_t, then they most likely do not belong in this list.
+This does not affect syscalls that manually split and assemble 64-bit values
+such as
+.BR _llseek (2),
+.BR preadv (2),
+.BR preadv2 (2),
+.BR pwritev (2),
+and
+.BR pwritev2 (2).
+Welcome to the wonderful world of historical baggage.
+.SS Architecture calling conventions
+Every architecture has its own way of invoking and passing arguments to the
+kernel.
+The details for various architectures are listed in the two tables below.
+.P
+The first table lists the instruction used to transition to kernel mode
+(which might not be the fastest or best way to transition to the kernel,
+so you might have to refer to
+.BR vdso (7)),
+the register used to indicate the system call number,
+the register(s) used to return the system call result,
+and the register used to signal an error.
+.if t \{\
+.ft CW
+\}
+.TS
+l2	l2	l2	l2	l1	l2	l.
+Arch/ABI	Instruction	System	Ret	Ret	Error	Notes
+		call #	val	val2
+_
+alpha	callsys	v0	v0	a4	a3	1, 6
+arc	trap0	r8	r0	-	-
+arm/OABI	swi NR	-	r0	-	-	2
+arm/EABI	swi 0x0	r7	r0	r1	-
+arm64	svc #0	w8	x0	x1	-
+blackfin	excpt 0x0	P0	R0	-	-
+i386	int $0x80	eax	eax	edx	-
+ia64	break 0x100000	r15	r8	r9	r10	1, 6
+loongarch	syscall 0	a7	a0	-	-
+m68k	trap #0	d0	d0	-	-
+microblaze	brki r14,8	r12	r3	-	-
+mips	syscall	v0	v0	v1	a3	1, 6
+nios2	trap	r2	r2	-	r7
+parisc	ble 0x100(%sr2, %r0)	r20	r28	-	-
+powerpc	sc	r0	r3	-	r0	1
+powerpc64	sc	r0	r3	-	cr0.SO	1
+riscv	ecall	a7	a0	a1	-
+s390	svc 0	r1	r2	r3	-	3
+s390x	svc 0	r1	r2	r3	-	3
+superh	trapa #31	r3	r0	r1	-	4, 6
+sparc/32	t 0x10	g1	o0	o1	psr/csr	1, 6
+sparc/64	t 0x6d	g1	o0	o1	psr/csr	1, 6
+tile	swint1	R10	R00	-	R01	1
+x86-64	syscall	rax	rax	rdx	-	5
+x32	syscall	rax	rax	rdx	-	5
+xtensa	syscall	a2	a2	-	-
+.TE
+.P
+Notes:
+.IP \[bu] 3
+On a few architectures,
+a register is used as a boolean
+(0 indicating no error, and \-1 indicating an error) to signal that the
+system call failed.
+The actual error value is still contained in the return register.
+On sparc, the carry bit
+.RI ( csr )
+in the processor status register
+.RI ( psr )
+is used instead of a full register.
+On powerpc64, the summary overflow bit
+.RI ( SO )
+in field 0 of the condition register
+.RI ( cr0 )
+is used.
+.IP \[bu]
+.I NR
+is the system call number.
+.IP \[bu]
+For s390 and s390x,
+.I NR
+(the system call number) may be passed directly with
+.I "svc\ NR"
+if it is less than 256.
+.IP \[bu]
+On SuperH additional trap numbers are supported for historic reasons, but
+.BR trapa #31
+is the recommended "unified" ABI.
+.IP \[bu]
+The x32 ABI shares syscall table with x86-64 ABI, but there are some
+nuances:
+.RS
+.IP \[bu] 3
+In order to indicate that a system call is called under the x32 ABI,
+an additional bit,
+.BR __X32_SYSCALL_BIT ,
+is bitwise ORed with the system call number.
+The ABI used by a process affects some process behaviors,
+including signal handling or system call restarting.
+.IP \[bu]
+Since x32 has different sizes for
+.I long
+and pointer types, layouts of some (but not all;
+.I struct timeval
+or
+.I struct rlimit
+are 64-bit, for example) structures are different.
+In order to handle this,
+additional system calls are added to the system call table,
+starting from number 512
+(without the
+.BR __X32_SYSCALL_BIT ).
+For example,
+.B __NR_readv
+is defined as 19 for the x86-64 ABI and as
+.IR __X32_SYSCALL_BIT " | " \fB515\fP
+for the x32 ABI.
+Most of these additional system calls are actually identical
+to the system calls used for providing i386 compat.
+There are some notable exceptions, however, such as
+.BR preadv2 (2),
+which uses
+.I struct iovec
+entities with 4-byte pointers and sizes ("compat_iovec" in kernel terms),
+but passes an 8-byte
+.I pos
+argument in a single register and not two, as is done in every other ABI.
+.RE
+.IP \[bu]
+Some architectures
+(namely, Alpha, IA-64, MIPS, SuperH, sparc/32, and sparc/64)
+use an additional register ("Retval2" in the above table)
+to pass back a second return value from the
+.BR pipe (2)
+system call;
+Alpha uses this technique in the architecture-specific
+.BR getxpid (2),
+.BR getxuid (2),
+and
+.BR getxgid (2)
+system calls as well.
+Other architectures do not use the second return value register
+in the system call interface, even if it is defined in the System V ABI.
+.if t \{\
+.in
+.ft P
+\}
+.P
+The second table shows the registers used to pass the system call arguments.
+.if t \{\
+.ft CW
+\}
+.TS
+l	l2	l2	l2	l2	l2	l2	l2	l.
+Arch/ABI	arg1	arg2	arg3	arg4	arg5	arg6	arg7	Notes
+_
+alpha	a0	a1	a2	a3	a4	a5	-
+arc	r0	r1	r2	r3	r4	r5	-
+arm/OABI	r0	r1	r2	r3	r4	r5	r6
+arm/EABI	r0	r1	r2	r3	r4	r5	r6
+arm64	x0	x1	x2	x3	x4	x5	-
+blackfin	R0	R1	R2	R3	R4	R5	-
+i386	ebx	ecx	edx	esi	edi	ebp	-
+ia64	out0	out1	out2	out3	out4	out5	-
+loongarch	a0	a1	a2	a3	a4	a5	a6
+m68k	d1	d2	d3	d4	d5	a0	-
+microblaze	r5	r6	r7	r8	r9	r10	-
+mips/o32	a0	a1	a2	a3	-	-	-	1
+mips/n32,64	a0	a1	a2	a3	a4	a5	-
+nios2	r4	r5	r6	r7	r8	r9	-
+parisc	r26	r25	r24	r23	r22	r21	-
+powerpc	r3	r4	r5	r6	r7	r8	r9
+powerpc64	r3	r4	r5	r6	r7	r8	-
+riscv	a0	a1	a2	a3	a4	a5	-
+s390	r2	r3	r4	r5	r6	r7	-
+s390x	r2	r3	r4	r5	r6	r7	-
+superh	r4	r5	r6	r7	r0	r1	r2
+sparc/32	o0	o1	o2	o3	o4	o5	-
+sparc/64	o0	o1	o2	o3	o4	o5	-
+tile	R00	R01	R02	R03	R04	R05	-
+x86-64	rdi	rsi	rdx	r10	r8	r9	-
+x32	rdi	rsi	rdx	r10	r8	r9	-
+xtensa	a6	a3	a4	a5	a8	a9	-
+.TE
+.P
+Notes:
+.IP \[bu] 3
+The mips/o32 system call convention passes
+arguments 5 through 8 on the user stack.
+.if t \{\
+.in
+.ft P
+\}
+.P
+Note that these tables don't cover the entire calling convention\[em]some
+architectures may indiscriminately clobber other registers not listed here.
+.SH EXAMPLES
+.\" SRC BEGIN (syscall.c)
+.EX
+#define _GNU_SOURCE
+#include <signal.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+int
+main(void)
+{
+    pid_t tid;
+\&
+    tid = syscall(SYS_gettid);
+    syscall(SYS_tgkill, getpid(), tid, SIGHUP);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR _syscall (2),
+.BR intro (2),
+.BR syscalls (2),
+.BR errno (3),
+.BR vdso (7)
diff --git a/man/man2/syscalls.2 b/man/man2/syscalls.2
new file mode 100644
index 000000000..7a7d6d730
--- /dev/null
+++ b/man/man2/syscalls.2
@@ -0,0 +1,1172 @@
+'\" t
+.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" with some input from Stepan Kasal <kasal@ucw.cz>
+.\"
+.\" Some content retained from an earlier version of this page:
+.\" Copyright (C) 1998 Andries Brouwer (aeb@cwi.nl)
+.\" Modifications for 2.2 and 2.4 Copyright (C) 2002 Ian Redfern
+.\" <redferni@logica.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH syscalls 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+syscalls \- Linux system calls
+.SH SYNOPSIS
+.nf
+Linux system calls.
+.fi
+.SH DESCRIPTION
+The system call is the fundamental interface between an application
+and the Linux kernel.
+.SS System calls and library wrapper functions
+System calls are generally not invoked directly,
+but rather via wrapper functions in glibc (or perhaps some other library).
+For details of direct invocation of a system call, see
+.BR intro (2).
+Often, but not always, the name of the wrapper function is the same
+as the name of the system call that it invokes.
+For example, glibc contains a function
+.BR chdir ()
+which invokes the underlying "chdir" system call.
+.P
+Often the glibc wrapper function is quite thin, doing little work
+other than copying arguments to the right registers
+before invoking the system call,
+and then setting
+.I errno
+appropriately after the system call has returned.
+(These are the same steps that are performed by
+.BR syscall (2),
+which can be used to invoke system calls
+for which no wrapper function is provided.)
+Note: system calls indicate a failure by returning a negative error
+number to the caller on architectures without a separate error register/flag,
+as noted in
+.BR syscall (2);
+when this happens,
+the wrapper function negates the returned error number
+(to make it positive), copies it to
+.IR errno ,
+and returns \-1 to the caller of the wrapper.
+.P
+Sometimes, however, the wrapper function does some extra work
+before invoking the system call.
+For example, nowadays there are (for reasons described below) two
+related system calls,
+.BR truncate (2)
+and
+.BR truncate64 (2),
+and the glibc
+.BR truncate ()
+wrapper function checks which of those system calls
+are provided by the kernel and determines which should be employed.
+.SS System call list
+Below is a list of the Linux system calls.
+In the list, the
+.I Kernel
+column indicates the kernel version
+for those system calls that were new in Linux 2.2,
+or have appeared since that kernel version.
+Note the following points:
+.IP \[bu] 3
+Where no kernel version is indicated,
+the system call appeared in Linux 1.0 or earlier.
+.IP \[bu]
+Where a system call is marked "1.2"
+this means the system call probably appeared in a Linux 1.1.x kernel version,
+and first appeared in a stable kernel with 1.2.
+(Development of the Linux 1.2 kernel was initiated from a branch of
+Linux 1.0.6 via the Linux 1.1.x unstable kernel series.)
+.IP \[bu]
+Where a system call is marked "2.0"
+this means the system call probably appeared in a Linux 1.3.x kernel version,
+and first appeared in a stable kernel with Linux 2.0.
+(Development of the Linux 2.0 kernel was initiated from a branch of
+Linux 1.2.x, somewhere around Linux 1.2.10,
+via the Linux 1.3.x unstable kernel series.)
+.\" Was Linux 2.0 started from a branch of Linux 1.2.10?
+.\" At least from the timestamps of the tarballs of
+.\" of Linux 1.2.10 and Linux 1.3.0, that's how it looks, but in
+.\" fact the diff doesn't seem very clear, the
+.\" Linux 1.3.0 .tar.bz is much bigger (2.0 MB) than the
+.\" Linux 1.2.10 .tar.bz2 (1.8 MB), and AEB points out the
+.\" timestamps of some files in Linux 1.3.0 seem to be older
+.\" than those in Linux 1.2.10.  All of this suggests
+.\" that there might not have been a clean branch point.
+.IP \[bu]
+Where a system call is marked "2.2"
+this means the system call probably appeared in a Linux 2.1.x kernel version,
+and first appeared in a stable kernel with Linux 2.2.0.
+(Development of the Linux 2.2 kernel was initiated from a branch of
+Linux 2.0.21 via the Linux 2.1.x unstable kernel series.)
+.IP \[bu]
+Where a system call is marked "2.4"
+this means the system call probably appeared in a Linux 2.3.x kernel version,
+and first appeared in a stable kernel with Linux 2.4.0.
+(Development of the Linux 2.4 kernel was initiated from a branch of
+Linux 2.2.8 via the Linux 2.3.x unstable kernel series.)
+.IP \[bu]
+Where a system call is marked "2.6"
+this means the system call probably appeared in a Linux 2.5.x kernel version,
+and first appeared in a stable kernel with Linux 2.6.0.
+(Development of Linux 2.6 was initiated from a branch
+of Linux 2.4.15 via the Linux 2.5.x unstable kernel series.)
+.IP \[bu]
+Starting with Linux 2.6.0, the development model changed,
+and new system calls may appear in each Linux 2.6.x release.
+In this case, the exact version number where the system call appeared
+is shown.
+This convention continues with the Linux 3.x kernel series,
+which followed on from Linux 2.6.39; and the Linux 4.x kernel series,
+which followed on from Linux 3.19; and the Linux 5.x kernel series,
+which followed on from Linux 4.20; and the Linux 6.x kernel series,
+which followed on from Linux 5.19.
+.IP \[bu]
+In some cases, a system call was added to a stable kernel
+series after it branched from the previous stable kernel
+series, and then backported into the earlier stable kernel series.
+For example some system calls that appeared in Linux 2.6.x were also backported
+into a Linux 2.4.x release after Linux 2.4.15.
+When this is so, the version where the system call appeared
+in both of the major kernel series is listed.
+.P
+The list of system calls that are available as at Linux 5.14
+(or in a few cases only on older kernels) is as follows:
+.P
+.\"
+.\" Looking at scripts/checksyscalls.sh in the kernel source is
+.\" instructive about x86 specifics.
+.\"
+.TS
+Lb Lb Lb
+L2 L  L.
+System call	Kernel	Notes
+_
+\fB_llseek\fP(2)	1.2
+\fB_newselect\fP(2)	2.0
+\fB_sysctl\fP(2)	2.0	Removed in 5.5
+\fBaccept\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBaccept4\fP(2)	2.6.28
+\fBaccess\fP(2)	1.0
+\fBacct\fP(2)	1.0
+\fBadd_key\fP(2)	2.6.10
+\fBadjtimex\fP(2)	1.0
+\fBalarm\fP(2)	1.0
+\fBalloc_hugepages\fP(2)	2.5.36	Removed in 2.5.44
+.\" 4adeefe161a74369e44cc8e663f240ece0470dc3
+\fBarc_gettls\fP(2)	3.9	ARC only
+\fBarc_settls\fP(2)	3.9	ARC only
+.\" 91e040a79df73d371f70792f30380d4e44805250
+\fBarc_usr_cmpxchg\fP(2)	4.9	ARC only
+.\" x86: 79170fda313ed5be2394f87aa2a00d597f8ed4a1
+\fBarch_prctl\fP(2)	2.6	T{
+x86_64, x86 since 4.12
+T}
+.\" 9674cdc74d63f346870943ef966a034f8c71ee57
+\fBatomic_barrier\fP(2)	2.6.34	m68k only
+\fBatomic_cmpxchg_32\fP(2)	2.6.34	m68k only
+\fBbdflush\fP(2)	1.2	T{
+Deprecated (does nothing)
+since 2.6
+T}
+\fBbind\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBbpf\fP(2)	3.18
+\fBbrk\fP(2)	1.0
+\fBbreakpoint\fP(2)	2.2	T{
+ARM OABI only, defined with
+\fB__ARM_NR\fP prefix
+T}
+\fBcacheflush\fP(2)	1.2	Not on x86
+\fBcapget\fP(2)	2.2
+\fBcapset\fP(2)	2.2
+\fBchdir\fP(2)	1.0
+\fBchmod\fP(2)	1.0
+\fBchown\fP(2)	2.2	T{
+See \fBchown\fP(2) for
+version details
+T}
+\fBchown32\fP(2)	2.4
+\fBchroot\fP(2)	1.0
+\fBclock_adjtime\fP(2)	2.6.39
+\fBclock_getres\fP(2)	2.6
+\fBclock_gettime\fP(2)	2.6
+\fBclock_nanosleep\fP(2)	2.6
+\fBclock_settime\fP(2)	2.6
+\fBclone2\fP(2)	2.4	IA-64 only
+\fBclone\fP(2)	1.0
+\fBclone3\fP(2)	5.3
+\fBclose\fP(2)	1.0
+\fBclose_range\fP(2)	5.9
+.\" .\" dcef1f634657dabe7905af3ccda12cf7f0b6fcc1
+.\" .\" cc20d42986d5807cbe4f5c7c8e3dab2e59ea0db3
+.\" .\" db695c0509d6ec9046ee5e4c520a19fa17d9fce2
+.\" \fBcmpxchg\fP(2)	2.6.12	T{
+.\" ARM, syscall constant never was
+.\" exposed to user space, in-kernel
+.\" definition had \fB__ARM_NR\fP prefix,
+.\" removed in 4.4
+.\" T}
+.\" 867e359b97c970a60626d5d76bbe2a8fadbf38fb
+.\" bb9d812643d8a121df7d614a2b9c60193a92deb0
+\fBconnect\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBcopy_file_range\fP(2)	4.5
+\fBcreat\fP(2)	1.0
+\fBcreate_module\fP(2)	1.0	Removed in 2.6
+\fBdelete_module\fP(2)	1.0
+.\" 1394f03221790a988afc3e4b3cb79f2e477246a9
+.\" 4ba66a9760722ccbb691b8f7116cad2f791cca7b
+\fBdup\fP(2)	1.0
+\fBdup2\fP(2)	1.0
+\fBdup3\fP(2)	2.6.27
+\fBepoll_create\fP(2)	2.6
+\fBepoll_create1\fP(2)	2.6.27
+\fBepoll_ctl\fP(2)	2.6
+\fBepoll_pwait\fP(2)	2.6.19
+\fBepoll_pwait2\fP(2)	5.11
+\fBepoll_wait\fP(2)	2.6
+\fBeventfd\fP(2)	2.6.22
+\fBeventfd2\fP(2)	2.6.27
+\fBexecv\fP(2)	2.0	T{
+SPARC/SPARC64 only, for
+compatibility with SunOS
+T}
+\fBexecve\fP(2)	1.0
+\fBexecveat\fP(2)	3.19
+\fBexit\fP(2)	1.0
+\fBexit_group\fP(2)	2.6
+\fBfaccessat\fP(2)	2.6.16
+\fBfaccessat2\fP(2)	5.8
+\fBfadvise64\fP(2)	2.6
+.\" Implements \fBposix_fadvise\fP(2)
+\fBfadvise64_64\fP(2)	2.6
+\fBfallocate\fP(2)	2.6.23
+\fBfanotify_init\fP(2)	2.6.37
+\fBfanotify_mark\fP(2)	2.6.37
+.\" The fanotify calls were added in Linux 2.6.36,
+.\" but disabled while the API was finalized.
+\fBfchdir\fP(2)	1.0
+\fBfchmod\fP(2)	1.0
+\fBfchmodat\fP(2)	2.6.16
+\fBfchown\fP(2)	1.0
+\fBfchown32\fP(2)	2.4
+\fBfchownat\fP(2)	2.6.16
+\fBfcntl\fP(2)	1.0
+\fBfcntl64\fP(2)	2.4
+\fBfdatasync\fP(2)	2.0
+\fBfgetxattr\fP(2)	2.6; 2.4.18
+\fBfinit_module\fP(2)	3.8
+\fBflistxattr\fP(2)	2.6; 2.4.18
+\fBflock\fP(2)	2.0
+\fBfork\fP(2)	1.0
+\fBfree_hugepages\fP(2)	2.5.36	Removed in 2.5.44
+\fBfremovexattr\fP(2)	2.6; 2.4.18
+\fBfsconfig\fP(2)	5.2
+\fBfsetxattr\fP(2)	2.6; 2.4.18
+\fBfsmount\fP(2)	5.2
+\fBfsopen\fP(2)	5.2
+\fBfspick\fP(2)	5.2
+\fBfstat\fP(2)	1.0
+\fBfstat64\fP(2)	2.4
+\fBfstatat64\fP(2)	2.6.16
+\fBfstatfs\fP(2)	1.0
+\fBfstatfs64\fP(2)	2.6
+\fBfsync\fP(2)	1.0
+\fBftruncate\fP(2)	1.0
+\fBftruncate64\fP(2)	2.4
+\fBfutex\fP(2)	2.6
+\fBfutimesat\fP(2)	2.6.16
+\fBget_kernel_syms\fP(2)	1.0	Removed in 2.6
+\fBget_mempolicy\fP(2)	2.6.6
+\fBget_robust_list\fP(2)	2.6.17
+\fBget_thread_area\fP(2)	2.6
+.\" 8fcd6c45f5a65621ec809b7866a3623e9a01d4ed
+\fBget_tls\fP(2)	4.15	T{
+ARM OABI only, has
+\fB__ARM_NR\fP prefix
+T}
+\fBgetcpu\fP(2)	2.6.19
+\fBgetcwd\fP(2)	2.2
+\fBgetdents\fP(2)	2.0
+\fBgetdents64\fP(2)	2.4
+.\" parisc: 863722e856e64dae0e252b6bb546737c6c5626ce
+\fBgetdomainname\fP(2)	2.2	T{
+SPARC, SPARC64; available
+as \fBosf_getdomainname\fP(2)
+on Alpha since Linux 2.0
+T}
+.\" ec98c6b9b47df6df1c1fa6cf3d427414f8c2cf16
+\fBgetdtablesize\fP(2)	2.0	T{
+SPARC (removed in 2.6.26),
+available on Alpha as
+\fBosf_getdtablesize\fP(2)
+T}
+\fBgetegid\fP(2)	1.0
+\fBgetegid32\fP(2)	2.4
+\fBgeteuid\fP(2)	1.0
+\fBgeteuid32\fP(2)	2.4
+\fBgetgid\fP(2)	1.0
+\fBgetgid32\fP(2)	2.4
+\fBgetgroups\fP(2)	1.0
+\fBgetgroups32\fP(2)	2.4
+.\" SPARC removal: ec98c6b9b47df6df1c1fa6cf3d427414f8c2cf16
+\fBgethostname\fP(2)	2.0	T{
+Alpha, was available on
+SPARC up to Linux 2.6.26
+T}
+\fBgetitimer\fP(2)	1.0
+\fBgetpeername\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBgetpagesize\fP(2)	2.0	T{
+Alpha, SPARC/SPARC64 only
+T}
+\fBgetpgid\fP(2)	1.0
+\fBgetpgrp\fP(2)	1.0
+\fBgetpid\fP(2)	1.0
+\fBgetppid\fP(2)	1.0
+\fBgetpriority\fP(2)	1.0
+\fBgetrandom\fP(2)	3.17
+\fBgetresgid\fP(2)	2.2
+\fBgetresgid32\fP(2)	2.4
+\fBgetresuid\fP(2)	2.2
+\fBgetresuid32\fP(2)	2.4
+\fBgetrlimit\fP(2)	1.0
+\fBgetrusage\fP(2)	1.0
+\fBgetsid\fP(2)	2.0
+\fBgetsockname\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBgetsockopt\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBgettid\fP(2)	2.4.11
+\fBgettimeofday\fP(2)	1.0
+\fBgetuid\fP(2)	1.0
+\fBgetuid32\fP(2)	2.4
+\fBgetunwind\fP(2)	2.4.8	T{
+IA-64 only; deprecated
+T}
+\fBgetxattr\fP(2)	2.6; 2.4.18
+\fBgetxgid\fP(2)	2.0	T{
+Alpha only; see NOTES
+T}
+\fBgetxpid\fP(2)	2.0	T{
+Alpha only; see NOTES
+T}
+\fBgetxuid\fP(2)	2.0	T{
+Alpha only; see NOTES
+T}
+\fBinit_module\fP(2)	1.0
+\fBinotify_add_watch\fP(2)	2.6.13
+\fBinotify_init\fP(2)	2.6.13
+\fBinotify_init1\fP(2)	2.6.27
+\fBinotify_rm_watch\fP(2)	2.6.13
+\fBio_cancel\fP(2)	2.6
+\fBio_destroy\fP(2)	2.6
+\fBio_getevents\fP(2)	2.6
+\fBio_pgetevents\fP(2)	4.18
+\fBio_setup\fP(2)	2.6
+\fBio_submit\fP(2)	2.6
+\fBio_uring_enter\fP(2)	5.1
+\fBio_uring_register\fP(2)	5.1
+\fBio_uring_setup\fP(2)	5.1
+\fBioctl\fP(2)	1.0
+\fBioperm\fP(2)	1.0
+\fBiopl\fP(2)	1.0
+\fBioprio_get\fP(2)	2.6.13
+\fBioprio_set\fP(2)	2.6.13
+\fBipc\fP(2)	1.0
+.\" Implements System V IPC calls
+\fBkcmp\fP(2)	3.5
+\fBkern_features\fP(2)	3.7	SPARC64 only
+.\" FIXME . document kern_features():
+.\" commit 517ffce4e1a03aea979fe3a18a3dd1761a24fafb
+\fBkexec_file_load\fP(2)	3.17
+\fBkexec_load\fP(2)	2.6.13
+.\" The entry in the syscall table was reserved starting in 2.6.7
+.\" Was named sys_kexec_load() from 2.6.7 to 2.6.16
+\fBkeyctl\fP(2)	2.6.10
+\fBkill\fP(2)	1.0
+\fBlandlock_add_rule\fP(2)	5.13
+\fBlandlock_create_ruleset\fP(2)	5.13
+\fBlandlock_restrict_self\fP(2)	5.13
+\fBlchown\fP(2)	1.0	T{
+See \fBchown\fP(2) for
+version details
+T}
+\fBlchown32\fP(2)	2.4
+\fBlgetxattr\fP(2)	2.6; 2.4.18
+\fBlink\fP(2)	1.0
+\fBlinkat\fP(2)	2.6.16
+\fBlisten\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBlistxattr\fP(2)	2.6; 2.4.18
+\fBllistxattr\fP(2)	2.6; 2.4.18
+\fBlookup_dcookie\fP(2)	2.6
+\fBlremovexattr\fP(2)	2.6; 2.4.18
+\fBlseek\fP(2)	1.0
+\fBlsetxattr\fP(2)	2.6; 2.4.18
+\fBlstat\fP(2)	1.0
+\fBlstat64\fP(2)	2.4
+\fBmadvise\fP(2)	2.4
+\fBmbind\fP(2)	2.6.6
+\fBmemory_ordering\fP(2)	2.2	SPARC64 only
+.\" 26025bbfbba33a9425be1b89eccb4664ea4c17b6
+.\" bb6fb6dfcc17cddac11ac295861f7608194447a7
+\fBmembarrier\fP(2)	3.17
+\fBmemfd_create\fP(2)	3.17
+\fBmemfd_secret\fP(2)	5.14
+\fBmigrate_pages\fP(2)	2.6.16
+\fBmincore\fP(2)	2.4
+\fBmkdir\fP(2)	1.0
+\fBmkdirat\fP(2)	2.6.16
+\fBmknod\fP(2)	1.0
+\fBmknodat\fP(2)	2.6.16
+\fBmlock\fP(2)	2.0
+\fBmlock2\fP(2)	4.4
+\fBmlockall\fP(2)	2.0
+\fBmmap\fP(2)	1.0
+\fBmmap2\fP(2)	2.4
+\fBmodify_ldt\fP(2)	1.0
+\fBmount\fP(2)	1.0
+\fBmove_mount\fP(2)	5.2
+\fBmove_pages\fP(2)	2.6.18
+\fBmprotect\fP(2)	1.0
+\fBmq_getsetattr\fP(2)	2.6.6
+.\" Implements \fBmq_getattr\fP(3) and \fBmq_setattr\fP(3)
+\fBmq_notify\fP(2)	2.6.6
+\fBmq_open\fP(2)	2.6.6
+\fBmq_timedreceive\fP(2)	2.6.6
+\fBmq_timedsend\fP(2)	2.6.6
+\fBmq_unlink\fP(2)	2.6.6
+\fBmremap\fP(2)	2.0
+\fBmsgctl\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBmsgget\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBmsgrcv\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBmsgsnd\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBmsync\fP(2)	2.0
+.\" \fBmultiplexer\fP(2)	??	__NR_multiplexer reserved on
+.\"		PowerPC, but unimplemented?
+\fBmunlock\fP(2)	2.0
+\fBmunlockall\fP(2)	2.0
+\fBmunmap\fP(2)	1.0
+\fBname_to_handle_at\fP(2)	2.6.39
+\fBnanosleep\fP(2)	2.0
+.\" 5590ff0d5528b60153c0b4e7b771472b5a95e297
+\fBnewfstatat\fP(2)	2.6.16	T{
+See \fBstat\fP(2)
+T}
+\fBnfsservctl\fP(2)	2.2	Removed in 3.1
+\fBnice\fP(2)	1.0
+\fBold_adjtimex\fP(2)	2.0	T{
+Alpha only; see NOTES
+T}
+\fBold_getrlimit\fP(2)	2.4	T{
+Old variant of \fBgetrlimit\fP(2)
+that used a different value
+for \fBRLIM_INFINITY\fP
+T}
+\fBoldfstat\fP(2)	1.0
+\fBoldlstat\fP(2)	1.0
+\fBoldolduname\fP(2)	1.0
+\fBoldstat\fP(2)	1.0
+\fBoldumount\fP(2)	2.4.116	T{
+Name of the old \fBumount\fP(2)
+syscall on Alpha
+T}
+\fBolduname\fP(2)	1.0
+\fBopen\fP(2)	1.0
+\fBopen_by_handle_at\fP(2)	2.6.39
+\fBopen_tree\fP(2)	5.2
+\fBopenat\fP(2)	2.6.16
+\fBopenat2\fP(2)	5.6
+.\" 9d02a4283e9ce4e9ca11ff00615bdacdb0515a1a
+\fBor1k_atomic\fP(2)	3.1	T{
+OpenRISC 1000 only
+T}
+\fBpause\fP(2)	1.0
+\fBpciconfig_iobase\fP(2)	2.2.15; 2.4	Not on x86
+.\" Alpha, PowerPC, ARM; not x86
+\fBpciconfig_read\fP(2)	2.0.26; 2.2	Not on x86
+.\" , PowerPC, ARM; not x86
+\fBpciconfig_write\fP(2)	2.0.26; 2.2	Not on x86
+.\" , PowerPC, ARM; not x86
+\fBperf_event_open\fP(2)	2.6.31	T{
+Was perf_counter_open() in
+2.6.31; renamed in 2.6.32
+T}
+\fBpersonality\fP(2)	1.2
+\fBperfctr\fP(2)	2.2	T{
+SPARC only; removed in 2.6.34
+T}
+.\"	commit c7d5a0050773e98d1094eaa9f2a1a793fafac300 removed perfctr()
+\fBperfmonctl\fP(2)	2.4	IA-64 only; removed in 5.10
+\fBpidfd_getfd\fP(2)	5.6
+\fBpidfd_send_signal\fP(2)	5.1
+\fBpidfd_open\fP(2)	5.3
+\fBpipe\fP(2)	1.0
+\fBpipe2\fP(2)	2.6.27
+\fBpivot_root\fP(2)	2.4
+\fBpkey_alloc\fP(2)	4.8
+\fBpkey_free\fP(2)	4.8
+\fBpkey_mprotect\fP(2)	4.8
+\fBpoll\fP(2)	2.0.36; 2.2
+\fBppoll\fP(2)	2.6.16
+\fBprctl\fP(2)	2.2
+\fBpread64\fP(2)		T{
+Added as "pread" in 2.2;
+renamed "pread64" in 2.6
+T}
+\fBpreadv\fP(2)	2.6.30
+\fBpreadv2\fP(2)	4.6
+\fBprlimit64\fP(2)	2.6.36
+\fBprocess_madvise\fP(2)	5.10
+\fBprocess_vm_readv\fP(2)	3.2
+\fBprocess_vm_writev\fP(2)	3.2
+\fBpselect6\fP(2)	2.6.16
+.\" Implements \fBpselect\fP(2)
+\fBptrace\fP(2)	1.0
+\fBpwrite64\fP(2)		T{
+Added as "pwrite" in 2.2;
+renamed "pwrite64" in 2.6
+T}
+\fBpwritev\fP(2)	2.6.30
+\fBpwritev2\fP(2)	4.6
+\fBquery_module\fP(2)	2.2	Removed in 2.6
+\fBquotactl\fP(2)	1.0
+\fBquotactl_fd\fP(2)	5.14
+\fBread\fP(2)	1.0
+\fBreadahead\fP(2)	2.4.13
+\fBreaddir\fP(2)	1.0
+.\" Supersedes \fBgetdents\fP(2)
+\fBreadlink\fP(2)	1.0
+\fBreadlinkat\fP(2)	2.6.16
+\fBreadv\fP(2)	2.0
+\fBreboot\fP(2)	1.0
+\fBrecv\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBrecvfrom\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBrecvmsg\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBrecvmmsg\fP(2)	2.6.33
+\fBremap_file_pages\fP(2)	2.6	T{
+Deprecated since 3.16
+T}
+\fBremovexattr\fP(2)	2.6; 2.4.18
+\fBrename\fP(2)	1.0
+\fBrenameat\fP(2)	2.6.16
+\fBrenameat2\fP(2)	3.15
+\fBrequest_key\fP(2)	2.6.10
+\fBrestart_syscall\fP(2)	2.6
+.\" 921ebd8f2c081b3cf6c3b29ef4103eef3ff26054
+\fBriscv_flush_icache\fP(2)	4.15	RISC-V only
+\fBrmdir\fP(2)	1.0
+\fBrseq\fP(2)	4.18
+\fBrt_sigaction\fP(2)	2.2
+\fBrt_sigpending\fP(2)	2.2
+\fBrt_sigprocmask\fP(2)	2.2
+\fBrt_sigqueueinfo\fP(2)	2.2
+\fBrt_sigreturn\fP(2)	2.2
+\fBrt_sigsuspend\fP(2)	2.2
+\fBrt_sigtimedwait\fP(2)	2.2
+\fBrt_tgsigqueueinfo\fP(2)	2.6.31
+\fBrtas\fP(2)	2.6.2	T{
+PowerPC/PowerPC64 only
+T}
+\fBs390_runtime_instr\fP(2)	3.7	s390 only
+\fBs390_pci_mmio_read\fP(2)	3.19	s390 only
+\fBs390_pci_mmio_write\fP(2)	3.19	s390 only
+\fBs390_sthyi\fP(2)	4.15	s390 only
+\fBs390_guarded_storage\fP(2)	4.12	s390 only
+\fBsched_get_affinity\fP(2)	2.6	T{
+Name of
+.BR \%sched_getaffinity (2)
+on SPARC and SPARC64
+T}
+\fBsched_get_priority_max\fP(2)	2.0
+\fBsched_get_priority_min\fP(2)	2.0
+\fBsched_getaffinity\fP(2)	2.6
+\fBsched_getattr\fP(2)	3.14
+\fBsched_getparam\fP(2)	2.0
+\fBsched_getscheduler\fP(2)	2.0
+\fBsched_rr_get_interval\fP(2)	2.0
+\fBsched_set_affinity\fP(2)	2.6	T{
+Name of
+.BR \%sched_setaffinity (2)
+on SPARC and SPARC64
+T}
+\fBsched_setaffinity\fP(2)	2.6
+\fBsched_setattr\fP(2)	3.14
+\fBsched_setparam\fP(2)	2.0
+\fBsched_setscheduler\fP(2)	2.0
+\fBsched_yield\fP(2)	2.0
+\fBseccomp\fP(2)	3.17
+\fBselect\fP(2)	1.0
+\fBsemctl\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBsemget\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBsemop\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBsemtimedop\fP(2)	2.6; 2.4.22
+\fBsend\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBsendfile\fP(2)	2.2
+\fBsendfile64\fP(2)	2.6; 2.4.19
+\fBsendmmsg\fP(2)	3.0
+\fBsendmsg\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBsendto\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBset_mempolicy\fP(2)	2.6.6
+\fBset_robust_list\fP(2)	2.6.17
+\fBset_thread_area\fP(2)	2.6
+\fBset_tid_address\fP(2)	2.6
+\fBset_tls\fP(2)	2.6.11	T{
+ARM OABI/EABI only (constant
+has \fB__ARM_NR\fP prefix)
+T}
+.\" \fBsetaltroot\fP(2)	2.6.10	T{
+.\" Removed in 2.6.11, exposed one
+.\" of implementation details of
+.\" \fBpersonality\fP(2) (creating an
+.\" alternative root, precursor of
+.\" mount namespaces) to user space.
+.\" T}
+.\" See http://lkml.org/lkml/2005/8/1/83
+.\" "[PATCH] remove sys_set_zone_reclaim()"
+\fBsetdomainname\fP(2)	1.0
+\fBsetfsgid\fP(2)	1.2
+\fBsetfsgid32\fP(2)	2.4
+\fBsetfsuid\fP(2)	1.2
+\fBsetfsuid32\fP(2)	2.4
+\fBsetgid\fP(2)	1.0
+\fBsetgid32\fP(2)	2.4
+\fBsetgroups\fP(2)	1.0
+\fBsetgroups32\fP(2)	2.4
+.\" arch/alpha/include/asm/core_lca.h
+\fBsethae\fP(2)	2.0	T{
+Alpha only; see NOTES
+T}
+\fBsethostname\fP(2)	1.0
+\fBsetitimer\fP(2)	1.0
+\fBsetns\fP(2)	3.0
+\fBsetpgid\fP(2)	1.0
+\fBsetpgrp\fP(2)	2.0	T{
+Alternative name for \fBsetpgid\fP(2) on Alpha
+T}
+\fBsetpriority\fP(2)	1.0
+\fBsetregid\fP(2)	1.0
+\fBsetregid32\fP(2)	2.4
+\fBsetresgid\fP(2)	2.2
+\fBsetresgid32\fP(2)	2.4
+\fBsetresuid\fP(2)	2.2
+\fBsetresuid32\fP(2)	2.4
+\fBsetreuid\fP(2)	1.0
+\fBsetreuid32\fP(2)	2.4
+\fBsetrlimit\fP(2)	1.0
+\fBsetsid\fP(2)	1.0
+\fBsetsockopt\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBsettimeofday\fP(2)	1.0
+\fBsetuid\fP(2)	1.0
+\fBsetuid32\fP(2)	2.4
+\fBsetup\fP(2)	1.0	Removed in 2.2
+\fBsetxattr\fP(2)	2.6; 2.4.18
+\fBsgetmask\fP(2)	1.0
+\fBshmat\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBshmctl\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBshmdt\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBshmget\fP(2)	2.0	T{
+See notes on \fBipc\fP(2)
+T}
+\fBshutdown\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBsigaction\fP(2)	1.0
+\fBsigaltstack\fP(2)	2.2
+\fBsignal\fP(2)	1.0
+\fBsignalfd\fP(2)	2.6.22
+\fBsignalfd4\fP(2)	2.6.27
+\fBsigpending\fP(2)	1.0
+\fBsigprocmask\fP(2)	1.0
+\fBsigreturn\fP(2)	1.0
+\fBsigsuspend\fP(2)	1.0
+\fBsocket\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+\fBsocketcall\fP(2)	1.0
+.\" Implements BSD socket calls
+\fBsocketpair\fP(2)	2.0	T{
+See notes on \fBsocketcall\fP(2)
+T}
+.\" 5a0015d62668e64c8b6e02e360fbbea121bfd5e6
+\fBspill\fP(2)	2.6.13	Xtensa only
+\fBsplice\fP(2)	2.6.17
+\fBspu_create\fP(2)	2.6.16	T{
+PowerPC/PowerPC64 only
+T}
+\fBspu_run\fP(2)	2.6.16	T{
+PowerPC/PowerPC64 only
+T}
+\fBssetmask\fP(2)	1.0
+\fBstat\fP(2)	1.0
+\fBstat64\fP(2)	2.4
+\fBstatfs\fP(2)	1.0
+\fBstatfs64\fP(2)	2.6
+\fBstatx\fP(2)	4.11
+\fBstime\fP(2)	1.0
+\fBsubpage_prot\fP(2)	2.6.25	T{
+PowerPC/PowerPC64 only
+T}
+\fBswapcontext\fP(2)	2.6.3	T{
+PowerPC/PowerPC64 only
+T}
+.\" 529d235a0e190ded1d21ccc80a73e625ebcad09b
+\fBswitch_endian\fP(2)	4.1	PowerPC64 only
+\fBswapoff\fP(2)	1.0
+\fBswapon\fP(2)	1.0
+\fBsymlink\fP(2)	1.0
+\fBsymlinkat\fP(2)	2.6.16
+\fBsync\fP(2)	1.0
+\fBsync_file_range\fP(2)	2.6.17
+\fBsync_file_range2\fP(2)	2.6.22
+.\" PowerPC, ARM, tile
+.\" First appeared on ARM, as arm_sync_file_range(), but later renamed
+.\" \fBsys_debug_setcontext\fP(2)	???	PowerPC if CONFIG_PPC32
+\fBsyncfs\fP(2)	2.6.39
+\fBsys_debug_setcontext\fP(2)	2.6.11	PowerPC only
+\fBsyscall\fP(2)	1.0	T{
+Still available on ARM OABI
+and MIPS O32 ABI
+T}
+\fBsysfs\fP(2)	1.2
+\fBsysinfo\fP(2)	1.0
+\fBsyslog\fP(2)	1.0
+.\" glibc interface is \fBklogctl\fP(3)
+\fBsysmips\fP(2)	2.6.0	MIPS only
+\fBtee\fP(2)	2.6.17
+\fBtgkill\fP(2)	2.6
+\fBtime\fP(2)	1.0
+\fBtimer_create\fP(2)	2.6
+\fBtimer_delete\fP(2)	2.6
+\fBtimer_getoverrun\fP(2)	2.6
+\fBtimer_gettime\fP(2)	2.6
+\fBtimer_settime\fP(2)	2.6
+.\" .\" b215e283992899650c4271e7385c79e26fb9a88e
+.\" .\" 4d672e7ac79b5ec5cdc90e450823441e20464691
+.\" \fBtimerfd\fP(2)	2.6.22	T{
+.\" Old timerfd interface,
+.\" removed in 2.6.25
+.\" T}
+\fBtimerfd_create\fP(2)	2.6.25
+\fBtimerfd_gettime\fP(2)	2.6.25
+\fBtimerfd_settime\fP(2)	2.6.25
+\fBtimes\fP(2)	1.0
+\fBtkill\fP(2)	2.6; 2.4.22
+\fBtruncate\fP(2)	1.0
+\fBtruncate64\fP(2)	2.4
+\fBugetrlimit\fP(2)	2.4
+\fBumask\fP(2)	1.0
+\fBumount\fP(2)	1.0
+.\" sys_oldumount() -- __NR_umount
+\fBumount2\fP(2)	2.2
+.\" sys_umount() -- __NR_umount2
+\fBuname\fP(2)	1.0
+\fBunlink\fP(2)	1.0
+\fBunlinkat\fP(2)	2.6.16
+\fBunshare\fP(2)	2.6.16
+\fBuselib\fP(2)	1.0
+\fBustat\fP(2)	1.0
+\fBuserfaultfd\fP(2)	4.3
+\fBusr26\fP(2)	2.4.8.1	ARM OABI only
+\fBusr32\fP(2)	2.4.8.1	ARM OABI only
+\fButime\fP(2)	1.0
+\fButimensat\fP(2)	2.6.22
+\fButimes\fP(2)	2.2
+\fButrap_install\fP(2)	2.2	SPARC64 only
+.\" FIXME . document utrap_install()
+.\" There's a man page for Solaris 5.11
+\fBvfork\fP(2)	2.2
+\fBvhangup\fP(2)	1.0
+\fBvm86old\fP(2)	1.0	T{
+Was "vm86"; renamed in
+2.0.28/2.2
+T}
+\fBvm86\fP(2)	2.0.28; 2.2
+\fBvmsplice\fP(2)	2.6.17
+\fBwait4\fP(2)	1.0
+\fBwaitid\fP(2)	2.6.10
+\fBwaitpid\fP(2)	1.0
+\fBwrite\fP(2)	1.0
+\fBwritev\fP(2)	2.0
+.\" 5a0015d62668e64c8b6e02e360fbbea121bfd5e6
+\fBxtensa\fP(2)	2.6.13	Xtensa only
+.TE
+.P
+On many platforms, including x86-32, socket calls are all multiplexed
+(via glibc wrapper functions) through
+.BR socketcall (2)
+and similarly System\ V IPC calls are multiplexed through
+.BR ipc (2).
+.P
+Although slots are reserved for them in the system call table,
+the following system calls are not implemented in the standard kernel:
+.BR afs_syscall (2), \" __NR_afs_syscall is 53 on Linux 2.6.22/i386
+.BR break (2),       \" __NR_break is 17 on Linux 2.6.22/i386
+.BR ftime (2),       \" __NR_ftime is 35 on Linux 2.6.22/i386
+.BR getpmsg (2),     \" __NR_getpmsg is 188 on Linux 2.6.22/i386
+.BR gtty (2),        \" __NR_gtty is 32 on Linux 2.6.22/i386
+.BR idle (2),        \" __NR_idle is 112 on Linux 2.6.22/i386
+.BR lock (2),        \" __NR_lock is 53 on Linux 2.6.22/i386
+.BR madvise1 (2),    \" __NR_madvise1 is 219 on Linux 2.6.22/i386
+.BR mpx (2),         \" __NR_mpx is 66 on Linux 2.6.22/i386
+.BR phys (2),        \" Slot has been reused
+.BR prof (2),        \" __NR_prof is 44 on Linux 2.6.22/i386
+.BR profil (2),      \" __NR_profil is 98 on Linux 2.6.22/i386
+.BR putpmsg (2),     \" __NR_putpmsg is 189 on Linux 2.6.22/i386
+.\" __NR_security is 223 on Linux 2.4/i386; absent on 2.6/i386, present
+.\" on a couple of 2.6 architectures
+.BR security (2),    \" __NR_security is 223 on Linux 2.4/i386
+.\" The security call is for future use.
+.BR stty (2),        \" __NR_stty is 31 on Linux 2.6.22/i386
+.BR tuxcall (2),     \" __NR_tuxcall is 184 on x86_64, also on PPC and alpha
+.BR ulimit (2),      \" __NR_ulimit is 58 on Linux 2.6.22/i386
+and
+.BR vserver (2)      \" __NR_vserver is 273 on Linux 2.6.22/i386
+(see also
+.BR unimplemented (2)).
+However,
+.BR ftime (3),
+.BR profil (3),
+and
+.BR ulimit (3)
+exist as library routines.
+The slot for
+.BR phys (2)
+is in use since Linux 2.1.116 for
+.BR umount (2);
+.BR phys (2)
+will never be implemented.
+The
+.BR getpmsg (2)
+and
+.BR putpmsg (2)
+calls are for kernels patched to support STREAMS,
+and may never be in the standard kernel.
+.P
+There was briefly
+.BR set_zone_reclaim (2),
+added in Linux 2.6.13, and removed in Linux 2.6.16;
+this system call was never available to user space.
+.\"
+.SS System calls on removed ports
+Some system calls only ever existed on Linux architectures that have
+since been removed from the kernel:
+.TP
+AVR32 (port removed in Linux 4.12)
+.RS
+.PD 0
+.IP \[bu] 3
+.BR pread (2)
+.IP \[bu]
+.BR pwrite (2)
+.PD
+.RE
+.TP
+Blackfin (port removed in Linux 4.17)
+.RS
+.PD 0
+.IP \[bu] 3
+.BR bfin_spinlock (2)
+(added in Linux 2.6.22)
+.IP \[bu]
+.BR dma_memcpy (2)
+(added in Linux 2.6.22)
+.IP \[bu]
+.BR pread (2)
+(added in Linux 2.6.22)
+.IP \[bu]
+.BR pwrite (2)
+(added in Linux 2.6.22)
+.IP \[bu]
+.BR sram_alloc (2)
+(added in Linux 2.6.22)
+.IP \[bu]
+.BR sram_free (2)
+(added in Linux 2.6.22)
+.PD
+.RE
+.TP
+Metag (port removed in Linux 4.17)
+.RS
+.PD 0
+.IP \[bu] 3
+.BR metag_get_tls (2)
+(add in Linux 3.9)
+.IP \[bu]
+.BR metag_set_fpu_flags (2)
+(add in Linux 3.9)
+.IP \[bu]
+.BR metag_set_tls (2)
+(add in Linux 3.9)
+.IP \[bu]
+.BR metag_setglobalbit (2)
+(add in Linux 3.9)
+.PD
+.RE
+.TP
+Tile (port removed in Linux 4.17)
+.RS
+.PD 0
+.IP \[bu] 3
+.BR cmpxchg_badaddr (2)
+(added in Linux 2.6.36)
+.PD
+.RE
+.SH NOTES
+Roughly speaking, the code belonging to the system call
+with number __NR_xxx defined in
+.I /usr/include/asm/unistd.h
+can be found in the Linux kernel source in the routine
+.IR sys_xxx ().
+There are many exceptions, however, mostly because
+older system calls were superseded by newer ones,
+and this has been treated somewhat unsystematically.
+On platforms with
+proprietary operating-system emulation,
+such as sparc, sparc64, and alpha,
+there are many additional system calls; mips64 also contains a full
+set of 32-bit system calls.
+.P
+Over time, changes to the interfaces of some system calls have been
+necessary.
+One reason for such changes was the need to increase the size of
+structures or scalar values passed to the system call.
+Because of these changes, certain architectures
+(notably, longstanding 32-bit architectures such as i386)
+now have various groups of related system calls (e.g.,
+.BR truncate (2)
+and
+.BR truncate64 (2))
+which perform similar tasks, but which vary in
+details such as the size of their arguments.
+(As noted earlier, applications are generally unaware of this:
+the glibc wrapper functions do some work to ensure that the right
+system call is invoked, and that ABI compatibility is
+preserved for old binaries.)
+Examples of system calls that exist in multiple versions are
+the following:
+.IP \[bu] 3
+By now there are three different versions of
+.BR stat (2):
+.IR sys_stat ()
+(slot
+.IR __NR_oldstat ),
+.IR sys_newstat ()
+(slot
+.IR __NR_stat ),
+and
+.IR sys_stat64 ()
+(slot
+.IR __NR_stat64 ),
+with the last being the most current.
+.\" e.g., on 2.6.22/i386: __NR_oldstat 18, __NR_stat 106, __NR_stat64 195
+.\" The stat system calls deal with three different data structures,
+.\" defined in include/asm-i386/stat.h: __old_kernel_stat, stat, stat64
+A similar story applies for
+.BR lstat (2)
+and
+.BR fstat (2).
+.IP \[bu]
+Similarly, the defines
+.IR __NR_oldolduname ,
+.IR __NR_olduname ,
+and
+.I __NR_uname
+refer to the routines
+.IR sys_olduname (),
+.IR sys_uname (),
+and
+.IR sys_newuname ().
+.IP \[bu]
+In Linux 2.0, a new version of
+.BR vm86 (2)
+appeared, with the old and the new kernel routines being named
+.IR sys_vm86old ()
+and
+.IR sys_vm86 ().
+.IP \[bu]
+In Linux 2.4, a new version of
+.BR getrlimit (2)
+appeared, with the old and the new kernel routines being named
+.IR sys_old_getrlimit ()
+(slot
+.IR __NR_getrlimit )
+and
+.IR sys_getrlimit ()
+(slot
+.IR __NR_ugetrlimit ).
+.IP \[bu]
+Linux 2.4 increased the size of user and group IDs from 16 to 32 bits.
+.\" 64-bit off_t changes: ftruncate64, *stat64,
+.\" fcntl64 (because of the flock structure), getdents64, *statfs64
+To support this change, a range of system calls were added
+(e.g.,
+.BR chown32 (2),
+.BR getuid32 (2),
+.BR getgroups32 (2),
+.BR setresuid32 (2)),
+superseding earlier calls of the same name without the
+"32" suffix.
+.IP \[bu]
+Linux 2.4 added support for applications on 32-bit architectures
+to access large files (i.e., files for which the sizes and
+file offsets can't be represented in 32 bits.)
+To support this change, replacements were required for system calls
+that deal with file offsets and sizes.
+Thus the following system calls were added:
+.BR fcntl64 (2),
+.BR getdents64 (2),
+.BR stat64 (2),
+.BR statfs64 (2),
+.BR truncate64 (2),
+and their analogs that work with file descriptors or
+symbolic links.
+These system calls supersede the older system calls
+which, except in the case of the "stat" calls,
+have the same name without the "64" suffix.
+.IP
+On newer platforms that only have 64-bit file access and 32-bit UIDs/GIDs
+(e.g., alpha, ia64, s390x, x86-64), there is just a single version of
+the UID/GID and file access system calls.
+On platforms (typically, 32-bit platforms) where the *64 and *32 calls exist,
+the other versions are obsolete.
+.IP \[bu]
+The
+.I rt_sig*
+calls were added in Linux 2.2 to support the addition
+of real-time signals (see
+.BR signal (7)).
+These system calls supersede the older system calls of the same
+name without the "rt_" prefix.
+.IP \[bu]
+The
+.BR select (2)
+and
+.BR mmap (2)
+system calls use five or more arguments,
+which caused problems in the way
+argument passing on the i386 used to be set up.
+Thus, while other architectures have
+.IR sys_select ()
+and
+.IR sys_mmap ()
+corresponding to
+.I __NR_select
+and
+.IR __NR_mmap ,
+on i386 one finds
+.IR old_select ()
+and
+.IR old_mmap ()
+(routines that use a pointer to an
+argument block) instead.
+These days passing five arguments
+is not a problem any more, and there is a
+.I __NR__newselect
+.\" (used by libc 6)
+that corresponds directly to
+.IR sys_select ()
+and similarly
+.IR __NR_mmap2 .
+s390x is the only 64-bit architecture that has
+.IR old_mmap ().
+.\" .P
+.\" Two system call numbers,
+.\" .IR __NR__llseek
+.\" and
+.\" .IR __NR__sysctl
+.\" have an additional underscore absent in
+.\" .IR sys_llseek ()
+.\" and
+.\" .IR sys_sysctl ().
+.\"
+.\" In Linux 2.1.81,
+.\" .BR lchown (2)
+.\" and
+.\" .BR chown (2)
+.\" were swapped; that is,
+.\" .BR lchown (2)
+.\" was added with the semantics that were then current for
+.\" .BR chown (2),
+.\" and the semantics of the latter call were changed to what
+.\" they are today.
+.\"
+.\"
+.SS "Architecture-specific details: Alpha"
+.TP
+.BR getxgid (2)
+returns a pair of GID and effective GID via registers
+\fBr0\fP and \fBr20\fP; it is provided
+instead of
+\fBgetgid\fP(2) and \fBgetegid\fP(2).
+.TP
+.BR getxpid (2)
+returns a pair of PID and parent PID via registers
+\fBr0\fP and \fBr20\fP; it is provided instead of
+\fBgetpid\fP(2) and \fBgetppid\fP(2).
+.TP
+.BR old_adjtimex (2)
+is a variant of \fBadjtimex\fP(2) that uses \fIstruct timeval32\fP,
+for compatibility with OSF/1.
+.TP
+.BR getxuid (2)
+returns a pair of GID and effective GID via registers
+\fBr0\fP and \fBr20\fP; it is provided instead of
+\fBgetuid\fP(2) and \fBgeteuid\fP(2).
+.TP
+.BR sethae (2)
+is used for configuring the Host Address Extension register on
+low-cost Alphas in order to access address space beyond first 27 bits.
+.SH SEE ALSO
+.BR ausyscall (1),
+.BR intro (2),
+.BR syscall (2),
+.BR unimplemented (2),
+.BR errno (3),
+.BR libc (7),
+.BR vdso (7)
diff --git a/man/man2/sysctl.2 b/man/man2/sysctl.2
new file mode 100644
index 000000000..3d91dc632
--- /dev/null
+++ b/man/man2/sysctl.2
@@ -0,0 +1,160 @@
+.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Written 11 April 1996 by Andries Brouwer <aeb@cwi.nl>
+.\" 960412: Added comments from Stephen Tweedie
+.\" Modified Tue Oct 22 22:28:41 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Mon Jan  5 20:31:04 1998 by aeb.
+.\"
+.TH sysctl 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysctl \- read/write system parameters
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.B #include <linux/sysctl.h>
+.P
+.BI "[[deprecated]] int _sysctl(struct __sysctl_args *" args );
+.fi
+.SH DESCRIPTION
+.B This system call no longer exists on current kernels!
+See NOTES.
+.P
+The
+.BR _sysctl ()
+call reads and/or writes kernel parameters.
+For example, the hostname,
+or the maximum number of open files.
+The argument has the form
+.P
+.in +4n
+.EX
+struct __sysctl_args {
+    int    *name;    /* integer vector describing variable */
+    int     nlen;    /* length of this vector */
+    void   *oldval;  /* 0 or address where to store old value */
+    size_t *oldlenp; /* available room for old value,
+                        overwritten by actual size of old value */
+    void   *newval;  /* 0 or address of new value */
+    size_t  newlen;  /* size of new value */
+};
+.EE
+.in
+.P
+This call does a search in a tree structure, possibly resembling
+a directory tree under
+.IR /proc/sys ,
+and if the requested item is found calls some appropriate routine
+to read or modify the value.
+.SH RETURN VALUE
+Upon successful completion,
+.BR _sysctl ()
+returns 0.
+Otherwise, a value of \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.TQ
+.B EPERM
+No search permission for one of the encountered "directories",
+or no read permission where
+.I oldval
+was nonzero, or no write permission where
+.I newval
+was nonzero.
+.TP
+.B EFAULT
+The invocation asked for the previous value by setting
+.I oldval
+non-NULL, but allowed zero room in
+.IR oldlenp .
+.TP
+.B ENOTDIR
+.I name
+was not found.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 1.3.57.
+Removed in Linux 5.5, glibc 2.32.
+.P
+It originated in
+4.4BSD.
+Only Linux has the
+.I /proc/sys
+mirror, and the object naming schemes differ between Linux and 4.4BSD,
+but the declaration of the
+.BR sysctl ()
+function is the same in both.
+.SH NOTES
+Use of this system call was long discouraged:
+since Linux 2.6.24,
+uses of this system call result in warnings in the kernel log,
+and in Linux 5.5, the system call was finally removed.
+Use the
+.I /proc/sys
+interface instead.
+.P
+Note that on older kernels where this system call still exists,
+it is available only if the kernel was configured with the
+.B CONFIG_SYSCTL_SYSCALL
+option.
+Furthermore, glibc does not provide a wrapper for this system call,
+necessitating the use of
+.BR syscall (2).
+.SH BUGS
+The object names vary between kernel versions,
+making this system call worthless for applications.
+.P
+Not all available objects are properly documented.
+.P
+It is not yet possible to change operating system by writing to
+.IR /proc/sys/kernel/ostype .
+.SH EXAMPLES
+.\" SRC BEGIN (sysctl.c)
+.EX
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+#include <linux/sysctl.h>
+\&
+#define ARRAY_SIZE(arr)  (sizeof(arr) / sizeof((arr)[0]))
+\&
+int _sysctl(struct __sysctl_args *args);
+\&
+#define OSNAMESZ 100
+\&
+int
+main(void)
+{
+    int                   name[] = { CTL_KERN, KERN_OSTYPE };
+    char                  osname[OSNAMESZ];
+    size_t                osnamelth;
+    struct __sysctl_args  args;
+\&
+    memset(&args, 0, sizeof(args));
+    args.name = name;
+    args.nlen = ARRAY_SIZE(name);
+    args.oldval = osname;
+    args.oldlenp = &osnamelth;
+\&
+    osnamelth = sizeof(osname);
+\&
+    if (syscall(SYS__sysctl, &args) == \-1) {
+        perror("_sysctl");
+        exit(EXIT_FAILURE);
+    }
+    printf("This machine is running %*s\en", (int) osnamelth, osname);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man2/sysfs.2 b/man/man2/sysfs.2
new file mode 100644
index 000000000..6e75cf3ae
--- /dev/null
+++ b/man/man2/sysfs.2
@@ -0,0 +1,97 @@
+.\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created   Wed Aug  9 1995     Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\"
+.TH sysfs 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysfs \- get filesystem type information
+.SH SYNOPSIS
+.nf
+.BI "[[deprecated]] int sysfs(int " option ", const char *" fsname );
+.BI "[[deprecated]] int sysfs(int " option ", unsigned int " fs_index ", char *" buf );
+.BI "[[deprecated]] int sysfs(int " option );
+.fi
+.SH DESCRIPTION
+.BR "Note" :
+if you are looking for information about the
+.B sysfs
+filesystem that is normally mounted at
+.IR /sys ,
+see
+.BR sysfs (5).
+.P
+The (obsolete)
+.BR sysfs ()
+system call returns information about the filesystem types
+currently present in the kernel.
+The specific form of the
+.BR sysfs ()
+call and the information returned depends on the
+.I option
+in effect:
+.TP 3
+.B 1
+Translate the filesystem identifier string
+.I fsname
+into a filesystem type index.
+.TP
+.B 2
+Translate the filesystem type index
+.I fs_index
+into a null-terminated filesystem identifier string.
+This string will
+be written to the buffer pointed to by
+.IR buf .
+Make sure that
+.I buf
+has enough space to accept the string.
+.TP
+.B 3
+Return the total number of filesystem types currently present in the
+kernel.
+.P
+The numbering of the filesystem type indexes begins with zero.
+.SH RETURN VALUE
+On success,
+.BR sysfs ()
+returns the filesystem index for option
+.BR 1 ,
+zero for option
+.BR 2 ,
+and the number of currently configured filesystems for option
+.BR 3 .
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.RI "Either " fsname " or " buf
+is outside your accessible address space.
+.TP
+.B EINVAL
+.I fsname
+is not a valid filesystem type identifier;
+.I fs_index
+is out-of-bounds;
+.I option
+is invalid.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4.
+.P
+This System-V derived system call is obsolete; don't use it.
+On systems with
+.IR /proc ,
+the same information can be obtained via
+.IR /proc ;
+use that interface instead.
+.SH BUGS
+There is no libc or glibc support.
+There is no way to guess how large \fIbuf\fP should be.
+.SH SEE ALSO
+.BR proc (5),
+.BR sysfs (5)
diff --git a/man/man2/sysinfo.2 b/man/man2/sysinfo.2
new file mode 100644
index 000000000..75c578404
--- /dev/null
+++ b/man/man2/sysinfo.2
@@ -0,0 +1,106 @@
+.\" Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Based on an earlier version of the page where a few pieces were
+.\" copyright (C) 1993 by Dan Miner (dminer@nyx.cs.du.edu) and subsequently
+.\" others (see old changelog below).
+.\" The structure definitions are taken more or less straight from the kernel
+.\" source files.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.\" Modified Sat Jul 24 12:35:12 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 22:29:51 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Mon Aug 25 16:06:11 1997 by Nicolás Lichtmaier <nick@debian.org>
+.\"
+.TH sysinfo 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysinfo \- return system information
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/sysinfo.h>
+.P
+.BI "int sysinfo(struct sysinfo *" info );
+.fi
+.SH DESCRIPTION
+.BR sysinfo ()
+returns certain statistics on memory and swap usage,
+as well as the load average.
+.P
+Until Linux 2.3.16,
+.BR sysinfo ()
+returned information in the following structure:
+.P
+.in +4n
+.EX
+struct sysinfo {
+    long uptime;             /* Seconds since boot */
+    unsigned long loads[3];  /* 1, 5, and 15 minute load averages */
+    unsigned long totalram;  /* Total usable main memory size */
+    unsigned long freeram;   /* Available memory size */
+    unsigned long sharedram; /* Amount of shared memory */
+    unsigned long bufferram; /* Memory used by buffers */
+    unsigned long totalswap; /* Total swap space size */
+    unsigned long freeswap;  /* Swap space still available */
+    unsigned short procs;    /* Number of current processes */
+    char _f[22];             /* Pads structure to 64 bytes */
+};
+.EE
+.in
+.P
+In the above structure, the sizes of the memory and swap fields
+are given in bytes.
+.P
+Since Linux 2.3.23 (i386) and Linux 2.3.48
+(all architectures) the structure is:
+.P
+.in +4n
+.EX
+struct sysinfo {
+    long uptime;             /* Seconds since boot */
+    unsigned long loads[3];  /* 1, 5, and 15 minute load averages */
+    unsigned long totalram;  /* Total usable main memory size */
+    unsigned long freeram;   /* Available memory size */
+    unsigned long sharedram; /* Amount of shared memory */
+    unsigned long bufferram; /* Memory used by buffers */
+    unsigned long totalswap; /* Total swap space size */
+    unsigned long freeswap;  /* Swap space still available */
+    unsigned short procs;    /* Number of current processes */
+    unsigned long totalhigh; /* Total high memory size */
+    unsigned long freehigh;  /* Available high memory size */
+    unsigned int mem_unit;   /* Memory unit size in bytes */
+    char _f[20\-2*sizeof(long)\-sizeof(int)];
+                             /* Padding to 64 bytes */
+};
+.EE
+.in
+.P
+In the above structure,
+sizes of the memory and swap fields are given as multiples of
+.I mem_unit
+bytes.
+.SH RETURN VALUE
+On success,
+.BR sysinfo ()
+returns zero.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I info
+is not a valid address.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 0.98.pl6.
+.SH NOTES
+All of the information provided by this system call is also available via
+.I /proc/meminfo
+and
+.IR /proc/loadavg .
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man2/syslog.2 b/man/man2/syslog.2
new file mode 100644
index 000000000..15426badf
--- /dev/null
+++ b/man/man2/syslog.2
@@ -0,0 +1,378 @@
+'\" t
+.\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (C) 2012, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Written 11 June 1995 by Andries Brouwer <aeb@cwi.nl>
+.\" 2008-02-15, Jeremy Kerr <jk@ozlabs.org>
+.\"     Add info on command type 10; add details on types 6, 7, 8, & 9.
+.\" 2008-02-15, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Update LOG_BUF_LEN details; update RETURN VALUE section.
+.\"
+.TH syslog 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+syslog, klogctl \- read and/or clear kernel message ring buffer;
+set console_loglevel
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/klog.h>" "        /* Definition of " SYSLOG_* " constants */"
+.BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_syslog, int " type ", char *" bufp ", int " len );
+.P
+/* The glibc interface */
+.B #include <sys/klog.h>
+.P
+.BI "int klogctl(int " type ", char *" bufp ", int " len );
+.fi
+.SH DESCRIPTION
+.IR Note :
+Probably, you are looking for the C library function
+.BR syslog (),
+which talks to
+.BR syslogd (8);
+see
+.BR syslog (3)
+for details.
+.P
+This page describes the kernel
+.BR syslog ()
+system call, which is used to control the kernel
+.IR printk ()
+buffer; the glibc wrapper function for the system call is called
+.BR klogctl ().
+.SS The kernel log buffer
+The kernel has a cyclic buffer of length
+.B LOG_BUF_LEN
+in which messages given as arguments to the kernel function
+.BR printk ()
+are stored (regardless of their log level).
+In early kernels,
+.B LOG_BUF_LEN
+had the value 4096;
+from Linux 1.3.54, it was 8192;
+from Linux 2.1.113, it was 16384;
+since Linux 2.4.23/2.6, the value is a kernel configuration option
+.RB ( CONFIG_LOG_BUF_SHIFT ,
+default value dependent on the architecture).
+.\" Under "General setup" ==> "Kernel log buffer size"
+.\" For Linux 2.6, precisely the option seems to have appeared in Linux 2.5.55.
+Since Linux 2.6.6, the size can be queried with command type 10 (see below).
+.SS Commands
+The \fItype\fP argument determines the action taken by this function.
+The list below specifies the values for
+.IR type .
+The symbolic names are defined in the kernel source,
+but are not exported to user space;
+you will either need to use the numbers, or define the names yourself.
+.TP
+.BR SYSLOG_ACTION_CLOSE " (0)"
+Close the log.
+Currently a NOP.
+.TP
+.BR SYSLOG_ACTION_OPEN " (1)"
+Open the log.
+Currently a NOP.
+.TP
+.BR SYSLOG_ACTION_READ " (2)"
+Read from the log.
+The call
+waits until the kernel log buffer is nonempty, and then reads
+at most \fIlen\fP bytes into the buffer pointed to by
+.IR bufp .
+The call returns the number of bytes read.
+Bytes read from the log disappear from the log buffer:
+the information can be read only once.
+This is the function executed by the kernel when a user program reads
+.IR /proc/kmsg .
+.TP
+.BR SYSLOG_ACTION_READ_ALL " (3)"
+Read all messages remaining in the ring buffer,
+placing them in the buffer pointed to by
+.IR bufp .
+The call reads the last \fIlen\fP
+bytes from the log buffer (nondestructively),
+but will not read more than was written into the buffer since the
+last "clear ring buffer" command (see command 5 below)).
+The call returns the number of bytes read.
+.TP
+.BR SYSLOG_ACTION_READ_CLEAR " (4)"
+Read and clear all messages remaining in the ring buffer.
+The call does precisely the same as for a
+.I type
+of 3, but also executes the "clear ring buffer" command.
+.TP
+.BR SYSLOG_ACTION_CLEAR " (5)"
+The call executes just the "clear ring buffer" command.
+The
+.I bufp
+and
+.I len
+arguments are ignored.
+.IP
+This command does not really clear the ring buffer.
+Rather, it sets a kernel bookkeeping variable that
+determines the results returned by commands 3
+.RB ( SYSLOG_ACTION_READ_ALL )
+and 4
+.RB ( SYSLOG_ACTION_READ_CLEAR ).
+This command has no effect on commands 2
+.RB ( SYSLOG_ACTION_READ )
+and 9
+.RB ( SYSLOG_ACTION_SIZE_UNREAD ).
+.TP
+.BR SYSLOG_ACTION_CONSOLE_OFF " (6)"
+The command saves the current value of
+.I console_loglevel
+and then sets
+.I console_loglevel
+to
+.IR minimum_console_loglevel ,
+so that no messages are printed to the console.
+Before Linux 2.6.32,
+.\" commit 1aaad49e856ce41adc07d8ae0c8ef35fc4483245
+the command simply sets
+.I console_loglevel
+to
+.IR minimum_console_loglevel .
+See the discussion of
+.IR /proc/sys/kernel/printk ,
+below.
+.IP
+The
+.I bufp
+and
+.I len
+arguments are ignored.
+.TP
+.BR SYSLOG_ACTION_CONSOLE_ON " (7)"
+If a previous
+.B SYSLOG_ACTION_CONSOLE_OFF
+command has been performed,
+this command restores
+.I console_loglevel
+to the value that was saved by that command.
+Before Linux 2.6.32,
+.\" commit 1aaad49e856ce41adc07d8ae0c8ef35fc4483245
+this command simply sets
+.I console_loglevel
+to
+.IR default_console_loglevel .
+See the discussion of
+.IR /proc/sys/kernel/printk ,
+below.
+.IP
+The
+.I bufp
+and
+.I len
+arguments are ignored.
+.TP
+.BR SYSLOG_ACTION_CONSOLE_LEVEL " (8)"
+The call sets
+.I console_loglevel
+to the value given in
+.IR len ,
+which must be an integer between 1 and 8 (inclusive).
+The kernel silently enforces a minimum value of
+.I minimum_console_loglevel
+for
+.IR len .
+See the
+.I log level
+section for details.
+The
+.I bufp
+argument is ignored.
+.TP
+.BR SYSLOG_ACTION_SIZE_UNREAD " (9) (since Linux 2.4.10)"
+The call
+returns the number of bytes currently available to be read
+from the kernel log buffer via command 2
+.RB ( SYSLOG_ACTION_READ ).
+The
+.I bufp
+and
+.I len
+arguments are ignored.
+.TP
+.BR SYSLOG_ACTION_SIZE_BUFFER " (10) (since Linux 2.6.6)"
+This command returns the total size of the kernel log buffer.
+The
+.I bufp
+and
+.I len
+arguments are ignored.
+.P
+All commands except 3 and 10 require privilege.
+In Linux kernels before Linux 2.6.37,
+command types 3 and 10 are allowed to unprivileged processes;
+since Linux 2.6.37,
+these commands are allowed to unprivileged processes only if
+.I /proc/sys/kernel/dmesg_restrict
+has the value 0.
+Before Linux 2.6.37, "privileged" means that the caller has the
+.B CAP_SYS_ADMIN
+capability.
+Since Linux 2.6.37,
+"privileged" means that the caller has either the
+.B CAP_SYS_ADMIN
+capability (now deprecated for this purpose) or the (new)
+.B CAP_SYSLOG
+capability.
+.\"
+.\"
+.SS /proc/sys/kernel/printk
+.I /proc/sys/kernel/printk
+is a writable file containing four integer values that influence kernel
+.I printk()
+behavior when printing or logging error messages.
+The four values are:
+.TP
+.I console_loglevel
+Only messages with a log level lower than this value will
+be printed to the console.
+The default value for this field is
+.B DEFAULT_CONSOLE_LOGLEVEL
+(7), but it is set to
+4 if the kernel command line contains the word "quiet",\" since Linux 2.4
+10 if the kernel command line contains the word "debug",
+and to 15 in case
+of a kernel fault (the 10 and 15 are just silly, and equivalent to 8).
+The value of
+.I console_loglevel
+can be set (to a value in the range 1\[en]8) by a
+.BR syslog ()
+call with a
+.I type
+of 8.
+.TP
+.I default_message_loglevel
+This value will be used as the log level for
+.I printk()
+messages that do not have an explicit level.
+Up to and including Linux 2.6.38,
+the hard-coded default value for this field was 4
+.RB ( KERN_WARNING );
+since Linux 2.6.39,
+.\" commit 5af5bcb8d37f99ba415a1adc6da71051b84f93a5
+the default value is defined by the kernel configuration option
+.BR CONFIG_DEFAULT_MESSAGE_LOGLEVEL ,
+which defaults to 4.
+.TP
+.I minimum_console_loglevel
+The value in this field is the minimum value to which
+.I console_loglevel
+can be set.
+.TP
+.I default_console_loglevel
+This is the default value for
+.IR console_loglevel .
+.\"
+.\"
+.SS The log level
+Every
+.IR printk ()
+message has its own log level.
+If the log level is not explicitly specified as part of the message,
+it defaults to
+.IR default_message_loglevel .
+The conventional meaning of the log level is as follows:
+.TS
+lB lB lB
+lB c l.
+Kernel constant	Level value	Meaning
+KERN_EMERG	0	System is unusable
+KERN_ALERT	1	T{
+Action must be taken immediately
+T}
+KERN_CRIT	2	Critical conditions
+KERN_ERR	3	Error conditions
+KERN_WARNING	4	Warning conditions
+KERN_NOTICE	5	T{
+Normal but significant condition
+T}
+KERN_INFO	6	Informational
+KERN_DEBUG	7	Debug-level messages
+.TE
+.P
+The kernel
+.I printk()
+routine will print a message on the
+console only if it has a log level less than the value of
+.IR console_loglevel .
+.SH RETURN VALUE
+For \fItype\fP equal to 2, 3, or 4, a successful call to
+.BR syslog ()
+returns the number
+of bytes read.
+For \fItype\fP 9,
+.BR syslog ()
+returns the number of bytes currently
+available to be read on the kernel log buffer.
+For \fItype\fP 10,
+.BR syslog ()
+returns the total size of the kernel log buffer.
+For other values of \fItype\fP, 0 is returned on success.
+.P
+In case of error, \-1 is returned,
+and \fIerrno\fP is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+Bad arguments (e.g.,
+bad
+.IR type ;
+or for
+.I type
+2, 3, or 4,
+.I buf
+is NULL,
+or
+.I len
+is less than zero; or for
+.I type
+8, the
+.I level
+is outside the range 1 to 8).
+.TP
+.B ENOSYS
+This
+.BR syslog ()
+system call is not available, because the kernel was compiled with the
+.B CONFIG_PRINTK
+kernel-configuration option disabled.
+.TP
+.B EPERM
+An attempt was made to change
+.I console_loglevel
+or clear the kernel
+message ring buffer by a process without sufficient privilege
+(more precisely: without the
+.B CAP_SYS_ADMIN
+or
+.B CAP_SYSLOG
+capability).
+.TP
+.B ERESTARTSYS
+System call was interrupted by a signal; nothing was read.
+(This can be seen only during a trace.)
+.SH STANDARDS
+Linux.
+.SH HISTORY
+From the very start, people noted that it is unfortunate that
+a system call and a library routine of the same name are entirely
+different animals.
+.\" In libc4 and libc5 the number of this call was defined by
+.\" .BR SYS_klog .
+.\" In glibc 2.0 the syscall is baptized
+.\" .BR klogctl ().
+.SH SEE ALSO
+.BR dmesg (1),
+.BR syslog (3),
+.BR capabilities (7)
diff --git a/man/man2/tee.2 b/man/man2/tee.2
new file mode 100644
index 000000000..8ed9a67a8
--- /dev/null
+++ b/man/man2/tee.2
@@ -0,0 +1,199 @@
+.\" This manpage is Copyright (C) 2006 Jens Axboe
+.\" and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH tee 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tee \- duplicating pipe content
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <fcntl.h>
+.P
+.BI "ssize_t tee(int " fd_in ", int " fd_out ", size_t " len \
+", unsigned int " flags );
+.fi
+.\" Return type was long before glibc 2.7
+.SH DESCRIPTION
+.\" Example programs http://brick.kernel.dk/snaps
+.\"
+.\"
+.\" add a "tee(in, out1, out2)" system call that duplicates the pages
+.\" (again, incrementing their reference count, not copying the data) from
+.\" one pipe to two other pipes.
+.BR tee ()
+duplicates up to
+.I len
+bytes of data from the pipe referred to by the file descriptor
+.I fd_in
+to the pipe referred to by the file descriptor
+.IR fd_out .
+It does not consume the data that is duplicated from
+.IR fd_in ;
+therefore, that data can be copied by a subsequent
+.BR splice (2).
+.P
+.I flags
+is a bit mask that is composed by ORing together
+zero or more of the following values:
+.TP 1.9i
+.B SPLICE_F_MOVE
+Currently has no effect for
+.BR tee ();
+see
+.BR splice (2).
+.TP
+.B SPLICE_F_NONBLOCK
+Do not block on I/O; see
+.BR splice (2)
+for further details.
+.TP
+.B SPLICE_F_MORE
+Currently has no effect for
+.BR tee (),
+but may be implemented in the future; see
+.BR splice (2).
+.TP
+.B SPLICE_F_GIFT
+Unused for
+.BR tee ();
+see
+.BR vmsplice (2).
+.SH RETURN VALUE
+Upon successful completion,
+.BR tee ()
+returns the number of bytes that were duplicated between the input
+and output.
+A return value of 0 means that there was no data to transfer,
+and it would not make sense to block, because there are no
+writers connected to the write end of the pipe referred to by
+.IR fd_in .
+.P
+On error,
+.BR tee ()
+returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+.B SPLICE_F_NONBLOCK
+was specified in
+.I flags
+or one of the file descriptors had been marked as nonblocking
+.RB ( O_NONBLOCK ) ,
+and the operation would block.
+.TP
+.B EINVAL
+.I fd_in
+or
+.I fd_out
+does not refer to a pipe; or
+.I fd_in
+and
+.I fd_out
+refer to the same pipe.
+.TP
+.B ENOMEM
+Out of memory.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.17,
+glibc 2.5.
+.SH NOTES
+Conceptually,
+.BR tee ()
+copies the data between the two pipes.
+In reality no real data copying takes place though:
+under the covers,
+.BR tee ()
+assigns data to the output by merely grabbing
+a reference to the input.
+.SH EXAMPLES
+The example below implements a basic
+.BR tee (1)
+program using the
+.BR tee ()
+system call.
+Here is an example of its use:
+.P
+.in +4n
+.EX
+$ \fBdate | ./a.out out.log | cat\fP
+Tue Oct 28 10:06:00 CET 2014
+$ \fBcat out.log\fP
+Tue Oct 28 10:06:00 CET 2014
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (tee.c)
+.EX
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int      fd;
+    ssize_t  len, slen;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0644);
+    if (fd == \-1) {
+        perror("open");
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (;;) {
+        /*
+         * tee stdin to stdout.
+         */
+        len = tee(STDIN_FILENO, STDOUT_FILENO,
+                  INT_MAX, SPLICE_F_NONBLOCK);
+        if (len < 0) {
+            if (errno == EAGAIN)
+                continue;
+            perror("tee");
+            exit(EXIT_FAILURE);
+        }
+        if (len == 0)
+            break;
+\&
+        /*
+         * Consume stdin by splicing it to a file.
+         */
+        while (len > 0) {
+            slen = splice(STDIN_FILENO, NULL, fd, NULL,
+                          len, SPLICE_F_MOVE);
+            if (slen < 0) {
+                perror("splice");
+                exit(EXIT_FAILURE);
+            }
+            len \-= slen;
+        }
+    }
+\&
+    close(fd);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR splice (2),
+.BR vmsplice (2),
+.BR pipe (7)
diff --git a/man/man2/tgkill.2 b/man/man2/tgkill.2
new file mode 100644
index 000000000..82fc2d6af
--- /dev/null
+++ b/man/man2/tgkill.2
@@ -0,0 +1 @@
+.so man2/tkill.2
diff --git a/man/man2/time.2 b/man/man2/time.2
new file mode 100644
index 000000000..e85029db0
--- /dev/null
+++ b/man/man2/time.2
@@ -0,0 +1,114 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified Sat Jul 24 14:13:40 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Additions by Joseph S. Myers <jsm28@cam.ac.uk>, 970909
+.\"
+.TH time 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+time \- get time in seconds
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "time_t time(time_t *_Nullable " tloc );
+.fi
+.SH DESCRIPTION
+.BR time ()
+returns the time as the number of seconds since the
+Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.P
+If
+.I tloc
+is non-NULL,
+the return value is also stored in the memory pointed to by
+.IR tloc .
+.SH RETURN VALUE
+On success, the value of time in seconds since the Epoch is returned.
+On error, \fI((time_t)\ \-1)\fP is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EOVERFLOW
+The time cannot be represented as a
+.I time_t
+value.
+This can happen if an executable with 32-bit
+.I time_t
+is run on a 64-bit kernel when the time is 2038-01-19 03:14:08 UTC or later.
+However, when the system time is out of
+.I time_t
+range in other situations, the behavior is undefined.
+.TP
+.B EFAULT
+.I tloc
+points outside your accessible address space (but see BUGS).
+.IP
+On systems where the C library
+.BR time ()
+wrapper function invokes an implementation provided by the
+.BR vdso (7)
+(so that there is no trap into the kernel),
+an invalid address may instead trigger a
+.B SIGSEGV
+signal.
+.SH VERSIONS
+POSIX.1 defines
+.I seconds since the Epoch
+using a formula that approximates the number of seconds between a
+specified time and the Epoch.
+This formula takes account of the facts that
+all years that are evenly divisible by 4 are leap years,
+but years that are evenly divisible by 100 are not leap years
+unless they are also evenly divisible by 400,
+in which case they are leap years.
+This value is not the same as the actual number of seconds between the time
+and the Epoch, because of leap seconds and because system clocks are not
+required to be synchronized to a standard reference.
+Linux systems normally follow the POSIX requirement
+that this value ignore leap seconds,
+so that conforming systems interpret it consistently;
+see POSIX.1-2018 Rationale A.4.16.
+.P
+Applications intended to run after 2038 should use ABIs with
+.I time_t
+wider than 32 bits; see
+.BR time_t (3type).
+.SS C library/kernel differences
+On some architectures, an implementation of
+.BR time ()
+is provided in the
+.BR vdso (7).
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+SVr4, 4.3BSD, C89, POSIX.1-2001.
+.\" Under 4.3BSD, this call is obsoleted by
+.\" .BR gettimeofday (2).
+.SH BUGS
+Error returns from this system call are indistinguishable from
+successful reports that the time is a few seconds
+.I before
+the Epoch, so the C library wrapper function never sets
+.I errno
+as a result of this call.
+.P
+The
+.I tloc
+argument is obsolescent and should always be NULL in new code.
+When
+.I tloc
+is NULL, the call cannot fail.
+.SH SEE ALSO
+.BR date (1),
+.BR gettimeofday (2),
+.BR ctime (3),
+.BR ftime (3),
+.BR time (7),
+.BR vdso (7)
diff --git a/man/man2/timer_create.2 b/man/man2/timer_create.2
new file mode 100644
index 000000000..1109858b8
--- /dev/null
+++ b/man/man2/timer_create.2
@@ -0,0 +1,487 @@
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH timer_create 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+timer_create \- create a POSIX per-process timer
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.BR "#include <signal.h>" "           /* Definition of " SIGEV_* " constants */"
+.B  #include <time.h>
+.P
+.BI "int timer_create(clockid_t " clockid ,
+.BI "                 struct sigevent *_Nullable restrict " sevp ,
+.BI "                 timer_t *restrict " timerid );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR timer_create ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+.BR timer_create ()
+creates a new per-process interval timer.
+The ID of the new timer is returned in the buffer pointed to by
+.IR timerid ,
+which must be a non-null pointer.
+This ID is unique within the process, until the timer is deleted.
+The new timer is initially disarmed.
+.P
+The
+.I clockid
+argument specifies the clock that the new timer uses to measure time.
+It can be specified as one of the following values:
+.TP
+.B CLOCK_REALTIME
+A settable system-wide real-time clock.
+.TP
+.B CLOCK_MONOTONIC
+A nonsettable monotonically increasing clock that measures time
+from some unspecified point in the past that does not change
+after system startup.
+.\" Note: the CLOCK_MONOTONIC_RAW clock added for clock_gettime()
+.\" in Linux 2.6.28 is not supported for POSIX timers -- mtk, Feb 2009
+.TP
+.BR CLOCK_PROCESS_CPUTIME_ID " (since Linux 2.6.12)"
+A clock that measures (user and system) CPU time consumed by
+(all of the threads in) the calling process.
+.TP
+.BR CLOCK_THREAD_CPUTIME_ID " (since Linux 2.6.12)"
+A clock that measures (user and system) CPU time consumed by
+the calling thread.
+.\" The CLOCK_MONOTONIC_RAW that was added in Linux 2.6.28 can't be used
+.\" to create a timer -- mtk, Feb 2009
+.TP
+.BR CLOCK_BOOTTIME " (Since Linux 2.6.39)"
+.\" commit 70a08cca1227dc31c784ec930099a4417a06e7d0
+Like
+.BR CLOCK_MONOTONIC ,
+this is a monotonically increasing clock.
+However, whereas the
+.B CLOCK_MONOTONIC
+clock does not measure the time while a system is suspended, the
+.B CLOCK_BOOTTIME
+clock does include the time during which the system is suspended.
+This is useful for applications that need to be suspend-aware.
+.B CLOCK_REALTIME
+is not suitable for such applications, since that clock is affected
+by discontinuous changes to the system clock.
+.TP
+.BR CLOCK_REALTIME_ALARM " (since Linux 3.0)"
+.\" commit 9a7adcf5c6dea63d2e47e6f6d2f7a6c9f48b9337
+This clock is like
+.BR CLOCK_REALTIME ,
+but will wake the system if it is suspended.
+The caller must have the
+.B CAP_WAKE_ALARM
+capability in order to set a timer against this clock.
+.TP
+.BR CLOCK_BOOTTIME_ALARM " (since Linux 3.0)"
+.\" commit 9a7adcf5c6dea63d2e47e6f6d2f7a6c9f48b9337
+This clock is like
+.BR CLOCK_BOOTTIME ,
+but will wake the system if it is suspended.
+The caller must have the
+.B CAP_WAKE_ALARM
+capability in order to set a timer against this clock.
+.TP
+.BR CLOCK_TAI " (since Linux 3.10)"
+A system-wide clock derived from wall-clock time but counting leap seconds.
+.P
+See
+.BR clock_getres (2)
+for some further details on the above clocks.
+.P
+As well as the above values,
+.I clockid
+can be specified as the
+.I clockid
+returned by a call to
+.BR clock_getcpuclockid (3)
+or
+.BR pthread_getcpuclockid (3).
+.P
+The
+.I sevp
+argument points to a
+.I sigevent
+structure that specifies how the caller
+should be notified when the timer expires.
+For the definition and general details of this structure, see
+.BR sigevent (3type).
+.P
+The
+.I sevp.sigev_notify
+field can have the following values:
+.TP
+.B SIGEV_NONE
+Don't asynchronously notify when the timer expires.
+Progress of the timer can be monitored using
+.BR timer_gettime (2).
+.TP
+.B SIGEV_SIGNAL
+Upon timer expiration, generate the signal
+.I sigev_signo
+for the process.
+See
+.BR sigevent (3type)
+for general details.
+The
+.I si_code
+field of the
+.I siginfo_t
+structure will be set to
+.BR SI_TIMER .
+At any point in time,
+at most one signal is queued to the process for a given timer; see
+.BR timer_getoverrun (2)
+for more details.
+.TP
+.B SIGEV_THREAD
+Upon timer expiration, invoke
+.I sigev_notify_function
+as if it were the start function of a new thread.
+See
+.BR sigevent (3type)
+for details.
+.TP
+.BR SIGEV_THREAD_ID " (Linux-specific)"
+As for
+.BR SIGEV_SIGNAL ,
+but the signal is targeted at the thread whose ID is given in
+.IR sigev_notify_thread_id ,
+which must be a thread in the same process as the caller.
+The
+.I sigev_notify_thread_id
+field specifies a kernel thread ID, that is, the value returned by
+.BR clone (2)
+or
+.BR gettid (2).
+This flag is intended only for use by threading libraries.
+.P
+Specifying
+.I sevp
+as NULL is equivalent to specifying a pointer to a
+.I sigevent
+structure in which
+.I sigev_notify
+is
+.BR SIGEV_SIGNAL ,
+.I sigev_signo
+is
+.BR SIGALRM ,
+and
+.I sigev_value.sival_int
+is the timer ID.
+.SH RETURN VALUE
+On success,
+.BR timer_create ()
+returns 0, and the ID of the new timer is placed in
+.IR *timerid .
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+Temporary error during kernel allocation of timer structures.
+.TP
+.B EINVAL
+Clock ID,
+.IR sigev_notify ,
+.IR sigev_signo ,
+or
+.I sigev_notify_thread_id
+is invalid.
+.TP
+.B ENOMEM
+.\" glibc layer: malloc()
+Could not allocate memory.
+.TP
+.B ENOTSUP
+The kernel does not support creating a timer against this
+.IR clockid .
+.TP
+.B EPERM
+.I clockid
+was
+.B CLOCK_REALTIME_ALARM
+or
+.B CLOCK_BOOTTIME_ALARM
+but the caller did not have the
+.B CAP_WAKE_ALARM
+capability.
+.SH VERSIONS
+.SS C library/kernel differences
+Part of the implementation of the POSIX timers API is provided by glibc.
+.\" See nptl/sysdeps/unix/sysv/linux/timer_create.c
+In particular:
+.IP \[bu] 3
+Much of the functionality for
+.B SIGEV_THREAD
+is implemented within glibc, rather than the kernel.
+(This is necessarily so,
+since the thread involved in handling the notification is one
+that must be managed by the C library POSIX threads implementation.)
+Although the notification delivered to the process is via a thread,
+internally the NPTL implementation uses a
+.I sigev_notify
+value of
+.B SIGEV_THREAD_ID
+along with a real-time signal that is reserved by the implementation (see
+.BR nptl (7)).
+.IP \[bu]
+The implementation of the default case where
+.I evp
+is NULL is handled inside glibc,
+which invokes the underlying system call with a suitably populated
+.I sigevent
+structure.
+.IP \[bu]
+The timer IDs presented at user level are maintained by glibc,
+which maps these IDs to the timer IDs employed by the kernel.
+.\" See the glibc source file kernel-posix-timers.h for the structure
+.\" that glibc uses to map user-space timer IDs to kernel timer IDs
+.\" The kernel-level timer ID is exposed via siginfo.si_tid.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+Linux 2.6.
+POSIX.1-2001.
+.P
+Prior to Linux 2.6,
+glibc provided an incomplete user-space implementation
+.RB ( CLOCK_REALTIME
+timers only) using POSIX threads,
+and before glibc 2.17,
+.\" glibc commit 93a78ac437ba44f493333d7e2a4b0249839ce460
+the implementation falls back to this technique on systems
+running kernels older than Linux 2.6.
+.SH NOTES
+A program may create multiple interval timers using
+.BR timer_create ().
+.P
+Timers are not inherited by the child of a
+.BR fork (2),
+and are disarmed and deleted during an
+.BR execve (2).
+.P
+The kernel preallocates a "queued real-time signal"
+for each timer created using
+.BR timer_create ().
+Consequently, the number of timers is limited by the
+.B RLIMIT_SIGPENDING
+resource limit (see
+.BR setrlimit (2)).
+.P
+The timers created by
+.BR timer_create ()
+are commonly known as "POSIX (interval) timers".
+The POSIX timers API consists of the following interfaces:
+.TP
+.BR timer_create ()
+Create a timer.
+.TP
+.BR timer_settime (2)
+Arm (start) or disarm (stop) a timer.
+.TP
+.BR timer_gettime (2)
+Fetch the time remaining until the next expiration of a timer,
+along with the interval setting of the timer.
+.TP
+.BR timer_getoverrun (2)
+Return the overrun count for the last timer expiration.
+.TP
+.BR timer_delete (2)
+Disarm and delete a timer.
+.P
+Since Linux 3.10, the
+.IR /proc/ pid /timers
+file can be used to list the POSIX timers for the process with PID
+.IR pid .
+See
+.BR proc (5)
+for further information.
+.P
+Since Linux 4.10,
+.\" baa73d9e478ff32d62f3f9422822b59dd9a95a21
+support for POSIX timers is a configurable option that is enabled by default.
+Kernel support can be disabled via the
+.B CONFIG_POSIX_TIMERS
+option.
+.SH EXAMPLES
+The program below takes two arguments: a sleep period in seconds,
+and a timer frequency in nanoseconds.
+The program establishes a handler for the signal it uses for the timer,
+blocks that signal,
+creates and arms a timer that expires with the given frequency,
+sleeps for the specified number of seconds,
+and then unblocks the timer signal.
+Assuming that the timer expired at least once while the program slept,
+the signal handler will be invoked,
+and the handler displays some information about the timer notification.
+The program terminates after one invocation of the signal handler.
+.P
+In the following example run, the program sleeps for 1 second,
+after creating a timer that has a frequency of 100 nanoseconds.
+By the time the signal is unblocked and delivered,
+there have been around ten million overruns.
+.P
+.in +4n
+.EX
+$ \fB./a.out 1 100\fP
+Establishing handler for signal 34
+Blocking signal 34
+timer ID is 0x804c008
+Sleeping for 1 seconds
+Unblocking signal 34
+Caught signal 34
+    sival_ptr = 0xbfb174f4;     *sival_ptr = 0x804c008
+    overrun count = 10004886
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (timer_create.c)
+.EX
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+\&
+#define CLOCKID CLOCK_REALTIME
+#define SIG SIGRTMIN
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+static void
+print_siginfo(siginfo_t *si)
+{
+    int      or;
+    timer_t  *tidp;
+\&
+    tidp = si\->si_value.sival_ptr;
+\&
+    printf("    sival_ptr = %p; ", si\->si_value.sival_ptr);
+    printf("    *sival_ptr = %#jx\en", (uintmax_t) *tidp);
+\&
+    or = timer_getoverrun(*tidp);
+    if (or == \-1)
+        errExit("timer_getoverrun");
+    else
+        printf("    overrun count = %d\en", or);
+}
+\&
+static void
+handler(int sig, siginfo_t *si, void *uc)
+{
+    /* Note: calling printf() from a signal handler is not safe
+       (and should not be done in production programs), since
+       printf() is not async\-signal\-safe; see signal\-safety(7).
+       Nevertheless, we use printf() here as a simple way of
+       showing that the handler was called. */
+\&
+    printf("Caught signal %d\en", sig);
+    print_siginfo(si);
+    signal(sig, SIG_IGN);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    timer_t            timerid;
+    sigset_t           mask;
+    long long          freq_nanosecs;
+    struct sigevent    sev;
+    struct sigaction   sa;
+    struct itimerspec  its;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <sleep\-secs> <freq\-nanosecs>\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Establish handler for timer signal. */
+\&
+    printf("Establishing handler for signal %d\en", SIG);
+    sa.sa_flags = SA_SIGINFO;
+    sa.sa_sigaction = handler;
+    sigemptyset(&sa.sa_mask);
+    if (sigaction(SIG, &sa, NULL) == \-1)
+        errExit("sigaction");
+\&
+    /* Block timer signal temporarily. */
+\&
+    printf("Blocking signal %d\en", SIG);
+    sigemptyset(&mask);
+    sigaddset(&mask, SIG);
+    if (sigprocmask(SIG_SETMASK, &mask, NULL) == \-1)
+        errExit("sigprocmask");
+\&
+    /* Create the timer. */
+\&
+    sev.sigev_notify = SIGEV_SIGNAL;
+    sev.sigev_signo = SIG;
+    sev.sigev_value.sival_ptr = &timerid;
+    if (timer_create(CLOCKID, &sev, &timerid) == \-1)
+        errExit("timer_create");
+\&
+    printf("timer ID is %#jx\en", (uintmax_t) timerid);
+\&
+    /* Start the timer. */
+\&
+    freq_nanosecs = atoll(argv[2]);
+    its.it_value.tv_sec = freq_nanosecs / 1000000000;
+    its.it_value.tv_nsec = freq_nanosecs % 1000000000;
+    its.it_interval.tv_sec = its.it_value.tv_sec;
+    its.it_interval.tv_nsec = its.it_value.tv_nsec;
+\&
+    if (timer_settime(timerid, 0, &its, NULL) == \-1)
+         errExit("timer_settime");
+\&
+    /* Sleep for a while; meanwhile, the timer may expire
+       multiple times. */
+\&
+    printf("Sleeping for %d seconds\en", atoi(argv[1]));
+    sleep(atoi(argv[1]));
+\&
+    /* Unlock the timer signal, so that timer notification
+       can be delivered. */
+\&
+    printf("Unblocking signal %d\en", SIG);
+    if (sigprocmask(SIG_UNBLOCK, &mask, NULL) == \-1)
+        errExit("sigprocmask");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR clock_gettime (2),
+.BR setitimer (2),
+.BR timer_delete (2),
+.BR timer_getoverrun (2),
+.BR timer_settime (2),
+.BR timerfd_create (2),
+.BR clock_getcpuclockid (3),
+.BR pthread_getcpuclockid (3),
+.BR pthreads (7),
+.BR sigevent (3type),
+.BR signal (7),
+.BR time (7)
diff --git a/man/man2/timer_delete.2 b/man/man2/timer_delete.2
new file mode 100644
index 000000000..bdc2cfa12
--- /dev/null
+++ b/man/man2/timer_delete.2
@@ -0,0 +1,58 @@
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH timer_delete 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+timer_delete \- delete a POSIX per-process timer
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B  #include <time.h>
+.P
+.BI "int timer_delete(timer_t " timerid );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR timer_delete ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+.BR timer_delete ()
+deletes the timer whose ID is given in
+.IR timerid .
+If the timer was armed at the time of this call,
+it is disarmed before being deleted.
+The treatment of any pending signal generated by the deleted timer
+is unspecified.
+.SH RETURN VALUE
+On success,
+.BR timer_delete ()
+returns 0.
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I timerid
+is not a valid timer ID.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+Linux 2.6.
+POSIX.1-2001.
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR timer_create (2),
+.BR timer_getoverrun (2),
+.BR timer_settime (2),
+.BR time (7)
diff --git a/man/man2/timer_getoverrun.2 b/man/man2/timer_getoverrun.2
new file mode 100644
index 000000000..edc1ff6ab
--- /dev/null
+++ b/man/man2/timer_getoverrun.2
@@ -0,0 +1,134 @@
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH timer_getoverrun 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+timer_getoverrun \- get overrun count for a POSIX per-process timer
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B  #include <time.h>
+.P
+.BI "int timer_getoverrun(timer_t " timerid );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR timer_getoverrun ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+.BR timer_getoverrun ()
+returns the "overrun count" for the timer referred to by
+.IR timerid .
+An application can use the overrun count to accurately calculate the number
+of timer expirations that would have occurred over a given time interval.
+Timer overruns can occur both when receiving expiration notifications
+via signals
+.RB ( SIGEV_SIGNAL ),
+and via threads
+.RB ( SIGEV_THREAD ).
+.P
+When expiration notifications are delivered via a signal,
+overruns can occur as follows.
+Regardless of whether or not a real-time signal is used for
+timer notifications,
+the system queues at most one signal per timer.
+(This is the behavior specified by POSIX.1.
+The alternative, queuing one signal for each timer expiration,
+could easily result in overflowing the allowed limits for
+queued signals on the system.)
+Because of system scheduling delays,
+or because the signal may be temporarily blocked,
+there can be a delay between the time when the notification
+signal is generated and the time when it
+is delivered (e.g., caught by a signal handler) or accepted (e.g., using
+.BR sigwaitinfo (2)).
+In this interval, further timer expirations may occur.
+The timer overrun count is the number of additional
+timer expirations that occurred between the time when the signal
+was generated and when it was delivered or accepted.
+.P
+Timer overruns can also occur when expiration notifications
+are delivered via invocation of a thread,
+since there may be an arbitrary delay between an expiration of the timer
+and the invocation of the notification thread,
+and in that delay interval, additional timer expirations may occur.
+.SH RETURN VALUE
+On success,
+.BR timer_getoverrun ()
+returns the overrun count of the specified timer;
+this count may be 0 if no overruns have occurred.
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I timerid
+is not a valid timer ID.
+.SH VERSIONS
+When timer notifications are delivered via signals
+.RB ( SIGEV_SIGNAL ),
+on Linux it is also possible to obtain the overrun count via the
+.I si_overrun
+field of the
+.I siginfo_t
+structure (see
+.BR sigaction (2)).
+This allows an application to avoid the overhead of making
+a system call to obtain the overrun count,
+but is a nonportable extension to POSIX.1.
+.P
+POSIX.1 discusses timer overruns only in the context of
+timer notifications using signals.
+.\" FIXME . Austin bug filed, 11 Feb 09
+.\" https://www.austingroupbugs.net/view.php?id=95
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+Linux 2.6.
+POSIX.1-2001.
+.SH BUGS
+POSIX.1 specifies that if the timer overrun count
+is equal to or greater than an implementation-defined maximum,
+.BR DELAYTIMER_MAX ,
+then
+.BR timer_getoverrun ()
+should return
+.BR DELAYTIMER_MAX .
+However, before Linux 4.19,
+.\" http://bugzilla.kernel.org/show_bug.cgi?id=12665
+if the timer overrun value exceeds the maximum representable integer,
+the counter cycles, starting once more from low values.
+Since Linux 4.19,
+.\" commit 78c9c4dfbf8c04883941445a195276bb4bb92c76
+.BR timer_getoverrun ()
+returns
+.B DELAYTIMER_MAX
+(defined as
+.B INT_MAX
+in
+.IR <limits.h> )
+in this case (and the overrun value is reset to 0).
+.SH EXAMPLES
+See
+.BR timer_create (2).
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR sigaction (2),
+.BR signalfd (2),
+.BR sigwaitinfo (2),
+.BR timer_create (2),
+.BR timer_delete (2),
+.BR timer_settime (2),
+.BR signal (7),
+.BR time (7)
diff --git a/man/man2/timer_gettime.2 b/man/man2/timer_gettime.2
new file mode 100644
index 000000000..42015ca6b
--- /dev/null
+++ b/man/man2/timer_gettime.2
@@ -0,0 +1 @@
+.so man2/timer_settime.2
diff --git a/man/man2/timer_settime.2 b/man/man2/timer_settime.2
new file mode 100644
index 000000000..1f8589874
--- /dev/null
+++ b/man/man2/timer_settime.2
@@ -0,0 +1,187 @@
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH timer_settime 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+timer_settime, timer_gettime \- arm/disarm and fetch
+state of POSIX per-process timer
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B  #include <time.h>
+.P
+.BI "int timer_gettime(timer_t " timerid ", struct itimerspec *" curr_value );
+.BI "int timer_settime(timer_t " timerid ", int " flags ,
+.BI "                  const struct itimerspec *restrict " new_value ,
+.BI "                  struct itimerspec *_Nullable restrict " old_value );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR timer_settime (),
+.BR timer_gettime ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+.BR timer_settime ()
+arms or disarms the timer identified by
+.IR timerid .
+The
+.I new_value
+argument is pointer to an
+.I itimerspec
+structure that specifies the new initial value and
+the new interval for the timer.
+The
+.I itimerspec
+structure is described in
+.BR itimerspec (3type).
+.P
+Each of the substructures of the
+.I itimerspec
+structure is a
+.BR timespec (3)
+structure that allows a time value to be specified
+in seconds and nanoseconds.
+These time values are measured according to the clock
+that was specified when the timer was created by
+.BR timer_create (2).
+.P
+If
+.I new_value\->it_value
+specifies a nonzero value (i.e., either subfield is nonzero), then
+.BR timer_settime ()
+arms (starts) the timer,
+setting it to initially expire at the given time.
+(If the timer was already armed,
+then the previous settings are overwritten.)
+If
+.I new_value\->it_value
+specifies a zero value
+(i.e., both subfields are zero),
+then the timer is disarmed.
+.P
+The
+.I new_value\->it_interval
+field specifies the period of the timer, in seconds and nanoseconds.
+If this field is nonzero, then each time that an armed timer expires,
+the timer is reloaded from the value specified in
+.IR new_value\->it_interval .
+If
+.I new_value\->it_interval
+specifies a zero value,
+then the timer expires just once, at the time specified by
+.IR it_value .
+.P
+By default, the initial expiration time specified in
+.I new_value\->it_value
+is interpreted relative to the current time on the timer's
+clock at the time of the call.
+This can be modified by specifying
+.B TIMER_ABSTIME
+in
+.IR flags ,
+in which case
+.I new_value\->it_value
+is interpreted as an absolute value as measured on the timer's clock;
+that is, the timer will expire when the clock value reaches the
+value specified by
+.IR new_value\->it_value .
+If the specified absolute time has already passed,
+then the timer expires immediately,
+and the overrun count (see
+.BR timer_getoverrun (2))
+will be set correctly.
+.\" By experiment: the overrun count is set correctly, for CLOCK_REALTIME.
+.P
+If the value of the
+.B CLOCK_REALTIME
+clock is adjusted while an absolute timer based on that clock is armed,
+then the expiration of the timer will be appropriately adjusted.
+Adjustments to the
+.B CLOCK_REALTIME
+clock have no effect on relative timers based on that clock.
+.\" Similar remarks might apply with respect to process and thread CPU time
+.\" clocks, but these clocks are not currently (2.6.28) settable on Linux.
+.P
+If
+.I old_value
+is not NULL, then it points to a buffer
+that is used to return the previous interval of the timer (in
+.IR old_value\->it_interval )
+and the amount of time until the timer
+would previously have next expired (in
+.IR old_value\->it_value ).
+.P
+.BR timer_gettime ()
+returns the time until next expiration, and the interval,
+for the timer specified by
+.IR timerid ,
+in the buffer pointed to by
+.IR curr_value .
+The time remaining until the next timer expiration is returned in
+.IR curr_value\->it_value ;
+this is always a relative value, regardless of whether the
+.B TIMER_ABSTIME
+flag was used when arming the timer.
+If the value returned in
+.I curr_value\->it_value
+is zero, then the timer is currently disarmed.
+The timer interval is returned in
+.IR curr_value\->it_interval .
+If the value returned in
+.I curr_value\->it_interval
+is zero, then this is a "one-shot" timer.
+.SH RETURN VALUE
+On success,
+.BR timer_settime ()
+and
+.BR timer_gettime ()
+return 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+These functions may fail with the following errors:
+.TP
+.B EFAULT
+.IR new_value ,
+.IR old_value ,
+or
+.I curr_value
+is not a valid pointer.
+.TP
+.B EINVAL
+.I timerid
+is invalid.
+.\" FIXME . eventually: invalid value in flags
+.P
+.BR timer_settime ()
+may fail with the following errors:
+.TP
+.B EINVAL
+.I new_value.it_value
+is negative; or
+.I new_value.it_value.tv_nsec
+is negative or greater than 999,999,999.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+Linux 2.6.
+POSIX.1-2001.
+.SH EXAMPLES
+See
+.BR timer_create (2).
+.SH SEE ALSO
+.BR timer_create (2),
+.BR timer_getoverrun (2),
+.BR timespec (3),
+.BR time (7)
diff --git a/man/man2/timerfd_create.2 b/man/man2/timerfd_create.2
new file mode 100644
index 000000000..23c399c7d
--- /dev/null
+++ b/man/man2/timerfd_create.2
@@ -0,0 +1,704 @@
+.\" Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH timerfd_create 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+timerfd_create, timerfd_settime, timerfd_gettime \-
+timers that notify via file descriptors
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/timerfd.h>
+.P
+.BI "int timerfd_create(int " clockid ", int " flags );
+.P
+.BI "int timerfd_settime(int " fd ", int " flags ,
+.BI "                    const struct itimerspec *" new_value ,
+.BI "                    struct itimerspec *_Nullable " old_value );
+.BI "int timerfd_gettime(int " fd ", struct itimerspec *" curr_value );
+.fi
+.SH DESCRIPTION
+These system calls create and operate on a timer
+that delivers timer expiration notifications via a file descriptor.
+They provide an alternative to the use of
+.BR setitimer (2)
+or
+.BR timer_create (2),
+with the advantage that the file descriptor may be monitored by
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7).
+.P
+The use of these three system calls is analogous to the use of
+.BR timer_create (2),
+.BR timer_settime (2),
+and
+.BR timer_gettime (2).
+(There is no analog of
+.BR timer_getoverrun (2),
+since that functionality is provided by
+.BR read (2),
+as described below.)
+.\"
+.SS timerfd_create()
+.BR timerfd_create ()
+creates a new timer object,
+and returns a file descriptor that refers to that timer.
+The
+.I clockid
+argument specifies the clock that is used to mark the progress
+of the timer, and must be one of the following:
+.TP
+.B CLOCK_REALTIME
+A settable system-wide real-time clock.
+.TP
+.B CLOCK_MONOTONIC
+A nonsettable monotonically increasing clock that measures time
+from some unspecified point in the past that does not change
+after system startup.
+.TP
+.BR CLOCK_BOOTTIME " (Since Linux 3.15)"
+.\"    commit 4a2378a943f09907fb1ae35c15de917f60289c14
+Like
+.BR CLOCK_MONOTONIC ,
+this is a monotonically increasing clock.
+However, whereas the
+.B CLOCK_MONOTONIC
+clock does not measure the time while a system is suspended, the
+.B CLOCK_BOOTTIME
+clock does include the time during which the system is suspended.
+This is useful for applications that need to be suspend-aware.
+.B CLOCK_REALTIME
+is not suitable for such applications, since that clock is affected
+by discontinuous changes to the system clock.
+.TP
+.BR CLOCK_REALTIME_ALARM " (since Linux 3.11)"
+.\" commit 11ffa9d6065f344a9bd769a2452f26f2f671e5f8
+This clock is like
+.BR CLOCK_REALTIME ,
+but will wake the system if it is suspended.
+The caller must have the
+.B CAP_WAKE_ALARM
+capability in order to set a timer against this clock.
+.TP
+.BR CLOCK_BOOTTIME_ALARM " (since Linux 3.11)"
+.\" commit 11ffa9d6065f344a9bd769a2452f26f2f671e5f8
+This clock is like
+.BR CLOCK_BOOTTIME ,
+but will wake the system if it is suspended.
+The caller must have the
+.B CAP_WAKE_ALARM
+capability in order to set a timer against this clock.
+.P
+See
+.BR clock_getres (2)
+for some further details on the above clocks.
+.P
+The current value of each of these clocks can be retrieved using
+.BR clock_gettime (2).
+.P
+Starting with Linux 2.6.27, the following values may be bitwise ORed in
+.I flags
+to change the behavior of
+.BR timerfd_create ():
+.TP 14
+.B TFD_NONBLOCK
+Set the
+.B O_NONBLOCK
+file status flag on the open file description (see
+.BR open (2))
+referred to by the new file descriptor.
+Using this flag saves extra calls to
+.BR fcntl (2)
+to achieve the same result.
+.TP
+.B TFD_CLOEXEC
+Set the close-on-exec
+.RB ( FD_CLOEXEC )
+flag on the new file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.P
+In Linux versions up to and including 2.6.26,
+.I flags
+must be specified as zero.
+.SS timerfd_settime()
+.BR timerfd_settime ()
+arms (starts) or disarms (stops)
+the timer referred to by the file descriptor
+.IR fd .
+.P
+The
+.I new_value
+argument specifies the initial expiration and interval for the timer.
+The
+.I itimerspec
+structure used for this argument is described in
+.BR itimerspec (3type).
+.P
+.I new_value.it_value
+specifies the initial expiration of the timer,
+in seconds and nanoseconds.
+Setting either field of
+.I new_value.it_value
+to a nonzero value arms the timer.
+Setting both fields of
+.I new_value.it_value
+to zero disarms the timer.
+.P
+Setting one or both fields of
+.I new_value.it_interval
+to nonzero values specifies the period, in seconds and nanoseconds,
+for repeated timer expirations after the initial expiration.
+If both fields of
+.I new_value.it_interval
+are zero, the timer expires just once, at the time specified by
+.IR new_value.it_value .
+.P
+By default,
+the initial expiration time specified in
+.I new_value
+is interpreted relative to the current time
+on the timer's clock at the time of the call (i.e.,
+.I new_value.it_value
+specifies a time relative to the current value of the clock specified by
+.IR clockid ).
+An absolute timeout can be selected via the
+.I flags
+argument.
+.P
+The
+.I flags
+argument is a bit mask that can include the following values:
+.TP
+.B TFD_TIMER_ABSTIME
+Interpret
+.I new_value.it_value
+as an absolute value on the timer's clock.
+The timer will expire when the value of the timer's
+clock reaches the value specified in
+.IR new_value.it_value .
+.TP
+.B TFD_TIMER_CANCEL_ON_SET
+If this flag is specified along with
+.B TFD_TIMER_ABSTIME
+and the clock for this timer is
+.B CLOCK_REALTIME
+or
+.BR CLOCK_REALTIME_ALARM ,
+then mark this timer as cancelable if the real-time clock
+undergoes a discontinuous change
+.RB ( settimeofday (2),
+.BR clock_settime (2),
+or similar).
+When such changes occur, a current or future
+.BR read (2)
+from the file descriptor will fail with the error
+.BR ECANCELED .
+.P
+If the
+.I old_value
+argument is not NULL, then the
+.I itimerspec
+structure that it points to is used to return the setting of the timer
+that was current at the time of the call;
+see the description of
+.BR timerfd_gettime ()
+following.
+.\"
+.SS timerfd_gettime()
+.BR timerfd_gettime ()
+returns, in
+.IR curr_value ,
+an
+.I itimerspec
+structure that contains the current setting of the timer
+referred to by the file descriptor
+.IR fd .
+.P
+The
+.I it_value
+field returns the amount of time
+until the timer will next expire.
+If both fields of this structure are zero,
+then the timer is currently disarmed.
+This field always contains a relative value, regardless of whether the
+.B TFD_TIMER_ABSTIME
+flag was specified when setting the timer.
+.P
+The
+.I it_interval
+field returns the interval of the timer.
+If both fields of this structure are zero,
+then the timer is set to expire just once, at the time specified by
+.IR curr_value.it_value .
+.SS Operating on a timer file descriptor
+The file descriptor returned by
+.BR timerfd_create ()
+supports the following additional operations:
+.TP
+.BR read (2)
+If the timer has already expired one or more times since
+its settings were last modified using
+.BR timerfd_settime (),
+or since the last successful
+.BR read (2),
+then the buffer given to
+.BR read (2)
+returns an unsigned 8-byte integer
+.RI ( uint64_t )
+containing the number of expirations that have occurred.
+(The returned value is in host byte order\[em]that is,
+the native byte order for integers on the host machine.)
+.IP
+If no timer expirations have occurred at the time of the
+.BR read (2),
+then the call either blocks until the next timer expiration,
+or fails with the error
+.B EAGAIN
+if the file descriptor has been made nonblocking
+(via the use of the
+.BR fcntl (2)
+.B F_SETFL
+operation to set the
+.B O_NONBLOCK
+flag).
+.IP
+A
+.BR read (2)
+fails with the error
+.B EINVAL
+if the size of the supplied buffer is less than 8 bytes.
+.IP
+If the associated clock is either
+.B CLOCK_REALTIME
+or
+.BR CLOCK_REALTIME_ALARM ,
+the timer is absolute
+.RB ( TFD_TIMER_ABSTIME ),
+and the flag
+.B TFD_TIMER_CANCEL_ON_SET
+was specified when calling
+.BR timerfd_settime (),
+then
+.BR read (2)
+fails with the error
+.B ECANCELED
+if the real-time clock undergoes a discontinuous change.
+(This allows the reading application to discover
+such discontinuous changes to the clock.)
+.IP
+If the associated clock is either
+.B CLOCK_REALTIME
+or
+.BR CLOCK_REALTIME_ALARM ,
+the timer is absolute
+.RB ( TFD_TIMER_ABSTIME ),
+and the flag
+.B TFD_TIMER_CANCEL_ON_SET
+was
+.I not
+specified when calling
+.BR timerfd_settime (),
+then a discontinuous negative change to the clock (e.g.,
+.BR clock_settime (2))
+may cause
+.BR read (2)
+to unblock, but return a value of 0 (i.e., no bytes read),
+if the clock change occurs after the time expired,
+but before the
+.BR read (2)
+on the file descriptor.
+.TP
+.BR poll (2)
+.TQ
+.BR select (2)
+.TQ
+(and similar)
+The file descriptor is readable
+(the
+.BR select (2)
+.I readfds
+argument; the
+.BR poll (2)
+.B POLLIN
+flag)
+if one or more timer expirations have occurred.
+.IP
+The file descriptor also supports the other file-descriptor
+multiplexing APIs:
+.BR pselect (2),
+.BR ppoll (2),
+and
+.BR epoll (7).
+.TP
+.BR ioctl (2)
+The following timerfd-specific command is supported:
+.RS
+.TP
+.BR TFD_IOC_SET_TICKS " (since Linux 3.17)"
+.\" commit 5442e9fbd7c23172a1c9bc736629cd123a9923f0
+Adjust the number of timer expirations that have occurred.
+The argument is a pointer to a nonzero 8-byte integer
+.RI ( uint64_t *)
+containing the new number of expirations.
+Once the number is set, any waiter on the timer is woken up.
+The only purpose of this command is to restore the expirations
+for the purpose of checkpoint/restore.
+This operation is available only if the kernel was configured with the
+.B CONFIG_CHECKPOINT_RESTORE
+option.
+.RE
+.TP
+.BR close (2)
+When the file descriptor is no longer required it should be closed.
+When all file descriptors associated with the same timer object
+have been closed,
+the timer is disarmed and its resources are freed by the kernel.
+.\"
+.SS fork(2) semantics
+After a
+.BR fork (2),
+the child inherits a copy of the file descriptor created by
+.BR timerfd_create ().
+The file descriptor refers to the same underlying
+timer object as the corresponding file descriptor in the parent,
+and
+.BR read (2)s
+in the child will return information about
+expirations of the timer.
+.\"
+.SS execve(2) semantics
+A file descriptor created by
+.BR timerfd_create ()
+is preserved across
+.BR execve (2),
+and continues to generate timer expirations if the timer was armed.
+.SH RETURN VALUE
+On success,
+.BR timerfd_create ()
+returns a new file descriptor.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.P
+.BR timerfd_settime ()
+and
+.BR timerfd_gettime ()
+return 0 on success;
+on error they return \-1, and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.BR timerfd_create ()
+can fail with the following errors:
+.TP
+.B EINVAL
+The
+.I clockid
+is not valid.
+.TP
+.B EINVAL
+.I flags
+is invalid;
+or, in Linux 2.6.26 or earlier,
+.I flags
+is nonzero.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been
+reached.
+.TP
+.B ENODEV
+Could not mount (internal) anonymous inode device.
+.TP
+.B ENOMEM
+There was insufficient kernel memory to create the timer.
+.TP
+.B EPERM
+.I clockid
+was
+.B CLOCK_REALTIME_ALARM
+or
+.B CLOCK_BOOTTIME_ALARM
+but the caller did not have the
+.B CAP_WAKE_ALARM
+capability.
+.P
+.BR timerfd_settime ()
+and
+.BR timerfd_gettime ()
+can fail with the following errors:
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EFAULT
+.IR new_value ,
+.IR old_value ,
+or
+.I curr_value
+is not a valid pointer.
+.TP
+.B EINVAL
+.I fd
+is not a valid timerfd file descriptor.
+.P
+.BR timerfd_settime ()
+can also fail with the following errors:
+.TP
+.B ECANCELED
+See NOTES.
+.TP
+.B EINVAL
+.I new_value
+is not properly initialized (one of the
+.I tv_nsec
+falls outside the range zero to 999,999,999).
+.TP
+.B EINVAL
+.\" This case only checked since Linux 2.6.29, and Linux 2.2.2[78].some-stable-version.
+.\" In older kernel versions, no check was made for invalid flags.
+.I flags
+is invalid.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.25,
+glibc 2.8.
+.SH NOTES
+Suppose the following scenario for
+.B CLOCK_REALTIME
+or
+.B CLOCK_REALTIME_ALARM
+timer that was created with
+.BR timerfd_create ():
+.IP (1) 5
+The timer has been started
+.RB ( timerfd_settime ())
+with the
+.B TFD_TIMER_ABSTIME
+and
+.B TFD_TIMER_CANCEL_ON_SET
+flags;
+.IP (2)
+A discontinuous change (e.g.,
+.BR settimeofday (2))
+is subsequently made to the
+.B CLOCK_REALTIME
+clock; and
+.IP (3)
+the caller once more calls
+.BR timerfd_settime ()
+to rearm the timer (without first doing a
+.BR read (2)
+on the file descriptor).
+.P
+In this case the following occurs:
+.IP \[bu] 3
+The
+.BR timerfd_settime ()
+returns \-1 with
+.I errno
+set to
+.BR ECANCELED .
+(This enables the caller to know that the previous timer was affected
+by a discontinuous change to the clock.)
+.IP \[bu]
+The timer
+.I "is successfully rearmed"
+with the settings provided in the second
+.BR timerfd_settime ()
+call.
+(This was probably an implementation accident, but won't be fixed now,
+in case there are applications that depend on this behaviour.)
+.SH BUGS
+Currently,
+.\" 2.6.29
+.BR timerfd_create ()
+supports fewer types of clock IDs than
+.BR timer_create (2).
+.SH EXAMPLES
+The following program creates a timer and then monitors its progress.
+The program accepts up to three command-line arguments.
+The first argument specifies the number of seconds for
+the initial expiration of the timer.
+The second argument specifies the interval for the timer, in seconds.
+The third argument specifies the number of times the program should
+allow the timer to expire before terminating.
+The second and third command-line arguments are optional.
+.P
+The following shell session demonstrates the use of the program:
+.P
+.in +4n
+.EX
+.RB "$" " a.out 3 1 100"
+0.000: timer started
+3.000: read: 1; total=1
+4.000: read: 1; total=2
+.BR "\[ha]Z " "                 # type control\-Z to suspend the program"
+[1]+  Stopped                 ./timerfd3_demo 3 1 100
+.RB "$ " "fg" "                # Resume execution after a few seconds"
+a.out 3 1 100
+9.660: read: 5; total=7
+10.000: read: 1; total=8
+11.000: read: 1; total=9
+.BR "\[ha]C " "                 # type control\-C to suspend the program"
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (timerfd_create.c)
+.EX
+.\" The commented out code here is what we currently need until
+.\" the required stuff is in glibc
+.\"
+.\"
+.\"/* Link with \-lrt */
+.\"#define _GNU_SOURCE
+.\"#include <sys/syscall.h>
+.\"#include <unistd.h>
+.\"#include <time.h>
+.\"#if defined(__i386__)
+.\"#define __NR_timerfd_create 322
+.\"#define __NR_timerfd_settime 325
+.\"#define __NR_timerfd_gettime 326
+.\"#endif
+.\"
+.\"static int
+.\"timerfd_create(int clockid, int flags)
+.\"{
+.\"    return syscall(__NR_timerfd_create, clockid, flags);
+.\"}
+.\"
+.\"static int
+.\"timerfd_settime(int fd, int flags, struct itimerspec *new_value,
+.\"        struct itimerspec *curr_value)
+.\"{
+.\"    return syscall(__NR_timerfd_settime, fd, flags, new_value,
+.\"                   curr_value);
+.\"}
+.\"
+.\"static int
+.\"timerfd_gettime(int fd, struct itimerspec *curr_value)
+.\"{
+.\"    return syscall(__NR_timerfd_gettime, fd, curr_value);
+.\"}
+.\"
+.\"#define TFD_TIMER_ABSTIME (1 << 0)
+.\"
+.\"////////////////////////////////////////////////////////////
+#include <err.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/timerfd.h>
+#include <time.h>
+#include <unistd.h>
+\&
+static void
+print_elapsed_time(void)
+{
+    int                     secs, nsecs;
+    static int              first_call = 1;
+    struct timespec         curr;
+    static struct timespec  start;
+\&
+    if (first_call) {
+        first_call = 0;
+        if (clock_gettime(CLOCK_MONOTONIC, &start) == \-1)
+            err(EXIT_FAILURE, "clock_gettime");
+    }
+\&
+    if (clock_gettime(CLOCK_MONOTONIC, &curr) == \-1)
+        err(EXIT_FAILURE, "clock_gettime");
+\&
+    secs = curr.tv_sec \- start.tv_sec;
+    nsecs = curr.tv_nsec \- start.tv_nsec;
+    if (nsecs < 0) {
+        secs\-\-;
+        nsecs += 1000000000;
+    }
+    printf("%d.%03d: ", secs, (nsecs + 500000) / 1000000);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int                fd;
+    ssize_t            s;
+    uint64_t           exp, tot_exp, max_exp;
+    struct timespec    now;
+    struct itimerspec  new_value;
+\&
+    if (argc != 2 && argc != 4) {
+        fprintf(stderr, "%s init\-secs [interval\-secs max\-exp]\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (clock_gettime(CLOCK_REALTIME, &now) == \-1)
+        err(EXIT_FAILURE, "clock_gettime");
+\&
+    /* Create a CLOCK_REALTIME absolute timer with initial
+       expiration and interval as specified in command line. */
+\&
+    new_value.it_value.tv_sec = now.tv_sec + atoi(argv[1]);
+    new_value.it_value.tv_nsec = now.tv_nsec;
+    if (argc == 2) {
+        new_value.it_interval.tv_sec = 0;
+        max_exp = 1;
+    } else {
+        new_value.it_interval.tv_sec = atoi(argv[2]);
+        max_exp = atoi(argv[3]);
+    }
+    new_value.it_interval.tv_nsec = 0;
+\&
+    fd = timerfd_create(CLOCK_REALTIME, 0);
+    if (fd == \-1)
+        err(EXIT_FAILURE, "timerfd_create");
+\&
+    if (timerfd_settime(fd, TFD_TIMER_ABSTIME, &new_value, NULL) == \-1)
+        err(EXIT_FAILURE, "timerfd_settime");
+\&
+    print_elapsed_time();
+    printf("timer started\en");
+\&
+    for (tot_exp = 0; tot_exp < max_exp;) {
+        s = read(fd, &exp, sizeof(uint64_t));
+        if (s != sizeof(uint64_t))
+            err(EXIT_FAILURE, "read");
+\&
+        tot_exp += exp;
+        print_elapsed_time();
+        printf("read: %" PRIu64 "; total=%" PRIu64 "\en", exp, tot_exp);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR eventfd (2),
+.BR poll (2),
+.BR read (2),
+.BR select (2),
+.BR setitimer (2),
+.BR signalfd (2),
+.BR timer_create (2),
+.BR timer_gettime (2),
+.BR timer_settime (2),
+.BR timespec (3),
+.BR epoll (7),
+.BR time (7)
diff --git a/man/man2/timerfd_gettime.2 b/man/man2/timerfd_gettime.2
new file mode 100644
index 000000000..6d1294048
--- /dev/null
+++ b/man/man2/timerfd_gettime.2
@@ -0,0 +1 @@
+.so man2/timerfd_create.2
diff --git a/man/man2/timerfd_settime.2 b/man/man2/timerfd_settime.2
new file mode 100644
index 000000000..6d1294048
--- /dev/null
+++ b/man/man2/timerfd_settime.2
@@ -0,0 +1 @@
+.so man2/timerfd_create.2
diff --git a/man/man2/times.2 b/man/man2/times.2
new file mode 100644
index 000000000..7e85beb6e
--- /dev/null
+++ b/man/man2/times.2
@@ -0,0 +1,222 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt (michael@moria.de)
+.\" Modified Sat Jul 24 14:29:17 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 961203 and 001211 and 010326 by aeb@cwi.nl
+.\" Modified 001213 by Michael Haardt (michael@moria.de)
+.\" Modified 13 Jun 02, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added note on nonstandard behavior when SIGCHLD is ignored.
+.\" Modified 2004-11-16, mtk, Noted that the nonconformance when
+.\"	SIGCHLD is being ignored is fixed in Linux 2.6.9; other minor changes
+.\" Modified 2004-12-08, mtk, in Linux 2.6 times() return value changed
+.\" 2005-04-13, mtk
+.\"	Added notes on nonstandard behavior: Linux allows 'buf' to
+.\"	be NULL, but POSIX.1 doesn't specify this and it's nonportable.
+.\"
+.TH times 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+times \- get process times
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/times.h>
+.P
+.BI "clock_t times(struct tms *" buf );
+.fi
+.SH DESCRIPTION
+.BR times ()
+stores the current process times in the
+.I "struct tms"
+that
+.I buf
+points to.
+The
+.I struct tms
+is as defined in
+.IR <sys/times.h> :
+.P
+.in +4n
+.EX
+struct tms {
+    clock_t tms_utime;  /* user time */
+    clock_t tms_stime;  /* system time */
+    clock_t tms_cutime; /* user time of children */
+    clock_t tms_cstime; /* system time of children */
+};
+.EE
+.in
+.P
+The
+.I tms_utime
+field contains the CPU time spent executing instructions
+of the calling process.
+The
+.I tms_stime
+field contains the CPU time spent executing inside the kernel
+while performing tasks on behalf of the calling process.
+.P
+The
+.I tms_cutime
+field contains the sum of the
+.I tms_utime
+and
+.I tms_cutime
+values for all waited-for terminated children.
+The
+.I tms_cstime
+field contains the sum of the
+.I tms_stime
+and
+.I tms_cstime
+values for all waited-for terminated children.
+.P
+Times for terminated children (and their descendants)
+are added in at the moment
+.BR wait (2)
+or
+.BR waitpid (2)
+returns their process ID.
+In particular,
+times of grandchildren
+that the children did not wait for are never seen.
+.P
+All times reported are in clock ticks.
+.SH RETURN VALUE
+.BR times ()
+returns the number of clock ticks that have elapsed since
+an arbitrary point in the past.
+The return value may overflow the possible range of type
+.IR clock_t .
+On error,
+\fI(clock_t)\ \-1\fP is returned,
+and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I tms
+points outside the process's address space.
+.SH VERSIONS
+On Linux,
+the
+.I buf
+argument can be specified as NULL,
+with the result that
+.BR times ()
+just returns a function result.
+However,
+POSIX does not specify this behavior,
+and most
+other UNIX implementations require a non-NULL value for
+.IR buf .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001,
+SVr4,
+4.3BSD.
+.P
+In POSIX.1-1996 the symbol \fBCLK_TCK\fP (defined in
+.IR <time.h> )
+is mentioned as obsolescent.
+It is obsolete now.
+.P
+Before Linux 2.6.9,
+if the disposition of
+.B SIGCHLD
+is set to
+.BR SIG_IGN ,
+then the times of terminated children
+are automatically included in the
+.I tms_cstime
+and
+.I tms_cutime
+fields,
+although POSIX.1-2001 says that this should happen
+only if the calling process
+.BR wait (2)s
+on its children.
+This nonconformance is rectified in Linux 2.6.9 and later.
+.\" See the description of times() in XSH, which says:
+.\"	The times of a terminated child process are included... when wait()
+.\"	or waitpid() returns the process ID of this terminated child.
+.P
+On Linux,
+the \[lq]arbitrary point in the past\[rq]
+from which the return value of
+.BR times ()
+is measured has varied across kernel versions.
+On Linux 2.4 and earlier,
+this point is the moment the system was booted.
+Since Linux 2.6,
+this point is \fI(2\[ha]32/HZ) \- 300\fP
+seconds before system boot time.
+This variability across kernel versions (and across UNIX implementations),
+combined with the fact that the returned value may overflow the range of
+.IR clock_t ,
+means that a portable application would be wise to avoid using this value.
+To measure changes in elapsed time,
+use
+.BR clock_gettime (2)
+instead.
+.\" .P
+.\" On older systems the number of clock ticks per second is given
+.\" by the variable HZ.
+.P
+SVr1-3 returns
+.I long
+and the struct members are of type
+.I time_t
+although they store clock ticks,
+not seconds since the Epoch.
+V7 used
+.I long
+for the struct members,
+because it had no type
+.I time_t
+yet.
+.SH NOTES
+The number of clock ticks per second can be obtained using:
+.P
+.in +4n
+.EX
+sysconf(_SC_CLK_TCK);
+.EE
+.in
+.P
+Note that
+.BR clock (3)
+also returns a value of type
+.IR clock_t ,
+but this value is measured in units of
+.BR CLOCKS_PER_SEC ,
+not the clock ticks used by
+.BR times ().
+.SH BUGS
+A limitation of the Linux system call conventions on some architectures
+(notably i386) means that on Linux 2.6 there is a small time window
+(41 seconds) soon after boot when
+.BR times ()
+can return \-1,
+falsely indicating that an error occurred.
+The same problem can occur when the return value wraps past
+the maximum value that can be stored in
+.BR clock_t .
+.\" The problem is that a syscall return of -4095 to -1
+.\" is interpreted by glibc as an error, and the wrapper converts
+.\" the return value to -1.
+.\" http://marc.info/?l=linux-kernel&m=119447727031225&w=2
+.\" "compat_sys_times() bogus until jiffies >= 0"
+.\" November 2007
+.SH SEE ALSO
+.BR time (1),
+.BR getrusage (2),
+.BR wait (2),
+.BR clock (3),
+.BR sysconf (3),
+.BR time (7)
diff --git a/man/man2/tkill.2 b/man/man2/tkill.2
new file mode 100644
index 000000000..9bbf722fe
--- /dev/null
+++ b/man/man2/tkill.2
@@ -0,0 +1,130 @@
+.\" Copyright (C) 2008 Michael Kerrisk <tmk.manpages@gmail.com>
+.\" and Copyright 2003 Abhijit Menon-Sen <ams@wiw.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2004-05-31, added tgkill, ahu, aeb
+.\" 2008-01-15 mtk -- rewrote DESCRIPTION
+.\"
+.TH tkill 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tkill, tgkill \- send a signal to a thread
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <signal.h>" "           /* Definition of " SIG* " constants */"
+.BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "[[deprecated]] int syscall(SYS_tkill, pid_t " tid ", int " sig );
+.P
+.B #include <signal.h>
+.P
+.BI "int tgkill(pid_t " tgid ", pid_t " tid ", int " sig );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR tkill (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR tgkill ()
+sends the signal
+.I sig
+to the thread with the thread ID
+.I tid
+in the thread group
+.IR tgid .
+(By contrast,
+.BR kill (2)
+can be used to send a signal only to a process (i.e., thread group)
+as a whole, and the signal will be delivered to an arbitrary
+thread within that process.)
+.P
+.BR tkill ()
+is an obsolete predecessor to
+.BR tgkill ().
+It allows only the target thread ID to be specified,
+which may result in the wrong thread being signaled if a thread
+terminates and its thread ID is recycled.
+Avoid using this system call.
+.\" FIXME Maybe say something about the following:
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=12889
+.\"
+.\" Quoting Rich Felker <bugdal@aerifal.cx>:
+.\"
+.\" There is a race condition in pthread_kill: it is possible that,
+.\" between the time pthread_kill reads the pid/tid from the target
+.\" thread descriptor and the time it makes the tgkill syscall,
+.\" the target thread terminates and the same tid gets assigned
+.\" to a new thread in the same process.
+.\"
+.\" (The tgkill syscall was designed to eliminate a similar race
+.\" condition in tkill, but it only succeeded in eliminating races
+.\" where the tid gets reused in a different process, and does not
+.\" help if the same tid gets assigned to a new thread in the
+.\" same process.)
+.\"
+.\" The only solution I can see is to introduce a mutex that ensures
+.\" that a thread cannot exit while pthread_kill is being called on it.
+.\"
+.\" Note that in most real-world situations, like almost all race
+.\" conditions, this one will be extremely rare. To make it
+.\" measurable, one could exhaust all but 1-2 available pid values,
+.\" possibly by lowering the max pid parameter in /proc, forcing
+.\" the same tid to be reused rapidly.
+.P
+These are the raw system call interfaces, meant for internal
+thread library use.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and \fIerrno\fP
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The
+.B RLIMIT_SIGPENDING
+resource limit was reached and
+.I sig
+is a real-time signal.
+.TP
+.B EAGAIN
+Insufficient kernel memory was available and
+.I sig
+is a real-time signal.
+.TP
+.B EINVAL
+An invalid thread ID, thread group ID, or signal was specified.
+.TP
+.B EPERM
+Permission denied.
+For the required permissions, see
+.BR kill (2).
+.TP
+.B ESRCH
+No process with the specified thread ID (and thread group ID) exists.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.TP
+.BR tkill ()
+Linux 2.4.19 / 2.5.4.
+.TP
+.BR tgkill ()
+Linux 2.5.75,
+glibc 2.30.
+.SH NOTES
+See the description of
+.B CLONE_THREAD
+in
+.BR clone (2)
+for an explanation of thread groups.
+.SH SEE ALSO
+.BR clone (2),
+.BR gettid (2),
+.BR kill (2),
+.BR rt_sigqueueinfo (2)
diff --git a/man/man2/truncate.2 b/man/man2/truncate.2
new file mode 100644
index 000000000..ac72f8820
--- /dev/null
+++ b/man/man2/truncate.2
@@ -0,0 +1,251 @@
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)truncate.2	6.9 (Berkeley) 3/10/91
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 1998-12-21 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2002-01-07 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2002-04-06 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH truncate 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+truncate, ftruncate \- truncate a file to a specified length
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int truncate(const char *" path ", off_t " length );
+.BI "int ftruncate(int " fd ", off_t " length );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR truncate ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.P
+.BR ftruncate ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.3.5: */ _POSIX_C_SOURCE >= 200112L
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR truncate ()
+and
+.BR ftruncate ()
+functions cause the regular file named by
+.I path
+or referenced by
+.I fd
+to be truncated to a size of precisely
+.I length
+bytes.
+.P
+If the file previously was larger than this size, the extra data is lost.
+If the file previously was shorter, it is extended, and
+the extended part reads as null bytes (\[aq]\e0\[aq]).
+.P
+The file offset is not changed.
+.P
+If the size changed, then the st_ctime and st_mtime fields
+(respectively, time of last status change and
+time of last modification; see
+.BR inode (7))
+for the file are updated,
+and the set-user-ID and set-group-ID mode bits may be cleared.
+.P
+With
+.BR ftruncate (),
+the file must be open for writing; with
+.BR truncate (),
+the file must be writable.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+For
+.BR truncate ():
+.TP
+.B EACCES
+Search permission is denied for a component of the path prefix,
+or the named file is not writable by the user.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EFAULT
+The argument
+.I path
+points outside the process's allocated address space.
+.TP
+.B EFBIG
+The argument
+.I length
+is larger than the maximum file size. (XSI)
+.TP
+.B EINTR
+While blocked waiting to complete,
+the call was interrupted by a signal handler; see
+.BR fcntl (2)
+and
+.BR signal (7).
+.TP
+.B EINVAL
+The argument
+.I length
+is negative or larger than the maximum file size.
+.TP
+.B EIO
+An I/O error occurred updating the inode.
+.TP
+.B EISDIR
+The named file is a directory.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in translating the pathname.
+.TP
+.B ENAMETOOLONG
+A component of a pathname exceeded 255 characters,
+or an entire pathname exceeded 1023 characters.
+.TP
+.B ENOENT
+The named file does not exist.
+.TP
+.B ENOTDIR
+A component of the path prefix is not a directory.
+.TP
+.B EPERM
+.\" This happens for at least MSDOS and VFAT filesystems
+.\" on kernel 2.6.13
+The underlying filesystem does not support extending
+a file beyond its current size.
+.TP
+.B EPERM
+The operation was prevented by a file seal; see
+.BR fcntl (2).
+.TP
+.B EROFS
+The named file resides on a read-only filesystem.
+.TP
+.B ETXTBSY
+The file is an executable file that is being executed.
+.P
+For
+.BR ftruncate ()
+the same errors apply, but instead of things that can be wrong with
+.IR path ,
+we now have things that can be wrong with the file descriptor,
+.IR fd :
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.BR EBADF " or " EINVAL
+.I fd
+is not open for writing.
+.TP
+.B EINVAL
+.I fd
+does not reference a regular file or a POSIX shared memory object.
+.TP
+.BR EINVAL " or " EBADF
+The file descriptor
+.I fd
+is not open for writing.
+POSIX permits, and portable applications should handle,
+either error for this case.
+(Linux produces
+.BR EINVAL .)
+.SH VERSIONS
+The details in DESCRIPTION are for XSI-compliant systems.
+For non-XSI-compliant systems, the POSIX standard allows
+two behaviors for
+.BR ftruncate ()
+when
+.I length
+exceeds the file length
+(note that
+.BR truncate ()
+is not specified at all in such an environment):
+either returning an error, or extending the file.
+Like most UNIX implementations, Linux follows the XSI requirement
+when dealing with native filesystems.
+However, some nonnative filesystems do not permit
+.BR truncate ()
+and
+.BR ftruncate ()
+to be used to extend a file beyond its current length:
+a notable example on Linux is VFAT.
+.\" At the very least: OSF/1, Solaris 7, and FreeBSD conform, mtk, Jan 2002
+.P
+On some 32-bit architectures,
+the calling signature for these system calls differ,
+for the reasons described in
+.BR syscall (2).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001,
+4.4BSD, SVr4 (first appeared in 4.2BSD).
+.\" POSIX.1-1996 has
+.\" .BR ftruncate ().
+.\" POSIX.1-2001 also has
+.\" .BR truncate (),
+.\" as an XSI extension.
+.\" .P
+.\" SVr4 documents additional
+.\" .BR truncate ()
+.\" error conditions EMFILE, EMULTIHP, ENFILE, ENOLINK.  SVr4 documents for
+.\" .BR ftruncate ()
+.\" an additional EAGAIN error condition.
+.P
+The original Linux
+.BR truncate ()
+and
+.BR ftruncate ()
+system calls were not designed to handle large file offsets.
+Consequently, Linux 2.4 added
+.BR truncate64 ()
+and
+.BR ftruncate64 ()
+system calls that handle large files.
+However, these details can be ignored by applications using glibc, whose
+wrapper functions transparently employ the more recent system calls
+where they are available.
+.SH NOTES
+.BR ftruncate ()
+can also be used to set the size of a POSIX shared memory object; see
+.BR shm_open (3).
+.SH BUGS
+A header file bug in glibc 2.12 meant that the minimum value of
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=12037
+.B _POSIX_C_SOURCE
+required to expose the declaration of
+.BR ftruncate ()
+was 200809L instead of 200112L.
+This has been fixed in later glibc versions.
+.SH SEE ALSO
+.BR truncate (1),
+.BR open (2),
+.BR stat (2),
+.BR path_resolution (7)
diff --git a/man/man2/truncate64.2 b/man/man2/truncate64.2
new file mode 100644
index 000000000..2ed34f1ed
--- /dev/null
+++ b/man/man2/truncate64.2
@@ -0,0 +1 @@
+.so man2/truncate.2
diff --git a/man/man2/tuxcall.2 b/man/man2/tuxcall.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/tuxcall.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/ugetrlimit.2 b/man/man2/ugetrlimit.2
new file mode 100644
index 000000000..df6d7362a
--- /dev/null
+++ b/man/man2/ugetrlimit.2
@@ -0,0 +1 @@
+.so man2/getrlimit.2
diff --git a/man/man2/umask.2 b/man/man2/umask.2
new file mode 100644
index 000000000..939f258e7
--- /dev/null
+++ b/man/man2/umask.2
@@ -0,0 +1,149 @@
+.\" Copyright (c) 2006, 2008, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" (A few fragments remain from an earlier (1992) version written in
+.\" 1992 by Drew Eckhardt <drew@cs.colorado.edu>.)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified Sat Jul 24 12:51:53 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 22:39:04 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Thu May  1 06:05:54 UTC 1997 by Nicolás Lichtmaier
+.\"  <nick@debian.com> with Lars Wirzenius <liw@iki.fi> suggestion
+.\" 2006-05-13, mtk, substantial rewrite of description of 'mask'
+.\" 2008-01-09, mtk, a few rewrites and additions.
+.TH umask 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+umask \- set file mode creation mask
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/stat.h>
+.P
+.BI "mode_t umask(mode_t " mask );
+.fi
+.SH DESCRIPTION
+.BR umask ()
+sets the calling process's file mode creation mask (umask) to
+.I mask
+& 0777 (i.e., only the file permission bits of
+.I mask
+are used), and returns the previous value of the mask.
+.P
+The umask is used by
+.BR open (2),
+.BR mkdir (2),
+and other system calls that create files
+.\" e.g., mkfifo(), creat(), mknod(), sem_open(), mq_open(), shm_open()
+.\" but NOT the System V IPC *get() calls
+to modify the permissions placed on newly created files or directories.
+Specifically, permissions in the umask are turned off from
+the
+.I mode
+argument to
+.BR open (2)
+and
+.BR mkdir (2).
+.P
+Alternatively, if the parent directory has a default ACL (see
+.BR acl (5)),
+the umask is ignored, the default ACL is inherited,
+the permission bits are set based on the inherited ACL,
+and permission bits absent in the
+.I mode
+argument are turned off.
+For example, the following default ACL is equivalent to a umask of 022:
+.P
+.in +4n
+.EX
+u::rwx,g::r-x,o::r-x
+.EE
+.in
+.P
+Combining the effect of this default ACL with a
+.I mode
+argument of 0666 (rw-rw-rw-), the resulting file permissions would be 0644
+(rw-r--r--).
+.P
+The constants that should be used to specify
+.I mask
+are described in
+.BR inode (7).
+.P
+The typical default value for the process umask is
+.BR S_IWGRP " | " S_IWOTH
+(octal 022).
+In the usual case where the
+.I mode
+argument to
+.BR open (2)
+is specified as:
+.P
+.in +4n
+.EX
+.BR S_IRUSR " | " S_IWUSR " | " S_IRGRP " | " S_IWGRP " | " S_IROTH " | " S_IWOTH
+.EE
+.in
+.P
+(octal 0666) when creating a new file, the permissions on the
+resulting file will be:
+.P
+.in +4n
+.EX
+.BR S_IRUSR " | " S_IWUSR " | " S_IRGRP " | " S_IROTH
+.EE
+.in
+.P
+(because 0666 & \[ti]022 = 0644; i.e. rw\-r\-\-r\-\-).
+.SH RETURN VALUE
+This system call always succeeds and the previous value of the mask
+is returned.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH NOTES
+A child process created via
+.BR fork (2)
+inherits its parent's umask.
+The umask is left unchanged by
+.BR execve (2).
+.P
+It is impossible to use
+.BR umask ()
+to fetch a process's umask without at the same time changing it.
+A second call to
+.BR umask ()
+would then be needed to restore the umask.
+The nonatomicity of these two steps provides the potential
+for races in multithreaded programs.
+.P
+Since Linux 4.7, the umask of any process can be viewed via the
+.I Umask
+field of
+.IR /proc/ pid /status .
+Inspecting this field in
+.I /proc/self/status
+allows a process to retrieve its umask without at the same time changing it.
+.P
+The umask setting also affects the permissions assigned to POSIX IPC objects
+.RB ( mq_open (3),
+.BR sem_open (3),
+.BR shm_open (3)),
+FIFOs
+.RB ( mkfifo (3)),
+and UNIX domain sockets
+.RB ( unix (7))
+created by the process.
+The umask does not affect the permissions assigned
+to System\ V IPC objects created by the process (using
+.BR msgget (2),
+.BR semget (2),
+.BR shmget (2)).
+.SH SEE ALSO
+.BR chmod (2),
+.BR mkdir (2),
+.BR open (2),
+.BR stat (2),
+.BR acl (5)
diff --git a/man/man2/umount.2 b/man/man2/umount.2
new file mode 100644
index 000000000..6decda265
--- /dev/null
+++ b/man/man2/umount.2
@@ -0,0 +1,214 @@
+.\" Copyright (C) 1993 Rickard E. Faith <faith@cs.unc.edu>
+.\" and Copyright (C) 1994 Andries E. Brouwer <aeb@cwi.nl>
+.\" and Copyright (C) 2002, 2005 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2008-10-06, mtk: Created this as a new page by splitting
+.\"     umount/umount2 material out of mount.2
+.\"
+.TH umount 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+umount, umount2 \- unmount filesystem
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <sys/mount.h>"
+.P
+.BI "int umount(const char *" target );
+.BI "int umount2(const char *" target ", int " flags );
+.fi
+.SH DESCRIPTION
+.BR umount ()
+and
+.BR umount2 ()
+remove the attachment of the (topmost) filesystem mounted on
+.IR target .
+.\" Note: the kernel naming differs from the glibc naming
+.\" umount2 is the glibc name for what the kernel now calls umount
+.\" and umount is the glibc name for oldumount
+.P
+Appropriate privilege (Linux: the
+.B CAP_SYS_ADMIN
+capability) is required to unmount filesystems.
+.P
+Linux 2.1.116 added the
+.BR umount2 ()
+system call, which, like
+.BR umount (),
+unmounts a target, but allows additional
+.I flags
+controlling the behavior of the operation:
+.TP
+.BR MNT_FORCE " (since Linux 2.1.116)"
+Ask the filesystem to abort pending requests before attempting the
+unmount.
+This may allow the unmount to complete without waiting
+for an inaccessible server, but could cause data loss.
+If, after aborting requests,
+some processes still have active references to the filesystem,
+the unmount will still fail.
+As at Linux 4.12,
+.B MNT_FORCE
+is supported only on the following filesystems:
+9p (since Linux 2.6.16),
+ceph (since Linux 2.6.34),
+cifs (since Linux 2.6.12),
+fuse (since Linux 2.6.16),
+lustre (since Linux 3.11),
+and NFS (since Linux 2.1.116).
+.TP
+.BR MNT_DETACH " (since Linux 2.4.11)"
+Perform a lazy unmount: make the mount unavailable for new
+accesses, immediately disconnect the filesystem and all filesystems
+mounted below it from each other and from the mount table, and
+actually perform the unmount when the mount ceases to be busy.
+.TP
+.BR MNT_EXPIRE " (since Linux 2.6.8)"
+Mark the mount as expired.
+If a mount is not currently in use, then an initial call to
+.BR umount2 ()
+with this flag fails with the error
+.BR EAGAIN ,
+but marks the mount as expired.
+The mount remains expired as long as it isn't accessed
+by any process.
+A second
+.BR umount2 ()
+call specifying
+.B MNT_EXPIRE
+unmounts an expired mount.
+This flag cannot be specified with either
+.B MNT_FORCE
+or
+.BR MNT_DETACH .
+.TP
+.BR UMOUNT_NOFOLLOW " (since Linux 2.6.34)"
+.\" Later added to Linux 2.6.33-stable
+Don't dereference
+.I target
+if it is a symbolic link.
+This flag allows security problems to be avoided in set-user-ID-\fIroot\fP
+programs that allow unprivileged users to unmount filesystems.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The error values given below result from filesystem type independent
+errors.
+Each filesystem type may have its own special errors and its
+own special behavior.
+See the Linux kernel source code for details.
+.TP
+.B EAGAIN
+A call to
+.BR umount2 ()
+specifying
+.B MNT_EXPIRE
+successfully marked an unbusy filesystem as expired.
+.TP
+.B EBUSY
+.I target
+could not be unmounted because it is busy.
+.TP
+.B EFAULT
+.I target
+points outside the user address space.
+.TP
+.B EINVAL
+.I target
+is not a mount point.
+.TP
+.B EINVAL
+.I target
+is locked; see
+.BR mount_namespaces (7).
+.TP
+.B EINVAL
+.BR umount2 ()
+was called with
+.B MNT_EXPIRE
+and either
+.B MNT_DETACH
+or
+.BR MNT_FORCE .
+.TP
+.BR EINVAL " (since Linux 2.6.34)"
+.BR umount2 ()
+was called with an invalid flag value in
+.IR flags .
+.TP
+.B ENAMETOOLONG
+A pathname was longer than
+.BR MAXPATHLEN .
+.TP
+.B ENOENT
+A pathname was empty or had a nonexistent component.
+.TP
+.B ENOMEM
+The kernel could not allocate a free page to copy filenames or data into.
+.TP
+.B EPERM
+The caller does not have the required privileges.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+.B MNT_DETACH
+and
+.B MNT_EXPIRE
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=10092
+are available since glibc 2.11.
+.P
+The original
+.BR umount ()
+function was called as \fIumount(device)\fP and would return
+.B ENOTBLK
+when called with something other than a block device.
+In Linux 0.98p4, a call \fIumount(dir)\fP was added, in order to
+support anonymous devices.
+In Linux 2.3.99-pre7, the call \fIumount(device)\fP was removed,
+leaving only \fIumount(dir)\fP (since now devices can be mounted
+in more than one place, so specifying the device does not suffice).
+.SH NOTES
+.SS umount() and shared mounts
+Shared mounts cause any mount activity on a mount, including
+.BR umount ()
+operations, to be forwarded to every shared mount in the
+peer group and every slave mount of that peer group.
+This means that
+.BR umount ()
+of any peer in a set of shared mounts will cause all of its
+peers to be unmounted and all of their slaves to be unmounted as well.
+.P
+This propagation of unmount activity can be particularly surprising
+on systems where every mount is shared by default.
+On such systems,
+recursively bind mounting the root directory of the filesystem
+onto a subdirectory and then later unmounting that subdirectory with
+.B MNT_DETACH
+will cause every mount in the mount namespace to be lazily unmounted.
+.P
+To ensure
+.BR umount ()
+does not propagate in this fashion,
+the mount may be remounted using a
+.BR mount (2)
+call with a
+.I mount_flags
+argument that includes both
+.B MS_REC
+and
+.B MS_PRIVATE
+prior to
+.BR umount ()
+being called.
+.SH SEE ALSO
+.BR mount (2),
+.BR mount_namespaces (7),
+.BR path_resolution (7),
+.BR mount (8),
+.BR umount (8)
diff --git a/man/man2/umount2.2 b/man/man2/umount2.2
new file mode 100644
index 000000000..84ea41905
--- /dev/null
+++ b/man/man2/umount2.2
@@ -0,0 +1 @@
+.so man2/umount.2
diff --git a/man/man2/uname.2 b/man/man2/uname.2
new file mode 100644
index 000000000..99178fc22
--- /dev/null
+++ b/man/man2/uname.2
@@ -0,0 +1,134 @@
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2007-07-05 mtk: Added details on underlying system call interfaces
+.\"
+.TH uname 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+uname \- get name and information about current kernel
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/utsname.h>
+.P
+.BI "int uname(struct utsname *" buf );
+.fi
+.SH DESCRIPTION
+.BR uname ()
+returns system information in the structure pointed to by
+.IR buf .
+The
+.I utsname
+struct is defined in
+.IR <sys/utsname.h> :
+.P
+.in +4n
+.EX
+struct utsname {
+    char sysname[];    /* Operating system name (e.g., "Linux") */
+    char nodename[];   /* Name within communications network
+                          to which the node is attached, if any */
+    char release[];    /* Operating system release
+                          (e.g., "2.6.28") */
+    char version[];    /* Operating system version */
+    char machine[];    /* Hardware type identifier */
+#ifdef _GNU_SOURCE
+    char domainname[]; /* NIS or YP domain name */
+#endif
+};
+.EE
+.in
+.P
+The length of the arrays in a
+.I struct utsname
+is unspecified (see NOTES);
+the fields are terminated by a null byte (\[aq]\e0\[aq]).
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I buf
+is not valid.
+.SH VERSIONS
+The
+.I domainname
+member (the NIS or YP domain name) is a GNU extension.
+.P
+The length of the fields in the struct varies.
+Some operating systems
+or libraries use a hardcoded 9 or 33 or 65 or 257.
+Other systems use
+.B SYS_NMLN
+or
+.B _SYS_NMLN
+or
+.B UTSLEN
+or
+.BR _UTSNAME_LENGTH .
+Clearly, it is a bad
+idea to use any of these constants; just use sizeof(...).
+SVr4 uses 257, "to support Internet hostnames"
+\[em] this is the largest value likely to be encountered in the wild.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD.
+.SS C library/kernel differences
+Over time, increases in the size of the
+.I utsname
+structure have led to three successive versions of
+.BR uname ():
+.IR sys_olduname ()
+(slot
+.IR __NR_oldolduname ),
+.IR sys_uname ()
+(slot
+.IR __NR_olduname ),
+and
+.IR sys_newuname ()
+(slot
+.IR __NR_uname) .
+The first one
+.\" That was back before Linux 1.0
+used length 9 for all fields;
+the second
+.\" That was also back before Linux 1.0
+used 65;
+the third also uses 65 but adds the
+.I domainname
+field.
+The glibc
+.BR uname ()
+wrapper function hides these details from applications,
+invoking the most recent version of the system call provided by the kernel.
+.SH NOTES
+The kernel has the name, release, version, and supported machine type built in.
+Conversely, the
+.I nodename
+field is configured by the administrator to match the network
+(this is what the BSD historically calls the "hostname",
+and is set via
+.BR sethostname (2)).
+Similarly, the
+.I domainname
+field is set via
+.BR setdomainname (2).
+.P
+Part of the utsname information is also accessible via
+.IR /proc/sys/kernel/ { ostype ,
+.IR hostname ,
+.IR osrelease ,
+.IR version ,
+.IR domainname }.
+.SH SEE ALSO
+.BR uname (1),
+.BR getdomainname (2),
+.BR gethostname (2),
+.BR uts_namespaces (7)
diff --git a/man/man2/unimplemented.2 b/man/man2/unimplemented.2
new file mode 100644
index 000000000..577380615
--- /dev/null
+++ b/man/man2/unimplemented.2
@@ -0,0 +1,48 @@
+.\" Copyright 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Updated, aeb, 980612
+.\"
+.TH UNIMPLEMENTED 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+afs_syscall, break, fattach, fdetach, ftime, getmsg, getpmsg, gtty, isastream,
+lock, madvise1, mpx, prof, profil, putmsg, putpmsg, security,
+stty, tuxcall, ulimit, vserver \- unimplemented system calls
+.SH SYNOPSIS
+.nf
+Unimplemented system calls.
+.fi
+.SH DESCRIPTION
+These system calls are not implemented in the Linux kernel.
+.SH RETURN VALUE
+These system calls always return \-1 and set
+.I errno
+to
+.BR ENOSYS .
+.SH NOTES
+Note that
+.BR ftime (3),
+.BR profil (3),
+and
+.BR ulimit (3)
+are implemented as library functions.
+.P
+Some system calls, like
+.BR alloc_hugepages (2),
+.BR free_hugepages (2),
+.BR ioperm (2),
+.BR iopl (2),
+and
+.BR vm86 (2)
+exist only on certain architectures.
+.P
+Some system calls, like
+.BR ipc (2),
+.BR create_module (2),
+.BR init_module (2),
+and
+.BR delete_module (2)
+exist only when the Linux kernel was built with support for them.
+.SH SEE ALSO
+.BR syscalls (2)
diff --git a/man/man2/unlink.2 b/man/man2/unlink.2
new file mode 100644
index 000000000..ed729109d
--- /dev/null
+++ b/man/man2/unlink.2
@@ -0,0 +1,298 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Ian Jackson
+.\"             and Copyright (C) 2006, 2014 Michael Kerrisk.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-09-08 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-05-17 by aeb
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH unlink 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+unlink, unlinkat \- delete a name and possibly the file it refers to
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int unlink(const char *" pathname );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of " AT_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int unlinkat(int " dirfd ", const char *" pathname ", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR unlinkat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+.BR unlink ()
+deletes a name from the filesystem.
+If that name was the
+last link to a file and no processes have the file open, the file is
+deleted and the space it was using is made available for reuse.
+.P
+If the name was the last link to a file but any processes still have
+the file open, the file will remain in existence until the last file
+descriptor referring to it is closed.
+.P
+If the name referred to a symbolic link, the link is removed.
+.P
+If the name referred to a socket, FIFO, or device, the name for it is
+removed but processes which have the object open may continue to use
+it.
+.SS unlinkat()
+The
+.BR unlinkat ()
+system call operates in exactly the same way as either
+.BR unlink ()
+or
+.BR rmdir (2)
+(depending on whether or not
+.I flags
+includes the
+.B AT_REMOVEDIR
+flag)
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR unlink ()
+and
+.BR rmdir (2)
+for a relative pathname).
+.P
+If the pathname given in
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR unlink ()
+and
+.BR rmdir (2)).
+.P
+If the pathname given in
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+.I flags
+is a bit mask that can either be specified as 0, or by ORing
+together flag values that control the operation of
+.BR unlinkat ().
+Currently, only one such flag is defined:
+.TP
+.B AT_REMOVEDIR
+By default,
+.BR unlinkat ()
+performs the equivalent of
+.BR unlink ()
+on
+.IR pathname .
+If the
+.B AT_REMOVEDIR
+flag is specified, it
+performs the equivalent of
+.BR rmdir (2)
+on
+.IR pathname .
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR unlinkat ().
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Write access to the directory containing
+.I pathname
+is not allowed for the process's effective UID, or one of the
+directories in
+.I pathname
+did not allow search permission.
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBUSY
+The file
+.I pathname
+cannot be unlinked because it is being used by the system
+or another process;
+for example, it is a mount point
+or the NFS client software created it to represent an
+active but otherwise nameless inode ("NFS silly renamed").
+.TP
+.B EFAULT
+.I pathname
+points outside your accessible address space.
+.TP
+.B EIO
+An I/O error occurred.
+.TP
+.B EISDIR
+.I pathname
+refers to a directory.
+(This is the non-POSIX value returned since Linux 2.1.132.)
+.TP
+.B ELOOP
+Too many symbolic links were encountered in translating
+.IR pathname .
+.TP
+.B ENAMETOOLONG
+.IR pathname " was too long."
+.TP
+.B ENOENT
+A component in
+.I pathname
+does not exist or is a dangling symbolic link, or
+.I pathname
+is empty.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOTDIR
+A component used as a directory in
+.I pathname
+is not, in fact, a directory.
+.TP
+.B EPERM
+The system does not allow unlinking of directories,
+or unlinking of directories requires privileges that the
+calling process doesn't have.
+(This is the POSIX prescribed error return;
+as noted above, Linux returns
+.B EISDIR
+for this case.)
+.TP
+.BR EPERM " (Linux only)"
+The filesystem does not allow unlinking of files.
+.TP
+.BR EPERM " or " EACCES
+The directory containing
+.I pathname
+has the sticky bit
+.RB ( S_ISVTX )
+set and the process's effective UID is neither the UID of the file to
+be deleted nor that of the directory containing it, and
+the process is not privileged (Linux: does not have the
+.B CAP_FOWNER
+capability).
+.TP
+.B EPERM
+The file to be unlinked is marked immutable or append-only.
+(See
+.BR ioctl_iflags (2).)
+.TP
+.B EROFS
+.I pathname
+refers to a file on a read-only filesystem.
+.P
+The same errors that occur for
+.BR unlink ()
+and
+.BR rmdir (2)
+can also occur for
+.BR unlinkat ().
+The following additional errors can occur for
+.BR unlinkat ():
+.TP
+.B EBADF
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EINVAL
+An invalid flag value was specified in
+.IR flags .
+.TP
+.B EISDIR
+.I pathname
+refers to a directory, and
+.B AT_REMOVEDIR
+was not specified in
+.IR flags .
+.TP
+.B ENOTDIR
+.I pathname
+is relative and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR unlink ()
+SVr4, 4.3BSD, POSIX.1-2001.
+.\" SVr4 documents additional error
+.\" conditions EINTR, EMULTIHOP, ETXTBSY, ENOLINK.
+.TP
+.BR unlinkat ()
+POSIX.1-2008.
+Linux 2.6.16,
+glibc 2.4.
+.SS glibc
+On older kernels where
+.BR unlinkat ()
+is unavailable, the glibc wrapper function falls back to the use of
+.BR unlink ()
+or
+.BR rmdir (2).
+When
+.I pathname
+is a relative pathname,
+glibc constructs a pathname based on the symbolic link in
+.I /proc/self/fd
+that corresponds to the
+.I dirfd
+argument.
+.SH BUGS
+Infelicities in the protocol underlying NFS can cause the unexpected
+disappearance of files which are still being used.
+.SH SEE ALSO
+.BR rm (1),
+.BR unlink (1),
+.BR chmod (2),
+.BR link (2),
+.BR mknod (2),
+.BR open (2),
+.BR rename (2),
+.BR rmdir (2),
+.BR mkfifo (3),
+.BR remove (3),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/unlinkat.2 b/man/man2/unlinkat.2
new file mode 100644
index 000000000..4921f7313
--- /dev/null
+++ b/man/man2/unlinkat.2
@@ -0,0 +1 @@
+.so man2/unlink.2
diff --git a/man/man2/unshare.2 b/man/man2/unshare.2
new file mode 100644
index 000000000..98d92cf72
--- /dev/null
+++ b/man/man2/unshare.2
@@ -0,0 +1,572 @@
+.\" Copyright (C) 2006, Janak Desai <janak@us.ibm.com>
+.\" and Copyright (C) 2006, 2012 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Patch Justification:
+.\" unshare system call is needed to implement, using PAM,
+.\" per-security_context and/or per-user namespace to provide
+.\" polyinstantiated directories. Using unshare and bind mounts, a
+.\" PAM module can create private namespace with appropriate
+.\" directories(based on user's security context) bind mounted on
+.\" public directories such as /tmp, thus providing an instance of
+.\" /tmp that is based on user's security context. Without the
+.\" unshare system call, namespace separation can only be achieved
+.\" by clone, which would require porting and maintaining all commands
+.\" such as login, and su, that establish a user session.
+.\"
+.TH unshare 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+unshare \- disassociate parts of the process execution context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #define _GNU_SOURCE
+.B #include <sched.h>
+.P
+.BI "int unshare(int " flags );
+.fi
+.SH DESCRIPTION
+.BR unshare ()
+allows a process (or thread) to disassociate parts of its execution
+context that are currently being shared with other processes (or threads).
+Part of the execution context, such as the mount namespace, is shared
+implicitly when a new process is created using
+.BR fork (2)
+or
+.BR vfork (2),
+while other parts, such as virtual memory, may be
+shared by explicit request when creating a process or thread using
+.BR clone (2).
+.P
+The main use of
+.BR unshare ()
+is to allow a process to control its
+shared execution context without creating a new process.
+.P
+The
+.I flags
+argument is a bit mask that specifies which parts of
+the execution context should be unshared.
+This argument is specified by ORing together zero or more
+of the following constants:
+.TP
+.B CLONE_FILES
+Reverse the effect of the
+.BR clone (2)
+.B CLONE_FILES
+flag.
+Unshare the file descriptor table, so that the calling process
+no longer shares its file descriptors with any other process.
+.TP
+.B CLONE_FS
+Reverse the effect of the
+.BR clone (2)
+.B CLONE_FS
+flag.
+Unshare filesystem attributes, so that the calling process
+no longer shares its root directory
+.RB ( chroot (2)),
+current directory
+.RB ( chdir (2)),
+or umask
+.RB ( umask (2))
+attributes with any other process.
+.TP
+.BR CLONE_NEWCGROUP " (since Linux 4.6)"
+This flag has the same effect as the
+.BR clone (2)
+.B CLONE_NEWCGROUP
+flag.
+Unshare the cgroup namespace.
+Use of
+.B CLONE_NEWCGROUP
+requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR CLONE_NEWIPC " (since Linux 2.6.19)"
+This flag has the same effect as the
+.BR clone (2)
+.B CLONE_NEWIPC
+flag.
+Unshare the IPC namespace,
+so that the calling process has a private copy of the
+IPC namespace which is not shared with any other process.
+Specifying this flag automatically implies
+.B CLONE_SYSVSEM
+as well.
+Use of
+.B CLONE_NEWIPC
+requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR CLONE_NEWNET " (since Linux 2.6.24)"
+This flag has the same effect as the
+.BR clone (2)
+.B CLONE_NEWNET
+flag.
+Unshare the network namespace,
+so that the calling process is moved into a
+new network namespace which is not shared
+with any previously existing process.
+Use of
+.B CLONE_NEWNET
+requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B CLONE_NEWNS
+.\" These flag name are inconsistent:
+.\" CLONE_NEWNS does the same thing in clone(), but CLONE_VM,
+.\" CLONE_FS, and CLONE_FILES reverse the action of the clone()
+.\" flags of the same name.
+This flag has the same effect as the
+.BR clone (2)
+.B CLONE_NEWNS
+flag.
+Unshare the mount namespace,
+so that the calling process has a private copy of
+its namespace which is not shared with any other process.
+Specifying this flag automatically implies
+.B CLONE_FS
+as well.
+Use of
+.B CLONE_NEWNS
+requires the
+.B CAP_SYS_ADMIN
+capability.
+For further information, see
+.BR mount_namespaces (7).
+.TP
+.BR CLONE_NEWPID " (since Linux 3.8)"
+This flag has the same effect as the
+.BR clone (2)
+.B CLONE_NEWPID
+flag.
+Unshare the PID namespace,
+so that the calling process has a new PID namespace for its children
+which is not shared with any previously existing process.
+The calling process is
+.I not
+moved into the new namespace.
+The first child created by the calling process will have
+the process ID 1 and will assume the role of
+.BR init (1)
+in the new namespace.
+.B CLONE_NEWPID
+automatically implies
+.B CLONE_THREAD
+as well.
+Use of
+.B CLONE_NEWPID
+requires the
+.B CAP_SYS_ADMIN
+capability.
+For further information, see
+.BR pid_namespaces (7).
+.TP
+.BR CLONE_NEWTIME " (since Linux 5.6)"
+Unshare the time namespace,
+so that the calling process has a new time namespace for its children
+which is not shared with any previously existing process.
+The calling process is
+.I not
+moved into the new namespace.
+Use of
+.B CLONE_NEWTIME
+requires the
+.B CAP_SYS_ADMIN
+capability.
+For further information, see
+.BR time_namespaces (7).
+.TP
+.BR CLONE_NEWUSER " (since Linux 3.8)"
+This flag has the same effect as the
+.BR clone (2)
+.B CLONE_NEWUSER
+flag.
+Unshare the user namespace,
+so that the calling process is moved into a new user namespace
+which is not shared with any previously existing process.
+As with the child process created by
+.BR clone (2)
+with the
+.B CLONE_NEWUSER
+flag, the caller obtains a full set of capabilities in the new namespace.
+.IP
+.B CLONE_NEWUSER
+requires that the calling process is not threaded; specifying
+.B CLONE_NEWUSER
+automatically implies
+.BR CLONE_THREAD .
+Since Linux 3.9,
+.\" commit e66eded8309ebf679d3d3c1f5820d1f2ca332c71
+.\" https://lwn.net/Articles/543273/
+.B CLONE_NEWUSER
+also automatically implies
+.BR CLONE_FS .
+.B CLONE_NEWUSER
+requires that the user ID and group ID
+of the calling process are mapped to user IDs and group IDs in the
+user namespace of the calling process at the time of the call.
+.IP
+For further information on user namespaces, see
+.BR user_namespaces (7).
+.TP
+.BR CLONE_NEWUTS " (since Linux 2.6.19)"
+This flag has the same effect as the
+.BR clone (2)
+.B CLONE_NEWUTS
+flag.
+Unshare the UTS IPC namespace,
+so that the calling process has a private copy of the
+UTS namespace which is not shared with any other process.
+Use of
+.B CLONE_NEWUTS
+requires the
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR CLONE_SYSVSEM " (since Linux 2.6.26)"
+.\" commit 9edff4ab1f8d82675277a04e359d0ed8bf14a7b7
+This flag reverses the effect of the
+.BR clone (2)
+.B CLONE_SYSVSEM
+flag.
+Unshare System\ V semaphore adjustment
+.RI ( semadj )
+values,
+so that the calling process has a new empty
+.I semadj
+list that is not shared with any other process.
+If this is the last process that has a reference to the process's current
+.I semadj
+list, then the adjustments in that list are applied
+to the corresponding semaphores, as described in
+.BR semop (2).
+.\" CLONE_NEWNS If CLONE_SIGHAND is set and signals are also being shared
+.\" (i.e., current->signal->count > 1), force CLONE_THREAD.
+.P
+In addition,
+.BR CLONE_THREAD ,
+.BR CLONE_SIGHAND ,
+and
+.B CLONE_VM
+can be specified in
+.I flags
+if the caller is single threaded (i.e., it is not sharing
+its address space with another process or thread).
+In this case, these flags have no effect.
+(Note also that specifying
+.B CLONE_THREAD
+automatically implies
+.BR CLONE_VM ,
+and specifying
+.B CLONE_VM
+automatically implies
+.BR CLONE_SIGHAND .)
+.\" As at 3.9, the following forced implications also apply,
+.\" although the relevant flags are not yet implemented.
+.\" If CLONE_THREAD is set force CLONE_VM.
+.\" If CLONE_VM is set, force CLONE_SIGHAND.
+.\"
+If the process is multithreaded, then
+the use of these flags results in an error.
+.\" See kernel/fork.c::check_unshare_flags()
+.P
+If
+.I flags
+is specified as zero, then
+.BR unshare ()
+is a no-op;
+no changes are made to the calling process's execution context.
+.SH RETURN VALUE
+On success, zero returned.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+An invalid bit was specified in
+.IR flags .
+.TP
+.B EINVAL
+.BR CLONE_THREAD ,
+.BR CLONE_SIGHAND ,
+or
+.B CLONE_VM
+was specified in
+.IR flags ,
+and the caller is multithreaded.
+.TP
+.B EINVAL
+.B CLONE_NEWIPC
+was specified in
+.IR flags ,
+but the kernel was not configured with the
+.B CONFIG_SYSVIPC
+and
+.B CONFIG_IPC_NS
+options.
+.TP
+.B EINVAL
+.B CLONE_NEWNET
+was specified in
+.IR flags ,
+but the kernel was not configured with the
+.B CONFIG_NET_NS
+option.
+.TP
+.B EINVAL
+.B CLONE_NEWPID
+was specified in
+.IR flags ,
+but the kernel was not configured with the
+.B CONFIG_PID_NS
+option.
+.TP
+.B EINVAL
+.B CLONE_NEWUSER
+was specified in
+.IR flags ,
+but the kernel was not configured with the
+.B CONFIG_USER_NS
+option.
+.TP
+.B EINVAL
+.B CLONE_NEWUTS
+was specified in
+.IR flags ,
+but the kernel was not configured with the
+.B CONFIG_UTS_NS
+option.
+.TP
+.B EINVAL
+.B CLONE_NEWPID
+was specified in
+.IR flags ,
+but the process has previously called
+.BR unshare ()
+with the
+.B CLONE_NEWPID
+flag.
+.TP
+.B ENOMEM
+Cannot allocate sufficient memory to copy parts of caller's
+context that need to be unshared.
+.TP
+.BR ENOSPC " (since Linux 3.7)"
+.\" commit f2302505775fd13ba93f034206f1e2a587017929
+.B CLONE_NEWPID
+was specified in flags,
+but the limit on the nesting depth of PID namespaces
+would have been exceeded; see
+.BR pid_namespaces (7).
+.TP
+.BR ENOSPC " (since Linux 4.9; beforehand " EUSERS )
+.B CLONE_NEWUSER
+was specified in
+.IR flags ,
+and the call would cause the limit on the number of
+nested user namespaces to be exceeded.
+See
+.BR user_namespaces (7).
+.IP
+From Linux 3.11 to Linux 4.8, the error diagnosed in this case was
+.BR EUSERS .
+.TP
+.BR ENOSPC " (since Linux 4.9)"
+One of the values in
+.I flags
+specified the creation of a new user namespace,
+but doing so would have caused the limit defined by the corresponding file in
+.I /proc/sys/user
+to be exceeded.
+For further details, see
+.BR namespaces (7).
+.TP
+.B EPERM
+The calling process did not have the required privileges for this operation.
+.TP
+.B EPERM
+.B CLONE_NEWUSER
+was specified in
+.IR flags ,
+but either the effective user ID or the effective group ID of the caller
+does not have a mapping in the parent namespace (see
+.BR user_namespaces (7)).
+.TP
+.BR EPERM " (since Linux 3.9)"
+.\" commit 3151527ee007b73a0ebd296010f1c0454a919c7d
+.B CLONE_NEWUSER
+was specified in
+.I flags
+and the caller is in a chroot environment
+.\" FIXME What is the rationale for this restriction?
+(i.e., the caller's root directory does not match the root directory
+of the mount namespace in which it resides).
+.TP
+.BR EUSERS " (from Linux 3.11 to Linux 4.8)"
+.B CLONE_NEWUSER
+was specified in
+.IR flags ,
+and the limit on the number of nested user namespaces would be exceeded.
+See the discussion of the
+.B ENOSPC
+error above.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.16.
+.SH NOTES
+Not all of the process attributes that can be shared when
+a new process is created using
+.BR clone (2)
+can be unshared using
+.BR unshare ().
+In particular, as at kernel 3.8,
+.\" FIXME all of the following needs to be reviewed for the current kernel
+.BR unshare ()
+does not implement flags that reverse the effects of
+.BR CLONE_SIGHAND ,
+.\" However, we can do unshare(CLONE_SIGHAND) if CLONE_SIGHAND
+.\" was not specified when doing clone(); i.e., unsharing
+.\" signal handlers is permitted if we are not actually
+.\" sharing signal handlers.   mtk
+.BR CLONE_THREAD ,
+or
+.BR CLONE_VM .
+.\" However, we can do unshare(CLONE_VM) if CLONE_VM
+.\" was not specified when doing clone(); i.e., unsharing
+.\" virtual memory is permitted if we are not actually
+.\" sharing virtual memory.   mtk
+Such functionality may be added in the future, if required.
+.\"
+.\"9) Future Work
+.\"--------------
+.\"The current implementation of unshare does not allow unsharing of
+.\"signals and signal handlers. Signals are complex to begin with and
+.\"to unshare signals and/or signal handlers of a currently running
+.\"process is even more complex. If in the future there is a specific
+.\"need to allow unsharing of signals and/or signal handlers, it can
+.\"be incrementally added to unshare without affecting legacy
+.\"applications using unshare.
+.\"
+.P
+Creating all kinds of namespace, except user namespaces, requires the
+.B CAP_SYS_ADMIN
+capability.
+However, since creating a user namespace automatically confers a full set of
+capabilities,
+creating both a user namespace and any other type of namespace in the same
+.BR unshare ()
+call does not require the
+.B CAP_SYS_ADMIN
+capability in the original namespace.
+.SH EXAMPLES
+The program below provides a simple implementation of the
+.BR unshare (1)
+command, which unshares one or more namespaces and executes the
+command supplied in its command-line arguments.
+Here's an example of the use of this program,
+running a shell in a new mount namespace,
+and verifying that the original shell and the
+new shell are in separate mount namespaces:
+.P
+.in +4n
+.EX
+$ \fBreadlink /proc/$$/ns/mnt\fP
+mnt:[4026531840]
+$ \fBsudo ./unshare \-m /bin/bash\fP
+# \fBreadlink /proc/$$/ns/mnt\fP
+mnt:[4026532325]
+.EE
+.in
+.P
+The differing output of the two
+.BR readlink (1)
+commands shows that the two shells are in different mount namespaces.
+.SS Program source
+\&
+.\" SRC BEGIN (unshare.c)
+.EX
+/* unshare.c
+\&
+   A simple implementation of the unshare(1) command: unshare
+   namespaces and execute a command.
+*/
+#define _GNU_SOURCE
+#include <err.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+static void
+usage(char *pname)
+{
+    fprintf(stderr, "Usage: %s [options] program [arg...]\en", pname);
+    fprintf(stderr, "Options can be:\en");
+    fprintf(stderr, "    \-C   unshare cgroup namespace\en");
+    fprintf(stderr, "    \-i   unshare IPC namespace\en");
+    fprintf(stderr, "    \-m   unshare mount namespace\en");
+    fprintf(stderr, "    \-n   unshare network namespace\en");
+    fprintf(stderr, "    \-p   unshare PID namespace\en");
+    fprintf(stderr, "    \-t   unshare time namespace\en");
+    fprintf(stderr, "    \-u   unshare UTS namespace\en");
+    fprintf(stderr, "    \-U   unshare user namespace\en");
+    exit(EXIT_FAILURE);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int flags, opt;
+\&
+    flags = 0;
+\&
+    while ((opt = getopt(argc, argv, "CimnptuU")) != \-1) {
+        switch (opt) {
+        case \[aq]C\[aq]: flags |= CLONE_NEWCGROUP;     break;
+        case \[aq]i\[aq]: flags |= CLONE_NEWIPC;        break;
+        case \[aq]m\[aq]: flags |= CLONE_NEWNS;         break;
+        case \[aq]n\[aq]: flags |= CLONE_NEWNET;        break;
+        case \[aq]p\[aq]: flags |= CLONE_NEWPID;        break;
+        case \[aq]t\[aq]: flags |= CLONE_NEWTIME;       break;
+        case \[aq]u\[aq]: flags |= CLONE_NEWUTS;        break;
+        case \[aq]U\[aq]: flags |= CLONE_NEWUSER;       break;
+        default:  usage(argv[0]);
+        }
+    }
+\&
+    if (optind >= argc)
+        usage(argv[0]);
+\&
+    if (unshare(flags) == \-1)
+        err(EXIT_FAILURE, "unshare");
+\&
+    execvp(argv[optind], &argv[optind]);
+    err(EXIT_FAILURE, "execvp");
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR unshare (1),
+.BR clone (2),
+.BR fork (2),
+.BR kcmp (2),
+.BR setns (2),
+.BR vfork (2),
+.BR namespaces (7)
+.P
+.I Documentation/userspace\-api/unshare.rst
+in the Linux kernel source tree
+.\" commit f504d47be5e8fa7ecf2bf660b18b42e6960c0eb2
+(or
+.I Documentation/unshare.txt
+before Linux 4.12)
diff --git a/man/man2/uselib.2 b/man/man2/uselib.2
new file mode 100644
index 000000000..bb567c688
--- /dev/null
+++ b/man/man2/uselib.2
@@ -0,0 +1,106 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2005-01-09 by aeb
+.\"
+.TH uselib 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+uselib \- load shared library
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "[[deprecated]] int uselib(const char *" library );
+.fi
+.SH DESCRIPTION
+The system call
+.BR uselib ()
+serves to load
+a shared library to be used by the calling process.
+It is given a pathname.
+The address where to load is found
+in the library itself.
+The library can have any recognized
+binary format.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+In addition to all of the error codes returned by
+.BR open (2)
+and
+.BR mmap (2),
+the following may also be returned:
+.TP
+.B EACCES
+The library specified by
+.I library
+does not have read or execute permission, or the caller does not have
+search permission for one of the directories in the path prefix.
+(See also
+.BR path_resolution (7).)
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOEXEC
+The file specified by
+.I library
+is not an executable of a known type;
+for example, it does not have the correct magic numbers.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+This obsolete system call is not supported by glibc.
+No declaration is provided in glibc headers, but, through a quirk of history,
+glibc before glibc 2.23 did export an ABI for this system call.
+Therefore, in order to employ this system call,
+it was sufficient to manually declare the interface in your code;
+alternatively, you could invoke the system call using
+.BR syscall (2).
+.P
+In ancient libc versions (before glibc 2.0),
+.BR uselib ()
+was used to load
+the shared libraries with names found in an array of names
+in the binary.
+.\" .P
+.\" .\" libc 4.3.1f - changelog 1993-03-02
+.\" Since libc 4.3.2, startup code tries to prefix these names
+.\" with "/usr/lib", "/lib" and "" before giving up.
+.\" .\" libc 4.3.4 - changelog 1993-04-21
+.\" In libc 4.3.4 and later these names are looked for in the directories
+.\" found in
+.\" .BR LD_LIBRARY_PATH ,
+.\" and if not found there,
+.\" prefixes "/usr/lib", "/lib" and "/" are tried.
+.\" .P
+.\" From libc 4.4.4 on only the library "/lib/ld.so" is loaded,
+.\" so that this dynamic library can load the remaining libraries needed
+.\" (again using this call).
+.\" This is also the state of affairs in libc5.
+.\" .P
+.\" glibc2 does not use this call.
+.P
+Since Linux 3.15,
+.\" commit 69369a7003735d0d8ef22097e27a55a8bad9557a
+this system call is available only when the kernel is configured with the
+.B CONFIG_USELIB
+option.
+.SH SEE ALSO
+.BR ar (1),
+.BR gcc (1),
+.BR ld (1),
+.BR ldd (1),
+.BR mmap (2),
+.BR open (2),
+.BR dlopen (3),
+.BR capabilities (7),
+.BR ld.so (8)
diff --git a/man/man2/userfaultfd.2 b/man/man2/userfaultfd.2
new file mode 100644
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+.\" Copyright (c) 2016, IBM Corporation.
+.\" Written by Mike Rapoport <rppt@linux.vnet.ibm.com>
+.\" and Copyright (C) 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH userfaultfd 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+userfaultfd \- create a file descriptor for handling page faults in user space
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" "             /* Definition of " O_* " constants */"
+.BR "#include <sys/syscall.h>" "       /* Definition of " SYS_* " constants */"
+.BR "#include <linux/userfaultfd.h>" " /* Definition of " UFFD_* " constants */"
+.B #include <unistd.h>
+.P
+.BI "int syscall(SYS_userfaultfd, int " flags );
+.fi
+.P
+.IR Note :
+glibc provides no wrapper for
+.BR userfaultfd (),
+necessitating the use of
+.BR syscall (2).
+.SH DESCRIPTION
+.BR userfaultfd ()
+creates a new userfaultfd object that can be used for delegation of page-fault
+handling to a user-space application,
+and returns a file descriptor that refers to the new object.
+The new userfaultfd object is configured using
+.BR ioctl (2).
+.P
+Once the userfaultfd object is configured, the application can use
+.BR read (2)
+to receive userfaultfd notifications.
+The reads from userfaultfd may be blocking or non-blocking,
+depending on the value of
+.I flags
+used for the creation of the userfaultfd or subsequent calls to
+.BR fcntl (2).
+.P
+The following values may be bitwise ORed in
+.I flags
+to change the behavior of
+.BR userfaultfd ():
+.TP
+.B O_CLOEXEC
+Enable the close-on-exec flag for the new userfaultfd file descriptor.
+See the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2).
+.TP
+.B O_NONBLOCK
+Enables non-blocking operation for the userfaultfd object.
+See the description of the
+.B O_NONBLOCK
+flag in
+.BR open (2).
+.TP
+.B UFFD_USER_MODE_ONLY
+This is an userfaultfd-specific flag that was introduced in Linux 5.11.
+When set, the userfaultfd object will only be able to handle
+page faults originated from the user space on the registered regions.
+When a kernel-originated fault was triggered
+on the registered range with this userfaultfd, a
+.B SIGBUS
+signal will be delivered.
+.P
+When the last file descriptor referring to a userfaultfd object is closed,
+all memory ranges that were registered with the object are unregistered
+and unread events are flushed.
+.\"
+.P
+Userfaultfd supports three modes of registration:
+.TP
+.BR UFFDIO_REGISTER_MODE_MISSING " (since Linux 4.10)"
+When registered with
+.B UFFDIO_REGISTER_MODE_MISSING
+mode, user-space will receive a page-fault notification
+when a missing page is accessed.
+The faulted thread will be stopped from execution until the page fault is
+resolved from user-space by either an
+.B UFFDIO_COPY
+or an
+.B UFFDIO_ZEROPAGE
+ioctl.
+.TP
+.BR UFFDIO_REGISTER_MODE_MINOR " (since Linux 5.13)"
+When registered with
+.B UFFDIO_REGISTER_MODE_MINOR
+mode, user-space will receive a page-fault notification
+when a minor page fault occurs.
+That is,
+when a backing page is in the page cache,
+but page table entries don't yet exist.
+The faulted thread will be stopped from execution
+until the page fault is resolved from user-space by an
+.B UFFDIO_CONTINUE
+ioctl.
+.TP
+.BR UFFDIO_REGISTER_MODE_WP " (since Linux 5.7)"
+When registered with
+.B UFFDIO_REGISTER_MODE_WP
+mode, user-space will receive a page-fault notification
+when a write-protected page is written.
+The faulted thread will be stopped from execution
+until user-space write-unprotects the page using an
+.B UFFDIO_WRITEPROTECT
+ioctl.
+.P
+Multiple modes can be enabled at the same time for the same memory range.
+.P
+Since Linux 4.14, a userfaultfd page-fault notification can selectively embed
+faulting thread ID information into the notification.
+One needs to enable this feature explicitly using the
+.B UFFD_FEATURE_THREAD_ID
+feature bit when initializing the userfaultfd context.
+By default, thread ID reporting is disabled.
+.SS Usage
+The userfaultfd mechanism is designed to allow a thread in a multithreaded
+program to perform user-space paging for the other threads in the process.
+When a page fault occurs for one of the regions registered
+to the userfaultfd object,
+the faulting thread is put to sleep and
+an event is generated that can be read via the userfaultfd file descriptor.
+The fault-handling thread reads events from this file descriptor and services
+them using the operations described in
+.BR ioctl_userfaultfd (2).
+When servicing the page fault events,
+the fault-handling thread can trigger a wake-up for the sleeping thread.
+.P
+It is possible for the faulting threads and the fault-handling threads
+to run in the context of different processes.
+In this case, these threads may belong to different programs,
+and the program that executes the faulting threads
+will not necessarily cooperate with the program that handles the page faults.
+In such non-cooperative mode,
+the process that monitors userfaultfd and handles page faults
+needs to be aware of the changes in the virtual memory layout
+of the faulting process to avoid memory corruption.
+.P
+Since Linux 4.11,
+userfaultfd can also notify the fault-handling threads about changes
+in the virtual memory layout of the faulting process.
+In addition, if the faulting process invokes
+.BR fork (2),
+the userfaultfd objects associated with the parent may be duplicated
+into the child process and the userfaultfd monitor will be notified
+(via the
+.B UFFD_EVENT_FORK
+described below)
+about the file descriptor associated with the userfault objects
+created for the child process,
+which allows the userfaultfd monitor to perform user-space paging
+for the child process.
+Unlike page faults which have to be synchronous and require an
+explicit or implicit wakeup,
+all other events are delivered asynchronously and
+the non-cooperative process resumes execution as
+soon as the userfaultfd manager executes
+.BR read (2).
+The userfaultfd manager should carefully synchronize calls to
+.B UFFDIO_COPY
+with the processing of events.
+.P
+The current asynchronous model of the event delivery is optimal for
+single threaded non-cooperative userfaultfd manager implementations.
+.\" Regarding the preceding sentence, Mike Rapoport says:
+.\"     The major point here is that current events delivery model could be
+.\"     problematic for multi-threaded monitor. I even suspect that it would be
+.\"     impossible to ensure synchronization between page faults and non-page
+.\"     fault events in multi-threaded monitor.
+.\" .P
+.\" FIXME elaborate about non-cooperating mode, describe its limitations
+.\" for kernels before Linux 4.11, features added in Linux 4.11
+.\" and limitations remaining in Linux 4.11
+.\" Maybe it's worth adding a dedicated sub-section...
+.\"
+.P
+Since Linux 5.7, userfaultfd is able to do
+synchronous page dirty tracking using the new write-protect register mode.
+One should check against the feature bit
+.B UFFD_FEATURE_PAGEFAULT_FLAG_WP
+before using this feature.
+Similar to the original userfaultfd missing mode, the write-protect mode will
+generate a userfaultfd notification when the protected page is written.
+The user needs to resolve the page fault by unprotecting the faulted page and
+kicking the faulted thread to continue.
+For more information,
+please refer to the "Userfaultfd write-protect mode" section.
+.\"
+.SS Userfaultfd operation
+After the userfaultfd object is created with
+.BR userfaultfd (),
+the application must enable it using the
+.B UFFDIO_API
+.BR ioctl (2)
+operation.
+This operation allows a two-step handshake between the kernel and user space
+to determine what API version and features the kernel supports,
+and then to enable those features user space wants.
+This operation must be performed before any of the other
+.BR ioctl (2)
+operations described below (or those operations fail with the
+.B EINVAL
+error).
+.P
+After a successful
+.B UFFDIO_API
+operation,
+the application then registers memory address ranges using the
+.B UFFDIO_REGISTER
+.BR ioctl (2)
+operation.
+After successful completion of a
+.B UFFDIO_REGISTER
+operation,
+a page fault occurring in the requested memory range, and satisfying
+the mode defined at the registration time, will be forwarded by the kernel to
+the user-space application.
+The application can then use various (e.g.,
+.BR UFFDIO_COPY ,
+.BR UFFDIO_ZEROPAGE ,
+or
+.BR UFFDIO_CONTINUE )
+.BR ioctl (2)
+operations to resolve the page fault.
+.P
+Since Linux 4.14, if the application sets the
+.B UFFD_FEATURE_SIGBUS
+feature bit using the
+.B UFFDIO_API
+.BR ioctl (2),
+no page-fault notification will be forwarded to user space.
+Instead a
+.B SIGBUS
+signal is delivered to the faulting process.
+With this feature,
+userfaultfd can be used for robustness purposes to simply catch
+any access to areas within the registered address range that do not
+have pages allocated, without having to listen to userfaultfd events.
+No userfaultfd monitor will be required for dealing with such memory
+accesses.
+For example, this feature can be useful for applications that
+want to prevent the kernel from automatically allocating pages and filling
+holes in sparse files when the hole is accessed through a memory mapping.
+.P
+The
+.B UFFD_FEATURE_SIGBUS
+feature is implicitly inherited through
+.BR fork (2)
+if used in combination with
+.BR UFFD_FEATURE_FORK .
+.P
+Details of the various
+.BR ioctl (2)
+operations can be found in
+.BR ioctl_userfaultfd (2).
+.P
+Since Linux 4.11, events other than page-fault may enabled during
+.B UFFDIO_API
+operation.
+.P
+Up to Linux 4.11,
+userfaultfd can be used only with anonymous private memory mappings.
+Since Linux 4.11,
+userfaultfd can be also used with hugetlbfs and shared memory mappings.
+.\"
+.SS Userfaultfd write-protect mode (since Linux 5.7)
+Since Linux 5.7, userfaultfd supports write-protect mode for anonymous memory.
+The user needs to first check availability of this feature using
+.B UFFDIO_API
+ioctl against the feature bit
+.B UFFD_FEATURE_PAGEFAULT_FLAG_WP
+before using this feature.
+.P
+Since Linux 5.19,
+the write-protection mode was also supported on
+shmem and hugetlbfs memory types.
+It can be detected with the feature bit
+.BR UFFD_FEATURE_WP_HUGETLBFS_SHMEM .
+.P
+To register with userfaultfd write-protect mode, the user needs to initiate the
+.B UFFDIO_REGISTER
+ioctl with mode
+.B UFFDIO_REGISTER_MODE_WP
+set.
+Note that it is legal to monitor the same memory range with multiple modes.
+For example, the user can do
+.B UFFDIO_REGISTER
+with the mode set to
+.BR "UFFDIO_REGISTER_MODE_MISSING | UFFDIO_REGISTER_MODE_WP" .
+When there is only
+.B UFFDIO_REGISTER_MODE_WP
+registered, user-space will
+.I not
+receive any notification when a missing page is written.
+Instead, user-space will receive a write-protect page-fault notification
+only when an existing but write-protected page got written.
+.P
+After the
+.B UFFDIO_REGISTER
+ioctl completed with
+.B UFFDIO_REGISTER_MODE_WP
+mode set,
+the user can write-protect any existing memory within the range using the ioctl
+.B UFFDIO_WRITEPROTECT
+where
+.I uffdio_writeprotect.mode
+should be set to
+.BR UFFDIO_WRITEPROTECT_MODE_WP .
+.P
+When a write-protect event happens,
+user-space will receive a page-fault notification whose
+.I uffd_msg.pagefault.flags
+will be with
+.B UFFD_PAGEFAULT_FLAG_WP
+flag set.
+Note: since only writes can trigger this kind of fault,
+write-protect notifications will always have the
+.B UFFD_PAGEFAULT_FLAG_WRITE
+bit set along with the
+.B UFFD_PAGEFAULT_FLAG_WP
+bit.
+.P
+To resolve a write-protection page fault, the user should initiate another
+.B UFFDIO_WRITEPROTECT
+ioctl, whose
+.I uffd_msg.pagefault.flags
+should have the flag
+.B UFFDIO_WRITEPROTECT_MODE_WP
+cleared upon the faulted page or range.
+.\"
+.SS Userfaultfd minor fault mode (since Linux 5.13)
+Since Linux 5.13,
+userfaultfd supports minor fault mode.
+In this mode,
+fault messages are produced not for major faults
+(where the page was missing),
+but rather for minor faults,
+where a page exists in the page cache,
+but the page table entries are not yet present.
+The user needs to first check availability of this feature using the
+.B UFFDIO_API
+ioctl with the appropriate feature bits set before using this feature:
+.B UFFD_FEATURE_MINOR_HUGETLBFS
+since Linux 5.13,
+or
+.B UFFD_FEATURE_MINOR_SHMEM
+since Linux 5.14.
+.P
+To register with userfaultfd minor fault mode,
+the user needs to initiate the
+.B UFFDIO_REGISTER
+ioctl with mode
+.B UFFD_REGISTER_MODE_MINOR
+set.
+.P
+When a minor fault occurs,
+user-space will receive a page-fault notification
+whose
+.I uffd_msg.pagefault.flags
+will have the
+.B UFFD_PAGEFAULT_FLAG_MINOR
+flag set.
+.P
+To resolve a minor page fault,
+the handler should decide whether or not
+the existing page contents need to be modified first.
+If so,
+this should be done in-place via a second,
+non-userfaultfd-registered mapping
+to the same backing page
+(e.g., by mapping the shmem or hugetlbfs file twice).
+Once the page is considered "up to date",
+the fault can be resolved by initiating an
+.B UFFDIO_CONTINUE
+ioctl,
+which installs the page table entries and
+(by default)
+wakes up the faulting thread(s).
+.P
+Minor fault mode supports only hugetlbfs-backed (since Linux 5.13)
+and shmem-backed (since Linux 5.14) memory.
+.\"
+.SS Reading from the userfaultfd structure
+Each
+.BR read (2)
+from the userfaultfd file descriptor returns one or more
+.I uffd_msg
+structures, each of which describes a page-fault event
+or an event required for the non-cooperative userfaultfd usage:
+.P
+.in +4n
+.EX
+struct uffd_msg {
+    __u8  event;            /* Type of event */
+    ...
+    union {
+        struct {
+            __u64 flags;    /* Flags describing fault */
+            __u64 address;  /* Faulting address */
+            union {
+                __u32 ptid; /* Thread ID of the fault */
+            } feat;
+        } pagefault;
+\&
+        struct {            /* Since Linux 4.11 */
+            __u32 ufd;      /* Userfault file descriptor
+                               of the child process */
+        } fork;
+\&
+        struct {            /* Since Linux 4.11 */
+            __u64 from;     /* Old address of remapped area */
+            __u64 to;       /* New address of remapped area */
+            __u64 len;      /* Original mapping length */
+        } remap;
+\&
+        struct {            /* Since Linux 4.11 */
+            __u64 start;    /* Start address of removed area */
+            __u64 end;      /* End address of removed area */
+        } remove;
+        ...
+    } arg;
+\&
+    /* Padding fields omitted */
+} __packed;
+.EE
+.in
+.P
+If multiple events are available and the supplied buffer is large enough,
+.BR read (2)
+returns as many events as will fit in the supplied buffer.
+If the buffer supplied to
+.BR read (2)
+is smaller than the size of the
+.I uffd_msg
+structure, the
+.BR read (2)
+fails with the error
+.BR EINVAL .
+.P
+The fields set in the
+.I uffd_msg
+structure are as follows:
+.TP
+.I event
+The type of event.
+Depending of the event type,
+different fields of the
+.I arg
+union represent details required for the event processing.
+The non-page-fault events are generated only when appropriate feature
+is enabled during API handshake with
+.B UFFDIO_API
+.BR ioctl (2).
+.IP
+The following values can appear in the
+.I event
+field:
+.RS
+.TP
+.BR UFFD_EVENT_PAGEFAULT " (since Linux 4.3)"
+A page-fault event.
+The page-fault details are available in the
+.I pagefault
+field.
+.TP
+.BR UFFD_EVENT_FORK " (since Linux 4.11)"
+Generated when the faulting process invokes
+.BR fork (2)
+(or
+.BR clone (2)
+without the
+.B CLONE_VM
+flag).
+The event details are available in the
+.I fork
+field.
+.\" FIXME describe duplication of userfault file descriptor during fork
+.TP
+.BR UFFD_EVENT_REMAP " (since Linux 4.11)"
+Generated when the faulting process invokes
+.BR mremap (2).
+The event details are available in the
+.I remap
+field.
+.TP
+.BR UFFD_EVENT_REMOVE " (since Linux 4.11)"
+Generated when the faulting process invokes
+.BR madvise (2)
+with
+.B MADV_DONTNEED
+or
+.B MADV_REMOVE
+advice.
+The event details are available in the
+.I remove
+field.
+.TP
+.BR UFFD_EVENT_UNMAP " (since Linux 4.11)"
+Generated when the faulting process unmaps a memory range,
+either explicitly using
+.BR munmap (2)
+or implicitly during
+.BR mmap (2)
+or
+.BR mremap (2).
+The event details are available in the
+.I remove
+field.
+.RE
+.TP
+.I pagefault.address
+The address that triggered the page fault.
+.TP
+.I pagefault.flags
+A bit mask of flags that describe the event.
+For
+.BR UFFD_EVENT_PAGEFAULT ,
+the following flag may appear:
+.RS
+.TP
+.B UFFD_PAGEFAULT_FLAG_WP
+If this flag is set, then the fault was a write-protect fault.
+.TP
+.B UFFD_PAGEFAULT_FLAG_MINOR
+If this flag is set, then the fault was a minor fault.
+.TP
+.B UFFD_PAGEFAULT_FLAG_WRITE
+If this flag is set, then the fault was a write fault.
+.P
+If neither
+.B UFFD_PAGEFAULT_FLAG_WP
+nor
+.B UFFD_PAGEFAULT_FLAG_MINOR
+are set, then the fault was a missing fault.
+.RE
+.TP
+.I pagefault.feat.pid
+The thread ID that triggered the page fault.
+.TP
+.I fork.ufd
+The file descriptor associated with the userfault object
+created for the child created by
+.BR fork (2).
+.TP
+.I remap.from
+The original address of the memory range that was remapped using
+.BR mremap (2).
+.TP
+.I remap.to
+The new address of the memory range that was remapped using
+.BR mremap (2).
+.TP
+.I remap.len
+The original length of the memory range that was remapped using
+.BR mremap (2).
+.TP
+.I remove.start
+The start address of the memory range that was freed using
+.BR madvise (2)
+or unmapped
+.TP
+.I remove.end
+The end address of the memory range that was freed using
+.BR madvise (2)
+or unmapped
+.P
+A
+.BR read (2)
+on a userfaultfd file descriptor can fail with the following errors:
+.TP
+.B EINVAL
+The userfaultfd object has not yet been enabled using the
+.B UFFDIO_API
+.BR ioctl (2)
+operation
+.P
+If the
+.B O_NONBLOCK
+flag is enabled in the associated open file description,
+the userfaultfd file descriptor can be monitored with
+.BR poll (2),
+.BR select (2),
+and
+.BR epoll (7).
+When events are available, the file descriptor indicates as readable.
+If the
+.B O_NONBLOCK
+flag is not enabled, then
+.BR poll (2)
+(always) indicates the file as having a
+.B POLLERR
+condition, and
+.BR select (2)
+indicates the file descriptor as both readable and writable.
+.\" FIXME What is the reason for this seemingly odd behavior with respect
+.\" to the O_NONBLOCK flag? (see userfaultfd_poll() in fs/userfaultfd.c).
+.\" Something needs to be said about this.
+.SH RETURN VALUE
+On success,
+.BR userfaultfd ()
+returns a new file descriptor that refers to the userfaultfd object.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+An unsupported value was specified in
+.IR flags .
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been
+reached
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been
+reached.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.BR EPERM " (since Linux 5.2)"
+.\" cefdca0a86be517bc390fc4541e3674b8e7803b0
+The caller is not privileged (does not have the
+.B CAP_SYS_PTRACE
+capability in the initial user namespace), and
+.I /proc/sys/vm/unprivileged_userfaultfd
+has the value 0.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 4.3.
+.P
+Support for hugetlbfs and shared memory areas and
+non-page-fault events was added in Linux 4.11
+.SH NOTES
+The userfaultfd mechanism can be used as an alternative to
+traditional user-space paging techniques based on the use of the
+.B SIGSEGV
+signal and
+.BR mmap (2).
+It can also be used to implement lazy restore
+for checkpoint/restore mechanisms,
+as well as post-copy migration to allow (nearly) uninterrupted execution
+when transferring virtual machines and Linux containers
+from one host to another.
+.SH BUGS
+If the
+.B UFFD_FEATURE_EVENT_FORK
+is enabled and a system call from the
+.BR fork (2)
+family is interrupted by a signal or failed, a stale userfaultfd descriptor
+might be created.
+In this case, a spurious
+.B UFFD_EVENT_FORK
+will be delivered to the userfaultfd monitor.
+.SH EXAMPLES
+The program below demonstrates the use of the userfaultfd mechanism.
+The program creates two threads, one of which acts as the
+page-fault handler for the process, for the pages in a demand-page zero
+region created using
+.BR mmap (2).
+.P
+The program takes one command-line argument,
+which is the number of pages that will be created in a mapping
+whose page faults will be handled via userfaultfd.
+After creating a userfaultfd object,
+the program then creates an anonymous private mapping of the specified size
+and registers the address range of that mapping using the
+.B UFFDIO_REGISTER
+.BR ioctl (2)
+operation.
+The program then creates a second thread that will perform the
+task of handling page faults.
+.P
+The main thread then walks through the pages of the mapping fetching
+bytes from successive pages.
+Because the pages have not yet been accessed,
+the first access of a byte in each page will trigger a page-fault event
+on the userfaultfd file descriptor.
+.P
+Each of the page-fault events is handled by the second thread,
+which sits in a loop processing input from the userfaultfd file descriptor.
+In each loop iteration, the second thread first calls
+.BR poll (2)
+to check the state of the file descriptor,
+and then reads an event from the file descriptor.
+All such events should be
+.B UFFD_EVENT_PAGEFAULT
+events,
+which the thread handles by copying a page of data into
+the faulting region using the
+.B UFFDIO_COPY
+.BR ioctl (2)
+operation.
+.P
+The following is an example of what we see when running the program:
+.P
+.in +4n
+.EX
+$ \fB./userfaultfd_demo 3\fP
+Address returned by mmap() = 0x7fd30106c000
+\&
+fault_handler_thread():
+    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0
+    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106c00f
+        (uffdio_copy.copy returned 4096)
+Read address 0x7fd30106c00f in main(): A
+Read address 0x7fd30106c40f in main(): A
+Read address 0x7fd30106c80f in main(): A
+Read address 0x7fd30106cc0f in main(): A
+\&
+fault_handler_thread():
+    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0
+    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106d00f
+        (uffdio_copy.copy returned 4096)
+Read address 0x7fd30106d00f in main(): B
+Read address 0x7fd30106d40f in main(): B
+Read address 0x7fd30106d80f in main(): B
+Read address 0x7fd30106dc0f in main(): B
+\&
+fault_handler_thread():
+    poll() returns: nready = 1; POLLIN = 1; POLLERR = 0
+    UFFD_EVENT_PAGEFAULT event: flags = 0; address = 7fd30106e00f
+        (uffdio_copy.copy returned 4096)
+Read address 0x7fd30106e00f in main(): C
+Read address 0x7fd30106e40f in main(): C
+Read address 0x7fd30106e80f in main(): C
+Read address 0x7fd30106ec0f in main(): C
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (userfaultfd.c)
+.EX
+/* userfaultfd_demo.c
+\&
+   Licensed under the GNU General Public License version 2 or later.
+*/
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <linux/userfaultfd.h>
+#include <poll.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+\&
+static int page_size;
+\&
+static void *
+fault_handler_thread(void *arg)
+{
+    int                 nready;
+    long                uffd;   /* userfaultfd file descriptor */
+    ssize_t             nread;
+    struct pollfd       pollfd;
+    struct uffdio_copy  uffdio_copy;
+\&
+    static int      fault_cnt = 0; /* Number of faults so far handled */
+    static char     *page = NULL;
+    static struct uffd_msg  msg;  /* Data read from userfaultfd */
+\&
+    uffd = (long) arg;
+\&
+    /* Create a page that will be copied into the faulting region. */
+\&
+    if (page == NULL) {
+        page = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+                    MAP_PRIVATE | MAP_ANONYMOUS, \-1, 0);
+        if (page == MAP_FAILED)
+            err(EXIT_FAILURE, "mmap");
+    }
+\&
+    /* Loop, handling incoming events on the userfaultfd
+       file descriptor. */
+\&
+    for (;;) {
+\&
+        /* See what poll() tells us about the userfaultfd. */
+\&
+        pollfd.fd = uffd;
+        pollfd.events = POLLIN;
+        nready = poll(&pollfd, 1, \-1);
+        if (nready == \-1)
+            err(EXIT_FAILURE, "poll");
+\&
+        printf("\enfault_handler_thread():\en");
+        printf("    poll() returns: nready = %d; "
+               "POLLIN = %d; POLLERR = %d\en", nready,
+               (pollfd.revents & POLLIN) != 0,
+               (pollfd.revents & POLLERR) != 0);
+\&
+        /* Read an event from the userfaultfd. */
+\&
+        nread = read(uffd, &msg, sizeof(msg));
+        if (nread == 0) {
+            printf("EOF on userfaultfd!\en");
+            exit(EXIT_FAILURE);
+        }
+\&
+        if (nread == \-1)
+            err(EXIT_FAILURE, "read");
+\&
+        /* We expect only one kind of event; verify that assumption. */
+\&
+        if (msg.event != UFFD_EVENT_PAGEFAULT) {
+            fprintf(stderr, "Unexpected event on userfaultfd\en");
+            exit(EXIT_FAILURE);
+        }
+\&
+        /* Display info about the page\-fault event. */
+\&
+        printf("    UFFD_EVENT_PAGEFAULT event: ");
+        printf("flags = %"PRIx64"; ", msg.arg.pagefault.flags);
+        printf("address = %"PRIx64"\en", msg.arg.pagefault.address);
+\&
+        /* Copy the page pointed to by \[aq]page\[aq] into the faulting
+           region. Vary the contents that are copied in, so that it
+           is more obvious that each fault is handled separately. */
+\&
+        memset(page, \[aq]A\[aq] + fault_cnt % 20, page_size);
+        fault_cnt++;
+\&
+        uffdio_copy.src = (unsigned long) page;
+\&
+        /* We need to handle page faults in units of pages(!).
+           So, round faulting address down to page boundary. */
+\&
+        uffdio_copy.dst = (unsigned long) msg.arg.pagefault.address &
+                                           \[ti](page_size \- 1);
+        uffdio_copy.len = page_size;
+        uffdio_copy.mode = 0;
+        uffdio_copy.copy = 0;
+        if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy) == \-1)
+            err(EXIT_FAILURE, "ioctl\-UFFDIO_COPY");
+\&
+        printf("        (uffdio_copy.copy returned %"PRId64")\en",
+               uffdio_copy.copy);
+    }
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int        s;
+    char       c;
+    char       *addr;   /* Start of region handled by userfaultfd */
+    long       uffd;    /* userfaultfd file descriptor */
+    size_t     len, l;  /* Length of region handled by userfaultfd */
+    pthread_t  thr;     /* ID of thread that handles page faults */
+    struct uffdio_api       uffdio_api;
+    struct uffdio_register  uffdio_register;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s num\-pages\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    page_size = sysconf(_SC_PAGE_SIZE);
+    len = strtoull(argv[1], NULL, 0) * page_size;
+\&
+    /* Create and enable userfaultfd object. */
+\&
+    uffd = syscall(SYS_userfaultfd, O_CLOEXEC | O_NONBLOCK);
+    if (uffd == \-1)
+        err(EXIT_FAILURE, "userfaultfd");
+\&
+    /* NOTE: Two-step feature handshake is not needed here, since this
+       example doesn't require any specific features.
+\&
+       Programs that *do* should call UFFDIO_API twice: once with
+       `features = 0` to detect features supported by this kernel, and
+       again with the subset of features the program actually wants to
+       enable. */
+    uffdio_api.api = UFFD_API;
+    uffdio_api.features = 0;
+    if (ioctl(uffd, UFFDIO_API, &uffdio_api) == \-1)
+        err(EXIT_FAILURE, "ioctl\-UFFDIO_API");
+\&
+    /* Create a private anonymous mapping. The memory will be
+       demand\-zero paged\-\-that is, not yet allocated. When we
+       actually touch the memory, it will be allocated via
+       the userfaultfd. */
+\&
+    addr = mmap(NULL, len, PROT_READ | PROT_WRITE,
+                MAP_PRIVATE | MAP_ANONYMOUS, \-1, 0);
+    if (addr == MAP_FAILED)
+        err(EXIT_FAILURE, "mmap");
+\&
+    printf("Address returned by mmap() = %p\en", addr);
+\&
+    /* Register the memory range of the mapping we just created for
+       handling by the userfaultfd object. In mode, we request to track
+       missing pages (i.e., pages that have not yet been faulted in). */
+\&
+    uffdio_register.range.start = (unsigned long) addr;
+    uffdio_register.range.len = len;
+    uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+    if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == \-1)
+        err(EXIT_FAILURE, "ioctl\-UFFDIO_REGISTER");
+\&
+    /* Create a thread that will process the userfaultfd events. */
+\&
+    s = pthread_create(&thr, NULL, fault_handler_thread, (void *) uffd);
+    if (s != 0) {
+        errc(EXIT_FAILURE, s, "pthread_create");
+    }
+\&
+    /* Main thread now touches memory in the mapping, touching
+       locations 1024 bytes apart. This will trigger userfaultfd
+       events for all pages in the region. */
+\&
+    l = 0xf;    /* Ensure that faulting address is not on a page
+                   boundary, in order to test that we correctly
+                   handle that case in fault_handling_thread(). */
+    while (l < len) {
+        c = addr[l];
+        printf("Read address %p in %s(): ", addr + l, __func__);
+        printf("%c\en", c);
+        l += 1024;
+        usleep(100000);         /* Slow things down a little */
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fcntl (2),
+.BR ioctl (2),
+.BR ioctl_userfaultfd (2),
+.BR madvise (2),
+.BR mmap (2)
+.P
+.I Documentation/admin\-guide/mm/userfaultfd.rst
+in the Linux kernel source tree
diff --git a/man/man2/ustat.2 b/man/man2/ustat.2
new file mode 100644
index 000000000..2b47f9f54
--- /dev/null
+++ b/man/man2/ustat.2
@@ -0,0 +1,104 @@
+.\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created  1995-08-09 Thomas K. Dyas <tdyas@eden.rutgers.edu>
+.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2001-03-22 by aeb
+.\" Modified 2003-08-04 by aeb
+.\"
+.TH ustat 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ustat \- get filesystem statistics
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.BR "#include <unistd.h>" "    /* libc[45] */"
+.BR "#include <ustat.h>" "     /* glibc2 */"
+.P
+.BI "[[deprecated]] int ustat(dev_t " dev ", struct ustat *" ubuf );
+.fi
+.SH DESCRIPTION
+.BR ustat ()
+returns information about a mounted filesystem.
+.I dev
+is a device number identifying a device containing
+a mounted filesystem.
+.I ubuf
+is a pointer to a
+.I ustat
+structure that contains the following
+members:
+.P
+.in +4n
+.EX
+daddr_t f_tfree;      /* Total free blocks */
+ino_t   f_tinode;     /* Number of free inodes */
+char    f_fname[6];   /* Filsys name */
+char    f_fpack[6];   /* Filsys pack name */
+.EE
+.in
+.P
+The last two fields,
+.I f_fname
+and
+.IR f_fpack ,
+are not implemented and will
+always be filled with null bytes (\[aq]\e0\[aq]).
+.SH RETURN VALUE
+On success, zero is returned and the
+.I ustat
+structure pointed to by
+.I ubuf
+will be filled in.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+.I ubuf
+points outside of your accessible address space.
+.TP
+.B EINVAL
+.I dev
+does not refer to a device containing a mounted filesystem.
+.TP
+.B ENOSYS
+The mounted filesystem referenced by
+.I dev
+does not support this operation,
+or any version of Linux before Linux 1.3.16.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4.
+Removed in glibc 2.28.
+.\" SVr4 documents additional error conditions ENOLINK, ECOMM, and EINTR
+.\" but has no ENOSYS condition.
+.P
+.BR ustat ()
+is deprecated and has been provided only for compatibility.
+All new programs should use
+.BR statfs (2)
+instead.
+.SS HP-UX notes
+The HP-UX version of the
+.I ustat
+structure has an additional field,
+.IR f_blksize ,
+that is unknown elsewhere.
+HP-UX warns:
+For some filesystems, the number of free inodes does not change.
+Such filesystems will return \-1 in the field
+.IR f_tinode .
+.\" Some software tries to use this in order to test whether the
+.\" underlying filesystem is NFS.
+For some filesystems, inodes are dynamically allocated.
+Such filesystems will return the current number of free inodes.
+.SH SEE ALSO
+.BR stat (2),
+.BR statfs (2)
diff --git a/man/man2/utime.2 b/man/man2/utime.2
new file mode 100644
index 000000000..f4858d3e3
--- /dev/null
+++ b/man/man2/utime.2
@@ -0,0 +1,179 @@
+.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by Michael Haardt <michael@moria.de>
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-06-10 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2004-10-10 by Andries Brouwer <aeb@cwi.nl>
+.\"
+.TH utime 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+utime, utimes \- change file last access and modification times
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <utime.h>
+.P
+.BI "int utime(const char *" filename ,
+.BI "          const struct utimbuf *_Nullable " times );
+.P
+.B #include <sys/time.h>
+.P
+.BI "int utimes(const char *" filename ,
+.BI "          const struct timeval " times "[_Nullable 2]);"
+.fi
+.SH DESCRIPTION
+.B Note:
+modern applications may prefer to use the interfaces described in
+.BR utimensat (2).
+.P
+The
+.BR utime ()
+system call
+changes the access and modification times of the inode specified by
+.I filename
+to the
+.IR actime " and " modtime
+fields of
+.I times
+respectively.
+The status change time (ctime) will be set to the current time, even if the
+other time stamps don't actually change.
+.P
+If
+.I times
+is NULL, then the access and modification times of the file are set
+to the current time.
+.P
+Changing timestamps is permitted when: either
+the process has appropriate privileges,
+or the effective user ID equals the user ID
+of the file, or
+.I times
+is NULL and the process has write permission for the file.
+.P
+The
+.I utimbuf
+structure is:
+.P
+.in +4n
+.EX
+struct utimbuf {
+    time_t actime;       /* access time */
+    time_t modtime;      /* modification time */
+};
+.EE
+.in
+.P
+The
+.BR utime ()
+system call
+allows specification of timestamps with a resolution of 1 second.
+.P
+The
+.BR utimes ()
+system call
+is similar, but the
+.I times
+argument refers to an array rather than a structure.
+The elements of this array are
+.I timeval
+structures, which allow a precision of 1 microsecond for specifying timestamps.
+The
+.I timeval
+structure is:
+.P
+.in +4n
+.EX
+struct timeval {
+    long tv_sec;        /* seconds */
+    long tv_usec;       /* microseconds */
+};
+.EE
+.in
+.P
+.I times[0]
+specifies the new access time, and
+.I times[1]
+specifies the new modification time.
+If
+.I times
+is NULL, then analogously to
+.BR utime (),
+the access and modification times of the file are
+set to the current time.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission is denied for one of the directories in
+the path prefix of
+.I path
+(see also
+.BR path_resolution (7)).
+.TP
+.B EACCES
+.I times
+is NULL,
+the caller's effective user ID does not match the owner of the file,
+the caller does not have write access to the file,
+and the caller is not privileged
+(Linux: does not have either the
+.B CAP_DAC_OVERRIDE
+or the
+.B CAP_FOWNER
+capability).
+.TP
+.B ENOENT
+.I filename
+does not exist.
+.TP
+.B EPERM
+.I times
+is not NULL,
+the caller's effective UID does not match the owner of the file,
+and the caller is not privileged
+(Linux: does not have the
+.B CAP_FOWNER
+capability).
+.TP
+.B EROFS
+.I path
+resides on a read-only filesystem.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR utime ()
+SVr4, POSIX.1-2001.
+POSIX.1-2008 marks it as obsolete.
+.TP
+.BR utimes ()
+4.3BSD, POSIX.1-2001.
+.SH NOTES
+Linux does not allow changing the timestamps on an immutable file,
+or setting the timestamps to something other than the current time
+on an append-only file.
+.\"
+.\" In libc4 and libc5,
+.\" .BR utimes ()
+.\" is just a wrapper for
+.\" .BR utime ()
+.\" and hence does not allow a subsecond resolution.
+.SH SEE ALSO
+.BR chattr (1),
+.BR touch (1),
+.BR futimesat (2),
+.BR stat (2),
+.BR utimensat (2),
+.BR futimens (3),
+.BR futimes (3),
+.BR inode (7)
diff --git a/man/man2/utimensat.2 b/man/man2/utimensat.2
new file mode 100644
index 000000000..d58b4d82e
--- /dev/null
+++ b/man/man2/utimensat.2
@@ -0,0 +1,633 @@
+'\" t
+.\" Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk
+.\" <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH utimensat 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+utimensat, futimens \- change file timestamps with nanosecond precision
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" "            /* Definition of " AT_* " constants */"
+.B #include <sys/stat.h>
+.P
+.BI "int utimensat(int " dirfd ", const char *" pathname ,
+.BI "              const struct timespec " times "[_Nullable 2], int " flags );
+.BI "int futimens(int " fd ", const struct timespec " times "[_Nullable 2]);"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR utimensat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.P
+.BR futimens ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.BR utimensat ()
+and
+.BR futimens ()
+update the timestamps of a file with nanosecond precision.
+This contrasts with the historical
+.BR utime (2)
+and
+.BR utimes (2),
+which permit only second and microsecond precision, respectively,
+when setting file timestamps.
+.P
+With
+.BR utimensat ()
+the file is specified via the pathname given in
+.IR pathname .
+With
+.BR futimens ()
+the file whose timestamps are to be updated is specified via
+an open file descriptor,
+.IR fd .
+.P
+For both calls, the new file timestamps are specified in the array
+.IR times :
+.I times[0]
+specifies the new "last access time" (\fIatime\fP);
+.I times[1]
+specifies the new "last modification time" (\fImtime\fP).
+Each of the elements of
+.I times
+specifies a time as the number of seconds and nanoseconds
+since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+This information is conveyed in a
+.BR timespec (3)
+structure.
+.P
+Updated file timestamps are set to the greatest value
+supported by the filesystem that is not greater than the specified time.
+.P
+If the
+.I tv_nsec
+field of one of the
+.I timespec
+structures has the special value
+.BR UTIME_NOW ,
+then the corresponding file timestamp is set to the current time.
+If the
+.I tv_nsec
+field of one of the
+.I timespec
+structures has the special value
+.BR UTIME_OMIT ,
+then the corresponding file timestamp is left unchanged.
+In both of these cases, the value of the corresponding
+.I tv_sec
+.\" 2.6.22 was broken: it is not ignored
+field is ignored.
+.P
+If
+.I times
+is NULL, then both timestamps are set to the current time.
+.\"
+.P
+The status change time (ctime) will be set to the current time, even if the
+other time stamps don't actually change.
+.SS Permissions requirements
+To set both file timestamps to the current time (i.e.,
+.I times
+is NULL, or both
+.I tv_nsec
+fields specify
+.BR UTIME_NOW ),
+either:
+.IP \[bu] 3
+the caller must have write access to the file;
+.\" 2.6.22 was broken here -- for futimens() the check is
+.\" based on whether or not the file descriptor is writable,
+.\" not on whether the caller's effective UID has write
+.\" permission for the file referred to by the descriptor.
+.IP \[bu]
+the caller's effective user ID must match the owner of the file; or
+.IP \[bu]
+the caller must have appropriate privileges.
+.P
+To make any change other than setting both timestamps to the
+current time (i.e.,
+.I times
+is not NULL, and neither
+.I tv_nsec
+field is
+.B UTIME_NOW
+.\" 2.6.22 was broken here:
+.\" both must be something other than *either* UTIME_OMIT *or* UTIME_NOW.
+and neither
+.I tv_nsec
+field is
+.BR UTIME_OMIT ),
+either condition 2 or 3 above must apply.
+.P
+If both
+.I tv_nsec
+fields are specified as
+.BR UTIME_OMIT ,
+then no file ownership or permission checks are performed,
+and the file timestamps are not modified,
+but other error conditions may still be detected.
+.\"
+.\"
+.SS utimensat() specifics
+If
+.I pathname
+is relative, then by default it is interpreted relative to the
+directory referred to by the open file descriptor,
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR utimes (2)
+for a relative pathname).
+See
+.BR openat (2)
+for an explanation of why this can be useful.
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR utimes (2)).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+The
+.I flags
+argument is a bit mask created by ORing together zero or more of
+the following values defined in
+.IR <fcntl.h> :
+.TP
+.BR AT_EMPTY_PATH " (since Linux 5.8)"
+If
+.I pathname
+is an empty string, operate on the file referred to by
+.I dirfd
+(which may have been obtained using the
+.BR open (2)
+.B O_PATH
+flag).
+In this case,
+.I dirfd
+can refer to any type of file, not just a directory.
+If
+.I dirfd
+is
+.BR AT_FDCWD ,
+the call operates on the current working directory.
+This flag is Linux-specific; define
+.B _GNU_SOURCE
+to obtain its definition.
+.TP
+.B AT_SYMLINK_NOFOLLOW
+If
+.I pathname
+specifies a symbolic link, then update the timestamps of the link,
+rather than the file to which it refers.
+.SH RETURN VALUE
+On success,
+.BR utimensat ()
+and
+.BR futimens ()
+return 0.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.I times
+is NULL,
+or both
+.I tv_nsec
+values are
+.BR UTIME_NOW ,
+and the effective user ID of the caller does not match
+the owner of the file,
+the caller does not have write access to the file,
+and the caller is not privileged
+(Linux: does not have either the
+.B CAP_FOWNER
+or the
+.B CAP_DAC_OVERRIDE
+capability).
+.\" But Linux 2.6.22 was broken here.
+.\" Traditionally, utime()/utimes() gives the error EACCES for the case
+.\" where the timestamp pointer argument is NULL (i.e., set both timestamps
+.\" to the current time), and the file is owned by a user other than the
+.\" effective UID of the caller, and the file is not writable by the
+.\" effective UID of the program.  utimensat() also gives this error in the
+.\" same case.  However, in the same circumstances, when utimensat() is
+.\" given a 'times' array in which both tv_nsec fields are UTIME_NOW, which
+.\" provides equivalent functionality to specifying 'times' as NULL, the
+.\" call succeeds.  It should fail with the error EACCES in this case.
+.\"
+.\" POSIX.1-2008 has the following:
+.\" .TP
+.\" .B EACCES
+.\" .RB ( utimensat ())
+.\" .I fd
+.\" was not opened with
+.\" .B O_SEARCH
+.\" and the permissions of the directory to which
+.\" .I fd
+.\" refers do not allow searches.
+.\" EXT2_IMMUTABLE_FL and similar flags for other filesystems.
+.TP
+.B EBADF
+.RB ( futimens ())
+.I fd
+is not a valid file descriptor.
+.TP
+.B EBADF
+.RB ( utimensat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EFAULT
+.I times
+pointed to an invalid address; or,
+.I dirfd
+was
+.BR AT_FDCWD ,
+and
+.I pathname
+is NULL or an invalid address.
+.TP
+.B EINVAL
+Invalid value in
+.IR flags .
+.TP
+.B EINVAL
+Invalid value in one of the
+.I tv_nsec
+fields (value outside range [0, 999,999,999], and not
+.B UTIME_NOW
+or
+.BR UTIME_OMIT );
+or an invalid value in one of the
+.I tv_sec
+fields.
+.TP
+.B EINVAL
+.\" SUSv4 does not specify this error.
+.I pathname
+is NULL,
+.I dirfd
+is not
+.BR AT_FDCWD ,
+and
+.I flags
+contains
+.BR AT_SYMLINK_NOFOLLOW .
+.TP
+.B ELOOP
+.RB ( utimensat ())
+Too many symbolic links were encountered in resolving
+.IR pathname .
+.TP
+.B ENAMETOOLONG
+.RB ( utimensat ())
+.I pathname
+is too long.
+.TP
+.B ENOENT
+.RB ( utimensat ())
+A component of
+.I pathname
+does not refer to an existing directory or file,
+or
+.I pathname
+is an empty string.
+.TP
+.B ENOTDIR
+.RB ( utimensat ())
+.I pathname
+is a relative pathname, but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a file descriptor referring to a directory;
+or, one of the prefix components of
+.I pathname
+is not a directory.
+.TP
+.B EPERM
+The caller attempted to change one or both timestamps to a value
+other than the current time,
+or to change one of the timestamps to the current time while
+leaving the other timestamp unchanged,
+(i.e.,
+.I times
+is not NULL, neither
+.I tv_nsec
+field is
+.BR UTIME_NOW ,
+and neither
+.I tv_nsec
+field is
+.BR UTIME_OMIT )
+and either:
+.RS
+.IP \[bu] 3
+the caller's effective user ID does not match the owner of file,
+and the caller is not privileged
+(Linux: does not have the
+.B CAP_FOWNER
+capability); or,
+.IP \[bu]
+.\" Linux 2.6.22 was broken here:
+.\" it was not consistent with the old utimes() implementation,
+.\" since the case when both tv_nsec fields are UTIME_NOW, was not
+.\" treated like the (times == NULL) case.
+the file is marked append-only or immutable (see
+.BR chattr (1)).
+.\" EXT2_IMMUTABLE_FL EXT_APPEND_FL and similar flags for
+.\" other filesystems.
+.\"
+.\" Why the inconsistency (which is described under NOTES) between
+.\" EACCES and EPERM, where only EPERM tests for append-only.
+.\" (This was also so for the older utimes() implementation.)
+.RE
+.TP
+.B EROFS
+The file is on a read-only filesystem.
+.TP
+.B ESRCH
+.RB ( utimensat ())
+Search permission is denied for one of the prefix components of
+.IR pathname .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR utimensat (),
+.BR futimens ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.SS C library/kernel ABI differences
+On Linux,
+.BR futimens ()
+is a library function implemented on top of the
+.BR utimensat ()
+system call.
+To support this, the Linux
+.BR utimensat ()
+system call implements a nonstandard feature: if
+.I pathname
+is NULL, then the call modifies the timestamps of
+the file referred to by the file descriptor
+.I dirfd
+(which may refer to any type of file).
+Using this feature, the call
+.I "futimens(fd,\ times)"
+is implemented as:
+.P
+.in +4n
+.EX
+utimensat(fd, NULL, times, 0);
+.EE
+.in
+.P
+Note, however, that the glibc wrapper for
+.BR utimensat ()
+disallows passing NULL as the value for
+.IR pathname :
+the wrapper function returns the error
+.B EINVAL
+in this case.
+.SH STANDARDS
+POSIX.1-2008.
+.SH VERSIONS
+.TP
+.BR utimensat ()
+Linux 2.6.22,
+glibc 2.6.
+POSIX.1-2008.
+.TP
+.BR futimens ()
+glibc 2.6.
+POSIX.1-2008.
+.SH NOTES
+.BR utimensat ()
+obsoletes
+.BR futimesat (2).
+.P
+On Linux, timestamps cannot be changed for a file marked immutable,
+and the only change permitted for files marked append-only is to
+set the timestamps to the current time.
+(This is consistent with the historical behavior of
+.BR utime (2)
+and
+.BR utimes (2)
+on Linux.)
+.P
+If both
+.I tv_nsec
+fields are specified as
+.BR UTIME_OMIT ,
+then the Linux implementation of
+.BR utimensat ()
+succeeds even if the file referred to by
+.I dirfd
+and
+.I pathname
+does not exist.
+.SH BUGS
+Several bugs afflict
+.BR utimensat ()
+and
+.BR futimens ()
+before Linux 2.6.26.
+These bugs are either nonconformances with the POSIX.1 draft specification
+or inconsistencies with historical Linux behavior.
+.IP \[bu] 3
+POSIX.1 specifies that if one of the
+.I tv_nsec
+fields has the value
+.B UTIME_NOW
+or
+.BR UTIME_OMIT ,
+then the value of the corresponding
+.I tv_sec
+field should be ignored.
+Instead, the value of the
+.I tv_sec
+field is required to be 0 (or the error
+.B EINVAL
+results).
+.IP \[bu]
+Various bugs mean that for the purposes of permission checking,
+the case where both
+.I tv_nsec
+fields are set to
+.B UTIME_NOW
+isn't always treated the same as specifying
+.I times
+as NULL,
+and the case where one
+.I tv_nsec
+value is
+.B UTIME_NOW
+and the other is
+.B UTIME_OMIT
+isn't treated the same as specifying
+.I times
+as a pointer to an array of structures containing arbitrary time values.
+As a result, in some cases:
+a) file timestamps can be updated by a process that shouldn't have
+permission to perform updates;
+b) file timestamps can't be updated by a process that should have
+permission to perform updates; and
+c) the wrong
+.I errno
+value is returned in case of an error.
+.\" Below, the long description of the errors from the previous bullet
+.\" point (abridged because it's too much detail for a man page).
+.\" .IP \[bu]
+.\" If one of the
+.\" .I tv_nsec
+.\" fields is
+.\" .BR UTIME_OMIT
+.\" and the other is
+.\" .BR UTIME_NOW ,
+.\" then the error
+.\" .B EPERM
+.\" should occur if the process's effective user ID does not match
+.\" the file owner and the process is not privileged.
+.\" Instead, the call successfully changes one of the timestamps.
+.\" .IP \[bu]
+.\" If file is not writable by the effective user ID of the process and
+.\" the process's effective user ID does not match the file owner and
+.\" the process is not privileged,
+.\" and
+.\" .I times
+.\" is NULL, then the error
+.\" .B EACCES
+.\" results.
+.\" This error should also occur if
+.\" .I times
+.\" points to an array of structures in which both
+.\" .I tv_nsec
+.\" fields are
+.\" .BR UTIME_NOW .
+.\" Instead the call succeeds.
+.\" .IP \[bu]
+.\" If a file is marked as append-only (see
+.\" .BR chattr (1)),
+.\" then Linux traditionally
+.\" (i.e.,
+.\" .BR utime (2),
+.\" .BR utimes (2)),
+.\" permits a NULL
+.\" .I times
+.\" argument to be used in order to update both timestamps to the current time.
+.\" For consistency,
+.\" .BR utimensat ()
+.\" and
+.\" .BR futimens ()
+.\" should also produce the same result when given a
+.\" .I times
+.\" argument that points to an array of structures in which both
+.\" .I tv_nsec
+.\" fields are
+.\" .BR UTIME_NOW .
+.\" Instead, the call fails with the error
+.\" .BR EPERM .
+.\" .IP \[bu]
+.\" If a file is marked as immutable (see
+.\" .BR chattr (1)),
+.\" then Linux traditionally
+.\" (i.e.,
+.\" .BR utime (2),
+.\" .BR utimes (2)),
+.\" gives an
+.\" .B EACCES
+.\" error if
+.\" .I times
+.\" is NULL.
+.\" For consistency,
+.\" .BR utimensat ()
+.\" and
+.\" .BR futimens ()
+.\" should also produce the same result when given a
+.\" .I times
+.\" that points to an array of structures in which both
+.\" .I tv_nsec
+.\" fields are
+.\" .BR UTIME_NOW .
+.\" Instead, the call fails with the error
+.\" .BR EPERM .
+.IP \[bu]
+POSIX.1 says that a process that has \fIwrite access to the file\fP
+can make a call with
+.I times
+as NULL, or with
+.I times
+pointing to an array of structures in which both
+.I tv_nsec
+fields are
+.BR UTIME_NOW ,
+in order to update both timestamps to the current time.
+However,
+.BR futimens ()
+instead checks whether the
+.IR "access mode of the file descriptor allows writing" .
+.\" This means that a process with a file descriptor that allows
+.\" writing could change the timestamps of a file for which it
+.\" does not have write permission;
+.\" conversely, a process with a read-only file descriptor won't
+.\" be able to update the timestamps of a file,
+.\" even if it has write permission on the file.
+.SH SEE ALSO
+.BR chattr (1),
+.BR touch (1),
+.BR futimesat (2),
+.BR openat (2),
+.BR stat (2),
+.BR utimes (2),
+.BR futimes (3),
+.BR timespec (3),
+.BR inode (7),
+.BR path_resolution (7),
+.BR symlink (7)
diff --git a/man/man2/utimes.2 b/man/man2/utimes.2
new file mode 100644
index 000000000..04372d49b
--- /dev/null
+++ b/man/man2/utimes.2
@@ -0,0 +1 @@
+.so man2/utime.2
diff --git a/man/man2/vfork.2 b/man/man2/vfork.2
new file mode 100644
index 000000000..0436b0f42
--- /dev/null
+++ b/man/man2/vfork.2
@@ -0,0 +1,316 @@
+.\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl), 1 Nov 1999
+.\" and Copyright 2006, 2012, 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 1999-11-10: Merged text taken from the page contributed by
+.\" Reed H. Petty (rhp@draper.net)
+.\"
+.TH vfork 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+vfork \- create a child process and block parent
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B pid_t vfork(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR vfork ():
+.nf
+    Since glibc 2.12:
+        (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L)
+            || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE
+    Before glibc 2.12:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"     || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+.SS Standard description
+(From POSIX.1)
+The
+.BR vfork ()
+function has the same effect as
+.BR fork (2),
+except that the behavior is undefined if the process created by
+.BR vfork ()
+either modifies any data other than a variable of type
+.I pid_t
+used to store the return value from
+.BR vfork (),
+or returns from the function in which
+.BR vfork ()
+was called, or calls any other function before successfully calling
+.BR _exit (2)
+or one of the
+.BR exec (3)
+family of functions.
+.SS Linux description
+.BR vfork (),
+just like
+.BR fork (2),
+creates a child process of the calling process.
+For details and return value and errors, see
+.BR fork (2).
+.P
+.BR vfork ()
+is a special case of
+.BR clone (2).
+It is used to create new processes without copying the page tables of
+the parent process.
+It may be useful in performance-sensitive applications
+where a child is created which then immediately issues an
+.BR execve (2).
+.P
+.BR vfork ()
+differs from
+.BR fork (2)
+in that the calling thread is suspended until the child terminates
+(either normally,
+by calling
+.BR _exit (2),
+or abnormally, after delivery of a fatal signal),
+or it makes a call to
+.BR execve (2).
+Until that point, the child shares all memory with its parent,
+including the stack.
+The child must not return from the current function or call
+.BR exit (3)
+(which would have the effect of calling exit handlers
+established by the parent process and flushing the parent's
+.BR stdio (3)
+buffers), but may call
+.BR _exit (2).
+.P
+As with
+.BR fork (2),
+the child process created by
+.BR vfork ()
+inherits copies of various of the caller's process attributes
+(e.g., file descriptors, signal dispositions, and current working directory);
+the
+.BR vfork ()
+call differs only in the treatment of the virtual address space,
+as described above.
+.P
+Signals sent to the parent
+arrive after the child releases the parent's memory
+(i.e., after the child terminates
+or calls
+.BR execve (2)).
+.SS Historic description
+Under Linux,
+.BR fork (2)
+is implemented using copy-on-write pages, so the only penalty incurred by
+.BR fork (2)
+is the time and memory required to duplicate the parent's page tables,
+and to create a unique task structure for the child.
+However, in the bad old days a
+.BR fork (2)
+would require making a complete copy of the caller's data space,
+often needlessly, since usually immediately afterward an
+.BR exec (3)
+is done.
+Thus, for greater efficiency, BSD introduced the
+.BR vfork ()
+system call, which did not fully copy the address space of
+the parent process, but borrowed the parent's memory and thread
+of control until a call to
+.BR execve (2)
+or an exit occurred.
+The parent process was suspended while the
+child was using its resources.
+The use of
+.BR vfork ()
+was tricky: for example, not modifying data
+in the parent process depended on knowing which variables were
+held in a register.
+.SH VERSIONS
+The requirements put on
+.BR vfork ()
+by the standards are weaker than those put on
+.BR fork (2),
+so an implementation where the two are synonymous is compliant.
+In particular, the programmer cannot rely on the parent
+remaining blocked until the child either terminates or calls
+.BR execve (2),
+and cannot rely on any specific behavior with respect to shared memory.
+.\" In AIXv3.1 vfork is equivalent to fork.
+.P
+Some consider the semantics of
+.BR vfork ()
+to be an architectural blemish, and the 4.2BSD man page stated:
+\[lq]This system call will be eliminated
+when proper system sharing mechanisms are implemented.
+Users should not depend on the memory sharing semantics of
+.I vfork
+as it will, in that case, be made synonymous to
+.IR fork .\[rq]
+However, even though modern memory management hardware
+has decreased the performance difference between
+.BR fork (2)
+and
+.BR vfork (),
+there are various reasons why Linux and other systems have retained
+.BR vfork ():
+.IP \[bu] 3
+Some performance-critical applications require the small performance
+advantage conferred by
+.BR vfork ().
+.IP \[bu]
+.BR vfork ()
+can be implemented on systems that lack a memory-management unit (MMU), but
+.BR fork (2)
+can't be implemented on such systems.
+(POSIX.1-2008 removed
+.BR vfork ()
+from the standard; the POSIX rationale for the
+.BR posix_spawn (3)
+function notes that that function,
+which provides functionality equivalent to
+.BR fork (2)+\c
+.BR exec (3),
+is designed to be implementable on systems that lack an MMU.)
+.\" http://stackoverflow.com/questions/4259629/what-is-the-difference-between-fork-and-vfork
+.\" http://developers.sun.com/solaris/articles/subprocess/subprocess.html
+.\" http://mailman.uclinux.org/pipermail/uclinux-dev/2009-April/000684.html
+.\"
+.IP \[bu]
+On systems where memory is constrained,
+.BR vfork ()
+avoids the need to temporarily commit memory (see the description of
+.I /proc/sys/vm/overcommit_memory
+in
+.BR proc (5))
+in order to execute a new program.
+(This can be especially beneficial where a large parent process wishes
+to execute a small helper program in a child process.)
+By contrast, using
+.BR fork (2)
+in this scenario requires either committing an amount of memory equal
+to the size of the parent process (if strict overcommitting is in force)
+or overcommitting memory with the risk that a process is terminated
+by the out-of-memory (OOM) killer.
+.SS Linux notes
+Fork handlers established using
+.BR pthread_atfork (3)
+are not called when a multithreaded program employing
+the NPTL threading library calls
+.BR vfork ().
+Fork handlers are called in this case in a program using the
+LinuxThreads threading library.
+(See
+.BR pthreads (7)
+for a description of Linux threading libraries.)
+.P
+A call to
+.BR vfork ()
+is equivalent to calling
+.BR clone (2)
+with
+.I flags
+specified as:
+.P
+.in +4n
+.EX
+ CLONE_VM | CLONE_VFORK | SIGCHLD
+.EE
+.in
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD; POSIX.1-2001 (but marked OBSOLETE).
+POSIX.1-2008 removes the specification of
+.BR vfork ().
+.P
+The
+.BR vfork ()
+system call appeared in 3.0BSD.
+.\" In the release notes for 4.2BSD Sam Leffler wrote: `vfork: Is still
+.\" present, but definitely on its way out'.
+In 4.4BSD it was made synonymous to
+.BR fork (2)
+but NetBSD introduced it again;
+see
+.UR http://www.netbsd.org\:/Documentation\:/kernel\:/vfork.html
+.UE .
+In Linux, it has been equivalent to
+.BR fork (2)
+until Linux 2.2.0-pre6 or so.
+Since Linux 2.2.0-pre9 (on i386, somewhat later on
+other architectures) it is an independent system call.
+Support was added in glibc 2.0.112.
+.\"
+.SH CAVEATS
+The child process should take care not to modify the memory in unintended ways,
+since such changes will be seen by the parent process once
+the child terminates or executes another program.
+In this regard, signal handlers can be especially problematic:
+if a signal handler that is invoked in the child of
+.BR vfork ()
+changes memory, those changes may result in an inconsistent process state
+from the perspective of the parent process
+(e.g., memory changes would be visible in the parent,
+but changes to the state of open file descriptors would not be visible).
+.P
+When
+.BR vfork ()
+is called in a multithreaded process,
+only the calling thread is suspended until the child terminates
+or executes a new program.
+This means that the child is sharing an address space with other running code.
+This can be dangerous if another thread in the parent process
+changes credentials (using
+.BR setuid (2)
+or similar),
+since there are now two processes with different privilege levels
+running in the same address space.
+As an example of the dangers,
+suppose that a multithreaded program running as root creates a child using
+.BR vfork ().
+After the
+.BR vfork (),
+a thread in the parent process drops the process to an unprivileged user
+in order to run some untrusted code
+(e.g., perhaps via plug-in opened with
+.BR dlopen (3)).
+In this case, attacks are possible where the parent process uses
+.BR mmap (2)
+to map in code that will be executed by the privileged child process.
+.\"
+.SH BUGS
+Details of the signal handling are obscure and differ between systems.
+The BSD man page states:
+"To avoid a possible deadlock situation, processes that are children
+in the middle of a
+.BR vfork ()
+are never sent
+.B SIGTTOU
+or
+.B SIGTTIN
+signals; rather, output or
+.IR ioctl s
+are allowed and input attempts result in an end-of-file indication."
+.\"
+.\" As far as I can tell, the following is not true in Linux 2.6.19:
+.\" Currently (Linux 2.3.25),
+.\" .BR strace (1)
+.\" cannot follow
+.\" .BR vfork ()
+.\" and requires a kernel patch.
+.SH SEE ALSO
+.BR clone (2),
+.BR execve (2),
+.BR _exit (2),
+.BR fork (2),
+.BR unshare (2),
+.BR wait (2)
diff --git a/man/man2/vhangup.2 b/man/man2/vhangup.2
new file mode 100644
index 000000000..c0f68f37a
--- /dev/null
+++ b/man/man2/vhangup.2
@@ -0,0 +1,58 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"
+.TH vhangup 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+vhangup \- virtually hangup the current terminal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B int vhangup(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR vhangup ():
+.nf
+    Since glibc 2.21:
+.\"		commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+.BR vhangup ()
+simulates a hangup on the current terminal.
+This call arranges for other
+users to have a \*(lqclean\*(rq terminal at login time.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EPERM
+The calling process has insufficient privilege to call
+.BR vhangup ();
+the
+.B CAP_SYS_TTY_CONFIG
+capability is required.
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR init (1),
+.BR capabilities (7)
diff --git a/man/man2/vm86.2 b/man/man2/vm86.2
new file mode 100644
index 000000000..2e0feaf5a
--- /dev/null
+++ b/man/man2/vm86.2
@@ -0,0 +1,58 @@
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\" Copyright 1997 Andries E. Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH vm86 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+vm86old, vm86 \- enter virtual 8086 mode
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/vm86.h>
+.P
+.BI "int vm86old(struct vm86_struct *" info );
+.BI "int vm86(unsigned long " fn ", struct vm86plus_struct *" v86 );
+.fi
+.SH DESCRIPTION
+The system call
+.BR vm86 ()
+was introduced in Linux 0.97p2.
+In Linux 2.1.15 and 2.0.28, it was renamed to
+.BR vm86old (),
+and a new
+.BR vm86 ()
+was introduced.
+The definition of
+.I struct vm86_struct
+was changed
+in 1.1.8 and 1.1.9.
+.P
+These calls cause the process to enter VM86 mode (virtual-8086 in Intel
+literature), and are used by
+.BR dosemu .
+.P
+VM86 mode is an emulation of real mode within a protected mode task.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+This return value is specific to i386 and indicates a problem with getting
+user-space data.
+.TP
+.B ENOSYS
+This return value indicates the call is not implemented on the present
+architecture.
+.TP
+.B EPERM
+Saved kernel stack exists.
+(This is a kernel sanity check; the saved
+stack should exist only within vm86 mode itself.)
+.SH STANDARDS
+Linux on 32-bit Intel processors.
diff --git a/man/man2/vm86old.2 b/man/man2/vm86old.2
new file mode 100644
index 000000000..bf2581d4c
--- /dev/null
+++ b/man/man2/vm86old.2
@@ -0,0 +1 @@
+.so man2/vm86.2
diff --git a/man/man2/vmsplice.2 b/man/man2/vmsplice.2
new file mode 100644
index 000000000..819465b23
--- /dev/null
+++ b/man/man2/vmsplice.2
@@ -0,0 +1,162 @@
+.\" This manpage is Copyright (C) 2006 Jens Axboe
+.\" and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH vmsplice 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+vmsplice \- splice user pages to/from a pipe
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <fcntl.h>
+.P
+.BI "ssize_t vmsplice(int " fd ", const struct iovec *" iov ,
+.BI "                 size_t " nr_segs ", unsigned int " flags );
+.fi
+.\" Return type was long before glibc 2.7
+.SH DESCRIPTION
+.\" Linus: vmsplice() system call to basically do a "write to
+.\" the buffer", but using the reference counting and VM traversal
+.\" to actually fill the buffer. This means that the user needs to
+.\" be careful not to reuse the user-space buffer it spliced into
+.\" the kernel-space one (contrast this to "write()", which copies
+.\" the actual data, and you can thus reuse the buffer immediately
+.\" after a successful write), but that is often easy to do.
+If
+.I fd
+is opened for writing, the
+.BR vmsplice ()
+system call maps
+.I nr_segs
+ranges of user memory described by
+.I iov
+into a pipe.
+If
+.I fd
+is opened for reading,
+.\" Since Linux 2.6.23
+.\" commit 6a14b90bb6bc7cd83e2a444bf457a2ea645cbfe7
+the
+.BR vmsplice ()
+system call fills
+.I nr_segs
+ranges of user memory described by
+.I iov
+from a pipe.
+The file descriptor
+.I fd
+must refer to a pipe.
+.P
+The pointer
+.I iov
+points to an array of
+.I iovec
+structures as described in
+.BR iovec (3type).
+.P
+The
+.I flags
+argument is a bit mask that is composed by ORing together
+zero or more of the following values:
+.TP
+.B SPLICE_F_MOVE
+Unused for
+.BR vmsplice ();
+see
+.BR splice (2).
+.TP
+.B SPLICE_F_NONBLOCK
+.\" Not used for vmsplice
+.\" May be in the future -- therefore EAGAIN
+Do not block on I/O; see
+.BR splice (2)
+for further details.
+.TP
+.B SPLICE_F_MORE
+Currently has no effect for
+.BR vmsplice (),
+but may be implemented in the future; see
+.BR splice (2).
+.TP
+.B SPLICE_F_GIFT
+The user pages are a gift to the kernel.
+The application may not modify this memory ever,
+.\" FIXME . Explain the following line in a little more detail:
+otherwise the page cache and on-disk data may differ.
+Gifting pages to the kernel means that a subsequent
+.BR splice (2)
+.B SPLICE_F_MOVE
+can successfully move the pages;
+if this flag is not specified, then a subsequent
+.BR splice (2)
+.B SPLICE_F_MOVE
+must copy the pages.
+Data must also be properly page aligned, both in memory and length.
+.\" FIXME
+.\" It looks like the page-alignment requirement went away with
+.\" commit bd1a68b59c8e3bce45fb76632c64e1e063c3962d
+.\"
+.\" .... if we expect to later SPLICE_F_MOVE to the cache.
+.SH RETURN VALUE
+Upon successful completion,
+.BR vmsplice ()
+returns the number of bytes transferred to the pipe.
+On error,
+.BR vmsplice ()
+returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+.B SPLICE_F_NONBLOCK
+was specified in
+.IR flags ,
+and the operation would block.
+.TP
+.B EBADF
+.I fd
+either not valid, or doesn't refer to a pipe.
+.TP
+.B EINVAL
+.I nr_segs
+is greater than
+.BR IOV_MAX ;
+or memory not aligned if
+.B SPLICE_F_GIFT
+set.
+.TP
+.B ENOMEM
+Out of memory.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.17,
+glibc 2.5.
+.SH NOTES
+.BR vmsplice ()
+follows the other vectorized read/write type functions when it comes to
+limitations on the number of segments being passed in.
+This limit is
+.B IOV_MAX
+as defined in
+.IR <limits.h> .
+Currently,
+.\" UIO_MAXIOV in kernel source
+this limit is 1024.
+.P
+.\" commit 6a14b90bb6bc7cd83e2a444bf457a2ea645cbfe7
+.BR vmsplice ()
+really supports true splicing only from user memory to a pipe.
+In the opposite direction, it actually just copies the data to user space.
+But this makes the interface nice and symmetric and enables people to build on
+.BR vmsplice ()
+with room for future improvement in performance.
+.SH SEE ALSO
+.BR splice (2),
+.BR tee (2),
+.BR pipe (7)
diff --git a/man/man2/vserver.2 b/man/man2/vserver.2
new file mode 100644
index 000000000..5d25ea6ce
--- /dev/null
+++ b/man/man2/vserver.2
@@ -0,0 +1 @@
+.so man2/unimplemented.2
diff --git a/man/man2/wait.2 b/man/man2/wait.2
new file mode 100644
index 000000000..2e0e9c254
--- /dev/null
+++ b/man/man2/wait.2
@@ -0,0 +1,720 @@
+.\" Copyright (c) 1993 by Thomas Koenig <ig25@rz.uni-karlsruhe.de>
+.\" and Copyright (c) 2004 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 13:30:06 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Aug 21 17:42:42 1994 by Rik Faith <faith@cs.unc.edu>
+.\"          (Thanks to Koen Holtman <koen@win.tue.nl>)
+.\" Modified Wed May 17 15:54:12 1995 by Rik Faith <faith@cs.unc.edu>
+.\"           To remove *'s from status in macros (Thanks to Michael Shields).
+.\" Modified as suggested by Nick Duffek <nsd@bbc.com>, aeb, 960426
+.\" Modified Mon Jun 23 14:09:52 1997 by aeb - add EINTR.
+.\" Modified Thu Nov 26 02:12:45 1998 by aeb - add SIGCHLD stuff.
+.\" Modified Mon Jul 24 21:37:38 2000 by David A. Wheeler
+.\"          <dwheeler@dwheeler.com> - noted thread issues.
+.\" Modified 26 Jun 01 by Michael Kerrisk
+.\"          Added __WCLONE, __WALL, and __WNOTHREAD descriptions
+.\" Modified 2001-09-25, aeb
+.\" Modified 26 Jun 01 by Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"	Updated notes on setting disposition of SIGCHLD to SIG_IGN
+.\" 2004-11-11, mtk
+.\"	Added waitid(2); added WCONTINUED and WIFCONTINUED()
+.\"	Added text on SA_NOCLDSTOP
+.\"	Updated discussion of SA_NOCLDWAIT to reflect 2.6 behavior
+.\"	Much other text rewritten
+.\" 2005-05-10, mtk, __W* flags can't be used with waitid()
+.\" 2008-07-04, mtk, removed erroneous text about SA_NOCLDSTOP
+.\"
+.TH wait 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wait, waitpid, waitid \- wait for process to change state
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/wait.h>
+.P
+.BI "pid_t wait(int *_Nullable " "wstatus" );
+.BI "pid_t waitpid(pid_t " pid ", int *_Nullable " wstatus ", int " options );
+.P
+.BI "int waitid(idtype_t " idtype ", id_t " id \
+", siginfo_t *" infop ", int " options );
+                /* This is the glibc and POSIX interface; see
+                   NOTES for information on the raw system call. */
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR waitid ():
+.nf
+    Since glibc 2.26:
+        _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200809L
+.\"    (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+    glibc 2.25 and earlier:
+        _XOPEN_SOURCE
+            || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+            || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+All of these system calls are used to wait for state changes
+in a child of the calling process, and obtain information
+about the child whose state has changed.
+A state change is considered to be: the child terminated;
+the child was stopped by a signal; or the child was resumed by a signal.
+In the case of a terminated child, performing a wait allows
+the system to release the resources associated with the child;
+if a wait is not performed, then the terminated child remains in
+a "zombie" state (see NOTES below).
+.P
+If a child has already changed state, then these calls return immediately.
+Otherwise, they block until either a child changes state or
+a signal handler interrupts the call (assuming that system calls
+are not automatically restarted using the
+.B SA_RESTART
+flag of
+.BR sigaction (2)).
+In the remainder of this page, a child whose state has changed
+and which has not yet been waited upon by one of these system
+calls is termed
+.IR waitable .
+.SS wait() and waitpid()
+The
+.BR wait ()
+system call suspends execution of the calling thread until one of its
+children terminates.
+The call
+.I wait(&wstatus)
+is equivalent to:
+.P
+.in +4n
+.EX
+waitpid(\-1, &wstatus, 0);
+.EE
+.in
+.P
+The
+.BR waitpid ()
+system call suspends execution of the calling thread until a
+child specified by
+.I pid
+argument has changed state.
+By default,
+.BR waitpid ()
+waits only for terminated children, but this behavior is modifiable
+via the
+.I options
+argument, as described below.
+.P
+The value of
+.I pid
+can be:
+.TP
+.RB "< " \-1
+meaning wait for any child process whose process group ID is
+equal to the absolute value of
+.IR pid .
+.TP
+.B \-1
+meaning wait for any child process.
+.TP
+.B 0
+meaning wait for any child process whose process group ID is
+equal to that of the calling process at the time of the call to
+.BR waitpid ().
+.TP
+.RB "> " 0
+meaning wait for the child whose process ID is equal to the
+value of
+.IR pid .
+.P
+The value of
+.I options
+is an OR of zero or more of the following constants:
+.TP
+.B WNOHANG
+return immediately if no child has exited.
+.TP
+.B WUNTRACED
+also return if a child has stopped
+(but not traced via
+.BR ptrace (2)).
+Status for
+.I traced
+children which have stopped is provided
+even if this option is not specified.
+.TP
+.BR WCONTINUED " (since Linux 2.6.10)"
+also return if a stopped child has been resumed by delivery of
+.BR SIGCONT .
+.P
+(For Linux-only options, see below.)
+.P
+If
+.I wstatus
+is not NULL,
+.BR wait ()
+and
+.BR waitpid ()
+store status information in the \fIint\fP to which it points.
+This integer can be inspected with the following macros (which
+take the integer itself as an argument, not a pointer to it,
+as is done in
+.BR wait ()
+and
+.BR waitpid ()!):
+.TP
+.BI WIFEXITED( wstatus )
+returns true if the child terminated normally, that is,
+by calling
+.BR exit (3)
+or
+.BR _exit (2),
+or by returning from main().
+.TP
+.BI WEXITSTATUS( wstatus )
+returns the exit status of the child.
+This consists of the least significant 8 bits of the
+.I status
+argument that the child specified in a call to
+.BR exit (3)
+or
+.BR _exit (2)
+or as the argument for a return statement in main().
+This macro should be employed only if
+.B WIFEXITED
+returned true.
+.TP
+.BI WIFSIGNALED( wstatus )
+returns true if the child process was terminated by a signal.
+.TP
+.BI WTERMSIG( wstatus )
+returns the number of the signal that caused the child process to
+terminate.
+This macro should be employed only if
+.B WIFSIGNALED
+returned true.
+.TP
+.BI WCOREDUMP( wstatus )
+returns true if the child produced a core dump (see
+.BR core (5)).
+This macro should be employed only if
+.B WIFSIGNALED
+returned true.
+.IP
+This macro is not specified in POSIX.1-2001 and is not available on
+some UNIX implementations (e.g., AIX, SunOS).
+Therefore, enclose its use inside
+.IR "#ifdef WCOREDUMP ... #endif" .
+.TP
+.BI WIFSTOPPED( wstatus )
+returns true if the child process was stopped by delivery of a signal;
+this is possible only if the call was done using
+.B WUNTRACED
+or when the child is being traced (see
+.BR ptrace (2)).
+.TP
+.BI WSTOPSIG( wstatus )
+returns the number of the signal which caused the child to stop.
+This macro should be employed only if
+.B WIFSTOPPED
+returned true.
+.TP
+.BI WIFCONTINUED( wstatus )
+(since Linux 2.6.10)
+returns true if the child process was resumed by delivery of
+.BR SIGCONT .
+.SS waitid()
+The
+.BR waitid ()
+system call (available since Linux 2.6.9) provides more precise
+control over which child state changes to wait for.
+.P
+The
+.I idtype
+and
+.I id
+arguments select the child(ren) to wait for, as follows:
+.TP
+.IR idtype " == " \fBP_PID\fP
+Wait for the child whose process ID matches
+.IR id .
+.TP
+.IR idtype " == " \fBP_PIDFD\fP " (since Linux 5.4)"
+.\" commit 3695eae5fee0605f316fbaad0b9e3de791d7dfaf
+Wait for the child referred to by the PID file descriptor specified in
+.IR id .
+(See
+.BR pidfd_open (2)
+for further information on PID file descriptors.)
+.TP
+.IR idtype " == " \fBP_PGID\fP
+Wait for any child whose process group ID matches
+.IR id .
+Since Linux 5.4,
+.\" commit 821cc7b0b205c0df64cce59aacc330af251fa8f7
+if
+.I id
+is zero, then wait for any child that is in the same process group
+as the caller's process group at the time of the call.
+.TP
+.IR idtype " == " \fBP_ALL\fP
+Wait for any child;
+.I id
+is ignored.
+.P
+The child state changes to wait for are specified by ORing
+one or more of the following flags in
+.IR options :
+.TP
+.B WEXITED
+Wait for children that have terminated.
+.TP
+.B WSTOPPED
+Wait for children that have been stopped by delivery of a signal.
+.TP
+.B WCONTINUED
+Wait for (previously stopped) children that have been
+resumed by delivery of
+.BR SIGCONT .
+.P
+The following flags may additionally be ORed in
+.IR options :
+.TP
+.B WNOHANG
+As for
+.BR waitpid ().
+.TP
+.B WNOWAIT
+Leave the child in a waitable state; a later wait call
+can be used to again retrieve the child status information.
+.P
+Upon successful return,
+.BR waitid ()
+fills in the following fields of the
+.I siginfo_t
+structure pointed to by
+.IR infop :
+.TP
+\fIsi_pid\fP
+The process ID of the child.
+.TP
+\fIsi_uid\fP
+The real user ID of the child.
+(This field is not set on most other implementations.)
+.TP
+\fIsi_signo\fP
+Always set to
+.BR SIGCHLD .
+.TP
+\fIsi_status\fP
+Either the exit status of the child, as given to
+.BR _exit (2)
+(or
+.BR exit (3)),
+or the signal that caused the child to terminate, stop, or continue.
+The
+.I si_code
+field can be used to determine how to interpret this field.
+.TP
+\fIsi_code\fP
+Set to one of:
+.B CLD_EXITED
+(child called
+.BR _exit (2));
+.B CLD_KILLED
+(child killed by signal);
+.B CLD_DUMPED
+(child killed by signal, and dumped core);
+.B CLD_STOPPED
+(child stopped by signal);
+.B CLD_TRAPPED
+(traced child has trapped); or
+.B CLD_CONTINUED
+(child continued by
+.BR SIGCONT ).
+.P
+If
+.B WNOHANG
+was specified in
+.I options
+and there were no children in a waitable state, then
+.BR waitid ()
+returns 0 immediately and
+the state of the
+.I siginfo_t
+structure pointed to by
+.I infop
+depends on the implementation.
+To (portably) distinguish this case from that where a child was in a
+waitable state, zero out the
+.I si_pid
+field before the call and check for a nonzero value in this field
+after the call returns.
+.P
+POSIX.1-2008 Technical Corrigendum 1 (2013) adds the requirement that when
+.B WNOHANG
+is specified in
+.I options
+and there were no children in a waitable state, then
+.BR waitid ()
+should zero out the
+.I si_pid
+and
+.I si_signo
+fields of the structure.
+On Linux and other implementations that adhere to this requirement,
+it is not necessary to zero out the
+.I si_pid
+field before calling
+.BR waitid ().
+However,
+not all implementations follow the POSIX.1 specification on this point.
+.\" POSIX.1-2001 leaves this possibility unspecified; most
+.\" implementations (including Linux) zero out the structure
+.\" in this case, but at least one implementation (AIX 5.1)
+.\" does not -- MTK Nov 04
+.SH RETURN VALUE
+.BR wait ():
+on success, returns the process ID of the terminated child;
+on failure, \-1 is returned.
+.P
+.BR waitpid ():
+on success, returns the process ID of the child whose state has changed;
+if
+.B WNOHANG
+was specified and one or more child(ren) specified by
+.I pid
+exist, but have not yet changed state, then 0 is returned.
+On failure, \-1 is returned.
+.P
+.BR waitid ():
+returns 0 on success or
+if
+.B WNOHANG
+was specified and no child(ren) specified by
+.I id
+has yet changed state;
+on failure, \-1 is returned.
+.\" FIXME As reported by Vegard Nossum, if infop is NULL, then waitid()
+.\" returns the PID of the child.  Either this is a bug, or it is intended
+.\" behavior that needs to be documented.  See my Jan 2009 LKML mail
+.\" "waitid() return value strangeness when infop is NULL".
+.P
+On failure, each of these calls sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The PID file descriptor specified in
+.I id
+is nonblocking and the process that it refers to has not terminated.
+.TP
+.B ECHILD
+(for
+.BR wait ())
+The calling process does not have any unwaited-for children.
+.TP
+.B ECHILD
+(for
+.BR waitpid ()
+or
+.BR waitid ())
+The process specified by
+.I pid
+.RB ( waitpid ())
+or
+.I idtype
+and
+.I id
+.RB ( waitid ())
+does not exist or is not a child of the calling process.
+(This can happen for one's own child if the action for
+.B SIGCHLD
+is set to
+.BR SIG_IGN .
+See also the \fILinux Notes\fP section about threads.)
+.TP
+.B EINTR
+.B WNOHANG
+was not set and an unblocked signal or a
+.B SIGCHLD
+was caught; see
+.BR signal (7).
+.TP
+.B EINVAL
+The
+.I options
+argument was invalid.
+.TP
+.B ESRCH
+(for
+.BR wait ()
+or
+.BR waitpid ())
+.I pid
+is equal to
+.BR INT_MIN .
+.SH VERSIONS
+.SS C library/kernel differences
+.BR wait ()
+is actually a library function that (in glibc) is implemented as a call to
+.BR wait4 (2).
+.P
+On some architectures, there is no
+.BR waitpid ()
+system call;
+.\" e.g., i386 has the system call, but not x86-64
+instead, this interface is implemented via a C library
+wrapper function that calls
+.BR wait4 (2).
+.P
+The raw
+.BR waitid ()
+system call takes a fifth argument, of type
+.IR "struct rusage\ *" .
+If this argument is non-NULL,
+then it is used to return resource usage information about the child,
+in the same manner as
+.BR wait4 (2).
+See
+.BR getrusage (2)
+for details.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+SVr4, 4.3BSD, POSIX.1-2001.
+.SH NOTES
+A child that terminates, but has not been waited for becomes a "zombie".
+The kernel maintains a minimal set of information about the zombie
+process (PID, termination status, resource usage information)
+in order to allow the parent to later perform a wait to obtain
+information about the child.
+As long as a zombie is not removed from the system via a wait,
+it will consume a slot in the kernel process table, and if
+this table fills, it will not be possible to create further processes.
+If a parent process terminates, then its "zombie" children (if any)
+are adopted by
+.BR init (1),
+(or by the nearest "subreaper" process as defined through the use of the
+.BR prctl (2)
+.B PR_SET_CHILD_SUBREAPER
+operation);
+.BR init (1)
+automatically performs a wait to remove the zombies.
+.P
+POSIX.1-2001 specifies that if the disposition of
+.B SIGCHLD
+is set to
+.B SIG_IGN
+or the
+.B SA_NOCLDWAIT
+flag is set for
+.B SIGCHLD
+(see
+.BR sigaction (2)),
+then children that terminate do not become zombies and a call to
+.BR wait ()
+or
+.BR waitpid ()
+will block until all children have terminated, and then fail with
+.I errno
+set to
+.BR ECHILD .
+(The original POSIX standard left the behavior of setting
+.B SIGCHLD
+to
+.B SIG_IGN
+unspecified.
+Note that even though the default disposition of
+.B SIGCHLD
+is "ignore", explicitly setting the disposition to
+.B SIG_IGN
+results in different treatment of zombie process children.)
+.P
+Linux 2.6 conforms to the POSIX requirements.
+However, Linux 2.4 (and earlier) does not:
+if a
+.BR wait ()
+or
+.BR waitpid ()
+call is made while
+.B SIGCHLD
+is being ignored, the call behaves just as though
+.B SIGCHLD
+were not being ignored, that is, the call blocks until the next child
+terminates and then returns the process ID and status of that child.
+.SS Linux notes
+In the Linux kernel, a kernel-scheduled thread is not a distinct
+construct from a process.
+Instead, a thread is simply a process
+that is created using the Linux-unique
+.BR clone (2)
+system call; other routines such as the portable
+.BR pthread_create (3)
+call are implemented using
+.BR clone (2).
+Before Linux 2.4, a thread was just a special case of a process,
+and as a consequence one thread could not wait on the children
+of another thread, even when the latter belongs to the same thread group.
+However, POSIX prescribes such functionality, and since Linux 2.4
+a thread can, and by default will, wait on children of other threads
+in the same thread group.
+.P
+The following Linux-specific
+.I options
+are for use with children created using
+.BR clone (2);
+they can also, since Linux 4.7,
+.\" commit 91c4e8ea8f05916df0c8a6f383508ac7c9e10dba
+be used with
+.BR waitid ():
+.TP
+.B __WCLONE
+.\" since 0.99pl10
+Wait for "clone" children only.
+If omitted, then wait for "non-clone" children only.
+(A "clone" child is one which delivers no signal, or a signal other than
+.B SIGCHLD
+to its parent upon termination.)
+This option is ignored if
+.B __WALL
+is also specified.
+.TP
+.BR __WALL " (since Linux 2.4)"
+.\" since patch-2.3.48
+Wait for all children, regardless of
+type ("clone" or "non-clone").
+.TP
+.BR __WNOTHREAD " (since Linux 2.4)"
+.\" since patch-2.4.0-test8
+Do not wait for children of other threads in
+the same thread group.
+This was the default before Linux 2.4.
+.P
+Since Linux 4.7,
+.\" commit bf959931ddb88c4e4366e96dd22e68fa0db9527c
+.\" prevents cases where an unreapable zombie is created if
+.\" /sbin/init doesn't use __WALL.
+the
+.B __WALL
+flag is automatically implied if the child is being ptraced.
+.SH BUGS
+According to POSIX.1-2008, an application calling
+.BR waitid ()
+must ensure that
+.I infop
+points to a
+.I siginfo_t
+structure (i.e., that it is a non-null pointer).
+On Linux, if
+.I infop
+is NULL,
+.BR waitid ()
+succeeds, and returns the process ID of the waited-for child.
+Applications should avoid relying on this inconsistent,
+nonstandard, and unnecessary feature.
+.SH EXAMPLES
+.\" fork.2 refers to this example program.
+The following program demonstrates the use of
+.BR fork (2)
+and
+.BR waitpid ().
+The program creates a child process.
+If no command-line argument is supplied to the program,
+then the child suspends its execution using
+.BR pause (2),
+to allow the user to send signals to the child.
+Otherwise, if a command-line argument is supplied,
+then the child exits immediately,
+using the integer supplied on the command line as the exit status.
+The parent process executes a loop that monitors the child using
+.BR waitpid (),
+and uses the W*() macros described above to analyze the wait status value.
+.P
+The following shell session demonstrates the use of the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out &"
+Child PID is 32360
+[1] 32359
+.RB "$" " kill \-STOP 32360"
+stopped by signal 19
+.RB "$" " kill \-CONT 32360"
+continued
+.RB "$" " kill \-TERM 32360"
+killed by signal 15
+[1]+  Done                    ./a.out
+$
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (wait.c)
+.EX
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int    wstatus;
+    pid_t  cpid, w;
+\&
+    cpid = fork();
+    if (cpid == \-1) {
+        perror("fork");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (cpid == 0) {            /* Code executed by child */
+        printf("Child PID is %jd\en", (intmax_t) getpid());
+        if (argc == 1)
+            pause();                    /* Wait for signals */
+        _exit(atoi(argv[1]));
+\&
+    } else {                    /* Code executed by parent */
+        do {
+            w = waitpid(cpid, &wstatus, WUNTRACED | WCONTINUED);
+            if (w == \-1) {
+                perror("waitpid");
+                exit(EXIT_FAILURE);
+            }
+\&
+            if (WIFEXITED(wstatus)) {
+                printf("exited, status=%d\en", WEXITSTATUS(wstatus));
+            } else if (WIFSIGNALED(wstatus)) {
+                printf("killed by signal %d\en", WTERMSIG(wstatus));
+            } else if (WIFSTOPPED(wstatus)) {
+                printf("stopped by signal %d\en", WSTOPSIG(wstatus));
+            } else if (WIFCONTINUED(wstatus)) {
+                printf("continued\en");
+            }
+        } while (!WIFEXITED(wstatus) && !WIFSIGNALED(wstatus));
+        exit(EXIT_SUCCESS);
+    }
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR _exit (2),
+.BR clone (2),
+.BR fork (2),
+.BR kill (2),
+.BR ptrace (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR wait4 (2),
+.BR pthread_create (3),
+.BR core (5),
+.BR credentials (7),
+.BR signal (7)
diff --git a/man/man2/wait3.2 b/man/man2/wait3.2
new file mode 100644
index 000000000..097794b11
--- /dev/null
+++ b/man/man2/wait3.2
@@ -0,0 +1 @@
+.so man2/wait4.2
diff --git a/man/man2/wait4.2 b/man/man2/wait4.2
new file mode 100644
index 000000000..27d908997
--- /dev/null
+++ b/man/man2/wait4.2
@@ -0,0 +1,169 @@
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright (c) 2004 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 13:32:44 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon Jun 23 14:09:52 1997 by aeb - add EINTR.
+.\" Modified Tue Jul  7 12:26:42 1998 by aeb - changed return value wait3
+.\" Modified 2004-11-11, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Rewrote much of this page, and removed much duplicated text,
+.\"		replacing with pointers to wait.2
+.\"
+.TH wait4 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wait3, wait4 \- wait for process to change state, BSD style
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/wait.h>
+.P
+.BI "pid_t wait3(int *_Nullable " "wstatus" ", int " options ,
+.BI "            struct rusage *_Nullable " rusage );
+.BI "pid_t wait4(pid_t " pid ", int *_Nullable " wstatus ", int " options ,
+.BI "            struct rusage *_Nullable " rusage );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wait3 ():
+.nf
+    Since glibc 2.26:
+        _DEFAULT_SOURCE
+            || (_XOPEN_SOURCE >= 500 &&
+                ! (_POSIX_C_SOURCE >= 200112L
+                   || _XOPEN_SOURCE >= 600))
+    From glibc 2.19 to glibc 2.25:
+        _DEFAULT_SOURCE || _XOPEN_SOURCE >= 500
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"          || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.P
+.BR wait4 ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+These functions are nonstandard; in new programs, the use of
+.BR waitpid (2)
+or
+.BR waitid (2)
+is preferable.
+.P
+The
+.BR wait3 ()
+and
+.BR wait4 ()
+system calls are similar to
+.BR waitpid (2),
+but additionally return resource usage information about the
+child in the structure pointed to by
+.IR rusage .
+.P
+Other than the use of the
+.I rusage
+argument, the following
+.BR wait3 ()
+call:
+.P
+.in +4n
+.EX
+wait3(wstatus, options, rusage);
+.EE
+.in
+.P
+is equivalent to:
+.P
+.in +4n
+.EX
+waitpid(\-1, wstatus, options);
+.EE
+.in
+.P
+Similarly, the following
+.BR wait4 ()
+call:
+.P
+.in +4n
+.EX
+wait4(pid, wstatus, options, rusage);
+.EE
+.in
+.P
+is equivalent to:
+.P
+.in +4n
+.EX
+waitpid(pid, wstatus, options);
+.EE
+.in
+.P
+In other words,
+.BR wait3 ()
+waits of any child, while
+.BR wait4 ()
+can be used to select a specific child, or children, on which to wait.
+See
+.BR wait (2)
+for further details.
+.P
+If
+.I rusage
+is not NULL, the
+.I struct rusage
+to which it points will be filled with accounting information
+about the child.
+See
+.BR getrusage (2)
+for details.
+.SH RETURN VALUE
+As for
+.BR waitpid (2).
+.SH ERRORS
+As for
+.BR waitpid (2).
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD.
+.P
+SUSv1 included a specification of
+.BR wait3 ();
+SUSv2 included
+.BR wait3 (),
+but marked it LEGACY;
+SUSv3 removed it.
+.P
+Including
+.I <sys/time.h>
+is not required these days, but increases portability.
+(Indeed,
+.I <sys/resource.h>
+defines the
+.I rusage
+structure with fields of type
+.I struct timeval
+defined in
+.IR <sys/time.h> .)
+.SS C library/kernel differences
+On Linux,
+.BR wait3 ()
+is a library function implemented on top of the
+.BR wait4 ()
+system call.
+.SH SEE ALSO
+.BR fork (2),
+.BR getrusage (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR wait (2),
+.BR signal (7)
diff --git a/man/man2/waitid.2 b/man/man2/waitid.2
new file mode 100644
index 000000000..0605b3543
--- /dev/null
+++ b/man/man2/waitid.2
@@ -0,0 +1 @@
+.so man2/wait.2
diff --git a/man/man2/waitpid.2 b/man/man2/waitpid.2
new file mode 100644
index 000000000..0605b3543
--- /dev/null
+++ b/man/man2/waitpid.2
@@ -0,0 +1 @@
+.so man2/wait.2
diff --git a/man/man2/write.2 b/man/man2/write.2
new file mode 100644
index 000000000..a24cbdc31
--- /dev/null
+++ b/man/man2/write.2
@@ -0,0 +1,329 @@
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Michael Haardt, Ian Jackson.
+.\" and Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 13:35:59 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Nov 28 17:19:01 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sat Jan 13 12:58:08 1996 by Michael Haardt
+.\"   <michael@cantor.informatik.rwth-aachen.de>
+.\" Modified Sun Jul 21 18:59:33 1996 by Andries Brouwer <aeb@cwi.nl>
+.\" 2001-12-13 added remark by Zack Weinberg
+.\" 2007-06-18 mtk:
+.\"    	Added details about seekable files and file offset.
+.\"	Noted that write() may write less than 'count' bytes, and
+.\"	gave some examples of why this might occur.
+.\"	Noted what happens if write() is interrupted by a signal.
+.\"
+.TH write 2 (date) "Linux man-pages (unreleased)"
+.SH NAME
+write \- write to a file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "ssize_t write(int " fd ", const void " buf [. count "], size_t " count );
+.fi
+.SH DESCRIPTION
+.BR write ()
+writes up to
+.I count
+bytes from the buffer starting at
+.I buf
+to the file referred to by the file descriptor
+.IR fd .
+.P
+The number of bytes written may be less than
+.I count
+if, for example,
+there is insufficient space on the underlying physical medium, or the
+.B RLIMIT_FSIZE
+resource limit is encountered (see
+.BR setrlimit (2)),
+or the call was interrupted by a signal
+handler after having written less than
+.I count
+bytes.
+(See also
+.BR pipe (7).)
+.P
+For a seekable file (i.e., one to which
+.BR lseek (2)
+may be applied, for example, a regular file)
+writing takes place at the file offset,
+and the file offset is incremented by
+the number of bytes actually written.
+If the file was
+.BR open (2)ed
+with
+.BR O_APPEND ,
+the file offset is first set to the end of the file before writing.
+The adjustment of the file offset and the write operation
+are performed as an atomic step.
+.P
+POSIX requires that a
+.BR read (2)
+that can be proved to occur after a
+.BR write ()
+has returned will return the new data.
+Note that not all filesystems are POSIX conforming.
+.P
+According to POSIX.1, if
+.I count
+is greater than
+.BR SSIZE_MAX ,
+the result is implementation-defined;
+see NOTES for the upper limit on Linux.
+.SH RETURN VALUE
+On success, the number of bytes written is returned.
+On error, \-1 is returned, and \fIerrno\fP is set
+to indicate the error.
+.P
+Note that a successful
+.BR write ()
+may transfer fewer than
+.I count
+bytes.
+Such partial writes can occur for various reasons;
+for example, because there was insufficient space on the disk device
+to write all of the requested bytes, or because a blocked
+.BR write ()
+to a socket, pipe, or similar was interrupted by a signal handler
+after it had transferred some, but before it had transferred all
+of the requested bytes.
+In the event of a partial write, the caller can make another
+.BR write ()
+call to transfer the remaining bytes.
+The subsequent call will either transfer further bytes or
+may result in an error (e.g., if the disk is now full).
+.P
+If \fIcount\fP is zero and
+.I fd
+refers to a regular file, then
+.BR write ()
+may return a failure status if one of the errors below is detected.
+If no errors are detected, or error detection is not performed,
+0 is returned without causing any other effect.
+If
+\fIcount\fP is zero and
+.I fd
+refers to a file other than a regular file,
+the results are not specified.
+.SH ERRORS
+.TP
+.B EAGAIN
+The file descriptor
+.I fd
+refers to a file other than a socket and has been marked nonblocking
+.RB ( O_NONBLOCK ),
+and the write would block.
+See
+.BR open (2)
+for further details on the
+.B O_NONBLOCK
+flag.
+.TP
+.BR EAGAIN " or " EWOULDBLOCK
+.\" Actually EAGAIN on Linux
+The file descriptor
+.I fd
+refers to a socket and has been marked nonblocking
+.RB ( O_NONBLOCK ),
+and the write would block.
+POSIX.1-2001 allows either error to be returned for this case,
+and does not require these constants to have the same value,
+so a portable application should check for both possibilities.
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor or is not open for writing.
+.TP
+.B EDESTADDRREQ
+.I fd
+refers to a datagram socket for which a peer address has not been set using
+.BR connect (2).
+.TP
+.B EDQUOT
+The user's quota of disk blocks on the filesystem containing the file
+referred to by
+.I fd
+has been exhausted.
+.TP
+.B EFAULT
+.I buf
+is outside your accessible address space.
+.TP
+.B EFBIG
+An attempt was made to write a file that exceeds the implementation-defined
+maximum file size or the process's file size limit,
+or to write at a position past the maximum allowed offset.
+.TP
+.B EINTR
+The call was interrupted by a signal before any data was written; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I fd
+is attached to an object which is unsuitable for writing;
+or the file was opened with the
+.B O_DIRECT
+flag, and either the address specified in
+.IR buf ,
+the value specified in
+.IR count ,
+or the file offset is not suitably aligned.
+.TP
+.B EIO
+A low-level I/O error occurred while modifying the inode.
+This error may relate to the write-back of data written by an earlier
+.BR write (),
+which may have been issued to a different file descriptor on
+the same file.
+Since Linux 4.13, errors from write-back come
+with a promise that they
+.I may
+be reported by subsequent.
+.BR write ()
+requests, and
+.I will
+be reported by a subsequent
+.BR fsync (2)
+(whether or not they were also reported by
+.BR write ()).
+.\" commit 088737f44bbf6378745f5b57b035e57ee3dc4750
+An alternate cause of
+.B EIO
+on networked filesystems is when an advisory lock had been taken out
+on the file descriptor and this lock has been lost.
+See the
+.I "Lost locks"
+section of
+.BR fcntl (2)
+for further details.
+.TP
+.B ENOSPC
+The device containing the file referred to by
+.I fd
+has no room for the data.
+.TP
+.B EPERM
+The operation was prevented by a file seal; see
+.BR fcntl (2).
+.TP
+.B EPIPE
+.I fd
+is connected to a pipe or socket whose reading end is closed.
+When this happens the writing process will also receive a
+.B SIGPIPE
+signal.
+(Thus, the write return value is seen only if the program
+catches, blocks or ignores this signal.)
+.P
+Other errors may occur, depending on the object connected to
+.IR fd .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+SVr4, 4.3BSD, POSIX.1-2001.
+.\" SVr4 documents additional error
+.\" conditions EDEADLK, ENOLCK, ENOLNK, ENOSR, ENXIO, or ERANGE.
+.P
+Under SVr4 a write may be interrupted and return
+.B EINTR
+at any point,
+not just before any data is written.
+.SH NOTES
+A successful return from
+.BR write ()
+does not make any guarantee that data has been committed to disk.
+On some filesystems, including NFS, it does not even guarantee
+that space has successfully been reserved for the data.
+In this case,
+some errors might be delayed until a future
+.BR write (),
+.BR fsync (2),
+or even
+.BR close (2).
+The only way to be sure is to call
+.BR fsync (2)
+after you are done writing all your data.
+.P
+If a
+.BR write ()
+is interrupted by a signal handler before any bytes are written,
+then the call fails with the error
+.BR EINTR ;
+if it is interrupted after at least one byte has been written,
+the call succeeds, and returns the number of bytes written.
+.P
+On Linux,
+.BR write ()
+(and similar system calls) will transfer at most
+0x7ffff000 (2,147,479,552) bytes,
+returning the number of bytes actually transferred.
+.\" commit e28cc71572da38a5a12c1cfe4d7032017adccf69
+(This is true on both 32-bit and 64-bit systems.)
+.P
+An error return value while performing
+.BR write ()
+using direct I/O does not mean the
+entire write has failed.
+Partial data may be written
+and the data at the file offset on which the
+.BR write ()
+was attempted should be considered inconsistent.
+.SH BUGS
+According to POSIX.1-2008/SUSv4 Section XSI 2.9.7
+("Thread Interactions with Regular File Operations"):
+.P
+.RS 4
+All of the following functions shall be atomic with respect to
+each other in the effects specified in POSIX.1-2008 when they
+operate on regular files or symbolic links: ...
+.RE
+.P
+Among the APIs subsequently listed are
+.BR write ()
+and
+.BR writev (2).
+And among the effects that should be atomic across threads (and processes)
+are updates of the file offset.
+However, before Linux 3.14,
+this was not the case: if two processes that share
+an open file description (see
+.BR open (2))
+perform a
+.BR write ()
+(or
+.BR writev (2))
+at the same time, then the I/O operations were not atomic
+with respect to updating the file offset,
+with the result that the blocks of data output by the two processes
+might (incorrectly) overlap.
+This problem was fixed in Linux 3.14.
+.\" http://thread.gmane.org/gmane.linux.kernel/1649458
+.\"    From: Michael Kerrisk (man-pages <mtk.manpages <at> gmail.com>
+.\"    Subject: Update of file offset on write() etc. is non-atomic with I/O
+.\"    Date: 2014-02-17 15:41:37 GMT
+.\"    Newsgroups: gmane.linux.kernel, gmane.linux.file-systems
+.\" commit 9c225f2655e36a470c4f58dbbc99244c5fc7f2d4
+.\"    Author: Linus Torvalds <torvalds@linux-foundation.org>
+.\"    Date:   Mon Mar 3 09:36:58 2014 -0800
+.\"
+.\"        vfs: atomic f_pos accesses as per POSIX
+.SH SEE ALSO
+.BR close (2),
+.BR fcntl (2),
+.BR fsync (2),
+.BR ioctl (2),
+.BR lseek (2),
+.BR open (2),
+.BR pwrite (2),
+.BR read (2),
+.BR select (2),
+.BR writev (2),
+.BR fwrite (3)
diff --git a/man/man2/writev.2 b/man/man2/writev.2
new file mode 100644
index 000000000..54e3384ef
--- /dev/null
+++ b/man/man2/writev.2
@@ -0,0 +1 @@
+.so man2/readv.2
diff --git a/man/man2type/open_how.2type b/man/man2type/open_how.2type
new file mode 100644
index 000000000..54da1f9ff
--- /dev/null
+++ b/man/man2type/open_how.2type
@@ -0,0 +1,51 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH open_how 2type (date) "Linux man-pages (unreleased)"
+.SH NAME
+open_how \- how to open a pathname
+.SH LIBRARY
+Linux kernel headers
+.SH SYNOPSIS
+.EX
+.B #include <linux/openat2.h>
+.P
+.B struct open_how {
+.BR "    u64  flags;" "    /* " O_ "* flags */"
+.BR "    u64  mode;" "     /* Mode for " O_ { CREAT , TMPFILE "} */"
+.BR "    u64  resolve;" "  /* " RESOLVE_ "* flags */"
+    /* ... */
+.B };
+.EE
+.SH DESCRIPTION
+Specifies how a pathname should be opened.
+.P
+The fields are as follows:
+.TP
+.I flags
+This field specifies the file creation and file status flags
+to use when opening the file.
+.TP
+.I mode
+This field specifies the mode for the new file.
+.TP
+.I resolve
+This is a bit mask of flags that modify the way in which
+.I all
+components of a pathname will be resolved
+(see
+.BR path_resolution (7)
+for background information).
+.SH VERSIONS
+Extra fields may be appended to the structure,
+with a zero value in a new field resulting in
+the kernel behaving as though that extension field was not present.
+Therefore, a user
+.I must
+zero-fill this structure on initialization.
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR openat2 (2)
diff --git a/man/man3/CIRCLEQ_EMPTY.3 b/man/man3/CIRCLEQ_EMPTY.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_EMPTY.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_ENTRY.3 b/man/man3/CIRCLEQ_ENTRY.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_ENTRY.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_FIRST.3 b/man/man3/CIRCLEQ_FIRST.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_FIRST.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_FOREACH.3 b/man/man3/CIRCLEQ_FOREACH.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_FOREACH.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_FOREACH_REVERSE.3 b/man/man3/CIRCLEQ_FOREACH_REVERSE.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_FOREACH_REVERSE.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_HEAD.3 b/man/man3/CIRCLEQ_HEAD.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_HEAD.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_HEAD_INITIALIZER.3 b/man/man3/CIRCLEQ_HEAD_INITIALIZER.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_HEAD_INITIALIZER.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_INIT.3 b/man/man3/CIRCLEQ_INIT.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_INIT.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_INSERT_AFTER.3 b/man/man3/CIRCLEQ_INSERT_AFTER.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_INSERT_AFTER.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_INSERT_BEFORE.3 b/man/man3/CIRCLEQ_INSERT_BEFORE.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_INSERT_BEFORE.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_INSERT_HEAD.3 b/man/man3/CIRCLEQ_INSERT_HEAD.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_INSERT_HEAD.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_INSERT_TAIL.3 b/man/man3/CIRCLEQ_INSERT_TAIL.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_INSERT_TAIL.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_LAST.3 b/man/man3/CIRCLEQ_LAST.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_LAST.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_LOOP_NEXT.3 b/man/man3/CIRCLEQ_LOOP_NEXT.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_LOOP_NEXT.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_LOOP_PREV.3 b/man/man3/CIRCLEQ_LOOP_PREV.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_LOOP_PREV.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_NEXT.3 b/man/man3/CIRCLEQ_NEXT.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_NEXT.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_PREV.3 b/man/man3/CIRCLEQ_PREV.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_PREV.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CIRCLEQ_REMOVE.3 b/man/man3/CIRCLEQ_REMOVE.3
new file mode 100644
index 000000000..ed0fc9a3b
--- /dev/null
+++ b/man/man3/CIRCLEQ_REMOVE.3
@@ -0,0 +1 @@
+.so man3/circleq.3
diff --git a/man/man3/CMSG_ALIGN.3 b/man/man3/CMSG_ALIGN.3
new file mode 100644
index 000000000..ad67f433f
--- /dev/null
+++ b/man/man3/CMSG_ALIGN.3
@@ -0,0 +1 @@
+.so man3/cmsg.3
diff --git a/man/man3/CMSG_DATA.3 b/man/man3/CMSG_DATA.3
new file mode 100644
index 000000000..ad67f433f
--- /dev/null
+++ b/man/man3/CMSG_DATA.3
@@ -0,0 +1 @@
+.so man3/cmsg.3
diff --git a/man/man3/CMSG_FIRSTHDR.3 b/man/man3/CMSG_FIRSTHDR.3
new file mode 100644
index 000000000..ad67f433f
--- /dev/null
+++ b/man/man3/CMSG_FIRSTHDR.3
@@ -0,0 +1 @@
+.so man3/cmsg.3
diff --git a/man/man3/CMSG_LEN.3 b/man/man3/CMSG_LEN.3
new file mode 100644
index 000000000..ad67f433f
--- /dev/null
+++ b/man/man3/CMSG_LEN.3
@@ -0,0 +1 @@
+.so man3/cmsg.3
diff --git a/man/man3/CMSG_NXTHDR.3 b/man/man3/CMSG_NXTHDR.3
new file mode 100644
index 000000000..ad67f433f
--- /dev/null
+++ b/man/man3/CMSG_NXTHDR.3
@@ -0,0 +1 @@
+.so man3/cmsg.3
diff --git a/man/man3/CMSG_SPACE.3 b/man/man3/CMSG_SPACE.3
new file mode 100644
index 000000000..ad67f433f
--- /dev/null
+++ b/man/man3/CMSG_SPACE.3
@@ -0,0 +1 @@
+.so man3/cmsg.3
diff --git a/man/man3/CPU_ALLOC.3 b/man/man3/CPU_ALLOC.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_ALLOC.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_ALLOC_SIZE.3 b/man/man3/CPU_ALLOC_SIZE.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_ALLOC_SIZE.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_AND.3 b/man/man3/CPU_AND.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_AND.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_AND_S.3 b/man/man3/CPU_AND_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_AND_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_CLR.3 b/man/man3/CPU_CLR.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_CLR.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_CLR_S.3 b/man/man3/CPU_CLR_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_CLR_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_COUNT.3 b/man/man3/CPU_COUNT.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_COUNT.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_COUNT_S.3 b/man/man3/CPU_COUNT_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_COUNT_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_EQUAL.3 b/man/man3/CPU_EQUAL.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_EQUAL.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_EQUAL_S.3 b/man/man3/CPU_EQUAL_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_EQUAL_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_FREE.3 b/man/man3/CPU_FREE.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_FREE.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_ISSET.3 b/man/man3/CPU_ISSET.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_ISSET.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_ISSET_S.3 b/man/man3/CPU_ISSET_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_ISSET_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_OR.3 b/man/man3/CPU_OR.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_OR.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_OR_S.3 b/man/man3/CPU_OR_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_OR_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_SET.3 b/man/man3/CPU_SET.3
new file mode 100644
index 000000000..402910913
--- /dev/null
+++ b/man/man3/CPU_SET.3
@@ -0,0 +1,348 @@
+.\" Copyright (C) 2006 Michael Kerrisk
+.\" and Copyright (C) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH CPU_SET 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+CPU_SET, CPU_CLR, CPU_ISSET, CPU_ZERO, CPU_COUNT,
+CPU_AND, CPU_OR, CPU_XOR, CPU_EQUAL,
+CPU_ALLOC, CPU_ALLOC_SIZE, CPU_FREE,
+CPU_SET_S, CPU_CLR_S, CPU_ISSET_S, CPU_ZERO_S,
+CPU_COUNT_S, CPU_AND_S, CPU_OR_S, CPU_XOR_S, CPU_EQUAL_S \-
+macros for manipulating CPU sets
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sched.h>
+.P
+.BI "void CPU_ZERO(cpu_set_t *" set );
+.P
+.BI "void CPU_SET(int " cpu ", cpu_set_t *" set );
+.BI "void CPU_CLR(int " cpu ", cpu_set_t *" set );
+.BI "int  CPU_ISSET(int " cpu ", cpu_set_t *" set );
+.P
+.BI "int  CPU_COUNT(cpu_set_t *" set );
+.P
+.BI "void CPU_AND(cpu_set_t *" destset ,
+.BI "             cpu_set_t *" srcset1 ", cpu_set_t *" srcset2 );
+.BI "void CPU_OR(cpu_set_t *" destset ,
+.BI "             cpu_set_t *" srcset1 ", cpu_set_t *" srcset2 );
+.BI "void CPU_XOR(cpu_set_t *" destset ,
+.BI "             cpu_set_t *" srcset1 ", cpu_set_t *" srcset2 );
+.P
+.BI "int  CPU_EQUAL(cpu_set_t *" set1 ", cpu_set_t *" set2 );
+.P
+.BI "cpu_set_t *CPU_ALLOC(int " num_cpus );
+.BI "void CPU_FREE(cpu_set_t *" set );
+.BI "size_t CPU_ALLOC_SIZE(int " num_cpus );
+.P
+.BI "void CPU_ZERO_S(size_t " setsize ", cpu_set_t *" set );
+.P
+.BI "void CPU_SET_S(int " cpu ", size_t " setsize ", cpu_set_t *" set );
+.BI "void CPU_CLR_S(int " cpu ", size_t " setsize ", cpu_set_t *" set );
+.BI "int  CPU_ISSET_S(int " cpu ", size_t " setsize ", cpu_set_t *" set );
+.P
+.BI "int  CPU_COUNT_S(size_t " setsize ", cpu_set_t *" set );
+.P
+.BI "void CPU_AND_S(size_t " setsize ", cpu_set_t *" destset ,
+.BI "             cpu_set_t *" srcset1 ", cpu_set_t *" srcset2 );
+.BI "void CPU_OR_S(size_t " setsize ", cpu_set_t *" destset ,
+.BI "             cpu_set_t *" srcset1 ", cpu_set_t *" srcset2 );
+.BI "void CPU_XOR_S(size_t " setsize ", cpu_set_t *" destset ,
+.BI "             cpu_set_t *" srcset1 ", cpu_set_t *" srcset2 );
+.P
+.BI "int  CPU_EQUAL_S(size_t " setsize ", cpu_set_t *" set1 \
+", cpu_set_t *" set2 );
+.fi
+.SH DESCRIPTION
+The
+.I cpu_set_t
+data structure represents a set of CPUs.
+CPU sets are used by
+.BR sched_setaffinity (2)
+and similar interfaces.
+.P
+The
+.I cpu_set_t
+data type is implemented as a bit mask.
+However, the data structure should be treated as opaque:
+all manipulation of CPU sets should be done via the macros
+described in this page.
+.P
+The following macros are provided to operate on the CPU set
+.IR set :
+.TP
+.BR CPU_ZERO ()
+Clears
+.IR set ,
+so that it contains no CPUs.
+.TP
+.BR CPU_SET ()
+Add CPU
+.I cpu
+to
+.IR set .
+.TP
+.BR CPU_CLR ()
+Remove CPU
+.I cpu
+from
+.IR set .
+.TP
+.BR CPU_ISSET ()
+Test to see if CPU
+.I cpu
+is a member of
+.IR set .
+.TP
+.BR CPU_COUNT ()
+Return the number of CPUs in
+.IR set .
+.P
+Where a
+.I cpu
+argument is specified, it should not produce side effects,
+since the above macros may evaluate the argument more than once.
+.P
+The first CPU on the system corresponds to a
+.I cpu
+value of 0, the next CPU corresponds to a
+.I cpu
+value of 1, and so on.
+No assumptions should be made about particular CPUs being
+available, or the set of CPUs being contiguous, since CPUs can
+be taken offline dynamically or be otherwise absent.
+The constant
+.B CPU_SETSIZE
+(currently 1024) specifies a value one greater than the maximum CPU
+number that can be stored in
+.IR cpu_set_t .
+.P
+The following macros perform logical operations on CPU sets:
+.TP
+.BR CPU_AND ()
+Store the intersection of the sets
+.I srcset1
+and
+.I srcset2
+in
+.I destset
+(which may be one of the source sets).
+.TP
+.BR CPU_OR ()
+Store the union of the sets
+.I srcset1
+and
+.I srcset2
+in
+.I destset
+(which may be one of the source sets).
+.TP
+.BR CPU_XOR ()
+Store the XOR of the sets
+.I srcset1
+and
+.I srcset2
+in
+.I destset
+(which may be one of the source sets).
+The XOR means the set of CPUs that are in either
+.I srcset1
+or
+.IR srcset2 ,
+but not both.
+.TP
+.BR CPU_EQUAL ()
+Test whether two CPU set contain exactly the same CPUs.
+.SS Dynamically sized CPU sets
+Because some applications may require the ability to dynamically
+size CPU sets (e.g., to allocate sets larger than that
+defined by the standard
+.I cpu_set_t
+data type), glibc nowadays provides a set of macros to support this.
+.P
+The following macros are used to allocate and deallocate CPU sets:
+.TP
+.BR CPU_ALLOC ()
+Allocate a CPU set large enough to hold CPUs
+in the range 0 to
+.IR num_cpus\-1 .
+.TP
+.BR CPU_ALLOC_SIZE ()
+Return the size in bytes of the CPU set that would be needed to
+hold CPUs in the range 0 to
+.IR num_cpus\-1 .
+This macro provides the value that can be used for the
+.I setsize
+argument in the
+.BR CPU_*_S ()
+macros described below.
+.TP
+.BR CPU_FREE ()
+Free a CPU set previously allocated by
+.BR CPU_ALLOC ().
+.P
+The macros whose names end with "_S" are the analogs of
+the similarly named macros without the suffix.
+These macros perform the same tasks as their analogs,
+but operate on the dynamically allocated CPU set(s) whose size is
+.I setsize
+bytes.
+.SH RETURN VALUE
+.BR CPU_ISSET ()
+and
+.BR CPU_ISSET_S ()
+return nonzero if
+.I cpu
+is in
+.IR set ;
+otherwise, it returns 0.
+.P
+.BR CPU_COUNT ()
+and
+.BR CPU_COUNT_S ()
+return the number of CPUs in
+.IR set .
+.P
+.BR CPU_EQUAL ()
+and
+.BR CPU_EQUAL_S ()
+return nonzero if the two CPU sets are equal; otherwise they return 0.
+.P
+.BR CPU_ALLOC ()
+returns a pointer on success, or NULL on failure.
+(Errors are as for
+.BR malloc (3).)
+.P
+.BR CPU_ALLOC_SIZE ()
+returns the number of bytes required to store a
+CPU set of the specified cardinality.
+.P
+The other functions do not return a value.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+The
+.BR CPU_ZERO (),
+.BR CPU_SET (),
+.BR CPU_CLR (),
+and
+.BR CPU_ISSET ()
+macros were added in glibc 2.3.3.
+.P
+.BR CPU_COUNT ()
+first appeared in glibc 2.6.
+.P
+.BR CPU_AND (),
+.BR CPU_OR (),
+.BR CPU_XOR (),
+.BR CPU_EQUAL (),
+.BR CPU_ALLOC (),
+.BR CPU_ALLOC_SIZE (),
+.BR CPU_FREE (),
+.BR CPU_ZERO_S (),
+.BR CPU_SET_S (),
+.BR CPU_CLR_S (),
+.BR CPU_ISSET_S (),
+.BR CPU_AND_S (),
+.BR CPU_OR_S (),
+.BR CPU_XOR_S (),
+and
+.BR CPU_EQUAL_S ()
+first appeared in glibc 2.7.
+.SH NOTES
+To duplicate a CPU set, use
+.BR memcpy (3).
+.P
+Since CPU sets are bit masks allocated in units of long words,
+the actual number of CPUs in a dynamically
+allocated CPU set will be rounded up to the next multiple of
+.IR "sizeof(unsigned long)" .
+An application should consider the contents of these extra bits
+to be undefined.
+.P
+Notwithstanding the similarity in the names,
+note that the constant
+.B CPU_SETSIZE
+indicates the number of CPUs in the
+.I cpu_set_t
+data type (thus, it is effectively a count of the bits in the bit mask),
+while the
+.I setsize
+argument of the
+.BR CPU_*_S ()
+macros is a size in bytes.
+.P
+The data types for arguments and return values shown
+in the SYNOPSIS are hints what about is expected in each case.
+However, since these interfaces are implemented as macros,
+the compiler won't necessarily catch all type errors
+if you violate the suggestions.
+.SH BUGS
+On 32-bit platforms with glibc 2.8 and earlier,
+.BR CPU_ALLOC ()
+allocates twice as much space as is required, and
+.BR CPU_ALLOC_SIZE ()
+returns a value twice as large as it should.
+This bug should not affect the semantics of a program,
+but does result in wasted memory
+and less efficient operation of the macros that
+operate on dynamically allocated CPU sets.
+These bugs are fixed in glibc 2.9.
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=7029
+.SH EXAMPLES
+The following program demonstrates the use of some of the macros
+used for dynamically allocated CPU sets.
+.P
+.\" SRC BEGIN (CPU_SET.c)
+.EX
+#define _GNU_SOURCE
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#include <assert.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    cpu_set_t *cpusetp;
+    size_t size, num_cpus;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <num\-cpus>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    num_cpus = atoi(argv[1]);
+\&
+    cpusetp = CPU_ALLOC(num_cpus);
+    if (cpusetp == NULL) {
+        perror("CPU_ALLOC");
+        exit(EXIT_FAILURE);
+    }
+\&
+    size = CPU_ALLOC_SIZE(num_cpus);
+\&
+    CPU_ZERO_S(size, cpusetp);
+    for (size_t cpu = 0; cpu < num_cpus; cpu += 2)
+        CPU_SET_S(cpu, size, cpusetp);
+\&
+    printf("CPU_COUNT() of set:    %d\en", CPU_COUNT_S(size, cpusetp));
+\&
+    CPU_FREE(cpusetp);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR sched_setaffinity (2),
+.BR pthread_attr_setaffinity_np (3),
+.BR pthread_setaffinity_np (3),
+.BR cpuset (7)
diff --git a/man/man3/CPU_SET_S.3 b/man/man3/CPU_SET_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_SET_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_XOR.3 b/man/man3/CPU_XOR.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_XOR.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_XOR_S.3 b/man/man3/CPU_XOR_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_XOR_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_ZERO.3 b/man/man3/CPU_ZERO.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_ZERO.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/CPU_ZERO_S.3 b/man/man3/CPU_ZERO_S.3
new file mode 100644
index 000000000..cdc74d479
--- /dev/null
+++ b/man/man3/CPU_ZERO_S.3
@@ -0,0 +1 @@
+.so man3/CPU_SET.3
diff --git a/man/man3/DES_FAILED.3 b/man/man3/DES_FAILED.3
new file mode 100644
index 000000000..853c9cbdf
--- /dev/null
+++ b/man/man3/DES_FAILED.3
@@ -0,0 +1 @@
+.so man3/des_crypt.3
diff --git a/man/man3/FD_CLR.3 b/man/man3/FD_CLR.3
new file mode 100644
index 000000000..e17784318
--- /dev/null
+++ b/man/man3/FD_CLR.3
@@ -0,0 +1 @@
+.so man2/select.2
diff --git a/man/man3/FD_ISSET.3 b/man/man3/FD_ISSET.3
new file mode 100644
index 000000000..e17784318
--- /dev/null
+++ b/man/man3/FD_ISSET.3
@@ -0,0 +1 @@
+.so man2/select.2
diff --git a/man/man3/FD_SET.3 b/man/man3/FD_SET.3
new file mode 100644
index 000000000..e17784318
--- /dev/null
+++ b/man/man3/FD_SET.3
@@ -0,0 +1 @@
+.so man2/select.2
diff --git a/man/man3/FD_ZERO.3 b/man/man3/FD_ZERO.3
new file mode 100644
index 000000000..e17784318
--- /dev/null
+++ b/man/man3/FD_ZERO.3
@@ -0,0 +1 @@
+.so man2/select.2
diff --git a/man/man3/HUGE_VAL.3 b/man/man3/HUGE_VAL.3
new file mode 100644
index 000000000..dd04d2c5c
--- /dev/null
+++ b/man/man3/HUGE_VAL.3
@@ -0,0 +1 @@
+.so man3/INFINITY.3
diff --git a/man/man3/HUGE_VALF.3 b/man/man3/HUGE_VALF.3
new file mode 100644
index 000000000..dd04d2c5c
--- /dev/null
+++ b/man/man3/HUGE_VALF.3
@@ -0,0 +1 @@
+.so man3/INFINITY.3
diff --git a/man/man3/HUGE_VALL.3 b/man/man3/HUGE_VALL.3
new file mode 100644
index 000000000..dd04d2c5c
--- /dev/null
+++ b/man/man3/HUGE_VALL.3
@@ -0,0 +1 @@
+.so man3/INFINITY.3
diff --git a/man/man3/INFINITY.3 b/man/man3/INFINITY.3
new file mode 100644
index 000000000..f67be82c8
--- /dev/null
+++ b/man/man3/INFINITY.3
@@ -0,0 +1,85 @@
+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH INFINITY 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+INFINITY, NAN, HUGE_VAL, HUGE_VALF, HUGE_VALL \- floating-point constants
+.SH LIBRARY
+Math library
+.RI ( libm )
+.SH SYNOPSIS
+.nf
+.BR "#define _ISOC99_SOURCE" "      /* See feature_test_macros(7) */"
+.B #include <math.h>
+.P
+.B INFINITY
+.P
+.B NAN
+.P
+.B HUGE_VAL
+.B HUGE_VALF
+.B HUGE_VALL
+.fi
+.SH DESCRIPTION
+The macro
+.B INFINITY
+expands to a
+.I float
+constant representing positive infinity.
+.P
+The macro
+.B NAN
+expands to a
+.I float
+constant representing a quiet NaN
+(when supported).
+A
+.I quiet
+NaN is a NaN ("not-a-number") that does not raise exceptions
+when it is used in arithmetic.
+The opposite is a
+.I signaling
+NaN.
+See IEC 60559:1989.
+.P
+The macros
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+.B HUGE_VALL
+expand to constants of types
+.IR double ,
+.IR float ,
+and
+.IR "long double" ,
+respectively,
+that represent a large positive value, possibly positive infinity.
+.SH STANDARDS
+C11.
+.SH HISTORY
+C99.
+.P
+On a glibc system, the macro
+.B HUGE_VAL
+is always available.
+Availability of the
+.B NAN
+macro can be tested using
+.BR "#ifdef NAN" ,
+and similarly for
+.BR INFINITY ,
+.BR HUGE_VALF ,
+.BR HUGE_VALL .
+They will be defined by
+.I <math.h>
+if
+.B _ISOC99_SOURCE
+or
+.B _GNU_SOURCE
+is defined, or
+.B __STDC_VERSION__
+is defined
+and has a value not less than 199901L.
+.SH SEE ALSO
+.BR fpclassify (3),
+.BR math_error (7)
diff --git a/man/man3/LIST_EMPTY.3 b/man/man3/LIST_EMPTY.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_EMPTY.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_ENTRY.3 b/man/man3/LIST_ENTRY.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_ENTRY.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_FIRST.3 b/man/man3/LIST_FIRST.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_FIRST.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_FOREACH.3 b/man/man3/LIST_FOREACH.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_FOREACH.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_HEAD.3 b/man/man3/LIST_HEAD.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_HEAD.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_HEAD_INITIALIZER.3 b/man/man3/LIST_HEAD_INITIALIZER.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_HEAD_INITIALIZER.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_INIT.3 b/man/man3/LIST_INIT.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_INIT.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_INSERT_AFTER.3 b/man/man3/LIST_INSERT_AFTER.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_INSERT_AFTER.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_INSERT_BEFORE.3 b/man/man3/LIST_INSERT_BEFORE.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_INSERT_BEFORE.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_INSERT_HEAD.3 b/man/man3/LIST_INSERT_HEAD.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_INSERT_HEAD.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_NEXT.3 b/man/man3/LIST_NEXT.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_NEXT.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/LIST_REMOVE.3 b/man/man3/LIST_REMOVE.3
new file mode 100644
index 000000000..dfafea85d
--- /dev/null
+++ b/man/man3/LIST_REMOVE.3
@@ -0,0 +1 @@
+.so man3/list.3
diff --git a/man/man3/MAX.3 b/man/man3/MAX.3
new file mode 100644
index 000000000..9e74ad614
--- /dev/null
+++ b/man/man3/MAX.3
@@ -0,0 +1,75 @@
+.\" Copyright (C) 2021 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH MAX 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+MAX, MIN \- maximum or minimum of two values
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/param.h>
+.P
+.BI MAX( a ", " b );
+.BI MIN( a ", " b );
+.fi
+.SH DESCRIPTION
+These macros return the maximum or minimum of
+.I a
+and
+.IR b .
+.SH RETURN VALUE
+These macros return the value of one of their arguments,
+possibly converted to a different type (see BUGS).
+.SH ERRORS
+These macros may raise the "invalid" floating-point exception
+when any of the arguments is NaN.
+.SH STANDARDS
+GNU, BSD.
+.SH NOTES
+If either of the arguments is of a floating-point type,
+you might prefer to use
+.BR fmax (3)
+or
+.BR fmin (3),
+which can handle NaN.
+.P
+The arguments may be evaluated more than once, or not at all.
+.P
+Some UNIX systems might provide these macros in a different header,
+or not at all.
+.SH BUGS
+Due to the usual arithmetic conversions,
+the result of these macros may be very different from either of the arguments.
+To avoid this, ensure that both arguments have the same type.
+.SH EXAMPLES
+.\" SRC BEGIN (MAX.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/param.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int a, b, x;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <num> <num>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    a = atoi(argv[1]);
+    b = atoi(argv[2]);
+    x = MAX(a, b);
+    printf("MAX(%d, %d) is %d\en", a, b, x);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fmax (3),
+.BR fmin (3)
diff --git a/man/man3/MB_CUR_MAX.3 b/man/man3/MB_CUR_MAX.3
new file mode 100644
index 000000000..a1cb3046f
--- /dev/null
+++ b/man/man3/MB_CUR_MAX.3
@@ -0,0 +1,43 @@
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.\" Modified, aeb, 990824
+.\"
+.TH MB_CUR_MAX 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+MB_CUR_MAX \- maximum length of a multibyte character in the current locale
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.fi
+.SH DESCRIPTION
+The
+.B MB_CUR_MAX
+macro defines an integer expression giving
+the maximum number of bytes needed to represent a single
+wide character in the current locale.
+This value is locale dependent and therefore not a compile-time constant.
+.SH RETURN VALUE
+An integer in the range [1,
+.BR MB_LEN_MAX ].
+The value 1 denotes traditional 8-bit encoded characters.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR MB_LEN_MAX (3),
+.BR mblen (3),
+.BR mbstowcs (3),
+.BR mbtowc (3),
+.BR wcstombs (3),
+.BR wctomb (3)
diff --git a/man/man3/MB_LEN_MAX.3 b/man/man3/MB_LEN_MAX.3
new file mode 100644
index 000000000..c28bbb150
--- /dev/null
+++ b/man/man3/MB_LEN_MAX.3
@@ -0,0 +1,51 @@
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.\" Modified, aeb, 990824
+.\"
+.TH MB_LEN_MAX 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+MB_LEN_MAX \- maximum multibyte length of a character across all locales
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <limits.h>
+.fi
+.SH DESCRIPTION
+The
+.B MB_LEN_MAX
+macro is the maximum number of bytes needed to represent a single
+wide character, in any of the supported locales.
+.SH RETURN VALUE
+A constant integer greater than zero.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH NOTES
+The entities
+.B MB_LEN_MAX
+and
+.I sizeof(wchar_t)
+are totally unrelated.
+In glibc,
+.B MB_LEN_MAX
+is typically 16
+.\" For an explanation of why the limit was raised to 16, see
+.\" http://lists.gnu.org/archive/html/bug-gnulib/2015-05/msg00001.html
+.\"     From:    Bruno Haible
+.\"     Subject: Re: why is MB_LEN_MAX so large (16) on glibc
+.\"     Date:    Thu, 14 May 2015 02:30:14 +0200
+(6 in glibc versions earlier than 2.2), while
+.I sizeof(wchar_t)
+is 4.
+.SH SEE ALSO
+.BR MB_CUR_MAX (3)
diff --git a/man/man3/MIN.3 b/man/man3/MIN.3
new file mode 100644
index 000000000..9938abda2
--- /dev/null
+++ b/man/man3/MIN.3
@@ -0,0 +1 @@
+.so man3/MAX.3
diff --git a/man/man3/NAN.3 b/man/man3/NAN.3
new file mode 100644
index 000000000..dd04d2c5c
--- /dev/null
+++ b/man/man3/NAN.3
@@ -0,0 +1 @@
+.so man3/INFINITY.3
diff --git a/man/man3/SIMPLEQ_EMPTY.3 b/man/man3/SIMPLEQ_EMPTY.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_EMPTY.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_ENTRY.3 b/man/man3/SIMPLEQ_ENTRY.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_ENTRY.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_FIRST.3 b/man/man3/SIMPLEQ_FIRST.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_FIRST.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_FOREACH.3 b/man/man3/SIMPLEQ_FOREACH.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_FOREACH.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_HEAD.3 b/man/man3/SIMPLEQ_HEAD.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_HEAD.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_HEAD_INITIALIZER.3 b/man/man3/SIMPLEQ_HEAD_INITIALIZER.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_HEAD_INITIALIZER.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_INIT.3 b/man/man3/SIMPLEQ_INIT.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_INIT.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_INSERT_AFTER.3 b/man/man3/SIMPLEQ_INSERT_AFTER.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_INSERT_AFTER.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_INSERT_HEAD.3 b/man/man3/SIMPLEQ_INSERT_HEAD.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_INSERT_HEAD.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_INSERT_TAIL.3 b/man/man3/SIMPLEQ_INSERT_TAIL.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_INSERT_TAIL.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_NEXT.3 b/man/man3/SIMPLEQ_NEXT.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_NEXT.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_REMOVE.3 b/man/man3/SIMPLEQ_REMOVE.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_REMOVE.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SIMPLEQ_REMOVE_HEAD.3 b/man/man3/SIMPLEQ_REMOVE_HEAD.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/SIMPLEQ_REMOVE_HEAD.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/SLIST_EMPTY.3 b/man/man3/SLIST_EMPTY.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_EMPTY.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_ENTRY.3 b/man/man3/SLIST_ENTRY.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_ENTRY.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_FIRST.3 b/man/man3/SLIST_FIRST.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_FIRST.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_FOREACH.3 b/man/man3/SLIST_FOREACH.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_FOREACH.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_HEAD.3 b/man/man3/SLIST_HEAD.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_HEAD.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_HEAD_INITIALIZER.3 b/man/man3/SLIST_HEAD_INITIALIZER.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_HEAD_INITIALIZER.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_INIT.3 b/man/man3/SLIST_INIT.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_INIT.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_INSERT_AFTER.3 b/man/man3/SLIST_INSERT_AFTER.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_INSERT_AFTER.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_INSERT_HEAD.3 b/man/man3/SLIST_INSERT_HEAD.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_INSERT_HEAD.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_NEXT.3 b/man/man3/SLIST_NEXT.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_NEXT.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_REMOVE.3 b/man/man3/SLIST_REMOVE.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_REMOVE.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/SLIST_REMOVE_HEAD.3 b/man/man3/SLIST_REMOVE_HEAD.3
new file mode 100644
index 000000000..260541bcb
--- /dev/null
+++ b/man/man3/SLIST_REMOVE_HEAD.3
@@ -0,0 +1 @@
+.so man3/slist.3
diff --git a/man/man3/STAILQ_CONCAT.3 b/man/man3/STAILQ_CONCAT.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_CONCAT.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_EMPTY.3 b/man/man3/STAILQ_EMPTY.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_EMPTY.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_ENTRY.3 b/man/man3/STAILQ_ENTRY.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_ENTRY.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_FIRST.3 b/man/man3/STAILQ_FIRST.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_FIRST.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_FOREACH.3 b/man/man3/STAILQ_FOREACH.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_FOREACH.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_HEAD.3 b/man/man3/STAILQ_HEAD.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_HEAD.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_HEAD_INITIALIZER.3 b/man/man3/STAILQ_HEAD_INITIALIZER.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_HEAD_INITIALIZER.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_INIT.3 b/man/man3/STAILQ_INIT.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_INIT.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_INSERT_AFTER.3 b/man/man3/STAILQ_INSERT_AFTER.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_INSERT_AFTER.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_INSERT_HEAD.3 b/man/man3/STAILQ_INSERT_HEAD.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_INSERT_HEAD.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_INSERT_TAIL.3 b/man/man3/STAILQ_INSERT_TAIL.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_INSERT_TAIL.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_NEXT.3 b/man/man3/STAILQ_NEXT.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_NEXT.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_REMOVE.3 b/man/man3/STAILQ_REMOVE.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_REMOVE.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/STAILQ_REMOVE_HEAD.3 b/man/man3/STAILQ_REMOVE_HEAD.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/STAILQ_REMOVE_HEAD.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/S_ISBLK.3 b/man/man3/S_ISBLK.3
new file mode 100644
index 000000000..a5c4b88db
--- /dev/null
+++ b/man/man3/S_ISBLK.3
@@ -0,0 +1 @@
+.so man7/inode.7
diff --git a/man/man3/S_ISCHR.3 b/man/man3/S_ISCHR.3
new file mode 100644
index 000000000..a5c4b88db
--- /dev/null
+++ b/man/man3/S_ISCHR.3
@@ -0,0 +1 @@
+.so man7/inode.7
diff --git a/man/man3/S_ISDIR.3 b/man/man3/S_ISDIR.3
new file mode 100644
index 000000000..a5c4b88db
--- /dev/null
+++ b/man/man3/S_ISDIR.3
@@ -0,0 +1 @@
+.so man7/inode.7
diff --git a/man/man3/S_ISFIFO.3 b/man/man3/S_ISFIFO.3
new file mode 100644
index 000000000..a5c4b88db
--- /dev/null
+++ b/man/man3/S_ISFIFO.3
@@ -0,0 +1 @@
+.so man7/inode.7
diff --git a/man/man3/S_ISLNK.3 b/man/man3/S_ISLNK.3
new file mode 100644
index 000000000..a5c4b88db
--- /dev/null
+++ b/man/man3/S_ISLNK.3
@@ -0,0 +1 @@
+.so man7/inode.7
diff --git a/man/man3/S_ISREG.3 b/man/man3/S_ISREG.3
new file mode 100644
index 000000000..a5c4b88db
--- /dev/null
+++ b/man/man3/S_ISREG.3
@@ -0,0 +1 @@
+.so man7/inode.7
diff --git a/man/man3/S_ISSOCK.3 b/man/man3/S_ISSOCK.3
new file mode 100644
index 000000000..a5c4b88db
--- /dev/null
+++ b/man/man3/S_ISSOCK.3
@@ -0,0 +1 @@
+.so man7/inode.7
diff --git a/man/man3/TAILQ_CONCAT.3 b/man/man3/TAILQ_CONCAT.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_CONCAT.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_EMPTY.3 b/man/man3/TAILQ_EMPTY.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_EMPTY.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_ENTRY.3 b/man/man3/TAILQ_ENTRY.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_ENTRY.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_FIRST.3 b/man/man3/TAILQ_FIRST.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_FIRST.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_FOREACH.3 b/man/man3/TAILQ_FOREACH.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_FOREACH.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_FOREACH_REVERSE.3 b/man/man3/TAILQ_FOREACH_REVERSE.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_FOREACH_REVERSE.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_HEAD.3 b/man/man3/TAILQ_HEAD.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_HEAD.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_HEAD_INITIALIZER.3 b/man/man3/TAILQ_HEAD_INITIALIZER.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_HEAD_INITIALIZER.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_INIT.3 b/man/man3/TAILQ_INIT.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_INIT.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_INSERT_AFTER.3 b/man/man3/TAILQ_INSERT_AFTER.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_INSERT_AFTER.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_INSERT_BEFORE.3 b/man/man3/TAILQ_INSERT_BEFORE.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_INSERT_BEFORE.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_INSERT_HEAD.3 b/man/man3/TAILQ_INSERT_HEAD.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_INSERT_HEAD.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_INSERT_TAIL.3 b/man/man3/TAILQ_INSERT_TAIL.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_INSERT_TAIL.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_LAST.3 b/man/man3/TAILQ_LAST.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_LAST.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_NEXT.3 b/man/man3/TAILQ_NEXT.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_NEXT.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_PREV.3 b/man/man3/TAILQ_PREV.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_PREV.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_REMOVE.3 b/man/man3/TAILQ_REMOVE.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_REMOVE.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TAILQ_SWAP.3 b/man/man3/TAILQ_SWAP.3
new file mode 100644
index 000000000..c766ff4e7
--- /dev/null
+++ b/man/man3/TAILQ_SWAP.3
@@ -0,0 +1 @@
+.so man3/tailq.3
diff --git a/man/man3/TIMESPEC_TO_TIMEVAL.3 b/man/man3/TIMESPEC_TO_TIMEVAL.3
new file mode 100644
index 000000000..30ab755d2
--- /dev/null
+++ b/man/man3/TIMESPEC_TO_TIMEVAL.3
@@ -0,0 +1 @@
+.so man3/TIMEVAL_TO_TIMESPEC.3
diff --git a/man/man3/TIMEVAL_TO_TIMESPEC.3 b/man/man3/TIMEVAL_TO_TIMESPEC.3
new file mode 100644
index 000000000..6cdd72e3e
--- /dev/null
+++ b/man/man3/TIMEVAL_TO_TIMESPEC.3
@@ -0,0 +1,32 @@
+.\" Copyright (C) 2024 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH TIMEVAL_TO_TIMESPEC 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+TIMEVAL_TO_TIMESPEC,
+TIMESPEC_TO_TIMEVAL
+\-
+convert between time structures
+.SH SYNOPSIS
+.nf
+.B #define _GNU_SOURCE
+.B #include <sys/time.h>
+.P
+.BI "void TIMEVAL_TO_TIMESPEC(const struct timeval *" tv ", struct timespec *" ts );
+.BI "void TIMESPEC_TO_TIMEVAL(struct timeval *" tv ", const struct timespec *" ts );
+.fi
+.SH DESCRIPTION
+These macros convert from a
+.BR timeval (3type)
+to a
+.BR timespec (3type)
+structure,
+and vice versa,
+respectively.
+.P
+This is especially useful for writing interfaces that receive a type,
+but are implemented with calls to functions that receive the other one.
+.SH STANDARDS
+GNU,
+BSD.
diff --git a/man/man3/_Generic.3 b/man/man3/_Generic.3
new file mode 100644
index 000000000..788a117dd
--- /dev/null
+++ b/man/man3/_Generic.3
@@ -0,0 +1,64 @@
+.\" Copyright (C) 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH _Generic 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+_Generic \- type-generic selection
+.SH SYNOPSIS
+.nf
+.BR _Generic( \fIexpression\fP ", type1: " e1 ", " "... /*" \
+", default: " "e */" );
+.fi
+.SH DESCRIPTION
+.BR _Generic ()
+evaluates the path of code under the type selector
+that is compatible with the type of the controlling
+.IR expression ,
+or
+.B default:
+if no type is compatible.
+.P
+.I expression
+is not evaluated.
+.P
+This is especially useful for writing type-generic macros,
+that will behave differently depending on the type of the argument.
+.SH STANDARDS
+C11.
+.SH HISTORY
+C11.
+.SH EXAMPLES
+The following program demonstrates how to write
+a replacement for the standard
+.BR imaxabs (3)
+function, which being a function can't really provide what it promises:
+seamlessly upgrading to the widest available type.
+.IP
+.\" SRC BEGIN (_Generic.c)
+.EX
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#define my_imaxabs  _Generic(INTMAX_C(0),  \e
+    long:           labs,                  \e
+    long long:      llabs                  \e
+/*  long long long: lllabs */              \e
+)
+\&
+int
+main(void)
+{
+    off_t  a;
+\&
+    a = \-42;
+    printf("imaxabs(%jd) == %jd\en", (intmax_t) a, my_imaxabs(a));
+    printf("&imaxabs == %p\en", &my_imaxabs);
+    printf("&labs    == %p\en", &labs);
+    printf("&llabs   == %p\en", &llabs);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
diff --git a/man/man3/_Static_assert.3 b/man/man3/_Static_assert.3
new file mode 100644
index 000000000..30f63531c
--- /dev/null
+++ b/man/man3/_Static_assert.3
@@ -0,0 +1 @@
+.so man3/static_assert.3
diff --git a/man/man3/__after_morecore_hook.3 b/man/man3/__after_morecore_hook.3
new file mode 100644
index 000000000..421aafcbe
--- /dev/null
+++ b/man/man3/__after_morecore_hook.3
@@ -0,0 +1 @@
+.so man3/malloc_hook.3
diff --git a/man/man3/__fbufsize.3 b/man/man3/__fbufsize.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__fbufsize.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__flbf.3 b/man/man3/__flbf.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__flbf.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__fpending.3 b/man/man3/__fpending.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__fpending.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__fpurge.3 b/man/man3/__fpurge.3
new file mode 100644
index 000000000..d7cfd4977
--- /dev/null
+++ b/man/man3/__fpurge.3
@@ -0,0 +1 @@
+.so man3/fpurge.3
diff --git a/man/man3/__freadable.3 b/man/man3/__freadable.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__freadable.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__freading.3 b/man/man3/__freading.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__freading.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__free_hook.3 b/man/man3/__free_hook.3
new file mode 100644
index 000000000..421aafcbe
--- /dev/null
+++ b/man/man3/__free_hook.3
@@ -0,0 +1 @@
+.so man3/malloc_hook.3
diff --git a/man/man3/__fsetlocking.3 b/man/man3/__fsetlocking.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__fsetlocking.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__fwritable.3 b/man/man3/__fwritable.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__fwritable.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__fwriting.3 b/man/man3/__fwriting.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/__fwriting.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/__malloc_hook.3 b/man/man3/__malloc_hook.3
new file mode 100644
index 000000000..421aafcbe
--- /dev/null
+++ b/man/man3/__malloc_hook.3
@@ -0,0 +1 @@
+.so man3/malloc_hook.3
diff --git a/man/man3/__malloc_initialize_hook.3 b/man/man3/__malloc_initialize_hook.3
new file mode 100644
index 000000000..421aafcbe
--- /dev/null
+++ b/man/man3/__malloc_initialize_hook.3
@@ -0,0 +1 @@
+.so man3/malloc_hook.3
diff --git a/man/man3/__memalign_hook.3 b/man/man3/__memalign_hook.3
new file mode 100644
index 000000000..421aafcbe
--- /dev/null
+++ b/man/man3/__memalign_hook.3
@@ -0,0 +1 @@
+.so man3/malloc_hook.3
diff --git a/man/man3/__ppc_get_timebase.3 b/man/man3/__ppc_get_timebase.3
new file mode 100644
index 000000000..ee922c130
--- /dev/null
+++ b/man/man3/__ppc_get_timebase.3
@@ -0,0 +1,99 @@
+.\" Copyright (c) 2012, IBM Corporation.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH __ppc_get_timebase 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+__ppc_get_timebase, __ppc_get_timebase_freq \- get the current value
+of the Time Base Register on Power architecture and its frequency.
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/platform/ppc.h>
+.P
+.B uint64_t __ppc_get_timebase(void);
+.B uint64_t __ppc_get_timebase_freq(void);
+.fi
+.SH DESCRIPTION
+.BR __ppc_get_timebase ()
+reads the current value of the Time Base Register and returns its
+value, while
+.BR __ppc_get_timebase_freq ()
+returns the frequency in which the Time Base Register is updated.
+.P
+The Time Base Register is a 64-bit register provided by Power Architecture
+processors.
+It stores a monotonically incremented value that is updated at a
+system-dependent frequency that may be different from the processor
+frequency.
+.SH RETURN VALUE
+.BR __ppc_get_timebase ()
+returns a 64-bit unsigned integer that represents the current value of the
+Time Base Register.
+.P
+.BR __ppc_get_timebase_freq ()
+returns a 64-bit unsigned integer that represents the frequency at
+which the Time Base Register is updated.
+.SH STANDARDS
+GNU.
+.SH HISTORY
+.TP
+.BR __ppc_get_timebase ()
+.\" commit d9dc34cd569bcfe714fe8c708e58c028106e8b2e
+glibc 2.16.
+.TP
+.BR __ppc_get_timebase_freq ()
+.\" commit 8ad11b9a9cf1de82bd7771306b42070b91417c11
+glibc 2.17.
+.SH EXAMPLES
+The following program will calculate the time, in microseconds, spent
+between two calls to
+.BR __ppc_get_timebase ().
+.SS Program source
+\&
+.\" SRC BEGIN (__ppc_get_timebase.c)
+.EX
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/platform/ppc.h>
+\&
+/* Maximum value of the Time Base Register: 2\[ha]60 \- 1.
+   Source: POWER ISA.  */
+#define MAX_TB 0xFFFFFFFFFFFFFFF
+\&
+int
+main(void)
+{
+    uint64_t tb1, tb2, diff;
+    uint64_t freq;
+\&
+    freq = __ppc_get_timebase_freq();
+    printf("Time Base frequency = %"PRIu64" Hz\en", freq);
+\&
+    tb1 = __ppc_get_timebase();
+\&
+    // Do some stuff...
+\&
+    tb2 = __ppc_get_timebase();
+\&
+    if (tb2 > tb1) {
+        diff = tb2 \- tb1;
+    } else {
+        /* Treat Time Base Register overflow.  */
+        diff = (MAX_TB \- tb2) + tb1;
+    }
+\&
+    printf("Elapsed time  = %1.2f usecs\en",
+           (double) diff * 1000000 / freq);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR time (2),
+.BR usleep (3)
diff --git a/man/man3/__ppc_get_timebase_freq.3 b/man/man3/__ppc_get_timebase_freq.3
new file mode 100644
index 000000000..8599293bd
--- /dev/null
+++ b/man/man3/__ppc_get_timebase_freq.3
@@ -0,0 +1 @@
+.so man3/__ppc_get_timebase.3
diff --git a/man/man3/__ppc_mdoio.3 b/man/man3/__ppc_mdoio.3
new file mode 100644
index 000000000..c9f047fbe
--- /dev/null
+++ b/man/man3/__ppc_mdoio.3
@@ -0,0 +1 @@
+.so man3/__ppc_yield.3
diff --git a/man/man3/__ppc_mdoom.3 b/man/man3/__ppc_mdoom.3
new file mode 100644
index 000000000..c9f047fbe
--- /dev/null
+++ b/man/man3/__ppc_mdoom.3
@@ -0,0 +1 @@
+.so man3/__ppc_yield.3
diff --git a/man/man3/__ppc_set_ppr_low.3 b/man/man3/__ppc_set_ppr_low.3
new file mode 100644
index 000000000..a6d6cf3fa
--- /dev/null
+++ b/man/man3/__ppc_set_ppr_low.3
@@ -0,0 +1 @@
+.so man3/__ppc_set_ppr_med.3
diff --git a/man/man3/__ppc_set_ppr_med.3 b/man/man3/__ppc_set_ppr_med.3
new file mode 100644
index 000000000..317804438
--- /dev/null
+++ b/man/man3/__ppc_set_ppr_med.3
@@ -0,0 +1,113 @@
+'\" t
+.\" Copyright (c) 2015, 2016 IBM Corporation.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH __ppc_set_ppr_med 3 (date) "Linux man-pages (unreleased)"
+Programmer's Manual"
+.SH NAME
+__ppc_set_ppr_med, __ppc_set_ppr_very_low, __ppc_set_ppr_low,
+__ppc_set_ppr_med_low, __ppc_set_ppr_med_high \-
+Set the Program Priority Register
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/platform/ppc.h>
+.P
+.B void __ppc_set_ppr_med(void);
+.B void __ppc_set_ppr_very_low(void);
+.B void __ppc_set_ppr_low(void);
+.B void __ppc_set_ppr_med_low(void);
+.B void __ppc_set_ppr_med_high(void);
+.fi
+.SH DESCRIPTION
+These functions provide access to the
+.I Program Priority Register
+(PPR) on the Power architecture.
+.P
+The PPR is a 64-bit register that controls the program's priority.
+By adjusting the PPR value the programmer may improve system
+throughput by causing system resources to be used more
+efficiently, especially in contention situations.
+The available unprivileged states are covered by the following functions:
+.TP
+.BR __ppc_set_ppr_med ()
+sets the Program Priority Register value to
+.I medium
+(default).
+.TP
+.BR __ppc_set_ppr_very_low ()
+sets the Program Priority Register value to
+.IR "very low" .
+.TP
+.BR __ppc_set_ppr_low ()
+sets the Program Priority Register value to
+.IR low .
+.TP
+.BR __ppc_set_ppr_med_low ()
+sets the Program Priority Register value to
+.IR "medium low" .
+.P
+The privileged state
+.I medium high
+may also be set during certain time intervals by problem-state (unprivileged)
+programs, with the following function:
+.TP
+.BR __ppc_set_ppr_med_high ()
+sets the Program Priority to
+.IR "medium high" .
+.P
+If the program priority is medium high when the time interval expires or if an
+attempt is made to set the priority to medium high when it is not allowed, the
+priority is set to medium.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR __ppc_set_ppr_med (),
+.BR __ppc_set_ppr_very_low (),
+.BR __ppc_set_ppr_low (),
+.BR __ppc_set_ppr_med_low (),
+.BR __ppc_set_ppr_med_high ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+.TP
+.BR __ppc_set_ppr_med ()
+.TQ
+.BR __ppc_set_ppr_low ()
+.TQ
+.BR __ppc_set_ppr_med_low ()
+glibc 2.18.
+.TP
+.BR __ppc_set_ppr_very_low ()
+.TQ
+.BR __ppc_set_ppr_med_high ()
+glibc 2.23.
+.SH NOTES
+The functions
+.BR __ppc_set_ppr_very_low ()
+and
+.BR __ppc_set_ppr_med_high ()
+will be defined by
+.I <sys/platform/ppc.h>
+if
+.B _ARCH_PWR8
+is defined.
+Availability of these functions can be tested using
+.BR "#ifdef _ARCH_PWR8" .
+.SH SEE ALSO
+.BR __ppc_yield (3)
+.P
+.I Power ISA, Book\~II - Section\ 3.1 (Program Priority Registers)
diff --git a/man/man3/__ppc_set_ppr_med_high.3 b/man/man3/__ppc_set_ppr_med_high.3
new file mode 100644
index 000000000..a6d6cf3fa
--- /dev/null
+++ b/man/man3/__ppc_set_ppr_med_high.3
@@ -0,0 +1 @@
+.so man3/__ppc_set_ppr_med.3
diff --git a/man/man3/__ppc_set_ppr_med_low.3 b/man/man3/__ppc_set_ppr_med_low.3
new file mode 100644
index 000000000..a6d6cf3fa
--- /dev/null
+++ b/man/man3/__ppc_set_ppr_med_low.3
@@ -0,0 +1 @@
+.so man3/__ppc_set_ppr_med.3
diff --git a/man/man3/__ppc_set_ppr_very_low.3 b/man/man3/__ppc_set_ppr_very_low.3
new file mode 100644
index 000000000..a6d6cf3fa
--- /dev/null
+++ b/man/man3/__ppc_set_ppr_very_low.3
@@ -0,0 +1 @@
+.so man3/__ppc_set_ppr_med.3
diff --git a/man/man3/__ppc_yield.3 b/man/man3/__ppc_yield.3
new file mode 100644
index 000000000..8ccbcdac7
--- /dev/null
+++ b/man/man3/__ppc_yield.3
@@ -0,0 +1,67 @@
+'\" t
+.\" Copyright (c) 2015, IBM Corporation.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH __ppc_yield 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+__ppc_yield, __ppc_mdoio, __ppc_mdoom \-
+Hint the processor to release shared resources
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/platform/ppc.h>
+.P
+.B void __ppc_yield(void);
+.B void __ppc_mdoio(void);
+.B void __ppc_mdoom(void);
+.fi
+.SH DESCRIPTION
+These functions
+provide hints about the usage of resources that are shared with other
+processors on the Power architecture.
+They can be used, for example, if a program waiting on a lock intends
+to divert the shared resources to be used by other processors.
+.P
+.BR __ppc_yield ()
+provides a hint that performance will probably be improved if shared
+resources dedicated to the executing processor are released for use by
+other processors.
+.P
+.BR __ppc_mdoio ()
+provides a hint that performance will probably be improved if shared
+resources dedicated to the executing processor are released until all
+outstanding storage accesses to caching-inhibited storage have been
+completed.
+.P
+.BR __ppc_mdoom ()
+provides a hint that performance will probably be improved if shared
+resources dedicated to the executing processor are released until all
+outstanding storage accesses to cacheable storage for which the data
+is not in the cache have been completed.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR __ppc_yield (),
+.BR __ppc_mdoio (),
+.BR __ppc_mdoom ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.18.
+.SH SEE ALSO
+.BR __ppc_set_ppr_med (3)
+.P
+.I Power ISA, Book\~II - Section\~3.2 ("or" architecture)
diff --git a/man/man3/__realloc_hook.3 b/man/man3/__realloc_hook.3
new file mode 100644
index 000000000..421aafcbe
--- /dev/null
+++ b/man/man3/__realloc_hook.3
@@ -0,0 +1 @@
+.so man3/malloc_hook.3
diff --git a/man/man3/__setfpucw.3 b/man/man3/__setfpucw.3
new file mode 100644
index 000000000..647fece4a
--- /dev/null
+++ b/man/man3/__setfpucw.3
@@ -0,0 +1,72 @@
+.\" Written Sat Mar  8 10:35:08 MEZ 1997 by
+.\" J. "MUFTI" Scheurich (mufti@csv.ica.uni-stuttgart.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH __setfpucw 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+__setfpucw \- set FPU control word on i386 architecture (obsolete)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <i386/fpu_control.h>
+.P
+.BI "[[deprecated]] void __setfpucw(unsigned short " control_word );
+.fi
+.SH DESCRIPTION
+.BR __setfpucw ()
+transfers
+.I control_word
+to the registers of the FPU (floating-point unit) on the i386 architecture.
+This was used to control floating-point precision,
+rounding and floating-point exceptions.
+.SH STANDARDS
+GNU.
+.SH HISTORY
+Removed in glibc 2.1.
+.SH NOTES
+There are new functions from C99, with prototypes in
+.IR <fenv.h> ,
+to control FPU rounding modes, like
+.BR fegetround (3),
+.BR fesetround (3),
+and the floating-point environment, like
+.BR fegetenv (3),
+.BR feholdexcept (3),
+.BR fesetenv (3),
+.BR feupdateenv (3),
+and FPU exception handling, like
+.BR feclearexcept (3),
+.BR fegetexceptflag (3),
+.BR feraiseexcept (3),
+.BR fesetexceptflag (3),
+and
+.BR fetestexcept (3).
+.P
+If direct access to the FPU control word is still needed, the
+.B _FPU_GETCW
+and
+.B _FPU_SETCW
+macros from
+.I <fpu_control.h>
+can be used.
+.SH EXAMPLES
+.B __setfpucw(0x1372)
+.P
+Set FPU control word on the i386 architecture to
+.RS
+.PD 0
+.IP \[bu] 3
+extended precision
+.IP \[bu]
+rounding to nearest
+.IP \[bu]
+exceptions on overflow, zero divide and NaN
+.PD
+.RE
+.SH SEE ALSO
+.BR feclearexcept (3)
+.P
+.I <fpu_control.h>
diff --git a/man/man3/_flushlbf.3 b/man/man3/_flushlbf.3
new file mode 100644
index 000000000..fb0e7c0d7
--- /dev/null
+++ b/man/man3/_flushlbf.3
@@ -0,0 +1 @@
+.so man3/stdio_ext.3
diff --git a/man/man3/a64l.3 b/man/man3/a64l.3
new file mode 100644
index 000000000..9d20e94df
--- /dev/null
+++ b/man/man3/a64l.3
@@ -0,0 +1,111 @@
+'\" t
+\t
+.\" Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Corrected, aeb, 2002-05-30
+.\"
+.TH a64l 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+a64l, l64a \- convert between long and base-64
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "long a64l(const char *" str64 );
+.BI "char *l64a(long " value );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR a64l (),
+.BR l64a ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions provide a conversion between 32-bit long integers
+and little-endian base-64 ASCII strings (of length zero to six).
+If the string used as argument for
+.BR a64l ()
+has length greater than six, only the first six bytes are used.
+If the type
+.I long
+has more than 32 bits, then
+.BR l64a ()
+uses only the low order 32 bits of
+.IR value ,
+and
+.BR a64l ()
+sign-extends its 32-bit result.
+.P
+The 64 digits in the base-64 system are:
+.P
+.RS
+.nf
+\&\[aq].\[aq]	represents a 0
+\&\[aq]/\[aq]	represents a 1
+0-9	represent  2-11
+A-Z	represent 12-37
+a-z	represent 38-63
+.fi
+.RE
+.P
+So 123 = 59*64\[ha]0 + 1*64\[ha]1 = "v/".
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR l64a ()
+T}	Thread safety	MT-Unsafe race:l64a
+T{
+.na
+.nh
+.BR a64l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The value returned by
+.BR l64a ()
+may be a pointer to a static buffer, possibly overwritten
+by later calls.
+.P
+The behavior of
+.BR l64a ()
+is undefined when
+.I value
+is negative.
+If
+.I value
+is zero, it returns an empty string.
+.P
+These functions are broken before glibc 2.2.5
+(puts most significant digit first).
+.P
+This is not the encoding used by
+.BR uuencode (1).
+.SH SEE ALSO
+.BR uuencode (1),
+.\" .BR itoa (3),
+.BR strtoul (3)
diff --git a/man/man3/abort.3 b/man/man3/abort.3
new file mode 100644
index 000000000..e83077e7e
--- /dev/null
+++ b/man/man3/abort.3
@@ -0,0 +1,99 @@
+'\" t
+.\" Copyright 2007 (C) Michael Kerrisk <mtk.manpages@gmail.com>
+.\" some parts Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 21:46:21 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Aug  4 10:51:53 2000 - patch from Joseph S. Myers
+.\" 2007-12-15, mtk, Mostly rewritten
+.\"
+.TH abort 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+abort \- cause abnormal process termination
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.B [[noreturn]] void abort(void);
+.fi
+.SH DESCRIPTION
+The
+.BR abort ()
+function first unblocks the
+.B SIGABRT
+signal, and then raises that signal for the calling process
+(as though
+.BR raise (3)
+was called).
+This results in the abnormal termination of the process unless the
+.B SIGABRT
+signal is caught and the signal handler does not return
+(see
+.BR longjmp (3)).
+.P
+If the
+.B SIGABRT
+signal is ignored, or caught by a handler that returns, the
+.BR abort ()
+function will still terminate the process.
+It does this by restoring the default disposition for
+.B SIGABRT
+and then raising the signal for a second time.
+.P
+As with other cases of abnormal termination the functions registered with
+.BR atexit (3)
+and
+.BR on_exit (3)
+are not called.
+.SH RETURN VALUE
+The
+.BR abort ()
+function never returns.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR abort ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+SVr4, POSIX.1-2001, 4.3BSD, C89.
+.P
+Up until glibc 2.26,
+if the
+.BR abort ()
+function caused process termination,
+all open streams were closed and flushed (as with
+.BR fclose (3)).
+However, in some cases this could result in deadlocks and data corruption.
+Therefore, starting with glibc 2.27,
+.\" glibc commit 91e7cf982d0104f0e71770f5ae8e3faf352dea9f
+.BR abort ()
+terminates the process without flushing streams.
+POSIX.1 permits either possible behavior, saying that
+.BR abort ()
+"may include an attempt to effect fclose() on all open streams".
+.SH SEE ALSO
+.BR gdb (1),
+.BR sigaction (2),
+.BR assert (3),
+.BR exit (3),
+.BR longjmp (3),
+.BR raise (3)
diff --git a/man/man3/abs.3 b/man/man3/abs.3
new file mode 100644
index 000000000..2b61e7787
--- /dev/null
+++ b/man/man3/abs.3
@@ -0,0 +1,124 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Mon Mar 29 22:31:13 1993, David Metcalfe
+.\" Modified Sun Jun  6 23:27:50 1993, David Metcalfe
+.\" Modified Sat Jul 24 21:45:37 1993, Rik Faith (faith@cs.unc.edu)
+.\" Modified Sat Dec 16 15:02:59 2000, Joseph S. Myers
+.\"
+.TH abs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+abs, labs, llabs, imaxabs \- compute the absolute value of an integer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int abs(int " j );
+.BI "long labs(long " j );
+.BI "long long llabs(long long " j );
+.P
+.B #include <inttypes.h>
+.P
+.BI "intmax_t imaxabs(intmax_t " j );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR llabs ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR abs ()
+function computes the absolute value of the integer
+argument \fIj\fP.
+The
+.BR labs (),
+.BR llabs (),
+and
+.BR imaxabs ()
+functions compute the absolute value of the argument \fIj\fP of the
+appropriate integer type for the function.
+.SH RETURN VALUE
+Returns the absolute value of the integer argument, of the appropriate
+integer type for the function.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR abs (),
+.BR labs (),
+.BR llabs (),
+.BR imaxabs ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99, SVr4, 4.3BSD.
+.\" POSIX.1 (1996 edition) requires only the
+.\" .BR abs ()
+.\" function.
+.P
+C89 only
+includes the
+.BR abs ()
+and
+.BR labs ()
+functions; the functions
+.BR llabs ()
+and
+.BR imaxabs ()
+were added in C99.
+.SH NOTES
+Trying to take the absolute value of the most negative integer
+is not defined.
+.P
+The
+.BR llabs ()
+function is included since glibc 2.0.
+The
+.BR imaxabs ()
+function is included since glibc 2.1.1.
+.P
+For
+.BR llabs ()
+to be declared, it may be necessary to define
+\fB_ISOC99_SOURCE\fP or \fB_ISOC9X_SOURCE\fP (depending on the
+version of glibc) before including any standard headers.
+.P
+By default,
+GCC handles
+.BR abs (),
+.BR labs (),
+and (since GCC 3.0)
+.BR llabs ()
+and
+.BR imaxabs ()
+as built-in functions.
+.SH SEE ALSO
+.BR cabs (3),
+.BR ceil (3),
+.BR fabs (3),
+.BR floor (3),
+.BR rint (3)
diff --git a/man/man3/acos.3 b/man/man3/acos.3
new file mode 100644
index 000000000..048eea0e3
--- /dev/null
+++ b/man/man3/acos.3
@@ -0,0 +1,121 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-25 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH acos 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+acos, acosf, acosl \- arc cosine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double acos(double " x );
+.BI "float acosf(float " x );
+.BI "long double acosl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR acosf (),
+.BR acosl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions calculate the arc cosine of
+.IR x ;
+that is
+the value whose cosine is
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the arc cosine of
+.I x
+in radians; the return value is in the range [0,\ pi].
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +1,
++0 is returned.
+.P
+If
+.I x
+is positive infinity or negative infinity,
+a domain error occurs,
+and a NaN is returned.
+.P
+If
+.I x
+is outside the range [\-1,\ 1],
+a domain error occurs,
+and a NaN is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is outside the range [\-1,\ 1]
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR acos (),
+.BR acosf (),
+.BR acosl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+C89, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR asin (3),
+.BR atan (3),
+.BR atan2 (3),
+.BR cacos (3),
+.BR cos (3),
+.BR sin (3),
+.BR tan (3)
diff --git a/man/man3/acosf.3 b/man/man3/acosf.3
new file mode 100644
index 000000000..66104f71b
--- /dev/null
+++ b/man/man3/acosf.3
@@ -0,0 +1 @@
+.so man3/acos.3
diff --git a/man/man3/acosh.3 b/man/man3/acosh.3
new file mode 100644
index 000000000..0874baa94
--- /dev/null
+++ b/man/man3/acosh.3
@@ -0,0 +1,124 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-25 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH acosh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+acosh, acoshf, acoshl \- inverse hyperbolic cosine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double acosh(double " x );
+.BI "float acoshf(float " x );
+.BI "long double acoshl(long double " x );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR acosh ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR acoshf (),
+.BR acoshl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions calculate the inverse hyperbolic cosine of
+.IR x ;
+that is the value whose hyperbolic cosine is
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the inverse hyperbolic cosine of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +1, +0 is returned.
+.P
+If
+.I x
+is positive infinity, positive infinity is returned.
+.P
+If
+.I x
+is less than 1,
+a domain error occurs,
+and the functions return a NaN.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is less than 1
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR acosh (),
+.BR acoshf (),
+.BR acoshl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR asinh (3),
+.BR atanh (3),
+.BR cacosh (3),
+.BR cosh (3),
+.BR sinh (3),
+.BR tanh (3)
diff --git a/man/man3/acoshf.3 b/man/man3/acoshf.3
new file mode 100644
index 000000000..f0f5c7a00
--- /dev/null
+++ b/man/man3/acoshf.3
@@ -0,0 +1 @@
+.so man3/acosh.3
diff --git a/man/man3/acoshl.3 b/man/man3/acoshl.3
new file mode 100644
index 000000000..f0f5c7a00
--- /dev/null
+++ b/man/man3/acoshl.3
@@ -0,0 +1 @@
+.so man3/acosh.3
diff --git a/man/man3/acosl.3 b/man/man3/acosl.3
new file mode 100644
index 000000000..66104f71b
--- /dev/null
+++ b/man/man3/acosl.3
@@ -0,0 +1 @@
+.so man3/acos.3
diff --git a/man/man3/addmntent.3 b/man/man3/addmntent.3
new file mode 100644
index 000000000..3c2bb35c9
--- /dev/null
+++ b/man/man3/addmntent.3
@@ -0,0 +1 @@
+.so man3/getmntent.3
diff --git a/man/man3/addseverity.3 b/man/man3/addseverity.3
new file mode 100644
index 000000000..0244613c5
--- /dev/null
+++ b/man/man3/addseverity.3
@@ -0,0 +1,87 @@
+'\" t
+.\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"  adapted glibc info page
+.\"
+.\"  polished a little, aeb
+.TH addseverity 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+addseverity \- introduce new severity classes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.P
+.B #include <fmtmsg.h>
+.P
+.BI "int addseverity(int " severity ", const char *" s );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR addseverity ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+This function allows the introduction of new severity classes
+which can be addressed by the
+.I severity
+argument of the
+.BR fmtmsg (3)
+function.
+By default, that function knows only how to
+print messages for severity 0-4 (with strings (none), HALT,
+ERROR, WARNING, INFO).
+This call attaches the given string
+.I s
+to the given value
+.IR severity .
+If
+.I s
+is NULL, the severity class with the numeric value
+.I severity
+is removed.
+It is not possible to overwrite or remove one of the default
+severity classes.
+The severity value must be nonnegative.
+.SH RETURN VALUE
+Upon success, the value
+.B MM_OK
+is returned.
+Upon error, the return value is
+.BR MM_NOTOK .
+Possible errors include: out of memory, attempt to remove a
+nonexistent or default severity class.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR addseverity ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+System V.
+.SH NOTES
+New severity classes can also be added by setting the environment variable
+.BR SEV_LEVEL .
+.SH SEE ALSO
+.BR fmtmsg (3)
diff --git a/man/man3/adjtime.3 b/man/man3/adjtime.3
new file mode 100644
index 000000000..db00b410d
--- /dev/null
+++ b/man/man3/adjtime.3
@@ -0,0 +1,152 @@
+'\" t
+.\" Copyright (c) 2006 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH adjtime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+adjtime \- correct the time to synchronize the system clock
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/time.h>
+.P
+.BI "int adjtime(const struct timeval *" delta ", struct timeval *" olddelta );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR adjtime ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR adjtime ()
+function gradually adjusts the system clock (as returned by
+.BR gettimeofday (2)).
+The amount of time by which the clock is to be adjusted is specified
+in the structure pointed to by
+.IR delta .
+This structure has the following form:
+.P
+.in +4n
+.EX
+struct timeval {
+    time_t      tv_sec;     /* seconds */
+    suseconds_t tv_usec;    /* microseconds */
+};
+.EE
+.in
+.P
+If the adjustment in
+.I delta
+is positive, then the system clock is speeded up by some
+small percentage (i.e., by adding a small
+amount of time to the clock value in each second) until the adjustment
+has been completed.
+If the adjustment in
+.I delta
+is negative, then the clock is slowed down in a similar fashion.
+.P
+If a clock adjustment from an earlier
+.BR adjtime ()
+call is already in progress
+at the time of a later
+.BR adjtime ()
+call, and
+.I delta
+is not NULL for the later call, then the earlier adjustment is stopped,
+but any already completed part of that adjustment is not undone.
+.P
+If
+.I olddelta
+is not NULL, then the buffer that it points to is used to return
+the amount of time remaining from any previous adjustment that
+has not yet been completed.
+.SH RETURN VALUE
+On success,
+.BR adjtime ()
+returns 0.
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The adjustment in
+.I delta
+is outside the permitted range.
+.TP
+.B EPERM
+The caller does not have sufficient privilege to adjust the time.
+Under Linux, the
+.B CAP_SYS_TIME
+capability is required.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR adjtime ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD, System V.
+.SH NOTES
+The adjustment that
+.BR adjtime ()
+makes to the clock is carried out in such a manner that the clock
+is always monotonically increasing.
+Using
+.BR adjtime ()
+to adjust the time prevents the problems that could be caused for certain
+applications (e.g.,
+.BR make (1))
+by abrupt positive or negative jumps in the system time.
+.P
+.BR adjtime ()
+is intended to be used to make small adjustments to the system time.
+Most systems impose a limit on the adjustment that can be specified in
+.IR delta .
+In the glibc implementation,
+.I delta
+must be less than or equal to (INT_MAX / 1000000 \- 2)
+and greater than or equal to (INT_MIN / 1000000 + 2)
+(respectively 2145 and \-2145 seconds on i386).
+.SH BUGS
+A longstanding bug
+.\" http://sourceware.org/bugzilla/show_bug?id=2449
+.\" http://bugzilla.kernel.org/show_bug.cgi?id=6761
+meant that if
+.I delta
+was specified as NULL,
+no valid information about the outstanding clock adjustment was returned in
+.IR olddelta .
+(In this circumstance,
+.BR adjtime ()
+should return the outstanding clock adjustment, without changing it.)
+This bug is fixed
+.\" Thanks to the new adjtimex() ADJ_OFFSET_SS_READ flag
+on systems with glibc 2.8 or later and
+Linux kernel 2.6.26 or later.
+.SH SEE ALSO
+.BR adjtimex (2),
+.BR gettimeofday (2),
+.BR time (7)
diff --git a/man/man3/aio_cancel.3 b/man/man3/aio_cancel.3
new file mode 100644
index 000000000..4e32cd2bd
--- /dev/null
+++ b/man/man3/aio_cancel.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH aio_cancel 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_cancel \- cancel an outstanding asynchronous I/O request
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B "#include <aio.h>"
+.P
+.BI "int aio_cancel(int " fd ", struct aiocb *" aiocbp );
+.fi
+.SH DESCRIPTION
+The
+.BR aio_cancel ()
+function attempts to cancel outstanding asynchronous I/O requests
+for the file descriptor
+.IR fd .
+If
+.I aiocbp
+is NULL, all such requests are canceled.
+Otherwise, only the request
+described by the control block pointed to by
+.I aiocbp
+is canceled.
+(See
+.BR aio (7)
+for a description of the
+.I aiocb
+structure.)
+.P
+Normal asynchronous notification occurs for canceled requests (see
+.BR aio (7)
+and
+.BR sigevent (3type)).
+The request return status
+.RB ( aio_return (3))
+is set to \-1, and the request error status
+.RB ( aio_error (3))
+is set to
+.BR ECANCELED .
+The control block of requests that cannot be canceled is not changed.
+.P
+If the request could not be canceled,
+then it will terminate in the usual way after performing the I/O operation.
+(In this case,
+.BR aio_error (3)
+will return the status
+.BR EINPROGRESSS .)
+.P
+If
+.I aiocbp
+is not NULL, and
+.I fd
+differs from the file descriptor with which the asynchronous operation
+was initiated, unspecified results occur.
+.P
+Which operations are cancelable is implementation-defined.
+.\" FreeBSD: not those on raw disk devices.
+.SH RETURN VALUE
+The
+.BR aio_cancel ()
+function returns one of the following values:
+.TP
+.B AIO_CANCELED
+All requests were successfully canceled.
+.TP
+.B AIO_NOTCANCELED
+At least one of the
+requests specified was not canceled because it was in progress.
+In this case, one may check the status of individual requests using
+.BR aio_error (3).
+.TP
+.B AIO_ALLDONE
+All requests had already been completed before the call.
+.TP
+\-1
+An error occurred.
+The cause of the error can be found by inspecting
+.IR errno .
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B ENOSYS
+.BR aio_cancel ()
+is not implemented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aio_cancel ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH EXAMPLES
+See
+.BR aio (7).
+.SH SEE ALSO
+.BR aio_error (3),
+.BR aio_fsync (3),
+.BR aio_read (3),
+.BR aio_return (3),
+.BR aio_suspend (3),
+.BR aio_write (3),
+.BR lio_listio (3),
+.BR aio (7)
diff --git a/man/man3/aio_error.3 b/man/man3/aio_error.3
new file mode 100644
index 000000000..11dcf37d0
--- /dev/null
+++ b/man/man3/aio_error.3
@@ -0,0 +1,95 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH aio_error 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_error \- get error status of asynchronous I/O operation
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B "#include <aio.h>"
+.P
+.BI "int aio_error(const struct aiocb *" aiocbp );
+.fi
+.SH DESCRIPTION
+The
+.BR aio_error ()
+function returns the error status for the asynchronous I/O request
+with control block pointed to by
+.IR aiocbp .
+(See
+.BR aio (7)
+for a description of the
+.I aiocb
+structure.)
+.SH RETURN VALUE
+This function returns one of the following:
+.TP
+.B EINPROGRESS
+if the request has not been
+completed yet.
+.TP
+.B ECANCELED
+if the request was canceled.
+.TP
+.B 0
+if the request completed successfully.
+.TP
+.RB "> " 0
+A positive error number, if the asynchronous I/O operation failed.
+This is the same value that would have been stored in the
+.I errno
+variable in the case of a synchronous
+.BR read (2),
+.BR write (2),
+.BR fsync (2),
+or
+.BR fdatasync (2)
+call.
+.SH ERRORS
+.TP
+.B EINVAL
+.I aiocbp
+does not point at a control block for an asynchronous I/O request
+of which the return status (see
+.BR aio_return (3))
+has not been retrieved yet.
+.TP
+.B ENOSYS
+.BR aio_error ()
+is not implemented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aio_error ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH EXAMPLES
+See
+.BR aio (7).
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_fsync (3),
+.BR aio_read (3),
+.BR aio_return (3),
+.BR aio_suspend (3),
+.BR aio_write (3),
+.BR lio_listio (3),
+.BR aio (7)
diff --git a/man/man3/aio_fsync.3 b/man/man3/aio_fsync.3
new file mode 100644
index 000000000..c435c7e85
--- /dev/null
+++ b/man/man3/aio_fsync.3
@@ -0,0 +1,112 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH aio_fsync 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_fsync \- asynchronous file synchronization
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B "#include <aio.h>"
+.P
+.BI "int aio_fsync(int " op ", struct aiocb *" aiocbp );
+.fi
+.SH DESCRIPTION
+The
+.BR aio_fsync ()
+function does a sync on all outstanding asynchronous I/O operations
+associated with
+.IR aiocbp\->aio_fildes .
+(See
+.BR aio (7)
+for a description of the
+.I aiocb
+structure.)
+.P
+More precisely, if
+.I op
+is
+.BR O_SYNC ,
+then all currently queued I/O operations shall be
+completed as if by a call of
+.BR fsync (2),
+and if
+.I op
+is
+.BR O_DSYNC ,
+this call is the asynchronous analog of
+.BR fdatasync (2).
+.P
+Note that this is a request only; it does not wait for I/O completion.
+.P
+Apart from
+.IR aio_fildes ,
+the only field in the structure pointed to by
+.I aiocbp
+that is used by this call is the
+.I aio_sigevent
+field (a
+.I sigevent
+structure, described in
+.BR sigevent (3type)),
+which indicates the desired type of asynchronous notification at completion.
+All other fields are ignored.
+.SH RETURN VALUE
+On success (the sync request was successfully queued)
+this function returns 0.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+Out of resources.
+.TP
+.B EBADF
+.I aio_fildes
+is not a valid file descriptor open for writing.
+.TP
+.B EINVAL
+Synchronized I/O is not supported for this file, or
+.I op
+is not
+.B O_SYNC
+or
+.BR O_DSYNC .
+.TP
+.B ENOSYS
+.BR aio_fsync ()
+is not implemented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aio_fsync ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_read (3),
+.BR aio_return (3),
+.BR aio_suspend (3),
+.BR aio_write (3),
+.BR lio_listio (3),
+.BR aio (7),
+.BR sigevent (3type)
diff --git a/man/man3/aio_init.3 b/man/man3/aio_init.3
new file mode 100644
index 000000000..79d36f2a5
--- /dev/null
+++ b/man/man3/aio_init.3
@@ -0,0 +1,78 @@
+.\" Copyright (c) 2010 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH aio_init 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_init \- asynchronous I/O initialization
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B "#include <aio.h>"
+.P
+.BI "void aio_init(const struct aioinit *" init );
+.fi
+.SH DESCRIPTION
+The GNU-specific
+.BR aio_init ()
+function allows the caller to provide tuning hints to the
+glibc POSIX AIO implementation.
+Use of this function is optional, but to be effective,
+it must be called before employing any other functions in the POSIX AIO API.
+.P
+The tuning information is provided in the buffer pointed to by the argument
+.IR init .
+This buffer is a structure of the following form:
+.P
+.in +4n
+.EX
+struct aioinit {
+    int aio_threads;    /* Maximum number of threads */
+    int aio_num;        /* Number of expected simultaneous
+                           requests */
+    int aio_locks;      /* Not used */
+    int aio_usedba;     /* Not used */
+    int aio_debug;      /* Not used */
+    int aio_numusers;   /* Not used */
+    int aio_idle_time;  /* Number of seconds before idle thread
+                           terminates (since glibc 2.2) */
+    int aio_reserved;
+};
+.EE
+.in
+.P
+The following fields are used in the
+.I aioinit
+structure:
+.TP
+.I aio_threads
+This field specifies the maximum number of worker threads that
+may be used by the implementation.
+If the number of outstanding I/O operations exceeds this limit,
+then excess operations will be queued until a worker thread becomes free.
+If this field is specified with a value less than 1, the value 1 is used.
+The default value is 20.
+.TP
+.I aio_num
+This field should specify the maximum number of simultaneous I/O requests
+that the caller expects to enqueue.
+If a value less than 32 is specified for this field,
+it is rounded up to 32.
+.\" FIXME . But, if aio_num > 32, the behavior looks strange. See
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=12083
+The default value is 64.
+.TP
+.I aio_idle_time
+This field specifies the amount of time in seconds that a
+worker thread should wait for further requests before terminating,
+after having completed a previous request.
+The default value is 1.
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.SH SEE ALSO
+.BR aio (7)
diff --git a/man/man3/aio_read.3 b/man/man3/aio_read.3
new file mode 100644
index 000000000..d5c5084aa
--- /dev/null
+++ b/man/man3/aio_read.3
@@ -0,0 +1,159 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH aio_read 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_read \- asynchronous read
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B "#include <aio.h>"
+.P
+.BI "int aio_read(struct aiocb *" aiocbp );
+.fi
+.SH DESCRIPTION
+The
+.BR aio_read ()
+function queues the I/O request described by the buffer pointed to by
+.IR aiocbp .
+This function is the asynchronous analog of
+.BR read (2).
+The arguments of the call
+.P
+.in +4n
+.EX
+read(fd, buf, count)
+.EE
+.in
+.P
+correspond (in order) to the fields
+.IR aio_fildes ,
+.IR aio_buf ,
+and
+.I aio_nbytes
+of the structure pointed to by
+.IR aiocbp .
+(See
+.BR aio (7)
+for a description of the
+.I aiocb
+structure.)
+.P
+The data is read starting at the absolute position
+.IR aiocbp\->aio_offset ,
+regardless of the file offset.
+After the call,
+the value of the file offset is unspecified.
+.P
+The "asynchronous" means that this call returns as soon as the
+request has been enqueued; the read may or may not have completed
+when the call returns.
+One tests for completion using
+.BR aio_error (3).
+The return status of a completed I/O operation can be obtained by
+.BR aio_return (3).
+Asynchronous notification of I/O completion can be obtained by setting
+.I aiocbp\->aio_sigevent
+appropriately; see
+.BR sigevent (3type)
+for details.
+.P
+If
+.B _POSIX_PRIORITIZED_IO
+is defined, and this file supports it,
+then the asynchronous operation is submitted at a priority equal
+to that of the calling process minus
+.IR aiocbp\->aio_reqprio .
+.P
+The field
+.I aiocbp\->aio_lio_opcode
+is ignored.
+.P
+No data is read from a regular file beyond its maximum offset.
+.SH RETURN VALUE
+On success, 0 is returned.
+On error, the request is not enqueued, \-1
+is returned, and
+.I errno
+is set to indicate the error.
+If an error is detected only later, it will
+be reported via
+.BR aio_return (3)
+(returns status \-1) and
+.BR aio_error (3)
+(error status\[em]whatever one would have gotten in
+.IR errno ,
+such as
+.BR EBADF ).
+.SH ERRORS
+.TP
+.B EAGAIN
+Out of resources.
+.TP
+.B EBADF
+.I aio_fildes
+is not a valid file descriptor open for reading.
+.TP
+.B EINVAL
+One or more of
+.IR aio_offset ,
+.IR aio_reqprio ,
+or
+.I aio_nbytes
+are invalid.
+.TP
+.B ENOSYS
+.BR aio_read ()
+is not implemented.
+.TP
+.B EOVERFLOW
+The file is a regular file, we start reading before end-of-file
+and want at least one byte, but the starting position is past
+the maximum offset for this file.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aio_read ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH NOTES
+It is a good idea to zero out the control block before use.
+The control block must not be changed while the read operation
+is in progress.
+The buffer area being read into
+.\" or the control block of the operation
+must not be accessed during the operation or undefined results may occur.
+The memory areas involved must remain valid.
+.P
+Simultaneous I/O operations specifying the same
+.I aiocb
+structure produce undefined results.
+.SH EXAMPLES
+See
+.BR aio (7).
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_fsync (3),
+.BR aio_return (3),
+.BR aio_suspend (3),
+.BR aio_write (3),
+.BR lio_listio (3),
+.BR aio (7)
diff --git a/man/man3/aio_return.3 b/man/man3/aio_return.3
new file mode 100644
index 000000000..b3100532a
--- /dev/null
+++ b/man/man3/aio_return.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH aio_return 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_return \- get return status of asynchronous I/O operation
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B "#include <aio.h>"
+.P
+.BI "ssize_t aio_return(struct aiocb *" aiocbp );
+.fi
+.SH DESCRIPTION
+The
+.BR aio_return ()
+function returns the final return status for the asynchronous I/O request
+with control block pointed to by
+.IR aiocbp .
+(See
+.BR aio (7)
+for a description of the
+.I aiocb
+structure.)
+.P
+This function should be called only once for any given request, after
+.BR aio_error (3)
+returns something other than
+.BR EINPROGRESS .
+.SH RETURN VALUE
+If the asynchronous I/O operation has completed, this function returns
+the value that would have been returned in case of a synchronous
+.BR read (2),
+.BR write (2),
+.BR fsync (2),
+or
+.BR fdatasync (2),
+call.
+On error, \-1 is returned, and \fIerrno\fP is set to indicate the error.
+.P
+If the asynchronous I/O operation has not yet completed,
+the return value and effect of
+.BR aio_return ()
+are undefined.
+.SH ERRORS
+.TP
+.B EINVAL
+.I aiocbp
+does not point at a control block for an asynchronous I/O request
+of which the return status has not been retrieved yet.
+.TP
+.B ENOSYS
+.BR aio_return ()
+is not implemented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aio_return ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH EXAMPLES
+See
+.BR aio (7).
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_fsync (3),
+.BR aio_read (3),
+.BR aio_suspend (3),
+.BR aio_write (3),
+.BR lio_listio (3),
+.BR aio (7)
diff --git a/man/man3/aio_suspend.3 b/man/man3/aio_suspend.3
new file mode 100644
index 000000000..4abec4025
--- /dev/null
+++ b/man/man3/aio_suspend.3
@@ -0,0 +1,143 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (C) 2010 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH aio_suspend 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_suspend \- wait for asynchronous I/O operation or timeout
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.P
+.B "#include <aio.h>"
+.P
+.BI "int aio_suspend(const struct aiocb *const " aiocb_list "[], int " nitems ,
+.BI "                const struct timespec *restrict " timeout );
+.fi
+.SH DESCRIPTION
+The
+.BR aio_suspend ()
+function suspends the calling thread until one of the following occurs:
+.IP \[bu] 3
+One or more of the asynchronous I/O requests in the list
+.I aiocb_list
+has completed.
+.IP \[bu]
+A signal is delivered.
+.IP \[bu]
+.I timeout
+is not NULL and the specified time interval has passed.
+(For details of the
+.I timespec
+structure, see
+.BR nanosleep (2).)
+.P
+The
+.I nitems
+argument specifies the number of items in
+.IR aiocb_list .
+Each item in the list pointed to by
+.I aiocb_list
+must be either NULL (and then is ignored),
+or a pointer to a control block on which I/O was initiated using
+.BR aio_read (3),
+.BR aio_write (3),
+or
+.BR lio_listio (3).
+(See
+.BR aio (7)
+for a description of the
+.I aiocb
+structure.)
+.P
+If
+.B CLOCK_MONOTONIC
+is supported, this clock is used to measure
+the timeout interval (see
+.BR clock_gettime (2)).
+.SH RETURN VALUE
+If this function returns after completion of one of the I/O
+requests specified in
+.IR aiocb_list ,
+0 is returned.
+Otherwise, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The call timed out before any of the indicated operations
+had completed.
+.TP
+.B EINTR
+The call was ended by signal
+(possibly the completion signal of one of the operations we were
+waiting for); see
+.BR signal (7).
+.TP
+.B ENOSYS
+.BR aio_suspend ()
+is not implemented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aio_suspend ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.P
+POSIX doesn't specify the parameters to be
+.IR restrict ;
+that is specific to glibc.
+.SH NOTES
+One can achieve polling by using a non-NULL
+.I timeout
+that specifies a zero time interval.
+.P
+If one or more of the asynchronous I/O operations specified in
+.I aiocb_list
+has already completed at the time of the call to
+.BR aio_suspend (),
+then the call returns immediately.
+.P
+To determine which I/O operations have completed
+after a successful return from
+.BR aio_suspend (),
+use
+.BR aio_error (3)
+to scan the list of
+.I aiocb
+structures pointed to by
+.IR aiocb_list .
+.SH BUGS
+The glibc implementation of
+.BR aio_suspend ()
+is not async-signal-safe,
+.\" FIXME . https://sourceware.org/bugzilla/show_bug.cgi?id=13172
+in violation of the requirements of POSIX.1.
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_fsync (3),
+.BR aio_read (3),
+.BR aio_return (3),
+.BR aio_write (3),
+.BR lio_listio (3),
+.BR aio (7),
+.BR time (7)
diff --git a/man/man3/aio_write.3 b/man/man3/aio_write.3
new file mode 100644
index 000000000..55d62a84b
--- /dev/null
+++ b/man/man3/aio_write.3
@@ -0,0 +1,161 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH aio_write 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio_write \- asynchronous write
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B "#include <aio.h>"
+.P
+.BI "int aio_write(struct aiocb *" aiocbp );
+.fi
+.SH DESCRIPTION
+The
+.BR aio_write ()
+function queues the I/O request described by the buffer pointed to by
+.IR aiocbp .
+This function is the asynchronous analog of
+.BR write (2).
+The arguments of the call
+.P
+.in +4n
+.EX
+write(fd, buf, count)
+.EE
+.in
+.P
+correspond (in order) to the fields
+.IR aio_fildes ,
+.IR aio_buf ,
+and
+.I aio_nbytes
+of the structure pointed to by
+.IR aiocbp .
+(See
+.BR aio (7)
+for a description of the
+.I aiocb
+structure.)
+.P
+If
+.B O_APPEND
+is not set, the data is written starting at the
+absolute position
+.IR aiocbp\->aio_offset ,
+regardless of the file offset.
+If
+.B O_APPEND
+is set, data is written at the end of the file in the same order as
+.BR aio_write ()
+calls are made.
+After the call, the value of the file offset is unspecified.
+.P
+The "asynchronous" means that this call returns as soon as the
+request has been enqueued; the write may or may not have completed
+when the call returns.
+One tests for completion using
+.BR aio_error (3).
+The return status of a completed I/O operation can be obtained
+.BR aio_return (3).
+Asynchronous notification of I/O completion can be obtained by setting
+.I aiocbp\->aio_sigevent
+appropriately; see
+.BR sigevent (3type)
+for details.
+.P
+If
+.B _POSIX_PRIORITIZED_IO
+is defined, and this file supports it,
+then the asynchronous operation is submitted at a priority equal
+to that of the calling process minus
+.IR aiocbp\->aio_reqprio .
+.P
+The field
+.I aiocbp\->aio_lio_opcode
+is ignored.
+.P
+No data is written to a regular file beyond its maximum offset.
+.SH RETURN VALUE
+On success, 0 is returned.
+On error, the request is not enqueued, \-1
+is returned, and
+.I errno
+is set to indicate the error.
+If an error is detected only later, it will
+be reported via
+.BR aio_return (3)
+(returns status \-1) and
+.BR aio_error (3)
+(error status\[em]whatever one would have gotten in
+.IR errno ,
+such as
+.BR EBADF ).
+.SH ERRORS
+.TP
+.B EAGAIN
+Out of resources.
+.TP
+.B EBADF
+.I aio_fildes
+is not a valid file descriptor open for writing.
+.TP
+.B EFBIG
+The file is a regular file, we want to write at least one byte,
+but the starting position is at or beyond the maximum offset for this file.
+.TP
+.B EINVAL
+One or more of
+.IR aio_offset ,
+.IR aio_reqprio ,
+.I aio_nbytes
+are invalid.
+.TP
+.B ENOSYS
+.BR aio_write ()
+is not implemented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aio_write ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH NOTES
+It is a good idea to zero out the control block before use.
+The control block must not be changed while the write operation
+is in progress.
+The buffer area being written out
+.\" or the control block of the operation
+must not be accessed during the operation or undefined results may occur.
+The memory areas involved must remain valid.
+.P
+Simultaneous I/O operations specifying the same
+.I aiocb
+structure produce undefined results.
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_fsync (3),
+.BR aio_read (3),
+.BR aio_return (3),
+.BR aio_suspend (3),
+.BR lio_listio (3),
+.BR aio (7)
diff --git a/man/man3/aligned_alloc.3 b/man/man3/aligned_alloc.3
new file mode 100644
index 000000000..791d4c801
--- /dev/null
+++ b/man/man3/aligned_alloc.3
@@ -0,0 +1 @@
+.so man3/posix_memalign.3
diff --git a/man/man3/alloca.3 b/man/man3/alloca.3
new file mode 100644
index 000000000..d06f43eda
--- /dev/null
+++ b/man/man3/alloca.3
@@ -0,0 +1,138 @@
+'\" t
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)alloca.3	5.1 (Berkeley) 5/2/91
+.\"
+.\" Converted Mon Nov 29 11:05:55 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 23:41:56 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2002-07-17, aeb
+.\" 2008-01-24, mtk:
+.\"     Various rewrites and additions (notes on longjmp() and SIGSEGV).
+.\"     Weaken warning against use of alloca() (as per Debian bug 461100).
+.\"
+.TH alloca 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+alloca \- allocate memory that is automatically freed
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <alloca.h>
+.P
+.BI "void *alloca(size_t " size );
+.fi
+.SH DESCRIPTION
+The
+.BR alloca ()
+function allocates
+.I size
+bytes of space in the stack frame of the caller.
+This temporary space is
+automatically freed when the function that called
+.BR alloca ()
+returns to its caller.
+.SH RETURN VALUE
+The
+.BR alloca ()
+function returns a pointer to the beginning of the allocated space.
+If the allocation causes stack overflow, program behavior is undefined.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR alloca ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+PWB, 32V.
+.SH NOTES
+The
+.BR alloca ()
+function is machine- and compiler-dependent.
+Because it allocates from the stack, it's faster than
+.BR malloc (3)
+and
+.BR free (3).
+In certain cases,
+it can also simplify memory deallocation in applications that use
+.BR longjmp (3)
+or
+.BR siglongjmp (3).
+Otherwise, its use is discouraged.
+.P
+Because the space allocated by
+.BR alloca ()
+is allocated within the stack frame,
+that space is automatically freed if the function return
+is jumped over by a call to
+.BR longjmp (3)
+or
+.BR siglongjmp (3).
+.P
+The space allocated by
+.BR alloca ()
+is
+.I not
+automatically deallocated if the pointer that refers to it
+simply goes out of scope.
+.P
+Do not attempt to
+.BR free (3)
+space allocated by
+.BR alloca ()!
+.P
+By necessity,
+.BR alloca ()
+is a compiler built-in, also known as
+.BR __builtin_alloca ().
+By default, modern compilers automatically translate all uses of
+.BR alloca ()
+into the built-in, but this is forbidden if standards conformance is requested
+.RI ( "\-ansi" ,
+.IR "\-std=c*" ),
+in which case
+.I <alloca.h>
+is required, lest a symbol dependency be emitted.
+.P
+The fact that
+.BR alloca ()
+is a built-in means it is impossible to take its address
+or to change its behavior by linking with a different library.
+.P
+Variable length arrays (VLAs) are part of the C99 standard,
+optional since C11, and can be used for a similar purpose.
+However, they do not port to standard C++, and, being variables,
+live in their block scope and don't have an allocator-like interface,
+making them unfit for implementing functionality like
+.BR strdupa (3).
+.SH BUGS
+Due to the nature of the stack, it is impossible to check if the allocation
+would overflow the space available, and, hence, neither is indicating an error.
+(However, the program is likely to receive a
+.B SIGSEGV
+signal if it attempts to access unavailable space.)
+.P
+On many systems
+.BR alloca ()
+cannot be used inside the list of arguments of a function call, because
+the stack space reserved by
+.BR alloca ()
+would appear on the stack in the middle of the space for the
+function arguments.
+.SH SEE ALSO
+.BR brk (2),
+.BR longjmp (3),
+.BR malloc (3)
diff --git a/man/man3/alphasort.3 b/man/man3/alphasort.3
new file mode 100644
index 000000000..7e757c7a0
--- /dev/null
+++ b/man/man3/alphasort.3
@@ -0,0 +1 @@
+.so man3/scandir.3
diff --git a/man/man3/arc4random.3 b/man/man3/arc4random.3
new file mode 100644
index 000000000..bb7591c1c
--- /dev/null
+++ b/man/man3/arc4random.3
@@ -0,0 +1,109 @@
+'\" t
+.\" Copyright (C) 2023 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH arc4random 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+arc4random, arc4random_uniform, arc4random_buf
+\- cryptographically-secure pseudorandom number generator
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.B uint32_t arc4random(void);
+.BI "uint32_t arc4random_uniform(uint32_t " upper_bound );
+.BI "void arc4random_buf(void " buf [. n "], size_t " n );
+.fi
+.SH DESCRIPTION
+These functions give cryptographically-secure pseudorandom numbers.
+.P
+.BR arc4random ()
+returns a uniformly-distributed value.
+.P
+.BR arc4random_uniform ()
+returns a uniformly-distributed value less than
+.I upper_bound
+(see BUGS).
+.P
+.BR arc4random_buf ()
+fills the memory pointed to by
+.IR buf ,
+with
+.I n
+bytes of pseudorandom data.
+.P
+The
+.BR rand (3)
+and
+.BR drand48 (3)
+families of functions should only be used where
+the quality of the pseudorandom numbers is not a concern
+.I and
+there's a need for repeatability of the results.
+Unless you meet both of those conditions,
+use the
+.BR arc4random ()
+functions.
+.SH RETURN VALUE
+.BR arc4random ()
+returns a pseudorandom number.
+.P
+.BR arc4random_uniform ()
+returns a pseudorandom number less than
+.I upper_bound
+for valid input, or
+.B 0
+when
+.I upper_bound
+is invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR arc4random (),
+.BR arc4random_uniform (),
+.BR arc4random_buf ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+OpenBSD 2.1,
+FreeBSD 3.0,
+NetBSD 1.6,
+DragonFly 1.0,
+libbsd,
+glibc 2.36.
+.SH BUGS
+An
+.I upper_bound
+of
+.B 0
+doesn't make sense in a call to
+.BR arc4random_uniform ().
+Such a call will fail, and return
+.BR 0 .
+Be careful,
+since that value is
+.I not
+less than
+.IR upper_bound .
+In some cases,
+such as accessing an array,
+using that value could result in Undefined Behavior.
+.SH SEE ALSO
+.BR getrandom (3),
+.BR rand (3),
+.BR drand48 (3),
+.BR random (7)
diff --git a/man/man3/arc4random_buf.3 b/man/man3/arc4random_buf.3
new file mode 100644
index 000000000..74a34ce1a
--- /dev/null
+++ b/man/man3/arc4random_buf.3
@@ -0,0 +1 @@
+.so man3/arc4random.3
diff --git a/man/man3/arc4random_uniform.3 b/man/man3/arc4random_uniform.3
new file mode 100644
index 000000000..74a34ce1a
--- /dev/null
+++ b/man/man3/arc4random_uniform.3
@@ -0,0 +1 @@
+.so man3/arc4random.3
diff --git a/man/man3/argz.3 b/man/man3/argz.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_add.3 b/man/man3/argz_add.3
new file mode 100644
index 000000000..4b4fc4f8d
--- /dev/null
+++ b/man/man3/argz_add.3
@@ -0,0 +1,237 @@
+'\" t
+.\" Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" based on the description in glibc source and infopages
+.\"
+.\" Corrections and additions, aeb
+.TH argz_add 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+argz_add, argz_add_sep, argz_append, argz_count, argz_create,
+argz_create_sep, argz_delete, argz_extract, argz_insert,
+argz_next, argz_replace, argz_stringify \- functions to handle an argz list
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <argz.h>"
+.P
+.BI "error_t argz_add(char **restrict " argz ", size_t *restrict " argz_len ,
+.BI "                const char *restrict " str );
+.P
+.BI "error_t argz_add_sep(char **restrict " argz \
+", size_t *restrict " argz_len ,
+.BI "                const char *restrict " str ", int " delim );
+.P
+.BI "error_t argz_append(char **restrict " argz ", size_t *restrict " argz_len ,
+.BI "                const char *restrict " buf ", size_t " buf_len );
+.P
+.BI "size_t argz_count(const char *" argz ", size_t " argz_len );
+.P
+.BI "error_t argz_create(char *const " argv "[], char **restrict " argz ,
+.BI "                size_t *restrict " argz_len );
+.P
+.BI "error_t argz_create_sep(const char *restrict " str ", int " sep ,
+.BI "                char **restrict " argz ", size_t *restrict " argz_len );
+.P
+.BI "void argz_delete(char **restrict " argz ", size_t *restrict " argz_len ,
+.BI "                char *restrict " entry );
+.P
+.BI "void argz_extract(const char *restrict " argz ", size_t " argz_len ,
+.BI "                char **restrict " argv );
+.P
+.BI "error_t argz_insert(char **restrict " argz ", size_t *restrict " argz_len ,
+.BI "                char *restrict " before ", const char *restrict " entry );
+.P
+.BI "char *argz_next(const char *restrict " argz ", size_t " argz_len ,
+.BI "                const char *restrict " entry );
+.P
+.BI "error_t argz_replace(char **restrict " argz \
+", size_t *restrict " argz_len ,
+.BI "                const char *restrict " str ", const char *restrict " with ,
+.BI "                unsigned int *restrict " replace_count );
+.P
+.BI "void argz_stringify(char *" argz ", size_t " len ", int " sep );
+.fi
+.SH DESCRIPTION
+These functions are glibc-specific.
+.P
+An argz vector is a pointer to a character buffer together with a length.
+The intended interpretation of the character buffer is an array
+of strings, where the strings are separated by null bytes (\[aq]\e0\[aq]).
+If the length is nonzero, the last byte of the buffer must be a null byte.
+.P
+These functions are for handling argz vectors.
+The pair (NULL,0) is an argz vector, and, conversely,
+argz vectors of length 0 must have null pointer.
+Allocation of nonempty argz vectors is done using
+.BR malloc (3),
+so that
+.BR free (3)
+can be used to dispose of them again.
+.P
+.BR argz_add ()
+adds the string
+.I str
+at the end of the array
+.IR *argz ,
+and updates
+.I *argz
+and
+.IR *argz_len .
+.P
+.BR argz_add_sep ()
+is similar, but splits the string
+.I str
+into substrings separated by the delimiter
+.IR delim .
+For example, one might use this on a UNIX search path with
+delimiter \[aq]:\[aq].
+.P
+.BR argz_append ()
+appends the argz vector
+.RI ( buf ,\  buf_len )
+after
+.RI ( *argz ,\  *argz_len )
+and updates
+.I *argz
+and
+.IR *argz_len .
+(Thus,
+.I *argz_len
+will be increased by
+.IR buf_len .)
+.P
+.BR argz_count ()
+counts the number of strings, that is,
+the number of null bytes (\[aq]\e0\[aq]), in
+.RI ( argz ,\  argz_len ).
+.P
+.BR argz_create ()
+converts a UNIX-style argument vector
+.IR argv ,
+terminated by
+.IR "(char\ *)\ 0" ,
+into an argz vector
+.RI ( *argz ,\  *argz_len ).
+.P
+.BR argz_create_sep ()
+converts the null-terminated string
+.I str
+into an argz vector
+.RI ( *argz ,\  *argz_len )
+by breaking it up at every occurrence of the separator
+.IR sep .
+.P
+.BR argz_delete ()
+removes the substring pointed to by
+.I entry
+from the argz vector
+.RI ( *argz ,\  *argz_len )
+and updates
+.I *argz
+and
+.IR *argz_len .
+.P
+.BR argz_extract ()
+is the opposite of
+.BR argz_create ().
+It takes the argz vector
+.RI ( argz ,\  argz_len )
+and fills the array starting at
+.I argv
+with pointers to the substrings, and a final NULL,
+making a UNIX-style argv vector.
+The array
+.I argv
+must have room for
+.IR argz_count ( argz ", " argz_len ") + 1"
+pointers.
+.P
+.BR argz_insert ()
+is the opposite of
+.BR argz_delete ().
+It inserts the argument
+.I entry
+at position
+.I before
+into the argz vector
+.RI ( *argz ,\  *argz_len )
+and updates
+.I *argz
+and
+.IR *argz_len .
+If
+.I before
+is NULL, then
+.I entry
+will inserted at the end.
+.P
+.BR argz_next ()
+is a function to step through the argz vector.
+If
+.I entry
+is NULL, the first entry is returned.
+Otherwise, the entry
+following is returned.
+It returns NULL if there is no following entry.
+.P
+.BR argz_replace ()
+replaces each occurrence of
+.I str
+with
+.IR with ,
+reallocating argz as necessary.
+If
+.I replace_count
+is non-NULL,
+.I *replace_count
+will be incremented by the number of replacements.
+.P
+.BR argz_stringify ()
+is the opposite of
+.BR argz_create_sep ().
+It transforms the argz vector into a normal string by replacing
+all null bytes (\[aq]\e0\[aq]) except the last by
+.IR sep .
+.SH RETURN VALUE
+All argz functions that do memory allocation have a return type of
+.I error_t
+(an integer type),
+and return 0 for success, and
+.B ENOMEM
+if an allocation error occurs.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR argz_add (),
+.BR argz_add_sep (),
+.BR argz_append (),
+.BR argz_count (),
+.BR argz_create (),
+.BR argz_create_sep (),
+.BR argz_delete (),
+.BR argz_extract (),
+.BR argz_insert (),
+.BR argz_next (),
+.BR argz_replace (),
+.BR argz_stringify ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH BUGS
+Argz vectors without a terminating null byte may lead to
+Segmentation Faults.
+.SH SEE ALSO
+.BR envz_add (3)
diff --git a/man/man3/argz_add_sep.3 b/man/man3/argz_add_sep.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_add_sep.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_append.3 b/man/man3/argz_append.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_append.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_count.3 b/man/man3/argz_count.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_count.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_create.3 b/man/man3/argz_create.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_create.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_create_sep.3 b/man/man3/argz_create_sep.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_create_sep.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_delete.3 b/man/man3/argz_delete.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_delete.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_extract.3 b/man/man3/argz_extract.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_extract.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_insert.3 b/man/man3/argz_insert.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_insert.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_next.3 b/man/man3/argz_next.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_next.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_replace.3 b/man/man3/argz_replace.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_replace.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/argz_stringify.3 b/man/man3/argz_stringify.3
new file mode 100644
index 000000000..25a6e267c
--- /dev/null
+++ b/man/man3/argz_stringify.3
@@ -0,0 +1 @@
+.so man3/argz_add.3
diff --git a/man/man3/asctime.3 b/man/man3/asctime.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/asctime.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/asctime_r.3 b/man/man3/asctime_r.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/asctime_r.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/asin.3 b/man/man3/asin.3
new file mode 100644
index 000000000..7d79f2e16
--- /dev/null
+++ b/man/man3/asin.3
@@ -0,0 +1,117 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-25 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH asin 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+asin, asinf, asinl \- arc sine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double asin(double " x );
+.BI "float asinf(float " x );
+.BI "long double asinl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR asinf (),
+.BR asinl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions calculate the principal value of the arc sine of
+.IR x ;
+that is the value whose sine is
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the principal value of the arc sine of
+.I x
+in radians; the return value is in the range [\-pi/2,\ pi/2].
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0),
++0 (\-0) is returned.
+.P
+If
+.I x
+is outside the range [\-1,\ 1],
+a domain error occurs,
+and a NaN is returned.
+.\"
+.\" POSIX.1-2001 documents an optional range error for subnormal x;
+.\" glibc 2.8 does not do this.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is outside the range [\-1,\ 1]
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR asin (),
+.BR asinf (),
+.BR asinl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR acos (3),
+.BR atan (3),
+.BR atan2 (3),
+.BR casin (3),
+.BR cos (3),
+.BR sin (3),
+.BR tan (3)
diff --git a/man/man3/asinf.3 b/man/man3/asinf.3
new file mode 100644
index 000000000..4c88df085
--- /dev/null
+++ b/man/man3/asinf.3
@@ -0,0 +1 @@
+.so man3/asin.3
diff --git a/man/man3/asinh.3 b/man/man3/asinh.3
new file mode 100644
index 000000000..d4b6f36a0
--- /dev/null
+++ b/man/man3/asinh.3
@@ -0,0 +1,109 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH asinh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+asinh, asinhf, asinhl \- inverse hyperbolic sine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double asinh(double " x );
+.BI "float asinhf(float " x );
+.BI "long double asinhl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR asinh ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR asinhf (),
+.BR asinhl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions calculate the inverse hyperbolic sine of
+.IR x ;
+that is the value whose hyperbolic sine is
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the inverse hyperbolic sine of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0), +0 (\-0) is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity),
+positive infinity (negative infinity) is returned.
+.\"
+.\" POSIX.1-2001 documents an optional range error for subnormal x;
+.\" glibc 2.8 does not do this.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR asinh (),
+.BR asinhf (),
+.BR asinhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR acosh (3),
+.BR atanh (3),
+.BR casinh (3),
+.BR cosh (3),
+.BR sinh (3),
+.BR tanh (3)
diff --git a/man/man3/asinhf.3 b/man/man3/asinhf.3
new file mode 100644
index 000000000..93c50342a
--- /dev/null
+++ b/man/man3/asinhf.3
@@ -0,0 +1 @@
+.so man3/asinh.3
diff --git a/man/man3/asinhl.3 b/man/man3/asinhl.3
new file mode 100644
index 000000000..93c50342a
--- /dev/null
+++ b/man/man3/asinhl.3
@@ -0,0 +1 @@
+.so man3/asinh.3
diff --git a/man/man3/asinl.3 b/man/man3/asinl.3
new file mode 100644
index 000000000..4c88df085
--- /dev/null
+++ b/man/man3/asinl.3
@@ -0,0 +1 @@
+.so man3/asin.3
diff --git a/man/man3/asprintf.3 b/man/man3/asprintf.3
new file mode 100644
index 000000000..bd5fcf7fa
--- /dev/null
+++ b/man/man3/asprintf.3
@@ -0,0 +1,70 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Text fragments inspired by Martin Schulze <joey@infodrom.org>.
+.\"
+.TH asprintf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+asprintf, vasprintf \- print to allocated string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <stdio.h>
+.P
+.BI "int asprintf(char **restrict " strp ", const char *restrict " fmt ", ...);"
+.BI "int vasprintf(char **restrict " strp ", const char *restrict " fmt ,
+.BI "              va_list " ap );
+.fi
+.SH DESCRIPTION
+The functions
+.BR asprintf ()
+and
+.BR vasprintf ()
+are analogs of
+.BR sprintf (3)
+and
+.BR vsprintf (3),
+except that they allocate a string large enough to hold the output
+including the terminating null byte (\[aq]\e0\[aq]),
+and return a pointer to it via the first argument.
+This pointer should be passed to
+.BR free (3)
+to release the allocated storage when it is no longer needed.
+.SH RETURN VALUE
+When successful, these functions return the number of bytes printed,
+just like
+.BR sprintf (3).
+If memory allocation wasn't possible, or some other error occurs,
+these functions will return \-1, and the contents of
+.I strp
+are undefined.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR asprintf (),
+.BR vasprintf ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+The FreeBSD implementation sets
+.I strp
+to NULL on error.
+.SH STANDARDS
+GNU, BSD.
+.SH SEE ALSO
+.BR free (3),
+.BR malloc (3),
+.BR printf (3)
diff --git a/man/man3/assert.3 b/man/man3/assert.3
new file mode 100644
index 000000000..daec8d92b
--- /dev/null
+++ b/man/man3/assert.3
@@ -0,0 +1,96 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 21:42:42 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 23:44:11 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Thu Jun  2 23:44:11 2016 by Nikos Mavrogiannopoulos <nmav@redhat.com>
+.TH assert 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+assert \- abort the program if assertion is false
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <assert.h>
+.P
+.BI "void assert(scalar " expression );
+.fi
+.SH DESCRIPTION
+This macro can help programmers find bugs in their programs,
+or handle exceptional cases
+via a crash that will produce limited debugging output.
+.P
+If
+.I expression
+is false (i.e., compares equal to zero),
+.BR assert ()
+prints an error message to standard error
+and terminates the program by calling
+.BR abort (3).
+The error message includes the name of the file and function containing the
+.BR assert ()
+call, the source code line number of the call, and the text of the argument;
+something like:
+.P
+.in +4n
+.EX
+prog: some_file.c:16: some_func: Assertion \`val == 0\[aq] failed.
+.EE
+.in
+.P
+If the macro
+.B NDEBUG
+is defined at the moment
+.I <assert.h>
+was last included, the macro
+.BR assert ()
+generates no code, and hence does nothing at all.
+It is not recommended to define
+.B NDEBUG
+if using
+.BR assert ()
+to detect error conditions since the software
+may behave non-deterministically.
+.SH RETURN VALUE
+No value is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR assert ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, C99, POSIX.1-2001.
+.P
+In C89,
+.I expression
+is required to be of type
+.I int
+and undefined behavior results if it is not, but in C99
+it may have any scalar type.
+.\" See Defect Report 107 for more details.
+.SH BUGS
+.BR assert ()
+is implemented as a macro; if the expression tested has side-effects,
+program behavior will be different depending on whether
+.B NDEBUG
+is defined.
+This may create Heisenbugs which go away when debugging
+is turned on.
+.SH SEE ALSO
+.BR abort (3),
+.BR assert_perror (3),
+.BR exit (3)
diff --git a/man/man3/assert_perror.3 b/man/man3/assert_perror.3
new file mode 100644
index 000000000..4cdd54c6c
--- /dev/null
+++ b/man/man3/assert_perror.3
@@ -0,0 +1,73 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" This replaces an earlier man page written by Walter Harms
+.\" <walter.harms@informatik.uni-oldenburg.de>.
+.\"
+.TH assert_perror 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+assert_perror \- test errnum and abort
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <assert.h>
+.P
+.BI "void assert_perror(int " errnum );
+.fi
+.SH DESCRIPTION
+If the macro
+.B NDEBUG
+was defined at the moment
+.I <assert.h>
+was last included, the macro
+.BR assert_perror ()
+generates no code, and hence does nothing at all.
+Otherwise, the macro
+.BR assert_perror ()
+prints an error message to standard error and terminates the program
+by calling
+.BR abort (3)
+if
+.I errnum
+is nonzero.
+The message contains the filename, function name and
+line number of the macro call, and the output of
+.IR strerror(errnum) .
+.SH RETURN VALUE
+No value is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR assert_perror ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH BUGS
+The purpose of the assert macros is to help programmers find bugs in
+their programs, things that cannot happen unless there was a coding mistake.
+However, with system or library calls the situation is rather different,
+and error returns can happen, and will happen, and should be tested for.
+Not by an assert, where the test goes away when
+.B NDEBUG
+is defined,
+but by proper error handling code.
+Never use this macro.
+.SH SEE ALSO
+.BR abort (3),
+.BR assert (3),
+.BR exit (3),
+.BR strerror (3)
diff --git a/man/man3/atan.3 b/man/man3/atan.3
new file mode 100644
index 000000000..177968a91
--- /dev/null
+++ b/man/man3/atan.3
@@ -0,0 +1,103 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH atan 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+atan, atanf, atanl \- arc tangent function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double atan(double " x );
+.BI "float atanf(float " x );
+.BI "long double atanl(long double " x );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR atanf (),
+.BR atanl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions calculate the principal value of the arc tangent of
+.IR x ;
+that is the value whose tangent is
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the principal value of the arc tangent of
+.I x
+in radians; the return value is in the range [\-pi/2,\ pi/2].
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0),
++0 (\-0) is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity), +pi/2 (\-pi/2) is returned.
+.\"
+.\" POSIX.1-2001 documents an optional range error for subnormal x;
+.\" glibc 2.8 does not do this.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR atan (),
+.BR atanf (),
+.BR atanl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR acos (3),
+.BR asin (3),
+.BR atan2 (3),
+.BR carg (3),
+.BR catan (3),
+.BR cos (3),
+.BR sin (3),
+.BR tan (3)
diff --git a/man/man3/atan2.3 b/man/man3/atan2.3
new file mode 100644
index 000000000..f0df976fa
--- /dev/null
+++ b/man/man3/atan2.3
@@ -0,0 +1,174 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH atan2 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+atan2, atan2f, atan2l \- arc tangent function of two variables
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double atan2(double " y ", double " x );
+.BI "float atan2f(float " y ", float " x );
+.BI "long double atan2l(long double " y ", long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR atan2f (),
+.BR atan2l ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions calculate the principal value of the arc tangent of
+.IR y/x ,
+using the signs of the two arguments to determine
+the quadrant of the result.
+.SH RETURN VALUE
+On success, these functions return the principal value of the arc tangent of
+.I y/x
+in radians; the return value is in the range [\-pi,\ pi].
+.P
+If
+.I y
+is +0 (\-0) and
+.I x
+is less than 0, +pi (\-pi) is returned.
+.P
+If
+.I y
+is +0 (\-0) and
+.I x
+is greater than 0, +0 (\-0) is returned.
+.P
+If
+.I y
+is less than 0 and
+.I x
+is +0 or \-0, \-pi/2 is returned.
+.P
+If
+.I y
+is greater than 0 and
+.I x
+is +0 or \-0, pi/2 is returned.
+.P
+.\" POSIX.1 says:
+.\" If
+.\" .I x
+.\" is 0, a pole error shall not occur.
+.\"
+If either
+.I x
+or
+.I y
+is NaN, a NaN is returned.
+.P
+.\" POSIX.1 says:
+.\" If the result underflows, a range error may occur and
+.\" .I y/x
+.\" should be returned.
+.\"
+If
+.I y
+is +0 (\-0) and
+.I x
+is \-0, +pi (\-pi) is returned.
+.P
+If
+.I y
+is +0 (\-0) and
+.I x
+is +0, +0 (\-0) is returned.
+.P
+If
+.I y
+is a finite value greater (less) than 0, and
+.I x
+is negative infinity, +pi (\-pi) is returned.
+.P
+If
+.I y
+is a finite value greater (less) than 0, and
+.I x
+is positive infinity, +0 (\-0) is returned.
+.P
+If
+.I y
+is positive infinity (negative infinity), and
+.I x
+is finite,
+pi/2 (\-pi/2) is returned.
+.P
+If
+.I y
+is positive infinity (negative infinity) and
+.I x
+is negative infinity, +3*pi/4 (\-3*pi/4) is returned.
+.P
+If
+.I y
+is positive infinity (negative infinity) and
+.I x
+is positive infinity, +pi/4 (\-pi/4) is returned.
+.\"
+.\" POSIX.1 says:
+.\" If both arguments are 0, a domain error shall not occur.
+.SH ERRORS
+No errors occur.
+.\" POSIX.1 documents an optional underflow error
+.\" glibc 2.8 does not do this.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR atan2 (),
+.BR atan2f (),
+.BR atan2l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR acos (3),
+.BR asin (3),
+.BR atan (3),
+.BR carg (3),
+.BR cos (3),
+.BR sin (3),
+.BR tan (3)
diff --git a/man/man3/atan2f.3 b/man/man3/atan2f.3
new file mode 100644
index 000000000..e445b12b6
--- /dev/null
+++ b/man/man3/atan2f.3
@@ -0,0 +1 @@
+.so man3/atan2.3
diff --git a/man/man3/atan2l.3 b/man/man3/atan2l.3
new file mode 100644
index 000000000..e445b12b6
--- /dev/null
+++ b/man/man3/atan2l.3
@@ -0,0 +1 @@
+.so man3/atan2.3
diff --git a/man/man3/atanf.3 b/man/man3/atanf.3
new file mode 100644
index 000000000..784b32ab9
--- /dev/null
+++ b/man/man3/atanf.3
@@ -0,0 +1 @@
+.so man3/atan.3
diff --git a/man/man3/atanh.3 b/man/man3/atanh.3
new file mode 100644
index 000000000..136a501b7
--- /dev/null
+++ b/man/man3/atanh.3
@@ -0,0 +1,154 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH atanh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+atanh, atanhf, atanhl \- inverse hyperbolic tangent function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double atanh(double " x );
+.BI "float atanhf(float " x );
+.BI "long double atanhl(long double " x );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR atanh ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR atanhf (),
+.BR atanhl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions calculate the inverse hyperbolic tangent of
+.IR x ;
+that is the value whose hyperbolic tangent is
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the inverse hyperbolic tangent of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0), +0 (\-0) is returned.
+.P
+If
+.I x
+is +1 or \-1,
+a pole error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the mathematically correct sign.
+.P
+If the absolute value of
+.I x
+is greater than 1,
+a domain error occurs,
+and a NaN is returned.
+.\"
+.\" POSIX.1-2001 documents an optional range error for subnormal x;
+.\" glibc 2.8 does not do this.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP less than \-1 or greater than +1
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Pole error: \fIx\fP is +1 or \-1
+.I errno
+is set to
+.B ERANGE
+(but see BUGS).
+A divide-by-zero floating-point exception
+.RB ( FE_DIVBYZERO )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR atanh (),
+.BR atanhf (),
+.BR atanhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH BUGS
+In glibc 2.9 and earlier,
+.\" Bug: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6759
+.\" This can be seen in sysdeps/ieee754/k_standard.c
+when a pole error occurs,
+.I errno
+is set to
+.B EDOM
+instead of the POSIX-mandated
+.BR ERANGE .
+Since glibc 2.10, glibc does the right thing.
+.SH SEE ALSO
+.BR acosh (3),
+.BR asinh (3),
+.BR catanh (3),
+.BR cosh (3),
+.BR sinh (3),
+.BR tanh (3)
diff --git a/man/man3/atanhf.3 b/man/man3/atanhf.3
new file mode 100644
index 000000000..225a33928
--- /dev/null
+++ b/man/man3/atanhf.3
@@ -0,0 +1 @@
+.so man3/atanh.3
diff --git a/man/man3/atanhl.3 b/man/man3/atanhl.3
new file mode 100644
index 000000000..225a33928
--- /dev/null
+++ b/man/man3/atanhl.3
@@ -0,0 +1 @@
+.so man3/atanh.3
diff --git a/man/man3/atanl.3 b/man/man3/atanl.3
new file mode 100644
index 000000000..784b32ab9
--- /dev/null
+++ b/man/man3/atanl.3
@@ -0,0 +1 @@
+.so man3/atan.3
diff --git a/man/man3/atexit.3 b/man/man3/atexit.3
new file mode 100644
index 000000000..88f2817b8
--- /dev/null
+++ b/man/man3/atexit.3
@@ -0,0 +1,169 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-03-29, David Metcalfe
+.\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
+.\" Modified 2003-10-25, Walter Harms
+.\"
+.TH atexit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+atexit \- register a function to be called at normal process termination
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int atexit(void (*" function )(void));
+.fi
+.SH DESCRIPTION
+The
+.BR atexit ()
+function registers the given
+.I function
+to be
+called at normal process termination, either via
+.BR exit (3)
+or via return from the program's
+.IR main ().
+Functions so registered are called in
+the reverse order of their registration; no arguments are passed.
+.P
+The same function may be registered multiple times:
+it is called once for each registration.
+.P
+POSIX.1 requires that an implementation allow at least
+.\" POSIX.1-2001, POSIX.1-2008
+.B ATEXIT_MAX
+(32) such functions to be registered.
+The actual limit supported by an implementation can be obtained using
+.BR sysconf (3).
+.P
+When a child process is created via
+.BR fork (2),
+it inherits copies of its parent's registrations.
+Upon a successful call to one of the
+.BR exec (3)
+functions,
+all registrations are removed.
+.SH RETURN VALUE
+The
+.BR atexit ()
+function returns the value 0 if successful; otherwise
+it returns a nonzero value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR atexit ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+POSIX.1 says that the result of calling
+.\" POSIX.1-2001, POSIX.1-2008
+.BR exit (3)
+more than once (i.e., calling
+.BR exit (3)
+within a function registered using
+.BR atexit ())
+is undefined.
+On some systems (but not Linux), this can result in an infinite recursion;
+.\" This can happen on OpenBSD 4.2 for example, and is documented
+.\" as occurring on FreeBSD as well.
+.\" glibc does "the Right Thing" -- invocation of the remaining
+.\" exit handlers carries on as normal.
+portable programs should not invoke
+.BR exit (3)
+inside a function registered using
+.BR atexit ().
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, C99, SVr4, 4.3BSD.
+.SH NOTES
+Functions registered using
+.BR atexit ()
+(and
+.BR on_exit (3))
+are not called if a process terminates abnormally because
+of the delivery of a signal.
+.P
+If one of the registered functions calls
+.BR _exit (2),
+then any remaining functions are not invoked,
+and the other process termination steps performed by
+.BR exit (3)
+are not performed.
+.P
+The
+.BR atexit ()
+and
+.BR on_exit (3)
+functions register functions on the same list:
+at normal process termination,
+the registered functions are invoked in reverse order
+of their registration by these two functions.
+.P
+According to POSIX.1, the result is undefined if
+.BR longjmp (3)
+is used to terminate execution of one of the functions registered using
+.BR atexit ().
+.\" In glibc, things seem to be handled okay
+.SS Linux notes
+Since glibc 2.2.3,
+.BR atexit ()
+(and
+.BR on_exit (3))
+can be used within a shared library to establish functions
+that are called when the shared library is unloaded.
+.SH EXAMPLES
+.\" SRC BEGIN (atexit.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+void
+bye(void)
+{
+    printf("That was all, folks\en");
+}
+\&
+int
+main(void)
+{
+    long a;
+    int i;
+\&
+    a = sysconf(_SC_ATEXIT_MAX);
+    printf("ATEXIT_MAX = %ld\en", a);
+\&
+    i = atexit(bye);
+    if (i != 0) {
+        fprintf(stderr, "cannot set exit function\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR _exit (2),
+.BR dlopen (3),
+.BR exit (3),
+.BR on_exit (3)
diff --git a/man/man3/atof.3 b/man/man3/atof.3
new file mode 100644
index 000000000..cc5323505
--- /dev/null
+++ b/man/man3/atof.3
@@ -0,0 +1,67 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Mon Mar 29 22:39:24 1993, David Metcalfe
+.\" Modified Sat Jul 24 21:39:22 1993, Rik Faith (faith@cs.unc.edu)
+.TH atof 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+atof \- convert a string to a double
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "double atof(const char *" nptr );
+.fi
+.SH DESCRIPTION
+The
+.BR atof ()
+function converts the initial portion of the string
+pointed to by \fInptr\fP to
+.IR double .
+The behavior is the same as
+.P
+.in +4n
+.EX
+strtod(nptr, NULL);
+.EE
+.in
+.P
+except that
+.BR atof ()
+does not detect errors.
+.SH RETURN VALUE
+The converted value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR atof ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, C99, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR atoi (3),
+.BR atol (3),
+.BR strfromd (3),
+.BR strtod (3),
+.BR strtol (3),
+.BR strtoul (3)
diff --git a/man/man3/atoi.3 b/man/man3/atoi.3
new file mode 100644
index 000000000..f5fb5d0e1
--- /dev/null
+++ b/man/man3/atoi.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Mon Mar 29 22:39:41 1993, David Metcalfe
+.\" Modified Sat Jul 24 21:38:42 1993, Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Dec 17 18:35:06 2000, Joseph S. Myers
+.\"
+.TH atoi 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+atoi, atol, atoll \- convert a string to an integer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int atoi(const char *" nptr );
+.BI "long atol(const char *" nptr );
+.BI "long long atoll(const char *" nptr );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR atoll ():
+.nf
+    _ISOC99_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR atoi ()
+function converts the initial portion of the string
+pointed to by \fInptr\fP to
+.IR int .
+The behavior is the same as
+.P
+.in +4n
+.EX
+strtol(nptr, NULL, 10);
+.EE
+.in
+.P
+except that
+.BR atoi ()
+does not detect errors.
+.P
+The
+.BR atol ()
+and
+.BR atoll ()
+functions behave the same as
+.BR atoi (),
+except that they convert the initial portion of the
+string to their return type of \fIlong\fP or \fIlong long\fP.
+.SH RETURN VALUE
+The converted value or 0 on error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR atoi (),
+.BR atol (),
+.BR atoll ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+POSIX.1 leaves the return value of
+.BR atoi ()
+on error unspecified.
+On glibc, musl libc, and uClibc, 0 is returned on error.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001, SVr4, 4.3BSD.
+.P
+C89 and
+POSIX.1-1996 include the functions
+.BR atoi ()
+and
+.BR atol ()
+only.
+.\" .SH NOTES
+.\" Linux libc provided
+.\" .BR atoq ()
+.\" as an obsolete name for
+.\" .BR atoll ();
+.\" .BR atoq ()
+.\" is not provided by glibc.
+.\" The
+.\" .BR atoll ()
+.\" function is present since glibc 2.0.2, but
+.\" not in libc4 or libc5.
+.SH BUGS
+.I errno
+is not set on error so there is no way to distinguish between 0 as an
+error and as the converted value.
+No checks for overflow or underflow are done.
+Only base-10 input can be converted.
+It is recommended to instead use the
+.BR strtol ()
+and
+.BR strtoul ()
+family of functions in new programs.
+.SH SEE ALSO
+.BR atof (3),
+.BR strtod (3),
+.BR strtol (3),
+.BR strtoul (3)
diff --git a/man/man3/atol.3 b/man/man3/atol.3
new file mode 100644
index 000000000..51f084f16
--- /dev/null
+++ b/man/man3/atol.3
@@ -0,0 +1 @@
+.so man3/atoi.3
diff --git a/man/man3/atoll.3 b/man/man3/atoll.3
new file mode 100644
index 000000000..51f084f16
--- /dev/null
+++ b/man/man3/atoll.3
@@ -0,0 +1 @@
+.so man3/atoi.3
diff --git a/man/man3/atoq.3 b/man/man3/atoq.3
new file mode 100644
index 000000000..51f084f16
--- /dev/null
+++ b/man/man3/atoq.3
@@ -0,0 +1 @@
+.so man3/atoi.3
diff --git a/man/man3/auth_destroy.3 b/man/man3/auth_destroy.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/auth_destroy.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/authnone_create.3 b/man/man3/authnone_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/authnone_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/authunix_create.3 b/man/man3/authunix_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/authunix_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/authunix_create_default.3 b/man/man3/authunix_create_default.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/authunix_create_default.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/backtrace.3 b/man/man3/backtrace.3
new file mode 100644
index 000000000..4875da31f
--- /dev/null
+++ b/man/man3/backtrace.3
@@ -0,0 +1,283 @@
+'\" t
+.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" drawing on material by Justin Pryzby <pryzbyj@justinpryzby.com>
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Permission is hereby granted, free of charge, to any person obtaining
+.\" a copy of this software and associated documentation files (the
+.\" "Software"), to deal in the Software without restriction, including
+.\" without limitation the rights to use, copy, modify, merge, publish,
+.\" distribute, sublicense, and/or sell copies of the Software, and to
+.\" permit persons to whom the Software is furnished to do so, subject to
+.\" the following conditions:
+.\"
+.\" The above copyright notice and this permission notice shall be
+.\" included in all copies or substantial portions of the Software.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+.\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+.\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+.\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+.\" %%%LICENSE_END
+.\"
+.\" References:
+.\"   glibc manual and source
+.TH backtrace 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+backtrace, backtrace_symbols, backtrace_symbols_fd \- support
+for application self-debugging
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <execinfo.h>
+.P
+.BI "int backtrace(void *" buffer [. size "], int " size );
+.P
+.BI "char **backtrace_symbols(void *const " buffer [. size "], int " size );
+.BI "void backtrace_symbols_fd(void *const " buffer [. size "], int " size ", \
+int " fd );
+.fi
+.SH DESCRIPTION
+.BR backtrace ()
+returns a backtrace for the calling program,
+in the array pointed to by
+.IR buffer .
+A backtrace is the series of currently active function calls for
+the program.
+Each item in the array pointed to by
+.I buffer
+is of type
+.IR "void\ *" ,
+and is the return address from
+the corresponding stack frame.
+The
+.I size
+argument specifies the maximum number of addresses
+that can be stored in
+.IR buffer .
+If the backtrace is larger than
+.IR size ,
+then the addresses corresponding to the
+.I size
+most recent function calls are returned;
+to obtain the complete backtrace, make sure that
+.I buffer
+and
+.I size
+are large enough.
+.P
+Given the set of addresses returned by
+.BR backtrace ()
+in
+.IR buffer ,
+.BR backtrace_symbols ()
+translates the addresses into an array of strings that describe
+the addresses symbolically.
+The
+.I size
+argument specifies the number of addresses in
+.IR buffer .
+The symbolic representation of each address consists of the function name
+(if this can be determined), a hexadecimal offset into the function,
+and the actual return address (in hexadecimal).
+The address of the array of string pointers is returned
+as the function result of
+.BR backtrace_symbols ().
+This array is
+.BR malloc (3)ed
+by
+.BR backtrace_symbols (),
+and must be freed by the caller.
+(The strings pointed to by the array of pointers
+need not and should not be freed.)
+.P
+.BR backtrace_symbols_fd ()
+takes the same
+.I buffer
+and
+.I size
+arguments as
+.BR backtrace_symbols (),
+but instead of returning an array of strings to the caller,
+it writes the strings, one per line, to the file descriptor
+.IR fd .
+.BR backtrace_symbols_fd ()
+does not call
+.BR malloc (3),
+and so can be employed in situations where the latter function might
+fail, but see NOTES.
+.SH RETURN VALUE
+.BR backtrace ()
+returns the number of addresses returned in
+.IR buffer ,
+which is not greater than
+.IR size .
+If the return value is less than
+.IR size ,
+then the full backtrace was stored; if it is equal to
+.IR size ,
+then it may have been truncated, in which case the addresses of the
+oldest stack frames are not returned.
+.P
+On success,
+.BR backtrace_symbols ()
+returns a pointer to the array
+.BR malloc (3)ed
+by the call;
+on error, NULL is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR backtrace (),
+.BR backtrace_symbols (),
+.BR backtrace_symbols_fd ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.SH NOTES
+These functions make some assumptions about how a function's return
+address is stored on the stack.
+Note the following:
+.IP \[bu] 3
+Omission of the frame pointers (as
+implied by any of
+.BR gcc (1)'s
+nonzero optimization levels) may cause these assumptions to be
+violated.
+.IP \[bu]
+Inlined functions do not have stack frames.
+.IP \[bu]
+Tail-call optimization causes one stack frame to replace another.
+.IP \[bu]
+.BR backtrace ()
+and
+.BR backtrace_symbols_fd ()
+don't call
+.BR malloc ()
+explicitly, but they are part of
+.IR libgcc ,
+which gets loaded dynamically when first used.
+Dynamic loading usually triggers a call to
+.BR malloc (3).
+If you need certain calls to these two functions to not allocate memory
+(in signal handlers, for example), you need to make sure
+.I libgcc
+is loaded beforehand.
+.P
+The symbol names may be unavailable without the use of special linker
+options.
+For systems using the GNU linker, it is necessary to use the
+.I \-rdynamic
+linker option.
+Note that names of "static" functions are not exposed,
+and won't be available in the backtrace.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR backtrace ()
+and
+.BR backtrace_symbols ().
+The following shell session shows what we might see when running the
+program:
+.P
+.in +4n
+.EX
+.RB "$" " cc \-rdynamic prog.c \-o prog"
+.RB "$" " ./prog 3"
+backtrace() returned 8 addresses
+\&./prog(myfunc3+0x5c) [0x80487f0]
+\&./prog [0x8048871]
+\&./prog(myfunc+0x21) [0x8048894]
+\&./prog(myfunc+0x1a) [0x804888d]
+\&./prog(myfunc+0x1a) [0x804888d]
+\&./prog(main+0x65) [0x80488fb]
+\&/lib/libc.so.6(__libc_start_main+0xdc) [0xb7e38f9c]
+\&./prog [0x8048711]
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (backtrace.c)
+.EX
+#include <execinfo.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define BT_BUF_SIZE 100
+\&
+void
+myfunc3(void)
+{
+    int nptrs;
+    void *buffer[BT_BUF_SIZE];
+    char **strings;
+\&
+    nptrs = backtrace(buffer, BT_BUF_SIZE);
+    printf("backtrace() returned %d addresses\en", nptrs);
+\&
+    /* The call backtrace_symbols_fd(buffer, nptrs, STDOUT_FILENO)
+       would produce similar output to the following: */
+\&
+    strings = backtrace_symbols(buffer, nptrs);
+    if (strings == NULL) {
+        perror("backtrace_symbols");
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (size_t j = 0; j < nptrs; j++)
+        printf("%s\en", strings[j]);
+\&
+    free(strings);
+}
+\&
+static void   /* "static" means don\[aq]t export the symbol... */
+myfunc2(void)
+{
+    myfunc3();
+}
+\&
+void
+myfunc(int ncalls)
+{
+    if (ncalls > 1)
+        myfunc(ncalls \- 1);
+    else
+        myfunc2();
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    if (argc != 2) {
+        fprintf(stderr, "%s num\-calls\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    myfunc(atoi(argv[1]));
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR addr2line (1),
+.BR gcc (1),
+.BR gdb (1),
+.BR ld (1),
+.BR dlopen (3),
+.BR malloc (3)
diff --git a/man/man3/backtrace_symbols.3 b/man/man3/backtrace_symbols.3
new file mode 100644
index 000000000..936a6b9f6
--- /dev/null
+++ b/man/man3/backtrace_symbols.3
@@ -0,0 +1 @@
+.so man3/backtrace.3
diff --git a/man/man3/backtrace_symbols_fd.3 b/man/man3/backtrace_symbols_fd.3
new file mode 100644
index 000000000..936a6b9f6
--- /dev/null
+++ b/man/man3/backtrace_symbols_fd.3
@@ -0,0 +1 @@
+.so man3/backtrace.3
diff --git a/man/man3/basename.3 b/man/man3/basename.3
new file mode 100644
index 000000000..2702a05f8
--- /dev/null
+++ b/man/man3/basename.3
@@ -0,0 +1,187 @@
+'\" t
+.\" Copyright (c) 2000 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created, 14 Dec 2000 by Michael Kerrisk
+.\"
+.TH basename 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+basename, dirname \- parse pathname components
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <libgen.h>
+.P
+.BI "char *dirname(char *" path );
+.BI "char *basename(char *" path );
+.fi
+.SH DESCRIPTION
+Warning: there are two different functions
+.BR basename ();
+see below.
+.P
+The functions
+.BR dirname ()
+and
+.BR basename ()
+break a null-terminated pathname string into directory
+and filename components.
+In the usual case,
+.BR dirname ()
+returns the string up to, but not including, the final \[aq]/\[aq], and
+.BR basename ()
+returns the component following the final \[aq]/\[aq].
+Trailing \[aq]/\[aq] characters are not counted as part of the pathname.
+.P
+If
+.I path
+does not contain a slash,
+.BR dirname ()
+returns the string "." while
+.BR basename ()
+returns a copy of
+.IR path .
+If
+.I path
+is the string "/", then both
+.BR dirname ()
+and
+.BR basename ()
+return the string "/".
+If
+.I path
+is a null pointer or points to an empty string, then both
+.BR dirname ()
+and
+.BR basename ()
+return the string ".".
+.P
+Concatenating the string returned by
+.BR dirname (),
+a "/", and the string returned by
+.BR basename ()
+yields a complete pathname.
+.P
+Both
+.BR dirname ()
+and
+.BR basename ()
+may modify the contents of
+.IR path ,
+so it may be desirable to pass a copy when calling one of
+these functions.
+.P
+These functions may return pointers to statically allocated memory
+which may be overwritten by subsequent calls.
+Alternatively, they may return a pointer to some part of
+.IR path ,
+so that the string referred to by
+.I path
+should not be modified or freed until the pointer returned by
+the function is no longer required.
+.P
+The following list of examples (taken from SUSv2)
+shows the strings returned by
+.BR dirname ()
+and
+.BR basename ()
+for different paths:
+.RS
+.TS
+lb lb lb
+l l l l.
+path    	dirname	basename
+/usr/lib	/usr	lib
+/usr/   	/	usr
+usr     	.	usr
+/       	/	/
+\&.       	.	.
+\&..      	.	..
+.TE
+.RE
+.SH RETURN VALUE
+Both
+.BR dirname ()
+and
+.BR basename ()
+return pointers to null-terminated strings.
+(Do not pass these pointers to
+.BR free (3).)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR basename (),
+.BR dirname ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+There are two different versions of
+.BR basename ()
+- the POSIX version described above, and the GNU version, which one gets
+after
+.P
+.in +4n
+.EX
+.BR "    #define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B "    #include <string.h>"
+.EE
+.in
+.P
+The GNU version never modifies its argument, and returns the
+empty string when
+.I path
+has a trailing slash, and in particular also when it is "/".
+There is no GNU version of
+.BR dirname ().
+.P
+With glibc, one gets the POSIX version of
+.BR basename ()
+when
+.I <libgen.h>
+is included, and the GNU version otherwise.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH BUGS
+In the glibc implementation,
+the POSIX versions of these functions modify the
+.I path
+argument, and segfault when called with a static string
+such as "/usr/".
+.P
+Before glibc 2.2.1, the glibc version of
+.BR dirname ()
+did not correctly handle pathnames with trailing \[aq]/\[aq] characters,
+and generated a segfault if given a NULL argument.
+.SH EXAMPLES
+The following code snippet demonstrates the use of
+.BR basename ()
+and
+.BR dirname ():
+.in +4n
+.EX
+char *dirc, *basec, *bname, *dname;
+char *path = "/etc/passwd";
+\&
+dirc = strdup(path);
+basec = strdup(path);
+dname = dirname(dirc);
+bname = basename(basec);
+printf("dirname=%s, basename=%s\en", dname, bname);
+.EE
+.in
+.SH SEE ALSO
+.BR basename (1),
+.BR dirname (1)
diff --git a/man/man3/bcmp.3 b/man/man3/bcmp.3
new file mode 100644
index 000000000..c52b8f75b
--- /dev/null
+++ b/man/man3/bcmp.3
@@ -0,0 +1,30 @@
+.\" Copyright 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH bcmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bcmp \- compare byte sequences
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <strings.h>
+.P
+.BI "[[deprecated]] int bcmp(const void " s1 [. n "], const void " s2 [. n "], \
+size_t " n );
+.fi
+.SH DESCRIPTION
+.BR bcmp ()
+is identical to
+.BR memcmp (3);
+use the latter instead.
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD.
+Marked as LEGACY in POSIX.1-2001;
+removed in POSIX.1-2008.
+.SH SEE ALSO
+.BR memcmp (3)
diff --git a/man/man3/bcopy.3 b/man/man3/bcopy.3
new file mode 100644
index 000000000..96ca89f37
--- /dev/null
+++ b/man/man3/bcopy.3
@@ -0,0 +1,76 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified Sun Feb 26 14:52:00 1995 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 23:48:10 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" "
+.TH bcopy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bcopy \- copy byte sequence
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <strings.h>
+.P
+.BI "[[deprecated]] void bcopy(const void " src [. n "], void " dest [. n "], \
+size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR bcopy ()
+function copies
+.I n
+bytes from
+.I src
+to
+.IR dest .
+The result is correct, even when both areas overlap.
+.SH RETURN VALUE
+None.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR bcopy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD.
+.P
+Marked as LEGACY in POSIX.1-2001: use
+.BR memcpy (3)
+or
+.BR memmove (3)
+in new programs.
+Note that the first two arguments
+are interchanged for
+.BR memcpy (3)
+and
+.BR memmove (3).
+POSIX.1-2008 removes the specification of
+.BR bcopy ().
+.SH SEE ALSO
+.BR bstring (3),
+.BR memccpy (3),
+.BR memcpy (3),
+.BR memmove (3),
+.BR strcpy (3),
+.BR strncpy (3)
diff --git a/man/man3/be16toh.3 b/man/man3/be16toh.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/be16toh.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/be32toh.3 b/man/man3/be32toh.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/be32toh.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/be64toh.3 b/man/man3/be64toh.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/be64toh.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/bindresvport.3 b/man/man3/bindresvport.3
new file mode 100644
index 000000000..c17f586b3
--- /dev/null
+++ b/man/man3/bindresvport.3
@@ -0,0 +1,116 @@
+'\" t
+.\" Copyright (C) 2007, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2007-05-31, mtk: Rewrite and substantial additional text.
+.\" 2008-12-03, mtk: Rewrote some pieces and fixed some errors
+.\"
+.TH bindresvport 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bindresvport \- bind a socket to a privileged IP port
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <netinet/in.h>
+.P
+.BI "int bindresvport(int " sockfd ", struct sockaddr_in *" sin );
+.fi
+.SH DESCRIPTION
+.BR bindresvport ()
+is used to bind the socket referred to by the
+file descriptor
+.I sockfd
+to a privileged anonymous IP port,
+that is, a port number arbitrarily selected from the range 512 to 1023.
+.\" glibc actually starts searching with a port # in the range 600 to 1023
+.P
+If the
+.BR bind (2)
+performed by
+.BR bindresvport ()
+is successful, and
+.I sin
+is not NULL, then
+.I sin\->sin_port
+returns the port number actually allocated.
+.P
+.I sin
+can be NULL, in which case
+.I sin\->sin_family
+is implicitly taken to be
+.BR AF_INET .
+However, in this case,
+.BR bindresvport ()
+has no way to return the port number actually allocated.
+(This information can later be obtained using
+.BR getsockname (2).)
+.SH RETURN VALUE
+.BR bindresvport ()
+returns 0 on success; otherwise \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR bindresvport ()
+can fail for any of the same reasons as
+.BR bind (2).
+In addition, the following errors may occur:
+.TP
+.B EACCES
+The calling process was not privileged
+(on Linux: the calling process did not have the
+.B CAP_NET_BIND_SERVICE
+capability in the user namespace governing its network namespace).
+.TP
+.B EADDRINUSE
+All privileged ports are in use.
+.TP
+.BR EAFNOSUPPORT " (" EPFNOSUPPORT " in glibc 2.7 and earlier)"
+.I sin
+is not NULL and
+.I sin\->sin_family
+is not
+.BR AF_INET .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR bindresvport ()
+T}	Thread safety	T{
+.na
+.nh
+glibc\ >=\ 2.17: MT-Safe;
+.\" commit f6da27e53695ad1cc0e2a9490358decbbfdff5e5
+glibc\ <\ 2.17: MT-Unsafe
+T}
+.TE
+.P
+The
+.BR bindresvport ()
+function uses a static variable that was not protected by a lock
+before glibc 2.17, rendering the function MT-Unsafe.
+.SH VERSIONS
+Present on the BSDs, Solaris, and many other systems.
+.SH NOTES
+Unlike some
+.BR bindresvport ()
+implementations,
+the glibc implementation ignores any value that the caller supplies in
+.IR sin\->sin_port .
+.SH STANDARDS
+BSD.
+.SH SEE ALSO
+.BR bind (2),
+.BR getsockname (2)
diff --git a/man/man3/bsd_signal.3 b/man/man3/bsd_signal.3
new file mode 100644
index 000000000..00026fee5
--- /dev/null
+++ b/man/man3/bsd_signal.3
@@ -0,0 +1,112 @@
+'\" t
+.\" Copyright (c) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH bsd_signal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bsd_signal \- signal handling with BSD semantics
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.B typedef void (*sighandler_t)(int);
+.P
+.BI "sighandler_t bsd_signal(int " signum ", sighandler_t " handler );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR bsd_signal ():
+.nf
+    Since glibc 2.26:
+        _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+            && ! (_POSIX_C_SOURCE >= 200809L)
+    glibc 2.25 and earlier:
+        _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR bsd_signal ()
+function takes the same arguments, and performs the same task, as
+.BR signal (2).
+.P
+The difference between the two is that
+.BR bsd_signal ()
+is guaranteed to provide reliable signal semantics, that is:
+a) the disposition of the signal is not reset to the default
+when the handler is invoked;
+b) delivery of further instances of the signal is blocked while
+the signal handler is executing; and
+c) if the handler interrupts a blocking system call,
+then the system call is automatically restarted.
+A portable application cannot rely on
+.BR signal (2)
+to provide these guarantees.
+.SH RETURN VALUE
+The
+.BR bsd_signal ()
+function returns the previous value of the signal handler, or
+.B SIG_ERR
+on error.
+.SH ERRORS
+As for
+.BR signal (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR bsd_signal ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Use of
+.BR bsd_signal ()
+should be avoided; use
+.BR sigaction (2)
+instead.
+.P
+On modern Linux systems,
+.BR bsd_signal ()
+and
+.BR signal (2)
+are equivalent.
+But on older systems,
+.BR signal (2)
+provided unreliable signal semantics; see
+.BR signal (2)
+for details.
+.P
+The use of
+.I sighandler_t
+is a GNU extension;
+this type is defined only if the
+.B _GNU_SOURCE
+feature test macro is defined.
+.SH STANDARDS
+None.
+.SH HISTORY
+4.2BSD, POSIX.1-2001.
+Removed in POSIX.1-2008,
+recommending the use of
+.BR sigaction (2)
+instead.
+.SH SEE ALSO
+.BR sigaction (2),
+.BR signal (2),
+.BR sysv_signal (3),
+.BR signal (7)
diff --git a/man/man3/bsearch.3 b/man/man3/bsearch.3
new file mode 100644
index 000000000..56ba64486
--- /dev/null
+++ b/man/man3/bsearch.3
@@ -0,0 +1,139 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Mon Mar 29 22:41:16 1993, David Metcalfe
+.\" Modified Sat Jul 24 21:35:16 1993, Rik Faith (faith@cs.unc.edu)
+.TH bsearch 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bsearch \- binary search of a sorted array
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "void *bsearch(const void " key [. size "], \
+const void " base [. size " * ." nmemb ],
+.BI "              size_t " nmemb ", size_t " size ,
+.BI "              int (*" compar ")(const void [." size "], \
+const void [." size ]));
+.fi
+.SH DESCRIPTION
+The
+.BR bsearch ()
+function searches an array of
+.I nmemb
+objects,
+the initial member of which is pointed to by
+.IR base ,
+for a member
+that matches the object pointed to by
+.IR key .
+The size of each member
+of the array is specified by
+.IR size .
+.P
+The contents of the array should be in ascending sorted order according
+to the comparison function referenced by
+.IR compar .
+The
+.I compar
+routine is expected to have two arguments which point to the
+.I key
+object and to an array member, in that order, and should return an integer
+less than, equal to, or greater than zero if the
+.I key
+object is found,
+respectively, to be less than, to match, or be greater than the array
+member.
+.SH RETURN VALUE
+The
+.BR bsearch ()
+function returns a pointer to a matching member of the
+array, or NULL if no match is found.
+If there are multiple elements that
+match the key, the element returned is unspecified.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR bsearch ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, C99, SVr4, 4.3BSD.
+.SH EXAMPLES
+The example below first sorts an array of structures using
+.BR qsort (3),
+then retrieves desired elements using
+.BR bsearch ().
+.P
+.\" SRC BEGIN (bsearch.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define ARRAY_SIZE(arr)  (sizeof((arr)) / sizeof((arr)[0]))
+\&
+struct mi {
+    int         nr;
+    const char  *name;
+};
+\&
+static struct mi  months[] = {
+    { 1, "jan" }, { 2, "feb" }, { 3, "mar" }, { 4, "apr" },
+    { 5, "may" }, { 6, "jun" }, { 7, "jul" }, { 8, "aug" },
+    { 9, "sep" }, {10, "oct" }, {11, "nov" }, {12, "dec" }
+};
+\&
+static int
+compmi(const void *m1, const void *m2)
+{
+    const struct mi *mi1 = m1;
+    const struct mi *mi2 = m2;
+\&
+    return strcmp(mi1\->name, mi2\->name);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    qsort(months, ARRAY_SIZE(months), sizeof(months[0]), compmi);
+    for (size_t i = 1; i < argc; i++) {
+        struct mi key;
+        struct mi *res;
+\&
+        key.name = argv[i];
+        res = bsearch(&key, months, ARRAY_SIZE(months),
+                      sizeof(months[0]), compmi);
+        if (res == NULL)
+            printf("\[aq]%s\[aq]: unknown month\en", argv[i]);
+        else
+            printf("%s: month #%d\en", res\->name, res\->nr);
+    }
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR hsearch (3),
+.BR lsearch (3),
+.BR qsort (3),
+.BR tsearch (3)
diff --git a/man/man3/bstring.3 b/man/man3/bstring.3
new file mode 100644
index 000000000..9450b4128
--- /dev/null
+++ b/man/man3/bstring.3
@@ -0,0 +1,76 @@
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-04-12, David Metcalfe
+.\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-01-20, Walter Harms
+.TH bstring 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bcmp, bcopy, bzero, memccpy, memchr, memcmp, memcpy, memfrob, memmem,
+memmove, memset \- byte string operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "int bcmp(const void " s1 [. n "], const void " s2 [. n "], size_t " n );
+.P
+.BI "void bcopy(const void " src [. n "], void " dest [. n "], size_t " n );
+.P
+.BI "void bzero(void " s [. n "], size_t " n );
+.P
+.BI "void *memccpy(void " dest [. n "], const void " src [. n "], int " c ", \
+size_t " n );
+.P
+.BI "void *memchr(const void " s [. n "], int " c ", size_t " n );
+.P
+.BI "int memcmp(const void " s1 [. n "], const void " s2 [. n "], size_t " n );
+.P
+.BI "void *memcpy(void " dest [. n "], const void " src [. n "], size_t " n );
+.P
+.BI "void *memfrob(void " s [. n "], size_t " n );
+.P
+.BI "void *memmem(const void " haystack [. haystacklen "], size_t " haystacklen ,
+.BI "             const void " needle [. needlelen "], size_t " needlelen );
+.P
+.BI "void *memmove(void " dest [. n "], const void " src [. n "], size_t " n );
+.P
+.BI "void *memset(void " s [. n "], int " c ", size_t " n );
+.fi
+.SH DESCRIPTION
+The byte string functions perform operations on strings (byte arrays)
+that are not necessarily null-terminated.
+See the individual man pages
+for descriptions of each function.
+.SH NOTES
+The functions
+.BR bcmp ()
+and
+.BR bcopy ()
+are obsolete.
+Use
+.BR memcmp ()
+and
+.BR memmove ()
+instead.
+.\" The old functions are not even available on some non-GNU/Linux systems.
+.SH SEE ALSO
+.BR bcmp (3),
+.BR bcopy (3),
+.BR bzero (3),
+.BR memccpy (3),
+.BR memchr (3),
+.BR memcmp (3),
+.BR memcpy (3),
+.BR memfrob (3),
+.BR memmem (3),
+.BR memmove (3),
+.BR memset (3),
+.BR string (3)
diff --git a/man/man3/bswap.3 b/man/man3/bswap.3
new file mode 100644
index 000000000..d7bac680c
--- /dev/null
+++ b/man/man3/bswap.3
@@ -0,0 +1,68 @@
+.\" Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH bswap 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bswap_16, bswap_32, bswap_64 \- reverse order of bytes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <byteswap.h>
+.P
+.BI "uint16_t bswap_16(uint16_t " x );
+.BI "uint32_t bswap_32(uint32_t " x );
+.BI "uint64_t bswap_64(uint64_t " x );
+.fi
+.SH DESCRIPTION
+These functions return a value in which the order of the bytes
+in their 2-, 4-, or 8-byte arguments is reversed.
+.SH RETURN VALUE
+These functions return the value of their argument with the bytes reversed.
+.SH ERRORS
+These functions always succeed.
+.SH STANDARDS
+GNU.
+.SH EXAMPLES
+The program below swaps the bytes of the 8-byte integer supplied as
+its command-line argument.
+The following shell session demonstrates the use of the program:
+.P
+.in +4n
+.EX
+$ \fB./a.out 0x0123456789abcdef\fP
+0x123456789abcdef ==> 0xefcdab8967452301
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (bswap.c)
+.EX
+#include <byteswap.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    uint64_t x;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <num>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    x = strtoull(argv[1], NULL, 0);
+    printf("%#" PRIx64 " ==> %#" PRIx64 "\en", x, bswap_64(x));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR byteorder (3),
+.BR endian (3)
diff --git a/man/man3/bswap_16.3 b/man/man3/bswap_16.3
new file mode 100644
index 000000000..15a89ab6f
--- /dev/null
+++ b/man/man3/bswap_16.3
@@ -0,0 +1 @@
+.so man3/bswap.3
diff --git a/man/man3/bswap_32.3 b/man/man3/bswap_32.3
new file mode 100644
index 000000000..15a89ab6f
--- /dev/null
+++ b/man/man3/bswap_32.3
@@ -0,0 +1 @@
+.so man3/bswap.3
diff --git a/man/man3/bswap_64.3 b/man/man3/bswap_64.3
new file mode 100644
index 000000000..15a89ab6f
--- /dev/null
+++ b/man/man3/bswap_64.3
@@ -0,0 +1 @@
+.so man3/bswap.3
diff --git a/man/man3/btowc.3 b/man/man3/btowc.3
new file mode 100644
index 000000000..431f3fe14
--- /dev/null
+++ b/man/man3/btowc.3
@@ -0,0 +1,86 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH btowc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+btowc \- convert single byte to wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wint_t btowc(int " c );
+.fi
+.SH DESCRIPTION
+The
+.BR btowc ()
+function converts \fIc\fP,
+interpreted as a multibyte sequence
+of length 1, starting in the initial shift state, to a wide character and
+returns it.
+If \fIc\fP is
+.B EOF
+or not a valid multibyte sequence of length 1,
+the
+.BR btowc ()
+function returns
+.BR WEOF .
+.SH RETURN VALUE
+The
+.BR btowc ()
+function returns the wide character
+converted from the single byte \fIc\fP.
+If \fIc\fP is
+.B EOF
+or not a valid multibyte sequence of length 1,
+it returns
+.BR WEOF .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR btowc ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH NOTES
+The behavior of
+.BR btowc ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+This function should never be used.
+It does not work for encodings which have
+state, and unnecessarily treats single bytes differently from multibyte
+sequences.
+Use either
+.BR mbtowc (3)
+or the thread-safe
+.BR mbrtowc (3)
+instead.
+.SH SEE ALSO
+.BR mbrtowc (3),
+.BR mbtowc (3),
+.BR wctob (3)
diff --git a/man/man3/btree.3 b/man/man3/btree.3
new file mode 100644
index 000000000..b3ce40c13
--- /dev/null
+++ b/man/man3/btree.3
@@ -0,0 +1,229 @@
+.\" Copyright (c) 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	@(#)btree.3	8.4 (Berkeley) 8/18/94
+.\"
+.TH btree 3 (date) "Linux man-pages (unreleased)"
+.\".UC 7
+.SH NAME
+btree \- btree database access method
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.ft B
+#include <sys/types.h>
+#include <db.h>
+.ft R
+.fi
+.SH DESCRIPTION
+.IR "Note well" :
+This page documents interfaces provided up until glibc 2.1.
+Since glibc 2.2, glibc no longer provides these interfaces.
+Probably, you are looking for the APIs provided by the
+.I libdb
+library instead.
+.P
+The routine
+.BR dbopen (3)
+is the library interface to database files.
+One of the supported file formats is btree files.
+The general description of the database access methods is in
+.BR dbopen (3),
+this manual page describes only the btree-specific information.
+.P
+The btree data structure is a sorted, balanced tree structure storing
+associated key/data pairs.
+.P
+The btree access-method-specific data structure provided to
+.BR dbopen (3)
+is defined in the
+.I <db.h>
+include file as follows:
+.P
+.in +4n
+.EX
+typedef struct {
+    unsigned long flags;
+    unsigned int  cachesize;
+    int           maxkeypage;
+    int           minkeypage;
+    unsigned int  psize;
+    int         (*compare)(const DBT *key1, const DBT *key2);
+    size_t      (*prefix)(const DBT *key1, const DBT *key2);
+    int           lorder;
+} BTREEINFO;
+.EE
+.in
+.P
+The elements of this structure are as follows:
+.TP
+.I flags
+The flag value is specified by ORing any of the following values:
+.RS
+.TP
+.B R_DUP
+Permit duplicate keys in the tree, that is,
+permit insertion if the key to be
+inserted already exists in the tree.
+The default behavior, as described in
+.BR dbopen (3),
+is to overwrite a matching key when inserting a new key or to fail if
+the
+.B R_NOOVERWRITE
+flag is specified.
+The
+.B R_DUP
+flag is overridden by the
+.B R_NOOVERWRITE
+flag, and if the
+.B R_NOOVERWRITE
+flag is specified, attempts to insert duplicate keys into
+the tree will fail.
+.IP
+If the database contains duplicate keys, the order of retrieval of
+key/data pairs is undefined if the
+.I get
+routine is used, however,
+.I seq
+routine calls with the
+.B R_CURSOR
+flag set will always return the logical
+"first" of any group of duplicate keys.
+.RE
+.TP
+.I cachesize
+A suggested maximum size (in bytes) of the memory cache.
+This value is
+.I only
+advisory, and the access method will allocate more memory rather than fail.
+Since every search examines the root page of the tree, caching the most
+recently used pages substantially improves access time.
+In addition, physical writes are delayed as long as possible, so a moderate
+cache can reduce the number of I/O operations significantly.
+Obviously, using a cache increases (but only increases) the likelihood of
+corruption or lost data if the system crashes while a tree is being modified.
+If
+.I cachesize
+is 0 (no size is specified), a default cache is used.
+.TP
+.I maxkeypage
+The maximum number of keys which will be stored on any single page.
+Not currently implemented.
+.\" The maximum number of keys which will be stored on any single page.
+.\" Because of the way the btree data structure works,
+.\" .I maxkeypage
+.\" must always be greater than or equal to 2.
+.\" If
+.\" .I maxkeypage
+.\" is 0 (no maximum number of keys is specified), the page fill factor is
+.\" made as large as possible (which is almost invariably what is wanted).
+.TP
+.I minkeypage
+The minimum number of keys which will be stored on any single page.
+This value is used to determine which keys will be stored on overflow
+pages, that is, if a key or data item is longer than the pagesize divided
+by the minkeypage value, it will be stored on overflow pages instead
+of in the page itself.
+If
+.I minkeypage
+is 0 (no minimum number of keys is specified), a value of 2 is used.
+.TP
+.I psize
+Page size is the size (in bytes) of the pages used for nodes in the tree.
+The minimum page size is 512 bytes and the maximum page size is 64\ KiB.
+If
+.I psize
+is 0 (no page size is specified), a page size is chosen based on the
+underlying filesystem I/O block size.
+.TP
+.I compare
+Compare is the key comparison function.
+It must return an integer less than, equal to, or greater than zero if the
+first key argument is considered to be respectively less than, equal to,
+or greater than the second key argument.
+The same comparison function must be used on a given tree every time it
+is opened.
+If
+.I compare
+is NULL (no comparison function is specified), the keys are compared
+lexically, with shorter keys considered less than longer keys.
+.TP
+.I prefix
+Prefix is the prefix comparison function.
+If specified, this routine must return the number of bytes of the second key
+argument which are necessary to determine that it is greater than the first
+key argument.
+If the keys are equal, the key length should be returned.
+Note, the usefulness of this routine is very data-dependent, but, in some
+data sets can produce significantly reduced tree sizes and search times.
+If
+.I prefix
+is NULL (no prefix function is specified),
+.I and
+no comparison function is specified, a default lexical comparison routine
+is used.
+If
+.I prefix
+is NULL and a comparison routine is specified, no prefix comparison is
+done.
+.TP
+.I lorder
+The byte order for integers in the stored database metadata.
+The number should represent the order as an integer; for example,
+big endian order would be the number 4,321.
+If
+.I lorder
+is 0 (no order is specified), the current host order is used.
+.P
+If the file already exists (and the
+.B O_TRUNC
+flag is not specified), the
+values specified for the arguments
+.IR flags ,
+.IR lorder ,
+and
+.I psize
+are ignored
+in favor of the values used when the tree was created.
+.P
+Forward sequential scans of a tree are from the least key to the greatest.
+.P
+Space freed up by deleting key/data pairs from the tree is never reclaimed,
+although it is normally made available for reuse.
+This means that the btree storage structure is grow-only.
+The only solutions are to avoid excessive deletions, or to create a fresh
+tree periodically from a scan of an existing one.
+.P
+Searches, insertions, and deletions in a btree will all complete in
+O lg base N where base is the average fill factor.
+Often, inserting ordered data into btrees results in a low fill factor.
+This implementation has been modified to make ordered insertion the best
+case, resulting in a much better than normal page fill factor.
+.SH ERRORS
+The
+.I btree
+access method routines may fail and set
+.I errno
+for any of the errors specified for the library routine
+.BR dbopen (3).
+.SH BUGS
+Only big and little endian byte order is supported.
+.SH SEE ALSO
+.BR dbopen (3),
+.BR hash (3),
+.BR mpool (3),
+.BR recno (3)
+.P
+.IR "The Ubiquitous B-tree" ,
+Douglas Comer, ACM Comput. Surv. 11, 2 (June 1979), 121-138.
+.P
+.IR "Prefix B-trees" ,
+Bayer and Unterauer, ACM Transactions on Database Systems, Vol. 2, 1
+(March 1977), 11-26.
+.P
+.IR "The Art of Computer Programming Vol. 3: Sorting and Searching" ,
+D.E. Knuth, 1968, pp 471-480.
diff --git a/man/man3/byteorder.3 b/man/man3/byteorder.3
new file mode 100644
index 000000000..76b699143
--- /dev/null
+++ b/man/man3/byteorder.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 21:29:05 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Thu Jul 26 14:06:20 2001 by Andries Brouwer (aeb@cwi.nl)
+.\"
+.TH BYTEORDER 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+htonl, htons, ntohl, ntohs \- convert values between host and network
+byte order
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <arpa/inet.h>
+.P
+.BI "uint32_t htonl(uint32_t " hostlong );
+.BI "uint16_t htons(uint16_t " hostshort );
+.P
+.BI "uint32_t ntohl(uint32_t " netlong );
+.BI "uint16_t ntohs(uint16_t " netshort );
+.fi
+.SH DESCRIPTION
+The
+.BR htonl ()
+function converts the unsigned integer
+.I hostlong
+from host byte order to network byte order.
+.P
+The
+.BR htons ()
+function converts the unsigned short integer
+.I hostshort
+from host byte order to network byte order.
+.P
+The
+.BR ntohl ()
+function converts the unsigned integer
+.I netlong
+from network byte order to host byte order.
+.P
+The
+.BR ntohs ()
+function converts the unsigned short integer
+.I netshort
+from network byte order to host byte order.
+.P
+On the i386 the host byte order is Least Significant Byte first,
+whereas the network byte order, as used on the Internet, is Most
+Significant Byte first.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR htonl (),
+.BR htons (),
+.BR ntohl (),
+.BR ntohs ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR bswap (3),
+.BR endian (3),
+.BR gethostbyname (3),
+.BR getservent (3)
diff --git a/man/man3/bzero.3 b/man/man3/bzero.3
new file mode 100644
index 000000000..f6c0ca2f3
--- /dev/null
+++ b/man/man3/bzero.3
@@ -0,0 +1,158 @@
+'\" t
+.\" Copyright (C) 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH bzero 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bzero, explicit_bzero \- zero a byte string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <strings.h>
+.P
+.BI "void bzero(void " s [. n "], size_t " n );
+.P
+.B #include <string.h>
+.P
+.BI "void explicit_bzero(void " s [. n "], size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR bzero ()
+function erases the data in the
+.I n
+bytes of the memory starting at the location pointed to by
+.IR s ,
+by writing zeros (bytes containing \[aq]\e0\[aq]) to that area.
+.P
+The
+.BR explicit_bzero ()
+function performs the same task as
+.BR bzero ().
+It differs from
+.BR bzero ()
+in that it guarantees that compiler optimizations will not remove the
+erase operation if the compiler deduces that the operation is "unnecessary".
+.SH RETURN VALUE
+None.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR bzero (),
+.BR explicit_bzero ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+.TP
+.BR explicit_bzero ()
+glibc 2.25.
+.IP
+The
+.BR explicit_bzero ()
+function is a nonstandard extension that is also present on some of the BSDs.
+Some other implementations have a similar function, such as
+.BR memset_explicit ()
+or
+.BR memset_s ().
+.TP
+.BR bzero ()
+4.3BSD.
+.IP
+Marked as LEGACY in POSIX.1-2001.
+Removed in POSIX.1-2008.
+.SH NOTES
+The
+.BR explicit_bzero ()
+function addresses a problem that security-conscious applications
+may run into when using
+.BR bzero ():
+if the compiler can deduce that the location to be zeroed will
+never again be touched by a
+.I correct
+program, then it may remove the
+.BR bzero ()
+call altogether.
+This is a problem if the intent of the
+.BR bzero ()
+call was to erase sensitive data (e.g., passwords)
+to prevent the possibility that the data was leaked
+by an incorrect or compromised program.
+Calls to
+.BR explicit_bzero ()
+are never optimized away by the compiler.
+.P
+The
+.BR explicit_bzero ()
+function does not solve all problems associated with erasing sensitive data:
+.IP \[bu] 3
+The
+.BR explicit_bzero ()
+function does
+.I not
+guarantee that sensitive data is completely erased from memory.
+(The same is true of
+.BR bzero ().)
+For example, there may be copies of the sensitive data in
+a register and in "scratch" stack areas.
+The
+.BR explicit_bzero ()
+function is not aware of these copies, and can't erase them.
+.IP \[bu]
+In some circumstances,
+.BR explicit_bzero ()
+can
+.I decrease
+security.
+If the compiler determined that the variable containing the
+sensitive data could be optimized to be stored in a register
+(because it is small enough to fit in a register,
+and no operation other than the
+.BR explicit_bzero ()
+call would need to take the address of the variable), then the
+.BR explicit_bzero ()
+call will force the data to be copied from the register
+to a location in RAM that is then immediately erased
+(while the copy in the register remains unaffected).
+The problem here is that data in RAM is more likely to be exposed
+by a bug than data in a register, and thus the
+.BR explicit_bzero ()
+call creates a brief time window where the sensitive data is more
+vulnerable than it would otherwise have been
+if no attempt had been made to erase the data.
+.P
+Note that declaring the sensitive variable with the
+.B volatile
+qualifier does
+.I not
+eliminate the above problems.
+Indeed, it will make them worse, since, for example,
+it may force a variable that would otherwise have been optimized
+into a register to instead be maintained in (more vulnerable)
+RAM for its entire lifetime.
+.P
+Notwithstanding the above details, for security-conscious applications, using
+.BR explicit_bzero ()
+is generally preferable to not using it.
+The developers of
+.BR explicit_bzero ()
+anticipate that future compilers will recognize calls to
+.BR explicit_bzero ()
+and take steps to ensure that all copies of the sensitive data are erased,
+including copies in registers or in "scratch" stack areas.
+.SH SEE ALSO
+.BR bstring (3),
+.BR memset (3),
+.BR swab (3)
diff --git a/man/man3/cabs.3 b/man/man3/cabs.3
new file mode 100644
index 000000000..97729e43c
--- /dev/null
+++ b/man/man3/cabs.3
@@ -0,0 +1,54 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cabs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cabs, cabsf, cabsl \- absolute value of a complex number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double cabs(double complex " z );
+.BI "float cabsf(float complex " z );
+.BI "long double cabsl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions return the absolute value of the complex number
+.IR z .
+The result is a real number.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cabs (),
+.BR cabsf (),
+.BR cabsl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH NOTES
+The function is actually an alias for
+.I "hypot(a,\ b)"
+(or, equivalently,
+.IR "sqrt(a*a\ +\ b*b)" ).
+.SH SEE ALSO
+.BR abs (3),
+.BR cimag (3),
+.BR hypot (3),
+.BR complex (7)
diff --git a/man/man3/cabsf.3 b/man/man3/cabsf.3
new file mode 100644
index 000000000..e50ac96b7
--- /dev/null
+++ b/man/man3/cabsf.3
@@ -0,0 +1 @@
+.so man3/cabs.3
diff --git a/man/man3/cabsl.3 b/man/man3/cabsl.3
new file mode 100644
index 000000000..e50ac96b7
--- /dev/null
+++ b/man/man3/cabsl.3
@@ -0,0 +1 @@
+.so man3/cabs.3
diff --git a/man/man3/cacos.3 b/man/man3/cacos.3
new file mode 100644
index 000000000..13a57e1ab
--- /dev/null
+++ b/man/man3/cacos.3
@@ -0,0 +1,93 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cacos 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cacos, cacosf, cacosl \- complex arc cosine
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex cacos(double complex " z );
+.BI "float complex cacosf(float complex " z );
+.BI "long double complex cacosl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex arc cosine of
+.IR z .
+If \fIy\ =\ cacos(z)\fP, then \fIz\ =\ ccos(y)\fP.
+The real part of
+.I y
+is chosen in the interval [0,pi].
+.P
+One has:
+.P
+.nf
+    cacos(z) = \-i * clog(z + i * csqrt(1 \- z * z))
+.fi
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cacos (),
+.BR cacosf (),
+.BR cacosl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH EXAMPLES
+.\" SRC BEGIN (cacos.c)
+.EX
+/* Link with "\-lm" */
+\&
+#include <complex.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    double complex z, c, f;
+    double complex i = I;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <real> <imag>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    z = atof(argv[1]) + atof(argv[2]) * I;
+\&
+    c = cacos(z);
+\&
+    printf("cacos() = %6.3f %6.3f*i\en", creal(c), cimag(c));
+\&
+    f = \-i * clog(z + i * csqrt(1 \- z * z));
+\&
+    printf("formula = %6.3f %6.3f*i\en", creal(f), cimag(f));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ccos (3),
+.BR clog (3),
+.BR complex (7)
diff --git a/man/man3/cacosf.3 b/man/man3/cacosf.3
new file mode 100644
index 000000000..a4f10e17f
--- /dev/null
+++ b/man/man3/cacosf.3
@@ -0,0 +1 @@
+.so man3/cacos.3
diff --git a/man/man3/cacosh.3 b/man/man3/cacosh.3
new file mode 100644
index 000000000..c6b3a2067
--- /dev/null
+++ b/man/man3/cacosh.3
@@ -0,0 +1,95 @@
+'\" t
+.\" Copyright 2002 Walter Harms(walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cacosh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cacosh, cacoshf, cacoshl \- complex arc hyperbolic cosine
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex cacosh(double complex " z );
+.BI "float complex cacoshf(float complex " z );
+.BI "long double complex cacoshl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex arc hyperbolic cosine of
+.IR z .
+If \fIy\ =\ cacosh(z)\fP, then \fIz\ =\ ccosh(y)\fP.
+The imaginary part of
+.I y
+is chosen in the interval [\-pi,pi].
+The real part of
+.I y
+is chosen nonnegative.
+.P
+One has:
+.P
+.nf
+    cacosh(z) = 2 * clog(csqrt((z + 1) / 2) + csqrt((z \- 1) / 2))
+.fi
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cacosh (),
+.BR cacoshf (),
+.BR cacoshl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+glibc 2.1.
+.SH EXAMPLES
+.\" SRC BEGIN (cacosh.c)
+.EX
+/* Link with "\-lm" */
+\&
+#include <complex.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    double complex z, c, f;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <real> <imag>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    z = atof(argv[1]) + atof(argv[2]) * I;
+\&
+    c = cacosh(z);
+    printf("cacosh() = %6.3f %6.3f*i\en", creal(c), cimag(c));
+\&
+    f = 2 * clog(csqrt((z + 1)/2) + csqrt((z \- 1)/2));
+    printf("formula  = %6.3f %6.3f*i\en", creal(f), cimag(f));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR acosh (3),
+.BR cabs (3),
+.BR ccosh (3),
+.BR cimag (3),
+.BR complex (7)
diff --git a/man/man3/cacoshf.3 b/man/man3/cacoshf.3
new file mode 100644
index 000000000..c89c010f2
--- /dev/null
+++ b/man/man3/cacoshf.3
@@ -0,0 +1 @@
+.so man3/cacosh.3
diff --git a/man/man3/cacoshl.3 b/man/man3/cacoshl.3
new file mode 100644
index 000000000..c89c010f2
--- /dev/null
+++ b/man/man3/cacoshl.3
@@ -0,0 +1 @@
+.so man3/cacosh.3
diff --git a/man/man3/cacosl.3 b/man/man3/cacosl.3
new file mode 100644
index 000000000..a4f10e17f
--- /dev/null
+++ b/man/man3/cacosl.3
@@ -0,0 +1 @@
+.so man3/cacos.3
diff --git a/man/man3/calloc.3 b/man/man3/calloc.3
new file mode 100644
index 000000000..a4b9d4455
--- /dev/null
+++ b/man/man3/calloc.3
@@ -0,0 +1 @@
+.so man3/malloc.3
diff --git a/man/man3/callrpc.3 b/man/man3/callrpc.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/callrpc.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/canonicalize_file_name.3 b/man/man3/canonicalize_file_name.3
new file mode 100644
index 000000000..d5fcd0f0a
--- /dev/null
+++ b/man/man3/canonicalize_file_name.3
@@ -0,0 +1,80 @@
+'\" t
+.\" Copyright 2013 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" (Replaces an earlier page by Walter Harms and Michael Kerrisk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH canonicalize_file_name 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+canonicalize_file_name \- return the canonicalized absolute pathname
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <stdlib.h>
+.P
+.BI "char *canonicalize_file_name(const char *" path ");"
+.fi
+.SH DESCRIPTION
+The
+.BR canonicalize_file_name ()
+function returns a null-terminated string containing
+the canonicalized absolute pathname corresponding to
+.IR path .
+In the returned string, symbolic links are resolved, as are
+.I .
+and
+.I ..
+pathname components.
+Consecutive slash
+.RI ( / )
+characters are replaced by a single slash.
+.P
+The returned string is dynamically allocated by
+.BR canonicalize_file_name ()
+and the caller should deallocate it with
+.BR free (3)
+when it is no longer required.
+.P
+The call
+.I canonicalize_file_name(path)
+is equivalent to the call:
+.P
+.in +4n
+.EX
+realpath(path, NULL);
+.EE
+.in
+.SH RETURN VALUE
+On success,
+.BR canonicalize_file_name ()
+returns a null-terminated string.
+On error (e.g., a pathname component is unreadable or does not exist),
+.BR canonicalize_file_name ()
+returns NULL and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+See
+.BR realpath (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR canonicalize_file_name ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR readlink (2),
+.BR realpath (3)
diff --git a/man/man3/carg.3 b/man/man3/carg.3
new file mode 100644
index 000000000..f95be60e4
--- /dev/null
+++ b/man/man3/carg.3
@@ -0,0 +1,88 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH carg 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+carg, cargf, cargl \- calculate the complex argument
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double carg(double complex " z ");"
+.BI "float cargf(float complex " z ");"
+.BI "long double cargl(long double complex " z ");"
+.fi
+.SH DESCRIPTION
+These functions calculate the complex argument (also called phase angle) of
+.IR z ,
+with a branch cut along the negative real axis.
+.P
+A complex number can be described by two real coordinates.
+One may use rectangular coordinates and gets
+.P
+.in +4n
+.EX
+z = x + I * y
+.EE
+.in
+.P
+where
+.I x\~=\~creal(z)
+and
+.IR y\~=\~cimag(z) .
+.P
+Or one may use polar coordinates and gets
+.P
+.in +4n
+.EX
+z = r * cexp(I * a)
+.EE
+.in
+.P
+where
+.I r\~=\~cabs(z)
+is the "radius", the "modulus", the absolute value of
+.IR z ,
+and
+.I a\~=\~carg(z)
+is the "phase angle", the argument of
+.IR z .
+.P
+One has:
+.P
+.in +4n
+.EX
+tan(carg(z)) = cimag(z) / creal(z)
+.EE
+.in
+.SH RETURN VALUE
+The return value is in the range of [\-pi,pi].
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR carg (),
+.BR cargf (),
+.BR cargl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR complex (7)
diff --git a/man/man3/cargf.3 b/man/man3/cargf.3
new file mode 100644
index 000000000..c181aa420
--- /dev/null
+++ b/man/man3/cargf.3
@@ -0,0 +1 @@
+.so man3/carg.3
diff --git a/man/man3/cargl.3 b/man/man3/cargl.3
new file mode 100644
index 000000000..c181aa420
--- /dev/null
+++ b/man/man3/cargl.3
@@ -0,0 +1 @@
+.so man3/carg.3
diff --git a/man/man3/casin.3 b/man/man3/casin.3
new file mode 100644
index 000000000..af3ea3890
--- /dev/null
+++ b/man/man3/casin.3
@@ -0,0 +1,57 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH casin 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+casin, casinf, casinl \- complex arc sine
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex casin(double complex " z );
+.BI "float complex casinf(float complex " z );
+.BI "long double complex casinl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex arc sine of
+.IR z .
+If \fIy\ =\ casin(z)\fP, then \fIz\ =\ csin(y)\fP.
+The real part of
+.I y
+is chosen in the interval [\-pi/2,pi/2].
+.P
+One has:
+.P
+.nf
+    casin(z) = \-i clog(iz + csqrt(1 \- z * z))
+.fi
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR casin (),
+.BR casinf (),
+.BR casinl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR clog (3),
+.BR csin (3),
+.BR complex (7)
diff --git a/man/man3/casinf.3 b/man/man3/casinf.3
new file mode 100644
index 000000000..582875fae
--- /dev/null
+++ b/man/man3/casinf.3
@@ -0,0 +1 @@
+.so man3/casin.3
diff --git a/man/man3/casinh.3 b/man/man3/casinh.3
new file mode 100644
index 000000000..198e56ab9
--- /dev/null
+++ b/man/man3/casinh.3
@@ -0,0 +1,61 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH casinh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+casinh, casinhf, casinhl \- complex arc sine hyperbolic
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex casinh(double complex " z );
+.BI "float complex casinhf(float complex " z );
+.BI "long double complex casinhl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex arc hyperbolic sine of
+.IR z .
+If \fIy\~=\~casinh(z)\fP, then \fIz\~=\~csinh(y)\fP.
+The imaginary part of
+.I y
+is chosen in the interval [\-pi/2,pi/2].
+.P
+One has:
+.P
+.in +4n
+.EX
+casinh(z) = clog(z + csqrt(z * z + 1))
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR casinh (),
+.BR casinhf (),
+.BR casinhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR asinh (3),
+.BR cabs (3),
+.BR cimag (3),
+.BR csinh (3),
+.BR complex (7)
diff --git a/man/man3/casinhf.3 b/man/man3/casinhf.3
new file mode 100644
index 000000000..c2eada89d
--- /dev/null
+++ b/man/man3/casinhf.3
@@ -0,0 +1 @@
+.so man3/casinh.3
diff --git a/man/man3/casinhl.3 b/man/man3/casinhl.3
new file mode 100644
index 000000000..c2eada89d
--- /dev/null
+++ b/man/man3/casinhl.3
@@ -0,0 +1 @@
+.so man3/casinh.3
diff --git a/man/man3/casinl.3 b/man/man3/casinl.3
new file mode 100644
index 000000000..582875fae
--- /dev/null
+++ b/man/man3/casinl.3
@@ -0,0 +1 @@
+.so man3/casin.3
diff --git a/man/man3/catan.3 b/man/man3/catan.3
new file mode 100644
index 000000000..d8e290853
--- /dev/null
+++ b/man/man3/catan.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH catan 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+catan, catanf, catanl \- complex arc tangents
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex catan(double complex " z );
+.BI "float complex catanf(float complex " z );
+.BI "long double complex catanl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex arc tangent of
+.IR z .
+If \fIy\~=\~catan(z)\fP, then \fIz\~=\~ctan(y)\fP.
+The real part of
+.I y
+is chosen in the interval [\-pi/2, pi/2].
+.P
+One has:
+.P
+.in +4n
+.EX
+catan(z) = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i)
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR catan (),
+.BR catanf (),
+.BR catanl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH EXAMPLES
+.\" SRC BEGIN (catan.c)
+.EX
+/* Link with "\-lm" */
+\&
+#include <complex.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    double complex z, c, f;
+    double complex i = I;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <real> <imag>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    z = atof(argv[1]) + atof(argv[2]) * I;
+\&
+    c = catan(z);
+    printf("catan() = %6.3f %6.3f*i\en", creal(c), cimag(c));
+\&
+    f = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i);
+    printf("formula = %6.3f %6.3f*i\en", creal(f), cimag(f));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ccos (3),
+.BR clog (3),
+.BR ctan (3),
+.BR complex (7)
diff --git a/man/man3/catanf.3 b/man/man3/catanf.3
new file mode 100644
index 000000000..d1e25223d
--- /dev/null
+++ b/man/man3/catanf.3
@@ -0,0 +1 @@
+.so man3/catan.3
diff --git a/man/man3/catanh.3 b/man/man3/catanh.3
new file mode 100644
index 000000000..f6749fe6c
--- /dev/null
+++ b/man/man3/catanh.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH catanh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+catanh, catanhf, catanhl \- complex arc tangents hyperbolic
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex catanh(double complex " z );
+.BI "float complex catanhf(float complex " z );
+.BI "long double complex catanhl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex arc hyperbolic tangent of
+.IR z .
+If \fIy\~=\~catanh(z)\fP, then \fIz\~=\~ctanh(y)\fP.
+The imaginary part of
+.I y
+is chosen in the interval [\-pi/2,pi/2].
+.P
+One has:
+.P
+.in +4n
+.EX
+catanh(z) = 0.5 * (clog(1 + z) \- clog(1 \- z))
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR catanh (),
+.BR catanhf (),
+.BR catanhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH EXAMPLES
+.\" SRC BEGIN (catanh.c)
+.EX
+/* Link with "\-lm" */
+\&
+#include <complex.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    double complex z, c, f;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <real> <imag>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    z = atof(argv[1]) + atof(argv[2]) * I;
+\&
+    c = catanh(z);
+    printf("catanh() = %6.3f %6.3f*i\en", creal(c), cimag(c));
+\&
+    f = 0.5 * (clog(1 + z) \- clog(1 \- z));
+    printf("formula  = %6.3f %6.3f*i\en", creal(f), cimag(f));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR atanh (3),
+.BR cabs (3),
+.BR cimag (3),
+.BR ctanh (3),
+.BR complex (7)
diff --git a/man/man3/catanhf.3 b/man/man3/catanhf.3
new file mode 100644
index 000000000..23f22a4a8
--- /dev/null
+++ b/man/man3/catanhf.3
@@ -0,0 +1 @@
+.so man3/catanh.3
diff --git a/man/man3/catanhl.3 b/man/man3/catanhl.3
new file mode 100644
index 000000000..23f22a4a8
--- /dev/null
+++ b/man/man3/catanhl.3
@@ -0,0 +1 @@
+.so man3/catanh.3
diff --git a/man/man3/catanl.3 b/man/man3/catanl.3
new file mode 100644
index 000000000..d1e25223d
--- /dev/null
+++ b/man/man3/catanl.3
@@ -0,0 +1 @@
+.so man3/catan.3
diff --git a/man/man3/catclose.3 b/man/man3/catclose.3
new file mode 100644
index 000000000..92ff6665a
--- /dev/null
+++ b/man/man3/catclose.3
@@ -0,0 +1 @@
+.so man3/catopen.3
diff --git a/man/man3/catgets.3 b/man/man3/catgets.3
new file mode 100644
index 000000000..58320b673
--- /dev/null
+++ b/man/man3/catgets.3
@@ -0,0 +1,88 @@
+'\" t
+.\" Copyright 1993 Mitchum DSouza <m.dsouza@mrc-applied-psychology.cambridge.ac.uk>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Updated, aeb, 980809
+.TH catgets 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+catgets \- get message from a message catalog
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <nl_types.h>
+.P
+.BI "char *catgets(nl_catd " catalog ", int " set_number \
+", int " message_number ,
+.BI "              const char *" message );
+.fi
+.SH DESCRIPTION
+.BR catgets ()
+reads the message
+.IR message_number ,
+in set
+.IR set_number ,
+from the message catalog identified by
+.IR catalog ,
+where
+.I catalog
+is a catalog descriptor returned from an earlier call to
+.BR catopen (3).
+The fourth argument,
+.IR message ,
+points to a default message string which will be returned by
+.BR catgets ()
+if the identified message catalog is not currently available.
+The
+message-text is contained in an internal buffer area and should be copied by
+the application if it is to be saved or modified.
+The return string is
+always terminated with a null byte (\[aq]\e0\[aq]).
+.SH RETURN VALUE
+On success,
+.BR catgets ()
+returns a pointer to an internal buffer area
+containing the null-terminated message string.
+On failure,
+.BR catgets ()
+returns the value
+.IR message .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR catgets ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+The
+.BR catgets ()
+function is available only in libc.so.4.4.4c and above.
+.P
+The Jan 1987 X/Open Portability Guide specifies a more subtle
+error return:
+.I message
+is returned if the message catalog specified by
+.I catalog
+is not available, while an empty string is returned
+when the message catalog is available but does not contain
+the specified message.
+These two possible error returns seem to be discarded in SUSv2
+in favor of always returning
+.IR message .
+.SH SEE ALSO
+.BR catopen (3),
+.BR setlocale (3)
diff --git a/man/man3/catopen.3 b/man/man3/catopen.3
new file mode 100644
index 000000000..4fc327add
--- /dev/null
+++ b/man/man3/catopen.3
@@ -0,0 +1,199 @@
+'\" t
+.\" Copyright 1993 Mitchum DSouza <m.dsouza@mrc-applied-psychology.cambridge.ac.uk>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Thu Dec 13 22:51:19 2001 by Martin Schulze <joey@infodrom.org>
+.\" Modified 2001-12-14 aeb
+.\"
+.TH catopen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+catopen, catclose \- open/close a message catalog
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <nl_types.h>
+.P
+.BI "nl_catd catopen(const char *" name ", int " flag );
+.BI "int catclose(nl_catd " catalog );
+.fi
+.SH DESCRIPTION
+The function
+.BR catopen ()
+opens a message catalog and returns a catalog descriptor.
+The descriptor remains valid until
+.BR catclose ()
+or
+.BR execve (2).
+If a file descriptor is used to implement catalog descriptors,
+then the
+.B FD_CLOEXEC
+flag will be set.
+.P
+The argument
+.I name
+specifies the name of the message catalog to be opened.
+If
+.I name
+specifies an absolute path (i.e., contains a \[aq]/\[aq]),
+then
+.I name
+specifies a pathname for the message catalog.
+Otherwise, the environment variable
+.B NLSPATH
+is used with
+.I name
+substituted for
+.B %N
+(see
+.BR locale (7)).
+It is unspecified whether
+.B NLSPATH
+will be used when the process has root privileges.
+If
+.B NLSPATH
+does not exist in the environment,
+or if a message catalog cannot be opened
+in any of the paths specified by it,
+then an implementation defined path is used.
+This latter default path may depend on the
+.B LC_MESSAGES
+locale setting when the
+.I flag
+argument is
+.B NL_CAT_LOCALE
+and on the
+.B LANG
+environment variable when the
+.I flag
+argument is 0.
+Changing the
+.B LC_MESSAGES
+part of the locale may invalidate
+open catalog descriptors.
+.P
+The
+.I flag
+argument to
+.BR catopen ()
+is used to indicate the source for the language to use.
+If it is set to
+.BR NL_CAT_LOCALE ,
+then it will use the current locale setting for
+.BR LC_MESSAGES .
+Otherwise, it will use the
+.B LANG
+environment variable.
+.P
+The function
+.BR catclose ()
+closes the message catalog identified by
+.IR catalog .
+It invalidates any subsequent references to the message catalog
+defined by
+.IR catalog .
+.SH RETURN VALUE
+The function
+.BR catopen ()
+returns a message catalog descriptor of type
+.I nl_catd
+on success.
+On failure, it returns
+.I (nl_catd)\~\-1
+and sets
+.I errno
+to indicate the error.
+The possible error values include all
+possible values for the
+.BR open (2)
+call.
+.P
+The function
+.BR catclose ()
+returns 0 on success, or \-1 on failure.
+.SH ENVIRONMENT
+.TP
+.B LC_MESSAGES
+May be the source of the
+.B LC_MESSAGES
+locale setting, and thus
+determine the language to use if
+.I flag
+is set to
+.BR NL_CAT_LOCALE .
+.TP
+.B LANG
+The language to use if
+.I flag
+is 0.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR catopen ()
+T}	Thread safety	MT-Safe env
+T{
+.na
+.nh
+.BR catclose ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The above is the POSIX.1 description.
+The glibc value for
+.B NL_CAT_LOCALE
+is 1.
+.\" (Compare
+.\" .B MCLoadAll
+.\" below.)
+The default path varies, but usually looks at a number of places below
+.IR /usr/share/locale .
+.\" .SS Linux notes
+.\" These functions are available for Linux since libc 4.4.4c.
+.\" In the case of linux libc4 and libc5, the catalog descriptor
+.\" .I nl_catd
+.\" is a
+.\" .BR mmap (2)'ed
+.\" area of memory and not a file descriptor.
+.\" The
+.\" .I flag
+.\" argument to
+.\" .BR catopen ()
+.\" should be either
+.\" .B MCLoadBySet
+.\" (=0) or
+.\" .B MCLoadAll
+.\" (=1).
+.\" The former value indicates that a set from the catalog is to be
+.\" loaded when needed, whereas the latter causes the initial call to
+.\" .BR catopen ()
+.\" to load the entire catalog into memory.
+.\" The default search path varies, but usually looks at a number of places below
+.\" .I /etc/locale
+.\" and
+.\" .IR /usr/lib/locale .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.\" In XPG 1987, Vol. 3 it says:
+.\" .I "The flag argument of catopen is reserved for future use"
+.\" .IR "and should be set to 0" .
+.\"
+.\" It is unclear what the source was for the constants
+.\" .B MCLoadBySet
+.\" and
+.\" .B MCLoadAll
+.\" (see below).
+.SH SEE ALSO
+.BR catgets (3),
+.BR setlocale (3)
diff --git a/man/man3/cbc_crypt.3 b/man/man3/cbc_crypt.3
new file mode 100644
index 000000000..853c9cbdf
--- /dev/null
+++ b/man/man3/cbc_crypt.3
@@ -0,0 +1 @@
+.so man3/des_crypt.3
diff --git a/man/man3/cbrt.3 b/man/man3/cbrt.3
new file mode 100644
index 000000000..64fc3c072
--- /dev/null
+++ b/man/man3/cbrt.3
@@ -0,0 +1,90 @@
+'\" t
+.\" Copyright 1995 Jim Van Zandt <jrv@vanzandt.mv.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" changed `square root' into `cube root' - aeb, 950919
+.\"
+.\" Modified 2002-07-27 Walter Harms
+.\" (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH cbrt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cbrt, cbrtf, cbrtl \- cube root function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double cbrt(double " x );
+.BI "float cbrtf(float " x );
+.BI "long double cbrtl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR cbrt ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR cbrtf (),
+.BR cbrtl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the (real) cube root of
+.IR x .
+This function cannot fail;
+every representable real value
+has a real cube root,
+and rounding it to a representable value
+never causes overflow nor underflow.
+.SH RETURN VALUE
+These functions return the cube root of
+.IR x .
+.P
+If
+.I x
+is +0, \-0, positive infinity, negative infinity, or NaN,
+.I x
+is returned.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cbrt (),
+.BR cbrtf (),
+.BR cbrtl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.\" .BR cbrt ()
+.\" was a GNU extension. It is now a C99 requirement.
+.SH SEE ALSO
+.BR pow (3),
+.BR sqrt (3)
diff --git a/man/man3/cbrtf.3 b/man/man3/cbrtf.3
new file mode 100644
index 000000000..b662c9ecd
--- /dev/null
+++ b/man/man3/cbrtf.3
@@ -0,0 +1 @@
+.so man3/cbrt.3
diff --git a/man/man3/cbrtl.3 b/man/man3/cbrtl.3
new file mode 100644
index 000000000..b662c9ecd
--- /dev/null
+++ b/man/man3/cbrtl.3
@@ -0,0 +1 @@
+.so man3/cbrt.3
diff --git a/man/man3/ccos.3 b/man/man3/ccos.3
new file mode 100644
index 000000000..0e77b3715
--- /dev/null
+++ b/man/man3/ccos.3
@@ -0,0 +1,57 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH ccos 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ccos, ccosf, ccosl \- complex cosine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex ccos(double complex " z );
+.BI "float complex ccosf(float complex " z );
+.BI "long double complex ccosl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex cosine of
+.IR z .
+.P
+The complex cosine function is defined as:
+.P
+.in +4n
+.EX
+ccos(z) = (exp(i * z) + exp(\-i * z)) / 2
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ccos (),
+.BR ccosf (),
+.BR ccosl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cacos (3),
+.BR csin (3),
+.BR ctan (3),
+.BR complex (7)
diff --git a/man/man3/ccosf.3 b/man/man3/ccosf.3
new file mode 100644
index 000000000..b4323ffa4
--- /dev/null
+++ b/man/man3/ccosf.3
@@ -0,0 +1 @@
+.so man3/ccos.3
diff --git a/man/man3/ccosh.3 b/man/man3/ccosh.3
new file mode 100644
index 000000000..053a83dd6
--- /dev/null
+++ b/man/man3/ccosh.3
@@ -0,0 +1,40 @@
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH ccosh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ccosh, ccoshf, ccoshl \- complex hyperbolic cosine
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex ccosh(double complex " z );
+.BI "float complex ccoshf(float complex " z );
+.BI "long double complex ccoshl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex hyperbolic cosine of
+.IR z .
+.P
+The complex hyperbolic cosine function is defined as:
+.P
+.in +4n
+.EX
+ccosh(z) = (exp(z)+exp(\-z))/2
+.EE
+.in
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cacosh (3),
+.BR csinh (3),
+.BR ctanh (3),
+.BR complex (7)
diff --git a/man/man3/ccoshf.3 b/man/man3/ccoshf.3
new file mode 100644
index 000000000..a777fbf7f
--- /dev/null
+++ b/man/man3/ccoshf.3
@@ -0,0 +1 @@
+.so man3/ccosh.3
diff --git a/man/man3/ccoshl.3 b/man/man3/ccoshl.3
new file mode 100644
index 000000000..a777fbf7f
--- /dev/null
+++ b/man/man3/ccoshl.3
@@ -0,0 +1 @@
+.so man3/ccosh.3
diff --git a/man/man3/ccosl.3 b/man/man3/ccosl.3
new file mode 100644
index 000000000..b4323ffa4
--- /dev/null
+++ b/man/man3/ccosl.3
@@ -0,0 +1 @@
+.so man3/ccos.3
diff --git a/man/man3/ceil.3 b/man/man3/ceil.3
new file mode 100644
index 000000000..197920616
--- /dev/null
+++ b/man/man3/ceil.3
@@ -0,0 +1,115 @@
+'\" t
+.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH ceil 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ceil, ceilf, ceill \- ceiling function: smallest integral value not
+less than argument
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double ceil(double " x );
+.BI "float ceilf(float " x );
+.BI "long double ceill(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ceilf (),
+.BR ceill ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the smallest integral value that is not less than
+.IR x .
+.P
+For example,
+.I ceil(0.5)
+is 1.0, and
+.I ceil(\-0.5)
+is 0.0.
+.SH RETURN VALUE
+These functions return the ceiling of
+.IR x .
+.P
+If
+.I x
+is integral, +0, \-0, NaN, or infinite,
+.I x
+itself is returned.
+.SH ERRORS
+No errors occur.
+POSIX.1-2001 documents a range error for overflows, but see NOTES.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ceil (),
+.BR ceilf (),
+.BR ceill ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH NOTES
+SUSv2 and POSIX.1-2001 contain text about overflow (which might set
+.I errno
+to
+.BR ERANGE ,
+or raise an
+.B FE_OVERFLOW
+exception).
+In practice, the result cannot overflow on any current machine,
+so this error-handling stuff is just nonsense.
+.\" The POSIX.1-2001 APPLICATION USAGE SECTION discusses this point.
+(More precisely, overflow can happen only when the maximum value
+of the exponent is smaller than the number of mantissa bits.
+For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
+the maximum value of the exponent is 127 (respectively, 1023),
+and the number of mantissa bits
+including the implicit bit
+is 24 (respectively, 53).)
+.P
+The integral value returned by these functions may be too large
+to store in an integer type
+.RI ( int ,
+.IR long ,
+etc.).
+To avoid an overflow, which will produce undefined results,
+an application should perform a range check on the returned value
+before assigning it to an integer type.
+.SH SEE ALSO
+.BR floor (3),
+.BR lrint (3),
+.BR nearbyint (3),
+.BR rint (3),
+.BR round (3),
+.BR trunc (3)
diff --git a/man/man3/ceilf.3 b/man/man3/ceilf.3
new file mode 100644
index 000000000..569d1baf7
--- /dev/null
+++ b/man/man3/ceilf.3
@@ -0,0 +1 @@
+.so man3/ceil.3
diff --git a/man/man3/ceill.3 b/man/man3/ceill.3
new file mode 100644
index 000000000..569d1baf7
--- /dev/null
+++ b/man/man3/ceill.3
@@ -0,0 +1 @@
+.so man3/ceil.3
diff --git a/man/man3/cexp.3 b/man/man3/cexp.3
new file mode 100644
index 000000000..917d04d8b
--- /dev/null
+++ b/man/man3/cexp.3
@@ -0,0 +1,58 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cexp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cexp, cexpf, cexpl \- complex exponential function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex cexp(double complex " z );
+.BI "float complex cexpf(float complex " z );
+.BI "long double complex cexpl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate e (2.71828..., the base of natural logarithms)
+raised to the power of
+.IR z .
+.P
+One has:
+.P
+.in +4n
+.EX
+cexp(I * z) = ccos(z) + I * csin(z)
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cexp (),
+.BR cexpf (),
+.BR cexpl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cexp2 (3),
+.BR clog (3),
+.BR cpow (3),
+.BR complex (7)
diff --git a/man/man3/cexp2.3 b/man/man3/cexp2.3
new file mode 100644
index 000000000..7a4f8c745
--- /dev/null
+++ b/man/man3/cexp2.3
@@ -0,0 +1,31 @@
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cexp2 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cexp2, cexp2f, cexp2l \- base-2 exponent of a complex number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex cexp2(double complex " z );
+.BI "float complex cexp2f(float complex " z );
+.BI "long double complex cexp2l(long double complex " z );
+.fi
+.SH DESCRIPTION
+The function returns 2 raised to the power of
+.IR z .
+.SH STANDARDS
+These function names are reserved for future use in C99.
+.P
+As at glibc 2.31, these functions are not provided in glibc.
+.\" But reserved in NAMESPACE.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cexp (3),
+.BR clog10 (3),
+.BR complex (7)
diff --git a/man/man3/cexp2f.3 b/man/man3/cexp2f.3
new file mode 100644
index 000000000..759ad34ce
--- /dev/null
+++ b/man/man3/cexp2f.3
@@ -0,0 +1 @@
+.so man3/cexp2.3
diff --git a/man/man3/cexp2l.3 b/man/man3/cexp2l.3
new file mode 100644
index 000000000..759ad34ce
--- /dev/null
+++ b/man/man3/cexp2l.3
@@ -0,0 +1 @@
+.so man3/cexp2.3
diff --git a/man/man3/cexpf.3 b/man/man3/cexpf.3
new file mode 100644
index 000000000..794d70711
--- /dev/null
+++ b/man/man3/cexpf.3
@@ -0,0 +1 @@
+.so man3/cexp.3
diff --git a/man/man3/cexpl.3 b/man/man3/cexpl.3
new file mode 100644
index 000000000..794d70711
--- /dev/null
+++ b/man/man3/cexpl.3
@@ -0,0 +1 @@
+.so man3/cexp.3
diff --git a/man/man3/cfgetispeed.3 b/man/man3/cfgetispeed.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/cfgetispeed.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/cfgetospeed.3 b/man/man3/cfgetospeed.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/cfgetospeed.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/cfmakeraw.3 b/man/man3/cfmakeraw.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/cfmakeraw.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/cfree.3 b/man/man3/cfree.3
new file mode 100644
index 000000000..80812804d
--- /dev/null
+++ b/man/man3/cfree.3
@@ -0,0 +1,132 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH cfree 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cfree \- free allocated memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.P
+.B "#include <stdlib.h>"
+.P
+/* In SunOS 4 */
+.BI "int cfree(void *" ptr );
+.P
+/* In glibc or FreeBSD libcompat */
+.BI "void cfree(void *" ptr );
+.P
+/* In SCO OpenServer */
+.BI "void cfree(char " ptr [. size " * ." num "], unsigned int " num ", \
+unsigned int " size );
+.P
+/* In Solaris watchmalloc.so.1 */
+.BI "void cfree(void " ptr [. elsize " * ." nelem "], size_t " nelem ", \
+size_t " elsize );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR cfree ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+This function should never be used.
+Use
+.BR free (3)
+instead.
+Starting with glibc 2.26, it has been removed from glibc.
+.SS 1-arg cfree
+In glibc, the function
+.BR cfree ()
+is a synonym for
+.BR free (3),
+"added for compatibility with SunOS".
+.P
+Other systems have other functions with this name.
+The declaration is sometimes in
+.I <stdlib.h>
+and sometimes in
+.IR <malloc.h> .
+.SS 3-arg cfree
+Some SCO and Solaris versions have malloc libraries with a 3-argument
+.BR cfree (),
+apparently as an analog to
+.BR calloc (3).
+.P
+If you need it while porting something, add
+.P
+.in +4n
+.EX
+#define cfree(p, n, s) free((p))
+.EE
+.in
+.P
+to your file.
+.P
+A frequently asked question is "Can I use
+.BR free (3)
+to free memory allocated with
+.BR calloc (3),
+or do I need
+.BR cfree ()?"
+Answer: use
+.BR free (3).
+.P
+An SCO manual writes: "The cfree routine is provided for compliance
+to the iBCSe2 standard and simply calls free.
+The num and size
+arguments to cfree are not used."
+.SH RETURN VALUE
+The SunOS version of
+.BR cfree ()
+(which is a synonym for
+.BR free (3))
+returns 1 on success and 0 on failure.
+In case of error,
+.I errno
+is set to
+.BR EINVAL :
+the value of
+.I ptr
+was not a pointer to a block previously allocated by
+one of the routines in the
+.BR malloc (3)
+family.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cfree ()
+T}	Thread safety	MT-Safe /* In glibc */
+.TE
+.SH VERSIONS
+The 3-argument version of
+.BR cfree ()
+as used by SCO conforms to the iBCSe2 standard:
+Intel386 Binary Compatibility Specification, Edition 2.
+.SH STANDARDS
+None.
+.SH HISTORY
+.\" commit 025b33ae84bb8f15b2748a1d8605dca453fce112
+Removed in glibc 2.26.
+.SH SEE ALSO
+.BR malloc (3)
diff --git a/man/man3/cfsetispeed.3 b/man/man3/cfsetispeed.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/cfsetispeed.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/cfsetospeed.3 b/man/man3/cfsetospeed.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/cfsetospeed.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/cfsetspeed.3 b/man/man3/cfsetspeed.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/cfsetspeed.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/cimag.3 b/man/man3/cimag.3
new file mode 100644
index 000000000..e4c8f08c2
--- /dev/null
+++ b/man/man3/cimag.3
@@ -0,0 +1,58 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cimag 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cimag, cimagf, cimagl \- get imaginary part of a complex number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double cimag(double complex " z );
+.BI "float cimagf(float complex " z );
+.BI "long double cimagl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions return the imaginary part of the complex number
+.IR z .
+.P
+One has:
+.P
+.in +4n
+.EX
+z = creal(z) + I * cimag(z)
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cimag (),
+.BR cimagf (),
+.BR cimagl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+GCC also supports __imag__.
+That is a GNU extension.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR creal (3),
+.BR complex (7)
diff --git a/man/man3/cimagf.3 b/man/man3/cimagf.3
new file mode 100644
index 000000000..e806455ae
--- /dev/null
+++ b/man/man3/cimagf.3
@@ -0,0 +1 @@
+.so man3/cimag.3
diff --git a/man/man3/cimagl.3 b/man/man3/cimagl.3
new file mode 100644
index 000000000..e806455ae
--- /dev/null
+++ b/man/man3/cimagl.3
@@ -0,0 +1 @@
+.so man3/cimag.3
diff --git a/man/man3/circleq.3 b/man/man3/circleq.3
new file mode 100644
index 000000000..75442e710
--- /dev/null
+++ b/man/man3/circleq.3
@@ -0,0 +1,318 @@
+.\" Copyright (c) 1993
+.\"    The Regents of the University of California.  All rights reserved.
+.\" and Copyright (c) 2020 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"
+.TH CIRCLEQ 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+CIRCLEQ_EMPTY,
+CIRCLEQ_ENTRY,
+CIRCLEQ_FIRST,
+CIRCLEQ_FOREACH,
+CIRCLEQ_FOREACH_REVERSE,
+CIRCLEQ_HEAD,
+CIRCLEQ_HEAD_INITIALIZER,
+CIRCLEQ_INIT,
+CIRCLEQ_INSERT_AFTER,
+CIRCLEQ_INSERT_BEFORE,
+CIRCLEQ_INSERT_HEAD,
+CIRCLEQ_INSERT_TAIL,
+CIRCLEQ_LAST,
+CIRCLEQ_LOOP_NEXT,
+CIRCLEQ_LOOP_PREV,
+CIRCLEQ_NEXT,
+CIRCLEQ_PREV,
+CIRCLEQ_REMOVE
+\- implementation of a doubly linked circular queue
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/queue.h>
+.P
+.B CIRCLEQ_ENTRY(TYPE);
+.P
+.B CIRCLEQ_HEAD(HEADNAME, TYPE);
+.BI "CIRCLEQ_HEAD CIRCLEQ_HEAD_INITIALIZER(CIRCLEQ_HEAD " head );
+.BI "void CIRCLEQ_INIT(CIRCLEQ_HEAD *" head );
+.P
+.BI "int CIRCLEQ_EMPTY(CIRCLEQ_HEAD *" head );
+.P
+.BI "void CIRCLEQ_INSERT_HEAD(CIRCLEQ_HEAD *" head ,
+.BI "                           struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.BI "void CIRCLEQ_INSERT_TAIL(CIRCLEQ_HEAD *" head ,
+.BI "                           struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.BI "void CIRCLEQ_INSERT_BEFORE(CIRCLEQ_HEAD *" head ", struct TYPE *" listelm ,
+.BI "                           struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.BI "void CIRCLEQ_INSERT_AFTER(CIRCLEQ_HEAD *" head ", struct TYPE *" listelm ,
+.BI "                           struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.P
+.BI "struct TYPE *CIRCLEQ_FIRST(CIRCLEQ_HEAD *" head );
+.BI "struct TYPE *CIRCLEQ_LAST(CIRCLEQ_HEAD *" head );
+.BI "struct TYPE *CIRCLEQ_PREV(struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.BI "struct TYPE *CIRCLEQ_NEXT(struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.BI "struct TYPE *CIRCLEQ_LOOP_PREV(CIRCLEQ_HEAD *" head ,
+.BI "                           struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.BI "struct TYPE *CIRCLEQ_LOOP_NEXT(CIRCLEQ_HEAD *" head ,
+.BI "                           struct TYPE *" elm ", CIRCLEQ_ENTRY " NAME );
+.P
+.BI "CIRCLEQ_FOREACH(struct TYPE *" var ", CIRCLEQ_HEAD *" head ,
+.BI "                           CIRCLEQ_ENTRY " NAME );
+.BI "CIRCLEQ_FOREACH_REVERSE(struct TYPE *" var ", CIRCLEQ_HEAD *" head ,
+.BI "                           CIRCLEQ_ENTRY " NAME );
+.P
+.BI "void CIRCLEQ_REMOVE(CIRCLEQ_HEAD *" head ", struct TYPE *" elm ,
+.BI "                           CIRCLEQ_ENTRY " NAME );
+.fi
+.SH DESCRIPTION
+These macros define and operate on doubly linked circular queues.
+.P
+In the macro definitions,
+.I TYPE
+is the name of a user-defined structure,
+that must contain a field of type
+.IR CIRCLEQ_ENTRY ,
+named
+.IR NAME .
+The argument
+.I HEADNAME
+is the name of a user-defined structure
+that must be declared using the macro
+.BR CIRCLEQ_HEAD ().
+.SS Creation
+A circular queue is headed by a structure defined by the
+.BR CIRCLEQ_HEAD ()
+macro.
+This structure contains a pair of pointers,
+one to the first element in the queue
+and the other to the last element in the queue.
+The elements are doubly linked
+so that an arbitrary element can be removed without traversing the queue.
+New elements can be added to the queue
+after an existing element,
+before an existing element,
+at the head of the queue,
+or at the end of the queue.
+A
+.I CIRCLEQ_HEAD
+structure is declared as follows:
+.P
+.in +4
+.EX
+CIRCLEQ_HEAD(HEADNAME, TYPE) head;
+.EE
+.in
+.P
+where
+.I struct HEADNAME
+is the structure to be defined, and
+.I struct TYPE
+is the type of the elements to be linked into the queue.
+A pointer to the head of the queue can later be declared as:
+.P
+.in +4
+.EX
+struct HEADNAME *headp;
+.EE
+.in
+.P
+(The names
+.I head
+and
+.I headp
+are user selectable.)
+.P
+.BR CIRCLEQ_ENTRY ()
+declares a structure that connects the elements in the queue.
+.P
+.BR CIRCLEQ_HEAD_INITIALIZER ()
+evaluates to an initializer for the queue
+.IR head .
+.P
+.BR CIRCLEQ_INIT ()
+initializes the queue referenced by
+.IR head .
+.P
+.BR CIRCLEQ_EMPTY ()
+evaluates to true if there are no items on the queue.
+.SS Insertion
+.BR CIRCLEQ_INSERT_HEAD ()
+inserts the new element
+.I elm
+at the head of the queue.
+.P
+.BR CIRCLEQ_INSERT_TAIL ()
+inserts the new element
+.I elm
+at the end of the queue.
+.P
+.BR CIRCLEQ_INSERT_BEFORE ()
+inserts the new element
+.I elm
+before the element
+.IR listelm .
+.P
+.BR CIRCLEQ_INSERT_AFTER ()
+inserts the new element
+.I elm
+after the element
+.IR listelm .
+.SS Traversal
+.BR CIRCLEQ_FIRST ()
+returns the first item on the queue.
+.P
+.BR CIRCLEQ_LAST ()
+returns the last item on the queue.
+.P
+.BR CIRCLEQ_PREV ()
+returns the previous item on the queue, or
+.I &head
+if this item is the first one.
+.P
+.BR CIRCLEQ_NEXT ()
+returns the next item on the queue, or
+.I &head
+if this item is the last one.
+.P
+.BR CIRCLEQ_LOOP_PREV ()
+returns the previous item on the queue.
+If
+.I elm
+is the first element on the queue, the last element is returned.
+.P
+.BR CIRCLEQ_LOOP_NEXT ()
+returns the next item on the queue.
+If
+.I elm
+is the last element on the queue, the first element is returned.
+.P
+.BR CIRCLEQ_FOREACH ()
+traverses the queue referenced by
+.I head
+in the forward direction, assigning each element in turn to
+.IR var .
+.I var
+is set to
+.I &head
+if the loop completes normally, or if there were no elements.
+.P
+.BR CIRCLEQ_FOREACH_REVERSE ()
+traverses the queue referenced by
+.I head
+in the reverse direction,
+assigning each element in turn to
+.IR var .
+.SS Removal
+.BR CIRCLEQ_REMOVE ()
+removes the element
+.I elm
+from the queue.
+.SH RETURN VALUE
+.BR CIRCLEQ_EMPTY ()
+returns nonzero if the queue is empty,
+and zero if the queue contains at least one entry.
+.P
+.BR CIRCLEQ_FIRST (),
+.BR CIRCLEQ_LAST (),
+.BR CIRCLEQ_LOOP_PREV (),
+and
+.BR CIRCLEQ_LOOP_NEXT ()
+return a pointer to the first, last, previous, or next
+.I TYPE
+structure, respectively.
+.P
+.BR CIRCLEQ_PREV (),
+and
+.BR CIRCLEQ_NEXT ()
+are similar to their
+.BR CIRCLEQ_LOOP_* ()
+counterparts,
+except that if the argument is the first or last element, respectively,
+they return
+.IR &head .
+.P
+.BR CIRCLEQ_HEAD_INITIALIZER ()
+returns an initializer that can be assigned to the queue
+.IR head .
+.SH STANDARDS
+BSD.
+.SH BUGS
+.BR CIRCLEQ_FOREACH ()
+and
+.BR CIRCLEQ_FOREACH_REVERSE ()
+don't allow
+.I var
+to be removed or freed within the loop,
+as it would interfere with the traversal.
+.BR CIRCLEQ_FOREACH_SAFE ()
+and
+.BR CIRCLEQ_FOREACH_REVERSE_SAFE (),
+which are present on the BSDs but are not present in glibc,
+fix this limitation by allowing
+.I var
+to safely be removed from the list and freed from within the loop
+without interfering with the traversal.
+.SH EXAMPLES
+.\" SRC BEGIN (circleq.c)
+.EX
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/queue.h>
+\&
+struct entry {
+    int data;
+    CIRCLEQ_ENTRY(entry) entries;           /* Queue */
+};
+\&
+CIRCLEQ_HEAD(circlehead, entry);
+\&
+int
+main(void)
+{
+    struct entry *n1, *n2, *n3, *np;
+    struct circlehead head;                 /* Queue head */
+    int i;
+\&
+    CIRCLEQ_INIT(&head);                    /* Initialize the queue */
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the head */
+    CIRCLEQ_INSERT_HEAD(&head, n1, entries);
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the tail */
+    CIRCLEQ_INSERT_TAIL(&head, n1, entries);
+\&
+    n2 = malloc(sizeof(struct entry));      /* Insert after */
+    CIRCLEQ_INSERT_AFTER(&head, n1, n2, entries);
+\&
+    n3 = malloc(sizeof(struct entry));      /* Insert before */
+    CIRCLEQ_INSERT_BEFORE(&head, n2, n3, entries);
+\&
+    CIRCLEQ_REMOVE(&head, n2, entries);     /* Deletion */
+    free(n2);
+                                            /* Forward traversal */
+    i = 0;
+    CIRCLEQ_FOREACH(np, &head, entries)
+        np\->data = i++;
+                                            /* Reverse traversal */
+    CIRCLEQ_FOREACH_REVERSE(np, &head, entries)
+        printf("%i\en", np\->data);
+                                            /* Queue deletion */
+    n1 = CIRCLEQ_FIRST(&head);
+    while (n1 != (void *)&head) {
+        n2 = CIRCLEQ_NEXT(n1, entries);
+        free(n1);
+        n1 = n2;
+    }
+    CIRCLEQ_INIT(&head);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR insque (3),
+.BR queue (7)
diff --git a/man/man3/clearenv.3 b/man/man3/clearenv.3
new file mode 100644
index 000000000..49bd8c2f5
--- /dev/null
+++ b/man/man3/clearenv.3
@@ -0,0 +1,137 @@
+'\" t
+.\" Copyright 2001 John Levon <moz@compsoc.man.ac.uk>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Additions, aeb, 2001-10-17.
+.TH clearenv 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clearenv \- clear the environment
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.B "int clearenv(void);"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR clearenv ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR clearenv ()
+function clears the environment of all name-value
+pairs and sets the value of the external variable
+.I environ
+to NULL.
+After this call, new variables can be added to the environment using
+.BR putenv (3)
+and
+.BR setenv (3).
+.SH RETURN VALUE
+The
+.BR clearenv ()
+function returns zero on success, and a nonzero
+value on failure.
+.\" Most versions of UNIX return -1 on error, or do not even have errors.
+.\" glibc info and the Watcom C library document "a nonzero value".
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR clearenv ()
+T}	Thread safety	MT-Unsafe const:env
+.TE
+.SH STANDARDS
+.TP
+.BR putenv ()
+POSIX.1-2008.
+.TP
+.BR clearenv ()
+None.
+.SH HISTORY
+.TP
+.BR putenv ()
+glibc 2.0.
+POSIX.1-2001.
+.TP
+.BR clearenv ()
+glibc 2.0.
+.P
+Various UNIX variants (DG/UX, HP-UX, QNX, ...).
+POSIX.9 (bindings for FORTRAN77).
+POSIX.1-1996 did not accept
+.BR clearenv ()
+and
+.BR putenv (3),
+but changed its mind and scheduled these functions for some
+later issue of this standard (see \[sc]B.4.6.1).
+However, POSIX.1-2001
+adds only
+.BR putenv (3),
+and rejected
+.BR clearenv ().
+.SH NOTES
+On systems where
+.BR clearenv ()
+is unavailable, the assignment
+.P
+.in +4n
+.EX
+environ = NULL;
+.EE
+.in
+.P
+will probably do.
+.P
+The
+.BR clearenv ()
+function may be useful in security-conscious applications that want to
+precisely control the environment that is passed to programs
+executed using
+.BR exec (3).
+The application would do this by first clearing the environment
+and then adding select environment variables.
+.P
+Note that the main effect of
+.BR clearenv ()
+is to adjust the value of the pointer
+.BR environ (7);
+this function does not erase the contents of the buffers
+containing the environment definitions.
+.P
+The DG/UX and Tru64 man pages write: If
+.I environ
+has been modified by anything other than the
+.BR putenv (3),
+.BR getenv (3),
+or
+.BR clearenv ()
+functions, then
+.BR clearenv ()
+will return an error and the process environment will remain unchanged.
+.\" .P
+.\" HP-UX has a ENOMEM error return.
+.SH SEE ALSO
+.BR getenv (3),
+.BR putenv (3),
+.BR setenv (3),
+.BR unsetenv (3),
+.BR environ (7)
diff --git a/man/man3/clearerr.3 b/man/man3/clearerr.3
new file mode 100644
index 000000000..3a95cca9f
--- /dev/null
+++ b/man/man3/clearerr.3
@@ -0,0 +1 @@
+.so man3/ferror.3
diff --git a/man/man3/clearerr_unlocked.3 b/man/man3/clearerr_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/clearerr_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/clnt_broadcast.3 b/man/man3/clnt_broadcast.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_broadcast.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_call.3 b/man/man3/clnt_call.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_call.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_control.3 b/man/man3/clnt_control.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_control.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_create.3 b/man/man3/clnt_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_destroy.3 b/man/man3/clnt_destroy.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_destroy.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_freeres.3 b/man/man3/clnt_freeres.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_freeres.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_geterr.3 b/man/man3/clnt_geterr.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_geterr.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_pcreateerror.3 b/man/man3/clnt_pcreateerror.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_pcreateerror.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_perrno.3 b/man/man3/clnt_perrno.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_perrno.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_perror.3 b/man/man3/clnt_perror.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_perror.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_spcreateerror.3 b/man/man3/clnt_spcreateerror.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_spcreateerror.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_sperrno.3 b/man/man3/clnt_sperrno.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_sperrno.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnt_sperror.3 b/man/man3/clnt_sperror.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnt_sperror.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clntraw_create.3 b/man/man3/clntraw_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clntraw_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clnttcp_create.3 b/man/man3/clnttcp_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clnttcp_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clntudp_bufcreate.3 b/man/man3/clntudp_bufcreate.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clntudp_bufcreate.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clntudp_create.3 b/man/man3/clntudp_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/clntudp_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/clock.3 b/man/man3/clock.3
new file mode 100644
index 000000000..292a0c137
--- /dev/null
+++ b/man/man3/clock.3
@@ -0,0 +1,101 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 21:27:01 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 14 Jun 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 	Added notes on differences from other UNIX systems with respect to
+.\"	waited-for children.
+.TH clock 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clock \- determine processor time
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.B clock_t clock(void);
+.fi
+.SH DESCRIPTION
+The
+.BR clock ()
+function returns an approximation of processor time used by the program.
+.SH RETURN VALUE
+The value returned is the CPU time used so far as a
+.IR clock_t ;
+to get the number of seconds used, divide by
+.BR CLOCKS_PER_SEC .
+If the processor time used is not available or its value cannot
+be represented, the function returns the value
+.IR (clock_t)\ \-1 .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR clock ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+XSI requires that
+.B CLOCKS_PER_SEC
+equals 1000000 independent
+of the actual resolution.
+.P
+On several other implementations,
+the value returned by
+.BR clock ()
+also includes the times of any children whose status has been
+collected via
+.BR wait (2)
+(or another wait-type call).
+Linux does not include the times of waited-for children in the
+value returned by
+.BR clock ().
+.\" I have seen this behavior on Irix 6.3, and the OSF/1, HP/UX, and
+.\" Solaris manual pages say that clock() also does this on those systems.
+.\" POSIX.1-2001 doesn't explicitly allow this, nor is there an
+.\" explicit prohibition. -- MTK
+The
+.BR times (2)
+function, which explicitly returns (separate) information about the
+caller and its children, may be preferable.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89.
+.P
+In glibc 2.17 and earlier,
+.BR clock ()
+was implemented on top of
+.BR times (2).
+For improved accuracy,
+since glibc 2.18, it is implemented on top of
+.BR clock_gettime (2)
+(using the
+.B CLOCK_PROCESS_CPUTIME_ID
+clock).
+.SH NOTES
+The C standard allows for arbitrary values at the start of the program;
+subtract the value returned from a call to
+.BR clock ()
+at the start of the program to get maximum portability.
+.P
+Note that the time can wrap around.
+On a 32-bit system where
+.B CLOCKS_PER_SEC
+equals 1000000 this function will return the same
+value approximately every 72 minutes.
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR getrusage (2),
+.BR times (2)
diff --git a/man/man3/clock_getcpuclockid.3 b/man/man3/clock_getcpuclockid.3
new file mode 100644
index 000000000..0d6e231d7
--- /dev/null
+++ b/man/man3/clock_getcpuclockid.3
@@ -0,0 +1,155 @@
+'\" t
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\" <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH clock_getcpuclockid 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clock_getcpuclockid \- obtain ID of a process CPU-time clock
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc ),
+since glibc 2.17
+.P
+Before glibc 2.17,
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.B #include <time.h>
+.nf
+.P
+.BI "int clock_getcpuclockid(pid_t " pid ", clockid_t *" clockid );
+.fi
+.P
+.ad l
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR clock_getcpuclockid ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR clock_getcpuclockid ()
+function obtains the ID of the CPU-time clock of the process whose ID is
+.IR pid ,
+and returns it in the location pointed to by
+.IR clockid .
+If
+.I pid
+is zero, then the clock ID of the CPU-time clock
+of the calling process is returned.
+.SH RETURN VALUE
+On success,
+.BR clock_getcpuclockid ()
+returns 0;
+on error, it returns one of the positive error numbers listed in ERRORS.
+.SH ERRORS
+.TP
+.B ENOSYS
+The kernel does not support obtaining the per-process
+CPU-time clock of another process, and
+.I pid
+does not specify the calling process.
+.TP
+.B EPERM
+The caller does not have permission to access
+the CPU-time clock of the process specified by
+.IR pid .
+(Specified in POSIX.1-2001;
+does not occur on Linux unless the kernel does not support
+obtaining the per-process CPU-time clock of another process.)
+.TP
+.B ESRCH
+There is no process with the ID
+.IR pid .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR clock_getcpuclockid ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.SH NOTES
+Calling
+.BR clock_gettime (2)
+with the clock ID obtained by a call to
+.BR clock_getcpuclockid ()
+with a
+.I pid
+of 0,
+is the same as using the clock ID
+.BR CLOCK_PROCESS_CPUTIME_ID .
+.SH EXAMPLES
+The example program below obtains the
+CPU-time clock ID of the process whose ID is given on the command line,
+and then uses
+.BR clock_gettime (2)
+to obtain the time on that clock.
+An example run is the following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 1" "                 # Show CPU clock of init process"
+CPU\-time clock for PID 1 is 2.213466748 seconds
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (clock_getcpuclockid.c)
+.EX
+#define _XOPEN_SOURCE 600
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    clockid_t clockid;
+    struct timespec ts;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "%s <process\-ID>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (clock_getcpuclockid(atoi(argv[1]), &clockid) != 0) {
+        perror("clock_getcpuclockid");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (clock_gettime(clockid, &ts) == \-1) {
+        perror("clock_gettime");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("CPU\-time clock for PID %s is %jd.%09ld seconds\en",
+           argv[1], (intmax_t) ts.tv_sec, ts.tv_nsec);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clock_getres (2),
+.BR timer_create (2),
+.BR pthread_getcpuclockid (3),
+.BR time (7)
diff --git a/man/man3/clog.3 b/man/man3/clog.3
new file mode 100644
index 000000000..ff2e8fb01
--- /dev/null
+++ b/man/man3/clog.3
@@ -0,0 +1,71 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH clog 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clog, clogf, clogl \- natural logarithm of a complex number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex clog(double complex " z );
+.BI "float complex clogf(float complex " z );
+.BI "long double complex clogl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex natural logarithm of
+.IR z ,
+with a branch cut along the negative real axis.
+.P
+The logarithm
+.BR clog ()
+is the inverse function of the exponential
+.BR cexp (3).
+Thus, if \fIy\ =\ clog(z)\fP, then \fIz\ =\ cexp(y)\fP.
+The imaginary part of
+.I y
+is chosen in the interval [\-pi,pi].
+.P
+One has:
+.P
+.in +4n
+.EX
+clog(z) = log(cabs(z)) + I * carg(z)
+.EE
+.in
+.P
+Note that
+.I z
+close to zero will cause an overflow.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR clog (),
+.BR clogf (),
+.BR clogl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cexp (3),
+.BR clog10 (3),
+.BR clog2 (3),
+.BR complex (7)
diff --git a/man/man3/clog10.3 b/man/man3/clog10.3
new file mode 100644
index 000000000..1c798cf07
--- /dev/null
+++ b/man/man3/clog10.3
@@ -0,0 +1,75 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH clog10 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clog10, clog10f, clog10l \- base-10 logarithm of a complex number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <complex.h>
+.P
+.BI "double complex clog10(double complex " z );
+.BI "float complex clog10f(float complex " z );
+.BI "long double complex clog10l(long double complex " z );
+.fi
+.SH DESCRIPTION
+The call
+.I clog10(z)
+is equivalent to:
+.P
+.in +4n
+.EX
+clog(z)/log(10)
+.EE
+.in
+.P
+or equally:
+.P
+.in +4n
+.EX
+log10(cabs(c)) + I * carg(c) / log(10)
+.EE
+.in
+.P
+The other functions perform the same task for
+.I float
+and
+.IR "long double" .
+.P
+Note that
+.I z
+close to zero will cause an overflow.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR clog10 (),
+.BR clog10f (),
+.BR clog10l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.P
+The identifiers are reserved for future use in C99 and C11.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cexp (3),
+.BR clog (3),
+.BR clog2 (3),
+.BR complex (7)
diff --git a/man/man3/clog10f.3 b/man/man3/clog10f.3
new file mode 100644
index 000000000..5840d54d0
--- /dev/null
+++ b/man/man3/clog10f.3
@@ -0,0 +1 @@
+.so man3/clog10.3
diff --git a/man/man3/clog10l.3 b/man/man3/clog10l.3
new file mode 100644
index 000000000..5840d54d0
--- /dev/null
+++ b/man/man3/clog10l.3
@@ -0,0 +1 @@
+.so man3/clog10.3
diff --git a/man/man3/clog2.3 b/man/man3/clog2.3
new file mode 100644
index 000000000..b406a4229
--- /dev/null
+++ b/man/man3/clog2.3
@@ -0,0 +1,45 @@
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH clog2 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clog2, clog2f, clog2l \- base-2 logarithm of a complex number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex clog2(double complex " z );
+.BI "float complex clog2f(float complex " z );
+.BI "long double complex clog2l(long double complex " z );
+.fi
+.SH DESCRIPTION
+The call
+.I clog2(z)
+is equivalent to
+.IR clog(z)/log(2) .
+.P
+The other functions perform the same task for
+.I float
+and
+.IR "long double" .
+.P
+Note that
+.I z
+close to zero will cause an overflow.
+.SH STANDARDS
+None.
+.SH HISTORY
+These function names are reserved for future use in C99.
+.P
+Not yet in glibc, as at glibc 2.19.
+.\" But reserved in NAMESPACE.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cexp (3),
+.BR clog (3),
+.BR clog10 (3),
+.BR complex (7)
diff --git a/man/man3/clog2f.3 b/man/man3/clog2f.3
new file mode 100644
index 000000000..23d683416
--- /dev/null
+++ b/man/man3/clog2f.3
@@ -0,0 +1 @@
+.so man3/clog2.3
diff --git a/man/man3/clog2l.3 b/man/man3/clog2l.3
new file mode 100644
index 000000000..23d683416
--- /dev/null
+++ b/man/man3/clog2l.3
@@ -0,0 +1 @@
+.so man3/clog2.3
diff --git a/man/man3/clogf.3 b/man/man3/clogf.3
new file mode 100644
index 000000000..3cd9533b3
--- /dev/null
+++ b/man/man3/clogf.3
@@ -0,0 +1 @@
+.so man3/clog.3
diff --git a/man/man3/clogl.3 b/man/man3/clogl.3
new file mode 100644
index 000000000..3cd9533b3
--- /dev/null
+++ b/man/man3/clogl.3
@@ -0,0 +1 @@
+.so man3/clog.3
diff --git a/man/man3/closedir.3 b/man/man3/closedir.3
new file mode 100644
index 000000000..6526a27be
--- /dev/null
+++ b/man/man3/closedir.3
@@ -0,0 +1,75 @@
+'\" t
+.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 21:25:52 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 11 June 1995 by Andries Brouwer (aeb@cwi.nl)
+.TH closedir 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+closedir \- close a directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <dirent.h>
+.P
+.BI "int closedir(DIR *" dirp );
+.fi
+.SH DESCRIPTION
+The
+.BR closedir ()
+function closes the directory stream associated with
+.IR dirp .
+A successful call to
+.BR closedir ()
+also closes the underlying file descriptor associated with
+.IR dirp .
+The directory stream descriptor
+.I dirp
+is not available
+after this call.
+.SH RETURN VALUE
+The
+.BR closedir ()
+function returns 0 on success.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+Invalid directory stream descriptor
+.IR dirp .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR closedir ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR close (2),
+.BR opendir (3),
+.BR readdir (3),
+.BR rewinddir (3),
+.BR scandir (3),
+.BR seekdir (3),
+.BR telldir (3)
diff --git a/man/man3/closelog.3 b/man/man3/closelog.3
new file mode 100644
index 000000000..ec352b291
--- /dev/null
+++ b/man/man3/closelog.3
@@ -0,0 +1 @@
+.so man3/syslog.3
diff --git a/man/man3/cmsg.3 b/man/man3/cmsg.3
new file mode 100644
index 000000000..43fd7c176
--- /dev/null
+++ b/man/man3/cmsg.3
@@ -0,0 +1,261 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: cmsg.3,v 1.8 2000/12/20 18:10:31 ak Exp $
+.TH CMSG 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+CMSG_ALIGN, CMSG_SPACE, CMSG_NXTHDR, CMSG_FIRSTHDR \- access ancillary data
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "struct cmsghdr *CMSG_FIRSTHDR(struct msghdr *" msgh );
+.BI "struct cmsghdr *CMSG_NXTHDR(struct msghdr *" msgh ,
+.BR "                            struct cmsghdr *" cmsg );
+.BI "size_t CMSG_ALIGN(size_t " length );
+.BI "size_t CMSG_SPACE(size_t " length );
+.BI "size_t CMSG_LEN(size_t " length );
+.BI "unsigned char *CMSG_DATA(struct cmsghdr *" cmsg );
+.fi
+.SH DESCRIPTION
+These macros are used to create and access control messages (also called
+ancillary data) that are not a part of the socket payload.
+This control information may
+include the interface the packet was received on, various rarely used header
+fields, an extended error description, a set of file descriptors, or UNIX
+credentials.
+For instance, control messages can be used to send
+additional header fields such as IP options.
+Ancillary data is sent by calling
+.BR sendmsg (2)
+and received by calling
+.BR recvmsg (2).
+See their manual pages for more information.
+.P
+Ancillary data is a sequence of
+.I cmsghdr
+structures with appended data.
+See the specific protocol man pages for the available control message types.
+The maximum ancillary buffer size allowed per socket can be set using
+.IR /proc/sys/net/core/optmem_max ;
+see
+.BR socket (7).
+.P
+The
+.I cmsghdr
+structure is defined as follows:
+.P
+.in +4n
+.EX
+struct cmsghdr {
+    size_t cmsg_len;    /* Data byte count, including header
+                           (type is socklen_t in POSIX) */
+    int    cmsg_level;  /* Originating protocol */
+    int    cmsg_type;   /* Protocol\-specific type */
+/* followed by
+   unsigned char cmsg_data[]; */
+};
+.EE
+.in
+.P
+The sequence of
+.I cmsghdr
+structures should never be accessed directly.
+Instead, use only the following macros:
+.TP
+.BR CMSG_FIRSTHDR ()
+returns a pointer to the first
+.I cmsghdr
+in the ancillary
+data buffer associated with the passed
+.IR msghdr .
+It returns NULL if there isn't enough space for a
+.I cmsghdr
+in the buffer.
+.TP
+.BR CMSG_NXTHDR ()
+returns the next valid
+.I cmsghdr
+after the passed
+.IR cmsghdr .
+It returns NULL when there isn't enough space left in the buffer.
+.IP
+When initializing a buffer that will contain a series of
+.I cmsghdr
+structures (e.g., to be sent with
+.BR sendmsg (2)),
+that buffer should first be zero-initialized
+to ensure the correct operation of
+.BR CMSG_NXTHDR ().
+.TP
+.BR CMSG_ALIGN (),
+given a length, returns it including the required alignment.
+This is a
+constant expression.
+.TP
+.BR CMSG_SPACE ()
+returns the number of bytes an ancillary element with payload of the
+passed data length occupies.
+This is a constant expression.
+.TP
+.BR CMSG_DATA ()
+returns a pointer to the data portion of a
+.IR cmsghdr .
+The pointer returned cannot be assumed to be suitably aligned for
+accessing arbitrary payload data types.
+Applications should not cast it to a pointer type matching the payload,
+but should instead use
+.BR memcpy (3)
+to copy data to or from a suitably declared object.
+.TP
+.BR CMSG_LEN ()
+returns the value to store in the
+.I cmsg_len
+member of the
+.I cmsghdr
+structure, taking into account any necessary
+alignment.
+It takes the data length as an argument.
+This is a constant
+expression.
+.P
+To create ancillary data, first initialize the
+.I msg_controllen
+member of the
+.I msghdr
+with the length of the control message buffer.
+Use
+.BR CMSG_FIRSTHDR ()
+on the
+.I msghdr
+to get the first control message and
+.BR CMSG_NXTHDR ()
+to get all subsequent ones.
+In each control message, initialize
+.I cmsg_len
+(with
+.BR CMSG_LEN ()),
+the other
+.I cmsghdr
+header fields, and the data portion using
+.BR CMSG_DATA ().
+Finally, the
+.I msg_controllen
+field of the
+.I msghdr
+should be set to the sum of the
+.BR CMSG_SPACE ()
+of the length of
+all control messages in the buffer.
+For more information on the
+.IR msghdr ,
+see
+.BR recvmsg (2).
+.SH VERSIONS
+For portability, ancillary data should be accessed using only the macros
+described here.
+.P
+In Linux,
+.BR CMSG_LEN (),
+.BR CMSG_DATA (),
+and
+.BR CMSG_ALIGN ()
+are constant expressions (assuming their argument is constant),
+meaning that these values can be used to declare the size of global variables.
+This may not be portable, however.
+.SH STANDARDS
+.TP
+.BR CMSG_FIRSTHDR ()
+.TQ
+.BR CMSG_NXTHDR ()
+.TQ
+.BR CMSG_DATA ()
+POSIX.1-2008.
+.TP
+.BR CMSG_SPACE ()
+.TQ
+.BR CMSG_LEN ()
+.TQ
+.BR CMSG_ALIGN ()
+Linux.
+.SH HISTORY
+This ancillary data model conforms to the POSIX.1g draft, 4.4BSD-Lite,
+the IPv6 advanced API described in RFC\ 2292 and SUSv2.
+.P
+.BR CMSG_SPACE ()
+and
+.BR CMSG_LEN ()
+.\" https://www.austingroupbugs.net/view.php?id=978#c3242
+will be included in the next POSIX release (Issue 8).
+.SH EXAMPLES
+This code looks for the
+.B IP_TTL
+option in a received ancillary buffer:
+.P
+.in +4n
+.EX
+struct msghdr msgh;
+struct cmsghdr *cmsg;
+int received_ttl;
+\&
+/* Receive auxiliary data in msgh */
+\&
+for (cmsg = CMSG_FIRSTHDR(&msgh); cmsg != NULL;
+        cmsg = CMSG_NXTHDR(&msgh, cmsg)) {
+    if (cmsg\->cmsg_level == IPPROTO_IP
+            && cmsg\->cmsg_type == IP_TTL) {
+        memcpy(&receive_ttl, CMSG_DATA(cmsg), sizeof(received_ttl));
+        break;
+    }
+}
+\&
+if (cmsg == NULL) {
+    /* Error: IP_TTL not enabled or small buffer or I/O error */
+}
+.EE
+.in
+.P
+The code below passes an array of file descriptors over a
+UNIX domain socket using
+.BR SCM_RIGHTS :
+.P
+.in +4n
+.EX
+struct msghdr msg = { 0 };
+struct cmsghdr *cmsg;
+int myfds[NUM_FD];  /* Contains the file descriptors to pass */
+char iobuf[1];
+struct iovec io = {
+    .iov_base = iobuf,
+    .iov_len = sizeof(iobuf)
+};
+union {         /* Ancillary data buffer, wrapped in a union
+                   in order to ensure it is suitably aligned */
+    char buf[CMSG_SPACE(sizeof(myfds))];
+    struct cmsghdr align;
+} u;
+\&
+msg.msg_iov = &io;
+msg.msg_iovlen = 1;
+msg.msg_control = u.buf;
+msg.msg_controllen = sizeof(u.buf);
+cmsg = CMSG_FIRSTHDR(&msg);
+cmsg\->cmsg_level = SOL_SOCKET;
+cmsg\->cmsg_type = SCM_RIGHTS;
+cmsg\->cmsg_len = CMSG_LEN(sizeof(myfds));
+memcpy(CMSG_DATA(cmsg), myfds, sizeof(myfds));
+.EE
+.in
+.P
+For a complete code example that shows passing of file descriptors
+over a UNIX domain socket, see
+.BR seccomp_unotify (2).
+.SH SEE ALSO
+.BR recvmsg (2),
+.BR sendmsg (2)
+.P
+RFC\ 2292
diff --git a/man/man3/confstr.3 b/man/man3/confstr.3
new file mode 100644
index 000000000..5cb924cf0
--- /dev/null
+++ b/man/man3/confstr.3
@@ -0,0 +1,156 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 19:53:02 1993 by Rik Faith (faith@cs.unc.edu)
+.\"
+.\" FIXME Many more values for 'name' are supported, some of which
+.\" are documented under 'info libc confstr'.
+.\" See <bits/confname.h> for the rest.
+.\" These should all be added to this page.
+.\" See also the POSIX.1-2001 specification of confstr()
+.\"
+.TH confstr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+confstr \- get configuration dependent string variables
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "size_t confstr(int " "name" ", char " buf [. size "], size_t " size );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR confstr ():
+.nf
+    _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+.BR confstr ()
+gets the value of configuration-dependent string variables.
+.P
+The
+.I name
+argument is the system variable to be queried.
+The following variables are supported:
+.TP
+.BR _CS_GNU_LIBC_VERSION " (GNU C library only; since glibc 2.3.2)"
+A string which identifies the GNU C library version on this system
+(e.g., "glibc 2.3.4").
+.TP
+.BR _CS_GNU_LIBPTHREAD_VERSION " (GNU C library only; since glibc 2.3.2)"
+A string which identifies the POSIX implementation supplied by this
+C library (e.g., "NPTL 2.3.4" or "linuxthreads\-0.10").
+.TP
+.B _CS_PATH
+A value for the
+.B PATH
+variable which indicates where all the POSIX.2 standard utilities can
+be found.
+.P
+If
+.I buf
+is not NULL and
+.I size
+is not zero,
+.BR confstr ()
+copies the value of the string to
+.I buf
+truncated to
+.I size \- 1
+bytes if necessary, with a null byte (\[aq]\e0\[aq]) as terminator.
+This can be detected by comparing the return value of
+.BR confstr ()
+against
+.IR size .
+.P
+If
+.I size
+is zero and
+.I buf
+is NULL,
+.BR confstr ()
+just returns the value as defined below.
+.SH RETURN VALUE
+If
+.I name
+is a valid configuration variable,
+.BR confstr ()
+returns the number of bytes (including the terminating null byte)
+that would be required to hold the entire value of that variable.
+This value may be greater than
+.IR size ,
+which means that the value in
+.I buf
+is truncated.
+.P
+If
+.I name
+is a valid configuration variable,
+but that variable does not have a value, then
+.BR confstr ()
+returns 0.
+If
+.I name
+does not correspond to a valid configuration variable,
+.BR confstr ()
+returns 0, and
+.I errno
+is set to
+.BR EINVAL .
+.SH ERRORS
+.TP
+.B EINVAL
+The value of
+.I name
+is invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR confstr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+The following code fragment determines the path where to find
+the POSIX.2 system utilities:
+.P
+.in +4n
+.EX
+char *pathbuf;
+size_t n;
+\&
+n = confstr(_CS_PATH, NULL, (size_t) 0);
+pathbuf = malloc(n);
+if (pathbuf == NULL)
+    abort();
+confstr(_CS_PATH, pathbuf, n);
+.EE
+.in
+.SH SEE ALSO
+.BR getconf (1),
+.BR sh (1),
+.BR exec (3),
+.BR fpathconf (3),
+.BR pathconf (3),
+.BR sysconf (3),
+.BR system (3)
diff --git a/man/man3/conj.3 b/man/man3/conj.3
new file mode 100644
index 000000000..36bf2ea70
--- /dev/null
+++ b/man/man3/conj.3
@@ -0,0 +1,56 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH conj 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+conj, conjf, conjl \- calculate the complex conjugate
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex conj(double complex " z );
+.BI "float complex conjf(float complex " z );
+.BI "long double complex conjl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions return the complex conjugate value of
+.IR z .
+That is the value obtained by changing the sign of the imaginary part.
+.P
+One has:
+.P
+.in +4n
+.EX
+cabs(z) = csqrt(z * conj(z))
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR conj (),
+.BR conjf (),
+.BR conjl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR csqrt (3),
+.BR complex (7)
diff --git a/man/man3/conjf.3 b/man/man3/conjf.3
new file mode 100644
index 000000000..ef6093f70
--- /dev/null
+++ b/man/man3/conjf.3
@@ -0,0 +1 @@
+.so man3/conj.3
diff --git a/man/man3/conjl.3 b/man/man3/conjl.3
new file mode 100644
index 000000000..ef6093f70
--- /dev/null
+++ b/man/man3/conjl.3
@@ -0,0 +1 @@
+.so man3/conj.3
diff --git a/man/man3/copysign.3 b/man/man3/copysign.3
new file mode 100644
index 000000000..bf20466ae
--- /dev/null
+++ b/man/man3/copysign.3
@@ -0,0 +1,92 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-08-10 by Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.TH copysign 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+copysign, copysignf, copysignl \- copy sign of a number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double copysign(double " x ", double " y );
+.BI "float copysignf(float " x ", float " y );
+.BI "long double copysignl(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR copysign (),
+.BR copysignf (),
+.BR copysignl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return a value whose absolute value matches that of
+.IR x ,
+but whose sign bit matches that of
+.IR y .
+.P
+For example,
+.I "copysign(42.0,\ \-1.0)"
+and
+.I "copysign(\-42.0, \-1.0)"
+both return \-42.0.
+.SH RETURN VALUE
+On success, these functions return a value whose magnitude is taken from
+.I x
+and whose sign is taken from
+.IR y .
+.P
+If
+.I x
+is a NaN,
+a NaN with the sign bit of
+.I y
+is returned.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR copysign (),
+.BR copysignf (),
+.BR copysignl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On architectures where the floating-point formats are not IEEE 754 compliant,
+these functions may treat a negative zero as positive.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.P
+This function is defined in IEC 559 (and the appendix with
+recommended functions in IEEE 754/IEEE 854).
+.SH HISTORY
+C99, POSIX.1-2001, 4.3BSD.
+.SH SEE ALSO
+.BR signbit (3)
diff --git a/man/man3/copysignf.3 b/man/man3/copysignf.3
new file mode 100644
index 000000000..46ef5e6db
--- /dev/null
+++ b/man/man3/copysignf.3
@@ -0,0 +1 @@
+.so man3/copysign.3
diff --git a/man/man3/copysignl.3 b/man/man3/copysignl.3
new file mode 100644
index 000000000..46ef5e6db
--- /dev/null
+++ b/man/man3/copysignl.3
@@ -0,0 +1 @@
+.so man3/copysign.3
diff --git a/man/man3/cos.3 b/man/man3/cos.3
new file mode 100644
index 000000000..4df1ae43c
--- /dev/null
+++ b/man/man3/cos.3
@@ -0,0 +1,118 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.TH cos 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cos, cosf, cosl \- cosine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double cos(double " x );
+.BI "float cosf(float " x );
+.BI "long double cosl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR cosf (),
+.BR cosl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the cosine of
+.IR x ,
+where
+.I x
+is
+given in radians.
+.SH RETURN VALUE
+On success, these functions return the cosine of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is positive infinity or negative infinity,
+a domain error occurs,
+and a NaN is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is an infinity
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cos (),
+.BR cosf (),
+.BR cosl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH BUGS
+Before glibc 2.10, the glibc implementation did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6780
+.I errno
+to
+.B EDOM
+when a domain error occurred.
+.SH SEE ALSO
+.BR acos (3),
+.BR asin (3),
+.BR atan (3),
+.BR atan2 (3),
+.BR ccos (3),
+.BR sin (3),
+.BR sincos (3),
+.BR tan (3)
diff --git a/man/man3/cosf.3 b/man/man3/cosf.3
new file mode 100644
index 000000000..9abaea4b0
--- /dev/null
+++ b/man/man3/cosf.3
@@ -0,0 +1 @@
+.so man3/cos.3
diff --git a/man/man3/cosh.3 b/man/man3/cosh.3
new file mode 100644
index 000000000..4a22227d7
--- /dev/null
+++ b/man/man3/cosh.3
@@ -0,0 +1,130 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1996-06-08 by aeb
+.\" Modified 2002-07-27 by Walter Harms
+.\" (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH cosh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cosh, coshf, coshl \- hyperbolic cosine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double cosh(double " x );
+.BI "float coshf(float " x );
+.BI "long double coshl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR coshf (),
+.BR coshl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the hyperbolic cosine of
+.IR x ,
+which is defined mathematically as:
+.P
+.in +4n
+.EX
+cosh(x) = (exp(x) + exp(\-x)) / 2
+.EE
+.in
+.SH RETURN VALUE
+On success, these functions return the hyperbolic cosine of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 or \-0, 1 is returned.
+.P
+If
+.I x
+is positive infinity or negative infinity,
+positive infinity is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.RB + HUGE_VAL ,
+.RB + HUGE_VALF ,
+or
+.RB + HUGE_VALL ,
+respectively.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cosh (),
+.BR coshf (),
+.BR coshl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH BUGS
+In glibc 2.3.4 and earlier,
+an overflow floating-point
+.RB ( FE_OVERFLOW  )
+exception is not raised when an overflow occurs.
+.SH SEE ALSO
+.BR acosh (3),
+.BR asinh (3),
+.BR atanh (3),
+.BR ccos (3),
+.BR sinh (3),
+.BR tanh (3)
diff --git a/man/man3/coshf.3 b/man/man3/coshf.3
new file mode 100644
index 000000000..e9bab10c7
--- /dev/null
+++ b/man/man3/coshf.3
@@ -0,0 +1 @@
+.so man3/cosh.3
diff --git a/man/man3/coshl.3 b/man/man3/coshl.3
new file mode 100644
index 000000000..e9bab10c7
--- /dev/null
+++ b/man/man3/coshl.3
@@ -0,0 +1 @@
+.so man3/cosh.3
diff --git a/man/man3/cosl.3 b/man/man3/cosl.3
new file mode 100644
index 000000000..9abaea4b0
--- /dev/null
+++ b/man/man3/cosl.3
@@ -0,0 +1 @@
+.so man3/cos.3
diff --git a/man/man3/cpow.3 b/man/man3/cpow.3
new file mode 100644
index 000000000..341c29b72
--- /dev/null
+++ b/man/man3/cpow.3
@@ -0,0 +1,53 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cpow 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cpow, cpowf, cpowl \- complex power function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex cpow(double complex " x ", double complex " z );
+.BI "float complex cpowf(float complex " x ", float complex " z );
+.BI "long double complex cpowl(long double complex " x ,
+.BI "                          long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate
+.I x
+raised to the power
+.I z
+(with a branch cut for
+.I x
+along the negative real axis).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cpow (),
+.BR cpowf (),
+.BR cpowl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR pow (3),
+.BR complex (7)
diff --git a/man/man3/cpowf.3 b/man/man3/cpowf.3
new file mode 100644
index 000000000..7577fcdf1
--- /dev/null
+++ b/man/man3/cpowf.3
@@ -0,0 +1 @@
+.so man3/cpow.3
diff --git a/man/man3/cpowl.3 b/man/man3/cpowl.3
new file mode 100644
index 000000000..7577fcdf1
--- /dev/null
+++ b/man/man3/cpowl.3
@@ -0,0 +1 @@
+.so man3/cpow.3
diff --git a/man/man3/cproj.3 b/man/man3/cproj.3
new file mode 100644
index 000000000..f91d43214
--- /dev/null
+++ b/man/man3/cproj.3
@@ -0,0 +1,59 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH cproj 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cproj, cprojf, cprojl \- project into Riemann Sphere
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex cproj(double complex " z ");"
+.BI "float complex cprojf(float complex " z ");"
+.BI "long double complex cprojl(long double complex " z ");"
+.fi
+.SH DESCRIPTION
+These functions project a point in the plane onto the surface of a
+Riemann Sphere, the one-point compactification of the complex plane.
+Each finite point
+.I z
+projects to
+.I z
+itself.
+Every complex infinite value is projected to a single infinite value,
+namely to positive infinity on the real axis.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR cproj (),
+.BR cprojf (),
+.BR cprojl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.P
+In glibc 2.11 and earlier, the implementation does something different
+(a
+.I stereographic
+projection onto a Riemann Sphere).
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=10401
+.SH SEE ALSO
+.BR cabs (3),
+.BR complex (7)
diff --git a/man/man3/cprojf.3 b/man/man3/cprojf.3
new file mode 100644
index 000000000..0a3f31c6d
--- /dev/null
+++ b/man/man3/cprojf.3
@@ -0,0 +1 @@
+.so man3/cproj.3
diff --git a/man/man3/cprojl.3 b/man/man3/cprojl.3
new file mode 100644
index 000000000..0a3f31c6d
--- /dev/null
+++ b/man/man3/cprojl.3
@@ -0,0 +1 @@
+.so man3/cproj.3
diff --git a/man/man3/creal.3 b/man/man3/creal.3
new file mode 100644
index 000000000..97848d500
--- /dev/null
+++ b/man/man3/creal.3
@@ -0,0 +1,56 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH creal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+creal, crealf, creall \- get real part of a complex number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double creal(double complex " z );
+.BI "float crealf(float complex " z );
+.BI "long double creall(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions return the real part of the complex number
+.IR z .
+.P
+One has:
+.P
+.nf
+    z = creal(z) + I * cimag(z)
+.fi
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR creal (),
+.BR crealf (),
+.BR creall ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+GCC supports also __real__.
+That is a GNU extension.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cimag (3),
+.BR complex (7)
diff --git a/man/man3/crealf.3 b/man/man3/crealf.3
new file mode 100644
index 000000000..4289f71de
--- /dev/null
+++ b/man/man3/crealf.3
@@ -0,0 +1 @@
+.so man3/creal.3
diff --git a/man/man3/creall.3 b/man/man3/creall.3
new file mode 100644
index 000000000..4289f71de
--- /dev/null
+++ b/man/man3/creall.3
@@ -0,0 +1 @@
+.so man3/creal.3
diff --git a/man/man3/crypt.3 b/man/man3/crypt.3
new file mode 100644
index 000000000..b619149a1
--- /dev/null
+++ b/man/man3/crypt.3
@@ -0,0 +1,319 @@
+'\" t
+.\" Michael Haardt (michael@cantor.informatik.rwth.aachen.de)
+.\"     Sat Sep  3 22:00:30 MET DST 1994
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Sun Feb 19 21:32:25 1995, faith@cs.unc.edu edited details away
+.\"
+.\" TO DO: This manual page should go more into detail how DES is perturbed,
+.\" which string will be encrypted, and what determines the repetition factor.
+.\" Is a simple repetition using ECB used, or something more advanced?  I hope
+.\" the presented explanations are at least better than nothing, but by no
+.\" means enough.
+.\"
+.\" added _XOPEN_SOURCE, aeb, 970705
+.\" added GNU MD5 stuff, aeb, 011223
+.\"
+.TH crypt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+crypt, crypt_r \- password hashing
+.SH LIBRARY
+Password hashing library
+.RI ( libcrypt ", " \-lcrypt )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "char *crypt(const char *" key ", const char *" salt );
+.P
+.B #include <crypt.h>
+.P
+.BI "char *crypt_r(const char *" key ", const char *" salt ,
+.BI "              struct crypt_data *restrict " data );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR crypt ():
+.nf
+    Since glibc 2.28:
+        _DEFAULT_SOURCE
+    glibc 2.27 and earlier:
+        _XOPEN_SOURCE
+.fi
+.P
+.BR crypt_r ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.BR crypt ()
+is the password hashing function.
+It is based on the Data Encryption
+Standard algorithm with variations intended (among other things) to
+discourage use of hardware implementations of a key search.
+.P
+.I key
+is a user's typed password.
+.P
+.I salt
+is a two-character string chosen from the set
+[\fBa\-zA\-Z0\-9./\fP].
+This string is used to
+perturb the algorithm in one of 4096 different ways.
+.P
+By taking the lowest 7 bits of each of the first eight characters of the
+.IR key ,
+a 56-bit key is obtained.
+This 56-bit key is used to encrypt repeatedly a
+constant string (usually a string consisting of all zeros).
+The returned
+value points to the hashed password, a series of 13 printable ASCII
+characters (the first two characters represent the salt itself).
+The return value points to static data whose content is
+overwritten by each call.
+.P
+Warning: the key space consists of
+.if t 2\s-2\u56\s0\d
+.if n 2**56
+equal 7.2e16 possible values.
+Exhaustive searches of this key space are
+possible using massively parallel computers.
+Software, such as
+.BR crack (1),
+is available which will search the portion of this key space that is
+generally used by humans for passwords.
+Hence, password selection should,
+at minimum, avoid common words and names.
+The use of a
+.BR passwd (1)
+program that checks for crackable passwords during the selection process is
+recommended.
+.P
+The DES algorithm itself has a few quirks which make the use of the
+.BR crypt ()
+interface a very poor choice for anything other than password
+authentication.
+If you are planning on using the
+.BR crypt ()
+interface for a cryptography project, don't do it: get a good book on
+encryption and one of the widely available DES libraries.
+.P
+.BR crypt_r ()
+is a reentrant version of
+.BR crypt ().
+The structure pointed to by
+.I data
+is used to store result data and bookkeeping information.
+Other than allocating it,
+the only thing that the caller should do with this structure is to set
+.I data\->initialized
+to zero before the first call to
+.BR crypt_r ().
+.SH RETURN VALUE
+On success, a pointer to the hashed password is returned.
+On error, NULL is returned.
+.SH ERRORS
+.TP
+.B EINVAL
+.I salt
+has the wrong format.
+.TP
+.B ENOSYS
+The
+.BR crypt ()
+function was not implemented, probably because of U.S.A. export restrictions.
+.\" This level of detail is not necessary in this man page. . .
+.\" .P
+.\" When encrypting a plain text P using DES with the key K results in the
+.\" encrypted text C, then the complementary plain text P' being encrypted
+.\" using the complementary key K' will result in the complementary encrypted
+.\" text C'.
+.\" .P
+.\" Weak keys are keys which stay invariant under the DES key transformation.
+.\" The four known weak keys 0101010101010101, fefefefefefefefe,
+.\" 1f1f1f1f0e0e0e0e and e0e0e0e0f1f1f1f1 must be avoided.
+.\" .P
+.\" There are six known half weak key pairs, which keys lead to the same
+.\" encrypted data.  Keys which are part of such key clusters should be
+.\" avoided.
+.\" Sorry, I could not find out what they are.
+.\""
+.\" .P
+.\" Heavily redundant data causes trouble with DES encryption, when used in the
+.\" .I codebook
+.\" mode that
+.\" .BR crypt ()
+.\" implements.  The
+.\" .BR crypt ()
+.\" interface should be used only for its intended purpose of password
+.\" verification, and should not be used as part of a data encryption tool.
+.\" .P
+.\" The first and last three output bits of the fourth S-box can be
+.\" represented as function of their input bits.  Empiric studies have
+.\" shown that S-boxes partially compute the same output for similar input.
+.\" It is suspected that this may contain a back door which could allow the
+.\" NSA to decrypt DES encrypted data.
+.\" .P
+.\" Making encrypted data computed using crypt() publicly available has
+.\" to be considered insecure for the given reasons.
+.TP
+.B EPERM
+.I /proc/sys/crypto/fips_enabled
+has a nonzero value,
+and an attempt was made to use a weak hashing type, such as DES.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR crypt ()
+T}	Thread safety	MT-Unsafe race:crypt
+T{
+.na
+.nh
+.BR crypt_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR crypt ()
+POSIX.1-2008.
+.TP
+.BR crypt_r ()
+GNU.
+.SH HISTORY
+.TP
+.BR crypt ()
+POSIX.1-2001, SVr4, 4.3BSD.
+.SS Availability in glibc
+The
+.BR crypt (),
+.BR encrypt (3),
+and
+.BR setkey (3)
+functions are part of the POSIX.1-2008 XSI Options Group for Encryption
+and are optional.
+If the interfaces are not available, then the symbolic constant
+.B _XOPEN_CRYPT
+is either not defined,
+or it is defined to \-1 and availability can be checked at run time with
+.BR sysconf (3).
+This may be the case if the downstream distribution has switched from glibc
+crypt to
+.IR libxcrypt .
+When recompiling applications in such distributions,
+the programmer must detect if
+.B _XOPEN_CRYPT
+is not available and include
+.I <crypt.h>
+for the function prototypes;
+otherwise
+.I libxcrypt
+is an ABI-compatible drop-in replacement.
+.SH NOTES
+.SS Features in glibc
+The glibc version of this function supports additional
+hashing algorithms.
+.P
+If
+.I salt
+is a character string starting with the characters "$\fIid\fP$"
+followed by a string optionally terminated by "$",
+then the result has the form:
+.RS
+.P
+$\fIid\fP$\fIsalt\fP$\fIhashed\fP
+.RE
+.P
+.I id
+identifies the hashing method used instead of DES and this
+then determines how the rest of the password string is interpreted.
+The following values of
+.I id
+are supported:
+.RS
+.TS
+lb lb
+l lx.
+ID	Method
+_
+1	MD5
+2a	T{
+Blowfish (not in mainline glibc; added in some
+Linux distributions)
+T}
+.\" openSUSE has Blowfish, but AFAICS, this option is not supported
+.\" natively by glibc -- mtk, Jul 08
+.\"
+.\" md5 | Sun MD5
+.\" glibc doesn't appear to natively support Sun MD5; I don't know
+.\" if any distros add the support.
+5	SHA-256 (since glibc 2.7)
+6	SHA-512 (since glibc 2.7)
+.TE
+.RE
+.P
+Thus, $5$\fIsalt\fP$\fIhashed\fP and $6$\fIsalt\fP$\fIhashed\fP
+contain the password hashed with, respectively, functions
+based on SHA-256 and SHA-512.
+.P
+"\fIsalt\fP" stands for the up to 16 characters
+following "$\fIid\fP$" in the salt.
+The "\fIhashed\fP"
+part of the password string is the actual computed password.
+The size of this string is fixed:
+.RS
+.TS
+lb l.
+MD5	22 characters
+SHA-256	43 characters
+SHA-512	86 characters
+.TE
+.RE
+.P
+The characters in "\fIsalt\fP" and "\fIhashed\fP" are drawn from the set
+[\fBa\-zA\-Z0\-9./\fP].
+In the MD5 and SHA implementations the entire
+.I key
+is significant (instead of only the first
+8 bytes in DES).
+.P
+Since glibc 2.7,
+.\" glibc commit 9425cb9eea6a62fc21d99aafe8a60f752b934b05
+the SHA-256 and SHA-512 implementations support a user-supplied number of
+hashing rounds, defaulting to 5000.
+If the "$\fIid\fP$" characters in the salt are
+followed by "rounds=\fIxxx\fP$", where \fIxxx\fP is an integer, then the
+result has the form
+.RS
+.P
+$\fIid\fP$\fIrounds=yyy\fP$\fIsalt\fP$\fIhashed\fP
+.RE
+.P
+where \fIyyy\fP is the number of hashing rounds actually used.
+The number of rounds actually used is 1000 if
+.I xxx
+is less than
+1000, 999999999 if
+.I xxx
+is greater than 999999999, and
+is equal to
+.I xxx
+otherwise.
+.SH SEE ALSO
+.BR login (1),
+.BR passwd (1),
+.BR encrypt (3),
+.BR getpass (3),
+.BR passwd (5)
diff --git a/man/man3/crypt_r.3 b/man/man3/crypt_r.3
new file mode 100644
index 000000000..3944ebd53
--- /dev/null
+++ b/man/man3/crypt_r.3
@@ -0,0 +1 @@
+.so man3/crypt.3
diff --git a/man/man3/csin.3 b/man/man3/csin.3
new file mode 100644
index 000000000..8dccebcd4
--- /dev/null
+++ b/man/man3/csin.3
@@ -0,0 +1,57 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH csin 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+csin, csinf, csinl \- complex sine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex csin(double complex " z );
+.BI "float complex csinf(float complex " z );
+.BI "long double complex csinl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex sine of
+.IR z .
+.P
+The complex sine function is defined as:
+.P
+.in +4n
+.EX
+csin(z) = (exp(i * z) \- exp(\-i * z)) / (2 * i)
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR csin (),
+.BR csinf (),
+.BR csinl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR casin (3),
+.BR ccos (3),
+.BR ctan (3),
+.BR complex (7)
diff --git a/man/man3/csinf.3 b/man/man3/csinf.3
new file mode 100644
index 000000000..1ed2a3e7f
--- /dev/null
+++ b/man/man3/csinf.3
@@ -0,0 +1 @@
+.so man3/csin.3
diff --git a/man/man3/csinh.3 b/man/man3/csinh.3
new file mode 100644
index 000000000..709ae1af6
--- /dev/null
+++ b/man/man3/csinh.3
@@ -0,0 +1,57 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH csinh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+csinh, csinhf, csinhl \- complex hyperbolic sine
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex csinh(double complex " z );
+.BI "float complex csinhf(float complex " z );
+.BI "long double complex csinhl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex hyperbolic sine of
+.IR z .
+.P
+The complex hyperbolic sine function is defined as:
+.P
+.in +4n
+.EX
+csinh(z) = (exp(z)\-exp(\-z))/2
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR csinh (),
+.BR csinhf (),
+.BR csinhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR casinh (3),
+.BR ccosh (3),
+.BR ctanh (3),
+.BR complex (7)
diff --git a/man/man3/csinhf.3 b/man/man3/csinhf.3
new file mode 100644
index 000000000..9f6d66f92
--- /dev/null
+++ b/man/man3/csinhf.3
@@ -0,0 +1 @@
+.so man3/csinh.3
diff --git a/man/man3/csinhl.3 b/man/man3/csinhl.3
new file mode 100644
index 000000000..9f6d66f92
--- /dev/null
+++ b/man/man3/csinhl.3
@@ -0,0 +1 @@
+.so man3/csinh.3
diff --git a/man/man3/csinl.3 b/man/man3/csinl.3
new file mode 100644
index 000000000..1ed2a3e7f
--- /dev/null
+++ b/man/man3/csinl.3
@@ -0,0 +1 @@
+.so man3/csin.3
diff --git a/man/man3/csqrt.3 b/man/man3/csqrt.3
new file mode 100644
index 000000000..c29db36bd
--- /dev/null
+++ b/man/man3/csqrt.3
@@ -0,0 +1,51 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH csqrt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+csqrt, csqrtf, csqrtl \- complex square root
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex csqrt(double complex " z );
+.BI "float complex csqrtf(float complex " z );
+.BI "long double complex csqrtl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex square root of
+.IR z ,
+with a branch cut along the negative real axis.
+(That means that \fIcsqrt(\-1+eps*I)\fP will be close to I while
+\fIcsqrt(\-1\-eps*I)\fP will be close to \-I, \fIif eps\fP is a small positive
+real number.)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR csqrt (),
+.BR csqrtf (),
+.BR csqrtl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR cexp (3),
+.BR complex (7)
diff --git a/man/man3/csqrtf.3 b/man/man3/csqrtf.3
new file mode 100644
index 000000000..e3cf32905
--- /dev/null
+++ b/man/man3/csqrtf.3
@@ -0,0 +1 @@
+.so man3/csqrt.3
diff --git a/man/man3/csqrtl.3 b/man/man3/csqrtl.3
new file mode 100644
index 000000000..e3cf32905
--- /dev/null
+++ b/man/man3/csqrtl.3
@@ -0,0 +1 @@
+.so man3/csqrt.3
diff --git a/man/man3/ctan.3 b/man/man3/ctan.3
new file mode 100644
index 000000000..2bcfb58be
--- /dev/null
+++ b/man/man3/ctan.3
@@ -0,0 +1,57 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH ctan 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ctan, ctanf, ctanl \- complex tangent function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex ctan(double complex " z );
+.BI "float complex ctanf(float complex " z );
+.BI "long double complex ctanl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex tangent of
+.IR z .
+.P
+The complex tangent function is defined as:
+.P
+.in +4n
+.EX
+ctan(z) = csin(z) / ccos(z)
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ctan (),
+.BR ctanf (),
+.BR ctanl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR catan (3),
+.BR ccos (3),
+.BR csin (3),
+.BR complex (7)
diff --git a/man/man3/ctanf.3 b/man/man3/ctanf.3
new file mode 100644
index 000000000..c0f4a6607
--- /dev/null
+++ b/man/man3/ctanf.3
@@ -0,0 +1 @@
+.so man3/ctan.3
diff --git a/man/man3/ctanh.3 b/man/man3/ctanh.3
new file mode 100644
index 000000000..00ad505e7
--- /dev/null
+++ b/man/man3/ctanh.3
@@ -0,0 +1,58 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH ctanh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ctanh, ctanhf, ctanhl \- complex hyperbolic tangent
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.P
+.BI "double complex ctanh(double complex " z );
+.BI "float complex ctanhf(float complex " z );
+.BI "long double complex ctanhl(long double complex " z );
+.fi
+.SH DESCRIPTION
+These functions calculate the complex hyperbolic tangent of
+.IR z .
+.P
+The complex hyperbolic tangent function is defined
+mathematically as:
+.P
+.in +4n
+.EX
+ctanh(z) = csinh(z) / ccosh(z)
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ctanh (),
+.BR ctanhf (),
+.BR ctanhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR cabs (3),
+.BR catanh (3),
+.BR ccosh (3),
+.BR csinh (3),
+.BR complex (7)
diff --git a/man/man3/ctanhf.3 b/man/man3/ctanhf.3
new file mode 100644
index 000000000..49b92172b
--- /dev/null
+++ b/man/man3/ctanhf.3
@@ -0,0 +1 @@
+.so man3/ctanh.3
diff --git a/man/man3/ctanhl.3 b/man/man3/ctanhl.3
new file mode 100644
index 000000000..49b92172b
--- /dev/null
+++ b/man/man3/ctanhl.3
@@ -0,0 +1 @@
+.so man3/ctanh.3
diff --git a/man/man3/ctanl.3 b/man/man3/ctanl.3
new file mode 100644
index 000000000..c0f4a6607
--- /dev/null
+++ b/man/man3/ctanl.3
@@ -0,0 +1 @@
+.so man3/ctan.3
diff --git a/man/man3/ctermid.3 b/man/man3/ctermid.3
new file mode 100644
index 000000000..850dcec0b
--- /dev/null
+++ b/man/man3/ctermid.3
@@ -0,0 +1,73 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 19:51:06 1993 by Rik Faith (faith@cs.unc.edu)
+.TH ctermid 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ctermid \- get controlling terminal name
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.\" POSIX also requires this function to be declared in <unistd.h>,
+.\" and glibc does so if suitable feature test macros are defined.
+.P
+.BI "char *ctermid(char *" "s" );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ctermid ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+.BR ctermid ()
+returns a string which is the pathname for the current
+controlling terminal for this process.
+If
+.I s
+is NULL,
+a static buffer is used, otherwise
+.I s
+points to a buffer used to hold the terminal pathname.
+The symbolic constant
+.B L_ctermid
+is the maximum number of characters in the returned pathname.
+.SH RETURN VALUE
+The pointer to the pathname.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ctermid ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, Svr4.
+.SH BUGS
+The returned pathname may not uniquely identify the controlling
+terminal; it may, for example, be
+.IR /dev/tty .
+.P
+It is not assured that the program can open the terminal.
+.\" in glibc 2.3.x, x >= 4, the glibc headers threw an error
+.\" if ctermid() was given an argument; fixed in glibc 2.4.
+.SH SEE ALSO
+.BR ttyname (3)
diff --git a/man/man3/ctime.3 b/man/man3/ctime.3
new file mode 100644
index 000000000..b8543a1cf
--- /dev/null
+++ b/man/man3/ctime.3
@@ -0,0 +1,429 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:49:27 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Apr 26 12:38:55 MET DST 1996 by Martin Schulze (joey@linux.de)
+.\" Modified 2001-11-13, aeb
+.\" Modified 2001-12-13, joey, aeb
+.\" Modified 2004-11-16, mtk
+.\"
+.TH ctime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+asctime, ctime, gmtime, localtime, mktime, asctime_r, ctime_r, gmtime_r,
+localtime_r \- transform date and time to broken-down time or ASCII
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "char *asctime(const struct tm *" tm );
+.BI "char *asctime_r(const struct tm *restrict " tm ,
+.BI "                    char " buf "[restrict 26]);"
+.P
+.BI "char *ctime(const time_t *" timep );
+.BI "char *ctime_r(const time_t *restrict " timep ,
+.BI "                    char " buf "[restrict 26]);"
+.P
+.BI "struct tm *gmtime(const time_t *" timep );
+.BI "struct tm *gmtime_r(const time_t *restrict " timep ,
+.BI "                    struct tm *restrict " result );
+.P
+.BI "struct tm *localtime(const time_t *" timep );
+.BI "struct tm *localtime_r(const time_t *restrict " timep ,
+.BI "                    struct tm *restrict " result );
+.P
+.BI "time_t mktime(struct tm *" tm );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR asctime_r (),
+.BR ctime_r (),
+.BR gmtime_r (),
+.BR localtime_r ():
+.nf
+    _POSIX_C_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR ctime (),
+.BR gmtime (),
+and
+.BR localtime ()
+functions all take
+an argument of data type \fItime_t\fP, which represents calendar time.
+When interpreted as an absolute time value, it represents the number of
+seconds elapsed since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.P
+The
+.BR asctime ()
+and
+.BR mktime ()
+functions both take an argument
+representing broken-down time, which is a representation
+separated into year, month, day, and so on.
+.P
+Broken-down time is stored in the structure
+.IR tm ,
+described in
+.BR tm (3type).
+.P
+The call
+.BI ctime( t )
+is equivalent to
+.BI asctime(localtime( t )) \fR.
+It converts the calendar time \fIt\fP into a
+null-terminated string of the form
+.P
+.in +4n
+.EX
+"Wed Jun 30 21:49:08 1993\en"
+.EE
+.in
+.P
+The abbreviations for the days of the week are "Sun", "Mon", "Tue", "Wed",
+"Thu", "Fri", and "Sat".
+The abbreviations for the months are "Jan",
+"Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", and
+"Dec".
+The return value points to a statically allocated string which
+might be overwritten by subsequent calls to any of the date and time
+functions.
+The function also sets the external
+variables \fItzname\fP, \fItimezone\fP, and \fIdaylight\fP (see
+.BR tzset (3))
+with information about the current timezone.
+The reentrant version
+.BR ctime_r ()
+does the same, but stores the
+string in a user-supplied buffer
+which should have room for at least 26 bytes.
+It need not
+set \fItzname\fP, \fItimezone\fP, and \fIdaylight\fP.
+.P
+The
+.BR gmtime ()
+function converts the calendar time \fItimep\fP to
+broken-down time representation, expressed in Coordinated Universal Time
+(UTC).
+It may return NULL when the year does not fit into an integer.
+The return value points to a statically allocated struct which might be
+overwritten by subsequent calls to any of the date and time functions.
+The
+.BR gmtime_r ()
+function does the same, but stores the data in a
+user-supplied struct.
+.P
+The
+.BR localtime ()
+function converts the calendar time \fItimep\fP to
+broken-down time representation,
+expressed relative to the user's specified timezone.
+The function acts as if it called
+.BR tzset (3)
+and sets the external variables \fItzname\fP with
+information about the current timezone, \fItimezone\fP with the difference
+between Coordinated Universal Time (UTC) and local standard time in
+seconds, and \fIdaylight\fP to a nonzero value if daylight savings
+time rules apply during some part of the year.
+The return value points to a statically allocated struct which might be
+overwritten by subsequent calls to any of the date and time functions.
+The
+.BR localtime_r ()
+function does the same, but stores the data in a
+user-supplied struct.
+It need not set \fItzname\fP, \fItimezone\fP, and \fIdaylight\fP.
+.P
+The
+.BR asctime ()
+function converts the broken-down time value
+\fItm\fP into a null-terminated string with the same format as
+.BR ctime ().
+The return value points to a statically allocated string which might be
+overwritten by subsequent calls to any of the date and time functions.
+The
+.BR asctime_r ()
+function does the same, but stores the string in
+a user-supplied buffer which should have room for at least 26 bytes.
+.P
+The
+.BR mktime ()
+function converts a broken-down time structure, expressed
+as local time, to calendar time representation.
+The function ignores
+the values supplied by the caller in the
+.I tm_wday
+and
+.I tm_yday
+fields.
+The value specified in the
+.I tm_isdst
+field informs
+.BR mktime ()
+whether or not daylight saving time (DST)
+is in effect for the time supplied in the
+.I tm
+structure:
+a positive value means DST is in effect;
+zero means that DST is not in effect;
+and a negative value means that
+.BR mktime ()
+should (use timezone information and system databases to)
+attempt to determine whether DST is in effect at the specified time.
+.P
+The
+.BR mktime ()
+function modifies the fields of the
+.I tm
+structure as follows:
+.I tm_wday
+and
+.I tm_yday
+are set to values determined from the contents of the other fields;
+if structure members are outside their valid interval, they will be
+normalized (so that, for example, 40 October is changed into 9 November);
+.I tm_isdst
+is set (regardless of its initial value)
+to a positive value or to 0, respectively,
+to indicate whether DST is or is not in effect at the specified time.
+Calling
+.BR mktime ()
+also sets the external variable \fItzname\fP with
+information about the current timezone.
+.P
+If the specified broken-down
+time cannot be represented as calendar time (seconds since the Epoch),
+.BR mktime ()
+returns
+.I (time_t)\ \-1
+and does not alter the
+members of the broken-down time structure.
+.SH RETURN VALUE
+On success,
+.BR gmtime ()
+and
+.BR localtime ()
+return a pointer to a
+.IR "struct\ tm" .
+.P
+On success,
+.BR gmtime_r ()
+and
+.BR localtime_r ()
+return the address of the structure pointed to by
+.IR result .
+.P
+On success,
+.BR asctime ()
+and
+.BR ctime ()
+return a pointer to a string.
+.P
+On success,
+.BR asctime_r ()
+and
+.BR ctime_r ()
+return a pointer to the string pointed to by
+.IR buf .
+.P
+On success,
+.BR mktime ()
+returns the calendar time (seconds since the Epoch),
+expressed as a value of type
+.IR time_t .
+.P
+On error,
+.BR mktime ()
+returns the value
+.IR "(time_t)\ \-1" .
+The remaining functions return NULL on error.
+On error,
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EOVERFLOW
+The result cannot be represented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR asctime ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:asctime locale
+T}
+T{
+.na
+.nh
+.BR asctime_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe locale
+T}
+T{
+.na
+.nh
+.BR ctime ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:tmbuf
+race:asctime env locale
+T}
+T{
+.na
+.nh
+.BR ctime_r (),
+.BR gmtime_r (),
+.BR localtime_r (),
+.BR mktime ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe env locale
+T}
+T{
+.na
+.nh
+.BR gmtime (),
+.BR localtime ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:tmbuf env locale
+T}
+.TE
+.SH VERSIONS
+POSIX doesn't specify the parameters of
+.BR ctime_r ()
+to be
+.IR restrict ;
+that is specific to glibc.
+.P
+In many implementations, including glibc, a 0 in
+.I tm_mday
+is interpreted as meaning the last day of the preceding month.
+.P
+According to POSIX.1-2001,
+.BR localtime ()
+is required to behave as though
+.BR tzset (3)
+was called, while
+.BR localtime_r ()
+does not have this requirement.
+.\" See http://thread.gmane.org/gmane.comp.time.tz/2034/
+For portable code,
+.BR tzset (3)
+should be called before
+.BR localtime_r ().
+.SH STANDARDS
+.TP
+.BR asctime ()
+.TQ
+.BR ctime ()
+.TQ
+.BR gmtime ()
+.TQ
+.BR localtime ()
+.TQ
+.BR mktime ()
+C11, POSIX.1-2008.
+.TP
+.BR asctime_r ()
+.TQ
+.BR ctime_r ()
+.TQ
+.BR gmtime_r ()
+.TQ
+.BR localtime_r ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR gmtime ()
+.TQ
+.BR localtime ()
+.TQ
+.BR mktime ()
+C89, POSIX.1-2001.
+.TP
+.BR asctime ()
+.TQ
+.BR ctime ()
+C89, POSIX.1-2001.
+Marked obsolete in POSIX.1-2008 (recommending
+.BR strftime (3)).
+.TP
+.BR gmtime_r ()
+.TQ
+.BR localtime_r ()
+POSIX.1-2001.
+.TP
+.BR asctime_r ()
+.TQ
+.BR ctime_r ()
+POSIX.1-2001.
+Marked obsolete in POSIX.1-2008 (recommending
+.BR strftime (3)).
+.SH NOTES
+The four functions
+.BR asctime (),
+.BR ctime (),
+.BR gmtime (),
+and
+.BR localtime ()
+return a pointer to static data and hence are not thread-safe.
+The thread-safe versions,
+.BR asctime_r (),
+.BR ctime_r (),
+.BR gmtime_r (),
+and
+.BR localtime_r (),
+are specified by SUSv2.
+.P
+POSIX.1-2001 says:
+"The
+.BR asctime (),
+.BR ctime (),
+.BR gmtime (),
+and
+.BR localtime ()
+functions shall return values in one of two static objects:
+a broken-down time structure and an array of type
+.IR char .
+Execution of any of the functions may overwrite the information returned
+in either of these objects by any of the other functions."
+This can occur in the glibc implementation.
+.SH SEE ALSO
+.BR date (1),
+.BR gettimeofday (2),
+.BR time (2),
+.BR utime (2),
+.BR clock (3),
+.BR difftime (3),
+.BR strftime (3),
+.BR strptime (3),
+.BR timegm (3),
+.BR tzset (3),
+.BR time (7)
diff --git a/man/man3/ctime_r.3 b/man/man3/ctime_r.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/ctime_r.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/cuserid.3 b/man/man3/cuserid.3
new file mode 100644
index 000000000..b6d53bf72
--- /dev/null
+++ b/man/man3/cuserid.3
@@ -0,0 +1 @@
+.so man3/getlogin.3
diff --git a/man/man3/daemon.3 b/man/man3/daemon.3
new file mode 100644
index 000000000..edc4e54b6
--- /dev/null
+++ b/man/man3/daemon.3
@@ -0,0 +1,129 @@
+'\" t
+.\" Copyright (c) 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	@(#)daemon.3	8.1 (Berkeley) 6/9/93
+.\" Added mentioning of glibc weirdness wrt unistd.h. 5/11/98, Al Viro
+.TH daemon 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+daemon \- run in the background
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int daemon(int " nochdir ", int " noclose );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR daemon ():
+.nf
+    Since glibc 2.21:
+.\"             commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+The
+.BR daemon ()
+function is for programs wishing to detach themselves from the
+controlling terminal and run in the background as system daemons.
+.P
+If
+.I nochdir
+is zero,
+.BR daemon ()
+changes the process's current working directory
+to the root directory ("/");
+otherwise, the current working directory is left unchanged.
+.P
+If
+.I noclose
+is zero,
+.BR daemon ()
+redirects standard input, standard output, and standard error
+to
+.IR /dev/null ;
+otherwise, no changes are made to these file descriptors.
+.SH RETURN VALUE
+(This function forks, and if the
+.BR fork (2)
+succeeds, the parent calls
+.\" not .IR in order not to underline _
+.BR _exit (2),
+so that further errors are seen by the child only.)
+On success
+.BR daemon ()
+returns zero.
+If an error occurs,
+.BR daemon ()
+returns \-1 and sets
+.I errno
+to any of the errors specified for the
+.BR fork (2)
+and
+.BR setsid (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR daemon ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+A similar function appears on the BSDs.
+.P
+The glibc implementation can also return \-1 when
+.I /dev/null
+exists but is not a character device with the expected
+major and minor numbers.
+In this case,
+.I errno
+need not be set.
+.SH STANDARDS
+None.
+.SH HISTORY
+4.4BSD.
+.SH BUGS
+The GNU C library implementation of this function was taken from BSD,
+and does not employ the double-fork technique (i.e.,
+.BR fork (2),
+.BR setsid (2),
+.BR fork (2))
+that is necessary to ensure that the resulting daemon process is
+not a session leader.
+Instead, the resulting daemon
+.I is
+a session leader.
+.\" FIXME . https://sourceware.org/bugzilla/show_bug.cgi?id=19144
+.\" Tested using a program that uses daemon() and then opens an
+.\" otherwise unused console device (/dev/ttyN) that does not
+.\" have an associated getty process.
+On systems that follow System V semantics (e.g., Linux),
+this means that if the daemon opens a terminal that is not
+already a controlling terminal for another session,
+then that terminal will inadvertently become
+the controlling terminal for the daemon.
+.SH SEE ALSO
+.BR fork (2),
+.BR setsid (2),
+.BR daemon (7),
+.BR logrotate (8)
diff --git a/man/man3/daylight.3 b/man/man3/daylight.3
new file mode 100644
index 000000000..80907636c
--- /dev/null
+++ b/man/man3/daylight.3
@@ -0,0 +1 @@
+.so man3/tzset.3
diff --git a/man/man3/db.3 b/man/man3/db.3
new file mode 100644
index 000000000..03ede6636
--- /dev/null
+++ b/man/man3/db.3
@@ -0,0 +1 @@
+.so man3/dbopen.3
diff --git a/man/man3/dbopen.3 b/man/man3/dbopen.3
new file mode 100644
index 000000000..475f460a9
--- /dev/null
+++ b/man/man3/dbopen.3
@@ -0,0 +1,536 @@
+.\" Copyright (c) 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	@(#)dbopen.3	8.5 (Berkeley) 1/2/94
+.\"
+.TH dbopen 3 (date) "Linux man-pages (unreleased)"
+.UC 7
+.SH NAME
+dbopen \- database access methods
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <limits.h>
+.B #include <db.h>
+.B #include <fcntl.h>
+.P
+.BI "DB *dbopen(const char *" file ", int " flags ", int " mode \
+", DBTYPE " type ,
+.BI "           const void *" openinfo );
+.fi
+.SH DESCRIPTION
+.IR "Note well" :
+This page documents interfaces provided up until glibc 2.1.
+Since glibc 2.2, glibc no longer provides these interfaces.
+Probably, you are looking for the APIs provided by the
+.I libdb
+library instead.
+.P
+.BR dbopen ()
+is the library interface to database files.
+The supported file formats are btree, hashed, and UNIX file oriented.
+The btree format is a representation of a sorted, balanced tree structure.
+The hashed format is an extensible, dynamic hashing scheme.
+The flat-file format is a byte stream file with fixed or variable length
+records.
+The formats and file-format-specific information are described in detail
+in their respective manual pages
+.BR btree (3),
+.BR hash (3),
+and
+.BR recno (3).
+.P
+.BR dbopen ()
+opens
+.I file
+for reading and/or writing.
+Files never intended to be preserved on disk may be created by setting
+the
+.I file
+argument to NULL.
+.P
+The
+.I flags
+and
+.I mode
+arguments are as specified to the
+.BR open (2)
+routine, however, only the
+.BR O_CREAT ,
+.BR O_EXCL ,
+.BR O_EXLOCK ,
+.BR O_NONBLOCK ,
+.BR O_RDONLY ,
+.BR O_RDWR ,
+.BR O_SHLOCK ,
+and
+.B O_TRUNC
+flags are meaningful.
+(Note, opening a database file
+.B O_WRONLY
+is not possible.)
+.\"Three additional options may be specified by ORing
+.\"them into the
+.\".I flags
+.\"argument.
+.\".TP
+.\"DB_LOCK
+.\"Do the necessary locking in the database to support concurrent access.
+.\"If concurrent access isn't needed or the database is read-only this
+.\"flag should not be set, as it tends to have an associated performance
+.\"penalty.
+.\".TP
+.\"DB_SHMEM
+.\"Place the underlying memory pool used by the database in shared
+.\"memory.
+.\"Necessary for concurrent access.
+.\".TP
+.\"DB_TXN
+.\"Support transactions in the database.
+.\"The DB_LOCK and DB_SHMEM flags must be set as well.
+.P
+The
+.I type
+argument is of type
+.I DBTYPE
+(as defined in the
+.I <db.h>
+include file) and
+may be set to
+.BR DB_BTREE ,
+.BR DB_HASH ,
+or
+.BR DB_RECNO .
+.P
+The
+.I openinfo
+argument is a pointer to an access-method-specific structure described
+in the access method's manual page.
+If
+.I openinfo
+is NULL, each access method will use defaults appropriate for the system
+and the access method.
+.P
+.BR dbopen ()
+returns a pointer to a
+.I DB
+structure on success and NULL on error.
+The
+.I DB
+structure is defined in the
+.I <db.h>
+include file, and contains at
+least the following fields:
+.P
+.in +4n
+.EX
+typedef struct {
+    DBTYPE type;
+    int (*close)(const DB *db);
+    int (*del)(const DB *db, const DBT *key, unsigned int flags);
+    int (*fd)(const DB *db);
+    int (*get)(const DB *db, DBT *key, DBT *data,
+               unsigned int flags);
+    int (*put)(const DB *db, DBT *key, const DBT *data,
+               unsigned int flags);
+    int (*sync)(const DB *db, unsigned int flags);
+    int (*seq)(const DB *db, DBT *key, DBT *data,
+               unsigned int flags);
+} DB;
+.EE
+.in
+.P
+These elements describe a database type and a set of functions performing
+various actions.
+These functions take a pointer to a structure as returned by
+.BR dbopen (),
+and sometimes one or more pointers to key/data structures and a flag value.
+.TP
+.I type
+The type of the underlying access method (and file format).
+.TP
+.I close
+A pointer to a routine to flush any cached information to disk, free any
+allocated resources, and close the underlying file(s).
+Since key/data pairs may be cached in memory, failing to sync the file
+with a
+.I close
+or
+.I sync
+function may result in inconsistent or lost information.
+.I close
+routines return \-1 on error (setting
+.IR errno )
+and 0 on success.
+.TP
+.I del
+A pointer to a routine to remove key/data pairs from the database.
+.IP
+The argument
+.I flag
+may be set to the following value:
+.RS
+.TP
+.B R_CURSOR
+Delete the record referenced by the cursor.
+The cursor must have previously been initialized.
+.RE
+.IP
+.I delete
+routines return \-1 on error (setting
+.IR errno ),
+0 on success, and 1 if the specified
+.I key
+was not in the file.
+.TP
+.I fd
+A pointer to a routine which returns a file descriptor representative
+of the underlying database.
+A file descriptor referencing the same file will be returned to all
+processes which call
+.BR dbopen ()
+with the same
+.I file
+name.
+This file descriptor may be safely used as an argument to the
+.BR fcntl (2)
+and
+.BR flock (2)
+locking functions.
+The file descriptor is not necessarily associated with any of the
+underlying files used by the access method.
+No file descriptor is available for in memory databases.
+.I fd
+routines return \-1 on error (setting
+.IR errno ),
+and the file descriptor on success.
+.TP
+.I get
+A pointer to a routine which is the interface for keyed retrieval from
+the database.
+The address and length of the data associated with the specified
+.I key
+are returned in the structure referenced by
+.IR data .
+.I get
+routines return \-1 on error (setting
+.IR errno ),
+0 on success, and 1 if the
+.I key
+was not in the file.
+.TP
+.I put
+A pointer to a routine to store key/data pairs in the database.
+.IP
+The argument
+.I flag
+may be set to one of the following values:
+.RS
+.TP
+.B R_CURSOR
+Replace the key/data pair referenced by the cursor.
+The cursor must have previously been initialized.
+.TP
+.B R_IAFTER
+Append the data immediately after the data referenced by
+.IR key ,
+creating a new key/data pair.
+The record number of the appended key/data pair is returned in the
+.I key
+structure.
+(Applicable only to the
+.B DB_RECNO
+access method.)
+.TP
+.B R_IBEFORE
+Insert the data immediately before the data referenced by
+.IR key ,
+creating a new key/data pair.
+The record number of the inserted key/data pair is returned in the
+.I key
+structure.
+(Applicable only to the
+.B DB_RECNO
+access method.)
+.TP
+.B R_NOOVERWRITE
+Enter the new key/data pair only if the key does not previously exist.
+.TP
+.B R_SETCURSOR
+Store the key/data pair, setting or initializing the position of the
+cursor to reference it.
+(Applicable only to the
+.B DB_BTREE
+and
+.B DB_RECNO
+access methods.)
+.RE
+.IP
+.B R_SETCURSOR
+is available only for the
+.B DB_BTREE
+and
+.B DB_RECNO
+access
+methods because it implies that the keys have an inherent order
+which does not change.
+.IP
+.B R_IAFTER
+and
+.B R_IBEFORE
+are available only for the
+.B DB_RECNO
+access method because they each imply that the access method is able to
+create new keys.
+This is true only if the keys are ordered and independent, record numbers
+for example.
+.IP
+The default behavior of the
+.I put
+routines is to enter the new key/data pair, replacing any previously
+existing key.
+.IP
+.I put
+routines return \-1 on error (setting
+.IR errno ),
+0 on success, and 1 if the
+.B R_NOOVERWRITE
+.I flag
+was set and the key already exists in the file.
+.TP
+.I seq
+A pointer to a routine which is the interface for sequential
+retrieval from the database.
+The address and length of the key are returned in the structure
+referenced by
+.IR key ,
+and the address and length of the data are returned in the
+structure referenced
+by
+.IR data .
+.IP
+Sequential key/data pair retrieval may begin at any time, and the
+position of the "cursor" is not affected by calls to the
+.IR del ,
+.IR get ,
+.IR put ,
+or
+.I sync
+routines.
+Modifications to the database during a sequential scan will be reflected
+in the scan, that is,
+records inserted behind the cursor will not be returned
+while records inserted in front of the cursor will be returned.
+.IP
+The flag value
+.B must
+be set to one of the following values:
+.RS
+.TP
+.B R_CURSOR
+The data associated with the specified key is returned.
+This differs from the
+.I get
+routines in that it sets or initializes the cursor to the location of
+the key as well.
+(Note, for the
+.B DB_BTREE
+access method, the returned key is not necessarily an
+exact match for the specified key.
+The returned key is the smallest key greater than or equal to the specified
+key, permitting partial key matches and range searches.)
+.TP
+.B R_FIRST
+The first key/data pair of the database is returned, and the cursor
+is set or initialized to reference it.
+.TP
+.B R_LAST
+The last key/data pair of the database is returned, and the cursor
+is set or initialized to reference it.
+(Applicable only to the
+.B DB_BTREE
+and
+.B DB_RECNO
+access methods.)
+.TP
+.B R_NEXT
+Retrieve the key/data pair immediately after the cursor.
+If the cursor is not yet set, this is the same as the
+.B R_FIRST
+flag.
+.TP
+.B R_PREV
+Retrieve the key/data pair immediately before the cursor.
+If the cursor is not yet set, this is the same as the
+.B R_LAST
+flag.
+(Applicable only to the
+.B DB_BTREE
+and
+.B DB_RECNO
+access methods.)
+.RE
+.IP
+.B R_LAST
+and
+.B R_PREV
+are available only for the
+.B DB_BTREE
+and
+.B DB_RECNO
+access methods because they each imply that the keys have an inherent
+order which does not change.
+.IP
+.I seq
+routines return \-1 on error (setting
+.IR errno ),
+0 on success and 1 if there are no key/data pairs less than or greater
+than the specified or current key.
+If the
+.B DB_RECNO
+access method is being used, and if the database file
+is a character special file and no complete key/data pairs are currently
+available, the
+.I seq
+routines return 2.
+.TP
+.I sync
+A pointer to a routine to flush any cached information to disk.
+If the database is in memory only, the
+.I sync
+routine has no effect and will always succeed.
+.IP
+The flag value may be set to the following value:
+.RS
+.TP
+.B R_RECNOSYNC
+If the
+.B DB_RECNO
+access method is being used, this flag causes
+the sync routine to apply to the btree file which underlies the
+recno file, not the recno file itself.
+(See the
+.I bfname
+field of the
+.BR recno (3)
+manual page for more information.)
+.RE
+.IP
+.I sync
+routines return \-1 on error (setting
+.IR errno )
+and 0 on success.
+.SS Key/data pairs
+Access to all file types is based on key/data pairs.
+Both keys and data are represented by the following data structure:
+.P
+.in +4n
+.EX
+typedef struct {
+    void  *data;
+    size_t size;
+} DBT;
+.EE
+.in
+.P
+The elements of the
+.I DBT
+structure are defined as follows:
+.TP
+.I data
+A pointer to a byte string.
+.TP
+.I size
+The length of the byte string.
+.P
+Key and data byte strings may reference strings of essentially unlimited
+length although any two of them must fit into available memory at the same
+time.
+It should be noted that the access methods provide no guarantees about
+byte string alignment.
+.SH ERRORS
+The
+.BR dbopen ()
+routine may fail and set
+.I errno
+for any of the errors specified for the library routines
+.BR open (2)
+and
+.BR malloc (3)
+or the following:
+.TP
+.B EFTYPE
+A file is incorrectly formatted.
+.TP
+.B EINVAL
+A parameter has been specified (hash function, pad byte, etc.) that is
+incompatible with the current file specification or which is not
+meaningful for the function (for example, use of the cursor without
+prior initialization) or there is a mismatch between the version
+number of file and the software.
+.P
+The
+.I close
+routines may fail and set
+.I errno
+for any of the errors specified for the library routines
+.BR close (2),
+.BR read (2),
+.BR write (2),
+.BR free (3),
+or
+.BR fsync (2).
+.P
+The
+.IR del ,
+.IR get ,
+.IR put ,
+and
+.I seq
+routines may fail and set
+.I errno
+for any of the errors specified for the library routines
+.BR read (2),
+.BR write (2),
+.BR free (3),
+or
+.BR malloc (3).
+.P
+The
+.I fd
+routines will fail and set
+.I errno
+to
+.B ENOENT
+for in memory databases.
+.P
+The
+.I sync
+routines may fail and set
+.I errno
+for any of the errors specified for the library routine
+.BR fsync (2).
+.SH BUGS
+The typedef
+.I DBT
+is a mnemonic for "data base thang", and was used
+because no one could think of a reasonable name that wasn't already used.
+.P
+The file descriptor interface is a kludge and will be deleted in a
+future version of the interface.
+.P
+None of the access methods provide any form of concurrent access,
+locking, or transactions.
+.SH SEE ALSO
+.BR btree (3),
+.BR hash (3),
+.BR mpool (3),
+.BR recno (3)
+.P
+.IR "LIBTP: Portable, Modular Transactions for UNIX" ,
+Margo Seltzer, Michael Olson, USENIX proceedings, Winter 1992.
diff --git a/man/man3/des_crypt.3 b/man/man3/des_crypt.3
new file mode 100644
index 000000000..ca89b04bb
--- /dev/null
+++ b/man/man3/des_crypt.3
@@ -0,0 +1,164 @@
+'\" t
+.\" @(#)des_crypt.3	2.1 88/08/11 4.0 RPCSRC; from 1.16 88/03/02 SMI;
+.\"
+.\" Taken from libc4 sources, which say:
+.\" Copyright (C) 1993 Eric Young - can be distributed under GPL.
+.\"
+.\" However, the above header line suggests that this file in fact is
+.\" Copyright Sun Microsystems, Inc (and is provided for unrestricted use,
+.\" see other Sun RPC sources).
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH des_crypt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+des_crypt, ecb_crypt, cbc_crypt, des_setparity, DES_FAILED \- fast
+DES encryption
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.\" Sun version
+.\" .B #include <des_crypt.h>
+.B #include <rpc/des_crypt.h>
+.P
+.BI "[[deprecated]] int ecb_crypt(char *" key ", char " data [. datalen ],
+.BI "                             unsigned int " datalen ", \
+unsigned int " mode );
+.BI "[[deprecated]] int cbc_crypt(char *" key ", char " data [. datalen ],
+.BI "                             unsigned int " datalen ", \
+unsigned int " mode ,
+.BI "                             char *" ivec );
+.P
+.BI "[[deprecated]] void des_setparity(char *" key );
+.P
+.BI "[[deprecated]] int DES_FAILED(int " status );
+.fi
+.SH DESCRIPTION
+.BR ecb_crypt ()
+and
+.BR cbc_crypt ()
+implement the
+NBS
+DES
+(Data Encryption Standard).
+These routines are faster and more general purpose than
+.BR crypt (3).
+They also are able to utilize
+DES
+hardware if it is available.
+.BR ecb_crypt ()
+encrypts in
+ECB
+(Electronic Code Book)
+mode, which encrypts blocks of data independently.
+.BR cbc_crypt ()
+encrypts in
+CBC
+(Cipher Block Chaining)
+mode, which chains together
+successive blocks.
+CBC
+mode protects against insertions, deletions, and
+substitutions of blocks.
+Also, regularities in the clear text will
+not appear in the cipher text.
+.P
+Here is how to use these routines.
+The first argument,
+.IR key ,
+is the 8-byte encryption key with parity.
+To set the key's parity, which for
+DES
+is in the low bit of each byte, use
+.BR des_setparity ().
+The second argument,
+.IR data ,
+contains the data to be encrypted or decrypted.
+The
+third argument,
+.IR datalen ,
+is the length in bytes of
+.IR data ,
+which must be a multiple of 8.
+The fourth argument,
+.IR mode ,
+is formed by ORing together some things.
+For the encryption direction OR in either
+.B DES_ENCRYPT
+or
+.BR DES_DECRYPT .
+For software versus hardware
+encryption, OR in either
+.B DES_HW
+or
+.BR DES_SW .
+If
+.B DES_HW
+is specified, and there is no hardware, then the encryption is performed
+in software and the routine returns
+.BR DESERR_NOHWDEVICE .
+For
+.BR cbc_crypt (),
+the argument
+.I ivec
+is the 8-byte initialization
+vector for the chaining.
+It is updated to the next initialization
+vector upon return.
+.SH RETURN VALUE
+.TP
+.B DESERR_NONE
+No error.
+.TP
+.B DESERR_NOHWDEVICE
+Encryption succeeded, but done in software instead of the requested hardware.
+.TP
+.B DESERR_HWERROR
+An error occurred in the hardware or driver.
+.TP
+.B DESERR_BADPARAM
+Bad argument to routine.
+.P
+Given a result status
+.IR stat ,
+the macro
+.\" .BR DES_FAILED\c
+.\" .BR ( stat )
+.BI DES_FAILED( stat )
+is false only for the first two statuses.
+.\" So far the Sun page
+.\" Some additions - aeb
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ecb_crypt (),
+.BR cbc_crypt (),
+.BR des_setparity ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD.
+glibc 2.1.
+Removed in glibc 2.28.
+.P
+Because they employ the DES block cipher,
+which is no longer considered secure,
+these functions were removed.
+Applications should switch to a modern cryptography library, such as
+.BR libgcrypt .
+.SH SEE ALSO
+.BR des (1),
+.BR crypt (3),
+.BR xcrypt (3)
diff --git a/man/man3/des_setparity.3 b/man/man3/des_setparity.3
new file mode 100644
index 000000000..853c9cbdf
--- /dev/null
+++ b/man/man3/des_setparity.3
@@ -0,0 +1 @@
+.so man3/des_crypt.3
diff --git a/man/man3/difftime.3 b/man/man3/difftime.3
new file mode 100644
index 000000000..895a31c6d
--- /dev/null
+++ b/man/man3/difftime.3
@@ -0,0 +1,60 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:48:17 1993 by Rik Faith (faith@cs.unc.edu)
+.TH difftime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+difftime \- calculate time difference
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "double difftime(time_t " time1 ", time_t " time0 );
+.fi
+.SH DESCRIPTION
+The
+.BR difftime ()
+function returns the number of seconds elapsed
+between time \fItime1\fP and time \fItime0\fP, represented as a
+.IR double .
+Each time is a count of seconds.
+.P
+.I difftime(b,\~a)
+acts like
+.I (b\-a)
+except that the result does not overflow and is rounded to
+.IR double .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR difftime ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR date (1),
+.BR gettimeofday (2),
+.BR time (2),
+.BR ctime (3),
+.BR gmtime (3),
+.BR localtime (3)
diff --git a/man/man3/dirfd.3 b/man/man3/dirfd.3
new file mode 100644
index 000000000..54ec28165
--- /dev/null
+++ b/man/man3/dirfd.3
@@ -0,0 +1,93 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH dirfd 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dirfd \- get directory stream file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <dirent.h>
+.P
+.BI "int dirfd(DIR *" dirp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR dirfd ():
+.nf
+    /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The function
+.BR dirfd ()
+returns the file descriptor associated with the directory stream
+.IR dirp .
+.P
+This file descriptor is the one used internally by the directory stream.
+As a result, it is useful only for functions which do not depend on
+or alter the file position, such as
+.BR fstat (2)
+and
+.BR fchdir (2).
+It will be automatically closed when
+.BR closedir (3)
+is called.
+.SH RETURN VALUE
+On success,
+.BR dirfd ()
+returns a file descriptor (a nonnegative integer).
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+POSIX.1-2008 specifies two errors,
+neither of which is returned by the current
+.\" glibc 2.8
+implementation.
+.TP
+.B EINVAL
+.I dirp
+does not refer to a valid directory stream.
+.TP
+.B ENOTSUP
+The implementation does not support the association of a file
+descriptor with a directory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dirfd ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+4.3BSD-Reno (not in 4.2BSD).
+.\" It is present in libc5 (since 5.1.2) and in glibc 2.
+.SH SEE ALSO
+.BR open (2),
+.BR openat (2),
+.BR closedir (3),
+.BR opendir (3),
+.BR readdir (3),
+.BR rewinddir (3),
+.BR scandir (3),
+.BR seekdir (3),
+.BR telldir (3)
diff --git a/man/man3/dirname.3 b/man/man3/dirname.3
new file mode 100644
index 000000000..9099c1ad7
--- /dev/null
+++ b/man/man3/dirname.3
@@ -0,0 +1 @@
+.so man3/basename.3
diff --git a/man/man3/div.3 b/man/man3/div.3
new file mode 100644
index 000000000..cdcdecbf9
--- /dev/null
+++ b/man/man3/div.3
@@ -0,0 +1,105 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified 1993-03-29, David Metcalfe
+.\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-08-10, 2003-11-01 Walter Harms, aeb
+.\"
+.TH div 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+div, ldiv, lldiv, imaxdiv \- compute quotient and remainder of
+an integer division
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "div_t div(int " numerator ", int " denominator );
+.BI "ldiv_t ldiv(long " numerator ", long " denominator );
+.BI "lldiv_t lldiv(long long " numerator ", long long " denominator );
+.P
+.B #include <inttypes.h>
+.P
+.BI "imaxdiv_t imaxdiv(intmax_t " numerator ", intmax_t " denominator );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR lldiv ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR div ()
+function computes the value
+\fInumerator\fP/\fIdenominator\fP and
+returns the quotient and remainder in a structure
+named \fIdiv_t\fP that contains
+two integer members (in unspecified order) named \fIquot\fP and \fIrem\fP.
+The quotient is rounded toward zero.
+The result satisfies \fIquot\fP*\fIdenominator\fP+\fIrem\fP = \fInumerator\fP.
+.P
+The
+.BR ldiv (),
+.BR lldiv (),
+and
+.BR imaxdiv ()
+functions do the same,
+dividing numbers of the indicated type and
+returning the result in a structure
+of the indicated name, in all cases with fields \fIquot\fP and \fIrem\fP
+of the same type as the function arguments.
+.SH RETURN VALUE
+The \fIdiv_t\fP (etc.) structure.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR div (),
+.BR ldiv (),
+.BR lldiv (),
+.BR imaxdiv ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, C99, SVr4, 4.3BSD.
+.P
+.BR lldiv ()
+and
+.BR imaxdiv ()
+were added in C99.
+.SH EXAMPLES
+After
+.P
+.in +4n
+.EX
+div_t q = div(\-5, 3);
+.EE
+.in
+.P
+the values \fIq.quot\fP and \fIq.rem\fP are \-1 and \-2, respectively.
+.SH SEE ALSO
+.BR abs (3),
+.BR remainder (3)
diff --git a/man/man3/dl_iterate_phdr.3 b/man/man3/dl_iterate_phdr.3
new file mode 100644
index 000000000..0a8beb3ae
--- /dev/null
+++ b/man/man3/dl_iterate_phdr.3
@@ -0,0 +1,345 @@
+'\" t
+.\" Copyright (c) 2003, 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH dl_iterate_phdr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dl_iterate_phdr \- walk through list of shared objects
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <link.h>
+.P
+.B int dl_iterate_phdr(
+.BI "          int (*" callback ")(struct dl_phdr_info *" info ,
+.BI "                          size_t " size ", void *" data ),
+.BI "          void *" data );
+.fi
+.SH DESCRIPTION
+The
+.BR dl_iterate_phdr ()
+function allows an application to inquire at run time to find
+out which shared objects it has loaded,
+and the order in which they were loaded.
+.P
+The
+.BR dl_iterate_phdr ()
+function walks through the list of an
+application's shared objects and calls the function
+.I callback
+once for each object,
+until either all shared objects have been processed or
+.I callback
+returns a nonzero value.
+.P
+Each call to
+.I callback
+receives three arguments:
+.IR info ,
+which is a pointer to a structure containing information
+about the shared object;
+.IR size ,
+which is the size of the structure pointed to by
+.IR info ;
+and
+.IR data ,
+which is a copy of whatever value was passed by the calling
+program as the second argument (also named
+.IR data )
+in the call to
+.BR dl_iterate_phdr ().
+.P
+The
+.I info
+argument is a structure of the following type:
+.P
+.in +4n
+.EX
+struct dl_phdr_info {
+    ElfW(Addr)        dlpi_addr;  /* Base address of object */
+    const char       *dlpi_name;  /* (Null\-terminated) name of
+                                     object */
+    const ElfW(Phdr) *dlpi_phdr;  /* Pointer to array of
+                                     ELF program headers
+                                     for this object */
+    ElfW(Half)        dlpi_phnum; /* # of items in \fIdlpi_phdr\fP */
+\&
+    /* The following fields were added in glibc 2.4, after the first
+       version of this structure was available.  Check the \fIsize\fP
+       argument passed to the dl_iterate_phdr callback to determine
+       whether or not each later member is available.  */
+\&
+    unsigned long long dlpi_adds;
+                    /* Incremented when a new object may
+                       have been added */
+    unsigned long long dlpi_subs;
+                    /* Incremented when an object may
+                       have been removed */
+    size_t dlpi_tls_modid;
+                    /* If there is a PT_TLS segment, its module
+                       ID as used in TLS relocations, else zero */
+    void  *dlpi_tls_data;
+                    /* The address of the calling thread\[aq]s instance
+                       of this module\[aq]s PT_TLS segment, if it has
+                       one and it has been allocated in the calling
+                       thread, otherwise a null pointer */
+};
+.EE
+.in
+.P
+(The
+.IR ElfW ()
+macro definition turns its argument into the name of an ELF data
+type suitable for the hardware architecture.
+For example, on a 32-bit platform,
+.I ElfW(Addr)
+yields the data type name
+.IR Elf32_Addr .
+Further information on these types can be found in the
+.IR <elf.h> " and " <link.h>
+header files.)
+.P
+The
+.I dlpi_addr
+field indicates the base address of the shared object
+(i.e., the difference between the virtual memory address of
+the shared object and the offset of that object in the file
+from which it was loaded).
+The
+.I dlpi_name
+field is a null-terminated string giving the pathname
+from which the shared object was loaded.
+.P
+To understand the meaning of the
+.I dlpi_phdr
+and
+.I dlpi_phnum
+fields, we need to be aware that an ELF shared object consists
+of a number of segments, each of which has a corresponding
+program header describing the segment.
+The
+.I dlpi_phdr
+field is a pointer to an array of the program headers for this
+shared object.
+The
+.I dlpi_phnum
+field indicates the size of this array.
+.P
+These program headers are structures of the following form:
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf32_Word  p_type;    /* Segment type */
+    Elf32_Off   p_offset;  /* Segment file offset */
+    Elf32_Addr  p_vaddr;   /* Segment virtual address */
+    Elf32_Addr  p_paddr;   /* Segment physical address */
+    Elf32_Word  p_filesz;  /* Segment size in file */
+    Elf32_Word  p_memsz;   /* Segment size in memory */
+    Elf32_Word  p_flags;   /* Segment flags */
+    Elf32_Word  p_align;   /* Segment alignment */
+} Elf32_Phdr;
+.EE
+.in
+.P
+Note that we can calculate the location of a particular program header,
+.IR x ,
+in virtual memory using the formula:
+.P
+.in +4n
+.EX
+addr == info\->dlpi_addr + info\->dlpi_phdr[x].p_vaddr;
+.EE
+.in
+.P
+Possible values for
+.I p_type
+include the following (see
+.I <elf.h>
+for further details):
+.P
+.in +4n
+.EX
+#define PT_LOAD         1    /* Loadable program segment */
+#define PT_DYNAMIC      2    /* Dynamic linking information */
+#define PT_INTERP       3    /* Program interpreter */
+#define PT_NOTE         4    /* Auxiliary information */
+#define PT_SHLIB        5    /* Reserved */
+#define PT_PHDR         6    /* Entry for header table itself */
+#define PT_TLS          7    /* Thread\-local storage segment */
+#define PT_GNU_EH_FRAME 0x6474e550 /* GCC .eh_frame_hdr segment */
+#define PT_GNU_STACK  0x6474e551 /* Indicates stack executability */
+.\" For PT_GNU_STACK, see http://www.airs.com/blog/archives/518
+#define PT_GNU_RELRO  0x6474e552 /* Read\-only after relocation */
+.EE
+.in
+.SH RETURN VALUE
+The
+.BR dl_iterate_phdr ()
+function returns whatever value was returned by the last call to
+.IR callback .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dl_iterate_phdr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Various other systems provide a version of this function,
+although details of the returned
+.I dl_phdr_info
+structure differ.
+On the BSDs and Solaris, the structure includes the fields
+.IR dlpi_addr ,
+.IR dlpi_name ,
+.IR dlpi_phdr ,
+and
+.I dlpi_phnum
+in addition to other implementation-specific fields.
+.P
+Future versions of the C library may add further fields to the
+.I dl_phdr_info
+structure; in that event, the
+.I size
+argument provides a mechanism for the callback function to discover
+whether it is running on a system with added fields.
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.2.4.
+.SH NOTES
+The first object visited by
+.I callback
+is the main program.
+For the main program, the
+.I dlpi_name
+field will be an empty string.
+.SH EXAMPLES
+The following program displays a list of pathnames of the
+shared objects it has loaded.
+For each shared object, the program lists some information
+(virtual address, size, flags, and type)
+for each of the objects ELF segments.
+.P
+The following shell session demonstrates the output
+produced by the program on an x86-64 system.
+The first shared object for which output is displayed
+(where the name is an empty string)
+is the main program.
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+Name: "" (9 segments)
+     0: [      0x400040; memsz:    1f8] flags: 0x5; PT_PHDR
+     1: [      0x400238; memsz:     1c] flags: 0x4; PT_INTERP
+     2: [      0x400000; memsz:    ac4] flags: 0x5; PT_LOAD
+     3: [      0x600e10; memsz:    240] flags: 0x6; PT_LOAD
+     4: [      0x600e28; memsz:    1d0] flags: 0x6; PT_DYNAMIC
+     5: [      0x400254; memsz:     44] flags: 0x4; PT_NOTE
+     6: [      0x400970; memsz:     3c] flags: 0x4; PT_GNU_EH_FRAME
+     7: [         (nil); memsz:      0] flags: 0x6; PT_GNU_STACK
+     8: [      0x600e10; memsz:    1f0] flags: 0x4; PT_GNU_RELRO
+Name: "linux\-vdso.so.1" (4 segments)
+     0: [0x7ffc6edd1000; memsz:    e89] flags: 0x5; PT_LOAD
+     1: [0x7ffc6edd1360; memsz:    110] flags: 0x4; PT_DYNAMIC
+     2: [0x7ffc6edd17b0; memsz:     3c] flags: 0x4; PT_NOTE
+     3: [0x7ffc6edd17ec; memsz:     3c] flags: 0x4; PT_GNU_EH_FRAME
+Name: "/lib64/libc.so.6" (10 segments)
+     0: [0x7f55712ce040; memsz:    230] flags: 0x5; PT_PHDR
+     1: [0x7f557145b980; memsz:     1c] flags: 0x4; PT_INTERP
+     2: [0x7f55712ce000; memsz: 1b6a5c] flags: 0x5; PT_LOAD
+     3: [0x7f55716857a0; memsz:   9240] flags: 0x6; PT_LOAD
+     4: [0x7f5571688b80; memsz:    1f0] flags: 0x6; PT_DYNAMIC
+     5: [0x7f55712ce270; memsz:     44] flags: 0x4; PT_NOTE
+     6: [0x7f55716857a0; memsz:     78] flags: 0x4; PT_TLS
+     7: [0x7f557145b99c; memsz:   544c] flags: 0x4; PT_GNU_EH_FRAME
+     8: [0x7f55712ce000; memsz:      0] flags: 0x6; PT_GNU_STACK
+     9: [0x7f55716857a0; memsz:   3860] flags: 0x4; PT_GNU_RELRO
+Name: "/lib64/ld\-linux\-x86\-64.so.2" (7 segments)
+     0: [0x7f557168f000; memsz:  20828] flags: 0x5; PT_LOAD
+     1: [0x7f55718afba0; memsz:   15a8] flags: 0x6; PT_LOAD
+     2: [0x7f55718afe10; memsz:    190] flags: 0x6; PT_DYNAMIC
+     3: [0x7f557168f1c8; memsz:     24] flags: 0x4; PT_NOTE
+     4: [0x7f55716acec4; memsz:    604] flags: 0x4; PT_GNU_EH_FRAME
+     5: [0x7f557168f000; memsz:      0] flags: 0x6; PT_GNU_STACK
+     6: [0x7f55718afba0; memsz:    460] flags: 0x4; PT_GNU_RELRO
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (dl_iterate_phdr.c)
+.EX
+#define _GNU_SOURCE
+#include <link.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+static int
+callback(struct dl_phdr_info *info, size_t size, void *data)
+{
+    char *type;
+    int p_type;
+\&
+    printf("Name: \e"%s\e" (%d segments)\en", info\->dlpi_name,
+           info\->dlpi_phnum);
+\&
+    for (size_t j = 0; j < info\->dlpi_phnum; j++) {
+        p_type = info\->dlpi_phdr[j].p_type;
+        type = (p_type == PT_LOAD) ? "PT_LOAD" :
+               (p_type == PT_DYNAMIC) ? "PT_DYNAMIC" :
+               (p_type == PT_INTERP) ? "PT_INTERP" :
+               (p_type == PT_NOTE) ? "PT_NOTE" :
+               (p_type == PT_INTERP) ? "PT_INTERP" :
+               (p_type == PT_PHDR) ? "PT_PHDR" :
+               (p_type == PT_TLS) ? "PT_TLS" :
+               (p_type == PT_GNU_EH_FRAME) ? "PT_GNU_EH_FRAME" :
+               (p_type == PT_GNU_STACK) ? "PT_GNU_STACK" :
+               (p_type == PT_GNU_RELRO) ? "PT_GNU_RELRO" : NULL;
+\&
+        printf("    %2zu: [%14p; memsz:%7jx] flags: %#jx; ", j,
+               (void *) (info\->dlpi_addr + info\->dlpi_phdr[j].p_vaddr),
+               (uintmax_t) info\->dlpi_phdr[j].p_memsz,
+               (uintmax_t) info\->dlpi_phdr[j].p_flags);
+        if (type != NULL)
+            printf("%s\en", type);
+        else
+            printf("[other (%#x)]\en", p_type);
+    }
+\&
+    return 0;
+}
+\&
+int
+main(void)
+{
+    dl_iterate_phdr(callback, NULL);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ldd (1),
+.BR objdump (1),
+.BR readelf (1),
+.BR dladdr (3),
+.BR dlopen (3),
+.BR elf (5),
+.BR ld.so (8)
+.P
+.IR "Executable and Linking Format Specification" ,
+available at various locations online.
diff --git a/man/man3/dladdr.3 b/man/man3/dladdr.3
new file mode 100644
index 000000000..f52437df8
--- /dev/null
+++ b/man/man3/dladdr.3
@@ -0,0 +1,275 @@
+'\" t
+.\" Copyright (C) 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2008 Petr Baudis <pasky@suse.cz> (dladdr caveat)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH dladdr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dladdr, dladdr1 \- translate address to symbolic information
+.SH LIBRARY
+Dynamic linking library
+.RI ( libdl ", " \-ldl )
+.SH SYNOPSIS
+.nf
+.B #define _GNU_SOURCE
+.B #include <dlfcn.h>
+.P
+.BI "int dladdr(const void *" addr ", Dl_info *" info );
+.BI "int dladdr1(const void *" addr ", Dl_info *" info ", void **" extra_info ,
+.BI "            int " flags );
+.fi
+.SH DESCRIPTION
+The function
+.BR dladdr ()
+determines whether the address specified in
+.I addr
+is located in one of the shared objects loaded by the calling application.
+If it is, then
+.BR dladdr ()
+returns information about the shared object and symbol that overlaps
+.IR addr .
+This information is returned in a
+.I Dl_info
+structure:
+.P
+.in +4n
+.EX
+typedef struct {
+    const char *dli_fname;  /* Pathname of shared object that
+                               contains address */
+    void       *dli_fbase;  /* Base address at which shared
+                               object is loaded */
+    const char *dli_sname;  /* Name of symbol whose definition
+                               overlaps \fIaddr\fP */
+    void       *dli_saddr;  /* Exact address of symbol named
+                               in \fIdli_sname\fP */
+} Dl_info;
+.EE
+.in
+.P
+If no symbol matching
+.I addr
+could be found, then
+.I dli_sname
+and
+.I dli_saddr
+are set to NULL.
+.P
+The function
+.BR dladdr1 ()
+is like
+.BR dladdr (),
+but returns additional information via the argument
+.IR extra_info .
+The information returned depends on the value specified in
+.IR flags ,
+which can have one of the following values:
+.TP
+.B RTLD_DL_LINKMAP
+Obtain a pointer to the link map for the matched file.
+The
+.I extra_info
+argument points to a pointer to a
+.I link_map
+structure (i.e.,
+.IR "struct link_map\~**" ),
+defined in
+.I <link.h>
+as:
+.IP
+.in +4n
+.EX
+struct link_map {
+    ElfW(Addr) l_addr;  /* Difference between the
+                           address in the ELF file and
+                           the address in memory */
+    char      *l_name;  /* Absolute pathname where
+                           object was found */
+    ElfW(Dyn) *l_ld;    /* Dynamic section of the
+                           shared object */
+    struct link_map *l_next, *l_prev;
+                        /* Chain of loaded objects */
+\&
+    /* Plus additional fields private to the
+       implementation */
+};
+.EE
+.in
+.TP
+.B RTLD_DL_SYMENT
+Obtain a pointer to the ELF symbol table entry of the matching symbol.
+The
+.I extra_info
+argument is a pointer to a symbol pointer:
+.IR "const ElfW(Sym) **" .
+The
+.IR ElfW ()
+macro definition turns its argument into the name of an ELF data
+type suitable for the hardware architecture.
+For example, on a 64-bit platform,
+.I ElfW(Sym)
+yields the data type name
+.IR Elf64_Sym ,
+which is defined in
+.I <elf.h>
+as:
+.IP
+.in +4n
+.EX
+typedef struct  {
+    Elf64_Word    st_name;     /* Symbol name */
+    unsigned char st_info;     /* Symbol type and binding */
+    unsigned char st_other;    /* Symbol visibility */
+    Elf64_Section st_shndx;    /* Section index */
+    Elf64_Addr    st_value;    /* Symbol value */
+    Elf64_Xword   st_size;     /* Symbol size */
+} Elf64_Sym;
+.EE
+.in
+.IP
+The
+.I st_name
+field is an index into the string table.
+.IP
+The
+.I st_info
+field encodes the symbol's type and binding.
+The type can be extracted using the macro
+.B ELF64_ST_TYPE(st_info)
+(or
+.B ELF32_ST_TYPE()
+on 32-bit platforms), which yields one of the following values:
+.in +4n
+.TS
+lb lb
+lb l.
+Value	Description
+STT_NOTYPE	Symbol type is unspecified
+STT_OBJECT	Symbol is a data object
+STT_FUNC	Symbol is a code object
+STT_SECTION	Symbol associated with a section
+STT_FILE	Symbol's name is filename
+STT_COMMON	Symbol is a common data object
+STT_TLS	Symbol is thread-local data object
+STT_GNU_IFUNC	Symbol is indirect code object
+.TE
+.in
+.IP
+The symbol binding can be extracted from the
+.I st_info
+field using the macro
+.B ELF64_ST_BIND(st_info)
+(or
+.B ELF32_ST_BIND()
+on 32-bit platforms), which yields one of the following values:
+.in +4n
+.TS
+lb lb
+lb l.
+Value	Description
+STB_LOCAL	Local symbol
+STB_GLOBAL	Global symbol
+STB_WEAK	Weak symbol
+STB_GNU_UNIQUE	Unique symbol
+.TE
+.in
+.IP
+The
+.I st_other
+field contains the symbol's visibility, which can be extracted using the macro
+.B ELF64_ST_VISIBILITY(st_info)
+(or
+.B ELF32_ST_VISIBILITY()
+on 32-bit platforms), which yields one of the following values:
+.in +4n
+.TS
+lb lb
+lb l.
+Value	Description
+STV_DEFAULT	Default symbol visibility rules
+STV_INTERNAL	Processor-specific hidden class
+STV_HIDDEN	Symbol unavailable in other modules
+STV_PROTECTED	Not preemptible, not exported
+.TE
+.in
+.SH RETURN VALUE
+On success, these functions return a nonzero value.
+If the address specified in
+.I addr
+could be matched to a shared object,
+but not to a symbol in the shared object, then the
+.I info\->dli_sname
+and
+.I info\->dli_saddr
+fields are set to NULL.
+.P
+If the address specified in
+.I addr
+could not be matched to a shared object, then these functions return 0.
+In this case, an error message is
+.I not
+.\" According to the FreeBSD man page, dladdr1() does signal an
+.\" error via dlerror() for this case.
+available via
+.BR dlerror (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dladdr (),
+.BR dladdr1 ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+.TP
+.BR dladdr ()
+glibc 2.0.
+.TP
+.BR dladdr1 ()
+glibc 2.3.3.
+.P
+Solaris.
+.SH BUGS
+Sometimes, the function pointers you pass to
+.BR dladdr ()
+may surprise you.
+On some architectures (notably i386 and x86-64),
+.I dli_fname
+and
+.I dli_fbase
+may end up pointing back at the object from which you called
+.BR dladdr (),
+even if the function used as an argument should come from
+a dynamically linked library.
+.P
+The problem is that the function pointer will still be resolved
+at compile time, but merely point to the
+.I plt
+(Procedure Linkage Table)
+section of the original object (which dispatches the call after
+asking the dynamic linker to resolve the symbol).
+To work around this,
+you can try to compile the code to be position-independent:
+then, the compiler cannot prepare the pointer
+at compile time any more and
+.BR gcc (1)
+will generate code that just loads the final symbol address from the
+.I got
+(Global Offset Table) at run time before passing it to
+.BR dladdr ().
+.SH SEE ALSO
+.BR dl_iterate_phdr (3),
+.BR dlinfo (3),
+.BR dlopen (3),
+.BR dlsym (3),
+.BR ld.so (8)
diff --git a/man/man3/dladdr1.3 b/man/man3/dladdr1.3
new file mode 100644
index 000000000..43979e52a
--- /dev/null
+++ b/man/man3/dladdr1.3
@@ -0,0 +1 @@
+.so man3/dladdr.3
diff --git a/man/man3/dlclose.3 b/man/man3/dlclose.3
new file mode 100644
index 000000000..15d096806
--- /dev/null
+++ b/man/man3/dlclose.3
@@ -0,0 +1 @@
+.so man3/dlopen.3
diff --git a/man/man3/dlerror.3 b/man/man3/dlerror.3
new file mode 100644
index 000000000..a779c12db
--- /dev/null
+++ b/man/man3/dlerror.3
@@ -0,0 +1,78 @@
+'\" t
+.\" Copyright 1995 Yggdrasil Computing, Incorporated.
+.\" and Copyright 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH dlerror 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dlerror \- obtain error diagnostic for functions in the dlopen API
+.SH LIBRARY
+Dynamic linking library
+.RI ( libdl ", " \-ldl )
+.SH SYNOPSIS
+.nf
+.B #include <dlfcn.h>
+.P
+.B "char *dlerror(void);"
+.fi
+.SH DESCRIPTION
+The
+.BR dlerror ()
+function returns a human-readable,
+null-terminated string describing the most recent error
+that occurred from a call to one of the functions in the dlopen API
+since the last call to
+.BR dlerror ().
+The returned string does
+.I not
+include a trailing newline.
+.P
+.BR dlerror ()
+returns NULL if no errors have occurred since initialization or since
+it was last called.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dlerror ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.0.
+POSIX.1-2001.
+.P
+SunOS.
+.SH NOTES
+The message returned by
+.BR dlerror ()
+may reside in a statically allocated buffer that is
+overwritten by subsequent
+.BR dlerror ()
+calls.
+.\" .P
+.\" The string returned by
+.\" .BR dlerror ()
+.\" should not be modified.
+.\" Some systems give the prototype as
+.\" .sp
+.\" .in +5
+.\" .B "const char *dlerror(void);"
+.\" .in
+.SH EXAMPLES
+See
+.BR dlopen (3).
+.SH SEE ALSO
+.BR dladdr (3),
+.BR dlinfo (3),
+.BR dlopen (3),
+.BR dlsym (3)
diff --git a/man/man3/dlinfo.3 b/man/man3/dlinfo.3
new file mode 100644
index 000000000..c3a5662ca
--- /dev/null
+++ b/man/man3/dlinfo.3
@@ -0,0 +1,317 @@
+'\" t
+.\" Copyright (C) 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH dlinfo 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dlinfo \- obtain information about a dynamically loaded object
+.SH LIBRARY
+Dynamic linking library
+.RI ( libdl ", " \-ldl )
+.SH SYNOPSIS
+.nf
+.B #define _GNU_SOURCE
+.B #include <link.h>
+.B #include <dlfcn.h>
+.P
+.BR "int dlinfo(void *restrict " handle ", int " request \
+", void *restrict " info );
+.fi
+.SH DESCRIPTION
+The
+.BR dlinfo ()
+function obtains information about the dynamically loaded object
+referred to by
+.I handle
+(typically obtained by an earlier call to
+.BR dlopen (3)
+or
+.BR dlmopen (3)).
+The
+.I request
+argument specifies which information is to be returned.
+The
+.I info
+argument is a pointer to a buffer used to store information
+returned by the call; the type of this argument depends on
+.IR request .
+.P
+The following values are supported for
+.I request
+(with the corresponding type for
+.I info
+shown in parentheses):
+.TP
+.BR RTLD_DI_LMID " (\fILmid_t *\fP)"
+Obtain the ID of the link-map list (namespace) in which
+.I handle
+is loaded.
+.TP
+.BR RTLD_DI_LINKMAP " (\fIstruct link_map **\fP)"
+Obtain a pointer to the
+.I link_map
+structure corresponding to
+.IR handle .
+The
+.I info
+argument points to a pointer to a
+.I link_map
+structure, defined in
+.I <link.h>
+as:
+.IP
+.in +4n
+.EX
+struct link_map {
+    ElfW(Addr) l_addr;  /* Difference between the
+                           address in the ELF file and
+                           the address in memory */
+    char      *l_name;  /* Absolute pathname where
+                           object was found */
+    ElfW(Dyn) *l_ld;    /* Dynamic section of the
+                           shared object */
+    struct link_map *l_next, *l_prev;
+                        /* Chain of loaded objects */
+\&
+    /* Plus additional fields private to the
+       implementation */
+};
+.EE
+.in
+.TP
+.BR RTLD_DI_ORIGIN " (\fIchar *\fP)"
+Copy the pathname of the origin of the shared object corresponding to
+.I handle
+to the location pointed to by
+.IR info .
+.TP
+.BR RTLD_DI_SERINFO " (\fIDl_serinfo *\fP)"
+Obtain the library search paths for the shared object referred to by
+.IR handle .
+The
+.I info
+argument is a pointer to a
+.I Dl_serinfo
+that contains the search paths.
+Because the number of search paths may vary,
+the size of the structure pointed to by
+.I info
+can vary.
+The
+.B RTLD_DI_SERINFOSIZE
+request described below allows applications to size the buffer suitably.
+The caller must perform the following steps:
+.RS
+.IP (1) 5
+Use a
+.B RTLD_DI_SERINFOSIZE
+request to populate a
+.I Dl_serinfo
+structure with the size
+.RI ( dls_size )
+of the structure needed for the subsequent
+.B RTLD_DI_SERINFO
+request.
+.IP (2)
+Allocate a
+.I Dl_serinfo
+buffer of the correct size
+.RI ( dls_size ).
+.IP (3)
+Use a further
+.B RTLD_DI_SERINFOSIZE
+request to populate the
+.I dls_size
+and
+.I dls_cnt
+fields of the buffer allocated in the previous step.
+.IP (4)
+Use a
+.B RTLD_DI_SERINFO
+to obtain the library search paths.
+.RE
+.IP
+The
+.I Dl_serinfo
+structure is defined as follows:
+.IP
+.in +4n
+.EX
+typedef struct {
+    size_t dls_size;           /* Size in bytes of
+                                  the whole buffer */
+    unsigned int dls_cnt;      /* Number of elements
+                                  in \[aq]dls_serpath\[aq] */
+    Dl_serpath dls_serpath[1]; /* Actually longer,
+                                  \[aq]dls_cnt\[aq] elements */
+} Dl_serinfo;
+.EE
+.in
+.IP
+Each of the
+.I dls_serpath
+elements in the above structure is a structure of the following form:
+.IP
+.in +4n
+.EX
+typedef struct {
+    char *dls_name;            /* Name of library search
+                                  path directory */
+    unsigned int dls_flags;    /* Indicates where this
+                                  directory came from */
+} Dl_serpath;
+.EE
+.in
+.IP
+The
+.I dls_flags
+field is currently unused, and always contains zero.
+.TP
+.BR RTLD_DI_SERINFOSIZE " (\fIDl_serinfo *\fP)"
+Populate the
+.I dls_size
+and
+.I dls_cnt
+fields of the
+.I Dl_serinfo
+structure pointed to by
+.I info
+with values suitable for allocating a buffer for use in a subsequent
+.B RTLD_DI_SERINFO
+request.
+.TP
+.BR RTLD_DI_TLS_MODID " (\fIsize_t *\fP, since glibc 2.4)"
+Obtain the module ID of this shared object's TLS (thread-local storage)
+segment, as used in TLS relocations.
+If this object does not define a TLS segment, zero is placed in
+.IR *info .
+.TP
+.BR RTLD_DI_TLS_DATA " (\fIvoid **\fP, since glibc 2.4)"
+Obtain a pointer to the calling
+thread's TLS block corresponding to this shared object's TLS segment.
+If this object does not define a PT_TLS segment,
+or if the calling thread has not allocated a block for it,
+NULL is placed in
+.IR *info .
+.SH RETURN VALUE
+On success,
+.BR dlinfo ()
+returns 0.
+On failure, it returns \-1; the cause of the error can be diagnosed using
+.BR dlerror (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dlinfo ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The sets of requests supported by the various implementations
+overlaps only partially.
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.3.3.
+Solaris.
+.SH EXAMPLES
+The program below opens a shared objects using
+.BR dlopen (3)
+and then uses the
+.B RTLD_DI_SERINFOSIZE
+and
+.B RTLD_DI_SERINFO
+requests to obtain the library search path list for the library.
+Here is an example of what we might see when running the program:
+.P
+.in +4n
+.EX
+$ \fB./a.out /lib64/libm.so.6\fP
+dls_serpath[0].dls_name = /lib64
+dls_serpath[1].dls_name = /usr/lib64
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (dlinfo.c)
+.EX
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <link.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    void *handle;
+    Dl_serinfo serinfo;
+    Dl_serinfo *sip;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <libpath>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Obtain a handle for shared object specified on command line. */
+\&
+    handle = dlopen(argv[1], RTLD_NOW);
+    if (handle == NULL) {
+        fprintf(stderr, "dlopen() failed: %s\en", dlerror());
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Discover the size of the buffer that we must pass to
+       RTLD_DI_SERINFO. */
+\&
+    if (dlinfo(handle, RTLD_DI_SERINFOSIZE, &serinfo) == \-1) {
+        fprintf(stderr, "RTLD_DI_SERINFOSIZE failed: %s\en", dlerror());
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Allocate the buffer for use with RTLD_DI_SERINFO. */
+\&
+    sip = malloc(serinfo.dls_size);
+    if (sip == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Initialize the \[aq]dls_size\[aq] and \[aq]dls_cnt\[aq] fields in the newly
+       allocated buffer. */
+\&
+    if (dlinfo(handle, RTLD_DI_SERINFOSIZE, sip) == \-1) {
+        fprintf(stderr, "RTLD_DI_SERINFOSIZE failed: %s\en", dlerror());
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Fetch and print library search list. */
+\&
+    if (dlinfo(handle, RTLD_DI_SERINFO, sip) == \-1) {
+        fprintf(stderr, "RTLD_DI_SERINFO failed: %s\en", dlerror());
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (size_t j = 0; j < serinfo.dls_cnt; j++)
+        printf("dls_serpath[%zu].dls_name = %s\en",
+               j, sip\->dls_serpath[j].dls_name);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR dl_iterate_phdr (3),
+.BR dladdr (3),
+.BR dlerror (3),
+.BR dlopen (3),
+.BR dlsym (3),
+.BR ld.so (8)
diff --git a/man/man3/dlmopen.3 b/man/man3/dlmopen.3
new file mode 100644
index 000000000..15d096806
--- /dev/null
+++ b/man/man3/dlmopen.3
@@ -0,0 +1 @@
+.so man3/dlopen.3
diff --git a/man/man3/dlopen.3 b/man/man3/dlopen.3
new file mode 100644
index 000000000..03fbc04e1
--- /dev/null
+++ b/man/man3/dlopen.3
@@ -0,0 +1,624 @@
+'\" t
+.\" Copyright 1995 Yggdrasil Computing, Incorporated.
+.\" written by Adam J. Richter (adam@yggdrasil.com),
+.\" with typesetting help from Daniel Quinlan (quinlan@yggdrasil.com).
+.\" and Copyright 2003, 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified by David A. Wheeler <dwheeler@dwheeler.com> 2000-11-28.
+.\" Applied patch by Terran Melconian, aeb, 2001-12-14.
+.\" Modified by Hacksaw <hacksaw@hacksaw.org> 2003-03-13.
+.\" Modified by Matt Domsch, 2003-04-09: _init and _fini obsolete
+.\" Modified by Michael Kerrisk <mtk.manpages@gmail.com> 2003-05-16.
+.\" Modified by Walter Harms: dladdr, dlvsym
+.\" Modified by Petr Baudis <pasky@suse.cz>, 2008-12-04: dladdr caveat
+.\"
+.TH dlopen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dlclose, dlopen, dlmopen \-
+open and close a shared object
+.SH LIBRARY
+Dynamic linking library
+.RI ( libdl ", " \-ldl )
+.SH SYNOPSIS
+.nf
+.B #include <dlfcn.h>
+.P
+.BI "void *dlopen(const char *" filename ", int " flags );
+.BI "int dlclose(void *" handle );
+.P
+.B #define _GNU_SOURCE
+.br
+.B #include <dlfcn.h>
+.P
+.BI "void *dlmopen(Lmid_t " lmid ", const char *" filename ", int " flags );
+.fi
+.SH DESCRIPTION
+.SS dlopen()
+The function
+.BR dlopen ()
+loads the dynamic shared object (shared library)
+file named by the null-terminated
+string
+.I filename
+and returns an opaque "handle" for the loaded object.
+This handle is employed with other functions in the dlopen API, such as
+.BR dlsym (3),
+.BR dladdr (3),
+.BR dlinfo (3),
+and
+.BR dlclose ().
+.P
+If
+.I filename
+.\" FIXME On Solaris, when handle is NULL, we seem to get back
+.\" a handle for (something like) the root of the namespace.
+.\" The point here is that if we do a dlmopen(LM_ID_NEWLM), then
+.\" the filename==NULL case returns a different handle than
+.\" in the initial namespace. But, on glibc, the same handle is
+.\" returned. This is probably a bug in glibc.
+.\"
+is NULL, then the returned handle is for the main program.
+If
+.I filename
+contains a slash ("/"), then it is interpreted as a (relative
+or absolute) pathname.
+Otherwise, the dynamic linker searches for the object as follows
+(see
+.BR ld.so (8)
+for further details):
+.IP \[bu] 3
+(ELF only) If the calling object
+(i.e., the shared library or executable from which
+.BR dlopen ()
+is called)
+contains a DT_RPATH tag, and does not contain a DT_RUNPATH tag,
+then the directories listed in the DT_RPATH tag are searched.
+.IP \[bu]
+If, at the time that the program was started, the environment variable
+.B LD_LIBRARY_PATH
+was defined to contain a colon-separated list of directories,
+then these are searched.
+(As a security measure, this variable is ignored for set-user-ID and
+set-group-ID programs.)
+.IP \[bu]
+(ELF only) If the calling object
+contains a DT_RUNPATH tag, then the directories listed in that tag
+are searched.
+.IP \[bu]
+The cache file
+.I /etc/ld.so.cache
+(maintained by
+.BR ldconfig (8))
+is checked to see whether it contains an entry for
+.IR filename .
+.IP \[bu]
+The directories
+.I /lib
+and
+.I /usr/lib
+are searched (in that order).
+.P
+If the object specified by
+.I filename
+has dependencies on other shared objects,
+then these are also automatically loaded by the dynamic linker
+using the same rules.
+(This process may occur recursively,
+if those objects in turn have dependencies, and so on.)
+.P
+One of the following two values must be included in
+.IR flags :
+.TP
+.B RTLD_LAZY
+Perform lazy binding.
+Resolve symbols only as the code that references them is executed.
+If the symbol is never referenced, then it is never resolved.
+(Lazy binding is performed only for function references;
+references to variables are always immediately bound when
+the shared object is loaded.)
+Since glibc 2.1.1,
+.\" commit 12b5b6b7f78ea111e89bbf638294a5413c791072
+this flag is overridden by the effect of the
+.B LD_BIND_NOW
+environment variable.
+.TP
+.B RTLD_NOW
+If this value is specified, or the environment variable
+.B LD_BIND_NOW
+is set to a nonempty string,
+all undefined symbols in the shared object are resolved before
+.BR dlopen ()
+returns.
+If this cannot be done, an error is returned.
+.P
+Zero or more of the following values may also be ORed in
+.IR flags :
+.TP
+.B RTLD_GLOBAL
+The symbols defined by this shared object will be
+made available for symbol resolution of subsequently loaded shared objects.
+.TP
+.B RTLD_LOCAL
+This is the converse of
+.BR RTLD_GLOBAL ,
+and the default if neither flag is specified.
+Symbols defined in this shared object are not made available to resolve
+references in subsequently loaded shared objects.
+.TP
+.BR RTLD_NODELETE " (since glibc 2.2)"
+Do not unload the shared object during
+.BR dlclose ().
+Consequently, the object's static and global variables are not reinitialized
+if the object is reloaded with
+.BR dlopen ()
+at a later time.
+.TP
+.BR RTLD_NOLOAD " (since glibc 2.2)"
+Don't load the shared object.
+This can be used to test if the object is already resident
+.RB ( dlopen ()
+returns NULL if it is not, or the object's handle if it is resident).
+This flag can also be used to promote the flags on a shared object
+that is already loaded.
+For example, a shared object that was previously loaded with
+.B RTLD_LOCAL
+can be reopened with
+.BR RTLD_NOLOAD\ |\ RTLD_GLOBAL .
+.\"
+.TP
+.BR RTLD_DEEPBIND " (since glibc 2.3.4)"
+.\" Inimitably described by UD in
+.\" http://sources.redhat.com/ml/libc-hacker/2004-09/msg00083.html.
+Place the lookup scope of the symbols in this
+shared object ahead of the global scope.
+This means that a self-contained object will use
+its own symbols in preference to global symbols with the same name
+contained in objects that have already been loaded.
+.P
+If
+.I filename
+is NULL, then the returned handle is for the main program.
+When given to
+.BR dlsym (3),
+this handle causes a search for a symbol in the main program,
+followed by all shared objects loaded at program startup,
+and then all shared objects loaded by
+.BR dlopen ()
+with the flag
+.BR RTLD_GLOBAL .
+.P
+Symbol references in the shared object are resolved using (in order):
+symbols in the link map of objects loaded for the main program and its
+dependencies;
+symbols in shared objects (and their dependencies)
+that were previously opened with
+.BR dlopen ()
+using the
+.B RTLD_GLOBAL
+flag;
+and definitions in the shared object itself
+(and any dependencies that were loaded for that object).
+.P
+Any global symbols in the executable that were placed into
+its dynamic symbol table by
+.BR ld (1)
+can also be used to resolve references in a dynamically loaded shared object.
+Symbols may be placed in the dynamic symbol table
+either because the executable was linked with the flag "\-rdynamic"
+(or, synonymously, "\-\-export\-dynamic"), which causes all of
+the executable's global symbols to be placed in the dynamic symbol table,
+or because
+.BR ld (1)
+noted a dependency on a symbol in another object during static linking.
+.P
+If the same shared object is opened again with
+.BR dlopen (),
+the same object handle is returned.
+The dynamic linker maintains reference
+counts for object handles, so a dynamically loaded shared object is not
+deallocated until
+.BR dlclose ()
+has been called on it as many times as
+.BR dlopen ()
+has succeeded on it.
+Constructors (see below) are called only when the object is actually loaded
+into memory (i.e., when the reference count increases to 1).
+.P
+A subsequent
+.BR dlopen ()
+call that loads the same shared object with
+.B RTLD_NOW
+may force symbol resolution for a shared object earlier loaded with
+.BR RTLD_LAZY .
+Similarly, an object that was previously opened with
+.B RTLD_LOCAL
+can be promoted to
+.B RTLD_GLOBAL
+in a subsequent
+.BR dlopen ().
+.P
+If
+.BR dlopen ()
+fails for any reason, it returns NULL.
+.\"
+.SS dlmopen()
+This function performs the same task as
+.BR dlopen ()\[em]the
+.I filename
+and
+.I flags
+arguments, as well as the return value, are the same,
+except for the differences noted below.
+.P
+The
+.BR dlmopen ()
+function differs from
+.BR dlopen ()
+primarily in that it accepts an additional argument,
+.IR lmid ,
+that specifies the link-map list (also referred to as a
+.IR namespace )
+in which the shared object should be loaded.
+(By comparison,
+.BR dlopen ()
+adds the dynamically loaded shared object to the same namespace as
+the shared object from which the
+.BR dlopen ()
+call is made.)
+The
+.I Lmid_t
+type is an opaque handle that refers to a namespace.
+.P
+The
+.I lmid
+argument is either the ID of an existing namespace
+.\" FIXME: Is using dlinfo() RTLD_DI_LMID the right technique?
+(which can be obtained using the
+.BR dlinfo (3)
+.B RTLD_DI_LMID
+request) or one of the following special values:
+.TP
+.B LM_ID_BASE
+Load the shared object in the initial namespace
+(i.e., the application's namespace).
+.TP
+.B LM_ID_NEWLM
+Create a new namespace and load the shared object in that namespace.
+The object must have been correctly linked
+to reference all of the other shared objects that it requires,
+since the new namespace is initially empty.
+.P
+If
+.I filename
+is NULL, then the only permitted value for
+.I lmid
+is
+.BR LM_ID_BASE .
+.SS dlclose()
+The function
+.BR dlclose ()
+decrements the reference count on the
+dynamically loaded shared object referred to by
+.IR handle .
+.P
+If the object's reference count drops to zero
+and no symbols in this object are required by other objects,
+then the object is unloaded
+after first calling any destructors defined for the object.
+(Symbols in this object might be required in another object
+because this object was opened with the
+.B RTLD_GLOBAL
+flag and one of its symbols satisfied a relocation in another object.)
+.P
+All shared objects that were automatically loaded when
+.BR dlopen ()
+was invoked on the object referred to by
+.I handle
+are recursively closed in the same manner.
+.P
+A successful return from
+.BR dlclose ()
+does not guarantee that the symbols associated with
+.I handle
+are removed from the caller's address space.
+In addition to references resulting from explicit
+.BR dlopen ()
+calls, a shared object may have been implicitly loaded
+(and reference counted) because of dependencies in other shared objects.
+Only when all references have been released can the shared object
+be removed from the address space.
+.SH RETURN VALUE
+On success,
+.BR dlopen ()
+and
+.BR dlmopen ()
+return a non-NULL handle for the loaded object.
+On error
+(file could not be found, was not readable, had the wrong format,
+or caused errors during loading),
+these functions return NULL.
+.P
+On success,
+.BR dlclose ()
+returns 0; on error, it returns a nonzero value.
+.P
+Errors from these functions can be diagnosed using
+.BR dlerror (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dlopen (),
+.BR dlmopen (),
+.BR dlclose ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR dlopen ()
+.TQ
+.BR dlclose ()
+POSIX.1-2008.
+.TP
+.BR dlmopen ()
+.TQ
+.B RTLD_NOLOAD
+.TQ
+.B RTLD_NODELETE
+GNU.
+.TP
+.B RTLD_DEEPBIND
+Solaris.
+.SH HISTORY
+.TP
+.BR dlopen ()
+.TQ
+.BR dlclose ()
+glibc 2.0.
+POSIX.1-2001.
+.TP
+.BR dlmopen ()
+glibc 2.3.4.
+.SH NOTES
+.SS dlmopen() and namespaces
+A link-map list defines an isolated namespace for the
+resolution of symbols by the dynamic linker.
+Within a namespace,
+dependent shared objects are implicitly loaded according to the usual rules,
+and symbol references are likewise resolved according to the usual rules,
+but such resolution is confined to the definitions provided by the
+objects that have been (explicitly and implicitly) loaded into the namespace.
+.P
+The
+.BR dlmopen ()
+function permits object-load isolation\[em]the ability
+to load a shared object in a new namespace without
+exposing the rest of the application to the symbols
+made available by the new object.
+Note that the use of the
+.B RTLD_LOCAL
+flag is not sufficient for this purpose,
+since it prevents a shared object's symbols from being available to
+.I any
+other shared object.
+In some cases,
+we may want to make the symbols provided by a dynamically
+loaded shared object available to (a subset of) other shared objects
+without exposing those symbols to the entire application.
+This can be achieved by using a separate namespace and the
+.B RTLD_GLOBAL
+flag.
+.P
+The
+.BR dlmopen ()
+function also can be used to provide better isolation than the
+.B RTLD_LOCAL
+flag.
+In particular, shared objects loaded with
+.B RTLD_LOCAL
+may be promoted to
+.B RTLD_GLOBAL
+if they are dependencies of another shared object loaded with
+.BR RTLD_GLOBAL .
+Thus,
+.B RTLD_LOCAL
+is insufficient to isolate a loaded shared object except in the (uncommon)
+case where one has explicit control over all shared object dependencies.
+.P
+Possible uses of
+.BR dlmopen ()
+are plugins where the author of the plugin-loading framework
+can't trust the plugin authors and does not wish
+any undefined symbols from the plugin framework to be resolved to plugin
+symbols.
+Another use is to load the same object more than once.
+Without the use of
+.BR dlmopen (),
+this would require the creation of distinct copies of the shared object file.
+Using
+.BR dlmopen (),
+this can be achieved by loading the same shared object file into
+different namespaces.
+.P
+The glibc implementation supports a maximum of
+.\" DL_NNS
+16 namespaces.
+.\"
+.SS Initialization and finalization functions
+Shared objects may export functions using the
+.B __attribute__((constructor))
+and
+.B __attribute__((destructor))
+function attributes.
+Constructor functions are executed before
+.BR dlopen ()
+returns, and destructor functions are executed before
+.BR dlclose ()
+returns.
+A shared object may export multiple constructors and destructors,
+and priorities can be associated with each function
+to determine the order in which they are executed.
+See the
+.B gcc
+info pages (under "Function attributes")
+.\" info gcc "C Extensions" "Function attributes"
+for further information.
+.P
+An older method of (partially) achieving the same result is via the use of
+two special symbols recognized by the linker:
+.B _init
+and
+.BR _fini .
+If a dynamically loaded shared object exports a routine named
+.BR _init (),
+then that code is executed after loading a shared object, before
+.BR dlopen ()
+returns.
+If the shared object exports a routine named
+.BR _fini (),
+then that routine is called just before the object is unloaded.
+In this case, one must avoid linking against the system startup files,
+which contain default versions of these files;
+this can be done by using the
+.BR gcc (1)
+.I \-nostartfiles
+command-line option.
+.P
+Use of
+.B _init
+and
+.B _fini
+is now deprecated in favor of the aforementioned
+constructors and destructors,
+which among other advantages,
+permit multiple initialization and finalization functions to be defined.
+.\"
+.\" Using these routines, or the gcc
+.\" .B \-nostartfiles
+.\" or
+.\" .B \-nostdlib
+.\" options, is not recommended.
+.\" Their use may result in undesired behavior,
+.\" since the constructor/destructor routines will not be executed
+.\" (unless special measures are taken).
+.\" .\" void _init(void) __attribute__((constructor));
+.\" .\" void _fini(void) __attribute__((destructor));
+.\"
+.P
+Since glibc 2.2.3,
+.BR atexit (3)
+can be used to register an exit handler that is automatically
+called when a shared object is unloaded.
+.SS History
+These functions are part of the dlopen API, derived from SunOS.
+.SH BUGS
+As at glibc 2.24, specifying the
+.B RTLD_GLOBAL
+flag when calling
+.BR dlmopen ()
+.\" dlerror(): "invalid mode"
+generates an error.
+Furthermore, specifying
+.B RTLD_GLOBAL
+when calling
+.BR dlopen ()
+results in a program crash
+.RB ( SIGSEGV )
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=18684
+if the call is made from any object loaded in a
+namespace other than the initial namespace.
+.SH EXAMPLES
+The program below loads the (glibc) math library,
+looks up the address of the
+.BR cos (3)
+function, and prints the cosine of 2.0.
+The following is an example of building and running the program:
+.P
+.in +4n
+.EX
+$ \fBcc dlopen_demo.c \-ldl\fP
+$ \fB./a.out\fP
+\-0.416147
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (dlopen.c)
+.EX
+#include <dlfcn.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#include <gnu/lib\-names.h>  /* Defines LIBM_SO (which will be a
+                               string such as "libm.so.6") */
+int
+main(void)
+{
+    void *handle;
+    double (*cosine)(double);
+    char *error;
+\&
+    handle = dlopen(LIBM_SO, RTLD_LAZY);
+    if (!handle) {
+        fprintf(stderr, "%s\en", dlerror());
+        exit(EXIT_FAILURE);
+    }
+\&
+    dlerror();    /* Clear any existing error */
+\&
+    cosine = (double (*)(double)) dlsym(handle, "cos");
+\&
+    /* According to the ISO C standard, casting between function
+       pointers and \[aq]void *\[aq], as done above, produces undefined results.
+       POSIX.1\-2001 and POSIX.1\-2008 accepted this state of affairs and
+       proposed the following workaround:
+\&
+           *(void **) (&cosine) = dlsym(handle, "cos");
+\&
+       This (clumsy) cast conforms with the ISO C standard and will
+       avoid any compiler warnings.
+\&
+       The 2013 Technical Corrigendum 1 to POSIX.1\-2008 improved matters
+       by requiring that conforming implementations support casting
+       \[aq]void *\[aq] to a function pointer.  Nevertheless, some compilers
+       (e.g., gcc with the \[aq]\-pedantic\[aq] option) may complain about the
+       cast used in this program. */
+.\" http://pubs.opengroup.org/onlinepubs/009695399/functions/dlsym.html#tag_03_112_08
+.\" http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlsym.html#tag_16_96_07
+.\" http://austingroupbugs.net/view.php?id=74
+\&
+    error = dlerror();
+    if (error != NULL) {
+        fprintf(stderr, "%s\en", error);
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("%f\en", (*cosine)(2.0));
+    dlclose(handle);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ld (1),
+.BR ldd (1),
+.BR pldd (1),
+.BR dl_iterate_phdr (3),
+.BR dladdr (3),
+.BR dlerror (3),
+.BR dlinfo (3),
+.BR dlsym (3),
+.BR rtld\-audit (7),
+.BR ld.so (8),
+.BR ldconfig (8)
+.P
+gcc info pages, ld info pages
diff --git a/man/man3/dlsym.3 b/man/man3/dlsym.3
new file mode 100644
index 000000000..74cc36af2
--- /dev/null
+++ b/man/man3/dlsym.3
@@ -0,0 +1,171 @@
+'\" t
+.\" Copyright 1995 Yggdrasil Computing, Incorporated.
+.\" and Copyright 2003, 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH dlsym 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dlsym, dlvsym \- obtain address of a symbol in a shared object or executable
+.SH LIBRARY
+Dynamic linking library
+.RI ( libdl ", " \-ldl )
+.SH SYNOPSIS
+.nf
+.B #include <dlfcn.h>
+.P
+.BI "void *dlsym(void *restrict " handle ", const char *restrict " symbol );
+.P
+.B #define _GNU_SOURCE
+.B #include <dlfcn.h>
+.P
+.BI "void *dlvsym(void *restrict " handle ", const char *restrict " symbol ,
+.BI "             const char *restrict " version );
+.fi
+.SH DESCRIPTION
+The function
+.BR dlsym ()
+takes a "handle" of a dynamic loaded shared object returned by
+.BR dlopen (3)
+along with a null-terminated symbol name,
+and returns the address where that symbol is
+loaded into memory.
+If the symbol is not found, in the specified
+object or any of the shared objects that were automatically loaded by
+.BR dlopen (3)
+when that object was loaded,
+.BR dlsym ()
+returns NULL.
+(The search performed by
+.BR dlsym ()
+is breadth first through the dependency tree of these shared objects.)
+.P
+In unusual cases (see NOTES) the value of the symbol could actually be NULL.
+Therefore, a NULL return from
+.BR dlsym ()
+need not indicate an error.
+The correct way to distinguish an error from a symbol whose value is NULL
+is to call
+.BR dlerror (3)
+to clear any old error conditions, then call
+.BR dlsym (),
+and then call
+.BR dlerror (3)
+again, saving its return value into a variable, and check whether
+this saved value is not NULL.
+.P
+There are two special pseudo-handles that may be specified in
+.IR handle :
+.TP
+.B RTLD_DEFAULT
+Find the first occurrence of the desired symbol
+using the default shared object search order.
+The search will include global symbols in the executable
+and its dependencies,
+as well as symbols in shared objects that were dynamically loaded with the
+.B RTLD_GLOBAL
+flag.
+.TP
+.B RTLD_NEXT
+Find the next occurrence of the desired symbol in the search order
+after the current object.
+This allows one to provide a wrapper
+around a function in another shared object, so that, for example,
+the definition of a function in a preloaded shared object
+(see
+.B LD_PRELOAD
+in
+.BR ld.so (8))
+can find and invoke the "real" function provided in another shared object
+(or for that matter, the "next" definition of the function in cases
+where there are multiple layers of preloading).
+.P
+The
+.B _GNU_SOURCE
+feature test macro must be defined in order to obtain the
+definitions of
+.B RTLD_DEFAULT
+and
+.B RTLD_NEXT
+from
+.IR <dlfcn.h> .
+.P
+The function
+.BR dlvsym ()
+does the same as
+.BR dlsym ()
+but takes a version string as an additional argument.
+.SH RETURN VALUE
+On success,
+these functions return the address associated with
+.IR symbol .
+On failure, they return NULL;
+the cause of the error can be diagnosed using
+.BR dlerror (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dlsym (),
+.BR dlvsym ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR dlsym ()
+POSIX.1-2008.
+.TP
+.BR dlvsym ()
+GNU.
+.SH HISTORY
+.TP
+.BR dlsym ()
+glibc 2.0.
+POSIX.1-2001.
+.TP
+.BR dlvsym ()
+glibc 2.1.
+.SH NOTES
+There are several scenarios when the address of a global symbol is NULL.
+For example, a symbol can be placed at zero address by the linker, via
+a linker script or with
+.I \-\-defsym
+command-line option.
+Undefined weak symbols also have NULL value.
+Finally, the symbol value may be the result of
+a GNU indirect function (IFUNC) resolver function that returns
+NULL as the resolved value.
+In the latter case,
+.BR dlsym ()
+also returns NULL without error.
+However, in the former two cases, the
+behavior of GNU dynamic linker is inconsistent: relocation processing
+succeeds and the symbol can be observed to have NULL value, but
+.BR dlsym ()
+fails and
+.BR dlerror ()
+indicates a lookup error.
+.\"
+.SS History
+The
+.BR dlsym ()
+function is part of the dlopen API, derived from SunOS.
+That system does not have
+.BR dlvsym ().
+.SH EXAMPLES
+See
+.BR dlopen (3).
+.SH SEE ALSO
+.BR dl_iterate_phdr (3),
+.BR dladdr (3),
+.BR dlerror (3),
+.BR dlinfo (3),
+.BR dlopen (3),
+.BR ld.so (8)
diff --git a/man/man3/dlvsym.3 b/man/man3/dlvsym.3
new file mode 100644
index 000000000..df2ca09f4
--- /dev/null
+++ b/man/man3/dlvsym.3
@@ -0,0 +1 @@
+.so man3/dlsym.3
diff --git a/man/man3/dn_comp.3 b/man/man3/dn_comp.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/dn_comp.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/dn_expand.3 b/man/man3/dn_expand.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/dn_expand.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/dprintf.3 b/man/man3/dprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/dprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/drand48.3 b/man/man3/drand48.3
new file mode 100644
index 000000000..108fe0f44
--- /dev/null
+++ b/man/man3/drand48.3
@@ -0,0 +1,262 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:46:03 1993 by Rik Faith (faith@cs.unc.edu)
+.TH drand48 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48,
+lcong48 \- generate uniformly distributed pseudo-random numbers
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.B double drand48(void);
+.BI "double erand48(unsigned short " xsubi [3]);
+.P
+.B long lrand48(void);
+.BI "long nrand48(unsigned short " xsubi [3]);
+.P
+.B long mrand48(void);
+.BI "long jrand48(unsigned short " xsubi [3]);
+.P
+.BI "void srand48(long " seedval );
+.BI "unsigned short *seed48(unsigned short " seed16v [3]);
+.BI "void lcong48(unsigned short " param [7]);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.\" .BR drand48 (),
+.\" .BR erand48 (),
+.\" .BR lrand48 (),
+.\" .BR nrand48 (),
+.\" .BR mrand48 (),
+.\" .BR jrand48 (),
+.\" .BR srand48 (),
+.\" .BR seed48 (),
+.\" .BR lcong48 ():
+.nf
+    _XOPEN_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions generate pseudo-random numbers using the linear congruential
+algorithm and 48-bit integer arithmetic.
+.P
+The
+.BR drand48 ()
+and
+.BR erand48 ()
+functions return nonnegative
+double-precision floating-point values uniformly distributed over the interval
+[0.0,\ 1.0).
+.P
+The
+.BR lrand48 ()
+and
+.BR nrand48 ()
+functions return nonnegative
+long integers uniformly distributed over the interval [0,\ 2\[ha]31).
+.P
+The
+.BR mrand48 ()
+and
+.BR jrand48 ()
+functions return signed long
+integers uniformly distributed over the interval [\-2\[ha]31,\ 2\[ha]31).
+.P
+The
+.BR srand48 (),
+.BR seed48 (),
+and
+.BR lcong48 ()
+functions are
+initialization functions, one of which should be called before using
+.BR drand48 (),
+.BR lrand48 (),
+or
+.BR mrand48 ().
+The functions
+.BR erand48 (),
+.BR nrand48 (),
+and
+.BR jrand48 ()
+do not require
+an initialization function to be called first.
+.P
+All the functions work by generating a sequence of 48-bit integers,
+.IR Xi ,
+according to the linear congruential formula:
+.P
+.in +4n
+.EX
+.B Xn+1 = (aXn + c) mod m,   where n >= 0
+.EE
+.in
+.P
+The parameter
+.I m
+= 2\[ha]48, hence 48-bit integer arithmetic is performed.
+Unless
+.BR lcong48 ()
+is called,
+.I a
+and
+.I c
+are given by:
+.P
+.in +4n
+.EX
+.B a = 0x5DEECE66D
+.B c = 0xB
+.EE
+.in
+.P
+The value returned by any of the functions
+.BR drand48 (),
+.BR erand48 (),
+.BR lrand48 (),
+.BR nrand48 (),
+.BR mrand48 (),
+or
+.BR jrand48 ()
+is
+computed by first generating the next 48-bit
+.I Xi
+in the sequence.
+Then the appropriate number of bits, according to the type of data item to
+be returned, is copied from the high-order bits of
+.I Xi
+and transformed
+into the returned value.
+.P
+The functions
+.BR drand48 (),
+.BR lrand48 (),
+and
+.BR mrand48 ()
+store
+the last 48-bit
+.I Xi
+generated in an internal buffer.
+The functions
+.BR erand48 (),
+.BR nrand48 (),
+and
+.BR jrand48 ()
+require the calling
+program to provide storage for the successive
+.I Xi
+values in the array
+argument
+.IR xsubi .
+The functions are initialized by placing the initial
+value of
+.I Xi
+into the array before calling the function for the first
+time.
+.P
+The initializer function
+.BR srand48 ()
+sets the high order 32-bits of
+.I Xi
+to the argument
+.IR seedval .
+The low order 16-bits are set
+to the arbitrary value 0x330E.
+.P
+The initializer function
+.BR seed48 ()
+sets the value of
+.I Xi
+to
+the 48-bit value specified in the array argument
+.IR seed16v .
+The
+previous value of
+.I Xi
+is copied into an internal buffer and a
+pointer to this buffer is returned by
+.BR seed48 ().
+.P
+The initialization function
+.BR lcong48 ()
+allows the user to specify
+initial values for
+.IR Xi ,
+.IR a ,
+and
+.IR c .
+Array argument
+elements
+.I param[0\-2]
+specify
+.IR Xi ,
+.I param[3\-5]
+specify
+.IR a ,
+and
+.I param[6]
+specifies
+.IR c .
+After
+.BR lcong48 ()
+has been called, a subsequent call to either
+.BR srand48 ()
+or
+.BR seed48 ()
+will restore the standard values of
+.I a
+and
+.IR c .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR drand48 (),
+.BR erand48 (),
+.BR lrand48 (),
+.BR nrand48 (),
+.BR mrand48 (),
+.BR jrand48 (),
+.BR srand48 (),
+.BR seed48 (),
+.BR lcong48 ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:drand48
+T}
+.TE
+.P
+The above
+functions record global state information for the random number generator,
+so they are not thread-safe.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.SH SEE ALSO
+.BR rand (3),
+.BR random (3)
diff --git a/man/man3/drand48_r.3 b/man/man3/drand48_r.3
new file mode 100644
index 000000000..13f893246
--- /dev/null
+++ b/man/man3/drand48_r.3
@@ -0,0 +1,104 @@
+'\" t
+.\" Copyright 2003 Walter Harms, 2004 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Created 2004-10-31. Text taken from a page by Walter Harms, 2003-09-08
+.\"
+.TH drand48_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+drand48_r, erand48_r, lrand48_r, nrand48_r, mrand48_r, jrand48_r,
+srand48_r, seed48_r, lcong48_r
+\- generate uniformly distributed pseudo-random numbers reentrantly
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int drand48_r(struct drand48_data *restrict " buffer ,
+.BI "              double *restrict " result );
+.BI "int erand48_r(unsigned short " xsubi [3] ","
+.BI "              struct drand48_data *restrict "buffer ,
+.BI "              double *restrict " result ");"
+.P
+.BI "int lrand48_r(struct drand48_data *restrict " buffer ,
+.BI "              long *restrict " result );
+.BI "int nrand48_r(unsigned short " xsubi[3] ","
+.BI "              struct drand48_data *restrict "buffer ,
+.BI "              long *restrict " result ");"
+.P
+.BI "int mrand48_r(struct drand48_data *restrict " buffer ,
+.BI "              long *restrict " result ");"
+.BI "int jrand48_r(unsigned short " xsubi[3] ","
+.BI "              struct drand48_data *restrict " buffer ,
+.BI "              long *restrict " result ");"
+.P
+.BI "int srand48_r(long int " seedval ", struct drand48_data *" buffer ");"
+.BI "int seed48_r(unsigned short " seed16v[3] ", struct drand48_data *" buffer );
+.BI "int lcong48_r(unsigned short " param[7] ", struct drand48_data *" buffer );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.\" .BR drand48_r (),
+.\" .BR erand48_r (),
+.\" .BR lrand48_r (),
+.\" .BR nrand48_r (),
+.\" .BR mrand48_r (),
+.\" .BR jrand48_r (),
+.\" .BR srand48_r (),
+.\" .BR seed48_r (),
+.\" .BR lcong48_r ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+These functions are the reentrant analogs of the functions described in
+.BR drand48 (3).
+Instead of modifying the global random generator state, they use
+the supplied data
+.IR buffer .
+.P
+Before the first use, this struct must be initialized, for example,
+by filling it with zeros, or by calling one of the functions
+.BR srand48_r (),
+.BR seed48_r (),
+or
+.BR lcong48_r ().
+.SH RETURN VALUE
+The return value is 0.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR drand48_r (),
+.BR erand48_r (),
+.BR lrand48_r (),
+.BR nrand48_r (),
+.BR mrand48_r (),
+.BR jrand48_r (),
+.BR srand48_r (),
+.BR seed48_r (),
+.BR lcong48_r ()
+T}	Thread safety	MT-Safe race:buffer
+.TE
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR drand48 (3),
+.BR rand (3),
+.BR random (3)
diff --git a/man/man3/drem.3 b/man/man3/drem.3
new file mode 100644
index 000000000..b7a5b23bf
--- /dev/null
+++ b/man/man3/drem.3
@@ -0,0 +1 @@
+.so man3/remainder.3
diff --git a/man/man3/dremf.3 b/man/man3/dremf.3
new file mode 100644
index 000000000..b7a5b23bf
--- /dev/null
+++ b/man/man3/dremf.3
@@ -0,0 +1 @@
+.so man3/remainder.3
diff --git a/man/man3/dreml.3 b/man/man3/dreml.3
new file mode 100644
index 000000000..b7a5b23bf
--- /dev/null
+++ b/man/man3/dreml.3
@@ -0,0 +1 @@
+.so man3/remainder.3
diff --git a/man/man3/duplocale.3 b/man/man3/duplocale.3
new file mode 100644
index 000000000..246af79e9
--- /dev/null
+++ b/man/man3/duplocale.3
@@ -0,0 +1,168 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH duplocale 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+duplocale \- duplicate a locale object
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <locale.h>
+.P
+.BI "locale_t duplocale(locale_t " locobj );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR duplocale ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR duplocale ()
+function creates a duplicate of the locale object referred to by
+.IR locobj .
+.P
+If
+.I locobj
+is
+.BR LC_GLOBAL_LOCALE ,
+.BR duplocale ()
+creates a locale object containing a copy of the global locale
+determined by
+.BR setlocale (3).
+.SH RETURN VALUE
+On success,
+.BR duplocale ()
+returns a handle for the new locale object.
+On error, it returns
+.IR "(locale_t)\ 0",
+and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient memory to create the duplicate locale object.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.3.
+.SH NOTES
+Duplicating a locale can serve the following purposes:
+.IP \[bu] 3
+To create a copy of a locale object in which one of more categories
+are to be modified (using
+.BR newlocale (3)).
+.IP \[bu]
+To obtain a handle for the current locale which can used in
+other functions that employ a locale handle, such as
+.BR toupper_l (3).
+This is done by applying
+.BR duplocale ()
+to the value returned by the following call:
+.IP
+.in +4n
+.EX
+loc = uselocale((locale_t) 0);
+.EE
+.in
+.IP
+This technique is necessary, because the above
+.BR uselocale (3)
+call may return the value
+.BR LC_GLOBAL_LOCALE ,
+which results in undefined behavior if passed to functions such as
+.BR toupper_l (3).
+Calling
+.BR duplocale ()
+can be used to ensure that the
+.B LC_GLOBAL_LOCALE
+value is converted into a usable locale object.
+See EXAMPLES, below.
+.P
+Each locale object created by
+.BR duplocale ()
+should be deallocated using
+.BR  freelocale (3).
+.SH EXAMPLES
+The program below uses
+.BR uselocale (3)
+and
+.BR duplocale ()
+to obtain a handle for the current locale which is then passed to
+.BR toupper_l (3).
+The program takes one command-line argument,
+a string of characters that is converted to uppercase and
+displayed on standard output.
+An example of its use is the following:
+.P
+.in +4n
+.EX
+$ \fB./a.out abc\fP
+ABC
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (duplocale.c)
+.EX
+#define _XOPEN_SOURCE 700
+#include <ctype.h>
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+int
+main(int argc, char *argv[])
+{
+    locale_t loc, nloc;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s string\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* This sequence is necessary, because uselocale() might return
+       the value LC_GLOBAL_LOCALE, which can\[aq]t be passed as an
+       argument to toupper_l(). */
+\&
+    loc = uselocale((locale_t) 0);
+    if (loc == (locale_t) 0)
+        errExit("uselocale");
+\&
+    nloc = duplocale(loc);
+    if (nloc == (locale_t) 0)
+        errExit("duplocale");
+\&
+    for (char *p = argv[1]; *p; p++)
+        putchar(toupper_l(*p, nloc));
+\&
+    printf("\en");
+\&
+    freelocale(nloc);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR freelocale (3),
+.BR newlocale (3),
+.BR setlocale (3),
+.BR uselocale (3),
+.BR locale (5),
+.BR locale (7)
diff --git a/man/man3/dysize.3 b/man/man3/dysize.3
new file mode 100644
index 000000000..a6278f1bf
--- /dev/null
+++ b/man/man3/dysize.3
@@ -0,0 +1,69 @@
+'\" t
+.\"  Copyright 2001 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" aeb: some corrections
+.TH dysize 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dysize \- get number of days for a given year
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <time.h>"
+.P
+.BI "int dysize(int " year );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR dysize ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The function returns 365 for a normal year and 366 for a leap year.
+The calculation for leap year is based on:
+.P
+.in +4n
+.EX
+(year) %4 == 0 && ((year) %100 != 0 || (year) %400 == 0)
+.EE
+.in
+.P
+The formula is defined in the macro
+.I __isleap(year)
+also found in
+.IR <time.h> .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR dysize ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SunOS 4.x.
+.P
+This is a compatibility function only.
+Don't use it in new programs.
+.\" The SCO version of this function had a year-2000 problem.
+.SH SEE ALSO
+.BR strftime (3)
diff --git a/man/man3/eaccess.3 b/man/man3/eaccess.3
new file mode 100644
index 000000000..9e5035180
--- /dev/null
+++ b/man/man3/eaccess.3
@@ -0,0 +1 @@
+.so man3/euidaccess.3
diff --git a/man/man3/ecb_crypt.3 b/man/man3/ecb_crypt.3
new file mode 100644
index 000000000..853c9cbdf
--- /dev/null
+++ b/man/man3/ecb_crypt.3
@@ -0,0 +1 @@
+.so man3/des_crypt.3
diff --git a/man/man3/ecvt.3 b/man/man3/ecvt.3
new file mode 100644
index 000000000..48e25904e
--- /dev/null
+++ b/man/man3/ecvt.3
@@ -0,0 +1,133 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:40:39 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Jun 25 12:10:47 1999 by Andries Brouwer (aeb@cwi.nl)
+.\"
+.TH ecvt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ecvt, fcvt \- convert a floating-point number to a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "[[deprecated]] char *ecvt(double " number ", int " ndigits ,
+.BI "                          int *restrict " decpt ", int *restrict " sign );
+.BI "[[deprecated]] char *fcvt(double " number ", int " ndigits ,
+.BI "                          int *restrict " decpt ", int *restrict " sign );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ecvt (),
+.BR fcvt ():
+.nf
+    Since glibc 2.17
+        (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
+            || /* glibc >= 2.20 */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19 */ _SVID_SOURCE
+    glibc 2.12 to glibc 2.16:
+        (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
+            || _SVID_SOURCE
+    Before glibc 2.12:
+        _SVID_SOURCE || _XOPEN_SOURCE >= 500
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+The
+.BR ecvt ()
+function converts \fInumber\fP to a null-terminated
+string of \fIndigits\fP digits (where \fIndigits\fP is reduced to a
+system-specific limit determined by the precision of a
+.IR double ),
+and returns a pointer to the string.
+The high-order digit is nonzero, unless
+.I number
+is zero.
+The low order digit is rounded.
+The string itself does not contain a decimal point; however,
+the position of the decimal point relative to the start of the string
+is stored in \fI*decpt\fP.
+A negative value for \fI*decpt\fP means that
+the decimal point is to the left of the start of the string.
+If the sign of
+\fInumber\fP is negative, \fI*sign\fP is set to a nonzero value,
+otherwise it is set to 0.
+If
+.I number
+is zero, it is unspecified whether \fI*decpt\fP is 0 or 1.
+.P
+The
+.BR fcvt ()
+function is identical to
+.BR ecvt (),
+except that
+\fIndigits\fP specifies the number of digits after the decimal point.
+.SH RETURN VALUE
+Both the
+.BR ecvt ()
+and
+.BR fcvt ()
+functions return a pointer to a
+static string containing the ASCII representation of \fInumber\fP.
+The static string is overwritten by each call to
+.BR ecvt ()
+or
+.BR fcvt ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ecvt ()
+T}	Thread safety	MT-Unsafe race:ecvt
+T{
+.na
+.nh
+.BR fcvt ()
+T}	Thread safety	MT-Unsafe race:fcvt
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr2;
+marked as LEGACY in POSIX.1-2001.
+POSIX.1-2008 removes the specifications of
+.BR ecvt ()
+and
+.BR fcvt (),
+recommending the use of
+.BR sprintf (3)
+instead (though
+.BR snprintf (3)
+may be preferable).
+.SH NOTES
+.\" Linux libc4 and libc5 specified the type of
+.\" .I ndigits
+.\" as
+.\" .IR size_t .
+Not all locales use a point as the radix character ("decimal point").
+.SH SEE ALSO
+.BR ecvt_r (3),
+.BR gcvt (3),
+.BR qecvt (3),
+.BR setlocale (3),
+.BR sprintf (3)
diff --git a/man/man3/ecvt_r.3 b/man/man3/ecvt_r.3
new file mode 100644
index 000000000..34e32abb7
--- /dev/null
+++ b/man/man3/ecvt_r.3
@@ -0,0 +1,100 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" This replaces an earlier man page written by Walter Harms
+.\" <walter.harms@informatik.uni-oldenburg.de>.
+.\"
+.\" Corrected return types; from Fabian; 2004-10-05
+.\"
+.TH ecvt_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ecvt_r, fcvt_r, qecvt_r, qfcvt_r \- convert a floating-point number to a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "[[deprecated]] int ecvt_r(double " number ", int " ndigits ,
+.BI "                          int *restrict " decpt ", int *restrict " sign ,
+.BI "                          char *restrict " buf ", size_t " len );
+.BI "[[deprecated]] int fcvt_r(double " number ", int " ndigits ,
+.BI "                          int *restrict " decpt ", int *restrict " sign ,
+.BI "                          char *restrict " buf ", size_t " len );
+.P
+.BI "[[deprecated]] int qecvt_r(long double " number ", int " ndigits ,
+.BI "                          int *restrict " decpt ", int *restrict " sign ,
+.BI "                          char *restrict " buf ", size_t " len );
+.BI "[[deprecated]] int qfcvt_r(long double " number ", int " ndigits ,
+.BI "                          int *restrict " decpt ", int *restrict " sign ,
+.BI "                          char *restrict " buf ", size_t " len );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ecvt_r (),
+.BR fcvt_r (),
+.BR qecvt_r (),
+.BR qfcvt_r ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The functions
+.BR ecvt_r (),
+.BR fcvt_r (),
+.BR qecvt_r (),
+and
+.BR qfcvt_r ()
+are identical to
+.BR ecvt (3),
+.BR fcvt (3),
+.BR qecvt (3),
+and
+.BR qfcvt (3),
+respectively, except that they do not return their result in a static
+buffer, but instead use the supplied
+.I buf
+of size
+.IR len .
+See
+.BR ecvt (3)
+and
+.BR qecvt (3).
+.SH RETURN VALUE
+These functions return 0 on success, and \-1 otherwise.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ecvt_r (),
+.BR fcvt_r (),
+.BR qecvt_r (),
+.BR qfcvt_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH NOTES
+These functions are obsolete.
+Instead,
+.BR sprintf (3)
+is recommended.
+.SH SEE ALSO
+.BR ecvt (3),
+.BR qecvt (3),
+.BR sprintf (3)
diff --git a/man/man3/edata.3 b/man/man3/edata.3
new file mode 100644
index 000000000..94843fb05
--- /dev/null
+++ b/man/man3/edata.3
@@ -0,0 +1 @@
+.so man3/end.3
diff --git a/man/man3/encrypt.3 b/man/man3/encrypt.3
new file mode 100644
index 000000000..4ec5cd7fd
--- /dev/null
+++ b/man/man3/encrypt.3
@@ -0,0 +1,211 @@
+'\" t
+.\" Copyright 2000 Nicolás Lichtmaier <nick@debian.org>
+.\" Created 2000-07-22 00:52-0300
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 2002-07-23 19:21:35 CEST 2002 Walter Harms
+.\" <walter.harms@informatik.uni-oldenburg.de>
+.\"
+.\" Modified 2003-04-04, aeb
+.\"
+.TH encrypt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+encrypt, setkey, encrypt_r, setkey_r \- encrypt 64-bit messages
+.SH LIBRARY
+Password hashing library
+.RI ( libcrypt ", " \-lcrypt )
+.SH SYNOPSIS
+.nf
+.BR "#define _XOPEN_SOURCE" "       /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BI "[[deprecated]] void encrypt(char " block "[64], int " edflag );
+.P
+.BR "#define _XOPEN_SOURCE" "       /* See feature_test_macros(7) */"
+.B #include <stdlib.h>
+.P
+.BI "[[deprecated]] void setkey(const char *" key );
+.P
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <crypt.h>
+.P
+.BI "[[deprecated]] void setkey_r(const char *" key ", struct crypt_data *" data );
+.BI "[[deprecated]] void encrypt_r(char *" block ", int " edflag ,
+.BI "                              struct crypt_data *" data );
+.fi
+.SH DESCRIPTION
+These functions encrypt and decrypt 64-bit messages.
+The
+.BR setkey ()
+function sets the key used by
+.BR encrypt ().
+The
+.I key
+argument used here is an array of 64 bytes, each of which has
+numerical value 1 or 0.
+The bytes key[n] where n=8*i-1 are ignored,
+so that the effective key length is 56 bits.
+.P
+The
+.BR encrypt ()
+function modifies the passed buffer, encoding if
+.I edflag
+is 0, and decoding if 1 is being passed.
+Like the
+.I key
+argument, also
+.I block
+is a bit vector representation of the actual value that is encoded.
+The result is returned in that same vector.
+.P
+These two functions are not reentrant, that is, the key data is
+kept in static storage.
+The functions
+.BR setkey_r ()
+and
+.BR encrypt_r ()
+are the reentrant versions.
+They use the following
+structure to hold the key data:
+.P
+.in +4n
+.EX
+struct crypt_data {
+    char keysched[16 * 8];
+    char sb0[32768];
+    char sb1[32768];
+    char sb2[32768];
+    char sb3[32768];
+    char crypt_3_buf[14];
+    char current_salt[2];
+    long current_saltbits;
+    int  direction;
+    int  initialized;
+};
+.EE
+.in
+.P
+Before calling
+.BR setkey_r ()
+set
+.I data\->initialized
+to zero.
+.SH RETURN VALUE
+These functions do not return any value.
+.SH ERRORS
+Set
+.I errno
+to zero before calling the above functions.
+On success,
+.I errno
+is unchanged.
+.TP
+.B ENOSYS
+The function is not provided.
+(For example because of former USA export restrictions.)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR encrypt (),
+.BR setkey ()
+T}	Thread safety	MT-Unsafe race:crypt
+T{
+.na
+.nh
+.BR encrypt_r (),
+.BR setkey_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR encrypt ()
+.TQ
+.BR setkey ()
+POSIX.1-2008.
+.TP
+.BR encrypt_r ()
+.TQ
+.BR setkey_r ()
+None.
+.SH HISTORY
+Removed in glibc 2.28.
+.P
+Because they employ the DES block cipher,
+which is no longer considered secure,
+these functions were removed from glibc.
+Applications should switch to a modern cryptography library, such as
+.BR libgcrypt .
+.TP
+.BR encrypt ()
+.TQ
+.BR setkey ()
+POSIX.1-2001, SUS, SVr4.
+.SS Availability in glibc
+See
+.BR crypt (3).
+.SS Features in glibc
+In glibc 2.2, these functions use the DES algorithm.
+.SH EXAMPLES
+.\" SRC BEGIN (encrypt.c)
+.EX
+#define _XOPEN_SOURCE
+#include <crypt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(void)
+{
+    char key[64];
+    char orig[9] = "eggplant";
+    char buf[64];
+    char txt[9];
+\&
+    for (size_t i = 0; i < 64; i++) {
+        key[i] = rand() & 1;
+    }
+\&
+    for (size_t i = 0; i < 8; i++) {
+        for (size_t j = 0; j < 8; j++) {
+            buf[i * 8 + j] = orig[i] >> j & 1;
+        }
+        setkey(key);
+    }
+    printf("Before encrypting: %s\en", orig);
+\&
+    encrypt(buf, 0);
+    for (size_t i = 0; i < 8; i++) {
+        for (size_t j = 0, txt[i] = \[aq]\e0\[aq]; j < 8; j++) {
+            txt[i] |= buf[i * 8 + j] << j;
+        }
+        txt[8] = \[aq]\e0\[aq];
+    }
+    printf("After encrypting:  %s\en", txt);
+\&
+    encrypt(buf, 1);
+    for (size_t i = 0; i < 8; i++) {
+        for (size_t j = 0, txt[i] = \[aq]\e0\[aq]; j < 8; j++) {
+            txt[i] |= buf[i * 8 + j] << j;
+        }
+        txt[8] = \[aq]\e0\[aq];
+    }
+    printf("After decrypting:  %s\en", txt);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR cbc_crypt (3),
+.BR crypt (3),
+.BR ecb_crypt (3)
+.\" .BR fcrypt (3)
diff --git a/man/man3/encrypt_r.3 b/man/man3/encrypt_r.3
new file mode 100644
index 000000000..e34c9e911
--- /dev/null
+++ b/man/man3/encrypt_r.3
@@ -0,0 +1 @@
+.so man3/encrypt.3
diff --git a/man/man3/end.3 b/man/man3/end.3
new file mode 100644
index 000000000..f0c22ff5d
--- /dev/null
+++ b/man/man3/end.3
@@ -0,0 +1,96 @@
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH end 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+etext, edata, end \- end of program segments
+.SH SYNOPSIS
+.nf
+.BI extern " etext" ;
+.BI extern " edata" ;
+.BI extern " end" ;
+.fi
+.SH DESCRIPTION
+The addresses of these symbols indicate the end of various program
+segments:
+.TP
+.I etext
+This is the first address past the end of the text segment
+(the program code).
+.TP
+.I edata
+This is the first address past the end of the
+initialized data segment.
+.TP
+.I end
+This is the first address past the end of the
+uninitialized data segment (also known as the BSS segment).
+.SH STANDARDS
+None.
+.SH HISTORY
+Although these symbols have long been provided on most UNIX systems,
+they are not standardized; use with caution.
+.SH NOTES
+The program must explicitly declare these symbols;
+they are not defined in any header file.
+.P
+On some systems the names of these symbols are preceded by underscores,
+thus:
+.IR _etext ,
+.IR _edata ,
+and
+.IR _end .
+These symbols are also defined for programs compiled on Linux.
+.P
+At the start of program execution,
+the program break will be somewhere near
+.I &end
+(perhaps at the start of the following page).
+However, the break will change as memory is allocated via
+.BR brk (2)
+or
+.BR malloc (3).
+Use
+.BR sbrk (2)
+with an argument of zero to find the current value of the program break.
+.SH EXAMPLES
+When run, the program below produces output such as the following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+First address past:
+    program text (etext)       0x8048568
+    initialized data (edata)   0x804a01c
+    uninitialized data (end)   0x804a024
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (end.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+\&
+extern char etext, edata, end; /* The symbols must have some type,
+                                   or "gcc \-Wall" complains */
+\&
+int
+main(void)
+{
+    printf("First address past:\en");
+    printf("    program text (etext)      %10p\en", &etext);
+    printf("    initialized data (edata)  %10p\en", &edata);
+    printf("    uninitialized data (end)  %10p\en", &end);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR objdump (1),
+.BR readelf (1),
+.BR sbrk (2),
+.BR elf (5)
diff --git a/man/man3/endaliasent.3 b/man/man3/endaliasent.3
new file mode 100644
index 000000000..37dcf1914
--- /dev/null
+++ b/man/man3/endaliasent.3
@@ -0,0 +1 @@
+.so man3/setaliasent.3
diff --git a/man/man3/endfsent.3 b/man/man3/endfsent.3
new file mode 100644
index 000000000..1e6a3eb7e
--- /dev/null
+++ b/man/man3/endfsent.3
@@ -0,0 +1 @@
+.so man3/getfsent.3
diff --git a/man/man3/endgrent.3 b/man/man3/endgrent.3
new file mode 100644
index 000000000..bde736fff
--- /dev/null
+++ b/man/man3/endgrent.3
@@ -0,0 +1 @@
+.so man3/getgrent.3
diff --git a/man/man3/endhostent.3 b/man/man3/endhostent.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/endhostent.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/endian.3 b/man/man3/endian.3
new file mode 100644
index 000000000..6cd85317a
--- /dev/null
+++ b/man/man3/endian.3
@@ -0,0 +1,164 @@
+.\" Copyright (C) 2009, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\" a few pieces remain from an earlier version
+.\" Copyright (C) 2008, Nanno Langstraat <nal@ii.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH endian 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+htobe16, htole16, be16toh, le16toh, htobe32, htole32, be32toh, le32toh,
+htobe64, htole64, be64toh, le64toh \-
+convert values between host and big-/little-endian byte order
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <endian.h>
+.P
+.BI "uint16_t htobe16(uint16_t " host_16bits );
+.BI "uint16_t htole16(uint16_t " host_16bits );
+.BI "uint16_t be16toh(uint16_t " big_endian_16bits );
+.BI "uint16_t le16toh(uint16_t " little_endian_16bits );
+.P
+.BI "uint32_t htobe32(uint32_t " host_32bits );
+.BI "uint32_t htole32(uint32_t " host_32bits );
+.BI "uint32_t be32toh(uint32_t " big_endian_32bits );
+.BI "uint32_t le32toh(uint32_t " little_endian_32bits );
+.P
+.BI "uint64_t htobe64(uint64_t " host_64bits );
+.BI "uint64_t htole64(uint64_t " host_64bits );
+.BI "uint64_t be64toh(uint64_t " big_endian_64bits );
+.BI "uint64_t le64toh(uint64_t " little_endian_64bits );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.ad l
+.P
+.BR htobe16 (),
+.BR htole16 (),
+.BR be16toh (),
+.BR le16toh (),
+.BR htobe32 (),
+.BR htole32 (),
+.BR be32toh (),
+.BR le32toh (),
+.BR htobe64 (),
+.BR htole64 (),
+.BR be64toh (),
+.BR le64toh ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    In glibc up to and including 2.19:
+        _BSD_SOURCE
+.fi
+.ad
+.SH DESCRIPTION
+These functions convert the byte encoding of integer values from
+the byte order that the current CPU (the "host") uses,
+to and from little-endian and big-endian byte order.
+.P
+The number,
+.IR nn ,
+in the name of each function indicates the size of
+integer handled by the function, either 16, 32, or 64 bits.
+.P
+The functions with names of the form "htobe\fInn\fP" convert
+from host byte order to big-endian order.
+.P
+The functions with names of the form "htole\fInn\fP" convert
+from host byte order to little-endian order.
+.P
+The functions with names of the form "be\fInn\fPtoh" convert
+from big-endian order to host byte order.
+.P
+The functions with names of the form "le\fInn\fPtoh" convert
+from little-endian order to host byte order.
+.SH VERSIONS
+Similar functions are present on the BSDs,
+where the required header file is
+.I <sys/endian.h>
+instead of
+.IR <endian.h> .
+Unfortunately,
+NetBSD, FreeBSD, and glibc haven't followed the original
+OpenBSD naming convention for these functions,
+whereby the
+.I nn
+component always appears at the end of the function name
+(thus, for example, in NetBSD, FreeBSD, and glibc,
+the equivalent of OpenBSDs "betoh32" is "be32toh").
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.9.
+.P
+These functions are similar to the older
+.BR byteorder (3)
+family of functions.
+For example,
+.BR be32toh ()
+is identical to
+.BR ntohl ().
+.P
+The advantage of the
+.BR byteorder (3)
+functions is that they are standard functions available
+on all UNIX systems.
+On the other hand, the fact that they were designed
+for use in the context of TCP/IP means that
+they lack the 64-bit and little-endian variants described in this page.
+.SH EXAMPLES
+The program below display the results of converting an integer
+from host byte order to both little-endian and big-endian byte order.
+Since host byte order is either little-endian or big-endian,
+only one of these conversions will have an effect.
+When we run this program on a little-endian system such as x86-32,
+we see the following:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+x.u32 = 0x44332211
+htole32(x.u32) = 0x44332211
+htobe32(x.u32) = 0x11223344
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (endian.c)
+.EX
+#include <endian.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    union {
+        uint32_t u32;
+        uint8_t arr[4];
+    } x;
+\&
+    x.arr[0] = 0x11;	/* Lowest\-address byte */
+    x.arr[1] = 0x22;
+    x.arr[2] = 0x33;
+    x.arr[3] = 0x44;	/* Highest\-address byte */
+\&
+    printf("x.u32 = %#x\en", x.u32);
+    printf("htole32(x.u32) = %#x\en", htole32(x.u32));
+    printf("htobe32(x.u32) = %#x\en", htobe32(x.u32));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR bswap (3),
+.BR byteorder (3)
diff --git a/man/man3/endmntent.3 b/man/man3/endmntent.3
new file mode 100644
index 000000000..3c2bb35c9
--- /dev/null
+++ b/man/man3/endmntent.3
@@ -0,0 +1 @@
+.so man3/getmntent.3
diff --git a/man/man3/endnetent.3 b/man/man3/endnetent.3
new file mode 100644
index 000000000..70f5670dc
--- /dev/null
+++ b/man/man3/endnetent.3
@@ -0,0 +1 @@
+.so man3/getnetent.3
diff --git a/man/man3/endnetgrent.3 b/man/man3/endnetgrent.3
new file mode 100644
index 000000000..34268f941
--- /dev/null
+++ b/man/man3/endnetgrent.3
@@ -0,0 +1 @@
+.so man3/setnetgrent.3
diff --git a/man/man3/endprotoent.3 b/man/man3/endprotoent.3
new file mode 100644
index 000000000..f8cb4bba2
--- /dev/null
+++ b/man/man3/endprotoent.3
@@ -0,0 +1 @@
+.so man3/getprotoent.3
diff --git a/man/man3/endpwent.3 b/man/man3/endpwent.3
new file mode 100644
index 000000000..f2d121b80
--- /dev/null
+++ b/man/man3/endpwent.3
@@ -0,0 +1 @@
+.so man3/getpwent.3
diff --git a/man/man3/endrpcent.3 b/man/man3/endrpcent.3
new file mode 100644
index 000000000..923085e2e
--- /dev/null
+++ b/man/man3/endrpcent.3
@@ -0,0 +1 @@
+.so man3/getrpcent.3
diff --git a/man/man3/endservent.3 b/man/man3/endservent.3
new file mode 100644
index 000000000..eaafb1c1e
--- /dev/null
+++ b/man/man3/endservent.3
@@ -0,0 +1 @@
+.so man3/getservent.3
diff --git a/man/man3/endspent.3 b/man/man3/endspent.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/endspent.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/endttyent.3 b/man/man3/endttyent.3
new file mode 100644
index 000000000..1cd11e3d8
--- /dev/null
+++ b/man/man3/endttyent.3
@@ -0,0 +1 @@
+.so man3/getttyent.3
diff --git a/man/man3/endusershell.3 b/man/man3/endusershell.3
new file mode 100644
index 000000000..718ed12e9
--- /dev/null
+++ b/man/man3/endusershell.3
@@ -0,0 +1 @@
+.so man3/getusershell.3
diff --git a/man/man3/endutent.3 b/man/man3/endutent.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/endutent.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/endutxent.3 b/man/man3/endutxent.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/endutxent.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/envz.3 b/man/man3/envz.3
new file mode 100644
index 000000000..12e0737e2
--- /dev/null
+++ b/man/man3/envz.3
@@ -0,0 +1 @@
+.so man3/envz_add.3
diff --git a/man/man3/envz_add.3 b/man/man3/envz_add.3
new file mode 100644
index 000000000..fd5b77029
--- /dev/null
+++ b/man/man3/envz_add.3
@@ -0,0 +1,168 @@
+'\" t
+.\" Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" based on the description in glibc source and infopages
+.\"
+.\" Corrections and additions, aeb
+.TH envz_add 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+envz_add, envz_entry, envz_get, envz_merge,
+envz_remove, envz_strip \- environment string support
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <envz.h>
+.P
+.BI "error_t envz_add(char **restrict " envz ", size_t *restrict " envz_len ,
+.BI "               const char *restrict " name \
+", const char *restrict " value );
+.P
+.BI "char *envz_entry(const char *restrict " envz ", size_t " envz_len ,
+.BI "               const char *restrict " name );
+.P
+.BI "char *envz_get(const char *restrict " envz ", size_t " envz_len ,
+.BI "               const char *restrict " name );
+.P
+.BI "error_t envz_merge(char **restrict " envz ", size_t *restrict " envz_len ,
+.BI "               const char *restrict " envz2 ", size_t " envz2_len ,
+.BI "               int " override );
+.P
+.BI "void envz_remove(char **restrict " envz ", size_t *restrict " envz_len ,
+.BI "               const char *restrict " name );
+.P
+.BI "void envz_strip(char **restrict " envz ", size_t *restrict " envz_len );
+.fi
+.SH DESCRIPTION
+These functions are glibc-specific.
+.P
+An argz vector is a pointer to a character buffer together with a length,
+see
+.BR argz_add (3).
+An envz vector is a special argz vector, namely one where the strings
+have the form "name=value".
+Everything after the first \[aq]=\[aq] is considered
+to be the value.
+If there is no \[aq]=\[aq], the value is taken to be NULL.
+(While the value in case of a trailing \[aq]=\[aq] is the empty string "".)
+.P
+These functions are for handling envz vectors.
+.P
+.BR envz_add ()
+adds the string
+.RI \&" name = value \&"
+(in case
+.I value
+is non-NULL) or
+.RI \&" name \&"
+(in case
+.I value
+is NULL) to the envz vector
+.RI ( *envz ,\  *envz_len )
+and updates
+.I *envz
+and
+.IR *envz_len .
+If an entry with the same
+.I name
+existed, it is removed.
+.P
+.BR envz_entry ()
+looks for
+.I name
+in the envz vector
+.RI ( envz ,\  envz_len )
+and returns the entry if found, or NULL if not.
+.P
+.BR envz_get ()
+looks for
+.I name
+in the envz vector
+.RI ( envz ,\  envz_len )
+and returns the value if found, or NULL if not.
+(Note that the value can also be NULL, namely when there is
+an entry for
+.I name
+without \[aq]=\[aq] sign.)
+.P
+.BR envz_merge ()
+adds each entry in
+.I envz2
+to
+.IR *envz ,
+as if with
+.BR envz_add ().
+If
+.I override
+is true, then values in
+.I envz2
+will supersede those with the same name in
+.IR *envz ,
+otherwise not.
+.P
+.BR envz_remove ()
+removes the entry for
+.I name
+from
+.RI ( *envz ,\  *envz_len )
+if there was one.
+.P
+.BR envz_strip ()
+removes all entries with value NULL.
+.SH RETURN VALUE
+All envz functions that do memory allocation have a return type of
+.I error_t
+(an integer type),
+and return 0 for success, and
+.B ENOMEM
+if an allocation error occurs.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR envz_add (),
+.BR envz_entry (),
+.BR envz_get (),
+.BR envz_merge (),
+.BR envz_remove (),
+.BR envz_strip ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH EXAMPLES
+.\" SRC BEGIN (envz_add.c)
+.EX
+#include <envz.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[], char *envp[])
+{
+    char    *str;
+    size_t  e_len = 0;
+\&
+    for (size_t i = 0; envp[i] != NULL; i++)
+        e_len += strlen(envp[i]) + 1;
+\&
+    str = envz_entry(*envp, e_len, "HOME");
+    printf("%s\en", str);
+    str = envz_get(*envp, e_len, "HOME");
+    printf("%s\en", str);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR argz_add (3)
diff --git a/man/man3/envz_entry.3 b/man/man3/envz_entry.3
new file mode 100644
index 000000000..12e0737e2
--- /dev/null
+++ b/man/man3/envz_entry.3
@@ -0,0 +1 @@
+.so man3/envz_add.3
diff --git a/man/man3/envz_get.3 b/man/man3/envz_get.3
new file mode 100644
index 000000000..12e0737e2
--- /dev/null
+++ b/man/man3/envz_get.3
@@ -0,0 +1 @@
+.so man3/envz_add.3
diff --git a/man/man3/envz_merge.3 b/man/man3/envz_merge.3
new file mode 100644
index 000000000..12e0737e2
--- /dev/null
+++ b/man/man3/envz_merge.3
@@ -0,0 +1 @@
+.so man3/envz_add.3
diff --git a/man/man3/envz_remove.3 b/man/man3/envz_remove.3
new file mode 100644
index 000000000..12e0737e2
--- /dev/null
+++ b/man/man3/envz_remove.3
@@ -0,0 +1 @@
+.so man3/envz_add.3
diff --git a/man/man3/envz_strip.3 b/man/man3/envz_strip.3
new file mode 100644
index 000000000..12e0737e2
--- /dev/null
+++ b/man/man3/envz_strip.3
@@ -0,0 +1 @@
+.so man3/envz_add.3
diff --git a/man/man3/erand48.3 b/man/man3/erand48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/erand48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/erand48_r.3 b/man/man3/erand48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/erand48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/erf.3 b/man/man3/erf.3
new file mode 100644
index 000000000..b43b866e5
--- /dev/null
+++ b/man/man3/erf.3
@@ -0,0 +1,131 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH erf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+erf, erff, erfl \- error function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double erf(double " x );
+.BI "float erff(float " x );
+.BI "long double erfl(long double " x );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR erf ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR erff (),
+.BR erfl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the error function of
+.IR x ,
+defined as
+.P
+.in +4n
+.EX
+erf(x) = 2/sqrt(pi) * integral from 0 to x of exp(\-t*t) dt
+.EE
+.in
+.SH RETURN VALUE
+On success, these functions return the value of the error function of
+.IR x ,
+a value in the range [\-1,\ 1].
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0), +0 (\-0) is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity),
++1 (\-1) is returned.
+.P
+If
+.I x
+is subnormal,
+a range error occurs,
+and the return value is 2*x/sqrt(pi).
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result underflow (\fIx\fP is subnormal)
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.P
+These functions do not set
+.IR errno .
+.\" It is intentional that these functions do not set errno for this case
+.\" see https://www.sourceware.org/bugzilla/show_bug.cgi?id=6785
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR erf (),
+.BR erff (),
+.BR erfl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR cerf (3),
+.BR erfc (3),
+.BR exp (3)
diff --git a/man/man3/erfc.3 b/man/man3/erfc.3
new file mode 100644
index 000000000..f5717c789
--- /dev/null
+++ b/man/man3/erfc.3
@@ -0,0 +1,134 @@
+'\" t
+.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH erfc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+erfc, erfcf, erfcl \- complementary error function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double erfc(double " x );
+.BI "float erfcf(float " x );
+.BI "long double erfcl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR erfc ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR erfcf (),
+.BR erfcl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the complementary error function of
+.IR x ,
+that is, 1.0 \- erf(x).
+.SH RETURN VALUE
+On success, these functions return the complementary error function of
+.IR x ,
+a value in the range [0,2].
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 or \-0, 1 is returned.
+.P
+If
+.I x
+is positive infinity,
++0 is returned.
+.P
+If
+.I x
+is negative infinity,
++2 is returned.
+.P
+If the function result underflows and produces an unrepresentable value,
+the return value is 0.0.
+.P
+If the function result underflows but produces a representable
+(i.e., subnormal) value,
+.\" e.g., erfc(27) on x86-32
+that value is returned, and
+a range error occurs.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result underflow (result is subnormal)
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.P
+These functions do not set
+.IR errno .
+.\" It is intentional that these functions do not set errno for this case
+.\" see https://www.sourceware.org/bugzilla/show_bug.cgi?id=6785
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR erfc (),
+.BR erfcf (),
+.BR erfcl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH NOTES
+The
+.BR erfc (),
+.BR erfcf (),
+and
+.BR erfcl ()
+functions are provided to avoid the loss accuracy that
+would occur for the calculation 1-erf(x) for large values of
+.I x
+(for which the value of erf(x) approaches 1).
+.SH SEE ALSO
+.BR cerf (3),
+.BR erf (3),
+.BR exp (3)
diff --git a/man/man3/erfcf.3 b/man/man3/erfcf.3
new file mode 100644
index 000000000..371bd6b5c
--- /dev/null
+++ b/man/man3/erfcf.3
@@ -0,0 +1 @@
+.so man3/erfc.3
diff --git a/man/man3/erfcl.3 b/man/man3/erfcl.3
new file mode 100644
index 000000000..371bd6b5c
--- /dev/null
+++ b/man/man3/erfcl.3
@@ -0,0 +1 @@
+.so man3/erfc.3
diff --git a/man/man3/erff.3 b/man/man3/erff.3
new file mode 100644
index 000000000..fc5471fcb
--- /dev/null
+++ b/man/man3/erff.3
@@ -0,0 +1 @@
+.so man3/erf.3
diff --git a/man/man3/erfl.3 b/man/man3/erfl.3
new file mode 100644
index 000000000..fc5471fcb
--- /dev/null
+++ b/man/man3/erfl.3
@@ -0,0 +1 @@
+.so man3/erf.3
diff --git a/man/man3/err.3 b/man/man3/err.3
new file mode 100644
index 000000000..7df6d6cfe
--- /dev/null
+++ b/man/man3/err.3
@@ -0,0 +1,154 @@
+'\" t
+.\" Copyright (c) 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	From: @(#)err.3	8.1 (Berkeley) 6/9/93
+.\" $FreeBSD: src/lib/libc/gen/err.3,v 1.11.2.5 2001/08/17 15:42:32 ru Exp $
+.\"
+.\" 2011-09-10, mtk, Converted from mdoc to man macros
+.\"
+.TH err 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+err, verr, errx, verrx, warn, vwarn, warnx, vwarnx \- formatted error messages
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <err.h>
+.P
+.BI "[[noreturn]] void err(int " eval ", const char *" fmt ", ...);"
+.BI "[[noreturn]] void errx(int " eval ", const char *" fmt ", ...);"
+.P
+.BI "void warn(const char *" fmt ", ...);"
+.BI "void warnx(const char *" fmt ", ...);"
+.P
+.B #include <stdarg.h>
+.P
+.BI "[[noreturn]] void verr(int " eval ", const char *" fmt ", va_list " args );
+.BI "[[noreturn]] void verrx(int " eval ", const char *" fmt ", va_list " args );
+.P
+.BI "void vwarn(const char *" fmt ", va_list " args );
+.BI "void vwarnx(const char *" fmt ", va_list " args );
+.fi
+.SH DESCRIPTION
+The
+.BR err ()
+and
+.BR warn ()
+family of functions display a formatted error message on the standard
+error output.
+In all cases, the last component of the program name, a colon character,
+and a space are output.
+If the
+.I fmt
+argument is not NULL, the
+.BR printf (3)-like
+formatted error message is output.
+The output is terminated by a newline character.
+.P
+The
+.BR err (),
+.BR verr (),
+.BR warn (),
+and
+.BR vwarn ()
+functions append an error message obtained from
+.BR strerror (3)
+based on the global variable
+.IR errno ,
+preceded by another colon and space unless the
+.I fmt
+argument is
+NULL.
+.P
+The
+.BR errx ()
+and
+.BR warnx ()
+functions do not append an error message.
+.P
+The
+.BR err (),
+.BR verr (),
+.BR errx (),
+and
+.BR verrx ()
+functions do not return, but exit with the value of the argument
+.IR eval .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR err (),
+.BR errx (),
+.BR warn (),
+.BR warnx (),
+.BR verr (),
+.BR verrx (),
+.BR vwarn (),
+.BR vwarnx ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+.TP
+.BR err ()
+.TQ
+.BR warn ()
+4.4BSD.
+.SH EXAMPLES
+Display the current
+.I errno
+information string and exit:
+.P
+.in +4n
+.EX
+p = malloc(size);
+if (p == NULL)
+    err(EXIT_FAILURE, NULL);
+fd = open(file_name, O_RDONLY, 0);
+if (fd == \-1)
+    err(EXIT_FAILURE, "%s", file_name);
+.EE
+.in
+.P
+Display an error message and exit:
+.P
+.in +4n
+.EX
+if (tm.tm_hour < START_TIME)
+    errx(EXIT_FAILURE, "too early, wait until %s",
+            start_time_string);
+.EE
+.in
+.P
+Warn of an error:
+.P
+.in +4n
+.EX
+fd = open(raw_device, O_RDONLY, 0);
+if (fd == \-1)
+    warnx("%s: %s: trying the block device",
+            raw_device, strerror(errno));
+fd = open(block_device, O_RDONLY, 0);
+if (fd == \-1)
+    err(EXIT_FAILURE, "%s", block_device);
+.EE
+.in
+.SH SEE ALSO
+.BR error (3),
+.BR exit (3),
+.BR perror (3),
+.BR printf (3),
+.BR strerror (3)
diff --git a/man/man3/errno.3 b/man/man3/errno.3
new file mode 100644
index 000000000..786dec824
--- /dev/null
+++ b/man/man3/errno.3
@@ -0,0 +1,655 @@
+.\" Copyright (c) 1996 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 5 Oct 2002, Modified by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 	Updated for POSIX.1 2001
+.\" 2004-12-17 Martin Schulze <joey@infodrom.org>, mtk
+.\"	Removed errno declaration prototype, added notes
+.\" 2006-02-09 Kurt Wall, mtk
+.\"     Added non-POSIX errors
+.\"
+.TH errno 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+errno \- number of last error
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <errno.h>
+.\".P
+.\".BI "extern int " errno ;
+.fi
+.SH DESCRIPTION
+The
+.I <errno.h>
+header file defines the integer variable
+.IR errno ,
+which is set by system calls and some library functions in the event
+of an error to indicate what went wrong.
+.\"
+.SS errno
+The value in
+.I errno
+is significant only when the return value of
+the call indicated an error
+(i.e., \-1 from most system calls;
+\-1 or NULL from most library functions);
+a function that succeeds
+.I is
+allowed to change
+.IR errno .
+The value of
+.I errno
+is never set to zero by any system call or library function.
+.P
+For some system calls and library functions (e.g.,
+.BR getpriority (2)),
+\-1 is a valid return on success.
+In such cases, a successful return can be distinguished from an error
+return by setting
+.I errno
+to zero before the call, and then,
+if the call returns a status that indicates that an error
+may have occurred, checking to see if
+.I errno
+has a nonzero value.
+.P
+.I errno
+is defined by the ISO C standard to be a modifiable lvalue
+of type
+.IR int ,
+and must not be explicitly declared;
+.I errno
+may be a macro.
+.I errno
+is thread-local; setting it in one thread
+does not affect its value in any other thread.
+.\"
+.SS Error numbers and names
+Valid error numbers are all positive numbers.
+The
+.I <errno.h>
+header file defines symbolic names for each
+of the possible error numbers that may appear in
+.IR errno .
+.P
+All the error names specified by POSIX.1
+must have distinct values, with the exception of
+.B EAGAIN
+and
+.BR EWOULDBLOCK ,
+which may be the same.
+On Linux, these two have the same value on all architectures.
+.P
+The error numbers that correspond to each symbolic name
+vary across UNIX systems,
+and even across different architectures on Linux.
+Therefore, numeric values are not included as part of the list of
+error names below.
+The
+.BR perror (3)
+and
+.BR strerror (3)
+functions can be used to convert these names to
+corresponding textual error messages.
+.P
+On any particular Linux system,
+one can obtain a list of all symbolic error names and
+the corresponding error numbers using the
+.BR errno (1)
+command (part of the
+.I moreutils
+package):
+.P
+.in +4n
+.EX
+$ \fBerrno \-l\fP
+EPERM 1 Operation not permitted
+ENOENT 2 No such file or directory
+ESRCH 3 No such process
+EINTR 4 Interrupted system call
+EIO 5 Input/output error
+\&...
+.EE
+.in
+.P
+The
+.BR errno (1)
+command can also be used to look up individual error numbers and names,
+and to search for errors using strings from the error description,
+as in the following examples:
+.P
+.in +4n
+.EX
+$ \fBerrno 2\fP
+ENOENT 2 No such file or directory
+$ \fBerrno ESRCH\fP
+ESRCH 3 No such process
+$ \fBerrno \-s permission\fP
+EACCES 13 Permission denied
+.EE
+.in
+.\".P
+.\" POSIX.1 (2001 edition) lists the following symbolic error names.  Of
+.\" these, \fBEDOM\fP and \fBERANGE\fP are in the ISO C standard.  ISO C
+.\" Amendment 1 defines the additional error number \fBEILSEQ\fP for
+.\" coding errors in multibyte or wide characters.
+.\"
+.SS List of error names
+In the list of the symbolic error names below,
+various names are marked as follows:
+.TP
+.I POSIX.1-2001
+The name is defined by POSIX.1-2001,
+and is defined in later POSIX.1 versions, unless otherwise indicated.
+.TP
+.I POSIX.1-2008
+The name is defined in POSIX.1-2008,
+but was not present in earlier POSIX.1 standards.
+.TP
+.I C99
+The name is defined by C99.
+.P
+Below is a list of the symbolic error names that are defined on Linux:
+.TP 16
+.B E2BIG
+Argument list too long (POSIX.1-2001).
+.TP
+.B EACCES
+Permission denied (POSIX.1-2001).
+.TP
+.B EADDRINUSE
+Address already in use (POSIX.1-2001).
+.TP
+.B EADDRNOTAVAIL
+Address not available (POSIX.1-2001).
+.\" EADV is only an error on HURD(?)
+.TP
+.B EAFNOSUPPORT
+Address family not supported (POSIX.1-2001).
+.TP
+.B EAGAIN
+Resource temporarily unavailable (may be the same value as
+.BR EWOULDBLOCK )
+(POSIX.1-2001).
+.TP
+.B EALREADY
+Connection already in progress (POSIX.1-2001).
+.TP
+.B EBADE
+Invalid exchange.
+.TP
+.B EBADF
+Bad file descriptor (POSIX.1-2001).
+.TP
+.B EBADFD
+File descriptor in bad state.
+.TP
+.B EBADMSG
+Bad message (POSIX.1-2001).
+.TP
+.B EBADR
+Invalid request descriptor.
+.TP
+.B EBADRQC
+Invalid request code.
+.TP
+.B EBADSLT
+Invalid slot.
+.\" EBFONT is defined but appears not to be used by kernel or glibc.
+.TP
+.B EBUSY
+Device or resource busy (POSIX.1-2001).
+.TP
+.B ECANCELED
+Operation canceled (POSIX.1-2001).
+.TP
+.B ECHILD
+No child processes (POSIX.1-2001).
+.TP
+.B ECHRNG
+Channel number out of range.
+.TP
+.B ECOMM
+Communication error on send.
+.TP
+.B ECONNABORTED
+Connection aborted (POSIX.1-2001).
+.TP
+.B ECONNREFUSED
+Connection refused (POSIX.1-2001).
+.TP
+.B ECONNRESET
+Connection reset (POSIX.1-2001).
+.TP
+.B EDEADLK
+Resource deadlock avoided (POSIX.1-2001).
+.TP
+.B EDEADLOCK
+On most architectures, a synonym for
+.BR EDEADLK .
+On some architectures (e.g., Linux MIPS, PowerPC, SPARC),
+it is a separate error code "File locking deadlock error".
+.TP
+.B EDESTADDRREQ
+Destination address required (POSIX.1-2001).
+.TP
+.B EDOM
+Mathematics argument out of domain of function (POSIX.1, C99).
+.\" EDOTDOT is defined but appears to be unused
+.TP
+.B EDQUOT
+.\" POSIX just says "Reserved"
+Disk quota exceeded (POSIX.1-2001).
+.TP
+.B EEXIST
+File exists (POSIX.1-2001).
+.TP
+.B EFAULT
+Bad address (POSIX.1-2001).
+.TP
+.B EFBIG
+File too large (POSIX.1-2001).
+.TP
+.B EHOSTDOWN
+Host is down.
+.TP
+.B EHOSTUNREACH
+Host is unreachable (POSIX.1-2001).
+.TP
+.B EHWPOISON
+Memory page has hardware error.
+.TP
+.B EIDRM
+Identifier removed (POSIX.1-2001).
+.TP
+.B EILSEQ
+Invalid or incomplete multibyte or wide character (POSIX.1, C99).
+.IP
+The text shown here is the glibc error description;
+in POSIX.1, this error is described as "Illegal byte sequence".
+.TP
+.B EINPROGRESS
+Operation in progress (POSIX.1-2001).
+.TP
+.B EINTR
+Interrupted function call (POSIX.1-2001); see
+.BR signal (7).
+.TP
+.B EINVAL
+Invalid argument (POSIX.1-2001).
+.TP
+.B EIO
+Input/output error (POSIX.1-2001).
+.TP
+.B EISCONN
+Socket is connected (POSIX.1-2001).
+.TP
+.B EISDIR
+Is a directory (POSIX.1-2001).
+.TP
+.B EISNAM
+Is a named type file.
+.TP
+.B EKEYEXPIRED
+Key has expired.
+.TP
+.B EKEYREJECTED
+Key was rejected by service.
+.TP
+.B EKEYREVOKED
+Key has been revoked.
+.TP
+.B EL2HLT
+Level 2 halted.
+.TP
+.B EL2NSYNC
+Level 2 not synchronized.
+.TP
+.B EL3HLT
+Level 3 halted.
+.TP
+.B EL3RST
+Level 3 reset.
+.TP
+.B ELIBACC
+Cannot access a needed shared library.
+.TP
+.B ELIBBAD
+Accessing a corrupted shared library.
+.TP
+.B ELIBMAX
+Attempting to link in too many shared libraries.
+.TP
+.B ELIBSCN
+\&.lib section in a.out corrupted
+.TP
+.B ELIBEXEC
+Cannot exec a shared library directly.
+.TP
+.B ELNRNG
+.\" ELNRNG appears to be used by a few drivers
+Link number out of range.
+.TP
+.B ELOOP
+Too many levels of symbolic links (POSIX.1-2001).
+.TP
+.B EMEDIUMTYPE
+Wrong medium type.
+.TP
+.B EMFILE
+Too many open files (POSIX.1-2001).
+Commonly caused by exceeding the
+.B RLIMIT_NOFILE
+resource limit described in
+.BR getrlimit (2).
+Can also be caused by exceeding the limit specified in
+.IR /proc/sys/fs/nr_open .
+.TP
+.B EMLINK
+Too many links (POSIX.1-2001).
+.TP
+.B EMSGSIZE
+Message too long (POSIX.1-2001).
+.TP
+.B EMULTIHOP
+.\" POSIX says "Reserved"
+Multihop attempted (POSIX.1-2001).
+.TP
+.B ENAMETOOLONG
+Filename too long (POSIX.1-2001).
+.\" ENAVAIL is defined, but appears not to be used
+.TP
+.B ENETDOWN
+Network is down (POSIX.1-2001).
+.TP
+.B ENETRESET
+Connection aborted by network (POSIX.1-2001).
+.TP
+.B ENETUNREACH
+Network unreachable (POSIX.1-2001).
+.TP
+.B ENFILE
+Too many open files in system (POSIX.1-2001).
+On Linux, this is probably a result of encountering the
+.I /proc/sys/fs/file\-max
+limit (see
+.BR proc (5)).
+.TP
+.B ENOANO
+.\" ENOANO appears to be used by a few drivers
+No anode.
+.TP
+.B ENOBUFS
+No buffer space available (POSIX.1 (XSI STREAMS option)).
+.\" ENOCSI is defined but appears to be unused.
+.TP
+.B ENODATA
+The named attribute does not exist,
+or the process has no access to this attribute; see
+.BR xattr (7).
+.IP
+In POSIX.1-2001 (XSI STREAMS option),
+this error was described as
+"No message is available on the STREAM head read queue".
+.TP
+.B ENODEV
+No such device (POSIX.1-2001).
+.TP
+.B ENOENT
+No such file or directory (POSIX.1-2001).
+.IP
+Typically, this error results when a specified pathname does not exist,
+or one of the components in the directory prefix of a pathname does not exist,
+or the specified pathname is a dangling symbolic link.
+.TP
+.B ENOEXEC
+Exec format error (POSIX.1-2001).
+.TP
+.B ENOKEY
+Required key not available.
+.TP
+.B ENOLCK
+No locks available (POSIX.1-2001).
+.TP
+.B ENOLINK
+.\" POSIX says "Reserved"
+Link has been severed (POSIX.1-2001).
+.TP
+.B ENOMEDIUM
+No medium found.
+.TP
+.B ENOMEM
+Not enough space/cannot allocate memory (POSIX.1-2001).
+.TP
+.B ENOMSG
+No message of the desired type (POSIX.1-2001).
+.TP
+.B ENONET
+Machine is not on the network.
+.TP
+.B ENOPKG
+Package not installed.
+.TP
+.B ENOPROTOOPT
+Protocol not available (POSIX.1-2001).
+.TP
+.B ENOSPC
+No space left on device (POSIX.1-2001).
+.TP
+.B ENOSR
+No STREAM resources (POSIX.1 (XSI STREAMS option)).
+.TP
+.B ENOSTR
+Not a STREAM (POSIX.1 (XSI STREAMS option)).
+.TP
+.B ENOSYS
+Function not implemented (POSIX.1-2001).
+.TP
+.B ENOTBLK
+Block device required.
+.TP
+.B ENOTCONN
+The socket is not connected (POSIX.1-2001).
+.TP
+.B ENOTDIR
+Not a directory (POSIX.1-2001).
+.TP
+.B ENOTEMPTY
+Directory not empty (POSIX.1-2001).
+.\" ENOTNAM is defined but appears to be unused.
+.TP
+.B ENOTRECOVERABLE
+State not recoverable (POSIX.1-2008).
+.TP
+.B ENOTSOCK
+Not a socket (POSIX.1-2001).
+.TP
+.B ENOTSUP
+Operation not supported (POSIX.1-2001).
+.TP
+.B ENOTTY
+Inappropriate I/O control operation (POSIX.1-2001).
+.TP
+.B ENOTUNIQ
+Name not unique on network.
+.TP
+.B ENXIO
+No such device or address (POSIX.1-2001).
+.TP
+.B EOPNOTSUPP
+Operation not supported on socket (POSIX.1-2001).
+.IP
+.RB ( ENOTSUP
+and
+.B EOPNOTSUPP
+have the same value on Linux, but
+according to POSIX.1 these error values should be distinct.)
+.TP
+.B EOVERFLOW
+Value too large to be stored in data type (POSIX.1-2001).
+.TP
+.B EOWNERDEAD
+.\" Used at least by the user-space side of rubost mutexes
+Owner died (POSIX.1-2008).
+.TP
+.B EPERM
+Operation not permitted (POSIX.1-2001).
+.TP
+.B EPFNOSUPPORT
+Protocol family not supported.
+.TP
+.B EPIPE
+Broken pipe (POSIX.1-2001).
+.TP
+.B EPROTO
+Protocol error (POSIX.1-2001).
+.TP
+.B EPROTONOSUPPORT
+Protocol not supported (POSIX.1-2001).
+.TP
+.B EPROTOTYPE
+Protocol wrong type for socket (POSIX.1-2001).
+.TP
+.B ERANGE
+Result too large (POSIX.1, C99).
+.TP
+.B EREMCHG
+Remote address changed.
+.TP
+.B EREMOTE
+Object is remote.
+.TP
+.B EREMOTEIO
+Remote I/O error.
+.TP
+.B ERESTART
+Interrupted system call should be restarted.
+.TP
+.B ERFKILL
+.\" ERFKILL appears to be used by various drivers
+Operation not possible due to RF-kill.
+.TP
+.B EROFS
+Read-only filesystem (POSIX.1-2001).
+.TP
+.B ESHUTDOWN
+Cannot send after transport endpoint shutdown.
+.TP
+.B ESPIPE
+Invalid seek (POSIX.1-2001).
+.TP
+.B ESOCKTNOSUPPORT
+Socket type not supported.
+.TP
+.B ESRCH
+No such process (POSIX.1-2001).
+.\" ESRMNT is defined but appears not to be used
+.TP
+.B ESTALE
+Stale file handle (POSIX.1-2001).
+.IP
+This error can occur for NFS and for other filesystems.
+.TP
+.B ESTRPIPE
+Streams pipe error.
+.TP
+.B ETIME
+Timer expired
+(POSIX.1 (XSI STREAMS option)).
+.IP
+(POSIX.1 says "STREAM
+.BR ioctl (2)
+timeout".)
+.TP
+.B ETIMEDOUT
+Connection timed out (POSIX.1-2001).
+.TP
+.B ETOOMANYREFS
+.\" ETOOMANYREFS seems to be used in net/unix/af_unix.c
+Too many references: cannot splice.
+.TP
+.B ETXTBSY
+Text file busy (POSIX.1-2001).
+.TP
+.B EUCLEAN
+Structure needs cleaning.
+.TP
+.B EUNATCH
+Protocol driver not attached.
+.TP
+.B EUSERS
+Too many users.
+.TP
+.B EWOULDBLOCK
+Operation would block (may be same value as
+.BR EAGAIN )
+(POSIX.1-2001).
+.TP
+.B EXDEV
+Invalid cross-device link (POSIX.1-2001).
+.TP
+.B EXFULL
+Exchange full.
+.SH NOTES
+A common mistake is to do
+.P
+.in +4n
+.EX
+if (somecall() == \-1) {
+    printf("somecall() failed\en");
+    if (errno == ...) { ... }
+}
+.EE
+.in
+.P
+where
+.I errno
+no longer needs to have the value it had upon return from
+.IR somecall ()
+(i.e., it may have been changed by the
+.BR printf (3)).
+If the value of
+.I errno
+should be preserved across a library call, it must be saved:
+.P
+.in +4n
+.EX
+if (somecall() == \-1) {
+    int errsv = errno;
+    printf("somecall() failed\en");
+    if (errsv == ...) { ... }
+}
+.EE
+.in
+.P
+Note that the POSIX threads APIs do
+.I not
+set
+.I errno
+on error.
+Instead, on failure they return an error number as the function result.
+These error numbers have the same meanings as the error numbers returned in
+.I errno
+by other APIs.
+.P
+On some ancient systems,
+.I <errno.h>
+was not present or did not declare
+.IR errno ,
+so that it was necessary to declare
+.I errno
+manually
+(i.e.,
+.IR "extern int errno" ).
+.BR "Do not do this" .
+It long ago ceased to be necessary,
+and it will cause problems with modern versions of the C library.
+.SH SEE ALSO
+.BR errno (1),  \" In the moreutils package
+.BR err (3),
+.BR error (3),
+.BR perror (3),
+.BR strerror (3)
diff --git a/man/man3/error.3 b/man/man3/error.3
new file mode 100644
index 000000000..95a964103
--- /dev/null
+++ b/man/man3/error.3
@@ -0,0 +1,171 @@
+'\" t
+.\" Copyright (C) 2006 Justin Pryzby <pryzbyj@justinpryzby.com>
+.\" and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Permission is hereby granted, free of charge, to any person obtaining
+.\" a copy of this software and associated documentation files (the
+.\" "Software"), to deal in the Software without restriction, including
+.\" without limitation the rights to use, copy, modify, merge, publish,
+.\" distribute, sublicense, and/or sell copies of the Software, and to
+.\" permit persons to whom the Software is furnished to do so, subject to
+.\" the following conditions:
+.\"
+.\" The above copyright notice and this permission notice shall be
+.\" included in all copies or substantial portions of the Software.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+.\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+.\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+.\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+.\" %%%LICENSE_END
+.\"
+.\" References:
+.\"   glibc manual and source
+.TH error 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+error, error_at_line, error_message_count, error_one_per_line,
+error_print_progname \- glibc error reporting functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <error.h>
+.P
+.BI "void error(int " status ", int " errnum ", const char *" format ", ...);"
+.BI "void error_at_line(int " status ", int " errnum ", const char *" filename ,
+.BI "                   unsigned int " linenum ", const char *" format ", ...);"
+.P
+.BI "extern unsigned int " error_message_count ;
+.BI "extern int " error_one_per_line ;
+.P
+.BI "extern void (*" error_print_progname ")(void);"
+.fi
+.SH DESCRIPTION
+.BR error ()
+is a general error-reporting function.
+It flushes
+.IR stdout ,
+and then outputs to
+.I stderr
+the program name, a colon and a space, the message specified by the
+.BR printf (3)-style
+format string \fIformat\fP, and, if \fIerrnum\fP is
+nonzero, a second colon and a space followed by the string given by
+.IR strerror(errnum) .
+Any arguments required for
+.I format
+should follow
+.I format
+in the argument list.
+The output is terminated by a newline character.
+.P
+The program name printed by
+.BR error ()
+is the value of the global variable
+.BR program_invocation_name (3).
+.I program_invocation_name
+initially has the same value as
+.IR main ()'s
+.IR argv[0] .
+The value of this variable can be modified to change the output of
+.BR error ().
+.P
+If \fIstatus\fP has a nonzero value, then
+.BR error ()
+calls
+.BR exit (3)
+to terminate the program using the given value as the exit status;
+otherwise it returns after printing the error message.
+.P
+The
+.BR error_at_line ()
+function is exactly the same as
+.BR error (),
+except for the addition of the arguments
+.I filename
+and
+.IR linenum .
+The output produced is as for
+.BR error (),
+except that after the program name are written: a colon, the value of
+.IR filename ,
+a colon, and the value of
+.IR linenum .
+The preprocessor values \fB__LINE__\fP and
+\fB__FILE__\fP may be useful when calling
+.BR error_at_line (),
+but other values can also be used.
+For example, these arguments could refer to a location in an input file.
+.P
+If the global variable \fIerror_one_per_line\fP is set nonzero,
+a sequence of
+.BR error_at_line ()
+calls with the
+same value of \fIfilename\fP and \fIlinenum\fP will result in only
+one message (the first) being output.
+.P
+The global variable \fIerror_message_count\fP counts the number of
+messages that have been output by
+.BR error ()
+and
+.BR error_at_line ().
+.P
+If the global variable \fIerror_print_progname\fP
+is assigned the address of a function
+(i.e., is not NULL), then that function is called
+instead of prefixing the message with the program name and colon.
+The function should print a suitable string to
+.IR stderr .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR error ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR error_at_line ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe\ race: error_at_line/\:error_one_per_line locale
+T}
+.TE
+.P
+The internal
+.I error_one_per_line
+variable is accessed (without any form of synchronization, but since it's an
+.I int
+used once, it should be safe enough) and, if
+.I error_one_per_line
+is set nonzero, the internal static variables (not exposed to users)
+used to hold the last printed filename and line number are accessed
+and modified without synchronization; the update is not atomic and it
+occurs before disabling cancelation, so it can be interrupted only after
+one of the two variables is modified.
+After that,
+.BR error_at_line ()
+is very much like
+.BR error ().
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR err (3),
+.BR errno (3),
+.BR exit (3),
+.BR perror (3),
+.BR program_invocation_name (3),
+.BR strerror (3)
diff --git a/man/man3/error_at_line.3 b/man/man3/error_at_line.3
new file mode 100644
index 000000000..7ce8691bf
--- /dev/null
+++ b/man/man3/error_at_line.3
@@ -0,0 +1 @@
+.so man3/error.3
diff --git a/man/man3/error_message_count.3 b/man/man3/error_message_count.3
new file mode 100644
index 000000000..7ce8691bf
--- /dev/null
+++ b/man/man3/error_message_count.3
@@ -0,0 +1 @@
+.so man3/error.3
diff --git a/man/man3/error_one_per_line.3 b/man/man3/error_one_per_line.3
new file mode 100644
index 000000000..7ce8691bf
--- /dev/null
+++ b/man/man3/error_one_per_line.3
@@ -0,0 +1 @@
+.so man3/error.3
diff --git a/man/man3/error_print_progname.3 b/man/man3/error_print_progname.3
new file mode 100644
index 000000000..7ce8691bf
--- /dev/null
+++ b/man/man3/error_print_progname.3
@@ -0,0 +1 @@
+.so man3/error.3
diff --git a/man/man3/errx.3 b/man/man3/errx.3
new file mode 100644
index 000000000..3ee2e497a
--- /dev/null
+++ b/man/man3/errx.3
@@ -0,0 +1 @@
+.so man3/err.3
diff --git a/man/man3/etext.3 b/man/man3/etext.3
new file mode 100644
index 000000000..94843fb05
--- /dev/null
+++ b/man/man3/etext.3
@@ -0,0 +1 @@
+.so man3/end.3
diff --git a/man/man3/ether_aton.3 b/man/man3/ether_aton.3
new file mode 100644
index 000000000..7016fcc15
--- /dev/null
+++ b/man/man3/ether_aton.3
@@ -0,0 +1,143 @@
+'\" t
+.\" Copyright 2002 Ian Redfern (redferni@logica.com)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     FreeBSD 4.4 man pages
+.\"
+.\" Minor additions, aeb, 2013-06-21
+.\"
+.TH ether_aton 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ether_aton, ether_ntoa, ether_ntohost, ether_hostton, ether_line,
+ether_ntoa_r, ether_aton_r \- Ethernet address manipulation routines
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netinet/ether.h>
+.P
+.BI "char *ether_ntoa(const struct ether_addr *" addr );
+.BI "struct ether_addr *ether_aton(const char *" asc );
+.P
+.BI "int ether_ntohost(char *" hostname ", const struct ether_addr *" addr );
+.BI "int ether_hostton(const char *" hostname ", struct ether_addr *" addr );
+.P
+.BI "int ether_line(const char *" line ", struct ether_addr *" addr ,
+.BI "               char *" hostname );
+.P
+/* GNU extensions */
+.BI "char *ether_ntoa_r(const struct ether_addr *" addr ", char *" buf );
+.P
+.BI "struct ether_addr *ether_aton_r(const char *" asc ,
+.BI "                                struct ether_addr *" addr );
+.fi
+.SH DESCRIPTION
+.BR ether_aton ()
+converts the 48-bit Ethernet host address
+.I asc
+from the standard hex-digits-and-colons notation into binary data in
+network byte order and returns a pointer to it in a statically
+allocated buffer, which subsequent calls will
+overwrite.
+.BR ether_aton ()
+returns NULL if the address is invalid.
+.P
+The
+.BR ether_ntoa ()
+function converts the Ethernet host address
+.I addr
+given in network byte order to a string in standard
+hex-digits-and-colons notation, omitting leading zeros.
+The string is returned in a statically allocated buffer,
+which subsequent calls will overwrite.
+.P
+The
+.BR ether_ntohost ()
+function maps an Ethernet address to the
+corresponding hostname in
+.I /etc/ethers
+and returns nonzero if it cannot be found.
+.P
+The
+.BR ether_hostton ()
+function maps a hostname to the
+corresponding Ethernet address in
+.I /etc/ethers
+and returns nonzero if it cannot be found.
+.P
+The
+.BR ether_line ()
+function parses a line in
+.I /etc/ethers
+format (ethernet address followed by whitespace followed by
+hostname; \[aq]#\[aq] introduces a comment) and returns an address
+and hostname pair, or nonzero if it cannot be parsed.
+The buffer pointed to by
+.I hostname
+must be sufficiently long, for example, have the same length as
+.IR line .
+.P
+The functions
+.BR ether_ntoa_r ()
+and
+.BR ether_aton_r ()
+are reentrant
+thread-safe versions of
+.BR ether_ntoa ()
+and
+.BR ether_aton ()
+respectively, and do not use static buffers.
+.P
+The structure
+.I ether_addr
+is defined in
+.I <net/ethernet.h>
+as:
+.P
+.in +4n
+.EX
+struct ether_addr {
+    uint8_t ether_addr_octet[6];
+}
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ether_aton (),
+.BR ether_ntoa ()
+T}	Thread safety	MT-Unsafe
+T{
+.na
+.nh
+.BR ether_ntohost (),
+.BR ether_hostton (),
+.BR ether_line (),
+.BR ether_ntoa_r (),
+.BR ether_aton_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD, SunOS.
+.SH BUGS
+In glibc 2.2.5 and earlier, the implementation of
+.BR ether_line ()
+.\" The fix was presumably commit c0a0f9a32c8baa6ab93d00eb42d92c02e9e146d7
+.\" which was in glibc 2.3
+is broken.
+.SH SEE ALSO
+.BR ethers (5)
diff --git a/man/man3/ether_aton_r.3 b/man/man3/ether_aton_r.3
new file mode 100644
index 000000000..f88e044ab
--- /dev/null
+++ b/man/man3/ether_aton_r.3
@@ -0,0 +1 @@
+.so man3/ether_aton.3
diff --git a/man/man3/ether_hostton.3 b/man/man3/ether_hostton.3
new file mode 100644
index 000000000..f88e044ab
--- /dev/null
+++ b/man/man3/ether_hostton.3
@@ -0,0 +1 @@
+.so man3/ether_aton.3
diff --git a/man/man3/ether_line.3 b/man/man3/ether_line.3
new file mode 100644
index 000000000..f88e044ab
--- /dev/null
+++ b/man/man3/ether_line.3
@@ -0,0 +1 @@
+.so man3/ether_aton.3
diff --git a/man/man3/ether_ntoa.3 b/man/man3/ether_ntoa.3
new file mode 100644
index 000000000..f88e044ab
--- /dev/null
+++ b/man/man3/ether_ntoa.3
@@ -0,0 +1 @@
+.so man3/ether_aton.3
diff --git a/man/man3/ether_ntoa_r.3 b/man/man3/ether_ntoa_r.3
new file mode 100644
index 000000000..f88e044ab
--- /dev/null
+++ b/man/man3/ether_ntoa_r.3
@@ -0,0 +1 @@
+.so man3/ether_aton.3
diff --git a/man/man3/ether_ntohost.3 b/man/man3/ether_ntohost.3
new file mode 100644
index 000000000..f88e044ab
--- /dev/null
+++ b/man/man3/ether_ntohost.3
@@ -0,0 +1 @@
+.so man3/ether_aton.3
diff --git a/man/man3/euidaccess.3 b/man/man3/euidaccess.3
new file mode 100644
index 000000000..999bb9d9d
--- /dev/null
+++ b/man/man3/euidaccess.3
@@ -0,0 +1,104 @@
+'\" t
+.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH euidaccess 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+euidaccess, eaccess \- check effective user's permissions for a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BI "int euidaccess(const char *" pathname ", int " mode );
+.BI "int eaccess(const char *" pathname ", int " mode );
+.fi
+.SH DESCRIPTION
+Like
+.BR access (2),
+.BR euidaccess ()
+checks permissions and existence of the file identified by its argument
+.IR pathname .
+However, whereas
+.BR access (2)
+performs checks using the real user and group identifiers of the process,
+.BR euidaccess ()
+uses the effective identifiers.
+.P
+.I mode
+is a mask consisting of one or more of
+.BR R_OK ", " W_OK ", " X_OK ", and " F_OK ,
+with the same meanings as for
+.BR access (2).
+.P
+.BR eaccess ()
+is a synonym for
+.BR euidaccess (),
+provided for compatibility with some other systems.
+.SH RETURN VALUE
+On success (all requested permissions granted), zero is returned.
+On error (at least one bit in
+.I mode
+asked for a permission that is denied, or some other error occurred),
+\-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+As for
+.BR access (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR euidaccess (),
+.BR eaccess ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Some other systems have an
+.\" e.g., FreeBSD 6.1.
+.BR eaccess ()
+function.
+.SH STANDARDS
+None.
+.SH HISTORY
+.TP
+.BR eaccess ()
+glibc 2.4.
+.SH NOTES
+.IR Warning :
+Using this function to check a process's permissions on a file before
+performing some operation based on that information leads to race conditions:
+the file permissions may change between the two steps.
+Generally, it is safer just to attempt the desired operation and handle
+any permission error that occurs.
+.P
+This function always dereferences symbolic links.
+If you need to check the permissions on a symbolic link, use
+.BR faccessat (2)
+with the flags
+.B AT_EACCESS
+and
+.BR AT_SYMLINK_NOFOLLOW .
+.SH SEE ALSO
+.BR access (2),
+.BR chmod (2),
+.BR chown (2),
+.BR faccessat (2),
+.BR open (2),
+.BR setgid (2),
+.BR setuid (2),
+.BR stat (2),
+.BR credentials (7),
+.BR path_resolution (7)
diff --git a/man/man3/eventfd_read.3 b/man/man3/eventfd_read.3
new file mode 100644
index 000000000..eddfaa8a1
--- /dev/null
+++ b/man/man3/eventfd_read.3
@@ -0,0 +1 @@
+.so man2/eventfd.2
diff --git a/man/man3/eventfd_write.3 b/man/man3/eventfd_write.3
new file mode 100644
index 000000000..eddfaa8a1
--- /dev/null
+++ b/man/man3/eventfd_write.3
@@ -0,0 +1 @@
+.so man2/eventfd.2
diff --git a/man/man3/exec.3 b/man/man3/exec.3
new file mode 100644
index 000000000..0ff3b1f48
--- /dev/null
+++ b/man/man3/exec.3
@@ -0,0 +1,311 @@
+'\" t
+.\" Copyright (c) 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)exec.3	6.4 (Berkeley) 4/19/91
+.\"
+.\" Converted for Linux, Mon Nov 29 11:12:48 1993, faith@cs.unc.edu
+.\" Updated more for Linux, Tue Jul 15 11:54:18 1997, pacman@cqc.com
+.\" Modified, 24 Jun 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added note on casting NULL
+.\"
+.TH exec 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+execl, execlp, execle, execv, execvp, execvpe \- execute a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B extern char **environ;
+.P
+.BI "int execl(const char *" pathname ", const char *" arg ", ..."
+.B  "                /*, (char *) NULL */);"
+.BI "int execlp(const char *" file ", const char *" arg ", ..."
+.B  "                /*, (char *) NULL */);"
+.BI "int execle(const char *" pathname ", const char *" arg ", ..."
+.BI "                /*, (char *) NULL, char *const " envp "[] */);"
+.BI "int execv(const char *" pathname ", char *const " argv "[]);"
+.BI "int execvp(const char *" file ", char *const " argv "[]);"
+.BI "int execvpe(const char *" file ", char *const " argv \
+"[], char *const " envp "[]);"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR execvpe ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR exec ()
+family of functions replaces the current process image with a new process
+image.
+The functions described in this manual page are layered on top of
+.BR execve (2).
+(See the manual page for
+.BR execve (2)
+for further details about the replacement of the current process image.)
+.P
+The initial argument for these functions is the name of a file that is
+to be executed.
+.P
+The functions can be grouped based on the letters following the "exec" prefix.
+.\"
+.SS l - execl(), execlp(), execle()
+The
+.I "const char\ *arg"
+and subsequent ellipses can be thought of as
+.IR arg0 ,
+.IR arg1 ,
+\&...,
+.IR argn .
+Together they describe a list of one or more pointers to null-terminated
+strings that represent the argument list available to the executed program.
+The first argument, by convention, should point to the filename associated
+with the file being executed.
+The list of arguments
+.I must
+be terminated by a null pointer,
+and, since these are variadic functions, this pointer must be cast
+.IR "(char\ *) NULL" .
+.P
+By contrast with the 'l' functions, the 'v' functions (below) specify the
+command-line arguments of the executed program as a vector.
+.\"
+.SS v - execv(), execvp(), execvpe()
+The
+.I "char\ *const argv[]"
+argument is an array of pointers to null-terminated strings that
+represent the argument list available to the new program.
+The first argument, by convention, should point to the filename
+associated with the file being executed.
+The array of pointers
+.I must
+be terminated by a null pointer.
+.SS e - execle(), execvpe()
+The environment of the new process image is specified via the argument
+.IR envp .
+The
+.I envp
+argument is an array of pointers to null-terminated strings and
+.I must
+be terminated by a null pointer.
+.P
+All other
+.BR exec ()
+functions (which do not include 'e' in the suffix)
+take the environment for the new process
+image from the external variable
+.I environ
+in the calling process.
+.SS p - execlp(), execvp(), execvpe()
+These functions duplicate the actions of the shell in
+searching for an executable file
+if the specified filename does not contain a slash (/) character.
+The file is sought in the colon-separated list of directory pathnames
+specified in the
+.B PATH
+environment variable.
+If this variable isn't defined, the path list defaults to
+a list that includes the directories returned by
+.I confstr(_CS_PATH)
+(which typically returns the value "/bin:/usr/bin")
+and possibly also the current working directory;
+see NOTES for further details.
+.P
+.BR execvpe ()
+searches for the program using the value of
+.B PATH
+from the caller's environment, not from the
+.I envp
+argument.
+.P
+If the specified filename includes a slash character, then
+.B PATH
+is ignored, and the file at the specified pathname is executed.
+.P
+In addition, certain errors are treated specially.
+.P
+If permission is denied for a file (the attempted
+.BR execve (2)
+failed with the error
+.BR EACCES ),
+these functions will continue searching the rest of the search path.
+If no other file is found, however,
+they will return with
+.I errno
+set to
+.BR EACCES .
+.P
+If the header of a file isn't recognized (the attempted
+.BR execve (2)
+failed with the error
+.BR ENOEXEC ),
+these functions will execute the shell
+.RI ( /bin/sh )
+with the path of the file as its first argument.
+(If this attempt fails, no further searching is done.)
+.P
+All other
+.BR exec ()
+functions (which do not include 'p' in the suffix)
+take as their first argument a (relative or absolute) pathname
+that identifies the program to be executed.
+.SH RETURN VALUE
+The
+.BR exec ()
+functions return only if an error has occurred.
+The return value is \-1, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+All of these functions may fail and set
+.I errno
+for any of the errors specified for
+.BR execve (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR execl (),
+.BR execle (),
+.BR execv ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR execlp (),
+.BR execvp (),
+.BR execvpe ()
+T}	Thread safety	MT-Safe env
+.TE
+.SH VERSIONS
+The default search path (used when the environment
+does not contain the variable \fBPATH\fR)
+shows some variation across systems.
+It generally includes
+.I /bin
+and
+.I /usr/bin
+(in that order) and may also include the current working directory.
+On some other systems, the current working is included after
+.I /bin
+and
+.IR /usr/bin ,
+as an anti-Trojan-horse measure.
+The glibc implementation long followed the traditional default where
+the current working directory is included at the start of the search path.
+However, some code refactoring during the development of glibc 2.24
+.\" glibc commit 1eb8930608705702d5746e5491bab4e4429fcb83
+caused the current working directory to be dropped altogether
+from the default search path.
+This accidental behavior change is considered mildly beneficial,
+and won't be reverted.
+.P
+The behavior of
+.BR execlp ()
+and
+.BR execvp ()
+when errors occur while attempting to execute the file is historic
+practice, but has not traditionally been documented and is not specified by
+the POSIX standard.
+BSD (and possibly other systems) do an automatic
+sleep and retry if
+.B ETXTBSY
+is encountered.
+Linux treats it as a hard
+error and returns immediately.
+.P
+Traditionally, the functions
+.BR execlp ()
+and
+.BR execvp ()
+ignored all errors except for the ones described above and
+.B ENOMEM
+and
+.BR E2BIG ,
+upon which they returned.
+They now return if any error other than the ones
+described above occurs.
+.SH STANDARDS
+.TP
+.B environ
+.TQ
+.BR execl ()
+.TQ
+.BR execlp ()
+.TQ
+.BR execle ()
+.TQ
+.BR execv ()
+.TQ
+.BR execvp ()
+POSIX.1-2008.
+.TP
+.BR execvpe ()
+GNU.
+.SH HISTORY
+.TP
+.B environ
+.TQ
+.BR execl ()
+.TQ
+.BR execlp ()
+.TQ
+.BR execle ()
+.TQ
+.BR execv ()
+.TQ
+.BR execvp ()
+POSIX.1-2001.
+.TP
+.BR execvpe ()
+glibc 2.11.
+.SH BUGS
+Before glibc 2.24,
+.BR execl ()
+and
+.BR execle ()
+employed
+.BR realloc (3)
+internally and were consequently not async-signal-safe,
+in violation of the requirements of POSIX.1.
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=19534
+This was fixed in glibc 2.24.
+.\"
+.SS Architecture-specific details
+On sparc and sparc64,
+.BR execv ()
+is provided as a system call by the kernel
+(with the prototype shown above)
+for compatibility with SunOS.
+This function is
+.I not
+employed by the
+.BR execv ()
+wrapper function on those architectures.
+.SH SEE ALSO
+.BR sh (1),
+.BR execve (2),
+.BR execveat (2),
+.BR fork (2),
+.BR ptrace (2),
+.BR fexecve (3),
+.BR system (3),
+.BR environ (7)
diff --git a/man/man3/execl.3 b/man/man3/execl.3
new file mode 100644
index 000000000..4bf4872a6
--- /dev/null
+++ b/man/man3/execl.3
@@ -0,0 +1 @@
+.so man3/exec.3
diff --git a/man/man3/execle.3 b/man/man3/execle.3
new file mode 100644
index 000000000..4bf4872a6
--- /dev/null
+++ b/man/man3/execle.3
@@ -0,0 +1 @@
+.so man3/exec.3
diff --git a/man/man3/execlp.3 b/man/man3/execlp.3
new file mode 100644
index 000000000..4bf4872a6
--- /dev/null
+++ b/man/man3/execlp.3
@@ -0,0 +1 @@
+.so man3/exec.3
diff --git a/man/man3/execv.3 b/man/man3/execv.3
new file mode 100644
index 000000000..4bf4872a6
--- /dev/null
+++ b/man/man3/execv.3
@@ -0,0 +1 @@
+.so man3/exec.3
diff --git a/man/man3/execvp.3 b/man/man3/execvp.3
new file mode 100644
index 000000000..4bf4872a6
--- /dev/null
+++ b/man/man3/execvp.3
@@ -0,0 +1 @@
+.so man3/exec.3
diff --git a/man/man3/execvpe.3 b/man/man3/execvpe.3
new file mode 100644
index 000000000..4bf4872a6
--- /dev/null
+++ b/man/man3/execvpe.3
@@ -0,0 +1 @@
+.so man3/exec.3
diff --git a/man/man3/exit.3 b/man/man3/exit.3
new file mode 100644
index 000000000..16dad7571
--- /dev/null
+++ b/man/man3/exit.3
@@ -0,0 +1,202 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" FIXME . There are a lot of other process termination actions that
+.\" could be listed on this page. See, for example, the list in the
+.\" POSIX exit(3p) page.
+.\"
+.TH exit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+exit \- cause normal process termination
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "[[noreturn]] void exit(int " status );
+.fi
+.SH DESCRIPTION
+The
+.BR exit ()
+function causes normal process termination and the least significant byte of
+.I status
+(i.e., \fIstatus & 0xFF\fP) is returned to the parent (see
+.BR wait (2)).
+.P
+All functions registered with
+.BR atexit (3)
+and
+.BR on_exit (3)
+are called, in the reverse order of their registration.
+(It is possible for one of these functions to use
+.BR atexit (3)
+or
+.BR on_exit (3)
+to register an additional
+function to be executed during exit processing;
+the new registration is added to the front of the list of functions
+that remain to be called.)
+If one of these functions does not return
+(e.g., it calls
+.BR _exit (2),
+or kills itself with a signal),
+then none of the remaining functions is called,
+and further exit processing (in particular, flushing of
+.BR stdio (3)
+streams) is abandoned.
+If a function has been registered multiple times using
+.BR atexit (3)
+or
+.BR on_exit (3),
+then it is called as many times as it was registered.
+.P
+All open
+.BR stdio (3)
+streams are flushed and closed.
+Files created by
+.BR tmpfile (3)
+are removed.
+.P
+The C standard specifies two constants,
+\fBEXIT_SUCCESS\fP and \fBEXIT_FAILURE\fP,
+that may be passed to
+.BR exit ()
+to indicate successful or unsuccessful
+termination, respectively.
+.SH RETURN VALUE
+The
+.BR exit ()
+function does not return.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR exit ()
+T}	Thread safety	MT-Unsafe race:exit
+.TE
+.P
+The
+.BR exit ()
+function uses a global variable that is not protected,
+so it is not thread-safe.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001, SVr4, 4.3BSD.
+.SH NOTES
+The behavior is undefined if one of the functions registered using
+.BR atexit (3)
+and
+.BR on_exit (3)
+calls either
+.BR exit ()
+or
+.BR longjmp (3).
+Note that a call to
+.BR execve (2)
+removes registrations created using
+.BR atexit (3)
+and
+.BR on_exit (3).
+.P
+The use of
+.B EXIT_SUCCESS
+and
+.B EXIT_FAILURE
+is slightly more portable
+(to non-UNIX environments) than the use of 0 and some nonzero value
+like 1 or \-1.
+In particular, VMS uses a different convention.
+.P
+BSD has attempted to standardize exit codes
+(which some C libraries such as the GNU C library have also adopted);
+see the file
+.IR <sysexits.h> .
+.P
+After
+.BR exit (),
+the exit status must be transmitted to the
+parent process.
+There are three cases:
+.IP \[bu] 3
+If the parent has set
+.BR SA_NOCLDWAIT ,
+or has set the
+.B SIGCHLD
+handler to
+.BR SIG_IGN ,
+the status is discarded and the child dies immediately.
+.IP \[bu]
+If the parent was waiting on the child,
+it is notified of the exit status and the child dies immediately.
+.IP \[bu]
+Otherwise,
+the child becomes a "zombie" process:
+most of the process resources are recycled,
+but a slot containing minimal information about the child process
+(termination status, resource usage statistics) is retained in process table.
+This allows the parent to subsequently use
+.BR waitpid (2)
+(or similar) to learn the termination status of the child;
+at that point the zombie process slot is released.
+.P
+If the implementation supports the
+.B SIGCHLD
+signal, this signal
+is sent to the parent.
+If the parent has set
+.BR SA_NOCLDWAIT ,
+it is undefined whether a
+.B SIGCHLD
+signal is sent.
+.\"
+.SS Signals sent to other processes
+If the exiting process is a session leader and its controlling terminal
+is the controlling terminal of the session, then each process in
+the foreground process group of this controlling terminal
+is sent a
+.B SIGHUP
+signal, and the terminal is disassociated
+from this session, allowing it to be acquired by a new controlling
+process.
+.P
+If the exit of the process causes a process group to become orphaned,
+and if any member of the newly orphaned process group is stopped,
+then a
+.B SIGHUP
+signal followed by a
+.B SIGCONT
+signal will be
+sent to each process in this process group.
+See
+.BR setpgid (2)
+for an explanation of orphaned process groups.
+.P
+Except in the above cases,
+where the signalled processes may be children of the terminating process,
+termination of a process does
+.I not
+in general cause a signal to be sent to children of that process.
+However, a process can use the
+.BR prctl (2)
+.B PR_SET_PDEATHSIG
+operation to arrange that it receives a signal if its parent terminates.
+.SH SEE ALSO
+.BR _exit (2),
+.BR get_robust_list (2),
+.BR setpgid (2),
+.BR wait (2),
+.BR atexit (3),
+.BR on_exit (3),
+.BR tmpfile (3)
diff --git a/man/man3/exp.3 b/man/man3/exp.3
new file mode 100644
index 000000000..378eeb64b
--- /dev/null
+++ b/man/man3/exp.3
@@ -0,0 +1,133 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH exp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+exp, expf, expl \- base-e exponential function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double exp(double " x );
+.BI "float expf(float " x );
+.BI "long double expl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR expf (),
+.BR expl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the value of e (the base of natural
+logarithms) raised to the power of
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the exponential value of
+.IR x .
+.P
+If
+.I x
+is a NaN,
+a NaN is returned.
+.P
+If
+.I x
+is positive infinity,
+positive infinity is returned.
+.P
+If
+.I x
+is negative infinity,
++0 is returned.
+.P
+If the result underflows,
+a range error occurs,
+and zero is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.RB + HUGE_VAL ,
+.RB + HUGE_VALF ,
+or
+.RB + HUGE_VALL ,
+respectively.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error, overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error, underflow
+.I errno
+is set to
+.BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR exp (),
+.BR expf (),
+.BR expl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR cbrt (3),
+.BR cexp (3),
+.BR exp10 (3),
+.BR exp2 (3),
+.BR expm1 (3),
+.BR sqrt (3)
diff --git a/man/man3/exp10.3 b/man/man3/exp10.3
new file mode 100644
index 000000000..d5281fd49
--- /dev/null
+++ b/man/man3/exp10.3
@@ -0,0 +1,82 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.TH exp10 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+exp10, exp10f, exp10l \- base-10 exponential function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <math.h>
+.P
+.BI "double exp10(double " x );
+.BI "float exp10f(float " x );
+.BI "long double exp10l(long double " x );
+.fi
+.SH DESCRIPTION
+These functions return the value of 10
+raised to the power of
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the base-10 exponential value of
+.IR x .
+.P
+For various special cases, including the handling of infinity and NaN,
+as well as overflows and underflows, see
+.BR exp (3).
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+For a discussion of the errors that can occur for these functions, see
+.BR exp (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR exp10 (),
+.BR exp10f (),
+.BR exp10l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.SH BUGS
+Before glibc 2.19, the glibc implementation of these functions did not set
+.I errno
+to
+.B ERANGE
+when an underflow error occurred.
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6787
+.SH SEE ALSO
+.BR cbrt (3),
+.BR exp (3),
+.BR exp2 (3),
+.BR log10 (3),
+.BR sqrt (3)
diff --git a/man/man3/exp10f.3 b/man/man3/exp10f.3
new file mode 100644
index 000000000..705b75e97
--- /dev/null
+++ b/man/man3/exp10f.3
@@ -0,0 +1 @@
+.so man3/exp10.3
diff --git a/man/man3/exp10l.3 b/man/man3/exp10l.3
new file mode 100644
index 000000000..705b75e97
--- /dev/null
+++ b/man/man3/exp10l.3
@@ -0,0 +1 @@
+.so man3/exp10.3
diff --git a/man/man3/exp2.3 b/man/man3/exp2.3
new file mode 100644
index 000000000..fda0b3c3e
--- /dev/null
+++ b/man/man3/exp2.3
@@ -0,0 +1,92 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH exp2 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+exp2, exp2f, exp2l \- base-2 exponential function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double exp2(double " x );
+.BI "float exp2f(float " x );
+.BI "long double exp2l(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR exp2 (),
+.BR exp2f (),
+.BR exp2l ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions return the value of 2 raised to the power of
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the base-2 exponential value of
+.IR x .
+.P
+For various special cases, including the handling of infinity and NaN,
+as well as overflows and underflows, see
+.BR exp (3).
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+For a discussion of the errors that can occur for these functions, see
+.BR exp (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR exp2 (),
+.BR exp2f (),
+.BR exp2l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR cbrt (3),
+.BR cexp2 (3),
+.BR exp (3),
+.BR exp10 (3),
+.BR sqrt (3)
diff --git a/man/man3/exp2f.3 b/man/man3/exp2f.3
new file mode 100644
index 000000000..b69beeace
--- /dev/null
+++ b/man/man3/exp2f.3
@@ -0,0 +1 @@
+.so man3/exp2.3
diff --git a/man/man3/exp2l.3 b/man/man3/exp2l.3
new file mode 100644
index 000000000..b69beeace
--- /dev/null
+++ b/man/man3/exp2l.3
@@ -0,0 +1 @@
+.so man3/exp2.3
diff --git a/man/man3/expf.3 b/man/man3/expf.3
new file mode 100644
index 000000000..4b1efda66
--- /dev/null
+++ b/man/man3/expf.3
@@ -0,0 +1 @@
+.so man3/exp.3
diff --git a/man/man3/expl.3 b/man/man3/expl.3
new file mode 100644
index 000000000..4b1efda66
--- /dev/null
+++ b/man/man3/expl.3
@@ -0,0 +1 @@
+.so man3/exp.3
diff --git a/man/man3/explicit_bzero.3 b/man/man3/explicit_bzero.3
new file mode 100644
index 000000000..8a43e76af
--- /dev/null
+++ b/man/man3/explicit_bzero.3
@@ -0,0 +1 @@
+.so man3/bzero.3
diff --git a/man/man3/expm1.3 b/man/man3/expm1.3
new file mode 100644
index 000000000..0e093a617
--- /dev/null
+++ b/man/man3/expm1.3
@@ -0,0 +1,165 @@
+'\" t
+.\" Copyright 1995 Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 2002-07-27 Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH expm1 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+expm1, expm1f, expm1l \- exponential minus 1
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double expm1(double " x );
+.BI "float expm1f(float " x );
+.BI "long double expm1l(long double " x );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR expm1 ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR expm1f (),
+.BR expm1l ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return a value equivalent to
+.P
+.nf
+    exp(x) \- 1
+.fi
+.P
+The result is computed in a way that is accurate even if the value of
+.I x
+is near
+zero\[em]a case where
+.I "exp(x) \- 1"
+would be inaccurate due to
+subtraction of two numbers that are nearly equal.
+.SH RETURN VALUE
+On success, these functions return
+.IR "exp(x)\ \-\ 1" .
+.P
+If
+.I x
+is a NaN,
+a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0),
++0 (\-0) is returned.
+.P
+If
+.I x
+is positive infinity, positive infinity is returned.
+.P
+If
+.I x
+is negative infinity, \-1 is returned.
+.P
+If the result overflows, a range error occurs,
+and the functions return
+.RB \- HUGE_VAL ,
+.RB \- HUGE_VALF ,
+or
+.RB \- HUGE_VALL ,
+respectively.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error, overflow
+.I errno
+is set to
+.B ERANGE
+(but see BUGS).
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.\"
+.\" POSIX.1 specifies an optional range error (underflow) if
+.\" x is subnormal.  glibc does not implement this.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR expm1 (),
+.BR expm1f (),
+.BR expm1l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+BSD.
+.SH BUGS
+Before glibc 2.17,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6778
+on certain architectures (e.g., x86, but not x86_64)
+.BR expm1 ()
+raised a bogus underflow floating-point exception
+for some large negative
+.I x
+values (where the function result approaches \-1).
+.P
+Before approximately glibc 2.11,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6814
+.\" e.g., expm1(1e5) through expm1(1.00199970127e5),
+.\" but not expm1(1.00199970128e5) and beyond.
+.BR expm1 ()
+raised a bogus invalid floating-point exception in addition to the expected
+overflow exception, and returned a NaN instead of positive infinity,
+for some large positive
+.I x
+values.
+.P
+Before glibc 2.11,
+.\" It looks like the fix was in glibc 2.11, or possibly glibc 2.12.
+.\" I have no test system for glibc 2.11, but glibc 2.12 passes.
+.\" From the source (sysdeps/i386/fpu/s_expm1.S) it looks
+.\" like the changes were in glibc 2.11.
+the glibc implementation did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6788
+.I errno
+to
+.B ERANGE
+when a range error occurred.
+.SH SEE ALSO
+.BR exp (3),
+.BR log (3),
+.BR log1p (3)
diff --git a/man/man3/expm1f.3 b/man/man3/expm1f.3
new file mode 100644
index 000000000..2c9e4eac1
--- /dev/null
+++ b/man/man3/expm1f.3
@@ -0,0 +1 @@
+.so man3/expm1.3
diff --git a/man/man3/expm1l.3 b/man/man3/expm1l.3
new file mode 100644
index 000000000..2c9e4eac1
--- /dev/null
+++ b/man/man3/expm1l.3
@@ -0,0 +1 @@
+.so man3/expm1.3
diff --git a/man/man3/fabs.3 b/man/man3/fabs.3
new file mode 100644
index 000000000..bfd04d76b
--- /dev/null
+++ b/man/man3/fabs.3
@@ -0,0 +1,92 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:42:04 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Added fabsl, fabsf, aeb, 2001-06-07
+.\"
+.TH fabs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fabs, fabsf, fabsl \- absolute value of floating-point number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double fabs(double " x );
+.BI "float fabsf(float " x );
+.BI "long double fabsl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fabsf (),
+.BR fabsl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the absolute value of the floating-point
+number
+.IR x .
+.SH RETURN VALUE
+These functions return the absolute value of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is \-0, +0 is returned.
+.P
+If
+.I x
+is negative infinity or positive infinity, positive infinity is returned.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fabs (),
+.BR fabsf (),
+.BR fabsl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR abs (3),
+.BR cabs (3),
+.BR ceil (3),
+.BR floor (3),
+.BR labs (3),
+.BR rint (3)
diff --git a/man/man3/fabsf.3 b/man/man3/fabsf.3
new file mode 100644
index 000000000..0426cf0f2
--- /dev/null
+++ b/man/man3/fabsf.3
@@ -0,0 +1 @@
+.so man3/fabs.3
diff --git a/man/man3/fabsl.3 b/man/man3/fabsl.3
new file mode 100644
index 000000000..0426cf0f2
--- /dev/null
+++ b/man/man3/fabsl.3
@@ -0,0 +1 @@
+.so man3/fabs.3
diff --git a/man/man3/fclose.3 b/man/man3/fclose.3
new file mode 100644
index 000000000..c8d044b9c
--- /dev/null
+++ b/man/man3/fclose.3
@@ -0,0 +1,102 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)fclose.3	6.7 (Berkeley) 6/29/91
+.\"
+.\" Converted for Linux, Mon Nov 29 15:19:14 1993, faith@cs.unc.edu
+.\"
+.\" Modified 2000-07-22 by Nicolás Lichtmaier <nick@debian.org>
+.\"
+.TH fclose 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fclose \- close a stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int fclose(FILE *" stream );
+.fi
+.SH DESCRIPTION
+The
+.BR fclose ()
+function flushes the stream pointed to by
+.I stream
+(writing any buffered output data using
+.BR fflush (3))
+and closes the underlying file descriptor.
+.SH RETURN VALUE
+Upon successful completion, 0 is returned.
+Otherwise,
+.B EOF
+is returned and
+.I errno
+is set to indicate the error.
+In either case, any further access
+(including another call to
+.BR fclose ())
+to the stream results in undefined behavior.
+.SH ERRORS
+.TP
+.B EBADF
+The file descriptor underlying
+.I stream
+is not valid.
+.\"  This error cannot occur unless you are mixing ANSI C stdio operations and
+.\"  low-level file operations on the same stream. If you do get this error,
+.\"  you must have closed the stream's low-level file descriptor using
+.\"  something like close(fileno(stream)).
+.P
+The
+.BR fclose ()
+function may also fail and set
+.I errno
+for any of the errors specified for the routines
+.BR close (2),
+.BR write (2),
+or
+.BR fflush (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fclose ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH NOTES
+Note that
+.BR fclose ()
+flushes only the user-space buffers provided by the
+C library.
+To ensure that the data is physically stored
+on disk the kernel buffers must be flushed too, for example, with
+.BR sync (2)
+or
+.BR fsync (2).
+.SH SEE ALSO
+.BR close (2),
+.BR fcloseall (3),
+.BR fflush (3),
+.BR fileno (3),
+.BR fopen (3),
+.BR setbuf (3)
diff --git a/man/man3/fcloseall.3 b/man/man3/fcloseall.3
new file mode 100644
index 000000000..0d9700268
--- /dev/null
+++ b/man/man3/fcloseall.3
@@ -0,0 +1,64 @@
+'\" t
+.\" Copyright (c) 2006 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH fcloseall 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fcloseall \- close all open streams
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <stdio.h>
+.P
+.B int fcloseall(void);
+.fi
+.SH DESCRIPTION
+The
+.BR fcloseall ()
+function closes all of the calling process's open streams.
+Buffered output for each stream is written before it is closed
+(as for
+.BR fflush (3));
+buffered input is discarded.
+.P
+The standard streams,
+.IR stdin ,
+.IR stdout ,
+and
+.I stderr
+are also closed.
+.SH RETURN VALUE
+This function returns 0 if all files were successfully closed;
+on error,
+.B EOF
+is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fcloseall ()
+T}	Thread safety	MT-Unsafe race:streams
+.TE
+.P
+The
+.BR fcloseall ()
+function does not lock the streams, so it is not thread-safe.
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR close (2),
+.BR fclose (3),
+.BR fflush (3),
+.BR fopen (3),
+.BR setbuf (3)
diff --git a/man/man3/fcvt.3 b/man/man3/fcvt.3
new file mode 100644
index 000000000..39d377098
--- /dev/null
+++ b/man/man3/fcvt.3
@@ -0,0 +1 @@
+.so man3/ecvt.3
diff --git a/man/man3/fcvt_r.3 b/man/man3/fcvt_r.3
new file mode 100644
index 000000000..41ce9ee8a
--- /dev/null
+++ b/man/man3/fcvt_r.3
@@ -0,0 +1 @@
+.so man3/ecvt_r.3
diff --git a/man/man3/fdim.3 b/man/man3/fdim.3
new file mode 100644
index 000000000..74f707402
--- /dev/null
+++ b/man/man3/fdim.3
@@ -0,0 +1,96 @@
+'\" t
+.\" Copyright 2003 Walter Harms, Andries Brouwer
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH fdim 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fdim, fdimf, fdiml \- positive difference
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double fdim(double " x ", double " y );
+.BI "float fdimf(float " x ", float " y );
+.BI "long double fdiml(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fdimf (),
+.BR fdiml ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions return the positive difference, max(\fIx\fP-\fIy\fP,0),
+between their arguments.
+.SH RETURN VALUE
+On success, these functions return the positive difference.
+.P
+If
+.I x
+or
+.I y
+is a NaN, a NaN is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fdim (),
+.BR fdimf (),
+.BR fdiml ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH BUGS
+Before glibc 2.24
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6796
+on certain architectures (e.g., x86, but not x86_64)
+these functions did not set
+.IR errno .
+.SH SEE ALSO
+.BR fmax (3)
diff --git a/man/man3/fdimf.3 b/man/man3/fdimf.3
new file mode 100644
index 000000000..a4058e45d
--- /dev/null
+++ b/man/man3/fdimf.3
@@ -0,0 +1 @@
+.so man3/fdim.3
diff --git a/man/man3/fdiml.3 b/man/man3/fdiml.3
new file mode 100644
index 000000000..a4058e45d
--- /dev/null
+++ b/man/man3/fdiml.3
@@ -0,0 +1 @@
+.so man3/fdim.3
diff --git a/man/man3/fdopen.3 b/man/man3/fdopen.3
new file mode 100644
index 000000000..9a4012491
--- /dev/null
+++ b/man/man3/fdopen.3
@@ -0,0 +1 @@
+.so man3/fopen.3
diff --git a/man/man3/fdopendir.3 b/man/man3/fdopendir.3
new file mode 100644
index 000000000..55b720e2a
--- /dev/null
+++ b/man/man3/fdopendir.3
@@ -0,0 +1 @@
+.so man3/opendir.3
diff --git a/man/man3/feclearexcept.3 b/man/man3/feclearexcept.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/feclearexcept.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fedisableexcept.3 b/man/man3/fedisableexcept.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fedisableexcept.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/feenableexcept.3 b/man/man3/feenableexcept.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/feenableexcept.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fegetenv.3 b/man/man3/fegetenv.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fegetenv.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fegetexcept.3 b/man/man3/fegetexcept.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fegetexcept.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fegetexceptflag.3 b/man/man3/fegetexceptflag.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fegetexceptflag.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fegetround.3 b/man/man3/fegetround.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fegetround.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/feholdexcept.3 b/man/man3/feholdexcept.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/feholdexcept.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fenv.3 b/man/man3/fenv.3
new file mode 100644
index 000000000..12e9f59f4
--- /dev/null
+++ b/man/man3/fenv.3
@@ -0,0 +1,334 @@
+'\" t
+.\" Copyright (c) 2000 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2000-08-14 added GNU additions from Andreas Jaeger
+.\" 2000-12-05 some changes inspired by acahalan's remarks
+.\"
+.TH fenv 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag,
+fetestexcept, fegetenv, fegetround, feholdexcept, fesetround,
+fesetenv, feupdateenv, feenableexcept, fedisableexcept,
+fegetexcept \- floating-point rounding and exception handling
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <fenv.h>
+.P
+.BI "int feclearexcept(int " excepts );
+.BI "int fegetexceptflag(fexcept_t *" flagp ", int " excepts );
+.BI "int feraiseexcept(int " excepts );
+.BI "int fesetexceptflag(const fexcept_t *" flagp ", int " excepts );
+.BI "int fetestexcept(int " excepts );
+.P
+.B "int fegetround(void);"
+.BI "int fesetround(int " rounding_mode );
+.P
+.BI "int fegetenv(fenv_t *" envp );
+.BI "int feholdexcept(fenv_t *" envp );
+.BI "int fesetenv(const fenv_t *" envp );
+.BI "int feupdateenv(const fenv_t *" envp );
+.fi
+.SH DESCRIPTION
+These eleven functions were defined in C99, and describe the handling
+of floating-point rounding and exceptions (overflow, zero-divide, etc.).
+.SS Exceptions
+The
+.I divide-by-zero
+exception occurs when an operation on finite numbers
+produces infinity as exact answer.
+.P
+The
+.I overflow
+exception occurs when a result has to be represented as a
+floating-point number, but has (much) larger absolute value than the
+largest (finite) floating-point number that is representable.
+.P
+The
+.I underflow
+exception occurs when a result has to be represented as a
+floating-point number, but has smaller absolute value than the smallest
+positive normalized floating-point number (and would lose much accuracy
+when represented as a denormalized number).
+.P
+The
+.I inexact
+exception occurs when the rounded result of an operation
+is not equal to the infinite precision result.
+It may occur whenever
+.I overflow
+or
+.I underflow
+occurs.
+.P
+The
+.I invalid
+exception occurs when there is no well-defined result
+for an operation, as for 0/0 or infinity \- infinity or sqrt(\-1).
+.SS Exception handling
+Exceptions are represented in two ways: as a single bit
+(exception present/absent), and these bits correspond in some
+implementation-defined way with bit positions in an integer,
+and also as an opaque structure that may contain more information
+about the exception (perhaps the code address where it occurred).
+.P
+Each of the macros
+.BR FE_DIVBYZERO ,
+.BR FE_INEXACT ,
+.BR FE_INVALID ,
+.BR FE_OVERFLOW ,
+.B FE_UNDERFLOW
+is defined when the implementation supports handling
+of the corresponding exception, and if so then
+defines the corresponding bit(s), so that one can call
+exception handling functions, for example, using the integer argument
+.BR FE_OVERFLOW | FE_UNDERFLOW .
+Other exceptions may be supported.
+The macro
+.B FE_ALL_EXCEPT
+is the bitwise OR of all bits corresponding to supported exceptions.
+.P
+The
+.BR feclearexcept ()
+function clears the supported exceptions represented by the bits
+in its argument.
+.P
+The
+.BR fegetexceptflag ()
+function stores a representation of the state of the exception flags
+represented by the argument
+.I excepts
+in the opaque object
+.IR *flagp .
+.P
+The
+.BR feraiseexcept ()
+function raises the supported exceptions represented by the bits in
+.IR excepts .
+.P
+The
+.BR fesetexceptflag ()
+function sets the complete status for the exceptions represented by
+.I excepts
+to the value
+.IR *flagp .
+This value must have been obtained by an earlier call of
+.BR fegetexceptflag ()
+with a last argument that contained all bits in
+.IR excepts .
+.P
+The
+.BR fetestexcept ()
+function returns a word in which the bits are set that were
+set in the argument
+.I excepts
+and for which the corresponding exception is currently set.
+.SS Rounding mode
+The rounding mode determines how the result of floating-point operations
+is treated when the result cannot be exactly represented in the significand.
+Various rounding modes may be provided:
+round to nearest (the default),
+round up (toward positive infinity),
+round down (toward negative infinity), and
+round toward zero.
+.P
+Each of the macros
+.BR FE_TONEAREST ,
+.BR FE_UPWARD ,
+.BR FE_DOWNWARD ,
+and
+.B FE_TOWARDZERO
+is defined when the implementation supports getting and setting
+the corresponding rounding direction.
+.P
+The
+.BR fegetround ()
+function returns the macro corresponding to the current
+rounding mode.
+.P
+The
+.BR fesetround ()
+function sets the rounding mode as specified by its argument
+and returns zero when it was successful.
+.P
+C99 and POSIX.1-2008 specify an identifier,
+.BR FLT_ROUNDS ,
+defined in
+.IR <float.h> ,
+which indicates the implementation-defined rounding
+behavior for floating-point addition.
+This identifier has one of the following values:
+.TP
+.B \-1
+The rounding mode is not determinable.
+.TP
+.B 0
+Rounding is toward 0.
+.TP
+.B 1
+Rounding is toward nearest number.
+.TP
+.B 2
+Rounding is toward positive infinity.
+.TP
+.B 3
+Rounding is toward negative infinity.
+.P
+Other values represent machine-dependent, nonstandard rounding modes.
+.P
+The value of
+.B FLT_ROUNDS
+should reflect the current rounding mode as set by
+.BR fesetround ()
+(but see BUGS).
+.SS Floating-point environment
+The entire floating-point environment, including
+control modes and status flags, can be handled
+as one opaque object, of type
+.IR fenv_t .
+The default environment is denoted by
+.B FE_DFL_ENV
+(of type
+.IR "const fenv_t\ *" ).
+This is the environment setup at program start and it is defined by
+ISO C to have round to nearest, all exceptions cleared and a nonstop
+(continue on exceptions) mode.
+.P
+The
+.BR fegetenv ()
+function saves the current floating-point environment in the object
+.IR *envp .
+.P
+The
+.BR feholdexcept ()
+function does the same, then clears all exception flags,
+and sets a nonstop (continue on exceptions) mode,
+if available.
+It returns zero when successful.
+.P
+The
+.BR fesetenv ()
+function restores the floating-point environment from
+the object
+.IR *envp .
+This object must be known to be valid, for example, the result of a call to
+.BR fegetenv ()
+or
+.BR feholdexcept ()
+or equal to
+.BR FE_DFL_ENV .
+This call does not raise exceptions.
+.P
+The
+.BR feupdateenv ()
+function installs the floating-point environment represented by
+the object
+.IR *envp ,
+except that currently raised exceptions are not cleared.
+After calling this function, the raised exceptions will be a bitwise OR
+of those previously set with those in
+.IR *envp .
+As before, the object
+.I *envp
+must be known to be valid.
+.SH RETURN VALUE
+These functions return zero on success and nonzero if an error occurred.
+.\" Earlier seven of these functions were listed as returning void.
+.\" This was corrected in Corrigendum 1 (ISO/IEC 9899:1999/Cor.1:2001(E))
+.\" of the C99 Standard.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.nh
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR feclearexcept (),
+.BR fegetexceptflag (),
+.BR feraiseexcept (),
+.BR fesetexceptflag (),
+.BR fetestexcept (),
+.BR fegetround (),
+.BR fesetround (),
+.BR fegetenv (),
+.BR feholdexcept (),
+.BR fesetenv (),
+.BR feupdateenv (),
+.BR feenableexcept (),
+.BR fedisableexcept (),
+.BR fegetexcept ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe
+T}
+.TE
+.hy
+.SH STANDARDS
+C11, POSIX.1-2008, IEC 60559 (IEC 559:1989), ANSI/IEEE 854.
+.SH HISTORY
+C99, POSIX.1-2001.
+glibc 2.1.
+.SH NOTES
+.SS glibc notes
+If possible, the GNU C Library defines a macro
+.B FE_NOMASK_ENV
+which represents an environment where every exception raised causes a
+trap to occur.
+You can test for this macro using
+.BR #ifdef .
+It is defined only if
+.B _GNU_SOURCE
+is defined.
+The C99 standard does not define a way to set individual bits in the
+floating-point mask, for example, to trap on specific flags.
+Since glibc 2.2, glibc supports the functions
+.BR feenableexcept ()
+and
+.BR fedisableexcept ()
+to set individual floating-point traps, and
+.BR fegetexcept ()
+to query the state.
+.P
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B "#include <fenv.h>"
+.P
+.BI "int feenableexcept(int " excepts );
+.BI "int fedisableexcept(int " excepts );
+.B "int fegetexcept(void);"
+.fi
+.P
+The
+.BR feenableexcept ()
+and
+.BR fedisableexcept ()
+functions enable (disable) traps for each of the exceptions represented by
+.I excepts
+and return the previous set of enabled exceptions when successful,
+and \-1 otherwise.
+The
+.BR fegetexcept ()
+function returns the set of all currently enabled exceptions.
+.SH BUGS
+C99 specifies that the value of
+.B FLT_ROUNDS
+should reflect changes to the current rounding mode, as set by
+.BR fesetround ().
+Currently,
+.\" Aug 08, glibc 2.8
+this does not occur:
+.B FLT_ROUNDS
+always has the value 1.
+.\" See http://gcc.gnu.org/ml/gcc/2002-02/msg01535.html
+.SH SEE ALSO
+.BR math_error (7)
diff --git a/man/man3/feof.3 b/man/man3/feof.3
new file mode 100644
index 000000000..3a95cca9f
--- /dev/null
+++ b/man/man3/feof.3
@@ -0,0 +1 @@
+.so man3/ferror.3
diff --git a/man/man3/feof_unlocked.3 b/man/man3/feof_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/feof_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/feraiseexcept.3 b/man/man3/feraiseexcept.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/feraiseexcept.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/ferror.3 b/man/man3/ferror.3
new file mode 100644
index 000000000..0baf2443a
--- /dev/null
+++ b/man/man3/ferror.3
@@ -0,0 +1,118 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" and Copyright (C) 2021 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)ferror.3	6.8 (Berkeley) 6/29/91
+.\"
+.\"
+.\" Converted for Linux, Mon Nov 29 14:24:40 1993, faith@cs.unc.edu
+.\"
+.TH ferror 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+clearerr, feof, ferror \- check and reset stream status
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "void clearerr(FILE *" stream );
+.BI "int feof(FILE *" stream );
+.BI "int ferror(FILE *" stream );
+.fi
+.SH DESCRIPTION
+The function
+.BR clearerr ()
+clears the end-of-file and error indicators for the stream pointed to by
+.IR stream .
+.P
+The function
+.BR feof ()
+tests the end-of-file indicator for the stream pointed to by
+.IR stream ,
+returning nonzero if it is set.
+The end-of-file indicator can be cleared only by the function
+.BR clearerr ().
+.P
+The function
+.BR ferror ()
+tests the error indicator for the stream pointed to by
+.IR stream ,
+returning nonzero if it is set.
+The error indicator can be reset only by the
+.BR clearerr ()
+function.
+.P
+For nonlocking counterparts, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+The
+.BR feof ()
+function returns nonzero if the end-of-file indicator is set for
+.IR stream ;
+otherwise, it returns zero.
+.P
+The
+.BR ferror ()
+function returns nonzero if the error indicator is set for
+.IR stream ;
+otherwise, it returns zero.
+.SH ERRORS
+These functions should not fail and do not set
+.IR errno .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR clearerr (),
+.BR feof (),
+.BR ferror ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH NOTES
+POSIX.1-2008 specifies
+.\"https://www.austingroupbugs.net/view.php?id=401
+that these functions shall not change the value of
+.I errno
+if
+.I stream
+is valid.
+.SH CAVEATS
+Normally,
+programs should read the return value of an input function,
+such as
+.BR fgetc (3),
+before using functions of the
+.BR feof (3)
+family.
+Only when the function returned the sentinel value
+.B EOF
+it makes sense to distinguish between the end of a file or an error with
+.BR feof (3)
+or
+.BR ferror (3).
+.SH SEE ALSO
+.BR open (2),
+.BR fdopen (3),
+.BR fileno (3),
+.BR stdio (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/ferror_unlocked.3 b/man/man3/ferror_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/ferror_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fesetenv.3 b/man/man3/fesetenv.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fesetenv.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fesetexceptflag.3 b/man/man3/fesetexceptflag.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fesetexceptflag.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fesetround.3 b/man/man3/fesetround.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fesetround.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fetestexcept.3 b/man/man3/fetestexcept.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/fetestexcept.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/feupdateenv.3 b/man/man3/feupdateenv.3
new file mode 100644
index 000000000..47668e719
--- /dev/null
+++ b/man/man3/feupdateenv.3
@@ -0,0 +1 @@
+.so man3/fenv.3
diff --git a/man/man3/fexecve.3 b/man/man3/fexecve.3
new file mode 100644
index 000000000..015d2e7fe
--- /dev/null
+++ b/man/man3/fexecve.3
@@ -0,0 +1,172 @@
+'\" t
+.\" Copyright (c) 2006, 2014, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH fexecve 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fexecve \- execute program specified via file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int fexecve(int " fd ", char *const " argv "[], char *const " envp []);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fexecve ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.BR fexecve ()
+performs the same task as
+.BR execve (2),
+with the difference that the file to be executed
+is specified via a file descriptor,
+.IR fd ,
+rather than via a pathname.
+The file descriptor
+.I fd
+must be opened read-only
+.RB ( O_RDONLY )
+or with the
+.B O_PATH
+flag
+and the caller must have permission to execute the file that it refers to.
+.SH RETURN VALUE
+A successful call to
+.BR fexecve ()
+never returns.
+On error, the function does return, with a result value of \-1, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Errors are as for
+.BR execve (2),
+with the following additions:
+.TP
+.B EINVAL
+.I fd
+is not a valid file descriptor, or
+.I argv
+is NULL, or
+.I envp
+is NULL.
+.TP
+.B ENOENT
+The close-on-exec flag is set on
+.IR fd ,
+and
+.I fd
+refers to a script.
+See BUGS.
+.TP
+.B ENOSYS
+The kernel does not provide the
+.BR execveat (2)
+system call, and the
+.I /proc
+filesystem could not be accessed.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fexecve ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.3.2.
+.P
+On Linux with glibc versions 2.26 and earlier,
+.BR fexecve ()
+is implemented using the
+.BR proc (5)
+filesystem, so
+.I /proc
+needs to be mounted and available at the time of the call.
+Since glibc 2.27,
+.\" glibc commit 43ffc53a352a67672210c9dd4959f6c6b7407e60
+if the underlying kernel supports the
+.BR execveat (2)
+system call, then
+.BR fexecve ()
+is implemented using that system call, with the benefit that
+.I /proc
+does not need to be mounted.
+.SH NOTES
+The idea behind
+.BR fexecve ()
+is to allow the caller to verify (checksum) the contents of
+an executable before executing it.
+Simply opening the file, checksumming the contents, and then doing an
+.BR execve (2)
+would not suffice, since, between the two steps, the filename,
+or a directory prefix of the pathname, could have been exchanged
+(by, for example, modifying the target of a symbolic link).
+.BR fexecve ()
+does not mitigate the problem that the
+.I contents
+of a file could be changed between the checksumming and the call to
+.BR fexecve ();
+for that, the solution is to ensure that the permissions on the file
+prevent it from being modified by malicious users.
+.P
+The natural idiom when using
+.BR fexecve ()
+is to set the close-on-exec flag on
+.IR fd ,
+so that the file descriptor does not leak through to the program
+that is executed.
+This approach is natural for two reasons.
+First, it prevents file descriptors being consumed unnecessarily.
+(The executed program normally has no need of a file descriptor
+that refers to the program itself.)
+Second, if
+.BR fexecve ()
+is used recursively,
+employing the close-on-exec flag prevents the file descriptor exhaustion
+that would result from the fact that each step in the recursion would
+cause one more file descriptor to be passed to the new program.
+(But see BUGS.)
+.SH BUGS
+If
+.I fd
+refers to a script (i.e., it is an executable text file that names
+a script interpreter with a first line that begins with the characters
+.IR #! )
+and the close-on-exec flag has been set for
+.IR fd ,
+then
+.BR fexecve ()
+fails with the error
+.BR ENOENT .
+This error occurs because,
+by the time the script interpreter is executed,
+.I fd
+has already been closed because of the close-on-exec flag.
+Thus, the close-on-exec flag can't be set on
+.I fd
+if it refers to a script, leading to the problems described in NOTES.
+.SH SEE ALSO
+.BR execve (2),
+.BR execveat (2)
diff --git a/man/man3/fflush.3 b/man/man3/fflush.3
new file mode 100644
index 000000000..6590af5e8
--- /dev/null
+++ b/man/man3/fflush.3
@@ -0,0 +1,115 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)fflush.3	5.4 (Berkeley) 6/29/91
+.\"
+.\" Converted for Linux, Mon Nov 29 15:22:01 1993, faith@cs.unc.edu
+.\"
+.\" Modified 2000-07-22 by Nicolás Lichtmaier <nick@debian.org>
+.\" Modified 2001-10-16 by John Levon <moz@compsoc.man.ac.uk>
+.\"
+.TH fflush 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fflush \- flush a stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int fflush(FILE *_Nullable " stream );
+.fi
+.SH DESCRIPTION
+For output streams,
+.BR fflush ()
+forces a write of all user-space buffered data for the given output or update
+.I stream
+via the stream's underlying write function.
+.P
+For input streams associated with seekable files
+(e.g., disk files, but not pipes or terminals),
+.BR fflush ()
+discards any buffered data that has been fetched from the underlying file,
+but has not been consumed by the application.
+.P
+The open status of the stream is unaffected.
+.P
+If the
+.I stream
+argument is NULL,
+.BR fflush ()
+flushes
+.I all
+open output streams.
+.\" mtk: POSIX specifies that only output streams are flushed for this case.
+.\" Also verified for glibc by experiment.
+.P
+For a nonlocking counterpart, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+Upon successful completion 0 is returned.
+Otherwise,
+.B EOF
+is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I stream
+is not an open stream, or is not open for writing.
+.P
+The function
+.BR fflush ()
+may also fail and set
+.I errno
+for any of the errors specified for
+.BR write (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fflush ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001, POSIX.1-2008.
+.P
+POSIX.1-2001 did not specify the behavior for flushing of input streams,
+but the behavior is specified in POSIX.1-2008.
+.SH NOTES
+Note that
+.BR fflush ()
+flushes only the user-space buffers provided by the C library.
+To ensure that the data is physically stored on disk
+the kernel buffers must be flushed too, for example, with
+.BR sync (2)
+or
+.BR fsync (2).
+.SH SEE ALSO
+.BR fsync (2),
+.BR sync (2),
+.BR write (2),
+.BR fclose (3),
+.BR fileno (3),
+.BR fopen (3),
+.BR fpurge (3),
+.BR setbuf (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/fflush_unlocked.3 b/man/man3/fflush_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fflush_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/ffs.3 b/man/man3/ffs.3
new file mode 100644
index 000000000..aab5f1099
--- /dev/null
+++ b/man/man3/ffs.3
@@ -0,0 +1,97 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:39:35 1993 by Rik Faith (faith@cs.unc.edu)
+.\"
+.\" Modified 2003 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH ffs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ffs, ffsl, ffsll \- find first bit set in a word
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <strings.h>
+.P
+.BI "int ffs(int " i );
+.BI "int ffsl(long " i );
+.BI "int ffsll(long long " i );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ffs ():
+.nf
+    Since glibc 2.12:
+        _XOPEN_SOURCE >= 700
+            || ! (_POSIX_C_SOURCE >= 200809L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+    Before glibc 2.12:
+        none
+.fi
+.P
+.BR ffsl (),
+.BR ffsll ():
+.nf
+    Since glibc 2.27:
+.\" glibc commit 68fe16dd327c895c08b9ee443b234c49c13b36e9
+        _DEFAULT_SOURCE
+    Before glibc 2.27:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR ffs ()
+function returns the position of the first
+(least significant) bit set in the word \fIi\fP.
+The least significant bit is position 1 and the
+most significant position is, for example, 32 or 64.
+The functions
+.BR ffsll ()
+and
+.BR ffsl ()
+do the same but take
+arguments of possibly different size.
+.SH RETURN VALUE
+These functions return the position of the first bit set,
+or 0 if no bits are set in
+.IR i .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ffs (),
+.BR ffsl (),
+.BR ffsll ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR ffs ()
+POSIX.1-2001, POSIX.1-2008, 4.3BSD.
+.TP
+.BR ffsl ()
+.TQ
+.BR ffsll ()
+GNU.
+.SH SEE ALSO
+.BR memchr (3)
diff --git a/man/man3/ffsl.3 b/man/man3/ffsl.3
new file mode 100644
index 000000000..23c4024a5
--- /dev/null
+++ b/man/man3/ffsl.3
@@ -0,0 +1 @@
+.so man3/ffs.3
diff --git a/man/man3/ffsll.3 b/man/man3/ffsll.3
new file mode 100644
index 000000000..23c4024a5
--- /dev/null
+++ b/man/man3/ffsll.3
@@ -0,0 +1 @@
+.so man3/ffs.3
diff --git a/man/man3/fgetc.3 b/man/man3/fgetc.3
new file mode 100644
index 000000000..d92fd8413
--- /dev/null
+++ b/man/man3/fgetc.3
@@ -0,0 +1,152 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 28 11:12:07 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Sep  8 15:48:13 1995 by Andries Brouwer (aeb@cwi.nl)
+.TH fgetc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fgetc, fgets, getc, getchar, ungetc \- input of characters and strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int fgetc(FILE *" stream );
+.BI "int getc(FILE *" stream );
+.B "int getchar(void);"
+.P
+.BI "char *fgets(char " s "[restrict ." size "], int " size ", \
+FILE *restrict " stream );
+.P
+.BI "int ungetc(int " c ", FILE *" stream );
+.fi
+.SH DESCRIPTION
+.BR fgetc ()
+reads the next character from
+.I stream
+and returns it as an
+.I unsigned char
+cast to an
+.IR int ,
+or
+.B EOF
+on end of file or error.
+.P
+.BR getc ()
+is equivalent to
+.BR fgetc ()
+except that it may be implemented as a macro which evaluates
+.I stream
+more than once.
+.P
+.BR getchar ()
+is equivalent to
+.BI "getc(" stdin ) \fR.
+.P
+.BR fgets ()
+reads in at most one less than
+.I size
+characters from
+.I stream
+and stores them into the buffer pointed to by
+.IR s .
+Reading stops after an
+.B EOF
+or a newline.
+If a newline is read, it is stored into the buffer.
+A terminating null byte (\[aq]\e0\[aq])
+is stored after the last character in the buffer.
+.P
+.BR ungetc ()
+pushes
+.I c
+back to
+.IR stream ,
+cast to
+.IR "unsigned char" ,
+where it is available for subsequent read operations.
+Pushed-back characters
+will be returned in reverse order; only one pushback is guaranteed.
+.P
+Calls to the functions described here can be mixed with each other and with
+calls to other input functions from the
+.I stdio
+library for the same input stream.
+.P
+For nonlocking counterparts, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+.BR fgetc (),
+.BR getc (),
+and
+.BR getchar ()
+return the character read as an
+.I unsigned char
+cast to an
+.I int
+or
+.B EOF
+on end of file or error.
+.P
+.BR fgets ()
+returns
+.I s
+on success, and NULL
+on error or when end of file occurs while no characters have been read.
+.P
+.BR ungetc ()
+returns
+.I c
+on success, or
+.B EOF
+on error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fgetc (),
+.BR fgets (),
+.BR getc (),
+.BR getchar (),
+.BR ungetc ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89.
+.SH NOTES
+It is not advisable to mix calls to input functions from the
+.I stdio
+library with low-level calls to
+.BR read (2)
+for the file descriptor associated with the input stream; the results
+will be undefined and very probably not what you want.
+.SH SEE ALSO
+.BR read (2),
+.BR write (2),
+.BR ferror (3),
+.BR fgetwc (3),
+.BR fgetws (3),
+.BR fopen (3),
+.BR fread (3),
+.BR fseek (3),
+.BR getline (3),
+.BR gets (3),
+.BR getwchar (3),
+.BR puts (3),
+.BR scanf (3),
+.BR ungetwc (3),
+.BR unlocked_stdio (3),
+.BR feature_test_macros (7)
diff --git a/man/man3/fgetc_unlocked.3 b/man/man3/fgetc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fgetc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fgetgrent.3 b/man/man3/fgetgrent.3
new file mode 100644
index 000000000..aea64ac21
--- /dev/null
+++ b/man/man3/fgetgrent.3
@@ -0,0 +1,118 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:38:44 1993 by Rik Faith (faith@cs.unc.edu)
+.TH fgetgrent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fgetgrent \- get group file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <sys/types.h>
+.B #include <grp.h>
+.P
+.BI "struct group *fgetgrent(FILE *" stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fgetgrent ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR fgetgrent ()
+function returns a pointer to a structure containing
+the group information from the file referred to by
+.IR stream .
+The first time it is called
+it returns the first entry; thereafter, it returns successive entries.
+The file referred to by
+.I stream
+must have the same format as
+.I /etc/group
+(see
+.BR group (5)).
+.P
+The \fIgroup\fP structure is defined in \fI<grp.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct group {
+    char   *gr_name;        /* group name */
+    char   *gr_passwd;      /* group password */
+    gid_t   gr_gid;         /* group ID */
+    char  **gr_mem;         /* NULL\-terminated array of pointers
+                               to names of group members */
+};
+.EE
+.in
+.SH RETURN VALUE
+The
+.BR fgetgrent ()
+function returns a pointer to a
+.I group
+structure,
+or NULL if there are no more entries or an error occurs.
+In the event of an error,
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient memory to allocate
+.I group
+structure.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fgetgrent ()
+T}	Thread safety	MT-Unsafe race:fgetgrent
+.TE
+.\" FIXME The marking is different from that in the glibc manual,
+.\" which has:
+.\"
+.\"    fgetgrent: MT-Unsafe race:fgrent
+.\"
+.\" We think race:fgrent in glibc may be hard for users to understand,
+.\" and have sent a patch to the GNU libc community for changing it to
+.\" race:fgetgrent, however, something about the copyright impeded the
+.\" progress.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4.
+.SH SEE ALSO
+.BR endgrent (3),
+.BR fgetgrent_r (3),
+.BR fopen (3),
+.BR getgrent (3),
+.BR getgrgid (3),
+.BR getgrnam (3),
+.BR putgrent (3),
+.BR setgrent (3),
+.BR group (5)
diff --git a/man/man3/fgetgrent_r.3 b/man/man3/fgetgrent_r.3
new file mode 100644
index 000000000..7c6dfe43a
--- /dev/null
+++ b/man/man3/fgetgrent_r.3
@@ -0,0 +1 @@
+.so man3/getgrent_r.3
diff --git a/man/man3/fgetpos.3 b/man/man3/fgetpos.3
new file mode 100644
index 000000000..a1487b5a8
--- /dev/null
+++ b/man/man3/fgetpos.3
@@ -0,0 +1 @@
+.so man3/fseek.3
diff --git a/man/man3/fgetpwent.3 b/man/man3/fgetpwent.3
new file mode 100644
index 000000000..038778033
--- /dev/null
+++ b/man/man3/fgetpwent.3
@@ -0,0 +1,127 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified Sat Jul 24 19:37:37 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon May 27 22:40:48 1996 by Martin Schulze (joey@linux.de)
+.\"
+.TH fgetpwent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fgetpwent \- get password file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <sys/types.h>
+.B #include <pwd.h>
+.P
+.BI "struct passwd *fgetpwent(FILE *" stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fgetpwent ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR fgetpwent ()
+function returns a pointer to a structure containing
+the broken out fields of a line in the file \fIstream\fP.
+The first time it is called it returns the first entry;
+thereafter, it returns successive entries.
+The file referred to by
+.I stream
+must have the same format as
+.I /etc/passwd
+(see
+.BR passwd (5)).
+.P
+The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct passwd {
+    char   *pw_name;       /* username */
+    char   *pw_passwd;     /* user password */
+    uid_t   pw_uid;        /* user ID */
+    gid_t   pw_gid;        /* group ID */
+    char   *pw_gecos;      /* real name */
+    char   *pw_dir;        /* home directory */
+    char   *pw_shell;      /* shell program */
+};
+.EE
+.in
+.SH RETURN VALUE
+The
+.BR fgetpwent ()
+function returns a pointer to a
+.I passwd
+structure, or NULL if
+there are no more entries or an error occurs.
+In the event of an error,
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient memory to allocate
+.I passwd
+structure.
+.SH FILES
+.TP
+.I /etc/passwd
+password database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fgetpwent ()
+T}	Thread safety	MT-Unsafe race:fgetpwent
+.TE
+.\" FIXME: The marking is different from that in the glibc manual,
+.\" which has:
+.\"
+.\"    fgetpwent: MT-Unsafe race:fpwent
+.\"
+.\" We think race:fpwent in glibc maybe hard for users to understand,
+.\" and have sent a patch to the GNU libc community for changing it to
+.\" race:fgetpwent, however, something about the copyright impeded the
+.\" progress.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4.
+.SH SEE ALSO
+.BR endpwent (3),
+.BR fgetpwent_r (3),
+.BR fopen (3),
+.BR getpw (3),
+.BR getpwent (3),
+.BR getpwnam (3),
+.BR getpwuid (3),
+.BR putpwent (3),
+.BR setpwent (3),
+.BR passwd (5)
diff --git a/man/man3/fgetpwent_r.3 b/man/man3/fgetpwent_r.3
new file mode 100644
index 000000000..b2393bb64
--- /dev/null
+++ b/man/man3/fgetpwent_r.3
@@ -0,0 +1 @@
+.so man3/getpwent_r.3
diff --git a/man/man3/fgets.3 b/man/man3/fgets.3
new file mode 100644
index 000000000..2f6585a10
--- /dev/null
+++ b/man/man3/fgets.3
@@ -0,0 +1 @@
+.so man3/fgetc.3
diff --git a/man/man3/fgets_unlocked.3 b/man/man3/fgets_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fgets_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fgetspent.3 b/man/man3/fgetspent.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/fgetspent.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/fgetspent_r.3 b/man/man3/fgetspent_r.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/fgetspent_r.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/fgetwc.3 b/man/man3/fgetwc.3
new file mode 100644
index 000000000..e3d17bfd2
--- /dev/null
+++ b/man/man3/fgetwc.3
@@ -0,0 +1,106 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification
+.\"      http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.\" Modified Tue Oct 16 23:18:40 BST 2001 by John Levon <moz@compsoc.man.ac.uk>
+.TH fgetwc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fgetwc, getwc \- read a wide character from a FILE stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <wchar.h>
+.P
+.BI "wint_t fgetwc(FILE *" stream );
+.BI "wint_t getwc(FILE *" stream );
+.fi
+.SH DESCRIPTION
+The
+.BR fgetwc ()
+function is the wide-character equivalent
+of the
+.BR fgetc (3)
+function.
+It reads a wide character from \fIstream\fP and returns it.
+If the end of stream is reached, or if \fIferror(stream)\fP becomes true,
+it returns
+.BR WEOF .
+If a wide-character conversion error occurs, it sets
+\fIerrno\fP to \fBEILSEQ\fP and returns
+.BR WEOF .
+.P
+The
+.BR getwc ()
+function or macro functions identically to
+.BR fgetwc ().
+It may be implemented as a macro, and may evaluate its argument
+more than once.
+There is no reason ever to use it.
+.P
+For nonlocking counterparts, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+On success,
+.BR fgetwc ()
+returns the next wide-character from the stream.
+Otherwise,
+.B WEOF
+is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Apart from the usual ones, there is
+.TP
+.B EILSEQ
+The data obtained from the input stream does not
+form a valid character.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fgetwc (),
+.BR getwc ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR fgetwc ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+In the absence of additional information passed to the
+.BR fopen (3)
+call, it is
+reasonable to expect that
+.BR fgetwc ()
+will actually read a multibyte sequence
+from the stream and then convert it to a wide character.
+.SH SEE ALSO
+.BR fgetws (3),
+.BR fputwc (3),
+.BR ungetwc (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/fgetwc_unlocked.3 b/man/man3/fgetwc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fgetwc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fgetws.3 b/man/man3/fgetws.3
new file mode 100644
index 000000000..a41573b6f
--- /dev/null
+++ b/man/man3/fgetws.3
@@ -0,0 +1,91 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification
+.\"     http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.\" Modified Tue Oct 16 23:18:40 BST 2001 by John Levon <moz@compsoc.man.ac.uk>
+.TH fgetws 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fgetws \- read a wide-character string from a FILE stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *fgetws(wchar_t " ws "[restrict ." n "], int " n \
+", FILE *restrict " stream );
+.fi
+.SH DESCRIPTION
+The
+.BR fgetws ()
+function is the wide-character equivalent
+of the
+.BR fgets (3)
+function.
+It reads a string of at most \fIn\-1\fP wide characters into the
+wide-character array pointed to by \fIws\fP,
+and adds a terminating null wide character (L\[aq]\e0\[aq]).
+It stops reading wide characters after it has encountered and
+stored a newline wide character.
+It also stops when end of stream is reached.
+.P
+The programmer must ensure that there is room for at least \fIn\fP wide
+characters at \fIws\fP.
+.P
+For a nonlocking counterpart, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+The
+.BR fgetws ()
+function, if successful, returns \fIws\fP.
+If end of stream
+was already reached or if an error occurred, it returns NULL.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fgetws ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR fgetws ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+In the absence of additional information passed to the
+.BR fopen (3)
+call, it is
+reasonable to expect that
+.BR fgetws ()
+will actually read a multibyte string
+from the stream and then convert it to a wide-character string.
+.P
+This function is unreliable,
+because it does not permit to deal properly with
+null wide characters that may be present in the input.
+.SH SEE ALSO
+.BR fgetwc (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/fgetws_unlocked.3 b/man/man3/fgetws_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fgetws_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fileno.3 b/man/man3/fileno.3
new file mode 100644
index 000000000..1e9954626
--- /dev/null
+++ b/man/man3/fileno.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" and Copyright (C) 2021 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" Converted for Linux, Mon Nov 29 14:24:40 1993, faith@cs.unc.edu
+.\" Added remark on EBADF for fileno, aeb, 2001-03-22
+.\"
+.TH fileno 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fileno \- obtain file descriptor of a stdio stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int fileno(FILE *" stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fileno ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+The function
+.BR fileno ()
+examines the argument
+.I stream
+and returns the integer file descriptor used to implement this stream.
+The file descriptor is still owned by
+.I stream
+and will be closed when
+.BR fclose (3)
+is called.
+Duplicate the file descriptor with
+.BR dup (2)
+before passing it to code that might close it.
+.P
+For the nonlocking counterpart, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+On success,
+.BR fileno ()
+returns the file descriptor associated with
+.IR stream .
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I stream
+is not associated with a file.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fileno ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR open (2),
+.BR fdopen (3),
+.BR stdio (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/fileno_unlocked.3 b/man/man3/fileno_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fileno_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/finite.3 b/man/man3/finite.3
new file mode 100644
index 000000000..246a82a1f
--- /dev/null
+++ b/man/man3/finite.3
@@ -0,0 +1,143 @@
+'\" t
+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH finite 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+finite, finitef, finitel, isinf, isinff, isinfl, isnan, isnanf, isnanl \-
+BSD floating-point classification functions
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "int finite(double " x );
+.BI "int finitef(float " x );
+.BI "int finitel(long double " x );
+.P
+.BI "int isinf(double " x );
+.BI "int isinff(float " x );
+.BI "int isinfl(long double " x );
+.P
+.BI "int isnan(double " x );
+.BI "int isnanf(float " x );
+.BI "int isnanl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR finite (),
+.BR finitef (),
+.BR finitel ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.P
+.BR isinf ():
+    _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR isinff (),
+.BR isinfl ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR isnan ():
+.nf
+    _XOPEN_SOURCE || _ISOC99_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR isnanf (),
+.BR isnanl ():
+.nf
+    _XOPEN_SOURCE >= 600
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR finite (),
+.BR finitef (),
+and
+.BR finitel ()
+functions return a nonzero value if
+.I x
+is neither infinite
+nor a "not-a-number" (NaN) value, and 0 otherwise.
+.P
+The
+.BR isnan (),
+.BR isnanf (),
+and
+.BR isnanl ()
+functions return a nonzero value if
+.I x
+is a NaN value,
+and 0 otherwise.
+.P
+The
+.BR isinf (),
+.BR isinff (),
+and
+.BR isinfl ()
+functions return 1 if
+.I x
+is positive infinity, \-1 if
+.I x
+is negative infinity, and 0 otherwise.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR finite (),
+.BR finitef (),
+.BR finitel (),
+.BR isinf (),
+.BR isinff (),
+.BR isinfl (),
+.BR isnan (),
+.BR isnanf (),
+.BR isnanl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH NOTES
+Note that these functions are obsolete.
+C99 defines macros
+.BR isfinite (),
+.BR isinf (),
+and
+.BR isnan ()
+(for all types) replacing them.
+Further note that the C99
+.BR isinf ()
+has weaker guarantees on the return value.
+See
+.BR fpclassify (3).
+.\"
+.\" finite* not on HP-UX; they exist on Tru64.
+.\" .SH HISTORY
+.\" The
+.\" .BR finite ()
+.\" function occurs in 4.3BSD.
+.\" see IEEE.3 in the 4.3BSD manual
+.SH SEE ALSO
+.BR fpclassify (3)
diff --git a/man/man3/finitef.3 b/man/man3/finitef.3
new file mode 100644
index 000000000..19f709b1c
--- /dev/null
+++ b/man/man3/finitef.3
@@ -0,0 +1 @@
+.so man3/finite.3
diff --git a/man/man3/finitel.3 b/man/man3/finitel.3
new file mode 100644
index 000000000..19f709b1c
--- /dev/null
+++ b/man/man3/finitel.3
@@ -0,0 +1 @@
+.so man3/finite.3
diff --git a/man/man3/flockfile.3 b/man/man3/flockfile.3
new file mode 100644
index 000000000..86b0f7ac5
--- /dev/null
+++ b/man/man3/flockfile.3
@@ -0,0 +1,133 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH flockfile 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+flockfile, ftrylockfile, funlockfile \- lock FILE for stdio
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "void flockfile(FILE *" filehandle );
+.BI "int ftrylockfile(FILE *" filehandle );
+.BI "void funlockfile(FILE *" filehandle );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.nf
+    /* Since glibc 2.24: */ _POSIX_C_SOURCE >= 199309L
+        || /* glibc <= 2.23: */ _POSIX_C_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The stdio functions are thread-safe.
+This is achieved by assigning
+to each
+.I FILE
+object a lockcount and (if the lockcount is nonzero)
+an owning thread.
+For each library call, these functions wait until the
+.I FILE
+object
+is no longer locked by a different thread, then lock it, do the
+requested I/O, and unlock the object again.
+.P
+(Note: this locking has nothing to do with the file locking done
+by functions like
+.BR flock (2)
+and
+.BR lockf (3).)
+.P
+All this is invisible to the C-programmer, but there may be two
+reasons to wish for more detailed control.
+On the one hand, maybe
+a series of I/O actions by one thread belongs together, and should
+not be interrupted by the I/O of some other thread.
+On the other hand, maybe the locking overhead should be avoided
+for greater efficiency.
+.P
+To this end, a thread can explicitly lock the
+.I FILE
+object,
+then do its series of I/O actions, then unlock.
+This prevents
+other threads from coming in between.
+If the reason for doing
+this was to achieve greater efficiency, one does the I/O with
+the nonlocking versions of the stdio functions: with
+.BR getc_unlocked (3)
+and
+.BR putc_unlocked (3)
+instead of
+.BR getc (3)
+and
+.BR putc (3).
+.P
+The
+.BR flockfile ()
+function waits for
+.I *filehandle
+to be
+no longer locked by a different thread, then makes the
+current thread owner of
+.IR *filehandle ,
+and increments
+the lockcount.
+.P
+The
+.BR funlockfile ()
+function decrements the lock count.
+.P
+The
+.BR ftrylockfile ()
+function is a nonblocking version
+of
+.BR flockfile ().
+It does nothing in case some other thread
+owns
+.IR *filehandle ,
+and it obtains ownership and increments
+the lockcount otherwise.
+.SH RETURN VALUE
+The
+.BR ftrylockfile ()
+function returns zero for success
+(the lock was obtained), and nonzero for failure.
+.SH ERRORS
+None.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR flockfile (),
+.BR ftrylockfile (),
+.BR funlockfile ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+These functions are available when
+.B _POSIX_THREAD_SAFE_FUNCTIONS
+is defined.
+.SH SEE ALSO
+.BR unlocked_stdio (3)
diff --git a/man/man3/floor.3 b/man/man3/floor.3
new file mode 100644
index 000000000..2df4489ba
--- /dev/null
+++ b/man/man3/floor.3
@@ -0,0 +1,105 @@
+'\" t
+.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH floor 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+floor, floorf, floorl \- largest integral value not greater than argument
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double floor(double " x );
+.BI "float floorf(float " x );
+.BI "long double floorl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR floorf (),
+.BR floorl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the largest integral value that is not greater than
+.IR x .
+.P
+For example,
+.I floor(0.5)
+is 0.0, and
+.I floor(\-0.5)
+is \-1.0.
+.SH RETURN VALUE
+These functions return the floor of
+.IR x .
+.P
+If
+.I x
+is integral, +0, \-0, NaN, or an infinity,
+.I x
+itself is returned.
+.SH ERRORS
+No errors occur.
+POSIX.1-2001 documents a range error for overflows, but see NOTES.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR floor (),
+.BR floorf (),
+.BR floorl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.P
+SUSv2 and POSIX.1-2001 contain text about overflow (which might set
+.I errno
+to
+.BR ERANGE ,
+or raise an
+.B FE_OVERFLOW
+exception).
+In practice, the result cannot overflow on any current machine,
+so this error-handling stuff is just nonsense.
+.\" The POSIX.1-2001 APPLICATION USAGE SECTION discusses this point.
+(More precisely, overflow can happen only when the maximum value
+of the exponent is smaller than the number of mantissa bits.
+For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
+the maximum value of the exponent is 127 (respectively, 1023),
+and the number of mantissa bits
+including the implicit bit
+is 24 (respectively, 53).)
+.SH SEE ALSO
+.BR ceil (3),
+.BR lrint (3),
+.BR nearbyint (3),
+.BR rint (3),
+.BR round (3),
+.BR trunc (3)
diff --git a/man/man3/floorf.3 b/man/man3/floorf.3
new file mode 100644
index 000000000..1d8e79b22
--- /dev/null
+++ b/man/man3/floorf.3
@@ -0,0 +1 @@
+.so man3/floor.3
diff --git a/man/man3/floorl.3 b/man/man3/floorl.3
new file mode 100644
index 000000000..1d8e79b22
--- /dev/null
+++ b/man/man3/floorl.3
@@ -0,0 +1 @@
+.so man3/floor.3
diff --git a/man/man3/fma.3 b/man/man3/fma.3
new file mode 100644
index 000000000..a4d2330a6
--- /dev/null
+++ b/man/man3/fma.3
@@ -0,0 +1,167 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Modified 2004-11-15, Added further text on FLT_ROUNDS
+.\" 	as suggested by AEB and Fabian Kreutz
+.\"
+.TH fma 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fma, fmaf, fmal \- floating-point multiply and add
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double fma(double " x ", double " y ", double " z );
+.BI "float fmaf(float " x ", float " y ", float " z );
+.BI "long double fmal(long double " x ", long double " y ", long double " z );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fma (),
+.BR fmaf (),
+.BR fmal ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions compute
+.IR x " * " y " + " z .
+The result is rounded as one ternary operation according to the
+current rounding mode (see
+.BR fenv (3)).
+.SH RETURN VALUE
+These functions return the value of
+.IR x " * " y " + " z ,
+rounded as one ternary operation.
+.P
+If
+.I x
+or
+.I y
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+times
+.I y
+is an exact infinity, and
+.I z
+is an infinity with the opposite sign,
+a domain error occurs,
+and a NaN is returned.
+.P
+.\" POSIX.1-2008 allows some possible differences for the following two
+.\" domain error cases, but on Linux they are treated the same (AFAICS).
+.\" Nevertheless, we'll mirror POSIX.1 and describe the two cases
+.\" separately.
+If one of
+.I x
+or
+.I y
+is an infinity, the other is 0, and
+.I z
+is not a NaN,
+a domain error occurs, and
+a NaN is returned.
+.\" POSIX.1 says that a NaN or an implementation-defined value shall
+.\" be returned for this case.
+.P
+If one of
+.I x
+or
+.I y
+is an infinity, and the other is 0, and
+.I z
+is a NaN,
+.\" POSIX.1 makes the domain error optional for this case.
+a domain error occurs, and
+a NaN is returned.
+.P
+If
+.I x
+times
+.I y
+is not an infinity times zero (or vice versa), and
+.I z
+is a NaN,
+a NaN is returned.
+.P
+If the result overflows,
+a range error occurs, and
+an infinity with the correct sign is returned.
+.P
+If the result underflows,
+a range error occurs, and
+a signed 0 is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP * \fIy\fP + \fIz\fP, \
+or \fIx\fP * \fIy\fP is invalid and \fIz\fP is not a NaN
+.\" .I errno
+.\" is set to
+.\" .BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Range error: result overflow
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error: result underflow
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.P
+These functions do not set
+.IR errno .
+.\" FIXME . Is it intentional that these functions do not set errno?
+.\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6801
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fma (),
+.BR fmaf (),
+.BR fmal ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR remainder (3),
+.BR remquo (3)
diff --git a/man/man3/fmaf.3 b/man/man3/fmaf.3
new file mode 100644
index 000000000..e050da05f
--- /dev/null
+++ b/man/man3/fmaf.3
@@ -0,0 +1 @@
+.so man3/fma.3
diff --git a/man/man3/fmal.3 b/man/man3/fmal.3
new file mode 100644
index 000000000..e050da05f
--- /dev/null
+++ b/man/man3/fmal.3
@@ -0,0 +1 @@
+.so man3/fma.3
diff --git a/man/man3/fmax.3 b/man/man3/fmax.3
new file mode 100644
index 000000000..ea16797a7
--- /dev/null
+++ b/man/man3/fmax.3
@@ -0,0 +1,73 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH fmax 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fmax, fmaxf, fmaxl \- determine maximum of two floating-point numbers
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double fmax(double " x ", double " y );
+.BI "float fmaxf(float " x ", float " y );
+.BI "long double fmaxl(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fmax (),
+.BR fmaxf (),
+.BR fmaxl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions return the larger value of
+.I x
+and
+.IR y .
+.SH RETURN VALUE
+These functions return the maximum of
+.I x
+and
+.IR y .
+.P
+If one argument is a NaN, the other argument is returned.
+.P
+If both arguments are NaN, a NaN is returned.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fmax (),
+.BR fmaxf (),
+.BR fmaxl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR fdim (3),
+.BR fmin (3)
diff --git a/man/man3/fmaxf.3 b/man/man3/fmaxf.3
new file mode 100644
index 000000000..5f68a861e
--- /dev/null
+++ b/man/man3/fmaxf.3
@@ -0,0 +1 @@
+.so man3/fmax.3
diff --git a/man/man3/fmaxl.3 b/man/man3/fmaxl.3
new file mode 100644
index 000000000..5f68a861e
--- /dev/null
+++ b/man/man3/fmaxl.3
@@ -0,0 +1 @@
+.so man3/fmax.3
diff --git a/man/man3/fmemopen.3 b/man/man3/fmemopen.3
new file mode 100644
index 000000000..385fcdcc9
--- /dev/null
+++ b/man/man3/fmemopen.3
@@ -0,0 +1,352 @@
+'\" t
+.\" Copyright 2005, 2012, 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH fmemopen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fmemopen \-  open memory as stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "FILE *fmemopen(void " buf [. size "], size_t " size ", \
+const char *" mode );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fmemopen ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR fmemopen ()
+function opens a stream that permits the access specified by
+.IR mode .
+The stream allows I/O to be performed on the string or memory buffer
+pointed to by
+.IR buf .
+.P
+The
+.I mode
+argument specifies the semantics of I/O on the stream,
+and is one of the following:
+.TP
+.I r
+The stream is opened for reading.
+.TP
+.I w
+The stream is opened for writing.
+.TP
+.I a
+Append; open the stream for writing,
+with the initial buffer position set to the first null byte.
+.TP
+.I r+
+Open the stream for reading and writing.
+.TP
+.I w+
+Open the stream for reading and writing.
+The buffer contents are truncated
+(i.e., \[aq]\e0\[aq] is placed in the first byte of the buffer).
+.TP
+.I a+
+Append; open the stream for reading and writing,
+with the initial buffer position set to the first null byte.
+.P
+The stream maintains the notion of a current position,
+the location where the next I/O operation will be performed.
+The current position is implicitly updated by I/O operations.
+It can be explicitly updated using
+.BR fseek (3),
+and determined using
+.BR ftell (3).
+In all modes other than append,
+the initial position is set to the start of the buffer.
+In append mode, if no null byte is found within the buffer,
+then the initial position is
+.IR size+1 .
+.P
+If
+.I buf
+is specified as NULL, then
+.BR fmemopen ()
+allocates a buffer of
+.I size
+bytes.
+This is useful for an application that wants to write data to
+a temporary buffer and then read it back again.
+The initial position is set to the start of the buffer.
+The buffer is automatically freed when the stream is closed.
+Note that the caller has no way to obtain a pointer to the
+temporary buffer allocated by this call (but see
+.BR open_memstream (3)).
+.P
+If
+.I buf
+is not NULL, then it should point to a buffer of at least
+.I size
+bytes allocated by the caller.
+.P
+When a stream that has been opened for writing is flushed
+.RB ( fflush (3))
+or closed
+.RB ( fclose (3)),
+a null byte is written at the end of the buffer if there is space.
+The caller should ensure that an extra byte is available in the
+buffer
+(and that
+.I size
+counts that byte)
+to allow for this.
+.P
+In a stream opened for reading,
+null bytes (\[aq]\e0\[aq]) in the buffer do not cause read
+operations to return an end-of-file indication.
+A read from the buffer will indicate end-of-file
+only when the current buffer position advances
+.I size
+bytes past the start of the buffer.
+.P
+Write operations take place either at the current position
+(for modes other than append), or at the current size of the stream
+(for append modes).
+.P
+Attempts to write more than
+.I size
+bytes to the buffer result in an error.
+By default, such errors will be visible
+(by the absence of data) only when the
+.I stdio
+buffer is flushed.
+Disabling buffering with the following call
+may be useful to detect errors at the time of an output operation:
+.P
+.in +4n
+.EX
+setbuf(stream, NULL);
+.EE
+.in
+.SH RETURN VALUE
+Upon successful completion,
+.BR fmemopen ()
+returns a
+.I FILE
+pointer.
+Otherwise, NULL is returned and
+.I errno
+is set to indicate the error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fmemopen (),
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 1.0.x.
+POSIX.1-2008.
+.P
+POSIX.1-2008 specifies that \[aq]b\[aq] in
+.I mode
+shall be ignored.
+However, Technical Corrigendum 1
+.\" http://austingroupbugs.net/view.php?id=396
+adjusts the standard to allow implementation-specific treatment for this case,
+thus permitting the glibc treatment of \[aq]b\[aq].
+.P
+With glibc 2.22, binary mode (see below) was removed,
+many longstanding bugs in the implementation of
+.BR fmemopen ()
+were fixed, and a new versioned symbol was created for this interface.
+.\"
+.SS Binary mode
+From glibc 2.9 to glibc 2.21, the glibc implementation of
+.BR fmemopen ()
+supported a "binary" mode,
+enabled by specifying the letter \[aq]b\[aq] as the second character in
+.IR mode .
+In this mode,
+writes don't implicitly add a terminating null byte, and
+.BR fseek (3)
+.B SEEK_END
+is relative to the end of the buffer (i.e., the value specified by the
+.I size
+argument), rather than the current string length.
+.P
+An API bug afflicted the implementation of binary mode:
+to specify binary mode, the \[aq]b\[aq] must be the
+.I second
+character in
+.IR mode .
+Thus, for example, "wb+" has the desired effect, but "w+b" does not.
+This is inconsistent with the treatment of
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=12836
+.I mode
+by
+.BR fopen (3).
+.P
+Binary mode was removed in glibc 2.22; a \[aq]b\[aq] specified in
+.I mode
+has no effect.
+.SH NOTES
+There is no file descriptor associated with the file stream
+returned by this function
+(i.e.,
+.BR fileno (3)
+will return an error if called on the returned stream).
+.SH BUGS
+Before glibc 2.22, if
+.I size
+is specified as zero,
+.BR fmemopen ()
+fails with the error
+.BR EINVAL .
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=11216
+It would be more consistent if this case successfully created
+a stream that then returned end-of-file on the first attempt at reading;
+since glibc 2.22, the glibc implementation provides that behavior.
+.P
+Before glibc 2.22,
+specifying append mode ("a" or "a+") for
+.BR fmemopen ()
+sets the initial buffer position to the first null byte, but
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=13152
+(if the current position is reset to a location other than
+the end of the stream)
+does not force subsequent writes to append at the end of the stream.
+This bug is fixed in glibc 2.22.
+.P
+Before glibc 2.22, if the
+.I mode
+argument to
+.BR fmemopen ()
+specifies append ("a" or "a+"), and the
+.I size
+argument does not cover a null byte in
+.IR buf ,
+then, according to POSIX.1-2008,
+the initial buffer position should be set to
+the next byte after the end of the buffer.
+However, in this case the glibc
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=13151
+.BR fmemopen ()
+sets the buffer position to \-1.
+This bug is fixed in glibc 2.22.
+.P
+Before glibc 2.22,
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=14292
+when a call to
+.BR fseek (3)
+with a
+.I whence
+value of
+.B SEEK_END
+was performed on a stream created by
+.BR fmemopen (),
+the
+.I offset
+was
+.I subtracted
+from the end-of-stream position, instead of being added.
+This bug is fixed in glibc 2.22.
+.P
+The glibc 2.9 addition of "binary" mode for
+.BR fmemopen ()
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=6544
+silently changed the ABI: previously,
+.BR fmemopen ()
+ignored \[aq]b\[aq] in
+.IR mode .
+.SH EXAMPLES
+The program below uses
+.BR fmemopen ()
+to open an input buffer, and
+.BR open_memstream (3)
+to open a dynamically sized output buffer.
+The program scans its input string (taken from the program's
+first command-line argument) reading integers,
+and writes the squares of these integers to the output buffer.
+An example of the output produced by this program is the following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \[aq]1 23 43\[aq]"
+size=11; ptr=1 529 1849
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (fmemopen.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    FILE *out, *in;
+    int v, s;
+    size_t size;
+    char *ptr;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s \[aq]<num>...\[aq]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    in = fmemopen(argv[1], strlen(argv[1]), "r");
+    if (in == NULL)
+        err(EXIT_FAILURE, "fmemopen");
+\&
+    out = open_memstream(&ptr, &size);
+    if (out == NULL)
+        err(EXIT_FAILURE, "open_memstream");
+\&
+    for (;;) {
+        s = fscanf(in, "%d", &v);
+        if (s <= 0)
+            break;
+\&
+        s = fprintf(out, "%d ", v * v);
+        if (s == \-1)
+            err(EXIT_FAILURE, "fprintf");
+    }
+\&
+    fclose(in);
+    fclose(out);
+\&
+    printf("size=%zu; ptr=%s\en", size, ptr);
+\&
+    free(ptr);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fopen (3),
+.BR fopencookie (3),
+.BR open_memstream (3)
diff --git a/man/man3/fmin.3 b/man/man3/fmin.3
new file mode 100644
index 000000000..23aa01cc3
--- /dev/null
+++ b/man/man3/fmin.3
@@ -0,0 +1,73 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH fmin 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fmin, fminf, fminl \- determine minimum of two floating-point numbers
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double fmin(double " x ", double " y );
+.BI "float fminf(float " x ", float " y );
+.BI "long double fminl(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fmin (),
+.BR fminf (),
+.BR fminl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions return the lesser value of
+.I x
+and
+.IR y .
+.SH RETURN VALUE
+These functions return the minimum of
+.I x
+and
+.IR y .
+.P
+If one argument is a NaN, the other argument is returned.
+.P
+If both arguments are NaN, a NaN is returned.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fmin (),
+.BR fminf (),
+.BR fminl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR fdim (3),
+.BR fmax (3)
diff --git a/man/man3/fminf.3 b/man/man3/fminf.3
new file mode 100644
index 000000000..a86d77d74
--- /dev/null
+++ b/man/man3/fminf.3
@@ -0,0 +1 @@
+.so man3/fmin.3
diff --git a/man/man3/fminl.3 b/man/man3/fminl.3
new file mode 100644
index 000000000..a86d77d74
--- /dev/null
+++ b/man/man3/fminl.3
@@ -0,0 +1 @@
+.so man3/fmin.3
diff --git a/man/man3/fmod.3 b/man/man3/fmod.3
new file mode 100644
index 000000000..d6c76c7a3
--- /dev/null
+++ b/man/man3/fmod.3
@@ -0,0 +1,183 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH fmod 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fmod, fmodf, fmodl \- floating-point remainder function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double fmod(double " x ", double " y );
+.BI "float fmodf(float " x ", float " y );
+.BI "long double fmodl(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fmodf (),
+.BR fmodl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions compute the floating-point remainder of dividing
+.I x
+by
+.IR y .
+The return value is
+.I x
+\-
+.I n
+*
+.IR y ,
+where
+.I n
+is the quotient of
+.I x
+/
+.IR y ,
+rounded toward zero to an integer.
+.P
+To obtain the modulus, more specifically, the Least Positive Residue,
+you will need to adjust the result from fmod like so:
+.P
+.in +4n
+.nf
+z = fmod(x, y);
+if (z < 0)
+	z += y;
+.fi
+.in
+.P
+An alternate way to express this is with
+.IR "fmod(fmod(x, y) + y, y)" ,
+but the second
+.BR fmod ()
+usually costs way more than the one branch.
+.SH RETURN VALUE
+On success, these
+functions return the value \fIx\fP\ \-\ \fIn\fP*\fIy\fP,
+for some integer
+.IR n ,
+such that the returned value has the same sign as
+.I x
+and a magnitude less than the magnitude of
+.IR y .
+.P
+If
+.I x
+or
+.I y
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is an infinity,
+a domain error occurs, and
+a NaN is returned.
+.P
+If
+.I y
+is zero,
+a domain error occurs, and
+a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0), and
+.I y
+is not zero, +0 (\-0) is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is an infinity
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Domain error: \fIy\fP is zero
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.\" POSIX.1 documents an optional underflow error, but AFAICT it doesn't
+.\" (can't?) occur -- mtk, Jul 2008
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fmod (),
+.BR fmodf (),
+.BR fmodl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH BUGS
+Before glibc 2.10, the glibc implementation did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6784
+.I errno
+to
+.B EDOM
+when a domain error occurred for an infinite
+.IR x .
+.SH EXAMPLES
+The call
+.I fmod(372, 360)
+returns 348.
+.P
+The call
+.I fmod(-372, 360)
+returns -12.
+.P
+The call
+.I fmod(-372, -360)
+also returns -12.
+.SH SEE ALSO
+.BR remainder (3)
diff --git a/man/man3/fmodf.3 b/man/man3/fmodf.3
new file mode 100644
index 000000000..d014cc043
--- /dev/null
+++ b/man/man3/fmodf.3
@@ -0,0 +1 @@
+.so man3/fmod.3
diff --git a/man/man3/fmodl.3 b/man/man3/fmodl.3
new file mode 100644
index 000000000..d014cc043
--- /dev/null
+++ b/man/man3/fmodl.3
@@ -0,0 +1 @@
+.so man3/fmod.3
diff --git a/man/man3/fmtmsg.3 b/man/man3/fmtmsg.3
new file mode 100644
index 000000000..699db65e7
--- /dev/null
+++ b/man/man3/fmtmsg.3
@@ -0,0 +1,337 @@
+'\" t
+.\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\"  adapted glibc info page
+.\"
+.\"  This should run as 'Guru Meditation' (amiga joke :)
+.\"  The function is quite complex and deserves an example
+.\"
+.\"  Polished, aeb, 2003-11-01
+.TH fmtmsg 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fmtmsg \- print formatted error messages
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <fmtmsg.h>
+.P
+.BI "int fmtmsg(long " classification ", const char *" label ,
+.BI "           int " severity ", const char *" text ,
+.BI "           const char *" action ", const char *" tag );
+.fi
+.SH DESCRIPTION
+This function displays a message described by its arguments on the device(s)
+specified in the
+.I classification
+argument.
+For messages written to
+.IR stderr ,
+the format depends on the
+.B MSGVERB
+environment variable.
+.P
+The
+.I label
+argument identifies the source of the message.
+The string must consist
+of two colon separated parts where the first part has not more
+than 10 and the second part not more than 14 characters.
+.P
+The
+.I text
+argument describes the condition of the error.
+.P
+The
+.I action
+argument describes possible steps to recover from the error.
+If it is printed, it is prefixed by "TO FIX: ".
+.P
+The
+.I tag
+argument is a reference to the online documentation where more
+information can be found.
+It should contain the
+.I label
+value and a unique identification number.
+.SS Dummy arguments
+Each of the arguments can have a dummy value.
+The dummy classification value
+.B MM_NULLMC
+(0L) does not specify any output, so nothing is printed.
+The dummy severity value
+.B NO_SEV
+(0) says that no severity is supplied.
+The values
+.BR MM_NULLLBL ,
+.BR MM_NULLTXT ,
+.BR MM_NULLACT ,
+.B MM_NULLTAG
+are synonyms for
+.IR "((char\ *)\ 0)" ,
+the empty string, and
+.B MM_NULLSEV
+is a synonym for
+.BR NO_SEV .
+.SS The classification argument
+The
+.I classification
+argument is the sum of values describing 4 types of information.
+.P
+The first value defines the output channel.
+.TP 12n
+.B MM_PRINT
+Output to
+.IR stderr .
+.TP
+.B MM_CONSOLE
+Output to the system console.
+.TP
+.B "MM_PRINT | MM_CONSOLE"
+Output to both.
+.P
+The second value is the source of the error:
+.TP 12n
+.B MM_HARD
+A hardware error occurred.
+.TP
+.B MM_FIRM
+A firmware error occurred.
+.TP
+.B MM_SOFT
+A software error occurred.
+.P
+The third value encodes the detector of the problem:
+.TP 12n
+.B MM_APPL
+It is detected by an application.
+.TP
+.B MM_UTIL
+It is detected by a utility.
+.TP
+.B MM_OPSYS
+It is detected by the operating system.
+.P
+The fourth value shows the severity of the incident:
+.TP 12n
+.B MM_RECOVER
+It is a recoverable error.
+.TP
+.B MM_NRECOV
+It is a nonrecoverable error.
+.SS The severity argument
+The
+.I severity
+argument can take one of the following values:
+.TP 12n
+.B MM_NOSEV
+No severity is printed.
+.TP
+.B MM_HALT
+This value is printed as HALT.
+.TP
+.B MM_ERROR
+This value is printed as ERROR.
+.TP
+.B MM_WARNING
+This value is printed as WARNING.
+.TP
+.B MM_INFO
+This value is printed as INFO.
+.P
+The numeric values are between 0 and 4.
+Using
+.BR addseverity (3)
+or the environment variable
+.B SEV_LEVEL
+you can add more levels and strings to print.
+.SH RETURN VALUE
+The function can return 4 values:
+.TP 12n
+.B MM_OK
+Everything went smooth.
+.TP
+.B MM_NOTOK
+Complete failure.
+.TP
+.B MM_NOMSG
+Error writing to
+.IR stderr .
+.TP
+.B MM_NOCON
+Error writing to the console.
+.SH ENVIRONMENT
+The environment variable
+.B MSGVERB
+("message verbosity") can be used to suppress parts of
+the output to
+.IR stderr .
+(It does not influence output to the console.)
+When this variable is defined, is non-NULL, and is a colon-separated
+list of valid keywords, then only the parts of the message corresponding
+to these keywords is printed.
+Valid keywords are "label", "severity", "text", "action", and "tag".
+.P
+The environment variable
+.B SEV_LEVEL
+can be used to introduce new severity levels.
+By default, only the five severity levels described
+above are available.
+Any other numeric value would make
+.BR fmtmsg ()
+print nothing.
+If the user puts
+.B SEV_LEVEL
+with a format like
+.P
+.RS
+SEV_LEVEL=[description[:description[:...]]]
+.RE
+.P
+in the environment of the process before the first call to
+.BR fmtmsg (),
+where each description is of the form
+.P
+.RS
+severity-keyword,level,printstring
+.RE
+.P
+then
+.BR fmtmsg ()
+will also accept the indicated values for the level (in addition to
+the standard levels 0\[en]4), and use the indicated printstring when
+such a level occurs.
+.P
+The severity-keyword part is not used by
+.BR fmtmsg ()
+but it has to be present.
+The level part is a string representation of a number.
+The numeric value must be a number greater than 4.
+This value must be used in the severity argument of
+.BR fmtmsg ()
+to select this class.
+It is not possible to overwrite
+any of the predefined classes.
+The printstring
+is the string printed when a message of this class is processed by
+.BR fmtmsg ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fmtmsg ()
+T}	Thread safety	T{
+.na
+.nh
+glibc\ >=\ 2.16: MT-Safe;
+glibc\ <\ 2.16: MT-Unsafe
+T}
+.TE
+.P
+Before glibc 2.16, the
+.BR fmtmsg ()
+function uses a static variable that is not protected,
+so it is not thread-safe.
+.P
+Since glibc 2.16,
+.\" Modified in commit 7724defcf8873116fe4efab256596861eef21a94
+the
+.BR fmtmsg ()
+function uses a lock to protect the static variable, so it is thread-safe.
+.SH STANDARDS
+.TP
+.BR fmtmsg ()
+.TQ
+.B MSGVERB
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR fmtmsg ()
+System V.
+POSIX.1-2001 and POSIX.1-2008.
+glibc 2.1.
+.TP
+.B MSGVERB
+System V.
+POSIX.1-2001 and POSIX.1-2008.
+.TP
+.B SEV_LEVEL
+System V.
+.P
+System V and UnixWare man pages tell us that these functions
+have been replaced by "pfmt() and addsev()" or by "pfmt(),
+vpfmt(), lfmt(), and vlfmt()", and will be removed later.
+.SH EXAMPLES
+.\" SRC BEGIN (fmtmsg.c)
+.EX
+#include <fmtmsg.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    long class = MM_PRINT | MM_SOFT | MM_OPSYS | MM_RECOVER;
+    int err;
+\&
+    err = fmtmsg(class, "util\-linux:mount", MM_ERROR,
+                 "unknown mount option", "See mount(8).",
+                 "util\-linux:mount:017");
+    switch (err) {
+    case MM_OK:
+        break;
+    case MM_NOTOK:
+        printf("Nothing printed\en");
+        break;
+    case MM_NOMSG:
+        printf("Nothing printed to stderr\en");
+        break;
+    case MM_NOCON:
+        printf("No console output\en");
+        break;
+    default:
+        printf("Unknown error from fmtmsg()\en");
+    }
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.P
+The output should be:
+.P
+.in +4n
+.EX
+util\-linux:mount: ERROR: unknown mount option
+TO FIX: See mount(8).  util\-linux:mount:017
+.EE
+.in
+.P
+and after
+.P
+.in +4n
+.EX
+MSGVERB=text:action; export MSGVERB
+.EE
+.in
+.P
+the output becomes:
+.P
+.in +4n
+.EX
+unknown mount option
+TO FIX: See mount(8).
+.EE
+.in
+.SH SEE ALSO
+.BR addseverity (3),
+.BR perror (3)
diff --git a/man/man3/fnmatch.3 b/man/man3/fnmatch.3
new file mode 100644
index 000000000..978163af5
--- /dev/null
+++ b/man/man3/fnmatch.3
@@ -0,0 +1,141 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 19:35:54 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon Oct 16 00:16:29 2000 following Joseph S. Myers
+.\"
+.TH fnmatch 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fnmatch \- match filename or pathname
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <fnmatch.h>
+.P
+.BI "int fnmatch(const char *" "pattern" ", const char *" string ", int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR fnmatch ()
+function checks whether the
+.I string
+argument matches the
+.I pattern
+argument, which is a shell wildcard pattern (see
+.BR glob (7)).
+.P
+The
+.I flags
+argument modifies the behavior; it is the bitwise OR of zero or more
+of the following flags:
+.TP
+.B FNM_NOESCAPE
+If this flag is set, treat backslash as an ordinary character,
+instead of an escape character.
+.TP
+.B FNM_PATHNAME
+If this flag is set, match a slash in
+.I string
+only with a slash in
+.I pattern
+and not by an asterisk (*) or a question mark (?) metacharacter,
+nor by a bracket expression ([]) containing a slash.
+.TP
+.B FNM_PERIOD
+If this flag is set, a leading period in
+.I string
+has to be matched exactly by a period in
+.IR pattern .
+A period is considered to be leading if it is the first character in
+.IR string ,
+or if both
+.B FNM_PATHNAME
+is set and the period immediately follows a slash.
+.TP
+.B FNM_FILE_NAME
+This is a GNU synonym for
+.BR FNM_PATHNAME .
+.TP
+.B FNM_LEADING_DIR
+If this flag (a GNU extension) is set, the pattern is considered to be
+matched if it matches an initial segment of
+.I string
+which is followed by a slash.
+This flag is mainly for the internal
+use of glibc and is implemented only in certain cases.
+.TP
+.B FNM_CASEFOLD
+If this flag (a GNU extension) is set, the pattern is matched
+case-insensitively.
+.TP
+.B FNM_EXTMATCH
+If this flag (a GNU extension) is set, extended patterns are
+supported, as introduced by \&'ksh' and now supported by other shells.
+The extended format is as follows, with \fIpattern\-list\fR
+being a \&'|' separated list of patterns.
+.TP
+\&'?(\fIpattern\-list\fR)'
+The pattern matches if zero or one occurrences of any of the
+patterns in the \fIpattern\-list\fR match the input \fIstring\fR.
+.TP
+\&'*(\fIpattern\-list\fR)'
+The pattern matches if zero or more occurrences of any of the
+patterns in the \fIpattern\-list\fR match the input \fIstring\fR.
+.TP
+\&'+(\fIpattern\-list\fR)'
+The pattern matches if one or more occurrences of any of the
+patterns in the \fIpattern\-list\fR match the input \fIstring\fR.
+.TP
+\&'@(\fIpattern\-list\fR)'
+The pattern matches if exactly one occurrence of any of the
+patterns in the \fIpattern\-list\fR match the input \fIstring\fR.
+.TP
+\&'!(\fIpattern\-list\fR)'
+The pattern matches if the input \fIstring\fR cannot be matched with
+any of the patterns in the \fIpattern\-list\fR.
+.SH RETURN VALUE
+Zero if
+.I string
+matches
+.IR pattern ,
+.B FNM_NOMATCH
+if there is no match or another nonzero value if there is an error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fnmatch ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+.TP
+.BR fnmatch ()
+POSIX.1-2008.
+.TP
+.B FNM_FILE_NAME
+.TQ
+.B FNM_LEADING_DIR
+.TQ
+.B FNM_CASEFOLD
+GNU.
+.SH HISTORY
+.TP
+.BR fnmatch ()
+POSIX.1-2001, POSIX.2.
+.SH SEE ALSO
+.BR sh (1),
+.BR glob (3),
+.BR scandir (3),
+.BR wordexp (3),
+.BR glob (7)
diff --git a/man/man3/fopen.3 b/man/man3/fopen.3
new file mode 100644
index 000000000..4e230a8fd
--- /dev/null
+++ b/man/man3/fopen.3
@@ -0,0 +1,405 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)fopen.3	6.8 (Berkeley) 6/29/91
+.\"
+.\" Converted for Linux, Mon Nov 29 15:22:01 1993, faith@cs.unc.edu
+.\" Modified, aeb, 960421, 970806
+.\" Modified, joey, aeb, 2002-01-03
+.\"
+.TH fopen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fopen, fdopen, freopen \- stream open functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "FILE *fopen(const char *restrict " pathname \
+", const char *restrict " mode );
+.BI "FILE *fdopen(int " fd ", const char *" mode );
+.BI "FILE *freopen(const char *restrict " pathname \
+", const char *restrict " mode ,
+.BI "              FILE *restrict " stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fdopen ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR fopen ()
+function opens the file whose name is the string pointed to by
+.I pathname
+and associates a stream with it.
+.P
+The argument
+.I mode
+points to a string beginning with one of the following sequences
+(possibly followed by additional characters, as described below):
+.TP
+.B r
+Open text file for reading.
+The stream is positioned at the beginning of the file.
+.TP
+.B r+
+Open for reading and writing.
+The stream is positioned at the beginning of the file.
+.TP
+.B w
+Truncate file to zero length or create text file for writing.
+The stream is positioned at the beginning of the file.
+.TP
+.B w+
+Open for reading and writing.
+The file is created if it does not exist, otherwise it is truncated.
+The stream is positioned at the beginning of
+the file.
+.TP
+.B a
+Open for appending (writing at end of file).
+The file is created if it does not exist.
+The stream is positioned at the end of the file.
+.TP
+.B a+
+Open for reading and appending (writing at end of file).
+The file is created if it does not exist.
+Output is always appended to the end of the file.
+POSIX is silent on what the initial read position is when using this mode.
+For glibc, the initial file position for reading is at
+the beginning of the file, but for Android/BSD/MacOS, the
+initial file position for reading is at the end of the file.
+.P
+The
+.I mode
+string can also include the letter \[aq]b\[aq] either as a last character or as
+a character between the characters in any of the two-character strings
+described above.
+This is strictly for compatibility with ISO C
+and has no effect; the \[aq]b\[aq] is ignored on all POSIX
+conforming systems, including Linux.
+(Other systems may treat text files and binary files differently,
+and adding the \[aq]b\[aq] may be a good idea if you do I/O to a binary
+file and expect that your program may be ported to non-UNIX
+environments.)
+.P
+See NOTES below for details of glibc extensions for
+.IR mode .
+.P
+Any created file will have the mode
+.BR S_IRUSR " | " S_IWUSR " | "  S_IRGRP " | "  S_IWGRP " | " S_IROTH " | " S_IWOTH
+(0666), as modified by the process's umask value (see
+.BR umask (2)).
+.P
+Reads and writes may be intermixed on read/write streams in any order.
+Note that ANSI C requires that a file positioning function intervene
+between output and input, unless an input operation encounters end-of-file.
+(If this condition is not met, then a read is allowed to return the
+result of writes other than the most recent.)
+Therefore it is good practice (and indeed sometimes necessary
+under Linux) to put an
+.BR fseek (3)
+or
+.BR fsetpos (3)
+operation between write and read operations on such a stream.
+This operation may be an apparent no-op
+(as in \fIfseek(..., 0L, SEEK_CUR)\fP
+called for its synchronizing side effect).
+.P
+Opening a file in append mode (\fBa\fP as the first character of
+.IR mode )
+causes all subsequent write operations to this stream to occur
+at end-of-file, as if preceded by the call:
+.P
+.in +4n
+.EX
+fseek(stream, 0, SEEK_END);
+.EE
+.in
+.P
+The file descriptor associated with the stream is opened as if by a call to
+.BR open (2)
+with the following flags:
+.RS
+.TS
+allbox;
+lb lb
+c l.
+fopen() mode	open() flags
+\fIr\fP	O_RDONLY
+\fIw\fP	O_WRONLY | O_CREAT | O_TRUNC
+\fIa\fP	O_WRONLY | O_CREAT | O_APPEND
+\fIr+\fP	O_RDWR
+\fIw+\fP	O_RDWR | O_CREAT | O_TRUNC
+\fIa+\fP	O_RDWR | O_CREAT | O_APPEND
+.TE
+.RE
+.\"
+.SS fdopen()
+The
+.BR fdopen ()
+function associates a stream with the existing file descriptor,
+.IR fd .
+The
+.I mode
+of the stream (one of the values "r", "r+", "w", "w+", "a", "a+")
+must be compatible with the mode of the file descriptor.
+The file position indicator of the new stream is set to that
+belonging to
+.IR fd ,
+and the error and end-of-file indicators are cleared.
+Modes "w" or "w+" do not cause truncation of the file.
+The file descriptor is not dup'ed, and will be closed when
+the stream created by
+.BR fdopen ()
+is closed.
+The result of applying
+.BR fdopen ()
+to a shared memory object is undefined.
+.\"
+.SS freopen()
+The
+.BR freopen ()
+function opens the file whose name is the string pointed to by
+.I pathname
+and associates the stream pointed to by
+.I stream
+with it.
+The original stream (if it exists) is closed.
+The
+.I mode
+argument is used just as in the
+.BR fopen ()
+function.
+.P
+If the
+.I pathname
+argument is a null pointer,
+.BR freopen ()
+changes the mode of the stream to that specified in
+.IR mode ;
+that is,
+.BR freopen ()
+reopens the pathname that is associated with the stream.
+The specification for this behavior was added in the C99 standard, which says:
+.P
+.RS
+In this case,
+the file descriptor associated with the stream need not be closed
+if the call to
+.BR freopen ()
+succeeds.
+It is implementation-defined which changes of mode are permitted (if any),
+and under what circumstances.
+.RE
+.P
+The primary use of the
+.BR freopen ()
+function is to change the file associated with a standard text stream
+.RI ( stderr ", " stdin ", or " stdout ).
+.SH RETURN VALUE
+Upon successful completion
+.BR fopen (),
+.BR fdopen (),
+and
+.BR freopen ()
+return a
+.I FILE
+pointer.
+Otherwise, NULL is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The
+.I mode
+provided to
+.BR fopen (),
+.BR fdopen (),
+or
+.BR freopen ()
+was invalid.
+.P
+The
+.BR fopen (),
+.BR fdopen (),
+and
+.BR freopen ()
+functions may also fail and set
+.I errno
+for any of the errors specified for the routine
+.BR malloc (3).
+.P
+The
+.BR fopen ()
+function may also fail and set
+.I errno
+for any of the errors specified for the routine
+.BR open (2).
+.P
+The
+.BR fdopen ()
+function may also fail and set
+.I errno
+for any of the errors specified for the routine
+.BR fcntl (2).
+.P
+The
+.BR freopen ()
+function may also fail and set
+.I errno
+for any of the errors specified for the routines
+.BR open (2),
+.BR fclose (3),
+and
+.BR fflush (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fopen (),
+.BR fdopen (),
+.BR freopen ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR fopen ()
+.TQ
+.BR freopen ()
+C11, POSIX.1-2008.
+.TP
+.BR fdopen ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR fopen ()
+.TQ
+.BR freopen ()
+POSIX.1-2001, C89.
+.TP
+.BR fdopen ()
+POSIX.1-2001.
+.SH NOTES
+.SS glibc notes
+The GNU C library allows the following extensions for the string specified in
+.IR mode :
+.TP
+.BR c " (since glibc 2.3.3)"
+Do not make the open operation,
+or subsequent read and write operations,
+thread cancelation points.
+This flag is ignored for
+.BR fdopen ().
+.TP
+.BR e " (since glibc 2.7)"
+Open the file with the
+.B O_CLOEXEC
+flag.
+See
+.BR open (2)
+for more information.
+This flag is ignored for
+.BR fdopen ().
+.TP
+.BR m " (since glibc 2.3)"
+Attempt to access the file using
+.BR mmap (2),
+rather than I/O system calls
+.RB ( read (2),
+.BR write (2)).
+Currently,
+.\" As at glibc 2.4:
+use of
+.BR mmap (2)
+is attempted only for a file opened for reading.
+.TP
+.B x
+.\" Since glibc 2.0?
+.\" FIXME . C11 specifies this flag
+Open the file exclusively
+(like the
+.B O_EXCL
+flag of
+.BR open (2)).
+If the file already exists,
+.BR fopen ()
+fails, and sets
+.I errno
+to
+.BR EEXIST .
+This flag is ignored for
+.BR fdopen ().
+.P
+In addition to the above characters,
+.BR fopen ()
+and
+.BR freopen ()
+support the following syntax
+in
+.IR mode :
+.P
+.BI "    ,ccs=" string
+.P
+The given
+.I string
+is taken as the name of a coded character set and
+the stream is marked as wide-oriented.
+Thereafter, internal conversion functions convert I/O
+to and from the character set
+.IR string .
+If the
+.BI ,ccs= string
+syntax is not specified,
+then the wide-orientation of the stream is
+determined by the first file operation.
+If that operation is a wide-character operation,
+the stream is marked wide-oriented,
+and functions to convert to the coded character set are loaded.
+.SH BUGS
+When parsing for individual flag characters in
+.I mode
+(i.e., the characters preceding the "ccs" specification),
+the glibc implementation of
+.\" FIXME . http://sourceware.org/bugzilla/show_bug.cgi?id=12685
+.BR fopen ()
+and
+.BR freopen ()
+limits the number of characters examined in
+.I mode
+to 7 (or, before glibc 2.14, to 6,
+which was not enough to include possible specifications such as "rb+cmxe").
+The current implementation of
+.BR fdopen ()
+parses at most 5 characters in
+.IR mode .
+.SH SEE ALSO
+.BR open (2),
+.BR fclose (3),
+.BR fileno (3),
+.BR fmemopen (3),
+.BR fopencookie (3),
+.BR open_memstream (3)
diff --git a/man/man3/fopencookie.3 b/man/man3/fopencookie.3
new file mode 100644
index 000000000..d1821772c
--- /dev/null
+++ b/man/man3/fopencookie.3
@@ -0,0 +1,466 @@
+'\" t
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"      <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH fopencookie 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fopencookie \- open a custom stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #define _FILE_OFFSET_BITS 64
+.B #include <stdio.h>
+.P
+.BI "FILE *fopencookie(void *restrict " cookie ", const char *restrict " mode ,
+.BI "                  cookie_io_functions_t " io_funcs );
+.fi
+.SH DESCRIPTION
+The
+.BR fopencookie ()
+function allows the programmer to create a custom implementation
+for a standard I/O stream.
+This implementation can store the stream's data at a location of
+its own choosing; for example,
+.BR fopencookie ()
+is used to implement
+.BR fmemopen (3),
+which provides a stream interface to data that is stored in a
+buffer in memory.
+.P
+In order to create a custom stream the programmer must:
+.IP \[bu] 3
+Implement four "hook" functions that are used internally by the
+standard I/O library when performing I/O on the stream.
+.IP \[bu]
+Define a "cookie" data type,
+a structure that provides bookkeeping information
+(e.g., where to store data) used by the aforementioned hook functions.
+The standard I/O package knows nothing about the contents of this cookie
+(thus it is typed as
+.I void\~*
+when passed to
+.BR fopencookie ()),
+but automatically supplies the cookie
+as the first argument when calling the hook functions.
+.IP \[bu]
+Call
+.BR fopencookie ()
+to open a new stream and associate the cookie and hook functions
+with that stream.
+.P
+The
+.BR fopencookie ()
+function serves a purpose similar to
+.BR fopen (3):
+it opens a new stream and returns a pointer to a
+.I FILE
+object that is used to operate on that stream.
+.P
+The
+.I cookie
+argument is a pointer to the caller's cookie structure
+that is to be associated with the new stream.
+This pointer is supplied as the first argument when the standard I/O
+library invokes any of the hook functions described below.
+.P
+The
+.I mode
+argument serves the same purpose as for
+.BR fopen (3).
+The following modes are supported:
+.IR r ,
+.IR w ,
+.IR a ,
+.IR r+ ,
+.IR w+ ,
+and
+.IR a+ .
+See
+.BR fopen (3)
+for details.
+.P
+The
+.I io_funcs
+argument is a structure that contains four fields pointing to the
+programmer-defined hook functions that are used to implement this stream.
+The structure is defined as follows
+.P
+.in +4n
+.EX
+typedef struct {
+    cookie_read_function_t  *read;
+    cookie_write_function_t *write;
+    cookie_seek_function_t  *seek;
+    cookie_close_function_t *close;
+} cookie_io_functions_t;
+.EE
+.in
+.P
+The four fields are as follows:
+.TP
+.I cookie_read_function_t *read
+This function implements read operations for the stream.
+When called, it receives three arguments:
+.IP
+.in +4n
+.EX
+ssize_t read(void *cookie, char *buf, size_t size);
+.EE
+.in
+.IP
+The
+.I buf
+and
+.I size
+arguments are, respectively,
+a buffer into which input data can be placed and the size of that buffer.
+As its function result, the
+.I read
+function should return the number of bytes copied into
+.IR buf ,
+0 on end of file, or \-1 on error.
+The
+.I read
+function should update the stream offset appropriately.
+.IP
+If
+.I *read
+is a null pointer,
+then reads from the custom stream always return end of file.
+.TP
+.I cookie_write_function_t *write
+This function implements write operations for the stream.
+When called, it receives three arguments:
+.IP
+.in +4n
+.EX
+ssize_t write(void *cookie, const char *buf, size_t size);
+.EE
+.in
+.IP
+The
+.I buf
+and
+.I size
+arguments are, respectively,
+a buffer of data to be output to the stream and the size of that buffer.
+As its function result, the
+.I write
+function should return the number of bytes copied from
+.IR buf ,
+or 0 on error.
+(The function must not return a negative value.)
+The
+.I write
+function should update the stream offset appropriately.
+.IP
+If
+.I *write
+is a null pointer,
+then output to the stream is discarded.
+.TP
+.I cookie_seek_function_t *seek
+This function implements seek operations on the stream.
+When called, it receives three arguments:
+.IP
+.in +4n
+.EX
+int seek(void *cookie, off_t *offset, int whence);
+.EE
+.in
+.IP
+The
+.I *offset
+argument specifies the new file offset depending on which
+of the following three values is supplied in
+.IR whence :
+.RS
+.TP
+.B SEEK_SET
+The stream offset should be set
+.I *offset
+bytes from the start of the stream.
+.TP
+.B SEEK_CUR
+.I *offset
+should be added to the current stream offset.
+.TP
+.B SEEK_END
+The stream offset should be set to the size of the stream plus
+.IR *offset .
+.RE
+.IP
+Before returning, the
+.I seek
+function should update
+.I *offset
+to indicate the new stream offset.
+.IP
+As its function result, the
+.I seek
+function should return 0 on success, and \-1 on error.
+.IP
+If
+.I *seek
+is a null pointer,
+then it is not possible to perform seek operations on the stream.
+.TP
+.I cookie_close_function_t *close
+This function closes the stream.
+The hook function can do things such as freeing buffers allocated
+for the stream.
+When called, it receives one argument:
+.IP
+.in +4n
+.EX
+int close(void *cookie);
+.EE
+.in
+.IP
+The
+.I cookie
+argument is the cookie that the programmer supplied when calling
+.BR fopencookie ().
+.IP
+As its function result, the
+.I close
+function should return 0 on success, and
+.B EOF
+on error.
+.IP
+If
+.I *close
+is NULL, then no special action is performed when the stream is closed.
+.SH RETURN VALUE
+On success
+.BR fopencookie ()
+returns a pointer to the new stream.
+On error, NULL is returned.
+.\" .SH ERRORS
+.\" It's not clear if errno ever gets set...
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fopencookie ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH EXAMPLES
+The program below implements a custom stream whose functionality
+is similar (but not identical) to that available via
+.BR fmemopen (3).
+It implements a stream whose data is stored in a memory buffer.
+The program writes its command-line arguments to the stream,
+and then seeks through the stream reading two out of every
+five characters and writing them to standard output.
+The following shell session demonstrates the use of the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \[aq]hello world\[aq]"
+/he/
+/ w/
+/d/
+Reached end of file
+.EE
+.in
+.P
+Note that a more general version of the program below
+could be improved to more robustly handle various error situations
+(e.g., opening a stream with a cookie that already has an open stream;
+closing a stream that has already been closed).
+.SS Program source
+\&
+.\" SRC BEGIN (fopencookie.c)
+.EX
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+\&
+#define INIT_BUF_SIZE 4
+\&
+struct memfile_cookie {
+    char   *buf;        /* Dynamically sized buffer for data */
+    size_t  allocated;  /* Size of buf */
+    size_t  endpos;     /* Number of characters in buf */
+    off_t   offset;     /* Current file offset in buf */
+};
+\&
+ssize_t
+memfile_write(void *c, const char *buf, size_t size)
+{
+    char *new_buff;
+    struct memfile_cookie *cookie = c;
+\&
+    /* Buffer too small? Keep doubling size until big enough. */
+\&
+    while (size + cookie\->offset > cookie\->allocated) {
+        new_buff = realloc(cookie\->buf, cookie\->allocated * 2);
+        if (new_buff == NULL)
+            return \-1;
+        cookie\->allocated *= 2;
+        cookie\->buf = new_buff;
+    }
+\&
+    memcpy(cookie\->buf + cookie\->offset, buf, size);
+\&
+    cookie\->offset += size;
+    if (cookie\->offset > cookie\->endpos)
+        cookie\->endpos = cookie\->offset;
+\&
+    return size;
+}
+\&
+ssize_t
+memfile_read(void *c, char *buf, size_t size)
+{
+    ssize_t xbytes;
+    struct memfile_cookie *cookie = c;
+\&
+    /* Fetch minimum of bytes requested and bytes available. */
+\&
+    xbytes = size;
+    if (cookie\->offset + size > cookie\->endpos)
+        xbytes = cookie\->endpos \- cookie\->offset;
+    if (xbytes < 0)     /* offset may be past endpos */
+        xbytes = 0;
+\&
+    memcpy(buf, cookie\->buf + cookie\->offset, xbytes);
+\&
+    cookie\->offset += xbytes;
+    return xbytes;
+}
+\&
+int
+memfile_seek(void *c, off_t *offset, int whence)
+{
+    off_t new_offset;
+    struct memfile_cookie *cookie = c;
+\&
+    if (whence == SEEK_SET)
+        new_offset = *offset;
+    else if (whence == SEEK_END)
+        new_offset = cookie\->endpos + *offset;
+    else if (whence == SEEK_CUR)
+        new_offset = cookie\->offset + *offset;
+    else
+        return \-1;
+\&
+    if (new_offset < 0)
+        return \-1;
+\&
+    cookie\->offset = new_offset;
+    *offset = new_offset;
+    return 0;
+}
+\&
+int
+memfile_close(void *c)
+{
+    struct memfile_cookie *cookie = c;
+\&
+    free(cookie\->buf);
+    cookie\->allocated = 0;
+    cookie\->buf = NULL;
+\&
+    return 0;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    cookie_io_functions_t  memfile_func = {
+        .read  = memfile_read,
+        .write = memfile_write,
+        .seek  = memfile_seek,
+        .close = memfile_close
+    };
+    FILE *stream;
+    struct memfile_cookie mycookie;
+    size_t nread;
+    char buf[1000];
+\&
+    /* Set up the cookie before calling fopencookie(). */
+\&
+    mycookie.buf = malloc(INIT_BUF_SIZE);
+    if (mycookie.buf == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    mycookie.allocated = INIT_BUF_SIZE;
+    mycookie.offset = 0;
+    mycookie.endpos = 0;
+\&
+    stream = fopencookie(&mycookie, "w+", memfile_func);
+    if (stream == NULL) {
+        perror("fopencookie");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Write command\-line arguments to our file. */
+\&
+    for (size_t j = 1; j < argc; j++)
+        if (fputs(argv[j], stream) == EOF) {
+            perror("fputs");
+            exit(EXIT_FAILURE);
+        }
+\&
+    /* Read two bytes out of every five, until EOF. */
+\&
+    for (long p = 0; ; p += 5) {
+        if (fseek(stream, p, SEEK_SET) == \-1) {
+            perror("fseek");
+            exit(EXIT_FAILURE);
+        }
+        nread = fread(buf, 1, 2, stream);
+        if (nread == 0) {
+            if (ferror(stream) != 0) {
+                fprintf(stderr, "fread failed\en");
+                exit(EXIT_FAILURE);
+            }
+            printf("Reached end of file\en");
+            break;
+        }
+\&
+        printf("/%.*s/\en", (int) nread, buf);
+    }
+\&
+    free(mycookie.buf);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH NOTES
+.B _FILE_OFFSET_BITS
+should be defined to be 64 in code that uses non-null
+.I seek
+or that takes the address of
+.BR fopencookie ,
+if the code is intended to be portable
+to traditional 32-bit x86 and ARM platforms where
+.BR off_t 's
+width defaults to 32 bits.
+.SH SEE ALSO
+.BR fclose (3),
+.BR fmemopen (3),
+.BR fopen (3),
+.BR fseek (3)
diff --git a/man/man3/forkpty.3 b/man/man3/forkpty.3
new file mode 100644
index 000000000..fb4952d52
--- /dev/null
+++ b/man/man3/forkpty.3
@@ -0,0 +1 @@
+.so man3/openpty.3
diff --git a/man/man3/fpathconf.3 b/man/man3/fpathconf.3
new file mode 100644
index 000000000..7718473c3
--- /dev/null
+++ b/man/man3/fpathconf.3
@@ -0,0 +1,273 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright (C) 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 28 11:12:26 1993 by Rik Faith (faith@cs.unc.edu)
+.\"
+.\" FIXME Probably all of the following should be documented:
+.\"     _PC_SYNC_IO,
+.\"     _PC_ASYNC_IO,
+.\"     _PC_PRIO_IO,
+.\"     _PC_SOCK_MAXBUF,
+.\"     _PC_FILESIZEBITS,
+.\"     _PC_REC_INCR_XFER_SIZE,
+.\"     _PC_REC_MAX_XFER_SIZE,
+.\"     _PC_REC_MIN_XFER_SIZE,
+.\"     _PC_REC_XFER_ALIGN,
+.\"     _PC_ALLOC_SIZE_MIN,
+.\"     _PC_SYMLINK_MAX,
+.\"     _PC_2_SYMLINKS
+.\"
+.TH fpathconf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fpathconf, pathconf \- get configuration values for files
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "long fpathconf(int " fd ", int " name );
+.BI "long pathconf(const char *" path ", int " name );
+.fi
+.SH DESCRIPTION
+.BR fpathconf ()
+gets a value for the configuration option
+.I name
+for the open file descriptor
+.IR fd .
+.P
+.BR pathconf ()
+gets a value for configuration option
+.I name
+for the filename
+.IR path .
+.P
+The corresponding macros defined in
+.I <unistd.h>
+are minimum values; if an application wants to take advantage of values
+which may change, a call to
+.BR fpathconf ()
+or
+.BR pathconf ()
+can be made, which may yield more liberal results.
+.P
+Setting
+.I name
+equal to one of the following constants returns the following
+configuration options:
+.TP
+.B _PC_LINK_MAX
+The maximum number of links to the file.
+If
+.I fd
+or
+.I path
+refer to a directory, then the value applies to the whole directory.
+The corresponding macro is
+.BR _POSIX_LINK_MAX .
+.TP
+.B _PC_MAX_CANON
+The maximum length of a formatted input line, where
+.I fd
+or
+.I path
+must refer to a terminal.
+The corresponding macro is
+.BR _POSIX_MAX_CANON .
+.TP
+.B _PC_MAX_INPUT
+The maximum length of an input line, where
+.I fd
+or
+.I path
+must refer to a terminal.
+The corresponding macro is
+.BR _POSIX_MAX_INPUT .
+.TP
+.B _PC_NAME_MAX
+The maximum length of a filename in the directory
+.I path
+or
+.I fd
+that the process is allowed to create.
+The corresponding macro is
+.BR _POSIX_NAME_MAX .
+.TP
+.B _PC_PATH_MAX
+The maximum length of a relative pathname when
+.I path
+or
+.I fd
+is the current working directory.
+The corresponding macro is
+.BR _POSIX_PATH_MAX .
+.TP
+.B _PC_PIPE_BUF
+The maximum number of bytes that can be written atomically to a pipe of FIFO.
+For
+.BR fpathconf (),
+.I fd
+should refer to a pipe or FIFO.
+For
+.BR fpathconf (),
+.I path
+should refer to a FIFO or a directory; in the latter case,
+the returned value corresponds to FIFOs created in that directory.
+The corresponding macro is
+.BR _POSIX_PIPE_BUF .
+.TP
+.B _PC_CHOWN_RESTRICTED
+This returns a positive value if the use of
+.BR chown (2)
+and
+.BR fchown (2)
+for changing a file's user ID is restricted to a process
+with appropriate privileges,
+and changing a file's group ID to a value other than the process's
+effective group ID or one of its supplementary group IDs
+is restricted to a process with appropriate privileges.
+According to POSIX.1,
+this variable shall always be defined with a value other than \-1.
+The corresponding macro is
+.BR _POSIX_CHOWN_RESTRICTED .
+.IP
+If
+.I fd
+or
+.I path
+refers to a directory,
+then the return value applies to all files in that directory.
+.TP
+.B _PC_NO_TRUNC
+This returns nonzero if accessing filenames longer than
+.B _POSIX_NAME_MAX
+generates an error.
+The corresponding macro is
+.BR _POSIX_NO_TRUNC .
+.TP
+.B _PC_VDISABLE
+This returns nonzero if special character processing can be disabled, where
+.I fd
+or
+.I path
+must refer to a terminal.
+.SH RETURN VALUE
+The return value of these functions is one of the following:
+.IP \[bu] 3
+On error, \-1 is returned and
+.I errno
+is set to indicate the error
+(for example,
+.BR EINVAL ,
+indicating that
+.I name
+is invalid).
+.IP \[bu]
+If
+.I name
+corresponds to a maximum or minimum limit, and that limit is indeterminate,
+\-1 is returned and
+.I errno
+is not changed.
+(To distinguish an indeterminate limit from an error, set
+.I errno
+to zero before the call, and then check whether
+.I errno
+is nonzero when \-1 is returned.)
+.IP \[bu]
+If
+.I name
+corresponds to an option,
+a positive value is returned if the option is supported,
+and \-1 is returned if the option is not supported.
+.IP \[bu]
+Otherwise,
+the current value of the option or limit is returned.
+This value will not be more restrictive than
+the corresponding value that was described to the application in
+.I <unistd.h>
+or
+.I <limits.h>
+when the application was compiled.
+.SH ERRORS
+.TP
+.B EACCES
+.RB ( pathconf ())
+Search permission is denied for one of the directories in the path prefix of
+.IR path .
+.TP
+.B EBADF
+.RB ( fpathconf ())
+.I fd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+.I name
+is invalid.
+.TP
+.B EINVAL
+The implementation does not support an association of
+.I name
+with the specified file.
+.TP
+.B ELOOP
+.RB ( pathconf ())
+Too many symbolic links were encountered while resolving
+.IR path .
+.TP
+.B ENAMETOOLONG
+.RB ( pathconf ())
+.I path
+is too long.
+.TP
+.B ENOENT
+.RB ( pathconf ())
+A component of
+.I path
+does not exist, or
+.I path
+is an empty string.
+.TP
+.B ENOTDIR
+.RB ( pathconf ())
+A component used as a directory in
+.I path
+is not in fact a directory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fpathconf (),
+.BR pathconf ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+Files with name lengths longer than the value returned for
+.I name
+equal to
+.B _PC_NAME_MAX
+may exist in the given directory.
+.P
+Some returned values may be huge; they are not suitable for allocating
+memory.
+.SH SEE ALSO
+.BR getconf (1),
+.BR open (2),
+.BR statfs (2),
+.BR confstr (3),
+.BR sysconf (3)
diff --git a/man/man3/fpclassify.3 b/man/man3/fpclassify.3
new file mode 100644
index 000000000..98ec33d19
--- /dev/null
+++ b/man/man3/fpclassify.3
@@ -0,0 +1,145 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" This was done with the help of the glibc manual.
+.\"
+.\" 2004-10-31, aeb, corrected
+.TH fpclassify 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fpclassify, isfinite, isnormal, isnan, isinf \- floating-point
+classification macros
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "int fpclassify(" x );
+.BI "int isfinite(" x );
+.BI "int isnormal(" x );
+.BI "int isnan(" x );
+.BI "int isinf(" x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.\" I haven't fully grokked the source to determine the FTM requirements;
+.\" in part, the following has been tested by experiment.
+.BR fpclassify (),
+.BR isfinite (),
+.BR isnormal ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.P
+.BR isnan ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR isinf ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+Floating point numbers can have special values, such as
+infinite or NaN.
+With the macro
+.BI fpclassify( x )
+you can find out what type
+.I x
+is.
+The macro takes any floating-point expression as argument.
+The result is one of the following values:
+.TP 14
+.B FP_NAN
+.I x
+is "Not a Number".
+.TP
+.B FP_INFINITE
+.I x
+is either positive infinity or negative infinity.
+.TP
+.B FP_ZERO
+.I x
+is zero.
+.TP
+.B FP_SUBNORMAL
+.I x
+is too small to be represented in normalized format.
+.TP
+.B FP_NORMAL
+if nothing of the above is correct then it must be a
+normal floating-point number.
+.P
+The other macros provide a short answer to some standard questions.
+.TP 14
+.BI isfinite( x )
+returns a nonzero value if
+.br
+(fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
+.TP
+.BI isnormal( x )
+returns a nonzero value if
+(fpclassify(x) == FP_NORMAL)
+.TP
+.BI isnan( x )
+returns a nonzero value if
+(fpclassify(x) == FP_NAN)
+.TP
+.BI isinf( x )
+returns 1 if
+.I x
+is positive infinity, and \-1 if
+.I x
+is negative infinity.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fpclassify (),
+.BR isfinite (),
+.BR isnormal (),
+.BR isnan (),
+.BR isinf ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.P
+In glibc 2.01 and earlier,
+.BR isinf ()
+returns a nonzero value (actually: 1) if
+.I x
+is positive infinity or negative infinity.
+(This is all that C99 requires.)
+.SH NOTES
+For
+.BR isinf (),
+the standards merely say that the return value is nonzero
+if and only if the argument has an infinite value.
+.SH SEE ALSO
+.BR finite (3),
+.BR INFINITY (3),
+.BR isgreater (3),
+.BR signbit (3)
diff --git a/man/man3/fprintf.3 b/man/man3/fprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/fprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/fpurge.3 b/man/man3/fpurge.3
new file mode 100644
index 000000000..8b928f5f3
--- /dev/null
+++ b/man/man3/fpurge.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH fpurge 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fpurge, __fpurge \- purge a stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+/* unsupported */
+.B #include <stdio.h>
+.P
+.BI "int fpurge(FILE *" stream );
+.P
+/* supported */
+.B #include <stdio.h>
+.B #include <stdio_ext.h>
+.P
+.BI "void  __fpurge(FILE *" stream );
+.fi
+.SH DESCRIPTION
+The function
+.BR fpurge ()
+clears the buffers of the given stream.
+For output streams this discards any unwritten output.
+For input streams this discards any input read from the underlying object
+but not yet obtained via
+.BR getc (3);
+this includes any text pushed back via
+.BR ungetc (3).
+See also
+.BR fflush (3).
+.P
+The function
+.BR __fpurge ()
+does precisely the same, but without returning a value.
+.SH RETURN VALUE
+Upon successful completion
+.BR fpurge ()
+returns 0.
+On error, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I stream
+is not an open stream.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR __fpurge ()
+T}	Thread safety	MT-Safe race:stream
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+.TP
+.BR fpurge ()
+4.4BSD.
+Not available under Linux.
+.TP
+.BR __fpurge ()
+Solaris, glibc 2.1.95.
+.SH NOTES
+Usually it is a mistake to want to discard input buffers.
+.SH SEE ALSO
+.\" .BR fclean (3),
+.BR fflush (3),
+.BR setbuf (3),
+.BR stdio_ext (3)
diff --git a/man/man3/fputc.3 b/man/man3/fputc.3
new file mode 100644
index 000000000..a7c3b57fc
--- /dev/null
+++ b/man/man3/fputc.3
@@ -0,0 +1 @@
+.so man3/puts.3
diff --git a/man/man3/fputc_unlocked.3 b/man/man3/fputc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fputc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fputs.3 b/man/man3/fputs.3
new file mode 100644
index 000000000..a7c3b57fc
--- /dev/null
+++ b/man/man3/fputs.3
@@ -0,0 +1 @@
+.so man3/puts.3
diff --git a/man/man3/fputs_unlocked.3 b/man/man3/fputs_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fputs_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fputwc.3 b/man/man3/fputwc.3
new file mode 100644
index 000000000..3c7d4013b
--- /dev/null
+++ b/man/man3/fputwc.3
@@ -0,0 +1,104 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH fputwc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fputwc, putwc \- write a wide character to a FILE stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <wchar.h>
+.P
+.BI "wint_t fputwc(wchar_t " wc ", FILE *" stream );
+.BI "wint_t putwc(wchar_t " wc ", FILE *" stream );
+.fi
+.SH DESCRIPTION
+The
+.BR fputwc ()
+function is the wide-character
+equivalent of the
+.BR fputc (3)
+function.
+It writes the wide character \fIwc\fP to \fIstream\fP.
+If
+\fIferror(stream)\fP becomes true, it returns
+.BR WEOF .
+If a wide-character conversion error occurs,
+it sets \fIerrno\fP to \fBEILSEQ\fP and returns
+.BR WEOF .
+Otherwise, it returns \fIwc\fP.
+.P
+The
+.BR putwc ()
+function or macro functions identically to
+.BR fputwc ().
+It may be implemented as a macro, and may evaluate its argument
+more than once.
+There is no reason ever to use it.
+.P
+For nonlocking counterparts, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+On success,
+.BR fputwc ()
+function returns
+.IR wc .
+Otherwise,
+.B WEOF
+is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Apart from the usual ones, there is
+.TP
+.B EILSEQ
+Conversion of \fIwc\fP to the stream's encoding fails.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fputwc (),
+.BR putwc ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH NOTES
+The behavior of
+.BR fputwc ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+In the absence of additional information passed to the
+.BR fopen (3)
+call, it is
+reasonable to expect that
+.BR fputwc ()
+will actually write the multibyte
+sequence corresponding to the wide character \fIwc\fP.
+.SH SEE ALSO
+.BR fgetwc (3),
+.BR fputws (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/fputwc_unlocked.3 b/man/man3/fputwc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fputwc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fputws.3 b/man/man3/fputws.3
new file mode 100644
index 000000000..e40396d15
--- /dev/null
+++ b/man/man3/fputws.3
@@ -0,0 +1,78 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH fputws 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fputws \- write a wide-character string to a FILE stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int fputws(const wchar_t *restrict " ws ", FILE *restrict " stream );
+.fi
+.SH DESCRIPTION
+The
+.BR fputws ()
+function is the wide-character equivalent of
+the
+.BR fputs (3)
+function.
+It writes the wide-character string starting at \fIws\fP,
+up to but not including the terminating null wide character (L\[aq]\e0\[aq]),
+to \fIstream\fP.
+.P
+For a nonlocking counterpart, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+The
+.BR fputws ()
+function returns a
+nonnegative integer if the operation was
+successful, or \-1 to indicate an error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fputws ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR fputws ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+In the absence of additional information passed to the
+.BR fopen (3)
+call, it is
+reasonable to expect that
+.BR fputws ()
+will actually write the multibyte
+string corresponding to the wide-character string \fIws\fP.
+.SH SEE ALSO
+.BR fputwc (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/fputws_unlocked.3 b/man/man3/fputws_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fputws_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/fread.3 b/man/man3/fread.3
new file mode 100644
index 000000000..dc320cd30
--- /dev/null
+++ b/man/man3/fread.3
@@ -0,0 +1,164 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" and Copyright (c) 2020 Arkadiusz Drabczyk <arkadiusz@drabczyk.org>
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)fread.3	6.6 (Berkeley) 6/29/91
+.\"
+.\" Converted for Linux, Mon Nov 29 15:37:33 1993, faith@cs.unc.edu
+.\" Sun Feb 19 21:26:54 1995 by faith, return values
+.\" Modified Thu Apr 20 20:43:53 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" Modified Fri May 17 10:21:51 1996 by Martin Schulze <joey@infodrom.north.de>
+.\"
+.TH fread 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fread, fwrite \- binary stream input/output
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "size_t fread(void " ptr "[restrict ." size " * ." nmemb ],
+.BI "             size_t " size ", size_t " nmemb ,
+.BI "             FILE *restrict " stream );
+.BI "size_t fwrite(const void " ptr "[restrict ." size " * ." nmemb ],
+.BI "             size_t " size ", size_t " nmemb ,
+.BI "             FILE *restrict " stream );
+.fi
+.SH DESCRIPTION
+The function
+.BR fread ()
+reads
+.I nmemb
+items of data, each
+.I size
+bytes long, from the stream pointed to by
+.IR stream ,
+storing them at the location given by
+.IR ptr .
+.P
+The function
+.BR fwrite ()
+writes
+.I nmemb
+items of data, each
+.I size
+bytes long, to the stream pointed to by
+.IR stream ,
+obtaining them from the location given by
+.IR ptr .
+.P
+For nonlocking counterparts, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+On success,
+.BR fread ()
+and
+.BR fwrite ()
+return the number of items read or written.
+This number equals the number of bytes transferred only when
+.I size
+is 1.
+If an error occurs, or the end of the file is reached,
+the return value is a short item count (or zero).
+.P
+The file position indicator for the stream is advanced by the number
+of bytes successfully read or written.
+.P
+.BR fread ()
+does not distinguish between end-of-file and error, and callers must use
+.BR feof (3)
+and
+.BR ferror (3)
+to determine which occurred.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fread (),
+.BR fwrite ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR fread ()
+by parsing /bin/sh ELF executable in binary mode and printing its
+magic and class:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+ELF magic: 0x7f454c46
+Class: 0x02
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (fread.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+\&
+int
+main(void)
+{
+    FILE           *fp;
+    size_t         ret;
+    unsigned char  buffer[4];
+\&
+    fp = fopen("/bin/sh", "rb");
+    if (!fp) {
+        perror("fopen");
+        return EXIT_FAILURE;
+    }
+\&
+    ret = fread(buffer, sizeof(*buffer), ARRAY_SIZE(buffer), fp);
+    if (ret != ARRAY_SIZE(buffer)) {
+        fprintf(stderr, "fread() failed: %zu\en", ret);
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("ELF magic: %#04x%02x%02x%02x\en", buffer[0], buffer[1],
+           buffer[2], buffer[3]);
+\&
+    ret = fread(buffer, 1, 1, fp);
+    if (ret != 1) {
+        fprintf(stderr, "fread() failed: %zu\en", ret);
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Class: %#04x\en", buffer[0]);
+\&
+    fclose(fp);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR read (2),
+.BR write (2),
+.BR feof (3),
+.BR ferror (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/fread_unlocked.3 b/man/man3/fread_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fread_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/free.3 b/man/man3/free.3
new file mode 100644
index 000000000..a4b9d4455
--- /dev/null
+++ b/man/man3/free.3
@@ -0,0 +1 @@
+.so man3/malloc.3
diff --git a/man/man3/freeaddrinfo.3 b/man/man3/freeaddrinfo.3
new file mode 100644
index 000000000..17f7236a7
--- /dev/null
+++ b/man/man3/freeaddrinfo.3
@@ -0,0 +1 @@
+.so man3/getaddrinfo.3
diff --git a/man/man3/freehostent.3 b/man/man3/freehostent.3
new file mode 100644
index 000000000..82e01df46
--- /dev/null
+++ b/man/man3/freehostent.3
@@ -0,0 +1 @@
+.so man3/getipnodebyname.3
diff --git a/man/man3/freeifaddrs.3 b/man/man3/freeifaddrs.3
new file mode 100644
index 000000000..38f977da6
--- /dev/null
+++ b/man/man3/freeifaddrs.3
@@ -0,0 +1 @@
+.so man3/getifaddrs.3
diff --git a/man/man3/freelocale.3 b/man/man3/freelocale.3
new file mode 100644
index 000000000..a4246c555
--- /dev/null
+++ b/man/man3/freelocale.3
@@ -0,0 +1 @@
+.so man3/newlocale.3
diff --git a/man/man3/freopen.3 b/man/man3/freopen.3
new file mode 100644
index 000000000..9a4012491
--- /dev/null
+++ b/man/man3/freopen.3
@@ -0,0 +1 @@
+.so man3/fopen.3
diff --git a/man/man3/frexp.3 b/man/man3/frexp.3
new file mode 100644
index 000000000..16ece267d
--- /dev/null
+++ b/man/man3/frexp.3
@@ -0,0 +1,141 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH frexp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+frexp, frexpf, frexpl \- convert floating-point number to fractional
+and integral components
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double frexp(double " x ", int *" exp );
+.BI "float frexpf(float " x ", int *" exp );
+.BI "long double frexpl(long double " x ", int *" exp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR frexpf (),
+.BR frexpl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions are used to split the number
+.I x
+into a
+normalized fraction and an exponent which is stored in
+.IR exp .
+.SH RETURN VALUE
+These functions return the normalized fraction.
+If the argument
+.I x
+is not zero,
+the normalized fraction is
+.I x
+times a power of two,
+and its absolute value is always in the range 1/2 (inclusive) to
+1 (exclusive), that is, [0.5,1).
+.P
+If
+.I x
+is zero, then the normalized fraction is
+zero and zero is stored in
+.IR exp .
+.P
+If
+.I x
+is a NaN,
+a NaN is returned, and the value of
+.I *exp
+is unspecified.
+.P
+If
+.I x
+is positive infinity (negative infinity),
+positive infinity (negative infinity) is returned, and the value of
+.I *exp
+is unspecified.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR frexp (),
+.BR frexpf (),
+.BR frexpl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH EXAMPLES
+The program below produces results such as the following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 2560"
+frexp(2560, &e) = 0.625: 0.625 * 2\[ha]12 = 2560
+.RB "$" " ./a.out \-4"
+frexp(\-4, &e) = \-0.5: \-0.5 * 2\[ha]3 = \-4
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (frexp.c)
+.EX
+#include <float.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    double x, r;
+    int exp;
+\&
+    x = strtod(argv[1], NULL);
+    r = frexp(x, &exp);
+\&
+    printf("frexp(%g, &e) = %g: %g * %d\[ha]%d = %g\en", x, r, r, 2, exp, x);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR ldexp (3),
+.BR modf (3)
diff --git a/man/man3/frexpf.3 b/man/man3/frexpf.3
new file mode 100644
index 000000000..980426f3d
--- /dev/null
+++ b/man/man3/frexpf.3
@@ -0,0 +1 @@
+.so man3/frexp.3
diff --git a/man/man3/frexpl.3 b/man/man3/frexpl.3
new file mode 100644
index 000000000..980426f3d
--- /dev/null
+++ b/man/man3/frexpl.3
@@ -0,0 +1 @@
+.so man3/frexp.3
diff --git a/man/man3/fscanf.3 b/man/man3/fscanf.3
new file mode 100644
index 000000000..9fd424bb2
--- /dev/null
+++ b/man/man3/fscanf.3
@@ -0,0 +1 @@
+.so man3/scanf.3
diff --git a/man/man3/fseek.3 b/man/man3/fseek.3
new file mode 100644
index 000000000..64a23bbee
--- /dev/null
+++ b/man/man3/fseek.3
@@ -0,0 +1,177 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)fseek.3	6.11 (Berkeley) 6/29/91
+.\"
+.\" Converted for Linux, Mon Nov 29 15:22:01 1993, faith@cs.unc.edu
+.\"
+.TH fseek 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fgetpos, fseek, fsetpos, ftell, rewind \- reposition a stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int fseek(FILE *" stream ", long " offset ", int " whence );
+.BI "long ftell(FILE *" stream );
+.P
+.BI "void rewind(FILE *" stream );
+.P
+.BI "int fgetpos(FILE *restrict " stream ", fpos_t *restrict " pos );
+.BI "int fsetpos(FILE *" stream ", const fpos_t *" pos );
+.fi
+.SH DESCRIPTION
+The
+.BR fseek ()
+function sets the file position indicator for the stream pointed to by
+.IR stream .
+The new position, measured in bytes, is obtained by adding
+.I offset
+bytes to the position specified by
+.IR whence .
+If
+.I whence
+is set to
+.BR SEEK_SET ,
+.BR SEEK_CUR ,
+or
+.BR SEEK_END ,
+the offset is relative to the start of the file, the current position
+indicator, or end-of-file, respectively.
+A successful call to the
+.BR fseek ()
+function clears the end-of-file indicator for the stream and undoes
+any effects of the
+.BR ungetc (3)
+function on the same stream.
+.P
+The
+.BR ftell ()
+function obtains the current value of the file position indicator for the
+stream pointed to by
+.IR stream .
+.P
+The
+.BR rewind ()
+function sets the file position indicator for the stream pointed to by
+.I stream
+to the beginning of the file.
+It is equivalent to:
+.P
+.RS
+(void) fseek(stream, 0L, SEEK_SET)
+.RE
+.P
+except that the error indicator for the stream is also cleared (see
+.BR clearerr (3)).
+.P
+The
+.BR fgetpos ()
+and
+.BR fsetpos ()
+functions are alternate interfaces equivalent to
+.BR ftell ()
+and
+.BR fseek ()
+(with
+.I whence
+set to
+.BR SEEK_SET ),
+setting and storing the current value of the file offset into or from the
+object referenced by
+.IR pos .
+On some non-UNIX systems, an
+.I fpos_t
+object may be a complex object and these routines may be the only way to
+portably reposition a text stream.
+.P
+If the stream refers to a regular file
+and the resulting stream offset is beyond the size of the file,
+subsequent writes will extend the file with a hole, up to the offset,
+before committing any data.
+See
+.BR lseek (2)
+for details on file seeking semantics.
+.SH RETURN VALUE
+The
+.BR rewind ()
+function returns no value.
+Upon successful completion,
+.BR fgetpos (),
+.BR fseek (),
+.BR fsetpos ()
+return 0,
+and
+.BR ftell ()
+returns the current offset.
+Otherwise, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The
+.I whence
+argument to
+.BR fseek ()
+was not
+.BR SEEK_SET ,
+.BR SEEK_END ,
+or
+.BR SEEK_CUR .
+Or: the resulting file offset would be negative.
+.TP
+.B ESPIPE
+The file descriptor underlying
+.I stream
+is not seekable (e.g., it refers to a pipe, FIFO, or socket).
+.P
+The functions
+.BR fgetpos (),
+.BR fseek (),
+.BR fsetpos (),
+and
+.BR ftell ()
+may also fail and set
+.I errno
+for any of the errors specified for the routines
+.BR fflush (3),
+.BR fstat (2),
+.BR lseek (2),
+and
+.BR malloc (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fseek (),
+.BR ftell (),
+.BR rewind (),
+.BR fgetpos (),
+.BR fsetpos ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89.
+.SH SEE ALSO
+.BR lseek (2),
+.BR fseeko (3)
diff --git a/man/man3/fseeko.3 b/man/man3/fseeko.3
new file mode 100644
index 000000000..2f698ac0e
--- /dev/null
+++ b/man/man3/fseeko.3
@@ -0,0 +1,102 @@
+'\" t
+.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH fseeko 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fseeko, ftello \- seek to or report file position
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int fseeko(FILE *" stream ", off_t " offset ", int " whence );
+.BI "off_t ftello(FILE *" stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fseeko (),
+.BR ftello ():
+.nf
+    _FILE_OFFSET_BITS == 64 || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR fseeko ()
+and
+.BR ftello ()
+functions are identical to
+.BR fseek (3)
+and
+.BR ftell (3)
+(see
+.BR fseek (3)),
+respectively, except that the
+.I offset
+argument of
+.BR fseeko ()
+and the return value of
+.BR ftello ()
+is of type
+.I off_t
+instead of
+.IR long .
+.P
+On some architectures, both
+.I off_t
+and
+.I long
+are 32-bit types, but defining
+.B _FILE_OFFSET_BITS
+with the value 64 (before including
+.I any
+header files)
+will turn
+.I off_t
+into a 64-bit type.
+.SH RETURN VALUE
+On successful completion,
+.BR fseeko ()
+returns 0, while
+.BR ftello ()
+returns the current offset.
+Otherwise, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+See the ERRORS in
+.BR fseek (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fseeko (),
+.BR ftello ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001, SUSv2.
+.SH NOTES
+The declarations of these functions can also be obtained by defining
+the obsolete
+.B _LARGEFILE_SOURCE
+feature test macro.
+.SH SEE ALSO
+.BR fseek (3)
diff --git a/man/man3/fsetpos.3 b/man/man3/fsetpos.3
new file mode 100644
index 000000000..a1487b5a8
--- /dev/null
+++ b/man/man3/fsetpos.3
@@ -0,0 +1 @@
+.so man3/fseek.3
diff --git a/man/man3/fstatvfs.3 b/man/man3/fstatvfs.3
new file mode 100644
index 000000000..adec9ddea
--- /dev/null
+++ b/man/man3/fstatvfs.3
@@ -0,0 +1 @@
+.so man3/statvfs.3
diff --git a/man/man3/ftell.3 b/man/man3/ftell.3
new file mode 100644
index 000000000..a1487b5a8
--- /dev/null
+++ b/man/man3/ftell.3
@@ -0,0 +1 @@
+.so man3/fseek.3
diff --git a/man/man3/ftello.3 b/man/man3/ftello.3
new file mode 100644
index 000000000..d5628f46d
--- /dev/null
+++ b/man/man3/ftello.3
@@ -0,0 +1 @@
+.so man3/fseeko.3
diff --git a/man/man3/ftime.3 b/man/man3/ftime.3
new file mode 100644
index 000000000..28fb6bffe
--- /dev/null
+++ b/man/man3/ftime.3
@@ -0,0 +1,105 @@
+'\" t
+.\" Copyright (c) 1993 Michael Haardt
+.\" (michael@moria.de)
+.\" Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 14:23:14 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Oct 18 17:31:43 1998 by Andries Brouwer (aeb@cwi.nl)
+.\" 2008-06-23, mtk, minor rewrites, added some details
+.\"
+.TH ftime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ftime \- return date and time
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <sys/timeb.h>"
+.P
+.BI "int ftime(struct timeb *" tp );
+.fi
+.SH DESCRIPTION
+.BR NOTE :
+This function is no longer provided by the GNU C library.
+Use
+.BR clock_gettime (2)
+instead.
+.P
+This function returns the current time as seconds and milliseconds
+since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+The time is returned in
+.IR tp ,
+which is declared as follows:
+.P
+.in +4n
+.EX
+struct timeb {
+    time_t         time;
+    unsigned short millitm;
+    short          timezone;
+    short          dstflag;
+};
+.EE
+.in
+.P
+Here \fItime\fP is the number of seconds since the Epoch,
+and \fImillitm\fP is the number of milliseconds since \fItime\fP
+seconds since the Epoch.
+The \fItimezone\fP field is the local timezone measured in minutes
+of time west of Greenwich (with a negative value indicating minutes
+east of Greenwich).
+The \fIdstflag\fP field
+is a flag that, if nonzero, indicates that Daylight Saving time
+applies locally during the appropriate part of the year.
+.P
+POSIX.1-2001 says that the contents of the \fItimezone\fP and \fIdstflag\fP
+fields are unspecified; avoid relying on them.
+.SH RETURN VALUE
+This function always returns 0.
+(POSIX.1-2001 specifies, and some systems document, a \-1 error return.)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ftime ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+Removed in glibc 2.33.
+4.2BSD, POSIX.1-2001.
+Removed in POSIX.1-2008.
+.P
+This function is obsolete.
+Don't use it.
+If the time in seconds
+suffices,
+.BR time (2)
+can be used;
+.BR gettimeofday (2)
+gives microseconds;
+.BR clock_gettime (2)
+gives nanoseconds but is not as widely available.
+.SH BUGS
+Early glibc2 is buggy and returns 0 in the
+.I millitm
+field;
+glibc 2.1.1 is correct again.
+.\" .SH HISTORY
+.\" The
+.\" .BR ftime ()
+.\" function appeared in 4.2BSD.
+.SH SEE ALSO
+.BR gettimeofday (2),
+.BR time (2)
diff --git a/man/man3/ftok.3 b/man/man3/ftok.3
new file mode 100644
index 000000000..74fad12b2
--- /dev/null
+++ b/man/man3/ftok.3
@@ -0,0 +1,110 @@
+'\" t
+.\" Copyright 1993 Giorgio Ciucci (giorgio@crcc.it)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 2001-11-28, by Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"	Changed data type of proj_id; minor fixes
+.\"	aeb: further fixes; added notes.
+.\"
+.TH ftok 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ftok \- convert a pathname and a project identifier to a System V IPC key
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/ipc.h>
+.fi
+.P
+.BI "key_t ftok(const char *" pathname ", int " proj_id );
+.SH DESCRIPTION
+The
+.BR ftok ()
+function uses the identity of the file named by the given
+.I pathname
+(which must refer to an existing, accessible file)
+and the least significant 8 bits of
+.I proj_id
+(which must be nonzero) to generate a
+.I key_t
+type System V IPC key, suitable for use with
+.BR msgget (2),
+.BR semget (2),
+or
+.BR shmget (2).
+.P
+The resulting value is the same for all pathnames that
+name the same file, when the same value of
+.I proj_id
+is used.
+The value returned should be different when the
+(simultaneously existing) files or the project IDs differ.
+.SH RETURN VALUE
+On success, the generated
+.I key_t
+value is returned.
+On failure \-1 is returned, with
+.I errno
+indicating the error as for the
+.BR stat (2)
+system call.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ftok ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+On some ancient systems, the prototype was:
+.P
+.in +4n
+.EX
+.BI "key_t ftok(char *" pathname ", char " proj_id );
+.EE
+.in
+.P
+Today,
+.I proj_id
+is an
+.IR int ,
+but still only 8 bits are used.
+Typical usage has an ASCII character
+.IR proj_id ,
+that is why the behavior is said to be undefined when
+.I proj_id
+is zero.
+.P
+Of course, no guarantee can be given that the resulting
+.I key_t
+is unique.
+Typically, a best-effort attempt combines the given
+.I proj_id
+byte, the lower 16 bits of the inode number, and the
+lower 8 bits of the device number into a 32-bit result.
+Collisions may easily happen, for example between files on
+.I /dev/hda1
+and files on
+.IR /dev/sda1 .
+.SH EXAMPLES
+See
+.BR semget (2).
+.SH SEE ALSO
+.BR msgget (2),
+.BR semget (2),
+.BR shmget (2),
+.BR stat (2),
+.BR sysvipc (7)
diff --git a/man/man3/ftrylockfile.3 b/man/man3/ftrylockfile.3
new file mode 100644
index 000000000..b33c2ee65
--- /dev/null
+++ b/man/man3/ftrylockfile.3
@@ -0,0 +1 @@
+.so man3/flockfile.3
diff --git a/man/man3/fts.3 b/man/man3/fts.3
new file mode 100644
index 000000000..d2c520450
--- /dev/null
+++ b/man/man3/fts.3
@@ -0,0 +1,826 @@
+'\" t
+.\"	$NetBSD: fts.3,v 1.13.2.1 1997/11/14 02:09:32 mrg Exp $
+.\"
+.\" Copyright (c) 1989, 1991, 1993, 1994
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)fts.3	8.5 (Berkeley) 4/16/94
+.\"
+.\" 2007-12-08, mtk, Converted from mdoc to man macros
+.\"
+.TH fts 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fts, fts_open, fts_read, fts_children, fts_set, fts_close \- \
+traverse a file hierarchy
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <sys/stat.h>
+.B #include <fts.h>
+.P
+.BI "FTS *fts_open(char *const *" path_argv ", int " options ,
+.BI "              int (*_Nullable " compar ")(const FTSENT **, const FTSENT **));"
+.P
+.BI "FTSENT *fts_read(FTS *" ftsp );
+.P
+.BI "FTSENT *fts_children(FTS *" ftsp ", int " instr );
+.P
+.BI "int fts_set(FTS *" ftsp ", FTSENT *" f ", int " instr );
+.P
+.BI "int fts_close(FTS *" ftsp );
+.fi
+.SH DESCRIPTION
+The
+fts functions are provided for traversing
+file hierarchies.
+A simple overview is that the
+.BR fts_open ()
+function returns a "handle" (of type
+.IR "FTS\ *" )
+that refers to a file hierarchy "stream".
+This handle is then supplied to the other
+fts functions.
+The function
+.BR fts_read ()
+returns a pointer to a structure describing one of the files in the file
+hierarchy.
+The function
+.BR fts_children ()
+returns a pointer to a linked list of structures, each of which describes
+one of the files contained in a directory in the hierarchy.
+.P
+In general, directories are visited two distinguishable times; in preorder
+(before any of their descendants are visited) and in postorder (after all
+of their descendants have been visited).
+Files are visited once.
+It is possible to walk the hierarchy "logically" (visiting the files that
+symbolic links point to)
+or physically (visiting the symbolic links themselves),
+order the walk of the hierarchy or
+prune and/or revisit portions of the hierarchy.
+.P
+Two structures (and associated types) are defined in the include file
+.IR <fts.h> .
+The first type is
+.IR FTS ,
+the structure that represents the file hierarchy itself.
+The second type is
+.IR FTSENT ,
+the structure that represents a file in the file
+hierarchy.
+Normally, an
+.I FTSENT
+structure is returned for every file in the file
+hierarchy.
+In this manual page, "file" and
+"FTSENT structure"
+are generally interchangeable.
+.P
+The
+.I FTSENT
+structure contains fields describing a file.
+The structure contains at least the following fields
+(there are additional fields that
+should be considered private to the implementation):
+.P
+.in +4n
+.EX
+typedef struct _ftsent {
+    unsigned short  fts_info;     /* flags for FTSENT structure */
+    char           *fts_accpath;  /* access path */
+    char           *fts_path;     /* root path */
+    short           fts_pathlen;  /* strlen(fts_path) +
+                                     strlen(fts_name) */
+    char           *fts_name;     /* filename */
+    short           fts_namelen;  /* strlen(fts_name) */
+    short           fts_level;    /* depth (\-1 to N) */
+    int             fts_errno;    /* file errno */
+    long            fts_number;   /* local numeric value */
+    void           *fts_pointer;  /* local address value */
+    struct _ftsent *fts_parent;   /* parent directory */
+    struct _ftsent *fts_link;     /* next file structure */
+    struct _ftsent *fts_cycle;    /* cycle structure */
+    struct stat    *fts_statp;    /* [l]stat(2) information */
+.\" Also:
+.\"     ino_t fts_ino;                  /* inode (only for directories)*/
+.\"     dev_t fts_dev;                  /* device (only for directories)*/
+.\"     nlink_t fts_nlink;              /* link count (only for directories)*/
+.\"     u_short fts_flags;              /* private flags for FTSENT structure */
+.\"     u_short fts_instr;              /* fts_set() instructions */
+} FTSENT;
+.EE
+.in
+.P
+These fields are defined as follows:
+.\" .Bl -tag -width "fts_namelen"
+.TP
+.I fts_info
+One of the following values describing the returned
+.I FTSENT
+structure and
+the file it represents.
+With the exception of directories without errors
+.RB ( FTS_D ),
+all of these
+entries are terminal, that is, they will not be revisited, nor will any
+of their descendants be visited.
+.\" .Bl  -tag -width FTS_DEFAULT
+.RS
+.TP
+.B FTS_D
+A directory being visited in preorder.
+.TP
+.B FTS_DC
+A directory that causes a cycle in the tree.
+(The
+.I fts_cycle
+field of the
+.I FTSENT
+structure will be filled in as well.)
+.TP
+.B FTS_DEFAULT
+Any
+.I FTSENT
+structure that represents a file type not explicitly described
+by one of the other
+.I fts_info
+values.
+.TP
+.B FTS_DNR
+A directory which cannot be read.
+This is an error return, and the
+.I fts_errno
+field will be set to indicate what caused the error.
+.TP
+.B FTS_DOT
+A file named
+"."
+or
+".."
+which was not specified as a filename to
+.BR fts_open ()
+(see
+.BR FTS_SEEDOT ).
+.TP
+.B FTS_DP
+A directory being visited in postorder.
+The contents of the
+.I FTSENT
+structure will be unchanged from when
+it was returned in preorder, that is, with the
+.I fts_info
+field set to
+.BR FTS_D .
+.TP
+.B FTS_ERR
+This is an error return, and the
+.I fts_errno
+field will be set to indicate what caused the error.
+.TP
+.B FTS_F
+A regular file.
+.TP
+.B FTS_NS
+A file for which no
+.RB [ l ]\c
+.BR stat (2)
+information was available.
+The contents of the
+.I fts_statp
+field are undefined.
+This is an error return, and the
+.I fts_errno
+field will be set to indicate what caused the error.
+.TP
+.B FTS_NSOK
+A file for which no
+.RB [ l ]\c
+.BR stat (2)
+information was requested.
+The contents of the
+.I fts_statp
+field are undefined.
+.TP
+.B FTS_SL
+A symbolic link.
+.TP
+.B FTS_SLNONE
+A symbolic link with a nonexistent target.
+The contents of the
+.I fts_statp
+field reference the file characteristic information for the symbolic link
+itself.
+.\" .El
+.RE
+.TP
+.I fts_accpath
+A path for accessing the file from the current directory.
+.TP
+.I fts_path
+The path for the file relative to the root of the traversal.
+This path contains the path specified to
+.BR fts_open ()
+as a prefix.
+.TP
+.I fts_pathlen
+The sum of the lengths of the strings referenced by
+.I fts_path
+and
+.IR fts_name .
+.TP
+.I fts_name
+The name of the file.
+.TP
+.I fts_namelen
+The length of the string referenced by
+.IR fts_name .
+.TP
+.I fts_level
+The depth of the traversal, numbered from \-1 to N, where this file
+was found.
+The
+.I FTSENT
+structure representing the parent of the starting point (or root)
+of the traversal is numbered \-1, and the
+.I FTSENT
+structure for the root
+itself is numbered 0.
+.TP
+.I fts_errno
+If
+.BR fts_children ()
+or
+.BR fts_read ()
+returns an
+.I FTSENT
+structure whose
+.I fts_info
+field is set to
+.BR FTS_DNR ,
+.BR FTS_ERR ,
+or
+.BR FTS_NS ,
+the
+.I fts_errno
+field contains the error number (i.e., the
+.I errno
+value)
+specifying the cause of the error.
+Otherwise, the contents of the
+.I fts_errno
+field are undefined.
+.TP
+.I fts_number
+This field is provided for the use of the application program and is
+not modified by the
+fts functions.
+It is initialized to 0.
+.TP
+.I fts_pointer
+This field is provided for the use of the application program and is
+not modified by the
+fts functions.
+It is initialized to
+NULL.
+.TP
+.I fts_parent
+A pointer to the
+.I FTSENT
+structure referencing the file in the hierarchy
+immediately above the current file, that is, the directory of which this
+file is a member.
+A parent structure for the initial entry point is provided as well,
+however, only the
+.IR fts_level ,
+.IR fts_number ,
+and
+.I fts_pointer
+fields are guaranteed to be initialized.
+.TP
+.I fts_link
+Upon return from the
+.BR fts_children ()
+function, the
+.I fts_link
+field points to the next structure in the NULL-terminated linked list of
+directory members.
+Otherwise, the contents of the
+.I fts_link
+field are undefined.
+.TP
+.I fts_cycle
+If a directory causes a cycle in the hierarchy (see
+.BR FTS_DC ),
+either because
+of a hard link between two directories, or a symbolic link pointing to a
+directory, the
+.I fts_cycle
+field of the structure will point to the
+.I FTSENT
+structure in the hierarchy that references the same file as the current
+.I FTSENT
+structure.
+Otherwise, the contents of the
+.I fts_cycle
+field are undefined.
+.TP
+.I fts_statp
+A pointer to
+.RB [ l ]\c
+.BR stat (2)
+information for the file.
+.\" .El
+.P
+A single buffer is used for all of the paths of all of the files in the
+file hierarchy.
+Therefore, the
+.I fts_path
+and
+.I fts_accpath
+fields are guaranteed to be
+null-terminated
+.I only
+for the file most recently returned by
+.BR fts_read ().
+To use these fields to reference any files represented by other
+.I FTSENT
+structures will require that the path buffer be modified using the
+information contained in that
+.I FTSENT
+structure's
+.I fts_pathlen
+field.
+Any such modifications should be undone before further calls to
+.BR fts_read ()
+are attempted.
+The
+.I fts_name
+field is always
+null-terminated.
+.SS fts_open()
+The
+.BR fts_open ()
+function takes a pointer to an array of character pointers naming one
+or more paths which make up a logical file hierarchy to be traversed.
+The array must be terminated by a
+null pointer.
+.P
+There are
+a number of options, at least one of which (either
+.B FTS_LOGICAL
+or
+.BR FTS_PHYSICAL )
+must be specified.
+The options are selected by ORing
+the following values:
+.\" .Bl -tag -width "FTS_PHYSICAL"
+.TP
+.B FTS_LOGICAL
+This option causes the
+fts routines to return
+.I FTSENT
+structures for the targets of symbolic links
+instead of the symbolic links themselves.
+If this option is set, the only symbolic links for which
+.I FTSENT
+structures
+are returned to the application are those referencing nonexistent files:
+the
+.I fts_statp
+field is obtained via
+.BR stat (2)
+with a fallback to
+.BR lstat (2).
+.TP
+.B FTS_PHYSICAL
+This option causes the
+fts routines to return
+.I FTSENT
+structures for symbolic links themselves instead
+of the target files they point to.
+If this option is set,
+.I FTSENT
+structures for all symbolic links in the
+hierarchy are returned to the application:
+the
+.I fts_statp
+field is obtained via
+.BR lstat (2).
+.TP
+.B FTS_COMFOLLOW
+This option causes any symbolic link specified as a root path to be
+followed immediately, as if via
+.BR FTS_LOGICAL ,
+regardless of the primary mode.
+.TP
+.B FTS_NOCHDIR
+As a performance optimization, the
+fts functions change directories as they walk the file hierarchy.
+This has the side-effect that an application cannot rely on being
+in any particular directory during the traversal.
+This
+option turns off this optimization, and the
+fts functions will not change the current directory.
+Note that applications should not themselves change their current directory
+and try to access files unless
+.B FTS_NOCHDIR
+is specified and absolute
+pathnames were provided as arguments to
+.BR fts_open ().
+.TP
+.B FTS_NOSTAT
+By default, returned
+.I FTSENT
+structures reference file characteristic information (the
+.I fts_statp
+field) for each file visited.
+This option relaxes that requirement as a performance optimization,
+allowing the
+fts functions to set the
+.I fts_info
+field to
+.B FTS_NSOK
+and leave the contents of the
+.I fts_statp
+field undefined.
+.TP
+.B FTS_SEEDOT
+By default, unless they are specified as path arguments to
+.BR fts_open (),
+any files named
+"."
+or
+".."
+encountered in the file hierarchy are ignored.
+This option causes the
+fts routines to return
+.I FTSENT
+structures for them.
+.TP
+.B FTS_XDEV
+This option prevents
+fts from descending into directories that have a different device number
+than the file from which the descent began.
+.\" .El
+.P
+The argument
+.BR compar ()
+specifies a user-defined function which may be used to order the traversal
+of the hierarchy.
+It
+takes two pointers to pointers to
+.I FTSENT
+structures as arguments and
+should return a negative value, zero, or a positive value to indicate
+if the file referenced by its first argument comes before, in any order
+with respect to, or after, the file referenced by its second argument.
+The
+.IR fts_accpath ,
+.IR fts_path ,
+and
+.I fts_pathlen
+fields of the
+.I FTSENT
+structures may
+.I never
+be used in this comparison.
+If the
+.I fts_info
+field is set to
+.B FTS_NS
+or
+.BR FTS_NSOK ,
+the
+.I fts_statp
+field may not either.
+If the
+.BR compar ()
+argument is
+NULL,
+the directory traversal order is in the order listed in
+.I path_argv
+for the root paths, and in the order listed in the directory for
+everything else.
+.SS fts_read()
+The
+.BR fts_read ()
+function returns a pointer to an
+.I FTSENT
+structure describing a file in
+the hierarchy.
+Directories (that are readable and do not cause cycles) are visited at
+least twice, once in preorder and once in postorder.
+All other files are visited at least once.
+(Hard links between directories that do not cause cycles or symbolic
+links to symbolic links may cause files to be visited more than once,
+or directories more than twice.)
+.P
+If all the members of the hierarchy have been returned,
+.BR fts_read ()
+returns NULL and sets
+.I errno
+to 0.
+If an error unrelated to a file in the hierarchy occurs,
+.BR fts_read ()
+returns
+NULL
+and sets
+.I errno
+to indicate the error.
+If an error related to a returned file occurs, a pointer to an
+.I FTSENT
+structure is returned, and
+.I errno
+may or may not have been set (see
+.IR fts_info ).
+.P
+The
+.I FTSENT
+structures returned by
+.BR fts_read ()
+may be overwritten after a call to
+.BR fts_close ()
+on the same file hierarchy stream, or, after a call to
+.BR fts_read ()
+on the same file hierarchy stream unless they represent a file of type
+directory, in which case they will not be overwritten until after a call to
+.BR fts_read ()
+after the
+.I FTSENT
+structure has been returned by the function
+.BR fts_read ()
+in postorder.
+.SS fts_children()
+The
+.BR fts_children ()
+function returns a pointer to an
+.I FTSENT
+structure describing the first entry in a NULL-terminated linked list of
+the files in the directory represented by the
+.I FTSENT
+structure most recently returned by
+.BR fts_read ().
+The list is linked through the
+.I fts_link
+field of the
+.I FTSENT
+structure, and is ordered by the user-specified comparison function, if any.
+Repeated calls to
+.BR fts_children ()
+will re-create this linked list.
+.P
+As a special case, if
+.BR fts_read ()
+has not yet been called for a hierarchy,
+.BR fts_children ()
+will return a pointer to the files in the logical directory specified to
+.BR fts_open (),
+that is, the arguments specified to
+.BR fts_open ().
+Otherwise, if the
+.I FTSENT
+structure most recently returned by
+.BR fts_read ()
+is not a directory being visited in preorder,
+or the directory does not contain any files,
+.BR fts_children ()
+returns
+NULL
+and sets
+.I errno
+to zero.
+If an error occurs,
+.BR fts_children ()
+returns
+NULL
+and sets
+.I errno
+to indicate the error.
+.P
+The
+.I FTSENT
+structures returned by
+.BR fts_children ()
+may be overwritten after a call to
+.BR fts_children (),
+.BR fts_close (),
+or
+.BR fts_read ()
+on the same file hierarchy stream.
+.P
+The
+.I instr
+argument is either zero or the following value:
+.\" .Bl -tag -width FTS_NAMEONLY
+.TP
+.B FTS_NAMEONLY
+Only the names of the files are needed.
+The contents of all the fields in the returned linked list of structures
+are undefined with the exception of the
+.I fts_name
+and
+.I fts_namelen
+fields.
+.\" .El
+.SS fts_set()
+The function
+.BR fts_set ()
+allows the user application to determine further processing for the
+file
+.I f
+of the stream
+.IR ftsp .
+The
+.BR fts_set ()
+function
+returns 0 on success, and \-1 if an error occurs.
+.P
+The
+.I instr
+argument is either 0 (meaning "do nothing") or one of the following values:
+.\" .Bl -tag -width FTS_PHYSICAL
+.TP
+.B FTS_AGAIN
+Revisit the file; any file type may be revisited.
+The next call to
+.BR fts_read ()
+will return the referenced file.
+The
+.I fts_stat
+and
+.I fts_info
+fields of the structure will be reinitialized at that time,
+but no other fields will have been changed.
+This option is meaningful only for the most recently returned
+file from
+.BR fts_read ().
+Normal use is for postorder directory visits, where it causes the
+directory to be revisited (in both preorder and postorder) as well as all
+of its descendants.
+.TP
+.B FTS_FOLLOW
+The referenced file must be a symbolic link.
+If the referenced file is the one most recently returned by
+.BR fts_read (),
+the next call to
+.BR fts_read ()
+returns the file with the
+.I fts_info
+and
+.I fts_statp
+fields reinitialized to reflect the target of the symbolic link instead
+of the symbolic link itself.
+If the file is one of those most recently returned by
+.BR fts_children (),
+the
+.I fts_info
+and
+.I fts_statp
+fields of the structure, when returned by
+.BR fts_read (),
+will reflect the target of the symbolic link instead of the symbolic link
+itself.
+In either case, if the target of the symbolic link does not exist, the
+fields of the returned structure will be unchanged and the
+.I fts_info
+field will be set to
+.BR FTS_SLNONE .
+.IP
+If the target of the link is a directory, the preorder return, followed
+by the return of all of its descendants, followed by a postorder return,
+is done.
+.TP
+.B FTS_SKIP
+No descendants of this file are visited.
+The file may be one of those most recently returned by either
+.BR fts_children ()
+or
+.BR fts_read ().
+.\" .El
+.SS fts_close()
+The
+.BR fts_close ()
+function closes the file hierarchy stream referred to by
+.I ftsp
+and restores the current directory to the directory from which
+.BR fts_open ()
+was called to open
+.IR ftsp .
+The
+.BR fts_close ()
+function
+returns 0 on success, and \-1 if an error occurs.
+.SH ERRORS
+The function
+.BR fts_open ()
+may fail and set
+.I errno
+for any of the errors specified for
+.BR open (2)
+and
+.BR malloc (3).
+.P
+In addition,
+.BR fts_open ()
+may fail and set
+.I errno
+as follows:
+.TP
+.B ENOENT
+Any element of
+.I path_argv
+was an empty string.
+.P
+The function
+.BR fts_close ()
+may fail and set
+.I errno
+for any of the errors specified for
+.BR chdir (2)
+and
+.BR close (2).
+.P
+The functions
+.BR fts_read ()
+and
+.BR fts_children ()
+may fail and set
+.I errno
+for any of the errors specified for
+.BR chdir (2),
+.BR malloc (3),
+.BR opendir (3),
+.BR readdir (3),
+and
+.RB [ l ]\c
+.BR stat (2).
+.P
+In addition,
+.BR fts_children (),
+.BR fts_open (),
+and
+.BR fts_set ()
+may fail and set
+.I errno
+as follows:
+.TP
+.B EINVAL
+.I options
+or
+.I instr
+was invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fts_open (),
+.BR fts_set (),
+.BR fts_close ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR fts_read (),
+.BR fts_children ()
+T}	Thread safety	MT-Unsafe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.
+4.4BSD.
+.SH BUGS
+Before glibc 2.23,
+.\" Fixed by commit 8b7b7f75d91f7bac323dd6a370aeb3e9c5c4a7d5
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=15838
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=11460
+all of the APIs described in this man page are not safe when compiling
+a program using the LFS APIs (e.g., when compiling with
+.IR \-D_FILE_OFFSET_BITS=64 ).
+.\"
+.\" The following statement is years old, and seems no closer to
+.\" being true -- mtk
+.\" The
+.\" .I fts
+.\" utility is expected to be included in a future
+.\" POSIX.1
+.\" revision.
+.SH SEE ALSO
+.BR find (1),
+.BR chdir (2),
+.BR lstat (2),
+.BR stat (2),
+.BR ftw (3),
+.BR qsort (3)
diff --git a/man/man3/fts_children.3 b/man/man3/fts_children.3
new file mode 100644
index 000000000..85caf7524
--- /dev/null
+++ b/man/man3/fts_children.3
@@ -0,0 +1 @@
+.so man3/fts.3
diff --git a/man/man3/fts_close.3 b/man/man3/fts_close.3
new file mode 100644
index 000000000..85caf7524
--- /dev/null
+++ b/man/man3/fts_close.3
@@ -0,0 +1 @@
+.so man3/fts.3
diff --git a/man/man3/fts_open.3 b/man/man3/fts_open.3
new file mode 100644
index 000000000..85caf7524
--- /dev/null
+++ b/man/man3/fts_open.3
@@ -0,0 +1 @@
+.so man3/fts.3
diff --git a/man/man3/fts_read.3 b/man/man3/fts_read.3
new file mode 100644
index 000000000..85caf7524
--- /dev/null
+++ b/man/man3/fts_read.3
@@ -0,0 +1 @@
+.so man3/fts.3
diff --git a/man/man3/fts_set.3 b/man/man3/fts_set.3
new file mode 100644
index 000000000..85caf7524
--- /dev/null
+++ b/man/man3/fts_set.3
@@ -0,0 +1 @@
+.so man3/fts.3
diff --git a/man/man3/ftw.3 b/man/man3/ftw.3
new file mode 100644
index 000000000..655bd38ac
--- /dev/null
+++ b/man/man3/ftw.3
@@ -0,0 +1,502 @@
+'\" t
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de)
+.\" and copyright (c) 1999 Andries Brouwer (aeb@cwi.nl)
+.\" and copyright (c) 2006 Justin Pryzby <justinpryzby@users.sf.net>
+.\" and copyright (c) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sun Jul 25 11:02:22 1993 by Rik Faith (faith@cs.unc.edu)
+.\" 2006-05-24, Justin Pryzby <justinpryzby@users.sf.net>
+.\"  	document FTW_ACTIONRETVAL; include .SH RETURN VALUE;
+.\" 2006-05-24, Justin Pryzby <justinpryzby@users.sf.net> and
+.\"	Michael Kerrisk <mtk.manpages@gmail.com>
+.\" 	reorganized and rewrote much of the page
+.\" 2006-05-24, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added an example program.
+.\"
+.TH ftw 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ftw, nftw \- file tree walk
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <ftw.h>
+.P
+.BI "int nftw(const char *" dirpath ,
+.BI "        int (*" fn ")(const char *" fpath ", const struct stat *" sb ,
+.BI "                  int " typeflag ", struct FTW *" ftwbuf ),
+.BI "        int " nopenfd ", int " flags );
+.P
+.B [[deprecated]]
+.BI "int ftw(const char *" dirpath ,
+.BI "        int (*" fn ")(const char *" fpath ", const struct stat *" sb ,
+.BI "                  int " typeflag ),
+.BI "        int " nopenfd );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR nftw ():
+.nf
+    _XOPEN_SOURCE >= 500
+.fi
+.SH DESCRIPTION
+.BR nftw ()
+walks through the directory tree that is
+located under the directory \fIdirpath\fP,
+and calls \fIfn\fP() once for each entry in the tree.
+By default, directories are handled before the files and
+subdirectories they contain (preorder traversal).
+.P
+To avoid using up all of the calling process's file descriptors,
+\fInopenfd\fP specifies the maximum number of directories that
+.BR nftw ()
+will hold open simultaneously.
+When
+the search depth exceeds this,
+.BR nftw ()
+will become slower because
+directories have to be closed and reopened.
+.BR nftw ()
+uses at most
+one file descriptor for each level in the directory tree.
+.P
+For each entry found in the tree,
+.BR nftw ()
+calls
+\fIfn\fP() with four arguments:
+.IR fpath ,
+.IR sb ,
+.IR typeflag ,
+and
+.IR ftwbuf .
+.I fpath
+is the pathname of the entry,
+and is expressed either as a pathname relative to the calling process's
+current working directory at the time of the call to
+.BR nftw (),
+if
+.I dirpath
+was expressed as a relative pathname,
+or as an absolute pathname, if
+.I dirpath
+was expressed as an absolute pathname.
+.I sb
+is a pointer to the
+.I stat
+structure returned by a call to
+.BR stat (2)
+for
+.IR fpath .
+.P
+The
+.I typeflag
+argument passed to
+.IR fn ()
+is an integer that has one of the following values:
+.TP
+.B FTW_F
+.I fpath
+is a regular file.
+.TP
+.B FTW_D
+.I fpath
+is a directory.
+.TP
+.B FTW_DNR
+.I fpath
+is a directory which can't be read.
+.TP
+.B FTW_DP
+.I fpath
+is a directory, and \fBFTW_DEPTH\fP was specified in \fIflags\fP.
+(If
+.B FTW_DEPTH
+was not specified in
+.IR flags ,
+then directories will always be visited with
+.I typeflag
+set to
+.BR FTW_D .)
+All of the files
+and subdirectories within \fIfpath\fP have been processed.
+.TP
+.B FTW_NS
+The
+.BR stat (2)
+call failed on
+.IR fpath ,
+which is not a symbolic link.
+The probable cause for this is that the caller had read permission
+on the parent directory, so that the filename
+.I fpath
+could be seen,
+but did not have execute permission,
+so that the file could not be reached for
+.BR stat (2).
+The contents of the buffer pointed to by
+.I sb
+are undefined.
+.TP
+.B FTW_SL
+.I fpath
+is a symbolic link, and \fBFTW_PHYS\fP was set in \fIflags\fP.
+.\" To obtain the definition of this constant from
+.\" .IR <ftw.h> ,
+.\" either
+.\" .B _BSD_SOURCE
+.\" must be defined, or
+.\" .BR _XOPEN_SOURCE
+.\" must be defined with a value of 500 or more.
+.TP
+.B FTW_SLN
+.I fpath
+is a symbolic link pointing to a nonexistent file.
+(This occurs only if \fBFTW_PHYS\fP is not set.)
+In this case the
+.I sb
+argument passed to
+.IR fn ()
+contains information returned by performing
+.BR lstat (2)
+on the "dangling" symbolic link.
+(But see BUGS.)
+.P
+The fourth argument
+.RI ( ftwbuf )
+that
+.BR nftw ()
+supplies when calling
+\fIfn\fP()
+is a pointer to a structure of type \fIFTW\fP:
+.P
+.in +4n
+.EX
+struct FTW {
+    int base;
+    int level;
+};
+.EE
+.in
+.P
+.I base
+is the offset of the filename (i.e., basename component)
+in the pathname given in
+.IR fpath .
+.I level
+is the depth of
+.I fpath
+in the directory tree, relative to the root of the tree
+.RI ( dirpath ,
+which has depth 0).
+.P
+To stop the tree walk, \fIfn\fP() returns a nonzero value; this
+value will become the return value of
+.BR nftw ().
+As long as \fIfn\fP() returns 0,
+.BR nftw ()
+will continue either until it has traversed the entire tree,
+in which case it will return zero,
+or until it encounters an error (such as a
+.BR malloc (3)
+failure), in which case it will return \-1.
+.P
+Because
+.BR nftw ()
+uses dynamic data structures, the only safe way to
+exit out of a tree walk is to return a nonzero value from \fIfn\fP().
+To allow a signal to terminate the walk without causing a memory leak,
+have the handler set a global flag that is checked by \fIfn\fP().
+\fIDon't\fP use
+.BR longjmp (3)
+unless the program is going to terminate.
+.P
+The \fIflags\fP argument of
+.BR nftw ()
+is formed by ORing zero or more of the
+following flags:
+.TP
+.BR FTW_ACTIONRETVAL " (since glibc 2.3.3)"
+If this glibc-specific flag is set, then
+.BR nftw ()
+handles the return value from
+.IR fn ()
+differently.
+.IR fn ()
+should return one of the following values:
+.RS
+.TP
+.B FTW_CONTINUE
+Instructs
+.BR nftw ()
+to continue normally.
+.TP
+.B FTW_SKIP_SIBLINGS
+If \fIfn\fP() returns this value, then
+siblings of the current entry will be skipped,
+and processing continues in the parent.
+.\" If \fBFTW_DEPTH\fP
+.\" is set, the entry's parent directory is processed next (with
+.\" \fIflag\fP set to \fBFTW_DP\fP).
+.TP
+.B FTW_SKIP_SUBTREE
+If \fIfn\fP() is called with an entry that is a directory
+(\fItypeflag\fP is \fBFTW_D\fP), this return
+value will prevent objects within that directory from being passed as
+arguments to \fIfn\fP().
+.BR nftw ()
+continues processing with the next sibling of the directory.
+.TP
+.B FTW_STOP
+Causes
+.BR nftw ()
+to return immediately with the return value
+\fBFTW_STOP\fP.
+.P
+Other return values could be associated with new actions in the future;
+\fIfn\fP() should not return values other than those listed above.
+.P
+The feature test macro
+.B _GNU_SOURCE
+must be defined
+(before including
+.I any
+header files)
+in order to
+obtain the definition of \fBFTW_ACTIONRETVAL\fP from \fI<ftw.h>\fP.
+.RE
+.TP
+.B FTW_CHDIR
+If set, do a
+.BR chdir (2)
+to each directory before handling its contents.
+This is useful if the program needs to perform some action
+in the directory in which \fIfpath\fP resides.
+(Specifying this flag has no effect on the pathname that is passed in the
+.I fpath
+argument of
+.IR fn .)
+.TP
+.B FTW_DEPTH
+If set, do a post-order traversal, that is, call \fIfn\fP() for
+the directory itself \fIafter\fP handling the contents of the directory
+and its subdirectories.
+(By default, each directory is handled \fIbefore\fP its contents.)
+.TP
+.B FTW_MOUNT
+If set, stay within the same filesystem
+(i.e., do not cross mount points).
+.TP
+.B FTW_PHYS
+If set, do not follow symbolic links.
+(This is what you want.)
+If not set, symbolic links are followed, but no file is reported twice.
+.IP
+If \fBFTW_PHYS\fP is not set, but \fBFTW_DEPTH\fP is set,
+then the function
+.IR fn ()
+is never called for a directory that would be a descendant of itself.
+.SS ftw()
+.BR ftw ()
+is an older function that offers a subset of the functionality of
+.BR nftw ().
+The notable differences are as follows:
+.IP \[bu] 3
+.BR ftw ()
+has no
+.I flags
+argument.
+It behaves the same as when
+.BR nftw ()
+is called with
+.I flags
+specified as zero.
+.IP \[bu]
+The callback function,
+.IR fn (),
+is not supplied with a fourth argument.
+.IP \[bu]
+The range of values that is passed via the
+.I typeflag
+argument supplied to
+.IR fn ()
+is smaller: just
+.BR FTW_F ,
+.BR FTW_D ,
+.BR FTW_DNR ,
+.BR FTW_NS ,
+and (possibly)
+.BR FTW_SL .
+.SH RETURN VALUE
+These functions return 0 on success, and \-1 if an error occurs.
+.P
+If \fIfn\fP() returns nonzero,
+then the tree walk is terminated and the value returned by \fIfn\fP()
+is returned as the result of
+.BR ftw ()
+or
+.BR nftw ().
+.P
+If
+.BR nftw ()
+is called with the \fBFTW_ACTIONRETVAL\fP flag,
+then the only nonzero value that should be used by \fIfn\fP()
+to terminate the tree walk is \fBFTW_STOP\fP,
+and that value is returned as the result of
+.BR nftw ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR nftw ()
+T}	Thread safety	MT-Safe cwd
+T{
+.na
+.nh
+.BR ftw ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+In some implementations (e.g., glibc),
+.BR ftw ()
+will never use \fBFTW_SL\fP; on other systems \fBFTW_SL\fP occurs only
+for symbolic links that do not point to an existing file;
+and again on other systems
+.BR ftw ()
+will use \fBFTW_SL\fP for each symbolic link.
+If
+.I fpath
+is a symbolic link and
+.BR stat (2)
+failed, POSIX.1-2008 states
+that it is undefined whether \fBFTW_NS\fP or \fBFTW_SL\fP
+is passed in
+.IR typeflag .
+For predictable results, use
+.BR nftw ().
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR ftw ()
+POSIX.1-2001, SVr4, SUSv1.
+POSIX.1-2008 marks it as obsolete.
+.TP
+.BR nftw ()
+glibc 2.1.
+POSIX.1-2001, SUSv1.
+.TP
+.B FTW_SL
+POSIX.1-2001, SUSv1.
+.SH NOTES
+POSIX.1-2008 notes that the results are unspecified if
+.I fn
+does not preserve the current working directory.
+.SH BUGS
+According to POSIX.1-2008, when the
+.I typeflag
+argument passed to
+.IR fn ()
+contains
+.BR FTW_SLN ,
+the buffer pointed to by
+.I sb
+should contain information about the dangling symbolic link
+(obtained by calling
+.BR lstat (2)
+on the link).
+Early glibc versions correctly followed the POSIX specification on this point.
+However, as a result of a regression introduced in glibc 2.4,
+the contents of the buffer pointed to by
+.I sb
+were undefined when
+.B FTW_SLN
+is passed in
+.IR typeflag .
+(More precisely, the contents of the buffer were left unchanged in this case.)
+This regression was eventually fixed in glibc 2.30,
+.\" https://bugzilla.redhat.com/show_bug.cgi?id=1422736
+.\" http://austingroupbugs.net/view.php?id=1121
+.\" glibc commit 6ba205b2c35e3e024c8c12d2ee1b73363e84da87
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=23501
+so that the glibc implementation (once more) follows the POSIX specification.
+.SH EXAMPLES
+The following program traverses the directory tree under the path named
+in its first command-line argument, or under the current directory
+if no argument is supplied.
+It displays various information about each file.
+The second command-line argument can be used to specify characters that
+control the value assigned to the \fIflags\fP
+argument when calling
+.BR nftw ().
+.SS Program source
+\&
+.\" SRC BEGIN (ftw.c)
+.EX
+#define _XOPEN_SOURCE 500
+#include <ftw.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+static int
+display_info(const char *fpath, const struct stat *sb,
+             int tflag, struct FTW *ftwbuf)
+{
+    printf("%\-3s %2d ",
+           (tflag == FTW_D) ?   "d"   : (tflag == FTW_DNR) ? "dnr" :
+           (tflag == FTW_DP) ?  "dp"  : (tflag == FTW_F) ?   "f" :
+           (tflag == FTW_NS) ?  "ns"  : (tflag == FTW_SL) ?  "sl" :
+           (tflag == FTW_SLN) ? "sln" : "???",
+           ftwbuf\->level);
+\&
+    if (tflag == FTW_NS)
+        printf("\-\-\-\-\-\-\-");
+    else
+        printf("%7jd", (intmax_t) sb\->st_size);
+\&
+    printf("   %\-40s %d %s\en",
+           fpath, ftwbuf\->base, fpath + ftwbuf\->base);
+\&
+    return 0;           /* To tell nftw() to continue */
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int flags = 0;
+\&
+    if (argc > 2 && strchr(argv[2], \[aq]d\[aq]) != NULL)
+        flags |= FTW_DEPTH;
+    if (argc > 2 && strchr(argv[2], \[aq]p\[aq]) != NULL)
+        flags |= FTW_PHYS;
+\&
+    if (nftw((argc < 2) ? "." : argv[1], display_info, 20, flags)
+        == \-1)
+    {
+        perror("nftw");
+        exit(EXIT_FAILURE);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR stat (2),
+.BR fts (3),
+.BR readdir (3)
diff --git a/man/man3/funlockfile.3 b/man/man3/funlockfile.3
new file mode 100644
index 000000000..b33c2ee65
--- /dev/null
+++ b/man/man3/funlockfile.3
@@ -0,0 +1 @@
+.so man3/flockfile.3
diff --git a/man/man3/futimens.3 b/man/man3/futimens.3
new file mode 100644
index 000000000..a365c7b53
--- /dev/null
+++ b/man/man3/futimens.3
@@ -0,0 +1 @@
+.so man2/utimensat.2
diff --git a/man/man3/futimes.3 b/man/man3/futimes.3
new file mode 100644
index 000000000..98bb0749c
--- /dev/null
+++ b/man/man3/futimes.3
@@ -0,0 +1,106 @@
+'\" t
+.\" Copyright (c) 2006, 2008, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH futimes 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+futimes, lutimes \- change file timestamps
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/time.h>
+.P
+.BI "int futimes(int " fd ", const struct timeval " tv [2]);
+.BI "int lutimes(const char *" filename ", const struct timeval " tv [2]);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR futimes (),
+.BR lutimes ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR futimes ()
+changes the access and modification times of a file in the same way as
+.BR utimes (2),
+with the difference that the file whose timestamps are to be changed
+is specified via a file descriptor,
+.IR fd ,
+rather than via a pathname.
+.P
+.BR lutimes ()
+changes the access and modification times of a file in the same way as
+.BR utimes (2),
+with the difference that if
+.I filename
+refers to a symbolic link, then the link is not dereferenced:
+instead, the timestamps of the symbolic link are changed.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+Errors are as for
+.BR utimes (2),
+with the following additions for
+.BR futimes ():
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B ENOSYS
+The
+.I /proc
+filesystem could not be accessed.
+.P
+The following additional error may occur for
+.BR lutimes ():
+.TP
+.B ENOSYS
+The kernel does not support this call; Linux 2.6.22 or later is required.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR futimes (),
+.BR lutimes ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+Linux, BSD.
+.SH HISTORY
+.TP
+.BR futimes ()
+glibc 2.3.
+.TP
+.BR lutimes ()
+glibc 2.6.
+.SH NOTES
+.BR lutimes ()
+is implemented using the
+.BR utimensat (2)
+system call.
+.SH SEE ALSO
+.BR utime (2),
+.BR utimensat (2),
+.BR symlink (7)
diff --git a/man/man3/fwide.3 b/man/man3/fwide.3
new file mode 100644
index 000000000..006520aae
--- /dev/null
+++ b/man/man3/fwide.3
@@ -0,0 +1,92 @@
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH fwide 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fwide \- set and determine the orientation of a FILE stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int fwide(FILE *" stream ", int " mode );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fwide ():
+.nf
+    _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE
+        || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+When \fImode\fP is zero, the
+.BR fwide ()
+function determines the current
+orientation of \fIstream\fP.
+It returns a positive value if \fIstream\fP is
+wide-character oriented, that is, if wide-character I/O is permitted but char
+I/O is disallowed.
+It returns a negative value if \fIstream\fP is byte oriented\[em]that is,
+if char I/O is permitted but wide-character I/O is disallowed.
+It
+returns zero if \fIstream\fP has no orientation yet; in this case the next
+I/O operation might change the orientation (to byte oriented if it is a char
+I/O operation, or to wide-character oriented if it is a wide-character I/O
+operation).
+.P
+Once a stream has an orientation, it cannot be changed and persists until
+the stream is closed.
+.P
+When \fImode\fP is nonzero, the
+.BR fwide ()
+function first attempts to set
+\fIstream\fP's orientation (to wide-character oriented
+if \fImode\fP is greater than 0, or
+to byte oriented if \fImode\fP is less than 0).
+It then returns a value denoting the
+current orientation, as above.
+.SH RETURN VALUE
+The
+.BR fwide ()
+function returns the stream's orientation, after possibly
+changing it.
+A positive return value means wide-character oriented.
+A negative return value means byte oriented.
+A return value of zero means undecided.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+Wide-character output to a byte oriented stream can be performed through the
+.BR fprintf (3)
+function with the
+.B %lc
+and
+.B %ls
+directives.
+.P
+Char oriented output to a wide-character oriented stream can be performed
+through the
+.BR fwprintf (3)
+function with the
+.B %c
+and
+.B %s
+directives.
+.SH SEE ALSO
+.BR fprintf (3),
+.BR fwprintf (3)
diff --git a/man/man3/fwprintf.3 b/man/man3/fwprintf.3
new file mode 100644
index 000000000..56ec9685b
--- /dev/null
+++ b/man/man3/fwprintf.3
@@ -0,0 +1 @@
+.so man3/wprintf.3
diff --git a/man/man3/fwrite.3 b/man/man3/fwrite.3
new file mode 100644
index 000000000..86906ede5
--- /dev/null
+++ b/man/man3/fwrite.3
@@ -0,0 +1 @@
+.so man3/fread.3
diff --git a/man/man3/fwrite_unlocked.3 b/man/man3/fwrite_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/fwrite_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/gai_cancel.3 b/man/man3/gai_cancel.3
new file mode 100644
index 000000000..1b0f392ae
--- /dev/null
+++ b/man/man3/gai_cancel.3
@@ -0,0 +1 @@
+.so man3/getaddrinfo_a.3
diff --git a/man/man3/gai_error.3 b/man/man3/gai_error.3
new file mode 100644
index 000000000..1b0f392ae
--- /dev/null
+++ b/man/man3/gai_error.3
@@ -0,0 +1 @@
+.so man3/getaddrinfo_a.3
diff --git a/man/man3/gai_strerror.3 b/man/man3/gai_strerror.3
new file mode 100644
index 000000000..17f7236a7
--- /dev/null
+++ b/man/man3/gai_strerror.3
@@ -0,0 +1 @@
+.so man3/getaddrinfo.3
diff --git a/man/man3/gai_suspend.3 b/man/man3/gai_suspend.3
new file mode 100644
index 000000000..1b0f392ae
--- /dev/null
+++ b/man/man3/gai_suspend.3
@@ -0,0 +1 @@
+.so man3/getaddrinfo_a.3
diff --git a/man/man3/gamma.3 b/man/man3/gamma.3
new file mode 100644
index 000000000..9f0dc9a2d
--- /dev/null
+++ b/man/man3/gamma.3
@@ -0,0 +1,121 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Modified 2003-11-18, aeb: historical remarks
+.\"
+.TH gamma 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gamma, gammaf, gammal \- (logarithm of the) gamma function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "[[deprecated]] double gamma(double " x ");"
+.BI "[[deprecated]] float gammaf(float " x ");"
+.BI "[[deprecated]] long double gammal(long double " x ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR gamma ():
+.nf
+    _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR gammaf (),
+.BR gammal ():
+.nf
+    _XOPEN_SOURCE >= 600 || (_XOPEN_SOURCE && _ISOC99_SOURCE)
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions are deprecated: instead, use either the
+.BR tgamma (3)
+or the
+.BR lgamma (3)
+functions, as appropriate.
+.P
+For the definition of the Gamma function, see
+.BR tgamma (3).
+.SS *BSD version
+The libm in 4.4BSD and some versions of FreeBSD had a
+.BR gamma ()
+function that computes the Gamma function, as one would expect.
+.SS glibc version
+glibc has a
+.BR gamma ()
+function that is equivalent to
+.BR lgamma (3)
+and computes the natural logarithm of the Gamma function.
+.SH RETURN VALUE
+See
+.BR lgamma (3).
+.SH ERRORS
+See
+.BR lgamma (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR gamma (),
+.BR gammaf (),
+.BR gammal ()
+T}	Thread safety	MT-Unsafe race:signgam
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SVID 2.
+.P
+Because of historical variations in behavior across systems,
+this function is not specified in any recent standard.
+.P
+4.2BSD had a
+.BR gamma ()
+that computed
+.RI ln(|Gamma(| x |)|),
+leaving the sign of
+.RI Gamma(| x |)
+in the external integer
+.IR signgam .
+In 4.3BSD the name was changed to
+.BR lgamma (3),
+and the man page promises
+.P
+.in +4n
+"At some time in the future the name gamma will be rehabilitated
+and used for the Gamma function"
+.in
+.P
+This did indeed happen in 4.4BSD, where
+.BR gamma ()
+computes the Gamma function (with no effect on
+.IR signgam ).
+However, this came too late, and we now have
+.BR tgamma (3),
+the "true gamma" function.
+.\" The FreeBSD man page says about gamma() that it is like lgamma()
+.\" except that is does not set signgam.
+.\" Also, that 4.4BSD has a gamma() that computes the true gamma function.
+.SH SEE ALSO
+.BR lgamma (3),
+.BR signgam (3),
+.BR tgamma (3)
diff --git a/man/man3/gammaf.3 b/man/man3/gammaf.3
new file mode 100644
index 000000000..64ab6eec3
--- /dev/null
+++ b/man/man3/gammaf.3
@@ -0,0 +1 @@
+.so man3/gamma.3
diff --git a/man/man3/gammal.3 b/man/man3/gammal.3
new file mode 100644
index 000000000..64ab6eec3
--- /dev/null
+++ b/man/man3/gammal.3
@@ -0,0 +1 @@
+.so man3/gamma.3
diff --git a/man/man3/gcvt.3 b/man/man3/gcvt.3
new file mode 100644
index 000000000..7cdaec33e
--- /dev/null
+++ b/man/man3/gcvt.3
@@ -0,0 +1,82 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:32:25 1993 by Rik Faith (faith@cs.unc.edu)
+.TH gcvt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gcvt \- convert a floating-point number to a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "char *gcvt(double " number ", int " ndigit ", char *" buf );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR gcvt ():
+.nf
+    Since glibc 2.17
+        (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200809L))
+            || /* glibc >= 2.20 */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19 */ _SVID_SOURCE
+    glibc 2.12 to glibc 2.16:
+        (_XOPEN_SOURCE >= 500 && ! (_POSIX_C_SOURCE >= 200112L))
+            || _SVID_SOURCE
+    Before glibc 2.12:
+        _SVID_SOURCE || _XOPEN_SOURCE >= 500
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+The
+.BR gcvt ()
+function converts \fInumber\fP to a minimal length null-terminated
+ASCII string and stores the result in \fIbuf\fP.
+It produces \fIndigit\fP significant digits in either
+.BR printf (3)
+F format or E format.
+.SH RETURN VALUE
+The
+.BR gcvt ()
+function returns
+\fIbuf\fP.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR gcvt ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+Marked as LEGACY in POSIX.1-2001.
+POSIX.1-2008 removed it,
+recommending the use of
+.BR sprintf (3)
+instead (though
+.BR snprintf (3)
+may be preferable).
+.SH SEE ALSO
+.BR ecvt (3),
+.BR fcvt (3),
+.BR sprintf (3)
diff --git a/man/man3/get_avphys_pages.3 b/man/man3/get_avphys_pages.3
new file mode 100644
index 000000000..cbd22ccff
--- /dev/null
+++ b/man/man3/get_avphys_pages.3
@@ -0,0 +1 @@
+.so man3/get_phys_pages.3
diff --git a/man/man3/get_current_dir_name.3 b/man/man3/get_current_dir_name.3
new file mode 100644
index 000000000..f73c1579c
--- /dev/null
+++ b/man/man3/get_current_dir_name.3
@@ -0,0 +1 @@
+.so man3/getcwd.3
diff --git a/man/man3/get_myaddress.3 b/man/man3/get_myaddress.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/get_myaddress.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/get_nprocs.3 b/man/man3/get_nprocs.3
new file mode 100644
index 000000000..49605f99a
--- /dev/null
+++ b/man/man3/get_nprocs.3
@@ -0,0 +1,93 @@
+'\" t
+.\" Copyright (c) 2012, Petr Benas
+.\" and Copyright (c) 2012, Michael Kerrisk <mtk.man-pages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH get_nprocs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+get_nprocs, get_nprocs_conf \- get number of processors
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/sysinfo.h>
+.P
+.B int get_nprocs(void);
+.B int get_nprocs_conf(void);
+.fi
+.SH DESCRIPTION
+The function
+.BR get_nprocs_conf ()
+returns the number of processors configured by the operating system.
+.P
+The function
+.BR get_nprocs ()
+returns the number of processors currently available in the system.
+This may be less than the number returned by
+.BR get_nprocs_conf ()
+because processors may be offline (e.g., on hotpluggable systems).
+.SH RETURN VALUE
+As given in DESCRIPTION.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR get_nprocs (),
+.BR get_nprocs_conf ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH NOTES
+The current
+.\" glibc 2.15
+implementation of these functions is rather expensive,
+since they open and parse files in the
+.I /sys
+filesystem each time they are called.
+.P
+The following
+.BR sysconf (3)
+calls make use of the functions documented on this page
+to return the same information.
+.P
+.in +4n
+.EX
+np = sysconf(_SC_NPROCESSORS_CONF);     /* processors configured */
+np = sysconf(_SC_NPROCESSORS_ONLN);     /* processors available */
+.EE
+.in
+.SH EXAMPLES
+The following example shows how
+.BR get_nprocs ()
+and
+.BR get_nprocs_conf ()
+can be used.
+.P
+.\" SRC BEGIN (get_nprocs_conf.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/sysinfo.h>
+\&
+int
+main(void)
+{
+    printf("This system has %d processors configured and "
+            "%d processors available.\en",
+            get_nprocs_conf(), get_nprocs());
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR nproc (1)
diff --git a/man/man3/get_nprocs_conf.3 b/man/man3/get_nprocs_conf.3
new file mode 100644
index 000000000..7de3e2b31
--- /dev/null
+++ b/man/man3/get_nprocs_conf.3
@@ -0,0 +1 @@
+.so man3/get_nprocs.3
diff --git a/man/man3/get_phys_pages.3 b/man/man3/get_phys_pages.3
new file mode 100644
index 000000000..a2a627a8c
--- /dev/null
+++ b/man/man3/get_phys_pages.3
@@ -0,0 +1,90 @@
+.\" Copyright (c) 2015 William Woodruff (william@tuffbizz.com)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH get_phys_pages 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+get_phys_pages, get_avphys_pages \- get total and available physical
+page counts
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <sys/sysinfo.h>"
+.P
+.B long get_phys_pages(void);
+.B long get_avphys_pages(void);
+.fi
+.SH DESCRIPTION
+The function
+.BR get_phys_pages ()
+returns the total number of physical pages of memory available on the system.
+.P
+The function
+.BR get_avphys_pages ()
+returns the number of currently available physical pages of memory on the
+system.
+.SH RETURN VALUE
+On success,
+these functions return a nonnegative value as given in DESCRIPTION.
+On failure, they return \-1 and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B ENOSYS
+The system could not provide the required information
+(possibly because the
+.I /proc
+filesystem was not mounted).
+.SH STANDARDS
+GNU.
+.SH HISTORY
+Before glibc 2.23,
+these functions obtained the required information by scanning the
+.I MemTotal
+and
+.I MemFree
+fields of
+.IR /proc/meminfo .
+Since glibc 2.23,
+these functions obtain the required information by calling
+.BR sysinfo (2).
+.SH NOTES
+The following
+.BR sysconf (3)
+calls provide a portable means of obtaining the same information as the
+functions described on this page.
+.P
+.in +4n
+.EX
+total_pages = sysconf(_SC_PHYS_PAGES);    /* total pages */
+avl_pages = sysconf(_SC_AVPHYS_PAGES);    /* available pages */
+.EE
+.in
+.SH EXAMPLES
+The following example shows how
+.BR get_phys_pages ()
+and
+.BR get_avphys_pages ()
+can be used.
+.P
+.\" SRC BEGIN (get_phys_pages.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/sysinfo.h>
+\&
+int
+main(void)
+{
+    printf("This system has %ld pages of physical memory and "
+            "%ld pages of physical memory available.\en",
+            get_phys_pages(), get_avphys_pages());
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR sysconf (3)
diff --git a/man/man3/getaddrinfo.3 b/man/man3/getaddrinfo.3
new file mode 100644
index 000000000..beb643460
--- /dev/null
+++ b/man/man3/getaddrinfo.3
@@ -0,0 +1,854 @@
+'\" t
+.\" Copyright (c) 2007, 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (c) 2006 Ulrich Drepper <drepper@redhat.com>
+.\" A few pieces of an earlier version remain:
+.\" Copyright 2000, Sam Varshavchik <mrsam@courier-mta.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References: RFC 2553
+.\"
+.\" 2005-08-09, mtk, added AI_ALL, AI_ADDRCONFIG, AI_V4MAPPED,
+.\"			and AI_NUMERICSERV.
+.\" 2006-11-25, Ulrich Drepper <drepper@redhat.com>
+.\"     Add text describing Internationalized Domain Name extensions.
+.\" 2007-06-08, mtk: added example programs
+.\" 2008-02-26, mtk; clarify discussion of NULL 'hints' argument; other
+.\"     minor rewrites.
+.\" 2008-06-18, mtk: many parts rewritten
+.\" 2008-12-04, Petr Baudis <pasky@suse.cz>
+.\"	Describe results ordering and reference /etc/gai.conf.
+.\"
+.\" FIXME . glibc's 2.9 NEWS file documents DCCP and UDP-lite support
+.\"           and is SCTP support now also there?
+.\"
+.TH getaddrinfo 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getaddrinfo, freeaddrinfo, gai_strerror \- network address and
+service translation
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <sys/socket.h>
+.B #include <netdb.h>
+.P
+.BI "int getaddrinfo(const char *restrict " node ,
+.BI "                const char *restrict " service ,
+.BI "                const struct addrinfo *restrict " hints ,
+.BI "                struct addrinfo **restrict " res );
+.P
+.BI "void freeaddrinfo(struct addrinfo *" res );
+.P
+.BI "const char *gai_strerror(int " errcode );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getaddrinfo (),
+.BR freeaddrinfo (),
+.BR gai_strerror ():
+.nf
+    Since glibc 2.22:
+        _POSIX_C_SOURCE >= 200112L
+    glibc 2.21 and earlier:
+        _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+Given
+.I node
+and
+.IR service ,
+which identify an Internet host and a service,
+.BR getaddrinfo ()
+returns one or more
+.I addrinfo
+structures, each of which contains an Internet address
+that can be specified in a call to
+.BR bind (2)
+or
+.BR connect (2).
+The
+.BR getaddrinfo ()
+function combines the functionality provided by the
+.\" .BR getipnodebyname (3),
+.\" .BR getipnodebyaddr (3),
+.BR gethostbyname (3)
+and
+.BR getservbyname (3)
+functions into a single interface, but unlike the latter functions,
+.BR getaddrinfo ()
+is reentrant and allows programs to eliminate IPv4-versus-IPv6 dependencies.
+.P
+The
+.I addrinfo
+structure used by
+.BR getaddrinfo ()
+contains the following fields:
+.P
+.in +4n
+.EX
+struct addrinfo {
+    int              ai_flags;
+    int              ai_family;
+    int              ai_socktype;
+    int              ai_protocol;
+    socklen_t        ai_addrlen;
+    struct sockaddr *ai_addr;
+    char            *ai_canonname;
+    struct addrinfo *ai_next;
+};
+.EE
+.in
+.P
+The
+.I hints
+argument points to an
+.I addrinfo
+structure that specifies criteria for selecting the socket address
+structures returned in the list pointed to by
+.IR res .
+If
+.I hints
+is not NULL it points to an
+.I addrinfo
+structure whose
+.IR ai_family ,
+.IR ai_socktype ,
+and
+.I ai_protocol
+specify criteria that limit the set of socket addresses returned by
+.BR getaddrinfo (),
+as follows:
+.TP
+.I ai_family
+This field specifies the desired address family for the returned addresses.
+Valid values for this field include
+.B AF_INET
+and
+.BR AF_INET6 .
+The value
+.B AF_UNSPEC
+indicates that
+.BR getaddrinfo ()
+should return socket addresses for any address family
+(either IPv4 or IPv6, for example) that can be used with
+.I node
+and
+.IR service .
+.TP
+.I ai_socktype
+This field specifies the preferred socket type, for example
+.B SOCK_STREAM
+or
+.BR SOCK_DGRAM .
+Specifying 0 in this field indicates that socket addresses of any type
+can be returned by
+.BR getaddrinfo ().
+.TP
+.I ai_protocol
+This field specifies the protocol for the returned socket addresses.
+Specifying 0 in this field indicates that socket addresses with
+any protocol can be returned by
+.BR getaddrinfo ().
+.TP
+.I ai_flags
+This field specifies additional options, described below.
+Multiple flags are specified by bitwise OR-ing them together.
+.P
+All the other fields in the structure pointed to by
+.I hints
+must contain either 0 or a null pointer, as appropriate.
+.P
+Specifying
+.I hints
+as NULL is equivalent to setting
+.I ai_socktype
+and
+.I ai_protocol
+to 0;
+.I ai_family
+to
+.BR AF_UNSPEC ;
+and
+.I ai_flags
+to
+.BR "(AI_V4MAPPED\ |\ AI_ADDRCONFIG)" .
+(POSIX specifies different defaults for
+.IR ai_flags ;
+see NOTES.)
+.I node
+specifies either a numerical network address
+(for IPv4, numbers-and-dots notation as supported by
+.BR inet_aton (3);
+for IPv6, hexadecimal string format as supported by
+.BR inet_pton (3)),
+or a network hostname, whose network addresses are looked up and resolved.
+If
+.I hints.ai_flags
+contains the
+.B AI_NUMERICHOST
+flag, then
+.I node
+must be a numerical network address.
+The
+.B AI_NUMERICHOST
+flag suppresses any potentially lengthy network host address lookups.
+.P
+If the
+.B AI_PASSIVE
+flag is specified in
+.IR hints.ai_flags ,
+and
+.I node
+is NULL,
+then the returned socket addresses will be suitable for
+.BR bind (2)ing
+a socket that will
+.BR accept (2)
+connections.
+The returned socket address will contain the "wildcard address"
+.RB ( INADDR_ANY
+for IPv4 addresses,
+.B IN6ADDR_ANY_INIT
+for IPv6 address).
+The wildcard address is used by applications (typically servers)
+that intend to accept connections on any of the host's network addresses.
+If
+.I node
+is not NULL, then the
+.B AI_PASSIVE
+flag is ignored.
+.P
+If the
+.B AI_PASSIVE
+flag is not set in
+.IR hints.ai_flags ,
+then the returned socket addresses will be suitable for use with
+.BR connect (2),
+.BR sendto (2),
+or
+.BR sendmsg (2).
+If
+.I node
+is NULL,
+then the network address will be set to the loopback interface address
+.RB ( INADDR_LOOPBACK
+for IPv4 addresses,
+.B IN6ADDR_LOOPBACK_INIT
+for IPv6 address);
+this is used by applications that intend to communicate
+with peers running on the same host.
+.P
+.I service
+sets the port in each returned address structure.
+If this argument is a service name (see
+.BR services (5)),
+it is translated to the corresponding port number.
+This argument can also be specified as a decimal number,
+which is simply converted to binary.
+If
+.I service
+is NULL, then the port number of the returned socket addresses
+will be left uninitialized.
+If
+.B AI_NUMERICSERV
+is specified in
+.I hints.ai_flags
+and
+.I service
+is not NULL, then
+.I service
+must point to a string containing a numeric port number.
+This flag is used to inhibit the invocation of a name resolution service
+in cases where it is known not to be required.
+.P
+Either
+.I node
+or
+.IR service ,
+but not both, may be NULL.
+.P
+The
+.BR getaddrinfo ()
+function allocates and initializes a linked list of
+.I addrinfo
+structures, one for each network address that matches
+.I node
+and
+.IR service ,
+subject to any restrictions imposed by
+.IR hints ,
+and returns a pointer to the start of the list in
+.IR res .
+The items in the linked list are linked by the
+.I ai_next
+field.
+.P
+There are several reasons why
+the linked list may have more than one
+.I addrinfo
+structure, including: the network host is multihomed, accessible
+over multiple protocols (e.g., both
+.B AF_INET
+and
+.BR AF_INET6 );
+or the same service is available from multiple socket types (one
+.B SOCK_STREAM
+address and another
+.B SOCK_DGRAM
+address, for example).
+Normally, the application should try
+using the addresses in the order in which they are returned.
+The sorting function used within
+.BR getaddrinfo ()
+is defined in RFC\ 3484; the order can be tweaked for a particular
+system by editing
+.I /etc/gai.conf
+(available since glibc 2.5).
+.P
+If
+.I hints.ai_flags
+includes the
+.B AI_CANONNAME
+flag, then the
+.I ai_canonname
+field of the first of the
+.I addrinfo
+structures in the returned list is set to point to the
+official name of the host.
+.\" Prior to glibc 2.3.4, the ai_canonname of each addrinfo
+.\" structure was set pointing to the canonical name; that was
+.\" more than POSIX.1-2001 specified, or other implementations provided.
+.\" MTK, Aug 05
+.P
+The remaining fields of each returned
+.I addrinfo
+structure are initialized as follows:
+.IP \[bu] 3
+The
+.IR ai_family ,
+.IR ai_socktype ,
+and
+.I ai_protocol
+fields return the socket creation parameters (i.e., these fields have
+the same meaning as the corresponding arguments of
+.BR socket (2)).
+For example,
+.I ai_family
+might return
+.B AF_INET
+or
+.BR AF_INET6 ;
+.I ai_socktype
+might return
+.B SOCK_DGRAM
+or
+.BR SOCK_STREAM ;
+and
+.I ai_protocol
+returns the protocol for the socket.
+.IP \[bu]
+A pointer to the socket address is placed in the
+.I ai_addr
+field, and the length of the socket address, in bytes,
+is placed in the
+.I ai_addrlen
+field.
+.P
+If
+.I hints.ai_flags
+includes the
+.B AI_ADDRCONFIG
+flag, then IPv4 addresses are returned in the list pointed to by
+.I res
+only if the local system has at least one
+IPv4 address configured, and IPv6 addresses are returned
+only if the local system has at least one IPv6 address configured.
+The loopback address is not considered for this case as valid
+as a configured address.
+This flag is useful on, for example,
+IPv4-only systems, to ensure that
+.BR getaddrinfo ()
+does not return IPv6 socket addresses that would always fail in
+.BR connect (2)
+or
+.BR bind (2).
+.P
+If
+.I hints.ai_flags
+specifies the
+.B AI_V4MAPPED
+flag, and
+.I hints.ai_family
+was specified as
+.BR AF_INET6 ,
+and no matching IPv6 addresses could be found,
+then return IPv4-mapped IPv6 addresses in the list pointed to by
+.IR res .
+If both
+.B AI_V4MAPPED
+and
+.B AI_ALL
+are specified in
+.IR hints.ai_flags ,
+then return both IPv6 and IPv4-mapped IPv6 addresses
+in the list pointed to by
+.IR res .
+.B AI_ALL
+is ignored if
+.B AI_V4MAPPED
+is not also specified.
+.P
+The
+.BR freeaddrinfo ()
+function frees the memory that was allocated
+for the dynamically allocated linked list
+.IR res .
+.SS Extensions to getaddrinfo() for Internationalized Domain Names
+Starting with glibc 2.3.4,
+.BR getaddrinfo ()
+has been extended to selectively allow the incoming and outgoing
+hostnames to be transparently converted to and from the
+Internationalized Domain Name (IDN) format (see RFC 3490,
+.IR "Internationalizing Domain Names in Applications (IDNA)" ).
+Four new flags are defined:
+.TP
+.B AI_IDN
+If this flag is specified, then the node name given in
+.I node
+is converted to IDN format if necessary.
+The source encoding is that of the current locale.
+.IP
+If the input name contains non-ASCII characters, then the IDN encoding
+is used.
+Those parts of the node name (delimited by dots) that contain
+non-ASCII characters are encoded using ASCII Compatible Encoding (ACE)
+before being passed to the name resolution functions.
+.\" Implementation Detail:
+.\" To minimize effects on system performance the implementation might
+.\" want to check whether the input string contains any non-ASCII
+.\" characters.  If there are none the IDN step can be skipped completely.
+.\" On systems which allow not-ASCII safe encodings for a locale this
+.\" might be a problem.
+.TP
+.B AI_CANONIDN
+After a successful name lookup, and if the
+.B AI_CANONNAME
+flag was specified,
+.BR getaddrinfo ()
+will return the canonical name of the
+node corresponding to the
+.I addrinfo
+structure value passed back.
+The return value is an exact copy of the value returned by the name
+resolution function.
+.IP
+If the name is encoded using ACE, then it will contain the
+.I xn\-\-
+prefix for one or more components of the name.
+To convert these components into a readable form the
+.B AI_CANONIDN
+flag can be passed in addition to
+.BR AI_CANONNAME .
+The resulting string is encoded using the current locale's encoding.
+.\"
+.\"Implementation Detail:
+.\"If no component of the returned name starts with xn\-\- the IDN
+.\"step can be skipped, therefore avoiding unnecessary slowdowns.
+.TP
+.B AI_IDN_ALLOW_UNASSIGNED
+.TQ
+.B AI_IDN_USE_STD3_ASCII_RULES
+Setting these flags will enable the
+IDNA_ALLOW_UNASSIGNED (allow unassigned Unicode code points) and
+IDNA_USE_STD3_ASCII_RULES (check output to make sure it is a STD3
+conforming hostname)
+flags respectively to be used in the IDNA handling.
+.SH RETURN VALUE
+.\" FIXME glibc defines the following additional errors, some which
+.\" can probably be returned by getaddrinfo(); they need to
+.\" be documented.
+.\"    #ifdef __USE_GNU
+.\"    #define EAI_INPROGRESS  -100  /* Processing request in progress.  */
+.\"    #define EAI_CANCELED    -101  /* Request canceled.  */
+.\"    #define EAI_NOTCANCELED -102  /* Request not canceled.  */
+.\"    #define EAI_ALLDONE     -103  /* All requests done.  */
+.\"    #define EAI_INTR        -104  /* Interrupted by a signal.  */
+.\"    #define EAI_IDN_ENCODE  -105  /* IDN encoding failed.  */
+.\"    #endif
+.BR getaddrinfo ()
+returns 0 if it succeeds, or one of the following nonzero error codes:
+.TP
+.B EAI_ADDRFAMILY
+.\" Not in SUSv3
+The specified network host does not have any network addresses in the
+requested address family.
+.TP
+.B EAI_AGAIN
+The name server returned a temporary failure indication.
+Try again later.
+.TP
+.B EAI_BADFLAGS
+.I hints.ai_flags
+contains invalid flags; or,
+.I hints.ai_flags
+included
+.B AI_CANONNAME
+and
+.I node
+was NULL.
+.TP
+.B EAI_FAIL
+The name server returned a permanent failure indication.
+.TP
+.B EAI_FAMILY
+The requested address family is not supported.
+.TP
+.B EAI_MEMORY
+Out of memory.
+.TP
+.B EAI_NODATA
+.\" Not in SUSv3
+The specified network host exists, but does not have any
+network addresses defined.
+.TP
+.B EAI_NONAME
+The
+.I node
+or
+.I service
+is not known; or both
+.I node
+and
+.I service
+are NULL; or
+.B AI_NUMERICSERV
+was specified in
+.I hints.ai_flags
+and
+.I service
+was not a numeric port-number string.
+.TP
+.B EAI_SERVICE
+The requested service is not available for the requested socket type.
+It may be available through another socket type.
+For example, this error could occur if
+.I service
+was "shell" (a service available only on stream sockets), and either
+.I hints.ai_protocol
+was
+.BR IPPROTO_UDP ,
+or
+.I hints.ai_socktype
+was
+.BR SOCK_DGRAM ;
+or the error could occur if
+.I service
+was not NULL, and
+.I hints.ai_socktype
+was
+.B SOCK_RAW
+(a socket type that does not support the concept of services).
+.TP
+.B EAI_SOCKTYPE
+The requested socket type is not supported.
+This could occur, for example, if
+.I hints.ai_socktype
+and
+.I hints.ai_protocol
+are inconsistent (e.g.,
+.B SOCK_DGRAM
+and
+.BR IPPROTO_TCP ,
+respectively).
+.TP
+.B EAI_SYSTEM
+Other system error;
+.I errno
+is set to indicate the error.
+.P
+The
+.BR gai_strerror ()
+function translates these error codes to a human readable string,
+suitable for error reporting.
+.SH FILES
+.I /etc/gai.conf
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getaddrinfo ()
+T}	Thread safety	MT-Safe env locale
+T{
+.na
+.nh
+.BR freeaddrinfo (),
+.BR gai_strerror ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+According to POSIX.1, specifying
+.\" POSIX.1-2001, POSIX.1-2008
+.I hints
+as NULL should cause
+.I ai_flags
+to be assumed as 0.
+The GNU C library instead assumes a value of
+.B (AI_V4MAPPED\~|\~AI_ADDRCONFIG)
+for this case,
+since this value is considered an improvement on the specification.
+.SH STANDARDS
+POSIX.1-2008.
+.TP
+.BR getaddrinfo ()
+RFC\ 2553.
+.SH HISTORY
+POSIX.1-2001.
+.TP
+.B AI_ADDRCONFIG
+.TQ
+.B AI_ALL
+.TQ
+.B AI_V4MAPPED
+glibc 2.3.3.
+.TP
+.B AI_NUMERICSERV
+glibc 2.3.4.
+.SH NOTES
+.BR getaddrinfo ()
+supports the
+.IB address % scope-id
+notation for specifying the IPv6 scope-ID.
+.SH EXAMPLES
+.\" getnameinfo.3 refers to this example
+.\" socket.2 refers to this example
+.\" bind.2 refers to this example
+.\" connect.2 refers to this example
+.\" recvfrom.2 refers to this example
+.\" sendto.2 refers to this example
+The following programs demonstrate the use of
+.BR getaddrinfo (),
+.BR gai_strerror (),
+.BR freeaddrinfo (),
+and
+.BR getnameinfo (3).
+The programs are an echo server and client for UDP datagrams.
+.SS Server program
+\&
+.\" SRC BEGIN (server.c)
+.EX
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+\&
+#define BUF_SIZE 500
+\&
+int
+main(int argc, char *argv[])
+{
+    int                      sfd, s;
+    char                     buf[BUF_SIZE];
+    ssize_t                  nread;
+    socklen_t                peer_addrlen;
+    struct addrinfo          hints;
+    struct addrinfo          *result, *rp;
+    struct sockaddr_storage  peer_addr;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s port\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = AF_UNSPEC;    /* Allow IPv4 or IPv6 */
+    hints.ai_socktype = SOCK_DGRAM; /* Datagram socket */
+    hints.ai_flags = AI_PASSIVE;    /* For wildcard IP address */
+    hints.ai_protocol = 0;          /* Any protocol */
+    hints.ai_canonname = NULL;
+    hints.ai_addr = NULL;
+    hints.ai_next = NULL;
+\&
+    s = getaddrinfo(NULL, argv[1], &hints, &result);
+    if (s != 0) {
+        fprintf(stderr, "getaddrinfo: %s\en", gai_strerror(s));
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* getaddrinfo() returns a list of address structures.
+       Try each address until we successfully bind(2).
+       If socket(2) (or bind(2)) fails, we (close the socket
+       and) try the next address. */
+\&
+    for (rp = result; rp != NULL; rp = rp\->ai_next) {
+        sfd = socket(rp\->ai_family, rp\->ai_socktype,
+                     rp\->ai_protocol);
+        if (sfd == \-1)
+            continue;
+\&
+        if (bind(sfd, rp\->ai_addr, rp\->ai_addrlen) == 0)
+            break;                  /* Success */
+\&
+        close(sfd);
+    }
+\&
+    freeaddrinfo(result);           /* No longer needed */
+\&
+    if (rp == NULL) {               /* No address succeeded */
+        fprintf(stderr, "Could not bind\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Read datagrams and echo them back to sender. */
+\&
+    for (;;) {
+        char host[NI_MAXHOST], service[NI_MAXSERV];
+\&
+        peer_addrlen = sizeof(peer_addr);
+        nread = recvfrom(sfd, buf, BUF_SIZE, 0,
+                         (struct sockaddr *) &peer_addr, &peer_addrlen);
+        if (nread == \-1)
+            continue;               /* Ignore failed request */
+\&
+        s = getnameinfo((struct sockaddr *) &peer_addr,
+                        peer_addrlen, host, NI_MAXHOST,
+                        service, NI_MAXSERV, NI_NUMERICSERV);
+        if (s == 0)
+            printf("Received %zd bytes from %s:%s\en",
+                   nread, host, service);
+        else
+            fprintf(stderr, "getnameinfo: %s\en", gai_strerror(s));
+\&
+        if (sendto(sfd, buf, nread, 0, (struct sockaddr *) &peer_addr,
+                   peer_addrlen) != nread)
+        {
+            fprintf(stderr, "Error sending response\en");
+        }
+    }
+}
+.EE
+.\" SRC END
+.SS Client program
+\&
+.\" SRC BEGIN (client.c)
+.EX
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+\&
+#define BUF_SIZE 500
+\&
+int
+main(int argc, char *argv[])
+{
+    int              sfd, s;
+    char             buf[BUF_SIZE];
+    size_t           len;
+    ssize_t          nread;
+    struct addrinfo  hints;
+    struct addrinfo  *result, *rp;
+\&
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s host port msg...\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Obtain address(es) matching host/port. */
+\&
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = AF_UNSPEC;    /* Allow IPv4 or IPv6 */
+    hints.ai_socktype = SOCK_DGRAM; /* Datagram socket */
+    hints.ai_flags = 0;
+    hints.ai_protocol = 0;          /* Any protocol */
+\&
+    s = getaddrinfo(argv[1], argv[2], &hints, &result);
+    if (s != 0) {
+        fprintf(stderr, "getaddrinfo: %s\en", gai_strerror(s));
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* getaddrinfo() returns a list of address structures.
+       Try each address until we successfully connect(2).
+       If socket(2) (or connect(2)) fails, we (close the socket
+       and) try the next address. */
+\&
+    for (rp = result; rp != NULL; rp = rp\->ai_next) {
+        sfd = socket(rp\->ai_family, rp\->ai_socktype,
+                     rp\->ai_protocol);
+        if (sfd == \-1)
+            continue;
+\&
+        if (connect(sfd, rp\->ai_addr, rp\->ai_addrlen) != \-1)
+            break;                  /* Success */
+\&
+        close(sfd);
+    }
+\&
+    freeaddrinfo(result);           /* No longer needed */
+\&
+    if (rp == NULL) {               /* No address succeeded */
+        fprintf(stderr, "Could not connect\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Send remaining command\-line arguments as separate
+       datagrams, and read responses from server. */
+\&
+    for (size_t j = 3; j < argc; j++) {
+        len = strlen(argv[j]) + 1;
+                /* +1 for terminating null byte */
+\&
+        if (len > BUF_SIZE) {
+            fprintf(stderr,
+                    "Ignoring long message in argument %zu\en", j);
+            continue;
+        }
+\&
+        if (write(sfd, argv[j], len) != len) {
+            fprintf(stderr, "partial/failed write\en");
+            exit(EXIT_FAILURE);
+        }
+\&
+        nread = read(sfd, buf, BUF_SIZE);
+        if (nread == \-1) {
+            perror("read");
+            exit(EXIT_FAILURE);
+        }
+\&
+        printf("Received %zd bytes: %s\en", nread, buf);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.\" .BR getipnodebyaddr (3),
+.\" .BR getipnodebyname (3),
+.BR getaddrinfo_a (3),
+.BR gethostbyname (3),
+.BR getnameinfo (3),
+.BR inet (3),
+.BR gai.conf (5),
+.BR hostname (7),
+.BR ip (7)
diff --git a/man/man3/getaddrinfo_a.3 b/man/man3/getaddrinfo_a.3
new file mode 100644
index 000000000..e7792fd76
--- /dev/null
+++ b/man/man3/getaddrinfo_a.3
@@ -0,0 +1,645 @@
+'\" t
+.\" Copyright (c) 2009 Petr Baudis <pasky@suse.cz>
+.\" and clean-ups and additions (C) Copyright 2010 Michael Kerrisk
+.\"                                 <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References: http://people.redhat.com/drepper/asynchnl.pdf,
+.\"     http://www.imperialviolet.org/2005/06/01/asynchronous-dns-lookups-with-glibc.html
+.\"
+.TH getaddrinfo_a 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getaddrinfo_a, gai_suspend, gai_error, gai_cancel \- asynchronous
+network address and service translation
+.SH LIBRARY
+Asynchronous name lookup library
+.RI ( libanl ", " \-lanl )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <netdb.h>
+.P
+.BI "int getaddrinfo_a(int " mode ", struct gaicb *" list [restrict],
+.BI "                  int " nitems ", struct sigevent *restrict " sevp );
+.BI "int gai_suspend(const struct gaicb *const " list "[], int " nitems ,
+.BI "                  const struct timespec *" timeout );
+.P
+.BI "int gai_error(struct gaicb *" req );
+.BI "int gai_cancel(struct gaicb *" req );
+.fi
+.SH DESCRIPTION
+The
+.BR getaddrinfo_a ()
+function performs the same task as
+.BR getaddrinfo (3),
+but allows multiple name look-ups to be performed asynchronously,
+with optional notification on completion of look-up operations.
+.P
+The
+.I mode
+argument has one of the following values:
+.TP
+.B GAI_WAIT
+Perform the look-ups synchronously.
+The call blocks until the look-ups have completed.
+.TP
+.B GAI_NOWAIT
+Perform the look-ups asynchronously.
+The call returns immediately,
+and the requests are resolved in the background.
+See the discussion of the
+.I sevp
+argument below.
+.P
+The array
+.I list
+specifies the look-up requests to process.
+The
+.I nitems
+argument specifies the number of elements in
+.IR list .
+The requested look-up operations are started in parallel.
+NULL elements in
+.I list
+are ignored.
+Each request is described by a
+.I gaicb
+structure, defined as follows:
+.P
+.in +4n
+.EX
+struct gaicb {
+    const char            *ar_name;
+    const char            *ar_service;
+    const struct addrinfo *ar_request;
+    struct addrinfo       *ar_result;
+};
+.EE
+.in
+.P
+The elements of this structure correspond to the arguments of
+.BR getaddrinfo (3).
+Thus,
+.I ar_name
+corresponds to the
+.I node
+argument and
+.I ar_service
+to the
+.I service
+argument, identifying an Internet host and a service.
+The
+.I ar_request
+element corresponds to the
+.I hints
+argument, specifying the criteria for selecting
+the returned socket address structures.
+Finally,
+.I ar_result
+corresponds to the
+.I res
+argument; you do not need to initialize this element,
+it will be automatically set when the request
+is resolved.
+The
+.I addrinfo
+structure referenced by the last two elements is described in
+.BR getaddrinfo (3).
+.P
+When
+.I mode
+is specified as
+.BR GAI_NOWAIT ,
+notifications about resolved requests
+can be obtained by employing the
+.I sigevent
+structure pointed to by the
+.I sevp
+argument.
+For the definition and general details of this structure, see
+.BR sigevent (3type).
+The
+.I sevp\->sigev_notify
+field can have the following values:
+.TP
+.B SIGEV_NONE
+Don't provide any notification.
+.TP
+.B SIGEV_SIGNAL
+When a look-up completes, generate the signal
+.I sigev_signo
+for the process.
+See
+.BR sigevent (3type)
+for general details.
+The
+.I si_code
+field of the
+.I siginfo_t
+structure will be set to
+.BR SI_ASYNCNL .
+.\" si_pid and si_uid are also set, to the values of the calling process,
+.\" which doesn't provide useful information, so we'll skip mentioning it.
+.TP
+.B SIGEV_THREAD
+When a look-up completes, invoke
+.I sigev_notify_function
+as if it were the start function of a new thread.
+See
+.BR sigevent (3type)
+for details.
+.P
+For
+.B SIGEV_SIGNAL
+and
+.BR SIGEV_THREAD ,
+it may be useful to point
+.I sevp\->sigev_value.sival_ptr
+to
+.IR list .
+.P
+The
+.BR gai_suspend ()
+function suspends execution of the calling thread,
+waiting for the completion of one or more requests in the array
+.IR list .
+The
+.I nitems
+argument specifies the size of the array
+.IR list .
+The call blocks until one of the following occurs:
+.IP \[bu] 3
+One or more of the operations in
+.I list
+completes.
+.IP \[bu]
+The call is interrupted by a signal that is caught.
+.IP \[bu]
+The time interval specified in
+.I timeout
+elapses.
+This argument specifies a timeout in seconds plus nanoseconds (see
+.BR nanosleep (2)
+for details of the
+.I timespec
+structure).
+If
+.I timeout
+is NULL, then the call blocks indefinitely
+(until one of the events above occurs).
+.P
+No explicit indication of which request was completed is given;
+you must determine which request(s) have completed by iterating with
+.BR gai_error ()
+over the list of requests.
+.P
+The
+.BR gai_error ()
+function returns the status of the request
+.IR req :
+either
+.B EAI_INPROGRESS
+if the request was not completed yet,
+0 if it was handled successfully,
+or an error code if the request could not be resolved.
+.P
+The
+.BR gai_cancel ()
+function cancels the request
+.IR req .
+If the request has been canceled successfully,
+the error status of the request will be set to
+.B EAI_CANCELED
+and normal asynchronous notification will be performed.
+The request cannot be canceled if it is currently being processed;
+in that case, it will be handled as if
+.BR gai_cancel ()
+has never been called.
+If
+.I req
+is NULL, an attempt is made to cancel all outstanding requests
+that the process has made.
+.SH RETURN VALUE
+The
+.BR getaddrinfo_a ()
+function returns 0 if all of the requests have been enqueued successfully,
+or one of the following nonzero error codes:
+.TP
+.B EAI_AGAIN
+The resources necessary to enqueue the look-up requests were not available.
+The application may check the error status of each
+request to determine which ones failed.
+.TP
+.B EAI_MEMORY
+Out of memory.
+.TP
+.B EAI_SYSTEM
+.I mode
+is invalid.
+.P
+The
+.BR gai_suspend ()
+function returns 0 if at least one of the listed requests has been completed.
+Otherwise, it returns one of the following nonzero error codes:
+.TP
+.B EAI_AGAIN
+The given timeout expired before any of the requests could be completed.
+.TP
+.B EAI_ALLDONE
+There were no actual requests given to the function.
+.TP
+.B EAI_INTR
+A signal has interrupted the function.
+Note that this interruption might have been
+caused by signal notification of some completed look-up request.
+.P
+The
+.BR gai_error ()
+function can return
+.B EAI_INPROGRESS
+for an unfinished look-up request,
+0 for a successfully completed look-up
+(as described above), one of the error codes that could be returned by
+.BR getaddrinfo (3),
+or the error code
+.B EAI_CANCELED
+if the request has been canceled explicitly before it could be finished.
+.P
+The
+.BR gai_cancel ()
+function can return one of these values:
+.TP
+.B EAI_CANCELED
+The request has been canceled successfully.
+.TP
+.B EAI_NOTCANCELED
+The request has not been canceled.
+.TP
+.B EAI_ALLDONE
+The request has already completed.
+.P
+The
+.BR gai_strerror (3)
+function translates these error codes to a human readable string,
+suitable for error reporting.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getaddrinfo_a (),
+.BR gai_suspend (),
+.BR gai_error (),
+.BR gai_cancel ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.2.3.
+.P
+The interface of
+.BR getaddrinfo_a ()
+was modeled after the
+.BR lio_listio (3)
+interface.
+.SH EXAMPLES
+Two examples are provided: a simple example that resolves
+several requests in parallel synchronously, and a complex example
+showing some of the asynchronous capabilities.
+.SS Synchronous example
+The program below simply resolves several hostnames in parallel,
+giving a speed-up compared to resolving the hostnames sequentially using
+.BR getaddrinfo (3).
+The program might be used like this:
+.P
+.in +4n
+.EX
+$ \fB./a.out mirrors.kernel.org enoent.linuxfoundation.org gnu.org\fP
+mirrors.kernel.org: 139.178.88.99
+enoent.linuxfoundation.org: Name or service not known
+gnu.org: 209.51.188.116
+.EE
+.in
+.P
+Here is the program source code
+.P
+.\" SRC BEGIN (sync.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define MALLOC(n, type)  ((type *) reallocarray(NULL, n, sizeof(type)))
+\&
+int
+main(int argc, char *argv[])
+{
+    int ret;
+    struct gaicb *reqs[argc \- 1];
+    char host[NI_MAXHOST];
+    struct addrinfo *res;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s HOST...\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (size_t i = 0; i < argc \- 1; i++) {
+        reqs[i] = MALLOC(1, struct gaicb);
+        if (reqs[i] == NULL)
+            err(EXIT_FAILURE, "malloc");
+\&
+        memset(reqs[i], 0, sizeof(*reqs[0]));
+        reqs[i]\->ar_name = argv[i + 1];
+    }
+\&
+    ret = getaddrinfo_a(GAI_WAIT, reqs, argc \- 1, NULL);
+    if (ret != 0) {
+        fprintf(stderr, "getaddrinfo_a() failed: %s\en",
+                gai_strerror(ret));
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (size_t i = 0; i < argc \- 1; i++) {
+        printf("%s: ", reqs[i]\->ar_name);
+        ret = gai_error(reqs[i]);
+        if (ret == 0) {
+            res = reqs[i]\->ar_result;
+\&
+            ret = getnameinfo(res\->ai_addr, res\->ai_addrlen,
+                              host, sizeof(host),
+                              NULL, 0, NI_NUMERICHOST);
+            if (ret != 0) {
+                fprintf(stderr, "getnameinfo() failed: %s\en",
+                        gai_strerror(ret));
+                exit(EXIT_FAILURE);
+            }
+            puts(host);
+\&
+        } else {
+            puts(gai_strerror(ret));
+        }
+    }
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SS Asynchronous example
+This example shows a simple interactive
+.BR getaddrinfo_a ()
+front-end.
+The notification facility is not demonstrated.
+.P
+An example session might look like this:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+> a mirrors.kernel.org enoent.linuxfoundation.org gnu.org
+> c 2
+[2] gnu.org: Request not canceled
+> w 0 1
+[00] mirrors.kernel.org: Finished
+> l
+[00] mirrors.kernel.org: 139.178.88.99
+[01] enoent.linuxfoundation.org: Processing request in progress
+[02] gnu.org: 209.51.188.116
+> l
+[00] mirrors.kernel.org: 139.178.88.99
+[01] enoent.linuxfoundation.org: Name or service not known
+[02] gnu.org: 209.51.188.116
+.EE
+.in
+.P
+The program source is as follows:
+.P
+.\" SRC BEGIN (async.c)
+.EX
+#define _GNU_SOURCE
+#include <assert.h>
+#include <err.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define CALLOC(n, type)  ((type *) calloc(n, sizeof(type)))
+\&
+#define REALLOCF(ptr, n, type)                                          \e
+({                                                                      \e
+    static_assert(__builtin_types_compatible_p(typeof(ptr), type *));   \e
+                                                                        \e
+    (type *) reallocarrayf(ptr, n, sizeof(type));                       \e
+})
+\&
+static struct gaicb **reqs = NULL;
+static size_t nreqs = 0;
+\&
+static inline void *
+reallocarrayf(void *p, size_t nmemb, size_t size)
+{
+    void  *q;
+\&
+    q = reallocarray(p, nmemb, size);
+    if (q == NULL && nmemb != 0 && size != 0)
+        free(p);
+    return q;
+}
+\&
+static char *
+getcmd(void)
+{
+    static char buf[256];
+\&
+    fputs("> ", stdout); fflush(stdout);
+    if (fgets(buf, sizeof(buf), stdin) == NULL)
+        return NULL;
+\&
+    if (buf[strlen(buf) \- 1] == \[aq]\en\[aq])
+        buf[strlen(buf) \- 1] = 0;
+\&
+    return buf;
+}
+\&
+/* Add requests for specified hostnames. */
+static void
+add_requests(void)
+{
+    size_t nreqs_base = nreqs;
+    char *host;
+    int ret;
+\&
+    while ((host = strtok(NULL, " "))) {
+        nreqs++;
+        reqs = REALLOCF(reqs, nreqs, struct gaicb *);
+        if (reqs == NULL)
+            err(EXIT_FAILURE, "reallocf");
+\&
+        reqs[nreqs \- 1] = CALLOC(1, struct gaicb);
+        if (reqs[nreqs \- 1] == NULL)
+            err(EXIT_FAILURE, "calloc");
+\&
+        reqs[nreqs \- 1]\->ar_name = strdup(host);
+    }
+\&
+    /* Queue nreqs_base..nreqs requests. */
+\&
+    ret = getaddrinfo_a(GAI_NOWAIT, &reqs[nreqs_base],
+                        nreqs \- nreqs_base, NULL);
+    if (ret) {
+        fprintf(stderr, "getaddrinfo_a() failed: %s\en",
+                gai_strerror(ret));
+        exit(EXIT_FAILURE);
+    }
+}
+\&
+/* Wait until at least one of specified requests completes. */
+static void
+wait_requests(void)
+{
+    char *id;
+    int ret;
+    size_t n;
+    struct gaicb const **wait_reqs;
+\&
+    wait_reqs = CALLOC(nreqs, const struct gaicb *);
+    if (wait_reqs == NULL)
+        err(EXIT_FAILURE, "calloc");
+\&
+                /* NULL elements are ignored by gai_suspend(). */
+\&
+    while ((id = strtok(NULL, " ")) != NULL) {
+        n = atoi(id);
+\&
+        if (n >= nreqs) {
+            printf("Bad request number: %s\en", id);
+            return;
+        }
+\&
+        wait_reqs[n] = reqs[n];
+    }
+\&
+    ret = gai_suspend(wait_reqs, nreqs, NULL);
+    if (ret) {
+        printf("gai_suspend(): %s\en", gai_strerror(ret));
+        return;
+    }
+\&
+    for (size_t i = 0; i < nreqs; i++) {
+        if (wait_reqs[i] == NULL)
+            continue;
+\&
+        ret = gai_error(reqs[i]);
+        if (ret == EAI_INPROGRESS)
+            continue;
+\&
+        printf("[%02zu] %s: %s\en", i, reqs[i]\->ar_name,
+               ret == 0 ? "Finished" : gai_strerror(ret));
+    }
+}
+\&
+/* Cancel specified requests. */
+static void
+cancel_requests(void)
+{
+    char *id;
+    int ret;
+    size_t n;
+\&
+    while ((id = strtok(NULL, " ")) != NULL) {
+        n = atoi(id);
+\&
+        if (n >= nreqs) {
+            printf("Bad request number: %s\en", id);
+            return;
+        }
+\&
+        ret = gai_cancel(reqs[n]);
+        printf("[%s] %s: %s\en", id, reqs[atoi(id)]\->ar_name,
+               gai_strerror(ret));
+    }
+}
+\&
+/* List all requests. */
+static void
+list_requests(void)
+{
+    int ret;
+    char host[NI_MAXHOST];
+    struct addrinfo *res;
+\&
+    for (size_t i = 0; i < nreqs; i++) {
+        printf("[%02zu] %s: ", i, reqs[i]\->ar_name);
+        ret = gai_error(reqs[i]);
+\&
+        if (!ret) {
+            res = reqs[i]\->ar_result;
+\&
+            ret = getnameinfo(res\->ai_addr, res\->ai_addrlen,
+                              host, sizeof(host),
+                              NULL, 0, NI_NUMERICHOST);
+            if (ret) {
+                fprintf(stderr, "getnameinfo() failed: %s\en",
+                        gai_strerror(ret));
+                exit(EXIT_FAILURE);
+            }
+            puts(host);
+        } else {
+            puts(gai_strerror(ret));
+        }
+    }
+}
+\&
+int
+main(void)
+{
+    char *cmdline;
+    char *cmd;
+\&
+    while ((cmdline = getcmd()) != NULL) {
+        cmd = strtok(cmdline, " ");
+\&
+        if (cmd == NULL) {
+            list_requests();
+        } else {
+            switch (cmd[0]) {
+            case \[aq]a\[aq]:
+                add_requests();
+                break;
+            case \[aq]w\[aq]:
+                wait_requests();
+                break;
+            case \[aq]c\[aq]:
+                cancel_requests();
+                break;
+            case \[aq]l\[aq]:
+                list_requests();
+                break;
+            default:
+                fprintf(stderr, "Bad command: %c\en", cmd[0]);
+                break;
+            }
+        }
+    }
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getaddrinfo (3),
+.BR inet (3),
+.BR lio_listio (3),
+.BR hostname (7),
+.BR ip (7),
+.BR sigevent (3type)
diff --git a/man/man3/getaliasbyname.3 b/man/man3/getaliasbyname.3
new file mode 100644
index 000000000..37dcf1914
--- /dev/null
+++ b/man/man3/getaliasbyname.3
@@ -0,0 +1 @@
+.so man3/setaliasent.3
diff --git a/man/man3/getaliasbyname_r.3 b/man/man3/getaliasbyname_r.3
new file mode 100644
index 000000000..37dcf1914
--- /dev/null
+++ b/man/man3/getaliasbyname_r.3
@@ -0,0 +1 @@
+.so man3/setaliasent.3
diff --git a/man/man3/getaliasent.3 b/man/man3/getaliasent.3
new file mode 100644
index 000000000..37dcf1914
--- /dev/null
+++ b/man/man3/getaliasent.3
@@ -0,0 +1 @@
+.so man3/setaliasent.3
diff --git a/man/man3/getaliasent_r.3 b/man/man3/getaliasent_r.3
new file mode 100644
index 000000000..37dcf1914
--- /dev/null
+++ b/man/man3/getaliasent_r.3
@@ -0,0 +1 @@
+.so man3/setaliasent.3
diff --git a/man/man3/getauxval.3 b/man/man3/getauxval.3
new file mode 100644
index 000000000..082d9586a
--- /dev/null
+++ b/man/man3/getauxval.3
@@ -0,0 +1,272 @@
+'\" t
+.\" Copyright 2012 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" See also https://lwn.net/Articles/519085/
+.\"
+.TH getauxval 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getauxval \- retrieve a value from the auxiliary vector
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/auxv.h>
+.P
+.BI "unsigned long getauxval(unsigned long " type );
+.fi
+.SH DESCRIPTION
+The
+.BR getauxval ()
+function retrieves values from the auxiliary vector,
+a mechanism that the kernel's ELF binary loader
+uses to pass certain information to
+user space when a program is executed.
+.P
+Each entry in the auxiliary vector consists of a pair of values:
+a type that identifies what this entry represents,
+and a value for that type.
+Given the argument
+.IR type ,
+.BR getauxval ()
+returns the corresponding value.
+.P
+The value returned for each
+.I type
+is given in the following list.
+Not all
+.I type
+values are present on all architectures.
+.TP
+.B AT_BASE
+The base address of the program interpreter (usually, the dynamic linker).
+.TP
+.B AT_BASE_PLATFORM
+A pointer to a string (PowerPC and MIPS only).
+On PowerPC, this identifies the real platform; may differ from
+.BR AT_PLATFORM "."
+On MIPS,
+.\" commit e585b768da111f2c2d413de6214e83bbdfee8f22
+this identifies the ISA level (since Linux 5.7).
+.TP
+.B AT_CLKTCK
+The frequency with which
+.BR times (2)
+counts.
+This value can also be obtained via
+.IR sysconf(_SC_CLK_TCK) .
+.TP
+.B AT_DCACHEBSIZE
+The data cache block size.
+.TP
+.B AT_EGID
+The effective group ID of the thread.
+.TP
+.B AT_ENTRY
+The entry address of the executable.
+.TP
+.B AT_EUID
+The effective user ID of the thread.
+.TP
+.B AT_EXECFD
+File descriptor of program.
+.TP
+.B AT_EXECFN
+A pointer to a string containing the pathname used to execute the program.
+.TP
+.B AT_FLAGS
+Flags (unused).
+.TP
+.B AT_FPUCW
+Used FPU control word (SuperH architecture only).
+This gives some information about the FPU initialization
+performed by the kernel.
+.TP
+.B AT_GID
+The real group ID of the thread.
+.TP
+.B AT_HWCAP
+An architecture and ABI dependent bit-mask whose settings
+indicate detailed processor capabilities.
+The contents of the bit mask are hardware dependent
+(for example, see the kernel source file
+.I arch/x86/include/asm/cpufeature.h
+for details relating to the Intel x86 architecture; the value
+returned is the first 32-bit word of the array described there).
+A human-readable version of the same information is available via
+.IR /proc/cpuinfo .
+.TP
+.BR AT_HWCAP2 " (since glibc 2.18)"
+Further machine-dependent hints about processor capabilities.
+.TP
+.B AT_ICACHEBSIZE
+The instruction cache block size.
+.\" .TP
+.\" .BR AT_IGNORE
+.\" .TP
+.\" .BR AT_IGNOREPPC
+.\" .TP
+.\" .BR AT_NOTELF
+.TP
+.\" Kernel commit 98a5f361b8625c6f4841d6ba013bbf0e80d08147
+.B AT_L1D_CACHEGEOMETRY
+Geometry of the L1 data cache, encoded with the cache line size in bytes
+in the bottom 16 bits and the cache associativity in the next 16 bits.
+The associativity is such that if N is the 16-bit value,
+the cache is N-way set associative.
+.TP
+.B AT_L1D_CACHESIZE
+The L1 data cache size.
+.TP
+.B AT_L1I_CACHEGEOMETRY
+Geometry of the L1 instruction cache, encoded as for
+.BR AT_L1D_CACHEGEOMETRY .
+.TP
+.B AT_L1I_CACHESIZE
+The L1 instruction cache size.
+.TP
+.B AT_L2_CACHEGEOMETRY
+Geometry of the L2 cache, encoded as for
+.BR AT_L1D_CACHEGEOMETRY .
+.TP
+.B AT_L2_CACHESIZE
+The L2 cache size.
+.TP
+.B AT_L3_CACHEGEOMETRY
+Geometry of the L3 cache, encoded as for
+.BR AT_L1D_CACHEGEOMETRY .
+.TP
+.B AT_L3_CACHESIZE
+The L3 cache size.
+.TP
+.B AT_PAGESZ
+The system page size (the same value returned by
+.IR sysconf(_SC_PAGESIZE) ).
+.TP
+.B AT_PHDR
+The address of the program headers of the executable.
+.TP
+.B AT_PHENT
+The size of program header entry.
+.TP
+.B AT_PHNUM
+The number of program headers.
+.TP
+.B AT_PLATFORM
+A pointer to a string that identifies the hardware platform
+that the program is running on.
+The dynamic linker uses this in the interpretation of
+.I rpath
+values.
+.TP
+.B AT_RANDOM
+The address of sixteen bytes containing a random value.
+.TP
+.B AT_SECURE
+Has a nonzero value if this executable should be treated securely.
+Most commonly, a nonzero value indicates that the process is
+executing a set-user-ID or set-group-ID binary
+(so that its real and effective UIDs or GIDs differ from one another),
+or that it gained capabilities by executing
+a binary file that has capabilities (see
+.BR capabilities (7)).
+Alternatively,
+a nonzero value may be triggered by a Linux Security Module.
+When this value is nonzero,
+the dynamic linker disables the use of certain environment variables (see
+.BR ld\-linux.so (8))
+and glibc changes other aspects of its behavior.
+(See also
+.BR secure_getenv (3).)
+.TP
+.B AT_SYSINFO
+The entry point to the system call function in the vDSO.
+Not present/needed on all architectures (e.g., absent on x86-64).
+.TP
+.B AT_SYSINFO_EHDR
+The address of a page containing the virtual Dynamic Shared Object (vDSO)
+that the kernel creates in order to provide fast implementations of
+certain system calls.
+.TP
+.B AT_UCACHEBSIZE
+The unified cache block size.
+.TP
+.B AT_UID
+The real user ID of the thread.
+.SH RETURN VALUE
+On success,
+.BR getauxval ()
+returns the value corresponding to
+.IR type .
+If
+.I type
+is not found, 0 is returned.
+.SH ERRORS
+.TP
+.BR ENOENT " (since glibc 2.19)"
+.\" commit b9ab448f980e296eac21ac65f53783967cc6037b
+No entry corresponding to
+.I type
+could be found in the auxiliary vector.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getauxval ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.16.
+.SH NOTES
+The primary consumer of the information in the auxiliary vector
+is the dynamic linker,
+.BR ld\-linux.so (8).
+The auxiliary vector is a convenient and efficient shortcut
+that allows the kernel to communicate a certain set of standard
+information that the dynamic linker usually or always needs.
+In some cases, the same information could be obtained by system calls,
+but using the auxiliary vector is cheaper.
+.P
+The auxiliary vector resides just above the argument list and
+environment in the process address space.
+The auxiliary vector supplied to a program can be viewed by setting the
+.B LD_SHOW_AUXV
+environment variable when running a program:
+.P
+.in +4n
+.EX
+$ LD_SHOW_AUXV=1 sleep 1
+.EE
+.in
+.P
+The auxiliary vector of any process can (subject to file permissions)
+be obtained via
+.IR /proc/ pid /auxv ;
+see
+.BR proc (5)
+for more information.
+.SH BUGS
+Before the addition of the
+.B ENOENT
+error in glibc 2.19,
+there was no way to unambiguously distinguish the case where
+.I type
+could not be found from the case where the value corresponding to
+.I type
+was zero.
+.SH SEE ALSO
+.BR execve (2),
+.BR secure_getenv (3),
+.BR vdso (7),
+.BR ld\-linux.so (8)
diff --git a/man/man3/getc.3 b/man/man3/getc.3
new file mode 100644
index 000000000..2f6585a10
--- /dev/null
+++ b/man/man3/getc.3
@@ -0,0 +1 @@
+.so man3/fgetc.3
diff --git a/man/man3/getc_unlocked.3 b/man/man3/getc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/getc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/getchar.3 b/man/man3/getchar.3
new file mode 100644
index 000000000..2f6585a10
--- /dev/null
+++ b/man/man3/getchar.3
@@ -0,0 +1 @@
+.so man3/fgetc.3
diff --git a/man/man3/getchar_unlocked.3 b/man/man3/getchar_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/getchar_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/getcontext.3 b/man/man3/getcontext.3
new file mode 100644
index 000000000..ef2f35fff
--- /dev/null
+++ b/man/man3/getcontext.3
@@ -0,0 +1,201 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getcontext 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getcontext, setcontext \- get or set the user context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <ucontext.h>
+.P
+.BI "int getcontext(ucontext_t *" ucp );
+.BI "int setcontext(const ucontext_t *" ucp );
+.fi
+.SH DESCRIPTION
+In a System V-like environment, one has the two types
+.I mcontext_t
+and
+.I ucontext_t
+defined in
+.I <ucontext.h>
+and the four functions
+.BR getcontext (),
+.BR setcontext (),
+.BR makecontext (3),
+and
+.BR swapcontext (3)
+that allow user-level context switching between multiple
+threads of control within a process.
+.P
+The
+.I mcontext_t
+type is machine-dependent and opaque.
+The
+.I ucontext_t
+type is a structure that has at least
+the following fields:
+.P
+.in +4n
+.EX
+typedef struct ucontext_t {
+    struct ucontext_t *uc_link;
+    sigset_t          uc_sigmask;
+    stack_t           uc_stack;
+    mcontext_t        uc_mcontext;
+    ...
+} ucontext_t;
+.EE
+.in
+.P
+with
+.I sigset_t
+and
+.I stack_t
+defined in
+.IR <signal.h> .
+Here
+.I uc_link
+points to the context that will be resumed
+when the current context terminates (in case the current context
+was created using
+.BR makecontext (3)),
+.I uc_sigmask
+is the
+set of signals blocked in this context (see
+.BR sigprocmask (2)),
+.I uc_stack
+is the stack used by this context (see
+.BR sigaltstack (2)),
+and
+.I uc_mcontext
+is the
+machine-specific representation of the saved context,
+that includes the calling thread's machine registers.
+.P
+The function
+.BR getcontext ()
+initializes the structure
+pointed to by
+.I ucp
+to the currently active context.
+.P
+The function
+.BR setcontext ()
+restores the user context
+pointed to by
+.IR ucp .
+A successful call does not return.
+The context should have been obtained by a call of
+.BR getcontext (),
+or
+.BR makecontext (3),
+or received as the third argument to a signal
+handler (see the discussion of the
+.B SA_SIGINFO
+flag in
+.BR sigaction (2)).
+.P
+If the context was obtained by a call of
+.BR getcontext (),
+program execution continues as if this call just returned.
+.P
+If the context was obtained by a call of
+.BR makecontext (3),
+program execution continues by a call to the function
+.I func
+specified as the second argument of that call to
+.BR makecontext (3).
+When the function
+.I func
+returns, we continue with the
+.I uc_link
+member of the structure
+.I ucp
+specified as the
+first argument of that call to
+.BR makecontext (3).
+When this member is NULL, the thread exits.
+.P
+If the context was obtained by a call to a signal handler,
+then old standard text says that "program execution continues with the
+program instruction following the instruction interrupted
+by the signal".
+However, this sentence was removed in SUSv2,
+and the present verdict is "the result is unspecified".
+.SH RETURN VALUE
+When successful,
+.BR getcontext ()
+returns 0 and
+.BR setcontext ()
+does not return.
+On error, both return \-1 and set
+.I errno
+to indicate the error.
+.SH ERRORS
+None defined.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getcontext (),
+.BR setcontext ()
+T}	Thread safety	MT-Safe race:ucp
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SUSv2, POSIX.1-2001.
+.P
+POSIX.1-2008 removes these functions,
+citing portability issues, and
+recommending that applications be rewritten to use POSIX threads instead.
+.SH NOTES
+The earliest incarnation of this mechanism was the
+.BR setjmp (3)/\c
+.BR longjmp (3)
+mechanism.
+Since that does not define
+the handling of the signal context, the next stage was the
+.BR sigsetjmp (3)/\c
+.BR siglongjmp (3)
+pair.
+The present mechanism gives much more control.
+On the other hand,
+there is no easy way to detect whether a return from
+.BR getcontext ()
+is from the first call, or via a
+.BR setcontext ()
+call.
+The user has to invent their own bookkeeping device, and a register
+variable won't do since registers are restored.
+.P
+When a signal occurs, the current user context is saved and
+a new context is created by the kernel for the signal handler.
+Do not leave the handler using
+.BR longjmp (3):
+it is undefined what would happen with contexts.
+Use
+.BR siglongjmp (3)
+or
+.BR setcontext ()
+instead.
+.SH SEE ALSO
+.BR sigaction (2),
+.BR sigaltstack (2),
+.BR sigprocmask (2),
+.BR longjmp (3),
+.BR makecontext (3),
+.BR sigsetjmp (3),
+.BR signal (7)
diff --git a/man/man3/getcwd.3 b/man/man3/getcwd.3
new file mode 100644
index 000000000..6ba1e3280
--- /dev/null
+++ b/man/man3/getcwd.3
@@ -0,0 +1,311 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 21 22:35:42 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 18 Mar 1996 by Martin Schulze (joey@infodrom.north.de):
+.\"   Corrected description of getwd().
+.\" Modified Sat Aug 21 12:32:12 MET 1999 by aeb - applied fix by aj
+.\" Modified Mon Dec 11 13:32:51 MET 2000 by aeb
+.\" Modified Thu Apr 22 03:49:15 CEST 2002 by Roger Luethi <rl@hellgate.ch>
+.\"
+.TH getcwd 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getcwd, getwd, get_current_dir_name \- get current working directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "char *getcwd(char " buf [. size "], size_t " size );
+.B "char *get_current_dir_name(void);"
+.P
+.BI "[[deprecated]] char *getwd(char " buf [PATH_MAX]);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR get_current_dir_name ():
+.nf
+    _GNU_SOURCE
+.fi
+.P
+.BR getwd ():
+.nf
+    Since glibc 2.12:
+        (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE
+    Before glibc 2.12:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+These functions return a null-terminated string containing an
+absolute pathname that is the current working directory of
+the calling process.
+The pathname is returned as the function result and via the argument
+.IR buf ,
+if present.
+.P
+The
+.BR getcwd ()
+function copies an absolute pathname of the current working directory
+to the array pointed to by
+.IR buf ,
+which is of length
+.IR size .
+.P
+If the length of the absolute pathname of the current working directory,
+including the terminating null byte, exceeds
+.I size
+bytes, NULL is returned, and
+.I errno
+is set to
+.BR ERANGE ;
+an application should check for this error, and allocate a larger
+buffer if necessary.
+.P
+As an extension to the POSIX.1-2001 standard, glibc's
+.BR getcwd ()
+allocates the buffer dynamically using
+.BR malloc (3)
+if
+.I buf
+is NULL.
+In this case, the allocated buffer has the length
+.I size
+unless
+.I size
+is zero, when
+.I buf
+is allocated as big as necessary.
+The caller should
+.BR free (3)
+the returned buffer.
+.P
+.BR get_current_dir_name ()
+will
+.BR malloc (3)
+an array big enough to hold the absolute pathname of
+the current working directory.
+If the environment
+variable
+.B PWD
+is set, and its value is correct, then that value will be returned.
+The caller should
+.BR free (3)
+the returned buffer.
+.P
+.BR getwd ()
+does not
+.BR malloc (3)
+any memory.
+The
+.I buf
+argument should be a pointer to an array at least
+.B PATH_MAX
+bytes long.
+If the length of the absolute pathname of the current working directory,
+including the terminating null byte, exceeds
+.B PATH_MAX
+bytes, NULL is returned, and
+.I errno
+is set to
+.BR ENAMETOOLONG .
+(Note that on some systems,
+.B PATH_MAX
+may not be a compile-time constant;
+furthermore, its value may depend on the filesystem, see
+.BR pathconf (3).)
+For portability and security reasons, use of
+.BR getwd ()
+is deprecated.
+.SH RETURN VALUE
+On success, these functions return a pointer to a string containing
+the pathname of the current working directory.
+In the case of
+.BR getcwd ()
+and
+.BR getwd ()
+this is the same value as
+.IR buf .
+.P
+On failure, these functions return NULL, and
+.I errno
+is set to indicate the error.
+The contents of the array pointed to by
+.I buf
+are undefined on error.
+.SH ERRORS
+.TP
+.B EACCES
+Permission to read or search a component of the filename was denied.
+.TP
+.B EFAULT
+.I buf
+points to a bad address.
+.TP
+.B EINVAL
+The
+.I size
+argument is zero and
+.I buf
+is not a null pointer.
+.TP
+.B EINVAL
+.BR getwd ():
+.I buf
+is NULL.
+.TP
+.B ENAMETOOLONG
+.BR getwd ():
+The size of the null-terminated absolute pathname string exceeds
+.B PATH_MAX
+bytes.
+.TP
+.B ENOENT
+The current working directory has been unlinked.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ERANGE
+The
+.I size
+argument is less than the length of the absolute pathname of the
+working directory, including the terminating null byte.
+You need to allocate a bigger array and try again.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getcwd (),
+.BR getwd ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR get_current_dir_name ()
+T}	Thread safety	MT-Safe env
+.TE
+.SH VERSIONS
+POSIX.1-2001 leaves the behavior of
+.BR getcwd ()
+unspecified if
+.I buf
+is NULL.
+.P
+POSIX.1-2001
+does not define any errors for
+.BR getwd ().
+.SH VERSIONS
+.SS C library/kernel differences
+On Linux, the kernel provides a
+.BR getcwd ()
+system call, which the functions described in this page will use if possible.
+The system call takes the same arguments as the library function
+of the same name, but is limited to returning at most
+.B PATH_MAX
+bytes.
+(Before Linux 3.12,
+.\" commit 3272c544da48f8915a0e34189182aed029bd0f2b
+the limit on the size of the returned pathname was the system page size.
+On many architectures,
+.B PATH_MAX
+and the system page size are both 4096 bytes,
+but a few architectures have a larger page size.)
+If the length of the pathname of the current working directory
+exceeds this limit, then the system call fails with the error
+.BR ENAMETOOLONG .
+In this case, the library functions fall back to
+a (slower) alternative implementation that returns the full pathname.
+.P
+Following a change in Linux 2.6.36,
+.\" commit 8df9d1a4142311c084ffeeacb67cd34d190eff74
+the pathname returned by the
+.BR getcwd ()
+system call will be prefixed with the string "(unreachable)"
+if the current directory is not below the root directory of the current
+process (e.g., because the process set a new filesystem root using
+.BR chroot (2)
+without changing its current directory into the new root).
+Such behavior can also be caused by an unprivileged user by changing
+the current directory into another mount namespace.
+When dealing with pathname from untrusted sources, callers of the
+functions described in this page
+should consider checking whether the returned pathname starts
+with '/' or '(' to avoid misinterpreting an unreachable path
+as a relative pathname.
+.SH STANDARDS
+.TP
+.BR getcwd ()
+POSIX.1-2008.
+.TP
+.BR get_current_dir_name ()
+GNU.
+.TP
+.BR getwd ()
+None.
+.SH HISTORY
+.TP
+.BR getcwd ()
+POSIX.1-2001.
+.TP
+.BR getwd ()
+POSIX.1-2001, but marked LEGACY.
+Removed in POSIX.1-2008.
+Use
+.BR getcwd ()
+instead.
+.P
+Under Linux, these functions make use of the
+.BR getcwd ()
+system call (available since Linux 2.1.92).
+On older systems they would query
+.IR /proc/self/cwd .
+If both system call and proc filesystem are missing, a
+generic implementation is called.
+Only in that case can
+these calls fail under Linux with
+.BR EACCES .
+.SH NOTES
+These functions are often used to save the location of the current working
+directory for the purpose of returning to it later.
+Opening the current
+directory (".") and calling
+.BR fchdir (2)
+to return is usually a faster and more reliable alternative when sufficiently
+many file descriptors are available, especially on platforms other than Linux.
+.SH BUGS
+Since the Linux 2.6.36 change that added "(unreachable)" in the
+circumstances described above, the glibc implementation of
+.BR getcwd ()
+has failed to conform to POSIX and returned a relative pathname when the API
+contract requires an absolute pathname.
+With glibc 2.27 onwards this is corrected;
+calling
+.BR getcwd ()
+from such a pathname will now result in failure with
+.BR ENOENT .
+.SH SEE ALSO
+.BR pwd (1),
+.BR chdir (2),
+.BR fchdir (2),
+.BR open (2),
+.BR unlink (2),
+.BR free (3),
+.BR malloc (3)
diff --git a/man/man3/getdate.3 b/man/man3/getdate.3
new file mode 100644
index 000000000..74e4a086e
--- /dev/null
+++ b/man/man3/getdate.3
@@ -0,0 +1,322 @@
+'\" t
+.\" Copyright 2001 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified, 2001-12-26, aeb
+.\" 2008-09-07, mtk, Various rewrites; added an example program.
+.\"
+.TH getdate 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getdate, getdate_r \- convert a date-plus-time string to broken-down time
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <time.h>"
+.P
+.BI "struct tm *getdate(const char *" string );
+.P
+.B "extern int getdate_err;"
+.P
+.BI "int getdate_r(const char *restrict " string ", struct tm *restrict " res );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getdate ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.P
+.BR getdate_r ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The function
+.BR getdate ()
+converts a string representation of a date and time,
+contained in the buffer pointed to by
+.IR string ,
+into a broken-down time.
+The broken-down time is stored in a
+.I tm
+structure, and a pointer to this
+structure is returned as the function result.
+This
+.I tm
+structure is allocated in static storage,
+and consequently it will be overwritten by further calls to
+.BR getdate ().
+.P
+In contrast to
+.BR strptime (3),
+(which has a
+.I format
+argument),
+.BR getdate ()
+uses the formats found in the file
+whose full pathname is given in the environment variable
+.BR DATEMSK .
+The first line in the file that matches the given input string
+is used for the conversion.
+.P
+The matching is done case insensitively.
+Superfluous whitespace, either in the pattern or in the string to
+be converted, is ignored.
+.P
+The conversion specifications that a pattern can contain are those given for
+.BR strptime (3).
+One more conversion specification is specified in POSIX.1-2001:
+.TP
+.B %Z
+Timezone name.
+.\" FIXME Is it (still) true that %Z is not supported in glibc?
+.\" Looking at the glibc 2.21 source code, where the implementation uses
+.\" strptime(), suggests that it might be supported.
+This is not implemented in glibc.
+.P
+When
+.B %Z
+is given, the structure containing the broken-down time
+is initialized with values corresponding to the current
+time in the given timezone.
+Otherwise, the structure is initialized to the broken-down time
+corresponding to the current local time (as by a call to
+.BR localtime (3)).
+.P
+When only the day of the week is given,
+the day is taken to be the first such day
+on or after today.
+.P
+When only the month is given (and no year), the month is taken to
+be the first such month equal to or after the current month.
+If no day is given, it is the first day of the month.
+.P
+When no hour, minute, and second are given, the current
+hour, minute, and second are taken.
+.P
+If no date is given, but we know the hour, then that hour is taken
+to be the first such hour equal to or after the current hour.
+.P
+.BR getdate_r ()
+is a GNU extension that provides a reentrant version of
+.BR getdate ().
+Rather than using a global variable to report errors and a static buffer
+to return the broken down time,
+it returns errors via the function result value,
+and returns the resulting broken-down time in the
+caller-allocated buffer pointed to by the argument
+.IR res .
+.SH RETURN VALUE
+When successful,
+.BR getdate ()
+returns a pointer to a
+.IR "struct tm" .
+Otherwise, it returns NULL and sets the global variable
+.I getdate_err
+to one of the error numbers shown below.
+Changes to
+.I errno
+are unspecified.
+.P
+On success
+.BR getdate_r ()
+returns 0;
+on error it returns one of the error numbers shown below.
+.SH ERRORS
+The following errors are returned via
+.I getdate_err
+(for
+.BR getdate ())
+or as the function result (for
+.BR getdate_r ()):
+.TP 4n
+.B 1
+The
+.B DATEMSK
+environment variable is not defined, or its value is an empty string.
+.TP
+.B 2
+The template file specified by
+.B DATEMSK
+cannot be opened for reading.
+.TP
+.B 3
+Failed to get file status information.
+.\" stat()
+.TP
+.B 4
+The template file is not a regular file.
+.TP
+.B 5
+An error was encountered while reading the template file.
+.TP
+.B 6
+Memory allocation failed (not enough memory available).
+.\" Error 6 doesn't seem to occur in glibc
+.TP
+.B 7
+There is no line in the file that matches the input.
+.TP
+.B 8
+Invalid input specification.
+.SH ENVIRONMENT
+.TP
+.B DATEMSK
+File containing format patterns.
+.TP
+.B TZ
+.TQ
+.B LC_TIME
+Variables used by
+.BR strptime (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getdate ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:getdate env locale
+T}
+T{
+.na
+.nh
+.BR getdate_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe env locale
+T}
+.TE
+.SH VERSIONS
+The POSIX.1 specification for
+.BR strptime (3)
+contains conversion specifications using the
+.B %E
+or
+.B %O
+modifier, while such specifications are not given for
+.BR getdate ().
+In glibc,
+.BR getdate ()
+is implemented using
+.BR strptime (3),
+so that precisely the same conversions are supported by both.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+The program below calls
+.BR getdate ()
+for each of its command-line arguments,
+and for each call displays the values in the fields of the returned
+.I tm
+structure.
+The following shell session demonstrates the operation of the program:
+.P
+.in +4n
+.EX
+.RB "$" " TFILE=$PWD/tfile"
+.RB "$" " echo \[aq]%A\[aq] > $TFILE " "      # Full name of the day of the week"
+.RB "$" " echo \[aq]%T\[aq] >> $TFILE" "      # Time (HH:MM:SS)"
+.RB "$" " echo \[aq]%F\[aq] >> $TFILE" "      # ISO date (YYYY\-MM\-DD)"
+.RB "$" " date"
+.RB "$" " export DATEMSK=$TFILE"
+.RB "$" " ./a.out Tuesday \[aq]2009\-12\-28\[aq] \[aq]12:22:33\[aq]"
+Sun Sep  7 06:03:36 CEST 2008
+Call 1 ("Tuesday") succeeded:
+    tm_sec   = 36
+    tm_min   = 3
+    tm_hour  = 6
+    tm_mday  = 9
+    tm_mon   = 8
+    tm_year  = 108
+    tm_wday  = 2
+    tm_yday  = 252
+    tm_isdst = 1
+Call 2 ("2009\-12\-28") succeeded:
+    tm_sec   = 36
+    tm_min   = 3
+    tm_hour  = 6
+    tm_mday  = 28
+    tm_mon   = 11
+    tm_year  = 109
+    tm_wday  = 1
+    tm_yday  = 361
+    tm_isdst = 0
+Call 3 ("12:22:33") succeeded:
+    tm_sec   = 33
+    tm_min   = 22
+    tm_hour  = 12
+    tm_mday  = 7
+    tm_mon   = 8
+    tm_year  = 108
+    tm_wday  = 0
+    tm_yday  = 250
+    tm_isdst = 1
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (getdate.c)
+.EX
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    struct tm *tmp;
+\&
+    for (size_t j = 1; j < argc; j++) {
+        tmp = getdate(argv[j]);
+\&
+        if (tmp == NULL) {
+            printf("Call %zu failed; getdate_err = %d\en",
+                   j, getdate_err);
+            continue;
+        }
+\&
+        printf("Call %zu (\e"%s\e") succeeded:\en", j, argv[j]);
+        printf("    tm_sec   = %d\en", tmp\->tm_sec);
+        printf("    tm_min   = %d\en", tmp\->tm_min);
+        printf("    tm_hour  = %d\en", tmp\->tm_hour);
+        printf("    tm_mday  = %d\en", tmp\->tm_mday);
+        printf("    tm_mon   = %d\en", tmp\->tm_mon);
+        printf("    tm_year  = %d\en", tmp\->tm_year);
+        printf("    tm_wday  = %d\en", tmp\->tm_wday);
+        printf("    tm_yday  = %d\en", tmp\->tm_yday);
+        printf("    tm_isdst = %d\en", tmp\->tm_isdst);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR time (2),
+.BR localtime (3),
+.BR setlocale (3),
+.BR strftime (3),
+.BR strptime (3)
diff --git a/man/man3/getdate_err.3 b/man/man3/getdate_err.3
new file mode 100644
index 000000000..c78ed340c
--- /dev/null
+++ b/man/man3/getdate_err.3
@@ -0,0 +1 @@
+.so man3/getdate.3
diff --git a/man/man3/getdate_r.3 b/man/man3/getdate_r.3
new file mode 100644
index 000000000..c78ed340c
--- /dev/null
+++ b/man/man3/getdate_r.3
@@ -0,0 +1 @@
+.so man3/getdate.3
diff --git a/man/man3/getdelim.3 b/man/man3/getdelim.3
new file mode 100644
index 000000000..caf4e4894
--- /dev/null
+++ b/man/man3/getdelim.3
@@ -0,0 +1 @@
+.so man3/getline.3
diff --git a/man/man3/getdirentries.3 b/man/man3/getdirentries.3
new file mode 100644
index 000000000..b738192af
--- /dev/null
+++ b/man/man3/getdirentries.3
@@ -0,0 +1,80 @@
+'\" t
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\" Portions extracted from /usr/include/dirent.h are:
+.\"                    Copyright 1991, 1992 Free Software Foundation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getdirentries 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getdirentries \- get directory entries in a filesystem-independent format
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <dirent.h>
+.P
+.BI "ssize_t getdirentries(int " fd ", char " buf "[restrict ." nbytes "], \
+size_t " nbytes ,
+.BI "                      off_t *restrict " basep );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getdirentries ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+Read directory entries from the directory specified by
+.I fd
+into
+.IR buf .
+At most
+.I nbytes
+are read.
+Reading starts at offset
+.IR *basep ,
+and
+.I *basep
+is updated with the new position after reading.
+.SH RETURN VALUE
+.BR getdirentries ()
+returns the number of bytes read or zero when at the end of the directory.
+If an error occurs, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+See the Linux library source code for details.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getdirentries ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+BSD.
+.SH NOTES
+Use
+.BR opendir (3)
+and
+.BR readdir (3)
+instead.
+.SH SEE ALSO
+.BR lseek (2),
+.BR open (2)
diff --git a/man/man3/getdtablesize.3 b/man/man3/getdtablesize.3
new file mode 100644
index 000000000..9482886f7
--- /dev/null
+++ b/man/man3/getdtablesize.3
@@ -0,0 +1,88 @@
+'\" t
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 2002-04-15 by Roger Luethi <rl@hellgate.ch> and aeb
+.\"
+.TH getdtablesize 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getdtablesize \- get file descriptor table size
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B int getdtablesize(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getdtablesize ():
+.nf
+    Since glibc 2.20:
+        _DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
+    glibc 2.12 to glibc 2.19:
+        _BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
+    Before glibc 2.12:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+.BR getdtablesize ()
+returns the maximum number of files a process can have open,
+one more than the largest possible value for a file descriptor.
+.SH RETURN VALUE
+The current limit on the number of open files per process.
+.SH ERRORS
+On Linux,
+.BR getdtablesize ()
+can return any of the errors described for
+.BR getrlimit (2);
+see NOTES below.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getdtablesize ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The glibc version of
+.BR getdtablesize ()
+calls
+.BR getrlimit (2)
+and returns the current
+.B RLIMIT_NOFILE
+limit, or
+.B OPEN_MAX
+when that fails.
+.\" The libc4 and libc5 versions return
+.\" .B OPEN_MAX
+.\" (set to 256 since Linux 0.98.4).
+.P
+Portable applications should employ
+.I sysconf(_SC_OPEN_MAX)
+instead of this call.
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4, 4.4BSD
+(first appeared in 4.2BSD).
+.SH SEE ALSO
+.BR close (2),
+.BR dup (2),
+.BR getrlimit (2),
+.BR open (2)
diff --git a/man/man3/getentropy.3 b/man/man3/getentropy.3
new file mode 100644
index 000000000..a26a4eff5
--- /dev/null
+++ b/man/man3/getentropy.3
@@ -0,0 +1,103 @@
+.\" Copyright (C) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getentropy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getentropy \- fill a buffer with random bytes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int getentropy(void " buffer [. length "], size_t " length );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getentropy ():
+.nf
+    _DEFAULT_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getentropy ()
+function writes
+.I length
+bytes of high-quality random data to the buffer starting
+at the location pointed to by
+.IR buffer .
+The maximum permitted value for the
+.I length
+argument is 256.
+.P
+A successful call to
+.BR getentropy ()
+always provides the requested number of bytes of entropy.
+.SH RETURN VALUE
+On success, this function returns zero.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EFAULT
+Part or all of the buffer specified by
+.I buffer
+and
+.I length
+is not in valid addressable memory.
+.TP
+.B EIO
+.I length
+is greater than 256.
+.TP
+.B EIO
+An unspecified error occurred while trying to overwrite
+.I buffer
+with random data.
+.TP
+.B ENOSYS
+This kernel version does not implement the
+.BR getrandom (2)
+system call required to implement this function.
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.25.
+OpenBSD.
+.SH NOTES
+The
+.BR getentropy ()
+function is implemented using
+.BR getrandom (2).
+.P
+Whereas the glibc wrapper makes
+.BR getrandom (2)
+a cancelation point,
+.BR getentropy ()
+is not a cancelation point.
+.P
+.BR getentropy ()
+is also declared in
+.BR <sys/random.h> .
+(No feature test macro need be defined to obtain the declaration from
+that header file.)
+.P
+A call to
+.BR getentropy ()
+may block if the system has just booted and the kernel has
+not yet collected enough randomness to initialize the entropy pool.
+In this case,
+.BR getentropy ()
+will keep blocking even if a signal is handled,
+and will return only once the entropy pool has been initialized.
+.SH SEE ALSO
+.BR getrandom (2),
+.BR urandom (4),
+.BR random (7)
diff --git a/man/man3/getenv.3 b/man/man3/getenv.3
new file mode 100644
index 000000000..65bc3c81e
--- /dev/null
+++ b/man/man3/getenv.3
@@ -0,0 +1,141 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (C) 2007, 2012 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:30:29 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Feb 14 21:47:50 1997 by Andries Brouwer (aeb@cwi.nl)
+.\"
+.TH getenv 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getenv, secure_getenv \- get an environment variable
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "char *getenv(const char *" name );
+.BI "char *secure_getenv(const char *" name );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR secure_getenv ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getenv ()
+function searches the environment list to find the
+environment variable
+.IR name ,
+and returns a pointer to the corresponding
+.I value
+string.
+.P
+The GNU-specific
+.BR secure_getenv ()
+function is just like
+.BR getenv ()
+except that it returns NULL in cases where "secure execution" is required.
+Secure execution is required if one of the following conditions
+was true when the program run by the calling process was loaded:
+.IP \[bu] 3
+the process's effective user ID did not match its real user ID or
+the process's effective group ID did not match its real group ID
+(typically this is the result of executing a set-user-ID or
+set-group-ID program);
+.IP \[bu]
+the effective capability bit was set on the executable file; or
+.IP \[bu]
+the process has a nonempty permitted capability set.
+.P
+Secure execution may also be required if triggered
+by some Linux security modules.
+.P
+The
+.BR secure_getenv ()
+function is intended for use in general-purpose libraries
+to avoid vulnerabilities that could occur if
+set-user-ID or set-group-ID programs accidentally
+trusted the environment.
+.SH RETURN VALUE
+The
+.BR getenv ()
+function returns a pointer to the value in the
+environment, or NULL if there is no match.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getenv (),
+.BR secure_getenv ()
+T}	Thread safety	MT-Safe env
+.TE
+.SH STANDARDS
+.TP
+.BR getenv ()
+C11, POSIX.1-2008.
+.TP
+.BR secure_getenv ()
+GNU.
+.SH HISTORY
+.TP
+.BR getenv ()
+POSIX.1-2001, C89, C99, SVr4, 4.3BSD.
+.TP
+.BR secure_getenv ()
+glibc 2.17.
+.SH NOTES
+The strings in the environment list are of the form \fIname=value\fP.
+.P
+As typically implemented,
+.BR getenv ()
+returns a pointer to a string within the environment list.
+The caller must take care not to modify this string,
+since that would change the environment of the process.
+.P
+The implementation of
+.BR getenv ()
+is not required to be reentrant.
+The string pointed to by the return value of
+.BR getenv ()
+may be statically allocated,
+and can be modified by a subsequent call to
+.BR getenv (),
+.BR putenv (3),
+.BR setenv (3),
+or
+.BR unsetenv (3).
+.P
+The "secure execution" mode of
+.BR secure_getenv ()
+is controlled by the
+.B AT_SECURE
+flag contained in the auxiliary vector passed from the kernel to user space.
+.SH SEE ALSO
+.BR clearenv (3),
+.BR getauxval (3),
+.BR putenv (3),
+.BR setenv (3),
+.BR unsetenv (3),
+.BR capabilities (7),
+.BR environ (7)
diff --git a/man/man3/getfsent.3 b/man/man3/getfsent.3
new file mode 100644
index 000000000..eb610a62a
--- /dev/null
+++ b/man/man3/getfsent.3
@@ -0,0 +1,155 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Inspired by a page written by Walter Harms.
+.\"
+.TH getfsent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getfsent, getfsspec, getfsfile, setfsent, endfsent \- handle fstab entries
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <fstab.h>
+.P
+.B "int setfsent(void);"
+.B "struct fstab *getfsent(void);"
+.B "void endfsent(void);"
+.P
+.BI "struct fstab *getfsfile(const char *" mount_point );
+.BI "struct fstab *getfsspec(const char *" special_file );
+.fi
+.SH DESCRIPTION
+These functions read from the file
+.IR /etc/fstab .
+The
+.I struct fstab
+is defined by:
+.P
+.in +4n
+.EX
+struct fstab {
+    char       *fs_spec;       /* block device name */
+    char       *fs_file;       /* mount point */
+    char       *fs_vfstype;    /* filesystem type */
+    char       *fs_mntops;     /* mount options */
+    const char *fs_type;       /* rw/rq/ro/sw/xx option */
+    int         fs_freq;       /* dump frequency, in days */
+    int         fs_passno;     /* pass number on parallel dump */
+};
+.EE
+.in
+.P
+Here the field
+.I fs_type
+contains (on a *BSD system)
+one of the five strings "rw", "rq", "ro", "sw", "xx"
+(read-write, read-write with quota, read-only, swap, ignore).
+.P
+The function
+.BR setfsent ()
+opens the file when required and positions it at the first line.
+.P
+The function
+.BR getfsent ()
+parses the next line from the file.
+(After opening it when required.)
+.P
+The function
+.BR endfsent ()
+closes the file when required.
+.P
+The function
+.BR getfsspec ()
+searches the file from the start and returns the first entry found
+for which the
+.I fs_spec
+field matches the
+.I special_file
+argument.
+.P
+The function
+.BR getfsfile ()
+searches the file from the start and returns the first entry found
+for which the
+.I fs_file
+field matches the
+.I mount_point
+argument.
+.SH RETURN VALUE
+Upon success, the functions
+.BR getfsent (),
+.BR getfsfile (),
+and
+.BR getfsspec ()
+return a pointer to a
+.IR "struct fstab" ,
+while
+.BR setfsent ()
+returns 1.
+Upon failure or end-of-file, these functions return NULL and 0, respectively.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR endfsent (),
+.BR setfsent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:fsent
+T}
+T{
+.na
+.nh
+.BR getfsent (),
+.BR getfsspec (),
+.BR getfsfile ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:fsent locale
+T}
+.TE
+.SH VERSIONS
+Several operating systems have these functions, for example,
+*BSD, SunOS, Digital UNIX, AIX (which also has a
+.BR getfstype ()).
+HP-UX has functions of the same names,
+that however use a
+.I struct checklist
+instead of a
+.IR "struct fstab" ,
+and calls these functions obsolete, superseded by
+.BR getmntent (3).
+.SH STANDARDS
+None.
+.SH HISTORY
+The
+.BR getfsent ()
+function appeared in 4.0BSD; the other four functions appeared in 4.3BSD.
+.SH NOTES
+These functions are not thread-safe.
+.P
+Since Linux allows mounting a block special device in several places,
+and since several devices can have the same mount point, where the
+last device with a given mount point is the interesting one,
+while
+.BR getfsfile ()
+and
+.BR getfsspec ()
+only return the first occurrence, these two functions are not suitable
+for use under Linux.
+.SH SEE ALSO
+.BR getmntent (3),
+.BR fstab (5)
diff --git a/man/man3/getfsfile.3 b/man/man3/getfsfile.3
new file mode 100644
index 000000000..1e6a3eb7e
--- /dev/null
+++ b/man/man3/getfsfile.3
@@ -0,0 +1 @@
+.so man3/getfsent.3
diff --git a/man/man3/getfsspec.3 b/man/man3/getfsspec.3
new file mode 100644
index 000000000..1e6a3eb7e
--- /dev/null
+++ b/man/man3/getfsspec.3
@@ -0,0 +1 @@
+.so man3/getfsent.3
diff --git a/man/man3/getgrent.3 b/man/man3/getgrent.3
new file mode 100644
index 000000000..16b41ff8b
--- /dev/null
+++ b/man/man3/getgrent.3
@@ -0,0 +1,206 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:29:54 1993 by Rik Faith (faith@cs.unc.edu)
+.TH getgrent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getgrent, setgrent, endgrent \- get group file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <grp.h>
+.P
+.B struct group *getgrent(void);
+.P
+.B void setgrent(void);
+.B void endgrent(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR setgrent ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR getgrent (),
+.BR endgrent ():
+.nf
+    Since glibc 2.22:
+        _XOPEN_SOURCE >= 500 || _DEFAULT_SOURCE
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+    glibc 2.21 and earlier
+        _XOPEN_SOURCE >= 500
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+            || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+            || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getgrent ()
+function returns a pointer to a structure containing
+the broken-out fields of a record in the group database
+(e.g., the local group file
+.IR /etc/group ,
+NIS, and LDAP).
+The first time
+.BR getgrent ()
+is called,
+it returns the first entry; thereafter, it returns successive entries.
+.P
+The
+.BR setgrent ()
+function rewinds to the beginning
+of the group database, to allow repeated scans.
+.P
+The
+.BR endgrent ()
+function is used to close the group database
+after all processing has been performed.
+.P
+The \fIgroup\fP structure is defined in \fI<grp.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct group {
+    char   *gr_name;        /* group name */
+    char   *gr_passwd;      /* group password */
+    gid_t   gr_gid;         /* group ID */
+    char  **gr_mem;         /* NULL\-terminated array of pointers
+                               to names of group members */
+};
+.EE
+.in
+.P
+For more information about the fields of this structure, see
+.BR group (5).
+.SH RETURN VALUE
+The
+.BR getgrent ()
+function returns a pointer to a
+.I group
+structure,
+or NULL if there are no more entries or an error occurs.
+.P
+Upon error,
+.I errno
+may be set.
+If one wants to check
+.I errno
+after the call, it should be set to zero before the call.
+.P
+The return value may point to a static area, and may be overwritten
+by subsequent calls to
+.BR getgrent (),
+.BR getgrgid (3),
+or
+.BR getgrnam (3).
+(Do not pass the returned pointer to
+.BR free (3).)
+.SH ERRORS
+.TP
+.B EAGAIN
+The service was temporarily unavailable; try again later.
+For NSS backends in glibc
+this indicates a temporary error talking to the backend.
+The error may correct itself, retrying later is suggested.
+.TP
+.B EINTR
+A signal was caught; see
+.BR signal (7).
+.TP
+.B EIO
+I/O error.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.\" not in POSIX
+.B ENOENT
+A necessary input file cannot be found.
+For NSS backends in glibc
+this indicates the backend is not correctly configured.
+.TP
+.B ENOMEM
+.\" not in POSIX
+Insufficient memory to allocate
+.I group
+structure.
+.TP
+.B ERANGE
+Insufficient buffer space supplied.
+.SH FILES
+.TP
+.I /etc/group
+local group database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getgrent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:grent
+race:grentbuf locale
+T}
+T{
+.na
+.nh
+.BR setgrent (),
+.BR endgrent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:grent locale
+T}
+.TE
+.P
+In the above table,
+.I grent
+in
+.I race:grent
+signifies that if any of the functions
+.BR setgrent (),
+.BR getgrent (),
+or
+.BR endgrent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR fgetgrent (3),
+.BR getgrent_r (3),
+.BR getgrgid (3),
+.BR getgrnam (3),
+.BR getgrouplist (3),
+.BR putgrent (3),
+.BR group (5)
diff --git a/man/man3/getgrent_r.3 b/man/man3/getgrent_r.3
new file mode 100644
index 000000000..6c3018787
--- /dev/null
+++ b/man/man3/getgrent_r.3
@@ -0,0 +1,228 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH getgrent_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getgrent_r, fgetgrent_r \- get group file entry reentrantly
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <grp.h>
+.P
+.BI "int getgrent_r(struct group *restrict " gbuf ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct group **restrict " gbufp );
+.BI "int fgetgrent_r(FILE *restrict " stream ", struct group *restrict " gbuf ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct group **restrict " gbufp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getgrent_r ():
+.nf
+    _GNU_SOURCE
+.fi
+.\" FIXME . The FTM requirements seem inconsistent here.  File a glibc bug?
+.P
+.BR fgetgrent_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The functions
+.BR getgrent_r ()
+and
+.BR fgetgrent_r ()
+are the reentrant versions of
+.BR getgrent (3)
+and
+.BR fgetgrent (3).
+The former reads the next group entry from the stream initialized by
+.BR setgrent (3).
+The latter reads the next group entry from
+.IR stream .
+.P
+The \fIgroup\fP structure is defined in
+.I <grp.h>
+as follows:
+.P
+.in +4n
+.EX
+struct group {
+    char   *gr_name;        /* group name */
+    char   *gr_passwd;      /* group password */
+    gid_t   gr_gid;         /* group ID */
+    char  **gr_mem;         /* NULL\-terminated array of pointers
+                               to names of group members */
+};
+.EE
+.in
+.P
+For more information about the fields of this structure, see
+.BR group (5).
+.P
+The nonreentrant functions return a pointer to static storage,
+where this static storage contains further pointers to group
+name, password, and members.
+The reentrant functions described here return all of that in
+caller-provided buffers.
+First of all there is the buffer
+.I gbuf
+that can hold a \fIstruct group\fP.
+And next the buffer
+.I buf
+of size
+.I buflen
+that can hold additional strings.
+The result of these functions, the \fIstruct group\fP read from the stream,
+is stored in the provided buffer
+.IR *gbuf ,
+and a pointer to this \fIstruct group\fP is returned in
+.IR *gbufp .
+.SH RETURN VALUE
+On success, these functions return 0 and
+.I *gbufp
+is a pointer to the \fIstruct group\fP.
+On error, these functions return an error value and
+.I *gbufp
+is NULL.
+.SH ERRORS
+.TP
+.B ENOENT
+No more entries.
+.TP
+.B ERANGE
+Insufficient buffer space supplied.
+Try again with larger buffer.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getgrent_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:grent locale
+T}
+T{
+.na
+.nh
+.BR fgetgrent_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe
+T}
+.TE
+.P
+In the above table,
+.I grent
+in
+.I race:grent
+signifies that if any of the functions
+.BR setgrent (3),
+.BR getgrent (3),
+.BR endgrent (3),
+or
+.BR getgrent_r ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH VERSIONS
+Other systems use the prototype
+.P
+.in +4n
+.EX
+struct group *getgrent_r(struct group *grp, char *buf,
+                         int buflen);
+.EE
+.in
+.P
+or, better,
+.P
+.in +4n
+.EX
+int getgrent_r(struct group *grp, char *buf, int buflen,
+               FILE **gr_fp);
+.EE
+.in
+.SH STANDARDS
+GNU.
+.SH HISTORY
+These functions are done in a style resembling
+the POSIX version of functions like
+.BR getpwnam_r (3).
+.SH NOTES
+The function
+.BR getgrent_r ()
+is not really reentrant since it shares the reading position
+in the stream with all other threads.
+.SH EXAMPLES
+.\" SRC BEGIN (getgrent_r.c)
+.EX
+#define _GNU_SOURCE
+#include <grp.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#define BUFLEN 4096
+\&
+int
+main(void)
+{
+    struct group grp;
+    struct group *grpp;
+    char buf[BUFLEN];
+    int i;
+\&
+    setgrent();
+    while (1) {
+        i = getgrent_r(&grp, buf, sizeof(buf), &grpp);
+        if (i)
+            break;
+        printf("%s (%jd):", grpp\->gr_name, (intmax_t) grpp\->gr_gid);
+        for (size_t j = 0; ; j++) {
+            if (grpp\->gr_mem[j] == NULL)
+                break;
+            printf(" %s", grpp\->gr_mem[j]);
+        }
+        printf("\en");
+    }
+    endgrent();
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" perhaps add error checking - should use strerror_r
+.\" #include <errno.h>
+.\" #include <stdlib.h>
+.\"         if (i) {
+.\"               if (i == ENOENT)
+.\"                     break;
+.\"               printf("getgrent_r: %s", strerror(i));
+.\"               exit(EXIT_FAILURE);
+.\"         }
+.\" SRC END
+.SH SEE ALSO
+.BR fgetgrent (3),
+.BR getgrent (3),
+.BR getgrgid (3),
+.BR getgrnam (3),
+.BR putgrent (3),
+.BR group (5)
diff --git a/man/man3/getgrgid.3 b/man/man3/getgrgid.3
new file mode 100644
index 000000000..f9a97b451
--- /dev/null
+++ b/man/man3/getgrgid.3
@@ -0,0 +1 @@
+.so man3/getgrnam.3
diff --git a/man/man3/getgrgid_r.3 b/man/man3/getgrgid_r.3
new file mode 100644
index 000000000..f9a97b451
--- /dev/null
+++ b/man/man3/getgrgid_r.3
@@ -0,0 +1 @@
+.so man3/getgrnam.3
diff --git a/man/man3/getgrnam.3 b/man/man3/getgrnam.3
new file mode 100644
index 000000000..2010e6d1c
--- /dev/null
+++ b/man/man3/getgrnam.3
@@ -0,0 +1,260 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2003-11-15 by aeb
+.\"
+.TH getgrnam 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getgrnam, getgrnam_r, getgrgid, getgrgid_r \- get group file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <grp.h>
+.P
+.BI "struct group *getgrnam(const char *" name );
+.BI "struct group *getgrgid(gid_t " gid );
+.P
+.BI "int getgrnam_r(const char *restrict " name \
+", struct group *restrict " grp ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct group **restrict " result );
+.BI "int getgrgid_r(gid_t " gid ", struct group *restrict " grp ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct group **restrict " result );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getgrnam_r (),
+.BR getgrgid_r ():
+.nf
+    _POSIX_C_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getgrnam ()
+function returns a pointer to a structure containing
+the broken-out fields of the record in the group database
+(e.g., the local group file
+.IR /etc/group ,
+NIS, and LDAP)
+that matches the group name
+.IR name .
+.P
+The
+.BR getgrgid ()
+function returns a pointer to a structure containing
+the broken-out fields of the record in the group database
+that matches the group ID
+.IR gid .
+.P
+The \fIgroup\fP structure is defined in \fI<grp.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct group {
+    char   *gr_name;        /* group name */
+    char   *gr_passwd;      /* group password */
+    gid_t   gr_gid;         /* group ID */
+    char  **gr_mem;         /* NULL\-terminated array of pointers
+                               to names of group members */
+};
+.EE
+.in
+.P
+For more information about the fields of this structure, see
+.BR group (5).
+.P
+The
+.BR getgrnam_r ()
+and
+.BR getgrgid_r ()
+functions obtain the same information as
+.BR getgrnam ()
+and
+.BR getgrgid (),
+but store the retrieved
+.I group
+structure
+in the space pointed to by
+.IR grp .
+The string fields pointed to by the members of the
+.I group
+structure are stored in the buffer
+.I buf
+of size
+.IR buflen .
+A pointer to the result (in case of success) or NULL (in case no entry
+was found or an error occurred) is stored in
+.IR *result .
+.P
+The call
+.P
+.in +4n
+.EX
+sysconf(_SC_GETGR_R_SIZE_MAX)
+.EE
+.in
+.P
+returns either \-1, without changing
+.IR errno ,
+or an initial suggested size for
+.IR buf .
+(If this size is too small,
+the call fails with
+.BR ERANGE ,
+in which case the caller can retry with a larger buffer.)
+.SH RETURN VALUE
+The
+.BR getgrnam ()
+and
+.BR getgrgid ()
+functions return a pointer to a
+.I group
+structure, or NULL if the matching entry
+is not found or an error occurs.
+If an error occurs,
+.I errno
+is set to indicate the error.
+If one wants to check
+.I errno
+after the call, it should be set to zero before the call.
+.P
+The return value may point to a static area, and may be overwritten
+by subsequent calls to
+.BR getgrent (3),
+.BR getgrgid (),
+or
+.BR getgrnam ().
+(Do not pass the returned pointer to
+.BR free (3).)
+.P
+On success,
+.BR getgrnam_r ()
+and
+.BR getgrgid_r ()
+return zero, and set
+.I *result
+to
+.IR grp .
+If no matching group record was found,
+these functions return 0 and store NULL in
+.IR *result .
+In case of error, an error number is returned, and NULL is stored in
+.IR *result .
+.SH ERRORS
+.TP
+.BR 0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ..."
+The given
+.I name
+or
+.I gid
+was not found.
+.TP
+.B EINTR
+A signal was caught; see
+.BR signal (7).
+.TP
+.B EIO
+I/O error.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+.\" not in POSIX
+Insufficient memory to allocate
+.I group
+structure.
+.\" to allocate the group structure, or to allocate buffers
+.TP
+.B ERANGE
+Insufficient buffer space supplied.
+.SH FILES
+.TP
+.I /etc/group
+local group database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getgrnam ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:grnam locale
+T}
+T{
+.na
+.nh
+.BR getgrgid ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:grgid locale
+T}
+T{
+.na
+.nh
+.BR getgrnam_r (),
+.BR getgrgid_r ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+The formulation given above under "RETURN VALUE" is from POSIX.1.
+.\" POSIX.1-2001, POSIX.1-2008
+It does not call "not found" an error, hence does not specify what value
+.I errno
+might have in this situation.
+But that makes it impossible to recognize
+errors.
+One might argue that according to POSIX
+.I errno
+should be left unchanged if an entry is not found.
+Experiments on various
+UNIX-like systems show that lots of different values occur in this
+situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM, and probably others.
+.\" more precisely:
+.\" AIX 5.1 - gives ESRCH
+.\" OSF1 4.0g - gives EWOULDBLOCK
+.\" libc, glibc up to glibc 2.6, Irix 6.5 - give ENOENT
+.\" since glibc 2.7 - give 0
+.\" FreeBSD 4.8, OpenBSD 3.2, NetBSD 1.6 - give EPERM
+.\" SunOS 5.8 - gives EBADF
+.\" Tru64 5.1b, HP-UX-11i, SunOS 5.7 - give 0
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR endgrent (3),
+.BR fgetgrent (3),
+.BR getgrent (3),
+.BR getpwnam (3),
+.BR setgrent (3),
+.BR group (5)
diff --git a/man/man3/getgrnam_r.3 b/man/man3/getgrnam_r.3
new file mode 100644
index 000000000..f9a97b451
--- /dev/null
+++ b/man/man3/getgrnam_r.3
@@ -0,0 +1 @@
+.so man3/getgrnam.3
diff --git a/man/man3/getgrouplist.3 b/man/man3/getgrouplist.3
new file mode 100644
index 000000000..61d3b7a9b
--- /dev/null
+++ b/man/man3/getgrouplist.3
@@ -0,0 +1,205 @@
+'\" t
+.\" Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk
+.\" <mtk.manpages@gmail.com>
+.\"
+.\" A few pieces remain from an earlier version written in
+.\" 2002 by Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getgrouplist 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getgrouplist \- get list of groups to which a user belongs
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <grp.h>
+.P
+.BI "int getgrouplist(const char *" user ", gid_t " group ,
+.BI "                 gid_t *" groups ", int *" ngroups );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getgrouplist ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getgrouplist ()
+function scans the group database (see
+.BR group (5))
+to obtain the list of groups that
+.I user
+belongs to.
+Up to
+.I *ngroups
+of these groups are returned in the array
+.IR groups .
+.P
+If it was not among the groups defined for
+.I user
+in the group database, then
+.I group
+is included in the list of groups returned by
+.BR getgrouplist ();
+typically this argument is specified as the group ID from
+the password record for
+.IR user .
+.P
+The
+.I ngroups
+argument is a value-result argument:
+on return it always contains the number of groups found for
+.IR user ,
+including
+.IR group ;
+this value may be greater than the number of groups stored in
+.IR groups .
+.SH RETURN VALUE
+If the number of groups of which
+.I user
+is a member is less than or equal to
+.IR *ngroups ,
+then the value
+.I *ngroups
+is returned.
+.P
+If the user is a member of more than
+.I *ngroups
+groups, then
+.BR getgrouplist ()
+returns \-1.
+In this case, the value returned in
+.I *ngroups
+can be used to resize the buffer passed to a further call to
+.BR getgrouplist ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getgrouplist ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.2.4.
+.SH BUGS
+Before glibc 2.3.3,
+the implementation of this function contains a buffer-overrun bug:
+it returns the complete list of groups for
+.I user
+in the array
+.IR groups ,
+even when the number of groups exceeds
+.IR *ngroups .
+.SH EXAMPLES
+The program below displays the group list for the user named in its
+first command-line argument.
+The second command-line argument specifies the
+.I ngroups
+value to be supplied to
+.BR getgrouplist ().
+The following shell session shows examples of the use of this program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out cecilia 0"
+getgrouplist() returned \-1; ngroups = 3
+.RB "$" " ./a.out cecilia 3"
+ngroups = 3
+16 (dialout)
+33 (video)
+100 (users)
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (getgrouplist.c)
+.EX
+#include <errno.h>
+#include <grp.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int            ngroups;
+    gid_t          *groups;
+    struct group   *gr;
+    struct passwd  *pw;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <user> <ngroups>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    ngroups = atoi(argv[2]);
+\&
+    groups = malloc(sizeof(*groups) * ngroups);
+    if (groups == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Fetch passwd structure (contains first group ID for user). */
+\&
+    errno = 0;
+    pw = getpwnam(argv[1]);
+    if (pw == NULL) {
+        if (errno)
+            perror("getpwnam");
+        else
+            fprintf(stderr, "no such user\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Retrieve group list. */
+\&
+    if (getgrouplist(argv[1], pw\->pw_gid, groups, &ngroups) == \-1) {
+        fprintf(stderr, "getgrouplist() returned \-1; ngroups = %d\en",
+                ngroups);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Display list of retrieved groups, along with group names. */
+\&
+    fprintf(stderr, "ngroups = %d\en", ngroups);
+    for (int j = 0; j < ngroups; j++) {
+        printf("%d", groups[j]);
+        gr = getgrgid(groups[j]);
+        if (gr != NULL)
+            printf(" (%s)", gr\->gr_name);
+        printf("\en");
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getgroups (2),
+.BR setgroups (2),
+.BR getgrent (3),
+.BR group_member (3),
+.BR group (5),
+.BR passwd (5)
diff --git a/man/man3/gethostbyaddr.3 b/man/man3/gethostbyaddr.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/gethostbyaddr.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/gethostbyaddr_r.3 b/man/man3/gethostbyaddr_r.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/gethostbyaddr_r.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/gethostbyname.3 b/man/man3/gethostbyname.3
new file mode 100644
index 000000000..a881b2c10
--- /dev/null
+++ b/man/man3/gethostbyname.3
@@ -0,0 +1,553 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-05-22, David Metcalfe
+.\" Modified 1993-07-25, Rik Faith (faith@cs.unc.edu)
+.\" Modified 1997-02-16, Andries Brouwer (aeb@cwi.nl)
+.\" Modified 1998-12-21, Andries Brouwer (aeb@cwi.nl)
+.\" Modified 2000-08-12, Andries Brouwer (aeb@cwi.nl)
+.\" Modified 2001-05-19, Andries Brouwer (aeb@cwi.nl)
+.\" Modified 2002-08-05, Michael Kerrisk
+.\" Modified 2004-10-31, Andries Brouwer
+.\"
+.TH gethostbyname 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gethostbyname, gethostbyaddr, sethostent, gethostent, endhostent,
+h_errno,
+herror, hstrerror,
+gethostbyaddr_r,
+gethostbyname2, gethostbyname2_r, gethostbyname_r,
+gethostent_r \- get network host entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.BI "void sethostent(int " stayopen );
+.B void endhostent(void);
+.P
+.B [[deprecated]] extern int h_errno;
+.P
+.BI "[[deprecated]] struct hostent *gethostbyname(const char *" name );
+.BI "[[deprecated]] struct hostent *gethostbyaddr(const void " addr [. len ],
+.BI "                                             socklen_t " len ", int " type );
+.P
+.BI "[[deprecated]] void herror(const char *" s );
+.BI "[[deprecated]] const char *hstrerror(int " err );
+.P
+/* System V/POSIX extension */
+.B struct hostent *gethostent(void);
+.P
+/* GNU extensions */
+.B [[deprecated]]
+.BI "struct hostent *gethostbyname2(const char *" name ", int " af );
+.P
+.BI "int gethostent_r(struct hostent *restrict " ret ,
+.BI "                 char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                 struct hostent **restrict " result ,
+.BI "                 int *restrict " h_errnop );
+.P
+.B [[deprecated]]
+.BI "int gethostbyaddr_r(const void " addr "[restrict ." len "], socklen_t " len ,
+.BI "                 int " type ,
+.BI "                 struct hostent *restrict " ret ,
+.BI "                 char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                 struct hostent **restrict " result ,
+.BI "                 int *restrict " h_errnop );
+.B [[deprecated]]
+.BI "int gethostbyname_r(const char *restrict " name ,
+.BI "                 struct hostent *restrict " ret ,
+.BI "                 char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                 struct hostent **restrict " result ,
+.BI "                 int *restrict " h_errnop );
+.B [[deprecated]]
+.BI "int gethostbyname2_r(const char *restrict " name ", int " af,
+.BI "                 struct hostent *restrict " ret ,
+.BI "                 char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                 struct hostent **restrict " result ,
+.BI "                 int *restrict " h_errnop );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR gethostbyname2 (),
+.BR gethostent_r (),
+.BR gethostbyaddr_r (),
+.BR gethostbyname_r (),
+.BR gethostbyname2_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc up to and including 2.19:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR herror (),
+.BR hstrerror ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.8 to glibc 2.19:
+        _BSD_SOURCE || _SVID_SOURCE
+    Before glibc 2.8:
+        none
+.fi
+.P
+.BR h_errno :
+.nf
+    Since glibc 2.19
+        _DEFAULT_SOURCE || _POSIX_C_SOURCE < 200809L
+    glibc 2.12 to glibc 2.19:
+        _BSD_SOURCE || _SVID_SOURCE || _POSIX_C_SOURCE < 200809L
+    Before glibc 2.12:
+        none
+.fi
+.SH DESCRIPTION
+The
+.BR gethostbyname* (),
+.BR gethostbyaddr* (),
+.BR herror (),
+and
+.BR hstrerror ()
+functions are obsolete.
+Applications should use
+.BR getaddrinfo (3),
+.BR getnameinfo (3),
+and
+.BR gai_strerror (3)
+instead.
+.P
+The
+.BR sethostent ()
+function specifies, if \fIstayopen\fP is true (1),
+that a connected TCP socket should be used for the name server queries and
+that the connection should remain open during successive queries.
+Otherwise, name server queries will use UDP datagrams.
+.P
+The
+.BR endhostent ()
+function ends the use of a TCP connection for name
+server queries.
+.P
+The
+.BR gethostbyname ()
+function returns a structure of type
+.I hostent
+for the given host
+.IR name .
+Here
+.I name
+is either a hostname or an IPv4 address in standard dot notation (as for
+.BR inet_addr (3)).
+If
+.I name
+is an IPv4 address, no lookup is performed and
+.BR gethostbyname ()
+simply copies
+.I name
+into the
+.I h_name
+field and its
+.I struct in_addr
+equivalent into the
+.I h_addr_list[0]
+field of the returned
+.I hostent
+structure.
+If
+.I name
+doesn't end in a dot and the environment variable
+.B HOSTALIASES
+is set, the alias file pointed to by
+.B HOSTALIASES
+will first be searched for
+.I name
+(see
+.BR hostname (7)
+for the file format).
+The current domain and its parents are searched unless \fIname\fP
+ends in a dot.
+.P
+The
+.BR gethostbyaddr ()
+function returns a structure of type \fIhostent\fP
+for the given host address \fIaddr\fP of length \fIlen\fP and address type
+\fItype\fP.
+Valid address types are
+.B AF_INET
+and
+.B AF_INET6
+(defined in
+.IR <sys/socket.h> ).
+The host address argument is a pointer to a struct of a type depending
+on the address type, for example a \fIstruct in_addr *\fP (probably
+obtained via a call to
+.BR inet_addr (3))
+for address type
+.BR AF_INET .
+.P
+The (obsolete)
+.BR herror ()
+function prints the error message associated
+with the current value of \fIh_errno\fP on \fIstderr\fP.
+.P
+The (obsolete)
+.BR hstrerror ()
+function takes an error number
+(typically \fIh_errno\fP) and returns the corresponding message string.
+.P
+The domain name queries carried out by
+.BR gethostbyname ()
+and
+.BR gethostbyaddr ()
+rely on the Name Service Switch
+.RB ( nsswitch.conf (5))
+configured sources or a local name server
+.RB ( named (8)).
+The default action is to query the Name Service Switch
+.RB ( nsswitch.conf (5))
+configured sources, failing that, a local name server
+.RB ( named (8)).
+.\"
+.SS Historical
+The
+.BR nsswitch.conf (5)
+file is the modern way of controlling the order of host lookups.
+.P
+In glibc 2.4 and earlier, the
+.I order
+keyword was used to control the order of host lookups as defined in
+.I /etc/host.conf
+.RB ( host.conf (5)).
+.P
+The \fIhostent\fP structure is defined in \fI<netdb.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct hostent {
+    char  *h_name;            /* official name of host */
+    char **h_aliases;         /* alias list */
+    int    h_addrtype;        /* host address type */
+    int    h_length;          /* length of address */
+    char **h_addr_list;       /* list of addresses */
+}
+#define h_addr h_addr_list[0] /* for backward compatibility */
+.EE
+.in
+.P
+The members of the \fIhostent\fP structure are:
+.TP
+.I h_name
+The official name of the host.
+.TP
+.I h_aliases
+An array of alternative names for the host, terminated by a null pointer.
+.TP
+.I h_addrtype
+The type of address; always
+.B AF_INET
+or
+.B AF_INET6
+at present.
+.TP
+.I h_length
+The length of the address in bytes.
+.TP
+.I h_addr_list
+An array of pointers to network addresses for the host (in network byte
+order), terminated by a null pointer.
+.TP
+.I h_addr
+The first address in \fIh_addr_list\fP for backward compatibility.
+.SH RETURN VALUE
+The
+.BR gethostbyname ()
+and
+.BR gethostbyaddr ()
+functions return the
+.I hostent
+structure or a null pointer if an error occurs.
+On error, the
+.I h_errno
+variable holds an error number.
+When non-NULL, the return value may point at static data, see the notes below.
+.SH ERRORS
+The variable \fIh_errno\fP can have the following values:
+.TP
+.B HOST_NOT_FOUND
+The specified host is unknown.
+.TP
+.B NO_DATA
+The requested name is valid but does not have an IP address.
+Another type of request to the name server for this domain
+may return an answer.
+The constant
+.B NO_ADDRESS
+is a synonym for
+.BR NO_DATA .
+.TP
+.B NO_RECOVERY
+A nonrecoverable name server error occurred.
+.TP
+.B TRY_AGAIN
+A temporary error occurred on an authoritative name server.
+Try again later.
+.SH FILES
+.TP
+.I /etc/host.conf
+resolver configuration file
+.TP
+.I /etc/hosts
+host database file
+.TP
+.I /etc/nsswitch.conf
+name service switch configuration
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR gethostbyname ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:hostbyname env
+locale
+T}
+T{
+.na
+.nh
+.BR gethostbyaddr ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:hostbyaddr env
+locale
+T}
+T{
+.na
+.nh
+.BR sethostent (),
+.BR endhostent (),
+.BR gethostent_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:hostent env
+locale
+T}
+T{
+.na
+.nh
+.BR herror (),
+.BR hstrerror ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR gethostent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:hostent
+race:hostentbuf env locale
+T}
+T{
+.na
+.nh
+.BR gethostbyname2 ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:hostbyname2
+env locale
+T}
+T{
+.na
+.nh
+.BR gethostbyaddr_r (),
+.BR gethostbyname_r (),
+.BR gethostbyname2_r ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.P
+In the above table,
+.I hostent
+in
+.I race:hostent
+signifies that if any of the functions
+.BR sethostent (),
+.BR gethostent (),
+.BR gethostent_r (),
+or
+.BR \%endhostent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH STANDARDS
+.TP
+.BR sethostent ()
+.TQ
+.BR endhostent ()
+.TQ
+.BR gethostent ()
+POSIX.1-2008.
+.TP
+.BR gethostent_r ()
+GNU.
+.TP
+Others:
+None.
+.SH HISTORY
+.TP
+.BR sethostent ()
+.TQ
+.BR endhostent ()
+.TQ
+.BR gethostent ()
+POSIX.1-2001.
+.TP
+.BR gethostbyname ()
+.TQ
+.BR gethostbyaddr ()
+.TQ
+.I h_errno
+Marked obsolescent in POSIX.1-2001.
+Removed in POSIX.1-2008,
+recommending the use of
+.BR getaddrinfo (3)
+and
+.BR getnameinfo (3)
+instead.
+.SH NOTES
+The functions
+.BR gethostbyname ()
+and
+.BR gethostbyaddr ()
+may return pointers to static data, which may be overwritten by
+later calls.
+Copying the
+.I struct hostent
+does not suffice, since it contains pointers; a deep copy is required.
+.P
+In the original BSD implementation the
+.I len
+argument
+of
+.BR gethostbyname ()
+was an
+.IR int .
+The SUSv2 standard is buggy and declares the
+.I len
+argument of
+.BR gethostbyaddr ()
+to be of type
+.IR size_t .
+(That is wrong, because it has to be
+.IR int ,
+and
+.I size_t
+is not.
+POSIX.1-2001 makes it
+.IR socklen_t ,
+which is OK.)
+See also
+.BR accept (2).
+.P
+The BSD prototype for
+.BR gethostbyaddr ()
+uses
+.I "const char\ *"
+for the first argument.
+.SS System V/POSIX extension
+POSIX requires the
+.BR gethostent ()
+call, which should return the next entry in the host data base.
+When using DNS/BIND this does not make much sense, but it may
+be reasonable if the host data base is a file that can be read
+line by line.
+On many systems, a routine of this name reads
+from the file
+.IR /etc/hosts .
+.\" e.g., Linux, FreeBSD, UnixWare, HP-UX
+It may be available only when the library was built without DNS support.
+.\" e.g., FreeBSD, AIX
+The glibc version will ignore ipv6 entries.
+This function is not reentrant,
+and glibc adds a reentrant version
+.BR gethostent_r ().
+.SS GNU extensions
+glibc2 also has a
+.BR gethostbyname2 ()
+that works like
+.BR gethostbyname (),
+but permits to specify the address family to which the address must belong.
+.P
+glibc2 also has reentrant versions
+.BR gethostent_r (),
+.BR gethostbyaddr_r (),
+.BR gethostbyname_r (),
+and
+.BR gethostbyname2_r ().
+The caller supplies a
+.I hostent
+structure
+.I ret
+which will be filled in on success, and a temporary work buffer
+.I buf
+of size
+.IR buflen .
+After the call,
+.I result
+will point to the result on success.
+In case of an error
+or if no entry is found
+.I result
+will be NULL.
+The functions return 0 on success and a nonzero error number on failure.
+In addition to the errors returned by the nonreentrant
+versions of these functions, if
+.I buf
+is too small, the functions will return
+.BR ERANGE ,
+and the call should be retried with a larger buffer.
+The global variable
+.I h_errno
+is not modified, but the address of a variable in which to store error numbers
+is passed in
+.IR h_errnop .
+.SH BUGS
+.BR gethostbyname ()
+does not recognize components of a dotted IPv4 address string
+that are expressed in hexadecimal.
+.\" http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=482973
+.SH SEE ALSO
+.BR getaddrinfo (3),
+.\" .BR getipnodebyaddr (3),
+.\" .BR getipnodebyname (3),
+.BR getnameinfo (3),
+.BR inet (3),
+.BR inet_ntop (3),
+.BR inet_pton (3),
+.BR resolver (3),
+.BR hosts (5),
+.BR nsswitch.conf (5),
+.BR hostname (7),
+.BR named (8)
+.\" .BR resolv+ (8)
diff --git a/man/man3/gethostbyname2.3 b/man/man3/gethostbyname2.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/gethostbyname2.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/gethostbyname2_r.3 b/man/man3/gethostbyname2_r.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/gethostbyname2_r.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/gethostbyname_r.3 b/man/man3/gethostbyname_r.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/gethostbyname_r.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/gethostent.3 b/man/man3/gethostent.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/gethostent.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/gethostent_r.3 b/man/man3/gethostent_r.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/gethostent_r.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/gethostid.3 b/man/man3/gethostid.3
new file mode 100644
index 000000000..daaaf548a
--- /dev/null
+++ b/man/man3/gethostid.3
@@ -0,0 +1,149 @@
+'\" t
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" Updated with additions from Mitchum DSouza <m.dsouza@mrc-apu.cam.ac.uk>
+.\" Portions Copyright 1993 Mitchum DSouza <m.dsouza@mrc-apu.cam.ac.uk>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Tue Oct 22 00:22:35 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.TH gethostid 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gethostid, sethostid \- get or set the unique identifier of the current host
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B long gethostid(void);
+.BI "int sethostid(long " hostid );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR gethostid ():
+.nf
+    Since glibc 2.20:
+        _DEFAULT_SOURCE || _XOPEN_SOURCE >= 500
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"        || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.P
+.BR sethostid ():
+.nf
+    Since glibc 2.21:
+.\"             commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+.BR gethostid ()
+and
+.BR sethostid ()
+respectively get or set a unique 32-bit identifier for the current machine.
+The 32-bit identifier was intended to be unique among all UNIX systems in
+existence.
+This normally resembles the Internet address for the local
+machine, as returned by
+.BR gethostbyname (3),
+and thus usually never needs to be set.
+.P
+The
+.BR sethostid ()
+call is restricted to the superuser.
+.SH RETURN VALUE
+.BR gethostid ()
+returns the 32-bit identifier for the current host as set by
+.BR sethostid ().
+.P
+On success,
+.BR sethostid ()
+returns 0; on error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR sethostid ()
+can fail with the following errors:
+.TP
+.B EACCES
+The caller did not have permission to write to the file used
+to store the host ID.
+.TP
+.B EPERM
+The calling process's effective user or group ID is not the same
+as its corresponding real ID.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR gethostid ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe hostid env locale
+T}
+T{
+.na
+.nh
+.BR sethostid ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe const:hostid
+T}
+.TE
+.SH VERSIONS
+In the glibc implementation, the
+.I hostid
+is stored in the file
+.IR /etc/hostid .
+(Before glibc 2.2, the file
+.I /var/adm/hostid
+was used.)
+.\" libc5 used /etc/hostid; libc4 didn't have these functions
+.P
+In the glibc implementation, if
+.BR gethostid ()
+cannot open the file containing the host ID,
+then it obtains the hostname using
+.BR gethostname (2),
+passes that hostname to
+.BR gethostbyname_r (3)
+in order to obtain the host's IPv4 address,
+and returns a value obtained by bit-twiddling the IPv4 address.
+(This value may not be unique.)
+.SH STANDARDS
+.TP
+.BR gethostid ()
+POSIX.1-2008.
+.TP
+.BR sethostid ()
+None.
+.SH HISTORY
+4.2BSD; dropped in 4.4BSD.
+SVr4 and POSIX.1-2001 include
+.BR gethostid ()
+but not
+.BR sethostid ().
+.SH BUGS
+It is impossible to ensure that the identifier is globally unique.
+.SH SEE ALSO
+.BR hostid (1),
+.BR gethostbyname (3)
diff --git a/man/man3/getifaddrs.3 b/man/man3/getifaddrs.3
new file mode 100644
index 000000000..3ecaf71c0
--- /dev/null
+++ b/man/man3/getifaddrs.3
@@ -0,0 +1,313 @@
+'\" t
+.\" Copyright (c) 2008 Petr Baudis <pasky@suse.cz>
+.\" and copyright (c) 2009, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\"
+.\" 2008-12-08 Petr Baudis <pasky@suse.cz>
+.\"    Rewrite the BSD manpage in the Linux man pages style and account
+.\"    for glibc specificities, provide an example.
+.\" 2009-01-14 mtk, many edits and changes, rewrote example program.
+.\"
+.TH getifaddrs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getifaddrs, freeifaddrs \- get interface addresses
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <ifaddrs.h>
+.P
+.BI "int getifaddrs(struct ifaddrs **" "ifap" );
+.BI "void freeifaddrs(struct ifaddrs *" "ifa" );
+.fi
+.SH DESCRIPTION
+The
+.BR getifaddrs ()
+function creates a linked list of structures describing
+the network interfaces of the local system,
+and stores the address of the first item of the list in
+.IR *ifap .
+The list consists of
+.I ifaddrs
+structures, defined as follows:
+.P
+.in +4n
+.EX
+struct ifaddrs {
+    struct ifaddrs  *ifa_next;    /* Next item in list */
+    char            *ifa_name;    /* Name of interface */
+    unsigned int     ifa_flags;   /* Flags from SIOCGIFFLAGS */
+    struct sockaddr *ifa_addr;    /* Address of interface */
+    struct sockaddr *ifa_netmask; /* Netmask of interface */
+    union {
+        struct sockaddr *ifu_broadaddr;
+                         /* Broadcast address of interface */
+        struct sockaddr *ifu_dstaddr;
+                         /* Point\-to\-point destination address */
+    } ifa_ifu;
+#define              ifa_broadaddr ifa_ifu.ifu_broadaddr
+#define              ifa_dstaddr   ifa_ifu.ifu_dstaddr
+    void            *ifa_data;    /* Address\-specific data */
+};
+.EE
+.in
+.P
+The
+.I ifa_next
+field contains a pointer to the next structure on the list,
+or NULL if this is the last item of the list.
+.P
+The
+.I ifa_name
+points to the null-terminated interface name.
+.\" The constant
+.\" .B IF NAMESIZE
+.\" indicates the maximum length of this field.
+.P
+The
+.I ifa_flags
+field contains the interface flags, as returned by the
+.B SIOCGIFFLAGS
+.BR ioctl (2)
+operation (see
+.BR netdevice (7)
+for a list of these flags).
+.P
+The
+.I ifa_addr
+field points to a structure containing the interface address.
+(The
+.I sa_family
+subfield should be consulted to determine the format of the
+address structure.)
+This field may contain a null pointer.
+.P
+The
+.I ifa_netmask
+field points to a structure containing the netmask associated with
+.IR ifa_addr ,
+if applicable for the address family.
+This field may contain a null pointer.
+.P
+Depending on whether the bit
+.B IFF_BROADCAST
+or
+.B IFF_POINTOPOINT
+is set in
+.I ifa_flags
+(only one can be set at a time),
+either
+.I ifa_broadaddr
+will contain the broadcast address associated with
+.I ifa_addr
+(if applicable for the address family) or
+.I ifa_dstaddr
+will contain the destination address of the point-to-point interface.
+.P
+The
+.I ifa_data
+field points to a buffer containing address-family-specific data;
+this field may be NULL if there is no such data for this interface.
+.P
+The data returned by
+.BR getifaddrs ()
+is dynamically allocated and should be freed using
+.BR freeifaddrs ()
+when no longer needed.
+.SH RETURN VALUE
+On success,
+.BR getifaddrs ()
+returns zero;
+on error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR getifaddrs ()
+may fail and set
+.I errno
+for any of the errors specified for
+.BR socket (2),
+.BR bind (2),
+.BR getsockname (2),
+.BR recvmsg (2),
+.BR sendto (2),
+.BR malloc (3),
+or
+.BR realloc (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getifaddrs (),
+.BR freeifaddrs ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+This function first appeared in BSDi and is
+present on the BSD systems, but with slightly different
+semantics documented\[em]returning one entry per interface,
+not per address.
+This means
+.I ifa_addr
+and other fields can actually be NULL if the interface has no address,
+and no link-level address is returned if the interface has an IP address
+assigned.
+Also, the way of choosing either
+.I ifa_broadaddr
+or
+.I ifa_dstaddr
+differs on various systems.
+.\" , but the BSD-derived documentation generally
+.\" appears to be confused and obsolete on this point.
+.\" i.e., commonly it still says one of them will be NULL, even if
+.\" the ifa_ifu union is already present
+.P
+.BR getifaddrs ()
+first appeared in glibc 2.3, but before glibc 2.3.3,
+the implementation supported only IPv4 addresses;
+IPv6 support was added in glibc 2.3.3.
+Support of address families other than IPv4 is available only
+on kernels that support netlink.
+.SH NOTES
+The addresses returned on Linux will usually be the IPv4 and IPv6 addresses
+assigned to the interface, but also one
+.B AF_PACKET
+address per interface containing lower-level details about the interface
+and its physical layer.
+In this case, the
+.I ifa_data
+field may contain a pointer to a
+.IR "struct rtnl_link_stats" ,
+defined in
+.I <linux/if_link.h>
+(in Linux 2.4 and earlier,
+.IR "struct net_device_stats" ,
+defined in
+.IR <linux/netdevice.h> ),
+which contains various interface attributes and statistics.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR getifaddrs (),
+.BR freeifaddrs (),
+and
+.BR getnameinfo (3).
+Here is what we see when running this program on one system:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+lo       AF_PACKET (17)
+                tx_packets =        524; rx_packets =        524
+                tx_bytes   =      38788; rx_bytes   =      38788
+wlp3s0   AF_PACKET (17)
+                tx_packets =     108391; rx_packets =     130245
+                tx_bytes   =   30420659; rx_bytes   =   94230014
+em1      AF_PACKET (17)
+                tx_packets =          0; rx_packets =          0
+                tx_bytes   =          0; rx_bytes   =          0
+lo       AF_INET (2)
+                address: <127.0.0.1>
+wlp3s0   AF_INET (2)
+                address: <192.168.235.137>
+lo       AF_INET6 (10)
+                address: <::1>
+wlp3s0   AF_INET6 (10)
+                address: <fe80::7ee9:d3ff:fef5:1a91%wlp3s0>
+.EE
+.in
+.SS Program source
+\&
+.EX
+#define _GNU_SOURCE     /* To get defns of NI_MAXSERV and NI_MAXHOST */
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <ifaddrs.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <linux/if_link.h>
+\&
+int main(int argc, char *argv[])
+{
+    struct ifaddrs *ifaddr;
+    int family, s;
+    char host[NI_MAXHOST];
+\&
+    if (getifaddrs(&ifaddr) == \-1) {
+        perror("getifaddrs");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Walk through linked list, maintaining head pointer so we
+       can free list later. */
+\&
+    for (struct ifaddrs *ifa = ifaddr; ifa != NULL;
+             ifa = ifa\->ifa_next) {
+        if (ifa\->ifa_addr == NULL)
+            continue;
+\&
+        family = ifa\->ifa_addr\->sa_family;
+\&
+        /* Display interface name and family (including symbolic
+           form of the latter for the common families). */
+\&
+        printf("%\-8s %s (%d)\en",
+               ifa\->ifa_name,
+               (family == AF_PACKET) ? "AF_PACKET" :
+               (family == AF_INET) ? "AF_INET" :
+               (family == AF_INET6) ? "AF_INET6" : "???",
+               family);
+\&
+        /* For an AF_INET* interface address, display the address. */
+\&
+        if (family == AF_INET || family == AF_INET6) {
+            s = getnameinfo(ifa\->ifa_addr,
+                    (family == AF_INET) ? sizeof(struct sockaddr_in) :
+                                          sizeof(struct sockaddr_in6),
+                    host, NI_MAXHOST,
+                    NULL, 0, NI_NUMERICHOST);
+            if (s != 0) {
+                printf("getnameinfo() failed: %s\en", gai_strerror(s));
+                exit(EXIT_FAILURE);
+            }
+\&
+            printf("\et\etaddress: <%s>\en", host);
+\&
+        } else if (family == AF_PACKET && ifa\->ifa_data != NULL) {
+            struct rtnl_link_stats *stats = ifa\->ifa_data;
+\&
+            printf("\et\ettx_packets = %10u; rx_packets = %10u\en"
+                   "\et\ettx_bytes   = %10u; rx_bytes   = %10u\en",
+                   stats\->tx_packets, stats\->rx_packets,
+                   stats\->tx_bytes, stats\->rx_bytes);
+        }
+    }
+\&
+    freeifaddrs(ifaddr);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR bind (2),
+.BR getsockname (2),
+.BR socket (2),
+.BR packet (7),
+.BR ifconfig (8)
diff --git a/man/man3/getipnodebyaddr.3 b/man/man3/getipnodebyaddr.3
new file mode 100644
index 000000000..82e01df46
--- /dev/null
+++ b/man/man3/getipnodebyaddr.3
@@ -0,0 +1 @@
+.so man3/getipnodebyname.3
diff --git a/man/man3/getipnodebyname.3 b/man/man3/getipnodebyname.3
new file mode 100644
index 000000000..09808542b
--- /dev/null
+++ b/man/man3/getipnodebyname.3
@@ -0,0 +1,253 @@
+.\" Copyright 2000 Sam Varshavchik <mrsam@courier-mta.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References: RFC 2553
+.TH getipnodebyname 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getipnodebyname, getipnodebyaddr, freehostent \- get network
+hostnames and addresses
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <sys/socket.h>
+.B #include <netdb.h>
+.P
+.BI "[[deprecated]] struct hostent *getipnodebyname(const char *" name ", int " af ,
+.BI "                                            int " flags ", int *" error_num );
+.BI "[[deprecated]] struct hostent *getipnodebyaddr(const void " addr [. len ],
+.BI "                                            size_t " len ", int " af ,
+.BI "                                            int *" "error_num" );
+.BI "[[deprecated]] void freehostent(struct hostent *" "ip" );
+.fi
+.SH DESCRIPTION
+These functions are deprecated (and unavailable in glibc).
+Use
+.BR getaddrinfo (3)
+and
+.BR getnameinfo (3)
+instead.
+.P
+The
+.BR getipnodebyname ()
+and
+.BR getipnodebyaddr ()
+functions return the names and addresses of a network host.
+These functions return a pointer to the
+following structure:
+.P
+.in +4n
+.EX
+struct hostent {
+    char  *h_name;
+    char **h_aliases;
+    int    h_addrtype;
+    int    h_length;
+    char **h_addr_list;
+};
+.EE
+.in
+.P
+These functions replace the
+.BR gethostbyname (3)
+and
+.BR gethostbyaddr (3)
+functions, which could access only the IPv4 network address family.
+The
+.BR getipnodebyname ()
+and
+.BR getipnodebyaddr ()
+functions can access multiple network address families.
+.P
+Unlike the
+.B gethostby
+functions,
+these functions return pointers to dynamically allocated memory.
+The
+.BR freehostent ()
+function is used to release the dynamically allocated memory
+after the caller no longer needs the
+.I hostent
+structure.
+.SS getipnodebyname() arguments
+The
+.BR getipnodebyname ()
+function
+looks up network addresses for the host
+specified by the
+.I name
+argument.
+The
+.I af
+argument specifies one of the following values:
+.TP
+.B AF_INET
+The
+.I name
+argument points to a dotted-quad IPv4 address or a name
+of an IPv4 network host.
+.TP
+.B AF_INET6
+The
+.I name
+argument points to a hexadecimal IPv6 address or a name
+of an IPv6 network host.
+.P
+The
+.I flags
+argument specifies additional options.
+More than one option can be specified by bitwise OR-ing
+them together.
+.I flags
+should be set to 0
+if no options are desired.
+.TP
+.B AI_V4MAPPED
+This flag is used with
+.B AF_INET6
+to request a query for IPv4 addresses instead of
+IPv6 addresses; the IPv4 addresses will
+be mapped to IPv6 addresses.
+.TP
+.B AI_ALL
+This flag is used with
+.B AI_V4MAPPED
+to request a query for both IPv4 and IPv6 addresses.
+Any IPv4 address found will be mapped to an IPv6 address.
+.TP
+.B AI_ADDRCONFIG
+This flag is used with
+.B AF_INET6
+to
+further request that queries for IPv6 addresses should not be made unless
+the system has at least one IPv6 address assigned to a network interface,
+and that queries for IPv4 addresses should not be made unless the
+system has at least one IPv4 address assigned to a network interface.
+This flag may be used by itself or with the
+.B AI_V4MAPPED
+flag.
+.TP
+.B AI_DEFAULT
+This flag is equivalent to
+.BR "(AI_ADDRCONFIG | AI_V4MAPPED)" .
+.SS getipnodebyaddr() arguments
+The
+.BR getipnodebyaddr ()
+function
+looks up the name of the host whose
+network address is
+specified by the
+.I addr
+argument.
+The
+.I af
+argument specifies one of the following values:
+.TP
+.B AF_INET
+The
+.I addr
+argument points to a
+.I struct in_addr
+and
+.I len
+must be set to
+.IR "sizeof(struct in_addr)" .
+.TP
+.B AF_INET6
+The
+.I addr
+argument points to a
+.I struct in6_addr
+and
+.I len
+must be set to
+.IR "sizeof(struct in6_addr)" .
+.SH RETURN VALUE
+NULL is returned if an error occurred, and
+.I error_num
+will contain an error code from the following list:
+.TP
+.B HOST_NOT_FOUND
+The hostname or network address was not found.
+.TP
+.B NO_ADDRESS
+The domain name server recognized the network address or name,
+but no answer was returned.
+This can happen if the network host has only IPv4 addresses and
+a request has been made for IPv6 information only, or vice versa.
+.TP
+.B NO_RECOVERY
+The domain name server returned a permanent failure response.
+.TP
+.B TRY_AGAIN
+The domain name server returned a temporary failure response.
+You might have better luck next time.
+.P
+A successful query returns a pointer to a
+.I hostent
+structure that contains the following fields:
+.TP
+.I h_name
+This is the official name of this network host.
+.TP
+.I h_aliases
+This is an array of pointers to unofficial aliases for the same host.
+The array is terminated by a null pointer.
+.TP
+.I h_addrtype
+This is a copy of the
+.I af
+argument to
+.BR getipnodebyname ()
+or
+.BR getipnodebyaddr ().
+.I h_addrtype
+will always be
+.B AF_INET
+if the
+.I af
+argument was
+.BR AF_INET .
+.I h_addrtype
+will always be
+.B AF_INET6
+if the
+.I af
+argument was
+.BR AF_INET6 .
+.TP
+.I h_length
+This field will be set to
+.I sizeof(struct in_addr)
+if
+.I h_addrtype
+is
+.BR AF_INET ,
+and to
+.I sizeof(struct in6_addr)
+if
+.I h_addrtype
+is
+.BR AF_INET6 .
+.TP
+.I h_addr_list
+This is an array of one or more pointers to network address structures for the
+network host.
+The array is terminated by a null pointer.
+.SH STANDARDS
+None.
+.SH HISTORY
+.\" Not in POSIX.1-2001.
+RFC\ 2553.
+.P
+Present in glibc 2.1.91-95, but removed again.
+Several UNIX-like systems support them, but all
+call them deprecated.
+.SH SEE ALSO
+.BR getaddrinfo (3),
+.BR getnameinfo (3),
+.BR inet_ntop (3),
+.BR inet_pton (3)
diff --git a/man/man3/getline.3 b/man/man3/getline.3
new file mode 100644
index 000000000..e9afc06eb
--- /dev/null
+++ b/man/man3/getline.3
@@ -0,0 +1,182 @@
+'\" t
+.\" Copyright (c) 2001 John Levon <moz@compsoc.man.ac.uk>
+.\" Based in part on GNU libc documentation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getline 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getline, getdelim \- delimited string input
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "ssize_t getline(char **restrict " lineptr ", size_t *restrict " n ,
+.BI "                FILE *restrict " stream );
+.BI "ssize_t getdelim(char **restrict " lineptr ", size_t *restrict " n ,
+.BI "                int " delim ", FILE *restrict " stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getline (),
+.BR getdelim ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.BR getline ()
+reads an entire line from \fIstream\fP,
+storing the address of the buffer containing the text into
+.IR *lineptr .
+The buffer is null-terminated and includes the newline character, if
+one was found.
+.P
+If
+.I *lineptr
+is set to NULL before the call, then
+.BR getline ()
+will allocate a buffer for storing the line.
+This buffer should be freed by the user program
+even if
+.BR getline ()
+failed.
+.P
+Alternatively, before calling
+.BR getline (),
+.I *lineptr
+can contain a pointer to a
+.BR malloc (3)\-allocated
+buffer
+.I *n
+bytes in size.
+If the buffer is not large enough to hold the line,
+.BR getline ()
+resizes it with
+.BR realloc (3),
+updating
+.I *lineptr
+and
+.I *n
+as necessary.
+.P
+In either case, on a successful call,
+.I *lineptr
+and
+.I *n
+will be updated to reflect the buffer address and allocated size respectively.
+.P
+.BR getdelim ()
+works like
+.BR getline (),
+except that a line delimiter other than newline can be specified as the
+.I delimiter
+argument.
+As with
+.BR getline (),
+a delimiter character is not added if one was not present
+in the input before end of file was reached.
+.SH RETURN VALUE
+On success,
+.BR getline ()
+and
+.BR getdelim ()
+return the number of characters read, including the delimiter character,
+but not including the terminating null byte (\[aq]\e0\[aq]).
+This value can be used
+to handle embedded null bytes in the line read.
+.P
+Both functions return \-1 on failure to read a line (including end-of-file
+condition).
+In the event of a failure,
+.I errno
+is set to indicate the error.
+.P
+If
+.I *lineptr
+was set to NULL before the call, then the buffer should be freed by the
+user program even on failure.
+.SH ERRORS
+.TP
+.B EINVAL
+Bad arguments
+.RI ( n
+or
+.I lineptr
+is NULL, or
+.I stream
+is not valid).
+.TP
+.B ENOMEM
+Allocation or reallocation of the line buffer failed.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getline (),
+.BR getdelim ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+GNU, POSIX.1-2008.
+.SH EXAMPLES
+.\" SRC BEGIN (getline.c)
+.EX
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    FILE *stream;
+    char *line = NULL;
+    size_t len = 0;
+    ssize_t nread;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    stream = fopen(argv[1], "r");
+    if (stream == NULL) {
+        perror("fopen");
+        exit(EXIT_FAILURE);
+    }
+\&
+    while ((nread = getline(&line, &len, stream)) != \-1) {
+        printf("Retrieved line of length %zd:\en", nread);
+        fwrite(line, nread, 1, stdout);
+    }
+\&
+    free(line);
+    fclose(stream);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR read (2),
+.BR fgets (3),
+.BR fopen (3),
+.BR fread (3),
+.BR scanf (3)
diff --git a/man/man3/getloadavg.3 b/man/man3/getloadavg.3
new file mode 100644
index 000000000..5bbfc716c
--- /dev/null
+++ b/man/man3/getloadavg.3
@@ -0,0 +1,71 @@
+'\" t
+.\" Copyright (c) 1989, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"     @(#)getloadavg.3	8.1 (Berkeley) 6/4/93
+.\"
+.\" 2007-12-08, mtk, Converted from mdoc to man macros
+.\"
+.TH getloadavg 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getloadavg \- get system load averages
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int getloadavg(double " loadavg[] ", int " nelem );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getloadavg ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    In glibc up to and including 2.19:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getloadavg ()
+function returns the number of processes in the system run queue
+averaged over various periods of time.
+Up to
+.I nelem
+samples are retrieved and assigned to successive elements of
+.IR loadavg[] .
+The system imposes a maximum of 3 samples, representing averages
+over the last 1, 5, and 15 minutes, respectively.
+.SH RETURN VALUE
+If the load average was unobtainable, \-1 is returned; otherwise,
+the number of samples actually retrieved is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getloadavg ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+4.3BSD-Reno, Solaris.
+glibc 2.2.
+.SH SEE ALSO
+.BR uptime (1),
+.BR proc (5)
diff --git a/man/man3/getlogin.3 b/man/man3/getlogin.3
new file mode 100644
index 000000000..f27dfb2d6
--- /dev/null
+++ b/man/man3/getlogin.3
@@ -0,0 +1,259 @@
+'\" t
+.\" Copyright 1995  James R. Van Zandt <jrv@vanzandt.mv.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Changed Tue Sep 19 01:49:29 1995, aeb: moved from man2 to man3
+.\"  added ref to /etc/utmp, added BUGS section, etc.
+.\" modified 2003 Walter Harms, aeb - added getlogin_r, note on stdin use
+.TH getlogin 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getlogin, getlogin_r, cuserid \- get username
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B "char *getlogin(void);"
+.BI "int getlogin_r(char " buf [. bufsize "], size_t " bufsize );
+.P
+.B #include <stdio.h>
+.P
+.BI "char *cuserid(char *" string );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getlogin_r ():
+.nf
+.\" Deprecated: _REENTRANT ||
+    _POSIX_C_SOURCE >= 199506L
+.fi
+.P
+.BR cuserid ():
+.nf
+    Since glibc 2.24:
+        (_XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
+            || _GNU_SOURCE
+    Up to and including glibc 2.23:
+        _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+.BR getlogin ()
+returns a pointer to a string containing the name of
+the user logged in on the controlling terminal of the process, or a
+null pointer if this information cannot be determined.
+The string is
+statically allocated and might be overwritten on subsequent calls to
+this function or to
+.BR cuserid ().
+.P
+.BR getlogin_r ()
+returns this same username in the array
+.I buf
+of size
+.IR bufsize .
+.P
+.BR cuserid ()
+returns a pointer to a string containing a username
+associated with the effective user ID of the process.
+If \fIstring\fP
+is not a null pointer, it should be an array that can hold at least
+\fBL_cuserid\fP characters; the string is returned in this array.
+Otherwise, a pointer to a string in a static area is returned.
+This
+string is statically allocated and might be overwritten on subsequent
+calls to this function or to
+.BR getlogin ().
+.P
+The macro \fBL_cuserid\fP is an integer constant that indicates how
+long an array you might need to store a username.
+\fBL_cuserid\fP is declared in \fI<stdio.h>\fP.
+.P
+These functions let your program identify positively the user who is
+running
+.RB ( cuserid ())
+or the user who logged in this session
+.RB ( getlogin ()).
+(These can differ when set-user-ID programs are involved.)
+.P
+For most purposes, it is more useful to use the environment variable
+\fBLOGNAME\fP to find out who the user is.
+This is more flexible
+precisely because the user can set \fBLOGNAME\fP arbitrarily.
+.SH RETURN VALUE
+.BR getlogin ()
+returns a pointer to the username when successful,
+and NULL on failure, with
+.I errno
+set to indicate the error.
+.BR getlogin_r ()
+returns 0 when successful, and nonzero on failure.
+.SH ERRORS
+POSIX specifies:
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENXIO
+The calling process has no controlling terminal.
+.TP
+.B ERANGE
+(getlogin_r)
+The length of the username, including the terminating null byte (\[aq]\e0\[aq]),
+is larger than
+.IR bufsize .
+.P
+Linux/glibc also has:
+.TP
+.B ENOENT
+There was no corresponding entry in the utmp-file.
+.TP
+.B ENOMEM
+Insufficient memory to allocate passwd structure.
+.TP
+.B ENOTTY
+Standard input didn't refer to a terminal.
+(See BUGS.)
+.SH FILES
+.TP
+\fI/etc/passwd\fP
+password database file
+.TP
+\fI/var/run/utmp\fP
+(traditionally \fI/etc/utmp\fP;
+some libc versions used \fI/var/adm/utmp\fP)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getlogin ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:getlogin race:utent
+sig:ALRM timer locale
+T}
+T{
+.na
+.nh
+.BR getlogin_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:utent sig:ALRM timer
+locale
+T}
+T{
+.na
+.nh
+.BR cuserid ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:cuserid/!string locale
+T}
+.TE
+.P
+In the above table,
+.I utent
+in
+.I race:utent
+signifies that if any of the functions
+.BR setutent (3),
+.BR getutent (3),
+or
+.BR endutent (3)
+are used in parallel in different threads of a program,
+then data races could occur.
+.BR getlogin ()
+and
+.BR getlogin_r ()
+call those functions,
+so we use race:utent to remind users.
+.SH VERSIONS
+OpenBSD has
+.BR getlogin ()
+and
+.BR setlogin (),
+and a username
+associated with a session, even if it has no controlling terminal.
+.SH STANDARDS
+.TP
+.BR getlogin ()
+.TQ
+.BR getlogin_r ()
+POSIX.1-2008.
+.TP
+.BR cuserid ()
+None.
+.SH STANDARDS
+.TP
+.BR getlogin ()
+.TQ
+.BR getlogin_r ():
+POSIX.1-2001.
+OpenBSD.
+.TP
+.BR cuserid ()
+System V, POSIX.1-1988.
+Removed in POSIX.1-1990.
+SUSv2.
+Removed in POSIX.1-2001.
+.IP
+System V has a
+.BR cuserid ()
+function which uses the real
+user ID rather than the effective user ID.
+.SH BUGS
+Unfortunately, it is often rather easy to fool
+.BR getlogin ().
+Sometimes it does not work at all, because some program messed up
+the utmp file.
+Often, it gives only the first 8 characters of
+the login name.
+The user currently logged in on the controlling terminal
+of our program need not be the user who started it.
+Avoid
+.BR getlogin ()
+for security-related purposes.
+.P
+Note that glibc does not follow the POSIX specification and uses
+.I stdin
+instead of
+.IR /dev/tty .
+A bug.
+(Other recent systems, like SunOS 5.8 and HP-UX 11.11 and FreeBSD 4.8
+all return the login name also when
+.I stdin
+is redirected.)
+.P
+Nobody knows precisely what
+.BR cuserid ()
+does; avoid it in portable programs.
+Or avoid it altogether: use
+.I getpwuid(geteuid())
+instead, if that is
+what you meant.
+.B Do not use
+.BR cuserid ().
+.SH SEE ALSO
+.BR logname (1),
+.BR geteuid (2),
+.BR getuid (2),
+.BR utmp (5)
diff --git a/man/man3/getlogin_r.3 b/man/man3/getlogin_r.3
new file mode 100644
index 000000000..b6d53bf72
--- /dev/null
+++ b/man/man3/getlogin_r.3
@@ -0,0 +1 @@
+.so man3/getlogin.3
diff --git a/man/man3/getmntent.3 b/man/man3/getmntent.3
new file mode 100644
index 000000000..4f22658ef
--- /dev/null
+++ b/man/man3/getmntent.3
@@ -0,0 +1,265 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 21:46:57 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 961109, 031115, aeb
+.\"
+.TH getmntent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getmntent, setmntent, addmntent, endmntent, hasmntopt,
+getmntent_r \- get filesystem descriptor file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <mntent.h>
+.P
+.BI "FILE *setmntent(const char *" filename ", const char *" type );
+.P
+.BI "struct mntent *getmntent(FILE *" stream );
+.P
+.BI "int addmntent(FILE *restrict " stream ,
+.BI "              const struct mntent *restrict " mnt );
+.P
+.BI "int endmntent(FILE *" streamp );
+.P
+.BI "char *hasmntopt(const struct mntent *" mnt ", const char *" opt );
+.P
+/* GNU extension */
+.B #include <mntent.h>
+.P
+.BI "struct mntent *getmntent_r(FILE *restrict " streamp ,
+.BI "              struct mntent *restrict " mntbuf ,
+.BI "              char " buf "[restrict ." buflen "], int " buflen );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getmntent_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These routines are used to access the filesystem description file
+.I /etc/fstab
+and the mounted filesystem description file
+.IR /etc/mtab .
+.P
+The
+.BR setmntent ()
+function opens the filesystem description file
+.I filename
+and returns a file pointer which can be used by
+.BR getmntent ().
+The argument
+.I type
+is the type of access
+required and can take the same values as the
+.I mode
+argument of
+.BR fopen (3).
+The returned stream should be closed using
+.BR endmntent ()
+rather than
+.BR fclose (3).
+.P
+The
+.BR getmntent ()
+function reads the next line of the filesystem
+description file from
+.I stream
+and returns a pointer to a structure
+containing the broken out fields from a line in the file.
+The pointer
+points to a static area of memory which is overwritten by subsequent
+calls to
+.BR getmntent ().
+.P
+The
+.BR addmntent ()
+function adds the
+.I mntent
+structure
+.I mnt
+to
+the end of the open
+.IR stream .
+.P
+The
+.BR endmntent ()
+function closes the
+.I stream
+associated with the filesystem description file.
+.P
+The
+.BR hasmntopt ()
+function scans the
+.I mnt_opts
+field (see below)
+of the
+.I mntent
+structure
+.I mnt
+for a substring that matches
+.IR opt .
+See
+.I <mntent.h>
+and
+.BR mount (8)
+for valid mount options.
+.P
+The reentrant
+.BR getmntent_r ()
+function is similar to
+.BR getmntent (),
+but stores the
+.I mntent
+structure
+in the provided
+.IR *mntbuf ,
+and stores the strings pointed to by the entries in that structure
+in the provided array
+.I buf
+of size
+.IR buflen .
+.P
+The
+.I mntent
+structure is defined in
+.I <mntent.h>
+as follows:
+.P
+.in +4n
+.EX
+struct mntent {
+    char *mnt_fsname;   /* name of mounted filesystem */
+    char *mnt_dir;      /* filesystem path prefix */
+    char *mnt_type;     /* mount type (see mntent.h) */
+    char *mnt_opts;     /* mount options (see mntent.h) */
+    int   mnt_freq;     /* dump frequency in days */
+    int   mnt_passno;   /* pass number on parallel fsck */
+};
+.EE
+.in
+.P
+Since fields in the mtab and fstab files are separated by whitespace,
+octal escapes are used to represent the characters space (\e040),
+tab (\e011), newline (\e012), and backslash (\e\e) in those files
+when they occur in one of the four strings in a
+.I mntent
+structure.
+The routines
+.BR addmntent ()
+and
+.BR getmntent ()
+will convert
+from string representation to escaped representation and back.
+When converting from escaped representation, the sequence \e134 is
+also converted to a backslash.
+.SH RETURN VALUE
+The
+.BR getmntent ()
+and
+.BR getmntent_r ()
+functions return
+a pointer to the
+.I mntent
+structure or NULL on failure.
+.P
+The
+.BR addmntent ()
+function returns 0 on success and 1 on failure.
+.P
+The
+.BR endmntent ()
+function always returns 1.
+.P
+The
+.BR hasmntopt ()
+function returns the address of the substring if
+a match is found and NULL otherwise.
+.SH FILES
+.TP
+.I /etc/fstab
+filesystem description file
+.TP
+.I /etc/mtab
+mounted filesystem description file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setmntent (),
+.BR endmntent (),
+.BR hasmntopt ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR getmntent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:mntentbuf locale
+T}
+T{
+.na
+.nh
+.BR addmntent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe race:stream locale
+T}
+T{
+.na
+.nh
+.BR getmntent_r ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+The nonreentrant functions are from SunOS 4.1.3.
+A routine
+.BR getmntent_r ()
+was introduced in HP-UX 10, but it returns an
+.IR int .
+The prototype shown above is glibc-only.
+.P
+System V also has a
+.BR getmntent ()
+function but the calling sequence
+differs, and the returned structure is different.
+Under System V
+.I /etc/mnttab
+is used.
+4.4BSD and Digital UNIX have a routine
+.BR \%getmntinfo (),
+a wrapper around the system call
+.BR getfsstat ().
+.SH SEE ALSO
+.BR fopen (3),
+.BR fstab (5),
+.BR mount (8)
diff --git a/man/man3/getmntent_r.3 b/man/man3/getmntent_r.3
new file mode 100644
index 000000000..3c2bb35c9
--- /dev/null
+++ b/man/man3/getmntent_r.3
@@ -0,0 +1 @@
+.so man3/getmntent.3
diff --git a/man/man3/getnameinfo.3 b/man/man3/getnameinfo.3
new file mode 100644
index 000000000..16c202fc4
--- /dev/null
+++ b/man/man3/getnameinfo.3
@@ -0,0 +1,345 @@
+'\" t
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This page is in the public domain.
+.\" %%%LICENSE_END
+.\"
+.\" Almost all details are from RFC 2553.
+.\"
+.\" 2004-12-14, mtk, Added EAI_OVERFLOW error
+.\" 2004-12-14 Fixed description of error return
+.\"
+.TH getnameinfo 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getnameinfo \- address-to-name translation in protocol-independent manner
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <netdb.h>
+.P
+.BI "int getnameinfo(const struct sockaddr *restrict " addr \
+", socklen_t " addrlen ,
+.BI "                char " host "[_Nullable restrict ." hostlen ],
+.BI "                socklen_t " hostlen ,
+.BI "                char " serv "[_Nullable restrict ." servlen ],
+.BI "                socklen_t " servlen ,
+.BI "                int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getnameinfo ():
+.nf
+    Since glibc 2.22:
+        _POSIX_C_SOURCE >= 200112L
+    glibc 2.21 and earlier:
+        _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getnameinfo ()
+function is the inverse of
+.BR getaddrinfo (3):
+it converts a socket address to a corresponding host and service,
+in a protocol-independent manner.
+It combines the functionality of
+.BR gethostbyaddr (3)
+and
+.BR getservbyport (3),
+but unlike those functions,
+.BR getnameinfo ()
+is reentrant and allows programs to eliminate
+IPv4-versus-IPv6 dependencies.
+.P
+The
+.I addr
+argument is a pointer to a generic socket address structure
+(of type
+.I sockaddr_in
+or
+.IR sockaddr_in6 )
+of size
+.I addrlen
+that holds the input IP address and port number.
+The arguments
+.I host
+and
+.I serv
+are pointers to caller-allocated buffers (of size
+.I hostlen
+and
+.I servlen
+respectively) into which
+.BR getnameinfo ()
+places null-terminated strings containing the host and
+service names respectively.
+.P
+The caller can specify that no hostname (or no service name)
+is required by providing a NULL
+.I host
+(or
+.IR serv )
+argument or a zero
+.I hostlen
+(or
+.IR servlen )
+argument.
+However, at least one of hostname or service name
+must be requested.
+.P
+The
+.I flags
+argument modifies the behavior of
+.BR getnameinfo ()
+as follows:
+.TP
+.B NI_NAMEREQD
+If set, then an error is returned if the hostname cannot be determined.
+.TP
+.B NI_DGRAM
+If set, then the service is datagram (UDP) based rather than
+stream (TCP) based.
+This is required for the few ports (512\[en]514)
+that have different services for UDP and TCP.
+.TP
+.B NI_NOFQDN
+If set, return only the hostname part of the fully qualified domain name
+for local hosts.
+.TP
+.B NI_NUMERICHOST
+If set, then the numeric form of the hostname is returned.
+.\" For example, by calling
+.\" .BR inet_ntop ()
+.\" instead of
+.\" .BR gethostbyaddr ().
+(When not set, this will still happen in case the node's name
+cannot be determined.)
+.\" POSIX.1-2001 TC1 has NI_NUMERICSCOPE, but glibc doesn't have it.
+.TP
+.B NI_NUMERICSERV
+If set, then the numeric form of the service address is returned.
+(When not set, this will still happen in case the service's name
+cannot be determined.)
+.SS Extensions to getnameinfo() for Internationalized Domain Names
+Starting with glibc 2.3.4,
+.BR getnameinfo ()
+has been extended to selectively allow
+hostnames to be transparently converted to and from the
+Internationalized Domain Name (IDN) format (see RFC 3490,
+.IR "Internationalizing Domain Names in Applications (IDNA)" ).
+Three new flags are defined:
+.TP
+.B NI_IDN
+If this flag is used, then the name found in the lookup process is
+converted from IDN format to the locale's encoding if necessary.
+ASCII-only names are not affected by the conversion, which
+makes this flag usable in existing programs and environments.
+.TP
+.B NI_IDN_ALLOW_UNASSIGNED
+.TQ
+.B NI_IDN_USE_STD3_ASCII_RULES
+Setting these flags will enable the
+IDNA_ALLOW_UNASSIGNED (allow unassigned Unicode code points) and
+IDNA_USE_STD3_ASCII_RULES (check output to make sure it is a STD3
+conforming hostname)
+flags respectively to be used in the IDNA handling.
+.SH RETURN VALUE
+.\" FIXME glibc defines the following additional errors, some which
+.\" can probably be returned by getnameinfo(); they need to
+.\" be documented.
+.\"
+.\"     #ifdef __USE_GNU
+.\"     #define EAI_INPROGRESS  -100  /* Processing request in progress.  */
+.\"     #define EAI_CANCELED    -101  /* Request canceled.  */
+.\"     #define EAI_NOTCANCELED -102  /* Request not canceled.  */
+.\"     #define EAI_ALLDONE     -103  /* All requests done.  */
+.\"     #define EAI_INTR        -104  /* Interrupted by a signal.  */
+.\"     #define EAI_IDN_ENCODE  -105  /* IDN encoding failed.  */
+.\"     #endif
+On success, 0 is returned, and node and service names, if requested,
+are filled with null-terminated strings, possibly truncated to fit
+the specified buffer lengths.
+On error, one of the following nonzero error codes is returned:
+.TP
+.B EAI_AGAIN
+The name could not be resolved at this time.
+Try again later.
+.TP
+.B EAI_BADFLAGS
+The
+.I flags
+argument has an invalid value.
+.TP
+.B EAI_FAIL
+A nonrecoverable error occurred.
+.TP
+.B EAI_FAMILY
+The address family was not recognized,
+or the address length was invalid for the specified family.
+.TP
+.B EAI_MEMORY
+Out of memory.
+.TP
+.B EAI_NONAME
+The name does not resolve for the supplied arguments.
+.B NI_NAMEREQD
+is set and the host's name cannot be located,
+or neither hostname nor service name were requested.
+.TP
+.B EAI_OVERFLOW
+The buffer pointed to by
+.I host
+or
+.I serv
+was too small.
+.TP
+.B EAI_SYSTEM
+A system error occurred.
+The error code can be found in
+.IR errno .
+.P
+The
+.BR gai_strerror (3)
+function translates these error codes to a human readable string,
+suitable for error reporting.
+.SH FILES
+.I /etc/hosts
+.br
+.I /etc/nsswitch.conf
+.br
+.I /etc/resolv.conf
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getnameinfo ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+RFC\ 2553.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.P
+Before glibc 2.2, the
+.I hostlen
+and
+.I servlen
+arguments were typed as
+.IR size_t .
+.SH NOTES
+In order to assist the programmer in choosing reasonable sizes
+for the supplied buffers,
+.I <netdb.h>
+defines the constants
+.P
+.in +4n
+.EX
+#define NI_MAXHOST      1025
+#define NI_MAXSERV      32
+.EE
+.in
+.P
+Since glibc 2.8,
+these definitions are exposed only if suitable
+feature test macros are defined, namely:
+.BR _GNU_SOURCE ,
+.B _DEFAULT_SOURCE
+(since glibc 2.19),
+or (in glibc versions up to and including 2.19)
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE .
+.P
+The former is the constant
+.B MAXDNAME
+in recent versions of BIND's
+.I <arpa/nameser.h>
+header file.
+The latter is a guess based on the services listed
+in the current Assigned Numbers RFC.
+.SH EXAMPLES
+The following code tries to get the numeric hostname and service name,
+for a given socket address.
+Note that there is no hardcoded reference to
+a particular address family.
+.P
+.in +4n
+.EX
+struct sockaddr *addr;     /* input */
+socklen_t addrlen;         /* input */
+char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
+\&
+if (getnameinfo(addr, addrlen, hbuf, sizeof(hbuf), sbuf,
+            sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV) == 0)
+    printf("host=%s, serv=%s\en", hbuf, sbuf);
+.EE
+.in
+.P
+The following version checks if the socket address has a
+reverse address mapping.
+.P
+.in +4n
+.EX
+struct sockaddr *addr;     /* input */
+socklen_t addrlen;         /* input */
+char hbuf[NI_MAXHOST];
+\&
+if (getnameinfo(addr, addrlen, hbuf, sizeof(hbuf),
+            NULL, 0, NI_NAMEREQD))
+    printf("could not resolve hostname");
+else
+    printf("host=%s\en", hbuf);
+.EE
+.in
+.P
+An example program using
+.BR getnameinfo ()
+can be found in
+.BR getaddrinfo (3).
+.SH SEE ALSO
+.BR accept (2),
+.BR getpeername (2),
+.BR getsockname (2),
+.BR recvfrom (2),
+.BR socket (2),
+.BR getaddrinfo (3),
+.BR gethostbyaddr (3),
+.BR getservbyname (3),
+.BR getservbyport (3),
+.BR inet_ntop (3),
+.BR hosts (5),
+.BR services (5),
+.BR hostname (7),
+.BR named (8)
+.P
+R.\& Gilligan, S.\& Thomson, J.\& Bound and W.\& Stevens,
+.IR "Basic Socket Interface Extensions for IPv6" ,
+RFC\ 2553, March 1999.
+.P
+Tatsuya Jinmei and Atsushi Onoe,
+.IR "An Extension of Format for IPv6 Scoped Addresses" ,
+internet draft, work in progress
+.UR ftp://ftp.ietf.org\:/internet\-drafts\:/draft\-ietf\-ipngwg\-scopedaddr\-format\-02.txt
+.UE .
+.P
+Craig Metz,
+.IR "Protocol Independence Using the Sockets API" ,
+Proceedings of the freenix track:
+2000 USENIX annual technical conference, June 2000
+.ad l
+.UR http://www.usenix.org\:/publications\:/library\:/proceedings\:/usenix2000\:/freenix\:/metzprotocol.html
+.UE .
diff --git a/man/man3/getnetbyaddr.3 b/man/man3/getnetbyaddr.3
new file mode 100644
index 000000000..70f5670dc
--- /dev/null
+++ b/man/man3/getnetbyaddr.3
@@ -0,0 +1 @@
+.so man3/getnetent.3
diff --git a/man/man3/getnetbyaddr_r.3 b/man/man3/getnetbyaddr_r.3
new file mode 100644
index 000000000..316d315b7
--- /dev/null
+++ b/man/man3/getnetbyaddr_r.3
@@ -0,0 +1 @@
+.so man3/getnetent_r.3
diff --git a/man/man3/getnetbyname.3 b/man/man3/getnetbyname.3
new file mode 100644
index 000000000..70f5670dc
--- /dev/null
+++ b/man/man3/getnetbyname.3
@@ -0,0 +1 @@
+.so man3/getnetent.3
diff --git a/man/man3/getnetbyname_r.3 b/man/man3/getnetbyname_r.3
new file mode 100644
index 000000000..316d315b7
--- /dev/null
+++ b/man/man3/getnetbyname_r.3
@@ -0,0 +1 @@
+.so man3/getnetent_r.3
diff --git a/man/man3/getnetent.3 b/man/man3/getnetent.3
new file mode 100644
index 000000000..a2a268994
--- /dev/null
+++ b/man/man3/getnetent.3
@@ -0,0 +1,206 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 21:48:06 1993 by Rik Faith (faith@cs.unc.edu)
+.TH getnetent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getnetent, getnetbyname, getnetbyaddr, setnetent, endnetent \-
+get network entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.B struct netent *getnetent(void);
+.P
+.BI "struct netent *getnetbyname(const char *" name );
+.BI "struct netent *getnetbyaddr(uint32_t " net ", int " type );
+.P
+.BI "void setnetent(int " stayopen );
+.B void endnetent(void);
+.fi
+.SH DESCRIPTION
+The
+.BR getnetent ()
+function reads the next entry from the networks database
+and returns a
+.I netent
+structure containing
+the broken-out fields from the entry.
+A connection is opened to the database if necessary.
+.P
+The
+.BR getnetbyname ()
+function returns a
+.I netent
+structure
+for the entry from the database
+that matches the network
+.IR name .
+.P
+The
+.BR getnetbyaddr ()
+function returns a
+.I netent
+structure
+for the entry from the database
+that matches the network number
+.I net
+of type
+.IR type .
+The
+.I net
+argument must be in host byte order.
+.P
+The
+.BR setnetent ()
+function opens a connection to the database,
+and sets the next entry to the first entry.
+If
+.I stayopen
+is nonzero,
+then the connection to the database
+will not be closed between calls to one of the
+.BR getnet* ()
+functions.
+.P
+The
+.BR endnetent ()
+function closes the connection to the database.
+.P
+The
+.I netent
+structure is defined in
+.I <netdb.h>
+as follows:
+.P
+.in +4n
+.EX
+struct netent {
+    char      *n_name;     /* official network name */
+    char     **n_aliases;  /* alias list */
+    int        n_addrtype; /* net address type */
+    uint32_t   n_net;      /* network number */
+}
+.EE
+.in
+.P
+The members of the
+.I netent
+structure are:
+.TP
+.I n_name
+The official name of the network.
+.TP
+.I n_aliases
+A NULL-terminated list of alternative names for the network.
+.TP
+.I n_addrtype
+The type of the network number; always
+.BR AF_INET .
+.TP
+.I n_net
+The network number in host byte order.
+.SH RETURN VALUE
+The
+.BR getnetent (),
+.BR getnetbyname (),
+and
+.BR getnetbyaddr ()
+functions return a pointer to a
+statically allocated
+.I netent
+structure, or a null pointer if an
+error occurs or the end of the file is reached.
+.SH FILES
+.TP
+.I /etc/networks
+networks database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getnetent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:netent
+race:netentbuf env locale
+T}
+T{
+.na
+.nh
+.BR getnetbyname ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:netbyname
+env locale
+T}
+T{
+.na
+.nh
+.BR getnetbyaddr ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:netbyaddr
+locale
+T}
+T{
+.na
+.nh
+.BR setnetent (),
+.BR endnetent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:netent env
+locale
+T}
+.TE
+.P
+In the above table,
+.I netent
+in
+.I race:netent
+signifies that if any of the functions
+.BR setnetent (),
+.BR getnetent (),
+or
+.BR endnetent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.P
+Before glibc 2.2, the
+.I net
+argument of
+.BR getnetbyaddr ()
+was of type
+.IR long .
+.SH SEE ALSO
+.BR getnetent_r (3),
+.BR getprotoent (3),
+.BR getservent (3)
+.\" .BR networks (5)
+.br
+RFC\ 1101
diff --git a/man/man3/getnetent_r.3 b/man/man3/getnetent_r.3
new file mode 100644
index 000000000..d8f70c3a2
--- /dev/null
+++ b/man/man3/getnetent_r.3
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"	<mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getnetent_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getnetent_r, getnetbyname_r, getnetbyaddr_r \- get
+network entry (reentrant)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.BI "int getnetent_r(struct netent *restrict " result_buf ,
+.BI "                char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                struct netent **restrict " result ,
+.BI "                int *restrict " h_errnop );
+.BI "int getnetbyname_r(const char *restrict " name ,
+.BI "                struct netent *restrict " result_buf ,
+.BI "                char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                struct netent **restrict " result ,
+.BI "                int *restrict " h_errnop );
+.BI "int getnetbyaddr_r(uint32_t " net ", int " type ,
+.BI "                struct netent *restrict " result_buf ,
+.BI "                char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                struct netent **restrict " result ,
+.BI "                int *restrict " h_errnop );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getnetent_r (),
+.BR getnetbyname_r (),
+.BR getnetbyaddr_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getnetent_r (),
+.BR getnetbyname_r (),
+and
+.BR getnetbyaddr_r ()
+functions are the reentrant equivalents of, respectively,
+.BR getnetent (3),
+.BR getnetbyname (3),
+and
+.BR getnetbynumber (3).
+They differ in the way that the
+.I netent
+structure is returned,
+and in the function calling signature and return value.
+This manual page describes just the differences from
+the nonreentrant functions.
+.P
+Instead of returning a pointer to a statically allocated
+.I netent
+structure as the function result,
+these functions copy the structure into the location pointed to by
+.IR result_buf .
+.P
+The
+.I buf
+array is used to store the string fields pointed to by the returned
+.I netent
+structure.
+(The nonreentrant functions allocate these strings in static storage.)
+The size of this array is specified in
+.IR buflen .
+If
+.I buf
+is too small, the call fails with the error
+.BR ERANGE ,
+and the caller must try again with a larger buffer.
+(A buffer of length 1024 bytes should be sufficient for most applications.)
+.\" I can find no information on the required/recommended buffer size;
+.\" the nonreentrant functions use a 1024 byte buffer -- mtk.
+.P
+If the function call successfully obtains a network record, then
+.I *result
+is set pointing to
+.IR result_buf ;
+otherwise,
+.I *result
+is set to NULL.
+.P
+The buffer pointed to by
+.I h_errnop
+is used to return the value that would be stored in the global variable
+.I h_errno
+by the nonreentrant versions of these functions.
+.\" getnetent.3 doesn't document any use of h_errno, but nevertheless
+.\" the nonreentrant functions no seem to set h_errno.
+.SH RETURN VALUE
+On success, these functions return 0.
+On error, they return one of the positive error numbers listed in ERRORS.
+.P
+On error, record not found
+.RB ( getnetbyname_r (),
+.BR getnetbyaddr_r ()),
+or end of input
+.RB ( getnetent_r ())
+.I result
+is set to NULL.
+.SH ERRORS
+.TP
+.B ENOENT
+.RB ( getnetent_r ())
+No more records in database.
+.TP
+.B ERANGE
+.I buf
+is too small.
+Try again with a larger buffer
+(and increased
+.IR buflen ).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getnetent_r (),
+.BR getnetbyname_r (),
+.BR getnetbyaddr_r ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+Functions with similar names exist on some other systems,
+though typically with different calling signatures.
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR getnetent (3),
+.BR networks (5)
diff --git a/man/man3/getnetgrent.3 b/man/man3/getnetgrent.3
new file mode 100644
index 000000000..34268f941
--- /dev/null
+++ b/man/man3/getnetgrent.3
@@ -0,0 +1 @@
+.so man3/setnetgrent.3
diff --git a/man/man3/getnetgrent_r.3 b/man/man3/getnetgrent_r.3
new file mode 100644
index 000000000..34268f941
--- /dev/null
+++ b/man/man3/getnetgrent_r.3
@@ -0,0 +1 @@
+.so man3/setnetgrent.3
diff --git a/man/man3/getopt.3 b/man/man3/getopt.3
new file mode 100644
index 000000000..02d0ea141
--- /dev/null
+++ b/man/man3/getopt.3
@@ -0,0 +1,577 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright 2006-2008, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 19:27:50 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon Aug 30 22:02:34 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\"  longindex is a pointer, has_arg can take 3 values, using consistent
+.\"  names for optstring and longindex, "\n" in formats fixed.  Documenting
+.\"  opterr and getopt_long_only.  Clarified explanations (borrowing heavily
+.\"  from the source code).
+.\" Modified 8 May 1998 by Joseph S. Myers (jsm28@cam.ac.uk)
+.\" Modified 990715, aeb: changed `EOF' into `-1' since that is what POSIX
+.\"  says; moreover, EOF is not defined in <unistd.h>.
+.\" Modified 2002-02-16, joey: added information about nonexistent
+.\"  option character and colon as first option character
+.\" Modified 2004-07-28, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added text to explain how to order both '[-+]' and ':' at
+.\"		the start of optstring
+.\" Modified 2006-12-15, mtk, Added getopt() example program.
+.\"
+.TH getopt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getopt, getopt_long, getopt_long_only,
+optarg, optind, opterr, optopt \- Parse command-line options
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int getopt(int " argc ", char *" argv [],
+.BI "           const char *" optstring );
+.P
+.BI "extern char *" optarg ;
+.BI "extern int " optind ", " opterr ", " optopt ;
+.P
+.B #include <getopt.h>
+.P
+.BI "int getopt_long(int " argc ", char *" argv [],
+.BI "           const char *" optstring ,
+.BI "           const struct option *" longopts ", int *" longindex );
+.BI "int getopt_long_only(int " argc ", char *" argv [],
+.BI "           const char *" optstring ,
+.BI "           const struct option *" longopts ", int *" longindex );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getopt ():
+.nf
+    _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE
+.fi
+.P
+.BR getopt_long (),
+.BR getopt_long_only ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getopt ()
+function parses the command-line arguments.
+Its arguments
+.I argc
+and
+.I argv
+are the argument count and array as passed to the
+.IR main ()
+function on program invocation.
+An element of \fIargv\fP that starts with \[aq]\-\[aq]
+(and is not exactly "\-" or "\-\-")
+is an option element.
+The characters of this element
+(aside from the initial \[aq]\-\[aq]) are option characters.
+If
+.BR getopt ()
+is called repeatedly, it returns successively each of the option characters
+from each of the option elements.
+.P
+The variable
+.I optind
+is the index of the next element to be processed in
+.IR argv .
+The system initializes this value to 1.
+The caller can reset it to 1 to restart scanning of the same
+.IR argv ,
+or when scanning a new argument vector.
+.P
+If
+.BR getopt ()
+finds another option character, it returns that
+character, updating the external variable \fIoptind\fP and a static
+variable \fInextchar\fP so that the next call to
+.BR getopt ()
+can
+resume the scan with the following option character or
+\fIargv\fP-element.
+.P
+If there are no more option characters,
+.BR getopt ()
+returns \-1.
+Then \fIoptind\fP is the index in \fIargv\fP of the first
+\fIargv\fP-element that is not an option.
+.P
+.I optstring
+is a string containing the legitimate option characters.
+A legitimate option character is any visible one byte
+.BR ascii (7)
+character (for which
+.BR isgraph (3)
+would return nonzero) that is not \[aq]\-\[aq], \[aq]:\[aq], or \[aq];\[aq].
+If such a
+character is followed by a colon, the option requires an argument, so
+.BR getopt ()
+places a pointer to the following text in the same
+\fIargv\fP-element, or the text of the following \fIargv\fP-element, in
+.IR optarg .
+Two colons mean an option takes
+an optional arg; if there is text in the current \fIargv\fP-element
+(i.e., in the same word as the option name itself, for example, "\-oarg"),
+then it is returned in \fIoptarg\fP, otherwise \fIoptarg\fP is set to zero.
+This is a GNU extension.
+If
+.I optstring
+contains
+.B W
+followed by a semicolon, then
+.B \-W foo
+is treated as the long option
+.BR \-\-foo .
+(The
+.B \-W
+option is reserved by POSIX.2 for implementation extensions.)
+This behavior is a GNU extension, not available with libraries before
+glibc 2.
+.P
+By default,
+.BR getopt ()
+permutes the contents of \fIargv\fP as it
+scans, so that eventually all the nonoptions are at the end.
+Two other scanning modes are also implemented.
+If the first character of
+\fIoptstring\fP is \[aq]+\[aq] or the environment variable
+.B POSIXLY_CORRECT
+is set, then option processing stops as soon as a nonoption argument is
+encountered.
+If \[aq]+\[aq] is not the first character of
+.IR optstring ,
+it is treated as a normal option.
+If
+.B POSIXLY_CORRECT
+behaviour is required in this case
+.I optstring
+will contain two \[aq]+\[aq] symbols.
+If the first character of \fIoptstring\fP is \[aq]\-\[aq], then
+each nonoption \fIargv\fP-element is handled as if it were the argument of
+an option with character code 1.
+(This is used by programs that were
+written to expect options and other \fIargv\fP-elements in any order
+and that care about the ordering of the two.)
+The special argument "\-\-" forces an end of option-scanning regardless
+of the scanning mode.
+.P
+While processing the option list,
+.BR getopt ()
+can detect two kinds of errors:
+(1) an option character that was not specified in
+.I optstring
+and (2) a missing option argument
+(i.e., an option at the end of the command line without an expected argument).
+Such errors are handled and reported as follows:
+.IP \[bu] 3
+By default,
+.BR getopt ()
+prints an error message on standard error,
+places the erroneous option character in
+.IR optopt ,
+and returns \[aq]?\[aq] as the function result.
+.IP \[bu]
+If the caller has set the global variable
+.I opterr
+to zero, then
+.BR getopt ()
+does not print an error message.
+The caller can determine that there was an error by testing whether
+the function return value is \[aq]?\[aq].
+(By default,
+.I opterr
+has a nonzero value.)
+.IP \[bu]
+If the first character
+(following any optional \[aq]+\[aq] or \[aq]\-\[aq] described above)
+of \fIoptstring\fP
+is a colon (\[aq]:\[aq]), then
+.BR getopt ()
+likewise does not print an error message.
+In addition, it returns \[aq]:\[aq] instead of \[aq]?\[aq] to
+indicate a missing option argument.
+This allows the caller to distinguish the two different types of errors.
+.\"
+.SS getopt_long() and getopt_long_only()
+The
+.BR getopt_long ()
+function works like
+.BR getopt ()
+except that it also accepts long options, started with two dashes.
+(If the program accepts only long options, then
+.I optstring
+should be specified as an empty string (""), not NULL.)
+Long option names may be abbreviated if the abbreviation is
+unique or is an exact match for some defined option.
+A long option
+may take a parameter, of the form
+.B \-\-arg=param
+or
+.BR "\-\-arg param" .
+.P
+.I longopts
+is a pointer to the first element of an array of
+.I struct option
+declared in
+.I <getopt.h>
+as
+.P
+.in +4n
+.EX
+struct option {
+    const char *name;
+    int         has_arg;
+    int        *flag;
+    int         val;
+};
+.EE
+.in
+.P
+The meanings of the different fields are:
+.TP
+.I name
+is the name of the long option.
+.TP
+.I has_arg
+is:
+\fBno_argument\fP (or 0) if the option does not take an argument;
+\fBrequired_argument\fP (or 1) if the option requires an argument; or
+\fBoptional_argument\fP (or 2) if the option takes an optional argument.
+.TP
+.I flag
+specifies how results are returned for a long option.
+If \fIflag\fP
+is NULL, then
+.BR getopt_long ()
+returns \fIval\fP.
+(For example, the calling program may set \fIval\fP to the equivalent short
+option character.)
+Otherwise,
+.BR getopt_long ()
+returns 0, and
+\fIflag\fP points to a variable which is set to \fIval\fP if the
+option is found, but left unchanged if the option is not found.
+.TP
+\fIval\fP
+is the value to return, or to load into the variable pointed
+to by \fIflag\fP.
+.P
+The last element of the array has to be filled with zeros.
+.P
+If \fIlongindex\fP is not NULL, it
+points to a variable which is set to the index of the long option relative to
+.IR longopts .
+.P
+.BR getopt_long_only ()
+is like
+.BR getopt_long (),
+but \[aq]\-\[aq] as well
+as "\-\-" can indicate a long option.
+If an option that starts with \[aq]\-\[aq]
+(not "\-\-") doesn't match a long option, but does match a short option,
+it is parsed as a short option instead.
+.SH RETURN VALUE
+If an option was successfully found, then
+.BR getopt ()
+returns the option character.
+If all command-line options have been parsed, then
+.BR getopt ()
+returns \-1.
+If
+.BR getopt ()
+encounters an option character that was not in
+.IR optstring ,
+then \[aq]?\[aq] is returned.
+If
+.BR getopt ()
+encounters an option with a missing argument,
+then the return value depends on the first character in
+.IR optstring :
+if it is \[aq]:\[aq], then \[aq]:\[aq] is returned;
+otherwise \[aq]?\[aq] is returned.
+.P
+.BR getopt_long ()
+and
+.BR getopt_long_only ()
+also return the option
+character when a short option is recognized.
+For a long option, they
+return \fIval\fP if \fIflag\fP is NULL, and 0 otherwise.
+Error and \-1 returns are the same as for
+.BR getopt (),
+plus \[aq]?\[aq] for an
+ambiguous match or an extraneous parameter.
+.SH ENVIRONMENT
+.TP
+.B POSIXLY_CORRECT
+If this is set, then option processing stops as soon as a nonoption
+argument is encountered.
+.TP
+.B _<PID>_GNU_nonoption_argv_flags_
+This variable was used by
+.BR bash (1)
+2.0 to communicate to glibc which arguments are the results of
+wildcard expansion and so should not be considered as options.
+This behavior was removed in
+.BR bash (1)
+2.01, but the support remains in glibc.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getopt (),
+.BR getopt_long (),
+.BR getopt_long_only ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:getopt env
+T}
+.TE
+.SH VERSIONS
+POSIX specifies that the
+.I argv
+array argument should be
+.IR const ,
+but these functions permute its elements
+unless the environment variable
+.B POSIXLY_CORRECT
+is set.
+.I const
+is used in the actual prototype to be compatible with other systems;
+however, this page doesn't show the qualifier,
+to avoid confusing readers.
+.SH STANDARDS
+.TP
+.BR getopt ()
+POSIX.1-2008.
+.TP
+.BR getopt_long ()
+.TQ
+.BR getopt_long_only ()
+GNU.
+.IP
+The use of \[aq]+\[aq] and \[aq]\-\[aq] in
+.I optstring
+is a GNU extension.
+.SH HISTORY
+.TP
+.BR getopt ()
+POSIX.1-2001, and POSIX.2.
+.P
+On some older implementations,
+.BR getopt ()
+was declared in
+.IR <stdio.h> .
+SUSv1 permitted the declaration to appear in either
+.I <unistd.h>
+or
+.IR <stdio.h> .
+POSIX.1-1996 marked the use of
+.I <stdio.h>
+for this purpose as LEGACY.
+POSIX.1-2001 does not require the declaration to appear in
+.IR <stdio.h> .
+.SH NOTES
+A program that scans multiple argument vectors,
+or rescans the same vector more than once,
+and wants to make use of GNU extensions such as \[aq]+\[aq]
+and \[aq]\-\[aq] at the start of
+.IR optstring ,
+or changes the value of
+.B POSIXLY_CORRECT
+between scans,
+must reinitialize
+.BR getopt ()
+by resetting
+.I optind
+to 0, rather than the traditional value of 1.
+(Resetting to 0 forces the invocation of an internal initialization
+routine that rechecks
+.B POSIXLY_CORRECT
+and checks for GNU extensions in
+.IR optstring .)
+.P
+Command-line arguments are parsed in strict order
+meaning that an option requiring an argument will consume the next argument,
+regardless of whether that argument is the correctly specified option argument
+or simply the next option
+(in the scenario the user mis-specifies the command line).
+For example, if
+.I optstring
+is specified as "1n:"
+and the user specifies the command line arguments incorrectly as
+.IR "prog\ \-n\ \-1" ,
+the
+.I \-n
+option will be given the
+.B optarg
+value "\-1", and the
+.I \-1
+option will be considered to have not been specified.
+.SH EXAMPLES
+.SS getopt()
+The following trivial example program uses
+.BR getopt ()
+to handle two program options:
+.IR \-n ,
+with no associated value; and
+.IR "\-t val" ,
+which expects an associated value.
+.P
+.\" SRC BEGIN (getopt.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int flags, opt;
+    int nsecs, tfnd;
+\&
+    nsecs = 0;
+    tfnd = 0;
+    flags = 0;
+    while ((opt = getopt(argc, argv, "nt:")) != \-1) {
+        switch (opt) {
+        case \[aq]n\[aq]:
+            flags = 1;
+            break;
+        case \[aq]t\[aq]:
+            nsecs = atoi(optarg);
+            tfnd = 1;
+            break;
+        default: /* \[aq]?\[aq] */
+            fprintf(stderr, "Usage: %s [\-t nsecs] [\-n] name\en",
+                    argv[0]);
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    printf("flags=%d; tfnd=%d; nsecs=%d; optind=%d\en",
+           flags, tfnd, nsecs, optind);
+\&
+    if (optind >= argc) {
+        fprintf(stderr, "Expected argument after options\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("name argument = %s\en", argv[optind]);
+\&
+    /* Other code omitted */
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SS getopt_long()
+The following example program illustrates the use of
+.BR getopt_long ()
+with most of its features.
+.P
+.\" SRC BEGIN (getopt_long.c)
+.EX
+#include <getopt.h>
+#include <stdio.h>     /* for printf */
+#include <stdlib.h>    /* for exit */
+\&
+int
+main(int argc, char *argv[])
+{
+    int c;
+    int digit_optind = 0;
+\&
+    while (1) {
+        int this_option_optind = optind ? optind : 1;
+        int option_index = 0;
+        static struct option long_options[] = {
+            {"add",     required_argument, 0,  0 },
+            {"append",  no_argument,       0,  0 },
+            {"delete",  required_argument, 0,  0 },
+            {"verbose", no_argument,       0,  0 },
+            {"create",  required_argument, 0, \[aq]c\[aq]},
+            {"file",    required_argument, 0,  0 },
+            {0,         0,                 0,  0 }
+        };
+\&
+        c = getopt_long(argc, argv, "abc:d:012",
+                        long_options, &option_index);
+        if (c == \-1)
+            break;
+\&
+        switch (c) {
+        case 0:
+            printf("option %s", long_options[option_index].name);
+            if (optarg)
+                printf(" with arg %s", optarg);
+            printf("\en");
+            break;
+\&
+        case \[aq]0\[aq]:
+        case \[aq]1\[aq]:
+        case \[aq]2\[aq]:
+            if (digit_optind != 0 && digit_optind != this_option_optind)
+              printf("digits occur in two different argv\-elements.\en");
+            digit_optind = this_option_optind;
+            printf("option %c\en", c);
+            break;
+\&
+        case \[aq]a\[aq]:
+            printf("option a\en");
+            break;
+\&
+        case \[aq]b\[aq]:
+            printf("option b\en");
+            break;
+\&
+        case \[aq]c\[aq]:
+            printf("option c with value \[aq]%s\[aq]\en", optarg);
+            break;
+\&
+        case \[aq]d\[aq]:
+            printf("option d with value \[aq]%s\[aq]\en", optarg);
+            break;
+\&
+        case \[aq]?\[aq]:
+            break;
+\&
+        default:
+            printf("?? getopt returned character code 0%o ??\en", c);
+        }
+    }
+\&
+    if (optind < argc) {
+        printf("non\-option ARGV\-elements: ");
+        while (optind < argc)
+            printf("%s ", argv[optind++]);
+        printf("\en");
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getopt (1),
+.BR getsubopt (3)
diff --git a/man/man3/getopt_long.3 b/man/man3/getopt_long.3
new file mode 100644
index 000000000..7612d3f67
--- /dev/null
+++ b/man/man3/getopt_long.3
@@ -0,0 +1 @@
+.so man3/getopt.3
diff --git a/man/man3/getopt_long_only.3 b/man/man3/getopt_long_only.3
new file mode 100644
index 000000000..7612d3f67
--- /dev/null
+++ b/man/man3/getopt_long_only.3
@@ -0,0 +1 @@
+.so man3/getopt.3
diff --git a/man/man3/getpass.3 b/man/man3/getpass.3
new file mode 100644
index 000000000..979da4949
--- /dev/null
+++ b/man/man3/getpass.3
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright (c) 2000 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH getpass 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpass \- get a password
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "[[deprecated]] char *getpass(const char *" prompt );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getpass ():
+.nf
+    Since glibc 2.2.2:
+        _XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE
+    Before glibc 2.2.2:
+        none
+.fi
+.SH DESCRIPTION
+This function is obsolete.
+Do not use it.
+See NOTES.
+If you want to read input without terminal echoing enabled,
+see the description of the
+.I ECHO
+flag in
+.BR termios (3).
+.P
+The
+.BR getpass ()
+function opens
+.I /dev/tty
+(the controlling terminal of the process), outputs the string
+.IR prompt ,
+turns off echoing, reads one line (the "password"),
+restores the terminal state and closes
+.I /dev/tty
+again.
+.SH RETURN VALUE
+The function
+.BR getpass ()
+returns a pointer to a static buffer containing (the first
+.B PASS_MAX
+bytes of) the password without the trailing
+newline, terminated by a null byte (\[aq]\e0\[aq]).
+This buffer may be overwritten by a following call.
+On error, the terminal state is restored,
+.I errno
+is set to indicate the error, and NULL is returned.
+.SH ERRORS
+.TP
+.B ENXIO
+The process does not have a controlling terminal.
+.SH FILES
+.I /dev/tty
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getpass ()
+T}	Thread safety	MT-Unsafe term
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+Version 7 AT&T UNIX.
+Present in SUSv2, but marked LEGACY.
+Removed in POSIX.1-2001.
+.SH NOTES
+.\" For libc4 and libc5, the prompt is not written to
+.\" .I /dev/tty
+.\" but to
+.\" .IR stderr .
+.\" Moreover, if
+.\" .I /dev/tty
+.\" cannot be opened, the password is read from
+.\" .IR stdin .
+.\" The static buffer has length 128 so that only the first 127
+.\" bytes of the password are returned.
+.\" While reading the password, signal generation
+.\" .RB ( SIGINT ,
+.\" .BR SIGQUIT ,
+.\" .BR SIGSTOP ,
+.\" .BR SIGTSTP )
+.\" is disabled and the corresponding characters
+.\" (usually control-C, control-\e, control-Z and control-Y)
+.\" are transmitted as part of the password.
+.\" Since libc 5.4.19 also line editing is disabled, so that also
+.\" backspace and the like will be seen as part of the password.
+You should use instead
+.BR readpassphrase (3bsd),
+provided by
+.IR libbsd .
+.P
+In the GNU C library implementation, if
+.I /dev/tty
+cannot be opened, the prompt is written to
+.I stderr
+and the password is read from
+.IR stdin .
+There is no limit on the length of the password.
+Line editing is not disabled.
+.P
+According to SUSv2, the value of
+.B PASS_MAX
+must be defined in
+.I <limits.h>
+in case it is smaller than 8, and can in any case be obtained using
+.IR sysconf(_SC_PASS_MAX) .
+However, POSIX.2 withdraws the constants
+.B PASS_MAX
+and
+.BR _SC_PASS_MAX ,
+and the function
+.BR getpass ().
+.\" Libc4 and libc5 have never supported
+.\" .B PASS_MAX
+.\" or
+.\" .BR _SC_PASS_MAX .
+The glibc version accepts
+.B _SC_PASS_MAX
+and returns
+.B BUFSIZ
+(e.g., 8192).
+.SH BUGS
+The calling process should zero the password as soon as possible to avoid
+leaving the cleartext password visible in the process's address space.
+.SH SEE ALSO
+.BR crypt (3)
diff --git a/man/man3/getprotobyname.3 b/man/man3/getprotobyname.3
new file mode 100644
index 000000000..f8cb4bba2
--- /dev/null
+++ b/man/man3/getprotobyname.3
@@ -0,0 +1 @@
+.so man3/getprotoent.3
diff --git a/man/man3/getprotobyname_r.3 b/man/man3/getprotobyname_r.3
new file mode 100644
index 000000000..9936ea827
--- /dev/null
+++ b/man/man3/getprotobyname_r.3
@@ -0,0 +1 @@
+.so man3/getprotoent_r.3
diff --git a/man/man3/getprotobynumber.3 b/man/man3/getprotobynumber.3
new file mode 100644
index 000000000..f8cb4bba2
--- /dev/null
+++ b/man/man3/getprotobynumber.3
@@ -0,0 +1 @@
+.so man3/getprotoent.3
diff --git a/man/man3/getprotobynumber_r.3 b/man/man3/getprotobynumber_r.3
new file mode 100644
index 000000000..9936ea827
--- /dev/null
+++ b/man/man3/getprotobynumber_r.3
@@ -0,0 +1 @@
+.so man3/getprotoent_r.3
diff --git a/man/man3/getprotoent.3 b/man/man3/getprotoent.3
new file mode 100644
index 000000000..79b5d23be
--- /dev/null
+++ b/man/man3/getprotoent.3
@@ -0,0 +1,192 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:26:03 1993 by Rik Faith (faith@cs.unc.edu)
+.TH getprotoent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getprotoent, getprotobyname, getprotobynumber, setprotoent,
+endprotoent \- get protocol entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.B struct protoent *getprotoent(void);
+.P
+.BI "struct protoent *getprotobyname(const char *" name );
+.BI "struct protoent *getprotobynumber(int " proto );
+.P
+.BI "void setprotoent(int " stayopen );
+.B void endprotoent(void);
+.fi
+.SH DESCRIPTION
+The
+.BR getprotoent ()
+function reads the next entry from the protocols database (see
+.BR protocols (5))
+and returns a
+.I protoent
+structure
+containing the broken-out fields from the entry.
+A connection is opened to the database if necessary.
+.P
+The
+.BR getprotobyname ()
+function returns a
+.I protoent
+structure
+for the entry from the database
+that matches the protocol name
+.IR name .
+A connection is opened to the database if necessary.
+.P
+The
+.BR getprotobynumber ()
+function returns a
+.I protoent
+structure
+for the entry from the database
+that matches the protocol number
+.IR number .
+A connection is opened to the database if necessary.
+.P
+The
+.BR setprotoent ()
+function opens a connection to the database,
+and sets the next entry to the first entry.
+If
+.I stayopen
+is nonzero,
+then the connection to the database
+will not be closed between calls to one of the
+.BR getproto* ()
+functions.
+.P
+The
+.BR endprotoent ()
+function closes the connection to the database.
+.P
+The
+.I protoent
+structure is defined in
+.I <netdb.h>
+as follows:
+.P
+.in +4n
+.EX
+struct protoent {
+    char  *p_name;       /* official protocol name */
+    char **p_aliases;    /* alias list */
+    int    p_proto;      /* protocol number */
+}
+.EE
+.in
+.P
+The members of the
+.I protoent
+structure are:
+.TP
+.I p_name
+The official name of the protocol.
+.TP
+.I p_aliases
+A NULL-terminated list of alternative names for the protocol.
+.TP
+.I p_proto
+The protocol number.
+.SH RETURN VALUE
+The
+.BR getprotoent (),
+.BR getprotobyname (),
+and
+.BR getprotobynumber ()
+functions return a pointer to a
+statically allocated
+.I protoent
+structure, or a null pointer if an
+error occurs or the end of the file is reached.
+.SH FILES
+.PD 0
+.TP
+.I /etc/protocols
+protocol database file
+.PD
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getprotoent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:protoent
+race:protoentbuf locale
+T}
+T{
+.na
+.nh
+.BR getprotobyname ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:protobyname
+locale
+T}
+T{
+.na
+.nh
+.BR getprotobynumber ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:protobynumber
+locale
+T}
+T{
+.na
+.nh
+.BR setprotoent (),
+.BR endprotoent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:protoent
+locale
+T}
+.TE
+.P
+In the above table,
+.I protoent
+in
+.I race:protoent
+signifies that if any of the functions
+.BR setprotoent (),
+.BR getprotoent (),
+or
+.BR endprotoent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.SH SEE ALSO
+.BR getnetent (3),
+.BR getprotoent_r (3),
+.BR getservent (3),
+.BR protocols (5)
diff --git a/man/man3/getprotoent_r.3 b/man/man3/getprotoent_r.3
new file mode 100644
index 000000000..846eec936
--- /dev/null
+++ b/man/man3/getprotoent_r.3
@@ -0,0 +1,243 @@
+'\" t
+.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"	<mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getprotoent_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getprotoent_r, getprotobyname_r, getprotobynumber_r \- get
+protocol entry (reentrant)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.BI "int getprotoent_r(struct protoent *restrict " result_buf ,
+.BI "                  char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                  struct protoent **restrict " result );
+.BI "int getprotobyname_r(const char *restrict " name ,
+.BI "                  struct protoent *restrict " result_buf ,
+.BI "                  char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                  struct protoent **restrict " result );
+.BI "int getprotobynumber_r(int " proto ,
+.BI "                  struct protoent *restrict " result_buf ,
+.BI "                  char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                  struct protoent **restrict " result );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getprotoent_r (),
+.BR getprotobyname_r (),
+.BR getprotobynumber_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getprotoent_r (),
+.BR getprotobyname_r (),
+and
+.BR getprotobynumber_r ()
+functions are the reentrant equivalents of, respectively,
+.BR getprotoent (3),
+.BR getprotobyname (3),
+and
+.BR getprotobynumber (3).
+They differ in the way that the
+.I protoent
+structure is returned,
+and in the function calling signature and return value.
+This manual page describes just the differences from
+the nonreentrant functions.
+.P
+Instead of returning a pointer to a statically allocated
+.I protoent
+structure as the function result,
+these functions copy the structure into the location pointed to by
+.IR result_buf .
+.P
+The
+.I buf
+array is used to store the string fields pointed to by the returned
+.I protoent
+structure.
+(The nonreentrant functions allocate these strings in static storage.)
+The size of this array is specified in
+.IR buflen .
+If
+.I buf
+is too small, the call fails with the error
+.BR ERANGE ,
+and the caller must try again with a larger buffer.
+(A buffer of length 1024 bytes should be sufficient for most applications.)
+.\" I can find no information on the required/recommended buffer size;
+.\" the nonreentrant functions use a 1024 byte buffer.
+.\" The 1024 byte value is also what the Solaris man page suggests. -- mtk
+.P
+If the function call successfully obtains a protocol record, then
+.I *result
+is set pointing to
+.IR result_buf ;
+otherwise,
+.I *result
+is set to NULL.
+.SH RETURN VALUE
+On success, these functions return 0.
+On error, they return one of the positive error numbers listed in ERRORS.
+.P
+On error, record not found
+.RB ( getprotobyname_r (),
+.BR getprotobynumber_r ()),
+or end of input
+.RB ( getprotoent_r ())
+.I result
+is set to NULL.
+.SH ERRORS
+.TP
+.B ENOENT
+.RB ( getprotoent_r ())
+No more records in database.
+.TP
+.B ERANGE
+.I buf
+is too small.
+Try again with a larger buffer
+(and increased
+.IR buflen ).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getprotoent_r (),
+.BR getprotobyname_r (),
+.BR getprotobynumber_r ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+Functions with similar names exist on some other systems,
+though typically with different calling signatures.
+.SH STANDARDS
+GNU.
+.SH EXAMPLES
+The program below uses
+.BR getprotobyname_r ()
+to retrieve the protocol record for the protocol named
+in its first command-line argument.
+If a second (integer) command-line argument is supplied,
+it is used as the initial value for
+.IR buflen ;
+if
+.BR getprotobyname_r ()
+fails with the error
+.BR ERANGE ,
+the program retries with larger buffer sizes.
+The following shell session shows a couple of sample runs:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out tcp 1"
+ERANGE! Retrying with larger buffer
+getprotobyname_r() returned: 0 (success)  (buflen=78)
+p_name=tcp; p_proto=6; aliases=TCP
+.RB "$" " ./a.out xxx 1"
+ERANGE! Retrying with larger buffer
+getprotobyname_r() returned: 0 (success)  (buflen=100)
+Call failed/record not found
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (getprotoent_r.c)
+.EX
+#define _GNU_SOURCE
+#include <ctype.h>
+#include <errno.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define MAX_BUF 10000
+\&
+int
+main(int argc, char *argv[])
+{
+    int buflen, erange_cnt, s;
+    struct protoent result_buf;
+    struct protoent *result;
+    char buf[MAX_BUF];
+\&
+    if (argc < 2) {
+        printf("Usage: %s proto\-name [buflen]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    buflen = 1024;
+    if (argc > 2)
+        buflen = atoi(argv[2]);
+\&
+    if (buflen > MAX_BUF) {
+        printf("Exceeded buffer limit (%d)\en", MAX_BUF);
+        exit(EXIT_FAILURE);
+    }
+\&
+    erange_cnt = 0;
+    do {
+        s = getprotobyname_r(argv[1], &result_buf,
+                             buf, buflen, &result);
+        if (s == ERANGE) {
+            if (erange_cnt == 0)
+                printf("ERANGE! Retrying with larger buffer\en");
+            erange_cnt++;
+\&
+            /* Increment a byte at a time so we can see exactly
+               what size buffer was required. */
+\&
+            buflen++;
+\&
+            if (buflen > MAX_BUF) {
+                printf("Exceeded buffer limit (%d)\en", MAX_BUF);
+                exit(EXIT_FAILURE);
+            }
+        }
+    } while (s == ERANGE);
+\&
+    printf("getprotobyname_r() returned: %s  (buflen=%d)\en",
+           (s == 0) ? "0 (success)" : (s == ENOENT) ? "ENOENT" :
+           strerror(s), buflen);
+\&
+    if (s != 0 || result == NULL) {
+        printf("Call failed/record not found\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("p_name=%s; p_proto=%d; aliases=",
+           result_buf.p_name, result_buf.p_proto);
+    for (char **p = result_buf.p_aliases; *p != NULL; p++)
+        printf("%s ", *p);
+    printf("\en");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getprotoent (3),
+.BR protocols (5)
diff --git a/man/man3/getpt.3 b/man/man3/getpt.3
new file mode 100644
index 000000000..fca62693e
--- /dev/null
+++ b/man/man3/getpt.3
@@ -0,0 +1,74 @@
+'\" t
+.\" This man page was written by Jeremy Phelps <jphelps@notreached.net>.
+.\"
+.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE)
+.\" Redistribute and modify at will.
+.\" %%%LICENSE_END
+.\"
+.TH getpt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpt \- open a new pseudoterminal master
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <stdlib.h>
+.P
+.B "int getpt(void);"
+.fi
+.SH DESCRIPTION
+.BR getpt ()
+opens a new pseudoterminal device and returns a file descriptor
+that refers to that device.
+It is equivalent to opening the pseudoterminal multiplexor device
+.P
+.in +4n
+.EX
+open("/dev/ptmx", O_RDWR);
+.EE
+.in
+.P
+on Linux systems, though the pseudoterminal multiplexor device is located
+elsewhere on some systems that use the GNU C library.
+.SH RETURN VALUE
+.BR getpt ()
+returns an open file descriptor upon successful completion.
+Otherwise, it
+returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.BR getpt ()
+can fail with various errors described in
+.BR open (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getpt ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Use
+.BR posix_openpt (3)
+instead.
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.SH SEE ALSO
+.BR grantpt (3),
+.BR posix_openpt (3),
+.BR ptsname (3),
+.BR unlockpt (3),
+.BR ptmx (4),
+.BR pty (7)
diff --git a/man/man3/getpw.3 b/man/man3/getpw.3
new file mode 100644
index 000000000..b40b36ffd
--- /dev/null
+++ b/man/man3/getpw.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:23:25 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon May 27 21:37:47 1996 by Martin Schulze (joey@linux.de)
+.\"
+.TH getpw 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpw \- reconstruct password line entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <sys/types.h>
+.B #include <pwd.h>
+.P
+.BI "[[deprecated]] int getpw(uid_t " uid ", char *" buf );
+.fi
+.SH DESCRIPTION
+The
+.BR getpw ()
+function reconstructs the password line entry for
+the given user ID \fIuid\fP in the buffer \fIbuf\fP.
+The returned buffer contains a line of format
+.P
+.in +4n
+.EX
+.B name:passwd:uid:gid:gecos:dir:shell
+.EE
+.in
+.P
+The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct passwd {
+    char   *pw_name;       /* username */
+    char   *pw_passwd;     /* user password */
+    uid_t   pw_uid;        /* user ID */
+    gid_t   pw_gid;        /* group ID */
+    char   *pw_gecos;      /* user information */
+    char   *pw_dir;        /* home directory */
+    char   *pw_shell;      /* shell program */
+};
+.EE
+.in
+.P
+For more information about the fields of this structure, see
+.BR passwd (5).
+.SH RETURN VALUE
+The
+.BR getpw ()
+function returns 0 on success; on error, it returns \-1, and
+.I errno
+is set to indicate the error.
+.P
+If
+.I uid
+is not found in the password database,
+.BR getpw ()
+returns \-1, sets
+.I errno
+to 0, and leaves
+.I buf
+unchanged.
+.SH ERRORS
+.TP
+.BR 0 " or " ENOENT
+No user corresponding to
+.IR uid .
+.TP
+.B EINVAL
+.I buf
+is NULL.
+.TP
+.B ENOMEM
+Insufficient memory to allocate
+.I passwd
+structure.
+.SH FILES
+.TP
+.I /etc/passwd
+password database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getpw ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr2.
+.SH BUGS
+The
+.BR getpw ()
+function is dangerous as it may overflow the provided buffer
+.IR buf .
+It is obsoleted by
+.BR getpwuid (3).
+.SH SEE ALSO
+.BR endpwent (3),
+.BR fgetpwent (3),
+.BR getpwent (3),
+.BR getpwnam (3),
+.BR getpwuid (3),
+.BR putpwent (3),
+.BR setpwent (3),
+.BR passwd (5)
diff --git a/man/man3/getpwent.3 b/man/man3/getpwent.3
new file mode 100644
index 000000000..5c213db9a
--- /dev/null
+++ b/man/man3/getpwent.3
@@ -0,0 +1,191 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified Sat Jul 24 19:22:14 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon May 27 21:37:47 1996 by Martin Schulze (joey@linux.de)
+.\"
+.TH getpwent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpwent, setpwent, endpwent \- get password file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <pwd.h>
+.P
+.B struct passwd *getpwent(void);
+.B void setpwent(void);
+.B void endpwent(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getpwent (),
+.BR setpwent (),
+.BR endpwent ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getpwent ()
+function returns a pointer to a structure containing
+the broken-out fields of a record from the password database
+(e.g., the local password file
+.IR /etc/passwd ,
+NIS, and LDAP).
+The first time
+.BR getpwent ()
+is called, it returns the first entry; thereafter, it returns successive
+entries.
+.P
+The
+.BR setpwent ()
+function rewinds to the beginning
+of the password database.
+.P
+The
+.BR endpwent ()
+function is used to close the password database
+after all processing has been performed.
+.P
+The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct passwd {
+    char   *pw_name;       /* username */
+    char   *pw_passwd;     /* user password */
+    uid_t   pw_uid;        /* user ID */
+    gid_t   pw_gid;        /* group ID */
+    char   *pw_gecos;      /* user information */
+    char   *pw_dir;        /* home directory */
+    char   *pw_shell;      /* shell program */
+};
+.EE
+.in
+.P
+For more information about the fields of this structure, see
+.BR passwd (5).
+.SH RETURN VALUE
+The
+.BR getpwent ()
+function returns a pointer to a
+.I passwd
+structure, or NULL if
+there are no more entries or an error occurred.
+If an error occurs,
+.I errno
+is set to indicate the error.
+If one wants to check
+.I errno
+after the call, it should be set to zero before the call.
+.P
+The return value may point to a static area, and may be overwritten
+by subsequent calls to
+.BR getpwent (),
+.BR getpwnam (3),
+or
+.BR getpwuid (3).
+(Do not pass the returned pointer to
+.BR free (3).)
+.SH ERRORS
+.TP
+.B EINTR
+A signal was caught; see
+.BR signal (7).
+.TP
+.B EIO
+I/O error.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+.\" not in POSIX
+Insufficient memory to allocate
+.I passwd
+structure.
+.\" to allocate the passwd structure, or to allocate buffers
+.TP
+.B ERANGE
+Insufficient buffer space supplied.
+.SH FILES
+.TP
+.I /etc/passwd
+local password database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getpwent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:pwent
+race:pwentbuf locale
+T}
+T{
+.na
+.nh
+.BR setpwent (),
+.BR endpwent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:pwent locale
+T}
+.TE
+.P
+In the above table,
+.I pwent
+in
+.I race:pwent
+signifies that if any of the functions
+.BR setpwent (),
+.BR getpwent (),
+or
+.BR endpwent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH VERSIONS
+The
+.I pw_gecos
+field is not specified in POSIX, but is present on most implementations.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR fgetpwent (3),
+.BR getpw (3),
+.BR getpwent_r (3),
+.BR getpwnam (3),
+.BR getpwuid (3),
+.BR putpwent (3),
+.BR passwd (5)
diff --git a/man/man3/getpwent_r.3 b/man/man3/getpwent_r.3
new file mode 100644
index 000000000..5433e6ae6
--- /dev/null
+++ b/man/man3/getpwent_r.3
@@ -0,0 +1,227 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH getpwent_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpwent_r, fgetpwent_r \- get passwd file entry reentrantly
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <pwd.h>
+.P
+.BI "int getpwent_r(struct passwd *restrict " pwbuf ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct passwd **restrict " pwbufp );
+.BI "int fgetpwent_r(FILE *restrict " stream \
+", struct passwd *restrict " pwbuf ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct passwd **restrict " pwbufp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getpwent_r (),
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR fgetpwent_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The functions
+.BR getpwent_r ()
+and
+.BR fgetpwent_r ()
+are the reentrant versions of
+.BR getpwent (3)
+and
+.BR fgetpwent (3).
+The former reads the next passwd entry from the stream initialized by
+.BR setpwent (3).
+The latter reads the next passwd entry from
+.IR stream .
+.P
+The \fIpasswd\fP structure is defined in
+.I <pwd.h>
+as follows:
+.P
+.in +4n
+.EX
+struct passwd {
+    char    *pw_name;      /* username */
+    char    *pw_passwd;    /* user password */
+    uid_t    pw_uid;       /* user ID */
+    gid_t    pw_gid;       /* group ID */
+    char    *pw_gecos;     /* user information */
+    char    *pw_dir;       /* home directory */
+    char    *pw_shell;     /* shell program */
+};
+.EE
+.in
+.P
+For more information about the fields of this structure, see
+.BR passwd (5).
+.P
+The nonreentrant functions return a pointer to static storage,
+where this static storage contains further pointers to user
+name, password, gecos field, home directory and shell.
+The reentrant functions described here return all of that in
+caller-provided buffers.
+First of all there is the buffer
+.I pwbuf
+that can hold a \fIstruct passwd\fP.
+And next the buffer
+.I buf
+of size
+.I buflen
+that can hold additional strings.
+The result of these functions, the \fIstruct passwd\fP read from the stream,
+is stored in the provided buffer
+.IR *pwbuf ,
+and a pointer to this \fIstruct passwd\fP is returned in
+.IR *pwbufp .
+.SH RETURN VALUE
+On success, these functions return 0 and
+.I *pwbufp
+is a pointer to the \fIstruct passwd\fP.
+On error, these functions return an error value and
+.I *pwbufp
+is NULL.
+.SH ERRORS
+.TP
+.B ENOENT
+No more entries.
+.TP
+.B ERANGE
+Insufficient buffer space supplied.
+Try again with larger buffer.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getpwent_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:pwent locale
+T}
+T{
+.na
+.nh
+.BR fgetpwent_r ()
+T}	Thread safety	MT-Safe
+.TE
+.P
+In the above table,
+.I pwent
+in
+.I race:pwent
+signifies that if any of the functions
+.BR setpwent (),
+.BR getpwent (),
+.BR endpwent (),
+or
+.BR getpwent_r ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH VERSIONS
+Other systems use the prototype
+.P
+.in +4n
+.EX
+struct passwd *
+getpwent_r(struct passwd *pwd, char *buf, int buflen);
+.EE
+.in
+.P
+or, better,
+.P
+.in +4n
+.EX
+int
+getpwent_r(struct passwd *pwd, char *buf, int buflen,
+           FILE **pw_fp);
+.EE
+.in
+.SH STANDARDS
+None.
+.SH HISTORY
+These functions are done in a style resembling
+the POSIX version of functions like
+.BR getpwnam_r (3).
+.SH NOTES
+The function
+.BR getpwent_r ()
+is not really reentrant since it shares the reading position
+in the stream with all other threads.
+.SH EXAMPLES
+.\" SRC BEGIN (getpwent_r.c)
+.EX
+#define _GNU_SOURCE
+#include <pwd.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#define BUFLEN 4096
+\&
+int
+main(void)
+{
+    struct passwd pw;
+    struct passwd *pwp;
+    char buf[BUFLEN];
+    int i;
+\&
+    setpwent();
+    while (1) {
+        i = getpwent_r(&pw, buf, sizeof(buf), &pwp);
+        if (i)
+            break;
+        printf("%s (%jd)\etHOME %s\etSHELL %s\en", pwp\->pw_name,
+               (intmax_t) pwp\->pw_uid, pwp\->pw_dir, pwp\->pw_shell);
+    }
+    endpwent();
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" perhaps add error checking - should use strerror_r
+.\" #include <errno.h>
+.\" #include <stdlib.h>
+.\"         if (i) {
+.\"               if (i == ENOENT)
+.\"                     break;
+.\"               printf("getpwent_r: %s", strerror(i));
+.\"               exit(EXIT_SUCCESS);
+.\"         }
+.\" SRC END
+.SH SEE ALSO
+.BR fgetpwent (3),
+.BR getpw (3),
+.BR getpwent (3),
+.BR getpwnam (3),
+.BR getpwuid (3),
+.BR putpwent (3),
+.BR passwd (5)
diff --git a/man/man3/getpwnam.3 b/man/man3/getpwnam.3
new file mode 100644
index 000000000..7974fd229
--- /dev/null
+++ b/man/man3/getpwnam.3
@@ -0,0 +1,350 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1996-05-27 by Martin Schulze (joey@linux.de)
+.\" Modified 2003-11-15 by aeb
+.\" 2008-11-07, mtk, Added an example program for getpwnam_r().
+.\"
+.TH getpwnam 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getpwnam, getpwnam_r, getpwuid, getpwuid_r \- get password file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <pwd.h>
+.P
+.BI "struct passwd *getpwnam(const char *" name );
+.BI "struct passwd *getpwuid(uid_t " uid );
+.P
+.BI "int getpwnam_r(const char *restrict " name ", \
+struct passwd *restrict " pwd ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct passwd **restrict " result );
+.BI "int getpwuid_r(uid_t " uid ", struct passwd *restrict " pwd ,
+.BI "               char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "               struct passwd **restrict " result );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getpwnam_r (),
+.BR getpwuid_r ():
+.nf
+    _POSIX_C_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getpwnam ()
+function returns a pointer to a structure containing
+the broken-out fields of the record in the password database
+(e.g., the local password file
+.IR /etc/passwd ,
+NIS, and LDAP)
+that matches the username
+.IR name .
+.P
+The
+.BR getpwuid ()
+function returns a pointer to a structure containing
+the broken-out fields of the record in the password database
+that matches the user ID
+.IR uid .
+.P
+The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct passwd {
+    char   *pw_name;       /* username */
+    char   *pw_passwd;     /* user password */
+    uid_t   pw_uid;        /* user ID */
+    gid_t   pw_gid;        /* group ID */
+    char   *pw_gecos;      /* user information */
+    char   *pw_dir;        /* home directory */
+    char   *pw_shell;      /* shell program */
+};
+.EE
+.in
+.P
+See
+.BR passwd (5)
+for more information about these fields.
+.P
+The
+.BR getpwnam_r ()
+and
+.BR getpwuid_r ()
+functions obtain the same information as
+.BR getpwnam ()
+and
+.BR getpwuid (),
+but store the retrieved
+.I passwd
+structure in the space pointed to by
+.IR pwd .
+The string fields pointed to by the members of the
+.I passwd
+structure are stored in the buffer
+.I buf
+of size
+.IR buflen .
+A pointer to the result (in case of success) or NULL (in case no entry
+was found or an error occurred) is stored in
+.IR *result .
+.P
+The call
+.P
+.in +4n
+.EX
+sysconf(_SC_GETPW_R_SIZE_MAX)
+.EE
+.in
+.P
+returns either \-1, without changing
+.IR errno ,
+or an initial suggested size for
+.IR buf .
+(If this size is too small,
+the call fails with
+.BR ERANGE ,
+in which case the caller can retry with a larger buffer.)
+.SH RETURN VALUE
+The
+.BR getpwnam ()
+and
+.BR getpwuid ()
+functions return a pointer to a
+.I passwd
+structure, or NULL if the matching entry is not found or
+an error occurs.
+If an error occurs,
+.I errno
+is set to indicate the error.
+If one wants to check
+.I errno
+after the call, it should be set to zero before the call.
+.P
+The return value may point to a static area, and may be overwritten
+by subsequent calls to
+.BR getpwent (3),
+.BR getpwnam (),
+or
+.BR getpwuid ().
+(Do not pass the returned pointer to
+.BR free (3).)
+.P
+On success,
+.BR getpwnam_r ()
+and
+.BR getpwuid_r ()
+return zero, and set
+.I *result
+to
+.IR pwd .
+If no matching password record was found,
+these functions return 0 and store NULL in
+.IR *result .
+In case of error, an error number is returned, and NULL is stored in
+.IR *result .
+.SH ERRORS
+.TP
+.BR 0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ..."
+The given
+.I name
+or
+.I uid
+was not found.
+.TP
+.B EINTR
+A signal was caught; see
+.BR signal (7).
+.TP
+.B EIO
+I/O error.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOMEM
+.\" not in POSIX
+Insufficient memory to allocate
+.I passwd
+structure.
+.\" This structure is static, allocated 0 or 1 times. No memory leak. (libc45)
+.TP
+.B ERANGE
+Insufficient buffer space supplied.
+.SH FILES
+.TP
+.I /etc/passwd
+local password database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getpwnam ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:pwnam locale
+T}
+T{
+.na
+.nh
+.BR getpwuid ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:pwuid locale
+T}
+T{
+.na
+.nh
+.BR getpwnam_r (),
+.BR getpwuid_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe locale
+T}
+.TE
+.SH VERSIONS
+The
+.I pw_gecos
+field is not specified in POSIX, but is present on most implementations.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH NOTES
+The formulation given above under "RETURN VALUE" is from POSIX.1-2001.
+It does not call "not found" an error, and hence does not specify what value
+.I errno
+might have in this situation.
+But that makes it impossible to recognize
+errors.
+One might argue that according to POSIX
+.I errno
+should be left unchanged if an entry is not found.
+Experiments on various
+UNIX-like systems show that lots of different values occur in this
+situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM, and probably others.
+.\" more precisely:
+.\" AIX 5.1 - gives ESRCH
+.\" OSF1 4.0g - gives EWOULDBLOCK
+.\" libc, glibc up to glibc 2.6, Irix 6.5 - give ENOENT
+.\" since glibc 2.7 - give 0
+.\" FreeBSD 4.8, OpenBSD 3.2, NetBSD 1.6 - give EPERM
+.\" SunOS 5.8 - gives EBADF
+.\" Tru64 5.1b, HP-UX-11i, SunOS 5.7 - give 0
+.P
+The
+.I pw_dir
+field contains the name of the initial working directory of the user.
+Login programs use the value of this field to initialize the
+.B HOME
+environment variable for the login shell.
+An application that wants to determine its user's home directory
+should inspect the value of
+.B HOME
+(rather than the value
+.IR getpwuid(getuid())\->pw_dir )
+since this allows the user to modify their notion of
+"the home directory" during a login session.
+To determine the (initial) home directory of another user,
+it is necessary to use
+.I getpwnam("username")\->pw_dir
+or similar.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR getpwnam_r ()
+to find the full username and user ID for the username
+supplied as a command-line argument.
+.P
+.\" SRC BEGIN (getpwnam.c)
+.EX
+#include <errno.h>
+#include <pwd.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    struct passwd pwd;
+    struct passwd *result;
+    char *buf;
+    long bufsize;
+    int s;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s username\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
+    if (bufsize == \-1)          /* Value was indeterminate */
+        bufsize = 16384;        /* Should be more than enough */
+\&
+    buf = malloc(bufsize);
+    if (buf == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result);
+    if (result == NULL) {
+        if (s == 0)
+            printf("Not found\en");
+        else {
+            errno = s;
+            perror("getpwnam_r");
+        }
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Name: %s; UID: %jd\en", pwd.pw_gecos,
+           (intmax_t) pwd.pw_uid);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR endpwent (3),
+.BR fgetpwent (3),
+.BR getgrnam (3),
+.BR getpw (3),
+.BR getpwent (3),
+.BR getspnam (3),
+.BR putpwent (3),
+.BR setpwent (3),
+.BR passwd (5)
diff --git a/man/man3/getpwnam_r.3 b/man/man3/getpwnam_r.3
new file mode 100644
index 000000000..e83dcaf7e
--- /dev/null
+++ b/man/man3/getpwnam_r.3
@@ -0,0 +1 @@
+.so man3/getpwnam.3
diff --git a/man/man3/getpwuid.3 b/man/man3/getpwuid.3
new file mode 100644
index 000000000..e83dcaf7e
--- /dev/null
+++ b/man/man3/getpwuid.3
@@ -0,0 +1 @@
+.so man3/getpwnam.3
diff --git a/man/man3/getpwuid_r.3 b/man/man3/getpwuid_r.3
new file mode 100644
index 000000000..e83dcaf7e
--- /dev/null
+++ b/man/man3/getpwuid_r.3
@@ -0,0 +1 @@
+.so man3/getpwnam.3
diff --git a/man/man3/getrpcbyname.3 b/man/man3/getrpcbyname.3
new file mode 100644
index 000000000..923085e2e
--- /dev/null
+++ b/man/man3/getrpcbyname.3
@@ -0,0 +1 @@
+.so man3/getrpcent.3
diff --git a/man/man3/getrpcbyname_r.3 b/man/man3/getrpcbyname_r.3
new file mode 100644
index 000000000..78323ea91
--- /dev/null
+++ b/man/man3/getrpcbyname_r.3
@@ -0,0 +1 @@
+.so man3/getrpcent_r.3
diff --git a/man/man3/getrpcbynumber.3 b/man/man3/getrpcbynumber.3
new file mode 100644
index 000000000..923085e2e
--- /dev/null
+++ b/man/man3/getrpcbynumber.3
@@ -0,0 +1 @@
+.so man3/getrpcent.3
diff --git a/man/man3/getrpcbynumber_r.3 b/man/man3/getrpcbynumber_r.3
new file mode 100644
index 000000000..78323ea91
--- /dev/null
+++ b/man/man3/getrpcbynumber_r.3
@@ -0,0 +1 @@
+.so man3/getrpcent_r.3
diff --git a/man/man3/getrpcent.3 b/man/man3/getrpcent.3
new file mode 100644
index 000000000..ec217b70c
--- /dev/null
+++ b/man/man3/getrpcent.3
@@ -0,0 +1,136 @@
+'\" t
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\"
+.\" %%%LICENSE_START(BSD_ONELINE_CDROM)
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\" %%%LICENSE_END
+.\"
+.\" @(#)getrpcent.3n	2.2 88/08/02 4.0 RPCSRC; from 1.11 88/03/14 SMI
+.TH getrpcent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getrpcent, getrpcbyname, getrpcbynumber, setrpcent, endrpcent \- get
+RPC entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.B struct rpcent *getrpcent(void);
+.P
+.BI "struct rpcent *getrpcbyname(const char *" name );
+.BI "struct rpcent *getrpcbynumber(int " number );
+.P
+.BI "void setrpcent(int " stayopen );
+.B void endrpcent(void);
+.fi
+.SH DESCRIPTION
+The
+.BR getrpcent (),
+.BR getrpcbyname (),
+and
+.BR getrpcbynumber ()
+functions each return a pointer to an object with the
+following structure containing the broken-out
+fields of an entry in the RPC program number data base.
+.P
+.in +4n
+.EX
+struct rpcent {
+    char  *r_name;     /* name of server for this RPC program */
+    char **r_aliases;  /* alias list */
+    long   r_number;   /* RPC program number */
+};
+.EE
+.in
+.P
+The members of this structure are:
+.TP
+.I r_name
+The name of the server for this RPC program.
+.TP
+.I r_aliases
+A NULL-terminated list of alternate names for the RPC program.
+.TP
+.I r_number
+The RPC program number for this service.
+.P
+The
+.BR getrpcent ()
+function reads the next entry from the database.
+A connection is opened to the database if necessary.
+.P
+The
+.BR setrpcent ()
+function opens a connection to the database,
+and sets the next entry to the first entry.
+If
+.I stayopen
+is nonzero,
+then the connection to the database
+will not be closed between calls to one of the
+.BR getrpc* ()
+functions.
+.P
+The
+.BR endrpcent ()
+function closes the connection to the database.
+.P
+The
+.BR getrpcbyname ()
+and
+.BR getrpcbynumber ()
+functions sequentially search from the beginning
+of the file until a matching RPC program name or
+program number is found, or until end-of-file is encountered.
+.SH RETURN VALUE
+On success,
+.BR getrpcent (),
+.BR getrpcbyname (),
+and
+.BR getrpcbynumber ()
+return a pointer to a statically allocated
+.I rpcent
+structure.
+NULL is returned on EOF or error.
+.SH FILES
+.TP
+.I /etc/rpc
+RPC program number database.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getrpcent (),
+.BR getrpcbyname (),
+.BR getrpcbynumber ()
+T}	Thread safety	MT-Unsafe
+T{
+.na
+.nh
+.BR setrpcent (),
+.BR endrpcent ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+BSD, Solaris.
+.SH BUGS
+All information
+is contained in a static area
+so it must be copied if it is
+to be saved.
+.SH SEE ALSO
+.BR getrpcent_r (3),
+.BR rpc (5),
+.BR rpcinfo (8),
+.BR ypserv (8)
diff --git a/man/man3/getrpcent_r.3 b/man/man3/getrpcent_r.3
new file mode 100644
index 000000000..558d0a831
--- /dev/null
+++ b/man/man3/getrpcent_r.3
@@ -0,0 +1,136 @@
+'\" t
+.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"	<mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getrpcent_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getrpcent_r, getrpcbyname_r, getrpcbynumber_r \- get
+RPC entry (reentrant)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.BI "int getrpcent_r(struct rpcent *" result_buf ", char " buf [. buflen ],
+.BI "                size_t " buflen ", struct rpcent **" result );
+.BI "int getrpcbyname_r(const char *" name ,
+.BI "                struct rpcent *" result_buf ", char " buf [. buflen ],
+.BI "                size_t " buflen ", struct rpcent **" result );
+.BI "int getrpcbynumber_r(int " number ,
+.BI "                struct rpcent *" result_buf ", char " buf [. buflen ],
+.BI "                size_t " buflen ", struct rpcent **" result );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getrpcent_r (),
+.BR getrpcbyname_r (),
+.BR getrpcbynumber_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getrpcent_r (),
+.BR getrpcbyname_r (),
+and
+.BR getrpcbynumber_r ()
+functions are the reentrant equivalents of, respectively,
+.BR getrpcent (3),
+.BR getrpcbyname (3),
+and
+.BR getrpcbynumber (3).
+They differ in the way that the
+.I rpcent
+structure is returned,
+and in the function calling signature and return value.
+This manual page describes just the differences from
+the nonreentrant functions.
+.P
+Instead of returning a pointer to a statically allocated
+.I rpcent
+structure as the function result,
+these functions copy the structure into the location pointed to by
+.IR result_buf .
+.P
+The
+.I buf
+array is used to store the string fields pointed to by the returned
+.I rpcent
+structure.
+(The nonreentrant functions allocate these strings in static storage.)
+The size of this array is specified in
+.IR buflen .
+If
+.I buf
+is too small, the call fails with the error
+.BR ERANGE ,
+and the caller must try again with a larger buffer.
+(A buffer of length 1024 bytes should be sufficient for most applications.)
+.\" I can find no information on the required/recommended buffer size;
+.\" the nonreentrant functions use a 1024 byte buffer -- mtk.
+.P
+If the function call successfully obtains an RPC record, then
+.I *result
+is set pointing to
+.IR result_buf ;
+otherwise,
+.I *result
+is set to NULL.
+.SH RETURN VALUE
+On success, these functions return 0.
+On error, they return one of the positive error numbers listed in ERRORS.
+.P
+On error, record not found
+.RB ( getrpcbyname_r (),
+.BR getrpcbynumber_r ()),
+or end of input
+.RB ( getrpcent_r ())
+.I result
+is set to NULL.
+.SH ERRORS
+.TP
+.B ENOENT
+.RB ( getrpcent_r ())
+No more records in database.
+.TP
+.B ERANGE
+.I buf
+is too small.
+Try again with a larger buffer
+(and increased
+.IR buflen ).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getrpcent_r (),
+.BR getrpcbyname_r (),
+.BR getrpcbynumber_r ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+Functions with similar names exist on some other systems,
+though typically with different calling signatures.
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR getrpcent (3),
+.BR rpc (5)
diff --git a/man/man3/getrpcport.3 b/man/man3/getrpcport.3
new file mode 100644
index 000000000..bdc6451b6
--- /dev/null
+++ b/man/man3/getrpcport.3
@@ -0,0 +1,59 @@
+'\" t
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\"
+.\" %%%LICENSE_START(BSD_ONELINE_CDROM)
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\" %%%LICENSE_END
+.\"
+.\" @(#)getrpcport.3r	2.2 88/08/02 4.0 RPCSRC; from 1.12 88/02/26 SMI
+.TH getrpcport 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getrpcport \- get RPC port number
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <rpc/rpc.h>"
+.P
+.BI "int getrpcport(const char *" host ", unsigned long " prognum ,
+.BI "               unsigned long " versnum ", unsigned int " proto );
+.fi
+.SH DESCRIPTION
+.BR getrpcport ()
+returns the port number for version
+.I versnum
+of the RPC program
+.I prognum
+running on
+.I host
+and using protocol
+.IR proto .
+It returns 0 if it cannot contact the portmapper, or if
+.I prognum
+is not registered.
+If
+.I prognum
+is registered but not with version
+.IR versnum ,
+it will still return a port number (for some version of the program)
+indicating that the program is indeed registered.
+The version mismatch will be detected upon the first call to the service.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getrpcport ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+BSD, Solaris.
diff --git a/man/man3/gets.3 b/man/man3/gets.3
new file mode 100644
index 000000000..8ffffaaa6
--- /dev/null
+++ b/man/man3/gets.3
@@ -0,0 +1,107 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 28 11:12:07 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Sep  8 15:48:13 1995 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified 2013-12-31, David Malcolm <dmalcolm@redhat.com>
+.\"     Split gets(3) into its own page; fgetc() et al. move to fgetc(3)
+.TH gets 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gets \- get a string from standard input (DEPRECATED)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "[[deprecated]] char *gets(char *" "s" );
+.fi
+.SH DESCRIPTION
+.IR "Never use this function" .
+.P
+.BR gets ()
+reads a line from
+.I stdin
+into the buffer pointed to by
+.I s
+until either a terminating newline or
+.BR EOF ,
+which it replaces with a null byte (\[aq]\e0\[aq]).
+No check for buffer overrun is performed (see BUGS below).
+.SH RETURN VALUE
+.BR gets ()
+returns
+.I s
+on success, and NULL
+on error or when end of file occurs while no characters have been read.
+However, given the lack of buffer overrun checking, there can be no
+guarantees that the function will even return.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR gets ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.P
+LSB deprecates
+.BR gets ().
+POSIX.1-2008 marks
+.BR gets ()
+obsolescent.
+ISO C11 removes the specification of
+.BR gets ()
+from the C language, and since glibc 2.16,
+glibc header files don't expose the function declaration if the
+.B _ISOC11_SOURCE
+feature test macro is defined.
+.SH BUGS
+Never use
+.BR gets ().
+Because it is impossible to tell without knowing the data in advance how many
+characters
+.BR gets ()
+will read, and because
+.BR gets ()
+will continue to store characters past the end of the buffer,
+it is extremely dangerous to use.
+It has been used to break computer security.
+Use
+.BR fgets ()
+instead.
+.P
+For more information, see CWE-242 (aka "Use of Inherently Dangerous
+Function") at
+http://cwe.mitre.org/data/definitions/242.html
+.SH SEE ALSO
+.BR read (2),
+.BR write (2),
+.BR ferror (3),
+.BR fgetc (3),
+.BR fgets (3),
+.BR fgetwc (3),
+.BR fgetws (3),
+.BR fopen (3),
+.BR fread (3),
+.BR fseek (3),
+.BR getline (3),
+.BR getwchar (3),
+.BR puts (3),
+.BR scanf (3),
+.BR ungetwc (3),
+.BR unlocked_stdio (3),
+.BR feature_test_macros (7)
diff --git a/man/man3/getservbyname.3 b/man/man3/getservbyname.3
new file mode 100644
index 000000000..eaafb1c1e
--- /dev/null
+++ b/man/man3/getservbyname.3
@@ -0,0 +1 @@
+.so man3/getservent.3
diff --git a/man/man3/getservbyname_r.3 b/man/man3/getservbyname_r.3
new file mode 100644
index 000000000..b36a44260
--- /dev/null
+++ b/man/man3/getservbyname_r.3
@@ -0,0 +1 @@
+.so man3/getservent_r.3
diff --git a/man/man3/getservbyport.3 b/man/man3/getservbyport.3
new file mode 100644
index 000000000..eaafb1c1e
--- /dev/null
+++ b/man/man3/getservbyport.3
@@ -0,0 +1 @@
+.so man3/getservent.3
diff --git a/man/man3/getservbyport_r.3 b/man/man3/getservbyport_r.3
new file mode 100644
index 000000000..b36a44260
--- /dev/null
+++ b/man/man3/getservbyport_r.3
@@ -0,0 +1 @@
+.so man3/getservent_r.3
diff --git a/man/man3/getservent.3 b/man/man3/getservent.3
new file mode 100644
index 000000000..97f01dfbb
--- /dev/null
+++ b/man/man3/getservent.3
@@ -0,0 +1,209 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:19:11 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Wed Oct 18 20:23:54 1995 by Martin Schulze <joey@infodrom.north.de>
+.\" Modified Mon Apr 22 01:50:54 1996 by Martin Schulze <joey@infodrom.north.de>
+.\" 2001-07-25 added a clause about NULL proto (Martin Michlmayr or David N. Welton)
+.\"
+.TH getservent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getservent, getservbyname, getservbyport, setservent, endservent \-
+get service entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.B struct servent *getservent(void);
+.P
+.BI "struct servent *getservbyname(const char *" name ", const char *" proto );
+.BI "struct servent *getservbyport(int " port ", const char *" proto );
+.P
+.BI "void setservent(int " stayopen );
+.B void endservent(void);
+.fi
+.SH DESCRIPTION
+The
+.BR getservent ()
+function reads the next entry from the services database (see
+.BR services (5))
+and returns a
+.I servent
+structure containing
+the broken-out fields from the entry.
+A connection is opened to the database if necessary.
+.P
+The
+.BR getservbyname ()
+function returns a
+.I servent
+structure
+for the entry from the database
+that matches the service
+.I name
+using protocol
+.IR proto .
+If
+.I proto
+is NULL, any protocol will be matched.
+A connection is opened to the database if necessary.
+.P
+The
+.BR getservbyport ()
+function returns a
+.I servent
+structure
+for the entry from the database
+that matches the port
+.I port
+(given in network byte order)
+using protocol
+.IR proto .
+If
+.I proto
+is NULL, any protocol will be matched.
+A connection is opened to the database if necessary.
+.P
+The
+.BR setservent ()
+function opens a connection to the database,
+and sets the next entry to the first entry.
+If
+.I stayopen
+is nonzero,
+then the connection to the database
+will not be closed between calls to one of the
+.BR getserv* ()
+functions.
+.P
+The
+.BR endservent ()
+function closes the connection to the database.
+.P
+The
+.I servent
+structure is defined in
+.I <netdb.h>
+as follows:
+.P
+.in +4n
+.EX
+struct servent {
+    char  *s_name;       /* official service name */
+    char **s_aliases;    /* alias list */
+    int    s_port;       /* port number */
+    char  *s_proto;      /* protocol to use */
+}
+.EE
+.in
+.P
+The members of the
+.I servent
+structure are:
+.TP
+.I s_name
+The official name of the service.
+.TP
+.I s_aliases
+A NULL-terminated list of alternative names for the service.
+.TP
+.I s_port
+The port number for the service given in network byte order.
+.TP
+.I s_proto
+The name of the protocol to use with this service.
+.SH RETURN VALUE
+The
+.BR getservent (),
+.BR getservbyname (),
+and
+.BR getservbyport ()
+functions return a pointer to a
+statically allocated
+.I servent
+structure, or NULL if an
+error occurs or the end of the file is reached.
+.SH FILES
+.TP
+.I /etc/services
+services database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getservent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:servent
+race:serventbuf locale
+T}
+T{
+.na
+.nh
+.BR getservbyname ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:servbyname
+locale
+T}
+T{
+.na
+.nh
+.BR getservbyport ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:servbyport
+locale
+T}
+T{
+.na
+.nh
+.BR setservent (),
+.BR endservent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:servent
+locale
+T}
+.TE
+.P
+In the above table,
+.I servent
+in
+.I race:servent
+signifies that if any of the functions
+.BR setservent (),
+.BR getservent (),
+or
+.BR endservent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.SH SEE ALSO
+.BR getnetent (3),
+.BR getprotoent (3),
+.BR getservent_r (3),
+.BR services (5)
diff --git a/man/man3/getservent_r.3 b/man/man3/getservent_r.3
new file mode 100644
index 000000000..50952d87d
--- /dev/null
+++ b/man/man3/getservent_r.3
@@ -0,0 +1,249 @@
+'\" t
+.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"	<mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getservent_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getservent_r, getservbyname_r, getservbyport_r \- get
+service entry (reentrant)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.BI "int getservent_r(struct servent *restrict " result_buf ,
+.BI "                 char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                 struct servent **restrict " result );
+.BI "int getservbyname_r(const char *restrict " name ,
+.BI "                 const char *restrict " proto ,
+.BI "                 struct servent *restrict " result_buf ,
+.BI "                 char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                 struct servent **restrict " result );
+.BI "int getservbyport_r(int " port ,
+.BI "                 const char *restrict " proto ,
+.BI "                 struct servent *restrict " result_buf ,
+.BI "                 char " buf "[restrict ." buflen "], size_t " buflen ,
+.BI "                 struct servent **restrict " result );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getservent_r (),
+.BR getservbyname_r (),
+.BR getservbyport_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR getservent_r (),
+.BR getservbyname_r (),
+and
+.BR getservbyport_r ()
+functions are the reentrant equivalents of, respectively,
+.BR getservent (3),
+.BR getservbyname (3),
+and
+.BR getservbyport (3).
+They differ in the way that the
+.I servent
+structure is returned,
+and in the function calling signature and return value.
+This manual page describes just the differences from
+the nonreentrant functions.
+.P
+Instead of returning a pointer to a statically allocated
+.I servent
+structure as the function result,
+these functions copy the structure into the location pointed to by
+.IR result_buf .
+.P
+The
+.I buf
+array is used to store the string fields pointed to by the returned
+.I servent
+structure.
+(The nonreentrant functions allocate these strings in static storage.)
+The size of this array is specified in
+.IR buflen .
+If
+.I buf
+is too small, the call fails with the error
+.BR ERANGE ,
+and the caller must try again with a larger buffer.
+(A buffer of length 1024 bytes should be sufficient for most applications.)
+.\" I can find no information on the required/recommended buffer size;
+.\" the nonreentrant functions use a 1024 byte buffer -- mtk.
+.P
+If the function call successfully obtains a service record, then
+.I *result
+is set pointing to
+.IR result_buf ;
+otherwise,
+.I *result
+is set to NULL.
+.SH RETURN VALUE
+On success, these functions return 0.
+On error, they return one of the positive error numbers listed in errors.
+.P
+On error, record not found
+.RB ( getservbyname_r (),
+.BR getservbyport_r ()),
+or end of input
+.RB ( getservent_r ())
+.I result
+is set to NULL.
+.SH ERRORS
+.TP
+.B ENOENT
+.RB ( getservent_r ())
+No more records in database.
+.TP
+.B ERANGE
+.I buf
+is too small.
+Try again with a larger buffer
+(and increased
+.IR buflen ).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getservent_r (),
+.BR getservbyname_r (),
+.BR getservbyport_r ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+Functions with similar names exist on some other systems,
+though typically with different calling signatures.
+.SH STANDARDS
+GNU.
+.SH EXAMPLES
+The program below uses
+.BR getservbyport_r ()
+to retrieve the service record for the port and protocol named
+in its first command-line argument.
+If a third (integer) command-line argument is supplied,
+it is used as the initial value for
+.IR buflen ;
+if
+.BR getservbyport_r ()
+fails with the error
+.BR ERANGE ,
+the program retries with larger buffer sizes.
+The following shell session shows a couple of sample runs:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 7 tcp 1"
+ERANGE! Retrying with larger buffer
+getservbyport_r() returned: 0 (success)  (buflen=87)
+s_name=echo; s_proto=tcp; s_port=7; aliases=
+.RB "$" " ./a.out 77777 tcp"
+getservbyport_r() returned: 0 (success)  (buflen=1024)
+Call failed/record not found
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (getservent_r.c)
+.EX
+#define _GNU_SOURCE
+#include <ctype.h>
+#include <errno.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define MAX_BUF 10000
+\&
+int
+main(int argc, char *argv[])
+{
+    int buflen, erange_cnt, port, s;
+    struct servent result_buf;
+    struct servent *result;
+    char buf[MAX_BUF];
+    char *protop;
+\&
+    if (argc < 3) {
+        printf("Usage: %s port\-num proto\-name [buflen]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    port = htons(atoi(argv[1]));
+    protop = (strcmp(argv[2], "null") == 0 ||
+              strcmp(argv[2], "NULL") == 0) ?  NULL : argv[2];
+\&
+    buflen = 1024;
+    if (argc > 3)
+        buflen = atoi(argv[3]);
+\&
+    if (buflen > MAX_BUF) {
+        printf("Exceeded buffer limit (%d)\en", MAX_BUF);
+        exit(EXIT_FAILURE);
+    }
+\&
+    erange_cnt = 0;
+    do {
+        s = getservbyport_r(port, protop, &result_buf,
+                            buf, buflen, &result);
+        if (s == ERANGE) {
+            if (erange_cnt == 0)
+                printf("ERANGE! Retrying with larger buffer\en");
+            erange_cnt++;
+\&
+            /* Increment a byte at a time so we can see exactly
+               what size buffer was required. */
+\&
+            buflen++;
+\&
+            if (buflen > MAX_BUF) {
+                printf("Exceeded buffer limit (%d)\en", MAX_BUF);
+                exit(EXIT_FAILURE);
+            }
+        }
+    } while (s == ERANGE);
+\&
+    printf("getservbyport_r() returned: %s  (buflen=%d)\en",
+           (s == 0) ? "0 (success)" : (s == ENOENT) ? "ENOENT" :
+           strerror(s), buflen);
+\&
+    if (s != 0 || result == NULL) {
+        printf("Call failed/record not found\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("s_name=%s; s_proto=%s; s_port=%d; aliases=",
+           result_buf.s_name, result_buf.s_proto,
+           ntohs(result_buf.s_port));
+    for (char **p = result_buf.s_aliases; *p != NULL; p++)
+        printf("%s ", *p);
+    printf("\en");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getservent (3),
+.BR services (5)
diff --git a/man/man3/getspent.3 b/man/man3/getspent.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/getspent.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/getspent_r.3 b/man/man3/getspent_r.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/getspent_r.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/getspnam.3 b/man/man3/getspnam.3
new file mode 100644
index 000000000..c97f2fa2d
--- /dev/null
+++ b/man/man3/getspnam.3
@@ -0,0 +1,344 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl) and
+.\" Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH getspnam 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getspnam, getspnam_r, getspent, getspent_r, setspent, endspent,
+fgetspent, fgetspent_r, sgetspent, sgetspent_r, putspent,
+lckpwdf, ulckpwdf \- get shadow password file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+/* General shadow password file API */
+.B #include <shadow.h>
+.P
+.BI "struct spwd *getspnam(const char *" name );
+.B struct spwd *getspent(void);
+.P
+.B void setspent(void);
+.B void endspent(void);
+.P
+.BI "struct spwd *fgetspent(FILE *" stream );
+.BI "struct spwd *sgetspent(const char *" s );
+.P
+.BI "int putspent(const struct spwd *" p ", FILE *" stream );
+.P
+.B int lckpwdf(void);
+.B int ulckpwdf(void);
+.P
+/* GNU extension */
+.B #include <shadow.h>
+.P
+.BI "int getspent_r(struct spwd *" spbuf ,
+.BI "               char " buf [. buflen "], size_t " buflen ", \
+struct spwd **" spbufp );
+.BI "int getspnam_r(const char *" name ", struct spwd *" spbuf ,
+.BI "               char " buf [. buflen "], size_t " buflen ", \
+struct spwd **" spbufp );
+.P
+.BI "int fgetspent_r(FILE *" stream ", struct spwd *" spbuf ,
+.BI "               char " buf [. buflen "], size_t " buflen ", \
+struct spwd **" spbufp );
+.BI "int sgetspent_r(const char *" s ", struct spwd *" spbuf ,
+.BI "               char " buf [. buflen "], size_t " buflen ", \
+struct spwd **" spbufp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getspent_r (),
+.BR getspnam_r (),
+.BR fgetspent_r (),
+.BR sgetspent_r ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+Long ago it was considered safe to have encrypted passwords openly
+visible in the password file.
+When computers got faster and people
+got more security-conscious, this was no longer acceptable.
+Julianne Frances Haugh implemented the shadow password suite
+that keeps the encrypted passwords in
+the shadow password database
+(e.g., the local shadow password file
+.IR /etc/shadow ,
+NIS, and LDAP),
+readable only by root.
+.P
+The functions described below resemble those for
+the traditional password database
+(e.g., see
+.BR getpwnam (3)
+and
+.BR getpwent (3)).
+.\" FIXME . I've commented out the following for the
+.\" moment.  The relationship between PAM and nsswitch.conf needs
+.\" to be clearly documented in one place, which is pointed to by
+.\" the pages for the user, group, and shadow password functions.
+.\" (Jul 2005, mtk)
+.\"
+.\" This shadow password setup has been superseded by PAM
+.\" (pluggable authentication modules), and the file
+.\" .I /etc/nsswitch.conf
+.\" now describes the sources to be used.
+.P
+The
+.BR getspnam ()
+function returns a pointer to a structure containing
+the broken-out fields of the record in the shadow password database
+that matches the username
+.IR name .
+.P
+The
+.BR getspent ()
+function returns a pointer to the next entry in the shadow password
+database.
+The position in the input stream is initialized by
+.BR setspent ().
+When done reading, the program may call
+.BR endspent ()
+so that resources can be deallocated.
+.\" some systems require a call of setspent() before the first getspent()
+.\" glibc does not
+.P
+The
+.BR fgetspent ()
+function is similar to
+.BR getspent ()
+but uses the supplied stream instead of the one implicitly opened by
+.BR setspent ().
+.P
+The
+.BR sgetspent ()
+function parses the supplied string
+.I s
+into a struct
+.IR spwd .
+.P
+The
+.BR putspent ()
+function writes the contents of the supplied struct
+.I spwd
+.I *p
+as a text line in the shadow password file format to
+.IR stream .
+String entries with value NULL and numerical entries with value \-1
+are written as an empty string.
+.P
+The
+.BR lckpwdf ()
+function is intended to protect against multiple simultaneous accesses
+of the shadow password database.
+It tries to acquire a lock, and returns 0 on success,
+or \-1 on failure (lock not obtained within 15 seconds).
+The
+.BR ulckpwdf ()
+function releases the lock again.
+Note that there is no protection against direct access of the shadow
+password file.
+Only programs that use
+.BR lckpwdf ()
+will notice the lock.
+.P
+These were the functions that formed the original shadow API.
+They are widely available.
+.\" Also in libc5
+.\" SUN doesn't have sgetspent()
+.SS Reentrant versions
+Analogous to the reentrant functions for the password database, glibc
+also has reentrant functions for the shadow password database.
+The
+.BR getspnam_r ()
+function is like
+.BR getspnam ()
+but stores the retrieved shadow password structure in the space pointed to by
+.IR spbuf .
+This shadow password structure contains pointers to strings, and these strings
+are stored in the buffer
+.I buf
+of size
+.IR buflen .
+A pointer to the result (in case of success) or NULL (in case no entry
+was found or an error occurred) is stored in
+.IR *spbufp .
+.P
+The functions
+.BR getspent_r (),
+.BR fgetspent_r (),
+and
+.BR sgetspent_r ()
+are similarly analogous to their nonreentrant counterparts.
+.P
+Some non-glibc systems also have functions with these names,
+often with different prototypes.
+.\" SUN doesn't have sgetspent_r()
+.SS Structure
+The shadow password structure is defined in \fI<shadow.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct spwd {
+    char *sp_namp;     /* Login name */
+    char *sp_pwdp;     /* Encrypted password */
+    long  sp_lstchg;   /* Date of last change
+                          (measured in days since
+                          1970\-01\-01 00:00:00 +0000 (UTC)) */
+    long  sp_min;      /* Min # of days between changes */
+    long  sp_max;      /* Max # of days between changes */
+    long  sp_warn;     /* # of days before password expires
+                          to warn user to change it */
+    long  sp_inact;    /* # of days after password expires
+                          until account is disabled */
+    long  sp_expire;   /* Date when account expires
+                          (measured in days since
+                          1970\-01\-01 00:00:00 +0000 (UTC)) */
+    unsigned long sp_flag;  /* Reserved */
+};
+.EE
+.in
+.SH RETURN VALUE
+The functions that return a pointer return NULL if no more entries
+are available or if an error occurs during processing.
+The functions which have \fIint\fP as the return value return 0 for
+success and \-1 for failure, with
+.I errno
+set to indicate the error.
+.P
+For the nonreentrant functions, the return value may point to static area,
+and may be overwritten by subsequent calls to these functions.
+.P
+The reentrant functions return zero on success.
+In case of error, an error number is returned.
+.SH ERRORS
+.TP
+.B EACCES
+The caller does not have permission to access the shadow password file.
+.TP
+.B ERANGE
+Supplied buffer is too small.
+.SH FILES
+.TP
+.I /etc/shadow
+local shadow password database file
+.TP
+.I /etc/.pwd.lock
+lock file
+.P
+The include file
+.I <paths.h>
+defines the constant
+.B _PATH_SHADOW
+to the pathname of the shadow password file.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getspnam ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:getspnam locale
+T}
+T{
+.na
+.nh
+.BR getspent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:getspent
+race:spentbuf locale
+T}
+T{
+.na
+.nh
+.BR setspent (),
+.BR endspent (),
+.BR getspent_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:getspent locale
+T}
+T{
+.na
+.nh
+.BR fgetspent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:fgetspent
+T}
+T{
+.na
+.nh
+.BR sgetspent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:sgetspent
+T}
+T{
+.na
+.nh
+.BR putspent (),
+.BR getspnam_r (),
+.BR sgetspent_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe locale
+T}
+T{
+.na
+.nh
+.BR lckpwdf (),
+.BR ulckpwdf (),
+.BR fgetspent_r ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe
+T}
+.TE
+.P
+In the above table,
+.I getspent
+in
+.I race:getspent
+signifies that if any of the functions
+.BR setspent (),
+.BR getspent (),
+.BR getspent_r (),
+or
+.BR endspent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH VERSIONS
+Many other systems provide a similar API.
+.SH STANDARDS
+None.
+.SH SEE ALSO
+.BR getgrnam (3),
+.BR getpwnam (3),
+.BR getpwnam_r (3),
+.BR shadow (5)
diff --git a/man/man3/getspnam_r.3 b/man/man3/getspnam_r.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/getspnam_r.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/getsubopt.3 b/man/man3/getsubopt.3
new file mode 100644
index 000000000..e5da55405
--- /dev/null
+++ b/man/man3/getsubopt.3
@@ -0,0 +1,251 @@
+'\" t
+.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2007 Justin Pryzby <pryzbyj@justinpryzby.com>
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Permission is hereby granted, free of charge, to any person obtaining
+.\" a copy of this software and associated documentation files (the
+.\" "Software"), to deal in the Software without restriction, including
+.\" without limitation the rights to use, copy, modify, merge, publish,
+.\" distribute, sublicense, and/or sell copies of the Software, and to
+.\" permit persons to whom the Software is furnished to do so, subject to
+.\" the following conditions:
+.\"
+.\" The above copyright notice and this permission notice shall be
+.\" included in all copies or substantial portions of the Software.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+.\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+.\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+.\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+.\" %%%LICENSE_END
+.\"
+.TH getsubopt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getsubopt \- parse suboption arguments from a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int getsubopt(char **restrict " optionp ", char *const *restrict " tokens ,
+.BI "              char **restrict " valuep );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getsubopt ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+.fi
+.SH DESCRIPTION
+.BR getsubopt ()
+parses the list of comma-separated suboptions provided in
+.IR optionp .
+(Such a suboption list is typically produced when
+.BR getopt (3)
+is used to parse a command line;
+see for example the \fI\-o\fP option of
+.BR mount (8).)
+Each suboption may include an associated value,
+which is separated from the suboption name by an equal sign.
+The following is an example of the kind of string
+that might be passed in
+.IR optionp :
+.P
+.in +4n
+.EX
+.B ro,name=xyz
+.EE
+.in
+.P
+The
+.I tokens
+argument is a pointer to a NULL-terminated array of pointers to the tokens that
+.BR getsubopt ()
+will look for in
+.IR optionp .
+The tokens should be distinct, null-terminated strings containing at
+least one character, with no embedded equal signs or commas.
+.P
+Each call to
+.BR getsubopt ()
+returns information about the next unprocessed suboption in
+.IR optionp .
+The first equal sign in a suboption (if any) is interpreted as a
+separator between the name and the value of that suboption.
+The value extends to the next comma,
+or (for the last suboption) to the end of the string.
+If the name of the suboption matches a known name from
+.IR tokens ,
+and a value string was found,
+.BR getsubopt ()
+sets
+.I *valuep
+to the address of that string.
+The first comma in
+.I optionp
+is overwritten with a null byte, so
+.I *valuep
+is precisely the "value string" for that suboption.
+.P
+If the suboption is recognized, but no value string was found,
+.I *valuep
+is set to NULL.
+.P
+When
+.BR getsubopt ()
+returns,
+.I optionp
+points to the next suboption,
+or to the null byte (\[aq]\e0\[aq]) at the end of the
+string if the last suboption was just processed.
+.SH RETURN VALUE
+If the first suboption in
+.I optionp
+is recognized,
+.BR getsubopt ()
+returns the index of the matching suboption element in
+.IR tokens .
+Otherwise, \-1 is returned and
+.I *valuep
+is the entire
+.IB name [= value ]
+string.
+.P
+Since
+.I *optionp
+is changed, the first suboption before the call to
+.BR getsubopt ()
+is not (necessarily) the same as the first suboption after
+.BR getsubopt ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getsubopt ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+Since
+.BR getsubopt ()
+overwrites any commas it finds in the string
+.IR *optionp ,
+that string must be writable; it cannot be a string constant.
+.SH EXAMPLES
+The following program expects suboptions following a "\-o" option.
+.P
+.\" SRC BEGIN (getsubopt.c)
+.EX
+#define _XOPEN_SOURCE 500
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#include <assert.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    enum {
+        RO_OPT = 0,
+        RW_OPT,
+        NAME_OPT
+    };
+    char *const token[] = {
+        [RO_OPT]   = "ro",
+        [RW_OPT]   = "rw",
+        [NAME_OPT] = "name",
+        NULL
+    };
+    char *subopts;
+    char *value;
+    int opt;
+\&
+    int readonly = 0;
+    int readwrite = 0;
+    char *name = NULL;
+    int errfnd = 0;
+\&
+    while ((opt = getopt(argc, argv, "o:")) != \-1) {
+        switch (opt) {
+        case \[aq]o\[aq]:
+            subopts = optarg;
+            while (*subopts != \[aq]\e0\[aq] && !errfnd) {
+\&
+                switch (getsubopt(&subopts, token, &value)) {
+                case RO_OPT:
+                    readonly = 1;
+                    break;
+\&
+                case RW_OPT:
+                    readwrite = 1;
+                    break;
+\&
+                case NAME_OPT:
+                    if (value == NULL) {
+                        fprintf(stderr,
+                                "Missing value for suboption \[aq]%s\[aq]\en",
+                                token[NAME_OPT]);
+                        errfnd = 1;
+                        continue;
+                    }
+\&
+                    name = value;
+                    break;
+\&
+                default:
+                    fprintf(stderr,
+                            "No match found for token: /%s/\en", value);
+                    errfnd = 1;
+                    break;
+                }
+            }
+            if (readwrite && readonly) {
+                fprintf(stderr,
+                        "Only one of \[aq]%s\[aq] and \[aq]%s\[aq] can be specified\en",
+                        token[RO_OPT], token[RW_OPT]);
+                errfnd = 1;
+            }
+            break;
+\&
+        default:
+            errfnd = 1;
+        }
+    }
+\&
+    if (errfnd || argc == 1) {
+        fprintf(stderr, "\enUsage: %s \-o <suboptstring>\en", argv[0]);
+        fprintf(stderr,
+                "suboptions are \[aq]ro\[aq], \[aq]rw\[aq], and \[aq]name=<value>\[aq]\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Remainder of program... */
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getopt (3)
diff --git a/man/man3/getttyent.3 b/man/man3/getttyent.3
new file mode 100644
index 000000000..7c694e5fe
--- /dev/null
+++ b/man/man3/getttyent.3
@@ -0,0 +1,100 @@
+'\" t
+.\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH getttyent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getttyent, getttynam, setttyent, endttyent \- get ttys file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <ttyent.h>"
+.P
+.B "struct ttyent *getttyent(void);"
+.BI "struct ttyent *getttynam(const char *" name );
+.P
+.B "int setttyent(void);"
+.B "int endttyent(void);"
+.fi
+.SH DESCRIPTION
+These functions provide an interface to the file
+.B _PATH_TTYS
+(e.g.,
+.IR /etc/ttys ).
+.P
+The function
+.BR setttyent ()
+opens the file or rewinds it if already open.
+.P
+The function
+.BR endttyent ()
+closes the file.
+.P
+The function
+.BR getttynam ()
+searches for a given terminal name in the file.
+It returns a pointer to a
+.I ttyent
+structure (description below).
+.P
+The function
+.BR getttyent ()
+opens the file
+.B _PATH_TTYS
+(if necessary) and returns the first entry.
+If the file is already open, the next entry.
+The
+.I ttyent
+structure has the form:
+.P
+.in +4n
+.EX
+struct ttyent {
+    char *ty_name;     /* terminal device name */
+    char *ty_getty;    /* command to execute, usually getty */
+    char *ty_type;     /* terminal type for termcap */
+    int   ty_status;   /* status flags */
+    char *ty_window;   /* command to start up window manager */
+    char *ty_comment;  /* comment field */
+};
+.EE
+.in
+.P
+.I ty_status
+can be:
+.P
+.in +4n
+.EX
+#define TTY_ON     0x01  /* enable logins (start ty_getty program) */
+#define TTY_SECURE 0x02  /* allow UID 0 to login */
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getttyent (),
+.BR setttyent (),
+.BR endttyent (),
+.BR getttynam ()
+T}	Thread safety	MT-Unsafe race:ttyent
+.TE
+.SH STANDARDS
+BSD.
+.SH NOTES
+Under Linux, the file
+.IR /etc/ttys ,
+and the functions described above, are not used.
+.SH SEE ALSO
+.BR ttyname (3),
+.BR ttyslot (3)
diff --git a/man/man3/getttynam.3 b/man/man3/getttynam.3
new file mode 100644
index 000000000..1cd11e3d8
--- /dev/null
+++ b/man/man3/getttynam.3
@@ -0,0 +1 @@
+.so man3/getttyent.3
diff --git a/man/man3/getusershell.3 b/man/man3/getusershell.3
new file mode 100644
index 000000000..77c7c0409
--- /dev/null
+++ b/man/man3/getusershell.3
@@ -0,0 +1,98 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:17:53 1993 by Rik Faith (faith@cs.unc.edu)
+.TH getusershell 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getusershell, setusershell, endusershell \- get permitted user shells
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.B char *getusershell(void);
+.B void setusershell(void);
+.B void endusershell(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getusershell (),
+.BR setusershell (),
+.BR endusershell ():
+.nf
+    Since glibc 2.21:
+.\"             commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+The
+.BR getusershell ()
+function returns the next line from the file
+.IR /etc/shells ,
+opening the file if necessary.
+The line should contain
+the pathname of a valid user shell.
+If
+.I /etc/shells
+does not exist or
+is unreadable,
+.BR getusershell ()
+behaves as if
+.I /bin/sh
+and
+.I /bin/csh
+were listed in the file.
+.P
+The
+.BR setusershell ()
+function rewinds
+.IR /etc/shells .
+.P
+The
+.BR endusershell ()
+function closes
+.IR /etc/shells .
+.SH RETURN VALUE
+The
+.BR getusershell ()
+function returns NULL on end-of-file.
+.SH FILES
+.I /etc/shells
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getusershell (),
+.BR setusershell (),
+.BR endusershell ()
+T}	Thread safety	MT-Unsafe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD.
+.SH SEE ALSO
+.BR shells (5)
diff --git a/man/man3/getutent.3 b/man/man3/getutent.3
new file mode 100644
index 000000000..656a52cd2
--- /dev/null
+++ b/man/man3/getutent.3
@@ -0,0 +1,355 @@
+'\" t
+.\" Copyright 1995 Mark D. Roth (roth@uiuc.edu)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Solaris manpages
+.\"
+.\" Modified Thu Jul 25 14:43:46 MET DST 1996 by Michael Haardt
+.\"     <michael@cantor.informatik.rwth-aachen.de>
+.\"
+.TH getutent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getutent, getutid, getutline, pututline, setutent, endutent,
+utmpname \- access utmp file entries
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <utmp.h>
+.P
+.B struct utmp *getutent(void);
+.BI "struct utmp *getutid(const struct utmp *" ut );
+.BI "struct utmp *getutline(const struct utmp *" ut );
+.P
+.BI "struct utmp *pututline(const struct utmp *" ut );
+.P
+.B void setutent(void);
+.B void endutent(void);
+.P
+.BI "int utmpname(const char *" file );
+.fi
+.SH DESCRIPTION
+New applications should use the POSIX.1-specified "utmpx" versions of
+these functions; see STANDARDS.
+.P
+.BR utmpname ()
+sets the name of the utmp-format file for the other utmp
+functions to access.
+If
+.BR utmpname ()
+is not used to set the filename
+before the other functions are used, they assume \fB_PATH_UTMP\fP, as
+defined in \fI<paths.h>\fP.
+.P
+.BR setutent ()
+rewinds the file pointer to the beginning of the utmp file.
+It is generally a good idea to call it before any of the other
+functions.
+.P
+.BR endutent ()
+closes the utmp file.
+It should be called when the user
+code is done accessing the file with the other functions.
+.P
+.BR getutent ()
+reads a line from the current file position in the utmp file.
+It returns a pointer to a structure containing the fields of
+the line.
+The definition of this structure is shown in
+.BR utmp (5).
+.P
+.BR getutid ()
+searches forward from the current file position in the utmp
+file based upon \fIut\fP.
+If \fIut\->ut_type\fP is one of \fBRUN_LVL\fP,
+\fBBOOT_TIME\fP, \fBNEW_TIME\fP, or \fBOLD_TIME\fP,
+.BR getutid ()
+will
+find the first entry whose \fIut_type\fP field matches \fIut\->ut_type\fP.
+If \fIut\->ut_type\fP is one of \fBINIT_PROCESS\fP, \fBLOGIN_PROCESS\fP,
+\fBUSER_PROCESS\fP, or \fBDEAD_PROCESS\fP,
+.BR getutid ()
+will find the
+first entry whose
+.I ut_id
+field matches \fIut\->ut_id\fP.
+.P
+.BR getutline ()
+searches forward from the current file position in the utmp file.
+It scans entries whose
+.I ut_type
+is \fBUSER_PROCESS\fP
+or \fBLOGIN_PROCESS\fP and returns the first one whose
+.I ut_line
+field
+matches \fIut\->ut_line\fP.
+.P
+.BR pututline ()
+writes the
+.I utmp
+structure \fIut\fP into the utmp file.
+It uses
+.BR getutid ()
+to search for the proper place in the file to insert
+the new entry.
+If it cannot find an appropriate slot for \fIut\fP,
+.BR pututline ()
+will append the new entry to the end of the file.
+.SH RETURN VALUE
+.BR getutent (),
+.BR getutid (),
+and
+.BR getutline ()
+return a pointer to a \fIstruct utmp\fP on success,
+and NULL on failure (which includes the "record not found" case).
+This \fIstruct utmp\fP is allocated in static storage, and may be
+overwritten by subsequent calls.
+.P
+On success
+.BR pututline ()
+returns
+.IR ut ;
+on failure, it returns NULL.
+.P
+.BR utmpname ()
+returns 0 if the new name was successfully stored, or \-1 on failure.
+.P
+On failure, these functions
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ESRCH
+Record not found.
+.P
+.BR setutent (),
+.BR pututline (),
+and the
+.BR getut* ()
+functions can also fail for the reasons described in
+.BR open (2).
+.SH FILES
+.TP
+.I /var/run/utmp
+database of currently logged-in users
+.TP
+.I /var/log/wtmp
+database of past user logins
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getutent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe init race:utent
+race:utentbuf sig:ALRM timer
+T}
+T{
+.na
+.nh
+.BR getutid (),
+.BR getutline ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe init race:utent
+sig:ALRM timer
+T}
+T{
+.na
+.nh
+.BR pututline ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:utent
+sig:ALRM timer
+T}
+T{
+.na
+.nh
+.BR setutent (),
+.BR endutent (),
+.BR utmpname ()
+T}	Thread safety	MT-Unsafe race:utent
+.TE
+.P
+In the above table,
+.I utent
+in
+.I race:utent
+signifies that if any of the functions
+.BR setutent (),
+.BR getutent (),
+.BR getutid (),
+.BR getutline (),
+.BR pututline (),
+.BR utmpname (),
+or
+.BR endutent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH STANDARDS
+None.
+.SH HISTORY
+XPG2, SVr4.
+.P
+In XPG2 and SVID 2 the function
+.BR pututline ()
+is documented to return void, and that is what it does on many systems
+(AIX, HP-UX).
+HP-UX introduces a new function
+.BR _pututline ()
+with the prototype given above for
+.BR pututline ().
+.P
+All these functions are obsolete now on non-Linux systems.
+POSIX.1-2001 and POSIX.1-2008, following SUSv1,
+does not have any of these functions, but instead uses
+.P
+.RS 4
+.EX
+.B #include <utmpx.h>
+.P
+.B struct utmpx *getutxent(void);
+.B struct utmpx *getutxid(const struct utmpx *);
+.B struct utmpx *getutxline(const struct utmpx *);
+.B struct utmpx *pututxline(const struct utmpx *);
+.B void setutxent(void);
+.B void endutxent(void);
+.EE
+.RE
+.P
+These functions are provided by glibc,
+and perform the same task as their equivalents without the "x", but use
+.IR "struct utmpx" ,
+defined on Linux to be the same as
+.IR "struct utmp" .
+For completeness, glibc also provides
+.BR utmpxname (),
+although this function is not specified by POSIX.1.
+.P
+On some other systems,
+the \fIutmpx\fP structure is a superset of the \fIutmp\fP structure,
+with additional fields, and larger versions of the existing fields,
+and parallel files are maintained, often
+.I /var/*/utmpx
+and
+.IR /var/*/wtmpx .
+.P
+Linux glibc on the other hand does not use a parallel \fIutmpx\fP file
+since its \fIutmp\fP structure is already large enough.
+The "x" functions listed above are just aliases for
+their counterparts without the "x" (e.g.,
+.BR getutxent ()
+is an alias for
+.BR getutent ()).
+.SH NOTES
+.SS glibc notes
+The above functions are not thread-safe.
+glibc adds reentrant versions
+.P
+.nf
+.B #include <utmp.h>
+.P
+.BI "int getutent_r(struct utmp *" ubuf ", struct utmp **" ubufp );
+.BI "int getutid_r(struct utmp *" ut ,
+.BI "              struct utmp *" ubuf ", struct utmp **" ubufp );
+.BI "int getutline_r(struct utmp *" ut ,
+.BI "                struct utmp *" ubuf ", struct utmp **" ubufp );
+.fi
+.P
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.P
+.BR getutent_r (),
+.BR getutid_r (),
+.BR getutline_r ():
+.nf
+    _GNU_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */    _SVID_SOURCE || _BSD_SOURCE
+.fi
+.P
+These functions are GNU extensions, analogs of the functions of the
+same name without the _r suffix.
+The
+.I ubuf
+argument gives these functions a place to store their result.
+On success, they return 0, and a pointer to the result is written in
+.IR *ubufp .
+On error, these functions return \-1.
+There are no utmpx equivalents of the above functions.
+(POSIX.1 does not specify such functions.)
+.SH EXAMPLES
+The following example adds and removes a utmp record, assuming it is run
+from within a pseudo terminal.
+For usage in a real application, you
+should check the return values of
+.BR getpwuid (3)
+and
+.BR ttyname (3).
+.P
+.\" SRC BEGIN (getutent.c)
+.EX
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <utmp.h>
+\&
+int
+main(void)
+{
+    struct utmp entry;
+\&
+    system("echo before adding entry:;who");
+\&
+    entry.ut_type = USER_PROCESS;
+    entry.ut_pid = getpid();
+    strcpy(entry.ut_line, ttyname(STDIN_FILENO) + strlen("/dev/"));
+    /* only correct for ptys named /dev/tty[pqr][0\-9a\-z] */
+    strcpy(entry.ut_id, ttyname(STDIN_FILENO) + strlen("/dev/tty"));
+    entry.ut_time = time(NULL);
+    strcpy(entry.ut_user, getpwuid(getuid())\->pw_name);
+    memset(entry.ut_host, 0, UT_HOSTSIZE);
+    entry.ut_addr = 0;
+    setutent();
+    pututline(&entry);
+\&
+    system("echo after adding entry:;who");
+\&
+    entry.ut_type = DEAD_PROCESS;
+    memset(entry.ut_line, 0, UT_LINESIZE);
+    entry.ut_time = 0;
+    memset(entry.ut_user, 0, UT_NAMESIZE);
+    setutent();
+    pututline(&entry);
+\&
+    system("echo after removing entry:;who");
+\&
+    endutent();
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getutmp (3),
+.BR utmp (5)
diff --git a/man/man3/getutent_r.3 b/man/man3/getutent_r.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutent_r.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getutid.3 b/man/man3/getutid.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutid.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getutid_r.3 b/man/man3/getutid_r.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutid_r.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getutline.3 b/man/man3/getutline.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutline.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getutline_r.3 b/man/man3/getutline_r.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutline_r.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getutmp.3 b/man/man3/getutmp.3
new file mode 100644
index 000000000..d3e774a81
--- /dev/null
+++ b/man/man3/getutmp.3
@@ -0,0 +1,71 @@
+'\" t
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getutmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getutmp, getutmpx \- copy utmp structure to utmpx, and vice versa
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <utmpx.h>
+.P
+.BI "void getutmp(const struct utmpx *" ux ", struct utmp *" u );
+.BI "void getutmpx(const struct utmp *" u ", struct utmpx *" ux );
+.fi
+.SH DESCRIPTION
+The
+.BR getutmp ()
+function copies the fields of the
+.I utmpx
+structure pointed to by
+.I ux
+to the corresponding fields of the
+.I utmp
+structure pointed to by
+.IR u .
+The
+.BR getutmpx ()
+function performs the converse operation.
+.SH RETURN VALUE
+These functions do not return a value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getutmp (),
+.BR getutmpx ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.1.1.
+Solaris, NetBSD.
+.SH NOTES
+These functions exist primarily for compatibility with other
+systems where the
+.I utmp
+and
+.I utmpx
+structures contain different fields,
+or the size of corresponding fields differs.
+.\" e.g., on Solaris, the utmpx structure is rather larger than utmp.
+On Linux, the two structures contain the same fields,
+and the fields have the same sizes.
+.SH SEE ALSO
+.BR utmpdump (1),
+.BR getutent (3),
+.BR utmp (5)
diff --git a/man/man3/getutmpx.3 b/man/man3/getutmpx.3
new file mode 100644
index 000000000..668ecb5d7
--- /dev/null
+++ b/man/man3/getutmpx.3
@@ -0,0 +1 @@
+.so man3/getutmp.3
diff --git a/man/man3/getutxent.3 b/man/man3/getutxent.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutxent.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getutxid.3 b/man/man3/getutxid.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutxid.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getutxline.3 b/man/man3/getutxline.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/getutxline.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/getw.3 b/man/man3/getw.3
new file mode 100644
index 000000000..e41b7d8a4
--- /dev/null
+++ b/man/man3/getw.3
@@ -0,0 +1,84 @@
+'\" t
+.\" Copyright (c) 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH getw 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getw, putw \- input and output of words (ints)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int getw(FILE *" stream );
+.BI "int putw(int " w ", FILE *" stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR getw (),
+.BR putw ():
+.nf
+    Since glibc 2.3.3:
+        _XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+    Before glibc 2.3.3:
+        _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+.BR getw ()
+reads a word (that is, an \fIint\fP) from \fIstream\fP.
+It's provided for compatibility with SVr4.
+We recommend you use
+.BR fread (3)
+instead.
+.P
+.BR putw ()
+writes the word \fIw\fP (that is,
+an \fIint\fP) to \fIstream\fP.
+It is provided for compatibility with SVr4, but we recommend you use
+.BR fwrite (3)
+instead.
+.SH RETURN VALUE
+Normally,
+.BR getw ()
+returns the word read, and
+.BR putw ()
+returns 0.
+On error, they return \fBEOF\fP.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getw (),
+.BR putw ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4, SUSv2.
+.SH BUGS
+The value returned on error is also a legitimate data value.
+.BR ferror (3)
+can be used to distinguish between the two cases.
+.SH SEE ALSO
+.BR ferror (3),
+.BR fread (3),
+.BR fwrite (3),
+.BR getc (3),
+.BR putc (3)
diff --git a/man/man3/getwc.3 b/man/man3/getwc.3
new file mode 100644
index 000000000..358c2d214
--- /dev/null
+++ b/man/man3/getwc.3
@@ -0,0 +1 @@
+.so man3/fgetwc.3
diff --git a/man/man3/getwc_unlocked.3 b/man/man3/getwc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/getwc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/getwchar.3 b/man/man3/getwchar.3
new file mode 100644
index 000000000..4dd9c16f7
--- /dev/null
+++ b/man/man3/getwchar.3
@@ -0,0 +1,87 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification
+.\"      http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH getwchar 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getwchar \- read a wide character from standard input
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.B "wint_t getwchar(void);"
+.fi
+.SH DESCRIPTION
+The
+.BR getwchar ()
+function is the wide-character equivalent of the
+.BR getchar (3)
+function.
+It reads a wide character from
+.I stdin
+and returns
+it.
+If the end of stream is reached, or if
+.I ferror(stdin)
+becomes true, it returns
+.BR WEOF .
+If a wide-character conversion error occurs, it sets
+.I errno
+to
+.B EILSEQ
+and returns
+.BR WEOF .
+.P
+For a nonlocking counterpart, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+The
+.BR getwchar ()
+function returns the next wide-character from
+standard input, or
+.BR WEOF .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getwchar ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH NOTES
+The behavior of
+.BR getwchar ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+It is reasonable to expect that
+.BR getwchar ()
+will actually
+read a multibyte sequence from standard input and then
+convert it to a wide character.
+.SH SEE ALSO
+.BR fgetwc (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/getwchar_unlocked.3 b/man/man3/getwchar_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/getwchar_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/getwd.3 b/man/man3/getwd.3
new file mode 100644
index 000000000..f73c1579c
--- /dev/null
+++ b/man/man3/getwd.3
@@ -0,0 +1 @@
+.so man3/getcwd.3
diff --git a/man/man3/glob.3 b/man/man3/glob.3
new file mode 100644
index 000000000..130a6ce60
--- /dev/null
+++ b/man/man3/glob.3
@@ -0,0 +1,353 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Wed Jul 28 11:12:17 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon May 13 23:08:50 1996 by Martin Schulze (joey@linux.de)
+.\" Modified 11 May 1998 by Joseph S. Myers (jsm28@cam.ac.uk)
+.\" Modified 990912 by aeb
+.\" 2007-10-10 mtk
+.\"     Added description of GLOB_TILDE_NOMATCH
+.\"     Expanded the description of various flags
+.\"     Various wording fixes.
+.\"
+.TH glob 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+glob, globfree \- find pathnames matching a pattern, free memory from glob()
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <glob.h>
+.P
+.BI "int glob(const char *restrict " pattern ", int " flags ,
+.BI "         int (*" errfunc ")(const char *" epath ", int " eerrno ),
+.BI "         glob_t *restrict " pglob );
+.BI "void globfree(glob_t *" pglob );
+.fi
+.SH DESCRIPTION
+The
+.BR glob ()
+function searches for all the pathnames matching
+.I pattern
+according to the rules used by the shell (see
+.BR glob (7)).
+No tilde expansion or parameter substitution is done; if you want
+these, use
+.BR wordexp (3).
+.P
+The
+.BR globfree ()
+function frees the dynamically allocated storage from an earlier call
+to
+.BR glob ().
+.P
+The results of a
+.BR glob ()
+call are stored in the structure pointed to by
+.IR pglob .
+This structure is of type
+.I glob_t
+(declared in
+.IR <glob.h> )
+and includes the following elements defined by POSIX.2 (more may be
+present as an extension):
+.P
+.in +4n
+.EX
+typedef struct {
+    size_t   gl_pathc;    /* Count of paths matched so far  */
+    char   **gl_pathv;    /* List of matched pathnames.  */
+    size_t   gl_offs;     /* Slots to reserve in \fIgl_pathv\fP.  */
+} glob_t;
+.EE
+.in
+.P
+Results are stored in dynamically allocated storage.
+.P
+The argument
+.I flags
+is made up of the bitwise OR of zero or more the following symbolic
+constants, which modify the behavior of
+.BR glob ():
+.TP
+.B GLOB_ERR
+Return upon a read error (because a directory does not
+have read permission, for example).
+By default,
+.BR glob ()
+attempts carry on despite errors,
+reading all of the directories that it can.
+.TP
+.B GLOB_MARK
+Append a slash to each path which corresponds to a directory.
+.TP
+.B GLOB_NOSORT
+Don't sort the returned pathnames.
+The only reason to do this is to save processing time.
+By default, the returned pathnames are sorted.
+.TP
+.B GLOB_DOOFFS
+Reserve
+.I pglob\->gl_offs
+slots at the beginning of the list of strings in
+.IR pglob\->pathv .
+The reserved slots contain null pointers.
+.TP
+.B GLOB_NOCHECK
+If no pattern matches, return the original pattern.
+By default,
+.BR glob ()
+returns
+.B GLOB_NOMATCH
+if there are no matches.
+.TP
+.B GLOB_APPEND
+Append the results of this call to the vector of results
+returned by a previous call to
+.BR glob ().
+Do not set this flag on the first invocation of
+.BR glob ().
+.TP
+.B GLOB_NOESCAPE
+Don't allow backslash (\[aq]\e\[aq]) to be used as an escape
+character.
+Normally, a backslash can be used to quote the following character,
+providing a mechanism to turn off the special meaning
+metacharacters.
+.P
+.I flags
+may also include any of the following, which are GNU
+extensions and not defined by POSIX.2:
+.TP
+.B GLOB_PERIOD
+Allow a leading period to be matched by metacharacters.
+By default, metacharacters can't match a leading period.
+.TP
+.B GLOB_ALTDIRFUNC
+Use alternative functions
+.IR pglob\->gl_closedir ,
+.IR pglob\->gl_readdir ,
+.IR pglob\->gl_opendir ,
+.IR pglob\->gl_lstat ,
+and
+.I pglob\->gl_stat
+for filesystem access instead of the normal library
+functions.
+.TP
+.B GLOB_BRACE
+Expand
+.BR csh (1)
+style brace expressions of the form
+.BR {a,b} .
+Brace expressions can be nested.
+Thus, for example, specifying the pattern
+"{foo/{,cat,dog},bar}" would return the same results as four separate
+.BR glob ()
+calls using the strings:
+"foo/",
+"foo/cat",
+"foo/dog",
+and
+"bar".
+.TP
+.B GLOB_NOMAGIC
+If the pattern contains no metacharacters,
+then it should be returned as the sole matching word,
+even if there is no file with that name.
+.TP
+.B GLOB_TILDE
+Carry out tilde expansion.
+If a tilde (\[aq]\[ti]\[aq]) is the only character in the pattern,
+or an initial tilde is followed immediately by a slash (\[aq]/\[aq]),
+then the home directory of the caller is substituted for
+the tilde.
+If an initial tilde is followed by a username (e.g., "\[ti]andrea/bin"),
+then the tilde and username are substituted by the home directory
+of that user.
+If the username is invalid, or the home directory cannot be
+determined, then no substitution is performed.
+.TP
+.B GLOB_TILDE_CHECK
+This provides behavior similar to that of
+.BR GLOB_TILDE .
+The difference is that if the username is invalid, or the
+home directory cannot be determined, then
+instead of using the pattern itself as the name,
+.BR glob ()
+returns
+.B GLOB_NOMATCH
+to indicate an error.
+.TP
+.B GLOB_ONLYDIR
+This is a
+.I hint
+to
+.BR glob ()
+that the caller is interested only in directories that match the pattern.
+If the implementation can easily determine file-type information,
+then nondirectory files are not returned to the caller.
+However, the caller must still check that returned files
+are directories.
+(The purpose of this flag is merely to optimize performance when
+the caller is interested only in directories.)
+.P
+If
+.I errfunc
+is not NULL,
+it will be called in case of an error with the arguments
+.IR epath ,
+a pointer to the path which failed, and
+.IR eerrno ,
+the value of
+.I errno
+as returned from one of the calls to
+.BR opendir (3),
+.BR readdir (3),
+or
+.BR stat (2).
+If
+.I errfunc
+returns nonzero, or if
+.B GLOB_ERR
+is set,
+.BR glob ()
+will terminate after the call to
+.IR errfunc .
+.P
+Upon successful return,
+.I pglob\->gl_pathc
+contains the number of matched pathnames and
+.I pglob\->gl_pathv
+contains a pointer to the list of pointers to matched pathnames.
+The list of pointers is terminated by a null pointer.
+.P
+It is possible to call
+.BR glob ()
+several times.
+In that case, the
+.B GLOB_APPEND
+flag has to be set in
+.I flags
+on the second and later invocations.
+.P
+As a GNU extension,
+.I pglob\->gl_flags
+is set to the flags specified,
+.BR or ed
+with
+.B GLOB_MAGCHAR
+if any metacharacters were found.
+.SH RETURN VALUE
+On successful completion,
+.BR glob ()
+returns zero.
+Other possible returns are:
+.TP
+.B GLOB_NOSPACE
+for running out of memory,
+.TP
+.B GLOB_ABORTED
+for a read error, and
+.TP
+.B GLOB_NOMATCH
+for no found matches.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR glob ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:utent env
+sig:ALRM timer locale
+T}
+T{
+.na
+.nh
+.BR globfree ()
+T}	Thread safety	MT-Safe
+.TE
+.P
+In the above table,
+.I utent
+in
+.I race:utent
+signifies that if any of the functions
+.BR setutent (3),
+.BR getutent (3),
+or
+.BR endutent (3)
+are used in parallel in different threads of a program,
+then data races could occur.
+.BR glob ()
+calls those functions,
+so we use race:utent to remind users.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, POSIX.2.
+.SH NOTES
+The structure elements
+.I gl_pathc
+and
+.I gl_offs
+are declared as
+.I size_t
+in glibc 2.1, as they should be according to POSIX.2,
+but are declared as
+.I int
+in glibc 2.0.
+.SH BUGS
+The
+.BR glob ()
+function may fail due to failure of underlying function calls, such as
+.BR malloc (3)
+or
+.BR opendir (3).
+These will store their error code in
+.IR errno .
+.SH EXAMPLES
+One example of use is the following code, which simulates typing
+.P
+.in +4n
+.EX
+ls \-l *.c ../*.c
+.EE
+.in
+.P
+in the shell:
+.P
+.in +4n
+.EX
+glob_t globbuf;
+\&
+globbuf.gl_offs = 2;
+glob("*.c", GLOB_DOOFFS, NULL, &globbuf);
+glob("../*.c", GLOB_DOOFFS | GLOB_APPEND, NULL, &globbuf);
+globbuf.gl_pathv[0] = "ls";
+globbuf.gl_pathv[1] = "\-l";
+execvp("ls", &globbuf.gl_pathv[0]);
+.EE
+.in
+.SH SEE ALSO
+.BR ls (1),
+.BR sh (1),
+.BR stat (2),
+.BR exec (3),
+.BR fnmatch (3),
+.BR malloc (3),
+.BR opendir (3),
+.BR readdir (3),
+.BR wordexp (3),
+.BR glob (7)
diff --git a/man/man3/globfree.3 b/man/man3/globfree.3
new file mode 100644
index 000000000..20056c69a
--- /dev/null
+++ b/man/man3/globfree.3
@@ -0,0 +1 @@
+.so man3/glob.3
diff --git a/man/man3/gmtime.3 b/man/man3/gmtime.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/gmtime.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/gmtime_r.3 b/man/man3/gmtime_r.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/gmtime_r.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/gnu_dev_major.3 b/man/man3/gnu_dev_major.3
new file mode 100644
index 000000000..eabbdd013
--- /dev/null
+++ b/man/man3/gnu_dev_major.3
@@ -0,0 +1 @@
+.so man3/makedev.3
diff --git a/man/man3/gnu_dev_makedev.3 b/man/man3/gnu_dev_makedev.3
new file mode 100644
index 000000000..eabbdd013
--- /dev/null
+++ b/man/man3/gnu_dev_makedev.3
@@ -0,0 +1 @@
+.so man3/makedev.3
diff --git a/man/man3/gnu_dev_minor.3 b/man/man3/gnu_dev_minor.3
new file mode 100644
index 000000000..eabbdd013
--- /dev/null
+++ b/man/man3/gnu_dev_minor.3
@@ -0,0 +1 @@
+.so man3/makedev.3
diff --git a/man/man3/gnu_get_libc_release.3 b/man/man3/gnu_get_libc_release.3
new file mode 100644
index 000000000..7f84005f3
--- /dev/null
+++ b/man/man3/gnu_get_libc_release.3
@@ -0,0 +1 @@
+.so man3/gnu_get_libc_version.3
diff --git a/man/man3/gnu_get_libc_version.3 b/man/man3/gnu_get_libc_version.3
new file mode 100644
index 000000000..d08ecc4b9
--- /dev/null
+++ b/man/man3/gnu_get_libc_version.3
@@ -0,0 +1,79 @@
+'\" t
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH gnu_get_libc_version 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gnu_get_libc_version, gnu_get_libc_release \- get glibc version and release
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <gnu/libc\-version.h>
+.P
+.B const char *gnu_get_libc_version(void);
+.B const char *gnu_get_libc_release(void);
+.fi
+.SH DESCRIPTION
+The function
+.BR gnu_get_libc_version ()
+returns a string that identifies the glibc version available on the system.
+.P
+The function
+.BR gnu_get_libc_release ()
+returns a string indicates the release status of the glibc version
+available on the system.
+This will be a string such as
+.IR "stable" .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR gnu_get_libc_version (),
+.BR gnu_get_libc_release ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.SH EXAMPLES
+When run, the program below will produce output such as the following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+GNU libc version: 2.8
+GNU libc release: stable
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (gnu_get_libc_version.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#include <gnu/libc\-version.h>
+\&
+int
+main(void)
+{
+    printf("GNU libc version: %s\en", gnu_get_libc_version());
+    printf("GNU libc release: %s\en", gnu_get_libc_release());
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR confstr (3)
diff --git a/man/man3/grantpt.3 b/man/man3/grantpt.3
new file mode 100644
index 000000000..94526691b
--- /dev/null
+++ b/man/man3/grantpt.3
@@ -0,0 +1,107 @@
+'\" t
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This page is in the public domain. - aeb
+.\" %%%LICENSE_END
+.\"
+.TH grantpt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+grantpt \- grant access to the slave pseudoterminal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int grantpt(int " fd ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR grantpt ():
+.nf
+    Since glibc 2.24:
+        _XOPEN_SOURCE >= 500
+.\"        || (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+    glibc 2.23 and earlier:
+        _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR grantpt ()
+function changes the mode and owner of the slave pseudoterminal device
+corresponding to the master pseudoterminal referred to by the file descriptor
+.IR fd .
+The user ID of the slave is set to the real UID of the calling process.
+The group ID is set to an unspecified value (e.g.,
+.IR tty ).
+The mode of the slave is set to 0620 (crw\-\-w\-\-\-\-).
+.P
+The behavior of
+.BR grantpt ()
+is unspecified if a signal handler is installed to catch
+.B SIGCHLD
+signals.
+.SH RETURN VALUE
+When successful,
+.BR grantpt ()
+returns 0.
+Otherwise, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The corresponding slave pseudoterminal could not be accessed.
+.TP
+.B EBADF
+The
+.I fd
+argument is not a valid open file descriptor.
+.TP
+.B EINVAL
+The
+.I fd
+argument is valid but not associated with a master pseudoterminal.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR grantpt ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.P
+This is part of the UNIX 98 pseudoterminal support, see
+.BR pts (4).
+.P
+Historical systems implemented this function via a set-user-ID helper binary
+called "pt_chown".
+glibc on Linux before glibc 2.33 could do so as well,
+in order to support configurations with only BSD pseudoterminals;
+this support has been removed.
+On modern systems this is either a no-op
+\[em]with permissions configured on pty allocation, as is the case on Linux\[em]
+or an
+.BR ioctl (2).
+.SH SEE ALSO
+.BR open (2),
+.BR posix_openpt (3),
+.BR ptsname (3),
+.BR unlockpt (3),
+.BR pts (4),
+.BR pty (7)
diff --git a/man/man3/group_member.3 b/man/man3/group_member.3
new file mode 100644
index 000000000..7985b89be
--- /dev/null
+++ b/man/man3/group_member.3
@@ -0,0 +1,48 @@
+.\" Copyright (C) 2014, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH group_member 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+group_member \- test whether a process is in a group
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int group_member(gid_t " gid );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR group_member ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR group_member ()
+function tests whether any of the caller's supplementary group IDs
+(as returned by
+.BR getgroups (2))
+matches
+.IR gid .
+.SH RETURN VALUE
+The
+.BR group_member ()
+function returns nonzero if any of the caller's
+supplementary group IDs matches
+.IR gid ,
+and zero otherwise.
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR getgid (2),
+.BR getgroups (2),
+.BR getgrouplist (3),
+.BR group (5)
diff --git a/man/man3/gsignal.3 b/man/man3/gsignal.3
new file mode 100644
index 000000000..538837a63
--- /dev/null
+++ b/man/man3/gsignal.3
@@ -0,0 +1,118 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" This replaces an earlier man page written by Walter Harms
+.\" <walter.harms@informatik.uni-oldenburg.de>.
+.TH gsignal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gsignal, ssignal \- software signal facility
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.B typedef void (*sighandler_t)(int);
+.P
+.BI "[[deprecated]] int gsignal(int " signum );
+.P
+.BI "[[deprecated]] sighandler_t ssignal(int " signum ", sighandler_t " action );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR gsignal (),
+.BR ssignal ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+Don't use these functions under Linux.
+Due to a historical mistake, under Linux these functions are
+aliases for
+.BR raise (3)
+and
+.BR signal (2),
+respectively.
+.P
+Elsewhere, on System V-like systems, these functions implement
+software signaling, entirely independent of the classical
+.BR signal (2)
+and
+.BR kill (2)
+functions.
+The function
+.BR ssignal ()
+defines the action to take when the software signal with
+number
+.I signum
+is raised using the function
+.BR gsignal (),
+and returns the previous such action or
+.BR SIG_DFL .
+The function
+.BR gsignal ()
+does the following: if no action (or the action
+.BR SIG_DFL )
+was
+specified for
+.IR signum ,
+then it does nothing and returns 0.
+If the action
+.B SIG_IGN
+was specified for
+.IR signum ,
+then it does nothing and returns 1.
+Otherwise, it resets the action to
+.B SIG_DFL
+and calls
+the action function with argument
+.IR signum ,
+and returns the value returned by that function.
+The range of possible values
+.I signum
+varies (often 1\[en]15 or 1\[en]17).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR gsignal ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR ssignal ()
+T}	Thread safety	MT-Safe sigintr
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+AIX, DG/UX, HP-UX, SCO, Solaris, Tru64.
+They are called obsolete under most of these systems, and are
+broken under
+.\" Linux libc and
+glibc.
+Some systems also have
+.BR gsignal_r ()
+and
+.BR ssignal_r ().
+.SH SEE ALSO
+.BR kill (2),
+.BR signal (2),
+.BR raise (3)
diff --git a/man/man3/h_errno.3 b/man/man3/h_errno.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/h_errno.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/hash.3 b/man/man3/hash.3
new file mode 100644
index 000000000..b40623a47
--- /dev/null
+++ b/man/man3/hash.3
@@ -0,0 +1,145 @@
+.\" Copyright (c) 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	@(#)hash.3	8.6 (Berkeley) 8/18/94
+.\"
+.TH hash 3 (date) "Linux man-pages (unreleased)"
+.UC 7
+.SH NAME
+hash \- hash database access method
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.ft B
+#include <sys/types.h>
+#include <db.h>
+.ft R
+.fi
+.SH DESCRIPTION
+.IR "Note well" :
+This page documents interfaces provided up until glibc 2.1.
+Since glibc 2.2, glibc no longer provides these interfaces.
+Probably, you are looking for the APIs provided by the
+.I libdb
+library instead.
+.P
+The routine
+.BR dbopen (3)
+is the library interface to database files.
+One of the supported file formats is hash files.
+The general description of the database access methods is in
+.BR dbopen (3),
+this manual page describes only the hash-specific information.
+.P
+The hash data structure is an extensible, dynamic hashing scheme.
+.P
+The access-method-specific data structure provided to
+.BR dbopen (3)
+is defined in the
+.I <db.h>
+include file as follows:
+.P
+.in +4n
+.EX
+typedef struct {
+    unsigned int       bsize;
+    unsigned int       ffactor;
+    unsigned int       nelem;
+    unsigned int       cachesize;
+    uint32_t         (*hash)(const void *, size_t);
+    int         lorder;
+} HASHINFO;
+.EE
+.in
+.P
+The elements of this structure are as follows:
+.TP 10
+.I bsize
+defines the hash table bucket size, and is, by default, 256 bytes.
+It may be preferable to increase the page size for disk-resident tables
+and tables with large data items.
+.TP
+.I ffactor
+indicates a desired density within the hash table.
+It is an approximation of the number of keys allowed to accumulate in any
+one bucket, determining when the hash table grows or shrinks.
+The default value is 8.
+.TP
+.I nelem
+is an estimate of the final size of the hash table.
+If not set or set too low, hash tables will expand gracefully as keys
+are entered, although a slight performance degradation may be noticed.
+The default value is 1.
+.TP
+.I cachesize
+is the suggested maximum size, in bytes, of the memory cache.
+This value is
+.IR "only advisory" ,
+and the access method will allocate more memory rather than fail.
+.TP
+.I hash
+is a user-defined hash function.
+Since no hash function performs equally well on all possible data, the
+user may find that the built-in hash function does poorly on a particular
+data set.
+A user-specified hash functions must take two arguments (a pointer to a byte
+string and a length) and return a 32-bit quantity to be used as the hash
+value.
+.TP
+.I lorder
+is the byte order for integers in the stored database metadata.
+The number should represent the order as an integer; for example,
+big endian order would be the number 4,321.
+If
+.I lorder
+is 0 (no order is specified), the current host order is used.
+If the file already exists, the specified value is ignored and the
+value specified when the tree was created is used.
+.P
+If the file already exists (and the
+.B O_TRUNC
+flag is not specified), the
+values specified for
+.IR bsize ,
+.IR ffactor ,
+.IR lorder ,
+and
+.I nelem
+are
+ignored and the values specified when the tree was created are used.
+.P
+If a hash function is specified,
+.I hash_open
+attempts to determine if the hash function specified is the same as
+the one with which the database was created, and fails if it is not.
+.P
+Backward-compatible interfaces to the routines described in
+.BR dbm (3),
+and
+.BR ndbm (3)
+are provided, however these interfaces are not compatible with
+previous file formats.
+.SH ERRORS
+The
+.I hash
+access method routines may fail and set
+.I errno
+for any of the errors specified for the library routine
+.BR dbopen (3).
+.SH BUGS
+Only big and little endian byte order are supported.
+.SH SEE ALSO
+.BR btree (3),
+.BR dbopen (3),
+.BR mpool (3),
+.BR recno (3)
+.P
+.IR "Dynamic Hash Tables" ,
+Per-Ake Larson, Communications of the ACM, April 1988.
+.P
+.IR "A New Hash Package for UNIX" ,
+Margo Seltzer, USENIX Proceedings, Winter 1991.
diff --git a/man/man3/hasmntopt.3 b/man/man3/hasmntopt.3
new file mode 100644
index 000000000..3c2bb35c9
--- /dev/null
+++ b/man/man3/hasmntopt.3
@@ -0,0 +1 @@
+.so man3/getmntent.3
diff --git a/man/man3/hcreate.3 b/man/man3/hcreate.3
new file mode 100644
index 000000000..f4a0405da
--- /dev/null
+++ b/man/man3/hcreate.3
@@ -0,0 +1 @@
+.so man3/hsearch.3
diff --git a/man/man3/hcreate_r.3 b/man/man3/hcreate_r.3
new file mode 100644
index 000000000..f4a0405da
--- /dev/null
+++ b/man/man3/hcreate_r.3
@@ -0,0 +1 @@
+.so man3/hsearch.3
diff --git a/man/man3/hdestroy.3 b/man/man3/hdestroy.3
new file mode 100644
index 000000000..f4a0405da
--- /dev/null
+++ b/man/man3/hdestroy.3
@@ -0,0 +1 @@
+.so man3/hsearch.3
diff --git a/man/man3/hdestroy_r.3 b/man/man3/hdestroy_r.3
new file mode 100644
index 000000000..f4a0405da
--- /dev/null
+++ b/man/man3/hdestroy_r.3
@@ -0,0 +1 @@
+.so man3/hsearch.3
diff --git a/man/man3/herror.3 b/man/man3/herror.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/herror.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/hsearch.3 b/man/man3/hsearch.3
new file mode 100644
index 000000000..1234228c0
--- /dev/null
+++ b/man/man3/hsearch.3
@@ -0,0 +1,355 @@
+'\" t
+.\" Copyright 1993 Ulrich Drepper (drepper@karlsruhe.gmd.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"     SunOS 4.1.1 man pages
+.\" Modified Sat Sep 30 21:52:01 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" Remarks from dhw@gamgee.acad.emich.edu Fri Jun 19 06:46:31 1998
+.\" Modified 2001-12-26, 2003-11-28, 2004-05-20, aeb
+.\" 2008-09-02, mtk: various additions and rewrites
+.\" 2008-09-03, mtk, restructured somewhat, in part after suggestions from
+.\"     Timothy S. Nelson <wayland@wayland.id.au>
+.\"
+.TH hsearch 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hcreate, hdestroy, hsearch, hcreate_r, hdestroy_r,
+hsearch_r \- hash table management
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <search.h>
+.P
+.BI "int hcreate(size_t " nel );
+.B "void hdestroy(void);"
+.P
+.BI "ENTRY *hsearch(ENTRY " item ", ACTION " action );
+.P
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <search.h>
+.P
+.BI "int hcreate_r(size_t " nel ", struct hsearch_data *" htab );
+.BI "void hdestroy_r(struct hsearch_data *" htab );
+.P
+.BI "int hsearch_r(ENTRY " item ", ACTION " action ", ENTRY **" retval ,
+.BI "              struct hsearch_data *" htab );
+.fi
+.SH DESCRIPTION
+The three functions
+.BR hcreate (),
+.BR hsearch (),
+and
+.BR hdestroy ()
+allow the caller to create and manage a hash search table
+containing entries consisting of a key (a string) and associated data.
+Using these functions, only one hash table can be used at a time.
+.P
+The three functions
+.BR hcreate_r (),
+.BR hsearch_r (),
+.BR hdestroy_r ()
+are reentrant versions that allow a program to use
+more than one hash search table at the same time.
+The last argument,
+.IR htab ,
+points to a structure that describes the table
+on which the function is to operate.
+The programmer should treat this structure as opaque
+(i.e., do not attempt to directly access or modify
+the fields in this structure).
+.P
+First a hash table must be created using
+.BR hcreate ().
+The argument \fInel\fP specifies the maximum number of entries
+in the table.
+(This maximum cannot be changed later, so choose it wisely.)
+The implementation may adjust this value upward to improve the
+performance of the resulting hash table.
+.\" e.g., in glibc it is raised to the next higher prime number
+.P
+The
+.BR hcreate_r ()
+function performs the same task as
+.BR hcreate (),
+but for the table described by the structure
+.IR *htab .
+The structure pointed to by
+.I htab
+must be zeroed before the first call to
+.BR hcreate_r ().
+.P
+The function
+.BR hdestroy ()
+frees the memory occupied by the hash table that was created by
+.BR hcreate ().
+After calling
+.BR hdestroy (),
+a new hash table can be created using
+.BR hcreate ().
+The
+.BR hdestroy_r ()
+function performs the analogous task for a hash table described by
+.IR *htab ,
+which was previously created using
+.BR hcreate_r ().
+.P
+The
+.BR hsearch ()
+function searches the hash table for an
+item with the same key as \fIitem\fP (where "the same" is determined using
+.BR strcmp (3)),
+and if successful returns a pointer to it.
+.P
+The argument \fIitem\fP is of type \fIENTRY\fP, which is defined in
+\fI<search.h>\fP as follows:
+.P
+.in +4n
+.EX
+typedef struct entry {
+    char *key;
+    void *data;
+} ENTRY;
+.EE
+.in
+.P
+The field \fIkey\fP points to a null-terminated string which is the
+search key.
+The field \fIdata\fP points to data that is associated with that key.
+.P
+The argument \fIaction\fP determines what
+.BR hsearch ()
+does after an unsuccessful search.
+This argument must either have the value
+.BR ENTER ,
+meaning insert a copy of
+.I item
+(and return a pointer to the new hash table entry as the function result),
+or the value
+.BR FIND ,
+meaning that NULL should be returned.
+(If
+.I action
+is
+.BR FIND ,
+then
+.I data
+is ignored.)
+.P
+The
+.BR hsearch_r ()
+function is like
+.BR hsearch ()
+but operates on the hash table described by
+.IR *htab .
+The
+.BR hsearch_r ()
+function differs from
+.BR hsearch ()
+in that a pointer to the found item is returned in
+.IR *retval ,
+rather than as the function result.
+.SH RETURN VALUE
+.BR hcreate ()
+and
+.BR hcreate_r ()
+return nonzero on success.
+They return 0 on error, with
+.I errno
+set to indicate the error.
+.P
+On success,
+.BR hsearch ()
+returns a pointer to an entry in the hash table.
+.BR hsearch ()
+returns NULL on error, that is,
+if \fIaction\fP is \fBENTER\fP and
+the hash table is full, or \fIaction\fP is \fBFIND\fP and \fIitem\fP
+cannot be found in the hash table.
+.BR hsearch_r ()
+returns nonzero on success, and 0 on error.
+In the event of an error, these two functions set
+.I errno
+to indicate the error.
+.SH ERRORS
+.BR hcreate_r ()
+and
+.BR hdestroy_r ()
+can fail for the following reasons:
+.TP
+.B EINVAL
+.I htab
+is NULL.
+.P
+.BR hsearch ()
+and
+.BR hsearch_r ()
+can fail for the following reasons:
+.TP
+.B ENOMEM
+.I action
+was
+.BR ENTER ,
+.I key
+was not found in the table,
+and there was no room in the table to add a new entry.
+.TP
+.B ESRCH
+.I action
+was
+.BR FIND ,
+and
+.I key
+was not found in the table.
+.P
+POSIX.1 specifies only the
+.\" PROX.1-2001, POSIX.1-2008
+.B ENOMEM
+error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR hcreate (),
+.BR hsearch (),
+.BR hdestroy ()
+T}	Thread safety	MT-Unsafe race:hsearch
+T{
+.na
+.nh
+.BR hcreate_r (),
+.BR hsearch_r (),
+.BR hdestroy_r ()
+T}	Thread safety	MT-Safe race:htab
+.TE
+.SH STANDARDS
+.TP
+.BR hcreate ()
+.TQ
+.BR hsearch ()
+.TQ
+.BR hdestroy ()
+POSIX.1-2008.
+.TP
+.BR hcreate_r ()
+.TQ
+.BR hsearch_r ()
+.TQ
+.BR hdestroy_r ()
+GNU.
+.SH HISTORY
+.TP
+.BR hcreate ()
+.TQ
+.BR hsearch ()
+.TQ
+.BR hdestroy ()
+SVr4, POSIX.1-2001.
+.TP
+.BR hcreate_r ()
+.TQ
+.BR hsearch_r ()
+.TQ
+.BR hdestroy_r ()
+GNU.
+.SH NOTES
+Hash table implementations are usually more efficient when the
+table contains enough free space to minimize collisions.
+Typically, this means that
+.I nel
+should be at least 25% larger than the maximum number of elements
+that the caller expects to store in the table.
+.P
+The
+.BR hdestroy ()
+and
+.BR hdestroy_r ()
+functions do not free the buffers pointed to by the
+.I key
+and
+.I data
+elements of the hash table entries.
+(It can't do this because it doesn't know
+whether these buffers were allocated dynamically.)
+If these buffers need to be freed (perhaps because the program
+is repeatedly creating and destroying hash tables,
+rather than creating a single table whose lifetime
+matches that of the program),
+then the program must maintain bookkeeping data structures that
+allow it to free them.
+.SH BUGS
+SVr4 and POSIX.1-2001 specify that \fIaction\fP
+is significant only for unsuccessful searches, so that an \fBENTER\fP
+should not do anything for a successful search.
+In libc and glibc (before glibc 2.3), the
+implementation violates the specification,
+updating the \fIdata\fP for the given \fIkey\fP in this case.
+.P
+Individual hash table entries can be added, but not deleted.
+.SH EXAMPLES
+The following program inserts 24 items into a hash table, then prints
+some of them.
+.P
+.\" SRC BEGIN (hsearch.c)
+.EX
+#include <search.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+static char *data[] = { "alpha", "bravo", "charlie", "delta",
+     "echo", "foxtrot", "golf", "hotel", "india", "juliet",
+     "kilo", "lima", "mike", "november", "oscar", "papa",
+     "quebec", "romeo", "sierra", "tango", "uniform",
+     "victor", "whisky", "x\-ray", "yankee", "zulu"
+};
+\&
+int
+main(void)
+{
+    ENTRY e;
+    ENTRY *ep;
+\&
+    hcreate(30);
+\&
+    for (size_t i = 0; i < 24; i++) {
+        e.key = data[i];
+        /* data is just an integer, instead of a
+           pointer to something */
+        e.data = (void *) i;
+        ep = hsearch(e, ENTER);
+        /* there should be no failures */
+        if (ep == NULL) {
+            fprintf(stderr, "entry failed\en");
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    for (size_t i = 22; i < 26; i++) {
+        /* print two entries from the table, and
+           show that two are not in the table */
+        e.key = data[i];
+        ep = hsearch(e, FIND);
+        printf("%9.9s \-> %9.9s:%d\en", e.key,
+               ep ? ep\->key : "NULL", ep ? (int)(ep\->data) : 0);
+    }
+    hdestroy();
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR bsearch (3),
+.BR lsearch (3),
+.BR malloc (3),
+.BR tsearch (3)
diff --git a/man/man3/hsearch_r.3 b/man/man3/hsearch_r.3
new file mode 100644
index 000000000..f4a0405da
--- /dev/null
+++ b/man/man3/hsearch_r.3
@@ -0,0 +1 @@
+.so man3/hsearch.3
diff --git a/man/man3/hstrerror.3 b/man/man3/hstrerror.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/hstrerror.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/htobe16.3 b/man/man3/htobe16.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/htobe16.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/htobe32.3 b/man/man3/htobe32.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/htobe32.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/htobe64.3 b/man/man3/htobe64.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/htobe64.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/htole16.3 b/man/man3/htole16.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/htole16.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/htole32.3 b/man/man3/htole32.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/htole32.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/htole64.3 b/man/man3/htole64.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/htole64.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/htonl.3 b/man/man3/htonl.3
new file mode 100644
index 000000000..ba374e841
--- /dev/null
+++ b/man/man3/htonl.3
@@ -0,0 +1 @@
+.so man3/byteorder.3
diff --git a/man/man3/htons.3 b/man/man3/htons.3
new file mode 100644
index 000000000..ba374e841
--- /dev/null
+++ b/man/man3/htons.3
@@ -0,0 +1 @@
+.so man3/byteorder.3
diff --git a/man/man3/hypot.3 b/man/man3/hypot.3
new file mode 100644
index 000000000..3c82980c1
--- /dev/null
+++ b/man/man3/hypot.3
@@ -0,0 +1,155 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH hypot 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hypot, hypotf, hypotl \- Euclidean distance function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double hypot(double " x ", double " y );
+.BI "float hypotf(float " x ", float " y );
+.BI "long double hypotl(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR hypot ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR hypotf (),
+.BR hypotl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return
+.RI sqrt( x * x + y * y ).
+This is the length of the hypotenuse of a right-angled triangle
+with sides of length
+.I x
+and
+.IR y ,
+or the distance of the point
+.RI ( x , y )
+from the origin.
+.P
+The calculation is performed without undue overflow or underflow
+during the intermediate steps of the calculation.
+.\" e.g., hypot(DBL_MIN, DBL_MIN) does the right thing, as does, say
+.\" hypot(DBL_MAX/2.0, DBL_MAX/2.0).
+.SH RETURN VALUE
+On success, these functions return the length of the hypotenuse of
+a right-angled triangle
+with sides of length
+.I x
+and
+.IR y .
+.P
+If
+.I x
+or
+.I y
+is an infinity,
+positive infinity is returned.
+.P
+If
+.I x
+or
+.I y
+is a NaN,
+and the other argument is not an infinity,
+a NaN is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively.
+.P
+If both arguments are subnormal, and the result is subnormal,
+.\" Actually, could the result not be subnormal if both arguments
+.\" are subnormal?  I think not -- mtk, Jul 2008
+a range error occurs,
+and the correct result is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error: result underflow
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.IP
+These functions do not set
+.I errno
+for this case.
+.\" This is intentional; see
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6795
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR hypot (),
+.BR hypotf (),
+.BR hypotl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR cabs (3),
+.BR sqrt (3)
diff --git a/man/man3/hypotf.3 b/man/man3/hypotf.3
new file mode 100644
index 000000000..e5c8ab887
--- /dev/null
+++ b/man/man3/hypotf.3
@@ -0,0 +1 @@
+.so man3/hypot.3
diff --git a/man/man3/hypotl.3 b/man/man3/hypotl.3
new file mode 100644
index 000000000..e5c8ab887
--- /dev/null
+++ b/man/man3/hypotl.3
@@ -0,0 +1 @@
+.so man3/hypot.3
diff --git a/man/man3/iconv.3 b/man/man3/iconv.3
new file mode 100644
index 000000000..12bb9b50b
--- /dev/null
+++ b/man/man3/iconv.3
@@ -0,0 +1,233 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   OpenGroup's Single UNIX specification
+.\"	http://www.UNIX-systems.org/online.html
+.\"
+.\" 2000-06-30 correction by Yuichi SATO <sato@complex.eng.hokudai.ac.jp>
+.\" 2000-11-15 aeb, fixed prototype
+.\"
+.TH iconv 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iconv \- perform character set conversion
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <iconv.h>
+.P
+.BI "size_t iconv(iconv_t " cd ,
+.BI "             char **restrict " inbuf ", size_t *restrict " inbytesleft ,
+.BI "             char **restrict " outbuf ", size_t *restrict " outbytesleft );
+.fi
+.SH DESCRIPTION
+The
+.BR iconv ()
+function converts a sequence of characters in one character encoding
+to a sequence of characters in another character encoding.
+The
+.I cd
+argument is a conversion descriptor,
+previously created by a call to
+.BR iconv_open (3);
+the conversion descriptor defines the character encodings that
+.BR iconv ()
+uses for the conversion.
+The
+.I inbuf
+argument is the address of a variable that points to
+the first character of the input sequence;
+.I inbytesleft
+indicates the number of bytes in that buffer.
+The
+.I outbuf
+argument is the address of a variable that points to
+the first byte available in the output buffer;
+.I outbytesleft
+indicates the number of bytes available in the output buffer.
+.P
+The main case is when \fIinbuf\fP is not NULL and \fI*inbuf\fP is not NULL.
+In this case, the
+.BR iconv ()
+function converts the multibyte sequence
+starting at \fI*inbuf\fP to a multibyte sequence starting at \fI*outbuf\fP.
+At most \fI*inbytesleft\fP bytes, starting at \fI*inbuf\fP, will be read.
+At most \fI*outbytesleft\fP bytes, starting at \fI*outbuf\fP, will be written.
+.P
+The
+.BR iconv ()
+function converts one multibyte character at a time, and for
+each character conversion it increments \fI*inbuf\fP and decrements
+\fI*inbytesleft\fP by the number of converted input bytes, it increments
+\fI*outbuf\fP and decrements \fI*outbytesleft\fP by the number of converted
+output bytes, and it updates the conversion state contained in \fIcd\fP.
+If the character encoding of the input is stateful, the
+.BR iconv ()
+function can also convert a sequence of input bytes
+to an update to the conversion state without producing any output bytes;
+such input is called a \fIshift sequence\fP.
+The conversion can stop for five reasons:
+.IP \[bu] 3
+An invalid multibyte sequence is encountered in the input.
+In this case,
+it sets \fIerrno\fP to \fBEILSEQ\fP and returns
+.IR (size_t)\ \-1 .
+\fI*inbuf\fP
+is left pointing to the beginning of the invalid multibyte sequence.
+.IP \[bu]
+A multibyte sequence is encountered that is valid but that
+cannot be translated to the character encoding of the output.
+This condition depends on the implementation and on the conversion descriptor.
+In the GNU C library and GNU libiconv, if
+.I cd
+was created without the suffix
+.B //TRANSLIT
+or
+.BR //IGNORE ,
+the conversion is strict:
+lossy conversions produce this condition.
+If the suffix
+.B //TRANSLIT
+was specified,
+transliteration can avoid this condition in some cases.
+In the musl C library,
+this condition cannot occur because a conversion to
+.B \[aq]*\[aq]
+is used as a fallback.
+In the FreeBSD, NetBSD, and Solaris implementations of
+.BR iconv (),
+this condition cannot occur either,
+because a conversion to
+.B \[aq]?\[aq]
+is used as a fallback.
+When this condition is met,
+.BR iconv ()
+sets
+.I errno
+to
+.B EILSEQ
+and returns
+.IR (size_t)\ \-1 .
+.I *inbuf
+is left pointing to the beginning of the unconvertible multibyte sequence.
+.IP \[bu]
+The input byte sequence has been entirely converted,
+that is, \fI*inbytesleft\fP has gone down to 0.
+In this case,
+.BR iconv ()
+returns the number of
+nonreversible conversions performed during this call.
+.IP \[bu]
+An incomplete multibyte sequence is encountered in the input, and the
+input byte sequence terminates after it.
+In this case, it sets \fIerrno\fP to
+\fBEINVAL\fP and returns
+.IR (size_t)\ \-1 .
+\fI*inbuf\fP is left pointing to the
+beginning of the incomplete multibyte sequence.
+.IP \[bu]
+The output buffer has no more room for the next converted character.
+In this case, it sets \fIerrno\fP to \fBE2BIG\fP and returns
+.IR (size_t)\ \-1 .
+.P
+A different case is when \fIinbuf\fP is NULL or \fI*inbuf\fP is NULL, but
+\fIoutbuf\fP is not NULL and \fI*outbuf\fP is not NULL.
+In this case, the
+.BR iconv ()
+function attempts to set \fIcd\fP's conversion state to the
+initial state and store a corresponding shift sequence at \fI*outbuf\fP.
+At most \fI*outbytesleft\fP bytes, starting at \fI*outbuf\fP, will be written.
+If the output buffer has no more room for this reset sequence, it sets
+\fIerrno\fP to \fBE2BIG\fP and returns
+.IR (size_t)\ \-1 .
+Otherwise, it increments
+\fI*outbuf\fP and decrements \fI*outbytesleft\fP by the number of bytes
+written.
+.P
+A third case is when \fIinbuf\fP is NULL or \fI*inbuf\fP is NULL, and
+\fIoutbuf\fP is NULL or \fI*outbuf\fP is NULL.
+In this case, the
+.BR iconv ()
+function sets \fIcd\fP's conversion state to the initial state.
+.SH RETURN VALUE
+The
+.BR iconv ()
+function returns the number of characters converted in a
+nonreversible way during this call; reversible conversions are not counted.
+In case of error,
+.BR iconv ()
+returns
+.I (size_t)\ \-1
+and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+The following errors can occur, among others:
+.TP
+.B E2BIG
+There is not sufficient room at \fI*outbuf\fP.
+.TP
+.B EILSEQ
+An invalid multibyte sequence has been encountered in the input.
+.TP
+.B EINVAL
+An incomplete multibyte sequence has been encountered in the input.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iconv ()
+T}	Thread safety	MT-Safe race:cd
+.TE
+.P
+The
+.BR iconv ()
+function is MT-Safe, as long as callers arrange for
+mutual exclusion on the
+.I cd
+argument.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH NOTES
+In each series of calls to
+.BR iconv (),
+the last should be one with \fIinbuf\fP or \fI*inbuf\fP equal to NULL,
+in order to flush out any partially converted input.
+.P
+Although
+.I inbuf
+and
+.I outbuf
+are typed as
+.IR "char\ **" ,
+this does not mean that the objects they point can be interpreted
+as C strings or as arrays of characters:
+the interpretation of character byte sequences is
+handled internally by the conversion functions.
+In some encodings, a zero byte may be a valid part of a multibyte character.
+.P
+The caller of
+.BR iconv ()
+must ensure that the pointers passed to the function are suitable
+for accessing characters in the appropriate character set.
+This includes ensuring correct alignment on platforms that have
+tight restrictions on alignment.
+.SH SEE ALSO
+.BR iconv_close (3),
+.BR iconv_open (3),
+.BR iconvconfig (8)
diff --git a/man/man3/iconv_close.3 b/man/man3/iconv_close.3
new file mode 100644
index 000000000..e3dc87e8a
--- /dev/null
+++ b/man/man3/iconv_close.3
@@ -0,0 +1,56 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH iconv_close 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iconv_close \- deallocate descriptor for character set conversion
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <iconv.h>
+.P
+.BI "int iconv_close(iconv_t " cd );
+.fi
+.SH DESCRIPTION
+The
+.BR iconv_close ()
+function deallocates a conversion descriptor
+.I cd
+previously allocated using
+.BR iconv_open (3).
+.SH RETURN VALUE
+On success,
+.BR iconv_close ()
+returns 0; otherwise, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iconv_close ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH SEE ALSO
+.BR iconv (3),
+.BR iconv_open (3)
diff --git a/man/man3/iconv_open.3 b/man/man3/iconv_open.3
new file mode 100644
index 000000000..f58629aee
--- /dev/null
+++ b/man/man3/iconv_open.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   OpenGroup's Single UNIX specification
+.\"     http://www.UNIX-systems.org/online.html
+.\"
+.\" 2007-03-31 Bruno Haible, Describe the glibc/libiconv //TRANSLIT
+.\" and //IGNORE extensions for 'tocode'.
+.\"
+.TH iconv_open 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iconv_open \- allocate descriptor for character set conversion
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <iconv.h>
+.P
+.BI "iconv_t iconv_open(const char *" tocode ", const char *" fromcode );
+.fi
+.SH DESCRIPTION
+The
+.BR iconv_open ()
+function allocates a conversion descriptor suitable
+for converting byte sequences from character encoding
+.I fromcode
+to
+character encoding
+.IR tocode .
+.P
+The values permitted for
+.I fromcode
+and
+.I tocode
+and the supported
+combinations are system-dependent.
+For the GNU C library, the permitted
+values are listed by the
+.I "iconv \-\-list"
+command, and all combinations
+of the listed values are supported.
+Furthermore the GNU C library and the
+GNU libiconv library support the following two suffixes:
+.TP
+//TRANSLIT
+When the string "//TRANSLIT" is appended to
+.IR tocode ,
+transliteration
+is activated.
+This means that when a character cannot be represented in the
+target character set, it can be approximated through one or several
+similarly looking characters.
+.TP
+//IGNORE
+When the string "//IGNORE" is appended to
+.IR tocode ,
+characters that
+cannot be represented in the target character set will be silently discarded.
+.P
+The resulting conversion descriptor can be used with
+.BR iconv (3)
+any number of times.
+It remains valid until deallocated using
+.BR iconv_close (3).
+.P
+A conversion descriptor contains a conversion state.
+After creation using
+.BR iconv_open (),
+the state is in the initial state.
+Using
+.BR iconv (3)
+modifies the descriptor's conversion state.
+To bring the state back to the initial state, use
+.BR iconv (3)
+with NULL as
+.I inbuf
+argument.
+.SH RETURN VALUE
+On success,
+.BR iconv_open ()
+returns a freshly allocated conversion
+descriptor.
+On failure, it returns
+.I (iconv_t)\ \-1
+and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+The following error can occur, among others:
+.TP
+.B EINVAL
+The conversion from
+.I fromcode
+to
+.I tocode
+is not supported by the
+implementation.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iconv_open ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001, SUSv2.
+.SH SEE ALSO
+.BR iconv (1),
+.BR iconv (3),
+.BR iconv_close (3)
diff --git a/man/man3/if_freenameindex.3 b/man/man3/if_freenameindex.3
new file mode 100644
index 000000000..d8aac8484
--- /dev/null
+++ b/man/man3/if_freenameindex.3
@@ -0,0 +1 @@
+.so man3/if_nameindex.3
diff --git a/man/man3/if_indextoname.3 b/man/man3/if_indextoname.3
new file mode 100644
index 000000000..437965929
--- /dev/null
+++ b/man/man3/if_indextoname.3
@@ -0,0 +1 @@
+.so man3/if_nametoindex.3
diff --git a/man/man3/if_nameindex.3 b/man/man3/if_nameindex.3
new file mode 100644
index 000000000..32afb1763
--- /dev/null
+++ b/man/man3/if_nameindex.3
@@ -0,0 +1,154 @@
+'\" t
+.\" Copyright (c) 2012 YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+.\" and Copyright (c) 2012 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH if_nameindex 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+if_nameindex, if_freenameindex \- get network interface names and indexes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <net/if.h>
+.P
+.BI "struct if_nameindex *if_nameindex(" void );
+.BI "void if_freenameindex(struct if_nameindex *" "ptr" );
+.fi
+.SH DESCRIPTION
+The
+.BR if_nameindex ()
+function returns an array of
+.I if_nameindex
+structures, each containing information
+about one of the network interfaces on the local system.
+The
+.I if_nameindex
+structure contains at least the following entries:
+.P
+.in +4n
+.EX
+unsigned int if_index; /* Index of interface (1, 2, ...) */
+char        *if_name;  /* Null\-terminated name ("eth0", etc.) */
+.EE
+.in
+.P
+The
+.I if_index
+field contains the interface index.
+The
+.I if_name
+field points to the null-terminated interface name.
+The end of the array is indicated by entry with
+.I if_index
+set to zero and
+.I if_name
+set to NULL.
+.P
+The data structure returned by
+.BR if_nameindex ()
+is dynamically allocated and should be freed using
+.BR if_freenameindex ()
+when no longer needed.
+.SH RETURN VALUE
+On success,
+.BR if_nameindex ()
+returns pointer to the array;
+on error, NULL is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR if_nameindex ()
+may fail and set
+.I errno
+if:
+.TP
+.B ENOBUFS
+Insufficient resources available.
+.P
+.BR if_nameindex ()
+may also fail for any of the errors specified for
+.BR socket (2),
+.BR bind (2),
+.BR ioctl (2),
+.BR getsockname (2),
+.BR recvmsg (2),
+.BR sendto (2),
+or
+.BR malloc (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR if_nameindex (),
+.BR if_freenameindex ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008, RFC\ 3493.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+BSDi.
+.P
+Before glibc 2.3.4,
+the implementation supported only interfaces with IPv4 addresses.
+Support of interfaces that don't have IPv4 addresses is available only
+on kernels that support netlink.
+.SH EXAMPLES
+The program below demonstrates the use of the functions described
+on this page.
+An example of the output this program might produce is the following:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fI
+1: lo
+2: wlan0
+3: em1
+.EE
+.in
+.SS Program source
+.\" SRC BEGIN (if_nameindex.c)
+.EX
+#include <net/if.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+int
+main(void)
+{
+    struct if_nameindex *if_ni, *i;
+\&
+    if_ni = if_nameindex();
+    if (if_ni == NULL) {
+        perror("if_nameindex");
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (i = if_ni; !(i\->if_index == 0 && i\->if_name == NULL); i++)
+        printf("%u: %s\en", i\->if_index, i\->if_name);
+\&
+    if_freenameindex(if_ni);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getsockopt (2),
+.BR setsockopt (2),
+.BR getifaddrs (3),
+.BR if_indextoname (3),
+.BR if_nametoindex (3),
+.BR ifconfig (8)
diff --git a/man/man3/if_nametoindex.3 b/man/man3/if_nametoindex.3
new file mode 100644
index 000000000..5ca0514ed
--- /dev/null
+++ b/man/man3/if_nametoindex.3
@@ -0,0 +1,99 @@
+'\" t
+.\" Copyright (c) 2012 YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH if_nametoindex 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+if_nametoindex, if_indextoname \- mappings between network interface
+names and indexes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <net/if.h>
+.P
+.BI "unsigned int if_nametoindex(const char *" "ifname" );
+.BI "char *if_indextoname(unsigned int ifindex, char *" ifname );
+.fi
+.SH DESCRIPTION
+The
+.BR if_nametoindex ()
+function returns the index of the network interface
+corresponding to the name
+.IR ifname .
+.P
+The
+.BR if_indextoname ()
+function returns the name of the network interface
+corresponding to the interface index
+.IR ifindex .
+The name is placed in the buffer pointed to by
+.IR ifname .
+The buffer must allow for the storage of at least
+.B IF_NAMESIZE
+bytes.
+.SH RETURN VALUE
+On success,
+.BR if_nametoindex ()
+returns the index number of the network interface;
+on error, 0 is returned and
+.I errno
+is set to indicate the error.
+.P
+On success,
+.BR if_indextoname ()
+returns
+.IR ifname ;
+on error, NULL is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.BR if_nametoindex ()
+may fail and set
+.I errno
+if:
+.TP
+.B ENODEV
+No interface found with given name.
+.P
+.BR if_indextoname ()
+may fail and set
+.I errno
+if:
+.TP
+.B ENXIO
+No interface found for the index.
+.P
+.BR if_nametoindex ()
+and
+.BR if_indextoname ()
+may also fail for any of the errors specified for
+.BR socket (2)
+or
+.BR ioctl (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR if_nametoindex (),
+.BR if_indextoname ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008, RFC\ 3493.
+.SH HISTORY
+POSIX.1-2001.
+BSDi.
+.SH SEE ALSO
+.BR getifaddrs (3),
+.BR if_nameindex (3),
+.BR ifconfig (8)
diff --git a/man/man3/ilogb.3 b/man/man3/ilogb.3
new file mode 100644
index 000000000..5130e40e0
--- /dev/null
+++ b/man/man3/ilogb.3
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Inspired by a page by Walter Harms created 2002-08-10
+.\"
+.TH ilogb 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ilogb, ilogbf, ilogbl \- get integer exponent of a floating-point value
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "int ilogb(double " x );
+.BI "int ilogbf(float " x );
+.BI "int ilogbl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ilogb ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR ilogbf (),
+.BR ilogbl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the exponent part of their argument
+as a signed integer.
+When no error occurs, these functions
+are equivalent to the corresponding
+.BR logb (3)
+functions, cast to
+.IR int .
+.SH RETURN VALUE
+On success, these functions return the exponent of
+.IR x ,
+as a signed integer.
+.P
+If
+.I x
+is zero, then a domain error occurs, and the functions return
+.\" the POSIX.1 spec for logb() says logb() gives pole error for this
+.\" case, but for ilogb() it says domain error.
+.BR FP_ILOGB0 .
+.\" glibc: The numeric value is either `INT_MIN' or `-INT_MAX'.
+.P
+If
+.I x
+is a NaN, then a domain error occurs, and the functions return
+.BR FP_ILOGBNAN .
+.\" glibc: The numeric value is either `INT_MIN' or `INT_MAX'.
+.\" On i386, FP_ILOGB0 and FP_ILOGBNAN have the same value.
+.P
+If
+.I x
+is negative infinity or positive infinity, then
+a domain error occurs, and the functions return
+.BR INT_MAX .
+.\"
+.\" POSIX.1-2001 also says:
+.\" If the correct value is greater than {INT_MAX}, {INT_MAX}
+.\" shall be returned and a domain error shall occur.
+.\"
+.\" If the correct value is less than {INT_MIN}, {INT_MIN}
+.\" shall be returned and a domain error shall occur.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is 0 or a NaN
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised, and
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+.TP
+Domain error: \fIx\fP is an infinity
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised, and
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ilogb (),
+.BR ilogbf (),
+.BR ilogbl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH BUGS
+.\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6794
+Before glibc 2.16, the following bugs existed in the
+glibc implementation of these functions:
+.IP \[bu] 3
+The domain error case where
+.I x
+is 0 or a NaN did not cause
+.I errno
+to be set or (on some architectures) raise a floating-point exception.
+.IP \[bu]
+The domain error case where
+.I x
+is an infinity did not cause
+.I errno
+to be set or raise a floating-point exception.
+.SH SEE ALSO
+.BR log (3),
+.BR logb (3),
+.BR significand (3)
diff --git a/man/man3/ilogbf.3 b/man/man3/ilogbf.3
new file mode 100644
index 000000000..213d00afa
--- /dev/null
+++ b/man/man3/ilogbf.3
@@ -0,0 +1 @@
+.so man3/ilogb.3
diff --git a/man/man3/ilogbl.3 b/man/man3/ilogbl.3
new file mode 100644
index 000000000..213d00afa
--- /dev/null
+++ b/man/man3/ilogbl.3
@@ -0,0 +1 @@
+.so man3/ilogb.3
diff --git a/man/man3/imaxabs.3 b/man/man3/imaxabs.3
new file mode 100644
index 000000000..97db8d2b6
--- /dev/null
+++ b/man/man3/imaxabs.3
@@ -0,0 +1 @@
+.so man3/abs.3
diff --git a/man/man3/imaxdiv.3 b/man/man3/imaxdiv.3
new file mode 100644
index 000000000..934824e3e
--- /dev/null
+++ b/man/man3/imaxdiv.3
@@ -0,0 +1 @@
+.so man3/div.3
diff --git a/man/man3/index.3 b/man/man3/index.3
new file mode 100644
index 000000000..a47ce0dae
--- /dev/null
+++ b/man/man3/index.3
@@ -0,0 +1,44 @@
+.\" Copyright 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH index 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+index, rindex \- locate character in string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <strings.h>
+.P
+.BI "[[deprecated]] char *index(const char *" s ", int " c );
+.BI "[[deprecated]] char *rindex(const char *" s ", int " c );
+.fi
+.SH DESCRIPTION
+.BR index ()
+is identical to
+.BR strchr (3).
+.P
+.BR rindex ()
+is identical to
+.BR strrchr (3).
+.P
+Use
+.BR strchr (3)
+and
+.BR strrchr (3)
+instead of these functions.
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD; marked as LEGACY in POSIX.1-2001.
+Removed in POSIX.1-2008,
+recommending
+.BR strchr (3)
+and
+.BR strrchr (3)
+instead.
+.SH SEE ALSO
+.BR strchr (3),
+.BR strrchr (3)
diff --git a/man/man3/inet.3 b/man/man3/inet.3
new file mode 100644
index 000000000..9e292f08a
--- /dev/null
+++ b/man/man3/inet.3
@@ -0,0 +1,336 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"     libc.info (from glibc distribution)
+.\" Modified Sat Jul 24 19:12:00 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Sep  3 20:29:36 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" Changed network into host byte order (for inet_network),
+.\"     Andreas Jaeger <aj@arthur.rhein-neckar.de>, 980130.
+.\" 2008-06-19, mtk
+.\"     Describe the various address forms supported by inet_aton().
+.\"     Clarify discussion of inet_lnaof(), inet_netof(), and inet_makeaddr().
+.\"     Add discussion of Classful Addressing, noting that it is obsolete.
+.\"     Added an EXAMPLE program.
+.\"
+.TH inet 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inet_aton, inet_addr, inet_network, inet_ntoa, inet_makeaddr, inet_lnaof,
+inet_netof \- Internet address manipulation routines
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <netinet/in.h>
+.B #include <arpa/inet.h>
+.P
+.BI "int inet_aton(const char *" cp ", struct in_addr *" inp );
+.P
+.BI "in_addr_t inet_addr(const char *" cp );
+.BI "in_addr_t inet_network(const char *" cp );
+.P
+.BI "[[deprecated]] char *inet_ntoa(struct in_addr " in );
+.P
+.BI "[[deprecated]] struct in_addr inet_makeaddr(in_addr_t " net ,
+.BI "                                            in_addr_t " host );
+.P
+.BI "[[deprecated]] in_addr_t inet_lnaof(struct in_addr " in );
+.BI "[[deprecated]] in_addr_t inet_netof(struct in_addr " in );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR inet_aton (),
+.BR inet_ntoa ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    In glibc up to and including 2.19:
+        _BSD_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR inet_aton ()
+converts the Internet host address \fIcp\fP from the
+IPv4 numbers-and-dots notation into binary form (in network byte order)
+and stores it in the structure that \fIinp\fP points to.
+.BR inet_aton ()
+returns nonzero if the address is valid, zero if not.
+The address supplied in
+.I cp
+can have one of the following forms:
+.TP 10
+.I a.b.c.d
+Each of the four numeric parts specifies a byte of the address;
+the bytes are assigned in left-to-right order to produce the binary address.
+.TP
+.I a.b.c
+Parts
+.I a
+and
+.I b
+specify the first two bytes of the binary address.
+Part
+.I c
+is interpreted as a 16-bit value that defines the rightmost two bytes
+of the binary address.
+This notation is suitable for specifying (outmoded) Class B
+network addresses.
+.TP
+.I a.b
+Part
+.I a
+specifies the first byte of the binary address.
+Part
+.I b
+is interpreted as a 24-bit value that defines the rightmost three bytes
+of the binary address.
+This notation is suitable for specifying (outmoded) Class A
+network addresses.
+.TP
+.I a
+The value
+.I a
+is interpreted as a 32-bit value that is stored directly
+into the binary address without any byte rearrangement.
+.P
+In all of the above forms,
+components of the dotted address can be specified in decimal,
+octal (with a leading
+.IR 0 ),
+or hexadecimal, with a leading
+.IR 0X ).
+Addresses in any of these forms are collectively termed
+.IR "IPV4 numbers-and-dots notation" .
+The form that uses exactly four decimal numbers is referred to as
+.I IPv4 dotted-decimal notation
+(or sometimes:
+.IR "IPv4 dotted-quad notation" ).
+.P
+.BR inet_aton ()
+returns 1 if the supplied string was successfully interpreted,
+or 0 if the string is invalid
+.RB ( errno
+is
+.I not
+set on error).
+.P
+The
+.BR inet_addr ()
+function converts the Internet host address
+\fIcp\fP from IPv4 numbers-and-dots notation into binary data in network
+byte order.
+If the input is invalid,
+.B INADDR_NONE
+(usually \-1) is returned.
+Use of this function is problematic because \-1 is a valid address
+(255.255.255.255).
+Avoid its use in favor of
+.BR inet_aton (),
+.BR inet_pton (3),
+or
+.BR getaddrinfo (3),
+which provide a cleaner way to indicate error return.
+.P
+The
+.BR inet_network ()
+function converts
+.IR cp ,
+a string in IPv4 numbers-and-dots notation,
+into a number in host byte order suitable for use as an
+Internet network address.
+On success, the converted address is returned.
+If the input is invalid, \-1 is returned.
+.P
+The
+.BR inet_ntoa ()
+function converts the Internet host address
+\fIin\fP, given in network byte order, to a string in IPv4
+dotted-decimal notation.
+The string is returned in a statically
+allocated buffer, which subsequent calls will overwrite.
+.P
+The
+.BR inet_lnaof ()
+function returns the local network address part
+of the Internet address \fIin\fP.
+The returned value is in host byte order.
+.P
+The
+.BR inet_netof ()
+function returns the network number part of
+the Internet address \fIin\fP.
+The returned value is in host byte order.
+.P
+The
+.BR inet_makeaddr ()
+function is the converse of
+.BR inet_netof ()
+and
+.BR inet_lnaof ().
+It returns an Internet host address in network byte order,
+created by combining the network number \fInet\fP
+with the local address \fIhost\fP, both in
+host byte order.
+.P
+The structure \fIin_addr\fP as used in
+.BR inet_ntoa (),
+.BR inet_makeaddr (),
+.BR inet_lnaof (),
+and
+.BR inet_netof ()
+is defined in
+.I <netinet/in.h>
+as:
+.P
+.in +4n
+.EX
+typedef uint32_t in_addr_t;
+\&
+struct in_addr {
+    in_addr_t s_addr;
+};
+.EE
+.in
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR inet_aton (),
+.BR inet_addr (),
+.BR inet_network (),
+.BR inet_ntoa ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR inet_makeaddr (),
+.BR inet_lnaof (),
+.BR inet_netof ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR inet_addr ()
+.TQ
+.BR inet_ntoa ()
+POSIX.1-2008.
+.TP
+.BR inet_aton ()
+None.
+.SH STANDARDS
+.TP
+.BR inet_addr ()
+.TQ
+.BR inet_ntoa ()
+POSIX.1-2001, 4.3BSD.
+.P
+.BR inet_lnaof (),
+.BR inet_netof (),
+and
+.BR inet_makeaddr ()
+are legacy functions that assume they are dealing with
+.IR "classful network addresses" .
+Classful networking divides IPv4 network addresses into host and network
+components at byte boundaries, as follows:
+.TP 10
+Class A
+This address type is indicated by the value 0 in the
+most significant bit of the (network byte ordered) address.
+The network address is contained in the most significant byte,
+and the host address occupies the remaining three bytes.
+.TP
+Class B
+This address type is indicated by the binary value 10 in the
+most significant two bits of the address.
+The network address is contained in the two most significant bytes,
+and the host address occupies the remaining two bytes.
+.TP
+Class C
+This address type is indicated by the binary value 110 in the
+most significant three bits of the address.
+The network address is contained in the three most significant bytes,
+and the host address occupies the remaining byte.
+.P
+Classful network addresses are now obsolete,
+having been superseded by Classless Inter-Domain Routing (CIDR),
+which divides addresses into network and host components at
+arbitrary bit (rather than byte) boundaries.
+.SH NOTES
+On x86 architectures, the host byte order is Least Significant Byte
+first (little endian), whereas the network byte order, as used on the
+Internet, is Most Significant Byte first (big endian).
+.SH EXAMPLES
+An example of the use of
+.BR inet_aton ()
+and
+.BR inet_ntoa ()
+is shown below.
+Here are some example runs:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 226.000.000.037" "      # Last byte is in octal"
+226.0.0.31
+.RB "$" " ./a.out 0x7f.1         " "      # First byte is in hex"
+127.0.0.1
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (inet.c)
+.EX
+#define _DEFAULT_SOURCE
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    struct in_addr addr;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "%s <dotted\-address>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (inet_aton(argv[1], &addr) == 0) {
+        fprintf(stderr, "Invalid address\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("%s\en", inet_ntoa(addr));
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR byteorder (3),
+.BR getaddrinfo (3),
+.BR gethostbyname (3),
+.BR getnameinfo (3),
+.BR getnetent (3),
+.BR inet_net_pton (3),
+.BR inet_ntop (3),
+.BR inet_pton (3),
+.BR hosts (5),
+.BR networks (5)
diff --git a/man/man3/inet_addr.3 b/man/man3/inet_addr.3
new file mode 100644
index 000000000..0eba30eb9
--- /dev/null
+++ b/man/man3/inet_addr.3
@@ -0,0 +1 @@
+.so man3/inet.3
diff --git a/man/man3/inet_aton.3 b/man/man3/inet_aton.3
new file mode 100644
index 000000000..0eba30eb9
--- /dev/null
+++ b/man/man3/inet_aton.3
@@ -0,0 +1 @@
+.so man3/inet.3
diff --git a/man/man3/inet_lnaof.3 b/man/man3/inet_lnaof.3
new file mode 100644
index 000000000..0eba30eb9
--- /dev/null
+++ b/man/man3/inet_lnaof.3
@@ -0,0 +1 @@
+.so man3/inet.3
diff --git a/man/man3/inet_makeaddr.3 b/man/man3/inet_makeaddr.3
new file mode 100644
index 000000000..4a9e0fd11
--- /dev/null
+++ b/man/man3/inet_makeaddr.3
@@ -0,0 +1 @@
+.so man3/inet_addr.3
diff --git a/man/man3/inet_net_ntop.3 b/man/man3/inet_net_ntop.3
new file mode 100644
index 000000000..10b8d4473
--- /dev/null
+++ b/man/man3/inet_net_ntop.3
@@ -0,0 +1 @@
+.so man3/inet_net_pton.3
diff --git a/man/man3/inet_net_pton.3 b/man/man3/inet_net_pton.3
new file mode 100644
index 000000000..c66ee8257
--- /dev/null
+++ b/man/man3/inet_net_pton.3
@@ -0,0 +1,369 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH inet_net_pton 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inet_net_pton, inet_net_ntop \- Internet network number conversion
+.SH LIBRARY
+Resolver library
+.RI ( libresolv ", " \-lresolv )
+.SH SYNOPSIS
+.nf
+.B #include <arpa/inet.h>
+.P
+.BI "int inet_net_pton(int " af ", const char *" pres ,
+.BI "                  void " netp [. nsize "], size_t " nsize );
+.BI "char *inet_net_ntop(int " af ,
+.BI "                  const void " netp [(. bits " - CHAR_BIT + 1) / CHAR_BIT],"
+.BI "                  int " bits ,
+.BI "                  char " pres [. psize "], size_t " psize );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR inet_net_pton (),
+.BR inet_net_ntop ():
+.nf
+    Since glibc 2.20:
+        _DEFAULT_SOURCE
+    Before glibc 2.20:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions convert network numbers between
+presentation (i.e., printable) format and network (i.e., binary) format.
+.P
+For both functions,
+.I af
+specifies the address family for the conversion;
+the only supported value is
+.BR AF_INET .
+.SS inet_net_pton()
+The
+.BR inet_net_pton ()
+function converts
+.IR pres ,
+a null-terminated string containing an Internet network number in
+presentation format to network format.
+The result of the conversion, which is in network byte order,
+is placed in the buffer pointed to by
+.IR netp .
+(The
+.I netp
+argument typically points to an
+.I in_addr
+structure.)
+The
+.I nsize
+argument specifies the number of bytes available in
+.IR netp .
+.P
+On success,
+.BR inet_net_pton ()
+returns the number of bits in the network number field
+of the result placed in
+.IR netp .
+For a discussion of the input presentation format and the return value,
+see NOTES.
+.P
+.IR Note :
+the buffer pointed to by
+.I netp
+should be zeroed out before calling
+.BR inet_net_pton (),
+since the call writes only as many bytes as are required
+for the network number (or as are explicitly specified by
+.IR pres ),
+which may be less than the number of bytes in a complete network address.
+.SS inet_net_ntop()
+The
+.BR inet_net_ntop ()
+function converts the network number in the buffer pointed to by
+.I netp
+to presentation format;
+.I *netp
+is interpreted as a value in network byte order.
+The
+.I bits
+argument specifies the number of bits in the network number in
+.IR *netp .
+.P
+The null-terminated presentation-format string
+is placed in the buffer pointed to by
+.IR pres .
+The
+.I psize
+argument specifies the number of bytes available in
+.IR pres .
+The presentation string is in CIDR format:
+a dotted-decimal number representing the network address,
+followed by a slash, and the size of the network number in bits.
+.SH RETURN VALUE
+On success,
+.BR inet_net_pton ()
+returns the number of bits in the network number.
+On error, it returns \-1, and
+.I errno
+is set to indicate the error.
+.P
+On success,
+.BR inet_net_ntop ()
+returns
+.IR pres .
+On error, it returns NULL, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAFNOSUPPORT
+.I af
+specified a value other than
+.BR AF_INET .
+.TP
+.B EMSGSIZE
+The size of the output buffer was insufficient.
+.TP
+.B ENOENT
+.RB ( inet_net_pton ())
+.I pres
+was not in correct presentation format.
+.SH STANDARDS
+None.
+.SH NOTES
+.SS Input presentation format for inet_net_pton()
+The network number may be specified either
+as a hexadecimal value
+or in dotted-decimal notation.
+.P
+Hexadecimal values are indicated by an initial "0x" or "0X".
+The hexadecimal digits populate the nibbles (half octets) of the
+network number from left to right in network byte order.
+.\" If the hexadecimal string is short, the remaining nibbles are zeroed.
+.P
+In dotted-decimal notation, up to four octets are specified,
+as decimal numbers separated by dots.
+Thus, any of the following forms are accepted:
+.P
+.in +4n
+.EX
+a.b.c.d
+a.b.c
+a.b
+a
+.EE
+.in
+.P
+Each part is a number in the range 0 to 255 that
+populates one byte of the resulting network number,
+going from left to right, in network-byte (big endian) order.
+Where a part is omitted, the resulting byte in the network number is zero.
+.\" Reading other man pages, some other implementations treat
+.\" 	'c' in a.b.c as a 16-bit number that populates right-most two bytes
+.\"     'b' in a.b as a 24-bit number that populates right-most three bytes
+.P
+For either hexadecimal or dotted-decimal format,
+the network number can optionally be followed by a slash
+and a number in the range 0 to 32,
+which specifies the size of the network number in bits.
+.SS Return value of inet_net_pton()
+The return value of
+.BR inet_net_pton ()
+is the number of bits in the network number field.
+If the input presentation string terminates with a slash and
+an explicit size value, then that size becomes the return value of
+.BR inet_net_pton ().
+Otherwise, the return value,
+.IR bits ,
+is inferred as follows:
+.IP \[bu] 3
+If the most significant byte of the network number is
+greater than or equal to 240,
+then
+.I bits
+is 32.
+.IP \[bu]
+Otherwise,
+if the most significant byte of the network number is
+greater than or equal to 224,
+then
+.I bits
+is 4.
+.IP \[bu]
+Otherwise,
+if the most significant byte of the network number is
+greater than or equal to 192,
+then
+.I bits
+is 24.
+.IP \[bu]
+Otherwise,
+if the most significant byte of the network number is
+greater than or equal to 128,
+then
+.I bits
+is 16.
+.IP \[bu]
+Otherwise,
+.I bits
+is 8.
+.P
+If the resulting
+.I bits
+value from the above steps is greater than or equal to 8,
+but the number of octets specified in the network number exceed
+.IR "bits/8" ,
+then
+.I bits
+is set to 8 times the number of octets actually specified.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR inet_net_pton ()
+and
+.BR inet_net_ntop ().
+It uses
+.BR inet_net_pton ()
+to convert the presentation format network address provided in
+its first command-line argument to binary form, displays the return value from
+.BR inet_net_pton ().
+It then uses
+.BR inet_net_ntop ()
+to convert the binary form back to presentation format,
+and displays the resulting string.
+.P
+In order to demonstrate that
+.BR inet_net_pton ()
+may not write to all bytes of its
+.I netp
+argument, the program allows an optional second command-line argument,
+a number used to initialize the buffer before
+.BR inet_net_pton ()
+is called.
+As its final line of output,
+the program displays all of the bytes of the buffer returned by
+.BR inet_net_pton ()
+allowing the user to see which bytes have not been touched by
+.BR inet_net_pton ().
+.P
+An example run, showing that
+.BR inet_net_pton ()
+infers the number of bits in the network number:
+.P
+.in +4n
+.EX
+$ \fB./a.out 193.168\fP
+inet_net_pton() returned: 24
+inet_net_ntop() yielded:  193.168.0/24
+Raw address:              c1a80000
+.EE
+.in
+.P
+Demonstrate that
+.BR inet_net_pton ()
+does not zero out unused bytes in its result buffer:
+.P
+.in +4n
+.EX
+$ \fB./a.out 193.168 0xffffffff\fP
+inet_net_pton() returned: 24
+inet_net_ntop() yielded:  193.168.0/24
+Raw address:              c1a800ff
+.EE
+.in
+.P
+Demonstrate that
+.BR inet_net_pton ()
+will widen the inferred size of the network number,
+if the supplied number of bytes in the presentation
+string exceeds the inferred value:
+.P
+.in +4n
+.EX
+$ \fB./a.out 193.168.1.128\fP
+inet_net_pton() returned: 32
+inet_net_ntop() yielded:  193.168.1.128/32
+Raw address:              c1a80180
+.EE
+.in
+.P
+Explicitly specifying the size of the network number overrides any
+inference about its size
+(but any extra bytes that are explicitly specified will still be used by
+.BR inet_net_pton ():
+to populate the result buffer):
+.P
+.in +4n
+.EX
+$ \fB./a.out 193.168.1.128/24\fP
+inet_net_pton() returned: 24
+inet_net_ntop() yielded:  193.168.1/24
+Raw address:              c1a80180
+.EE
+.in
+.SS Program source
+.\" SRC BEGIN (inet_net_pton.c)
+.EX
+/* Link with "\-lresolv" */
+\&
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+int
+main(int argc, char *argv[])
+{
+    char buf[100];
+    struct in_addr addr;
+    int bits;
+\&
+    if (argc < 2) {
+        fprintf(stderr,
+                "Usage: %s presentation\-form [addr\-init\-value]\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* If argv[2] is supplied (a numeric value), use it to initialize
+       the output buffer given to inet_net_pton(), so that we can see
+       that inet_net_pton() initializes only those bytes needed for
+       the network number. If argv[2] is not supplied, then initialize
+       the buffer to zero (as is recommended practice). */
+\&
+    addr.s_addr = (argc > 2) ? strtod(argv[2], NULL) : 0;
+\&
+    /* Convert presentation network number in argv[1] to binary. */
+\&
+    bits = inet_net_pton(AF_INET, argv[1], &addr, sizeof(addr));
+    if (bits == \-1)
+        errExit("inet_net_ntop");
+\&
+    printf("inet_net_pton() returned: %d\en", bits);
+\&
+    /* Convert binary format back to presentation, using \[aq]bits\[aq]
+       returned by inet_net_pton(). */
+\&
+    if (inet_net_ntop(AF_INET, &addr, bits, buf, sizeof(buf)) == NULL)
+        errExit("inet_net_ntop");
+\&
+    printf("inet_net_ntop() yielded:  %s\en", buf);
+\&
+    /* Display \[aq]addr\[aq] in raw form (in network byte order), so we can
+       see bytes not displayed by inet_net_ntop(); some of those bytes
+       may not have been touched by inet_net_ntop(), and so will still
+       have any initial value that was specified in argv[2]. */
+\&
+    printf("Raw address:              %x\en", htonl(addr.s_addr));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR inet (3),
+.BR networks (5)
diff --git a/man/man3/inet_netof.3 b/man/man3/inet_netof.3
new file mode 100644
index 000000000..0eba30eb9
--- /dev/null
+++ b/man/man3/inet_netof.3
@@ -0,0 +1 @@
+.so man3/inet.3
diff --git a/man/man3/inet_network.3 b/man/man3/inet_network.3
new file mode 100644
index 000000000..0eba30eb9
--- /dev/null
+++ b/man/man3/inet_network.3
@@ -0,0 +1 @@
+.so man3/inet.3
diff --git a/man/man3/inet_ntoa.3 b/man/man3/inet_ntoa.3
new file mode 100644
index 000000000..0eba30eb9
--- /dev/null
+++ b/man/man3/inet_ntoa.3
@@ -0,0 +1 @@
+.so man3/inet.3
diff --git a/man/man3/inet_ntop.3 b/man/man3/inet_ntop.3
new file mode 100644
index 000000000..8926460d4
--- /dev/null
+++ b/man/man3/inet_ntop.3
@@ -0,0 +1,122 @@
+'\" t
+.\" Copyright 2000 Sam Varshavchik <mrsam@courier-mta.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References: RFC 2553
+.TH inet_ntop 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inet_ntop \- convert IPv4 and IPv6 addresses from binary to text form
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <arpa/inet.h>
+.P
+.BI "const char *inet_ntop(int " af ", const void *restrict " src ,
+.BI "                      char " dst "[restrict ." size "], socklen_t " size );
+.fi
+.SH DESCRIPTION
+This function converts the network address structure
+.I src
+in the
+.I af
+address family into a character string.
+The resulting string is copied to the buffer pointed to by
+.IR dst ,
+which must be a non-null pointer.
+The caller specifies the number of bytes available in this buffer in
+the argument
+.IR size .
+.P
+.BR inet_ntop ()
+extends the
+.BR inet_ntoa (3)
+function to support multiple address families,
+.BR inet_ntoa (3)
+is now considered to be deprecated in favor of
+.BR inet_ntop ().
+The following address families are currently supported:
+.TP
+.B AF_INET
+.I src
+points to a
+.I struct in_addr
+(in network byte order)
+which is converted to an IPv4 network address in
+the dotted-decimal format, "\fIddd.ddd.ddd.ddd\fP".
+The buffer
+.I dst
+must be at least
+.B INET_ADDRSTRLEN
+bytes long.
+.TP
+.B AF_INET6
+.I src
+points to a
+.I struct in6_addr
+(in network byte order)
+which is converted to a representation of this address in the
+most appropriate IPv6 network address format for this address.
+The buffer
+.I dst
+must be at least
+.B INET6_ADDRSTRLEN
+bytes long.
+.SH RETURN VALUE
+On success,
+.BR inet_ntop ()
+returns a non-null pointer to
+.IR dst .
+NULL is returned if there was an error, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EAFNOSUPPORT
+.I af
+was not a valid address family.
+.TP
+.B ENOSPC
+The converted address string would exceed the size given by
+.IR size .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR inet_ntop ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Note that RFC\ 2553 defines a prototype where the last argument
+.I size
+is of type
+.IR size_t .
+Many systems follow RFC\ 2553.
+glibc 2.0 and 2.1 have
+.IR size_t ,
+but 2.2 and later have
+.IR socklen_t .
+.\" 2.1.3: size_t, 2.1.91: socklen_t
+.SH BUGS
+.B AF_INET6
+converts IPv4-mapped IPv6 addresses into an IPv6 format.
+.SH EXAMPLES
+See
+.BR inet_pton (3).
+.SH SEE ALSO
+.BR getnameinfo (3),
+.BR inet (3),
+.BR inet_pton (3)
diff --git a/man/man3/inet_pton.3 b/man/man3/inet_pton.3
new file mode 100644
index 000000000..b92046e40
--- /dev/null
+++ b/man/man3/inet_pton.3
@@ -0,0 +1,223 @@
+'\" t
+.\" Copyright 2000 Sam Varshavchik <mrsam@courier-mta.com>
+.\" and Copyright (c) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References: RFC 2553
+.TH inet_pton 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inet_pton \- convert IPv4 and IPv6 addresses from text to binary form
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <arpa/inet.h>
+.P
+.BI "int inet_pton(int " af ", const char *restrict " src \
+", void *restrict " dst );
+.fi
+.SH DESCRIPTION
+This function converts the character string
+.I src
+into a network address structure in the
+.I af
+address family, then
+copies
+the network address structure to
+.IR dst .
+The
+.I af
+argument must be either
+.B AF_INET
+or
+.BR AF_INET6 .
+.I dst
+is written in network byte order.
+.P
+The following address families are currently supported:
+.TP
+.B AF_INET
+.I src
+points to a character string containing an IPv4 network address in
+dotted-decimal format, "\fIddd.ddd.ddd.ddd\fP", where
+.I ddd
+is a decimal number of up to three digits in the range 0 to 255.
+The address is converted to a
+.I struct in_addr
+and copied to
+.IR dst ,
+which must be
+.I sizeof(struct in_addr)
+(4) bytes (32 bits) long.
+.TP
+.B AF_INET6
+.I src
+points to a character string containing an IPv6 network address.
+The address is converted to a
+.I struct in6_addr
+and copied to
+.IR dst ,
+which must be
+.I sizeof(struct in6_addr)
+(16) bytes (128 bits) long.
+The allowed formats for IPv6 addresses follow these rules:
+.RS
+.IP \[bu] 3
+The preferred format is
+.IR x:x:x:x:x:x:x:x .
+This form consists of eight hexadecimal numbers,
+each of which expresses a 16-bit value (i.e., each
+.I x
+can be up to 4 hex digits).
+.IP \[bu]
+A series of contiguous zero values in the preferred format
+can be abbreviated to
+.IR :: .
+Only one instance of
+.I ::
+can occur in an address.
+For example, the loopback address
+.I 0:0:0:0:0:0:0:1
+can be abbreviated as
+.IR ::1 .
+The wildcard address, consisting of all zeros, can be written as
+.IR :: .
+.IP \[bu]
+An alternate format is useful for expressing IPv4-mapped IPv6 addresses.
+This form is written as
+.IR x:x:x:x:x:x:d.d.d.d ,
+where the six leading
+.IR x s
+are hexadecimal values that define the six most-significant
+16-bit pieces of the address (i.e., 96 bits), and the
+.IR d s
+express a value in dotted-decimal notation that
+defines the least significant 32 bits of the address.
+An example of such an address is
+.IR ::FFFF:204.152.189.116 .
+.RE
+.IP
+See RFC 2373 for further details on the representation of IPv6 addresses.
+.SH RETURN VALUE
+.BR inet_pton ()
+returns 1 on success (network address was successfully converted).
+0 is returned if
+.I src
+does not contain a character string representing a valid network
+address in the specified address family.
+If
+.I af
+does not contain a valid address family, \-1 is returned and
+.I errno
+is set to
+.BR EAFNOSUPPORT .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR inet_pton ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+Unlike
+.BR inet_aton (3)
+and
+.BR inet_addr (3),
+.BR inet_pton ()
+supports IPv6 addresses.
+On the other hand,
+.BR inet_pton ()
+accepts only IPv4 addresses in dotted-decimal notation, whereas
+.BR inet_aton (3)
+and
+.BR inet_addr (3)
+allow the more general numbers-and-dots notation (hexadecimal
+and octal number formats, and formats that don't require all
+four bytes to be explicitly written).
+For an interface that handles both IPv6 addresses, and IPv4
+addresses in numbers-and-dots notation, see
+.BR getaddrinfo (3).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH BUGS
+.B AF_INET6
+does not recognize IPv4 addresses.
+An explicit IPv4-mapped IPv6 address must be supplied in
+.I src
+instead.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR inet_pton ()
+and
+.BR inet_ntop (3).
+Here are some example runs:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out i6 0:0:0:0:0:0:0:0"
+::
+.RB "$" " ./a.out i6 1:0:0:0:0:0:0:8"
+1::8
+.RB "$" " ./a.out i6 0:0:0:0:0:FFFF:204.152.189.116"
+::ffff:204.152.189.116
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (inet_pton.c)
+.EX
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    unsigned char buf[sizeof(struct in6_addr)];
+    int domain, s;
+    char str[INET6_ADDRSTRLEN];
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s {i4|i6|<num>} string\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    domain = (strcmp(argv[1], "i4") == 0) ? AF_INET :
+             (strcmp(argv[1], "i6") == 0) ? AF_INET6 : atoi(argv[1]);
+\&
+    s = inet_pton(domain, argv[2], buf);
+    if (s <= 0) {
+        if (s == 0)
+            fprintf(stderr, "Not in presentation format");
+        else
+            perror("inet_pton");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (inet_ntop(domain, buf, str, INET6_ADDRSTRLEN) == NULL) {
+        perror("inet_ntop");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("%s\en", str);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getaddrinfo (3),
+.BR inet (3),
+.BR inet_ntop (3)
diff --git a/man/man3/initgroups.3 b/man/man3/initgroups.3
new file mode 100644
index 000000000..46e1b8501
--- /dev/null
+++ b/man/man3/initgroups.3
@@ -0,0 +1,98 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 2004-10-10 by aeb
+.\"
+.TH initgroups 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+initgroups \- initialize the supplementary group access list
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <grp.h>
+.P
+.BI "int initgroups(const char *" user ", gid_t " group );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR initgroups ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR initgroups ()
+function initializes the group access list by
+reading the group database
+.I /etc/group
+and using all groups of
+which
+.I user
+is a member.
+The additional group
+.I group
+is
+also added to the list.
+.P
+The
+.I user
+argument must be non-NULL.
+.SH RETURN VALUE
+The
+.BR initgroups ()
+function returns 0 on success.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient memory to allocate group information structure.
+.TP
+.B EPERM
+The calling process has insufficient privilege.
+See the underlying system call
+.BR setgroups (2).
+.SH FILES
+.TP
+.I /etc/group
+group database file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR initgroups ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR getgroups (2),
+.BR setgroups (2),
+.BR credentials (7)
diff --git a/man/man3/initstate.3 b/man/man3/initstate.3
new file mode 100644
index 000000000..6e34104e2
--- /dev/null
+++ b/man/man3/initstate.3
@@ -0,0 +1 @@
+.so man3/random.3
diff --git a/man/man3/initstate_r.3 b/man/man3/initstate_r.3
new file mode 100644
index 000000000..b01937f4d
--- /dev/null
+++ b/man/man3/initstate_r.3
@@ -0,0 +1 @@
+.so man3/random_r.3
diff --git a/man/man3/innetgr.3 b/man/man3/innetgr.3
new file mode 100644
index 000000000..34268f941
--- /dev/null
+++ b/man/man3/innetgr.3
@@ -0,0 +1 @@
+.so man3/setnetgrent.3
diff --git a/man/man3/insque.3 b/man/man3/insque.3
new file mode 100644
index 000000000..fedbbc214
--- /dev/null
+++ b/man/man3/insque.3
@@ -0,0 +1,248 @@
+'\" t
+.\" peter memishian -- meem@gnu.ai.mit.edu
+.\" $Id: insque.3,v 1.2 1996/10/30 21:03:39 meem Exp meem $
+.\" and Copyright (c) 2010, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"   Linux libc source code (5.4.7)
+.\"   Solaris 2.x, OSF/1, and HP-UX manpages
+.\"   Curry's "UNIX Systems Programming for SVR4" (O'Reilly & Associates 1996)
+.\"
+.\" Changed to POSIX, 2003-08-11, aeb+wh
+.\" mtk, 2010-09-09: Noted glibc 2.4 bug, added info on circular
+.\"	lists, added example program
+.\"
+.TH insque 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+insque, remque \- insert/remove an item from a queue
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <search.h>
+.P
+.BI "void insque(void *" elem ", void *" prev );
+.BI "void remque(void *" elem );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR insque (),
+.BR remque ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR insque ()
+and
+.BR remque ()
+functions manipulate doubly linked lists.
+Each element in the list is a structure of
+which the first two elements are a forward and a
+backward pointer.
+The linked list may be linear (i.e., NULL forward pointer at
+the end of the list and NULL backward pointer at the start of the list)
+or circular.
+.P
+The
+.BR insque ()
+function inserts the element pointed to by \fIelem\fP
+immediately after the element pointed to by \fIprev\fP.
+.P
+If the list is linear, then the call
+.I "insque(elem, NULL)"
+can be used to insert the initial list element,
+and the call sets the forward and backward pointers of
+.I elem
+to NULL.
+.P
+If the list is circular,
+the caller should ensure that the forward and backward pointers of the
+first element are initialized to point to that element,
+and the
+.I prev
+argument of the
+.BR insque ()
+call should also point to the element.
+.P
+The
+.BR remque ()
+function removes the element pointed to by \fIelem\fP from the
+doubly linked list.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR insque (),
+.BR remque ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On ancient systems,
+.\" e.g., SunOS, Linux libc4 and libc5
+the arguments of these functions were of type \fIstruct qelem *\fP,
+defined as:
+.P
+.in +4n
+.EX
+struct qelem {
+    struct qelem *q_forw;
+    struct qelem *q_back;
+    char          q_data[1];
+};
+.EE
+.in
+.P
+This is still what you will get if
+.B _GNU_SOURCE
+is defined before
+including \fI<search.h>\fP.
+.P
+The location of the prototypes for these functions differs among several
+versions of UNIX.
+The above is the POSIX version.
+Some systems place them in \fI<string.h>\fP.
+.\" Linux libc4 and libc 5 placed them
+.\" in \fI<stdlib.h>\fP.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH BUGS
+In glibc 2.4 and earlier, it was not possible to specify
+.I prev
+as NULL.
+Consequently, to build a linear list, the caller had to build a list
+using an initial call that contained the first two elements of the list,
+with the forward and backward pointers in each element suitably initialized.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR insque ().
+Here is an example run of the program:
+.P
+.in +4n
+.EX
+.RB "$ " "./a.out \-c a b c"
+Traversing completed list:
+    a
+    b
+    c
+That was a circular list
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (insque.c)
+.EX
+#include <search.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+struct element {
+    struct element *forward;
+    struct element *backward;
+    char *name;
+};
+\&
+static struct element *
+new_element(void)
+{
+    struct element *e;
+\&
+    e = malloc(sizeof(*e));
+    if (e == NULL) {
+        fprintf(stderr, "malloc() failed\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    return e;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    struct element *first, *elem, *prev;
+    int circular, opt, errfnd;
+\&
+    /* The "\-c" command\-line option can be used to specify that the
+       list is circular. */
+\&
+    errfnd = 0;
+    circular = 0;
+    while ((opt = getopt(argc, argv, "c")) != \-1) {
+        switch (opt) {
+        case \[aq]c\[aq]:
+            circular = 1;
+            break;
+        default:
+            errfnd = 1;
+            break;
+        }
+    }
+\&
+    if (errfnd || optind >= argc) {
+        fprintf(stderr,  "Usage: %s [\-c] string...\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Create first element and place it in the linked list. */
+\&
+    elem = new_element();
+    first = elem;
+\&
+    elem\->name = argv[optind];
+\&
+    if (circular) {
+        elem\->forward = elem;
+        elem\->backward = elem;
+        insque(elem, elem);
+    } else {
+        insque(elem, NULL);
+    }
+\&
+    /* Add remaining command\-line arguments as list elements. */
+\&
+    while (++optind < argc) {
+        prev = elem;
+\&
+        elem = new_element();
+        elem\->name = argv[optind];
+        insque(elem, prev);
+    }
+\&
+    /* Traverse the list from the start, printing element names. */
+\&
+    printf("Traversing completed list:\en");
+    elem = first;
+    do {
+        printf("    %s\en", elem\->name);
+        elem = elem\->forward;
+    } while (elem != NULL && elem != first);
+\&
+    if (elem == first)
+        printf("That was a circular list\en");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR queue (7)
diff --git a/man/man3/intro.3 b/man/man3/intro.3
new file mode 100644
index 000000000..1f75df9a1
--- /dev/null
+++ b/man/man3/intro.3
@@ -0,0 +1,135 @@
+.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2007-10-23 mtk, Nearly a complete rewrite of the earlier page.
+.TH intro 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to library functions
+.SH DESCRIPTION
+Section 3 of the manual describes all library functions
+excluding the library functions
+(system call wrappers)
+described in Section 2,
+which implement system calls.
+.P
+Many of the functions described in the section are part of the
+Standard C Library
+.RI ( libc ).
+Some functions are part of other libraries
+(e.g.,
+the math library,
+.IR libm ,
+or the real-time library,
+.IR librt )
+in which case the manual page will indicate
+the linker option needed to link against the required library
+(e.g.,
+.I \-lm
+and
+.IR \-lrt ,
+respectively,
+for the aforementioned libraries).
+.P
+In some cases,
+the programmer must define a feature test macro in order to obtain
+the declaration of a function from the header file specified
+in the man page SYNOPSIS section.
+(Where required,
+these
+.I feature test macros
+must be defined before including
+.I any
+header files.)
+In such cases,
+the required macro is described in the man page.
+For further information on feature test macros,
+see
+.BR feature_test_macros (7).
+.\"
+.\" There
+.\" are various function groups which can be identified by a letter which
+.\" is appended to the chapter number:
+.\" .IP (3C)
+.\" These functions,
+.\" the functions from chapter 2 and from chapter 3S are
+.\" contained in the C standard library libc,
+.\" which will be used by
+.\" .BR cc (1)
+.\" by default.
+.\" .IP (3S)
+.\" These functions are parts of the
+.\" .BR stdio (3)
+.\" library.  They are contained in the standard C library libc.
+.\" .IP (3M)
+.\" These functions are contained in the arithmetic library libm.  They are
+.\" used by the
+.\" .BR f77 (1)
+.\" FORTRAN compiler by default,
+.\" but not by the
+.\" .BR cc (1)
+.\" C compiler,
+.\" which needs the option \fI\-lm\fP.
+.\" .IP (3F)
+.\" These functions are part of the FORTRAN library libF77.  There are no
+.\" special compiler flags needed to use these functions.
+.\" .IP (3X)
+.\" Various special libraries.  The manual pages documenting their functions
+.\" specify the library names.
+.SS Subsections
+Section 3 of this manual is organized into subsections
+that reflect the complex structure of the standard C library
+and its many implementations:
+.IP \[bu] 3
+3const
+.IP \[bu]
+3head
+.IP \[bu]
+3type
+.P
+This difficult history frequently makes it a poor example to follow
+in design,
+implementation,
+and presentation.
+.P
+Ideally,
+a library for the C language
+is designed such that each header file
+presents the interface to a coherent software module.
+It provides a small number of function declarations
+and exposes only data types and constants that
+are required for use of those functions.
+Together,
+these are termed an API or
+.IR "application program interface" .
+Types and constants to be shared among multiple APIs
+should be placed in header files that declare no functions.
+This organization permits a C library module
+to be documented concisely with one header file per manual page.
+Such an approach
+improves the readability and accessibility of library documentation,
+and thereby the usability of the software.
+.SH STANDARDS
+Certain terms and abbreviations are used to indicate UNIX variants
+and standards to which calls in this section conform.
+See
+.BR standards (7).
+.SH NOTES
+.SS Authors and copyright conditions
+Look at the header of the manual page source
+for the author(s) and copyright conditions.
+Note that these can be different from page to page!
+.SH SEE ALSO
+.BR intro (2),
+.BR errno (3),
+.BR capabilities (7),
+.BR credentials (7),
+.BR environ (7),
+.BR feature_test_macros (7),
+.BR libc (7),
+.BR math_error (7),
+.BR path_resolution (7),
+.BR pthreads (7),
+.BR signal (7),
+.BR standards (7),
+.BR system_data_types (7)
diff --git a/man/man3/iruserok.3 b/man/man3/iruserok.3
new file mode 100644
index 000000000..b58efefab
--- /dev/null
+++ b/man/man3/iruserok.3
@@ -0,0 +1 @@
+.so man3/rcmd.3
diff --git a/man/man3/iruserok_af.3 b/man/man3/iruserok_af.3
new file mode 100644
index 000000000..b58efefab
--- /dev/null
+++ b/man/man3/iruserok_af.3
@@ -0,0 +1 @@
+.so man3/rcmd.3
diff --git a/man/man3/isalnum.3 b/man/man3/isalnum.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isalnum.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isalnum_l.3 b/man/man3/isalnum_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isalnum_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isalpha.3 b/man/man3/isalpha.3
new file mode 100644
index 000000000..05d373780
--- /dev/null
+++ b/man/man3/isalpha.3
@@ -0,0 +1,405 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 19:10:00 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Aug 21 17:51:50 1994 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sat Sep  2 21:52:01 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" Modified Mon May 27 22:55:26 1996 by Martin Schulze (joey@linux.de)
+.\"
+.TH isalpha 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower,
+isprint, ispunct, isspace, isupper, isxdigit,
+isalnum_l, isalpha_l, isascii_l, isblank_l, iscntrl_l,
+isdigit_l, isgraph_l, islower_l,
+isprint_l, ispunct_l, isspace_l, isupper_l, isxdigit_l
+\- character classification functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <ctype.h>
+.P
+.BI "int isalnum(int " c );
+.BI "int isalpha(int " c );
+.BI "int iscntrl(int " c );
+.BI "int isdigit(int " c );
+.BI "int isgraph(int " c );
+.BI "int islower(int " c );
+.BI "int isprint(int " c );
+.BI "int ispunct(int " c );
+.BI "int isspace(int " c );
+.BI "int isupper(int " c );
+.BI "int isxdigit(int " c );
+.P
+.BI "int isascii(int " c );
+.BI "int isblank(int " c );
+.P
+.BI "int isalnum_l(int " c ", locale_t " locale );
+.BI "int isalpha_l(int " c ", locale_t " locale );
+.BI "int isblank_l(int " c ", locale_t " locale );
+.BI "int iscntrl_l(int " c ", locale_t " locale );
+.BI "int isdigit_l(int " c ", locale_t " locale );
+.BI "int isgraph_l(int " c ", locale_t " locale );
+.BI "int islower_l(int " c ", locale_t " locale );
+.BI "int isprint_l(int " c ", locale_t " locale );
+.BI "int ispunct_l(int " c ", locale_t " locale );
+.BI "int isspace_l(int " c ", locale_t " locale );
+.BI "int isupper_l(int " c ", locale_t " locale );
+.BI "int isxdigit_l(int " c ", locale_t " locale );
+.P
+.BI "int isascii_l(int " c ", locale_t " locale );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.ad l
+.P
+.BR isascii ():
+.nf
+    _XOPEN_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE
+.fi
+.P
+.BR isblank ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.P
+.BR \%salnum_l (),
+.BR \%salpha_l (),
+.BR \%sblank_l (),
+.BR \%scntrl_l (),
+.BR \%sdigit_l (),
+.BR \%sgraph_l (),
+.BR \%slower_l (),
+.BR \%sprint_l (),
+.BR \%spunct_l (),
+.BR \%sspace_l (),
+.BR \%supper_l (),
+.BR \%sxdigit_l ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.P
+.BR isascii_l ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700 && (_SVID_SOURCE || _BSD_SOURCE)
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.ad
+.SH DESCRIPTION
+These functions check whether
+.IR c ,
+which must have the value of an
+.I unsigned char
+or
+.BR EOF ,
+falls into a certain character class according to the specified locale.
+The functions without the
+"_l" suffix perform the check based on the current locale.
+.P
+The functions with the "_l" suffix perform the check
+based on the locale specified by the locale object
+.IR locale .
+The behavior of these functions is undefined if
+.I locale
+is the special locale object
+.B LC_GLOBAL_LOCALE
+(see
+.BR duplocale (3))
+or is not a valid locale object handle.
+.P
+The list below explains the operation of the functions without
+the "_l" suffix;
+the functions with the "_l" suffix differ only in using the locale object
+.I locale
+instead of the current locale.
+.TP
+.BR isalnum ()
+checks for an alphanumeric character; it is equivalent to
+.BI "(isalpha(" c ") || isdigit(" c "))" \fR.
+.TP
+.BR isalpha ()
+checks for an alphabetic character; in the standard \fB"C"\fP
+locale, it is equivalent to
+.BI "(isupper(" c ") || islower(" c "))" \fR.
+In some locales, there may be additional characters for which
+.BR isalpha ()
+is true\[em]letters which are neither uppercase nor lowercase.
+.TP
+.BR isascii ()
+checks whether \fIc\fP is a 7-bit
+.I unsigned char
+value that fits into
+the ASCII character set.
+.TP
+.BR isblank ()
+checks for a blank character; that is, a space or a tab.
+.TP
+.BR iscntrl ()
+checks for a control character.
+.TP
+.BR isdigit ()
+checks for a digit (0 through 9).
+.TP
+.BR isgraph ()
+checks for any printable character except space.
+.TP
+.BR islower ()
+checks for a lowercase character.
+.TP
+.BR isprint ()
+checks for any printable character including space.
+.TP
+.BR ispunct ()
+checks for any printable character which is not a space or an
+alphanumeric character.
+.TP
+.BR isspace ()
+checks for white-space characters.
+In the
+.B \[dq]C\[dq]
+and
+.B \[dq]POSIX\[dq]
+locales, these are: space, form-feed
+.RB ( \[aq]\ef\[aq] ),
+newline
+.RB ( \[aq]\en\[aq] ),
+carriage return
+.RB ( \[aq]\er\[aq] ),
+horizontal tab
+.RB ( \[aq]\et\[aq] ),
+and vertical tab
+.RB ( \[aq]\ev\[aq] ).
+.TP
+.BR isupper ()
+checks for an uppercase letter.
+.TP
+.BR isxdigit ()
+checks for hexadecimal digits, that is, one of
+.br
+.BR "0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F" .
+.SH RETURN VALUE
+The values returned are nonzero if the character
+.I c
+falls into the tested class, and zero if not.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR isalnum (),
+.BR isalpha (),
+.BR isascii (),
+.BR isblank (),
+.BR iscntrl (),
+.BR isdigit (),
+.BR isgraph (),
+.BR islower (),
+.BR isprint (),
+.BR ispunct (),
+.BR isspace (),
+.BR isupper (),
+.BR isxdigit ()
+T}	Thread safety	MT-Safe
+.TE
+.\" FIXME: need a thread-safety statement about the *_l functions
+.SH STANDARDS
+.TP
+.BR isalnum ()
+.TQ
+.BR isalpha ()
+.TQ
+.BR iscntrl ()
+.TQ
+.BR isdigit ()
+.TQ
+.BR isgraph ()
+.TQ
+.BR islower ()
+.TQ
+.BR isprint ()
+.TQ
+.BR ispunct ()
+.TQ
+.BR isspace ()
+.TQ
+.BR isupper ()
+.TQ
+.BR isxdigit ()
+.TQ
+.BR isblank ()
+C11, POSIX.1-2008.
+.TP
+.BR isascii ()
+.TQ
+.BR isalnum_l ()
+.TQ
+.BR isalpha_l ()
+.TQ
+.BR isblank_l ()
+.TQ
+.BR iscntrl_l ()
+.TQ
+.BR isdigit_l ()
+.TQ
+.BR isgraph_l ()
+.TQ
+.BR islower_l ()
+.TQ
+.BR isprint_l ()
+.TQ
+.BR ispunct_l ()
+.TQ
+.BR isspace_l ()
+.TQ
+.BR isupper_l ()
+.TQ
+.BR isxdigit_l ()
+POSIX.1-2008.
+.TP
+.BR isascii_l ()
+GNU.
+.SH HISTORY
+.TP
+.BR isalnum ()
+.TQ
+.BR isalpha ()
+.TQ
+.BR iscntrl ()
+.TQ
+.BR isdigit ()
+.TQ
+.BR isgraph ()
+.TQ
+.BR islower ()
+.TQ
+.BR isprint ()
+.TQ
+.BR ispunct ()
+.TQ
+.BR isspace ()
+.TQ
+.BR isupper ()
+.TQ
+.BR isxdigit ()
+C89, POSIX.1-2001.
+.TP
+.BR isblank ()
+C99, POSIX.1-2001.
+.TP
+.BR isascii ()
+POSIX.1-2001 (XSI).
+.IP
+POSIX.1-2008 marks it as obsolete,
+noting that it cannot be used portably in a localized application.
+.TP
+.BR isalnum_l ()
+.TQ
+.BR isalpha_l ()
+.TQ
+.BR isblank_l ()
+.TQ
+.BR iscntrl_l ()
+.TQ
+.BR isdigit_l ()
+.TQ
+.BR isgraph_l ()
+.TQ
+.BR islower_l ()
+.TQ
+.BR isprint_l ()
+.TQ
+.BR ispunct_l ()
+.TQ
+.BR isspace_l ()
+.TQ
+.BR isupper_l ()
+.TQ
+.BR isxdigit_l ()
+glibc 2.3.
+POSIX.1-2008.
+.TP
+.BR isascii_l ()
+glibc 2.3.
+.SH CAVEATS
+The standards require that the argument
+.I c
+for these functions is either
+.B EOF
+or a value that is representable in the type
+.IR "unsigned char" ;
+otherwise,
+the behavior is undefined.
+If the argument
+.I c
+is of type
+.IR char ,
+it must be cast to
+.IR "unsigned char" ,
+as in the following example:
+.P
+.in +4n
+.EX
+char c;
+\&...
+res = toupper((unsigned char) c);
+.EE
+.in
+.P
+This is necessary because
+.I char
+may be the equivalent of
+.IR "signed char" ,
+in which case a byte where the top bit is set would be sign extended when
+converting to
+.IR int ,
+yielding a value that is outside the range of
+.IR "unsigned char" .
+.P
+The details of what characters belong to which class depend on the
+locale.
+For example,
+.BR isupper ()
+will not recognize an A-umlaut (\(:A) as an uppercase letter in the default
+.B "C"
+locale.
+.SH SEE ALSO
+.BR iswalnum (3),
+.BR iswalpha (3),
+.BR iswblank (3),
+.BR iswcntrl (3),
+.BR iswdigit (3),
+.BR iswgraph (3),
+.BR iswlower (3),
+.BR iswprint (3),
+.BR iswpunct (3),
+.BR iswspace (3),
+.BR iswupper (3),
+.BR iswxdigit (3),
+.BR newlocale (3),
+.BR setlocale (3),
+.BR toascii (3),
+.BR tolower (3),
+.BR toupper (3),
+.BR uselocale (3),
+.BR ascii (7),
+.BR locale (7)
diff --git a/man/man3/isalpha_l.3 b/man/man3/isalpha_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isalpha_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isascii.3 b/man/man3/isascii.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isascii.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isascii_l.3 b/man/man3/isascii_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isascii_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isatty.3 b/man/man3/isatty.3
new file mode 100644
index 000000000..84342ff40
--- /dev/null
+++ b/man/man3/isatty.3
@@ -0,0 +1,68 @@
+'\" t
+.\" Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH isatty 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+isatty \- test whether a file descriptor refers to a terminal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int isatty(int " fd );
+.fi
+.SH DESCRIPTION
+The
+.BR isatty ()
+function tests whether
+.I fd
+is an open file descriptor referring to a terminal.
+.SH RETURN VALUE
+.BR isatty ()
+returns 1 if
+.I fd
+is an open file descriptor referring to a terminal;
+otherwise 0 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B ENOTTY
+.I fd
+refers to a file other than a terminal.
+On some older kernels, some types of files
+.\" e.g., FIFOs and pipes on 2.6.32
+resulted in the error
+.B EINVAL
+in this case (which is a violation of POSIX, which specifies the error
+.BR ENOTTY ).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR isatty ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR fstat (2),
+.BR ttyname (3)
diff --git a/man/man3/isblank.3 b/man/man3/isblank.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isblank.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isblank_l.3 b/man/man3/isblank_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isblank_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/iscntrl.3 b/man/man3/iscntrl.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/iscntrl.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/iscntrl_l.3 b/man/man3/iscntrl_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/iscntrl_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isdigit.3 b/man/man3/isdigit.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isdigit.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isdigit_l.3 b/man/man3/isdigit_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isdigit_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isfdtype.3 b/man/man3/isfdtype.3
new file mode 100644
index 000000000..5ccfeb783
--- /dev/null
+++ b/man/man3/isfdtype.3
@@ -0,0 +1,77 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH isfdtype 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+isfdtype \- test file type of a file descriptor
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/stat.h>
+.B #include <sys/socket.h>
+.P
+.BI "int isfdtype(int " fd ", int " fdtype );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR isfdtype ():
+.nf
+    Since glibc 2.20:
+        _DEFAULT_SOURCE
+    Before glibc 2.20:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR isfdtype ()
+function tests whether the file descriptor
+.I fd
+refers to a file of type
+.IR fdtype .
+The
+.I fdtype
+argument specifies one of the
+.B S_IF*
+constants defined in
+.I <sys/stat.h>
+and documented in
+.BR stat (2)
+(e.g.,
+.BR S_IFREG ).
+.SH RETURN VALUE
+The
+.BR isfdtype ()
+function returns 1 if the file descriptor
+.I fd
+is of type
+.I fdtype
+and 0 if it is not.
+On failure, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The
+.BR isfdtype ()
+function can fail with any of the same errors as
+.BR fstat (2).
+.SH VERSIONS
+Portable applications should use
+.BR fstat (2)
+instead.
+.SH STANDARDS
+None.
+.SH HISTORY
+It appeared in the draft POSIX.1g standard.
+It is present on OpenBSD and Tru64 UNIX
+(where the required header file in both cases is just
+.IR <sys/stat.h> ,
+as shown in the POSIX.1g draft).
+.SH SEE ALSO
+.BR fstat (2)
diff --git a/man/man3/isfinite.3 b/man/man3/isfinite.3
new file mode 100644
index 000000000..17676c2c7
--- /dev/null
+++ b/man/man3/isfinite.3
@@ -0,0 +1 @@
+.so man3/fpclassify.3
diff --git a/man/man3/isgraph.3 b/man/man3/isgraph.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isgraph.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isgraph_l.3 b/man/man3/isgraph_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isgraph_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isgreater.3 b/man/man3/isgreater.3
new file mode 100644
index 000000000..a2e52d18c
--- /dev/null
+++ b/man/man3/isgreater.3
@@ -0,0 +1,144 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" 2002-07-27 Walter Harms
+.\" this was done with the help of the glibc manual
+.\"
+.TH isgreater 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+isgreater, isgreaterequal, isless, islessequal, islessgreater,
+isunordered \- floating-point relational tests without exception for NaN
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "int isgreater(" x ", " y );
+.BI "int isgreaterequal(" x ", " y );
+.BI "int isless(" x ", " y );
+.BI "int islessequal(" x ", " y );
+.BI "int islessgreater(" x ", " y );
+.BI "int isunordered(" x ", " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.nf
+    All functions described here:
+        _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The normal relational operations (like
+.BR < ,
+"less than")
+fail if one of the operands is NaN.
+This will cause an exception.
+To avoid this, C99 defines the macros listed below.
+.P
+These macros are guaranteed to evaluate their arguments only once.
+The arguments must be of real floating-point type (note: do not pass
+integer values as arguments to these macros, since the arguments will
+.I not
+be promoted to real-floating types).
+.TP
+.BR isgreater ()
+determines \fI(x)\ >\ (y)\fP without an exception
+if
+.I x
+or
+.I y
+is NaN.
+.TP
+.BR isgreaterequal ()
+determines \fI(x)\ >=\ (y)\fP without an exception
+if
+.I x
+or
+.I y
+is NaN.
+.TP
+.BR isless ()
+determines \fI(x)\ <\ (y)\fP without an exception
+if
+.I x
+or
+.I y
+is NaN.
+.TP
+.BR islessequal ()
+determines \fI(x)\ <=\ (y)\fP without an exception
+if
+.I x
+or
+.I y
+is NaN.
+.TP
+.BR islessgreater ()
+determines \fI(x)\ < (y) || (x) >\ (y)\fP
+without an exception if
+.I x
+or
+.I y
+is NaN.
+This macro is not equivalent to \fIx\ !=\ y\fP because that expression is
+true if
+.I x
+or
+.I y
+is NaN.
+.TP
+.BR isunordered ()
+determines whether its arguments are unordered, that is, whether
+at least one of the arguments is a NaN.
+.SH RETURN VALUE
+The macros other than
+.BR isunordered ()
+return the result of the relational comparison;
+these macros return 0 if either argument is a NaN.
+.P
+.BR isunordered ()
+returns 1 if
+.I x
+or
+.I y
+is NaN and 0 otherwise.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR isgreater (),
+.BR isgreaterequal (),
+.BR isless (),
+.BR islessequal (),
+.BR islessgreater (),
+.BR isunordered ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Not all hardware supports these functions,
+and where hardware support isn't provided, they will be emulated by macros.
+This will result in a performance penalty.
+Don't use these functions if NaN is of no concern for you.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR fpclassify (3),
+.BR isnan (3)
diff --git a/man/man3/isgreaterequal.3 b/man/man3/isgreaterequal.3
new file mode 100644
index 000000000..24410b964
--- /dev/null
+++ b/man/man3/isgreaterequal.3
@@ -0,0 +1 @@
+.so man3/isgreater.3
diff --git a/man/man3/isinf.3 b/man/man3/isinf.3
new file mode 100644
index 000000000..17676c2c7
--- /dev/null
+++ b/man/man3/isinf.3
@@ -0,0 +1 @@
+.so man3/fpclassify.3
diff --git a/man/man3/isinff.3 b/man/man3/isinff.3
new file mode 100644
index 000000000..19f709b1c
--- /dev/null
+++ b/man/man3/isinff.3
@@ -0,0 +1 @@
+.so man3/finite.3
diff --git a/man/man3/isinfl.3 b/man/man3/isinfl.3
new file mode 100644
index 000000000..19f709b1c
--- /dev/null
+++ b/man/man3/isinfl.3
@@ -0,0 +1 @@
+.so man3/finite.3
diff --git a/man/man3/isless.3 b/man/man3/isless.3
new file mode 100644
index 000000000..24410b964
--- /dev/null
+++ b/man/man3/isless.3
@@ -0,0 +1 @@
+.so man3/isgreater.3
diff --git a/man/man3/islessequal.3 b/man/man3/islessequal.3
new file mode 100644
index 000000000..24410b964
--- /dev/null
+++ b/man/man3/islessequal.3
@@ -0,0 +1 @@
+.so man3/isgreater.3
diff --git a/man/man3/islessgreater.3 b/man/man3/islessgreater.3
new file mode 100644
index 000000000..24410b964
--- /dev/null
+++ b/man/man3/islessgreater.3
@@ -0,0 +1 @@
+.so man3/isgreater.3
diff --git a/man/man3/islower.3 b/man/man3/islower.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/islower.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/islower_l.3 b/man/man3/islower_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/islower_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isnan.3 b/man/man3/isnan.3
new file mode 100644
index 000000000..17676c2c7
--- /dev/null
+++ b/man/man3/isnan.3
@@ -0,0 +1 @@
+.so man3/fpclassify.3
diff --git a/man/man3/isnanf.3 b/man/man3/isnanf.3
new file mode 100644
index 000000000..19f709b1c
--- /dev/null
+++ b/man/man3/isnanf.3
@@ -0,0 +1 @@
+.so man3/finite.3
diff --git a/man/man3/isnanl.3 b/man/man3/isnanl.3
new file mode 100644
index 000000000..19f709b1c
--- /dev/null
+++ b/man/man3/isnanl.3
@@ -0,0 +1 @@
+.so man3/finite.3
diff --git a/man/man3/isnormal.3 b/man/man3/isnormal.3
new file mode 100644
index 000000000..17676c2c7
--- /dev/null
+++ b/man/man3/isnormal.3
@@ -0,0 +1 @@
+.so man3/fpclassify.3
diff --git a/man/man3/isprint.3 b/man/man3/isprint.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isprint.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isprint_l.3 b/man/man3/isprint_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isprint_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/ispunct.3 b/man/man3/ispunct.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/ispunct.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/ispunct_l.3 b/man/man3/ispunct_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/ispunct_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isspace.3 b/man/man3/isspace.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isspace.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isspace_l.3 b/man/man3/isspace_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isspace_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isunordered.3 b/man/man3/isunordered.3
new file mode 100644
index 000000000..24410b964
--- /dev/null
+++ b/man/man3/isunordered.3
@@ -0,0 +1 @@
+.so man3/isgreater.3
diff --git a/man/man3/isupper.3 b/man/man3/isupper.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isupper.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isupper_l.3 b/man/man3/isupper_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isupper_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/iswalnum.3 b/man/man3/iswalnum.3
new file mode 100644
index 000000000..e0f73c801
--- /dev/null
+++ b/man/man3/iswalnum.3
@@ -0,0 +1,95 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswalnum 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswalnum \- test for alphanumeric wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswalnum(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswalnum ()
+function is the wide-character equivalent of the
+.BR isalnum (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "alnum".
+.P
+The wide-character class "alnum" is a subclass of the wide-character class
+"graph", and therefore also a subclass of the wide-character class "print".
+.P
+Being a subclass of the wide-character class "print",
+the wide-character class
+"alnum" is disjoint from the wide-character class "cntrl".
+.P
+Being a subclass of the wide-character class "graph",
+the wide-character class "alnum" is disjoint from
+the wide-character class "space" and its subclass "blank".
+.P
+The wide-character class "alnum" is disjoint from the wide-character class
+"punct".
+.P
+The wide-character class "alnum" is the union of the wide-character classes
+"alpha" and "digit".
+As such, it also contains the wide-character class
+"xdigit".
+.P
+The wide-character class "alnum"
+always contains at least the letters
+\[aq]A\[aq] to \[aq]Z\[aq],
+\[aq]a\[aq] to \[aq]z\[aq],
+and the digits \[aq]0\[aq] to \[aq]9\[aq].
+.SH RETURN VALUE
+The
+.BR iswalnum ()
+function returns nonzero
+if
+.I wc
+is a wide character
+belonging to the wide-character class "alnum".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswalnum ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswalnum ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR isalnum (3),
+.BR iswctype (3)
diff --git a/man/man3/iswalpha.3 b/man/man3/iswalpha.3
new file mode 100644
index 000000000..0fa88e9bd
--- /dev/null
+++ b/man/man3/iswalpha.3
@@ -0,0 +1,96 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswalpha 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswalpha \- test for alphabetic wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswalpha(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswalpha ()
+function is the wide-character equivalent of the
+.BR isalpha (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "alpha".
+.P
+The wide-character class "alpha" is a subclass of the
+wide-character class "alnum",
+and therefore also a subclass of the wide-character class "graph" and
+of the wide-character class "print".
+.P
+Being a subclass of the wide-character class "print",
+the wide-character class
+"alpha" is disjoint from the wide-character class "cntrl".
+.P
+Being a subclass of the wide-character class "graph",
+the wide-character class "alpha" is disjoint from
+the wide-character class "space" and its subclass "blank".
+.P
+Being a subclass of the wide-character class "alnum",
+the wide-character class "alpha" is disjoint from the
+wide-character class "punct".
+.P
+The wide-character class "alpha" is disjoint from the wide-character class
+"digit".
+.P
+The wide-character class "alpha" contains the wide-character classes "upper"
+and "lower".
+.P
+The wide-character class "alpha" always contains at least the
+letters \[aq]A\[aq] to \[aq]Z\[aq] and \[aq]a\[aq] to \[aq]z\[aq].
+.SH RETURN VALUE
+The
+.BR iswalpha ()
+function returns nonzero
+if
+.I wc
+is a wide character
+belonging to the wide-character class "alpha".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswalpha ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswalpha ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR isalpha (3),
+.BR iswctype (3)
diff --git a/man/man3/iswblank.3 b/man/man3/iswblank.3
new file mode 100644
index 000000000..79c89ba59
--- /dev/null
+++ b/man/man3/iswblank.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswblank 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswblank \- test for whitespace wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswblank(wint_t " wc );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR iswblank ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR iswblank ()
+function is the wide-character equivalent of the
+.BR isblank (3)
+function.
+It tests whether \fIwc\fP is a wide character
+belonging to the wide-character class "blank".
+.P
+The wide-character class "blank" is a subclass of the wide-character class
+"space".
+.P
+Being a subclass of the wide-character class "space",
+the wide-character class "blank" is disjoint from the
+wide-character class "graph" and therefore also disjoint
+from its subclasses "alnum", "alpha", "upper", "lower", "digit",
+"xdigit", "punct".
+.P
+The wide-character class "blank" always contains
+at least the space character
+and the control character \[aq]\et\[aq].
+.SH RETURN VALUE
+The
+.BR iswblank ()
+function returns nonzero
+if \fIwc\fP is a wide character
+belonging to the wide-character class "blank".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswblank ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The behavior of
+.BR iswblank ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR isblank (3),
+.BR iswctype (3)
diff --git a/man/man3/iswcntrl.3 b/man/man3/iswcntrl.3
new file mode 100644
index 000000000..3478088ca
--- /dev/null
+++ b/man/man3/iswcntrl.3
@@ -0,0 +1,80 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswcntrl 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswcntrl \- test for control wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswcntrl(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswcntrl ()
+function is the wide-character equivalent of the
+.BR iscntrl (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "cntrl".
+.P
+The wide-character class "cntrl" is disjoint from the wide-character class
+"print" and therefore also disjoint from its subclasses "graph", "alpha",
+"upper", "lower", "digit", "xdigit", "punct".
+.P
+For an unsigned char
+.IR c ,
+.I iscntrl(c)
+implies
+.IR iswcntrl(btowc(c)) ,
+but not vice versa.
+.SH RETURN VALUE
+The
+.BR iswcntrl ()
+function returns nonzero if
+.I wc
+is a
+wide character belonging to the wide-character class "cntrl".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswcntrl ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswcntrl ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR iscntrl (3),
+.BR iswctype (3)
diff --git a/man/man3/iswctype.3 b/man/man3/iswctype.3
new file mode 100644
index 000000000..bf457d5f3
--- /dev/null
+++ b/man/man3/iswctype.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswctype 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswctype \- wide-character classification
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswctype(wint_t " wc ", wctype_t " desc );
+.fi
+.SH DESCRIPTION
+If
+.I wc
+is a wide character having the character property designated by
+.I desc
+(or in other words: belongs to the character class designated by
+.IR desc ),
+then the
+.BR iswctype ()
+function returns nonzero.
+Otherwise, it
+returns zero.
+If
+.I wc
+is
+.BR WEOF ,
+zero is returned.
+.P
+.I desc
+must be a character property descriptor
+returned by the
+.BR wctype (3)
+function.
+.SH RETURN VALUE
+The
+.BR iswctype ()
+function returns nonzero if
+the
+.I wc
+has the designated
+property.
+Otherwise, it returns 0.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswctype ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswctype ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR iswalnum (3),
+.BR iswalpha (3),
+.BR iswblank (3),
+.BR iswcntrl (3),
+.BR iswdigit (3),
+.BR iswgraph (3),
+.BR iswlower (3),
+.BR iswprint (3),
+.BR iswpunct (3),
+.BR iswspace (3),
+.BR iswupper (3),
+.BR iswxdigit (3),
+.BR wctype (3)
diff --git a/man/man3/iswdigit.3 b/man/man3/iswdigit.3
new file mode 100644
index 000000000..60a088b87
--- /dev/null
+++ b/man/man3/iswdigit.3
@@ -0,0 +1,95 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswdigit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswdigit \- test for decimal digit wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswdigit(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswdigit ()
+function is the wide-character equivalent of the
+.BR isdigit (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "digit".
+.P
+The wide-character class "digit" is a subclass of the wide-character class
+"xdigit", and therefore also a subclass
+of the wide-character class "alnum", of
+the wide-character class "graph" and of the wide-character class "print".
+.P
+Being a subclass of the wide character
+class "print", the wide-character class
+"digit" is disjoint from the wide-character class "cntrl".
+.P
+Being a subclass of the wide-character class "graph",
+the wide-character class
+"digit" is disjoint from the wide-character class "space" and its subclass
+"blank".
+.P
+Being a subclass of the wide-character
+class "alnum", the wide-character class
+"digit" is disjoint from the wide-character class "punct".
+.P
+The wide-character class "digit" is
+disjoint from the wide-character class
+"alpha" and therefore also disjoint from its subclasses "lower", "upper".
+.P
+The wide-character class "digit" always
+contains exactly the digits \[aq]0\[aq] to \[aq]9\[aq].
+.SH RETURN VALUE
+The
+.BR iswdigit ()
+function returns nonzero
+if
+.I wc
+is a wide character
+belonging to the wide-character class "digit".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswdigit ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswdigit ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR isdigit (3),
+.BR iswctype (3)
diff --git a/man/man3/iswgraph.3 b/man/man3/iswgraph.3
new file mode 100644
index 000000000..9cfb3a6dc
--- /dev/null
+++ b/man/man3/iswgraph.3
@@ -0,0 +1,88 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswgraph 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswgraph \- test for graphic wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswgraph(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswgraph ()
+function is the wide-character equivalent of the
+.BR isgraph (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "graph".
+.P
+The wide-character class "graph" is a subclass of the wide-character class
+"print".
+.P
+Being a subclass of the wide-character class "print",
+the wide-character class
+"graph" is disjoint from the wide-character class "cntrl".
+.P
+The wide-character class "graph" is disjoint from the wide-character class
+"space" and therefore also disjoint from its subclass "blank".
+.\" Note: UNIX98 (susv2/xbd/locale.html) says that "graph" and "space" may
+.\" have characters in common, except U+0020. But C99 (ISO/IEC 9899:1999
+.\" section 7.25.2.1.10) says that "space" and "graph" are disjoint.
+.P
+The wide-character class "graph" contains all the wide characters from the
+wide-character class "print" except the space character.
+It therefore contains
+the wide-character classes "alnum" and "punct".
+.SH RETURN VALUE
+The
+.BR iswgraph ()
+function returns nonzero
+if
+.I wc
+is a wide character
+belonging to the wide-character class "graph".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswgraph ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswgraph ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR isgraph (3),
+.BR iswctype (3)
diff --git a/man/man3/iswlower.3 b/man/man3/iswlower.3
new file mode 100644
index 000000000..d862b4a01
--- /dev/null
+++ b/man/man3/iswlower.3
@@ -0,0 +1,106 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswlower 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswlower \- test for lowercase wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswlower(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswlower ()
+function is the wide-character equivalent of the
+.BR islower (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "lower".
+.P
+The wide-character class "lower" is a subclass of the wide-character class
+"alpha", and therefore also a subclass
+of the wide-character class "alnum", of
+the wide-character class "graph" and of the wide-character class "print".
+.P
+Being a subclass of the wide-character class "print",
+the wide-character class
+"lower" is disjoint from the wide-character class "cntrl".
+.P
+Being a subclass of the wide-character class "graph",
+the wide-character class "lower" is disjoint from the
+wide-character class "space" and its subclass "blank".
+.P
+Being a subclass of the wide-character class "alnum",
+the wide-character class
+"lower" is disjoint from the wide-character class "punct".
+.P
+Being a subclass of the wide-character class "alpha",
+the wide-character class
+"lower" is disjoint from the wide-character class "digit".
+.P
+The wide-character class "lower" contains at least
+those characters
+.I wc
+which are equal to
+.I towlower(wc)
+and different from
+.IR towupper(wc) .
+.P
+The wide-character class "lower" always contains
+at least the letters \[aq]a\[aq] to \[aq]z\[aq].
+.SH RETURN VALUE
+The
+.BR iswlower ()
+function returns nonzero
+if
+.I wc
+is a wide character
+belonging to the wide-character class "lower".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswlower ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswlower ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+This function is not very appropriate for dealing with Unicode characters,
+because Unicode knows about three cases: upper, lower, and title case.
+.SH SEE ALSO
+.BR islower (3),
+.BR iswctype (3),
+.BR towlower (3)
diff --git a/man/man3/iswprint.3 b/man/man3/iswprint.3
new file mode 100644
index 000000000..57055f6ee
--- /dev/null
+++ b/man/man3/iswprint.3
@@ -0,0 +1,74 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswprint 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswprint \- test for printing wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswprint(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswprint ()
+function is the wide-character equivalent of the
+.BR isprint (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "print".
+.P
+The wide-character class "print" is disjoint from the wide-character class
+"cntrl".
+.P
+The wide-character class "print" contains the wide-character class "graph".
+.SH RETURN VALUE
+The
+.BR iswprint ()
+function returns nonzero if
+.I wc
+is a
+wide character belonging to the wide-character class "print".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswprint ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswprint ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR isprint (3),
+.BR iswctype (3)
diff --git a/man/man3/iswpunct.3 b/man/man3/iswpunct.3
new file mode 100644
index 000000000..4f5a220a1
--- /dev/null
+++ b/man/man3/iswpunct.3
@@ -0,0 +1,90 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswpunct 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswpunct \- test for punctuation or symbolic wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswpunct(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswpunct ()
+function is the wide-character equivalent of the
+.BR ispunct (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "punct".
+.P
+The wide-character class "punct" is a subclass of the wide-character class
+"graph", and therefore also a subclass of the wide-character class "print".
+.P
+The wide-character class "punct" is disjoint from the wide-character class
+"alnum" and therefore also disjoint from its subclasses "alpha", "upper",
+"lower", "digit", "xdigit".
+.P
+Being a subclass of the wide-character class "print",
+the wide-character class
+"punct" is disjoint from the wide-character class "cntrl".
+.P
+Being a subclass of the wide-character class "graph",
+the wide-character class
+"punct" is disjoint from the wide-character class "space" and its subclass
+"blank".
+.SH RETURN VALUE
+The
+.BR iswpunct ()
+function returns nonzero
+if
+.I wc
+is a wide-character
+belonging to the wide-character class "punct".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswpunct ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswpunct ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+This function's name is a misnomer when dealing with Unicode characters,
+because the wide-character class "punct" contains both punctuation characters
+and symbol (math, currency, etc.) characters.
+.SH SEE ALSO
+.BR ispunct (3),
+.BR iswctype (3)
diff --git a/man/man3/iswspace.3 b/man/man3/iswspace.3
new file mode 100644
index 000000000..c89517b15
--- /dev/null
+++ b/man/man3/iswspace.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswspace 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswspace \- test for whitespace wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswspace(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswspace ()
+function is the wide-character equivalent of the
+.BR isspace (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "space".
+.P
+The wide-character class "space" is disjoint from the wide-character class
+"graph" and therefore also disjoint from its subclasses "alnum", "alpha",
+"upper", "lower", "digit", "xdigit", "punct".
+.\" Note: UNIX98 (susv2/xbd/locale.html) says that "space" and "graph" may
+.\" have characters in common, except U+0020. But C99 (ISO/IEC 9899:1999
+.\" section 7.25.2.1.10) says that "space" and "graph" are disjoint.
+.P
+The wide-character class "space" contains the wide-character class "blank".
+.P
+The wide-character class "space"
+always contains at least the space character
+and the control characters
+\[aq]\ef\[aq], \[aq]\en\[aq], \[aq]\er\[aq], \[aq]\et\[aq], and \[aq]\ev\[aq].
+.SH RETURN VALUE
+The
+.BR iswspace ()
+function returns nonzero if
+.I wc
+is a wide character
+belonging to the wide-character class "space".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswspace ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswspace ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR isspace (3),
+.BR iswctype (3)
diff --git a/man/man3/iswupper.3 b/man/man3/iswupper.3
new file mode 100644
index 000000000..7a64ebae1
--- /dev/null
+++ b/man/man3/iswupper.3
@@ -0,0 +1,100 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswupper 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswupper \- test for uppercase wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswupper(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswupper ()
+function is the wide-character equivalent of the
+.BR isupper (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "upper".
+.P
+The wide-character class "upper" is a subclass of the wide-character class
+"alpha", and therefore also a subclass of the wide-character class "alnum", of
+the wide-character class "graph" and of the wide-character class "print".
+.P
+Being a subclass of the wide-character class "print", the wide-character class
+"upper" is disjoint from the wide-character class "cntrl".
+.P
+Being a subclass of the wide-character class "graph", the wide-character class
+"upper" is disjoint from the wide-character class "space" and its subclass
+"blank".
+.P
+Being a subclass of the wide-character class "alnum", the wide-character class
+"upper" is disjoint from the wide-character class "punct".
+.P
+Being a subclass of the wide-character class "alpha", the wide-character class
+"upper" is disjoint from the wide-character class "digit".
+.P
+The wide-character class "upper" contains at least those characters
+.I wc
+which are equal to
+.I towupper(wc)
+and different from
+.IR towlower(wc) .
+.P
+The wide-character class "upper" always contains at least the
+letters \[aq]A\[aq] to \[aq]Z\[aq].
+.SH RETURN VALUE
+The
+.BR iswupper ()
+function returns nonzero if
+.I wc
+is a wide character
+belonging to the wide-character class "upper".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswupper ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswupper ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+This function is not very appropriate for dealing with Unicode characters,
+because Unicode knows about three cases: upper, lower, and title case.
+.SH SEE ALSO
+.BR isupper (3),
+.BR iswctype (3),
+.BR towupper (3)
diff --git a/man/man3/iswxdigit.3 b/man/man3/iswxdigit.3
new file mode 100644
index 000000000..427fc3751
--- /dev/null
+++ b/man/man3/iswxdigit.3
@@ -0,0 +1,87 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH iswxdigit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iswxdigit \- test for hexadecimal digit wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "int iswxdigit(wint_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR iswxdigit ()
+function is the wide-character equivalent of the
+.BR isxdigit (3)
+function.
+It tests whether
+.I wc
+is a wide character
+belonging to the wide-character class "xdigit".
+.P
+The wide-character class "xdigit" is a subclass of the wide-character class
+"alnum", and therefore also a subclass of the wide-character class "graph" and
+of the wide-character class "print".
+.P
+Being a subclass of the wide-character class "print", the wide-character class
+"xdigit" is disjoint from the wide-character class "cntrl".
+.P
+Being a subclass of the wide-character class "graph", the wide-character class
+"xdigit" is disjoint from the wide-character class "space" and its subclass
+"blank".
+.P
+Being a subclass of the wide-character class "alnum", the wide-character class
+"xdigit" is disjoint from the wide-character class "punct".
+.P
+The wide-character class "xdigit" always contains at least the
+letters \[aq]A\[aq] to \[aq]F\[aq], \[aq]a\[aq] to \[aq]f\[aq]
+and the digits \[aq]0\[aq] to \[aq]9\[aq].
+.SH RETURN VALUE
+The
+.BR iswxdigit ()
+function returns nonzero if
+.I wc
+is a wide character
+belonging to the wide-character class "xdigit".
+Otherwise, it returns zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR iswxdigit ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR iswxdigit ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR iswctype (3),
+.BR isxdigit (3)
diff --git a/man/man3/isxdigit.3 b/man/man3/isxdigit.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isxdigit.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/isxdigit_l.3 b/man/man3/isxdigit_l.3
new file mode 100644
index 000000000..0b69c7544
--- /dev/null
+++ b/man/man3/isxdigit_l.3
@@ -0,0 +1 @@
+.so man3/isalpha.3
diff --git a/man/man3/j0.3 b/man/man3/j0.3
new file mode 100644
index 000000000..d1af2938b
--- /dev/null
+++ b/man/man3/j0.3
@@ -0,0 +1,195 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:08:17 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-08-25, aeb
+.\" Modified 2004-11-12 as per suggestion by Fabian Kreutz/AEB
+.\" 2008-07-24, mtk, moved yxx() material into separate y0.3 page
+.\"
+.TH j0 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+j0, j0f, j0l, j1, j1f, j1l, jn, jnf, jnl \-
+Bessel functions of the first kind
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double j0(double " x );
+.BI "double j1(double " x );
+.BI "double jn(int " n ", double " x );
+.P
+.BI "float j0f(float " x );
+.BI "float j1f(float " x );
+.BI "float jnf(int " n ", float " x );
+.P
+.BI "long double j0l(long double " x );
+.BI "long double j1l(long double " x );
+.BI "long double jnl(int " n ", long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR j0 (),
+.BR j1 (),
+.BR jn ():
+.nf
+    _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.P
+.BR j0f (),
+.BR j0l (),
+.BR j1f (),
+.BR j1l (),
+.BR jnf (),
+.BR jnl ():
+.nf
+    _XOPEN_SOURCE >= 600
+        || (_ISOC99_SOURCE && _XOPEN_SOURCE)
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR j0 ()
+and
+.BR j1 ()
+functions return Bessel functions of
+.I x
+of the first kind of orders 0 and 1, respectively.
+The
+.BR jn ()
+function
+returns the Bessel function of
+.I x
+of the first kind of order
+.IR n .
+.P
+The
+.BR j0f (),
+.BR j1f (),
+and
+.BR jnf (),
+functions are versions that take and return
+.I float
+values.
+The
+.BR j0l (),
+.BR j1l (),
+and
+.BR jnl ()
+functions are versions that take and return
+.I "long double"
+values.
+.SH RETURN VALUE
+On success, these functions return the appropriate
+Bessel value of the first kind for
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is too large in magnitude,
+or the result underflows,
+a range error occurs,
+and the return value is 0.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result underflow, or \fIx\fP is too large in magnitude
+.I errno
+is set to
+.BR ERANGE .
+.P
+These functions do not raise exceptions for
+.BR fetestexcept (3).
+.\" e.g., j0(1.5e16)
+.\" This is intentional.
+.\" See https://www.sourceware.org/bugzilla/show_bug.cgi?id=6805
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR j0 (),
+.BR j0f (),
+.BR j0l ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR j1 (),
+.BR j1f (),
+.BR j1l ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR jn (),
+.BR jnf (),
+.BR jnl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR j0 ()
+.TQ
+.BR j1 ()
+.TQ
+.BR jn ()
+POSIX.1-2008.
+.TP
+Others:
+BSD.
+.SH HISTORY
+.TP
+.BR j0 ()
+.TQ
+.BR j1 ()
+.TQ
+.BR jn ()
+SVr4, 4.3BSD,
+POSIX.1-2001, POSIX.1-2008.
+.TP
+Others:
+BSD.
+.SH BUGS
+There are errors of up to 2e\-16 in the values returned by
+.BR j0 (),
+.BR j1 (),
+and
+.BR jn ()
+for values of
+.I x
+between \-8 and 8.
+.SH SEE ALSO
+.BR y0 (3)
diff --git a/man/man3/j0f.3 b/man/man3/j0f.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/j0f.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/j0l.3 b/man/man3/j0l.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/j0l.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/j1.3 b/man/man3/j1.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/j1.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/j1f.3 b/man/man3/j1f.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/j1f.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/j1l.3 b/man/man3/j1l.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/j1l.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/jn.3 b/man/man3/jn.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/jn.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/jnf.3 b/man/man3/jnf.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/jnf.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/jnl.3 b/man/man3/jnl.3
new file mode 100644
index 000000000..6dc181883
--- /dev/null
+++ b/man/man3/jnl.3
@@ -0,0 +1 @@
+.so man3/j0.3
diff --git a/man/man3/jrand48.3 b/man/man3/jrand48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/jrand48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/jrand48_r.3 b/man/man3/jrand48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/jrand48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/key_decryptsession.3 b/man/man3/key_decryptsession.3
new file mode 100644
index 000000000..bc4bb02b2
--- /dev/null
+++ b/man/man3/key_decryptsession.3
@@ -0,0 +1 @@
+.so man3/key_setsecret.3
diff --git a/man/man3/key_encryptsession.3 b/man/man3/key_encryptsession.3
new file mode 100644
index 000000000..bc4bb02b2
--- /dev/null
+++ b/man/man3/key_encryptsession.3
@@ -0,0 +1 @@
+.so man3/key_setsecret.3
diff --git a/man/man3/key_gendes.3 b/man/man3/key_gendes.3
new file mode 100644
index 000000000..bc4bb02b2
--- /dev/null
+++ b/man/man3/key_gendes.3
@@ -0,0 +1 @@
+.so man3/key_setsecret.3
diff --git a/man/man3/key_secretkey_is_set.3 b/man/man3/key_secretkey_is_set.3
new file mode 100644
index 000000000..bc4bb02b2
--- /dev/null
+++ b/man/man3/key_secretkey_is_set.3
@@ -0,0 +1 @@
+.so man3/key_setsecret.3
diff --git a/man/man3/key_setsecret.3 b/man/man3/key_setsecret.3
new file mode 100644
index 000000000..18bbb107b
--- /dev/null
+++ b/man/man3/key_setsecret.3
@@ -0,0 +1,87 @@
+'\" t
+.\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\"  I had no way the check the functions out
+.\"  be careful
+.TH key_setsecret 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+key_decryptsession, key_encryptsession, key_setsecret, key_gendes,
+key_secretkey_is_set \- interfaces to rpc keyserver daemon
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <rpc/rpc.h>
+.P
+.BI "int key_decryptsession(char *" remotename ", des_block *" deskey );
+.BI "int key_encryptsession(char *" remotename ", des_block *" deskey );
+.P
+.BI "int key_gendes(des_block *" deskey );
+.P
+.BI "int key_setsecret(char *" key );
+.B int key_secretkey_is_set(void);
+.fi
+.SH DESCRIPTION
+The functions here are used within the RPC's secure authentication
+mechanism (AUTH_DES).
+There should be no need for user programs to
+use this functions.
+.P
+The function
+.BR key_decryptsession ()
+uses the (remote) server netname and takes the DES key
+for decrypting.
+It uses the public key of the server and the
+secret key associated with the effective UID of the calling process.
+.P
+The function
+.BR key_encryptsession ()
+is the inverse of
+.BR key_decryptsession ().
+It encrypts the DES keys with the public key of the server and
+the secret key associated with the effective UID of the calling process.
+.P
+The function
+.BR key_gendes ()
+is used to ask the keyserver for a secure conversation key.
+.P
+The function
+.BR key_setsecret ()
+is used to set the key for the effective UID of the calling process.
+.P
+The function
+.BR key_secretkey_is_set ()
+can be used to determine whether a key has been
+set for the effective UID of the calling process.
+.SH RETURN VALUE
+These functions return 1 on success and 0 on failure.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR key_decryptsession (),
+.BR key_encryptsession (),
+.BR key_gendes (),
+.BR key_setsecret (),
+.BR key_secretkey_is_set ()
+T}	Thread safety	MT-Safe
+.TE
+.SH NOTES
+Note that we talk about two types of encryption here.
+One is asymmetric using a public and secret key.
+The other is symmetric, the
+64-bit DES.
+.P
+These routines were part of the Linux/Doors-project, abandoned by now.
+.SH SEE ALSO
+.BR crypt (3)
diff --git a/man/man3/killpg.3 b/man/man3/killpg.3
new file mode 100644
index 000000000..bec05d8be
--- /dev/null
+++ b/man/man3/killpg.3
@@ -0,0 +1,113 @@
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)killpg.2	6.5 (Berkeley) 3/10/91
+.\"
+.\" Modified Fri Jul 23 21:55:01 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified 2004-06-16 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on CAP_KILL
+.\" Modified 2004-06-21 by aeb
+.\"
+.TH killpg 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+killpg \- send signal to a process group
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int killpg(int " pgrp ", int " sig );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR killpg ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR killpg ()
+sends the signal
+.I sig
+to the process group
+.IR pgrp .
+See
+.BR signal (7)
+for a list of signals.
+.P
+If
+.I pgrp
+is 0,
+.BR killpg ()
+sends the signal to the calling process's process group.
+(POSIX says: if
+.I pgrp
+is less than or equal to 1, the behavior is undefined.)
+.P
+For the permissions required to send a signal to another process, see
+.BR kill (2).
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I sig
+is not a valid signal number.
+.TP
+.B EPERM
+The process does not have permission to send the signal
+to any of the target processes.
+For the required permissions, see
+.BR kill (2).
+.TP
+.B ESRCH
+No process can be found in the process group specified by
+.IR pgrp .
+.TP
+.B ESRCH
+The process group was given as 0 but the sending process does not
+have a process group.
+.SH VERSIONS
+There are various differences between the permission checking
+in BSD-type systems and System\ V-type systems.
+See the POSIX rationale for
+.BR kill (3p).
+A difference not mentioned by POSIX concerns the return
+value
+.BR EPERM :
+BSD documents that no signal is sent and
+.B EPERM
+returned when the permission check failed for at least one target process,
+while POSIX documents
+.B EPERM
+only when the permission check failed for all target processes.
+.SS C library/kernel differences
+On Linux,
+.BR killpg ()
+is implemented as a library function that makes the call
+.IR "kill(\-pgrp,\ sig)" .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.4BSD
+(first appeared in 4BSD).
+.SH SEE ALSO
+.BR getpgrp (2),
+.BR kill (2),
+.BR signal (2),
+.BR capabilities (7),
+.BR credentials (7)
diff --git a/man/man3/klogctl.3 b/man/man3/klogctl.3
new file mode 100644
index 000000000..bbe6ab283
--- /dev/null
+++ b/man/man3/klogctl.3
@@ -0,0 +1 @@
+.so man2/syslog.2
diff --git a/man/man3/l64a.3 b/man/man3/l64a.3
new file mode 100644
index 000000000..e54ce2724
--- /dev/null
+++ b/man/man3/l64a.3
@@ -0,0 +1 @@
+.so man3/a64l.3
diff --git a/man/man3/labs.3 b/man/man3/labs.3
new file mode 100644
index 000000000..97db8d2b6
--- /dev/null
+++ b/man/man3/labs.3
@@ -0,0 +1 @@
+.so man3/abs.3
diff --git a/man/man3/lckpwdf.3 b/man/man3/lckpwdf.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/lckpwdf.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/lcong48.3 b/man/man3/lcong48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/lcong48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/lcong48_r.3 b/man/man3/lcong48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/lcong48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/ldexp.3 b/man/man3/ldexp.3
new file mode 100644
index 000000000..d361beb1f
--- /dev/null
+++ b/man/man3/ldexp.3
@@ -0,0 +1,131 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2004-10-31 by aeb
+.\"
+.TH ldexp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ldexp, ldexpf, ldexpl \- multiply floating-point number by integral power of 2
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double ldexp(double " x ", int " exp );
+.BI "float ldexpf(float " x ", int " exp );
+.BI "long double ldexpl(long double " x ", int " exp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ldexpf (),
+.BR ldexpl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the result of multiplying the floating-point number
+.I x
+by 2 raised to the power
+.IR exp .
+.SH RETURN VALUE
+On success, these functions return
+.IR "x * (2\[ha]exp)" .
+.P
+If
+.I exp
+is zero, then
+.I x
+is returned.
+.P
+If
+.I x
+is a NaN,
+a NaN is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity),
+positive infinity (negative infinity) is returned.
+.P
+If the result underflows,
+a range error occurs,
+and zero is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with a sign the same as
+.IR x .
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error, overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error, underflow
+.I errno
+is set to
+.BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ldexp (),
+.BR ldexpf (),
+.BR ldexpl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR frexp (3),
+.BR modf (3),
+.BR scalbln (3)
diff --git a/man/man3/ldexpf.3 b/man/man3/ldexpf.3
new file mode 100644
index 000000000..0e74a023e
--- /dev/null
+++ b/man/man3/ldexpf.3
@@ -0,0 +1 @@
+.so man3/ldexp.3
diff --git a/man/man3/ldexpl.3 b/man/man3/ldexpl.3
new file mode 100644
index 000000000..0e74a023e
--- /dev/null
+++ b/man/man3/ldexpl.3
@@ -0,0 +1 @@
+.so man3/ldexp.3
diff --git a/man/man3/ldiv.3 b/man/man3/ldiv.3
new file mode 100644
index 000000000..934824e3e
--- /dev/null
+++ b/man/man3/ldiv.3
@@ -0,0 +1 @@
+.so man3/div.3
diff --git a/man/man3/le16toh.3 b/man/man3/le16toh.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/le16toh.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/le32toh.3 b/man/man3/le32toh.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/le32toh.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/le64toh.3 b/man/man3/le64toh.3
new file mode 100644
index 000000000..8b7bc7715
--- /dev/null
+++ b/man/man3/le64toh.3
@@ -0,0 +1 @@
+.so man3/endian.3
diff --git a/man/man3/lfind.3 b/man/man3/lfind.3
new file mode 100644
index 000000000..24179b4d9
--- /dev/null
+++ b/man/man3/lfind.3
@@ -0,0 +1 @@
+.so man3/lsearch.3
diff --git a/man/man3/lgamma.3 b/man/man3/lgamma.3
new file mode 100644
index 000000000..87b8ec3ff
--- /dev/null
+++ b/man/man3/lgamma.3
@@ -0,0 +1,202 @@
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" based on glibc infopages
+.\"
+.TH lgamma 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lgamma, lgammaf, lgammal, lgamma_r, lgammaf_r, lgammal_r, signgam \-
+log gamma function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double lgamma(double " x );
+.BI "float lgammaf(float " x );
+.BI "long double lgammal(long double " x );
+.P
+.BI "double lgamma_r(double " x ", int *" signp );
+.BI "float lgammaf_r(float " x ", int *" signp );
+.BI "long double lgammal_r(long double " x ", int *" signp );
+.P
+.BI "extern int " signgam ;
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.nf
+.BR lgamma ():
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR lgammaf (),
+.BR lgammal ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR lgamma_r (),
+.BR lgammaf_r (),
+.BR lgammal_r ():
+.nf
+    /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.IR signgam :
+.nf
+    _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+For the definition of the Gamma function, see
+.BR tgamma (3).
+.P
+The
+.BR lgamma (),
+.BR lgammaf (),
+and
+.BR lgammal ()
+functions return the natural logarithm of
+the absolute value of the Gamma function.
+The sign of the Gamma function is returned in the
+external integer
+.I signgam
+declared in
+.IR <math.h> .
+It is 1 when the Gamma function is positive or zero, \-1
+when it is negative.
+.P
+Since using a constant location
+.I signgam
+is not thread-safe, the functions
+.BR lgamma_r (),
+.BR lgammaf_r (),
+and
+.BR lgammal_r ()
+have been introduced; they return the sign via the argument
+.IR signp .
+.SH RETURN VALUE
+On success, these functions return the natural logarithm of Gamma(x).
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is 1 or 2, +0 is returned.
+.P
+If
+.I x
+is positive infinity or negative infinity,
+positive infinity is returned.
+.P
+If
+.I x
+is a nonpositive integer,
+a pole error occurs,
+and the functions return
+.RB + HUGE_VAL ,
+.RB + HUGE_VALF ,
+or
+.RB + HUGE_VALL ,
+respectively.
+.P
+If the result overflows,
+a range error occurs,
+.\" e.g., lgamma(DBL_MAX)
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the correct mathematical sign.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Pole error: \fIx\fP is a nonpositive integer
+.I errno
+is set to
+.B ERANGE
+(but see BUGS).
+A divide-by-zero floating-point exception
+.RB ( FE_DIVBYZERO )
+is raised.
+.TP
+Range error: result overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.\" glibc (as at 2.8) also supports an inexact
+.\" exception for various cases.
+.SH STANDARDS
+.TP
+.BR lgamma ()
+.TQ
+.BR lgammaf ()
+.TQ
+.BR lgammal ()
+C11, POSIX.1-2008.
+.TP
+.I signgam
+POSIX.1-2008.
+.TP
+.BR lgamma_r ()
+.TQ
+.BR lgammaf_r ()
+.TQ
+.BR lgammal_r ()
+None.
+.SH HISTORY
+.TP
+.BR lgamma ()
+.TQ
+.BR lgammaf ()
+.TQ
+.BR lgammal ()
+C99, POSIX.1-2001.
+.TP
+.I signgam
+POSIX.1-2001.
+.TP
+.BR lgamma_r ()
+.TQ
+.BR lgammaf_r ()
+.TQ
+.BR lgammal_r ()
+None.
+.SH BUGS
+In glibc 2.9 and earlier,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6777
+when a pole error occurs,
+.I errno
+is set to
+.BR EDOM ;
+instead of the POSIX-mandated
+.BR ERANGE .
+Since glibc 2.10, glibc does the right thing.
+.SH SEE ALSO
+.BR tgamma (3)
diff --git a/man/man3/lgamma_r.3 b/man/man3/lgamma_r.3
new file mode 100644
index 000000000..be0ed98e0
--- /dev/null
+++ b/man/man3/lgamma_r.3
@@ -0,0 +1 @@
+.so man3/lgamma.3
diff --git a/man/man3/lgammaf.3 b/man/man3/lgammaf.3
new file mode 100644
index 000000000..be0ed98e0
--- /dev/null
+++ b/man/man3/lgammaf.3
@@ -0,0 +1 @@
+.so man3/lgamma.3
diff --git a/man/man3/lgammaf_r.3 b/man/man3/lgammaf_r.3
new file mode 100644
index 000000000..be0ed98e0
--- /dev/null
+++ b/man/man3/lgammaf_r.3
@@ -0,0 +1 @@
+.so man3/lgamma.3
diff --git a/man/man3/lgammal.3 b/man/man3/lgammal.3
new file mode 100644
index 000000000..be0ed98e0
--- /dev/null
+++ b/man/man3/lgammal.3
@@ -0,0 +1 @@
+.so man3/lgamma.3
diff --git a/man/man3/lgammal_r.3 b/man/man3/lgammal_r.3
new file mode 100644
index 000000000..be0ed98e0
--- /dev/null
+++ b/man/man3/lgammal_r.3
@@ -0,0 +1 @@
+.so man3/lgamma.3
diff --git a/man/man3/lio_listio.3 b/man/man3/lio_listio.3
new file mode 100644
index 000000000..bd9367d7c
--- /dev/null
+++ b/man/man3/lio_listio.3
@@ -0,0 +1,224 @@
+'\" t
+.\" Copyright (C) 2010, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH lio_listio 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lio_listio \- initiate a list of I/O requests
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B "#include <aio.h>"
+.P
+.BI "int lio_listio(int " mode ,
+.BI "               struct aiocb *restrict const " aiocb_list [restrict],
+.BI "               int " nitems ", struct sigevent *restrict " sevp );
+.fi
+.SH DESCRIPTION
+The
+.BR lio_listio ()
+function initiates the list of I/O operations described by the array
+.IR aiocb_list .
+.P
+The
+.I mode
+operation has one of the following values:
+.TP
+.B LIO_WAIT
+The call blocks until all operations are complete.
+The
+.I sevp
+argument is ignored.
+.TP
+.B LIO_NOWAIT
+The I/O operations are queued for processing and the call returns immediately.
+When all of the I/O operations complete, asynchronous notification occurs,
+as specified by the
+.I sevp
+argument; see
+.BR sigevent (3type)
+for details.
+If
+.I sevp
+is NULL, no asynchronous notification occurs.
+.P
+The
+.I aiocb_list
+argument is an array of pointers to
+.I aiocb
+structures that describe I/O operations.
+These operations are executed in an unspecified order.
+The
+.I nitems
+argument specifies the size of the array
+.IR aiocb_list .
+Null pointers in
+.I aiocb_list
+are ignored.
+.P
+In each control block in
+.IR aiocb_list ,
+the
+.I aio_lio_opcode
+field specifies the I/O operation to be initiated, as follows:
+.TP
+.B LIO_READ
+Initiate a read operation.
+The operation is queued as for a call to
+.BR aio_read (3)
+specifying this control block.
+.TP
+.B LIO_WRITE
+Initiate a write operation.
+The operation is queued as for a call to
+.BR aio_write (3)
+specifying this control block.
+.TP
+.B LIO_NOP
+Ignore this control block.
+.P
+The remaining fields in each control block have the same meanings as for
+.BR aio_read (3)
+and
+.BR aio_write (3).
+The
+.I aio_sigevent
+fields of each control block can be used to specify notifications
+for the individual I/O operations (see
+.BR sigevent (7)).
+.SH RETURN VALUE
+If
+.I mode
+is
+.BR LIO_NOWAIT ,
+.BR lio_listio ()
+returns 0 if all I/O operations are successfully queued.
+Otherwise, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+If
+.I mode
+is
+.BR LIO_WAIT ,
+.BR lio_listio ()
+returns 0 when all of the I/O operations have completed successfully.
+Otherwise, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+The return status from
+.BR lio_listio ()
+provides information only about the call itself,
+not about the individual I/O operations.
+One or more of the I/O operations may fail,
+but this does not prevent other operations completing.
+The status of individual I/O operations in
+.I aiocb_list
+can be determined using
+.BR aio_error (3).
+When an operation has completed,
+its return status can be obtained using
+.BR aio_return (3).
+Individual I/O operations can fail for the reasons described in
+.BR aio_read (3)
+and
+.BR aio_write (3).
+.SH ERRORS
+The
+.BR lio_listio ()
+function may fail for the following reasons:
+.TP
+.B EAGAIN
+Out of resources.
+.TP
+.B EAGAIN
+.\" Doesn't happen in glibc(?)
+The number of I/O operations specified by
+.I nitems
+would cause the limit
+.B AIO_MAX
+to be exceeded.
+.TP
+.B EINTR
+.I mode
+was
+.B LIO_WAIT
+and a signal
+was caught before all I/O operations completed; see
+.BR signal (7).
+(This may even be one of the signals used for
+asynchronous I/O completion notification.)
+.TP
+.B EINVAL
+.I mode
+is invalid, or
+.\" Doesn't happen in glibc(?)
+.I nitems
+exceeds the limit
+.BR AIO_LISTIO_MAX .
+.TP
+.B EIO
+One of more of the operations specified by
+.I aiocb_list
+failed.
+.\" e.g., ioa_reqprio or aio_lio_opcode was invalid
+The application can check the status of each operation using
+.BR aio_return (3).
+.P
+If
+.BR lio_listio ()
+fails with the error
+.BR EAGAIN ,
+.BR EINTR ,
+or
+.BR EIO ,
+then some of the operations in
+.I aiocb_list
+may have been initiated.
+If
+.BR lio_listio ()
+fails for any other reason,
+then none of the I/O operations has been initiated.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR lio_listio ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH NOTES
+It is a good idea to zero out the control blocks before use.
+The control blocks must not be changed while the I/O operations
+are in progress.
+The buffer areas being read into or written from
+.\" or the control block of the operation
+must not be accessed during the operations or undefined results may occur.
+The memory areas involved must remain valid.
+.P
+Simultaneous I/O operations specifying the same
+.I aiocb
+structure produce undefined results.
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_fsync (3),
+.BR aio_return (3),
+.BR aio_suspend (3),
+.BR aio_write (3),
+.BR aio (7)
diff --git a/man/man3/list.3 b/man/man3/list.3
new file mode 100644
index 000000000..6f33dbf99
--- /dev/null
+++ b/man/man3/list.3
@@ -0,0 +1,308 @@
+.\" Copyright (c) 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\" and Copyright (c) 2020 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"
+.TH LIST 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+LIST_EMPTY,
+LIST_ENTRY,
+LIST_FIRST,
+LIST_FOREACH,
+.\"LIST_FOREACH_FROM,
+.\"LIST_FOREACH_SAFE,
+.\"LIST_FOREACH_FROM_SAFE,
+LIST_HEAD,
+LIST_HEAD_INITIALIZER,
+LIST_INIT,
+LIST_INSERT_AFTER,
+LIST_INSERT_BEFORE,
+LIST_INSERT_HEAD,
+LIST_NEXT,
+.\"LIST_PREV,
+LIST_REMOVE
+.\"LIST_SWAP
+\- implementation of a doubly linked list
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/queue.h>
+.P
+.B LIST_ENTRY(TYPE);
+.P
+.B LIST_HEAD(HEADNAME, TYPE);
+.BI "LIST_HEAD LIST_HEAD_INITIALIZER(LIST_HEAD " head );
+.BI "void LIST_INIT(LIST_HEAD *" head );
+.P
+.BI "int LIST_EMPTY(LIST_HEAD *" head );
+.P
+.BI "void LIST_INSERT_HEAD(LIST_HEAD *" head ,
+.BI "                        struct TYPE *" elm ", LIST_ENTRY " NAME );
+.BI "void LIST_INSERT_BEFORE(struct TYPE *" listelm ,
+.BI "                        struct TYPE *" elm ", LIST_ENTRY " NAME );
+.BI "void LIST_INSERT_AFTER(struct TYPE *" listelm ,
+.BI "                        struct TYPE *" elm ", LIST_ENTRY " NAME );
+.P
+.BI "struct TYPE *LIST_FIRST(LIST_HEAD *" head );
+.\" .BI "struct TYPE *LIST_PREV(struct TYPE *" elm ", LIST_HEAD *" head ,
+.\" .BI "                        struct TYPE, LIST_ENTRY " NAME );
+.BI "struct TYPE *LIST_NEXT(struct TYPE *" elm ", LIST_ENTRY " NAME );
+.P
+.BI "LIST_FOREACH(struct TYPE *" var ", LIST_HEAD *" head ", LIST_ENTRY " NAME );
+.\" .BI "LIST_FOREACH_FROM(struct TYPE *" var ", LIST_HEAD *" head ", LIST_ENTRY " NAME );
+.\" .P
+.\" .BI "LIST_FOREACH_SAFE(struct TYPE *" var ", LIST_HEAD *" head ,
+.\" .BI "                        LIST_ENTRY " NAME ", struct TYPE *" temp_var );
+.\" .BI "LIST_FOREACH_FROM_SAFE(struct TYPE *" var ", LIST_HEAD *" head ,
+.\" .BI "                        LIST_ENTRY " NAME ", struct TYPE *" temp_var );
+.P
+.BI "void LIST_REMOVE(struct TYPE *" elm ", LIST_ENTRY " NAME );
+.\" .P
+.\" .BI "void LIST_SWAP(LIST_HEAD *" head1 ", LIST_HEAD *" head2 ,
+.\" .BI "                        struct TYPE, LIST_ENTRY " NAME );
+.fi
+.SH DESCRIPTION
+These macros define and operate on doubly linked lists.
+.P
+In the macro definitions,
+.I TYPE
+is the name of a user-defined structure,
+that must contain a field of type
+.IR LIST_ENTRY ,
+named
+.IR NAME .
+The argument
+.I HEADNAME
+is the name of a user-defined structure
+that must be declared using the macro
+.BR LIST_HEAD ().
+.SS Creation
+A list is headed by a structure defined by the
+.BR LIST_HEAD ()
+macro.
+This structure contains a single pointer to the first element on the list.
+The elements are doubly linked
+so that an arbitrary element can be removed without traversing the list.
+New elements can be added to the list
+after an existing element,
+before an existing element,
+or at the head of the list.
+A
+.I LIST_HEAD
+structure is declared as follows:
+.P
+.in +4
+.EX
+LIST_HEAD(HEADNAME, TYPE) head;
+.EE
+.in
+.P
+where
+.I struct HEADNAME
+is the structure to be defined, and
+.I struct TYPE
+is the type of the elements to be linked into the list.
+A pointer to the head of the list can later be declared as:
+.P
+.in +4
+.EX
+struct HEADNAME *headp;
+.EE
+.in
+.P
+(The names
+.I head
+and
+.I headp
+are user selectable.)
+.P
+.BR LIST_ENTRY ()
+declares a structure that connects the elements in the list.
+.P
+.BR LIST_HEAD_INITIALIZER ()
+evaluates to an initializer for the list
+.IR head .
+.P
+.BR LIST_INIT ()
+initializes the list referenced by
+.IR head .
+.P
+.BR LIST_EMPTY ()
+evaluates to true if there are no elements in the list.
+.SS Insertion
+.BR LIST_INSERT_HEAD ()
+inserts the new element
+.I elm
+at the head of the list.
+.P
+.BR LIST_INSERT_BEFORE ()
+inserts the new element
+.I elm
+before the element
+.IR listelm .
+.P
+.BR LIST_INSERT_AFTER ()
+inserts the new element
+.I elm
+after the element
+.IR listelm .
+.SS Traversal
+.BR LIST_FIRST ()
+returns the first element in the list, or NULL if the list is empty.
+.\" .P
+.\" .BR LIST_PREV ()
+.\" returns the previous element in the list, or NULL if this is the first.
+.\" List
+.\" .I head
+.\" must contain element
+.\" .IR elm .
+.P
+.BR LIST_NEXT ()
+returns the next element in the list, or NULL if this is the last.
+.P
+.BR LIST_FOREACH ()
+traverses the list referenced by
+.I head
+in the forward direction,
+assigning each element in turn to
+.IR var .
+.\" .P
+.\" .BR LIST_FOREACH_FROM ()
+.\" behaves identically to
+.\" .BR LIST_FOREACH ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found LIST element and begins the loop at
+.\" .I var
+.\" instead of the first element in the LIST referenced by
+.\" .IR head .
+.\" .P
+.\" .BR LIST_FOREACH_SAFE ()
+.\" traverses the list referenced by
+.\" .I head
+.\" in the forward direction, assigning each element in turn to
+.\" .IR var .
+.\" However, unlike
+.\" .BR LIST_FOREACH ()
+.\" here it is permitted to both remove
+.\" .I var
+.\" as well as free it from within the loop safely without interfering with the
+.\" traversal.
+.\" .P
+.\" .BR LIST_FOREACH_FROM_SAFE ()
+.\" behaves identically to
+.\" .BR LIST_FOREACH_SAFE ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found LIST element and begins the loop at
+.\" .I var
+.\" instead of the first element in the LIST referenced by
+.\" .IR head .
+.SS Removal
+.BR LIST_REMOVE ()
+removes the element
+.I elm
+from the list.
+.\" .SS Other features
+.\" .BR LIST_SWAP ()
+.\" swaps the contents of
+.\" .I head1
+.\" and
+.\" .IR head2 .
+.SH RETURN VALUE
+.BR LIST_EMPTY ()
+returns nonzero if the list is empty,
+and zero if the list contains at least one entry.
+.P
+.BR LIST_FIRST (),
+and
+.BR LIST_NEXT ()
+return a pointer to the first or next
+.I TYPE
+structure, respectively.
+.P
+.BR LIST_HEAD_INITIALIZER ()
+returns an initializer that can be assigned to the list
+.IR head .
+.SH STANDARDS
+BSD.
+.SH HISTORY
+4.4BSD.
+.SH BUGS
+.BR LIST_FOREACH ()
+doesn't allow
+.I var
+to be removed or freed within the loop,
+as it would interfere with the traversal.
+.BR LIST_FOREACH_SAFE (),
+which is present on the BSDs but is not present in glibc,
+fixes this limitation by allowing
+.I var
+to safely be removed from the list and freed from within the loop
+without interfering with the traversal.
+.SH EXAMPLES
+.\" SRC BEGIN (list.c)
+.EX
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/queue.h>
+\&
+struct entry {
+    int data;
+    LIST_ENTRY(entry) entries;              /* List */
+};
+\&
+LIST_HEAD(listhead, entry);
+\&
+int
+main(void)
+{
+    struct entry *n1, *n2, *n3, *np;
+    struct listhead head;                   /* List head */
+    int i;
+\&
+    LIST_INIT(&head);                       /* Initialize the list */
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the head */
+    LIST_INSERT_HEAD(&head, n1, entries);
+\&
+    n2 = malloc(sizeof(struct entry));      /* Insert after */
+    LIST_INSERT_AFTER(n1, n2, entries);
+\&
+    n3 = malloc(sizeof(struct entry));      /* Insert before */
+    LIST_INSERT_BEFORE(n2, n3, entries);
+\&
+    i = 0;                                  /* Forward traversal */
+    LIST_FOREACH(np, &head, entries)
+        np\->data = i++;
+\&
+    LIST_REMOVE(n2, entries);               /* Deletion */
+    free(n2);
+                                            /* Forward traversal */
+    LIST_FOREACH(np, &head, entries)
+        printf("%i\en", np\->data);
+                                            /* List deletion */
+    n1 = LIST_FIRST(&head);
+    while (n1 != NULL) {
+        n2 = LIST_NEXT(n1, entries);
+        free(n1);
+        n1 = n2;
+    }
+    LIST_INIT(&head);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR insque (3),
+.BR queue (7)
diff --git a/man/man3/llabs.3 b/man/man3/llabs.3
new file mode 100644
index 000000000..97db8d2b6
--- /dev/null
+++ b/man/man3/llabs.3
@@ -0,0 +1 @@
+.so man3/abs.3
diff --git a/man/man3/lldiv.3 b/man/man3/lldiv.3
new file mode 100644
index 000000000..934824e3e
--- /dev/null
+++ b/man/man3/lldiv.3
@@ -0,0 +1 @@
+.so man3/div.3
diff --git a/man/man3/llrint.3 b/man/man3/llrint.3
new file mode 100644
index 000000000..d1c0af3b8
--- /dev/null
+++ b/man/man3/llrint.3
@@ -0,0 +1 @@
+.so man3/lrint.3
diff --git a/man/man3/llrintf.3 b/man/man3/llrintf.3
new file mode 100644
index 000000000..d1c0af3b8
--- /dev/null
+++ b/man/man3/llrintf.3
@@ -0,0 +1 @@
+.so man3/lrint.3
diff --git a/man/man3/llrintl.3 b/man/man3/llrintl.3
new file mode 100644
index 000000000..d1c0af3b8
--- /dev/null
+++ b/man/man3/llrintl.3
@@ -0,0 +1 @@
+.so man3/lrint.3
diff --git a/man/man3/llround.3 b/man/man3/llround.3
new file mode 100644
index 000000000..bcc9b0fda
--- /dev/null
+++ b/man/man3/llround.3
@@ -0,0 +1 @@
+.so man3/lround.3
diff --git a/man/man3/llroundf.3 b/man/man3/llroundf.3
new file mode 100644
index 000000000..bcc9b0fda
--- /dev/null
+++ b/man/man3/llroundf.3
@@ -0,0 +1 @@
+.so man3/lround.3
diff --git a/man/man3/llroundl.3 b/man/man3/llroundl.3
new file mode 100644
index 000000000..bcc9b0fda
--- /dev/null
+++ b/man/man3/llroundl.3
@@ -0,0 +1 @@
+.so man3/lround.3
diff --git a/man/man3/localeconv.3 b/man/man3/localeconv.3
new file mode 100644
index 000000000..4862c9c53
--- /dev/null
+++ b/man/man3/localeconv.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 19:01:20 1993 by Rik Faith (faith@cs.unc.edu)
+.TH localeconv 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+localeconv \- get numeric formatting information
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <locale.h>
+.P
+.B struct lconv *localeconv(void);
+.fi
+.SH DESCRIPTION
+The
+.BR localeconv ()
+function returns a pointer to a
+.I struct lconv
+for the current locale.
+This structure is shown in
+.BR locale (7),
+and contains all values associated with the locale categories
+.B LC_NUMERIC
+and
+.BR LC_MONETARY .
+Programs may also use the functions
+.BR printf (3)
+and
+.BR strfmon (3),
+which behave according to the actual locale in use.
+.SH RETURN VALUE
+The
+.BR localeconv ()
+function returns a pointer to a filled in
+.IR "struct lconv" .
+This structure may be (in glibc,
+.IR is )
+statically allocated, and may be overwritten by subsequent calls.
+According to POSIX,
+the caller should not modify the contents of this structure.
+The
+.BR localeconv ()
+function always succeeds.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR localeconv ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:localeconv locale
+T}
+.TE
+.SH STANDARDS
+C11.
+.SH HISTORY
+C89.
+.SH BUGS
+The
+.BR printf (3)
+family of functions may or may not honor the current locale.
+.SH SEE ALSO
+.BR locale (1),
+.BR localedef (1),
+.BR isalpha (3),
+.BR nl_langinfo (3),
+.BR setlocale (3),
+.BR strcoll (3),
+.BR strftime (3),
+.BR locale (7)
diff --git a/man/man3/localtime.3 b/man/man3/localtime.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/localtime.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/localtime_r.3 b/man/man3/localtime_r.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/localtime_r.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/lockf.3 b/man/man3/lockf.3
new file mode 100644
index 000000000..7267587c4
--- /dev/null
+++ b/man/man3/lockf.3
@@ -0,0 +1,179 @@
+'\" t
+.\" Copyright 1997 Nicolás Lichtmaier <nick@debian.org>
+.\" Created Thu Aug  7 00:44:00 ART 1997
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Added section stuff, aeb, 2002-04-22.
+.\" Corrected include file, drepper, 2003-06-15.
+.\"
+.TH lockf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lockf \- apply, test or remove a POSIX lock on an open file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int lockf(int " fd ", int " op ", off_t " len );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR lockf ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+Apply, test, or remove a POSIX lock on a section of an open file.
+The file is specified by
+.IR fd ,
+a file descriptor open for writing, the action by
+.IR op ,
+and the section consists of byte positions
+.IR pos .. pos + len \-1
+if
+.I len
+is positive, and
+.IR pos \- len .. pos \-1
+if
+.I len
+is negative, where
+.I pos
+is the current file position, and if
+.I len
+is zero, the section extends from the current file position to
+infinity, encompassing the present and future end-of-file positions.
+In all cases, the section may extend past current end-of-file.
+.P
+On Linux,
+.BR lockf ()
+is just an interface on top of
+.BR fcntl (2)
+locking.
+Many other systems implement
+.BR lockf ()
+in this way, but note that POSIX.1 leaves the relationship between
+.BR lockf ()
+and
+.BR fcntl (2)
+locks unspecified.
+A portable application should probably avoid mixing calls
+to these interfaces.
+.P
+Valid operations are given below:
+.TP
+.B F_LOCK
+Set an exclusive lock on the specified section of the file.
+If (part of) this section is already locked, the call
+blocks until the previous lock is released.
+If this section overlaps an earlier locked section,
+both are merged.
+File locks are released as soon as the process holding the locks
+closes some file descriptor for the file.
+A child process does not inherit these locks.
+.TP
+.B F_TLOCK
+Same as
+.B F_LOCK
+but the call never blocks and returns an error instead if the file is
+already locked.
+.TP
+.B F_ULOCK
+Unlock the indicated section of the file.
+This may cause a locked section to be split into two locked sections.
+.TP
+.B F_TEST
+Test the lock: return 0 if the specified section
+is unlocked or locked by this process; return \-1, set
+.I errno
+to
+.B EAGAIN
+.RB ( EACCES
+on some other systems),
+if another process holds a lock.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.BR EACCES " or " EAGAIN
+The file is locked and
+.B F_TLOCK
+or
+.B F_TEST
+was specified, or the operation is prohibited because the file has
+been memory-mapped by another process.
+.TP
+.B EBADF
+.I fd
+is not an open file descriptor; or
+.I op
+is
+.B F_LOCK
+or
+.B F_TLOCK
+and
+.I fd
+is not a writable file descriptor.
+.TP
+.B EDEADLK
+.I op
+was
+.B F_LOCK
+and this lock operation would cause a deadlock.
+.TP
+.B EINTR
+While waiting to acquire a lock, the call was interrupted by
+delivery of a signal caught by a handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+An invalid operation was specified in
+.IR op .
+.TP
+.B ENOLCK
+Too many segment locks open, lock table is full.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR lockf ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4.
+.SH SEE ALSO
+.BR fcntl (2),
+.BR flock (2)
+.P
+.I locks.txt
+and
+.I mandatory\-locking.txt
+in the Linux kernel source directory
+.I Documentation/filesystems
+(on older kernels, these files are directly under the
+.I Documentation
+directory, and
+.I mandatory\-locking.txt
+is called
+.IR mandatory.txt )
diff --git a/man/man3/log.3 b/man/man3/log.3
new file mode 100644
index 000000000..2192a9294
--- /dev/null
+++ b/man/man3/log.3
@@ -0,0 +1,140 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH log 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+log, logf, logl \- natural logarithmic function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double log(double " x );
+.BI "float logf(float " x );
+.BI "long double logl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR logf (),
+.BR logl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the natural logarithm of
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the natural logarithm of
+.IR x .
+.P
+If
+.I x
+is a NaN,
+a NaN is returned.
+.P
+If
+.I x
+is 1, the result is +0.
+.P
+If
+.I x
+is positive infinity,
+positive infinity is returned.
+.P
+If
+.I x
+is zero,
+then a pole error occurs, and the functions return
+.RB \- HUGE_VAL ,
+.RB \- HUGE_VALF ,
+or
+.RB \- HUGE_VALL ,
+respectively.
+.P
+If
+.I x
+is negative (including negative infinity), then
+a domain error occurs, and a NaN (not a number) is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is negative
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Pole error: \fIx\fP is zero
+.I errno
+is set to
+.BR ERANGE .
+A divide-by-zero floating-point exception
+.RB ( FE_DIVBYZERO )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR log (),
+.BR logf (),
+.BR logl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH BUGS
+In glibc 2.5 and earlier,
+taking the
+.BR log ()
+of a NaN produces a bogus invalid floating-point
+.RB ( FE_INVALID )
+exception.
+.SH SEE ALSO
+.BR cbrt (3),
+.BR clog (3),
+.BR log10 (3),
+.BR log1p (3),
+.BR log2 (3),
+.BR sqrt (3)
diff --git a/man/man3/log10.3 b/man/man3/log10.3
new file mode 100644
index 000000000..40e43117a
--- /dev/null
+++ b/man/man3/log10.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH log10 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+log10, log10f, log10l \-  base-10 logarithmic function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double log10(double " x );
+.BI "float log10f(float " x );
+.BI "long double log10l(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR log10f (),
+.BR log10l ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the base-10 logarithm of
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the base-10 logarithm of
+.IR x .
+.P
+For special cases, including where
+.I x
+is 0, 1, negative, infinity, or NaN, see
+.BR log (3).
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+For a discussion of the errors that can occur for these functions, see
+.BR log (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR log10 (),
+.BR log10f (),
+.BR log10l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR cbrt (3),
+.BR clog10 (3),
+.BR exp10 (3),
+.BR log (3),
+.BR log2 (3),
+.BR sqrt (3)
diff --git a/man/man3/log10f.3 b/man/man3/log10f.3
new file mode 100644
index 000000000..dfa5796ed
--- /dev/null
+++ b/man/man3/log10f.3
@@ -0,0 +1 @@
+.so man3/log10.3
diff --git a/man/man3/log10l.3 b/man/man3/log10l.3
new file mode 100644
index 000000000..dfa5796ed
--- /dev/null
+++ b/man/man3/log10l.3
@@ -0,0 +1 @@
+.so man3/log10.3
diff --git a/man/man3/log1p.3 b/man/man3/log1p.3
new file mode 100644
index 000000000..7855e6772
--- /dev/null
+++ b/man/man3/log1p.3
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright 1995 Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.TH log1p 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+log1p, log1pf, log1pl \-  logarithm of 1 plus argument
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double log1p(double " x );
+.BI "float log1pf(float " x );
+.BI "long double log1pl(long double " x );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.nf
+.BR log1p ():
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR log1pf (),
+.BR log1pl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return a value equivalent to
+.P
+.nf
+    log (1 + \fIx\fP)
+.fi
+.P
+The result is computed in a way
+that is accurate even if the value of
+.I x
+is near zero.
+.SH RETURN VALUE
+On success, these functions return the natural logarithm of
+.IR "(1\ +\ x)" .
+.P
+If
+.I x
+is a NaN,
+a NaN is returned.
+.P
+If
+.I x
+is positive infinity, positive infinity is returned.
+.P
+If
+.I x
+is \-1, a pole error occurs,
+and the functions return
+.RB \- HUGE_VAL ,
+.RB \- HUGE_VALF ,
+or
+.RB \- HUGE_VALL ,
+respectively.
+.P
+If
+.I x
+is less than \-1 (including negative infinity),
+a domain error occurs,
+and a NaN (not a number) is returned.
+.\" POSIX.1 specifies a possible range error if x is subnormal
+.\" glibc 2.8 doesn't do this
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is less than \-1
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Pole error: \fIx\fP is \-1
+.I errno
+is set to
+.B ERANGE
+(but see BUGS).
+A divide-by-zero floating-point exception
+.RB ( FE_DIVBYZERO )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR log1p (),
+.BR log1pf (),
+.BR log1pl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.\" BSD
+.SH BUGS
+Before glibc 2.22, the glibc implementation did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6792
+.I errno
+to
+.B EDOM
+when a domain error occurred.
+.P
+Before glibc 2.22, the glibc implementation did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6792
+.I errno
+to
+.B ERANGE
+when a range error occurred.
+.SH SEE ALSO
+.BR exp (3),
+.BR expm1 (3),
+.BR log (3)
diff --git a/man/man3/log1pf.3 b/man/man3/log1pf.3
new file mode 100644
index 000000000..a4dec80e7
--- /dev/null
+++ b/man/man3/log1pf.3
@@ -0,0 +1 @@
+.so man3/log1p.3
diff --git a/man/man3/log1pl.3 b/man/man3/log1pl.3
new file mode 100644
index 000000000..a4dec80e7
--- /dev/null
+++ b/man/man3/log1pl.3
@@ -0,0 +1 @@
+.so man3/log1p.3
diff --git a/man/man3/log2.3 b/man/man3/log2.3
new file mode 100644
index 000000000..11d8c3cc2
--- /dev/null
+++ b/man/man3/log2.3
@@ -0,0 +1,93 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH log2 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+log2, log2f, log2l \- base-2 logarithmic function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double log2(double " x );
+.BI "float log2f(float " x );
+.BI "long double log2l(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR log2 (),
+.BR log2f (),
+.BR log2l ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions return the base-2 logarithm of
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the base-2 logarithm of
+.IR x .
+.P
+For special cases, including where
+.I x
+is 0, 1, negative, infinity, or NaN, see
+.BR log (3).
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+For a discussion of the errors that can occur for these functions, see
+.BR log (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR log2 (),
+.BR log2f (),
+.BR log2l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR cbrt (3),
+.BR clog2 (3),
+.BR log (3),
+.BR log10 (3),
+.BR sqrt (3)
diff --git a/man/man3/log2f.3 b/man/man3/log2f.3
new file mode 100644
index 000000000..23aeb4ad0
--- /dev/null
+++ b/man/man3/log2f.3
@@ -0,0 +1 @@
+.so man3/log2.3
diff --git a/man/man3/log2l.3 b/man/man3/log2l.3
new file mode 100644
index 000000000..23aeb4ad0
--- /dev/null
+++ b/man/man3/log2l.3
@@ -0,0 +1 @@
+.so man3/log2.3
diff --git a/man/man3/logb.3 b/man/man3/logb.3
new file mode 100644
index 000000000..6d1cb5be8
--- /dev/null
+++ b/man/man3/logb.3
@@ -0,0 +1,142 @@
+'\" t
+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Inspired by a page by Walter Harms created 2002-08-10
+.\"
+.TH logb 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+logb, logbf, logbl \- get exponent of a floating-point value
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double logb(double " x );
+.BI "float logbf(float " x );
+.BI "long double logbl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR logb ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR logbf (),
+.BR logbl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions extract the exponent from the
+internal floating-point representation of
+.I x
+and return it as a floating-point value.
+The integer constant
+.BR FLT_RADIX ,
+defined in
+.IR <float.h> ,
+indicates the radix used for the system's floating-point representation.
+If
+.B FLT_RADIX
+is 2,
+.BI logb( x )
+is similar to
+.BI floor(log2(fabs( x )))\f[R],\f[]
+except that the latter may give an incorrect integer
+due to intermediate rounding.
+.P
+If
+.I x
+is subnormal,
+.BR logb ()
+returns the exponent
+.I x
+would have if it were normalized.
+.SH RETURN VALUE
+On success, these functions return the exponent of
+.IR x .
+.P
+If
+.I x
+is a NaN,
+a NaN is returned.
+.P
+If
+.I x
+is zero, then a pole error occurs, and the functions return
+.RB \- HUGE_VAL ,
+.RB \- HUGE_VALF ,
+or
+.RB \- HUGE_VALL ,
+respectively.
+.P
+If
+.I x
+is negative infinity or positive infinity, then
+positive infinity is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Pole error: \fIx\fP is 0
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+A divide-by-zero floating-point exception
+.RB ( FE_DIVBYZERO )
+is raised.
+.P
+These functions do not set
+.IR errno .
+.\" FIXME . Is it intentional that these functions do not set errno?
+.\" log(), log2(), log10() do set errno
+.\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6793
+.\"
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR logb (),
+.BR logbf (),
+.BR logbl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.TP
+.BR logb ()
+4.3BSD
+(see IEEE.3 in the 4.3BSD manual).
+.SH SEE ALSO
+.BR ilogb (3),
+.BR log (3)
diff --git a/man/man3/logbf.3 b/man/man3/logbf.3
new file mode 100644
index 000000000..4a70936a4
--- /dev/null
+++ b/man/man3/logbf.3
@@ -0,0 +1 @@
+.so man3/logb.3
diff --git a/man/man3/logbl.3 b/man/man3/logbl.3
new file mode 100644
index 000000000..4a70936a4
--- /dev/null
+++ b/man/man3/logbl.3
@@ -0,0 +1 @@
+.so man3/logb.3
diff --git a/man/man3/logf.3 b/man/man3/logf.3
new file mode 100644
index 000000000..7807e7642
--- /dev/null
+++ b/man/man3/logf.3
@@ -0,0 +1 @@
+.so man3/log.3
diff --git a/man/man3/login.3 b/man/man3/login.3
new file mode 100644
index 000000000..5190dbf4b
--- /dev/null
+++ b/man/man3/login.3
@@ -0,0 +1,151 @@
+'\" t
+.\" Derived from text written by Martin Schulze (or taken from glibc.info)
+.\" and text written by Paul Thompson - both copyright 2002.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH login 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+login, logout \- write utmp and wtmp entries
+.SH LIBRARY
+System utilities library
+.RI ( libutil ", " \-lutil )
+.SH SYNOPSIS
+.nf
+.B #include <utmp.h>
+.P
+.BI "void login(const struct utmp *" ut );
+.BI "int logout(const char *" ut_line );
+.fi
+.SH DESCRIPTION
+The utmp file records who is currently using the system.
+The wtmp file records all logins and logouts.
+See
+.BR utmp (5).
+.P
+The function
+.BR login ()
+takes the supplied
+.IR "struct utmp" ,
+.IR ut ,
+and writes it to both the utmp and the wtmp file.
+.P
+The function
+.BR logout ()
+clears the entry in the utmp file again.
+.SS GNU details
+More precisely,
+.BR login ()
+takes the argument
+.I ut
+struct, fills the field
+.I ut\->ut_type
+(if there is such a field) with the value
+.BR USER_PROCESS ,
+and fills the field
+.I ut\->ut_pid
+(if there is such a field) with the process ID of the calling process.
+Then it tries to fill the field
+.IR ut\->ut_line .
+It takes the first of
+.IR stdin ,
+.IR stdout ,
+.I stderr
+that is a terminal, and
+stores the corresponding pathname minus a possible leading
+.I /dev/
+into this field, and then writes the struct to the utmp file.
+On the other hand,
+if no terminal name was found, this field is filled with "???"
+and the struct is not written to the utmp file.
+After this, the struct is written to the wtmp file.
+.P
+The
+.BR logout ()
+function searches the utmp file for an entry matching the
+.I ut_line
+argument.
+If a record is found, it is updated by zeroing out the
+.I ut_name
+and
+.I ut_host
+fields, updating the
+.I ut_tv
+timestamp field and setting
+.I ut_type
+(if there is such a field) to
+.BR DEAD_PROCESS .
+.SH RETURN VALUE
+The
+.BR logout ()
+function returns 1 if the entry was successfully written to the
+database, or 0 if an error occurred.
+.SH FILES
+.TP
+.I /var/run/utmp
+user accounting database, configured through
+.B _PATH_UTMP
+in
+.I <paths.h>
+.TP
+.I /var/log/wtmp
+user accounting log file, configured through
+.B _PATH_WTMP
+in
+.I <paths.h>
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR login (),
+.BR logout ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:utent
+sig:ALRM timer
+T}
+.TE
+.P
+In the above table,
+.I utent
+in
+.I race:utent
+signifies that if any of the functions
+.BR setutent (3),
+.BR getutent (3),
+or
+.BR endutent (3)
+are used in parallel in different threads of a program,
+then data races could occur.
+.BR login ()
+and
+.BR logout ()
+calls those functions,
+so we use race:utent to remind users.
+.SH VERSIONS
+The member
+.I ut_user
+of
+.I struct utmp
+is called
+.I ut_name
+in BSD.
+Therefore,
+.I ut_name
+is defined as an alias for
+.I ut_user
+in
+.IR <utmp.h> .
+.SH STANDARDS
+BSD.
+.SH SEE ALSO
+.BR getutent (3),
+.BR utmp (5)
diff --git a/man/man3/login_tty.3 b/man/man3/login_tty.3
new file mode 100644
index 000000000..fb4952d52
--- /dev/null
+++ b/man/man3/login_tty.3
@@ -0,0 +1 @@
+.so man3/openpty.3
diff --git a/man/man3/logl.3 b/man/man3/logl.3
new file mode 100644
index 000000000..7807e7642
--- /dev/null
+++ b/man/man3/logl.3
@@ -0,0 +1 @@
+.so man3/log.3
diff --git a/man/man3/logout.3 b/man/man3/logout.3
new file mode 100644
index 000000000..a1ee67257
--- /dev/null
+++ b/man/man3/logout.3
@@ -0,0 +1 @@
+.so man3/login.3
diff --git a/man/man3/logwtmp.3 b/man/man3/logwtmp.3
new file mode 100644
index 000000000..0dc4dea39
--- /dev/null
+++ b/man/man3/logwtmp.3
@@ -0,0 +1 @@
+.so man3/updwtmp.3
diff --git a/man/man3/longjmp.3 b/man/man3/longjmp.3
new file mode 100644
index 000000000..7cf497fc3
--- /dev/null
+++ b/man/man3/longjmp.3
@@ -0,0 +1 @@
+.so man3/setjmp.3
diff --git a/man/man3/lrand48.3 b/man/man3/lrand48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/lrand48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/lrand48_r.3 b/man/man3/lrand48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/lrand48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/lrint.3 b/man/man3/lrint.3
new file mode 100644
index 000000000..74b91af9c
--- /dev/null
+++ b/man/man3/lrint.3
@@ -0,0 +1,110 @@
+'\" t
+.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH lrint 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lrint, lrintf, lrintl, llrint, llrintf, llrintl \- round to nearest integer
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "long lrint(double " x );
+.BI "long lrintf(float " x );
+.BI "long lrintl(long double " x );
+.P
+.BI "long long llrint(double " x );
+.BI "long long llrintf(float " x );
+.BI "long long llrintl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions round their argument to the nearest integer value,
+using the current rounding direction (see
+.BR fesetround (3)).
+.P
+Note that unlike the
+.BR rint (3)
+family of functions,
+the return type of these functions differs from
+that of their arguments.
+.SH RETURN VALUE
+These functions return the rounded integer value.
+.P
+If
+.I x
+is a NaN or an infinity,
+or the rounded value is too large to be stored in a
+.I long
+.RI ( "long long"
+in the case of the
+.B ll*
+functions),
+then a domain error occurs, and the return value is unspecified.
+.\" The return value is -(LONG_MAX - 1) or -(LLONG_MAX -1)
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is a NaN or infinite, or the rounded value is too large
+.\" .I errno
+.\" is set to
+.\" .BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.P
+These functions do not set
+.IR errno .
+.\" FIXME . Is it intentional that these functions do not set errno?
+.\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6798
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR lrint (),
+.BR lrintf (),
+.BR lrintl (),
+.BR llrint (),
+.BR llrintf (),
+.BR llrintl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR ceil (3),
+.BR floor (3),
+.BR lround (3),
+.BR nearbyint (3),
+.BR rint (3),
+.BR round (3)
diff --git a/man/man3/lrintf.3 b/man/man3/lrintf.3
new file mode 100644
index 000000000..d1c0af3b8
--- /dev/null
+++ b/man/man3/lrintf.3
@@ -0,0 +1 @@
+.so man3/lrint.3
diff --git a/man/man3/lrintl.3 b/man/man3/lrintl.3
new file mode 100644
index 000000000..d1c0af3b8
--- /dev/null
+++ b/man/man3/lrintl.3
@@ -0,0 +1 @@
+.so man3/lrint.3
diff --git a/man/man3/lround.3 b/man/man3/lround.3
new file mode 100644
index 000000000..b16854b2d
--- /dev/null
+++ b/man/man3/lround.3
@@ -0,0 +1,113 @@
+'\" t
+.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH lround 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lround, lroundf, lroundl, llround, llroundf, llroundl \- round to
+nearest integer
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "long lround(double " x );
+.BI "long lroundf(float " x );
+.BI "long lroundl(long double " x );
+.P
+.BI "long long llround(double " x );
+.BI "long long llroundf(float " x );
+.BI "long long llroundl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions round their argument to the nearest integer value,
+rounding halfway cases away from zero,
+regardless of the current rounding direction (see
+.BR fenv (3)).
+.P
+Note that unlike the
+.BR round (3)
+and
+.BR ceil (3),
+functions, the return type of these functions differs from
+that of their arguments.
+.SH RETURN VALUE
+These functions return the rounded integer value.
+.P
+If
+.I x
+is a NaN or an infinity,
+or the rounded value is too large to be stored in a
+.I long
+.RI ( "long long"
+in the case of the
+.B ll*
+functions),
+then a domain error occurs, and the return value is unspecified.
+.\" The return value is -(LONG_MAX - 1) or -(LLONG_MAX -1)
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is a NaN or infinite, or the rounded value is too large
+.\" .I errno
+.\" is set to
+.\" .BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.P
+These functions do not set
+.IR errno .
+.\" FIXME . Is it intentional that these functions do not set errno?
+.\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6797
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR lround (),
+.BR lroundf (),
+.BR lroundl (),
+.BR llround (),
+.BR llroundf (),
+.BR llroundl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR ceil (3),
+.BR floor (3),
+.BR lrint (3),
+.BR nearbyint (3),
+.BR rint (3),
+.BR round (3)
diff --git a/man/man3/lroundf.3 b/man/man3/lroundf.3
new file mode 100644
index 000000000..bcc9b0fda
--- /dev/null
+++ b/man/man3/lroundf.3
@@ -0,0 +1 @@
+.so man3/lround.3
diff --git a/man/man3/lroundl.3 b/man/man3/lroundl.3
new file mode 100644
index 000000000..bcc9b0fda
--- /dev/null
+++ b/man/man3/lroundl.3
@@ -0,0 +1 @@
+.so man3/lround.3
diff --git a/man/man3/lsearch.3 b/man/man3/lsearch.3
new file mode 100644
index 000000000..13871e9cf
--- /dev/null
+++ b/man/man3/lsearch.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright 1995 Jim Van Zandt <jrv@vanzandt.mv.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Corrected prototype and include, aeb, 990927
+.TH lsearch 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lfind, lsearch \- linear search of an array
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <search.h>
+.P
+.BI "void *lfind(const void " key [. size "], \
+const void " base [. size " * ." nmemb ],
+.BI "            size_t *" nmemb ", size_t " size ,
+.BI "            int(*" compar ")(const void [." size "], \
+const void [." size ]));
+.BI "void *lsearch(const void " key [. size "], \
+void " base [. size " * ." nmemb ],
+.BI "            size_t *" nmemb ", size_t " size ,
+.BI "            int(*" compar ")(const void [." size "], \
+const void [." size ]));
+.fi
+.SH DESCRIPTION
+.BR lfind ()
+and
+.BR lsearch ()
+perform a linear search for
+.I key
+in the array
+.I base
+which has
+.I *nmemb
+elements of
+.I size
+bytes each.
+The comparison function referenced by
+.I compar
+is expected to have two arguments which point to the
+.I key
+object and to an array member, in that order, and which
+returns zero if the
+.I key
+object matches the array member, and
+nonzero otherwise.
+.P
+If
+.BR lsearch ()
+does not find a matching element, then the
+.I key
+object is inserted at the end of the table, and
+.I *nmemb
+is
+incremented.
+In particular, one should know that a matching element
+exists, or that more room is available.
+.SH RETURN VALUE
+.BR lfind ()
+returns a pointer to a matching member of the array, or
+NULL if no match is found.
+.BR lsearch ()
+returns a pointer to
+a matching member of the array, or to the newly added member if no
+match is found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR lfind (),
+.BR lsearch ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+libc-4.6.27.
+.SH BUGS
+The naming is unfortunate.
+.SH SEE ALSO
+.BR bsearch (3),
+.BR hsearch (3),
+.BR tsearch (3)
diff --git a/man/man3/lseek64.3 b/man/man3/lseek64.3
new file mode 100644
index 000000000..e62a7238e
--- /dev/null
+++ b/man/man3/lseek64.3
@@ -0,0 +1,206 @@
+'\" t
+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright (c) 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH lseek64 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lseek64 \- reposition 64-bit read/write file offset
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _LARGEFILE64_SOURCE" "     /* See feature_test_macros(7) */"
+.B #include <sys/types.h>
+.B #include <unistd.h>
+.P
+.BI "off64_t lseek64(int " fd ", off64_t " offset ", int " whence );
+.fi
+.SH DESCRIPTION
+The
+.BR lseek ()
+family of functions reposition the offset of the open file associated
+with the file descriptor
+.I fd
+to
+.I offset
+bytes relative to the start, current position, or end of the file,
+when
+.I whence
+has the value
+.BR SEEK_SET ,
+.BR SEEK_CUR ,
+or
+.BR SEEK_END ,
+respectively.
+.P
+For more details, return value, and errors, see
+.BR lseek (2).
+.P
+Four interfaces are available:
+.BR lseek (),
+.BR lseek64 (),
+.BR llseek (),
+and
+.BR _llseek ().
+.\"
+.\" For some background details, see:
+.\" https://lore.kernel.org/linux-man/CAKgNAkhNSWR3uYhYYaxx74fZfJ3JrpfAAPVrK0AFk_cAOUsbDg@mail.gmail.com/
+.\"
+.SS lseek()
+Prototype:
+.P
+.in +4n
+.EX
+.BI "off_t lseek(int " fd ", off_t " offset ", int " whence );
+.EE
+.in
+.P
+The C library's
+.BR lseek ()
+wrapper function uses the type
+.IR off_t .
+This is a 32-bit signed type on 32-bit architectures, unless one
+compiles with
+.P
+.in +4n
+.EX
+#define _FILE_OFFSET_BITS 64
+.EE
+.in
+.P
+in which case it is a 64-bit signed type.
+.SS lseek64()
+Prototype:
+.P
+.in +4n
+.EX
+.BI "off64_t lseek64(int " fd ", off64_t " offset ", int " whence );
+.EE
+.in
+.P
+The
+.BR lseek64 ()
+library function uses a 64-bit type even when
+.I off_t
+is a 32-bit type.
+Its prototype (and the type
+.IR off64_t )
+is available only when one compiles with
+.P
+.in +4n
+.EX
+#define _LARGEFILE64_SOURCE
+.EE
+.in
+.P
+The function
+.BR lseek64 ()
+.\" in glibc 2.0.94, not in glibc 2.0.6
+is available since glibc 2.1.
+.\"
+.SS llseek()
+Prototype:
+.P
+.in +4n
+.EX
+.BI "loff_t llseek(int " fd ", loff_t " offset ", int " whence );
+.EE
+.in
+.P
+The type
+.I loff_t
+is a 64-bit signed type.
+The
+.BR llseek ()
+library function is available in glibc and works without special defines.
+However, the glibc headers do not provide a prototype.
+Users should add
+the above prototype, or something equivalent, to their own source.
+When users complained about data loss caused by a miscompilation of
+.BR e2fsck (8),
+glibc 2.1.3 added the link-time warning
+.P
+.in +4n
+"the \`llseek\' function may be dangerous; use \`lseek64\' instead."
+.in
+.P
+This makes this function unusable if one desires a warning-free
+compilation.
+.P
+Since glibc 2.28,
+.\" glibc commit 5c5c0dd747070db624c8e2c43691cec854f114ef
+this function symbol is no longer available to newly linked applications.
+.\"
+.SS _llseek()
+On 32-bit architectures,
+this is the system call that is used (by the C library wrapper functions)
+to implement all of the above functions.
+The prototype is:
+.P
+.in +4n
+.EX
+.BI "int _llseek(int " fd ", off_t " offset_hi ", off_t " offset_lo ,
+.BI "            loff_t *" result ", int " whence );
+.EE
+.in
+.P
+For more details, see
+.BR llseek (2).
+.P
+64-bit systems don't need an
+.BR _llseek ()
+system call.
+Instead, they have an
+.BR lseek (2)
+system call that supports 64-bit file offsets.
+.\" In arch/x86/entry/syscalls/syscall_32.tbl,
+.\" we see the following line:
+.\"
+.\"    140     i386    _llseek                 sys_llseek
+.\"
+.\" This is essentially telling us that 'sys_llseek' (the name generated
+.\" by SYSCALL_DEFINE5(llseek...)) is exposed to user-space as system call
+.\" number 140, and that system call number will (IIUC) be exposed in
+.\" autogenerated headers with the name "__NR__llseek" (i.e., "_llseek").
+.\" The "i386" is telling us that this happens in i386 (32-bit Intel).
+.\" There is nothing equivalent on x86-64, because 64 bit systems don't
+.\" need an _llseek system call.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR lseek64 ()
+T}	Thread safety	MT-Safe
+.TE
+.SH NOTES
+.BR lseek64 ()
+is one of the functions that was specified in the Large File Summit (LFS)
+specification that was completed in 1996.
+The purpose of the specification was to provide transitional support
+that allowed applications on 32-bit systems to access
+files whose size exceeds that which can be represented with a 32-bit
+.I off_t
+type.
+As noted above, this symbol is exposed by header files if the
+.B _LARGEFILE64_SOURCE
+feature test macro is defined.
+ALternatively, on a 32-bit system, the symbol
+.I lseek
+is aliased to
+.I lseek64
+if the macro
+.B _FILE_OFFSET_BITS
+is defined with the value 64.
+.SH SEE ALSO
+.BR llseek (2),
+.BR lseek (2)
diff --git a/man/man3/lutimes.3 b/man/man3/lutimes.3
new file mode 100644
index 000000000..31459803f
--- /dev/null
+++ b/man/man3/lutimes.3
@@ -0,0 +1 @@
+.so man3/futimes.3
diff --git a/man/man3/major.3 b/man/man3/major.3
new file mode 100644
index 000000000..eabbdd013
--- /dev/null
+++ b/man/man3/major.3
@@ -0,0 +1 @@
+.so man3/makedev.3
diff --git a/man/man3/makecontext.3 b/man/man3/makecontext.3
new file mode 100644
index 000000000..4ee3cc2c4
--- /dev/null
+++ b/man/man3/makecontext.3
@@ -0,0 +1,236 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer (aeb@cwi.nl)
+.\" and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2006-08-02, mtk, Added example program
+.\"
+.TH makecontext 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+makecontext, swapcontext \- manipulate user context
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <ucontext.h>
+.P
+.BI "void makecontext(ucontext_t *" ucp ", void (*" func ")(), int " argc \
+", ...);"
+.BI "int swapcontext(ucontext_t *restrict " oucp ,
+.BI "                const ucontext_t *restrict " ucp );
+.fi
+.SH DESCRIPTION
+In a System V-like environment, one has the type
+.I ucontext_t
+(defined in
+.I <ucontext.h>
+and described in
+.BR getcontext (3))
+and the four functions
+.BR getcontext (3),
+.BR setcontext (3),
+.BR makecontext (),
+and
+.BR swapcontext ()
+that allow user-level context switching
+between multiple threads of control within a process.
+.P
+The
+.BR makecontext ()
+function modifies the context pointed to
+by \fIucp\fP (which was obtained from a call to
+.BR getcontext (3)).
+Before invoking
+.BR makecontext (),
+the caller must allocate a new stack
+for this context and assign its address to \fIucp\->uc_stack\fP,
+and define a successor context and
+assign its address to \fIucp\->uc_link\fP.
+.P
+When this context is later activated (using
+.BR setcontext (3)
+or
+.BR swapcontext ())
+the function \fIfunc\fP is called,
+and passed the series of integer
+.RI ( int )
+arguments that follow
+.IR argc ;
+the caller must specify the number of these arguments in
+.IR argc .
+When this function returns, the successor context is activated.
+If the successor context pointer is NULL, the thread exits.
+.P
+The
+.BR swapcontext ()
+function saves the current context in
+the structure pointed to by \fIoucp\fP, and then activates the
+context pointed to by \fIucp\fP.
+.SH RETURN VALUE
+When successful,
+.BR swapcontext ()
+does not return.
+(But we may return later, in case \fIoucp\fP is
+activated, in which case it looks like
+.BR swapcontext ()
+returns 0.)
+On error,
+.BR swapcontext ()
+returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient stack space left.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR makecontext ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe race:ucp
+T}
+T{
+.na
+.nh
+.BR swapcontext ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe race:oucp race:ucp
+T}
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.1.
+SUSv2, POSIX.1-2001.
+Removed in POSIX.1-2008,
+citing portability issues, and
+recommending that applications be rewritten to use POSIX threads instead.
+.SH NOTES
+The interpretation of \fIucp\->uc_stack\fP is just as in
+.BR sigaltstack (2),
+namely, this struct contains the start and length of a memory area
+to be used as the stack, regardless of the direction of growth of
+the stack.
+Thus, it is not necessary for the user program to
+worry about this direction.
+.P
+On architectures where
+.I int
+and pointer types are the same size
+(e.g., x86-32, where both types are 32 bits),
+you may be able to get away with passing pointers as arguments to
+.BR makecontext ()
+following
+.IR argc .
+However, doing this is not guaranteed to be portable,
+is undefined according to the standards,
+and won't work on architectures where pointers are larger than
+.IR int s.
+Nevertheless, starting with glibc 2.8, glibc makes some changes to
+.BR makecontext (),
+to permit this on some 64-bit architectures (e.g., x86-64).
+.SH EXAMPLES
+The example program below demonstrates the use of
+.BR getcontext (3),
+.BR makecontext (),
+and
+.BR swapcontext ().
+Running the program produces the following output:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+main: swapcontext(&uctx_main, &uctx_func2)
+func2: started
+func2: swapcontext(&uctx_func2, &uctx_func1)
+func1: started
+func1: swapcontext(&uctx_func1, &uctx_func2)
+func2: returning
+func1: returning
+main: exiting
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (makecontext.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <ucontext.h>
+\&
+static ucontext_t uctx_main, uctx_func1, uctx_func2;
+\&
+#define handle_error(msg) \e
+    do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static void
+func1(void)
+{
+    printf("%s: started\en", __func__);
+    printf("%s: swapcontext(&uctx_func1, &uctx_func2)\en", __func__);
+    if (swapcontext(&uctx_func1, &uctx_func2) == \-1)
+        handle_error("swapcontext");
+    printf("%s: returning\en", __func__);
+}
+\&
+static void
+func2(void)
+{
+    printf("%s: started\en", __func__);
+    printf("%s: swapcontext(&uctx_func2, &uctx_func1)\en", __func__);
+    if (swapcontext(&uctx_func2, &uctx_func1) == \-1)
+        handle_error("swapcontext");
+    printf("%s: returning\en", __func__);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    char func1_stack[16384];
+    char func2_stack[16384];
+\&
+    if (getcontext(&uctx_func1) == \-1)
+        handle_error("getcontext");
+    uctx_func1.uc_stack.ss_sp = func1_stack;
+    uctx_func1.uc_stack.ss_size = sizeof(func1_stack);
+    uctx_func1.uc_link = &uctx_main;
+    makecontext(&uctx_func1, func1, 0);
+\&
+    if (getcontext(&uctx_func2) == \-1)
+        handle_error("getcontext");
+    uctx_func2.uc_stack.ss_sp = func2_stack;
+    uctx_func2.uc_stack.ss_size = sizeof(func2_stack);
+    /* Successor context is f1(), unless argc > 1 */
+    uctx_func2.uc_link = (argc > 1) ? NULL : &uctx_func1;
+    makecontext(&uctx_func2, func2, 0);
+\&
+    printf("%s: swapcontext(&uctx_main, &uctx_func2)\en", __func__);
+    if (swapcontext(&uctx_main, &uctx_func2) == \-1)
+        handle_error("swapcontext");
+\&
+    printf("%s: exiting\en", __func__);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR sigaction (2),
+.BR sigaltstack (2),
+.BR sigprocmask (2),
+.BR getcontext (3),
+.BR sigsetjmp (3)
diff --git a/man/man3/makedev.3 b/man/man3/makedev.3
new file mode 100644
index 000000000..7fd748e5f
--- /dev/null
+++ b/man/man3/makedev.3
@@ -0,0 +1,92 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH makedev 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+makedev, major, minor \- manage a device number
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/sysmacros.h>
+.P
+.BI "dev_t makedev(unsigned int " maj ", unsigned int " min );
+.P
+.BI "unsigned int major(dev_t " dev );
+.BI "unsigned int minor(dev_t " dev );
+.fi
+.SH DESCRIPTION
+A device ID consists of two parts:
+a major ID, identifying the class of the device,
+and a minor ID, identifying a specific instance of a device in that class.
+A device ID is represented using the type
+.IR dev_t .
+.P
+Given major and minor device IDs,
+.BR makedev ()
+combines these to produce a device ID, returned as the function result.
+This device ID can be given to
+.BR mknod (2),
+for example.
+.P
+The
+.BR major ()
+and
+.BR minor ()
+functions perform the converse task: given a device ID,
+they return, respectively, the major and minor components.
+These macros can be useful to, for example,
+decompose the device IDs in the structure returned by
+.BR stat (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR makedev (),
+.BR major (),
+.BR minor ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The BSDs expose the definitions for these macros via
+.IR <sys/types.h> .
+.SH STANDARDS
+None.
+.SH HISTORY
+BSD, HP-UX, Solaris, AIX, Irix.
+.\" The header location is inconsistent:
+.\" Could be sys/mkdev.h, sys/sysmacros.h, or sys/types.h.
+.P
+These interfaces are defined as macros.
+Since glibc 2.3.3,
+they have been aliases for three GNU-specific functions:
+.BR gnu_dev_makedev (),
+.BR gnu_dev_major (),
+and
+.BR gnu_dev_minor ().
+The latter names are exported, but the traditional names are more portable.
+.P
+Depending on the version,
+glibc also exposes definitions for these macros from
+.I <sys/types.h>
+if suitable feature test macros are defined.
+However, this behavior was deprecated in glibc 2.25,
+.\" glibc commit dbab6577c6684c62bd2521c1c29dc25c3cac966f
+and since glibc 2.28,
+.\" glibc commit e16deca62e16f645213dffd4ecd1153c37765f17
+.I <sys/types.h>
+no longer provides these definitions.
+.SH SEE ALSO
+.BR mknod (2),
+.BR stat (2)
diff --git a/man/man3/mallinfo.3 b/man/man3/mallinfo.3
new file mode 100644
index 000000000..20ac7f896
--- /dev/null
+++ b/man/man3/mallinfo.3
@@ -0,0 +1,338 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mallinfo 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mallinfo, mallinfo2 \- obtain memory allocation information
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <malloc.h>
+.P
+.B struct mallinfo mallinfo(void);
+.B struct mallinfo2 mallinfo2(void);
+.fi
+.SH DESCRIPTION
+These functions return a copy of a structure containing information about
+memory allocations performed by
+.BR malloc (3)
+and related functions.
+The structure returned by each function contains the same fields.
+However, the older function,
+.BR mallinfo (),
+is deprecated since the type used for the fields is too small (see BUGS).
+.P
+Note that not all allocations are visible to these functions;
+see BUGS and consider using
+.BR malloc_info (3)
+instead.
+.P
+The
+.I mallinfo2
+structure returned by
+.BR mallinfo2 ()
+is defined as follows:
+.P
+.in +4n
+.EX
+struct mallinfo2 {
+    size_t arena;     /* Non\-mmapped space allocated (bytes) */
+    size_t ordblks;   /* Number of free chunks */
+    size_t smblks;    /* Number of free fastbin blocks */
+    size_t hblks;     /* Number of mmapped regions */
+    size_t hblkhd;    /* Space allocated in mmapped regions
+                         (bytes) */
+    size_t usmblks;   /* See below */
+    size_t fsmblks;   /* Space in freed fastbin blocks (bytes) */
+    size_t uordblks;  /* Total allocated space (bytes) */
+    size_t fordblks;  /* Total free space (bytes) */
+    size_t keepcost;  /* Top\-most, releasable space (bytes) */
+};
+.EE
+.in
+.P
+The
+.I mallinfo
+structure returned by the deprecated
+.BR mallinfo ()
+function is exactly the same, except that the fields are typed as
+.IR int .
+.P
+The structure fields contain the following information:
+.TP 10
+.I arena
+The total amount of memory allocated by means other than
+.BR mmap (2)
+(i.e., memory allocated on the heap).
+This figure includes both in-use blocks and blocks on the free list.
+.TP
+.I ordblks
+The number of ordinary (i.e., non-fastbin) free blocks.
+.TP
+.I smblks
+.\" the glibc info page wrongly says this field is unused
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=26746
+The number of fastbin free blocks (see
+.BR mallopt (3)).
+.TP
+.I hblks
+The number of blocks currently allocated using
+.BR mmap (2).
+(See the discussion of
+.B M_MMAP_THRESHOLD
+in
+.BR mallopt (3).)
+.TP
+.I hblkhd
+The number of bytes in blocks currently allocated using
+.BR mmap (2).
+.TP
+.I usmblks
+This field is unused, and is always 0.
+.\" It seems to have been zero since at least as far back as glibc 2.15
+Historically, it was the "highwater mark" for allocated space\[em]that is,
+the maximum amount of space that was ever allocated (in bytes);
+this field was maintained only in nonthreading environments.
+.TP
+.I fsmblks
+.\" the glibc info page wrongly says this field is unused
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=26746
+The total number of bytes in fastbin free blocks.
+.TP
+.I uordblks
+The total number of bytes used by in-use allocations.
+.TP
+.I fordblks
+The total number of bytes in free blocks.
+.TP
+.I keepcost
+The total amount of releasable free space at the top
+of the heap.
+This is the maximum number of bytes that could ideally
+(i.e., ignoring page alignment restrictions, and so on) be released by
+.BR malloc_trim (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mallinfo (),
+.BR mallinfo2 ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe init const:mallopt
+T}
+.TE
+.P
+.BR mallinfo ()/
+.BR mallinfo2 ()
+would access some global internal objects.
+If modify them with non-atomically,
+may get inconsistent results.
+The identifier
+.I mallopt
+in
+.I const:mallopt
+mean that
+.BR mallopt ()
+would modify the global internal objects with atomics, that make sure
+.BR mallinfo ()/
+.BR mallinfo2 ()
+is safe enough, others modify with non-atomically maybe not.
+.SH STANDARDS
+None.
+.SH HISTORY
+.TP
+.BR mallinfo ()
+glibc 2.0.
+SVID.
+.TP
+.BR mallinfo2 ()
+.\" commit e3960d1c57e57f33e0e846d615788f4ede73b945
+glibc 2.33.
+.SH BUGS
+.\" FIXME . http://sourceware.org/bugzilla/show_bug.cgi?id=208
+.\" See the 24 Aug 2011 mail by Paul Pluzhnikov:
+.\"     "[patch] Fix mallinfo() to accumulate results for all arenas"
+.\" on libc-alpha@sourceware.org
+.B Information is returned for only the main memory allocation area.
+Allocations in other arenas are excluded.
+See
+.BR malloc_stats (3)
+and
+.BR malloc_info (3)
+for alternatives that include information about other arenas.
+.P
+The fields of the
+.I mallinfo
+structure that is returned by the older
+.BR mallinfo ()
+function are typed as
+.IR int .
+However, because some internal bookkeeping values may be of type
+.IR long ,
+the reported values may wrap around zero and thus be inaccurate.
+.SH EXAMPLES
+The program below employs
+.BR mallinfo2 ()
+to retrieve memory allocation statistics before and after
+allocating and freeing some blocks of memory.
+The statistics are displayed on standard output.
+.P
+The first two command-line arguments specify the number and size of
+blocks to be allocated with
+.BR malloc (3).
+.P
+The remaining three arguments specify which of the allocated blocks
+should be freed with
+.BR free (3).
+These three arguments are optional, and specify (in order):
+the step size to be used in the loop that frees blocks
+(the default is 1, meaning free all blocks in the range);
+the ordinal position of the first block to be freed
+(default 0, meaning the first allocated block);
+and a number one greater than the ordinal position
+of the last block to be freed
+(default is one greater than the maximum block number).
+If these three arguments are omitted,
+then the defaults cause all allocated blocks to be freed.
+.P
+In the following example run of the program,
+1000 allocations of 100 bytes are performed,
+and then every second allocated block is freed:
+.P
+.in +4n
+.EX
+$ \fB./a.out 1000 100 2\fP
+============== Before allocating blocks ==============
+Total non\-mmapped bytes (arena):       0
+# of free chunks (ordblks):            1
+# of free fastbin blocks (smblks):     0
+# of mapped regions (hblks):           0
+Bytes in mapped regions (hblkhd):      0
+Max. total allocated space (usmblks):  0
+Free bytes held in fastbins (fsmblks): 0
+Total allocated space (uordblks):      0
+Total free space (fordblks):           0
+Topmost releasable block (keepcost):   0
+\&
+============== After allocating blocks ==============
+Total non\-mmapped bytes (arena):       135168
+# of free chunks (ordblks):            1
+# of free fastbin blocks (smblks):     0
+# of mapped regions (hblks):           0
+Bytes in mapped regions (hblkhd):      0
+Max. total allocated space (usmblks):  0
+Free bytes held in fastbins (fsmblks): 0
+Total allocated space (uordblks):      104000
+Total free space (fordblks):           31168
+Topmost releasable block (keepcost):   31168
+\&
+============== After freeing blocks ==============
+Total non\-mmapped bytes (arena):       135168
+# of free chunks (ordblks):            501
+# of free fastbin blocks (smblks):     0
+# of mapped regions (hblks):           0
+Bytes in mapped regions (hblkhd):      0
+Max. total allocated space (usmblks):  0
+Free bytes held in fastbins (fsmblks): 0
+Total allocated space (uordblks):      52000
+Total free space (fordblks):           83168
+Topmost releasable block (keepcost):   31168
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (mallinfo.c)
+.EX
+#include <malloc.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+static void
+display_mallinfo2(void)
+{
+    struct mallinfo2 mi;
+\&
+    mi = mallinfo2();
+\&
+    printf("Total non\-mmapped bytes (arena):       %zu\en", mi.arena);
+    printf("# of free chunks (ordblks):            %zu\en", mi.ordblks);
+    printf("# of free fastbin blocks (smblks):     %zu\en", mi.smblks);
+    printf("# of mapped regions (hblks):           %zu\en", mi.hblks);
+    printf("Bytes in mapped regions (hblkhd):      %zu\en", mi.hblkhd);
+    printf("Max. total allocated space (usmblks):  %zu\en", mi.usmblks);
+    printf("Free bytes held in fastbins (fsmblks): %zu\en", mi.fsmblks);
+    printf("Total allocated space (uordblks):      %zu\en", mi.uordblks);
+    printf("Total free space (fordblks):           %zu\en", mi.fordblks);
+    printf("Topmost releasable block (keepcost):   %zu\en", mi.keepcost);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+#define MAX_ALLOCS 2000000
+    char *alloc[MAX_ALLOCS];
+    size_t blockSize, numBlocks, freeBegin, freeEnd, freeStep;
+\&
+    if (argc < 3 || strcmp(argv[1], "\-\-help") == 0) {
+        fprintf(stderr, "%s num\-blocks block\-size [free\-step "
+                "[start\-free [end\-free]]]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    numBlocks = atoi(argv[1]);
+    blockSize = atoi(argv[2]);
+    freeStep = (argc > 3) ? atoi(argv[3]) : 1;
+    freeBegin = (argc > 4) ? atoi(argv[4]) : 0;
+    freeEnd = (argc > 5) ? atoi(argv[5]) : numBlocks;
+\&
+    printf("============== Before allocating blocks ==============\en");
+    display_mallinfo2();
+\&
+    for (size_t j = 0; j < numBlocks; j++) {
+        if (numBlocks >= MAX_ALLOCS) {
+            fprintf(stderr, "Too many allocations\en");
+            exit(EXIT_FAILURE);
+        }
+\&
+        alloc[j] = malloc(blockSize);
+        if (alloc[j] == NULL) {
+            perror("malloc");
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    printf("\en============== After allocating blocks ==============\en");
+    display_mallinfo2();
+\&
+    for (size_t j = freeBegin; j < freeEnd; j += freeStep)
+        free(alloc[j]);
+\&
+    printf("\en============== After freeing blocks ==============\en");
+    display_mallinfo2();
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR mmap (2),
+.BR malloc (3),
+.BR malloc_info (3),
+.BR malloc_stats (3),
+.BR malloc_trim (3),
+.BR mallopt (3)
diff --git a/man/man3/mallinfo2.3 b/man/man3/mallinfo2.3
new file mode 100644
index 000000000..25caee77b
--- /dev/null
+++ b/man/man3/mallinfo2.3
@@ -0,0 +1 @@
+.so man3/mallinfo.3
diff --git a/man/man3/malloc.3 b/man/man3/malloc.3
new file mode 100644
index 000000000..e164d588f
--- /dev/null
+++ b/man/man3/malloc.3
@@ -0,0 +1,460 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright 2007, 2012, 2018, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 19:00:59 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Clarification concerning realloc, iwj10@cus.cam.ac.uk (Ian Jackson), 950701
+.\" Documented MALLOC_CHECK_, Wolfram Gloger (wmglo@dent.med.uni-muenchen.de)
+.\" 2007-09-15 mtk: added notes on malloc()'s use of sbrk() and mmap().
+.\"
+.\" FIXME . Review http://austingroupbugs.net/view.php?id=374
+.\" to see what changes are required on this page.
+.\"
+.TH malloc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+malloc, free, calloc, realloc, reallocarray \- allocate and free dynamic memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "void *malloc(size_t " size );
+.BI "void free(void *_Nullable " ptr );
+.BI "void *calloc(size_t " nmemb ", size_t " size );
+.BI "void *realloc(void *_Nullable " ptr ", size_t "  size );
+.BI "void *reallocarray(void *_Nullable " ptr ", size_t " nmemb ", size_t " size );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR reallocarray ():
+.nf
+    Since glibc 2.29:
+        _DEFAULT_SOURCE
+    glibc 2.28 and earlier:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.SS malloc()
+The
+.BR malloc ()
+function allocates
+.I size
+bytes and returns a pointer to the allocated memory.
+.IR "The memory is not initialized" .
+If
+.I size
+is 0, then
+.BR malloc ()
+returns a unique pointer value that can later be successfully passed to
+.BR free ().
+(See "Nonportable behavior" for portability issues.)
+.SS free()
+The
+.BR free ()
+function frees the memory space pointed to by
+.IR ptr ,
+which must have been returned by a previous call to
+.BR malloc ()
+or related functions.
+Otherwise, or if
+.I ptr
+has already been freed, undefined behavior occurs.
+If
+.I ptr
+is NULL, no operation is performed.
+.SS calloc()
+The
+.BR calloc ()
+function allocates memory for an array of
+.I nmemb
+elements of
+.I size
+bytes each and returns a pointer to the allocated memory.
+The memory is set to zero.
+If
+.I nmemb
+or
+.I size
+is 0, then
+.BR calloc ()
+returns a unique pointer value that can later be successfully passed to
+.BR free ().
+.P
+If the multiplication of
+.I nmemb
+and
+.I size
+would result in integer overflow, then
+.BR calloc ()
+returns an error.
+By contrast,
+an integer overflow would not be detected in the following call to
+.BR malloc (),
+with the result that an incorrectly sized block of memory would be allocated:
+.P
+.in +4n
+.EX
+malloc(nmemb * size);
+.EE
+.in
+.SS realloc()
+The
+.BR realloc ()
+function changes the size of the memory block pointed to by
+.I ptr
+to
+.I size
+bytes.
+The contents of the memory
+will be unchanged in the range from the start of the region
+up to the minimum of the old and new sizes.
+If the new size is larger than the old size, the added memory will
+.I not
+be initialized.
+.P
+If
+.I ptr
+is NULL, then the call is equivalent to
+.IR malloc(size) ,
+for all values of
+.IR size .
+.P
+If
+.I size
+is equal to zero,
+and
+.I ptr
+is not NULL, then the call is equivalent to
+.I free(ptr)
+(but see "Nonportable behavior" for portability issues).
+.P
+Unless
+.I ptr
+is NULL, it must have been returned by an earlier call to
+.B malloc
+or related functions.
+If the area pointed to was moved, a
+.I free(ptr)
+is done.
+.SS reallocarray()
+The
+.BR reallocarray ()
+function changes the size of (and possibly moves)
+the memory block pointed to by
+.I ptr
+to be large enough for an array of
+.I nmemb
+elements, each of which is
+.I size
+bytes.
+It is equivalent to the call
+.P
+.in +4n
+.EX
+realloc(ptr, nmemb * size);
+.EE
+.in
+.P
+However, unlike that
+.BR realloc ()
+call,
+.BR reallocarray ()
+fails safely in the case where the multiplication would overflow.
+If such an overflow occurs,
+.BR reallocarray ()
+returns an error.
+.SH RETURN VALUE
+The
+.BR malloc (),
+.BR calloc (),
+.BR realloc (),
+and
+.BR reallocarray ()
+functions return a pointer to the allocated memory,
+which is suitably aligned for any type that fits into
+the requested size or less.
+On error, these functions return NULL and set
+.IR errno .
+Attempting to allocate more than
+.B PTRDIFF_MAX
+bytes is considered an error, as an object that large
+could cause later pointer subtraction to overflow.
+.P
+The
+.BR free ()
+function returns no value, and preserves
+.IR errno .
+.P
+The
+.BR realloc ()
+and
+.BR reallocarray ()
+functions return NULL if
+.I ptr
+is not NULL and the requested size is zero;
+this is not considered an error.
+(See "Nonportable behavior" for portability issues.)
+Otherwise, the returned pointer may be the same as
+.I ptr
+if the allocation was not moved
+(e.g., there was room to expand the allocation in-place), or different from
+.I ptr
+if the allocation was moved to a new address.
+If these functions fail,
+the original block is left untouched; it is not freed or moved.
+.SH ERRORS
+.BR calloc (),
+.BR malloc (),
+.BR realloc (),
+and
+.BR reallocarray ()
+can fail with the following error:
+.TP
+.B ENOMEM
+Out of memory.
+Possibly, the application hit the
+.B RLIMIT_AS
+or
+.B RLIMIT_DATA
+limit described in
+.BR getrlimit (2).
+Another reason could be that
+the number of mappings created by the caller process
+exceeded the limit specified by
+.IR /proc/sys/vm/max_map_count .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR malloc (),
+.BR free (),
+.BR calloc (),
+.BR realloc ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR malloc ()
+.TQ
+.BR free ()
+.TQ
+.BR calloc ()
+.TQ
+.BR realloc ()
+C11, POSIX.1-2008.
+.TP
+.BR reallocarray ()
+None.
+.SH HISTORY
+.TP
+.BR malloc ()
+.TQ
+.BR free ()
+.TQ
+.BR calloc ()
+.TQ
+.BR realloc ()
+POSIX.1-2001, C89.
+.TP
+.BR reallocarray ()
+glibc 2.26.
+OpenBSD 5.6, FreeBSD 11.0.
+.P
+.BR malloc ()
+and related functions rejected sizes greater than
+.B PTRDIFF_MAX
+starting in glibc 2.30.
+.P
+.BR free ()
+preserved
+.I errno
+starting in glibc 2.33.
+.SH NOTES
+By default, Linux follows an optimistic memory allocation strategy.
+This means that when
+.BR malloc ()
+returns non-NULL there is no guarantee that the memory really
+is available.
+In case it turns out that the system is out of memory,
+one or more processes will be killed by the OOM killer.
+For more information, see the description of
+.I /proc/sys/vm/overcommit_memory
+and
+.I /proc/sys/vm/oom_adj
+in
+.BR proc (5),
+and the Linux kernel source file
+.IR Documentation/vm/overcommit\-accounting.rst .
+.P
+Normally,
+.BR malloc ()
+allocates memory from the heap, and adjusts the size of the heap
+as required, using
+.BR sbrk (2).
+When allocating blocks of memory larger than
+.B MMAP_THRESHOLD
+bytes, the glibc
+.BR malloc ()
+implementation allocates the memory as a private anonymous mapping using
+.BR mmap (2).
+.B MMAP_THRESHOLD
+is 128\ kB by default, but is adjustable using
+.BR mallopt (3).
+Prior to Linux 4.7
+allocations performed using
+.BR mmap (2)
+were unaffected by the
+.B RLIMIT_DATA
+resource limit;
+since Linux 4.7, this limit is also enforced for allocations performed using
+.BR mmap (2).
+.P
+To avoid corruption in multithreaded applications,
+mutexes are used internally to protect the memory-management
+data structures employed by these functions.
+In a multithreaded application in which threads simultaneously
+allocate and free memory,
+there could be contention for these mutexes.
+To scalably handle memory allocation in multithreaded applications,
+glibc creates additional
+.I memory allocation arenas
+if mutex contention is detected.
+Each arena is a large region of memory that is internally allocated
+by the system
+(using
+.BR brk (2)
+or
+.BR mmap (2)),
+and managed with its own mutexes.
+.P
+If your program uses a private memory allocator,
+it should do so by replacing
+.BR malloc (),
+.BR free (),
+.BR calloc (),
+and
+.BR realloc ().
+The replacement functions must implement the documented glibc behaviors,
+including
+.I errno
+handling, size-zero allocations, and overflow checking;
+otherwise, other library routines may crash or operate incorrectly.
+For example, if the replacement
+.IR free ()
+does not preserve
+.IR errno ,
+then seemingly unrelated library routines may
+fail without having a valid reason in
+.IR errno .
+Private memory allocators may also need to replace other glibc functions;
+see "Replacing malloc" in the glibc manual for details.
+.P
+Crashes in memory allocators
+are almost always related to heap corruption, such as overflowing
+an allocated chunk or freeing the same pointer twice.
+.P
+The
+.BR malloc ()
+implementation is tunable via environment variables; see
+.BR mallopt (3)
+for details.
+.SS Nonportable behavior
+The behavior of
+these functions when the requested size is zero
+is glibc specific;
+other implementations may return NULL without setting
+.IR errno ,
+and portable POSIX programs should tolerate such behavior.
+See
+.BR realloc (3p).
+.P
+POSIX requires memory allocators
+to set
+.I errno
+upon failure.
+However, the C standard does not require this, and applications
+portable to non-POSIX platforms should not assume this.
+.P
+Portable programs should not use private memory allocators,
+as POSIX and the C standard do not allow replacement of
+.BR malloc (),
+.BR free (),
+.BR calloc (),
+and
+.BR realloc ().
+.SH EXAMPLES
+.EX
+#include <err.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define MALLOCARRAY(n, type)  ((type *) my_mallocarray(n, sizeof(type)))
+#define MALLOC(type)          MALLOCARRAY(1, type)
+\&
+static inline void *my_mallocarray(size_t nmemb, size_t size);
+\&
+int
+main(void)
+{
+    char  *p;
+\&
+    p = MALLOCARRAY(32, char);
+    if (p == NULL)
+        err(EXIT_FAILURE, "malloc");
+\&
+    strlcpy(p, "foo", 32);
+    puts(p);
+}
+\&
+static inline void *
+my_mallocarray(size_t nmemb, size_t size)
+{
+    return reallocarray(NULL, nmemb, size);
+}
+.EE
+.SH SEE ALSO
+.\" http://g.oswego.edu/dl/html/malloc.html
+.\" A Memory Allocator - by Doug Lea
+.\"
+.\" http://www.bozemanpass.com/info/linux/malloc/Linux_Heap_Contention.html
+.\" Linux Heap, Contention in free() - David Boreham
+.\"
+.\" http://www.citi.umich.edu/projects/linux-scalability/reports/malloc.html
+.\" malloc() Performance in a Multithreaded Linux Environment -
+.\"     Check Lever, David Boreham
+.\"
+.ad l
+.nh
+.BR valgrind (1),
+.BR brk (2),
+.BR mmap (2),
+.BR alloca (3),
+.BR malloc_get_state (3),
+.BR malloc_info (3),
+.BR malloc_trim (3),
+.BR malloc_usable_size (3),
+.BR mallopt (3),
+.BR mcheck (3),
+.BR mtrace (3),
+.BR posix_memalign (3)
+.P
+For details of the GNU C library implementation, see
+.UR https://sourceware.org/glibc/wiki/MallocInternals
+.UE .
diff --git a/man/man3/malloc_get_state.3 b/man/man3/malloc_get_state.3
new file mode 100644
index 000000000..51783bc57
--- /dev/null
+++ b/man/man3/malloc_get_state.3
@@ -0,0 +1,115 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH malloc_get_state 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+malloc_get_state, malloc_set_state \-
+record and restore state of malloc implementation
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <malloc.h>
+.P
+.B void *malloc_get_state(void);
+.BI "int malloc_set_state(void *" state );
+.fi
+.SH DESCRIPTION
+.IR Note :
+these functions are removed in glibc 2.25.
+.P
+The
+.BR malloc_get_state ()
+function records the current state of all
+.BR malloc (3)
+internal bookkeeping variables
+(but not the actual contents of the heap
+or the state of
+.BR malloc_hook (3)
+functions pointers).
+The state is recorded in a system-dependent opaque data structure
+dynamically allocated via
+.BR malloc (3),
+and a pointer to that data structure is returned as the function result.
+(It is the caller's responsibility to
+.BR free (3)
+this memory.)
+.P
+The
+.BR malloc_set_state ()
+function restores the state of all
+.BR malloc (3)
+internal bookkeeping variables to the values recorded in
+the opaque data structure pointed to by
+.IR state .
+.SH RETURN VALUE
+On success,
+.BR malloc_get_state ()
+returns a pointer to a newly allocated opaque data structure.
+On error (for example, memory could not be allocated for the data structure),
+.BR malloc_get_state ()
+returns NULL.
+.P
+On success,
+.BR malloc_set_state ()
+returns 0.
+If the implementation detects that
+.I state
+does not point to a correctly formed data structure,
+.\" if(ms->magic != MALLOC_STATE_MAGIC) return -1;
+.BR malloc_set_state ()
+returns \-1.
+If the implementation detects that
+the version of the data structure referred to by
+.I state
+is a more recent version than this implementation knows about,
+.\" /* Must fail if the major version is too high. */
+.\" if((ms->version & ~0xffl) > (MALLOC_STATE_VERSION & ~0xffl)) return -2;
+.BR malloc_set_state ()
+returns \-2.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR malloc_get_state (),
+.BR malloc_set_state ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH NOTES
+These functions are useful when using this
+.BR malloc (3)
+implementation as part of a shared library,
+and the heap contents are saved/restored via some other method.
+This technique is used by GNU Emacs to implement its "dumping" function.
+.P
+Hook function pointers are never saved or restored by these
+functions, with two exceptions:
+if malloc checking (see
+.BR mallopt (3))
+was in use when
+.BR malloc_get_state ()
+was called, then
+.BR malloc_set_state ()
+resets malloc checking hooks
+.\" i.e., calls __malloc_check_init()
+if possible;
+.\" i.e., malloc checking is not already in use
+.\" and the caller requested malloc checking
+if malloc checking was not in use in the recorded state,
+but the caller has requested malloc checking,
+then the hooks are reset to 0.
+.SH SEE ALSO
+.BR malloc (3),
+.BR mallopt (3)
diff --git a/man/man3/malloc_hook.3 b/man/man3/malloc_hook.3
new file mode 100644
index 000000000..bddcdf3e2
--- /dev/null
+++ b/man/man3/malloc_hook.3
@@ -0,0 +1,154 @@
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Heavily based on glibc documentation
+.\" Polished, added docs, removed glibc doc bug, 2002-07-20, aeb
+.\"
+.TH __malloc_hook 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+__malloc_hook, __malloc_initialize_hook,
+__memalign_hook, __free_hook, __realloc_hook,
+__after_morecore_hook \- malloc debugging variables (DEPRECATED)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <malloc.h>"
+.P
+.BI "void *(*volatile __malloc_hook)(size_t " size ", const void *" caller );
+.P
+.BI "void *(*volatile __realloc_hook)(void *" ptr ", size_t " size ,
+.BI "                         const void *" caller );
+.P
+.BI "void *(*volatile __memalign_hook)(size_t " alignment ", size_t " size ,
+.BI "                         const void *" caller );
+.P
+.BI "void (*volatile __free_hook)(void *" ptr ", const void *" caller );
+.P
+.B "void (*__malloc_initialize_hook)(void);"
+.P
+.B "void (*volatile __after_morecore_hook)(void);"
+.fi
+.SH DESCRIPTION
+The GNU C library lets you modify the behavior of
+.BR malloc (3),
+.BR realloc (3),
+and
+.BR free (3)
+by specifying appropriate hook functions.
+You can use these hooks
+to help you debug programs that use dynamic memory allocation,
+for example.
+.P
+The variable
+.B __malloc_initialize_hook
+points at a function that is called once when the malloc implementation
+is initialized.
+This is a weak variable, so it can be overridden in
+the application with a definition like the following:
+.P
+.in +4n
+.EX
+void (*__malloc_initialize_hook)(void) = my_init_hook;
+.EE
+.in
+.P
+Now the function
+.IR my_init_hook ()
+can do the initialization of all hooks.
+.P
+The four functions pointed to by
+.BR __malloc_hook ,
+.BR __realloc_hook ,
+.BR __memalign_hook ,
+.B __free_hook
+have a prototype like the functions
+.BR malloc (3),
+.BR realloc (3),
+.BR memalign (3),
+.BR free (3),
+respectively, except that they have a final argument
+.I caller
+that gives the address of the caller of
+.BR malloc (3),
+etc.
+.P
+The variable
+.B __after_morecore_hook
+points at a function that is called each time after
+.BR sbrk (2)
+was asked for more memory.
+.SH STANDARDS
+GNU.
+.SH NOTES
+The use of these hook functions is not safe in multithreaded programs,
+and they are now deprecated.
+From glibc 2.24 onwards, the
+.B __malloc_initialize_hook
+variable has been removed from the API,
+and from glibc 2.34 onwards, all
+the hook variables have been removed from the API.
+.\" https://bugzilla.redhat.com/show_bug.cgi?id=450187
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=9957
+Programmers should instead preempt calls to the relevant functions
+by defining and exporting
+.BR malloc (),
+.BR free (),
+.BR realloc (),
+and
+.BR calloc ().
+.SH EXAMPLES
+Here is a short example of how to use these variables.
+.P
+.EX
+#include <stdio.h>
+#include <malloc.h>
+\&
+/* Prototypes for our hooks */
+static void my_init_hook(void);
+static void *my_malloc_hook(size_t, const void *);
+\&
+/* Variables to save original hooks */
+static void *(*old_malloc_hook)(size_t, const void *);
+\&
+/* Override initializing hook from the C library */
+void (*__malloc_initialize_hook)(void) = my_init_hook;
+\&
+static void
+my_init_hook(void)
+{
+    old_malloc_hook = __malloc_hook;
+    __malloc_hook = my_malloc_hook;
+}
+\&
+static void *
+my_malloc_hook(size_t size, const void *caller)
+{
+    void *result;
+\&
+    /* Restore all old hooks */
+    __malloc_hook = old_malloc_hook;
+\&
+    /* Call recursively */
+    result = malloc(size);
+\&
+    /* Save underlying hooks */
+    old_malloc_hook = __malloc_hook;
+\&
+    /* printf() might call malloc(), so protect it too */
+    printf("malloc(%zu) called from %p returns %p\en",
+            size, caller, result);
+\&
+    /* Restore our own hooks */
+    __malloc_hook = my_malloc_hook;
+\&
+    return result;
+}
+.EE
+.SH SEE ALSO
+.BR mallinfo (3),
+.BR malloc (3),
+.BR mcheck (3),
+.BR mtrace (3)
diff --git a/man/man3/malloc_info.3 b/man/man3/malloc_info.3
new file mode 100644
index 000000000..0aa55ba67
--- /dev/null
+++ b/man/man3/malloc_info.3
@@ -0,0 +1,257 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH malloc_info 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+malloc_info \- export malloc state to a stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <malloc.h>
+.P
+.BI "int malloc_info(int " options ", FILE *" stream );
+.fi
+.SH DESCRIPTION
+The
+.BR malloc_info ()
+function exports an XML string that describes the current state
+of the memory-allocation
+implementation in the caller.
+The string is printed on the file stream
+.IR stream .
+The exported string includes information about all arenas (see
+.BR malloc (3)).
+.P
+As currently implemented,
+.I options
+must be zero.
+.SH RETURN VALUE
+On success,
+.BR malloc_info ()
+returns 0.
+On failure, it returns \-1, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I options
+was nonzero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR malloc_info ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.10.
+.SH NOTES
+The memory-allocation information is provided as an XML string
+(rather than a C structure)
+because the information may change over time
+(according to changes in the underlying implementation).
+The output XML string includes a version field.
+.P
+The
+.BR open_memstream (3)
+function can be used to send the output of
+.BR malloc_info ()
+directly into a buffer in memory, rather than to a file.
+.P
+The
+.BR malloc_info ()
+function is designed to address deficiencies in
+.BR malloc_stats (3)
+and
+.BR mallinfo (3).
+.SH EXAMPLES
+The program below takes up to four command-line arguments,
+of which the first three are mandatory.
+The first argument specifies the number of threads that
+the program should create.
+All of the threads, including the main thread,
+allocate the number of blocks of memory specified by the second argument.
+The third argument controls the size of the blocks to be allocated.
+The main thread creates blocks of this size,
+the second thread created by the program allocates blocks of twice this size,
+the third thread allocates blocks of three times this size, and so on.
+.P
+The program calls
+.BR malloc_info ()
+twice to display the memory-allocation state.
+The first call takes place before any threads
+are created or memory allocated.
+The second call is performed after all threads have allocated memory.
+.P
+In the following example,
+the command-line arguments specify the creation of one additional thread,
+and both the main thread and the additional thread
+allocate 10000 blocks of memory.
+After the blocks of memory have been allocated,
+.BR malloc_info ()
+shows the state of two allocation arenas.
+.P
+.in +4n
+.EX
+.RB "$ " "getconf GNU_LIBC_VERSION"
+glibc 2.13
+.RB "$ " "./a.out 1 10000 100"
+============ Before allocating blocks ============
+<malloc version="1">
+<heap nr="0">
+<sizes>
+</sizes>
+<total type="fast" count="0" size="0"/>
+<total type="rest" count="0" size="0"/>
+<system type="current" size="135168"/>
+<system type="max" size="135168"/>
+<aspace type="total" size="135168"/>
+<aspace type="mprotect" size="135168"/>
+</heap>
+<total type="fast" count="0" size="0"/>
+<total type="rest" count="0" size="0"/>
+<system type="current" size="135168"/>
+<system type="max" size="135168"/>
+<aspace type="total" size="135168"/>
+<aspace type="mprotect" size="135168"/>
+</malloc>
+\&
+============ After allocating blocks ============
+<malloc version="1">
+<heap nr="0">
+<sizes>
+</sizes>
+<total type="fast" count="0" size="0"/>
+<total type="rest" count="0" size="0"/>
+<system type="current" size="1081344"/>
+<system type="max" size="1081344"/>
+<aspace type="total" size="1081344"/>
+<aspace type="mprotect" size="1081344"/>
+</heap>
+<heap nr="1">
+<sizes>
+</sizes>
+<total type="fast" count="0" size="0"/>
+<total type="rest" count="0" size="0"/>
+<system type="current" size="1032192"/>
+<system type="max" size="1032192"/>
+<aspace type="total" size="1032192"/>
+<aspace type="mprotect" size="1032192"/>
+</heap>
+<total type="fast" count="0" size="0"/>
+<total type="rest" count="0" size="0"/>
+<system type="current" size="2113536"/>
+<system type="max" size="2113536"/>
+<aspace type="total" size="2113536"/>
+<aspace type="mprotect" size="2113536"/>
+</malloc>
+.EE
+.in
+.SS Program source
+.\" SRC BEGIN (malloc_info.c)
+.EX
+#include <err.h>
+#include <errno.h>
+#include <malloc.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+static size_t        blockSize;
+static size_t        numThreads;
+static unsigned int  numBlocks;
+\&
+static void *
+thread_func(void *arg)
+{
+    int tn = (int) arg;
+\&
+    /* The multiplier \[aq](2 + tn)\[aq] ensures that each thread (including
+       the main thread) allocates a different amount of memory. */
+\&
+    for (unsigned int j = 0; j < numBlocks; j++)
+        if (malloc(blockSize * (2 + tn)) == NULL)
+            err(EXIT_FAILURE, "malloc\-thread");
+\&
+    sleep(100);         /* Sleep until main thread terminates. */
+    return NULL;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int        sleepTime;
+    pthread_t  *thr;
+\&
+    if (argc < 4) {
+        fprintf(stderr,
+                "%s num\-threads num\-blocks block\-size [sleep\-time]\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    numThreads = atoi(argv[1]);
+    numBlocks = atoi(argv[2]);
+    blockSize = atoi(argv[3]);
+    sleepTime = (argc > 4) ? atoi(argv[4]) : 0;
+\&
+    thr = calloc(numThreads, sizeof(*thr));
+    if (thr == NULL)
+        err(EXIT_FAILURE, "calloc");
+\&
+    printf("============ Before allocating blocks ============\en");
+    malloc_info(0, stdout);
+\&
+    /* Create threads that allocate different amounts of memory. */
+\&
+    for (size_t tn = 0; tn < numThreads; tn++) {
+        errno = pthread_create(&thr[tn], NULL, thread_func,
+                               (void *) tn);
+        if (errno != 0)
+            err(EXIT_FAILURE, "pthread_create");
+\&
+        /* If we add a sleep interval after the start\-up of each
+           thread, the threads likely won\[aq]t contend for malloc
+           mutexes, and therefore additional arenas won\[aq]t be
+           allocated (see malloc(3)). */
+\&
+        if (sleepTime > 0)
+            sleep(sleepTime);
+    }
+\&
+    /* The main thread also allocates some memory. */
+\&
+    for (unsigned int j = 0; j < numBlocks; j++)
+        if (malloc(blockSize) == NULL)
+            err(EXIT_FAILURE, "malloc");
+\&
+    sleep(2);           /* Give all threads a chance to
+                           complete allocations. */
+\&
+    printf("\en============ After allocating blocks ============\en");
+    malloc_info(0, stdout);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR mallinfo (3),
+.BR malloc (3),
+.BR malloc_stats (3),
+.BR mallopt (3),
+.BR open_memstream (3)
diff --git a/man/man3/malloc_set_state.3 b/man/man3/malloc_set_state.3
new file mode 100644
index 000000000..ff16dd792
--- /dev/null
+++ b/man/man3/malloc_set_state.3
@@ -0,0 +1 @@
+.so man3/malloc_get_state.3
diff --git a/man/man3/malloc_stats.3 b/man/man3/malloc_stats.3
new file mode 100644
index 000000000..cd515c069
--- /dev/null
+++ b/man/man3/malloc_stats.3
@@ -0,0 +1,65 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH malloc_stats 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+malloc_stats \- print memory allocation statistics
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <malloc.h>
+.P
+.B void malloc_stats(void);
+.fi
+.SH DESCRIPTION
+The
+.BR malloc_stats ()
+function prints (on standard error) statistics about memory allocated by
+.BR malloc (3)
+and related functions.
+For each arena (allocation area), this function prints
+the total amount of memory allocated
+and the total number of bytes consumed by in-use allocations.
+(These two values correspond to the
+.I arena
+and
+.I uordblks
+fields retrieved by
+.BR mallinfo (3).)
+In addition,
+the function prints the sum of these two statistics for all arenas,
+and the maximum number of blocks and bytes that were ever simultaneously
+allocated using
+.BR mmap (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR malloc_stats ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.0.
+.SH NOTES
+More detailed information about memory allocations in the main arena
+can be obtained using
+.BR mallinfo (3).
+.SH SEE ALSO
+.BR mmap (2),
+.BR mallinfo (3),
+.BR malloc (3),
+.BR malloc_info (3),
+.BR mallopt (3)
diff --git a/man/man3/malloc_trim.3 b/man/man3/malloc_trim.3
new file mode 100644
index 000000000..23677832b
--- /dev/null
+++ b/man/man3/malloc_trim.3
@@ -0,0 +1,81 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH malloc_trim 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+malloc_trim \- release free memory from the heap
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <malloc.h>
+.P
+.BI "int malloc_trim(size_t "  pad );
+.fi
+.SH DESCRIPTION
+The
+.BR malloc_trim ()
+function attempts to release free memory from the heap
+(by calling
+.BR sbrk (2)
+or
+.BR madvise (2)
+with suitable arguments).
+.P
+The
+.I pad
+argument specifies the amount of free space to leave untrimmed
+at the top of the heap.
+If this argument is 0, only the minimum amount of memory is maintained
+at the top of the heap (i.e., one page or less).
+A nonzero argument can be used to maintain some trailing space
+at the top of the heap in order to allow future allocations
+to be made without having to extend the heap with
+.BR sbrk (2).
+.SH RETURN VALUE
+The
+.BR malloc_trim ()
+function returns 1 if memory was actually released back to the system,
+or 0 if it was not possible to release any memory.
+.SH ERRORS
+No errors are defined.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR malloc_trim ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH VERSIONS
+glibc 2.0.
+.SH NOTES
+Only the main heap (using
+.BR sbrk (2))
+honors the
+.I pad
+argument; thread heaps do not.
+.P
+Since glibc 2.8 this function frees memory in all arenas and in all
+chunks with whole free pages.
+.\" See commit 68631c8eb92ff38d9da1ae34f6aa048539b199cc
+.\" (dated 2007-12-16) which adds iteration over all
+.\" arenas and frees all pages in chunks which are free.
+.P
+Before glibc 2.8 this function only freed memory at the
+top of the heap in the main arena.
+.SH SEE ALSO
+.BR sbrk (2),
+.BR malloc (3),
+.BR mallopt (3)
diff --git a/man/man3/malloc_usable_size.3 b/man/man3/malloc_usable_size.3
new file mode 100644
index 000000000..b2b6a73de
--- /dev/null
+++ b/man/man3/malloc_usable_size.3
@@ -0,0 +1,60 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH malloc_usable_size 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+malloc_usable_size \- obtain size of block of memory allocated from heap
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <malloc.h>
+.P
+.BI "size_t malloc_usable_size(void *_Nullable " ptr );
+.fi
+.SH DESCRIPTION
+This function can be used for
+diagnostics or statistics about allocations from
+.BR malloc (3)
+or a related function.
+.SH RETURN VALUE
+.BR malloc_usable_size ()
+returns a value no less than
+the size of the block of allocated memory pointed to by
+.IR ptr .
+If
+.I ptr
+is NULL, 0 is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR malloc_usable_size ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH CAVEATS
+The value returned by
+.BR malloc_usable_size ()
+may be greater than the requested size of the allocation
+because of various internal implementation details,
+none of which the programmer should rely on.
+This function is intended to only be used
+for diagnostics and statistics;
+writing to the excess memory without first calling
+.BR realloc (3)
+to resize the allocation is not supported.
+The returned value is only valid at the time of the call.
+.SH SEE ALSO
+.BR malloc (3)
diff --git a/man/man3/mallopt.3 b/man/man3/mallopt.3
new file mode 100644
index 000000000..822487251
--- /dev/null
+++ b/man/man3/mallopt.3
@@ -0,0 +1,619 @@
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mallopt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mallopt \- set memory allocation parameters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <malloc.h>
+.P
+.BI "int mallopt(int " param ", int " value );
+.fi
+.SH DESCRIPTION
+The
+.BR mallopt ()
+function adjusts parameters that control the behavior of the
+memory-allocation functions (see
+.BR malloc (3)).
+The
+.I param
+argument specifies the parameter to be modified, and
+.I value
+specifies the new value for that parameter.
+.P
+The following values can be specified for
+.IR param :
+.TP
+.B M_ARENA_MAX
+If this parameter has a nonzero value,
+it defines a hard limit on the maximum number of arenas that can be created.
+An arena represents a pool of memory that can be used by
+.BR malloc (3)
+(and similar) calls to service allocation requests.
+Arenas are thread safe and
+therefore may have multiple concurrent memory requests.
+The trade-off is between the number of threads and the number of arenas.
+The more arenas you have, the lower the per-thread contention,
+but the higher the memory usage.
+.IP
+The default value of this parameter is 0,
+meaning that the limit on the number of arenas is determined
+according to the setting of
+.BR M_ARENA_TEST .
+.IP
+This parameter has been available since glibc 2.10 via
+.BR \-\-enable\-experimental\-malloc ,
+and since glibc 2.15 by default.
+In some versions of the allocator there was no limit on the number
+of created arenas (e.g., CentOS 5, RHEL 5).
+.IP
+When employing newer glibc versions, applications may in
+some cases exhibit high contention when accessing arenas.
+In these cases, it may be beneficial to increase
+.B M_ARENA_MAX
+to match the number of threads.
+This is similar in behavior to strategies taken by tcmalloc and jemalloc
+(e.g., per-thread allocation pools).
+.TP
+.B M_ARENA_TEST
+This parameter specifies a value, in number of arenas created,
+at which point the system configuration will be examined
+to determine a hard limit on the number of created arenas.
+(See
+.B M_ARENA_MAX
+for the definition of an arena.)
+.IP
+The computation of the arena hard limit is implementation-defined
+and is usually calculated as a multiple of the number of available CPUs.
+Once the hard limit is computed, the result is final and constrains
+the total number of arenas.
+.IP
+The default value for the
+.B M_ARENA_TEST
+parameter is 2 on systems where
+.I sizeof(long)
+is 4; otherwise the default value is 8.
+.IP
+This parameter has been available since glibc 2.10 via
+.BR \-\-enable\-experimental\-malloc ,
+and since glibc 2.15 by default.
+.IP
+The value of
+.B M_ARENA_TEST
+is not used when
+.B M_ARENA_MAX
+has a nonzero value.
+.TP
+.B M_CHECK_ACTION
+Setting this parameter controls how glibc responds when various kinds
+of programming errors are detected (e.g., freeing the same pointer twice).
+The 3 least significant bits (2, 1, and 0) of the value assigned
+to this parameter determine the glibc behavior, as follows:
+.RS
+.TP
+Bit 0
+If this bit is set, then print a one-line message on
+.I stderr
+that provides details about the error.
+The message starts with the string "***\ glibc detected\ ***",
+followed by the program name,
+the name of the memory-allocation function in which the error was detected,
+a brief description of the error,
+and the memory address where the error was detected.
+.TP
+Bit 1
+If this bit is set, then,
+after printing any error message specified by bit 0,
+the program is terminated by calling
+.BR abort (3).
+Since glibc 2.4,
+if bit 0 is also set,
+then, between printing the error message and aborting,
+the program also prints a stack trace in the manner of
+.BR backtrace (3),
+and prints the process's memory mapping in the style of
+.IR /proc/ pid /maps
+(see
+.BR proc (5)).
+.TP
+Bit 2 (since glibc 2.4)
+This bit has an effect only if bit 0 is also set.
+If this bit is set,
+then the one-line message describing the error is simplified
+to contain just the name of the function where the error
+was detected and the brief description of the error.
+.RE
+.IP
+The remaining bits in
+.I value
+are ignored.
+.IP
+Combining the above details,
+the following numeric values are meaningful for
+.BR M_CHECK_ACTION :
+.RS 12
+.TP
+.B 0
+Ignore error conditions; continue execution (with undefined results).
+.TP
+.B 1
+Print a detailed error message and continue execution.
+.TP
+.B 2
+Abort the program.
+.TP
+.B 3
+Print detailed error message, stack trace, and memory mappings,
+and abort the program.
+.TP
+.B 5
+Print a simple error message and continue execution.
+.TP
+.B 7
+Print simple error message, stack trace, and memory mappings,
+and abort the program.
+.RE
+.IP
+Since glibc 2.3.4, the default value for the
+.B M_CHECK_ACTION
+parameter is 3.
+In glibc 2.3.3 and earlier, the default value is 1.
+.IP
+Using a nonzero
+.B M_CHECK_ACTION
+value can be useful because otherwise a crash may happen much later,
+and the true cause of the problem is then very hard to track down.
+.TP
+.B M_MMAP_MAX
+.\" The following text adapted from comments in the glibc source:
+This parameter specifies the maximum number of allocation requests that
+may be simultaneously serviced using
+.BR mmap (2).
+This parameter exists because some systems have a limited number
+of internal tables for use by
+.BR mmap (2),
+and using more than a few of them may degrade performance.
+.IP
+The default value is 65,536,
+a value which has no special significance and
+which serves only as a safeguard.
+Setting this parameter to 0 disables the use of
+.BR mmap (2)
+for servicing large allocation requests.
+.TP
+.B M_MMAP_THRESHOLD
+For allocations greater than or equal to the limit specified (in bytes) by
+.B M_MMAP_THRESHOLD
+that can't be satisfied from the free list,
+the memory-allocation functions employ
+.BR mmap (2)
+instead of increasing the program break using
+.BR sbrk (2).
+.IP
+Allocating memory using
+.BR mmap (2)
+has the significant advantage that the allocated memory blocks
+can always be independently released back to the system.
+(By contrast,
+the heap can be trimmed only if memory is freed at the top end.)
+On the other hand, there are some disadvantages to the use of
+.BR mmap (2):
+deallocated space is not placed on the free list
+for reuse by later allocations;
+memory may be wasted because
+.BR mmap (2)
+allocations must be page-aligned;
+and the kernel must perform the expensive task of zeroing out
+memory allocated via
+.BR mmap (2).
+Balancing these factors leads to a default setting of 128*1024 for the
+.B M_MMAP_THRESHOLD
+parameter.
+.IP
+The lower limit for this parameter is 0.
+The upper limit is
+.BR DEFAULT_MMAP_THRESHOLD_MAX :
+512*1024 on 32-bit systems or
+.I 4*1024*1024*sizeof(long)
+on 64-bit systems.
+.IP
+.IR Note :
+Nowadays, glibc uses a dynamic mmap threshold by default.
+The initial value of the threshold is 128*1024,
+but when blocks larger than the current threshold and less than or equal to
+.B DEFAULT_MMAP_THRESHOLD_MAX
+are freed,
+the threshold is adjusted upward to the size of the freed block.
+When dynamic mmap thresholding is in effect,
+the threshold for trimming the heap is also dynamically adjusted
+to be twice the dynamic mmap threshold.
+Dynamic adjustment of the mmap threshold is disabled if any of the
+.BR M_TRIM_THRESHOLD ,
+.BR M_TOP_PAD ,
+.BR M_MMAP_THRESHOLD ,
+or
+.B M_MMAP_MAX
+parameters is set.
+.TP
+.BR M_MXFAST " (since glibc 2.3)"
+.\" The following text adapted from comments in the glibc sources:
+Set the upper limit for memory allocation requests that are satisfied
+using "fastbins".
+(The measurement unit for this parameter is bytes.)
+Fastbins are storage areas that hold deallocated blocks of memory
+of the same size without merging adjacent free blocks.
+Subsequent reallocation of blocks of the same size can be handled
+very quickly by allocating from the fastbin,
+although memory fragmentation and the overall memory footprint
+of the program can increase.
+.IP
+The default value for this parameter is
+.I 64*sizeof(size_t)/4
+(i.e., 64 on 32-bit architectures).
+The range for this parameter is 0 to
+.IR 80*sizeof(size_t)/4 .
+Setting
+.B M_MXFAST
+to 0 disables the use of fastbins.
+.TP
+.BR M_PERTURB " (since glibc 2.4)"
+If this parameter is set to a nonzero value,
+then bytes of allocated memory (other than allocations via
+.BR calloc (3))
+are initialized to the complement of the value
+in the least significant byte of
+.IR value ,
+and when allocated memory is released using
+.BR free (3),
+the freed bytes are set to the least significant byte of
+.IR value .
+This can be useful for detecting errors where programs
+incorrectly rely on allocated memory being initialized to zero,
+or reuse values in memory that has already been freed.
+.IP
+The default value for this parameter is 0.
+.TP
+.B M_TOP_PAD
+This parameter defines the amount of padding to employ when calling
+.BR sbrk (2)
+to modify the program break.
+(The measurement unit for this parameter is bytes.)
+This parameter has an effect in the following circumstances:
+.RS
+.IP \[bu] 3
+When the program break is increased, then
+.B M_TOP_PAD
+bytes are added to the
+.BR sbrk (2)
+request.
+.IP \[bu]
+When the heap is trimmed as a consequence of calling
+.BR free (3)
+(see the discussion of
+.BR M_TRIM_THRESHOLD )
+this much free space is preserved at the top of the heap.
+.RE
+.IP
+In either case,
+the amount of padding is always rounded to a system page boundary.
+.IP
+Modifying
+.B M_TOP_PAD
+is a trade-off between increasing the number of system calls
+(when the parameter is set low)
+and wasting unused memory at the top of the heap
+(when the parameter is set high).
+.IP
+The default value for this parameter is 128*1024.
+.\" DEFAULT_TOP_PAD in glibc source
+.TP
+.B M_TRIM_THRESHOLD
+When the amount of contiguous free memory at the top of the heap
+grows sufficiently large,
+.BR free (3)
+employs
+.BR sbrk (2)
+to release this memory back to the system.
+(This can be useful in programs that continue to execute for
+a long period after freeing a significant amount of memory.)
+The
+.B M_TRIM_THRESHOLD
+parameter specifies the minimum size (in bytes) that
+this block of memory must reach before
+.BR sbrk (2)
+is used to trim the heap.
+.IP
+The default value for this parameter is 128*1024.
+Setting
+.B M_TRIM_THRESHOLD
+to \-1 disables trimming completely.
+.IP
+Modifying
+.B M_TRIM_THRESHOLD
+is a trade-off between increasing the number of system calls
+(when the parameter is set low)
+and wasting unused memory at the top of the heap
+(when the parameter is set high).
+.\"
+.SS Environment variables
+A number of environment variables can be defined
+to modify some of the same parameters as are controlled by
+.BR mallopt ().
+Using these variables has the advantage that the source code
+of the program need not be changed.
+To be effective, these variables must be defined before the
+first call to a memory-allocation function.
+(If the same parameters are adjusted via
+.BR mallopt (),
+then the
+.BR mallopt ()
+settings take precedence.)
+For security reasons,
+these variables are ignored in set-user-ID and set-group-ID programs.
+.P
+The environment variables are as follows
+(note the trailing underscore at the end of the name of some variables):
+.TP
+.B MALLOC_ARENA_MAX
+Controls the same parameter as
+.BR mallopt ()
+.BR M_ARENA_MAX .
+.TP
+.B MALLOC_ARENA_TEST
+Controls the same parameter as
+.BR mallopt ()
+.BR M_ARENA_TEST .
+.TP
+.B MALLOC_CHECK_
+This environment variable controls the same parameter as
+.BR mallopt ()
+.BR M_CHECK_ACTION .
+If this variable is set to a nonzero value,
+then a special implementation of the memory-allocation functions is used.
+(This is accomplished using the
+.BR malloc_hook (3)
+feature.)
+This implementation performs additional error checking,
+but is slower
+.\" On glibc 2.12/x86, a simple malloc()+free() loop is about 70% slower
+.\" when MALLOC_CHECK_ was set.
+than the standard set of memory-allocation functions.
+(This implementation does not detect all possible errors;
+memory leaks can still occur.)
+.IP
+The value assigned to this environment variable should be a single digit,
+whose meaning is as described for
+.BR M_CHECK_ACTION .
+Any characters beyond the initial digit are ignored.
+.IP
+For security reasons, the effect of
+.B MALLOC_CHECK_
+is disabled by default for set-user-ID and set-group-ID programs.
+However, if the file
+.I /etc/suid\-debug
+exists (the content of the file is irrelevant), then
+.B MALLOC_CHECK_
+also has an effect for set-user-ID and set-group-ID programs.
+.TP
+.B MALLOC_MMAP_MAX_
+Controls the same parameter as
+.BR mallopt ()
+.BR M_MMAP_MAX .
+.TP
+.B MALLOC_MMAP_THRESHOLD_
+Controls the same parameter as
+.BR mallopt ()
+.BR M_MMAP_THRESHOLD .
+.TP
+.B MALLOC_PERTURB_
+Controls the same parameter as
+.BR mallopt ()
+.BR M_PERTURB .
+.TP
+.B MALLOC_TRIM_THRESHOLD_
+Controls the same parameter as
+.BR mallopt ()
+.BR M_TRIM_THRESHOLD .
+.TP
+.B MALLOC_TOP_PAD_
+Controls the same parameter as
+.BR mallopt ()
+.BR M_TOP_PAD .
+.SH RETURN VALUE
+On success,
+.BR mallopt ()
+returns 1.
+On error, it returns 0.
+.SH ERRORS
+On error,
+.I errno
+is
+.I not
+set.
+.SH VERSIONS
+A similar function exists on many System V derivatives,
+but the range of values for
+.I param
+varies across systems.
+The SVID defined options
+.BR M_MXFAST ,
+.BR M_NLBLKS ,
+.BR M_GRAIN ,
+and
+.BR M_KEEP ,
+but only the first of these is implemented in glibc.
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.0.
+.SH BUGS
+Specifying an invalid value for
+.I param
+does not generate an error.
+.P
+A calculation error within the glibc implementation means that
+a call of the form:
+.\" FIXME . This looks buggy:
+.\" setting the M_MXFAST limit rounds up:    (s + SIZE_SZ) & ~MALLOC_ALIGN_MASK)
+.\" malloc requests are rounded up:
+.\"    (req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=12129
+.P
+.in +4n
+.EX
+mallopt(M_MXFAST, n)
+.EE
+.in
+.P
+does not result in fastbins being employed for all allocations of size up to
+.IR n .
+To ensure desired results,
+.I n
+should be rounded up to the next multiple greater than or equal to
+.IR (2k+1)*sizeof(size_t) ,
+where
+.I k
+is an integer.
+.\" Bins are multiples of 2 * sizeof(size_t) + sizeof(size_t)
+.P
+If
+.BR mallopt ()
+is used to set
+.BR M_PERTURB ,
+then, as expected, the bytes of allocated memory are initialized
+to the complement of the byte in
+.IR value ,
+and when that memory is freed,
+the bytes of the region are initialized to the byte specified in
+.IR value .
+However, there is an
+.RI off-by- sizeof(size_t)
+error in the implementation:
+.\" FIXME . https://www.sourceware.org/bugzilla/show_bug.cgi?id=12140
+instead of initializing precisely the block of memory
+being freed by the call
+.IR free(p) ,
+the block starting at
+.I p+sizeof(size_t)
+is initialized.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR M_CHECK_ACTION .
+If the program is supplied with an (integer) command-line argument,
+then that argument is used to set the
+.B M_CHECK_ACTION
+parameter.
+The program then allocates a block of memory,
+and frees it twice (an error).
+.P
+The following shell session shows what happens when we run this program
+under glibc, with the default value for
+.BR M_CHECK_ACTION :
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+main(): returned from first free() call
+*** glibc detected *** ./a.out: double free or corruption (top): 0x09d30008 ***
+======= Backtrace: =========
+/lib/libc.so.6(+0x6c501)[0x523501]
+/lib/libc.so.6(+0x6dd70)[0x524d70]
+/lib/libc.so.6(cfree+0x6d)[0x527e5d]
+\&./a.out[0x80485db]
+/lib/libc.so.6(__libc_start_main+0xe7)[0x4cdce7]
+\&./a.out[0x8048471]
+======= Memory map: ========
+001e4000\-001fe000 r\-xp 00000000 08:06 1083555    /lib/libgcc_s.so.1
+001fe000\-001ff000 r\-\-p 00019000 08:06 1083555    /lib/libgcc_s.so.1
+[some lines omitted]
+b7814000\-b7817000 rw\-p 00000000 00:00 0
+bff53000\-bff74000 rw\-p 00000000 00:00 0          [stack]
+Aborted (core dumped)
+.EE
+.in
+.P
+The following runs show the results when employing other values for
+.BR M_CHECK_ACTION :
+.P
+.in +4n
+.EX
+$ \fB./a.out 1\fP             # Diagnose error and continue
+main(): returned from first free() call
+*** glibc detected *** ./a.out: double free or corruption (top): 0x09cbe008 ***
+main(): returned from second free() call
+$ \fB./a.out 2\fP             # Abort without error message
+main(): returned from first free() call
+Aborted (core dumped)
+$ \fB./a.out 0\fP             # Ignore error and continue
+main(): returned from first free() call
+main(): returned from second free() call
+.EE
+.in
+.P
+The next run shows how to set the same parameter using the
+.B MALLOC_CHECK_
+environment variable:
+.P
+.in +4n
+.EX
+$ \fBMALLOC_CHECK_=1 ./a.out\fP
+main(): returned from first free() call
+*** glibc detected *** ./a.out: free(): invalid pointer: 0x092c2008 ***
+main(): returned from second free() call
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (mallopt.c)
+.EX
+#include <malloc.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    char *p;
+\&
+    if (argc > 1) {
+        if (mallopt(M_CHECK_ACTION, atoi(argv[1])) != 1) {
+            fprintf(stderr, "mallopt() failed");
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    p = malloc(1000);
+    if (p == NULL) {
+        fprintf(stderr, "malloc() failed");
+        exit(EXIT_FAILURE);
+    }
+\&
+    free(p);
+    printf("%s(): returned from first free() call\en", __func__);
+\&
+    free(p);
+    printf("%s(): returned from second free() call\en", __func__);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR mmap (2),
+.BR sbrk (2),
+.BR mallinfo (3),
+.BR malloc (3),
+.BR malloc_hook (3),
+.BR malloc_info (3),
+.BR malloc_stats (3),
+.BR malloc_trim (3),
+.BR mcheck (3),
+.BR mtrace (3),
+.BR posix_memalign (3)
diff --git a/man/man3/matherr.3 b/man/man3/matherr.3
new file mode 100644
index 000000000..66b2f0fe8
--- /dev/null
+++ b/man/man3/matherr.3
@@ -0,0 +1,428 @@
+'\" t
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH matherr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+matherr \- SVID math library exception handling
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "[[deprecated]] int matherr(struct exception *" exc );
+.P
+.B [[deprecated]] extern _LIB_VERSION_TYPE _LIB_VERSION;
+.fi
+.SH DESCRIPTION
+.IR Note :
+the mechanism described in this page is no longer supported by glibc.
+Before glibc 2.27, it had been marked as obsolete.
+Since glibc 2.27,
+.\" glibc commit 813378e9fe17e029caf627cab76fe23eb46815fa
+the mechanism has been removed altogether.
+New applications should use the techniques described in
+.BR math_error (7)
+and
+.BR fenv (3).
+This page documents the
+.BR matherr ()
+mechanism as an aid for maintaining and porting older applications.
+.P
+The System V Interface Definition (SVID) specifies that various
+math functions should invoke a function called
+.BR matherr ()
+if a math exception is detected.
+This function is called before the math function returns;
+after
+.BR matherr ()
+returns, the system then returns to the math function,
+which in turn returns to the caller.
+.P
+To employ
+.BR matherr (),
+the programmer must define the
+.B _SVID_SOURCE
+feature test macro
+(before including
+.I any
+header files),
+and assign the value
+.B _SVID_
+to the external variable
+.BR _LIB_VERSION .
+.P
+The system provides a default version of
+.BR matherr ().
+This version does nothing, and returns zero
+(see below for the significance of this).
+The default
+.BR matherr ()
+can be overridden by a programmer-defined
+version, which will be invoked when an exception occurs.
+The function is invoked with one argument, a pointer to an
+.I exception
+structure, defined as follows:
+.P
+.in +4n
+.EX
+struct exception {
+    int    type;      /* Exception type */
+    char  *name;      /* Name of function causing exception */
+    double arg1;      /* 1st argument to function */
+    double arg2;      /* 2nd argument to function */
+    double retval;    /* Function return value */
+}
+.EE
+.in
+.P
+The
+.I type
+field has one of the following values:
+.TP 12
+.B DOMAIN
+A domain error occurred (the function argument was outside the range
+for which the function is defined).
+The return value depends on the function;
+.I errno
+is set to
+.BR EDOM .
+.TP
+.B SING
+A pole error occurred (the function result is an infinity).
+The return value in most cases is
+.B HUGE
+(the largest single precision floating-point number),
+appropriately signed.
+In most cases,
+.I errno
+is set to
+.BR EDOM .
+.TP
+.B OVERFLOW
+An overflow occurred.
+In most cases, the value
+.B HUGE
+is returned, and
+.I errno
+is set to
+.BR ERANGE .
+.TP
+.B UNDERFLOW
+An underflow occurred.
+0.0 is returned, and
+.I errno
+is set to
+.BR ERANGE .
+.TP
+.B TLOSS
+Total loss of significance.
+0.0 is returned, and
+.I errno
+is set to
+.BR ERANGE .
+.TP
+.B PLOSS
+Partial loss of significance.
+This value is unused on glibc
+(and many other systems).
+.P
+The
+.I arg1
+and
+.I arg2
+fields are the arguments supplied to the function
+.RI ( arg2
+is undefined for functions that take only one argument).
+.P
+The
+.I retval
+field specifies the return value that the math
+function will return to its caller.
+The programmer-defined
+.BR matherr ()
+can modify this field to change the return value of the math function.
+.P
+If the
+.BR matherr ()
+function returns zero, then the system sets
+.I errno
+as described above, and may print an error message on standard error
+(see below).
+.P
+If the
+.BR matherr ()
+function returns a nonzero value, then the system does not set
+.IR errno ,
+and doesn't print an error message.
+.SS Math functions that employ matherr()
+The table below lists the functions and circumstances in which
+.BR matherr ()
+is called.
+The "Type" column indicates the value assigned to
+.I exc\->type
+when calling
+.BR matherr ().
+The "Result" column is the default return value assigned to
+.IR exc\->retval .
+.P
+The "Msg?" and "errno" columns describe the default behavior if
+.BR matherr ()
+returns zero.
+If the "Msg?" columns contains "y",
+then the system prints an error message on standard error.
+.P
+The table uses the following notations and abbreviations:
+.P
+.RS
+.TS
+l l.
+x        first argument to function
+y        second argument to function
+fin      finite value for argument
+neg      negative value for argument
+int      integral value for argument
+o/f      result overflowed
+u/f      result underflowed
+|x|      absolute value of x
+X_TLOSS  is a constant defined in \fI<math.h>\fP
+.TE
+.RE
+.\" Details below from glibc 2.8's sysdeps/ieee754/k_standard.c
+.\" A subset of cases were test by experimental programs.
+.TS
+lB lB lB cB lB
+l l l c l.
+Function	Type	Result	Msg?	errno
+acos(|x|>1)	DOMAIN	HUGE	y	EDOM
+asin(|x|>1)	DOMAIN	HUGE	y	EDOM
+atan2(0,0)	DOMAIN	HUGE	y	EDOM
+acosh(x<1)	DOMAIN	NAN	y	EDOM	\" retval is 0.0/0.0
+atanh(|x|>1)	DOMAIN	NAN	y	EDOM	\" retval is 0.0/0.0
+atanh(|x|==1)	SING	(x>0.0)?	y	EDOM	\" retval is x/0.0
+\ 	\ 	HUGE_VAL :
+\ 	\ 	\-HUGE_VAL
+cosh(fin) o/f	OVERFLOW	HUGE	n	ERANGE
+sinh(fin) o/f	OVERFLOW	(x>0.0) ?	n	ERANGE
+\ 	\ 	HUGE : \-HUGE
+sqrt(x<0)	DOMAIN	0.0	y	EDOM
+hypot(fin,fin) o/f	OVERFLOW	HUGE	n	ERANGE
+exp(fin) o/f	OVERFLOW	HUGE	n	ERANGE
+exp(fin) u/f	UNDERFLOW	0.0	n	ERANGE
+exp2(fin) o/f	OVERFLOW	HUGE	n	ERANGE
+exp2(fin) u/f	UNDERFLOW	0.0	n	ERANGE
+exp10(fin) o/f	OVERFLOW	HUGE	n	ERANGE
+exp10(fin) u/f	UNDERFLOW	0.0	n	ERANGE
+j0(|x|>X_TLOSS)	TLOSS	0.0	y	ERANGE
+j1(|x|>X_TLOSS)	TLOSS	0.0	y	ERANGE
+jn(|x|>X_TLOSS)	TLOSS	0.0	y	ERANGE
+y0(x>X_TLOSS)	TLOSS	0.0	y	ERANGE
+y1(x>X_TLOSS)	TLOSS	0.0	y	ERANGE
+yn(x>X_TLOSS)	TLOSS	0.0	y	ERANGE
+y0(0)	DOMAIN	\-HUGE	y	EDOM
+y0(x<0)	DOMAIN	\-HUGE	y	EDOM
+y1(0)	DOMAIN	\-HUGE	y	EDOM
+y1(x<0)	DOMAIN	\-HUGE	y	EDOM
+yn(n,0)	DOMAIN	\-HUGE	y	EDOM
+yn(x<0)	DOMAIN	\-HUGE	y	EDOM
+lgamma(fin) o/f	OVERFLOW	HUGE	n	ERANGE
+lgamma(\-int) or	SING	HUGE	y	EDOM
+\ \ lgamma(0)
+tgamma(fin) o/f	OVERFLOW	HUGE_VAL	n	ERANGE
+tgamma(\-int)	SING	NAN	y	EDOM
+tgamma(0)	SING	copysign(	y	ERANGE
+\ 	\ 	HUGE_VAL,x)
+log(0)	SING	\-HUGE	y	EDOM
+log(x<0)	DOMAIN	\-HUGE	y	EDOM
+log2(0)	SING	\-HUGE	n	EDOM	\" different from log()
+log2(x<0)	DOMAIN	\-HUGE	n	EDOM	\" different from log()
+log10(0)	SING	\-HUGE	y	EDOM
+log10(x<0)	DOMAIN	\-HUGE	y	EDOM
+pow(0.0,0.0)	DOMAIN	0.0	y	EDOM
+pow(x,y) o/f	OVERFLOW	HUGE	n	ERANGE
+pow(x,y) u/f	UNDERFLOW	0.0	n	ERANGE
+pow(NaN,0.0)	DOMAIN	x	n	EDOM
+0**neg	DOMAIN	0.0	y	EDOM	\" +0 and -0
+neg**non-int	DOMAIN	0.0	y	EDOM
+scalb() o/f	OVERFLOW	(x>0.0) ?	n	ERANGE
+\ 	\ 	HUGE_VAL :
+\ 	\ 	\-HUGE_VAL
+scalb() u/f	UNDERFLOW	copysign(	n	ERANGE
+\ 	\ 	\ \ 0.0,x)
+fmod(x,0)	DOMAIN	x	y	EDOM
+remainder(x,0)	DOMAIN	NAN	y	EDOM	\" retval is 0.0/0.0
+.TE
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR matherr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH EXAMPLES
+The example program demonstrates the use of
+.BR matherr ()
+when calling
+.BR log (3).
+The program takes up to three command-line arguments.
+The first argument is the floating-point number to be given to
+.BR log (3).
+If the optional second argument is provided, then
+.B _LIB_VERSION
+is set to
+.B _SVID_
+so that
+.BR matherr ()
+is called, and the integer supplied in the
+command-line argument is used as the return value from
+.BR matherr ().
+If the optional third command-line argument is supplied,
+then it specifies an alternative return value that
+.BR matherr ()
+should assign as the return value of the math function.
+.P
+The following example run, where
+.BR log (3)
+is given an argument of 0.0, does not use
+.BR matherr ():
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 0.0"
+errno: Numerical result out of range
+x=\-inf
+.EE
+.in
+.P
+In the following run,
+.BR matherr ()
+is called, and returns 0:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 0.0 0"
+matherr SING exception in log() function
+        args:   0.000000, 0.000000
+        retval: \-340282346638528859811704183484516925440.000000
+log: SING error
+errno: Numerical argument out of domain
+x=\-340282346638528859811704183484516925440.000000
+.EE
+.in
+.P
+The message "log: SING error" was printed by the C library.
+.P
+In the following run,
+.BR matherr ()
+is called, and returns a nonzero value:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 0.0 1"
+matherr SING exception in log() function
+        args:   0.000000, 0.000000
+        retval: \-340282346638528859811704183484516925440.000000
+x=\-340282346638528859811704183484516925440.000000
+.EE
+.in
+.P
+In this case, the C library did not print a message, and
+.I errno
+was not set.
+.P
+In the following run,
+.BR matherr ()
+is called, changes the return value of the math function,
+and returns a nonzero value:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 0.0 1 12345.0"
+matherr SING exception in log() function
+        args:   0.000000, 0.000000
+        retval: \-340282346638528859811704183484516925440.000000
+x=12345.000000
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (matherr.c)
+.EX
+#define _SVID_SOURCE
+#include <errno.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+static int matherr_ret = 0;     /* Value that matherr()
+                                   should return */
+static int change_retval = 0;   /* Should matherr() change
+                                   function\[aq]s return value? */
+static double new_retval;       /* New function return value */
+\&
+int
+matherr(struct exception *exc)
+{
+    fprintf(stderr, "matherr %s exception in %s() function\en",
+            (exc\->type == DOMAIN) ?    "DOMAIN" :
+            (exc\->type == OVERFLOW) ?  "OVERFLOW" :
+            (exc\->type == UNDERFLOW) ? "UNDERFLOW" :
+            (exc\->type == SING) ?      "SING" :
+            (exc\->type == TLOSS) ?     "TLOSS" :
+            (exc\->type == PLOSS) ?     "PLOSS" : "???",
+            exc\->name);
+    fprintf(stderr, "        args:   %f, %f\en",
+            exc\->arg1, exc\->arg2);
+    fprintf(stderr, "        retval: %f\en", exc\->retval);
+\&
+    if (change_retval)
+        exc\->retval = new_retval;
+\&
+    return matherr_ret;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    double x;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <argval>"
+                " [<matherr\-ret> [<new\-func\-retval>]]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (argc > 2) {
+        _LIB_VERSION = _SVID_;
+        matherr_ret = atoi(argv[2]);
+    }
+\&
+    if (argc > 3) {
+        change_retval = 1;
+        new_retval = atof(argv[3]);
+    }
+\&
+    x = log(atof(argv[1]));
+    if (errno != 0)
+        perror("errno");
+\&
+    printf("x=%f\en", x);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fenv (3),
+.BR math_error (7),
+.BR standards (7)
diff --git a/man/man3/mblen.3 b/man/man3/mblen.3
new file mode 100644
index 000000000..c2e421de9
--- /dev/null
+++ b/man/man3/mblen.3
@@ -0,0 +1,117 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH mblen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mblen \- determine number of bytes in next multibyte character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int mblen(const char " s [. n "], size_t " n );
+.fi
+.SH DESCRIPTION
+If
+.I s
+is not NULL, the
+.BR mblen ()
+function inspects at most
+.I n
+bytes of the multibyte string starting at
+.I s
+and extracts the
+next complete multibyte character.
+It uses a static anonymous shift state known only to the
+.BR mblen ()
+function.
+If the multibyte character is not the null wide
+character, it returns the number of bytes that were consumed from
+.IR s .
+If the multibyte character is the null wide character, it returns 0.
+.P
+If the
+.I n
+bytes starting at
+.I s
+do not contain a complete multibyte
+character,
+.BR mblen ()
+returns \-1.
+This can happen even if
+.I n
+is greater than or equal to
+.IR MB_CUR_MAX ,
+if the multibyte string contains redundant shift sequences.
+.P
+If the multibyte string starting at
+.I s
+contains an invalid multibyte
+sequence before the next complete character,
+.BR mblen ()
+also returns \-1.
+.P
+If
+.I s
+is NULL, the
+.BR mblen ()
+function
+.\" The Dinkumware doc and the Single UNIX specification say this, but
+.\" glibc doesn't implement this.
+resets the shift state, known to only this function, to the initial state, and
+returns nonzero if the encoding has nontrivial shift state, or zero if the
+encoding is stateless.
+.SH RETURN VALUE
+The
+.BR mblen ()
+function returns the number of
+bytes parsed from the multibyte
+sequence starting at
+.IR s ,
+if a non-null wide character was recognized.
+It returns 0, if a null wide character was recognized.
+It returns \-1, if an
+invalid multibyte sequence was encountered or if it couldn't parse a complete
+multibyte character.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mblen ()
+T}	Thread safety	MT-Unsafe race
+.TE
+.SH VERSIONS
+The function
+.BR mbrlen (3)
+provides a better interface to the same
+functionality.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR mblen ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR mbrlen (3)
diff --git a/man/man3/mbrlen.3 b/man/man3/mbrlen.3
new file mode 100644
index 000000000..ae147f2bb
--- /dev/null
+++ b/man/man3/mbrlen.3
@@ -0,0 +1,130 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH mbrlen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbrlen \- determine number of bytes in next multibyte character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t mbrlen(const char " s "[restrict ." n "], size_t " n ,
+.BI "              mbstate_t *restrict " ps );
+.fi
+.SH DESCRIPTION
+The
+.BR mbrlen ()
+function inspects at most
+.I n
+bytes of the multibyte
+string starting at
+.I s
+and extracts the next complete multibyte character.
+It updates the shift state
+.IR *ps .
+If the multibyte character is not the
+null wide character, it returns the number of bytes that were consumed from
+.IR s .
+If the multibyte character is the null wide character, it resets the
+shift state
+.I *ps
+to the initial state and returns 0.
+.P
+If the
+.I n
+bytes starting at
+.I s
+do not contain a complete multibyte
+character,
+.BR mbrlen ()
+returns
+.IR "(size_t)\ \-2" .
+This can happen even if
+.I n
+>=
+.IR MB_CUR_MAX ,
+if the multibyte string contains redundant shift
+sequences.
+.P
+If the multibyte string starting at
+.I s
+contains an invalid multibyte
+sequence before the next complete character,
+.BR mbrlen ()
+returns
+.I (size_t)\ \-1
+and sets
+.I errno
+to
+.BR EILSEQ .
+In this case,
+the effects on
+.I *ps
+are undefined.
+.P
+If
+.I ps
+is NULL, a static anonymous state known only to the
+.BR mbrlen ()
+function is used instead.
+.SH RETURN VALUE
+The
+.BR mbrlen ()
+function returns the number of bytes
+parsed from the multibyte
+sequence starting at
+.IR s ,
+if a non-null wide character was recognized.
+It returns 0, if a null wide character was recognized.
+It returns
+.I "(size_t)\ \-1"
+and sets
+.I errno
+to
+.BR EILSEQ ,
+if an invalid multibyte sequence was
+encountered.
+It returns
+.I (size_t)\ \-2
+if it couldn't parse a complete multibyte
+character, meaning that
+.I n
+should be increased.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mbrlen ()
+T}	Thread safety	MT-Unsafe race:mbrlen/!ps
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR mbrlen ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR mbrtowc (3)
diff --git a/man/man3/mbrtowc.3 b/man/man3/mbrtowc.3
new file mode 100644
index 000000000..26d29b255
--- /dev/null
+++ b/man/man3/mbrtowc.3
@@ -0,0 +1,201 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification
+.\"      http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH mbrtowc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbrtowc \- convert a multibyte sequence to a wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t mbrtowc(wchar_t *restrict " pwc ", const char " s "[restrict ." n ],
+.BI "               size_t " n ", mbstate_t *restrict " ps );
+.fi
+.SH DESCRIPTION
+The main case for this function is when
+.I s
+is not NULL and
+.I pwc
+is
+not NULL.
+In this case, the
+.BR mbrtowc ()
+function inspects at most
+.I n
+bytes of the multibyte string starting at
+.IR s ,
+extracts the next complete
+multibyte character, converts it to a wide character and stores it at
+.IR *pwc .
+It updates the shift state
+.IR *ps .
+If the converted wide
+character is not L\[aq]\e0\[aq] (the null wide character),
+it returns the number of bytes that were consumed
+from
+.IR s .
+If the converted wide character is L\[aq]\e0\[aq], it resets the shift
+state
+.I *ps
+to the initial state and returns 0.
+.P
+If the
+.I n
+bytes starting at
+.I s
+do not contain a complete multibyte
+character,
+.BR mbrtowc ()
+returns
+.IR "(size_t)\ \-2" .
+This can happen even if
+.I n
+>=
+.IR MB_CUR_MAX ,
+if the multibyte string contains redundant shift
+sequences.
+.P
+If the multibyte string starting at
+.I s
+contains an invalid multibyte
+sequence before the next complete character,
+.BR mbrtowc ()
+returns
+.I (size_t)\ \-1
+and sets
+.I errno
+to
+.BR EILSEQ .
+In this case,
+the effects on
+.I *ps
+are undefined.
+.P
+A different case is when
+.I s
+is not NULL but
+.I pwc
+is NULL.
+In this case, the
+.BR mbrtowc ()
+function behaves as above, except that it does not
+store the converted wide character in memory.
+.P
+A third case is when
+.I s
+is NULL.
+In this case,
+.I pwc
+and
+.I n
+are
+ignored.
+If the conversion state represented by
+.I *ps
+denotes an
+incomplete multibyte character conversion, the
+.BR mbrtowc ()
+function
+returns
+.IR "(size_t)\ \-1" ,
+sets
+.I errno
+to
+.BR EILSEQ ,
+and
+leaves
+.I *ps
+in an undefined state.
+Otherwise, the
+.BR mbrtowc ()
+function
+puts
+.I *ps
+in the initial state and returns 0.
+.P
+In all of the above cases, if
+.I ps
+is NULL, a static anonymous
+state known only to the
+.BR mbrtowc ()
+function is used instead.
+Otherwise,
+.I *ps
+must be a valid
+.I mbstate_t
+object.
+An
+.I mbstate_t
+object
+.I a
+can be initialized to the initial state
+by zeroing it, for example using
+.P
+.in +4n
+.EX
+memset(&a, 0, sizeof(a));
+.EE
+.in
+.SH RETURN VALUE
+The
+.BR mbrtowc ()
+function returns the number of bytes parsed from the
+multibyte sequence starting at
+.IR s ,
+if a non-L\[aq]\e0\[aq] wide character
+was recognized.
+It returns 0, if a L\[aq]\e0\[aq] wide character was recognized.
+It returns
+.I (size_t)\ \-1
+and sets
+.I errno
+to
+.BR EILSEQ ,
+if an invalid multibyte sequence was
+encountered.
+It returns
+.I "(size_t)\ \-2"
+if it couldn't parse a complete multibyte
+character, meaning that
+.I n
+should be increased.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mbrtowc ()
+T}	Thread safety	MT-Unsafe race:mbrtowc/!ps
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR mbrtowc ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR mbsinit (3),
+.BR mbsrtowcs (3)
diff --git a/man/man3/mbsinit.3 b/man/man3/mbsinit.3
new file mode 100644
index 000000000..3ace32b69
--- /dev/null
+++ b/man/man3/mbsinit.3
@@ -0,0 +1,117 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH mbsinit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbsinit \- test for initial shift state
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int mbsinit(const mbstate_t *" ps );
+.fi
+.SH DESCRIPTION
+Character conversion between the multibyte representation and the wide
+character representation uses conversion state, of type
+.IR mbstate_t .
+Conversion of a string uses a finite-state machine; when it is interrupted
+after the complete conversion of a number of characters, it may need to
+save a state for processing the remaining characters.
+Such a conversion
+state is needed for the sake of encodings such as ISO/IEC\~2022 and UTF-7.
+.P
+The initial state is the state at the beginning of conversion of a string.
+There are two kinds of state: the one used by multibyte to wide character
+conversion functions, such as
+.BR mbsrtowcs (3),
+and the one used by wide
+character to multibyte conversion functions, such as
+.BR wcsrtombs (3),
+but they both fit in a
+.IR mbstate_t ,
+and they both have the same
+representation for an initial state.
+.P
+For 8-bit encodings, all states are equivalent to the initial state.
+For multibyte encodings like UTF-8, EUC-*, BIG5, or SJIS, the wide character
+to multibyte conversion functions never produce non-initial states, but the
+multibyte to wide-character conversion functions like
+.BR mbrtowc (3)
+do
+produce non-initial states when interrupted in the middle of a character.
+.P
+One possible way to create an
+.I mbstate_t
+in initial state is to set it to zero:
+.P
+.in +4n
+.EX
+mbstate_t state;
+memset(&state, 0, sizeof(state));
+.EE
+.in
+.P
+On Linux, the following works as well, but might generate compiler warnings:
+.P
+.in +4n
+.EX
+mbstate_t state = { 0 };
+.EE
+.in
+.P
+The function
+.BR mbsinit ()
+tests whether
+.I *ps
+corresponds to an
+initial state.
+.SH RETURN VALUE
+.BR mbsinit ()
+returns nonzero if
+.I *ps
+is an initial state, or if
+.I ps
+is NULL.
+Otherwise, it returns 0.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mbsinit ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR mbsinit ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR mbrlen (3),
+.BR mbrtowc (3),
+.BR mbsrtowcs (3),
+.BR wcrtomb (3),
+.BR wcsrtombs (3)
diff --git a/man/man3/mbsnrtowcs.3 b/man/man3/mbsnrtowcs.3
new file mode 100644
index 000000000..a8447e594
--- /dev/null
+++ b/man/man3/mbsnrtowcs.3
@@ -0,0 +1,199 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH mbsnrtowcs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbsnrtowcs \- convert a multibyte string to a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t mbsnrtowcs(wchar_t " dest "[restrict ." len "], const char **restrict " src ,
+.BI "                  size_t " nms ", size_t " len \
+", mbstate_t *restrict " ps );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mbsnrtowcs ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR mbsnrtowcs ()
+function is like the
+.BR mbsrtowcs (3)
+function, except that
+the number of bytes to be converted, starting at
+.IR *src ,
+is limited to at most
+.I nms
+bytes.
+.P
+If
+.I dest
+is not NULL, the
+.BR mbsnrtowcs ()
+function converts at
+most
+.I nms
+bytes from the
+multibyte string
+.I *src
+to a wide-character string starting at
+.IR dest .
+At most
+.I len
+wide characters are written to
+.IR dest .
+The shift state
+.I *ps
+is updated.
+The conversion is effectively performed by repeatedly
+calling
+.I "mbrtowc(dest, *src, n, ps)"
+where
+.I n
+is some
+positive number, as long as this call succeeds, and then incrementing
+.I dest
+by one and
+.I *src
+by the number of bytes consumed.
+The
+conversion can stop for three reasons:
+.IP \[bu] 3
+An invalid multibyte sequence has been encountered.
+In this case,
+.I *src
+is left pointing to the invalid multibyte sequence,
+.I (size_t)\ \-1
+is returned,
+and
+.I errno
+is set to
+.BR EILSEQ .
+.IP \[bu]
+The
+.I nms
+limit forces a stop,
+or
+.I len
+non-L\[aq]\e0\[aq] wide characters
+have been stored at
+.IR dest .
+In this case,
+.I *src
+is left pointing to the
+next multibyte sequence to be converted, and the number of wide characters
+written to
+.I dest
+is returned.
+.IP \[bu]
+The multibyte string has been completely converted, including the
+terminating null wide character (\[aq]\e0\[aq])
+(which has the side effect of bringing back
+.I *ps
+to the
+initial state).
+In this case,
+.I *src
+is set to NULL, and the number of wide
+characters written to
+.IR dest ,
+excluding the terminating null wide character,
+is returned.
+.P
+According to POSIX.1,
+if the input buffer ends with an incomplete character,
+it is unspecified whether conversion stops at the end of
+the previous character (if any), or at the end of the input buffer.
+The glibc implementation adopts the former behavior.
+.P
+If
+.I dest
+is NULL,
+.I len
+is ignored, and the conversion proceeds as
+above, except that the converted wide characters
+are not written out to memory,
+and that no destination length limit exists.
+.P
+In both of the above cases, if
+.I ps
+is NULL, a static anonymous
+state known only to the
+.BR mbsnrtowcs ()
+function is used instead.
+.P
+The programmer must ensure that there is room for at least
+.I len
+wide
+characters at
+.IR dest .
+.SH RETURN VALUE
+The
+.BR mbsnrtowcs ()
+function returns the number of wide characters
+that make up the converted part of the wide-character string,
+not including the terminating null wide character.
+If an invalid multibyte sequence was
+encountered,
+.I (size_t)\ \-1
+is returned, and
+.I errno
+set to
+.BR EILSEQ .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mbsnrtowcs ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:mbsnrtowcs/!ps
+T}
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH NOTES
+The behavior of
+.BR mbsnrtowcs ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+Passing NULL as
+.I ps
+is not multithread safe.
+.SH SEE ALSO
+.BR iconv (3),
+.BR mbrtowc (3),
+.BR mbsinit (3),
+.BR mbsrtowcs (3)
diff --git a/man/man3/mbsrtowcs.3 b/man/man3/mbsrtowcs.3
new file mode 100644
index 000000000..f061672b7
--- /dev/null
+++ b/man/man3/mbsrtowcs.3
@@ -0,0 +1,170 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH mbsrtowcs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbsrtowcs \- convert a multibyte string to a wide-character string (restartable)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t mbsrtowcs(wchar_t " dest "[restrict ." dsize ],
+.BI "                 const char **restrict " src ,
+.BI "                 size_t " dsize ", mbstate_t *restrict " ps );
+.fi
+.SH DESCRIPTION
+If
+.I dest
+is not NULL,
+convert the
+multibyte string
+.I *src
+to a wide-character string starting at
+.IR dest .
+At most
+.I dsize
+wide characters are written to
+.IR dest .
+The shift state
+.I *ps
+is updated.
+The conversion is effectively performed by repeatedly
+calling
+.I "mbrtowc(dest, *src, n, ps)"
+where
+.I n
+is some
+positive number, as long as this call succeeds, and then incrementing
+.I dest
+by one and
+.I *src
+by the number of bytes consumed.
+The conversion can stop for three reasons:
+.IP \[bu] 3
+An invalid multibyte sequence has been encountered.
+In this case,
+.I *src
+is left pointing to the invalid multibyte sequence,
+.I (size_t)\ \-1
+is returned,
+and
+.I errno
+is set to
+.BR EILSEQ .
+.IP \[bu]
+.I dsize
+non-L\[aq]\e0\[aq] wide characters have been stored at
+.IR dest .
+In this case,
+.I *src
+is left pointing to the next
+multibyte sequence to be converted,
+and the number of wide characters written to
+.I dest
+is returned.
+.IP \[bu]
+The multibyte string has been completely converted, including the
+terminating null wide character (\[aq]\e0\[aq]), which has the side
+effect of bringing back
+.I *ps
+to the
+initial state.
+In this case,
+.I *src
+is set to NULL, and the number of wide
+characters written to
+.IR dest ,
+excluding the terminating null wide character, is returned.
+.P
+If
+.I dest
+is NULL,
+.I dsize
+is ignored,
+and the conversion proceeds as above,
+except that the converted wide characters are not written out to memory,
+and that no length limit exists.
+.P
+In both of the above cases,
+if
+.I ps
+is NULL, a static anonymous
+state known only to the
+.BR mbsrtowcs ()
+function is used instead.
+.P
+In order to avoid the case 2 above, the programmer should make sure
+.I dsize
+is
+greater than or equal to
+.IR "mbsrtowcs(NULL,src,0,ps)+1" .
+.P
+The programmer must ensure that there is room for at least
+.I dsize
+wide
+characters at
+.IR dest .
+.P
+This function is a restartable version of
+.BR mbstowcs (3).
+.SH RETURN VALUE
+The number of wide characters that make
+up the converted part of the wide-character string, not including the
+terminating null wide character.
+If an invalid multibyte sequence was
+encountered,
+.I (size_t)\ \-1
+is returned, and
+.I errno
+set to
+.BR EILSEQ .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mbsrtowcs ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:mbsrtowcs/!ps
+T}
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR mbsrtowcs ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+Passing NULL as
+.I ps
+is not multithread safe.
+.SH SEE ALSO
+.BR iconv (3),
+.BR mbrtowc (3),
+.BR mbsinit (3),
+.BR mbsnrtowcs (3),
+.BR mbstowcs (3)
diff --git a/man/man3/mbstowcs.3 b/man/man3/mbstowcs.3
new file mode 100644
index 000000000..f08ce3258
--- /dev/null
+++ b/man/man3/mbstowcs.3
@@ -0,0 +1,237 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\" and Copyright 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH mbstowcs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbstowcs \- convert a multibyte string to a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "size_t mbstowcs(wchar_t " dest "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "                size_t " dsize );
+.fi
+.SH DESCRIPTION
+If
+.I dest
+is not NULL,
+convert the
+multibyte string
+.I src
+to a wide-character string starting at
+.IR dest .
+At most
+.I dsize
+wide characters are written to
+.IR dest .
+The sequence of characters in the string
+.I src
+shall begin in the initial shift state.
+The conversion can stop for three reasons:
+.IP \[bu] 3
+An invalid multibyte sequence has been encountered.
+In this case,
+.I (size_t)\ \-1
+is returned.
+.IP \[bu]
+.I dsize
+non-L\[aq]\e0\[aq] wide characters have been stored at
+.IR dest .
+In this case, the number of wide characters written to
+.I dest
+is returned, but the
+shift state at this point is lost.
+.IP \[bu]
+The multibyte string has been completely converted, including the
+terminating null character (\[aq]\e0\[aq]).
+In this case, the number of wide characters written to
+.IR dest ,
+excluding the terminating null wide character, is returned.
+.P
+If
+.I dest
+is NULL,
+.I dsize
+is ignored, and the conversion proceeds as
+above, except that the converted wide characters are not written out to memory,
+and that no length limit exists.
+.P
+In order to avoid the case 2 above, the programmer should make sure
+.I dsize
+is
+greater than or equal to
+.IR "mbstowcs(NULL,src,0)+1" .
+.P
+The programmer must ensure that there is room for at least
+.I dsize
+wide
+characters at
+.IR dest .
+.SH RETURN VALUE
+The number of wide characters that make
+up the converted part of the wide-character string, not including the
+terminating null wide character.
+If an invalid multibyte sequence was
+encountered,
+.I (size_t)\ \-1
+is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mbstowcs ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The function
+.BR mbsrtowcs (3)
+provides a better interface to the same
+functionality.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR mbstowcs ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH EXAMPLES
+The program below illustrates the use of
+.BR mbstowcs (),
+as well as some of the wide character classification functions.
+An example run is the following:
+.P
+.in +4n
+.EX
+$ ./t_mbstowcs de_DE.UTF\-8 Grüße!
+Length of source string (excluding terminator):
+    8 bytes
+    6 multibyte characters
+\&
+Wide character string is: Grüße! (6 characters)
+    G alpha upper
+    r alpha lower
+    ü alpha lower
+    ß alpha lower
+    e alpha lower
+    ! !alpha
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (mbstowcs.c)
+.EX
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <wctype.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    size_t mbslen;      /* Number of multibyte characters in source */
+    wchar_t *wcs;       /* Pointer to converted wide character string */
+\&
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s <locale> <string>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Apply the specified locale. */
+\&
+    if (setlocale(LC_ALL, argv[1]) == NULL) {
+        perror("setlocale");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Calculate the length required to hold argv[2] converted to
+       a wide character string. */
+\&
+    mbslen = mbstowcs(NULL, argv[2], 0);
+    if (mbslen == (size_t) \-1) {
+        perror("mbstowcs");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Describe the source string to the user. */
+\&
+    printf("Length of source string (excluding terminator):\en");
+    printf("    %zu bytes\en", strlen(argv[2]));
+    printf("    %zu multibyte characters\en\en", mbslen);
+\&
+    /* Allocate wide character string of the desired size.  Add 1
+       to allow for terminating null wide character (L\[aq]\e0\[aq]). */
+\&
+    wcs = calloc(mbslen + 1, sizeof(*wcs));
+    if (wcs == NULL) {
+        perror("calloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Convert the multibyte character string in argv[2] to a
+       wide character string. */
+\&
+    if (mbstowcs(wcs, argv[2], mbslen + 1) == (size_t) \-1) {
+        perror("mbstowcs");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Wide character string is: %ls (%zu characters)\en",
+           wcs, mbslen);
+\&
+    /* Now do some inspection of the classes of the characters in
+       the wide character string. */
+\&
+    for (wchar_t *wp = wcs; *wp != 0; wp++) {
+        printf("    %lc ", (wint_t) *wp);
+\&
+        if (!iswalpha(*wp))
+            printf("!");
+        printf("alpha ");
+\&
+        if (iswalpha(*wp)) {
+            if (iswupper(*wp))
+                printf("upper ");
+\&
+            if (iswlower(*wp))
+                printf("lower ");
+        }
+\&
+        putchar(\[aq]\en\[aq]);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR mblen (3),
+.BR mbsrtowcs (3),
+.BR mbtowc (3),
+.BR wcstombs (3),
+.BR wctomb (3)
diff --git a/man/man3/mbtowc.3 b/man/man3/mbtowc.3
new file mode 100644
index 000000000..08739facb
--- /dev/null
+++ b/man/man3/mbtowc.3
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH mbtowc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mbtowc \- convert a multibyte sequence to a wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int mbtowc(wchar_t *restrict " pwc ", const char " s "[restrict ." n "], \
+size_t " n );
+.fi
+.SH DESCRIPTION
+The main case for this function is when
+.I s
+is not NULL and
+.I pwc
+is
+not NULL.
+In this case, the
+.BR mbtowc ()
+function inspects at most
+.I n
+bytes of the multibyte string starting at
+.IR s ,
+extracts the next complete
+multibyte character, converts it to a wide character and stores it at
+.IR *pwc .
+It updates an internal shift state known only to the
+.BR mbtowc ()
+function.
+If
+.I s
+does not point to a null byte (\[aq]\e0\[aq]), it returns the number
+of bytes that were consumed from
+.IR s ,
+otherwise it returns 0.
+.P
+If the
+.I n
+bytes starting at
+.I s
+do not contain a complete multibyte
+character, or if they contain an invalid multibyte sequence,
+.BR mbtowc ()
+returns \-1.
+This can happen even if
+.I n
+>=
+.IR MB_CUR_MAX ,
+if the multibyte string contains redundant shift sequences.
+.P
+A different case is when
+.I s
+is not NULL but
+.I pwc
+is NULL.
+In this case, the
+.BR mbtowc ()
+function behaves as above, except that it does not
+store the converted wide character in memory.
+.P
+A third case is when
+.I s
+is NULL.
+In this case,
+.I pwc
+and
+.I n
+are
+ignored.
+The
+.BR mbtowc ()
+function
+.\" The Dinkumware doc and the Single UNIX specification say this, but
+.\" glibc doesn't implement this.
+resets the shift state, only known to this function,
+to the initial state, and
+returns nonzero if the encoding has nontrivial shift state, or zero if the
+encoding is stateless.
+.SH RETURN VALUE
+If
+.I s
+is not NULL, the
+.BR mbtowc ()
+function returns the number of
+consumed bytes starting at
+.IR s ,
+or 0 if
+.I s
+points to a null byte,
+or \-1 upon failure.
+.P
+If
+.I s
+is NULL, the
+.BR mbtowc ()
+function
+returns nonzero if the encoding
+has nontrivial shift state, or zero if the encoding is stateless.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mbtowc ()
+T}	Thread safety	MT-Unsafe race
+.TE
+.SH VERSIONS
+This function is not multithread safe.
+The function
+.BR mbrtowc (3)
+provides
+a better interface to the same functionality.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR mbtowc ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR MB_CUR_MAX (3),
+.BR mblen (3),
+.BR mbrtowc (3),
+.BR mbstowcs (3),
+.BR wcstombs (3),
+.BR wctomb (3)
diff --git a/man/man3/mcheck.3 b/man/man3/mcheck.3
new file mode 100644
index 000000000..4b2920c19
--- /dev/null
+++ b/man/man3/mcheck.3
@@ -0,0 +1,213 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mcheck 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mcheck, mcheck_check_all, mcheck_pedantic, mprobe \- heap consistency checking
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <mcheck.h>
+.P
+.BI "int mcheck(void (*" abortfunc ")(enum mcheck_status " mstatus ));
+.BI "int mcheck_pedantic(void (*" abortfunc ")(enum mcheck_status " mstatus ));
+.B void mcheck_check_all(void);
+.P
+.BI "enum mcheck_status mprobe(void *" ptr );
+.fi
+.SH DESCRIPTION
+The
+.BR mcheck ()
+function installs a set of debugging hooks for the
+.BR malloc (3)
+family of memory-allocation functions.
+These hooks cause certain consistency checks to be performed
+on the state of the heap.
+The checks can detect application errors such as freeing a block of memory
+more than once or corrupting the bookkeeping data structures
+that immediately precede a block of allocated memory.
+.P
+To be effective, the
+.BR mcheck ()
+function must be called before the first call to
+.BR malloc (3)
+or a related function.
+In cases where this is difficult to ensure, linking the program with
+.I \-lmcheck
+inserts an implicit call to
+.BR mcheck ()
+(with a NULL argument)
+before the first call to a memory-allocation function.
+.P
+The
+.BR mcheck_pedantic ()
+function is similar to
+.BR mcheck (),
+but performs checks on all allocated blocks whenever
+one of the memory-allocation functions is called.
+This can be very slow!
+.P
+The
+.BR mcheck_check_all ()
+function causes an immediate check on all allocated blocks.
+This call is effective only if
+.BR mcheck ()
+is called beforehand.
+.P
+If the system detects an inconsistency in the heap,
+the caller-supplied function pointed to by
+.I abortfunc
+is invoked with a single argument,
+.IR mstatus ,
+that indicates what type of inconsistency was detected.
+If
+.I abortfunc
+is NULL, a default function prints an error message on
+.I stderr
+and calls
+.BR abort (3).
+.P
+The
+.BR mprobe ()
+function performs a consistency check on
+the block of allocated memory pointed to by
+.IR ptr .
+The
+.BR mcheck ()
+function should be called beforehand (otherwise
+.BR mprobe ()
+returns
+.BR MCHECK_DISABLED ).
+.P
+The following list describes the values returned by
+.BR mprobe ()
+or passed as the
+.I mstatus
+argument when
+.I abortfunc
+is invoked:
+.TP
+.BR MCHECK_DISABLED " (" mprobe "() only)"
+.BR mcheck ()
+was not called before the first memory allocation function was called.
+Consistency checking is not possible.
+.TP
+.BR MCHECK_OK " (" mprobe "() only)"
+No inconsistency detected.
+.TP
+.B MCHECK_HEAD
+Memory preceding an allocated block was clobbered.
+.TP
+.B MCHECK_TAIL
+Memory following an allocated block was clobbered.
+.TP
+.B
+MCHECK_FREE
+A block of memory was freed twice.
+.SH RETURN VALUE
+.BR mcheck ()
+and
+.BR mcheck_pedantic ()
+return 0 on success, or \-1 on error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mcheck (),
+.BR mcheck_pedantic (),
+.BR mcheck_check_all (),
+.BR mprobe ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:mcheck
+const:malloc_hooks
+T}
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+.TP
+.BR mcheck_pedantic ()
+.TQ
+.BR mcheck_check_all ()
+glibc 2.2.
+.TP
+.BR mcheck ()
+.TQ
+.BR mprobe ()
+glibc 2.0.
+.SH NOTES
+Linking a program with
+.I \-lmcheck
+and using the
+.B MALLOC_CHECK_
+environment variable (described in
+.BR mallopt (3))
+cause the same kinds of errors to be detected.
+But, using
+.B MALLOC_CHECK_
+does not require the application to be relinked.
+.\" But is MALLOC_CHECK_ slower?
+.SH EXAMPLES
+The program below calls
+.BR mcheck ()
+with a NULL argument and then frees the same block of memory twice.
+The following shell session demonstrates what happens
+when running the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+About to free
+\&
+About to free a second time
+block freed twice
+Aborted (core dumped)
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (mcheck.c)
+.EX
+#include <mcheck.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    char *p;
+\&
+    if (mcheck(NULL) != 0) {
+        fprintf(stderr, "mcheck() failed\en");
+\&
+        exit(EXIT_FAILURE);
+    }
+\&
+    p = malloc(1000);
+\&
+    fprintf(stderr, "About to free\en");
+    free(p);
+    fprintf(stderr, "\enAbout to free a second time\en");
+    free(p);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR malloc (3),
+.BR mallopt (3),
+.BR mtrace (3)
diff --git a/man/man3/mcheck_check_all.3 b/man/man3/mcheck_check_all.3
new file mode 100644
index 000000000..4baeaf2a5
--- /dev/null
+++ b/man/man3/mcheck_check_all.3
@@ -0,0 +1 @@
+.so man3/mcheck.3
diff --git a/man/man3/mcheck_pedantic.3 b/man/man3/mcheck_pedantic.3
new file mode 100644
index 000000000..4baeaf2a5
--- /dev/null
+++ b/man/man3/mcheck_pedantic.3
@@ -0,0 +1 @@
+.so man3/mcheck.3
diff --git a/man/man3/memalign.3 b/man/man3/memalign.3
new file mode 100644
index 000000000..791d4c801
--- /dev/null
+++ b/man/man3/memalign.3
@@ -0,0 +1 @@
+.so man3/posix_memalign.3
diff --git a/man/man3/memccpy.3 b/man/man3/memccpy.3
new file mode 100644
index 000000000..0ba805176
--- /dev/null
+++ b/man/man3/memccpy.3
@@ -0,0 +1,79 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:57:24 1993 by Rik Faith (faith@cs.unc.edu)
+.TH memccpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memccpy \- copy memory area
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "void *memccpy(void " dest "[restrict ." n "], const void " src "[restrict ." n ],
+.BI "              int " c ", size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR memccpy ()
+function copies no more than
+.I n
+bytes from
+memory area
+.I src
+to memory area
+.IR dest ,
+stopping when the
+character
+.I c
+is found.
+.P
+If the memory areas overlap, the results are undefined.
+.SH RETURN VALUE
+The
+.BR memccpy ()
+function returns a pointer to the next character
+in
+.I dest
+after
+.IR c ,
+or NULL if
+.I c
+was not found in the
+first
+.I n
+characters of
+.IR src .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memccpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR bcopy (3),
+.BR bstring (3),
+.BR memcpy (3),
+.BR memmove (3),
+.BR strcpy (3),
+.BR strncpy (3)
diff --git a/man/man3/memchr.3 b/man/man3/memchr.3
new file mode 100644
index 000000000..bb598c7d4
--- /dev/null
+++ b/man/man3/memchr.3
@@ -0,0 +1,142 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Mon Apr 12 12:49:57 1993, David Metcalfe
+.\" Modified Sat Jul 24 18:56:22 1993, Rik Faith (faith@cs.unc.edu)
+.\" Modified Wed Feb 20 21:09:36 2002, Ian Redfern (redferni@logica.com)
+.\" 2008-07-09, mtk, add rawmemchr()
+.\"
+.TH memchr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memchr, memrchr, rawmemchr \- scan memory for a character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "void *memchr(const void " s [. n "], int " c ", size_t " n );
+.BI "void *memrchr(const void " s [. n "], int " c ", size_t " n );
+.P
+.BI "[[deprecated]] void *rawmemchr(const void *" s ", int " c );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR memrchr (),
+.BR rawmemchr ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR memchr ()
+function scans the initial
+.I n
+bytes of the memory
+area pointed to by
+.I s
+for the first instance of
+.IR c .
+Both
+.I c
+and the bytes of the memory area pointed to by
+.I s
+are interpreted as
+.IR "unsigned char" .
+.P
+The
+.BR memrchr ()
+function is like the
+.BR memchr ()
+function,
+except that it searches backward from the end of the
+.I n
+bytes pointed to by
+.I s
+instead of forward from the beginning.
+.P
+The
+.BR rawmemchr ()
+function is similar to
+.BR memchr (),
+but it assumes
+(i.e., the programmer knows for certain)
+that an instance of
+.I c
+lies somewhere in the memory area starting at the location pointed to by
+.IR s .
+If an instance of
+.I c
+is not found, the behavior is undefined.
+Use either
+.BR strlen (3)
+or
+.BR memchr (3)
+instead.
+.SH RETURN VALUE
+The
+.BR memchr ()
+and
+.BR memrchr ()
+functions return a pointer
+to the matching byte or NULL if the character does not occur in
+the given memory area.
+.P
+The
+.BR rawmemchr ()
+function returns a pointer to the matching byte.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memchr (),
+.BR memrchr (),
+.BR rawmemchr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR memchr ()
+C11, POSIX.1-2008.
+.TP
+.BR memrchr ()
+.TQ
+.BR rawmemchr ()
+GNU.
+.SH HISTORY
+.TP
+.BR memchr ()
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.TP
+.BR memrchr ()
+glibc 2.2.
+.TP
+.BR rawmemchr ()
+glibc 2.1.
+.SH SEE ALSO
+.BR bstring (3),
+.BR ffs (3),
+.BR memmem (3),
+.BR strchr (3),
+.BR strpbrk (3),
+.BR strrchr (3),
+.BR strsep (3),
+.BR strspn (3),
+.BR strstr (3),
+.BR wmemchr (3)
diff --git a/man/man3/memcmp.3 b/man/man3/memcmp.3
new file mode 100644
index 000000000..206ddad72
--- /dev/null
+++ b/man/man3/memcmp.3
@@ -0,0 +1,91 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:55:27 1993 by Rik Faith (faith@cs.unc.edu)
+.TH memcmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memcmp \- compare memory areas
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "int memcmp(const void " s1 [. n "], const void " s2 [. n "], size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR memcmp ()
+function compares the first \fIn\fP bytes (each interpreted as
+.IR "unsigned char" )
+of the memory areas \fIs1\fP and \fIs2\fP.
+.SH RETURN VALUE
+The
+.BR memcmp ()
+function returns an integer less than, equal to, or
+greater than zero if the first \fIn\fP bytes of \fIs1\fP is found,
+respectively, to be less than, to match, or be greater than the first
+\fIn\fP bytes of \fIs2\fP.
+.P
+For a nonzero return value, the sign is determined by the sign of
+the difference between the first pair of bytes (interpreted as
+.IR "unsigned char" )
+that differ in
+.I s1
+and
+.IR s2 .
+.P
+If
+.I n
+is zero, the return value is zero.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memcmp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH CAVEATS
+Do not use
+.BR memcmp ()
+to compare confidential data,
+such as cryptographic secrets,
+because the CPU time required for the comparison
+depends on the contents of the addresses compared,
+this function is subject to timing-based side-channel attacks.
+In such cases,
+a function that performs comparisons in deterministic time,
+depending only on
+.I n
+(the quantity of bytes compared)
+is required.
+Some operating systems provide such a function (e.g., NetBSD's
+.BR consttime_memequal ()),
+but no such function is specified in POSIX.
+On Linux, you may need to implement such a function yourself.
+.SH SEE ALSO
+.BR bstring (3),
+.BR strcasecmp (3),
+.BR strcmp (3),
+.BR strcoll (3),
+.BR strncasecmp (3),
+.BR strncmp (3),
+.BR wmemcmp (3)
diff --git a/man/man3/memcpy.3 b/man/man3/memcpy.3
new file mode 100644
index 000000000..c97f6701a
--- /dev/null
+++ b/man/man3/memcpy.3
@@ -0,0 +1,106 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:41:09 1993 by Rik Faith (faith@cs.unc.edu)
+.TH memcpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memcpy \- copy memory area
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "void *memcpy(void " dest "[restrict ." n "], const void " src "[restrict ." n ],
+.BI "             size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR memcpy ()
+function copies \fIn\fP bytes from memory area
+\fIsrc\fP to memory area \fIdest\fP.
+The memory areas must not overlap.
+Use
+.BR memmove (3)
+if the memory areas do overlap.
+.SH RETURN VALUE
+The
+.BR memcpy ()
+function returns a pointer to \fIdest\fP.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memcpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH CAVEATS
+Failure to observe the requirement that the memory areas
+do not overlap has been the source of significant bugs.
+(POSIX and the C standards are explicit that employing
+.BR memcpy ()
+with overlapping areas produces undefined behavior.)
+Most notably, in glibc 2.13
+.\" glibc commit 6fb8cbcb58a29fff73eb2101b34caa19a7f88eba
+a performance optimization of
+.BR memcpy ()
+on some platforms (including x86-64) included changing the order
+.\" From forward copying to backward copying
+in which bytes were copied from
+.I src
+to
+.IR dest .
+.P
+This change revealed breakages in a number of applications that performed
+copying with overlapping areas.
+.\" Adobe Flash player was the highest profile example:
+.\"   https://bugzilla.redhat.com/show_bug.cgi?id=638477
+.\"   Reported: 2010-09-29 02:35 EDT by JCHuynh
+.\"   Bug 638477 - Strange sound on mp3 flash website
+.\"
+.\"   https://sourceware.org/bugzilla/show_bug.cgi?id=12518
+.\"   Bug 12518 - memcpy acts randomly (and differently) with overlapping areas
+.\"   Reported:       2011-02-25 02:26 UTC by Linus Torvalds
+.\"
+Under the previous implementation,
+the order in which the bytes were copied had fortuitously hidden the bug,
+which was revealed when the copying order was reversed.
+In glibc 2.14,
+.\" glibc commit 0354e355014b7bfda32622e0255399d859862fcd
+a versioned symbol was added so that old binaries
+(i.e., those linked against glibc versions earlier than 2.14)
+employed a
+.BR memcpy ()
+implementation that safely handles the overlapping buffers case
+(by providing an "older"
+.BR memcpy ()
+implementation that was aliased to
+.BR memmove (3)).
+.SH SEE ALSO
+.BR bcopy (3),
+.BR bstring (3),
+.BR memccpy (3),
+.BR memmove (3),
+.BR mempcpy (3),
+.BR strcpy (3),
+.BR strncpy (3),
+.BR wmemcpy (3)
diff --git a/man/man3/memfrob.3 b/man/man3/memfrob.3
new file mode 100644
index 000000000..319717707
--- /dev/null
+++ b/man/man3/memfrob.3
@@ -0,0 +1,60 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:54:45 1993 by Rik Faith (faith@cs.unc.edu)
+.TH memfrob 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memfrob \- frobnicate (obfuscate) a memory area
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <string.h>
+.P
+.BI "void *memfrob(void " s [. n "], size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR memfrob ()
+function obfuscates the first \fIn\fP bytes of the
+memory area \fIs\fP by exclusive-ORing each character with the number
+42.
+The effect can be reversed by using
+.BR memfrob ()
+on the
+obfuscated memory area.
+.P
+Note that this function is not a proper encryption routine as the XOR
+constant is fixed, and is suitable only for hiding strings.
+.SH RETURN VALUE
+The
+.BR memfrob ()
+function returns a pointer to the obfuscated memory
+area.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memfrob ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR bstring (3),
+.BR strfry (3)
diff --git a/man/man3/memmem.3 b/man/man3/memmem.3
new file mode 100644
index 000000000..a807412b0
--- /dev/null
+++ b/man/man3/memmem.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:50:48 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Interchanged 'needle' and 'haystack'; added history, aeb, 980113.
+.TH memmem 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memmem \- locate a substring
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <string.h>
+.P
+.BI "void *memmem(const void " haystack [. haystacklen "], size_t " haystacklen ,
+.BI "             const void " needle [. needlelen "], size_t " needlelen  );
+.fi
+.SH DESCRIPTION
+The
+.BR memmem ()
+function finds the start of the first occurrence
+of the substring
+.I needle
+of length
+.I needlelen
+in the memory
+area
+.I haystack
+of length
+.IR haystacklen .
+.SH RETURN VALUE
+The
+.BR memmem ()
+function returns a pointer to the beginning of the
+substring, or NULL if the substring is not found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memmem ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+musl libc 0.9.7;
+FreeBSD 6.0, OpenBSD 5.4, NetBSD, Illumos.
+.SH BUGS
+.\" This function was broken in Linux libraries up to and including libc 5.0.9;
+.\" there the
+.\" .IR needle
+.\" and
+.\" .I haystack
+.\" arguments were interchanged,
+.\" and a pointer to the end of the first occurrence of
+.\" .I needle
+.\" was returned.
+.\"
+.\" Both old and new libc's have the bug that if
+.\" .I needle
+.\" is empty,
+.\" .I haystack\-1
+.\" (instead of
+.\" .IR haystack )
+.\" is returned.
+In glibc 2.0, if
+.I needle
+is empty,
+.BR memmem ()
+returns a pointer to the last byte of
+.IR haystack .
+This is fixed in glibc 2.1.
+.SH SEE ALSO
+.BR bstring (3),
+.BR strstr (3)
diff --git a/man/man3/memmove.3 b/man/man3/memmove.3
new file mode 100644
index 000000000..e68c54547
--- /dev/null
+++ b/man/man3/memmove.3
@@ -0,0 +1,71 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:49:59 1993 by Rik Faith (faith@cs.unc.edu)
+.TH memmove 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memmove \- copy memory area
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "void *memmove(void " dest [. n "], const void " src [. n "], size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR memmove ()
+function copies
+.I n
+bytes from memory area
+.I src
+to memory area
+.IR dest .
+The memory areas may overlap: copying takes place as though
+the bytes in
+.I src
+are first copied into a temporary array that does not overlap
+.I src
+or
+.IR dest ,
+and the bytes are then copied from the temporary array to
+.IR dest .
+.SH RETURN VALUE
+The
+.BR memmove ()
+function returns a pointer to
+.IR dest .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memmove ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR bcopy (3),
+.BR bstring (3),
+.BR memccpy (3),
+.BR memcpy (3),
+.BR strcpy (3),
+.BR strncpy (3),
+.BR wmemmove (3)
diff --git a/man/man3/mempcpy.3 b/man/man3/mempcpy.3
new file mode 100644
index 000000000..e20517dfd
--- /dev/null
+++ b/man/man3/mempcpy.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Heavily based on glibc infopages, copyright Free Software Foundation
+.\"
+.\" aeb, 2003, polished a little
+.TH mempcpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mempcpy, wmempcpy  \- copy memory area
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <string.h>
+.P
+.BI "void *mempcpy(void " dest "[restrict ." n "], const void " src "[restrict ." n ],
+.BI "              size_t " n );
+.P
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wmempcpy(wchar_t " dest "[restrict ." n ],
+.BI "              const wchar_t " src "[restrict ." n ],
+.BI "              size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR mempcpy ()
+function is nearly identical to the
+.BR memcpy (3)
+function.
+It copies
+.I n
+bytes from the object beginning at
+.I src
+into the object pointed to by
+.IR dest .
+But instead of returning the value of
+.I dest
+it returns a pointer to the byte following the last written byte.
+.P
+This function is useful in situations where a number of objects
+shall be copied to consecutive memory positions.
+.P
+The
+.BR wmempcpy ()
+function is identical but takes
+.I wchar_t
+type arguments and copies
+.I n
+wide characters.
+.SH RETURN VALUE
+.I dest
++
+.IR n .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mempcpy (),
+.BR wmempcpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.SH EXAMPLES
+.EX
+void *
+combine(void *o1, size_t s1, void *o2, size_t s2)
+{
+    void *result = malloc(s1 + s2);
+    if (result != NULL)
+        mempcpy(mempcpy(result, o1, s1), o2, s2);
+    return result;
+}
+.EE
+.SH SEE ALSO
+.BR memccpy (3),
+.BR memcpy (3),
+.BR memmove (3),
+.BR wmemcpy (3)
diff --git a/man/man3/memrchr.3 b/man/man3/memrchr.3
new file mode 100644
index 000000000..b62c8f10a
--- /dev/null
+++ b/man/man3/memrchr.3
@@ -0,0 +1 @@
+.so man3/memchr.3
diff --git a/man/man3/memset.3 b/man/man3/memset.3
new file mode 100644
index 000000000..1ac3ba3b6
--- /dev/null
+++ b/man/man3/memset.3
@@ -0,0 +1,60 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:49:23 1993 by Rik Faith (faith@cs.unc.edu)
+.TH memset 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+memset \- fill memory with a constant byte
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "void *memset(void " s [. n "], int " c ", size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR memset ()
+function fills the first
+.I n
+bytes of the
+memory area pointed to by
+.I s
+with the constant byte
+.IR c .
+.SH RETURN VALUE
+The
+.BR memset ()
+function returns a pointer to the memory area
+.IR s .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR memset ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR bstring (3),
+.BR bzero (3),
+.BR swab (3),
+.BR wmemset (3)
diff --git a/man/man3/minor.3 b/man/man3/minor.3
new file mode 100644
index 000000000..eabbdd013
--- /dev/null
+++ b/man/man3/minor.3
@@ -0,0 +1 @@
+.so man3/makedev.3
diff --git a/man/man3/mkdtemp.3 b/man/man3/mkdtemp.3
new file mode 100644
index 000000000..c2a4f5a0a
--- /dev/null
+++ b/man/man3/mkdtemp.3
@@ -0,0 +1,87 @@
+'\" t
+.\" Copyright 2001 John Levon <moz@compsoc.man.ac.uk>
+.\" Based on mkstemp(3), Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and GNU libc documentation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH mkdtemp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mkdtemp \- create a unique temporary directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "char *mkdtemp(char *" template );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mkdtemp ():
+.nf
+    /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc 2.19 and earlier: */ _BSD_SOURCE
+        || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200809L
+.fi
+.SH DESCRIPTION
+The
+.BR mkdtemp ()
+function generates a uniquely named temporary
+directory from \fItemplate\fP.
+The last six characters of \fItemplate\fP
+must be XXXXXX and these are replaced with a string that makes the
+directory name unique.
+The directory is then created with
+permissions 0700.
+Since it will be modified,
+.I template
+must not be a string constant, but should be declared as a character array.
+.SH RETURN VALUE
+The
+.BR mkdtemp ()
+function returns a pointer to the modified template
+string on success, and NULL on failure, in which case
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The last six characters of \fItemplate\fP were not XXXXXX.
+Now \fItemplate\fP is unchanged.
+.P
+Also see
+.BR mkdir (2)
+for other possible values for \fIerrno\fP.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mkdtemp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.91.
+NetBSD 1.4.
+POSIX.1-2008.
+.SH SEE ALSO
+.BR mktemp (1),
+.BR mkdir (2),
+.BR mkstemp (3),
+.BR mktemp (3),
+.BR tempnam (3),
+.BR tmpfile (3),
+.BR tmpnam (3)
diff --git a/man/man3/mkfifo.3 b/man/man3/mkfifo.3
new file mode 100644
index 000000000..f57474ba1
--- /dev/null
+++ b/man/man3/mkfifo.3
@@ -0,0 +1,201 @@
+'\" t
+.\" This manpage is Copyright (C) 1995 James R. Van Zandt <jrv@vanzandt.mv.com>
+.\" and Copyright (C) 2006, 2014 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" changed section from 2 to 3, aeb, 950919
+.\"
+.TH mkfifo 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mkfifo, mkfifoat \- make a FIFO special file (a named pipe)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <sys/stat.h>
+.P
+.BI "int mkfifo(const char *" pathname ", mode_t " mode );
+.P
+.BR "#include <fcntl.h>           " "/* Definition of AT_* constants */"
+.B #include <sys/stat.h>
+.P
+.BI "int mkfifoat(int " dirfd ", const char *" pathname ", mode_t " mode );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mkfifoat ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _ATFILE_SOURCE
+.fi
+.SH DESCRIPTION
+.BR mkfifo ()
+makes a FIFO special file with name \fIpathname\fP.
+\fImode\fP specifies the FIFO's permissions.
+It is modified by the
+process's \fBumask\fP in the usual way: the permissions of the created
+file are \fB(\fP\fImode\fP\fB & \[ti]umask)\fP.
+.P
+A FIFO special file is similar to a pipe, except that it is created
+in a different way.
+Instead of being an anonymous communications
+channel, a FIFO special file is entered into the filesystem by
+calling
+.BR mkfifo ().
+.P
+Once you have created a FIFO special file in this way, any process can
+open it for reading or writing, in the same way as an ordinary file.
+However, it has to be open at both ends simultaneously before you can
+proceed to do any input or output operations on it.
+Opening a FIFO for reading normally blocks until some
+other process opens the same FIFO for writing, and vice versa.
+See
+.BR fifo (7)
+for nonblocking handling of FIFO special files.
+.SS mkfifoat()
+The
+.BR mkfifoat ()
+function operates in exactly the same way as
+.BR mkfifo (),
+except for the differences described here.
+.P
+If the pathname given in
+.I pathname
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR mkfifo ()
+for a relative pathname).
+.P
+If
+.I pathname
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I pathname
+is interpreted relative to the current working
+directory of the calling process (like
+.BR mkfifo ()).
+.P
+If
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR mkfifoat ().
+.SH RETURN VALUE
+On success
+.BR mkfifo ()
+and
+.BR mkfifoat ()
+return 0.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+One of the directories in \fIpathname\fP did not allow search
+(execute) permission.
+.TP
+.B EBADF
+.RB ( mkfifoat ())
+.I pathname
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B EDQUOT
+The user's quota of disk blocks or inodes on the filesystem has been
+exhausted.
+.TP
+.B EEXIST
+\fIpathname\fP already exists.
+This includes the case where
+.I pathname
+is a symbolic link, dangling or not.
+.TP
+.B ENAMETOOLONG
+Either the total length of \fIpathname\fP is greater than
+\fBPATH_MAX\fP, or an individual filename component has a length
+greater than \fBNAME_MAX\fP.
+In the GNU system, there is no imposed
+limit on overall filename length, but some filesystems may place
+limits on the length of a component.
+.TP
+.B ENOENT
+A directory component in \fIpathname\fP does not exist or is a
+dangling symbolic link.
+.TP
+.B ENOSPC
+The directory or filesystem has no room for the new file.
+.TP
+.B ENOTDIR
+A component used as a directory in \fIpathname\fP is not, in fact, a
+directory.
+.TP
+.B ENOTDIR
+.RB ( mkfifoat ())
+.I pathname
+is a relative pathname and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.TP
+.B EROFS
+\fIpathname\fP refers to a read-only filesystem.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mkfifo (),
+.BR mkfifoat ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+It is implemented using
+.BR mknodat (2).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR mkfifo ()
+POSIX.1-2001.
+.TP
+.BR mkfifoat ()
+glibc 2.4.
+POSIX.1-2008.
+.SH SEE ALSO
+.BR mkfifo (1),
+.BR close (2),
+.BR open (2),
+.BR read (2),
+.BR stat (2),
+.BR umask (2),
+.BR write (2),
+.BR fifo (7)
diff --git a/man/man3/mkfifoat.3 b/man/man3/mkfifoat.3
new file mode 100644
index 000000000..25f4896f6
--- /dev/null
+++ b/man/man3/mkfifoat.3
@@ -0,0 +1 @@
+.so man3/mkfifo.3
diff --git a/man/man3/mkostemp.3 b/man/man3/mkostemp.3
new file mode 100644
index 000000000..08cc2dead
--- /dev/null
+++ b/man/man3/mkostemp.3
@@ -0,0 +1 @@
+.so man3/mkstemp.3
diff --git a/man/man3/mkostemps.3 b/man/man3/mkostemps.3
new file mode 100644
index 000000000..08cc2dead
--- /dev/null
+++ b/man/man3/mkostemps.3
@@ -0,0 +1 @@
+.so man3/mkstemp.3
diff --git a/man/man3/mkstemp.3 b/man/man3/mkstemp.3
new file mode 100644
index 000000000..c85dbd692
--- /dev/null
+++ b/man/man3/mkstemp.3
@@ -0,0 +1,247 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (C) 2008, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:48:48 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 980310, aeb
+.\" Modified 990328, aeb
+.\" 2008-06-19, mtk, Added mkostemp(); various other changes
+.\"
+.TH mkstemp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mkstemp, mkostemp, mkstemps, mkostemps \- create a unique temporary file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int mkstemp(char *" template );
+.BI "int mkostemp(char *" template ", int " flags );
+.BI "int mkstemps(char *" template ", int " suffixlen );
+.BI "int mkostemps(char *" template ", int " suffixlen ", int " flags );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mkstemp ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.12: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.P
+.BR mkostemp ():
+.nf
+    _GNU_SOURCE
+.fi
+.P
+.BR mkstemps ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.P
+.BR mkostemps ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR mkstemp ()
+function generates a unique temporary filename from
+.IR template ,
+creates and opens the file,
+and returns an open file descriptor for the file.
+.P
+The last six characters of
+.I template
+must be "XXXXXX" and these are replaced with a string that makes the
+filename unique.
+Since it will be modified,
+.I template
+must not be a string constant, but should be declared as a character array.
+.P
+The file is created with
+permissions 0600, that is, read plus write for owner only.
+The returned file descriptor provides both read and write access to the file.
+The file is opened with the
+.BR open (2)
+.B O_EXCL
+flag, guaranteeing that the caller is the process that creates the file.
+.P
+The
+.BR mkostemp ()
+function is like
+.BR mkstemp (),
+with the difference that the following bits\[em]with the same meaning as for
+.BR open (2)\[em]may
+be specified in
+.IR flags :
+.BR O_APPEND ,
+.BR O_CLOEXEC ,
+and
+.BR O_SYNC .
+Note that when creating the file,
+.BR mkostemp ()
+includes the values
+.BR O_RDWR ,
+.BR O_CREAT ,
+and
+.B O_EXCL
+in the
+.I flags
+argument given to
+.BR open (2);
+including these values in the
+.I flags
+argument given to
+.BR mkostemp ()
+is unnecessary, and produces errors on some
+.\" Reportedly, FreeBSD
+systems.
+.P
+The
+.BR mkstemps ()
+function is like
+.BR mkstemp (),
+except that the string in
+.I template
+contains a suffix of
+.I suffixlen
+characters.
+Thus,
+.I template
+is of the form
+.IR "prefixXXXXXXsuffix" ,
+and the string XXXXXX is modified as for
+.BR mkstemp ().
+.P
+The
+.BR mkostemps ()
+function is to
+.BR mkstemps ()
+as
+.BR mkostemp ()
+is to
+.BR mkstemp ().
+.SH RETURN VALUE
+On success, these functions return the file descriptor
+of the temporary file.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EEXIST
+Could not create a unique temporary filename.
+Now the contents of \fItemplate\fP are undefined.
+.TP
+.B EINVAL
+For
+.BR mkstemp ()
+and
+.BR mkostemp ():
+The last six characters of \fItemplate\fP were not XXXXXX;
+now \fItemplate\fP is unchanged.
+.IP
+For
+.BR mkstemps ()
+and
+.BR mkostemps ():
+.I template
+is less than
+.I "(6 + suffixlen)"
+characters long, or the last 6 characters before the suffix in
+.I template
+were not XXXXXX.
+.P
+These functions may also fail with any of the errors described for
+.BR open (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mkstemp (),
+.BR mkostemp (),
+.BR mkstemps (),
+.BR mkostemps ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR mkstemp ()
+POSIX.1-2001.
+.TP
+.BR mkstemps ()
+BSD.
+.\" mkstemps() appears to be at least on the BSDs, Mac OS X, Solaris,
+.\" and Tru64.
+.TP
+.BR mkostemp ()
+.TQ
+.BR mkostemps ()
+GNU.
+.SH HISTORY
+.TP
+.BR mkstemp ()
+4.3BSD, POSIX.1-2001.
+.TP
+.BR mkstemps ()
+glibc 2.11.
+BSD, Mac OS X, Solaris, Tru64.
+.TP
+.BR mkostemp ()
+glibc 2.7.
+.TP
+.BR mkostemps ()
+glibc 2.11.
+.P
+In glibc versions 2.06 and earlier, the file is created with permissions 0666,
+that is, read and write for all users.
+This old behavior may be
+a security risk, especially since other UNIX flavors use 0600,
+and somebody might overlook this detail when porting programs.
+POSIX.1-2008 adds a requirement that the file be created with mode 0600.
+.P
+More generally, the POSIX specification of
+.BR mkstemp ()
+does not say anything
+about file modes, so the application should make sure its
+file mode creation mask (see
+.BR umask (2))
+is set appropriately before calling
+.BR mkstemp ()
+(and
+.BR mkostemp ()).
+.\"
+.\" The prototype for
+.\" .BR mkstemp ()
+.\" is in
+.\" .I <unistd.h>
+.\" for libc4, libc5, glibc1; glibc2 follows POSIX.1 and has the prototype in
+.\" .IR <stdlib.h> .
+.SH SEE ALSO
+.BR mkdtemp (3),
+.BR mktemp (3),
+.BR tempnam (3),
+.BR tmpfile (3),
+.BR tmpnam (3)
diff --git a/man/man3/mkstemps.3 b/man/man3/mkstemps.3
new file mode 100644
index 000000000..08cc2dead
--- /dev/null
+++ b/man/man3/mkstemps.3
@@ -0,0 +1 @@
+.so man3/mkstemp.3
diff --git a/man/man3/mktemp.3 b/man/man3/mktemp.3
new file mode 100644
index 000000000..181325b98
--- /dev/null
+++ b/man/man3/mktemp.3
@@ -0,0 +1,118 @@
+'\" t
+.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:48:06 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Jun 23 01:26:34 1995 by Andries Brouwer (aeb@cwi.nl)
+.\" (prompted by Scott Burkett <scottb@IntNet.net>)
+.\" Modified Sun Mar 28 23:44:38 1999 by Andries Brouwer (aeb@cwi.nl)
+.\"
+.TH mktemp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mktemp \- make a unique temporary filename
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "char *mktemp(char *" template );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mktemp ():
+.nf
+    Since glibc 2.12:
+        (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200112L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+    Before glibc 2.12:
+        _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+.IR "Never use this function" ;
+see BUGS.
+.P
+The
+.BR mktemp ()
+function generates a unique temporary filename
+from \fItemplate\fP.
+The last six characters of \fItemplate\fP must
+be XXXXXX and these are replaced with a string that makes the
+filename unique.
+Since it will be modified,
+.I template
+must not be a string constant, but should be declared as a character array.
+.SH RETURN VALUE
+The
+.BR mktemp ()
+function always returns \fItemplate\fP.
+If a unique name was created, the last six bytes of \fItemplate\fP will
+have been modified in such a way that the resulting name is unique
+(i.e., does not exist already)
+If a unique name could not be created,
+\fItemplate\fP is made an empty string, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The last six characters of \fItemplate\fP were not XXXXXX.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mktemp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD, POSIX.1-2001.
+Removed in POSIX.1-2008.
+.\" .SH NOTES
+.\" The prototype is in
+.\" .I <unistd.h>
+.\" for libc4, libc5, glibc1; glibc2 follows the Single UNIX Specification
+.\" and has the prototype in
+.\" .IR <stdlib.h> .
+.SH BUGS
+Never use
+.BR mktemp ().
+Some implementations follow 4.3BSD
+and replace XXXXXX by the current process ID and a single letter,
+so that at most 26 different names can be returned.
+Since on the one hand the names are easy to guess, and on the other
+hand there is a race between testing whether the name exists and
+opening the file, every use of
+.BR mktemp ()
+is a security risk.
+The race is avoided by
+.BR mkstemp (3)
+and
+.BR mkdtemp (3).
+.SH SEE ALSO
+.BR mktemp (1),
+.BR mkdtemp (3),
+.BR mkstemp (3),
+.BR tempnam (3),
+.BR tmpfile (3),
+.BR tmpnam (3)
diff --git a/man/man3/mktime.3 b/man/man3/mktime.3
new file mode 100644
index 000000000..84a3baa92
--- /dev/null
+++ b/man/man3/mktime.3
@@ -0,0 +1 @@
+.so man3/ctime.3
diff --git a/man/man3/mmap64.3 b/man/man3/mmap64.3
new file mode 100644
index 000000000..8902d1b35
--- /dev/null
+++ b/man/man3/mmap64.3
@@ -0,0 +1 @@
+.so man2/mmap.2
diff --git a/man/man3/modf.3 b/man/man3/modf.3
new file mode 100644
index 000000000..333f2f859
--- /dev/null
+++ b/man/man3/modf.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH modf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+modf, modff, modfl \- extract signed integral and fractional values from
+floating-point number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double modf(double " x ", double *" iptr );
+.BI "float modff(float " x ", float *" iptr );
+.BI "long double modfl(long double " x ", long double *" iptr );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR modff (),
+.BR modfl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions break the argument
+.I x
+into an integral
+part and a fractional part, each of which has the same sign as
+.IR x .
+The integral part is stored in the location pointed to by
+.IR iptr .
+.SH RETURN VALUE
+These functions return the fractional part of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned, and
+.I *iptr
+is set to a NaN.
+.P
+If
+.I x
+is positive infinity (negative infinity), +0 (\-0) is returned, and
+.I *iptr
+is set to positive infinity (negative infinity).
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR modf (),
+.BR modff (),
+.BR modfl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR frexp (3),
+.BR ldexp (3)
diff --git a/man/man3/modff.3 b/man/man3/modff.3
new file mode 100644
index 000000000..84af2e33e
--- /dev/null
+++ b/man/man3/modff.3
@@ -0,0 +1 @@
+.so man3/modf.3
diff --git a/man/man3/modfl.3 b/man/man3/modfl.3
new file mode 100644
index 000000000..84af2e33e
--- /dev/null
+++ b/man/man3/modfl.3
@@ -0,0 +1 @@
+.so man3/modf.3
diff --git a/man/man3/mpool.3 b/man/man3/mpool.3
new file mode 100644
index 000000000..63b24ff2b
--- /dev/null
+++ b/man/man3/mpool.3
@@ -0,0 +1,205 @@
+.\" Copyright (c) 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	@(#)mpool.3	8.1 (Berkeley) 6/4/93
+.\"
+.TH mpool 3 (date) "Linux man-pages (unreleased)"
+.UC 7
+.SH NAME
+mpool \- shared memory buffer pool
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <db.h>
+.B #include <mpool.h>
+.P
+.BI "MPOOL *mpool_open(DBT *" key ", int " fd ", pgno_t " pagesize \
+", pgno_t " maxcache );
+.P
+.BI "void mpool_filter(MPOOL *" mp ", void (*pgin)(void *, pgno_t, void *),"
+.BI "                  void (*" pgout ")(void *, pgno_t, void *),"
+.BI "                  void *" pgcookie );
+.P
+.BI "void *mpool_new(MPOOL *" mp ", pgno_t *" pgnoaddr );
+.BI "void *mpool_get(MPOOL *" mp ", pgno_t " pgno ", unsigned int " flags );
+.BI "int mpool_put(MPOOL *" mp ", void *" pgaddr ", unsigned int " flags );
+.P
+.BI "int mpool_sync(MPOOL *" mp );
+.BI "int mpool_close(MPOOL *" mp );
+.fi
+.SH DESCRIPTION
+.IR "Note well" :
+This page documents interfaces provided up until glibc 2.1.
+Since glibc 2.2, glibc no longer provides these interfaces.
+Probably, you are looking for the APIs provided by the
+.I libdb
+library instead.
+.P
+.I Mpool
+is the library interface intended to provide page oriented buffer management
+of files.
+The buffers may be shared between processes.
+.P
+The function
+.BR mpool_open ()
+initializes a memory pool.
+The
+.I key
+argument is the byte string used to negotiate between multiple
+processes wishing to share buffers.
+If the file buffers are mapped in shared memory, all processes using
+the same key will share the buffers.
+If
+.I key
+is NULL, the buffers are mapped into private memory.
+The
+.I fd
+argument is a file descriptor for the underlying file, which must be seekable.
+If
+.I key
+is non-NULL and matches a file already being mapped, the
+.I fd
+argument is ignored.
+.P
+The
+.I pagesize
+argument is the size, in bytes, of the pages into which the file is broken up.
+The
+.I maxcache
+argument is the maximum number of pages from the underlying file to cache
+at any one time.
+This value is not relative to the number of processes which share a file's
+buffers, but will be the largest value specified by any of the processes
+sharing the file.
+.P
+The
+.BR mpool_filter ()
+function is intended to make transparent input and output processing of the
+pages possible.
+If the
+.I pgin
+function is specified, it is called each time a buffer is read into the memory
+pool from the backing file.
+If the
+.I pgout
+function is specified, it is called each time a buffer is written into the
+backing file.
+Both functions are called with the
+.I pgcookie
+pointer, the page number and a pointer to the page to being read or written.
+.P
+The function
+.BR mpool_new ()
+takes an
+.I MPOOL
+pointer and an address as arguments.
+If a new page can be allocated, a pointer to the page is returned and
+the page number is stored into the
+.I pgnoaddr
+address.
+Otherwise, NULL is returned and
+.I errno
+is set.
+.P
+The function
+.BR mpool_get ()
+takes an
+.I MPOOL
+pointer and a page number as arguments.
+If the page exists, a pointer to the page is returned.
+Otherwise, NULL is returned and
+.I errno
+is set.
+The
+.I flags
+argument is not currently used.
+.P
+The function
+.BR mpool_put ()
+unpins the page referenced by
+.IR pgaddr .
+.I pgaddr
+must be an address previously returned by
+.BR mpool_get ()
+or
+.BR mpool_new ().
+The flag value is specified by ORing
+any of the following values:
+.TP
+.B MPOOL_DIRTY
+The page has been modified and needs to be written to the backing file.
+.P
+.BR mpool_put ()
+returns 0 on success and \-1 if an error occurs.
+.P
+The function
+.BR mpool_sync ()
+writes all modified pages associated with the
+.I MPOOL
+pointer to the
+backing file.
+.BR mpool_sync ()
+returns 0 on success and \-1 if an error occurs.
+.P
+The
+.BR mpool_close ()
+function free's up any allocated memory associated with the memory pool
+cookie.
+Modified pages are
+.B not
+written to the backing file.
+.BR mpool_close ()
+returns 0 on success and \-1 if an error occurs.
+.SH ERRORS
+The
+.BR mpool_open ()
+function may fail and set
+.I errno
+for any of the errors specified for the library routine
+.BR malloc (3).
+.P
+The
+.BR mpool_get ()
+function may fail and set
+.I errno
+for the following:
+.TP 15
+.B EINVAL
+The requested record doesn't exist.
+.P
+The
+.BR mpool_new ()
+and
+.BR mpool_get ()
+functions may fail and set
+.I errno
+for any of the errors specified for the library routines
+.BR read (2),
+.BR write (2),
+and
+.BR malloc (3).
+.P
+The
+.BR mpool_sync ()
+function may fail and set
+.I errno
+for any of the errors specified for the library routine
+.BR write (2).
+.P
+The
+.BR mpool_close ()
+function may fail and set
+.I errno
+for any of the errors specified for the library routine
+.BR free (3).
+.SH STANDARDS
+BSD.
+.SH SEE ALSO
+.BR btree (3),
+.BR dbopen (3),
+.BR hash (3),
+.BR recno (3)
diff --git a/man/man3/mprobe.3 b/man/man3/mprobe.3
new file mode 100644
index 000000000..4baeaf2a5
--- /dev/null
+++ b/man/man3/mprobe.3
@@ -0,0 +1 @@
+.so man3/mcheck.3
diff --git a/man/man3/mq_close.3 b/man/man3/mq_close.3
new file mode 100644
index 000000000..5810bb36f
--- /dev/null
+++ b/man/man3/mq_close.3
@@ -0,0 +1,70 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_close 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_close \- close a message queue descriptor
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <mqueue.h>
+.P
+.BI "int mq_close(mqd_t " mqdes );
+.fi
+.SH DESCRIPTION
+.BR mq_close ()
+closes the message queue descriptor
+.IR mqdes .
+.P
+If the calling process has attached a notification request (see
+.BR mq_notify (3))
+to this message queue via
+.IR mqdes ,
+then this request is removed,
+and another process can now attach a notification request.
+.SH RETURN VALUE
+On success
+.BR mq_close ()
+returns 0; on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The message queue descriptor specified in
+.I mqdes
+is invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mq_close ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+All open message queues are automatically closed on process termination,
+or upon
+.BR execve (2).
+.SH SEE ALSO
+.BR mq_getattr (3),
+.BR mq_notify (3),
+.BR mq_open (3),
+.BR mq_receive (3),
+.BR mq_send (3),
+.BR mq_unlink (3),
+.BR mq_overview (7)
diff --git a/man/man3/mq_getattr.3 b/man/man3/mq_getattr.3
new file mode 100644
index 000000000..3d11c308c
--- /dev/null
+++ b/man/man3/mq_getattr.3
@@ -0,0 +1,229 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_getattr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_getattr, mq_setattr \- get/set message queue attributes
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <mqueue.h>
+.P
+.BI "int mq_getattr(mqd_t " mqdes ", struct mq_attr *" attr );
+.BI "int mq_setattr(mqd_t " mqdes ", const struct mq_attr *restrict " newattr ,
+.BI "               struct mq_attr *restrict " oldattr );
+.fi
+.SH DESCRIPTION
+.BR mq_getattr ()
+and
+.BR mq_setattr ()
+respectively retrieve and modify attributes of the message queue
+referred to by the message queue descriptor
+.IR mqdes .
+.P
+.BR mq_getattr ()
+returns an
+.I mq_attr
+structure in the buffer pointed by
+.IR attr .
+This structure is defined as:
+.P
+.in +4n
+.EX
+struct mq_attr {
+    long mq_flags;       /* Flags: 0 or O_NONBLOCK */
+    long mq_maxmsg;      /* Max. # of messages on queue */
+    long mq_msgsize;     /* Max. message size (bytes) */
+    long mq_curmsgs;     /* # of messages currently in queue */
+};
+.EE
+.in
+.P
+The
+.I mq_flags
+field contains flags associated with the open message queue description.
+This field is initialized when the queue is created by
+.BR mq_open (3).
+The only flag that can appear in this field is
+.BR O_NONBLOCK .
+.P
+The
+.I mq_maxmsg
+and
+.I mq_msgsize
+fields are set when the message queue is created by
+.BR mq_open (3).
+The
+.I mq_maxmsg
+field is an upper limit on the number of messages
+that may be placed on the queue using
+.BR mq_send (3).
+The
+.I mq_msgsize
+field is an upper limit on the size of messages
+that may be placed on the queue.
+Both of these fields must have a value greater than zero.
+Two
+.I /proc
+files that place ceilings on the values for these fields are described in
+.BR mq_overview (7).
+.P
+The
+.I mq_curmsgs
+field returns the number of messages currently held in the queue.
+.P
+.BR mq_setattr ()
+sets message queue attributes using information supplied in the
+.I mq_attr
+structure pointed to by
+.IR newattr .
+The only attribute that can be modified is the setting of the
+.B O_NONBLOCK
+flag in
+.IR mq_flags .
+The other fields in
+.I newattr
+are ignored.
+If the
+.I oldattr
+field is not NULL,
+then the buffer that it points to is used to return an
+.I mq_attr
+structure that contains the same information that is returned by
+.BR mq_getattr ().
+.SH RETURN VALUE
+On success
+.BR mq_getattr ()
+and
+.BR mq_setattr ()
+return 0; on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The message queue descriptor specified in
+.I mqdes
+is invalid.
+.TP
+.B EINVAL
+.I newattr\->mq_flags
+contained set bits other than
+.BR O_NONBLOCK .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mq_getattr (),
+.BR mq_setattr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On Linux,
+.BR mq_getattr ()
+and
+.BR mq_setattr ()
+are library functions layered on top of the
+.BR mq_getsetattr (2)
+system call.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+The program below can be used to show the default
+.I mq_maxmsg
+and
+.I mq_msgsize
+values that are assigned to a message queue that is created with a call to
+.BR mq_open (3)
+in which the
+.I attr
+argument is NULL.
+Here is an example run of the program:
+.P
+.in +4n
+.EX
+$ \fB./a.out /testq\fP
+Maximum # of messages on queue:   10
+Maximum message size:             8192
+.EE
+.in
+.P
+Since Linux 3.5, the following
+.I /proc
+files (described in
+.BR mq_overview (7))
+can be used to control the defaults:
+.P
+.in +4n
+.EX
+$ \fBuname \-sr\fP
+Linux 3.8.0
+$ \fBcat /proc/sys/fs/mqueue/msg_default\fP
+10
+$ \fBcat /proc/sys/fs/mqueue/msgsize_default\fP
+8192
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (mq_getattr.c)
+.EX
+#include <fcntl.h>
+#include <mqueue.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+int
+main(int argc, char *argv[])
+{
+    mqd_t mqd;
+    struct mq_attr attr;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s mq\-name\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    mqd = mq_open(argv[1], O_CREAT | O_EXCL, 0600, NULL);
+    if (mqd == (mqd_t) \-1)
+        errExit("mq_open");
+\&
+    if (mq_getattr(mqd, &attr) == \-1)
+        errExit("mq_getattr");
+\&
+    printf("Maximum # of messages on queue:   %ld\en", attr.mq_maxmsg);
+    printf("Maximum message size:             %ld\en", attr.mq_msgsize);
+\&
+    if (mq_unlink(argv[1]) == \-1)
+        errExit("mq_unlink");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR mq_close (3),
+.BR mq_notify (3),
+.BR mq_open (3),
+.BR mq_receive (3),
+.BR mq_send (3),
+.BR mq_unlink (3),
+.BR mq_overview (7)
diff --git a/man/man3/mq_notify.3 b/man/man3/mq_notify.3
new file mode 100644
index 000000000..653e401c9
--- /dev/null
+++ b/man/man3/mq_notify.3
@@ -0,0 +1,273 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_notify 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_notify \- register for notification when a message is available
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <mqueue.h>
+.BR "#include <signal.h>           " "/* Definition of SIGEV_* constants */"
+.P
+.BI "int mq_notify(mqd_t " mqdes ", const struct sigevent *" sevp );
+.fi
+.SH DESCRIPTION
+.BR mq_notify ()
+allows the calling process to register or unregister for delivery of
+an asynchronous notification when a new message arrives on
+the empty message queue referred to by the message queue descriptor
+.IR mqdes .
+.P
+The
+.I sevp
+argument is a pointer to a
+.I sigevent
+structure.
+For the definition and general details of this structure, see
+.BR sigevent (3type).
+.P
+If
+.I sevp
+is a non-null pointer, then
+.BR mq_notify ()
+registers the calling process to receive message notification.
+The
+.I sigev_notify
+field of the
+.I sigevent
+structure to which
+.I sevp
+points specifies how notification is to be performed.
+This field has one of the following values:
+.TP
+.B SIGEV_NONE
+A "null" notification: the calling process is registered as the target
+for notification, but when a message arrives, no notification is sent.
+.\" When is SIGEV_NONE useful?
+.TP
+.B SIGEV_SIGNAL
+Notify the process by sending the signal specified in
+.IR sigev_signo .
+See
+.BR sigevent (3type)
+for general details.
+The
+.I si_code
+field of the
+.I siginfo_t
+structure will be set to
+.BR SI_MESGQ .
+In addition,
+.\" I don't know of other implementations that set
+.\" si_pid and si_uid -- MTK
+.I si_pid
+will be set to the PID of the process that sent the message, and
+.I si_uid
+will be set to the real user ID of the sending process.
+.TP
+.B SIGEV_THREAD
+Upon message delivery, invoke
+.I sigev_notify_function
+as if it were the start function of a new thread.
+See
+.BR sigevent (3type)
+for details.
+.P
+Only one process can be registered to receive notification
+from a message queue.
+.P
+If
+.I sevp
+is NULL, and the calling process is currently registered to receive
+notifications for this message queue, then the registration is removed;
+another process can then register to receive a message notification
+for this queue.
+.P
+Message notification occurs only when a new message arrives and
+the queue was previously empty.
+If the queue was not empty at the time
+.BR mq_notify ()
+was called, then a notification will occur only after
+the queue is emptied and a new message arrives.
+.P
+If another process or thread is waiting to read a message
+from an empty queue using
+.BR mq_receive (3),
+then any message notification registration is ignored:
+the message is delivered to the process or thread calling
+.BR mq_receive (3),
+and the message notification registration remains in effect.
+.P
+Notification occurs once: after a notification is delivered,
+the notification registration is removed,
+and another process can register for message notification.
+If the notified process wishes to receive the next notification,
+it can use
+.BR mq_notify ()
+to request a further notification.
+This should be done before emptying all unread messages from the queue.
+(Placing the queue in nonblocking mode is useful for emptying
+the queue of messages without blocking once it is empty.)
+.SH RETURN VALUE
+On success
+.BR mq_notify ()
+returns 0; on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The message queue descriptor specified in
+.I mqdes
+is invalid.
+.TP
+.B EBUSY
+Another process has already registered to receive notification
+for this message queue.
+.TP
+.B EINVAL
+.I sevp\->sigev_notify
+is not one of the permitted values; or
+.I sevp\->sigev_notify
+is
+.B SIGEV_SIGNAL
+and
+.I sevp\->sigev_signo
+is not a valid signal number.
+.TP
+.B ENOMEM
+Insufficient memory.
+.P
+POSIX.1-2008 says that an implementation
+.I may
+generate an
+.B EINVAL
+.\" Linux does not do this
+error if
+.I sevp
+is NULL, and the caller is not currently registered to receive
+notifications for the queue
+.IR mqdes .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mq_notify ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.SS C library/kernel differences
+In the glibc implementation, the
+.BR mq_notify ()
+library function is implemented on top of the system call of the same name.
+When
+.I sevp
+is NULL, or specifies a notification mechanism other than
+.BR SIGEV_THREAD ,
+the library function directly invokes the system call.
+For
+.BR SIGEV_THREAD ,
+much of the implementation resides within the library,
+rather than the kernel.
+(This is necessarily so,
+since the thread involved in handling the notification is one
+that must be managed by the C library POSIX threads implementation.)
+The implementation involves the use of a raw
+.BR netlink (7)
+socket and creates a new thread for each notification that is
+delivered to the process.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+The following program registers a notification request for the
+message queue named in its command-line argument.
+Notification is performed by creating a thread.
+The thread executes a function which reads one message from the
+queue and then terminates the process.
+.SS Program source
+.\" SRC BEGIN (mq_notify.c)
+.EX
+#include <mqueue.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define handle_error(msg) \e
+    do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static void                     /* Thread start function */
+tfunc(union sigval sv)
+{
+    struct mq_attr attr;
+    ssize_t nr;
+    void *buf;
+    mqd_t mqdes = *((mqd_t *) sv.sival_ptr);
+\&
+    /* Determine max. msg size; allocate buffer to receive msg */
+\&
+    if (mq_getattr(mqdes, &attr) == \-1)
+        handle_error("mq_getattr");
+    buf = malloc(attr.mq_msgsize);
+    if (buf == NULL)
+        handle_error("malloc");
+\&
+    nr = mq_receive(mqdes, buf, attr.mq_msgsize, NULL);
+    if (nr == \-1)
+        handle_error("mq_receive");
+\&
+    printf("Read %zd bytes from MQ\en", nr);
+    free(buf);
+    exit(EXIT_SUCCESS);         /* Terminate the process */
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    mqd_t mqdes;
+    struct sigevent sev;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <mq\-name>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    mqdes = mq_open(argv[1], O_RDONLY);
+    if (mqdes == (mqd_t) \-1)
+        handle_error("mq_open");
+\&
+    sev.sigev_notify = SIGEV_THREAD;
+    sev.sigev_notify_function = tfunc;
+    sev.sigev_notify_attributes = NULL;
+    sev.sigev_value.sival_ptr = &mqdes;   /* Arg. to thread func. */
+    if (mq_notify(mqdes, &sev) == \-1)
+        handle_error("mq_notify");
+\&
+    pause();    /* Process will be terminated by thread function */
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR mq_close (3),
+.BR mq_getattr (3),
+.BR mq_open (3),
+.BR mq_receive (3),
+.BR mq_send (3),
+.BR mq_unlink (3),
+.BR mq_overview (7),
+.BR sigevent (3type)
diff --git a/man/man3/mq_open.3 b/man/man3/mq_open.3
new file mode 100644
index 000000000..7343ea093
--- /dev/null
+++ b/man/man3/mq_open.3
@@ -0,0 +1,298 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_open 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_open \- open a message queue
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" "           /* For O_* constants */"
+.BR "#include <sys/stat.h>" "        /* For mode constants */"
+.B #include <mqueue.h>
+.P
+.BI "mqd_t mq_open(const char *" name ", int " oflag );
+.BI "mqd_t mq_open(const char *" name ", int " oflag ", mode_t " mode ,
+.BI "              struct mq_attr *" attr );
+.fi
+.SH DESCRIPTION
+.BR mq_open ()
+creates a new POSIX message queue or opens an existing queue.
+The queue is identified by
+.IR name .
+For details of the construction of
+.IR name ,
+see
+.BR mq_overview (7).
+.P
+The
+.I oflag
+argument specifies flags that control the operation of the call.
+(Definitions of the flags values can be obtained by including
+.IR <fcntl.h> .)
+Exactly one of the following must be specified in
+.IR oflag :
+.TP
+.B O_RDONLY
+Open the queue to receive messages only.
+.TP
+.B O_WRONLY
+Open the queue to send messages only.
+.TP
+.B O_RDWR
+Open the queue to both send and receive messages.
+.P
+Zero or more of the following flags can additionally be
+.IR OR ed
+in
+.IR oflag :
+.TP
+.BR O_CLOEXEC " (since Linux 2.6.26)"
+.\" commit 269f21344b23e552c21c9e2d7ca258479dcd7a0a
+Set the close-on-exec flag for the message queue descriptor.
+See
+.BR open (2)
+for a discussion of why this flag is useful.
+.TP
+.B O_CREAT
+Create the message queue if it does not exist.
+The owner (user ID) of the message queue is set to the effective
+user ID of the calling process.
+The group ownership (group ID) is set to the effective group ID
+of the calling process.
+.\" In reality the filesystem IDs are used on Linux.
+.TP
+.B O_EXCL
+If
+.B O_CREAT
+was specified in
+.IR oflag ,
+and a queue with the given
+.I name
+already exists, then fail with the error
+.BR EEXIST .
+.TP
+.B O_NONBLOCK
+Open the queue in nonblocking mode.
+In circumstances where
+.BR mq_receive (3)
+and
+.BR mq_send (3)
+would normally block, these functions instead fail with the error
+.BR EAGAIN .
+.P
+If
+.B O_CREAT
+is specified in
+.IR oflag ,
+then two additional arguments must be supplied.
+The
+.I mode
+argument specifies the permissions to be placed on the new queue,
+as for
+.BR open (2).
+(Symbolic definitions for the permissions bits can be obtained by including
+.IR <sys/stat.h> .)
+The permissions settings are masked against the process umask.
+.P
+The fields of the
+.I struct mq_attr
+pointed to
+.I attr
+specify the maximum number of messages and
+the maximum size of messages that the queue will allow.
+This structure is defined as follows:
+.P
+.in +4n
+.EX
+struct mq_attr {
+    long mq_flags;       /* Flags (ignored for mq_open()) */
+    long mq_maxmsg;      /* Max. # of messages on queue */
+    long mq_msgsize;     /* Max. message size (bytes) */
+    long mq_curmsgs;     /* # of messages currently in queue
+                            (ignored for mq_open()) */
+};
+.EE
+.in
+.P
+Only the
+.I mq_maxmsg
+and
+.I mq_msgsize
+fields are employed when calling
+.BR mq_open ();
+the values in the remaining fields are ignored.
+.P
+If
+.I attr
+is NULL, then the queue is created with implementation-defined
+default attributes.
+Since Linux 3.5, two
+.I /proc
+files can be used to control these defaults; see
+.BR mq_overview (7)
+for details.
+.SH RETURN VALUE
+On success,
+.BR mq_open ()
+returns a message queue descriptor for use by other
+message queue functions.
+On error,
+.BR mq_open ()
+returns
+.IR "(mqd_t)\ \-1",
+with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The queue exists, but the caller does not have permission to
+open it in the specified mode.
+.TP
+.B EACCES
+.I name
+contained more than one slash.
+.\" Note that this isn't consistent with the same case for sem_open()
+.TP
+.B EEXIST
+Both
+.B O_CREAT
+and
+.B O_EXCL
+were specified in
+.IR oflag ,
+but a queue with this
+.I name
+already exists.
+.TP
+.B EINVAL
+.\" glibc checks whether the name starts with a "/" and if not,
+.\" gives this error
+.I name
+doesn't follow the format in
+.BR mq_overview (7).
+.TP
+.B EINVAL
+.B O_CREAT
+was specified in
+.IR oflag ,
+and
+.I attr
+was not NULL, but
+.I attr\->mq_maxmsg
+or
+.I attr\->mq_msqsize
+was invalid.
+Both of these fields must be greater than zero.
+In a process that is unprivileged (does not have the
+.B CAP_SYS_RESOURCE
+capability),
+.I attr\->mq_maxmsg
+must be less than or equal to the
+.I msg_max
+limit, and
+.I attr\->mq_msgsize
+must be less than or equal to the
+.I msgsize_max
+limit.
+In addition, even in a privileged process,
+.I attr\->mq_maxmsg
+cannot exceed the
+.B HARD_MAX
+limit.
+(See
+.BR mq_overview (7)
+for details of these limits.)
+.TP
+.B EMFILE
+The per-process limit on the number of open file
+and message queue descriptors has been reached
+(see the description of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2)).
+.TP
+.B ENAMETOOLONG
+.I name
+was too long.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files
+and message queues has been reached.
+.TP
+.B ENOENT
+The
+.B O_CREAT
+flag was not specified in
+.IR oflag ,
+and no queue with this
+.I name
+exists.
+.TP
+.B ENOENT
+.I name
+was just "/" followed by no other characters.
+.\" Note that this isn't consistent with the same case for sem_open()
+.TP
+.B ENOMEM
+Insufficient memory.
+.TP
+.B ENOSPC
+Insufficient space for the creation of a new message queue.
+This probably occurred because the
+.I queues_max
+limit was encountered; see
+.BR mq_overview (7).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mq_open ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.SS C library/kernel differences
+The
+.BR mq_open ()
+library function is implemented on top of a system call of the same name.
+The library function performs the check that the
+.I name
+starts with a slash (/), giving the
+.B EINVAL
+error if it does not.
+The kernel system call expects
+.I name
+to contain no preceding slash,
+so the C library function passes
+.I name
+without the preceding slash (i.e.,
+.IR name+1 )
+to the system call.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH BUGS
+Before Linux 2.6.14,
+the process umask was not applied to the permissions specified in
+.IR mode .
+.SH SEE ALSO
+.BR mq_close (3),
+.BR mq_getattr (3),
+.BR mq_notify (3),
+.BR mq_receive (3),
+.BR mq_send (3),
+.BR mq_unlink (3),
+.BR mq_overview (7)
diff --git a/man/man3/mq_receive.3 b/man/man3/mq_receive.3
new file mode 100644
index 000000000..232c191df
--- /dev/null
+++ b/man/man3/mq_receive.3
@@ -0,0 +1,163 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_receive 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_receive, mq_timedreceive \- receive a message from a message queue
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <mqueue.h>
+.P
+.BI "ssize_t mq_receive(mqd_t " mqdes ", char " msg_ptr [. msg_len ],
+.BI "                   size_t " msg_len ", unsigned int *" msg_prio );
+.P
+.B #include <time.h>
+.B #include <mqueue.h>
+.P
+.BI "ssize_t mq_timedreceive(mqd_t " mqdes ", \
+char *restrict " msg_ptr [. msg_len ],
+.BI "                   size_t " msg_len ", unsigned int *restrict " msg_prio ,
+.BI "                   const struct timespec *restrict " abs_timeout );
+.fi
+.P
+.ad l
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mq_timedreceive ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.BR mq_receive ()
+removes the oldest message with the highest priority from
+the message queue referred to by the message queue descriptor
+.IR mqdes ,
+and places it in the buffer pointed to by
+.IR msg_ptr .
+The
+.I msg_len
+argument specifies the size of the buffer pointed to by
+.IR msg_ptr ;
+this must be greater than or equal to the
+.I mq_msgsize
+attribute of the queue (see
+.BR mq_getattr (3)).
+If
+.I msg_prio
+is not NULL, then the buffer to which it points is used
+to return the priority associated with the received message.
+.P
+If the queue is empty, then, by default,
+.BR mq_receive ()
+blocks until a message becomes available,
+or the call is interrupted by a signal handler.
+If the
+.B O_NONBLOCK
+flag is enabled for the message queue description,
+then the call instead fails immediately with the error
+.BR EAGAIN .
+.P
+.BR mq_timedreceive ()
+behaves just like
+.BR mq_receive (),
+except that if the queue is empty and the
+.B O_NONBLOCK
+flag is not enabled for the message queue description, then
+.I abs_timeout
+points to a structure which specifies how long the call will block.
+This value is an absolute timeout in seconds and nanoseconds
+since the Epoch, 1970-01-01 00:00:00 +0000 (UTC),
+specified in a
+.BR timespec (3)
+structure.
+.P
+If no message is available,
+and the timeout has already expired by the time of the call,
+.BR mq_timedreceive ()
+returns immediately.
+.SH RETURN VALUE
+On success,
+.BR mq_receive ()
+and
+.BR mq_timedreceive ()
+return the number of bytes in the received message;
+on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The queue was empty, and the
+.B O_NONBLOCK
+flag was set for the message queue description referred to by
+.IR mqdes .
+.TP
+.B EBADF
+The descriptor specified in
+.I mqdes
+was invalid or not opened for reading.
+.TP
+.B EINTR
+The call was interrupted by a signal handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+The call would have blocked, and
+.I abs_timeout
+was invalid, either because
+.I tv_sec
+was less than zero, or because
+.I tv_nsec
+was less than zero or greater than 1000 million.
+.TP
+.B EMSGSIZE
+.I msg_len
+was less than the
+.I mq_msgsize
+attribute of the message queue.
+.TP
+.B ETIMEDOUT
+The call timed out before a message could be transferred.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mq_receive (),
+.BR mq_timedreceive ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On Linux,
+.BR mq_timedreceive ()
+is a system call, and
+.BR mq_receive ()
+is a library function layered on top of that system call.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR mq_close (3),
+.BR mq_getattr (3),
+.BR mq_notify (3),
+.BR mq_open (3),
+.BR mq_send (3),
+.BR mq_unlink (3),
+.BR timespec (3),
+.BR mq_overview (7),
+.BR time (7)
diff --git a/man/man3/mq_send.3 b/man/man3/mq_send.3
new file mode 100644
index 000000000..2cc63825c
--- /dev/null
+++ b/man/man3/mq_send.3
@@ -0,0 +1,170 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_send 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_send, mq_timedsend \- send a message to a message queue
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <mqueue.h>
+.P
+.BI "int mq_send(mqd_t " mqdes ", const char " msg_ptr [. msg_len ],
+.BI "              size_t " msg_len ", unsigned int " msg_prio );
+.P
+.B #include <time.h>
+.B #include <mqueue.h>
+.P
+.BI "int mq_timedsend(mqd_t " mqdes ", const char " msg_ptr [. msg_len ],
+.BI "              size_t " msg_len ", unsigned int " msg_prio ,
+.BI "              const struct timespec *" abs_timeout );
+.fi
+.P
+.ad l
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR mq_timedsend ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.BR mq_send ()
+adds the message pointed to by
+.I msg_ptr
+to the message queue referred to by the message queue descriptor
+.IR mqdes .
+The
+.I msg_len
+argument specifies the length of the message pointed to by
+.IR msg_ptr ;
+this length must be less than or equal to the queue's
+.I mq_msgsize
+attribute.
+Zero-length messages are allowed.
+.P
+The
+.I msg_prio
+argument is a nonnegative integer that specifies the priority
+of this message.
+Messages are placed on the queue in decreasing order of priority,
+with newer messages of the same priority being placed after
+older messages with the same priority.
+See
+.BR mq_overview (7)
+for details on the range for the message priority.
+.P
+If the message queue is already full
+(i.e., the number of messages on the queue equals the queue's
+.I mq_maxmsg
+attribute), then, by default,
+.BR mq_send ()
+blocks until sufficient space becomes available to allow the message
+to be queued, or until the call is interrupted by a signal handler.
+If the
+.B O_NONBLOCK
+flag is enabled for the message queue description,
+then the call instead fails immediately with the error
+.BR EAGAIN .
+.P
+.BR mq_timedsend ()
+behaves just like
+.BR mq_send (),
+except that if the queue is full and the
+.B O_NONBLOCK
+flag is not enabled for the message queue description, then
+.I abs_timeout
+points to a structure which specifies how long the call will block.
+This value is an absolute timeout in seconds and nanoseconds
+since the Epoch, 1970-01-01 00:00:00 +0000 (UTC),
+specified in a
+.BR timespec (3)
+structure.
+.P
+If the message queue is full,
+and the timeout has already expired by the time of the call,
+.BR mq_timedsend ()
+returns immediately.
+.SH RETURN VALUE
+On success,
+.BR mq_send ()
+and
+.BR mq_timedsend ()
+return zero; on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The queue was full, and the
+.B O_NONBLOCK
+flag was set for the message queue description referred to by
+.IR mqdes .
+.TP
+.B EBADF
+The descriptor specified in
+.I mqdes
+was invalid or not opened for writing.
+.TP
+.B EINTR
+The call was interrupted by a signal handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+The call would have blocked, and
+.I abs_timeout
+was invalid, either because
+.I tv_sec
+was less than zero, or because
+.I tv_nsec
+was less than zero or greater than 1000 million.
+.TP
+.B EMSGSIZE
+.I msg_len
+was greater than the
+.I mq_msgsize
+attribute of the message queue.
+.TP
+.B ETIMEDOUT
+The call timed out before a message could be transferred.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mq_send (),
+.BR mq_timedsend ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On Linux,
+.BR mq_timedsend ()
+is a system call, and
+.BR mq_send ()
+is a library function layered on top of that system call.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR mq_close (3),
+.BR mq_getattr (3),
+.BR mq_notify (3),
+.BR mq_open (3),
+.BR mq_receive (3),
+.BR mq_unlink (3),
+.BR timespec (3),
+.BR mq_overview (7),
+.BR time (7)
diff --git a/man/man3/mq_setattr.3 b/man/man3/mq_setattr.3
new file mode 100644
index 000000000..a3818a208
--- /dev/null
+++ b/man/man3/mq_setattr.3
@@ -0,0 +1 @@
+.so man3/mq_getattr.3
diff --git a/man/man3/mq_timedreceive.3 b/man/man3/mq_timedreceive.3
new file mode 100644
index 000000000..9fed5f293
--- /dev/null
+++ b/man/man3/mq_timedreceive.3
@@ -0,0 +1 @@
+.so man3/mq_receive.3
diff --git a/man/man3/mq_timedsend.3 b/man/man3/mq_timedsend.3
new file mode 100644
index 000000000..28b1eff0a
--- /dev/null
+++ b/man/man3/mq_timedsend.3
@@ -0,0 +1 @@
+.so man3/mq_send.3
diff --git a/man/man3/mq_unlink.3 b/man/man3/mq_unlink.3
new file mode 100644
index 000000000..5457b55f4
--- /dev/null
+++ b/man/man3/mq_unlink.3
@@ -0,0 +1,68 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_unlink 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_unlink \- remove a message queue
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <mqueue.h>
+.P
+.BI "int mq_unlink(const char *" name );
+.fi
+.SH DESCRIPTION
+.BR mq_unlink ()
+removes the specified message queue
+.IR name .
+The message queue name is removed immediately.
+The queue itself is destroyed once any other processes that have
+the queue open close their descriptors referring to the queue.
+.SH RETURN VALUE
+On success
+.BR mq_unlink ()
+returns 0; on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The caller does not have permission to unlink this message queue.
+.TP
+.B ENAMETOOLONG
+.I name
+was too long.
+.TP
+.B ENOENT
+There is no message queue with the given
+.IR name .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mq_unlink ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR mq_close (3),
+.BR mq_getattr (3),
+.BR mq_notify (3),
+.BR mq_open (3),
+.BR mq_receive (3),
+.BR mq_send (3),
+.BR mq_overview (7)
diff --git a/man/man3/mrand48.3 b/man/man3/mrand48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/mrand48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/mrand48_r.3 b/man/man3/mrand48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/mrand48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/mtrace.3 b/man/man3/mtrace.3
new file mode 100644
index 000000000..3885f73af
--- /dev/null
+++ b/man/man3/mtrace.3
@@ -0,0 +1,180 @@
+'\" t
+.\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mtrace 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mtrace, muntrace \- malloc tracing
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <mcheck.h>"
+.P
+.B "void mtrace(void);"
+.B "void muntrace(void);"
+.fi
+.SH DESCRIPTION
+The
+.BR mtrace ()
+function installs hook functions for the memory-allocation functions
+.RB ( malloc (3),
+.BR realloc (3)
+.BR memalign (3),
+.BR free (3)).
+These hook functions record tracing information about memory allocation
+and deallocation.
+The tracing information can be used to discover memory leaks and
+attempts to free nonallocated memory in a program.
+.P
+The
+.BR muntrace ()
+function disables the hook functions installed by
+.BR mtrace (),
+so that tracing information is no longer recorded
+for the memory-allocation functions.
+If no hook functions were successfully installed by
+.BR mtrace (),
+.BR muntrace ()
+does nothing.
+.P
+When
+.BR mtrace ()
+is called, it checks the value of the environment variable
+.BR MALLOC_TRACE ,
+which should contain the pathname of a file in which
+the tracing information is to be recorded.
+If the pathname is successfully opened, it is truncated to zero length.
+.P
+If
+.B MALLOC_TRACE
+is not set,
+or the pathname it specifies is invalid or not writable,
+then no hook functions are installed, and
+.BR mtrace ()
+has no effect.
+In set-user-ID and set-group-ID programs,
+.B MALLOC_TRACE
+is ignored, and
+.BR mtrace ()
+has no effect.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR mtrace (),
+.BR muntrace ()
+T}	Thread safety	MT-Unsafe
+.TE
+.\" FIXME: The marking is different from that in the glibc manual,
+.\" markings in glibc manual are more detailed:
+.\"
+.\"      mtrace: MT-Unsafe env race:mtrace const:malloc_hooks init
+.\"      muntrace: MT-Unsafe race:mtrace const:malloc_hooks locale
+.\"
+.\" But there is something wrong in glibc manual, for example:
+.\" glibc manual says muntrace should have marking locale because it calls
+.\" fprintf(), but muntrace does not execute area which cause locale problem.
+.SH STANDARDS
+GNU.
+.SH NOTES
+In normal usage,
+.BR mtrace ()
+is called once at the start of execution of a program, and
+.BR muntrace ()
+is never called.
+.P
+The tracing output produced after a call to
+.BR mtrace ()
+is textual, but not designed to be human readable.
+The GNU C library provides a Perl script,
+.BR mtrace (1),
+that interprets the trace log and produces human-readable output.
+For best results,
+the traced program should be compiled with debugging enabled,
+so that line-number information is recorded in the executable.
+.P
+The tracing performed by
+.BR mtrace ()
+incurs a performance penalty (if
+.B MALLOC_TRACE
+points to a valid, writable pathname).
+.SH BUGS
+The line-number information produced by
+.BR mtrace (1)
+is not always precise:
+the line number references may refer to the previous or following (nonblank)
+line of the source code.
+.SH EXAMPLES
+The shell session below demonstrates the use of the
+.BR mtrace ()
+function and the
+.BR mtrace (1)
+command in a program that has memory leaks at two different locations.
+The demonstration uses the following program:
+.P
+.in +4n
+.RB "$ " "cat t_mtrace.c"
+.\" SRC BEGIN (t_mtrace.c)
+.EX
+#include <mcheck.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    mtrace();
+\&
+    for (unsigned int j = 0; j < 2; j++)
+        malloc(100);            /* Never freed\-\-a memory leak */
+\&
+    calloc(16, 16);             /* Never freed\-\-a memory leak */
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.P
+When we run the program as follows, we see that
+.BR mtrace ()
+diagnosed memory leaks at two different locations in the program:
+.P
+.in +4n
+.EX
+.RB "$ " "cc \-g t_mtrace.c \-o t_mtrace"
+.RB "$ " "export MALLOC_TRACE=/tmp/t"
+.RB "$ " "./t_mtrace"
+.RB "$ " "mtrace ./t_mtrace $MALLOC_TRACE"
+Memory not freed:
+-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
+   Address     Size     Caller
+0x084c9378     0x64  at /home/cecilia/t_mtrace.c:12
+0x084c93e0     0x64  at /home/cecilia/t_mtrace.c:12
+0x084c9448    0x100  at /home/cecilia/t_mtrace.c:16
+.EE
+.in
+.P
+The first two messages about unfreed memory correspond to the two
+.BR malloc (3)
+calls inside the
+.I for
+loop.
+The final message corresponds to the call to
+.BR calloc (3)
+(which in turn calls
+.BR malloc (3)).
+.SH SEE ALSO
+.BR mtrace (1),
+.BR malloc (3),
+.BR malloc_hook (3),
+.BR mcheck (3)
diff --git a/man/man3/muntrace.3 b/man/man3/muntrace.3
new file mode 100644
index 000000000..2b03d1071
--- /dev/null
+++ b/man/man3/muntrace.3
@@ -0,0 +1 @@
+.so man3/mtrace.3
diff --git a/man/man3/nan.3 b/man/man3/nan.3
new file mode 100644
index 000000000..f0e79b63d
--- /dev/null
+++ b/man/man3/nan.3
@@ -0,0 +1,96 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Based on glibc infopages
+.\"
+.\" Corrections by aeb
+.\"
+.TH nan 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nan, nanf, nanl \- return 'Not a Number'
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double nan(const char *" tagp );
+.BI "float nanf(const char *" tagp );
+.BI "long double nanl(const char *" tagp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR nan (),
+.BR nanf (),
+.BR nanl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions return a representation (determined by
+.IR tagp )
+of a quiet NaN.
+If the implementation does not support
+quiet NaNs, these functions return zero.
+.P
+The call
+.I nan("char\-sequence")
+is equivalent to:
+.P
+.in +4n
+.EX
+strtod("NAN(char\-sequence)", NULL);
+.EE
+.in
+.P
+Similarly, calls to
+.BR nanf ()
+and
+.BR nanl ()
+are equivalent to analogous calls to
+.BR strtof (3)
+and
+.BR strtold (3).
+.P
+The argument
+.I tagp
+is used in an unspecified manner.
+On IEEE 754 systems, there are many representations of NaN, and
+.I tagp
+selects one.
+On other systems it may do nothing.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR nan (),
+.BR nanf (),
+.BR nanl ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.P
+See also IEC 559 and the appendix with
+recommended functions in IEEE 754/IEEE 854.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR isnan (3),
+.BR strtod (3),
+.BR math_error (7)
diff --git a/man/man3/nanf.3 b/man/man3/nanf.3
new file mode 100644
index 000000000..08e9aa7c6
--- /dev/null
+++ b/man/man3/nanf.3
@@ -0,0 +1 @@
+.so man3/nan.3
diff --git a/man/man3/nanl.3 b/man/man3/nanl.3
new file mode 100644
index 000000000..08e9aa7c6
--- /dev/null
+++ b/man/man3/nanl.3
@@ -0,0 +1 @@
+.so man3/nan.3
diff --git a/man/man3/nearbyint.3 b/man/man3/nearbyint.3
new file mode 100644
index 000000000..3300c2c40
--- /dev/null
+++ b/man/man3/nearbyint.3
@@ -0,0 +1 @@
+.so man3/rint.3
diff --git a/man/man3/nearbyintf.3 b/man/man3/nearbyintf.3
new file mode 100644
index 000000000..3300c2c40
--- /dev/null
+++ b/man/man3/nearbyintf.3
@@ -0,0 +1 @@
+.so man3/rint.3
diff --git a/man/man3/nearbyintl.3 b/man/man3/nearbyintl.3
new file mode 100644
index 000000000..3300c2c40
--- /dev/null
+++ b/man/man3/nearbyintl.3
@@ -0,0 +1 @@
+.so man3/rint.3
diff --git a/man/man3/netlink.3 b/man/man3/netlink.3
new file mode 100644
index 000000000..b8f3e1bdc
--- /dev/null
+++ b/man/man3/netlink.3
@@ -0,0 +1,87 @@
+.\" This manpage copyright 1998 by Andi Kleen.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Based on the original comments from Alexey Kuznetsov
+.\" $Id: netlink.3,v 1.1 1999/05/14 17:17:24 freitag Exp $
+.\"
+.TH netlink 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+netlink \- Netlink macros
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <asm/types.h>
+.B #include <linux/netlink.h>
+.P
+.BI "int NLMSG_ALIGN(size_t " len );
+.BI "int NLMSG_LENGTH(size_t " len );
+.BI "int NLMSG_SPACE(size_t " len );
+.BI "void *NLMSG_DATA(struct nlmsghdr *" nlh );
+.BI "struct nlmsghdr *NLMSG_NEXT(struct nlmsghdr *" nlh ", int " len );
+.BI "int NLMSG_OK(struct nlmsghdr *" nlh ", int " len );
+.BI "int NLMSG_PAYLOAD(struct nlmsghdr *" nlh ", int " len );
+.fi
+.SH DESCRIPTION
+.I <linux/netlink.h>
+defines several standard macros to access or create a netlink datagram.
+They are similar in spirit to the macros defined in
+.BR cmsg (3)
+for auxiliary data.
+The buffer passed to and from a netlink socket should
+be accessed using only these macros.
+.TP
+.BR NLMSG_ALIGN ()
+Round the length of a netlink message up to align it properly.
+.TP
+.BR NLMSG_LENGTH ()
+Given the payload length,
+.IR len ,
+this macro returns the aligned length to store in the
+.I nlmsg_len
+field of the
+.IR nlmsghdr .
+.TP
+.BR NLMSG_SPACE ()
+Return the number of bytes that a netlink message with payload of
+.I len
+would occupy.
+.TP
+.BR NLMSG_DATA ()
+Return a pointer to the payload associated with the passed
+.IR nlmsghdr .
+.TP
+.\" this is bizarre, maybe the interface should be fixed.
+.BR NLMSG_NEXT ()
+Get the next
+.I nlmsghdr
+in a multipart message.
+The caller must check if the current
+.I nlmsghdr
+didn't have the
+.B NLMSG_DONE
+set\[em]this function doesn't return NULL on end.
+The
+.I len
+argument is an lvalue containing the remaining length
+of the message buffer.
+This macro decrements it by the length of the message header.
+.TP
+.BR NLMSG_OK ()
+Return true if the netlink message is not truncated and
+is in a form suitable for parsing.
+.TP
+.BR NLMSG_PAYLOAD ()
+Return the length of the payload associated with the
+.IR nlmsghdr .
+.SH VERSIONS
+It is often better to use netlink via
+.I libnetlink
+than via the low-level kernel interface.
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR libnetlink (3),
+.BR netlink (7)
diff --git a/man/man3/newlocale.3 b/man/man3/newlocale.3
new file mode 100644
index 000000000..e6b29f875
--- /dev/null
+++ b/man/man3/newlocale.3
@@ -0,0 +1,356 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH newlocale 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+newlocale, freelocale \- create, modify, and free a locale object
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <locale.h>
+.P
+.BI "locale_t newlocale(int " category_mask ", const char *" locale ,
+.BI "                   locale_t " base );
+.BI "void freelocale(locale_t " locobj );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR newlocale (),
+.BR freelocale ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR newlocale ()
+function creates a new locale object, or modifies an existing object,
+returning a reference to the new or modified object as the function result.
+Whether the call creates a new object or modifies an existing object
+is determined by the value of
+.IR base :
+.IP \[bu] 3
+If
+.I base
+is
+.IR "(locale_t)\ 0" ,
+a new object is created.
+.IP \[bu]
+If
+.I base
+refers to valid existing locale object
+(i.e., an object returned by a previous call to
+.BR newlocale ()
+or
+.BR duplocale (3)),
+then that object is modified by the call.
+If the call is successful, the contents of
+.I base
+are unspecified (in particular, the object referred to by
+.I base
+may be freed, and a new object created).
+Therefore, the caller should ensure that it stops using
+.I base
+before the call to
+.BR newlocale (),
+and should subsequently refer to the modified object via the
+reference returned as the function result.
+If the call fails, the contents of
+.I base
+remain valid and unchanged.
+.P
+If
+.I base
+is the special locale object
+.B LC_GLOBAL_LOCALE
+(see
+.BR duplocale (3)),
+or is not
+.I (locale_t)\ 0
+and is not a valid locale object handle,
+the behavior is undefined.
+.P
+The
+.I category_mask
+argument is a bit mask that specifies the locale categories
+that are to be set in a newly created locale object
+or modified in an existing object.
+The mask is constructed by a bitwise OR of the constants
+.BR LC_ADDRESS_MASK ,
+.BR LC_CTYPE_MASK ,
+.BR LC_COLLATE_MASK ,
+.BR LC_IDENTIFICATION_MASK ,
+.BR LC_MEASUREMENT_MASK ,
+.BR LC_MESSAGES_MASK ,
+.BR LC_MONETARY_MASK ,
+.BR LC_NUMERIC_MASK ,
+.BR LC_NAME_MASK ,
+.BR LC_PAPER_MASK ,
+.BR LC_TELEPHONE_MASK ,
+and
+.BR LC_TIME_MASK .
+Alternatively, the mask can be specified as
+.BR LC_ALL_MASK ,
+which is equivalent to ORing all of the preceding constants.
+.P
+For each category specified in
+.IR category_mask ,
+the locale data from
+.I locale
+will be used in the object returned by
+.BR newlocale ().
+If a new locale object is being created,
+data for all categories not specified in
+.I category_mask
+is taken from the default ("POSIX") locale.
+.P
+The following preset values of
+.I locale
+are defined for all categories that can be specified in
+.IR category_mask :
+.TP
+"POSIX"
+A minimal locale environment for C language programs.
+.TP
+"C"
+Equivalent to "POSIX".
+.TP
+""
+An implementation-defined native environment
+corresponding to the values of the
+.B LC_*
+and
+.B LANG
+environment variables (see
+.BR locale (7)).
+.SS freelocale()
+The
+.BR freelocale ()
+function deallocates the resources associated with
+.IR locobj ,
+a locale object previously returned by a call to
+.BR newlocale ()
+or
+.BR duplocale (3).
+If
+.I locobj
+is
+.B LC_GLOBAL_LOCALE
+or is not valid locale object handle, the results are undefined.
+.P
+Once a locale object has been freed,
+the program should make no further use of it.
+.SH RETURN VALUE
+On success,
+.BR newlocale ()
+returns a handle that can be used in calls to
+.BR duplocale (3),
+.BR freelocale (),
+and other functions that take a
+.I locale_t
+argument.
+On error,
+.BR newlocale ()
+returns
+.IR "(locale_t)\ 0",
+and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+One or more bits in
+.I category_mask
+do not correspond to a valid locale category.
+.TP
+.B EINVAL
+.I locale
+is NULL.
+.TP
+.B ENOENT
+.I locale
+is not a string pointer referring to a valid locale.
+.TP
+.B ENOMEM
+Insufficient memory to create a locale object.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.3.
+.SH NOTES
+Each locale object created by
+.BR newlocale ()
+should be deallocated using
+.BR freelocale ().
+.SH EXAMPLES
+The program below takes up to two command-line arguments,
+which each identify locales.
+The first argument is required, and is used to set the
+.B LC_NUMERIC
+category in a locale object created using
+.BR newlocale ().
+The second command-line argument is optional;
+if it is present, it is used to set the
+.B LC_TIME
+category of the locale object.
+.P
+Having created and initialized the locale object,
+the program then applies it using
+.BR uselocale (3),
+and then tests the effect of the locale changes by:
+.IP (1) 5
+Displaying a floating-point number with a fractional part.
+This output will be affected by the
+.B LC_NUMERIC
+setting.
+In many European-language locales,
+the fractional part of the number is separated from the integer part
+using a comma, rather than a period.
+.IP (2)
+Displaying the date.
+The format and language of the output will be affected by the
+.B LC_TIME
+setting.
+.P
+The following shell sessions show some example runs of this program.
+.P
+Set the
+.B LC_NUMERIC
+category to
+.I fr_FR
+(French):
+.P
+.in +4n
+.EX
+$ \fB./a.out fr_FR\fP
+123456,789
+Fri Mar  7 00:25:08 2014
+.EE
+.in
+.P
+Set the
+.B LC_NUMERIC
+category to
+.I fr_FR
+(French),
+and the
+.B LC_TIME
+category to
+.I it_IT
+(Italian):
+.P
+.in +4n
+.EX
+$ \fB./a.out fr_FR it_IT\fP
+123456,789
+ven 07 mar 2014 00:26:01 CET
+.EE
+.in
+.P
+Specify the
+.B LC_TIME
+setting as an empty string,
+which causes the value to be taken from environment variable settings
+(which, here, specify
+.IR mi_NZ ,
+New Zealand Māori):
+.P
+.in +4n
+.EX
+$ LC_ALL=mi_NZ ./a.out fr_FR ""
+123456,789
+Te Paraire, te 07 o Poutū\-te\-rangi, 2014 00:38:44 CET
+.EE
+.in
+.SS Program source
+.\" SRC BEGIN (newlocale.c)
+.EX
+#define _XOPEN_SOURCE 700
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+int
+main(int argc, char *argv[])
+{
+    char buf[100];
+    time_t t;
+    size_t s;
+    struct tm *tm;
+    locale_t loc, nloc;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s locale1 [locale2]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Create a new locale object, taking the LC_NUMERIC settings
+       from the locale specified in argv[1]. */
+\&
+    loc = newlocale(LC_NUMERIC_MASK, argv[1], (locale_t) 0);
+    if (loc == (locale_t) 0)
+        errExit("newlocale");
+\&
+    /* If a second command\-line argument was specified, modify the
+       locale object to take the LC_TIME settings from the locale
+       specified in argv[2]. We assign the result of this newlocale()
+       call to \[aq]nloc\[aq] rather than \[aq]loc\[aq], since in some cases, we might
+       want to preserve \[aq]loc\[aq] if this call fails. */
+\&
+    if (argc > 2) {
+        nloc = newlocale(LC_TIME_MASK, argv[2], loc);
+        if (nloc == (locale_t) 0)
+            errExit("newlocale");
+        loc = nloc;
+    }
+\&
+    /* Apply the newly created locale to this thread. */
+\&
+    uselocale(loc);
+\&
+    /* Test effect of LC_NUMERIC. */
+\&
+    printf("%8.3f\en", 123456.789);
+\&
+    /* Test effect of LC_TIME. */
+\&
+    t = time(NULL);
+    tm = localtime(&t);
+    if (tm == NULL)
+        errExit("time");
+\&
+    s = strftime(buf, sizeof(buf), "%c", tm);
+    if (s == 0)
+        errExit("strftime");
+\&
+    printf("%s\en", buf);
+\&
+    /* Free the locale object. */
+\&
+    uselocale(LC_GLOBAL_LOCALE);    /* So \[aq]loc\[aq] is no longer in use */
+    freelocale(loc);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR locale (1),
+.BR duplocale (3),
+.BR setlocale (3),
+.BR uselocale (3),
+.BR locale (5),
+.BR locale (7)
diff --git a/man/man3/nextafter.3 b/man/man3/nextafter.3
new file mode 100644
index 000000000..a33c1c4f6
--- /dev/null
+++ b/man/man3/nextafter.3
@@ -0,0 +1,200 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Based on glibc infopages
+.\"
+.TH nextafter 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl \-
+floating-point number manipulation
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double nextafter(double " x ", double " y );
+.BI "float nextafterf(float " x ", float " y );
+.BI "long double nextafterl(long double " x ", long double " y );
+.P
+.BI "double nexttoward(double " x ", long double " y );
+.BI "float nexttowardf(float " x ", long double " y );
+.BI "long double nexttowardl(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR nextafter ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR nextafterf (),
+.BR nextafterl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR nexttoward (),
+.BR nexttowardf (),
+.BR nexttowardl ():
+.nf
+    _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE
+        || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR nextafter (),
+.BR nextafterf (),
+and
+.BR nextafterl ()
+functions return the next representable floating-point value following
+.I x
+in the direction of
+.IR y .
+If
+.I y
+is less than
+.IR x ,
+these functions will return the largest representable number less than
+.IR x .
+.P
+If
+.I x
+equals
+.IR y ,
+the functions return
+.IR y .
+.P
+The
+.BR nexttoward (),
+.BR nexttowardf (),
+and
+.BR nexttowardl ()
+functions do the same as the corresponding
+.BR nextafter ()
+functions, except that they have a
+.I "long double"
+second argument.
+.SH RETURN VALUE
+On success,
+these functions return the next representable floating-point value after
+.I x
+in the direction of
+.IR y .
+.P
+If
+.I x
+equals
+.IR y ,
+then
+.I y
+(cast to the same type as
+.IR x )
+is returned.
+.P
+If
+.I x
+or
+.I y
+is a NaN,
+a NaN is returned.
+.P
+If
+.I x
+is finite,
+.\" e.g., DBL_MAX
+and the result would overflow,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the correct mathematical sign.
+.P
+If
+.I x
+is not equal to
+.IR y ,
+and the correct function result would be subnormal, zero, or underflow,
+a range error occurs,
+and either the correct value (if it can be represented),
+or 0.0, is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result overflow
+.\" e.g., nextafter(DBL_MAX, HUGE_VAL);
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error: result is subnormal or underflows
+.\" e.g., nextafter(DBL_MIN, 0.0);
+.I errno
+is set to
+.BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR nextafter (),
+.BR nextafterf (),
+.BR nextafterl (),
+.BR nexttoward (),
+.BR nexttowardf (),
+.BR nexttowardl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.P
+This function is defined in IEC 559 (and the appendix with
+recommended functions in IEEE 754/IEEE 854).
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH BUGS
+In glibc 2.5 and earlier, these functions do not raise an underflow
+floating-point
+.RB ( FE_UNDERFLOW )
+exception when an underflow occurs.
+.P
+Before glibc 2.23
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6799
+these functions did not set
+.IR errno .
+.SH SEE ALSO
+.BR nearbyint (3)
diff --git a/man/man3/nextafterf.3 b/man/man3/nextafterf.3
new file mode 100644
index 000000000..531e48f47
--- /dev/null
+++ b/man/man3/nextafterf.3
@@ -0,0 +1 @@
+.so man3/nextafter.3
diff --git a/man/man3/nextafterl.3 b/man/man3/nextafterl.3
new file mode 100644
index 000000000..531e48f47
--- /dev/null
+++ b/man/man3/nextafterl.3
@@ -0,0 +1 @@
+.so man3/nextafter.3
diff --git a/man/man3/nextdown.3 b/man/man3/nextdown.3
new file mode 100644
index 000000000..853b38897
--- /dev/null
+++ b/man/man3/nextdown.3
@@ -0,0 +1 @@
+.so man3/nextup.3
diff --git a/man/man3/nextdownf.3 b/man/man3/nextdownf.3
new file mode 100644
index 000000000..853b38897
--- /dev/null
+++ b/man/man3/nextdownf.3
@@ -0,0 +1 @@
+.so man3/nextup.3
diff --git a/man/man3/nextdownl.3 b/man/man3/nextdownl.3
new file mode 100644
index 000000000..853b38897
--- /dev/null
+++ b/man/man3/nextdownl.3
@@ -0,0 +1 @@
+.so man3/nextup.3
diff --git a/man/man3/nexttoward.3 b/man/man3/nexttoward.3
new file mode 100644
index 000000000..531e48f47
--- /dev/null
+++ b/man/man3/nexttoward.3
@@ -0,0 +1 @@
+.so man3/nextafter.3
diff --git a/man/man3/nexttowardf.3 b/man/man3/nexttowardf.3
new file mode 100644
index 000000000..531e48f47
--- /dev/null
+++ b/man/man3/nexttowardf.3
@@ -0,0 +1 @@
+.so man3/nextafter.3
diff --git a/man/man3/nexttowardl.3 b/man/man3/nexttowardl.3
new file mode 100644
index 000000000..531e48f47
--- /dev/null
+++ b/man/man3/nexttowardl.3
@@ -0,0 +1 @@
+.so man3/nextafter.3
diff --git a/man/man3/nextup.3 b/man/man3/nextup.3
new file mode 100644
index 000000000..618c6b2de
--- /dev/null
+++ b/man/man3/nextup.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH nextup 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nextup, nextupf, nextupl, nextdown, nextdownf, nextdownl \-
+return next floating-point number toward positive/negative infinity
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "     /* See feature_test_macros(7) */"
+.B #include <math.h>
+.P
+.BI "double nextup(double " x );
+.BI "float nextupf(float " x );
+.BI "long double nextupl(long double " x );
+.P
+.BI "double nextdown(double " x );
+.BI "float nextdownf(float " x );
+.BI "long double nextdownl(long double " x );
+.fi
+.SH DESCRIPTION
+The
+.BR nextup (),
+.BR nextupf (),
+and
+.BR nextupl ()
+functions return the next representable floating-point number greater than
+.IR x .
+.P
+If
+.I x
+is the smallest representable negative number in the corresponding type,
+these functions return \-0.
+If
+.I x
+is 0, the returned value is the smallest representable positive number
+of the corresponding type.
+.P
+If
+.I x
+is positive infinity, the returned value is positive infinity.
+If
+.I x
+is negative infinity,
+the returned value is the largest representable finite negative number
+of the corresponding type.
+.P
+If
+.I x
+is Nan,
+the returned value is NaN.
+.P
+The value returned by
+.I nextdown(x)
+is
+.IR \-nextup(\-x) ,
+and similarly for the other types.
+.SH RETURN VALUE
+See DESCRIPTION.
+.\" .SH ERRORS
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR nextup (),
+.BR nextupf (),
+.BR nextupl (),
+.BR nextdown (),
+.BR nextdownf (),
+.BR nextdownl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+These functions are described in
+.I IEEE Std 754-2008 - Standard for Floating-Point Arithmetic
+and
+.IR "ISO/IEC TS 18661".
+.SH HISTORY
+glibc 2.24.
+.SH SEE ALSO
+.BR nearbyint (3),
+.BR nextafter (3)
diff --git a/man/man3/nextupf.3 b/man/man3/nextupf.3
new file mode 100644
index 000000000..853b38897
--- /dev/null
+++ b/man/man3/nextupf.3
@@ -0,0 +1 @@
+.so man3/nextup.3
diff --git a/man/man3/nextupl.3 b/man/man3/nextupl.3
new file mode 100644
index 000000000..853b38897
--- /dev/null
+++ b/man/man3/nextupl.3
@@ -0,0 +1 @@
+.so man3/nextup.3
diff --git a/man/man3/nftw.3 b/man/man3/nftw.3
new file mode 100644
index 000000000..1a5c9c928
--- /dev/null
+++ b/man/man3/nftw.3
@@ -0,0 +1 @@
+.so man3/ftw.3
diff --git a/man/man3/nl_langinfo.3 b/man/man3/nl_langinfo.3
new file mode 100644
index 000000000..24cdfe88e
--- /dev/null
+++ b/man/man3/nl_langinfo.3
@@ -0,0 +1,353 @@
+'\" t
+.\" Copyright (c) 2001 Markus Kuhn <mkuhn@acm.org>
+.\" and Copyright (c) 2015 Sam Varshavchik <mrsam@courier-mta.com>
+.\" and Copyright (c) 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 manual
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.\" Corrected prototype, 2002-10-18, aeb
+.\"
+.TH nl_langinfo 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nl_langinfo, nl_langinfo_l \- query language and locale information
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <langinfo.h>
+.P
+.BI "char *nl_langinfo(nl_item " item );
+.BI "char *nl_langinfo_l(nl_item " item ", locale_t " locale );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR nl_langinfo_l ():
+.nf
+    Since glibc 2.24:
+        _POSIX_C_SOURCE >= 200809L
+    glibc 2.23 and earlier:
+        _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR nl_langinfo ()
+and
+.BR nl_langinfo_l ()
+functions provide access to locale information
+in a more flexible way than
+.BR localeconv (3).
+.BR nl_langinfo ()
+returns a string which is the value corresponding to
+\fIitem\fP in the program's current global
+locale.
+.BR nl_langinfo_l ()
+returns a string which is the value corresponding to \fIitem\fP
+for the locale identified by the locale object \fIlocale\fP,
+which was previously created by
+.BR newlocale (3).
+Individual and additional elements of the locale categories can
+be queried.
+.P
+Examples for the locale elements that can be specified in \fIitem\fP
+using the constants defined in \fI<langinfo.h>\fP are:
+.TP
+.BR CODESET \ (LC_CTYPE)
+Return a string with the name of the character encoding used in the
+selected locale, such as "UTF\-8", "ISO\-8859\-1", or "ANSI_X3.4\-1968"
+(better known as US-ASCII).
+This is the same string that you get with
+"locale charmap".
+For a list of character encoding names,
+try "locale \-m" (see
+.BR locale (1)).
+.TP
+.BR D_T_FMT \ (LC_TIME)
+Return a string that can be used as a format string for
+.BR strftime (3)
+to represent time and date in a locale-specific way
+.RB ( %c
+conversion specification).
+.TP
+.BR D_FMT \ (LC_TIME)
+Return a string that can be used as a format string for
+.BR strftime (3)
+to represent a date in a locale-specific way
+.RB ( %x
+conversion specification).
+.TP
+.BR T_FMT \ (LC_TIME)
+Return a string that can be used as a format string for
+.BR strftime (3)
+to represent a time in a locale-specific way
+.RB ( %X
+conversion specification).
+.TP
+.BR AM_STR \ (LC_TIME)
+Return a string that represents affix for ante meridiem (before noon, "AM")
+time.
+(Used in
+.B %p
+.BR strftime (3)
+conversion specification.)
+.TP
+.BR PM_STR \ (LC_TIME)
+Return a string that represents affix for post meridiem (before midnight, "PM")
+time.
+(Used in
+.B %p
+.BR strftime (3)
+conversion specification.)
+.TP
+.BR T_FMT_AMPM \ (LC_TIME)
+Return a string that can be used as a format string for
+.BR strftime (3)
+to represent a time in a.m. or p.m. notation in a locale-specific way
+.RB ( %r
+conversion specification).
+.TP
+.BR ERA \ (LC_TIME)
+Return era description, which contains information about how years are counted
+and displayed for each era in a locale.
+Each era description segment shall have the format:
+.RS
+.IP
+.IR direction : offset : start_date : end_date : era_name : era_format
+.RE
+.IP
+according to the definitions below:
+.RS
+.TP 12
+.I direction
+Either a
+.RB \[dq] + "\[dq] or a \[dq]" - \[dq]
+character.
+The
+.RB \[dq] + \[dq]
+means that years increase from the
+.I start_date
+towards the
+.IR end_date ,
+.RB \[dq] - \[dq]
+means the opposite.
+.TP
+.I offset
+The epoch year of the
+.IR start_date .
+.TP
+.I start_date
+A date in the form
+.IR yyyy / mm / dd ,
+where
+.IR yyyy ", " mm ", and " dd
+are the year, month, and day numbers respectively of the start of the era.
+.TP
+.I end_date
+The ending date of the era, in the same format as the
+.IR start_date ,
+or one of the two special values
+.RB \[dq] -* \[dq]
+(minus infinity) or
+.RB \[dq] +* \[dq]
+(plus infinity).
+.TP
+.I era_name
+The name of the era, corresponding to the
+.B %EC
+.BR strftime (3)
+conversion specification.
+.TP
+.I era_format
+The format of the year in the era, corresponding to the
+.B %EY
+.BR strftime (3)
+conversion specification.
+.RE
+.IP
+Era description segments are separated by semicolons.
+Most locales do not define this value.
+Examples of locales that do define this value are the Japanese and Thai
+locales.
+.TP
+.BR ERA_D_T_FMT \ (LC_TIME)
+Return a string that can be used as a format string for
+.BR strftime (3)
+for alternative representation of time and date in a locale-specific way
+.RB ( %Ec
+conversion specification).
+.TP
+.BR ERA_D_FMT \ (LC_TIME)
+Return a string that can be used as a format string for
+.BR strftime (3)
+for alternative representation of a date in a locale-specific way
+.RB ( %Ex
+conversion specification).
+.TP
+.BR ERA_T_FMT \ (LC_TIME)
+Return a string that can be used as a format string for
+.BR strftime (3)
+for alternative representation of a time in a locale-specific way
+.RB ( %EX
+conversion specification).
+.TP
+.BR DAY_ "{1\[en]7} (LC_TIME)"
+Return name of the \fIn\fP-th day of the week.
+[Warning: this follows
+the US convention DAY_1 = Sunday, not the international convention
+(ISO\~8601) that Monday is the first day of the week.]
+(Used in
+.B %A
+.BR strftime (3)
+conversion specification.)
+.TP
+.BR ABDAY_ "{1\[en]7} (LC_TIME)"
+Return abbreviated name of the \fIn\fP-th day of the week.
+(Used in
+.B %a
+.BR strftime (3)
+conversion specification.)
+.TP
+.BR MON_ "{1\[en]12} (LC_TIME)"
+Return name of the \fIn\fP-th month.
+(Used in
+.B %B
+.BR strftime (3)
+conversion specification.)
+.TP
+.BR ABMON_ "{1\[en]12} (LC_TIME)"
+Return abbreviated name of the \fIn\fP-th month.
+(Used in
+.B %b
+.BR strftime (3)
+conversion specification.)
+.TP
+.BR RADIXCHAR \ (LC_NUMERIC)
+Return radix character (decimal dot, decimal comma, etc.).
+.TP
+.BR THOUSEP \ (LC_NUMERIC)
+Return separator character for thousands (groups of three digits).
+.TP
+.BR YESEXPR \ (LC_MESSAGES)
+Return a regular expression that can be used with the
+.BR regex (3)
+function to recognize a positive response to a yes/no question.
+.TP
+.BR NOEXPR \ (LC_MESSAGES)
+Return a regular expression that can be used with the
+.BR regex (3)
+function to recognize a negative response to a yes/no question.
+.TP
+.BR CRNCYSTR \ (LC_MONETARY)
+Return the currency symbol, preceded by "\-" if the symbol should
+appear before the value, "+" if the symbol should appear after the
+value, or "." if the symbol should replace the radix character.
+.P
+The above list covers just some examples of items that can be requested.
+For a more detailed list, consult
+.IR "The GNU C Library Reference Manual" .
+.SH RETURN VALUE
+On success, these functions return a pointer to a string which
+is the value corresponding to
+.I item
+in the specified locale.
+.P
+If no locale has been selected by
+.BR setlocale (3)
+for the appropriate category,
+.BR nl_langinfo ()
+return a pointer to the corresponding string in the "C" locale.
+The same is true of
+.BR nl_langinfo_l ()
+if
+.I locale
+specifies a locale where
+.I langinfo
+data is not defined.
+.P
+If \fIitem\fP is not valid, a pointer to an empty string is returned.
+.P
+The pointer returned by these functions may point to static data that
+may be overwritten, or the pointer itself may be invalidated,
+by a subsequent call to
+.BR nl_langinfo (),
+.BR nl_langinfo_l (),
+or
+.BR setlocale (3).
+The same statements apply to
+.BR nl_langinfo_l ()
+if the locale object referred to by
+.I locale
+is freed or modified by
+.BR freelocale (3)
+or
+.BR newlocale (3).
+.P
+POSIX specifies that the application may not modify
+the string returned by these functions.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR nl_langinfo ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SUSv2.
+.SH NOTES
+The behavior of
+.BR nl_langinfo_l ()
+is undefined if
+.I locale
+is the special locale object
+.B LC_GLOBAL_LOCALE
+or is not a valid locale object handle.
+.SH EXAMPLES
+The following program sets the character type and the numeric locale
+according to the environment and queries the terminal character set and
+the radix character.
+.P
+.\" SRC BEGIN (nl_langinfo.c)
+.EX
+#include <langinfo.h>
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    setlocale(LC_CTYPE, "");
+    setlocale(LC_NUMERIC, "");
+\&
+    printf("%s\en", nl_langinfo(CODESET));
+    printf("%s\en", nl_langinfo(RADIXCHAR));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR locale (1),
+.BR localeconv (3),
+.BR setlocale (3),
+.BR charsets (7),
+.BR locale (7)
+.P
+The GNU C Library Reference Manual
diff --git a/man/man3/nl_langinfo_l.3 b/man/man3/nl_langinfo_l.3
new file mode 100644
index 000000000..36c3e35c0
--- /dev/null
+++ b/man/man3/nl_langinfo_l.3
@@ -0,0 +1 @@
+.so man3/nl_langinfo.3
diff --git a/man/man3/nrand48.3 b/man/man3/nrand48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/nrand48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/nrand48_r.3 b/man/man3/nrand48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/nrand48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/ntohl.3 b/man/man3/ntohl.3
new file mode 100644
index 000000000..ba374e841
--- /dev/null
+++ b/man/man3/ntohl.3
@@ -0,0 +1 @@
+.so man3/byteorder.3
diff --git a/man/man3/ntohs.3 b/man/man3/ntohs.3
new file mode 100644
index 000000000..ba374e841
--- /dev/null
+++ b/man/man3/ntohs.3
@@ -0,0 +1 @@
+.so man3/byteorder.3
diff --git a/man/man3/ntp_adjtime.3 b/man/man3/ntp_adjtime.3
new file mode 100644
index 000000000..b08b9c801
--- /dev/null
+++ b/man/man3/ntp_adjtime.3
@@ -0,0 +1 @@
+.so man2/adjtimex.2
diff --git a/man/man3/ntp_gettime.3 b/man/man3/ntp_gettime.3
new file mode 100644
index 000000000..62283a4f9
--- /dev/null
+++ b/man/man3/ntp_gettime.3
@@ -0,0 +1,135 @@
+'\" t
+.\" Copyright (c) 2016 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH ntp_gettime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ntp_gettime, ntp_gettimex  \- get time parameters (NTP daemon interface)
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/timex.h>
+.P
+.BI "int ntp_gettime(struct ntptimeval *" ntv );
+.BI "int ntp_gettimex(struct ntptimeval *" ntv );
+.fi
+.SH DESCRIPTION
+Both of these APIs return information to the caller via the
+.I ntv
+argument, a structure of the following type:
+.P
+.in +4n
+.EX
+struct ntptimeval {
+    struct timeval time;    /* Current time */
+    long maxerror;          /* Maximum error */
+    long esterror;          /* Estimated error */
+    long tai;               /* TAI offset */
+\&
+    /* Further padding bytes allowing for future expansion */
+};
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I time
+The current time, expressed as a
+.I timeval
+structure:
+.IP
+.in +4n
+.EX
+struct timeval {
+    time_t      tv_sec;   /* Seconds since the Epoch */
+    suseconds_t tv_usec;  /* Microseconds */
+};
+.EE
+.in
+.TP
+.I maxerror
+Maximum error, in microseconds.
+This value can be initialized by
+.BR ntp_adjtime (3),
+and is increased periodically (on Linux: each second),
+but is clamped to an upper limit (the kernel constant
+.BR NTP_PHASE_MAX ,
+with a value of 16,000).
+.TP
+.I esterror
+Estimated error, in microseconds.
+This value can be set via
+.BR ntp_adjtime (3)
+to contain an estimate of the difference between the system clock
+and the true time.
+This value is not used inside the kernel.
+.TP
+.I tai
+TAI (Atomic International Time) offset.
+.P
+.BR ntp_gettime ()
+returns an
+.I ntptimeval
+structure in which the
+.IR time ,
+.IR maxerror ,
+and
+.I esterror
+fields are filled in.
+.P
+.BR ntp_gettimex ()
+performs the same task as
+.BR ntp_gettime (),
+but also returns information in the
+.I tai
+field.
+.SH RETURN VALUE
+The return values for
+.BR ntp_gettime ()
+and
+.BR ntp_gettimex ()
+are as for
+.BR adjtimex (2).
+Given a correct pointer argument, these functions always succeed.
+.\" FIXME . the info page incorrectly describes the return values.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ntp_gettime (),
+.BR ntp_gettimex ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR ntp_gettime ()
+NTP Kernel Application Program Interface.
+.TP
+.BR ntp_gettimex ()
+GNU.
+.SH HISTORY
+.TP
+.BR ntp_gettime ()
+glibc 2.1.
+.TP
+.BR ntp_gettimex ()
+glibc 2.12.
+.SH SEE ALSO
+.BR adjtimex (2),
+.BR ntp_adjtime (3),
+.BR time (7)
+.P
+.ad l
+.UR http://www.slac.stanford.edu/comp/unix/\:package/\:rtems/\:src/\:ssrlApps/\:ntpNanoclock/\:api.htm
+NTP "Kernel Application Program Interface"
+.UE
diff --git a/man/man3/ntp_gettimex.3 b/man/man3/ntp_gettimex.3
new file mode 100644
index 000000000..142d76b59
--- /dev/null
+++ b/man/man3/ntp_gettimex.3
@@ -0,0 +1 @@
+.so man3/ntp_gettime.3
diff --git a/man/man3/offsetof.3 b/man/man3/offsetof.3
new file mode 100644
index 000000000..7eea85c10
--- /dev/null
+++ b/man/man3/offsetof.3
@@ -0,0 +1,110 @@
+.\" Copyright (C) 2006 Justin Pryzby <pryzbyj@justinpryzby.com>
+.\"     and Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Permission is hereby granted, free of charge, to any person obtaining
+.\" a copy of this software and associated documentation files (the
+.\" "Software"), to deal in the Software without restriction, including
+.\" without limitation the rights to use, copy, modify, merge, publish,
+.\" distribute, sublicense, and/or sell copies of the Software, and to
+.\" permit persons to whom the Software is furnished to do so, subject to
+.\" the following conditions:
+.\"
+.\" The above copyright notice and this permission notice shall be
+.\" included in all copies or substantial portions of the Software.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+.\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+.\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+.\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+.\" %%%LICENSE_END
+.\"
+.\" References:
+.\"   /usr/lib/gcc/i486-linux-gnu/4.1.1/include/stddef.h
+.\"   glibc-doc
+.TH offsetof 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+offsetof \- offset of a structure member
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stddef.h>
+.P
+.BI "size_t offsetof(" type ", " member );
+.fi
+.SH DESCRIPTION
+The macro
+.BR offsetof ()
+returns the offset of the field
+.I member
+from the start of the structure
+.IR type .
+.P
+This macro is useful because the sizes of the fields that compose
+a structure can vary across implementations,
+and compilers may insert different numbers of padding
+bytes between fields.
+Consequently, an element's offset is not necessarily
+given by the sum of the sizes of the previous elements.
+.P
+A compiler error will result if
+.I member
+is not aligned to a byte boundary
+(i.e., it is a bit field).
+.SH RETURN VALUE
+.BR offsetof ()
+returns the offset of the given
+.I member
+within the given
+.IR type ,
+in units of bytes.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89.
+.SH EXAMPLES
+On a Linux/i386 system, when compiled using the default
+.BR gcc (1)
+options, the program below produces the following output:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+offsets: i=0; c=4; d=8 a=16
+sizeof(struct s)=16
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (offsetof.c)
+.EX
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    struct s {
+        int i;
+        char c;
+        double d;
+        char a[];
+    };
+\&
+    /* Output is compiler dependent */
+\&
+    printf("offsets: i=%zu; c=%zu; d=%zu a=%zu\en",
+           offsetof(struct s, i), offsetof(struct s, c),
+           offsetof(struct s, d), offsetof(struct s, a));
+    printf("sizeof(struct s)=%zu\en", sizeof(struct s));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
diff --git a/man/man3/on_exit.3 b/man/man3/on_exit.3
new file mode 100644
index 000000000..08fceba13
--- /dev/null
+++ b/man/man3/on_exit.3
@@ -0,0 +1,105 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-04-02, David Metcalfe
+.\" Modified 1993-07-25, Rik Faith (faith@cs.unc.edu)
+.TH on_exit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+on_exit \- register a function to be called at normal process termination
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int on_exit(void (*" function ")(int, void *), void *" arg );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR on_exit ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR on_exit ()
+function registers the given
+.I function
+to be
+called at normal process termination, whether via
+.BR exit (3)
+or via return from the program's
+.IR main ().
+The
+.I function
+is passed the status argument given to the last call to
+.BR exit (3)
+and the
+.I arg
+argument from
+.BR on_exit ().
+.P
+The same function may be registered multiple times:
+it is called once for each registration.
+.P
+When a child process is created via
+.BR fork (2),
+it inherits copies of its parent's registrations.
+Upon a successful call to one of the
+.BR exec (3)
+functions, all registrations are removed.
+.SH RETURN VALUE
+The
+.BR on_exit ()
+function returns the value 0 if successful; otherwise
+it returns a nonzero value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR on_exit ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SunOS 4, glibc.
+Removed in Solaris (SunOS 5).
+Use the standard
+.BR atexit (3)
+instead.
+.SH CAVEATS
+By the time
+.I function
+is executed, stack
+.RI ( auto )
+variables may already have gone out of scope.
+Therefore,
+.I arg
+should not be a pointer to a stack variable;
+it may however be a pointer to a heap variable or a global variable.
+.SH SEE ALSO
+.BR _exit (2),
+.BR atexit (3),
+.BR exit (3)
diff --git a/man/man3/open_memstream.3 b/man/man3/open_memstream.3
new file mode 100644
index 000000000..63a1ea9be
--- /dev/null
+++ b/man/man3/open_memstream.3
@@ -0,0 +1,141 @@
+'\" t
+.\" Copyright 2005, 2012, 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" 2008-12-04, Petr Baudis <pasky@suse.cz>: Document open_wmemstream()
+.\"
+.TH open_memstream 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+open_memstream, open_wmemstream \- open a dynamic memory buffer stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "FILE *open_memstream(char **" ptr ", size_t *" sizeloc );
+.P
+.B #include <wchar.h>
+.P
+.BI "FILE *open_wmemstream(wchar_t **" ptr ", size_t *" sizeloc );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR open_memstream (),
+.BR open_wmemstream ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR open_memstream ()
+function opens a stream for writing to a memory buffer.
+The function dynamically allocates the buffer,
+and the buffer automatically grows as needed.
+Initially, the buffer has a size of zero.
+After closing the stream, the caller should
+.BR free (3)
+this buffer.
+.P
+The locations pointed to by
+.I ptr
+and
+.I sizeloc
+are used to report, respectively,
+the current location and the size of the buffer.
+The locations referred to by these pointers are updated
+each time the stream is flushed
+.RB ( fflush (3))
+and when the stream is closed
+.RB ( fclose (3)).
+These values remain valid only as long as the caller
+performs no further output on the stream.
+If further output is performed, then the stream
+must again be flushed before trying to access these values.
+.P
+A null byte is maintained at the end of the buffer.
+This byte is
+.I not
+included in the size value stored at
+.IR sizeloc .
+.P
+The stream maintains the notion of a current position,
+which is initially zero (the start of the buffer).
+Each write operation implicitly adjusts the buffer position.
+The stream's buffer position can be explicitly changed with
+.BR fseek (3)
+or
+.BR fseeko (3).
+Moving the buffer position past the end
+of the data already written fills the intervening space with
+null characters.
+.P
+The
+.BR open_wmemstream ()
+is similar to
+.BR open_memstream (),
+but operates on wide characters instead of bytes.
+.SH RETURN VALUE
+Upon successful completion,
+.BR open_memstream ()
+and
+.BR open_wmemstream ()
+return a
+.I FILE
+pointer.
+Otherwise, NULL is returned and
+.I errno
+is set to indicate the error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR open_memstream (),
+.BR open_wmemstream ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR open_memstream ()
+glibc 1.0.x.
+.TP
+.BR open_wmemstream ()
+glibc 2.4.
+.SH NOTES
+There is no file descriptor associated with the file stream
+returned by these functions
+(i.e.,
+.BR fileno (3)
+will return an error if called on the returned stream).
+.SH BUGS
+Before glibc 2.7, seeking past the end of a stream created by
+.BR open_memstream ()
+does not enlarge the buffer; instead the
+.BR fseek (3)
+call fails, returning \-1.
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=1996
+.SH EXAMPLES
+See
+.BR fmemopen (3).
+.SH SEE ALSO
+.BR fmemopen (3),
+.BR fopen (3),
+.BR setbuf (3)
diff --git a/man/man3/open_wmemstream.3 b/man/man3/open_wmemstream.3
new file mode 100644
index 000000000..a113f1345
--- /dev/null
+++ b/man/man3/open_wmemstream.3
@@ -0,0 +1 @@
+.so man3/open_memstream.3
diff --git a/man/man3/opendir.3 b/man/man3/opendir.3
new file mode 100644
index 000000000..9222310a0
--- /dev/null
+++ b/man/man3/opendir.3
@@ -0,0 +1,145 @@
+'\" t
+.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:46:01 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 11 June 1995 by Andries Brouwer (aeb@cwi.nl)
+.\" 2007-07-30 Ulrich Drepper <drepper@redhat.com>: document fdopendir().
+.TH opendir 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+opendir, fdopendir \- open a directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <dirent.h>
+.P
+.BI "DIR *opendir(const char *" name );
+.BI "DIR *fdopendir(int " fd );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR fdopendir ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR opendir ()
+function opens a directory stream corresponding to the
+directory \fIname\fP, and returns a pointer to the directory stream.
+The stream is positioned at the first entry in the directory.
+.P
+The
+.BR fdopendir ()
+function
+is like
+.BR opendir (),
+but returns a directory stream for the directory referred
+to by the open file descriptor
+.IR fd .
+After a successful call to
+.BR fdopendir (),
+.I fd
+is used internally by the implementation,
+and should not otherwise be used by the application.
+.SH RETURN VALUE
+The
+.BR opendir ()
+and
+.BR fdopendir ()
+functions return a pointer to the directory stream.
+On error, NULL is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Permission denied.
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor opened for reading.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+Directory does not exist, or \fIname\fP is an empty string.
+.TP
+.B ENOMEM
+Insufficient memory to complete the operation.
+.TP
+.B ENOTDIR
+\fIname\fP is not a directory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR opendir (),
+.BR fdopendir ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH STANDARDS
+.TP
+.BR opendir ()
+SVr4, 4.3BSD, POSIX.1-2001.
+.TP
+.BR fdopendir ()
+POSIX.1-2008.
+glibc 2.4.
+.SH NOTES
+Filename entries can be read from a directory stream using
+.BR readdir (3).
+.P
+The underlying file descriptor of the directory stream can be obtained using
+.BR dirfd (3).
+.P
+The
+.BR opendir ()
+function sets the close-on-exec flag for the file descriptor underlying the
+.IR "DIR *" .
+The
+.BR fdopendir ()
+function leaves the setting of the close-on-exec
+flag unchanged for the file descriptor,
+.IR fd .
+POSIX.1-200x leaves it unspecified whether a successful call to
+.BR fdopendir ()
+will set the close-on-exec flag for the file descriptor,
+.IR fd .
+.SH SEE ALSO
+.BR open (2),
+.BR closedir (3),
+.BR dirfd (3),
+.BR readdir (3),
+.BR rewinddir (3),
+.BR scandir (3),
+.BR seekdir (3),
+.BR telldir (3)
diff --git a/man/man3/openlog.3 b/man/man3/openlog.3
new file mode 100644
index 000000000..ec352b291
--- /dev/null
+++ b/man/man3/openlog.3
@@ -0,0 +1 @@
+.so man3/syslog.3
diff --git a/man/man3/openpty.3 b/man/man3/openpty.3
new file mode 100644
index 000000000..35ba068e8
--- /dev/null
+++ b/man/man3/openpty.3
@@ -0,0 +1,179 @@
+'\" t
+.\" Copyright (c) OpenBSD Group
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\" Converted into a manpage again by Martin Schulze <joey@infodrom.org>
+.\"
+.\" Added -lutil remark, 030718
+.\"
+.TH openpty 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+openpty, login_tty, forkpty \- terminal utility functions
+.SH LIBRARY
+System utilities library
+.RI ( libutil ", " \-lutil )
+.SH SYNOPSIS
+.nf
+.B #include <pty.h>
+.P
+.BI "int openpty(int *" amaster ", int *" aslave ", char *" name ,
+.BI "              const struct termios *" termp ,
+.BI "              const struct winsize *" winp );
+.BI "pid_t forkpty(int *" amaster ", char *" name ,
+.BI "              const struct termios *" termp ,
+.BI "              const struct winsize *" winp );
+.P
+.B #include <utmp.h>
+.P
+.BI "int login_tty(int " fd );
+.fi
+.SH DESCRIPTION
+The
+.BR openpty ()
+function finds an available pseudoterminal and returns file descriptors
+for the master and slave in
+.I amaster
+and
+.IR aslave .
+If
+.I name
+is not NULL, the filename of the slave is returned in
+.IR name .
+If
+.I termp
+is not NULL, the terminal parameters of the slave will be set to the
+values in
+.IR termp .
+If
+.I winp
+is not NULL, the window size of the slave will be set to the values in
+.IR winp .
+.P
+The
+.BR login_tty ()
+function prepares for a login on the terminal
+referred to by the file descriptor
+.I fd
+(which may be a real terminal device, or the slave of a pseudoterminal as
+returned by
+.BR openpty ())
+by creating a new session, making
+.I fd
+the controlling terminal for the calling process, setting
+.I fd
+to be the standard input, output, and error streams of the current
+process, and closing
+.IR fd .
+.P
+The
+.BR forkpty ()
+function combines
+.BR openpty (),
+.BR fork (2),
+and
+.BR login_tty ()
+to create a new process operating in a pseudoterminal.
+A file descriptor referring to
+master side of the pseudoterminal is returned in
+.IR amaster .
+If
+.I name
+is not NULL, the buffer it points to is used to return the
+filename of the slave.
+The
+.I termp
+and
+.I winp
+arguments, if not NULL,
+will determine the terminal attributes and window size of the slave
+side of the pseudoterminal.
+.SH RETURN VALUE
+If a call to
+.BR openpty (),
+.BR login_tty (),
+or
+.BR forkpty ()
+is not successful, \-1 is returned and
+.I errno
+is set to indicate the error.
+Otherwise,
+.BR openpty (),
+.BR login_tty (),
+and the child process of
+.BR forkpty ()
+return 0, and the parent process of
+.BR forkpty ()
+returns the process ID of the child process.
+.SH ERRORS
+.BR openpty ()
+fails if:
+.TP
+.B ENOENT
+There are no available terminals.
+.P
+.BR login_tty ()
+fails if
+.BR ioctl (2)
+fails to set
+.I fd
+to the controlling terminal of the calling process.
+.P
+.BR forkpty ()
+fails if either
+.BR openpty ()
+or
+.BR fork (2)
+fails.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR forkpty (),
+.BR openpty ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR login_tty ()
+T}	Thread safety	MT-Unsafe race:ttyname
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+The
+.B const
+modifiers were added to the structure pointer arguments of
+.BR openpty ()
+and
+.BR forkpty ()
+in glibc 2.8.
+.P
+Before glibc 2.0.92,
+.BR openpty ()
+returns file descriptors for a BSD pseudoterminal pair;
+since glibc 2.0.92,
+it first attempts to open a UNIX 98 pseudoterminal pair,
+and falls back to opening a BSD pseudoterminal pair if that fails.
+.SH BUGS
+Nobody knows how much space should be reserved for
+.IR name .
+So, calling
+.BR openpty ()
+or
+.BR forkpty ()
+with non-NULL
+.I name
+may not be secure.
+.SH SEE ALSO
+.BR fork (2),
+.BR ttyname (3),
+.BR pty (7)
diff --git a/man/man3/optarg.3 b/man/man3/optarg.3
new file mode 100644
index 000000000..7612d3f67
--- /dev/null
+++ b/man/man3/optarg.3
@@ -0,0 +1 @@
+.so man3/getopt.3
diff --git a/man/man3/opterr.3 b/man/man3/opterr.3
new file mode 100644
index 000000000..7612d3f67
--- /dev/null
+++ b/man/man3/opterr.3
@@ -0,0 +1 @@
+.so man3/getopt.3
diff --git a/man/man3/optind.3 b/man/man3/optind.3
new file mode 100644
index 000000000..7612d3f67
--- /dev/null
+++ b/man/man3/optind.3
@@ -0,0 +1 @@
+.so man3/getopt.3
diff --git a/man/man3/optopt.3 b/man/man3/optopt.3
new file mode 100644
index 000000000..7612d3f67
--- /dev/null
+++ b/man/man3/optopt.3
@@ -0,0 +1 @@
+.so man3/getopt.3
diff --git a/man/man3/passwd2des.3 b/man/man3/passwd2des.3
new file mode 100644
index 000000000..01b6ce65a
--- /dev/null
+++ b/man/man3/passwd2des.3
@@ -0,0 +1 @@
+.so man3/xcrypt.3
diff --git a/man/man3/pathconf.3 b/man/man3/pathconf.3
new file mode 100644
index 000000000..46d8c8b17
--- /dev/null
+++ b/man/man3/pathconf.3
@@ -0,0 +1 @@
+.so man3/fpathconf.3
diff --git a/man/man3/pclose.3 b/man/man3/pclose.3
new file mode 100644
index 000000000..663d4a081
--- /dev/null
+++ b/man/man3/pclose.3
@@ -0,0 +1 @@
+.so man3/popen.3
diff --git a/man/man3/perror.3 b/man/man3/perror.3
new file mode 100644
index 000000000..87a2520f1
--- /dev/null
+++ b/man/man3/perror.3
@@ -0,0 +1,142 @@
+'\" t
+.\" Copyright (c) 1994 Michael Haardt (michael@moria.de), 1994-06-04
+.\" Copyright (c) 1995 Michael Haardt
+.\"      (michael@cantor.informatik.rwth-aachen.de), 1995-03-16
+.\" Copyright (c) 1996 Andries Brouwer (aeb@cwi.nl), 1996-01-13
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1996-01-13 aeb: merged in some text contributed by Melvin Smith
+.\"   (msmith@falcon.mercer.peachnet.edu) and various other changes.
+.\" Modified 1996-05-16 by Martin Schulze (joey@infodrom.north.de)
+.\"
+.TH perror 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+perror \- print a system error message
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "void perror(const char *" s );
+.P
+.B #include <errno.h>
+.P
+.BI "int " errno ";       \fR/* Not really declared this way; see errno(3) */"
+.P
+.BI "[[deprecated]] const char *const " sys_errlist [];
+.BI "[[deprecated]] int " sys_nerr ;
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.IR sys_errlist ,
+.IR sys_nerr :
+.nf
+    From glibc 2.19 to glibc 2.31:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR perror ()
+function produces a message on standard error describing the last
+error encountered during a call to a system or library function.
+.P
+First (if
+.I s
+is not NULL and
+.I *s
+is not a null byte (\[aq]\e0\[aq])), the argument string
+.I s
+is printed, followed by a colon and a blank.
+Then an error message corresponding to the current value of
+.I errno
+and a new-line.
+.P
+To be of most use, the argument string should include the name
+of the function that incurred the error.
+.P
+The global error list
+.IR sys_errlist "[],"
+which can be indexed by
+.IR errno ,
+can be used to obtain the error message without the newline.
+The largest message number provided in the table is
+.IR sys_nerr "\-1."
+Be careful when directly accessing this list, because new error values
+may not have been added to
+.IR sys_errlist "[]."
+The use of
+.IR sys_errlist "[]"
+is nowadays deprecated; use
+.BR strerror (3)
+instead.
+.P
+When a system call fails, it usually returns \-1 and sets the
+variable
+.I errno
+to a value describing what went wrong.
+(These values can be found in
+.IR <errno.h> .)
+Many library functions do likewise.
+The function
+.BR perror ()
+serves to translate this error code into human-readable form.
+Note that
+.I errno
+is undefined after a successful system call or library function call:
+this call may well change this variable, even though it succeeds,
+for example because it internally used some other library function that failed.
+Thus, if a failing call is not immediately followed by a call to
+.BR perror (),
+the value of
+.I errno
+should be saved.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR perror ()
+T}	Thread safety	MT-Safe race:stderr
+.TE
+.SH STANDARDS
+.TP
+.I errno
+.TQ
+.BR perror ()
+C11, POSIX.1-2008.
+.TP
+.I sys_nerr
+.TQ
+.I sys_errlist
+BSD.
+.SH HISTORY
+.TP
+.I errno
+.TQ
+.BR perror ()
+POSIX.1-2001, C89, 4.3BSD.
+.TP
+.I sys_nerr
+.TQ
+.I sys_errlist
+Removed in glibc 2.32.
+.SH SEE ALSO
+.BR err (3),
+.BR errno (3),
+.BR error (3),
+.BR strerror (3)
diff --git a/man/man3/pmap_getmaps.3 b/man/man3/pmap_getmaps.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/pmap_getmaps.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/pmap_getport.3 b/man/man3/pmap_getport.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/pmap_getport.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/pmap_rmtcall.3 b/man/man3/pmap_rmtcall.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/pmap_rmtcall.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/pmap_set.3 b/man/man3/pmap_set.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/pmap_set.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/pmap_unset.3 b/man/man3/pmap_unset.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/pmap_unset.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/popen.3 b/man/man3/popen.3
new file mode 100644
index 000000000..c56d938e4
--- /dev/null
+++ b/man/man3/popen.3
@@ -0,0 +1,208 @@
+'\" t
+.\" Copyright 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)popen.3	6.4 (Berkeley) 4/30/91
+.\"
+.\" Converted for Linux, Mon Nov 29 14:45:38 1993, faith@cs.unc.edu
+.\" Modified Sat May 18 20:37:44 1996 by Martin Schulze (joey@linux.de)
+.\" Modified 7 May 1998 by Joseph S. Myers (jsm28@cam.ac.uk)
+.\"
+.TH popen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+popen, pclose \- pipe stream to or from a process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "FILE *popen(const char *" command ", const char *" type );
+.BI "int pclose(FILE *" stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR popen (),
+.BR pclose ():
+.nf
+    _POSIX_C_SOURCE >= 2
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR popen ()
+function opens a process by creating a pipe, forking, and invoking the
+shell.
+Since a pipe is by definition unidirectional, the
+.I type
+argument may specify only reading or writing, not both; the resulting
+stream is correspondingly read-only or write-only.
+.P
+The
+.I command
+argument is a pointer to a null-terminated string containing a shell
+command line.
+This command is passed to
+.I /bin/sh
+using the
+.B \-c
+flag; interpretation, if any, is performed by the shell.
+.P
+The
+.I type
+argument is a pointer to a null-terminated string which must contain
+either the letter \[aq]r\[aq] for reading or the letter \[aq]w\[aq] for writing.
+Since glibc 2.9,
+this argument can additionally include the letter \[aq]e\[aq],
+which causes the close-on-exec flag
+.RB ( FD_CLOEXEC )
+to be set on the underlying file descriptor;
+see the description of the
+.B O_CLOEXEC
+flag in
+.BR open (2)
+for reasons why this may be useful.
+.P
+The return value from
+.BR popen ()
+is a normal standard I/O stream in all respects save that it must be closed
+with
+.BR pclose ()
+rather than
+.BR fclose (3).
+Writing to such a stream writes to the standard input of the command; the
+command's standard output is the same as that of the process that called
+.BR popen (),
+unless this is altered by the command itself.
+Conversely, reading from
+the stream reads the command's standard output, and the command's
+standard input is the same as that of the process that called
+.BR popen ().
+.P
+Note that output
+.BR popen ()
+streams are block buffered by default.
+.P
+The
+.BR pclose ()
+function waits for the associated process to terminate and returns the exit
+status of the command as returned by
+.BR wait4 (2).
+.SH RETURN VALUE
+.BR popen ():
+on success, returns a pointer to an open stream that
+can be used to read or write to the pipe;
+if the
+.BR fork (2)
+or
+.BR pipe (2)
+calls fail, or if the function cannot allocate memory,
+NULL is returned.
+.P
+.BR pclose ():
+on success, returns the exit status of the command; if
+.\" These conditions actually give undefined results, so I commented
+.\" them out.
+.\" .I stream
+.\" is not associated with a "popen()ed" command, if
+.\".I stream
+.\" already "pclose()d", or if
+.BR wait4 (2)
+returns an error, or some other error is detected,
+\-1 is returned.
+.P
+On failure, both functions set
+.I errno
+to indicate the error.
+.SH ERRORS
+The
+.BR popen ()
+function does not set
+.I errno
+if memory allocation fails.
+If the underlying
+.BR fork (2)
+or
+.BR pipe (2)
+fails,
+.I errno
+is set to indicate the error.
+If the
+.I type
+argument is invalid, and this condition is detected,
+.I errno
+is set to
+.BR EINVAL .
+.P
+If
+.BR pclose ()
+cannot obtain the child status,
+.I errno
+is set to
+.BR ECHILD .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR popen (),
+.BR pclose ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The \[aq]e\[aq] value for
+.I type
+is a Linux extension.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH CAVEATS
+Carefully read Caveats in
+.BR system (3).
+.SH BUGS
+Since the standard input of a command opened for reading shares its seek
+offset with the process that called
+.BR popen (),
+if the original process has done a buffered read, the command's input
+position may not be as expected.
+Similarly, the output from a command
+opened for writing may become intermingled with that of the original
+process.
+The latter can be avoided by calling
+.BR fflush (3)
+before
+.BR popen ().
+.P
+Failure to execute the shell is indistinguishable from the shell's failure
+to execute the command, or an immediate exit of the command.
+The only hint is an exit status of 127.
+.\" .SH HISTORY
+.\" A
+.\" .BR popen ()
+.\" and a
+.\" .BR pclose ()
+.\" function appeared in Version 7 AT&T UNIX.
+.SH SEE ALSO
+.BR sh (1),
+.BR fork (2),
+.BR pipe (2),
+.BR wait4 (2),
+.BR fclose (3),
+.BR fflush (3),
+.BR fopen (3),
+.BR stdio (3),
+.BR system (3)
diff --git a/man/man3/posix_fallocate.3 b/man/man3/posix_fallocate.3
new file mode 100644
index 000000000..46ce6ac7f
--- /dev/null
+++ b/man/man3/posix_fallocate.3
@@ -0,0 +1,181 @@
+'\" t
+.\" Copyright (c) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH posix_fallocate 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+posix_fallocate \- allocate file space
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <fcntl.h>
+.P
+.BI "int posix_fallocate(int " fd ", off_t " offset ", off_t " len );
+.fi
+.P
+.ad l
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR posix_fallocate ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The function
+.BR posix_fallocate ()
+ensures that disk space is allocated for the file referred to by the
+file descriptor
+.I fd
+for the bytes in the range starting at
+.I offset
+and continuing for
+.I len
+bytes.
+After a successful call to
+.BR posix_fallocate (),
+subsequent writes to bytes in the specified range are
+guaranteed not to fail because of lack of disk space.
+.P
+If the size of the file is less than
+.IR offset + len ,
+then the file is increased to this size;
+otherwise the file size is left unchanged.
+.SH RETURN VALUE
+.BR posix_fallocate ()
+returns zero on success, or an error number on failure.
+Note that
+.I errno
+is not set.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor, or is not opened for writing.
+.TP
+.B EFBIG
+.I offset+len
+exceeds the maximum file size.
+.TP
+.B EINTR
+A signal was caught during execution.
+.TP
+.B EINVAL
+.I offset
+was less than 0, or
+.I len
+was less than or equal to 0, or the underlying filesystem does not
+support the operation.
+.TP
+.B ENODEV
+.I fd
+does not refer to a regular file.
+.TP
+.B ENOSPC
+There is not enough space left on the device containing the file
+referred to by
+.IR fd .
+.TP
+.B EOPNOTSUPP
+The filesystem containing the file referred to by
+.I fd
+does not support this operation.
+This error code can be returned by C libraries that don't perform the
+emulation shown in NOTES, such as musl libc.
+.TP
+.B ESPIPE
+.I fd
+refers to a pipe.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR posix_fallocate ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe (but see NOTES)
+T}
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.94.
+POSIX.1-2001
+.P
+POSIX.1-2008 says that an implementation
+.I shall
+give the
+.B EINVAL
+error if
+.I len
+was 0, or
+.I offset
+was less than 0.
+POSIX.1-2001 says that an implementation
+.I shall
+give the
+.B EINVAL
+error if
+.I len
+is less than 0, or
+.I offset
+was less than 0, and
+.I may
+give the error if
+.I len
+equals zero.
+.SH CAVEATS
+In the glibc implementation,
+.BR posix_fallocate ()
+is implemented using the
+.BR fallocate (2)
+system call, which is MT-safe.
+If the underlying filesystem does not support
+.BR fallocate (2),
+then the operation is emulated with the following caveats:
+.IP \[bu] 3
+The emulation is inefficient.
+.IP \[bu]
+There is a race condition where concurrent writes from another thread or
+process could be overwritten with null bytes.
+.IP \[bu]
+There is a race condition where concurrent file size increases by
+another thread or process could result in a file whose size is smaller
+than expected.
+.IP \[bu]
+If
+.I fd
+has been opened with the
+.B O_APPEND
+or
+.B O_WRONLY
+flags, the function fails with the error
+.BR EBADF .
+.P
+In general, the emulation is not MT-safe.
+On Linux, applications may use
+.BR fallocate (2)
+if they cannot tolerate the emulation caveats.
+In general, this is
+only recommended if the application plans to terminate the operation if
+.B EOPNOTSUPP
+is returned, otherwise the application itself will need to implement a
+fallback with all the same problems as the emulation provided by glibc.
+.SH SEE ALSO
+.BR fallocate (1),
+.BR fallocate (2),
+.BR lseek (2),
+.BR posix_fadvise (2)
diff --git a/man/man3/posix_madvise.3 b/man/man3/posix_madvise.3
new file mode 100644
index 000000000..967d52aec
--- /dev/null
+++ b/man/man3/posix_madvise.3
@@ -0,0 +1,112 @@
+.\" Copyright (C) 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH posix_madvise 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+posix_madvise \- give advice about patterns of memory usage
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.P
+.BI "int posix_madvise(void " addr [. len "], size_t " len ", int " advice );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR posix_madvise ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR posix_madvise ()
+function allows an application to advise the system about its expected
+patterns of usage of memory in the address range starting at
+.I addr
+and continuing for
+.I len
+bytes.
+The system is free to use this advice in order to improve the performance
+of memory accesses (or to ignore the advice altogether), but calling
+.BR posix_madvise ()
+shall not affect the semantics of access to memory in the specified range.
+.P
+The
+.I advice
+argument is one of the following:
+.TP
+.B POSIX_MADV_NORMAL
+The application has no special advice regarding its memory usage patterns
+for the specified address range.
+This is the default behavior.
+.TP
+.B POSIX_MADV_SEQUENTIAL
+The application expects to access the specified address range sequentially,
+running from lower addresses to higher addresses.
+Hence, pages in this region can be aggressively read ahead,
+and may be freed soon after they are accessed.
+.TP
+.B POSIX_MADV_RANDOM
+The application expects to access the specified address range randomly.
+Thus, read ahead may be less useful than normally.
+.TP
+.B POSIX_MADV_WILLNEED
+The application expects to access the specified address range
+in the near future.
+Thus, read ahead may be beneficial.
+.TP
+.B POSIX_MADV_DONTNEED
+The application expects that it will not access the specified address range
+in the near future.
+.SH RETURN VALUE
+On success,
+.BR posix_madvise ()
+returns 0.
+On failure, it returns a positive error number.
+.SH ERRORS
+.TP
+.B EINVAL
+.I addr
+is not a multiple of the system page size or
+.I len
+is negative.
+.TP
+.B EINVAL
+.I advice
+is invalid.
+.TP
+.B ENOMEM
+Addresses in the specified range are partially or completely outside
+the caller's address space.
+.SH VERSIONS
+POSIX.1 permits an implementation to generate an error if
+.I len
+is 0.
+On Linux, specifying
+.I len
+as 0 is permitted (as a successful no-op).
+.P
+In glibc, this function is implemented using
+.BR madvise (2).
+However, since glibc 2.6,
+.B POSIX_MADV_DONTNEED
+is treated as a no-op, because the corresponding
+.BR madvise (2)
+value,
+.BR MADV_DONTNEED ,
+has destructive semantics.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.SH SEE ALSO
+.BR madvise (2),
+.BR posix_fadvise (2)
diff --git a/man/man3/posix_memalign.3 b/man/man3/posix_memalign.3
new file mode 100644
index 000000000..534f85932
--- /dev/null
+++ b/man/man3/posix_memalign.3
@@ -0,0 +1,276 @@
+'\" t
+.\" Copyright (c) 2001 by John Levon <moz@compsoc.man.ac.uk>
+.\" Based in part on GNU libc documentation.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2001-10-11, 2003-08-22, aeb, added some details
+.\" 2012-03-23, Michael Kerrisk <mtk.manpages@mail.com>
+.\"     Document pvalloc() and aligned_alloc()
+.TH posix_memalign 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+posix_memalign, aligned_alloc, memalign, valloc, pvalloc \-
+allocate aligned memory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int posix_memalign(void **" memptr ", size_t " alignment ", size_t " size );
+.BI "void *aligned_alloc(size_t " alignment ", size_t " size );
+.BI "[[deprecated]] void *valloc(size_t " size );
+.P
+.B #include <malloc.h>
+.P
+.BI "[[deprecated]] void *memalign(size_t " alignment ", size_t " size );
+.BI "[[deprecated]] void *pvalloc(size_t " size );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR posix_memalign ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.P
+.BR aligned_alloc ():
+.nf
+    _ISOC11_SOURCE
+.fi
+.P
+.BR valloc ():
+.nf
+    Since glibc 2.12:
+        (_XOPEN_SOURCE >= 500) && !(_POSIX_C_SOURCE >= 200112L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+    Before glibc 2.12:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+.BR posix_memalign ()
+allocates
+.I size
+bytes and places the address of the allocated memory in
+.IR "*memptr" .
+The address of the allocated memory will be a multiple of
+.IR "alignment" ,
+which must be a power of two and a multiple of
+.IR "sizeof(void\ *)" .
+This address can later be successfully passed to
+.BR free (3).
+If
+.I size
+is 0, then
+the value placed in
+.I *memptr
+is either NULL
+.\" glibc does this:
+or a unique pointer value.
+.P
+The obsolete function
+.BR memalign ()
+allocates
+.I size
+bytes and returns a pointer to the allocated memory.
+The memory address will be a multiple of
+.IR alignment ,
+which must be a power of two.
+.\" The behavior of memalign() for size==0 is as for posix_memalign()
+.\" but no standards govern this.
+.P
+.BR aligned_alloc ()
+is the same as
+.BR memalign (),
+except for the added restriction that
+.I alignment
+must be a power of two.
+.P
+The obsolete function
+.BR valloc ()
+allocates
+.I size
+bytes and returns a pointer to the allocated memory.
+The memory address will be a multiple of the page size.
+It is equivalent to
+.IR "memalign(sysconf(_SC_PAGESIZE),size)" .
+.P
+The obsolete function
+.BR pvalloc ()
+is similar to
+.BR valloc (),
+but rounds the size of the allocation up to
+the next multiple of the system page size.
+.P
+For all of these functions, the memory is not zeroed.
+.SH RETURN VALUE
+.BR aligned_alloc (),
+.BR memalign (),
+.BR valloc (),
+and
+.BR pvalloc ()
+return a pointer to the allocated memory on success.
+On error, NULL is returned, and \fIerrno\fP is set
+to indicate the error.
+.P
+.BR posix_memalign ()
+returns zero on success, or one of the error values listed in the
+next section on failure.
+The value of
+.I errno
+is not set.
+On Linux (and other systems),
+.BR posix_memalign ()
+does not modify
+.I memptr
+on failure.
+A requirement standardizing this behavior was added in POSIX.1-2008 TC2.
+.\" http://austingroupbugs.net/view.php?id=520
+.SH ERRORS
+.TP
+.B EINVAL
+The
+.I alignment
+argument was not a power of two, or was not a multiple of
+.IR "sizeof(void\ *)" .
+.TP
+.B ENOMEM
+Out of memory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR aligned_alloc (),
+.BR memalign (),
+.BR posix_memalign ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR valloc (),
+.BR pvalloc ()
+T}	Thread safety	MT-Unsafe init
+.TE
+.SH STANDARDS
+.TP
+.BR aligned_alloc ()
+C11.
+.TP
+.BR posix_memalign ()
+POSIX.1-2008.
+.TP
+.BR memalign ()
+.TQ
+.BR valloc ()
+None.
+.TP
+.BR pvalloc ()
+GNU.
+.SH HISTORY
+.TP
+.BR aligned_alloc ()
+glibc 2.16.
+C11.
+.TP
+.BR posix_memalign ()
+glibc 2.1.91.
+POSIX.1d, POSIX.1-2001.
+.TP
+.BR memalign ()
+glibc 2.0.
+SunOS 4.1.3.
+.TP
+.BR valloc ()
+glibc 2.0.
+3.0BSD.
+Documented as obsolete in 4.3BSD,
+and as legacy in SUSv2.
+.TP
+.BR pvalloc ()
+glibc 2.0.
+.\"
+.SS Headers
+Everybody agrees that
+.BR posix_memalign ()
+is declared in \fI<stdlib.h>\fP.
+.P
+On some systems
+.BR memalign ()
+is declared in \fI<stdlib.h>\fP instead of \fI<malloc.h>\fP.
+.P
+According to SUSv2,
+.BR valloc ()
+is declared in \fI<stdlib.h>\fP.
+.\" Libc4,5 and
+glibc declares it in \fI<malloc.h>\fP, and also in
+\fI<stdlib.h>\fP
+if suitable feature test macros are defined (see above).
+.SH NOTES
+On many systems there are alignment restrictions, for example, on buffers
+used for direct block device I/O.
+POSIX specifies the
+.I "pathconf(path,_PC_REC_XFER_ALIGN)"
+call that tells what alignment is needed.
+Now one can use
+.BR posix_memalign ()
+to satisfy this requirement.
+.P
+.BR posix_memalign ()
+verifies that
+.I alignment
+matches the requirements detailed above.
+.BR memalign ()
+may not check that the
+.I alignment
+argument is correct.
+.P
+POSIX requires that memory obtained from
+.BR posix_memalign ()
+can be freed using
+.BR free (3).
+Some systems provide no way to reclaim memory allocated with
+.BR memalign ()
+or
+.BR valloc ()
+(because one can pass to
+.BR free (3)
+only a pointer obtained from
+.BR malloc (3),
+while, for example,
+.BR memalign ()
+would call
+.BR malloc (3)
+and then align the obtained value).
+.\" Other systems allow passing the result of
+.\" .IR valloc ()
+.\" to
+.\" .IR free (3),
+.\" but not to
+.\" .IR realloc (3).
+The glibc implementation
+allows memory obtained from any of these functions to be
+reclaimed with
+.BR free (3).
+.P
+The glibc
+.BR malloc (3)
+always returns 8-byte aligned memory addresses, so these functions are
+needed only if you require larger alignment values.
+.SH SEE ALSO
+.BR brk (2),
+.BR getpagesize (2),
+.BR free (3),
+.BR malloc (3)
diff --git a/man/man3/posix_openpt.3 b/man/man3/posix_openpt.3
new file mode 100644
index 000000000..496b38d67
--- /dev/null
+++ b/man/man3/posix_openpt.3
@@ -0,0 +1,107 @@
+'\" t
+.\" Copyright (C) 2004 Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH posix_openpt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+posix_openpt \- open a pseudoterminal device
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.B #include <fcntl.h>
+.P
+.BI "int posix_openpt(int " flags ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR posix_openpt ():
+.nf
+    _XOPEN_SOURCE >= 600
+.fi
+.SH DESCRIPTION
+The
+.BR posix_openpt ()
+function opens an unused pseudoterminal master device, returning a
+file descriptor that can be used to refer to that device.
+.P
+The
+.I flags
+argument is a bit mask that ORs together zero or more of
+the following flags:
+.TP
+.B O_RDWR
+Open the device for both reading and writing.
+It is usual to specify this flag.
+.TP
+.B O_NOCTTY
+Do not make this device the controlling terminal for the process.
+.SH RETURN VALUE
+On success,
+.BR posix_openpt ()
+returns a file descriptor (a nonnegative integer) which is the lowest
+numbered unused file descriptor.
+On failure, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+See
+.BR open (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR posix_openpt ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.1.
+POSIX.1-2001.
+.P
+It is part of the UNIX 98 pseudoterminal support (see
+.BR pts (4)).
+.SH NOTES
+Some older UNIX implementations that support System V
+(aka UNIX 98) pseudoterminals don't have this function, but it
+can be easily implemented by opening the pseudoterminal multiplexor device:
+.P
+.in +4n
+.EX
+int
+posix_openpt(int flags)
+{
+    return open("/dev/ptmx", flags);
+}
+.EE
+.in
+.P
+Calling
+.BR posix_openpt ()
+creates a pathname for the corresponding pseudoterminal slave device.
+The pathname of the slave device can be obtained using
+.BR ptsname (3).
+The slave device pathname exists only as long as the master device is open.
+.SH SEE ALSO
+.BR open (2),
+.BR getpt (3),
+.BR grantpt (3),
+.BR ptsname (3),
+.BR unlockpt (3),
+.BR pts (4),
+.BR pty (7)
diff --git a/man/man3/posix_spawn.3 b/man/man3/posix_spawn.3
new file mode 100644
index 000000000..7eb96429f
--- /dev/null
+++ b/man/man3/posix_spawn.3
@@ -0,0 +1,823 @@
+.\" Copyright (c) 2009 Bill O. Gallmeister (bgallmeister@gmail.com)
+.\" and Copyright 2010 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux glibc source code
+.\"     POSIX 1003.1-2004 documentation
+.\"     (http://www.opengroup.org/onlinepubs/009695399)
+.\"
+.TH posix_spawn 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+posix_spawn, posix_spawnp \- spawn a process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <spawn.h>
+.P
+.BI "int posix_spawn(pid_t *restrict " pid ", const char *restrict " path ,
+.BI "                const posix_spawn_file_actions_t *restrict " file_actions ,
+.BI "                const posix_spawnattr_t *restrict " attrp ,
+.BI "                char *const " argv [restrict],
+.BI "                char *const " envp [restrict]);
+.BI "int posix_spawnp(pid_t *restrict " pid ", const char *restrict " file ,
+.BI "                const posix_spawn_file_actions_t *restrict " file_actions ,
+.BI "                const posix_spawnattr_t *restrict " attrp ,
+.BI "                char *const " argv [restrict],
+.BI "                char *const " envp [restrict]);
+.fi
+.SH DESCRIPTION
+The
+.BR posix_spawn ()
+and
+.BR posix_spawnp ()
+functions are used to create a new child process that executes
+a specified file.
+These functions were specified by POSIX to provide a standardized method
+of creating new processes on machines that lack the capability
+to support the
+.BR fork (2)
+system call.
+These machines are generally small, embedded systems lacking MMU support.
+.P
+The
+.BR posix_spawn ()
+and
+.BR posix_spawnp ()
+functions provide the functionality of a combined
+.BR fork (2)
+and
+.BR exec (3),
+with some optional housekeeping steps in the child process before the
+.BR exec (3).
+These functions are not meant to replace the
+.BR fork (2)
+and
+.BR execve (2)
+system calls.
+In fact, they provide only a subset of the functionality
+that can be achieved by using the system calls.
+.P
+The only difference between
+.BR posix_spawn ()
+and
+.BR posix_spawnp ()
+is the manner in which they specify the file to be executed by
+the child process.
+With
+.BR posix_spawn (),
+the executable file is specified as a pathname
+(which can be absolute or relative).
+With
+.BR posix_spawnp (),
+the executable file is specified as a simple filename;
+the system searches for this file in the list of directories specified by
+.B PATH
+(in the same way as for
+.BR execvp (3)).
+For the remainder of this page, the discussion is phrased in terms of
+.BR posix_spawn (),
+with the understanding that
+.BR posix_spawnp ()
+differs only on the point just described.
+.P
+The remaining arguments to these two functions are as follows:
+.TP
+.I pid
+points to a buffer that is used to return the process ID
+of the new child process.
+.TP
+.I file_actions
+points to a
+.I "spawn file actions object"
+that specifies file-related actions to be performed in the child
+between the
+.BR fork (2)
+and
+.BR exec (3)
+steps.
+This object is initialized and populated before the
+.BR posix_spawn ()
+call using
+.BR posix_spawn_file_actions_init (3)
+and the
+.BR posix_spawn_file_actions_* ()
+functions.
+.TP
+.I attrp
+points to an
+.I attributes objects
+that specifies various attributes of the created child process.
+This object is initialized and populated before the
+.BR posix_spawn ()
+call using
+.BR posix_spawnattr_init (3)
+and the
+.BR posix_spawnattr_* ()
+functions.
+.TP
+.I argv
+.TQ
+.I envp
+specify the argument list and environment for the program
+that is executed in the child process, as for
+.BR execve (2).
+.P
+Below, the functions are described in terms of a three-step process: the
+.BR fork ()
+step, the
+.RB pre- exec ()
+step (executed in the child),
+and the
+.BR exec ()
+step (executed in the child).
+.SS fork() step
+Since glibc 2.24, the
+.BR posix_spawn ()
+function commences by calling
+.BR clone (2)
+with
+.B CLONE_VM
+and
+.B CLONE_VFORK
+flags.
+Older implementations use
+.BR fork (2),
+or possibly
+.BR vfork (2)
+(see below).
+.P
+The PID of the new child process is placed in
+.IR *pid .
+The
+.BR posix_spawn ()
+function then returns control to the parent process.
+.P
+Subsequently, the parent can use one of the system calls described in
+.BR wait (2)
+to check the status of the child process.
+If the child fails in any of the housekeeping steps described below,
+or fails to execute the desired file,
+it exits with a status of 127.
+.P
+Before glibc 2.24, the child process is created using
+.BR vfork (2)
+instead of
+.BR fork (2)
+when either of the following is true:
+.IP \[bu] 3
+the
+.I spawn-flags
+element of the attributes object pointed to by
+.I attrp
+contains the GNU-specific flag
+.BR POSIX_SPAWN_USEVFORK ;
+or
+.IP \[bu]
+.I file_actions
+is NULL and the
+.I spawn-flags
+element of the attributes object pointed to by
+.I attrp
+does \fInot\fP contain
+.BR POSIX_SPAWN_SETSIGMASK ,
+.BR POSIX_SPAWN_SETSIGDEF ,
+.BR POSIX_SPAWN_SETSCHEDPARAM ,
+.BR POSIX_SPAWN_SETSCHEDULER ,
+.BR POSIX_SPAWN_SETPGROUP ,
+or
+.BR POSIX_SPAWN_RESETIDS .
+.P
+In other words,
+.BR vfork (2)
+is used if the caller requests it,
+or if there is no cleanup expected in the child before it
+.BR exec (3)s
+the requested file.
+.SS pre-exec() step: housekeeping
+In between the
+.B fork()
+and the
+.B exec()
+steps, a child process may need to perform a set of housekeeping actions.
+The
+.BR posix_spawn ()
+and
+.BR posix_spawnp ()
+functions support a small, well-defined set of system tasks that the child
+process can accomplish before it executes the executable file.
+These operations are controlled by the attributes object pointed to by
+.I attrp
+and the file actions object pointed to by
+.IR file_actions .
+In the child, processing is done in the following sequence:
+.IP (1) 5
+Process attribute actions: signal mask, signal default handlers,
+scheduling algorithm and parameters,
+process group, and effective user and group IDs
+are changed as specified by the attributes object pointed to by
+.IR attrp .
+.IP (2)
+File actions, as specified in the
+.I file_actions
+argument,
+are performed in the order that they were specified using calls to the
+.BR posix_spawn_file_actions_add* ()
+functions.
+.IP (3)
+File descriptors with the
+.B FD_CLOEXEC
+flag set are closed.
+.P
+All process attributes in the child,
+other than those affected by attributes specified in the
+object pointed to by
+.I attrp
+and the file actions in the object pointed to by
+.IR file_actions ,
+will be affected as though the child was created with
+.BR fork (2)
+and it executed the program with
+.BR execve (2).
+.P
+The process attributes actions are defined by the attributes object
+pointed to by
+.IR attrp .
+The
+.I spawn-flags
+attribute (set using
+.BR posix_spawnattr_setflags (3))
+controls the general actions that occur,
+and other attributes in the object specify values
+to be used during those actions.
+.P
+The effects of the flags that may be specified in
+.I spawn-flags
+are as follows:
+.TP
+.B POSIX_SPAWN_SETSIGMASK
+Set the signal mask to the signal set specified in the
+.I spawn-sigmask
+attribute
+.\" FIXME .
+.\" (see
+.\" .BR posix_spawnattr_setsigmask (3))
+of the object pointed to by
+.IR attrp .
+If the
+.B POSIX_SPAWN_SETSIGMASK
+flag is not set, then the child inherits the parent's signal mask.
+.TP
+.B POSIX_SPAWN_SETSIGDEF
+Reset the disposition of all signals in the set specified in the
+.I spawn-sigdefault
+attribute
+.\" FIXME .
+.\" (see
+.\" .BR posix_spawnattr_setsigdefault (3))
+of the object pointed to by
+.I attrp
+to the default.
+For the treatment of the dispositions of signals not specified in the
+.I spawn-sigdefault
+attribute, or the treatment when
+.B POSIX_SPAWN_SETSIGDEF
+is not specified, see
+.BR execve (2).
+.TP
+.B POSIX_SPAWN_SETSCHEDPARAM
+.\" (POSIX_PRIORITY_SCHEDULING only)
+If this flag is set, and the
+.B POSIX_SPAWN_SETSCHEDULER
+flag is not set, then set the scheduling parameters
+to the parameters specified in the
+.I spawn-schedparam
+attribute
+.\" FIXME .
+.\" (see
+.\" .BR posix_spawnattr_setschedparam (3))
+of the object pointed to by
+.IR attrp .
+.TP
+.B POSIX_SPAWN_SETSCHEDULER
+Set the scheduling policy algorithm and parameters of the child,
+as follows:
+.RS
+.IP \[bu] 3
+The scheduling policy is set to the value specified in the
+.I spawn-schedpolicy
+attribute
+.\" FIXME .
+.\" (see
+.\" .BR posix_spawnattr_setpolicy (3))
+of the object pointed to by
+.IR attrp .
+.IP \[bu]
+The scheduling parameters are set to the value specified in the
+.I spawn-schedparam
+attribute
+.\" FIXME .
+.\" (see
+.\" .BR posix_spawnattr_setschedparam (3))
+of the object pointed to by
+.I attrp
+(but see BUGS).
+.P
+If the
+.B POSIX_SPAWN_SETSCHEDPARAM
+and
+.B POSIX_SPAWN_SETSCHEDPOLICY
+flags are not specified,
+the child inherits the corresponding scheduling attributes from the parent.
+.RE
+.TP
+.B POSIX_SPAWN_RESETIDS
+If this flag is set,
+reset the effective UID and GID to the
+real UID and GID of the parent process.
+If this flag is not set,
+then the child retains the effective UID and GID of the parent.
+In either case, if the set-user-ID and set-group-ID permission
+bits are enabled on the executable file, their effect will override
+the setting of the effective UID and GID (se
+.BR execve (2)).
+.TP
+.B POSIX_SPAWN_SETPGROUP
+Set the process group to the value specified in the
+.I spawn-pgroup
+attribute
+.\" FIXME .
+.\" (see
+.\" .BR posix_spawnattr_setpgroup (3))
+of the object pointed to by
+.IR attrp .
+If the
+.I spawn-pgroup
+attribute has the value 0,
+the child's process group ID is made the same as its process ID.
+If the
+.B POSIX_SPAWN_SETPGROUP
+flag is not set, the child inherits the parent's process group ID.
+.TP
+.B POSIX_SPAWN_USEVFORK
+Since glibc 2.24, this flag has no effect.
+On older implementations, setting this flag forces the
+.B fork()
+step to use
+.BR vfork (2)
+instead of
+.BR fork (2).
+The
+.B _GNU_SOURCE
+feature test macro must be defined to obtain the definition of this constant.
+.TP
+.BR POSIX_SPAWN_SETSID " (since glibc 2.26)"
+If this flag is set,
+the child process shall create a new session and become the session leader.
+The child process shall also become the process group leader of the new process
+group in the session (see
+.BR setsid (2)).
+The
+.B _GNU_SOURCE
+feature test macro must be defined to obtain the definition of this constant.
+.\" This flag has been accepted in POSIX, see:
+.\" http://austingroupbugs.net/view.php?id=1044
+.\" and has been implemented since glibc 2.26
+.\" commit daeb1fa2e1b33323e719015f5f546988bd4cc73b
+.P
+If
+.I attrp
+is NULL, then the default behaviors described above for each flag apply.
+.\" mtk: I think we probably don't want to say the following, since it
+.\"      could lead people to do the wrong thing
+.\" The POSIX standard tells you to call
+.\" this function to de-initialize the attributes object pointed to by
+.\" .I attrp
+.\" when you are done with it;
+.\" however, on Linux systems this operation is a no-op.
+.P
+The
+.I file_actions
+argument specifies a sequence of file operations
+that are performed in the child process after
+the general processing described above, and before it performs the
+.BR exec (3).
+If
+.I file_actions
+is NULL, then no special action is taken, and standard
+.BR exec (3)
+semantics apply\[em]file descriptors open before the exec
+remain open in the new process,
+except those for which the
+.B FD_CLOEXEC
+flag has been set.
+File locks remain in place.
+.P
+If
+.I file_actions
+is not NULL, then it contains an ordered set of requests to
+.BR open (2),
+.BR close (2),
+and
+.BR dup2 (2)
+files.
+These requests are added to the
+.I file_actions
+by
+.BR posix_spawn_file_actions_addopen (3),
+.BR posix_spawn_file_actions_addclose (3),
+and
+.BR posix_spawn_file_actions_adddup2 (3).
+The requested operations are performed in the order they were added to
+.IR file_actions .
+.\" FIXME . I think the following is best placed in the
+.\" posix_spawn_file_actions_adddup2(3) page, and a similar statement is
+.\" also needed in posix_spawn_file_actions_addclose(3)
+.\" Note that you can specify file descriptors in
+.\" .I posix_spawn_file_actions_adddup2 (3)
+.\" which would not be usable if you called
+.\" .BR dup2 (2)
+.\" at that time--i.e., file descriptors that are opened or
+.\" closed by the earlier operations
+.\" added to
+.\" .I file_actions .
+.P
+If any of the housekeeping actions fails
+(due to bogus values being passed or other reasons why signal handling,
+process scheduling, process group ID functions,
+and file descriptor operations might fail),
+the child process exits with exit value 127.
+.SS exec() step
+Once the child has successfully forked and performed
+all requested pre-exec steps,
+the child runs the requested executable.
+.P
+The child process takes its environment from the
+.I envp
+argument, which is interpreted as if it had been passed to
+.BR execve (2).
+The arguments to the created process come from the
+.I argv
+argument, which is processed as for
+.BR execve (2).
+.SH RETURN VALUE
+Upon successful completion,
+.BR posix_spawn ()
+and
+.BR posix_spawnp ()
+place the PID of the child process in
+.IR pid ,
+and return 0.
+If there is an error during the
+.B fork()
+step,
+then no child is created,
+the contents of
+.I *pid
+are unspecified,
+and these functions return an error number as described below.
+.P
+Even when these functions return a success status,
+the child process may still fail for a plethora of reasons related to its
+pre-\fBexec\fR() initialization.
+In addition, the
+.BR exec (3)
+may fail.
+In all of these cases, the child process will exit with the exit value of 127.
+.SH ERRORS
+The
+.BR posix_spawn ()
+and
+.BR posix_spawnp ()
+functions fail only in the case where the underlying
+.BR fork (2),
+.BR vfork (2),
+or
+.BR clone (2)
+call fails;  in these cases, these functions return an error number,
+which will be one of the errors described for
+.BR fork (2),
+.BR vfork (2),
+or
+.BR clone (2).
+.P
+In addition, these functions fail if:
+.TP
+.B ENOSYS
+Function not supported on this system.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.\" FIXME . This piece belongs in spawnattr_setflags(3)
+.\" The
+.\" .B POSIX_SPAWN_USEVFORK
+.\" flag is a GNU extension; the
+.\" .B _GNU_SOURCE
+.\" feature test macro must be defined (before including any header files)
+.\" to obtain the definition of this constant.
+.SH NOTES
+The housekeeping activities in the child are controlled by
+the objects pointed to by
+.I attrp
+(for non-file actions) and
+.I file_actions
+In POSIX parlance, the
+.I posix_spawnattr_t
+and
+.I posix_spawn_file_actions_t
+data types are referred to as objects,
+and their elements are not specified by name.
+Portable programs should initialize these objects using
+only the POSIX-specified functions.
+(In other words,
+although these objects may be implemented as structures containing fields,
+portable programs must avoid dependence on such implementation details.)
+.P
+According to POSIX, it is unspecified whether fork handlers established with
+.BR pthread_atfork (3)
+are called when
+.BR posix_spawn ()
+is invoked.
+Since glibc 2.24, the fork handlers are not executed in any case.
+.\" Tested on glibc 2.12
+On older implementations,
+fork handlers are called only if the child is created using
+.BR fork (2).
+.P
+There is no "posix_fspawn" function (i.e., a function that is to
+.BR posix_spawn ()
+as
+.BR fexecve (3)
+is to
+.BR execve (2)).
+However, this functionality can be obtained by specifying the
+.I path
+argument as one of the files in the caller's
+.I /proc/self/fd
+directory.
+.SH BUGS
+POSIX.1 says that when
+.B POSIX_SPAWN_SETSCHEDULER
+is specified in
+.IR spawn-flags ,
+then the
+.B POSIX_SPAWN_SETSCHEDPARAM
+(if present) is ignored.
+However, before glibc 2.14, calls to
+.BR posix_spawn ()
+failed with an error if
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=12052
+.B POSIX_SPAWN_SETSCHEDULER
+was specified without also specifying
+.BR POSIX_SPAWN_SETSCHEDPARAM .
+.SH EXAMPLES
+The program below demonstrates the use of various functions in the
+POSIX spawn API.
+The program accepts command-line attributes that can be used
+to create file actions and attributes objects.
+The remaining command-line arguments are used as the executable name
+and command-line arguments of the program that is executed in the child.
+.P
+In the first run, the
+.BR date (1)
+command is executed in the child, and the
+.BR posix_spawn ()
+call employs no file actions or attributes objects.
+.P
+.in +4n
+.EX
+$ \fB./a.out date\fP
+PID of child: 7634
+Tue Feb  1 19:47:50 CEST 2011
+Child status: exited, status=0
+.EE
+.in
+.P
+In the next run, the
+.I \-c
+command-line option is used to create a file actions object that closes
+standard output in the child.
+Consequently,
+.BR date (1)
+fails when trying to perform output and exits with a status of 1.
+.P
+.in +4n
+.EX
+$ \fB./a.out \-c date\fP
+PID of child: 7636
+date: write error: Bad file descriptor
+Child status: exited, status=1
+.EE
+.in
+.P
+In the next run, the
+.I \-s
+command-line option is used to create an attributes object that
+specifies that all (blockable) signals in the child should be blocked.
+Consequently, trying to kill child with the default signal sent by
+.BR kill (1)
+(i.e.,
+.BR SIGTERM )
+fails, because that signal is blocked.
+Therefore, to kill the child,
+.B SIGKILL
+is necessary
+.RB ( SIGKILL
+can't be blocked).
+.P
+.in +4n
+.EX
+$ \fB./a.out \-s sleep 60 &\fP
+[1] 7637
+$ PID of child: 7638
+.P
+$ \fBkill 7638\fP
+$ \fBkill \-KILL 7638\fP
+$ Child status: killed by signal 9
+[1]+  Done                    ./a.out \-s sleep 60
+.EE
+.in
+.P
+When we try to execute a nonexistent command in the child, the
+.BR exec (3)
+fails and the child exits with a status of 127.
+.P
+.in +4n
+.EX
+$ \fB./a.out xxxxx
+PID of child: 10190
+Child status: exited, status=127
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (posix_spawn.c)
+.EX
+#include <errno.h>
+#include <spawn.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wait.h>
+\&
+#define errExit(msg)    do { perror(msg); \e
+                             exit(EXIT_FAILURE); } while (0)
+\&
+#define errExitEN(en, msg) \e
+                        do { errno = en; perror(msg); \e
+                             exit(EXIT_FAILURE); } while (0)
+\&
+char **environ;
+\&
+int
+main(int argc, char *argv[])
+{
+    pid_t child_pid;
+    int s, opt, status;
+    sigset_t mask;
+    posix_spawnattr_t attr;
+    posix_spawnattr_t *attrp;
+    posix_spawn_file_actions_t file_actions;
+    posix_spawn_file_actions_t *file_actionsp;
+\&
+    /* Parse command\-line options, which can be used to specify an
+       attributes object and file actions object for the child. */
+\&
+    attrp = NULL;
+    file_actionsp = NULL;
+\&
+    while ((opt = getopt(argc, argv, "sc")) != \-1) {
+        switch (opt) {
+        case \[aq]c\[aq]:       /* \-c: close standard output in child */
+\&
+            /* Create a file actions object and add a "close"
+               action to it. */
+\&
+            s = posix_spawn_file_actions_init(&file_actions);
+            if (s != 0)
+                errExitEN(s, "posix_spawn_file_actions_init");
+\&
+            s = posix_spawn_file_actions_addclose(&file_actions,
+                                                  STDOUT_FILENO);
+            if (s != 0)
+                errExitEN(s, "posix_spawn_file_actions_addclose");
+\&
+            file_actionsp = &file_actions;
+            break;
+\&
+        case \[aq]s\[aq]:       /* \-s: block all signals in child */
+\&
+            /* Create an attributes object and add a "set signal mask"
+               action to it. */
+\&
+            s = posix_spawnattr_init(&attr);
+            if (s != 0)
+                errExitEN(s, "posix_spawnattr_init");
+            s = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGMASK);
+            if (s != 0)
+                errExitEN(s, "posix_spawnattr_setflags");
+\&
+            sigfillset(&mask);
+            s = posix_spawnattr_setsigmask(&attr, &mask);
+            if (s != 0)
+                errExitEN(s, "posix_spawnattr_setsigmask");
+\&
+            attrp = &attr;
+            break;
+        }
+    }
+\&
+    /* Spawn the child. The name of the program to execute and the
+       command\-line arguments are taken from the command\-line arguments
+       of this program. The environment of the program execed in the
+       child is made the same as the parent\[aq]s environment. */
+\&
+    s = posix_spawnp(&child_pid, argv[optind], file_actionsp, attrp,
+                     &argv[optind], environ);
+    if (s != 0)
+        errExitEN(s, "posix_spawn");
+\&
+    /* Destroy any objects that we created earlier. */
+\&
+    if (attrp != NULL) {
+        s = posix_spawnattr_destroy(attrp);
+        if (s != 0)
+            errExitEN(s, "posix_spawnattr_destroy");
+    }
+\&
+    if (file_actionsp != NULL) {
+        s = posix_spawn_file_actions_destroy(file_actionsp);
+        if (s != 0)
+            errExitEN(s, "posix_spawn_file_actions_destroy");
+    }
+\&
+    printf("PID of child: %jd\en", (intmax_t) child_pid);
+\&
+    /* Monitor status of the child until it terminates. */
+\&
+    do {
+        s = waitpid(child_pid, &status, WUNTRACED | WCONTINUED);
+        if (s == \-1)
+            errExit("waitpid");
+\&
+        printf("Child status: ");
+        if (WIFEXITED(status)) {
+            printf("exited, status=%d\en", WEXITSTATUS(status));
+        } else if (WIFSIGNALED(status)) {
+            printf("killed by signal %d\en", WTERMSIG(status));
+        } else if (WIFSTOPPED(status)) {
+            printf("stopped by signal %d\en", WSTOPSIG(status));
+        } else if (WIFCONTINUED(status)) {
+            printf("continued\en");
+        }
+    } while (!WIFEXITED(status) && !WIFSIGNALED(status));
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.nh \" Disable hyphenation
+.ad l
+.BR close (2),
+.BR dup2 (2),
+.BR execl (2),
+.BR execlp (2),
+.BR fork (2),
+.BR open (2),
+.BR sched_setparam (2),
+.BR sched_setscheduler (2),
+.BR setpgid (2),
+.BR setuid (2),
+.BR sigaction (2),
+.BR sigprocmask (2),
+.BR posix_spawn_file_actions_addclose (3),
+.BR posix_spawn_file_actions_adddup2 (3),
+.BR posix_spawn_file_actions_addopen (3),
+.BR posix_spawn_file_actions_destroy (3),
+.BR posix_spawn_file_actions_init (3),
+.BR posix_spawnattr_destroy (3),
+.BR posix_spawnattr_getflags (3),
+.BR posix_spawnattr_getpgroup (3),
+.BR posix_spawnattr_getschedparam (3),
+.BR posix_spawnattr_getschedpolicy (3),
+.BR posix_spawnattr_getsigdefault (3),
+.BR posix_spawnattr_getsigmask (3),
+.BR posix_spawnattr_init (3),
+.BR posix_spawnattr_setflags (3),
+.BR posix_spawnattr_setpgroup (3),
+.BR posix_spawnattr_setschedparam (3),
+.BR posix_spawnattr_setschedpolicy (3),
+.BR posix_spawnattr_setsigdefault (3),
+.BR posix_spawnattr_setsigmask (3),
+.BR pthread_atfork (3),
+.IR <spawn.h> ,
+Base Definitions volume of POSIX.1-2001,
+.I http://www.opengroup.org/unix/online.html
diff --git a/man/man3/posix_spawnp.3 b/man/man3/posix_spawnp.3
new file mode 100644
index 000000000..a6f49d0ef
--- /dev/null
+++ b/man/man3/posix_spawnp.3
@@ -0,0 +1 @@
+.so man3/posix_spawn.3
diff --git a/man/man3/pow.3 b/man/man3/pow.3
new file mode 100644
index 000000000..6735d35ba
--- /dev/null
+++ b/man/man3/pow.3
@@ -0,0 +1,383 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-08-14 by Arnt Gulbrandsen <agulbra@troll.no>
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.TH pow 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pow, powf, powl \- power functions
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double pow(double " x ", double " y );
+.BI "float powf(float " x ", float " y );
+.BI "long double powl(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR powf (),
+.BR powl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the value of
+.I x
+raised to the
+power of
+.IR y .
+.SH RETURN VALUE
+On success, these functions return the value of
+.I x
+to the power of
+.IR y .
+.P
+If the result overflows,
+a range error occurs,
+.\" The range error is generated at least as far back as glibc 2.4
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the mathematically correct sign.
+.P
+If result underflows, and is not representable,
+a range error occurs,
+and 0.0 with the appropriate sign is returned.
+.\" POSIX.1 does not specify the sign of the zero,
+.\" but https://www.sourceware.org/bugzilla/show_bug.cgi?id=2678
+.\" points out that the zero has the wrong sign in some cases.
+.P
+.\" pow(\(+-0, <0 [[odd]]) = HUGE_VAL*
+If
+.I x
+is +0 or \-0,
+and
+.I y
+is an odd integer less than 0,
+a pole error occurs and
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+is returned,
+with the same sign as
+.IR x .
+.P
+.\" pow(\(+-0, <0 [[!odd]]) = HUGE_VAL*
+If
+.I x
+is +0 or \-0,
+and
+.I y
+is less than 0 and not an odd integer,
+a pole error occurs and
+.\" The pole error is generated at least as far back as glibc 2.4
+.RB + HUGE_VAL ,
+.RB + HUGE_VALF ,
+or
+.RB + HUGE_VALL ,
+is returned.
+.P
+.\" pow(\(+-0, >0 [[odd]]) = \(+-0
+If
+.I x
+is +0 (\-0),
+and
+.I y
+is an odd integer greater than 0,
+the result is +0 (\-0).
+.P
+.\" pow(\(+-0, >0 [[!odd]]) = +0
+If
+.I x
+is 0,
+and
+.I y
+greater than 0 and not an odd integer,
+the result is +0.
+.P
+.\" pow(-1, \(+-INFINITY) = 1.0
+If
+.I x
+is \-1,
+and
+.I y
+is positive infinity or negative infinity,
+the result is 1.0.
+.P
+.\" pow(+1, y) = 1.0
+If
+.I x
+is +1, the result is 1.0 (even if
+.I y
+is a NaN).
+.P
+.\" pow(x, \(+-0) = 1.0
+If
+.I y
+is 0, the result is 1.0 (even if
+.I x
+is a NaN).
+.P
+.\" pow(<0, y) = NaN
+If
+.I x
+is a finite value less than 0, and
+.I y
+is a finite noninteger, a domain error occurs,
+.\" The domain error is generated at least as far back as glibc 2.4
+and a NaN is returned.
+.P
+.\" pow(|x|<1, -INFINITY) = INFINITY
+If the absolute value of
+.I x
+is less than 1,
+and
+.I y
+is negative infinity,
+the result is positive infinity.
+.P
+.\" pow(|x|>1, -INFINITY) = +0
+If the absolute value of
+.I x
+is greater than 1,
+and
+.I y
+is negative infinity,
+the result is +0.
+.P
+.\" pow(|x|<1, INFINITY) = +0
+If the absolute value of
+.I x
+is less than 1,
+and
+.I y
+is positive infinity,
+the result is +0.
+.P
+.\" pow(|x|>1, INFINITY) = INFINITY
+If the absolute value of
+.I x
+is greater than 1,
+and
+.I y
+is positive infinity,
+the result is positive infinity.
+.P
+.\" pow(-INFINITY, <0 [[odd]]) = -0
+If
+.I x
+is negative infinity,
+and
+.I y
+is an odd integer less than 0,
+the result is \-0.
+.P
+.\" pow(-INFINITY, <0 [[!odd]]) = +0
+If
+.I x
+is negative infinity,
+and
+.I y
+less than 0 and not an odd integer,
+the result is +0.
+.P
+.\" pow(-INFINITY, >0 [[odd]]) = -INFINITY
+If
+.I x
+is negative infinity,
+and
+.I y
+is an odd integer greater than 0,
+the result is negative infinity.
+.P
+.\" pow(-INFINITY, >0 [[!odd]]) = INFINITY
+If
+.I x
+is negative infinity,
+and
+.I y
+greater than 0 and not an odd integer,
+the result is positive infinity.
+.P
+.\" pow(INFINITY, <0) = +0
+If
+.I x
+is positive infinity,
+and
+.I y
+less than 0,
+the result is +0.
+.P
+.\" pow(INFINITY, >0) = INFINITY
+If
+.I x
+is positive infinity,
+and
+.I y
+greater than 0,
+the result is positive infinity.
+.P
+.\" pow(NaN, y) or pow(x, NaN) = NaN
+Except as specified above, if
+.I x
+or
+.I y
+is a NaN, the result is a NaN.
+.SH ERRORS
+.\" FIXME . review status of this error
+.\" longstanding bug report for glibc:
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=369
+.\" For negative x, and -large and +large y, glibc 2.8 gives incorrect
+.\" results
+.\" pow(-0.5,-DBL_MAX)=nan
+.\" EDOM FE_INVALID nan; fail-errno fail-except fail-result;
+.\" FAIL (expected: range-error-overflow (ERANGE, FE_OVERFLOW); +INF)
+.\"
+.\" pow(-1.5,-DBL_MAX)=nan
+.\" EDOM FE_INVALID nan; fail-errno fail-except fail-result;
+.\" FAIL (expected: range-error-underflow (ERANGE, FE_UNDERFLOW); +0)
+.\"
+.\" pow(-0.5,DBL_MAX)=nan
+.\" EDOM FE_INVALID nan; fail-errno fail-except fail-result;
+.\" FAIL (expected: range-error-underflow (ERANGE, FE_UNDERFLOW); +0)
+.\"
+.\" pow(-1.5,DBL_MAX)=nan
+.\" EDOM FE_INVALID nan; fail-errno fail-except fail-result;
+.\" FAIL (expected: range-error-overflow (ERANGE, FE_OVERFLOW); +INF)
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is negative, and \fIy\fP is a finite noninteger
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Pole error: \fIx\fP is zero, and \fIy\fP is negative
+.I errno
+is set to
+.B ERANGE
+(but see BUGS).
+A divide-by-zero floating-point exception
+.RB ( FE_DIVBYZERO )
+is raised.
+.TP
+Range error: the result overflows
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error: the result underflows
+.I errno
+is set to
+.BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pow (),
+.BR powf (),
+.BR powl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH BUGS
+.SS Historical bugs (now fixed)
+Before glibc 2.28,
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=13932
+on some architectures (e.g., x86-64)
+.BR pow ()
+may be more than 10,000 times slower for some inputs
+than for other nearby inputs.
+This affects only
+.BR pow (),
+and not
+.BR powf ()
+nor
+.BR powl ().
+This problem was fixed
+.\" commit c3d466cba1692708a19c6ff829d0386c83a0c6e5
+in glibc 2.28.
+.P
+A number of bugs
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=3866
+in the glibc implementation of
+.BR pow ()
+were fixed in glibc 2.16.
+.P
+In glibc 2.9 and earlier,
+.\"
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6776
+when a pole error occurs,
+.I errno
+is set to
+.B EDOM
+instead of the POSIX-mandated
+.BR ERANGE .
+Since glibc 2.10,
+.\" or possibly 2.9, I haven't found the source code change
+.\" and I don't have a 2.9 system to test
+glibc does the right thing.
+.P
+In glibc 2.3.2 and earlier,
+.\" Actually, glibc 2.3.2 is the earliest test result I have; so yet
+.\" to confirm if this error occurs only in glibc 2.3.2.
+when an overflow or underflow error occurs, glibc's
+.BR pow ()
+generates a bogus invalid floating-point exception
+.RB ( FE_INVALID )
+in addition to the overflow or underflow exception.
+.SH SEE ALSO
+.BR cbrt (3),
+.BR cpow (3),
+.BR sqrt (3)
diff --git a/man/man3/pow10.3 b/man/man3/pow10.3
new file mode 100644
index 000000000..70fcaec1f
--- /dev/null
+++ b/man/man3/pow10.3
@@ -0,0 +1,56 @@
+'\" t
+.\" Copyright 2004 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pow10 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pow10, pow10f, pow10l \- base-10 power functions
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <math.h>
+.P
+.BI "double pow10(double " x );
+.BI "float pow10f(float " x );
+.BI "long double pow10l(long double " x );
+.fi
+.SH DESCRIPTION
+These functions return the value of 10 raised to the power
+.IR x .
+.P
+.BR "Note well" :
+These functions perform exactly the same task as the functions described in
+.BR exp10 (3),
+with the difference that the latter functions are now standardized
+in TS\ 18661-4:2015.
+Those latter functions should be used in preference
+to the functions described in this page.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pow10 (),
+.BR pow10f (),
+.BR pow10l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH VERSIONS
+glibc 2.1.
+Removed in glibc 2.27.
+.\" glibc commit 5a80d39d0d2587e9bd8e72f19e92eeb2a66fbe9e
+.SH SEE ALSO
+.BR exp10 (3),
+.BR pow (3)
diff --git a/man/man3/pow10f.3 b/man/man3/pow10f.3
new file mode 100644
index 000000000..8a7158015
--- /dev/null
+++ b/man/man3/pow10f.3
@@ -0,0 +1 @@
+.so man3/pow10.3
diff --git a/man/man3/pow10l.3 b/man/man3/pow10l.3
new file mode 100644
index 000000000..8a7158015
--- /dev/null
+++ b/man/man3/pow10l.3
@@ -0,0 +1 @@
+.so man3/pow10.3
diff --git a/man/man3/powerof2.3 b/man/man3/powerof2.3
new file mode 100644
index 000000000..f1b438f41
--- /dev/null
+++ b/man/man3/powerof2.3
@@ -0,0 +1,46 @@
+.\" Copyright (C) 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH powerof2 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+powerof2 \- test if a value is a power of 2
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/param.h>
+.P
+.BI "int powerof2(" x );
+.fi
+.SH DESCRIPTION
+This macro returns true if
+.I x
+is a power of 2,
+and false otherwise.
+.P
+.B 0
+is considered a power of 2.
+This can make sense considering wrapping of unsigned integers,
+and has interesting properties.
+.SH RETURN VALUE
+True or false,
+if
+.I x
+is a power of 2 or not,
+respectively.
+.SH STANDARDS
+BSD.
+.SH CAVEATS
+The arguments may be evaluated more than once.
+.P
+Because this macro is implemented using bitwise operations,
+some negative values can invoke undefined behavior.
+For example,
+the following invokes undefined behavior:
+.IR "powerof2(INT_MIN);".
+Call it only with unsigned types to be safe.
+.SH SEE ALSO
+.BR stdc_bit_ceil (3),
+.BR stdc_bit_floor (3)
diff --git a/man/man3/powf.3 b/man/man3/powf.3
new file mode 100644
index 000000000..63da756f5
--- /dev/null
+++ b/man/man3/powf.3
@@ -0,0 +1 @@
+.so man3/pow.3
diff --git a/man/man3/powl.3 b/man/man3/powl.3
new file mode 100644
index 000000000..63da756f5
--- /dev/null
+++ b/man/man3/powl.3
@@ -0,0 +1 @@
+.so man3/pow.3
diff --git a/man/man3/printf.3 b/man/man3/printf.3
new file mode 100644
index 000000000..15ed75439
--- /dev/null
+++ b/man/man3/printf.3
@@ -0,0 +1,1239 @@
+'\" t
+.\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" Earlier versions of this page influenced the present text.
+.\" It was derived from a Berkeley page with version
+.\"       @(#)printf.3    6.14 (Berkeley) 7/30/91
+.\" converted for Linux by faith@cs.unc.edu, updated by
+.\" Helmut.Geyer@iwr.uni-heidelberg.de, agulbra@troll.no and Bruno Haible.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1999-11-25 aeb - Rewritten, using SUSv2 and C99.
+.\" 2000-07-26 jsm28@hermes.cam.ac.uk - three small fixes
+.\" 2000-10-16 jsm28@hermes.cam.ac.uk - more fixes
+.\"
+.TH printf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+printf, fprintf, dprintf, sprintf, snprintf, vprintf, vfprintf, vdprintf,
+vsprintf, vsnprintf \- formatted output conversion
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int printf(const char *restrict " format ", ...);"
+.BI "int fprintf(FILE *restrict " stream ,
+.BI "            const char *restrict " format ", ...);"
+.BI "int dprintf(int " fd ,
+.BI "            const char *restrict " format ", ...);"
+.BI "int sprintf(char *restrict " str ,
+.BI "            const char *restrict " format ", ...);"
+.BI "int snprintf(char " str "[restrict ." size "], size_t " size ,
+.BI "            const char *restrict " format ", ...);"
+.P
+.BI "int vprintf(const char *restrict " format ", va_list " ap );
+.BI "int vfprintf(FILE *restrict " stream ,
+.BI "            const char *restrict " format ", va_list " ap );
+.BI "int vdprintf(int " fd ,
+.BI "            const char *restrict " format ", va_list " ap );
+.BI "int vsprintf(char *restrict " str ,
+.BI "            const char *restrict " format ", va_list " ap );
+.BI "int vsnprintf(char " str "[restrict ." size "], size_t " size ,
+.BI "            const char *restrict " format ", va_list " ap );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR snprintf (),
+.BR vsnprintf ():
+.nf
+    _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.P
+.BR dprintf (),
+.BR vdprintf ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The functions in the
+.BR printf ()
+family produce output according to a
+.I format
+as described below.
+The functions
+.BR printf ()
+and
+.BR vprintf ()
+write output to
+.IR stdout ,
+the standard output stream;
+.BR fprintf ()
+and
+.BR vfprintf ()
+write output to the given output
+.IR stream ;
+.BR sprintf (),
+.BR snprintf (),
+.BR vsprintf (),
+and
+.BR vsnprintf ()
+write to the character string
+.IR str .
+.P
+The function
+.BR dprintf ()
+is the same as
+.BR fprintf ()
+except that it outputs to a file descriptor,
+.IR fd ,
+instead of to a
+.BR stdio (3)
+stream.
+.P
+The functions
+.BR snprintf ()
+and
+.BR vsnprintf ()
+write at most
+.I size
+bytes (including the terminating null byte (\[aq]\e0\[aq])) to
+.IR str .
+.P
+The functions
+.BR vprintf (),
+.BR vfprintf (),
+.BR vdprintf (),
+.BR vsprintf (),
+.BR vsnprintf ()
+are equivalent to the functions
+.BR printf (),
+.BR fprintf (),
+.BR dprintf (),
+.BR sprintf (),
+.BR snprintf (),
+respectively, except that they are called with a
+.I va_list
+instead of a variable number of arguments.
+These functions do not call the
+.I va_end
+macro.
+Because they invoke the
+.I va_arg
+macro, the value of
+.I ap
+is undefined after the call.
+See
+.BR stdarg (3).
+.P
+All of these functions write the output under the control of a
+.I format
+string that specifies how subsequent arguments (or arguments accessed via
+the variable-length argument facilities of
+.BR stdarg (3))
+are converted for output.
+.P
+C99 and POSIX.1-2001 specify that the results are undefined if a call to
+.BR sprintf (),
+.BR snprintf (),
+.BR vsprintf (),
+or
+.BR vsnprintf ()
+would cause copying to take place between objects that overlap
+(e.g., if the target string array and one of the supplied input arguments
+refer to the same buffer).
+See CAVEATS.
+.SS Format of the format string
+The format string is a character string, beginning and ending
+in its initial shift state, if any.
+The format string is composed of zero or more directives: ordinary
+characters (not
+.BR % ),
+which are copied unchanged to the output stream;
+and conversion specifications, each of which results in fetching zero or
+more subsequent arguments.
+Each conversion specification is introduced by
+the character
+.BR % ,
+and ends with a
+.IR "conversion specifier" .
+In between there may be (in this order) zero or more
+.IR flags ,
+an optional minimum
+.IR "field width" ,
+an optional
+.I precision
+and an optional
+.IR "length modifier" .
+.P
+The overall syntax of a conversion specification is:
+.P
+.in +4n
+.nf
+%[$][flags][width][.precision][length modifier]conversion
+.fi
+.in
+.P
+The arguments must correspond properly (after type promotion) with the
+conversion specifier.
+By default, the arguments are used in the order
+given, where each \[aq]*\[aq] (see
+.I "Field width"
+and
+.I Precision
+below) and each conversion specifier asks for the next
+argument (and it is an error if insufficiently many arguments are given).
+One can also specify explicitly which argument is taken,
+at each place where an argument is required, by writing "%m$" instead
+of \[aq]%\[aq] and "*m$" instead of \[aq]*\[aq],
+where the decimal integer \fIm\fP denotes
+the position in the argument list of the desired argument, indexed starting
+from 1.
+Thus,
+.P
+.in +4n
+.EX
+printf("%*d", width, num);
+.EE
+.in
+.P
+and
+.P
+.in +4n
+.EX
+printf("%2$*1$d", width, num);
+.EE
+.in
+.P
+are equivalent.
+The second style allows repeated references to the
+same argument.
+The C99 standard does not include the style using \[aq]$\[aq],
+which comes from the Single UNIX Specification.
+If the style using
+\[aq]$\[aq] is used, it must be used throughout for all conversions taking an
+argument and all width and precision arguments, but it may be mixed
+with "%%" formats, which do not consume an argument.
+There may be no
+gaps in the numbers of arguments specified using \[aq]$\[aq]; for example, if
+arguments 1 and 3 are specified, argument 2 must also be specified
+somewhere in the format string.
+.P
+For some numeric conversions a radix character ("decimal point") or
+thousands' grouping character is used.
+The actual character used
+depends on the
+.B LC_NUMERIC
+part of the locale.
+(See
+.BR setlocale (3).)
+The POSIX locale
+uses \[aq].\[aq] as radix character, and does not have a grouping character.
+Thus,
+.P
+.in +4n
+.EX
+printf("%\[aq].2f", 1234567.89);
+.EE
+.in
+.P
+results in "1234567.89" in the POSIX locale, in "1234567,89" in the
+nl_NL locale, and in "1.234.567,89" in the da_DK locale.
+.SS Flag characters
+The character % is followed by zero or more of the following flags:
+.TP
+.B #
+The value should be converted to an "alternate form".
+For
+.B o
+conversions, the first character of the output string is made zero
+(by prefixing a 0 if it was not zero already).
+For
+.B x
+and
+.B X
+conversions, a nonzero result has the string "0x" (or "0X" for
+.B X
+conversions) prepended to it.
+For
+.BR a ,
+.BR A ,
+.BR e ,
+.BR E ,
+.BR f ,
+.BR F ,
+.BR g ,
+and
+.B G
+conversions, the result will always contain a decimal point, even if no
+digits follow it (normally, a decimal point appears in the results of those
+conversions only if a digit follows).
+For
+.B g
+and
+.B G
+conversions, trailing zeros are not removed from the result as they would
+otherwise be.
+For
+.BR m ,
+if
+.I errno
+contains a valid error code,
+the output of
+.I strerrorname_np(errno)
+is printed;
+otherwise, the value stored in
+.I errno
+is printed as a decimal number.
+For other conversions, the result is undefined.
+.TP
+.B \&0
+The value should be zero padded.
+For
+.BR d ,
+.BR i ,
+.BR o ,
+.BR u ,
+.BR x ,
+.BR X ,
+.BR a ,
+.BR A ,
+.BR e ,
+.BR E ,
+.BR f ,
+.BR F ,
+.BR g ,
+and
+.B G
+conversions, the converted value is padded on the left with zeros rather
+than blanks.
+If the
+.B \&0
+and
+.B \-
+flags both appear, the
+.B \&0
+flag is ignored.
+If a precision is given with an integer conversion
+.RB ( d ,
+.BR i ,
+.BR o ,
+.BR u ,
+.BR x ,
+and
+.BR X ),
+the
+.B \&0
+flag is ignored.
+For other conversions, the behavior is undefined.
+.TP
+.B \-
+The converted value is to be left adjusted on the field boundary.
+(The default is right justification.)
+The converted value is padded on the right with blanks, rather
+than on the left with blanks or zeros.
+A
+.B \-
+overrides a
+.B \&0
+if both are given.
+.TP
+.B \[aq] \[aq]
+(a space) A blank should be left before a positive number
+(or empty string) produced by a signed conversion.
+.TP
+.B +
+A sign (+ or \-) should always be placed before a number produced by a signed
+conversion.
+By default, a sign is used only for negative numbers.
+A
+.B +
+overrides a space if both are used.
+.P
+The five flag characters above are defined in the C99 standard.
+The Single UNIX Specification specifies one further flag character.
+.TP
+.B \[aq]
+For decimal conversion
+.RB ( i ,
+.BR d ,
+.BR u ,
+.BR f ,
+.BR F ,
+.BR g ,
+.BR G )
+the output is to be grouped with thousands' grouping characters
+if the locale information indicates any.
+(See
+.BR setlocale (3).)
+Note that many versions of
+.BR gcc (1)
+cannot parse this option and will issue a warning.
+(SUSv2 did not
+include \fI%\[aq]F\fP, but SUSv3 added it.)
+Note also that the default locale of a C program is "C"
+whose locale information indicates no thousands' grouping character.
+Therefore, without a prior call to
+.BR setlocale (3),
+no thousands' grouping characters will be printed.
+.P
+glibc 2.2 adds one further flag character.
+.TP
+.B I
+For decimal integer conversion
+.RB ( i ,
+.BR d ,
+.BR u )
+the output uses the locale's alternative output digits, if any.
+For example, since glibc 2.2.3 this will give Arabic-Indic digits
+in the Persian ("fa_IR") locale.
+.\" outdigits keyword in locale file
+.SS Field width
+An optional decimal digit string (with nonzero first digit) specifying
+a minimum field width.
+If the converted value has fewer characters
+than the field width, it will be padded with spaces on the left
+(or right, if the left-adjustment flag has been given).
+Instead of a decimal digit string one may write "*" or "*m$"
+(for some decimal integer \fIm\fP) to specify that the field width
+is given in the next argument, or in the \fIm\fP-th argument, respectively,
+which must be of type
+.IR int .
+A negative field width is taken as a \[aq]\-\[aq] flag followed by a
+positive field width.
+In no case does a nonexistent or small field width cause truncation of a
+field; if the result of a conversion is wider than the field width, the
+field is expanded to contain the conversion result.
+.SS Precision
+An optional precision, in the form of a period (\[aq].\[aq])  followed by an
+optional decimal digit string.
+Instead of a decimal digit string one may write "*" or "*m$"
+(for some decimal integer \fIm\fP) to specify that the precision
+is given in the next argument, or in the \fIm\fP-th argument, respectively,
+which must be of type
+.IR int .
+If the precision is given as just \[aq].\[aq], the precision is taken to
+be zero.
+A negative precision is taken as if the precision were omitted.
+This gives the minimum number of digits to appear for
+.BR d ,
+.BR i ,
+.BR o ,
+.BR u ,
+.BR x ,
+and
+.B X
+conversions, the number of digits to appear after the radix character for
+.BR a ,
+.BR A ,
+.BR e ,
+.BR E ,
+.BR f ,
+and
+.B F
+conversions, the maximum number of significant digits for
+.B g
+and
+.B G
+conversions, or the maximum number of characters to be printed from a
+string for
+.B s
+and
+.B S
+conversions.
+.SS Length modifier
+Here, "integer conversion" stands for
+.BR d ,
+.BR i ,
+.BR o ,
+.BR u ,
+.BR x ,
+or
+.B X
+conversion.
+.TP
+.B hh
+A following integer conversion corresponds to a
+.I signed char
+or
+.I unsigned char
+argument, or a following
+.B n
+conversion corresponds to a pointer to a
+.I signed char
+argument.
+.TP
+.B h
+A following integer conversion corresponds to a
+.I short
+or
+.I unsigned short
+argument, or a following
+.B n
+conversion corresponds to a pointer to a
+.I short
+argument.
+.TP
+.B l
+(ell) A following integer conversion corresponds to a
+.I long
+or
+.I unsigned long
+argument, or a following
+.B n
+conversion corresponds to a pointer to a
+.I long
+argument, or a following
+.B c
+conversion corresponds to a
+.I wint_t
+argument, or a following
+.B s
+conversion corresponds to a pointer to
+.I wchar_t
+argument.
+On a following
+.BR a ,
+.BR A ,
+.BR e ,
+.BR E ,
+.BR f ,
+.BR F ,
+.BR g ,
+or
+.B G
+conversion, this length modifier is ignored (C99; not in SUSv2).
+.TP
+.B ll
+(ell-ell).
+A following integer conversion corresponds to a
+.I long long
+or
+.I unsigned long long
+argument, or a following
+.B n
+conversion corresponds to a pointer to a
+.I long long
+argument.
+.TP
+.B q
+A synonym for
+.BR ll .
+This is a nonstandard extension, derived from BSD;
+avoid its use in new code.
+.TP
+.B L
+A following
+.BR a ,
+.BR A ,
+.BR e ,
+.BR E ,
+.BR f ,
+.BR F ,
+.BR g ,
+or
+.B G
+conversion corresponds to a
+.I long double
+argument.
+(C99 allows %LF, but SUSv2 does not.)
+.TP
+.B j
+A following integer conversion corresponds to an
+.I intmax_t
+or
+.I uintmax_t
+argument, or a following
+.B n
+conversion corresponds to a pointer to an
+.I intmax_t
+argument.
+.TP
+.B z
+A following integer conversion corresponds to a
+.I size_t
+or
+.I ssize_t
+argument, or a following
+.B n
+conversion corresponds to a pointer to a
+.I size_t
+argument.
+.TP
+.B Z
+A nonstandard synonym for
+.B z
+that predates the appearance of
+.BR z .
+Do not use in new code.
+.TP
+.B t
+A following integer conversion corresponds to a
+.I ptrdiff_t
+argument, or a following
+.B n
+conversion corresponds to a pointer to a
+.I ptrdiff_t
+argument.
+.P
+SUSv3 specifies all of the above,
+except for those modifiers explicitly noted as being nonstandard extensions.
+SUSv2 specified only the length modifiers
+.B h
+(in
+.BR hd ,
+.BR hi ,
+.BR ho ,
+.BR hx ,
+.BR hX ,
+.BR hn )
+and
+.B l
+(in
+.BR ld ,
+.BR li ,
+.BR lo ,
+.BR lx ,
+.BR lX ,
+.BR ln ,
+.BR lc ,
+.BR ls )
+and
+.B L
+(in
+.BR Le ,
+.BR LE ,
+.BR Lf ,
+.BR Lg ,
+.BR LG ).
+.P
+As a nonstandard extension, the GNU implementations treats
+.B ll
+and
+.B L
+as synonyms, so that one can, for example, write
+.B llg
+(as a synonym for the standards-compliant
+.BR Lg )
+and
+.B Ld
+(as a synonym for the standards compliant
+.BR lld ).
+Such usage is nonportable.
+.\"
+.SS Conversion specifiers
+A character that specifies the type of conversion to be applied.
+The conversion specifiers and their meanings are:
+.TP
+.BR d ", " i
+The
+.I int
+argument is converted to signed decimal notation.
+The precision, if any, gives the minimum number of digits
+that must appear; if the converted value requires fewer digits, it is
+padded on the left with zeros.
+The default precision is 1.
+When 0 is printed with an explicit precision 0, the output is empty.
+.TP
+.BR o ", " u ", " x ", " X
+The
+.I "unsigned int"
+argument is converted to unsigned octal
+.RB ( o ),
+unsigned decimal
+.RB ( u ),
+or unsigned hexadecimal
+.RB ( x
+and
+.BR X )
+notation.
+The letters
+.B abcdef
+are used for
+.B x
+conversions; the letters
+.B ABCDEF
+are used for
+.B X
+conversions.
+The precision, if any, gives the minimum number of digits
+that must appear; if the converted value requires fewer digits, it is
+padded on the left with zeros.
+The default precision is 1.
+When 0 is printed with an explicit precision 0, the output is empty.
+.TP
+.BR e ", " E
+The
+.I double
+argument is rounded and converted in the style
+.RB [\-]d \&. ddd e \(+-dd
+where there is one digit (which is nonzero if the argument is nonzero)
+before the decimal-point character and the number
+of digits after it is equal to the precision; if the precision is missing,
+it is taken as 6; if the precision is zero, no decimal-point character
+appears.
+An
+.B E
+conversion uses the letter
+.B E
+(rather than
+.BR e )
+to introduce the exponent.
+The exponent always contains at least two
+digits; if the value is zero, the exponent is 00.
+.TP
+.BR f ", " F
+The
+.I double
+argument is rounded and converted to decimal notation in the style
+.RB [\-]ddd \&. ddd,
+where the number of digits after the decimal-point character is equal to
+the precision specification.
+If the precision is missing, it is taken as
+6; if the precision is explicitly zero, no decimal-point character appears.
+If a decimal point appears, at least one digit appears before it.
+.IP
+(SUSv2 does not know about
+.B F
+and says that character string representations for infinity and NaN
+may be made available.
+SUSv3 adds a specification for
+.BR F .
+The C99 standard specifies "[\-]inf" or "[\-]infinity"
+for infinity, and a string starting with "nan" for NaN, in the case of
+.B f
+conversion, and "[\-]INF" or "[\-]INFINITY" or "NAN" in the case of
+.B F
+conversion.)
+.TP
+.BR g ", " G
+The
+.I double
+argument is converted in style
+.B f
+or
+.B e
+(or
+.B F
+or
+.B E
+for
+.B G
+conversions).
+The precision specifies the number of significant digits.
+If the precision is missing, 6 digits are given; if the precision is zero,
+it is treated as 1.
+Style
+.B e
+is used if the exponent from its conversion is less than \-4 or greater
+than or equal to the precision.
+Trailing zeros are removed from the
+fractional part of the result; a decimal point appears only if it is
+followed by at least one digit.
+.TP
+.BR a ", " A
+(C99; not in SUSv2, but added in SUSv3)
+For
+.B a
+conversion, the
+.I double
+argument is converted to hexadecimal notation (using the letters abcdef)
+in the style
+.RB [\-] 0x h \&. hhhh p \(+-d;
+for
+.B A
+conversion the prefix
+.BR 0X ,
+the letters ABCDEF, and the exponent separator
+.B P
+is used.
+There is one hexadecimal digit before the decimal point,
+and the number of digits after it is equal to the precision.
+The default precision suffices for an exact representation of the value
+if an exact representation in base 2 exists
+and otherwise is sufficiently large to distinguish values of type
+.IR double .
+The digit before the decimal point is unspecified for nonnormalized
+numbers, and nonzero but otherwise unspecified for normalized numbers.
+The exponent always contains at least one
+digit; if the value is zero, the exponent is 0.
+.TP
+.B c
+If no
+.B l
+modifier is present, the
+.I int
+argument is converted to an
+.IR "unsigned char" ,
+and the resulting character is written.
+If an
+.B l
+modifier is present, the
+.I wint_t
+(wide character) argument is converted to a multibyte sequence by a call
+to the
+.BR wcrtomb (3)
+function, with a conversion state starting in the initial state, and the
+resulting multibyte string is written.
+.TP
+.B s
+If no
+.B l
+modifier is present: the
+.I "const char\ *"
+argument is expected to be a pointer to an array of character type (pointer
+to a string).
+Characters from the array are written up to (but not
+including) a terminating null byte (\[aq]\e0\[aq]);
+if a precision is specified, no more than the number specified
+are written.
+If a precision is given, no null byte need be present;
+if the precision is not specified, or is greater than the size of the
+array, the array must contain a terminating null byte.
+.IP
+If an
+.B l
+modifier is present: the
+.I "const wchar_t\ *"
+argument is expected to be a pointer to an array of wide characters.
+Wide characters from the array are converted to multibyte characters
+(each by a call to the
+.BR wcrtomb (3)
+function, with a conversion state starting in the initial state before
+the first wide character), up to and including a terminating null
+wide character.
+The resulting multibyte characters are written up to
+(but not including) the terminating null byte.
+If a precision is
+specified, no more bytes than the number specified are written, but
+no partial multibyte characters are written.
+Note that the precision
+determines the number of
+.I bytes
+written, not the number of
+.I wide characters
+or
+.IR "screen positions" .
+The array must contain a terminating null wide character, unless a
+precision is given and it is so small that the number of bytes written
+exceeds it before the end of the array is reached.
+.TP
+.B C
+(Not in C99 or C11, but in SUSv2, SUSv3, and SUSv4.)
+Synonym for
+.BR lc .
+Don't use.
+.TP
+.B S
+(Not in C99 or C11, but in SUSv2, SUSv3, and SUSv4.)
+Synonym for
+.BR ls .
+Don't use.
+.TP
+.B p
+The
+.I "void\ *"
+pointer argument is printed in hexadecimal (as if by
+.B %#x
+or
+.BR %#lx ).
+.TP
+.B n
+The number of characters written so far is stored into the integer
+pointed to by the corresponding argument.
+That argument shall be an
+.IR "int\ *" ,
+or variant whose size matches the (optionally)
+supplied integer length modifier.
+No argument is converted.
+(This specifier is not supported by the bionic C library.)
+The behavior is undefined if the conversion specification includes
+any flags, a field width, or a precision.
+.TP
+.B m
+(glibc extension; supported by uClibc and musl.)
+Print output of
+.I strerror(errno)
+(or
+.I strerrorname_np(errno)
+in the alternate form).
+No argument is required.
+.TP
+.B %
+A \[aq]%\[aq] is written.
+No argument is converted.
+The complete conversion
+specification is \[aq]%%\[aq].
+.SH RETURN VALUE
+Upon successful return, these functions return the number of bytes
+printed (excluding the null byte used to end output to strings).
+.P
+The functions
+.BR snprintf ()
+and
+.BR vsnprintf ()
+do not write more than
+.I size
+bytes (including the terminating null byte (\[aq]\e0\[aq])).
+If the output was truncated due to this limit, then the return value
+is the number of characters (excluding the terminating null byte)
+which would have been written to the final string if enough space
+had been available.
+Thus, a return value of
+.I size
+or more means that the output was truncated.
+(See also below under CAVEATS.)
+.P
+If an output error is encountered, a negative value is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR printf (),
+.BR fprintf (),
+.BR sprintf (),
+.BR snprintf (),
+.BR vprintf (),
+.BR vfprintf (),
+.BR vsprintf (),
+.BR vsnprintf ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+.TP
+.BR fprintf ()
+.TQ
+.BR printf ()
+.TQ
+.BR sprintf ()
+.TQ
+.BR vprintf ()
+.TQ
+.BR vfprintf ()
+.TQ
+.BR vsprintf ()
+.TQ
+.BR snprintf ()
+.TQ
+.BR vsnprintf ()
+C11, POSIX.1-2008.
+.TP
+.BR dprintf ()
+.TQ
+.BR vdprintf ()
+GNU, POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR fprintf ()
+.TQ
+.BR printf ()
+.TQ
+.BR sprintf ()
+.TQ
+.BR vprintf ()
+.TQ
+.BR vfprintf ()
+.TQ
+.BR vsprintf ()
+C89, POSIX.1-2001.
+.TP
+.BR snprintf ()
+.TQ
+.BR vsnprintf ()
+SUSv2, C99, POSIX.1-2001.
+.IP
+Concerning the return value of
+.BR snprintf (),
+SUSv2 and C99 contradict each other: when
+.BR snprintf ()
+is called with
+.IR size =0
+then SUSv2 stipulates an unspecified return value less than 1,
+while C99 allows
+.I str
+to be NULL in this case, and gives the return value (as always)
+as the number of characters that would have been written in case
+the output string has been large enough.
+POSIX.1-2001 and later align their specification of
+.BR snprintf ()
+with C99.
+.TP
+.BR dprintf ()
+.TQ
+.BR vdprintf ()
+GNU, POSIX.1-2008.
+.P
+.\" Linux libc4 knows about the five C standard flags.
+.\" It knows about the length modifiers \fBh\fP, \fBl\fP, \fBL\fP,
+.\" and the conversions
+.\" \fBc\fP, \fBd\fP, \fBe\fP, \fBE\fP, \fBf\fP, \fBF\fP,
+.\" \fBg\fP, \fBG\fP, \fBi\fP, \fBn\fP, \fBo\fP, \fBp\fP,
+.\" \fBs\fP, \fBu\fP, \fBx\fP, and \fBX\fP,
+.\" where \fBF\fP is a synonym for \fBf\fP.
+.\" Additionally, it accepts \fBD\fP, \fBO\fP, and \fBU\fP as synonyms
+.\" for \fBld\fP, \fBlo\fP, and \fBlu\fP.
+.\" (This is bad, and caused serious bugs later, when
+.\" support for \fB%D\fP disappeared.)
+.\" No locale-dependent radix character,
+.\" no thousands' separator, no NaN or infinity, no "%m$" and "*m$".
+.\" .P
+.\" Linux libc5 knows about the five C standard flags and the \[aq] flag,
+.\" locale, "%m$" and "*m$".
+.\" It knows about the length modifiers \fBh\fP, \fBl\fP, \fBL\fP,
+.\" \fBZ\fP, and \fBq\fP, but accepts \fBL\fP and \fBq\fP
+.\" both for \fIlong double\fP and for \fIlong long\fP (this is a bug).
+.\" It no longer recognizes \fBF\fP, \fBD\fP, \fBO\fP, and \fBU\fP,
+.\" but adds the conversion character
+.\" .BR m ,
+.\" which outputs
+.\" .IR strerror(errno) .
+.\" .P
+.\" glibc 2.0 adds conversion characters \fBC\fP and \fBS\fP.
+.\" .P
+glibc 2.1 adds length modifiers \fBhh\fP, \fBj\fP, \fBt\fP, and \fBz\fP
+and conversion characters \fBa\fP and \fBA\fP.
+.P
+glibc 2.2 adds the conversion character \fBF\fP with C99 semantics,
+and the flag character \fBI\fP.
+.P
+glibc 2.35 gives a meaning to the alternate form
+.RB ( # )
+of the
+.B m
+conversion specifier, that is
+.IR %#m .
+.SH CAVEATS
+Some programs imprudently rely on code such as the following
+.P
+.in +4n
+.EX
+sprintf(buf, "%s some further text", buf);
+.EE
+.in
+.P
+to append text to
+.IR buf .
+However, the standards explicitly note that the results are undefined
+if source and destination buffers overlap when calling
+.BR sprintf (),
+.BR snprintf (),
+.BR vsprintf (),
+and
+.BR vsnprintf ().
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=7075
+Depending on the version of
+.BR gcc (1)
+used, and the compiler options employed, calls such as the above will
+.B not
+produce the expected results.
+.P
+The glibc implementation of the functions
+.BR snprintf ()
+and
+.BR vsnprintf ()
+conforms to the C99 standard, that is, behaves as described above,
+since glibc 2.1.
+Until glibc 2.0.6, they would return \-1
+when the output was truncated.
+.\" .SH HISTORY
+.\" UNIX V7 defines the three routines
+.\" .BR printf (),
+.\" .BR fprintf (),
+.\" .BR sprintf (),
+.\" and has the flag \-, the width or precision *, the length modifier l,
+.\" and the conversions doxfegcsu, and also D,O,U,X as synonyms for ld,lo,lu,lx.
+.\" This is still true for 2.9.1BSD, but 2.10BSD has the flags
+.\" #, + and <space> and no longer mentions D,O,U,X.
+.\" 2.11BSD has
+.\" .BR vprintf (),
+.\" .BR vfprintf (),
+.\" .BR vsprintf (),
+.\" and warns not to use D,O,U,X.
+.\" 4.3BSD Reno has the flag 0, the length modifiers h and L,
+.\" and the conversions n, p, E, G, X (with current meaning)
+.\" and deprecates D,O,U.
+.\" 4.4BSD introduces the functions
+.\" .BR snprintf ()
+.\" and
+.\" .BR vsnprintf (),
+.\" and the length modifier q.
+.\" FreeBSD also has functions
+.\" .BR asprintf ()
+.\" and
+.\" .BR vasprintf (),
+.\" that allocate a buffer large enough for
+.\" .BR sprintf ().
+.\" In glibc there are functions
+.\" .BR dprintf ()
+.\" and
+.\" .BR vdprintf ()
+.\" that print to a file descriptor instead of a stream.
+.SH BUGS
+Because
+.BR sprintf ()
+and
+.BR vsprintf ()
+assume an arbitrarily long string, callers must be careful not to overflow
+the actual space; this is often impossible to assure.
+Note that the length
+of the strings produced is locale-dependent and difficult to predict.
+Use
+.BR snprintf ()
+and
+.BR vsnprintf ()
+instead (or
+.BR asprintf (3)
+and
+.BR vasprintf (3)).
+.\" .P
+.\" Linux libc4.[45] does not have a
+.\" .BR snprintf (),
+.\" but provides a libbsd that contains an
+.\" .BR snprintf ()
+.\" equivalent to
+.\" .BR sprintf (),
+.\" that is, one that ignores the
+.\" .I size
+.\" argument.
+.\" Thus, the use of
+.\" .BR snprintf ()
+.\" with early libc4 leads to serious security problems.
+.P
+Code such as
+.BI printf( foo );
+often indicates a bug, since
+.I foo
+may contain a % character.
+If
+.I foo
+comes from untrusted user input, it may contain \fB%n\fP, causing the
+.BR printf ()
+call to write to memory and creating a security hole.
+.\" .P
+.\" Some floating-point conversions under early libc4
+.\" caused memory leaks.
+.SH EXAMPLES
+To print
+.I Pi
+to five decimal places:
+.P
+.in +4n
+.EX
+#include <math.h>
+#include <stdio.h>
+fprintf(stdout, "pi = %.5f\en", 4 * atan(1.0));
+.EE
+.in
+.P
+To print a date and time in the form "Sunday, July 3, 10:02",
+where
+.I weekday
+and
+.I month
+are pointers to strings:
+.P
+.in +4n
+.EX
+#include <stdio.h>
+fprintf(stdout, "%s, %s %d, %.2d:%.2d\en",
+        weekday, month, day, hour, min);
+.EE
+.in
+.P
+Many countries use the day-month-year order.
+Hence, an internationalized version must be able to print
+the arguments in an order specified by the format:
+.P
+.in +4n
+.EX
+#include <stdio.h>
+fprintf(stdout, format,
+        weekday, month, day, hour, min);
+.EE
+.in
+.P
+where
+.I format
+depends on locale, and may permute the arguments.
+With the value:
+.P
+.in +4n
+.EX
+"%1$s, %3$d. %2$s, %4$d:%5$.2d\en"
+.EE
+.in
+.P
+one might obtain "Sonntag, 3. Juli, 10:02".
+.P
+To allocate a sufficiently large string and print into it
+(code correct for both glibc 2.0 and glibc 2.1):
+.P
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+\&
+char *
+make_message(const char *fmt, ...)
+{
+    int n = 0;
+    size_t size = 0;
+    char *p = NULL;
+    va_list ap;
+\&
+    /* Determine required size. */
+\&
+    va_start(ap, fmt);
+    n = vsnprintf(p, size, fmt, ap);
+    va_end(ap);
+\&
+    if (n < 0)
+        return NULL;
+\&
+    size = (size_t) n + 1;      /* One extra byte for \[aq]\e0\[aq] */
+    p = malloc(size);
+    if (p == NULL)
+        return NULL;
+\&
+    va_start(ap, fmt);
+    n = vsnprintf(p, size, fmt, ap);
+    va_end(ap);
+\&
+    if (n < 0) {
+        free(p);
+        return NULL;
+    }
+\&
+    return p;
+}
+.EE
+.P
+If truncation occurs in glibc versions prior to glibc 2.0.6,
+this is treated as an error instead of being handled gracefully.
+.SH SEE ALSO
+.BR printf (1),
+.BR asprintf (3),
+.BR puts (3),
+.BR scanf (3),
+.BR setlocale (3),
+.BR strfromd (3),
+.BR wcrtomb (3),
+.BR wprintf (3),
+.BR locale (5)
diff --git a/man/man3/profil.3 b/man/man3/profil.3
new file mode 100644
index 000000000..dd72c5ef2
--- /dev/null
+++ b/man/man3/profil.3
@@ -0,0 +1,94 @@
+'\" t
+.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Fri Jun 23 01:35:19 1995 Andries Brouwer <aeb@cwi.nl>
+.\" (prompted by Bas V. de Bakker <bas@phys.uva.nl>)
+.\" Corrected (and moved to man3), 980612, aeb
+.TH profil 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+profil \- execution time profile
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "int profil(unsigned short *" buf ", size_t " bufsiz ,
+.BI "           size_t " offset ", unsigned int " scale );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR profil ():
+.nf
+    Since glibc 2.21:
+.\"             commit 266865c0e7b79d4196e2cc393693463f03c90bd8
+        _DEFAULT_SOURCE
+    In glibc 2.19 and 2.20:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+This routine provides a means to find out in what areas your program
+spends most of its time.
+The argument
+.I buf
+points to
+.I bufsiz
+bytes of core.
+Every virtual 10 milliseconds, the user's program counter (PC)
+is examined:
+.I offset
+is subtracted and the result is multiplied by
+.I scale
+and divided by 65536.
+If the resulting value is less than
+.IR bufsiz ,
+then the corresponding entry in
+.I buf
+is incremented.
+If
+.I buf
+is NULL, profiling is disabled.
+.SH RETURN VALUE
+Zero is always returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR profil ()
+T}	Thread safety	MT-Unsafe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+Similar to a call in SVr4.
+.SH BUGS
+.BR profil ()
+cannot be used on a program that also uses
+.B ITIMER_PROF
+interval timers (see
+.BR setitimer (2)).
+.P
+True kernel profiling provides more accurate results.
+.\" Libc 4.4 contained a kernel patch providing a system call profil.
+.SH SEE ALSO
+.BR gprof (1),
+.BR sprof (1),
+.BR setitimer (2),
+.BR sigaction (2),
+.BR signal (2)
diff --git a/man/man3/program_invocation_name.3 b/man/man3/program_invocation_name.3
new file mode 100644
index 000000000..f4b442d8a
--- /dev/null
+++ b/man/man3/program_invocation_name.3
@@ -0,0 +1,66 @@
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Permission is hereby granted, free of charge, to any person obtaining
+.\" a copy of this software and associated documentation files (the
+.\" "Software"), to deal in the Software without restriction, including
+.\" without limitation the rights to use, copy, modify, merge, publish,
+.\" distribute, sublicense, and/or sell copies of the Software, and to
+.\" permit persons to whom the Software is furnished to do so, subject to
+.\" the following conditions:
+.\"
+.\" The above copyright notice and this permission notice shall be
+.\" included in all copies or substantial portions of the Software.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+.\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+.\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+.\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+.\" %%%LICENSE_END
+.\"
+.TH program_invocation_name 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+program_invocation_name, program_invocation_short_name \- \
+obtain name used to invoke calling program
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <errno.h>
+.P
+.BI "extern char *" program_invocation_name ;
+.BI "extern char *" program_invocation_short_name ;
+.fi
+.SH DESCRIPTION
+.I program_invocation_name
+contains the name that was used to invoke the calling program.
+This is the same as the value of
+.I argv[0]
+in
+.IR main (),
+with the difference that the scope of
+.I program_invocation_name
+is global.
+.P
+.I program_invocation_short_name
+contains the basename component of name that was used to invoke
+the calling program.
+That is, it is the same value as
+.IR program_invocation_name ,
+with all text up to and including the final slash (/), if any, removed.
+.P
+These variables are automatically initialized by the glibc run-time
+startup code.
+.SH VERSIONS
+The Linux-specific
+.IR /proc/ pid /cmdline
+file provides access to similar information.
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man3/program_invocation_short_name.3 b/man/man3/program_invocation_short_name.3
new file mode 100644
index 000000000..f603f6c7f
--- /dev/null
+++ b/man/man3/program_invocation_short_name.3
@@ -0,0 +1 @@
+.so man3/program_invocation_name.3
diff --git a/man/man3/psiginfo.3 b/man/man3/psiginfo.3
new file mode 100644
index 000000000..cd748fa57
--- /dev/null
+++ b/man/man3/psiginfo.3
@@ -0,0 +1 @@
+.so man3/psignal.3
diff --git a/man/man3/psignal.3 b/man/man3/psignal.3
new file mode 100644
index 000000000..583c532d3
--- /dev/null
+++ b/man/man3/psignal.3
@@ -0,0 +1,114 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:45:17 1993 by Rik Faith (faith@cs.unc.edu)
+.TH psignal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+psignal, psiginfo \- print signal description
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "void psignal(int " sig ", const char *" s );
+.BI "void psiginfo(const siginfo_t *" pinfo ", const char *" s );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR psignal ():
+.nf
+    Since glibc 2.19:
+            _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR psiginfo ():
+.nf
+    _POSIX_C_SOURCE >= 200809L
+.fi
+.SH DESCRIPTION
+The
+.BR psignal ()
+function displays a message on \fIstderr\fP
+consisting of the string \fIs\fP, a colon, a space, a string
+describing the signal number \fIsig\fP, and a trailing newline.
+If the string \fIs\fP is NULL or empty, the colon and space are omitted.
+If \fIsig\fP is invalid,
+the message displayed will indicate an unknown signal.
+.P
+The
+.BR psiginfo ()
+function is like
+.BR psignal (),
+except that it displays information about the signal described by
+.IR pinfo ,
+which should point to a valid
+.I siginfo_t
+structure.
+As well as the signal description,
+.BR psiginfo ()
+displays information about the origin of the signal,
+and other information relevant to the signal
+(e.g., the relevant memory address for hardware-generated signals,
+the child process ID for
+.BR SIGCHLD ,
+and the user ID and process ID of the sender, for signals set using
+.BR kill (2)
+or
+.BR sigqueue (3)).
+.SH RETURN VALUE
+The
+.BR psignal ()
+and
+.BR psiginfo ()
+functions return no value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR psignal (),
+.BR psiginfo ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.10.
+POSIX.1-2008, 4.3BSD.
+.SH BUGS
+Up to glibc 2.12,
+.BR psiginfo ()
+had the following bugs:
+.IP \[bu] 3
+In some circumstances, a trailing newline is not printed.
+.\" FIXME . http://sourceware.org/bugzilla/show_bug.cgi?id=12107
+.\" Reportedly now fixed; check glibc 2.13
+.IP \[bu]
+Additional details are not displayed for real-time signals.
+.\" FIXME . http://sourceware.org/bugzilla/show_bug.cgi?id=12108
+.\" Reportedly now fixed; check glibc 2.13
+.SH SEE ALSO
+.BR sigaction (2),
+.BR perror (3),
+.BR strsignal (3),
+.BR signal (7)
diff --git a/man/man3/pthread_atfork.3 b/man/man3/pthread_atfork.3
new file mode 100644
index 000000000..a1226cfa4
--- /dev/null
+++ b/man/man3/pthread_atfork.3
@@ -0,0 +1,108 @@
+.\" Copyright (C) 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_atfork 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_atfork \- register fork handlers
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B  #include <pthread.h>
+.P
+.BI "int pthread_atfork(void (*" prepare ")(void), void (*" parent ")(void),"
+.BI "                   void (*" child ")(void));"
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_atfork ()
+function registers fork handlers that are to be executed when
+.BR fork (2)
+is called by any thread in a process.
+The handlers are executed in the context of the thread that calls
+.BR fork (2).
+.P
+Three kinds of handler can be registered:
+.IP \[bu] 3
+.I prepare
+specifies a handler that is executed in the parent process before
+.BR fork (2)
+processing starts.
+.IP \[bu]
+.I parent
+specifies a handler that is executed in the parent process after
+.BR fork (2)
+processing completes.
+.IP \[bu]
+.I child
+specifies a handler that is executed in the child process after
+.BR fork (2)
+processing completes.
+.P
+Any of the three arguments may be NULL if no handler is needed
+in the corresponding phase of
+.BR fork (2)
+processing.
+.SH RETURN VALUE
+On success,
+.BR pthread_atfork ()
+returns zero.
+On error, it returns an error number.
+.BR pthread_atfork ()
+may be called multiple times by a process
+to register additional handlers.
+The handlers for each phase are called in a specified order: the
+.I prepare
+handlers are called in reverse order of registration; the
+.I parent
+and
+.I child
+handlers are called in the order of registration.
+.SH ERRORS
+.TP
+.B ENOMEM
+Could not allocate memory to record the fork handler list entry.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+When
+.BR fork (2)
+is called in a multithreaded process,
+only the calling thread is duplicated in the child process.
+The original intention of
+.BR pthread_atfork ()
+was to allow the child process to be returned to a consistent state.
+For example, at the time of the call to
+.BR fork (2),
+other threads may have locked mutexes that are visible in the
+user-space memory duplicated in the child.
+Such mutexes would never be unlocked,
+since the threads that placed the locks are not duplicated in the child.
+The intent of
+.BR pthread_atfork ()
+was to provide a mechanism whereby the application (or a library)
+could ensure that mutexes and other process and thread state would be
+restored to a consistent state.
+In practice, this task is generally too difficult to be practicable.
+.P
+After a
+.BR fork (2)
+in a multithreaded process returns in the child,
+the child should call only async-signal-safe functions (see
+.BR signal\-safety (7))
+until such time as it calls
+.BR execve (2)
+to execute a new program.
+.P
+POSIX.1 specifies that
+.BR pthread_atfork ()
+shall not fail with the error
+.BR EINTR .
+.SH SEE ALSO
+.BR fork (2),
+.BR atexit (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_destroy.3 b/man/man3/pthread_attr_destroy.3
new file mode 100644
index 000000000..4e7c9494d
--- /dev/null
+++ b/man/man3/pthread_attr_destroy.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_init.3
diff --git a/man/man3/pthread_attr_getaffinity_np.3 b/man/man3/pthread_attr_getaffinity_np.3
new file mode 100644
index 000000000..c6af8fa49
--- /dev/null
+++ b/man/man3/pthread_attr_getaffinity_np.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setaffinity_np.3
diff --git a/man/man3/pthread_attr_getdetachstate.3 b/man/man3/pthread_attr_getdetachstate.3
new file mode 100644
index 000000000..c57ecd59d
--- /dev/null
+++ b/man/man3/pthread_attr_getdetachstate.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setdetachstate.3
diff --git a/man/man3/pthread_attr_getguardsize.3 b/man/man3/pthread_attr_getguardsize.3
new file mode 100644
index 000000000..766ca2f19
--- /dev/null
+++ b/man/man3/pthread_attr_getguardsize.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setguardsize.3
diff --git a/man/man3/pthread_attr_getinheritsched.3 b/man/man3/pthread_attr_getinheritsched.3
new file mode 100644
index 000000000..65239cb76
--- /dev/null
+++ b/man/man3/pthread_attr_getinheritsched.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setinheritsched.3
diff --git a/man/man3/pthread_attr_getschedparam.3 b/man/man3/pthread_attr_getschedparam.3
new file mode 100644
index 000000000..3f830fdce
--- /dev/null
+++ b/man/man3/pthread_attr_getschedparam.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setschedparam.3
diff --git a/man/man3/pthread_attr_getschedpolicy.3 b/man/man3/pthread_attr_getschedpolicy.3
new file mode 100644
index 000000000..10f740c2c
--- /dev/null
+++ b/man/man3/pthread_attr_getschedpolicy.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setschedpolicy.3
diff --git a/man/man3/pthread_attr_getscope.3 b/man/man3/pthread_attr_getscope.3
new file mode 100644
index 000000000..965fd629a
--- /dev/null
+++ b/man/man3/pthread_attr_getscope.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setscope.3
diff --git a/man/man3/pthread_attr_getsigmask_np.3 b/man/man3/pthread_attr_getsigmask_np.3
new file mode 100644
index 000000000..92b55d302
--- /dev/null
+++ b/man/man3/pthread_attr_getsigmask_np.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setsigmask_np.3
diff --git a/man/man3/pthread_attr_getstack.3 b/man/man3/pthread_attr_getstack.3
new file mode 100644
index 000000000..2b20d7eda
--- /dev/null
+++ b/man/man3/pthread_attr_getstack.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setstack.3
diff --git a/man/man3/pthread_attr_getstackaddr.3 b/man/man3/pthread_attr_getstackaddr.3
new file mode 100644
index 000000000..49d8a85d4
--- /dev/null
+++ b/man/man3/pthread_attr_getstackaddr.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setstackaddr.3
diff --git a/man/man3/pthread_attr_getstacksize.3 b/man/man3/pthread_attr_getstacksize.3
new file mode 100644
index 000000000..52431f58f
--- /dev/null
+++ b/man/man3/pthread_attr_getstacksize.3
@@ -0,0 +1 @@
+.so man3/pthread_attr_setstacksize.3
diff --git a/man/man3/pthread_attr_init.3 b/man/man3/pthread_attr_init.3
new file mode 100644
index 000000000..dfd5ac67f
--- /dev/null
+++ b/man/man3/pthread_attr_init.3
@@ -0,0 +1,313 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_init 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_init, pthread_attr_destroy \- initialize and destroy
+thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_init(pthread_attr_t *" attr );
+.BI "int pthread_attr_destroy(pthread_attr_t *" attr );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_init ()
+function initializes the thread attributes object pointed to by
+.I attr
+with default attribute values.
+After this call, individual attributes of the object can be set
+using various related functions (listed under SEE ALSO),
+and then the object can be used in one or more
+.BR pthread_create (3)
+calls that create threads.
+.P
+Calling
+.BR pthread_attr_init ()
+on a thread attributes object that has already been initialized
+results in undefined behavior.
+.P
+When a thread attributes object is no longer required,
+it should be destroyed using the
+.BR pthread_attr_destroy ()
+function.
+Destroying a thread attributes object has no effect
+on threads that were created using that object.
+.P
+Once a thread attributes object has been destroyed,
+it can be reinitialized using
+.BR pthread_attr_init ().
+Any other use of a destroyed thread attributes object
+has undefined results.
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+POSIX.1 documents an
+.B ENOMEM
+error for
+.BR pthread_attr_init ();
+on Linux these functions always succeed
+(but portable and future-proof applications should nevertheless
+handle a possible error return).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_init (),
+.BR pthread_attr_destroy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The
+.I pthread_attr_t
+type should be treated as opaque:
+any access to the object other than via pthreads functions
+is nonportable and produces undefined results.
+.SH EXAMPLES
+The program below optionally makes use of
+.BR pthread_attr_init ()
+and various related functions to initialize a thread attributes
+object that is used to create a single thread.
+Once created, the thread uses the
+.BR pthread_getattr_np (3)
+function (a nonstandard GNU extension) to retrieve the thread's
+attributes, and then displays those attributes.
+.P
+If the program is run with no command-line argument,
+then it passes NULL as the
+.I attr
+argument of
+.BR pthread_create (3),
+so that the thread is created with default attributes.
+Running the program on Linux/x86-32 with the NPTL threading implementation,
+we see the following:
+.P
+.in +4n
+.EX
+.\" Results from glibc 2.8, SUSE 11.0; Oct 2008
+.RB "$" " ulimit \-s" "       # No stack limit ==> default stack size is 2 MB"
+unlimited
+.RB "$" " ./a.out"
+Thread attributes:
+        Detach state        = PTHREAD_CREATE_JOINABLE
+        Scope               = PTHREAD_SCOPE_SYSTEM
+        Inherit scheduler   = PTHREAD_INHERIT_SCHED
+        Scheduling policy   = SCHED_OTHER
+        Scheduling priority = 0
+        Guard size          = 4096 bytes
+        Stack address       = 0x40196000
+        Stack size          = 0x201000 bytes
+.EE
+.in
+.P
+When we supply a stack size as a command-line argument,
+the program initializes a thread attributes object,
+sets various attributes in that object,
+and passes a pointer to the object in the call to
+.BR pthread_create (3).
+Running the program on Linux/x86-32 with the NPTL threading implementation,
+we see the following:
+.P
+.in +4n
+.EX
+.\" Results from glibc 2.8, SUSE 11.0; Oct 2008
+.RB "$" " ./a.out 0x3000000"
+posix_memalign() allocated at 0x40197000
+Thread attributes:
+        Detach state        = PTHREAD_CREATE_DETACHED
+        Scope               = PTHREAD_SCOPE_SYSTEM
+        Inherit scheduler   = PTHREAD_EXPLICIT_SCHED
+        Scheduling policy   = SCHED_OTHER
+        Scheduling priority = 0
+        Guard size          = 0 bytes
+        Stack address       = 0x40197000
+        Stack size          = 0x3000000 bytes
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_attr_init.c)
+.EX
+#define _GNU_SOURCE     /* To get pthread_getattr_np() declaration */
+#include <err.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+static void
+display_pthread_attr(pthread_attr_t *attr, char *prefix)
+{
+    int s, i;
+    size_t v;
+    void *stkaddr;
+    struct sched_param sp;
+\&
+    s = pthread_attr_getdetachstate(attr, &i);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getdetachstate");
+    printf("%sDetach state        = %s\en", prefix,
+           (i == PTHREAD_CREATE_DETACHED) ? "PTHREAD_CREATE_DETACHED" :
+           (i == PTHREAD_CREATE_JOINABLE) ? "PTHREAD_CREATE_JOINABLE" :
+           "???");
+\&
+    s = pthread_attr_getscope(attr, &i);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getscope");
+    printf("%sScope               = %s\en", prefix,
+           (i == PTHREAD_SCOPE_SYSTEM)  ? "PTHREAD_SCOPE_SYSTEM" :
+           (i == PTHREAD_SCOPE_PROCESS) ? "PTHREAD_SCOPE_PROCESS" :
+           "???");
+\&
+    s = pthread_attr_getinheritsched(attr, &i);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getinheritsched");
+    printf("%sInherit scheduler   = %s\en", prefix,
+           (i == PTHREAD_INHERIT_SCHED)  ? "PTHREAD_INHERIT_SCHED" :
+           (i == PTHREAD_EXPLICIT_SCHED) ? "PTHREAD_EXPLICIT_SCHED" :
+           "???");
+\&
+    s = pthread_attr_getschedpolicy(attr, &i);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getschedpolicy");
+    printf("%sScheduling policy   = %s\en", prefix,
+           (i == SCHED_OTHER) ? "SCHED_OTHER" :
+           (i == SCHED_FIFO)  ? "SCHED_FIFO" :
+           (i == SCHED_RR)    ? "SCHED_RR" :
+           "???");
+\&
+    s = pthread_attr_getschedparam(attr, &sp);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getschedparam");
+    printf("%sScheduling priority = %d\en", prefix, sp.sched_priority);
+\&
+    s = pthread_attr_getguardsize(attr, &v);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getguardsize");
+    printf("%sGuard size          = %zu bytes\en", prefix, v);
+\&
+    s = pthread_attr_getstack(attr, &stkaddr, &v);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getstack");
+    printf("%sStack address       = %p\en", prefix, stkaddr);
+    printf("%sStack size          = %#zx bytes\en", prefix, v);
+}
+\&
+static void *
+thread_start(void *arg)
+{
+    int s;
+    pthread_attr_t gattr;
+\&
+    /* pthread_getattr_np() is a non\-standard GNU extension that
+       retrieves the attributes of the thread specified in its
+       first argument. */
+\&
+    s = pthread_getattr_np(pthread_self(), &gattr);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_getattr_np");
+\&
+    printf("Thread attributes:\en");
+    display_pthread_attr(&gattr, "\et");
+\&
+    exit(EXIT_SUCCESS);         /* Terminate all threads */
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    pthread_t thr;
+    pthread_attr_t attr;
+    pthread_attr_t *attrp;      /* NULL or &attr */
+    int s;
+\&
+    attrp = NULL;
+\&
+    /* If a command\-line argument was supplied, use it to set the
+       stack\-size attribute and set a few other thread attributes,
+       and set attrp pointing to thread attributes object. */
+\&
+    if (argc > 1) {
+        size_t stack_size;
+        void *sp;
+\&
+        attrp = &attr;
+\&
+        s = pthread_attr_init(&attr);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_init");
+\&
+        s = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_setdetachstate");
+\&
+        s = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_setinheritsched");
+\&
+        stack_size = strtoul(argv[1], NULL, 0);
+\&
+        s = posix_memalign(&sp, sysconf(_SC_PAGESIZE), stack_size);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "posix_memalign");
+\&
+        printf("posix_memalign() allocated at %p\en", sp);
+\&
+        s = pthread_attr_setstack(&attr, sp, stack_size);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_setstack");
+    }
+\&
+    s = pthread_create(&thr, attrp, &thread_start, NULL);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_create");
+\&
+    if (attrp != NULL) {
+        s = pthread_attr_destroy(attrp);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_destroy");
+    }
+\&
+    pause();    /* Terminates when other thread calls exit() */
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_attr_setaffinity_np (3),
+.BR pthread_attr_setdetachstate (3),
+.BR pthread_attr_setguardsize (3),
+.BR pthread_attr_setinheritsched (3),
+.BR pthread_attr_setschedparam (3),
+.BR pthread_attr_setschedpolicy (3),
+.BR pthread_attr_setscope (3),
+.BR pthread_attr_setsigmask_np (3),
+.BR pthread_attr_setstack (3),
+.BR pthread_attr_setstackaddr (3),
+.BR pthread_attr_setstacksize (3),
+.BR pthread_create (3),
+.BR pthread_getattr_np (3),
+.BR pthread_setattr_default_np (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_setaffinity_np.3 b/man/man3/pthread_attr_setaffinity_np.3
new file mode 100644
index 000000000..4d0df5763
--- /dev/null
+++ b/man/man3/pthread_attr_setaffinity_np.3
@@ -0,0 +1,120 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setaffinity_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setaffinity_np, pthread_attr_getaffinity_np \- set/get
+CPU affinity attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setaffinity_np(pthread_attr_t *" attr ,
+.BI "                   size_t " cpusetsize ", const cpu_set_t *" cpuset );
+.BI "int pthread_attr_getaffinity_np(const pthread_attr_t *" attr ,
+.BI "                   size_t " cpusetsize ", cpu_set_t *" cpuset );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setaffinity_np ()
+function
+sets the CPU affinity mask attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR cpuset .
+This attribute determines the CPU affinity mask
+of a thread created using the thread attributes object
+.IR attr .
+.P
+The
+.BR pthread_attr_getaffinity_np ()
+function
+returns the CPU affinity mask attribute of the thread attributes object
+referred to by
+.I attr
+in the buffer pointed to by
+.IR cpuset .
+.P
+The argument
+.I cpusetsize
+is the length (in bytes) of the buffer pointed to by
+.IR cpuset .
+Typically, this argument would be specified as
+.IR sizeof(cpu_set_t) .
+.P
+For more details on CPU affinity masks, see
+.BR sched_setaffinity (2).
+For a description of a set of macros
+that can be used to manipulate and inspect CPU sets, see
+.BR CPU_SET (3).
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.TP
+.B EINVAL
+.RB ( pthread_attr_setaffinity_np ())
+.I cpuset
+specified a CPU that was outside the set supported by the kernel.
+(The kernel configuration option
+.B CONFIG_NR_CPUS
+defines the range of the set supported by the kernel data type
+.\" cpumask_t
+used to represent CPU sets.)
+.\" The raw sched_getaffinity() system call returns the size (in bytes)
+.\" of the cpumask_t type.
+.TP
+.B EINVAL
+.RB ( pthread_attr_getaffinity_np ())
+A CPU in the affinity mask of the thread attributes object referred to by
+.I attr
+lies outside the range specified by
+.I cpusetsize
+(i.e.,
+.IR cpuset / cpusetsize
+is too small).
+.TP
+.B ENOMEM
+.RB ( pthread_attr_setaffinity_np ())
+Could not allocate memory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setaffinity_np (),
+.BR pthread_attr_getaffinity_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the names.
+.SH HISTORY
+glibc 2.3.4.
+.SH NOTES
+In glibc 2.3.3 only,
+versions of these functions were provided that did not have a
+.I cpusetsize
+argument.
+Instead the CPU set size given to the underlying system calls was always
+.IR sizeof(cpu_set_t) .
+.SH SEE ALSO
+.BR sched_setaffinity (2),
+.BR pthread_attr_init (3),
+.BR pthread_setaffinity_np (3),
+.BR cpuset (7),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_setdetachstate.3 b/man/man3/pthread_attr_setdetachstate.3
new file mode 100644
index 000000000..4c1828db7
--- /dev/null
+++ b/man/man3/pthread_attr_setdetachstate.3
@@ -0,0 +1,115 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setdetachstate 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setdetachstate, pthread_attr_getdetachstate \-
+set/get detach state attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setdetachstate(pthread_attr_t *" attr \
+", int " detachstate );
+.BI "int pthread_attr_getdetachstate(const pthread_attr_t *" attr ,
+.BI "                                int *" detachstate );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setdetachstate ()
+function sets the detach state attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR detachstate .
+The detach state attribute determines whether a thread created using
+the thread attributes object
+.I attr
+will be created in a joinable or a detached state.
+.P
+The following values may be specified in
+.IR detachstate :
+.TP
+.B PTHREAD_CREATE_DETACHED
+Threads that are created using
+.I attr
+will be created in a detached state.
+.TP
+.B PTHREAD_CREATE_JOINABLE
+Threads that are created using
+.I attr
+will be created in a joinable state.
+.P
+The default setting of the detach state attribute in a newly initialized
+thread attributes object is
+.BR PTHREAD_CREATE_JOINABLE .
+.P
+The
+.BR pthread_attr_getdetachstate ()
+returns the detach state attribute of the thread attributes object
+.I attr
+in the buffer pointed to by
+.IR detachstate .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.BR pthread_attr_setdetachstate ()
+can fail with the following error:
+.TP
+.B EINVAL
+An invalid value was specified in
+.IR detachstate .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setdetachstate (),
+.BR pthread_attr_getdetachstate ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+See
+.BR pthread_create (3)
+for more details on detached and joinable threads.
+.P
+A thread that is created in a joinable state should
+eventually either be joined using
+.BR pthread_join (3)
+or detached using
+.BR pthread_detach (3);
+see
+.BR pthread_create (3).
+.P
+It is an error to specify the thread ID of
+a thread that was created in a detached state
+in a later call to
+.BR pthread_detach (3)
+or
+.BR pthread_join (3).
+.SH EXAMPLES
+See
+.BR pthread_attr_init (3).
+.SH SEE ALSO
+.BR pthread_attr_init (3),
+.BR pthread_create (3),
+.BR pthread_detach (3),
+.BR pthread_join (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_setguardsize.3 b/man/man3/pthread_attr_setguardsize.3
new file mode 100644
index 000000000..de9e4f2b7
--- /dev/null
+++ b/man/man3/pthread_attr_setguardsize.3
@@ -0,0 +1,163 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setguardsize 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setguardsize, pthread_attr_getguardsize \- set/get guard size
+attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setguardsize(pthread_attr_t *" attr \
+", size_t " guardsize );
+.BI "int pthread_attr_getguardsize(const pthread_attr_t *restrict " attr ,
+.BI "                              size_t *restrict " guardsize );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setguardsize ()
+function sets the guard size attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR guardsize .
+.P
+If
+.I guardsize
+is greater than 0,
+then for each new thread created using
+.I attr
+the system allocates an additional region of at least
+.I guardsize
+bytes at the end of the thread's stack to act as the guard area
+for the stack (but see BUGS).
+.P
+If
+.I guardsize
+is 0, then new threads created with
+.I attr
+will not have a guard area.
+.P
+The default guard size is the same as the system page size.
+.P
+If the stack address attribute has been set in
+.I attr
+(using
+.BR pthread_attr_setstack (3)
+or
+.BR pthread_attr_setstackaddr (3)),
+meaning that the caller is allocating the thread's stack,
+then the guard size attribute is ignored
+(i.e., no guard area is created by the system):
+it is the application's responsibility to handle stack overflow
+(perhaps by using
+.BR mprotect (2)
+to manually define a guard area at the end of the stack
+that it has allocated).
+.P
+The
+.BR pthread_attr_getguardsize ()
+function returns the guard size attribute of the
+thread attributes object referred to by
+.I attr
+in the buffer pointed to by
+.IR guardsize .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+POSIX.1 documents an
+.B EINVAL
+error if
+.I attr
+or
+.I guardsize
+is invalid.
+On Linux these functions always succeed
+(but portable and future-proof applications should nevertheless
+handle a possible error return).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setguardsize (),
+.BR pthread_attr_getguardsize ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH NOTES
+A guard area consists of virtual memory pages that are protected
+to prevent read and write access.
+If a thread overflows its stack into the guard area,
+then, on most hard architectures, it receives a
+.B SIGSEGV
+signal, thus notifying it of the overflow.
+Guard areas start on page boundaries,
+and the guard size is internally rounded up to
+the system page size when creating a thread.
+(Nevertheless,
+.BR pthread_attr_getguardsize ()
+returns the guard size that was set by
+.BR pthread_attr_setguardsize ().)
+.P
+Setting a guard size of 0 may be useful to save memory
+in an application that creates many threads
+and knows that stack overflow can never occur.
+.P
+Choosing a guard size larger than the default size
+may be necessary for detecting stack overflows
+if a thread allocates large data structures on the stack.
+.SH BUGS
+As at glibc 2.8, the NPTL threading implementation includes
+the guard area within the stack size allocation,
+rather than allocating extra space at the end of the stack,
+as POSIX.1 requires.
+(This can result in an
+.B EINVAL
+error from
+.BR pthread_create (3)
+if the guard size value is too large,
+leaving no space for the actual stack.)
+.P
+The obsolete LinuxThreads implementation did the right thing,
+allocating extra space at the end of the stack for the guard area.
+.\" glibc includes the guardsize within the allocated stack size,
+.\" which looks pretty clearly to be in violation of POSIX.
+.\"
+.\" Filed bug, 22 Oct 2008:
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6973
+.\"
+.\" Older reports:
+.\" https//bugzilla.redhat.com/show_bug.cgi?id=435337
+.\" Reportedly, LinuxThreads did the right thing, allocating
+.\" extra space at the end of the stack:
+.\" http://sourceware.org/ml/libc-alpha/2008-05/msg00086.html
+.SH EXAMPLES
+See
+.BR pthread_getattr_np (3).
+.SH SEE ALSO
+.BR mmap (2),
+.BR mprotect (2),
+.BR pthread_attr_init (3),
+.BR pthread_attr_setstack (3),
+.BR pthread_attr_setstacksize (3),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_setinheritsched.3 b/man/man3/pthread_attr_setinheritsched.3
new file mode 100644
index 000000000..832f3b543
--- /dev/null
+++ b/man/man3/pthread_attr_setinheritsched.3
@@ -0,0 +1,140 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setinheritsched 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setinheritsched, pthread_attr_getinheritsched \- set/get
+inherit-scheduler attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setinheritsched(pthread_attr_t *" attr ,
+.BI "                                 int " inheritsched );
+.BI "int pthread_attr_getinheritsched(const pthread_attr_t *restrict " attr ,
+.BI "                                 int *restrict " inheritsched );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setinheritsched ()
+function sets the inherit-scheduler attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR inheritsched .
+The inherit-scheduler attribute determines whether a thread created using
+the thread attributes object
+.I attr
+will inherit its scheduling attributes from the calling thread
+or whether it will take them from
+.IR attr .
+.P
+The following scheduling attributes are affected by the
+inherit-scheduler attribute:
+scheduling policy
+.RB ( pthread_attr_setschedpolicy (3)),
+scheduling priority
+.RB ( pthread_attr_setschedparam (3)),
+and contention scope
+.RB ( pthread_attr_setscope (3)).
+.P
+The following values may be specified in
+.IR inheritsched :
+.TP
+.B PTHREAD_INHERIT_SCHED
+Threads that are created using
+.I attr
+inherit scheduling attributes from the creating thread;
+the scheduling attributes in
+.I attr
+are ignored.
+.TP
+.B PTHREAD_EXPLICIT_SCHED
+Threads that are created using
+.I attr
+take their scheduling attributes from the values specified
+by the attributes object.
+.\" FIXME Document the defaults for scheduler settings
+.P
+The default setting of the inherit-scheduler attribute in
+a newly initialized thread attributes object is
+.BR PTHREAD_INHERIT_SCHED .
+.P
+The
+.BR pthread_attr_getinheritsched ()
+returns the inherit-scheduler attribute of the thread attributes object
+.I attr
+in the buffer pointed to by
+.IR inheritsched .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.BR pthread_attr_setinheritsched ()
+can fail with the following error:
+.TP
+.B EINVAL
+Invalid value in
+.IR inheritsched .
+.P
+POSIX.1 also documents an optional
+.B ENOTSUP
+error ("attempt was made to set the attribute to an unsupported value") for
+.BR pthread_attr_setinheritsched ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setinheritsched (),
+.BR pthread_attr_getinheritsched ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.0.
+POSIX.1-2001.
+.SH BUGS
+As at glibc 2.8, if a thread attributes object is initialized using
+.BR pthread_attr_init (3),
+then the scheduling policy of the attributes object is set to
+.B SCHED_OTHER
+and the scheduling priority is set to 0.
+However, if the inherit-scheduler attribute is then set to
+.BR PTHREAD_EXPLICIT_SCHED ,
+then a thread created using the attribute object
+wrongly inherits its scheduling attributes from the creating thread.
+This bug does not occur if either the scheduling policy or
+scheduling priority attribute is explicitly set
+in the thread attributes object before calling
+.BR pthread_create (3).
+.\" FIXME . Track status of the following bug:
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=7007
+.SH EXAMPLES
+See
+.BR pthread_setschedparam (3).
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_attr_init (3),
+.BR pthread_attr_setschedparam (3),
+.BR pthread_attr_setschedpolicy (3),
+.BR pthread_attr_setscope (3),
+.BR pthread_create (3),
+.BR pthread_setschedparam (3),
+.BR pthread_setschedprio (3),
+.BR pthreads (7),
+.BR sched (7)
diff --git a/man/man3/pthread_attr_setschedparam.3 b/man/man3/pthread_attr_setschedparam.3
new file mode 100644
index 000000000..97df58a42
--- /dev/null
+++ b/man/man3/pthread_attr_setschedparam.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setschedparam 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setschedparam, pthread_attr_getschedparam \- set/get
+scheduling parameter attributes in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setschedparam(pthread_attr_t *restrict " attr ,
+.BI "                              const struct sched_param *restrict " param );
+.BI "int pthread_attr_getschedparam(const pthread_attr_t *restrict " attr ,
+.BI "                              struct sched_param *restrict " param );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setschedparam ()
+function sets the scheduling parameter attributes of the
+thread attributes object referred to by
+.I attr
+to the values specified in the buffer pointed to by
+.IR param .
+These attributes determine the scheduling parameters of
+a thread created using the thread attributes object
+.IR attr .
+.P
+The
+.BR pthread_attr_getschedparam ()
+returns the scheduling parameter attributes of the thread attributes object
+.I attr
+in the buffer pointed to by
+.IR param .
+.P
+Scheduling parameters are maintained in the following structure:
+.P
+.in +4n
+.EX
+struct sched_param {
+    int sched_priority;     /* Scheduling priority */
+};
+.EE
+.in
+.P
+As can be seen, only one scheduling parameter is supported.
+For details of the permitted ranges for scheduling priorities
+in each scheduling policy, see
+.BR sched (7).
+.P
+In order for the parameter setting made by
+.BR pthread_attr_setschedparam ()
+to have effect when calling
+.BR pthread_create (3),
+the caller must use
+.BR pthread_attr_setinheritsched (3)
+to set the inherit-scheduler attribute of the attributes object
+.I attr
+to
+.BR PTHREAD_EXPLICIT_SCHED .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.BR pthread_attr_setschedparam ()
+can fail with the following error:
+.TP
+.B EINVAL
+The priority specified in
+.I param
+does not make sense for the current scheduling policy of
+.IR attr .
+.P
+POSIX.1 also documents an
+.B ENOTSUP
+error for
+.BR pthread_attr_setschedparam ().
+This value is never returned on Linux
+(but portable and future-proof applications should nevertheless
+handle this error return value).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setschedparam (),
+.BR pthread_attr_getschedparam ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+glibc 2.0.
+.SH NOTES
+See
+.BR pthread_attr_setschedpolicy (3)
+for a list of the thread scheduling policies supported on Linux.
+.SH EXAMPLES
+See
+.BR pthread_setschedparam (3).
+.SH SEE ALSO
+.ad l
+.nh
+.BR sched_get_priority_min (2),
+.BR pthread_attr_init (3),
+.BR pthread_attr_setinheritsched (3),
+.BR pthread_attr_setschedpolicy (3),
+.BR pthread_create (3),
+.BR pthread_setschedparam (3),
+.BR pthread_setschedprio (3),
+.BR pthreads (7),
+.BR sched (7)
diff --git a/man/man3/pthread_attr_setschedpolicy.3 b/man/man3/pthread_attr_setschedpolicy.3
new file mode 100644
index 000000000..f2575cf78
--- /dev/null
+++ b/man/man3/pthread_attr_setschedpolicy.3
@@ -0,0 +1,112 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setschedpolicy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setschedpolicy, pthread_attr_getschedpolicy \- set/get
+scheduling policy attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setschedpolicy(pthread_attr_t *" attr ", int " policy );
+.BI "int pthread_attr_getschedpolicy(const pthread_attr_t *restrict " attr ,
+.BI "                                int *restrict " policy );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setschedpolicy ()
+function sets the scheduling policy attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR policy .
+This attribute determines the scheduling policy of
+a thread created using the thread attributes object
+.IR attr .
+.P
+The supported values for
+.I policy
+are
+.BR SCHED_FIFO ,
+.BR SCHED_RR ,
+and
+.BR SCHED_OTHER ,
+with the semantics described in
+.BR sched (7).
+.\" FIXME . pthread_setschedparam() places no restriction on the policy,
+.\" but pthread_attr_setschedpolicy() restricts policy to RR/FIFO/OTHER
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=7013
+.P
+The
+.BR pthread_attr_getschedpolicy ()
+returns the scheduling policy attribute of the thread attributes object
+.I attr
+in the buffer pointed to by
+.IR policy .
+.P
+In order for the policy setting made by
+.BR pthread_attr_setschedpolicy ()
+to have effect when calling
+.BR pthread_create (3),
+the caller must use
+.BR pthread_attr_setinheritsched (3)
+to set the inherit-scheduler attribute of the attributes object
+.I attr
+to
+.BR PTHREAD_EXPLICIT_SCHED .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.BR pthread_attr_setschedpolicy ()
+can fail with the following error:
+.TP
+.B EINVAL
+Invalid value in
+.IR policy .
+.P
+POSIX.1 also documents an optional
+.B ENOTSUP
+error ("attempt was made to set the attribute to an unsupported value") for
+.BR pthread_attr_setschedpolicy ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setschedpolicy (),
+.BR pthread_attr_getschedpolicy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.0.
+POSIX.1-2001.
+.SH EXAMPLES
+See
+.BR pthread_setschedparam (3).
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_attr_init (3),
+.BR pthread_attr_setinheritsched (3),
+.BR pthread_attr_setschedparam (3),
+.BR pthread_create (3),
+.BR pthread_setschedparam (3),
+.BR pthread_setschedprio (3),
+.BR pthreads (7),
+.BR sched (7)
diff --git a/man/man3/pthread_attr_setscope.3 b/man/man3/pthread_attr_setscope.3
new file mode 100644
index 000000000..b48d0dd7a
--- /dev/null
+++ b/man/man3/pthread_attr_setscope.3
@@ -0,0 +1,139 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setscope 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setscope, pthread_attr_getscope \- set/get contention scope
+attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setscope(pthread_attr_t *" attr ", int " scope );
+.BI "int pthread_attr_getscope(const pthread_attr_t *restrict " attr ,
+.BI "                          int *restrict " scope );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setscope ()
+function sets the contention scope attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR scope .
+The contention scope attribute defines the set of threads
+against which a thread competes for resources such as the CPU.
+POSIX.1 specifies two possible values for
+.IR scope :
+.TP
+.B PTHREAD_SCOPE_SYSTEM
+The thread competes for resources with all other threads
+in all processes on the system that are in the same scheduling
+allocation domain (a group of one or more processors).
+.B PTHREAD_SCOPE_SYSTEM
+threads are scheduled relative to one another
+according to their scheduling policy and priority.
+.TP
+.B PTHREAD_SCOPE_PROCESS
+The thread competes for resources with all other threads
+in the same process that were also created with the
+.B PTHREAD_SCOPE_PROCESS
+contention scope.
+.B PTHREAD_SCOPE_PROCESS
+threads are scheduled relative to other threads in the process
+according to their scheduling policy and priority.
+POSIX.1 leaves it unspecified how these threads contend
+with other threads in other process on the system or
+with other threads in the same process that
+were created with the
+.B PTHREAD_SCOPE_SYSTEM
+contention scope.
+.P
+POSIX.1 requires that an implementation support at least one of these
+contention scopes.
+Linux supports
+.BR PTHREAD_SCOPE_SYSTEM ,
+but not
+.BR PTHREAD_SCOPE_PROCESS .
+.P
+On systems that support multiple contention scopes, then,
+in order for the parameter setting made by
+.BR pthread_attr_setscope ()
+to have effect when calling
+.BR pthread_create (3),
+the caller must use
+.BR pthread_attr_setinheritsched (3)
+to set the inherit-scheduler attribute of the attributes object
+.I attr
+to
+.BR PTHREAD_EXPLICIT_SCHED .
+.P
+The
+.BR pthread_attr_getscope ()
+function returns the contention scope attribute of the
+thread attributes object referred to by
+.I attr
+in the buffer pointed to by
+.IR scope .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.BR pthread_attr_setscope ()
+can fail with the following errors:
+.TP
+.B EINVAL
+An invalid value was specified in
+.IR scope .
+.TP
+.B ENOTSUP
+.I scope
+specified the value
+.BR PTHREAD_SCOPE_PROCESS ,
+which is not supported on Linux.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setscope (),
+.BR pthread_attr_getscope ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The
+.B PTHREAD_SCOPE_SYSTEM
+contention scope typically indicates that a user-space thread is
+bound directly to a single kernel-scheduling entity.
+This is the case on Linux for the obsolete LinuxThreads implementation
+and the modern NPTL implementation,
+which are both 1:1 threading implementations.
+.P
+POSIX.1 specifies that the default contention scope is
+implementation-defined.
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_attr_init (3),
+.BR pthread_attr_setaffinity_np (3),
+.BR pthread_attr_setinheritsched (3),
+.BR pthread_attr_setschedparam (3),
+.BR pthread_attr_setschedpolicy (3),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_setsigmask_np.3 b/man/man3/pthread_attr_setsigmask_np.3
new file mode 100644
index 000000000..ab50568f2
--- /dev/null
+++ b/man/man3/pthread_attr_setsigmask_np.3
@@ -0,0 +1,130 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setsigmask_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setsigmask_np, pthread_attr_getsigmask_np \- set/get
+signal mask attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setsigmask_np(pthread_attr_t *" attr ,
+.BI "                               const sigset_t *" sigmask );
+.BI "int pthread_attr_getsigmask_np(const pthread_attr_t *" attr ,
+.BI "                               sigset_t *" sigmask );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setsigmask_np ()
+function sets the signal mask attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR *sigmask .
+If
+.I sigmask
+is specified as NULL, then any existing signal mask attribute in
+.I attr
+is unset.
+.P
+The
+.BR pthread_attr_getsigmask_np ()
+function returns the signal mask attribute of the thread attributes object
+referred to by
+.I attr
+in the buffer pointed to by
+.IR sigmask .
+If the signal mask attribute is currently unset,
+then this function returns the special value
+.B PTHREAD_ATTR_NO_SIGMASK_NP
+as its result.
+.SH RETURN VALUE
+The
+.BR pthread_attr_setsigmask_np ()
+function returns 0 on success, or a nonzero error number on failure.
+.P
+the
+.BR pthread_attr_getsigmask_np ()
+function returns either 0 or
+.BR PTHREAD_ATTR_NO_SIGMASK_NP .
+When 0 is returned, the signal mask attribute is returned via
+.IR sigmask .
+A return value of
+.B PTHREAD_ATTR_NO_SIGMASK_NP
+indicates that the signal mask attribute is not set in
+.IR attr .
+.P
+On error, these functions return a positive error number.
+.SH ERRORS
+.TP
+.B ENOMEM
+.RB ( pthread_attr_setsigmask_np ())
+Could not allocate memory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setsigmask_np (),
+.BR pthread_attr_getsigmask_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the names.
+.SH HISTORY
+glibc 2.32.
+.SH NOTES
+The signal mask attribute determines the signal mask that will be assigned to
+a thread created using the thread attributes object
+.IR attr .
+If this attribute is not set, then a thread created using
+.I attr
+will inherit a copy of the creating thread's signal mask.
+.P
+For more details on signal masks, see
+.BR sigprocmask (2).
+For a description of a set of macros
+that can be used to manipulate and inspect signal sets, see
+.BR sigsetops (3).
+.P
+In the absence of
+.BR pthread_attr_setsigmask_np ()
+it is possible to create a thread with a desired signal mask as follows:
+.IP \[bu] 3
+The creating thread uses
+.BR pthread_sigmask (3)
+to save its current signal mask and set its mask to block all signals.
+.IP \[bu]
+The new thread is then created using
+.BR pthread_create ();
+the new thread will inherit the creating thread's signal mask.
+.IP \[bu]
+The new thread sets its signal mask to the desired value using
+.BR pthread_sigmask (3).
+.IP \[bu]
+The creating thread restores its signal mask to the original value.
+.P
+Following the above steps,
+there is no possibility for the new thread to receive a signal
+before it has adjusted its signal mask to the desired value.
+.SH SEE ALSO
+.BR sigprocmask (2),
+.BR pthread_attr_init (3),
+.BR pthread_sigmask (3),
+.BR pthreads (7),
+.BR signal (7)
diff --git a/man/man3/pthread_attr_setstack.3 b/man/man3/pthread_attr_setstack.3
new file mode 100644
index 000000000..f783b03a5
--- /dev/null
+++ b/man/man3/pthread_attr_setstack.3
@@ -0,0 +1,164 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setstack 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setstack, pthread_attr_getstack \- set/get stack
+attributes in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setstack(pthread_attr_t *" attr ,
+.BI "                          void " stackaddr [. stacksize ],
+.BI "                          size_t " stacksize );
+.BI "int pthread_attr_getstack(const pthread_attr_t *restrict " attr ,
+.BI "                          void **restrict " stackaddr ,
+.BI "                          size_t *restrict " stacksize );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_attr_getstack (),
+.BR pthread_attr_setstack ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setstack ()
+function sets the stack address and stack size attributes of the
+thread attributes object referred to by
+.I attr
+to the values specified in
+.I stackaddr
+and
+.IR stacksize ,
+respectively.
+These attributes specify the location and size of the stack that should
+be used by a thread that is created using the thread attributes object
+.IR attr .
+.P
+.I stackaddr
+should point to the lowest addressable byte of a buffer of
+.I stacksize
+bytes that was allocated by the caller.
+The pages of the allocated buffer should be both readable and writable.
+.P
+The
+.BR pthread_attr_getstack ()
+function returns the stack address and stack size attributes of the
+thread attributes object referred to by
+.I attr
+in the buffers pointed to by
+.I stackaddr
+and
+.IR stacksize ,
+respectively.
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.BR pthread_attr_setstack ()
+can fail with the following error:
+.TP
+.B EINVAL
+.I stacksize
+is less than
+.B PTHREAD_STACK_MIN
+(16384) bytes.
+On some systems, this error may also occur if
+.I stackaddr
+or
+.I stackaddr\~+\~stacksize
+is not suitably aligned.
+.P
+POSIX.1 also documents an
+.B EACCES
+error if the stack area described by
+.I stackaddr
+and
+.I stacksize
+is not both readable and writable by the caller.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setstack (),
+.BR pthread_attr_getstack ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.SH NOTES
+These functions are provided for applications that must ensure that
+a thread's stack is placed in a particular location.
+For most applications, this is not necessary,
+and the use of these functions should be avoided.
+(Use
+.BR pthread_attr_setstacksize (3)
+if an application simply requires a stack size other than the default.)
+.P
+When an application employs
+.BR pthread_attr_setstack (),
+it takes over the responsibility of allocating the stack.
+Any guard size value that was set using
+.BR pthread_attr_setguardsize (3)
+is ignored.
+If deemed necessary,
+it is the application's responsibility to allocate a guard area
+(one or more pages protected against reading and writing)
+to handle the possibility of stack overflow.
+.P
+The address specified in
+.I stackaddr
+should be suitably aligned:
+for full portability, align it on a page boundary
+.RI ( sysconf(_SC_PAGESIZE) ).
+.BR posix_memalign (3)
+may be useful for allocation.
+Probably,
+.I stacksize
+should also be a multiple of the system page size.
+.P
+If
+.I attr
+is used to create multiple threads, then the caller must change the
+stack address attribute between calls to
+.BR pthread_create (3);
+otherwise, the threads will attempt to use the same memory area
+for their stacks, and chaos will ensue.
+.SH EXAMPLES
+See
+.BR pthread_attr_init (3).
+.SH SEE ALSO
+.ad l
+.nh
+.BR mmap (2),
+.BR mprotect (2),
+.BR posix_memalign (3),
+.BR pthread_attr_init (3),
+.BR pthread_attr_setguardsize (3),
+.BR pthread_attr_setstackaddr (3),
+.BR pthread_attr_setstacksize (3),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_setstackaddr.3 b/man/man3/pthread_attr_setstackaddr.3
new file mode 100644
index 000000000..7f72b0f59
--- /dev/null
+++ b/man/man3/pthread_attr_setstackaddr.3
@@ -0,0 +1,115 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setstackaddr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setstackaddr, pthread_attr_getstackaddr \-
+set/get stack address attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.B [[deprecated]]
+.BI "int pthread_attr_setstackaddr(pthread_attr_t *" attr \
+", void *" stackaddr );
+.B [[deprecated]]
+.BI "int pthread_attr_getstackaddr(const pthread_attr_t *restrict " attr ,
+.BI "                              void **restrict " stackaddr );
+.fi
+.SH DESCRIPTION
+These functions are obsolete:
+.B do not use them.
+Use
+.BR pthread_attr_setstack (3)
+and
+.BR pthread_attr_getstack (3)
+instead.
+.P
+The
+.BR pthread_attr_setstackaddr ()
+function sets the stack address attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR stackaddr .
+This attribute specifies the location of the stack that should
+be used by a thread that is created using the thread attributes object
+.IR attr .
+.P
+.I stackaddr
+should point to a buffer of at least
+.B PTHREAD_STACK_MIN
+bytes that was allocated by the caller.
+The pages of the allocated buffer should be both readable and writable.
+.P
+The
+.BR pthread_attr_getstackaddr ()
+function returns the stack address attribute of the
+thread attributes object referred to by
+.I attr
+in the buffer pointed to by
+.IR stackaddr .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+No errors are defined
+(but applications should nevertheless
+handle a possible error return).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setstackaddr (),
+.BR pthread_attr_getstackaddr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.1.
+Marked obsolete in POSIX.1-2001.
+Removed in POSIX.1-2008.
+.SH NOTES
+.I Do not use these functions!
+They cannot be portably used, since they provide no way of specifying
+the direction of growth or the range of the stack.
+For example, on architectures with a stack that grows downward,
+.I stackaddr
+specifies the next address past the
+.I highest
+address of the allocated stack area.
+However, on architectures with a stack that grows upward,
+.I stackaddr
+specifies the
+.I lowest
+address in the allocated stack area.
+By contrast, the
+.I stackaddr
+used by
+.BR pthread_attr_setstack (3)
+and
+.BR pthread_attr_getstack (3),
+is always a pointer to the lowest address in the allocated stack area
+(and the
+.I stacksize
+argument specifies the range of the stack).
+.SH SEE ALSO
+.BR pthread_attr_init (3),
+.BR pthread_attr_setstack (3),
+.BR pthread_attr_setstacksize (3),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_attr_setstacksize.3 b/man/man3/pthread_attr_setstacksize.3
new file mode 100644
index 000000000..61816cc41
--- /dev/null
+++ b/man/man3/pthread_attr_setstacksize.3
@@ -0,0 +1,114 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_attr_setstacksize 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_attr_setstacksize, pthread_attr_getstacksize \- set/get stack size
+attribute in thread attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_attr_setstacksize(pthread_attr_t *" attr \
+", size_t " stacksize );
+.BI "int pthread_attr_getstacksize(const pthread_attr_t *restrict " attr ,
+.BI "                              size_t *restrict " stacksize );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_attr_setstacksize ()
+function sets the stack size attribute of the
+thread attributes object referred to by
+.I attr
+to the value specified in
+.IR stacksize .
+.P
+The stack size attribute determines the minimum size (in bytes) that
+will be allocated for threads created using the thread attributes object
+.IR attr .
+.P
+The
+.BR pthread_attr_getstacksize ()
+function returns the stack size attribute of the
+thread attributes object referred to by
+.I attr
+in the buffer pointed to by
+.IR stacksize .
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.BR pthread_attr_setstacksize ()
+can fail with the following error:
+.TP
+.B EINVAL
+The stack size is less than
+.B PTHREAD_STACK_MIN
+(16384) bytes.
+.P
+On some systems,
+.\" e.g., MacOS
+.BR pthread_attr_setstacksize ()
+can fail with the error
+.B EINVAL
+if
+.I stacksize
+is not a multiple of the system page size.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_attr_setstacksize (),
+.BR pthread_attr_getstacksize ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+These functions are provided since glibc 2.1.
+.SH STANDARDS
+POSIX.1-2001, POSIX.1-2008.
+.SH NOTES
+For details on the default stack size of new threads, see
+.BR pthread_create (3).
+.P
+A thread's stack size is fixed at the time of thread creation.
+Only the main thread can dynamically grow its stack.
+.P
+The
+.BR pthread_attr_setstack (3)
+function allows an application to set both the size and location
+of a caller-allocated stack that is to be used by a thread.
+.SH BUGS
+As at glibc 2.8,
+if the specified
+.I stacksize
+is not a multiple of
+.B STACK_ALIGN
+(16 bytes on most architectures), it may be rounded
+.IR downward ,
+in violation of POSIX.1, which says that the allocated stack will
+be at least
+.I stacksize
+bytes.
+.SH EXAMPLES
+See
+.BR pthread_create (3).
+.SH SEE ALSO
+.BR getrlimit (2),
+.BR pthread_attr_init (3),
+.BR pthread_attr_setguardsize (3),
+.BR pthread_attr_setstack (3),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_cancel.3 b/man/man3/pthread_cancel.3
new file mode 100644
index 000000000..3fef2f1c5
--- /dev/null
+++ b/man/man3/pthread_cancel.3
@@ -0,0 +1,237 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_cancel 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_cancel \- send a cancelation request to a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_cancel(pthread_t " thread );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_cancel ()
+function sends a cancelation request to the thread
+.IR thread .
+Whether and when the target thread
+reacts to the cancelation request depends on
+two attributes that are under the control of that thread:
+its cancelability
+.I state
+and
+.IR type .
+.P
+A thread's cancelability state, determined by
+.BR pthread_setcancelstate (3),
+can be
+.I enabled
+(the default for new threads) or
+.IR disabled .
+If a thread has disabled cancelation,
+then a cancelation request remains queued until the thread
+enables cancelation.
+If a thread has enabled cancelation,
+then its cancelability type determines when cancelation occurs.
+.P
+A thread's cancelation type, determined by
+.BR pthread_setcanceltype (3),
+may be either
+.I asynchronous
+or
+.I deferred
+(the default for new threads).
+Asynchronous cancelability
+means that the thread can be canceled at any time
+(usually immediately, but the system does not guarantee this).
+Deferred cancelability means that cancelation will be delayed until
+the thread next calls a function that is a
+.IR "cancelation point" .
+A list of functions that are or may be cancelation points is provided in
+.BR pthreads (7).
+.P
+When a cancelation requested is acted on, the following steps occur for
+.I thread
+(in this order):
+.IP (1) 5
+Cancelation clean-up handlers are popped
+(in the reverse of the order in which they were pushed) and called.
+(See
+.BR pthread_cleanup_push (3).)
+.IP (2)
+Thread-specific data destructors are called,
+in an unspecified order.
+(See
+.BR pthread_key_create (3).)
+.IP (3)
+The thread is terminated.
+(See
+.BR pthread_exit (3).)
+.P
+The above steps happen asynchronously with respect to the
+.BR pthread_cancel ()
+call;
+the return status of
+.BR pthread_cancel ()
+merely informs the caller whether the cancelation request
+was successfully queued.
+.P
+After a canceled thread has terminated,
+a join with that thread using
+.BR pthread_join (3)
+obtains
+.B PTHREAD_CANCELED
+as the thread's exit status.
+(Joining with a thread is the only way to know that cancelation
+has completed.)
+.SH RETURN VALUE
+On success,
+.BR pthread_cancel ()
+returns 0;
+on error, it returns a nonzero error number.
+.SH ERRORS
+.TP
+.B ESRCH
+No thread with the ID
+.I thread
+could be found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_cancel ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On Linux, cancelation is implemented using signals.
+Under the NPTL threading implementation,
+the first real-time signal (i.e., signal 32) is used for this purpose.
+On LinuxThreads, the second real-time signal is used,
+if real-time signals are available, otherwise
+.B SIGUSR2
+is used.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.0
+POSIX.1-2001.
+.SH EXAMPLES
+The program below creates a thread and then cancels it.
+The main thread joins with the canceled thread to check
+that its exit status was
+.BR PTHREAD_CANCELED .
+The following shell session shows what happens when we run the program:
+.P
+.in +4n
+.EX
+$ ./a.out
+thread_func(): started; cancelation disabled
+main(): sending cancelation request
+thread_func(): about to enable cancelation
+main(): thread was canceled
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_cancel.c)
+.EX
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static void *
+thread_func(void *ignored_argument)
+{
+    int s;
+\&
+    /* Disable cancelation for a while, so that we don\[aq]t
+       immediately react to a cancelation request. */
+\&
+    s = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_setcancelstate");
+\&
+    printf("%s(): started; cancelation disabled\en", __func__);
+    sleep(5);
+    printf("%s(): about to enable cancelation\en", __func__);
+\&
+    s = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_setcancelstate");
+\&
+    /* sleep() is a cancelation point. */
+\&
+    sleep(1000);        /* Should get canceled while we sleep */
+\&
+    /* Should never get here. */
+\&
+    printf("%s(): not canceled!\en", __func__);
+    return NULL;
+}
+\&
+int
+main(void)
+{
+    pthread_t thr;
+    void *res;
+    int s;
+\&
+    /* Start a thread and then send it a cancelation request. */
+\&
+    s = pthread_create(&thr, NULL, &thread_func, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_create");
+\&
+    sleep(2);           /* Give thread a chance to get started */
+\&
+    printf("%s(): sending cancelation request\en", __func__);
+    s = pthread_cancel(thr);
+    if (s != 0)
+        handle_error_en(s, "pthread_cancel");
+\&
+    /* Join with thread to see what its exit status was. */
+\&
+    s = pthread_join(thr, &res);
+    if (s != 0)
+        handle_error_en(s, "pthread_join");
+\&
+    if (res == PTHREAD_CANCELED)
+        printf("%s(): thread was canceled\en", __func__);
+    else
+        printf("%s(): thread wasn\[aq]t canceled (shouldn\[aq]t happen!)\en",
+               __func__);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_cleanup_push (3),
+.BR pthread_create (3),
+.BR pthread_exit (3),
+.BR pthread_join (3),
+.BR pthread_key_create (3),
+.BR pthread_setcancelstate (3),
+.BR pthread_setcanceltype (3),
+.BR pthread_testcancel (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_cleanup_pop.3 b/man/man3/pthread_cleanup_pop.3
new file mode 100644
index 000000000..fb0e68bc9
--- /dev/null
+++ b/man/man3/pthread_cleanup_pop.3
@@ -0,0 +1 @@
+.so man3/pthread_cleanup_push.3
diff --git a/man/man3/pthread_cleanup_pop_restore_np.3 b/man/man3/pthread_cleanup_pop_restore_np.3
new file mode 100644
index 000000000..c47e20a06
--- /dev/null
+++ b/man/man3/pthread_cleanup_pop_restore_np.3
@@ -0,0 +1 @@
+.so man3/pthread_cleanup_push_defer_np.3
diff --git a/man/man3/pthread_cleanup_push.3 b/man/man3/pthread_cleanup_push.3
new file mode 100644
index 000000000..7026929a8
--- /dev/null
+++ b/man/man3/pthread_cleanup_push.3
@@ -0,0 +1,319 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_cleanup_push 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_cleanup_push, pthread_cleanup_pop \- push and pop
+thread cancelation clean-up handlers
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "void pthread_cleanup_push(void (*" routine ")(void *), void *" arg );
+.BI "void pthread_cleanup_pop(int " execute );
+.fi
+.SH DESCRIPTION
+These functions manipulate the calling thread's stack of
+thread-cancelation clean-up handlers.
+A clean-up handler is a function that is automatically executed
+when a thread is canceled (or in various other circumstances
+described below);
+it might, for example, unlock a mutex so that
+it becomes available to other threads in the process.
+.P
+The
+.BR pthread_cleanup_push ()
+function pushes
+.I routine
+onto the top of the stack of clean-up handlers.
+When
+.I routine
+is later invoked, it will be given
+.I arg
+as its argument.
+.P
+The
+.BR pthread_cleanup_pop ()
+function removes the routine at the top of the stack of clean-up handlers,
+and optionally executes it if
+.I execute
+is nonzero.
+.P
+A cancelation clean-up handler is popped from the stack
+and executed in the following circumstances:
+.IP \[bu] 3
+When a thread is canceled,
+all of the stacked clean-up handlers are popped and executed in
+the reverse of the order in which they were pushed onto the stack.
+.IP \[bu]
+When a thread terminates by calling
+.BR pthread_exit (3),
+all clean-up handlers are executed as described in the preceding point.
+(Clean-up handlers are
+.I not
+called if the thread terminates by
+performing a
+.I return
+from the thread start function.)
+.IP \[bu]
+When a thread calls
+.BR pthread_cleanup_pop ()
+with a nonzero
+.I execute
+argument, the top-most clean-up handler is popped and executed.
+.P
+POSIX.1 permits
+.BR pthread_cleanup_push ()
+and
+.BR pthread_cleanup_pop ()
+to be implemented as macros that expand to text
+containing \[aq]\fB{\fP\[aq] and \[aq]\fB}\fP\[aq], respectively.
+For this reason, the caller must ensure that calls to these
+functions are paired within the same function,
+and at the same lexical nesting level.
+(In other words, a clean-up handler is established only
+during the execution of a specified section of code.)
+.P
+Calling
+.BR longjmp (3)
+.RB ( siglongjmp (3))
+produces undefined results if any call has been made to
+.BR pthread_cleanup_push ()
+or
+.BR pthread_cleanup_pop ()
+without the matching call of the pair since the jump buffer
+was filled by
+.BR setjmp (3)
+.RB ( sigsetjmp (3)).
+Likewise, calling
+.BR longjmp (3)
+.RB ( siglongjmp (3))
+from inside a clean-up handler produces undefined results
+unless the jump buffer was also filled by
+.BR setjmp (3)
+.RB ( sigsetjmp (3))
+inside the handler.
+.SH RETURN VALUE
+These functions do not return a value.
+.SH ERRORS
+There are no errors.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_cleanup_push (),
+.BR pthread_cleanup_pop ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On glibc, the
+.BR pthread_cleanup_push ()
+and
+.BR pthread_cleanup_pop ()
+functions
+.I are
+implemented as macros that expand to text
+containing \[aq]\fB{\fP\[aq] and \[aq]\fB}\fP\[aq], respectively.
+This means that variables declared within the scope of
+paired calls to these functions will be visible within only that scope.
+.P
+POSIX.1
+.\" The text was actually added in the 2004 TC2
+says that the effect of using
+.IR return ,
+.IR break ,
+.IR continue ,
+or
+.I goto
+to prematurely leave a block bracketed
+.BR pthread_cleanup_push ()
+and
+.BR pthread_cleanup_pop ()
+is undefined.
+Portable applications should avoid doing this.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+glibc 2.0.
+.SH EXAMPLES
+The program below provides a simple example of the use of the functions
+described in this page.
+The program creates a thread that executes a loop bracketed by
+.BR pthread_cleanup_push ()
+and
+.BR pthread_cleanup_pop ().
+This loop increments a global variable,
+.IR cnt ,
+once each second.
+Depending on what command-line arguments are supplied,
+the main thread sends the other thread a cancelation request,
+or sets a global variable that causes the other thread
+to exit its loop and terminate normally (by doing a
+.IR return ).
+.P
+In the following shell session,
+the main thread sends a cancelation request to the other thread:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+New thread started
+cnt = 0
+cnt = 1
+Canceling thread
+Called clean\-up handler
+Thread was canceled; cnt = 0
+.EE
+.in
+.P
+From the above, we see that the thread was canceled,
+and that the cancelation clean-up handler was called
+and it reset the value of the global variable
+.I cnt
+to 0.
+.P
+In the next run, the main program sets a
+global variable that causes other thread to terminate normally:
+.P
+.in +4n
+.EX
+$ \fB./a.out x\fP
+New thread started
+cnt = 0
+cnt = 1
+Thread terminated normally; cnt = 2
+.EE
+.in
+.P
+From the above, we see that the clean-up handler was not executed (because
+.I cleanup_pop_arg
+was 0), and therefore the value of
+.I cnt
+was not reset.
+.P
+In the next run, the main program sets a global variable that
+causes the other thread to terminate normally,
+and supplies a nonzero value for
+.IR cleanup_pop_arg :
+.P
+.in +4n
+.EX
+$ \fB./a.out x 1\fP
+New thread started
+cnt = 0
+cnt = 1
+Called clean\-up handler
+Thread terminated normally; cnt = 0
+.EE
+.in
+.P
+In the above, we see that although the thread was not canceled,
+the clean-up handler was executed, because the argument given to
+.BR pthread_cleanup_pop ()
+was nonzero.
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_cleanup_push.c)
+.EX
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static int done = 0;
+static int cleanup_pop_arg = 0;
+static int cnt = 0;
+\&
+static void
+cleanup_handler(void *arg)
+{
+    printf("Called clean\-up handler\en");
+    cnt = 0;
+}
+\&
+static void *
+thread_start(void *arg)
+{
+    time_t curr;
+\&
+    printf("New thread started\en");
+\&
+    pthread_cleanup_push(cleanup_handler, NULL);
+\&
+    curr = time(NULL);
+\&
+    while (!done) {
+        pthread_testcancel();           /* A cancelation point */
+        if (curr < time(NULL)) {
+            curr = time(NULL);
+            printf("cnt = %d\en", cnt);  /* A cancelation point */
+            cnt++;
+        }
+    }
+\&
+    pthread_cleanup_pop(cleanup_pop_arg);
+    return NULL;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    pthread_t thr;
+    int s;
+    void *res;
+\&
+    s = pthread_create(&thr, NULL, thread_start, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_create");
+\&
+    sleep(2);           /* Allow new thread to run a while */
+\&
+    if (argc > 1) {
+        if (argc > 2)
+            cleanup_pop_arg = atoi(argv[2]);
+        done = 1;
+\&
+    } else {
+        printf("Canceling thread\en");
+        s = pthread_cancel(thr);
+        if (s != 0)
+            handle_error_en(s, "pthread_cancel");
+    }
+\&
+    s = pthread_join(thr, &res);
+    if (s != 0)
+        handle_error_en(s, "pthread_join");
+\&
+    if (res == PTHREAD_CANCELED)
+        printf("Thread was canceled; cnt = %d\en", cnt);
+    else
+        printf("Thread terminated normally; cnt = %d\en", cnt);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR pthread_cancel (3),
+.BR pthread_cleanup_push_defer_np (3),
+.BR pthread_setcancelstate (3),
+.BR pthread_testcancel (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_cleanup_push_defer_np.3 b/man/man3/pthread_cleanup_push_defer_np.3
new file mode 100644
index 000000000..f448a1896
--- /dev/null
+++ b/man/man3/pthread_cleanup_push_defer_np.3
@@ -0,0 +1,100 @@
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_cleanup_push_defer_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_cleanup_push_defer_np, pthread_cleanup_pop_restore_np \- push and pop
+thread cancelation clean-up handlers while saving cancelability type
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "void pthread_cleanup_push_defer_np(void (*" routine ")(void *), void *" arg );
+.BI "void pthread_cleanup_pop_restore_np(int " execute );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_cleanup_push_defer_np (),
+.BR pthread_cleanup_pop_defer_np ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+These functions are the same as
+.BR pthread_cleanup_push (3)
+and
+.BR pthread_cleanup_pop (3),
+except for the differences noted on this page.
+.P
+Like
+.BR pthread_cleanup_push (3),
+.BR pthread_cleanup_push_defer_np ()
+pushes
+.I routine
+onto the thread's stack of cancelation clean-up handlers.
+In addition, it also saves the thread's current cancelability type,
+and sets the cancelability type to "deferred" (see
+.BR pthread_setcanceltype (3));
+this ensures that cancelation clean-up will occur
+even if the thread's cancelability type was "asynchronous"
+before the call.
+.P
+Like
+.BR pthread_cleanup_pop (3),
+.BR pthread_cleanup_pop_restore_np ()
+pops the top-most clean-up handler from the thread's
+stack of cancelation clean-up handlers.
+In addition, it restores the thread's cancelability
+type to its value at the time of the matching
+.BR pthread_cleanup_push_defer_np ().
+.P
+The caller must ensure that calls to these
+functions are paired within the same function,
+and at the same lexical nesting level.
+Other restrictions apply, as described in
+.BR pthread_cleanup_push (3).
+.P
+This sequence of calls:
+.P
+.in +4n
+.EX
+pthread_cleanup_push_defer_np(routine, arg);
+pthread_cleanup_pop_restore_np(execute);
+.EE
+.in
+.P
+is equivalent to (but shorter and more efficient than):
+.P
+.\" As far as I can see, LinuxThreads reverses the two substeps
+.\" in the push and pop below.
+.in +4n
+.EX
+int oldtype;
+\&
+pthread_cleanup_push(routine, arg);
+pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, &oldtype);
+\&...
+pthread_setcanceltype(oldtype, NULL);
+pthread_cleanup_pop(execute);
+.EE
+.in
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the names.
+.SH HISTORY
+glibc 2.0
+.SH SEE ALSO
+.BR pthread_cancel (3),
+.BR pthread_cleanup_push (3),
+.BR pthread_setcancelstate (3),
+.BR pthread_testcancel (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_cond_broadcast.3 b/man/man3/pthread_cond_broadcast.3
new file mode 100644
index 000000000..0fe85adc1
--- /dev/null
+++ b/man/man3/pthread_cond_broadcast.3
@@ -0,0 +1 @@
+.so man3/pthread_cond_init.3
diff --git a/man/man3/pthread_cond_destroy.3 b/man/man3/pthread_cond_destroy.3
new file mode 100644
index 000000000..0fe85adc1
--- /dev/null
+++ b/man/man3/pthread_cond_destroy.3
@@ -0,0 +1 @@
+.so man3/pthread_cond_init.3
diff --git a/man/man3/pthread_cond_init.3 b/man/man3/pthread_cond_init.3
new file mode 100644
index 000000000..8472d2eb5
--- /dev/null
+++ b/man/man3/pthread_cond_init.3
@@ -0,0 +1,264 @@
+.\" Copyright, Xavier Leroy <Xavier.Leroy@inria.fr>
+.\" Copyright 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_cond_init 3 (date) "Linux man-pages (unreleased)"
+.
+.
+.SH NAME
+pthread_cond_init,
+pthread_cond_signal,
+pthread_cond_broadcast,
+pthread_cond_wait,
+pthread_cond_timedwait,
+pthread_cond_destroy
+\-
+operations on conditions
+.
+.
+.SH SYNOPSIS
+.B #include <pthread.h>
+.P
+.BI "pthread_cond_t " cond " = PTHREAD_COND_INITIALIZER;"
+.P
+.BI "int pthread_cond_init(pthread_cond_t *" cond ", pthread_condattr_t *" cond_attr ");"
+.BI "int pthread_cond_signal(pthread_cond_t *" cond ");"
+.BI "int pthread_cond_broadcast(pthread_cond_t *" cond ");"
+.BI "int pthread_cond_wait(pthread_cond_t *" cond ", pthread_mutex_t *" mutex ");"
+.BI "int pthread_cond_timedwait(pthread_cond_t *" cond ", pthread_mutex_t *" mutex ", const struct timespec *" abstime ");"
+.BI "int pthread_cond_destroy(pthread_cond_t *" cond ");"
+.
+.
+.SH DESCRIPTION
+A condition (short for ``condition variable'')
+is a synchronization device that allows threads
+to suspend execution and relinquish the processors
+until some predicate on shared data is satisfied.
+The basic operations on conditions are:
+signal the condition (when the predicate becomes true),
+and wait for the condition,
+suspending the thread execution until another thread signals the condition.
+.P
+A condition variable must always be associated with a mutex,
+to avoid the race condition where
+a thread prepares to wait on a condition variable
+and another thread signals the condition
+just before the first thread actually waits on it.
+.P
+\fBpthread_cond_init\fP initializes the condition variable \fIcond\fP,
+using the condition attributes specified in \fIcond_attr\fP,
+or default attributes if \fIcond_attr\fP is \fBNULL\fP.
+The LinuxThreads implementation supports no attributes for conditions,
+hence the \fIcond_attr\fP parameter is actually ignored.
+.P
+Variables of type \fBpthread_cond_t\fP can also be initialized statically,
+using the constant \fBPTHREAD_COND_INITIALIZER\fP.
+.P
+\fBpthread_cond_signal\fP restarts one of the threads that
+are waiting on the condition variable \fIcond\fP.
+If no threads are waiting on \fIcond\fP,
+nothing happens.
+If several threads are waiting on \fIcond\fP,
+exactly one is restarted,
+but it is not specified which.
+.P
+\fBpthread_cond_broadcast\fP restarts all the threads that
+are waiting on the condition variable \fIcond\fP.
+Nothing happens if no threads are waiting on \fIcond\fP.
+.P
+\fBpthread_cond_wait\fP atomically unlocks the \fImutex\fP
+(as per \fBpthread_unlock_mutex\fP)
+and waits for the condition variable \fIcond\fP to be signaled.
+The thread execution is suspended and does not consume any CPU time
+until the condition variable is signaled.
+The \fImutex\fP must be locked by the calling thread
+on entrance to \fBpthread_cond_wait\fP.
+Before returning to the calling thread,
+\fBpthread_cond_wait\fP re-acquires \fImutex\fP
+(as per \fBpthread_lock_mutex\fP).
+.P
+Unlocking the mutex and suspending on the condition variable is done atomically.
+Thus,
+if all threads always acquire the mutex before signaling the condition,
+this guarantees that the condition cannot be signaled (and thus ignored)
+between the time a thread locks the mutex
+and the time it waits on the condition variable.
+.P
+\fBpthread_cond_timedwait\fP atomically unlocks \fImutex\fP
+and waits on \fIcond\fP,
+as \fBpthread_cond_wait\fP does,
+but it also bounds the duration of the wait.
+If \fIcond\fP has not been signaled
+within the amount of time specified by \fIabstime\fP,
+the mutex \fImutex\fP is re-acquired
+and \fBpthread_cond_timedwait\fP returns the error \fBETIMEDOUT\fP.
+The \fIabstime\fP parameter specifies an absolute time,
+with the same origin as \fBtime\fP(2) and \fBgettimeofday\fP(2):
+an \fIabstime\fP of 0
+corresponds to 00:00:00 GMT, January 1, 1970.
+.P
+\fBpthread_cond_destroy\fP destroys a condition variable,
+freeing the resources it might hold.
+No threads must be waiting on the condition variable
+on entrance to \fBpthread_cond_destroy\fP.
+In the LinuxThreads implementation,
+no resources are associated with condition variables,
+thus \fBpthread_cond_destroy\fP actually does nothing
+except checking that the condition has no waiting threads.
+.
+.
+.SH CANCELLATION
+\fBpthread_cond_wait\fP and \fBpthread_cond_timedwait\fP
+are cancelation points.
+If a thread is cancelled while suspended in one of these functions,
+the thread immediately resumes execution,
+then locks again the \fImutex\fP
+argument to \fBpthread_cond_wait\fP and \fBpthread_cond_timedwait\fP,
+and finally executes the cancelation.
+Consequently,
+cleanup handlers are assured that \fImutex\fP is locked
+when they are called.
+.
+.
+.SH "ASYNC-SIGNAL SAFETY"
+The condition functions are not async-signal safe,
+and should not be called from a signal handler.
+In particular,
+calling \fBpthread_cond_signal\fP or \fBpthread_cond_broadcast\fP
+from a signal handler
+may deadlock the calling thread.
+.
+.
+.SH "RETURN VALUE"
+All condition variable functions return 0 on success
+and a non-zero error code on error.
+.
+.
+.SH ERRORS
+\fBpthread_cond_init\fP,
+\fBpthread_cond_signal\fP,
+\fBpthread_cond_broadcast\fP,
+and \fBpthread_cond_wait\fP
+never return an error code.
+.P
+The \fBpthread_cond_timedwait\fP function returns
+the following error codes on error:
+.RS
+.TP
+\fBETIMEDOUT\fP
+The condition variable was not signaled
+until the timeout specified by \fIabstime\fP.
+.TP
+\fBEINTR\fP
+\fBpthread_cond_timedwait\fP was interrupted by a signal.
+.RE
+.P
+The \fBpthread_cond_destroy\fP function returns
+the following error code on error:
+.RS
+.TP
+\fBEBUSY\fP
+Some threads are currently waiting on \fIcond\fP.
+.RE
+.
+.
+.SH "SEE ALSO"
+\fBpthread_condattr_init\fP(3),
+\fBpthread_mutex_lock\fP(3),
+\fBpthread_mutex_unlock\fP(3),
+\fBgettimeofday\fP(2),
+\fBnanosleep\fP(2).
+.
+.
+.SH EXAMPLE
+Consider two shared variables \fIx\fP and \fIy\fP,
+protected by the mutex \fImut\fP,
+and a condition variable \fIcond\fP
+that is to be signaled
+whenever \fIx\fP becomes greater than \fIy\fP.
+.P
+.RS
+.ft 3
+.nf
+.sp
+int x,y;
+pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+.ft
+.P
+.RE
+.fi
+.P
+Waiting until \fIx\fP is greater than \fIy\fP is performed as follows:
+.P
+.RS
+.ft 3
+.nf
+.sp
+pthread_mutex_lock(&mut);
+while (x <= y) {
+        pthread_cond_wait(&cond, &mut);
+}
+/* operate on x and y */
+pthread_mutex_unlock(&mut);
+.ft
+.P
+.RE
+.fi
+.P
+Modifications on \fIx\fP and \fIy\fP
+that may cause \fIx\fP to become greater than \fIy\fP
+should signal the condition if needed:
+.P
+.RS
+.ft 3
+.nf
+.sp
+pthread_mutex_lock(&mut);
+/* modify x and y */
+if (x > y) pthread_cond_broadcast(&cond);
+pthread_mutex_unlock(&mut);
+.ft
+.P
+.RE
+.fi
+.P
+If it can be proved that at most one waiting thread needs to be waken up
+(for instance,
+if there are only two threads communicating through \fIx\fP and \fIy\fP),
+\fBpthread_cond_signal\fP can be used as
+a slightly more efficient alternative to \fBpthread_cond_broadcast\fP.
+In doubt,
+use \fBpthread_cond_broadcast\fP.
+.P
+To wait for \fIx\fP to become greater than \fIy\fP
+with a timeout of 5 seconds,
+do:
+.P
+.RS
+.ft 3
+.nf
+.sp
+struct timeval now;
+struct timespec timeout;
+int retcode;
+\&
+pthread_mutex_lock(&mut);
+gettimeofday(&now);
+timeout.tv_sec = now.tv_sec + 5;
+timeout.tv_nsec = now.tv_usec * 1000;
+retcode = 0;
+while (x <= y && retcode != ETIMEDOUT) {
+        retcode = pthread_cond_timedwait(&cond, &mut, &timeout);
+}
+if (retcode == ETIMEDOUT) {
+        /* timeout occurred */
+} else {
+        /* operate on x and y */
+}
+pthread_mutex_unlock(&mut);
+.ft
+.P
+.RE
+.fi
diff --git a/man/man3/pthread_cond_signal.3 b/man/man3/pthread_cond_signal.3
new file mode 100644
index 000000000..0fe85adc1
--- /dev/null
+++ b/man/man3/pthread_cond_signal.3
@@ -0,0 +1 @@
+.so man3/pthread_cond_init.3
diff --git a/man/man3/pthread_cond_timedwait.3 b/man/man3/pthread_cond_timedwait.3
new file mode 100644
index 000000000..0fe85adc1
--- /dev/null
+++ b/man/man3/pthread_cond_timedwait.3
@@ -0,0 +1 @@
+.so man3/pthread_cond_init.3
diff --git a/man/man3/pthread_cond_wait.3 b/man/man3/pthread_cond_wait.3
new file mode 100644
index 000000000..0fe85adc1
--- /dev/null
+++ b/man/man3/pthread_cond_wait.3
@@ -0,0 +1 @@
+.so man3/pthread_cond_init.3
diff --git a/man/man3/pthread_condattr_destroy.3 b/man/man3/pthread_condattr_destroy.3
new file mode 100644
index 000000000..ae5c63cd9
--- /dev/null
+++ b/man/man3/pthread_condattr_destroy.3
@@ -0,0 +1 @@
+.so man3/pthread_condattr_init.3
diff --git a/man/man3/pthread_condattr_init.3 b/man/man3/pthread_condattr_init.3
new file mode 100644
index 000000000..0f7c60d4d
--- /dev/null
+++ b/man/man3/pthread_condattr_init.3
@@ -0,0 +1,48 @@
+.\" Copyright, Xavier Leroy <Xavier.Leroy@inria.fr>
+.\" Copyright 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_condattr_init 3 (date) "Linux man-pages (unreleased)"
+.
+.
+.SH NAME
+pthread_condattr_init,
+pthread_condattr_destroy
+\-
+condition creation attributes
+.
+.
+.SH SYNOPSIS
+.B #include <pthread.h>
+.P
+.BI "int pthread_condattr_init(pthread_condattr_t *" attr ");"
+.BI "int pthread_condattr_destroy(pthread_condattr_t *" attr ");"
+.
+.
+.SH DESCRIPTION
+Condition attributes can be specified at condition creation time,
+by passing a condition attribute object
+as second argument to \fBpthread_cond_init\fP(3).
+Passing \fBNULL\fP is equivalent to
+passing a condition attribute object
+with all attributes set to their default values.
+.P
+The LinuxThreads implementation supports no attributes for conditions.
+The functions on condition attributes are
+included only for compliance with the POSIX standard.
+.P
+\fBpthread_condattr_init\fP
+initializes the condition attribute object \fIattr\fP
+and fills it with default values for the attributes.
+\fBpthread_condattr_destroy\fP destroys a condition attribute object,
+which must not be reused until it is reinitialized.
+Both functions do nothing in the LinuxThreads implementation.
+.
+.
+.SH "RETURN VALUE"
+\fBpthread_condattr_init\fP and \fBpthread_condattr_destroy\fP always return 0.
+.
+.
+.SH "SEE ALSO"
+\fBpthread_cond_init\fP(3).
diff --git a/man/man3/pthread_create.3 b/man/man3/pthread_create.3
new file mode 100644
index 000000000..fd6253bf4
--- /dev/null
+++ b/man/man3/pthread_create.3
@@ -0,0 +1,394 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_create 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_create \- create a new thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_create(pthread_t *restrict " thread ,
+.BI "                   const pthread_attr_t *restrict " attr ,
+.BI "                   void *(*" start_routine ")(void *),"
+.BI "                   void *restrict " arg );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_create ()
+function starts a new thread in the calling process.
+The new thread starts execution by invoking
+.IR start_routine ();
+.I arg
+is passed as the sole argument of
+.IR start_routine ().
+.P
+The new thread terminates in one of the following ways:
+.IP \[bu] 3
+It calls
+.BR pthread_exit (3),
+specifying an exit status value that is available to another thread
+in the same process that calls
+.BR pthread_join (3).
+.IP \[bu]
+It returns from
+.IR start_routine ().
+This is equivalent to calling
+.BR pthread_exit (3)
+with the value supplied in the
+.I return
+statement.
+.IP \[bu]
+It is canceled (see
+.BR pthread_cancel (3)).
+.IP \[bu]
+Any of the threads in the process calls
+.BR exit (3),
+or the main thread performs a return from
+.IR main ().
+This causes the termination of all threads in the process.
+.P
+The
+.I attr
+argument points to a
+.I pthread_attr_t
+structure whose contents are used at thread creation time to
+determine attributes for the new thread;
+this structure is initialized using
+.BR pthread_attr_init (3)
+and related functions.
+If
+.I attr
+is NULL,
+then the thread is created with default attributes.
+.P
+Before returning, a successful call to
+.BR pthread_create ()
+stores the ID of the new thread in the buffer pointed to by
+.IR thread ;
+this identifier is used to refer to the thread
+in subsequent calls to other pthreads functions.
+.P
+The new thread inherits a copy of the creating thread's signal mask
+.RB ( pthread_sigmask (3)).
+The set of pending signals for the new thread is empty
+.RB ( sigpending (2)).
+The new thread does not inherit the creating thread's
+alternate signal stack
+.RB ( sigaltstack (2)).
+.P
+The new thread inherits the calling thread's floating-point environment
+.RB ( fenv (3)).
+.P
+The initial value of the new thread's CPU-time clock is 0
+(see
+.BR pthread_getcpuclockid (3)).
+.\" CLOCK_THREAD_CPUTIME_ID in clock_gettime(2)
+.SS Linux-specific details
+The new thread inherits copies of the calling thread's capability sets
+(see
+.BR capabilities (7))
+and CPU affinity mask (see
+.BR sched_setaffinity (2)).
+.SH RETURN VALUE
+On success,
+.BR pthread_create ()
+returns 0;
+on error, it returns an error number, and the contents of
+.I *thread
+are undefined.
+.SH ERRORS
+.TP
+.B EAGAIN
+Insufficient resources to create another thread.
+.TP
+.B EAGAIN
+.\" NOTE! The following should match the description in fork(2)
+A system-imposed limit on the number of threads was encountered.
+There are a number of limits that may trigger this error: the
+.B RLIMIT_NPROC
+soft resource limit (set via
+.BR setrlimit (2)),
+which limits the number of processes and threads for a real user ID,
+was reached;
+the kernel's system-wide limit on the number of processes and threads,
+.IR /proc/sys/kernel/threads\-max ,
+was reached (see
+.BR proc (5));
+or the maximum number of PIDs,
+.IR /proc/sys/kernel/pid_max ,
+was reached (see
+.BR proc (5)).
+.TP
+.B EINVAL
+Invalid settings in
+.IR attr .
+.TP
+.\" FIXME . Test the following
+.B EPERM
+No permission to set the scheduling policy and parameters specified in
+.IR attr .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_create ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+See
+.BR pthread_self (3)
+for further information on the thread ID returned in
+.I *thread
+by
+.BR pthread_create ().
+Unless real-time scheduling policies are being employed,
+after a call to
+.BR pthread_create (),
+it is indeterminate which thread\[em]the caller or the new thread\[em]will
+next execute.
+.P
+A thread may either be
+.I joinable
+or
+.IR detached .
+If a thread is joinable, then another thread can call
+.BR pthread_join (3)
+to wait for the thread to terminate and fetch its exit status.
+Only when a terminated joinable thread has been joined are
+the last of its resources released back to the system.
+When a detached thread terminates,
+its resources are automatically released back to the system:
+it is not possible to join with the thread in order to obtain
+its exit status.
+Making a thread detached is useful for some types of daemon threads
+whose exit status the application does not need to care about.
+By default, a new thread is created in a joinable state, unless
+.I attr
+was set to create the thread in a detached state (using
+.BR pthread_attr_setdetachstate (3)).
+.P
+Under the NPTL threading implementation, if the
+.B RLIMIT_STACK
+soft resource limit
+.I at the time the program started
+has any value other than "unlimited",
+then it determines the default stack size of new threads.
+Using
+.BR pthread_attr_setstacksize (3),
+the stack size attribute can be explicitly set in the
+.I attr
+argument used to create a thread,
+in order to obtain a stack size other than the default.
+If the
+.B RLIMIT_STACK
+resource limit is set to "unlimited",
+a per-architecture value is used for the stack size:
+2 MB on most architectures; 4 MB on POWER and Sparc-64.
+.SH BUGS
+In the obsolete LinuxThreads implementation,
+each of the threads in a process has a different process ID.
+This is in violation of the POSIX threads specification,
+and is the source of many other nonconformances to the standard; see
+.BR pthreads (7).
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR pthread_create (),
+as well as a number of other functions in the pthreads API.
+.P
+In the following run,
+on a system providing the NPTL threading implementation,
+the stack size defaults to the value given by the
+"stack size" resource limit:
+.P
+.in +4n
+.EX
+.RB "$" " ulimit \-s"
+8192            # The stack size limit is 8 MB (0x800000 bytes)
+.RB "$" " ./a.out hola salut servus"
+Thread 1: top of stack near 0xb7dd03b8; argv_string=hola
+Thread 2: top of stack near 0xb75cf3b8; argv_string=salut
+Thread 3: top of stack near 0xb6dce3b8; argv_string=servus
+Joined with thread 1; returned value was HOLA
+Joined with thread 2; returned value was SALUT
+Joined with thread 3; returned value was SERVUS
+.EE
+.in
+.P
+In the next run, the program explicitly sets a stack size of 1\ MB (using
+.BR pthread_attr_setstacksize (3))
+for the created threads:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \-s 0x100000 hola salut servus"
+Thread 1: top of stack near 0xb7d723b8; argv_string=hola
+Thread 2: top of stack near 0xb7c713b8; argv_string=salut
+Thread 3: top of stack near 0xb7b703b8; argv_string=servus
+Joined with thread 1; returned value was HOLA
+Joined with thread 2; returned value was SALUT
+Joined with thread 3; returned value was SERVUS
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_create.c)
+.EX
+#include <ctype.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+#define handle_error(msg) \e
+        do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+struct thread_info {    /* Used as argument to thread_start() */
+    pthread_t thread_id;        /* ID returned by pthread_create() */
+    int       thread_num;       /* Application\-defined thread # */
+    char     *argv_string;      /* From command\-line argument */
+};
+\&
+/* Thread start function: display address near top of our stack,
+   and return upper\-cased copy of argv_string. */
+\&
+static void *
+thread_start(void *arg)
+{
+    struct thread_info *tinfo = arg;
+    char *uargv;
+\&
+    printf("Thread %d: top of stack near %p; argv_string=%s\en",
+           tinfo\->thread_num, (void *) &tinfo, tinfo\->argv_string);
+\&
+    uargv = strdup(tinfo\->argv_string);
+    if (uargv == NULL)
+        handle_error("strdup");
+\&
+    for (char *p = uargv; *p != \[aq]\e0\[aq]; p++)
+        *p = toupper(*p);
+\&
+    return uargv;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int                 s, opt;
+    void                *res;
+    size_t              num_threads;
+    ssize_t             stack_size;
+    pthread_attr_t      attr;
+    struct thread_info  *tinfo;
+\&
+    /* The "\-s" option specifies a stack size for our threads. */
+\&
+    stack_size = \-1;
+    while ((opt = getopt(argc, argv, "s:")) != \-1) {
+        switch (opt) {
+        case \[aq]s\[aq]:
+            stack_size = strtoul(optarg, NULL, 0);
+            break;
+\&
+        default:
+            fprintf(stderr, "Usage: %s [\-s stack\-size] arg...\en",
+                    argv[0]);
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    num_threads = argc \- optind;
+\&
+    /* Initialize thread creation attributes. */
+\&
+    s = pthread_attr_init(&attr);
+    if (s != 0)
+        handle_error_en(s, "pthread_attr_init");
+\&
+    if (stack_size > 0) {
+        s = pthread_attr_setstacksize(&attr, stack_size);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_setstacksize");
+    }
+\&
+    /* Allocate memory for pthread_create() arguments. */
+\&
+    tinfo = calloc(num_threads, sizeof(*tinfo));
+    if (tinfo == NULL)
+        handle_error("calloc");
+\&
+    /* Create one thread for each command\-line argument. */
+\&
+    for (size_t tnum = 0; tnum < num_threads; tnum++) {
+        tinfo[tnum].thread_num = tnum + 1;
+        tinfo[tnum].argv_string = argv[optind + tnum];
+\&
+        /* The pthread_create() call stores the thread ID into
+           corresponding element of tinfo[]. */
+\&
+        s = pthread_create(&tinfo[tnum].thread_id, &attr,
+                           &thread_start, &tinfo[tnum]);
+        if (s != 0)
+            handle_error_en(s, "pthread_create");
+    }
+\&
+    /* Destroy the thread attributes object, since it is no
+       longer needed. */
+\&
+    s = pthread_attr_destroy(&attr);
+    if (s != 0)
+        handle_error_en(s, "pthread_attr_destroy");
+\&
+    /* Now join with each thread, and display its returned value. */
+\&
+    for (size_t tnum = 0; tnum < num_threads; tnum++) {
+        s = pthread_join(tinfo[tnum].thread_id, &res);
+        if (s != 0)
+            handle_error_en(s, "pthread_join");
+\&
+        printf("Joined with thread %d; returned value was %s\en",
+               tinfo[tnum].thread_num, (char *) res);
+        free(res);      /* Free memory allocated by thread */
+    }
+\&
+    free(tinfo);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR getrlimit (2),
+.BR pthread_attr_init (3),
+.BR pthread_cancel (3),
+.BR pthread_detach (3),
+.BR pthread_equal (3),
+.BR pthread_exit (3),
+.BR pthread_getattr_np (3),
+.BR pthread_join (3),
+.BR pthread_self (3),
+.BR pthread_setattr_default_np (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_detach.3 b/man/man3/pthread_detach.3
new file mode 100644
index 000000000..d8b02ed86
--- /dev/null
+++ b/man/man3/pthread_detach.3
@@ -0,0 +1,105 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_detach 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_detach \- detach a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_detach(pthread_t " thread );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_detach ()
+function marks the thread identified by
+.I thread
+as detached.
+When a detached thread terminates,
+its resources are automatically released back to the system without
+the need for another thread to join with the terminated thread.
+.P
+Attempting to detach an already detached thread results
+in unspecified behavior.
+.SH RETURN VALUE
+On success,
+.BR pthread_detach ()
+returns 0;
+on error, it returns an error number.
+.SH ERRORS
+.TP
+.B EINVAL
+.I thread
+is not a joinable thread.
+.TP
+.B ESRCH
+No thread with the ID
+.I thread
+could be found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_detach ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+Once a thread has been detached, it can't be joined with
+.BR pthread_join (3)
+or be made joinable again.
+.P
+A new thread can be created in a detached state using
+.BR pthread_attr_setdetachstate (3)
+to set the detached attribute of the
+.I attr
+argument of
+.BR pthread_create (3).
+.P
+The detached attribute merely determines the behavior of the system
+when the thread terminates;
+it does not prevent the thread from being terminated
+if the process terminates using
+.BR exit (3)
+(or equivalently, if the main thread returns).
+.P
+Either
+.BR pthread_join (3)
+or
+.BR pthread_detach ()
+should be called for each thread that an application creates,
+so that system resources for the thread can be released.
+(But note that the resources of any threads for which one of these
+actions has not been done will be freed when the process terminates.)
+.SH EXAMPLES
+The following statement detaches the calling thread:
+.P
+.in +4n
+.EX
+pthread_detach(pthread_self());
+.EE
+.in
+.SH SEE ALSO
+.BR pthread_attr_setdetachstate (3),
+.BR pthread_cancel (3),
+.BR pthread_create (3),
+.BR pthread_exit (3),
+.BR pthread_join (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_equal.3 b/man/man3/pthread_equal.3
new file mode 100644
index 000000000..214f3b6ba
--- /dev/null
+++ b/man/man3/pthread_equal.3
@@ -0,0 +1,57 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_equal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_equal \- compare thread IDs
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_equal(pthread_t " t1 ", pthread_t " t2 );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_equal ()
+function compares two thread identifiers.
+.SH RETURN VALUE
+If the two thread IDs are equal,
+.BR pthread_equal ()
+returns a nonzero value; otherwise, it returns 0.
+.SH ERRORS
+This function always succeeds.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_equal ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The
+.BR pthread_equal ()
+function is necessary because thread IDs should be considered opaque:
+there is no portable way for applications to directly compare two
+.I pthread_t
+values.
+.SH SEE ALSO
+.BR pthread_create (3),
+.BR pthread_self (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_exit.3 b/man/man3/pthread_exit.3
new file mode 100644
index 000000000..dc1de8c19
--- /dev/null
+++ b/man/man3/pthread_exit.3
@@ -0,0 +1,106 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_exit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_exit \- terminate calling thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "[[noreturn]] void pthread_exit(void *" retval );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_exit ()
+function terminates the calling thread and returns a value via
+.I retval
+that (if the thread is joinable)
+is available to another thread in the same process that calls
+.BR pthread_join (3).
+.P
+Any clean-up handlers established by
+.BR pthread_cleanup_push (3)
+that have not yet been popped,
+are popped (in the reverse of the order in which they were pushed)
+and executed.
+If the thread has any thread-specific data, then,
+after the clean-up handlers have been executed,
+the corresponding destructor functions are called,
+in an unspecified order.
+.P
+When a thread terminates,
+process-shared resources (e.g., mutexes, condition variables,
+semaphores, and file descriptors) are not released,
+and functions registered using
+.BR atexit (3)
+are not called.
+.P
+After the last thread in a process terminates,
+the process terminates as by calling
+.BR exit (3)
+with an exit status of zero;
+thus, process-shared resources
+are released and functions registered using
+.BR atexit (3)
+are called.
+.SH RETURN VALUE
+This function does not return to the caller.
+.SH ERRORS
+This function always succeeds.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_exit ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+Performing a return from the start function of any thread other
+than the main thread results in an implicit call to
+.BR pthread_exit (),
+using the function's return value as the thread's exit status.
+.P
+To allow other threads to continue execution,
+the main thread should terminate by calling
+.BR pthread_exit ()
+rather than
+.BR exit (3).
+.P
+The value pointed to by
+.I retval
+should not be located on the calling thread's stack,
+since the contents of that stack are undefined after the thread terminates.
+.SH BUGS
+Currently,
+.\" Linux 2.6.27
+there are limitations in the kernel implementation logic for
+.BR wait (2)ing
+on a stopped thread group with a dead thread group leader.
+This can manifest in problems such as a locked terminal if a stop signal is
+sent to a foreground process whose thread group leader has already called
+.BR pthread_exit ().
+.\" FIXME . review a later kernel to see if this gets fixed
+.\" http://thread.gmane.org/gmane.linux.kernel/611611
+.\" http://marc.info/?l=linux-kernel&m=122525468300823&w=2
+.SH SEE ALSO
+.BR pthread_create (3),
+.BR pthread_join (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_getaffinity_np.3 b/man/man3/pthread_getaffinity_np.3
new file mode 100644
index 000000000..c4cd6af78
--- /dev/null
+++ b/man/man3/pthread_getaffinity_np.3
@@ -0,0 +1 @@
+.so man3/pthread_setaffinity_np.3
diff --git a/man/man3/pthread_getattr_default_np.3 b/man/man3/pthread_getattr_default_np.3
new file mode 100644
index 000000000..97f734eb9
--- /dev/null
+++ b/man/man3/pthread_getattr_default_np.3
@@ -0,0 +1,192 @@
+'\" t
+.\" Copyright (c) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_getattr_default_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_getattr_default_np, pthread_setattr_default_np, \-
+get or set default thread-creation attributes
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.BI "int pthread_getattr_default_np(pthread_attr_t *" attr );
+.BI "int pthread_setattr_default_np(const pthread_attr_t *" attr );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_setattr_default_np ()
+function sets the default attributes used for creation of a new
+thread\[em]that is, the attributes that are used when
+.BR pthread_create (3)
+is called with a second argument that is NULL.
+The default attributes are set using the attributes supplied in
+.IR *attr ,
+a previously initialized thread attributes object.
+Note the following details about the supplied attributes object:
+.IP \[bu] 3
+The attribute settings in the object must be valid.
+.IP \[bu]
+The
+.I stack address
+attribute must not be set in the object.
+.IP \[bu]
+Setting the
+.I stack size
+attribute to zero means leave the default stack size unchanged.
+.P
+The
+.BR pthread_getattr_default_np ()
+function initializes the thread attributes object referred to by
+.I attr
+so that it contains the default attributes used for thread creation.
+.SH ERRORS
+.TP
+.B EINVAL
+.RB ( pthread_setattr_default_np ())
+One of the attribute settings in
+.I attr
+is invalid, or the stack address attribute is set in
+.IR attr .
+.TP
+.B ENOMEM
+.\" Can happen (but unlikely) while trying to allocate memory for cpuset
+.RB ( pthread_setattr_default_np ())
+Insufficient memory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_getattr_default_np (),
+.BR pthread_setattr_default_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in their names.
+.SH HISTORY
+glibc 2.18.
+.SH EXAMPLES
+The program below uses
+.BR pthread_getattr_default_np ()
+to fetch the default thread-creation attributes and then displays
+various settings from the returned thread attributes object.
+When running the program, we see the following output:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+Stack size:          8388608
+Guard size:          4096
+Scheduling policy:   SCHED_OTHER
+Scheduling priority: 0
+Detach state:        JOINABLE
+Inherit scheduler:   INHERIT
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_getattr_default_np.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+static void
+display_pthread_attr(pthread_attr_t *attr)
+{
+    int s;
+    size_t stacksize;
+    size_t guardsize;
+    int policy;
+    struct sched_param schedparam;
+    int detachstate;
+    int inheritsched;
+\&
+    s = pthread_attr_getstacksize(attr, &stacksize);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getstacksize");
+    printf("Stack size:          %zu\en", stacksize);
+\&
+    s = pthread_attr_getguardsize(attr, &guardsize);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getguardsize");
+    printf("Guard size:          %zu\en", guardsize);
+\&
+    s = pthread_attr_getschedpolicy(attr, &policy);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getschedpolicy");
+    printf("Scheduling policy:   %s\en",
+           (policy == SCHED_FIFO) ? "SCHED_FIFO" :
+           (policy == SCHED_RR) ? "SCHED_RR" :
+           (policy == SCHED_OTHER) ? "SCHED_OTHER" : "[unknown]");
+\&
+    s = pthread_attr_getschedparam(attr, &schedparam);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getschedparam");
+    printf("Scheduling priority: %d\en", schedparam.sched_priority);
+\&
+    s = pthread_attr_getdetachstate(attr, &detachstate);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getdetachstate");
+    printf("Detach state:        %s\en",
+           (detachstate == PTHREAD_CREATE_DETACHED) ? "DETACHED" :
+           (detachstate == PTHREAD_CREATE_JOINABLE) ? "JOINABLE" :
+           "???");
+\&
+    s = pthread_attr_getinheritsched(attr, &inheritsched);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getinheritsched");
+    printf("Inherit scheduler:   %s\en",
+           (inheritsched == PTHREAD_INHERIT_SCHED) ? "INHERIT" :
+           (inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
+           "???");
+}
+\&
+int
+main(void)
+{
+    int s;
+    pthread_attr_t attr;
+\&
+    s = pthread_getattr_default_np(&attr);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_getattr_default_np");
+\&
+    display_pthread_attr(&attr);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_attr_getaffinity_np (3),
+.BR pthread_attr_getdetachstate (3),
+.BR pthread_attr_getguardsize (3),
+.BR pthread_attr_getinheritsched (3),
+.BR pthread_attr_getschedparam (3),
+.BR pthread_attr_getschedpolicy (3),
+.BR pthread_attr_getscope (3),
+.BR pthread_attr_getstack (3),
+.BR pthread_attr_getstackaddr (3),
+.BR pthread_attr_getstacksize (3),
+.BR pthread_attr_init (3),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_getattr_np.3 b/man/man3/pthread_getattr_np.3
new file mode 100644
index 000000000..2c9d7c196
--- /dev/null
+++ b/man/man3/pthread_getattr_np.3
@@ -0,0 +1,356 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_getattr_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_getattr_np \- get attributes of created thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.BI "int pthread_getattr_np(pthread_t " thread ", pthread_attr_t *" attr );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_getattr_np ()
+function initializes the thread attributes object referred to by
+.I attr
+so that it contains actual attribute values describing the running thread
+.IR thread .
+.P
+The returned attribute values may differ from
+the corresponding attribute values passed in the
+.I attr
+object that was used to create the thread using
+.BR pthread_create (3).
+In particular, the following attributes may differ:
+.IP \[bu] 3
+the detach state, since a joinable thread may have detached itself
+after creation;
+.IP \[bu]
+the stack size,
+which the implementation may align to a suitable boundary.
+.IP \[bu]
+and the guard size,
+which the implementation may round upward to a multiple of the page size,
+or ignore (i.e., treat as 0),
+if the application is allocating its own stack.
+.P
+Furthermore, if the stack address attribute was not set
+in the thread attributes object used to create the thread,
+then the returned thread attributes object will report the actual
+stack address that the implementation selected for the thread.
+.P
+When the thread attributes object returned by
+.BR pthread_getattr_np ()
+is no longer required, it should be destroyed using
+.BR pthread_attr_destroy (3).
+.SH RETURN VALUE
+On success, this function returns 0;
+on error, it returns a nonzero error number.
+.SH ERRORS
+.TP
+.B ENOMEM
+.\" Can happen (but unlikely) while trying to allocate memory for cpuset
+Insufficient memory.
+.P
+In addition, if
+.I thread
+refers to the main thread, then
+.BR pthread_getattr_np ()
+can fail because of errors from various underlying calls:
+.BR fopen (3),
+if
+.I /proc/self/maps
+can't be opened;
+and
+.BR getrlimit (2),
+if the
+.B RLIMIT_STACK
+resource limit is not supported.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_getattr_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the name.
+.SH HISTORY
+glibc 2.2.3.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR pthread_getattr_np ().
+The program creates a thread that then uses
+.BR pthread_getattr_np ()
+to retrieve and display its guard size, stack address,
+and stack size attributes.
+Command-line arguments can be used to set these attributes
+to values other than the default when creating the thread.
+The shell sessions below demonstrate the use of the program.
+.P
+In the first run, on an x86-32 system,
+a thread is created using default attributes:
+.P
+.in +4n
+.EX
+.RB "$" " ulimit \-s" "      # No stack limit ==> default stack size is 2 MB"
+unlimited
+.RB "$" " ./a.out"
+Attributes of created thread:
+        Guard size          = 4096 bytes
+        Stack address       = 0x40196000 (EOS = 0x40397000)
+        Stack size          = 0x201000 (2101248) bytes
+.EE
+.in
+.P
+In the following run, we see that if a guard size is specified,
+it is rounded up to the next multiple of the system page size
+(4096 bytes on x86-32):
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \-g 4097"
+Thread attributes object after initializations:
+        Guard size          = 4097 bytes
+        Stack address       = (nil)
+        Stack size          = 0x0 (0) bytes
+\&
+Attributes of created thread:
+        Guard size          = 8192 bytes
+        Stack address       = 0x40196000 (EOS = 0x40397000)
+        Stack size          = 0x201000 (2101248) bytes
+.EE
+.in
+.\".in +4n
+.\".nf
+.\"$ ./a.out \-s 0x8000
+.\"Thread attributes object after initializations:
+.\"        Guard size          = 4096 bytes
+.\"        Stack address       = 0xffff8000 (EOS = (nil))
+.\"        Stack size          = 0x8000 (32768) bytes
+.\"
+.\"Attributes of created thread:
+.\"        Guard size          = 4096 bytes
+.\"        Stack address       = 0x4001e000 (EOS = 0x40026000)
+.\"        Stack size          = 0x8000 (32768) bytes
+.\".fi
+.\".in
+.P
+In the last run, the program manually allocates a stack for the thread.
+In this case, the guard size attribute is ignored.
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \-g 4096 \-s 0x8000 \-a"
+Allocated thread stack at 0x804d000
+\&
+Thread attributes object after initializations:
+        Guard size          = 4096 bytes
+        Stack address       = 0x804d000 (EOS = 0x8055000)
+        Stack size          = 0x8000 (32768) bytes
+\&
+Attributes of created thread:
+        Guard size          = 0 bytes
+        Stack address       = 0x804d000 (EOS = 0x8055000)
+        Stack size          = 0x8000 (32768) bytes
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_getattr_np.c)
+.EX
+#define _GNU_SOURCE     /* To get pthread_getattr_np() declaration */
+#include <err.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+static void
+display_stack_related_attributes(pthread_attr_t *attr, char *prefix)
+{
+    int s;
+    size_t stack_size, guard_size;
+    void *stack_addr;
+\&
+    s = pthread_attr_getguardsize(attr, &guard_size);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getguardsize");
+    printf("%sGuard size          = %zu bytes\en", prefix, guard_size);
+\&
+    s = pthread_attr_getstack(attr, &stack_addr, &stack_size);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_getstack");
+    printf("%sStack address       = %p", prefix, stack_addr);
+    if (stack_size > 0)
+        printf(" (EOS = %p)", (char *) stack_addr + stack_size);
+    printf("\en");
+    printf("%sStack size          = %#zx (%zu) bytes\en",
+           prefix, stack_size, stack_size);
+}
+\&
+static void
+display_thread_attributes(pthread_t thread, char *prefix)
+{
+    int s;
+    pthread_attr_t attr;
+\&
+    s = pthread_getattr_np(thread, &attr);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_getattr_np");
+\&
+    display_stack_related_attributes(&attr, prefix);
+\&
+    s = pthread_attr_destroy(&attr);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_attr_destroy");
+}
+\&
+static void *           /* Start function for thread we create */
+thread_start(void *arg)
+{
+    printf("Attributes of created thread:\en");
+    display_thread_attributes(pthread_self(), "\et");
+\&
+    exit(EXIT_SUCCESS);         /* Terminate all threads */
+}
+\&
+static void
+usage(char *pname, char *msg)
+{
+    if (msg != NULL)
+        fputs(msg, stderr);
+    fprintf(stderr, "Usage: %s [\-s stack\-size [\-a]]"
+            " [\-g guard\-size]\en", pname);
+    fprintf(stderr, "\et\et\-a means program should allocate stack\en");
+    exit(EXIT_FAILURE);
+}
+\&
+static pthread_attr_t *   /* Get thread attributes from command line */
+get_thread_attributes_from_cl(int argc, char *argv[],
+                              pthread_attr_t *attrp)
+{
+    int s, opt, allocate_stack;
+    size_t stack_size, guard_size;
+    void *stack_addr;
+    pthread_attr_t *ret_attrp = NULL;   /* Set to attrp if we initialize
+                                           a thread attributes object */
+    allocate_stack = 0;
+    stack_size = \-1;
+    guard_size = \-1;
+\&
+    while ((opt = getopt(argc, argv, "ag:s:")) != \-1) {
+        switch (opt) {
+        case \[aq]a\[aq]:   allocate_stack = 1;                     break;
+        case \[aq]g\[aq]:   guard_size = strtoul(optarg, NULL, 0);  break;
+        case \[aq]s\[aq]:   stack_size = strtoul(optarg, NULL, 0);  break;
+        default:    usage(argv[0], NULL);
+        }
+    }
+\&
+    if (allocate_stack && stack_size == \-1)
+        usage(argv[0], "Specifying \-a without \-s makes no sense\en");
+\&
+    if (argc > optind)
+        usage(argv[0], "Extraneous command\-line arguments\en");
+\&
+    if (stack_size != -1 || guard_size > 0) {
+        ret_attrp = attrp;
+\&
+        s = pthread_attr_init(attrp);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_init");
+    }
+\&
+    if (stack_size != -1) {
+        if (!allocate_stack) {
+            s = pthread_attr_setstacksize(attrp, stack_size);
+            if (s != 0)
+                errc(EXIT_FAILURE, s, "pthread_attr_setstacksize");
+        } else {
+            s = posix_memalign(&stack_addr, sysconf(_SC_PAGESIZE),
+                               stack_size);
+            if (s != 0)
+                errc(EXIT_FAILURE, s, "posix_memalign");
+            printf("Allocated thread stack at %p\en\en", stack_addr);
+\&
+            s = pthread_attr_setstack(attrp, stack_addr, stack_size);
+            if (s != 0)
+                errc(EXIT_FAILURE, s, "pthread_attr_setstacksize");
+        }
+    }
+\&
+    if (guard_size != -1) {
+        s = pthread_attr_setguardsize(attrp, guard_size);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_setstacksize");
+    }
+\&
+    return ret_attrp;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int s;
+    pthread_t thr;
+    pthread_attr_t attr;
+    pthread_attr_t *attrp = NULL;    /* Set to &attr if we initialize
+                                        a thread attributes object */
+\&
+    attrp = get_thread_attributes_from_cl(argc, argv, &attr);
+\&
+    if (attrp != NULL) {
+        printf("Thread attributes object after initializations:\en");
+        display_stack_related_attributes(attrp, "\et");
+        printf("\en");
+    }
+\&
+    s = pthread_create(&thr, attrp, &thread_start, NULL);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_create");
+\&
+    if (attrp != NULL) {
+        s = pthread_attr_destroy(attrp);
+        if (s != 0)
+            errc(EXIT_FAILURE, s, "pthread_attr_destroy");
+    }
+\&
+    pause();    /* Terminates when other thread calls exit() */
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_attr_getaffinity_np (3),
+.BR pthread_attr_getdetachstate (3),
+.BR pthread_attr_getguardsize (3),
+.BR pthread_attr_getinheritsched (3),
+.BR pthread_attr_getschedparam (3),
+.BR pthread_attr_getschedpolicy (3),
+.BR pthread_attr_getscope (3),
+.BR pthread_attr_getstack (3),
+.BR pthread_attr_getstackaddr (3),
+.BR pthread_attr_getstacksize (3),
+.BR pthread_attr_init (3),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_getconcurrency.3 b/man/man3/pthread_getconcurrency.3
new file mode 100644
index 000000000..8b2d54392
--- /dev/null
+++ b/man/man3/pthread_getconcurrency.3
@@ -0,0 +1 @@
+.so man3/pthread_setconcurrency.3
diff --git a/man/man3/pthread_getcpuclockid.3 b/man/man3/pthread_getcpuclockid.3
new file mode 100644
index 000000000..e352dfbce
--- /dev/null
+++ b/man/man3/pthread_getcpuclockid.3
@@ -0,0 +1,180 @@
+'\" t
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_getcpuclockid 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_getcpuclockid \- retrieve ID of a thread's CPU time clock
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.B #include <time.h>
+.P
+.BI "int pthread_getcpuclockid(pthread_t " thread ", clockid_t *" clockid );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_getcpuclockid ()
+function obtains the ID of the CPU-time clock of the thread whose ID is
+given in
+.IR thread ,
+and returns it in the location pointed to by
+.IR clockid .
+.\" The clockid is constructed as follows:
+.\" *clockid = CLOCK_THREAD_CPUTIME_ID | (pd->tid << CLOCK_IDFIELD_SIZE)
+.\" where CLOCK_IDFIELD_SIZE is 3.
+.SH RETURN VALUE
+On success, this function returns 0;
+on error, it returns a nonzero error number.
+.SH ERRORS
+.TP
+.B ENOENT
+.\" CLOCK_THREAD_CPUTIME_ID not defined
+Per-thread CPU time clocks are not supported by the system.
+.\"
+.\" Looking at nptl/pthread_getcpuclockid.c an ERANGE error would
+.\" be possible if kernel thread IDs took more than 29 bits (which
+.\" they currently cannot).
+.TP
+.B ESRCH
+No thread with the ID
+.I thread
+could be found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_getcpuclockid ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.SH NOTES
+When
+.I thread
+refers to the calling thread,
+this function returns an identifier that refers to the same clock
+manipulated by
+.BR clock_gettime (2)
+and
+.BR clock_settime (2)
+when given the clock ID
+.BR CLOCK_THREAD_CPUTIME_ID .
+.SH EXAMPLES
+The program below creates a thread and then uses
+.BR clock_gettime (2)
+to retrieve the total process CPU time,
+and the per-thread CPU time consumed by the two threads.
+The following shell session shows an example run:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+Main thread sleeping
+Subthread starting infinite loop
+Main thread consuming some CPU time...
+Process total CPU time:    1.368
+Main thread CPU time:      0.376
+Subthread CPU time:        0.992
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_getcpuclockid.c)
+.EX
+/* Link with "\-lrt" */
+\&
+#include <errno.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+\&
+#define handle_error(msg) \e
+        do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static void *
+thread_start(void *arg)
+{
+    printf("Subthread starting infinite loop\en");
+    for (;;)
+        continue;
+}
+\&
+static void
+pclock(char *msg, clockid_t cid)
+{
+    struct timespec ts;
+\&
+    printf("%s", msg);
+    if (clock_gettime(cid, &ts) == \-1)
+        handle_error("clock_gettime");
+    printf("%4jd.%03ld\en", (intmax_t) ts.tv_sec, ts.tv_nsec / 1000000);
+}
+\&
+int
+main(void)
+{
+    pthread_t thread;
+    clockid_t cid;
+    int s;
+\&
+    s = pthread_create(&thread, NULL, thread_start, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_create");
+\&
+    printf("Main thread sleeping\en");
+    sleep(1);
+\&
+    printf("Main thread consuming some CPU time...\en");
+    for (unsigned int j = 0; j < 2000000; j++)
+        getppid();
+\&
+    pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);
+\&
+    s = pthread_getcpuclockid(pthread_self(), &cid);
+    if (s != 0)
+        handle_error_en(s, "pthread_getcpuclockid");
+    pclock("Main thread CPU time:   ", cid);
+\&
+    /* The preceding 4 lines of code could have been replaced by:
+       pclock("Main thread CPU time:   ", CLOCK_THREAD_CPUTIME_ID); */
+\&
+    s = pthread_getcpuclockid(thread, &cid);
+    if (s != 0)
+        handle_error_en(s, "pthread_getcpuclockid");
+    pclock("Subthread CPU time: 1    ", cid);
+\&
+    exit(EXIT_SUCCESS);         /* Terminates both threads */
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR clock_settime (2),
+.BR timer_create (2),
+.BR clock_getcpuclockid (3),
+.BR pthread_self (3),
+.BR pthreads (7),
+.BR time (7)
diff --git a/man/man3/pthread_getname_np.3 b/man/man3/pthread_getname_np.3
new file mode 100644
index 000000000..a385c6e9e
--- /dev/null
+++ b/man/man3/pthread_getname_np.3
@@ -0,0 +1 @@
+.so man3/pthread_setname_np.3
diff --git a/man/man3/pthread_getschedparam.3 b/man/man3/pthread_getschedparam.3
new file mode 100644
index 000000000..67299c578
--- /dev/null
+++ b/man/man3/pthread_getschedparam.3
@@ -0,0 +1 @@
+.so man3/pthread_setschedparam.3
diff --git a/man/man3/pthread_getspecific.3 b/man/man3/pthread_getspecific.3
new file mode 100644
index 000000000..307a94752
--- /dev/null
+++ b/man/man3/pthread_getspecific.3
@@ -0,0 +1 @@
+.so man3/pthread_key_create.3
diff --git a/man/man3/pthread_join.3 b/man/man3/pthread_join.3
new file mode 100644
index 000000000..cbdd363ae
--- /dev/null
+++ b/man/man3/pthread_join.3
@@ -0,0 +1,134 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_join 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_join \- join with a terminated thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_join(pthread_t " thread ", void **" retval );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_join ()
+function waits for the thread specified by
+.I thread
+to terminate.
+If that thread has already terminated, then
+.BR pthread_join ()
+returns immediately.
+The thread specified by
+.I thread
+must be joinable.
+.P
+If
+.I retval
+is not NULL, then
+.BR pthread_join ()
+copies the exit status of the target thread
+(i.e., the value that the target thread supplied to
+.BR pthread_exit (3))
+into the location pointed to by
+.IR retval .
+If the target thread was canceled, then
+.B PTHREAD_CANCELED
+is placed in the location pointed to by
+.IR retval .
+.P
+If multiple threads simultaneously try to join with the same thread,
+the results are undefined.
+If the thread calling
+.BR pthread_join ()
+is canceled, then the target thread will remain joinable
+(i.e., it will not be detached).
+.SH RETURN VALUE
+On success,
+.BR pthread_join ()
+returns 0;
+on error, it returns an error number.
+.SH ERRORS
+.TP
+.B EDEADLK
+A deadlock was detected
+.\" The following verified by testing on glibc 2.8/NPTL:
+(e.g., two threads tried to join with each other);
+or
+.\" The following verified by testing on glibc 2.8/NPTL:
+.I thread
+specifies the calling thread.
+.TP
+.B EINVAL
+.I thread
+is not a joinable thread.
+.TP
+.B EINVAL
+Another thread is already waiting to join with this thread.
+.\" POSIX.1-2001 does not specify this error case.
+.TP
+.B ESRCH
+No thread with the ID
+.I thread
+could be found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_join ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+After a successful call to
+.BR pthread_join (),
+the caller is guaranteed that the target thread has terminated.
+The caller may then choose to do any clean-up that is required
+after termination of the thread (e.g., freeing memory or other
+resources that were allocated to the target thread).
+.P
+Joining with a thread that has previously been joined results in
+undefined behavior.
+.P
+Failure to join with a thread that is joinable
+(i.e., one that is not detached),
+produces a "zombie thread".
+Avoid doing this,
+since each zombie thread consumes some system resources,
+and when enough zombie threads have accumulated,
+it will no longer be possible to create new threads (or processes).
+.P
+There is no pthreads analog of
+.IR "waitpid(\-1,\ &status,\ 0)" ,
+that is, "join with any terminated thread".
+If you believe you need this functionality,
+you probably need to rethink your application design.
+.P
+All of the threads in a process are peers:
+any thread can join with any other thread in the process.
+.SH EXAMPLES
+See
+.BR pthread_create (3).
+.SH SEE ALSO
+.BR pthread_cancel (3),
+.BR pthread_create (3),
+.BR pthread_detach (3),
+.BR pthread_exit (3),
+.BR pthread_tryjoin_np (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_key_create.3 b/man/man3/pthread_key_create.3
new file mode 100644
index 000000000..ad8a397f4
--- /dev/null
+++ b/man/man3/pthread_key_create.3
@@ -0,0 +1,178 @@
+.\" Copyright, Xavier Leroy <Xavier.Leroy@inria.fr>
+.\" Copyright 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_key_create 3 (date) "Linux man-pages (unreleased)"
+.
+.
+.SH NAME
+pthread_key_create,
+pthread_key_delete,
+pthread_setspecific,
+pthread_getspecific
+\-
+management of thread-specific data
+.
+.
+.SH SYNOPSIS
+.B #include <pthread.h>
+.P
+.BI "int pthread_key_create(pthread_key_t *" key ", void (*" destr_function ") (void *));"
+.BI "int pthread_key_delete(pthread_key_t " key ");"
+.BI "int pthread_setspecific(pthread_key_t " key ", const void *" pointer ");"
+.BI "void * pthread_getspecific(pthread_key_t " key ");"
+.
+.
+.SH DESCRIPTION
+Programs often need global or static variables
+that have different values in different threads.
+Since threads share one memory space,
+this cannot be achieved with regular variables.
+Thread-specific data is the POSIX threads answer to this need.
+.P
+Each thread possesses a private memory block,
+the thread-specific data area,
+or TSD area for short.
+This area is indexed by TSD keys.
+The TSD area associates values of type \fBvoid *\fP to TSD keys.
+TSD keys are common to all threads,
+but the value associated with a given TSD key
+can be different in each thread.
+.P
+For concreteness,
+the TSD areas can be viewed as arrays of \fBvoid *\fP pointers,
+TSD keys as integer indices into these arrays,
+and the value of a TSD key
+as the value of the corresponding array element in the calling thread.
+.P
+When a thread is created,
+its TSD area initially associates \fBNULL\fP with all keys.
+.P
+\fBpthread_key_create\fP allocates a new TSD key.
+The key is stored in the location pointed to by \fIkey\fP.
+There is a limit of \fBPTHREAD_KEYS_MAX\fP
+on the number of keys allocated at a given time.
+The value initially associated with the returned key
+is \fBNULL\fP in all currently executing threads.
+.P
+The \fIdestr_function\fP argument,
+if not \fBNULL\fP,
+specifies a destructor function associated with the key.
+When a thread terminates via \fBpthread_exit\fP or by cancelation,
+\fIdestr_function\fP is called with arguments
+the value associated with the key in that thread.
+The \fIdestr_function\fP is not called if that value is \fBNULL\fP.
+The order in which destructor functions are called at thread termination time
+is unspecified.
+.P
+Before the destructor function is called,
+the \fBNULL\fP value is associated with the key in the current thread.
+A destructor function might,
+however,
+re-associate non-\fBNULL\fP values to that key or some other key.
+To deal with this,
+if after all the destructors have been called
+for all non-\fBNULL\fP values,
+there are still some non-\fBNULL\fP values with associated destructors,
+then the process is repeated.
+The glibc implementation stops the process
+after \fBPTHREAD_DESTRUCTOR_ITERATIONS\fP iterations,
+even if some non-\fBNULL\fP values with associated descriptors remain.
+Other implementations may loop indefinitely.
+.P
+\fBpthread_key_delete\fP deallocates a TSD key.
+It does not check
+whether non-\fBNULL\fP values are associated with that key
+in the currently executing threads,
+nor call the destructor function associated with the key.
+.P
+\fBpthread_setspecific\fP changes the value
+associated with \fIkey\fP in the calling thread,
+storing the given \fIpointer\fP instead.
+.P
+\fBpthread_getspecific\fP returns the value
+currently associated with \fIkey\fP in the calling thread.
+.
+.
+.SH "RETURN VALUE"
+\fBpthread_key_create\fP,
+\fBpthread_key_delete\fP,
+and \fBpthread_setspecific\fP
+return 0 on success and a non-zero error code on failure.
+If successful,
+\fBpthread_key_create\fP stores the newly allocated key
+in the location pointed to by its \fIkey\fP argument.
+.P
+\fBpthread_getspecific\fP returns
+the value associated with \fIkey\fP on success,
+and \fBNULL\fP on error.
+.
+.
+.SH ERRORS
+\fBpthread_key_create\fP returns the following error code on error:
+.RS
+.TP
+\fBEAGAIN\fP
+\fBPTHREAD_KEYS_MAX\fP keys are already allocated.
+.RE
+.P
+\fBpthread_key_delete\fP and \fBpthread_setspecific\fP return
+the following error code on error:
+.RS
+.TP
+\fBEINVAL\fP
+\fIkey\fP is not a valid, allocated TSD key.
+.RE
+.P
+\fBpthread_getspecific\fP returns \fBNULL\fP if \fIkey\fP is not a valid,
+allocated TSD key.
+.
+.
+.SH "SEE ALSO"
+pthread_create(3), pthread_exit(3), pthread_testcancel(3).
+.
+.
+.SH EXAMPLE
+The following code fragment
+allocates a thread-specific array of 100 characters,
+with automatic reclamation at thread exit:
+.P
+.RS
+.ft 3
+.nf
+.sp
+/* Key for the thread-specific buffer */
+static pthread_key_t buffer_key;
+\&
+/* Once-only initialisation of the key */
+static pthread_once_t buffer_key_once = PTHREAD_ONCE_INIT;
+\&
+/* Allocate the thread-specific buffer */
+void buffer_alloc(void)
+{
+  pthread_once(&buffer_key_once, buffer_key_alloc);
+  pthread_setspecific(buffer_key, malloc(100));
+}
+\&
+/* Return the thread-specific buffer */
+char * get_buffer(void)
+{
+  return (char *) pthread_getspecific(buffer_key);
+}
+\&
+/* Allocate the key */
+static void buffer_key_alloc()
+{
+  pthread_key_create(&buffer_key, buffer_destroy);
+}
+\&
+/* Free the thread-specific buffer */
+static void buffer_destroy(void * buf)
+{
+  free(buf);
+}
+.ft
+.P
+.RE
+.fi
diff --git a/man/man3/pthread_key_delete.3 b/man/man3/pthread_key_delete.3
new file mode 100644
index 000000000..307a94752
--- /dev/null
+++ b/man/man3/pthread_key_delete.3
@@ -0,0 +1 @@
+.so man3/pthread_key_create.3
diff --git a/man/man3/pthread_kill.3 b/man/man3/pthread_kill.3
new file mode 100644
index 000000000..5f158293e
--- /dev/null
+++ b/man/man3/pthread_kill.3
@@ -0,0 +1,108 @@
+'\" t
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_kill 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_kill \- send a signal to a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int pthread_kill(pthread_t " thread ", int " sig );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_kill ():
+.nf
+    _POSIX_C_SOURCE >= 199506L || _XOPEN_SOURCE >= 500
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_kill ()
+function sends the signal
+.I sig
+to
+.IR thread ,
+a thread in the same process as the caller.
+The signal is asynchronously directed to
+.IR thread .
+.P
+If
+.I sig
+is 0, then no signal is sent, but error checking is still performed.
+.SH RETURN VALUE
+On success,
+.BR pthread_kill ()
+returns 0;
+on error, it returns an error number, and no signal is sent.
+.SH ERRORS
+.TP
+.B EINVAL
+An invalid signal was specified.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_kill ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The glibc implementation of
+.BR pthread_kill ()
+gives an error
+.RB ( EINVAL )
+on attempts to send either of the real-time signals
+used internally by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.P
+POSIX.1-2008 recommends that if an implementation detects the use
+of a thread ID after the end of its lifetime,
+.BR pthread_kill ()
+should return the error
+.BR ESRCH .
+The glibc implementation returns this error in the cases where
+an invalid thread ID can be detected.
+But note also that POSIX says that an attempt to use a thread ID whose
+lifetime has ended produces undefined behavior,
+and an attempt to use an invalid thread ID in a call to
+.BR pthread_kill ()
+can, for example, cause a segmentation fault.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+Signal dispositions are process-wide:
+if a signal handler is installed,
+the handler will be invoked in the thread
+.IR thread ,
+but if the disposition of the signal is "stop", "continue", or "terminate",
+this action will affect the whole process.
+.SH SEE ALSO
+.BR kill (2),
+.BR sigaction (2),
+.BR sigpending (2),
+.BR pthread_self (3),
+.BR pthread_sigmask (3),
+.BR raise (3),
+.BR pthreads (7),
+.BR signal (7)
diff --git a/man/man3/pthread_kill_other_threads_np.3 b/man/man3/pthread_kill_other_threads_np.3
new file mode 100644
index 000000000..4689000b6
--- /dev/null
+++ b/man/man3/pthread_kill_other_threads_np.3
@@ -0,0 +1,69 @@
+'\" t
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_kill_other_threads_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_kill_other_threads_np \- terminate all other threads in process
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.B void pthread_kill_other_threads_np(void);
+.fi
+.SH DESCRIPTION
+.BR pthread_kill_other_threads_np ()
+has an effect only in the LinuxThreads threading implementation.
+On that implementation,
+calling this function causes the immediate termination of
+all threads in the application,
+except the calling thread.
+The cancelation state and cancelation type of the
+to-be-terminated threads are ignored,
+and the cleanup handlers are not called in those threads.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_kill_other_threads_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+In the NPTL threading implementation,
+.BR pthread_kill_other_threads_np ()
+exists, but does nothing.
+(Nothing needs to be done,
+because the implementation does the right thing during an
+.BR execve (2).)
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the name.
+.SH HISTORY
+glibc 2.0
+.SH NOTES
+.BR pthread_kill_other_threads_np ()
+is intended to be called just before a thread calls
+.BR execve (2)
+or a similar function.
+This function is designed to address a limitation in the obsolete
+LinuxThreads implementation whereby the other threads of an application
+are not automatically terminated (as POSIX.1-2001 requires) during
+.BR execve (2).
+.SH SEE ALSO
+.BR execve (2),
+.BR pthread_cancel (3),
+.BR pthread_setcancelstate (3),
+.BR pthread_setcanceltype (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_mutex_consistent.3 b/man/man3/pthread_mutex_consistent.3
new file mode 100644
index 000000000..372ed0d35
--- /dev/null
+++ b/man/man3/pthread_mutex_consistent.3
@@ -0,0 +1,86 @@
+.\" Copyright (c) 2017, Yubin Ruan <ablacktshirt@gmail.com>
+.\" and Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_mutex_consistent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_mutex_consistent \- make a robust mutex consistent
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_mutex_consistent(pthread_mutex_t *" mutex ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_mutex_consistent ():
+.nf
+    _POSIX_C_SOURCE >= 200809L
+.fi
+.SH DESCRIPTION
+This function makes a robust mutex consistent if it is in an inconsistent
+state.
+A mutex can be left in an inconsistent state if its owner terminates
+while holding the mutex, in which case the next owner who acquires the
+mutex will succeed and be notified by a return value of
+.B EOWNERDEAD
+from a call to
+.BR pthread_mutex_lock ().
+.SH RETURN VALUE
+On success,
+.IR pthread_mutex_consistent ()
+returns 0.
+Otherwise,
+it returns a positive error number to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The mutex is either not robust or is not in an inconsistent state.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.12.
+POSIX.1-2008.
+.P
+Before the addition of
+.BR pthread_mutex_consistent ()
+to POSIX,
+glibc defined the following equivalent nonstandard function if
+.B _GNU_SOURCE
+was defined:
+.P
+.nf
+.B [[deprecated]]
+.BI "int pthread_mutex_consistent_np(const pthread_mutex_t *" mutex );
+.fi
+.P
+This GNU-specific API, which first appeared in glibc 2.4,
+is nowadays obsolete and should not be used in new programs;
+since glibc 2.34 it has been marked as deprecated.
+.SH NOTES
+.BR pthread_mutex_consistent ()
+simply informs the implementation that the state (shared data)
+guarded by the mutex has been restored to a consistent state and that
+normal operations can now be performed with the mutex.
+It is the application's responsibility to ensure that the
+shared data has been restored to a consistent state before calling
+.BR pthread_mutex_consistent ().
+.SH EXAMPLES
+See
+.BR pthread_mutexattr_setrobust (3).
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_mutex_lock (3),
+.BR pthread_mutexattr_getrobust (3),
+.BR pthread_mutexattr_init (3),
+.BR pthread_mutexattr_setrobust (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_mutex_consistent_np.3 b/man/man3/pthread_mutex_consistent_np.3
new file mode 100644
index 000000000..a45bea431
--- /dev/null
+++ b/man/man3/pthread_mutex_consistent_np.3
@@ -0,0 +1 @@
+.so man3/pthread_mutex_consistent.3
diff --git a/man/man3/pthread_mutex_destroy.3 b/man/man3/pthread_mutex_destroy.3
new file mode 100644
index 000000000..1b7eb83b1
--- /dev/null
+++ b/man/man3/pthread_mutex_destroy.3
@@ -0,0 +1 @@
+.so man3/pthread_mutex_init.3
diff --git a/man/man3/pthread_mutex_init.3 b/man/man3/pthread_mutex_init.3
new file mode 100644
index 000000000..d9b1c5267
--- /dev/null
+++ b/man/man3/pthread_mutex_init.3
@@ -0,0 +1,241 @@
+.\" Copyright, Xavier Leroy <Xavier.Leroy@inria.fr>
+.\" Copyright 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_mutex_init 3 (date) "Linux man-pages (unreleased)"
+.
+.
+.SH NAME
+pthread_mutex_init,
+pthread_mutex_lock,
+pthread_mutex_trylock,
+pthread_mutex_unlock,
+pthread_mutex_destroy
+\-
+operations on mutexes
+.
+.
+.SH SYNOPSIS
+.B #include <pthread.h>
+.P
+.BI "pthread_mutex_t " fastmutex " = PTHREAD_MUTEX_INITIALIZER;"
+.BI "pthread_mutex_t " recmutex " = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;"
+.BI "pthread_mutex_t " errchkmutex " = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP;"
+.P
+.BI "int pthread_mutex_init(pthread_mutex_t *" mutex ", const pthread_mutexattr_t *" mutexattr ");"
+.BI "int pthread_mutex_lock(pthread_mutex_t *" mutex ");"
+.BI "int pthread_mutex_trylock(pthread_mutex_t *" mutex ");"
+.BI "int pthread_mutex_unlock(pthread_mutex_t *" mutex ");"
+.BI "int pthread_mutex_destroy(pthread_mutex_t *" mutex ");"
+.
+.
+.SH DESCRIPTION
+A mutex is a MUTual EXclusion device,
+and is useful for
+protecting shared data structures from concurrent modifications,
+and implementing critical sections and monitors.
+.P
+A mutex has two possible states:
+unlocked (not owned by any thread),
+and locked (owned by one thread).
+A mutex can never be owned by two different threads simultaneously.
+A thread attempting to lock a mutex
+that is already locked by another thread
+is suspended until the owning thread unlocks the mutex first.
+.P
+\fBpthread_mutex_init\fP initializes the mutex object pointed to by \fImutex\fP
+according to the mutex attributes specified in \fImutexattr\fP.
+If \fImutexattr\fP is \fBNULL\fP,
+default attributes are used instead.
+.P
+The LinuxThreads implementation supports only one mutex attributes,
+the \fImutex kind\fP,
+which is either ``fast'',
+``recursive'',
+or ``error checking''.
+The kind of a mutex determines
+whether it can be locked again by a thread that already owns it.
+The default kind is ``fast''.
+See \fBpthread_mutexattr_init\fP(3) for more information on mutex attributes.
+.P
+Variables of type \fBpthread_mutex_t\fP can also be initialized statically,
+using the constants
+\fBPTHREAD_MUTEX_INITIALIZER\fP
+(for fast mutexes),
+\fBPTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP\fP
+(for recursive mutexes),
+and \fBPTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP\fP
+(for error checking mutexes).
+.P
+\fBpthread_mutex_lock\fP locks the given mutex.
+If the mutex is currently unlocked,
+it becomes locked and owned by the calling thread,
+and \fBpthread_mutex_lock\fP returns immediately.
+If the mutex is already locked by another thread,
+\fBpthread_mutex_lock\fP suspends the calling thread
+until the mutex is unlocked.
+.P
+If the mutex is already locked by the calling thread,
+the behavior of \fBpthread_mutex_lock\fP depends on the kind of the mutex.
+If the mutex is of the ``fast'' kind,
+the calling thread is suspended until the mutex is unlocked,
+thus effectively causing the calling thread to deadlock.
+If the mutex is of the ``error checking'' kind,
+\fBpthread_mutex_lock\fP returns immediately with the error code \fBEDEADLK\fP.
+If the mutex is of the ``recursive'' kind,
+\fBpthread_mutex_lock\fP succeeds and returns immediately,
+recording the number of times the calling thread has locked the mutex.
+An equal number of \fBpthread_mutex_unlock\fP operations
+must be performed before the mutex returns to the unlocked state.
+.P
+\fBpthread_mutex_trylock\fP behaves identically to \fBpthread_mutex_lock\fP,
+except that it does not block the calling thread
+if the mutex is already locked by another thread
+(or by the calling thread in the case of a ``fast'' mutex).
+Instead,
+\fBpthread_mutex_trylock\fP returns immediately
+with the error code \fBEBUSY\fP.
+.P
+\fBpthread_mutex_unlock\fP unlocks the given mutex.
+The mutex is assumed to be locked and owned by the calling thread
+on entrance to \fBpthread_mutex_unlock\fP.
+If the mutex is of the ``fast'' kind,
+\fBpthread_mutex_unlock\fP always returns it to the unlocked state.
+If it is of the ``recursive'' kind,
+it decrements the locking count of the mutex
+(number of \fBpthread_mutex_lock\fP operations
+performed on it by the calling thread),
+and only when this count reaches zero is the mutex actually unlocked.
+.P
+On ``error checking'' and ``recursive'' mutexes,
+\fBpthread_mutex_unlock\fP actually checks at run-time
+that the mutex is locked on entrance,
+and that it was locked by the same thread
+that is now calling \fBpthread_mutex_unlock\fP.
+If these conditions are not met,
+an error code is returned and the mutex remains unchanged.
+``Fast'' mutexes perform no such checks,
+thus allowing a locked mutex to be
+unlocked by a thread other than its owner.
+This is non-portable behavior and must not be relied upon.
+.P
+\fBpthread_mutex_destroy\fP destroys a mutex object,
+freeing the resources it might hold.
+The mutex must be unlocked on entrance.
+In the LinuxThreads implementation,
+no resources are associated with mutex objects,
+thus \fBpthread_mutex_destroy\fP actually does nothing
+except checking that the mutex is unlocked.
+.
+.
+.SH CANCELLATION
+None of the mutex functions is a cancelation point,
+not even \fBpthread_mutex_lock\fP,
+in spite of the fact that it can suspend a thread for arbitrary durations.
+This way,
+the status of mutexes at cancelation points is predictable,
+allowing cancelation handlers
+to unlock precisely those mutexes that need to be unlocked
+before the thread stops executing.
+Consequently,
+threads using deferred cancelation
+should never hold a mutex for extended periods of time.
+.
+.
+.SH "ASYNC-SIGNAL SAFETY"
+The mutex functions are not async-signal safe.
+What this means is that they should not be called from a signal handler.
+In particular,
+calling \fBpthread_mutex_lock\fP or \fBpthread_mutex_unlock\fP
+from a signal handler
+may deadlock the calling thread.
+.
+.
+.SH "RETURN VALUE"
+\fBpthread_mutex_init\fP always returns 0.
+The other mutex functions
+return 0 on success and a non-zero error code on error.
+.
+.
+.SH ERRORS
+The \fBpthread_mutex_lock\fP function returns
+the following error code on error:
+.RS
+.TP
+\fBEINVAL\fP
+The mutex has not been properly initialized.
+.TP
+\fBEDEADLK\fP
+The mutex is already locked by the calling thread
+(``error checking'' mutexes only).
+.RE
+.P
+The \fBpthread_mutex_trylock\fP function returns
+the following error codes on error:
+.RS
+.TP
+\fBEBUSY\fP
+The mutex could not be acquired because it was currently locked.
+.TP
+\fBEINVAL\fP
+The mutex has not been properly initialized.
+.RE
+.P
+The \fBpthread_mutex_unlock\fP function returns
+the following error code on error:
+.RS
+.TP
+\fBEINVAL\fP
+The mutex has not been properly initialized.
+.TP
+\fBEPERM\fP
+The calling thread does not own the mutex
+(``error checking'' mutexes only).
+.RE
+.P
+The \fBpthread_mutex_destroy\fP function returns
+the following error code on error:
+.RS
+.TP
+\fBEBUSY\fP
+The mutex is currently locked.
+.RE
+.
+.
+.SH "SEE ALSO"
+\fBpthread_mutexattr_init\fP(3),
+\fBpthread_mutexattr_setkind_np\fP(3),
+\fBpthread_cancel\fP(3).
+.
+.
+.SH EXAMPLE
+A shared global variable \fIx\fP can be protected by a mutex as follows:
+.P
+.RS
+.ft 3
+.nf
+.sp
+int x;
+pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER;
+.ft
+.P
+.RE
+.fi
+.P
+All accesses and modifications to \fIx\fP
+should be bracketed by calls to
+\fBpthread_mutex_lock\fP and \fBpthread_mutex_unlock\fP
+as follows:
+.P
+.RS
+.ft 3
+.nf
+.sp
+pthread_mutex_lock(&mut);
+/* operate on x */
+pthread_mutex_unlock(&mut);
+.ft
+.P
+.RE
+.fi
diff --git a/man/man3/pthread_mutex_lock.3 b/man/man3/pthread_mutex_lock.3
new file mode 100644
index 000000000..1b7eb83b1
--- /dev/null
+++ b/man/man3/pthread_mutex_lock.3
@@ -0,0 +1 @@
+.so man3/pthread_mutex_init.3
diff --git a/man/man3/pthread_mutex_trylock.3 b/man/man3/pthread_mutex_trylock.3
new file mode 100644
index 000000000..1b7eb83b1
--- /dev/null
+++ b/man/man3/pthread_mutex_trylock.3
@@ -0,0 +1 @@
+.so man3/pthread_mutex_init.3
diff --git a/man/man3/pthread_mutex_unlock.3 b/man/man3/pthread_mutex_unlock.3
new file mode 100644
index 000000000..1b7eb83b1
--- /dev/null
+++ b/man/man3/pthread_mutex_unlock.3
@@ -0,0 +1 @@
+.so man3/pthread_mutex_init.3
diff --git a/man/man3/pthread_mutexattr_destroy.3 b/man/man3/pthread_mutexattr_destroy.3
new file mode 100644
index 000000000..eadaa9b83
--- /dev/null
+++ b/man/man3/pthread_mutexattr_destroy.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_init.3
diff --git a/man/man3/pthread_mutexattr_getkind_np.3 b/man/man3/pthread_mutexattr_getkind_np.3
new file mode 100644
index 000000000..af2ab9681
--- /dev/null
+++ b/man/man3/pthread_mutexattr_getkind_np.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_setkind_np.3
diff --git a/man/man3/pthread_mutexattr_getpshared.3 b/man/man3/pthread_mutexattr_getpshared.3
new file mode 100644
index 000000000..34bf3a718
--- /dev/null
+++ b/man/man3/pthread_mutexattr_getpshared.3
@@ -0,0 +1,82 @@
+.\" Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_mutexattr_getpshared 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_mutexattr_getpshared, pthread_mutexattr_setpshared \- get/set
+process-shared mutex attribute
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.B int pthread_mutexattr_getpshared(
+.BI "                      const pthread_mutexattr_t *restrict " attr ,
+.BI "                      int *restrict " pshared );
+.BI "int pthread_mutexattr_setpshared(pthread_mutexattr_t *" attr ,
+.BI "                      int " pshared );
+.fi
+.SH DESCRIPTION
+These functions get and set the process-shared attribute
+in a mutex attributes object.
+This attribute must be appropriately set to ensure correct,
+efficient operation of a mutex created using this attributes object.
+.P
+The process-shared attribute can have one of the following values:
+.TP
+.B PTHREAD_PROCESS_PRIVATE
+Mutexes created with this attributes object are to be shared
+only among threads in the same process that initialized the mutex.
+This is the default value for the process-shared mutex attribute.
+.TP
+.B PTHREAD_PROCESS_SHARED
+Mutexes created with this attributes object can be shared between
+any threads that have access to the memory containing the object,
+including threads in different processes.
+.P
+.BR pthread_mutexattr_getpshared ()
+places the value of the process-shared attribute of
+the mutex attributes object referred to by
+.I attr
+in the location pointed to by
+.IR pshared .
+.P
+.BR pthread_mutexattr_setpshared ()
+sets the value of the process-shared attribute of
+the mutex attributes object referred to by
+.I attr
+to the value specified in
+.BR pshared .
+.P
+If
+.I attr
+does not refer to an initialized mutex attributes object,
+the behavior is undefined.
+.SH RETURN VALUE
+On success, these functions return 0.
+On error, they return a positive error number.
+.SH ERRORS
+.BR pthread_mutexattr_setpshared ()
+can fail with the following errors:
+.TP
+.B EINVAL
+The value specified in
+.I pshared
+is invalid.
+.TP
+.B ENOTSUP
+.I pshared is
+.B PTHREAD_PROCESS_SHARED
+but the implementation does not support process-shared mutexes.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_mutexattr_init (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_mutexattr_getrobust.3 b/man/man3/pthread_mutexattr_getrobust.3
new file mode 100644
index 000000000..8c40cc0a7
--- /dev/null
+++ b/man/man3/pthread_mutexattr_getrobust.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_setrobust.3
diff --git a/man/man3/pthread_mutexattr_getrobust_np.3 b/man/man3/pthread_mutexattr_getrobust_np.3
new file mode 100644
index 000000000..8c40cc0a7
--- /dev/null
+++ b/man/man3/pthread_mutexattr_getrobust_np.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_setrobust.3
diff --git a/man/man3/pthread_mutexattr_gettype.3 b/man/man3/pthread_mutexattr_gettype.3
new file mode 100644
index 000000000..eadaa9b83
--- /dev/null
+++ b/man/man3/pthread_mutexattr_gettype.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_init.3
diff --git a/man/man3/pthread_mutexattr_init.3 b/man/man3/pthread_mutexattr_init.3
new file mode 100644
index 000000000..7fff66b1d
--- /dev/null
+++ b/man/man3/pthread_mutexattr_init.3
@@ -0,0 +1,53 @@
+.\" Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_mutexattr_init 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_mutexattr_init, pthread_mutexattr_destroy \- initialize and
+destroy a mutex attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_mutexattr_init(pthread_mutexattr_t *" attr ");"
+.BI "int pthread_mutexattr_destroy(pthread_mutexattr_t *" attr ");"
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_mutexattr_init ()
+function initializes the mutex attributes object pointed to by
+.I attr
+with default values for all attributes defined by the implementation.
+.P
+The results of initializing an already initialized mutex attributes
+object are undefined.
+.P
+The
+.BR pthread_mutexattr_destroy ()
+function destroys a mutex attribute object (making it uninitialized).
+Once a mutex attributes object has been destroyed, it can be reinitialized with
+.BR pthread_mutexattr_init ().
+.P
+The results of destroying an uninitialized mutex attributes
+object are undefined.
+.SH RETURN VALUE
+On success, these functions return 0.
+On error, they return a positive error number.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+Subsequent changes to a mutex attributes object do not affect mutex that
+have already been initialized using that object.
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_mutex_init (3),
+.BR pthread_mutexattr_getpshared (3),
+.BR pthread_mutexattr_getrobust (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_mutexattr_setkind_np.3 b/man/man3/pthread_mutexattr_setkind_np.3
new file mode 100644
index 000000000..03c91534d
--- /dev/null
+++ b/man/man3/pthread_mutexattr_setkind_np.3
@@ -0,0 +1,52 @@
+.\" Copyright, Xavier Leroy <Xavier.Leroy@inria.fr>
+.\" Copyright 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_mutexattr_setkind_np 3 (date) "Linux man-pages (unreleased)"
+.
+.
+.SH NAME
+pthread_mutexattr_setkind_np,
+pthread_mutexattr_getkind_np
+\-
+deprecated mutex creation attributes
+.
+.
+.SH SYNOPSIS
+.B #include <pthread.h>
+.P
+.BI "int pthread_mutexattr_setkind_np(pthread_mutexattr_t *" attr ", int " kind ");"
+.BI "int pthread_mutexattr_getkind_np(const pthread_mutexattr_t *" attr ", int *" kind ");"
+.
+.
+.SH DESCRIPTION
+These functions are deprecated,
+use \fBpthread_mutexattr_settype\fP(3)
+and \fBpthread_mutexattr_gettype\fP(3)
+instead.
+.
+.
+.SH "RETURN VALUE"
+\fBpthread_mutexattr_getkind_np\fP always returns 0.
+.P
+\fBpthread_mutexattr_setkind_np\fP
+returns 0 on success and a non-zero error code on error.
+.
+.
+.SH ERRORS
+On error,
+\fBpthread_mutexattr_setkind_np\fP returns the following error code:
+.TP
+\fBEINVAL\fP
+\fIkind\fP is neither
+\fBPTHREAD_MUTEX_FAST_NP\fP
+nor
+\fBPTHREAD_MUTEX_RECURSIVE_NP\fP
+nor
+\fBPTHREAD_MUTEX_ERRORCHECK_NP\fP.
+.
+.
+.SH "SEE ALSO"
+\fBpthread_mutexattr_settype\fP(3),
+\fBpthread_mutexattr_gettype\fP(3).
diff --git a/man/man3/pthread_mutexattr_setpshared.3 b/man/man3/pthread_mutexattr_setpshared.3
new file mode 100644
index 000000000..07899fdfc
--- /dev/null
+++ b/man/man3/pthread_mutexattr_setpshared.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_getpshared.3
diff --git a/man/man3/pthread_mutexattr_setrobust.3 b/man/man3/pthread_mutexattr_setrobust.3
new file mode 100644
index 000000000..921d9e9c0
--- /dev/null
+++ b/man/man3/pthread_mutexattr_setrobust.3
@@ -0,0 +1,264 @@
+.\" Copyright (c) 2017, Yubin Ruan <ablacktshirt@gmail.com>
+.\" and Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_mutexattr_setrobust 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_mutexattr_getrobust, pthread_mutexattr_setrobust
+\- get and set the robustness attribute of a mutex attributes object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_mutexattr_getrobust(const pthread_mutexattr_t *" attr ,
+.BI "                                int *" robustness ");"
+.BI "int pthread_mutexattr_setrobust(pthread_mutexattr_t *" attr ,
+.BI "                                int " robustness ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_mutexattr_getrobust (),
+.BR pthread_mutexattr_setrobust ():
+.nf
+    _POSIX_C_SOURCE >= 200809L
+.\" FIXME .
+.\" But see https://sourceware.org/bugzilla/show_bug.cgi?id=22125
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_mutexattr_getrobust ()
+function places the value of the robustness attribute of
+the mutex attributes object referred to by
+.I attr
+in
+.IR *robustness .
+The
+.BR pthread_mutexattr_setrobust ()
+function sets the value of the robustness attribute of
+the mutex attributes object referred to by
+.I attr
+to the value specified in
+.IR *robustness .
+.P
+The robustness attribute specifies the behavior of the mutex when
+the owning thread dies without unlocking the mutex.
+The following values are valid for
+.IR robustness :
+.TP
+.B PTHREAD_MUTEX_STALLED
+This is the default value for a mutex attributes object.
+If a mutex is initialized with the
+.B PTHREAD_MUTEX_STALLED
+attribute and its owner dies without unlocking it,
+the mutex remains locked afterwards and any future attempts to call
+.BR pthread_mutex_lock (3)
+on the mutex will block indefinitely.
+.TP
+.B PTHREAD_MUTEX_ROBUST
+If a mutex is initialized with the
+.B PTHREAD_MUTEX_ROBUST
+attribute and its owner dies without unlocking it,
+any future attempts to call
+.BR pthread_mutex_lock (3)
+on this mutex will succeed and return
+.B EOWNERDEAD
+to indicate that the original owner no longer exists and the mutex is in
+an inconsistent state.
+Usually after
+.B EOWNERDEAD
+is returned, the next owner should call
+.BR pthread_mutex_consistent (3)
+on the acquired mutex to make it consistent again before using it any further.
+.IP
+If the next owner unlocks the mutex using
+.BR pthread_mutex_unlock (3)
+before making it consistent, the mutex will be permanently unusable and any
+subsequent attempts to lock it using
+.BR pthread_mutex_lock (3)
+will fail with the error
+.BR ENOTRECOVERABLE .
+The only permitted operation on such a mutex is
+.BR pthread_mutex_destroy (3).
+.IP
+If the next owner terminates before calling
+.BR pthread_mutex_consistent (3),
+further
+.BR pthread_mutex_lock (3)
+operations on this mutex will still return
+.BR EOWNERDEAD .
+.P
+Note that the
+.I attr
+argument of
+.BR pthread_mutexattr_getrobust ()
+and
+.BR pthread_mutexattr_setrobust ()
+should refer to a mutex attributes object that was initialized by
+.BR pthread_mutexattr_init (3),
+otherwise the behavior is undefined.
+.SH RETURN VALUE
+On success, these functions return 0.
+On error, they return a positive error number.
+.P
+In the glibc implementation,
+.BR pthread_mutexattr_getrobust ()
+always return zero.
+.SH ERRORS
+.TP
+.B EINVAL
+A value other than
+.B PTHREAD_MUTEX_STALLED
+or
+.B PTHREAD_MUTEX_ROBUST
+was passed to
+.BR pthread_mutexattr_setrobust ().
+.SH VERSIONS
+In the Linux implementation,
+when using process-shared robust mutexes, a waiting thread also receives the
+.B EOWNERDEAD
+notification if the owner of a robust mutex performs an
+.BR execve (2)
+without first unlocking the mutex.
+POSIX.1 does not specify this detail,
+but the same behavior also occurs in at least some
+.\" E.g., Solaris, according to its manual page
+other implementations.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.12.
+POSIX.1-2008.
+.P
+Before the addition of
+.BR pthread_mutexattr_getrobust ()
+and
+.BR pthread_mutexattr_setrobust ()
+to POSIX,
+glibc defined the following equivalent nonstandard functions if
+.B _GNU_SOURCE
+was defined:
+.P
+.nf
+.B [[deprecated]]
+.BI "int pthread_mutexattr_getrobust_np(const pthread_mutexattr_t *" attr ,
+.BI "                                   int *" robustness ");"
+.B [[deprecated]]
+.BI "int pthread_mutexattr_setrobust_np(const pthread_mutexattr_t *" attr ,
+.BI "                                   int " robustness ");"
+.fi
+.P
+Correspondingly, the constants
+.B PTHREAD_MUTEX_STALLED_NP
+and
+.B PTHREAD_MUTEX_ROBUST_NP
+were also defined.
+.P
+These GNU-specific APIs, which first appeared in glibc 2.4,
+are nowadays obsolete and should not be used in new programs;
+since glibc 2.34 these APIs are marked as deprecated.
+.SH EXAMPLES
+The program below demonstrates the use of the robustness attribute of a
+mutex attributes object.
+In this program, a thread holding the mutex
+dies prematurely without unlocking the mutex.
+The main thread subsequently acquires the mutex
+successfully and gets the error
+.BR EOWNERDEAD ,
+after which it makes the mutex consistent.
+.P
+The following shell session shows what we see when running this program:
+.P
+.in +4n
+.EX
+$ \fB./a.out\fP
+[original owner] Setting lock...
+[original owner] Locked. Now exiting without unlocking.
+[main] Attempting to lock the robust mutex.
+[main] pthread_mutex_lock() returned EOWNERDEAD
+[main] Now make the mutex consistent
+[main] Mutex is now consistent; unlocking
+.EE
+.in
+.SS Program source
+.\" SRC BEGIN (pthread_mutexattr_setrobust.c)
+.EX
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static pthread_mutex_t mtx;
+\&
+static void *
+original_owner_thread(void *ptr)
+{
+    printf("[original owner] Setting lock...\en");
+    pthread_mutex_lock(&mtx);
+    printf("[original owner] Locked. Now exiting without unlocking.\en");
+    pthread_exit(NULL);
+}
+\&
+int
+main(void)
+{
+    pthread_t thr;
+    pthread_mutexattr_t attr;
+    int s;
+\&
+    pthread_mutexattr_init(&attr);
+\&
+    pthread_mutexattr_setrobust(&attr, PTHREAD_MUTEX_ROBUST);
+\&
+    pthread_mutex_init(&mtx, &attr);
+\&
+    pthread_create(&thr, NULL, original_owner_thread, NULL);
+\&
+    sleep(2);
+\&
+    /* "original_owner_thread" should have exited by now. */
+\&
+    printf("[main] Attempting to lock the robust mutex.\en");
+    s = pthread_mutex_lock(&mtx);
+    if (s == EOWNERDEAD) {
+        printf("[main] pthread_mutex_lock() returned EOWNERDEAD\en");
+        printf("[main] Now make the mutex consistent\en");
+        s = pthread_mutex_consistent(&mtx);
+        if (s != 0)
+            handle_error_en(s, "pthread_mutex_consistent");
+        printf("[main] Mutex is now consistent; unlocking\en");
+        s = pthread_mutex_unlock(&mtx);
+        if (s != 0)
+            handle_error_en(s, "pthread_mutex_unlock");
+\&
+        exit(EXIT_SUCCESS);
+    } else if (s == 0) {
+        printf("[main] pthread_mutex_lock() unexpectedly succeeded\en");
+        exit(EXIT_FAILURE);
+    } else {
+        printf("[main] pthread_mutex_lock() unexpectedly failed\en");
+        handle_error_en(s, "pthread_mutex_lock");
+    }
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR get_robust_list (2),
+.BR set_robust_list (2),
+.BR pthread_mutex_consistent (3),
+.BR pthread_mutex_init (3),
+.BR pthread_mutex_lock (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_mutexattr_setrobust_np.3 b/man/man3/pthread_mutexattr_setrobust_np.3
new file mode 100644
index 000000000..8c40cc0a7
--- /dev/null
+++ b/man/man3/pthread_mutexattr_setrobust_np.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_setrobust.3
diff --git a/man/man3/pthread_mutexattr_settype.3 b/man/man3/pthread_mutexattr_settype.3
new file mode 100644
index 000000000..eadaa9b83
--- /dev/null
+++ b/man/man3/pthread_mutexattr_settype.3
@@ -0,0 +1 @@
+.so man3/pthread_mutexattr_init.3
diff --git a/man/man3/pthread_once.3 b/man/man3/pthread_once.3
new file mode 100644
index 000000000..17d25360f
--- /dev/null
+++ b/man/man3/pthread_once.3
@@ -0,0 +1,44 @@
+.\" Copyright, Xavier Leroy <Xavier.Leroy@inria.fr>
+.\" Copyright 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_once 3 (date) "Linux man-pages (unreleased)"
+.
+.
+.SH NAME
+pthread_once
+\-
+once-only initialization
+.
+.
+.SH SYNOPSIS
+.B #include <pthread.h>
+.P
+.BI "pthread_once_t " once_control " = PTHREAD_ONCE_INIT;"
+.P
+.BI "int pthread_once(pthread_once_t *" once_control ", void (*" init_routine ") (void));"
+.
+.
+.SH DESCRIPTION
+The purpose of \fBpthread_once\fP is
+to ensure that a piece of initialization code is executed at most once.
+The \fIonce_control\fP argument points to a static or extern variable
+statically initialized to \fBPTHREAD_ONCE_INIT\fP.
+.P
+The first time \fBpthread_once\fP is called
+with a given \fIonce_control\fP argument,
+it calls \fIinit_routine\fP with no argument
+and changes the value of the \fIonce_control\fP variable
+to record that initialization has been performed.
+Subsequent calls to \fBpthread_once\fP
+with the same \fBonce_control\fP argument
+do nothing.
+.
+.
+.SH "RETURN VALUE"
+\fBpthread_once\fP always returns 0.
+.
+.
+.SH ERRORS
+None.
diff --git a/man/man3/pthread_rwlockattr_getkind_np.3 b/man/man3/pthread_rwlockattr_getkind_np.3
new file mode 100644
index 000000000..6f3f740e7
--- /dev/null
+++ b/man/man3/pthread_rwlockattr_getkind_np.3
@@ -0,0 +1 @@
+.so man3/pthread_rwlockattr_setkind_np.3
diff --git a/man/man3/pthread_rwlockattr_setkind_np.3 b/man/man3/pthread_rwlockattr_setkind_np.3
new file mode 100644
index 000000000..5388a9ad3
--- /dev/null
+++ b/man/man3/pthread_rwlockattr_setkind_np.3
@@ -0,0 +1,119 @@
+.\"Copyright (c) 2010 Novell Inc., written by Robert Schweikert
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_rwlockattr_setkind_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_rwlockattr_setkind_np, pthread_rwlockattr_getkind_np \- set/get
+the read-write lock kind of the thread read-write lock attribute object
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_rwlockattr_setkind_np(pthread_rwlockattr_t *" attr ,
+.BI "                       int " pref );
+.B int pthread_rwlockattr_getkind_np(
+.BI "                       const pthread_rwlockattr_t *restrict " attr ,
+.BI "                       int *restrict " pref );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_rwlockattr_setkind_np (),
+.BR pthread_rwlockattr_getkind_np ():
+.nf
+    _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200809L
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_rwlockattr_setkind_np ()
+function sets the "lock kind" attribute of the
+read-write lock attribute object referred to by
+.I attr
+to the value specified in
+.IR pref .
+The argument
+.I pref
+may be set to one of the following:
+.TP
+.B PTHREAD_RWLOCK_PREFER_READER_NP
+This is the default.
+A thread may hold multiple read locks; that is, read locks are recursive.
+According to The Single Unix Specification, the behavior is unspecified when a
+reader tries to place a lock, and there is no write lock but writers are
+waiting.
+Giving preference to the reader, as is set by
+.BR PTHREAD_RWLOCK_PREFER_READER_NP ,
+implies that the reader will receive the requested lock, even if
+a writer is waiting.
+As long as there are readers, the writer will be
+starved.
+.TP
+.B PTHREAD_RWLOCK_PREFER_WRITER_NP
+This is intended as the write lock analog of
+.BR PTHREAD_RWLOCK_PREFER_READER_NP .
+This is ignored by glibc because the POSIX requirement to support
+recursive read locks would cause this option to create trivial
+deadlocks; instead use
+.B PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP
+which ensures the application developer will not take recursive
+read locks thus avoiding deadlocks.
+.\" ---
+.\" Here is the relevant wording:
+.\"
+.\"     A thread may hold multiple concurrent read locks on rwlock (that is,
+.\"     successfully call the pthread_rwlock_rdlock() function n times). If
+.\"     so, the thread must perform matching unlocks (that is, it must call
+.\"     the pthread_rwlock_unlock() function n times).
+.\"
+.\" By making write-priority work correctly, I broke the above requirement,
+.\" because I had no clue that recursive read locks are permissible.
+.\"
+.\" If a thread which holds a read lock tries to acquire another read lock,
+.\" and now one or more writers is waiting for a write lock, then the algorithm
+.\" will lead to an obvious deadlock. The reader will be suspended, waiting for
+.\" the writers to acquire and release the lock, and the writers will be
+.\" suspended waiting for every existing read lock to be released.
+.\" ---
+.\" https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_rwlock_rdlock.html
+.\" https://sourceware.org/legacy-ml/libc-alpha/2000-01/msg00055.html
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=7057
+.TP
+.B PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP
+Setting the lock kind to this
+avoids writer starvation as long as any read locking is not done in a
+recursive fashion.
+.P
+The
+.BR pthread_rwlockattr_getkind_np ()
+function returns the value of the lock kind attribute of the
+read-write lock attribute object referred to by
+.I attr
+in the pointer
+.IR pref .
+.SH RETURN VALUE
+On success, these functions return 0.
+Given valid pointer arguments,
+.BR pthread_rwlockattr_getkind_np ()
+always succeeds.
+On error,
+.BR pthread_rwlockattr_setkind_np ()
+returns a nonzero error number.
+.SH ERRORS
+.TP
+.B EINVAL
+.I pref
+specifies an unsupported value.
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the names.
+.SH HISTORY
+glibc 2.1.
+.SH SEE ALSO
+.BR pthreads (7)
diff --git a/man/man3/pthread_self.3 b/man/man3/pthread_self.3
new file mode 100644
index 000000000..9aa58314d
--- /dev/null
+++ b/man/man3/pthread_self.3
@@ -0,0 +1,77 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_self 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_self \- obtain ID of the calling thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.B pthread_t pthread_self(void);
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_self ()
+function returns the ID of the calling thread.
+This is the same value that is returned in
+.I *thread
+in the
+.BR pthread_create (3)
+call that created this thread.
+.SH RETURN VALUE
+This function always succeeds, returning the calling thread's ID.
+.SH ERRORS
+This function always succeeds.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_self ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+POSIX.1 allows an implementation wide freedom in choosing
+the type used to represent a thread ID;
+for example, representation using either an arithmetic type or
+a structure is permitted.
+Therefore, variables of type
+.I pthread_t
+can't portably be compared using the C equality operator (\fB==\fP);
+use
+.BR pthread_equal (3)
+instead.
+.P
+Thread identifiers should be considered opaque:
+any attempt to use a thread ID other than in pthreads calls
+is nonportable and can lead to unspecified results.
+.P
+Thread IDs are guaranteed to be unique only within a process.
+A thread ID may be reused after a terminated thread has been joined,
+or a detached thread has terminated.
+.P
+The thread ID returned by
+.BR pthread_self ()
+is not the same thing as the kernel thread ID returned by a call to
+.BR gettid (2).
+.SH SEE ALSO
+.BR pthread_create (3),
+.BR pthread_equal (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_setaffinity_np.3 b/man/man3/pthread_setaffinity_np.3
new file mode 100644
index 000000000..4e7147321
--- /dev/null
+++ b/man/man3/pthread_setaffinity_np.3
@@ -0,0 +1,207 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_setaffinity_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_setaffinity_np, pthread_getaffinity_np \- set/get
+CPU affinity of a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.BI "int pthread_setaffinity_np(pthread_t " thread ", size_t " cpusetsize ,
+.BI "                           const cpu_set_t *" cpuset );
+.BI "int pthread_getaffinity_np(pthread_t " thread ", size_t " cpusetsize ,
+.BI "                           cpu_set_t *" cpuset );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_setaffinity_np ()
+function
+sets the CPU affinity mask of the thread
+.I thread
+to the CPU set pointed to by
+.IR cpuset .
+If the call is successful,
+and the thread is not currently running on one of the CPUs in
+.IR cpuset ,
+then it is migrated to one of those CPUs.
+.P
+The
+.BR pthread_getaffinity_np ()
+function returns the CPU affinity mask of the thread
+.I thread
+in the buffer pointed to by
+.IR cpuset .
+.P
+For more details on CPU affinity masks, see
+.BR sched_setaffinity (2).
+For a description of a set of macros
+that can be used to manipulate and inspect CPU sets, see
+.BR CPU_SET (3).
+.P
+The argument
+.I cpusetsize
+is the length (in bytes) of the buffer pointed to by
+.IR cpuset .
+Typically, this argument would be specified as
+.IR sizeof(cpu_set_t) .
+(It may be some other value, if using the macros described in
+.BR CPU_SET (3)
+for dynamically allocating a CPU set.)
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+.TP
+.B EFAULT
+A supplied memory address was invalid.
+.TP
+.B EINVAL
+.RB ( pthread_setaffinity_np ())
+The affinity bit mask
+.I mask
+contains no processors that are currently physically on the system
+and permitted to the thread according to any restrictions that
+may be imposed by the "cpuset" mechanism described in
+.BR cpuset (7).
+.TP
+.B EINVAL
+.RB ( pthread_setaffinity_np ())
+.I cpuset
+specified a CPU that was outside the set supported by the kernel.
+(The kernel configuration option
+.B CONFIG_NR_CPUS
+defines the range of the set supported by the kernel data type
+.\" cpumask_t
+used to represent CPU sets.)
+.\" The raw sched_getaffinity() system call returns the size (in bytes)
+.\" of the cpumask_t type.
+.TP
+.B EINVAL
+.RB ( pthread_getaffinity_np ())
+.I cpusetsize
+is smaller than the size of the affinity mask used by the kernel.
+.TP
+.B ESRCH
+No thread with the ID
+.I thread
+could be found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_setaffinity_np (),
+.BR pthread_getaffinity_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the names.
+.SH HISTORY
+glibc 2.3.4.
+.P
+In glibc 2.3.3 only,
+versions of these functions were provided that did not have a
+.I cpusetsize
+argument.
+Instead the CPU set size given to the underlying system calls was always
+.IR sizeof(cpu_set_t) .
+.SH NOTES
+After a call to
+.BR pthread_setaffinity_np (),
+the set of CPUs on which the thread will actually run is
+the intersection of the set specified in the
+.I cpuset
+argument and the set of CPUs actually present on the system.
+The system may further restrict the set of CPUs on which the thread
+runs if the "cpuset" mechanism described in
+.BR cpuset (7)
+is being used.
+These restrictions on the actual set of CPUs on which the thread
+will run are silently imposed by the kernel.
+.P
+These functions are implemented on top of the
+.BR sched_setaffinity (2)
+and
+.BR sched_getaffinity (2)
+system calls.
+.P
+A new thread created by
+.BR pthread_create (3)
+inherits a copy of its creator's CPU affinity mask.
+.SH EXAMPLES
+In the following program, the main thread uses
+.BR pthread_setaffinity_np ()
+to set its CPU affinity mask to include CPUs 0 to 7
+(which may not all be available on the system),
+and then calls
+.BR pthread_getaffinity_np ()
+to check the resulting CPU affinity mask of the thread.
+.P
+.\" SRC BEGIN (pthread_setaffinity_np.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    int s;
+    cpu_set_t cpuset;
+    pthread_t thread;
+\&
+    thread = pthread_self();
+\&
+    /* Set affinity mask to include CPUs 0 to 7. */
+\&
+    CPU_ZERO(&cpuset);
+    for (size_t j = 0; j < 8; j++)
+        CPU_SET(j, &cpuset);
+\&
+    s = pthread_setaffinity_np(thread, sizeof(cpuset), &cpuset);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_setaffinity_np");
+\&
+    /* Check the actual affinity mask assigned to the thread. */
+\&
+    s = pthread_getaffinity_np(thread, sizeof(cpuset), &cpuset);
+    if (s != 0)
+        errc(EXIT_FAILURE, s, "pthread_getaffinity_np");
+\&
+    printf("Set returned by pthread_getaffinity_np() contained:\en");
+    for (size_t j = 0; j < CPU_SETSIZE; j++)
+        if (CPU_ISSET(j, &cpuset))
+            printf("    CPU %zu\en", j);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR sched_setaffinity (2),
+.BR CPU_SET (3),
+.BR pthread_attr_setaffinity_np (3),
+.BR pthread_self (3),
+.BR sched_getcpu (3),
+.BR cpuset (7),
+.BR pthreads (7),
+.BR sched (7)
diff --git a/man/man3/pthread_setattr_default_np.3 b/man/man3/pthread_setattr_default_np.3
new file mode 100644
index 000000000..1ea2ab65b
--- /dev/null
+++ b/man/man3/pthread_setattr_default_np.3
@@ -0,0 +1 @@
+.so man3/pthread_getattr_default_np.3
diff --git a/man/man3/pthread_setcancelstate.3 b/man/man3/pthread_setcancelstate.3
new file mode 100644
index 000000000..287907657
--- /dev/null
+++ b/man/man3/pthread_setcancelstate.3
@@ -0,0 +1,200 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_setcancelstate 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_setcancelstate, pthread_setcanceltype \-
+set cancelability state and type
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_setcancelstate(int " state ", int *" oldstate );
+.BI "int pthread_setcanceltype(int " type ", int *" oldtype );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_setcancelstate ()
+sets the cancelability state of the calling thread to the value
+given in
+.IR state .
+The previous cancelability state of the thread is returned
+in the buffer pointed to by
+.IR oldstate .
+The
+.I state
+argument must have one of the following values:
+.TP
+.B PTHREAD_CANCEL_ENABLE
+The thread is cancelable.
+This is the default cancelability state in all new threads,
+including the initial thread.
+The thread's cancelability type determines when a cancelable thread
+will respond to a cancelation request.
+.TP
+.B PTHREAD_CANCEL_DISABLE
+The thread is not cancelable.
+If a cancelation request is received,
+it is blocked until cancelability is enabled.
+.P
+The
+.BR pthread_setcanceltype ()
+sets the cancelability type of the calling thread to the value
+given in
+.IR type .
+The previous cancelability type of the thread is returned
+in the buffer pointed to by
+.IR oldtype .
+The
+.I type
+argument must have one of the following values:
+.TP
+.B PTHREAD_CANCEL_DEFERRED
+A cancelation request is deferred until the thread next calls
+a function that is a cancelation point (see
+.BR pthreads (7)).
+This is the default cancelability type in all new threads,
+including the initial thread.
+.IP
+Even with deferred cancelation, a
+cancelation point in an asynchronous signal handler may still
+be acted upon and the effect is as if it was an asynchronous
+cancelation.
+.TP
+.B PTHREAD_CANCEL_ASYNCHRONOUS
+The thread can be canceled at any time.
+(Typically,
+it will be canceled immediately upon receiving a cancelation request,
+but the system doesn't guarantee this.)
+.P
+The set-and-get operation performed by each of these functions
+is atomic with respect to other threads in the process
+calling the same function.
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+The
+.BR pthread_setcancelstate ()
+can fail with the following error:
+.TP
+.B EINVAL
+Invalid value for
+.IR state .
+.P
+The
+.BR pthread_setcanceltype ()
+can fail with the following error:
+.TP
+.B EINVAL
+Invalid value for
+.IR type .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_setcancelstate (),
+.BR pthread_setcanceltype ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe
+T}
+T{
+.na
+.nh
+.BR pthread_setcancelstate (),
+.BR pthread_setcanceltype ()
+T}	Async-cancel safety	T{
+.na
+.nh
+AC-Safe
+T}
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.0
+POSIX.1-2001.
+.SH NOTES
+For details of what happens when a thread is canceled, see
+.BR \%pthread_cancel (3).
+.P
+Briefly disabling cancelability is useful
+if a thread performs some critical action
+that must not be interrupted by a cancelation request.
+Beware of disabling cancelability for long periods,
+or around operations that may block for long periods,
+since that will render the thread unresponsive to cancelation requests.
+.SS Asynchronous cancelability
+Setting the cancelability type to
+.B PTHREAD_CANCEL_ASYNCHRONOUS
+is rarely useful.
+Since the thread could be canceled at
+.I any
+time, it cannot safely reserve resources (e.g., allocating memory with
+.BR malloc (3)),
+acquire mutexes, semaphores, or locks, and so on.
+Reserving resources is unsafe because the application has no way of
+knowing what the state of these resources is when the thread is canceled;
+that is, did cancelation occur before the resources were reserved,
+while they were reserved, or after they were released?
+Furthermore, some internal data structures
+(e.g., the linked list of free blocks managed by the
+.BR malloc (3)
+family of functions) may be left in an inconsistent state
+if cancelation occurs in the middle of the function call.
+Consequently, clean-up handlers cease to be useful.
+.P
+Functions that can be safely asynchronously canceled are called
+.IR "async-cancel-safe functions" .
+POSIX.1-2001 and POSIX.1-2008 require only that
+.BR pthread_cancel (3),
+.BR pthread_setcancelstate (),
+and
+.BR pthread_setcanceltype ()
+be async-cancel-safe.
+In general, other library functions
+can't be safely called from an asynchronously cancelable thread.
+.P
+One of the few circumstances in which asynchronous cancelability is useful
+is for cancelation of a thread that is in a pure compute-bound loop.
+.SS Portability notes
+The Linux threading implementations permit the
+.I oldstate
+argument of
+.BR pthread_setcancelstate ()
+to be NULL, in which case the information about the previous
+cancelability state is not returned to the caller.
+Many other implementations also permit a NULL
+.I oldstat
+argument,
+.\" It looks like at least Solaris, FreeBSD and Tru64 support this.
+but POSIX.1 does not specify this point,
+so portable applications should always specify a non-NULL value in
+.IR oldstate .
+A precisely analogous set of statements applies for the
+.I oldtype
+argument of
+.BR pthread_setcanceltype ().
+.SH EXAMPLES
+See
+.BR pthread_cancel (3).
+.SH SEE ALSO
+.BR pthread_cancel (3),
+.BR pthread_cleanup_push (3),
+.BR pthread_testcancel (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_setcanceltype.3 b/man/man3/pthread_setcanceltype.3
new file mode 100644
index 000000000..9625bc20d
--- /dev/null
+++ b/man/man3/pthread_setcanceltype.3
@@ -0,0 +1 @@
+.so man3/pthread_setcancelstate.3
diff --git a/man/man3/pthread_setconcurrency.3 b/man/man3/pthread_setconcurrency.3
new file mode 100644
index 000000000..54a6e0ca8
--- /dev/null
+++ b/man/man3/pthread_setconcurrency.3
@@ -0,0 +1,100 @@
+'\" t
+.\" Copyright (c) 2009 Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_setconcurrency 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_setconcurrency, pthread_getconcurrency \- set/get
+the concurrency level
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_setconcurrency(int " new_level );
+.BI "int pthread_getconcurrency(" void );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_setconcurrency ()
+function informs the implementation of the application's
+desired concurrency level, specified in
+.IR new_level .
+The implementation takes this only as a hint:
+POSIX.1 does not specify the level of concurrency that
+should be provided as a result of calling
+.BR pthread_setconcurrency ().
+.P
+Specifying
+.I new_level
+as 0 instructs the implementation to manage the concurrency level
+as it deems appropriate.
+.P
+.BR pthread_getconcurrency ()
+returns the current value of the concurrency level for this process.
+.SH RETURN VALUE
+On success,
+.BR pthread_setconcurrency ()
+returns 0;
+on error, it returns a nonzero error number.
+.P
+.BR pthread_getconcurrency ()
+always succeeds, returning the concurrency level set by a previous call to
+.BR pthread_setconcurrency (),
+or 0, if
+.BR pthread_setconcurrency ()
+has not previously been called.
+.SH ERRORS
+.BR pthread_setconcurrency ()
+can fail with the following error:
+.TP
+.B EINVAL
+.I new_level
+is negative.
+.P
+POSIX.1 also documents an
+.B EAGAIN
+error ("the value specified by
+.I new_level
+would cause a system resource to be exceeded").
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_setconcurrency (),
+.BR pthread_getconcurrency ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH NOTES
+The default concurrency level is 0.
+.P
+Concurrency levels are meaningful only for M:N threading implementations,
+where at any moment a subset of a process's set of user-level threads
+may be bound to a smaller number of kernel-scheduling entities.
+Setting the concurrency level allows the application to
+give the system a hint as to the number of kernel-scheduling entities
+that should be provided for efficient execution of the application.
+.P
+Both LinuxThreads and NPTL are 1:1 threading implementations,
+so setting the concurrency level has no meaning.
+In other words,
+on Linux these functions merely exist for compatibility with other systems,
+and they have no effect on the execution of a program.
+.SH SEE ALSO
+.BR pthread_attr_setscope (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_setname_np.3 b/man/man3/pthread_setname_np.3
new file mode 100644
index 000000000..587dd3e8c
--- /dev/null
+++ b/man/man3/pthread_setname_np.3
@@ -0,0 +1,202 @@
+'\" t
+.\" Copyright (C) 2012 Chandan Apsangi <chandan.jc@gmail.com>
+.\" and Copyright (C) 2013 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_setname_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_setname_np, pthread_getname_np \- set/get the name of a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.BI "int pthread_setname_np(pthread_t " thread ", const char *" name );
+.BI "int pthread_getname_np(pthread_t " thread ", char " name [. size "], \
+size_t " size );
+.fi
+.SH DESCRIPTION
+By default, all the threads created using
+.BR pthread_create ()
+inherit the program name.
+The
+.BR pthread_setname_np ()
+function can be used to set a unique name for a thread,
+which can be useful for debugging
+multithreaded applications.
+The thread name is a meaningful C language string,
+whose length is restricted to 16 characters,
+including the terminating null byte (\[aq]\e0\[aq]).
+The
+.I thread
+argument specifies the thread whose name is to be changed;
+.I name
+specifies the new name.
+.P
+The
+.BR pthread_getname_np ()
+function can be used to retrieve the name of the thread.
+The
+.I thread
+argument specifies the thread whose name is to be retrieved.
+The buffer
+.I name
+is used to return the thread name;
+.I size
+specifies the number of bytes available in
+.IR name .
+The buffer specified by
+.I name
+should be at least 16 characters in length.
+The returned thread name in the output buffer will be null terminated.
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+.SH ERRORS
+The
+.BR pthread_setname_np ()
+function can fail with the following error:
+.TP
+.B ERANGE
+The length of the string specified pointed to by
+.I name
+exceeds the allowed limit.
+.P
+The
+.BR pthread_getname_np ()
+function can fail with the following error:
+.TP
+.B ERANGE
+The buffer specified by
+.I name
+and
+.I size
+is too small to hold the thread name.
+.P
+If either of these functions fails to open
+.IR /proc/self/task/ tid /comm ,
+then the call may fail with one of the errors described in
+.BR open (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_setname_np (),
+.BR pthread_getname_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the names.
+.SH HISTORY
+glibc 2.12.
+.SH NOTES
+.BR pthread_setname_np ()
+internally writes to the thread-specific
+.I comm
+file under the
+.I /proc
+filesystem:
+.IR /proc/self/task/ tid /comm .
+.BR pthread_getname_np ()
+retrieves it from the same location.
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR pthread_setname_np ()
+and
+.BR pthread_getname_np ().
+.P
+The following shell session shows a sample run of the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+Created a thread. Default name is: a.out
+The thread name after setting it is THREADFOO.
+\fB\[ha]Z\fP                           # Suspend the program
+[1]+  Stopped           ./a.out
+.RB "$ " "ps H \-C a.out \-o \[aq]pid tid cmd comm\[aq]"
+  PID   TID CMD                         COMMAND
+ 5990  5990 ./a.out                     a.out
+ 5990  5991 ./a.out                     THREADFOO
+.RB "$ " "cat /proc/5990/task/5990/comm"
+a.out
+.RB "$ " "cat /proc/5990/task/5991/comm"
+THREADFOO
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_setname_np.c)
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+\&
+#define NAMELEN 16
+\&
+static void *
+threadfunc(void *parm)
+{
+    sleep(5);          // allow main program to set the thread name
+    return NULL;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    pthread_t thread;
+    int rc;
+    char thread_name[NAMELEN];
+\&
+    rc = pthread_create(&thread, NULL, threadfunc, NULL);
+    if (rc != 0)
+        errc(EXIT_FAILURE, rc, "pthread_create");
+\&
+    rc = pthread_getname_np(thread, thread_name, NAMELEN);
+    if (rc != 0)
+        errc(EXIT_FAILURE, rc, "pthread_getname_np");
+\&
+    printf("Created a thread. Default name is: %s\en", thread_name);
+    rc = pthread_setname_np(thread, (argc > 1) ? argv[1] : "THREADFOO");
+    if (rc != 0)
+        errc(EXIT_FAILURE, rc, "pthread_setname_np");
+\&
+    sleep(2);
+\&
+    rc = pthread_getname_np(thread, thread_name, NAMELEN);
+    if (rc != 0)
+        errc(EXIT_FAILURE, rc, "pthread_getname_np");
+    printf("The thread name after setting it is %s.\en", thread_name);
+\&
+    rc = pthread_join(thread, NULL);
+    if (rc != 0)
+        errc(EXIT_FAILURE, rc, "pthread_join");
+\&
+    printf("Done\en");
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR prctl (2),
+.BR pthread_create (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_setschedparam.3 b/man/man3/pthread_setschedparam.3
new file mode 100644
index 000000000..0bc45ccd5
--- /dev/null
+++ b/man/man3/pthread_setschedparam.3
@@ -0,0 +1,448 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_setschedparam 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_setschedparam, pthread_getschedparam \- set/get
+scheduling policy and parameters of a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_setschedparam(pthread_t " thread ", int " policy ,
+.BI "                          const struct sched_param *" param );
+.BI "int pthread_getschedparam(pthread_t " thread ", int *restrict " policy ,
+.BI "                          struct sched_param *restrict " param );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_setschedparam ()
+function sets the scheduling policy and parameters of the thread
+.IR thread .
+.P
+.I policy
+specifies the new scheduling policy for
+.IR thread .
+The supported values for
+.IR policy ,
+and their semantics, are described in
+.BR sched (7).
+.\" FIXME . pthread_setschedparam() places no restriction on the policy,
+.\" but pthread_attr_setschedpolicy() restricts policy to RR/FIFO/OTHER
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=7013
+.P
+The structure pointed to by
+.I param
+specifies the new scheduling parameters for
+.IR thread .
+Scheduling parameters are maintained in the following structure:
+.P
+.in +4n
+.EX
+struct sched_param {
+    int sched_priority;     /* Scheduling priority */
+};
+.EE
+.in
+.P
+As can be seen, only one scheduling parameter is supported.
+For details of the permitted ranges for scheduling priorities
+in each scheduling policy, see
+.BR sched (7).
+.P
+The
+.BR pthread_getschedparam ()
+function returns the scheduling policy and parameters of the thread
+.IR thread ,
+in the buffers pointed to by
+.I policy
+and
+.IR param ,
+respectively.
+The returned priority value is that set by the most recent
+.BR pthread_setschedparam (),
+.BR pthread_setschedprio (3),
+or
+.BR pthread_create (3)
+call that affected
+.IR thread .
+The returned priority does not reflect any temporary priority adjustments
+as a result of calls to any priority inheritance or
+priority ceiling functions (see, for example,
+.BR pthread_mutexattr_setprioceiling (3)
+and
+.BR pthread_mutexattr_setprotocol (3)).
+.\" FIXME . nptl/pthread_setschedparam.c has the following
+.\"   /* If the thread should have higher priority because of some
+.\"      PTHREAD_PRIO_PROTECT mutexes it holds, adjust the priority. */
+.\" Eventually (perhaps after writing the mutexattr pages), we
+.\" may want to add something on the topic to this page.
+.SH RETURN VALUE
+On success, these functions return 0;
+on error, they return a nonzero error number.
+If
+.BR pthread_setschedparam ()
+fails, the scheduling policy and parameters of
+.I thread
+are not changed.
+.SH ERRORS
+Both of these functions can fail with the following error:
+.TP
+.B ESRCH
+No thread with the ID
+.I thread
+could be found.
+.P
+.BR pthread_setschedparam ()
+may additionally fail with the following errors:
+.TP
+.B EINVAL
+.I policy
+is not a recognized policy, or
+.I param
+does not make sense for the
+.IR policy .
+.TP
+.B EPERM
+The caller does not have appropriate privileges
+to set the specified scheduling policy and parameters.
+.P
+POSIX.1 also documents an
+.B ENOTSUP
+("attempt was made to set the policy or scheduling parameters
+to an unsupported value") error for
+.BR pthread_setschedparam ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_setschedparam (),
+.BR pthread_getschedparam ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.0
+POSIX.1-2001.
+.SH NOTES
+For a description of the permissions required to, and the effect of,
+changing a thread's scheduling policy and priority,
+and details of the permitted ranges for priorities
+in each scheduling policy, see
+.BR sched (7).
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR pthread_setschedparam ()
+and
+.BR pthread_getschedparam (),
+as well as the use of a number of other scheduling-related
+pthreads functions.
+.P
+In the following run, the main thread sets its scheduling policy to
+.B SCHED_FIFO
+with a priority of 10,
+and initializes a thread attributes object with
+a scheduling policy attribute of
+.B SCHED_RR
+and a scheduling priority attribute of 20.
+The program then sets (using
+.BR pthread_attr_setinheritsched (3))
+the inherit scheduler attribute of the thread attributes object to
+.BR PTHREAD_EXPLICIT_SCHED ,
+meaning that threads created using this attributes object should
+take their scheduling attributes from the thread attributes object.
+The program then creates a thread using the thread attributes object,
+and that thread displays its scheduling policy and priority.
+.P
+.in +4n
+.EX
+$ \fBsu\fP      # Need privilege to set real\-time scheduling policies
+Password:
+# \fB./a.out \-mf10 \-ar20 \-i e\fP
+Scheduler settings of main thread
+    policy=SCHED_FIFO, priority=10
+\&
+Scheduler settings in \[aq]attr\[aq]
+    policy=SCHED_RR, priority=20
+    inheritsched is EXPLICIT
+\&
+Scheduler attributes of new thread
+    policy=SCHED_RR, priority=20
+.EE
+.in
+.P
+In the above output, one can see that the scheduling policy and priority
+were taken from the values specified in the thread attributes object.
+.P
+The next run is the same as the previous,
+except that the inherit scheduler attribute is set to
+.BR PTHREAD_INHERIT_SCHED ,
+meaning that threads created using the thread attributes object should
+ignore the scheduling attributes specified in the attributes object
+and instead take their scheduling attributes from the creating thread.
+.P
+.in +4n
+.EX
+# \fB./a.out \-mf10 \-ar20 \-i i\fP
+Scheduler settings of main thread
+    policy=SCHED_FIFO, priority=10
+\&
+Scheduler settings in \[aq]attr\[aq]
+    policy=SCHED_RR, priority=20
+    inheritsched is INHERIT
+\&
+Scheduler attributes of new thread
+    policy=SCHED_FIFO, priority=10
+.EE
+.in
+.P
+In the above output, one can see that the scheduling policy and priority
+were taken from the creating thread,
+rather than the thread attributes object.
+.P
+Note that if we had omitted the
+.I \-i\~i
+option, the output would have been the same, since
+.B PTHREAD_INHERIT_SCHED
+is the default for the inherit scheduler attribute.
+.SS Program source
+\&
+.\" SRC BEGIN (pthreads_sched_test.c)
+.EX
+/* pthreads_sched_test.c */
+\&
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+[[noreturn]]
+static void
+usage(char *prog_name, char *msg)
+{
+    if (msg != NULL)
+        fputs(msg, stderr);
+\&
+    fprintf(stderr, "Usage: %s [options]\en", prog_name);
+    fprintf(stderr, "Options are:\en");
+#define fpe(msg) fprintf(stderr, "\et%s", msg)          /* Shorter */
+    fpe("\-a<policy><prio> Set scheduling policy and priority in\en");
+    fpe("                 thread attributes object\en");
+    fpe("                 <policy> can be\en");
+    fpe("                     f  SCHED_FIFO\en");
+    fpe("                     r  SCHED_RR\en");
+    fpe("                     o  SCHED_OTHER\en");
+    fpe("\-A               Use default thread attributes object\en");
+    fpe("\-i {e|i}         Set inherit scheduler attribute to\en");
+    fpe("                 \[aq]explicit\[aq] or \[aq]inherit\[aq]\en");
+    fpe("\-m<policy><prio> Set scheduling policy and priority on\en");
+    fpe("                 main thread before pthread_create() call\en");
+    exit(EXIT_FAILURE);
+}
+\&
+static int
+get_policy(char p, int *policy)
+{
+    switch (p) {
+    case \[aq]f\[aq]: *policy = SCHED_FIFO;     return 1;
+    case \[aq]r\[aq]: *policy = SCHED_RR;       return 1;
+    case \[aq]o\[aq]: *policy = SCHED_OTHER;    return 1;
+    default:  return 0;
+    }
+}
+\&
+static void
+display_sched_attr(int policy, const struct sched_param *param)
+{
+    printf("    policy=%s, priority=%d\en",
+           (policy == SCHED_FIFO)  ? "SCHED_FIFO" :
+           (policy == SCHED_RR)    ? "SCHED_RR" :
+           (policy == SCHED_OTHER) ? "SCHED_OTHER" :
+           "???",
+           param\->sched_priority);
+}
+\&
+static void
+display_thread_sched_attr(char *msg)
+{
+    int policy, s;
+    struct sched_param param;
+\&
+    s = pthread_getschedparam(pthread_self(), &policy, &param);
+    if (s != 0)
+        handle_error_en(s, "pthread_getschedparam");
+\&
+    printf("%s\en", msg);
+    display_sched_attr(policy, &param);
+}
+\&
+static void *
+thread_start(void *arg)
+{
+    display_thread_sched_attr("Scheduler attributes of new thread");
+\&
+    return NULL;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int s, opt, inheritsched, use_null_attrib, policy;
+    pthread_t thread;
+    pthread_attr_t attr;
+    pthread_attr_t *attrp;
+    char *attr_sched_str, *main_sched_str, *inheritsched_str;
+    struct sched_param param;
+\&
+    /* Process command\-line options. */
+\&
+    use_null_attrib = 0;
+    attr_sched_str = NULL;
+    main_sched_str = NULL;
+    inheritsched_str = NULL;
+\&
+    while ((opt = getopt(argc, argv, "a:Ai:m:")) != \-1) {
+        switch (opt) {
+        case \[aq]a\[aq]: attr_sched_str = optarg;      break;
+        case \[aq]A\[aq]: use_null_attrib = 1;          break;
+        case \[aq]i\[aq]: inheritsched_str = optarg;    break;
+        case \[aq]m\[aq]: main_sched_str = optarg;      break;
+        default:  usage(argv[0], "Unrecognized option\en");
+        }
+    }
+\&
+    if (use_null_attrib
+        && (inheritsched_str != NULL || attr_sched_str != NULL))
+    {
+        usage(argv[0], "Can\[aq]t specify \-A with \-i or \-a\en");
+    }
+\&
+    /* Optionally set scheduling attributes of main thread,
+       and display the attributes. */
+\&
+    if (main_sched_str != NULL) {
+        if (!get_policy(main_sched_str[0], &policy))
+            usage(argv[0], "Bad policy for main thread (\-m)\en");
+        param.sched_priority = strtol(&main_sched_str[1], NULL, 0);
+\&
+        s = pthread_setschedparam(pthread_self(), policy, &param);
+        if (s != 0)
+            handle_error_en(s, "pthread_setschedparam");
+    }
+\&
+    display_thread_sched_attr("Scheduler settings of main thread");
+    printf("\en");
+\&
+    /* Initialize thread attributes object according to options. */
+\&
+    attrp = NULL;
+\&
+    if (!use_null_attrib) {
+        s = pthread_attr_init(&attr);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_init");
+        attrp = &attr;
+    }
+\&
+    if (inheritsched_str != NULL) {
+        if (inheritsched_str[0] == \[aq]e\[aq])
+            inheritsched = PTHREAD_EXPLICIT_SCHED;
+        else if (inheritsched_str[0] == \[aq]i\[aq])
+            inheritsched = PTHREAD_INHERIT_SCHED;
+        else
+            usage(argv[0], "Value for \-i must be \[aq]e\[aq] or \[aq]i\[aq]\en");
+\&
+        s = pthread_attr_setinheritsched(&attr, inheritsched);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_setinheritsched");
+    }
+\&
+    if (attr_sched_str != NULL) {
+        if (!get_policy(attr_sched_str[0], &policy))
+            usage(argv[0], "Bad policy for \[aq]attr\[aq] (\-a)\en");
+        param.sched_priority = strtol(&attr_sched_str[1], NULL, 0);
+\&
+        s = pthread_attr_setschedpolicy(&attr, policy);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_setschedpolicy");
+        s = pthread_attr_setschedparam(&attr, &param);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_setschedparam");
+    }
+\&
+    /* If we initialized a thread attributes object, display
+       the scheduling attributes that were set in the object. */
+\&
+    if (attrp != NULL) {
+        s = pthread_attr_getschedparam(&attr, &param);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_getschedparam");
+        s = pthread_attr_getschedpolicy(&attr, &policy);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_getschedpolicy");
+\&
+        printf("Scheduler settings in \[aq]attr\[aq]\en");
+        display_sched_attr(policy, &param);
+\&
+        pthread_attr_getinheritsched(&attr, &inheritsched);
+        printf("    inheritsched is %s\en",
+               (inheritsched == PTHREAD_INHERIT_SCHED)  ? "INHERIT" :
+               (inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
+               "???");
+        printf("\en");
+    }
+\&
+    /* Create a thread that will display its scheduling attributes. */
+\&
+    s = pthread_create(&thread, attrp, &thread_start, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_create");
+\&
+    /* Destroy unneeded thread attributes object. */
+\&
+    if (!use_null_attrib) {
+      s = pthread_attr_destroy(&attr);
+      if (s != 0)
+          handle_error_en(s, "pthread_attr_destroy");
+    }
+\&
+    s = pthread_join(thread, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_join");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR getrlimit (2),
+.BR sched_get_priority_min (2),
+.BR pthread_attr_init (3),
+.BR pthread_attr_setinheritsched (3),
+.BR pthread_attr_setschedparam (3),
+.BR pthread_attr_setschedpolicy (3),
+.BR pthread_create (3),
+.BR pthread_self (3),
+.BR pthread_setschedprio (3),
+.BR pthreads (7),
+.BR sched (7)
diff --git a/man/man3/pthread_setschedprio.3 b/man/man3/pthread_setschedprio.3
new file mode 100644
index 000000000..8e997520e
--- /dev/null
+++ b/man/man3/pthread_setschedprio.3
@@ -0,0 +1,101 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_setschedprio 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_setschedprio \- set scheduling priority of a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_setschedprio(pthread_t " thread ", int " prio );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_setschedprio ()
+function sets the scheduling priority of the thread
+.I thread
+to the value specified in
+.IR prio .
+(By contrast
+.BR pthread_setschedparam (3)
+changes both the scheduling policy and priority of a thread.)
+.\" FIXME . nptl/pthread_setschedprio.c has the following
+.\"   /* If the thread should have higher priority because of some
+.\"      PTHREAD_PRIO_PROTECT mutexes it holds, adjust the priority. */
+.\" Eventually (perhaps after writing the mutexattr pages), we
+.\" may want to add something on the topic to this page.
+.\" nptl/pthread_setschedparam.c has a similar case.
+.SH RETURN VALUE
+On success, this function returns 0;
+on error, it returns a nonzero error number.
+If
+.BR pthread_setschedprio ()
+fails, the scheduling priority of
+.I thread
+is not changed.
+.SH ERRORS
+.TP
+.B EINVAL
+.I prio
+is not valid for the scheduling policy of the specified thread.
+.TP
+.B EPERM
+The caller does not have appropriate privileges
+to set the specified priority.
+.TP
+.B ESRCH
+No thread with the ID
+.I thread
+could be found.
+.P
+POSIX.1 also documents an
+.B ENOTSUP
+("attempt was made to set the priority
+to an unsupported value") error for
+.BR pthread_setschedparam (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_setschedprio ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.3.4.
+POSIX.1-2001.
+.SH NOTES
+For a description of the permissions required to, and the effect of,
+changing a thread's scheduling priority,
+and details of the permitted ranges for priorities
+in each scheduling policy, see
+.BR sched (7).
+.SH SEE ALSO
+.ad l
+.nh
+.BR getrlimit (2),
+.BR sched_get_priority_min (2),
+.BR pthread_attr_init (3),
+.BR pthread_attr_setinheritsched (3),
+.BR pthread_attr_setschedparam (3),
+.BR pthread_attr_setschedpolicy (3),
+.BR pthread_create (3),
+.BR pthread_self (3),
+.BR pthread_setschedparam (3),
+.BR pthreads (7),
+.BR sched (7)
diff --git a/man/man3/pthread_setspecific.3 b/man/man3/pthread_setspecific.3
new file mode 100644
index 000000000..307a94752
--- /dev/null
+++ b/man/man3/pthread_setspecific.3
@@ -0,0 +1 @@
+.so man3/pthread_key_create.3
diff --git a/man/man3/pthread_sigmask.3 b/man/man3/pthread_sigmask.3
new file mode 100644
index 000000000..8d859d760
--- /dev/null
+++ b/man/man3/pthread_sigmask.3
@@ -0,0 +1,162 @@
+'\" t
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_sigmask 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_sigmask \- examine and change mask of blocked signals
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int pthread_sigmask(int " how ", const sigset_t *" set \
+", sigset_t *" oldset );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_sigmask ():
+.nf
+    _POSIX_C_SOURCE >= 199506L || _XOPEN_SOURCE >= 500
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_sigmask ()
+function is just like
+.BR sigprocmask (2),
+with the difference that its use in multithreaded programs
+is explicitly specified by POSIX.1.
+Other differences are noted in this page.
+.P
+For a description of the arguments and operation of this function, see
+.BR sigprocmask (2).
+.SH RETURN VALUE
+On success,
+.BR pthread_sigmask ()
+returns 0;
+on error, it returns an error number.
+.SH ERRORS
+See
+.BR sigprocmask (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_sigmask ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+A new thread inherits a copy of its creator's signal mask.
+.P
+The glibc
+.BR pthread_sigmask ()
+function silently ignores attempts to block the two real-time signals that
+are used internally by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.SH EXAMPLES
+The program below blocks some signals in the main thread,
+and then creates a dedicated thread to fetch those signals via
+.BR sigwait (3).
+The following shell session demonstrates its use:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out &"
+[1] 5423
+.RB "$" " kill \-QUIT %1"
+Signal handling thread got signal 3
+.RB "$" " kill \-USR1 %1"
+Signal handling thread got signal 10
+.RB "$" " kill \-TERM %1"
+[1]+  Terminated              ./a.out
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_sigmask.c)
+.EX
+#include <errno.h>
+#include <pthread.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+/* Simple error handling functions */
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static void *
+sig_thread(void *arg)
+{
+    sigset_t *set = arg;
+    int s, sig;
+\&
+    for (;;) {
+        s = sigwait(set, &sig);
+        if (s != 0)
+            handle_error_en(s, "sigwait");
+        printf("Signal handling thread got signal %d\en", sig);
+    }
+}
+\&
+int
+main(void)
+{
+    pthread_t thread;
+    sigset_t set;
+    int s;
+\&
+    /* Block SIGQUIT and SIGUSR1; other threads created by main()
+       will inherit a copy of the signal mask. */
+\&
+    sigemptyset(&set);
+    sigaddset(&set, SIGQUIT);
+    sigaddset(&set, SIGUSR1);
+    s = pthread_sigmask(SIG_BLOCK, &set, NULL);
+    if (s != 0)
+        handle_error_en(s, "pthread_sigmask");
+\&
+    s = pthread_create(&thread, NULL, &sig_thread, &set);
+    if (s != 0)
+        handle_error_en(s, "pthread_create");
+\&
+    /* Main thread carries on to create other threads and/or do
+       other work. */
+\&
+    pause();            /* Dummy pause so we can test program */
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR sigaction (2),
+.BR sigpending (2),
+.BR sigprocmask (2),
+.BR pthread_attr_setsigmask_np (3),
+.BR pthread_create (3),
+.BR pthread_kill (3),
+.BR sigsetops (3),
+.BR pthreads (7),
+.BR signal (7)
diff --git a/man/man3/pthread_sigqueue.3 b/man/man3/pthread_sigqueue.3
new file mode 100644
index 000000000..b8a4079ce
--- /dev/null
+++ b/man/man3/pthread_sigqueue.3
@@ -0,0 +1,109 @@
+'\" t
+.\" Copyright (c) 2010 Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_sigqueue 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_sigqueue \- queue a signal and data to a thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.B #include <pthread.h>
+.P
+.BI "int pthread_sigqueue(pthread_t " thread ", int " sig ,
+.BI "                     const union sigval " value );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_sigqueue ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_sigqueue ()
+function performs a similar task to
+.BR sigqueue (3),
+but, rather than sending a signal to a process,
+it sends a signal to a thread in the same process as the
+calling thread.
+.P
+The
+.I thread
+argument is the ID of a thread in the same process as the caller.
+The
+.I sig
+argument specifies the signal to be sent.
+The
+.I value
+argument specifies data to accompany the signal; see
+.BR sigqueue (3)
+for details.
+.SH RETURN VALUE
+On success,
+.BR pthread_sigqueue ()
+returns 0;
+on error, it returns an error number.
+.SH ERRORS
+.TP
+.B EAGAIN
+The limit of signals which may be queued has been reached.
+(See
+.BR signal (7)
+for further information.)
+.TP
+.B EINVAL
+.I sig
+was invalid.
+.TP
+.B ENOSYS
+.BR pthread_sigqueue ()
+is not supported on this system.
+.TP
+.B ESRCH
+.I thread
+is not valid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_sigqueue ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The glibc implementation of
+.BR pthread_sigqueue ()
+gives an error
+.RB ( EINVAL )
+on attempts to send either of the real-time signals
+used internally by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.11.
+.SH SEE ALSO
+.BR rt_tgsigqueueinfo (2),
+.BR sigaction (2),
+.BR pthread_sigmask (3),
+.BR sigqueue (3),
+.BR sigwait (3),
+.BR pthreads (7),
+.BR signal (7)
diff --git a/man/man3/pthread_spin_destroy.3 b/man/man3/pthread_spin_destroy.3
new file mode 100644
index 000000000..f19c34516
--- /dev/null
+++ b/man/man3/pthread_spin_destroy.3
@@ -0,0 +1 @@
+.so man3/pthread_spin_init.3
diff --git a/man/man3/pthread_spin_init.3 b/man/man3/pthread_spin_init.3
new file mode 100644
index 000000000..0a72c89a0
--- /dev/null
+++ b/man/man3/pthread_spin_init.3
@@ -0,0 +1,148 @@
+.\" Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_spin_init 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_spin_init, pthread_spin_destroy \- initialize or destroy a spin lock
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_spin_init(pthread_spinlock_t *" lock ", int " pshared ");"
+.BI "int pthread_spin_destroy(pthread_spinlock_t *" lock ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_spin_init (),
+.BR pthread_spin_destroy ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.IR "General note" :
+Most programs should use mutexes
+instead of spin locks.
+Spin locks are primarily useful in conjunction with real-time
+scheduling policies.
+See NOTES.
+.P
+The
+.BR pthread_spin_init ()
+function allocates any resources required for the use of
+the spin lock referred to by
+.I lock
+and initializes the lock to be in the unlocked state.
+The
+.I pshared
+argument must have one of the following values:
+.TP
+.B PTHREAD_PROCESS_PRIVATE
+The spin lock is to be operated on only by threads in the same process
+as the thread that calls
+.BR pthread_spin_init ().
+(Attempting to share the spin lock between processes
+results in undefined behavior.)
+.TP
+.B PTHREAD_PROCESS_SHARED
+The spin lock may be operated on by any thread in any process that
+has access to the memory containing the lock
+(i.e., the lock may be in a shared memory object that is
+shared among multiple processes).
+.P
+Calling
+.BR pthread_spin_init ()
+on a spin lock that has already been initialized results
+in undefined behavior.
+.P
+The
+.BR pthread_spin_destroy ()
+function destroys a previously initialized spin lock,
+freeing any resources that were allocated for that lock.
+Destroying a spin lock that has not been previously been initialized
+or destroying a spin lock while another thread holds the lock
+results in undefined behavior.
+.P
+Once a spin lock has been destroyed,
+performing any operation on the lock other than
+once more initializing it with
+.BR pthread_spin_init ()
+results in undefined behavior.
+.P
+The result of performing operations such as
+.BR pthread_spin_lock (3),
+.BR pthread_spin_unlock (3),
+and
+.BR pthread_spin_destroy ()
+on
+.I copies
+of the object referred to by
+.I lock
+is undefined.
+.SH RETURN VALUE
+On success, there functions return zero.
+On failure, they return an error number.
+In the event that
+.BR pthread_spin_init ()
+fails, the lock is not initialized.
+.SH ERRORS
+.BR pthread_spin_init ()
+may fail with the following errors:
+.\" These errors don't occur on the glibc implementation
+.TP
+.B EAGAIN
+The system has insufficient resources to initialize
+a new spin lock.
+.TP
+.B ENOMEM
+Insufficient memory to initialize the spin lock.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.P
+Support for process-shared spin locks is a POSIX option.
+The option is supported in the glibc implementation.
+.SH NOTES
+Spin locks should be employed in conjunction with
+real-time scheduling policies
+.RB ( SCHED_FIFO ,
+or possibly
+.BR SCHED_RR ).
+Use of spin locks with nondeterministic scheduling policies such as
+.B SCHED_OTHER
+probably indicates a design mistake.
+The problem is that if a thread operating under such a policy
+is scheduled off the CPU while it holds a spin lock,
+then other threads will waste time spinning on the lock
+until the lock holder is once more rescheduled and releases the lock.
+.P
+If threads create a deadlock situation while employing spin locks,
+those threads will spin forever consuming CPU time.
+.P
+User-space spin locks are
+.I not
+applicable as a general locking solution.
+They are, by definition,
+prone to priority inversion and unbounded spin times.
+A programmer using spin locks must be exceptionally careful not
+only in the code, but also in terms of system configuration,
+thread placement, and priority assignment.
+.\" FIXME . When PTHREAD_MUTEX_ADAPTIVE_NP is one day document
+.\" make reference to it here
+.SH SEE ALSO
+.ad l
+.nh
+.BR pthread_mutex_init (3),
+.BR pthread_mutex_lock (3),
+.BR pthread_spin_lock (3),
+.BR pthread_spin_unlock (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_spin_lock.3 b/man/man3/pthread_spin_lock.3
new file mode 100644
index 000000000..bed98a9ec
--- /dev/null
+++ b/man/man3/pthread_spin_lock.3
@@ -0,0 +1,102 @@
+.\" Copyright (c) 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_spin_lock 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_spin_lock, pthread_spin_trylock, pthread_spin_unlock \-
+lock and unlock a spin lock
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_spin_lock(pthread_spinlock_t *" lock );
+.BI "int pthread_spin_trylock(pthread_spinlock_t *" lock );
+.BI "int pthread_spin_unlock(pthread_spinlock_t *" lock );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR pthread_spin_lock (),
+.BR pthread_spin_trylock ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_spin_lock ()
+function locks the spin lock referred to by
+.IR lock .
+If the spin lock is currently unlocked,
+the calling thread acquires the lock immediately.
+If the spin lock is currently locked by another thread,
+the calling thread spins, testing the lock until it becomes available,
+at which point the calling thread acquires the lock.
+.P
+Calling
+.BR pthread_spin_lock ()
+on a lock that is already held by the caller
+or a lock that has not been initialized with
+.BR pthread_spin_init (3)
+results in undefined behavior.
+.P
+The
+.BR pthread_spin_trylock ()
+function is like
+.BR pthread_spin_lock (),
+except that if the spin lock referred to by
+.I lock
+is currently locked,
+then, instead of spinning, the call returns immediately with the error
+.BR EBUSY .
+.P
+The
+.BR pthread_spin_unlock ()
+function unlocks the spin lock referred to
+.IR lock .
+If any threads are spinning on the lock,
+one of those threads will then acquire the lock.
+.P
+Calling
+.BR pthread_spin_unlock ()
+on a lock that is not held by the caller results in undefined behavior.
+.SH RETURN VALUE
+On success, these functions return zero.
+On failure, they return an error number.
+.SH ERRORS
+.BR pthread_spin_lock ()
+may fail with the following errors:
+.TP
+.B EDEADLOCK
+.\" Not detected in glibc
+The system detected a deadlock condition.
+.P
+.BR pthread_spin_trylock ()
+fails with the following errors:
+.TP
+.B EBUSY
+The spin lock is currently locked by another thread.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.SH CAVEATS
+Applying any of the functions described on this page to
+an uninitialized spin lock results in undefined behavior.
+.P
+Carefully read NOTES in
+.BR pthread_spin_init (3).
+.SH SEE ALSO
+.ad l
+.nh
+.\" FIXME . .BR pthread_mutex_lock (3),
+.BR pthread_spin_destroy (3),
+.BR pthread_spin_init (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_spin_trylock.3 b/man/man3/pthread_spin_trylock.3
new file mode 100644
index 000000000..ad2969afc
--- /dev/null
+++ b/man/man3/pthread_spin_trylock.3
@@ -0,0 +1 @@
+.so man3/pthread_spin_lock.3
diff --git a/man/man3/pthread_spin_unlock.3 b/man/man3/pthread_spin_unlock.3
new file mode 100644
index 000000000..ad2969afc
--- /dev/null
+++ b/man/man3/pthread_spin_unlock.3
@@ -0,0 +1 @@
+.so man3/pthread_spin_lock.3
diff --git a/man/man3/pthread_testcancel.3 b/man/man3/pthread_testcancel.3
new file mode 100644
index 000000000..d05462f3d
--- /dev/null
+++ b/man/man3/pthread_testcancel.3
@@ -0,0 +1,64 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_testcancel 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_testcancel \- request delivery of any pending cancelation request
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.B void pthread_testcancel(void);
+.fi
+.SH DESCRIPTION
+Calling
+.BR pthread_testcancel ()
+creates a cancelation point within the calling thread,
+so that a thread that is otherwise executing code that contains
+no cancelation points will respond to a cancelation request.
+.P
+If cancelability is disabled (using
+.BR pthread_setcancelstate (3)),
+or no cancelation request is pending,
+then a call to
+.BR pthread_testcancel ()
+has no effect.
+.SH RETURN VALUE
+This function does not return a value.
+If the calling thread is canceled as a consequence of a call
+to this function, then the function does not return.
+.SH ERRORS
+This function always succeeds.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_testcancel ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.0.
+POSIX.1-2001.
+.SH EXAMPLES
+See
+.BR pthread_cleanup_push (3).
+.SH SEE ALSO
+.BR pthread_cancel (3),
+.BR pthread_cleanup_push (3),
+.BR pthread_setcancelstate (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_timedjoin_np.3 b/man/man3/pthread_timedjoin_np.3
new file mode 100644
index 000000000..a741f46b5
--- /dev/null
+++ b/man/man3/pthread_timedjoin_np.3
@@ -0,0 +1 @@
+.so man3/pthread_tryjoin_np.3
diff --git a/man/man3/pthread_tryjoin_np.3 b/man/man3/pthread_tryjoin_np.3
new file mode 100644
index 000000000..61c3f206d
--- /dev/null
+++ b/man/man3/pthread_tryjoin_np.3
@@ -0,0 +1,154 @@
+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_tryjoin_np 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_tryjoin_np, pthread_timedjoin_np \- try to join with a
+terminated thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.BI "int pthread_tryjoin_np(pthread_t " thread ", void **" retval );
+.BI "int pthread_timedjoin_np(pthread_t " thread ", void **" retval ,
+.BI "                         const struct timespec *" abstime );
+.fi
+.SH DESCRIPTION
+These functions operate in the same way as
+.BR pthread_join (3),
+except for the differences described on this page.
+.P
+The
+.BR pthread_tryjoin_np ()
+function performs a nonblocking join with the thread
+.IR thread ,
+returning the exit status of the thread in
+.IR *retval .
+If
+.I thread
+has not yet terminated, then instead of blocking, as is done by
+.BR pthread_join (3),
+the call returns an error.
+.P
+The
+.BR pthread_timedjoin_np ()
+function performs a join-with-timeout.
+If
+.I thread
+has not yet terminated,
+then the call blocks until a maximum time, specified in
+.IR abstime ,
+measured against the
+.B CLOCK_REALTIME
+clock.
+If the timeout expires before
+.I thread
+terminates,
+the call returns an error.
+The
+.I abstime
+argument is a
+.BR timespec (3)
+structure,
+specifying an absolute time measured since the Epoch (see
+.BR time (2)).
+.SH RETURN VALUE
+On success,
+these functions return 0;
+on error, they return an error number.
+.SH ERRORS
+These functions can fail with the same errors as
+.BR pthread_join (3).
+.BR pthread_tryjoin_np ()
+can in addition fail with the following error:
+.TP
+.B EBUSY
+.I thread
+had not yet terminated at the time of the call.
+.P
+.BR pthread_timedjoin_np ()
+can in addition fail with the following errors:
+.TP
+.B EINVAL
+.I abstime
+value is invalid
+.RI ( tv_sec
+is less than 0 or
+.I tv_nsec
+is greater than 1e9).
+.TP
+.B ETIMEDOUT
+The call timed out before
+.I thread
+terminated.
+.P
+.BR pthread_timedjoin_np ()
+never returns the error
+.BR EINTR .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_tryjoin_np (),
+.BR pthread_timedjoin_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU;
+hence the suffix "_np" (nonportable) in the names.
+.SH HISTORY
+glibc 2.3.3.
+.SH BUGS
+The
+.BR pthread_timedjoin_np ()
+function measures time by internally calculating a relative sleep interval
+that is then measured against the
+.B CLOCK_MONOTONIC
+clock instead of the
+.B CLOCK_REALTIME
+clock.
+Consequently, the timeout is unaffected by discontinuous changes to the
+.B CLOCK_REALTIME
+clock.
+.SH EXAMPLES
+The following code waits to join for up to 5 seconds:
+.P
+.in +4n
+.EX
+struct timespec ts;
+int s;
+\&
+\&...
+\&
+if (clock_gettime(CLOCK_REALTIME, &ts) == \-1) {
+    /* Handle error */
+}
+\&
+ts.tv_sec += 5;
+\&
+s = pthread_timedjoin_np(thread, NULL, &ts);
+if (s != 0) {
+    /* Handle error */
+}
+.EE
+.in
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR pthread_exit (3),
+.BR pthread_join (3),
+.BR timespec (3),
+.BR pthreads (7)
diff --git a/man/man3/pthread_yield.3 b/man/man3/pthread_yield.3
new file mode 100644
index 000000000..b0a6768d8
--- /dev/null
+++ b/man/man3/pthread_yield.3
@@ -0,0 +1,78 @@
+'\" t
+.\" Copyright (c) 2009 Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_yield 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthread_yield \- yield the processor
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <pthread.h>
+.P
+.B [[deprecated]] int pthread_yield(void);
+.fi
+.SH DESCRIPTION
+.BR Note :
+This function is deprecated; see below.
+.P
+.BR pthread_yield ()
+causes the calling thread to relinquish the CPU.
+The thread is placed at the end of the run queue for its static
+priority and another thread is scheduled to run.
+For further details, see
+.BR sched_yield (2)
+.SH RETURN VALUE
+On success,
+.BR pthread_yield ()
+returns 0;
+on error, it returns an error number.
+.SH ERRORS
+On Linux, this call always succeeds
+(but portable and future-proof applications should nevertheless
+handle a possible error return).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_yield ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On Linux, this function is implemented as a call to
+.BR sched_yield (2).
+.SH STANDARDS
+None.
+.SH HISTORY
+.\" BSD, Tru64, AIX, and Irix.
+Deprecated since glibc 2.34.
+Use the standardized
+.BR sched_yield (2)
+instead.
+.SH NOTES
+.BR pthread_yield ()
+is intended for use with real-time scheduling policies (i.e.,
+.B SCHED_FIFO
+or
+.BR SCHED_RR ).
+Use of
+.BR pthread_yield ()
+with nondeterministic scheduling policies such as
+.B SCHED_OTHER
+is unspecified and very likely means your application design is broken.
+.SH SEE ALSO
+.BR sched_yield (2),
+.\" FIXME . .BR pthread_cond_wait (3),
+.BR pthreads (7),
+.BR sched (7)
diff --git a/man/man3/ptsname.3 b/man/man3/ptsname.3
new file mode 100644
index 000000000..49342d0a6
--- /dev/null
+++ b/man/man3/ptsname.3
@@ -0,0 +1,146 @@
+'\" t
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This page is in the public domain. - aeb
+.\" %%%LICENSE_END
+.\"
+.\" 2004-12-17, mtk, added description of ptsname_r() + ERRORS
+.\"
+.TH ptsname 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ptsname, ptsname_r \- get the name of the slave pseudoterminal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "char *ptsname(int " fd );
+.BI "int ptsname_r(int " fd ", char " buf [. buflen "], size_t " buflen );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ptsname ():
+.nf
+    Since glibc 2.24:
+        _XOPEN_SOURCE >= 500
+.\"        || (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+    glibc 2.23 and earlier:
+        _XOPEN_SOURCE
+.fi
+.P
+.BR ptsname_r ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR ptsname ()
+function returns the name of the slave pseudoterminal device
+corresponding to the master referred to by the file descriptor
+.IR fd .
+.P
+The
+.BR ptsname_r ()
+function is the reentrant equivalent of
+.BR ptsname ().
+It returns the name of the slave pseudoterminal device as a
+null-terminated string in the buffer pointed to by
+.IR buf .
+The
+.I buflen
+argument specifies the number of bytes available in
+.IR buf .
+.SH RETURN VALUE
+On success,
+.BR ptsname ()
+returns a pointer to a string in static storage which will be
+overwritten by subsequent calls.
+This pointer must not be freed.
+On failure, NULL is returned.
+.P
+On success,
+.BR ptsname_r ()
+returns 0.
+On failure, an error number is returned to indicate the error.
+.\" In glibc, the error number is not only returned as the return value
+.\" but also stored in errno. But this is not true for musl libc.
+.SH ERRORS
+.TP
+.B EINVAL
+.RB ( ptsname_r ()
+only)
+.I buf
+is NULL.
+(This error is returned only for
+.\" glibc commit 8f0a947cf55f3b0c4ebdf06953c57eff67a22fa9
+glibc 2.25 and earlier.)
+.TP
+.B ENOTTY
+.I fd
+does not refer to a pseudoterminal master device.
+.TP
+.B ERANGE
+.RB ( ptsname_r ()
+only)
+.I buf
+is too small.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ptsname ()
+T}	Thread safety	MT-Unsafe race:ptsname
+T{
+.na
+.nh
+.BR ptsname_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+A version of
+.BR ptsname_r ()
+is documented on Tru64 and HP-UX,
+but on those implementations,
+\-1 is returned on error, with
+.I errno
+set to indicate the error.
+Avoid using this function in portable programs.
+.SH STANDARDS
+.TP
+.BR ptsname ():
+POSIX.1-2008.
+.P
+.BR ptsname_r ()
+is a Linux extension, that is proposed for inclusion
+.\" FIXME . for later review when Issue 8 is one day released
+.\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
+.\" http://austingroupbugs.net/view.php?id=508
+in the next major revision of POSIX.1 (Issue 8).
+.SH HISTORY
+.TP
+.BR ptsname ():
+POSIX.1-2001.
+glibc 2.1.
+.P
+.BR ptsname ()
+is part of the UNIX 98 pseudoterminal support (see
+.BR pts (4)).
+.SH SEE ALSO
+.BR grantpt (3),
+.BR posix_openpt (3),
+.BR ttyname (3),
+.BR unlockpt (3),
+.BR pts (4),
+.BR pty (7)
diff --git a/man/man3/ptsname_r.3 b/man/man3/ptsname_r.3
new file mode 100644
index 000000000..0a5f98d4e
--- /dev/null
+++ b/man/man3/ptsname_r.3
@@ -0,0 +1 @@
+.so man3/ptsname.3
diff --git a/man/man3/putc.3 b/man/man3/putc.3
new file mode 100644
index 000000000..a7c3b57fc
--- /dev/null
+++ b/man/man3/putc.3
@@ -0,0 +1 @@
+.so man3/puts.3
diff --git a/man/man3/putc_unlocked.3 b/man/man3/putc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/putc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/putchar.3 b/man/man3/putchar.3
new file mode 100644
index 000000000..a7c3b57fc
--- /dev/null
+++ b/man/man3/putchar.3
@@ -0,0 +1 @@
+.so man3/puts.3
diff --git a/man/man3/putchar_unlocked.3 b/man/man3/putchar_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/putchar_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/putenv.3 b/man/man3/putenv.3
new file mode 100644
index 000000000..d0892b420
--- /dev/null
+++ b/man/man3/putenv.3
@@ -0,0 +1,141 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"	Single UNIX Specification, Version 2
+.\" Modified Thu Apr  8 15:00:12 1993, David Metcalfe
+.\" Modified Sat Jul 24 18:44:45 1993, Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Feb 14 21:47:50 1997 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Mon Oct 11 11:11:11 1999 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Wed Nov 10 00:02:26 1999 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Sun May 20 22:17:20 2001 by Andries Brouwer (aeb@cwi.nl)
+.TH putenv 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+putenv \- change or add an environment variable
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int putenv(char *" string );
+.\" Not: const char *
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR putenv ():
+.nf
+    _XOPEN_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR putenv ()
+function adds or changes the value of environment
+variables.
+The argument \fIstring\fP is of the form \fIname\fP=\fIvalue\fP.
+If \fIname\fP does not already exist in the environment, then
+\fIstring\fP is added to the environment.
+If \fIname\fP does exist,
+then the value of \fIname\fP in the environment is changed to
+\fIvalue\fP.
+The string pointed to by \fIstring\fP becomes part of the environment,
+so altering the string changes the environment.
+.SH RETURN VALUE
+The
+.BR putenv ()
+function returns zero on success.
+On failure, it returns a nonzero value, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient space to allocate new environment.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR putenv ()
+T}	Thread safety	MT-Unsafe const:env
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr2, 4.3BSD-Reno.
+.P
+The
+.BR putenv ()
+function is not required to be reentrant, and the
+one in glibc 2.0 is not, but the glibc 2.1 version is.
+.\" .P
+.\" Description for libc4, libc5, glibc:
+.\" If the argument \fIstring\fP is of the form \fIname\fP,
+.\" and does not contain an \[aq]=\[aq] character, then the variable \fIname\fP
+.\" is removed from the environment.
+.\" If
+.\" .BR putenv ()
+.\" has to allocate a new array \fIenviron\fP,
+.\" and the previous array was also allocated by
+.\" .BR putenv (),
+.\" then it will be freed.
+.\" In no case will the old storage associated
+.\" to the environment variable itself be freed.
+.P
+Since glibc 2.1.2, the glibc implementation conforms to SUSv2:
+the pointer \fIstring\fP given to
+.BR putenv ()
+is used.
+In particular, this string becomes part of the environment;
+changing it later will change the environment.
+(Thus, it is an error to call
+.BR putenv ()
+with an automatic variable
+as the argument, then return from the calling function while \fIstring\fP
+is still part of the environment.)
+However, from glibc 2.0 to glibc 2.1.1, it differs:
+a copy of the string is used.
+On the one hand this causes a memory leak, and on the other hand
+it violates SUSv2.
+.P
+The 4.3BSD-Reno version, like glibc 2.0, uses a copy;
+this is fixed in all modern BSDs.
+.P
+SUSv2 removes the \fIconst\fP from the prototype, and so does glibc 2.1.3.
+.P
+The GNU C library implementation provides a nonstandard extension.
+If
+.I string
+does not include an equal sign:
+.P
+.in +4n
+.EX
+putenv("NAME");
+.EE
+.in
+.P
+then the named variable is removed from the caller's environment.
+.SH SEE ALSO
+.BR clearenv (3),
+.BR getenv (3),
+.BR setenv (3),
+.BR unsetenv (3),
+.BR environ (7)
diff --git a/man/man3/putgrent.3 b/man/man3/putgrent.3
new file mode 100644
index 000000000..2df85eca0
--- /dev/null
+++ b/man/man3/putgrent.3
@@ -0,0 +1,66 @@
+'\" t
+.\" Copyright 2003 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH putgrent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+putgrent \- write a group database entry to a file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <grp.h>
+.P
+.BI "int putgrent(const struct group *restrict " grp \
+", FILE *restrict " stream );
+.fi
+.SH DESCRIPTION
+The
+.BR putgrent ()
+function is the counterpart for
+.BR fgetgrent (3).
+The function writes the content of the provided
+.I struct group
+into the
+.IR stream .
+The list of group members must be NULL-terminated or NULL-initialized.
+.P
+The
+.I struct group
+is defined as follows:
+.P
+.in +4n
+.EX
+struct group {
+    char   *gr_name;      /* group name */
+    char   *gr_passwd;    /* group password */
+    gid_t   gr_gid;       /* group ID */
+    char  **gr_mem;       /* group members */
+};
+.EE
+.in
+.SH RETURN VALUE
+The function returns zero on success, and a nonzero value on error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR putgrent ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR fgetgrent (3),
+.BR getgrent (3),
+.BR group (5)
diff --git a/man/man3/putpwent.3 b/man/man3/putpwent.3
new file mode 100644
index 000000000..a84bfce93
--- /dev/null
+++ b/man/man3/putpwent.3
@@ -0,0 +1,96 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:43:46 1993 by Rik Faith (faith@cs.unc.edu)
+.TH putpwent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+putpwent \- write a password file entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <sys/types.h>
+.B #include <pwd.h>
+.P
+.BI "int putpwent(const struct passwd *restrict " p \
+", FILE *restrict " stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR putpwent ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR putpwent ()
+function writes a password entry from the
+structure \fIp\fP in the file associated with \fIstream\fP.
+.P
+The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows:
+.P
+.in +4n
+.EX
+struct passwd {
+    char    *pw_name;        /* username */
+    char    *pw_passwd;      /* user password */
+    uid_t    pw_uid;         /* user ID */
+    gid_t    pw_gid;         /* group ID */
+    char    *pw_gecos;       /* real name */
+    char    *pw_dir;         /* home directory */
+    char    *pw_shell;       /* shell program */
+};
+.EE
+.in
+.SH RETURN VALUE
+The
+.BR putpwent ()
+function returns 0 on success.
+On failure, it returns \-1, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+Invalid (NULL) argument given.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR putpwent ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4.
+.SH SEE ALSO
+.BR endpwent (3),
+.BR fgetpwent (3),
+.BR getpw (3),
+.BR getpwent (3),
+.BR getpwnam (3),
+.BR getpwuid (3),
+.BR setpwent (3)
diff --git a/man/man3/puts.3 b/man/man3/puts.3
new file mode 100644
index 000000000..19241af90
--- /dev/null
+++ b/man/man3/puts.3
@@ -0,0 +1,124 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 18:42:59 1993 by Rik Faith (faith@cs.unc.edu)
+.TH puts 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fputc, fputs, putc, putchar, puts \- output of characters and strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int fputc(int " c ", FILE *" stream );
+.BI "int putc(int " c ", FILE *" stream );
+.BI "int putchar(int " c );
+.P
+.BI "int fputs(const char *restrict " s ", FILE *restrict " stream );
+.BI "int puts(const char *" s );
+.fi
+.SH DESCRIPTION
+.BR fputc ()
+writes the character
+.IR c ,
+cast to an
+.IR "unsigned char" ,
+to
+.IR stream .
+.P
+.BR putc ()
+is equivalent to
+.BR fputc ()
+except that it may be implemented as a macro which evaluates
+.I stream
+more than once.
+.P
+.BI "putchar(" c )
+is equivalent to
+.BI "putc(" c ", " stdout ) \fR.
+.P
+.BR fputs ()
+writes the string
+.I s
+to
+.IR stream ,
+without its terminating null byte (\[aq]\e0\[aq]).
+.P
+.BR puts ()
+writes the string
+.I s
+and a trailing newline
+to
+.IR stdout .
+.P
+Calls to the functions described here can be mixed with each other and with
+calls to other output functions from the
+.I stdio
+library for the same output stream.
+.P
+For nonlocking counterparts, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+.BR fputc (),
+.BR putc (),
+and
+.BR putchar ()
+return the character written as an
+.I unsigned char
+cast to an
+.I int
+or
+.B EOF
+on error.
+.P
+.BR puts ()
+and
+.BR fputs ()
+return a nonnegative number on success, or
+.B EOF
+on error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR fputc (),
+.BR fputs (),
+.BR putc (),
+.BR putchar (),
+.BR puts ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, C99.
+.SH BUGS
+It is not advisable to mix calls to output functions from the
+.I stdio
+library with low-level calls to
+.BR write (2)
+for the file descriptor associated with the same output stream; the results
+will be undefined and very probably not what you want.
+.SH SEE ALSO
+.BR write (2),
+.BR ferror (3),
+.BR fgets (3),
+.BR fopen (3),
+.BR fputwc (3),
+.BR fputws (3),
+.BR fseek (3),
+.BR fwrite (3),
+.BR putwchar (3),
+.BR scanf (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/putspent.3 b/man/man3/putspent.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/putspent.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/pututline.3 b/man/man3/pututline.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/pututline.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/pututxline.3 b/man/man3/pututxline.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/pututxline.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/putw.3 b/man/man3/putw.3
new file mode 100644
index 000000000..750934559
--- /dev/null
+++ b/man/man3/putw.3
@@ -0,0 +1 @@
+.so man3/getw.3
diff --git a/man/man3/putwc.3 b/man/man3/putwc.3
new file mode 100644
index 000000000..81826be5d
--- /dev/null
+++ b/man/man3/putwc.3
@@ -0,0 +1 @@
+.so man3/fputwc.3
diff --git a/man/man3/putwc_unlocked.3 b/man/man3/putwc_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/putwc_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/putwchar.3 b/man/man3/putwchar.3
new file mode 100644
index 000000000..5b48fd439
--- /dev/null
+++ b/man/man3/putwchar.3
@@ -0,0 +1,92 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification
+.\"      http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH putwchar 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+putwchar \- write a wide character to standard output
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wint_t putwchar(wchar_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR putwchar ()
+function is the wide-character equivalent of the
+.BR putchar (3)
+function.
+It writes the wide character
+.I wc
+to
+.IR stdout .
+If
+.I ferror(stdout)
+becomes true, it returns
+.BR WEOF .
+If a wide character
+conversion error occurs, it sets
+.I errno
+to
+.B EILSEQ
+and returns
+.BR WEOF .
+Otherwise, it returns
+.IR wc .
+.P
+For a nonlocking counterpart, see
+.BR unlocked_stdio (3).
+.SH RETURN VALUE
+The
+.BR putwchar ()
+function returns
+.I wc
+if no error occurred, or
+.B WEOF
+to indicate an error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR putwchar ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR putwchar ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+It is reasonable to expect that
+.BR putwchar ()
+will actually write
+the multibyte sequence corresponding to the wide character
+.IR wc .
+.SH SEE ALSO
+.BR fputwc (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/putwchar_unlocked.3 b/man/man3/putwchar_unlocked.3
new file mode 100644
index 000000000..858bd0849
--- /dev/null
+++ b/man/man3/putwchar_unlocked.3
@@ -0,0 +1 @@
+.so man3/unlocked_stdio.3
diff --git a/man/man3/pvalloc.3 b/man/man3/pvalloc.3
new file mode 100644
index 000000000..791d4c801
--- /dev/null
+++ b/man/man3/pvalloc.3
@@ -0,0 +1 @@
+.so man3/posix_memalign.3
diff --git a/man/man3/qecvt.3 b/man/man3/qecvt.3
new file mode 100644
index 000000000..dda5eb92a
--- /dev/null
+++ b/man/man3/qecvt.3
@@ -0,0 +1,110 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" This replaces an earlier man page written by Walter Harms
+.\" <walter.harms@informatik.uni-oldenburg.de>.
+.\"
+.TH qecvt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+qecvt, qfcvt, qgcvt \- convert a floating-point number to a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "[[deprecated]] char *qecvt(long double " number ", int " ndigits ,
+.BI "                           int *restrict " decpt ", int *restrict " sign );
+.BI "[[deprecated]] char *qfcvt(long double " number ", int " ndigits ,
+.BI "                           int *restrict " decpt ", int *restrict " sign );
+.BI "[[deprecated]] char *qgcvt(long double " number ", int " ndigit ", char *" buf );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR qecvt (),
+.BR qfcvt (),
+.BR qgcvt ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    In glibc up to and including 2.19:
+        _SVID_SOURCE
+.fi
+.\" FIXME . The full FTM picture looks to have been something like the
+.\" following mess:
+.\"    glibc 2.20 onward
+.\"        _DEFAULT_SOURCE
+.\"    glibc 2.18 to glibc 2.19
+.\"        _BSD_SOURCE || _SVID_SOURCE
+.\"    glibc 2.10 to glibc 2.17
+.\"        _SVID_SOURCE || (_XOPEN_SOURCE >= 500 ||
+.\"            (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
+.\"                ! (_POSIX_C_SOURCE >= 200809L))
+.\"    Before glibc 2.10:
+.\"        _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
+.\"            (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+.SH DESCRIPTION
+The functions
+.BR qecvt (),
+.BR qfcvt (),
+and
+.BR qgcvt ()
+are identical to
+.BR ecvt (3),
+.BR fcvt (3),
+and
+.BR gcvt (3)
+respectively, except that they use a
+.I "long double"
+argument
+.IR number .
+See
+.BR ecvt (3)
+and
+.BR gcvt (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR qecvt ()
+T}	Thread safety	MT-Unsafe race:qecvt
+T{
+.na
+.nh
+.BR qfcvt ()
+T}	Thread safety	MT-Unsafe race:qfcvt
+T{
+.na
+.nh
+.BR qgcvt ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+SVr4, SunOS, GNU.
+.\" Not supported by libc4 and libc5.
+.P
+These functions are obsolete.
+Instead,
+.BR snprintf (3)
+is recommended.
+.SH SEE ALSO
+.BR ecvt (3),
+.BR ecvt_r (3),
+.BR gcvt (3),
+.BR sprintf (3)
diff --git a/man/man3/qecvt_r.3 b/man/man3/qecvt_r.3
new file mode 100644
index 000000000..41ce9ee8a
--- /dev/null
+++ b/man/man3/qecvt_r.3
@@ -0,0 +1 @@
+.so man3/ecvt_r.3
diff --git a/man/man3/qfcvt.3 b/man/man3/qfcvt.3
new file mode 100644
index 000000000..7e583109e
--- /dev/null
+++ b/man/man3/qfcvt.3
@@ -0,0 +1 @@
+.so man3/qecvt.3
diff --git a/man/man3/qfcvt_r.3 b/man/man3/qfcvt_r.3
new file mode 100644
index 000000000..41ce9ee8a
--- /dev/null
+++ b/man/man3/qfcvt_r.3
@@ -0,0 +1 @@
+.so man3/ecvt_r.3
diff --git a/man/man3/qgcvt.3 b/man/man3/qgcvt.3
new file mode 100644
index 000000000..7e583109e
--- /dev/null
+++ b/man/man3/qgcvt.3
@@ -0,0 +1 @@
+.so man3/qecvt.3
diff --git a/man/man3/qsort.3 b/man/man3/qsort.3
new file mode 100644
index 000000000..16e8b1b65
--- /dev/null
+++ b/man/man3/qsort.3
@@ -0,0 +1,157 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified 1993-03-29, David Metcalfe
+.\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
+.\" 2006-01-15, mtk, Added example program.
+.\" Modified 2012-03-08, Mark R. Bannister <cambridge@users.sourceforge.net>
+.\"                  and Ben Bacarisse <software@bsb.me.uk>
+.\"     Document qsort_r()
+.\"
+.TH qsort 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+qsort, qsort_r \- sort an array
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "void qsort(void " base [. size " * ." nmemb "], size_t " nmemb ", \
+size_t " size ,
+.BI "           int (*" compar ")(const void [." size "], \
+const void [." size ]));
+.BI "void qsort_r(void " base [. size " * ." nmemb "], size_t " nmemb ", \
+size_t " size ,
+.BI "           int (*" compar ")(const void [." size "], \
+const void [." size "], void *),"
+.BI "           void *" arg ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR qsort_r ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR qsort ()
+function sorts an array with \fInmemb\fP elements of
+size \fIsize\fP.
+The \fIbase\fP argument points to the start of the
+array.
+.P
+The contents of the array are sorted in ascending order according to a
+comparison function pointed to by \fIcompar\fP, which is called with two
+arguments that point to the objects being compared.
+.P
+The comparison function must return an integer less than, equal to, or
+greater than zero if the first argument is considered to be respectively
+less than, equal to, or greater than the second.
+If two members compare as equal,
+their order in the sorted array is undefined.
+.P
+The
+.BR qsort_r ()
+function is identical to
+.BR qsort ()
+except that the comparison function
+.I compar
+takes a third argument.
+A pointer is passed to the comparison function via
+.IR arg .
+In this way, the comparison function does not need to use global variables to
+pass through arbitrary arguments, and is therefore reentrant and safe to
+use in threads.
+.SH RETURN VALUE
+The
+.BR qsort ()
+and
+.BR qsort_r ()
+functions return no value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR qsort (),
+.BR qsort_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR qsort ()
+C11, POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR qsort ()
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.TP
+.BR qsort_r ()
+glibc 2.8.
+.SH NOTES
+To compare C strings, the comparison function can call
+.BR strcmp (3),
+as shown in the example below.
+.SH EXAMPLES
+For one example of use, see the example under
+.BR bsearch (3).
+.P
+Another example is the following program,
+which sorts the strings given in its command-line arguments:
+.P
+.\" SRC BEGIN (qsort.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+static int
+cmpstringp(const void *p1, const void *p2)
+{
+    /* The actual arguments to this function are "pointers to
+       pointers to char", but strcmp(3) arguments are "pointers
+       to char", hence the following cast plus dereference. */
+\&
+    return strcmp(*(const char **) p1, *(const char **) p2);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <string>...\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    qsort(&argv[1], argc \- 1, sizeof(char *), cmpstringp);
+\&
+    for (size_t j = 1; j < argc; j++)
+        puts(argv[j]);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR sort (1),
+.BR alphasort (3),
+.BR strcmp (3),
+.BR versionsort (3)
diff --git a/man/man3/qsort_r.3 b/man/man3/qsort_r.3
new file mode 100644
index 000000000..d073335b4
--- /dev/null
+++ b/man/man3/qsort_r.3
@@ -0,0 +1 @@
+.so man3/qsort.3
diff --git a/man/man3/queue.3 b/man/man3/queue.3
new file mode 100644
index 000000000..000e4b150
--- /dev/null
+++ b/man/man3/queue.3
@@ -0,0 +1 @@
+.so man7/queue.7
diff --git a/man/man3/raise.3 b/man/man3/raise.3
new file mode 100644
index 000000000..b412e52bd
--- /dev/null
+++ b/man/man3/raise.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 18:40:56 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995 by Mike Battersby (mib@deakin.edu.au)
+.\"
+.TH raise 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+raise \- send a signal to the caller
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int raise(int " sig );
+.fi
+.SH DESCRIPTION
+The
+.BR raise ()
+function sends a signal to the calling process or thread.
+In a single-threaded program it is equivalent to
+.P
+.in +4n
+.EX
+kill(getpid(), sig);
+.EE
+.in
+.P
+In a multithreaded program it is equivalent to
+.P
+.in +4n
+.EX
+pthread_kill(pthread_self(), sig);
+.EE
+.in
+.P
+If the signal causes a handler to be called,
+.BR raise ()
+will return only after the signal handler has returned.
+.SH RETURN VALUE
+.BR raise ()
+returns 0 on success, and nonzero for failure.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR raise ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89.
+.P
+Since glibc 2.3.3,
+.BR raise ()
+is implemented by calling
+.BR tgkill (2),
+.\" 2.3.2 used the obsolete tkill(), if available.
+if the kernel supports that system call.
+Older glibc versions implemented
+.BR raise ()
+using
+.BR kill (2).
+.SH SEE ALSO
+.BR getpid (2),
+.BR kill (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR pthread_kill (3),
+.BR signal (7)
diff --git a/man/man3/rand.3 b/man/man3/rand.3
new file mode 100644
index 000000000..9f63ee9a1
--- /dev/null
+++ b/man/man3/rand.3
@@ -0,0 +1,240 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified 1993-03-29, David Metcalfe
+.\" Modified 1993-04-28, Lars Wirzenius
+.\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-05-18, Rik Faith (faith@cs.unc.edu) to add
+.\"          better discussion of problems with rand on other systems.
+.\"          (Thanks to Esa Hyyti{ (ehyytia@snakemail.hut.fi).)
+.\" Modified 1998-04-10, Nicolás Lichtmaier <nick@debian.org>
+.\"          with contribution from Francesco Potorti <F.Potorti@cnuce.cnr.it>
+.\" Modified 2003-11-15, aeb, added rand_r
+.\" 2010-09-13, mtk, added example program
+.\"
+.TH rand 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rand, rand_r, srand \- pseudo-random number generator
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.B int rand(void);
+.BI "void srand(unsigned int " seed );
+.P
+.BI "[[deprecated]] int rand_r(unsigned int *" seedp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR rand_r ():
+.nf
+    Since glibc 2.24:
+        _POSIX_C_SOURCE >= 199506L
+    glibc 2.23 and earlier
+        _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR rand ()
+function returns a pseudo-random integer in the range 0 to
+.B RAND_MAX
+inclusive (i.e., the mathematical range [0,\ \fBRAND_MAX\fR]).
+.P
+The
+.BR srand ()
+function sets its argument as the seed for a new
+sequence of pseudo-random integers to be returned by
+.BR rand ().
+These sequences are repeatable by calling
+.BR srand ()
+with the same seed value.
+.P
+If no seed value is provided, the
+.BR rand ()
+function is automatically seeded with a value of 1.
+.P
+The function
+.BR rand ()
+is not reentrant, since it
+uses hidden state that is modified on each call.
+This might just be the seed value to be used by the next call,
+or it might be something more elaborate.
+In order to get reproducible behavior in a threaded
+application, this state must be made explicit;
+this can be done using the reentrant function
+.BR rand_r ().
+.P
+Like
+.BR rand (),
+.BR rand_r ()
+returns a pseudo-random integer in the range [0,\ \fBRAND_MAX\fR].
+The
+.I seedp
+argument is a pointer to an
+.I unsigned int
+that is used to store state between calls.
+If
+.BR rand_r ()
+is called with the same initial value for the integer pointed to by
+.IR seedp ,
+and that value is not modified between calls,
+then the same pseudo-random sequence will result.
+.P
+The value pointed to by the
+.I seedp
+argument of
+.BR rand_r ()
+provides only a very small amount of state,
+so this function will be a weak pseudo-random generator.
+Try
+.BR drand48_r (3)
+instead.
+.SH RETURN VALUE
+The
+.BR rand ()
+and
+.BR rand_r ()
+functions return a value between 0 and
+.B RAND_MAX
+(inclusive).
+The
+.BR srand ()
+function returns no value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR rand (),
+.BR rand_r (),
+.BR srand ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The versions of
+.BR rand ()
+and
+.BR srand ()
+in the Linux C Library use the same random number generator as
+.BR random (3)
+and
+.BR srandom (3),
+so the lower-order bits should be as random as the higher-order bits.
+However, on older
+.BR rand ()
+implementations, and on current implementations on different systems,
+the lower-order bits are much less random than the higher-order bits.
+Do not use this function in applications intended to be portable
+when good randomness is needed.
+(Use
+.BR random (3)
+instead.)
+.SH STANDARDS
+.TP
+.BR rand ()
+.TQ
+.BR srand ()
+C11, POSIX.1-2008.
+.TP
+.BR rand_r ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR rand ()
+.TQ
+.BR srand ()
+SVr4, 4.3BSD, C89, POSIX.1-2001.
+.TP
+.BR rand_r ()
+POSIX.1-2001.
+Obsolete in POSIX.1-2008.
+.SH EXAMPLES
+POSIX.1-2001 gives the following example of an implementation of
+.BR rand ()
+and
+.BR srand (),
+possibly useful when one needs the same sequence on two different machines.
+.P
+.in +4n
+.EX
+static unsigned long next = 1;
+\&
+/* RAND_MAX assumed to be 32767 */
+int myrand(void) {
+    next = next * 1103515245 + 12345;
+    return((unsigned)(next/65536) % 32768);
+}
+\&
+void mysrand(unsigned int seed) {
+    next = seed;
+}
+.EE
+.in
+.P
+The following program can be used to display the
+pseudo-random sequence produced by
+.BR rand ()
+when given a particular seed.
+When the seed is
+.IR \-1 ,
+the program uses a random seed.
+.P
+.in +4n
+.\" SRC BEGIN (rand.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int           r;
+    unsigned int  seed, nloops;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <seed> <nloops>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    seed = atoi(argv[1]);
+    nloops = atoi(argv[2]);
+\&
+    if (seed == \-1) {
+        seed = arc4random();
+        printf("seed: %u\en", seed);
+    }
+\&
+    srand(seed);
+    for (unsigned int j = 0; j < nloops; j++) {
+        r =  rand();
+        printf("%d\en", r);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR drand48 (3),
+.BR random (3)
diff --git a/man/man3/rand_r.3 b/man/man3/rand_r.3
new file mode 100644
index 000000000..b007c2fc2
--- /dev/null
+++ b/man/man3/rand_r.3
@@ -0,0 +1 @@
+.so man3/rand.3
diff --git a/man/man3/random.3 b/man/man3/random.3
new file mode 100644
index 000000000..c6dc573dd
--- /dev/null
+++ b/man/man3/random.3
@@ -0,0 +1,193 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Mar 28 00:25:51 1993, David Metcalfe
+.\" Modified Sat Jul 24 18:13:39 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Aug 20 21:47:07 2000, aeb
+.\"
+.TH random 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+random, srandom, initstate, setstate \- random number generator
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.B long random(void);
+.BI "void srandom(unsigned int " seed );
+.P
+.BI "char *initstate(unsigned int " seed ", char " state [. n "], size_t " n );
+.BI "char *setstate(char *" state );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR random (),
+.BR srandom (),
+.BR initstate (),
+.BR setstate ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR random ()
+function uses a nonlinear additive feedback random
+number generator employing a default table of size 31 long integers to
+return successive pseudo-random numbers in
+the range from 0 to 2\[ha]31\ \-\ 1.
+The period of this random number generator is very large, approximately
+.IR "16\ *\ ((2\[ha]31)\ \-\ 1)" .
+.P
+The
+.BR srandom ()
+function sets its argument as the seed for a new
+sequence of pseudo-random integers to be returned by
+.BR random ().
+These sequences are repeatable by calling
+.BR srandom ()
+with the same
+seed value.
+If no seed value is provided, the
+.BR random ()
+function
+is automatically seeded with a value of 1.
+.P
+The
+.BR initstate ()
+function allows a state array \fIstate\fP to
+be initialized for use by
+.BR random ().
+The size of the state array
+\fIn\fP is used by
+.BR initstate ()
+to decide how sophisticated a
+random number generator it should use\[em]the larger the state array,
+the better the random numbers will be.
+Current "optimal" values for the size of the state array \fIn\fP are
+8, 32, 64, 128, and 256 bytes; other amounts will be rounded down to
+the nearest known amount.
+Using less than 8 bytes results in an error.
+\fIseed\fP is the seed for the
+initialization, which specifies a starting point for the random number
+sequence, and provides for restarting at the same point.
+.P
+The
+.BR setstate ()
+function changes the state array used by the
+.BR random ()
+function.
+The state array \fIstate\fP is used for
+random number generation until the next call to
+.BR initstate ()
+or
+.BR setstate ().
+\fIstate\fP must first have been initialized
+using
+.BR initstate ()
+or be the result of a previous call of
+.BR setstate ().
+.SH RETURN VALUE
+The
+.BR random ()
+function returns a value between 0 and
+.IR "(2\[ha]31)\ \-\ 1" .
+The
+.BR srandom ()
+function returns no value.
+.P
+The
+.BR initstate ()
+function returns a pointer to the previous state array.
+On failure, it returns NULL, and
+.I errno
+is set to indicate the error.
+.P
+On success,
+.BR setstate ()
+returns a pointer to the previous state array.
+On failure, it returns NULL, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The
+.I state
+argument given to
+.BR setstate ()
+was NULL.
+.TP
+.B EINVAL
+A state array of less than 8 bytes was specified to
+.BR initstate ().
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR random (),
+.BR srandom (),
+.BR initstate (),
+.BR setstate ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.SH NOTES
+Random-number generation is a complex topic.
+.I Numerical Recipes in C: The Art of Scientific Computing
+(William H.\& Press, Brian P.\& Flannery, Saul A.\& Teukolsky,
+William T.\& Vetterling; New York: Cambridge University Press, 2007, 3rd ed.)
+provides an excellent discussion of practical random-number generation
+issues in Chapter 7 (Random Numbers).
+.P
+For a more theoretical discussion which also covers many practical issues
+in depth, see Chapter 3 (Random Numbers) in Donald E.\& Knuth's
+.IR "The Art of Computer Programming" ,
+volume 2 (Seminumerical Algorithms), 2nd ed.; Reading, Massachusetts:
+Addison-Wesley Publishing Company, 1981.
+.SH CAVEATS
+The
+.BR random ()
+function should not be used in multithreaded programs
+where reproducible behavior is required.
+Use
+.BR random_r (3)
+for that purpose.
+.SH BUGS
+According to POSIX,
+.BR initstate ()
+should return NULL on error.
+In the glibc implementation,
+.I errno
+is (as specified) set on error, but the function does not return NULL.
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=15380
+.SH SEE ALSO
+.BR getrandom (2),
+.BR drand48 (3),
+.BR rand (3),
+.BR random_r (3),
+.BR srand (3)
diff --git a/man/man3/random_r.3 b/man/man3/random_r.3
new file mode 100644
index 000000000..0dbba5c84
--- /dev/null
+++ b/man/man3/random_r.3
@@ -0,0 +1,176 @@
+'\" t
+.\" Copyright 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH random_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+random_r, srandom_r, initstate_r, setstate_r \- reentrant
+random number generator
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int random_r(struct random_data *restrict " buf ,
+.BI "             int32_t *restrict " result );
+.BI "int srandom_r(unsigned int " seed ", struct random_data *" buf );
+.P
+.BI "int initstate_r(unsigned int " seed ", \
+char " statebuf "[restrict ." statelen ],
+.BI "             size_t " statelen ", struct random_data *restrict " buf );
+.BI "int setstate_r(char *restrict " statebuf ,
+.BI "             struct random_data *restrict " buf );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR random_r (),
+.BR srandom_r (),
+.BR initstate_r (),
+.BR setstate_r ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+These functions are the reentrant equivalents
+of the functions described in
+.BR random (3).
+They are suitable for use in multithreaded programs where each thread
+needs to obtain an independent, reproducible sequence of random numbers.
+.P
+The
+.BR random_r ()
+function is like
+.BR random (3),
+except that instead of using state information maintained
+in a global variable,
+it uses the state information in the argument pointed to by
+.IR buf ,
+which must have been previously initialized by
+.BR initstate_r ().
+The generated random number is returned in the argument
+.IR result .
+.P
+The
+.BR srandom_r ()
+function is like
+.BR srandom (3),
+except that it initializes the seed for the random number generator
+whose state is maintained in the object pointed to by
+.IR buf ,
+which must have been previously initialized by
+.BR initstate_r (),
+instead of the seed associated with the global state variable.
+.P
+The
+.BR initstate_r ()
+function is like
+.BR initstate (3)
+except that it initializes the state in the object pointed to by
+.IR buf ,
+rather than initializing the global state variable.
+Before calling this function, the
+.I buf.state
+field must be initialized to NULL.
+The
+.BR initstate_r ()
+function records a pointer to the
+.I statebuf
+argument inside the structure pointed to by
+.IR buf .
+Thus,
+.I statebuf
+should not be deallocated so long as
+.I buf
+is still in use.
+(So,
+.I statebuf
+should typically be allocated as a static variable,
+or allocated on the heap using
+.BR malloc (3)
+or similar.)
+.P
+The
+.BR setstate_r ()
+function is like
+.BR setstate (3)
+except that it modifies the state in the object pointed to by
+.IR buf ,
+rather than modifying the global state variable.
+\fIstate\fP must first have been initialized
+using
+.BR initstate_r ()
+or be the result of a previous call of
+.BR setstate_r ().
+.SH RETURN VALUE
+All of these functions return 0 on success.
+On error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+A state array of less than 8 bytes was specified to
+.BR initstate_r ().
+.TP
+.B EINVAL
+The
+.I statebuf
+or
+.I buf
+argument to
+.BR setstate_r ()
+was NULL.
+.TP
+.B EINVAL
+The
+.I buf
+or
+.I result
+argument to
+.BR random_r ()
+was NULL.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR random_r (),
+.BR srandom_r (),
+.BR initstate_r (),
+.BR setstate_r ()
+T}	Thread safety	MT-Safe race:buf
+.TE
+.SH STANDARDS
+GNU.
+.\" These functions appear to be on Tru64, but don't seem to be on
+.\" Solaris, HP-UX, or FreeBSD.
+.SH BUGS
+The
+.BR initstate_r ()
+interface is confusing.
+.\" FIXME . https://sourceware.org/bugzilla/show_bug.cgi?id=3662
+It appears that the
+.I random_data
+type is intended to be opaque,
+but the implementation requires the user to either initialize the
+.I buf.state
+field to NULL or zero out the entire structure before the call.
+.SH SEE ALSO
+.BR drand48 (3),
+.BR rand (3),
+.BR random (3)
diff --git a/man/man3/rawmemchr.3 b/man/man3/rawmemchr.3
new file mode 100644
index 000000000..b62c8f10a
--- /dev/null
+++ b/man/man3/rawmemchr.3
@@ -0,0 +1 @@
+.so man3/memchr.3
diff --git a/man/man3/rcmd.3 b/man/man3/rcmd.3
new file mode 100644
index 000000000..8d200d429
--- /dev/null
+++ b/man/man3/rcmd.3
@@ -0,0 +1,304 @@
+'\" t
+.\"	$NetBSD: rcmd.3,v 1.9 1996/05/28 02:07:39 mrg Exp $
+.\"
+.\" Copyright (c) 1983, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)rcmd.3	8.1 (Berkeley) 6/4/93
+.\"
+.\" Contributed as Linux man page by David A. Holland, 970908
+.\" I have not checked whether the Linux situation is exactly the same.
+.\"
+.\" 2007-12-08, mtk, Converted from mdoc to man macros
+.\"
+.TH rcmd 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rcmd, rresvport, iruserok, ruserok, rcmd_af,
+rresvport_af, iruserok_af, ruserok_af \- routines for returning a
+stream to a remote command
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <netdb.h>    " "/* Or <unistd.h> on some systems */"
+.P
+.BI "int rcmd(char **restrict " ahost ", unsigned short " inport ,
+.BI "            const char *restrict " locuser ,
+.BI "            const char *restrict " remuser ,
+.BI "            const char *restrict " cmd ", int *restrict " fd2p );
+.P
+.BI "int rresvport(int *" port );
+.P
+.BI "int iruserok(uint32_t " raddr ", int " superuser ,
+.BI "            const char *" ruser ", const char *" luser );
+.BI "int ruserok(const char *" rhost ", int " superuser ,
+.BI "            const char *" ruser ", const char *" luser );
+.P
+.BI "int rcmd_af(char **restrict " ahost ", unsigned short " inport ,
+.BI "            const char *restrict " locuser ,
+.BI "            const char *restrict " remuser ,
+.BI "            const char *restrict " cmd ", int *restrict " fd2p ,
+.BI "            sa_family_t " af );
+.P
+.BI "int rresvport_af(int *" port ", sa_family_t " af );
+.P
+.BI "int iruserok_af(const void *restrict " raddr ", int " superuser ,
+.BI "            const char *restrict " ruser ", const char *restrict " luser ,
+.BI "            sa_family_t " af );
+.BI "int ruserok_af(const char *" rhost ", int " superuser ,
+.BI "            const char *" ruser ", const char *" luser ,
+.BI "            sa_family_t " af );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.ad l
+.P
+.BR rcmd (),
+.BR rcmd_af (),
+.BR rresvport (),
+.BR rresvport_af (),
+.BR iruserok (),
+.BR iruserok_af (),
+.BR ruserok (),
+.BR ruserok_af ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.ad
+.SH DESCRIPTION
+The
+.BR rcmd ()
+function is used by the superuser to execute a command on
+a remote machine using an authentication scheme based
+on privileged port numbers.
+The
+.BR rresvport ()
+function
+returns a file descriptor to a socket
+with an address in the privileged port space.
+The
+.BR iruserok ()
+and
+.BR ruserok ()
+functions are used by servers
+to authenticate clients requesting service with
+.BR rcmd ().
+All four functions are used by the
+.BR rshd (8)
+server (among others).
+.SS rcmd()
+The
+.BR rcmd ()
+function
+looks up the host
+.I *ahost
+using
+.BR gethostbyname (3),
+returning \-1 if the host does not exist.
+Otherwise,
+.I *ahost
+is set to the standard name of the host
+and a connection is established to a server
+residing at the well-known Internet port
+.IR inport .
+.P
+If the connection succeeds,
+a socket in the Internet domain of type
+.B SOCK_STREAM
+is returned to the caller, and given to the remote
+command as
+.I stdin
+and
+.IR stdout .
+If
+.I fd2p
+is nonzero, then an auxiliary channel to a control
+process will be set up, and a file descriptor for it will be placed
+in
+.IR *fd2p .
+The control process will return diagnostic
+output from the command (unit 2) on this channel, and will also
+accept bytes on this channel as being UNIX signal numbers, to be
+forwarded to the process group of the command.
+If
+.I fd2p
+is 0, then the
+.I stderr
+(unit 2 of the remote
+command) will be made the same as the
+.I stdout
+and no
+provision is made for sending arbitrary signals to the remote process,
+although you may be able to get its attention by using out-of-band data.
+.P
+The protocol is described in detail in
+.BR rshd (8).
+.SS rresvport()
+The
+.BR rresvport ()
+function is used to obtain a socket with a privileged
+port bound to it.
+This socket is suitable for use by
+.BR rcmd ()
+and several other functions.
+Privileged ports are those in the range 0 to 1023.
+Only a privileged process
+(on Linux, a process that has the
+.B CAP_NET_BIND_SERVICE
+capability in the user namespace governing its network namespace)
+is allowed to bind to a privileged port.
+In the glibc implementation,
+this function restricts its search to the ports from 512 to 1023.
+The
+.I port
+argument is value-result:
+the value it supplies to the call is used as the starting point
+for a circular search of the port range;
+on (successful) return, it contains the port number that was bound to.
+.\"
+.SS iruserok() and ruserok()
+The
+.BR iruserok ()
+and
+.BR ruserok ()
+functions take a remote host's IP address or name, respectively,
+two usernames and a flag indicating whether the local user's
+name is that of the superuser.
+Then, if the user is
+.I not
+the superuser, it checks the
+.I /etc/hosts.equiv
+file.
+If that lookup is not done, or is unsuccessful, the
+.I .rhosts
+in the local user's home directory is checked to see if the request for
+service is allowed.
+.P
+If this file does not exist, is not a regular file, is owned by anyone
+other than the user or the superuser, is writable by anyone other
+than the owner, or is hardlinked anywhere, the check automatically fails.
+Zero is returned if the machine name is listed in the
+.I hosts.equiv
+file, or the host and remote username are found in the
+.I .rhosts
+file; otherwise
+.BR iruserok ()
+and
+.BR ruserok ()
+return \-1.
+If the local domain (as obtained from
+.BR gethostname (2))
+is the same as the remote domain, only the machine name need be specified.
+.P
+If the IP address of the remote host is known,
+.BR iruserok ()
+should be used in preference to
+.BR ruserok (),
+as it does not require trusting the DNS server for the remote host's domain.
+.SS *_af() variants
+All of the functions described above work with IPv4
+.RB ( AF_INET )
+sockets.
+The "_af" variants take an extra argument that allows the
+socket address family to be specified.
+For these functions, the
+.I af
+argument can be specified as
+.B AF_INET
+or
+.BR AF_INET6 .
+In addition,
+.BR rcmd_af ()
+supports the use of
+.BR AF_UNSPEC .
+.SH RETURN VALUE
+The
+.BR rcmd ()
+function
+returns a valid socket descriptor on success.
+It returns \-1 on error and prints a diagnostic message on the standard error.
+.P
+The
+.BR rresvport ()
+function
+returns a valid, bound socket descriptor on success.
+On failure, it returns \-1 and sets
+.I errno
+to indicate the error.
+The error code
+.B EAGAIN
+is overloaded to mean: "All network ports in use".
+.P
+For information on the return from
+.BR ruserok ()
+and
+.BR iruserok (),
+see above.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR rcmd (),
+.BR rcmd_af ()
+T}	Thread safety	MT-Unsafe
+T{
+.na
+.nh
+.BR rresvport (),
+.BR rresvport_af ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR iruserok (),
+.BR ruserok (),
+.BR iruserok_af (),
+.BR ruserok_af ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+.TP
+.BR iruserok_af ()
+.TQ
+.BR rcmd_af ()
+.TQ
+.BR rresvport_af ()
+.TQ
+.BR ruserok_af ()
+glibc 2.2.
+.P
+Solaris, 4.2BSD.
+The "_af" variants are more recent additions,
+and are not present on as wide a range of systems.
+.SH BUGS
+.BR iruserok ()
+and
+.BR iruserok_af ()
+are declared in glibc headers only since glibc 2.12.
+.\" Bug filed 25 Nov 2007:
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=5399
+.SH SEE ALSO
+.BR rlogin (1),
+.BR rsh (1),
+.BR rexec (3),
+.BR rexecd (8),
+.BR rlogind (8),
+.BR rshd (8)
diff --git a/man/man3/rcmd_af.3 b/man/man3/rcmd_af.3
new file mode 100644
index 000000000..b58efefab
--- /dev/null
+++ b/man/man3/rcmd_af.3
@@ -0,0 +1 @@
+.so man3/rcmd.3
diff --git a/man/man3/re_comp.3 b/man/man3/re_comp.3
new file mode 100644
index 000000000..51dd17821
--- /dev/null
+++ b/man/man3/re_comp.3
@@ -0,0 +1,75 @@
+'\" t
+.\" Copyright (C), 1995, Graeme W. Wilford. (Wilf.)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Wed Jun 14 16:10:28 BST 1995 Wilf. (G.Wilford@@ee.surrey.ac.uk)
+.\"
+.TH re_comp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+re_comp, re_exec \- BSD regex functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #define _REGEX_RE_COMP
+.B #include <sys/types.h>
+.B #include <regex.h>
+.P
+.BI "[[deprecated]] char *re_comp(const char *" regex );
+.BI "[[deprecated]] int re_exec(const char *" string );
+.fi
+.SH DESCRIPTION
+.BR re_comp ()
+is used to compile the null-terminated regular expression pointed to by
+.IR regex .
+The compiled pattern occupies a static area, the pattern buffer,
+which is overwritten by subsequent use of
+.BR re_comp ().
+If
+.I regex
+is NULL,
+no operation is performed and the pattern buffer's contents are not
+altered.
+.P
+.BR re_exec ()
+is used to assess whether the null-terminated string pointed to by
+.I string
+matches the previously compiled
+.IR regex .
+.SH RETURN VALUE
+.BR re_comp ()
+returns NULL on successful compilation of
+.I regex
+otherwise it returns a pointer to an appropriate error message.
+.P
+.BR re_exec ()
+returns 1 for a successful match, zero for failure.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR re_comp (),
+.BR re_exec ()
+T}	Thread safety	MT-Unsafe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD.
+.P
+These functions are obsolete; the functions documented in
+.BR regcomp (3)
+should be used instead.
+.SH SEE ALSO
+.BR regcomp (3),
+.BR regex (7),
+GNU regex manual
diff --git a/man/man3/re_exec.3 b/man/man3/re_exec.3
new file mode 100644
index 000000000..36aba3917
--- /dev/null
+++ b/man/man3/re_exec.3
@@ -0,0 +1 @@
+.so man3/re_comp.3
diff --git a/man/man3/readdir.3 b/man/man3/readdir.3
new file mode 100644
index 000000000..731e25c85
--- /dev/null
+++ b/man/man3/readdir.3
@@ -0,0 +1,304 @@
+'\" t
+.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (C) 2008, 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 16:09:49 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 11 June 1995 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified 22 July 1996 by Andries Brouwer (aeb@cwi.nl)
+.\" 2007-07-30 Ulrich Drepper <drepper@redhat.com>, mtk:
+.\"     Rework discussion of nonstandard structure fields.
+.\"
+.TH readdir 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+readdir \- read a directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <dirent.h>
+.P
+.BI "struct dirent *readdir(DIR *" dirp );
+.fi
+.SH DESCRIPTION
+The
+.BR readdir ()
+function returns a pointer to a \fIdirent\fP structure
+representing the next directory entry in the directory stream pointed
+to by \fIdirp\fP.
+It returns NULL on reaching the end of the directory stream or if
+an error occurred.
+.P
+In the glibc implementation, the
+.I dirent
+structure is defined as follows:
+.P
+.in +4n
+.EX
+struct dirent {
+    ino_t          d_ino;       /* Inode number */
+    off_t          d_off;       /* Not an offset; see below */
+    unsigned short d_reclen;    /* Length of this record */
+    unsigned char  d_type;      /* Type of file; not supported
+                                   by all filesystem types */
+    char           d_name[256]; /* Null\-terminated filename */
+};
+.EE
+.in
+.P
+The only fields in the
+.I dirent
+structure that are mandated by POSIX.1 are
+.I d_name
+and
+.IR d_ino .
+The other fields are unstandardized, and not present on all systems;
+see NOTES below for some further details.
+.P
+The fields of the
+.I dirent
+structure are as follows:
+.TP
+.I d_ino
+This is the inode number of the file.
+.TP
+.I d_off
+The value returned in
+.I d_off
+is the same as would be returned by calling
+.BR telldir (3)
+at the current position in the directory stream.
+Be aware that despite its type and name, the
+.I d_off
+field is seldom any kind of directory offset on modern filesystems.
+.\" https://lwn.net/Articles/544298/
+Applications should treat this field as an opaque value,
+making no assumptions about its contents; see also
+.BR telldir (3).
+.TP
+.I d_reclen
+This is the size (in bytes) of the returned record.
+This may not match the size of the structure definition shown above;
+see NOTES.
+.TP
+.I d_type
+This field contains a value indicating the file type,
+making it possible to avoid the expense of calling
+.BR lstat (2)
+if further actions depend on the type of the file.
+.IP
+When a suitable feature test macro is defined
+.RB ( _DEFAULT_SOURCE
+since glibc 2.19, or
+.B _BSD_SOURCE
+on glibc 2.19 and earlier),
+glibc defines the following macro constants for the value returned in
+.IR d_type :
+.RS
+.TP 12
+.B DT_BLK
+This is a block device.
+.TP
+.B DT_CHR
+This is a character device.
+.TP
+.B DT_DIR
+This is a directory.
+.TP
+.B DT_FIFO
+This is a named pipe (FIFO).
+.TP
+.B DT_LNK
+This is a symbolic link.
+.TP
+.B DT_REG
+This is a regular file.
+.TP
+.B DT_SOCK
+This is a UNIX domain socket.
+.TP
+.B DT_UNKNOWN
+The file type could not be determined.
+.RE
+.IP
+Currently,
+.\" kernel 2.6.27
+.\" The same sentence is in getdents.2
+only some filesystems (among them: Btrfs, ext2, ext3, and ext4)
+have full support for returning the file type in
+.IR d_type .
+All applications must properly handle a return of
+.BR DT_UNKNOWN .
+.TP
+.I d_name
+This field contains the null terminated filename.
+.IR "See NOTES" .
+.P
+The data returned by
+.BR readdir ()
+may be overwritten by subsequent calls to
+.BR readdir ()
+for the same directory stream.
+.SH RETURN VALUE
+On success,
+.BR readdir ()
+returns a pointer to a
+.I dirent
+structure.
+(This structure may be statically allocated; do not attempt to
+.BR free (3)
+it.)
+.P
+If the end of the directory stream is reached, NULL is returned and
+.I errno
+is not changed.
+If an error occurs, NULL is returned and
+.I errno
+is set to indicate the error.
+To distinguish end of stream from an error, set
+.I errno
+to zero before calling
+.BR readdir ()
+and then check the value of
+.I errno
+if NULL is returned.
+.SH ERRORS
+.TP
+.B EBADF
+Invalid directory stream descriptor \fIdirp\fP.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR readdir ()
+T}	Thread safety	MT-Unsafe race:dirstream
+.TE
+.P
+In the current POSIX.1 specification (POSIX.1-2008),
+.BR readdir ()
+is not required to be thread-safe.
+However, in modern implementations (including the glibc implementation),
+concurrent calls to
+.BR readdir ()
+that specify different directory streams are thread-safe.
+In cases where multiple threads must read from the same directory stream,
+using
+.BR readdir ()
+with external synchronization is still preferable to the use of the deprecated
+.BR readdir_r (3)
+function.
+It is expected that a future version of POSIX.1
+.\" FIXME .
+.\" http://www.austingroupbugs.net/view.php?id=696
+will require that
+.BR readdir ()
+be thread-safe when concurrently employed on different directory streams.
+.SH VERSIONS
+Only the fields
+.I d_name
+and (as an XSI extension)
+.I d_ino
+are specified in POSIX.1.
+.\" POSIX.1-2001, POSIX.1-2008
+Other than Linux, the
+.I d_type
+field is available mainly only on BSD systems.
+The remaining fields are available on many, but not all systems.
+Under glibc,
+programs can check for the availability of the fields not defined
+in POSIX.1 by testing whether the macros
+.BR _DIRENT_HAVE_D_NAMLEN ,
+.BR _DIRENT_HAVE_D_RECLEN ,
+.BR _DIRENT_HAVE_D_OFF ,
+or
+.B _DIRENT_HAVE_D_TYPE
+are defined.
+.\"
+.SS The d_name field
+The
+.I dirent
+structure definition shown above is taken from the glibc headers,
+and shows the
+.I d_name
+field with a fixed size.
+.P
+.IR Warning :
+applications should avoid any dependence on the size of the
+.I d_name
+field.
+POSIX defines it as
+.IR "char\ d_name[]",
+a character array of unspecified size, with at most
+.B NAME_MAX
+characters preceding the terminating null byte (\[aq]\e0\[aq]).
+.P
+POSIX.1 explicitly notes that this field should not be used as an lvalue.
+The standard also notes that the use of
+.I sizeof(d_name)
+is incorrect; use
+.I strlen(d_name)
+instead.
+(On some systems, this field is defined as
+.IR char\~d_name[1] !)
+By implication, the use
+.I sizeof(struct dirent)
+to capture the size of the record including the size of
+.I d_name
+is also incorrect.
+.P
+Note that while the call
+.P
+.in +4n
+.EX
+fpathconf(fd, _PC_NAME_MAX)
+.EE
+.in
+.P
+returns the value 255 for most filesystems,
+on some filesystems (e.g., CIFS, Windows SMB servers),
+the null-terminated filename that is (correctly) returned in
+.I d_name
+can actually exceed this size.
+In such cases, the
+.I d_reclen
+field will contain a value that exceeds the size of the glibc
+.I dirent
+structure shown above.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH NOTES
+A directory stream is opened using
+.BR opendir (3).
+.P
+The order in which filenames are read by successive calls to
+.BR readdir ()
+depends on the filesystem implementation;
+it is unlikely that the names will be sorted in any fashion.
+.SH SEE ALSO
+.BR getdents (2),
+.BR read (2),
+.BR closedir (3),
+.BR dirfd (3),
+.BR ftw (3),
+.BR offsetof (3),
+.BR opendir (3),
+.BR readdir_r (3),
+.BR rewinddir (3),
+.BR scandir (3),
+.BR seekdir (3),
+.BR telldir (3)
diff --git a/man/man3/readdir_r.3 b/man/man3/readdir_r.3
new file mode 100644
index 000000000..099591f41
--- /dev/null
+++ b/man/man3/readdir_r.3
@@ -0,0 +1,145 @@
+'\" t
+.\" Copyright (C) 2008, 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2016 Florian Weimer <fweimer@redhat.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH readdir_r 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+readdir_r \- read a directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <dirent.h>
+.P
+.BI "[[deprecated]] int readdir_r(DIR *restrict " dirp ,
+.BI "                             struct dirent *restrict " entry ,
+.BI "                             struct dirent **restrict " result );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR readdir_r ():
+.nf
+    _POSIX_C_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+This function is deprecated; use
+.BR readdir (3)
+instead.
+.P
+The
+.BR readdir_r ()
+function was invented as a reentrant version of
+.BR readdir (3).
+It reads the next directory entry from the directory stream
+.IR dirp ,
+and returns it in the caller-allocated buffer pointed to by
+.IR entry .
+For details of the
+.I dirent
+structure, see
+.BR readdir (3).
+.P
+A pointer to the returned buffer is placed in
+.IR *result ;
+if the end of the directory stream was encountered,
+then NULL is instead returned in
+.IR *result .
+.P
+It is recommended that applications use
+.BR readdir (3)
+instead of
+.BR readdir_r ().
+Furthermore, since glibc 2.24, glibc deprecates
+.BR readdir_r ().
+The reasons are as follows:
+.IP \[bu] 3
+On systems where
+.B NAME_MAX
+is undefined, calling
+.BR readdir_r ()
+may be unsafe because the interface does not allow the caller to specify
+the length of the buffer used for the returned directory entry.
+.IP \[bu]
+On some systems,
+.BR readdir_r ()
+can't read directory entries with very long names.
+When the glibc implementation encounters such a name,
+.BR readdir_r ()
+fails with the error
+.B ENAMETOOLONG
+.IR "after the final directory entry has been read" .
+On some other systems,
+.BR readdir_r ()
+may return a success status, but the returned
+.I d_name
+field may not be null terminated or may be truncated.
+.IP \[bu]
+In the current POSIX.1 specification (POSIX.1-2008),
+.BR readdir (3)
+is not required to be thread-safe.
+However, in modern implementations (including the glibc implementation),
+concurrent calls to
+.BR readdir (3)
+that specify different directory streams are thread-safe.
+Therefore, the use of
+.BR readdir_r ()
+is generally unnecessary in multithreaded programs.
+In cases where multiple threads must read from the same directory stream,
+using
+.BR readdir (3)
+with external synchronization is still preferable to the use of
+.BR readdir_r (),
+for the reasons given in the points above.
+.IP \[bu]
+It is expected that a future version of POSIX.1
+.\" FIXME .
+.\" http://www.austingroupbugs.net/view.php?id=696
+will make
+.BR readdir_r ()
+obsolete, and require that
+.BR readdir (3)
+be thread-safe when concurrently employed on different directory streams.
+.SH RETURN VALUE
+The
+.BR readdir_r ()
+function returns 0 on success.
+On error, it returns a positive error number (listed under ERRORS).
+If the end of the directory stream is reached,
+.BR readdir_r ()
+returns 0, and returns NULL in
+.IR *result .
+.SH ERRORS
+.TP
+.B EBADF
+Invalid directory stream descriptor \fIdirp\fP.
+.TP
+.B ENAMETOOLONG
+A directory entry whose name was too long to be read was encountered.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR readdir_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR readdir (3)
diff --git a/man/man3/realloc.3 b/man/man3/realloc.3
new file mode 100644
index 000000000..a4b9d4455
--- /dev/null
+++ b/man/man3/realloc.3
@@ -0,0 +1 @@
+.so man3/malloc.3
diff --git a/man/man3/reallocarray.3 b/man/man3/reallocarray.3
new file mode 100644
index 000000000..a4b9d4455
--- /dev/null
+++ b/man/man3/reallocarray.3
@@ -0,0 +1 @@
+.so man3/malloc.3
diff --git a/man/man3/realpath.3 b/man/man3/realpath.3
new file mode 100644
index 000000000..512807217
--- /dev/null
+++ b/man/man3/realpath.3
@@ -0,0 +1,231 @@
+'\" t
+.\" Copyright (C) 1999 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Rewritten old page, 990824, aeb@cwi.nl
+.\" 2004-12-14, mtk, added discussion of resolved_path == NULL
+.\"
+.TH realpath 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+realpath \- return the canonicalized absolute pathname
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <limits.h>
+.B #include <stdlib.h>
+.P
+.BI "char *realpath(const char *restrict " path ,
+.BI "               char *restrict " resolved_path );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR realpath ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR realpath ()
+expands all symbolic links and resolves references
+to
+.IR "/./" ", " "/../"
+and extra \[aq]/\[aq]
+characters in the null-terminated string named by
+.I path
+to produce a canonicalized absolute pathname.
+The resulting pathname is stored as a null-terminated string,
+up to a maximum of
+.B PATH_MAX
+bytes,
+in the buffer pointed to by
+.IR resolved_path .
+The resulting path will have no symbolic link,
+.I "/./"
+or
+.I "/../"
+components.
+.P
+If
+.I resolved_path
+is specified as NULL, then
+.BR realpath ()
+uses
+.BR malloc (3)
+to allocate a buffer of up to
+.B PATH_MAX
+bytes to hold the resolved pathname,
+and returns a pointer to this buffer.
+The caller should deallocate this buffer using
+.BR free (3).
+.\" Even if we use resolved_path == NULL, then realpath() will still
+.\" return ENAMETOOLONG if the resolved pathname would exceed PATH_MAX
+.\" bytes -- MTK, Dec 04
+.SH RETURN VALUE
+If there is no error,
+.BR realpath ()
+returns a pointer to the
+.IR resolved_path .
+.P
+Otherwise, it returns NULL, the contents
+of the array
+.I resolved_path
+are undefined, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Read or search permission was denied for a component of the path prefix.
+.TP
+.B EINVAL
+.I path
+is NULL.
+.\" (In libc5 this would just cause a segfault.)
+(Before glibc 2.3,
+this error is also returned if
+.I resolved_path
+is NULL.)
+.TP
+.B EIO
+An I/O error occurred while reading from the filesystem.
+.TP
+.B ELOOP
+Too many symbolic links were encountered in translating the pathname.
+.TP
+.B ENAMETOOLONG
+A component of a pathname exceeded
+.B NAME_MAX
+characters, or an entire pathname exceeded
+.B PATH_MAX
+characters.
+.TP
+.B ENOENT
+The named file does not exist.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ENOTDIR
+A component of the path prefix is not a directory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR realpath ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.SS GNU extensions
+If the call fails with either
+.B EACCES
+or
+.B ENOENT
+and
+.I resolved_path
+is not NULL, then the prefix of
+.I path
+that is not readable or does not exist is returned in
+.IR resolved_path .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+4.4BSD, POSIX.1-2001, Solaris.
+.P
+POSIX.1-2001 says that the behavior if
+.I resolved_path
+is NULL is implementation-defined.
+POSIX.1-2008 specifies the behavior described in this page.
+.P
+In 4.4BSD and Solaris, the limit on the pathname length is
+.B MAXPATHLEN
+(found in \fI<sys/param.h>\fP).
+SUSv2 prescribes
+.B PATH_MAX
+and
+.BR NAME_MAX ,
+as found in \fI<limits.h>\fP or provided by the
+.BR pathconf (3)
+function.
+A typical source fragment would be
+.P
+.in +4n
+.EX
+#ifdef PATH_MAX
+  path_max = PATH_MAX;
+#else
+  path_max = pathconf(path, _PC_PATH_MAX);
+  if (path_max <= 0)
+    path_max = 4096;
+#endif
+.EE
+.in
+.P
+(But see the BUGS section.)
+.\".P
+.\"     2012-05-05, According to Casper Dik, the statement about
+.\"     Solaris was not true at least as far back as 1997, and
+.\"     may never have been true.
+.\"
+.\" The 4.4BSD, Linux and SUSv2 versions always return an absolute
+.\" pathname.
+.\" Solaris may return a relative pathname when the
+.\" .I path
+.\" argument is relative.
+.\" The prototype of
+.\" .BR realpath ()
+.\" is given in \fI<unistd.h>\fP in libc4 and libc5,
+.\" but in \fI<stdlib.h>\fP everywhere else.
+.SH BUGS
+The POSIX.1-2001 standard version of this function is broken by design,
+since it is impossible to determine a suitable size for the output buffer,
+.IR resolved_path .
+According to POSIX.1-2001 a buffer of size
+.B PATH_MAX
+suffices, but
+.B PATH_MAX
+need not be a defined constant, and may have to be obtained using
+.BR pathconf (3).
+And asking
+.BR pathconf (3)
+does not really help, since, on the one hand POSIX warns that
+the result of
+.BR pathconf (3)
+may be huge and unsuitable for mallocing memory,
+and on the other hand
+.BR pathconf (3)
+may return \-1 to signify that
+.B PATH_MAX
+is not bounded.
+The
+.I "resolved_path\ ==\ NULL"
+feature, not standardized in POSIX.1-2001,
+but standardized in POSIX.1-2008, allows this design problem to be avoided.
+.\" .P
+.\" The libc4 and libc5 implementation contained a buffer overflow
+.\" (fixed in libc-5.4.13).
+.\" Thus, set-user-ID programs like
+.\" .BR mount (8)
+.\" needed a private version.
+.SH SEE ALSO
+.BR realpath (1),
+.BR readlink (2),
+.BR canonicalize_file_name (3),
+.BR getcwd (3),
+.BR pathconf (3),
+.BR sysconf (3)
diff --git a/man/man3/recno.3 b/man/man3/recno.3
new file mode 100644
index 000000000..fa666f585
--- /dev/null
+++ b/man/man3/recno.3
@@ -0,0 +1,207 @@
+.\" Copyright (c) 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	@(#)recno.3	8.5 (Berkeley) 8/18/94
+.\"
+.TH recno 3 (date) "Linux man-pages (unreleased)"
+.UC 7
+.SH NAME
+recno \- record number database access method
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.ft B
+#include <sys/types.h>
+#include <db.h>
+.ft R
+.fi
+.SH DESCRIPTION
+.IR "Note well" :
+This page documents interfaces provided up until glibc 2.1.
+Since glibc 2.2, glibc no longer provides these interfaces.
+Probably, you are looking for the APIs provided by the
+.I libdb
+library instead.
+.P
+The routine
+.BR dbopen (3)
+is the library interface to database files.
+One of the supported file formats is record number files.
+The general description of the database access methods is in
+.BR dbopen (3),
+this manual page describes only the recno-specific information.
+.P
+The record number data structure is either variable or fixed-length
+records stored in a flat-file format, accessed by the logical record
+number.
+The existence of record number five implies the existence of records
+one through four, and the deletion of record number one causes
+record number five to be renumbered to record number four, as well
+as the cursor, if positioned after record number one, to shift down
+one record.
+.P
+The recno access-method-specific data structure provided to
+.BR dbopen (3)
+is defined in the
+.I <db.h>
+include file as follows:
+.P
+.in +4n
+.EX
+typedef struct {
+    unsigned long flags;
+    unsigned int  cachesize;
+    unsigned int  psize;
+    int           lorder;
+    size_t        reclen;
+    unsigned char bval;
+    char         *bfname;
+} RECNOINFO;
+.EE
+.in
+.P
+The elements of this structure are defined as follows:
+.TP
+.I flags
+The flag value is specified by ORing
+any of the following values:
+.RS
+.TP
+.B R_FIXEDLEN
+The records are fixed-length, not byte delimited.
+The structure element
+.I reclen
+specifies the length of the record, and the structure element
+.I bval
+is used as the pad character.
+Any records, inserted into the database, that are less than
+.I reclen
+bytes long are automatically padded.
+.TP
+.B R_NOKEY
+In the interface specified by
+.BR dbopen (3),
+the sequential record retrieval fills in both the caller's key and
+data structures.
+If the
+.B R_NOKEY
+flag is specified, the
+.I cursor
+routines are not required to fill in the key structure.
+This permits applications to retrieve records at the end of files without
+reading all of the intervening records.
+.TP
+.B R_SNAPSHOT
+This flag requires that a snapshot of the file be taken when
+.BR dbopen (3)
+is called, instead of permitting any unmodified records to be read from
+the original file.
+.RE
+.TP
+.I cachesize
+A suggested maximum size, in bytes, of the memory cache.
+This value is
+.B only
+advisory, and the access method will allocate more memory rather than fail.
+If
+.I cachesize
+is  0 (no size is specified), a default cache is used.
+.TP
+.I psize
+The recno access method stores the in-memory copies of its records
+in a btree.
+This value is the size (in bytes) of the pages used for nodes in that tree.
+If
+.I psize
+is 0 (no page size is specified), a page size is chosen based on the
+underlying filesystem I/O block size.
+See
+.BR btree (3)
+for more information.
+.TP
+.I lorder
+The byte order for integers in the stored database metadata.
+The number should represent the order as an integer; for example,
+big endian order would be the number 4,321.
+If
+.I lorder
+is 0 (no order is specified), the current host order is used.
+.TP
+.I reclen
+The length of a fixed-length record.
+.TP
+.I bval
+The delimiting byte to be used to mark the end of a record for
+variable-length records, and the pad character for fixed-length
+records.
+If no value is specified, newlines ("\en") are used to mark the end
+of variable-length records and fixed-length records are padded with
+spaces.
+.TP
+.I bfname
+The recno access method stores the in-memory copies of its records
+in a btree.
+If
+.I bfname
+is non-NULL, it specifies the name of the btree file,
+as if specified as the filename for a
+.BR dbopen (3)
+of a btree file.
+.P
+The data part of the key/data pair used by the
+.I recno
+access method
+is the same as other access methods.
+The key is different.
+The
+.I data
+field of the key should be a pointer to a memory location of type
+.IR recno_t ,
+as defined in the
+.I <db.h>
+include file.
+This type is normally the largest unsigned integral type available to
+the implementation.
+The
+.I size
+field of the key should be the size of that type.
+.P
+Because there can be no metadata associated with the underlying
+recno access method files, any changes made to the default values
+(e.g., fixed record length or byte separator value) must be explicitly
+specified each time the file is opened.
+.P
+In the interface specified by
+.BR dbopen (3),
+using the
+.I put
+interface to create a new record will cause the creation of multiple,
+empty records if the record number is more than one greater than the
+largest record currently in the database.
+.SH ERRORS
+The
+.I recno
+access method routines may fail and set
+.I errno
+for any of the errors specified for the library routine
+.BR dbopen (3)
+or the following:
+.TP
+.B EINVAL
+An attempt was made to add a record to a fixed-length database that
+was too large to fit.
+.SH BUGS
+Only big and little endian byte order is supported.
+.SH SEE ALSO
+.BR btree (3),
+.BR dbopen (3),
+.BR hash (3),
+.BR mpool (3)
+.P
+.IR "Document Processing in a Relational Database System" ,
+Michael Stonebraker, Heidi Stettner, Joseph Kalash, Antonin Guttman,
+Nadene Lynn, Memorandum No. UCB/ERL M82/32, May 1982.
diff --git a/man/man3/regcomp.3 b/man/man3/regcomp.3
new file mode 100644
index 000000000..c0daaf0ff
--- /dev/null
+++ b/man/man3/regcomp.3
@@ -0,0 +1 @@
+.so man3/regex.3
diff --git a/man/man3/regerror.3 b/man/man3/regerror.3
new file mode 100644
index 000000000..c0daaf0ff
--- /dev/null
+++ b/man/man3/regerror.3
@@ -0,0 +1 @@
+.so man3/regex.3
diff --git a/man/man3/regex.3 b/man/man3/regex.3
new file mode 100644
index 000000000..a4e89c100
--- /dev/null
+++ b/man/man3/regex.3
@@ -0,0 +1,411 @@
+'\" t
+.\" Copyright (C), 1995, Graeme W. Wilford. (Wilf.)
+.\" Copyright 2023, Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
+.\" Copyright 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Wed Jun 14 16:10:28 BST 1995 Wilf. (G.Wilford@ee.surrey.ac.uk)
+.\" Tiny change in formatting - aeb, 950812
+.\" Modified 8 May 1998 by Joseph S. Myers (jsm28@cam.ac.uk)
+.\"
+.\" show the synopsis section nicely
+.TH regex 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+regcomp, regexec, regerror, regfree \- POSIX regex functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <regex.h>
+.P
+.BI "int regcomp(regex_t *restrict " preg ", const char *restrict " regex ,
+.BI "            int " cflags );
+.BI "int regexec(const regex_t *restrict " preg \
+", const char *restrict " string ,
+.BI "            size_t " nmatch ", \
+regmatch_t " pmatch "[_Nullable restrict ." nmatch ],
+.BI "            int " eflags );
+.P
+.BI "size_t regerror(int " errcode ", const regex_t *_Nullable restrict " preg ,
+.BI "            char " errbuf "[_Nullable restrict ." errbuf_size ],
+.BI "            size_t " errbuf_size );
+.BI "void regfree(regex_t *" preg );
+.P
+.B typedef struct {
+.B "    size_t    re_nsub;"
+.B } regex_t;
+.P
+.B typedef struct {
+.B "    regoff_t  rm_so;"
+.B "    regoff_t  rm_eo;"
+.B } regmatch_t;
+.P
+.BR typedef " /* ... */  " regoff_t;
+.fi
+.SH DESCRIPTION
+.SS Compilation
+.BR regcomp ()
+is used to compile a regular expression into a form that is suitable
+for subsequent
+.BR regexec ()
+searches.
+.P
+On success, the pattern buffer at
+.I *preg
+is initialized.
+.I regex
+is a null-terminated string.
+The locale must be the same when running
+.BR regexec ().
+.P
+After
+.BR regcomp ()
+succeeds,
+.I preg->re_nsub
+holds the number of subexpressions in
+.IR regex .
+Thus, a value of
+.I preg->re_nsub
++ 1
+passed as
+.I nmatch
+to
+.BR regexec ()
+is sufficient to capture all matches.
+.P
+.I cflags
+is the
+bitwise OR
+of zero or more of the following:
+.TP
+.B REG_EXTENDED
+Use
+POSIX
+Extended Regular Expression syntax when interpreting
+.IR regex .
+If not set,
+POSIX
+Basic Regular Expression syntax is used.
+.TP
+.B REG_ICASE
+Do not differentiate case.
+Subsequent
+.BR regexec ()
+searches using this pattern buffer will be case insensitive.
+.TP
+.B REG_NOSUB
+Report only overall success.
+.BR regexec ()
+will use only
+.I pmatch
+for
+.BR REG_STARTEND ,
+ignoring
+.IR nmatch .
+.TP
+.B REG_NEWLINE
+Match-any-character operators don't match a newline.
+.IP
+A nonmatching list
+.RB ( [\[ha]...\&] )
+not containing a newline does not match a newline.
+.IP
+Match-beginning-of-line operator
+.RB ( \[ha] )
+matches the empty string immediately after a newline, regardless of
+whether
+.IR eflags ,
+the execution flags of
+.BR regexec (),
+contains
+.BR REG_NOTBOL .
+.IP
+Match-end-of-line operator
+.RB ( $ )
+matches the empty string immediately before a newline, regardless of
+whether
+.I eflags
+contains
+.BR REG_NOTEOL .
+.SS Matching
+.BR regexec ()
+is used to match a null-terminated string
+against the compiled pattern buffer in
+.IR *preg ,
+which must have been initialised with
+.BR regexec ().
+.I eflags
+is the
+bitwise OR
+of zero or more of the following flags:
+.TP
+.B REG_NOTBOL
+The match-beginning-of-line operator always fails to match (but see the
+compilation flag
+.B REG_NEWLINE
+above).
+This flag may be used when different portions of a string are passed to
+.BR regexec ()
+and the beginning of the string should not be interpreted as the
+beginning of the line.
+.TP
+.B REG_NOTEOL
+The match-end-of-line operator always fails to match (but see the
+compilation flag
+.B REG_NEWLINE
+above).
+.TP
+.B REG_STARTEND
+Match
+.RI [ "string + pmatch[0].rm_so" , " string + pmatch[0].rm_eo" )
+instead of
+.RI [ string , " string + strlen(string)" ).
+This allows matching embedded NUL bytes
+and avoids a
+.BR strlen (3)
+on known-length strings.
+If any matches are returned
+.RB ( REG_NOSUB
+wasn't passed to
+.BR regcomp (),
+the match succeeded, and
+.I nmatch
+> 0), they overwrite
+.I pmatch
+as usual, and the match offsets remain relative to
+.I string
+(not
+.IR "string + pmatch[0].rm_so" ).
+This flag is a BSD extension, not present in POSIX.
+.SS Match offsets
+Unless
+.B REG_NOSUB
+was passed to
+.BR regcomp (),
+it is possible to
+obtain the locations of matches within
+.IR string :
+.BR regexec ()
+fills
+.I nmatch
+elements of
+.I pmatch
+with results:
+.I pmatch[0]
+corresponds to the entire match,
+.I pmatch[1]
+to the first subexpression, etc.
+If there were more matches than
+.IR nmatch ,
+they are discarded;
+if fewer,
+unused elements of
+.I pmatch
+are filled with
+.BR \-1 s.
+.P
+Each returned valid
+.RB (non- \-1 )
+match corresponds to the range
+.RI [ "string + rm_so" , " string + rm_eo" ).
+.P
+.I regoff_t
+is a signed integer type
+capable of storing the largest value that can be stored in either an
+.I ptrdiff_t
+type or a
+.I ssize_t
+type.
+.SS Error reporting
+.BR regerror ()
+is used to turn the error codes that can be returned by both
+.BR regcomp ()
+and
+.BR regexec ()
+into error message strings.
+.P
+If
+.I preg
+isn't a null pointer,
+.I errcode
+must be the latest error returned from an operation on
+.IR preg .
+.P
+If
+.I errbuf_size
+isn't 0, up to
+.I errbuf_size
+bytes are copied to
+.IR errbuf ;
+the error string is always null-terminated, and truncated to fit.
+.SS Freeing
+.BR regfree ()
+deinitializes the pattern buffer at
+.IR *preg ,
+freeing any associated memory;
+.I *preg
+must have been initialized via
+.BR regcomp ().
+.SH RETURN VALUE
+.BR regcomp ()
+returns zero for a successful compilation or an error code for failure.
+.P
+.BR regexec ()
+returns zero for a successful match or
+.B REG_NOMATCH
+for failure.
+.P
+.BR regerror ()
+returns the size of the buffer required to hold the string.
+.SH ERRORS
+The following errors can be returned by
+.BR regcomp ():
+.TP
+.B REG_BADBR
+Invalid use of back reference operator.
+.TP
+.B REG_BADPAT
+Invalid use of pattern operators such as group or list.
+.TP
+.B REG_BADRPT
+Invalid use of repetition operators such as using \[aq]*\[aq]
+as the first character.
+.TP
+.B REG_EBRACE
+Un-matched brace interval operators.
+.TP
+.B REG_EBRACK
+Un-matched bracket list operators.
+.TP
+.B REG_ECOLLATE
+Invalid collating element.
+.TP
+.B REG_ECTYPE
+Unknown character class name.
+.TP
+.B REG_EEND
+Nonspecific error.
+This is not defined by POSIX.
+.TP
+.B REG_EESCAPE
+Trailing backslash.
+.TP
+.B REG_EPAREN
+Un-matched parenthesis group operators.
+.TP
+.B REG_ERANGE
+Invalid use of the range operator; for example, the ending point of the range
+occurs prior to the starting point.
+.TP
+.B REG_ESIZE
+Compiled regular expression requires a pattern buffer larger than 64\ kB.
+This is not defined by POSIX.
+.TP
+.B REG_ESPACE
+The regex routines ran out of memory.
+.TP
+.B REG_ESUBREG
+Invalid back reference to a subexpression.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR regcomp (),
+.BR regexec ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR regerror ()
+T}	Thread safety	MT-Safe env
+T{
+.na
+.nh
+.BR regfree ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Prior to POSIX.1-2008,
+.I regoff_t
+was required to be
+capable of storing the largest value that can be stored in either an
+.I off_t
+type or a
+.I ssize_t
+type.
+.SH CAVEATS
+.I re_nsub
+is only required to be initialized if
+.B REG_NOSUB
+wasn't specified, but all known implementations initialize it regardless.
+.\" glibc, musl, 4.4BSD, illumos
+.P
+Both
+.I regex_t
+and
+.I regmatch_t
+may (and do) have more members, in any order.
+Always reference them by name.
+.\" illumos has two more start/end pairs and the first one is of pointers
+.SH EXAMPLES
+.EX
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <regex.h>
+\&
+#define ARRAY_SIZE(arr) (sizeof((arr)) / sizeof((arr)[0]))
+\&
+static const char *const str =
+        "1) John Driverhacker;\en2) John Doe;\en3) John Foo;\en";
+static const char *const re = "John.*o";
+\&
+int main(void)
+{
+    static const char *s = str;
+    regex_t     regex;
+    regmatch_t  pmatch[1];
+    regoff_t    off, len;
+\&
+    if (regcomp(&regex, re, REG_NEWLINE))
+        exit(EXIT_FAILURE);
+\&
+    printf("String = \e"%s\e"\en", str);
+    printf("Matches:\en");
+\&
+    for (unsigned int i = 0; ; i++) {
+        if (regexec(&regex, s, ARRAY_SIZE(pmatch), pmatch, 0))
+            break;
+\&
+        off = pmatch[0].rm_so + (s \- str);
+        len = pmatch[0].rm_eo \- pmatch[0].rm_so;
+        printf("#%zu:\en", i);
+        printf("offset = %jd; length = %jd\en", (intmax_t) off,
+                (intmax_t) len);
+        printf("substring = \e"%.*s\e"\en", len, s + pmatch[0].rm_so);
+\&
+        s += pmatch[0].rm_eo;
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR grep (1),
+.BR regex (7)
+.P
+The glibc manual section,
+.I "Regular Expressions"
diff --git a/man/man3/regexec.3 b/man/man3/regexec.3
new file mode 100644
index 000000000..c0daaf0ff
--- /dev/null
+++ b/man/man3/regexec.3
@@ -0,0 +1 @@
+.so man3/regex.3
diff --git a/man/man3/regfree.3 b/man/man3/regfree.3
new file mode 100644
index 000000000..c0daaf0ff
--- /dev/null
+++ b/man/man3/regfree.3
@@ -0,0 +1 @@
+.so man3/regex.3
diff --git a/man/man3/register_printf_modifier.3 b/man/man3/register_printf_modifier.3
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3/register_printf_modifier.3
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3/register_printf_specifier.3 b/man/man3/register_printf_specifier.3
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3/register_printf_specifier.3
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3/register_printf_type.3 b/man/man3/register_printf_type.3
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3/register_printf_type.3
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3/registerrpc.3 b/man/man3/registerrpc.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/registerrpc.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/remainder.3 b/man/man3/remainder.3
new file mode 100644
index 000000000..2a937ee48
--- /dev/null
+++ b/man/man3/remainder.3
@@ -0,0 +1,234 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-08-10 Walter Harms
+.\"	(walter.harms@informatik.uni-oldenburg.de)
+.\" Modified 2003-11-18, 2004-10-05 aeb
+.\"
+.TH remainder 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+drem, dremf, dreml, remainder, remainderf, remainderl \- \
+floating-point remainder function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double remainder(double " x ", double " y );
+.BI "float remainderf(float " x ", float " y );
+.BI "long double remainderl(long double " x ", long double " y );
+.P
+/* Obsolete synonyms */
+.BI "[[deprecated]] double drem(double " x ", double " y );
+.BI "[[deprecated]] float dremf(float " x ", float " y );
+.BI "[[deprecated]] long double dreml(long double " x ", long double " y );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR remainder ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR remainderf (),
+.BR remainderl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR drem (),
+.BR dremf (),
+.BR dreml ():
+.nf
+    /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These
+functions compute the remainder of dividing
+.I x
+by
+.IR y .
+The return value is
+\fIx\fP\-\fIn\fP*\fIy\fP,
+where
+.I n
+is the value
+.IR "x\ /\ y" ,
+rounded to the nearest integer.
+If the absolute value of
+\fIx\fP\-\fIn\fP*\fIy\fP
+is 0.5,
+.I n
+is chosen to be even.
+.P
+These functions are unaffected by the current rounding mode (see
+.BR fenv (3)).
+.P
+The
+.BR drem ()
+function does precisely the same thing.
+.SH RETURN VALUE
+On success, these
+functions return the floating-point remainder,
+\fIx\fP\-\fIn\fP*\fIy\fP.
+If the return value is 0, it has the sign of
+.IR x .
+.P
+If
+.I x
+or
+.I y
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is an infinity,
+and
+.I y
+is not a NaN,
+a domain error occurs, and
+a NaN is returned.
+.P
+If
+.I y
+is zero,
+.\" FIXME . Instead, glibc gives a domain error even if x is a NaN
+and
+.I x
+is not a NaN,
+.\" Interestingly, remquo(3) does not have the same problem.
+a domain error occurs, and
+a NaN is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is an infinity and \fIy\fP is not a NaN
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.IP
+These functions do not set
+.I errno
+for this case.
+.TP
+Domain error: \fIy\fP is zero\" [XXX see bug above] and \fIx\fP is not a NaN
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR drem (),
+.BR dremf (),
+.BR dreml (),
+.BR remainder (),
+.BR remainderf (),
+.BR remainderl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.\" IEC 60559.
+.TP
+.BR remainder ()
+.TQ
+.BR remainderf ()
+.TQ
+.BR remainderl ()
+C11, POSIX.1-2008.
+.TP
+.BR drem ()
+.TQ
+.BR dremf ()
+.TQ
+.BR dreml ()
+None.
+.SH HISTORY
+.\" IEC 60559.
+.TP
+.BR remainder ()
+.TQ
+.BR remainderf ()
+.TQ
+.BR remainderl ()
+C99, POSIX.1-2001.
+.TP
+.BR drem ()
+4.3BSD.
+.TP
+.BR dremf ()
+.TQ
+.BR dreml ()
+Tru64, glibc2.
+.SH BUGS
+Before glibc 2.15,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6779
+the call
+.P
+.in +4n
+.EX
+remainder(nan(""), 0);
+.EE
+.in
+.P
+returned a NaN, as expected, but wrongly caused a domain error.
+Since glibc 2.15, a silent NaN (i.e., no domain error) is returned.
+.P
+Before glibc 2.15,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6783
+.I errno
+was not set to
+.B EDOM
+for the domain error that occurs when
+.I x
+is an infinity and
+.I y
+is not a NaN.
+.SH EXAMPLES
+The call "remainder(29.0, 3.0)" returns \-1.
+.SH SEE ALSO
+.BR div (3),
+.BR fmod (3),
+.BR remquo (3)
diff --git a/man/man3/remainderf.3 b/man/man3/remainderf.3
new file mode 100644
index 000000000..b7a5b23bf
--- /dev/null
+++ b/man/man3/remainderf.3
@@ -0,0 +1 @@
+.so man3/remainder.3
diff --git a/man/man3/remainderl.3 b/man/man3/remainderl.3
new file mode 100644
index 000000000..b7a5b23bf
--- /dev/null
+++ b/man/man3/remainderl.3
@@ -0,0 +1 @@
+.so man3/remainder.3
diff --git a/man/man3/remove.3 b/man/man3/remove.3
new file mode 100644
index 000000000..3e2c00df2
--- /dev/null
+++ b/man/man3/remove.3
@@ -0,0 +1,93 @@
+'\" t
+.\" This file is derived from unlink.2, which has the following copyright:
+.\"
+.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
+.\"             and Copyright (C) 1993 Ian Jackson.
+.\"
+.\" Edited into remove.3 shape by:
+.\" Graeme W. Wilford (G.Wilford@ee.surrey.ac.uk) on 13th July 1994
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH remove 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+remove \- remove a file or directory
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int remove(const char *" pathname );
+.fi
+.SH DESCRIPTION
+.BR remove ()
+deletes a name from the filesystem.
+It calls
+.BR unlink (2)
+for files, and
+.BR rmdir (2)
+for directories.
+.P
+If the removed name was the
+last link to a file and no processes have the file open, the file is
+deleted and the space it was using is made available for reuse.
+.P
+If the name was the last link to a file,
+but any processes still have the file open,
+the file will remain in existence until the last file
+descriptor referring to it is closed.
+.P
+If the name referred to a symbolic link, the link is removed.
+.P
+If the name referred to a socket, FIFO, or device, the name is removed,
+but processes which have the object open may continue to use it.
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+The errors that occur are those for
+.BR unlink (2)
+and
+.BR rmdir (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR remove ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, 4.3BSD.
+.\" .SH NOTES
+.\" Under libc4 and libc5,
+.\" .BR remove ()
+.\" was an alias for
+.\" .BR unlink (2)
+.\" (and hence would not remove directories).
+.SH BUGS
+Infelicities in the protocol underlying NFS can cause the unexpected
+disappearance of files which are still being used.
+.SH SEE ALSO
+.BR rm (1),
+.BR unlink (1),
+.BR link (2),
+.BR mknod (2),
+.BR open (2),
+.BR rename (2),
+.BR rmdir (2),
+.BR unlink (2),
+.BR mkfifo (3),
+.BR symlink (7)
diff --git a/man/man3/remque.3 b/man/man3/remque.3
new file mode 100644
index 000000000..a0c88361a
--- /dev/null
+++ b/man/man3/remque.3
@@ -0,0 +1 @@
+.so man3/insque.3
diff --git a/man/man3/remquo.3 b/man/man3/remquo.3
new file mode 100644
index 000000000..ee42f5f36
--- /dev/null
+++ b/man/man3/remquo.3
@@ -0,0 +1,138 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" based on glibc infopages
+.\" polished, aeb
+.\"
+.TH remquo 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+remquo, remquof, remquol \- remainder and part of quotient
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double remquo(double " x ", double " y ", int *" quo );
+.BI "float remquof(float " x ", float " y ", int *" quo );
+.BI "long double remquol(long double " x ", long double " y ", int *" quo );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR remquo (),
+.BR remquof (),
+.BR remquol ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions compute the remainder and part of the quotient
+upon division of
+.I x
+by
+.IR y .
+A few bits of the quotient are stored via the
+.I quo
+pointer.
+The remainder is returned as the function result.
+.P
+The value of the remainder is the same as that computed by the
+.BR remainder (3)
+function.
+.P
+The value stored via the
+.I quo
+pointer has the sign of
+.I x\~/\~y
+and agrees with the quotient in at least the low order 3 bits.
+.P
+For example, \fIremquo(29.0,\ 3.0)\fP returns \-1.0 and might store 2.
+Note that the actual quotient might not fit in an integer.
+.\" A possible application of this function might be the computation
+.\" of sin(x). Compute remquo(x, pi/2, &quo) or so.
+.\"
+.\" glibc, UnixWare: return 3 bits
+.\" MacOS 10: return 7 bits
+.SH RETURN VALUE
+On success, these functions return the same value as
+the analogous functions described in
+.BR remainder (3).
+.P
+If
+.I x
+or
+.I y
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is an infinity,
+and
+.I y
+is not a NaN,
+a domain error occurs, and
+a NaN is returned.
+.P
+If
+.I y
+is zero,
+and
+.I x
+is not a NaN,
+a domain error occurs, and
+a NaN is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is an infinity or \fIy\fP is 0, \
+and the other argument is not a NaN
+.\" .I errno
+.\" is set to
+.\" .BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.P
+These functions do not set
+.IR errno .
+.\" FIXME . Is it intentional that these functions do not set errno?
+.\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6802
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR remquo (),
+.BR remquof (),
+.BR remquol ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR fmod (3),
+.BR logb (3),
+.BR remainder (3)
diff --git a/man/man3/remquof.3 b/man/man3/remquof.3
new file mode 100644
index 000000000..458f05120
--- /dev/null
+++ b/man/man3/remquof.3
@@ -0,0 +1 @@
+.so man3/remquo.3
diff --git a/man/man3/remquol.3 b/man/man3/remquol.3
new file mode 100644
index 000000000..458f05120
--- /dev/null
+++ b/man/man3/remquol.3
@@ -0,0 +1 @@
+.so man3/remquo.3
diff --git a/man/man3/res_init.3 b/man/man3/res_init.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_init.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_mkquery.3 b/man/man3/res_mkquery.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_mkquery.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_nclose.3 b/man/man3/res_nclose.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_nclose.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_ninit.3 b/man/man3/res_ninit.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_ninit.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_nmkquery.3 b/man/man3/res_nmkquery.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_nmkquery.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_nquery.3 b/man/man3/res_nquery.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_nquery.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_nquerydomain.3 b/man/man3/res_nquerydomain.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_nquerydomain.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_nsearch.3 b/man/man3/res_nsearch.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_nsearch.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_nsend.3 b/man/man3/res_nsend.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_nsend.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_query.3 b/man/man3/res_query.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_query.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_querydomain.3 b/man/man3/res_querydomain.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_querydomain.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_search.3 b/man/man3/res_search.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_search.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/res_send.3 b/man/man3/res_send.3
new file mode 100644
index 000000000..87a6d0e83
--- /dev/null
+++ b/man/man3/res_send.3
@@ -0,0 +1 @@
+.so man3/resolver.3
diff --git a/man/man3/resolver.3 b/man/man3/resolver.3
new file mode 100644
index 000000000..c54337218
--- /dev/null
+++ b/man/man3/resolver.3
@@ -0,0 +1,511 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and (C) Copyright 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-25 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2004-10-31 by aeb
+.\"
+.TH resolver 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+res_ninit, res_nquery, res_nsearch, res_nquerydomain, res_nmkquery, res_nsend,
+res_nclose,
+res_init, res_query, res_search, res_querydomain, res_mkquery, res_send,
+dn_comp, dn_expand \-
+resolver routines
+.SH LIBRARY
+Resolver library
+.RI ( libresolv ", " \-lresolv )
+.SH SYNOPSIS
+.nf
+.B #include <netinet/in.h>
+.B #include <arpa/nameser.h>
+.B #include <resolv.h>
+.P
+.B struct __res_state;
+.B typedef struct __res_state *res_state;
+.P
+.BI "int res_ninit(res_state " statep );
+.P
+.BI "void res_nclose(res_state " statep );
+.P
+.BI "int res_nquery(res_state " statep ,
+.BI "           const char *" dname ", int " class ", int " type ,
+.BI "           unsigned char " answer [. anslen "], int " anslen );
+.P
+.BI "int res_nsearch(res_state " statep ,
+.BI "           const char *" dname ", int " class ", int " type ,
+.BI "           unsigned char " answer [. anslen "], int " anslen );
+.P
+.BI "int res_nquerydomain(res_state " statep ,
+.BI "           const char *" name ", const char *" domain ,
+.BI "           int " class ", int " type ", unsigned char " answer [. anslen ],
+.BI "           int " anslen );
+.P
+.BI "int res_nmkquery(res_state " statep ,
+.BI "           int " op ", const char *" dname ", int " class ,
+.BI "           int " type ", const unsigned char " data [. datalen "], \
+int " datalen ,
+.BI "           const unsigned char *" newrr ,
+.BI "           unsigned char " buf [. buflen "], int " buflen );
+.P
+.BI "int res_nsend(res_state " statep ,
+.BI "           const unsigned char " msg [. msglen "], int " msglen ,
+.BI "           unsigned char " answer [. anslen "], int " anslen );
+.P
+.BI "int dn_comp(const char *" exp_dn ", unsigned char " comp_dn [. length ],
+.BI "           int " length ", unsigned char **" dnptrs ,
+.BI "           unsigned char **" lastdnptr );
+.P
+.BI "int dn_expand(const unsigned char *" msg ,
+.BI "           const unsigned char *" eomorig ,
+.BI "           const unsigned char *" comp_dn ", char " exp_dn [. length ],
+.BI "           int " length );
+.P
+.B [[deprecated]] extern struct __res_state _res;
+.P
+.B [[deprecated]] int res_init(void);
+.P
+.B [[deprecated]]
+.BI "int res_query(const char *" dname ", int " class ", int " type ,
+.BI "           unsigned char " answer [. anslen "], int " anslen );
+.P
+.B [[deprecated]]
+.BI "int res_search(const char *" dname ", int " class ", int " type ,
+.BI "           unsigned char " answer [. anslen "], int " anslen );
+.P
+.B [[deprecated]]
+.BI "int res_querydomain(const char *" name ", const char *" domain ,
+.BI "           int " class ", int " type ", unsigned char " answer [. anslen ],
+.BI "           int " anslen );
+.P
+.B [[deprecated]]
+.BI "int res_mkquery(int " op ", const char *" dname ", int " class ,
+.BI "           int " type ", const unsigned char " data [. datalen "], \
+int " datalen ,
+.BI "           const unsigned char *" newrr ,
+.BI "           unsigned char " buf [. buflen "], int " buflen );
+.P
+.B [[deprecated]]
+.BI "int res_send(const unsigned char " msg [. msglen "], int " msglen ,
+.BI "           unsigned char " answer [. anslen "], int " anslen );
+.fi
+.SH DESCRIPTION
+.B Note:
+This page is incomplete (various resolver functions provided by glibc
+are not described) and likely out of date.
+.P
+The functions described below make queries to and interpret
+the responses from Internet domain name servers.
+.P
+The API consists of a set of more modern, reentrant functions
+and an older set of nonreentrant functions that have been superseded.
+The traditional resolver interfaces such as
+.BR res_init ()
+and
+.BR res_query ()
+use some static (global) state stored in the
+.I _res
+structure, rendering these functions non-thread-safe.
+BIND 8.2 introduced a set of new interfaces
+.BR res_ninit (),
+.BR res_nquery (),
+and so on, which take a
+.I res_state
+as their first argument, so you can use a per-thread resolver state.
+.P
+The
+.BR res_ninit ()
+and
+.BR res_init ()
+functions read the configuration files (see
+.BR resolv.conf (5))
+to get the default domain name and name
+server address(es).
+If no server is given, the local host is tried.
+If no domain is given, that associated with the local host is used.
+It can be overridden with the environment variable
+.BR LOCALDOMAIN .
+.BR res_ninit ()
+or
+.BR res_init ()
+is normally executed by the first call to one of the
+other functions.
+Every call to
+.BR res_ninit ()
+requires a corresponding call to
+.BR res_nclose ()
+to free memory allocated by
+.BR res_ninit ()
+and subsequent calls to
+.BR res_nquery ().
+.P
+The
+.BR res_nquery ()
+and
+.BR res_query ()
+functions query the name server for the
+fully qualified domain name \fIname\fP of specified \fItype\fP and
+\fIclass\fP.
+The reply is left in the buffer \fIanswer\fP of length
+\fIanslen\fP supplied by the caller.
+.P
+The
+.BR res_nsearch ()
+and
+.BR res_search ()
+functions make a query and waits for the response like
+.BR res_nquery ()
+and
+.BR res_query (),
+but in addition they implement the default and search
+rules controlled by
+.B RES_DEFNAMES
+and
+.B RES_DNSRCH
+(see description of
+\fI_res\fP options below).
+.P
+The
+.BR res_nquerydomain ()
+and
+.BR res_querydomain ()
+functions make a query using
+.BR res_nquery ()/ res_query ()
+on the concatenation of \fIname\fP and \fIdomain\fP.
+.P
+The following functions are lower-level routines used by
+.BR res_nquery ()/ res_query ().
+.P
+The
+.BR res_nmkquery ()
+and
+.BR res_mkquery ()
+functions construct a query message in \fIbuf\fP
+of length \fIbuflen\fP for the domain name \fIdname\fP.
+The query type
+\fIop\fP is one of the following (typically
+.BR QUERY ):
+.TP
+.B QUERY
+Standard query.
+.TP
+.B IQUERY
+Inverse query.
+This option was removed in glibc 2.26,
+.\" commit e4e794841e3140875f2aa86b90e2ada3d61e1244
+since it has not been supported by DNS servers for a very long time.
+.TP
+.B NS_NOTIFY_OP
+Notify secondary of SOA (Start of Authority) change.
+.P
+\fInewrr\fP is currently unused.
+.P
+The
+.BR res_nsend ()
+and
+.BR res_send ()
+function send a preformatted query given in
+\fImsg\fP of length \fImsglen\fP and returns the answer in \fIanswer\fP
+which is of length \fIanslen\fP.
+They will call
+.BR res_ninit ()/ res_init ()
+if it has not already been called.
+.P
+The
+.BR dn_comp ()
+function compresses the domain name \fIexp_dn\fP
+and stores it in the buffer \fIcomp_dn\fP of length \fIlength\fP.
+The compression uses an array of pointers \fIdnptrs\fP to previously
+compressed names in the current message.
+The first pointer points
+to the beginning of the message and the list ends with NULL.
+The limit of the array is specified by \fIlastdnptr\fP.
+If \fIdnptr\fP is NULL, domain names are not compressed.
+If \fIlastdnptr\fP is NULL, the list
+of labels is not updated.
+.P
+The
+.BR dn_expand ()
+function expands the compressed domain name
+\fIcomp_dn\fP to a full domain name, which is placed in the buffer
+\fIexp_dn\fP of size \fIlength\fP.
+The compressed name is contained
+in a query or reply message, and \fImsg\fP points to the beginning of
+the message.
+.P
+The resolver routines use configuration and state information
+contained in a
+.I __res_state
+structure (either passed as the
+.I statep
+argument, or in the global variable
+.IR _res ,
+in the case of the older nonreentrant functions).
+The only field of this structure that is normally manipulated by the
+user is the
+.I options
+field.
+This field can contain the bitwise "OR"
+of the following options:
+.TP
+.B RES_INIT
+True if
+.BR res_ninit ()
+or
+.BR res_init ()
+has been called.
+.TP
+.B RES_DEBUG
+Print debugging messages.
+This option is available only if glibc was built with debugging enabled,
+.\" See resolv/README.
+.\" Support for RES_DEBUG was made conditional in glibc 2.2.
+which is not the default.
+.TP
+.BR RES_AAONLY " (unimplemented; deprecated in glibc 2.25)"
+Accept authoritative answers only.
+.BR res_send ()
+continues until
+it finds an authoritative answer or returns an error.
+This option was present but unimplemented until glibc 2.24;
+since glibc 2.25, it is deprecated, and its usage produces a warning.
+.TP
+.B RES_USEVC
+Use TCP connections for queries rather than UDP datagrams.
+.TP
+.BR RES_PRIMARY " (unimplemented; deprecated in glibc 2.25)"
+Query primary domain name server only.
+This option was present but unimplemented until glibc 2.24;
+since glibc 2.25, it is deprecated, and its usage produces a warning.
+.TP
+.B RES_IGNTC
+Ignore truncation errors.
+Don't retry with TCP.
+.TP
+.B RES_RECURSE
+Set the recursion desired bit in queries.
+Recursion is carried out
+by the domain name server, not by
+.BR res_send ().
+[Enabled by default].
+.TP
+.B RES_DEFNAMES
+If set,
+.BR res_search ()
+will append the default domain name to
+single component names\[em]that is, those that do not contain a dot.
+[Enabled by default].
+.TP
+.B RES_STAYOPEN
+Used with
+.B RES_USEVC
+to keep the TCP connection open between queries.
+.TP
+.B RES_DNSRCH
+If set,
+.BR res_search ()
+will search for hostnames in the current
+domain and in parent domains.
+This option is used by
+.BR gethostbyname (3).
+[Enabled by default].
+.TP
+.B RES_INSECURE1
+Accept a response from a wrong server.
+This can be used to detect potential security hazards,
+but you need to compile glibc with debugging enabled and use
+.B RES_DEBUG
+option (for debug purpose only).
+.TP
+.B RES_INSECURE2
+Accept a response which contains a wrong query.
+This can be used to detect potential security hazards,
+but you need to compile glibc with debugging enabled and use
+.B RES_DEBUG
+option (for debug purpose only).
+.TP
+.B RES_NOALIASES
+Disable usage of
+.B HOSTALIASES
+environment variable.
+.TP
+.B RES_USE_INET6
+Try an AAAA query before an A query inside the
+.BR gethostbyname (3)
+function, and map IPv4 responses in IPv6 "tunneled form" if no AAAA records
+are found but an A record set exists.
+Since glibc 2.25, this option is deprecated,
+and its usage produces a warning;
+applications should use
+.BR getaddrinfo (3),
+rather than
+.BR gethostbyname (3).
+.TP
+.B RES_ROTATE
+Causes round-robin selection of name servers from among those listed.
+This has the effect of spreading the query load among all listed servers,
+rather than having all clients try the first listed server first every
+time.
+.TP
+.BR RES_NOCHECKNAME " (unimplemented; deprecated in glibc 2.25)"
+Disable the modern BIND checking of incoming hostnames and mail names
+for invalid characters such as underscore (_), non-ASCII,
+or control characters.
+This option was present until glibc 2.24;
+since glibc 2.25, it is deprecated, and its usage produces a warning.
+.TP
+.BR RES_KEEPTSIG " (unimplemented; deprecated in glibc 2.25)"
+Do not strip TSIG records.
+This option was present but unimplemented until glibc 2.24;
+since glibc 2.25, it is deprecated, and its usage produces a warning.
+.TP
+.BR RES_BLAST " (unimplemented; deprecated in glibc 2.25)"
+Send each query simultaneously and recursively to all servers.
+This option was present but unimplemented until glibc 2.24;
+since glibc 2.25, it is deprecated, and its usage produces a warning.
+.TP
+.BR RES_USEBSTRING " (glibc 2.3.4 to glibc 2.24)"
+Make reverse IPv6 lookups using the bit-label format described in RFC 2673;
+if this option is not set (which is the default), then nibble format is used.
+This option was removed in glibc 2.25,
+since it relied on a backward-incompatible
+DNS extension that was never deployed on the Internet.
+.TP
+.BR RES_NOIP6DOTINT " (glibc 2.24 and earlier)"
+Use
+.I ip6.arpa
+zone in IPv6 reverse lookup instead of
+.IR ip6.int ,
+which is deprecated since glibc 2.3.4.
+This option is present up to and including glibc 2.24,
+where it is enabled by default.
+In glibc 2.25, this option was removed.
+.TP
+.BR RES_USE_EDNS0 " (since glibc 2.6)"
+Enables support for the DNS extensions (EDNS0) described in RFC 2671.
+.TP
+.BR RES_SNGLKUP " (since glibc 2.10)"
+By default, glibc performs IPv4 and IPv6 lookups in parallel
+since glibc 2.9.
+Some appliance DNS servers cannot handle these queries properly
+and make the requests time out.
+This option disables the behavior and makes glibc
+perform the IPv6 and IPv4 requests sequentially
+(at the cost of some slowdown of the resolving process).
+.TP
+.B RES_SNGLKUPREOP
+When
+.B RES_SNGLKUP
+option is enabled, opens a new socket for the each request.
+.TP
+.B RES_USE_DNSSEC
+Use DNSSEC with OK bit in OPT record.
+This option implies
+.BR RES_USE_EDNS0 .
+.TP
+.B RES_NOTLDQUERY
+Do not look up unqualified name as a top-level domain (TLD).
+.TP
+.B RES_DEFAULT
+Default option which implies:
+.BR RES_RECURSE ,
+.BR RES_DEFNAMES ,
+.BR RES_DNSRCH ,
+and
+.BR RES_NOIP6DOTINT .
+.\"
+.SH RETURN VALUE
+The
+.BR res_ninit ()
+and
+.BR res_init ()
+functions return 0 on success, or \-1 if an error
+occurs.
+.P
+The
+.BR res_nquery (),
+.BR res_query (),
+.BR res_nsearch (),
+.BR res_search (),
+.BR res_nquerydomain (),
+.BR res_querydomain (),
+.BR res_nmkquery (),
+.BR res_mkquery (),
+.BR res_nsend (),
+and
+.BR res_send ()
+functions return the length
+of the response, or \-1 if an error occurs.
+.P
+The
+.BR dn_comp ()
+and
+.BR dn_expand ()
+functions return the length
+of the compressed name, or \-1 if an error occurs.
+.P
+In the case of an error return from
+.BR res_nquery (),
+.BR res_query (),
+.BR res_nsearch (),
+.BR res_search (),
+.BR res_nquerydomain (),
+or
+.BR res_querydomain (),
+the global variable
+.I h_errno
+(see
+.BR gethostbyname (3))
+can be consulted to determine the cause of the error.
+.SH FILES
+.TP
+.I /etc/resolv.conf
+resolver configuration file
+.TP
+.I /etc/host.conf
+resolver configuration file
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR res_ninit (),
+.BR res_nclose (),
+.BR res_nquery (),
+.BR res_nsearch (),
+.BR res_nquerydomain (),
+.BR res_nsend ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR res_nmkquery (),
+.BR dn_comp (),
+.BR dn_expand ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD.
+.SH SEE ALSO
+.BR gethostbyname (3),
+.BR resolv.conf (5),
+.BR resolver (5),
+.BR hostname (7),
+.BR named (8)
+.P
+The GNU C library source file
+.IR resolv/README .
diff --git a/man/man3/rewind.3 b/man/man3/rewind.3
new file mode 100644
index 000000000..a1487b5a8
--- /dev/null
+++ b/man/man3/rewind.3
@@ -0,0 +1 @@
+.so man3/fseek.3
diff --git a/man/man3/rewinddir.3 b/man/man3/rewinddir.3
new file mode 100644
index 000000000..5df90c523
--- /dev/null
+++ b/man/man3/rewinddir.3
@@ -0,0 +1,60 @@
+'\" t
+.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:29:11 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 11 June 1995 by Andries Brouwer (aeb@cwi.nl)
+.TH rewinddir 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rewinddir \- reset directory stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.B #include <dirent.h>
+.P
+.BI "void rewinddir(DIR *" dirp );
+.fi
+.SH DESCRIPTION
+The
+.BR rewinddir ()
+function resets the position of the directory
+stream
+.I dirp
+to the beginning of the directory.
+.SH RETURN VALUE
+The
+.BR rewinddir ()
+function returns no value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR rewinddir ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR closedir (3),
+.BR opendir (3),
+.BR readdir (3),
+.BR scandir (3),
+.BR seekdir (3),
+.BR telldir (3)
diff --git a/man/man3/rexec.3 b/man/man3/rexec.3
new file mode 100644
index 000000000..725c71cf8
--- /dev/null
+++ b/man/man3/rexec.3
@@ -0,0 +1,161 @@
+'\" t
+.\" Copyright (c) 1983, 1991, 1993
+.\"     The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)rexec.3     8.1 (Berkeley) 6/4/93
+.\" $FreeBSD: src/lib/libcompat/4.3/rexec.3,v 1.12 2004/07/02 23:52:14 ru Exp $
+.\"
+.\" Taken from FreeBSD 5.4; not checked against Linux reality (mtk)
+.\"
+.\" 2013-06-21, mtk, Converted from mdoc to man macros
+.\"
+.TH rexec 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rexec, rexec_af \- return stream to a remote command
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.B [[deprecated]]
+.BI "int rexec(char **restrict " ahost ", int " inport ,
+.BI "          const char *restrict " user ", const char *restrict " passwd ,
+.BI "          const char *restrict " cmd ", int *restrict " fd2p );
+.P
+.B [[deprecated]]
+.BI "int rexec_af(char **restrict " ahost ", int " inport ,
+.BI "          const char *restrict " user ", const char *restrict " passwd ,
+.BI "          const char *restrict " cmd ", int *restrict " fd2p ,
+.BI "          sa_family_t " af  );
+.fi
+.P
+.BR rexec (),
+.BR rexec_af ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    In glibc up to and including 2.19:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+This interface is obsoleted by
+.BR rcmd (3).
+.P
+The
+.BR rexec ()
+function
+looks up the host
+.I *ahost
+using
+.BR gethostbyname (3),
+returning \-1 if the host does not exist.
+Otherwise,
+.I *ahost
+is set to the standard name of the host.
+If a username and password are both specified, then these
+are used to authenticate to the foreign host; otherwise
+the environment and then the
+.I .netrc
+file in user's
+home directory are searched for appropriate information.
+If all this fails, the user is prompted for the information.
+.P
+The port
+.I inport
+specifies which well-known DARPA Internet port to use for
+the connection; the call
+.I "getservbyname(""exec"", ""tcp"")"
+(see
+.BR getservent (3))
+will return a pointer to a structure that contains the necessary port.
+The protocol for connection is described in detail in
+.BR rexecd (8).
+.P
+If the connection succeeds,
+a socket in the Internet domain of type
+.B SOCK_STREAM
+is returned to
+the caller, and given to the remote command as
+.I stdin
+and
+.IR stdout .
+If
+.I fd2p
+is nonzero, then an auxiliary channel to a control
+process will be setup, and a file descriptor for it will be placed
+in
+.IR *fd2p .
+The control process will return diagnostic
+output from the command (unit 2) on this channel, and will also
+accept bytes on this channel as being UNIX signal numbers, to be
+forwarded to the process group of the command.
+The diagnostic
+information returned does not include remote authorization failure,
+as the secondary connection is set up after authorization has been
+verified.
+If
+.I fd2p
+is 0, then the
+.I stderr
+(unit 2 of the remote
+command) will be made the same as the
+.I stdout
+and no
+provision is made for sending arbitrary signals to the remote process,
+although you may be able to get its attention by using out-of-band data.
+.SS rexec_af()
+The
+.BR rexec ()
+function works over IPv4
+.RB ( AF_INET ).
+By contrast, the
+.BR rexec_af ()
+function provides an extra argument,
+.IR af ,
+that allows the caller to select the protocol.
+This argument can be specified as
+.BR AF_INET ,
+.BR AF_INET6 ,
+or
+.B AF_UNSPEC
+(to allow the implementation to select the protocol).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR rexec (),
+.BR rexec_af ()
+T}	Thread safety	MT-Unsafe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+.TP
+.BR rexec ()
+4.2BSD, BSD, Solaris.
+.TP
+.BR rexec_af ()
+glibc 2.2.
+.SH BUGS
+The
+.BR rexec ()
+function sends the unencrypted password across the network.
+.P
+The underlying service is considered a big security hole and therefore
+not enabled on many sites; see
+.BR rexecd (8)
+for explanations.
+.SH SEE ALSO
+.BR rcmd (3),
+.BR rexecd (8)
diff --git a/man/man3/rexec_af.3 b/man/man3/rexec_af.3
new file mode 100644
index 000000000..517a2d23b
--- /dev/null
+++ b/man/man3/rexec_af.3
@@ -0,0 +1 @@
+.so man3/rexec.3
diff --git a/man/man3/rindex.3 b/man/man3/rindex.3
new file mode 100644
index 000000000..a9cd4b342
--- /dev/null
+++ b/man/man3/rindex.3
@@ -0,0 +1 @@
+.so man3/index.3
diff --git a/man/man3/rint.3 b/man/man3/rint.3
new file mode 100644
index 000000000..262670571
--- /dev/null
+++ b/man/man3/rint.3
@@ -0,0 +1,145 @@
+'\" t
+.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH rint 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl \- round
+to nearest integer
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double nearbyint(double " x );
+.BI "float nearbyintf(float " x );
+.BI "long double nearbyintl(long double " x );
+.P
+.BI "double rint(double " x );
+.BI "float rintf(float " x );
+.BI "long double rintl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR nearbyint (),
+.BR nearbyintf (),
+.BR nearbyintl ():
+.nf
+    _POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE
+.fi
+.P
+.BR rint ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR rintf (),
+.BR rintl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR nearbyint (),
+.BR nearbyintf (),
+and
+.BR nearbyintl ()
+functions round their argument to an integer value in floating-point
+format, using the current rounding direction (see
+.BR fesetround (3))
+and without raising the
+.I inexact
+exception.
+When the current rounding direction is to nearest, these
+functions round halfway cases to the even integer in accordance with
+IEEE-754.
+.P
+The
+.BR rint (),
+.BR rintf (),
+and
+.BR rintl ()
+functions do the same, but will raise the
+.I inexact
+exception
+.RB ( FE_INEXACT ,
+checkable via
+.BR fetestexcept (3))
+when the result differs in value from the argument.
+.SH RETURN VALUE
+These functions return the rounded integer value.
+.P
+If
+.I x
+is integral, +0, \-0, NaN, or infinite,
+.I x
+itself is returned.
+.SH ERRORS
+No errors occur.
+POSIX.1-2001 documents a range error for overflows, but see NOTES.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR nearbyint (),
+.BR nearbyintf (),
+.BR nearbyintl (),
+.BR rint (),
+.BR rintf (),
+.BR rintl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH NOTES
+SUSv2 and POSIX.1-2001 contain text about overflow (which might set
+.I errno
+to
+.BR ERANGE ,
+or raise an
+.B FE_OVERFLOW
+exception).
+In practice, the result cannot overflow on any current machine,
+so this error-handling stuff is just nonsense.
+(More precisely, overflow can happen only when the maximum value
+of the exponent is smaller than the number of mantissa bits.
+For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
+the maximum value of the exponent is 127 (respectively, 1023),
+and the number of mantissa bits
+including the implicit bit
+is 24 (respectively, 53).)
+.P
+If you want to store the rounded value in an integer type,
+you probably want to use one of the functions described in
+.BR lrint (3)
+instead.
+.SH SEE ALSO
+.BR ceil (3),
+.BR floor (3),
+.BR lrint (3),
+.BR round (3),
+.BR trunc (3)
diff --git a/man/man3/rintf.3 b/man/man3/rintf.3
new file mode 100644
index 000000000..3300c2c40
--- /dev/null
+++ b/man/man3/rintf.3
@@ -0,0 +1 @@
+.so man3/rint.3
diff --git a/man/man3/rintl.3 b/man/man3/rintl.3
new file mode 100644
index 000000000..3300c2c40
--- /dev/null
+++ b/man/man3/rintl.3
@@ -0,0 +1 @@
+.so man3/rint.3
diff --git a/man/man3/round.3 b/man/man3/round.3
new file mode 100644
index 000000000..268ec083c
--- /dev/null
+++ b/man/man3/round.3
@@ -0,0 +1,110 @@
+'\" t
+.\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH round 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+round, roundf, roundl \- round to nearest integer, away from zero
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double round(double " x );
+.BI "float roundf(float " x );
+.BI "long double roundl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR round (),
+.BR roundf (),
+.BR roundl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions round
+.I x
+to the nearest integer, but
+round halfway cases away from zero (regardless of the current rounding
+direction, see
+.BR fenv (3)),
+instead of to the nearest even integer like
+.BR rint (3).
+.P
+For example,
+.I round(0.5)
+is 1.0, and
+.I round(\-0.5)
+is \-1.0.
+.SH RETURN VALUE
+These functions return the rounded integer value.
+.P
+If
+.I x
+is integral, +0, \-0, NaN, or infinite,
+.I x
+itself is returned.
+.SH ERRORS
+No errors occur.
+POSIX.1-2001 documents a range error for overflows, but see NOTES.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR round (),
+.BR roundf (),
+.BR roundl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH NOTES
+POSIX.1-2001 contains text about overflow (which might set
+.I errno
+to
+.BR ERANGE ,
+or raise an
+.B FE_OVERFLOW
+exception).
+In practice, the result cannot overflow on any current machine,
+so this error-handling stuff is just nonsense.
+.\" The POSIX.1-2001 APPLICATION USAGE SECTION discusses this point.
+(More precisely, overflow can happen only when the maximum value
+of the exponent is smaller than the number of mantissa bits.
+For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
+the maximum value of the exponent is 127 (respectively, 1023),
+and the number of mantissa bits
+including the implicit bit
+is 24 (respectively, 53).)
+.P
+If you want to store the rounded value in an integer type,
+you probably want to use one of the functions described in
+.BR lround (3)
+instead.
+.SH SEE ALSO
+.BR ceil (3),
+.BR floor (3),
+.BR lround (3),
+.BR nearbyint (3),
+.BR rint (3),
+.BR trunc (3)
diff --git a/man/man3/roundf.3 b/man/man3/roundf.3
new file mode 100644
index 000000000..f7ab38670
--- /dev/null
+++ b/man/man3/roundf.3
@@ -0,0 +1 @@
+.so man3/round.3
diff --git a/man/man3/roundl.3 b/man/man3/roundl.3
new file mode 100644
index 000000000..f7ab38670
--- /dev/null
+++ b/man/man3/roundl.3
@@ -0,0 +1 @@
+.so man3/round.3
diff --git a/man/man3/roundup.3 b/man/man3/roundup.3
new file mode 100644
index 000000000..376591a11
--- /dev/null
+++ b/man/man3/roundup.3
@@ -0,0 +1,56 @@
+.\" Copyright (C) 2023 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH roundup 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+roundup \- round up in steps
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/param.h>
+.P
+.BI roundup( x ", " step );
+.fi
+.SH DESCRIPTION
+This macro rounds
+.I x
+to the nearest multiple of
+.I step
+that is not less than
+.IR x .
+.P
+It is typically used for
+rounding up a pointer to align it or
+increasing a buffer to be allocated.
+.P
+This API is not designed to be generic,
+and doesn't work in some cases
+that are not important for the typical use cases described above.
+See CAVEATS.
+.SH RETURN VALUE
+This macro returns the rounded value.
+.SH STANDARDS
+None.
+.SH CAVEATS
+The arguments may be evaluated more than once.
+.P
+.I x
+should be nonnegative,
+and
+.I step
+should be positive.
+.P
+If
+.I x + step
+would overflow or wrap around,
+the behavior is undefined.
+.SH SEE ALSO
+.BR ceil (3),
+.BR floor (3),
+.BR lrint (3),
+.BR rint (3),
+.BR lround (3),
+.BR round (3)
diff --git a/man/man3/rpc.3 b/man/man3/rpc.3
new file mode 100644
index 000000000..66a97dbeb
--- /dev/null
+++ b/man/man3/rpc.3
@@ -0,0 +1,1201 @@
+'\" t
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\"
+.\" %%%LICENSE_START(BSD_ONELINE_CDROM)
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\" %%%LICENSE_END
+.\"
+.\" @(#)rpc.3n	2.4 88/08/08 4.0 RPCSRC; from 1.19 88/06/24 SMI
+.\"
+.\" 2007-12-30, mtk, Convert function prototypes to modern C syntax
+.\"
+.TH rpc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rpc \- library routines for remote procedure calls
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS AND DESCRIPTION
+These routines allow C programs to make procedure
+calls on other machines across the network.
+First, the client calls a procedure to send a data packet to the server.
+Upon receipt of the packet, the server calls a dispatch routine
+to perform the requested service, and then sends back a reply.
+Finally, the procedure call returns to the client.
+.\" .P
+.\" We don't have an rpc_secure.3 page at the moment -- MTK, 19 Sep 05
+.\" Routines that are used for Secure RPC (DES authentication) are described in
+.\" .BR rpc_secure (3).
+.\" Secure RPC can be used only if DES encryption is available.
+.P
+To take use of these routines, include the header file
+.IR "<rpc/rpc.h>" .
+.P
+The prototypes below make use of the following types:
+.P
+.RS 4
+.EX
+.BI "typedef int " bool_t ;
+.P
+.BI "typedef bool_t (*" xdrproc_t ")(XDR *, void *, ...);"
+.P
+.BI "typedef bool_t (*" resultproc_t ")(caddr_t " resp ,
+.BI "                               struct sockaddr_in *" raddr );
+.EE
+.RE
+.P
+See the header files for the declarations of the
+.IR AUTH ,
+.IR CLIENT ,
+.IR SVCXPRT ,
+and
+.I XDR
+types.
+.P
+.nf
+.BI "void auth_destroy(AUTH *" auth );
+.fi
+.IP
+A macro that destroys the authentication information associated with
+.IR auth .
+Destruction usually involves deallocation of private data structures.
+The use of
+.I auth
+is undefined after calling
+.BR auth_destroy ().
+.P
+.nf
+.B AUTH *authnone_create(void);
+.fi
+.IP
+Create and return an RPC
+authentication handle that passes nonusable authentication
+information with each remote procedure call.
+This is the default authentication used by RPC.
+.P
+.nf
+.BI "AUTH *authunix_create(char *" host ", uid_t " uid ", gid_t " gid ,
+.BI "                      int " len ", gid_t " aup_gids [. len ]);
+.fi
+.IP
+Create and return an RPC authentication handle that contains
+authentication information.
+The parameter
+.I host
+is the name of the machine on which the information was created;
+.I uid
+is the user's user ID;
+.I gid
+is the user's current group ID;
+.I len
+and
+.I aup_gids
+refer to a counted array of groups to which the user belongs.
+It is easy to impersonate a user.
+.P
+.nf
+.B AUTH *authunix_create_default(void);
+.fi
+.IP
+Calls
+.BR authunix_create ()
+with the appropriate parameters.
+.P
+.nf
+.BI "int callrpc(char *" host ", unsigned long " prognum ,
+.BI "            unsigned long " versnum ", unsigned long " procnum ,
+.BI "            xdrproc_t " inproc ", const char *" in ,
+.BI "            xdrproc_t " outproc ", char *" out );
+.fi
+.IP
+Call the remote procedure associated with
+.IR prognum ,
+.IR versnum ,
+and
+.I procnum
+on the machine,
+.IR host .
+The parameter
+.I in
+is the address of the procedure's argument(s), and
+.I out
+is the address of where to place the result(s);
+.I inproc
+is used to encode the procedure's parameters, and
+.I outproc
+is used to decode the procedure's results.
+This routine returns zero if it succeeds, or the value of
+.B "enum clnt_stat"
+cast to an integer if it fails.
+The routine
+.BR clnt_perrno ()
+is handy for translating failure statuses into messages.
+.IP
+Warning: calling remote procedures with this routine
+uses UDP/IP as a transport; see
+.BR clntudp_create ()
+for restrictions.
+You do not have control of timeouts or authentication using this routine.
+.P
+.nf
+.BI "enum clnt_stat clnt_broadcast(unsigned long " prognum ,
+.BI "                     unsigned long " versnum ", unsigned long " procnum ,
+.BI "                     xdrproc_t " inproc ", char *" in ,
+.BI "                     xdrproc_t " outproc ", char *" out ,
+.BI "                     resultproc_t " eachresult );
+.fi
+.IP
+Like
+.BR callrpc (),
+except the call message is broadcast to all locally
+connected broadcast nets.
+Each time it receives a response, this routine calls
+.BR eachresult (),
+whose form is:
+.IP
+.in +4n
+.EX
+.BI "eachresult(char *" out ", struct sockaddr_in *" addr );
+.EE
+.in
+.IP
+where
+.I out
+is the same as
+.I out
+passed to
+.BR clnt_broadcast (),
+except that the remote procedure's output is decoded there;
+.I addr
+points to the address of the machine that sent the results.
+If
+.BR eachresult ()
+returns zero,
+.BR clnt_broadcast ()
+waits for more replies; otherwise it returns with appropriate status.
+.IP
+Warning: broadcast sockets are limited in size to the
+maximum transfer unit of the data link.
+For ethernet, this value is 1500 bytes.
+.P
+.nf
+.BI "enum clnt_stat clnt_call(CLIENT *" clnt ", unsigned long " procnum ,
+.BI "                    xdrproc_t " inproc ", char *" in ,
+.BI "                    xdrproc_t " outproc ", char *" out ,
+.BI "                    struct timeval " tout );
+.fi
+.IP
+A macro that calls the remote procedure
+.I procnum
+associated with the client handle,
+.IR clnt ,
+which is obtained with an RPC client creation routine such as
+.BR clnt_create ().
+The parameter
+.I in
+is the address of the procedure's argument(s), and
+.I out
+is the address of where to place the result(s);
+.I inproc
+is used to encode the procedure's parameters, and
+.I outproc
+is used to decode the procedure's results;
+.I tout
+is the time allowed for results to come back.
+.P
+.nf
+.BI "clnt_destroy(CLIENT *" clnt );
+.fi
+.IP
+A macro that destroys the client's RPC handle.
+Destruction usually involves deallocation
+of private data structures, including
+.I clnt
+itself.
+Use of
+.I clnt
+is undefined after calling
+.BR clnt_destroy ().
+If the RPC library opened the associated socket, it will close it also.
+Otherwise, the socket remains open.
+.P
+.nf
+.BI "CLIENT *clnt_create(const char *" host ", unsigned long " prog ,
+.BI "                    unsigned long " vers ", const char *" proto );
+.fi
+.IP
+Generic client creation routine.
+.I host
+identifies the name of the remote host where the server is located.
+.I proto
+indicates which kind of transport protocol to use.
+The currently supported values for this field are \[lq]udp\[rq]
+and \[lq]tcp\[rq].
+Default timeouts are set, but can be modified using
+.BR clnt_control ().
+.IP
+Warning: using UDP has its shortcomings.
+Since UDP-based RPC messages can hold only up to 8 Kbytes of encoded data,
+this transport cannot be used for procedures that take
+large arguments or return huge results.
+.P
+.nf
+.BI "bool_t clnt_control(CLIENT *" cl ", int " req ", char *" info );
+.fi
+.IP
+A macro used to change or retrieve various information
+about a client object.
+.I req
+indicates the type of operation, and
+.I info
+is a pointer to the information.
+For both UDP and TCP, the supported values of
+.I req
+and their argument types and what they do are:
+.IP
+.in +4n
+.EX
+\fBCLSET_TIMEOUT\fP  \fIstruct timeval\fP // set total timeout
+\fBCLGET_TIMEOUT\fP  \fIstruct timeval\fP // get total timeout
+.EE
+.in
+.IP
+Note: if you set the timeout using
+.BR clnt_control (),
+the timeout parameter passed to
+.BR clnt_call ()
+will be ignored in all future calls.
+.IP
+.in +4n
+.EX
+\fBCLGET_SERVER_ADDR\fP  \fIstruct sockaddr_in\fP
+                // get server\[aq]s address
+.EE
+.in
+.IP
+The following operations are valid for UDP only:
+.IP
+.in +4n
+.EX
+\fBCLSET_RETRY_TIMEOUT\fP  \fIstruct timeval\fP // set the retry timeout
+\fBCLGET_RETRY_TIMEOUT\fP  \fIstruct timeval\fP // get the retry timeout
+.EE
+.in
+.IP
+The retry timeout is the time that "UDP RPC"
+waits for the server to reply before
+retransmitting the request.
+.P
+.nf
+.BI "clnt_freeres(CLIENT * " clnt ", xdrproc_t " outproc ", char *" out );
+.fi
+.IP
+A macro that frees any data allocated by the RPC/XDR
+system when it decoded the results of an RPC call.
+The parameter
+.I out
+is the address of the results, and
+.I outproc
+is the XDR routine describing the results.
+This routine returns one if the results were successfully freed,
+and zero otherwise.
+.P
+.nf
+.BI "void clnt_geterr(CLIENT *" clnt ", struct rpc_err *" errp );
+.fi
+.IP
+A macro that copies the error structure out of the client
+handle to the structure at address
+.IR errp .
+.P
+.nf
+.BI "void clnt_pcreateerror(const char *" s );
+.fi
+.IP
+Print a message to standard error indicating why a client RPC
+handle could not be created.
+The message is prepended with string
+.I s
+and a colon.
+Used when a
+.BR clnt_create (),
+.BR clntraw_create (),
+.BR clnttcp_create (),
+or
+.BR clntudp_create ()
+call fails.
+.P
+.nf
+.BI "void clnt_perrno(enum clnt_stat " stat );
+.fi
+.IP
+Print a message to standard error corresponding
+to the condition indicated by
+.IR stat .
+Used after
+.BR callrpc ().
+.P
+.nf
+.BI "clnt_perror(CLIENT *" clnt ", const char *" s );
+.fi
+.IP
+Print a message to standard error indicating why an RPC call failed;
+.I clnt
+is the handle used to do the call.
+The message is prepended with string
+.I s
+and a colon.
+Used after
+.BR clnt_call ().
+.P
+.nf
+.BI "char *clnt_spcreateerror(const char *" s );
+.fi
+.IP
+Like
+.BR clnt_pcreateerror (),
+except that it returns a string instead of printing to the standard error.
+.IP
+Bugs: returns pointer to static data that is overwritten on each call.
+.P
+.nf
+.BI "char *clnt_sperrno(enum clnt_stat " stat );
+.fi
+.IP
+Take the same arguments as
+.BR clnt_perrno (),
+but instead of sending a message to the standard error indicating why an RPC
+call failed, return a pointer to a string which contains the message.
+The string ends with a NEWLINE.
+.IP
+.BR clnt_sperrno ()
+is used instead of
+.BR clnt_perrno ()
+if the program does not have a standard error (as a program
+running as a server quite likely does not), or if the programmer
+does not want the message to be output with
+.BR printf (3),
+or if a message format different than that supported by
+.BR clnt_perrno ()
+is to be used.
+Note: unlike
+.BR clnt_sperror ()
+and
+.BR clnt_spcreateerror (),
+.BR clnt_sperrno ()
+returns pointer to static data, but the
+result will not get overwritten on each call.
+.P
+.nf
+.BI "char *clnt_sperror(CLIENT *" rpch ", const char *" s );
+.fi
+.IP
+Like
+.BR clnt_perror (),
+except that (like
+.BR clnt_sperrno ())
+it returns a string instead of printing to standard error.
+.IP
+Bugs: returns pointer to static data that is overwritten on each call.
+.P
+.nf
+.BI "CLIENT *clntraw_create(unsigned long " prognum \
+", unsigned long " versnum );
+.fi
+.IP
+This routine creates a toy RPC client for the remote program
+.IR prognum ,
+version
+.IR versnum .
+The transport used to pass messages to the service is
+actually a buffer within the process's address space, so the
+corresponding RPC server should live in the same address space; see
+.BR svcraw_create ().
+This allows simulation of RPC and acquisition of RPC
+overheads, such as round trip times, without any kernel interference.
+This routine returns NULL if it fails.
+.P
+.nf
+.BI "CLIENT *clnttcp_create(struct sockaddr_in *" addr ,
+.BI "                unsigned long " prognum ", unsigned long " versnum ,
+.BI "                int *" sockp ", unsigned int " sendsz \
+", unsigned int " recvsz );
+.fi
+.IP
+This routine creates an RPC client for the remote program
+.IR prognum ,
+version
+.IR versnum ;
+the client uses TCP/IP as a transport.
+The remote program is located at Internet address
+.IR *addr .
+If
+.\"The following inline font conversion is necessary for the hyphen indicator
+.I addr\->sin_port
+is zero, then it is set to the actual port that the remote
+program is listening on (the remote
+.B portmap
+service is consulted for this information).
+The parameter
+.I sockp
+is a socket; if it is
+.BR RPC_ANYSOCK ,
+then this routine opens a new one and sets
+.IR sockp .
+Since TCP-based RPC uses buffered I/O,
+the user may specify the size of the send and receive buffers
+with the parameters
+.I sendsz
+and
+.IR recvsz ;
+values of zero choose suitable defaults.
+This routine returns NULL if it fails.
+.P
+.nf
+.BI "CLIENT *clntudp_create(struct sockaddr_in *" addr ,
+.BI "                unsigned long " prognum ", unsigned long " versnum ,
+.BI "                struct timeval " wait ", int *" sockp );
+.fi
+.IP
+This routine creates an RPC client for the remote program
+.IR prognum ,
+version
+.IR versnum ;
+the client uses use UDP/IP as a transport.
+The remote program is located at Internet address
+.IR addr .
+If
+.I addr\->sin_port
+is zero, then it is set to actual port that the remote
+program is listening on (the remote
+.B portmap
+service is consulted for this information).
+The parameter
+.I sockp
+is a socket; if it is
+.BR RPC_ANYSOCK ,
+then this routine opens a new one and sets
+.IR sockp .
+The UDP transport resends the call message in intervals of
+.I wait
+time until a response is received or until the call times out.
+The total time for the call to time out is specified by
+.BR clnt_call ().
+.IP
+Warning: since UDP-based RPC messages can hold only up to 8 Kbytes
+of encoded data, this transport cannot be used for procedures
+that take large arguments or return huge results.
+.P
+.nf
+.BI "CLIENT *clntudp_bufcreate(struct sockaddr_in *" addr ,
+.BI "            unsigned long " prognum ", unsigned long " versnum ,
+.BI "            struct timeval " wait ", int *" sockp ,
+.BI "            unsigned int " sendsize ", unsigned int "recosize );
+.fi
+.IP
+This routine creates an RPC client for the remote program
+.IR prognum ,
+on
+.IR versnum ;
+the client uses use UDP/IP as a transport.
+The remote program is located at Internet address
+.IR addr .
+If
+.I addr\->sin_port
+is zero, then it is set to actual port that the remote
+program is listening on (the remote
+.B portmap
+service is consulted for this information).
+The parameter
+.I sockp
+is a socket; if it is
+.BR RPC_ANYSOCK ,
+then this routine opens a new one and sets
+.IR sockp .
+The UDP transport resends the call message in intervals of
+.I wait
+time until a response is received or until the call times out.
+The total time for the call to time out is specified by
+.BR clnt_call ().
+.IP
+This allows the user to specify the maximum packet
+size for sending and receiving UDP-based RPC messages.
+.P
+.nf
+.BI "void get_myaddress(struct sockaddr_in *" addr );
+.fi
+.IP
+Stuff the machine's IP address into
+.IR *addr ,
+without consulting the library routines that deal with
+.IR /etc/hosts .
+The port number is always set to
+.BR htons(PMAPPORT) .
+.P
+.nf
+.BI "struct pmaplist *pmap_getmaps(struct sockaddr_in *" addr );
+.fi
+.IP
+A user interface to the
+.B portmap
+service, which returns a list of the current RPC
+program-to-port mappings on the host located at IP address
+.IR *addr .
+This routine can return NULL.
+The command
+.I rpcinfo\~\-p
+uses this routine.
+.P
+.nf
+.BI "unsigned short pmap_getport(struct sockaddr_in *" addr ,
+.BI "                    unsigned long " prognum ", unsigned long " versnum ,
+.BI "                    unsigned int " protocol );
+.fi
+.IP
+A user interface to the
+.B portmap
+service, which returns the port number
+on which waits a service that supports program number
+.IR prognum ,
+version
+.IR versnum ,
+and speaks the transport protocol associated with
+.IR protocol .
+The value of
+.I protocol
+is most likely
+.B IPPROTO_UDP
+or
+.BR IPPROTO_TCP .
+A return value of zero means that the mapping does not exist
+or that the RPC system failed to contact the remote
+.B portmap
+service.
+In the latter case, the global variable
+.I rpc_createerr
+contains the RPC status.
+.P
+.nf
+.BI "enum clnt_stat pmap_rmtcall(struct sockaddr_in *" addr ,
+.BI "                    unsigned long " prognum ", unsigned long " versnum ,
+.BI "                    unsigned long " procnum ,
+.BI "                    xdrproc_t " inproc ", char *" in ,
+.BI "                    xdrproc_t " outproc ", char *" out ,
+.BI "                    struct timeval " tout ", unsigned long *" portp );
+.fi
+.IP
+A user interface to the
+.B portmap
+service, which instructs
+.B portmap
+on the host at IP address
+.I *addr
+to make an RPC call on your behalf to a procedure on that host.
+The parameter
+.I *portp
+will be modified to the program's port number if the procedure succeeds.
+The definitions of other parameters are discussed
+in
+.BR callrpc ()
+and
+.BR clnt_call ().
+This procedure should be used for a \[lq]ping\[rq] and nothing else.
+See also
+.BR clnt_broadcast ().
+.P
+.nf
+.BI "bool_t pmap_set(unsigned long " prognum ", unsigned long " versnum ,
+.BI "                int " protocol ", unsigned short " port );
+.fi
+.IP
+A user interface to the
+.B portmap
+service, which establishes a mapping between the triple
+.RI [ prognum , versnum , protocol ]
+and
+.I port
+on the machine's
+.B portmap
+service.
+The value of
+.I protocol
+is most likely
+.B IPPROTO_UDP
+or
+.BR IPPROTO_TCP .
+This routine returns one if it succeeds, zero otherwise.
+Automatically done by
+.BR svc_register ().
+.P
+.nf
+.BI "bool_t pmap_unset(unsigned long " prognum ", unsigned long " versnum );
+.fi
+.IP
+A user interface to the
+.B portmap
+service, which destroys all mapping between the triple
+.RI [ prognum , versnum , * ]
+and
+.B ports
+on the machine's
+.B portmap
+service.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "int registerrpc(unsigned long " prognum ", unsigned long " versnum ,
+.BI "                unsigned long " procnum ", char *(*" procname ")(char *),"
+.BI "                xdrproc_t " inproc ", xdrproc_t " outproc );
+.fi
+.IP
+Register procedure
+.I procname
+with the RPC service package.
+If a request arrives for program
+.IR prognum ,
+version
+.IR versnum ,
+and procedure
+.IR procnum ,
+.I procname
+is called with a pointer to its parameter(s);
+.I procname
+should return a pointer to its static result(s);
+.I inproc
+is used to decode the parameters while
+.I outproc
+is used to encode the results.
+This routine returns zero if the registration succeeded, \-1 otherwise.
+.IP
+Warning: remote procedures registered in this form
+are accessed using the UDP/IP transport; see
+.BR svcudp_create ()
+for restrictions.
+.P
+.nf
+.BI "struct rpc_createerr " rpc_createerr ;
+.fi
+.IP
+A global variable whose value is set by any RPC client creation routine
+that does not succeed.
+Use the routine
+.BR clnt_pcreateerror ()
+to print the reason why.
+.P
+.nf
+.BI "void svc_destroy(SVCXPRT *" xprt );
+.fi
+.IP
+A macro that destroys the RPC service transport handle,
+.IR xprt .
+Destruction usually involves deallocation
+of private data structures, including
+.I xprt
+itself.
+Use of
+.I xprt
+is undefined after calling this routine.
+.P
+.nf
+.BI "fd_set " svc_fdset ;
+.fi
+.IP
+A global variable reflecting the RPC service side's
+read file descriptor bit mask; it is suitable as a parameter to the
+.BR select (2)
+system call.
+This is of interest only if a service implementor does their own
+asynchronous event processing, instead of calling
+.BR svc_run ().
+This variable is read-only (do not pass its address to
+.BR select (2)!),
+yet it may change after calls to
+.BR svc_getreqset ()
+or any creation routines.
+.P
+.nf
+.BI "int " svc_fds ;
+.fi
+.IP
+Similar to
+.BR svc_fdset ,
+but limited to 32 file descriptors.
+This interface is obsoleted by
+.BR svc_fdset .
+.P
+.nf
+.BI "svc_freeargs(SVCXPRT *" xprt ", xdrproc_t " inproc ", char *" in );
+.fi
+.IP
+A macro that frees any data allocated by the RPC/XDR
+system when it decoded the arguments to a service procedure using
+.BR svc_getargs ().
+This routine returns 1 if the results were successfully freed,
+and zero otherwise.
+.P
+.nf
+.BI "svc_getargs(SVCXPRT *" xprt ", xdrproc_t " inproc ", char *" in );
+.fi
+.IP
+A macro that decodes the arguments of an RPC request
+associated with the RPC service transport handle,
+.IR xprt .
+The parameter
+.I in
+is the address where the arguments will be placed;
+.I inproc
+is the XDR routine used to decode the arguments.
+This routine returns one if decoding succeeds, and zero otherwise.
+.P
+.nf
+.BI "struct sockaddr_in *svc_getcaller(SVCXPRT *" xprt );
+.fi
+.IP
+The approved way of getting the network address of the caller
+of a procedure associated with the RPC service transport handle,
+.IR xprt .
+.P
+.nf
+.BI "void svc_getreqset(fd_set *" rdfds );
+.fi
+.IP
+This routine is of interest only if a service implementor does not call
+.BR svc_run (),
+but instead implements custom asynchronous event processing.
+It is called when the
+.BR select (2)
+system call has determined that an RPC request has arrived on some
+RPC socket(s);
+.I rdfds
+is the resultant read file descriptor bit mask.
+The routine returns when all sockets associated with the value of
+.I rdfds
+have been serviced.
+.P
+.nf
+.BI "void svc_getreq(int " rdfds );
+.fi
+.IP
+Similar to
+.BR svc_getreqset (),
+but limited to 32 file descriptors.
+This interface is obsoleted by
+.BR svc_getreqset ().
+.P
+.nf
+.BI "bool_t svc_register(SVCXPRT *" xprt ", unsigned long " prognum ,
+.BI "                    unsigned long " versnum ,
+.BI "                    void (*" dispatch ")(struct svc_req *, SVCXPRT *),"
+.BI "                    unsigned long " protocol );
+.fi
+.IP
+Associates
+.I prognum
+and
+.I versnum
+with the service dispatch procedure,
+.IR dispatch .
+If
+.I protocol
+is zero, the service is not registered with the
+.B portmap
+service.
+If
+.I protocol
+is nonzero, then a mapping of the triple
+.RI [ prognum , versnum , protocol ]
+to
+.I xprt\->xp_port
+is established with the local
+.B portmap
+service (generally
+.I protocol
+is zero,
+.B IPPROTO_UDP
+or
+.BR IPPROTO_TCP ).
+The procedure
+.I dispatch
+has the following form:
+.IP
+.in +4n
+.EX
+dispatch(struct svc_req *request, SVCXPRT *xprt);
+.EE
+.in
+.IP
+The
+.BR svc_register ()
+routine returns one if it succeeds, and zero otherwise.
+.P
+.nf
+.B "void svc_run(void);"
+.fi
+.IP
+This routine never returns.
+It waits for RPC requests to arrive, and calls the appropriate service
+procedure using
+.BR svc_getreq ()
+when one arrives.
+This procedure is usually waiting for a
+.BR select (2)
+system call to return.
+.P
+.nf
+.BI "bool_t svc_sendreply(SVCXPRT *" xprt ", xdrproc_t " outproc \
+", char *" out );
+.fi
+.IP
+Called by an RPC service's dispatch routine to send the results of a
+remote procedure call.
+The parameter
+.I xprt
+is the request's associated transport handle;
+.I outproc
+is the XDR routine which is used to encode the results; and
+.I out
+is the address of the results.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "void svc_unregister(unsigned long " prognum ", unsigned long " versnum );
+.fi
+.IP
+Remove all mapping of the double
+.RI [ prognum , versnum ]
+to dispatch routines, and of the triple
+.RI [ prognum , versnum , * ]
+to port number.
+.P
+.nf
+.BI "void svcerr_auth(SVCXPRT *" xprt ", enum auth_stat " why );
+.fi
+.IP
+Called by a service dispatch routine that refuses to perform
+a remote procedure call due to an authentication error.
+.P
+.nf
+.BI "void svcerr_decode(SVCXPRT *" xprt );
+.fi
+.IP
+Called by a service dispatch routine that cannot successfully
+decode its parameters.
+See also
+.BR svc_getargs ().
+.P
+.nf
+.BI "void svcerr_noproc(SVCXPRT *" xprt );
+.fi
+.IP
+Called by a service dispatch routine that does not implement
+the procedure number that the caller requests.
+.P
+.nf
+.BI "void svcerr_noprog(SVCXPRT *" xprt );
+.fi
+.IP
+Called when the desired program is not registered with the RPC package.
+Service implementors usually do not need this routine.
+.P
+.nf
+.BI "void svcerr_progvers(SVCXPRT *" xprt ", unsigned long " low_vers ,
+.BI "                     unsigned long " high_vers );
+.fi
+.IP
+Called when the desired version of a program is not registered
+with the RPC package.
+Service implementors usually do not need this routine.
+.P
+.nf
+.BI "void svcerr_systemerr(SVCXPRT *" xprt );
+.fi
+.IP
+Called by a service dispatch routine when it detects a system
+error not covered by any particular protocol.
+For example, if a service can no longer allocate storage,
+it may call this routine.
+.P
+.nf
+.BI "void svcerr_weakauth(SVCXPRT *" xprt );
+.fi
+.IP
+Called by a service dispatch routine that refuses to perform
+a remote procedure call due to insufficient authentication parameters.
+The routine calls
+.BR "svcerr_auth(xprt, AUTH_TOOWEAK)" .
+.P
+.nf
+.BI "SVCXPRT *svcfd_create(int " fd ", unsigned int " sendsize ,
+.BI "                      unsigned int " recvsize );
+.fi
+.IP
+Create a service on top of any open file descriptor.
+Typically, this file descriptor is a connected socket for a stream protocol such
+as TCP.
+.I sendsize
+and
+.I recvsize
+indicate sizes for the send and receive buffers.
+If they are zero, a reasonable default is chosen.
+.P
+.nf
+.B SVCXPRT *svcraw_create(void);
+.fi
+.IP
+This routine creates a toy RPC
+service transport, to which it returns a pointer.
+The transport is really a buffer within the process's address space,
+so the corresponding RPC client should live in the same address space; see
+.BR clntraw_create ().
+This routine allows simulation of RPC and acquisition of RPC
+overheads (such as round trip times), without any kernel interference.
+This routine returns NULL if it fails.
+.P
+.nf
+.BI "SVCXPRT *svctcp_create(int " sock ", unsigned int " send_buf_size ,
+.BI "                       unsigned int " recv_buf_size );
+.fi
+.IP
+This routine creates a TCP/IP-based RPC
+service transport, to which it returns a pointer.
+The transport is associated with the socket
+.IR sock ,
+which may be
+.BR RPC_ANYSOCK ,
+in which case a new socket is created.
+If the socket is not bound to a local TCP
+port, then this routine binds it to an arbitrary port.
+Upon completion,
+.I xprt\->xp_sock
+is the transport's socket descriptor, and
+.I xprt\->xp_port
+is the transport's port number.
+This routine returns NULL if it fails.
+Since TCP-based RPC uses buffered I/O,
+users may specify the size of buffers; values of zero
+choose suitable defaults.
+.P
+.nf
+.BI "SVCXPRT *svcudp_bufcreate(int " sock ", unsigned int " sendsize ,
+.BI "                          unsigned int " recosize );
+.fi
+.IP
+This routine creates a UDP/IP-based RPC
+service transport, to which it returns a pointer.
+The transport is associated with the socket
+.IR sock ,
+which may be
+.BR RPC_ANYSOCK ,
+in which case a new socket is created.
+If the socket is not bound to a local UDP
+port, then this routine binds it to an arbitrary port.
+Upon completion,
+.I xprt\->xp_sock
+is the transport's socket descriptor, and
+.I xprt\->xp_port
+is the transport's port number.
+This routine returns NULL if it fails.
+.IP
+This allows the user to specify the maximum packet size for sending and
+receiving UDP-based RPC messages.
+.P
+.nf
+.BI "SVCXPRT *svcudp_create(int " sock );
+.fi
+.IP
+This call is equivalent to
+.I svcudp_bufcreate(sock,SZ,SZ)
+for some default size
+.IR SZ .
+.P
+.nf
+.BI "bool_t xdr_accepted_reply(XDR *" xdrs ", struct accepted_reply *" ar );
+.fi
+.IP
+Used for encoding RPC reply messages.
+This routine is useful for users who wish to generate
+RPC-style messages without using the RPC package.
+.P
+.nf
+.BI "bool_t xdr_authunix_parms(XDR *" xdrs ", struct authunix_parms *" aupp );
+.fi
+.IP
+Used for describing UNIX credentials.
+This routine is useful for users
+who wish to generate these credentials without using the RPC
+authentication package.
+.P
+.nf
+.BI "void xdr_callhdr(XDR *" xdrs ", struct rpc_msg *" chdr );
+.fi
+.IP
+Used for describing RPC call header messages.
+This routine is useful for users who wish to generate
+RPC-style messages without using the RPC package.
+.P
+.nf
+.BI "bool_t xdr_callmsg(XDR *" xdrs ", struct rpc_msg *" cmsg );
+.fi
+.IP
+Used for describing RPC call messages.
+This routine is useful for users who wish to generate RPC-style
+messages without using the RPC package.
+.P
+.nf
+.BI "bool_t xdr_opaque_auth(XDR *" xdrs ", struct opaque_auth *" ap );
+.fi
+.IP
+Used for describing RPC authentication information messages.
+This routine is useful for users who wish to generate
+RPC-style messages without using the RPC package.
+.P
+.nf
+.BI "bool_t xdr_pmap(XDR *" xdrs ", struct pmap *" regs );
+.fi
+.IP
+Used for describing parameters to various
+.B portmap
+procedures, externally.
+This routine is useful for users who wish to generate
+these parameters without using the
+.B pmap
+interface.
+.P
+.nf
+.BI "bool_t xdr_pmaplist(XDR *" xdrs ", struct pmaplist **" rp );
+.fi
+.IP
+Used for describing a list of port mappings, externally.
+This routine is useful for users who wish to generate
+these parameters without using the
+.B pmap
+interface.
+.P
+.nf
+.BI "bool_t xdr_rejected_reply(XDR *" xdrs ", struct rejected_reply *" rr );
+.fi
+.IP
+Used for describing RPC reply messages.
+This routine is useful for users who wish to generate
+RPC-style messages without using the RPC package.
+.P
+.nf
+.BI "bool_t xdr_replymsg(XDR *" xdrs ", struct rpc_msg *" rmsg );
+.fi
+.IP
+Used for describing RPC reply messages.
+This routine is useful for users who wish to generate
+RPC style messages without using the RPC package.
+.P
+.nf
+.BI "void xprt_register(SVCXPRT *" xprt );
+.fi
+.IP
+After RPC service transport handles are created,
+they should register themselves with the RPC service package.
+This routine modifies the global variable
+.IR svc_fds .
+Service implementors usually do not need this routine.
+.P
+.nf
+.BI "void xprt_unregister(SVCXPRT *" xprt );
+.fi
+.IP
+Before an RPC service transport handle is destroyed,
+it should unregister itself with the RPC service package.
+This routine modifies the global variable
+.IR svc_fds .
+Service implementors usually do not need this routine.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR auth_destroy (),
+.BR authnone_create (),
+.BR authunix_create (),
+.BR authunix_create_default (),
+.BR callrpc (),
+.BR clnt_broadcast (),
+.BR clnt_call (),
+.BR clnt_destroy (),
+.BR clnt_create (),
+.BR clnt_control (),
+.BR clnt_freeres (),
+.BR clnt_geterr (),
+.BR clnt_pcreateerror (),
+.BR clnt_perrno (),
+.BR clnt_perror (),
+.BR clnt_spcreateerror (),
+.BR clnt_sperrno (),
+.BR clnt_sperror (),
+.BR clntraw_create (),
+.BR clnttcp_create (),
+.BR clntudp_create (),
+.BR clntudp_bufcreate (),
+.BR get_myaddress (),
+.BR pmap_getmaps (),
+.BR pmap_getport (),
+.BR pmap_rmtcall (),
+.BR pmap_set (),
+.BR pmap_unset (),
+.BR registerrpc (),
+.BR svc_destroy (),
+.BR svc_freeargs (),
+.BR svc_getargs (),
+.BR svc_getcaller (),
+.BR svc_getreqset (),
+.BR svc_getreq (),
+.BR svc_register (),
+.BR svc_run (),
+.BR svc_sendreply (),
+.BR svc_unregister (),
+.BR svcerr_auth (),
+.BR svcerr_decode (),
+.BR svcerr_noproc (),
+.BR svcerr_noprog (),
+.BR svcerr_progvers (),
+.BR svcerr_systemerr (),
+.BR svcerr_weakauth (),
+.BR svcfd_create (),
+.BR svcraw_create (),
+.BR svctcp_create (),
+.BR svcudp_bufcreate (),
+.BR svcudp_create (),
+.BR xdr_accepted_reply (),
+.BR xdr_authunix_parms (),
+.BR xdr_callhdr (),
+.BR xdr_callmsg (),
+.BR xdr_opaque_auth (),
+.BR xdr_pmap (),
+.BR xdr_pmaplist (),
+.BR xdr_rejected_reply (),
+.BR xdr_replymsg (),
+.BR xprt_register (),
+.BR xprt_unregister ()
+T}	Thread safety	MT-Safe
+.TE
+.SH SEE ALSO
+.\" We don't have an rpc_secure.3 page in the set at the moment -- MTK, 19 Sep 05
+.\" .BR rpc_secure (3),
+.BR xdr (3)
+.P
+The following manuals:
+.RS
+Remote Procedure Calls: Protocol Specification
+.br
+Remote Procedure Call Programming Guide
+.br
+rpcgen Programming Guide
+.br
+.RE
+.P
+.IR "RPC: Remote Procedure Call Protocol Specification" ,
+RFC\ 1050, Sun Microsystems, Inc.,
+USC-ISI.
diff --git a/man/man3/rpmatch.3 b/man/man3/rpmatch.3
new file mode 100644
index 000000000..fd285cc64
--- /dev/null
+++ b/man/man3/rpmatch.3
@@ -0,0 +1,169 @@
+'\" t
+.\" Copyright (C) 2006 Justin Pryzby <pryzbyj@justinpryzby.com>
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Permission is hereby granted, free of charge, to any person obtaining
+.\" a copy of this software and associated documentation files (the
+.\" "Software"), to deal in the Software without restriction, including
+.\" without limitation the rights to use, copy, modify, merge, publish,
+.\" distribute, sublicense, and/or sell copies of the Software, and to
+.\" permit persons to whom the Software is furnished to do so, subject to
+.\" the following conditions:
+.\"
+.\" The above copyright notice and this permission notice shall be
+.\" included in all copies or substantial portions of the Software.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+.\" IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+.\" CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+.\" TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+.\" SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+.\" %%%LICENSE_END
+.\"
+.\" References:
+.\"   glibc manual and source
+.\"
+.\" 2006-05-19, mtk, various edits and example program
+.\"
+.TH rpmatch 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rpmatch \- determine if the answer to a question is affirmative or negative
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int rpmatch(const char *" response );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR rpmatch ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+.BR rpmatch ()
+handles a user response to yes or no questions, with
+support for internationalization.
+.P
+.I response
+should be a null-terminated string containing a
+user-supplied response, perhaps obtained with
+.BR fgets (3)
+or
+.BR getline (3).
+.P
+The user's language preference is taken into account per the
+environment variables
+.BR LANG ,
+.BR LC_MESSAGES ,
+and
+.BR LC_ALL ,
+if the program has called
+.BR setlocale (3)
+to effect their changes.
+.P
+Regardless of the locale, responses matching
+.B \[ha][Yy]
+are always accepted as affirmative, and those matching
+.B \[ha][Nn]
+are always accepted as negative.
+.SH RETURN VALUE
+After examining
+.IR response ,
+.BR rpmatch ()
+returns 0 for a recognized negative response ("no"), 1
+for a recognized positive response ("yes"), and \-1 when the value
+of
+.I response
+is unrecognized.
+.SH ERRORS
+A return value of \-1 may indicate either an invalid input, or some
+other error.
+It is incorrect to only test if the return value is nonzero.
+.P
+.BR rpmatch ()
+can fail for any of the reasons that
+.BR regcomp (3)
+or
+.BR regexec (3)
+can fail; the cause of the error
+is not available from
+.I errno
+or anywhere else, but indicates a
+failure of the regex engine (but this case is indistinguishable from
+that of an unrecognized value of
+.IR response ).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR rpmatch ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+GNU, FreeBSD, AIX.
+.SH BUGS
+The
+.BR YESEXPR " and " NOEXPR
+of some locales (including "C") only inspect the first character of the
+.IR response .
+This can mean that "yno" et al. resolve to
+.BR 1 .
+This is an unfortunate historical side-effect which should be fixed in time
+with proper localisation, and should not deter from
+.BR rpmatch ()
+being the proper way to distinguish between binary answers.
+.SH EXAMPLES
+The following program displays the results when
+.BR rpmatch ()
+is applied to the string given in the program's command-line argument.
+.P
+.\" SRC BEGIN (rpmatch.c)
+.EX
+#define _DEFAULT_SOURCE
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    if (argc != 2 || strcmp(argv[1], "\-\-help") == 0) {
+        fprintf(stderr, "%s response\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    setlocale(LC_ALL, "");
+    printf("rpmatch() returns: %d\en", rpmatch(argv[1]));
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fgets (3),
+.BR getline (3),
+.BR nl_langinfo (3),
+.BR regcomp (3),
+.BR setlocale (3)
diff --git a/man/man3/rresvport.3 b/man/man3/rresvport.3
new file mode 100644
index 000000000..b58efefab
--- /dev/null
+++ b/man/man3/rresvport.3
@@ -0,0 +1 @@
+.so man3/rcmd.3
diff --git a/man/man3/rresvport_af.3 b/man/man3/rresvport_af.3
new file mode 100644
index 000000000..b58efefab
--- /dev/null
+++ b/man/man3/rresvport_af.3
@@ -0,0 +1 @@
+.so man3/rcmd.3
diff --git a/man/man3/rtime.3 b/man/man3/rtime.3
new file mode 100644
index 000000000..cac162ed2
--- /dev/null
+++ b/man/man3/rtime.3
@@ -0,0 +1,152 @@
+'\" t
+.\" Copyright 2003 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Modified 2003-04-04 Walter Harms
+.\" <walter.harms@informatik.uni-oldenburg.de>
+.\"
+.\" Slightly polished, aeb, 2003-04-06
+.\"
+.TH rtime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rtime \- get time from a remote machine
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <rpc/auth_des.h>"
+.P
+.BI "int rtime(struct sockaddr_in *" addrp ", struct rpc_timeval *" timep ,
+.BI "          struct rpc_timeval *" timeout );
+.fi
+.SH DESCRIPTION
+This function uses the Time Server Protocol as described in
+RFC\ 868 to obtain the time from a remote machine.
+.P
+The Time Server Protocol gives the time in seconds since
+00:00:00 UTC, 1 Jan 1900,
+and this function subtracts the appropriate constant in order to
+convert the result to seconds since the
+Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.P
+When
+.I timeout
+is non-NULL, the udp/time socket (port 37) is used.
+Otherwise, the tcp/time socket (port 37) is used.
+.SH RETURN VALUE
+On success, 0 is returned, and the obtained 32-bit time value is stored in
+.IR timep\->tv_sec .
+In case of error \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+All errors for underlying functions
+.RB ( sendto (2),
+.BR poll (2),
+.BR recvfrom (2),
+.BR connect (2),
+.BR read (2))
+can occur.
+Moreover:
+.TP
+.B EIO
+The number of returned bytes is not 4.
+.TP
+.B ETIMEDOUT
+The waiting time as defined in timeout has expired.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR rtime ()
+T}	Thread safety	MT-Safe
+.TE
+.SH NOTES
+Only IPv4 is supported.
+.P
+Some
+.I in.timed
+versions support only TCP.
+Try the example program with
+.I use_tcp
+set to 1.
+.\" .P
+.\" Libc5 uses the prototype
+.\" .P
+.\" .nf
+.\"    int rtime(struct sockaddr_in *, struct timeval *, struct timeval *);
+.\" .fi
+.\" .P
+.\" and requires
+.\" .I <sys/time.h>
+.\" instead of
+.\" .IR <rpc/auth_des.h> .
+.SH BUGS
+.BR rtime ()
+in glibc 2.2.5 and earlier does not work properly on 64-bit machines.
+.SH EXAMPLES
+This example requires that port 37 is up and open.
+You may check
+that the time entry within
+.I /etc/inetd.conf
+is not commented out.
+.P
+The program connects to a computer called "linux".
+Using "localhost" does not work.
+The result is the localtime of the computer "linux".
+.P
+.\" SRC BEGIN (rtime.c)
+.EX
+#include <errno.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+\&
+#include <rpc/auth_des.h>
+\&
+static int use_tcp = 0;
+static const char servername[] = "linux";
+\&
+int
+main(void)
+{
+    int                 ret;
+    time_t              t;
+    struct hostent      *hent;
+    struct rpc_timeval  time1 = {0, 0};
+    struct rpc_timeval  timeout = {1, 0};
+    struct sockaddr_in  name;
+\&
+    memset(&name, 0, sizeof(name));
+    sethostent(1);
+    hent = gethostbyname(servername);
+    memcpy(&name.sin_addr, hent\->h_addr, hent\->h_length);
+\&
+    ret = rtime(&name, &time1, use_tcp ? NULL : &timeout);
+    if (ret < 0)
+        perror("rtime error");
+    else {
+        t = time1.tv_sec;
+        printf("%s\en", ctime(&t));
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.\" .BR netdate (1),
+.BR ntpdate (1),
+.\" .BR rdate (1),
+.BR inetd (8)
diff --git a/man/man3/rtnetlink.3 b/man/man3/rtnetlink.3
new file mode 100644
index 000000000..6be783eaf
--- /dev/null
+++ b/man/man3/rtnetlink.3
@@ -0,0 +1,122 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: rtnetlink.3,v 1.2 1999/05/18 10:35:10 freitag Exp $
+.\"
+.TH rtnetlink 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rtnetlink \- macros to manipulate rtnetlink messages
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <asm/types.h>
+.B #include <linux/netlink.h>
+.B #include <linux/rtnetlink.h>
+.B #include <sys/socket.h>
+.P
+.BI "rtnetlink_socket = socket(AF_NETLINK, int " socket_type \
+", NETLINK_ROUTE);"
+.P
+.BI "int RTA_OK(struct rtattr *" rta ", int " rtabuflen );
+.P
+.BI "void *RTA_DATA(struct rtattr *" rta );
+.BI "unsigned int RTA_PAYLOAD(struct rtattr *" rta );
+.P
+.BI "struct rtattr *RTA_NEXT(struct rtattr *" rta \
+", unsigned int " rtabuflen );
+.P
+.BI "unsigned int RTA_LENGTH(unsigned int " length );
+.BI "unsigned int RTA_SPACE(unsigned int "length );
+.fi
+.SH DESCRIPTION
+All
+.BR rtnetlink (7)
+messages consist of a
+.BR netlink (7)
+message header and appended attributes.
+The attributes should be manipulated only using the macros provided here.
+.P
+.BI RTA_OK( rta ", " attrlen )
+returns true if
+.I rta
+points to a valid routing attribute;
+.I attrlen
+is the running length of the attribute buffer.
+When not true then you must assume there are no more attributes in the
+message, even if
+.I attrlen
+is nonzero.
+.P
+.BI RTA_DATA( rta )
+returns a pointer to the start of this attribute's data.
+.P
+.BI RTA_PAYLOAD( rta )
+returns the length of this attribute's data.
+.P
+.BI RTA_NEXT( rta ", " attrlen )
+gets the next attribute after
+.IR rta .
+Calling this macro will update
+.IR attrlen .
+You should use
+.B RTA_OK
+to check the validity of the returned pointer.
+.P
+.BI RTA_LENGTH( len )
+returns the length which is required for
+.I len
+bytes of data plus the header.
+.P
+.BI RTA_SPACE( len )
+returns the amount of space which will be needed in a message with
+.I len
+bytes of data.
+.SH STANDARDS
+Linux.
+.SH BUGS
+This manual page is incomplete.
+.SH EXAMPLES
+.\" FIXME . ? would be better to use libnetlink in the EXAMPLE code here
+Creating a rtnetlink message to set the MTU of a device:
+.P
+.in +4n
+.EX
+#include <linux/rtnetlink.h>
+\&
+\&...
+\&
+struct {
+    struct nlmsghdr  nh;
+    struct ifinfomsg if;
+    char             attrbuf[512];
+} req;
+\&
+struct rtattr *rta;
+unsigned int mtu = 1000;
+\&
+int rtnetlink_sk = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
+\&
+memset(&req, 0, sizeof(req));
+req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(req.if));
+req.nh.nlmsg_flags = NLM_F_REQUEST;
+req.nh.nlmsg_type = RTM_NEWLINK;
+req.if.ifi_family = AF_UNSPEC;
+req.if.ifi_index = INTERFACE_INDEX;
+req.if.ifi_change = 0xffffffff; /* ??? */
+rta = (struct rtattr *)(((char *) &req) +
+                         NLMSG_ALIGN(req.nh.nlmsg_len));
+rta\->rta_type = IFLA_MTU;
+rta\->rta_len = RTA_LENGTH(sizeof(mtu));
+req.nh.nlmsg_len = NLMSG_ALIGN(req.nh.nlmsg_len) +
+                              RTA_LENGTH(sizeof(mtu));
+memcpy(RTA_DATA(rta), &mtu, sizeof(mtu));
+send(rtnetlink_sk, &req, req.nh.nlmsg_len, 0);
+.EE
+.in
+.SH SEE ALSO
+.BR netlink (3),
+.BR netlink (7),
+.BR rtnetlink (7)
diff --git a/man/man3/ruserok.3 b/man/man3/ruserok.3
new file mode 100644
index 000000000..b58efefab
--- /dev/null
+++ b/man/man3/ruserok.3
@@ -0,0 +1 @@
+.so man3/rcmd.3
diff --git a/man/man3/ruserok_af.3 b/man/man3/ruserok_af.3
new file mode 100644
index 000000000..b58efefab
--- /dev/null
+++ b/man/man3/ruserok_af.3
@@ -0,0 +1 @@
+.so man3/rcmd.3
diff --git a/man/man3/scalb.3 b/man/man3/scalb.3
new file mode 100644
index 000000000..b3cc8c2c9
--- /dev/null
+++ b/man/man3/scalb.3
@@ -0,0 +1,196 @@
+'\" t
+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH scalb 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+scalb, scalbf, scalbl \- multiply floating-point number
+by integral power of radix (OBSOLETE)
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "[[deprecated]] double scalb(double " x ", double " exp );
+.BI "[[deprecated]] float scalbf(float " x ", float " exp );
+.BI "[[deprecated]] long double scalbl(long double " x ", long double " exp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR scalb ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR scalbf (),
+.BR scalbl ():
+.nf
+    _XOPEN_SOURCE >= 600
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions multiply their first argument
+.I x
+by
+.B FLT_RADIX
+(probably 2)
+to the power of
+.IR exp ,
+that is:
+.P
+.nf
+    x * FLT_RADIX ** exp
+.fi
+.P
+The definition of
+.B FLT_RADIX
+can be obtained by including
+.IR <float.h> .
+.\" not in /usr/include but in a gcc lib
+.SH RETURN VALUE
+On success, these functions return
+.I x
+*
+.B FLT_RADIX
+**
+.IR exp .
+.P
+If
+.I x
+or
+.I exp
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity),
+and
+.I exp
+is not negative infinity,
+positive infinity (negative infinity) is returned.
+.P
+If
+.I x
+is +0 (\-0), and
+.I exp
+is not positive infinity, +0 (\-0) is returned.
+.P
+If
+.I x
+is zero, and
+.I exp
+is positive infinity,
+a domain error occurs, and
+a NaN is returned.
+.P
+If
+.I x
+is an infinity,
+and
+.I exp
+is negative infinity,
+a domain error occurs, and
+a NaN is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with a sign the same as
+.IR x .
+.P
+If the result underflows,
+a range error occurs,
+and the functions return zero, with a sign the same as
+.IR x .
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is 0, and \fIexp\fP is positive infinity, \
+or \fIx\fP is positive infinity and \fIexp\fP is negative infinity \
+and the other argument is not a NaN
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Range error, overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error, underflow
+.I errno
+is set to
+.BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR scalb (),
+.BR scalbf (),
+.BR scalbl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+.TP
+.BR scalb ()
+4.3BSD.
+Obsolescent in POSIX.1-2001;
+Removed in POSIX.1-2008,
+recommending the use of
+.BR scalbln (3),
+.BR scalblnf (3),
+or
+.BR scalblnl (3)
+instead.
+.\" Looking at header files: scalbf() is present on the
+.\" BSDs, Tru64, HP-UX 11, Irix 6.5; scalbl() is on HP-UX 11 and Tru64.
+.SH BUGS
+Before glibc 2.20,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6803
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6804
+these functions did not set
+.I errno
+for domain and range errors.
+.SH SEE ALSO
+.BR ldexp (3),
+.BR scalbln (3)
diff --git a/man/man3/scalbf.3 b/man/man3/scalbf.3
new file mode 100644
index 000000000..5a33fb820
--- /dev/null
+++ b/man/man3/scalbf.3
@@ -0,0 +1 @@
+.so man3/scalb.3
diff --git a/man/man3/scalbl.3 b/man/man3/scalbl.3
new file mode 100644
index 000000000..5a33fb820
--- /dev/null
+++ b/man/man3/scalbl.3
@@ -0,0 +1 @@
+.so man3/scalb.3
diff --git a/man/man3/scalbln.3 b/man/man3/scalbln.3
new file mode 100644
index 000000000..bedf5dbf8
--- /dev/null
+++ b/man/man3/scalbln.3
@@ -0,0 +1,174 @@
+'\" t
+.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH scalbln 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl \-
+multiply floating-point number by integral power of radix
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double scalbln(double " x ", long " exp );
+.BI "float scalblnf(float " x ", long " exp );
+.BI "long double scalblnl(long double " x ", long " exp );
+.P
+.BI "double scalbn(double " x ", int " exp );
+.BI "float scalbnf(float " x ", int " exp );
+.BI "long double scalbnl(long double " x ", int " exp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR scalbln (),
+.BR scalblnf (),
+.BR scalblnl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+.fi
+.P
+.BR scalbn (),
+.BR scalbnf (),
+.BR scalbnl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions multiply their first argument
+.I x
+by
+.B FLT_RADIX
+(probably 2)
+to the power of
+.IR exp ,
+that is:
+.P
+.nf
+    x * FLT_RADIX ** exp
+.fi
+.P
+The definition of
+.B FLT_RADIX
+can be obtained by including
+.IR <float.h> .
+.\" not in /usr/include but in a gcc lib
+.SH RETURN VALUE
+On success, these functions return
+.I x
+*
+.B FLT_RADIX
+**
+.IR exp .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity),
+positive infinity (negative infinity) is returned.
+.P
+If
+.I x
+is +0 (\-0), +0 (\-0) is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with a sign the same as
+.IR x .
+.P
+If the result underflows,
+a range error occurs,
+and the functions return zero, with a sign the same as
+.IR x .
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error, overflow
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.TP
+Range error, underflow
+.I errno
+is set to
+.BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR scalbn (),
+.BR scalbnf (),
+.BR scalbnl (),
+.BR scalbln (),
+.BR scalblnf (),
+.BR scalblnl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH HISTORY
+These functions differ from the obsolete functions described in
+.BR scalb (3)
+in the type of their second argument.
+The functions described on this page have a second argument
+of an integral type, while those in
+.BR scalb (3)
+have a second argument of type
+.IR double .
+.SH NOTES
+If
+.B FLT_RADIX
+equals 2 (which is usual), then
+.BR scalbn ()
+is equivalent to
+.BR ldexp (3).
+.SH BUGS
+Before glibc 2.20,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6803
+these functions did not set
+.I errno
+for range errors.
+.SH SEE ALSO
+.BR ldexp (3),
+.BR scalb (3)
diff --git a/man/man3/scalblnf.3 b/man/man3/scalblnf.3
new file mode 100644
index 000000000..58d82f2d5
--- /dev/null
+++ b/man/man3/scalblnf.3
@@ -0,0 +1 @@
+.so man3/scalbln.3
diff --git a/man/man3/scalblnl.3 b/man/man3/scalblnl.3
new file mode 100644
index 000000000..58d82f2d5
--- /dev/null
+++ b/man/man3/scalblnl.3
@@ -0,0 +1 @@
+.so man3/scalbln.3
diff --git a/man/man3/scalbn.3 b/man/man3/scalbn.3
new file mode 100644
index 000000000..58d82f2d5
--- /dev/null
+++ b/man/man3/scalbn.3
@@ -0,0 +1 @@
+.so man3/scalbln.3
diff --git a/man/man3/scalbnf.3 b/man/man3/scalbnf.3
new file mode 100644
index 000000000..58d82f2d5
--- /dev/null
+++ b/man/man3/scalbnf.3
@@ -0,0 +1 @@
+.so man3/scalbln.3
diff --git a/man/man3/scalbnl.3 b/man/man3/scalbnl.3
new file mode 100644
index 000000000..58d82f2d5
--- /dev/null
+++ b/man/man3/scalbnl.3
@@ -0,0 +1 @@
+.so man3/scalbln.3
diff --git a/man/man3/scandir.3 b/man/man3/scandir.3
new file mode 100644
index 000000000..8ec405e3a
--- /dev/null
+++ b/man/man3/scandir.3
@@ -0,0 +1,310 @@
+'\" t
+.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:26:16 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Thu Apr 11 17:11:33 1996 by Andries Brouwer (aeb@cwi.nl):
+.\"     Corrected type of compar routines, as suggested by
+.\"     Miguel Barreiro (enano@avalon.yaix.es).  Added example.
+.\" Modified Sun Sep 24 20:15:46 2000 by aeb, following Petter Reinholdtsen.
+.\" Modified 2001-12-26 by aeb, following Joey. Added versionsort.
+.\"
+.\" The pieces on scandirat(3) were copyright and licensed as follows.
+.\"
+.\" Copyright (c) 2012, Mark R. Bannister <cambridge@users.sourceforge.net>
+.\"        based on text in mkfifoat.3 Copyright (c) 2006, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH scandir 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+scandir, scandirat, alphasort, versionsort \- scan
+a directory for matching entries
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <dirent.h>
+.P
+.BI "int scandir(const char *restrict " dirp ,
+.BI "            struct dirent ***restrict " namelist ,
+.BI "            int (*" filter ")(const struct dirent *),"
+.BI "            int (*" compar ")(const struct dirent **,"
+.B "                          const struct dirent **));"
+.P
+.BI "int alphasort(const struct dirent **" a ", const struct dirent **" b );
+.BI "int versionsort(const struct dirent **" a ", const struct dirent **" b );
+.P
+.BR "#include <fcntl.h>" "          /* Definition of AT_* constants */"
+.B #include <dirent.h>
+.P
+.BI "int scandirat(int " dirfd ", const char *restrict " dirp ,
+.BI "            struct dirent ***restrict " namelist ,
+.BI "            int (*" filter ")(const struct dirent *),"
+.BI "            int (*" compar ")(const struct dirent **,"
+.B "                          const struct dirent **));"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR scandir (),
+.BR alphasort ():
+.nf
+    /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR versionsort ():
+.nf
+    _GNU_SOURCE
+.fi
+.P
+.BR scandirat ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR scandir ()
+function scans the directory \fIdirp\fP, calling
+\fIfilter\fP() on each directory entry.
+Entries for which
+\fIfilter\fP() returns nonzero are stored in strings allocated via
+.BR malloc (3),
+sorted using
+.BR qsort (3)
+with the comparison
+function \fIcompar\fP(), and collected in array \fInamelist\fP
+which is allocated via
+.BR malloc (3).
+If \fIfilter\fP is NULL, all entries are selected.
+.P
+The
+.BR alphasort ()
+and
+.BR versionsort ()
+functions can be used as the comparison function
+.IR compar ().
+The former sorts directory entries using
+.BR strcoll (3),
+the latter using
+.BR strverscmp (3)
+on the strings \fI(*a)\->d_name\fP and \fI(*b)\->d_name\fP.
+.SS scandirat()
+The
+.BR scandirat ()
+function operates in exactly the same way as
+.BR scandir (),
+except for the differences described here.
+.P
+If the pathname given in
+.I dirp
+is relative, then it is interpreted relative to the directory
+referred to by the file descriptor
+.I dirfd
+(rather than relative to the current working directory of
+the calling process, as is done by
+.BR scandir ()
+for a relative pathname).
+.P
+If
+.I dirp
+is relative and
+.I dirfd
+is the special value
+.BR AT_FDCWD ,
+then
+.I dirp
+is interpreted relative to the current working
+directory of the calling process (like
+.BR scandir ()).
+.P
+If
+.I dirp
+is absolute, then
+.I dirfd
+is ignored.
+.P
+See
+.BR openat (2)
+for an explanation of the need for
+.BR scandirat ().
+.SH RETURN VALUE
+The
+.BR scandir ()
+function returns the number of directory entries
+selected.
+On error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.P
+The
+.BR alphasort ()
+and
+.BR versionsort ()
+functions return an integer less than, equal to,
+or greater than zero if the first argument is considered to be
+respectively less than, equal to, or greater than the second.
+.SH ERRORS
+.TP
+.B EBADF
+.RB ( scandirat ())
+.I dirp
+is relative but
+.I dirfd
+is neither
+.B AT_FDCWD
+nor a valid file descriptor.
+.TP
+.B ENOENT
+The path in \fIdirp\fR does not exist.
+.TP
+.B ENOMEM
+Insufficient memory to complete the operation.
+.TP
+.B ENOTDIR
+The path in \fIdirp\fR is not a directory.
+.TP
+.B ENOTDIR
+.RB ( scandirat ())
+.I dirp
+is a relative pathname and
+.I dirfd
+is a file descriptor referring to a file other than a directory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR scandir (),
+.BR scandirat ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR alphasort (),
+.BR versionsort ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+.TP
+.BR alphasort ()
+.TQ
+.BR scandir ()
+POSIX.1-2008.
+.TP
+.BR versionsort ()
+.TQ
+.BR scandirat ()
+GNU.
+.SH HISTORY
+.TP
+.BR alphasort ()
+.TQ
+.BR scandir ()
+4.3BSD, POSIX.1-2008.
+.TP
+.BR versionsort ()
+glibc 2.1.
+.TP
+.BR scandirat ()
+glibc 2.15.
+.\" .P
+.\" The functions
+.\" .BR scandir ()
+.\" and
+.\" .BR alphasort ()
+.\" are from 4.3BSD, and have been available under Linux since libc4.
+.\" Libc4 and libc5 use the more precise prototype
+.\" .sp
+.\" .nf
+.\"    int alphasort(const struct dirent ** a,
+.\"                  const struct dirent **b);
+.\" .fi
+.\" .sp
+.\" but glibc 2.0 returns to the imprecise BSD prototype.
+.SH NOTES
+Since glibc 2.1,
+.BR alphasort ()
+calls
+.BR strcoll (3);
+earlier it used
+.BR strcmp (3).
+.P
+Before glibc 2.10, the two arguments of
+.BR alphasort ()
+and
+.BR versionsort ()
+were typed as
+.IR "const void\ *" .
+When
+.BR alphasort ()
+was standardized in POSIX.1-2008,
+the argument type was specified as the type-safe
+.IR "const struct dirent\ **",
+and glibc 2.10 changed the definition of
+.BR alphasort ()
+(and the nonstandard
+.BR versionsort ())
+to match the standard.
+.SH EXAMPLES
+The program below prints a list of the files in the current directory
+in reverse order.
+.\"
+.SS Program source
+\&
+.\" SRC BEGIN (scandir.c)
+.EX
+#define _DEFAULT_SOURCE
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    struct dirent **namelist;
+    int n;
+\&
+    n = scandir(".", &namelist, NULL, alphasort);
+    if (n == \-1) {
+        perror("scandir");
+        exit(EXIT_FAILURE);
+    }
+\&
+    while (n\-\-) {
+        printf("%s\en", namelist[n]\->d_name);
+        free(namelist[n]);
+    }
+    free(namelist);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR closedir (3),
+.BR fnmatch (3),
+.BR opendir (3),
+.BR readdir (3),
+.BR rewinddir (3),
+.BR seekdir (3),
+.BR strcmp (3),
+.BR strcoll (3),
+.BR strverscmp (3),
+.BR telldir (3)
diff --git a/man/man3/scandirat.3 b/man/man3/scandirat.3
new file mode 100644
index 000000000..7e757c7a0
--- /dev/null
+++ b/man/man3/scandirat.3
@@ -0,0 +1 @@
+.so man3/scandir.3
diff --git a/man/man3/scanf.3 b/man/man3/scanf.3
new file mode 100644
index 000000000..be335a597
--- /dev/null
+++ b/man/man3/scanf.3
@@ -0,0 +1,159 @@
+'\" t
+.\" Copyright 2022 Alejandro Colomar <alx@kernel.org>
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH scanf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+scanf, fscanf, vscanf, vfscanf \- input FILE format conversion
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int scanf(const char *restrict " format ", ...);"
+.BI "int fscanf(FILE *restrict " stream ,
+.BI "           const char *restrict " format ", ...);"
+.P
+.B #include <stdarg.h>
+.P
+.BI "int vscanf(const char *restrict " format ", va_list " ap );
+.BI "int vfscanf(FILE *restrict " stream ,
+.BI "           const char *restrict " format ", va_list " ap );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR vscanf (),
+.BR vfscanf ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR scanf ()
+family of functions scans formatted input like
+.BR sscanf (3),
+but read from a
+.IR FILE .
+It is very difficult to use these functions correctly,
+and it is preferable to read entire lines with
+.BR fgets (3)
+or
+.BR getline (3)
+and parse them later with
+.BR sscanf (3)
+or more specialized functions such as
+.BR strtol (3).
+.P
+The
+.BR scanf ()
+function reads input from the standard input stream
+.I stdin
+and
+.BR fscanf ()
+reads input from the stream pointer
+.IR stream .
+.P
+The
+.BR vfscanf ()
+function is analogous to
+.BR vfprintf (3)
+and reads input from the stream pointer
+.I stream
+using a variable argument list of pointers (see
+.BR stdarg (3).
+The
+.BR vscanf ()
+function is analogous to
+.BR vprintf (3)
+and reads from the standard input.
+.SH RETURN VALUE
+On success, these functions return the number of input items
+successfully matched and assigned;
+this can be fewer than provided for,
+or even zero, in the event of an early matching failure.
+.P
+The value
+.B EOF
+is returned if the end of input is reached before either the first
+successful conversion or a matching failure occurs.
+.B EOF
+is also returned if a read error occurs,
+in which case the error indicator for the stream (see
+.BR ferror (3))
+is set, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The file descriptor underlying
+.I stream
+is marked nonblocking, and the read operation would block.
+.TP
+.B EBADF
+The file descriptor underlying
+.I stream
+is invalid, or not open for reading.
+.TP
+.B EILSEQ
+Input byte sequence does not form a valid character.
+.TP
+.B EINTR
+The read operation was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EINVAL
+Not enough arguments; or
+.I format
+is NULL.
+.TP
+.B ENOMEM
+Out of memory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR scanf (),
+.BR fscanf (),
+.BR vscanf (),
+.BR vfscanf ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH CAVEATS
+These functions make it difficult to
+distinguish newlines from other white space,
+This is especially problematic with line-buffered input,
+like the standard input stream.
+.P
+These functions can't report errors after the last
+non-suppressed conversion specification.
+.SH BUGS
+It is impossible to accurately know
+how many characters these functions have consumed from the input stream,
+since they only report the number of successful conversions.
+For example,
+if the input is "123\en\ a",
+.I scanf(\[dq]%d\ %d\[dq], &a, &b)
+will consume the digits, the newline, and the space, but not the letter a.
+This makes it difficult to recover from invalid input.
+.SH SEE ALSO
+.BR fgets (3),
+.BR getline (3),
+.BR sscanf (3)
diff --git a/man/man3/sched_getcpu.3 b/man/man3/sched_getcpu.3
new file mode 100644
index 000000000..f45d80054
--- /dev/null
+++ b/man/man3/sched_getcpu.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sched_getcpu 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched_getcpu \- determine CPU on which the calling thread is running
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sched.h>
+.P
+.B int sched_getcpu(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sched_getcpu ():
+.nf
+    Since glibc 2.14:
+        _GNU_SOURCE
+    Before glibc 2.14:
+        _BSD_SOURCE || _SVID_SOURCE
+            /* _GNU_SOURCE also suffices */
+.fi
+.SH DESCRIPTION
+.BR sched_getcpu ()
+returns the number of the CPU
+on which the calling thread is currently executing.
+.SH RETURN VALUE
+On success,
+.BR sched_getcpu ()
+returns a nonnegative CPU number.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOSYS
+This kernel does not implement
+.BR getcpu (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sched_getcpu ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.6.
+.SH NOTES
+The call
+.P
+.in +4n
+.EX
+cpu = sched_getcpu();
+.EE
+.in
+.P
+is equivalent to the following
+.BR getcpu (2)
+call:
+.P
+.in +4n
+.EX
+int c, s;
+s = getcpu(&c, NULL);
+cpu = (s == \-1) ? s : c;
+.EE
+.in
+.SH SEE ALSO
+.BR getcpu (2),
+.BR sched (7)
diff --git a/man/man3/secure_getenv.3 b/man/man3/secure_getenv.3
new file mode 100644
index 000000000..5142befad
--- /dev/null
+++ b/man/man3/secure_getenv.3
@@ -0,0 +1 @@
+.so man3/getenv.3
diff --git a/man/man3/seed48.3 b/man/man3/seed48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/seed48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/seed48_r.3 b/man/man3/seed48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/seed48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/seekdir.3 b/man/man3/seekdir.3
new file mode 100644
index 000000000..ceb5850b2
--- /dev/null
+++ b/man/man3/seekdir.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:25:21 1993 by Rik Faith (faith@cs.unc.edu)
+.\"
+.TH seekdir 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+seekdir \- set the position of the next readdir() call in the directory
+stream.
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <dirent.h>
+.P
+.BI "void seekdir(DIR *" dirp ", long " loc );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR seekdir ():
+.nf
+    _XOPEN_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR seekdir ()
+function sets the location in the directory stream
+from which the next
+.BR readdir (2)
+call will start.
+The
+.I loc
+argument should be a value returned by a previous call to
+.BR telldir (3).
+.SH RETURN VALUE
+The
+.BR seekdir ()
+function returns no value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR seekdir ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.SH CAVEATS
+Up to glibc 2.1.1, the type of the
+.I loc
+argument was
+.IR off_t .
+POSIX.1-2001 specifies
+.IR long ,
+and this is the type used since glibc 2.1.2.
+See
+.BR telldir (3)
+for information on why you should be careful in making any
+assumptions about the value in this argument.
+.SH SEE ALSO
+.BR lseek (2),
+.BR closedir (3),
+.BR opendir (3),
+.BR readdir (3),
+.BR rewinddir (3),
+.BR scandir (3),
+.BR telldir (3)
diff --git a/man/man3/sem_close.3 b/man/man3/sem_close.3
new file mode 100644
index 000000000..da7c45d03
--- /dev/null
+++ b/man/man3/sem_close.3
@@ -0,0 +1,63 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_close 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_close \- close a named semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_close(sem_t *" sem );
+.fi
+.SH DESCRIPTION
+.BR sem_close ()
+closes the named semaphore referred to by
+.IR sem ,
+allowing any resources that the system has allocated to
+the calling process for this semaphore to be freed.
+.SH RETURN VALUE
+On success
+.BR sem_close ()
+returns 0; on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I sem
+is not a valid semaphore.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_close ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+All open named semaphores are automatically closed on process
+termination, or upon
+.BR execve (2).
+.SH SEE ALSO
+.BR sem_getvalue (3),
+.BR sem_open (3),
+.BR sem_post (3),
+.BR sem_unlink (3),
+.BR sem_wait (3),
+.BR sem_overview (7)
diff --git a/man/man3/sem_destroy.3 b/man/man3/sem_destroy.3
new file mode 100644
index 000000000..0a8d0d2e7
--- /dev/null
+++ b/man/man3/sem_destroy.3
@@ -0,0 +1,75 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_destroy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_destroy \- destroy an unnamed semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_destroy(sem_t *" sem );
+.fi
+.SH DESCRIPTION
+.BR sem_destroy ()
+destroys the unnamed semaphore at the address pointed to by
+.IR sem .
+.P
+Only a semaphore that has been initialized by
+.BR sem_init (3)
+should be destroyed using
+.BR sem_destroy ().
+.P
+Destroying a semaphore that other processes or threads are
+currently blocked on (in
+.BR sem_wait (3))
+produces undefined behavior.
+.P
+Using a semaphore that has been destroyed produces undefined results,
+until the semaphore has been reinitialized using
+.BR sem_init (3).
+.SH RETURN VALUE
+.BR sem_destroy ()
+returns 0 on success;
+on error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I sem
+is not a valid semaphore.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_destroy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+An unnamed semaphore should be destroyed with
+.BR sem_destroy ()
+before the memory in which it is located is deallocated.
+Failure to do this can result in resource leaks on some implementations.
+.\" But not on NPTL, where sem_destroy () is a no-op..
+.SH SEE ALSO
+.BR sem_init (3),
+.BR sem_post (3),
+.BR sem_wait (3),
+.BR sem_overview (7)
diff --git a/man/man3/sem_getvalue.3 b/man/man3/sem_getvalue.3
new file mode 100644
index 000000000..5ee09648f
--- /dev/null
+++ b/man/man3/sem_getvalue.3
@@ -0,0 +1,74 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_getvalue 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_getvalue \- get the value of a semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_getvalue(sem_t *restrict " sem ", int *restrict " sval );
+.fi
+.SH DESCRIPTION
+.BR sem_getvalue ()
+places the current value of the semaphore pointed to
+.I sem
+into the integer pointed to by
+.IR sval .
+.P
+If one or more processes or threads are blocked
+waiting to lock the semaphore with
+.BR sem_wait (3),
+POSIX.1 permits two possibilities for the value returned in
+.IR sval :
+either 0 is returned;
+or a negative number whose absolute value is the count
+of the number of processes and threads currently blocked in
+.BR sem_wait (3).
+Linux adopts the former behavior.
+.SH RETURN VALUE
+.BR sem_getvalue ()
+returns 0 on success;
+on error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I sem
+is not a valid semaphore.
+(The glibc implementation currently does not check whether
+.I sem
+is valid.)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_getvalue ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The value of the semaphore may already have changed by the time
+.BR sem_getvalue ()
+returns.
+.SH SEE ALSO
+.BR sem_post (3),
+.BR sem_wait (3),
+.BR sem_overview (7)
diff --git a/man/man3/sem_init.3 b/man/man3/sem_init.3
new file mode 100644
index 000000000..7b46e8e7f
--- /dev/null
+++ b/man/man3/sem_init.3
@@ -0,0 +1,108 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_init 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_init \- initialize an unnamed semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_init(sem_t *" sem ", int " pshared ", unsigned int " value );
+.fi
+.SH DESCRIPTION
+.BR sem_init ()
+initializes the unnamed semaphore at the address pointed to by
+.IR sem .
+The
+.I value
+argument specifies the initial value for the semaphore.
+.P
+The
+.I pshared
+argument indicates whether this semaphore is to be shared
+between the threads of a process, or between processes.
+.P
+If
+.I pshared
+has the value 0,
+then the semaphore is shared between the threads of a process,
+and should be located at some address that is visible to all threads
+(e.g., a global variable, or a variable allocated dynamically on
+the heap).
+.P
+If
+.I pshared
+is nonzero, then the semaphore is shared between processes,
+and should be located in a region of shared memory (see
+.BR shm_open (3),
+.BR mmap (2),
+and
+.BR shmget (2)).
+(Since a child created by
+.BR fork (2)
+inherits its parent's memory mappings, it can also access the semaphore.)
+Any process that can access the shared memory region
+can operate on the semaphore using
+.BR sem_post (3),
+.BR sem_wait (3),
+and so on.
+.P
+Initializing a semaphore that has already been initialized
+results in undefined behavior.
+.SH RETURN VALUE
+.BR sem_init ()
+returns 0 on success;
+on error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I value
+exceeds
+.BR SEM_VALUE_MAX .
+.TP
+.B ENOSYS
+.I pshared
+is nonzero,
+but the system does not support process-shared semaphores (see
+.BR sem_overview (7)).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_init ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Bizarrely, POSIX.1-2001 does not specify the value that should
+be returned by a successful call to
+.BR sem_init ().
+POSIX.1-2008 rectifies this, specifying the zero return on success.
+.SH EXAMPLES
+See
+.BR shm_open (3)
+and
+.BR sem_wait (3).
+.SH SEE ALSO
+.BR sem_destroy (3),
+.BR sem_post (3),
+.BR sem_wait (3),
+.BR sem_overview (7)
diff --git a/man/man3/sem_open.3 b/man/man3/sem_open.3
new file mode 100644
index 000000000..814997b72
--- /dev/null
+++ b/man/man3/sem_open.3
@@ -0,0 +1,175 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_open 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_open \- initialize and open a named semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.BR "#include <fcntl.h>" "           /* For O_* constants */"
+.BR "#include <sys/stat.h>" "        /* For mode constants */"
+.B #include <semaphore.h>
+.P
+.BI "sem_t *sem_open(const char *" name ", int " oflag );
+.BI "sem_t *sem_open(const char *" name ", int " oflag ,
+.BI "                mode_t " mode ", unsigned int " value );
+.fi
+.SH DESCRIPTION
+.BR sem_open ()
+creates a new POSIX semaphore or opens an existing semaphore.
+The semaphore is identified by
+.IR name .
+For details of the construction of
+.IR name ,
+see
+.BR sem_overview (7).
+.P
+The
+.I oflag
+argument specifies flags that control the operation of the call.
+(Definitions of the flags values can be obtained by including
+.IR <fcntl.h> .)
+If
+.B O_CREAT
+is specified in
+.IR oflag ,
+then the semaphore is created if
+it does not already exist.
+The owner (user ID) of the semaphore is set to the effective
+user ID of the calling process.
+The group ownership (group ID) is set to the effective group ID
+of the calling process.
+.\" In reality the filesystem IDs are used on Linux.
+If both
+.B O_CREAT
+and
+.B O_EXCL
+are specified in
+.IR oflag ,
+then an error is returned if a semaphore with the given
+.I name
+already exists.
+.P
+If
+.B O_CREAT
+is specified in
+.IR oflag ,
+then two additional arguments must be supplied.
+The
+.I mode
+argument specifies the permissions to be placed on the new semaphore,
+as for
+.BR open (2).
+(Symbolic definitions for the permissions bits can be obtained by including
+.IR <sys/stat.h> .)
+The permissions settings are masked against the process umask.
+Both read and write permission should be granted to each class of
+user that will access the semaphore.
+The
+.I value
+argument specifies the initial value for the new semaphore.
+If
+.B O_CREAT
+is specified, and a semaphore with the given
+.I name
+already exists, then
+.I mode
+and
+.I value
+are ignored.
+.SH RETURN VALUE
+On success,
+.BR sem_open ()
+returns the address of the new semaphore;
+this address is used when calling other semaphore-related functions.
+On error,
+.BR sem_open ()
+returns
+.BR SEM_FAILED ,
+with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The semaphore exists, but the caller does not have permission to
+open it.
+.TP
+.B EEXIST
+Both
+.B O_CREAT
+and
+.B O_EXCL
+were specified in
+.IR oflag ,
+but a semaphore with this
+.I name
+already exists.
+.TP
+.B EINVAL
+.I value
+was greater than
+.BR SEM_VALUE_MAX .
+.TP
+.B EINVAL
+.I name
+consists of just "/", followed by no other characters.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENAMETOOLONG
+.I name
+was too long.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+The
+.B O_CREAT
+flag was not specified in
+.I oflag
+and no semaphore with this
+.I name
+exists;
+or,
+.\" this error can occur if we have a name of the (nonportable) form
+.\" /dir/name, and the directory /dev/shm/dir does not exist.
+.B O_CREAT
+was specified, but
+.I name
+wasn't well formed.
+.TP
+.B ENOMEM
+Insufficient memory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_open ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR sem_close (3),
+.BR sem_getvalue (3),
+.BR sem_post (3),
+.BR sem_unlink (3),
+.BR sem_wait (3),
+.BR sem_overview (7)
diff --git a/man/man3/sem_post.3 b/man/man3/sem_post.3
new file mode 100644
index 000000000..1f9222e0d
--- /dev/null
+++ b/man/man3/sem_post.3
@@ -0,0 +1,73 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_post 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_post \- unlock a semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_post(sem_t *" sem );
+.fi
+.SH DESCRIPTION
+.BR sem_post ()
+increments (unlocks) the semaphore pointed to by
+.IR sem .
+If the semaphore's value consequently becomes greater than zero,
+then another process or thread blocked in a
+.BR sem_wait (3)
+call will be woken up and proceed to lock the semaphore.
+.SH RETURN VALUE
+.BR sem_post ()
+returns 0 on success;
+on error, the value of the semaphore is left unchanged,
+\-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I sem
+is not a valid semaphore.
+.TP
+.B EOVERFLOW
+.\" Added in POSIX.1-2008 TC1 (Austin Interpretation 213)
+The maximum allowable value for a semaphore would be exceeded.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_post ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+.BR sem_post ()
+is async-signal-safe:
+it may be safely called within a signal handler.
+.SH EXAMPLES
+See
+.BR sem_wait (3)
+and
+.BR shm_open (3).
+.SH SEE ALSO
+.BR sem_getvalue (3),
+.BR sem_wait (3),
+.BR sem_overview (7),
+.BR signal\-safety (7)
diff --git a/man/man3/sem_timedwait.3 b/man/man3/sem_timedwait.3
new file mode 100644
index 000000000..c7b43fa88
--- /dev/null
+++ b/man/man3/sem_timedwait.3
@@ -0,0 +1 @@
+.so man3/sem_wait.3
diff --git a/man/man3/sem_trywait.3 b/man/man3/sem_trywait.3
new file mode 100644
index 000000000..c7b43fa88
--- /dev/null
+++ b/man/man3/sem_trywait.3
@@ -0,0 +1 @@
+.so man3/sem_wait.3
diff --git a/man/man3/sem_unlink.3 b/man/man3/sem_unlink.3
new file mode 100644
index 000000000..1f442e108
--- /dev/null
+++ b/man/man3/sem_unlink.3
@@ -0,0 +1,66 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_unlink 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_unlink \- remove a named semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_unlink(const char *" name );
+.fi
+.SH DESCRIPTION
+.BR sem_unlink ()
+removes the named semaphore referred to by
+.IR name .
+The semaphore name is removed immediately.
+The semaphore is destroyed once all other processes that have
+the semaphore open close it.
+.SH RETURN VALUE
+On success
+.BR sem_unlink ()
+returns 0; on error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+The caller does not have permission to unlink this semaphore.
+.TP
+.B ENAMETOOLONG
+.I name
+was too long.
+.TP
+.B ENOENT
+There is no semaphore with the given
+.IR name .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_unlink ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR sem_getvalue (3),
+.BR sem_open (3),
+.BR sem_post (3),
+.BR sem_wait (3),
+.BR sem_overview (7)
diff --git a/man/man3/sem_wait.3 b/man/man3/sem_wait.3
new file mode 100644
index 000000000..8d31e2f2a
--- /dev/null
+++ b/man/man3/sem_wait.3
@@ -0,0 +1,251 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_wait 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_wait, sem_timedwait, sem_trywait \- lock a semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_wait(sem_t *" sem );
+.BI "int sem_trywait(sem_t *" sem );
+.BI "int sem_timedwait(sem_t *restrict " sem ,
+.BI "                  const struct timespec *restrict " abs_timeout );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sem_timedwait ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.BR sem_wait ()
+decrements (locks) the semaphore pointed to by
+.IR sem .
+If the semaphore's value is greater than zero,
+then the decrement proceeds, and the function returns, immediately.
+If the semaphore currently has the value zero,
+then the call blocks until either it becomes possible to perform
+the decrement (i.e., the semaphore value rises above zero),
+or a signal handler interrupts the call.
+.P
+.BR sem_trywait ()
+is the same as
+.BR sem_wait (),
+except that if the decrement cannot be immediately performed,
+then call returns an error
+.RI ( errno
+set to
+.BR EAGAIN )
+instead of blocking.
+.P
+.BR sem_timedwait ()
+is the same as
+.BR sem_wait (),
+except that
+.I abs_timeout
+specifies a limit on the amount of time that the call
+should block if the decrement cannot be immediately performed.
+The
+.I abs_timeout
+argument points to a
+.BR timespec (3)
+structure that specifies an absolute timeout
+in seconds and nanoseconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.P
+If the timeout has already expired by the time of the call,
+and the semaphore could not be locked immediately,
+then
+.BR sem_timedwait ()
+fails with a timeout error
+.RI ( errno
+set to
+.BR ETIMEDOUT ).
+.P
+If the operation can be performed immediately, then
+.BR sem_timedwait ()
+never fails with a timeout error, regardless of the value of
+.IR abs_timeout .
+Furthermore, the validity of
+.I abs_timeout
+is not checked in this case.
+.SH RETURN VALUE
+All of these functions return 0 on success;
+on error, the value of the semaphore is left unchanged,
+\-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+.RB ( sem_trywait ())
+The operation could not be performed without blocking (i.e., the
+semaphore currently has the value zero).
+.TP
+.B EINTR
+The call was interrupted by a signal handler; see
+.BR signal (7).
+.TP
+.B EINVAL
+.I sem
+is not a valid semaphore.
+.TP
+.B EINVAL
+.RB ( sem_timedwait ())
+The value of
+.I abs_timeout.tv_nsecs
+is less than 0, or greater than or equal to 1000 million.
+.TP
+.B ETIMEDOUT
+.RB ( sem_timedwait ())
+The call timed out before the semaphore could be locked.
+.\" POSIX.1-2001 also allows EDEADLK -- "A deadlock condition
+.\" was detected", but this does not occur on Linux(?).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sem_wait (),
+.BR sem_trywait (),
+.BR sem_timedwait ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+The (somewhat trivial) program shown below operates on an
+unnamed semaphore.
+The program expects two command-line arguments.
+The first argument specifies a seconds value that is used to
+set an alarm timer to generate a
+.B SIGALRM
+signal.
+This handler performs a
+.BR sem_post (3)
+to increment the semaphore that is being waited on in
+.I main()
+using
+.BR sem_timedwait ().
+The second command-line argument specifies the length
+of the timeout, in seconds, for
+.BR sem_timedwait ().
+The following shows what happens on two different runs of the program:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 2 3"
+About to call sem_timedwait()
+sem_post() from handler
+sem_timedwait() succeeded
+.RB "$" " ./a.out 2 1"
+About to call sem_timedwait()
+sem_timedwait() timed out
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (sem_wait.c)
+.EX
+#include <errno.h>
+#include <semaphore.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+\&
+#include <assert.h>
+\&
+sem_t sem;
+\&
+#define handle_error(msg) \e
+    do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+static void
+handler(int sig)
+{
+    write(STDOUT_FILENO, "sem_post() from handler\en", 24);
+    if (sem_post(&sem) == \-1) {
+        write(STDERR_FILENO, "sem_post() failed\en", 18);
+        _exit(EXIT_FAILURE);
+    }
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    struct sigaction sa;
+    struct timespec ts;
+    int s;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <alarm\-secs> <wait\-secs>\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (sem_init(&sem, 0, 0) == \-1)
+        handle_error("sem_init");
+\&
+    /* Establish SIGALRM handler; set alarm timer using argv[1]. */
+\&
+    sa.sa_handler = handler;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = 0;
+    if (sigaction(SIGALRM, &sa, NULL) == \-1)
+        handle_error("sigaction");
+\&
+    alarm(atoi(argv[1]));
+\&
+    /* Calculate relative interval as current time plus
+       number of seconds given argv[2]. */
+\&
+    if (clock_gettime(CLOCK_REALTIME, &ts) == \-1)
+        handle_error("clock_gettime");
+\&
+    ts.tv_sec += atoi(argv[2]);
+\&
+    printf("%s() about to call sem_timedwait()\en", __func__);
+    while ((s = sem_timedwait(&sem, &ts)) == \-1 && errno == EINTR)
+        continue;       /* Restart if interrupted by handler. */
+\&
+    /* Check what happened. */
+\&
+    if (s == \-1) {
+        if (errno == ETIMEDOUT)
+            printf("sem_timedwait() timed out\en");
+        else
+            perror("sem_timedwait");
+    } else
+        printf("sem_timedwait() succeeded\en");
+\&
+    exit((s == 0) ? EXIT_SUCCESS : EXIT_FAILURE);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR sem_getvalue (3),
+.BR sem_post (3),
+.BR timespec (3),
+.BR sem_overview (7),
+.BR time (7)
diff --git a/man/man3/setaliasent.3 b/man/man3/setaliasent.3
new file mode 100644
index 000000000..24d162751
--- /dev/null
+++ b/man/man3/setaliasent.3
@@ -0,0 +1,184 @@
+'\" t
+.\" Copyright 2003 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Polished a bit, added a little, aeb
+.\"
+.TH setaliasent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setaliasent, endaliasent, getaliasent, getaliasent_r,
+getaliasbyname, getaliasbyname_r \- read an alias entry
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <aliases.h>
+.P
+.B "void setaliasent(void);"
+.B "void endaliasent(void);"
+.P
+.B "struct aliasent *getaliasent(void);"
+.BI "int getaliasent_r(struct aliasent *restrict " result ,
+.BI "                     char " buffer "[restrict ." buflen "], \
+size_t " buflen ,
+.BI "                     struct aliasent **restrict " res );
+.P
+.BI "struct aliasent *getaliasbyname(const char *" name );
+.BI "int getaliasbyname_r(const char *restrict " name ,
+.BI "                     struct aliasent *restrict " result ,
+.BI "                     char " buffer "[restrict ." buflen "], \
+size_t " buflen ,
+.BI "                     struct aliasent **restrict " res );
+.fi
+.SH DESCRIPTION
+One of the databases available with the Name Service Switch (NSS)
+is the aliases database, that contains mail aliases.
+(To find out which databases are supported, try
+.IR "getent \-\-help" .)
+Six functions are provided to access the aliases database.
+.P
+The
+.BR getaliasent ()
+function returns a pointer to a structure containing
+the group information from the aliases database.
+The first time it is called it returns the first entry;
+thereafter, it returns successive entries.
+.P
+The
+.BR setaliasent ()
+function rewinds the file pointer to the beginning of the
+aliases database.
+.P
+The
+.BR endaliasent ()
+function closes the aliases database.
+.P
+.BR getaliasent_r ()
+is the reentrant version of the previous function.
+The requested structure
+is stored via the first argument but the programmer needs to fill the other
+arguments also.
+Not providing enough space causes the function to fail.
+.P
+The function
+.BR getaliasbyname ()
+takes the name argument and searches the aliases database.
+The entry is returned as a pointer to a
+.IR "struct aliasent" .
+.P
+.BR getaliasbyname_r ()
+is the reentrant version of the previous function.
+The requested structure
+is stored via the second argument but the programmer needs to fill the other
+arguments also.
+Not providing enough space causes the function to fail.
+.P
+The
+.I "struct aliasent"
+is defined in
+.IR <aliases.h> :
+.P
+.in +4n
+.EX
+struct aliasent {
+    char    *alias_name;             /* alias name */
+    size_t   alias_members_len;
+    char   **alias_members;          /* alias name list */
+    int      alias_local;
+};
+.EE
+.in
+.SH RETURN VALUE
+The functions
+.BR getaliasent_r ()
+and
+.BR getaliasbyname_r ()
+return a nonzero value on error.
+.SH FILES
+The default alias database is the file
+.IR /etc/aliases .
+This can be changed in the
+.I /etc/nsswitch.conf
+file.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setaliasent (),
+.BR endaliasent (),
+.BR getaliasent_r (),
+.BR getaliasbyname_r ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR getaliasent (),
+.BR getaliasbyname ()
+T}	Thread safety	MT-Unsafe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+The NeXT system has similar routines:
+.P
+.in +4n
+.EX
+#include <aliasdb.h>
+\&
+void alias_setent(void);
+void alias_endent(void);
+alias_ent *alias_getent(void);
+alias_ent *alias_getbyname(char *name);
+.EE
+.in
+.SH EXAMPLES
+The following example compiles with
+.IR "gcc example.c \-o example" .
+It will dump all names in the alias database.
+.P
+.\" SRC BEGIN (setaliasent.c)
+.EX
+#include <aliases.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(void)
+{
+    struct aliasent *al;
+\&
+    setaliasent();
+    for (;;) {
+        al = getaliasent();
+        if (al == NULL)
+            break;
+        printf("Name: %s\en", al\->alias_name);
+    }
+    if (errno) {
+        perror("reading alias");
+        exit(EXIT_FAILURE);
+    }
+    endaliasent();
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR getgrent (3),
+.BR getpwent (3),
+.BR getspent (3),
+.BR aliases (5)
+.\"
+.\" /etc/sendmail/aliases
+.\" Yellow Pages
+.\" newaliases, postalias
diff --git a/man/man3/setbuf.3 b/man/man3/setbuf.3
new file mode 100644
index 000000000..8604d4754
--- /dev/null
+++ b/man/man3/setbuf.3
@@ -0,0 +1,227 @@
+'\" t
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" the American National Standards Committee X3, on Information
+.\" Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)setbuf.3	6.10 (Berkeley) 6/29/91
+.\"
+.\" Converted for Linux, Mon Nov 29 14:55:24 1993, faith@cs.unc.edu
+.\" Added section to BUGS, Sun Mar 12 22:28:33 MET 1995,
+.\"                   Thomas.Koenig@ciw.uni-karlsruhe.de
+.\" Correction,  Sun, 11 Apr 1999 15:55:18,
+.\"     Martin Vicente <martin@netadmin.dgac.fr>
+.\" Correction,  2000-03-03, Andreas Jaeger <aj@suse.de>
+.\" Added return value for setvbuf, aeb,
+.\"
+.TH setbuf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setbuf, setbuffer, setlinebuf, setvbuf \- stream buffering operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int setvbuf(FILE *restrict " stream ", char " buf "[restrict ." size ],
+.BI "            int " mode ", size_t " size );
+.P
+.BI "void setbuf(FILE *restrict " stream ", char *restrict " buf );
+.BI "void setbuffer(FILE *restrict " stream ", char " buf "[restrict ." size ],
+.BI "            size_t "  size );
+.BI "void setlinebuf(FILE *" stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR setbuffer (),
+.BR setlinebuf ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The three types of buffering available are unbuffered, block buffered, and
+line buffered.
+When an output stream is unbuffered, information appears on
+the destination file or terminal as soon as written; when it is block
+buffered, many characters are saved up and written as a block; when it is
+line buffered, characters are saved up until a newline is output or input is
+read from any stream attached to a terminal device (typically \fIstdin\fP).
+The function
+.BR fflush (3)
+may be used to force the block out early.
+(See
+.BR fclose (3).)
+.P
+Normally all files are block buffered.
+If a stream refers to a terminal (as
+.I stdout
+normally does), it is line buffered.
+The standard error stream
+.I stderr
+is always unbuffered by default.
+.P
+The
+.BR setvbuf ()
+function may be used on any open stream to change its buffer.
+The
+.I mode
+argument must be one of the following three macros:
+.RS
+.TP
+.B _IONBF
+unbuffered
+.TP
+.B _IOLBF
+line buffered
+.TP
+.B _IOFBF
+fully buffered
+.RE
+.P
+Except for unbuffered files, the
+.I buf
+argument should point to a buffer at least
+.I size
+bytes long; this buffer will be used instead of the current buffer.
+If the argument
+.I buf
+is NULL,
+only the mode is affected; a new buffer will be allocated on the next read
+or write operation.
+The
+.BR setvbuf ()
+function may be used only after opening a stream and before any other
+operations have been performed on it.
+.P
+The other three calls are, in effect, simply aliases for calls to
+.BR setvbuf ().
+The
+.BR setbuf ()
+function is exactly equivalent to the call
+.P
+.in +4n
+setvbuf(stream, buf, buf ? _IOFBF : _IONBF, BUFSIZ);
+.in
+.P
+The
+.BR setbuffer ()
+function is the same, except that the size of the buffer is up to the
+caller, rather than being determined by the default
+.BR BUFSIZ .
+The
+.BR setlinebuf ()
+function is exactly equivalent to the call:
+.P
+.in +4n
+setvbuf(stream, NULL, _IOLBF, 0);
+.in
+.SH RETURN VALUE
+The function
+.BR setvbuf ()
+returns 0 on success.
+It returns nonzero on failure
+.RI ( mode
+is invalid or the request cannot be honored).
+It may set
+.I errno
+on failure.
+.P
+The other functions do not return a value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setbuf (),
+.BR setbuffer (),
+.BR setlinebuf (),
+.BR setvbuf ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR setbuf ()
+.TQ
+.BR setvbuf ()
+C11, POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR setbuf ()
+.TQ
+.BR setvbuf ()
+C89, POSIX.1-2001.
+.SH CAVEATS
+POSIX notes
+.\" https://www.austingroupbugs.net/view.php?id=397#c799
+.\" 0000397: setbuf and errno
+that the value of
+.I errno
+is unspecified after a call to
+.BR setbuf ()
+and further notes that, since the value of
+.I errno
+is not required to be unchanged after a successful call to
+.BR setbuf (),
+applications should instead use
+.BR setvbuf ()
+in order to detect errors.
+.SH BUGS
+.\" The
+.\" .BR setbuffer ()
+.\" and
+.\" .BR setlinebuf ()
+.\" functions are not portable to versions of BSD before 4.2BSD, and
+.\" are available under Linux since libc 4.5.21.
+.\" On 4.2BSD and 4.3BSD systems,
+.\" .BR setbuf ()
+.\" always uses a suboptimal buffer size and should be avoided.
+.\".P
+You must make sure that the space that
+.I buf
+points to still exists by the time
+.I stream
+is closed, which also happens at program termination.
+For example, the following is invalid:
+.P
+.\" SRC BEGIN (setbuf.c)
+.EX
+#include <stdio.h>
+\&
+int
+main(void)
+{
+    char buf[BUFSIZ];
+\&
+    setbuf(stdout, buf);
+    printf("Hello, world!\en");
+    return 0;
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR stdbuf (1),
+.BR fclose (3),
+.BR fflush (3),
+.BR fopen (3),
+.BR fread (3),
+.BR malloc (3),
+.BR printf (3),
+.BR puts (3)
diff --git a/man/man3/setbuffer.3 b/man/man3/setbuffer.3
new file mode 100644
index 000000000..dc02d9e88
--- /dev/null
+++ b/man/man3/setbuffer.3
@@ -0,0 +1 @@
+.so man3/setbuf.3
diff --git a/man/man3/setcontext.3 b/man/man3/setcontext.3
new file mode 100644
index 000000000..b01818d4f
--- /dev/null
+++ b/man/man3/setcontext.3
@@ -0,0 +1 @@
+.so man3/getcontext.3
diff --git a/man/man3/setenv.3 b/man/man3/setenv.3
new file mode 100644
index 000000000..59df11cc9
--- /dev/null
+++ b/man/man3/setenv.3
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (C) 2004, 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:20:58 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Fri Feb 14 21:47:50 1997 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified 9 Jun 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Changed unsetenv() prototype; added EINVAL error
+.\"     Noted nonstandard behavior of setenv() if name contains '='
+.\" 2005-08-12, mtk, glibc 2.3.4 fixed the "name contains '='" bug
+.\"
+.TH setenv 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setenv \- change or add an environment variable
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int setenv(const char *" name ", const char *" value ", int " overwrite );
+.BI "int unsetenv(const char *" name );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR setenv (),
+.BR unsetenv ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR setenv ()
+function adds the variable
+.I name
+to the
+environment with the value
+.IR value ,
+if
+.I name
+does not
+already exist.
+If
+.I name
+does exist in the environment, then
+its value is changed to
+.I value
+if
+.I overwrite
+is nonzero;
+if
+.I overwrite
+is zero, then the value of
+.I name
+is not changed (and
+.BR setenv ()
+returns a success status).
+This function makes copies of the strings pointed to by
+.I name
+and
+.I value
+(by contrast with
+.BR putenv (3)).
+.P
+The
+.BR unsetenv ()
+function deletes the variable
+.I name
+from
+the environment.
+If
+.I name
+does not exist in the environment,
+then the function succeeds, and the environment is unchanged.
+.SH RETURN VALUE
+.BR setenv ()
+and
+.BR unsetenv ()
+functions return zero on success,
+or \-1 on error, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I name
+is NULL, points to a string of length 0,
+or contains an \[aq]=\[aq] character.
+.TP
+.B ENOMEM
+Insufficient memory to add a new variable to the environment.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setenv (),
+.BR unsetenv ()
+T}	Thread safety	MT-Unsafe const:env
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.P
+Prior to glibc 2.2.2,
+.BR unsetenv ()
+was prototyped
+as returning
+.IR void ;
+more recent glibc versions follow the
+POSIX.1-compliant prototype shown in the SYNOPSIS.
+.SH CAVEATS
+POSIX.1 does not require
+.BR setenv ()
+or
+.BR unsetenv ()
+to be reentrant.
+.SH BUGS
+POSIX.1 specifies that if
+.I name
+contains an \[aq]=\[aq] character, then
+.BR setenv ()
+should fail with the error
+.BR EINVAL ;
+however, versions of glibc before glibc 2.3.4 allowed an \[aq]=\[aq] sign in
+.IR name .
+.SH SEE ALSO
+.BR clearenv (3),
+.BR getenv (3),
+.BR putenv (3),
+.BR environ (7)
diff --git a/man/man3/setfsent.3 b/man/man3/setfsent.3
new file mode 100644
index 000000000..1e6a3eb7e
--- /dev/null
+++ b/man/man3/setfsent.3
@@ -0,0 +1 @@
+.so man3/getfsent.3
diff --git a/man/man3/setgrent.3 b/man/man3/setgrent.3
new file mode 100644
index 000000000..bde736fff
--- /dev/null
+++ b/man/man3/setgrent.3
@@ -0,0 +1 @@
+.so man3/getgrent.3
diff --git a/man/man3/sethostent.3 b/man/man3/sethostent.3
new file mode 100644
index 000000000..7d0fb4b7c
--- /dev/null
+++ b/man/man3/sethostent.3
@@ -0,0 +1 @@
+.so man3/gethostbyname.3
diff --git a/man/man3/sethostid.3 b/man/man3/sethostid.3
new file mode 100644
index 000000000..3210db030
--- /dev/null
+++ b/man/man3/sethostid.3
@@ -0,0 +1 @@
+.so man3/gethostid.3
diff --git a/man/man3/setjmp.3 b/man/man3/setjmp.3
new file mode 100644
index 000000000..2319feb47
--- /dev/null
+++ b/man/man3/setjmp.3
@@ -0,0 +1,332 @@
+'\" t
+.\" Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH setjmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setjmp, sigsetjmp, longjmp, siglongjmp  \- performing a nonlocal goto
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <setjmp.h>
+.P
+.BI "int setjmp(jmp_buf " env );
+.BI "int sigsetjmp(sigjmp_buf " env ", int " savesigs );
+.P
+.BI "[[noreturn]] void longjmp(jmp_buf " env ", int " val );
+.BI "[[noreturn]] void siglongjmp(sigjmp_buf " env ", int " val );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR setjmp ():
+see NOTES.
+.P
+.BR sigsetjmp ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+The functions described on this page are used for performing "nonlocal gotos":
+transferring execution from one function to a predetermined location
+in another function.
+The
+.BR setjmp ()
+function dynamically establishes the target to which control
+will later be transferred, and
+.BR longjmp ()
+performs the transfer of execution.
+.P
+The
+.BR setjmp ()
+function saves various information about the calling environment
+(typically, the stack pointer, the instruction pointer,
+possibly the values of other registers and the signal mask)
+in the buffer
+.I env
+for later use by
+.BR longjmp ().
+In this case,
+.BR setjmp ()
+returns 0.
+.P
+The
+.BR longjmp ()
+function uses the information saved in
+.I env
+to transfer control back to the point where
+.BR setjmp ()
+was called and to restore ("rewind") the stack to its state at the time of the
+.BR setjmp ()
+call.
+In addition, and depending on the implementation (see NOTES),
+the values of some other registers and the process signal mask
+may be restored to their state at the time of the
+.BR setjmp ()
+call.
+.P
+Following a successful
+.BR longjmp (),
+execution continues as if
+.BR setjmp ()
+had returned for a second time.
+This "fake" return can be distinguished from a true
+.BR setjmp ()
+call because the "fake" return returns the value provided in
+.IR val .
+If the programmer mistakenly passes the value 0 in
+.IR val ,
+the "fake" return will instead return 1.
+.SS sigsetjmp() and siglongjmp()
+.BR sigsetjmp ()
+and
+.BR siglongjmp ()
+also perform nonlocal gotos, but provide predictable handling of
+the process signal mask.
+.P
+If, and only if, the
+.I savesigs
+argument provided to
+.BR sigsetjmp ()
+is nonzero, the process's current signal mask is saved in
+.I env
+and will be restored if a
+.BR siglongjmp ()
+is later performed with this
+.IR env .
+.SH RETURN VALUE
+.BR setjmp ()
+and
+.BR sigsetjmp ()
+return 0 when called directly;
+on the "fake" return that occurs after
+.BR longjmp ()
+or
+.BR siglongjmp (),
+the nonzero value specified in
+.I val
+is returned.
+.P
+The
+.BR longjmp ()
+or
+.BR siglongjmp ()
+functions do not return.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setjmp (),
+.BR sigsetjmp ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR longjmp (),
+.BR siglongjmp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR setjmp ()
+.TQ
+.BR longjmp ()
+C11, POSIX.1-2008.
+.TP
+.BR sigsetjmp ()
+.TQ
+.BR siglongjmp ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR setjmp ()
+.TQ
+.BR longjmp ()
+POSIX.1-2001, C89.
+.TP
+.BR sigsetjmp ()
+.TQ
+.BR siglongjmp ()
+POSIX.1-2001.
+.P
+POSIX does not specify whether
+.BR setjmp ()
+will save the signal mask
+(to be later restored during
+.BR longjmp ()).
+In System V it will not.
+In 4.3BSD it will, and there
+is a function
+.BR _setjmp ()
+that will not.
+The behavior under Linux depends on the glibc version
+and the setting of feature test macros.
+Before glibc 2.19,
+.BR setjmp ()
+follows the System V behavior by default,
+but the BSD behavior is provided if the
+.B _BSD_SOURCE
+feature test macro is explicitly defined
+.\" so that _FAVOR_BSD is triggered
+and none of
+.BR _POSIX_SOURCE ,
+.BR _POSIX_C_SOURCE ,
+.BR _XOPEN_SOURCE ,
+.\" .BR _XOPEN_SOURCE_EXTENDED ,
+.BR _GNU_SOURCE ,
+or
+.B _SVID_SOURCE
+is defined.
+Since glibc 2.19,
+.I <setjmp.h>
+exposes only the System V version of
+.BR setjmp ().
+Programs that need the BSD semantics should replace calls to
+.BR setjmp ()
+with calls to
+.BR sigsetjmp ()
+with a nonzero
+.I savesigs
+argument.
+.SH NOTES
+.BR setjmp ()
+and
+.BR longjmp ()
+can be useful for dealing with errors inside deeply nested function calls
+or to allow a signal handler to pass control to
+a specific point in the program,
+rather than returning to the point where the handler interrupted
+the main program.
+In the latter case,
+if you want to portably save and restore signal masks, use
+.BR sigsetjmp ()
+and
+.BR siglongjmp ().
+See also the discussion of program readability below.
+.SH CAVEATS
+The compiler may optimize variables into registers, and
+.BR longjmp ()
+may restore the values of other registers in addition to the
+stack pointer and program counter.
+Consequently, the values of automatic variables are unspecified
+after a call to
+.BR longjmp ()
+if they meet all the following criteria:
+.IP \[bu] 3
+they are local to the function that made the corresponding
+.BR setjmp ()
+call;
+.IP \[bu]
+their values are changed between the calls to
+.BR setjmp ()
+and
+.BR longjmp ();
+and
+.IP \[bu]
+they are not declared as
+.IR volatile .
+.P
+Analogous remarks apply for
+.BR siglongjmp ().
+.\"
+.SS Nonlocal gotos and program readability
+While it can be abused,
+the traditional C "goto" statement at least has the benefit that lexical cues
+(the goto statement and the target label)
+allow the programmer to easily perceive the flow of control.
+Nonlocal gotos provide no such cues: multiple
+.BR setjmp ()
+calls might employ the same
+.I jmp_buf
+variable so that the content of the variable may change
+over the lifetime of the application.
+Consequently, the programmer may be forced to perform detailed
+reading of the code to determine the dynamic target of a particular
+.BR longjmp ()
+call.
+(To make the programmer's life easier, each
+.BR setjmp ()
+call should employ a unique
+.I jmp_buf
+variable.)
+.P
+Adding further difficulty, the
+.BR setjmp ()
+and
+.BR longjmp ()
+calls may not even be in the same source code module.
+.P
+In summary, nonlocal gotos can make programs harder to understand
+and maintain, and an alternative should be used if possible.
+.\"
+.SS Undefined Behavior
+If the function which called
+.BR setjmp ()
+returns before
+.BR longjmp ()
+is called, the behavior is undefined.
+Some kind of subtle or unsubtle chaos is sure to result.
+.P
+If, in a multithreaded program, a
+.BR longjmp ()
+call employs an
+.I env
+buffer that was initialized by a call to
+.BR setjmp ()
+in a different thread, the behavior is undefined.
+.\"
+.\" The following statement appeared in versions up to POSIX.1-2008 TC1,
+.\" but is set to be removed in POSIX.1-2008 TC2:
+.\"
+.\"     According to POSIX.1, if a
+.\"     .BR longjmp ()
+.\"     call is performed from a nested signal handler
+.\"     (i.e., from a handler that was invoked in response to a signal that was
+.\"     generated while another signal was already in the process of being
+.\"     handled), the behavior is undefined.
+.P
+POSIX.1-2008 Technical Corrigendum 2 adds
+.\" http://austingroupbugs.net/view.php?id=516#c1195
+.BR longjmp ()
+and
+.BR siglongjmp ()
+to the list of async-signal-safe functions.
+However, the standard recommends avoiding the use of these functions
+from signal handlers and goes on to point out that
+if these functions are called from a signal handler that interrupted
+a call to a non-async-signal-safe function (or some equivalent,
+such as the steps equivalent to
+.BR exit (3)
+that occur upon a return from the initial call to
+.IR main ()),
+the behavior is undefined if the program subsequently makes a call to
+a non-async-signal-safe function.
+The only way of avoiding undefined behavior is to ensure one of the following:
+.IP \[bu] 3
+After long jumping from the signal handler,
+the program does not call any non-async-signal-safe functions
+and does not return from the initial call to
+.IR main ().
+.IP \[bu]
+Any signal whose handler performs a long jump must be blocked during
+.I every
+call to a non-async-signal-safe function and
+no non-async-signal-safe functions are called after
+returning from the initial call to
+.IR main ().
+.SH SEE ALSO
+.BR signal (7),
+.BR signal\-safety (7)
diff --git a/man/man3/setkey.3 b/man/man3/setkey.3
new file mode 100644
index 000000000..e34c9e911
--- /dev/null
+++ b/man/man3/setkey.3
@@ -0,0 +1 @@
+.so man3/encrypt.3
diff --git a/man/man3/setkey_r.3 b/man/man3/setkey_r.3
new file mode 100644
index 000000000..e34c9e911
--- /dev/null
+++ b/man/man3/setkey_r.3
@@ -0,0 +1 @@
+.so man3/encrypt.3
diff --git a/man/man3/setlinebuf.3 b/man/man3/setlinebuf.3
new file mode 100644
index 000000000..dc02d9e88
--- /dev/null
+++ b/man/man3/setlinebuf.3
@@ -0,0 +1 @@
+.so man3/setbuf.3
diff --git a/man/man3/setlocale.3 b/man/man3/setlocale.3
new file mode 100644
index 000000000..3ec86d5a5
--- /dev/null
+++ b/man/man3/setlocale.3
@@ -0,0 +1,248 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright 1999 by Bruno Haible (haible@clisp.cons.org)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 18:20:12 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Tue Jul 15 16:49:10 1997 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Sun Jul  4 14:52:16 1999 by Bruno Haible (haible@clisp.cons.org)
+.\" Modified Tue Aug 24 17:11:01 1999 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Tue Feb  6 03:31:55 2001 by Andries Brouwer (aeb@cwi.nl)
+.\"
+.TH setlocale 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setlocale \- set the current locale
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <locale.h>
+.P
+.BI "char *setlocale(int " category ", const char *" locale );
+.fi
+.SH DESCRIPTION
+The
+.BR setlocale ()
+function is used to set or query the program's current locale.
+.P
+If
+.I locale
+is not NULL,
+the program's current locale is modified according to the arguments.
+The argument
+.I category
+determines which parts of the program's current locale should be modified.
+.TS
+lB lB
+lB lx.
+Category	Governs
+LC_ALL	All of the locale
+LC_ADDRESS	T{
+Formatting of addresses and
+geography-related items (*)
+T}
+LC_COLLATE	String collation
+LC_CTYPE	Character classification
+LC_IDENTIFICATION	T{
+Metadata describing the locale (*)
+T}
+LC_MEASUREMENT	T{
+Settings related to measurements
+(metric versus US customary) (*)
+T}
+LC_MESSAGES	T{
+Localizable natural-language messages
+T}
+LC_MONETARY	T{
+Formatting of monetary values
+T}
+LC_NAME	T{
+Formatting of salutations for persons (*)
+T}
+LC_NUMERIC	T{
+Formatting of nonmonetary numeric values
+T}
+LC_PAPER	T{
+Settings related to the standard paper size (*)
+T}
+LC_TELEPHONE	T{
+Formats to be used with telephone services (*)
+T}
+LC_TIME	T{
+Formatting of date and time values
+T}
+.TE
+.P
+The categories marked with an asterisk in the above table
+are GNU extensions.
+For further information on these locale categories, see
+.BR locale (7).
+.P
+The argument
+.I locale
+is a pointer to a character string containing the
+required setting of
+.IR category .
+Such a string is either a well-known constant like "C" or "da_DK"
+(see below), or an opaque string that was returned by another call of
+.BR setlocale ().
+.P
+If
+.I locale
+is an empty string,
+.BR \[dq]\[dq] ,
+each part of the locale that should be modified is set according to the
+environment variables.
+The details are implementation-dependent.
+For glibc, first (regardless of
+.IR category ),
+the environment variable
+.B LC_ALL
+is inspected,
+next the environment variable with the same name as the category
+(see the table above),
+and finally the environment variable
+.BR LANG .
+The first existing environment variable is used.
+If its value is not a valid locale specification, the locale
+is unchanged, and
+.BR setlocale ()
+returns NULL.
+.P
+The locale
+.B \[dq]C\[dq]
+or
+.B \[dq]POSIX\[dq]
+is a portable locale;
+it exists on all conforming systems.
+.P
+A locale name is typically of the form
+.IR language "[_" territory "][." codeset "][@" modifier "],"
+where
+.I language
+is an ISO\~639 language code,
+.I territory
+is an ISO\~3166 country code, and
+.I codeset
+is a character set or encoding identifier like
+.B "ISO\-8859\-1"
+or
+.BR "UTF\-8" .
+For a list of all supported locales, try "locale \-a" (see
+.BR locale (1)).
+.P
+If
+.I locale
+is NULL, the current locale is only queried, not modified.
+.P
+On startup of the main program, the portable
+.B \[dq]C\[dq]
+locale is selected as default.
+A program may be made portable to all locales by calling:
+.P
+.in +4n
+.EX
+setlocale(LC_ALL, "");
+.EE
+.in
+.P
+after program initialization, and then:
+.IP \[bu] 3
+using the values returned from a
+.BR localeconv (3)
+call for locale-dependent information;
+.IP \[bu]
+using the multibyte and wide character functions for text processing if
+.BR "MB_CUR_MAX > 1" ;
+.IP \[bu]
+using
+.BR strcoll (3)
+and
+.BR strxfrm (3)
+to compare strings; and
+.IP \[bu]
+using
+.BR wcscoll (3)
+and
+.BR wcsxfrm (3)
+to compare wide-character strings.
+.SH RETURN VALUE
+A successful call to
+.BR setlocale ()
+returns an opaque string that corresponds to the locale set.
+This string may be allocated in static storage.
+The string returned is such that a subsequent call with that string
+and its associated category will restore that part of the process's
+locale.
+The return value is NULL if the request cannot be honored.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setlocale ()
+T}	Thread safety	MT-Unsafe const:locale env
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SS Categories
+.TP
+.B LC_ALL
+.TQ
+.B LC_COLLATE
+.TQ
+.B LC_CTYPE
+.TQ
+.B LC_MONETARY
+.TQ
+.B LC_NUMERIC
+.TQ
+.B LC_TIME
+C11, POSIX.1-2008.
+.TP
+.B LC_MESSAGES
+POSIX.1-2008.
+.TP
+Others:
+GNU.
+.SH HISTORY
+POSIX.1-2001, C89.
+.SS Categories
+.TP
+.B LC_ALL
+.TQ
+.B LC_COLLATE
+.TQ
+.B LC_CTYPE
+.TQ
+.B LC_MONETARY
+.TQ
+.B LC_NUMERIC
+.TQ
+.B LC_TIME
+C89, POSIX.1-2001.
+.TP
+.B LC_MESSAGES
+POSIX.1-2001.
+.TP
+Others:
+GNU.
+.SH SEE ALSO
+.BR locale (1),
+.BR localedef (1),
+.BR isalpha (3),
+.BR localeconv (3),
+.BR nl_langinfo (3),
+.BR rpmatch (3),
+.BR strcoll (3),
+.BR strftime (3),
+.BR charsets (7),
+.BR locale (7)
diff --git a/man/man3/setlogmask.3 b/man/man3/setlogmask.3
new file mode 100644
index 000000000..12347fd36
--- /dev/null
+++ b/man/man3/setlogmask.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH setlogmask 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setlogmask \- set log priority mask
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <syslog.h>
+.P
+.BI "int setlogmask(int " mask );
+.fi
+.SH DESCRIPTION
+A process has a log priority mask that determines which calls to
+.BR syslog (3)
+may be logged.
+All other calls will be ignored.
+Logging is enabled for the priorities that have the corresponding
+bit set in
+.IR mask .
+The initial mask is such that logging is enabled for all priorities.
+.P
+The
+.BR setlogmask ()
+function sets this logmask for the calling process,
+and returns the previous mask.
+If the
+.I mask
+argument is
+.BR 0 ,
+the current logmask is not modified.
+.P
+The eight priorities are
+.BR LOG_EMERG ,
+.BR LOG_ALERT ,
+.BR LOG_CRIT ,
+.BR LOG_ERR ,
+.BR LOG_WARNING ,
+.BR LOG_NOTICE ,
+.BR LOG_INFO ,
+and
+.BR LOG_DEBUG .
+The bit corresponding to a priority
+.I p
+is
+.IR LOG_MASK(p) .
+Some systems also provide a macro
+.I LOG_UPTO(p)
+for the mask
+of all priorities in the above list up to and including
+.IR p .
+.SH RETURN VALUE
+This function returns the previous log priority mask.
+.SH ERRORS
+None.
+.\" .SH NOTES
+.\" The glibc logmask handling was broken before glibc 2.1.1.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setlogmask ()
+T}	Thread safety	MT-Unsafe race:LogMask
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.\" Note that the description in POSIX.1-2001 is flawed.
+.P
+.BR LOG_UPTO ()
+will be included in the next release of the POSIX specification (Issue 8).
+.\" FIXME . https://www.austingroupbugs.net/view.php?id=1033
+.SH SEE ALSO
+.BR closelog (3),
+.BR openlog (3),
+.BR syslog (3)
diff --git a/man/man3/setmntent.3 b/man/man3/setmntent.3
new file mode 100644
index 000000000..3c2bb35c9
--- /dev/null
+++ b/man/man3/setmntent.3
@@ -0,0 +1 @@
+.so man3/getmntent.3
diff --git a/man/man3/setnetent.3 b/man/man3/setnetent.3
new file mode 100644
index 000000000..70f5670dc
--- /dev/null
+++ b/man/man3/setnetent.3
@@ -0,0 +1 @@
+.so man3/getnetent.3
diff --git a/man/man3/setnetgrent.3 b/man/man3/setnetgrent.3
new file mode 100644
index 000000000..86eee0cb9
--- /dev/null
+++ b/man/man3/setnetgrent.3
@@ -0,0 +1,170 @@
+'\" t
+.\"  Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\"  based on glibc infopages
+.\" polished - aeb
+.\"
+.TH setnetgrent 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+setnetgrent, endnetgrent, getnetgrent, getnetgrent_r, innetgr \-
+handle network group entries
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <netdb.h>
+.P
+.BI "int setnetgrent(const char *" netgroup );
+.B "void endnetgrent(void);"
+.P
+.BI "int getnetgrent(char **restrict " host ,
+.BI "            char **restrict " user ", char **restrict " domain );
+.BI "int getnetgrent_r(char **restrict " host ,
+.BI "            char **restrict " user ", char **restrict " domain ,
+.BI "            char " buf "[restrict ." buflen "], size_t " buflen );
+.P
+.BI "int innetgr(const char *" netgroup ", const char *" host ,
+.BI "            const char *" user ", const char *" domain );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR \%setnetgrent (),
+.BR \%endnetgrent (),
+.BR \%getnetgrent (),
+.BR \%getnetgrent_r (),
+.BR \%innetgr ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.I netgroup
+is a SunOS invention.
+A netgroup database is a list of string triples
+.RI ( hostname ", " username ", " domainname )
+or other netgroup names.
+Any of the elements in a triple can be empty,
+which means that anything matches.
+The functions described here allow access to the netgroup databases.
+The file
+.I /etc/nsswitch.conf
+defines what database is searched.
+.P
+The
+.BR setnetgrent ()
+call defines the netgroup that will be searched by subsequent
+.BR getnetgrent ()
+calls.
+The
+.BR getnetgrent ()
+function retrieves the next netgroup entry, and returns pointers in
+.IR host ,
+.IR user ,
+.IR domain .
+A null pointer means that the corresponding entry matches any string.
+The pointers are valid only as long as there is no call to other
+netgroup-related functions.
+To avoid this problem you can use the GNU function
+.BR getnetgrent_r ()
+that stores the strings in the supplied buffer.
+To free all allocated buffers use
+.BR endnetgrent ().
+.P
+In most cases you want to check only if the triplet
+.RI ( hostname ", " username ", " domainname )
+is a member of a netgroup.
+The function
+.BR innetgr ()
+can be used for this without calling the above three functions.
+Again, a null pointer is a wildcard and matches any string.
+The function is thread-safe.
+.SH RETURN VALUE
+These functions return 1 on success and 0 for failure.
+.SH FILES
+.I /etc/netgroup
+.br
+.I /etc/nsswitch.conf
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR setnetgrent (),
+.BR getnetgrent_r (),
+.BR innetgr ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:netgrent
+locale
+T}
+T{
+.na
+.nh
+.BR endnetgrent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:netgrent
+T}
+T{
+.na
+.nh
+.BR getnetgrent ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:netgrent
+race:netgrentbuf locale
+T}
+.TE
+.P
+In the above table,
+.I netgrent
+in
+.I race:netgrent
+signifies that if any of the functions
+.BR setnetgrent (),
+.BR getnetgrent_r (),
+.BR innetgr (),
+.BR getnetgrent (),
+or
+.BR endnetgrent ()
+are used in parallel in different threads of a program,
+then data races could occur.
+.SH VERSIONS
+In the BSD implementation,
+.BR setnetgrent ()
+returns void.
+.SH STANDARDS
+None.
+.SH HISTORY
+.BR setnetgrent (),
+.BR endnetgrent (),
+.BR getnetgrent (),
+and
+.BR innetgr ()
+are available on most UNIX systems.
+.BR getnetgrent_r ()
+is not widely available on other systems.
+.\" getnetgrent_r() is on Solaris 8 and AIX 5.1, but not the BSDs.
+.SH SEE ALSO
+.BR sethostent (3),
+.BR setprotoent (3),
+.BR setservent (3)
diff --git a/man/man3/setprotoent.3 b/man/man3/setprotoent.3
new file mode 100644
index 000000000..f8cb4bba2
--- /dev/null
+++ b/man/man3/setprotoent.3
@@ -0,0 +1 @@
+.so man3/getprotoent.3
diff --git a/man/man3/setpwent.3 b/man/man3/setpwent.3
new file mode 100644
index 000000000..f2d121b80
--- /dev/null
+++ b/man/man3/setpwent.3
@@ -0,0 +1 @@
+.so man3/getpwent.3
diff --git a/man/man3/setrpcent.3 b/man/man3/setrpcent.3
new file mode 100644
index 000000000..923085e2e
--- /dev/null
+++ b/man/man3/setrpcent.3
@@ -0,0 +1 @@
+.so man3/getrpcent.3
diff --git a/man/man3/setservent.3 b/man/man3/setservent.3
new file mode 100644
index 000000000..eaafb1c1e
--- /dev/null
+++ b/man/man3/setservent.3
@@ -0,0 +1 @@
+.so man3/getservent.3
diff --git a/man/man3/setspent.3 b/man/man3/setspent.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/setspent.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/setstate.3 b/man/man3/setstate.3
new file mode 100644
index 000000000..6e34104e2
--- /dev/null
+++ b/man/man3/setstate.3
@@ -0,0 +1 @@
+.so man3/random.3
diff --git a/man/man3/setstate_r.3 b/man/man3/setstate_r.3
new file mode 100644
index 000000000..b01937f4d
--- /dev/null
+++ b/man/man3/setstate_r.3
@@ -0,0 +1 @@
+.so man3/random_r.3
diff --git a/man/man3/setttyent.3 b/man/man3/setttyent.3
new file mode 100644
index 000000000..1cd11e3d8
--- /dev/null
+++ b/man/man3/setttyent.3
@@ -0,0 +1 @@
+.so man3/getttyent.3
diff --git a/man/man3/setusershell.3 b/man/man3/setusershell.3
new file mode 100644
index 000000000..718ed12e9
--- /dev/null
+++ b/man/man3/setusershell.3
@@ -0,0 +1 @@
+.so man3/getusershell.3
diff --git a/man/man3/setutent.3 b/man/man3/setutent.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/setutent.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/setutxent.3 b/man/man3/setutxent.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/setutxent.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/setvbuf.3 b/man/man3/setvbuf.3
new file mode 100644
index 000000000..dc02d9e88
--- /dev/null
+++ b/man/man3/setvbuf.3
@@ -0,0 +1 @@
+.so man3/setbuf.3
diff --git a/man/man3/sgetspent.3 b/man/man3/sgetspent.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/sgetspent.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/sgetspent_r.3 b/man/man3/sgetspent_r.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/sgetspent_r.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/shm_open.3 b/man/man3/shm_open.3
new file mode 100644
index 000000000..a907df906
--- /dev/null
+++ b/man/man3/shm_open.3
@@ -0,0 +1,521 @@
+'\" t
+.\" Copyright (C) 2002, 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH shm_open 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+shm_open, shm_unlink \- create/open or unlink POSIX shared memory objects
+.SH LIBRARY
+Real-time library
+.RI ( librt ", " \-lrt )
+.SH SYNOPSIS
+.nf
+.B #include <sys/mman.h>
+.BR "#include <sys/stat.h>" "        /* For mode constants */"
+.BR "#include <fcntl.h>" "           /* For O_* constants */"
+.P
+.BI "int shm_open(const char *" name ", int " oflag ", mode_t " mode );
+.BI "int shm_unlink(const char *" name );
+.fi
+.SH DESCRIPTION
+.BR shm_open ()
+creates and opens a new, or opens an existing, POSIX shared memory object.
+A POSIX shared memory object is in effect a handle which can
+be used by unrelated processes to
+.BR mmap (2)
+the same region of shared memory.
+The
+.BR shm_unlink ()
+function performs the converse operation,
+removing an object previously created by
+.BR shm_open ().
+.P
+The operation of
+.BR shm_open ()
+is analogous to that of
+.BR open (2).
+.I name
+specifies the shared memory object to be created or opened.
+For portable use,
+a shared memory object should be identified by a name of the form
+.IR /somename ;
+that is, a null-terminated string of up to
+.B NAME_MAX
+(i.e., 255) characters consisting of an initial slash,
+.\" glibc allows the initial slash to be omitted, and makes
+.\" multiple initial slashes equivalent to a single slash.
+.\" This differs from the implementation of POSIX message queues.
+followed by one or more characters, none of which are slashes.
+.\" glibc allows subdirectory components in the name, in which
+.\" case the subdirectory must exist under /dev/shm, and allow the
+.\" required permissions if a user wants to create a shared memory
+.\" object in that subdirectory.
+.P
+.I oflag
+is a bit mask created by ORing together exactly one of
+.B O_RDONLY
+or
+.B O_RDWR
+and any of the other flags listed here:
+.TP
+.B O_RDONLY
+Open the object for read access.
+A shared memory object opened in this way can be
+.BR mmap (2)ed
+only for read
+.RB ( PROT_READ )
+access.
+.TP
+.B O_RDWR
+Open the object for read-write access.
+.TP
+.B O_CREAT
+Create the shared memory object if it does not exist.
+The user and group ownership of the object are taken
+from the corresponding effective IDs of the calling process,
+.\" In truth it is actually the filesystem IDs on Linux, but these
+.\" are nearly always the same as the effective IDs.  (MTK, Jul 05)
+and the object's
+permission bits are set according to the low-order 9 bits of
+.IR mode ,
+except that those bits set in the process file mode
+creation mask (see
+.BR umask (2))
+are cleared for the new object.
+A set of macro constants which can be used to define
+.I mode
+is listed in
+.BR open (2).
+(Symbolic definitions of these constants can be obtained by including
+.IR <sys/stat.h> .)
+.IP
+A new shared memory object initially has zero length\[em]the size of the
+object can be set using
+.BR ftruncate (2).
+The newly allocated bytes of a shared memory
+object are automatically initialized to 0.
+.TP
+.B O_EXCL
+If
+.B O_CREAT
+was also specified, and a shared memory object with the given
+.I name
+already exists, return an error.
+The check for the existence of the object, and its creation if it
+does not exist, are performed atomically.
+.TP
+.B O_TRUNC
+If the shared memory object already exists, truncate it to zero bytes.
+.P
+Definitions of these flag values can be obtained by including
+.IR <fcntl.h> .
+.P
+On successful completion
+.BR shm_open ()
+returns a new file descriptor referring to the shared memory object.
+This file descriptor is guaranteed to be the lowest-numbered file descriptor
+not previously opened within the process.
+The
+.B FD_CLOEXEC
+flag (see
+.BR fcntl (2))
+is set for the file descriptor.
+.P
+The file descriptor is normally used in subsequent calls
+to
+.BR ftruncate (2)
+(for a newly created object) and
+.BR mmap (2).
+After a call to
+.BR mmap (2)
+the file descriptor may be closed without affecting the memory mapping.
+.P
+The operation
+of
+.BR shm_unlink ()
+is analogous to
+.BR unlink (2):
+it removes a shared memory object name, and, once all processes
+have unmapped the object, deallocates and
+destroys the contents of the associated memory region.
+After a successful
+.BR shm_unlink (),
+attempts to
+.BR shm_open ()
+an object with the same
+.I name
+fail (unless
+.B O_CREAT
+was specified, in which case a new, distinct object is created).
+.SH RETURN VALUE
+On success,
+.BR shm_open ()
+returns a file descriptor (a nonnegative integer).
+On success,
+.BR shm_unlink ()
+returns 0.
+On failure, both functions return \-1 and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Permission to
+.BR shm_unlink ()
+the shared memory object was denied.
+.TP
+.B EACCES
+Permission was denied to
+.BR shm_open ()
+.I name
+in the specified
+.IR mode ,
+or
+.B O_TRUNC
+was specified and the caller does not have write permission on the object.
+.TP
+.B EEXIST
+Both
+.B O_CREAT
+and
+.B O_EXCL
+were specified to
+.BR shm_open ()
+and the shared memory object specified by
+.I name
+already exists.
+.TP
+.B EINVAL
+The
+.I name
+argument to
+.BR shm_open ()
+was invalid.
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENAMETOOLONG
+The length of
+.I name
+exceeds
+.BR PATH_MAX .
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+An attempt was made to
+.BR shm_open ()
+a
+.I name
+that did not exist, and
+.B O_CREAT
+was not specified.
+.TP
+.B ENOENT
+An attempt was to made to
+.BR shm_unlink ()
+a
+.I name
+that does not exist.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR shm_open (),
+.BR shm_unlink ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+POSIX leaves the behavior of the combination of
+.B O_RDONLY
+and
+.B O_TRUNC
+unspecified.
+On Linux, this will successfully truncate an existing
+shared memory object\[em]this may not be so on other UNIX systems.
+.P
+The POSIX shared memory object implementation on Linux makes use
+of a dedicated
+.BR tmpfs (5)
+filesystem that is normally mounted under
+.IR /dev/shm .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.
+POSIX.1-2001.
+.P
+POSIX.1-2001 says that the group ownership of a newly created shared
+memory object is set to either the calling process's effective group ID
+or "a system default group ID".
+POSIX.1-2008 says that the group ownership
+may be set to either the calling process's effective group ID
+or, if the object is visible in the filesystem,
+the group ID of the parent directory.
+.SH EXAMPLES
+The programs below employ POSIX shared memory and POSIX unnamed semaphores
+to exchange a piece of data.
+The "bounce" program (which must be run first) raises the case
+of a string that is placed into the shared memory by the "send" program.
+Once the data has been modified, the "send" program then prints
+the contents of the modified shared memory.
+An example execution of the two programs is the following:
+.P
+.in +4n
+.EX
+$ \fB./pshm_ucase_bounce /myshm &\fP
+[1] 270171
+$ \fB./pshm_ucase_send /myshm hello\fP
+HELLO
+.EE
+.in
+.P
+Further detail about these programs is provided below.
+.\"
+.SS Program source: pshm_ucase.h
+The following header file is included by both programs below.
+Its primary purpose is to define a structure that will be imposed
+on the memory object that is shared between the two programs.
+.P
+.in +4n
+.\" SRC BEGIN (pshm_ucase.h)
+.EX
+#ifndef PSHM_UCASE_H
+#define PSHM_UCASE_H
+\&
+#include <semaphore.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+#define BUF_SIZE 1024   /* Maximum size for exchanged string */
+\&
+/* Define a structure that will be imposed on the shared
+   memory object */
+\&
+struct shmbuf {
+    sem_t  sem1;            /* POSIX unnamed semaphore */
+    sem_t  sem2;            /* POSIX unnamed semaphore */
+    size_t cnt;             /* Number of bytes used in \[aq]buf\[aq] */
+    char   buf[BUF_SIZE];   /* Data being transferred */
+};
+\&
+#endif  // include guard
+.EE
+.\" SRC END
+.in
+.\"
+.SS Program source: pshm_ucase_bounce.c
+The "bounce" program creates a new shared memory object with the name
+given in its command-line argument and sizes the object to
+match the size of the
+.I shmbuf
+structure defined in the header file.
+It then maps the object into the process's address space,
+and initializes two POSIX semaphores inside the object to 0.
+.P
+After the "send" program has posted the first of the semaphores,
+the "bounce" program upper cases the data that has been placed
+in the memory by the "send" program and then posts the second semaphore
+to tell the "send" program that it may now access the shared memory.
+.P
+.in +4n
+.\" SRC BEGIN (pshm_ucase_bounce.c)
+.EX
+/* pshm_ucase_bounce.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#include <ctype.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+\&
+#include "pshm_ucase.h"
+\&
+int
+main(int argc, char *argv[])
+{
+    int            fd;
+    char           *shmpath;
+    struct shmbuf  *shmp;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s /shm\-path\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    shmpath = argv[1];
+\&
+    /* Create shared memory object and set its size to the size
+       of our structure. */
+\&
+    fd = shm_open(shmpath, O_CREAT | O_EXCL | O_RDWR, 0600);
+    if (fd == \-1)
+        errExit("shm_open");
+\&
+    if (ftruncate(fd, sizeof(struct shmbuf)) == \-1)
+        errExit("ftruncate");
+\&
+    /* Map the object into the caller\[aq]s address space. */
+\&
+    shmp = mmap(NULL, sizeof(*shmp), PROT_READ | PROT_WRITE,
+                MAP_SHARED, fd, 0);
+    if (shmp == MAP_FAILED)
+        errExit("mmap");
+\&
+    /* Initialize semaphores as process\-shared, with value 0. */
+\&
+    if (sem_init(&shmp\->sem1, 1, 0) == \-1)
+        errExit("sem_init\-sem1");
+    if (sem_init(&shmp\->sem2, 1, 0) == \-1)
+        errExit("sem_init\-sem2");
+\&
+    /* Wait for \[aq]sem1\[aq] to be posted by peer before touching
+       shared memory. */
+\&
+    if (sem_wait(&shmp\->sem1) == \-1)
+        errExit("sem_wait");
+\&
+    /* Convert data in shared memory into upper case. */
+\&
+    for (size_t j = 0; j < shmp\->cnt; j++)
+        shmp\->buf[j] = toupper((unsigned char) shmp\->buf[j]);
+\&
+    /* Post \[aq]sem2\[aq] to tell the peer that it can now
+       access the modified data in shared memory. */
+\&
+    if (sem_post(&shmp\->sem2) == \-1)
+        errExit("sem_post");
+\&
+    /* Unlink the shared memory object. Even if the peer process
+       is still using the object, this is okay. The object will
+       be removed only after all open references are closed. */
+\&
+    shm_unlink(shmpath);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.\"
+.SS Program source: pshm_ucase_send.c
+The "send" program takes two command-line arguments:
+the pathname of a shared memory object previously created by the "bounce"
+program and a string that is to be copied into that object.
+.P
+The program opens the shared memory object
+and maps the object into its address space.
+It then copies the data specified in its second argument
+into the shared memory,
+and posts the first semaphore,
+which tells the "bounce" program that it can now access that data.
+After the "bounce" program posts the second semaphore,
+the "send" program prints the contents of the shared memory
+on standard output.
+.P
+.in +4n
+.\" SRC BEGIN (pshm_ucase_send.c)
+.EX
+/* pshm_ucase_send.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+\&
+#include "pshm_ucase.h"
+\&
+int
+main(int argc, char *argv[])
+{
+    int            fd;
+    char           *shmpath, *string;
+    size_t         len;
+    struct shmbuf  *shmp;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s /shm\-path string\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    shmpath = argv[1];
+    string = argv[2];
+    len = strlen(string);
+\&
+    if (len > BUF_SIZE) {
+        fprintf(stderr, "String is too long\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Open the existing shared memory object and map it
+       into the caller\[aq]s address space. */
+\&
+    fd = shm_open(shmpath, O_RDWR, 0);
+    if (fd == \-1)
+        errExit("shm_open");
+\&
+    shmp = mmap(NULL, sizeof(*shmp), PROT_READ | PROT_WRITE,
+                MAP_SHARED, fd, 0);
+    if (shmp == MAP_FAILED)
+        errExit("mmap");
+\&
+    /* Copy data into the shared memory object. */
+\&
+    shmp\->cnt = len;
+    memcpy(&shmp\->buf, string, len);
+\&
+    /* Tell peer that it can now access shared memory. */
+\&
+    if (sem_post(&shmp\->sem1) == \-1)
+        errExit("sem_post");
+\&
+    /* Wait until peer says that it has finished accessing
+       the shared memory. */
+\&
+    if (sem_wait(&shmp\->sem2) == \-1)
+        errExit("sem_wait");
+\&
+    /* Write modified data in shared memory to standard output. */
+\&
+    write(STDOUT_FILENO, &shmp\->buf, len);
+    write(STDOUT_FILENO, "\en", 1);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR close (2),
+.BR fchmod (2),
+.BR fchown (2),
+.BR fcntl (2),
+.BR fstat (2),
+.BR ftruncate (2),
+.BR memfd_create (2),
+.BR mmap (2),
+.BR open (2),
+.BR umask (2),
+.BR shm_overview (7)
diff --git a/man/man3/shm_unlink.3 b/man/man3/shm_unlink.3
new file mode 100644
index 000000000..74f298654
--- /dev/null
+++ b/man/man3/shm_unlink.3
@@ -0,0 +1 @@
+.so man3/shm_open.3
diff --git a/man/man3/sigabbrev_np.3 b/man/man3/sigabbrev_np.3
new file mode 100644
index 000000000..f64f75692
--- /dev/null
+++ b/man/man3/sigabbrev_np.3
@@ -0,0 +1 @@
+.so man3/strsignal.3
diff --git a/man/man3/sigaddset.3 b/man/man3/sigaddset.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigaddset.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/sigandset.3 b/man/man3/sigandset.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigandset.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/sigblock.3 b/man/man3/sigblock.3
new file mode 100644
index 000000000..5582b115f
--- /dev/null
+++ b/man/man3/sigblock.3
@@ -0,0 +1 @@
+.so man3/sigvec.3
diff --git a/man/man3/sigdelset.3 b/man/man3/sigdelset.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigdelset.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/sigdescr_np.3 b/man/man3/sigdescr_np.3
new file mode 100644
index 000000000..f64f75692
--- /dev/null
+++ b/man/man3/sigdescr_np.3
@@ -0,0 +1 @@
+.so man3/strsignal.3
diff --git a/man/man3/sigemptyset.3 b/man/man3/sigemptyset.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigemptyset.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/sigfillset.3 b/man/man3/sigfillset.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigfillset.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/siggetmask.3 b/man/man3/siggetmask.3
new file mode 100644
index 000000000..5582b115f
--- /dev/null
+++ b/man/man3/siggetmask.3
@@ -0,0 +1 @@
+.so man3/sigvec.3
diff --git a/man/man3/sighold.3 b/man/man3/sighold.3
new file mode 100644
index 000000000..c4e1d3caa
--- /dev/null
+++ b/man/man3/sighold.3
@@ -0,0 +1 @@
+.so man3/sigset.3
diff --git a/man/man3/sigignore.3 b/man/man3/sigignore.3
new file mode 100644
index 000000000..c4e1d3caa
--- /dev/null
+++ b/man/man3/sigignore.3
@@ -0,0 +1 @@
+.so man3/sigset.3
diff --git a/man/man3/siginterrupt.3 b/man/man3/siginterrupt.3
new file mode 100644
index 000000000..ddb9aa3c6
--- /dev/null
+++ b/man/man3/siginterrupt.3
@@ -0,0 +1,98 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:40:51 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Apr 14 16:20:34 1996 by Andries Brouwer (aeb@cwi.nl)
+.TH siginterrupt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+siginterrupt \- allow signals to interrupt system calls
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "[[deprecated]] int siginterrupt(int " sig ", int " flag );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR siginterrupt ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc <= 2.19: */ _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR siginterrupt ()
+function changes the restart behavior when
+a system call is interrupted by the signal \fIsig\fP.
+If the \fIflag\fP
+argument is false (0), then system calls will be restarted if interrupted
+by the specified signal \fIsig\fP.
+This is the default behavior in Linux.
+.P
+If the \fIflag\fP argument is true (1) and no data has been transferred,
+then a system call interrupted by the signal \fIsig\fP will return \-1
+and \fIerrno\fP will be set to
+.BR EINTR .
+.P
+If the \fIflag\fP argument is true (1) and data transfer has started,
+then the system call will be interrupted and will return the actual
+amount of data transferred.
+.SH RETURN VALUE
+The
+.BR siginterrupt ()
+function returns 0 on success.
+It returns \-1 if the
+signal number
+.I sig
+is invalid, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+The specified signal number is invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR siginterrupt ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe const:sigintr
+T}
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+4.3BSD, POSIX.1-2001.
+Obsolete in POSIX.1-2008,
+recommending the use of
+.BR sigaction (2)
+with the
+.B SA_RESTART
+flag instead.
+.SH SEE ALSO
+.BR signal (2)
diff --git a/man/man3/sigisemptyset.3 b/man/man3/sigisemptyset.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigisemptyset.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/sigismember.3 b/man/man3/sigismember.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigismember.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/siglongjmp.3 b/man/man3/siglongjmp.3
new file mode 100644
index 000000000..7cf497fc3
--- /dev/null
+++ b/man/man3/siglongjmp.3
@@ -0,0 +1 @@
+.so man3/setjmp.3
diff --git a/man/man3/sigmask.3 b/man/man3/sigmask.3
new file mode 100644
index 000000000..5582b115f
--- /dev/null
+++ b/man/man3/sigmask.3
@@ -0,0 +1 @@
+.so man3/sigvec.3
diff --git a/man/man3/signbit.3 b/man/man3/signbit.3
new file mode 100644
index 000000000..0a54b70b7
--- /dev/null
+++ b/man/man3/signbit.3
@@ -0,0 +1,79 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Based on glibc infopages, copyright Free Software Foundation
+.\"
+.TH signbit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+signbit \- test sign of a real floating-point number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B "#include <math.h>"
+.P
+.BI  "int signbit(" x ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR signbit ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.BR signbit ()
+is a generic macro which can work on all real floating-point types.
+It returns a nonzero value if the value of
+.I x
+has its sign bit set.
+.P
+This is not the same as
+.IR "x < 0.0" ,
+because IEEE 754 floating point allows zero to be signed.
+The comparison
+.I \-0.0\~<\~0.0
+is false, but
+.I signbit(\-0.0)
+will return a nonzero value.
+.P
+NaNs and infinities have a sign bit.
+.SH RETURN VALUE
+The
+.BR signbit ()
+macro returns nonzero if the sign of
+.I x
+is negative; otherwise it returns zero.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR signbit ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.P
+This function is defined in IEC 559 (and the appendix with
+recommended functions in IEEE 754/IEEE 854).
+.SH SEE ALSO
+.BR copysign (3)
diff --git a/man/man3/signgam.3 b/man/man3/signgam.3
new file mode 100644
index 000000000..be0ed98e0
--- /dev/null
+++ b/man/man3/signgam.3
@@ -0,0 +1 @@
+.so man3/lgamma.3
diff --git a/man/man3/significand.3 b/man/man3/significand.3
new file mode 100644
index 000000000..f835f5511
--- /dev/null
+++ b/man/man3/significand.3
@@ -0,0 +1,78 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" heavily based on glibc infopages, copyright Free Software Foundation
+.\"
+.TH significand 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+significand, significandf, significandl \-
+get mantissa of floating-point number
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double significand(double " x );
+.BI "float significandf(float " x );
+.BI "long double significandl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR significand (),
+.BR significandf (),
+.BR significandl ():
+.nf
+    /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the mantissa of
+.I x
+scaled to the range
+.RB [ 1 ,\~ FLT_RADIX ).
+They are equivalent to
+.P
+.in +4n
+.EX
+scalb(x, (double) \-ilogb(x))
+.EE
+.in
+.P
+This function exists mainly for use in certain standardized tests
+for IEEE 754 conformance.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR significand (),
+.BR significandf (),
+.BR significandl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.TP
+.BR significand ()
+BSD.
+.SH HISTORY
+.TP
+.BR significand ()
+BSD.
+.SH SEE ALSO
+.BR ilogb (3),
+.BR scalb (3)
diff --git a/man/man3/significandf.3 b/man/man3/significandf.3
new file mode 100644
index 000000000..4ae39f580
--- /dev/null
+++ b/man/man3/significandf.3
@@ -0,0 +1 @@
+.so man3/significand.3
diff --git a/man/man3/significandl.3 b/man/man3/significandl.3
new file mode 100644
index 000000000..4ae39f580
--- /dev/null
+++ b/man/man3/significandl.3
@@ -0,0 +1 @@
+.so man3/significand.3
diff --git a/man/man3/sigorset.3 b/man/man3/sigorset.3
new file mode 100644
index 000000000..c73078101
--- /dev/null
+++ b/man/man3/sigorset.3
@@ -0,0 +1 @@
+.so man3/sigsetops.3
diff --git a/man/man3/sigpause.3 b/man/man3/sigpause.3
new file mode 100644
index 000000000..7c1d78d3f
--- /dev/null
+++ b/man/man3/sigpause.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright (C) 2004 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sigpause 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigpause \- atomically release blocked signals and wait for interrupt
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "[[deprecated]] int sigpause(int " sigmask ");  /* BSD (but see NOTES) */"
+.P
+.BI "[[deprecated]] int sigpause(int " sig ");      /* POSIX.1 / SysV / UNIX 95 */"
+.fi
+.SH DESCRIPTION
+Don't use this function.
+Use
+.BR sigsuspend (2)
+instead.
+.P
+The function
+.BR sigpause ()
+is designed to wait for some signal.
+It changes the process's signal mask (set of blocked signals),
+and then waits for a signal to arrive.
+Upon arrival of a signal, the original signal mask is restored.
+.SH RETURN VALUE
+If
+.BR sigpause ()
+returns, it was interrupted by a signal and the return value is \-1
+with
+.I errno
+set to
+.BR EINTR .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sigpause ()
+T}	Thread safety	MT-Safe
+.TE
+.\" FIXME: The marking is different from that in the glibc manual,
+.\" marking in glibc manual is more detailed:
+.\"
+.\" sigpause: MT-Unsafe race:sigprocmask/!bsd!linux
+.\"
+.\" glibc manual says /!linux!bsd indicate the preceding marker only applies
+.\" when the underlying kernel is neither Linux nor a BSD kernel.
+.\" So, it is safe in Linux kernel.
+.SH VERSIONS
+On Linux, this routine is a system call only on the Sparc (sparc64)
+architecture.
+.P
+.\" Libc4 and libc5 know only about the BSD version.
+.\"
+glibc uses the BSD version if the
+.B _BSD_SOURCE
+feature test macro is defined and none of
+.BR _POSIX_SOURCE ,
+.BR _POSIX_C_SOURCE ,
+.BR _XOPEN_SOURCE ,
+.BR _GNU_SOURCE ,
+or
+.B _SVID_SOURCE
+is defined.
+Otherwise, the System V version is used,
+and feature test macros must be defined as follows to obtain the declaration:
+.IP \[bu] 3
+Since glibc 2.26:
+_XOPEN_SOURCE >= 500
+.\" || (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+.IP \[bu]
+glibc 2.25 and earlier: _XOPEN_SOURCE
+.P
+Since glibc 2.19, only the System V version is exposed by
+.IR <signal.h> ;
+applications that formerly used the BSD
+.BR sigpause ()
+should be amended to use
+.BR sigsuspend (2).
+.\"
+.\" For the BSD version, one usually uses a zero
+.\" .I sigmask
+.\" to indicate that no signals are to be blocked.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+Obsoleted in POSIX.1-2008.
+.P
+The classical BSD version of this function appeared in 4.2BSD.
+It sets the process's signal mask to
+.IR sigmask .
+UNIX 95 standardized the incompatible System V version of
+this function, which removes only the specified signal
+.I sig
+from the process's signal mask.
+.\" __xpg_sigpause: UNIX 95, spec 1170, SVID, SVr4, XPG
+The unfortunate situation with two incompatible functions with the
+same name was solved by the
+.BR \%sigsuspend (2)
+function, that takes a
+.I "sigset_t\ *"
+argument (instead of an
+.IR int ).
+.SH SEE ALSO
+.BR kill (2),
+.BR sigaction (2),
+.BR sigprocmask (2),
+.BR sigsuspend (2),
+.BR sigblock (3),
+.BR sigvec (3),
+.BR feature_test_macros (7)
diff --git a/man/man3/sigqueue.3 b/man/man3/sigqueue.3
new file mode 100644
index 000000000..3d8c78736
--- /dev/null
+++ b/man/man3/sigqueue.3
@@ -0,0 +1,162 @@
+'\" t
+.\" Copyright (c) 2002 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" added note on self-signaling, aeb, 2002-06-07
+.\" added note on CAP_KILL, mtk, 2004-06-16
+.\"
+.TH sigqueue 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigqueue \- queue a signal and data to a process
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigqueue(pid_t " pid ", int " sig ", const union sigval " value );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigqueue ():
+.nf
+    _POSIX_C_SOURCE >= 199309L
+.fi
+.SH DESCRIPTION
+.BR sigqueue ()
+sends the signal specified in
+.I sig
+to the process whose PID is given in
+.IR pid .
+The permissions required to send a signal are the same as for
+.BR kill (2).
+As with
+.BR kill (2),
+the null signal (0) can be used to check if a process with a given
+PID exists.
+.P
+The
+.I value
+argument is used to specify an accompanying item of data (either an integer
+or a pointer value) to be sent with the signal, and has the following type:
+.P
+.in +4n
+.EX
+union sigval {
+    int   sival_int;
+    void *sival_ptr;
+};
+.EE
+.in
+.P
+If the receiving process has installed a handler for this signal using the
+.B SA_SIGINFO
+flag to
+.BR sigaction (2),
+then it can obtain this data via the
+.I si_value
+field of the
+.I siginfo_t
+structure passed as the second argument to the handler.
+Furthermore, the
+.I si_code
+field of that structure will be set to
+.BR SI_QUEUE .
+.SH RETURN VALUE
+On success,
+.BR sigqueue ()
+returns 0, indicating that the signal was successfully
+queued to the receiving process.
+Otherwise, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EAGAIN
+The limit of signals which may be queued has been reached.
+(See
+.BR signal (7)
+for further information.)
+.TP
+.B EINVAL
+.I sig
+was invalid.
+.TP
+.B EPERM
+The process does not have permission to send the signal
+to the receiving process.
+For the required permissions, see
+.BR kill (2).
+.TP
+.B ESRCH
+No process has a PID matching
+.IR pid .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sigqueue ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.SS C library/kernel differences
+On Linux,
+.BR sigqueue ()
+is implemented using the
+.BR rt_sigqueueinfo (2)
+system call.
+The system call differs in its third argument, which is the
+.I siginfo_t
+structure that will be supplied to the receiving process's
+signal handler or returned by the receiving process's
+.BR sigtimedwait (2)
+call.
+Inside the glibc
+.BR sigqueue ()
+wrapper, this argument,
+.IR uinfo ,
+is initialized as follows:
+.P
+.in +4n
+.EX
+uinfo.si_signo = sig;      /* Argument supplied to sigqueue() */
+uinfo.si_code = SI_QUEUE;
+uinfo.si_pid = getpid();   /* Process ID of sender */
+uinfo.si_uid = getuid();   /* Real UID of sender */
+uinfo.si_value = val;      /* Argument supplied to sigqueue() */
+.EE
+.in
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+Linux 2.2.
+POSIX.1-2001.
+.SH NOTES
+If this function results in the sending of a signal to the process
+that invoked it, and that signal was not blocked by the calling thread,
+and no other threads were willing to handle this signal (either by
+having it unblocked, or by waiting for it using
+.BR sigwait (3)),
+then at least some signal must be delivered to this thread before this
+function returns.
+.SH SEE ALSO
+.BR kill (2),
+.BR rt_sigqueueinfo (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR pthread_sigqueue (3),
+.BR sigwait (3),
+.BR signal (7)
diff --git a/man/man3/sigrelse.3 b/man/man3/sigrelse.3
new file mode 100644
index 000000000..c4e1d3caa
--- /dev/null
+++ b/man/man3/sigrelse.3
@@ -0,0 +1 @@
+.so man3/sigset.3
diff --git a/man/man3/sigset.3 b/man/man3/sigset.3
new file mode 100644
index 000000000..8613710c0
--- /dev/null
+++ b/man/man3/sigset.3
@@ -0,0 +1,265 @@
+'\" t
+.\" Copyright (c) 2005 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sigset 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigset, sighold, sigrelse, sigignore \- System V signal API
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.B typedef void (*sighandler_t)(int);
+.P
+.BI "[[deprecated]] sighandler_t sigset(int " sig ", sighandler_t " disp );
+.P
+.BI "[[deprecated]] int sighold(int " sig );
+.BI "[[deprecated]] int sigrelse(int " sig );
+.BI "[[deprecated]] int sigignore(int " sig );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigset (),
+.BR sighold (),
+.BR sigrelse (),
+.BR sigignore ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+These functions are provided in glibc as a compatibility interface
+for programs that make use of the historical System V signal API.
+This API is obsolete: new applications should use the POSIX signal API
+.RB ( sigaction (2),
+.BR sigprocmask (2),
+etc.)
+.P
+The
+.BR sigset ()
+function modifies the disposition of the signal
+.IR sig .
+The
+.I disp
+argument can be the address of a signal handler function,
+or one of the following constants:
+.TP
+.B SIG_DFL
+Reset the disposition of
+.I sig
+to the default.
+.TP
+.B SIG_IGN
+Ignore
+.IR sig .
+.TP
+.B SIG_HOLD
+Add
+.I sig
+to the process's signal mask, but leave the disposition of
+.I sig
+unchanged.
+.P
+If
+.I disp
+specifies the address of a signal handler, then
+.I sig
+is added to the process's signal mask during execution of the handler.
+.P
+If
+.I disp
+was specified as a value other than
+.BR SIG_HOLD ,
+then
+.I sig
+is removed from the process's signal mask.
+.P
+The dispositions for
+.B SIGKILL
+and
+.B SIGSTOP
+cannot be changed.
+.P
+The
+.BR sighold ()
+function adds
+.I sig
+to the calling process's signal mask.
+.P
+The
+.BR sigrelse ()
+function removes
+.I sig
+from the calling process's signal mask.
+.P
+The
+.BR sigignore ()
+function sets the disposition of
+.I sig
+to
+.BR SIG_IGN .
+.SH RETURN VALUE
+On success,
+.BR sigset ()
+returns
+.B SIG_HOLD
+if
+.I sig
+was blocked before the call,
+or the signal's previous disposition
+if it was not blocked before the call.
+On error,
+.BR sigset ()
+returns \-1, with
+.I errno
+set to indicate the error.
+(But see BUGS below.)
+.P
+The
+.BR sighold (),
+.BR sigrelse (),
+and
+.BR sigignore ()
+functions return 0 on success; on error, these functions return \-1 and set
+.I errno
+to indicate the error.
+.SH ERRORS
+For
+.BR sigset ()
+see the ERRORS under
+.BR sigaction (2)
+and
+.BR sigprocmask (2).
+.P
+For
+.BR sighold ()
+and
+.BR sigrelse ()
+see the ERRORS under
+.BR sigprocmask (2).
+.P
+For
+.BR sigignore (),
+see the errors under
+.BR sigaction (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sigset (),
+.BR sighold (),
+.BR sigrelse (),
+.BR sigignore ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.TP
+.I sighandler_t
+GNU.
+POSIX.1 uses the same type but without a
+.IR typedef .
+.SH HISTORY
+glibc 2.1.
+SVr4, POSIX.1-2001.
+POSIX.1-2008 marks these functions
+as obsolete, recommending the use of
+.BR sigaction (2),
+.BR sigprocmask (2),
+.BR pthread_sigmask (3),
+and
+.BR sigsuspend (2)
+instead.
+.SH NOTES
+The
+.BR sigset ()
+function provides reliable signal handling semantics (as when calling
+.BR sigaction (2)
+with
+.I sa_mask
+equal to 0).
+.P
+On System V, the
+.BR signal ()
+function provides unreliable semantics (as when calling
+.BR sigaction (2)
+with
+.I sa_mask
+equal to
+.IR "SA_RESETHAND | SA_NODEFER" ).
+On BSD,
+.BR signal ()
+provides reliable semantics.
+POSIX.1-2001 leaves these aspects of
+.BR signal ()
+unspecified.
+See
+.BR signal (2)
+for further details.
+.P
+In order to wait for a signal,
+BSD and System V both provided a function named
+.BR sigpause (3),
+but this function has a different argument on the two systems.
+See
+.BR sigpause (3)
+for details.
+.SH BUGS
+Before glibc 2.2,
+.BR sigset ()
+did not unblock
+.I sig
+if
+.I disp
+was specified as a value other than
+.BR SIG_HOLD .
+.P
+Before glibc 2.5,
+.BR sigset ()
+does not correctly return the previous disposition of the signal
+in two cases.
+First, if
+.I disp
+is specified as
+.BR SIG_HOLD ,
+then a successful
+.BR sigset ()
+always returns
+.BR SIG_HOLD .
+Instead, it should return the previous disposition of the signal
+(unless the signal was blocked, in which case
+.B SIG_HOLD
+should be returned).
+Second, if the signal is currently blocked, then
+the return value of a successful
+.BR sigset ()
+should be
+.BR SIG_HOLD .
+Instead, the previous disposition of the signal is returned.
+These problems have been fixed since glibc 2.5.
+.\" See http://sourceware.org/bugzilla/show_bug.cgi?id=1951
+.SH SEE ALSO
+.BR kill (2),
+.BR pause (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR sigprocmask (2),
+.BR raise (3),
+.BR sigpause (3),
+.BR sigvec (3),
+.BR signal (7)
diff --git a/man/man3/sigsetjmp.3 b/man/man3/sigsetjmp.3
new file mode 100644
index 000000000..7cf497fc3
--- /dev/null
+++ b/man/man3/sigsetjmp.3
@@ -0,0 +1 @@
+.so man3/setjmp.3
diff --git a/man/man3/sigsetmask.3 b/man/man3/sigsetmask.3
new file mode 100644
index 000000000..5582b115f
--- /dev/null
+++ b/man/man3/sigsetmask.3
@@ -0,0 +1 @@
+.so man3/sigvec.3
diff --git a/man/man3/sigsetops.3 b/man/man3/sigsetops.3
new file mode 100644
index 000000000..cbdfa3299
--- /dev/null
+++ b/man/man3/sigsetops.3
@@ -0,0 +1,190 @@
+'\" t
+.\" Copyright (c) 1994 Mike Battersby
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified by aeb, 960721
+.\" 2005-11-21, mtk, added descriptions of sigisemptyset(), sigandset(),
+.\"                  and sigorset()
+.\" 2007-10-26 mdw   added wording that a sigset_t must be initialized
+.\"                  prior to use
+.\"
+.TH SIGSETOPS 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigemptyset, sigfillset, sigaddset, sigdelset, sigismember \- POSIX
+signal set operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigemptyset(sigset_t *" set );
+.BI "int sigfillset(sigset_t *" set );
+.P
+.BI "int sigaddset(sigset_t *" set ", int " signum );
+.BI "int sigdelset(sigset_t *" set ", int " signum );
+.P
+.BI "int sigismember(const sigset_t *" set ", int " signum );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigemptyset (),
+.BR sigfillset (),
+.BR sigaddset (),
+.BR sigdelset (),
+.BR sigismember ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+These functions allow the manipulation of POSIX signal sets.
+.P
+.BR sigemptyset ()
+initializes the signal set given by
+.I set
+to empty, with all signals excluded from the set.
+.P
+.BR sigfillset ()
+initializes
+.I set
+to full, including all signals.
+.P
+.BR sigaddset ()
+and
+.BR sigdelset ()
+add and delete respectively signal
+.I signum
+from
+.IR set .
+.P
+.BR sigismember ()
+tests whether
+.I signum
+is a member of
+.IR set .
+.P
+Objects of type
+.I sigset_t
+must be initialized by a call to either
+.BR sigemptyset ()
+or
+.BR sigfillset ()
+before being passed to the functions
+.BR sigaddset (),
+.BR sigdelset (),
+and
+.BR sigismember ()
+or the additional glibc functions described below
+.RB ( sigisemptyset (),
+.BR sigandset (),
+and
+.BR sigorset ()).
+The results are undefined if this is not done.
+.SH RETURN VALUE
+.BR sigemptyset (),
+.BR sigfillset (),
+.BR sigaddset (),
+and
+.BR sigdelset ()
+return 0 on success and \-1 on error.
+.P
+.BR sigismember ()
+returns 1 if
+.I signum
+is a member of
+.IR set ,
+0 if
+.I signum
+is not a member, and \-1 on error.
+.P
+On error, these functions set
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I signum
+is not a valid signal.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sigemptyset (),
+.BR sigfillset (),
+.BR sigaddset (),
+.BR sigdelset (),
+.BR sigismember (),
+.BR sigisemptyset (),
+.BR sigorset (),
+.BR sigandset ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.SS GNU
+If the
+.B _GNU_SOURCE
+feature test macro is defined, then \fI<signal.h>\fP
+exposes three other functions for manipulating signal
+sets:
+.P
+.nf
+.BI "int sigisemptyset(const sigset_t *" set );
+.BI "int sigorset(sigset_t *" dest ", const sigset_t *" left ,
+.BI "              const sigset_t *" right );
+.BI "int sigandset(sigset_t *" dest ", const sigset_t *" left ,
+.BI "              const sigset_t *" right );
+.fi
+.P
+.BR sigisemptyset ()
+returns 1 if
+.I set
+contains no signals, and 0 otherwise.
+.P
+.BR sigorset ()
+places the union of the sets
+.I left
+and
+.I right
+in
+.IR dest .
+.BR sigandset ()
+places the intersection of the sets
+.I left
+and
+.I right
+in
+.IR dest .
+Both functions return 0 on success, and \-1 on failure.
+.P
+These functions are nonstandard (a few other systems provide similar
+functions) and their use should be avoided in portable applications.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+When creating a filled signal set, the glibc
+.BR sigfillset ()
+function does not include the two real-time signals used internally
+by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.SH SEE ALSO
+.BR sigaction (2),
+.BR sigpending (2),
+.BR sigprocmask (2),
+.BR sigsuspend (2)
diff --git a/man/man3/sigstack.3 b/man/man3/sigstack.3
new file mode 100644
index 000000000..bf8596149
--- /dev/null
+++ b/man/man3/sigstack.3
@@ -0,0 +1,3 @@
+.so man2/sigaltstack.2
+.\" No new programs should use sigstack(3).
+.\" sigaltstack(2) briefly discusses sigstack(3), so point the user there.
diff --git a/man/man3/sigvec.3 b/man/man3/sigvec.3
new file mode 100644
index 000000000..3aa18980e
--- /dev/null
+++ b/man/man3/sigvec.3
@@ -0,0 +1,282 @@
+'\" t
+.\" Copyright (c) 2005 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sigvec 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigvec, sigblock, sigsetmask, siggetmask, sigmask \- BSD signal API
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "[[deprecated]] int sigvec(int " sig ", const struct sigvec *" vec ,
+.BI "                          struct sigvec *" ovec );
+.P
+.BI "[[deprecated]] int sigmask(int " signum );
+.P
+.BI "[[deprecated]] int sigblock(int " mask );
+.BI "[[deprecated]] int sigsetmask(int " mask );
+.B [[deprecated]] int siggetmask(void);
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+These functions are provided in glibc as a compatibility interface
+for programs that make use of the historical BSD signal API.
+This API is obsolete: new applications should use the POSIX signal API
+.RB ( sigaction (2),
+.BR sigprocmask (2),
+etc.).
+.P
+The
+.BR sigvec ()
+function sets and/or gets the disposition of the signal
+.I sig
+(like the POSIX
+.BR sigaction (2)).
+If
+.I vec
+is not NULL, it points to a
+.I sigvec
+structure that defines the new disposition for
+.IR sig .
+If
+.I ovec
+is not NULL, it points to a
+.I sigvec
+structure that is used to return the previous disposition of
+.IR sig .
+To obtain the current disposition of
+.I sig
+without changing it, specify NULL for
+.IR vec ,
+and a non-null pointer for
+.IR ovec .
+.P
+The dispositions for
+.B SIGKILL
+and
+.B SIGSTOP
+cannot be changed.
+.P
+The
+.I sigvec
+structure has the following form:
+.P
+.in +4n
+.EX
+struct sigvec {
+    void (*sv_handler)(int); /* Signal disposition */
+    int    sv_mask;          /* Signals to be blocked in handler */
+    int    sv_flags;         /* Flags */
+};
+.EE
+.in
+.P
+The
+.I sv_handler
+field specifies the disposition of the signal, and is either:
+the address of a signal handler function;
+.BR SIG_DFL ,
+meaning the default disposition applies for the signal; or
+.BR SIG_IGN ,
+meaning that the signal is ignored.
+.P
+If
+.I sv_handler
+specifies the address of a signal handler, then
+.I sv_mask
+specifies a mask of signals that are to be blocked while
+the handler is executing.
+In addition, the signal for which the handler is invoked is
+also blocked.
+Attempts to block
+.B SIGKILL
+or
+.B SIGSTOP
+are silently ignored.
+.P
+If
+.I sv_handler
+specifies the address of a signal handler, then the
+.I sv_flags
+field specifies flags controlling what happens when the handler is called.
+This field may contain zero or more of the following flags:
+.TP
+.B SV_INTERRUPT
+If the signal handler interrupts a blocking system call,
+then upon return from the handler the system call is not restarted:
+instead it fails with the error
+.BR EINTR .
+If this flag is not specified, then system calls are restarted
+by default.
+.TP
+.B SV_RESETHAND
+Reset the disposition of the signal to the default
+before calling the signal handler.
+If this flag is not specified, then the handler remains established
+until explicitly removed by a later call to
+.BR sigvec ()
+or until the process performs an
+.BR execve (2).
+.TP
+.B SV_ONSTACK
+Handle the signal on the alternate signal stack
+(historically established under BSD using the obsolete
+.BR sigstack ()
+function; the POSIX replacement is
+.BR sigaltstack (2)).
+.P
+The
+.BR sigmask ()
+macro constructs and returns a "signal mask" for
+.IR signum .
+For example, we can initialize the
+.I vec.sv_mask
+field given to
+.BR sigvec ()
+using code such as the following:
+.P
+.in +4n
+.EX
+vec.sv_mask = sigmask(SIGQUIT) | sigmask(SIGABRT);
+            /* Block SIGQUIT and SIGABRT during
+               handler execution */
+.EE
+.in
+.P
+The
+.BR sigblock ()
+function adds the signals in
+.I mask
+to the process's signal mask
+(like POSIX
+.IR sigprocmask(SIG_BLOCK) ),
+and returns the process's previous signal mask.
+Attempts to block
+.B SIGKILL
+or
+.B SIGSTOP
+are silently ignored.
+.P
+The
+.BR sigsetmask ()
+function sets the process's signal mask to the value given in
+.I mask
+(like POSIX
+.IR sigprocmask(SIG_SETMASK) ),
+and returns the process's previous signal mask.
+.P
+The
+.BR siggetmask ()
+function returns the process's current signal mask.
+This call is equivalent to
+.IR sigblock(0) .
+.SH RETURN VALUE
+The
+.BR sigvec ()
+function returns 0 on success; on error, it returns \-1 and sets
+.I errno
+to indicate the error.
+.P
+The
+.BR sigblock ()
+and
+.BR sigsetmask ()
+functions return the previous signal mask.
+.P
+The
+.BR sigmask ()
+macro returns the signal mask for
+.IR signum .
+.SH ERRORS
+See the ERRORS under
+.BR sigaction (2)
+and
+.BR sigprocmask (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sigvec (),
+.BR sigmask (),
+.BR sigblock (),
+.BR sigsetmask (),
+.BR siggetmask ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+.TP
+.BR sigvec ()
+.TQ
+.BR sigblock ()
+.TQ
+.BR sigmask ()
+.TQ
+.BR sigsetmask ()
+4.3BSD.
+.TP
+.BR siggetmask ()
+Unclear origin.
+.TP
+.BR sigvec ()
+Removed in glibc 2.21.
+.SH NOTES
+On 4.3BSD, the
+.BR signal ()
+function provided reliable semantics (as when calling
+.BR sigvec ()
+with
+.I vec.sv_mask
+equal to 0).
+On System V,
+.BR signal ()
+provides unreliable semantics.
+POSIX.1 leaves these aspects of
+.BR signal ()
+unspecified.
+See
+.BR signal (2)
+for further details.
+.P
+In order to wait for a signal,
+BSD and System V both provided a function named
+.BR sigpause (3),
+but this function has a different argument on the two systems.
+See
+.BR sigpause (3)
+for details.
+.SH SEE ALSO
+.BR kill (2),
+.BR pause (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR sigprocmask (2),
+.BR raise (3),
+.BR sigpause (3),
+.BR sigset (3),
+.BR signal (7)
diff --git a/man/man3/sigwait.3 b/man/man3/sigwait.3
new file mode 100644
index 000000000..2c3330015
--- /dev/null
+++ b/man/man3/sigwait.3
@@ -0,0 +1,112 @@
+'\" t
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sigwait 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigwait \- wait for a signal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.BI "int sigwait(const sigset_t *restrict " set ", int *restrict " sig );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigwait ():
+.nf
+    Since glibc 2.26:
+        _POSIX_C_SOURCE >= 199506L
+    glibc 2.25 and earlier:
+        _POSIX_C_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR sigwait ()
+function suspends execution of the calling thread until
+one of the signals specified in the signal set
+.I set
+becomes pending.
+For a signal to become pending,
+it must first be blocked with
+.BR sigprocmask (2).
+The function accepts the signal
+(removes it from the pending list of signals),
+and returns the signal number in
+.IR sig .
+.P
+The operation of
+.BR sigwait ()
+is the same as
+.BR sigwaitinfo (2),
+except that:
+.IP \[bu] 3
+.BR sigwait ()
+returns only the signal number, rather than a
+.I siginfo_t
+structure describing the signal.
+.IP \[bu]
+The return values of the two functions are different.
+.SH RETURN VALUE
+On success,
+.BR sigwait ()
+returns 0.
+On error, it returns a positive error number (listed in ERRORS).
+.SH ERRORS
+.TP
+.B EINVAL
+.\" Does not occur for glibc.
+.I set
+contains an invalid signal number.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sigwait ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+.BR sigwait ()
+is implemented using
+.BR sigtimedwait (2);
+consult its
+.BR NOTES .
+.P
+The glibc implementation of
+.BR sigwait ()
+silently ignores attempts to wait for the two real-time signals that
+are used internally by the NPTL threading implementation.
+See
+.BR nptl (7)
+for details.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+See
+.BR pthread_sigmask (3).
+.SH SEE ALSO
+.BR sigaction (2),
+.BR signalfd (2),
+.BR sigpending (2),
+.BR sigsuspend (2),
+.BR sigwaitinfo (2),
+.BR sigsetops (3),
+.BR signal (7)
diff --git a/man/man3/simpleq.3 b/man/man3/simpleq.3
new file mode 100644
index 000000000..fbb71f02c
--- /dev/null
+++ b/man/man3/simpleq.3
@@ -0,0 +1 @@
+.so man3/stailq.3
diff --git a/man/man3/sin.3 b/man/man3/sin.3
new file mode 100644
index 000000000..ba96f51a0
--- /dev/null
+++ b/man/man3/sin.3
@@ -0,0 +1,122 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH sin 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sin, sinf, sinl \- sine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double sin(double " x );
+.BI "float sinf(float " x );
+.BI "long double sinl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sinf (),
+.BR sinl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the sine of
+.IR x ,
+where
+.I x
+is
+given in radians.
+.SH RETURN VALUE
+On success, these functions return the sine of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is positive infinity or negative infinity,
+a domain error occurs,
+and a NaN is returned.
+.\"
+.\" POSIX.1 allows an optional range error for subnormal x
+.\" glibc 2.8 doesn't do this
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is an infinity
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sin (),
+.BR sinf (),
+.BR sinl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH BUGS
+Before glibc 2.10, the glibc implementation did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6781
+.I errno
+to
+.B EDOM
+when a domain error occurred.
+.SH SEE ALSO
+.BR acos (3),
+.BR asin (3),
+.BR atan (3),
+.BR atan2 (3),
+.BR cos (3),
+.BR csin (3),
+.BR sincos (3),
+.BR tan (3)
diff --git a/man/man3/sincos.3 b/man/man3/sincos.3
new file mode 100644
index 000000000..94bd1d93b
--- /dev/null
+++ b/man/man3/sincos.3
@@ -0,0 +1,112 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH sincos 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sincos, sincosf, sincosl \- calculate sin and cos simultaneously
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <math.h>
+.P
+.BI "void sincos(double " x ", double *" sin ", double *" cos );
+.BI "void sincosf(float " x ", float *" sin ", float *" cos );
+.BI "void sincosl(long double " x ", long double *" sin ", long double *" cos );
+.fi
+.SH DESCRIPTION
+Several applications need sine and cosine of the same angle
+.IR x .
+These functions compute both at the same time, and store the results in
+.I *sin
+and
+.IR *cos .
+Using this function can be more efficient than two separate calls to
+.BR sin (3)
+and
+.BR cos (3).
+.P
+If
+.I x
+is a NaN,
+a NaN is returned in
+.I *sin
+and
+.IR *cos .
+.P
+If
+.I x
+is positive infinity or negative infinity,
+a domain error occurs, and
+a NaN is returned in
+.I *sin
+and
+.IR *cos .
+.SH RETURN VALUE
+These functions return
+.IR void .
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is an infinity
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sincos (),
+.BR sincosf (),
+.BR sincosl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH HISTORY
+glibc 2.1.
+.SH NOTES
+To see the performance advantage of
+.BR sincos (),
+it may be necessary to disable
+.BR gcc (1)
+built-in optimizations, using flags such as:
+.P
+.in +4n
+.EX
+cc \-O \-lm \-fno\-builtin prog.c
+.EE
+.in
+.SH BUGS
+Before glibc 2.22, the glibc implementation did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=15467
+.I errno
+to
+.B EDOM
+when a domain error occurred.
+.SH SEE ALSO
+.BR cos (3),
+.BR sin (3),
+.BR tan (3)
diff --git a/man/man3/sincosf.3 b/man/man3/sincosf.3
new file mode 100644
index 000000000..9faef654f
--- /dev/null
+++ b/man/man3/sincosf.3
@@ -0,0 +1 @@
+.so man3/sincos.3
diff --git a/man/man3/sincosl.3 b/man/man3/sincosl.3
new file mode 100644
index 000000000..9faef654f
--- /dev/null
+++ b/man/man3/sincosl.3
@@ -0,0 +1 @@
+.so man3/sincos.3
diff --git a/man/man3/sinf.3 b/man/man3/sinf.3
new file mode 100644
index 000000000..eab51f4a7
--- /dev/null
+++ b/man/man3/sinf.3
@@ -0,0 +1 @@
+.so man3/sin.3
diff --git a/man/man3/sinh.3 b/man/man3/sinh.3
new file mode 100644
index 000000000..d9837b3eb
--- /dev/null
+++ b/man/man3/sinh.3
@@ -0,0 +1,129 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1996-06-08 by aeb
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH sinh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sinh, sinhf, sinhl \- hyperbolic sine function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double sinh(double " x );
+.BI "float sinhf(float " x );
+.BI "long double sinhl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sinhf (),
+.BR sinhl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the hyperbolic sine of
+.IR x ,
+which
+is defined mathematically as:
+.P
+.nf
+    sinh(x) = (exp(x) \- exp(\-x)) / 2
+.fi
+.SH RETURN VALUE
+On success, these functions return the hyperbolic sine of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0), +0 (\-0) is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity),
+positive infinity (negative infinity) is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the same sign as
+.IR x .
+.\"
+.\" POSIX.1-2001 documents an optional range error (underflow)
+.\" for subnormal x;
+.\" glibc 2.8 does not do this.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Range error: result overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sinh (),
+.BR sinhf (),
+.BR sinhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR acosh (3),
+.BR asinh (3),
+.BR atanh (3),
+.BR cosh (3),
+.BR csinh (3),
+.BR tanh (3)
diff --git a/man/man3/sinhf.3 b/man/man3/sinhf.3
new file mode 100644
index 000000000..dc3ce9415
--- /dev/null
+++ b/man/man3/sinhf.3
@@ -0,0 +1 @@
+.so man3/sinh.3
diff --git a/man/man3/sinhl.3 b/man/man3/sinhl.3
new file mode 100644
index 000000000..dc3ce9415
--- /dev/null
+++ b/man/man3/sinhl.3
@@ -0,0 +1 @@
+.so man3/sinh.3
diff --git a/man/man3/sinl.3 b/man/man3/sinl.3
new file mode 100644
index 000000000..eab51f4a7
--- /dev/null
+++ b/man/man3/sinl.3
@@ -0,0 +1 @@
+.so man3/sin.3
diff --git a/man/man3/sleep.3 b/man/man3/sleep.3
new file mode 100644
index 000000000..0cf235d90
--- /dev/null
+++ b/man/man3/sleep.3
@@ -0,0 +1,79 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 18:16:02 1993 by Rik Faith (faith@cs.unc.edu)
+.TH sleep 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sleep \- sleep for a specified number of seconds
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "unsigned int sleep(unsigned int " "seconds" );
+.fi
+.SH DESCRIPTION
+.BR sleep ()
+causes the calling thread to sleep either until
+the number of real-time seconds specified in
+.I seconds
+have elapsed or until a signal arrives which is not ignored.
+.SH RETURN VALUE
+Zero if the requested time has elapsed,
+or the number of seconds left to sleep,
+if the call was interrupted by a signal handler.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sleep ()
+T}	Thread safety	MT-Unsafe sig:SIGCHLD/linux
+.TE
+.SH VERSIONS
+On Linux,
+.BR sleep ()
+is implemented via
+.BR nanosleep (2).
+See the
+.BR nanosleep (2)
+man page for a discussion of the clock used.
+.P
+On some systems,
+.BR sleep ()
+may be implemented using
+.BR alarm (2)
+and
+.B SIGALRM
+(POSIX.1 permits this);
+mixing calls to
+.BR alarm (2)
+and
+.BR sleep ()
+is a bad idea.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH CAVEATS
+Using
+.BR longjmp (3)
+from a signal handler or modifying the handling of
+.B SIGALRM
+while sleeping will cause undefined results.
+.SH SEE ALSO
+.BR sleep (1),
+.BR alarm (2),
+.BR nanosleep (2),
+.BR signal (2),
+.BR signal (7)
diff --git a/man/man3/slist.3 b/man/man3/slist.3
new file mode 100644
index 000000000..02745286b
--- /dev/null
+++ b/man/man3/slist.3
@@ -0,0 +1,319 @@
+.\" Copyright (c) 1993
+.\"    The Regents of the University of California.  All rights reserved.
+.\" and Copyright (c) 2020 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"
+.TH SLIST 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+SLIST_EMPTY,
+SLIST_ENTRY,
+SLIST_FIRST,
+SLIST_FOREACH,
+.\"SLIST_FOREACH_FROM,
+.\"SLIST_FOREACH_FROM_SAFE,
+.\"SLIST_FOREACH_SAFE,
+SLIST_HEAD,
+SLIST_HEAD_INITIALIZER,
+SLIST_INIT,
+SLIST_INSERT_AFTER,
+SLIST_INSERT_HEAD,
+SLIST_NEXT,
+SLIST_REMOVE,
+.\"SLIST_REMOVE_AFTER,
+SLIST_REMOVE_HEAD
+.\"SLIST_SWAP
+\- implementation of a singly linked list
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/queue.h>
+.P
+.B SLIST_ENTRY(TYPE);
+.P
+.B SLIST_HEAD(HEADNAME, TYPE);
+.BI "SLIST_HEAD SLIST_HEAD_INITIALIZER(SLIST_HEAD " head );
+.BI "void SLIST_INIT(SLIST_HEAD *" head );
+.P
+.BI "int SLIST_EMPTY(SLIST_HEAD *" head );
+.P
+.BI "void SLIST_INSERT_HEAD(SLIST_HEAD *" head ,
+.BI "                        struct TYPE *" elm ", SLIST_ENTRY " NAME );
+.BI "void SLIST_INSERT_AFTER(struct TYPE *" listelm ,
+.BI "                        struct TYPE *" elm ", SLIST_ENTRY " NAME );
+.P
+.BI "struct TYPE *SLIST_FIRST(SLIST_HEAD *" head );
+.BI "struct TYPE *SLIST_NEXT(struct TYPE *" elm ", SLIST_ENTRY " NAME );
+.P
+.BI "SLIST_FOREACH(struct TYPE *" var ", SLIST_HEAD *" head ", SLIST_ENTRY " NAME );
+.\" .BI "SLIST_FOREACH_FROM(struct TYPE *" var ", SLIST_HEAD *" head ,
+.\" .BI "                        SLIST_ENTRY " NAME );
+.\" .P
+.\" .BI "SLIST_FOREACH_SAFE(struct TYPE *" var ", SLIST_HEAD *" head ,
+.\" .BI "                        SLIST_ENTRY " NAME ", struct TYPE *" temp_var );
+.\" .BI "SLIST_FOREACH_FROM_SAFE(struct TYPE *" var ", SLIST_HEAD *" head ,
+.\" .BI "                        SLIST_ENTRY " NAME ", struct TYPE *" temp_var );
+.P
+.BI "void SLIST_REMOVE(SLIST_HEAD *" head ", struct TYPE *" elm ,
+.BI "                        SLIST_ENTRY " NAME );
+.BI "void SLIST_REMOVE_HEAD(SLIST_HEAD *" head ,
+.BI "                        SLIST_ENTRY " NAME );
+.\" .BI "void SLIST_REMOVE_AFTER(struct TYPE *" elm ,
+.\" .BI "                        SLIST_ENTRY " NAME );
+.\" .P
+.\" .BI "void SLIST_SWAP(SLIST_HEAD *" head1 ", SLIST_HEAD *" head2 ,
+.\" .BI "                        SLIST_ENTRY " NAME );
+.fi
+.SH DESCRIPTION
+These macros define and operate on singly linked lists.
+.P
+In the macro definitions,
+.I TYPE
+is the name of a user-defined structure,
+that must contain a field of type
+.IR SLIST_ENTRY ,
+named
+.IR NAME .
+The argument
+.I HEADNAME
+is the name of a user-defined structure
+that must be declared using the macro
+.BR SLIST_HEAD ().
+.SS Creation
+A singly linked list is headed by a structure defined by the
+.BR SLIST_HEAD ()
+macro.
+This structure contains a single pointer to the first element on the list.
+The elements are singly linked
+for minimum space and pointer manipulation overhead
+at the expense of O(n) removal for arbitrary elements.
+New elements can be added to the list
+after an existing element
+or at the head of the list.
+An
+.I SLIST_HEAD
+structure is declared as follows:
+.P
+.in +4
+.EX
+SLIST_HEAD(HEADNAME, TYPE) head;
+.EE
+.in
+.P
+where
+.I struct HEADNAME
+is the structure to be defined, and
+.I struct TYPE
+is the type of the elements to be linked into the list.
+A pointer to the head of the list can later be declared as:
+.P
+.in +4
+.EX
+struct HEADNAME *headp;
+.EE
+.in
+.P
+(The names
+.I head
+and
+.I headp
+are user selectable.)
+.P
+.BR SLIST_ENTRY ()
+declares a structure that connects the elements in
+the list.
+.P
+.BR SLIST_HEAD_INITIALIZER ()
+evaluates to an initializer for the list
+.IR head .
+.P
+.BR SLIST_INIT ()
+initializes the list referenced by
+.IR head .
+.P
+.BR SLIST_EMPTY ()
+evaluates to true if there are no elements in the list.
+.SS Insertion
+.BR SLIST_INSERT_HEAD ()
+inserts the new element
+.I elm
+at the head of the list.
+.P
+.BR SLIST_INSERT_AFTER ()
+inserts the new element
+.I elm
+after the element
+.IR listelm .
+.SS Traversal
+.BR SLIST_FIRST ()
+returns the first element in the list, or NULL if the list is empty.
+.P
+.BR SLIST_NEXT ()
+returns the next element in the list.
+.P
+.BR SLIST_FOREACH ()
+traverses the list referenced by
+.I head
+in the forward direction,
+assigning each element in turn to
+.IR var .
+.\" .P
+.\" .BR SLIST_FOREACH_FROM ()
+.\" behaves identically to
+.\" .BR SLIST_FOREACH ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found SLIST element and begins the loop at
+.\" .I var
+.\" instead of the first element in the SLIST referenced by
+.\" .IR head .
+.\" .Pp
+.\" .BR SLIST_FOREACH_SAFE ()
+.\" traverses the list referenced by
+.\" .I head
+.\" in the forward direction, assigning each element in
+.\" turn to
+.\" .IR var .
+.\" However, unlike
+.\" .BR SLIST_FOREACH ()
+.\" here it is permitted to both remove
+.\" .I var
+.\" as well as free it from within the loop safely without interfering with the
+.\" traversal.
+.\" .P
+.\" .BR SLIST_FOREACH_FROM_SAFE ()
+.\" behaves identically to
+.\" .BR SLIST_FOREACH_SAFE ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found SLIST element and begins the loop at
+.\" .I var
+.\" instead of the first element in the SLIST referenced by
+.\" .IR head .
+.SS Removal
+.BR SLIST_REMOVE ()
+removes the element
+.I elm
+from the list.
+.P
+.BR SLIST_REMOVE_HEAD ()
+removes the element
+.I elm
+from the head of the list.
+For optimum efficiency,
+elements being removed from the head of the list
+should explicitly use this macro instead of the generic
+.BR SLIST_REMOVE ().
+.\" .P
+.\" .BR SLIST_REMOVE_AFTER ()
+.\" removes the element after
+.\" .I elm
+.\" from the list.
+.\" Unlike
+.\" .IR SLIST_REMOVE ,
+.\" this macro does not traverse the entire list.
+.\" .SS Other features
+.\" .BR SLIST_SWAP ()
+.\" swaps the contents of
+.\" .I head1
+.\" and
+.\" .IR head2 .
+.SH RETURN VALUE
+.BR SLIST_EMPTY ()
+returns nonzero if the list is empty,
+and zero if the list contains at least one entry.
+.P
+.BR SLIST_FIRST (),
+and
+.BR SLIST_NEXT ()
+return a pointer to the first or next
+.I TYPE
+structure, respectively.
+.P
+.BR SLIST_HEAD_INITIALIZER ()
+returns an initializer that can be assigned to the list
+.IR head .
+.SH STANDARDS
+BSD.
+.SH HISTORY
+4.4BSD.
+.SH BUGS
+.BR SLIST_FOREACH ()
+doesn't allow
+.I var
+to be removed or freed within the loop,
+as it would interfere with the traversal.
+.BR SLIST_FOREACH_SAFE (),
+which is present on the BSDs but is not present in glibc,
+fixes this limitation by allowing
+.I var
+to safely be removed from the list and freed from within the loop
+without interfering with the traversal.
+.SH EXAMPLES
+.\" SRC BEGIN (slist.c)
+.EX
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/queue.h>
+\&
+struct entry {
+    int data;
+    SLIST_ENTRY(entry) entries;             /* Singly linked list */
+};
+\&
+SLIST_HEAD(slisthead, entry);
+\&
+int
+main(void)
+{
+    struct entry *n1, *n2, *n3, *np;
+    struct slisthead head;                  /* Singly linked list
+                                               head */
+\&
+    SLIST_INIT(&head);                      /* Initialize the queue */
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the head */
+    SLIST_INSERT_HEAD(&head, n1, entries);
+\&
+    n2 = malloc(sizeof(struct entry));      /* Insert after */
+    SLIST_INSERT_AFTER(n1, n2, entries);
+\&
+    SLIST_REMOVE(&head, n2, entry, entries);/* Deletion */
+    free(n2);
+\&
+    n3 = SLIST_FIRST(&head);
+    SLIST_REMOVE_HEAD(&head, entries);      /* Deletion from the head */
+    free(n3);
+\&
+    for (unsigned int i = 0; i < 5; i++) {
+        n1 = malloc(sizeof(struct entry));
+        SLIST_INSERT_HEAD(&head, n1, entries);
+        n1\->data = i;
+    }
+\&
+                                            /* Forward traversal */
+    SLIST_FOREACH(np, &head, entries)
+        printf("%i\en", np\->data);
+\&
+    while (!SLIST_EMPTY(&head)) {           /* List deletion */
+        n1 = SLIST_FIRST(&head);
+        SLIST_REMOVE_HEAD(&head, entries);
+        free(n1);
+    }
+    SLIST_INIT(&head);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR insque (3),
+.BR queue (7)
diff --git a/man/man3/snprintf.3 b/man/man3/snprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/snprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/sockatmark.3 b/man/man3/sockatmark.3
new file mode 100644
index 000000000..6cd2eb6d6
--- /dev/null
+++ b/man/man3/sockatmark.3
@@ -0,0 +1,138 @@
+'\" t
+.\" Copyright (c) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sockatmark 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sockatmark \- determine whether socket is at out-of-band mark
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.BI "int sockatmark(int " sockfd );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sockatmark ():
+.nf
+    _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+.BR sockatmark ()
+returns a value indicating whether or not the socket referred
+to by the file descriptor
+.I sockfd
+is at the out-of-band mark.
+If the socket is at the mark, then 1 is returned;
+if the socket is not at the mark, 0 is returned.
+This function does not remove the out-of-band mark.
+.SH RETURN VALUE
+A successful call to
+.BR sockatmark ()
+returns 1 if the socket is at the out-of-band mark, or 0 if it is not.
+On error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I sockfd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+.\" POSIX.1 says ENOTTY for this case
+.I sockfd
+is not a file descriptor to which
+.BR sockatmark ()
+can be applied.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sockatmark ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.2.4.
+POSIX.1-2001.
+.SH NOTES
+If
+.BR sockatmark ()
+returns 1, then the out-of-band data can be read using the
+.B MSG_OOB
+flag of
+.BR recv (2).
+.P
+Out-of-band data is supported only on some stream socket protocols.
+.P
+.BR sockatmark ()
+can safely be called from a handler for the
+.B SIGURG
+signal.
+.P
+.BR sockatmark ()
+is implemented using the
+.B SIOCATMARK
+.BR ioctl (2)
+operation.
+.SH BUGS
+Prior to glibc 2.4,
+.BR sockatmark ()
+did not work.
+.SH EXAMPLES
+The following code can be used after receipt of a
+.B SIGURG
+signal to read (and discard) all data up to the mark,
+and then read the byte of data at the mark:
+.P
+.EX
+    char buf[BUF_LEN];
+    char oobdata;
+    int atmark, s;
+\&
+    for (;;) {
+        atmark = sockatmark(sockfd);
+        if (atmark == \-1) {
+            perror("sockatmark");
+            break;
+        }
+\&
+        if (atmark)
+            break;
+\&
+        s = read(sockfd, buf, BUF_LEN);
+        if (s == \-1)
+            perror("read");
+        if (s <= 0)
+            break;
+    }
+\&
+    if (atmark == 1) {
+        if (recv(sockfd, &oobdata, 1, MSG_OOB) == \-1) {
+            perror("recv");
+            ...
+        }
+    }
+.EE
+.SH SEE ALSO
+.BR fcntl (2),
+.BR recv (2),
+.BR send (2),
+.BR tcp (7)
diff --git a/man/man3/sprintf.3 b/man/man3/sprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/sprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/sqrt.3 b/man/man3/sqrt.3
new file mode 100644
index 000000000..7a4787810
--- /dev/null
+++ b/man/man3/sqrt.3
@@ -0,0 +1,109 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.TH sqrt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sqrt, sqrtf, sqrtl \- square root function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double sqrt(double " x );
+.BI "float sqrtf(float " x );
+.BI "long double sqrtl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sqrtf (),
+.BR sqrtl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the nonnegative square root of
+.IR x .
+.SH RETURN VALUE
+On success, these functions return the square root of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0), +0 (\-0) is returned.
+.P
+If
+.I x
+is positive infinity, positive infinity is returned.
+.P
+If
+.I x
+is less than \-0,
+a domain error occurs,
+and a NaN is returned.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP less than \-0
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sqrt (),
+.BR sqrtf (),
+.BR sqrtl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR cbrt (3),
+.BR csqrt (3),
+.BR hypot (3)
diff --git a/man/man3/sqrtf.3 b/man/man3/sqrtf.3
new file mode 100644
index 000000000..81258bbc0
--- /dev/null
+++ b/man/man3/sqrtf.3
@@ -0,0 +1 @@
+.so man3/sqrt.3
diff --git a/man/man3/sqrtl.3 b/man/man3/sqrtl.3
new file mode 100644
index 000000000..81258bbc0
--- /dev/null
+++ b/man/man3/sqrtl.3
@@ -0,0 +1 @@
+.so man3/sqrt.3
diff --git a/man/man3/srand.3 b/man/man3/srand.3
new file mode 100644
index 000000000..b007c2fc2
--- /dev/null
+++ b/man/man3/srand.3
@@ -0,0 +1 @@
+.so man3/rand.3
diff --git a/man/man3/srand48.3 b/man/man3/srand48.3
new file mode 100644
index 000000000..3133f7d62
--- /dev/null
+++ b/man/man3/srand48.3
@@ -0,0 +1 @@
+.so man3/drand48.3
diff --git a/man/man3/srand48_r.3 b/man/man3/srand48_r.3
new file mode 100644
index 000000000..81e9d8ef7
--- /dev/null
+++ b/man/man3/srand48_r.3
@@ -0,0 +1 @@
+.so man3/drand48_r.3
diff --git a/man/man3/srandom.3 b/man/man3/srandom.3
new file mode 100644
index 000000000..6e34104e2
--- /dev/null
+++ b/man/man3/srandom.3
@@ -0,0 +1 @@
+.so man3/random.3
diff --git a/man/man3/srandom_r.3 b/man/man3/srandom_r.3
new file mode 100644
index 000000000..b01937f4d
--- /dev/null
+++ b/man/man3/srandom_r.3
@@ -0,0 +1 @@
+.so man3/random_r.3
diff --git a/man/man3/sscanf.3 b/man/man3/sscanf.3
new file mode 100644
index 000000000..d488cd861
--- /dev/null
+++ b/man/man3/sscanf.3
@@ -0,0 +1,730 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)scanf.3	6.14 (Berkeley) 1/8/93
+.\"
+.\" Converted for Linux, Mon Nov 29 15:22:01 1993, faith@cs.unc.edu
+.\" modified to resemble the GNU libio setup used in the Linux libc
+.\" used in versions 4.x (x>4) and 5   Helmut.Geyer@iwr.uni-heidelberg.de
+.\" Modified, aeb, 970121
+.\" 2005-07-14, mtk, added description of %n$ form; various text
+.\"	incorporated from the GNU C library documentation ((C) The
+.\"	Free Software Foundation); other parts substantially rewritten.
+.\"
+.\" 2008-06-23, mtk
+.\"     Add ERRORS section.
+.\"     Document the 'a' and 'm' modifiers for dynamic string allocation.
+.\"
+.TH sscanf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sscanf, vsscanf \- input string format conversion
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int sscanf(const char *restrict " str ,
+.BI "           const char *restrict " format ", ...);"
+.P
+.B #include <stdarg.h>
+.P
+.BI "int vsscanf(const char *restrict " str ,
+.BI "           const char *restrict " format ", va_list " ap );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR vsscanf ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR sscanf ()
+family of functions scans formatted input according to
+.I format
+as described below.
+This format may contain
+.IR "conversion specifications" ;
+the results from such conversions, if any,
+are stored in the locations pointed to by the
+.I pointer
+arguments that follow
+.IR format .
+Each
+.I pointer
+argument must be of a type that is appropriate for the value returned
+by the corresponding conversion specification.
+.P
+If the number of conversion specifications in
+.I format
+exceeds the number of
+.I pointer
+arguments, the results are undefined.
+If the number of
+.I pointer
+arguments exceeds the number of conversion specifications, then the excess
+.I pointer
+arguments are evaluated, but are otherwise ignored.
+.P
+.BR sscanf ()
+These functions
+read their input from the string pointed to by
+.IR str .
+.P
+The
+.BR vsscanf ()
+function is analogous to
+.BR vsprintf (3).
+.P
+The
+.I format
+string consists of a sequence of
+.I directives
+which describe how to process the sequence of input characters.
+If processing of a directive fails, no further input is read, and
+.BR sscanf ()
+returns.
+A "failure" can be either of the following:
+.IR "input failure" ,
+meaning that input characters were unavailable, or
+.IR "matching failure" ,
+meaning that the input was inappropriate (see below).
+.P
+A directive is one of the following:
+.TP
+\[bu]
+A sequence of white-space characters (space, tab, newline, etc.; see
+.BR isspace (3)).
+This directive matches any amount of white space,
+including none, in the input.
+.TP
+\[bu]
+An ordinary character (i.e., one other than white space or \[aq]%\[aq]).
+This character must exactly match the next character of input.
+.TP
+\[bu]
+A conversion specification,
+which commences with a \[aq]%\[aq] (percent) character.
+A sequence of characters from the input is converted according to
+this specification, and the result is placed in the corresponding
+.I pointer
+argument.
+If the next item of input does not match the conversion specification,
+the conversion fails\[em]this is a
+.IR "matching failure" .
+.P
+Each
+.I conversion specification
+in
+.I format
+begins with either the character \[aq]%\[aq] or the character sequence
+"\fB%\fP\fIn\fP\fB$\fP"
+(see below for the distinction) followed by:
+.TP
+\[bu]
+An optional \[aq]*\[aq] assignment-suppression character:
+.BR sscanf ()
+reads input as directed by the conversion specification,
+but discards the input.
+No corresponding
+.I pointer
+argument is required, and this specification is not
+included in the count of successful assignments returned by
+.BR scanf ().
+.TP
+\[bu]
+For decimal conversions, an optional quote character (\[aq]).
+This specifies that the input number may include thousands'
+separators as defined by the
+.B LC_NUMERIC
+category of the current locale.
+(See
+.BR setlocale (3).)
+The quote character may precede or follow the \[aq]*\[aq]
+assignment-suppression character.
+.TP
+\[bu]
+An optional \[aq]m\[aq] character.
+This is used with string conversions
+.RI ( %s ,
+.IR %c ,
+.IR %[ ),
+and relieves the caller of the
+need to allocate a corresponding buffer to hold the input: instead,
+.BR sscanf ()
+allocates a buffer of sufficient size,
+and assigns the address of this buffer to the corresponding
+.I pointer
+argument, which should be a pointer to a
+.I "char\ *"
+variable (this variable does not need to be initialized before the call).
+The caller should subsequently
+.BR free (3)
+this buffer when it is no longer required.
+.TP
+\[bu]
+An optional decimal integer which specifies the
+.IR "maximum field width" .
+Reading of characters stops either when this maximum is reached or
+when a nonmatching character is found, whichever happens first.
+Most conversions discard initial white space characters (the exceptions
+are noted below),
+and these discarded characters don't count toward the maximum field width.
+String input conversions store a terminating null byte (\[aq]\e0\[aq])
+to mark the end of the input;
+the maximum field width does not include this terminator.
+.TP
+\[bu]
+An optional
+.IR "type modifier character" .
+For example, the
+.B l
+type modifier is used with integer conversions such as
+.B %d
+to specify that the corresponding
+.I pointer
+argument refers to a
+.I "long"
+rather than a pointer to an
+.IR int .
+.TP
+\[bu]
+A
+.I "conversion specifier"
+that specifies the type of input conversion to be performed.
+.P
+The conversion specifications in
+.I format
+are of two forms, either beginning with \[aq]%\[aq] or beginning with
+"\fB%\fP\fIn\fP\fB$\fP".
+The two forms should not be mixed in the same
+.I format
+string, except that a string containing
+"\fB%\fP\fIn\fP\fB$\fP"
+specifications can include
+.B %%
+and
+.BR %* .
+If
+.I format
+contains \[aq]%\[aq]
+specifications, then these correspond in order with successive
+.I pointer
+arguments.
+In the
+"\fB%\fP\fIn\fP\fB$\fP"
+form (which is specified in POSIX.1-2001, but not C99),
+.I n
+is a decimal integer that specifies that the converted input should
+be placed in the location referred to by the
+.IR n -th
+.I pointer
+argument following
+.IR format .
+.SS Conversions
+The following
+.I "type modifier characters"
+can appear in a conversion specification:
+.TP
+.B h
+Indicates that the conversion will be one of
+\fBd\fP, \fBi\fP, \fBo\fP, \fBu\fP, \fBx\fP, \fBX\fP, or \fBn\fP
+and the next pointer is a pointer to a
+.I short
+or
+.I unsigned short
+(rather than
+.IR int ).
+.TP
+.B hh
+As for
+.BR h ,
+but the next pointer is a pointer to a
+.I signed char
+or
+.IR "unsigned char" .
+.TP
+.B j
+As for
+.BR h ,
+but the next pointer is a pointer to an
+.I intmax_t
+or a
+.IR uintmax_t .
+This modifier was introduced in C99.
+.TP
+.B l
+Indicates either that the conversion will be one of
+\fBd\fP, \fBi\fP, \fBo\fP, \fBu\fP, \fBx\fP, \fBX\fP, or \fBn\fP
+and the next pointer is a pointer to a
+.I long
+or
+.I unsigned long
+(rather than
+.IR int ),
+or that the conversion will be one of
+\fBe\fP, \fBf\fP, or \fBg\fP
+and the next pointer is a pointer to
+.I double
+(rather than
+.IR float ).
+If used with
+.B %c
+or
+.BR %s ,
+the corresponding parameter is considered
+as a pointer to a wide character or wide-character string respectively.
+.\" This use of l was introduced in Amendment 1 to ISO C90.
+.TP
+.B ll
+(ell-ell)
+Indicates that the conversion will be one of
+.BR b ,
+.BR d ,
+.BR i ,
+.BR o ,
+.BR u ,
+.BR x ,
+.BR X ,
+or
+.B n
+and the next pointer is a pointer to a
+.I long long
+or
+.I unsigned long long
+(rather than
+.IR int ).
+.TP
+.B L
+Indicates that the conversion will be either
+\fBe\fP, \fBf\fP, or \fBg\fP
+and the next pointer is a pointer to
+.I "long double"
+or
+(as a GNU extension)
+the conversion will be
+\fBd\fP, \fBi\fP, \fBo\fP, \fBu\fP, or \fBx\fP
+and the next pointer is a pointer to
+.IR "long long" .
+.\" MTK, Jul 05: The following is no longer true for modern
+.\" ANSI C (i.e., C99):
+.\" (Note that long long is not an
+.\" ANSI C
+.\" type. Any program using this will not be portable to all
+.\" architectures).
+.TP
+.B q
+equivalent to
+.BR L .
+This specifier does not exist in ANSI C.
+.TP
+.B t
+As for
+.BR h ,
+but the next pointer is a pointer to a
+.IR ptrdiff_t .
+This modifier was introduced in C99.
+.TP
+.B z
+As for
+.BR h ,
+but the next pointer is a pointer to a
+.IR size_t .
+This modifier was introduced in C99.
+.P
+The following
+.I "conversion specifiers"
+are available:
+.TP
+.B %
+Matches a literal \[aq]%\[aq].
+That is,
+.B %\&%
+in the format string matches a
+single input \[aq]%\[aq] character.
+No conversion is done (but initial white space characters are discarded),
+and assignment does not occur.
+.TP
+.B d
+Matches an optionally signed decimal integer;
+the next pointer must be a pointer to
+.IR int .
+.\" .TP
+.\" .B D
+.\" Equivalent to
+.\" .IR ld ;
+.\" this exists only for backward compatibility.
+.\" (Note: thus only in libc4
+.\" In libc5 and glibc the
+.\" .B %D
+.\" is silently ignored, causing old programs to fail mysteriously.)
+.TP
+.B i
+Matches an optionally signed integer; the next pointer must be a pointer to
+.IR int .
+The integer is read in base 16 if it begins with
+.I 0x
+or
+.IR 0X ,
+in base 8 if it begins with
+.IR 0 ,
+and in base 10 otherwise.
+Only characters that correspond to the base are used.
+.TP
+.B o
+Matches an unsigned octal integer; the next pointer must be a pointer to
+.IR "unsigned int" .
+.TP
+.B u
+Matches an unsigned decimal integer; the next pointer must be a
+pointer to
+.IR "unsigned int" .
+.TP
+.B x
+Matches an unsigned hexadecimal integer
+(that may optionally begin with a prefix of
+.I 0x
+or
+.IR 0X ,
+which is discarded); the next pointer must
+be a pointer to
+.IR "unsigned int" .
+.TP
+.B X
+Equivalent to
+.BR x .
+.TP
+.B f
+Matches an optionally signed floating-point number; the next pointer must
+be a pointer to
+.IR float .
+.TP
+.B e
+Equivalent to
+.BR f .
+.TP
+.B g
+Equivalent to
+.BR f .
+.TP
+.B E
+Equivalent to
+.BR f .
+.TP
+.B a
+(C99) Equivalent to
+.BR f .
+.TP
+.B s
+Matches a sequence of non-white-space characters;
+the next pointer must be a pointer to the initial element of a
+character array that is long enough to hold the input sequence and
+the terminating null byte (\[aq]\e0\[aq]), which is added automatically.
+The input string stops at white space or at the maximum field
+width, whichever occurs first.
+.TP
+.B c
+Matches a sequence of characters whose length is specified by the
+.I maximum field width
+(default 1); the next pointer must be a pointer to
+.IR char ,
+and there must be enough room for all the characters
+(no terminating null byte is added).
+The usual skip of leading white space is suppressed.
+To skip white space first, use an explicit space in the format.
+.TP
+.B \&[
+Matches a nonempty sequence of characters from the specified set of
+accepted characters; the next pointer must be a pointer to
+.IR char ,
+and there must be enough room for all the characters in the string, plus a
+terminating null byte.
+The usual skip of leading white space is suppressed.
+The string is to be made up of characters in (or not in) a particular set;
+the set is defined by the characters between the open bracket
+.B [
+character and a close bracket
+.B ]
+character.
+The set
+.I excludes
+those characters if the first character after the open bracket is a
+circumflex
+.RB ( \[ha] ).
+To include a close bracket in the set, make it the first character after
+the open bracket or the circumflex; any other position will end the set.
+The hyphen character
+.B \-
+is also special; when placed between two other characters, it adds all
+intervening characters to the set.
+To include a hyphen, make it the last
+character before the final close bracket.
+For instance,
+.B [\[ha]]0\-9\-]
+means
+the set "everything except close bracket, zero through nine, and hyphen".
+The string ends with the appearance of a character not in the (or, with a
+circumflex, in) set or when the field width runs out.
+.TP
+.B p
+Matches a pointer value (as printed by
+.B %p
+in
+.BR printf (3));
+the next pointer must be a pointer to a pointer to
+.IR void .
+.TP
+.B n
+Nothing is expected; instead, the number of characters consumed thus far
+from the input is stored through the next pointer, which must be a pointer
+to
+.IR int ,
+or variant whose size matches the (optionally)
+supplied integer length modifier.
+This is
+.I not
+a conversion and does
+.I not
+increase the count returned by the function.
+The assignment can be suppressed with the
+.B *
+assignment-suppression character, but the effect on the
+return value is undefined.
+Therefore
+.B %*n
+conversions should not be used.
+.SH RETURN VALUE
+On success, these functions return the number of input items
+successfully matched and assigned;
+this can be fewer than provided for,
+or even zero, in the event of an early matching failure.
+.P
+The value
+.B EOF
+is returned if the end of input is reached before either the first
+successful conversion or a matching failure occurs.
+.SH ERRORS
+.TP
+.B EILSEQ
+Input byte sequence does not form a valid character.
+.TP
+.B EINVAL
+Not enough arguments; or
+.I format
+is NULL.
+.TP
+.B ENOMEM
+Out of memory.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sscanf (),
+.BR vsscanf ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.P
+The
+.B q
+specifier is the 4.4BSD notation for
+.IR "long long" ,
+while
+.B ll
+or the usage of
+.B L
+in integer conversions is the GNU notation.
+.P
+The Linux version of these functions is based on the
+.I GNU
+.I libio
+library.
+Take a look at the
+.I info
+documentation of
+.I GNU
+.I libc (glibc-1.08)
+for a more concise description.
+.SH NOTES
+.SS The 'a' assignment-allocation modifier
+Originally, the GNU C library supported dynamic allocation for string inputs
+(as a nonstandard extension) via the
+.B a
+character.
+(This feature is present at least as far back as glibc 2.0.)
+Thus, one could write the following to have
+.BR sscanf ()
+allocate a buffer for a string,
+with a pointer to that buffer being returned in
+.IR *buf :
+.P
+.in +4n
+.EX
+char *buf;
+sscanf(str, "%as", &buf);
+.EE
+.in
+.P
+The use of the letter
+.B a
+for this purpose was problematic, since
+.B a
+is also specified by the ISO C standard as a synonym for
+.B f
+(floating-point input).
+POSIX.1-2008 instead specifies the
+.B m
+modifier for assignment allocation (as documented in DESCRIPTION, above).
+.P
+Note that the
+.B a
+modifier is not available if the program is compiled with
+.I gcc\~\-std=c99
+or
+.I gcc\~\-D_ISOC99_SOURCE
+(unless
+.B _GNU_SOURCE
+is also specified), in which case the
+.B a
+is interpreted as a specifier for floating-point numbers (see above).
+.P
+Support for the
+.B m
+modifier was added to glibc 2.7,
+and new programs should use that modifier instead of
+.BR a .
+.P
+As well as being standardized by POSIX, the
+.B m
+modifier has the following further advantages over
+the use of
+.BR a :
+.IP \[bu] 3
+It may also be applied to
+.B %c
+conversion specifiers (e.g.,
+.BR %3mc ).
+.IP \[bu]
+It avoids ambiguity with respect to the
+.B %a
+floating-point conversion specifier (and is unaffected by
+.I gcc\~\-std=c99
+etc.).
+.SH BUGS
+.SS Numeric conversion specifiers
+Use of the numeric conversion specifiers produces Undefined Behavior
+for invalid input.
+See
+.UR https://port70.net/\:%7Ensz/\:c/\:c11/\:n1570.html\:#7.21.6.2p10
+C11 7.21.6.2/10
+.UE .
+This is a bug in the ISO C standard,
+and not an inherent design issue with the API.
+However,
+current implementations are not safe from that bug,
+so it is not recommended to use them.
+Instead,
+programs should use functions such as
+.BR strtol (3)
+to parse numeric input.
+Alternatively,
+mitigate it by specifying a maximum field width.
+.SS Nonstandard modifiers
+These functions are fully C99 conformant, but provide the
+additional modifiers
+.B q
+and
+.B a
+as well as an additional behavior of the
+.B L
+and
+.B ll
+modifiers.
+The latter may be considered to be a bug, as it changes the
+behavior of modifiers defined in C99.
+.P
+Some combinations of the type modifiers and conversion
+specifiers defined by C99 do not make sense
+(e.g.,
+.BR "%Ld" ).
+While they may have a well-defined behavior on Linux, this need not
+to be so on other architectures.
+Therefore it usually is better to use
+modifiers that are not defined by C99 at all, that is, use
+.B q
+instead of
+.B L
+in combination with
+\fBd\fP, \fBi\fP, \fBo\fP, \fBu\fP, \fBx\fP, and \fBX\fP
+conversions or
+.BR ll .
+.P
+The usage of
+.B q
+is not the same as on 4.4BSD,
+as it may be used in float conversions equivalently to
+.BR L .
+.SH EXAMPLES
+To use the dynamic allocation conversion specifier, specify
+.B m
+as a length modifier (thus
+.B %ms
+or
+\fB%m[\fP\fIrange\fP\fB]\fP).
+The caller must
+.BR free (3)
+the returned string, as in the following example:
+.P
+.in +4n
+.EX
+char *p;
+int n;
+\&
+errno = 0;
+n = sscanf(str, "%m[a\-z]", &p);
+if (n == 1) {
+    printf("read: %s\en", p);
+    free(p);
+} else if (errno != 0) {
+    perror("sscanf");
+} else {
+    fprintf(stderr, "No matching characters\en");
+}
+.EE
+.in
+.P
+As shown in the above example, it is necessary to call
+.BR free (3)
+only if the
+.BR sscanf ()
+call successfully read a string.
+.SH SEE ALSO
+.BR getc (3),
+.BR printf (3),
+.BR setlocale (3),
+.BR strtod (3),
+.BR strtol (3),
+.BR strtoul (3)
diff --git a/man/man3/ssignal.3 b/man/man3/ssignal.3
new file mode 100644
index 000000000..047cab287
--- /dev/null
+++ b/man/man3/ssignal.3
@@ -0,0 +1 @@
+.so man3/gsignal.3
diff --git a/man/man3/stailq.3 b/man/man3/stailq.3
new file mode 100644
index 000000000..eca802cbd
--- /dev/null
+++ b/man/man3/stailq.3
@@ -0,0 +1,377 @@
+.\" Copyright (c) 1993
+.\"    The Regents of the University of California.  All rights reserved.
+.\" and Copyright (c) 2020 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"
+.TH STAILQ 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+.\"SIMPLEQ_CONCAT,
+SIMPLEQ_EMPTY,
+SIMPLEQ_ENTRY,
+SIMPLEQ_FIRST,
+SIMPLEQ_FOREACH,
+.\"SIMPLEQ_FOREACH_FROM,
+.\"SIMPLEQ_FOREACH_FROM_SAFE,
+.\"SIMPLEQ_FOREACH_SAFE,
+SIMPLEQ_HEAD,
+SIMPLEQ_HEAD_INITIALIZER,
+SIMPLEQ_INIT,
+SIMPLEQ_INSERT_AFTER,
+SIMPLEQ_INSERT_HEAD,
+SIMPLEQ_INSERT_TAIL,
+.\"SIMPLEQ_LAST,
+SIMPLEQ_NEXT,
+SIMPLEQ_REMOVE,
+.\"SIMPLEQ_REMOVE_AFTER,
+SIMPLEQ_REMOVE_HEAD,
+.\"SIMPLEQ_SWAP,
+STAILQ_CONCAT,
+STAILQ_EMPTY,
+STAILQ_ENTRY,
+STAILQ_FIRST,
+STAILQ_FOREACH,
+.\"STAILQ_FOREACH_FROM,
+.\"STAILQ_FOREACH_FROM_SAFE,
+.\"STAILQ_FOREACH_SAFE,
+STAILQ_HEAD,
+STAILQ_HEAD_INITIALIZER,
+STAILQ_INIT,
+STAILQ_INSERT_AFTER,
+STAILQ_INSERT_HEAD,
+STAILQ_INSERT_TAIL,
+.\"STAILQ_LAST,
+STAILQ_NEXT,
+STAILQ_REMOVE,
+.\"STAILQ_REMOVE_AFTER,
+STAILQ_REMOVE_HEAD,
+.\"STAILQ_SWAP
+\- implementation of a singly linked tail queue
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/queue.h>
+.P
+.B STAILQ_ENTRY(TYPE);
+.P
+.B STAILQ_HEAD(HEADNAME, TYPE);
+.BI "STAILQ_HEAD STAILQ_HEAD_INITIALIZER(STAILQ_HEAD " head );
+.BI "void STAILQ_INIT(STAILQ_HEAD *" head );
+.P
+.BI "int STAILQ_EMPTY(STAILQ_HEAD *" head );
+.P
+.BI "void STAILQ_INSERT_HEAD(STAILQ_HEAD *" head ,
+.BI "                         struct TYPE *" elm ", STAILQ_ENTRY " NAME );
+.BI "void STAILQ_INSERT_TAIL(STAILQ_HEAD *" head ,
+.BI "                         struct TYPE *" elm ", STAILQ_ENTRY " NAME );
+.BI "void STAILQ_INSERT_AFTER(STAILQ_HEAD *" head ", struct TYPE *" listelm ,
+.BI "                         struct TYPE *" elm ", STAILQ_ENTRY " NAME );
+.P
+.BI "struct TYPE *STAILQ_FIRST(STAILQ_HEAD *" head );
+.\" .BI "struct TYPE *STAILQ_LAST(STAILQ_HEAD *" head ", struct TYPE *" elm ,
+.\" .BI "                          STAILQ_ENTRY " NAME );
+.BI "struct TYPE *STAILQ_NEXT(struct TYPE *" elm ", STAILQ_ENTRY " NAME );
+.P
+.BI "STAILQ_FOREACH(struct TYPE *" var ", STAILQ_HEAD *" head ", STAILQ_ENTRY " NAME );
+.\" .BI "STAILQ_FOREACH_FROM(struct TYPE *" var ", STAILQ_HEAD *" head ,
+.\" .BI "                          STAILQ_ENTRY " NAME );
+.\" .P
+.\" .BI "STAILQ_FOREACH_SAFE(struct TYPE *" var ", STAILQ_HEAD *" head ,
+.\" .BI "                          STAILQ_ENTRY " NAME ", struct TYPE *" temp_var );
+.\" .BI "STAILQ_FOREACH_FROM_SAFE(struct TYPE *" var ", STAILQ_HEAD *" head ,
+.\" .BI "                          STAILQ_ENTRY " NAME ", struct TYPE *" temp_var );
+.P
+.BI "void STAILQ_REMOVE(STAILQ_HEAD *" head ", struct TYPE *" elm ", TYPE,"
+.BI "                         STAILQ_ENTRY " NAME );
+.BI "void STAILQ_REMOVE_HEAD(STAILQ_HEAD *" head ,
+.BI "                         STAILQ_ENTRY " NAME );
+.\" .BI "void STAILQ_REMOVE_AFTER(STAILQ_HEAD *" head ", struct TYPE *" elm ,
+.\" .BI "                          STAILQ_ENTRY " NAME );
+.P
+.BI "void STAILQ_CONCAT(STAILQ_HEAD *" head1 ", STAILQ_HEAD *" head2 );
+.\" .BI "void STAILQ_SWAP(STAILQ_HEAD *" head1 ", STAILQ_HEAD *" head2 ,
+.\" .BI "                          STAILQ_ENTRY " NAME );
+.fi
+.IR Note :
+Identical macros prefixed with SIMPLEQ instead of STAILQ exist; see NOTES.
+.SH DESCRIPTION
+These macros define and operate on singly linked tail queues.
+.P
+In the macro definitions,
+.I TYPE
+is the name of a user-defined structure,
+that must contain a field of type
+.IR STAILQ_ENTRY ,
+named
+.IR NAME .
+The argument
+.I HEADNAME
+is the name of a user-defined structure that must be declared
+using the macro
+.BR STAILQ_HEAD ().
+.SS Creation
+A singly linked tail queue is headed by a structure defined by the
+.BR STAILQ_HEAD ()
+macro.
+This structure contains a pair of pointers,
+one to the first element in the tail queue and the other to
+the last element in the tail queue.
+The elements are singly linked for minimum space and pointer
+manipulation overhead at the expense of O(n) removal for arbitrary elements.
+New elements can be added to the tail queue after an existing element,
+at the head of the tail queue, or at the end of the tail queue.
+A
+.I STAILQ_HEAD
+structure is declared as follows:
+.P
+.in +4
+.EX
+STAILQ_HEAD(HEADNAME, TYPE) head;
+.EE
+.in
+.P
+where
+.I struct HEADNAME
+is the structure to be defined, and
+.I struct TYPE
+is the type of the elements to be linked into the tail queue.
+A pointer to the head of the tail queue can later be declared as:
+.P
+.in +4
+.EX
+struct HEADNAME *headp;
+.EE
+.in
+.P
+(The names
+.I head
+and
+.I headp
+are user selectable.)
+.P
+.BR STAILQ_ENTRY ()
+declares a structure that connects the elements in the tail queue.
+.P
+.BR STAILQ_HEAD_INITIALIZER ()
+evaluates to an initializer for the tail queue
+.IR head .
+.P
+.BR STAILQ_INIT ()
+initializes the tail queue referenced by
+.IR head .
+.P
+.BR STAILQ_EMPTY ()
+evaluates to true if there are no items on the tail queue.
+.SS Insertion
+.BR STAILQ_INSERT_HEAD ()
+inserts the new element
+.I elm
+at the head of the tail queue.
+.P
+.BR STAILQ_INSERT_TAIL ()
+inserts the new element
+.I elm
+at the end of the tail queue.
+.P
+.BR STAILQ_INSERT_AFTER ()
+inserts the new element
+.I elm
+after the element
+.IR listelm .
+.SS Traversal
+.BR STAILQ_FIRST ()
+returns the first item on the tail queue or NULL if the tail queue is empty.
+.\" .P
+.\" .BR STAILQ_LAST ()
+.\" returns the last item on the tail queue.
+.\" If the tail queue is empty the return value is NULL .
+.P
+.BR STAILQ_NEXT ()
+returns the next item on the tail queue, or NULL this item is the last.
+.P
+.BR STAILQ_FOREACH ()
+traverses the tail queue referenced by
+.I head
+in the forward direction,
+assigning each element in turn to
+.IR var .
+.\" .P
+.\" .BR STAILQ_FOREACH_FROM ()
+.\" behaves identically to
+.\" .BR STAILQ_FOREACH ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found STAILQ element and begins the loop at
+.\" .I var
+.\" instead of the first element in the STAILQ referenced by
+.\" .IR head .
+.\" .P
+.\" .BR STAILQ_FOREACH_SAFE ()
+.\" traverses the tail queue referenced by
+.\" .I head
+.\" in the forward direction, assigning each element
+.\" in turn to
+.\" .IR var .
+.\" However, unlike
+.\" .BR STAILQ_FOREACH ()
+.\" here it is permitted to both remove
+.\" .I var
+.\" as well as free it from within the loop safely without interfering with the
+.\" traversal.
+.\" .P
+.\" .BR STAILQ_FOREACH_FROM_SAFE ()
+.\" behaves identically to
+.\" .BR STAILQ_FOREACH_SAFE ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found STAILQ element and begins the loop at
+.\" .I var
+.\" instead of the first element in the STAILQ referenced by
+.\" .IR head .
+.SS Removal
+.BR STAILQ_REMOVE ()
+removes the element
+.I elm
+from the tail queue.
+.P
+.BR STAILQ_REMOVE_HEAD ()
+removes the element at the head of the tail queue.
+For optimum efficiency,
+elements being removed from the head of the tail queue should
+use this macro explicitly rather than the generic
+.BR STAILQ_REMOVE ()
+macro.
+.\" .P
+.\" .BR STAILQ_REMOVE_AFTER ()
+.\" removes the element after
+.\" .I elm
+.\" from the tail queue.
+.\" Unlike
+.\" .BR STAILQ_REMOVE (),
+.\" this macro does not traverse the entire tail queue.
+.SS Other features
+.BR STAILQ_CONCAT ()
+concatenates the tail queue headed by
+.I head2
+onto the end of the one headed by
+.I head1
+removing all entries from the former.
+.\" .P
+.\" .BR STAILQ_SWAP ()
+.\" swaps the contents of
+.\" .I head1
+.\" and
+.\" .IR head2 .
+.SH RETURN VALUE
+.BR STAILQ_EMPTY ()
+returns nonzero if the queue is empty,
+and zero if the queue contains at least one entry.
+.P
+.BR STAILQ_FIRST (),
+and
+.BR STAILQ_NEXT ()
+return a pointer to the first or next
+.I TYPE
+structure, respectively.
+.P
+.BR STAILQ_HEAD_INITIALIZER ()
+returns an initializer that can be assigned to the queue
+.IR head .
+.SH VERSIONS
+Some BSDs provide SIMPLEQ instead of STAILQ.
+They are identical, but for historical reasons
+they were named differently on different BSDs.
+STAILQ originated on FreeBSD, and SIMPLEQ originated on NetBSD.
+For compatibility reasons, some systems provide both sets of macros.
+glibc provides both STAILQ and SIMPLEQ,
+which are identical except for a missing SIMPLEQ equivalent to
+.BR STAILQ_CONCAT ().
+.SH BUGS
+.BR STAILQ_FOREACH ()
+doesn't allow
+.I var
+to be removed or freed within the loop,
+as it would interfere with the traversal.
+.BR STAILQ_FOREACH_SAFE (),
+which is present on the BSDs but is not present in glibc,
+fixes this limitation by allowing
+.I var
+to safely be removed from the list and freed from within the loop
+without interfering with the traversal.
+.SH STANDARDS
+BSD.
+.SH HISTORY
+4.4BSD.
+.SH EXAMPLES
+.\" SRC BEGIN (stailq.c)
+.EX
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/queue.h>
+\&
+struct entry {
+    int data;
+    STAILQ_ENTRY(entry) entries;        /* Singly linked tail queue */
+};
+\&
+STAILQ_HEAD(stailhead, entry);
+\&
+int
+main(void)
+{
+    struct entry *n1, *n2, *n3, *np;
+    struct stailhead head;                  /* Singly linked tail queue
+                                               head */
+\&
+    STAILQ_INIT(&head);                     /* Initialize the queue */
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the head */
+    STAILQ_INSERT_HEAD(&head, n1, entries);
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the tail */
+    STAILQ_INSERT_TAIL(&head, n1, entries);
+\&
+    n2 = malloc(sizeof(struct entry));      /* Insert after */
+    STAILQ_INSERT_AFTER(&head, n1, n2, entries);
+\&
+    STAILQ_REMOVE(&head, n2, entry, entries); /* Deletion */
+    free(n2);
+\&
+    n3 = STAILQ_FIRST(&head);
+    STAILQ_REMOVE_HEAD(&head, entries);     /* Deletion from the head */
+    free(n3);
+\&
+    n1 = STAILQ_FIRST(&head);
+    n1\->data = 0;
+    for (unsigned int i = 1; i < 5; i++) {
+        n1 = malloc(sizeof(struct entry));
+        STAILQ_INSERT_HEAD(&head, n1, entries);
+        n1\->data = i;
+    }
+                                            /* Forward traversal */
+    STAILQ_FOREACH(np, &head, entries)
+        printf("%i\en", np\->data);
+                                            /* TailQ deletion */
+    n1 = STAILQ_FIRST(&head);
+    while (n1 != NULL) {
+        n2 = STAILQ_NEXT(n1, entries);
+        free(n1);
+        n1 = n2;
+    }
+    STAILQ_INIT(&head);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR insque (3),
+.BR queue (7)
diff --git a/man/man3/static_assert.3 b/man/man3/static_assert.3
new file mode 100644
index 000000000..04b24a95a
--- /dev/null
+++ b/man/man3/static_assert.3
@@ -0,0 +1,119 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH static_assert 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+static_assert, _Static_assert \- fail compilation if assertion is false
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <assert.h>
+.P
+.BI "void static_assert(scalar " constant-expression ", const char *" msg );
+.P
+/* Since C23: */
+.BI "void static_assert(scalar " constant-expression );
+.fi
+.SH DESCRIPTION
+This macro is similar to
+.BR \%assert (3),
+but it works at compile time,
+generating a compilation error (with an optional message)
+when the input is false (i.e., compares equal to zero).
+.P
+If the input is nonzero,
+no code is emitted.
+.P
+.I msg
+must be a string literal.
+Since C23, this argument is optional.
+.P
+There's a keyword,
+.BR \%_Static_assert (),
+that behaves identically,
+and can be used without including
+.IR <assert.h> .
+.SH RETURN VALUE
+No value is returned.
+.SH VERSIONS
+In C11,
+the second argument
+.RI ( msg )
+was mandatory;
+since C23,
+it can be omitted.
+.SH STANDARDS
+C11 and later.
+.SH EXAMPLES
+.BR static_assert ()
+can't be used in some places,
+like for example at global scope.
+For that,
+a macro
+.BR \%must_be ()
+can be written in terms of
+.BR \%static_assert ().
+The following program uses the macro to get the size of an array safely.
+.P
+.in +4n
+.\" SRC BEGIN (must_be.c)
+.EX
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+/*
+ * This macro behaves like static_assert(), failing to
+ * compile if its argument is not true.  However, it always
+ * returns 0, which allows using it everywhere an expression
+ * can be used.
+ */
+#define must_be(e)                                        \e
+(                                                         \e
+    0 * (int) sizeof(                                     \e
+        struct {                                          \e
+            static_assert(e);                             \e
+            int  ISO_C_forbids_a_struct_with_no_members;  \e
+        }                                                 \e
+    )                                                     \e
+)
+\&
+#define is_same_type(a, b)  \e
+    __builtin_types_compatible_p(typeof(a), typeof(b))
+\&
+#define is_array(arr)       (!is_same_type((arr), &*(arr)))
+#define must_be_array(arr)  must_be(is_array(arr))
+\&
+#define sizeof_array(arr)   (sizeof(arr) + must_be_array(arr))
+#define nitems(arr)         (sizeof((arr)) / sizeof((arr)[0]) \e
+                             + must_be_array(arr))
+\&
+int     foo[10];
+int8_t  bar[sizeof_array(foo)];
+\&
+int
+main(void)
+{
+    for (size_t i = 0; i < nitems(foo); i++) {
+        foo[i] = i;
+    }
+\&
+    memcpy(bar, foo, sizeof_array(bar));
+\&
+    for (size_t i = 0; i < nitems(bar); i++) {
+        printf("%d,", bar[i]);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR assert (3)
diff --git a/man/man3/statvfs.3 b/man/man3/statvfs.3
new file mode 100644
index 000000000..c694aeb1f
--- /dev/null
+++ b/man/man3/statvfs.3
@@ -0,0 +1,256 @@
+'\" t
+.\" Copyright (C) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" The pathconf note is from Walter Harms
+.\" This is not a system call on Linux
+.\"
+.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH statvfs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+statvfs, fstatvfs \- get filesystem statistics
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/statvfs.h>
+.P
+.BI "int statvfs(const char *restrict " path \
+", struct statvfs *restrict " buf );
+.BI "int fstatvfs(int " fd ", struct statvfs *" buf );
+.fi
+.SH DESCRIPTION
+The function
+.BR statvfs ()
+returns information about a mounted filesystem.
+.I path
+is the pathname of any file within the mounted filesystem.
+.I buf
+is a pointer to a
+.I statvfs
+structure defined approximately as follows:
+.P
+.in +4n
+.EX
+struct statvfs {
+    unsigned long  f_bsize;    /* Filesystem block size */
+    unsigned long  f_frsize;   /* Fragment size */
+    fsblkcnt_t     f_blocks;   /* Size of fs in f_frsize units */
+    fsblkcnt_t     f_bfree;    /* Number of free blocks */
+    fsblkcnt_t     f_bavail;   /* Number of free blocks for
+                                  unprivileged users */
+    fsfilcnt_t     f_files;    /* Number of inodes */
+    fsfilcnt_t     f_ffree;    /* Number of free inodes */
+    fsfilcnt_t     f_favail;   /* Number of free inodes for
+                                  unprivileged users */
+    unsigned long  f_fsid;     /* Filesystem ID */
+    unsigned long  f_flag;     /* Mount flags */
+    unsigned long  f_namemax;  /* Maximum filename length */
+};
+.EE
+.in
+.P
+Here the types
+.I fsblkcnt_t
+and
+.I fsfilcnt_t
+are defined in
+.IR <sys/types.h> .
+Both used to be
+.IR "unsigned long" .
+.P
+The field
+.I f_flag
+is a bit mask indicating various options that were employed
+when mounting this filesystem.
+It contains zero or more of the following flags:
+.\" XXX Keep this list in sync with statfs(2)
+.TP
+.B ST_MANDLOCK
+Mandatory locking is permitted on the filesystem (see
+.BR fcntl (2)).
+.TP
+.B ST_NOATIME
+Do not update access times; see
+.BR mount (2).
+.TP
+.B ST_NODEV
+Disallow access to device special files on this filesystem.
+.TP
+.B ST_NODIRATIME
+Do not update directory access times; see
+.BR mount (2).
+.TP
+.B ST_NOEXEC
+Execution of programs is disallowed on this filesystem.
+.TP
+.B ST_NOSUID
+The set-user-ID and set-group-ID bits are ignored by
+.BR exec (3)
+for executable files on this filesystem
+.TP
+.B ST_RDONLY
+This filesystem is mounted read-only.
+.TP
+.B ST_RELATIME
+Update atime relative to mtime/ctime; see
+.BR mount (2).
+.TP
+.B ST_SYNCHRONOUS
+Writes are synched to the filesystem immediately (see the description of
+.B O_SYNC
+in
+.BR open (2)).
+.P
+It is unspecified whether all members of the returned struct
+have meaningful values on all filesystems.
+.P
+.BR fstatvfs ()
+returns the same information about an open file referenced by descriptor
+.IR fd .
+.SH RETURN VALUE
+On success, zero is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+.RB ( statvfs ())
+Search permission is denied for a component of the path prefix of
+.IR path .
+(See also
+.BR path_resolution (7).)
+.TP
+.B EBADF
+.RB ( fstatvfs ())
+.I fd
+is not a valid open file descriptor.
+.TP
+.B EFAULT
+.I Buf
+or
+.I path
+points to an invalid address.
+.TP
+.B EINTR
+This call was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EIO
+An I/O error occurred while reading from the filesystem.
+.TP
+.B ELOOP
+.RB ( statvfs ())
+Too many symbolic links were encountered in translating
+.IR path .
+.TP
+.B ENAMETOOLONG
+.RB ( statvfs ())
+.I path
+is too long.
+.TP
+.B ENOENT
+.RB ( statvfs ())
+The file referred to by
+.I path
+does not exist.
+.TP
+.B ENOMEM
+Insufficient kernel memory was available.
+.TP
+.B ENOSYS
+The filesystem does not support this call.
+.TP
+.B ENOTDIR
+.RB ( statvfs ())
+A component of the path prefix of
+.I path
+is not a directory.
+.TP
+.B EOVERFLOW
+Some values were too large to be represented in the returned struct.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR statvfs (),
+.BR fstatvfs ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Only the
+.B ST_NOSUID
+and
+.B ST_RDONLY
+flags of the
+.I f_flag
+field are specified in POSIX.1.
+To obtain definitions of the remaining flags, one must define
+.BR _GNU_SOURCE .
+.SH NOTES
+The Linux kernel has system calls
+.BR statfs (2)
+and
+.BR fstatfs (2)
+to support this library call.
+.P
+The glibc implementations of
+.P
+.in +4n
+.EX
+pathconf(path, _PC_REC_XFER_ALIGN);
+pathconf(path, _PC_ALLOC_SIZE_MIN);
+pathconf(path, _PC_REC_MIN_XFER_SIZE);
+.EE
+.in
+.P
+respectively use the
+.IR f_frsize ,
+.IR f_frsize ,
+and
+.I f_bsize
+fields returned by a call to
+.BR statvfs ()
+with the argument
+.IR path .
+.P
+Under Linux,
+.I f_favail
+is always the same as
+.IR f_ffree ,
+and there's no way for a filesystem to report otherwise.
+This is not an issue,
+since no filesystems with an inode root reservation exist.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Before glibc 2.13,
+.\" glibc commit 3cdaa6adb113a088fdfb87aa6d7747557eccc58d
+.BR statvfs ()
+populated the bits of the
+.I f_flag
+field by scanning the mount options shown in
+.IR /proc/mounts .
+However, starting with Linux 2.6.36, the underlying
+.BR statfs (2)
+system call provides the necessary information via the
+.I f_flags
+field, and since glibc 2.13, the
+.BR statvfs ()
+function will use information from that field rather than scanning
+.IR /proc/mounts .
+.SH SEE ALSO
+.BR statfs (2)
diff --git a/man/man3/stdarg.3 b/man/man3/stdarg.3
new file mode 100644
index 000000000..4168487d0
--- /dev/null
+++ b/man/man3/stdarg.3
@@ -0,0 +1,297 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" the American National Standards Committee X3, on Information
+.\" Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"	@(#)stdarg.3	6.8 (Berkeley) 6/29/91
+.\"
+.\" Converted for Linux, Mon Nov 29 15:11:11 1993, faith@cs.unc.edu
+.\" Additions, 2001-10-14, aeb
+.\"
+.TH stdarg 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stdarg, va_start, va_arg, va_end, va_copy \- variable argument lists
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdarg.h>
+.P
+.BI "void va_start(va_list " ap ", " last );
+.IB type " va_arg(va_list " ap ", " type );
+.BI "void va_end(va_list " ap );
+.BI "void va_copy(va_list " dest ", va_list " src );
+.fi
+.SH DESCRIPTION
+A function may be called with a varying number of arguments of varying
+types.
+The include file
+.I <stdarg.h>
+declares a type
+.I va_list
+and defines three macros for stepping through a list of arguments whose
+number and types are not known to the called function.
+.P
+The called function must declare an object of type
+.I va_list
+which is used by the macros
+.BR va_start (),
+.BR va_arg (),
+and
+.BR va_end ().
+.SS va_start()
+The
+.BR va_start ()
+macro initializes
+.I ap
+for subsequent use by
+.BR va_arg ()
+and
+.BR va_end (),
+and must be called first.
+.P
+The argument
+.I last
+is the name of the last argument before the variable argument list, that is,
+the last argument of which the calling function knows the type.
+.P
+Because the address of this argument may be used in the
+.BR va_start ()
+macro, it should not be declared as a register variable,
+or as a function or an array type.
+.SS va_arg()
+The
+.BR va_arg ()
+macro expands to an expression that has the type and value of the next
+argument in the call.
+The argument
+.I ap
+is the
+.I va_list
+.I ap
+initialized by
+.BR va_start ().
+Each call to
+.BR va_arg ()
+modifies
+.I ap
+so that the next call returns the next argument.
+The argument
+.I type
+is a type name specified so that the type of a pointer to an object that
+has the specified type can be obtained simply by adding a * to
+.IR type .
+.P
+The first use of the
+.BR va_arg ()
+macro after that of the
+.BR va_start ()
+macro returns the argument after
+.IR last .
+Successive invocations return the values of the remaining arguments.
+.P
+If there is no next argument, or if
+.I type
+is not compatible with the type of the actual next argument (as promoted
+according to the default argument promotions), random errors will occur.
+.P
+If
+.I ap
+is passed to a function that uses
+.BI va_arg( ap , type ),
+then the value of
+.I ap
+is undefined after the return of that function.
+.SS va_end()
+Each invocation of
+.BR va_start ()
+must be matched by a corresponding invocation of
+.BR va_end ()
+in the same function.
+After the call
+.BI va_end( ap )
+the variable
+.I ap
+is undefined.
+Multiple traversals of the list, each
+bracketed by
+.BR va_start ()
+and
+.BR va_end ()
+are possible.
+.BR va_end ()
+may be a macro or a function.
+.SS va_copy()
+The
+.BR va_copy ()
+macro copies the (previously initialized) variable argument list
+.I src
+to
+.IR dest .
+The behavior is as if
+.BR va_start ()
+were applied to
+.I dest
+with the same
+.I last
+argument, followed by the same number of
+.BR va_arg ()
+invocations that was used to reach the current state of
+.IR src .
+.P
+.\" Proposal from clive@demon.net, 1997-02-28
+An obvious implementation would have a
+.I va_list
+be a pointer to the stack frame of the variadic function.
+In such a setup (by far the most common) there seems
+nothing against an assignment
+.P
+.in +4n
+.EX
+va_list aq = ap;
+.EE
+.in
+.P
+Unfortunately, there are also systems that make it an
+array of pointers (of length 1), and there one needs
+.P
+.in +4n
+.EX
+va_list aq;
+*aq = *ap;
+.EE
+.in
+.P
+Finally, on systems where arguments are passed in registers,
+it may be necessary for
+.BR va_start ()
+to allocate memory, store the arguments there, and also
+an indication of which argument is next, so that
+.BR va_arg ()
+can step through the list.
+Now
+.BR va_end ()
+can free the allocated memory again.
+To accommodate this situation, C99 adds a macro
+.BR va_copy (),
+so that the above assignment can be replaced by
+.P
+.in +4n
+.EX
+va_list aq;
+va_copy(aq, ap);
+\&...
+va_end(aq);
+.EE
+.in
+.P
+Each invocation of
+.BR va_copy ()
+must be matched by a corresponding invocation of
+.BR va_end ()
+in the same function.
+Some systems that do not supply
+.BR va_copy ()
+have
+.B __va_copy
+instead, since that was the name used in the draft proposal.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR va_start (),
+.BR va_end (),
+.BR va_copy ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR va_arg ()
+T}	Thread safety	MT-Safe race:ap
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR va_start ()
+.TQ
+.BR va_arg ()
+.TQ
+.BR va_end ()
+C89, POSIX.1-2001.
+.TP
+.BR va_copy ()
+C99, POSIX.1-2001.
+.SH CAVEATS
+Unlike the historical
+.B varargs
+macros, the
+.B stdarg
+macros do not permit programmers to code a function with no fixed
+arguments.
+This problem generates work mainly when converting
+.B varargs
+code to
+.B stdarg
+code, but it also creates difficulties for variadic functions that wish to
+pass all of their arguments on to a function that takes a
+.I va_list
+argument, such as
+.BR vfprintf (3).
+.SH EXAMPLES
+The function
+.I foo
+takes a string of format characters and prints out the argument associated
+with each format character based on the type.
+.P
+.EX
+#include <stdio.h>
+#include <stdarg.h>
+\&
+void
+foo(char *fmt, ...)   /* \[aq]...\[aq] is C syntax for a variadic function */
+\&
+{
+    va_list ap;
+    int d;
+    char c;
+    char *s;
+\&
+    va_start(ap, fmt);
+    while (*fmt)
+        switch (*fmt++) {
+        case \[aq]s\[aq]:              /* string */
+            s = va_arg(ap, char *);
+            printf("string %s\en", s);
+            break;
+        case \[aq]d\[aq]:              /* int */
+            d = va_arg(ap, int);
+            printf("int %d\en", d);
+            break;
+        case \[aq]c\[aq]:              /* char */
+            /* need a cast here since va_arg only
+               takes fully promoted types */
+            c = (char) va_arg(ap, int);
+            printf("char %c\en", c);
+            break;
+        }
+    va_end(ap);
+}
+.EE
+.SH SEE ALSO
+.BR vprintf (3),
+.BR vscanf (3),
+.BR vsyslog (3)
diff --git a/man/man3/stderr.3 b/man/man3/stderr.3
new file mode 100644
index 000000000..752ae2794
--- /dev/null
+++ b/man/man3/stderr.3
@@ -0,0 +1 @@
+.so man3/stdin.3
diff --git a/man/man3/stdin.3 b/man/man3/stdin.3
new file mode 100644
index 000000000..da8a52fa6
--- /dev/null
+++ b/man/man3/stdin.3
@@ -0,0 +1,160 @@
+.\" From dholland@burgundy.eecs.harvard.edu Tue Mar 24 18:08:15 1998
+.\"
+.\" This man page was written in 1998 by David A. Holland
+.\" Polished a bit by aeb.
+.\"
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" Placed in the Public Domain.
+.\" %%%LICENSE_END
+.\"
+.\" 2005-06-16 mtk, mentioned freopen()
+.\" 2007-12-08, mtk, Converted from mdoc to man macros
+.\"
+.TH stdin 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stdin, stdout, stderr \- standard I/O streams
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "extern FILE *" stdin ;
+.BI "extern FILE *" stdout ;
+.BI "extern FILE *" stderr ;
+.fi
+.SH DESCRIPTION
+Under normal circumstances every UNIX program has three streams opened
+for it when it starts up, one for input, one for output, and one for
+printing diagnostic or error messages.
+These are typically attached to
+the user's terminal (see
+.BR tty (4))
+but might instead refer to files or other devices, depending on what
+the parent process chose to set up.
+(See also the "Redirection" section of
+.BR sh (1).)
+.P
+The input stream is referred to as "standard input"; the output stream is
+referred to as "standard output"; and the error stream is referred to
+as "standard error".
+These terms are abbreviated to form the symbols
+used to refer to these files, namely
+.IR stdin ,
+.IR stdout ,
+and
+.IR stderr .
+.P
+Each of these symbols is a
+.BR stdio (3)
+macro of type pointer to
+.IR FILE ,
+and can be used with functions like
+.BR fprintf (3)
+or
+.BR fread (3).
+.P
+Since
+.IR FILE s
+are a buffering wrapper around UNIX file descriptors, the
+same underlying files may also be accessed using the raw UNIX file
+interface, that is, the functions like
+.BR read (2)
+and
+.BR lseek (2).
+.P
+On program startup, the integer file descriptors
+associated with the streams
+.IR stdin ,
+.IR stdout ,
+and
+.I stderr
+are 0, 1, and 2, respectively.
+The preprocessor symbols
+.BR STDIN_FILENO ,
+.BR STDOUT_FILENO ,
+and
+.B STDERR_FILENO
+are defined with these values in
+.IR <unistd.h> .
+(Applying
+.BR freopen (3)
+to one of these streams can change the file descriptor number
+associated with the stream.)
+.P
+Note that mixing use of
+.IR FILE s
+and raw file descriptors can produce
+unexpected results and should generally be avoided.
+(For the masochistic among you: POSIX.1, section 8.2.3, describes
+in detail how this interaction is supposed to work.)
+A general rule is that file descriptors are handled in the kernel,
+while stdio is just a library.
+This means for example, that after an
+.BR exec (3),
+the child inherits all open file descriptors, but all old streams
+have become inaccessible.
+.P
+Since the symbols
+.IR stdin ,
+.IR stdout ,
+and
+.I stderr
+are specified to be macros, assigning to them is nonportable.
+The standard streams can be made to refer to different files
+with help of the library function
+.BR freopen (3),
+specially introduced to make it possible to reassign
+.IR stdin ,
+.IR stdout ,
+and
+.IR stderr .
+The standard streams are closed by a call to
+.BR exit (3)
+and by normal program termination.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.P
+The standards also stipulate that these three
+streams shall be open at program startup.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH NOTES
+The stream
+.I stderr
+is unbuffered.
+The stream
+.I stdout
+is line-buffered when it points to a terminal.
+Partial lines will not
+appear until
+.BR fflush (3)
+or
+.BR exit (3)
+is called, or a newline is printed.
+This can produce unexpected
+results, especially with debugging output.
+The buffering mode of the standard streams (or any other stream)
+can be changed using the
+.BR setbuf (3)
+or
+.BR setvbuf (3)
+call.
+Note that in case
+.I stdin
+is associated with a terminal, there may also be input buffering
+in the terminal driver, entirely unrelated to stdio buffering.
+(Indeed, normally terminal input is line buffered in the kernel.)
+This kernel input handling can be modified using calls like
+.BR tcsetattr (3);
+see also
+.BR stty (1),
+and
+.BR termios (3).
+.SH SEE ALSO
+.BR csh (1),
+.BR sh (1),
+.BR open (2),
+.BR fopen (3),
+.BR stdio (3)
diff --git a/man/man3/stdio.3 b/man/man3/stdio.3
new file mode 100644
index 000000000..a76b77546
--- /dev/null
+++ b/man/man3/stdio.3
@@ -0,0 +1,353 @@
+'\" t
+.\" Copyright (c) 1990, 1991 Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)stdio.3	6.5 (Berkeley) 5/6/91
+.\"
+.\" Converted for Linux, Mon Nov 29 16:07:22 1993, faith@cs.unc.edu
+.\" Modified, 2001-12-26, aeb
+.\"
+.TH stdio 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stdio \- standard input/output library functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "FILE *" stdin ;
+.BI "FILE *" stdout ;
+.BI "FILE *" stderr ;
+.fi
+.SH DESCRIPTION
+The standard I/O library provides a simple and efficient buffered stream
+I/O interface.
+Input and output is mapped into logical data streams and the
+physical I/O characteristics are concealed.
+The functions and macros are
+listed below; more information is available from the individual man pages.
+.P
+A stream is associated with an external file (which may be a physical
+device) by
+.I opening
+a file, which may involve creating a new file.
+Creating an existing file
+causes its former contents to be discarded.
+If a file can support positioning requests (such as a disk file,
+as opposed to a terminal), then a
+.I file position indicator
+associated with the stream is positioned at the start of the file (byte
+zero), unless the file is opened with append mode.
+If append mode is used,
+it is unspecified whether the position indicator will be placed at the
+start or the end of the file.
+The position indicator is maintained by
+subsequent reads, writes, and positioning requests.
+All input occurs as if the characters were read by successive calls to the
+.BR fgetc (3)
+function; all output takes place as if all characters were written by
+successive calls to the
+.BR fputc (3)
+function.
+.P
+A file is disassociated from a stream by
+.I closing
+the file.
+Output streams are flushed (any unwritten buffer contents are
+transferred to the host environment) before the stream is disassociated from
+the file.
+The value of a pointer to a
+.I FILE
+object is indeterminate after a file is closed (garbage).
+.P
+A file may be subsequently reopened, by the same or another program
+execution, and its contents reclaimed or modified (if it can be
+repositioned at the start).
+If the main function returns to its original
+caller, or the
+.BR exit (3)
+function is called, all open files are closed (hence all output streams are
+flushed) before program termination.
+Other methods of program termination,
+such as
+.BR abort (3)
+do not bother about closing files properly.
+.P
+At program startup, three text streams are predefined and need not be
+opened explicitly:
+.I standard input
+(for reading conventional input),
+.I standard output
+(for writing conventional output), and
+.I standard error
+(for writing diagnostic output).
+These streams are abbreviated
+.IR stdin ,
+.IR stdout ,
+and
+.IR stderr .
+When opened, the standard error stream is not fully buffered; the standard
+input and output streams are fully buffered if and only if the streams do
+not refer to an interactive device.
+.P
+Output streams that refer to terminal devices are always line buffered by
+default; pending output to such streams is written automatically whenever
+an input stream that refers to a terminal device is read.
+In cases where a
+large amount of computation is done after printing part of a line on an
+output terminal, it is necessary to
+.BR fflush (3)
+the standard output before going off and computing so that the output will
+appear.
+.P
+The
+.I stdio
+library is a part of the library
+.B libc
+and routines are automatically loaded as needed by
+.BR cc (1).
+The
+SYNOPSIS
+sections of the following manual pages indicate which include files are to
+be used, what the compiler declaration for the function looks like and
+which external variables are of interest.
+.P
+The following are defined as macros; these names may not be reused without
+first removing their current definitions with
+.BR #undef :
+.BR BUFSIZ ,
+.BR EOF ,
+.BR FILENAME_MAX ,
+.BR FOPEN_MAX ,
+.BR L_cuserid ,
+.BR L_ctermid ,
+.BR L_tmpnam ,
+.BR NULL ,
+.BR SEEK_END ,
+.BR SEEK_SET ,
+.BR SEEK_CUR ,
+.BR TMP_MAX ,
+.BR clearerr ,
+.BR feof ,
+.BR ferror ,
+.BR fileno ,
+.\" Not on Linux: .BR fropen ,
+.\" Not on Linux: .BR fwopen ,
+.BR getc ,
+.BR getchar ,
+.BR putc ,
+.BR putchar ,
+.BR stderr ,
+.BR stdin ,
+.BR stdout .
+Function versions of the macro functions
+.BR feof ,
+.BR ferror ,
+.BR clearerr ,
+.BR fileno ,
+.BR getc ,
+.BR getchar ,
+.BR putc ,
+and
+.B putchar
+exist and will be used if the macros definitions are explicitly removed.
+.SS List of functions
+.TS
+;
+lb lbx
+l l.
+Function	Description
+_
+\fBclearerr\fP(3)	T{
+check and reset stream status
+T}
+\fBfclose\fP(3)	T{
+close a stream
+T}
+\fBfdopen\fP(3)	T{
+stream open functions
+T}
+\fBfeof\fP(3)	T{
+check and reset stream status
+T}
+\fBferror\fP(3)	T{
+check and reset stream status
+T}
+\fBfflush\fP(3)	T{
+flush a stream
+T}
+\fBfgetc\fP(3)	T{
+get next character or word from input stream
+T}
+\fBfgetpos\fP(3)	T{
+reposition a stream
+T}
+\fBfgets\fP(3)	T{
+get a line from a stream
+T}
+\fBfileno\fP(3)	T{
+return the integer descriptor of the argument stream
+T}
+\fBfmemopen\fP(3)	T{
+open memory as stream
+T}
+\fBfopen\fP(3)	T{
+stream open functions
+T}
+\fBfopencookie\fP(3)	T{
+open a custom stream
+T}
+\fBfprintf\fP(3)	T{
+formatted output conversion
+T}
+\fBfpurge\fP(3)	T{
+flush a stream
+T}
+\fBfputc\fP(3)	T{
+output a character or word to a stream
+T}
+\fBfputs\fP(3)	T{
+output a line to a stream
+T}
+\fBfread\fP(3)	T{
+binary stream input/output
+T}
+\fBfreopen\fP(3)	T{
+stream open functions
+T}
+\fBfscanf\fP(3)	T{
+input format conversion
+T}
+\fBfseek\fP(3)	T{
+reposition a stream
+T}
+\fBfsetpos\fP(3)	T{
+reposition a stream
+T}
+\fBftell\fP(3)	T{
+reposition a stream
+T}
+\fBfwrite\fP(3)	T{
+binary stream input/output
+T}
+\fBgetc\fP(3)	T{
+get next character or word from input stream
+T}
+\fBgetchar\fP(3)	T{
+get next character or word from input stream
+T}
+\fBgets\fP(3)	T{
+get a line from a stream
+T}
+\fBgetw\fP(3)	T{
+get next character or word from input stream
+T}
+\fBmktemp\fP(3)	T{
+make temporary filename (unique)
+T}
+\fBopen_memstream\fP(3)	T{
+open a dynamic memory buffer stream
+T}
+\fBopen_wmemstream\fP(3)	T{
+open a dynamic memory buffer stream
+T}
+\fBperror\fP(3)	T{
+system error messages
+T}
+\fBprintf\fP(3)	T{
+formatted output conversion
+T}
+\fBputc\fP(3)	T{
+output a character or word to a stream
+T}
+\fBputchar\fP(3)	T{
+output a character or word to a stream
+T}
+\fBputs\fP(3)	T{
+output a line to a stream
+T}
+\fBputw\fP(3)	T{
+output a character or word to a stream
+T}
+\fBremove\fP(3)	T{
+remove directory entry
+T}
+\fBrewind\fP(3)	T{
+reposition a stream
+T}
+\fBscanf\fP(3)	T{
+input format conversion
+T}
+\fBsetbuf\fP(3)	T{
+stream buffering operations
+T}
+\fBsetbuffer\fP(3)	T{
+stream buffering operations
+T}
+\fBsetlinebuf\fP(3)	T{
+stream buffering operations
+T}
+\fBsetvbuf\fP(3)	T{
+stream buffering operations
+T}
+\fBsprintf\fP(3)	T{
+formatted output conversion
+T}
+\fBsscanf\fP(3)	T{
+input format conversion
+T}
+\fBstrerror\fP(3)	T{
+system error messages
+T}
+\fBsys_errlist\fP(3)	T{
+system error messages
+T}
+\fBsys_nerr\fP(3)	T{
+system error messages
+T}
+\fBtempnam\fP(3)	T{
+temporary file routines
+T}
+\fBtmpfile\fP(3)	T{
+temporary file routines
+T}
+\fBtmpnam\fP(3)	T{
+temporary file routines
+T}
+\fBungetc\fP(3)	T{
+un-get character from input stream
+T}
+\fBvfprintf\fP(3)	T{
+formatted output conversion
+T}
+\fBvfscanf\fP(3)	T{
+input format conversion
+T}
+\fBvprintf\fP(3)	T{
+formatted output conversion
+T}
+\fBvscanf\fP(3)	T{
+input format conversion
+T}
+\fBvsprintf\fP(3)	T{
+formatted output conversion
+T}
+\fBvsscanf\fP(3)	T{
+input format conversion
+T}
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH SEE ALSO
+.BR close (2),
+.BR open (2),
+.BR read (2),
+.BR write (2),
+.BR stdout (3),
+.BR unlocked_stdio (3)
diff --git a/man/man3/stdio_ext.3 b/man/man3/stdio_ext.3
new file mode 100644
index 000000000..815135dd1
--- /dev/null
+++ b/man/man3/stdio_ext.3
@@ -0,0 +1,137 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH stdio_ext 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+__fbufsize, __flbf, __fpending, __fpurge, __freadable,
+__freading, __fsetlocking, __fwritable, __fwriting, _flushlbf \-
+interfaces to stdio FILE structure
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <stdio_ext.h>
+.P
+.BI "size_t __fbufsize(FILE *" stream );
+.BI "size_t __fpending(FILE *" stream );
+.BI "int __flbf(FILE *" stream );
+.BI "int __freadable(FILE *" stream );
+.BI "int __fwritable(FILE *" stream );
+.BI "int __freading(FILE *" stream );
+.BI "int __fwriting(FILE *" stream );
+.BI "int __fsetlocking(FILE *" stream ", int " type );
+.B "void _flushlbf(void);"
+.BI "void __fpurge(FILE *" stream );
+.fi
+.SH DESCRIPTION
+Solaris introduced routines to allow portable access to the
+internals of the
+.I FILE
+structure, and glibc also implemented these.
+.P
+The
+.BR __fbufsize ()
+function returns the size of the buffer currently used
+by the given stream.
+.P
+The
+.BR __fpending ()
+function returns the number of bytes in the output buffer.
+For wide-oriented streams the unit is wide characters.
+This function is undefined on buffers in reading mode,
+or opened read-only.
+.P
+The
+.BR __flbf ()
+function returns a nonzero value if the stream is line-buffered,
+and zero otherwise.
+.P
+The
+.BR __freadable ()
+function returns a nonzero value if the stream allows reading,
+and zero otherwise.
+.P
+The
+.BR __fwritable ()
+function returns a nonzero value if the stream allows writing,
+and zero otherwise.
+.P
+The
+.BR __freading ()
+function returns a nonzero value if the stream is read-only, or
+if the last operation on the stream was a read operation,
+and zero otherwise.
+.P
+The
+.BR __fwriting ()
+function returns a nonzero value if the stream is write-only (or
+append-only), or if the last operation on the stream was a write
+operation, and zero otherwise.
+.P
+The
+.BR __fsetlocking ()
+function can be used to select the desired type of locking on the stream.
+It returns the current type.
+The
+.I type
+argument can take the following three values:
+.TP
+.B FSETLOCKING_INTERNAL
+Perform implicit locking around every operation on the given stream
+(except for the *_unlocked ones).
+This is the default.
+.TP
+.B FSETLOCKING_BYCALLER
+The caller will take care of the locking (possibly using
+.BR flockfile (3)
+in case there is more than one thread), and the stdio routines
+will not do locking until the state is reset to
+.BR FSETLOCKING_INTERNAL .
+.TP
+.B FSETLOCKING_QUERY
+Don't change the type of locking.
+(Only return it.)
+.P
+The
+.BR _flushlbf ()
+function flushes all line-buffered streams.
+(Presumably so that
+output to a terminal is forced out, say before reading keyboard input.)
+.P
+The
+.BR __fpurge ()
+function discards the contents of the stream's buffer.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR __fbufsize (),
+.BR __fpending (),
+.BR __fpurge (),
+.BR __fsetlocking ()
+T}	Thread safety	MT-Safe race:stream
+T{
+.na
+.nh
+.BR __flbf (),
+.BR __freadable (),
+.BR __freading (),
+.BR __fwritable (),
+.BR __fwriting (),
+.BR _flushlbf ()
+T}	Thread safety	MT-Safe
+.TE
+.SH SEE ALSO
+.BR flockfile (3),
+.BR fpurge (3)
diff --git a/man/man3/stdout.3 b/man/man3/stdout.3
new file mode 100644
index 000000000..752ae2794
--- /dev/null
+++ b/man/man3/stdout.3
@@ -0,0 +1 @@
+.so man3/stdin.3
diff --git a/man/man3/stpcpy.3 b/man/man3/stpcpy.3
new file mode 100644
index 000000000..ff7476a84
--- /dev/null
+++ b/man/man3/stpcpy.3
@@ -0,0 +1 @@
+.so man3/strcpy.3
diff --git a/man/man3/stpncpy.3 b/man/man3/stpncpy.3
new file mode 100644
index 000000000..9544682fc
--- /dev/null
+++ b/man/man3/stpncpy.3
@@ -0,0 +1,178 @@
+'\" t
+.\" Copyright 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH stpncpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stpncpy, strncpy
+\-
+fill a fixed-size buffer with non-null bytes from a string,
+padding with null bytes as needed
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strncpy(char " dst "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "              size_t " dsize );
+.BI "char *stpncpy(char " dst "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "              size_t " dsize );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR stpncpy ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+These functions copy non-null bytes from the string pointed to by
+.I src
+into the array pointed to by
+.IR dst .
+If the source has too few non-null bytes to fill the destination,
+the functions pad the destination with trailing null bytes.
+If the destination buffer,
+limited by its size,
+isn't large enough to hold the copy,
+the resulting character sequence is truncated.
+For the difference between the two functions, see RETURN VALUE.
+.P
+An implementation of these functions might be:
+.P
+.in +4n
+.EX
+char *
+strncpy(char *restrict dst, const char *restrict src, size_t dsize)
+{
+    stpncpy(dst, src, dsize);
+    return dst;
+}
+\&
+char *
+stpncpy(char *restrict dst, const char *restrict src, size_t dsize)
+{
+    size_t  dlen;
+\&
+    dlen = strnlen(src, dsize);
+    return memset(mempcpy(dst, src, dlen), 0, dsize \- dlen);
+}
+.EE
+.in
+.SH RETURN VALUE
+.TP
+.BR strncpy ()
+returns
+.IR dst .
+.TP
+.BR stpncpy ()
+returns a pointer to
+one after the last character in the destination character sequence.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR stpncpy (),
+.BR strncpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR strncpy ()
+C11, POSIX.1-2008.
+.TP
+.BR stpncpy ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR strncpy ()
+C89, POSIX.1-2001, SVr4, 4.3BSD.
+.TP
+.BR stpncpy ()
+glibc 1.07.
+POSIX.1-2008.
+.SH CAVEATS
+The name of these functions is confusing.
+These functions produce a null-padded character sequence,
+not a string (see
+.BR string_copying (7)).
+For example:
+.P
+.in +4n
+.EX
+strncpy(buf, "1", 5);       // { \[aq]1\[aq],   0,   0,   0,   0 }
+strncpy(buf, "1234", 5);    // { \[aq]1\[aq], \[aq]2\[aq], \[aq]3\[aq], \[aq]4\[aq],   0 }
+strncpy(buf, "12345", 5);   // { \[aq]1\[aq], \[aq]2\[aq], \[aq]3\[aq], \[aq]4\[aq], \[aq]5\[aq] }
+strncpy(buf, "123456", 5);  // { \[aq]1\[aq], \[aq]2\[aq], \[aq]3\[aq], \[aq]4\[aq], \[aq]5\[aq] }
+.EE
+.in
+.P
+It's impossible to distinguish truncation by the result of the call,
+from a character sequence that just fits the destination buffer;
+truncation should be detected by
+comparing the length of the input string
+with the size of the destination buffer.
+.P
+If you're going to use this function in chained calls,
+it would be useful to develop a similar function that accepts
+a pointer to the end (one after the last element) of the destination buffer
+instead of its size.
+.SH EXAMPLES
+.\" SRC BEGIN (stpncpy.c)
+.EX
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(void)
+{
+    char    *p;
+    char    buf1[20];
+    char    buf2[20];
+    size_t  len;
+\&
+    if (sizeof(buf2) < strlen("Hello world!"))
+        errx("strncpy: truncating character sequence");
+    strncpy(buf2, "Hello world!", sizeof(buf2));
+    len = strnlen(buf2, sizeof(buf2));
+\&
+    printf("[len = %zu]: ", len);
+    fwrite(buf2, 1, len, stdout);
+    putchar(\[aq]\en\[aq]);
+\&
+    if (sizeof(buf1) < strlen("Hello world!"))
+        errx("stpncpy: truncating character sequence");
+    p = stpncpy(buf1, "Hello world!", sizeof(buf1));
+    len = p \- buf1;
+\&
+    printf("[len = %zu]: ", len);
+    fwrite(buf1, 1, len, stdout);
+    putchar(\[aq]\en\[aq]);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR wcpncpy (3),
+.BR string_copying (7)
diff --git a/man/man3/strcasecmp.3 b/man/man3/strcasecmp.3
new file mode 100644
index 000000000..d2fe959f0
--- /dev/null
+++ b/man/man3/strcasecmp.3
@@ -0,0 +1,112 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:12:45 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strcasecmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strcasecmp, strncasecmp \- compare two strings ignoring case
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <strings.h>
+.P
+.BI "int strcasecmp(const char *" s1 ", const char *" s2 );
+.BI "int strncasecmp(const char " s1 [. n "], const char " s2 [. n "], \
+size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR strcasecmp ()
+function performs a byte-by-byte comparison of the strings
+.I s1
+and
+.IR s2 ,
+ignoring the case of the characters.
+It returns an integer
+less than, equal to, or greater than zero if
+.I s1
+is found,
+respectively, to be less than, to match, or be greater than
+.IR s2 .
+.P
+The
+.BR strncasecmp ()
+function is similar, except that it compares
+no more than
+.I n
+bytes of
+.I s1
+and
+.IR s2 .
+.SH RETURN VALUE
+The
+.BR strcasecmp ()
+and
+.BR strncasecmp ()
+functions return
+an integer less than, equal to, or greater than zero if
+.I s1
+is, after ignoring case, found to be
+less than, to match, or be greater than
+.IR s2 ,
+respectively.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strcasecmp (),
+.BR strncasecmp ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+4.4BSD, POSIX.1-2001.
+.P
+The
+.BR strcasecmp ()
+and
+.BR strncasecmp ()
+functions first appeared in 4.4BSD, where they were declared in
+.IR <string.h> .
+Thus, for reasons of historical compatibility, the glibc
+.I <string.h>
+header file also declares these functions, if the
+.B _DEFAULT_SOURCE
+(or, in glibc 2.19 and earlier,
+.BR _BSD_SOURCE )
+feature test macro is defined.
+.P
+The POSIX.1-2008 standard says of these functions:
+.P
+.RS
+When the
+.B LC_CTYPE
+category of the locale being used is from the POSIX locale,
+these functions shall behave as if the strings had been converted
+to lowercase and then a byte comparison performed.
+Otherwise, the results are unspecified.
+.RE
+.SH SEE ALSO
+.BR memcmp (3),
+.BR strcmp (3),
+.BR strcoll (3),
+.BR string (3),
+.BR strncmp (3),
+.BR wcscasecmp (3),
+.BR wcsncasecmp (3)
diff --git a/man/man3/strcasestr.3 b/man/man3/strcasestr.3
new file mode 100644
index 000000000..2feb2c57e
--- /dev/null
+++ b/man/man3/strcasestr.3
@@ -0,0 +1 @@
+.so man3/strstr.3
diff --git a/man/man3/strcat.3 b/man/man3/strcat.3
new file mode 100644
index 000000000..ff7476a84
--- /dev/null
+++ b/man/man3/strcat.3
@@ -0,0 +1 @@
+.so man3/strcpy.3
diff --git a/man/man3/strchr.3 b/man/man3/strchr.3
new file mode 100644
index 000000000..55f6add88
--- /dev/null
+++ b/man/man3/strchr.3
@@ -0,0 +1,131 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Mon Apr 12 12:51:24 1993, David Metcalfe
+.\" 2006-05-19, Justin Pryzby <pryzbyj@justinpryzby.com>
+.\"	Document strchrnul(3).
+.\"
+.TH strchr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strchr, strrchr, strchrnul \- locate character in string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strchr(const char *" s ", int " c );
+.BI "char *strrchr(const char *" s ", int " c );
+.P
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <string.h>
+.P
+.BI "char *strchrnul(const char *" s ", int " c );
+.fi
+.SH DESCRIPTION
+The
+.BR strchr ()
+function returns a pointer to the first occurrence
+of the character
+.I c
+in the string
+.IR s .
+.P
+The
+.BR strrchr ()
+function returns a pointer to the last occurrence
+of the character
+.I c
+in the string
+.IR s .
+.P
+The
+.BR strchrnul ()
+function is like
+.BR strchr ()
+except that if
+.I c
+is not found in
+.IR s ,
+then it returns a pointer to the null byte
+at the end of
+.IR s ,
+rather than NULL.
+.P
+Here "character" means "byte"; these functions do not work with
+wide or multibyte characters.
+.SH RETURN VALUE
+The
+.BR strchr ()
+and
+.BR strrchr ()
+functions return a pointer to
+the matched character or NULL if the character is not found.
+The terminating null byte is considered part of the string,
+so that if
+.I c
+is specified as \[aq]\e0\[aq],
+these functions return a pointer to the terminator.
+.P
+The
+.BR strchrnul ()
+function returns a pointer to the matched character,
+or a pointer to the null byte at the end of
+.I s
+(i.e.,
+.IR "s+strlen(s)" )
+if the character is not found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strchr (),
+.BR strrchr (),
+.BR strchrnul ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR strchr ()
+.TQ
+.BR strrchr ()
+C11, POSIX.1-2008.
+.TP
+.BR strchrnul ()
+GNU.
+.SH HISTORY
+.TP
+.BR strchr ()
+.TQ
+.BR strrchr ()
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.TP
+.BR strchrnul ()
+glibc 2.1.1,
+FreeBSD 10,
+NetBSD 8.
+.SH SEE ALSO
+.BR memchr (3),
+.BR string (3),
+.BR strlen (3),
+.BR strpbrk (3),
+.BR strsep (3),
+.BR strspn (3),
+.BR strstr (3),
+.BR strtok (3),
+.BR wcschr (3),
+.BR wcsrchr (3)
diff --git a/man/man3/strchrnul.3 b/man/man3/strchrnul.3
new file mode 100644
index 000000000..322b7a896
--- /dev/null
+++ b/man/man3/strchrnul.3
@@ -0,0 +1 @@
+.so man3/strchr.3
diff --git a/man/man3/strcmp.3 b/man/man3/strcmp.3
new file mode 100644
index 000000000..3e910d97b
--- /dev/null
+++ b/man/man3/strcmp.3
@@ -0,0 +1,208 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:08:52 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2001-08-31, aeb
+.\"
+.TH strcmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strcmp, strncmp \- compare two strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "int strcmp(const char *" s1 ", const char *" s2 );
+.BI "int strncmp(const char " s1 [. n "], const char " s2 [. n "], size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR strcmp ()
+function compares the two strings
+.I s1
+and
+.IR s2 .
+The locale is not taken into account (for a locale-aware comparison, see
+.BR strcoll (3)).
+The comparison is done using unsigned characters.
+.P
+.BR strcmp ()
+returns an integer indicating the result of the comparison, as follows:
+.IP \[bu] 3
+0, if the
+.I s1
+and
+.I s2
+are equal;
+.IP \[bu]
+a negative value if
+.I s1
+is less than
+.IR s2 ;
+.IP \[bu]
+a positive value if
+.I s1
+is greater than
+.IR s2 .
+.P
+The
+.BR strncmp ()
+function is similar, except it compares
+only the first (at most)
+.I n
+bytes of
+.I s1
+and
+.IR s2 .
+.SH RETURN VALUE
+The
+.BR strcmp ()
+and
+.BR strncmp ()
+functions return an integer
+less than, equal to, or greater than zero if
+.I s1
+(or the first
+.I n
+bytes thereof) is found, respectively, to be less than, to
+match, or be greater than
+.IR s2 .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strcmp (),
+.BR strncmp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+POSIX.1 specifies only that:
+.RS
+.P
+The sign of a nonzero return value shall be determined by the sign
+of the difference between the values of the first pair of bytes
+(both interpreted as type
+.IR "unsigned char" )
+that differ in the strings being compared.
+.RE
+.P
+In glibc, as in most other implementations,
+the return value is the arithmetic result of subtracting
+the last compared byte in
+.I s2
+from the last compared byte in
+.IR s1 .
+(If the two characters are equal, this difference is 0.)
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH EXAMPLES
+The program below can be used to demonstrate the operation of
+.BR strcmp ()
+(when given two arguments) and
+.BR strncmp ()
+(when given three arguments).
+First, some examples using
+.BR strcmp ():
+.P
+.in +4n
+.EX
+$ \fB./string_comp ABC ABC\fP
+<str1> and <str2> are equal
+$ \fB./string_comp ABC AB\fP      # \[aq]C\[aq] is ASCII 67; \[aq]C\[aq] \- \[aq]\e0\[aq] = 67
+<str1> is greater than <str2> (67)
+$ \fB./string_comp ABA ABZ\fP     # \[aq]A\[aq] is ASCII 65; \[aq]Z\[aq] is ASCII 90
+<str1> is less than <str2> (\-25)
+$ \fB./string_comp ABJ ABC\fP
+<str1> is greater than <str2> (7)
+$ .\fB/string_comp $\[aq]\e201\[aq] A\fP   # 0201 \- 0101 = 0100 (or 64 decimal)
+<str1> is greater than <str2> (64)
+.EE
+.in
+.P
+The last example uses
+.BR bash (1)-specific
+syntax to produce a string containing an 8-bit ASCII code;
+the result demonstrates that the string comparison uses unsigned
+characters.
+.P
+And then some examples using
+.BR strncmp ():
+.P
+.in +4n
+.EX
+$ \fB./string_comp ABC AB 3\fP
+<str1> is greater than <str2> (67)
+$ \fB./string_comp ABC AB 2\fP
+<str1> and <str2> are equal in the first 2 bytes
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (string_comp.c)
+.EX
+/* string_comp.c
+\&
+   Licensed under GNU General Public License v2 or later.
+*/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int res;
+\&
+    if (argc < 3) {
+        fprintf(stderr, "Usage: %s <str1> <str2> [<len>]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (argc == 3)
+        res = strcmp(argv[1], argv[2]);
+    else
+        res = strncmp(argv[1], argv[2], atoi(argv[3]));
+\&
+    if (res == 0) {
+        printf("<str1> and <str2> are equal");
+        if (argc > 3)
+            printf(" in the first %d bytes\en", atoi(argv[3]));
+        printf("\en");
+    } else if (res < 0) {
+        printf("<str1> is less than <str2> (%d)\en", res);
+    } else {
+        printf("<str1> is greater than <str2> (%d)\en", res);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR memcmp (3),
+.BR strcasecmp (3),
+.BR strcoll (3),
+.BR string (3),
+.BR strncasecmp (3),
+.BR strverscmp (3),
+.BR wcscmp (3),
+.BR wcsncmp (3),
+.BR ascii (7)
diff --git a/man/man3/strcoll.3 b/man/man3/strcoll.3
new file mode 100644
index 000000000..9706a6e7b
--- /dev/null
+++ b/man/man3/strcoll.3
@@ -0,0 +1,86 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:40:44 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strcoll 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strcoll \- compare two strings using the current locale
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "int strcoll(const char *" s1 ", const char *" s2 );
+.fi
+.SH DESCRIPTION
+The
+.BR strcoll ()
+function compares the two strings
+.I s1
+and
+.IR s2 .
+It returns an integer less than, equal to, or greater
+than zero if
+.I s1
+is found, respectively, to be less than,
+to match, or be greater than
+.IR s2 .
+The comparison is based on
+strings interpreted as appropriate for the program's current locale
+for category
+.BR LC_COLLATE .
+(See
+.BR setlocale (3).)
+.SH RETURN VALUE
+The
+.BR strcoll ()
+function returns an integer less than, equal to,
+or greater than zero if
+.I s1
+is found, respectively, to be less
+than, to match, or be greater than
+.IR s2 ,
+when both are interpreted
+as appropriate for the current locale.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strcoll ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH NOTES
+In the
+.I "POSIX"
+or
+.I "C"
+locales
+.BR strcoll ()
+is equivalent to
+.BR strcmp (3).
+.SH SEE ALSO
+.BR memcmp (3),
+.BR setlocale (3),
+.BR strcasecmp (3),
+.BR strcmp (3),
+.BR string (3),
+.BR strxfrm (3)
diff --git a/man/man3/strcpy.3 b/man/man3/strcpy.3
new file mode 100644
index 000000000..1cfde931b
--- /dev/null
+++ b/man/man3/strcpy.3
@@ -0,0 +1,204 @@
+'\" t
+.\" Copyright 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH strcpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stpcpy, strcpy, strcat \- copy or catenate a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *stpcpy(char *restrict " dst ", const char *restrict " src );
+.BI "char *strcpy(char *restrict " dst ", const char *restrict " src );
+.BI "char *strcat(char *restrict " dst ", const char *restrict " src );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR stpcpy ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+.TP
+.BR stpcpy ()
+.TQ
+.BR strcpy ()
+These functions copy the string pointed to by
+.IR src ,
+into a string
+at the buffer pointed to by
+.IR dst .
+The programmer is responsible for allocating a destination buffer large enough,
+that is,
+.IR "strlen(src) + 1" .
+For the difference between the two functions, see RETURN VALUE.
+.TP
+.BR strcat ()
+This function catenates the string pointed to by
+.IR src ,
+after the string pointed to by
+.I dst
+(overwriting its terminating null byte).
+The programmer is responsible for allocating a destination buffer large enough,
+that is,
+.IR "strlen(dst) + strlen(src) + 1" .
+.P
+An implementation of these functions might be:
+.P
+.in +4n
+.EX
+char *
+stpcpy(char *restrict dst, const char *restrict src)
+{
+    char  *p;
+\&
+    p = mempcpy(dst, src, strlen(src));
+    *p = \[aq]\e0\[aq];
+\&
+    return p;
+}
+\&
+char *
+strcpy(char *restrict dst, const char *restrict src)
+{
+    stpcpy(dst, src);
+    return dst;
+}
+\&
+char *
+strcat(char *restrict dst, const char *restrict src)
+{
+    stpcpy(dst + strlen(dst), src);
+    return dst;
+}
+.EE
+.in
+.SH RETURN VALUE
+.TP
+.BR stpcpy ()
+This function returns
+a pointer to the terminating null byte of the copied string.
+.TP
+.BR strcpy ()
+.TQ
+.BR strcat ()
+These functions return
+.IR dst .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR stpcpy (),
+.BR strcpy (),
+.BR strcat ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR stpcpy ()
+POSIX.1-2008.
+.TP
+.BR strcpy ()
+.TQ
+.BR strcat ()
+C11, POSIX.1-2008.
+.SH STANDARDS
+.TP
+.BR stpcpy ()
+POSIX.1-2008.
+.TP
+.BR strcpy ()
+.TQ
+.BR strcat ()
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH CAVEATS
+The strings
+.I src
+and
+.I dst
+may not overlap.
+.P
+If the destination buffer is not large enough,
+the behavior is undefined.
+See
+.B _FORTIFY_SOURCE
+in
+.BR feature_test_macros (7).
+.P
+.BR strcat ()
+can be very inefficient.
+Read about
+.UR https://www.joelonsoftware.com/\:2001/12/11/\:back\-to\-basics/
+Shlemiel the painter
+.UE .
+.SH EXAMPLES
+.\" SRC BEGIN (strcpy.c)
+.EX
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(void)
+{
+    char    *p;
+    char    *buf1;
+    char    *buf2;
+    size_t  len, maxsize;
+\&
+    maxsize = strlen("Hello ") + strlen("world") + strlen("!") + 1;
+    buf1 = malloc(sizeof(*buf1) * maxsize);
+    if (buf1 == NULL)
+        err(EXIT_FAILURE, "malloc()");
+    buf2 = malloc(sizeof(*buf2) * maxsize);
+    if (buf2 == NULL)
+        err(EXIT_FAILURE, "malloc()");
+\&
+    p = buf1;
+    p = stpcpy(p, "Hello ");
+    p = stpcpy(p, "world");
+    p = stpcpy(p, "!");
+    len = p \- buf1;
+\&
+    printf("[len = %zu]: ", len);
+    puts(buf1);  // "Hello world!"
+    free(buf1);
+\&
+    strcpy(buf2, "Hello ");
+    strcat(buf2, "world");
+    strcat(buf2, "!");
+    len = strlen(buf2);
+\&
+    printf("[len = %zu]: ", len);
+    puts(buf2);  // "Hello world!"
+    free(buf2);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR strdup (3),
+.BR string (3),
+.BR wcscpy (3),
+.BR string_copying (7)
diff --git a/man/man3/strcspn.3 b/man/man3/strcspn.3
new file mode 100644
index 000000000..26284f29a
--- /dev/null
+++ b/man/man3/strcspn.3
@@ -0,0 +1 @@
+.so man3/strspn.3
diff --git a/man/man3/strdup.3 b/man/man3/strdup.3
new file mode 100644
index 000000000..3e338b4f9
--- /dev/null
+++ b/man/man3/strdup.3
@@ -0,0 +1,145 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:41:34 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Wed Oct 17 01:12:26 2001 by John Levon <moz@compsoc.man.ac.uk>
+.TH strdup 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strdup, strndup, strdupa, strndupa \- duplicate a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strdup(const char *" s );
+.P
+.BI "char *strndup(const char " s [. n "], size_t " n );
+.BI "char *strdupa(const char *" s );
+.BI "char *strndupa(const char " s [. n "], size_t " n );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strdup ():
+.nf
+    _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.P
+.BR strndup ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.P
+.BR strdupa (),
+.BR strndupa ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR strdup ()
+function returns a pointer to a new string which
+is a duplicate of the string
+.IR s .
+Memory for the new string is
+obtained with
+.BR malloc (3),
+and can be freed with
+.BR free (3).
+.P
+The
+.BR strndup ()
+function is similar, but copies at most
+.I n
+bytes.
+If
+.I s
+is longer than
+.IR n ,
+only
+.I n
+bytes are copied, and a terminating null byte (\[aq]\e0\[aq]) is added.
+.P
+.BR strdupa ()
+and
+.BR strndupa ()
+are similar, but use
+.BR alloca (3)
+to allocate the buffer.
+.SH RETURN VALUE
+On success, the
+.BR strdup ()
+function returns a pointer to the duplicated
+string.
+It returns NULL if insufficient memory was available, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient memory available to allocate duplicate string.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strdup (),
+.BR strndup (),
+.BR strdupa (),
+.BR strndupa ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR strdup ()
+.TQ
+.BR strndup ()
+POSIX.1-2008.
+.TP
+.BR strdupa ()
+.TQ
+.BR strndupa ()
+GNU.
+.SH HISTORY
+.TP
+.BR strdup ()
+SVr4, 4.3BSD-Reno, POSIX.1-2001.
+.TP
+.BR strndup ()
+POSIX.1-2008.
+.TP
+.BR strdupa ()
+.TQ
+.BR strndupa ()
+GNU.
+.SH SEE ALSO
+.BR alloca (3),
+.BR calloc (3),
+.BR free (3),
+.BR malloc (3),
+.BR realloc (3),
+.BR string (3),
+.BR wcsdup (3)
diff --git a/man/man3/strdupa.3 b/man/man3/strdupa.3
new file mode 100644
index 000000000..2dd8f88c3
--- /dev/null
+++ b/man/man3/strdupa.3
@@ -0,0 +1 @@
+.so man3/strdup.3
diff --git a/man/man3/strerror.3 b/man/man3/strerror.3
new file mode 100644
index 000000000..8dc65dc67
--- /dev/null
+++ b/man/man3/strerror.3
@@ -0,0 +1,324 @@
+'\" t
+.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (C) 2005, 2014, 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:05:30 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Fri Feb 16 14:25:17 1996 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Sun Jul 21 20:55:44 1996 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Mon Oct 15 21:16:25 2001 by John Levon <moz@compsoc.man.ac.uk>
+.\" Modified Tue Oct 16 00:04:43 2001 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Fri Jun 20 03:04:30 2003 by Andries Brouwer <aeb@cwi.nl>
+.\" 2005-12-13, mtk, Substantial rewrite of strerror_r() description
+.\"         Addition of extra material on portability and standards.
+.\"
+.TH strerror 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strerror, strerrorname_np, strerrordesc_np, strerror_r, strerror_l \-
+return string describing error number
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strerror(int " errnum );
+.BI "const char *strerrorname_np(int " errnum );
+.BI "const char *strerrordesc_np(int " errnum );
+.P
+.BI "int strerror_r(int " errnum ", char " buf [. buflen "], size_t " buflen );
+               /* XSI-compliant */
+.P
+.BI "char *strerror_r(int " errnum ", char " buf [. buflen "], size_t " buflen );
+               /* GNU-specific */
+.P
+.BI "char *strerror_l(int " errnum ", locale_t " locale );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strerrorname_np (),
+.BR strerrordesc_np ():
+.nf
+    _GNU_SOURCE
+.fi
+.P
+.BR strerror_r ():
+.nf
+    The XSI-compliant version is provided if:
+        (_POSIX_C_SOURCE >= 200112L) && ! _GNU_SOURCE
+    Otherwise, the GNU-specific version is provided.
+.fi
+.SH DESCRIPTION
+The
+.BR strerror ()
+function returns a pointer to a string that describes the error
+code passed in the argument
+.IR errnum ,
+possibly using the
+.B LC_MESSAGES
+part of the current locale to select the appropriate language.
+(For example, if
+.I errnum
+is
+.BR EINVAL ,
+the returned description will be "Invalid argument".)
+This string must not be modified by the application,
+and the returned pointer will be invalidated on a subsequent call to
+.BR strerror ()
+or
+.BR strerror_l (),
+or if the thread that obtained the string exits.
+No other library function, including
+.BR perror (3),
+will modify this string.
+.P
+Like
+.BR strerror (),
+the
+.BR strerrordesc_np ()
+function returns a pointer to a string that describes the error
+code passed in the argument
+.IR errnum ,
+with the difference that the returned string is not translated
+according to the current locale.
+.P
+The
+.BR strerrorname_np ()
+function returns a pointer to a string containing the name of the error
+code passed in the argument
+.IR errnum .
+For example, given
+.B EPERM
+as an argument, this function returns a pointer to the string "EPERM".
+Given
+.B 0
+as an argument,
+this function returns a pointer to the string "0".
+.\"
+.SS strerror_r()
+.BR strerror_r ()
+is like
+.BR strerror (),
+but might use the supplied buffer
+.I buf
+instead of allocating one internally.
+This function is available in two versions:
+an XSI-compliant version specified in POSIX.1-2001
+(available since glibc 2.3.4, but not POSIX-compliant until glibc 2.13),
+and a GNU-specific version (available since glibc 2.0).
+The XSI-compliant version is provided with the feature test macros
+settings shown in the SYNOPSIS;
+otherwise the GNU-specific version is provided.
+If no feature test macros are explicitly defined,
+then (since glibc 2.4)
+.B _POSIX_C_SOURCE
+is defined by default with the value
+200112L, so that the XSI-compliant version of
+.BR strerror_r ()
+is provided by default.
+.P
+The XSI-compliant
+.BR strerror_r ()
+is preferred for portable applications.
+It returns the error string in the user-supplied buffer
+.I buf
+of length
+.IR buflen .
+.P
+The GNU-specific
+.BR strerror_r ()
+returns a pointer to a string containing the error message.
+This may be either a pointer to a string that the function stores in
+.IR buf ,
+or a pointer to some (immutable) static string
+(in which case
+.I buf
+is unused).
+If the function stores a string in
+.IR buf ,
+then at most
+.I buflen
+bytes are stored (the string may be truncated if
+.I buflen
+is too small and
+.I errnum
+is unknown).
+The string always includes a terminating null byte (\[aq]\e0\[aq]).
+.\"
+.SS strerror_l()
+.BR strerror_l ()
+is like
+.BR strerror (),
+but maps
+.I errnum
+to a locale-dependent error message in the locale specified by
+.IR locale .
+The behavior of
+.BR strerror_l ()
+is undefined if
+.I locale
+is the special locale object
+.B LC_GLOBAL_LOCALE
+or is not a valid locale object handle.
+.SH RETURN VALUE
+The
+.BR strerror (),
+.BR strerror_l (),
+and the GNU-specific
+.BR strerror_r ()
+functions return
+the appropriate error description string,
+or an "Unknown error nnn" message if the error number is unknown.
+.P
+On success,
+.BR strerrorname_np ()
+and
+.BR strerrordesc_np ()
+return the appropriate error description string.
+If
+.I errnum
+is an invalid error number, these functions return NULL.
+.P
+The XSI-compliant
+.BR strerror_r ()
+function returns 0 on success.
+On error,
+a (positive) error number is returned (since glibc 2.13),
+or \-1 is returned and
+.I errno
+is set to indicate the error (before glibc 2.13).
+.P
+POSIX.1-2001 and POSIX.1-2008 require that a successful call to
+.BR strerror ()
+or
+.BR strerror_l ()
+shall leave
+.I errno
+unchanged, and note that,
+since no function return value is reserved to indicate an error,
+an application that wishes to check for errors should initialize
+.I errno
+to zero before the call,
+and then check
+.I errno
+after the call.
+.SH ERRORS
+.TP
+.B EINVAL
+The value of
+.I errnum
+is not a valid error number.
+.TP
+.B ERANGE
+Insufficient storage was supplied to contain the error description string.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strerror ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe
+T}
+T{
+.na
+.nh
+.BR strerrorname_np (),
+.BR strerrordesc_np ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR strerror_r (),
+.BR strerror_l ()
+T}	Thread safety	MT-Safe
+.TE
+.P
+Before glibc 2.32,
+.BR strerror ()
+is not MT-Safe.
+.SH STANDARDS
+.TP
+.BR strerror ()
+C11, POSIX.1-2008.
+.TP
+.BR strerror_r ()
+.\" FIXME . for later review when Issue 8 is one day released...
+.\" A future POSIX.1 may remove strerror_r()
+.\" http://austingroupbugs.net/tag_view_page.php?tag_id=8
+.\" http://austingroupbugs.net/view.php?id=508
+.TQ
+.BR strerror_l ()
+POSIX.1-2008.
+.TP
+.BR strerrorname_np ()
+.TQ
+.BR strerrordesc_np ()
+GNU.
+.P
+POSIX.1-2001 permits
+.BR strerror ()
+to set
+.I errno
+if the call encounters an error, but does not specify what
+value should be returned as the function result in the event of an error.
+On some systems,
+.\" e.g., Solaris 8, HP-UX 11
+.BR strerror ()
+returns NULL if the error number is unknown.
+On other systems,
+.\" e.g., FreeBSD 5.4, Tru64 5.1B
+.BR strerror ()
+returns a string something like "Error nnn occurred" and sets
+.I errno
+to
+.B EINVAL
+if the error number is unknown.
+C99 and POSIX.1-2008 require the return value to be non-NULL.
+.SH HISTORY
+.TP
+.BR strerror ()
+POSIX.1-2001, C89.
+.TP
+.BR strerror_r ()
+POSIX.1-2001.
+.TP
+.BR strerror_l ()
+glibc 2.6.
+POSIX.1-2008.
+.TP
+.BR strerrorname_np ()
+.TQ
+.BR strerrordesc_np ()
+glibc 2.32.
+.SH NOTES
+.BR strerrorname_np ()
+and
+.BR strerrordesc_np ()
+are thread-safe and async-signal-safe.
+.SH SEE ALSO
+.BR err (3),
+.BR errno (3),
+.BR error (3),
+.BR perror (3),
+.BR strsignal (3),
+.BR locale (7),
+.BR signal-safety (7)
diff --git a/man/man3/strerror_l.3 b/man/man3/strerror_l.3
new file mode 100644
index 000000000..649dd6d91
--- /dev/null
+++ b/man/man3/strerror_l.3
@@ -0,0 +1 @@
+.so man3/strerror.3
diff --git a/man/man3/strerror_r.3 b/man/man3/strerror_r.3
new file mode 100644
index 000000000..649dd6d91
--- /dev/null
+++ b/man/man3/strerror_r.3
@@ -0,0 +1 @@
+.so man3/strerror.3
diff --git a/man/man3/strerrordesc_np.3 b/man/man3/strerrordesc_np.3
new file mode 100644
index 000000000..649dd6d91
--- /dev/null
+++ b/man/man3/strerrordesc_np.3
@@ -0,0 +1 @@
+.so man3/strerror.3
diff --git a/man/man3/strerrorname_np.3 b/man/man3/strerrorname_np.3
new file mode 100644
index 000000000..649dd6d91
--- /dev/null
+++ b/man/man3/strerrorname_np.3
@@ -0,0 +1 @@
+.so man3/strerror.3
diff --git a/man/man3/strfmon.3 b/man/man3/strfmon.3
new file mode 100644
index 000000000..a1e4d2153
--- /dev/null
+++ b/man/man3/strfmon.3
@@ -0,0 +1,209 @@
+'\" t
+.\" Copyright (c) 2000 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH strfmon 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strfmon, strfmon_l \- convert monetary value to a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <monetary.h>
+.P
+.BI "ssize_t strfmon(char " s "[restrict ." max "], size_t " max ,
+.BI "                const char *restrict " format ", ...);"
+.BI "ssize_t strfmon_l(char " s "[restrict ." max "], size_t " max ", \
+locale_t " locale ,
+.BI "                const char *restrict " format ", ...);"
+.fi
+.SH DESCRIPTION
+The
+.BR strfmon ()
+function formats the specified monetary amount
+according to the current locale
+and format specification
+.I format
+and places the
+result in the character array
+.I s
+of size
+.IR max .
+.P
+The
+.BR strfmon_l ()
+function performs the same task,
+but uses
+the locale specified by
+.IR locale .
+The behavior of
+.BR strfmon_l ()
+is undefined if
+.I locale
+is the special locale object
+.B LC_GLOBAL_LOCALE
+(see
+.BR duplocale (3))
+or is not a valid locale object handle.
+.P
+Ordinary characters in
+.I format
+are copied to
+.I s
+without conversion.
+Conversion specifiers are introduced by a \[aq]%\[aq]
+character.
+Immediately following it there can be zero or more
+of the following flags:
+.TP
+.BI = f
+The single-byte character
+.I f
+is used as the numeric fill character (to be used with
+a left precision, see below).
+When not specified, the space character is used.
+.TP
+.B \[ha]
+Do not use any grouping characters that might be defined
+for the current locale.
+By default, grouping is enabled.
+.TP
+.BR ( " or " +
+The ( flag indicates that negative amounts should be enclosed between
+parentheses.
+The + flag indicates that signs should be handled
+in the default way, that is, amounts are preceded by the locale's
+sign indication, for example, nothing for positive, "\-" for negative.
+.TP
+.B !
+Omit the currency symbol.
+.TP
+.B \-
+Left justify all fields.
+The default is right justification.
+.P
+Next, there may be a field width: a decimal digit string specifying
+a minimum field width in bytes.
+The default is 0.
+A result smaller than this width is padded with spaces
+(on the left, unless the left-justify flag was given).
+.P
+Next, there may be a left precision of the form "#" followed by
+a decimal digit string.
+If the number of digits left of the
+radix character is smaller than this, the representation is
+padded on the left with the numeric fill character.
+Grouping characters are not counted in this field width.
+.P
+Next, there may be a right precision of the form "." followed by
+a decimal digit string.
+The amount being formatted is rounded to
+the specified number of digits prior to formatting.
+The default is specified in the
+.I frac_digits
+and
+.I int_frac_digits
+items of the current locale.
+If the right precision is 0, no radix character is printed.
+(The radix character here is determined by
+.BR LC_MONETARY ,
+and may differ from that specified by
+.BR LC_NUMERIC .)
+.P
+Finally, the conversion specification must be ended with a
+conversion character.
+The three conversion characters are
+.TP
+.B %
+(In this case, the entire specification must be exactly "%%".)
+Put a \[aq]%\[aq] character in the result string.
+.TP
+.B i
+One argument of type
+.I double
+is converted using the locale's international currency format.
+.TP
+.B n
+One argument of type
+.I double
+is converted using the locale's national currency format.
+.SH RETURN VALUE
+The
+.BR strfmon ()
+function returns the number of characters placed
+in the array
+.IR s ,
+not including the terminating null byte,
+provided the string, including the terminating null byte, fits.
+Otherwise, it sets
+.I errno
+to
+.BR E2BIG ,
+returns \-1, and the contents of the array is undefined.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strfmon ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR strfmon_l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH EXAMPLES
+The call
+.P
+.in +4n
+.EX
+strfmon(buf, sizeof(buf), "[%\[ha]=*#6n] [%=*#6i]",
+        1234.567, 1234.567);
+.EE
+.in
+.P
+outputs
+.P
+.in +4n
+.EX
+[€ **1234,57] [EUR **1 234,57]
+.EE
+.in
+.P
+in the
+.I nl_NL
+locale.
+The
+.IR de_DE ,
+.IR de_CH ,
+.IR en_AU ,
+and
+.I en_GB
+locales yield
+.P
+.in +4n
+.EX
+[ **1234,57 €] [ **1.234,57 EUR]
+[ Fr. **1234.57] [ CHF **1\[aq]234.57]
+[ $**1234.57] [ AUD**1,234.57]
+[ £**1234.57] [ GBP**1,234.57]
+.EE
+.in
+.SH SEE ALSO
+.BR duplocale (3),
+.BR setlocale (3),
+.BR sprintf (3),
+.BR locale (7)
diff --git a/man/man3/strfmon_l.3 b/man/man3/strfmon_l.3
new file mode 100644
index 000000000..cdbc31041
--- /dev/null
+++ b/man/man3/strfmon_l.3
@@ -0,0 +1 @@
+.so man3/strfmon.3
diff --git a/man/man3/strfromd.3 b/man/man3/strfromd.3
new file mode 100644
index 000000000..dbcb8e78a
--- /dev/null
+++ b/man/man3/strfromd.3
@@ -0,0 +1,231 @@
+'\" t
+.\" Copyright (c) 2016, IBM Corporation.
+.\" Written by Wainer dos Santos Moschetta <wainersm@linux.vnet.ibm.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"   glibc 2.25 source code and manual.
+.\"   C99 standard document.
+.\"   ISO/IEC TS 18661-1 technical specification.
+.\"   snprintf and other man.3 pages.
+.\"
+.TH strfromd 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strfromd, strfromf, strfroml \- convert a floating-point value into
+a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int strfromd(char " str "[restrict ." n "], size_t " n ,
+.BI "             const char *restrict " format ", double " fp ");"
+.BI "int strfromf(char " str "[restrict ." n "], size_t " n ,
+.BI "             const char *restrict " format ", float "fp ");"
+.BI "int strfroml(char " str "[restrict ." n "], size_t " n ,
+.BI "             const char *restrict " format ", long double " fp ");"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strfromd (),
+.BR strfromf (),
+.BR strfroml ():
+.nf
+    __STDC_WANT_IEC_60559_BFP_EXT__
+.fi
+.SH DESCRIPTION
+These functions convert a floating-point value,
+.IR fp ,
+into a string of characters,
+.IR str ,
+with a configurable
+.I format
+string.
+At most
+.I n
+characters are stored into
+.IR str .
+.P
+The terminating null byte ('\e0') is written if and only if
+.I n
+is sufficiently large, otherwise the written string is truncated at
+.I n
+characters.
+.P
+The
+.BR strfromd (),
+.BR strfromf (),
+and
+.BR strfroml ()
+functions are equivalent to
+.P
+.in +4n
+.EX
+snprintf(str, n, format, fp);
+.EE
+.in
+.P
+except for the
+.I format
+string.
+.SS Format of the format string
+The
+.I format
+string must start with the character \[aq]%\[aq].
+This is followed by an optional precision which starts with the period
+character (.), followed by an optional decimal integer.
+If no integer is specified after the period character,
+a precision of zero is used.
+Finally, the format string should have one of the conversion specifiers
+.BR a ,
+.BR A ,
+.BR e ,
+.BR E ,
+.BR f ,
+.BR F ,
+.BR g ,
+or
+.BR G .
+.P
+The conversion specifier is applied based on the floating-point type
+indicated by the function suffix.
+Therefore, unlike
+.BR snprintf (),
+the format string does not have a length modifier character.
+See
+.BR snprintf (3)
+for a detailed description of these conversion specifiers.
+.P
+The implementation conforms to the C99 standard on conversion of NaN and
+infinity values:
+.P
+.RS
+If
+.I fp
+is a NaN, +NaN, or \-NaN, and
+.B f
+(or
+.BR a ,
+.BR e ,
+.BR g )
+is the conversion specifier, the conversion is to "nan", "nan", or "\-nan",
+respectively.
+If
+.B F
+(or
+.BR A ,
+.BR E ,
+.BR G )
+is the conversion specifier, the conversion is to "NAN" or "\-NAN".
+.P
+Likewise if
+.I fp
+is infinity, it is converted to [\-]inf or [\-]INF.
+.RE
+.P
+A malformed
+.I format
+string results in undefined behavior.
+.SH RETURN VALUE
+The
+.BR strfromd (),
+.BR strfromf (),
+and
+.BR strfroml ()
+functions return the number of characters that would have been written in
+.I str
+if
+.I n
+had enough space,
+not counting the terminating null byte.
+Thus, a return value of
+.I n
+or greater means that the output was truncated.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7)
+and the
+.B POSIX Safety Concepts
+section in GNU C Library manual.
+.P
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strfromd (),
+.BR strfromf (),
+.BR strfroml ()
+T}	Thread safety	MT-Safe locale
+\^	Async-signal safety	AS-Unsafe heap
+\^	Async-cancel safety	AC-Unsafe mem
+.TE
+.P
+Note: these attributes are preliminary.
+.SH STANDARDS
+ISO/IEC TS 18661-1.
+.SH VERSIONS
+.TP
+.BR strfromd ()
+.TQ
+.BR strfromf ()
+.TQ
+.BR strfroml ()
+glibc 2.25.
+.SH NOTES
+These functions take account of the
+.B LC_NUMERIC
+category of the current locale.
+.SH EXAMPLES
+To convert the value 12.1 as a float type to a string using decimal
+notation, resulting in "12.100000":
+.P
+.in +4n
+.EX
+#define __STDC_WANT_IEC_60559_BFP_EXT__
+#include <stdlib.h>
+int ssize = 10;
+char s[ssize];
+strfromf(s, ssize, "%f", 12.1);
+.EE
+.in
+.P
+To convert the value 12.3456 as a float type to a string using
+decimal notation with two digits of precision, resulting in "12.35":
+.P
+.in +4n
+.EX
+#define __STDC_WANT_IEC_60559_BFP_EXT__
+#include <stdlib.h>
+int ssize = 10;
+char s[ssize];
+strfromf(s, ssize, "%.2f", 12.3456);
+.EE
+.in
+.P
+To convert the value 12.345e19 as a double type to a string using
+scientific notation with zero digits of precision, resulting in "1E+20":
+.P
+.in +4n
+.EX
+#define __STDC_WANT_IEC_60559_BFP_EXT__
+#include <stdlib.h>
+int ssize = 10;
+char s[ssize];
+strfromd(s, ssize, "%.E", 12.345e19);
+.EE
+.in
+.SH SEE ALSO
+.BR atof (3),
+.BR snprintf (3),
+.BR strtod (3)
diff --git a/man/man3/strfromf.3 b/man/man3/strfromf.3
new file mode 100644
index 000000000..d20099dc8
--- /dev/null
+++ b/man/man3/strfromf.3
@@ -0,0 +1 @@
+.so man3/strfromd.3
diff --git a/man/man3/strfroml.3 b/man/man3/strfroml.3
new file mode 100644
index 000000000..d20099dc8
--- /dev/null
+++ b/man/man3/strfroml.3
@@ -0,0 +1 @@
+.so man3/strfromd.3
diff --git a/man/man3/strfry.3 b/man/man3/strfry.3
new file mode 100644
index 000000000..e04d2be31
--- /dev/null
+++ b/man/man3/strfry.3
@@ -0,0 +1,55 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:39:43 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strfry 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strfry \- randomize a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <string.h>
+.P
+.BI "char *strfry(char *" string );
+.fi
+.SH DESCRIPTION
+The
+.BR strfry ()
+function randomizes the contents of
+.I string
+by randomly swapping characters in the string.
+The result is an anagram of
+.IR string .
+.SH RETURN VALUE
+The
+.BR strfry ()
+functions returns a pointer to the randomized
+string.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strfry ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+GNU.
+.SH SEE ALSO
+.BR memfrob (3),
+.BR string (3)
diff --git a/man/man3/strftime.3 b/man/man3/strftime.3
new file mode 100644
index 000000000..13121963f
--- /dev/null
+++ b/man/man3/strftime.3
@@ -0,0 +1,777 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\"     GNU texinfo documentation on glibc date/time functions.
+.\" Modified Sat Jul 24 18:03:44 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Applied fix by Wolfgang Franke, aeb, 961011
+.\" Corrected return value, aeb, 970307
+.\" Added Single UNIX Spec conversions and %z, aeb/esr, 990329.
+.\" 2005-11-22 mtk, added glibc Notes covering optional 'flag' and
+.\"           'width' components of conversion specifications.
+.\"
+.TH strftime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strftime \- format date and time
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "size_t strftime(char " s "[restrict ." max "], size_t " max ,
+.BI "                const char *restrict " format ,
+.BI "                const struct tm *restrict " tm );
+.P
+.BI "size_t strftime_l(char " s "[restrict ." max "], size_t " max ,
+.BI "                const char *restrict " format ,
+.BI "                const struct tm *restrict " tm ,
+.BI "                locale_t " locale );
+.fi
+.SH DESCRIPTION
+The
+.BR strftime ()
+function formats the broken-down time
+.I tm
+according to the format specification
+.I format
+and places the
+result in the character array
+.I s
+of size
+.IR max .
+The broken-down time structure
+.I tm
+is defined in
+.IR <time.h> .
+See also
+.BR ctime (3).
+.\" FIXME . POSIX says: Local timezone information is used as though
+.\" strftime() called tzset().  But this doesn't appear to be the case
+.P
+The format specification is a null-terminated string and may contain
+special character sequences called
+.IR "conversion specifications",
+each of which is introduced by a \[aq]%\[aq] character and terminated by
+some other character known as a
+.IR "conversion specifier character".
+All other character sequences are
+.IR "ordinary character sequences".
+.P
+The characters of ordinary character sequences (including the null byte)
+are copied verbatim from
+.I format
+to
+.IR s .
+However, the characters
+of conversion specifications are replaced as shown in the list below.
+In this list, the field(s) employed from the
+.I tm
+structure are also shown.
+.TP
+.B %a
+The abbreviated name of the day of the week according to the current locale.
+(Calculated from
+.IR tm_wday .)
+(The specific names used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.BR ABDAY_ { 1 \[en] 7 }
+as an argument.)
+.TP
+.B %A
+The full name of the day of the week according to the current locale.
+(Calculated from
+.IR tm_wday .)
+(The specific names used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.BR DAY_ { 1 \[en] 7 }
+as an argument.)
+.TP
+.B %b
+The abbreviated month name according to the current locale.
+(Calculated from
+.IR tm_mon .)
+(The specific names used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.BR ABMON_ { 1 \[en] 12 }
+as an argument.)
+.TP
+.B %B
+The full month name according to the current locale.
+(Calculated from
+.IR tm_mon .)
+(The specific names used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.BR MON_ { 1 \[en] 12 }
+as an argument.)
+.TP
+.B %c
+The preferred date and time representation for the current locale.
+(The specific format used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.B D_T_FMT
+as an argument for the
+.B %c
+conversion specification, and with
+.B ERA_D_T_FMT
+for the
+.B %Ec
+conversion specification.)
+(In the POSIX locale this is equivalent to
+.BR "%a %b %e %H:%M:%S %Y" .)
+.TP
+.B %C
+The century number (year/100) as a 2-digit integer. (SU)
+(The
+.B %EC
+conversion specification corresponds to the name of the era.)
+(Calculated from
+.IR tm_year .)
+.TP
+.B %d
+The day of the month as a decimal number (range 01 to 31).
+(Calculated from
+.IR tm_mday .)
+.TP
+.B %D
+Equivalent to
+.BR %m/%d/%y .
+(Yecch\[em]for Americans only.
+Americans should note that in other countries
+.B %d/%m/%y
+is rather common.
+This means that in international context this format is
+ambiguous and should not be used.) (SU)
+.TP
+.B %e
+Like
+.BR %d ,
+the day of the month as a decimal number, but a leading
+zero is replaced by a space. (SU)
+(Calculated from
+.IR tm_mday .)
+.TP
+.B %E
+Modifier: use alternative ("era-based") format, see below. (SU)
+.TP
+.B %F
+Equivalent to
+.B %Y\-%m\-%d
+(the ISO\~8601 date format). (C99)
+.TP
+.B %G
+The ISO\~8601 week-based year (see NOTES) with century as a decimal number.
+The 4-digit year corresponding to the ISO week number (see
+.BR %V ).
+This has the same format and value as
+.BR %Y ,
+except that if the ISO week number belongs to the previous or next year,
+that year is used instead. (TZ)
+(Calculated from
+.IR tm_year ,
+.IR tm_yday ,
+and
+.IR tm_wday .)
+.TP
+.B %g
+Like
+.BR %G ,
+but without century, that is, with a 2-digit year (00\[en]99). (TZ)
+(Calculated from
+.IR tm_year ,
+.IR tm_yday ,
+and
+.IR tm_wday .)
+.TP
+.B %h
+Equivalent to
+.BR %b .
+(SU)
+.TP
+.B %H
+The hour as a decimal number using a 24-hour clock (range 00 to 23).
+(Calculated from
+.IR tm_hour .)
+.TP
+.B %I
+The hour as a decimal number using a 12-hour clock (range 01 to 12).
+(Calculated from
+.IR tm_hour .)
+.TP
+.B %j
+The day of the year as a decimal number (range 001 to 366).
+(Calculated from
+.IR tm_yday .)
+.TP
+.B %k
+The hour (24-hour clock) as a decimal number (range 0 to 23);
+single digits are preceded by a blank.
+(See also
+.BR %H .)
+(Calculated from
+.IR tm_hour .)
+(TZ)
+.TP
+.B %l
+The hour (12-hour clock) as a decimal number (range 1 to 12);
+single digits are preceded by a blank.
+(See also
+.BR %I .)
+(Calculated from
+.IR tm_hour .)
+(TZ)
+.TP
+.B %m
+The month as a decimal number (range 01 to 12).
+(Calculated from
+.IR tm_mon .)
+.TP
+.B %M
+The minute as a decimal number (range 00 to 59).
+(Calculated from
+.IR tm_min .)
+.TP
+.B %n
+A newline character. (SU)
+.TP
+.B %O
+Modifier: use alternative numeric symbols, see below. (SU)
+.TP
+.B %p
+Either "AM" or "PM" according to the given time value, or the
+corresponding strings for the current locale.
+Noon is treated as "PM" and midnight as "AM".
+(Calculated from
+.IR tm_hour .)
+(The specific string representations used for "AM" and "PM"
+in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.BR AM_STR " and " PM_STR ,
+respectively.)
+.TP
+.B %P
+Like
+.B %p
+but in lowercase: "am" or "pm" or a corresponding
+string for the current locale.
+(Calculated from
+.IR tm_hour .)
+(GNU)
+.TP
+.B %r
+The time in a.m. or p.m. notation.
+(SU)
+(The specific format used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.B T_FMT_AMPM
+as an argument.)
+(In the POSIX locale this is equivalent to
+.BR "%I:%M:%S %p" .)
+.TP
+.B %R
+The time in 24-hour notation
+.RB ( %H:%M ).
+(SU)
+For a version including the seconds, see
+.B %T
+below.
+.TP
+.B %s
+The number of seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC). (TZ)
+(Calculated from
+.IR mktime(tm) .)
+.TP
+.B %S
+The second as a decimal number (range 00 to 60).
+(The range is up to 60 to allow for occasional leap seconds.)
+(Calculated from
+.IR tm_sec .)
+.TP
+.B %t
+A tab character. (SU)
+.TP
+.B %T
+The time in 24-hour notation
+.RB ( %H:%M:%S ).
+(SU)
+.TP
+.B %u
+The day of the week as a decimal, range 1 to 7, Monday being 1.
+See also
+.BR %w .
+(Calculated from
+.IR tm_wday .)
+(SU)
+.TP
+.B %U
+The week number of the current year as a decimal number,
+range 00 to 53, starting with the first Sunday as the first day
+of week 01.
+See also
+.B %V
+and
+.BR %W .
+(Calculated from
+.I tm_yday
+and
+.IR tm_wday .)
+.TP
+.B %V
+The ISO\~8601 week number (see NOTES) of the current year as a decimal number,
+range 01 to 53, where week 1 is the first week that has at least
+4 days in the new year.
+See also
+.B %U
+and
+.BR %W .
+(Calculated from
+.IR tm_year ,
+.IR tm_yday ,
+and
+.IR tm_wday .)
+(SU)
+.TP
+.B %w
+The day of the week as a decimal, range 0 to 6, Sunday being 0.
+See also
+.BR %u .
+(Calculated from
+.IR tm_wday .)
+.TP
+.B %W
+The week number of the current year as a decimal number,
+range 00 to 53, starting with the first Monday as the first day of week 01.
+(Calculated from
+.I tm_yday
+and
+.IR tm_wday .)
+.TP
+.B %x
+The preferred date representation for the current locale without the time.
+(The specific format used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.B D_FMT
+as an argument for the
+.B %x
+conversion specification, and with
+.B ERA_D_FMT
+for the
+.B %Ex
+conversion specification.)
+(In the POSIX locale this is equivalent to
+.BR %m/%d/%y .)
+.TP
+.B %X
+The preferred time representation for the current locale without the date.
+(The specific format used in the current locale can be obtained by calling
+.BR nl_langinfo (3)
+with
+.B T_FMT
+as an argument for the
+.B %X
+conversion specification, and with
+.B ERA_T_FMT
+for the
+.B %EX
+conversion specification.)
+(In the POSIX locale this is equivalent to
+.BR %H:%M:%S .)
+.TP
+.B %y
+The year as a decimal number without a century (range 00 to 99).
+(The
+.B %Ey
+conversion specification corresponds to the year since the beginning of the era
+denoted by the
+.B %EC
+conversion specification.)
+(Calculated from
+.IR tm_year )
+.TP
+.B %Y
+The year as a decimal number including the century.
+(The
+.B %EY
+conversion specification corresponds to
+the full alternative year representation.)
+(Calculated from
+.IR tm_year )
+.TP
+.B %z
+The
+.I +hhmm
+or
+.I \-hhmm
+numeric timezone (that is, the hour and minute offset from UTC). (SU)
+.TP
+.B %Z
+The timezone name or abbreviation.
+.TP
+.B %+
+.\" Nov 05 -- Not in Linux/glibc, but is in some BSDs (according to
+.\" their man pages)
+The date and time in
+.BR date (1)
+format. (TZ)
+(Not supported in glibc2.)
+.TP
+.B %%
+A literal \[aq]%\[aq] character.
+.P
+Some conversion specifications can be modified by preceding the
+conversion specifier character by the
+.B E
+or
+.B O
+.I modifier
+to indicate that an alternative format should be used.
+If the alternative format or specification does not exist for
+the current locale, the behavior will be as if the unmodified
+conversion specification were used. (SU)
+The Single UNIX Specification mentions
+.BR %Ec ,
+.BR %EC ,
+.BR %Ex ,
+.BR %EX ,
+.BR %Ey ,
+.BR %EY ,
+.BR %Od ,
+.BR %Oe ,
+.BR %OH ,
+.BR %OI ,
+.BR %Om ,
+.BR %OM ,
+.BR %OS ,
+.BR %Ou ,
+.BR %OU ,
+.BR %OV ,
+.BR %Ow ,
+.BR %OW ,
+.BR %Oy ,
+where the effect of the
+.B O
+modifier is to use
+alternative numeric symbols (say, roman numerals), and that of the
+.B E
+modifier is to use a locale-dependent alternative representation.
+The rules governing date representation with the
+.B E
+modifier can be obtained by supplying
+.B ERA
+as an argument to a
+.BR nl_langinfo (3).
+One example of such alternative forms is the Japanese era calendar scheme in the
+.B ja_JP
+glibc locale.
+.P
+.BR strftime_l ()
+is equivalent to
+.BR strftime (),
+except it uses the specified
+.I locale
+instead of the current locale.
+The behaviour is undefined if
+.I locale
+is invalid or
+.BR LC_GLOBAL_LOCALE .
+.SH RETURN VALUE
+Provided that the result string,
+including the terminating null byte, does not exceed
+.I max
+bytes,
+.BR strftime ()
+returns the number of bytes (excluding the terminating null byte)
+placed in the array
+.IR s .
+If the length of the result string (including the terminating null byte)
+would exceed
+.I max
+bytes, then
+.BR strftime ()
+returns 0, and the contents of the array are undefined.
+.\" (This behavior applies since at least libc 4.4.4;
+.\" very old versions of libc, such as libc 4.4.1,
+.\" would return
+.\" .I max
+.\" if the array was too small.)
+.P
+Note that the return value 0 does not necessarily indicate an error.
+For example, in many locales
+.B %p
+yields an empty string.
+An empty
+.I format
+string will likewise yield an empty string.
+.SH ENVIRONMENT
+The environment variables
+.B TZ
+and
+.B LC_TIME
+are used.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strftime (),
+.BR strftime_l ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+.TP
+.BR strftime ()
+C11, POSIX.1-2008.
+.TP
+.BR strftime_l ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR strftime ()
+SVr4, C89.
+.\" FIXME strftime() is in POSIX.1-2001 and POSIX.1-2008, but the details
+.\" in the standards changed across versions. Investigate and
+.\" write up.
+.TP
+.BR strftime_l ()
+POSIX.1-2008.
+.P
+There are strict inclusions between the set of conversions
+given in ANSI C (unmarked), those given in the Single UNIX Specification
+(marked SU), those given in Olson's timezone package (marked TZ),
+and those given in glibc (marked GNU), except that
+.B %+
+is not supported in glibc2.
+On the other hand glibc2 has several more extensions.
+POSIX.1 only refers to ANSI C; POSIX.2 describes under
+.BR date (1)
+several extensions that could apply to
+.BR strftime ()
+as well.
+The
+.B %F
+conversion is in C99 and POSIX.1-2001.
+.P
+In SUSv2, the
+.B %S
+specifier allowed a range of 00 to 61,
+to allow for the theoretical possibility of a minute that
+included a double leap second
+(there never has been such a minute).
+.SH NOTES
+.SS ISO\~8601 week dates
+.BR %G ,
+.BR %g ,
+and
+.B %V
+yield values calculated from the week-based year defined by the
+ISO\~8601 standard.
+In this system, weeks start on a Monday, and are numbered from 01,
+for the first week, up to 52 or 53, for the last week.
+Week 1 is the first week where four or more days fall within the
+new year (or, synonymously, week 01 is:
+the first week of the year that contains a Thursday;
+or, the week that has 4 January in it).
+When three or fewer days of the first calendar week of the new year fall
+within that year,
+then the ISO\~8601 week-based system counts those days as part of week 52
+or 53 of the preceding year.
+For example, 1 January 2010 is a Friday,
+meaning that just three days of that calendar week fall in 2010.
+Thus, the ISO\~8601 week-based system considers these days to be part of
+week 53
+.RB ( %V )
+of the year 2009
+.RB ( %G );
+week 01 of ISO\~8601 year 2010 starts on Monday, 4 January 2010.
+Similarly, the first two days of January 2011 are considered to be part
+of week 52 of the year 2010.
+.SS glibc notes
+glibc provides some extensions for conversion specifications.
+(These extensions are not specified in POSIX.1-2001, but a few other
+systems provide similar features.)
+.\" HP-UX and Tru64 also have features like this.
+Between the \[aq]%\[aq] character and the conversion specifier character,
+an optional
+.I flag
+and field
+.I width
+may be specified.
+(These precede the
+.B E
+or
+.B O
+modifiers, if present.)
+.P
+The following flag characters are permitted:
+.TP
+.B _
+(underscore)
+Pad a numeric result string with spaces.
+.TP
+.B \-
+(dash)
+Do not pad a numeric result string.
+.TP
+.B 0
+Pad a numeric result string with zeros even if the conversion
+specifier character uses space-padding by default.
+.TP
+.B \[ha]
+Convert alphabetic characters in result string to uppercase.
+.TP
+.B #
+Swap the case of the result string.
+(This flag works only with certain conversion specifier characters,
+and of these, it is only really useful with
+.BR %Z .)
+.P
+An optional decimal width specifier may follow the (possibly absent) flag.
+If the natural size of the field is smaller than this width,
+then the result string is padded (on the left) to the specified width.
+.SH BUGS
+If the output string would exceed
+.I max
+bytes,
+.I errno
+is
+.I not
+set.
+This makes it impossible to distinguish this error case from cases where the
+.I format
+string legitimately produces a zero-length output string.
+POSIX.1-2001
+does
+.I not
+specify any
+.I errno
+settings for
+.BR strftime ().
+.P
+Some buggy versions of
+.BR gcc (1)
+complain about the use of
+.BR %c :
+.IR "warning: \`%c\[aq] yields only last 2 digits of year in some locales" .
+Of course programmers are encouraged to use
+.BR %c ,
+as it gives the preferred date and time representation.
+One meets all kinds of strange obfuscations
+to circumvent this
+.BR gcc (1)
+problem.
+A relatively clean one is to add an
+intermediate function
+.P
+.in +4n
+.EX
+size_t
+my_strftime(char *s, size_t max, const char *fmt,
+            const struct tm *tm)
+{
+    return strftime(s, max, fmt, tm);
+}
+.EE
+.in
+.P
+Nowadays,
+.BR gcc (1)
+provides the
+.I \-Wno\-format\-y2k
+option to prevent the warning,
+so that the above workaround is no longer required.
+.SH EXAMPLES
+.B RFC\~2822-compliant date format
+(with an English locale for %a and %b)
+.P
+.in +4n
+.EX
+"%a,\ %d\ %b\ %Y\ %T\ %z"
+.EE
+.in
+.P
+.B RFC\~822-compliant date format
+(with an English locale for %a and %b)
+.P
+.in +4n
+.EX
+"%a,\ %d\ %b\ %y\ %T\ %z"
+.EE
+.in
+.SS Example program
+The program below can be used to experiment with
+.BR strftime ().
+.P
+Some examples of the result string produced by the glibc implementation of
+.BR strftime ()
+are as follows:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \[aq]%m\[aq]"
+Result string is "11"
+.RB "$" " ./a.out \[aq]%5m\[aq]"
+Result string is "00011"
+.RB "$" " ./a.out \[aq]%_5m\[aq]"
+Result string is "   11"
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (strftime.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    char outstr[200];
+    time_t t;
+    struct tm *tmp;
+\&
+    t = time(NULL);
+    tmp = localtime(&t);
+    if (tmp == NULL) {
+        perror("localtime");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (strftime(outstr, sizeof(outstr), argv[1], tmp) == 0) {
+        fprintf(stderr, "strftime returned 0");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Result string is \e"%s\e"\en", outstr);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR date (1),
+.BR time (2),
+.BR ctime (3),
+.BR nl_langinfo (3),
+.BR setlocale (3),
+.BR sprintf (3),
+.BR strptime (3)
diff --git a/man/man3/strftime_l.3 b/man/man3/strftime_l.3
new file mode 100644
index 000000000..02e797a23
--- /dev/null
+++ b/man/man3/strftime_l.3
@@ -0,0 +1 @@
+.so man3/strftime.3
diff --git a/man/man3/string.3 b/man/man3/string.3
new file mode 100644
index 000000000..08b050b17
--- /dev/null
+++ b/man/man3/string.3
@@ -0,0 +1,217 @@
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:54:31 1993, Rik Faith (faith@cs.unc.edu)
+.TH string 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+stpcpy, strcasecmp, strcat, strchr, strcmp, strcoll, strcpy, strcspn,
+strdup, strfry, strlen, strncat, strncmp, strncpy, strncasecmp, strpbrk,
+strrchr, strsep, strspn, strstr, strtok, strxfrm, index, rindex
+\- string operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.B #include <strings.h>
+.TP
+.BI "int strcasecmp(const char *" s1 ", const char *" s2 );
+Compare the strings
+.I s1
+and
+.I s2
+ignoring case.
+.TP
+.BI "int strncasecmp(const char " s1 [. n "], const char " s2 [. n "], \
+size_t " n );
+Compare the first
+.I n
+bytes of the strings
+.I s1
+and
+.I s2
+ignoring case.
+.TP
+.BI "char *index(const char *" s ", int " c );
+Identical to
+.BR strchr (3).
+.TP
+.BI "char *rindex(const char *" s ", int " c );
+Identical to
+.BR strrchr (3).
+.TP
+.B #include <string.h>
+.TP
+.BI "char *stpcpy(char *restrict " dest ", const char *restrict " src );
+Copy a string from
+.I src
+to
+.IR dest ,
+returning a pointer to the end of the resulting string at
+.IR dest .
+.TP
+.BI "char *strcat(char *restrict " dest ", const char *restrict " src );
+Append the string
+.I src
+to the string
+.IR dest ,
+returning a pointer
+.IR dest .
+.TP
+.BI "char *strchr(const char *" s ", int " c );
+Return a pointer to the first occurrence of the character
+.I c
+in the string
+.IR s .
+.TP
+.BI "int strcmp(const char *" s1 ", const char *" s2 );
+Compare the strings
+.I s1
+with
+.IR s2 .
+.TP
+.BI "int strcoll(const char *" s1 ", const char *" s2 );
+Compare the strings
+.I s1
+with
+.I s2
+using the current locale.
+.TP
+.BI "char *strcpy(char *restrict " dest ", const char *restrict " src );
+Copy the string
+.I src
+to
+.IR dest ,
+returning a pointer to the start of
+.IR dest .
+.TP
+.BI "size_t strcspn(const char *" s ", const char *" reject );
+Calculate the length of the initial segment of the string
+.I s
+which does not contain any of bytes in the string
+.IR reject ,
+.TP
+.BI "char *strdup(const char *" s );
+Return a duplicate of the string
+.I s
+in memory allocated using
+.BR malloc (3).
+.TP
+.BI "char *strfry(char *" string );
+Randomly swap the characters in
+.IR string .
+.TP
+.BI "size_t strlen(const char *" s );
+Return the length of the string
+.IR s .
+.TP
+.nf
+.BI "char *strncat(char " dest "[restrict strlen(." dest ") + ." n " + 1],"
+.BI "       const char " src "[restrict ." n ],
+.BI "       size_t " n );
+.fi
+Append at most
+.I n
+bytes from the unterminated string
+.I src
+to the string
+.IR dest ,
+returning a pointer to
+.IR dest .
+.TP
+.BI "int strncmp(const char " s1 [. n "], const char " s2 [. n "], size_t " n );
+Compare at most
+.I n
+bytes of the strings
+.I s1
+and
+.IR s2 .
+.TP
+.BI "char *strpbrk(const char *" s ", const char *" accept );
+Return a pointer to the first occurrence in the string
+.I s
+of one of the bytes in the string
+.IR accept .
+.TP
+.BI "char *strrchr(const char *" s ", int " c );
+Return a pointer to the last occurrence of the character
+.I c
+in the string
+.IR s .
+.TP
+.BI "char *strsep(char **restrict " stringp ", const char *restrict " delim );
+Extract the initial token in
+.I stringp
+that is delimited by one of the bytes in
+.IR delim .
+.TP
+.BI "size_t strspn(const char *" s ", const char *" accept );
+Calculate the length of the starting segment in the string
+.I s
+that consists entirely of bytes in
+.IR accept .
+.TP
+.BI "char *strstr(const char *" haystack ", const char *" needle );
+Find the first occurrence of the substring
+.I needle
+in the string
+.IR haystack ,
+returning a pointer to the found substring.
+.TP
+.BI "char *strtok(char *restrict " s ", const char *restrict " delim );
+Extract tokens from the string
+.I s
+that are delimited by one of the bytes in
+.IR delim .
+.TP
+.nf
+.BI "size_t strxfrm(char " dest "[restrict ." n "], \
+const char " src "[restrict ." n ],
+.BI "        size_t " n );
+.fi
+Transforms
+.I src
+to the current locale and copies the first
+.I n
+bytes to
+.IR dest .
+.TP
+.nf
+.BI "char *strncpy(char " dest "[restrict ." n "], \
+const char " src "[restrict ." n ],
+.BI "       size_t " n );
+.fi
+Fill a fixed-size buffer with leading non-null bytes from a source array,
+padding with null bytes as needed.
+.SH DESCRIPTION
+The string functions perform operations on null-terminated
+strings.
+See the individual man pages for descriptions of each function.
+.SH SEE ALSO
+.BR bstring (3),
+.BR stpcpy (3),
+.BR strcasecmp (3),
+.BR strcat (3),
+.BR strchr (3),
+.BR strcmp (3),
+.BR strcoll (3),
+.BR strcpy (3),
+.BR strcspn (3),
+.BR strdup (3),
+.BR strfry (3),
+.BR strlen (3),
+.BR strncasecmp (3),
+.BR strncat (3),
+.BR strncmp (3),
+.BR strncpy (3),
+.BR strpbrk (3),
+.BR strrchr (3),
+.BR strsep (3),
+.BR strspn (3),
+.BR strstr (3),
+.BR strtok (3),
+.BR strxfrm (3)
diff --git a/man/man3/strlen.3 b/man/man3/strlen.3
new file mode 100644
index 000000000..6d759bd78
--- /dev/null
+++ b/man/man3/strlen.3
@@ -0,0 +1,61 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:02:26 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strlen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strlen \- calculate the length of a string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "size_t strlen(const char *" s );
+.fi
+.SH DESCRIPTION
+The
+.BR strlen ()
+function calculates the length of the string pointed to by
+.IR s ,
+excluding the terminating null byte (\[aq]\e0\[aq]).
+.SH RETURN VALUE
+The
+.BR strlen ()
+function returns the number of bytes in the string pointed to by
+.IR s .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strlen ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH NOTES
+In cases where the input buffer may not contain
+a terminating null byte,
+.BR strnlen (3)
+should be used instead.
+.SH SEE ALSO
+.BR string (3),
+.BR strnlen (3),
+.BR wcslen (3),
+.BR wcsnlen (3)
diff --git a/man/man3/strncasecmp.3 b/man/man3/strncasecmp.3
new file mode 100644
index 000000000..fd3b6715e
--- /dev/null
+++ b/man/man3/strncasecmp.3
@@ -0,0 +1 @@
+.so man3/strcasecmp.3
diff --git a/man/man3/strncat.3 b/man/man3/strncat.3
new file mode 100644
index 000000000..a1e736e93
--- /dev/null
+++ b/man/man3/strncat.3
@@ -0,0 +1,132 @@
+'\" t
+.\" Copyright 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH strncat 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strncat
+\-
+append non-null bytes from a source array to a string,
+and null-terminate the result
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strncat(char *restrict " dst ", const char " src "[restrict ." ssize ],
+.BI "              size_t " ssize );
+.fi
+.SH DESCRIPTION
+This function appends at most
+.I ssize
+non-null bytes from the array pointed to by
+.IR src ,
+followed by a null character,
+to the end of the string pointed to by
+.IR dst .
+.I dst
+must point to a string contained in a buffer that is large enough,
+that is, the buffer size must be at least
+.IR "strlen(dst) + strnlen(src, ssize) + 1" .
+.P
+An implementation of this function might be:
+.P
+.in +4n
+.EX
+char *
+strncat(char *restrict dst, const char *restrict src, size_t ssize)
+{
+    #define strnul(s)  (s + strlen(s))
+\&
+    stpcpy(mempcpy(strnul(dst), src, strnlen(src, ssize)), "");
+    return dst;
+}
+.EE
+.in
+.SH RETURN VALUE
+.BR strncat ()
+returns
+.IR dst .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strncat ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH CAVEATS
+The name of this function is confusing;
+it has no relation to
+.BR strncpy (3).
+.P
+If the destination buffer does not already contain a string,
+or is not large enough,
+the behavior is undefined.
+See
+.B _FORTIFY_SOURCE
+in
+.BR feature_test_macros (7).
+.SH BUGS
+This function can be very inefficient.
+Read about
+.UR https://www.joelonsoftware.com/\:2001/12/11/\:back\-to\-basics/
+Shlemiel the painter
+.UE .
+.SH EXAMPLES
+.\" SRC BEGIN (strncat.c)
+.EX
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define nitems(arr)  (sizeof((arr)) / sizeof((arr)[0]))
+\&
+int
+main(void)
+{
+    size_t  n;
+\&
+    // Null-padded fixed-size character sequences
+    char    pre[4] = "pre.";
+    char    new_post[50] = ".foo.bar";
+\&
+    // Strings
+    char    post[] = ".post";
+    char    src[] = "some_long_body.post";
+    char    *dest;
+\&
+    n = nitems(pre) + strlen(src) \- strlen(post) + nitems(new_post) + 1;
+    dest = malloc(sizeof(*dest) * n);
+    if (dest == NULL)
+        err(EXIT_FAILURE, "malloc()");
+\&
+    dest[0] = \[aq]\e0\[aq];  // There's no 'cpy' function to this 'cat'.
+    strncat(dest, pre, nitems(pre));
+    strncat(dest, src, strlen(src) \- strlen(post));
+    strncat(dest, new_post, nitems(new_post));
+\&
+    puts(dest);  // "pre.some_long_body.foo.bar"
+    free(dest);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.in
+.SH SEE ALSO
+.BR string (3),
+.BR string_copying (7)
diff --git a/man/man3/strncmp.3 b/man/man3/strncmp.3
new file mode 100644
index 000000000..1007f4346
--- /dev/null
+++ b/man/man3/strncmp.3
@@ -0,0 +1 @@
+.so man3/strcmp.3
diff --git a/man/man3/strncpy.3 b/man/man3/strncpy.3
new file mode 100644
index 000000000..4710b0201
--- /dev/null
+++ b/man/man3/strncpy.3
@@ -0,0 +1 @@
+.so man3/stpncpy.3
diff --git a/man/man3/strndup.3 b/man/man3/strndup.3
new file mode 100644
index 000000000..2dd8f88c3
--- /dev/null
+++ b/man/man3/strndup.3
@@ -0,0 +1 @@
+.so man3/strdup.3
diff --git a/man/man3/strndupa.3 b/man/man3/strndupa.3
new file mode 100644
index 000000000..2dd8f88c3
--- /dev/null
+++ b/man/man3/strndupa.3
@@ -0,0 +1 @@
+.so man3/strdup.3
diff --git a/man/man3/strnlen.3 b/man/man3/strnlen.3
new file mode 100644
index 000000000..098d44ba6
--- /dev/null
+++ b/man/man3/strnlen.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"
+.TH strnlen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strnlen \- determine the length of a fixed-size string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "size_t strnlen(const char " s [. maxlen "], size_t " maxlen );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strnlen ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR strnlen ()
+function returns the number of bytes in the string
+pointed to by
+.IR s ,
+excluding the terminating null byte (\[aq]\e0\[aq]),
+but at most
+.IR maxlen .
+In doing this,
+.BR strnlen ()
+looks only at the first
+.I maxlen
+characters in the string pointed to by
+.I s
+and never beyond
+.IR s[maxlen\-1] .
+.SH RETURN VALUE
+The
+.BR strnlen ()
+function returns
+.IR strlen(s) ,
+if that is less than
+.IR maxlen ,
+or
+.I maxlen
+if there is no null terminating (\[aq]\e0\[aq]) among the first
+.I maxlen
+characters pointed to by
+.IR s .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strnlen ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2008.
+.SH SEE ALSO
+.BR strlen (3)
diff --git a/man/man3/strpbrk.3 b/man/man3/strpbrk.3
new file mode 100644
index 000000000..7c03d319d
--- /dev/null
+++ b/man/man3/strpbrk.3
@@ -0,0 +1,66 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:01:24 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strpbrk 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strpbrk \- search a string for any of a set of bytes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strpbrk(const char *" s ", const char *" accept );
+.fi
+.SH DESCRIPTION
+The
+.BR strpbrk ()
+function locates the first occurrence in the
+string
+.I s
+of any of the bytes in the string
+.IR accept .
+.SH RETURN VALUE
+The
+.BR strpbrk ()
+function returns a pointer to the byte in
+.I s
+that matches one of the bytes in
+.IR accept ,
+or NULL
+if no such byte is found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strpbrk ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR memchr (3),
+.BR strchr (3),
+.BR string (3),
+.BR strsep (3),
+.BR strspn (3),
+.BR strstr (3),
+.BR strtok (3),
+.BR wcspbrk (3)
diff --git a/man/man3/strptime.3 b/man/man3/strptime.3
new file mode 100644
index 000000000..d936f6e30
--- /dev/null
+++ b/man/man3/strptime.3
@@ -0,0 +1,413 @@
+'\" t
+.\" Copyright 1993 Mitchum DSouza <m.dsouza@mrc-apu.cam.ac.uk>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified, jmv@lucifer.dorms.spbu.ru, 1999-11-08
+.\" Modified, aeb, 2000-04-07
+.\" Updated from glibc docs, C. Scott Ananian, 2001-08-25
+.\" Modified, aeb, 2001-08-31
+.\" Modified, wharms 2001-11-12, remark on white space and example
+.\"
+.TH strptime 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strptime \- convert a string representation of time to a time tm structure
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _XOPEN_SOURCE" "       /* See feature_test_macros(7) */"
+.B #include <time.h>
+.P
+.BI "char *strptime(const char *restrict " s ", const char *restrict " format ,
+.BI "               struct tm *restrict " tm );
+.fi
+.SH DESCRIPTION
+The
+.BR strptime ()
+function is the converse of
+.BR strftime (3);
+it converts the character string pointed to by
+.I s
+to values which are stored in the
+"broken-down time"
+structure pointed to by
+.IR tm ,
+using the format specified by
+.IR format .
+.P
+The broken-down time structure
+.I tm
+is described in
+.BR tm (3type).
+.P
+The
+.I format
+argument
+is a character string that consists of field descriptors and text characters,
+reminiscent of
+.BR scanf (3).
+Each field descriptor consists of a
+.B %
+character followed by another character that specifies the replacement
+for the field descriptor.
+All other characters in the
+.I format
+string must have a matching character in the input string,
+except for whitespace, which matches zero or more
+whitespace characters in the input string.
+There should be white\%space or other alphanumeric characters
+between any two field descriptors.
+.P
+The
+.BR strptime ()
+function processes the input string from left
+to right.
+Each of the three possible input elements (whitespace,
+literal, or format) are handled one after the other.
+If the input cannot be matched to the format string, the function stops.
+The remainder of the format and input strings are not processed.
+.P
+The supported input field descriptors are listed below.
+In case a text string (such as the name of a day of the week or a month name)
+is to be matched, the comparison is case insensitive.
+In case a number is to be matched, leading zeros are
+permitted but not required.
+.TP
+.B %%
+The
+.B %
+character.
+.TP
+.BR %a " or " %A
+The name of the day of the week according to the current locale,
+in abbreviated form or the full name.
+.TP
+.BR %b " or " %B " or " %h
+The month name according to the current locale,
+in abbreviated form or the full name.
+.TP
+.B %c
+The date and time representation for the current locale.
+.TP
+.B %C
+The century number (0\[en]99).
+.TP
+.BR %d " or " %e
+The day of month (1\[en]31).
+.TP
+.B %D
+Equivalent to
+.BR %m/%d/%y .
+(This is the American style date, very confusing
+to non-Americans, especially since
+.B %d/%m/%y
+is widely used in Europe.
+The ISO\~8601 standard format is
+.BR %Y\-%m\-%d .)
+.TP
+.B %H
+The hour (0\[en]23).
+.TP
+.B %I
+The hour on a 12-hour clock (1\[en]12).
+.TP
+.B %j
+The day number in the year (1\[en]366).
+.TP
+.B %m
+The month number (1\[en]12).
+.TP
+.B %M
+The minute (0\[en]59).
+.TP
+.B %n
+Arbitrary whitespace.
+.TP
+.B %p
+The locale's equivalent of AM or PM.
+(Note: there may be none.)
+.TP
+.B %r
+The 12-hour clock time (using the locale's AM or PM).
+In the POSIX locale equivalent to
+.BR "%I:%M:%S %p" .
+If
+.I t_fmt_ampm
+is empty in the
+.B LC_TIME
+part of the current locale,
+then the behavior is undefined.
+.TP
+.B %R
+Equivalent to
+.BR %H:%M .
+.TP
+.B %S
+The second (0\[en]60; 60 may occur for leap seconds;
+earlier also 61 was allowed).
+.TP
+.B %t
+Arbitrary whitespace.
+.TP
+.B %T
+Equivalent to
+.BR %H:%M:%S .
+.TP
+.B %U
+The week number with Sunday the first day of the week (0\[en]53).
+The first Sunday of January is the first day of week 1.
+.TP
+.B %w
+The ordinal number of the day of the week (0\[en]6), with Sunday = 0.
+.TP
+.B %W
+The week number with Monday the first day of the week (0\[en]53).
+The first Monday of January is the first day of week 1.
+.TP
+.B %x
+The date, using the locale's date format.
+.TP
+.B %X
+The time, using the locale's time format.
+.TP
+.B %y
+The year within century (0\[en]99).
+When a century is not otherwise specified, values in the range 69\[en]99 refer
+to years in the twentieth century (1969\[en]1999); values in the
+range 00\[en]68 refer to years in the twenty-first century (2000\[en]2068).
+.TP
+.B %Y
+The year, including century (for example, 1991).
+.P
+Some field descriptors can be modified by the E or O modifier characters
+to indicate that an alternative format or specification should be used.
+If the
+alternative format or specification does not exist in the current locale, the
+unmodified field descriptor is used.
+.P
+The E modifier specifies that the input string may contain
+alternative locale-dependent versions of the date and time representation:
+.TP
+.B %Ec
+The locale's alternative date and time representation.
+.TP
+.B %EC
+The name of the base year (period) in the locale's alternative representation.
+.TP
+.B %Ex
+The locale's alternative date representation.
+.TP
+.B %EX
+The locale's alternative time representation.
+.TP
+.B %Ey
+The offset from
+.B %EC
+(year only) in the locale's alternative representation.
+.TP
+.B %EY
+The full alternative year representation.
+.P
+The O modifier specifies that the numerical input may be in an
+alternative locale-dependent format:
+.TP
+.BR %Od " or " %Oe
+The day of the month using the locale's alternative numeric symbols;
+leading zeros are permitted but not required.
+.TP
+.B %OH
+The hour (24-hour clock) using the locale's alternative numeric symbols.
+.TP
+.B %OI
+The hour (12-hour clock) using the locale's alternative numeric symbols.
+.TP
+.B %Om
+The month using the locale's alternative numeric symbols.
+.TP
+.B %OM
+The minutes using the locale's alternative numeric symbols.
+.TP
+.B %OS
+The seconds using the locale's alternative numeric symbols.
+.TP
+.B %OU
+The week number of the year (Sunday as the first day of the week)
+using the locale's alternative numeric symbols.
+.TP
+.B %Ow
+The ordinal number of the day of the week (Sunday=0),
+using the locale's alternative numeric symbols.
+.TP
+.B %OW
+The week number of the year (Monday as the first day of the week)
+using the locale's alternative numeric symbols.
+.TP
+.B %Oy
+The year (offset from
+.BR %C )
+using the locale's alternative numeric symbols.
+.SH RETURN VALUE
+The return value of the function is a pointer to the first character
+not processed in this function call.
+In case the input string
+contains more characters than required by the format string, the return
+value points right after the last consumed input character.
+In case the whole input string is consumed,
+the return value points to the null byte at the end of the string.
+If
+.BR strptime ()
+fails to match all
+of the format string and therefore an error occurred, the function
+returns NULL.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strptime ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SUSv2.
+.SH NOTES
+In principle, this function does not initialize
+.I tm
+but
+stores only the values specified.
+This means that
+.I tm
+should be initialized before the call.
+Details differ a bit between different UNIX systems.
+The glibc implementation does not touch those fields which are not
+explicitly specified, except that it recomputes the
+.I tm_wday
+and
+.I tm_yday
+field if any of the year, month, or day elements changed.
+.\" .P
+.\" This function is available since libc 4.6.8.
+.\" Linux libc4 and libc5 includes define the prototype unconditionally;
+.\" glibc2 includes provide a prototype only when
+.\" .B _XOPEN_SOURCE
+.\" or
+.\" .B _GNU_SOURCE
+.\" are defined.
+.\" .P
+.\" Before libc 5.4.13 whitespace
+.\" (and the \[aq]n\[aq] and \[aq]t\[aq] specifications) was not handled,
+.\" no \[aq]E\[aq] and \[aq]O\[aq] locale modifier characters were accepted,
+.\" and the \[aq]C\[aq] specification was a synonym for the \[aq]c\[aq] specification.
+.P
+The \[aq]y\[aq] (year in century) specification is taken to specify a year
+.\" in the 20th century by libc4 and libc5.
+.\" It is taken to be a year
+in the range 1950\[en]2049 by glibc 2.0.
+It is taken to be a year in
+1969\[en]2068 since glibc 2.1.
+.\" In libc4 and libc5 the code for %I is broken (fixed in glibc;
+.\" %OI was fixed in glibc 2.2.4).
+.SS glibc notes
+For reasons of symmetry, glibc tries to support for
+.BR strptime ()
+the same format characters as for
+.BR strftime (3).
+(In most cases, the corresponding fields are parsed, but no field in
+.I tm
+is changed.)
+This leads to
+.TP
+.B %F
+Equivalent to
+.BR %Y\-%m\-%d ,
+the ISO\~8601 date format.
+.TP
+.B %g
+The year corresponding to the ISO week number, but without the century
+(0\[en]99).
+.TP
+.B %G
+The year corresponding to the ISO week number.
+(For example, 1991.)
+.TP
+.B %u
+The day of the week as a decimal number (1\[en]7, where Monday = 1).
+.TP
+.B %V
+The ISO\~8601:1988 week number as a decimal number (1\[en]53).
+If the week (starting on Monday) containing 1 January has four or more days
+in the new year, then it is considered week 1.
+Otherwise, it is the last week
+of the previous year, and the next week is week 1.
+.TP
+.B %z
+An RFC-822/ISO\~8601 standard timezone specification.
+.TP
+.B %Z
+The timezone name.
+.P
+Similarly, because of GNU extensions to
+.BR strftime (3),
+.B %k
+is accepted as a synonym for
+.BR %H ,
+and
+.B %l
+should be accepted
+as a synonym for
+.BR %I ,
+and
+.B %P
+is accepted as a synonym for
+.BR %p .
+Finally
+.TP
+.B %s
+The number of seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+Leap seconds are not counted unless leap second support is available.
+.P
+The glibc implementation does not require whitespace between
+two field descriptors.
+.SH EXAMPLES
+The following example demonstrates the use of
+.BR strptime ()
+and
+.BR strftime (3).
+.P
+.\" SRC BEGIN (strptime.c)
+.EX
+#define _XOPEN_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+\&
+int
+main(void)
+{
+    struct tm tm;
+    char buf[255];
+\&
+    memset(&tm, 0, sizeof(tm));
+    strptime("2001\-11\-12 18:31:01", "%Y\-%m\-%d %H:%M:%S", &tm);
+    strftime(buf, sizeof(buf), "%d %b %Y %H:%M", &tm);
+    puts(buf);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR time (2),
+.BR getdate (3),
+.BR scanf (3),
+.BR setlocale (3),
+.BR strftime (3)
diff --git a/man/man3/strrchr.3 b/man/man3/strrchr.3
new file mode 100644
index 000000000..322b7a896
--- /dev/null
+++ b/man/man3/strrchr.3
@@ -0,0 +1 @@
+.so man3/strchr.3
diff --git a/man/man3/strsep.3 b/man/man3/strsep.3
new file mode 100644
index 000000000..baef0facd
--- /dev/null
+++ b/man/man3/strsep.3
@@ -0,0 +1,162 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 18:00:10 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Mon Jan 20 12:04:18 1997 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Tue Jan 23 20:23:07 2001 by Andries Brouwer (aeb@cwi.nl)
+.\"
+.TH strsep 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strsep \- extract token from string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strsep(char **restrict " stringp ", const char *restrict " delim );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strsep ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+If
+.I *stringp
+is NULL, the
+.BR strsep ()
+function returns NULL
+and does nothing else.
+Otherwise, this function finds the first token
+in the string
+.I *stringp
+that is delimited by one of the bytes in the string
+.IR delim .
+This token is terminated by overwriting the delimiter
+with a null byte (\[aq]\e0\[aq]),
+and
+.I *stringp
+is updated to point past the token.
+In case no delimiter was found, the token is taken to be
+the entire string
+.IR *stringp ,
+and
+.I *stringp
+is made NULL.
+.SH RETURN VALUE
+The
+.BR strsep ()
+function returns a pointer to the token,
+that is, it returns the original value of
+.IR *stringp .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strsep ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.4BSD.
+.P
+The
+.BR strsep ()
+function was introduced as a replacement for
+.BR strtok (3),
+since the latter cannot handle empty fields.
+However,
+.BR strtok (3)
+conforms to C89/C99 and hence is more portable.
+.SH BUGS
+Be cautious when using this function.
+If you do use it, note that:
+.IP \[bu] 3
+This function modifies its first argument.
+.IP \[bu]
+This function cannot be used on constant strings.
+.IP \[bu]
+The identity of the delimiting character is lost.
+.SH EXAMPLES
+The program below is a port of the one found in
+.BR strtok (3),
+which, however, doesn't discard multiple delimiters or empty tokens:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \[aq]a/bbb///cc;xxx:yyy:\[aq] \[aq]:;\[aq] \[aq]/\[aq]"
+1: a/bbb///cc
+         \-\-> a
+         \-\-> bbb
+         \-\->
+         \-\->
+         \-\-> cc
+2: xxx
+         \-\-> xxx
+3: yyy
+         \-\-> yyy
+4:
+         \-\->
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (strsep.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    char *token, *subtoken;
+\&
+    if (argc != 4) {
+        fprintf(stderr, "Usage: %s string delim subdelim\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (unsigned int j = 1; (token = strsep(&argv[1], argv[2])); j++) {
+        printf("%u: %s\en", j, token);
+\&
+        while ((subtoken = strsep(&token, argv[3])))
+            printf("\et \-\-> %s\en", subtoken);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR memchr (3),
+.BR strchr (3),
+.BR string (3),
+.BR strpbrk (3),
+.BR strspn (3),
+.BR strstr (3),
+.BR strtok (3)
diff --git a/man/man3/strsignal.3 b/man/man3/strsignal.3
new file mode 100644
index 000000000..3fa49d88a
--- /dev/null
+++ b/man/man3/strsignal.3
@@ -0,0 +1,169 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright (C) 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 17:59:03 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strsignal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strsignal, sigabbrev_np, sigdescr_np, sys_siglist \-
+return string describing signal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strsignal(int " sig );
+.BI "const char *sigdescr_np(int " sig );
+.BI "const char *sigabbrev_np(int " sig );
+.P
+.BI "[[deprecated]] extern const char *const " sys_siglist [];
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR sigabbrev_np (),
+.BR sigdescr_np ():
+.nf
+    _GNU_SOURCE
+.fi
+.P
+.BR strsignal ():
+.nf
+    From glibc 2.10 to glibc 2.31:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.P
+.IR sys_siglist :
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR strsignal ()
+function returns a string describing the signal
+number passed in the argument
+.IR sig .
+The string can be used only until the next call to
+.BR strsignal ().
+The string returned by
+.BR strsignal ()
+is localized according to the
+.B LC_MESSAGES
+category in the current locale.
+.P
+The
+.BR sigdescr_np ()
+function returns a string describing the signal
+number passed in the argument
+.IR sig .
+Unlike
+.BR strsignal ()
+this string is not influenced by the current locale.
+.P
+The
+.BR sigabbrev_np ()
+function returns the abbreviated name of the signal,
+.IR sig .
+For example, given the value
+.BR SIGINT ,
+it returns the string "INT".
+.P
+The (deprecated) array
+.I sys_siglist
+holds the signal description strings
+indexed by signal number.
+The
+.BR strsignal ()
+or the
+.BR sigdescr_np ()
+function should be used instead of this array; see also VERSIONS.
+.SH RETURN VALUE
+The
+.BR strsignal ()
+function returns the appropriate description
+string, or an unknown signal message if the signal number is invalid.
+On some systems (but not on Linux), NULL may instead be
+returned for an invalid signal number.
+.P
+The
+.BR sigdescr_np ()
+and
+.BR sigabbrev_np ()
+functions return the appropriate description string.
+The returned string is statically allocated and valid for
+the lifetime of the program.
+These functions return NULL for an invalid signal number.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strsignal ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:strsignal locale
+T}
+T{
+.na
+.nh
+.BR sigdescr_np (),
+.BR sigabbrev_np ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR strsignal ()
+POSIX.1-2008.
+.TP
+.BR sigdescr_np ()
+.TQ
+.BR sigabbrev_np ()
+GNU.
+.TP
+.I sys_siglist
+None.
+.\" glibc commit b1ccfc061feee9ce616444ded8e1cd5acf9fa97f
+.SH HISTORY
+.TP
+.BR strsignal ()
+POSIX.1-2008.
+Solaris, BSD.
+.TP
+.BR sigdescr_np ()
+.TQ
+.BR sigabbrev_np ()
+glibc 2.32.
+.TP
+.I sys_siglist
+Removed in glibc 2.32.
+.SH NOTES
+.BR sigdescr_np ()
+and
+.BR sigabbrev_np ()
+are thread-safe and async-signal-safe.
+.SH SEE ALSO
+.BR psignal (3),
+.BR strerror (3)
diff --git a/man/man3/strspn.3 b/man/man3/strspn.3
new file mode 100644
index 000000000..94d9a7fab
--- /dev/null
+++ b/man/man3/strspn.3
@@ -0,0 +1,85 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 17:57:50 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strspn 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strspn, strcspn \- get length of a prefix substring
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "size_t strspn(const char *" s ", const char *" accept );
+.BI "size_t strcspn(const char *" s ", const char *" reject );
+.fi
+.SH DESCRIPTION
+The
+.BR strspn ()
+function calculates the length (in bytes) of the initial
+segment of
+.I s
+which consists entirely of bytes in
+.IR accept .
+.P
+The
+.BR strcspn ()
+function calculates the length of the initial
+segment of
+.I s
+which consists entirely of bytes not in
+.IR reject .
+.SH RETURN VALUE
+The
+.BR strspn ()
+function returns the number of bytes in
+the initial segment of
+.I s
+which consist only of bytes
+from
+.IR accept .
+.P
+The
+.BR strcspn ()
+function returns the number of bytes in
+the initial segment of
+.I s
+which are not in the string
+.IR reject .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strspn (),
+.BR strcspn ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR memchr (3),
+.BR strchr (3),
+.BR string (3),
+.BR strpbrk (3),
+.BR strsep (3),
+.BR strstr (3),
+.BR strtok (3),
+.BR wcscspn (3),
+.BR wcsspn (3)
diff --git a/man/man3/strstr.3 b/man/man3/strstr.3
new file mode 100644
index 000000000..d6a066631
--- /dev/null
+++ b/man/man3/strstr.3
@@ -0,0 +1,98 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 17:56:43 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Added history, aeb, 980113.
+.\" 2005-05-05 mtk: added strcasestr()
+.\"
+.TH strstr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strstr, strcasestr \- locate a substring
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strstr(const char *" haystack ", const char *" needle );
+.P
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <string.h>
+.P
+.BI "char *strcasestr(const char *" haystack ", const char *" needle );
+.fi
+.SH DESCRIPTION
+The
+.BR strstr ()
+function finds the first occurrence of the substring
+.I needle
+in the string
+.IR haystack .
+The terminating null bytes (\[aq]\e0\[aq]) are not compared.
+.P
+The
+.BR strcasestr ()
+function is like
+.BR strstr (),
+but ignores the case of both arguments.
+.SH RETURN VALUE
+These functions return a pointer to the beginning of the
+located substring, or NULL if the substring is not found.
+.P
+If
+.I needle
+is the empty string,
+the return value is always
+.I haystack
+itself.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strstr ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR strcasestr ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+.TP
+.BR strstr ()
+C11, POSIX.1-2008.
+.TP
+.BR strcasestr ()
+GNU.
+.SH HISTORY
+.TP
+.BR strstr ()
+POSIX.1-2001, C89.
+.TP
+.BR strcasestr ()
+GNU.
+.SH SEE ALSO
+.BR memchr (3),
+.BR memmem (3),
+.BR strcasecmp (3),
+.BR strchr (3),
+.BR string (3),
+.BR strpbrk (3),
+.BR strsep (3),
+.BR strspn (3),
+.BR strtok (3),
+.BR wcsstr (3)
diff --git a/man/man3/strtod.3 b/man/man3/strtod.3
new file mode 100644
index 000000000..fdcf5574b
--- /dev/null
+++ b/man/man3/strtod.3
@@ -0,0 +1,205 @@
+'\" t
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" the American National Standards Committee X3, on Information
+.\" Processing Systems.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)strtod.3	5.3 (Berkeley) 6/29/91
+.\"
+.\" Modified Sun Aug 21 17:16:22 1994 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sat May 04 19:34:31 MET DST 1996 by Michael Haardt
+.\"   (michael@cantor.informatik.rwth-aachen.de)
+.\" Added strof, strtold, aeb, 2001-06-07
+.\"
+.TH strtod 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strtod, strtof, strtold \- convert ASCII string to floating-point number
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "double strtod(const char *restrict " nptr ", char **restrict " endptr );
+.BI "float strtof(const char *restrict " nptr ", char **restrict " endptr );
+.BI "long double strtold(const char *restrict " nptr \
+", char **restrict " endptr );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strtof (),
+.BR strtold ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR strtod (),
+.BR strtof (),
+and
+.BR strtold ()
+functions convert the initial portion of the string pointed to by
+.I nptr
+to
+.IR double ,
+.IR float ,
+and
+.I long double
+representation, respectively.
+.P
+The expected form of the (initial portion of the) string is
+optional leading white space as recognized by
+.BR isspace (3),
+an optional plus (\[aq]+\[aq]) or minus sign (\[aq]\-\[aq]) and then either
+(i) a decimal number, or (ii) a hexadecimal number,
+or (iii) an infinity, or (iv) a NAN (not-a-number).
+.P
+A
+.I "decimal number"
+consists of a nonempty sequence of decimal digits
+possibly containing a radix character (decimal point, locale-dependent,
+usually \[aq].\[aq]), optionally followed by a decimal exponent.
+A decimal exponent consists of an \[aq]E\[aq] or \[aq]e\[aq], followed by an
+optional plus or minus sign, followed by a nonempty sequence of
+decimal digits, and indicates multiplication by a power of 10.
+.P
+A
+.I "hexadecimal number"
+consists of a "0x" or "0X" followed by a nonempty sequence of
+hexadecimal digits possibly containing a radix character,
+optionally followed by a binary exponent.
+A binary exponent
+consists of a \[aq]P\[aq] or \[aq]p\[aq], followed by an optional
+plus or minus sign, followed by a nonempty sequence of
+decimal digits, and indicates multiplication by a power of 2.
+At least one of radix character and binary exponent must be present.
+.P
+An
+.I infinity
+is either "INF" or "INFINITY", disregarding case.
+.P
+A
+.I NAN
+is "NAN" (disregarding case) optionally followed by a string,
+.IR (n-char-sequence) ,
+where
+.I n-char-sequence
+specifies in an implementation-dependent
+way the type of NAN (see NOTES).
+.SH RETURN VALUE
+These functions return the converted value, if any.
+.P
+If
+.I endptr
+is not NULL,
+a pointer to the character after the last character used in the conversion
+is stored in the location referenced by
+.IR endptr .
+.P
+If no conversion is performed, zero is returned and (unless
+.I endptr
+is null) the value of
+.I nptr
+is stored in the location referenced by
+.IR endptr .
+.P
+If the correct value would cause overflow, plus or minus
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.B HUGE_VALL
+is returned (according to the return type and sign of the value),
+and
+.B ERANGE
+is stored in
+.IR errno .
+.P
+If the correct value would cause underflow,
+a value with magnitude no larger than
+.BR DBL_MIN ,
+.BR FLT_MIN ,
+or
+.B LDBL_MIN
+is returned and
+.B ERANGE
+is stored in
+.IR errno .
+.SH ERRORS
+.TP
+.B ERANGE
+Overflow or underflow occurred.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strtod (),
+.BR strtof (),
+.BR strtold ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH VERSIONS
+In the glibc implementation, the
+.I n-char-sequence
+that optionally follows "NAN"
+is interpreted as an integer number
+(with an optional '0' or '0x' prefix to select base 8 or 16)
+that is to be placed in the
+mantissa component of the returned value.
+.\" From glibc 2.8's stdlib/strtod_l.c:
+.\"     We expect it to be a number which is put in the
+.\"     mantissa of the number.
+.\" It looks as though at least FreeBSD (according to the manual) does
+.\" something similar.
+.\" C11 says: "An implementation may use the n-char sequence to determine
+.\"	extra information to be represented in the NaN's significant."
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR strtod ()
+C89, POSIX.1-2001.
+.TP
+.BR strtof ()
+.TQ
+.BR strtold ()
+C99, POSIX.1-2001.
+.SH NOTES
+Since
+0 can legitimately be returned
+on both success and failure, the calling program should set
+.I errno
+to 0 before the call,
+and then determine if an error occurred by checking whether
+.I errno
+has a nonzero value after the call.
+.SH EXAMPLES
+See the example on the
+.BR strtol (3)
+manual page;
+the use of the functions described in this manual page is similar.
+.SH SEE ALSO
+.BR atof (3),
+.BR atoi (3),
+.BR atol (3),
+.BR nan (3),
+.BR nanf (3),
+.BR nanl (3),
+.BR strfromd (3),
+.BR strtol (3),
+.BR strtoul (3)
diff --git a/man/man3/strtof.3 b/man/man3/strtof.3
new file mode 100644
index 000000000..ac3e4a55c
--- /dev/null
+++ b/man/man3/strtof.3
@@ -0,0 +1 @@
+.so man3/strtod.3
diff --git a/man/man3/strtoimax.3 b/man/man3/strtoimax.3
new file mode 100644
index 000000000..a0499ec2a
--- /dev/null
+++ b/man/man3/strtoimax.3
@@ -0,0 +1,68 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH strtoimax 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strtoimax, strtoumax \- convert string to integer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <inttypes.h>
+.P
+.BI "intmax_t strtoimax(const char *restrict " nptr ", char **restrict " endptr ,
+.BI "                   int " base );
+.BI "uintmax_t strtoumax(const char *restrict " nptr ", char **restrict " endptr ,
+.BI "                   int " base );
+.fi
+.SH DESCRIPTION
+These functions are just like
+.BR strtol (3)
+and
+.BR strtoul (3),
+except that they return a value of type
+.I intmax_t
+and
+.IR uintmax_t ,
+respectively.
+.SH RETURN VALUE
+On success, the converted value is returned.
+If nothing was found to convert, zero is returned.
+On overflow or underflow
+.B INTMAX_MAX
+or
+.B INTMAX_MIN
+or
+.B UINTMAX_MAX
+is returned, and
+.I errno
+is set to
+.BR ERANGE .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strtoimax (),
+.BR strtoumax ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR imaxabs (3),
+.BR imaxdiv (3),
+.BR strtol (3),
+.BR strtoul (3),
+.BR wcstoimax (3)
diff --git a/man/man3/strtok.3 b/man/man3/strtok.3
new file mode 100644
index 000000000..34a90198c
--- /dev/null
+++ b/man/man3/strtok.3
@@ -0,0 +1,288 @@
+'\" t
+.\" Copyright (C) 2005, 2013 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" a few fragments from an earlier (1996) version by
+.\" Andries Brouwer (aeb@cwi.nl) remain.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Rewritten old page, 960210, aeb@cwi.nl
+.\" Updated, added strtok_r. 2000-02-13 Nicolás Lichtmaier <nick@debian.org>
+.\" 2005-11-17, mtk: Substantial parts rewritten
+.\" 2013-05-19, mtk: added much further detail on the operation of strtok()
+.\"
+.TH strtok 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strtok, strtok_r \- extract tokens from strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "char *strtok(char *restrict " str ", const char *restrict " delim );
+.BI "char *strtok_r(char *restrict " str ", const char *restrict " delim ,
+.BI "               char **restrict " saveptr );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strtok_r ():
+.nf
+    _POSIX_C_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR strtok ()
+function breaks a string into a sequence of zero or more nonempty tokens.
+On the first call to
+.BR strtok (),
+the string to be parsed should be
+specified in
+.IR str .
+In each subsequent call that should parse the same string,
+.I str
+must be NULL.
+.P
+The
+.I delim
+argument specifies a set of bytes that
+delimit the tokens in the parsed string.
+The caller may specify different strings in
+.I delim
+in successive
+calls that parse the same string.
+.P
+Each call to
+.BR strtok ()
+returns a pointer to a
+null-terminated string containing the next token.
+This string does not include the delimiting byte.
+If no more tokens are found,
+.BR strtok ()
+returns NULL.
+.P
+A sequence of calls to
+.BR strtok ()
+that operate on the same string maintains a pointer
+that determines the point from which to start searching for the next token.
+The first call to
+.BR strtok ()
+sets this pointer to point to the first byte of the string.
+The start of the next token is determined by scanning forward
+for the next nondelimiter byte in
+.IR str .
+If such a byte is found, it is taken as the start of the next token.
+If no such byte is found,
+then there are no more tokens, and
+.BR strtok ()
+returns NULL.
+(A string that is empty or that contains only delimiters
+will thus cause
+.BR strtok ()
+to return NULL on the first call.)
+.P
+The end of each token is found by scanning forward until either
+the next delimiter byte is found or until the
+terminating null byte (\[aq]\e0\[aq]) is encountered.
+If a delimiter byte is found, it is overwritten with
+a null byte to terminate the current token, and
+.BR strtok ()
+saves a pointer to the following byte;
+that pointer will be used as the starting point
+when searching for the next token.
+In this case,
+.BR strtok ()
+returns a pointer to the start of the found token.
+.P
+From the above description,
+it follows that a sequence of two or more contiguous delimiter bytes in
+the parsed string is considered to be a single delimiter, and that
+delimiter bytes at the start or end of the string are ignored.
+Put another way: the tokens returned by
+.BR strtok ()
+are always nonempty strings.
+Thus, for example, given the string "\fIaaa;;bbb,\fP",
+successive calls to
+.BR strtok ()
+that specify the delimiter string "\fI;,\fP"
+would return the strings "\fIaaa\fP" and "\fIbbb\fP",
+and then a null pointer.
+.P
+The
+.BR strtok_r ()
+function is a reentrant version of
+.BR strtok ().
+The
+.I saveptr
+argument is a pointer to a
+.I char\~*
+variable that is used internally by
+.BR strtok_r ()
+in order to maintain context between successive calls that parse the
+same string.
+.P
+On the first call to
+.BR strtok_r (),
+.I str
+should point to the string to be parsed, and the value of
+.I *saveptr
+is ignored (but see NOTES).
+In subsequent calls,
+.I str
+should be NULL, and
+.I saveptr
+(and the buffer that it points to)
+should be unchanged since the previous call.
+.P
+Different strings may be parsed concurrently using sequences of calls to
+.BR strtok_r ()
+that specify different
+.I saveptr
+arguments.
+.SH RETURN VALUE
+The
+.BR strtok ()
+and
+.BR strtok_r ()
+functions return a pointer to
+the next token, or NULL if there are no more tokens.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strtok ()
+T}	Thread safety	MT-Unsafe race:strtok
+T{
+.na
+.nh
+.BR strtok_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+On some implementations,
+.\" Tru64, according to its manual page
+.I *saveptr
+is required to be NULL on the first call to
+.BR strtok_r ()
+that is being used to parse
+.IR str .
+.SH STANDARDS
+.TP
+.BR strtok ()
+C11, POSIX.1-2008.
+.TP
+.BR strtok_r ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR strtok ()
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.TP
+.BR strtok_r ()
+POSIX.1-2001.
+.SH BUGS
+Be cautious when using these functions.
+If you do use them, note that:
+.IP \[bu] 3
+These functions modify their first argument.
+.IP \[bu]
+These functions cannot be used on constant strings.
+.IP \[bu]
+The identity of the delimiting byte is lost.
+.IP \[bu]
+The
+.BR strtok ()
+function uses a static buffer while parsing, so it's not thread safe.
+Use
+.BR strtok_r ()
+if this matters to you.
+.SH EXAMPLES
+The program below uses nested loops that employ
+.BR strtok_r ()
+to break a string into a two-level hierarchy of tokens.
+The first command-line argument specifies the string to be parsed.
+The second argument specifies the delimiter byte(s)
+to be used to separate that string into "major" tokens.
+The third argument specifies the delimiter byte(s)
+to be used to separate the "major" tokens into subtokens.
+.P
+An example of the output produced by this program is the following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \[aq]a/bbb///cc;xxx:yyy:\[aq] \[aq]:;\[aq] \[aq]/\[aq]"
+1: a/bbb///cc
+         \-\-> a
+         \-\-> bbb
+         \-\-> cc
+2: xxx
+         \-\-> xxx
+3: yyy
+         \-\-> yyy
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (strtok.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    char *str1, *str2, *token, *subtoken;
+    char *saveptr1, *saveptr2;
+    int j;
+\&
+    if (argc != 4) {
+        fprintf(stderr, "Usage: %s string delim subdelim\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (j = 1, str1 = argv[1]; ; j++, str1 = NULL) {
+        token = strtok_r(str1, argv[2], &saveptr1);
+        if (token == NULL)
+            break;
+        printf("%d: %s\en", j, token);
+\&
+        for (str2 = token; ; str2 = NULL) {
+            subtoken = strtok_r(str2, argv[3], &saveptr2);
+            if (subtoken == NULL)
+                break;
+            printf("\et \-\-> %s\en", subtoken);
+        }
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.P
+Another example program using
+.BR strtok ()
+can be found in
+.BR getaddrinfo_a (3).
+.SH SEE ALSO
+.BR memchr (3),
+.BR strchr (3),
+.BR string (3),
+.BR strpbrk (3),
+.BR strsep (3),
+.BR strspn (3),
+.BR strstr (3),
+.BR wcstok (3)
diff --git a/man/man3/strtok_r.3 b/man/man3/strtok_r.3
new file mode 100644
index 000000000..19095a017
--- /dev/null
+++ b/man/man3/strtok_r.3
@@ -0,0 +1 @@
+.so man3/strtok.3
diff --git a/man/man3/strtol.3 b/man/man3/strtol.3
new file mode 100644
index 000000000..c05eac0ec
--- /dev/null
+++ b/man/man3/strtol.3
@@ -0,0 +1,321 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2006 Michael Kerrisk <mtk.manpages@ganil.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:53:39 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Added correction due to nsd@bbc.com (Nick Duffek) - aeb, 950610
+.TH strtol 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strtol, strtoll, strtoq \- convert a string to a long integer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "long strtol(const char *restrict " nptr ,
+.BI "            char **restrict " endptr ", int " base );
+.BI "long long strtoll(const char *restrict " nptr ,
+.BI "            char **restrict " endptr ", int " base );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strtoll ():
+.nf
+    _ISOC99_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR strtol ()
+function converts the initial part of the string
+in
+.I nptr
+to a long integer value according to the given
+.IR base ,
+which must be between 2 and 36 inclusive, or be the special value 0.
+.P
+The string may begin with an arbitrary amount of white space (as
+determined by
+.BR isspace (3))
+followed by a single optional \[aq]+\[aq] or \[aq]\-\[aq] sign.
+If
+.I base
+is zero or 16, the string may then include a
+"0x" or "0X" prefix, and the number will be read in base 16; otherwise, a
+zero
+.I base
+is taken as 10 (decimal) unless the next character
+is \[aq]0\[aq], in which case it is taken as 8 (octal).
+.P
+The remainder of the string is converted to a
+.I long
+value
+in the obvious manner, stopping at the first character which is not a
+valid digit in the given base.
+(In bases above 10, the letter \[aq]A\[aq] in
+either uppercase or lowercase represents 10, \[aq]B\[aq] represents 11, and so
+forth, with \[aq]Z\[aq] representing 35.)
+.P
+If
+.I endptr
+is not NULL,
+and the
+.I base
+is supported,
+.BR strtol ()
+stores the address of the
+first invalid character in
+.IR *endptr .
+If there were no digits at
+all,
+.BR strtol ()
+stores the original value of
+.I nptr
+in
+.I *endptr
+(and returns 0).
+In particular, if
+.I *nptr
+is not \[aq]\e0\[aq] but
+.I **endptr
+is \[aq]\e0\[aq] on return, the entire string is valid.
+.P
+The
+.BR strtoll ()
+function works just like the
+.BR strtol ()
+function but returns a
+.I long long
+integer value.
+.SH RETURN VALUE
+The
+.BR strtol ()
+function returns the result of the conversion,
+unless the value would underflow or overflow.
+If an underflow occurs,
+.BR strtol ()
+returns
+.BR LONG_MIN .
+If an overflow occurs,
+.BR strtol ()
+returns
+.BR LONG_MAX .
+In both cases,
+.I errno
+is set to
+.BR ERANGE .
+Precisely the same holds for
+.BR strtoll ()
+(with
+.B LLONG_MIN
+and
+.B LLONG_MAX
+instead of
+.B LONG_MIN
+and
+.BR LONG_MAX ).
+.SH ERRORS
+This function does not modify
+.I errno
+on success.
+.TP
+.B EINVAL
+(not in C99)
+The given
+.I base
+contains an unsupported value.
+.TP
+.B ERANGE
+The resulting value was out of range.
+.P
+The implementation may also set
+.I errno
+to
+.B EINVAL
+in case
+no conversion was performed (no digits seen, and 0 returned).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strtol (),
+.BR strtoll (),
+.BR strtoq ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR strtol ()
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.TP
+.BR strtoll ()
+POSIX.1-2001, C99.
+.SH NOTES
+Since
+.BR strtol ()
+can legitimately return 0,
+.BR LONG_MAX ,
+or
+.B LONG_MIN
+.RB ( LLONG_MAX
+or
+.B LLONG_MIN
+for
+.BR strtoll ())
+on both success and failure, the calling program should set
+.I errno
+to 0 before the call,
+and then determine if an error occurred by checking whether
+.I errno == ERANGE
+after the call.
+.P
+According to POSIX.1,
+in locales other than "C" and "POSIX",
+these functions may accept other,
+implementation-defined numeric strings.
+.P
+BSD also has
+.P
+.in +4n
+.EX
+.BI "quad_t strtoq(const char *" nptr ", char **" endptr ", int " base );
+.EE
+.in
+.P
+with completely analogous definition.
+Depending on the wordsize of the current architecture, this
+may be equivalent to
+.BR strtoll ()
+or to
+.BR strtol ().
+.SH CAVEATS
+If the
+.I base
+needs to be tested,
+it should be tested in a call where the string is known to succeed.
+Otherwise, it's impossible to portably differentiate the errors.
+.P
+.in +4n
+.EX
+errno = 0;
+strtol("0", NULL, base);
+if (errno == EINVAL)
+    goto unsupported_base;
+.EE
+.in
+.SH EXAMPLES
+The program shown below demonstrates the use of
+.BR strtol ().
+The first command-line argument specifies a string from which
+.BR strtol ()
+should parse a number.
+The second (optional) argument specifies the base to be used for
+the conversion.
+(This argument is converted to numeric form using
+.BR atoi (3),
+a function that performs no error checking and
+has a simpler interface than
+.BR strtol ().)
+Some examples of the results produced by this program are the following:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out 123"
+strtol() returned 123
+.RB "$" " ./a.out \[aq]    123\[aq]"
+strtol() returned 123
+.RB "$" " ./a.out 123abc"
+strtol() returned 123
+Further characters after number: "abc"
+.RB "$" " ./a.out 123abc 55"
+strtol: Invalid argument
+.RB "$" " ./a.out \[aq]\[aq]"
+No digits were found
+.RB "$" " ./a.out 4000000000"
+strtol: Numerical result out of range
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (strtol.c)
+.EX
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int base;
+    char *endptr, *str;
+    long val;
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s str [base]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    str = argv[1];
+    base = (argc > 2) ? atoi(argv[2]) : 0;
+\&
+    errno = 0;    /* To distinguish success/failure after call */
+    strtol("0", NULL, base);
+    if (errno == EINVAL) {
+        perror("strtol");
+        exit(EXIT_FAILURE);
+    }
+\&
+    errno = 0;    /* To distinguish success/failure after call */
+    val = strtol(str, &endptr, base);
+\&
+    /* Check for various possible errors. */
+\&
+    if (errno == ERANGE) {
+        perror("strtol");
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (endptr == str) {
+        fprintf(stderr, "No digits were found\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* If we got here, strtol() successfully parsed a number. */
+\&
+    printf("strtol() returned %ld\en", val);
+\&
+    if (*endptr != \[aq]\e0\[aq])        /* Not necessarily an error... */
+        printf("Further characters after number: \e"%s\e"\en", endptr);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR atof (3),
+.BR atoi (3),
+.BR atol (3),
+.BR strtod (3),
+.BR strtoimax (3),
+.BR strtoul (3)
diff --git a/man/man3/strtold.3 b/man/man3/strtold.3
new file mode 100644
index 000000000..ac3e4a55c
--- /dev/null
+++ b/man/man3/strtold.3
@@ -0,0 +1 @@
+.so man3/strtod.3
diff --git a/man/man3/strtoll.3 b/man/man3/strtoll.3
new file mode 100644
index 000000000..d09039391
--- /dev/null
+++ b/man/man3/strtoll.3
@@ -0,0 +1 @@
+.so man3/strtol.3
diff --git a/man/man3/strtoq.3 b/man/man3/strtoq.3
new file mode 100644
index 000000000..d09039391
--- /dev/null
+++ b/man/man3/strtoq.3
@@ -0,0 +1 @@
+.so man3/strtol.3
diff --git a/man/man3/strtoul.3 b/man/man3/strtoul.3
new file mode 100644
index 000000000..09b1a7cac
--- /dev/null
+++ b/man/man3/strtoul.3
@@ -0,0 +1,224 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:54:03 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Fixed typo, aeb, 950823
+.\" 2002-02-22, joey, mihtjel: Added strtoull()
+.\"
+.TH strtoul 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strtoul, strtoull, strtouq \- convert a string to an unsigned long integer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "unsigned long strtoul(const char *restrict " nptr ,
+.BI "                      char **restrict " endptr ", int " base );
+.BI "unsigned long long strtoull(const char *restrict " nptr ,
+.BI "                      char **restrict " endptr ", int " base );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR strtoull ():
+.nf
+    _ISOC99_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR strtoul ()
+function converts the initial part of the string
+in
+.I nptr
+to an
+.I "unsigned long"
+value according to the
+given
+.IR base ,
+which must be between 2 and 36 inclusive, or be
+the special value 0.
+.P
+The string may begin with an arbitrary amount of white space (as
+determined by
+.BR isspace (3))
+followed by a single optional \[aq]+\[aq] or \[aq]\-\[aq]
+sign.
+If
+.I base
+is zero or 16, the string may then include a
+"0x" prefix, and the number will be read in base 16; otherwise, a
+zero
+.I base
+is taken as 10 (decimal) unless the next character
+is \[aq]0\[aq], in which case it is taken as 8 (octal).
+.P
+The remainder of the string is converted to an
+.I "unsigned long"
+value in the obvious manner,
+stopping at the first character which is not a
+valid digit in the given base.
+(In bases above 10, the letter \[aq]A\[aq] in
+either uppercase or lowercase represents 10, \[aq]B\[aq] represents 11, and so
+forth, with \[aq]Z\[aq] representing 35.)
+.P
+If
+.I endptr
+is not NULL,
+and the
+.I base
+is supported,
+.BR strtoul ()
+stores the address of the
+first invalid character in
+.IR *endptr .
+If there were no digits at
+all,
+.BR strtoul ()
+stores the original value of
+.I nptr
+in
+.I *endptr
+(and returns 0).
+In particular, if
+.I *nptr
+is not \[aq]\e0\[aq] but
+.I **endptr
+is \[aq]\e0\[aq] on return, the entire string is valid.
+.P
+The
+.BR strtoull ()
+function works just like the
+.BR strtoul ()
+function but returns an
+.I "unsigned long long"
+value.
+.SH RETURN VALUE
+The
+.BR strtoul ()
+function returns either the result of the conversion
+or, if there was a leading minus sign, the negation of the result of the
+conversion represented as an unsigned value,
+unless the original (nonnegated) value would overflow; in
+the latter case,
+.BR strtoul ()
+returns
+.B ULONG_MAX
+and sets
+.I errno
+to
+.BR ERANGE .
+Precisely the same holds for
+.BR strtoull ()
+(with
+.B ULLONG_MAX
+instead of
+.BR ULONG_MAX ).
+.SH ERRORS
+This function does not modify
+.I errno
+on success.
+.TP
+.B EINVAL
+(not in C99)
+The given
+.I base
+contains an unsupported value.
+.TP
+.B ERANGE
+The resulting value was out of range.
+.P
+The implementation may also set
+.I errno
+to
+.B EINVAL
+in case
+no conversion was performed (no digits seen, and 0 returned).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strtoul (),
+.BR strtoull (),
+.BR strtouq ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR strtoul ()
+POSIX.1-2001, C89, SVr4.
+.TP
+.BR strtoull ()
+POSIX.1-2001, C99.
+.SH NOTES
+Since
+.BR strtoul ()
+can legitimately return 0 or
+.B ULONG_MAX
+.RB ( ULLONG_MAX
+for
+.BR strtoull ())
+on both success and failure, the calling program should set
+.I errno
+to 0 before the call,
+and then determine if an error occurred by checking whether
+.I errno
+has a nonzero value after the call.
+.P
+In locales other than the "C" locale, other strings may be accepted.
+(For example, the thousands separator of the current locale may be
+supported.)
+.P
+BSD also has
+.P
+.in +4n
+.EX
+.BI "u_quad_t strtouq(const char *" nptr ", char **" endptr ", int " base );
+.EE
+.in
+.P
+with completely analogous definition.
+Depending on the wordsize of the current architecture, this
+may be equivalent to
+.BR strtoull ()
+or to
+.BR strtoul ().
+.P
+Negative values are considered valid input and are
+silently converted to the equivalent
+.I "unsigned long"
+value.
+.SH EXAMPLES
+See the example on the
+.BR strtol (3)
+manual page;
+the use of the functions described in this manual page is similar.
+.SH SEE ALSO
+.BR a64l (3),
+.BR atof (3),
+.BR atoi (3),
+.BR atol (3),
+.BR strtod (3),
+.BR strtol (3),
+.BR strtoumax (3)
diff --git a/man/man3/strtoull.3 b/man/man3/strtoull.3
new file mode 100644
index 000000000..3340a8373
--- /dev/null
+++ b/man/man3/strtoull.3
@@ -0,0 +1 @@
+.so man3/strtoul.3
diff --git a/man/man3/strtoumax.3 b/man/man3/strtoumax.3
new file mode 100644
index 000000000..753be84df
--- /dev/null
+++ b/man/man3/strtoumax.3
@@ -0,0 +1 @@
+.so man3/strtoimax.3
diff --git a/man/man3/strtouq.3 b/man/man3/strtouq.3
new file mode 100644
index 000000000..3340a8373
--- /dev/null
+++ b/man/man3/strtouq.3
@@ -0,0 +1 @@
+.so man3/strtoul.3
diff --git a/man/man3/strverscmp.3 b/man/man3/strverscmp.3
new file mode 100644
index 000000000..b4cf52414
--- /dev/null
+++ b/man/man3/strverscmp.3
@@ -0,0 +1,146 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
+.\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH strverscmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strverscmp \- compare two version strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <string.h>
+.P
+.BI "int strverscmp(const char *" s1 ", const char *" s2 );
+.fi
+.SH DESCRIPTION
+Often one has files
+.IR jan1 ", " jan2 ", ..., " jan9 ", " jan10 ", ..."
+and it feels wrong when
+.BR ls (1)
+orders them
+.IR jan1 ", " jan10 ", ..., " jan2 ", ..., " jan9 .
+.\" classical solution: "rename jan jan0 jan?"
+In order to rectify this, GNU introduced the
+.I \-v
+option to
+.BR ls (1),
+which is implemented using
+.BR versionsort (3),
+which again uses
+.BR strverscmp ().
+.P
+Thus, the task of
+.BR strverscmp ()
+is to compare two strings and find the "right" order, while
+.BR strcmp (3)
+finds only the lexicographic order.
+This function does not use
+the locale category
+.BR LC_COLLATE ,
+so is meant mostly for situations
+where the strings are expected to be in ASCII.
+.P
+What this function does is the following.
+If both strings are equal, return 0.
+Otherwise, find the position
+between two bytes with the property that before it both strings are equal,
+while directly after it there is a difference.
+Find the largest consecutive digit strings containing (or starting at,
+or ending at) this position.
+If one or both of these is empty,
+then return what
+.BR strcmp (3)
+would have returned (numerical ordering of byte values).
+Otherwise, compare both digit strings numerically, where digit strings with
+one or more leading zeros are interpreted as if they have a decimal point
+in front (so that in particular digit strings with more leading zeros
+come before digit strings with fewer leading zeros).
+Thus, the ordering is
+.IR 000 ", " 00 ", " 01 ", " 010 ", " 09 ", " 0 ", " 1 ", " 9 ", " 10 .
+.SH RETURN VALUE
+The
+.BR strverscmp ()
+function returns an integer
+less than, equal to, or greater than zero if
+.I s1
+is found, respectively, to be earlier than, equal to,
+or later than
+.IR s2 .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strverscmp ()
+T}	Thread safety	MT-Safe
+.TE
+.\" FIXME: The marking is different from that in the glibc manual,
+.\" which has:
+.\"
+.\"     strverscmp: MT-Safe locale
+.\"
+.\" glibc manual says strverscmp should have marking locale because it calls
+.\" isdigit() multiple times and isdigit() uses locale variable.
+.\" But isdigit() has two implementations. With different compiling conditions,
+.\" we may call isdigit() in macro, then strverscmp() should not have locale
+.\" problem.
+.SH STANDARDS
+GNU.
+.SH EXAMPLES
+The program below can be used to demonstrate the behavior of
+.BR strverscmp ().
+It uses
+.BR strverscmp ()
+to compare the two strings given as its command-line arguments.
+An example of its use is the following:
+.P
+.in +4n
+.EX
+$ \fB./a.out jan1 jan10\fP
+jan1 < jan10
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (strverscmp.c)
+.EX
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    int res;
+\&
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <string1> <string2>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    res = strverscmp(argv[1], argv[2]);
+\&
+    printf("%s %s %s\en", argv[1],
+           (res < 0) ? "<" : (res == 0) ? "==" : ">", argv[2]);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR rename (1),
+.BR strcasecmp (3),
+.BR strcmp (3),
+.BR strcoll (3)
diff --git a/man/man3/strxfrm.3 b/man/man3/strxfrm.3
new file mode 100644
index 000000000..ccc994b42
--- /dev/null
+++ b/man/man3/strxfrm.3
@@ -0,0 +1,86 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 10:41:28 1993 by Rik Faith (faith@cs.unc.edu)
+.TH strxfrm 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+strxfrm \- string transformation
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <string.h>
+.P
+.BI "size_t strxfrm(char " dest "[restrict ." n "], \
+const char " src "[restrict ." n ],
+.BI "               size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR strxfrm ()
+function transforms the
+.I src
+string into a
+form such that the result of
+.BR strcmp (3)
+on two strings that have
+been transformed with
+.BR strxfrm ()
+is the same as the result of
+.BR strcoll (3)
+on the two strings before their transformation.
+The first
+.I n
+bytes of the transformed string are placed in
+.IR dest .
+The transformation is based on the program's current
+locale for category
+.BR LC_COLLATE .
+(See
+.BR setlocale (3)).
+.SH RETURN VALUE
+The
+.BR strxfrm ()
+function returns the number of bytes required to
+store the transformed string in
+.I dest
+excluding the
+terminating null byte (\[aq]\e0\[aq]).
+If the value returned is
+.I n
+or more, the
+contents of
+.I dest
+are indeterminate.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR strxfrm ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR memcmp (3),
+.BR setlocale (3),
+.BR strcasecmp (3),
+.BR strcmp (3),
+.BR strcoll (3),
+.BR string (3)
diff --git a/man/man3/svc_destroy.3 b/man/man3/svc_destroy.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_destroy.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_freeargs.3 b/man/man3/svc_freeargs.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_freeargs.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_getargs.3 b/man/man3/svc_getargs.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_getargs.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_getcaller.3 b/man/man3/svc_getcaller.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_getcaller.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_getreq.3 b/man/man3/svc_getreq.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_getreq.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_getreqset.3 b/man/man3/svc_getreqset.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_getreqset.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_register.3 b/man/man3/svc_register.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_register.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_run.3 b/man/man3/svc_run.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_run.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_sendreply.3 b/man/man3/svc_sendreply.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_sendreply.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svc_unregister.3 b/man/man3/svc_unregister.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svc_unregister.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcerr_auth.3 b/man/man3/svcerr_auth.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcerr_auth.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcerr_decode.3 b/man/man3/svcerr_decode.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcerr_decode.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcerr_noproc.3 b/man/man3/svcerr_noproc.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcerr_noproc.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcerr_noprog.3 b/man/man3/svcerr_noprog.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcerr_noprog.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcerr_progvers.3 b/man/man3/svcerr_progvers.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcerr_progvers.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcerr_systemerr.3 b/man/man3/svcerr_systemerr.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcerr_systemerr.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcerr_weakauth.3 b/man/man3/svcerr_weakauth.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcerr_weakauth.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcfd_create.3 b/man/man3/svcfd_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcfd_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcraw_create.3 b/man/man3/svcraw_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcraw_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svctcp_create.3 b/man/man3/svctcp_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svctcp_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcudp_bufcreate.3 b/man/man3/svcudp_bufcreate.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcudp_bufcreate.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/svcudp_create.3 b/man/man3/svcudp_create.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/svcudp_create.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/swab.3 b/man/man3/swab.3
new file mode 100644
index 000000000..71023d79a
--- /dev/null
+++ b/man/man3/swab.3
@@ -0,0 +1,76 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 17:52:15 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2001-12-15, aeb
+.TH swab 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+swab \- swap adjacent bytes
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _XOPEN_SOURCE" "       /* See feature_test_macros(7) */"
+.B #include <unistd.h>
+.P
+.BI "void swab(const void " from "[restrict ." n "], void " to "[restrict ." n ],
+.BI "          ssize_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR swab ()
+function copies
+.I n
+bytes from the array pointed
+to by
+.I from
+to the array pointed to by
+.IR to ,
+exchanging
+adjacent even and odd bytes.
+This function is used to exchange data
+between machines that have different low/high byte ordering.
+.P
+This function does nothing when
+.I n
+is negative.
+When
+.I n
+is positive and odd, it handles
+.I n\-1
+bytes
+as above, and does something unspecified with the last byte.
+(In other words,
+.I n
+should be even.)
+.SH RETURN VALUE
+The
+.BR swab ()
+function returns no value.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR swab ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.SH SEE ALSO
+.BR bstring (3)
diff --git a/man/man3/swapcontext.3 b/man/man3/swapcontext.3
new file mode 100644
index 000000000..cdccd64ec
--- /dev/null
+++ b/man/man3/swapcontext.3
@@ -0,0 +1 @@
+.so man3/makecontext.3
diff --git a/man/man3/swprintf.3 b/man/man3/swprintf.3
new file mode 100644
index 000000000..56ec9685b
--- /dev/null
+++ b/man/man3/swprintf.3
@@ -0,0 +1 @@
+.so man3/wprintf.3
diff --git a/man/man3/sys_errlist.3 b/man/man3/sys_errlist.3
new file mode 100644
index 000000000..837f1a191
--- /dev/null
+++ b/man/man3/sys_errlist.3
@@ -0,0 +1 @@
+.so man3/perror.3
diff --git a/man/man3/sys_nerr.3 b/man/man3/sys_nerr.3
new file mode 100644
index 000000000..837f1a191
--- /dev/null
+++ b/man/man3/sys_nerr.3
@@ -0,0 +1 @@
+.so man3/perror.3
diff --git a/man/man3/sys_siglist.3 b/man/man3/sys_siglist.3
new file mode 100644
index 000000000..f64f75692
--- /dev/null
+++ b/man/man3/sys_siglist.3
@@ -0,0 +1 @@
+.so man3/strsignal.3
diff --git a/man/man3/sysconf.3 b/man/man3/sysconf.3
new file mode 100644
index 000000000..1010caa8c
--- /dev/null
+++ b/man/man3/sysconf.3
@@ -0,0 +1,390 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 17:51:42 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Tue Aug 17 11:42:20 1999 by Ariel Scolnicov (ariels@compugen.co.il)
+.TH sysconf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysconf \- get configuration information at run time
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "long sysconf(int " "name" );
+.fi
+.SH DESCRIPTION
+POSIX allows an application to test at compile or run time
+whether certain options are supported, or what the value is
+of certain configurable constants or limits.
+.P
+At compile time this is done by including
+.I <unistd.h>
+and/or
+.I <limits.h>
+and testing the value of certain macros.
+.P
+At run time, one can ask for numerical values using the present function
+.BR sysconf ().
+One can ask for numerical values that may depend
+on the filesystem in which a file resides using
+.BR fpathconf (3)
+and
+.BR pathconf (3).
+One can ask for string values using
+.BR confstr (3).
+.P
+The values obtained from these functions are system configuration constants.
+They do not change during the lifetime of a process.
+.\" except that sysconf(_SC_OPEN_MAX) may change answer after a call
+.\" to setrlimit( ) which changes the RLIMIT_NOFILE soft limit
+.P
+For options, typically, there is a constant
+.B _POSIX_FOO
+that may be defined in
+.IR <unistd.h> .
+If it is undefined, one should ask at run time.
+If it is defined to \-1, then the option is not supported.
+If it is defined to 0, then relevant functions and headers exist,
+but one has to ask at run time what degree of support is available.
+If it is defined to a value other than \-1 or 0, then the option is
+supported.
+Usually the value (such as 200112L) indicates the year and month
+of the POSIX revision describing the option.
+glibc uses the value 1
+to indicate support as long as the POSIX revision has not been published yet.
+.\" and 999 to indicate support for options no longer present in the latest
+.\" standard. (?)
+The
+.BR sysconf ()
+argument will be
+.BR _SC_FOO .
+For a list of options, see
+.BR posixoptions (7).
+.P
+For variables or limits, typically, there is a constant
+.BR _FOO ,
+maybe defined in
+.IR <limits.h> ,
+or
+.BR _POSIX_FOO ,
+maybe defined in
+.IR <unistd.h> .
+The constant will not be defined if the limit is unspecified.
+If the constant is defined, it gives a guaranteed value, and
+a greater value might actually be supported.
+If an application wants to take advantage of values which may change
+between systems, a call to
+.BR sysconf ()
+can be made.
+The
+.BR sysconf ()
+argument will be
+.BR _SC_FOO .
+.SS POSIX.1 variables
+We give the name of the variable, the name of the
+.BR sysconf ()
+argument used to inquire about its value,
+and a short description.
+.P
+First, the POSIX.1 compatible values.
+.\" [for the moment: only the things that are unconditionally present]
+.\" .TP
+.\" .BR AIO_LISTIO_MAX " - " _SC_AIO_LISTIO_MAX
+.\" (if _POSIX_ASYNCHRONOUS_IO)
+.\" Maximum number of I/O operations in a single list I/O call.
+.\" Must not be less than _POSIX_AIO_LISTIO_MAX.
+.\" .TP
+.\" .BR AIO_MAX " - " _SC_AIO_MAX
+.\" (if _POSIX_ASYNCHRONOUS_IO)
+.\" Maximum number of outstanding asynchronous I/O operations.
+.\" Must not be less than _POSIX_AIO_MAX.
+.\" .TP
+.\" .BR AIO_PRIO_DELTA_MAX " - " _SC_AIO_PRIO_DELTA_MAX
+.\" (if _POSIX_ASYNCHRONOUS_IO)
+.\" The maximum amount by which a process can decrease its
+.\" asynchronous I/O priority level from its own scheduling priority.
+.\" Must be nonnegative.
+.TP
+.BR ARG_MAX " - " _SC_ARG_MAX
+The maximum length of the arguments to the
+.BR exec (3)
+family of functions.
+Must not be less than
+.B _POSIX_ARG_MAX
+(4096).
+.TP
+.BR CHILD_MAX " - " _SC_CHILD_MAX
+The maximum number of simultaneous processes per user ID.
+Must not be less than
+.B _POSIX_CHILD_MAX
+(25).
+.TP
+.BR HOST_NAME_MAX " - " _SC_HOST_NAME_MAX
+Maximum length of a hostname, not including the terminating null byte,
+as returned by
+.BR gethostname (2).
+Must not be less than
+.B _POSIX_HOST_NAME_MAX
+(255).
+.TP
+.BR LOGIN_NAME_MAX " - " _SC_LOGIN_NAME_MAX
+Maximum length of a login name, including the terminating null byte.
+Must not be less than
+.B _POSIX_LOGIN_NAME_MAX
+(9).
+.TP
+.BR NGROUPS_MAX " - " _SC_NGROUPS_MAX
+Maximum number of supplementary group IDs.
+.TP
+.BR "" "clock ticks - " _SC_CLK_TCK
+The number of clock ticks per second.
+The corresponding variable is obsolete.
+It was of course called
+.BR CLK_TCK .
+(Note: the macro
+.B CLOCKS_PER_SEC
+does not give information: it must equal 1000000.)
+.TP
+.BR OPEN_MAX " - " _SC_OPEN_MAX
+The maximum number of files that a process can have open at any time.
+Must not be less than
+.B _POSIX_OPEN_MAX
+(20).
+.TP
+.BR PAGESIZE " - " _SC_PAGESIZE
+Size of a page in bytes.
+Must not be less than 1.
+.TP
+.BR PAGE_SIZE " - " _SC_PAGE_SIZE
+A synonym for
+.BR PAGESIZE / _SC_PAGESIZE .
+(Both
+.B PAGESIZE
+and
+.B PAGE_SIZE
+are specified in POSIX.)
+.TP
+.BR RE_DUP_MAX " - " _SC_RE_DUP_MAX
+The number of repeated occurrences of a BRE permitted by
+.BR regexec (3)
+and
+.BR regcomp (3).
+Must not be less than
+.B _POSIX2_RE_DUP_MAX
+(255).
+.TP
+.BR STREAM_MAX " - " _SC_STREAM_MAX
+The maximum number of streams that a process can have open at any
+time.
+If defined, it has the same value as the standard C macro
+.BR FOPEN_MAX .
+Must not be less than
+.B _POSIX_STREAM_MAX
+(8).
+.TP
+.BR SYMLOOP_MAX " - " _SC_SYMLOOP_MAX
+The maximum number of symbolic links seen in a pathname before resolution
+returns
+.BR ELOOP .
+Must not be less than
+.B _POSIX_SYMLOOP_MAX
+(8).
+.TP
+.BR TTY_NAME_MAX " - " _SC_TTY_NAME_MAX
+The maximum length of terminal device name,
+including the terminating null byte.
+Must not be less than
+.B _POSIX_TTY_NAME_MAX
+(9).
+.TP
+.BR TZNAME_MAX " - " _SC_TZNAME_MAX
+The maximum number of bytes in a timezone name.
+Must not be less than
+.B _POSIX_TZNAME_MAX
+(6).
+.TP
+.BR _POSIX_VERSION " - " _SC_VERSION
+indicates the year and month the POSIX.1 standard was approved in the
+format
+.BR YYYYMML ;
+the value
+.B 199009L
+indicates the Sept. 1990 revision.
+.SS POSIX.2 variables
+Next, the POSIX.2 values, giving limits for utilities.
+.TP
+.BR BC_BASE_MAX " - " _SC_BC_BASE_MAX
+indicates the maximum
+.I obase
+value accepted by the
+.BR bc (1)
+utility.
+.TP
+.BR BC_DIM_MAX " - " _SC_BC_DIM_MAX
+indicates the maximum value of elements permitted in an array by
+.BR bc (1).
+.TP
+.BR BC_SCALE_MAX " - " _SC_BC_SCALE_MAX
+indicates the maximum
+.I scale
+value allowed by
+.BR bc (1).
+.TP
+.BR BC_STRING_MAX " - " _SC_BC_STRING_MAX
+indicates the maximum length of a string accepted by
+.BR bc (1).
+.TP
+.BR COLL_WEIGHTS_MAX " - " _SC_COLL_WEIGHTS_MAX
+indicates the maximum numbers of weights that can be assigned to an
+entry of the
+.B LC_COLLATE order
+keyword in the locale definition file.
+.TP
+.BR EXPR_NEST_MAX " - " _SC_EXPR_NEST_MAX
+is the maximum number of expressions which can be nested within
+parentheses by
+.BR expr (1).
+.TP
+.BR LINE_MAX " - " _SC_LINE_MAX
+The maximum length of a utility's input line, either from
+standard input or from a file.
+This includes space for a trailing
+newline.
+.TP
+.BR RE_DUP_MAX " - " _SC_RE_DUP_MAX
+The maximum number of repeated occurrences of a regular expression when
+the interval notation
+.B \e{m,n\e}
+is used.
+.TP
+.BR POSIX2_VERSION " - " _SC_2_VERSION
+indicates the version of the POSIX.2 standard in the format of
+YYYYMML.
+.TP
+.BR POSIX2_C_DEV " - " _SC_2_C_DEV
+indicates whether the POSIX.2 C language development facilities are
+supported.
+.TP
+.BR POSIX2_FORT_DEV " - " _SC_2_FORT_DEV
+indicates whether the POSIX.2 FORTRAN development utilities are
+supported.
+.TP
+.BR POSIX2_FORT_RUN " - " _SC_2_FORT_RUN
+indicates whether the POSIX.2 FORTRAN run-time utilities are supported.
+.TP
+.BR _POSIX2_LOCALEDEF " - " _SC_2_LOCALEDEF
+indicates whether the POSIX.2 creation of locales via
+.BR localedef (1)
+is supported.
+.TP
+.BR POSIX2_SW_DEV " - " _SC_2_SW_DEV
+indicates whether the POSIX.2 software development utilities option is
+supported.
+.P
+These values also exist, but may not be standard.
+.TP
+.BR "" " - " _SC_PHYS_PAGES
+The number of pages of physical memory.
+Note that it is possible
+for the product of this value and the value of
+.B _SC_PAGESIZE
+to overflow.
+.TP
+.BR "" " - " _SC_AVPHYS_PAGES
+The number of currently available pages of physical memory.
+.TP
+.BR "" " - " _SC_NPROCESSORS_CONF
+The number of processors configured.
+See also
+.BR get_nprocs_conf (3).
+.TP
+.BR "" " - " _SC_NPROCESSORS_ONLN
+The number of processors currently online (available).
+See also
+.BR get_nprocs_conf (3).
+.SH RETURN VALUE
+The return value of
+.BR sysconf ()
+is one of the following:
+.IP \[bu] 3
+On error, \-1 is returned and
+.I errno
+is set to indicate the error
+(for example,
+.BR EINVAL ,
+indicating that
+.I name
+is invalid).
+.IP \[bu]
+If
+.I name
+corresponds to a maximum or minimum limit, and that limit is indeterminate,
+\-1 is returned and
+.I errno
+is not changed.
+(To distinguish an indeterminate limit from an error, set
+.I errno
+to zero before the call, and then check whether
+.I errno
+is nonzero when \-1 is returned.)
+.IP \[bu]
+If
+.I name
+corresponds to an option,
+a positive value is returned if the option is supported,
+and \-1 is returned if the option is not supported.
+.IP \[bu]
+Otherwise,
+the current value of the option or limit is returned.
+This value will not be more restrictive than
+the corresponding value that was described to the application in
+.I <unistd.h>
+or
+.I <limits.h>
+when the application was compiled.
+.SH ERRORS
+.TP
+.B EINVAL
+.I name
+is invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sysconf ()
+T}	Thread safety	MT-Safe env
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH BUGS
+It is difficult to use
+.B ARG_MAX
+because it is not specified how much of the argument space for
+.BR exec (3)
+is consumed by the user's environment variables.
+.P
+Some returned values may be huge; they are not suitable for allocating
+memory.
+.SH SEE ALSO
+.BR bc (1),
+.BR expr (1),
+.BR getconf (1),
+.BR locale (1),
+.BR confstr (3),
+.BR fpathconf (3),
+.BR pathconf (3),
+.BR posixoptions (7)
diff --git a/man/man3/syslog.3 b/man/man3/syslog.3
new file mode 100644
index 000000000..5d83c35f8
--- /dev/null
+++ b/man/man3/syslog.3
@@ -0,0 +1,359 @@
+'\" t
+.\" Written  Feb 1994 by Steve Greenland (stevegr@neosoft.com)
+.\" and Copyright 2001, 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Updated 1999.12.19 by Karl M. Hegbloom <karlheg@debian.org>
+.\"
+.\" Updated 13 Oct 2001, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added description of vsyslog
+.\"	Added descriptions of LOG_ODELAY and LOG_NOWAIT
+.\"	Added brief description of facility and option arguments
+.\"	Added CONFORMING TO section
+.\" 2001-10-13, aeb, minor changes
+.\" Modified 13 Dec 2001, Martin Schulze <joey@infodrom.org>
+.\" Modified 3 Jan 2002, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH syslog 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+closelog, openlog, syslog, vsyslog \- send messages to the system logger
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <syslog.h>
+.P
+.BI "void openlog(const char *" ident ", int " option ", int " facility );
+.BI "void syslog(int " priority ", const char *" format ", ...);"
+.B "void closelog(void);"
+.P
+.BI "void vsyslog(int " priority ", const char *" format ", va_list " ap );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR vsyslog ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.SS openlog()
+.BR openlog ()
+opens a connection to the system logger for a program.
+.P
+The string pointed to by
+.I ident
+is prepended to every message, and is typically set to the program name.
+If
+.I ident
+is NULL, the program name is used.
+(POSIX.1-2008 does not specify the behavior when
+.I ident
+is NULL.)
+.P
+The
+.I option
+argument specifies flags which control the operation of
+.BR openlog ()
+and subsequent calls to
+.BR syslog ().
+The
+.I facility
+argument establishes a default to be used if
+none is specified in subsequent calls to
+.BR syslog ().
+The values that may be specified for
+.I option
+and
+.I facility
+are described below.
+.P
+The use of
+.BR openlog ()
+is optional; it will automatically be called by
+.BR syslog ()
+if necessary, in which case
+.I ident
+will default to NULL.
+.\"
+.SS syslog() and vsyslog()
+.BR syslog ()
+generates a log message, which will be distributed by
+.BR syslogd (8).
+.P
+The
+.I priority
+argument is formed by ORing together a
+.I facility
+value and a
+.I level
+value (described below).
+If no
+.I facility
+value is ORed into
+.IR priority ,
+then the default value set by
+.BR openlog ()
+is used, or, if there was no preceding
+.BR openlog ()
+call, a default of
+.B LOG_USER
+is employed.
+.P
+The remaining arguments are a
+.IR format ,
+as in
+.BR printf (3),
+and any arguments required by the
+.IR format ,
+except that the two-character sequence
+.B %m
+will be replaced by
+the error message string
+.IR strerror ( errno ).
+The format string need not include a terminating newline character.
+.P
+The function
+.BR vsyslog ()
+performs the same task as
+.BR syslog ()
+with the difference that it takes a set of arguments which have
+been obtained using the
+.BR stdarg (3)
+variable argument list macros.
+.\"
+.SS closelog()
+.BR closelog ()
+closes the file descriptor being used to write to the system logger.
+The use of
+.BR closelog ()
+is optional.
+.\"
+.SS Values for \fIoption\fP
+The
+.I option
+argument to
+.BR openlog ()
+is a bit mask constructed by ORing together any of the following values:
+.TP 15
+.B LOG_CONS
+Write directly to the system console if there is an error while sending to
+the system logger.
+.TP
+.B LOG_NDELAY
+Open the connection immediately (normally, the connection is opened when
+the first message is logged).
+This may be useful, for example, if a subsequent
+.BR chroot (2)
+would make the pathname used internally by the logging facility unreachable.
+.TP
+.B LOG_NOWAIT
+Don't wait for child processes that may have been created while logging
+the message.
+(The GNU C library does not create a child process, so this
+option has no effect on Linux.)
+.TP
+.B LOG_ODELAY
+The converse of
+.BR LOG_NDELAY ;
+opening of the connection is delayed until
+.BR syslog ()
+is called.
+(This is the default, and need not be specified.)
+.TP
+.B LOG_PERROR
+(Not in POSIX.1-2001 or POSIX.1-2008.)
+Also log the message to
+.IR stderr .
+.TP
+.B LOG_PID
+Include the caller's PID with each message.
+.\"
+.SS Values for \fIfacility\fP
+The
+.I facility
+argument is used to specify what type of program is logging the message.
+This lets the configuration file specify that messages from different
+facilities will be handled differently.
+.TP 15
+.B LOG_AUTH
+security/authorization messages
+.TP
+.B LOG_AUTHPRIV
+security/authorization messages (private)
+.TP
+.B LOG_CRON
+clock daemon
+.RB ( cron " and " at )
+.TP
+.B LOG_DAEMON
+system daemons without separate facility value
+.TP
+.B LOG_FTP
+ftp daemon
+.TP
+.B LOG_KERN
+kernel messages (these can't be generated from user processes)
+.\" LOG_KERN has the value 0; if used as a facility, zero translates to:
+.\" "use the default facility".
+.TP
+.BR LOG_LOCAL0 " through " LOG_LOCAL7
+reserved for local use
+.TP
+.B LOG_LPR
+line printer subsystem
+.TP
+.B LOG_MAIL
+mail subsystem
+.TP
+.B LOG_NEWS
+USENET news subsystem
+.TP
+.B LOG_SYSLOG
+messages generated internally by
+.BR syslogd (8)
+.TP
+.BR LOG_USER " (default)"
+generic user-level messages
+.TP
+.B LOG_UUCP
+UUCP subsystem
+.\"
+.SS Values for \fIlevel\fP
+This determines the importance of the message.
+The levels are, in order of decreasing importance:
+.TP 15
+.B LOG_EMERG
+system is unusable
+.TP
+.B LOG_ALERT
+action must be taken immediately
+.TP
+.B LOG_CRIT
+critical conditions
+.TP
+.B LOG_ERR
+error conditions
+.TP
+.B LOG_WARNING
+warning conditions
+.TP
+.B LOG_NOTICE
+normal, but significant, condition
+.TP
+.B LOG_INFO
+informational message
+.TP
+.B LOG_DEBUG
+debug-level message
+.P
+The function
+.BR setlogmask (3)
+can be used to restrict logging to specified levels only.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR openlog (),
+.BR closelog ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR syslog (),
+.BR vsyslog ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+.TP
+.BR syslog ()
+.TQ
+.BR openlog ()
+.TQ
+.BR closelog ()
+POSIX.1-2008.
+.TP
+.BR vsyslog ()
+None.
+.SH HISTORY
+.TP
+.BR syslog ()
+4.2BSD, SUSv2, POSIX.1-2001.
+.TP
+.BR openlog ()
+.TQ
+.BR closelog ()
+4.3BSD, SUSv2, POSIX.1-2001.
+.\" .SH HISTORY
+.\" 4.3BSD documents
+.\" .BR setlogmask ().
+.TP
+.BR vsyslog ()
+4.3BSD-Reno.
+.\" Of course early v* functions used the
+.\" .I <varargs.h>
+.\" mechanism, which is not compatible with
+.\" .IR <stdarg.h> .
+.P
+POSIX.1-2001 specifies only the
+.B LOG_USER
+and
+.B LOG_LOCAL*
+values for
+.IR facility .
+However, with the exception of
+.B LOG_AUTHPRIV
+and
+.BR LOG_FTP ,
+the other
+.I facility
+values appear on most UNIX systems.
+.P
+The
+.B LOG_PERROR
+value for
+.I option
+is not specified by POSIX.1-2001 or POSIX.1-2008, but is available
+in most versions of UNIX.
+.SH NOTES
+The argument
+.I ident
+in the call of
+.BR openlog ()
+is probably stored as-is.
+Thus, if the string it points to
+is changed,
+.BR syslog ()
+may start prepending the changed string, and if the string
+it points to ceases to exist, the results are undefined.
+Most portable is to use a string constant.
+.P
+Never pass a string with user-supplied data as a format,
+use the following instead:
+.P
+.in +4n
+.EX
+syslog(priority, "%s", string);
+.EE
+.in
+.SH SEE ALSO
+.BR journalctl (1),
+.BR logger (1),
+.BR setlogmask (3),
+.BR syslog.conf (5),
+.BR syslogd (8)
diff --git a/man/man3/system.3 b/man/man3/system.3
new file mode 100644
index 000000000..fb5d0af6b
--- /dev/null
+++ b/man/man3/system.3
@@ -0,0 +1,269 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright (c) 2014 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 17:51:15 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 11 May 1998 by Joseph S. Myers (jsm28@cam.ac.uk)
+.\" Modified 14 May 2001, 23 Sep 2001 by aeb
+.\" 2004-12-20, mtk
+.\"
+.TH system 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+system \- execute a shell command
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int system(const char *" "command" );
+.fi
+.SH DESCRIPTION
+The
+.BR system ()
+library function behaves as if it used
+.BR fork (2)
+to create a child process that executed the shell command specified in
+.I command
+using
+.BR execl (3)
+as follows:
+.P
+.in +4n
+.EX
+execl("/bin/sh", "sh", "\-c", command, (char *) NULL);
+.EE
+.in
+.P
+.BR system ()
+returns after the command has been completed.
+.P
+During execution of the command,
+.B SIGCHLD
+will be blocked, and
+.B SIGINT
+and
+.B SIGQUIT
+will be ignored, in the process that calls
+.BR system ().
+(These signals will be handled according to their defaults inside
+the child process that executes
+.IR command .)
+.P
+If
+.I command
+is NULL, then
+.BR system ()
+returns a status indicating whether a shell is available on the system.
+.SH RETURN VALUE
+The return value of
+.BR system ()
+is one of the following:
+.IP \[bu] 3
+If
+.I command
+is NULL, then a nonzero value if a shell is available,
+or 0 if no shell is available.
+.IP \[bu]
+If a child process could not be created,
+or its status could not be retrieved,
+the return value is \-1 and
+.I errno
+is set to indicate the error.
+.IP \[bu]
+If a shell could not be executed in the child process,
+then the return value is as though the child shell terminated by calling
+.BR _exit (2)
+with the status 127.
+.IP \[bu]
+If all system calls succeed,
+then the return value is the termination status of the child shell
+used to execute
+.IR command .
+(The termination status of a shell is the termination status of
+the last command it executes.)
+.P
+In the last two cases,
+the return value is a "wait status" that can be examined using
+the macros described in
+.BR waitpid (2).
+(i.e.,
+.BR WIFEXITED (),
+.BR WEXITSTATUS (),
+and so on).
+.P
+.BR system ()
+does not affect the wait status of any other children.
+.SH ERRORS
+.BR system ()
+can fail with any of the same errors as
+.BR fork (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR system ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89.
+.SH NOTES
+.BR system ()
+provides simplicity and convenience:
+it handles all of the details of calling
+.BR fork (2),
+.BR execl (3),
+and
+.BR waitpid (2),
+as well as the necessary manipulations of signals;
+in addition,
+the shell performs the usual substitutions and I/O redirections for
+.IR command .
+The main cost of
+.BR system ()
+is inefficiency:
+additional system calls are required to create the process that
+runs the shell and to execute the shell.
+.P
+If the
+.B _XOPEN_SOURCE
+feature test macro is defined
+(before including
+.I any
+header files),
+then the macros described in
+.BR waitpid (2)
+.RB ( WEXITSTATUS (),
+etc.) are made available when including
+.IR <stdlib.h> .
+.P
+As mentioned,
+.BR system ()
+ignores
+.B SIGINT
+and
+.BR SIGQUIT .
+This may make programs that call it
+from a loop uninterruptible, unless they take care themselves
+to check the exit status of the child.
+For example:
+.P
+.in +4n
+.EX
+while (something) {
+    int ret = system("foo");
+\&
+    if (WIFSIGNALED(ret) &&
+        (WTERMSIG(ret) == SIGINT || WTERMSIG(ret) == SIGQUIT))
+            break;
+}
+.EE
+.in
+.P
+According to POSIX.1, it is unspecified whether handlers registered using
+.BR pthread_atfork (3)
+are called during the execution of
+.BR system ().
+In the glibc implementation, such handlers are not called.
+.P
+Before glibc 2.1.3, the check for the availability of
+.I /bin/sh
+was not actually performed if
+.I command
+was NULL; instead it was always assumed to be available, and
+.BR system ()
+always returned 1 in this case.
+Since glibc 2.1.3, this check is performed because, even though
+POSIX.1-2001 requires a conforming implementation to provide
+a shell, that shell may not be available or executable if
+the calling program has previously called
+.BR chroot (2)
+(which is not specified by POSIX.1-2001).
+.P
+It is possible for the shell command to terminate with a status of 127,
+which yields a
+.BR system ()
+return value that is indistinguishable from the case
+where a shell could not be executed in the child process.
+.\"
+.SS Caveats
+Do not use
+.BR system ()
+from a privileged program
+(a set-user-ID or set-group-ID program, or a program with capabilities)
+because strange values for some environment variables
+might be used to subvert system integrity.
+For example,
+.B PATH
+could be manipulated so that an arbitrary program
+is executed with privilege.
+Use the
+.BR exec (3)
+family of functions instead, but not
+.BR execlp (3)
+or
+.BR execvp (3)
+(which also use the
+.B PATH
+environment variable to search for an executable).
+.P
+.BR system ()
+will not, in fact, work properly from programs with set-user-ID or
+set-group-ID privileges on systems on which
+.I /bin/sh
+is bash version 2: as a security measure, bash 2 drops privileges on startup.
+(Debian uses a different shell,
+.BR dash (1),
+which does not do this when invoked as
+.BR sh .)
+.P
+Any user input that is employed as part of
+.I command
+should be
+.I carefully
+sanitized, to ensure that unexpected shell commands or command options
+are not executed.
+Such risks are especially grave when using
+.BR system ()
+from a privileged program.
+.SH BUGS
+.\" [BUG 211029](https://bugzilla.kernel.org/show_bug.cgi?id=211029)
+.\" [glibc bug](https://sourceware.org/bugzilla/show_bug.cgi?id=27143)
+.\" [POSIX bug](https://www.austingroupbugs.net/view.php?id=1440)
+If the command name starts with a hyphen,
+.BR sh (1)
+interprets the command name as an option,
+and the behavior is undefined.
+(See the
+.B \-c
+option to
+.BR sh (1).)
+To work around this problem,
+prepend the command with a space as in the following call:
+.P
+.in +4n
+.EX
+    system(" \-unfortunate\-command\-name");
+.EE
+.in
+.SH SEE ALSO
+.BR sh (1),
+.BR execve (2),
+.BR fork (2),
+.BR sigaction (2),
+.BR sigprocmask (2),
+.BR wait (2),
+.BR exec (3),
+.BR signal (7)
diff --git a/man/man3/sysv_signal.3 b/man/man3/sysv_signal.3
new file mode 100644
index 000000000..d942ad751
--- /dev/null
+++ b/man/man3/sysv_signal.3
@@ -0,0 +1,90 @@
+'\" t
+.\" Copyright (c) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sysv_signal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysv_signal \- signal handling with System V semantics
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <signal.h>
+.P
+.B typedef void (*sighandler_t)(int);
+.P
+.BI "sighandler_t sysv_signal(int " signum ", sighandler_t " handler );
+.fi
+.SH DESCRIPTION
+The
+.BR sysv_signal ()
+function takes the same arguments, and performs the same task, as
+.BR signal (2).
+.P
+However
+.BR sysv_signal ()
+provides the System V unreliable signal semantics, that is:
+a) the disposition of the signal is reset to the default
+when the handler is invoked;
+b) delivery of further instances of the signal is not blocked while
+the signal handler is executing; and
+c) if the handler interrupts (certain) blocking system calls,
+then the system call is not automatically restarted.
+.SH RETURN VALUE
+The
+.BR sysv_signal ()
+function returns the previous value of the signal handler, or
+.B SIG_ERR
+on error.
+.SH ERRORS
+As for
+.BR signal (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR sysv_signal ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Use of
+.BR sysv_signal ()
+should be avoided; use
+.BR sigaction (2)
+instead.
+.P
+On older Linux systems,
+.BR sysv_signal ()
+and
+.BR signal (2)
+were equivalent.
+But on newer systems,
+.BR signal (2)
+provides reliable signal semantics; see
+.BR signal (2)
+for details.
+.P
+The use of
+.I sighandler_t
+is a GNU extension;
+this type is defined only if
+the
+.B _GNU_SOURCE
+feature test macro is defined.
+.SH STANDARDS
+None.
+.SH SEE ALSO
+.BR sigaction (2),
+.BR signal (2),
+.BR bsd_signal (3),
+.BR signal (7)
diff --git a/man/man3/tailq.3 b/man/man3/tailq.3
new file mode 100644
index 000000000..ced7b5408
--- /dev/null
+++ b/man/man3/tailq.3
@@ -0,0 +1,397 @@
+.\" Copyright (c) 1993
+.\"    The Regents of the University of California.  All rights reserved.
+.\" and Copyright (c) 2020 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"
+.TH TAILQ 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+TAILQ_CONCAT,
+TAILQ_EMPTY,
+TAILQ_ENTRY,
+TAILQ_FIRST,
+TAILQ_FOREACH,
+.\"TAILQ_FOREACH_FROM,
+.\"TAILQ_FOREACH_FROM_SAFE,
+TAILQ_FOREACH_REVERSE,
+.\"TAILQ_FOREACH_REVERSE_FROM,
+.\"TAILQ_FOREACH_REVERSE_FROM_SAFE,
+.\"TAILQ_FOREACH_REVERSE_SAFE,
+.\"TAILQ_FOREACH_SAFE,
+TAILQ_HEAD,
+TAILQ_HEAD_INITIALIZER,
+TAILQ_INIT,
+TAILQ_INSERT_AFTER,
+TAILQ_INSERT_BEFORE,
+TAILQ_INSERT_HEAD,
+TAILQ_INSERT_TAIL,
+TAILQ_LAST,
+TAILQ_NEXT,
+TAILQ_PREV,
+TAILQ_REMOVE
+.\"TAILQ_SWAP
+\- implementation of a doubly linked tail queue
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/queue.h>
+.P
+.B TAILQ_ENTRY(TYPE);
+.P
+.B TAILQ_HEAD(HEADNAME, TYPE);
+.BI "TAILQ_HEAD TAILQ_HEAD_INITIALIZER(TAILQ_HEAD " head );
+.BI "void TAILQ_INIT(TAILQ_HEAD *" head );
+.P
+.BI "int TAILQ_EMPTY(TAILQ_HEAD *" head );
+.P
+.BI "void TAILQ_INSERT_HEAD(TAILQ_HEAD *" head ,
+.BI "                         struct TYPE *" elm ", TAILQ_ENTRY " NAME );
+.BI "void TAILQ_INSERT_TAIL(TAILQ_HEAD *" head ,
+.BI "                         struct TYPE *" elm ", TAILQ_ENTRY " NAME );
+.BI "void TAILQ_INSERT_BEFORE(struct TYPE *" listelm ,
+.BI "                         struct TYPE *" elm ", TAILQ_ENTRY " NAME );
+.BI "void TAILQ_INSERT_AFTER(TAILQ_HEAD *" head ", struct TYPE *" listelm ,
+.BI "                         struct TYPE *" elm ", TAILQ_ENTRY " NAME );
+.P
+.BI "struct TYPE *TAILQ_FIRST(TAILQ_HEAD *" head );
+.BI "struct TYPE *TAILQ_LAST(TAILQ_HEAD *" head ", HEADNAME);"
+.BI "struct TYPE *TAILQ_PREV(struct TYPE *" elm ", HEADNAME, TAILQ_ENTRY " NAME );
+.BI "struct TYPE *TAILQ_NEXT(struct TYPE *" elm ", TAILQ_ENTRY " NAME );
+.P
+.BI "TAILQ_FOREACH(struct TYPE *" var ", TAILQ_HEAD *" head ,
+.BI "                         TAILQ_ENTRY " NAME );
+.\" .BI "TAILQ_FOREACH_FROM(struct TYPE *" var ", TAILQ_HEAD *" head ,
+.\" .BI "                                TAILQ_ENTRY " NAME );
+.BI "TAILQ_FOREACH_REVERSE(struct TYPE *" var ", TAILQ_HEAD *" head ", HEADNAME,"
+.BI "                         TAILQ_ENTRY " NAME );
+.\" .BI "TAILQ_FOREACH_REVERSE_FROM(struct TYPE *" var ", TAILQ_HEAD *" head ", HEADNAME,"
+.\" .BI "                                TAILQ_ENTRY " NAME );
+.\" .P
+.\" .BI "TAILQ_FOREACH_SAFE(struct TYPE *" var ", TAILQ_HEAD *" head ,
+.\" .BI "                                TAILQ_ENTRY " NAME ,
+.\" .BI "                                struct TYPE *" temp_var );
+.\" .BI "TAILQ_FOREACH_FROM_SAFE(struct TYPE *" var ", TAILQ_HEAD *" head ,
+.\" .BI "                                TAILQ_ENTRY " NAME ,
+.\" .BI "                                struct TYPE *" temp_var );
+.\" .BI "TAILQ_FOREACH_REVERSE_SAFE(struct TYPE *" var ", TAILQ_HEAD *" head ,
+.\" .BI "                                HEADNAME, TAILQ_ENTRY " NAME ,
+.\" .BI "                                struct TYPE *" temp_var );
+.\" .BI "TAILQ_FOREACH_REVERSE_FROM_SAFE(struct TYPE *" var ", TAILQ_HEAD *" head ,
+.\" .BI "                                HEADNAME, TAILQ_ENTRY " NAME ,
+.\" .BI "                                struct TYPE *" temp_var );
+.P
+.BI "void TAILQ_REMOVE(TAILQ_HEAD *" head ", struct TYPE *" elm ,
+.BI "                         TAILQ_ENTRY " NAME );
+.P
+.BI "void TAILQ_CONCAT(TAILQ_HEAD *" head1 ", TAILQ_HEAD *" head2 ,
+.BI "                         TAILQ_ENTRY " NAME );
+.\" .BI "void TAILQ_SWAP(TAILQ_HEAD *" head1 ", TAILQ_HEAD *" head2 ", TYPE,"
+.\" .BI "                                TAILQ_ENTRY " NAME );
+.fi
+.SH DESCRIPTION
+These macros define and operate on doubly linked tail queues.
+.P
+In the macro definitions,
+.I TYPE
+is the name of a user defined structure,
+that must contain a field of type
+.IR TAILQ_ENTRY ,
+named
+.IR NAME .
+The argument
+.I HEADNAME
+is the name of a user defined structure that must be declared
+using the macro
+.BR TAILQ_HEAD ().
+.SS Creation
+A tail queue is headed by a structure defined by the
+.BR TAILQ_HEAD ()
+macro.
+This structure contains a pair of pointers,
+one to the first element in the queue
+and the other to the last element in the queue.
+The elements are doubly linked
+so that an arbitrary element can be removed without traversing the queue.
+New elements can be added to the queue
+after an existing element,
+before an existing element,
+at the head of the queue,
+or at the end of the queue.
+A
+.I TAILQ_HEAD
+structure is declared as follows:
+.P
+.in +4
+.EX
+TAILQ_HEAD(HEADNAME, TYPE) head;
+.EE
+.in
+.P
+where
+.I struct HEADNAME
+is the structure to be defined, and
+.I struct TYPE
+is the type of the elements to be linked into the queue.
+A pointer to the head of the queue can later be declared as:
+.P
+.in +4
+.EX
+struct HEADNAME *headp;
+.EE
+.in
+.P
+(The names
+.I head
+and
+.I headp
+are user selectable.)
+.P
+.BR TAILQ_ENTRY ()
+declares a structure that connects the elements in the queue.
+.P
+.BR TAILQ_HEAD_INITIALIZER ()
+evaluates to an initializer for the queue
+.IR head .
+.P
+.BR TAILQ_INIT ()
+initializes the queue referenced by
+.P
+.BR TAILQ_EMPTY ()
+evaluates to true if there are no items on the queue.
+.IR head .
+.SS Insertion
+.BR TAILQ_INSERT_HEAD ()
+inserts the new element
+.I elm
+at the head of the queue.
+.P
+.BR TAILQ_INSERT_TAIL ()
+inserts the new element
+.I elm
+at the end of the queue.
+.P
+.BR TAILQ_INSERT_BEFORE ()
+inserts the new element
+.I elm
+before the element
+.IR listelm .
+.P
+.BR TAILQ_INSERT_AFTER ()
+inserts the new element
+.I elm
+after the element
+.IR listelm .
+.SS Traversal
+.BR TAILQ_FIRST ()
+returns the first item on the queue, or NULL if the queue is empty.
+.P
+.BR TAILQ_LAST ()
+returns the last item on the queue.
+If the queue is empty the return value is NULL.
+.P
+.BR TAILQ_PREV ()
+returns the previous item on the queue, or NULL if this item is the first.
+.P
+.BR TAILQ_NEXT ()
+returns the next item on the queue, or NULL if this item is the last.
+.P
+.BR TAILQ_FOREACH ()
+traverses the queue referenced by
+.I head
+in the forward direction,
+assigning each element in turn to
+.IR var .
+.I var
+is set to NULL if the loop completes normally,
+or if there were no elements.
+.\" .P
+.\" .BR TAILQ_FOREACH_FROM ()
+.\" behaves identically to
+.\" .BR TAILQ_FOREACH ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found TAILQ element and begins the loop at
+.\" .I var
+.\" instead of the first element in the TAILQ referenced by
+.\" .IR head .
+.P
+.BR TAILQ_FOREACH_REVERSE ()
+traverses the queue referenced by
+.I head
+in the reverse direction,
+assigning each element in turn to
+.IR var .
+.\" .P
+.\" .BR TAILQ_FOREACH_REVERSE_FROM ()
+.\" behaves identically to
+.\" .BR TAILQ_FOREACH_REVERSE ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found TAILQ element and begins the reverse loop at
+.\" .I var
+.\" instead of the last element in the TAILQ referenced by
+.\" .IR head .
+.\" .P
+.\" .BR TAILQ_FOREACH_SAFE ()
+.\" and
+.\" .BR TAILQ_FOREACH_REVERSE_SAFE ()
+.\" traverse the list referenced by
+.\" .I head
+.\" in the forward or reverse direction respectively,
+.\" assigning each element in turn to
+.\" .IR var .
+.\" However, unlike their unsafe counterparts,
+.\" .BR TAILQ_FOREACH ()
+.\" and
+.\" .BR TAILQ_FOREACH_REVERSE ()
+.\" permit to both remove
+.\" .I var
+.\" as well as free it from within the loop safely without interfering with the
+.\" traversal.
+.\" .P
+.\" .BR TAILQ_FOREACH_FROM_SAFE ()
+.\" behaves identically to
+.\" .BR TAILQ_FOREACH_SAFE ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found TAILQ element and begins the loop at
+.\" .I var
+.\" instead of the first element in the TAILQ referenced by
+.\" .IR head .
+.\" .P
+.\" .BR TAILQ_FOREACH_REVERSE_FROM_SAFE ()
+.\" behaves identically to
+.\" .BR TAILQ_FOREACH_REVERSE_SAFE ()
+.\" when
+.\" .I var
+.\" is NULL, else it treats
+.\" .I var
+.\" as a previously found TAILQ element and begins the reverse loop at
+.\" .I var
+.\" instead of the last element in the TAILQ referenced by
+.\" .IR head .
+.SS Removal
+.BR TAILQ_REMOVE ()
+removes the element
+.I elm
+from the queue.
+.SS Other features
+.\" .BR TAILQ_SWAP ()
+.\" swaps the contents of
+.\" .I head1
+.\" and
+.\" .IR head2 .
+.\" .P
+.BR TAILQ_CONCAT ()
+concatenates the queue headed by
+.I head2
+onto the end of the one headed by
+.I head1
+removing all entries from the former.
+.SH RETURN VALUE
+.BR TAILQ_EMPTY ()
+returns nonzero if the queue is empty,
+and zero if the queue contains at least one entry.
+.P
+.BR TAILQ_FIRST (),
+.BR TAILQ_LAST (),
+.BR TAILQ_PREV (),
+and
+.BR TAILQ_NEXT ()
+return a pointer to the first, last, previous, or next
+.I TYPE
+structure, respectively.
+.P
+.BR TAILQ_HEAD_INITIALIZER ()
+returns an initializer that can be assigned to the queue
+.IR head .
+.SH STANDARDS
+BSD.
+.SH HISTORY
+4.4BSD.
+.SH CAVEATS
+.BR TAILQ_FOREACH ()
+and
+.BR TAILQ_FOREACH_REVERSE ()
+don't allow
+.I var
+to be removed or freed within the loop,
+as it would interfere with the traversal.
+.BR TAILQ_FOREACH_SAFE ()
+and
+.BR TAILQ_FOREACH_REVERSE_SAFE (),
+which are present on the BSDs but are not present in glibc,
+fix this limitation by allowing
+.I var
+to safely be removed from the list and freed from within the loop
+without interfering with the traversal.
+.SH EXAMPLES
+.\" SRC BEGIN (tailq.c)
+.EX
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/queue.h>
+\&
+struct entry {
+    int data;
+    TAILQ_ENTRY(entry) entries;             /* Tail queue */
+};
+\&
+TAILQ_HEAD(tailhead, entry);
+\&
+int
+main(void)
+{
+    struct entry *n1, *n2, *n3, *np;
+    struct tailhead head;                   /* Tail queue head */
+    int i;
+\&
+    TAILQ_INIT(&head);                      /* Initialize the queue */
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the head */
+    TAILQ_INSERT_HEAD(&head, n1, entries);
+\&
+    n1 = malloc(sizeof(struct entry));      /* Insert at the tail */
+    TAILQ_INSERT_TAIL(&head, n1, entries);
+\&
+    n2 = malloc(sizeof(struct entry));      /* Insert after */
+    TAILQ_INSERT_AFTER(&head, n1, n2, entries);
+\&
+    n3 = malloc(sizeof(struct entry));      /* Insert before */
+    TAILQ_INSERT_BEFORE(n2, n3, entries);
+\&
+    TAILQ_REMOVE(&head, n2, entries);       /* Deletion */
+    free(n2);
+                                            /* Forward traversal */
+    i = 0;
+    TAILQ_FOREACH(np, &head, entries)
+        np\->data = i++;
+                                            /* Reverse traversal */
+    TAILQ_FOREACH_REVERSE(np, &head, tailhead, entries)
+        printf("%i\en", np\->data);
+                                            /* TailQ deletion */
+    n1 = TAILQ_FIRST(&head);
+    while (n1 != NULL) {
+        n2 = TAILQ_NEXT(n1, entries);
+        free(n1);
+        n1 = n2;
+    }
+    TAILQ_INIT(&head);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR insque (3),
+.BR queue (7)
diff --git a/man/man3/tan.3 b/man/man3/tan.3
new file mode 100644
index 000000000..f91a32208
--- /dev/null
+++ b/man/man3/tan.3
@@ -0,0 +1,146 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH tan 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tan, tanf, tanl \- tangent function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double tan(double " x );
+.BI "float tanf(float " x );
+.BI "long double tanl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR tanf (),
+.BR tanl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the tangent of
+.IR x ,
+where
+.I x
+is
+given in radians.
+.SH RETURN VALUE
+On success, these functions return the tangent of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is positive infinity or negative infinity,
+a domain error occurs,
+and a NaN is returned.
+.P
+If the correct result would overflow,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the mathematically correct sign.
+.\" I think overflow can't occur, because the closest floating-point
+.\" representation of pi/2 is still not close enough to pi/2 to
+.\" produce a large enough value to overflow.
+.\" Testing certainly seems to bear this out.  -- mtk, Jul 08
+.\"
+.\" POSIX.1 allows an optional underflow error;
+.\" glibc 2.8 doesn't do this
+.\" POSIX.1 an optional range error for subnormal x;
+.\" glibc 2.8 doesn't do this
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is an infinity
+.I errno
+is set to
+.B EDOM
+(but see BUGS).
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Range error: result overflow
+.\" Unable to test this case, since the best approximation of
+.\" pi/2 in double precision only yields a tan() value of 1.633e16.
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tan (),
+.BR tanf (),
+.BR tanl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH BUGS
+Before glibc 2.10, the glibc implementation did not set
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=6782
+.I errno
+to
+.B EDOM
+when a domain error occurred.
+.SH SEE ALSO
+.BR acos (3),
+.BR asin (3),
+.BR atan (3),
+.BR atan2 (3),
+.BR cos (3),
+.BR ctan (3),
+.BR sin (3)
diff --git a/man/man3/tanf.3 b/man/man3/tanf.3
new file mode 100644
index 000000000..58e5a1659
--- /dev/null
+++ b/man/man3/tanf.3
@@ -0,0 +1 @@
+.so man3/tan.3
diff --git a/man/man3/tanh.3 b/man/man3/tanh.3
new file mode 100644
index 000000000..8fa78e3b4
--- /dev/null
+++ b/man/man3/tanh.3
@@ -0,0 +1,105 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-07-27 by Walter Harms
+.\" 	(walter.harms@informatik.uni-oldenburg.de)
+.\"
+.TH tanh 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tanh, tanhf, tanhl \- hyperbolic tangent function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double tanh(double " x );
+.BI "float tanhf(float " x );
+.BI "long double tanhl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR tanhf (),
+.BR tanhl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+These functions return the hyperbolic tangent of
+.IR x ,
+which
+is defined mathematically as:
+.P
+.nf
+    tanh(x) = sinh(x) / cosh(x)
+.fi
+.SH RETURN VALUE
+On success, these functions return the hyperbolic tangent of
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is +0 (\-0), +0 (\-0) is returned.
+.P
+If
+.I x
+is positive infinity (negative infinity),
++1 (\-1) is returned.
+.\"
+.\" POSIX.1-2001 documents an optional range error (underflow)
+.\" for subnormal x;
+.\" glibc 2.8 does not do this.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tanh (),
+.BR tanhf (),
+.BR tanhl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The variant returning
+.I double
+also conforms to
+SVr4, 4.3BSD, C89.
+.SH SEE ALSO
+.BR acosh (3),
+.BR asinh (3),
+.BR atanh (3),
+.BR cosh (3),
+.BR ctanh (3),
+.BR sinh (3)
diff --git a/man/man3/tanhf.3 b/man/man3/tanhf.3
new file mode 100644
index 000000000..3556edba4
--- /dev/null
+++ b/man/man3/tanhf.3
@@ -0,0 +1 @@
+.so man3/tanh.3
diff --git a/man/man3/tanhl.3 b/man/man3/tanhl.3
new file mode 100644
index 000000000..3556edba4
--- /dev/null
+++ b/man/man3/tanhl.3
@@ -0,0 +1 @@
+.so man3/tanh.3
diff --git a/man/man3/tanl.3 b/man/man3/tanl.3
new file mode 100644
index 000000000..58e5a1659
--- /dev/null
+++ b/man/man3/tanl.3
@@ -0,0 +1 @@
+.so man3/tan.3
diff --git a/man/man3/tcdrain.3 b/man/man3/tcdrain.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/tcdrain.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/tcflow.3 b/man/man3/tcflow.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/tcflow.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/tcflush.3 b/man/man3/tcflush.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/tcflush.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/tcgetattr.3 b/man/man3/tcgetattr.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/tcgetattr.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/tcgetpgrp.3 b/man/man3/tcgetpgrp.3
new file mode 100644
index 000000000..e19a7760d
--- /dev/null
+++ b/man/man3/tcgetpgrp.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH tcgetpgrp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tcgetpgrp, tcsetpgrp \- get and set terminal foreground process group
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <unistd.h>"
+.P
+.BI "pid_t tcgetpgrp(int " fd );
+.BI "int tcsetpgrp(int " fd ", pid_t " pgrp );
+.fi
+.SH DESCRIPTION
+The function
+.BR tcgetpgrp ()
+returns the process group ID of the foreground process group on the
+terminal associated to
+.IR fd ,
+which must be the controlling terminal of the calling process.
+.\" The process itself may be a background process.
+.P
+The function
+.BR tcsetpgrp ()
+makes the process group with process group ID
+.I pgrp
+the foreground process group on the terminal associated to
+.IR fd ,
+which must be the controlling terminal of the calling process,
+and still be associated with its session.
+Moreover,
+.I pgrp
+must be a (nonempty) process group belonging to
+the same session as the calling process.
+.P
+If
+.BR tcsetpgrp ()
+is called by a member of a background process group in its session,
+and the calling process is not blocking or ignoring
+.BR SIGTTOU ,
+a
+.B SIGTTOU
+signal is sent to all members of this background process group.
+.SH RETURN VALUE
+When
+.I fd
+refers to the controlling terminal of the calling process,
+the function
+.BR tcgetpgrp ()
+will return the foreground process group ID of that terminal
+if there is one, and some value larger than 1 that is not
+presently a process group ID otherwise.
+When
+.I fd
+does not refer to the controlling terminal of the calling process,
+\-1 is returned, and
+.I errno
+is set to indicate the error.
+.P
+When successful,
+.BR tcsetpgrp ()
+returns 0.
+Otherwise, it returns \-1, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B EINVAL
+.I pgrp
+has an unsupported value.
+.TP
+.B ENOTTY
+The calling process does not have a controlling terminal, or
+it has one but it is not described by
+.IR fd ,
+or, for
+.BR tcsetpgrp (),
+this controlling terminal is no longer associated with the session
+of the calling process.
+.TP
+.B EPERM
+.I pgrp
+has a supported value, but is not the process group ID of a
+process in the same session as the calling process.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tcgetpgrp (),
+.BR tcsetpgrp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+These functions are implemented via the
+.B TIOCGPGRP
+and
+.B TIOCSPGRP
+ioctls.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+The ioctls appeared in 4.2BSD.
+The functions are POSIX inventions.
+.SH SEE ALSO
+.BR setpgid (2),
+.BR setsid (2),
+.BR credentials (7)
diff --git a/man/man3/tcgetsid.3 b/man/man3/tcgetsid.3
new file mode 100644
index 000000000..bc134d2e4
--- /dev/null
+++ b/man/man3/tcgetsid.3
@@ -0,0 +1,73 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH tcgetsid 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tcgetsid \- get session ID
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _XOPEN_SOURCE 500" "        /* See feature_test_macros(7) */"
+.B "#include <termios.h>"
+.P
+.BI "pid_t tcgetsid(int " fd );
+.fi
+.SH DESCRIPTION
+The function
+.BR tcgetsid ()
+returns the session ID of the current session that has the
+terminal associated to
+.I fd
+as controlling terminal.
+This terminal must be the controlling terminal of the calling process.
+.SH RETURN VALUE
+When
+.I fd
+refers to the controlling terminal of our session,
+the function
+.BR tcgetsid ()
+will return the session ID of this session.
+Otherwise, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+.I fd
+is not a valid file descriptor.
+.TP
+.B ENOTTY
+The calling process does not have a controlling terminal, or
+it has one but it is not described by
+.IR fd .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tcgetsid ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.P
+This function is implemented via the
+.B TIOCGSID
+.BR ioctl (2),
+present
+since Linux 2.1.71.
+.SH SEE ALSO
+.BR getsid (2)
diff --git a/man/man3/tcsendbreak.3 b/man/man3/tcsendbreak.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/tcsendbreak.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/tcsetattr.3 b/man/man3/tcsetattr.3
new file mode 100644
index 000000000..eb472496d
--- /dev/null
+++ b/man/man3/tcsetattr.3
@@ -0,0 +1 @@
+.so man3/termios.3
diff --git a/man/man3/tcsetpgrp.3 b/man/man3/tcsetpgrp.3
new file mode 100644
index 000000000..1a8b3604a
--- /dev/null
+++ b/man/man3/tcsetpgrp.3
@@ -0,0 +1 @@
+.so man3/tcgetpgrp.3
diff --git a/man/man3/tdelete.3 b/man/man3/tdelete.3
new file mode 100644
index 000000000..72f125195
--- /dev/null
+++ b/man/man3/tdelete.3
@@ -0,0 +1 @@
+.so man3/tsearch.3
diff --git a/man/man3/tdestroy.3 b/man/man3/tdestroy.3
new file mode 100644
index 000000000..72f125195
--- /dev/null
+++ b/man/man3/tdestroy.3
@@ -0,0 +1 @@
+.so man3/tsearch.3
diff --git a/man/man3/telldir.3 b/man/man3/telldir.3
new file mode 100644
index 000000000..55cd90317
--- /dev/null
+++ b/man/man3/telldir.3
@@ -0,0 +1,100 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 17:48:42 1993 by Rik Faith (faith@cs.unc.edu)
+.TH telldir 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+telldir \- return current location in directory stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <dirent.h>
+.P
+.BI "long telldir(DIR *" dirp );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR telldir ():
+.nf
+    _XOPEN_SOURCE
+       || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+       || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR telldir ()
+function returns the current location associated with
+the directory stream \fIdirp\fP.
+.SH RETURN VALUE
+On success, the
+.BR telldir ()
+function returns the current location
+in the directory stream.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+Invalid directory stream descriptor \fIdirp\fP.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR telldir ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.3BSD.
+.P
+Up to glibc 2.1.1, the return type of
+.BR telldir ()
+was
+.IR off_t .
+POSIX.1-2001 specifies
+.IR long ,
+and this is the type used since glibc 2.1.2.
+.P
+In early filesystems, the value returned by
+.BR telldir ()
+was a simple file offset within a directory.
+Modern filesystems use tree or hash structures, rather than flat tables,
+to represent directories.
+On such filesystems, the value returned by
+.BR telldir ()
+(and used internally by
+.BR readdir (3))
+is a "cookie" that is used by the implementation
+to derive a position within a directory.
+.\" https://lwn.net/Articles/544298/
+Application programs should treat this strictly as an opaque value, making
+.I no
+assumptions about its contents.
+.SH SEE ALSO
+.BR closedir (3),
+.BR opendir (3),
+.BR readdir (3),
+.BR rewinddir (3),
+.BR scandir (3),
+.BR seekdir (3)
diff --git a/man/man3/tempnam.3 b/man/man3/tempnam.3
new file mode 100644
index 000000000..f9821896b
--- /dev/null
+++ b/man/man3/tempnam.3
@@ -0,0 +1,175 @@
+'\" t
+.\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH tempnam 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tempnam \- create a name for a temporary file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "char *tempnam(const char *" dir ", const char *" pfx );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR tempnam ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+.I "Never use this function."
+Use
+.BR mkstemp (3)
+or
+.BR tmpfile (3)
+instead.
+.P
+The
+.BR tempnam ()
+function returns a pointer to a string that is a valid filename,
+and such that a file with this name did not exist when
+.BR tempnam ()
+checked.
+The filename suffix of the pathname generated will start with
+.I pfx
+in case
+.I pfx
+is a non-NULL string of at most five bytes.
+The directory prefix part of the pathname generated is required to
+be "appropriate" (often that at least implies writable).
+.P
+Attempts to find an appropriate directory go through the following
+steps:
+.TP 3
+a)
+In case the environment variable
+.B TMPDIR
+exists and
+contains the name of an appropriate directory, that is used.
+.TP
+b)
+Otherwise, if the
+.I dir
+argument is non-NULL and appropriate, it is used.
+.TP
+c)
+Otherwise,
+.I P_tmpdir
+(as defined in
+.IR <stdio.h> )
+is used when appropriate.
+.TP
+d)
+Finally an implementation-defined directory may be used.
+.P
+The string returned by
+.BR tempnam ()
+is allocated using
+.BR malloc (3)
+and hence should be freed by
+.BR free (3).
+.SH RETURN VALUE
+On success, the
+.BR tempnam ()
+function returns a pointer to a unique temporary filename.
+It returns NULL if a unique name cannot be generated, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Allocation of storage failed.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tempnam ()
+T}	Thread safety	MT-Safe env
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+SVr4, 4.3BSD, POSIX.1-2001.
+Obsoleted in POSIX.1-2008.
+.SH NOTES
+Although
+.BR tempnam ()
+generates names that are difficult to guess,
+it is nevertheless possible that between the time that
+.BR tempnam ()
+returns a pathname, and the time that the program opens it,
+another program might create that pathname using
+.BR open (2),
+or create it as a symbolic link.
+This can lead to security holes.
+To avoid such possibilities, use the
+.BR open (2)
+.B O_EXCL
+flag to open the pathname.
+Or better yet, use
+.BR mkstemp (3)
+or
+.BR tmpfile (3).
+.P
+SUSv2 does not mention the use of
+.BR TMPDIR ;
+glibc will use it only
+when the program is not set-user-ID.
+On SVr4, the directory used under \fBd)\fP is
+.I /tmp
+(and this is what glibc does).
+.P
+Because it dynamically allocates memory used to return the pathname,
+.BR tempnam ()
+is reentrant, and thus thread safe, unlike
+.BR tmpnam (3).
+.P
+The
+.BR tempnam ()
+function generates a different string each time it is called,
+up to
+.B TMP_MAX
+(defined in
+.IR <stdio.h> )
+times.
+If it is called more than
+.B TMP_MAX
+times,
+the behavior is implementation defined.
+.P
+.BR tempnam ()
+uses at most the first five bytes from
+.IR pfx .
+.P
+The glibc implementation of
+.BR tempnam ()
+fails with the error
+.B EEXIST
+upon failure to find a unique name.
+.SH BUGS
+The precise meaning of "appropriate" is undefined;
+it is unspecified how accessibility of a directory is determined.
+.SH SEE ALSO
+.BR mkstemp (3),
+.BR mktemp (3),
+.BR tmpfile (3),
+.BR tmpnam (3)
diff --git a/man/man3/termios.3 b/man/man3/termios.3
new file mode 100644
index 000000000..78731d21e
--- /dev/null
+++ b/man/man3/termios.3
@@ -0,0 +1,1235 @@
+'\" t
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de)
+.\" Fri Apr  2 11:32:09 MET DST 1993
+.\" Copyright (c) 2006-2015, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
+.\" Modified 1995-02-25 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" Modified 1995-09-02 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\" moved to man3, aeb, 950919
+.\" Modified 2001-09-22 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified 2001-12-17, aeb
+.\" Modified 2004-10-31, aeb
+.\" 2006-12-28, mtk:
+.\"     Added .SS headers to give some structure to this page; and a
+.\"     small amount of reordering.
+.\"     Added a section on canonical and noncanonical mode.
+.\"     Enhanced the discussion of "raw" mode for cfmakeraw().
+.\"     Document CMSPAR.
+.\"
+.TH termios 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+termios, tcgetattr, tcsetattr, tcsendbreak, tcdrain, tcflush, tcflow,
+cfmakeraw, cfgetospeed, cfgetispeed, cfsetispeed, cfsetospeed, cfsetspeed \-
+get and set terminal attributes, line control, get and set baud rate
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <termios.h>
+.B #include <unistd.h>
+.P
+.BI "int tcgetattr(int " fd ", struct termios *" termios_p );
+.BI "int tcsetattr(int " fd ", int " optional_actions ,
+.BI "              const struct termios *" termios_p );
+.P
+.BI "int tcsendbreak(int " fd ", int " duration );
+.BI "int tcdrain(int " fd );
+.BI "int tcflush(int " fd ", int " queue_selector );
+.BI "int tcflow(int " fd ", int " action );
+.P
+.BI "void cfmakeraw(struct termios *" termios_p );
+.P
+.BI "speed_t cfgetispeed(const struct termios *" termios_p );
+.BI "speed_t cfgetospeed(const struct termios *" termios_p );
+.P
+.BI "int cfsetispeed(struct termios *" termios_p ", speed_t " speed );
+.BI "int cfsetospeed(struct termios *" termios_p ", speed_t " speed );
+.BI "int cfsetspeed(struct termios *" termios_p ", speed_t " speed );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR cfsetspeed (),
+.BR cfmakeraw ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The termios functions describe a general terminal interface that is
+provided to control asynchronous communications ports.
+.SS The termios structure
+Many of the functions described here have a \fItermios_p\fP argument
+that is a pointer to a \fItermios\fP structure.
+This structure contains at least the following members:
+.P
+.in +4n
+.EX
+tcflag_t c_iflag;      /* input modes */
+tcflag_t c_oflag;      /* output modes */
+tcflag_t c_cflag;      /* control modes */
+tcflag_t c_lflag;      /* local modes */
+cc_t     c_cc[NCCS];   /* special characters */
+.EE
+.in
+.P
+The values that may be assigned to these fields are described below.
+In the case of the first four bit-mask fields,
+the definitions of some of the associated flags that may be set are
+exposed only if a specific feature test macro (see
+.BR feature_test_macros (7))
+is defined, as noted in brackets ("[]").
+.P
+In the descriptions below, "not in POSIX" means that the
+value is not specified in POSIX.1-2001,
+and "XSI" means that the value is specified in POSIX.1-2001
+as part of the XSI extension.
+.P
+\fIc_iflag\fP flag constants:
+.TP
+.B IGNBRK
+Ignore BREAK condition on input.
+.TP
+.B BRKINT
+If \fBIGNBRK\fP is set, a BREAK is ignored.
+If it is not set
+but \fBBRKINT\fP is set, then a BREAK causes the input and output
+queues to be flushed, and if the terminal is the controlling
+terminal of a foreground process group, it will cause a
+\fBSIGINT\fP to be sent to this foreground process group.
+When neither \fBIGNBRK\fP nor \fBBRKINT\fP are set, a BREAK
+reads as a null byte (\[aq]\e0\[aq]), except when \fBPARMRK\fP is set,
+in which case it reads as the sequence \e377 \e0 \e0.
+.TP
+.B IGNPAR
+Ignore framing errors and parity errors.
+.TP
+.B PARMRK
+If this bit is set, input bytes with parity or framing errors are
+marked when passed to the program.
+This bit is meaningful only when
+\fBINPCK\fP is set and \fBIGNPAR\fP is not set.
+The way erroneous bytes are marked is with two preceding bytes,
+\e377 and \e0.
+Thus, the program actually reads three bytes for one
+erroneous byte received from the terminal.
+If a valid byte has the value \e377,
+and \fBISTRIP\fP (see below) is not set,
+the program might confuse it with the prefix that marks a
+parity error.
+Therefore, a valid byte \e377 is passed to the program as two
+bytes, \e377 \e377, in this case.
+.IP
+If neither \fBIGNPAR\fP nor \fBPARMRK\fP
+is set, read a character with a parity error or framing error
+as \e0.
+.TP
+.B INPCK
+Enable input parity checking.
+.TP
+.B ISTRIP
+Strip off eighth bit.
+.TP
+.B INLCR
+Translate NL to CR on input.
+.TP
+.B IGNCR
+Ignore carriage return on input.
+.TP
+.B ICRNL
+Translate carriage return to newline on input (unless \fBIGNCR\fP is set).
+.TP
+.B IUCLC
+(not in POSIX) Map uppercase characters to lowercase on input.
+.TP
+.B IXON
+Enable XON/XOFF flow control on output.
+.TP
+.B IXANY
+(XSI) Typing any character will restart stopped output.
+(The default is to allow just the START character to restart output.)
+.TP
+.B IXOFF
+Enable XON/XOFF flow control on input.
+.TP
+.B IMAXBEL
+(not in POSIX) Ring bell when input queue is full.
+Linux does not implement this bit, and acts as if it is always set.
+.TP
+.BR IUTF8 " (since Linux 2.6.4)"
+(not in POSIX) Input is UTF8;
+this allows character-erase to be correctly performed in cooked mode.
+.P
+.I c_oflag
+flag constants:
+.TP
+.B OPOST
+Enable implementation-defined output processing.
+.TP
+.B OLCUC
+(not in POSIX) Map lowercase characters to uppercase on output.
+.TP
+.B ONLCR
+(XSI) Map NL to CR-NL on output.
+.TP
+.B OCRNL
+Map CR to NL on output.
+.TP
+.B ONOCR
+Don't output CR at column 0.
+.TP
+.B ONLRET
+The NL character is assumed to do the carriage-return function;
+the kernel's idea of the current column is set to 0
+after both NL and CR.
+.TP
+.B OFILL
+Send fill characters for a delay, rather than using a timed delay.
+.TP
+.B OFDEL
+Fill character is ASCII DEL (0177).
+If unset, fill character is ASCII NUL (\[aq]\e0\[aq]).
+(Not implemented on Linux.)
+.TP
+.B NLDLY
+Newline delay mask.
+Values are \fBNL0\fP and \fBNL1\fP.
+[requires
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+or
+.BR _XOPEN_SOURCE ]
+.TP
+.B CRDLY
+Carriage return delay mask.
+Values are \fBCR0\fP, \fBCR1\fP, \fBCR2\fP, or \fBCR3\fP.
+[requires
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+or
+.BR _XOPEN_SOURCE ]
+.TP
+.B TABDLY
+Horizontal tab delay mask.
+Values are \fBTAB0\fP, \fBTAB1\fP, \fBTAB2\fP, \fBTAB3\fP (or \fBXTABS\fP,
+but see the
+.B BUGS
+section).
+A value of TAB3, that is, XTABS, expands tabs to spaces
+(with tab stops every eight columns).
+[requires
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+or
+.BR _XOPEN_SOURCE ]
+.TP
+.B BSDLY
+Backspace delay mask.
+Values are \fBBS0\fP or \fBBS1\fP.
+(Has never been implemented.)
+[requires
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+or
+.BR _XOPEN_SOURCE ]
+.TP
+.B VTDLY
+Vertical tab delay mask.
+Values are \fBVT0\fP or \fBVT1\fP.
+.TP
+.B FFDLY
+Form feed delay mask.
+Values are \fBFF0\fP or \fBFF1\fP.
+[requires
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+or
+.BR _XOPEN_SOURCE ]
+.P
+\fIc_cflag\fP flag constants:
+.TP
+.B CBAUD
+(not in POSIX) Baud speed mask (4+1 bits).
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.TP
+.B CBAUDEX
+(not in POSIX) Extra baud speed mask (1 bit), included in
+.BR CBAUD .
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.IP
+(POSIX says that the baud speed is stored in the
+.I termios
+structure without specifying where precisely, and provides
+.BR cfgetispeed ()
+and
+.BR cfsetispeed ()
+for getting at it.
+Some systems use bits selected by
+.B CBAUD
+in
+.IR c_cflag ,
+other systems use separate fields, for example,
+.I sg_ispeed
+and
+.IR sg_ospeed .)
+.TP
+.B CSIZE
+Character size mask.
+Values are \fBCS5\fP, \fBCS6\fP, \fBCS7\fP, or \fBCS8\fP.
+.TP
+.B CSTOPB
+Set two stop bits, rather than one.
+.TP
+.B CREAD
+Enable receiver.
+.TP
+.B PARENB
+Enable parity generation on output and parity checking for input.
+.TP
+.B PARODD
+If set, then parity for input and output is odd;
+otherwise even parity is used.
+.TP
+.B HUPCL
+Lower modem control lines after last process closes the device (hang up).
+.TP
+.B CLOCAL
+Ignore modem control lines.
+.TP
+.B LOBLK
+(not in POSIX) Block output from a noncurrent shell layer.
+For use by \fBshl\fP (shell layers).
+(Not implemented on Linux.)
+.TP
+.B CIBAUD
+(not in POSIX) Mask for input speeds.
+The values for the
+.B CIBAUD
+bits are
+the same as the values for the
+.B CBAUD
+bits, shifted left
+.B IBSHIFT
+bits.
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+(Not implemented in glibc, supported on Linux via
+.BR TCGET *
+and
+.BR TCSET *
+ioctls; see
+.BR ioctl_tty (2))
+.TP
+.B CMSPAR
+(not in POSIX)
+Use "stick" (mark/space) parity (supported on certain serial
+devices): if
+.B PARODD
+is set, the parity bit is always 1; if
+.B PARODD
+is not set, then the parity bit is always 0.
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.TP
+.B CRTSCTS
+(not in POSIX) Enable RTS/CTS (hardware) flow control.
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.P
+\fIc_lflag\fP flag constants:
+.TP
+.B ISIG
+When any of the characters INTR, QUIT, SUSP, or DSUSP are received,
+generate the corresponding signal.
+.TP
+.B ICANON
+Enable canonical mode (described below).
+.TP
+.B XCASE
+(not in POSIX; not supported under Linux)
+If \fBICANON\fP is also set, terminal is uppercase only.
+Input is converted to lowercase, except for characters preceded by \e.
+On output, uppercase characters are preceded by \e and lowercase
+characters are converted to uppercase.
+[requires
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+or
+.BR _XOPEN_SOURCE ]
+.\" glibc is probably now wrong to allow
+.\" Define
+.\" .B _XOPEN_SOURCE
+.\" to expose
+.\" .BR XCASE .
+.TP
+.B ECHO
+Echo input characters.
+.TP
+.B ECHOE
+If \fBICANON\fP is also set, the ERASE character erases the preceding
+input character, and WERASE erases the preceding word.
+.TP
+.B ECHOK
+If \fBICANON\fP is also set, the KILL character erases the current line.
+.TP
+.B ECHONL
+If \fBICANON\fP is also set, echo the NL character even if ECHO is not set.
+.TP
+.B ECHOCTL
+(not in POSIX) If \fBECHO\fP is also set,
+terminal special characters other than
+TAB, NL, START, and STOP are echoed as \fB\[ha]X\fP,
+where X is the character with
+ASCII code 0x40 greater than the special character.
+For example, character
+0x08 (BS) is echoed as \fB\[ha]H\fP.
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.TP
+.B ECHOPRT
+(not in POSIX) If \fBICANON\fP and \fBECHO\fP are also set, characters
+are printed as they are being erased.
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.TP
+.B ECHOKE
+(not in POSIX) If \fBICANON\fP is also set, KILL is echoed by erasing
+each character on the line, as specified by \fBECHOE\fP and \fBECHOPRT\fP.
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.TP
+.B DEFECHO
+(not in POSIX) Echo only when a process is reading.
+(Not implemented on Linux.)
+.TP
+.B FLUSHO
+(not in POSIX; not supported under Linux)
+Output is being flushed.
+This flag is toggled by typing
+the DISCARD character.
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.TP
+.B NOFLSH
+Disable flushing the input and output queues when generating signals for the
+INT, QUIT, and SUSP characters.
+.\" Stevens lets SUSP only flush the input queue
+.TP
+.B TOSTOP
+Send the
+.B SIGTTOU
+signal to the process group of a background process
+which tries to write to its controlling terminal.
+.TP
+.B PENDIN
+(not in POSIX; not supported under Linux)
+All characters in the input queue are reprinted when
+the next character is read.
+.RB ( bash (1)
+handles typeahead this way.)
+[requires
+.B _BSD_SOURCE
+or
+.BR _SVID_SOURCE ]
+.TP
+.B IEXTEN
+Enable implementation-defined input processing.
+This flag, as well as \fBICANON\fP must be enabled for the
+special characters EOL2, LNEXT, REPRINT, WERASE to be interpreted,
+and for the \fBIUCLC\fP flag to be effective.
+.P
+The \fIc_cc\fP array defines the terminal special characters.
+The symbolic indices (initial values) and meaning are:
+.TP
+.B VDISCARD
+(not in POSIX; not supported under Linux; 017, SI, Ctrl-O)
+Toggle: start/stop discarding pending output.
+Recognized when
+.B IEXTEN
+is set, and then not passed as input.
+.TP
+.B VDSUSP
+(not in POSIX; not supported under Linux; 031, EM, Ctrl-Y)
+Delayed suspend character (DSUSP):
+send
+.B SIGTSTP
+signal when the character is read by the user program.
+Recognized when
+.B IEXTEN
+and
+.B ISIG
+are set, and the system supports
+job control, and then not passed as input.
+.TP
+.B VEOF
+(004, EOT, Ctrl-D)
+End-of-file character (EOF).
+More precisely: this character causes the pending tty buffer to be sent
+to the waiting user program without waiting for end-of-line.
+If it is the first character of the line, the
+.BR read (2)
+in the user program returns 0, which signifies end-of-file.
+Recognized when
+.B ICANON
+is set, and then not passed as input.
+.TP
+.B VEOL
+(0, NUL)
+Additional end-of-line character (EOL).
+Recognized when
+.B ICANON
+is set.
+.TP
+.B VEOL2
+(not in POSIX; 0, NUL)
+Yet another end-of-line character (EOL2).
+Recognized when
+.B ICANON
+is set.
+.TP
+.B VERASE
+(0177, DEL, rubout, or 010, BS, Ctrl-H, or also #)
+Erase character (ERASE).
+This erases the previous not-yet-erased character,
+but does not erase past EOF or beginning-of-line.
+Recognized when
+.B ICANON
+is set, and then not passed as input.
+.TP
+.B VINTR
+(003, ETX, Ctrl-C, or also 0177, DEL, rubout)
+Interrupt character (INTR).
+Send a
+.B SIGINT
+signal.
+Recognized when
+.B ISIG
+is set, and then not passed as input.
+.TP
+.B VKILL
+(025, NAK, Ctrl-U, or Ctrl-X, or also @)
+Kill character (KILL).
+This erases the input since the last EOF or beginning-of-line.
+Recognized when
+.B ICANON
+is set, and then not passed as input.
+.TP
+.B VLNEXT
+(not in POSIX; 026, SYN, Ctrl-V)
+Literal next (LNEXT).
+Quotes the next input character, depriving it of
+a possible special meaning.
+Recognized when
+.B IEXTEN
+is set, and then not passed as input.
+.TP
+.B VMIN
+Minimum number of characters for noncanonical read (MIN).
+.TP
+.B VQUIT
+(034, FS, Ctrl-\e)
+Quit character (QUIT).
+Send
+.B SIGQUIT
+signal.
+Recognized when
+.B ISIG
+is set, and then not passed as input.
+.TP
+.B VREPRINT
+(not in POSIX; 022, DC2, Ctrl-R)
+Reprint unread characters (REPRINT).
+Recognized when
+.B ICANON
+and
+.B IEXTEN
+are set, and then not passed as input.
+.TP
+.B VSTART
+(021, DC1, Ctrl-Q)
+Start character (START).
+Restarts output stopped by the Stop character.
+Recognized when
+.B IXON
+is set, and then not passed as input.
+.TP
+.B VSTATUS
+(not in POSIX; not supported under Linux;
+status request: 024, DC4, Ctrl-T).
+Status character (STATUS).
+Display status information at terminal,
+including state of foreground process and amount of CPU time it has consumed.
+Also sends a
+.B SIGINFO
+signal (not supported on Linux) to the foreground process group.
+.TP
+.B VSTOP
+(023, DC3, Ctrl-S)
+Stop character (STOP).
+Stop output until Start character typed.
+Recognized when
+.B IXON
+is set, and then not passed as input.
+.TP
+.B VSUSP
+(032, SUB, Ctrl-Z)
+Suspend character (SUSP).
+Send
+.B SIGTSTP
+signal.
+Recognized when
+.B ISIG
+is set, and then not passed as input.
+.TP
+.B VSWTCH
+(not in POSIX; not supported under Linux; 0, NUL)
+Switch character (SWTCH).
+Used in System V to switch shells in
+.IR "shell layers" ,
+a predecessor to shell job control.
+.TP
+.B VTIME
+Timeout in deciseconds for noncanonical read (TIME).
+.TP
+.B VWERASE
+(not in POSIX; 027, ETB, Ctrl-W)
+Word erase (WERASE).
+Recognized when
+.B ICANON
+and
+.B IEXTEN
+are set, and then not passed as input.
+.P
+An individual terminal special character can be disabled by setting
+the value of the corresponding
+.I c_cc
+element to
+.BR _POSIX_VDISABLE .
+.P
+The above symbolic subscript values are all different, except that
+.BR VTIME ,
+.B VMIN
+may have the same value as
+.BR VEOL ,
+.BR VEOF ,
+respectively.
+In noncanonical mode the special character meaning is replaced
+by the timeout meaning.
+For an explanation of
+.B VMIN
+and
+.BR VTIME ,
+see the description of
+noncanonical mode below.
+.SS Retrieving and changing terminal settings
+.BR tcgetattr ()
+gets the parameters associated with the object referred by \fIfd\fP and
+stores them in the \fItermios\fP structure referenced by
+\fItermios_p\fP.
+This function may be invoked from a background process;
+however, the terminal attributes may be subsequently changed by a
+foreground process.
+.P
+.BR tcsetattr ()
+sets the parameters associated with the terminal (unless support is
+required from the underlying hardware that is not available) from the
+\fItermios\fP structure referred to by \fItermios_p\fP.
+\fIoptional_actions\fP specifies when the changes take effect:
+.TP
+.B TCSANOW
+the change occurs immediately.
+.TP
+.B TCSADRAIN
+the change occurs after all output written to
+.I fd
+has been transmitted.
+This option should be used when changing
+parameters that affect output.
+.TP
+.B TCSAFLUSH
+the change occurs after all output written to the object referred by
+.I fd
+has been transmitted, and all input that has been received but not read
+will be discarded before the change is made.
+.SS Canonical and noncanonical mode
+The setting of the
+.B ICANON
+canon flag in
+.I c_lflag
+determines whether the terminal is operating in canonical mode
+.RB ( ICANON
+set) or
+noncanonical mode
+.RB ( ICANON
+unset).
+By default,
+.B ICANON
+is set.
+.P
+In canonical mode:
+.IP \[bu] 3
+Input is made available line by line.
+An input line is available when one of the line delimiters
+is typed (NL, EOL, EOL2; or EOF at the start of line).
+Except in the case of EOF, the line delimiter is included
+in the buffer returned by
+.BR read (2).
+.IP \[bu]
+Line editing is enabled (ERASE, KILL;
+and if the
+.B IEXTEN
+flag is set: WERASE, REPRINT, LNEXT).
+A
+.BR read (2)
+returns at most one line of input; if the
+.BR read (2)
+requested fewer bytes than are available in the current line of input,
+then only as many bytes as requested are read,
+and the remaining characters will be available for a future
+.BR read (2).
+.IP \[bu]
+The maximum line length is 4096 chars
+(including the terminating newline character);
+lines longer than 4096 chars are truncated.
+After 4095 characters, input processing (e.g.,
+.B ISIG
+and
+.B ECHO*
+processing) continues, but any input data after 4095 characters up to
+(but not including) any terminating newline is discarded.
+This ensures that the terminal can always receive
+more input until at least one line can be read.
+.P
+In noncanonical mode input is available immediately (without
+the user having to type a line-delimiter character),
+no input processing is performed,
+and line editing is disabled.
+The read buffer will only accept 4095 chars; this provides the
+necessary space for a newline char if the input mode is switched
+to canonical.
+The settings of MIN
+.RI ( c_cc[VMIN] )
+and TIME
+.RI ( c_cc[VTIME] )
+determine the circumstances in which a
+.BR read (2)
+completes; there are four distinct cases:
+.TP
+MIN == 0, TIME == 0 (polling read)
+If data is available,
+.BR read (2)
+returns immediately, with the lesser of the number of bytes
+available, or the number of bytes requested.
+If no data is available,
+.BR read (2)
+returns 0.
+.TP
+MIN > 0, TIME == 0 (blocking read)
+.BR read (2)
+blocks until MIN bytes are available,
+and returns up to the number of bytes requested.
+.TP
+MIN == 0, TIME > 0 (read with timeout)
+TIME specifies the limit for a timer in tenths of a second.
+The timer is started when
+.BR read (2)
+is called.
+.BR read (2)
+returns either when at least one byte of data is available,
+or when the timer expires.
+If the timer expires without any input becoming available,
+.BR read (2)
+returns 0.
+If data is already available at the time of the call to
+.BR read (2),
+the call behaves as though the data was received immediately after the call.
+.TP
+MIN > 0, TIME > 0 (read with interbyte timeout)
+TIME specifies the limit for a timer in tenths of a second.
+Once an initial byte of input becomes available,
+the timer is restarted after each further byte is received.
+.BR read (2)
+returns when any of the following conditions is met:
+.RS
+.IP \[bu] 3
+MIN bytes have been received.
+.IP \[bu]
+The interbyte timer expires.
+.IP \[bu]
+The number of bytes requested by
+.BR read (2)
+has been received.
+(POSIX does not specify this termination condition,
+and on some other implementations
+.\" e.g., Solaris
+.BR read (2)
+does not return in this case.)
+.RE
+.IP
+Because the timer is started only after the initial byte
+becomes available, at least one byte will be read.
+If data is already available at the time of the call to
+.BR read (2),
+the call behaves as though the data was received immediately after the call.
+.P
+POSIX
+.\" POSIX.1-2008 XBD 11.1.7
+does not specify whether the setting of the
+.B O_NONBLOCK
+file status flag takes precedence over the MIN and TIME settings.
+If
+.B O_NONBLOCK
+is set, a
+.BR read (2)
+in noncanonical mode may return immediately,
+regardless of the setting of MIN or TIME.
+Furthermore, if no data is available,
+POSIX permits a
+.BR read (2)
+in noncanonical mode to return either 0, or \-1 with
+.I errno
+set to
+.BR EAGAIN .
+.SS Raw mode
+.BR cfmakeraw ()
+sets the terminal to something like the
+"raw" mode of the old Version 7 terminal driver:
+input is available character by character,
+echoing is disabled, and all special processing of
+terminal input and output characters is disabled.
+The terminal attributes are set as follows:
+.P
+.in +4n
+.EX
+termios_p\->c_iflag &= \[ti](IGNBRK | BRKINT | PARMRK | ISTRIP
+                | INLCR | IGNCR | ICRNL | IXON);
+termios_p\->c_oflag &= \[ti]OPOST;
+termios_p\->c_lflag &= \[ti](ECHO | ECHONL | ICANON | ISIG | IEXTEN);
+termios_p\->c_cflag &= \[ti](CSIZE | PARENB);
+termios_p\->c_cflag |= CS8;
+.EE
+.in
+.\"
+.SS Line control
+.BR tcsendbreak ()
+transmits a continuous stream of zero-valued bits for a specific
+duration, if the terminal is using asynchronous serial data
+transmission.
+If \fIduration\fP is zero, it transmits zero-valued bits
+for at least 0.25 seconds, and not more than 0.5 seconds.
+If \fIduration\fP is not zero, it sends zero-valued bits for some
+implementation-defined length of time.
+.P
+If the terminal is not using asynchronous serial data transmission,
+.BR tcsendbreak ()
+returns without taking any action.
+.P
+.BR tcdrain ()
+waits until all output written to the object referred to by
+.I fd
+has been transmitted.
+.P
+.BR tcflush ()
+discards data written to the object referred to by
+.I fd
+but not transmitted, or data received but not read, depending on the
+value of
+.IR queue_selector :
+.TP
+.B TCIFLUSH
+flushes data received but not read.
+.TP
+.B TCOFLUSH
+flushes data written but not transmitted.
+.TP
+.B TCIOFLUSH
+flushes both data received but not read, and data written but not
+transmitted.
+.P
+.BR tcflow ()
+suspends transmission or reception of data on the object referred to by
+.IR fd ,
+depending on the value of
+.IR action :
+.TP
+.B TCOOFF
+suspends output.
+.TP
+.B TCOON
+restarts suspended output.
+.TP
+.B TCIOFF
+transmits a STOP character, which stops the terminal device from
+transmitting data to the system.
+.TP
+.B TCION
+transmits a START character, which starts the terminal device
+transmitting data to the system.
+.P
+The default on open of a terminal file is that neither its input nor its
+output is suspended.
+.SS Line speed
+The baud rate functions are provided for getting and setting the values
+of the input and output baud rates in the \fItermios\fP structure.
+The new values do not take effect
+until
+.BR tcsetattr ()
+is successfully called.
+.P
+Setting the speed to \fBB0\fP instructs the modem to "hang up".
+The actual bit rate corresponding to \fBB38400\fP may be altered with
+.BR setserial (8).
+.P
+The input and output baud rates are stored in the \fItermios\fP
+structure.
+.P
+.BR cfgetospeed ()
+returns the output baud rate stored in the \fItermios\fP structure
+pointed to by
+.IR termios_p .
+.P
+.BR cfsetospeed ()
+sets the output baud rate stored in the \fItermios\fP structure pointed
+to by \fItermios_p\fP to \fIspeed\fP, which must be one of these constants:
+.RS
+.TP
+.B B0
+.TQ
+.B B50
+.TQ
+.B B75
+.TQ
+.B B110
+.TQ
+.B B134
+.TQ
+.B B150
+.TQ
+.B B200
+.TQ
+.B B300
+.TQ
+.B B600
+.TQ
+.B B1200
+.TQ
+.B B1800
+.TQ
+.B B2400
+.TQ
+.B B4800
+.TQ
+.B B9600
+.TQ
+.B B19200
+.TQ
+.B B38400
+.TQ
+.B B57600
+.TQ
+.B B115200
+.TQ
+.B B230400
+.TQ
+.B B460800
+.TQ
+.B B500000
+.TQ
+.B B576000
+.TQ
+.B B921600
+.TQ
+.B B1000000
+.TQ
+.B B1152000
+.TQ
+.B B1500000
+.TQ
+.B B2000000
+.RE
+.P
+These constants are additionally supported on the SPARC architecture:
+.RS
+.TP
+.B B76800
+.TQ
+.B B153600
+.TQ
+.B B307200
+.TQ
+.B B614400
+.RE
+.P
+These constants are additionally supported on non-SPARC architectures:
+.RS
+.TP
+.B B2500000
+.TQ
+.B B3000000
+.TQ
+.B B3500000
+.TQ
+.B B4000000
+.RE
+.P
+Due to differences between architectures, portable applications should check
+if a particular
+.BI B nnn
+constant is defined prior to using it.
+.P
+The zero baud rate,
+.BR B0 ,
+is used to terminate the connection.
+If
+.B B0
+is specified, the modem control lines shall no longer be asserted.
+Normally, this will disconnect the line.
+.B CBAUDEX
+is a mask
+for the speeds beyond those defined in POSIX.1 (57600 and above).
+Thus,
+.BR B57600 " & " CBAUDEX
+is nonzero.
+.P
+Setting the baud rate to a value other than those defined by
+.BI B nnn
+constants is possible via the
+.B TCSETS2
+ioctl; see
+.BR ioctl_tty (2).
+.P
+.BR cfgetispeed ()
+returns the input baud rate stored in the
+.I termios
+structure.
+.P
+.BR cfsetispeed ()
+sets the input baud rate stored in the
+.I termios
+structure to
+.IR speed ,
+which must be specified as one of the
+.BI B nnn
+constants listed above for
+.BR cfsetospeed ().
+If the input baud rate is set to the literal constant
+.B 0
+(not the symbolic constant
+.BR B0 ),
+the input baud rate will be
+equal to the output baud rate.
+.P
+.BR cfsetspeed ()
+is a 4.4BSD extension.
+It takes the same arguments as
+.BR cfsetispeed (),
+and sets both input and output speed.
+.SH RETURN VALUE
+.BR cfgetispeed ()
+returns the input baud rate stored in the
+\fItermios\fP
+structure.
+.P
+.BR cfgetospeed ()
+returns the output baud rate stored in the \fItermios\fP structure.
+.P
+All other functions return:
+.TP
+.B 0
+on success.
+.TP
+.B \-1
+on failure and set
+.I errno
+to indicate the error.
+.P
+Note that
+.BR tcsetattr ()
+returns success if \fIany\fP of the requested changes could be
+successfully carried out.
+Therefore, when making multiple changes
+it may be necessary to follow this call with a further call to
+.BR tcgetattr ()
+to check that all changes have been performed successfully.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tcgetattr (),
+.BR tcsetattr (),
+.BR tcdrain (),
+.BR tcflush (),
+.BR tcflow (),
+.BR tcsendbreak (),
+.BR cfmakeraw (),
+.BR cfgetispeed (),
+.BR cfgetospeed (),
+.BR cfsetispeed (),
+.BR cfsetospeed (),
+.BR cfsetspeed ()
+T}	Thread safety	MT-Safe
+.TE
+.\" FIXME: The markings are different from that in the glibc manual.
+.\" markings in glibc manual are more detailed:
+.\"
+.\"     tcsendbreak: MT-Unsafe race:tcattr(filedes)/bsd
+.\"     tcflow: MT-Unsafe race:tcattr(filedes)/bsd
+.\"
+.\" glibc manual says /bsd indicate the preceding marker only applies
+.\" when the underlying kernel is a BSD kernel.
+.\" So, it is safety in Linux kernel.
+.SH STANDARDS
+.TP
+.BR tcgetattr ()
+.TQ
+.BR tcsetattr ()
+.TQ
+.BR tcsendbreak ()
+.TQ
+.BR tcdrain ()
+.TQ
+.BR tcflush ()
+.TQ
+.BR tcflow ()
+.TQ
+.BR cfgetispeed ()
+.TQ
+.BR cfgetospeed ()
+.TQ
+.BR cfsetispeed ()
+.TQ
+.BR cfsetospeed ()
+POSIX.1-2008.
+.TP
+.BR cfmakeraw ()
+.TQ
+.BR cfsetspeed ()
+BSD.
+.SH HISTORY
+.TP
+.BR tcgetattr ()
+.TQ
+.BR tcsetattr ()
+.TQ
+.BR tcsendbreak ()
+.TQ
+.BR tcdrain ()
+.TQ
+.BR tcflush ()
+.TQ
+.BR tcflow ()
+.TQ
+.BR cfgetispeed ()
+.TQ
+.BR cfgetospeed ()
+.TQ
+.BR cfsetispeed ()
+.TQ
+.BR cfsetospeed ()
+POSIX.1-2001.
+.TP
+.BR cfmakeraw ()
+.TQ
+.BR cfsetspeed ()
+BSD.
+.SH NOTES
+UNIX\ V7 and several later systems have a list of baud rates
+where after the values
+.B B0
+through
+.B B9600
+one finds the two constants
+.BR EXTA ,
+.B EXTB
+("External A" and "External B").
+Many systems extend the list with much higher baud rates.
+.P
+The effect of a nonzero \fIduration\fP with
+.BR tcsendbreak ()
+varies.
+SunOS specifies a break of
+.I "duration\ *\ N"
+seconds, where \fIN\fP is at least 0.25, and not more than 0.5.
+Linux, AIX, DU, Tru64 send a break of
+.I duration
+milliseconds.
+FreeBSD and NetBSD and HP-UX and MacOS ignore the value of
+.IR duration .
+Under Solaris and UnixWare,
+.BR tcsendbreak ()
+with nonzero
+.I duration
+behaves like
+.BR tcdrain ().
+.\" libc4 until 4.7.5, glibc for sysv: EINVAL for duration > 0.
+.\" libc4.7.6, libc5, glibc for unix: duration in ms.
+.\" glibc for bsd: duration in us
+.\" glibc for sunos4: ignore duration
+.SH BUGS
+.\" kernel 77e5bff1640432f28794a00800955e646dcd7455
+.\" glibc 573963e32ffac46d9891970ddebde2ac3212c5c0
+On the Alpha architecture before Linux 4.16 (and glibc before glibc 2.28), the
+.B XTABS
+value was different from
+.B TAB3
+and it was ignored by the
+.B N_TTY
+line discipline code of the terminal driver as a result
+(because as it wasn't part of the
+.B TABDLY
+mask).
+.SH SEE ALSO
+.BR reset (1),
+.BR setterm (1),
+.BR stty (1),
+.BR tput (1),
+.BR tset (1),
+.BR tty (1),
+.BR ioctl_console (2),
+.BR ioctl_tty (2),
+.BR cc_t (3type),
+.BR speed_t (3type),
+.BR tcflag_t (3type),
+.BR setserial (8)
diff --git a/man/man3/tfind.3 b/man/man3/tfind.3
new file mode 100644
index 000000000..72f125195
--- /dev/null
+++ b/man/man3/tfind.3
@@ -0,0 +1 @@
+.so man3/tsearch.3
diff --git a/man/man3/tgamma.3 b/man/man3/tgamma.3
new file mode 100644
index 000000000..e55e95c35
--- /dev/null
+++ b/man/man3/tgamma.3
@@ -0,0 +1,216 @@
+'\" t
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Based on glibc infopages
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\" Modified 2004-11-15, fixed error noted by Fabian Kreutz
+.\"	 <kreutz@dbs.uni-hannover.de>
+.\"
+.TH tgamma 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tgamma, tgammaf, tgammal \- true gamma function
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double tgamma(double " x );
+.BI "float tgammaf(float " x );
+.BI "long double tgammal(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR tgamma (),
+.BR tgammaf (),
+.BR tgammal ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions calculate the Gamma function of
+.IR x .
+.P
+The Gamma function is defined by
+.P
+.RS
+Gamma(x) = integral from 0 to infinity of t\[ha](x\-1) e\[ha]\-t dt
+.RE
+.P
+It is defined for every real number except for nonpositive integers.
+For nonnegative integral
+.I m
+one has
+.P
+.RS
+Gamma(m+1) = m!
+.RE
+.P
+and, more generally, for all
+.IR x :
+.P
+.RS
+Gamma(x+1) = x * Gamma(x)
+.RE
+.P
+Furthermore, the following is valid for all values of
+.I x
+outside the poles:
+.P
+.RS
+Gamma(x) * Gamma(1 \- x) = PI / sin(PI * x)
+.RE
+.SH RETURN VALUE
+On success, these functions return Gamma(x).
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is positive infinity, positive infinity is returned.
+.P
+If
+.I x
+is a negative integer, or is negative infinity,
+a domain error occurs,
+and a NaN is returned.
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the correct mathematical sign.
+.P
+If the result underflows,
+a range error occurs,
+and the functions return 0, with the correct mathematical sign.
+.P
+If
+.I x
+is \-0 or +0,
+a pole error occurs,
+and the functions return
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+respectively, with the same sign as the 0.
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is a negative integer, or negative infinity
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised (but see BUGS).
+.TP
+Pole error: \fIx\fP is +0 or \-0
+.I errno
+is set to
+.BR ERANGE .
+A divide-by-zero floating-point exception
+.RB ( FE_DIVBYZERO )
+is raised.
+.TP
+Range error: result overflow
+.I errno
+is set to
+.BR ERANGE .
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.P
+glibc also gives the following error which is not specified
+in C99 or POSIX.1-2001.
+.TP
+Range error: result underflow
+.\" e.g., tgamma(-172.5) on glibc 2.8/x86-32
+.\" .I errno
+.\" is set to
+.\" .BR ERANGE .
+An underflow floating-point exception
+.RB ( FE_UNDERFLOW )
+is raised, and
+.I errno
+is set to
+.BR ERANGE .
+.\" glibc (as at 2.8) also supports an inexact
+.\" exception for various cases.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tgamma (),
+.BR tgammaf (),
+.BR tgammal ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH NOTES
+This function had to be called "true gamma function"
+since there is already a function
+.BR gamma (3)
+that returns something else (see
+.BR gamma (3)
+for details).
+.SH BUGS
+Before glibc 2.18, the glibc implementation of these functions did not set
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6809
+.I errno
+to
+.B EDOM
+when
+.I x
+is negative infinity.
+.P
+Before glibc 2.19,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6810
+the glibc implementation of these functions did not set
+.I errno
+to
+.B ERANGE
+on an underflow range error.
+.P
+.\"
+In glibc versions 2.3.3 and earlier,
+an argument of +0 or \-0 incorrectly produced a domain error
+.RI ( errno
+set to
+.B EDOM
+and an
+.B FE_INVALID
+exception raised), rather than a pole error.
+.SH SEE ALSO
+.BR gamma (3),
+.BR lgamma (3)
diff --git a/man/man3/tgammaf.3 b/man/man3/tgammaf.3
new file mode 100644
index 000000000..4a0248a0d
--- /dev/null
+++ b/man/man3/tgammaf.3
@@ -0,0 +1 @@
+.so man3/tgamma.3
diff --git a/man/man3/tgammal.3 b/man/man3/tgammal.3
new file mode 100644
index 000000000..4a0248a0d
--- /dev/null
+++ b/man/man3/tgammal.3
@@ -0,0 +1 @@
+.so man3/tgamma.3
diff --git a/man/man3/timegm.3 b/man/man3/timegm.3
new file mode 100644
index 000000000..49f5a73ff
--- /dev/null
+++ b/man/man3/timegm.3
@@ -0,0 +1,92 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH timegm 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+timegm, timelocal \- inverses of gmtime and localtime
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BI "[[deprecated]] time_t timelocal(struct tm *" tm );
+.BI "time_t timegm(struct tm *" tm );
+.P
+.fi
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR timelocal (),
+.BR timegm ():
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The functions
+.BR timelocal ()
+and
+.BR timegm ()
+are the inverses of
+.BR localtime (3)
+and
+.BR gmtime (3).
+Both functions take a broken-down time and convert it to calendar time
+(seconds since the Epoch, 1970-01-01 00:00:00 +0000, UTC).
+The difference between the two functions is that
+.BR timelocal ()
+takes the local timezone into account when doing the conversion, while
+.BR timegm ()
+takes the input value to be Coordinated Universal Time (UTC).
+.SH RETURN VALUE
+On success,
+these functions return the calendar time (seconds since the Epoch),
+expressed as a value of type
+.IR time_t .
+On error, they return the value
+.I (time_t)\ \-1
+and set
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EOVERFLOW
+The result cannot be represented.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR timelocal (),
+.BR timegm ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+BSD.
+.SH HISTORY
+GNU, BSD.
+.P
+The
+.BR timelocal ()
+function is equivalent to the POSIX standard function
+.BR mktime (3).
+There is no reason to ever use it.
+.SH SEE ALSO
+.BR gmtime (3),
+.BR localtime (3),
+.BR mktime (3),
+.BR tzset (3)
diff --git a/man/man3/timelocal.3 b/man/man3/timelocal.3
new file mode 100644
index 000000000..45d4c0907
--- /dev/null
+++ b/man/man3/timelocal.3
@@ -0,0 +1 @@
+.so man3/timegm.3
diff --git a/man/man3/timeradd.3 b/man/man3/timeradd.3
new file mode 100644
index 000000000..2a34dbacd
--- /dev/null
+++ b/man/man3/timeradd.3
@@ -0,0 +1,143 @@
+.\" Copyright (c) 2007 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2007-07-31, mtk, Created
+.\"
+.TH timeradd 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+timeradd, timersub, timercmp, timerclear, timerisset \- timeval operations
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/time.h>
+.P
+.BI "void timeradd(struct timeval *" a ", struct timeval *" b ,
+.BI "              struct timeval *" res );
+.BI "void timersub(struct timeval *" a ", struct timeval *" b ,
+.BI "              struct timeval *" res );
+.P
+.BI "void timerclear(struct timeval *" tvp );
+.BI "int timerisset(struct timeval *" tvp );
+.P
+.BI "int timercmp(struct timeval *" a ", struct timeval *" b ", " CMP );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    glibc 2.19 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The macros are provided to operate on
+.I timeval
+structures, defined in
+.I <sys/time.h>
+as:
+.P
+.in +4n
+.EX
+struct timeval {
+    time_t      tv_sec;     /* seconds */
+    suseconds_t tv_usec;    /* microseconds */
+};
+.EE
+.in
+.P
+.BR timeradd ()
+adds the time values in
+.I a
+and
+.IR b ,
+and places the sum in the
+.I timeval
+pointed to by
+.IR res .
+The result is normalized such that
+.I res\->tv_usec
+has a value in the range 0 to 999,999.
+.P
+.BR timersub ()
+subtracts the time value in
+.I b
+from the time value in
+.IR a ,
+and places the result in the
+.I timeval
+pointed to by
+.IR res .
+The result is normalized such that
+.I res\->tv_usec
+has a value in the range 0 to 999,999.
+.P
+.BR timerclear ()
+zeros out the
+.I timeval
+structure pointed to by
+.IR tvp ,
+so that it represents the Epoch: 1970-01-01 00:00:00 +0000 (UTC).
+.P
+.BR timerisset ()
+returns true (nonzero) if either field of the
+.I timeval
+structure pointed to by
+.I tvp
+contains a nonzero value.
+.P
+.BR timercmp ()
+compares the timer values in
+.I a
+and
+.I b
+using the comparison operator
+.IR CMP ,
+and returns true (nonzero) or false (0) depending on
+the result of the comparison.
+Some systems (but not Linux/glibc),
+have a broken
+.BR timercmp ()
+implementation,
+.\" HP-UX, Tru64, Irix have a definition like:
+.\"#define timercmp(tvp, uvp, cmp) \
+.\"    ((tvp)->tv_sec cmp (uvp)->tv_sec || \
+.\"    (tvp)->tv_sec == (uvp)->tv_sec && (tvp)->tv_usec cmp (uvp)->tv_usec)
+in which
+.I CMP
+of
+.IR >= ,
+.IR <= ,
+and
+.I ==
+do not work;
+portable applications can instead use
+.P
+.in +4n
+.EX
+!timercmp(..., <)
+!timercmp(..., >)
+!timercmp(..., !=)
+.EE
+.in
+.SH RETURN VALUE
+.BR timerisset ()
+and
+.BR timercmp ()
+return true (nonzero) or false (0).
+.SH ERRORS
+No errors are defined.
+.SH STANDARDS
+None.
+.SH HISTORY
+BSD.
+.SH SEE ALSO
+.BR gettimeofday (2),
+.BR time (7)
diff --git a/man/man3/timerclear.3 b/man/man3/timerclear.3
new file mode 100644
index 000000000..8e977c98a
--- /dev/null
+++ b/man/man3/timerclear.3
@@ -0,0 +1 @@
+.so man3/timeradd.3
diff --git a/man/man3/timercmp.3 b/man/man3/timercmp.3
new file mode 100644
index 000000000..8e977c98a
--- /dev/null
+++ b/man/man3/timercmp.3
@@ -0,0 +1 @@
+.so man3/timeradd.3
diff --git a/man/man3/timerisset.3 b/man/man3/timerisset.3
new file mode 100644
index 000000000..8e977c98a
--- /dev/null
+++ b/man/man3/timerisset.3
@@ -0,0 +1 @@
+.so man3/timeradd.3
diff --git a/man/man3/timersub.3 b/man/man3/timersub.3
new file mode 100644
index 000000000..8e977c98a
--- /dev/null
+++ b/man/man3/timersub.3
@@ -0,0 +1 @@
+.so man3/timeradd.3
diff --git a/man/man3/timezone.3 b/man/man3/timezone.3
new file mode 100644
index 000000000..80907636c
--- /dev/null
+++ b/man/man3/timezone.3
@@ -0,0 +1 @@
+.so man3/tzset.3
diff --git a/man/man3/tmpfile.3 b/man/man3/tmpfile.3
new file mode 100644
index 000000000..1bfcdabf3
--- /dev/null
+++ b/man/man3/tmpfile.3
@@ -0,0 +1,103 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 17:46:57 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2001-11-17, aeb
+.TH tmpfile 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tmpfile \- create a temporary file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.B FILE *tmpfile(void);
+.fi
+.SH DESCRIPTION
+The
+.BR tmpfile ()
+function opens a unique temporary file
+in binary read/write (w+b) mode.
+The file will be automatically deleted when it is closed or the
+program terminates.
+.SH RETURN VALUE
+The
+.BR tmpfile ()
+function returns a stream descriptor, or NULL if
+a unique filename cannot be generated or the unique file cannot be
+opened.
+In the latter case,
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EACCES
+Search permission denied for directory in file's path prefix.
+.TP
+.B EEXIST
+Unable to generate a unique filename.
+.TP
+.B EINTR
+The call was interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EMFILE
+The per-process limit on the number of open file descriptors has been reached.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOSPC
+There was no room in the directory to add the new filename.
+.TP
+.B EROFS
+Read-only filesystem.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tmpfile ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The standard does not specify the directory that
+.BR tmpfile ()
+will use.
+glibc will try the path prefix
+.I P_tmpdir
+defined
+in
+.IR <stdio.h> ,
+and if that fails, then the directory
+.IR /tmp .
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, SVr4, 4.3BSD, SUSv2.
+.SH NOTES
+POSIX.1-2001 specifies:
+an error message may be written to
+.I stdout
+if the stream
+cannot be opened.
+.SH SEE ALSO
+.BR exit (3),
+.BR mkstemp (3),
+.BR mktemp (3),
+.BR tempnam (3),
+.BR tmpnam (3)
diff --git a/man/man3/tmpnam.3 b/man/man3/tmpnam.3
new file mode 100644
index 000000000..77ca78d90
--- /dev/null
+++ b/man/man3/tmpnam.3
@@ -0,0 +1,168 @@
+'\" t
+.\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2003-11-15, aeb, added tmpnam_r
+.\"
+.TH tmpnam 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tmpnam, tmpnam_r \- create a name for a temporary file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "[[deprecated]] char *tmpnam(char *" s );
+.BI "[[deprecated]] char *tmpnam_r(char *" s );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR tmpnam_r ()
+.nf
+    Since glibc 2.19:
+        _DEFAULT_SOURCE
+    Up to and including glibc 2.19:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+.B Note:
+avoid using these functions; use
+.BR mkstemp (3)
+or
+.BR tmpfile (3)
+instead.
+.P
+The
+.BR tmpnam ()
+function returns a pointer to a string that is a valid filename,
+and such that a file with this name did not exist at some point
+in time, so that naive programmers may think it
+a suitable name for a temporary file.
+If the argument
+.I s
+is NULL, this name is generated in an internal static buffer
+and may be overwritten by the next call to
+.BR tmpnam ().
+If
+.I s
+is not NULL, the name is copied to the character array (of length
+at least
+.IR L_tmpnam )
+pointed to by
+.I s
+and the value
+.I s
+is returned in case of success.
+.P
+The created pathname has a directory prefix
+.IR P_tmpdir .
+(Both
+.I L_tmpnam
+and
+.I P_tmpdir
+are defined in
+.IR <stdio.h> ,
+just like the
+.B TMP_MAX
+mentioned below.)
+.P
+The
+.BR tmpnam_r ()
+function performs the same task as
+.BR tmpnam (),
+but returns NULL (to indicate an error) if
+.I s
+is NULL.
+.SH RETURN VALUE
+These functions return a pointer to a unique temporary
+filename, or NULL if a unique name cannot be generated.
+.SH ERRORS
+No errors are defined.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tmpnam ()
+T}	Thread safety	MT-Unsafe race:tmpnam/!s
+T{
+.na
+.nh
+.BR tmpnam_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR tmpnam ()
+C11, POSIX.1-2008.
+.TP
+.BR tmpnam_r ()
+None.
+.SH HISTORY
+.TP
+.BR tmpnam ()
+SVr4, 4.3BSD, C89, POSIX.1-2001.
+Obsolete in POSIX.1-2008.
+.TP
+.BR tmpnam_r ()
+Solaris.
+.SH NOTES
+The
+.BR tmpnam ()
+function generates a different string each time it is called,
+up to
+.B TMP_MAX
+times.
+If it is called more than
+.B TMP_MAX
+times,
+the behavior is implementation defined.
+.P
+Although these functions generate names that are difficult to guess,
+it is nevertheless possible that between the time that
+the pathname is returned and the time that the program opens it,
+another program might create that pathname using
+.BR open (2),
+or create it as a symbolic link.
+This can lead to security holes.
+To avoid such possibilities, use the
+.BR open (2)
+.B O_EXCL
+flag to open the pathname.
+Or better yet, use
+.BR mkstemp (3)
+or
+.BR tmpfile (3).
+.P
+Portable applications that use threads cannot call
+.BR tmpnam ()
+with a NULL argument if either
+.B _POSIX_THREADS
+or
+.B _POSIX_THREAD_SAFE_FUNCTIONS
+is defined.
+.SH BUGS
+Never use these functions.
+Use
+.BR mkstemp (3)
+or
+.BR tmpfile (3)
+instead.
+.SH SEE ALSO
+.BR mkstemp (3),
+.BR mktemp (3),
+.BR tempnam (3),
+.BR tmpfile (3)
diff --git a/man/man3/tmpnam_r.3 b/man/man3/tmpnam_r.3
new file mode 100644
index 000000000..c1bd6dc1a
--- /dev/null
+++ b/man/man3/tmpnam_r.3
@@ -0,0 +1 @@
+.so man3/tmpnam.3
diff --git a/man/man3/toascii.3 b/man/man3/toascii.3
new file mode 100644
index 000000000..83075a888
--- /dev/null
+++ b/man/man3/toascii.3
@@ -0,0 +1,68 @@
+'\" t
+.\" Copyright (c) 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Added BUGS section, aeb, 950919
+.\"
+.TH toascii 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+toascii \- convert character to ASCII
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <ctype.h>
+.P
+.BI "[[deprecated]] int toascii(int " c );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR toascii ():
+.nf
+    _XOPEN_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+.BR toascii ()
+converts
+.I c
+to a 7-bit
+.I "unsigned char"
+value that fits into the ASCII character set, by clearing the
+high-order bits.
+.SH RETURN VALUE
+The value returned is that of the converted character.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR toascii ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+SVr4, BSD, POSIX.1-2001.
+Obsolete in POSIX.1-2008,
+noting that it cannot be used portably in a localized application.
+.SH BUGS
+Many people will be unhappy if you use this function.
+This function will convert accented letters into random characters.
+.SH SEE ALSO
+.BR isascii (3),
+.BR tolower (3),
+.BR toupper (3)
diff --git a/man/man3/tolower.3 b/man/man3/tolower.3
new file mode 100644
index 000000000..033f16e9e
--- /dev/null
+++ b/man/man3/tolower.3
@@ -0,0 +1 @@
+.so man3/toupper.3
diff --git a/man/man3/tolower_l.3 b/man/man3/tolower_l.3
new file mode 100644
index 000000000..033f16e9e
--- /dev/null
+++ b/man/man3/tolower_l.3
@@ -0,0 +1 @@
+.so man3/toupper.3
diff --git a/man/man3/toupper.3 b/man/man3/toupper.3
new file mode 100644
index 000000000..98a111c81
--- /dev/null
+++ b/man/man3/toupper.3
@@ -0,0 +1,185 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 17:45:39 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2000-02-13 by Nicolás Lichtmaier <nick@debian.org>
+.TH toupper 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+toupper, tolower, toupper_l, tolower_l \- convert uppercase or lowercase
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <ctype.h>
+.P
+.BI "int toupper(int " "c" );
+.BI "int tolower(int " "c" );
+.P
+.BI "int toupper_l(int " c ", locale_t " locale );
+.BI "int tolower_l(int " c ", locale_t " locale );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR toupper_l (),
+.BR tolower_l ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+These functions convert lowercase letters to uppercase, and vice versa.
+.P
+If
+.I c
+is a lowercase letter,
+.BR toupper ()
+returns its uppercase equivalent,
+if an uppercase representation exists in the current locale.
+Otherwise, it returns
+.IR c .
+The
+.BR toupper_l ()
+function performs the same task,
+but uses the locale referred to by the locale handle
+.IR locale .
+.P
+If
+.I c
+is an uppercase letter,
+.BR tolower ()
+returns its lowercase equivalent,
+if a lowercase representation exists in the current locale.
+Otherwise, it returns
+.IR c .
+The
+.BR tolower_l ()
+function performs the same task,
+but uses the locale referred to by the locale handle
+.IR locale .
+.P
+If
+.I c
+is neither an
+.I "unsigned char"
+value nor
+.BR EOF ,
+the behavior of these functions
+is undefined.
+.P
+The behavior of
+.BR toupper_l ()
+and
+.BR tolower_l ()
+is undefined if
+.I locale
+is the special locale object
+.B LC_GLOBAL_LOCALE
+(see
+.BR duplocale (3))
+or is not a valid locale object handle.
+.SH RETURN VALUE
+The value returned is that of the converted letter, or
+.I c
+if the conversion was not possible.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR toupper (),
+.BR tolower (),
+.BR toupper_l (),
+.BR tolower_l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR toupper ()
+.TQ
+.BR tolower ()
+C11, POSIX.1-2008.
+.TP
+.BR toupper_l ()
+.TQ
+.BR tolower_l ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR toupper ()
+.TQ
+.BR tolower ()
+C89, 4.3BSD, POSIX.1-2001.
+.TP
+.BR toupper_l ()
+.TQ
+.BR tolower_l ()
+POSIX.1-2008.
+.SH NOTES
+The standards require that the argument
+.I c
+for these functions is either
+.B EOF
+or a value that is representable in the type
+.IR "unsigned char" .
+If the argument
+.I c
+is of type
+.IR char ,
+it must be cast to
+.IR "unsigned char" ,
+as in the following example:
+.P
+.in +4n
+.EX
+char c;
+\&...
+res = toupper((unsigned char) c);
+.EE
+.in
+.P
+This is necessary because
+.I char
+may be the equivalent
+.IR "signed char" ,
+in which case a byte where the top bit is set would be sign extended when
+converting to
+.IR int ,
+yielding a value that is outside the range of
+.IR "unsigned char" .
+.P
+The details of what constitutes an uppercase or lowercase letter depend
+on the locale.
+For example, the default
+.B \[dq]C\[dq]
+locale does not know about umlauts, so no conversion is done for them.
+.P
+In some non-English locales, there are lowercase letters with no
+corresponding uppercase equivalent;
+.\" FIXME One day the statement about "sharp s" needs to be reworked,
+.\" since there is nowadays a capital "sharp s" that has a codepoint
+.\" in Unicode 5.0; see https://en.wikipedia.org/wiki/Capital_%E1%BA%9E
+the German sharp s is one example.
+.SH SEE ALSO
+.BR isalpha (3),
+.BR newlocale (3),
+.BR setlocale (3),
+.BR towlower (3),
+.BR towupper (3),
+.BR uselocale (3),
+.BR locale (7)
diff --git a/man/man3/toupper_l.3 b/man/man3/toupper_l.3
new file mode 100644
index 000000000..033f16e9e
--- /dev/null
+++ b/man/man3/toupper_l.3
@@ -0,0 +1 @@
+.so man3/toupper.3
diff --git a/man/man3/towctrans.3 b/man/man3/towctrans.3
new file mode 100644
index 000000000..cca9f7de7
--- /dev/null
+++ b/man/man3/towctrans.3
@@ -0,0 +1,82 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH towctrans 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+towctrans \- wide-character transliteration
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "wint_t towctrans(wint_t " wc ", wctrans_t " desc );
+.fi
+.SH DESCRIPTION
+If
+.I wc
+is a wide character, then the
+.BR towctrans ()
+function
+translates it according to the transliteration descriptor
+.IR desc .
+If
+.I wc
+is
+.BR WEOF ,
+.B WEOF
+is returned.
+.P
+.I desc
+must be a transliteration descriptor returned by
+the
+.BR wctrans (3)
+function.
+.SH RETURN VALUE
+The
+.BR towctrans ()
+function returns the translated wide character,
+or
+.B WEOF
+if
+.I wc
+is
+.BR WEOF .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR towctrans ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR towctrans ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR towlower (3),
+.BR towupper (3),
+.BR wctrans (3)
diff --git a/man/man3/towlower.3 b/man/man3/towlower.3
new file mode 100644
index 000000000..c40046a38
--- /dev/null
+++ b/man/man3/towlower.3
@@ -0,0 +1,131 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH towlower 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+towlower, towlower_l \- convert a wide character to lowercase
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "wint_t towlower(wint_t " wc );
+.BI "wint_t towlower_l(wint_t " wc ", locale_t " locale );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR towlower_l ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR towlower ()
+function is the wide-character equivalent of the
+.BR tolower (3)
+function.
+If
+.I wc
+is an uppercase wide character,
+and there exists a lowercase equivalent in the current locale,
+it returns the lowercase equivalent of
+.IR wc .
+In all other cases,
+.I wc
+is returned unchanged.
+.P
+The
+.BR towlower_l ()
+function performs the same task,
+but performs the conversion based on the character type information in
+the locale specified by
+.IR locale .
+The behavior of
+.BR towlower_l ()
+is undefined if
+.I locale
+is the special locale object
+.B LC_GLOBAL_LOCALE
+(see
+.BR duplocale (3))
+or is not a valid locale object handle.
+.P
+The argument
+.I wc
+must be representable as a
+.I wchar_t
+and be a valid character in the locale or be the value
+.BR WEOF .
+.SH RETURN VALUE
+If
+.I wc
+was convertible to lowercase,
+.BR towlower ()
+returns its lowercase equivalent;
+otherwise it returns
+.IR wc .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR towlower ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR towlower_l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR towlower ()
+C11, POSIX.1-2008 (XSI).
+.TP
+.BR towlower_l ()
+POSIX.1-2008.
+.SH STANDARDS
+.TP
+.BR towlower ()
+C99, POSIX.1-2001 (XSI).
+Obsolete in POSIX.1-2008 (XSI).
+.TP
+.BR towlower_l ()
+glibc 2.3.
+POSIX.1-2008.
+.SH NOTES
+The behavior of these functions depends on the
+.B LC_CTYPE
+category of the locale.
+.P
+These functions are not very appropriate for dealing with Unicode characters,
+because Unicode knows about three cases: upper, lower, and title case.
+.SH SEE ALSO
+.BR iswlower (3),
+.BR towctrans (3),
+.BR towupper (3),
+.BR locale (7)
diff --git a/man/man3/towlower_l.3 b/man/man3/towlower_l.3
new file mode 100644
index 000000000..6135f865c
--- /dev/null
+++ b/man/man3/towlower_l.3
@@ -0,0 +1 @@
+.so man3/towlower.3
diff --git a/man/man3/towupper.3 b/man/man3/towupper.3
new file mode 100644
index 000000000..4393f6964
--- /dev/null
+++ b/man/man3/towupper.3
@@ -0,0 +1,130 @@
+'\" t
+.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH towupper 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+towupper, towupper_l \- convert a wide character to uppercase
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "wint_t towupper(wint_t " wc );
+.BI "wint_t towupper_l(wint_t " wc ", locale_t " locale );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR towupper_l ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR towupper ()
+function is the wide-character equivalent of the
+.BR toupper (3)
+function.
+If
+.I wc
+is a lowercase wide character,
+and there exists an uppercase equivalent in the current locale,
+it returns the uppercase equivalent of
+.IR wc .
+In all other cases,
+.I wc
+is returned unchanged.
+.P
+The
+.BR towupper_l ()
+function performs the same task,
+but performs the conversion based on the character type information in
+the locale specified by
+.IR locale .
+The behavior of
+.BR towupper_l ()
+is undefined if
+.I locale
+is the special locale object
+.B LC_GLOBAL_LOCALE
+(see
+.BR duplocale (3))
+or is not a valid locale object handle.
+.P
+The argument
+.I wc
+must be representable as a
+.I wchar_t
+and be a valid character in the locale or be the value
+.BR WEOF .
+.SH RETURN VALUE
+If
+.I wc
+was convertible to uppercase,
+.BR towupper ()
+returns its uppercase equivalent;
+otherwise it returns
+.IR wc .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR towupper ()
+T}	Thread safety	MT-Safe locale
+T{
+.na
+.nh
+.BR towupper_l ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR towupper ()
+C11, POSIX.1-2008 (XSI).
+.TP
+.BR towupper_l ()
+POSIX.1-2008.
+.SH HISTORY
+.TP
+.BR towupper ()
+C99, POSIX.1-2001 (XSI).
+Obsolete in POSIX.1-2008 (XSI).
+.TP
+.BR towupper_l ()
+POSIX.1-2008.
+glibc 2.3.
+.SH NOTES
+The behavior of these functions depends on the
+.B LC_CTYPE
+category of the locale.
+.P
+These functions are not very appropriate for dealing with Unicode characters,
+because Unicode knows about three cases: upper, lower, and title case.
+.SH SEE ALSO
+.BR iswupper (3),
+.BR towctrans (3),
+.BR towlower (3),
+.BR locale (7)
diff --git a/man/man3/towupper_l.3 b/man/man3/towupper_l.3
new file mode 100644
index 000000000..a0b0e89f8
--- /dev/null
+++ b/man/man3/towupper_l.3
@@ -0,0 +1 @@
+.so man3/towupper.3
diff --git a/man/man3/trunc.3 b/man/man3/trunc.3
new file mode 100644
index 000000000..bb8758fb1
--- /dev/null
+++ b/man/man3/trunc.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH trunc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+trunc, truncf, truncl \- round to integer, toward zero
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double trunc(double " x );
+.BI "float truncf(float " x );
+.BI "long double truncl(long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR trunc (),
+.BR truncf (),
+.BR truncl ():
+.nf
+    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+These functions round
+.I x
+to the nearest integer value that is not larger in magnitude than
+.IR x .
+.SH RETURN VALUE
+These functions return the rounded integer value, in floating format.
+.P
+If
+.I x
+is integral, infinite, or NaN,
+.I x
+itself is returned.
+.SH ERRORS
+No errors occur.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR trunc (),
+.BR truncf (),
+.BR truncl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+C99, POSIX.1-2001.
+.SH NOTES
+The integral value returned by these functions may be too large
+to store in an integer type
+.RI ( int ,
+.IR long ,
+etc.).
+To avoid an overflow, which will produce undefined results,
+an application should perform a range check on the returned value
+before assigning it to an integer type.
+.SH SEE ALSO
+.BR ceil (3),
+.BR floor (3),
+.BR lrint (3),
+.BR nearbyint (3),
+.BR rint (3),
+.BR round (3)
diff --git a/man/man3/truncf.3 b/man/man3/truncf.3
new file mode 100644
index 000000000..b85934168
--- /dev/null
+++ b/man/man3/truncf.3
@@ -0,0 +1 @@
+.so man3/trunc.3
diff --git a/man/man3/truncl.3 b/man/man3/truncl.3
new file mode 100644
index 000000000..b85934168
--- /dev/null
+++ b/man/man3/truncl.3
@@ -0,0 +1 @@
+.so man3/trunc.3
diff --git a/man/man3/tsearch.3 b/man/man3/tsearch.3
new file mode 100644
index 000000000..68e4e04f8
--- /dev/null
+++ b/man/man3/tsearch.3
@@ -0,0 +1,356 @@
+'\" t
+.\" Copyright 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH tsearch 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tsearch, tfind, tdelete, twalk, twalk_r, tdestroy \- manage a binary search tree
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <search.h>
+.P
+.B typedef enum { preorder, postorder, endorder, leaf } VISIT;
+.P
+.BI "void *tsearch(const void *" key ", void **" rootp ,
+.BI "                int (*" compar ")(const void *, const void *));"
+.BI "void *tfind(const void *" key ", void *const *" rootp ,
+.BI "                int (*" compar ")(const void *, const void *));"
+.BI "void *tdelete(const void *restrict " key ", void **restrict " rootp ,
+.BI "                int (*" compar ")(const void *, const void *));"
+.BI "void twalk(const void *" root ,
+.BI "                void (*" action ")(const void *" nodep ", VISIT " which ,
+.BI "                               int " depth ));
+.P
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <search.h>
+.P
+.BI "void twalk_r(const void *" root ,
+.BI "                void (*" action ")(const void *" nodep ", VISIT " which ,
+.BI "                               void *" closure ),
+.BI "                void *" closure );
+.BI "void tdestroy(void *" root ", void (*" free_node ")(void *" nodep ));
+.fi
+.SH DESCRIPTION
+.BR tsearch (),
+.BR tfind (),
+.BR twalk (),
+and
+.BR tdelete ()
+manage a
+binary search tree.
+They are generalized from Knuth (6.2.2) Algorithm T.
+The first field in each node of the tree is a pointer to the
+corresponding data item.
+(The calling program must store the actual data.)
+.I compar
+points to a comparison routine, which takes
+pointers to two items.
+It should return an integer which is negative,
+zero, or positive, depending on whether the first item is less than,
+equal to, or greater than the second.
+.P
+.BR tsearch ()
+searches the tree for an item.
+.I key
+points to the item to be searched for.
+.I rootp
+points to a variable which points to the root of the tree.
+If the tree is empty,
+then the variable that
+.I rootp
+points to should be set to NULL.
+If the item is found in the tree, then
+.BR tsearch ()
+returns a pointer
+to the corresponding tree node.
+(In other words,
+.BR tsearch ()
+returns a pointer to a pointer to the data item.)
+If the item is not found, then
+.BR tsearch ()
+adds it, and returns a
+pointer to the corresponding tree node.
+.P
+.BR tfind ()
+is like
+.BR tsearch (),
+except that if the item is not
+found, then
+.BR tfind ()
+returns NULL.
+.P
+.BR tdelete ()
+deletes an item from the tree.
+Its arguments are the same as for
+.BR tsearch ().
+.P
+.BR twalk ()
+performs depth-first, left-to-right traversal of a binary
+tree.
+.I root
+points to the starting node for the traversal.
+If that node is not the root, then only part of the tree will be visited.
+.BR twalk ()
+calls the user function
+.I action
+each time a node is
+visited (that is, three times for an internal node, and once for a
+leaf).
+.IR action ,
+in turn, takes three arguments.
+The first argument is a pointer to the node being visited.
+The structure of the node is unspecified,
+but it is possible to cast the pointer to a pointer-to-pointer-to-element
+in order to access the element stored within the node.
+The application must not modify the structure pointed to by this argument.
+The second argument is an integer which
+takes one of the values
+.BR preorder ,
+.BR postorder ,
+or
+.B endorder
+depending on whether this is the first, second, or
+third visit to the internal node,
+or the value
+.B leaf
+if this is the single visit to a leaf node.
+(These symbols are defined in
+.IR <search.h> .)
+The third argument is the depth of the node;
+the root node has depth zero.
+.P
+(More commonly,
+.BR preorder ,
+.BR postorder ,
+and
+.B endorder
+are known as
+.BR preorder ,
+.BR inorder ,
+and
+.BR postorder :
+before visiting the children, after the first and before the second,
+and after visiting the children.
+Thus, the choice of name
+.B post\%order
+is rather confusing.)
+.P
+.BR twalk_r ()
+is similar to
+.BR twalk (),
+but instead of the
+.I depth
+argument, the
+.I closure
+argument pointer is passed to each invocation of the action callback,
+unchanged.
+This pointer can be used to pass information to and from
+the callback function in a thread-safe fashion, without resorting
+to global variables.
+.P
+.BR tdestroy ()
+removes the whole tree pointed to by
+.IR root ,
+freeing all resources allocated by the
+.BR tsearch ()
+function.
+For the data in each tree node the function
+.I free_node
+is called.
+The pointer to the data is passed as the argument to the function.
+If no such work is necessary,
+.I free_node
+must point to a function
+doing nothing.
+.SH RETURN VALUE
+.BR tsearch ()
+returns a pointer to a matching node in the tree, or to
+the newly added node, or NULL if there was insufficient memory
+to add the item.
+.BR tfind ()
+returns a pointer to the node, or
+NULL if no match is found.
+If there are multiple items that match the key,
+the item whose node is returned is unspecified.
+.P
+.BR tdelete ()
+returns a pointer to the parent of the node deleted, or
+NULL if the item was not found.
+If the deleted node was the root node,
+.BR tdelete ()
+returns a dangling pointer that must not be accessed.
+.P
+.BR tsearch (),
+.BR tfind (),
+and
+.BR tdelete ()
+also
+return NULL if
+.I rootp
+was NULL on entry.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tsearch (),
+.BR tfind (),
+.BR tdelete ()
+T}	Thread safety	MT-Safe race:rootp
+T{
+.na
+.nh
+.BR twalk ()
+T}	Thread safety	MT-Safe race:root
+T{
+.na
+.nh
+.BR twalk_r ()
+T}	Thread safety	MT-Safe race:root
+T{
+.na
+.nh
+.BR tdestroy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR tsearch ()
+.TQ
+.BR tfind ()
+.TQ
+.BR tdelete ()
+.TQ
+.BR twalk ()
+POSIX.1-2008.
+.TP
+.BR tdestroy ()
+.TQ
+.BR twalk_r ()
+GNU.
+.SH HISTORY
+.TP
+.BR tsearch ()
+.TQ
+.BR tfind ()
+.TQ
+.BR tdelete ()
+.TQ
+.BR twalk ()
+POSIX.1-2001, POSIX.1-2008, SVr4.
+.TP
+.BR twalk_r ()
+glibc 2.30.
+.SH NOTES
+.BR twalk ()
+takes a pointer to the root, while the other functions
+take a pointer to a variable which points to the root.
+.P
+.BR tdelete ()
+frees the memory required for the node in the tree.
+The user is responsible for freeing the memory for the corresponding
+data.
+.P
+The example program depends on the fact that
+.BR twalk ()
+makes no
+further reference to a node after calling the user function with
+argument "endorder" or "leaf".
+This works with the GNU library
+implementation, but is not in the System V documentation.
+.SH EXAMPLES
+The following program inserts twelve random numbers into a binary
+tree, where duplicate numbers are collapsed, then prints the numbers
+in order.
+.P
+.\" SRC BEGIN (tsearch.c)
+.EX
+#define _GNU_SOURCE     /* Expose declaration of tdestroy() */
+#include <search.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+\&
+static void *root = NULL;
+\&
+static void *
+xmalloc(size_t n)
+{
+    void *p;
+\&
+    p = malloc(n);
+    if (p)
+        return p;
+    fprintf(stderr, "insufficient memory\en");
+    exit(EXIT_FAILURE);
+}
+\&
+static int
+compare(const void *pa, const void *pb)
+{
+    if (*(int *) pa < *(int *) pb)
+        return \-1;
+    if (*(int *) pa > *(int *) pb)
+        return 1;
+    return 0;
+}
+\&
+static void
+action(const void *nodep, VISIT which, int depth)
+{
+    int *datap;
+\&
+    switch (which) {
+    case preorder:
+        break;
+    case postorder:
+        datap = *(int **) nodep;
+        printf("%6d\en", *datap);
+        break;
+    case endorder:
+        break;
+    case leaf:
+        datap = *(int **) nodep;
+        printf("%6d\en", *datap);
+        break;
+    }
+}
+\&
+int
+main(void)
+{
+    int  *ptr;
+    int  **val;
+\&
+    srand(time(NULL));
+    for (unsigned int i = 0; i < 12; i++) {
+        ptr = xmalloc(sizeof(*ptr));
+        *ptr = rand() & 0xff;
+        val = tsearch(ptr, &root, compare);
+        if (val == NULL)
+            exit(EXIT_FAILURE);
+        if (*val != ptr)
+            free(ptr);
+    }
+    twalk(root, action);
+    tdestroy(root, free);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR bsearch (3),
+.BR hsearch (3),
+.BR lsearch (3),
+.BR qsort (3)
diff --git a/man/man3/ttyname.3 b/man/man3/ttyname.3
new file mode 100644
index 000000000..83f27a9dc
--- /dev/null
+++ b/man/man3/ttyname.3
@@ -0,0 +1,111 @@
+'\" t
+.\" Copyright (c) 1995 Jim Van Zandt <jrv@vanzandt.mv.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 2001-12-13, Martin Schulze <joey@infodrom.org>
+.\" Added ttyname_r, aeb, 2002-07-20
+.\"
+.TH ttyname 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ttyname, ttyname_r \- return name of a terminal
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <unistd.h>
+.P
+.BI "char *ttyname(int " fd );
+.BI "int ttyname_r(int " fd ", char " buf [. buflen "], size_t " buflen );
+.fi
+.SH DESCRIPTION
+The function
+.BR ttyname ()
+returns a pointer to the null-terminated pathname of the terminal device
+that is open on the file descriptor \fIfd\fP, or NULL on error
+(for example, if \fIfd\fP is not connected to a terminal).
+The return value may point to static data, possibly overwritten by the
+next call.
+The function
+.BR ttyname_r ()
+stores this pathname in the buffer
+.I buf
+of length
+.IR buflen .
+.SH RETURN VALUE
+The function
+.BR ttyname ()
+returns a pointer to a pathname on success.
+On error, NULL is returned, and
+.I errno
+is set to indicate the error.
+The function
+.BR ttyname_r ()
+returns 0 on success, and an error number upon error.
+.SH ERRORS
+.TP
+.B EBADF
+Bad file descriptor.
+.TP
+.\" glibc commit 15e9a4f378c8607c2ae1aa465436af4321db0e23
+.B ENODEV
+.I fd
+refers to a slave pseudoterminal device
+but the corresponding pathname could not be found (see NOTES).
+.TP
+.B ENOTTY
+.I fd
+does not refer to a terminal device.
+.TP
+.B ERANGE
+.RB ( ttyname_r ())
+.I buflen
+was too small to allow storing the pathname.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ttyname ()
+T}	Thread safety	MT-Unsafe race:ttyname
+T{
+.na
+.nh
+.BR ttyname_r ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, 4.2BSD.
+.SH NOTES
+A process that keeps a file descriptor that refers to a
+.BR pts (4)
+device open when switching to another mount namespace that uses a different
+.I /dev/ptmx
+instance may still accidentally find that a device path of the same name
+for that file descriptor exists.
+However, this device path refers to a different device and thus
+can't be used to access the device that the file descriptor refers to.
+Calling
+.BR ttyname ()
+or
+.BR ttyname_r ()
+on the file descriptor in the new mount namespace will cause these
+functions to return NULL and set
+.I errno
+to
+.BR ENODEV .
+.SH SEE ALSO
+.BR tty (1),
+.BR fstat (2),
+.BR ctermid (3),
+.BR isatty (3),
+.BR pts (4)
diff --git a/man/man3/ttyname_r.3 b/man/man3/ttyname_r.3
new file mode 100644
index 000000000..aaa18ee8b
--- /dev/null
+++ b/man/man3/ttyname_r.3
@@ -0,0 +1 @@
+.so man3/ttyname.3
diff --git a/man/man3/ttyslot.3 b/man/man3/ttyslot.3
new file mode 100644
index 000000000..358ae5584
--- /dev/null
+++ b/man/man3/ttyslot.3
@@ -0,0 +1,169 @@
+'\" t
+.\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" This replaces an earlier man page written by Walter Harms
+.\" <walter.harms@informatik.uni-oldenburg.de>.
+.\"
+.TH ttyslot 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ttyslot \- find the slot of the current user's terminal in some file
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <unistd.h>" "       /* See NOTES */"
+.P
+.B "int ttyslot(void);"
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ttyslot ():
+.nf
+    Since glibc 2.24:
+        _DEFAULT_SOURCE
+    From glibc 2.20 to glibc 2.23:
+        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.fi
+.SH DESCRIPTION
+The legacy function
+.BR ttyslot ()
+returns the index of the current user's entry in some file.
+.P
+Now "What file?" you ask.
+Well, let's first look at some history.
+.SS Ancient history
+There used to be a file
+.I /etc/ttys
+in UNIX\ V6, that was read by the
+.BR init (1)
+program to find out what to do with each terminal line.
+Each line consisted of three characters.
+The first character was either \[aq]0\[aq] or \[aq]1\[aq],
+where \[aq]0\[aq] meant "ignore".
+The second character denoted the terminal: \[aq]8\[aq] stood for "/dev/tty8".
+The third character was an argument to
+.BR getty (8)
+indicating the sequence of line speeds to try (\[aq]\-\[aq] was: start trying
+110 baud).
+Thus a typical line was "18\-".
+A hang on some line was solved by changing the \[aq]1\[aq] to a \[aq]0\[aq],
+signaling init, changing back again, and signaling init again.
+.P
+In UNIX\ V7 the format was changed: here the second character
+was the argument to
+.BR getty (8)
+indicating the sequence of line speeds to try (\[aq]0\[aq] was: cycle through
+300-1200-150-110 baud; \[aq]4\[aq] was for the on-line console DECwriter)
+while the rest of the line contained the name of the tty.
+Thus a typical line was "14console".
+.P
+Later systems have more elaborate syntax.
+System V-like systems have
+.I /etc/inittab
+instead.
+.SS Ancient history (2)
+On the other hand, there is the file
+.I /etc/utmp
+listing the people currently logged in.
+It is maintained by
+.BR login (1).
+It has a fixed size, and the appropriate index in the file was
+determined by
+.BR login (1)
+using the
+.BR ttyslot ()
+call to find the number of the line in
+.I /etc/ttys
+(counting from 1).
+.SS The semantics of ttyslot
+Thus, the function
+.BR ttyslot ()
+returns the index of the controlling terminal of the calling process
+in the file
+.IR /etc/ttys ,
+and that is (usually) the same as the index of the entry for the
+current user in the file
+.IR /etc/utmp .
+BSD still has the
+.I /etc/ttys
+file, but System V-like systems do not, and hence cannot refer to it.
+Thus, on such systems the documentation says that
+.BR ttyslot ()
+returns the current user's index in the user accounting data base.
+.SH RETURN VALUE
+If successful, this function returns the slot number.
+On error (e.g., if none of the file descriptors 0, 1, or 2 is
+associated with a terminal that occurs in this data base)
+it returns 0 on UNIX\ V6 and V7 and BSD-like systems,
+but \-1 on System V-like systems.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ttyslot ()
+T}	Thread safety	MT-Unsafe
+.TE
+.SH VERSIONS
+The utmp file is found in various places on various systems, such as
+.IR /etc/utmp ,
+.IR /var/adm/utmp ,
+.IR /var/run/utmp .
+.SH STANDARDS
+None.
+.SH HISTORY
+SUSv1; marked as LEGACY in SUSv2; removed in POSIX.1-2001.
+SUSv2 requires \-1 on error.
+.P
+The glibc2 implementation of this function reads the file
+.BR _PATH_TTYS ,
+defined in
+.I <ttyent.h>
+as "/etc/ttys".
+It returns 0 on error.
+Since Linux systems do not usually have "/etc/ttys", it will
+always return 0.
+.P
+On BSD-like systems and Linux, the declaration of
+.BR ttyslot ()
+is provided by
+.IR <unistd.h> .
+On System V-like systems, the declaration is provided by
+.IR <stdlib.h> .
+Since glibc 2.24,
+.I <stdlib.h>
+also provides the declaration with the following
+feature test macro definitions:
+.P
+.in +4n
+.EX
+(_XOPEN_SOURCE >= 500 ||
+        (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED))
+    && ! (_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
+.EE
+.in
+.P
+Minix also has
+.IR fttyslot ( fd ).
+.\" .SH HISTORY
+.\" .BR ttyslot ()
+.\" appeared in UNIX V7.
+.SH SEE ALSO
+.BR getttyent (3),
+.BR ttyname (3),
+.BR utmp (5)
diff --git a/man/man3/twalk.3 b/man/man3/twalk.3
new file mode 100644
index 000000000..72f125195
--- /dev/null
+++ b/man/man3/twalk.3
@@ -0,0 +1 @@
+.so man3/tsearch.3
diff --git a/man/man3/twalk_r.3 b/man/man3/twalk_r.3
new file mode 100644
index 000000000..72f125195
--- /dev/null
+++ b/man/man3/twalk_r.3
@@ -0,0 +1 @@
+.so man3/tsearch.3
diff --git a/man/man3/tzname.3 b/man/man3/tzname.3
new file mode 100644
index 000000000..80907636c
--- /dev/null
+++ b/man/man3/tzname.3
@@ -0,0 +1 @@
+.so man3/tzset.3
diff --git a/man/man3/tzset.3 b/man/man3/tzset.3
new file mode 100644
index 000000000..8479b17b0
--- /dev/null
+++ b/man/man3/tzset.3
@@ -0,0 +1,244 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sun Jul 25 11:01:58 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2001-11-13, aeb
+.\" Modified 2004-12-01 mtk and Martin Schulze <joey@infodrom.org>
+.\"
+.TH tzset 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tzset, tzname, timezone, daylight \- initialize time conversion information
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.B void tzset(void);
+.P
+.BI "extern char *" tzname [2];
+.BI "extern long " timezone ;
+.BI "extern int " daylight ;
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR tzset ():
+.nf
+    _POSIX_C_SOURCE
+.fi
+.P
+.IR tzname :
+.nf
+    _POSIX_C_SOURCE
+.fi
+.P
+.IR timezone ,
+.IR daylight :
+.nf
+    _XOPEN_SOURCE
+        || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR tzset ()
+function initializes the \fItzname\fP variable from the
+.B TZ
+environment variable.
+This function is automatically called by the
+other time conversion functions that depend on the timezone.
+In a System-V-like environment, it will also set the variables \fItimezone\fP
+(seconds West of UTC) and \fIdaylight\fP (to 0 if this timezone does not
+have any daylight saving time rules, or to nonzero if there is a time,
+past, present, or future when daylight saving time applies).
+.P
+If the
+.B TZ
+variable does not appear in the environment, the system timezone is used.
+The system timezone is configured by copying, or linking, a file in the
+.BR tzfile (5)
+format to
+.IR /etc/localtime .
+A timezone database of these files may be located in the system
+timezone directory (see the \fBFILES\fP section below).
+.P
+If the
+.B TZ
+variable does appear in the environment, but its value is empty,
+or its value cannot be interpreted using any of the formats specified
+below, then Coordinated Universal Time (UTC) is used.
+.P
+The value of
+.B TZ
+can be one of two formats.
+The first format is a string of characters that directly represent the
+timezone to be used:
+.P
+.in +4n
+.EX
+.IR "std offset" [ dst [ offset ][, start [ /time ], end [ /time ]]]
+.EE
+.in
+.P
+There are no spaces in the specification.
+The \fIstd\fP string specifies an abbreviation for the timezone and must be
+three or more alphabetic characters.
+When enclosed between the less-than (<) and greater-than (>) signs, the
+character set is expanded to include the plus (+) sign, the minus (\-)
+sign, and digits.
+The \fIoffset\fP string immediately
+follows \fIstd\fP and specifies the time value to be added to the local
+time to get Coordinated Universal Time (UTC).
+The \fIoffset\fP is positive
+if the local timezone is west of the Prime Meridian and negative if it is
+east.
+The hour must be between 0 and 24, and the minutes and seconds 00 and 59:
+.P
+.in +4n
+.EX
+.RI [ + | \- ] hh [ :mm [ :ss ]]
+.EE
+.in
+.P
+The \fIdst\fP string and \fIoffset\fP specify the name and offset for the
+corresponding daylight saving timezone.
+If the offset is omitted,
+it defaults to one hour ahead of standard time.
+.P
+The \fIstart\fP field specifies when daylight saving time goes into
+effect and the \fIend\fP field specifies when the change is made back to
+standard time.
+These fields may have the following formats:
+.TP
+J\fIn\fP
+This specifies the Julian day with \fIn\fP between 1 and 365.
+Leap days are not counted.
+In this format, February 29 can't be represented;
+February 28 is day 59, and March 1 is always day 60.
+.TP
+.I n
+This specifies the zero-based Julian day with \fIn\fP between 0 and 365.
+February 29 is counted in leap years.
+.TP
+M\fIm\fP.\fIw\fP.\fId\fP
+This specifies day \fId\fP (0 <= \fId\fP <= 6) of week \fIw\fP
+(1 <= \fIw\fP <= 5) of month \fIm\fP (1 <= \fIm\fP <= 12).
+Week 1 is
+the first week in which day \fId\fP occurs and week 5 is the last week
+in which day \fId\fP occurs.
+Day 0 is a Sunday.
+.P
+The \fItime\fP fields specify when, in the local time currently in effect,
+the change to the other time occurs.
+If omitted, the default is 02:00:00.
+.P
+Here is an example for New Zealand,
+where the standard time (NZST) is 12 hours ahead of UTC,
+and daylight saving time (NZDT), 13 hours ahead of UTC,
+runs from the first Sunday in October to the third Sunday in March,
+and the changeovers happen at the default time of 02:00:00:
+.P
+.in +4n
+.EX
+TZ="NZST\-12:00:00NZDT\-13:00:00,M10.1.0,M3.3.0"
+.EE
+.in
+.P
+The second format specifies that the timezone information should be read
+from a file:
+.P
+.in +4n
+.EX
+:[filespec]
+.EE
+.in
+.P
+If the file specification \fIfilespec\fP is omitted, or its value cannot
+be interpreted, then Coordinated Universal Time (UTC) is used.
+If \fIfilespec\fP is given, it specifies another
+.BR tzfile (5)-format
+file to read the timezone information from.
+If \fIfilespec\fP does not begin with a \[aq]/\[aq], the file specification is
+relative to the system timezone directory.
+If the colon is omitted each
+of the above \fBTZ\fP formats will be tried.
+.P
+Here's an example, once more for New Zealand:
+.P
+.in +4n
+.EX
+TZ=":Pacific/Auckland"
+.EE
+.in
+.SH ENVIRONMENT
+.TP
+.B TZ
+If this variable is set its value takes precedence over the system
+configured timezone.
+.TP
+.B TZDIR
+If this variable is set its value takes precedence over the system
+configured timezone database directory path.
+.SH FILES
+.TP
+.I /etc/localtime
+The system timezone file.
+.TP
+.I /usr/share/zoneinfo/
+The system timezone database directory.
+.TP
+.I /usr/share/zoneinfo/posixrules
+When a TZ string includes a dst timezone without anything following it,
+then this file is used for the start/end rules.
+It is in the
+.BR tzfile (5)
+format.
+By default, the zoneinfo Makefile hard links it to the
+.IR America/New_York " tzfile."
+.P
+Above are the current standard file locations, but they are
+configurable when glibc is compiled.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR tzset ()
+T}	Thread safety	MT-Safe env locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, SVr4, 4.3BSD.
+.P
+4.3BSD had a function
+.BI "char *timezone(" zone ", " dst )
+that returned the
+name of the timezone corresponding to its first argument (minutes
+West of UTC).
+If the second argument was 0, the standard name was used,
+otherwise the daylight saving time version.
+.SH SEE ALSO
+.BR date (1),
+.BR gettimeofday (2),
+.BR time (2),
+.BR ctime (3),
+.BR getenv (3),
+.BR tzfile (5)
diff --git a/man/man3/ualarm.3 b/man/man3/ualarm.3
new file mode 100644
index 000000000..4e63c0ce5
--- /dev/null
+++ b/man/man3/ualarm.3
@@ -0,0 +1,140 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ualarm 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ualarm \- schedule signal after given number of microseconds
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <unistd.h>"
+.P
+.BI "useconds_t ualarm(useconds_t " usecs ", useconds_t " interval );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR ualarm ():
+.nf
+    Since glibc 2.12:
+        (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE
+    Before glibc 2.12:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+The
+.BR ualarm ()
+function causes the signal
+.B SIGALRM
+to be sent to the invoking process after (not less than)
+.I usecs
+microseconds.
+The delay may be lengthened slightly by any system activity
+or by the time spent processing the call or by the
+granularity of system timers.
+.P
+Unless caught or ignored, the
+.B SIGALRM
+signal will terminate the process.
+.P
+If the
+.I interval
+argument is nonzero, further
+.B SIGALRM
+signals will be sent every
+.I interval
+microseconds after the first.
+.SH RETURN VALUE
+This function returns the number of microseconds remaining for
+any alarm that was previously set, or 0 if no alarm was pending.
+.SH ERRORS
+.TP
+.B EINTR
+Interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EINVAL
+\fIusecs\fP or \fIinterval\fP is not smaller than 1000000.
+(On systems where that is considered an error.)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ualarm ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD, POSIX.1-2001.
+POSIX.1-2001 marks it as obsolete.
+Removed in POSIX.1-2008.
+.P
+4.3BSD, SUSv2, and POSIX do not define any errors.
+.P
+POSIX.1-2001 does not specify what happens if the
+.I usecs
+argument is 0.
+.\" This case is not documented in HP-US, Solar, FreeBSD, NetBSD, or OpenBSD!
+On Linux (and probably most other systems),
+the effect is to cancel any pending alarm.
+.P
+The type
+.I useconds_t
+is an unsigned integer type capable of holding integers
+in the range [0,1000000].
+On the original BSD implementation, and in glibc before glibc 2.1,
+the arguments to
+.BR ualarm ()
+were instead typed as
+.IR "unsigned int" .
+Programs will be more portable if they never mention
+.I useconds_t
+explicitly.
+.P
+The interaction of this function with
+other timer functions such as
+.BR alarm (2),
+.BR sleep (3),
+.BR nanosleep (2),
+.BR setitimer (2),
+.BR timer_create (2),
+.BR timer_delete (2),
+.BR timer_getoverrun (2),
+.BR timer_gettime (2),
+.BR timer_settime (2),
+.BR usleep (3)
+is unspecified.
+.P
+This function is obsolete.
+Use
+.BR setitimer (2)
+or POSIX interval timers
+.RB ( timer_create (2),
+etc.)
+instead.
+.SH SEE ALSO
+.BR alarm (2),
+.BR getitimer (2),
+.BR nanosleep (2),
+.BR select (2),
+.BR setitimer (2),
+.BR usleep (3),
+.BR time (7)
diff --git a/man/man3/ulckpwdf.3 b/man/man3/ulckpwdf.3
new file mode 100644
index 000000000..142c5a5ca
--- /dev/null
+++ b/man/man3/ulckpwdf.3
@@ -0,0 +1 @@
+.so man3/getspnam.3
diff --git a/man/man3/ulimit.3 b/man/man3/ulimit.3
new file mode 100644
index 000000000..e4ed71205
--- /dev/null
+++ b/man/man3/ulimit.3
@@ -0,0 +1,87 @@
+'\" t
+.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Moved to man3, aeb, 980612
+.\"
+.TH ulimit 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ulimit \- get and set user limits
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <ulimit.h>
+.P
+.BI "[[deprecated]] long ulimit(int " cmd ", long " newlimit );
+.fi
+.SH DESCRIPTION
+Warning: this routine is obsolete.
+Use
+.BR getrlimit (2),
+.BR setrlimit (2),
+and
+.BR sysconf (3)
+instead.
+For the shell command
+.BR ulimit ,
+see
+.BR bash (1).
+.P
+The
+.BR ulimit ()
+call will get or set some limit for the calling process.
+The
+.I cmd
+argument can have one of the following values.
+.TP
+.B UL_GETFSIZE
+Return the limit on the size of a file, in units of 512 bytes.
+.TP
+.B UL_SETFSIZE
+Set the limit on the size of a file.
+.TP
+.B 3
+(Not implemented for Linux.)
+Return the maximum possible address of the data segment.
+.TP
+.B 4
+(Implemented but no symbolic constant provided.)
+Return the maximum number of files that the calling process can open.
+.SH RETURN VALUE
+On success,
+.BR ulimit ()
+returns a nonnegative value.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EPERM
+An unprivileged process tried to increase a limit.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ulimit ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+SVr4, POSIX.1-2001.
+POSIX.1-2008 marks it as obsolete.
+.SH SEE ALSO
+.BR bash (1),
+.BR getrlimit (2),
+.BR setrlimit (2),
+.BR sysconf (3)
diff --git a/man/man3/undocumented.3 b/man/man3/undocumented.3
new file mode 100644
index 000000000..bb025e848
--- /dev/null
+++ b/man/man3/undocumented.3
@@ -0,0 +1,164 @@
+.\" Copyright 1995 Jim Van Zandt
+.\" From jrv@vanzandt.mv.com Mon Sep  4 21:11:50 1995
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 1996-11-08, meem@sherilyn.wustl.edu, corrections
+.\" 2004-10-31, aeb, changed maintainer address, updated list
+.\" 2015-04-20, william@tuffbizz.com, updated list
+.\"
+.TH undocumented 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+undocumented \- undocumented library functions
+.SH SYNOPSIS
+.nf
+Undocumented library functions
+.fi
+.SH DESCRIPTION
+This man page mentions those library functions which are implemented in
+the standard libraries but not yet documented in man pages.
+.SS Solicitation
+If you have information about these functions,
+please look in the source code, write a man page (using a style
+similar to that of the other Linux section 3 man pages), and send it to
+.B mtk.manpages@gmail.com
+for inclusion in the next man page release.
+.SS The list
+.BR authdes_create (3),
+.BR authdes_getucred (3),
+.BR authdes_pk_create (3),
+.\" .BR chflags (3),
+.BR clntunix_create (3),
+.BR creat64 (3),
+.BR dn_skipname (3),
+.\" .BR fattach (3),
+.\" .BR fchflags (3),
+.\" .BR fclean (3),
+.BR fcrypt (3),
+.\" .BR fdetach (3),
+.BR fp_nquery (3),
+.BR fp_query (3),
+.BR fp_resstat (3),
+.BR freading (3),
+.BR freopen64 (3),
+.BR fseeko64 (3),
+.BR ftello64 (3),
+.BR ftw64 (3),
+.BR fwscanf (3),
+.BR get_avphys_pages (3),
+.BR getdirentries64 (3),
+.BR getmsg (3),
+.BR getnetname (3),
+.BR get_phys_pages (3),
+.BR getpublickey (3),
+.BR getsecretkey (3),
+.BR h_errlist (3),
+.BR host2netname (3),
+.BR hostalias (3),
+.BR inet_nsap_addr (3),
+.BR inet_nsap_ntoa (3),
+.BR init_des (3),
+.BR libc_nls_init (3),
+.BR mstats (3),
+.BR netname2host (3),
+.BR netname2user (3),
+.BR nlist (3),
+.BR obstack_free (3),
+.\" .BR obstack stuff (3),
+.BR parse_printf_format (3),
+.BR p_cdname (3),
+.BR p_cdnname (3),
+.BR p_class (3),
+.BR p_fqname (3),
+.BR p_option (3),
+.BR p_query (3),
+.BR printf_size (3),
+.BR printf_size_info (3),
+.BR p_rr (3),
+.BR p_time (3),
+.BR p_type (3),
+.BR putlong (3),
+.BR putshort (3),
+.BR re_compile_fastmap (3),
+.BR re_compile_pattern (3),
+.BR register_printf_function (3),
+.BR re_match (3),
+.BR re_match_2 (3),
+.BR re_rx_search (3),
+.BR re_search (3),
+.BR re_search_2 (3),
+.BR re_set_registers (3),
+.BR re_set_syntax (3),
+.BR res_send_setqhook (3),
+.BR res_send_setrhook (3),
+.BR ruserpass (3),
+.BR setfileno (3),
+.BR sethostfile (3),
+.BR svc_exit (3),
+.BR svcudp_enablecache (3),
+.BR tell (3),
+.BR thrd_create (3),
+.BR thrd_current (3),
+.BR thrd_equal (3),
+.BR thrd_sleep (3),
+.BR thrd_yield (3),
+.BR tr_break (3),
+.BR tzsetwall (3),
+.BR ufc_dofinalperm (3),
+.BR ufc_doit (3),
+.BR user2netname (3),
+.BR wcschrnul (3),
+.BR wcsftime (3),
+.BR wscanf (3),
+.BR xdr_authdes_cred (3),
+.BR xdr_authdes_verf (3),
+.BR xdr_cryptkeyarg (3),
+.BR xdr_cryptkeyres (3),
+.BR xdr_datum (3),
+.BR xdr_des_block (3),
+.BR xdr_domainname (3),
+.BR xdr_getcredres (3),
+.BR xdr_keybuf (3),
+.BR xdr_keystatus (3),
+.BR xdr_mapname (3),
+.BR xdr_netnamestr (3),
+.BR xdr_netobj (3),
+.BR xdr_passwd (3),
+.BR xdr_peername (3),
+.BR xdr_rmtcall_args (3),
+.BR xdr_rmtcallres (3),
+.BR xdr_unixcred (3),
+.BR xdr_yp_buf (3),
+.BR xdr_yp_inaddr (3),
+.BR xdr_ypbind_binding (3),
+.BR xdr_ypbind_resp (3),
+.BR xdr_ypbind_resptype (3),
+.BR xdr_ypbind_setdom (3),
+.BR xdr_ypdelete_args (3),
+.BR xdr_ypmaplist (3),
+.BR xdr_ypmaplist_str (3),
+.BR xdr_yppasswd (3),
+.BR xdr_ypreq_key (3),
+.BR xdr_ypreq_nokey (3),
+.BR xdr_ypresp_all (3),
+.BR xdr_ypresp_all_seq (3),
+.BR xdr_ypresp_key_val (3),
+.BR xdr_ypresp_maplist (3),
+.BR xdr_ypresp_master (3),
+.BR xdr_ypresp_order (3),
+.BR xdr_ypresp_val (3),
+.BR xdr_ypstat (3),
+.BR xdr_ypupdate_args (3),
+.BR yp_all (3),
+.BR yp_bind (3),
+.BR yperr_string (3),
+.BR yp_first (3),
+.BR yp_get_default_domain (3),
+.BR yp_maplist (3),
+.BR yp_master (3),
+.BR yp_match (3),
+.BR yp_next (3),
+.BR yp_order (3),
+.BR ypprot_err (3),
+.BR yp_unbind (3),
+.BR yp_update (3)
diff --git a/man/man3/ungetc.3 b/man/man3/ungetc.3
new file mode 100644
index 000000000..2f6585a10
--- /dev/null
+++ b/man/man3/ungetc.3
@@ -0,0 +1 @@
+.so man3/fgetc.3
diff --git a/man/man3/ungetwc.3 b/man/man3/ungetwc.3
new file mode 100644
index 000000000..896152e3f
--- /dev/null
+++ b/man/man3/ungetwc.3
@@ -0,0 +1,102 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH ungetwc 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ungetwc \- push back a wide character onto a FILE stream
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wint_t ungetwc(wint_t " wc ", FILE *" stream );
+.fi
+.SH DESCRIPTION
+The
+.BR ungetwc ()
+function is the wide-character equivalent of the
+.BR ungetc (3)
+function.
+It pushes back a wide character onto
+.I stream
+and returns it.
+.P
+If
+.I wc
+is
+.BR WEOF ,
+it returns
+.BR WEOF .
+If
+.I wc
+is an invalid wide character,
+it sets
+.I errno
+to
+.B EILSEQ
+and returns
+.BR WEOF .
+.P
+If
+.I wc
+is a valid wide character, it is pushed back onto the stream
+and thus becomes available for future wide-character read operations.
+The file-position indicator is decremented by one or more.
+The end-of-file
+indicator is cleared.
+The backing storage of the file is not affected.
+.P
+Note:
+.I wc
+need not be the last wide-character read from the stream;
+it can be any other valid wide character.
+.P
+If the implementation supports multiple push-back operations in a row, the
+pushed-back wide characters will be read in reverse order; however, only one
+level of push-back is guaranteed.
+.SH RETURN VALUE
+The
+.BR ungetwc ()
+function returns
+.I wc
+when successful, or
+.B WEOF
+upon
+failure.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR ungetwc ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR ungetwc ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR fgetwc (3)
diff --git a/man/man3/unlocked_stdio.3 b/man/man3/unlocked_stdio.3
new file mode 100644
index 000000000..1e16877e1
--- /dev/null
+++ b/man/man3/unlocked_stdio.3
@@ -0,0 +1,202 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH unlocked_stdio 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+getc_unlocked, getchar_unlocked, putc_unlocked,
+putchar_unlocked \- nonlocking stdio functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BI "int getc_unlocked(FILE *" stream );
+.B "int getchar_unlocked(void);"
+.BI "int putc_unlocked(int " c ", FILE *" stream );
+.BI "int putchar_unlocked(int " c );
+.P
+.BI "void clearerr_unlocked(FILE *" stream );
+.BI "int feof_unlocked(FILE *" stream );
+.BI "int ferror_unlocked(FILE *" stream );
+.BI "int fileno_unlocked(FILE *" stream );
+.BI "int fflush_unlocked(FILE *_Nullable " stream );
+.P
+.BI "int fgetc_unlocked(FILE *" stream );
+.BI "int fputc_unlocked(int " c ", FILE *" stream );
+.P
+.BI "size_t fread_unlocked(void " ptr "[restrict ." size " * ." n ],
+.BI "                      size_t " size ", size_t " n ,
+.BI "                      FILE *restrict " stream );
+.BI "size_t fwrite_unlocked(const void " ptr "[restrict ." size " * ." n ],
+.BI "                      size_t " size ", size_t " n ,
+.BI "                      FILE *restrict " stream );
+.P
+.BI "char *fgets_unlocked(char " s "[restrict ." n "], int " n \
+", FILE *restrict " stream );
+.BI "int fputs_unlocked(const char *restrict " s ", FILE *restrict " stream );
+.P
+.B #include <wchar.h>
+.P
+.BI "wint_t getwc_unlocked(FILE *" stream );
+.B "wint_t getwchar_unlocked(void);"
+.BI "wint_t fgetwc_unlocked(FILE *" stream );
+.P
+.BI "wint_t fputwc_unlocked(wchar_t " wc ", FILE *" stream );
+.BI "wint_t putwc_unlocked(wchar_t " wc ", FILE *" stream );
+.BI "wint_t putwchar_unlocked(wchar_t " wc );
+.P
+.BI "wchar_t *fgetws_unlocked(wchar_t " ws "[restrict ." n "], int " n ,
+.BI "                      FILE *restrict " stream );
+.BI "int fputws_unlocked(const wchar_t *restrict " ws ,
+.BI "                      FILE *restrict " stream );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR \%getc_unlocked (),
+.BR \%getchar_unlocked (),
+.BR \%putc_unlocked (),
+.BR \%putchar_unlocked ():
+.nf
+    /* glibc >= 2.24: */ _POSIX_C_SOURCE >= 199309L
+        || /* glibc <= 2.23: */ _POSIX_C_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.P
+.BR \%clearerr_unlocked (),
+.BR \%feof_unlocked (),
+.BR \%ferror_unlocked (),
+.BR \%fileno_unlocked (),
+.BR \%fflush_unlocked (),
+.BR \%fgetc_unlocked (),
+.BR \%fputc_unlocked (),
+.BR \%fread_unlocked (),
+.BR \%fwrite_unlocked ():
+.nf
+    /* glibc >= 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.P
+.BR \%fgets_unlocked (),
+.BR \%fputs_unlocked (),
+.BR \%getwc_unlocked (),
+.BR \%getwchar_unlocked (),
+.BR \%fgetwc_unlocked (),
+.BR \%fputwc_unlocked (),
+.BR \%putwchar_unlocked (),
+.BR \%fgetws_unlocked (),
+.BR \%fputws_unlocked ():
+.nf
+    _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+Each of these functions has the same behavior as its counterpart
+without the "_unlocked" suffix, except that they do not use locking
+(they do not set locks themselves, and do not test for the presence
+of locks set by others) and hence are thread-unsafe.
+See
+.BR flockfile (3).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR getc_unlocked (),
+.BR putc_unlocked (),
+.BR clearerr_unlocked (),
+.BR fflush_unlocked (),
+.BR fgetc_unlocked (),
+.BR fputc_unlocked (),
+.BR fread_unlocked (),
+.BR fwrite_unlocked (),
+.BR fgets_unlocked (),
+.BR fputs_unlocked (),
+.BR getwc_unlocked (),
+.BR fgetwc_unlocked (),
+.BR fputwc_unlocked (),
+.BR putwc_unlocked (),
+.BR fgetws_unlocked (),
+.BR fputws_unlocked ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Safe race:stream
+T}
+T{
+.na
+.nh
+.BR getchar_unlocked (),
+.BR getwchar_unlocked ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:stdin
+T}
+T{
+.na
+.nh
+.BR putchar_unlocked (),
+.BR putwchar_unlocked ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:stdout
+T}
+T{
+.na
+.nh
+.BR feof_unlocked (),
+.BR ferror_unlocked (),
+.BR fileno_unlocked ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR getc_unlocked ()
+.TQ
+.BR getchar_unlocked ()
+.TQ
+.BR putc_unlocked ()
+.TQ
+.BR putchar_unlocked ()
+POSIX.1-2008.
+.TP
+Others:
+None.
+.SH HISTORY
+.TP
+.BR getc_unlocked ()
+.TQ
+.BR getchar_unlocked ()
+.TQ
+.BR putc_unlocked ()
+.TQ
+.BR putchar_unlocked ()
+POSIX.1-2001.
+.\" E.g., in HP-UX 10.0. In HP-UX 10.30 they are called obsolescent, and
+.\" moved to a compatibility library.
+.\" Available in HP-UX 10.0: clearerr_unlocked, fclose_unlocked,
+.\" feof_unlocked, ferror_unlocked, fflush_unlocked, fgets_unlocked,
+.\" fgetwc_unlocked, fgetws_unlocked, fileno_unlocked, fputs_unlocked,
+.\" fputwc_unlocked, fputws_unlocked, fread_unlocked, fseek_unlocked,
+.\" ftell_unlocked, fwrite_unlocked, getc_unlocked, getchar_unlocked,
+.\" getw_unlocked, getwc_unlocked, getwchar_unlocked, putc_unlocked,
+.\" putchar_unlocked, puts_unlocked, putws_unlocked, putw_unlocked,
+.\" putwc_unlocked, putwchar_unlocked, rewind_unlocked, setvbuf_unlocked,
+.\" ungetc_unlocked, ungetwc_unlocked.
+.SH SEE ALSO
+.BR flockfile (3),
+.BR stdio (3)
diff --git a/man/man3/unlockpt.3 b/man/man3/unlockpt.3
new file mode 100644
index 000000000..cb8f18015
--- /dev/null
+++ b/man/man3/unlockpt.3
@@ -0,0 +1,84 @@
+'\" t
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This page is in the public domain. - aeb
+.\" %%%LICENSE_END
+.\"
+.TH unlockpt 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+unlockpt \- unlock a pseudoterminal master/slave pair
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #define _XOPEN_SOURCE
+.B #include <stdlib.h>
+.P
+.BI "int unlockpt(int " fd );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR unlockpt ():
+.nf
+    Since glibc 2.24:
+        _XOPEN_SOURCE >= 500
+.\"        || (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
+    glibc 2.23 and earlier:
+        _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR unlockpt ()
+function unlocks the slave pseudoterminal device
+corresponding to the master pseudoterminal referred to by the file descriptor
+.IR fd .
+.P
+.BR unlockpt ()
+should be called before opening the slave side of a pseudoterminal.
+.SH RETURN VALUE
+When successful,
+.BR unlockpt ()
+returns 0.
+Otherwise, it returns \-1 and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+The
+.I fd
+argument is not a file descriptor open for writing.
+.TP
+.B EINVAL
+The
+.I fd
+argument is not associated with a master pseudoterminal.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR unlockpt ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+POSIX.1-2001.
+.SH SEE ALSO
+.BR grantpt (3),
+.BR posix_openpt (3),
+.BR ptsname (3),
+.BR pts (4),
+.BR pty (7)
diff --git a/man/man3/unsetenv.3 b/man/man3/unsetenv.3
new file mode 100644
index 000000000..19ec56c24
--- /dev/null
+++ b/man/man3/unsetenv.3
@@ -0,0 +1 @@
+.so man3/setenv.3
diff --git a/man/man3/updwtmp.3 b/man/man3/updwtmp.3
new file mode 100644
index 000000000..b8e26be2c
--- /dev/null
+++ b/man/man3/updwtmp.3
@@ -0,0 +1,81 @@
+'\" t
+.\" Copyright 1997 Nicolás Lichtmaier <nick@debian.org>
+.\" Created Wed Jul  2 23:27:34 ART 1997
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Added info on availability, aeb, 971207
+.\" Added -lutil remark, 030718
+.\" 2008-07-02, mtk, document updwtmpx()
+.\"
+.TH updwtmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+updwtmp, logwtmp \- append an entry to the wtmp file
+.SH LIBRARY
+System utilities library
+.RI ( libutil ", " \-lutil )
+.SH SYNOPSIS
+.nf
+.B #include <utmp.h>
+.P
+.BI "void updwtmp(const char *" wtmp_file ", const struct utmp *" ut );
+.BI "void logwtmp(const char *" line ", const char *" name \
+", const char *" host );
+.fi
+.SH DESCRIPTION
+.BR updwtmp ()
+appends the utmp structure
+.I ut
+to the wtmp file.
+.P
+.BR logwtmp ()
+constructs a utmp structure using
+.IR line ", " name ", " host ,
+current time, and current process ID.
+Then it calls
+.BR updwtmp ()
+to append the structure to the wtmp file.
+.SH FILES
+.TP
+.I /var/log/wtmp
+database of past user logins
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR updwtmp (),
+.BR logwtmp ()
+T}	Thread safety	MT-Unsafe sig:ALRM timer
+.TE
+.SH VERSIONS
+For consistency with the other "utmpx" functions (see
+.BR getutxent (3)),
+glibc provides (since glibc 2.1):
+.P
+.in +4n
+.EX
+.BR "#define _GNU_SOURCE          " "/* See feature_test_macros(7) */"
+.B #include <utmpx.h>
+.BI "void updwtmpx (const char *" wtmpx_file ", const struct utmpx *" utx );
+.EE
+.in
+.P
+This function performs the same task as
+.BR updwtmp (),
+but differs in that it takes a
+.I utmpx
+structure as its last argument.
+.SH STANDARDS
+None.
+.SH HISTORY
+Solaris, NetBSD.
+.SH SEE ALSO
+.BR getutxent (3),
+.BR wtmp (5)
diff --git a/man/man3/updwtmpx.3 b/man/man3/updwtmpx.3
new file mode 100644
index 000000000..0dc4dea39
--- /dev/null
+++ b/man/man3/updwtmpx.3
@@ -0,0 +1 @@
+.so man3/updwtmp.3
diff --git a/man/man3/uselocale.3 b/man/man3/uselocale.3
new file mode 100644
index 000000000..3e3df603c
--- /dev/null
+++ b/man/man3/uselocale.3
@@ -0,0 +1,102 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH uselocale 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+uselocale \- set/get the locale for the calling thread
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <locale.h>
+.P
+.BI "locale_t uselocale(locale_t " newloc );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR uselocale ():
+.nf
+    Since glibc 2.10:
+        _XOPEN_SOURCE >= 700
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR uselocale ()
+function sets the current locale for the calling thread,
+and returns the thread's previously current locale.
+After a successful call to
+.BR uselocale (),
+any calls by this thread to functions that depend on the locale
+will operate as though the locale has been set to
+.IR newloc .
+.P
+The
+.I newloc
+argument can have one of the following values:
+.TP
+A handle returned by a call to \fBnewlocale\fP(3) or \fBduplocale\fP(3)
+The calling thread's current locale is set to the specified locale.
+.TP
+The special locale object handle \fBLC_GLOBAL_LOCALE\fP
+The calling thread's current locale is set to the global locale determined by
+.BR setlocale (3).
+.TP
+.I "(locale_t) 0"
+The calling thread's current locale is left unchanged
+(and the current locale is returned as the function result).
+.SH RETURN VALUE
+On success,
+.BR uselocale ()
+returns the locale handle that was set by the previous call to
+.BR uselocale ()
+in this thread, or
+.B LC_GLOBAL_LOCALE
+if there was no such previous call.
+On error, it returns
+.IR "(locale_t)\ 0" ,
+and sets
+.I errno
+to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I newloc
+does not refer to a valid locale object.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.3.
+POSIX.1-2008.
+.SH NOTES
+Unlike
+.BR setlocale (3),
+.BR uselocale ()
+does not allow selective replacement of individual locale categories.
+To employ a locale that differs in only a few categories from the current
+locale, use calls to
+.BR duplocale (3)
+and
+.BR newlocale (3)
+to obtain a locale object equivalent to the current locale and
+modify the desired categories in that object.
+.SH EXAMPLES
+See
+.BR newlocale (3)
+and
+.BR duplocale (3).
+.SH SEE ALSO
+.BR locale (1),
+.BR duplocale (3),
+.BR freelocale (3),
+.BR newlocale (3),
+.BR setlocale (3),
+.BR locale (5),
+.BR locale (7)
diff --git a/man/man3/usleep.3 b/man/man3/usleep.3
new file mode 100644
index 000000000..c0715c207
--- /dev/null
+++ b/man/man3/usleep.3
@@ -0,0 +1,123 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2001-04-01 by aeb
+.\" Modified 2003-07-23 by aeb
+.\"
+.TH usleep 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+usleep \- suspend execution for microsecond intervals
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <unistd.h>"
+.P
+.BI "int usleep(useconds_t " usec );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR usleep ():
+.nf
+    Since glibc 2.12:
+        (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L)
+            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
+            || /* glibc <= 2.19: */ _BSD_SOURCE
+    Before glibc 2.12:
+        _BSD_SOURCE || _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+.fi
+.SH DESCRIPTION
+The
+.BR usleep ()
+function suspends execution of the calling thread for
+(at least) \fIusec\fP microseconds.
+The sleep may be lengthened slightly
+by any system activity or by the time spent processing the call or by the
+granularity of system timers.
+.SH RETURN VALUE
+The
+.BR usleep ()
+function returns 0 on success.
+On error, \-1 is returned, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B EINTR
+Interrupted by a signal; see
+.BR signal (7).
+.TP
+.B EINVAL
+\fIusec\fP is greater than or equal to 1000000.
+(On systems where that is considered an error.)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR usleep ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+None.
+.SH HISTORY
+4.3BSD, POSIX.1-2001.
+POSIX.1-2001 declares it obsolete, suggesting
+.BR nanosleep (2)
+instead.
+Removed in POSIX.1-2008.
+.P
+On the original BSD implementation,
+and before glibc 2.2.2, the return type of this function is
+.IR void .
+The POSIX version returns
+.IR int ,
+and this is also the prototype used since glibc 2.2.2.
+.P
+Only the
+.B EINVAL
+error return is documented by SUSv2 and POSIX.1-2001.
+.SH CAVEATS
+The interaction of this function with the
+.B SIGALRM
+signal, and with other timer functions such as
+.BR alarm (2),
+.BR sleep (3),
+.BR nanosleep (2),
+.BR setitimer (2),
+.BR timer_create (2),
+.BR timer_delete (2),
+.BR timer_getoverrun (2),
+.BR timer_gettime (2),
+.BR timer_settime (2),
+.BR ualarm (3)
+is unspecified.
+.SH SEE ALSO
+.BR alarm (2),
+.BR getitimer (2),
+.BR nanosleep (2),
+.BR select (2),
+.BR setitimer (2),
+.BR sleep (3),
+.BR ualarm (3),
+.BR useconds_t (3type),
+.BR time (7)
diff --git a/man/man3/utmpname.3 b/man/man3/utmpname.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/utmpname.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/utmpxname.3 b/man/man3/utmpxname.3
new file mode 100644
index 000000000..29c36b72a
--- /dev/null
+++ b/man/man3/utmpxname.3
@@ -0,0 +1 @@
+.so man3/getutent.3
diff --git a/man/man3/va_arg.3 b/man/man3/va_arg.3
new file mode 100644
index 000000000..c419248e8
--- /dev/null
+++ b/man/man3/va_arg.3
@@ -0,0 +1 @@
+.so man3/stdarg.3
diff --git a/man/man3/va_copy.3 b/man/man3/va_copy.3
new file mode 100644
index 000000000..c419248e8
--- /dev/null
+++ b/man/man3/va_copy.3
@@ -0,0 +1 @@
+.so man3/stdarg.3
diff --git a/man/man3/va_end.3 b/man/man3/va_end.3
new file mode 100644
index 000000000..c419248e8
--- /dev/null
+++ b/man/man3/va_end.3
@@ -0,0 +1 @@
+.so man3/stdarg.3
diff --git a/man/man3/va_start.3 b/man/man3/va_start.3
new file mode 100644
index 000000000..c419248e8
--- /dev/null
+++ b/man/man3/va_start.3
@@ -0,0 +1 @@
+.so man3/stdarg.3
diff --git a/man/man3/valloc.3 b/man/man3/valloc.3
new file mode 100644
index 000000000..791d4c801
--- /dev/null
+++ b/man/man3/valloc.3
@@ -0,0 +1 @@
+.so man3/posix_memalign.3
diff --git a/man/man3/vasprintf.3 b/man/man3/vasprintf.3
new file mode 100644
index 000000000..5a8753a9c
--- /dev/null
+++ b/man/man3/vasprintf.3
@@ -0,0 +1 @@
+.so man3/asprintf.3
diff --git a/man/man3/vdprintf.3 b/man/man3/vdprintf.3
new file mode 100644
index 000000000..fa36f35d8
--- /dev/null
+++ b/man/man3/vdprintf.3
@@ -0,0 +1 @@
+.so man3/dprintf.3
diff --git a/man/man3/verr.3 b/man/man3/verr.3
new file mode 100644
index 000000000..3ee2e497a
--- /dev/null
+++ b/man/man3/verr.3
@@ -0,0 +1 @@
+.so man3/err.3
diff --git a/man/man3/verrx.3 b/man/man3/verrx.3
new file mode 100644
index 000000000..3ee2e497a
--- /dev/null
+++ b/man/man3/verrx.3
@@ -0,0 +1 @@
+.so man3/err.3
diff --git a/man/man3/versionsort.3 b/man/man3/versionsort.3
new file mode 100644
index 000000000..7e757c7a0
--- /dev/null
+++ b/man/man3/versionsort.3
@@ -0,0 +1 @@
+.so man3/scandir.3
diff --git a/man/man3/vfprintf.3 b/man/man3/vfprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/vfprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/vfscanf.3 b/man/man3/vfscanf.3
new file mode 100644
index 000000000..9fd424bb2
--- /dev/null
+++ b/man/man3/vfscanf.3
@@ -0,0 +1 @@
+.so man3/scanf.3
diff --git a/man/man3/vfwprintf.3 b/man/man3/vfwprintf.3
new file mode 100644
index 000000000..56ec9685b
--- /dev/null
+++ b/man/man3/vfwprintf.3
@@ -0,0 +1 @@
+.so man3/wprintf.3
diff --git a/man/man3/vlimit.3 b/man/man3/vlimit.3
new file mode 100644
index 000000000..58a817be8
--- /dev/null
+++ b/man/man3/vlimit.3
@@ -0,0 +1,3 @@
+.so man2/getrlimit.2
+.\" No new programs should use vlimit(3).
+.\" getrlimit(2) briefly discusses vlimit(3), so point the user there.
diff --git a/man/man3/vprintf.3 b/man/man3/vprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/vprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/vscanf.3 b/man/man3/vscanf.3
new file mode 100644
index 000000000..9fd424bb2
--- /dev/null
+++ b/man/man3/vscanf.3
@@ -0,0 +1 @@
+.so man3/scanf.3
diff --git a/man/man3/vsnprintf.3 b/man/man3/vsnprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/vsnprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/vsprintf.3 b/man/man3/vsprintf.3
new file mode 100644
index 000000000..975530d90
--- /dev/null
+++ b/man/man3/vsprintf.3
@@ -0,0 +1 @@
+.so man3/printf.3
diff --git a/man/man3/vsscanf.3 b/man/man3/vsscanf.3
new file mode 100644
index 000000000..8f5ebc15e
--- /dev/null
+++ b/man/man3/vsscanf.3
@@ -0,0 +1 @@
+.so man3/sscanf.3
diff --git a/man/man3/vswprintf.3 b/man/man3/vswprintf.3
new file mode 100644
index 000000000..56ec9685b
--- /dev/null
+++ b/man/man3/vswprintf.3
@@ -0,0 +1 @@
+.so man3/wprintf.3
diff --git a/man/man3/vsyslog.3 b/man/man3/vsyslog.3
new file mode 100644
index 000000000..ec352b291
--- /dev/null
+++ b/man/man3/vsyslog.3
@@ -0,0 +1 @@
+.so man3/syslog.3
diff --git a/man/man3/vtimes.3 b/man/man3/vtimes.3
new file mode 100644
index 000000000..4097ab77b
--- /dev/null
+++ b/man/man3/vtimes.3
@@ -0,0 +1,3 @@
+.so man2/getrusage.2
+.\" No new programs should use vtimes(3).
+.\" getrusage(2) briefly discusses vtimes(3), so point the user there.
diff --git a/man/man3/vwarn.3 b/man/man3/vwarn.3
new file mode 100644
index 000000000..3ee2e497a
--- /dev/null
+++ b/man/man3/vwarn.3
@@ -0,0 +1 @@
+.so man3/err.3
diff --git a/man/man3/vwarnx.3 b/man/man3/vwarnx.3
new file mode 100644
index 000000000..3ee2e497a
--- /dev/null
+++ b/man/man3/vwarnx.3
@@ -0,0 +1 @@
+.so man3/err.3
diff --git a/man/man3/vwprintf.3 b/man/man3/vwprintf.3
new file mode 100644
index 000000000..56ec9685b
--- /dev/null
+++ b/man/man3/vwprintf.3
@@ -0,0 +1 @@
+.so man3/wprintf.3
diff --git a/man/man3/warn.3 b/man/man3/warn.3
new file mode 100644
index 000000000..3ee2e497a
--- /dev/null
+++ b/man/man3/warn.3
@@ -0,0 +1 @@
+.so man3/err.3
diff --git a/man/man3/warnx.3 b/man/man3/warnx.3
new file mode 100644
index 000000000..3ee2e497a
--- /dev/null
+++ b/man/man3/warnx.3
@@ -0,0 +1 @@
+.so man3/err.3
diff --git a/man/man3/wcpcpy.3 b/man/man3/wcpcpy.3
new file mode 100644
index 000000000..aa20c097a
--- /dev/null
+++ b/man/man3/wcpcpy.3
@@ -0,0 +1,79 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcpcpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcpcpy \- copy a wide-character string, returning a pointer to its end
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcpcpy(wchar_t *restrict " dest \
+", const wchar_t *restrict " src );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wcpcpy ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR wcpcpy ()
+function is the wide-character equivalent of the
+.BR stpcpy (3)
+function.
+It copies the wide-character string pointed to by
+.IR src ,
+including the terminating null wide character (L\[aq]\e0\[aq]),
+to the array pointed to by
+.IR dest .
+.P
+The strings may not overlap.
+.P
+The programmer must ensure that there
+is room for at least
+.I wcslen(src)+1
+wide characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wcpcpy ()
+returns a pointer to the end of the wide-character string
+.IR dest ,
+that is, a pointer to the terminating null wide character.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcpcpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH SEE ALSO
+.BR strcpy (3),
+.BR wcscpy (3)
diff --git a/man/man3/wcpncpy.3 b/man/man3/wcpncpy.3
new file mode 100644
index 000000000..9b7ae8ca1
--- /dev/null
+++ b/man/man3/wcpncpy.3
@@ -0,0 +1,106 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcpncpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcpncpy \- copy a fixed-size string of wide characters,
+returning a pointer to its end
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcpncpy(wchar_t " dest "[restrict ." n ],
+.BI "                 const wchar_t " src "[restrict ." n ],
+.BI "                 size_t " n );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wcpncpy ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR wcpncpy ()
+function is the wide-character equivalent
+of the
+.BR stpncpy (3)
+function.
+It copies at most
+.I n
+wide characters from the wide-character
+string pointed to by
+.IR src ,
+including the terminating null wide (L\[aq]\e0\[aq]),
+to the array pointed to by
+.IR dest .
+Exactly
+.I n
+wide characters are
+written at
+.IR dest .
+If the length
+.I wcslen(src)
+is smaller than
+.IR n ,
+the remaining wide characters in the array pointed to
+by
+.I dest
+are filled with L\[aq]\e0\[aq] characters.
+If the length
+.I wcslen(src)
+is greater than or equal
+to
+.IR n ,
+the string pointed to by
+.I dest
+will
+not be L\[aq]\e0\[aq] terminated.
+.P
+The strings may not overlap.
+.P
+The programmer must ensure that there is room for at least
+.I n
+wide
+characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wcpncpy ()
+returns a pointer to the last wide character written, that is,
+.IR dest + n \-1.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcpncpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH SEE ALSO
+.BR stpncpy (3),
+.BR wcsncpy (3)
diff --git a/man/man3/wcrtomb.3 b/man/man3/wcrtomb.3
new file mode 100644
index 000000000..d7673312f
--- /dev/null
+++ b/man/man3/wcrtomb.3
@@ -0,0 +1,144 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcrtomb 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcrtomb \- convert a wide character to a multibyte sequence
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t wcrtomb(char *restrict " s ", wchar_t " wc \
+", mbstate_t *restrict " ps );
+.fi
+.SH DESCRIPTION
+The main case for this function is when
+.I s
+is
+not NULL and
+.I wc
+is not a null wide character (L\[aq]\e0\[aq]).
+In this case, the
+.BR wcrtomb ()
+function
+converts the wide character
+.I wc
+to its multibyte representation and stores it
+at the beginning of the character
+array pointed to by
+.IR s .
+It updates the shift state
+.IR *ps ,
+and
+returns the length of said multibyte representation,
+that is, the number of bytes
+written at
+.IR s .
+.P
+A different case is when
+.I s
+is not NULL,
+but
+.I wc
+is a null wide character (L\[aq]\e0\[aq]).
+In this case, the
+.BR wcrtomb ()
+function stores at
+the character array pointed to by
+.I s
+the shift sequence needed to
+bring
+.I *ps
+back to the initial state,
+followed by a \[aq]\e0\[aq] byte.
+It updates the shift state
+.I *ps
+(i.e., brings
+it into the initial state),
+and returns the length of the shift sequence plus
+one, that is, the number of bytes written at
+.IR s .
+.P
+A third case is when
+.I s
+is NULL.
+In this case,
+.I wc
+is ignored,
+and the function effectively returns
+.P
+.in +4n
+.EX
+wcrtomb(buf, L\[aq]\e0\[aq], ps)
+.EE
+.in
+.P
+where
+.I buf
+is an internal anonymous buffer.
+.P
+In all of the above cases, if
+.I ps
+is NULL, a static anonymous
+state known only to the
+.BR wcrtomb ()
+function is used instead.
+.SH RETURN VALUE
+The
+.BR wcrtomb ()
+function returns the number of
+bytes that have been or would
+have been written to the byte array at
+.IR s .
+If
+.I wc
+can not be
+represented as a multibyte sequence (according to the current locale),
+.I (size_t)\ \-1
+is returned, and
+.I errno
+set to
+.BR EILSEQ .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcrtomb ()
+T}	Thread safety	MT-Unsafe race:wcrtomb/!ps
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wcrtomb ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+Passing NULL as
+.I ps
+is not multithread safe.
+.SH SEE ALSO
+.BR mbsinit (3),
+.BR wcsrtombs (3)
diff --git a/man/man3/wcscasecmp.3 b/man/man3/wcscasecmp.3
new file mode 100644
index 000000000..88d88b2a3
--- /dev/null
+++ b/man/man3/wcscasecmp.3
@@ -0,0 +1,99 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcscasecmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcscasecmp \- compare two wide-character strings, ignoring case
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int wcscasecmp(const wchar_t *" s1 ", const wchar_t *" s2 );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wcscasecmp ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR wcscasecmp ()
+function is the wide-character equivalent of the
+.BR strcasecmp (3)
+function.
+It compares the wide-character string pointed to
+by
+.I s1
+and the wide-character string pointed to by
+.IR s2 ,
+ignoring
+case differences
+.RB ( towupper (3),
+.BR towlower (3)).
+.SH RETURN VALUE
+The
+.BR wcscasecmp ()
+function returns zero if the wide-character strings at
+.I s1
+and
+.I s2
+are equal except for case distinctions.
+It returns a
+positive integer if
+.I s1
+is greater than
+.IR s2 ,
+ignoring case.
+It
+returns a negative integer if
+.I s1
+is smaller
+than
+.IR s2 ,
+ignoring case.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcscasecmp ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+.SH NOTES
+The behavior of
+.BR wcscasecmp ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR strcasecmp (3),
+.BR wcscmp (3)
diff --git a/man/man3/wcscat.3 b/man/man3/wcscat.3
new file mode 100644
index 000000000..1cdf97f9f
--- /dev/null
+++ b/man/man3/wcscat.3
@@ -0,0 +1,70 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcscat 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcscat \- concatenate two wide-character strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcscat(wchar_t *restrict " dest \
+", const wchar_t *restrict " src );
+.fi
+.SH DESCRIPTION
+The
+.BR wcscat ()
+function is the wide-character equivalent
+of the
+.BR strcat (3)
+function.
+It copies the wide-character string pointed to by
+.IR src ,
+including the terminating null wide character (L\[aq]\e0\[aq]),
+to the end of the wide-character string pointed to by
+.IR dest .
+.P
+The strings may not overlap.
+.P
+The programmer must ensure that there is room for at least
+.IR wcslen(dest) + wcslen(src) +1
+wide characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wcscat ()
+returns
+.IR dest .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcscat ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strcat (3),
+.BR wcpcpy (3),
+.BR wcscpy (3),
+.BR wcsncat (3)
diff --git a/man/man3/wcschr.3 b/man/man3/wcschr.3
new file mode 100644
index 000000000..d12199b0e
--- /dev/null
+++ b/man/man3/wcschr.3
@@ -0,0 +1,69 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcschr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcschr \- search a wide character in a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcschr(const wchar_t *" wcs ", wchar_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR wcschr ()
+function is the wide-character equivalent
+of the
+.BR strchr (3)
+function.
+It searches the first occurrence of
+.I wc
+in the wide-character
+string pointed to by
+.IR wcs .
+.SH RETURN VALUE
+The
+.BR wcschr ()
+function returns a pointer to the first occurrence of
+.I wc
+in the wide-character string pointed to by
+.IR wcs ,
+or NULL if
+.I wc
+does not occur in the string.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcschr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strchr (3),
+.BR wcspbrk (3),
+.BR wcsrchr (3),
+.BR wcsstr (3),
+.BR wmemchr (3)
diff --git a/man/man3/wcscmp.3 b/man/man3/wcscmp.3
new file mode 100644
index 000000000..529edfaeb
--- /dev/null
+++ b/man/man3/wcscmp.3
@@ -0,0 +1,79 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcscmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcscmp \- compare two wide-character strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int wcscmp(const wchar_t *" s1 ", const wchar_t *" s2 );
+.fi
+.SH DESCRIPTION
+The
+.BR wcscmp ()
+function is the wide-character equivalent
+of the
+.BR strcmp (3)
+function.
+It compares the wide-character string pointed to by
+.I s1
+and the
+wide-character string pointed to by
+.IR s2 .
+.SH RETURN VALUE
+The
+.BR wcscmp ()
+function returns zero if the wide-character strings at
+.I s1
+and
+.I s2
+are equal.
+It returns an integer greater than zero if
+at the first differing position
+.IR i ,
+the corresponding wide-character
+.I s1[i]
+is greater than
+.IR s2[i] .
+It returns an integer less than zero if
+at the first differing position
+.IR i ,
+the corresponding wide-character
+.I s1[i]
+is less than
+.IR s2[i] .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcscmp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strcmp (3),
+.BR wcscasecmp (3),
+.BR wmemcmp (3)
diff --git a/man/man3/wcscpy.3 b/man/man3/wcscpy.3
new file mode 100644
index 000000000..83573fb1b
--- /dev/null
+++ b/man/man3/wcscpy.3
@@ -0,0 +1,72 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcscpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcscpy \- copy a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcscpy(wchar_t *restrict " dest \
+", const wchar_t *restrict " src );
+.fi
+.SH DESCRIPTION
+The
+.BR wcscpy ()
+function is the wide-character equivalent
+of the
+.BR strcpy (3)
+function.
+It copies the wide-character string pointed to by
+.IR src ,
+including the terminating null wide character (L\[aq]\e0\[aq]),
+to the array pointed to by
+.IR dest .
+.P
+The strings may not overlap.
+.P
+The programmer must ensure that there is
+room for at least
+.I wcslen(src)+1
+wide characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wcscpy ()
+returns
+.IR dest .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcscpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strcpy (3),
+.BR wcpcpy (3),
+.BR wcscat (3),
+.BR wcsdup (3),
+.BR wmemcpy (3)
diff --git a/man/man3/wcscspn.3 b/man/man3/wcscspn.3
new file mode 100644
index 000000000..a54578278
--- /dev/null
+++ b/man/man3/wcscspn.3
@@ -0,0 +1,81 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcscspn 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcscspn \- search a wide-character string for any of a set of wide characters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t wcscspn(const wchar_t *" wcs ", const wchar_t *" reject );
+.fi
+.SH DESCRIPTION
+The
+.BR wcscspn ()
+function is the wide-character equivalent
+of the
+.BR strcspn (3)
+function.
+It determines the length of the longest initial segment of
+.I wcs
+which consists entirely of wide-characters not listed in
+.IR reject .
+In
+other words, it searches for the first occurrence in the wide-character
+string
+.I wcs
+of any of the characters in the wide-character string
+.IR reject .
+.SH RETURN VALUE
+The
+.BR wcscspn ()
+function returns the number of
+wide characters in the longest
+initial segment of
+.I wcs
+which consists entirely of wide-characters not
+listed in
+.IR reject .
+In other words, it returns the position of the first
+occurrence in the wide-character string
+.I wcs
+of any of the characters in
+the wide-character string
+.IR reject ,
+or
+.I wcslen(wcs)
+if there is none.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcscspn ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strcspn (3),
+.BR wcspbrk (3),
+.BR wcsspn (3)
diff --git a/man/man3/wcsdup.3 b/man/man3/wcsdup.3
new file mode 100644
index 000000000..28fb0516f
--- /dev/null
+++ b/man/man3/wcsdup.3
@@ -0,0 +1,83 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcsdup 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsdup \- duplicate a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcsdup(const wchar_t *" s );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wcsdup ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR wcsdup ()
+function is the wide-character equivalent
+of the
+.BR strdup (3)
+function.
+It allocates and returns a new wide-character string whose initial
+contents is a duplicate of the wide-character string pointed to by
+.IR s .
+.P
+Memory for the new wide-character string is
+obtained with
+.BR malloc (3),
+and should be freed with
+.BR free (3).
+.SH RETURN VALUE
+On success,
+.BR wcsdup ()
+returns a pointer to the new wide-character string.
+On error, it returns NULL, with
+.I errno
+set to indicate the error.
+.SH ERRORS
+.TP
+.B ENOMEM
+Insufficient memory available to allocate duplicate string.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsdup ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+libc5, glibc 2.0.
+.SH SEE ALSO
+.BR strdup (3),
+.BR wcscpy (3)
diff --git a/man/man3/wcslen.3 b/man/man3/wcslen.3
new file mode 100644
index 000000000..ee30e6b42
--- /dev/null
+++ b/man/man3/wcslen.3
@@ -0,0 +1,65 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcslen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcslen \- determine the length of a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t wcslen(const wchar_t *" s );
+.fi
+.SH DESCRIPTION
+The
+.BR wcslen ()
+function is the wide-character equivalent
+of the
+.BR strlen (3)
+function.
+It determines the length of the wide-character string pointed to
+by
+.IR s ,
+excluding the terminating null wide character (L\[aq]\e0\[aq]).
+.SH RETURN VALUE
+The
+.BR wcslen ()
+function returns the
+number of wide characters in
+.IR s .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcslen ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+In cases where the input buffer may not contain
+a terminating null wide character,
+.BR wcsnlen (3)
+should be used instead.
+.SH SEE ALSO
+.BR strlen (3)
diff --git a/man/man3/wcsncasecmp.3 b/man/man3/wcsncasecmp.3
new file mode 100644
index 000000000..dba58b747
--- /dev/null
+++ b/man/man3/wcsncasecmp.3
@@ -0,0 +1,105 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcsncasecmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsncasecmp \- compare two fixed-size wide-character strings, ignoring case
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int wcsncasecmp(const wchar_t " s1 [. n "], const wchar_t " s2 [. n "], s\
+ize_t " n );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wcsncasecmp ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR wcsncasecmp ()
+function is the wide-character equivalent of the
+.BR strncasecmp (3)
+function.
+It compares the wide-character string pointed to
+by
+.I s1
+and the wide-character string
+pointed to by
+.IR s2 ,
+but at most
+.I n
+wide characters from each string, ignoring case differences
+.RB ( towupper (3),
+.BR towlower (3)).
+.SH RETURN VALUE
+The
+.BR wcsncasecmp ()
+function returns zero
+if the wide-character strings at
+.I s1
+and
+.IR s2 ,
+truncated to at most length
+.IR n ,
+are equal except
+for case distinctions.
+It returns a positive integer if truncated
+.I s1
+is
+greater than truncated
+.IR s2 ,
+ignoring case.
+It returns a negative integer
+if truncated
+.I s1
+is smaller than truncated
+.IR s2 ,
+ignoring case.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsncasecmp ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+.SH NOTES
+The behavior of
+.BR wcsncasecmp ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR strncasecmp (3),
+.BR wcsncmp (3)
diff --git a/man/man3/wcsncat.3 b/man/man3/wcsncat.3
new file mode 100644
index 000000000..9b4fe52e6
--- /dev/null
+++ b/man/man3/wcsncat.3
@@ -0,0 +1,72 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcsncat 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsncat \- concatenate two wide-character strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcsncat(wchar_t " dest "[restrict ." n ],
+.BI "                 const wchar_t " src "[restrict ." n ],
+.BI "                 size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wcsncat ()
+function is the wide-character equivalent of the
+.BR strncat (3)
+function.
+It copies at most
+.I n
+wide characters from the wide-character
+string pointed to by
+.I src
+to the end of the wide-character string pointed
+to by
+.IR dest ,
+and adds a terminating null wide character (L\[aq]\e0\[aq]).
+.P
+The strings may not overlap.
+.P
+The programmer must ensure that there is room for at least
+.IR wcslen(dest) + n +1
+wide characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wcsncat ()
+returns
+.IR dest .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsncat ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strncat (3),
+.BR wcscat (3)
diff --git a/man/man3/wcsncmp.3 b/man/man3/wcsncmp.3
new file mode 100644
index 000000000..4792e8285
--- /dev/null
+++ b/man/man3/wcsncmp.3
@@ -0,0 +1,93 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcsncmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsncmp \- compare two fixed-size wide-character strings
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int wcsncmp(const wchar_t " s1 [. n "], const wchar_t " s2 [. n "], \
+size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wcsncmp ()
+function is the wide-character equivalent of the
+.BR strncmp (3)
+function.
+It compares the wide-character string pointed to by
+.I s1
+and the
+wide-character string pointed to by
+.IR s2 ,
+but at most
+.I n
+wide
+characters from each string.
+In each string, the comparison extends only up
+to the first occurrence of a null wide character (L\[aq]\e0\[aq]), if any.
+.SH RETURN VALUE
+The
+.BR wcsncmp ()
+function returns zero if the wide-character strings at
+.I s1
+and
+.IR s2 ,
+truncated to at most length
+.IR n ,
+are equal.
+It returns an integer greater than zero if at the first differing position
+.I i
+.RI ( i
+<
+.IR n ),
+the corresponding wide-character
+.I s1[i]
+is
+greater than
+.IR s2[i] .
+It returns an integer less than zero if at the first
+differing position
+.I i
+.RI ( i
+<
+.IR n ),
+the corresponding
+wide-character
+.I s1[i]
+is less than
+.IR s2[i] .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsncmp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strncmp (3),
+.BR wcsncasecmp (3)
diff --git a/man/man3/wcsncpy.3 b/man/man3/wcsncpy.3
new file mode 100644
index 000000000..a42f17270
--- /dev/null
+++ b/man/man3/wcsncpy.3
@@ -0,0 +1,89 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcsncpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsncpy \- copy a fixed-size string of wide characters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcsncpy(wchar_t " dest "[restrict ." n ],
+.BI "                 const wchar_t " src "[restrict ." n ],
+.BI "                 size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wcsncpy ()
+function is the wide-character equivalent of the
+.BR strncpy (3)
+function.
+It copies at most
+.I n
+wide characters from the wide-character
+string pointed to by
+.IR src ,
+including the terminating null wide character (L\[aq]\e0\[aq]),
+to the array pointed to by
+.IR dest .
+Exactly
+.I n
+wide characters are
+written at
+.IR dest .
+If the length \fIwcslen(src)\fP is smaller than
+.IR n ,
+the remaining wide characters in the array
+pointed to by
+.I dest
+are filled
+with null wide characters.
+If the length \fIwcslen(src)\fP is greater than or equal
+to
+.IR n ,
+the string pointed to by
+.I dest
+will not be terminated by a null wide character.
+.P
+The strings may not overlap.
+.P
+The programmer must ensure that there is room for at least
+.I n
+wide
+characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wcsncpy ()
+returns
+.IR dest .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsncpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strncpy (3)
diff --git a/man/man3/wcsnlen.3 b/man/man3/wcsnlen.3
new file mode 100644
index 000000000..cd7dd6642
--- /dev/null
+++ b/man/man3/wcsnlen.3
@@ -0,0 +1,91 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcsnlen 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsnlen \- determine the length of a fixed-size wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t wcsnlen(const wchar_t " s [. maxlen "], size_t " maxlen );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wcsnlen ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR wcsnlen ()
+function is the wide-character equivalent
+of the
+.BR strnlen (3)
+function.
+It returns the number of wide-characters in the string pointed to by
+.IR s ,
+not including the terminating null wide character (L\[aq]\e0\[aq]),
+but at most
+.I maxlen
+wide characters (note: this parameter is not a byte count).
+In doing this,
+.BR wcsnlen ()
+looks at only the first
+.I maxlen
+wide characters at
+.I s
+and never beyond
+.IR s[maxlen\-1] .
+.SH RETURN VALUE
+The
+.BR wcsnlen ()
+function returns
+.IR wcslen(s) ,
+if that is less than
+.IR maxlen ,
+or
+.I maxlen
+if there is no null wide character among the
+first
+.I maxlen
+wide characters pointed to by
+.IR s .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsnlen ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+glibc 2.1.
+.SH SEE ALSO
+.BR strnlen (3),
+.BR wcslen (3)
diff --git a/man/man3/wcsnrtombs.3 b/man/man3/wcsnrtombs.3
new file mode 100644
index 000000000..229cf59a3
--- /dev/null
+++ b/man/man3/wcsnrtombs.3
@@ -0,0 +1,189 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcsnrtombs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsnrtombs \- convert a wide-character string to a multibyte string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t wcsnrtombs(char " dest "[restrict ." len "], \
+const wchar_t **restrict " src ,
+.BI "                  size_t " nwc ", size_t " len ", \
+mbstate_t *restrict " ps );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wcsnrtombs ():
+.nf
+    Since glibc 2.10:
+        _POSIX_C_SOURCE >= 200809L
+    Before glibc 2.10:
+        _GNU_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR wcsnrtombs ()
+function is like the
+.BR wcsrtombs (3)
+function,
+except that the number of wide characters to be converted,
+starting at
+.IR *src ,
+is limited to
+.IR nwc .
+.P
+If
+.I dest
+is not NULL,
+the
+.BR wcsnrtombs ()
+function converts
+at most
+.I nwc
+wide characters from
+the wide-character string
+.I *src
+to a multibyte string starting at
+.IR dest .
+At most
+.I len
+bytes are written to
+.IR dest .
+The shift state
+.I *ps
+is updated.
+The conversion is effectively performed by repeatedly
+calling
+.IR "wcrtomb(dest, *src, ps)" ,
+as long as this call succeeds,
+and then incrementing
+.I dest
+by the
+number of bytes written and
+.I *src
+by one.
+The conversion can stop for three reasons:
+.IP \[bu] 3
+A wide character has been encountered that can not be represented as a
+multibyte sequence (according to the current locale).
+In this case,
+.I *src
+is left pointing to the invalid wide character,
+.I (size_t)\ \-1
+is returned,
+and
+.I errno
+is set to
+.BR EILSEQ .
+.IP \[bu]
+.I nwc
+wide characters have been
+converted without encountering a null wide character (L\[aq]\e0\[aq]),
+or the length limit forces a stop.
+In this case,
+.I *src
+is left pointing
+to the next wide character to be converted, and the number of bytes written
+to
+.I dest
+is returned.
+.IP \[bu]
+The wide-character string has been completely converted, including the
+terminating null wide character (which has the side effect of bringing back
+.I *ps
+to the initial state).
+In this case,
+.I *src
+is set to NULL, and the number
+of bytes written to
+.IR dest ,
+excluding the terminating null byte (\[aq]\e0\[aq]), is
+returned.
+.P
+If
+.I dest
+is NULL,
+.I len
+is ignored,
+and the conversion proceeds as above,
+except that the converted bytes are not written out to memory, and that
+no destination length limit exists.
+.P
+In both of the above cases,
+if
+.I ps
+is NULL, a static anonymous
+state known only to the
+.BR wcsnrtombs ()
+function is used instead.
+.P
+The programmer must ensure that there is room for at least
+.I len
+bytes
+at
+.IR dest .
+.SH RETURN VALUE
+The
+.BR wcsnrtombs ()
+function returns
+the number of bytes that make up the
+converted part of multibyte sequence,
+not including the terminating null byte.
+If a wide character was encountered which
+could not be converted,
+.I (size_t)\ \-1
+is returned, and
+.I errno
+set to
+.BR EILSEQ .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsnrtombs ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:wcsnrtombs/!ps
+T}
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH NOTES
+The behavior of
+.BR wcsnrtombs ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+Passing NULL as
+.I ps
+is not multithread safe.
+.SH SEE ALSO
+.BR iconv (3),
+.BR mbsinit (3),
+.BR wcsrtombs (3)
diff --git a/man/man3/wcspbrk.3 b/man/man3/wcspbrk.3
new file mode 100644
index 000000000..4da04896e
--- /dev/null
+++ b/man/man3/wcspbrk.3
@@ -0,0 +1,69 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcspbrk 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcspbrk \- search a wide-character string for any of a set of wide characters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcspbrk(const wchar_t *" wcs ", const wchar_t *" accept );
+.fi
+.SH DESCRIPTION
+The
+.BR wcspbrk ()
+function is the wide-character equivalent
+of the
+.BR strpbrk (3)
+function.
+It searches for the first occurrence in the wide-character
+string pointed to by
+.I wcs
+of any of the
+characters in the wide-character
+string pointed to by
+.IR accept .
+.SH RETURN VALUE
+The
+.BR wcspbrk ()
+function returns a pointer to the first occurrence in
+.I wcs
+of any of the characters listed in
+.IR accept .
+If
+.I wcs
+contains none of these characters, NULL is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcspbrk ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strpbrk (3),
+.BR wcschr (3),
+.BR wcscspn (3)
diff --git a/man/man3/wcsrchr.3 b/man/man3/wcsrchr.3
new file mode 100644
index 000000000..eb3779f8c
--- /dev/null
+++ b/man/man3/wcsrchr.3
@@ -0,0 +1,66 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcsrchr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsrchr \- search a wide character in a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcsrchr(const wchar_t *" wcs ", wchar_t " wc );
+.fi
+.SH DESCRIPTION
+The
+.BR wcsrchr ()
+function is the wide-character equivalent
+of the
+.BR strrchr (3)
+function.
+It searches the last occurrence of
+.I wc
+in the wide-character
+string pointed to by
+.IR wcs .
+.SH RETURN VALUE
+The
+.BR wcsrchr ()
+function returns a pointer to the last occurrence of
+.I wc
+in the wide-character string pointed to by
+.IR wcs ,
+or NULL if
+.I wc
+does not occur in the string.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsrchr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strrchr (3),
+.BR wcschr (3)
diff --git a/man/man3/wcsrtombs.3 b/man/man3/wcsrtombs.3
new file mode 100644
index 000000000..28067cbed
--- /dev/null
+++ b/man/man3/wcsrtombs.3
@@ -0,0 +1,164 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcsrtombs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsrtombs \- convert a wide-character string to a multibyte string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t wcsrtombs(char " dest "[restrict ." len "], \
+const wchar_t **restrict " src ,
+.BI "                 size_t " len ", mbstate_t *restrict " ps );
+.fi
+.SH DESCRIPTION
+If
+.I dest
+is not NULL,
+the
+.BR wcsrtombs ()
+function converts
+the wide-character string
+.I *src
+to a multibyte string starting at
+.IR dest .
+At most
+.I len
+bytes are written to
+.IR dest .
+The shift state
+.I *ps
+is updated.
+The conversion is effectively performed by repeatedly
+calling
+.IR "wcrtomb(dest, *src, ps)" ,
+as long as this call succeeds,
+and then incrementing
+.I dest
+by the
+number of bytes written and
+.I *src
+by one.
+The conversion can stop for three reasons:
+.IP \[bu] 3
+A wide character has been encountered that can not be represented as a
+multibyte sequence (according to the current locale).
+In this case,
+.I *src
+is left pointing to the invalid wide character,
+.I (size_t)\ \-1
+is returned,
+and
+.I errno
+is set to
+.BR EILSEQ .
+.IP \[bu]
+The length limit forces a stop.
+In this case,
+.I *src
+is left pointing
+to the next wide character to be converted,
+and the number of bytes written to
+.I dest
+is returned.
+.IP \[bu]
+The wide-character string has been completely converted, including the
+terminating null wide character (L\[aq]\e0\[aq]),
+which has the side effect of bringing back
+.I *ps
+to the initial state.
+In this case,
+.I *src
+is set to NULL, and the number
+of bytes written to
+.IR dest ,
+excluding the terminating null byte (\[aq]\e0\[aq]),
+is returned.
+.P
+If
+.I dest
+is NULL,
+.I len
+is ignored,
+and the conversion proceeds as above, except that the converted bytes
+are not written out to memory, and that
+no length limit exists.
+.P
+In both of the above cases,
+if
+.I ps
+is NULL, a static anonymous
+state known only to the
+.BR wcsrtombs ()
+function is used instead.
+.P
+The programmer must ensure that there is room for at least
+.I len
+bytes
+at
+.IR dest .
+.SH RETURN VALUE
+The
+.BR wcsrtombs ()
+function returns
+the number of bytes that make up the
+converted part of multibyte sequence,
+not including the terminating null byte.
+If a wide character was encountered
+which could not be converted,
+.I (size_t)\ \-1
+is returned, and
+.I errno
+set to
+.BR EILSEQ .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsrtombs ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:wcsrtombs/!ps
+T}
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wcsrtombs ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+Passing NULL as
+.I ps
+is not multithread safe.
+.SH SEE ALSO
+.BR iconv (3),
+.BR mbsinit (3),
+.BR wcrtomb (3),
+.BR wcsnrtombs (3),
+.BR wcstombs (3)
diff --git a/man/man3/wcsspn.3 b/man/man3/wcsspn.3
new file mode 100644
index 000000000..8929e216e
--- /dev/null
+++ b/man/man3/wcsspn.3
@@ -0,0 +1,78 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcsspn 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsspn \- get length of a prefix wide-character substring
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "size_t wcsspn(const wchar_t *" wcs ", const wchar_t *" accept );
+.fi
+.SH DESCRIPTION
+The
+.BR wcsspn ()
+function is the wide-character equivalent of the
+.BR strspn (3)
+function.
+It determines the length of the longest initial segment of
+.I wcs
+which consists entirely of wide-characters listed in
+.IR accept .
+In other
+words, it searches for the first occurrence in the wide-character string
+.I wcs
+of a wide-character not contained in the wide-character string
+.IR accept .
+.SH RETURN VALUE
+The
+.BR wcsspn ()
+function returns the number of
+wide characters in the longest
+initial segment of
+.I wcs
+which consists entirely of wide-characters listed
+in
+.IR accept .
+In other words, it returns the position of the first
+occurrence in the wide-character string
+.I wcs
+of a wide-character not
+contained in the wide-character string
+.IR accept ,
+or
+.I wcslen(wcs)
+if there is none.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsspn ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strspn (3),
+.BR wcscspn (3)
diff --git a/man/man3/wcsstr.3 b/man/man3/wcsstr.3
new file mode 100644
index 000000000..d9bde3669
--- /dev/null
+++ b/man/man3/wcsstr.3
@@ -0,0 +1,75 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcsstr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcsstr \- locate a substring in a wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcsstr(const wchar_t *" haystack ", const wchar_t *" needle );
+.fi
+.SH DESCRIPTION
+The
+.BR wcsstr ()
+function is the wide-character equivalent of the
+.BR strstr (3)
+function.
+It searches for the first occurrence of the wide-character string
+.I needle
+(without its terminating null wide character (L\[aq]\e0\[aq]))
+as a substring in the wide-character string
+.IR haystack .
+.SH RETURN VALUE
+The
+.BR wcsstr ()
+function returns a pointer to the first occurrence of
+.I needle
+in
+.IR haystack .
+It returns NULL if
+.I needle
+does not occur
+as a substring in
+.IR haystack .
+.P
+Note the special case:
+If
+.I needle
+is the empty wide-character string,
+the return value is always
+.I haystack
+itself.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcsstr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR strstr (3),
+.BR wcschr (3)
diff --git a/man/man3/wcstoimax.3 b/man/man3/wcstoimax.3
new file mode 100644
index 000000000..40a677108
--- /dev/null
+++ b/man/man3/wcstoimax.3
@@ -0,0 +1,58 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH wcstoimax 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcstoimax, wcstoumax \- convert wide-character string to integer
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stddef.h>
+.B #include <inttypes.h>
+.P
+.BI "intmax_t wcstoimax(const wchar_t *restrict " nptr ,
+.BI "                   wchar_t **restrict " endptr ", int " base );
+.BI "uintmax_t wcstoumax(const wchar_t *restrict " nptr ,
+.BI "                   wchar_t **restrict " endptr ", int " base );
+.fi
+.SH DESCRIPTION
+These functions are just like
+.BR wcstol (3)
+and
+.BR wcstoul (3),
+except that they return a value of type
+.I intmax_t
+and
+.IR uintmax_t ,
+respectively.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcstoimax (),
+.BR wcstoumax ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR imaxabs (3),
+.BR imaxdiv (3),
+.BR strtoimax (3),
+.BR strtoumax (3),
+.\" FIXME . the pages referred to by the following xrefs are not yet written
+.BR wcstol (3),
+.BR wcstoul (3)
diff --git a/man/man3/wcstok.3 b/man/man3/wcstok.3
new file mode 100644
index 000000000..2e5f82460
--- /dev/null
+++ b/man/man3/wcstok.3
@@ -0,0 +1,117 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcstok 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcstok \- split wide-character string into tokens
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wcstok(wchar_t *restrict " wcs \
+", const wchar_t *restrict " delim ,
+.BI "                wchar_t **restrict " ptr );
+.fi
+.SH DESCRIPTION
+The
+.BR wcstok ()
+function is the wide-character equivalent of the
+.BR strtok (3)
+function,
+with an added argument to make it multithread-safe.
+It can be used
+to split a wide-character string
+.I wcs
+into tokens, where a token is
+defined as a substring not containing any wide-characters from
+.IR delim .
+.P
+The search starts at
+.IR wcs ,
+if
+.I wcs
+is not NULL,
+or at
+.IR *ptr ,
+if
+.I wcs
+is NULL.
+First, any delimiter wide-characters are skipped, that is, the
+pointer is advanced beyond any wide-characters which occur in
+.IR delim .
+If the end of the wide-character string is now
+reached,
+.BR wcstok ()
+returns NULL, to indicate that no tokens
+were found, and stores an appropriate value in
+.IR *ptr ,
+so that subsequent calls to
+.BR wcstok ()
+will continue to return NULL.
+Otherwise, the
+.BR wcstok ()
+function recognizes the beginning of a token
+and returns a pointer to it, but before doing that, it zero-terminates the
+token by replacing the next wide-character which occurs in
+.I delim
+with
+a null wide character (L\[aq]\e0\[aq]),
+and it updates
+.I *ptr
+so that subsequent calls will
+continue searching after the end of recognized token.
+.SH RETURN VALUE
+The
+.BR wcstok ()
+function returns a pointer to the next token,
+or NULL if no further token was found.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcstok ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The original
+.I wcs
+wide-character string is destructively modified during
+the operation.
+.SH EXAMPLES
+The following code loops over the tokens contained in a wide-character string.
+.P
+.EX
+wchar_t *wcs = ...;
+wchar_t *token;
+wchar_t *state;
+for (token = wcstok(wcs, L" \et\en", &state);
+    token != NULL;
+    token = wcstok(NULL, L" \et\en", &state)) {
+    ...
+}
+.EE
+.SH SEE ALSO
+.BR strtok (3),
+.BR wcschr (3)
diff --git a/man/man3/wcstombs.3 b/man/man3/wcstombs.3
new file mode 100644
index 000000000..403dacb3e
--- /dev/null
+++ b/man/man3/wcstombs.3
@@ -0,0 +1,125 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wcstombs 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcstombs \- convert a wide-character string to a multibyte string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "size_t wcstombs(char " dest "[restrict ." n "], \
+const wchar_t *restrict " src ,
+.BI "                size_t " n );
+.fi
+.SH DESCRIPTION
+If
+.I dest
+is not NULL, the
+.BR wcstombs ()
+function converts
+the wide-character string
+.I src
+to a multibyte string starting at
+.IR dest .
+At most
+.I n
+bytes are written to
+.IR dest .
+The sequence of characters placed in
+.I dest
+begins in the initial shift state.
+The conversion can stop for three reasons:
+.IP \[bu] 3
+A wide character has been encountered that can not be represented as a
+multibyte sequence (according to the current locale).
+In this case,
+.I (size_t)\ \-1
+is returned.
+.IP \[bu]
+The length limit forces a stop.
+In this case, the number of bytes written to
+.I dest
+is returned, but the shift state at this point is lost.
+.IP \[bu]
+The wide-character string has been completely converted, including the
+terminating null wide character (L\[aq]\e0\[aq]).
+In this case, the conversion ends in the initial shift state.
+The number of bytes written to
+.IR dest ,
+excluding the terminating null byte (\[aq]\e0\[aq]), is returned.
+.P
+The programmer must ensure that there is room for at least
+.I n
+bytes
+at
+.IR dest .
+.P
+If
+.I dest
+is NULL,
+.I n
+is ignored, and the conversion proceeds as
+above, except that the converted bytes are not written out to memory,
+and no length limit exists.
+.P
+In order to avoid the case 2 above, the programmer should make sure
+.I n
+is greater than or equal to
+.IR "wcstombs(NULL,src,0)+1" .
+.SH RETURN VALUE
+The
+.BR wcstombs ()
+function returns the number of bytes that make up the
+converted part of a multibyte sequence,
+not including the terminating null byte.
+If a wide character was encountered which could not be
+converted,
+.I (size_t)\ \-1
+is returned.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcstombs ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+The function
+.BR wcsrtombs (3)
+provides a better interface to the same functionality.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wcstombs ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR mblen (3),
+.BR mbstowcs (3),
+.BR mbtowc (3),
+.BR wcsrtombs (3),
+.BR wctomb (3)
diff --git a/man/man3/wcstoumax.3 b/man/man3/wcstoumax.3
new file mode 100644
index 000000000..f3aa5d2a0
--- /dev/null
+++ b/man/man3/wcstoumax.3
@@ -0,0 +1 @@
+.so man3/wcstoimax.3
diff --git a/man/man3/wcswidth.3 b/man/man3/wcswidth.3
new file mode 100644
index 000000000..444410d2f
--- /dev/null
+++ b/man/man3/wcswidth.3
@@ -0,0 +1,73 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcswidth 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcswidth \- determine columns needed for a fixed-size wide-character string
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _XOPEN_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <wchar.h>
+.P
+.BI "int wcswidth(const wchar_t *" s ", size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wcswidth ()
+function returns the
+number of columns needed to represent
+the wide-character string pointed to by
+.IR s ,
+but at most
+.I n
+wide
+characters.
+If a nonprintable wide character occurs among these characters,
+\-1 is returned.
+.SH RETURN VALUE
+The
+.BR wcswidth ()
+function
+returns the number of column positions for the
+wide-character string
+.IR s ,
+truncated to at most length
+.IR n .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcswidth ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The behavior of
+.BR wcswidth ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR iswprint (3),
+.BR wcwidth (3)
diff --git a/man/man3/wctob.3 b/man/man3/wctob.3
new file mode 100644
index 000000000..5c3d1d008
--- /dev/null
+++ b/man/man3/wctob.3
@@ -0,0 +1,86 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wctob 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wctob \- try to represent a wide character as a single byte
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int wctob(wint_t " c );
+.fi
+.SH DESCRIPTION
+The
+.BR wctob ()
+function tests whether
+the multibyte representation of the
+wide character
+.IR c ,
+starting in the initial state, consists of a single
+byte.
+If so, it is returned as an
+.IR "unsigned char" .
+.P
+Never use this function.
+It cannot help you in writing internationalized
+programs.
+Internationalized programs must never distinguish single-byte and
+multibyte characters.
+.SH RETURN VALUE
+The
+.BR wctob ()
+function returns the single-byte representation of
+.IR c ,
+if it exists, or
+.B EOF
+otherwise.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wctob ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wctob ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+This function should never be used.
+Internationalized programs must never
+distinguish single-byte and multibyte characters.
+Use either
+.BR wctomb (3)
+or the thread-safe
+.BR wcrtomb (3)
+instead.
+.SH SEE ALSO
+.BR btowc (3),
+.BR wcrtomb (3),
+.BR wctomb (3)
diff --git a/man/man3/wctomb.3 b/man/man3/wctomb.3
new file mode 100644
index 000000000..e500bc989
--- /dev/null
+++ b/man/man3/wctomb.3
@@ -0,0 +1,119 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wctomb 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wctomb \- convert a wide character to a multibyte sequence
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BI "int wctomb(char *" s ", wchar_t " wc );
+.fi
+.SH DESCRIPTION
+If
+.I s
+is not NULL,
+the
+.BR wctomb ()
+function converts the wide character
+.I wc
+to its multibyte representation and stores it at the beginning of
+the character array pointed to by
+.IR s .
+It updates the shift state, which
+is stored in a static anonymous variable
+known only to the
+.BR wctomb ()
+function,
+and returns the length of said multibyte representation,
+that is, the number of
+bytes written at
+.IR s .
+.P
+The programmer must ensure that there is
+room for at least
+.B MB_CUR_MAX
+bytes at
+.IR s .
+.P
+If
+.I s
+is NULL, the
+.BR wctomb ()
+function
+.\" The Dinkumware doc and the Single UNIX specification say this, but
+.\" glibc doesn't implement this.
+resets the shift state, known only to this function,
+to the initial state, and
+returns nonzero if the encoding has nontrivial shift state,
+or zero if the encoding is stateless.
+.SH RETURN VALUE
+If
+.I s
+is not NULL, the
+.BR wctomb ()
+function
+returns the number of bytes
+that have been written to the byte array at
+.IR s .
+If
+.I wc
+can not be
+represented as a multibyte sequence (according
+to the current locale), \-1 is returned.
+.P
+If
+.I s
+is NULL, the
+.BR wctomb ()
+function returns nonzero if the
+encoding has nontrivial shift state, or zero if the encoding is stateless.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wctomb ()
+T}	Thread safety	MT-Unsafe race
+.TE
+.SH VERSIONS
+The function
+.BR wcrtomb (3)
+provides
+a better interface to the same functionality.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wctomb ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR MB_CUR_MAX (3),
+.BR mblen (3),
+.BR mbstowcs (3),
+.BR mbtowc (3),
+.BR wcrtomb (3),
+.BR wcstombs (3)
diff --git a/man/man3/wctrans.3 b/man/man3/wctrans.3
new file mode 100644
index 000000000..e82fca0d6
--- /dev/null
+++ b/man/man3/wctrans.3
@@ -0,0 +1,88 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wctrans 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wctrans \- wide-character translation mapping
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "wctrans_t wctrans(const char *" name );
+.fi
+.SH DESCRIPTION
+The
+.I wctrans_t
+type represents a mapping
+which can map a wide character to
+another wide character.
+Its nature is implementation-dependent, but the special
+value
+.I (wctrans_t)\ 0
+denotes an invalid mapping.
+Nonzero
+.I wctrans_t
+values can be passed to the
+.BR towctrans (3)
+function to actually perform
+the wide-character mapping.
+.P
+The
+.BR wctrans ()
+function returns a mapping, given by its name.
+The set of
+valid names depends on the
+.B LC_CTYPE
+category of the current locale, but the
+following names are valid in all locales.
+.P
+.nf
+    "tolower" \- realizes the \fBtolower\fP(3) mapping
+    "toupper" \- realizes the \fBtoupper\fP(3) mapping
+.fi
+.SH RETURN VALUE
+The
+.BR wctrans ()
+function returns a mapping descriptor if the
+.I name
+is valid.
+Otherwise, it returns
+.IR "(wctrans_t)\ 0" .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wctrans ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wctrans ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR towctrans (3)
diff --git a/man/man3/wctype.3 b/man/man3/wctype.3
new file mode 100644
index 000000000..5e21005c6
--- /dev/null
+++ b/man/man3/wctype.3
@@ -0,0 +1,100 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wctype 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wctype \- wide-character classification
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wctype.h>
+.P
+.BI "wctype_t wctype(const char *" name );
+.fi
+.SH DESCRIPTION
+The
+.I wctype_t
+type represents a property which a wide character may or
+may not have.
+In other words, it represents a class of wide characters.
+This type's nature is implementation-dependent, but the special value
+.I "(wctype_t) 0"
+denotes an invalid property.
+Nonzero
+.I wctype_t
+values
+can be passed to the
+.BR iswctype (3)
+function
+to actually test whether a given
+wide character has the property.
+.P
+The
+.BR wctype ()
+function returns a property, given by its name.
+The set of
+valid names depends on the
+.B LC_CTYPE
+category of the current locale, but the
+following names are valid in all locales.
+.P
+.nf
+    "alnum" \- realizes the \fBisalnum\fP(3) classification function
+    "alpha" \- realizes the \fBisalpha\fP(3) classification function
+    "blank" \- realizes the \fBisblank\fP(3) classification function
+    "cntrl" \- realizes the \fBiscntrl\fP(3) classification function
+    "digit" \- realizes the \fBisdigit\fP(3) classification function
+    "graph" \- realizes the \fBisgraph\fP(3) classification function
+    "lower" \- realizes the \fBislower\fP(3) classification function
+    "print" \- realizes the \fBisprint\fP(3) classification function
+    "punct" \- realizes the \fBispunct\fP(3) classification function
+    "space" \- realizes the \fBisspace\fP(3) classification function
+    "upper" \- realizes the \fBisupper\fP(3) classification function
+    "xdigit" \- realizes the \fBisxdigit\fP(3) classification function
+.fi
+.SH RETURN VALUE
+The
+.BR wctype ()
+function returns a property descriptor
+if the
+.I name
+is valid.
+Otherwise, it returns
+.IR "(wctype_t) 0" .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wctype ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wctype ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR iswctype (3)
diff --git a/man/man3/wcwidth.3 b/man/man3/wcwidth.3
new file mode 100644
index 000000000..65e9ced73
--- /dev/null
+++ b/man/man3/wcwidth.3
@@ -0,0 +1,77 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wcwidth 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wcwidth \- determine columns needed for a wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#define _XOPEN_SOURCE" "       /* See feature_test_macros(7) */"
+.B #include <wchar.h>
+.P
+.BI "int wcwidth(wchar_t " c );
+.fi
+.SH DESCRIPTION
+The
+.BR wcwidth ()
+function returns the number of columns
+needed to represent the wide character
+.IR c .
+If
+.I c
+is a printable wide character, the value
+is at least 0.
+If
+.I c
+is null wide character (L\[aq]\e0\[aq]), the value is 0.
+Otherwise, \-1 is returned.
+.SH RETURN VALUE
+The
+.BR wcwidth ()
+function returns the number of
+column positions for
+.IR c .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wcwidth ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Note that before glibc 2.2.5, glibc used the prototype
+.P
+.nf
+.BI "int wcwidth(wint_t " c );
+.fi
+.SH NOTES
+The behavior of
+.BR wcwidth ()
+depends on the
+.B LC_CTYPE
+category of the
+current locale.
+.SH SEE ALSO
+.BR iswprint (3),
+.BR wcswidth (3)
diff --git a/man/man3/wmemchr.3 b/man/man3/wmemchr.3
new file mode 100644
index 000000000..638d2f785
--- /dev/null
+++ b/man/man3/wmemchr.3
@@ -0,0 +1,70 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wmemchr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wmemchr \- search a wide character in a wide-character array
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wmemchr(const wchar_t " s [. n "], wchar_t " c ", size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wmemchr ()
+function is the wide-character equivalent of the
+.BR memchr (3)
+function.
+It searches the
+.I n
+wide characters starting at
+.I s
+for
+the first occurrence of the wide character
+.IR c .
+.SH RETURN VALUE
+The
+.BR wmemchr ()
+function returns a pointer to the first occurrence of
+.I c
+among the
+.I n
+wide characters starting at
+.IR s ,
+or NULL if
+.I c
+does
+not occur among these.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wmemchr ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR memchr (3),
+.BR wcschr (3)
diff --git a/man/man3/wmemcmp.3 b/man/man3/wmemcmp.3
new file mode 100644
index 000000000..549057c7a
--- /dev/null
+++ b/man/man3/wmemcmp.3
@@ -0,0 +1,90 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"
+.TH wmemcmp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wmemcmp \- compare two arrays of wide-characters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "int wmemcmp(const wchar_t " s1 [. n "], const wchar_t " s2 [. n "], \
+size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wmemcmp ()
+function is the wide-character equivalent of the
+.BR memcmp (3)
+function.
+It compares the
+.I n
+wide-characters starting at
+.I s1
+and the
+.I n
+wide-characters starting at
+.IR s2 .
+.SH RETURN VALUE
+The
+.BR wmemcmp ()
+function returns
+zero if the wide-character arrays of size
+.I n
+at
+.I s1
+and
+.I s2
+are equal.
+It returns an integer greater than
+zero if at the first differing position
+.I i
+.RI ( i " <"
+.IR n ),
+the
+corresponding wide-character
+.I s1[i]
+is greater than
+.IR s2[i] .
+It returns an integer less than zero if
+at the first differing position
+.I i
+.RI ( i
+<
+.IR n ),
+the corresponding
+wide-character
+.I s1[i]
+is less than
+.IR s2[i] .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wmemcmp ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR memcmp (3),
+.BR wcscmp (3)
diff --git a/man/man3/wmemcpy.3 b/man/man3/wmemcpy.3
new file mode 100644
index 000000000..d44332230
--- /dev/null
+++ b/man/man3/wmemcpy.3
@@ -0,0 +1,75 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wmemcpy 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wmemcpy \- copy an array of wide-characters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wmemcpy(wchar_t " dest "[restrict ." n ],
+.BI "                 const wchar_t " src "[restrict ." n ],
+.BI "                 size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wmemcpy ()
+function is the wide-character equivalent of the
+.BR memcpy (3)
+function.
+It copies
+.I n
+wide characters from the array starting at
+.I src
+to the array starting at
+.IR dest .
+.P
+The arrays may not overlap; use
+.BR wmemmove (3)
+to copy between overlapping
+arrays.
+.P
+The programmer must ensure that there is room for at least
+.I n
+wide
+characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wmemcpy ()
+returns
+.IR dest .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wmemcpy ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR memcpy (3),
+.BR wcscpy (3),
+.BR wmemmove (3),
+.BR wmempcpy (3)
diff --git a/man/man3/wmemmove.3 b/man/man3/wmemmove.3
new file mode 100644
index 000000000..b460e4206
--- /dev/null
+++ b/man/man3/wmemmove.3
@@ -0,0 +1,70 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wmemmove 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wmemmove \- copy an array of wide-characters
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wmemmove(wchar_t " dest [. n "], const wchar_t " src [. n "], \
+size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wmemmove ()
+function is the wide-character equivalent of the
+.BR memmove (3)
+function.
+It copies
+.I n
+wide characters from the array
+starting at
+.I src
+to the array starting at
+.IR dest .
+The arrays may
+overlap.
+.P
+The programmer must ensure that there is room for at least
+.I n
+wide
+characters at
+.IR dest .
+.SH RETURN VALUE
+.BR wmemmove ()
+returns
+.IR dest .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wmemmove ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR memmove (3),
+.BR wmemcpy (3)
diff --git a/man/man3/wmempcpy.3 b/man/man3/wmempcpy.3
new file mode 100644
index 000000000..26750cb64
--- /dev/null
+++ b/man/man3/wmempcpy.3
@@ -0,0 +1 @@
+.so man3/mempcpy.3
diff --git a/man/man3/wmemset.3 b/man/man3/wmemset.3
new file mode 100644
index 000000000..a4323bc7a
--- /dev/null
+++ b/man/man3/wmemset.3
@@ -0,0 +1,61 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wmemset 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wmemset \- fill an array of wide-characters with a constant wide character
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <wchar.h>
+.P
+.BI "wchar_t *wmemset(wchar_t " wcs [. n "], wchar_t " wc ", size_t " n );
+.fi
+.SH DESCRIPTION
+The
+.BR wmemset ()
+function is the wide-character equivalent of the
+.BR memset (3)
+function.
+It fills the array of
+.I n
+wide-characters starting at
+.I wcs
+with
+.I n
+copies of the wide character
+.IR wc .
+.SH RETURN VALUE
+.BR wmemset ()
+returns
+.IR wcs .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wmemset ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH SEE ALSO
+.BR memset (3)
diff --git a/man/man3/wordexp.3 b/man/man3/wordexp.3
new file mode 100644
index 000000000..94a2a393b
--- /dev/null
+++ b/man/man3/wordexp.3
@@ -0,0 +1,245 @@
+'\" t
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH wordexp 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wordexp, wordfree \- perform word expansion like a posix-shell
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <wordexp.h>"
+.P
+.BI "int wordexp(const char *restrict " s ", wordexp_t *restrict " p \
+", int " flags );
+.BI "void wordfree(wordexp_t *" p );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR wordexp (),
+.BR wordfree ():
+.nf
+    _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+The function
+.BR wordexp ()
+performs a shell-like expansion of the string
+.I s
+and returns the result in the structure pointed to by
+.IR p .
+The data type
+.I wordexp_t
+is a structure that at least has the fields
+.IR we_wordc ,
+.IR we_wordv ,
+and
+.IR we_offs .
+The field
+.I we_wordc
+is a
+.I size_t
+that gives the number of words in the expansion of
+.IR s .
+The field
+.I we_wordv
+is a
+.I "char\ **"
+that points to the array of words found.
+The field
+.I we_offs
+of type
+.I size_t
+is sometimes (depending on
+.IR flags ,
+see below) used to indicate the number of initial elements in the
+.I we_wordv
+array that should be filled with NULLs.
+.P
+The function
+.BR wordfree ()
+frees the allocated memory again.
+More precisely, it does not free
+its argument, but it frees the array
+.I we_wordv
+and the strings that points to.
+.SS The string argument
+Since the expansion is the same as the expansion by the shell (see
+.BR sh (1))
+of the parameters to a command, the string
+.I s
+must not contain characters that would be illegal in shell command
+parameters.
+In particular, there must not be any unescaped
+newline or |, &, ;, <, >, (, ), {, } characters
+outside a command substitution or parameter substitution context.
+.P
+If the argument
+.I s
+contains a word that starts with an unquoted comment character #,
+then it is unspecified whether that word and all following words
+are ignored, or the # is treated as a non-comment character.
+.SS The expansion
+The expansion done consists of the following stages:
+tilde expansion (replacing \[ti]user by user's home directory),
+variable substitution (replacing $FOO by the value of the environment
+variable FOO), command substitution (replacing $(command) or \`command\`
+by the output of command), arithmetic expansion, field splitting,
+wildcard expansion, quote removal.
+.P
+The result of expansion of special parameters
+($@, $*, $#, $?, $\-, $$, $!, $0) is unspecified.
+.P
+Field splitting is done using the environment variable $IFS.
+If it is not set, the field separators are space, tab, and newline.
+.SS The output array
+The array
+.I we_wordv
+contains the words found, followed by a NULL.
+.SS The flags argument
+The
+.I flag
+argument is a bitwise inclusive OR of the following values:
+.TP
+.B WRDE_APPEND
+Append the words found to the array resulting from a previous call.
+.TP
+.B WRDE_DOOFFS
+Insert
+.I we_offs
+initial NULLs in the array
+.IR we_wordv .
+(These are not counted in the returned
+.IR we_wordc .)
+.TP
+.B WRDE_NOCMD
+Don't do command substitution.
+.TP
+.B WRDE_REUSE
+The argument
+.I p
+resulted from a previous call to
+.BR wordexp (),
+and
+.BR wordfree ()
+was not called.
+Reuse the allocated storage.
+.TP
+.B WRDE_SHOWERR
+Normally during command substitution
+.I stderr
+is redirected to
+.IR /dev/null .
+This flag specifies that
+.I stderr
+is not to be redirected.
+.TP
+.B WRDE_UNDEF
+Consider it an error if an undefined shell variable is expanded.
+.SH RETURN VALUE
+On success,
+.BR wordexp ()
+returns 0.
+On failure,
+.BR wordexp ()
+returns one of the following nonzero values:
+.TP
+.B WRDE_BADCHAR
+Illegal occurrence of newline or one of |, &, ;, <, >, (, ), {, }.
+.TP
+.B WRDE_BADVAL
+An undefined shell variable was referenced, and the
+.B WRDE_UNDEF
+flag
+told us to consider this an error.
+.TP
+.B WRDE_CMDSUB
+Command substitution requested, but the
+.B WRDE_NOCMD
+flag told us to consider this an error.
+.TP
+.B WRDE_NOSPACE
+Out of memory.
+.TP
+.B WRDE_SYNTAX
+Shell syntax error, such as unbalanced parentheses or
+unmatched quotes.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lbx
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wordexp ()
+T}	Thread safety	T{
+.na
+.nh
+MT-Unsafe race:utent const:env
+env sig:ALRM timer locale
+T}
+T{
+.na
+.nh
+.BR wordfree ()
+T}	Thread safety	MT-Safe
+.TE
+.P
+In the above table,
+.I utent
+in
+.I race:utent
+signifies that if any of the functions
+.BR setutent (3),
+.BR getutent (3),
+or
+.BR endutent (3)
+are used in parallel in different threads of a program,
+then data races could occur.
+.BR wordexp ()
+calls those functions,
+so we use race:utent to remind users.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+glibc 2.1.
+.SH EXAMPLES
+The output of the following example program
+is approximately that of "ls [a-c]*.c".
+.P
+.\" SRC BEGIN (wordexp.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <wordexp.h>
+\&
+int
+main(void)
+{
+    wordexp_t p;
+    char **w;
+\&
+    wordexp("[a\-c]*.c", &p, 0);
+    w = p.we_wordv;
+    for (size_t i = 0; i < p.we_wordc; i++)
+        printf("%s\en", w[i]);
+    wordfree(&p);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR fnmatch (3),
+.BR glob (3)
diff --git a/man/man3/wordfree.3 b/man/man3/wordfree.3
new file mode 100644
index 000000000..f0035e0ba
--- /dev/null
+++ b/man/man3/wordfree.3
@@ -0,0 +1 @@
+.so man3/wordexp.3
diff --git a/man/man3/wprintf.3 b/man/man3/wprintf.3
new file mode 100644
index 000000000..d8ebe47fa
--- /dev/null
+++ b/man/man3/wprintf.3
@@ -0,0 +1,273 @@
+'\" t
+.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" References consulted:
+.\"   GNU glibc-2 source code and manual
+.\"   Dinkumware C library reference http://www.dinkumware.com/
+.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
+.\"   ISO/IEC 9899:1999
+.\"
+.TH wprintf 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wprintf, fwprintf, swprintf, vwprintf, vfwprintf, vswprintf \- formatted
+wide-character output conversion
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.B #include <wchar.h>
+.P
+.BI "int wprintf(const wchar_t *restrict " format ", ...);"
+.BI "int fwprintf(FILE *restrict " stream ,
+.BI "             const wchar_t *restrict " format ", ...);"
+.BI "int swprintf(wchar_t " wcs "[restrict ." maxlen "], size_t " maxlen ,
+.BI "             const wchar_t *restrict " format ", ...);"
+.P
+.BI "int vwprintf(const wchar_t *restrict " format ", va_list " args );
+.BI "int vfwprintf(FILE *restrict " stream ,
+.BI "             const wchar_t *restrict " format ", va_list " args );
+.BI "int vswprintf(wchar_t " wcs "[restrict ." maxlen "], size_t " maxlen ,
+.BI "             const wchar_t *restrict " format ", va_list " args );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+All functions shown above:
+.\" .BR wprintf (),
+.\" .BR fwprintf (),
+.\" .BR swprintf (),
+.\" .BR vwprintf (),
+.\" .BR vfwprintf (),
+.\" .BR vswprintf ():
+.nf
+    _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE
+        || _POSIX_C_SOURCE >= 200112L
+.fi
+.SH DESCRIPTION
+The
+.BR wprintf ()
+family of functions is
+the wide-character equivalent of the
+.BR printf (3)
+family of functions.
+It performs formatted output of wide
+characters.
+.P
+The
+.BR wprintf ()
+and
+.BR vwprintf ()
+functions
+perform wide-character output to
+.IR stdout .
+.I stdout
+must not be byte oriented; see
+.BR fwide (3)
+for more information.
+.P
+The
+.BR fwprintf ()
+and
+.BR vfwprintf ()
+functions
+perform wide-character output to
+.IR stream .
+.I stream
+must not be byte oriented; see
+.BR fwide (3)
+for more information.
+.P
+The
+.BR swprintf ()
+and
+.BR vswprintf ()
+functions
+perform wide-character output
+to an array of wide characters.
+The programmer must ensure that there is
+room for at least
+.I maxlen
+wide
+characters at
+.IR wcs .
+.P
+These functions are like
+the
+.BR printf (3),
+.BR vprintf (3),
+.BR fprintf (3),
+.BR vfprintf (3),
+.BR sprintf (3),
+.BR vsprintf (3)
+functions except for the
+following differences:
+.TP
+.B \[bu]
+The
+.I format
+string is a wide-character string.
+.TP
+.B \[bu]
+The output consists of wide characters, not bytes.
+.TP
+.B \[bu]
+.BR swprintf ()
+and
+.BR vswprintf ()
+take a
+.I maxlen
+argument,
+.BR sprintf (3)
+and
+.BR vsprintf (3)
+do not.
+.RB ( snprintf (3)
+and
+.BR vsnprintf (3)
+take a
+.I maxlen
+argument, but these functions do not return \-1 upon
+buffer overflow on Linux.)
+.P
+The treatment of the conversion characters
+.B c
+and
+.B s
+is different:
+.TP
+.B c
+If no
+.B l
+modifier is present, the
+.I int
+argument is converted to a wide character by a call to the
+.BR btowc (3)
+function, and the resulting wide character is written.
+If an
+.B l
+modifier is present, the
+.I wint_t
+(wide character) argument is written.
+.TP
+.B s
+If no
+.B l
+modifier is present: the
+.I "const\ char\ *"
+argument is expected to be a pointer to an array of character type
+(pointer to a string) containing a multibyte character sequence beginning
+in the initial shift state.
+Characters from the array are converted to
+wide characters (each by a call to the
+.BR mbrtowc (3)
+function with a conversion state starting in the initial state before
+the first byte).
+The resulting wide characters are written up to
+(but not including) the terminating null wide character (L\[aq]\e0\[aq]).
+If a precision is
+specified, no more wide characters than the number specified are written.
+Note that the precision determines the number of
+.I wide characters
+written, not the number of
+.I bytes
+or
+.IR "screen positions" .
+The array must contain a terminating null byte (\[aq]\e0\[aq]),
+unless a precision is given
+and it is so small that the number of converted wide characters reaches it
+before the end of the array is reached.
+If an
+.B l
+modifier is present: the
+.I "const\ wchar_t\ *"
+argument is expected to be a pointer to an array of wide characters.
+Wide characters from the array are written up to (but not including) a
+terminating null wide character.
+If a precision is specified, no more than
+the number specified are written.
+The array must contain a terminating null
+wide character, unless a precision is given and it is smaller than or equal
+to the number of wide characters in the array.
+.SH RETURN VALUE
+The functions return the number of wide characters written, excluding the
+terminating null wide character in
+case of the functions
+.BR swprintf ()
+and
+.BR vswprintf ().
+They return \-1 when an error occurs.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR wprintf (),
+.BR fwprintf (),
+.BR swprintf (),
+.BR vwprintf (),
+.BR vfwprintf (),
+.BR vswprintf ()
+T}	Thread safety	MT-Safe locale
+.TE
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C99.
+.SH NOTES
+The behavior of
+.BR wprintf ()
+et al. depends
+on the
+.B LC_CTYPE
+category of the
+current locale.
+.P
+If the
+.I format
+string contains non-ASCII wide characters, the program
+will work correctly only if the
+.B LC_CTYPE
+category of the current locale at
+run time is the same as the
+.B LC_CTYPE
+category of the current locale at
+compile time.
+This is because the
+.I wchar_t
+representation is platform- and locale-dependent.
+(The glibc represents
+wide characters using their Unicode (ISO/IEC 10646) code point, but other
+platforms don't do this.
+Also, the use of C99 universal character names
+of the form \eunnnn does not solve this problem.)
+Therefore, in
+internationalized programs, the
+.I format
+string should consist of ASCII
+wide characters only, or should be constructed at run time in an
+internationalized way (e.g., using
+.BR gettext (3)
+or
+.BR iconv (3),
+followed by
+.BR mbstowcs (3)).
+.SH SEE ALSO
+.BR fprintf (3),
+.BR fputwc (3),
+.BR fwide (3),
+.BR printf (3),
+.BR snprintf (3)
+.\" .BR wscanf (3)
diff --git a/man/man3/xcrypt.3 b/man/man3/xcrypt.3
new file mode 100644
index 000000000..7c9786dd3
--- /dev/null
+++ b/man/man3/xcrypt.3
@@ -0,0 +1,95 @@
+'\" t
+.\"  Copyright 2003 walter harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\"  this is the 3rd type of interface for cryptographic routines
+.\"  1. encrypt() expects a bit field
+.\"  2. cbc_crypt() byte values
+.\"  3. xencrypt() a hexstring
+.\"  to bad to be true :(
+.\"
+.TH XCRYPT 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+xencrypt, xdecrypt, passwd2des \- RFS password encryption
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B "#include <rpc/des_crypt.h>"
+.P
+.BI "void passwd2des(char " *passwd ", char *" key ");"
+.P
+.BI "int xencrypt(char *" secret ", char *" passwd ");"
+.BI "int xdecrypt(char *" secret ", char *" passwd ");"
+.fi
+.SH DESCRIPTION
+.BR WARNING :
+Do not use these functions in new code.
+They do not achieve any type of acceptable cryptographic security guarantees.
+.P
+The function
+.BR passwd2des ()
+takes a character string
+.I passwd
+of arbitrary length and fills a character array
+.I key
+of length 8.
+The array
+.I key
+is suitable for use as DES key.
+It has odd parity set in bit 0 of each byte.
+Both other functions described here use this function to turn their
+argument
+.I passwd
+into a DES key.
+.P
+The
+.BR xencrypt ()
+function takes the ASCII character string
+.I secret
+given in hex,
+.\" (over the alphabet 0123456789abcdefABCDEF),
+which must have a length that is a multiple of 16,
+encrypts it using the DES key derived from
+.I passwd
+by
+.BR passwd2des (),
+and outputs the result again in
+.I secret
+as a hex string
+.\" (over the alphabet 0123456789abcdef)
+of the same length.
+.P
+The
+.BR xdecrypt ()
+function performs the converse operation.
+.SH RETURN VALUE
+The functions
+.BR xencrypt ()
+and
+.BR xdecrypt ()
+return 1 on success and 0 on error.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR passwd2des (),
+.BR xencrypt (),
+.BR xdecrypt ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+These functions are available since glibc 2.1.
+.SH BUGS
+The prototypes are missing from the abovementioned include file.
+.SH SEE ALSO
+.BR cbc_crypt (3)
diff --git a/man/man3/xdecrypt.3 b/man/man3/xdecrypt.3
new file mode 100644
index 000000000..01b6ce65a
--- /dev/null
+++ b/man/man3/xdecrypt.3
@@ -0,0 +1 @@
+.so man3/xcrypt.3
diff --git a/man/man3/xdr.3 b/man/man3/xdr.3
new file mode 100644
index 000000000..c0ac7d352
--- /dev/null
+++ b/man/man3/xdr.3
@@ -0,0 +1,609 @@
+'\" t
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\"
+.\" %%%LICENSE_START(BSD_ONELINE_CDROM)
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\" %%%LICENSE_END
+.\"
+.\" @(#)xdr.3n	2.2 88/08/03 4.0 RPCSRC; from 1.16 88/03/14 SMI
+.\"
+.\" 2007-12-30, mtk, Convert function prototypes to modern C syntax
+.\"
+.TH xdr 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+xdr \- library routines for external data representation
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS AND DESCRIPTION
+These routines allow C programmers to describe
+arbitrary data structures in a machine-independent fashion.
+Data for remote procedure calls are transmitted using these
+routines.
+.P
+The prototypes below are declared in
+.I <rpc/xdr.h>
+and make use of the following types:
+.P
+.RS 4
+.EX
+.BI "typedef int " bool_t ;
+.P
+.BI "typedef bool_t (*" xdrproc_t ")(XDR *, void *,...);"
+.EE
+.RE
+.P
+For the declaration of the
+.I XDR
+type, see
+.IR <rpc/xdr.h> .
+.P
+.nf
+.BI "bool_t xdr_array(XDR *" xdrs ", char **" arrp ", unsigned int *" sizep ,
+.BI "                 unsigned int " maxsize ", unsigned int " elsize ,
+.BI "                 xdrproc_t " elproc );
+.fi
+.IP
+A filter primitive that translates between variable-length arrays
+and their corresponding external representations.
+The argument
+.I arrp
+is the address of the pointer to the array, while
+.I sizep
+is the address of the element count of the array;
+this element count cannot exceed
+.IR maxsize .
+The argument
+.I elsize
+is the
+.I sizeof
+each of the array's elements, and
+.I elproc
+is an XDR filter that translates between
+the array elements' C form, and their external
+representation.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_bool(XDR *" xdrs ", bool_t *" bp );
+.fi
+.IP
+A filter primitive that translates between booleans (C
+integers)
+and their external representations.
+When encoding data, this
+filter produces values of either one or zero.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_bytes(XDR *" xdrs ", char **" sp ", unsigned int *" sizep ,
+.BI "                 unsigned int " maxsize );
+.fi
+.IP
+A filter primitive that translates between counted byte
+strings and their external representations.
+The argument
+.I sp
+is the address of the string pointer.
+The length of the
+string is located at address
+.IR sizep ;
+strings cannot be longer than
+.IR maxsize .
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_char(XDR *" xdrs ", char *" cp );
+.fi
+.IP
+A filter primitive that translates between C characters
+and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+Note: encoded characters are not packed, and occupy 4 bytes each.
+For arrays of characters, it is worthwhile to
+consider
+.BR xdr_bytes (),
+.BR xdr_opaque (),
+or
+.BR xdr_string ().
+.P
+.nf
+.BI "void xdr_destroy(XDR *" xdrs );
+.fi
+.IP
+A macro that invokes the destroy routine associated with the XDR stream,
+.IR xdrs .
+Destruction usually involves freeing private data structures
+associated with the stream.
+Using
+.I xdrs
+after invoking
+.BR xdr_destroy ()
+is undefined.
+.P
+.nf
+.BI "bool_t xdr_double(XDR *" xdrs ", double *" dp );
+.fi
+.IP
+A filter primitive that translates between C
+.I double
+precision numbers and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_enum(XDR *" xdrs ", enum_t *" ep );
+.fi
+.IP
+A filter primitive that translates between C
+.IR enum s
+(actually integers) and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_float(XDR *" xdrs ", float *" fp );
+.fi
+.IP
+A filter primitive that translates between C
+.IR float s
+and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "void xdr_free(xdrproc_t " proc ", char *" objp );
+.fi
+.IP
+Generic freeing routine.
+The first argument is the XDR routine for the object being freed.
+The second argument is a pointer to the object itself.
+Note: the pointer passed to this routine is
+.I not
+freed, but what it points to
+.I is
+freed (recursively).
+.P
+.nf
+.BI "unsigned int xdr_getpos(XDR *" xdrs );
+.fi
+.IP
+A macro that invokes the get-position routine
+associated with the XDR stream,
+.IR xdrs .
+The routine returns an unsigned integer,
+which indicates the position of the XDR byte stream.
+A desirable feature of XDR
+streams is that simple arithmetic works with this number,
+although the XDR stream instances need not guarantee this.
+.P
+.nf
+.BI "long *xdr_inline(XDR *" xdrs ", int " len );
+.fi
+.IP
+A macro that invokes the inline routine associated with the XDR stream,
+.IR xdrs .
+The routine returns a pointer
+to a contiguous piece of the stream's buffer;
+.I len
+is the byte length of the desired buffer.
+Note: pointer is cast to
+.IR "long\ *" .
+.IP
+Warning:
+.BR xdr_inline ()
+may return NULL (0)
+if it cannot allocate a contiguous piece of a buffer.
+Therefore the behavior may vary among stream instances;
+it exists for the sake of efficiency.
+.P
+.nf
+.BI "bool_t xdr_int(XDR *" xdrs ", int *" ip );
+.fi
+.IP
+A filter primitive that translates between C integers
+and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_long(XDR *" xdrs ", long *" lp );
+.fi
+.IP
+A filter primitive that translates between C
+.I long
+integers and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "void xdrmem_create(XDR *" xdrs ", char *" addr ", unsigned int " size ,
+.BI "                   enum xdr_op " op );
+.fi
+.IP
+This routine initializes the XDR stream object pointed to by
+.IR xdrs .
+The stream's data is written to, or read from,
+a chunk of memory at location
+.I addr
+whose length is no more than
+.I size
+bytes long.
+The
+.I op
+determines the direction of the XDR stream (either
+.BR XDR_ENCODE ,
+.BR XDR_DECODE ,
+or
+.BR XDR_FREE ).
+.P
+.nf
+.BI "bool_t xdr_opaque(XDR *" xdrs ", char *" cp ", unsigned int " cnt );
+.fi
+.IP
+A filter primitive that translates between fixed size opaque data
+and its external representation.
+The argument
+.I cp
+is the address of the opaque object, and
+.I cnt
+is its size in bytes.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_pointer(XDR *" xdrs ", char **" objpp ,
+.BI "                   unsigned int " objsize ", xdrproc_t " xdrobj );
+.fi
+.IP
+Like
+.BR xdr_reference ()
+except that it serializes null pointers, whereas
+.BR xdr_reference ()
+does not.
+Thus,
+.BR xdr_pointer ()
+can represent
+recursive data structures, such as binary trees or
+linked lists.
+.P
+.nf
+.BI "void xdrrec_create(XDR *" xdrs ", unsigned int " sendsize ,
+.BI "                   unsigned int " recvsize ", char *" handle ,
+.BI "                   int (*" readit ")(char *, char *, int),"
+.BI "                   int (*" writeit ")(char *, char *, int));"
+.fi
+.IP
+This routine initializes the XDR stream object pointed to by
+.IR xdrs .
+The stream's data is written to a buffer of size
+.IR sendsize ;
+a value of zero indicates the system should use a suitable default.
+The stream's data is read from a buffer of size
+.IR recvsize ;
+it too can be set to a suitable default by passing a zero value.
+When a stream's output buffer is full,
+.I writeit
+is called.
+Similarly, when a stream's input buffer is empty,
+.I readit
+is called.
+The behavior of these two routines is similar to
+the system calls
+.BR read (2)
+and
+.BR write (2),
+except that
+.I handle
+is passed to the former routines as the first argument.
+Note: the XDR stream's
+.I op
+field must be set by the caller.
+.IP
+Warning: to read from an XDR stream created by this API,
+you'll need to call
+.BR xdrrec_skiprecord ()
+first before calling any other XDR APIs.
+This inserts additional bytes in the stream to provide
+record boundary information.
+Also, XDR streams created with different
+.B xdr*_create
+APIs are not compatible for the same reason.
+.P
+.nf
+.BI "bool_t xdrrec_endofrecord(XDR *" xdrs ", int " sendnow );
+.fi
+.IP
+This routine can be invoked only on streams created by
+.BR xdrrec_create ().
+The data in the output buffer is marked as a completed record,
+and the output buffer is optionally written out if
+.I sendnow
+is nonzero.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdrrec_eof(XDR *" xdrs );
+.fi
+.IP
+This routine can be invoked only on streams created by
+.BR xdrrec_create ().
+After consuming the rest of the current record in the stream,
+this routine returns one if the stream has no more input,
+zero otherwise.
+.P
+.nf
+.BI "bool_t xdrrec_skiprecord(XDR *" xdrs );
+.fi
+.IP
+This routine can be invoked only on
+streams created by
+.BR xdrrec_create ().
+It tells the XDR implementation that the rest of the current record
+in the stream's input buffer should be discarded.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_reference(XDR *" xdrs ", char **" pp ", unsigned int " size ,
+.BI "                     xdrproc_t " proc );
+.fi
+.IP
+A primitive that provides pointer chasing within structures.
+The argument
+.I pp
+is the address of the pointer;
+.I size
+is the
+.I sizeof
+the structure that
+.I *pp
+points to; and
+.I proc
+is an XDR procedure that filters the structure
+between its C form and its external representation.
+This routine returns one if it succeeds, zero otherwise.
+.IP
+Warning: this routine does not understand null pointers.
+Use
+.BR xdr_pointer ()
+instead.
+.P
+.nf
+.BI "xdr_setpos(XDR *" xdrs ", unsigned int " pos );
+.fi
+.IP
+A macro that invokes the set position routine associated with
+the XDR stream
+.IR xdrs .
+The argument
+.I pos
+is a position value obtained from
+.BR xdr_getpos ().
+This routine returns one if the XDR stream could be repositioned,
+and zero otherwise.
+.IP
+Warning: it is difficult to reposition some types of XDR
+streams, so this routine may fail with one
+type of stream and succeed with another.
+.P
+.nf
+.BI "bool_t xdr_short(XDR *" xdrs ", short *" sp );
+.fi
+.IP
+A filter primitive that translates between C
+.I short
+integers and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "void xdrstdio_create(XDR *" xdrs ", FILE *" file ", enum xdr_op " op );
+.fi
+.IP
+This routine initializes the XDR stream object pointed to by
+.IR xdrs .
+The XDR stream data is written to, or read from, the
+.I stdio
+stream
+.IR file .
+The argument
+.I op
+determines the direction of the XDR stream (either
+.BR XDR_ENCODE ,
+.BR XDR_DECODE ,
+or
+.BR XDR_FREE ).
+.IP
+Warning: the destroy routine associated with such XDR streams calls
+.BR fflush (3)
+on the
+.I file
+stream, but never
+.BR fclose (3).
+.P
+.nf
+.BI "bool_t xdr_string(XDR *" xdrs ", char **" sp ", unsigned int " maxsize );
+.fi
+.IP
+A filter primitive that translates between C strings and
+their corresponding external representations.
+Strings cannot be longer than
+.IR maxsize .
+Note:
+.I sp
+is the address of the string's pointer.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_u_char(XDR *" xdrs ", unsigned char *" ucp );
+.fi
+.IP
+A filter primitive that translates between
+.I unsigned
+C characters and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_u_int(XDR *" xdrs ", unsigned int *" up );
+.fi
+.IP
+A filter primitive that translates between C
+.I unsigned
+integers and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_u_long(XDR *" xdrs ", unsigned long *" ulp );
+.fi
+.IP
+A filter primitive that translates between C
+.I "unsigned long"
+integers and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_u_short(XDR *" xdrs ", unsigned short *" usp );
+.fi
+.IP
+A filter primitive that translates between C
+.I "unsigned short"
+integers and their external representations.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_union(XDR *" xdrs ", enum_t *" dscmp ", char *" unp ,
+.BI "                 const struct xdr_discrim *" choices ,
+.BI "                 xdrproc_t " defaultarm ");     /* may equal NULL */"
+.fi
+.IP
+A filter primitive that translates between a discriminated C
+.I union
+and its corresponding external representation.
+It first
+translates the discriminant of the union located at
+.IR dscmp .
+This discriminant is always an
+.IR enum_t .
+Next the union located at
+.I unp
+is translated.
+The argument
+.I choices
+is a pointer to an array of
+.BR xdr_discrim ()
+structures.
+Each structure contains an ordered pair of
+.RI [ value , proc ].
+If the union's discriminant is equal to the associated
+.IR value ,
+then the
+.I proc
+is called to translate the union.
+The end of the
+.BR xdr_discrim ()
+structure array is denoted by a routine of value NULL.
+If the discriminant is not found in the
+.I choices
+array, then the
+.I defaultarm
+procedure is called (if it is not NULL).
+Returns one if it succeeds, zero otherwise.
+.P
+.nf
+.BI "bool_t xdr_vector(XDR *" xdrs ", char *" arrp ", unsigned int " size ,
+.BI "                  unsigned int " elsize ", xdrproc_t " elproc );
+.fi
+.IP
+A filter primitive that translates between fixed-length arrays
+and their corresponding external representations.
+The argument
+.I arrp
+is the address of the pointer to the array, while
+.I size
+is the element count of the array.
+The argument
+.I elsize
+is the
+.I sizeof
+each of the array's elements, and
+.I elproc
+is an XDR filter that translates between
+the array elements' C form, and their external
+representation.
+This routine returns one if it succeeds, zero otherwise.
+.P
+.nf
+.B bool_t xdr_void(void);
+.fi
+.IP
+This routine always returns one.
+It may be passed to RPC routines that require a function argument,
+where nothing is to be done.
+.P
+.nf
+.BI "bool_t xdr_wrapstring(XDR *" xdrs ", char **" sp );
+.fi
+.IP
+A primitive that calls
+.B "xdr_string(xdrs, sp,MAXUN.UNSIGNED );"
+where
+.B MAXUN.UNSIGNED
+is the maximum value of an unsigned integer.
+.BR xdr_wrapstring ()
+is handy because the RPC package passes a maximum of two XDR
+routines as arguments, and
+.BR xdr_string (),
+one of the most frequently used primitives, requires three.
+Returns one if it succeeds, zero otherwise.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR xdr_array (),
+.BR xdr_bool (),
+.BR xdr_bytes (),
+.BR xdr_char (),
+.BR xdr_destroy (),
+.BR xdr_double (),
+.BR xdr_enum (),
+.BR xdr_float (),
+.BR xdr_free (),
+.BR xdr_getpos (),
+.BR xdr_inline (),
+.BR xdr_int (),
+.BR xdr_long (),
+.BR xdrmem_create (),
+.BR xdr_opaque (),
+.BR xdr_pointer (),
+.BR xdrrec_create (),
+.BR xdrrec_eof (),
+.BR xdrrec_endofrecord (),
+.BR xdrrec_skiprecord (),
+.BR xdr_reference (),
+.BR xdr_setpos (),
+.BR xdr_short (),
+.BR xdrstdio_create (),
+.BR xdr_string (),
+.BR xdr_u_char (),
+.BR xdr_u_int (),
+.BR xdr_u_long (),
+.BR xdr_u_short (),
+.BR xdr_union (),
+.BR xdr_vector (),
+.BR xdr_void (),
+.BR xdr_wrapstring ()
+T}	Thread safety	MT-Safe
+.TE
+.SH SEE ALSO
+.BR rpc (3)
+.P
+The following manuals:
+.RS
+eXternal Data Representation Standard: Protocol Specification
+.br
+eXternal Data Representation: Sun Technical Notes
+.br
+.IR "XDR: External Data Representation Standard" ,
+RFC\ 1014, Sun Microsystems, Inc.,
+USC-ISI.
+.RE
diff --git a/man/man3/xdr_accepted_reply.3 b/man/man3/xdr_accepted_reply.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_accepted_reply.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_array.3 b/man/man3/xdr_array.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_array.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_authunix_parms.3 b/man/man3/xdr_authunix_parms.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_authunix_parms.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_bool.3 b/man/man3/xdr_bool.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_bool.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_bytes.3 b/man/man3/xdr_bytes.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_bytes.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_callhdr.3 b/man/man3/xdr_callhdr.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_callhdr.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_callmsg.3 b/man/man3/xdr_callmsg.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_callmsg.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_char.3 b/man/man3/xdr_char.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_char.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_destroy.3 b/man/man3/xdr_destroy.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_destroy.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_double.3 b/man/man3/xdr_double.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_double.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_enum.3 b/man/man3/xdr_enum.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_enum.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_float.3 b/man/man3/xdr_float.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_float.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_free.3 b/man/man3/xdr_free.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_free.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_getpos.3 b/man/man3/xdr_getpos.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_getpos.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_inline.3 b/man/man3/xdr_inline.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_inline.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_int.3 b/man/man3/xdr_int.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_int.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_long.3 b/man/man3/xdr_long.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_long.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_opaque.3 b/man/man3/xdr_opaque.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_opaque.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_opaque_auth.3 b/man/man3/xdr_opaque_auth.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_opaque_auth.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_pmap.3 b/man/man3/xdr_pmap.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_pmap.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_pmaplist.3 b/man/man3/xdr_pmaplist.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_pmaplist.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_pointer.3 b/man/man3/xdr_pointer.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_pointer.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_reference.3 b/man/man3/xdr_reference.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_reference.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_rejected_reply.3 b/man/man3/xdr_rejected_reply.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_rejected_reply.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_replymsg.3 b/man/man3/xdr_replymsg.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xdr_replymsg.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xdr_setpos.3 b/man/man3/xdr_setpos.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_setpos.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_short.3 b/man/man3/xdr_short.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_short.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_string.3 b/man/man3/xdr_string.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_string.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_u_char.3 b/man/man3/xdr_u_char.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_u_char.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_u_int.3 b/man/man3/xdr_u_int.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_u_int.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_u_long.3 b/man/man3/xdr_u_long.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_u_long.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_u_short.3 b/man/man3/xdr_u_short.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_u_short.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_union.3 b/man/man3/xdr_union.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_union.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_vector.3 b/man/man3/xdr_vector.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_vector.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_void.3 b/man/man3/xdr_void.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_void.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdr_wrapstring.3 b/man/man3/xdr_wrapstring.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdr_wrapstring.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdrmem_create.3 b/man/man3/xdrmem_create.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdrmem_create.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdrrec_create.3 b/man/man3/xdrrec_create.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdrrec_create.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdrrec_endofrecord.3 b/man/man3/xdrrec_endofrecord.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdrrec_endofrecord.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdrrec_eof.3 b/man/man3/xdrrec_eof.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdrrec_eof.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdrrec_skiprecord.3 b/man/man3/xdrrec_skiprecord.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdrrec_skiprecord.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xdrstdio_create.3 b/man/man3/xdrstdio_create.3
new file mode 100644
index 000000000..7ff092d05
--- /dev/null
+++ b/man/man3/xdrstdio_create.3
@@ -0,0 +1 @@
+.so man3/xdr.3
diff --git a/man/man3/xencrypt.3 b/man/man3/xencrypt.3
new file mode 100644
index 000000000..01b6ce65a
--- /dev/null
+++ b/man/man3/xencrypt.3
@@ -0,0 +1 @@
+.so man3/xcrypt.3
diff --git a/man/man3/xprt_register.3 b/man/man3/xprt_register.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xprt_register.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/xprt_unregister.3 b/man/man3/xprt_unregister.3
new file mode 100644
index 000000000..b18471167
--- /dev/null
+++ b/man/man3/xprt_unregister.3
@@ -0,0 +1 @@
+.so man3/rpc.3
diff --git a/man/man3/y0.3 b/man/man3/y0.3
new file mode 100644
index 000000000..783471291
--- /dev/null
+++ b/man/man3/y0.3
@@ -0,0 +1,276 @@
+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\"     Linux libc source code
+.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\"     386BSD man pages
+.\" Modified Sat Jul 24 19:08:17 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2002-08-25, aeb
+.\" Modified 2004-11-12 as per suggestion by Fabian Kreutz/AEB
+.\" 2008-07-24, mtk, created this page, based on material from j0.3.
+.\"
+.TH y0 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+y0, y0f, y0l, y1, y1f, y1l, yn, ynf, ynl \-
+Bessel functions of the second kind
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BI "double y0(double " x );
+.BI "double y1(double " x );
+.BI "double yn(int " n ", double " x );
+.P
+.BI "float y0f(float " x );
+.BI "float y1f(float " x );
+.BI "float ynf(int " n ", float " x );
+.P
+.BI "long double y0l(long double " x );
+.BI "long double y1l(long double " x );
+.BI "long double ynl(int " n ", long double " x );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR y0 (),
+.BR y1 (),
+.BR yn ():
+.nf
+    _XOPEN_SOURCE
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.P
+.BR y0f (),
+.BR y0l (),
+.BR y1f (),
+.BR y1l (),
+.BR ynf (),
+.BR ynl ():
+.nf
+    _XOPEN_SOURCE >= 600
+        || (_ISOC99_SOURCE && _XOPEN_SOURCE)
+        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
+        || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR y0 ()
+and
+.BR y1 ()
+functions return Bessel functions of
+.I x
+of the second kind of orders 0 and 1, respectively.
+The
+.BR yn ()
+function
+returns the Bessel function of
+.I x
+of the second kind of order
+.IR n .
+.P
+The value of
+.I x
+must be positive.
+.P
+The
+.BR y0f (),
+.BR y1f (),
+and
+.BR ynf ()
+functions are versions that take and return
+.I float
+values.
+The
+.BR y0l (),
+.BR y1l (),
+and
+.BR ynl ()
+functions are versions that take and return
+.I "long double"
+values.
+.SH RETURN VALUE
+On success, these functions return the appropriate
+Bessel value of the second kind for
+.IR x .
+.P
+If
+.I x
+is a NaN, a NaN is returned.
+.P
+If
+.I x
+is negative,
+a domain error occurs,
+and the functions return
+.RB \- HUGE_VAL ,
+.RB \- HUGE_VALF ,
+or
+.RB \- HUGE_VALL ,
+respectively.
+(POSIX.1-2001 also allows a NaN return for this case.)
+.P
+If
+.I x
+is 0.0,
+a pole error occurs,
+and the functions return
+.RB \- HUGE_VAL ,
+.RB \- HUGE_VALF ,
+or
+.RB \- HUGE_VALL ,
+respectively.
+.P
+If the result underflows,
+a range error occurs,
+and the functions return 0.0
+.P
+If the result overflows,
+a range error occurs,
+and the functions return
+.RB \- HUGE_VAL ,
+.RB \- HUGE_VALF ,
+or
+.RB \- HUGE_VALL ,
+respectively.
+(POSIX.1-2001 also allows a 0.0 return for this case.)
+.SH ERRORS
+See
+.BR math_error (7)
+for information on how to determine whether an error has occurred
+when calling these functions.
+.P
+The following errors can occur:
+.TP
+Domain error: \fIx\fP is negative
+.I errno
+is set to
+.BR EDOM .
+An invalid floating-point exception
+.RB ( FE_INVALID )
+is raised.
+.TP
+Pole error: \fIx\fP is 0.0
+.\" Before POSIX.1-2001 TC2, this was (inconsistently) specified
+.\" as a range error.
+.I errno
+is set to
+.B ERANGE
+and an
+.B FE_DIVBYZERO
+exception is raised
+(but see BUGS).
+.TP
+Range error: result underflow
+.\" e.g., y0(1e33) on glibc 2.8/x86-32
+.I errno
+is set to
+.BR ERANGE .
+No
+.B FE_UNDERFLOW
+exception is returned by
+.\" This is intended behavior
+.\" See https://www.sourceware.org/bugzilla/show_bug.cgi?id=6806
+.BR fetestexcept (3)
+for this case.
+.TP
+Range error: result overflow
+.\" e.g., yn(10, 1e-40) on glibc 2.8/x86-32
+.I errno
+is set to
+.B ERANGE
+(but see BUGS).
+An overflow floating-point exception
+.RB ( FE_OVERFLOW )
+is raised.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR y0 (),
+.BR y0f (),
+.BR y0l ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR y1 (),
+.BR y1f (),
+.BR y1l ()
+T}	Thread safety	MT-Safe
+T{
+.na
+.nh
+.BR yn (),
+.BR ynf (),
+.BR ynl ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+.TP
+.BR y0 ()
+.TQ
+.BR y1 ()
+.TQ
+.BR yn ()
+POSIX.1-2008.
+.TP
+Others:
+BSD.
+.SH HISTORY
+.TP
+.BR y0 ()
+.TQ
+.BR y1 ()
+.TQ
+.BR yn ()
+SVr4, 4.3BSD,
+POSIX.1-2001.
+.TP
+Others:
+BSD.
+.SH BUGS
+Before glibc 2.19,
+.\" http://sourceware.org/bugzilla/show_bug.cgi?id=6807
+these functions misdiagnosed pole errors:
+.I errno
+was set to
+.BR EDOM ,
+instead of
+.B ERANGE
+and no
+.B FE_DIVBYZERO
+exception was raised.
+.P
+Before glibc 2.17,
+.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6808
+did not set
+.I errno
+for "range error: result underflow".
+.P
+In glibc 2.3.2 and earlier,
+.\" Actually, 2.3.2 is the earliest test result I have; so yet
+.\" to confirm if this error occurs only in glibc 2.3.2.
+these functions do not raise an invalid floating-point exception
+.RB ( FE_INVALID )
+when a domain error occurs.
+.SH SEE ALSO
+.BR j0 (3)
diff --git a/man/man3/y0f.3 b/man/man3/y0f.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/y0f.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3/y0l.3 b/man/man3/y0l.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/y0l.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3/y1.3 b/man/man3/y1.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/y1.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3/y1f.3 b/man/man3/y1f.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/y1f.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3/y1l.3 b/man/man3/y1l.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/y1l.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3/yn.3 b/man/man3/yn.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/yn.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3/ynf.3 b/man/man3/ynf.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/ynf.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3/ynl.3 b/man/man3/ynl.3
new file mode 100644
index 000000000..88b3c9990
--- /dev/null
+++ b/man/man3/ynl.3
@@ -0,0 +1 @@
+.so man3/y0.3
diff --git a/man/man3const/EOF.3const b/man/man3const/EOF.3const
new file mode 100644
index 000000000..f41d1d15a
--- /dev/null
+++ b/man/man3const/EOF.3const
@@ -0,0 +1,42 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH EOF 3const (date) "Linux man-pages (unreleased)"
+.SH NAME
+EOF \- end of file or error indicator
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BR "#define EOF  " "/* ... */"
+.fi
+.SH DESCRIPTION
+.B EOF
+represents the end of an input file, or an error indication.
+It is a negative value, of type
+.IR int .
+.P
+.B EOF
+is not a character
+(it can't be represented by
+.IR "unsigned char" ).
+It is instead a sentinel value outside of the valid range for valid characters.
+.SH CONFORMING TO
+C99 and later;
+POSIX.1-2001 and later.
+.SH CAVEATS
+Programs can't pass this value to an output function
+to "write" the end of a file.
+That would likely result in undefined behavior.
+Instead,
+closing the writing stream or file descriptor
+that refers to such file
+is the way to signal the end of that file.
+.SH SEE ALSO
+.BR feof (3),
+.BR fgetc (3)
diff --git a/man/man3const/EXIT_FAILURE.3const b/man/man3const/EXIT_FAILURE.3const
new file mode 100644
index 000000000..ba0d62df9
--- /dev/null
+++ b/man/man3const/EXIT_FAILURE.3const
@@ -0,0 +1 @@
+.so man3const/EXIT_SUCCESS.3const
diff --git a/man/man3const/EXIT_SUCCESS.3const b/man/man3const/EXIT_SUCCESS.3const
new file mode 100644
index 000000000..260915eb8
--- /dev/null
+++ b/man/man3const/EXIT_SUCCESS.3const
@@ -0,0 +1,61 @@
+.\" Copyright (c) 2022 by Thomas Voss <mail@thomasvoss.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH EXIT_SUCCESS 3const (date) "Linux man-pages (unreleased)"
+.SH NAME
+EXIT_SUCCESS, EXIT_FAILURE \- termination status constants
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.P
+.BR "#define EXIT_SUCCESS  "  0
+.BR "#define EXIT_FAILURE  "  "/* nonzero */"
+.fi
+.SH DESCRIPTION
+.B EXIT_SUCCESS
+and
+.B EXIT_FAILURE
+represent a successful and unsuccessful exit status respectively,
+and can be used as arguments to the
+.BR exit (3)
+function.
+.SH CONFORMING TO
+C99 and later;
+POSIX.1-2001 and later.
+.SH EXAMPLES
+.\" SRC BEGIN (EXIT_SUCCESS.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+    FILE *fp;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <file>\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    fp = fopen(argv[1], "r");
+    if (fp == NULL) {
+        perror(argv[1]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Other code omitted */
+\&
+    fclose(fp);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR exit (3),
+.BR sysexits.h (3head)
diff --git a/man/man3const/NULL.3const b/man/man3const/NULL.3const
new file mode 100644
index 000000000..e395628a9
--- /dev/null
+++ b/man/man3const/NULL.3const
@@ -0,0 +1,74 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH NULL 3const (date) "Linux man-pages (unreleased)"
+.SH NAME
+NULL \- null pointer constant
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stddef.h>
+.P
+.B "#define NULL  ((void *) 0)"
+.fi
+.SH DESCRIPTION
+.B NULL
+represents a null pointer constant,
+that is, a pointer that does not point to anything.
+.SH CONFORMING TO
+C99 and later;
+POSIX.1-2001 and later.
+.SH NOTES
+The following headers also provide
+.BR NULL :
+.IR <locale.h> ,
+.IR <stdio.h> ,
+.IR <stdlib.h> ,
+.IR <string.h> ,
+.IR <time.h> ,
+.IR <unistd.h> ,
+and
+.IR <wchar.h> .
+.SH CAVEATS
+It is undefined behavior to dereference a null pointer,
+and that usually causes a segmentation fault in practice.
+.P
+It is also undefined behavior to perform pointer arithmetic on it.
+.P
+.I NULL \- NULL
+is undefined behavior, according to ISO C, but is defined to be 0 in C++.
+.P
+To avoid confusing human readers of the code,
+do not compare pointer variables to
+.BR 0 ,
+and do not assign
+.B 0
+to them.
+Instead, always use
+.BR NULL .
+.P
+.B NULL
+shouldn't be confused with
+.BR NUL ,
+which is an
+.BR ascii (7)
+character,
+represented in C as
+.BR \[aq]\e0\[aq] .
+.SH BUGS
+When it is necessary to set a pointer variable to a null pointer,
+it is not enough to use
+.BR memset (3)
+to zero the pointer
+(this is usually done when zeroing a struct that contains pointers),
+since ISO C and POSIX don't guarantee that a bit pattern of all 0s
+represent a null pointer.
+See the EXAMPLES section in
+.BR getaddrinfo (3)
+for an example program that does this correctly.
+.SH SEE ALSO
+.BR void (3type)
diff --git a/man/man3const/PA_CHAR.3const b/man/man3const/PA_CHAR.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_CHAR.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_DOUBLE.3const b/man/man3const/PA_DOUBLE.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_DOUBLE.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_FLAG_LONG.3const b/man/man3const/PA_FLAG_LONG.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_FLAG_LONG.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_FLAG_LONG_DOUBLE.3const b/man/man3const/PA_FLAG_LONG_DOUBLE.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_FLAG_LONG_DOUBLE.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_FLAG_LONG_LONG.3const b/man/man3const/PA_FLAG_LONG_LONG.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_FLAG_LONG_LONG.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_FLAG_PTR.3const b/man/man3const/PA_FLAG_PTR.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_FLAG_PTR.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_FLAG_SHORT.3const b/man/man3const/PA_FLAG_SHORT.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_FLAG_SHORT.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_FLOAT.3const b/man/man3const/PA_FLOAT.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_FLOAT.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_INT.3const b/man/man3const/PA_INT.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_INT.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_LAST.3const b/man/man3const/PA_LAST.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_LAST.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_POINTER.3const b/man/man3const/PA_POINTER.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_POINTER.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_STRING.3const b/man/man3const/PA_STRING.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_STRING.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_WCHAR.3const b/man/man3const/PA_WCHAR.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_WCHAR.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3const/PA_WSTRING.3const b/man/man3const/PA_WSTRING.3const
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3const/PA_WSTRING.3const
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3head/printf.h.3head b/man/man3head/printf.h.3head
new file mode 100644
index 000000000..42dceafe2
--- /dev/null
+++ b/man/man3head/printf.h.3head
@@ -0,0 +1,582 @@
+.\" Copyright (C) 2022 Alejandro Colomar <alx.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH printf.h 3head (date) "Linux man-pages (unreleased)"
+.SH NAME
+printf.h,
+\%register_printf_specifier,
+\%register_printf_modifier,
+\%register_printf_type,
+\%printf_function,
+\%printf_arginfo_size_function,
+\%printf_va_arg_function,
+\%printf_info,
+\%PA_INT,
+\%PA_CHAR,
+\%PA_WCHAR,
+\%PA_STRING,
+\%PA_WSTRING,
+\%PA_POINTER,
+\%PA_FLOAT,
+\%PA_DOUBLE,
+\%PA_LAST,
+\%PA_FLAG_LONG_LONG,
+\%PA_FLAG_LONG_DOUBLE,
+\%PA_FLAG_LONG,
+\%PA_FLAG_SHORT,
+\%PA_FLAG_PTR
+\- define custom behavior for printf-like functions
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <printf.h>
+.P
+.BI "int register_printf_specifier(int " spec ", printf_function " func ,
+.BI "                              printf_arginfo_size_function " arginfo );
+.BI "int register_printf_modifier(const wchar_t *" str );
+.BI "int register_printf_type(printf_va_arg_function " fct );
+.fi
+.SS Callbacks
+.nf
+.BI "typedef int printf_function(FILE *" stream ", const struct printf_info *" info ,
+.BI "                              const void *const " args []);
+.BI "typedef int printf_arginfo_size_function(const struct printf_info *" info ,
+.BI "                              size_t " n ", int " argtypes [ n "], int " size [ n ]);
+.BI "typedef void printf_va_arg_function(void *" mem ", va_list *" ap );
+.fi
+.SS Types
+.EX
+.B struct printf_info {
+.BR "    int            prec;            " "// Precision"
+.BR "    int            width;           " "// Width"
+.BR "    wchar_t        spec;            " "// Format letter"
+.BR "    unsigned int   is_long_double:1;" "// " L " or " ll " flag"
+.BR "    unsigned int   is_short:1;      " "// " h " flag"
+.BR "    unsigned int   is_long:1;       " "// " l " flag"
+.BR "    unsigned int   alt:1;           " "// " # " flag"
+.BR "    unsigned int   space:1;         " "// Space flag"
+.BR "    unsigned int   left:1;          " "// " - " flag"
+.BR "    unsigned int   showsign:1;      " "// " + " flag"
+.BR "    unsigned int   group:1;         " "// " \[aq] " flag"
+.BR "    unsigned int   extra:1;         " "// For special use"
+.BR "    unsigned int   is_char:1;       " "// " hh " flag"
+.BR "    unsigned int   wide:1;          " "// True for wide character streams"
+.BR "    unsigned int   i18n:1;          " "// " I " flag"
+.BR "    unsigned int   is_binary128:1;  " "/* Floating-point argument is"
+.BR "                                    " "   ABI-compatible with"
+.BR "                                    " "   IEC 60559 binary128 */"
+.BR "    unsigned short user;            " "// Bits for user-installed modifiers"
+.BR "    wchar_t        pad;             " "// Padding character"
+.B };
+.EE
+.SS Constants
+.EX
+.BR "#define PA_FLAG_LONG_LONG    " "/* ... */"
+.BR "#define PA_FLAG_LONG_DOUBLE  " "/* ... */"
+.BR "#define PA_FLAG_LONG         " "/* ... */"
+.BR "#define PA_FLAG_SHORT        " "/* ... */"
+.BR "#define PA_FLAG_PTR          " "/* ... */"
+.EE
+.SH DESCRIPTION
+These functions serve to extend and/or modify the behavior of the
+.BR printf (3)
+family of functions.
+.SS register_printf_specifier()
+This function registers a custom conversion specifier for the
+.BR printf (3)
+family of functions.
+.TP
+.I spec
+The character which will be used as a conversion specifier in the format string.
+.TP
+.I func
+Callback function that will be executed by the
+.BR printf (3)
+family of functions
+to format the input arguments into the output
+.IR stream .
+.RS
+.TP
+.I stream
+Output stream where the formatted output should be printed.
+This stream transparently represents the output,
+even in the case of functions that write to a string.
+.TP
+.I info
+Structure that holds context information,
+including the modifiers specified in the format string.
+This holds the same contents as in
+.IR arginfo .
+.TP
+.I args
+Array of pointers to the arguments to the
+.BR printf (3)\c
+-like function.
+.RE
+.TP
+.I arginfo
+Callback function that will be executed by the
+.BR printf (3)
+family of functions
+to know how many arguments should be parsed for the custom specifier
+and also their types.
+.RS
+.TP
+.I info
+Structure that holds context information,
+including the modifiers specified in the format string.
+This holds the same contents as in
+.IR func .
+.TP
+.I n
+Number of arguments remaining to be parsed.
+.TP
+.I argtypes
+This array should be set to
+define the type of each of the arguments that will be parsed.
+Each element in the array represents one of the arguments to be parsed,
+in the same order that they are passed to the
+.BR printf (3)\c
+-like function.
+Each element should be set to a base type
+.RB ( PA_ *)
+from the enum above,
+or a custom one,
+and optionally ORed with an appropriate length modifier
+.RB ( PA_FLAG_ *).
+.RS
+.P
+The type is determined by using one of the following constants:
+.TP
+.B PA_INT
+.IR int .
+.TP
+.B PA_CHAR
+.IR int ,
+cast to
+.IR char .
+.TP
+.B PA_WCHAR
+.IR wchar_t .
+.TP
+.B PA_STRING
+.IR "const char\~*" ,
+a \(aq\e0\(aq-terminated string.
+.TP
+.B PA_WSTRING
+.IR "const wchar_t\~*" ,
+a wide character L\(aq\e0\(aq-terminated string.
+.TP
+.B PA_POINTER
+.IR void\~* .
+.TP
+.B PA_FLOAT
+.IR float .
+.TP
+.B PA_DOUBLE
+.IR double .
+.TP
+.B PA_LAST
+TODO.
+.RE
+.TP
+.I size
+For user-defined types,
+the size of the type (in bytes) should also be specified through this array.
+Otherwise, leave it unused.
+.RE
+.P
+.I arginfo
+is called before
+.IR func ,
+and prepares some information needed to call
+.IR func .
+.SS register_printf_modifier()
+TODO
+.SS register_printf_type()
+TODO
+.SH RETURN VALUE
+.BR \%register_printf_specifier (),
+.BR \%register_printf_modifier (),
+and
+.BR \%register_printf_type ()
+return zero on success, or \-1 on error.
+.SS Callbacks
+The callback of type
+.I printf_function
+should return the number of characters written,
+or \-1 on error.
+.P
+The callback of type
+.I \%printf_arginfo_size_function
+should return the number of arguments to be parsed by this specifier.
+It also passes information about the type of those arguments
+to the caller through
+.IR argtypes .
+On error, it should return \-1.
+.SH ERRORS
+.TP
+.B EINVAL
+The specifier was not a valid character.
+.SH STANDARDS
+GNU.
+.SH HISTORY
+.BR \%register_printf_function (3)
+is an older function similar to
+.BR \%register_printf_specifier (),
+and is now deprecated.
+That function can't handle user-defined types.
+.P
+.BR \%register_printf_specifier ()
+supersedes
+.BR \%register_printf_function (3).
+.SH EXAMPLES
+The following example program registers the 'b' and 'B' specifiers
+to print integers in binary format,
+mirroring rules for other unsigned conversion specifiers like 'x' and 'u'.
+This can be used to print in binary prior to C23.
+.P
+.\" SRC BEGIN (register_printf_specifier.c)
+.EX
+/* This code is in the public domain */
+\&
+#include <err.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+\&
+#include <printf.h>
+\&
+#define GROUP_SEP  \[aq]\e\[aq]\[aq]
+\&
+struct Printf_Pad {
+    char    ch;
+    size_t  len;
+};
+\&
+static int b_printf(FILE *stream, const struct printf_info *info,
+                    const void *const args[]);
+static int b_arginf_sz(const struct printf_info *info,
+                    size_t n, int argtypes[n], int size[n]);
+\&
+static uintmax_t b_value(const struct printf_info *info,
+                    const void *arg);
+static size_t b_bin_repr(char bin[UINTMAX_WIDTH],
+                    const struct printf_info *info, const void *arg);
+static size_t b_bin_len(const struct printf_info *info,
+                    ptrdiff_t min_len);
+static size_t b_pad_len(const struct printf_info *info,
+                    ptrdiff_t bin_len);
+static ssize_t b_print_prefix(FILE *stream,
+                    const struct printf_info *info);
+static ssize_t b_pad_zeros(FILE *stream, const struct printf_info *info,
+                    ptrdiff_t min_len);
+static ssize_t b_print_number(FILE *stream,
+                    const struct printf_info *info,
+                    const char bin[UINTMAX_WIDTH],
+                    size_t min_len, size_t bin_len);
+static char pad_ch(const struct printf_info *info);
+static ssize_t pad_spaces(FILE *stream, size_t pad_len);
+\&
+int
+main(void)
+{
+    if (register_printf_specifier(\[aq]b\[aq], b_printf, b_arginf_sz) == \-1)
+        err(EXIT_FAILURE, "register_printf_specifier(\[aq]b\[aq], ...)");
+    if (register_printf_specifier(\[aq]B\[aq], b_printf, b_arginf_sz) == \-1)
+        err(EXIT_FAILURE, "register_printf_specifier(\[aq]B\[aq], ...)");
+\&
+    printf("....----....----....----....----\en");
+    printf("%llb;\en", 0x5Ellu);
+    printf("%lB;\en", 0x5Elu);
+    printf("%b;\en", 0x5Eu);
+    printf("%hB;\en", 0x5Eu);
+    printf("%hhb;\en", 0x5Eu);
+    printf("%jb;\en", (uintmax_t)0x5E);
+    printf("%zb;\en", (size_t)0x5E);
+    printf("....----....----....----....----\en");
+    printf("%#b;\en", 0x5Eu);
+    printf("%#B;\en", 0x5Eu);
+    printf("....----....----....----....----\en");
+    printf("%10b;\en", 0x5Eu);
+    printf("%010b;\en", 0x5Eu);
+    printf("%.10b;\en", 0x5Eu);
+    printf("....----....----....----....----\en");
+    printf("%\-10B;\en", 0x5Eu);
+    printf("....----....----....----....----\en");
+    printf("%\[aq]B;\en", 0x5Eu);
+    printf("....----....----....----....----\en");
+    printf("....----....----....----....----\en");
+    printf("%#16.12b;\en", 0xAB);
+    printf("%\-#\[aq]20.12b;\en", 0xAB);
+    printf("%#\[aq]020B;\en", 0xAB);
+    printf("....----....----....----....----\en");
+    printf("%#020B;\en", 0xAB);
+    printf("%\[aq]020B;\en", 0xAB);
+    printf("%020B;\en", 0xAB);
+    printf("....----....----....----....----\en");
+    printf("%#021B;\en", 0xAB);
+    printf("%\[aq]021B;\en", 0xAB);
+    printf("%021B;\en", 0xAB);
+    printf("....----....----....----....----\en");
+    printf("%#022B;\en", 0xAB);
+    printf("%\[aq]022B;\en", 0xAB);
+    printf("%022B;\en", 0xAB);
+    printf("....----....----....----....----\en");
+    printf("%#023B;\en", 0xAB);
+    printf("%\[aq]023B;\en", 0xAB);
+    printf("%023B;\en", 0xAB);
+    printf("....----....----....----....----\en");
+    printf("%\-#\[aq]19.11b;\en", 0xAB);
+    printf("%#\[aq]019B;\en", 0xAB);
+    printf("%#019B;\en", 0xAB);
+    printf("....----....----....----....----\en");
+    printf("%\[aq]019B;\en", 0xAB);
+    printf("%019B;\en", 0xAB);
+    printf("%#016b;\en", 0xAB);
+    printf("....----....----....----....----\en");
+\&
+    return 0;
+}
+\&
+static int
+b_printf(FILE *stream, const struct printf_info *info,
+         const void *const args[])
+{
+    char               bin[UINTMAX_WIDTH];
+    size_t             min_len, bin_len;
+    ssize_t            len, tmp;
+    struct Printf_Pad  pad = {0};
+\&
+    len = 0;
+\&
+    min_len = b_bin_repr(bin, info, args[0]);
+    bin_len = b_bin_len(info, min_len);
+\&
+    pad.ch = pad_ch(info);
+    if (pad.ch == \[aq] \[aq])
+        pad.len = b_pad_len(info, bin_len);
+\&
+    /* Padding with \[aq] \[aq] (right aligned) */
+    if ((pad.ch == \[aq] \[aq]) && !info->left) {
+        tmp = pad_spaces(stream, pad.len);
+        if (tmp == EOF)
+            return EOF;
+        len += tmp;
+    }
+\&
+    /* "0b"/"0B" prefix */
+    if (info->alt) {
+        tmp = b_print_prefix(stream, info);
+        if (tmp == EOF)
+            return EOF;
+        len += tmp;
+    }
+\&
+    /* Padding with \[aq]0\[aq] */
+    if (pad.ch == \[aq]0\[aq]) {
+        tmp = b_pad_zeros(stream, info, min_len);
+        if (tmp == EOF)
+            return EOF;
+        len += tmp;
+    }
+\&
+    /* Print number (including leading 0s to fill precision) */
+    tmp = b_print_number(stream, info, bin, min_len, bin_len);
+    if (tmp == EOF)
+        return EOF;
+    len += tmp;
+\&
+    /* Padding with \[aq] \[aq] (left aligned) */
+    if (info\->left) {
+        tmp = pad_spaces(stream, pad.len);
+        if (tmp == EOF)
+            return EOF;
+        len += tmp;
+    }
+\&
+    return len;
+}
+\&
+static int
+b_arginf_sz(const struct printf_info *info, size_t n, int argtypes[n],
+            [[maybe_unused]] int size[n])
+{
+    if (n < 1)
+        return \-1;
+\&
+    if (info\->is_long_double)
+        argtypes[0] = PA_INT | PA_FLAG_LONG_LONG;
+    else if (info\->is_long)
+        argtypes[0] = PA_INT | PA_FLAG_LONG;
+    else
+        argtypes[0] = PA_INT;
+\&
+    return 1;
+}
+\&
+static uintmax_t
+b_value(const struct printf_info *info, const void *arg)
+{
+    if (info\->is_long_double)
+        return *(const unsigned long long *)arg;
+    if (info\->is_long)
+        return *(const unsigned long *)arg;
+\&
+    /* short and char are both promoted to int */
+    return *(const unsigned int *)arg;
+}
+\&
+static size_t
+b_bin_repr(char bin[UINTMAX_WIDTH],
+           const struct printf_info *info, const void *arg)
+{
+    size_t     min_len;
+    uintmax_t  val;
+\&
+    val = b_value(info, arg);
+\&
+    bin[0] = \[aq]0\[aq];
+    for (min_len = 0; val; min_len++) {
+        bin[min_len] = \[aq]0\[aq] + (val % 2);
+        val >>= 1;
+    }
+\&
+    return MAX(min_len, 1);
+}
+\&
+static size_t
+b_bin_len(const struct printf_info *info, ptrdiff_t min_len)
+{
+    return MAX(info\->prec, min_len);
+}
+\&
+static size_t
+b_pad_len(const struct printf_info *info, ptrdiff_t bin_len)
+{
+    ptrdiff_t  pad_len;
+\&
+    pad_len = info\->width \- bin_len;
+    if (info\->alt)
+        pad_len \-= 2;
+    if (info\->group)
+        pad_len \-= (bin_len \- 1) / 4;
+\&
+    return MAX(pad_len, 0);
+}
+\&
+static ssize_t
+b_print_prefix(FILE *stream, const struct printf_info *info)
+{
+    ssize_t len;
+\&
+    len = 0;
+    if (fputc(\[aq]0\[aq], stream) == EOF)
+        return EOF;
+    len++;
+    if (fputc(info\->spec, stream) == EOF)
+        return EOF;
+    len++;
+\&
+    return len;
+}
+\&
+static ssize_t
+b_pad_zeros(FILE *stream, const struct printf_info *info,
+            ptrdiff_t min_len)
+{
+    ssize_t    len;
+    ptrdiff_t  tmp;
+\&
+    len = 0;
+    tmp = info\->width \- (info\->alt * 2);
+    if (info\->group)
+        tmp \-= tmp / 5 \- !(tmp % 5);
+    for (ptrdiff_t i = tmp \- 1; i > min_len \- 1; i\-\-) {
+        if (fputc(\[aq]0\[aq], stream) == EOF)
+            return EOF;
+        len++;
+\&
+        if (!info\->group || (i % 4))
+            continue;
+        if (fputc(GROUP_SEP, stream) == EOF)
+            return EOF;
+        len++;
+    }
+\&
+    return len;
+}
+\&
+static ssize_t
+b_print_number(FILE *stream, const struct printf_info *info,
+               const char bin[UINTMAX_WIDTH],
+               size_t min_len, size_t bin_len)
+{
+    ssize_t  len;
+\&
+    len = 0;
+\&
+    /* Print leading zeros to fill precision */
+    for (size_t i = bin_len \- 1; i > min_len \- 1; i\-\-) {
+        if (fputc(\[aq]0\[aq], stream) == EOF)
+            return EOF;
+        len++;
+\&
+        if (!info\->group || (i % 4))
+            continue;
+        if (fputc(GROUP_SEP, stream) == EOF)
+            return EOF;
+        len++;
+    }
+\&
+    /* Print number */
+    for (size_t i = min_len \- 1; i < min_len; i\-\-) {
+        if (fputc(bin[i], stream) == EOF)
+            return EOF;
+        len++;
+\&
+        if (!info\->group || (i % 4) || !i)
+            continue;
+        if (fputc(GROUP_SEP, stream) == EOF)
+            return EOF;
+        len++;
+    }
+\&
+    return len;
+}
+\&
+static char
+pad_ch(const struct printf_info *info)
+{
+    if ((info\->prec != \-1) || (info\->pad == \[aq] \[aq]) || info\->left)
+        return \[aq] \[aq];
+    return \[aq]0\[aq];
+}
+\&
+static ssize_t
+pad_spaces(FILE *stream, size_t pad_len)
+{
+    ssize_t  len;
+\&
+    len = 0;
+    for (size_t i = pad_len - 1; i < pad_len; i\-\-) {
+        if (fputc(\[aq] \[aq], stream) == EOF)
+            return EOF;
+        len++;
+    }
+\&
+    return len;
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR asprintf (3),
+.BR printf (3),
+.BR wprintf (3)
diff --git a/man/man3head/sysexits.h.3head b/man/man3head/sysexits.h.3head
new file mode 100644
index 000000000..01229d601
--- /dev/null
+++ b/man/man3head/sysexits.h.3head
@@ -0,0 +1,200 @@
+'\" t
+.\" Copyright (c) 1996 Joerg Wunsch
+.\" Copyright (c) 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.\" Rewritten for the Linux man-pages by Alejandro Colomar
+.\"
+.TH sysexits.h 3head (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysexits.h \- exit codes for programs
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sysexits.h>
+.fi
+.TS
+lB2 lB2 l1 lX.
+#define EX_OK	0	/*	T{
+successful termination */
+T}
+.P
+#define EX__BASE	64	/*	T{
+base value for error messages */
+T}
+.P
+#define EX_USAGE	64	/*	T{
+command line usage error */
+T}
+#define EX_DATAERR	65	/*	T{
+data format error */
+T}
+#define EX_NOINPUT	66	/*	T{
+cannot open input */
+T}
+#define EX_NOUSER	67	/*	T{
+addressee unknown */
+T}
+#define EX_NOHOST	68	/*	T{
+host name unknown */
+T}
+#define EX_UNAVAILABLE	69	/*	T{
+service unavailable */
+T}
+#define EX_SOFTWARE	70	/*	T{
+internal software error */
+T}
+#define EX_OSERR	71	/*	T{
+system error (e.g., can't fork) */
+T}
+#define EX_OSFILE	72	/*	T{
+critical OS file missing */
+T}
+#define EX_CANTCREAT	73	/*	T{
+can't create (user) output file */
+T}
+#define EX_IOERR	74	/*	T{
+input/output error */
+T}
+#define EX_TEMPFAIL	75	/*	T{
+temp failure; user is invited to retry */
+T}
+#define EX_PROTOCOL	76	/*	T{
+remote error in protocol */
+T}
+#define EX_NOPERM	77	/*	T{
+permission denied */
+T}
+#define EX_CONFIG	78	/*	T{
+configuration error */
+T}
+.P
+.T&
+lB2 l2 l1 lX.
+#define EX__MAX	...	/*	T{
+maximum listed value */
+T}
+.TE
+.SH DESCRIPTION
+A few programs exit with the following error codes.
+.P
+The successful exit is always indicated by a status of
+.BR 0 ,
+or
+.B EX_OK
+(equivalent to
+.B EXIT_SUCCESS
+from
+.IR <stdlib.h> ).
+Error numbers begin at
+.B EX__BASE
+to reduce the possibility of clashing with other exit statuses
+that random programs may already return.
+The meaning of the code is approximately as follows:
+.TP
+.B EX_USAGE
+The command was used incorrectly,
+e.g.,
+with the wrong number of arguments,
+a bad flag,
+bad syntax in a parameter,
+or whatever.
+.TP
+.B EX_DATAERR
+The input data was incorrect in some way.
+This should only be used for user's data and not system files.
+.TP
+.B EX_NOINPUT
+An input file (not a system file) did not exist or was not readable.
+This could also include errors like "No message" to a mailer
+(if it cared to catch it).
+.TP
+.B EX_NOUSER
+The user specified did not exist.
+This might be used for mail addresses or remote logins.
+.TP
+.B EX_NOHOST
+The host specified did not exist.
+This is used in mail addresses or network requests.
+.TP
+.B EX_UNAVAILABLE
+A service is unavailable.
+This can occur if a support program or file does not exist.
+This can also be used as a catch-all message
+when something you wanted to do doesn't work, but you don't know why.
+.TP
+.B EX_SOFTWARE
+An internal software error has been detected.
+This should be limited to non-operating system related errors if possible.
+.TP
+.B EX_OSERR
+An operating system error has been detected.
+This is intended to be used for such things as
+"cannot fork",
+"cannot create pipe",
+or the like.
+It includes things like
+.BR getuid (2)
+returning a user that does not exist in the
+.BR passwd (5)
+file.
+.TP
+.B EX_OSFILE
+Some system file
+(e.g.,
+.IR /etc/passwd ,
+.IR /etc/utmp ,
+etc.)
+does not exist,
+cannot be opened,
+or has some sort of error (e.g., syntax error).
+.TP
+.B EX_CANTCREAT
+A (user specified) output file cannot be created.
+.TP
+.B EX_IOERR
+An error occurred while doing I/O on some file.
+.TP
+.B EX_TEMPFAIL
+Temporary failure,
+indicating something that is not really an error.
+For example that a mailer could not create a connection,
+and the request should be reattempted later.
+.TP
+.B EX_PROTOCOL
+The remote system returned something that
+was "not possible" during a protocol exchange.
+.TP
+.B EX_OSFILE
+You did not have sufficient permission to perform the operation.
+This is not intended for file system problems,
+which should use
+.B EX_NOINPUT
+or
+.BR EX_CANTCREAT ,
+but rather for higher level permissions.
+.TP
+.B EX_CONFIG
+Something was found in an unconfigured or misconfigured state.
+.P
+The numerical values corresponding to the symbolical ones
+are given in parenthesis for easy reference.
+.SH STANDARDS
+BSD.
+.SH HISTORY
+The
+.I <sysexits.h>
+file appeared in 4.0BSD for use by the deliverymail utility,
+later renamed to
+.BR sendmail (8).
+.SH CAVEATS
+The choice of an appropriate exit value is often ambiguous.
+.SH SEE ALSO
+.BR err (3),
+.BR error (3),
+.BR exit (3)
diff --git a/man/man3type/FILE.3type b/man/man3type/FILE.3type
new file mode 100644
index 000000000..5c2dfd1a3
--- /dev/null
+++ b/man/man3type/FILE.3type
@@ -0,0 +1,36 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH FILE 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+FILE \- input/output stream
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdio.h>
+.P
+.BR typedef " /* ... */  " FILE;
+.fi
+.SH DESCRIPTION
+An object type used for streams.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH NOTES
+The following header also provides this type:
+.IR <wchar.h> .
+.SH SEE ALSO
+.BR fclose (3),
+.BR flockfile (3),
+.BR fopen (3),
+.BR fprintf (3),
+.BR fread (3),
+.BR fscanf (3),
+.BR stdin (3),
+.BR stdio (3)
diff --git a/man/man3type/aiocb.3type b/man/man3type/aiocb.3type
new file mode 100644
index 000000000..9e7190e68
--- /dev/null
+++ b/man/man3type/aiocb.3type
@@ -0,0 +1,42 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH aiocb 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+aiocb \- asynchronous I/O control block
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <aio.h>
+.P
+.B struct aiocb {
+.BR "    int             aio_fildes;" "     /* File descriptor */"
+.BR "    off_t           aio_offset;" "     /* File offset */"
+.BR "    volatile void  *aio_buf;" "        /* Location of buffer */"
+.BR "    size_t          aio_nbytes;" "     /* Length of transfer */"
+.BR "    int             aio_reqprio;" "    /* Request priority offset */"
+.BR "    struct sigevent aio_sigevent;" "   /* Signal number and value */"
+.BR "    int             aio_lio_opcode;" " /* Operation to be performed */"
+.B };
+.EE
+.SH DESCRIPTION
+For further information about this structure, see
+.BR aio (7).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_fsync (3),
+.BR aio_read (3),
+.BR aio_return (3),
+.BR aio_suspend (3),
+.BR aio_write (3),
+.BR lio_listio (3)
diff --git a/man/man3type/blkcnt_t.3type b/man/man3type/blkcnt_t.3type
new file mode 100644
index 000000000..32c20cc0e
--- /dev/null
+++ b/man/man3type/blkcnt_t.3type
@@ -0,0 +1,30 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH blkcnt_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+blkcnt_t \- file block counts
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */ " blkcnt_t;
+.fi
+.SH DESCRIPTION
+Used for file block counts.
+It is a signed integer type.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following header also provides this type:
+.IR <sys/stat.h> .
+.SH SEE ALSO
+.BR stat (3type)
diff --git a/man/man3type/blksize_t.3type b/man/man3type/blksize_t.3type
new file mode 100644
index 000000000..7384a38e1
--- /dev/null
+++ b/man/man3type/blksize_t.3type
@@ -0,0 +1,30 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH blksize_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+blksize_t \- file block sizes
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */ " blksize_t;
+.fi
+.SH DESCRIPTION
+Used for file block sizes.
+It is a signed integer type.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following header also provides this type:
+.IR <sys/stat.h> .
+.SH SEE ALSO
+.BR stat (3type)
diff --git a/man/man3type/cc_t.3type b/man/man3type/cc_t.3type
new file mode 100644
index 000000000..811233193
--- /dev/null
+++ b/man/man3type/cc_t.3type
@@ -0,0 +1,35 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH cc_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+cc_t, speed_t, tcflag_t \- terminal special characters, baud rates, modes
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <termios.h>
+.P
+.BR typedef " /* ... */ " cc_t;
+.BR typedef " /* ... */ " speed_t;
+.BR typedef " /* ... */ " tcflag_t;
+.fi
+.SH DESCRIPTION
+.I cc_t
+is used for terminal special characters,
+.I speed_t
+for baud rates, and
+.I tcflag_t
+for modes.
+.P
+All are unsigned integer types.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR termios (3)
diff --git a/man/man3type/clock_t.3type b/man/man3type/clock_t.3type
new file mode 100644
index 000000000..b6248a93d
--- /dev/null
+++ b/man/man3type/clock_t.3type
@@ -0,0 +1,37 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH clock_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+clock_t \- system time
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BR typedef " /* ... */ " clock_t;
+.fi
+.SH DESCRIPTION
+Used for system time in clock ticks or
+.B CLOCKS_PER_SEC
+(defined in
+.IR <time.h> ).
+According to POSIX,
+it is an integer type or a real-floating type.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH NOTES
+The following headers also provide this type:
+.I <sys/types.h>
+and
+.IR <sys/times.h> .
+.SH SEE ALSO
+.BR times (2),
+.BR clock (3)
diff --git a/man/man3type/clockid_t.3type b/man/man3type/clockid_t.3type
new file mode 100644
index 000000000..38d760f80
--- /dev/null
+++ b/man/man3type/clockid_t.3type
@@ -0,0 +1,28 @@
+.TH clockid_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+clockid_t \- clock ID for the clock and timer functions
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */ " clockid_t;
+.fi
+.SH DESCRIPTION
+Used for clock ID type in the clock and timer functions.
+It is defined as an arithmetic type.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following header also provides this type:
+.IR <time.h> .
+.SH SEE ALSO
+.BR clock_adjtime (2),
+.BR clock_getres (2),
+.BR clock_nanosleep (2),
+.BR timer_create (2),
+.BR clock_getcpuclockid (3)
diff --git a/man/man3type/dev_t.3type b/man/man3type/dev_t.3type
new file mode 100644
index 000000000..dd68f2603
--- /dev/null
+++ b/man/man3type/dev_t.3type
@@ -0,0 +1,33 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH dev_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+dev_t \- device ID
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */  " dev_t;
+.fi
+.SH DESCRIPTION
+Used for device IDs.
+It is an integer type.
+For further details of this type, see
+.BR makedev (3).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following header also provides this type:
+.IR <sys/stat.h> .
+.SH SEE ALSO
+.BR mknod (2),
+.BR stat (3type)
diff --git a/man/man3type/div_t.3type b/man/man3type/div_t.3type
new file mode 100644
index 000000000..7abbb7616
--- /dev/null
+++ b/man/man3type/div_t.3type
@@ -0,0 +1,59 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH div_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+div_t, ldiv_t, lldiv_t, imaxdiv_t \-
+quotient and remainder of an integer division
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <stdlib.h>
+.P
+.B typedef struct {
+.BR "    int quot;" " /* Quotient */"
+.BR "    int rem;" "  /* Remainder */"
+.B } div_t;
+.P
+.B typedef struct {
+.BR "    long quot;" " /* Quotient */"
+.BR "    long rem;" "  /* Remainder */"
+.B } ldiv_t;
+.P
+.B typedef struct {
+.BR "    long long quot;" " /* Quotient */"
+.BR "    long long rem;" "  /* Remainder */"
+.B } lldiv_t;
+.P
+.B #include <inttypes.h>
+.P
+.B typedef struct {
+.BR "    intmax_t quot;" " /* Quotient */"
+.BR "    intmax_t rem;" "  /* Remainder */"
+.B } imaxdiv_t;
+.EE
+.SH DESCRIPTION
+.RI [[ l ] l ] div_t
+is the type of the value returned by the
+.RB [[ l ] l ]\c
+.BR div (3)
+function.
+.P
+.I imaxdiv_t
+is the type of the value returned by the
+.BR imaxdiv (3)
+function.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR div (3),
+.BR imaxdiv (3),
+.BR ldiv (3),
+.BR lldiv (3)
diff --git a/man/man3type/double_t.3type b/man/man3type/double_t.3type
new file mode 100644
index 000000000..369867060
--- /dev/null
+++ b/man/man3type/double_t.3type
@@ -0,0 +1,56 @@
+'\" t
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH double_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+float_t, double_t \- most efficient floating types
+.SH LIBRARY
+Math library
+.RI ( libm )
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.P
+.BR typedef " /* ... */ " float_t;
+.BR typedef " /* ... */ " double_t;
+.fi
+.SH DESCRIPTION
+The implementation's most efficient floating types at least as wide as
+.I float
+and
+.I double
+respectively.
+Their type depends on the value of the macro
+.B FLT_EVAL_METHOD
+(defined in
+.IR <float.h> ):
+.P
+.TS
+lB rI rI.
+FLT_EVAL_METHOD	float_t	double_t
+.T&
+n rI rI.
+_
+0	float	double
+1	double	double
+2	long double	long double
+.TE
+.P
+For other values of
+.BR FLT_EVAL_METHOD ,
+the types of
+.I float_t
+and
+.I double_t
+are implementation-defined.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR float.h (0p),
+.BR math.h (0p)
diff --git a/man/man3type/epoll_data.3type b/man/man3type/epoll_data.3type
new file mode 100644
index 000000000..033a55fc4
--- /dev/null
+++ b/man/man3type/epoll_data.3type
@@ -0,0 +1 @@
+.so man3type/epoll_event.3type
diff --git a/man/man3type/epoll_data_t.3type b/man/man3type/epoll_data_t.3type
new file mode 100644
index 000000000..033a55fc4
--- /dev/null
+++ b/man/man3type/epoll_data_t.3type
@@ -0,0 +1 @@
+.so man3type/epoll_event.3type
diff --git a/man/man3type/epoll_event.3type b/man/man3type/epoll_event.3type
new file mode 100644
index 000000000..1e70af79c
--- /dev/null
+++ b/man/man3type/epoll_event.3type
@@ -0,0 +1,55 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH epoll_event 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+epoll_event, epoll_data, epoll_data_t
+\- epoll event
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <sys/epoll.h>
+.P
+.B struct epoll_event {
+.BR "    uint32_t      events;" "  /* Epoll events */"
+.BR "    epoll_data_t  data;" "    /* User data variable */"
+.B };
+.P
+.B union epoll_data {
+.B "    void     *ptr;"
+.B "    int       fd;"
+.B "    uint32_t  u32;"
+.B "    uint64_t  u64;"
+.B };
+.P
+.B "typedef union epoll_data  epoll_data_t;"
+.EE
+.SH DESCRIPTION
+The
+.I epoll_event
+structure specifies data that the kernel should save and
+return when the corresponding file descriptor becomes ready.
+.SH VERSIONS
+.SS C library/kernel differences
+The Linux kernel headers also provide this type,
+with a slightly different definition:
+.P
+.in +4n
+.EX
+#include <linux/eventpoll.h>
+\&
+struct epoll_event {
+    __poll_t  events;
+    __u64     data;
+};
+.EE
+.in
+.SH STANDARDS
+Linux.
+.SH SEE ALSO
+.BR epoll_wait (2),
+.BR epoll_ctl (2)
diff --git a/man/man3type/fenv_t.3type b/man/man3type/fenv_t.3type
new file mode 100644
index 000000000..6b5886665
--- /dev/null
+++ b/man/man3type/fenv_t.3type
@@ -0,0 +1,35 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH fenv_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+fenv_t, fexcept_t \- floating-point environment
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <fenv.h>
+.P
+.BR typedef " /* ... */ " fenv_t;
+.BR typedef " /* ... */ " fexcept_t;
+.fi
+.SH DESCRIPTION
+.I fenv_t
+represents the entire floating-point environment,
+including control modes and status flags.
+.P
+.I fexcept_t
+represents the floating-point status flags collectively.
+.P
+For further details see
+.BR fenv (3).
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH SEE ALSO
+.BR fenv (3)
diff --git a/man/man3type/fexcept_t.3type b/man/man3type/fexcept_t.3type
new file mode 100644
index 000000000..5bedba097
--- /dev/null
+++ b/man/man3type/fexcept_t.3type
@@ -0,0 +1 @@
+.so man3type/fenv_t.3type
diff --git a/man/man3type/float_t.3type b/man/man3type/float_t.3type
new file mode 100644
index 000000000..104734cfe
--- /dev/null
+++ b/man/man3type/float_t.3type
@@ -0,0 +1 @@
+.so man3type/double_t.3type
diff --git a/man/man3type/gid_t.3type b/man/man3type/gid_t.3type
new file mode 100644
index 000000000..52bae7406
--- /dev/null
+++ b/man/man3type/gid_t.3type
@@ -0,0 +1 @@
+.so man3type/id_t.3type
diff --git a/man/man3type/id_t.3type b/man/man3type/id_t.3type
new file mode 100644
index 000000000..3a9450e9e
--- /dev/null
+++ b/man/man3type/id_t.3type
@@ -0,0 +1,110 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH id_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+pid_t, uid_t, gid_t, id_t \- process/user/group identifier
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */ " pid_t;
+.BR typedef " /* ... */ " uid_t;
+.BR typedef " /* ... */ " gid_t;
+.BR typedef " /* ... */ " id_t;
+.fi
+.SH DESCRIPTION
+.I pid_t
+is a type used for storing process IDs, process group IDs, and session IDs.
+It is a signed integer type.
+.P
+.I uid_t
+is a type used to hold user IDs.
+It is an integer type.
+.P
+.I gid_t
+is a type used to hold group IDs.
+It is an integer type.
+.P
+.I id_t
+is a type used to hold a general identifier.
+It is an integer type that can be used to contain a
+.IR pid_t ,
+.IR uid_t ,
+or
+.IR gid_t .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following headers also provide
+.IR pid_t :
+.IR <fcntl.h> ,
+.IR <sched.h> ,
+.IR <signal.h> ,
+.IR <spawn.h> ,
+.IR <sys/msg.h> ,
+.IR <sys/sem.h> ,
+.IR <sys/shm.h> ,
+.IR <sys/wait.h> ,
+.IR <termios.h> ,
+.IR <time.h> ,
+.IR <unistd.h> ,
+and
+.IR <utmpx.h> .
+.P
+The following headers also provide
+.IR uid_t :
+.IR <pwd.h> ,
+.IR <signal.h> ,
+.IR <stropts.h> ,
+.IR <sys/ipc.h> ,
+.IR <sys/stat.h> ,
+and
+.IR <unistd.h> .
+.P
+The following headers also provide
+.IR gid_t :
+.IR <grp.h> ,
+.IR <pwd.h> ,
+.IR <signal.h> ,
+.IR <stropts.h> ,
+.IR <sys/ipc.h> ,
+.IR <sys/stat.h> ,
+and
+.IR <unistd.h> .
+.P
+The following header also provides
+.IR id_t :
+.IR <sys/resource.h> .
+.SH SEE ALSO
+.BR chown (2),
+.BR fork (2),
+.BR getegid (2),
+.BR geteuid (2),
+.BR getgid (2),
+.BR getgroups (2),
+.BR getpgid (2),
+.BR getpid (2),
+.BR getppid (2),
+.BR getpriority (2),
+.BR getpwnam (3),
+.BR getresgid (2),
+.BR getresuid (2),
+.BR getsid (2),
+.BR gettid (2),
+.BR getuid (2),
+.BR kill (2),
+.BR pidfd_open (2),
+.BR sched_setscheduler (2),
+.BR waitid (2),
+.BR getgrnam (3),
+.BR sigqueue (3),
+.BR credentials (7)
diff --git a/man/man3type/imaxdiv_t.3type b/man/man3type/imaxdiv_t.3type
new file mode 100644
index 000000000..3ab8f3447
--- /dev/null
+++ b/man/man3type/imaxdiv_t.3type
@@ -0,0 +1 @@
+.so man3type/div_t.3type
diff --git a/man/man3type/in6_addr.3type b/man/man3type/in6_addr.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/in6_addr.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/in_addr.3type b/man/man3type/in_addr.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/in_addr.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/in_addr_t.3type b/man/man3type/in_addr_t.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/in_addr_t.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/in_port_t.3type b/man/man3type/in_port_t.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/in_port_t.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/int16_t.3type b/man/man3type/int16_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/int16_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/int32_t.3type b/man/man3type/int32_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/int32_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/int64_t.3type b/man/man3type/int64_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/int64_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/int8_t.3type b/man/man3type/int8_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/int8_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/intN_t.3type b/man/man3type/intN_t.3type
new file mode 100644
index 000000000..eefcb33cc
--- /dev/null
+++ b/man/man3type/intN_t.3type
@@ -0,0 +1,177 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH intN_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+intN_t, int8_t, int16_t, int32_t, int64_t,
+uintN_t, uint8_t, uint16_t, uint32_t, uint64_t
+\- fixed-width basic integer types
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdint.h>
+.P
+.BR typedef " /* ... */ " int8_t;
+.BR typedef " /* ... */ " int16_t;
+.BR typedef " /* ... */ " int32_t;
+.BR typedef " /* ... */ " int64_t;
+.P
+.BR typedef " /* ... */ " uint8_t;
+.BR typedef " /* ... */ " uint16_t;
+.BR typedef " /* ... */ " uint32_t;
+.BR typedef " /* ... */ " uint64_t;
+.P
+.B "#define INT8_WIDTH   8"
+.B "#define INT16_WIDTH  16"
+.B "#define INT32_WIDTH  32"
+.B "#define INT64_WIDTH  64"
+.P
+.B "#define UINT8_WIDTH  8"
+.B "#define UINT16_WIDTH 16"
+.B "#define UINT32_WIDTH 32"
+.B "#define UINT64_WIDTH 64"
+.P
+.BR "#define INT8_MAX     " "/*  2**(INT8_WIDTH - 1) - 1   */"
+.BR "#define INT16_MAX    " "/*  2**(INT16_WIDTH - 1) - 1  */"
+.BR "#define INT32_MAX    " "/*  2**(INT32_WIDTH - 1) - 1  */"
+.BR "#define INT64_MAX    " "/*  2**(INT64_WIDTH - 1) - 1  */"
+.P
+.BR "#define INT8_MIN     " "/*  - 2**(INT8_WIDTH - 1)     */"
+.BR "#define INT16_MIN    " "/*  - 2**(INT16_WIDTH - 1)    */"
+.BR "#define INT32_MIN    " "/*  - 2**(INT32_WIDTH - 1)    */"
+.BR "#define INT64_MIN    " "/*  - 2**(INT64_WIDTH - 1)    */"
+.P
+.BR "#define UINT8_MAX    " "/*  2**INT8_WIDTH - 1         */"
+.BR "#define UINT16_MAX   " "/*  2**INT16_WIDTH - 1        */"
+.BR "#define UINT32_MAX   " "/*  2**INT32_WIDTH - 1        */"
+.BR "#define UINT64_MAX   " "/*  2**INT64_WIDTH - 1        */"
+.P
+.BI "#define INT8_C(" c ")    " c " ## " "\fR/* ... */\fP"
+.BI "#define INT16_C(" c ")   " c " ## " "\fR/* ... */\fP"
+.BI "#define INT32_C(" c ")   " c " ## " "\fR/* ... */\fP"
+.BI "#define INT64_C(" c ")   " c " ## " "\fR/* ... */\fP"
+.P
+.BI "#define UINT8_C(" c ")   " c " ## " "\fR/* ... */\fP"
+.BI "#define UINT16_C(" c ")  " c " ## " "\fR/* ... */\fP"
+.BI "#define UINT32_C(" c ")  " c " ## " "\fR/* ... */\fP"
+.BI "#define UINT64_C(" c ")  " c " ## " "\fR/* ... */\fP"
+.fi
+.SH DESCRIPTION
+.IR int N _t
+are
+signed integer types
+of a fixed width of exactly N bits,
+.I N
+being the value specified in its type name.
+They are be capable of storing values in the range
+.RB [ INT \fIN\fP _MIN ,
+.BR INT \fIN\fP _MAX ],
+substituting
+.I N
+by the appropriate number.
+.P
+.IR uint N _t
+are
+unsigned integer types
+of a fixed width of exactly N bits,
+N being the value specified in its type name.
+They are capable of storing values in the range
+.RB [ 0 ,
+.BR UINT \fIN\fP _MAX ],
+substituting
+.I N
+by the appropriate number.
+.P
+According to POSIX,
+.RI [ u ] int8_t ,
+.RI [ u ] int16_t ,
+and
+.RI [ u ] int32_t
+are required;
+.RI [ u ] int64_t
+are only required in implementations that provide integer types with width 64;
+and all other types of this form are optional.
+.P
+The macros
+.RB [ U ] INT \fIN\fP _WIDTH
+expand to the width in bits of these types
+.RI ( N ).
+.P
+The macros
+.RB [ U ] INT \fIN\fP _MAX
+expand to the maximum value that these types can hold.
+.P
+The macros
+.BI INT N _MIN
+expand to the minimum value that these types can hold.
+.P
+The macros
+.RB [ U ] INT \fIN\fP _C ()
+expand their argument to an integer constant of type
+.RI [ u ] int N _t .
+.P
+The length modifiers for the
+.RI [ u ] int N _t
+types for the
+.BR printf (3)
+family of functions
+are expanded by macros of the forms
+.BR PRId \fIN\fP,
+.BR PRIi \fIN\fP,
+.BR PRIu \fIN\fP,
+and
+.BI PRIx N
+(defined in
+.IR <inttypes.h> );
+resulting for example in
+.B %"PRId64"
+or
+.B %"PRIi64"
+for printing
+.I int64_t
+values.
+The length modifiers for the
+.RI [ u ] int N _t
+types for the
+.BR scanf (3)
+family of functions
+are expanded by macros of the forms
+.BR SCNd \fIN\fP,
+.BR SCNi \fIN\fP,
+.BR SCNu \fIN\fP,
+and
+.BI SCNx N,
+(defined in
+.IR <inttypes.h> );
+resulting for example in
+.B %"SCNu8"
+or
+.B %"SCNx8"
+for scanning
+.I uint8_t
+values.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.P
+The
+.RB [ U ] INT \fIN\fP _WIDTH
+macros were added in C23.
+.SH NOTES
+The following header also provides these types:
+.IR <inttypes.h> .
+.I <arpa/inet.h>
+also provides
+.I uint16_t
+and
+.IR uint32_t .
+.SH SEE ALSO
+.BR intmax_t (3type),
+.BR intptr_t (3type),
+.BR printf (3)
diff --git a/man/man3type/intmax_t.3type b/man/man3type/intmax_t.3type
new file mode 100644
index 000000000..dba108114
--- /dev/null
+++ b/man/man3type/intmax_t.3type
@@ -0,0 +1,97 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH intmax_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+intmax_t, uintmax_t \- greatest-width basic integer types
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdint.h>
+.P
+.BR typedef " /* ... */ " intmax_t;
+.BR typedef " /* ... */ " uintmax_t;
+.P
+.BR "#define INTMAX_WIDTH  " "/* ... */"
+.B "#define UINTMAX_WIDTH INTMAX_WIDTH"
+.P
+.BR "#define INTMAX_MAX    " "/*  2**(INTMAX_WIDTH - 1) - 1  */"
+.BR "#define INTMAX_MIN    " "/*  - 2**(INTMAX_WIDTH - 1)    */"
+.BR "#define UINTMAX_MAX   " "/*  2**UINTMAX_WIDTH - 1       */"
+.P
+.BI "#define INTMAX_C(" c ) "   c " ## " \fR/* ... */\fP"
+.BI "#define UINTMAX_C(" c ) "  c " ## " \fR/* ... */\fP"
+.fi
+.SH DESCRIPTION
+.I intmax_t
+is a signed integer type
+capable of representing any value of any basic signed integer type
+supported by the implementation.
+It is capable of storing values in the range
+.RB [ INTMAX_MIN ,
+.BR INTMAX_MAX ].
+.P
+.I uintmax_t
+is an unsigned integer type
+capable of representing any value of any basic unsigned integer type
+supported by the implementation.
+It is capable of storing values in the range
+.RB [ 0 ,
+.BR UINTMAX_MAX ].
+.P
+The macros
+.RB [ U ] INTMAX_WIDTH
+expand to the width in bits of these types.
+.P
+The macros
+.RB [ U ] INTMAX_MAX
+expand to the maximum value that these types can hold.
+.P
+The macro
+.B INTMAX_MIN
+expands to the minimum value that
+.I intmax_t
+can hold.
+.P
+The macros
+.RB [ U ] INTMAX_C ()
+expand their argument to an integer constant of type
+.RI [ u ] intmax_t .
+.P
+The length modifier for
+.RI [ u ] intmax_t
+for the
+.BR printf (3)
+and the
+.BR scanf (3)
+families of functions is
+.BR j ;
+resulting commonly in
+.BR %jd ,
+.BR %ji ,
+.BR %ju ,
+or
+.B %jx
+for printing
+.RI [ u ] intmax_t
+values.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH NOTES
+The following header also provides these types:
+.IR <inttypes.h> .
+.SH BUGS
+These types may not be as large as extended integer types, such as
+.I __int128
+.SH SEE ALSO
+.BR int64_t (3type),
+.BR intptr_t (3type),
+.BR printf (3),
+.BR strtoimax (3)
diff --git a/man/man3type/intptr_t.3type b/man/man3type/intptr_t.3type
new file mode 100644
index 000000000..ac7b18214
--- /dev/null
+++ b/man/man3type/intptr_t.3type
@@ -0,0 +1,107 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH intptr_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+intptr_t, uintptr_t \- integer types wide enough to hold pointers
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdint.h>
+.P
+.BR typedef " /* ... */ " intptr_t;
+.BR typedef " /* ... */ " uintptr_t;
+.P
+.BR "#define INTPTR_WIDTH" "  /* ... */"
+.B #define UINTPTR_WIDTH INTPTR_WIDTH
+.P
+.BR "#define INTPTR_MAX" "    /*  2**(INTPTR_WIDTH \- 1) \- 1  */"
+.BR "#define INTPTR_MIN" "    /*  \- 2**(INTPTR_WIDTH \- 1)    */"
+.BR "#define UINTPTR_MAX" "   /*  2**UINTPTR_WIDTH \- 1       */"
+.fi
+.SH DESCRIPTION
+.I intptr_t
+is a signed integer type
+such that any valid
+.RI ( "void *" )
+value can be converted to this type and then converted back.
+It is capable of storing values in the range
+.RB [ INTPTR_MIN ,
+.BR INTPTR_MAX ].
+.P
+.I uintptr_t
+is an unsigned integer type
+such that any valid
+.RI ( "void *" )
+value can be converted to this type and then converted back.
+It is capable of storing values in the range
+.RB [ 0 ,
+.BR INTPTR_MAX ].
+.P
+The macros
+.RB [ U ] INTPTR_WIDTH
+expand to the width in bits of these types.
+.P
+The macros
+.RB [ U ] INTPTR_MAX
+expand to the maximum value that these types can hold.
+.P
+The macro
+.B INTPTR_MIN
+expands to the minimum value that
+.I intptr_t
+can hold.
+.P
+The length modifiers for the
+.RI [ u ] intptr_t
+types
+for the
+.BR printf (3)
+family of functions
+are expanded by the macros
+.BR PRIdPTR ,
+.BR PRIiPTR ,
+and
+.B PRIuPTR
+(defined in
+.IR <inttypes.h> );
+resulting commonly in
+.B %"PRIdPTR"
+or
+.B %"PRIiPTR"
+for printing
+.I intptr_t
+values.
+The length modifiers for the
+.IR [ u ] intptr_t
+types
+for the
+.BR scanf (3)
+family of functions
+are expanded by the macros
+.BR SCNdPTR ,
+.BR SCNiPTR ,
+and
+.B SCNuPTR
+(defined in
+.IR <inttypes.h> );
+resulting commonly in
+.B %"SCNuPTR"
+for scanning
+.I uintptr_t
+values.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C99, POSIX.1-2001.
+.SH NOTES
+The following header also provides these types:
+.IR <inttypes.h> .
+.SH SEE ALSO
+.BR intmax_t (3type),
+.BR void (3)
diff --git a/man/man3type/iovec.3type b/man/man3type/iovec.3type
new file mode 100644
index 000000000..14d2c40f4
--- /dev/null
+++ b/man/man3type/iovec.3type
@@ -0,0 +1,49 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH iovec 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+iovec \- Vector I/O data structure
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <sys/uio.h>
+.P
+.B struct iovec {
+.BR "    void   *iov_base;" "  /* Starting address */"
+.BR "    size_t  iov_len;" "   /* Size of the memory pointed to by "\c
+.IR iov_base ". */"
+.B };
+.EE
+.SH DESCRIPTION
+Describes a region of memory, beginning at
+.I iov_base
+address and with the size of
+.I iov_len
+bytes.
+System calls use arrays of this structure,
+where each element of the array represents a memory region,
+and the whole array represents a vector of memory regions.
+The maximum number of
+.I iovec
+structures in that array
+is limited by
+.B IOV_MAX
+(defined in
+.IR <limits.h> ,
+or accessible via the call
+.IR sysconf(_SC_IOV_MAX) ).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following header also provides this type:
+.IR <sys/socket.h> .
+.SH SEE ALSO
+.BR process_madvise (2),
+.BR readv (2)
diff --git a/man/man3type/itimerspec.3type b/man/man3type/itimerspec.3type
new file mode 100644
index 000000000..d6413d218
--- /dev/null
+++ b/man/man3type/itimerspec.3type
@@ -0,0 +1,32 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH itimerspec 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+itimerspec \- interval for a timer with nanosecond precision
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <time.h>
+.P
+.B struct itimerspec {
+.BR "    struct timespec  it_interval;" "  /* Interval for periodic timer */"
+.BR "    struct timespec  it_value;" "     /* Initial expiration */"
+.B };
+.EE
+.SH DESCRIPTION
+Describes the initial expiration of a timer,
+and its interval,
+in seconds and nanoseconds.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR timerfd_create (2),
+.BR timer_settime (2),
+.BR timespec (3type)
diff --git a/man/man3type/lconv.3type b/man/man3type/lconv.3type
new file mode 100644
index 000000000..5757cd068
--- /dev/null
+++ b/man/man3type/lconv.3type
@@ -0,0 +1,56 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH lconv 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+lconv \- numeric formatting information
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <locale.h>
+.P
+.BR "struct lconv {" "                /* Values in the \[dq]C\[dq] locale: */"
+.BR "    char *decimal_point;" "      /* \[dq].\[dq] */"
+.BR "    char *thousands_sep;" "      /* \[dq]\[dq] */"
+.BR "    char *grouping;" "           /* \[dq]\[dq] */"
+.BR "    char *mon_decimal_point;" "  /* \[dq]\[dq] */"
+.BR "    char *mon_thousands_sep;" "  /* \[dq]\[dq] */"
+.BR "    char *mon_grouping;" "       /* \[dq]\[dq] */"
+.BR "    char *positive_sign;" "      /* \[dq]\[dq] */"
+.BR "    char *negative_sign;" "      /* \[dq]\[dq] */"
+.BR "    char *currency_symbol;" "    /* \[dq]\[dq] */"
+.BR "    char  frac_digits;" "        /* CHAR_MAX */"
+.BR "    char  p_cs_precedes;" "      /* CHAR_MAX */"
+.BR "    char  n_cs_precedes;" "      /* CHAR_MAX */"
+.BR "    char  p_sep_by_space;" "     /* CHAR_MAX */"
+.BR "    char  n_sep_by_space;" "     /* CHAR_MAX */"
+.BR "    char  p_sign_posn;" "        /* CHAR_MAX */"
+.BR "    char  n_sign_posn;" "        /* CHAR_MAX */"
+.BR "    char *int_curr_symbol;" "    /* \[dq]\[dq] */"
+.BR "    char  int_frac_digits;" "    /* CHAR_MAX */"
+.BR "    char  int_p_cs_precedes;" "  /* CHAR_MAX */"
+.BR "    char  int_n_cs_precedes;" "  /* CHAR_MAX */"
+.BR "    char  int_p_sep_by_space;" " /* CHAR_MAX */"
+.BR "    char  int_n_sep_by_space;" " /* CHAR_MAX */"
+.BR "    char  int_p_sign_posn;" "    /* CHAR_MAX */"
+.BR "    char  int_n_sign_posn;" "    /* CHAR_MAX */"
+.B };
+.EE
+.SH DESCRIPTION
+Contains members related to the formatting of numeric values.
+In the "C" locale, its members have the values
+shown in the comments above.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH SEE ALSO
+.BR setlocale (3),
+.BR localeconv (3),
+.BR charsets (7),
+.BR locale (7)
diff --git a/man/man3type/ldiv_t.3type b/man/man3type/ldiv_t.3type
new file mode 100644
index 000000000..3ab8f3447
--- /dev/null
+++ b/man/man3type/ldiv_t.3type
@@ -0,0 +1 @@
+.so man3type/div_t.3type
diff --git a/man/man3type/lldiv_t.3type b/man/man3type/lldiv_t.3type
new file mode 100644
index 000000000..3ab8f3447
--- /dev/null
+++ b/man/man3type/lldiv_t.3type
@@ -0,0 +1 @@
+.so man3type/div_t.3type
diff --git a/man/man3type/loff_t.3type b/man/man3type/loff_t.3type
new file mode 100644
index 000000000..e59af3f11
--- /dev/null
+++ b/man/man3type/loff_t.3type
@@ -0,0 +1 @@
+.so man3type/off_t.3type
diff --git a/man/man3type/mode_t.3type b/man/man3type/mode_t.3type
new file mode 100644
index 000000000..c332eeb75
--- /dev/null
+++ b/man/man3type/mode_t.3type
@@ -0,0 +1,40 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH mode_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+mode_t \- file attributes
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */ " mode_t;
+.fi
+.SH DESCRIPTION
+Used for some file attributes (e.g., file mode).
+It is an integer type.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following headers also provide this type:
+.IR <fcntl.h> ,
+.IR <ndbm.h> ,
+.IR <spawn.h> ,
+.IR <sys/ipc.h> ,
+.IR <sys/mman.h> ,
+and
+.IR <sys/stat.h> .
+.SH SEE ALSO
+.BR chmod (2),
+.BR mkdir (2),
+.BR open (2),
+.BR umask (2),
+.BR stat (3type)
diff --git a/man/man3type/off64_t.3type b/man/man3type/off64_t.3type
new file mode 100644
index 000000000..e59af3f11
--- /dev/null
+++ b/man/man3type/off64_t.3type
@@ -0,0 +1 @@
+.so man3type/off_t.3type
diff --git a/man/man3type/off_t.3type b/man/man3type/off_t.3type
new file mode 100644
index 000000000..4b3838917
--- /dev/null
+++ b/man/man3type/off_t.3type
@@ -0,0 +1,92 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH off_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+off_t, off64_t, loff_t \- file sizes
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */  " off_t;
+.P
+.B #define _LARGEFILE64_SOURCE
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */  " off64_t;
+.P
+.B #define _GNU_SOURCE
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */  " loff_t;
+.fi
+.SH DESCRIPTION
+.I off_t
+is used for describing file sizes.
+It is a signed integer type.
+.P
+.I off64_t
+is a 64-bit version of the type,
+used in glibc.
+.P
+.I loff_t
+is a 64-bit version of the type,
+introduced by the Linux kernel.
+.SH STANDARDS
+.TP
+.I off_t
+POSIX.1-2008.
+.TP
+.I off64_t
+GNU and some BSDs.
+.TP
+.I loff_t
+Linux.
+.SH VERSIONS
+.TP
+.I off_t
+POSIX.1-2001.
+.P
+.I <aio.h>
+and
+.I <stdio.h>
+define
+.I off_t
+since POSIX.1-2008.
+.SH NOTES
+On some architectures,
+the width of
+.I off_t
+can be controlled with the feature test macro
+.BR _FILE_OFFSET_BITS .
+.P
+The following headers also provide
+.IR off_t :
+.IR <aio.h> ,
+.IR <fcntl.h> ,
+.IR <stdio.h> ,
+.IR <sys/mman.h> ,
+.IR <sys/stat.h> ,
+and
+.IR <unistd.h> .
+.SH SEE ALSO
+.BR copy_file_range (2),
+.BR llseek (2),
+.BR lseek (2),
+.BR mmap (2),
+.BR posix_fadvise (2),
+.BR pread (2),
+.BR readahead (2),
+.BR sync_file_range (2),
+.BR truncate (2),
+.BR fseeko (3),
+.BR lockf (3),
+.BR lseek64 (3),
+.BR posix_fallocate (3),
+.BR feature_test_macros (7)
diff --git a/man/man3type/pid_t.3type b/man/man3type/pid_t.3type
new file mode 100644
index 000000000..52bae7406
--- /dev/null
+++ b/man/man3type/pid_t.3type
@@ -0,0 +1 @@
+.so man3type/id_t.3type
diff --git a/man/man3type/printf_arginfo_size_function.3type b/man/man3type/printf_arginfo_size_function.3type
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3type/printf_arginfo_size_function.3type
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3type/printf_function.3type b/man/man3type/printf_function.3type
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3type/printf_function.3type
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3type/printf_info.3type b/man/man3type/printf_info.3type
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3type/printf_info.3type
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3type/printf_va_arg_function.3type b/man/man3type/printf_va_arg_function.3type
new file mode 100644
index 000000000..ad10bad38
--- /dev/null
+++ b/man/man3type/printf_va_arg_function.3type
@@ -0,0 +1 @@
+.so man3head/printf.h.3head
diff --git a/man/man3type/ptrdiff_t.3type b/man/man3type/ptrdiff_t.3type
new file mode 100644
index 000000000..5a881dd9b
--- /dev/null
+++ b/man/man3type/ptrdiff_t.3type
@@ -0,0 +1,47 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH ptrdiff_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+ptrdiff_t \- count of elements or array index
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stddef.h>
+.P
+.BR typedef " /* ... */  " ptrdiff_t;
+.fi
+.SH DESCRIPTION
+Used for a count of elements, or an array index.
+It is the result of subtracting two pointers.
+It is a signed integer type
+capable of storing values in the range
+.RB [ PTRDIFF_MIN ,
+.BR PTRDIFF_MAX ].
+.P
+The length modifier for
+.I ptrdiff_t
+for the
+.BR printf (3)
+and the
+.BR scanf (3)
+families of functions is
+.BR t ,
+resulting commonly in
+.B %td
+or
+.B %ti
+for printing
+.I ptrdiff_t
+values.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH SEE ALSO
+.BR size_t (3type)
diff --git a/man/man3type/regex_t.3type b/man/man3type/regex_t.3type
new file mode 100644
index 000000000..c0daaf0ff
--- /dev/null
+++ b/man/man3type/regex_t.3type
@@ -0,0 +1 @@
+.so man3/regex.3
diff --git a/man/man3type/regmatch_t.3type b/man/man3type/regmatch_t.3type
new file mode 100644
index 000000000..c0daaf0ff
--- /dev/null
+++ b/man/man3type/regmatch_t.3type
@@ -0,0 +1 @@
+.so man3/regex.3
diff --git a/man/man3type/regoff_t.3type b/man/man3type/regoff_t.3type
new file mode 100644
index 000000000..c0daaf0ff
--- /dev/null
+++ b/man/man3type/regoff_t.3type
@@ -0,0 +1 @@
+.so man3/regex.3
diff --git a/man/man3type/sa_family_t.3type b/man/man3type/sa_family_t.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/sa_family_t.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/sigevent.3type b/man/man3type/sigevent.3type
new file mode 100644
index 000000000..01ca76620
--- /dev/null
+++ b/man/man3type/sigevent.3type
@@ -0,0 +1,142 @@
+.\" Copyright (c) 2006, 2010, 2020, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2009 Petr Baudis <pasky@suse.cz>
+.\" Copyright (c) 2020-2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sigevent 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+sigevent, sigval \- structure for notification from asynchronous routines
+.SH SYNOPSIS
+.EX
+.B #include <signal.h>
+.P
+.B struct sigevent {
+.BR "    int             sigev_notify;" "  /* Notification type */"
+.BR "    int             sigev_signo;" "   /* Signal number */"
+.BR "    union sigval    sigev_value;" "   /* Data passed with notification */"
+\&
+.B  "    void          (*sigev_notify_function)(union sigval);"
+.BR "                                " "   /* Notification function"
+.BR "                                " "      (SIGEV_THREAD) */"
+.B  "    pthread_attr_t *sigev_notify_attributes;"
+.BR "                                " "   /* Notification attributes */"
+\&
+.BR "    " "/* Linux only: */"
+.B  "    pid_t           sigev_notify_thread_id;"
+.BR "                                " "   /* ID of thread to signal"
+.BR "                                " "      (SIGEV_THREAD_ID) */"
+.B };
+.P
+.BR "union sigval {" "                     /* Data passed with notification */"
+.BR "    int             sival_int;" "     /* Integer value */"
+.BR "    void           *sival_ptr;" "     /* Pointer value */"
+.B };
+.EE
+.SH DESCRIPTION
+.SS sigevent
+The
+.I sigevent
+structure is used by various APIs
+to describe the way a process is to be notified about an event
+(e.g., completion of an asynchronous request, expiration of a timer,
+or the arrival of a message).
+.P
+The definition shown in the SYNOPSIS is approximate:
+some of the fields in the
+.I sigevent
+structure may be defined as part of a union.
+Programs should employ only those fields relevant
+to the value specified in
+.IR sigev_notify .
+.P
+The
+.I sigev_notify
+field specifies how notification is to be performed.
+This field can have one of the following values:
+.TP
+.B SIGEV_NONE
+A "null" notification: don't do anything when the event occurs.
+.TP
+.B SIGEV_SIGNAL
+Notify the process by sending the signal specified in
+.IR sigev_signo .
+.IP
+If the signal is caught with a signal handler that was registered using the
+.BR sigaction (2)
+.B SA_SIGINFO
+flag, then the following fields are set in the
+.I siginfo_t
+structure that is passed as the second argument of the handler:
+.RS
+.TP 10
+.I si_code
+This field is set to a value that depends on the API
+delivering the notification.
+.TP
+.I si_signo
+This field is set to the signal number (i.e., the same value as in
+.IR sigev_signo ).
+.TP
+.I si_value
+This field is set to the value specified in
+.IR sigev_value .
+.RE
+.IP
+Depending on the API, other fields may also be set in the
+.I siginfo_t
+structure.
+.IP
+The same information is also available if the signal is accepted using
+.BR sigwaitinfo (2).
+.TP
+.B SIGEV_THREAD
+Notify the process by invoking
+.I sigev_notify_function
+"as if" it were the start function of a new thread.
+(Among the implementation possibilities here are that
+each timer notification could result in the creation of a new thread,
+or that a single thread is created to receive all notifications.)
+The function is invoked with
+.I sigev_value
+as its sole argument.
+If
+.I sigev_notify_attributes
+is not NULL, it should point to a
+.I pthread_attr_t
+structure that defines attributes for the new thread (see
+.BR pthread_attr_init (3)).
+.TP
+.BR SIGEV_THREAD_ID " (Linux-specific)"
+.\" | SIGEV_SIGNAL vs not?
+Currently used only by POSIX timers; see
+.BR timer_create (2).
+.SS sigval
+Data passed with a signal.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+.I <aio.h>
+and
+.I <time.h>
+define
+.I sigevent
+since POSIX.1-2008.
+.SH NOTES
+The following headers also provide
+.IR sigevent :
+.IR <aio.h> ,
+.IR <mqueue.h> ,
+and
+.IR <time.h> .
+.SH SEE ALSO
+.BR timer_create (2),
+.BR getaddrinfo_a (3),
+.BR lio_listio (3),
+.BR mq_notify (3),
+.BR pthread_sigqueue (3),
+.BR sigqueue (3),
+.BR aiocb (3type),
+.BR siginfo_t (3type)
diff --git a/man/man3type/siginfo_t.3type b/man/man3type/siginfo_t.3type
new file mode 100644
index 000000000..db50c0f09
--- /dev/null
+++ b/man/man3type/siginfo_t.3type
@@ -0,0 +1 @@
+.so man7/system_data_types.7
diff --git a/man/man3type/sigset_t.3type b/man/man3type/sigset_t.3type
new file mode 100644
index 000000000..db50c0f09
--- /dev/null
+++ b/man/man3type/sigset_t.3type
@@ -0,0 +1 @@
+.so man7/system_data_types.7
diff --git a/man/man3type/sigval.3type b/man/man3type/sigval.3type
new file mode 100644
index 000000000..b43f1bbe8
--- /dev/null
+++ b/man/man3type/sigval.3type
@@ -0,0 +1 @@
+.so man3type/sigevent.3type
diff --git a/man/man3type/size_t.3type b/man/man3type/size_t.3type
new file mode 100644
index 000000000..92efc8139
--- /dev/null
+++ b/man/man3type/size_t.3type
@@ -0,0 +1,181 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH size_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+size_t, ssize_t \- count of bytes
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stddef.h>
+.P
+.BR typedef " /* ... */  " size_t;
+.P
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */  " ssize_t;
+.fi
+.SH DESCRIPTION
+.TP
+.I size_t
+Used for a count of bytes.
+It is the result of the
+.IR sizeof ()
+operator.
+It is an unsigned integer type
+capable of storing values in the range
+.RB [ 0 ,
+.BR SIZE_MAX ].
+.TP
+.I ssize_t
+Used for a count of bytes or an error indication.
+It is a signed integer type
+capable of storing values at least in the range
+.RB [ \-1 ,
+.BR SSIZE_MAX ].
+.SS Use with printf(3) and scanf(3)
+.TP
+.I size_t
+The length modifier for
+.I size_t
+for the
+.BR printf (3)
+and the
+.BR scanf (3)
+families of functions is
+.BR z ,
+resulting commonly in
+.B %zu
+or
+.B %zx
+for printing
+.I size_t
+values.
+.TP
+.I ssize_t
+glibc and most other implementations provide a length modifier for
+.I ssize_t
+for the
+.BR printf (3)
+and the
+.BR scanf (3)
+families of functions,
+which is
+.BR z ;
+resulting commonly in
+.B %zd
+or
+.B %zi
+for printing
+.I ssize_t
+values.
+Although
+.B z
+works for
+.I ssize_t
+on most implementations,
+portable POSIX programs should avoid using it\[em]for example,
+by converting the value to
+.I intmax_t
+and using its length modifier
+.RB ( j ).
+.SH STANDARDS
+.TP
+.I size_t
+C11, POSIX.1-2008.
+.TP
+.I ssize_t
+POSIX.1-2008.
+.PD
+.SH HISTORY
+.TP
+.I size_t
+C89, POSIX.1-2001.
+.TP
+.I ssize_t
+POSIX.1-2001.
+.P
+.IR <aio.h> ,
+.IR <glob.h> ,
+.IR <grp.h> ,
+.IR <iconv.h> ,
+.IR <mqueue.h> ,
+.IR <pwd.h> ,
+.IR <signal.h> ,
+and
+.I <sys/socket.h>
+define
+.I size_t
+since POSIX.1-2008.
+.P
+.IR <aio.h> ,
+.IR <mqueue.h> ,
+and
+.I <sys/socket.h>
+define
+.I ssize_t
+since POSIX.1-2008.
+.SH NOTES
+.TP
+.I size_t
+The following headers also provide
+.IR size_t :
+.IR <aio.h> ,
+.IR <glob.h> ,
+.IR <grp.h> ,
+.IR <iconv.h> ,
+.IR <monetary.h> ,
+.IR <mqueue.h> ,
+.IR <ndbm.h> ,
+.IR <pwd.h> ,
+.IR <regex.h> ,
+.IR <search.h> ,
+.IR <signal.h> ,
+.IR <stdio.h> ,
+.IR <stdlib.h> ,
+.IR <string.h> ,
+.IR <strings.h> ,
+.IR <sys/mman.h> ,
+.IR <sys/msg.h> ,
+.IR <sys/sem.h> ,
+.IR <sys/shm.h> ,
+.IR <sys/socket.h> ,
+.IR <sys/types.h> ,
+.IR <sys/uio.h> ,
+.IR <time.h> ,
+.IR <unistd.h> ,
+.IR <wchar.h> ,
+and
+.IR <wordexp.h> .
+.TP
+.I ssize_t
+The following headers also provide
+.IR ssize_t :
+.IR <aio.h> ,
+.IR <monetary.h> ,
+.IR <mqueue.h> ,
+.IR <stdio.h> ,
+.IR <sys/msg.h> ,
+.IR <sys/socket.h> ,
+.IR <sys/uio.h> ,
+and
+.IR <unistd.h> .
+.SH SEE ALSO
+.BR read (2),
+.BR readlink (2),
+.BR readv (2),
+.BR recv (2),
+.BR send (2),
+.BR write (2),
+.BR fread (3),
+.BR fwrite (3),
+.BR memcmp (3),
+.BR memcpy (3),
+.BR memset (3),
+.BR offsetof (3),
+.BR ptrdiff_t (3type)
diff --git a/man/man3type/sockaddr.3type b/man/man3type/sockaddr.3type
new file mode 100644
index 000000000..10659ca45
--- /dev/null
+++ b/man/man3type/sockaddr.3type
@@ -0,0 +1,154 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH sockaddr 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+sockaddr, sockaddr_storage, sockaddr_in, sockaddr_in6, sockaddr_un, socklen_t,
+in_addr, in6_addr, in_addr_t, in_port_t,
+\- socket address
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <sys/socket.h>
+.P
+.B struct sockaddr {
+.BR "    sa_family_t     sa_family;" "      /* Address family */"
+.BR "    char            sa_data[];" "      /* Socket address */"
+.B };
+.P
+.B struct sockaddr_storage {
+.BR "    sa_family_t     ss_family;" "      /* Address family */"
+.B };
+.P
+.BR typedef " /* ... */ " socklen_t;
+.BR typedef " /* ... */ " sa_family_t;
+.P
+.EE
+.SS Internet domain sockets
+.EX
+.B #include <netinet/in.h>
+.P
+.B struct sockaddr_in {
+.BR "    sa_family_t     sin_family;" "     /* " AF_INET " */"
+.BR "    in_port_t       sin_port;" "       /* Port number */"
+.BR "    struct in_addr  sin_addr;" "       /* IPv4 address */"
+.B };
+.P
+.B struct sockaddr_in6 {
+.BR "    sa_family_t     sin6_family;" "    /* " AF_INET6 " */"
+.BR "    in_port_t       sin6_port;" "      /* Port number */"
+.BR "    uint32_t        sin6_flowinfo;" "  /* IPv6 flow info */"
+.BR "    struct in6_addr sin6_addr;" "      /* IPv6 address */"
+.BR "    uint32_t        sin6_scope_id;" "  /* Set of interfaces for a scope */"
+.B };
+.P
+.B struct in_addr {
+.B "    in_addr_t s_addr;"
+.B };
+.P
+.B struct in6_addr {
+.B "    uint8_t   s6_addr[16];"
+.B };
+.P
+.B typedef uint32_t in_addr_t;
+.B typedef uint16_t in_port_t;
+.EE
+.SS UNIX domain sockets
+.EX
+.B #include <sys/un.h>
+.P
+.B struct sockaddr_un {
+.BR "    sa_family_t     sun_family;" "     /* Address family */"
+.BR "    char            sun_path[];" "     /* Socket pathname */"
+.B };
+.EE
+.SH DESCRIPTION
+.TP
+.I sockaddr
+Describes a socket address.
+.TP
+.I sockaddr_storage
+A structure at least as large as any other
+.IR sockaddr_ *
+address structures.
+It's aligned so that a pointer to it can be cast
+as a pointer to other
+.IR sockaddr_ *
+structures and used to access its fields.
+.TP
+.I socklen_t
+Describes the length of a socket address.
+This is an integer type of at least 32 bits.
+.TP
+.I sa_family_t
+Describes a socket's protocol family.
+This is an unsigned integer type.
+.SS Internet domain sockets
+.TP
+.I sockaddr_in
+Describes an IPv4 Internet domain socket address.
+The
+.I sin_port
+and
+.I sin_addr
+members are stored in network byte order.
+.TP
+.I sockaddr_in6
+Describes an IPv6 Internet domain socket address.
+The
+.I sin6_addr.s6_addr
+array is used to contain a 128-bit IPv6 address,
+stored in network byte order.
+.SS UNIX domain sockets
+.TP
+.I sockaddr_un
+Describes a UNIX domain socket address.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+.I socklen_t
+was invented by POSIX.
+See also
+.BR accept (2).
+.P
+These structures were invented before modern ISO C strict-aliasing rules.
+If aliasing rules are applied strictly,
+these structures would be extremely difficult to use
+without invoking Undefined Behavior.
+POSIX Issue 8 will fix this by requiring that implementations
+make sure that these structures
+can be safely used as they were designed.
+.SH NOTES
+.I socklen_t
+is also defined in
+.IR <netdb.h> .
+.P
+.I sa_family_t
+is also defined in
+.I <netinet/in.h>
+and
+.IR <sys/un.h> .
+.SH SEE ALSO
+.BR accept (2),
+.BR bind (2),
+.BR connect (2),
+.BR getpeername (2),
+.BR getsockname (2),
+.BR getsockopt (2),
+.BR sendto (2),
+.BR setsockopt (2),
+.BR socket (2),
+.BR socketpair (2),
+.BR getaddrinfo (3),
+.BR gethostbyaddr (3),
+.BR getnameinfo (3),
+.BR htonl (3),
+.BR ipv6 (7),
+.BR socket (7)
diff --git a/man/man3type/sockaddr_in.3type b/man/man3type/sockaddr_in.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/sockaddr_in.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/sockaddr_in6.3type b/man/man3type/sockaddr_in6.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/sockaddr_in6.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/sockaddr_storage.3type b/man/man3type/sockaddr_storage.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/sockaddr_storage.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/sockaddr_un.3type b/man/man3type/sockaddr_un.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/sockaddr_un.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/socklen_t.3type b/man/man3type/socklen_t.3type
new file mode 100644
index 000000000..39e914c30
--- /dev/null
+++ b/man/man3type/socklen_t.3type
@@ -0,0 +1 @@
+.so man3type/sockaddr.3type
diff --git a/man/man3type/speed_t.3type b/man/man3type/speed_t.3type
new file mode 100644
index 000000000..26cfd0171
--- /dev/null
+++ b/man/man3type/speed_t.3type
@@ -0,0 +1 @@
+.so man3type/cc_t.3type
diff --git a/man/man3type/ssize_t.3type b/man/man3type/ssize_t.3type
new file mode 100644
index 000000000..c8d440814
--- /dev/null
+++ b/man/man3type/ssize_t.3type
@@ -0,0 +1 @@
+.so man3type/size_t.3type
diff --git a/man/man3type/stat.3type b/man/man3type/stat.3type
new file mode 100644
index 000000000..0eddda880
--- /dev/null
+++ b/man/man3type/stat.3type
@@ -0,0 +1,162 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH stat 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+stat \- file status
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <sys/stat.h>
+.P
+.B struct stat {
+.BR "    dev_t      st_dev;" "      /* ID of device containing file */"
+.BR "    ino_t      st_ino;" "      /* Inode number */"
+.BR "    mode_t     st_mode;" "     /* File type and mode */"
+.BR "    nlink_t    st_nlink;" "    /* Number of hard links */"
+.BR "    uid_t      st_uid;" "      /* User ID of owner */"
+.BR "    gid_t      st_gid;" "      /* Group ID of owner */"
+.BR "    dev_t      st_rdev;" "     /* Device ID (if special file) */"
+.BR "    off_t      st_size;" "     /* Total size, in bytes */"
+.BR "    blksize_t  st_blksize;" "  /* Block size for filesystem I/O */"
+.BR "    blkcnt_t   st_blocks;" "   /* Number of 512 B blocks allocated */"
+\&
+    /* Since POSIX.1-2008, this structure supports nanosecond
+       precision for the following timestamp fields.
+       For the details before POSIX.1-2008, see VERSIONS. */
+\&
+.BR "    struct timespec  st_atim;" "  /* Time of last access */"
+.BR "    struct timespec  st_mtim;" "  /* Time of last modification */"
+.BR "    struct timespec  st_ctim;" "  /* Time of last status change */"
+\&
+.BR "#define st_atime  st_atim.tv_sec" "  /* Backward compatibility */"
+.B "#define st_mtime  st_mtim.tv_sec"
+.B "#define st_ctime  st_ctim.tv_sec"
+.B };
+.EE
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.IR st_atim ,
+.IR st_mtim ,
+.IR st_ctim :
+.nf
+    Since glibc 2.12:
+        _POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700
+    glibc 2.19 and earlier:
+        _BSD_SOURCE || _SVID_SOURCE
+.fi
+.SH DESCRIPTION
+Describes information about a file.
+.P
+The fields are as follows:
+.TP
+.I st_dev
+This field describes the device on which this file resides.
+(The
+.BR major (3)
+and
+.BR minor (3)
+macros may be useful to decompose the device ID in this field.)
+.TP
+.I st_ino
+This field contains the file's inode number.
+.TP
+.I st_mode
+This field contains the file type and mode.
+See
+.BR inode (7)
+for further information.
+.TP
+.I st_nlink
+This field contains the number of hard links to the file.
+.TP
+.I st_uid
+This field contains the user ID of the owner of the file.
+.TP
+.I st_gid
+This field contains the ID of the group owner of the file.
+.TP
+.I st_rdev
+This field describes the device that this file (inode) represents.
+.TP
+.I st_size
+This field gives the size of the file (if it is a regular
+file or a symbolic link) in bytes.
+The size of a symbolic link is the length of the pathname
+it contains, without a terminating null byte.
+.TP
+.I st_blksize
+This field gives the "preferred" block size for efficient filesystem I/O.
+.TP
+.I st_blocks
+This field indicates the number of blocks allocated to the file,
+in 512-byte units.
+(This may be smaller than
+.IR st_size /512
+when the file has holes.)
+.TP
+.I st_atime
+This is the time of the last access of file data.
+.TP
+.I st_mtime
+This is the time of last modification of file data.
+.TP
+.I st_ctime
+This is the file's last status change timestamp
+(time of last change to the inode).
+.P
+For further information on the above fields, see
+.BR inode (7).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+Old kernels and old standards did not support nanosecond timestamp fields.
+Instead, there were three timestamp
+.RI fields\[em] st_atime ,
+.IR st_mtime ,
+and
+.IR st_ctime \[em]typed
+as
+.I time_t
+that recorded timestamps with one-second precision.
+.P
+Since Linux 2.5.48, the
+.I stat
+structure supports nanosecond resolution for the three file timestamp fields.
+The nanosecond components of each timestamp are available
+via names of the form
+.IR st_atim.tv_nsec ,
+if suitable test macros are defined.
+Nanosecond timestamps were standardized in POSIX.1-2008,
+and, starting with glibc 2.12,
+glibc exposes the nanosecond component names if
+.B _POSIX_C_SOURCE
+is defined with the value 200809L or greater, or
+.B _XOPEN_SOURCE
+is defined with the value 700 or greater.
+Up to and including glibc 2.19,
+the definitions of the nanoseconds components are also defined if
+.B _BSD_SOURCE
+or
+.B _SVID_SOURCE
+is defined.
+If none of the aforementioned macros are defined,
+then the nanosecond values are exposed with names of the form
+.IR st_atimensec .
+.SH NOTES
+The following header also provides this type:
+.IR <ftw.h> .
+.SH SEE ALSO
+.BR stat (2),
+.BR inode (7)
diff --git a/man/man3type/suseconds_t.3type b/man/man3type/suseconds_t.3type
new file mode 100644
index 000000000..7f430e1eb
--- /dev/null
+++ b/man/man3type/suseconds_t.3type
@@ -0,0 +1 @@
+.so man3type/time_t.3type
diff --git a/man/man3type/tcflag_t.3type b/man/man3type/tcflag_t.3type
new file mode 100644
index 000000000..26cfd0171
--- /dev/null
+++ b/man/man3type/tcflag_t.3type
@@ -0,0 +1 @@
+.so man3type/cc_t.3type
diff --git a/man/man3type/time_t.3type b/man/man3type/time_t.3type
new file mode 100644
index 000000000..0dba4afb0
--- /dev/null
+++ b/man/man3type/time_t.3type
@@ -0,0 +1,111 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH time_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+time_t, suseconds_t, useconds_t \- integer time
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <time.h>
+.P
+.BR typedef " /* ... */  " time_t;
+.P
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */  " suseconds_t;
+.BR typedef " /* ... */  " useconds_t;
+.fi
+.SH DESCRIPTION
+.TP
+.I time_t
+Used for time in seconds.
+According to POSIX,
+it is an integer type.
+.\" In POSIX.1-2001, the type was specified as being either an integer
+.\" type or a real-floating type. However, existing implementations
+.\" used an integer type, and POSIX.1-2008 tightened the specification
+.\" to reflect this.
+.TP
+.I suseconds_t
+Used for time in microseconds.
+It is a signed integer type
+capable of storing values at least in the range
+.RB [ \-1 ,
+.BR 1000000 ].
+.TP
+.I useconds_t
+Used for time in microseconds.
+It is an unsigned integer type
+capable of storing values at least in the range
+.RB [ 0 ,
+.BR 1000000 ].
+.SH STANDARDS
+.TP
+.I time_t
+C11, POSIX.1-2008.
+.TP
+.I suseconds_t
+.TQ
+.I useconds_t
+POSIX.1-2008.
+.PD
+.SH HISTORY
+.TP
+.I time_t
+C89, POSIX.1-2001.
+.TP
+.I suseconds_t
+.TQ
+.I useconds_t
+POSIX.1-2001.
+.P
+.I <sched.h>
+defines
+.I time_t
+since POSIX.1-2008.
+.P
+POSIX.1-2001 defined
+.I useconds_t
+in
+.I <unistd.h>
+too.
+.SH NOTES
+On some architectures,
+the width of
+.I time_t
+can be controlled with the feature test macro
+.BR _TIME_BITS .
+See
+.BR feature_test_macros (7).
+.P
+The following headers also provide
+.IR time_t :
+.IR <sched.h> ,
+.IR <sys/msg.h> ,
+.IR <sys/select.h> ,
+.IR <sys/sem.h> ,
+.IR <sys/shm.h> ,
+.IR <sys/stat.h> ,
+.IR <sys/time.h> ,
+.IR <sys/types.h> ,
+and
+.IR <utime.h> .
+.P
+The following headers also provide
+.IR suseconds_t :
+.I <sys/select.h>
+and
+.IR <sys/time.h> .
+.SH SEE ALSO
+.BR stime (2),
+.BR time (2),
+.BR ctime (3),
+.BR difftime (3),
+.BR usleep (3),
+.BR timeval (3type)
diff --git a/man/man3type/timer_t.3type b/man/man3type/timer_t.3type
new file mode 100644
index 000000000..c0b2afa8b
--- /dev/null
+++ b/man/man3type/timer_t.3type
@@ -0,0 +1,34 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH timer_t 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+timer_t \- timer ID
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <sys/types.h>
+.P
+.BR typedef " /* ... */  " timer_t;
+.fi
+.SH DESCRIPTION
+Used for timer ID returned by
+.BR timer_create (2).
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following header also provides
+.IR timer_t :
+.IR <time.h> .
+.SH SEE ALSO
+.BR timer_create (2),
+.BR timer_delete (2),
+.BR timer_getoverrun (2),
+.BR timer_settime (2)
diff --git a/man/man3type/timespec.3type b/man/man3type/timespec.3type
new file mode 100644
index 000000000..7f5c97cd6
--- /dev/null
+++ b/man/man3type/timespec.3type
@@ -0,0 +1,60 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH timespec 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+timespec \- time in seconds and nanoseconds
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <time.h>
+.P
+.B struct timespec {
+.BR "    time_t     tv_sec;" "   /* Seconds */"
+.RB "    /* ... */" "  tv_nsec;" \
+"  /* Nanoseconds [" 0 ", " 999\[aq]999\[aq]999 "] */"
+.B };
+.EE
+.SH DESCRIPTION
+Describes times in seconds and nanoseconds.
+.P
+.I tv_nsec
+is of an implementation-defined signed type
+capable of holding the specified range.
+Under glibc, this is usually
+.IR long ,
+and
+.I long long
+on X32.
+It can be safely down-cast to any concrete 32-bit integer type for processing.
+.SH VERSIONS
+Prior to C23,
+.I tv_nsec
+was
+.IR long .
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following headers also provide this type:
+.IR <aio.h> ,
+.IR <mqueue.h> ,
+.IR <sched.h> ,
+.IR <signal.h> ,
+.IR <sys/select.h> ,
+and
+.IR <sys/stat.h> .
+.SH SEE ALSO
+.BR clock_gettime (2),
+.BR clock_nanosleep (2),
+.BR nanosleep (2),
+.BR timerfd_gettime (2),
+.BR timer_gettime (2),
+.BR time_t (3type),
+.BR timeval (3type)
diff --git a/man/man3type/timeval.3type b/man/man3type/timeval.3type
new file mode 100644
index 000000000..7223c7b09
--- /dev/null
+++ b/man/man3type/timeval.3type
@@ -0,0 +1,43 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH timeval 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+timeval \- time in seconds and microseconds
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <sys/time.h>
+.P
+.B struct timeval {
+.BR "    time_t       tv_sec;" "   /* Seconds */"
+.BR "    suseconds_t  tv_usec;" "  /* Microseconds */"
+.B };
+.EE
+.SH DESCRIPTION
+Describes times in seconds and microseconds.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The following headers also provide this type:
+.IR <sys/resource.h> ,
+.IR <sys/select.h> ,
+and
+.IR <utmpx.h> .
+.SH SEE ALSO
+.BR gettimeofday (2),
+.BR select (2),
+.BR utimes (2),
+.BR adjtime (3),
+.BR futimes (3),
+.BR timeradd (3),
+.BR suseconds_t (3type),
+.BR time_t (3type),
+.BR timespec (3type)
diff --git a/man/man3type/tm.3type b/man/man3type/tm.3type
new file mode 100644
index 000000000..5d5b28658
--- /dev/null
+++ b/man/man3type/tm.3type
@@ -0,0 +1,112 @@
+.\" Copyright (c) 2022 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH tm 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+tm \- broken-down time
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.EX
+.B #include <time.h>
+.P
+.B struct tm {
+.BR "    int         tm_sec;" "    /* Seconds          [" 0 ", " 60 "] */"
+.BR "    int         tm_min;" "    /* Minutes          [" 0 ", " 59 "] */"
+.BR "    int         tm_hour;" "   /* Hour             [" 0 ", " 23 "] */"
+.BR "    int         tm_mday;" "   /* Day of the month [" 1 ", " 31 "] */"
+.BR "    int         tm_mon;" \
+"    /* Month            [" 0 ", " 11 "]  (January = " 0 ") */"
+.BR "    int         tm_year;" "   /* Year minus " 1900 " */"
+.BR "    int         tm_wday;" \
+"   /* Day of the week  [" 0 ", " 6 "]   (Sunday = " 0 ") */"
+.BR "    int         tm_yday;" \
+"   /* Day of the year  [" 0 ", " 365 "] (Jan/01 = " 0 ") */"
+.BR "    int         tm_isdst;" "  /* Daylight savings flag */"
+.P
+.BR "    long        tm_gmtoff;" " /* Seconds East of UTC */"
+.BR "    const char *tm_zone;" "   /* Timezone abbreviation */"
+.B };
+.EE
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.IR tm_gmtoff ,
+.IR tm_zone :
+.nf
+.\" Guarded with __USE_MISC:
+    Since glibc 2.20:
+        _DEFAULT_SOURCE
+    glibc 2.20 and earlier:
+        _BSD_SOURCE
+.fi
+.SH DESCRIPTION
+Describes time, broken down into distinct components.
+.P
+.I tm_isdst
+describes whether daylight saving time is in effect at the time described.
+The value is positive if daylight saving time is in effect,
+zero if it is not,
+and negative if the information is not available.
+.P
+.I tm_gmtoff
+is the difference, in seconds,
+of the timezone represented by this broken-down time and UTC
+(this is the additive inverse of
+.BR timezone (3)).
+.P
+.I tm_zone
+is the equivalent of
+.BR tzname (3)
+for the timezone represented by this broken-down time.
+.SH VERSIONS
+In C90,
+.I tm_sec
+could represent values in the range
+.RB [ 0 ", " 61 ],
+which could represent a double leap second.
+UTC doesn't permit double leap seconds,
+so it was limited to
+.B 60
+in C99.
+.P
+.BR timezone (3),
+as a variable, is an XSI extension: some systems provide the V7-compatible
+.\" FreeBSD
+.BR timezone (3)
+function.
+The
+.I tm_gmtoff
+field provides an alternative (with the opposite sign) for those systems.
+.P
+.I tm_zone
+points to static storage and may be overridden on subsequent calls to
+.BR localtime (3)
+and similar functions (however, this never happens under glibc).
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.P
+.I tm_gmtoff
+and
+.I tm_zone
+originate from 4.3BSD-Tahoe (where
+.I tm_zone
+is a
+.IR "char *" ).
+.SH NOTES
+.I tm_sec
+can represent a leap second with the value
+.BR 60 .
+.SH SEE ALSO
+.BR ctime (3),
+.BR strftime (3),
+.BR strptime (3),
+.BR time (7)
diff --git a/man/man3type/uid_t.3type b/man/man3type/uid_t.3type
new file mode 100644
index 000000000..52bae7406
--- /dev/null
+++ b/man/man3type/uid_t.3type
@@ -0,0 +1 @@
+.so man3type/id_t.3type
diff --git a/man/man3type/uint16_t.3type b/man/man3type/uint16_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/uint16_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/uint32_t.3type b/man/man3type/uint32_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/uint32_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/uint64_t.3type b/man/man3type/uint64_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/uint64_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/uint8_t.3type b/man/man3type/uint8_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/uint8_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/uintN_t.3type b/man/man3type/uintN_t.3type
new file mode 100644
index 000000000..a0d1a82b8
--- /dev/null
+++ b/man/man3type/uintN_t.3type
@@ -0,0 +1 @@
+.so man3type/intN_t.3type
diff --git a/man/man3type/uintmax_t.3type b/man/man3type/uintmax_t.3type
new file mode 100644
index 000000000..497d4ace1
--- /dev/null
+++ b/man/man3type/uintmax_t.3type
@@ -0,0 +1 @@
+.so man3type/intmax_t.3type
diff --git a/man/man3type/uintptr_t.3type b/man/man3type/uintptr_t.3type
new file mode 100644
index 000000000..6a55bc9be
--- /dev/null
+++ b/man/man3type/uintptr_t.3type
@@ -0,0 +1 @@
+.so man3type/intptr_t.3type
diff --git a/man/man3type/useconds_t.3type b/man/man3type/useconds_t.3type
new file mode 100644
index 000000000..7f430e1eb
--- /dev/null
+++ b/man/man3type/useconds_t.3type
@@ -0,0 +1 @@
+.so man3type/time_t.3type
diff --git a/man/man3type/va_list.3type b/man/man3type/va_list.3type
new file mode 100644
index 000000000..800f80b43
--- /dev/null
+++ b/man/man3type/va_list.3type
@@ -0,0 +1,44 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH va_list 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+va_list \- variable argument list
+.SH LIBRARY
+Standard C library
+.RI ( libc )
+.SH SYNOPSIS
+.nf
+.B #include <stdarg.h>
+.P
+.BR typedef " /* ... */  " va_list;
+.fi
+.SH DESCRIPTION
+Used by functions with a varying number of arguments of varying types.
+The function must declare an object of type
+.I va_list
+which is used by the macros
+.BR va_start (3),
+.BR va_arg (3),
+.BR va_copy (3),
+and
+.BR va_end (3)
+to traverse the list of arguments.
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH NOTES
+The following headers also provide
+.IR va_list :
+.I <stdio.h>
+and
+.IR <wchar.h> .
+.SH SEE ALSO
+.BR va_start (3),
+.BR va_arg (3),
+.BR va_copy (3),
+.BR va_end (3)
diff --git a/man/man3type/void.3type b/man/man3type/void.3type
new file mode 100644
index 000000000..91d458ff7
--- /dev/null
+++ b/man/man3type/void.3type
@@ -0,0 +1,76 @@
+.\" Copyright (c) 2020-2022 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH void 3type (date) "Linux man-pages (unreleased)"
+.SH NAME
+void \- abstract type
+.SH SYNOPSIS
+.nf
+.B void *
+.fi
+.SH DESCRIPTION
+A pointer to any object type may be converted to a pointer to
+.I void
+and back.
+POSIX further requires that any pointer,
+including pointers to functions,
+may be converted to a pointer to
+.I void
+and back.
+.P
+Conversions from and to any other pointer type are done implicitly,
+not requiring casts at all.
+Note that this feature prevents any kind of type checking:
+the programmer should be careful not to convert a
+.I void *
+value to a type incompatible to that of the underlying data,
+because that would result in undefined behavior.
+.P
+This type is useful in function parameters and return value
+to allow passing values of any type.
+The function will typically use some mechanism to know
+the real type of the data being passed via a pointer to
+.IR void .
+.P
+A value of this type can't be dereferenced,
+as it would give a value of type
+.IR void ,
+which is not possible.
+Likewise, pointer arithmetic is not possible with this type.
+However, in GNU C, pointer arithmetic is allowed
+as an extension to the standard;
+this is done by treating the size of a
+.I void
+or of a function as 1.
+A consequence of this is that
+.I sizeof
+is also allowed on
+.I void
+and on function types, and returns 1.
+.SS Use with printf(3) and scanf(3)
+The conversion specifier for
+.I void *
+for the
+.BR printf (3)
+and the
+.BR scanf (3)
+families of functions is
+.BR p .
+.SH VERSIONS
+The POSIX requirement about compatibility between
+.I void *
+and function pointers was added in
+POSIX.1-2008 Technical Corrigendum 1 (2013).
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+C89, POSIX.1-2001.
+.SH SEE ALSO
+.BR malloc (3),
+.BR memcmp (3),
+.BR memcpy (3),
+.BR memset (3),
+.BR intptr_t (3type)
diff --git a/man/man4/cciss.4 b/man/man4/cciss.4
new file mode 100644
index 000000000..a3fadb5d1
--- /dev/null
+++ b/man/man4/cciss.4
@@ -0,0 +1,385 @@
+'\" t
+.\" Copyright (C) 2011, Hewlett-Packard Development Company, L.P.
+.\" Written by Stephen M. Cameron <scameron@beardog.cce.hp.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.\"
+.\" shorthand for double quote that works everywhere.
+.ds q \N'34'
+.TH cciss 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cciss \- HP Smart Array block driver
+.SH SYNOPSIS
+.nf
+modprobe cciss [ cciss_allow_hpsa=1 ]
+.fi
+.SH DESCRIPTION
+.\" commit 253d2464df446456c0bba5ed4137a7be0b278aa8
+.BR Note :
+This obsolete driver was removed in Linux 4.14,
+as it is superseded by the
+.BR hpsa (4)
+driver in newer kernels.
+.P
+.B cciss
+is a block driver for older HP Smart Array RAID controllers.
+.SS Options
+.IR "cciss_allow_hpsa=1" :
+This option prevents the
+.B cciss
+driver from attempting to drive any controllers that the
+.BR hpsa (4)
+driver is capable of controlling, which is to say, the
+.B cciss
+driver is restricted by this option to the following controllers:
+.P
+.nf
+    Smart Array 5300
+    Smart Array 5i
+    Smart Array 532
+    Smart Array 5312
+    Smart Array 641
+    Smart Array 642
+    Smart Array 6400
+    Smart Array 6400 EM
+    Smart Array 6i
+    Smart Array P600
+    Smart Array P400i
+    Smart Array E200i
+    Smart Array E200
+    Smart Array E200i
+    Smart Array E200i
+    Smart Array E200i
+    Smart Array E500
+.fi
+.SS Supported hardware
+The
+.B cciss
+driver supports the following Smart Array boards:
+.P
+.nf
+    Smart Array 5300
+    Smart Array 5i
+    Smart Array 532
+    Smart Array 5312
+    Smart Array 641
+    Smart Array 642
+    Smart Array 6400
+    Smart Array 6400 U320 Expansion Module
+    Smart Array 6i
+    Smart Array P600
+    Smart Array P800
+    Smart Array E400
+    Smart Array P400i
+    Smart Array E200
+    Smart Array E200i
+    Smart Array E500
+    Smart Array P700m
+    Smart Array P212
+    Smart Array P410
+    Smart Array P410i
+    Smart Array P411
+    Smart Array P812
+    Smart Array P712m
+    Smart Array P711m
+.fi
+.SS Configuration details
+To configure HP Smart Array controllers,
+use the HP Array Configuration Utility
+(either
+.BR hpacuxe (8)
+or
+.BR hpacucli (8))
+or the Offline ROM-based Configuration Utility (ORCA)
+run from the Smart Array's option ROM at boot time.
+.SH FILES
+.SS Device nodes
+The device naming scheme is as follows:
+.P
+Major numbers:
+.IP
+.TS
+r r.
+104	cciss0
+105	cciss1
+106	cciss2
+105	cciss3
+108	cciss4
+109	cciss5
+110	cciss6
+111	cciss7
+.TE
+.P
+Minor numbers:
+.P
+.EX
+    b7 b6 b5 b4 b3 b2 b1 b0
+    |\-\-\-\-+\-\-\-\-| |\-\-\-\-+\-\-\-\-|
+         |           |
+         |           +\-\-\-\-\-\-\-\- Partition ID (0=wholedev, 1\-15 partition)
+         |
+         +\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- Logical Volume number
+.EE
+.P
+The device naming scheme is:
+.TS
+li l.
+/dev/cciss/c0d0	Controller 0, disk 0, whole device
+/dev/cciss/c0d0p1	Controller 0, disk 0, partition 1
+/dev/cciss/c0d0p2	Controller 0, disk 0, partition 2
+/dev/cciss/c0d0p3	Controller 0, disk 0, partition 3
+\&
+/dev/cciss/c1d1	Controller 1, disk 1, whole device
+/dev/cciss/c1d1p1	Controller 1, disk 1, partition 1
+/dev/cciss/c1d1p2	Controller 1, disk 1, partition 2
+/dev/cciss/c1d1p3	Controller 1, disk 1, partition 3
+.TE
+.SS Files in /proc
+The files
+.I /proc/driver/cciss/cciss[0\-9]+
+contain information about
+the configuration of each controller.
+For example:
+.P
+.in +4n
+.EX
+$ \fBcd /proc/driver/cciss\fP
+$ \fBls \-l\fP
+total 0
+-rw\-r\-\-r\-\- 1 root root 0 2010\-09\-10 10:38 cciss0
+-rw\-r\-\-r\-\- 1 root root 0 2010\-09\-10 10:38 cciss1
+-rw\-r\-\-r\-\- 1 root root 0 2010\-09\-10 10:38 cciss2
+$ \fBcat cciss2\fP
+cciss2: HP Smart Array P800 Controller
+Board ID: 0x3223103c
+Firmware Version: 7.14
+IRQ: 16
+Logical drives: 1
+Current Q depth: 0
+Current # commands on controller: 0
+Max Q depth since init: 1
+Max # commands on controller since init: 2
+Max SG entries since init: 32
+Sequential access devices: 0
+\&
+cciss/c2d0:   36.38GB       RAID 0
+.EE
+.in
+.\"
+.SS Files in /sys
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /model
+Displays the SCSI INQUIRY page 0 model for logical drive
+.I Y
+of controller
+.IR X .
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /rev
+Displays the SCSI INQUIRY page 0 revision for logical drive
+.I Y
+of controller
+.IR X .
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /unique_id
+Displays the SCSI INQUIRY page 83 serial number for logical drive
+.I Y
+of controller
+.IR X .
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /vendor
+Displays the SCSI INQUIRY page 0 vendor for logical drive
+.I Y
+of controller
+.IR X .
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /block:cciss!c X d Y
+A symbolic link to
+.IR /sys/block/cciss!c X d Y.
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /rescan
+When this file is written to, the driver rescans the controller
+to discover any new, removed, or modified logical drives.
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /resettable
+A value of 1 displayed in this file indicates that
+the "reset_devices=1" kernel parameter (used by
+.BR kdump )
+is honored by this controller.
+A value of 0 indicates that the
+"reset_devices=1" kernel parameter will not be honored.
+Some models of Smart Array are not able to honor this parameter.
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /lunid
+Displays the 8-byte LUN ID used to address logical drive
+.I Y
+of controller
+.IR X .
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /raid_level
+Displays the RAID level of logical drive
+.I Y
+of controller
+.IR X .
+.TP
+.IR /sys/bus/pci/devices/ dev /cciss X /c X d Y /usage_count
+Displays the usage count (number of opens) of logical drive
+.I Y
+of controller
+.IR X .
+.SS SCSI tape drive and medium changer support
+SCSI sequential access devices and medium changer devices are supported and
+appropriate device nodes are automatically created (e.g.,
+.IR /dev/st0 ,
+.IR /dev/st1 ,
+etc.; see
+.BR st (4)
+for more details.)
+You must enable "SCSI tape drive support for Smart Array 5xxx" and
+"SCSI support" in your kernel configuration to be able to use SCSI
+tape drives with your Smart Array 5xxx controller.
+.P
+Additionally, note that the driver will not engage the SCSI core at
+init time.
+The driver must be directed to dynamically engage the SCSI core via the
+.I /proc
+filesystem entry,
+which the "block" side of the driver creates as
+.I /proc/driver/cciss/cciss*
+at run time.
+This is because at driver init time,
+the SCSI core may not yet be initialized (because the driver is a block
+driver) and attempting to register it with the SCSI core in such a case
+would cause a hang.
+This is best done via an initialization script
+(typically in
+.IR /etc/init.d ,
+but could vary depending on distribution).
+For example:
+.P
+.in +4n
+.EX
+for x in /proc/driver/cciss/cciss[0\-9]*
+do
+    echo "engage scsi" > $x
+done
+.EE
+.in
+.P
+Once the SCSI core is engaged by the driver, it cannot be disengaged
+(except by unloading the driver, if it happens to be linked as a module.)
+.P
+Note also that if no sequential access devices or medium changers are
+detected, the SCSI core will not be engaged by the action of the above
+script.
+.SS Hot plug support for SCSI tape drives
+Hot plugging of SCSI tape drives is supported, with some caveats.
+The
+.B cciss
+driver must be informed that changes to the SCSI bus
+have been made.
+This may be done via the
+.I /proc
+filesystem.
+For example:
+.IP
+echo "rescan" > /proc/scsi/cciss0/1
+.P
+This causes the driver to:
+.RS
+.IP (1) 5
+query the adapter about changes to the
+physical SCSI buses and/or fiber channel arbitrated loop, and
+.IP (2)
+make note of any new or removed sequential access devices
+or medium changers.
+.RE
+.P
+The driver will output messages indicating which
+devices have been added or removed and the controller, bus, target, and
+lun used to address each device.
+The driver then notifies the SCSI midlayer
+of these changes.
+.P
+Note that the naming convention of the
+.I /proc
+filesystem entries
+contains a number in addition to the driver name
+(e.g., "cciss0"
+instead of just "cciss", which you might expect).
+.P
+Note:
+.I Only
+sequential access devices and medium changers are presented
+as SCSI devices to the SCSI midlayer by the
+.B cciss
+driver.
+Specifically, physical SCSI disk drives are
+.I not
+presented to the SCSI midlayer.
+The only disk devices that are presented to the kernel are logical
+drives that the array controller constructs from regions on
+the physical drives.
+The logical drives are presented to the block layer
+(not to the SCSI midlayer).
+It is important for the driver to prevent the kernel from accessing the
+physical drives directly, since these drives are used by the array
+controller to construct the logical drives.
+.SS SCSI error handling for tape drives and medium changers
+The Linux SCSI midlayer provides an error-handling protocol that
+is initiated whenever a SCSI command fails to complete within a
+certain amount of time (which can vary depending on the command).
+The
+.B cciss
+driver participates in this protocol to some extent.
+The normal protocol is a four-step process:
+.IP (1) 5
+First, the device is told to abort the command.
+.IP (2)
+If that doesn't work, the device is reset.
+.IP (3)
+If that doesn't work, the SCSI bus is reset.
+.IP (4)
+If that doesn't work, the host bus adapter is reset.
+.P
+The
+.B cciss
+driver is a block
+driver as well as a SCSI driver and only the tape drives and medium
+changers are presented to the SCSI midlayer.
+Furthermore, unlike more
+straightforward SCSI drivers, disk I/O continues through the block
+side during the SCSI error-recovery process.
+Therefore, the
+.B cciss
+driver implements only the first two of these actions,
+aborting the command, and resetting the device.
+Note also that most tape drives will not oblige
+in aborting commands, and sometimes it appears they will not even
+obey a reset command, though in most circumstances they will.
+If the command cannot be aborted and the device cannot be
+reset, the device will be set offline.
+.P
+In the event that the error-handling code is triggered and a tape drive is
+successfully reset or the tardy command is successfully aborted, the
+tape drive may still not allow I/O to continue until some command
+is issued that positions the tape to a known position.
+Typically you must rewind the tape (by issuing
+.I "mt \-f /dev/st0 rewind"
+for example) before I/O can proceed again to a tape drive that was reset.
+.SH SEE ALSO
+.BR hpsa (4),
+.BR cciss_vol_status (8),
+.BR hpacucli (8),
+.BR hpacuxe (8)
+.P
+.UR http://cciss.sf.net
+.UE ,
+and
+.I Documentation/blockdev/cciss.txt
+and
+.I Documentation/ABI/testing/sysfs\-bus\-pci\-devices\-cciss
+in the Linux kernel source tree
+.\" .SH AUTHORS
+.\" Don Brace, Steve Cameron, Chase Maupin, Mike Miller, Michael Ni,
+.\" Charles White, Francis Wiran
+.\" and probably some other people.
diff --git a/man/man4/console_codes.4 b/man/man4/console_codes.4
new file mode 100644
index 000000000..5d4af9cf9
--- /dev/null
+++ b/man/man4/console_codes.4
@@ -0,0 +1,811 @@
+'\" t
+.\" Copyright (c) 1996 Andries Brouwer <aeb@cwi.nl>, Mon Oct 31 22:13:04 1996
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" This is combined from many sources.
+.\" For Linux, the definitive source is of course console.c.
+.\" About vt100-like escape sequences in general there are
+.\" the ISO/IEC 6429 and ISO/IEC 2022 norms, the descriptions of
+.\" an actual vt100, and the xterm docs (ctlseqs.ms).
+.\" Substantial portions of this text are derived from a write-up
+.\" by Eric S. Raymond <esr@thyrsus.com>.
+.\"
+.\" Tiny correction, aeb, 961107.
+.\"
+.\" 2006-05-27, Several corrections - Thomas E. Dickey
+.\"
+.TH console_codes 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+console_codes \- Linux console escape and control sequences
+.SH DESCRIPTION
+The Linux console implements a large subset of
+the VT102 and ECMA-48 / ISO/IEC\~6429 / ANSI X3.64 terminal controls,
+plus certain private-mode sequences
+for changing the color palette, character-set mapping, and so on.
+In the tabular descriptions below, the second column gives ECMA-48 or DEC
+mnemonics (the latter if prefixed with DEC) for the given function.
+Sequences without a mnemonic are neither ECMA-48 nor VT102.
+.P
+After all the normal output processing has been done, and a
+stream of characters arrives at the console driver for actual
+printing, the first thing that happens is a translation from
+the code used for processing to the code used for printing.
+.P
+If the console is in UTF-8 mode, then the incoming bytes are
+first assembled into 16-bit Unicode codes.
+Otherwise, each byte is transformed according to the current mapping table
+(which translates it to a Unicode value).
+See the \fBCharacter Sets\fP section below for discussion.
+.P
+In the normal case, the Unicode value is converted to a font index,
+and this is stored in video memory, so that the corresponding glyph
+(as found in video ROM) appears on the screen.
+Note that the use of Unicode (and the design of the PC hardware)
+allows us to use 512 different glyphs simultaneously.
+.P
+If the current Unicode value is a control character, or we are
+currently processing an escape sequence, the value will treated
+specially.
+Instead of being turned into a font index and rendered as
+a glyph, it may trigger cursor movement or other control functions.
+See the \fBLinux Console Controls\fP section below for discussion.
+.P
+It is generally not good practice to hard-wire terminal controls into
+programs.
+Linux supports a
+.BR terminfo (5)
+database of terminal capabilities.
+Rather than emitting console escape sequences by hand, you will almost
+always want to use a terminfo-aware screen library or utility such as
+.BR ncurses (3),
+.BR tput (1),
+or
+.BR reset (1).
+.SS Linux console controls
+This section describes all the control characters and escape sequences
+that invoke special functions (i.e., anything other than writing a
+glyph at the current cursor location) on the Linux console.
+.P
+.B "Control characters"
+.P
+A character is a control character if (before transformation
+according to the mapping table) it has one of the 14 codes
+00 (NUL), 07 (BEL), 08 (BS), 09 (HT), 0a (LF), 0b (VT),
+0c (FF), 0d (CR), 0e (SO), 0f (SI), 18 (CAN), 1a (SUB),
+1b (ESC), 7f (DEL).
+One can set a "display control characters" mode (see below),
+and allow 07, 09, 0b, 18, 1a, 7f to be displayed as glyphs.
+On the other hand, in UTF-8 mode all codes 00\[en]1f are regarded
+as control characters, regardless of any "display control characters"
+mode.
+.P
+If we have a control character, it is acted upon immediately
+and then discarded (even in the middle of an escape sequence)
+and the escape sequence continues with the next character.
+(However, ESC starts a new escape sequence, possibly aborting a previous
+unfinished one, and CAN and SUB abort any escape sequence.)
+The recognized control characters are BEL, BS, HT, LF, VT, FF,
+CR, SO, SI, CAN, SUB, ESC, DEL, CSI.
+They do what one would expect:
+.TP
+BEL (0x07, \fB\[ha]G\fP)
+beeps;
+.TP
+BS (0x08, \fB\[ha]H\fP)
+backspaces one column
+(but not past the beginning of the line);
+.TP
+HT (0x09, \fB\[ha]I\fP)
+goes to the next tab stop or to the end of the line
+if there is no earlier tab stop;
+.TP
+LF (0x0A, \fB\[ha]J\fP)
+.TQ
+VT (0x0B, \fB\[ha]K\fP)
+.TQ
+FF (0x0C, \fB\[ha]L\fP)
+all give a linefeed,
+and if LF/NL (new-line mode) is set also a carriage return;
+.TP
+CR (0x0D, \fB\[ha]M\fP)
+gives a carriage return;
+.TP
+SO (0x0E, \fB\[ha]N\fP)
+activates the G1 character set;
+.TP
+SI (0x0F, \fB\[ha]O\fP)
+activates the G0 character set;
+.TP
+CAN (0x18, \fB\[ha]X\fP)
+.TQ
+SUB (0x1A, \fB\[ha]Z\fP)
+abort escape sequences;
+.TP
+ESC (0x1B, \fB\[ha][\fP)
+starts an escape sequence;
+.TP
+DEL (0x7F)
+is ignored;
+.TP
+CSI (0x9B)
+is equivalent to ESC [.
+.P
+.B "ESC- but not CSI-sequences"
+.ad l
+.TS
+l l lx.
+ESC c	RIS	Reset.
+ESC D	IND	Linefeed.
+ESC E	NEL	Newline.
+ESC H	HTS	Set tab stop at current column.
+ESC M	RI	Reverse linefeed.
+ESC Z	DECID	T{
+DEC private identification. The kernel
+returns the string  ESC [ ? 6 c, claiming
+that it is a VT102.
+T}
+ESC 7	DECSC	T{
+Save current state (cursor coordinates,
+attributes, character sets pointed at by G0, G1).
+T}
+ESC 8	DECRC	T{
+Restore state most recently saved by ESC 7.
+T}
+ESC %		Start sequence selecting character set
+ESC % @		\0\0\0Select default (ISO/IEC\~646 / ISO/IEC\~8859-1)
+ESC % G		\0\0\0Select UTF-8
+ESC % 8		\0\0\0Select UTF-8 (obsolete)
+ESC # 8	DECALN	T{
+DEC screen alignment test \- fill screen with E's.
+T}
+ESC (		T{
+Start sequence defining G0 character set
+(followed by one of B, 0, U, K, as below)
+T}
+ESC ( B		T{
+Select default (ISO/IEC\~8859-1 mapping).
+T}
+ESC ( 0		T{
+Select VT100 graphics mapping.
+T}
+ESC ( U		T{
+Select null mapping \- straight to character ROM.
+T}
+ESC ( K		T{
+Select user mapping \- the map that is loaded by the utility \fBmapscrn\fP(8).
+T}
+ESC )		T{
+Start sequence defining G1 (followed by one of B, 0, U, K, as above).
+T}
+ESC >	DECPNM	Set numeric keypad mode
+ESC =	DECPAM	Set application keypad mode
+ESC ]	OSC	T{
+Operating System Command prefix.
+T}
+ESC ] R		Reset palette.
+ESC ] P		T{
+Set palette, with parameter given in 7 hexadecimal digits \fInrrggbb\fP after
+the final P. Here \fIn\fP is the color (0\[en]15), and \fIrrggbb\fP indicates
+the red/green/blue values (0\[en]255).
+T}
+.TE
+.ad
+.P
+.B "ECMA-48 CSI sequences"
+.P
+CSI (or ESC [) is followed by a sequence of parameters,
+at most NPAR (16), that are decimal numbers separated by
+semicolons.
+An empty or absent parameter is taken to be 0.
+The sequence of parameters may be preceded by a single question mark.
+.P
+However, after CSI [ (or ESC [ [) a single character is read
+and this entire sequence is ignored.
+(The idea is to ignore an echoed function key.)
+.P
+The action of a CSI sequence is determined by its final character.
+.ad l
+.TS
+l l lx.
+@	ICH	T{
+Insert the indicated # of blank characters.
+T}
+A	CUU	T{
+Move cursor up the indicated # of rows.
+T}
+B	CUD	T{
+Move cursor down the indicated # of rows.
+T}
+C	CUF	T{
+Move cursor right the indicated # of columns.
+T}
+D	CUB	T{
+Move cursor left the indicated # of columns.
+T}
+E	CNL	T{
+Move cursor down the indicated # of rows, to column 1.
+T}
+F	CPL	T{
+Move cursor up the indicated # of rows, to column 1.
+T}
+G	CHA	T{
+Move cursor to indicated column in current row.
+T}
+H	CUP	T{
+Move cursor to the indicated row, column (origin at 1,1).
+T}
+J	ED	T{
+Erase display (default: from cursor to end of display).
+T}
+		T{
+ESC [ 1 J: erase from start to cursor.
+T}
+		T{
+ESC [ 2 J: erase whole display.
+T}
+		T{
+ESC [ 3 J: erase whole display including scroll-back
+buffer (since Linux 3.0).
+T}
+.\" ESC [ 3 J: commit f8df13e0a901fe55631fed66562369b4dba40f8b
+K	EL	T{
+Erase line (default: from cursor to end of line).
+T}
+		T{
+ESC [ 1 K: erase from start of line to cursor.
+T}
+		T{
+ESC [ 2 K: erase whole line.
+T}
+L	IL	T{
+Insert the indicated # of blank lines.
+T}
+M	DL	T{
+Delete the indicated # of lines.
+T}
+P	DCH	T{
+Delete the indicated # of characters on current line.
+T}
+X	ECH	T{
+Erase the indicated # of characters on current line.
+T}
+a	HPR	T{
+Move cursor right the indicated # of columns.
+T}
+c	DA	T{
+Answer ESC [ ? 6 c: "I am a VT102".
+T}
+d	VPA	T{
+Move cursor to the indicated row, current column.
+T}
+e	VPR	T{
+Move cursor down the indicated # of rows.
+T}
+f	HVP	T{
+Move cursor to the indicated row, column.
+T}
+g	TBC	T{
+Without parameter: clear tab stop at current position.
+T}
+		T{
+ESC [ 3 g: delete all tab stops.
+T}
+h	SM	Set Mode (see below).
+l	RM	Reset Mode (see below).
+m	SGR	Set attributes (see below).
+n	DSR	Status report (see below).
+q	DECLL	Set keyboard LEDs.
+		ESC [ 0 q: clear all LEDs
+		ESC [ 1 q: set Scroll Lock LED
+		ESC [ 2 q: set Num Lock LED
+		ESC [ 3 q: set Caps Lock LED
+r	DECSTBM	T{
+Set scrolling region; parameters are top and bottom row.
+T}
+s	?	Save cursor location.
+u	?	Restore cursor location.
+\`	HPA	T{
+Move cursor to indicated column in current row.
+T}
+.TE
+.ad
+.P
+.B ECMA-48 Select Graphic Rendition
+.P
+The ECMA-48 SGR sequence ESC [ \fIparameters\fP m sets display
+attributes.
+Several attributes can be set in the same sequence, separated by
+semicolons.
+An empty parameter (between semicolons or string initiator or
+terminator) is interpreted as a zero.
+.ad l
+.TS
+l lx.
+param	result
+0	T{
+reset all attributes to their defaults
+T}
+1	set bold
+2	T{
+set half-bright (simulated with color on a color display)
+T}
+3	set italic (since Linux 2.6.22; simulated with color on a color display)
+4	T{
+set underscore (simulated with color on a color display)
+(the colors used to simulate dim or underline are set
+using ESC ] ...)
+T}
+5	set blink
+7	set reverse video
+10	T{
+reset selected mapping, display control flag,
+and toggle meta flag (ECMA-48 says "primary font").
+T}
+11	T{
+select null mapping, set display control flag,
+reset toggle meta flag (ECMA-48 says "first alternate font").
+T}
+12	T{
+select null mapping, set display control flag,
+set toggle meta flag (ECMA-48 says "second alternate font").
+The toggle meta flag
+causes the high bit of a byte to be toggled
+before the mapping table translation is done.
+T}
+21	T{
+set underline; before Linux 4.17, this value
+set normal intensity (as is done in many other terminals)
+T}
+22	set normal intensity
+23	italic off (since Linux 2.6.22)
+24	underline off
+25	blink off
+27	reverse video off
+30	set black foreground
+31	set red foreground
+32	set green foreground
+33	set brown foreground
+34	set blue foreground
+35	set magenta foreground
+36	set cyan foreground
+37	set white foreground
+38	T{
+256/24-bit foreground color follows, shoehorned into 16 basic colors
+(before Linux 3.16: set underscore on, set default foreground color)
+T}
+39	T{
+set default foreground color
+(before Linux 3.16: set underscore off, set default foreground color)
+T}
+40	set black background
+41	set red background
+42	set green background
+43	set brown background
+44	set blue background
+45	set magenta background
+46	set cyan background
+47	set white background
+48	T{
+256/24-bit background color follows, shoehorned into 8 basic colors
+T}
+49	set default background color
+90..97	T{
+set foreground to bright versions of 30..37
+T}
+100..107	T{
+set background, same as 40..47 (bright not supported)
+T}
+.TE
+.ad
+.P
+Commands 38 and 48 require further arguments:
+.TS
+l lx.
+;5;x	T{
+256 color: values 0..15 are IBGR (black, red, green, ... white),
+16..231 a 6x6x6 color cube, 232..255 a grayscale ramp
+T}
+;2;r;g;b	T{
+24-bit color, r/g/b components are in the range 0..255
+T}
+.TE
+.P
+.B ECMA-48 Mode Switches
+.TP
+ESC [ 3 h
+DECCRM (default off): Display control chars.
+.TP
+ESC [ 4 h
+DECIM (default off): Set insert mode.
+.TP
+ESC [ 20 h
+LF/NL (default off): Automatically follow echo of LF, VT, or FF with CR.
+.\"
+.P
+.B ECMA-48 Status Report Commands
+.\"
+.TP
+ESC [ 5 n
+Device status report (DSR): Answer is ESC [ 0 n (Terminal OK).
+.TP
+ESC [ 6 n
+Cursor position report (CPR): Answer is ESC [ \fIy\fP ; \fIx\fP R,
+where \fIx,y\fP is the cursor location.
+.\"
+.P
+.B DEC Private Mode (DECSET/DECRST) sequences
+.P
+.\"
+These are not described in ECMA-48.
+We list the Set Mode sequences;
+the Reset Mode sequences are obtained by replacing the final \[aq]h\[aq]
+by \[aq]l\[aq].
+.TP
+ESC [ ? 1 h
+DECCKM (default off): When set, the cursor keys send an ESC O prefix,
+rather than ESC [.
+.TP
+ESC [ ? 3 h
+DECCOLM (default off = 80 columns): 80/132 col mode switch.
+The driver sources note that this alone does not suffice; some user-mode
+utility such as
+.BR resizecons (8)
+has to change the hardware registers on the console video card.
+.TP
+ESC [ ? 5 h
+DECSCNM (default off): Set reverse-video mode.
+.TP
+ESC [ ? 6 h
+DECOM (default off): When set, cursor addressing is relative to
+the upper left corner of the scrolling region.
+.TP
+ESC [ ? 7 h
+DECAWM (default on): Set autowrap on.
+In this mode, a graphic
+character emitted after column 80 (or column 132 of DECCOLM is on)
+forces a wrap to the beginning of the following line first.
+.TP
+ESC [ ? 8 h
+DECARM (default on): Set keyboard autorepeat on.
+.TP
+ESC [ ? 9 h
+X10 Mouse Reporting (default off): Set reporting mode to 1 (or reset to
+0)\[em]see below.
+.TP
+ESC [ ? 25 h
+DECTECM (default on): Make cursor visible.
+.TP
+ESC [ ? 1000 h
+X11 Mouse Reporting (default off): Set reporting mode to 2 (or reset
+to 0)\[em]see below.
+.\"
+.P
+.B Linux Console Private CSI Sequences
+.P
+.\"
+The following sequences are neither ECMA-48 nor native VT102.
+They are native to the Linux console driver.
+Colors are in SGR parameters:
+0 = black, 1 = red, 2 = green, 3 = brown, 4 = blue, 5 = magenta, 6 =
+cyan, 7 = white; 8\[en]15 = bright versions of 0\[en]7.
+.TS
+l lx.
+ESC [ 1 ; \fIn\fP ]	T{
+Set color \fIn\fP as the underline color.
+T}
+ESC [ 2 ; \fIn\fP ]	T{
+Set color \fIn\fP as the dim color.
+T}
+ESC [ 8 ]       	T{
+Make the current color pair the default attributes.
+T}
+ESC [ 9 ; \fIn\fP ]	T{
+Set screen blank timeout to \fIn\fP minutes.
+T}
+ESC [ 10 ; \fIn\fP ]	T{
+Set bell frequency in Hz.
+T}
+ESC [ 11 ; \fIn\fP ]	T{
+Set bell duration in msec.
+T}
+ESC [ 12 ; \fIn\fP ]	T{
+Bring specified console to the front.
+T}
+ESC [ 13 ]      	T{
+Unblank the screen.
+T}
+ESC [ 14 ; \fIn\fP ]   	T{
+Set the VESA powerdown interval in minutes.
+T}
+ESC [ 15 ]	T{
+Bring the previous console to the front
+(since Linux 2.6.0).
+T}
+ESC [ 16 ; \fIn\fP ]	T{
+Set the cursor blink interval in milliseconds
+(since Linux 4.2).
+T}
+.\" commit bd63364caa8df38bad2b25b11b2a1b849475cce5
+.TE
+.SS Character sets
+The kernel knows about 4 translations of bytes into console-screen
+symbols.
+The four tables are: a) Latin1 \-> PC,
+b) VT100 graphics \-> PC, c) PC \-> PC, d) user-defined.
+.P
+There are two character sets, called G0 and G1, and one of them
+is the current character set.
+(Initially G0.)
+Typing \fB\[ha]N\fP causes G1 to become current,
+\fB\[ha]O\fP causes G0 to become current.
+.P
+These variables G0 and G1 point at a translation table, and can be
+changed by the user.
+Initially they point at tables a) and b), respectively.
+The sequences ESC ( B and ESC ( 0 and ESC ( U and ESC ( K cause G0 to
+point at translation table a), b), c), and d), respectively.
+The sequences ESC ) B and ESC ) 0 and ESC ) U and ESC ) K cause G1 to
+point at translation table a), b), c), and d), respectively.
+.P
+The sequence ESC c causes a terminal reset, which is what you want if the
+screen is all garbled.
+The oft-advised "echo \[ha]V\[ha]O" will make only G0 current,
+but there is no guarantee that G0 points at table a).
+In some distributions there is a program
+.BR reset (1)
+that just does "echo \[ha][c".
+If your terminfo entry for the console is correct
+(and has an entry rs1=\eEc), then "tput reset" will also work.
+.P
+The user-defined mapping table can be set using
+.BR mapscrn (8).
+The result of the mapping is that if a symbol c is printed, the symbol
+s = map[c] is sent to the video memory.
+The bitmap that corresponds to
+s is found in the character ROM, and can be changed using
+.BR setfont (8).
+.SS Mouse tracking
+The mouse tracking facility is intended to return
+.BR xterm (1)-compatible
+mouse status reports.
+Because the console driver has no way to know
+the device or type of the mouse, these reports are returned in the
+console input stream only when the virtual terminal driver receives
+a mouse update ioctl.
+These ioctls must be generated by a mouse-aware
+user-mode application such as the
+.BR gpm (8)
+daemon.
+.P
+The mouse tracking escape sequences generated by
+\fBxterm\fP(1) encode numeric parameters in a single character as
+\fIvalue\fP+040.
+For example, \[aq]!\[aq] is 1.
+The screen coordinate system is 1-based.
+.P
+The X10 compatibility mode sends an escape sequence on button press
+encoding the location and the mouse button pressed.
+It is enabled by sending ESC [ ? 9 h and disabled with ESC [ ? 9 l.
+On button press, \fBxterm\fP(1) sends
+ESC [ M \fIbxy\fP (6 characters).
+Here \fIb\fP is button\-1,
+and \fIx\fP and \fIy\fP are the x and y coordinates of the mouse
+when the button was pressed.
+This is the same code the kernel also produces.
+.P
+Normal tracking mode (not implemented in Linux 2.0.24) sends an escape
+sequence on both button press and release.
+Modifier information is also sent.
+It is enabled by sending ESC [ ? 1000 h and disabled with
+ESC [ ? 1000 l.
+On button press or release, \fBxterm\fP(1) sends ESC [ M
+\fIbxy\fP.
+The low two bits of \fIb\fP encode button information:
+0=MB1 pressed, 1=MB2 pressed, 2=MB3 pressed, 3=release.
+The upper bits encode what modifiers were down when the button was
+pressed and are added together: 4=Shift, 8=Meta, 16=Control.
+Again \fIx\fP and
+\fIy\fP are the x and y coordinates of the mouse event.
+The upper left corner is (1,1).
+.SS Comparisons with other terminals
+Many different terminal types are described, like the Linux console,
+as being "VT100-compatible".
+Here we discuss differences between the
+Linux console and the two most important others, the DEC VT102 and
+.BR xterm (1).
+.\"
+.P
+.B Control-character handling
+.P
+The VT102 also recognized the following control characters:
+.TP
+NUL (0x00)
+was ignored;
+.TP
+ENQ (0x05)
+triggered an answerback message;
+.TP
+DC1 (0x11, \fB\[ha]Q\fP, XON)
+resumed transmission;
+.TP
+DC3 (0x13, \fB\[ha]S\fP, XOFF)
+caused VT100 to ignore (and stop transmitting)
+all codes except XOFF and XON.
+.P
+VT100-like DC1/DC3 processing may be enabled by the terminal driver.
+.P
+The
+.BR xterm (1)
+program (in VT100 mode) recognizes the control characters
+BEL, BS, HT, LF, VT, FF, CR, SO, SI, ESC.
+.\"
+.P
+.B Escape sequences
+.P
+VT100 console sequences not implemented on the Linux console:
+.TS
+l l l.
+ESC N	SS2	T{
+Single shift 2. (Select G2 character set for the next character only.)
+T}
+ESC O	SS3	T{
+Single shift 3. (Select G3 character set for the next character only.)
+T}
+ESC P	DCS	T{
+Device control string (ended by ESC \e)
+T}
+ESC X	SOS	Start of string.
+ESC \[ha]	PM	Privacy message (ended by ESC \e)
+ESC \e	ST	String terminator
+ESC * ...		Designate G2 character set
+ESC + ...		Designate G3 character set
+.TE
+.P
+The program
+.BR xterm (1)
+(in VT100 mode) recognizes ESC c, ESC # 8, ESC >, ESC =,
+ESC D, ESC E, ESC H, ESC M, ESC N, ESC O, ESC P ... ESC \e,
+ESC Z (it answers ESC [ ? 1 ; 2 c, "I am a VT100 with
+advanced video option")
+and ESC \[ha] ... ESC \e with the same meanings as indicated above.
+It accepts ESC (, ESC ), ESC *,  ESC + followed by 0, A, B for
+the DEC special character and line drawing set, UK, and US-ASCII,
+respectively.
+.P
+The user can configure \fBxterm\fP(1) to respond to VT220-specific
+control sequences, and it will identify itself as a VT52, VT100, and
+up depending on the way it is configured and initialized.
+.P
+It accepts ESC ] (OSC) for the setting of certain resources.
+In addition to the ECMA-48 string terminator (ST),
+\fBxterm\fP(1) accepts a BEL to terminate an OSC string.
+These are a few of the OSC control sequences recognized by \fBxterm\fP(1):
+.TS
+l l.
+ESC ] 0 ; \fItxt\fP ST	T{
+Set icon name and window title to \fItxt\fP.
+T}
+ESC ] 1 ; \fItxt\fP ST	Set icon name to \fItxt\fP.
+ESC ] 2 ; \fItxt\fP ST	Set window title to \fItxt\fP.
+ESC ] 4 ; \fInum\fP; \fItxt\fP ST	Set ANSI color \fInum\fP to \fItxt\fP.
+ESC ] 10 ; \fItxt\fP ST	Set dynamic text color to \fItxt\fP.
+ESC ] 4 6 ; \fIname\fP ST	T{
+Change log file to \fIname\fP (normally disabled by a compile-time option).
+T}
+ESC ] 5 0 ; \fIfn\fP ST	Set font to \fIfn\fP.
+.TE
+.P
+It recognizes the following with slightly modified meaning
+(saving more state, behaving closer to VT100/VT220):
+.TS
+l l l.
+ESC 7  DECSC	Save cursor
+ESC 8  DECRC	Restore cursor
+.TE
+.P
+It also recognizes
+.TS
+l l lx.
+ESC F		T{
+Cursor to lower left corner of screen (if enabled
+by \fBxterm\fP(1)'s \fBhpLowerleftBugCompat\fP resource).
+T}
+ESC l		Memory lock (per HP terminals).
+		Locks memory above the cursor.
+ESC m		Memory unlock (per HP terminals).
+ESC n	LS2	Invoke the G2 character set.
+ESC o	LS3	Invoke the G3 character set.
+ESC |	LS3R	Invoke the G3 character set as GR.
+ESC }	LS2R	Invoke the G2 character set as GR.
+ESC \[ti]	LS1R	Invoke the G1 character set as GR.
+.TE
+.P
+It also recognizes ESC % and provides a more complete UTF-8
+implementation than Linux console.
+.\"
+.P
+.B CSI Sequences
+.P
+Old versions of \fBxterm\fP(1), for example, from X11R5,
+interpret the blink SGR as a bold SGR.
+Later versions which implemented ANSI colors, for example,
+XFree86 3.1.2A in 1995, improved this by allowing
+the blink attribute to be displayed as a color.
+Modern versions of xterm implement blink SGR as blinking text
+and still allow colored text as an alternate rendering of SGRs.
+Stock X11R6 versions did not recognize the color-setting SGRs until
+the X11R6.8 release, which incorporated XFree86 xterm.
+All ECMA-48 CSI sequences recognized by Linux are also recognized by
+.IR xterm ,
+however \fBxterm\fP(1) implements several ECMA-48 and DEC control sequences
+not recognized by Linux.
+.P
+The \fBxterm\fP(1)
+program recognizes all of the DEC Private Mode sequences listed
+above, but none of the Linux private-mode sequences.
+For discussion of \fBxterm\fP(1)'s
+own private-mode sequences, refer to the
+\fIXterm Control Sequences\fP
+document by
+Edward Moy,
+Stephen Gildea,
+and Thomas E.\& Dickey
+available with the X distribution.
+That document, though terse, is much longer than this manual page.
+For a chronological overview,
+.P
+.RS
+.UR http://invisible\-island.net\:/xterm\:/xterm.log.html
+.UE
+.RE
+.P
+details changes to xterm.
+.P
+The \fIvttest\fP program
+.P
+.RS
+.UR http://invisible\-island.net\:/vttest/
+.UE
+.RE
+.P
+demonstrates many of these control sequences.
+The \fBxterm\fP(1) source distribution also contains sample
+scripts which exercise other features.
+.SH NOTES
+ESC 8 (DECRC) is not able to restore the character set changed with
+ESC %.
+.SH BUGS
+In Linux 2.0.23, CSI is broken, and NUL is not ignored inside
+escape sequences.
+.P
+Some older kernel versions (after Linux 2.0) interpret 8-bit control
+sequences.
+These "C1 controls" use codes between 128 and 159 to replace
+ESC [, ESC ] and similar two-byte control sequence initiators.
+There are fragments of that in modern kernels (either overlooked or
+broken by changes to support UTF-8),
+but the implementation is incomplete and should be regarded
+as unreliable.
+.P
+Linux "private mode" sequences do not follow the rules in ECMA-48
+for private mode control sequences.
+In particular, those ending with ] do not use a standard terminating
+character.
+The OSC (set palette) sequence is a greater problem,
+since \fBxterm\fP(1) may interpret this as a control sequence
+which requires a string terminator (ST).
+Unlike the \fBsetterm\fP(1) sequences which will be ignored (since
+they are invalid control sequences), the palette sequence will make
+\fBxterm\fP(1) appear to hang (though pressing the return-key
+will fix that).
+To accommodate applications which have been hardcoded to use Linux
+control sequences,
+set the \fBxterm\fP(1) resource \fBbrokenLinuxOSC\fP to true.
+.P
+An older version of this document implied that Linux recognizes the
+ECMA-48 control sequence for invisible text.
+It is ignored.
+.SH SEE ALSO
+.BR ioctl_console (2),
+.BR charsets (7)
diff --git a/man/man4/console_ioctl.4 b/man/man4/console_ioctl.4
new file mode 100644
index 000000000..5dfc68d8d
--- /dev/null
+++ b/man/man4/console_ioctl.4
@@ -0,0 +1,2 @@
+.so man2/ioctl_console.2
+.\" Link for old name of this page
diff --git a/man/man4/cpuid.4 b/man/man4/cpuid.4
new file mode 100644
index 000000000..0b38fabe3
--- /dev/null
+++ b/man/man4/cpuid.4
@@ -0,0 +1,83 @@
+.\" Copyright (c) 2009 Intel Corporation, Author Andi Kleen
+.\" Description based on comments in arch/x86/kernel/cpuid.c
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH cpuid 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cpuid \- x86 CPUID access device
+.SH DESCRIPTION
+CPUID provides an interface for querying information about the x86 CPU.
+.P
+This device is accessed by
+.BR lseek (2)
+or
+.BR pread (2)
+to the appropriate CPUID level and reading in chunks of 16 bytes.
+A larger read size means multiple reads of consecutive levels.
+.P
+The lower 32 bits of the file position is used as the incoming
+.IR %eax ,
+and the upper 32 bits of the file position as the incoming
+.IR %ecx ,
+the latter is intended for "counting"
+.I eax
+levels like
+.IR eax=4 .
+.P
+This driver uses
+.IR /dev/cpu/CPUNUM/cpuid ,
+where
+.I CPUNUM
+is the minor number,
+and on an SMP box will direct the access to CPU
+.I CPUNUM
+as listed in
+.IR /proc/cpuinfo .
+.P
+This file is protected so that it can be read only by the user
+.IR root ,
+or members of the group
+.IR root .
+.SH NOTES
+The CPUID instruction can be directly executed by a program
+using inline assembler.
+However this device allows convenient
+access to all CPUs without changing process affinity.
+.P
+Most of the information in
+.I cpuid
+is reported by the kernel in cooked form either in
+.I /proc/cpuinfo
+or through subdirectories in
+.IR /sys/devices/system/cpu .
+Direct CPUID access through this device should only
+be used in exceptional cases.
+.P
+The
+.I cpuid
+driver is not auto-loaded.
+On modular kernels you might need to use the following command
+to load it explicitly before use:
+.P
+.in +4n
+.EX
+$ modprobe cpuid
+.EE
+.in
+.P
+There is no support for CPUID functions that require additional
+input registers.
+.P
+Early i486 CPUs do not support the CPUID instruction;
+.\" arch/x86/kernel/cpuid.c cpuid_open()
+opening this device for those CPUs fails with EIO.
+.SH SEE ALSO
+.BR cpuid (1)
+.P
+Intel Corporation, Intel 64 and IA-32 Architectures
+Software Developer's Manual Volume 2A:
+Instruction Set Reference, A-M, 3-180 CPUID reference.
+.P
+Intel Corporation, Intel Processor Identification and
+the CPUID Instruction, Application note 485.
diff --git a/man/man4/dsp56k.4 b/man/man4/dsp56k.4
new file mode 100644
index 000000000..62b53700d
--- /dev/null
+++ b/man/man4/dsp56k.4
@@ -0,0 +1,107 @@
+.\" Copyright (c) 2000 lars brinkhoff <lars@nocrew.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified, Thu Jan 27 19:16:19 CET 2000, lars@nocrew.org
+.\"
+.TH dsp56k 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dsp56k \- DSP56001 interface device
+.SH SYNOPSIS
+.nf
+.B #include <asm/dsp56k.h>
+.P
+.BI "ssize_t read(int " fd ", void *" data ", size_t " length );
+.BI "ssize_t write(int " fd ", void *" data ", size_t " length );
+.P
+.BI "int ioctl(int " fd ", DSP56K_UPLOAD, struct dsp56k_upload *" program );
+.BI "int ioctl(int " fd ", DSP56K_SET_TX_WSIZE, int " wsize );
+.BI "int ioctl(int " fd ", DSP56K_SET_RX_WSIZE, int " wsize );
+.BI "int ioctl(int " fd ", DSP56K_HOST_FLAGS, struct dsp56k_host_flags *" flags );
+.BI "int ioctl(int " fd ", DSP56K_HOST_CMD, int " cmd );
+.fi
+.SH CONFIGURATION
+The
+.I dsp56k
+device is a character device with major number 55 and minor
+number 0.
+.SH DESCRIPTION
+The Motorola DSP56001 is a fully programmable 24-bit digital signal
+processor found in Atari Falcon030-compatible computers.
+The \fIdsp56k\fP special file is used to control the DSP56001, and
+to send and receive data using the bidirectional handshaked host
+port.
+.P
+To send a data stream to the signal processor, use
+.BR write (2)
+to the
+device, and
+.BR read (2)
+to receive processed data.
+The data can be sent or
+received in 8, 16, 24, or 32-bit quantities on the host side, but will
+always be seen as 24-bit quantities in the DSP56001.
+.P
+The following
+.BR ioctl (2)
+calls are used to control the
+\fIdsp56k\fP device:
+.TP
+.B DSP56K_UPLOAD
+resets the DSP56001 and uploads a program.
+The third
+.BR ioctl (2)
+argument must be a pointer to a \fIstruct dsp56k_upload\fP with members
+\fIbin\fP pointing to a DSP56001 binary program, and \fIlen\fP set to
+the length of the program, counted in 24-bit words.
+.TP
+.B DSP56K_SET_TX_WSIZE
+sets the transmit word size.
+Allowed values are in the range 1 to 4,
+and is the number of bytes that will be sent at a time to the
+DSP56001.
+These data quantities will either be padded with bytes containing zero,
+or truncated to fit the native 24-bit data format of the
+DSP56001.
+.TP
+.B DSP56K_SET_RX_WSIZE
+sets the receive word size.
+Allowed values are in the range 1 to 4,
+and is the number of bytes that will be received at a time from the DSP56001.
+These data quantities will either truncated,
+or padded with a null byte (\[aq]\e0\[aq]),
+to fit the native 24-bit data format of the DSP56001.
+.TP
+.B DSP56K_HOST_FLAGS
+read and write the host flags.
+The host flags are four
+general-purpose bits that can be read by both the hosting computer and
+the DSP56001.
+Bits 0 and 1 can be written by the host, and bits 2 and
+3 can be written by the DSP56001.
+.IP
+To access the host flags, the third
+.BR ioctl (2)
+argument must be a pointer
+to a \fIstruct dsp56k_host_flags\fP.
+If bit 0 or 1 is set in the
+\fIdir\fP member, the corresponding bit in \fIout\fP will be written
+to the host flags.
+The state of all host flags will be returned in
+the lower four bits of the \fIstatus\fP member.
+.TP
+.B DSP56K_HOST_CMD
+sends a host command.
+Allowed values are in the range 0 to 31, and is a
+user-defined command handled by the program running in the DSP56001.
+.SH FILES
+.I /dev/dsp56k
+.\" .SH AUTHORS
+.\" Fredrik Noring <noring@nocrew.org>, lars brinkhoff <lars@nocrew.org>,
+.\" Tomas Berndtsson <tomas@nocrew.org>.
+.SH SEE ALSO
+.IR linux/include/asm\-m68k/dsp56k.h ,
+.IR linux/drivers/char/dsp56k.c ,
+.UR http://dsp56k.nocrew.org/
+.UE ,
+DSP56000/DSP56001 Digital Signal Processor User's Manual
diff --git a/man/man4/fd.4 b/man/man4/fd.4
new file mode 100644
index 000000000..bf02d02fb
--- /dev/null
+++ b/man/man4/fd.4
@@ -0,0 +1,232 @@
+'\" t
+.\" Copyright (c) 1993 Michael Haardt (michael@cantor.informatik.rwth-aachen.de)
+.\" and 1994,1995 Alain Knaff (Alain.Knaff@imag.fr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified, Sun Feb 26 15:00:02 1995, faith@cs.unc.edu
+.\"
+.TH fd 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fd \- floppy disk device
+.SH CONFIGURATION
+Floppy drives are block devices with major number 2.
+Typically they
+are owned by
+root:floppy
+(i.e., user root, group floppy) and have
+either mode 0660 (access checking via group membership) or mode 0666
+(everybody has access).
+The minor
+numbers encode the device type, drive number, and controller number.
+For each device type (that is, combination of density and track count)
+there is a base minor number.
+To this base number, add the drive's
+number on its controller and 128 if the drive is on the secondary
+controller.
+In the following device tables, \fIn\fP represents the
+drive number.
+.P
+\fBWarning: if you use formats with more tracks
+than supported by your drive, you may cause it mechanical damage.\fP
+Trying once if more tracks than the usual 40/80 are supported should not
+damage it, but no warranty is given for that.
+If you are not sure, don't create device
+entries for those formats, so as to prevent their usage.
+.P
+Drive-independent device files which automatically detect the media
+format and capacity:
+.TS
+l c
+l c.
+Name	Base
+	minor #
+_
+\fBfd\fP\fIn\fP	0
+.TE
+.P
+5.25 inch double-density device files:
+.TS
+lw(1i) l l l l c
+lw(1i) c c c c c.
+Name	Capacity	Cyl.	Sect.	Heads	Base
+	KiB				minor #
+_
+\fBfd\fP\fIn\fP\fBd360\fP	360	40	9	2	4
+.TE
+.P
+5.25 inch high-density device files:
+.TS
+lw(1i) l l l l c
+lw(1i) c c c c c.
+Name	Capacity	Cyl.	Sect.	Heads	Base
+	KiB				minor #
+_
+\fBfd\fP\fIn\fP\fBh360\fP	360	40	9	2	20
+\fBfd\fP\fIn\fP\fBh410\fP	410	41	10	2	48
+\fBfd\fP\fIn\fP\fBh420\fP	420	42	10	2	64
+\fBfd\fP\fIn\fP\fBh720\fP	720	80	9	2	24
+\fBfd\fP\fIn\fP\fBh880\fP	880	80	11	2	80
+\fBfd\fP\fIn\fP\fBh1200\fP	1200	80	15	2	8
+\fBfd\fP\fIn\fP\fBh1440\fP	1440	80	18	2	40
+\fBfd\fP\fIn\fP\fBh1476\fP	1476	82	18	2	56
+\fBfd\fP\fIn\fP\fBh1494\fP	1494	83	18	2	72
+\fBfd\fP\fIn\fP\fBh1600\fP	1600	80	20	2	92
+.TE
+.P
+3.5 inch double-density device files:
+.TS
+lw(1i) l l l l c
+lw(1i) c c c c c.
+Name	Capacity	Cyl.	Sect.	Heads	Base
+	KiB				minor #
+_
+\fBfd\fP\fIn\fP\fBu360\fP	360	80	9	1	12
+\fBfd\fP\fIn\fP\fBu720\fP	720	80	9	2	16
+\fBfd\fP\fIn\fP\fBu800\fP	800	80	10	2	120
+\fBfd\fP\fIn\fP\fBu1040\fP	1040	80	13	2	84
+\fBfd\fP\fIn\fP\fBu1120\fP	1120	80	14	2	88
+.TE
+.P
+3.5 inch high-density device files:
+.TS
+lw(1i) l l l l c
+lw(1i) c c c c c.
+Name	Capacity	Cyl.	Sect.	Heads	Base
+	KiB				minor #
+_
+\fBfd\fP\fIn\fP\fBu360\fP	360	40	9	2	12
+\fBfd\fP\fIn\fP\fBu720\fP	720	80	9	2	16
+\fBfd\fP\fIn\fP\fBu820\fP	820	82	10	2	52
+\fBfd\fP\fIn\fP\fBu830\fP	830	83	10	2	68
+\fBfd\fP\fIn\fP\fBu1440\fP	1440	80	18	2	28
+\fBfd\fP\fIn\fP\fBu1600\fP	1600	80	20	2	124
+\fBfd\fP\fIn\fP\fBu1680\fP	1680	80	21	2	44
+\fBfd\fP\fIn\fP\fBu1722\fP	1722	82	21	2	60
+\fBfd\fP\fIn\fP\fBu1743\fP	1743	83	21	2	76
+\fBfd\fP\fIn\fP\fBu1760\fP	1760	80	22	2	96
+\fBfd\fP\fIn\fP\fBu1840\fP	1840	80	23	2	116
+\fBfd\fP\fIn\fP\fBu1920\fP	1920	80	24	2	100
+.TE
+.P
+3.5 inch extra-density device files:
+.TS
+lw(1i) l l l l c
+lw(1i) c c c c c.
+Name	Capacity	Cyl.	Sect.	Heads	Base
+	KiB				minor #
+_
+\fBfd\fP\fIn\fP\fBu2880\fP	2880	80	36	2	32
+\fBfd\fP\fIn\fP\fBCompaQ\fP	2880	80	36	2	36
+\fBfd\fP\fIn\fP\fBu3200\fP	3200	80	40	2	104
+\fBfd\fP\fIn\fP\fBu3520\fP	3520	80	44	2	108
+\fBfd\fP\fIn\fP\fBu3840\fP	3840	80	48	2	112
+.TE
+.SH DESCRIPTION
+\fBfd\fP special files access the floppy disk drives in raw mode.
+The following
+.BR ioctl (2)
+calls are supported by \fBfd\fP devices:
+.TP
+.B FDCLRPRM
+clears the media information of a drive (geometry of disk in drive).
+.TP
+.B FDSETPRM
+sets the media information of a drive.
+The media information will be
+lost when the media is changed.
+.TP
+.B FDDEFPRM
+sets the media information of a drive (geometry of disk in drive).
+The media information will not be lost when the media is changed.
+This will disable autodetection.
+In order to reenable autodetection, you
+have to issue an \fBFDCLRPRM\fP.
+.TP
+.B FDGETDRVTYP
+returns the type of a drive (name parameter).
+For formats which work
+in several drive types, \fBFDGETDRVTYP\fP returns a name which is
+appropriate for the oldest drive type which supports this format.
+.TP
+.B FDFLUSH
+invalidates the buffer cache for the given drive.
+.TP
+.B FDSETMAXERRS
+sets the error thresholds for reporting errors, aborting the operation,
+recalibrating, resetting, and reading sector by sector.
+.TP
+.B FDSETMAXERRS
+gets the current error thresholds.
+.TP
+.B FDGETDRVTYP
+gets the internal name of the drive.
+.TP
+.B FDWERRORCLR
+clears the write error statistics.
+.TP
+.B FDWERRORGET
+reads the write error statistics.
+These include the total number of
+write errors, the location and disk of the first write error, and the
+location and disk of the last write error.
+Disks are identified by a
+generation number which is incremented at (almost) each disk change.
+.TP
+.B FDTWADDLE
+Switch the drive motor off for a few microseconds.
+This might be
+needed in order to access a disk whose sectors are too close together.
+.TP
+.B FDSETDRVPRM
+sets various drive parameters.
+.TP
+.B FDGETDRVPRM
+reads these parameters back.
+.TP
+.B FDGETDRVSTAT
+gets the cached drive state (disk changed, write protected et al.)
+.TP
+.B FDPOLLDRVSTAT
+polls the drive and return its state.
+.TP
+.B FDGETFDCSTAT
+gets the floppy controller state.
+.TP
+.B FDRESET
+resets the floppy controller under certain conditions.
+.TP
+.B FDRAWCMD
+sends a raw command to the floppy controller.
+.P
+For more precise information, consult also the \fI<linux/fd.h>\fP and
+\fI<linux/fdreg.h>\fP include files, as well as the
+.BR floppycontrol (1)
+manual page.
+.SH FILES
+.I /dev/fd*
+.SH NOTES
+The various formats permit reading and writing many types of disks.
+However, if a floppy is formatted with an inter-sector gap that is too small,
+performance may drop,
+to the point of needing a few seconds to access an entire track.
+To prevent this, use interleaved formats.
+.P
+It is not possible to
+read floppies which are formatted using GCR (group code recording),
+which is used by Apple II and Macintosh computers (800k disks).
+.P
+Reading floppies which are hard sectored (one hole per sector, with
+the index hole being a little skewed) is not supported.
+This used to be common with older 8-inch floppies.
+.\" .SH AUTHORS
+.\" Alain Knaff (Alain.Knaff@imag.fr), David Niemi
+.\" (niemidc@clark.net), Bill Broadhurst (bbroad@netcom.com).
+.SH SEE ALSO
+.BR chown (1),
+.BR floppycontrol (1),
+.BR getfdprm (1),
+.BR mknod (1),
+.BR superformat (1),
+.BR mount (8),
+.BR setfdprm (8)
diff --git a/man/man4/full.4 b/man/man4/full.4
new file mode 100644
index 000000000..92c440bc6
--- /dev/null
+++ b/man/man4/full.4
@@ -0,0 +1,46 @@
+.\" This man-page is Copyright (C) 1997 John S. Kallal
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" correction, aeb, 970825
+.TH full 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+full \- always full device
+.SH CONFIGURATION
+If your system does not have
+.I /dev/full
+created already, it
+can be created with the following commands:
+.P
+.in +4n
+.EX
+mknod \-m 666 /dev/full c 1 7
+chown root:root /dev/full
+.EE
+.in
+.SH DESCRIPTION
+The file
+.I /dev/full
+has major device number 1
+and minor device number 7.
+.P
+Writes to the
+.I /dev/full
+device fail with an
+.B ENOSPC
+error.
+This can be used to test how a program handles disk-full errors.
+.P
+Reads from the
+.I /dev/full
+device will return \e0 characters.
+.P
+Seeks on
+.I /dev/full
+will always succeed.
+.SH FILES
+.I /dev/full
+.SH SEE ALSO
+.BR mknod (1),
+.BR null (4),
+.BR zero (4)
diff --git a/man/man4/fuse.4 b/man/man4/fuse.4
new file mode 100644
index 000000000..1e2dd7ae5
--- /dev/null
+++ b/man/man4/fuse.4
@@ -0,0 +1,535 @@
+.\" Copyright (c) 2016 Julia Computing Inc, Keno Fischer
+.\" Description based on include/uapi/fuse.h and code in fs/fuse
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH fuse 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fuse \- Filesystem in Userspace (FUSE) device
+.SH SYNOPSIS
+.nf
+.B #include <linux/fuse.h>
+.fi
+.SH DESCRIPTION
+This device is the primary interface between the FUSE filesystem driver
+and a user-space process wishing to provide the filesystem (referred to
+in the rest of this manual page as the
+.IR "filesystem daemon" ).
+This manual page is intended for those
+interested in understanding the kernel interface itself.
+Those implementing a FUSE filesystem may wish to make use of
+a user-space library such as
+.I libfuse
+that abstracts away the low-level interface.
+.P
+At its core, FUSE is a simple client-server protocol, in which the Linux
+kernel is the client and the daemon is the server.
+After obtaining a file descriptor for this device, the daemon may
+.BR read (2)
+requests from that file descriptor and is expected to
+.BR write (2)
+back its replies.
+It is important to note that a file descriptor is
+associated with a unique FUSE filesystem.
+In particular, opening a second copy of this device,
+will not allow access to resources created
+through the first file descriptor (and vice versa).
+.\"
+.SS The basic protocol
+Every message that is read by the daemon begins with a header described by
+the following structure:
+.P
+.in +4n
+.EX
+struct fuse_in_header {
+    uint32_t len;       /* Total length of the data,
+                           including this header */
+    uint32_t opcode;    /* The kind of operation (see below) */
+    uint64_t unique;    /* A unique identifier for this request */
+    uint64_t nodeid;    /* ID of the filesystem object
+                           being operated on */
+    uint32_t uid;       /* UID of the requesting process */
+    uint32_t gid;       /* GID of the requesting process */
+    uint32_t pid;       /* PID of the requesting process */
+    uint32_t padding;
+};
+.EE
+.in
+.P
+The header is followed by a variable-length data portion
+(which may be empty) specific to the requested operation
+(the requested operation is indicated by
+.IR opcode ).
+.P
+The daemon should then process the request and if applicable send
+a reply (almost all operations require a reply; if they do not,
+this is documented below), by performing a
+.BR write (2)
+to the file descriptor.
+All replies must start with the following header:
+.P
+.in +4n
+.EX
+struct fuse_out_header {
+    uint32_t len;       /* Total length of data written to
+                           the file descriptor */
+    int32_t  error;     /* Any error that occurred (0 if none) */
+    uint64_t unique;    /* The value from the
+                           corresponding request */
+};
+.EE
+.in
+.P
+This header is also followed by (potentially empty) variable-sized
+data depending on the executed request.
+However, if the reply is an error reply (i.e.,
+.I error
+is set),
+then no further payload data should be sent, independent of the request.
+.\"
+.SS Exchanged messages
+This section should contain documentation for each of the messages
+in the protocol.
+This manual page is currently incomplete,
+so not all messages are documented.
+For each message, first the struct sent by the kernel is given,
+followed by a description of the semantics of the message.
+.TP
+.B FUSE_INIT
+.IP
+.in +4n
+.EX
+struct fuse_init_in {
+    uint32_t major;
+    uint32_t minor;
+    uint32_t max_readahead; /* Since protocol v7.6 */
+    uint32_t flags;         /* Since protocol v7.6 */
+};
+.EE
+.in
+.IP
+This is the first request sent by the kernel to the daemon.
+It is used to negotiate the protocol version and other filesystem parameters.
+Note that the protocol version may affect the layout of any structure
+in the protocol (including this structure).
+The daemon must thus remember the negotiated version
+and flags for each session.
+As of the writing of this man page,
+the highest supported kernel protocol version is
+.IR 7.26 .
+.IP
+Users should be aware that the descriptions in this manual page
+may be incomplete or incorrect for older or more recent protocol versions.
+.IP
+The reply for this request has the following format:
+.IP
+.in +4n
+.EX
+struct fuse_init_out {
+    uint32_t major;
+    uint32_t minor;
+    uint32_t max_readahead;   /* Since v7.6 */
+    uint32_t flags;           /* Since v7.6; some flags bits
+                                 were introduced later */
+    uint16_t max_background;  /* Since v7.13 */
+    uint16_t congestion_threshold;  /* Since v7.13 */
+    uint32_t max_write;       /* Since v7.5 */
+    uint32_t time_gran;       /* Since v7.6 */
+    uint32_t unused[9];
+};
+.EE
+.in
+.IP
+If the major version supported by the kernel is larger than that supported
+by the daemon, the reply shall consist of only
+.I uint32_t major
+(following the usual header),
+indicating the largest major version supported by the daemon.
+The kernel will then issue a new
+.B FUSE_INIT
+request conforming to the older version.
+In the reverse case, the daemon should
+quietly fall back to the kernel's major version.
+.IP
+The negotiated minor version is considered to be the minimum
+of the minor versions provided by the daemon and the kernel and
+both parties should use the protocol corresponding to said minor version.
+.TP
+.B FUSE_GETATTR
+.IP
+.in +4n
+.EX
+struct fuse_getattr_in {
+    uint32_t getattr_flags;
+    uint32_t dummy;
+    uint64_t fh;      /* Set only if
+                         (getattr_flags & FUSE_GETATTR_FH)
+};
+.EE
+.in
+.IP
+The requested operation is to compute the attributes to be returned
+by
+.BR stat (2)
+and similar operations for the given filesystem object.
+The object for which the attributes should be computed is indicated
+either by
+.I header\->nodeid
+or, if the
+.B FUSE_GETATTR_FH
+flag is set, by the file handle
+.IR fh .
+The latter case of operation is analogous to
+.BR fstat (2).
+.IP
+For performance reasons, these attributes may be cached in the kernel for
+a specified duration of time.
+While the cache timeout has not been exceeded,
+the attributes will be served from the cache and will not cause additional
+.B FUSE_GETATTR
+requests.
+.IP
+The computed attributes and the requested
+cache timeout should then be returned in the following structure:
+.IP
+.in +4n
+.EX
+struct fuse_attr_out {
+    /* Attribute cache duration (seconds + nanoseconds) */
+    uint64_t attr_valid;
+    uint32_t attr_valid_nsec;
+    uint32_t dummy;
+    struct fuse_attr {
+        uint64_t ino;
+        uint64_t size;
+        uint64_t blocks;
+        uint64_t atime;
+        uint64_t mtime;
+        uint64_t ctime;
+        uint32_t atimensec;
+        uint32_t mtimensec;
+        uint32_t ctimensec;
+        uint32_t mode;
+        uint32_t nlink;
+        uint32_t uid;
+        uint32_t gid;
+        uint32_t rdev;
+        uint32_t blksize;
+        uint32_t padding;
+    } attr;
+};
+.EE
+.in
+.TP
+.B FUSE_ACCESS
+.IP
+.in +4n
+.EX
+struct fuse_access_in {
+    uint32_t mask;
+    uint32_t padding;
+};
+.EE
+.in
+.IP
+If the
+.I default_permissions
+mount options is not used, this request may be used for permissions checking.
+No reply data is expected, but errors may be indicated
+as usual by setting the
+.I error
+field in the reply header (in particular, access denied errors
+may be indicated by returning
+.BR \-EACCES ).
+.TP
+.BR FUSE_OPEN " and " FUSE_OPENDIR
+.in +4n
+.EX
+struct fuse_open_in {
+    uint32_t flags;     /* The flags that were passed
+                           to the open(2) */
+    uint32_t unused;
+};
+.EE
+.in
+.IP
+The requested operation is to open the node indicated by
+.IR header\->nodeid .
+The exact semantics of what this means will depend on the
+filesystem being implemented.
+However, at the very least the
+filesystem should validate that the requested
+.I flags
+are valid for the indicated resource and then send a reply with the
+following format:
+.IP
+.in +4n
+.EX
+struct fuse_open_out {
+    uint64_t fh;
+    uint32_t open_flags;
+    uint32_t padding;
+};
+.EE
+.in
+.IP
+The
+.I fh
+field is an opaque identifier that the kernel will use to refer
+to this resource
+The
+.I open_flags
+field is a bit mask of any number of the flags
+that indicate properties of this file handle to the kernel:
+.RS 7
+.TP 18
+.B FOPEN_DIRECT_IO
+Bypass page cache for this open file.
+.TP
+.B FOPEN_KEEP_CACHE
+Don't invalidate the data cache on open.
+.TP
+.B FOPEN_NONSEEKABLE
+The file is not seekable.
+.RE
+.TP
+.BR FUSE_READ " and " FUSE_READDIR
+.IP
+.in +4n
+.EX
+struct fuse_read_in {
+    uint64_t fh;
+    uint64_t offset;
+    uint32_t size;
+    uint32_t read_flags;
+    uint64_t lock_owner;
+    uint32_t flags;
+    uint32_t padding;
+};
+.EE
+.in
+.IP
+The requested action is to read up to
+.I size
+bytes of the file or directory, starting at
+.IR offset .
+The bytes should be returned directly following the usual reply header.
+.TP
+.B FUSE_INTERRUPT
+.in +4n
+.EX
+struct fuse_interrupt_in {
+    uint64_t unique;
+};
+.EE
+.in
+.IP
+The requested action is to cancel the pending operation indicated by
+.IR unique .
+This request requires no response.
+However, receipt of this message does
+not by itself cancel the indicated operation.
+The kernel will still expect a reply to said operation (e.g., an
+.I EINTR
+error or a short read).
+At most one
+.B FUSE_INTERRUPT
+request will be issued for a given operation.
+After issuing said operation,
+the kernel will wait uninterruptibly for completion of the indicated request.
+.TP
+.B FUSE_LOOKUP
+Directly following the header is a filename to be looked up in the directory
+indicated by
+.IR header\->nodeid .
+The expected reply is of the form:
+.IP
+.in +4n
+.EX
+struct fuse_entry_out {
+    uint64_t nodeid;            /* Inode ID */
+    uint64_t generation;        /* Inode generation */
+    uint64_t entry_valid;
+    uint64_t attr_valid;
+    uint32_t entry_valid_nsec;
+    uint32_t attr_valid_nsec;
+    struct fuse_attr attr;
+};
+.EE
+.in
+.IP
+The combination of
+.I nodeid
+and
+.I generation
+must be unique for the filesystem's lifetime.
+.IP
+The interpretation of timeouts and
+.I attr
+is as for
+.BR FUSE_GETATTR .
+.TP
+.B FUSE_FLUSH
+.in +4n
+.EX
+struct fuse_flush_in {
+    uint64_t fh;
+    uint32_t unused;
+    uint32_t padding;
+    uint64_t lock_owner;
+};
+.EE
+.in
+.IP
+The requested action is to flush any pending changes to the indicated
+file handle.
+No reply data is expected.
+However, an empty reply message
+still needs to be issued once the flush operation is complete.
+.TP
+.BR FUSE_RELEASE " and " FUSE_RELEASEDIR
+.in +4n
+.EX
+struct fuse_release_in {
+    uint64_t fh;
+    uint32_t flags;
+    uint32_t release_flags;
+    uint64_t lock_owner;
+};
+.EE
+.in
+.IP
+These are the converse of
+.B FUSE_OPEN
+and
+.B FUSE_OPENDIR
+respectively.
+The daemon may now free any resources associated with the
+file handle
+.I fh
+as the kernel will no longer refer to it.
+There is no reply data associated with this request,
+but a reply still needs to be issued once the request has
+been completely processed.
+.TP
+.B FUSE_STATFS
+This operation implements
+.BR statfs (2)
+for this filesystem.
+There is no input data associated with this request.
+The expected reply data has the following structure:
+.IP
+.in +4n
+.EX
+struct fuse_kstatfs {
+    uint64_t blocks;
+    uint64_t bfree;
+    uint64_t bavail;
+    uint64_t files;
+    uint64_t ffree;
+    uint32_t bsize;
+    uint32_t namelen;
+    uint32_t frsize;
+    uint32_t padding;
+    uint32_t spare[6];
+};
+\&
+struct fuse_statfs_out {
+    struct fuse_kstatfs st;
+};
+.EE
+.in
+.IP
+For the interpretation of these fields, see
+.BR statfs (2).
+.SH ERRORS
+.TP
+.B E2BIG
+Returned from
+.BR read (2)
+operations when the kernel's request is too large for the provided buffer
+and the request was
+.BR FUSE_SETXATTR .
+.TP
+.B EINVAL
+Returned from
+.BR write (2)
+if validation of the reply failed.
+Not all mistakes in replies will be caught by this validation.
+However, basic mistakes, such as short replies or an incorrect
+.I unique
+value, are detected.
+.TP
+.B EIO
+Returned from
+.BR read (2)
+operations when the kernel's request is too large for the provided buffer.
+.IP
+.IR Note :
+There are various ways in which incorrect use of these interfaces can cause
+operations on the provided filesystem's files and directories to fail with
+.BR EIO .
+Among the possible incorrect uses are:
+.RS
+.IP \[bu] 3
+changing
+.I mode & S_IFMT
+for an inode that has previously been reported to the kernel; or
+.IP \[bu]
+giving replies to the kernel that are shorter than what the kernel expected.
+.RE
+.TP
+.B ENODEV
+Returned from
+.BR read (2)
+and
+.BR write (2)
+if the FUSE filesystem was unmounted.
+.TP
+.B EPERM
+Returned from operations on a
+.I /dev/fuse
+file descriptor that has not been mounted.
+.SH STANDARDS
+Linux.
+.SH NOTES
+The following messages are not yet documented in this manual page:
+.P
+.\" FIXME: Document the following.
+.in +4n
+.EX
+.B FUSE_BATCH_FORGET
+.B FUSE_BMAP
+.B FUSE_CREATE
+.B FUSE_DESTROY
+.B FUSE_FALLOCATE
+.B FUSE_FORGET
+.B FUSE_FSYNC
+.B FUSE_FSYNCDIR
+.B FUSE_GETLK
+.B FUSE_GETXATTR
+.B FUSE_IOCTL
+.B FUSE_LINK
+.B FUSE_LISTXATTR
+.B FUSE_LSEEK
+.B FUSE_MKDIR
+.B FUSE_MKNOD
+.B FUSE_NOTIFY_REPLY
+.B FUSE_POLL
+.B FUSE_READDIRPLUS
+.B FUSE_READLINK
+.B FUSE_REMOVEXATTR
+.B FUSE_RENAME
+.B FUSE_RENAME2
+.B FUSE_RMDIR
+.B FUSE_SETATTR
+.B FUSE_SETLK
+.B FUSE_SETLKW
+.B FUSE_SYMLINK
+.B FUSE_UNLINK
+.B FUSE_WRITE
+.EE
+.in
+.SH SEE ALSO
+.BR fusermount (1),
+.BR mount.fuse (8)
diff --git a/man/man4/hd.4 b/man/man4/hd.4
new file mode 100644
index 000000000..c45a8141f
--- /dev/null
+++ b/man/man4/hd.4
@@ -0,0 +1,82 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 16:56:20 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Mon Oct 21 21:38:51 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" (and some more by aeb)
+.\"
+.TH hd 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hd \- MFM/IDE hard disk devices
+.SH DESCRIPTION
+The
+.B hd*
+devices are block devices to access MFM/IDE hard disk drives
+in raw mode.
+The master drive on the primary IDE controller (major device
+number 3) is
+.BR hda ;
+the slave drive is
+.BR hdb .
+The master drive of the second controller (major device number 22)
+is
+.B hdc
+and the slave is
+.BR hdd .
+.P
+General IDE block device names have the form
+.BI hd X\c
+, or
+.BI hd XP\c
+, where
+.I X
+is a letter denoting the physical drive, and
+.I P
+is a number denoting the partition on that physical drive.
+The first form,
+.BI hd X\c
+, is used to address the whole drive.
+Partition numbers are assigned in the order the partitions
+are discovered, and only nonempty, nonextended partitions
+get a number.
+However, partition numbers 1\[en]4 are given to the
+four partitions described in the MBR (the "primary" partitions),
+regardless of whether they are unused or extended.
+Thus, the first logical partition will be
+.BI hd X 5\c
+\&.
+Both DOS-type partitioning and BSD-disklabel partitioning are supported.
+You can have at most 63 partitions on an IDE disk.
+.P
+For example,
+.I /dev/hda
+refers to all of the first IDE drive in the system; and
+.I /dev/hdb3
+refers to the third DOS "primary" partition on the second one.
+.P
+They are typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 660 /dev/hda b 3 0
+mknod \-m 660 /dev/hda1 b 3 1
+mknod \-m 660 /dev/hda2 b 3 2
+\&...
+mknod \-m 660 /dev/hda8 b 3 8
+mknod \-m 660 /dev/hdb b 3 64
+mknod \-m 660 /dev/hdb1 b 3 65
+mknod \-m 660 /dev/hdb2 b 3 66
+\&...
+mknod \-m 660 /dev/hdb8 b 3 72
+chown root:disk /dev/hd*
+.EE
+.in
+.SH FILES
+.I /dev/hd*
+.SH SEE ALSO
+.BR chown (1),
+.BR mknod (1),
+.BR sd (4),
+.BR mount (8)
diff --git a/man/man4/hpsa.4 b/man/man4/hpsa.4
new file mode 100644
index 000000000..6c24c9cb0
--- /dev/null
+++ b/man/man4/hpsa.4
@@ -0,0 +1,240 @@
+.\" Copyright (C) 2011, Hewlett-Packard Development Company, L.P.
+.\" Written by Stephen M. Cameron <scameron@beardog.cce.hp.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.\"
+.\" shorthand for double quote that works everywhere.
+.ds q \N'34'
+.TH hpsa 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hpsa \- HP Smart Array SCSI driver
+.SH SYNOPSIS
+.nf
+modprobe hpsa [ hpsa_allow_any=1 ]
+.fi
+.SH DESCRIPTION
+.B hpsa
+is a SCSI driver for HP Smart Array RAID controllers.
+.SS Options
+.IR "hpsa_allow_any=1" :
+This option allows the driver to attempt to operate on
+any HP Smart Array hardware RAID controller,
+even if it is not explicitly known to the driver.
+This allows newer hardware to work with older drivers.
+Typically this is used to allow installation of
+operating systems from media that predates the
+RAID controller, though it may also be used to enable
+.B hpsa
+to drive older controllers that would normally be handled by the
+.BR cciss (4)
+driver.
+These older boards have not been tested and are
+not supported with
+.BR hpsa ,
+and
+.BR cciss (4)
+should still be used for these.
+.SS Supported hardware
+The
+.B hpsa
+driver supports the following Smart Array boards:
+.P
+.nf
+    Smart Array P700M
+    Smart Array P212
+    Smart Array P410
+    Smart Array P410i
+    Smart Array P411
+    Smart Array P812
+    Smart Array P712m
+    Smart Array P711m
+    StorageWorks P1210m
+.fi
+.P
+.\" commit 135ae6edeb51979d0998daf1357f149a7d6ebb08
+Since Linux 4.14, the following Smart Array boards are also supported:
+.P
+.nf
+    Smart Array 5300
+    Smart Array 5312
+    Smart Array 532
+    Smart Array 5i
+    Smart Array 6400
+    Smart Array 6400 EM
+    Smart Array 641
+    Smart Array 642
+    Smart Array 6i
+    Smart Array E200
+    Smart Array E200i
+    Smart Array E200i
+    Smart Array E200i
+    Smart Array E200i
+    Smart Array E500
+    Smart Array P400
+    Smart Array P400i
+    Smart Array P600
+    Smart Array P700m
+    Smart Array P800
+.fi
+.SS Configuration details
+To configure HP Smart Array controllers,
+use the HP Array Configuration Utility (either
+.BR hpacuxe (8)
+or
+.BR hpacucli (8))
+or the Offline ROM-based Configuration Utility (ORCA)
+run from the Smart Array's option ROM at boot time.
+.SH FILES
+.SS Device nodes
+Logical drives are accessed via the SCSI disk driver
+.RB ( sd (4)),
+tape drives via the SCSI tape driver
+.RB ( st (4)),
+and
+the RAID controller via the SCSI generic driver
+.RB ( sg (4)),
+with device nodes named
+.IR /dev/sd* ,
+.IR /dev/st* ,
+and
+.IR /dev/sg* ,
+respectively.
+.SS HPSA-specific host attribute files in /sys
+.TP
+.I /sys/class/scsi_host/host*/rescan
+This is a write-only attribute.
+Writing to this attribute will cause the driver to scan for
+new, changed, or removed devices (e.g., hot-plugged tape drives,
+or newly configured or deleted logical drives, etc.)
+and notify the SCSI midlayer of any changes detected.
+Normally a rescan is triggered automatically
+by HP's Array Configuration Utility (either the GUI or the
+command-line variety);
+thus, for logical drive changes, the user should not
+normally have to use this attribute.
+This attribute may be useful when hot plugging devices like tape drives,
+or entire storage boxes containing preconfigured logical drives.
+.TP
+.I /sys/class/scsi_host/host*/firmware_revision
+This attribute contains the firmware version of the Smart Array.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+# \fBcd /sys/class/scsi_host/host4\fP
+# \fBcat firmware_revision\fP
+7.14
+.EE
+.in
+.\"
+.SS HPSA-specific disk attribute files in /sys
+.TP
+.I /sys/class/scsi_disk/c:b:t:l/device/unique_id
+This attribute contains a 32 hex-digit unique ID for each logical drive.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+# \fBcd /sys/class/scsi_disk/4:0:0:0/device\fP
+# \fBcat unique_id\fP
+600508B1001044395355323037570F77
+.EE
+.in
+.TP
+.I /sys/class/scsi_disk/c:b:t:l/device/raid_level
+This attribute contains the RAID level of each logical drive.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+# \fBcd /sys/class/scsi_disk/4:0:0:0/device\fP
+# \fBcat raid_level\fP
+RAID 0
+.EE
+.in
+.TP
+.I /sys/class/scsi_disk/c:b:t:l/device/lunid
+This attribute contains the 16 hex-digit (8 byte) LUN ID
+by which a logical drive or physical device can be addressed.
+.IR c : b : t : l
+are the controller, bus, target, and lun of the device.
+.P
+For example:
+.IP
+.in +4n
+.EX
+# \fBcd /sys/class/scsi_disk/4:0:0:0/device\fP
+# \fBcat lunid\fP
+0x0000004000000000
+.EE
+.in
+.\"
+.SS Supported ioctl() operations
+For compatibility with applications written for the
+.BR cciss (4)
+driver, many, but
+not all of the ioctls supported by the
+.BR cciss (4)
+driver are also supported by the
+.B hpsa
+driver.
+The data structures used by these ioctls are described in
+the Linux kernel source file
+.IR include/linux/cciss_ioctl.h .
+.TP
+.B CCISS_DEREGDISK
+.TQ
+.B CCISS_REGNEWDISK
+.TQ
+.B CCISS_REGNEWD
+These three ioctls all do exactly the same thing,
+which is to cause the driver to rescan for new devices.
+This does exactly the same thing as writing to the
+hpsa-specific host "rescan" attribute.
+.TP
+.B CCISS_GETPCIINFO
+Returns PCI domain, bus, device, and function and "board ID" (PCI subsystem ID).
+.TP
+.B CCISS_GETDRIVVER
+Returns driver version in three bytes encoded as:
+.IP
+.in +4n
+.EX
+(major_version << 16) | (minor_version << 8) |
+    (subminor_version)
+.EE
+.in
+.TP
+.B CCISS_PASSTHRU
+.TQ
+.B CCISS_BIG_PASSTHRU
+Allows "BMIC" and "CISS" commands to be passed through to the Smart Array.
+These are used extensively by the HP Array Configuration Utility,
+SNMP storage agents, and so on.
+See
+.I cciss_vol_status
+at
+.UR http://cciss.sf.net
+.UE
+for some examples.
+.SH SEE ALSO
+.BR cciss (4),
+.BR sd (4),
+.BR st (4),
+.BR cciss_vol_status (8),
+.BR hpacucli (8),
+.BR hpacuxe (8)
+.P
+.UR http://cciss.sf.net
+.UE ,
+and
+.I Documentation/scsi/hpsa.txt
+and
+.I Documentation/ABI/testing/sysfs\-bus\-pci\-devices\-cciss
+in the Linux kernel source tree
+.\" .SH AUTHORS
+.\" Don Brace, Steve Cameron, Tom Lawler, Mike Miller, Scott Teel
+.\" and probably some other people.
diff --git a/man/man4/initrd.4 b/man/man4/initrd.4
new file mode 100644
index 000000000..6c63d6b13
--- /dev/null
+++ b/man/man4/initrd.4
@@ -0,0 +1,479 @@
+.\" This man-page is Copyright (C) 1997 John S. Kallal
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" If the you wish to distribute versions of this work under other
+.\" conditions than the above, please contact the author(s) at the following
+.\" for permission:
+.\"
+.\"  John S. Kallal -
+.\"	email: <kallal@voicenet.com>
+.\"	mail: 518 Kerfoot Farm RD, Wilmington, DE 19803-2444, USA
+.\"	phone: (302)654-5478
+.\"
+.\" $Id: initrd.4,v 0.9 1997/11/07 05:05:32 kallal Exp kallal $
+.TH initrd 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+initrd \- boot loader initialized RAM disk
+.SH CONFIGURATION
+.I /dev/initrd
+is a read-only block device assigned
+major number 1 and minor number 250.
+Typically
+.I /dev/initrd
+is owned by
+root:disk
+with mode 0400 (read access by root only).
+If the Linux system does not have
+.I /dev/initrd
+already created, it can be created with the following commands:
+.P
+.in +4n
+.EX
+mknod \-m 400 /dev/initrd b 1 250
+chown root:disk /dev/initrd
+.EE
+.in
+.P
+Also, support for both "RAM disk" and "Initial RAM disk"
+(e.g.,
+.B CONFIG_BLK_DEV_RAM=y
+and
+.BR CONFIG_BLK_DEV_INITRD=y )
+must be compiled directly into the Linux kernel to use
+.IR /dev/initrd .
+When using
+.IR /dev/initrd ,
+the RAM disk driver cannot be loaded as a module.
+.\"
+.\"
+.\"
+.SH DESCRIPTION
+The special file
+.I /dev/initrd
+is a read-only block device.
+This device is a RAM disk that is initialized (e.g., loaded)
+by the boot loader before the kernel is started.
+The kernel then can use
+.IR /dev/initrd "'s"
+contents for a two-phase system boot-up.
+.P
+In the first boot-up phase, the kernel starts up
+and mounts an initial root filesystem from the contents of
+.I /dev/initrd
+(e.g., RAM disk initialized by the boot loader).
+In the second phase, additional drivers or other modules
+are loaded from the initial root device's contents.
+After loading the additional modules, a new root filesystem
+(i.e., the normal root filesystem) is mounted from a
+different device.
+.\"
+.\"
+.\"
+.SS Boot-up operation
+When booting up with
+.BR initrd ,
+the system boots as follows:
+.IP (1) 5
+The boot loader loads the kernel program and
+.IR /dev/initrd 's
+contents into memory.
+.IP (2)
+On kernel startup,
+the kernel uncompresses and copies the contents of the device
+.I /dev/initrd
+onto device
+.I /dev/ram0
+and then frees the memory used by
+.IR /dev/initrd .
+.IP (3)
+The kernel then read-write mounts the device
+.I /dev/ram0
+as the initial root filesystem.
+.IP (4)
+If the indicated normal root filesystem is also the initial
+root filesystem (e.g.,
+.IR /dev/ram0 )
+then the kernel skips to the last step for the usual boot sequence.
+.IP (5)
+If the executable file
+.I /linuxrc
+is present in the initial root filesystem,
+.I /linuxrc
+is executed with UID 0.
+(The file
+.I /linuxrc
+must have executable permission.
+The file
+.I /linuxrc
+can be any valid executable, including a shell script.)
+.IP (6)
+If
+.I /linuxrc
+is not executed or when
+.I /linuxrc
+terminates, the normal root filesystem is mounted.
+(If
+.I /linuxrc
+exits with any filesystems mounted on the initial root
+filesystem, then the behavior of the kernel is
+.BR UNSPECIFIED .
+See the NOTES section for the current kernel behavior.)
+.IP (7)
+If the normal root filesystem has a directory
+.IR /initrd ,
+the device
+.I /dev/ram0
+is moved from
+.I /
+to
+.IR /initrd .
+Otherwise, if the directory
+.I /initrd
+does not exist, the device
+.I /dev/ram0
+is unmounted.
+(When moved from
+.I /
+to
+.IR /initrd ,
+.I /dev/ram0
+is not unmounted and therefore processes can remain running from
+.IR /dev/ram0 .
+If directory
+.I /initrd
+does not exist on the normal root filesystem
+and any processes remain running from
+.I /dev/ram0
+when
+.I /linuxrc
+exits, the behavior of the kernel is
+.BR UNSPECIFIED .
+See the NOTES section for the current kernel behavior.)
+.IP (8)
+The usual boot sequence (e.g., invocation of
+.IR /sbin/init )
+is performed on the normal root filesystem.
+.\"
+.\"
+.\"
+.SS Options
+The following boot loader options, when used with
+.BR initrd ,
+affect the kernel's boot-up operation:
+.TP
+.BI initrd= "filename"
+Specifies the file to load as the contents of
+.IR /dev/initrd .
+For
+.B LOADLIN
+this is a command-line option.
+For
+.B LILO
+you have to use this command in the
+.B LILO
+configuration file
+.IR /etc/lilo.config .
+The filename specified with this
+option will typically be a gzipped filesystem image.
+.TP
+.B noinitrd
+This boot option disables the two-phase boot-up operation.
+The kernel performs the usual boot sequence as if
+.I /dev/initrd
+was not initialized.
+With this option, any contents of
+.I /dev/initrd
+loaded into memory by the boot loader contents are preserved.
+This option permits the contents of
+.I /dev/initrd
+to be any data and need not be limited to a filesystem image.
+However, device
+.I /dev/initrd
+is read-only and can be read only one time after system startup.
+.TP
+.BI root= "device-name"
+Specifies the device to be used as the normal root filesystem.
+For
+.B LOADLIN
+this is a command-line option.
+For
+.B LILO
+this is a boot time option or
+can be used as an option line in the
+.B LILO
+configuration file
+.IR /etc/lilo.config .
+The device specified by this option must be a mountable
+device having a suitable root filesystem.
+.\"
+.\"
+.\"
+.SS Changing the normal root filesystem
+By default,
+the kernel's settings
+(e.g., set in the kernel file with
+.BR rdev (8)
+or compiled into the kernel file),
+or the boot loader option setting
+is used for the normal root filesystems.
+For an NFS-mounted normal root filesystem, one has to use the
+.B nfs_root_name
+and
+.B nfs_root_addrs
+boot options to give the NFS settings.
+For more information on NFS-mounted root see the kernel documentation file
+.I Documentation/filesystems/nfs/nfsroot.txt
+.\" commit dc7a08166f3a5f23e79e839a8a88849bd3397c32
+(or
+.I Documentation/filesystems/nfsroot.txt
+before Linux 2.6.33).
+For more information on setting the root filesystem see also the
+.B LILO
+and
+.B LOADLIN
+documentation.
+.P
+It is also possible for the
+.I /linuxrc
+executable to change the normal root device.
+For
+.I /linuxrc
+to change the normal root device,
+.I /proc
+must be mounted.
+After mounting
+.IR /proc ,
+.I /linuxrc
+changes the normal root device by writing into the proc files
+.IR /proc/sys/kernel/real\-root\-dev ,
+.IR /proc/sys/kernel/nfs\-root\-name ,
+and
+.IR /proc/sys/kernel/nfs\-root\-addrs .
+For a physical root device, the root device is changed by having
+.I /linuxrc
+write the new root filesystem device number into
+.IR /proc/sys/kernel/real\-root\-dev .
+For an NFS root filesystem, the root device is changed by having
+.I /linuxrc
+write the NFS setting into files
+.I /proc/sys/kernel/nfs\-root\-name
+and
+.I /proc/sys/kernel/nfs\-root\-addrs
+and then writing 0xff (e.g., the pseudo-NFS-device number) into file
+.IR /proc/sys/kernel/real\-root\-dev .
+For example, the following shell command line would change
+the normal root device to
+.IR /dev/hdb1 :
+.P
+.in +4n
+.EX
+echo 0x365 >/proc/sys/kernel/real\-root\-dev
+.EE
+.in
+.P
+For an NFS example, the following shell command lines would change the
+normal root device to the NFS directory
+.I /var/nfsroot
+on a local networked NFS server with IP number 193.8.232.7 for a system with
+IP number 193.8.232.2 and named "idefix":
+.P
+.in +4n
+.EX
+echo /var/nfsroot >/proc/sys/kernel/nfs\-root\-name
+echo 193.8.232.2:193.8.232.7::255.255.255.0:idefix \e
+    >/proc/sys/kernel/nfs\-root\-addrs
+echo 255 >/proc/sys/kernel/real\-root\-dev
+.EE
+.in
+.P
+.BR Note :
+The use of
+.I /proc/sys/kernel/real\-root\-dev
+to change the root filesystem is obsolete.
+See the Linux kernel source file
+.I Documentation/admin\-guide/initrd.rst
+.\" commit 9d85025b0418163fae079c9ba8f8445212de8568
+(or
+.I Documentation/initrd.txt
+before Linux 4.10)
+as well as
+.BR pivot_root (2)
+and
+.BR pivot_root (8)
+for information on the modern method of changing the root filesystem.
+.\" FIXME . Should this manual page  describe the pivot_root mechanism?
+.\"
+.\"
+.\"
+.SS Usage
+The main motivation for implementing
+.B initrd
+was to allow for modular kernel configuration at system installation.
+.P
+A possible system installation scenario is as follows:
+.IP (1) 5
+The loader program boots from floppy or other media with a minimal kernel
+(e.g., support for
+.IR /dev/ram ,
+.IR /dev/initrd ,
+and the ext2 filesystem) and loads
+.I /dev/initrd
+with a gzipped version of the initial filesystem.
+.IP (2)
+The executable
+.I /linuxrc
+determines what is needed to (1) mount the normal root filesystem
+(i.e., device type, device drivers, filesystem) and (2) the
+distribution media (e.g., CD-ROM, network, tape, ...).
+This can be done by asking the user, by auto-probing,
+or by using a hybrid approach.
+.IP (3)
+The executable
+.I /linuxrc
+loads the necessary modules from the initial root filesystem.
+.IP (4)
+The executable
+.I /linuxrc
+creates and populates the root filesystem.
+(At this stage the normal root filesystem does not have to be a
+completed system yet.)
+.IP (5)
+The executable
+.I /linuxrc
+sets
+.IR /proc/sys/kernel/real\-root\-dev ,
+unmounts
+.IR /proc ,
+the normal root filesystem and any other filesystems
+it has mounted, and then terminates.
+.IP (6)
+The kernel then mounts the normal root filesystem.
+.IP (7)
+Now that the filesystem is accessible and intact,
+the boot loader can be installed.
+.IP (8)
+The boot loader is configured to load into
+.I /dev/initrd
+a filesystem with the set of modules that was used to bring up the system.
+(e.g., device
+.I /dev/ram0
+can be modified, then unmounted, and finally, the image is written from
+.I /dev/ram0
+to a file.)
+.IP (9)
+The system is now bootable and additional installation tasks can be
+performed.
+.P
+The key role of
+.I /dev/initrd
+in the above is to reuse the configuration data during normal system operation
+without requiring initial kernel selection, a large generic kernel or,
+recompiling the kernel.
+.P
+A second scenario is for installations where Linux runs on systems with
+different hardware configurations in a single administrative network.
+In such cases, it may be desirable to use only a small set of kernels
+(ideally only one) and to keep the system-specific part of configuration
+information as small as possible.
+In this case, create a common file
+with all needed modules.
+Then, only the
+.I /linuxrc
+file or a file executed by
+.I /linuxrc
+would be different.
+.P
+A third scenario is more convenient recovery disks.
+Because information like the location of the root filesystem
+partition is not needed at boot time, the system loaded from
+.I /dev/initrd
+can use a dialog and/or auto-detection followed by a
+possible sanity check.
+.P
+Last but not least, Linux distributions on CD-ROM may use
+.B initrd
+for easy installation from the CD-ROM.
+The distribution can use
+.B LOADLIN
+to directly load
+.I /dev/initrd
+from CD-ROM without the need of any floppies.
+The distribution could also use a
+.B LILO
+boot floppy and then bootstrap a bigger RAM disk via
+.I /dev/initrd
+from the CD-ROM.
+.\"
+.\"
+.\"
+.SH FILES
+.I /dev/initrd
+.br
+.I /dev/ram0
+.br
+.I /linuxrc
+.br
+.I /initrd
+.\"
+.\"
+.\"
+.SH NOTES
+.IP \[bu] 3
+With the current kernel, any filesystems that remain mounted when
+.I /dev/ram0
+is moved from
+.I /
+to
+.I /initrd
+continue to be accessible.
+However, the
+.I /proc/mounts
+entries are not updated.
+.IP \[bu]
+With the current kernel, if directory
+.I /initrd
+does not exist, then
+.I /dev/ram0
+will
+.B not
+be fully unmounted if
+.I /dev/ram0
+is used by any process or has any filesystem mounted on it.
+If
+.I /dev/ram0
+is
+.B not
+fully unmounted, then
+.I /dev/ram0
+will remain in memory.
+.IP \[bu]
+Users of
+.I /dev/initrd
+should not depend on the behavior given in the above notes.
+The behavior may change in future versions of the Linux kernel.
+.\"
+.\"
+.\"
+.\" .SH AUTHORS
+.\" The kernel code for device
+.\" .BR initrd
+.\" was written by Werner Almesberger <almesber@lrc.epfl.ch> and
+.\" Hans Lermen <lermen@elserv.ffm.fgan.de>.
+.\" The code for
+.\" .BR initrd
+.\" was added to the baseline Linux kernel in development version 1.3.73.
+.SH SEE ALSO
+.BR chown (1),
+.BR mknod (1),
+.BR ram (4),
+.BR freeramdisk (8),
+.BR rdev (8)
+.P
+.I Documentation/admin\-guide/initrd.rst
+.\" commit 9d85025b0418163fae079c9ba8f8445212de8568
+(or
+.I Documentation/initrd.txt
+before Linux 4.10)
+in the Linux kernel source tree, the LILO documentation,
+the LOADLIN documentation, the SYSLINUX documentation
diff --git a/man/man4/intro.4 b/man/man4/intro.4
new file mode 100644
index 000000000..1a3aadabb
--- /dev/null
+++ b/man/man4/intro.4
@@ -0,0 +1,22 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 16:57:14 1993 by Rik Faith (faith@cs.unc.edu)
+.TH intro 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to special files
+.SH DESCRIPTION
+Section 4 of the manual describes special files (devices).
+.SH FILES
+/dev/* \[em] device files
+.SH NOTES
+.SS Authors and copyright conditions
+Look at the header of the manual page source for the author(s) and copyright
+conditions.
+Note that these can be different from page to page!
+.SH SEE ALSO
+.BR mknod (1),
+.BR mknod (2),
+.BR standards (7)
diff --git a/man/man4/kmem.4 b/man/man4/kmem.4
new file mode 100644
index 000000000..d4c1762c5
--- /dev/null
+++ b/man/man4/kmem.4
@@ -0,0 +1 @@
+.so man4/mem.4
diff --git a/man/man4/lirc.4 b/man/man4/lirc.4
new file mode 100644
index 000000000..ae1caafcf
--- /dev/null
+++ b/man/man4/lirc.4
@@ -0,0 +1,423 @@
+.\" Copyright (c) 2015-2016, Alec Leamas
+.\" Copyright (c) 2018, Sean Young <sean@mess.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH lirc 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lirc \- lirc devices
+.SH DESCRIPTION
+The
+.I /dev/lirc*
+character devices provide a low-level
+bidirectional interface to infra-red (IR) remotes.
+Most of these devices can receive, and some can send.
+When receiving or sending data, the driver works in two different modes
+depending on the underlying hardware.
+.P
+Some hardware (typically TV-cards) decodes the IR signal internally
+and provides decoded button presses as scancode values.
+Drivers for this kind of hardware work in
+.B LIRC_MODE_SCANCODE
+mode.
+Such hardware usually does not support sending IR signals.
+Furthermore, such hardware can only decode a limited set of IR protocols,
+usually only the protocol of the specific remote which is
+bundled with, for example, a TV-card.
+.P
+Other hardware provides a stream of pulse/space durations.
+Such drivers work in
+.B LIRC_MODE_MODE2
+mode.
+Such hardware can be used with (almost) any kind of remote.
+This type of hardware can also be used in
+.B LIRC_MODE_SCANCODE
+mode, in which case the kernel IR decoders will decode the IR.
+These decoders can be written in extended BPF (see
+.BR bpf (2))
+and attached to the
+.B lirc
+device.
+Sometimes, this kind of hardware also supports
+sending IR data.
+.P
+The \fBLIRC_GET_FEATURES\fR ioctl (see below) allows probing for whether
+receiving and sending is supported, and in which modes, amongst other
+features.
+.\"
+.SS Reading input with the LIRC_MODE_MODE2 mode
+In the \fBLIRC_MODE_MODE2 mode\fR, the data returned by
+.BR read (2)
+provides 32-bit values representing a space or a pulse duration.
+The time of the duration (microseconds) is encoded in the lower 24 bits.
+Pulse (also known as flash)
+indicates a duration of infrared light being detected,
+and space (also known as gap) indicates a duration with no infrared.
+If the duration of space exceeds the inactivity timeout,
+a special timeout package is delivered,
+which marks the end of a message.
+The upper 8 bits indicate the type of package:
+.TP 4
+.B LIRC_MODE2_SPACE
+Value reflects a space duration (microseconds).
+.TP 4
+.B LIRC_MODE2_PULSE
+Value reflects a pulse duration (microseconds).
+.TP 4
+.B LIRC_MODE2_FREQUENCY
+Value reflects a frequency (Hz); see the
+.B LIRC_SET_MEASURE_CARRIER_MODE
+ioctl.
+.TP 4
+.B LIRC_MODE2_TIMEOUT
+Value reflects a space duration (microseconds).
+The package reflects a timeout; see the
+.B LIRC_SET_REC_TIMEOUT_REPORTS
+ioctl.
+.\"
+.TP 4
+.B LIRC_MODE2_OVERFLOW
+The IR receiver encountered an overflow,
+and as a result data is missing
+(since Linux 5.18).
+.SS Reading input with the LIRC_MODE_SCANCODE mode
+In the \fBLIRC_MODE_SCANCODE\fR
+mode, the data returned by
+.BR read (2)
+reflects decoded button presses, in the struct \fIlirc_scancode\fR.
+The scancode is stored in the \fIscancode\fR field, and the IR protocol
+is stored in \fIrc_proto\fR.
+This field has one the values of the \fIenum rc_proto\fR.
+.\"
+.SS Writing output with the LIRC_MODE_PULSE mode
+The data written to the character device using
+.BR write (2)
+is a pulse/space sequence of integer values.
+Pulses and spaces are only marked implicitly by their position.
+The data must start and end with a pulse, thus it must always include
+an odd number of samples.
+The
+.BR write (2)
+function blocks until the data has been transmitted by the
+hardware.
+If more data is provided than the hardware can send, the
+.BR write (2)
+call fails with the error
+.BR EINVAL .
+.SS Writing output with the LIRC_MODE_SCANCODE mode
+The data written to the character devices must be a single struct
+\fIlirc_scancode\fR.
+The \fIscancode\fR and \fIrc_proto\fR fields must
+filled in, all other fields must be 0.
+The kernel IR encoders will
+convert the scancode to pulses and spaces.
+The protocol or scancode is invalid, or the
+.B lirc
+device cannot transmit.
+.SH IOCTL COMMANDS
+.nf
+#include <linux/lirc.h>    /* But see BUGS */
+\&
+int ioctl(int fd, int cmd, int *val);
+.fi
+.P
+The following
+.BR ioctl (2)
+operations are provided by the
+.B lirc
+character device to probe or change specific
+.B lirc
+hardware settings.
+.SS Always Supported Commands
+\fI/dev/lirc*\fR devices always support the following commands:
+.TP 4
+.BR LIRC_GET_FEATURES " (\fIvoid\fP)"
+Returns a bit mask of combined features bits; see FEATURES.
+.P
+If a device returns an error code for
+.BR LIRC_GET_FEATURES ,
+it is safe to assume it is not a
+.B lirc
+device.
+.\"
+.SS Optional Commands
+Some
+.B lirc
+devices support the commands listed below.
+Unless otherwise stated, these fail with the error \fBENOTTY\fR if the
+operation isn't supported, or with the error \fBEINVAL\fR if the operation
+failed, or invalid arguments were provided.
+If a driver does not announce support of certain features, invoking
+the corresponding ioctls will fail with the error
+.BR ENOTTY .
+.TP
+.BR LIRC_GET_REC_MODE " (\fIvoid\fP)"
+If the
+.B lirc
+device has no receiver, this operation fails with the error
+.BR ENOTTY .
+Otherwise, it returns the receive mode, which will be one of:
+.RS
+.TP
+.B LIRC_MODE_MODE2
+The driver returns a sequence of pulse/space durations.
+.TP
+.B LIRC_MODE_SCANCODE
+The driver returns struct
+.I lirc_scancode
+values, each of which represents
+a decoded button press.
+.RE
+.TP
+.BR LIRC_SET_REC_MODE " (\fIint\fP)"
+Set the receive mode.
+.I val
+is either
+.B LIRC_MODE_SCANCODE
+or
+.BR LIRC_MODE_MODE2 .
+If the
+.B lirc
+device has no receiver, this operation fails with the error
+.B ENOTTY.
+.TP
+.BR LIRC_GET_SEND_MODE " (\fIvoid\fP)"
+Return the send mode.
+.B LIRC_MODE_PULSE
+or
+.B LIRC_MODE_SCANCODE
+is supported.
+If the
+.B lirc
+device cannot send, this operation fails with the error
+.B ENOTTY.
+.TP
+.BR LIRC_SET_SEND_MODE " (\fIint\fP)"
+Set the send mode.
+.I val
+is either
+.B LIRC_MODE_SCANCODE
+or
+.BR LIRC_MODE_PULSE .
+If the
+.B lirc
+device cannot send, this operation fails with the error
+.BR ENOTTY .
+.TP
+.BR LIRC_SET_SEND_CARRIER " (\fIint\fP)"
+Set the modulation frequency.
+The argument is the frequency (Hz).
+.TP
+.BR LIRC_SET_SEND_DUTY_CYCLE " (\fIint\fP)"
+Set the carrier duty cycle.
+.I val
+is a number in the range [0,100] which
+describes the pulse width as a percentage of the total cycle.
+Currently, no special meaning is defined for 0 or 100, but the values
+are reserved for future use.
+.TP
+.BI LIRC_GET_MIN_TIMEOUT( void )
+.TQ
+.BI LIRC_GET_MAX_TIMEOUT( void )
+Some devices have internal timers that can be used to detect when
+there has been no IR activity for a long time.
+This can help
+.BR lircd (8)
+in detecting that an IR signal is finished and can speed up the
+decoding process.
+These operations
+return integer values with the minimum/maximum timeout that can be
+set (microseconds).
+Some devices have a fixed timeout.
+For such drivers,
+.B LIRC_GET_MIN_TIMEOUT
+and
+.B LIRC_GET_MAX_TIMEOUT
+will fail with the error
+.BR ENOTTY .
+.TP
+.BR LIRC_SET_REC_TIMEOUT " (\fIint\fP)"
+Set the integer value for IR inactivity timeout (microseconds).
+To be accepted, the value must be within the limits defined by
+.B LIRC_GET_MIN_TIMEOUT
+and
+.BR LIRC_GET_MAX_TIMEOUT .
+A value of 0 (if supported by the hardware) disables all hardware
+timeouts and data should be reported as soon as possible.
+If the exact value cannot be set, then the next possible value
+.I greater
+than the given value should be set.
+.TP
+.BR LIRC_GET_REC_TIMEOUT " (\fIvoid\fP)"
+Return the current inactivity timeout (microseconds).
+Available since Linux 4.18.
+.TP
+.BR LIRC_SET_REC_TIMEOUT_REPORTS " (\fIint\fP)"
+Enable
+.RI ( val
+is 1) or disable
+.RI ( val
+is 0) timeout packages in
+.BR LIRC_MODE_MODE2 .
+The behavior of this operation has varied across kernel versions:
+.RS
+.IP \[bu] 3
+Since Linux 5.17:
+timeout packages are always enabled and this ioctl is a no-op.
+.IP \[bu]
+Since Linux 4.16:
+timeout packages are enabled by default.
+Each time the
+.B lirc
+device is opened, the
+.B LIRC_SET_REC_TIMEOUT
+operation can be used to disable (and, if desired, to later re-enable)
+the timeout on the file descriptor.
+.IP \[bu]
+In Linux 4.15 and earlier:
+timeout packages are disabled by default, and enabling them (via
+.BR LIRC_SET_REC_TIMEOUT )
+on any file descriptor associated with the
+.B lirc
+device has the effect of enabling timeouts for all file descriptors
+referring to that device (until timeouts are disabled again).
+.RE
+.TP
+.BR LIRC_SET_REC_CARRIER " (\fIint\fP)"
+Set the upper bound of the receive carrier frequency (Hz).
+See
+.BR LIRC_SET_REC_CARRIER_RANGE .
+.TP
+.BR LIRC_SET_REC_CARRIER_RANGE " (\fIint\fP)"
+Sets the lower bound of the receive carrier frequency (Hz).
+For this to take affect, first set the lower bound using the
+.B LIRC_SET_REC_CARRIER_RANGE
+ioctl, and then the upper bound using the
+.B LIRC_SET_REC_CARRIER
+ioctl.
+.TP
+.BR LIRC_SET_MEASURE_CARRIER_MODE " (\fIint\fP)"
+Enable
+.RI ( val
+is 1) or disable
+.RI ( val
+is 0) the measure mode.
+If enabled, from the next key press on, the driver will send
+.B LIRC_MODE2_FREQUENCY
+packets.
+By default, this should be turned off.
+.TP
+.BR LIRC_GET_REC_RESOLUTION " (\fIvoid\fP)"
+Return the driver resolution (microseconds).
+.TP
+.BR LIRC_SET_TRANSMITTER_MASK " (\fIint\fP)"
+Enable the set of transmitters specified in
+.IR val ,
+which contains a bit mask where each enabled transmitter is a 1.
+The first transmitter is encoded by the least significant bit, and so on.
+When an invalid bit mask is given, for example a bit is set even
+though the device does not have so many transmitters,
+this operation returns the
+number of available transmitters and does nothing otherwise.
+.TP
+.BR LIRC_SET_WIDEBAND_RECEIVER " (\fIint\fP)"
+Some devices are equipped with a special wide band receiver which is
+intended to be used to learn the output of an existing remote.
+This ioctl can be used to enable
+.RI ( val
+equals 1) or disable
+.RI ( val
+equals 0) this functionality.
+This might be useful for devices that otherwise have narrow band
+receivers that prevent them to be used with certain remotes.
+Wide band receivers may also be more precise.
+On the other hand, their disadvantage usually is reduced range of
+reception.
+.IP
+Note: wide band receiver may be implicitly enabled if you enable
+carrier reports.
+In that case, it will be disabled as soon as you disable carrier reports.
+Trying to disable a wide band receiver while carrier reports are active
+will do nothing.
+.\"
+.SH FEATURES
+the
+.B LIRC_GET_FEATURES
+ioctl returns a bit mask describing features of the driver.
+The following bits may be returned in the mask:
+.TP
+.B LIRC_CAN_REC_MODE2
+The driver is capable of receiving using
+.BR LIRC_MODE_MODE2 .
+.TP
+.B LIRC_CAN_REC_SCANCODE
+The driver is capable of receiving using
+.BR LIRC_MODE_SCANCODE .
+.TP
+.B LIRC_CAN_SET_SEND_CARRIER
+The driver supports changing the modulation frequency using
+.BR LIRC_SET_SEND_CARRIER .
+.TP
+.B LIRC_CAN_SET_SEND_DUTY_CYCLE
+The driver supports changing the duty cycle using
+.BR LIRC_SET_SEND_DUTY_CYCLE .
+.TP
+.B LIRC_CAN_SET_TRANSMITTER_MASK
+The driver supports changing the active transmitter(s) using
+.BR LIRC_SET_TRANSMITTER_MASK .
+.TP
+.B LIRC_CAN_SET_REC_CARRIER
+The driver supports setting the receive carrier frequency using
+.BR LIRC_SET_REC_CARRIER .
+Any
+.B lirc
+device since the drivers were merged in Linux 2.6.36
+must have
+.B LIRC_CAN_SET_REC_CARRIER_RANGE
+set if
+.B LIRC_CAN_SET_REC_CARRIER
+feature is set.
+.TP
+.B LIRC_CAN_SET_REC_CARRIER_RANGE
+The driver supports
+.BR LIRC_SET_REC_CARRIER_RANGE .
+The lower bound of the carrier must first be set using the
+.B LIRC_SET_REC_CARRIER_RANGE
+ioctl, before using the
+.B LIRC_SET_REC_CARRIER
+ioctl to set the upper bound.
+.TP
+.B LIRC_CAN_GET_REC_RESOLUTION
+The driver supports
+.BR LIRC_GET_REC_RESOLUTION .
+.TP
+.B LIRC_CAN_SET_REC_TIMEOUT
+The driver supports
+.BR LIRC_SET_REC_TIMEOUT .
+.TP
+.B LIRC_CAN_MEASURE_CARRIER
+The driver supports measuring of the modulation frequency using
+.BR LIRC_SET_MEASURE_CARRIER_MODE .
+.TP
+.B LIRC_CAN_USE_WIDEBAND_RECEIVER
+The driver supports learning mode using
+.BR LIRC_SET_WIDEBAND_RECEIVER .
+.TP
+.B LIRC_CAN_SEND_PULSE
+The driver supports sending using
+.B LIRC_MODE_PULSE
+or
+.B LIRC_MODE_SCANCODE
+.\"
+.SH BUGS
+Using these devices requires the kernel source header file
+.IR lirc.h .
+This file is not available before Linux 4.6.
+Users of older kernels could use the file bundled in
+.UR http://www.lirc.org
+.UE .
+.\"
+.SH SEE ALSO
+\fBir\-ctl\fP(1), \fBlircd\fP(8),\ \fBbpf\fP(2)
+.P
+.UR https://www.kernel.org/\:doc/\:html/\:latest/\:userspace\-api/\:media/\:rc/\:lirc\-dev.html
+.UE
diff --git a/man/man4/loop-control.4 b/man/man4/loop-control.4
new file mode 100644
index 000000000..251e65203
--- /dev/null
+++ b/man/man4/loop-control.4
@@ -0,0 +1 @@
+.so man4/loop.4
diff --git a/man/man4/loop.4 b/man/man4/loop.4
new file mode 100644
index 000000000..253784a34
--- /dev/null
+++ b/man/man4/loop.4
@@ -0,0 +1,361 @@
+.\" Copyright 2002 Urs Thuermann (urs@isnogud.escape.de)
+.\" and Copyright 2015 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH loop 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+loop, loop-control \- loop devices
+.SH SYNOPSIS
+.nf
+#include <linux/loop.h>
+.fi
+.SH DESCRIPTION
+The loop device is a block device that maps its data blocks not to a
+physical device such as a hard disk or optical disk drive,
+but to the blocks of
+a regular file in a filesystem or to another block device.
+This can be useful for example to provide a block device for a filesystem
+image stored in a file, so that it can be mounted with the
+.BR mount (8)
+command.
+You could do
+.P
+.in +4n
+.EX
+$ \fBdd if=/dev/zero of=file.img bs=1MiB count=10\fP
+$ \fBsudo losetup /dev/loop4 file.img\fP
+$ \fBsudo mkfs \-t ext4 /dev/loop4\fP
+$ \fBsudo mkdir /myloopdev\fP
+$ \fBsudo mount /dev/loop4 /myloopdev\fP
+.EE
+.in
+.P
+See
+.BR losetup (8)
+for another example.
+.P
+A transfer function can be specified for each loop device for
+encryption and decryption purposes.
+.P
+The following
+.BR ioctl (2)
+operations are provided by the loop block device:
+.TP
+.B LOOP_SET_FD
+Associate the loop device with the open file whose file descriptor is
+passed as the (third)
+.BR ioctl (2)
+argument.
+.TP
+.B LOOP_CLR_FD
+Disassociate the loop device from any file descriptor.
+.TP
+.B LOOP_SET_STATUS
+Set the status of the loop device using the (third)
+.BR ioctl (2)
+argument.
+This argument is a pointer to a
+.I loop_info
+structure, defined in
+.I <linux/loop.h>
+as:
+.IP
+.in +4n
+.EX
+struct loop_info {
+    int           lo_number;      /* ioctl r/o */
+    dev_t         lo_device;      /* ioctl r/o */
+    unsigned long lo_inode;       /* ioctl r/o */
+    dev_t         lo_rdevice;     /* ioctl r/o */
+    int           lo_offset;
+    int           lo_encrypt_type;
+    int           lo_encrypt_key_size;  /* ioctl w/o */
+    int           lo_flags;       /* ioctl r/w (r/o before
+                                     Linux 2.6.25) */
+    char          lo_name[LO_NAME_SIZE];
+    unsigned char lo_encrypt_key[LO_KEY_SIZE];
+                                  /* ioctl w/o */
+    unsigned long lo_init[2];
+    char          reserved[4];
+};
+.EE
+.in
+.IP
+The encryption type
+.RI ( lo_encrypt_type )
+should be one of
+.BR LO_CRYPT_NONE ,
+.BR LO_CRYPT_XOR ,
+.BR LO_CRYPT_DES ,
+.BR LO_CRYPT_FISH2 ,
+.BR LO_CRYPT_BLOW ,
+.BR LO_CRYPT_CAST128 ,
+.BR LO_CRYPT_IDEA ,
+.BR LO_CRYPT_DUMMY ,
+.BR LO_CRYPT_SKIPJACK ,
+or (since Linux 2.6.0)
+.BR LO_CRYPT_CRYPTOAPI .
+.IP
+The
+.I lo_flags
+field is a bit mask that can include zero or more of the following:
+.RS
+.TP
+.B LO_FLAGS_READ_ONLY
+The loopback device is read-only.
+.TP
+.BR LO_FLAGS_AUTOCLEAR " (since Linux 2.6.25)"
+.\" commit 96c5865559cee0f9cbc5173f3c949f6ce3525581
+The loopback device will autodestruct on last close.
+.TP
+.BR LO_FLAGS_PARTSCAN " (since Linux 3.2)"
+.\" commit e03c8dd14915fabc101aa495828d58598dc5af98
+Allow automatic partition scanning.
+.TP
+.BR LO_FLAGS_DIRECT_IO " (since Linux 4.10)"
+.\" commit 2e5ab5f379f96a6207c45be40c357ebb1beb8ef3
+Use direct I/O mode to access the backing file.
+.RE
+.IP
+The only
+.I lo_flags
+that can be modified by
+.B LOOP_SET_STATUS
+are
+.B LO_FLAGS_AUTOCLEAR
+and
+.BR LO_FLAGS_PARTSCAN .
+.TP
+.B LOOP_GET_STATUS
+Get the status of the loop device.
+The (third)
+.BR ioctl (2)
+argument must be a pointer to a
+.IR "struct loop_info" .
+.TP
+.BR LOOP_CHANGE_FD " (since Linux 2.6.5)"
+Switch the backing store of the loop device to the new file identified
+file descriptor specified in the (third)
+.BR ioctl (2)
+argument, which is an integer.
+This operation is possible only if the loop device is read-only and
+the new backing store is the same size and type as the old backing store.
+.TP
+.BR LOOP_SET_CAPACITY " (since Linux 2.6.30)"
+.\" commit 53d6660836f233df66490707365ab177e5fb2bb4
+Resize a live loop device.
+One can change the size of the underlying backing store and then use this
+operation so that the loop driver learns about the new size.
+This operation takes no argument.
+.TP
+.BR LOOP_SET_DIRECT_IO " (since Linux 4.10)"
+.\" commit ab1cb278bc7027663adbfb0b81404f8398437e11
+Set DIRECT I/O mode on the loop device, so that
+it can be used to open backing file.
+The (third)
+.BR ioctl (2)
+argument is an unsigned long value.
+A nonzero represents direct I/O mode.
+.TP
+.BR LOOP_SET_BLOCK_SIZE " (since Linux 4.14)"
+.\" commit 89e4fdecb51cf5535867026274bc97de9480ade5
+Set the block size of the loop device.
+The (third)
+.BR ioctl (2)
+argument is an unsigned long value.
+This value must be a power of two in the range
+[512,pagesize];
+otherwise, an
+.B EINVAL
+error results.
+.TP
+.BR LOOP_CONFIGURE " (since Linux 5.8)"
+.\" commit 3448914e8cc550ba792d4ccc74471d1ca4293aae
+Setup and configure all loop device parameters in a single step using
+the (third)
+.BR ioctl (2)
+argument.
+This argument is a pointer to a
+.I loop_config
+structure, defined in
+.I <linux/loop.h>
+as:
+.IP
+.in +4n
+.EX
+struct loop_config {
+    __u32               fd;
+    __u32               block_size;
+    struct loop_info64  info;
+    __u64               __reserved[8];
+};
+.EE
+.in
+.IP
+In addition to doing what
+.B LOOP_SET_STATUS
+can do,
+.B LOOP_CONFIGURE
+can also be used to do the following:
+.RS
+.IP \[bu] 3
+set the correct block size immediately by setting
+.IR loop_config.block_size ;
+.IP \[bu]
+explicitly request direct I/O mode by setting
+.B LO_FLAGS_DIRECT_IO
+in
+.IR loop_config.info.lo_flags ;
+and
+.IP \[bu]
+explicitly request read-only mode by setting
+.B LO_FLAGS_READ_ONLY
+in
+.IR loop_config.info.lo_flags .
+.RE
+.P
+Since Linux 2.6, there are two new
+.BR ioctl (2)
+operations:
+.TP
+.B LOOP_SET_STATUS64
+.TQ
+.B LOOP_GET_STATUS64
+These are similar to
+.BR LOOP_SET_STATUS " and " LOOP_GET_STATUS
+described above but use the
+.I loop_info64
+structure,
+which has some additional fields and a larger range for some other fields:
+.IP
+.in +4n
+.EX
+struct loop_info64 {
+    uint64_t lo_device;           /* ioctl r/o */
+    uint64_t lo_inode;            /* ioctl r/o */
+    uint64_t lo_rdevice;          /* ioctl r/o */
+    uint64_t lo_offset;
+    uint64_t lo_sizelimit;  /* bytes, 0 == max available */
+    uint32_t lo_number;           /* ioctl r/o */
+    uint32_t lo_encrypt_type;
+    uint32_t lo_encrypt_key_size; /* ioctl w/o */
+    uint32_t lo_flags; i          /* ioctl r/w (r/o before
+                                     Linux 2.6.25) */
+    uint8_t  lo_file_name[LO_NAME_SIZE];
+    uint8_t  lo_crypt_name[LO_NAME_SIZE];
+    uint8_t  lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
+    uint64_t lo_init[2];
+};
+.EE
+.in
+.SS /dev/loop-control
+Since Linux 3.1,
+.\" commit 770fe30a46a12b6fb6b63fbe1737654d28e84844
+the kernel provides the
+.I /dev/loop\-control
+device, which permits an application to dynamically find a free device,
+and to add and remove loop devices from the system.
+To perform these operations, one first opens
+.I /dev/loop\-control
+and then employs one of the following
+.BR ioctl (2)
+operations:
+.TP
+.B LOOP_CTL_GET_FREE
+Allocate or find a free loop device for use.
+On success, the device number is returned as the result of the call.
+This operation takes no argument.
+.TP
+.B LOOP_CTL_ADD
+Add the new loop device whose device number is specified
+as a long integer in the third
+.BR ioctl (2)
+argument.
+On success, the device index is returned as the result of the call.
+If the device is already allocated, the call fails with the error
+.BR EEXIST .
+.TP
+.B LOOP_CTL_REMOVE
+Remove the loop device whose device number is specified
+as a long integer in the third
+.BR ioctl (2)
+argument.
+On success, the device number is returned as the result of the call.
+If the device is in use, the call fails with the error
+.BR EBUSY .
+.SH FILES
+.TP
+.I /dev/loop*
+The loop block special device files.
+.SH EXAMPLES
+The program below uses the
+.I /dev/loop\-control
+device to find a free loop device, opens the loop device,
+opens a file to be used as the underlying storage for the device,
+and then associates the loop device with the backing store.
+The following shell session demonstrates the use of the program:
+.P
+.in +4n
+.EX
+$ \fBdd if=/dev/zero of=file.img bs=1MiB count=10\fP
+10+0 records in
+10+0 records out
+10485760 bytes (10 MB) copied, 0.00609385 s, 1.7 GB/s
+$ \fBsudo ./mnt_loop file.img\fP
+loopname = /dev/loop5
+.EE
+.in
+.SS Program source
+\&
+.EX
+#include <fcntl.h>
+#include <linux/loop.h>
+#include <sys/ioctl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \e
+                        } while (0)
+\&
+int
+main(int argc, char *argv[])
+{
+    int loopctlfd, loopfd, backingfile;
+    long devnr;
+    char loopname[4096];
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s backing\-file\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    loopctlfd = open("/dev/loop\-control", O_RDWR);
+    if (loopctlfd == \-1)
+        errExit("open: /dev/loop\-control");
+\&
+    devnr = ioctl(loopctlfd, LOOP_CTL_GET_FREE);
+    if (devnr == \-1)
+        errExit("ioctl\-LOOP_CTL_GET_FREE");
+\&
+    sprintf(loopname, "/dev/loop%ld", devnr);
+    printf("loopname = %s\en", loopname);
+\&
+    loopfd = open(loopname, O_RDWR);
+    if (loopfd == \-1)
+        errExit("open: loopname");
+\&
+    backingfile = open(argv[1], O_RDWR);
+    if (backingfile == \-1)
+        errExit("open: backing\-file");
+\&
+    if (ioctl(loopfd, LOOP_SET_FD, backingfile) == \-1)
+        errExit("ioctl\-LOOP_SET_FD");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR losetup (8),
+.BR mount (8)
diff --git a/man/man4/lp.4 b/man/man4/lp.4
new file mode 100644
index 000000000..d472b7cbd
--- /dev/null
+++ b/man/man4/lp.4
@@ -0,0 +1,137 @@
+'\" t
+.\" Copyright (c) Michael Haardt (michael@cantor.informatik.rwth-aachen.de),
+.\"     Sun Jan 15 19:16:33 1995
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified, Sun Feb 26 15:02:58 1995, faith@cs.unc.edu
+.TH lp 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+lp \- line printer devices
+.SH SYNOPSIS
+.nf
+.B #include <linux/lp.h>
+.fi
+.SH CONFIGURATION
+\fBlp\fP[0\[en]2] are character devices for the parallel line printers;
+they have major number 6 and minor number 0\[en]2.
+The minor numbers
+correspond to the printer port base addresses 0x03bc, 0x0378, and 0x0278.
+Usually they have mode 220 and are owned by user
+.I root
+and group
+.IR lp .
+You can use printer ports either with polling or with interrupts.
+Interrupts are recommended when high traffic is expected, for example,
+for laser printers.
+For typical dot matrix printers, polling will usually be enough.
+The default is polling.
+.SH DESCRIPTION
+The following
+.BR ioctl (2)
+calls are supported:
+.TP
+.BR "int ioctl(int " fd ", LPTIME, int " arg )
+Sets the amount of time that the driver sleeps before rechecking the printer
+when the printer's buffer appears to be filled to
+.IR arg .
+If you have a fast printer, decrease this number;
+if you have a slow printer, then increase it.
+This is in hundredths of a second, the default 2
+being 0.02 seconds.
+It influences only the polling driver.
+.TP
+.BR "int ioctl(int " fd ", LPCHAR, int " arg )
+Sets the maximum number of busy-wait iterations which the polling driver does
+while waiting for the printer to get ready for receiving a character to
+.IR arg .
+If printing is too slow, increase this number; if the
+system gets too slow, decrease this number.
+The default is 1000.
+It influences only the polling driver.
+.TP
+.BR "int ioctl(int " fd ", LPABORT, int " arg )
+If
+.I arg
+is 0, the printer driver will retry on errors, otherwise
+it will abort.
+The default is 0.
+.TP
+.BR "int ioctl(int " fd ", LPABORTOPEN, int " arg )
+If
+.I arg
+is 0,
+.BR open (2)
+will be aborted on error, otherwise error will be ignored.
+The default is to ignore it.
+.TP
+.BR "int ioctl(int " fd ", LPCAREFUL, int " arg )
+If
+.I arg
+is 0, then the out-of-paper, offline, and error signals are
+required to be false on all writes, otherwise they are ignored.
+The default is to ignore them.
+.TP
+.BR "int ioctl(int " fd ", LPWAIT, int " arg )
+Sets the number of busy waiting iterations to wait before strobing the
+printer to accept a just-written character, and the number of iterations to
+wait before turning the strobe off again,
+to
+.IR arg .
+The specification says this time should be 0.5
+microseconds, but experience has shown the delay caused by the code is
+already enough.
+For that reason, the default value is 0.
+.\" FIXME . Actually, since Linux 2.2, the default is 1
+This is used for both the polling and the interrupt driver.
+.TP
+.BR "int ioctl(int " fd ", LPSETIRQ, int " arg )
+This
+.BR ioctl (2)
+requires superuser privileges.
+It takes an
+.I int
+containing the new IRQ as argument.
+As a side effect, the printer will be reset.
+When
+.I arg
+is 0, the polling driver will be used, which is also default.
+.TP
+.BR "int ioctl(int " fd ", LPGETIRQ, int *" arg )
+Stores the currently used IRQ in
+.IR arg .
+.TP
+.BR "int ioctl(int " fd ", LPGETSTATUS, int *" arg )
+Stores the value of the status port in
+.IR arg .
+The bits have the following meaning:
+.TS
+l l.
+LP_PBUSY	inverted busy input, active high
+LP_PACK	unchanged acknowledge input, active low
+LP_POUTPA	unchanged out-of-paper input, active high
+LP_PSELECD	unchanged selected input, active high
+LP_PERRORP	unchanged error input, active low
+.TE
+.IP
+Refer to your printer manual for the meaning of the signals.
+Note that undocumented bits may also be set, depending on your printer.
+.TP
+.BR "int ioctl(int " fd ", LPRESET)"
+Resets the printer.
+No argument is used.
+.SH FILES
+.I /dev/lp*
+.\" .SH AUTHORS
+.\" The printer driver was originally written by Jim Weigand and Linus
+.\" Torvalds.
+.\" It was further improved by Michael K.\& Johnson.
+.\" The interrupt code was written by Nigel Gamble.
+.\" Alan Cox modularized it.
+.\" LPCAREFUL, LPABORT, LPGETSTATUS were added by Chris Metcalf.
+.SH SEE ALSO
+.BR chmod (1),
+.BR chown (1),
+.BR mknod (1),
+.BR lpcntl (8),
+.BR tunelp (8)
diff --git a/man/man4/mem.4 b/man/man4/mem.4
new file mode 100644
index 000000000..5bc14bbb6
--- /dev/null
+++ b/man/man4/mem.4
@@ -0,0 +1,81 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 16:59:10 1993 by Rik Faith (faith@cs.unc.edu)
+.TH mem 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mem, kmem, port \- system memory, kernel memory and system ports
+.SH DESCRIPTION
+.I /dev/mem
+is a character device file
+that is an image of the main memory of the computer.
+It may be used, for example, to examine (and even patch) the system.
+.P
+Byte addresses in
+.I /dev/mem
+are interpreted as physical memory addresses.
+References to nonexistent locations cause errors to be returned.
+.P
+Examining and patching is likely to lead to unexpected results
+when read-only or write-only bits are present.
+.P
+Since Linux 2.6.26, and depending on the architecture, the
+.B CONFIG_STRICT_DEVMEM
+kernel configuration option limits the areas
+which can be accessed through this file.
+For example: on x86, RAM access is not allowed but accessing
+memory-mapped PCI regions is.
+.P
+It is typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 660 /dev/mem c 1 1
+chown root:kmem /dev/mem
+.EE
+.in
+.P
+The file
+.I /dev/kmem
+is the same as
+.IR /dev/mem ,
+except that the kernel virtual memory
+rather than physical memory is accessed.
+Since Linux 2.6.26, this file is available only if the
+.B CONFIG_DEVKMEM
+kernel configuration option is enabled.
+.P
+It is typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 640 /dev/kmem c 1 2
+chown root:kmem /dev/kmem
+.EE
+.in
+.P
+.I /dev/port
+is similar to
+.IR /dev/mem ,
+but the I/O ports are accessed.
+.P
+It is typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 660 /dev/port c 1 4
+chown root:kmem /dev/port
+.EE
+.in
+.SH FILES
+.I /dev/mem
+.br
+.I /dev/kmem
+.br
+.I /dev/port
+.SH SEE ALSO
+.BR chown (1),
+.BR mknod (1),
+.BR ioperm (2)
diff --git a/man/man4/mouse.4 b/man/man4/mouse.4
new file mode 100644
index 000000000..1a08c15d8
--- /dev/null
+++ b/man/man4/mouse.4
@@ -0,0 +1,171 @@
+'\" t
+.\" This manpage is Copyright (C) 1996 Michael Haardt.
+.\" Updates Nov 1998, Andries Brouwer
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH mouse 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mouse \- serial mouse interface
+.SH CONFIGURATION
+Serial mice are connected to a serial RS232/V24 dialout line, see
+.BR ttyS (4)
+for a description.
+.SH DESCRIPTION
+.SS Introduction
+The pinout of the usual 9 pin plug as used for serial mice is:
+.P
+.TS
+center;
+r c l.
+pin	name	used for
+2	RX	Data
+3	TX	\-12 V, Imax = 10 mA
+4	DTR	+12 V, Imax = 10 mA
+7	RTS	+12 V, Imax = 10 mA
+5	GND	Ground
+.TE
+.P
+This is the specification, in fact 9 V suffices with most mice.
+.P
+The mouse driver can recognize a mouse by dropping RTS to low and raising
+it again.
+About 14 ms later the mouse will send 0x4D (\[aq]M\[aq]) on the data line.
+After a further 63 ms, a Microsoft-compatible 3-button mouse will send
+0x33 (\[aq]3\[aq]).
+.P
+The relative mouse movement is sent as
+.I dx
+(positive means right)
+and
+.I dy
+(positive means down).
+Various mice can operate at different speeds.
+To select speeds, cycle through the
+speeds 9600, 4800, 2400, and 1200 bit/s, each time writing the two characters
+from the table below and waiting 0.1 seconds.
+The following table shows available speeds and the strings that select them:
+.P
+.TS
+center;
+l l.
+bit/s	string
+9600	*q
+4800	*p
+2400	*o
+1200	*n
+.TE
+.P
+The first byte of a data packet can be used for synchronization purposes.
+.SS Microsoft protocol
+The
+.B Microsoft
+protocol uses 1 start bit, 7 data bits, no parity
+and one stop bit at the speed of 1200 bits/sec.
+Data is sent to RxD in 3-byte packets.
+The
+.I dx
+and
+.I dy
+movements are sent as
+two's-complement,
+.I lb
+.RI ( rb )
+are set when the left (right)
+button is pressed:
+.P
+.TS
+center;
+r c c c c c c c.
+byte	d6	d5	d4	d3	d2	d1	d0
+1	1	lb	rb	dy7	dy6	dx7	dx6
+2	0	dx5	dx4	dx3	dx2	dx1	dx0
+3	0	dy5	dy4	dy3	dy2	dy1	dy0
+.TE
+.SS 3-button Microsoft protocol
+Original Microsoft mice only have two buttons.
+However, there are some
+three button mice which also use the Microsoft protocol.
+Pressing or
+releasing the middle button is reported by sending a packet with zero
+movement and no buttons pressed.
+(Thus, unlike for the other two buttons, the status of the middle
+button is not reported in each packet.)
+.SS Logitech protocol
+Logitech serial 3-button mice use a different extension of the
+Microsoft protocol: when the middle button is up, the above 3-byte
+packet is sent.
+When the middle button is down a 4-byte packet is
+sent, where the 4th byte has value 0x20 (or at least has the 0x20
+bit set).
+In particular, a press of the middle button is reported
+as 0,0,0,0x20 when no other buttons are down.
+.SS Mousesystems protocol
+The
+.B Mousesystems
+protocol uses 1 start bit, 8 data bits, no parity,
+and two stop bits at the speed of 1200 bits/sec.
+Data is sent to RxD in
+5-byte packets.
+.I dx
+is sent as the sum of the two two's-complement
+values,
+.I dy
+is send as negated sum of the two two's-complement
+values.
+.I lb
+.RI ( mb ,
+.IR rb )
+are cleared when the left (middle,
+right) button is pressed:
+.P
+.TS
+center;
+r c c c c c c c c.
+byte	d7	d6	d5	d4	d3	d2	d1	d0
+1	1	0	0	0	0	lb	mb	rb
+2	0	dxa6	dxa5	dxa4	dxa3	dxa2	dxa1	dxa0
+3	0	dya6	dya5	dya4	dya3	dya2	dya1	dya0
+4	0	dxb6	dxb5	dxb4	dxb3	dxb2	dxb1	dxb0
+5	0	dyb6	dyb5	dyb4	dyb3	dyb2	dyb1	dyb0
+.TE
+.P
+Bytes 4 and 5 describe the change that occurred since bytes 2 and 3
+were transmitted.
+.SS Sun protocol
+The
+.B Sun
+protocol is the 3-byte version of the above 5-byte
+Mousesystems protocol: the last two bytes are not sent.
+.SS MM protocol
+The
+.B MM
+protocol uses 1 start bit, 8 data bits, odd parity, and one
+stop bit at the speed of 1200 bits/sec.
+Data is sent to RxD in 3-byte
+packets.
+.I dx
+and
+.I dy
+are sent as single signed values, the
+sign bit indicating a negative value.
+.I lb
+.RI ( mb ,
+.IR rb )
+are
+set when the left (middle, right) button is pressed:
+.P
+.TS
+center;
+r c c c c c c c c.
+byte	d7	d6	d5	d4	d3	d2	d1	d0
+1	1	0	0	dxs	dys	lb	mb	rb
+2	0	dx6	dx5	dx4	dx3	dx2	dx1	dx0
+3	0	dy6	dy5	dy4	dy3	dy2	dy1	dy0
+.TE
+.SH FILES
+.TP
+.I /dev/mouse
+A commonly used symbolic link pointing to a mouse device.
+.SH SEE ALSO
+.BR ttyS (4),
+.BR gpm (8)
diff --git a/man/man4/msr.4 b/man/man4/msr.4
new file mode 100644
index 000000000..d6b859e1b
--- /dev/null
+++ b/man/man4/msr.4
@@ -0,0 +1,42 @@
+.\" Copyright (c) 2009 Intel Corporation, Author Andi Kleen
+.\" Some sentences copied from comments in arch/x86/kernel/msr.c
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH msr 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+msr \- x86 CPU MSR access device
+.SH DESCRIPTION
+.I /dev/cpu/CPUNUM/msr
+provides an interface to read and write the model-specific
+registers (MSRs) of an x86 CPU.
+.I CPUNUM
+is the number of the CPU to access as listed in
+.IR /proc/cpuinfo .
+.P
+The register access is done by opening the file and seeking
+to the MSR number as offset in the file, and then
+reading or writing in chunks of 8 bytes.
+An I/O transfer of more than 8 bytes means multiple reads or writes
+of the same register.
+.P
+This file is protected so that it can be read and written only by the user
+.IR root ,
+or members of the group
+.IR root .
+.SH NOTES
+The
+.I msr
+driver is not auto-loaded.
+On modular kernels you might need to use the following command
+to load it explicitly before use:
+.P
+.in +4n
+.EX
+$ modprobe msr
+.EE
+.in
+.SH SEE ALSO
+Intel Corporation Intel 64 and IA-32 Architectures
+Software Developer's Manual Volume 3B Appendix B,
+for an overview of the Intel CPU MSRs.
diff --git a/man/man4/null.4 b/man/man4/null.4
new file mode 100644
index 000000000..b31c96ec5
--- /dev/null
+++ b/man/man4/null.4
@@ -0,0 +1,52 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:00:12 1993 by Rik Faith (faith@cs.unc.edu)
+.TH null 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+null, zero \- data sink
+.SH DESCRIPTION
+Data written to the
+.I /dev/null
+and
+.I /dev/zero
+special files is discarded.
+.P
+Reads from
+.I /dev/null
+always return end of file (i.e.,
+.BR read (2)
+returns 0), whereas reads from
+.I /dev/zero
+always return bytes containing zero (\[aq]\e0\[aq] characters).
+.P
+These devices are typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 666 /dev/null c 1 3
+mknod \-m 666 /dev/zero c 1 5
+chown root:root /dev/null /dev/zero
+.EE
+.in
+.SH FILES
+.I /dev/null
+.br
+.I /dev/zero
+.SH NOTES
+If these devices are not writable and readable for all users, many
+programs will act strangely.
+.P
+Since Linux 2.6.31,
+.\" commit 2b83868723d090078ac0e2120e06a1cc94dbaef0
+reads from
+.I /dev/zero
+are interruptible by signals.
+(This change was made to help with bad latencies for large reads from
+.IR /dev/zero .)
+.SH SEE ALSO
+.BR chown (1),
+.BR mknod (1),
+.BR full (4)
diff --git a/man/man4/port.4 b/man/man4/port.4
new file mode 100644
index 000000000..d4c1762c5
--- /dev/null
+++ b/man/man4/port.4
@@ -0,0 +1 @@
+.so man4/mem.4
diff --git a/man/man4/ptmx.4 b/man/man4/ptmx.4
new file mode 100644
index 000000000..b50d4e710
--- /dev/null
+++ b/man/man4/ptmx.4
@@ -0,0 +1 @@
+.so man4/pts.4
diff --git a/man/man4/pts.4 b/man/man4/pts.4
new file mode 100644
index 000000000..3afff788e
--- /dev/null
+++ b/man/man4/pts.4
@@ -0,0 +1,75 @@
+.\" This man page was written by Jeremy Phelps <jphelps@notreached.net>.
+.\" Notes added - aeb
+.\"
+.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE)
+.\" Redistribute and revise at will.
+.\" %%%LICENSE_END
+.\"
+.TH pts 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ptmx, pts \- pseudoterminal master and slave
+.SH DESCRIPTION
+The file
+.I /dev/ptmx
+(the pseudoterminal multiplexor device)
+is a character file with major number 5 and
+minor number 2, usually with mode 0666 and ownership root:root.
+It is used to create a pseudoterminal master and slave pair.
+.P
+When a process opens
+.IR /dev/ptmx ,
+it gets a file
+descriptor for a pseudoterminal master
+and a pseudoterminal slave device is created in the
+.I /dev/pts
+directory.
+Each file descriptor obtained by opening
+.I /dev/ptmx
+is an independent pseudoterminal master with its own associated slave,
+whose path can
+be found by passing the file descriptor to
+.BR ptsname (3).
+.P
+Before opening the pseudoterminal slave, you must pass the master's file
+descriptor to
+.BR grantpt (3)
+and
+.BR unlockpt (3).
+.P
+Once both the pseudoterminal master and slave are open, the slave provides
+processes with an interface that is identical to that of a real terminal.
+.P
+Data written to the slave is presented on the master file descriptor as input.
+Data written to the master is presented to the slave as input.
+.P
+In practice, pseudoterminals are used for implementing terminal emulators
+such as
+.BR xterm (1),
+in which data read from the pseudoterminal master is interpreted by the
+application in the same way
+a real terminal would interpret the data, and for implementing remote-login
+programs such as
+.BR sshd (8),
+in which data read from the pseudoterminal master is sent across the network
+to a client program that is connected to a terminal or terminal emulator.
+.P
+Pseudoterminals can also be used to send input to programs that normally
+refuse to read input from pipes (such as
+.BR su (1),
+and
+.BR passwd (1)).
+.SH FILES
+.IR /dev/ptmx ,
+.I /dev/pts/*
+.SH NOTES
+The Linux support for the above (known as UNIX 98 pseudoterminal naming)
+is done using the
+.I devpts
+filesystem, which should be mounted on
+.IR /dev/pts .
+.SH SEE ALSO
+.BR getpt (3),
+.BR grantpt (3),
+.BR ptsname (3),
+.BR unlockpt (3),
+.BR pty (7)
diff --git a/man/man4/ram.4 b/man/man4/ram.4
new file mode 100644
index 000000000..0f9bddc92
--- /dev/null
+++ b/man/man4/ram.4
@@ -0,0 +1,28 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:01:11 1993 by Rik Faith (faith@cs.unc.edu)
+.TH ram 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ram \- ram disk device
+.SH DESCRIPTION
+The
+.I ram
+device is a block device to access the ram disk in raw mode.
+.P
+It is typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 660 /dev/ram b 1 1
+chown root:disk /dev/ram
+.EE
+.in
+.SH FILES
+.I /dev/ram
+.SH SEE ALSO
+.BR chown (1),
+.BR mknod (1),
+.BR mount (8)
diff --git a/man/man4/random.4 b/man/man4/random.4
new file mode 100644
index 000000000..1d463254d
--- /dev/null
+++ b/man/man4/random.4
@@ -0,0 +1,349 @@
+.\" Copyright (c) 1997 John S. Kallal (kallal@voicenet.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Some changes by tytso and aeb.
+.\"
+.\" 2004-12-16, John V. Belmonte/mtk, Updated init and quit scripts
+.\" 2004-04-08, AEB, Improved description of read from /dev/urandom
+.\" 2008-06-20, George Spelvin <linux@horizon.com>,
+.\"             Matt Mackall <mpm@selenic.com>
+.\"
+.TH random 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+random, urandom \- kernel random number source devices
+.SH SYNOPSIS
+.nf
+#include <linux/random.h>
+.P
+.BI "int ioctl(" fd ", RND" request ", " param ");"
+.fi
+.SH DESCRIPTION
+The character special files \fI/dev/random\fP and
+\fI/dev/urandom\fP (present since Linux 1.3.30)
+provide an interface to the kernel's random number generator.
+The file
+.I /dev/random
+has major device number 1 and minor device number 8.
+The file
+.I /dev/urandom
+has major device number 1 and minor device number 9.
+.P
+The random number generator gathers environmental noise
+from device drivers and other sources into an entropy pool.
+The generator also keeps an estimate of the
+number of bits of noise in the entropy pool.
+From this entropy pool, random numbers are created.
+.P
+Linux 3.17 and later provides the simpler and safer
+.BR getrandom (2)
+interface which requires no special files;
+see the
+.BR getrandom (2)
+manual page for details.
+.P
+When read, the
+.I /dev/urandom
+device returns random bytes using a pseudorandom
+number generator seeded from the entropy pool.
+Reads from this device do not block (i.e., the CPU is not yielded),
+but can incur an appreciable delay when requesting large amounts of data.
+.P
+When read during early boot time,
+.I /dev/urandom
+may return data prior to the entropy pool being initialized.
+.\" This is a real problem; see
+.\" commit 9b4d008787f864f17d008c9c15bbe8a0f7e2fc24
+If this is of concern in your application, use
+.BR getrandom (2)
+or \fI/dev/random\fP instead.
+.P
+The \fI/dev/random\fP device is a legacy interface which dates back to
+a time where the cryptographic primitives used in the implementation
+of \fI/dev/urandom\fP were not widely trusted.
+It will return random bytes only within the estimated number of
+bits of fresh noise in the entropy pool, blocking if necessary.
+\fI/dev/random\fP is suitable for applications that need
+high quality randomness, and can afford indeterminate delays.
+.P
+When the entropy pool is empty, reads from \fI/dev/random\fP will block
+until additional environmental noise is gathered.
+Since Linux 5.6, the
+.B O_NONBLOCK
+flag is ignored as
+.I /dev/random
+will no longer block except during early boot process.
+In earlier versions, if
+.BR open (2)
+is called for
+.I /dev/random
+with the
+.B O_NONBLOCK
+flag, a subsequent
+.BR read (2)
+will not block if the requested number of bytes is not available.
+Instead, the available bytes are returned.
+If no byte is available,
+.BR read (2)
+will return \-1 and
+.I errno
+will be set to
+.BR EAGAIN .
+.P
+The
+.B O_NONBLOCK
+flag has no effect when opening
+.IR /dev/urandom .
+When calling
+.BR read (2)
+for the device
+.IR /dev/urandom ,
+reads of up to 256 bytes will return as many bytes as are requested
+and will not be interrupted by a signal handler.
+Reads with a buffer over this limit may return less than the
+requested number of bytes or fail with the error
+.BR EINTR ,
+if interrupted by a signal handler.
+.P
+Since Linux 3.16,
+.\" commit 79a8468747c5f95ed3d5ce8376a3e82e0c5857fc
+a
+.BR read (2)
+from
+.I /dev/urandom
+will return at most 32\ MB.
+A
+.BR read (2)
+from
+.I /dev/random
+will return at most 512 bytes
+.\" SEC_XFER_SIZE in drivers/char/random.c
+(340 bytes before Linux 2.6.12).
+.P
+Writing to \fI/dev/random\fP or \fI/dev/urandom\fP will update the
+entropy pool with the data written, but this will not result in a
+higher entropy count.
+This means that it will impact the contents
+read from both files, but it will not make reads from
+\fI/dev/random\fP faster.
+.SS Usage
+The
+.I /dev/random
+interface is considered a legacy interface, and
+.I /dev/urandom
+is preferred and sufficient in all use cases, with the exception of
+applications which require randomness during early boot time; for
+these applications,
+.BR getrandom (2)
+must be used instead,
+because it will block until the entropy pool is initialized.
+.P
+If a seed file is saved across reboots as recommended below,
+the output is
+cryptographically secure against attackers without local root access as
+soon as it is reloaded in the boot sequence, and perfectly adequate for
+network encryption session keys.
+(All major Linux distributions have saved the seed file across reboots
+since 2000 at least.)
+Since reads from
+.I /dev/random
+may block, users will usually want to open it in nonblocking mode
+(or perform a read with timeout),
+and provide some sort of user notification if the desired
+entropy is not immediately available.
+.\"
+.SS Configuration
+If your system does not have
+\fI/dev/random\fP and \fI/dev/urandom\fP created already, they
+can be created with the following commands:
+.P
+.in +4n
+.EX
+mknod \-m 666 /dev/random c 1 8
+mknod \-m 666 /dev/urandom c 1 9
+chown root:root /dev/random /dev/urandom
+.EE
+.in
+.P
+When a Linux system starts up without much operator interaction,
+the entropy pool may be in a fairly predictable state.
+This reduces the actual amount of noise in the entropy pool
+below the estimate.
+In order to counteract this effect, it helps to carry
+entropy pool information across shut-downs and start-ups.
+To do this, add the lines to an appropriate script
+which is run during the Linux system start-up sequence:
+.P
+.in +4n
+.EX
+echo "Initializing random number generator..."
+random_seed=/var/run/random\-seed
+# Carry a random seed from start\-up to start\-up
+# Load and then save the whole entropy pool
+if [ \-f $random_seed ]; then
+    cat $random_seed >/dev/urandom
+else
+    touch $random_seed
+fi
+chmod 600 $random_seed
+poolfile=/proc/sys/kernel/random/poolsize
+[ \-r $poolfile ] && bits=$(cat $poolfile) || bits=4096
+bytes=$(expr $bits / 8)
+dd if=/dev/urandom of=$random_seed count=1 bs=$bytes
+.EE
+.in
+.P
+Also, add the following lines in an appropriate script which is
+run during the Linux system shutdown:
+.P
+.in +4n
+.EX
+# Carry a random seed from shut\-down to start\-up
+# Save the whole entropy pool
+echo "Saving random seed..."
+random_seed=/var/run/random\-seed
+touch $random_seed
+chmod 600 $random_seed
+poolfile=/proc/sys/kernel/random/poolsize
+[ \-r $poolfile ] && bits=$(cat $poolfile) || bits=4096
+bytes=$(expr $bits / 8)
+dd if=/dev/urandom of=$random_seed count=1 bs=$bytes
+.EE
+.in
+.P
+In the above examples, we assume Linux 2.6.0 or later, where
+.I /proc/sys/kernel/random/poolsize
+returns the size of the entropy pool in bits (see below).
+.\"
+.SS /proc interfaces
+The files in the directory
+.I /proc/sys/kernel/random
+(present since Linux 2.3.16) provide additional information about the
+.I /dev/random
+device:
+.TP
+.I entropy_avail
+This read-only file gives the available entropy, in bits.
+This will be a number in the range 0 to 4096.
+.TP
+.I poolsize
+This file
+gives the size of the entropy pool.
+The semantics of this file vary across kernel versions:
+.RS
+.TP
+Linux 2.4:
+This file gives the size of the entropy pool in
+.IR bytes .
+Normally, this file will have the value 512, but it is writable,
+and can be changed to any value for which an algorithm is available.
+The choices are 32, 64, 128, 256, 512, 1024, or 2048.
+.TP
+Linux 2.6 and later:
+This file is read-only, and gives the size of the entropy pool in
+.IR bits .
+It contains the value 4096.
+.RE
+.TP
+.I read_wakeup_threshold
+This file
+contains the number of bits of entropy required for waking up processes
+that sleep waiting for entropy from
+.IR /dev/random .
+The default is 64.
+.TP
+.I write_wakeup_threshold
+This file
+contains the number of bits of entropy below which we wake up
+processes that do a
+.BR select (2)
+or
+.BR poll (2)
+for write access to
+.IR /dev/random .
+These values can be changed by writing to the files.
+.TP
+.IR uuid " and " boot_id
+These read-only files
+contain random strings like 6fd5a44b\-35f4\-4ad4\-a9b9\-6b9be13e1fe9.
+The former is generated afresh for each read, the latter was
+generated once.
+.\"
+.SS ioctl(2) interface
+The following
+.BR ioctl (2)
+requests are defined on file descriptors connected to either \fI/dev/random\fP
+or \fI/dev/urandom\fP.
+All requests performed will interact with the input
+entropy pool impacting both \fI/dev/random\fP and \fI/dev/urandom\fP.
+The
+.B CAP_SYS_ADMIN
+capability is required for all requests except
+.BR RNDGETENTCNT .
+.TP
+.B RNDGETENTCNT
+Retrieve the entropy count of the input pool, the contents will be the same
+as the
+.I entropy_avail
+file under proc.
+The result will be stored in the int pointed to by the argument.
+.TP
+.B RNDADDTOENTCNT
+Increment or decrement the entropy count of the input pool
+by the value pointed to by the argument.
+.TP
+.B RNDGETPOOL
+Removed in Linux 2.6.9.
+.TP
+.B RNDADDENTROPY
+Add some additional entropy to the input pool,
+incrementing the entropy count.
+This differs from writing to \fI/dev/random\fP or \fI/dev/urandom\fP,
+which only adds some
+data but does not increment the entropy count.
+The following structure is used:
+.IP
+.in +4n
+.EX
+struct rand_pool_info {
+    int    entropy_count;
+    int    buf_size;
+    __u32  buf[0];
+};
+.EE
+.in
+.IP
+Here
+.I entropy_count
+is the value added to (or subtracted from) the entropy count, and
+.I buf
+is the buffer of size
+.I buf_size
+which gets added to the entropy pool.
+.TP
+.B RNDZAPENTCNT
+.TQ
+.B RNDCLEARPOOL
+Zero the entropy count of all pools and add some system data (such as
+wall clock) to the pools.
+.SH FILES
+.I /dev/random
+.br
+.I /dev/urandom
+.SH NOTES
+For an overview and comparison of the various interfaces that
+can be used to obtain randomness, see
+.BR random (7).
+.SH BUGS
+During early boot time, reads from
+.I /dev/urandom
+may return data prior to the entropy pool being initialized.
+.\" .SH AUTHOR
+.\" The kernel's random number generator was written by
+.\" Theodore Ts'o (tytso@athena.mit.edu).
+.SH SEE ALSO
+.BR mknod (1),
+.BR getrandom (2),
+.BR random (7)
+.P
+RFC\ 1750, "Randomness Recommendations for Security"
diff --git a/man/man4/rtc.4 b/man/man4/rtc.4
new file mode 100644
index 000000000..9619ff23c
--- /dev/null
+++ b/man/man4/rtc.4
@@ -0,0 +1,347 @@
+.\" rtc.4
+.\" Copyright 2002 Urs Thuermann (urs@isnogud.escape.de)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" $Id: rtc.4,v 1.4 2005/12/05 17:19:49 urs Exp $
+.\"
+.\" 2006-02-08 Various additions by mtk
+.\" 2006-11-26 cleanup, cover the generic rtc framework; David Brownell
+.\"
+.TH rtc 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rtc \- real-time clock
+.SH SYNOPSIS
+.nf
+#include <linux/rtc.h>
+.P
+.BI "int ioctl(" fd ", RTC_" request ", " param ");"
+.fi
+.SH DESCRIPTION
+This is the interface to drivers for real-time clocks (RTCs).
+.P
+Most computers have one or more hardware clocks which record the
+current "wall clock" time.
+These are called "Real Time Clocks" (RTCs).
+One of these usually has battery backup power so that it tracks the time
+even while the computer is turned off.
+RTCs often provide alarms and other interrupts.
+.P
+All i386 PCs, and ACPI-based systems, have an RTC that is compatible with
+the Motorola MC146818 chip on the original PC/AT.
+Today such an RTC is usually integrated into the mainboard's chipset
+(south bridge), and uses a replaceable coin-sized backup battery.
+.P
+Non-PC systems, such as embedded systems built around system-on-chip
+processors, use other implementations.
+They usually won't offer the same functionality as the RTC from a PC/AT.
+.SS RTC vs system clock
+RTCs should not be confused with the system clock, which is
+a software clock maintained by the kernel and used to implement
+.BR gettimeofday (2)
+and
+.BR time (2),
+as well as setting timestamps on files, and so on.
+The system clock reports seconds and microseconds since a start point,
+defined to be the POSIX Epoch: 1970-01-01 00:00:00 +0000 (UTC).
+(One common implementation counts timer interrupts, once
+per "jiffy", at a frequency of 100, 250, or 1000 Hz.)
+That is, it is supposed to report wall clock time, which RTCs also do.
+.P
+A key difference between an RTC and the system clock is that RTCs
+run even when the system is in a low power state (including "off"),
+and the system clock can't.
+Until it is initialized, the system clock can only report time since
+system boot ... not since the POSIX Epoch.
+So at boot time, and after resuming from a system low power state, the
+system clock will often be set to the current wall clock time using an RTC.
+Systems without an RTC need to set the system clock using another clock,
+maybe across the network or by entering that data manually.
+.SS RTC functionality
+RTCs can be read and written with
+.BR hwclock (8),
+or directly with the
+.BR ioctl (2)
+requests listed below.
+.P
+Besides tracking the date and time, many RTCs can also generate
+interrupts
+.IP \[bu] 3
+on every clock update (i.e., once per second);
+.IP \[bu]
+at periodic intervals with a frequency that can be set to
+any power-of-2 multiple in the range 2 Hz to 8192 Hz;
+.IP \[bu]
+on reaching a previously specified alarm time.
+.P
+Each of those interrupt sources can be enabled or disabled separately.
+On many systems, the alarm interrupt can be configured as a system wakeup
+event, which can resume the system from a low power state such as
+Suspend-to-RAM (STR, called S3 in ACPI systems),
+Hibernation (called S4 in ACPI systems),
+or even "off" (called S5 in ACPI systems).
+On some systems, the battery backed RTC can't issue
+interrupts, but another one can.
+.P
+The
+.I /dev/rtc
+(or
+.IR /dev/rtc0 ,
+.IR /dev/rtc1 ,
+etc.)
+device can be opened only once (until it is closed) and it is read-only.
+On
+.BR read (2)
+and
+.BR select (2)
+the calling process is blocked until the next interrupt from that RTC
+is received.
+Following the interrupt, the process can read a long integer, of which
+the least significant byte contains a bit mask encoding
+the types of interrupt that occurred,
+while the remaining 3 bytes contain the number of interrupts since the
+last
+.BR read (2).
+.SS ioctl(2) interface
+The following
+.BR ioctl (2)
+requests are defined on file descriptors connected to RTC devices:
+.TP
+.B RTC_RD_TIME
+Returns this RTC's time in the following structure:
+.IP
+.in +4n
+.EX
+struct rtc_time {
+    int tm_sec;
+    int tm_min;
+    int tm_hour;
+    int tm_mday;
+    int tm_mon;
+    int tm_year;
+    int tm_wday;     /* unused */
+    int tm_yday;     /* unused */
+    int tm_isdst;    /* unused */
+};
+.EE
+.in
+.IP
+The fields in this structure have the same meaning and ranges as for the
+.I tm
+structure described in
+.BR gmtime (3).
+A pointer to this structure should be passed as the third
+.BR ioctl (2)
+argument.
+.TP
+.B RTC_SET_TIME
+Sets this RTC's time to the time specified by the
+.I rtc_time
+structure pointed to by the third
+.BR ioctl (2)
+argument.
+To set the
+RTC's time the process must be privileged (i.e., have the
+.B CAP_SYS_TIME
+capability).
+.TP
+.B RTC_ALM_READ
+.TQ
+.B RTC_ALM_SET
+Read and set the alarm time, for RTCs that support alarms.
+The alarm interrupt must be separately enabled or disabled using the
+.BR RTC_AIE_ON ", " RTC_AIE_OFF
+requests.
+The third
+.BR ioctl (2)
+argument is a pointer to an
+.I rtc_time
+structure.
+Only the
+.IR tm_sec ,
+.IR tm_min ,
+and
+.I tm_hour
+fields of this structure are used.
+.TP
+.B RTC_IRQP_READ
+.TQ
+.B RTC_IRQP_SET
+Read and set the frequency for periodic interrupts,
+for RTCs that support periodic interrupts.
+The periodic interrupt must be separately enabled or disabled using the
+.BR RTC_PIE_ON ", " RTC_PIE_OFF
+requests.
+The third
+.BR ioctl (2)
+argument is an
+.I "unsigned long\ *"
+or an
+.IR "unsigned long" ,
+respectively.
+The value is the frequency in interrupts per second.
+The set of allowable frequencies is the multiples of two
+in the range 2 to 8192.
+Only a privileged process (i.e., one having the
+.B CAP_SYS_RESOURCE
+capability) can set frequencies above the value specified in
+.IR /proc/sys/dev/rtc/max\-user\-freq .
+(This file contains the value 64 by default.)
+.TP
+.B RTC_AIE_ON
+.TQ
+.B RTC_AIE_OFF
+Enable or disable the alarm interrupt, for RTCs that support alarms.
+The third
+.BR ioctl (2)
+argument is ignored.
+.TP
+.B RTC_UIE_ON
+.TQ
+.B RTC_UIE_OFF
+Enable or disable the interrupt on every clock update,
+for RTCs that support this once-per-second interrupt.
+The third
+.BR ioctl (2)
+argument is ignored.
+.TP
+.B RTC_PIE_ON
+.TQ
+.B RTC_PIE_OFF
+Enable or disable the periodic interrupt,
+for RTCs that support these periodic interrupts.
+The third
+.BR ioctl (2)
+argument is ignored.
+Only a privileged process (i.e., one having the
+.B CAP_SYS_RESOURCE
+capability) can enable the periodic interrupt if the frequency is
+currently set above the value specified in
+.IR /proc/sys/dev/rtc/max\-user\-freq .
+.TP
+.B RTC_EPOCH_READ
+.TQ
+.B RTC_EPOCH_SET
+Many RTCs encode the year in an 8-bit register which is either
+interpreted as an 8-bit binary number or as a BCD number.
+In both cases,
+the number is interpreted relative to this RTC's Epoch.
+The RTC's Epoch is
+initialized to 1900 on most systems but on Alpha and MIPS it might
+also be initialized to 1952, 1980, or 2000, depending on the value of
+an RTC register for the year.
+With some RTCs,
+these operations can be used to read or to set the RTC's Epoch,
+respectively.
+The third
+.BR ioctl (2)
+argument is an
+.I "unsigned long\ *"
+or an
+.IR "unsigned long" ,
+respectively, and the value returned (or assigned) is the Epoch.
+To set the RTC's Epoch the process must be privileged (i.e., have the
+.B CAP_SYS_TIME
+capability).
+.TP
+.B RTC_WKALM_RD
+.TQ
+.B RTC_WKALM_SET
+Some RTCs support a more powerful alarm interface, using these ioctls
+to read or write the RTC's alarm time (respectively) with this structure:
+.P
+.RS
+.in +4n
+.EX
+struct rtc_wkalrm {
+    unsigned char enabled;
+    unsigned char pending;
+    struct rtc_time time;
+};
+.EE
+.in
+.RE
+.IP
+The
+.I enabled
+flag is used to enable or disable the alarm interrupt,
+or to read its current status; when using these calls,
+.BR RTC_AIE_ON " and " RTC_AIE_OFF
+are not used.
+The
+.I pending
+flag is used by
+.B RTC_WKALM_RD
+to report a pending interrupt
+(so it's mostly useless on Linux, except when talking
+to the RTC managed by EFI firmware).
+The
+.I time
+field is as used with
+.B RTC_ALM_READ
+and
+.B RTC_ALM_SET
+except that the
+.IR tm_mday ,
+.IR tm_mon ,
+and
+.I tm_year
+fields are also valid.
+A pointer to this structure should be passed as the third
+.BR ioctl (2)
+argument.
+.SH FILES
+.TP
+.I /dev/rtc
+.TQ
+.I /dev/rtc0
+.TQ
+.I /dev/rtc1
+.TQ
+\&.\|.\|.
+RTC special character device files.
+.TP
+.I /proc/driver/rtc
+status of the (first) RTC.
+.SH NOTES
+When the kernel's system time is synchronized with an external
+reference using
+.BR adjtimex (2)
+it will update a designated RTC periodically every 11 minutes.
+To do so, the kernel has to briefly turn off periodic interrupts;
+this might affect programs using that RTC.
+.P
+An RTC's Epoch has nothing to do with the POSIX Epoch which is
+used only for the system clock.
+.P
+If the year according to the RTC's Epoch and the year register is
+less than 1970 it is assumed to be 100 years later, that is, between 2000
+and 2069.
+.P
+Some RTCs support "wildcard" values in alarm fields, to support
+scenarios like periodic alarms at fifteen minutes after every hour,
+or on the first day of each month.
+Such usage is nonportable;
+portable user-space code expects only a single alarm interrupt, and
+will either disable or reinitialize the alarm after receiving it.
+.P
+Some RTCs support periodic interrupts with periods that are multiples
+of a second rather than fractions of a second;
+multiple alarms;
+programmable output clock signals;
+nonvolatile memory;
+and other hardware
+capabilities that are not currently exposed by this API.
+.SH SEE ALSO
+.BR date (1),
+.BR adjtimex (2),
+.BR gettimeofday (2),
+.BR settimeofday (2),
+.BR stime (2),
+.BR time (2),
+.BR gmtime (3),
+.BR time (7),
+.BR hwclock (8)
+.P
+.I Documentation/rtc.txt
+in the Linux kernel source tree
diff --git a/man/man4/sd.4 b/man/man4/sd.4
new file mode 100644
index 000000000..5a3221146
--- /dev/null
+++ b/man/man4/sd.4
@@ -0,0 +1,117 @@
+.\" sd.4
+.\" Copyright 1992 Rickard E. Faith (faith@cs.unc.edu)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sd 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sd \- driver for SCSI disk drives
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/hdreg.h>        " "/* for HDIO_GETGEO */"
+.BR "#include <linux/fs.h>           " "/* for BLKGETSIZE and BLKRRPART */"
+.fi
+.SH CONFIGURATION
+The block device name has the following form:
+.BI sd lp,
+where
+.I l
+is a letter denoting the physical drive, and
+.I p
+is a number denoting the partition on that physical drive.
+Often, the partition number,
+.IR p ,
+will be left off when the device corresponds to the whole drive.
+.P
+SCSI disks have a major device number of 8, and a minor device number of
+the form (16 *
+.IR drive_number ") + " partition_number ,
+where
+.I drive_number
+is the number of the physical drive in order of detection, and
+.I partition_number
+is as follows:
+.IP \[bu] 3
+partition 0 is the whole drive
+.IP \[bu]
+partitions 1\[en]4 are the DOS "primary" partitions
+.IP \[bu]
+partitions 5\[en]8 are the DOS "extended" (or "logical") partitions
+.P
+For example,
+.I /dev/sda
+will have major 8, minor 0, and will refer to all of the first SCSI drive
+in the system; and
+.I /dev/sdb3
+will have major 8, minor 19, and will refer to the third DOS "primary"
+partition on the second SCSI drive in the system.
+.P
+At this time, only block devices are provided.
+Raw devices have not yet been implemented.
+.SH DESCRIPTION
+The following
+.IR ioctl s
+are provided:
+.TP
+.B HDIO_GETGEO
+Returns the BIOS disk parameters in the following structure:
+.P
+.in +4n
+.EX
+struct hd_geometry {
+    unsigned char  heads;
+    unsigned char  sectors;
+    unsigned short cylinders;
+    unsigned long  start;
+};
+.EE
+.in
+.IP
+A pointer to this structure is passed as the
+.BR ioctl (2)
+parameter.
+.IP
+The information returned in the parameter is the disk geometry of the drive
+.I "as understood by DOS!"
+This geometry is
+.I not
+the physical geometry of the drive.
+It is used when constructing the
+drive's partition table, however, and is needed for convenient operation
+of
+.BR fdisk (1),
+.BR efdisk (1),
+and
+.BR lilo (1).
+If the geometry information is not available, zero will be returned for all
+of the parameters.
+.TP
+.B BLKGETSIZE
+Returns the device size in sectors.
+The
+.BR ioctl (2)
+parameter should be a pointer to a
+.IR long .
+.TP
+.B BLKRRPART
+Forces a reread of the SCSI disk partition tables.
+No parameter is needed.
+.IP
+The SCSI
+.BR ioctl (2)
+operations are also supported.
+If the
+.BR ioctl (2)
+parameter is required, and it is NULL, then
+.BR ioctl (2)
+fails with the error
+.BR EINVAL .
+.SH FILES
+.TP
+.I /dev/sd[a\-h]
+the whole device
+.TP
+.I /dev/sd[a\-h][0\-8]
+individual block partitions
+.\".SH SEE ALSO
+.\".BR scsi (4)
diff --git a/man/man4/sk98lin.4 b/man/man4/sk98lin.4
new file mode 100644
index 000000000..3bbbd69f0
--- /dev/null
+++ b/man/man4/sk98lin.4
@@ -0,0 +1,580 @@
+'\" t
+.\" (C)Copyright 1999-2003 Marvell(R) -- linux@syskonnect.de
+.\" sk98lin.4 1.1 2003/12/17 10:03:18
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" This manpage can be viewed using `groff -Tascii -man sk98lin.4 | less`
+.\"
+.TH sk98lin 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sk98lin \- Marvell/SysKonnect Gigabit Ethernet driver v6.21
+.SH SYNOPSIS
+.B insmod sk98lin.o
+.RB [ Speed_A=\c
+.IR i,j,... ]
+.RB [ Speed_B=\c
+.IR i,j,... ]
+.RB [ AutoNeg_A=\c
+.IR i,j,... ]
+.RB [ AutoNeg_B=\c
+.IR i,j,... ]
+.RB [ DupCap_A=\c
+.IR i,j,... ]
+.RB [ DupCap_B=\c
+.IR i,j,... ]
+.RB [ FlowCtrl_A=\c
+.IR i,j,... ]
+.RB [ FlowCtrl_B=\c
+.IR i,j,... ]
+.RB [ Role_A=\c
+.IR i,j,... ]
+.RB [ Role_B=\c
+.IR i,j,... ]
+.RB [ ConType=\c
+.IR i,j,... ]
+.RB [ Moderation=\c
+.IR i,j,... ]
+.RB [ IntsPerSec=\c
+.IR i,j,... ]
+.RB [ PrefPort=\c
+.IR i,j,... ]
+.RB [ RlmtMode=\c
+.IR i,j,... ]
+.SH DESCRIPTION
+.ad l
+.hy 0
+.BR Note :
+This obsolete driver was removed in Linux 2.6.26.
+.P
+.B sk98lin
+is the Gigabit Ethernet driver for
+Marvell and SysKonnect network adapter cards.
+It supports SysKonnect SK-98xx/SK-95xx
+compliant Gigabit Ethernet Adapter and
+any Yukon compliant chipset.
+.P
+When loading the driver using insmod,
+parameters for the network adapter cards
+might be stated as a sequence of comma separated commands.
+If for instance two network adapters are installed and AutoNegotiation on
+Port A of the first adapter should be ON,
+but on the Port A of the second adapter switched OFF, one must enter:
+.P
+.in +4n
+.EX
+insmod sk98lin.o AutoNeg_A=On,Off
+.EE
+.in
+.P
+After
+.B sk98lin
+is bound to one or more adapter cards and the
+.I /proc
+filesystem is mounted on your system, a dedicated statistics file
+will be created in the folder
+.I /proc/net/sk98lin
+for all ports of the installed network adapter cards.
+Those files are named
+.IR eth[x] ,
+where
+.I x
+is the number of the interface that has been assigned to a
+dedicated port by the system.
+.P
+If loading is finished, any desired IP address can be
+assigned to the respective
+.I eth[x]
+interface using the
+.BR ifconfig (8)
+command.
+This causes the adapter to connect to the Ethernet and to display a status
+message on the console saying "ethx: network connection up using port y"
+followed by the configured or detected connection parameters.
+.P
+The
+.B sk98lin
+also supports large frames (also called jumbo frames).
+Using jumbo frames can improve throughput tremendously when
+transferring large amounts of data.
+To enable large frames, the MTU (maximum transfer unit) size
+for an interface is to be set to a high value.
+The default MTU size is 1500 and can be changed up to 9000 (bytes).
+Setting the MTU size can be done when assigning the IP address
+to the interface or later by using the
+.BR ifconfig (8)
+command with the mtu parameter.
+If for instance eth0 needs an IP
+address and a large frame MTU size,
+the following two commands might be used:
+.P
+.in +4n
+.EX
+ifconfig eth0 10.1.1.1
+ifconfig eth0 mtu 9000
+.EE
+.in
+.P
+Those two commands might even be combined into one:
+.P
+.in +4n
+.EX
+ifconfig eth0 10.1.1.1 mtu 9000
+.EE
+.in
+.P
+Note that large frames can be used only if permitted by
+your network infrastructure.
+This means, that any switch being used in your Ethernet must
+also support large frames.
+Quite some switches support large frames,
+but need to be configured to do so.
+Most of the times, their default setting is to support only
+standard frames with an MTU size of 1500 (bytes).
+In addition to the switches inside the network,
+all network adapters that are to be used must also be
+enabled regarding jumbo frames.
+If an adapter is not set to receive large frames, it will simply drop them.
+.P
+Switching back to the standard Ethernet frame size can be done by using the
+.BR ifconfig (8)
+command again:
+.P
+.in +4n
+.EX
+ifconfig eth0 mtu 1500
+.EE
+.in
+.P
+The Marvell/SysKonnect Gigabit Ethernet driver for Linux is able to
+support VLAN and Link Aggregation according to
+IEEE standards 802.1, 802.1q, and 802.3ad.
+Those features are available only after installation of open source modules
+which can be found on the Internet:
+.P
+.IR VLAN :
+.UR http://www.candelatech.com\:/\[ti]greear\:/vlan.html
+.UE
+.br
+.I Link
+.IR Aggregation :
+.UR http://www.st.rim.or.jp\:/\[ti]yumo
+.UE
+.P
+Note that Marvell/SysKonnect does not offer any support for these
+open source modules and does not take the responsibility for any
+kind of failures or problems arising when using these modules.
+.SS Parameters
+.TP
+.BI Speed_A= i,j,...
+This parameter is used to set the speed capabilities of port A of an
+adapter card.
+It is valid only for Yukon copper adapters.
+Possible values are:
+.IR 10 ,
+.IR 100 ,
+.IR 1000 ,
+or
+.IR Auto ;
+.I Auto
+is the default.
+Usually, the speed is negotiated between the two ports
+during link establishment.
+If this fails,
+a port can be forced to a specific setting with this parameter.
+.TP
+.BI Speed_B= i,j,...
+This parameter is used to set the speed capabilities of port B of
+an adapter card.
+It is valid only for Yukon copper adapters.
+Possible values are:
+.IR 10 ,
+.IR 100 ,
+.IR 1000 ,
+or
+.IR Auto ;
+.I Auto
+is the default.
+Usually, the speed is negotiated between the two ports during link
+establishment.
+If this fails,
+a port can be forced to a specific setting with this parameter.
+.TP
+.BI AutoNeg_A= i,j,...
+Enables or disables the use of autonegotiation of port A of an adapter card.
+Possible values are:
+.IR On ,
+.IR Off ,
+or
+.IR Sense ;
+.I On
+is the default.
+The
+.I Sense
+mode automatically detects whether the link partner supports
+auto-negotiation or not.
+.TP
+.BI AutoNeg_B= i,j,...
+Enables or disables the use of autonegotiation of port B of an adapter card.
+Possible values are:
+.IR On ,
+.IR Off ,
+or
+.IR Sense ;
+.I On
+is the default.
+The
+.I Sense
+mode automatically detects whether the link partner supports
+auto-negotiation or not.
+.TP
+.BI DupCap_A= i,j,...
+This parameter indicates the duplex mode to be used for port A
+of an adapter card.
+Possible values are:
+.IR Half ,
+.IR Full ,
+or
+.IR Both ;
+.I Both
+is the default.
+This parameter is relevant only if AutoNeg_A of port A is not set to
+.IR Sense .
+If AutoNeg_A is set to
+.IR On ,
+all three values of DupCap_A (
+.IR Half ,
+.IR Full ,
+or
+.IR Both )
+might be stated.
+If AutoNeg_A is set to
+.IR Off ,
+only DupCap_A values
+.I Full
+and
+.I Half
+are allowed.
+This DupCap_A parameter is useful if your link partner does not
+support all possible duplex combinations.
+.TP
+.BI DupCap_B= i,j,...
+This parameter indicates the duplex mode to be used for port B
+of an adapter card.
+Possible values are:
+.IR Half ,
+.IR Full ,
+or
+.IR Both ;
+.I Both
+is the default.
+This parameter is relevant only if AutoNeg_B of port B is not set to
+.IR Sense .
+If AutoNeg_B is set to
+.IR On ,
+all three values of DupCap_B (
+.IR Half ,
+.IR Full ,
+or
+.IR Both )
+might be stated.
+If AutoNeg_B is set to
+.IR Off ,
+only DupCap_B values
+.I Full
+and
+.I Half
+are allowed.
+This DupCap_B parameter is useful if your link partner does not
+support all possible duplex combinations.
+.TP
+.BI FlowCtrl_A= i,j,...
+This parameter can be used to set the flow control capabilities the
+port reports during auto-negotiation.
+Possible values are:
+.IR Sym ,
+.IR SymOrRem ,
+.IR LocSend ,
+or
+.IR None ;
+.I SymOrRem
+is the default.
+The different modes have the following meaning:
+.RS
+.TP
+.IR Sym " = Symmetric"
+Both link partners are allowed to send PAUSE frames.
+.TP
+.IR SymOrRem " = SymmetricOrRemote"
+Both or only remote partner are allowed to send PAUSE frames.
+.TP
+.IR LocSend " = LocalSend"
+Only local link partner is allowed to send PAUSE frames.
+.TP
+.IR None " = None"
+No link partner is allowed to send PAUSE frames.
+.RE
+.IP
+Note that this parameter is ignored if AutoNeg_A is set to
+.IR Off .
+.TP
+.BI FlowCtrl_B= i,j,...
+This parameter can be used to set the flow control capabilities the
+port reports during auto-negotiation.
+Possible values are:
+.IR Sym ,
+.IR SymOrRem ,
+.IR LocSend ,
+or
+.IR None ;
+.I SymOrRem
+is the default.
+The different modes have the following meaning:
+.RS
+.TP
+.IR Sym " = Symmetric"
+Both link partners are allowed to send PAUSE frames.
+.TP
+.IR SymOrRem " = SymmetricOrRemote"
+Both or only remote partner are allowed to send PAUSE frames.
+.TP
+.IR LocSend " = LocalSend"
+Only local link partner is allowed to send PAUSE frames.
+.TP
+.IR None " = None"
+No link partner is allowed to send PAUSE frames.
+.RE
+.IP
+Note that this parameter is ignored if AutoNeg_B is set to
+.IR Off .
+.TP
+.BI Role_A= i,j,...
+This parameter is valid only for 1000Base-T adapter cards.
+For two 1000Base-T ports to communicate,
+one must take the role of the master (providing timing information),
+while the other must be the slave.
+Possible values are:
+.IR Auto ,
+.IR Master ,
+or
+.IR Slave ;
+.I Auto
+is the default.
+Usually, the role of a port is negotiated between two ports during
+link establishment, but if that fails the port A of an adapter card
+can be forced to a specific setting with this parameter.
+.TP
+.BI Role_B= i,j,...
+This parameter is valid only for 1000Base-T adapter cards.
+For two 1000Base-T ports to communicate, one must take
+the role of the master (providing timing information),
+while the other must be the slave.
+Possible values are:
+.IR Auto ,
+.IR Master ,
+or
+.IR Slave ;
+.I Auto
+is the default.
+Usually, the role of a port is negotiated between
+two ports during link establishment, but if that fails
+the port B of an adapter card can be forced to a
+specific setting with this parameter.
+.TP
+.BI ConType= i,j,...
+This parameter is a combination of all five per-port parameters
+within one single parameter.
+This simplifies the configuration of both ports of an adapter card.
+The different values of this variable reflect the
+most meaningful combinations of port parameters.
+Possible values and their corresponding combination of per-port parameters:
+.IP
+.TS
+lb lb lb lb lb lb
+l l l l l l.
+ConType	DupCap	AutoNeg	FlowCtrl	Role	Speed
+\fIAuto\fP	Both	On	SymOrRem	Auto	Auto
+\fI100FD\fP	Full	Off	None	Auto	100
+\fI100HD\fP	Half	Off	None	Auto	100
+\fI10FD\fP	Full	Off	None	Auto	10
+\fI10HD\fP	Half	Off	None	Auto	10
+.TE
+.IP
+Stating any other port parameter together with this
+.I ConType
+parameter will result in a merged configuration of those settings.
+This is due to
+the fact, that the per-port parameters (e.g.,
+.IR Speed_A )
+have a higher priority than the combined variable
+.IR ConType .
+.TP
+.BI Moderation= i,j,...
+Interrupt moderation is employed to limit the maximum number of interrupts
+the driver has to serve.
+That is, one or more interrupts (which indicate any transmit or
+receive packet to be processed) are queued until the driver processes them.
+When queued interrupts are to be served, is determined by the
+.I IntsPerSec
+parameter, which is explained later below.
+Possible moderation modes are:
+.IR None ,
+.IR Static ,
+or
+.IR Dynamic ;
+.I None
+is the default.
+The different modes have the following meaning:
+.IP
+.I None
+No interrupt moderation is applied on the adapter card.
+Therefore, each transmit or receive interrupt is served immediately
+as soon as it appears on the interrupt line of the adapter card.
+.IP
+.I Static
+Interrupt moderation is applied on the adapter card.
+All transmit and receive interrupts are queued until
+a complete moderation interval ends.
+If such a moderation interval ends, all queued interrupts
+are processed in one big bunch without any delay.
+The term
+.I Static
+reflects the fact, that interrupt moderation is always enabled,
+regardless how much network load is currently passing via a
+particular interface.
+In addition, the duration of the moderation interval has a fixed
+length that never changes while the driver is operational.
+.IP
+.I Dynamic
+Interrupt moderation might be applied on the adapter card,
+depending on the load of the system.
+If the driver detects that the system load is too high,
+the driver tries to shield the system against too much network
+load by enabling interrupt moderation.
+If\[em]at a later time\[em]the CPU utilization decreases
+again (or if the network load is negligible), the interrupt
+moderation will automatically be disabled.
+.IP
+Interrupt moderation should be used when the driver has to
+handle one or more interfaces with a high network load,
+which\[em]as a consequence\[em]leads also to a high CPU utilization.
+When moderation is applied in such high network load situations,
+CPU load might be reduced by 20\[en]30% on slow computers.
+.IP
+Note that the drawback of using interrupt moderation is an increase of
+the round-trip-time (RTT), due to the queuing and serving of
+interrupts at dedicated moderation times.
+.TP
+.BI IntsPerSec= i,j,...
+This parameter determines the length of any interrupt moderation interval.
+Assuming that static interrupt moderation is to be used, an
+.I IntsPerSec
+parameter value of 2000 will lead to an interrupt moderation interval of
+500 microseconds.
+Possible values for this parameter are in the range of
+30...40000 (interrupts per second).
+The default value is 2000.
+.IP
+This parameter is used only if either static or dynamic interrupt moderation
+is enabled on a network adapter card.
+This parameter is ignored if no moderation is applied.
+.IP
+Note that the duration of the moderation interval is to be chosen with care.
+At first glance, selecting a very long duration (e.g., only 100 interrupts per
+second) seems to be meaningful, but the increase of packet-processing delay
+is tremendous.
+On the other hand, selecting a very short moderation time might
+compensate the use of any moderation being applied.
+.TP
+.BI PrefPort= i,j,...
+This parameter is used to force the preferred port to
+A or B (on dual-port network adapters).
+The preferred port is the one that is used if both ports A and B are
+detected as fully functional.
+Possible values are:
+.I A
+or
+.IR B ;
+.I A
+is the default.
+.TP
+.BI RlmtMode= i,j,...
+RLMT monitors the status of the port.
+If the link of the active port fails,
+RLMT switches immediately to the standby link.
+The virtual link is maintained as long as at least one "physical" link is up.
+This parameters states how RLMT should monitor both ports.
+Possible values are:
+.IR CheckLinkState ,
+.IR CheckLocalPort ,
+.IR CheckSeg ,
+or
+.IR DualNet ;
+.I CheckLinkState
+is the default.
+The different modes have the following meaning:
+.IP
+.I CheckLinkState
+Check link state only: RLMT uses the link state reported by the adapter
+hardware for each individual port to determine whether a port can be used
+for all network traffic or not.
+.IP
+.I CheckLocalPort
+In this mode, RLMT monitors the network path between the two
+ports of an adapter by regularly exchanging packets between them.
+This mode requires a network configuration in which the
+two ports are able to "see" each other (i.e., there
+must not be any router between the ports).
+.IP
+.I CheckSeg
+Check local port and segmentation:
+This mode supports the same functions as the CheckLocalPort
+mode and additionally checks network segmentation between the ports.
+Therefore, this mode is to be used only if Gigabit Ethernet
+switches are installed on the network that have been
+configured to use the Spanning Tree protocol.
+.IP
+.I DualNet
+In this mode, ports A and B are used as separate devices.
+If you have a dual port adapter, port A will be configured as
+.I eth[x]
+and port B as
+.IR eth[x+1] .
+Both ports can be used independently with distinct IP addresses.
+The preferred port setting is not used.
+RLMT is turned off.
+.IP
+Note that RLMT modes
+.I CheckLocalPort
+and
+.I CheckLinkState
+are designed to operate in configurations where a
+network path between the ports on one adapter exists.
+Moreover, they are not designed to work where adapters are
+connected back-to-back.
+.SH FILES
+.TP
+.I /proc/net/sk98lin/eth[x]
+The statistics file of a particular interface of an adapter card.
+It contains generic information about the adapter card plus a detailed
+summary of all transmit and receive counters.
+.TP
+.I /usr/src/linux/Documentation/networking/sk98lin.txt
+This is the
+.I README
+file of the
+.I sk98lin
+driver.
+It contains a detailed installation HOWTO and describes all parameters
+of the driver.
+It denotes also common problems and provides the solution to them.
+.SH BUGS
+Report any bugs to linux@syskonnect.de
+.\" .SH AUTHORS
+.\" Ralph Roesler \[em] rroesler@syskonnect.de
+.\" .br
+.\" Mirko Lindner \[em] mlindner@syskonnect.de
+.SH SEE ALSO
+.BR ifconfig (8),
+.BR insmod (8),
+.BR modprobe (8)
diff --git a/man/man4/smartpqi.4 b/man/man4/smartpqi.4
new file mode 100644
index 000000000..0da664131
--- /dev/null
+++ b/man/man4/smartpqi.4
@@ -0,0 +1,496 @@
+'\" t
+.\" Copyright (C) 2019-2023, Microchip Technology Inc. and its subsidiaries
+.\" Copyright (C) 2016-2018, Microsemi Corporation
+.\" Copyright (C) 2016, PMC-Sierra, Inc.
+.\" Written by Kevin Barnett <kevin.barnett@microchip.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.TH smartpqi 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+smartpqi \- Microchip Smart Storage SCSI driver
+.SH SYNOPSIS
+.SY "modprobe smartpqi"
+.RB [ disable_device_id_wildcards= { 0 | 1 }]
+.RB [ disable_heartbeat= { 0 | 1 }]
+.RB [ disable_ctrl_shutdown= { 0 | 1 }]
+.RB [ lockup_action= { none | reboot | panic }]
+.RB [ expose_ld_first= { 0 | 1 }]
+.RB [ hide_vsep= { 0 | 1 }]
+.RB [ disable_managed_interrupts= { 0 | 1 }]
+.RB [ ctrl_ready_timeout= { 0 |[ 30 , 1800 ]}]
+.YS
+.SH DESCRIPTION
+.B smartpqi
+is a SCSI driver for Microchip Smart Storage controllers.
+.SS Supported \f[BI]ioctl\fP\/() operations
+For compatibility with applications written for the
+.BR cciss (4)
+and
+.BR hpsa (4)
+drivers, many, but not all of the
+.BR ioctl (2)
+operations supported by the
+.B hpsa
+driver are also supported by the
+.B smartpqi
+driver.
+The data structures used by these operations
+are described in the Linux kernel source file
+.IR include/linux/cciss_ioctl.h .
+.TP
+.B CCISS_DEREGDISK
+.TQ
+.B CCISS_REGNEWDISK
+.TQ
+.B CCISS_REGNEWD
+These operations
+all do exactly the same thing, which is to cause the driver to re-scan
+for new devices.
+This does exactly the same thing as writing to the
+.BR smartpqi -specific
+host
+.I rescan
+attribute.
+.TP
+.B CCISS_GETPCIINFO
+This operation returns the PCI domain, bus,
+device, and function and "board ID" (PCI subsystem ID).
+.TP
+.B CCISS_GETDRIVVER
+This operation returns the driver version in four bytes, encoded as:
+.IP
+.in +4n
+.EX
+(major_version << 28) | (minor_version << 24) |
+        (release << 16) | revision
+.EE
+.in
+.TP
+.B CCISS_PASSTHRU
+Allows BMIC and CISS commands to be passed through to the controller.
+.SS Boot options
+.TP
+.BR disable_device_id_wildcards= { 0 | 1 }
+Disables support for device ID wildcards.
+The default value is 0 (wildcards are enabled).
+.TP
+.BR disable_heartbeat= { 0 | 1 }
+Disables support for the controller's heartbeat check.
+This parameter is used for debugging purposes.
+The default value is 0 (the controller's heartbeat check is enabled).
+.TP
+.BR disable_ctrl_shutdown= { 0 | 1 }
+Disables support for shutting down the controller in the
+event of a controller lockup.
+The default value is 0 (controller will be shut down).
+.TP
+.BR lockup_action= { none | reboot | panic }
+Specifies the action the driver takes when a controller
+lockup is detected.
+The default action is
+.BR none .
+.TS
+l l
+---
+l l.
+parameter	action
+\fBnone\fP	take controller offline only
+\fBreboot\fP	reboot the system
+\fBpanic\fP	panic the system
+.TE
+.TP
+.BR expose_ld_first= { 0 | 1 }
+This option exposes logical devices to the OS before physical devices.
+The default value is 0 (physical devices exposed first).
+.TP
+.BR hide_vsep= { 0 | 1 }
+This option disables exposure of the virtual SEP to the OS.
+The default value is 0 (virtual SEP is exposed).
+.TP
+.BR disable_managed_interrupts= { 0 | 1 }
+Disables driver utilization of Linux kernel managed interrupts for controllers.
+The managed interrupts feature automatically distributes interrupts
+to all available CPUs and assigns SMP affinity.
+The default value is 0 (managed interrupts enabled).
+.TP
+.BR ctrl_ready_timeout= { 0 |[ 30 , 1800 ]}
+This option specifies the timeout in seconds for the driver to wait
+for the controller to be ready.
+The valid range is 0 or
+.RB [ 30 ", " 1800 ].
+The default value is 0,
+which causes the driver to use a timeout of 180 seconds.
+.SH FILES
+.SS Device nodes
+Disk drives are accessed via the SCSI disk driver
+.RI ( sd ),
+tape drives via the SCSI tape driver
+.RI ( st ),
+and the RAID controller via the SCSI generic driver
+.RI ( sg ),
+with device nodes named
+.IR /dev/sd *,
+.IR /dev/st *,
+and
+.IR /dev/sg *,
+respectively.
+.SS SmartPQI-specific host attribute files in \f[BI]/sys\fP
+.TP
+.IR /sys/class/scsi_host/host * /rescan
+The host
+.I rescan
+attribute is a write-only attribute.
+Writing to this attribute will cause the driver to scan for new,
+changed, or removed devices (e.g., hot-plugged tape drives, or newly
+configured or deleted logical volumes) and notify the SCSI mid-layer of
+any changes detected.
+Usually this action is triggered automatically by configuration
+changes, so the user should not normally have to write to this file.
+Doing so may be useful when hot-plugging devices such as tape drives or
+entire storage boxes containing pre-configured logical volumes.
+.TP
+.IR /sys/class/scsi_host/host * /lockup_action
+The host
+.I lockup_action
+attribute is a read/write attribute.
+This attribute will cause the driver to perform a specific action in the
+unlikely event that a controller lockup has been detected.
+See
+.B OPTIONS
+above
+for an explanation of the
+.I lockup_action
+values.
+.TP
+.IR /sys/class/scsi_host/host * /driver_version
+The
+.I driver_version
+attribute is read-only.
+This attribute contains the smartpqi driver version.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_host/host1/driver_version
+1.1.2\-126
+.EE
+.in
+.TP
+.IR /sys/class/scsi_host/host * /firmware_version
+The
+.I firmware_version
+attribute is read-only.
+This attribute contains the controller firmware version.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_host/host1/firmware_version
+1.29\-112
+.EE
+.in
+.TP
+.IR /sys/class/scsi_host/host * /model
+The
+.I model
+attribute is read-only.
+This attribute contains the product identification string of the controller.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_host/host1/model
+1100\-16i
+.EE
+.in
+.TP
+.IR /sys/class/scsi_host/host * /serial_number
+The
+.I serial_number
+attribute is read-only.
+This attribute contains the unique identification number of the controller.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_host/host1/serial_number
+6A316373777
+.EE
+.in
+.TP
+.IR /sys/class/scsi_host/host * /vendor
+The
+.I vendor
+attribute is read-only.
+This attribute contains the vendor identification string of the controller.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_host/host1/vendor
+Adaptec
+.EE
+.in
+.TP
+.IR /sys/class/scsi_host/host * /enable_stream_detection
+The
+.I enable_stream_detection
+attribute is read-write.
+This attribute enables/disables stream detection in the driver.
+Enabling stream detection can improve sequential write performance
+for ioaccel-enabled volumes.
+See the
+.B ssd_smart_path_enabled
+disk attribute section for details on ioaccel-enabled volumes.
+The default value is 1 (stream detection enabled).
+.IP
+Enable example:
+.IP
+.in +4n
+.EX
+$ \c
+.B echo 1 > /sys/class/scsi_host/host1/enable_stream_detection
+.EE
+.in
+.TP
+.IR /sys/class/scsi_host/host * /enable_r5_writes
+The
+.I enable_r5_writes
+attribute is read-write.
+This attribute enables/disables RAID 5 write operations
+for ioaccel-enabled volumes.
+Enabling can improve sequential write performance.
+See the
+.B ssd_smart_path_enabled
+disk attribute section for details on ioaccel-enabled volumes.
+The default value is 1 (RAID 5 writes enabled).
+.IP
+Enable example:
+.IP
+.in +4n
+.EX
+$ \c
+.B echo 1 > /sys/class/scsi_host/host1/enable_r5_writes
+.EE
+.in
+.TP
+.IR /sys/class/scsi_host/host * /enable_r6_writes
+The
+.I enable_r6_writes
+attribute is read-write.
+This attribute enables/disables RAID 6 write operations
+for ioaccel-enabled volumes.
+Enabling can improve sequential write performance.
+See the
+.B ssd_smart_path_enabled
+disk attribute section for details on ioaccel-enabled volumes.
+The default value is 1 (RAID 6 writes enabled).
+.IP
+Enable example:
+.IP
+.in +4n
+.EX
+$ \c
+.B echo 1 > /sys/class/scsi_host/host1/enable_r6_writes
+.EE
+.in
+.SS SmartPQI-specific disk attribute files in \f[BI]/sys\fP
+In the file specifications below,
+.I c
+stands for the number of the appropriate SCSI controller,
+.I b
+is the bus number,
+.I t
+the target number, and
+.I l
+is the logical unit number (LUN).
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/raid_level
+The
+.I raid_level
+attribute is read-only.
+This attribute contains the RAID level of the logical volume.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_disk/4:0:0:0/device/raid_level
+RAID 0
+.EE
+.in
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/sas_address
+The
+.I sas_address
+attribute is read-only.
+This attribute contains the SAS address of the device.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_disk/1:0:3:0/device/sas_address
+0x5001173d028543a2
+.EE
+.in
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/ssd_smart_path_enabled
+The
+.I ssd_smart_path_enabled
+attribute is read-only.
+This attribute is for ioaccel-enabled volumes.
+(Ioaccel is an alternative driver submission path that allows the
+driver to send I/O requests directly to backend SCSI devices,
+bypassing the controller firmware.
+This results in an increase in performance.
+This method is used for HBA disks and for logical volumes comprised of SSDs.)
+Contains 1 if ioaccel is enabled for the volume and 0 otherwise.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_disk/1:0:3:0/device/ssd_smart_path_enabled
+0
+.EE
+.in
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/lunid
+The
+.I lunid
+attribute is read-only.
+This attribute contains the SCSI LUN ID for the device.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_disk/13:1:0:3/device/lunid
+0x0300004000000000
+.EE
+.in
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/unique_id
+The
+.I unique_id
+attribute is read-only.
+This attribute contains a 16-byte ID
+that uniquely identifies the device within the controller.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_disk/13:1:0:3/device/unique_id
+600508B1001C6D4723A8E98D704FDB94
+.EE
+.in
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/path_info
+The
+.I path_info
+attribute is read-only.
+This attribute contains the
+.IR c : b : t : l
+of the device
+along with the device type
+and whether the device is Active or Inactive.
+If the device is an HBA device,
+.I path_info
+will also display the PORT, BOX, and BAY the device is plugged into.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_disk/13:1:0:3/device/path_info
+[13:1:0:3]    Direct-Access     Active
+\&
+$ \c
+.B cat /sys/class/scsi_disk/12:0:9:0/device/path_info
+[12:0:9:0]  Direct-Access   PORT: C1 BOX: 1 BAY: 14 Inactive
+[12:0:9:0]  Direct-Access   PORT: C0 BOX: 1 BAY: 14 Active
+.EE
+.in
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/raid_bypass_cnt
+The
+.I raid_bypass_cnt
+attribute is read-only.
+This attribute contains the number of I/O requests
+that have gone through the ioaccel path
+for ioaccel-enabled volumes.
+See the
+.B ssd_smart_path_enabled
+disk attribute section for details on ioaccel-enabled volumes.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B cat /sys/class/scsi_disk/13:1:0:3/device/raid_bypass_cnt
+0x300
+.EE
+.in
+.TP
+.IR /sys/class/scsi_disk/ c : b : t : l /device/sas_ncq_prio_enable
+The
+.I sas_ncq_prio_enable
+attribute is read/write.
+This attribute enables SATA NCQ priority support.
+This attribute works only when device has NCQ support
+and controller firmware can handle IO with NCQ priority attribute.
+.IP
+For example:
+.IP
+.in +4n
+.EX
+$ \c
+.B echo 1 > /sys/class/scsi_disk/13:1:0:3/device/sas_ncq_prio_enable
+.EE
+.in
+.SH VERSIONS
+The
+.B smartpqi
+driver was added in Linux 4.9.
+.SH NOTES
+.SS Configuration
+To configure a Microchip Smart Storage controller,
+refer to the User Guide for the controller,
+which can be found by searching for the specific controller at
+.UR https://www.microchip.com/design-centers/storage
+.UE .
+.SH HISTORY
+.I /sys/class/scsi_host/host*/version
+was replaced by two sysfs entries:
+.IP
+.I /sys/class/scsi_host/host*/driver_version
+.IP
+.I /sys/class/scsi_host/host*/firmware_version
+.SH SEE ALSO
+.BR cciss (4),
+.BR hpsa (4),
+.BR sd (4),
+.BR st (4),
+.BR sg (4)
+.P
+.I Documentation/ABI/testing/sysfs\-bus\-pci\-devices\-cciss
+in the Linux kernel source tree.
diff --git a/man/man4/st.4 b/man/man4/st.4
new file mode 100644
index 000000000..3dd16d744
--- /dev/null
+++ b/man/man4/st.4
@@ -0,0 +1,950 @@
+.\" Copyright 1995 Robert K. Nichols (Robert.K.Nichols@att.com)
+.\" Copyright 1999-2005 Kai Mäkisara (Kai.Makisara@kolumbus.fi)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH st 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+st \- SCSI tape device
+.SH SYNOPSIS
+.nf
+.B #include <sys/mtio.h>
+.P
+.BI "int ioctl(int " fd ", int " request " [, (void *)" arg3 "]);"
+.BI "int ioctl(int " fd ", MTIOCTOP, (struct mtop *)" mt_cmd );
+.BI "int ioctl(int " fd ", MTIOCGET, (struct mtget *)" mt_status );
+.BI "int ioctl(int " fd ", MTIOCPOS, (struct mtpos *)" mt_pos );
+.fi
+.SH DESCRIPTION
+The
+.B st
+driver provides the interface to a variety of SCSI tape devices.
+Currently, the driver takes control of all detected devices of type
+\[lq]sequential-access\[rq].
+The
+.B st
+driver uses major device number 9.
+.P
+Each device uses eight minor device numbers.
+The lowermost five bits
+in the minor numbers are assigned sequentially in the order of
+detection.
+In the 2.6 kernel, the bits above the eight lowermost bits are
+concatenated to the five lowermost bits to form the tape number.
+The minor numbers can be grouped into
+two sets of four numbers: the principal (auto-rewind) minor device numbers,
+.IR n ,
+and the \[lq]no-rewind\[rq] device numbers,
+.RI ( n " + 128)."
+Devices opened using the principal device number will be sent a
+.B REWIND
+command when they are closed.
+Devices opened using the \[lq]no-rewind\[rq] device number will not.
+(Note that using an auto-rewind device for positioning the tape with,
+for instance, mt does not lead to the desired result: the tape is
+rewound after the mt command and the next command starts from the
+beginning of the tape).
+.P
+Within each group, four minor numbers are available to define
+devices with different characteristics (block size, compression,
+density, etc.)
+When the system starts up, only the first device is available.
+The other three are activated when the default
+characteristics are defined (see below).
+(By changing compile-time
+constants, it is possible to change the balance between the maximum
+number of tape drives and the number of minor numbers for each
+drive.
+The default allocation allows control of 32 tape drives.
+For instance, it is possible to control up to 64 tape drives
+with two minor numbers for different options.)
+.P
+Devices are typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 666 /dev/st0 c 9 0
+mknod \-m 666 /dev/st0l c 9 32
+mknod \-m 666 /dev/st0m c 9 64
+mknod \-m 666 /dev/st0a c 9 96
+mknod \-m 666 /dev/nst0 c 9 128
+mknod \-m 666 /dev/nst0l c 9 160
+mknod \-m 666 /dev/nst0m c 9 192
+mknod \-m 666 /dev/nst0a c 9 224
+.EE
+.in
+.P
+There is no corresponding block device.
+.P
+The driver uses an internal buffer that has to be large enough to hold
+at least one tape block.
+Before Linux 2.1.121, the buffer is
+allocated as one contiguous block.
+This limits the block size to the
+largest contiguous block of memory the kernel allocator can provide.
+The limit is currently 128\ kB for 32-bit architectures and
+256\ kB for 64-bit architectures.
+In newer kernels the driver
+allocates the buffer in several parts if necessary.
+By default, the
+maximum number of parts is 16.
+This means that the maximum block size
+is very large (2\ MB if allocation of 16 blocks of 128\ kB succeeds).
+.P
+The driver's internal buffer size is determined by a compile-time
+constant which can be overridden with a kernel startup option.
+In addition to this, the driver tries to allocate a larger temporary
+buffer at run time if necessary.
+However, run-time allocation of large
+contiguous blocks of memory may fail and it is advisable not to rely
+too much on dynamic buffer allocation before Linux 2.1.121
+(this applies also to demand-loading the driver with kerneld or kmod).
+.P
+The driver does not specifically support any tape drive brand or
+model.
+After system start-up the tape device options are defined by
+the drive firmware.
+For example, if the drive firmware selects fixed-block mode,
+the tape device uses fixed-block mode.
+The options can
+be changed with explicit
+.BR ioctl (2)
+calls and remain in effect when the device is closed and reopened.
+Setting the options affects both the auto-rewind and the nonrewind
+device.
+.P
+Different options can be specified for the different devices within
+the subgroup of four.
+The options take effect when the device is
+opened.
+For example, the system administrator can define
+one device that writes in fixed-block mode with a certain block size,
+and one which writes in variable-block mode (if the drive supports
+both modes).
+.P
+The driver supports
+.B tape partitions
+if they are supported by the drive.
+(Note that the tape partitions
+have nothing to do with disk partitions.
+A partitioned tape can be
+seen as several logical tapes within one medium.)
+Partition support has to be enabled with an
+.BR ioctl (2).
+The tape
+location is preserved within each partition across partition changes.
+The partition used for subsequent tape operations is
+selected with an
+.BR ioctl (2).
+The partition switch is executed together with
+the next tape operation in order to avoid unnecessary tape
+movement.
+The maximum number of partitions on a tape is defined by a
+compile-time constant (originally four).
+The driver contains an
+.BR ioctl (2)
+that can format a tape with either one or two partitions.
+.P
+Device
+.I /dev/tape
+is usually created as a hard or soft link to the default tape device
+on the system.
+.P
+Starting from Linux 2.6.2, the driver exports in the sysfs directory
+.I /sys/class/scsi_tape
+the attached devices and some parameters assigned to the devices.
+.SS Data transfer
+The driver supports operation in both fixed-block mode and
+variable-block mode (if supported by the drive).
+In fixed-block mode the drive
+writes blocks of the specified size and the block size is not
+dependent on the byte counts of the write system calls.
+In variable-block mode one tape block is written for each write call
+and the byte
+count determines the size of the corresponding tape block.
+Note that
+the blocks on the tape don't contain any information about the
+writing mode: when reading, the only important thing is to use
+commands that accept the block sizes on the tape.
+.P
+In variable-block mode the read byte count does not have to match
+the tape block size exactly.
+If the byte count is larger than the
+next block on tape, the driver returns the data and the function
+returns the actual block size.
+If the block size is larger than the
+byte count, an error is returned.
+.P
+In fixed-block mode the read byte counts can be arbitrary if
+buffering is enabled, or a multiple of the tape block size if
+buffering is disabled.
+Before Linux 2.1.121 allow writes with
+arbitrary byte count if buffering is enabled.
+In all other cases
+(before Linux 2.1.121 with buffering disabled or newer kernel) the
+write byte count must be a multiple of the tape block size.
+.P
+In Linux 2.6, the driver tries to use direct transfers between the user
+buffer and the device.
+If this is not possible, the driver's internal buffer
+is used.
+The reasons for not using direct transfers include improper alignment
+of the user buffer (default is 512 bytes but this can be changed by the HBA
+driver), one or more pages of the user buffer not reachable by the
+SCSI adapter, and so on.
+.P
+A filemark is automatically written to tape if the last tape operation
+before close was a write.
+.P
+When a filemark is encountered while reading, the following
+happens.
+If there are data remaining in the buffer when the filemark
+is found, the buffered data is returned.
+The next read returns zero
+bytes.
+The following read returns data from the next file.
+The end of
+recorded data is signaled by returning zero bytes for two consecutive
+read calls.
+The third read returns an error.
+.SS Ioctls
+The driver supports three
+.BR ioctl (2)
+requests.
+Requests not recognized by the
+.B st
+driver are passed to the
+.B SCSI
+driver.
+The definitions below are from
+.IR /usr/include/linux/mtio.h :
+.SS MTIOCTOP \[em] perform a tape operation
+This request takes an argument of type
+.IR "(struct mtop\ *)" .
+Not all drives support all operations.
+The driver returns an
+.B EIO
+error if the drive rejects an operation.
+.P
+.in +4n
+.EX
+/* Structure for MTIOCTOP \- mag tape op command: */
+struct mtop {
+    short   mt_op;       /* operations defined below */
+    int     mt_count;    /* how many of them */
+};
+.EE
+.in
+.P
+Magnetic tape operations for normal tape use:
+.TP
+.B MTBSF
+Backward space over
+.I mt_count
+filemarks.
+.TP
+.B MTBSFM
+Backward space over
+.I mt_count
+filemarks.
+Reposition the tape to the EOT side of the last filemark.
+.TP
+.B MTBSR
+Backward space over
+.I mt_count
+records (tape blocks).
+.TP
+.B MTBSS
+Backward space over
+.I mt_count
+setmarks.
+.TP
+.B MTCOMPRESSION
+Enable compression of tape data within the drive if
+.I mt_count
+is nonzero and disable compression if
+.I mt_count
+is zero.
+This command uses the MODE page 15 supported by most DATs.
+.TP
+.B MTEOM
+Go to the end of the recorded media (for appending files).
+.TP
+.B MTERASE
+Erase tape.
+With Linux 2.6, short erase (mark tape empty) is performed if the
+argument is zero.
+Otherwise, long erase (erase all) is done.
+.TP
+.B MTFSF
+Forward space over
+.I mt_count
+filemarks.
+.TP
+.B MTFSFM
+Forward space over
+.I mt_count
+filemarks.
+Reposition the tape to the BOT side of the last filemark.
+.TP
+.B MTFSR
+Forward space over
+.I mt_count
+records (tape blocks).
+.TP
+.B MTFSS
+Forward space over
+.I mt_count
+setmarks.
+.TP
+.B MTLOAD
+Execute the SCSI load command.
+A special case is available for some HP
+autoloaders.
+If
+.I mt_count
+is the constant
+.B MT_ST_HPLOADER_OFFSET
+plus a number, the number is
+sent to the drive to control the autoloader.
+.TP
+.B MTLOCK
+Lock the tape drive door.
+.TP
+.B MTMKPART
+Format the tape into one or two partitions.
+If
+.I mt_count
+is positive, it gives the size of partition 1 and partition
+0 contains the rest of the tape.
+If
+.I mt_count
+is zero, the tape is formatted into one partition.
+From Linux 4.6,
+.\" commit 8038e6456a3e6f5c4759e0d73c4f9165b90c93e7
+a negative
+.I mt_count
+specifies the size of partition 0 and
+the rest of the tape contains partition 1.
+The physical ordering of partitions depends on the drive.
+This command is not allowed for a drive unless the partition support
+is enabled for the drive (see
+.B MT_ST_CAN_PARTITIONS
+below).
+.TP
+.B MTNOP
+No op\[em]flushes the driver's buffer as a side effect.
+Should be used before reading status with
+.BR MTIOCGET .
+.TP
+.B MTOFFL
+Rewind and put the drive off line.
+.TP
+.B MTRESET
+Reset drive.
+.TP
+.B MTRETEN
+Re-tension tape.
+.TP
+.B MTREW
+Rewind.
+.TP
+.B MTSEEK
+Seek to the tape block number specified in
+.IR mt_count .
+This operation requires either a SCSI-2 drive that supports the
+.B LOCATE
+command (device-specific address)
+or a Tandberg-compatible SCSI-1 drive (Tandberg, Archive
+Viper, Wangtek, ...).
+The block number should be one that was previously returned by
+.B MTIOCPOS
+if device-specific addresses are used.
+.TP
+.B MTSETBLK
+Set the drive's block length to the value specified in
+.IR mt_count .
+A block length of zero sets the drive to variable block size mode.
+.TP
+.B MTSETDENSITY
+Set the tape density to the code in
+.IR mt_count .
+The density codes supported by a drive can be found from the drive
+documentation.
+.TP
+.B MTSETPART
+The active partition is switched to
+.IR mt_count .
+The partitions are numbered from zero.
+This command is not allowed for
+a drive unless the partition support is enabled for the drive (see
+.B MT_ST_CAN_PARTITIONS
+below).
+.TP
+.B MTUNLOAD
+Execute the SCSI unload command (does not eject the tape).
+.TP
+.B MTUNLOCK
+Unlock the tape drive door.
+.TP
+.B MTWEOF
+Write
+.I mt_count
+filemarks.
+.TP
+.B MTWSM
+Write
+.I mt_count
+setmarks.
+.P
+Magnetic tape operations for setting of device options (by the superuser):
+.TP
+.B MTSETDRVBUFFER
+Set various drive and driver options according to bits encoded in
+.IR mt_count .
+These consist of the drive's buffering mode, a set of Boolean driver
+options, the buffer write threshold, defaults for the block size and
+density, and timeouts (only since Linux 2.1).
+A single operation can affect only one item in the list below (the
+Booleans counted as one item.)
+.IP
+A value having zeros in the high-order 4 bits will be used to set the
+drive's buffering mode.
+The buffering modes are:
+.RS
+.TP
+.B 0
+The drive will not report
+.B GOOD
+status on write commands until the data
+blocks are actually written to the medium.
+.TP
+.B 1
+The drive may report
+.B GOOD
+status on write commands as soon as all the
+data has been transferred to the drive's internal buffer.
+.TP
+.B 2
+The drive may report
+.B GOOD
+status on write commands as soon as (a) all
+the data has been transferred to the drive's internal buffer, and
+(b) all buffered data from different initiators has been successfully
+written to the medium.
+.RE
+.IP
+To control the write threshold the value in
+.I mt_count
+must include the constant
+.B MT_ST_WRITE_THRESHOLD
+bitwise ORed with a block count in the low 28 bits.
+The block count refers to 1024-byte blocks, not the physical block
+size on the tape.
+The threshold cannot exceed the driver's internal buffer size (see
+DESCRIPTION, above).
+.IP
+To set and clear the Boolean options
+the value in
+.I mt_count
+must include one of the constants
+.BR MT_ST_BOOLEANS ,
+.BR MT_ST_SETBOOLEANS ,
+.BR MT_ST_CLEARBOOLEANS ,
+or
+.B MT_ST_DEFBOOLEANS
+bitwise ORed with
+whatever combination of the following options is desired.
+Using
+.B MT_ST_BOOLEANS
+the options can be set to the values
+defined in the corresponding bits.
+With
+.B MT_ST_SETBOOLEANS
+the options can be selectively set and with
+.B MT_ST_DEFBOOLEANS
+selectively cleared.
+.IP
+The default options for a tape device are set with
+.BR MT_ST_DEFBOOLEANS .
+A nonactive tape device (e.g., device with
+minor 32 or 160) is activated when the default options for it are
+defined the first time.
+An activated device inherits from the device
+activated at start-up the options not set explicitly.
+.IP
+The Boolean options are:
+.RS
+.TP
+.BR MT_ST_BUFFER_WRITES " (Default: true)"
+Buffer all write operations in fixed-block mode.
+If this option is false and the drive uses a fixed block size, then
+all write operations must be for a multiple of the block size.
+This option must be set false to write reliable multivolume archives.
+.TP
+.BR MT_ST_ASYNC_WRITES " (Default: true)"
+When this option is true, write operations return immediately without
+waiting for the data to be transferred to the drive if the data fits
+into the driver's buffer.
+The write threshold determines how full the buffer must be before a
+new SCSI write command is issued.
+Any errors reported by the drive will be held until the next
+operation.
+This option must be set false to write reliable multivolume archives.
+.TP
+.BR MT_ST_READ_AHEAD " (Default: true)"
+This option causes the driver to provide read buffering and
+read-ahead in fixed-block mode.
+If this option is false and the drive uses a fixed block size, then
+all read operations must be for a multiple of the block size.
+.TP
+.BR MT_ST_TWO_FM " (Default: false)"
+This option modifies the driver behavior when a file is closed.
+The normal action is to write a single filemark.
+If the option is true, the driver will write two filemarks and
+backspace over the second one.
+.IP
+Note:
+This option should not be set true for QIC tape drives since they are
+unable to overwrite a filemark.
+These drives detect the end of recorded data by testing for blank tape
+rather than two consecutive filemarks.
+Most other current drives also
+detect the end of recorded data and using two filemarks is usually
+necessary only when interchanging tapes with some other systems.
+.TP
+.BR MT_ST_DEBUGGING " (Default: false)"
+This option turns on various debugging messages from the driver
+(effective only if the driver was compiled with
+.B DEBUG
+defined nonzero).
+.TP
+.BR MT_ST_FAST_EOM " (Default: false)"
+This option causes the
+.B MTEOM
+operation to be sent directly to the
+drive, potentially speeding up the operation but causing the driver to
+lose track of the current file number normally returned by the
+.B MTIOCGET
+request.
+If
+.B MT_ST_FAST_EOM
+is false, the driver will respond to an
+.B MTEOM
+request by forward spacing over files.
+.TP
+.BR MT_ST_AUTO_LOCK " (Default: false)"
+When this option is true, the drive door is locked when the device file is
+opened and unlocked when it is closed.
+.TP
+.BR MT_ST_DEF_WRITES " (Default: false)"
+The tape options (block size, mode, compression, etc.) may change
+when changing from one device linked to a drive to another device
+linked to the same drive depending on how the devices are
+defined.
+This option defines when the changes are enforced by the
+driver using SCSI-commands and when the drives auto-detection
+capabilities are relied upon.
+If this option is false, the driver
+sends the SCSI-commands immediately when the device is changed.
+If the
+option is true, the SCSI-commands are not sent until a write is
+requested.
+In this case, the drive firmware is allowed to detect the
+tape structure when reading and the SCSI-commands are used only to
+make sure that a tape is written according to the correct specification.
+.TP
+.BR MT_ST_CAN_BSR " (Default: false)"
+When read-ahead is used, the tape must sometimes be spaced backward to the
+correct position when the device is closed and the SCSI command to
+space backward over records is used for this purpose.
+Some older
+drives can't process this command reliably and this option can be used
+to instruct the driver not to use the command.
+The end result is that,
+with read-ahead and fixed-block mode, the tape may not be correctly
+positioned within a file when the device is closed.
+With Linux 2.6, the
+default is true for drives supporting SCSI-3.
+.TP
+.BR MT_ST_NO_BLKLIMS " (Default: false)"
+Some drives don't accept the
+.B "READ BLOCK LIMITS"
+SCSI command.
+If this is used, the driver does not use the command.
+The drawback is
+that the driver can't check before sending commands if the selected
+block size is acceptable to the drive.
+.TP
+.BR MT_ST_CAN_PARTITIONS " (Default: false)"
+This option enables support for several partitions within a
+tape.
+The option applies to all devices linked to a drive.
+.TP
+.BR MT_ST_SCSI2LOGICAL " (Default: false)"
+This option instructs the driver to use the logical block addresses
+defined in the SCSI-2 standard when performing the seek and tell
+operations (both with
+.B MTSEEK
+and
+.B MTIOCPOS
+commands and when changing tape
+partition).
+Otherwise, the device-specific addresses are used.
+It is highly advisable to set this option if the drive supports the
+logical addresses because they count also filemarks.
+There are some
+drives that support only the logical block addresses.
+.TP
+.BR MT_ST_SYSV " (Default: false)"
+When this option is enabled, the tape devices use the System V
+semantics.
+Otherwise, the BSD semantics are used.
+The most important
+difference between the semantics is what happens when a device used
+for reading is closed: in System V semantics the tape is spaced forward
+past the next filemark if this has not happened while using the
+device.
+In BSD semantics the tape position is not changed.
+.TP
+.BR MT_NO_WAIT " (Default: false)"
+Enables immediate mode (i.e., don't wait for the command to finish) for some
+commands (e.g., rewind).
+.P
+An example:
+.P
+.in +4n
+.EX
+struct mtop mt_cmd;
+mt_cmd.mt_op = MTSETDRVBUFFER;
+mt_cmd.mt_count = MT_ST_BOOLEANS |
+        MT_ST_BUFFER_WRITES | MT_ST_ASYNC_WRITES;
+ioctl(fd, MTIOCTOP, mt_cmd);
+.EE
+.in
+.P
+The default block size for a device can be set with
+.B MT_ST_DEF_BLKSIZE
+and the default density code can be set with
+.BR MT_ST_DEFDENSITY .
+The values for the parameters are or'ed
+with the operation code.
+.P
+With Linux 2.1.x and later, the timeout values can be set with the
+subcommand
+.B MT_ST_SET_TIMEOUT
+ORed with the timeout in seconds.
+The long timeout (used for rewinds and other commands
+that may take a long time) can be set with
+.BR MT_ST_SET_LONG_TIMEOUT .
+The kernel defaults are very long to
+make sure that a successful command is not timed out with any
+drive.
+Because of this, the driver may seem stuck even if it is only
+waiting for the timeout.
+These commands can be used to set more
+practical values for a specific drive.
+The timeouts set for one device
+apply for all devices linked to the same drive.
+.P
+Starting from Linux 2.4.19 and Linux 2.5.43, the driver supports a status
+bit which indicates whether the drive requests cleaning.
+The method used by the
+drive to return cleaning information is set using the
+.B MT_ST_SEL_CLN
+subcommand.
+If the value is zero, the cleaning
+bit is always zero.
+If the value is one, the TapeAlert data defined
+in the SCSI-3 standard is used (not yet implemented).
+Values 2\[en]17 are
+reserved.
+If the lowest eight bits are >= 18, bits from the extended
+sense data are used.
+The bits 9\[en]16 specify a mask to select the bits
+to look at and the bits 17\[en]23 specify the bit pattern to look for.
+If the bit pattern is zero, one or more bits under the mask indicate
+the cleaning request.
+If the pattern is nonzero, the pattern must match
+the masked sense data byte.
+.RE
+.SS MTIOCGET \[em] get status
+This request takes an argument of type
+.IR "(struct mtget\ *)" .
+.P
+.in +4n
+.EX
+/* structure for MTIOCGET \- mag tape get status command */
+struct mtget {
+    long     mt_type;
+    long     mt_resid;
+    /* the following registers are device dependent */
+    long     mt_dsreg;
+    long     mt_gstat;
+    long     mt_erreg;
+    /* The next two fields are not always used */
+    daddr_t  mt_fileno;
+    daddr_t  mt_blkno;
+};
+.EE
+.in
+.TP
+\fImt_type\fP
+The header file defines many values for
+.IR mt_type ,
+but the current driver reports only the generic types
+.B MT_ISSCSI1
+(Generic SCSI-1 tape)
+and
+.B MT_ISSCSI2
+(Generic SCSI-2 tape).
+.TP
+\fImt_resid\fP
+contains the current tape partition number.
+.TP
+\fImt_dsreg\fP
+reports the drive's current settings for block size (in the low 24
+bits) and density (in the high 8 bits).
+These fields are defined by
+.BR MT_ST_BLKSIZE_SHIFT ,
+.BR MT_ST_BLKSIZE_MASK ,
+.BR MT_ST_DENSITY_SHIFT ,
+and
+.BR MT_ST_DENSITY_MASK .
+.TP
+\fImt_gstat\fP
+reports generic (device independent) status information.
+The header file defines macros for testing these status bits:
+.RS
+.TP
+\fBGMT_EOF\fP(\fIx\fP)
+The tape is positioned just after a filemark
+(always false after an
+.B MTSEEK
+operation).
+.TP
+\fBGMT_BOT\fP(\fIx\fP)
+The tape is positioned at the beginning of the first file (always false
+after an
+.B MTSEEK
+operation).
+.TP
+\fBGMT_EOT\fP(\fIx\fP)
+A tape operation has reached the physical End Of Tape.
+.TP
+\fBGMT_SM\fP(\fIx\fP)
+The tape is currently positioned at a setmark
+(always false after an
+.B MTSEEK
+operation).
+.TP
+\fBGMT_EOD\fP(\fIx\fP)
+The tape is positioned at the end of recorded data.
+.TP
+\fBGMT_WR_PROT\fP(\fIx\fP)
+The drive is write-protected.
+For some drives this can also mean that the drive does not support
+writing on the current medium type.
+.TP
+\fBGMT_ONLINE\fP(\fIx\fP)
+The last
+.BR open (2)
+found the drive with a tape in place and ready for operation.
+.TP
+\fBGMT_D_6250\fP(\fIx\fP)
+.TQ
+\fBGMT_D_1600\fP(\fIx\fP)
+.TQ
+\fBGMT_D_800\fP(\fIx\fP)
+This \[lq]generic\[rq] status information reports the current
+density setting for 9-track \(12" tape drives only.
+.TP
+\fBGMT_DR_OPEN\fP(\fIx\fP)
+The drive does not have a tape in place.
+.TP
+\fBGMT_IM_REP_EN\fP(\fIx\fP)
+Immediate report mode.
+This bit is set if there are no guarantees that
+the data has been physically written to the tape when the write call
+returns.
+It is set zero only when the driver does not buffer data and
+the drive is set not to buffer data.
+.TP
+\fBGMT_CLN\fP(\fIx\fP)
+The drive has requested cleaning.
+Implemented since Linux 2.4.19 and Linux 2.5.43.
+.RE
+.TP
+\fImt_erreg\fP
+The only field defined in
+.I mt_erreg
+is the recovered error count in the low 16 bits (as defined by
+.B MT_ST_SOFTERR_SHIFT
+and
+.BR MT_ST_SOFTERR_MASK ).
+Due to inconsistencies in the way drives report recovered errors, this
+count is often not maintained (most drives do not by default report
+soft errors but this can be changed with a SCSI MODE SELECT command).
+.TP
+\fImt_fileno\fP
+reports the current file number (zero-based).
+This value is set to \-1 when the file number is unknown (e.g., after
+.B MTBSS
+or
+.BR MTSEEK ).
+.TP
+\fImt_blkno\fP
+reports the block number (zero-based) within the current file.
+This value is set to \-1 when the block number is unknown (e.g., after
+.BR MTBSF ,
+.BR MTBSS ,
+or
+.BR MTSEEK ).
+.SS MTIOCPOS \[em] get tape position
+This request takes an argument of type
+.I "(struct mtpos\ *)"
+and reports the drive's notion of the current tape block number,
+which is not the same as
+.I mt_blkno
+returned by
+.BR MTIOCGET .
+This drive must be a SCSI-2 drive that supports the
+.B "READ POSITION"
+command (device-specific address)
+or a Tandberg-compatible SCSI-1 drive (Tandberg, Archive
+Viper, Wangtek, ... ).
+.P
+.in +4n
+.EX
+/* structure for MTIOCPOS \- mag tape get position command */
+struct mtpos {
+    long mt_blkno;    /* current block number */
+};
+.EE
+.in
+.SH RETURN VALUE
+.TP
+.B EACCES
+An attempt was made to write or erase a write-protected tape.
+(This error is not detected during
+.BR open (2).)
+.TP
+.B EBUSY
+The device is already in use or the driver was unable to allocate a
+buffer.
+.TP
+.B EFAULT
+The command parameters point to memory not belonging to the calling
+process.
+.TP
+.B EINVAL
+An
+.BR ioctl (2)
+had an invalid argument, or a requested block size was invalid.
+.TP
+.B EIO
+The requested operation could not be completed.
+.TP
+.B ENOMEM
+The byte count in
+.BR read (2)
+is smaller than the next physical block on the tape.
+(Before Linux 2.2.18 and Linux 2.4.0 the extra bytes have been
+.\" Precisely: Linux 2.6.0-test6
+silently ignored.)
+.TP
+.B ENOSPC
+A write operation could not be completed because the tape reached
+end-of-medium.
+.TP
+.B ENOSYS
+Unknown
+.BR ioctl (2).
+.TP
+.B ENXIO
+During opening, the tape device does not exist.
+.TP
+.B EOVERFLOW
+An attempt was made to read or write a variable-length block that is
+larger than the driver's internal buffer.
+.TP
+.B EROFS
+Open is attempted with
+.B O_WRONLY
+or
+.B O_RDWR
+when the tape in the drive is write-protected.
+.SH FILES
+.TP
+.I /dev/st*
+the auto-rewind SCSI tape devices
+.TP
+.I /dev/nst*
+the nonrewind SCSI tape devices
+.\" .SH AUTHOR
+.\" The driver has been written by Kai M\(:akisara (Kai.Makisara@metla.fi)
+.\" starting from a driver written by Dwayne Forsyth.
+.\" Several other
+.\" people have also contributed to the driver.
+.SH NOTES
+.IP \[bu] 3
+When exchanging data between systems, both systems have to agree on
+the physical tape block size.
+The parameters of a drive after startup
+are often not the ones most operating systems use with these
+devices.
+Most systems use drives in variable-block mode if the drive
+supports that mode.
+This applies to most modern drives, including
+DATs, 8mm helical scan drives, DLTs, etc.
+It may be advisable to use
+these drives in variable-block mode also in Linux (i.e., use
+.B MTSETBLK
+or
+.B MTSETDEFBLK
+at system startup to set the mode), at least when
+exchanging data with a foreign system.
+The drawback of
+this is that a fairly large tape block size has to be used to get
+acceptable data transfer rates on the SCSI bus.
+.IP \[bu]
+Many programs (e.g.,
+.BR tar (1))
+allow the user to specify the blocking
+factor on the command line.
+Note that this determines the physical block
+size on tape only in variable-block mode.
+.IP \[bu]
+In order to use SCSI tape drives, the basic SCSI driver,
+a SCSI-adapter driver and the SCSI tape driver must be either
+configured into the kernel or loaded as modules.
+If the SCSI-tape
+driver is not present, the drive is recognized but the tape support
+described in this page is not available.
+.IP \[bu]
+The driver writes error messages to the console/log.
+The SENSE
+codes written into some messages are automatically translated to text
+if verbose SCSI messages are enabled in kernel configuration.
+.IP \[bu]
+The driver's internal buffering allows good throughput in fixed-block
+mode also with small
+.BR read (2)
+and
+.BR write (2)
+byte counts.
+With direct transfers
+this is not possible and may cause a surprise when moving to the 2.6
+kernel.
+The solution is to tell the software to use larger transfers (often
+telling it to use larger blocks).
+If this is not possible, direct transfers can be disabled.
+.SH SEE ALSO
+.BR mt (1)
+.P
+The file
+.I drivers/scsi/README.st
+or
+.I Documentation/scsi/st.txt
+(kernel >= 2.6) in the Linux kernel source tree contains
+the most recent information about the driver and its configuration
+possibilities
diff --git a/man/man4/tty.4 b/man/man4/tty.4
new file mode 100644
index 000000000..7a0d214b6
--- /dev/null
+++ b/man/man4/tty.4
@@ -0,0 +1,67 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 2003-04-07 by Michael Kerrisk
+.\"
+.TH tty 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tty \- controlling terminal
+.SH DESCRIPTION
+The file
+.I /dev/tty
+is a character file with major number 5 and
+minor number 0, usually with mode 0666 and ownership root:tty.
+It is a synonym for the controlling terminal of a process, if any.
+.P
+In addition to the
+.BR ioctl (2)
+requests supported by the device that
+.B tty
+refers to, the
+.BR ioctl (2)
+request
+.B TIOCNOTTY
+is supported.
+.SS TIOCNOTTY
+Detach the calling process from its controlling terminal.
+.P
+If the process is the session leader,
+then
+.B SIGHUP
+and
+.B SIGCONT
+signals are sent to the foreground process group
+and all processes in the current session lose their controlling tty.
+.P
+This
+.BR ioctl (2)
+call works only on file descriptors connected
+to
+.IR /dev/tty .
+It is used by daemon processes when they are invoked
+by a user at a terminal.
+The process attempts to open
+.IR /dev/tty .
+If the open succeeds, it
+detaches itself from the terminal by using
+.BR TIOCNOTTY ,
+while if the
+open fails, it is obviously not attached to a terminal and does not need
+to detach itself.
+.SH FILES
+.I /dev/tty
+.SH SEE ALSO
+.BR chown (1),
+.BR mknod (1),
+.BR ioctl (2),
+.BR ioctl_console (2),
+.BR ioctl_tty (2),
+.BR termios (3),
+.BR ttyS (4),
+.BR vcs (4),
+.BR pty (7),
+.BR agetty (8),
+.BR mingetty (8)
diff --git a/man/man4/ttyS.4 b/man/man4/ttyS.4
new file mode 100644
index 000000000..dcab5ca4a
--- /dev/null
+++ b/man/man4/ttyS.4
@@ -0,0 +1,33 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:03:24 1993 by Rik Faith (faith@cs.unc.edu)
+.TH ttyS 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ttyS \- serial terminal lines
+.SH DESCRIPTION
+.B ttyS[0\-3]
+are character devices for the serial terminal lines.
+.P
+They are typically created by:
+.P
+.in +4n
+.EX
+mknod \-m 660 /dev/ttyS0 c 4 64 # base address 0x3f8
+mknod \-m 660 /dev/ttyS1 c 4 65 # base address 0x2f8
+mknod \-m 660 /dev/ttyS2 c 4 66 # base address 0x3e8
+mknod \-m 660 /dev/ttyS3 c 4 67 # base address 0x2e8
+chown root:tty /dev/ttyS[0\-3]
+.EE
+.in
+.SH FILES
+.I /dev/ttyS[0\-3]
+.SH SEE ALSO
+.BR chown (1),
+.BR mknod (1),
+.BR tty (4),
+.BR agetty (8),
+.BR mingetty (8),
+.BR setserial (8)
diff --git a/man/man4/tty_ioctl.4 b/man/man4/tty_ioctl.4
new file mode 100644
index 000000000..fc4736ed0
--- /dev/null
+++ b/man/man4/tty_ioctl.4
@@ -0,0 +1,2 @@
+.so man2/ioctl_tty.2
+.\" Link for old name of this page
diff --git a/man/man4/urandom.4 b/man/man4/urandom.4
new file mode 100644
index 000000000..b95979fa8
--- /dev/null
+++ b/man/man4/urandom.4
@@ -0,0 +1 @@
+.so man4/random.4
diff --git a/man/man4/vcs.4 b/man/man4/vcs.4
new file mode 100644
index 000000000..fe159f093
--- /dev/null
+++ b/man/man4/vcs.4
@@ -0,0 +1,172 @@
+.\" Copyright (c) 1995 James R. Van Zandt <jrv@vanzandt.mv.com>
+.\" Sat Feb 18 09:11:07 EST 1995
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified, Sun Feb 26 15:08:05 1995, faith@cs.unc.edu
+.\" 2007-12-17, Samuel Thibault <samuel.thibault@ens-lyon.org>:
+.\"     document the VT_GETHIFONTMASK ioctl
+.\" "
+.TH vcs 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+vcs, vcsa \- virtual console memory
+.SH DESCRIPTION
+.I /dev/vcs0
+is a character device with major number 7 and minor number
+0, usually with mode 0644 and ownership root:tty.
+It refers to the memory of the currently
+displayed virtual console terminal.
+.P
+.I /dev/vcs[1\-63]
+are character devices for virtual console
+terminals, they have major number 7 and minor number 1 to 63, usually
+mode 0644 and ownership root:tty.
+.I /dev/vcsa[0\-63]
+are the same, but
+using
+.IR "unsigned short" s
+(in host byte order) that include attributes,
+and prefixed with four bytes giving the screen
+dimensions and cursor position:
+.IR lines ,
+.IR columns ,
+.IR x ,
+.IR y .
+.RI ( x
+=
+.I y
+= 0 at the top left corner of the screen.)
+.P
+When a 512-character font is loaded,
+the 9th bit position can be fetched by applying the
+.BR ioctl (2)
+.B VT_GETHIFONTMASK
+operation
+(available since Linux 2.6.18)
+on
+.IR /dev/tty[1\-63] ;
+the value is returned in the
+.I "unsigned short"
+pointed to by the third
+.BR ioctl (2)
+argument.
+.P
+These devices replace the screendump
+.BR ioctl (2)
+operations of
+.BR ioctl_console (2),
+so the system
+administrator can control access using filesystem permissions.
+.P
+The devices for the first eight virtual consoles may be created by:
+.P
+.in +4n
+.EX
+for x in 0 1 2 3 4 5 6 7 8; do
+    mknod \-m 644 /dev/vcs$x c 7 $x;
+    mknod \-m 644 /dev/vcsa$x c 7 $[$x+128];
+done
+chown root:tty /dev/vcs*
+.EE
+.in
+.P
+No
+.BR ioctl (2)
+requests are supported.
+.SH FILES
+.I /dev/vcs[0\-63]
+.br
+.I /dev/vcsa[0\-63]
+.\" .SH AUTHOR
+.\" Andries Brouwer <aeb@cwi.nl>
+.SH VERSIONS
+Introduced with Linux 1.1.92.
+.SH EXAMPLES
+You may do a screendump on vt3 by switching to vt1 and typing
+.P
+.in +4n
+.EX
+cat /dev/vcs3 >foo
+.EE
+.in
+.P
+Note that the output does not contain
+newline characters, so some processing may be required, like
+in
+.P
+.in +4n
+.EX
+fold \-w 81 /dev/vcs3 | lpr
+.EE
+.in
+.P
+or (horrors)
+.P
+.in +4n
+.EX
+setterm \-dump 3 \-file /proc/self/fd/1
+.EE
+.in
+.P
+The
+.I /dev/vcsa0
+device is used for Braille support.
+.P
+This program displays the character and screen attributes under the
+cursor of the second virtual console, then changes the background color
+there:
+.P
+.EX
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/vt.h>
+\&
+int
+main(void)
+{
+    int fd;
+    char *device = "/dev/vcsa2";
+    char *console = "/dev/tty2";
+    struct {unsigned char lines, cols, x, y;} scrn;
+    unsigned short s;
+    unsigned short mask;
+    unsigned char attrib;
+    int ch;
+\&
+    fd = open(console, O_RDWR);
+    if (fd < 0) {
+        perror(console);
+        exit(EXIT_FAILURE);
+    }
+    if (ioctl(fd, VT_GETHIFONTMASK, &mask) < 0) {
+        perror("VT_GETHIFONTMASK");
+        exit(EXIT_FAILURE);
+    }
+    (void) close(fd);
+    fd = open(device, O_RDWR);
+    if (fd < 0) {
+        perror(device);
+        exit(EXIT_FAILURE);
+    }
+    (void) read(fd, &scrn, 4);
+    (void) lseek(fd, 4 + 2*(scrn.y*scrn.cols + scrn.x), SEEK_SET);
+    (void) read(fd, &s, 2);
+    ch = s & 0xff;
+    if (s & mask)
+        ch |= 0x100;
+    attrib = ((s & \[ti]mask) >> 8);
+    printf("ch=%#03x attrib=%#02x\en", ch, attrib);
+    s \[ha]= 0x1000;
+    (void) lseek(fd, \-2, SEEK_CUR);
+    (void) write(fd, &s, 2);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR ioctl_console (2),
+.BR tty (4),
+.BR ttyS (4),
+.BR gpm (8)
diff --git a/man/man4/vcsa.4 b/man/man4/vcsa.4
new file mode 100644
index 000000000..ffe8d9be5
--- /dev/null
+++ b/man/man4/vcsa.4
@@ -0,0 +1 @@
+.so man4/vcs.4
diff --git a/man/man4/veth.4 b/man/man4/veth.4
new file mode 100644
index 000000000..690a2087e
--- /dev/null
+++ b/man/man4/veth.4
@@ -0,0 +1,86 @@
+.\" Copyright (c) 2012 Tomáš Pospíšek (tpo_deb@sourcepole.ch),
+.\"     Fri, 03 Nov 2012 22:35:33 +0100
+.\" and Copyright (c) 2012 Eric W. Biederman <ebiederm@xmission.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\"
+.TH veth 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+veth \- Virtual Ethernet Device
+.SH DESCRIPTION
+The
+.B veth
+devices are virtual Ethernet devices.
+They can act as tunnels between network namespaces to create
+a bridge to a physical network device in another namespace,
+but can also be used as standalone network devices.
+.P
+.B veth
+devices are always created in interconnected pairs.
+A pair can be created using the command:
+.P
+.in +4n
+.EX
+# ip link add <p1-name> type veth peer name <p2-name>
+.EE
+.in
+.P
+In the above,
+.I p1-name
+and
+.I p2-name
+are the names assigned to the two connected end points.
+.P
+Packets transmitted on one device in the pair are immediately received on
+the other device.
+When either device is down, the link state of the pair is down.
+.P
+.B veth
+device pairs are useful for combining the network
+facilities of the kernel together in interesting ways.
+A particularly interesting use case is to place one end of a
+.B veth
+pair in one network namespace and the other end in another network namespace,
+thus allowing communication between network namespaces.
+To do this, one can provide the
+.B netns
+parameter when creating the interfaces:
+.P
+.in +4n
+.EX
+# ip link add <p1\-name> netns <p1\-ns> type veth peer <p2\-name> netns <p2\-ns>
+.EE
+.in
+.P
+or, for an existing
+.B veth
+pair, move one side to the other namespace:
+.P
+.in +4n
+.EX
+# ip link set <p2\-name> netns <p2\-ns>
+.EE
+.in
+.P
+.BR ethtool (8)
+can be used to find the peer of a
+.B veth
+network interface, using commands something like:
+.P
+.in +4n
+.EX
+# \fBip link add ve_A type veth peer name ve_B\fP   # Create veth pair
+# \fBethtool \-S ve_A\fP         # Discover interface index of peer
+NIC statistics:
+     peer_ifindex: 16
+# \fBip link | grep \[aq]\[ha]16:\[aq]\fP   # Look up interface
+16: ve_B@ve_A: <BROADCAST,MULTICAST,M\-DOWN> mtu 1500 qdisc ...
+.EE
+.in
+.SH "SEE ALSO"
+.BR clone (2),
+.BR network_namespaces (7),
+.BR ip (8),
+.BR ip\-link (8),
+.BR ip\-netns (8)
diff --git a/man/man4/wavelan.4 b/man/man4/wavelan.4
new file mode 100644
index 000000000..ad2532cbc
--- /dev/null
+++ b/man/man4/wavelan.4
@@ -0,0 +1,142 @@
+.\" From jt@hplb.hpl.hp.com Thu Dec 19 18:31:49 1996
+.\" From: Jean Tourrilhes <jt@hplb.hpl.hp.com>
+.\" Address: HP Labs, Filton Road, Stoke Gifford, Bristol BS12 6QZ, U.K.
+.\" Jean II - HPLB - '96
+.\" wavelan.c.4
+.\"
+.\" Provenance of this page is unclear.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH wavelan 4 (date) "Linux man-pages (unreleased)"
+.SH NAME
+wavelan \- AT&T GIS WaveLAN ISA device driver
+.SH SYNOPSIS
+.nf
+.BI "insmod wavelan_cs.o [io=" B,B.. "] [ irq=" I,I.. "] [name=" N,N.. ]
+.fi
+.SH DESCRIPTION
+.I This driver is obsolete:
+it was removed in Linux 2.6.35.
+.P
+.B wavelan
+is the low-level device driver for the NCR / AT&T / Lucent
+.B WaveLAN ISA
+and Digital (DEC)
+.B RoamAbout DS
+wireless ethernet adapter.
+This driver is available as a module or
+might be compiled in the kernel.
+This driver supports multiple cards
+in both forms (up to 4) and allocates the next available ethernet
+device (eth0..eth#) for each card found, unless a device name is
+explicitly specified (see below).
+This device name will be reported
+in the kernel log file with the MAC address, NWID, and frequency used
+by the card.
+.SS Parameters
+This section applies to the module form (parameters passed on the
+.BR insmod (8)
+command line).
+If the driver is included in the kernel, use the
+.I ether=IRQ,IO,NAME
+syntax on the kernel command line.
+.TP
+.B io
+Specify the list of base addresses where to search for wavelan cards
+(setting by dip switch on the card).
+If you don't specify any io
+address, the driver will scan 0x390 and 0x3E0 addresses, which might
+conflict with other hardware...
+.TP
+.B irq
+Set the list of IRQs that each wavelan card should use (the value is
+saved in permanent storage for future use).
+.TP
+.B name
+Set the list of names to be used for each wavelan card device (name
+used by
+.BR ifconfig (8)).
+.SS Wireless extensions
+Use
+.BR iwconfig (8)
+to manipulate wireless extensions.
+.SS NWID (or domain)
+Set the network ID
+.RI [ 0
+to
+.IR FFFF ]
+or disable it
+.RI [ off ].
+As the NWID is stored in the card Permanent Storage Area, it will be
+reused at any further invocation of the driver.
+.SS Frequency & channels
+For the 2.4\ GHz 2.00 Hardware, you are able to set the frequency by
+specifying one of the 10 defined channels
+.RI ( 2.412,
+.I 2.422, 2.425, 2.4305, 2.432, 2.442, 2.452, 2.460, 2.462
+or
+.IR 2.484 )
+or directly as a numeric value.
+The frequency is changed immediately and
+permanently.
+Frequency availability depends on the regulations...
+.SS Statistics spy
+Set a list of MAC addresses in the driver (up to 8) and get the last
+quality of link for each of those (see
+.BR iwspy (8)).
+.SS /proc/net/wireless
+.I status
+is the status reported by the modem.
+.I Link quality
+reports the quality of the modulation on the air (direct sequence
+spread spectrum) [max = 16].
+.I Level
+and
+.I Noise
+refer to the signal level and noise level [max = 64].
+The
+.I crypt discarded packet
+and
+.I misc discarded packet
+counters are not implemented.
+.SS Private ioctl
+You may use
+.BR iwpriv (8)
+to manipulate private ioctls.
+.SS Quality and level threshold
+Enables you to define the quality and level threshold used by the
+modem (packet below that level are discarded).
+.SS Histogram
+This functionality makes it possible to set a number of
+signal level intervals and
+to count the number of packets received in each of those defined
+intervals.
+This distribution might be used to calculate the mean value
+and standard deviation of the signal level.
+.SS Specific notes
+This driver fails to detect some
+.B non-NCR/AT&T/Lucent
+Wavelan cards.
+If this happens for you, you must look in the source code on
+how to add your card to the detection routine.
+.P
+Some of the mentioned features are optional.
+You may enable or disable
+them by changing flags in the driver header and recompile.
+.\" .SH AUTHOR
+.\" Bruce Janson \[em] bruce@cs.usyd.edu.au
+.\" .br
+.\" Jean Tourrilhes \[em] jt@hplb.hpl.hp.com
+.\" .br
+.\" (and others; see source code for details)
+.\"
+.\" SEE ALSO part
+.\"
+.SH SEE ALSO
+.BR wavelan_cs (4),
+.BR ifconfig (8),
+.BR insmod (8),
+.BR iwconfig (8),
+.BR iwpriv (8),
+.BR iwspy (8)
diff --git a/man/man4/zero.4 b/man/man4/zero.4
new file mode 100644
index 000000000..15a39be05
--- /dev/null
+++ b/man/man4/zero.4
@@ -0,0 +1 @@
+.so man4/null.4
diff --git a/man/man5/acct.5 b/man/man5/acct.5
new file mode 100644
index 000000000..e9fa47b0d
--- /dev/null
+++ b/man/man5/acct.5
@@ -0,0 +1,161 @@
+.\" Copyright (C) 2008, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH acct 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+acct \- process accounting file
+.SH SYNOPSIS
+.nf
+.B #include <sys/acct.h>
+.fi
+.SH DESCRIPTION
+If the kernel is built with the process accounting option enabled
+.RB ( CONFIG_BSD_PROCESS_ACCT ),
+then calling
+.BR acct (2)
+starts process accounting, for example:
+.P
+.in +4n
+acct("/var/log/pacct");
+.in
+.P
+When process accounting is enabled, the kernel writes a record
+to the accounting file as each process on the system terminates.
+This record contains information about the terminated process,
+and is defined in
+.I <sys/acct.h>
+as follows:
+.P
+.in +4n
+.EX
+#define ACCT_COMM 16
+\&
+typedef u_int16_t comp_t;
+\&
+struct acct {
+    char ac_flag;           /* Accounting flags */
+    u_int16_t ac_uid;       /* Accounting user ID */
+    u_int16_t ac_gid;       /* Accounting group ID */
+    u_int16_t ac_tty;       /* Controlling terminal */
+    u_int32_t ac_btime;     /* Process creation time
+                               (seconds since the Epoch) */
+    comp_t    ac_utime;     /* User CPU time */
+    comp_t    ac_stime;     /* System CPU time */
+    comp_t    ac_etime;     /* Elapsed time */
+    comp_t    ac_mem;       /* Average memory usage (kB) */
+    comp_t    ac_io;        /* Characters transferred (unused) */
+    comp_t    ac_rw;        /* Blocks read or written (unused) */
+    comp_t    ac_minflt;    /* Minor page faults */
+    comp_t    ac_majflt;    /* Major page faults */
+    comp_t    ac_swaps;     /* Number of swaps (unused) */
+    u_int32_t ac_exitcode;  /* Process termination status
+                               (see wait(2)) */
+    char      ac_comm[ACCT_COMM+1];
+                            /* Command name (basename of last
+                               executed command; null\-terminated) */
+    char      ac_pad[\fIX\fP];    /* padding bytes */
+};
+\&
+enum {          /* Bits that may be set in ac_flag field */
+    AFORK = 0x01,           /* Has executed fork, but no exec */
+    ASU   = 0x02,           /* Used superuser privileges */
+    ACORE = 0x08,           /* Dumped core */
+    AXSIG = 0x10            /* Killed by a signal */
+};
+.EE
+.in
+.P
+The
+.I comp_t
+data type is a floating-point value consisting of a 3-bit, base-8 exponent,
+and a 13-bit mantissa.
+A value,
+.IR c ,
+of this type can be converted to a (long) integer as follows:
+.P
+.nf
+    v = (c & 0x1fff) << (((c >> 13) & 0x7) * 3);
+.fi
+.P
+The
+.IR ac_utime ,
+.IR ac_stime ,
+and
+.I ac_etime
+fields measure time in "clock ticks"; divide these values by
+.I sysconf(_SC_CLK_TCK)
+to convert them to seconds.
+.SS Version 3 accounting file format
+Since Linux 2.6.8,
+an optional alternative version of the accounting file can be produced
+if the
+.B CONFIG_BSD_PROCESS_ACCT_V3
+option is set when building the kernel.
+With this option is set,
+the records written to the accounting file contain additional fields,
+and the width of
+.I c_uid
+and
+.I ac_gid
+fields is widened from 16 to 32 bits
+(in line with the increased size of UID and GIDs in Linux 2.4 and later).
+The records are defined as follows:
+.P
+.in +4n
+.EX
+struct acct_v3 {
+    char      ac_flag;      /* Flags */
+    char      ac_version;   /* Always set to ACCT_VERSION (3) */
+    u_int16_t ac_tty;       /* Controlling terminal */
+    u_int32_t ac_exitcode;  /* Process termination status */
+    u_int32_t ac_uid;       /* Real user ID */
+    u_int32_t ac_gid;       /* Real group ID */
+    u_int32_t ac_pid;       /* Process ID */
+    u_int32_t ac_ppid;      /* Parent process ID */
+    u_int32_t ac_btime;     /* Process creation time */
+    float     ac_etime;     /* Elapsed time */
+    comp_t    ac_utime;     /* User CPU time */
+    comp_t    ac_stime;     /* System time */
+    comp_t    ac_mem;       /* Average memory usage (kB) */
+    comp_t    ac_io;        /* Characters transferred (unused) */
+    comp_t    ac_rw;        /* Blocks read or written
+                               (unused) */
+    comp_t    ac_minflt;    /* Minor page faults */
+    comp_t    ac_majflt;    /* Major page faults */
+    comp_t    ac_swaps;     /* Number of swaps (unused) */
+    char      ac_comm[ACCT_COMM]; /* Command name */
+};
+.EE
+.in
+.SH VERSIONS
+Although it is present on most systems, it is not standardized,
+and the details vary somewhat between systems.
+.SH STANDARDS
+None.
+.SH HISTORY
+glibc 2.6.
+.P
+Process accounting originated on BSD.
+.SH NOTES
+Records in the accounting file are ordered by termination time of
+the process.
+.P
+Up to and including Linux 2.6.9,
+a separate accounting record is written for each thread created using
+the NPTL threading library;
+since Linux 2.6.10,
+a single accounting record is written for the entire process
+on termination of the last thread in the process.
+.P
+The
+.I /proc/sys/kernel/acct
+file, described in
+.BR proc (5),
+defines settings that control the behavior of process accounting
+when disk space runs low.
+.SH SEE ALSO
+.BR lastcomm (1),
+.BR acct (2),
+.BR accton (8),
+.BR sa (8)
diff --git a/man/man5/charmap.5 b/man/man5/charmap.5
new file mode 100644
index 000000000..40a9ad673
--- /dev/null
+++ b/man/man5/charmap.5
@@ -0,0 +1,105 @@
+.\" Copyright (C) 1994  Jochen Hein (Hein@Student.TU-Clausthal.de)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH charmap 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+charmap \- character set description file
+.SH DESCRIPTION
+A character set description (charmap) defines all available characters
+and their encodings in a character set.
+.BR localedef (1)
+can use charmaps to create locale variants for different character sets.
+.SS Syntax
+The charmap file starts with a header that may consist of the
+following keywords:
+.TP
+.RI < code_set_name >
+is followed by the name of the character map.
+.TP
+.RI < comment_char >
+is followed by a character that will be used as the comment character
+for the rest of the file.
+It defaults to the number sign (#).
+.TP
+.RI < escape_char >
+is followed by a character that should be used as the escape character
+for the rest of the file to mark characters that should be interpreted
+in a special way.
+It defaults to the backslash (\e).
+.TP
+.RI < mb_cur_max >
+is followed by the maximum number of bytes for a character.
+The default value is 1.
+.TP
+.RI < mb_cur_min >
+is followed by the minimum number of bytes for a character.
+This value must be less than or equal than
+.RI < mb_cur_max >.
+If not specified, it defaults to
+.RI < mb_cur_max >.
+.P
+The character set definition section starts with the keyword
+.I CHARMAP
+in the first column.
+.P
+The following lines may have one of the two following forms to
+define the character set:
+.TP
+.RI < character >\  byte-sequence\ comment
+This form defines exactly one character and its byte sequence,
+.I comment
+being optional.
+.TP
+.RI < character >..< character >\  byte-sequence\ comment
+This form defines a character range and its byte sequence,
+.I comment
+being optional.
+.P
+The character set definition section ends with the string
+.IR "END CHARMAP" .
+.P
+The character set definition section may optionally be followed by a
+section to define widths of characters.
+.P
+The
+.I WIDTH_DEFAULT
+keyword can be used to define the default width for all characters
+not explicitly listed.
+The default character width is 1.
+.P
+The width section for individual characters starts with the keyword
+.I WIDTH
+in the first column.
+.P
+The following lines may have one of the two following forms to
+define the widths of the characters:
+.TP
+.RI < character >\  width
+This form defines the width of exactly one character.
+.TP
+.RI < character >...< character >\  width
+This form defines the width for all the characters in the range.
+.P
+The width definition section ends with the string
+.IR "END WIDTH" .
+.SH FILES
+.TP
+.I /usr/share/i18n/charmaps
+Usual default character map path.
+.SH STANDARDS
+POSIX.2.
+.SH EXAMPLES
+The Euro sign is defined as follows in the
+.I UTF\-8
+charmap:
+.P
+.nf
+<U20AC>     /xe2/x82/xac EURO SIGN
+.fi
+.SH SEE ALSO
+.BR iconv (1),
+.BR locale (1),
+.BR localedef (1),
+.BR locale (5),
+.BR charsets (7)
diff --git a/man/man5/core.5 b/man/man5/core.5
new file mode 100644
index 000000000..2fb7979da
--- /dev/null
+++ b/man/man5/core.5
@@ -0,0 +1,684 @@
+.\" Copyright (c) 2006, 2008 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH core 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+core \- core dump file
+.SH DESCRIPTION
+The default action of certain signals is to cause a process to terminate
+and produce a
+.IR "core dump file" ,
+a file containing an image of the process's memory at
+the time of termination.
+This image can be used in a debugger (e.g.,
+.BR gdb (1))
+to inspect the state of the program at the time that it terminated.
+A list of the signals which cause a process to dump core can be found in
+.BR signal (7).
+.P
+A process can set its soft
+.B RLIMIT_CORE
+resource limit to place an upper limit on the size of the core dump file
+that will be produced if it receives a "core dump" signal; see
+.BR getrlimit (2)
+for details.
+.P
+There are various circumstances in which a core dump file is
+not produced:
+.IP \[bu] 3
+The process does not have permission to write the core file.
+(By default, the core file is called
+.I core
+or
+.IR core.pid ,
+where
+.I pid
+is the ID of the process that dumped core,
+and is created in the current working directory.
+See below for details on naming.)
+Writing the core file fails if the directory in which
+it is to be created is not writable,
+or if a file with the same name exists and
+is not writable
+or is not a regular file
+(e.g., it is a directory or a symbolic link).
+.IP \[bu]
+A (writable, regular) file with the same name as would be used for the
+core dump already exists, but there is more than one hard link to that
+file.
+.IP \[bu]
+The filesystem where the core dump file would be created is full;
+or has run out of inodes; or is mounted read-only;
+or the user has reached their quota for the filesystem.
+.IP \[bu]
+The directory in which the core dump file is to be created does
+not exist.
+.IP \[bu]
+The
+.B RLIMIT_CORE
+(core file size) or
+.B RLIMIT_FSIZE
+(file size) resource limits for the process are set to zero; see
+.BR getrlimit (2)
+and the documentation of the shell's
+.I ulimit
+command
+.RI ( limit
+in
+.BR csh (1)).
+However,
+.B RLIMIT_CORE
+will be ignored if the system is configured to pipe core dumps to a program.
+.IP \[bu]
+The binary being executed by the process does not have read
+permission enabled.
+(This is a security measure to
+ensure that an executable whose contents are not readable
+does not produce a\[em]possibly readable\[em]core dump containing
+an image of the executable.)
+.IP \[bu]
+The process is executing a set-user-ID (set-group-ID) program
+that is owned by a user (group) other than the real user (group)
+ID of the process,
+or the process is executing a program that has file capabilities (see
+.BR capabilities (7)).
+(However, see the description of the
+.BR prctl (2)
+.B PR_SET_DUMPABLE
+operation, and the description of the
+.I /proc/sys/fs/suid_dumpable
+.\" FIXME . Perhaps relocate discussion of /proc/sys/fs/suid_dumpable
+.\" and PR_SET_DUMPABLE to this page?
+file in
+.BR proc (5).)
+.IP \[bu]
+.I /proc/sys/kernel/core_pattern
+is empty and
+.I /proc/sys/kernel/core_uses_pid
+contains the value 0.
+(These files are described below.)
+Note that if
+.I /proc/sys/kernel/core_pattern
+is empty and
+.I /proc/sys/kernel/core_uses_pid
+contains the value 1,
+core dump files will have names of the form
+.IR .pid ,
+and such files are hidden unless one uses the
+.BR ls (1)
+.I \-a
+option.
+.IP \[bu]
+(Since Linux 3.7)
+.\" commit 046d662f481830e652ac34cd112249adde16452a
+The kernel was configured without the
+.B CONFIG_COREDUMP
+option.
+.P
+In addition,
+a core dump may exclude part of the address space of the process if the
+.BR madvise (2)
+.B MADV_DONTDUMP
+flag was employed.
+.P
+On systems that employ
+.BR systemd (1)
+as the
+.I init
+framework, core dumps may instead be placed in a location determined by
+.BR systemd (1).
+See below for further details.
+.\"
+.SS Naming of core dump files
+By default, a core dump file is named
+.IR core ,
+but the
+.I /proc/sys/kernel/core_pattern
+file (since Linux 2.6 and 2.4.21)
+can be set to define a template that is used to name core dump files.
+The template can contain % specifiers which are substituted
+by the following values when a core file is created:
+.P
+.RS 4
+.PD 0
+.TP 4
+%%
+A single % character.
+.TP
+%c
+Core file size soft resource limit of crashing process (since Linux 2.6.24).
+.TP
+%d
+.\" Added in git commit 12a2b4b2241e318b4f6df31228e4272d2c2968a1
+Dump mode\[em]same as value returned by
+.BR prctl (2)
+.B PR_GET_DUMPABLE
+(since Linux 3.7).
+.TP
+%e
+The process or thread's
+.I comm
+value, which typically is the same as the executable filename
+(without path prefix, and truncated to a maximum of 15 characters),
+but may have been modified to be something different;
+see the discussion of
+.IR /proc/ pid /comm
+and
+.IR /proc/ pid /task/ tid /comm
+in
+.BR proc (5).
+.TP
+%E
+Pathname of executable,
+with slashes (\[aq]/\[aq]) replaced by exclamation marks (\[aq]!\[aq])
+(since Linux 3.0).
+.TP
+%g
+Numeric real GID of dumped process.
+.TP
+%h
+Hostname (same as \fInodename\fP returned by \fBuname\fP(2)).
+.TP
+%i
+TID of thread that triggered core dump,
+as seen in the PID namespace in which the thread resides
+.\" commit b03023ecbdb76c1dec86b41ed80b123c22783220
+(since Linux 3.18).
+.TP
+%I
+TID of thread that triggered core dump, as seen in the initial PID namespace
+.\" commit b03023ecbdb76c1dec86b41ed80b123c22783220
+(since Linux 3.18).
+.TP
+%p
+PID of dumped process,
+as seen in the PID namespace in which the process resides.
+.TP
+%P
+.\" Added in git commit 65aafb1e7484b7434a0c1d4c593191ebe5776a2f
+PID of dumped process, as seen in the initial PID namespace
+(since Linux 3.12).
+.TP
+%s
+Number of signal causing dump.
+.TP
+%t
+Time of dump, expressed as seconds since the
+Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.TP
+%u
+Numeric real UID of dumped process.
+.PD
+.RE
+.P
+A single % at the end of the template is dropped from the
+core filename, as is the combination of a % followed by any
+character other than those listed above.
+All other characters in the template become a literal
+part of the core filename.
+The template may include \[aq]/\[aq] characters, which are interpreted
+as delimiters for directory names.
+The maximum size of the resulting core filename is 128 bytes (64 bytes
+before Linux 2.6.19).
+The default value in this file is "core".
+For backward compatibility, if
+.I /proc/sys/kernel/core_pattern
+does not include
+.I %p
+and
+.I /proc/sys/kernel/core_uses_pid
+(see below)
+is nonzero, then .PID will be appended to the core filename.
+.P
+Paths are interpreted according to the settings that are active for the
+crashing process.
+That means the crashing process's mount namespace (see
+.BR mount_namespaces (7)),
+its current working directory (found via
+.BR getcwd (2)),
+and its root directory (see
+.BR chroot (2)).
+.P
+Since Linux 2.4, Linux has also provided
+a more primitive method of controlling
+the name of the core dump file.
+If the
+.I /proc/sys/kernel/core_uses_pid
+file contains the value 0, then a core dump file is simply named
+.IR core .
+If this file contains a nonzero value, then the core dump file includes
+the process ID in a name of the form
+.IR core.PID .
+.P
+Since Linux 3.6,
+.\" 9520628e8ceb69fa9a4aee6b57f22675d9e1b709
+if
+.I /proc/sys/fs/suid_dumpable
+is set to 2 ("suidsafe"), the pattern must be either an absolute pathname
+(starting with a leading \[aq]/\[aq] character) or a pipe, as defined below.
+.SS Piping core dumps to a program
+Since Linux 2.6.19, Linux supports an alternate syntax for the
+.I /proc/sys/kernel/core_pattern
+file.
+If the first character of this file is a pipe symbol (\fB|\fP),
+then the remainder of the line is interpreted as the command-line for
+a user-space program (or script) that is to be executed.
+.P
+Since Linux 5.3.0,
+.\" commit 315c69261dd3fa12dbc830d4fa00d1fad98d3b03
+the pipe template is split on spaces into an argument list
+.I before
+the template parameters are expanded.
+In earlier kernels, the template parameters are expanded first and
+the resulting string is split on spaces into an argument list.
+This means that in earlier kernels executable names added by the
+.I %e
+and
+.I %E
+template parameters could get split into multiple arguments.
+So the core dump handler needs to put the executable names as the last
+argument and ensure it joins all parts of the executable name using spaces.
+Executable names with multiple spaces in them are not correctly represented
+in earlier kernels,
+meaning that the core dump handler needs to use mechanisms to find
+the executable name.
+.P
+Instead of being written to a file, the core dump is given as
+standard input to the program.
+Note the following points:
+.IP \[bu] 3
+The program must be specified using an absolute pathname (or a
+pathname relative to the root directory, \fI/\fP),
+and must immediately follow the '|' character.
+.IP \[bu]
+The command-line arguments can include any of
+the % specifiers listed above.
+For example, to pass the PID of the process that is being dumped, specify
+.I %p
+in an argument.
+.IP \[bu]
+The process created to run the program runs as user and group
+.IR root .
+.IP \[bu]
+Running as
+.I root
+does not confer any exceptional security bypasses.
+Namely, LSMs (e.g., SELinux) are still active and may prevent the handler
+from accessing details about the crashed process via
+.IR /proc/ pid.
+.IP \[bu]
+The program pathname is interpreted with respect to the initial mount namespace
+as it is always executed there.
+It is not affected by the settings
+(e.g., root directory, mount namespace, current working directory)
+of the crashing process.
+.IP \[bu]
+The process runs in the initial namespaces
+(PID, mount, user, and so on)
+and not in the namespaces of the crashing process.
+One can utilize specifiers such as
+.I %P
+to find the right
+.IR /proc/ pid
+directory and probe/enter the crashing process's namespaces if needed.
+.IP \[bu]
+The process starts with its current working directory
+as the root directory.
+If desired, it is possible change to the working directory of
+the dumping process by employing the value provided by the
+.I %P
+specifier to change to the location of the dumping process via
+.IR /proc/ pid /cwd .
+.IP \[bu]
+Command-line arguments can be supplied to the
+program (since Linux 2.6.24),
+delimited by white space (up to a total line length of 128 bytes).
+.IP \[bu]
+The
+.B RLIMIT_CORE
+limit is not enforced for core dumps that are piped to a program
+via this mechanism.
+.\"
+.SS /proc/sys/kernel/core_pipe_limit
+When collecting core dumps via a pipe to a user-space program,
+it can be useful for the collecting program to gather data about
+the crashing process from that process's
+.IR /proc/ pid
+directory.
+In order to do this safely,
+the kernel must wait for the program collecting the core dump to exit,
+so as not to remove the crashing process's
+.IR /proc/ pid
+files prematurely.
+This in turn creates the
+possibility that a misbehaving collecting program can block
+the reaping of a crashed process by simply never exiting.
+.P
+Since Linux 2.6.32,
+.\" commit a293980c2e261bd5b0d2a77340dd04f684caff58
+the
+.I /proc/sys/kernel/core_pipe_limit
+can be used to defend against this possibility.
+The value in this file defines how many concurrent crashing
+processes may be piped to user-space programs in parallel.
+If this value is exceeded, then those crashing processes above this value
+are noted in the kernel log and their core dumps are skipped.
+.P
+A value of 0 in this file is special.
+It indicates that unlimited processes may be captured in parallel,
+but that no waiting will take place (i.e., the collecting
+program is not guaranteed access to
+.IR /proc/<crashing\-PID> ).
+The default value for this file is 0.
+.\"
+.SS Controlling which mappings are written to the core dump
+Since Linux 2.6.23, the Linux-specific
+.IR /proc/ pid /coredump_filter
+file can be used to control which memory segments are written to the
+core dump file in the event that a core dump is performed for the
+process with the corresponding process ID.
+.P
+The value in the file is a bit mask of memory mapping types (see
+.BR mmap (2)).
+If a bit is set in the mask, then memory mappings of the
+corresponding type are dumped; otherwise they are not dumped.
+The bits in this file have the following meanings:
+.P
+.PD 0
+.RS 4
+.TP
+bit 0
+Dump anonymous private mappings.
+.TP
+bit 1
+Dump anonymous shared mappings.
+.TP
+bit 2
+Dump file-backed private mappings.
+.TP
+bit 3
+Dump file-backed shared mappings.
+.\" file-backed shared mappings of course also update the underlying
+.\" mapped file.
+.TP
+bit 4 (since Linux 2.6.24)
+Dump ELF headers.
+.TP
+bit 5 (since Linux 2.6.28)
+Dump private huge pages.
+.TP
+bit 6 (since Linux 2.6.28)
+Dump shared huge pages.
+.TP
+bit 7 (since Linux 4.4)
+.\" commit ab27a8d04b32b6ee8c30c14c4afd1058e8addc82
+Dump private DAX pages.
+.TP
+bit 8 (since Linux 4.4)
+.\" commit ab27a8d04b32b6ee8c30c14c4afd1058e8addc82
+Dump shared DAX pages.
+.RE
+.PD
+.P
+By default, the following bits are set: 0, 1, 4 (if the
+.B CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS
+kernel configuration option is enabled), and 5.
+This default can be modified at boot time using the
+.I coredump_filter
+boot option.
+.P
+The value of this file is displayed in hexadecimal.
+(The default value is thus displayed as 33.)
+.P
+Memory-mapped I/O pages such as frame buffer are never dumped, and
+virtual DSO
+.RB ( vdso (7))
+pages are always dumped, regardless of the
+.I coredump_filter
+value.
+.P
+A child process created via
+.BR fork (2)
+inherits its parent's
+.I coredump_filter
+value;
+the
+.I coredump_filter
+value is preserved across an
+.BR execve (2).
+.P
+It can be useful to set
+.I coredump_filter
+in the parent shell before running a program, for example:
+.P
+.in +4n
+.EX
+.RB "$" " echo 0x7 > /proc/self/coredump_filter"
+.RB "$" " ./some_program"
+.EE
+.in
+.P
+This file is provided only if the kernel was built with the
+.B CONFIG_ELF_CORE
+configuration option.
+.\"
+.SS Core dumps and systemd
+On systems using the
+.BR systemd (1)
+.I init
+framework, core dumps may be placed in a location determined by
+.BR systemd (1).
+To do this,
+.BR systemd (1)
+employs the
+.I core_pattern
+feature that allows piping core dumps to a program.
+One can verify this by checking whether core dumps are being piped to the
+.BR systemd\-coredump (8)
+program:
+.P
+.in +4n
+.EX
+$ \fBcat /proc/sys/kernel/core_pattern\fP
+|/usr/lib/systemd/systemd\-coredump %P %u %g %s %t %c %e
+.EE
+.in
+.P
+In this case, core dumps will be placed in the location configured for
+.BR systemd\-coredump (8),
+typically as
+.BR lz4 (1)
+compressed files in the directory
+.IR /var/lib/systemd/coredump/ .
+One can list the core dumps that have been recorded by
+.BR systemd\-coredump (8)
+using
+.BR coredumpctl (1):
+.P
+.EX
+$ \fBcoredumpctl list | tail \-5\fP
+Wed 2017\-10\-11 22:25:30 CEST  2748 1000 1000 3 present  /usr/bin/sleep
+Thu 2017\-10\-12 06:29:10 CEST  2716 1000 1000 3 present  /usr/bin/sleep
+Thu 2017\-10\-12 06:30:50 CEST  2767 1000 1000 3 present  /usr/bin/sleep
+Thu 2017\-10\-12 06:37:40 CEST  2918 1000 1000 3 present  /usr/bin/cat
+Thu 2017\-10\-12 08:13:07 CEST  2955 1000 1000 3 present  /usr/bin/cat
+.EE
+.P
+The information shown for each core dump includes the date and time
+of the dump, the PID, UID, and GID  of the dumping process,
+the signal number that caused the core dump,
+and the pathname of the executable that was being run by the dumped process.
+Various options to
+.BR coredumpctl (1)
+allow a specified coredump file to be pulled from the
+.BR systemd (1)
+location into a specified file.
+For example, to extract the core dump for PID 2955 shown above to a file named
+.I core
+in the current directory, one could use:
+.P
+.in +4n
+.EX
+$ \fBcoredumpctl dump 2955 \-o core\fP
+.EE
+.in
+.P
+For more extensive details, see the
+.BR coredumpctl (1)
+manual page.
+.P
+To (persistently) disable the
+.BR systemd (1)
+mechanism that archives core dumps, restoring to something more like
+traditional Linux behavior, one can set an override for the
+.BR systemd (1)
+mechanism, using something like:
+.P
+.in +4n
+.EX
+# \fBecho "kernel.core_pattern=core.%p" > \e\fP
+\fB               /etc/sysctl.d/50\-coredump.conf\fP
+# \fB/lib/systemd/systemd\-sysctl\fP
+.EE
+.in
+.P
+It is also possible to temporarily (i.e., until the next reboot) change the
+.I core_pattern
+setting using a command such as the following
+(which causes the names of core dump files to include the executable name
+as well as the number of the signal which triggered the core dump):
+.P
+.in +4n
+.EX
+# \fBsysctl \-w kernel.core_pattern="%e\-%s.core"\fP
+.EE
+.in
+.\"
+.SH NOTES
+The
+.BR gdb (1)
+.I gcore
+command can be used to obtain a core dump of a running process.
+.P
+In Linux versions up to and including 2.6.27,
+.\" Changed with commit 6409324b385f3f63a03645b4422e3be67348d922
+if a multithreaded process (or, more precisely, a process that
+shares its memory with another process by being created with the
+.B CLONE_VM
+flag of
+.BR clone (2))
+dumps core, then the process ID is always appended to the core filename,
+unless the process ID was already included elsewhere in the
+filename via a
+.I %p
+specification in
+.IR /proc/sys/kernel/core_pattern .
+(This is primarily useful when employing the obsolete
+LinuxThreads implementation,
+where each thread of a process has a different PID.)
+.\" Always including the PID in the name of the core file made
+.\" sense for LinuxThreads, where each thread had a unique PID,
+.\" but doesn't seem to serve any purpose with NPTL, where all the
+.\" threads in a process share the same PID (as POSIX.1 requires).
+.\" Probably the behavior is maintained so that applications using
+.\" LinuxThreads continue appending the PID (the kernel has no easy
+.\" way of telling which threading implementation the user-space
+.\" application is using). -- mtk, April 2006
+.SH EXAMPLES
+The program below can be used to demonstrate the use of the
+pipe syntax in the
+.I /proc/sys/kernel/core_pattern
+file.
+The following shell session demonstrates the use of this program
+(compiled to create an executable named
+.IR core_pattern_pipe_test ):
+.P
+.in +4n
+.EX
+.RB "$" " cc \-o core_pattern_pipe_test core_pattern_pipe_test.c"
+.RB "$" " su"
+Password:
+.RB "#" " echo \[dq]|$PWD/core_pattern_pipe_test %p \
+UID=%u GID=%g sig=%s\[dq] > \e"
+.B "    /proc/sys/kernel/core_pattern"
+.RB "#" " exit"
+.RB "$" " sleep 100"
+.BR "\[ha]\e" "                     # type control\-backslash"
+Quit (core dumped)
+.RB "$" " cat core.info"
+argc=5
+argc[0]=</home/mtk/core_pattern_pipe_test>
+argc[1]=<20575>
+argc[2]=<UID=1000>
+argc[3]=<GID=100>
+argc[4]=<sig=3>
+Total bytes in core dump: 282624
+.EE
+.in
+.SS Program source
+\&
+.EX
+/* core_pattern_pipe_test.c */
+\&
+#define _GNU_SOURCE
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+\&
+#define BUF_SIZE 1024
+\&
+int
+main(int argc, char *argv[])
+{
+    ssize_t nread, tot;
+    char buf[BUF_SIZE];
+    FILE *fp;
+    char cwd[PATH_MAX];
+\&
+    /* Change our current working directory to that of the
+       crashing process. */
+\&
+    snprintf(cwd, PATH_MAX, "/proc/%s/cwd", argv[1]);
+    chdir(cwd);
+\&
+    /* Write output to file "core.info" in that directory. */
+\&
+    fp = fopen("core.info", "w+");
+    if (fp == NULL)
+        exit(EXIT_FAILURE);
+\&
+    /* Display command\-line arguments given to core_pattern
+       pipe program. */
+\&
+    fprintf(fp, "argc=%d\en", argc);
+    for (size_t j = 0; j < argc; j++)
+        fprintf(fp, "argc[%zu]=<%s>\en", j, argv[j]);
+\&
+    /* Count bytes in standard input (the core dump). */
+\&
+    tot = 0;
+    while ((nread = read(STDIN_FILENO, buf, BUF_SIZE)) > 0)
+        tot += nread;
+    fprintf(fp, "Total bytes in core dump: %zd\en", tot);
+\&
+    fclose(fp);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR bash (1),
+.BR coredumpctl (1),
+.BR gdb (1),
+.BR getrlimit (2),
+.BR mmap (2),
+.BR prctl (2),
+.BR sigaction (2),
+.BR elf (5),
+.BR proc (5),
+.BR pthreads (7),
+.BR signal (7),
+.BR systemd\-coredump (8)
diff --git a/man/man5/dir_colors.5 b/man/man5/dir_colors.5
new file mode 100644
index 000000000..8115244de
--- /dev/null
+++ b/man/man5/dir_colors.5
@@ -0,0 +1,406 @@
+'\" t
+.\" Copyright (c) 2001 Martin Schulze <joey@infodrom.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH dir_colors 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+dir_colors \- configuration file for dircolors(1)
+.SH DESCRIPTION
+The program
+.BR ls (1)
+uses the environment variable
+.B LS_COLORS
+to determine the colors in which the filenames are to be displayed.
+This environment variable is usually set by a command like
+.P
+.RS
+eval \`dircolors some_path/dir_colors\`
+.RE
+.P
+found in a system default shell initialization file, like
+.I /etc/profile
+or
+.IR /etc/csh.cshrc .
+(See also
+.BR dircolors (1).)
+Usually, the file used here is
+.I /etc/DIR_COLORS
+and can be overridden by a
+.I .dir_colors
+file in one's home directory.
+.P
+This configuration file consists of several statements, one per line.
+Anything right of a hash mark (#) is treated as a comment, if the
+hash mark is at the beginning of a line or is preceded by at least one
+whitespace.
+Blank lines are ignored.
+.P
+The
+.I global
+section of the file consists of any statement before the first
+.B TERM
+statement.
+Any statement in the global section of the file is
+considered valid for all terminal types.
+Following the global section
+is one or more
+.I terminal-specific
+sections, preceded by one or more
+.B TERM
+statements which specify the terminal types (as given by the
+.B TERM
+environment variable) the following declarations apply to.
+It is always possible to override a global declaration by a subsequent
+terminal-specific one.
+.P
+The following statements are recognized; case is insignificant:
+.TP
+.B TERM \fIterminal-type\fR
+Starts a terminal-specific section and specifies which terminal it
+applies to.
+Multiple
+.B TERM
+statements can be used to create a section which applies for several
+terminal types.
+.TP
+.B COLOR yes|all|no|none|tty
+(Slackware only; ignored by GNU
+.BR dircolors (1).)
+Specifies that colorization should always be enabled (\fIyes\fR or
+\fIall\fR), never enabled (\fIno\fR or \fInone\fR), or enabled only if
+the output is a terminal (\fItty\fR).
+The default is \fIno\fR.
+.TP
+.B EIGHTBIT yes|no
+(Slackware only; ignored by GNU
+.BR dircolors (1).)
+Specifies that eight-bit ISO/IEC\~8859 characters should be enabled by
+default.
+For compatibility reasons, this can also be specified as 1 for
+\fIyes\fR or 0 for \fIno\fR.
+The default is \fIno\fR.
+.TP
+.B OPTIONS \fIoptions\fR
+(Slackware only; ignored by GNU
+.BR dircolors (1).)
+Adds command-line options to the default
+.B ls
+command line.
+The options can be any valid
+.B ls
+command-line options, and should include the leading minus sign.
+Note that
+.B dircolors
+does not verify the validity of these options.
+.TP
+.B NORMAL \fIcolor-sequence\fR
+Specifies the color used for normal (nonfilename) text.
+.IP
+Synonym:
+.BR NORM .
+.TP
+.B FILE \fIcolor-sequence\fR
+Specifies the color used for a regular file.
+.TP
+.B DIR \fIcolor-sequence\fR
+Specifies the color used for directories.
+.TP
+.B LINK \fIcolor-sequence\fR
+Specifies the color used for a symbolic link.
+.IP
+Synonyms:
+.BR LNK ,
+.BR SYMLINK .
+.TP
+.B ORPHAN \fIcolor-sequence\fR
+Specifies the color used for an orphaned symbolic link (one which
+points to a nonexistent file).
+If this is unspecified,
+.B ls
+will use the
+.B LINK
+color instead.
+.TP
+.B MISSING \fIcolor-sequence\fR
+Specifies the color used for a missing file (a nonexistent file which
+nevertheless has a symbolic link pointing to it).
+If this is unspecified,
+.B ls
+will use the
+.B FILE
+color instead.
+.TP
+.B FIFO \fIcolor-sequence\fR
+Specifies the color used for a FIFO (named pipe).
+.IP
+Synonym:
+.BR PIPE .
+.TP
+.B SOCK \fIcolor-sequence\fR
+Specifies the color used for a socket.
+.TP
+.B DOOR \fIcolor-sequence\fR
+(Supported since fileutils 4.1)
+Specifies the color used for a door (Solaris 2.5 and later).
+.TP
+.B BLK \fIcolor-sequence\fR
+Specifies the color used for a block device special file.
+.IP
+Synonym:
+.BR BLOCK .
+.TP
+.B CHR \fIcolor-sequence\fR
+Specifies the color used for a character device special file.
+.IP
+Synonym:
+.BR CHAR .
+.TP
+.B EXEC \fIcolor-sequence\fR
+Specifies the color used for a file with the executable attribute set.
+.TP
+.B SUID \fIcolor-sequence\fR
+Specifies the color used for a file with the set-user-ID attribute set.
+.IP
+Synonym:
+.BR SETUID .
+.TP
+.B SGID \fIcolor-sequence\fR
+Specifies the color used for a file with the set-group-ID attribute set.
+.IP
+Synonym:
+.BR SETGID .
+.TP
+.B STICKY \fIcolor-sequence\fR
+Specifies the color used for a directory with the sticky attribute set.
+.TP
+.B STICKY_OTHER_WRITABLE \fIcolor-sequence\fR
+Specifies the color used for
+an other-writable directory with the executable attribute set.
+.IP
+Synonym:
+.BR OWT .
+.TP
+.B OTHER_WRITABLE \fIcolor-sequence\fR
+Specifies the color used for
+an other-writable directory without the executable attribute set.
+.IP
+Synonym:
+.BR OWR .
+.TP
+.B LEFTCODE \fIcolor-sequence\fR
+Specifies the
+.I "left code"
+for non-ISO/IEC\~6429 terminals (see below).
+.IP
+Synonym:
+.BR LEFT .
+.TP
+.B RIGHTCODE \fIcolor-sequence\fR
+Specifies the
+.I "right code"
+for non-ISO/IEC\~6429 terminals (see below).
+.IP
+Synonym:
+.BR RIGHT .
+.TP
+.B ENDCODE \fIcolor-sequence\fR
+Specifies the
+.I "end code"
+for non-ISO/IEC\~6429 terminals (see below).
+.IP
+Synonym:
+.BR END .
+.TP
+.BI * "extension color-sequence"
+Specifies the color used for any file that ends in \fIextension\fR.
+.TP
+.BI . "extension color-sequence"
+Same as \fB*\fR.\fIextension\fR.
+Specifies the color used for any file that
+ends in .\fIextension\fR.
+Note that the period is included in the
+extension, which makes it impossible to specify an extension not
+starting with a period, such as
+.B \[ti]
+for
+.B emacs
+backup files.
+This form should be considered obsolete.
+.SS ISO/IEC\~6429 (ANSI) color sequences
+Most color-capable ASCII terminals today use ISO/IEC\~6429 (ANSI) color sequences,
+and many common terminals without color capability, including
+.B xterm
+and the widely used and cloned DEC VT100, will recognize ISO/IEC\~6429 color
+codes and harmlessly eliminate them from the output or emulate them.
+.B ls
+uses ISO/IEC\~6429 codes by default, assuming colorization is enabled.
+.P
+ISO/IEC\~6429 color sequences are composed of sequences of numbers
+separated by semicolons.
+The most common codes are:
+.RS
+.TS
+l l.
+ 0	to restore default color
+ 1	for brighter colors
+ 4	for underlined text
+ 5	for flashing text
+30	for black foreground
+31	for red foreground
+32	for green foreground
+33	for yellow (or brown) foreground
+34	for blue foreground
+35	for purple foreground
+36	for cyan foreground
+37	for white (or gray) foreground
+40	for black background
+41	for red background
+42	for green background
+43	for yellow (or brown) background
+44	for blue background
+45	for purple background
+46	for cyan background
+47	for white (or gray) background
+.TE
+.RE
+.P
+Not all commands will work on all systems or display devices.
+.P
+.B ls
+uses the following defaults:
+.TS
+lb l l.
+NORMAL	0       	Normal (nonfilename) text
+FILE	0       	Regular file
+DIR	32      	Directory
+LINK	36      	Symbolic link
+ORPHAN	undefined	Orphaned symbolic link
+MISSING	undefined	Missing file
+FIFO	31      	Named pipe (FIFO)
+SOCK	33      	Socket
+BLK	44;37   	Block device
+CHR	44;37   	Character device
+EXEC	35      	Executable file
+.TE
+.P
+A few terminal programs do not recognize the default
+properly.
+If all text gets colorized after you do a directory
+listing, change the
+.B NORMAL
+and
+.B FILE
+codes to the numerical codes for your normal foreground and background
+colors.
+.SS Other terminal types (advanced configuration)
+If you have a color-capable (or otherwise highlighting) terminal (or
+printer!) which uses a different set of codes, you can still generate
+a suitable setup.
+To do so, you will have to use the
+.BR LEFTCODE ,
+.BR RIGHTCODE ,
+and
+.B ENDCODE
+definitions.
+.P
+When writing out a filename,
+.B ls
+generates the following output sequence:
+.B LEFTCODE
+.I typecode
+.B RIGHTCODE
+.I filename
+.BR ENDCODE ,
+where the
+.I typecode
+is the color sequence that depends on the type or name of file.
+If the
+.B ENDCODE
+is undefined, the sequence
+.B "LEFTCODE NORMAL RIGHTCODE"
+will be used instead.
+The purpose of the left- and rightcodes is
+merely to reduce the amount of typing necessary (and to hide ugly
+escape codes away from the user).
+If they are not appropriate for
+your terminal, you can eliminate them by specifying the respective
+keyword on a line by itself.
+.P
+.B NOTE:
+If the
+.B ENDCODE
+is defined in the global section of the setup file, it
+.I cannot
+be undefined in a terminal-specific section of the file.
+This means any
+.B NORMAL
+definition will have no effect.
+A different
+.B ENDCODE
+can, however, be specified, which would have the same effect.
+.SS Escape sequences
+To specify control- or blank characters in the color sequences or
+filename extensions, either C-style \e-escaped notation or
+.BR stty \-style
+\[ha]-notation can be used.
+The C-style notation
+includes the following characters:
+.RS
+.TS
+lb l.
+\ea	Bell (ASCII 7)
+\eb	Backspace (ASCII 8)
+\ee	Escape (ASCII 27)
+\ef	Form feed (ASCII 12)
+\en	Newline (ASCII 10)
+\er	Carriage Return (ASCII 13)
+\et	Tab (ASCII 9)
+\ev	Vertical Tab (ASCII 11)
+\e?	Delete (ASCII 127)
+\e\fInnn	Any character (octal notation)
+\ex\fInnn	Any character (hexadecimal notation)
+\e_	Space
+\e\e	Backslash (\e)
+\e\[ha]	Caret (\[ha])
+\e#	Hash mark (#)
+.TE
+.RE
+.P
+Note that escapes are necessary to enter a space, backslash,
+caret, or any control character anywhere in the string, as well as a
+hash mark as the first character.
+.SH FILES
+.TP
+.I /etc/DIR_COLORS
+System-wide configuration file.
+.TP
+.I \[ti]/.dir_colors
+Per-user configuration file.
+.P
+This page describes the
+.B dir_colors
+file format as used in the fileutils-4.1 package;
+other versions may differ slightly.
+.SH NOTES
+The default
+.B LEFTCODE
+and
+.B RIGHTCODE
+definitions, which are used by ISO/IEC\~6429 terminals are:
+.RS
+.TS
+lb l.
+LEFTCODE	\ee[
+RIGHTCODE	m
+.TE
+.RE
+.P
+The default
+.B ENDCODE
+is undefined.
+.SH SEE ALSO
+.BR dircolors (1),
+.BR ls (1),
+.BR stty (1),
+.BR xterm (1)
diff --git a/man/man5/elf.5 b/man/man5/elf.5
new file mode 100644
index 000000000..9aff88afb
--- /dev/null
+++ b/man/man5/elf.5
@@ -0,0 +1,2213 @@
+.\"	$OpenBSD: elf.5,v 1.12 2003/10/27 20:23:58 jmc Exp $
+.\"Copyright (c) 1999 Jeroen Ruigrok van der Werven
+.\"All rights reserved.
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\"Redistribution and use in source and binary forms, with or without
+.\"modification, are permitted provided that the following conditions
+.\"are met:
+.\"1. Redistributions of source code must retain the above copyright
+.\"   notice, this list of conditions and the following disclaimer.
+.\"2. Redistributions in binary form must reproduce the above copyright
+.\"   notice, this list of conditions and the following disclaimer in the
+.\"   documentation and/or other materials provided with the distribution.
+.\"
+.\"THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\"ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\"IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\"ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\"FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\"DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\"OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\"HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\"LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\"OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\"SUCH DAMAGE.
+.\" %%%LICENSE_END
+.\"
+.\"	$FreeBSD: src/share/man/man5/elf.5,v 1.21 2001/10/01 16:09:23 ru Exp $
+.\"
+.\" Slightly adapted - aeb, 2004-01-01
+.\" 2005-07-15, Mike Frysinger <vapier@gentoo.org>, various fixes
+.\" 2007-10-11, Mike Frysinger <vapier@gentoo.org>, various fixes
+.\" 2007-12-08, mtk, Converted from mdoc to man macros
+.\"
+.TH ELF 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+elf \- format of Executable and Linking Format (ELF) files
+.SH SYNOPSIS
+.nf
+.\" .B #include <elf_abi.h>
+.B #include <elf.h>
+.fi
+.SH DESCRIPTION
+The header file
+.I <elf.h>
+defines the format of ELF executable binary files.
+Amongst these files are
+normal executable files, relocatable object files, core files, and shared
+objects.
+.P
+An executable file using the ELF file format consists of an ELF header,
+followed by a program header table or a section header table, or both.
+The ELF header is always at offset zero of the file.
+The program header
+table and the section header table's offset in the file are defined in the
+ELF header.
+The two tables describe the rest of the particularities of
+the file.
+.P
+.\" Applications which wish to process ELF binary files for their native
+.\" architecture only should include
+.\" .I <elf_abi.h>
+.\" in their source code.
+.\" These applications should need to refer to
+.\" all the types and structures by their generic names
+.\" "Elf_xxx"
+.\" and to the macros by
+.\" ELF_xxx".
+.\" Applications written this way can be compiled on any architecture,
+.\" regardless of whether the host is 32-bit or 64-bit.
+.\" .P
+.\" Should an application need to process ELF files of an unknown
+.\" architecture, then the application needs to explicitly use either
+.\" "Elf32_xxx"
+.\" or
+.\" "Elf64_xxx"
+.\" type and structure names.
+.\" Likewise, the macros need to be identified by
+.\" "ELF32_xxx"
+.\" or
+.\" "ELF64_xxx".
+.\" .P
+This header file describes the above mentioned headers as C structures
+and also includes structures for dynamic sections, relocation sections and
+symbol tables.
+.\"
+.SS Basic types
+The following types are used for N-bit architectures (N=32,64,
+.I ElfN
+stands for
+.I Elf32
+or
+.IR Elf64 ,
+.I uintN_t
+stands for
+.I uint32_t
+or
+.IR uint64_t ):
+.P
+.in +4n
+.EX
+ElfN_Addr       Unsigned program address, uintN_t
+ElfN_Off        Unsigned file offset, uintN_t
+ElfN_Section    Unsigned section index, uint16_t
+ElfN_Versym     Unsigned version symbol information, uint16_t
+Elf_Byte        unsigned char
+ElfN_Half       uint16_t
+ElfN_Sword      int32_t
+ElfN_Word       uint32_t
+ElfN_Sxword     int64_t
+ElfN_Xword      uint64_t
+.\" Elf32_Size  Unsigned object size
+.EE
+.in
+.P
+(Note: the *BSD terminology is a bit different.
+There,
+.I Elf64_Half
+is
+twice as large as
+.IR Elf32_Half ,
+and
+.I Elf64Quarter
+is used for
+.IR uint16_t .
+In order to avoid confusion these types are replaced by explicit ones
+in the below.)
+.P
+All data structures that the file format defines follow the
+"natural"
+size and alignment guidelines for the relevant class.
+If necessary,
+data structures contain explicit padding to ensure 4-byte alignment
+for 4-byte objects, to force structure sizes to a multiple of 4, and so on.
+.\"
+.SS ELF header (Ehdr)
+The ELF header is described by the type
+.I Elf32_Ehdr
+or
+.IR Elf64_Ehdr :
+.P
+.in +4n
+.EX
+#define EI_NIDENT 16
+\&
+typedef struct {
+    unsigned char e_ident[EI_NIDENT];
+    uint16_t      e_type;
+    uint16_t      e_machine;
+    uint32_t      e_version;
+    ElfN_Addr     e_entry;
+    ElfN_Off      e_phoff;
+    ElfN_Off      e_shoff;
+    uint32_t      e_flags;
+    uint16_t      e_ehsize;
+    uint16_t      e_phentsize;
+    uint16_t      e_phnum;
+    uint16_t      e_shentsize;
+    uint16_t      e_shnum;
+    uint16_t      e_shstrndx;
+} ElfN_Ehdr;
+.EE
+.in
+.P
+The fields have the following meanings:
+.\"
+.\"
+.TP
+.I e_ident
+This array of bytes specifies how to interpret the file,
+independent of the processor or the file's remaining contents.
+Within this array everything is named by macros, which start with
+the prefix
+.B EI_
+and may contain values which start with the prefix
+.BR ELF .
+The following macros are defined:
+.RS
+.TP
+.B EI_MAG0
+The first byte of the magic number.
+It must be filled with
+.BR ELFMAG0 .
+(0: 0x7f)
+.TP
+.B EI_MAG1
+The second byte of the magic number.
+It must be filled with
+.BR ELFMAG1 .
+(1: \[aq]E\[aq])
+.TP
+.B EI_MAG2
+The third byte of the magic number.
+It must be filled with
+.BR ELFMAG2 .
+(2: \[aq]L\[aq])
+.TP
+.B EI_MAG3
+The fourth byte of the magic number.
+It must be filled with
+.BR ELFMAG3 .
+(3: \[aq]F\[aq])
+.TP
+.B EI_CLASS
+The fifth byte identifies the architecture for this binary:
+.RS
+.TP 14
+.PD 0
+.B ELFCLASSNONE
+This class is invalid.
+.TP
+.B ELFCLASS32
+This defines the 32-bit architecture.
+It supports machines with files
+and virtual address spaces up to 4 Gigabytes.
+.TP
+.B ELFCLASS64
+This defines the 64-bit architecture.
+.PD
+.RE
+.TP
+.B EI_DATA
+The sixth byte specifies the data encoding of the processor-specific
+data in the file.
+Currently, these encodings are supported:
+.RS 9
+.TP 14
+.PD 0
+.B ELFDATANONE
+Unknown data format.
+.TP
+.B ELFDATA2LSB
+Two's complement, little-endian.
+.TP
+.B ELFDATA2MSB
+Two's complement, big-endian.
+.PD
+.RE
+.TP
+.B EI_VERSION
+The seventh byte is the version number of the ELF specification:
+.IP
+.PD 0
+.RS
+.TP 14
+.B EV_NONE
+Invalid version.
+.TP
+.B EV_CURRENT
+Current version.
+.PD
+.RE
+.\".El
+.TP
+.B EI_OSABI
+The eighth byte identifies the operating system
+and ABI to which the object is targeted.
+Some fields in other ELF structures have flags
+and values that have platform-specific meanings;
+the interpretation of those fields is determined by the value of this byte.
+For example:
+.RS
+.TP 21
+.PD 0
+.B ELFOSABI_NONE
+Same as ELFOSABI_SYSV
+.\" 0
+.TP
+.B ELFOSABI_SYSV
+UNIX System V ABI
+.\" 0
+.\" synonym: ELFOSABI_NONE
+.TP
+.B ELFOSABI_HPUX
+HP-UX ABI
+.\" 1
+.TP
+.B ELFOSABI_NETBSD
+NetBSD ABI
+.\" 2
+.TP
+.B ELFOSABI_LINUX
+Linux ABI
+.\" 3
+.\" .TP
+.\" .BR ELFOSABI_HURD
+.\" Hurd ABI
+.\" 4
+.\" .TP
+.\" .BR ELFOSABI_86OPEN
+.\" 86Open Common IA32 ABI
+.\" 5
+.TP
+.B ELFOSABI_SOLARIS
+Solaris ABI
+.\" 6
+.\" .TP
+.\" .BR ELFOSABI_MONTEREY
+.\" Monterey project ABI
+.\" Now replaced by
+.\" ELFOSABI_AIX
+.\" 7
+.TP
+.B ELFOSABI_IRIX
+IRIX ABI
+.\" 8
+.TP
+.B ELFOSABI_FREEBSD
+FreeBSD ABI
+.\" 9
+.TP
+.B ELFOSABI_TRU64
+TRU64 UNIX ABI
+.\" 10
+.\" ELFOSABI_MODESTO
+.\" 11
+.\" ELFOSABI_OPENBSD
+.\" 12
+.TP
+.B ELFOSABI_ARM
+ARM architecture ABI
+.\" 97
+.TP
+.B ELFOSABI_STANDALONE
+Stand-alone (embedded) ABI
+.\" 255
+.PD
+.RE
+.TP
+.B EI_ABIVERSION
+The ninth byte identifies the version of the ABI
+to which the object is targeted.
+This field is used to distinguish among incompatible versions of an ABI.
+The interpretation of this version number
+is dependent on the ABI identified by the
+.B EI_OSABI
+field.
+Applications conforming to this specification use the value 0.
+.TP
+.B EI_PAD
+Start of padding.
+These bytes are reserved and set to zero.
+Programs
+which read them should ignore them.
+The value for
+.B EI_PAD
+will change in
+the future if currently unused bytes are given meanings.
+.\" As reported by Yuri Kozlov and confirmed by Mike Frysinger, EI_BRAND is
+.\" not in GABI (http://www.sco.com/developers/gabi/latest/ch4.eheader.html)
+.\" It looks to be a BSDism
+.\" .TP
+.\" .BR EI_BRAND
+.\" Start of architecture identification.
+.TP
+.B EI_NIDENT
+The size of the
+.I e_ident
+array.
+.RE
+.TP
+.I e_type
+This member of the structure identifies the object file type:
+.RS
+.TP 16
+.PD 0
+.B ET_NONE
+An unknown type.
+.TP
+.B ET_REL
+A relocatable file.
+.TP
+.B ET_EXEC
+An executable file.
+.TP
+.B ET_DYN
+A shared object.
+.TP
+.B ET_CORE
+A core file.
+.PD
+.RE
+.TP
+.I e_machine
+This member specifies the required architecture for an individual file.
+For example:
+.RS
+.TP 16
+.PD 0
+.B EM_NONE
+An unknown machine
+.\" 0
+.TP
+.B EM_M32
+AT&T WE 32100
+.\" 1
+.TP
+.B EM_SPARC
+Sun Microsystems SPARC
+.\" 2
+.TP
+.B EM_386
+Intel 80386
+.\" 3
+.TP
+.B EM_68K
+Motorola 68000
+.\" 4
+.TP
+.B EM_88K
+Motorola 88000
+.\" 5
+.\" .TP
+.\" .BR EM_486
+.\" Intel 80486
+.\" 6
+.TP
+.B EM_860
+Intel 80860
+.\" 7
+.TP
+.B EM_MIPS
+MIPS RS3000 (big-endian only)
+.\" 8
+.\" EM_S370
+.\" 9
+.\" .TP
+.\" .BR EM_MIPS_RS4_BE
+.\" MIPS RS4000 (big-endian only). Deprecated
+.\" 10
+.\" EM_MIPS_RS3_LE (MIPS R3000 little-endian)
+.\" 10
+.TP
+.B EM_PARISC
+HP/PA
+.\" 15
+.TP
+.B EM_SPARC32PLUS
+SPARC with enhanced instruction set
+.\" 18
+.TP
+.B EM_PPC
+PowerPC
+.\" 20
+.TP
+.B EM_PPC64
+PowerPC 64-bit
+.\" 21
+.TP
+.B EM_S390
+IBM S/390
+.\" 22
+.TP
+.B EM_ARM
+Advanced RISC Machines
+.\" 40
+.TP
+.B EM_SH
+Renesas SuperH
+.\" 42
+.TP
+.B EM_SPARCV9
+SPARC v9 64-bit
+.\" 43
+.TP
+.B EM_IA_64
+Intel Itanium
+.\" 50
+.TP
+.B EM_X86_64
+AMD x86-64
+.\" 62
+.TP
+.B EM_VAX
+DEC Vax
+.\" 75
+.\" EM_CRIS
+.\" 76
+.\" .TP
+.\" .BR EM_ALPHA
+.\" Compaq [DEC] Alpha
+.\" .TP
+.\" .BR EM_ALPHA_EXP
+.\" Compaq [DEC] Alpha with enhanced instruction set
+.PD
+.RE
+.TP
+.I e_version
+This member identifies the file version:
+.RS
+.TP 16
+.PD 0
+.B EV_NONE
+Invalid version
+.TP
+.B EV_CURRENT
+Current version
+.PD
+.RE
+.TP
+.I e_entry
+This member gives the virtual address to which the system first transfers
+control, thus starting the process.
+If the file has no associated entry
+point, this member holds zero.
+.TP
+.I e_phoff
+This member holds the program header table's file offset in bytes.
+If
+the file has no program header table, this member holds zero.
+.TP
+.I e_shoff
+This member holds the section header table's file offset in bytes.
+If the
+file has no section header table, this member holds zero.
+.TP
+.I e_flags
+This member holds processor-specific flags associated with the file.
+Flag names take the form EF_`machine_flag'.
+Currently, no flags have been defined.
+.TP
+.I e_ehsize
+This member holds the ELF header's size in bytes.
+.TP
+.I e_phentsize
+This member holds the size in bytes of one entry in the file's
+program header table; all entries are the same size.
+.TP
+.I e_phnum
+This member holds the number of entries in the program header
+table.
+Thus the product of
+.I e_phentsize
+and
+.I e_phnum
+gives the table's size
+in bytes.
+If a file has no program header,
+.I e_phnum
+holds the value zero.
+.IP
+If the number of entries in the program header table is
+larger than or equal to
+.\" This is a Linux extension, added in Linux 2.6.34.
+.B PN_XNUM
+(0xffff), this member holds
+.B PN_XNUM
+(0xffff) and the real number of entries in the program header table is held
+in the
+.I sh_info
+member of the initial entry in section header table.
+Otherwise, the
+.I sh_info
+member of the initial entry contains the value zero.
+.RS
+.TP
+.B PN_XNUM
+This is defined as 0xffff, the largest number
+.I e_phnum
+can have, specifying where the actual number of program headers is assigned.
+.PD
+.RE
+.TP
+.I e_shentsize
+This member holds a sections header's size in bytes.
+A section header is one
+entry in the section header table; all entries are the same size.
+.TP
+.I e_shnum
+This member holds the number of entries in the section header table.
+Thus
+the product of
+.I e_shentsize
+and
+.I e_shnum
+gives the section header table's size in bytes.
+If a file has no section
+header table,
+.I e_shnum
+holds the value of zero.
+.IP
+If the number of entries in the section header table is
+larger than or equal to
+.B SHN_LORESERVE
+(0xff00),
+.I e_shnum
+holds the value zero and the real number of entries in the section header
+table is held in the
+.I sh_size
+member of the initial entry in section header table.
+Otherwise, the
+.I sh_size
+member of the initial entry in the section header table holds
+the value zero.
+.TP
+.I e_shstrndx
+This member holds the section header table index of the entry associated
+with the section name string table.
+If the file has no section name string
+table, this member holds the value
+.BR SHN_UNDEF .
+.IP
+If the index of section name string table section is
+larger than or equal to
+.B SHN_LORESERVE
+(0xff00), this member holds
+.B SHN_XINDEX
+(0xffff) and the real index of the section name string table section
+is held in the
+.I sh_link
+member of the initial entry in section header table.
+Otherwise, the
+.I sh_link
+member of the initial entry in section header table contains the value zero.
+.\"
+.SS Program header (Phdr)
+An executable or shared object file's program header table is an array of
+structures, each describing a segment or other information the system needs
+to prepare the program for execution.
+An object file
+.I segment
+contains one or more
+.IR sections .
+Program headers are meaningful only for executable and shared object files.
+A file specifies its own program header size with the ELF header's
+.I e_phentsize
+and
+.I e_phnum
+members.
+The ELF program header is described by the type
+.I Elf32_Phdr
+or
+.I Elf64_Phdr
+depending on the architecture:
+.P
+.in +4n
+.EX
+typedef struct {
+    uint32_t   p_type;
+    Elf32_Off  p_offset;
+    Elf32_Addr p_vaddr;
+    Elf32_Addr p_paddr;
+    uint32_t   p_filesz;
+    uint32_t   p_memsz;
+    uint32_t   p_flags;
+    uint32_t   p_align;
+} Elf32_Phdr;
+.EE
+.in
+.P
+.in +4n
+.EX
+typedef struct {
+    uint32_t   p_type;
+    uint32_t   p_flags;
+    Elf64_Off  p_offset;
+    Elf64_Addr p_vaddr;
+    Elf64_Addr p_paddr;
+    uint64_t   p_filesz;
+    uint64_t   p_memsz;
+    uint64_t   p_align;
+} Elf64_Phdr;
+.EE
+.in
+.P
+The main difference between the 32-bit and the 64-bit program header lies
+in the location of the
+.I p_flags
+member in the total struct.
+.TP
+.I p_type
+This member of the structure indicates what kind of segment this array
+element describes or how to interpret the array element's information.
+.RS 10
+.TP
+.B PT_NULL
+The array element is unused and the other members' values are undefined.
+This lets the program header have ignored entries.
+.TP
+.B PT_LOAD
+The array element specifies a loadable segment, described by
+.I p_filesz
+and
+.IR p_memsz .
+The bytes from the file are mapped to the beginning of the memory
+segment.
+If the segment's memory size
+.I p_memsz
+is larger than the file size
+.IR p_filesz ,
+the
+"extra"
+bytes are defined to hold the value 0 and to follow the segment's
+initialized area.
+The file size may not be larger than the memory size.
+Loadable segment entries in the program header table appear in ascending
+order, sorted on the
+.I p_vaddr
+member.
+.TP
+.B PT_DYNAMIC
+The array element specifies dynamic linking information.
+.TP
+.B PT_INTERP
+The array element specifies the location and size of a null-terminated
+pathname to invoke as an interpreter.
+This segment type is meaningful
+only for executable files (though it may occur for shared objects).
+However it may not occur more than once in a file.
+If it is present, it must precede any loadable segment entry.
+.TP
+.B PT_NOTE
+The array element specifies the location of notes (ElfN_Nhdr).
+.TP
+.B PT_SHLIB
+This segment type is reserved but has unspecified semantics.
+Programs that
+contain an array element of this type do not conform to the ABI.
+.TP
+.B PT_PHDR
+The array element, if present,
+specifies the location and size of the program header table itself,
+both in the file and in the memory image of the program.
+This segment type may not occur more than once in a file.
+Moreover, it may
+occur only if the program header table is part of the memory image of the
+program.
+If it is present, it must precede any loadable segment entry.
+.TP
+.B PT_LOPROC
+.TQ
+.B PT_HIPROC
+Values in the inclusive range
+.RB [ PT_LOPROC ,
+.BR PT_HIPROC ]
+are reserved for processor-specific semantics.
+.TP
+.B PT_GNU_STACK
+GNU extension which is used by the Linux kernel to control the state of the
+stack via the flags set in the
+.I p_flags
+member.
+.RE
+.TP
+.I p_offset
+This member holds the offset from the beginning of the file at which
+the first byte of the segment resides.
+.TP
+.I p_vaddr
+This member holds the virtual address at which the first byte of the
+segment resides in memory.
+.TP
+.I p_paddr
+On systems for which physical addressing is relevant, this member is
+reserved for the segment's physical address.
+Under
+BSD
+this member is
+not used and must be zero.
+.TP
+.I p_filesz
+This member holds the number of bytes in the file image of the segment.
+It may be zero.
+.TP
+.I p_memsz
+This member holds the number of bytes in the memory image of the segment.
+It may be zero.
+.TP
+.I p_flags
+This member holds a bit mask of flags relevant to the segment:
+.RS
+.TP
+.PD 0
+.B PF_X
+An executable segment.
+.TP
+.B PF_W
+A writable segment.
+.TP
+.B PF_R
+A readable segment.
+.PD
+.RE
+.IP
+A text segment commonly has the flags
+.B PF_X
+and
+.BR PF_R .
+A data segment commonly has
+.B PF_W
+and
+.BR PF_R .
+.TP
+.I p_align
+This member holds the value to which the segments are aligned in memory
+and in the file.
+Loadable process segments must have congruent values for
+.I p_vaddr
+and
+.IR p_offset ,
+modulo the page size.
+Values of zero and one mean no alignment is required.
+Otherwise,
+.I p_align
+should be a positive, integral power of two, and
+.I p_vaddr
+should equal
+.IR p_offset ,
+modulo
+.IR p_align .
+.\"
+.SS Section header (Shdr)
+A file's section header table lets one locate all the file's sections.
+The
+section header table is an array of
+.I Elf32_Shdr
+or
+.I Elf64_Shdr
+structures.
+The
+ELF header's
+.I e_shoff
+member gives the byte offset from the beginning of the file to the section
+header table.
+.I e_shnum
+holds the number of entries the section header table contains.
+.I e_shentsize
+holds the size in bytes of each entry.
+.P
+A section header table index is a subscript into this array.
+Some section
+header table indices are reserved:
+the initial entry and the indices between
+.B SHN_LORESERVE
+and
+.BR SHN_HIRESERVE .
+The initial entry is used in ELF extensions for
+.IR e_phnum ,
+.IR e_shnum ,
+and
+.IR e_shstrndx ;
+in other cases, each field in the initial entry is set to zero.
+An object file does not have sections for
+these special indices:
+.TP
+.B SHN_UNDEF
+This value marks an undefined, missing, irrelevant,
+or otherwise meaningless section reference.
+.TP
+.B SHN_LORESERVE
+This value specifies the lower bound of the range of reserved indices.
+.TP
+.B SHN_LOPROC
+.TQ
+.B SHN_HIPROC
+Values greater in the inclusive range
+.RB [ SHN_LOPROC ,
+.BR SHN_HIPROC ]
+are reserved for processor-specific semantics.
+.TP
+.B SHN_ABS
+This value specifies the absolute value for the corresponding reference.
+For
+example, a symbol defined relative to section number
+.B SHN_ABS
+has an absolute value and is not affected by relocation.
+.TP
+.B SHN_COMMON
+Symbols defined relative to this section are common symbols,
+such as FORTRAN COMMON or unallocated C external variables.
+.TP
+.B SHN_HIRESERVE
+This value specifies the upper bound of the range of reserved indices.
+The
+system reserves indices between
+.B SHN_LORESERVE
+and
+.BR SHN_HIRESERVE ,
+inclusive.
+The section header table does not contain entries for the
+reserved indices.
+.P
+The section header has the following structure:
+.P
+.in +4n
+.EX
+typedef struct {
+    uint32_t   sh_name;
+    uint32_t   sh_type;
+    uint32_t   sh_flags;
+    Elf32_Addr sh_addr;
+    Elf32_Off  sh_offset;
+    uint32_t   sh_size;
+    uint32_t   sh_link;
+    uint32_t   sh_info;
+    uint32_t   sh_addralign;
+    uint32_t   sh_entsize;
+} Elf32_Shdr;
+.EE
+.in
+.P
+.in +4n
+.EX
+typedef struct {
+    uint32_t   sh_name;
+    uint32_t   sh_type;
+    uint64_t   sh_flags;
+    Elf64_Addr sh_addr;
+    Elf64_Off  sh_offset;
+    uint64_t   sh_size;
+    uint32_t   sh_link;
+    uint32_t   sh_info;
+    uint64_t   sh_addralign;
+    uint64_t   sh_entsize;
+} Elf64_Shdr;
+.EE
+.in
+.P
+No real differences exist between the 32-bit and 64-bit section headers.
+.TP
+.I sh_name
+This member specifies the name of the section.
+Its value is an index
+into the section header string table section, giving the location of
+a null-terminated string.
+.TP
+.I sh_type
+This member categorizes the section's contents and semantics.
+.RS
+.TP
+.B SHT_NULL
+This value marks the section header as inactive.
+It does not
+have an associated section.
+Other members of the section header
+have undefined values.
+.TP
+.B SHT_PROGBITS
+This section holds information defined by the program, whose
+format and meaning are determined solely by the program.
+.TP
+.B SHT_SYMTAB
+This section holds a symbol table.
+Typically,
+.B SHT_SYMTAB
+provides symbols for link editing, though it may also be used
+for dynamic linking.
+As a complete symbol table, it may contain
+many symbols unnecessary for dynamic linking.
+An object file can
+also contain a
+.B SHT_DYNSYM
+section.
+.TP
+.B SHT_STRTAB
+This section holds a string table.
+An object file may have multiple
+string table sections.
+.TP
+.B SHT_RELA
+This section holds relocation entries with explicit addends, such
+as type
+.I Elf32_Rela
+for the 32-bit class of object files.
+An object may have multiple
+relocation sections.
+.TP
+.B SHT_HASH
+This section holds a symbol hash table.
+An object participating in
+dynamic linking must contain a symbol hash table.
+An object file may
+have only one hash table.
+.TP
+.B SHT_DYNAMIC
+This section holds information for dynamic linking.
+An object file may
+have only one dynamic section.
+.TP
+.B SHT_NOTE
+This section holds notes (ElfN_Nhdr).
+.TP
+.B SHT_NOBITS
+A section of this type occupies no space in the file but otherwise
+resembles
+.BR SHT_PROGBITS .
+Although this section contains no bytes, the
+.I sh_offset
+member contains the conceptual file offset.
+.TP
+.B SHT_REL
+This section holds relocation offsets without explicit addends, such
+as type
+.I Elf32_Rel
+for the 32-bit class of object files.
+An object file may have multiple
+relocation sections.
+.TP
+.B SHT_SHLIB
+This section is reserved but has unspecified semantics.
+.TP
+.B SHT_DYNSYM
+This section holds a minimal set of dynamic linking symbols.
+An
+object file can also contain a
+.B SHT_SYMTAB
+section.
+.TP
+.B SHT_LOPROC
+.TQ
+.B SHT_HIPROC
+Values in the inclusive range
+.RB [ SHT_LOPROC ,
+.BR SHT_HIPROC ]
+are reserved for processor-specific semantics.
+.TP
+.B SHT_LOUSER
+This value specifies the lower bound of the range of indices reserved for
+application programs.
+.TP
+.B SHT_HIUSER
+This value specifies the upper bound of the range of indices reserved for
+application programs.
+Section types between
+.B SHT_LOUSER
+and
+.B SHT_HIUSER
+may be used by the application, without conflicting with current or future
+system-defined section types.
+.RE
+.TP
+.I sh_flags
+Sections support one-bit flags that describe miscellaneous attributes.
+If a flag bit is set in
+.IR sh_flags ,
+the attribute is
+"on"
+for the section.
+Otherwise, the attribute is
+"off"
+or does not apply.
+Undefined attributes are set to zero.
+.RS
+.TP
+.B SHF_WRITE
+This section contains data that should be writable during process
+execution.
+.TP
+.B SHF_ALLOC
+This section occupies memory during process execution.
+Some control
+sections do not reside in the memory image of an object file.
+This
+attribute is off for those sections.
+.TP
+.B SHF_EXECINSTR
+This section contains executable machine instructions.
+.TP
+.B SHF_MASKPROC
+All bits included in this mask are reserved for processor-specific
+semantics.
+.RE
+.TP
+.I sh_addr
+If this section appears in the memory image of a process, this member
+holds the address at which the section's first byte should reside.
+Otherwise, the member contains zero.
+.TP
+.I sh_offset
+This member's value holds the byte offset from the beginning of the file
+to the first byte in the section.
+One section type,
+.BR SHT_NOBITS ,
+occupies no space in the file, and its
+.I sh_offset
+member locates the conceptual placement in the file.
+.TP
+.I sh_size
+This member holds the section's size in bytes.
+Unless the section type
+is
+.BR SHT_NOBITS ,
+the section occupies
+.I sh_size
+bytes in the file.
+A section of type
+.B SHT_NOBITS
+may have a nonzero size, but it occupies no space in the file.
+.TP
+.I sh_link
+This member holds a section header table index link, whose interpretation
+depends on the section type.
+.TP
+.I sh_info
+This member holds extra information, whose interpretation depends on the
+section type.
+.TP
+.I sh_addralign
+Some sections have address alignment constraints.
+If a section holds a
+doubleword, the system must ensure doubleword alignment for the entire
+section.
+That is, the value of
+.I sh_addr
+must be congruent to zero, modulo the value of
+.IR sh_addralign .
+Only zero and positive integral powers of two are allowed.
+The value 0 or 1 means that the section has no alignment constraints.
+.TP
+.I sh_entsize
+Some sections hold a table of fixed-sized entries, such as a symbol table.
+For such a section, this member gives the size in bytes for each entry.
+This member contains zero if the section does not hold a table of
+fixed-size entries.
+.P
+Various sections hold program and control information:
+.TP
+.I .bss
+This section holds uninitialized data that contributes to the program's
+memory image.
+By definition, the system initializes the data with zeros
+when the program begins to run.
+This section is of type
+.BR SHT_NOBITS .
+The attribute types are
+.B SHF_ALLOC
+and
+.BR SHF_WRITE .
+.TP
+.I .comment
+This section holds version control information.
+This section is of type
+.BR SHT_PROGBITS .
+No attribute types are used.
+.TP
+.I .ctors
+This section holds initialized pointers to the C++ constructor functions.
+This section is of type
+.BR SHT_PROGBITS .
+The attribute types are
+.B SHF_ALLOC
+and
+.BR SHF_WRITE .
+.TP
+.I .data
+This section holds initialized data that contribute to the program's
+memory image.
+This section is of type
+.BR SHT_PROGBITS .
+The attribute types are
+.B SHF_ALLOC
+and
+.BR SHF_WRITE .
+.TP
+.I .data1
+This section holds initialized data that contribute to the program's
+memory image.
+This section is of type
+.BR SHT_PROGBITS .
+The attribute types are
+.B SHF_ALLOC
+and
+.BR SHF_WRITE .
+.TP
+.I .debug
+This section holds information for symbolic debugging.
+The contents
+are unspecified.
+This section is of type
+.BR SHT_PROGBITS .
+No attribute types are used.
+.TP
+.I .dtors
+This section holds initialized pointers to the C++ destructor functions.
+This section is of type
+.BR SHT_PROGBITS .
+The attribute types are
+.B SHF_ALLOC
+and
+.BR SHF_WRITE .
+.TP
+.I .dynamic
+This section holds dynamic linking information.
+The section's attributes
+will include the
+.B SHF_ALLOC
+bit.
+Whether the
+.B SHF_WRITE
+bit is set is processor-specific.
+This section is of type
+.BR SHT_DYNAMIC .
+See the attributes above.
+.TP
+.I .dynstr
+This section holds strings needed for dynamic linking, most commonly
+the strings that represent the names associated with symbol table entries.
+This section is of type
+.BR SHT_STRTAB .
+The attribute type used is
+.BR SHF_ALLOC .
+.TP
+.I .dynsym
+This section holds the dynamic linking symbol table.
+This section is of type
+.BR SHT_DYNSYM .
+The attribute used is
+.BR SHF_ALLOC .
+.TP
+.I .fini
+This section holds executable instructions that contribute to the process
+termination code.
+When a program exits normally the system arranges to
+execute the code in this section.
+This section is of type
+.BR SHT_PROGBITS .
+The attributes used are
+.B SHF_ALLOC
+and
+.BR SHF_EXECINSTR .
+.TP
+.I .gnu.version
+This section holds the version symbol table, an array of
+.I ElfN_Half
+elements.
+This section is of type
+.BR SHT_GNU_versym .
+The attribute type used is
+.BR SHF_ALLOC .
+.TP
+.I .gnu.version_d
+This section holds the version symbol definitions, a table of
+.I ElfN_Verdef
+structures.
+This section is of type
+.BR SHT_GNU_verdef .
+The attribute type used is
+.BR SHF_ALLOC .
+.TP
+.I .gnu.version_r
+This section holds the version symbol needed elements, a table of
+.I ElfN_Verneed
+structures.
+This section is of
+type
+.BR SHT_GNU_versym .
+The attribute type used is
+.BR SHF_ALLOC .
+.TP
+.I .got
+This section holds the global offset table.
+This section is of type
+.BR SHT_PROGBITS .
+The attributes are processor-specific.
+.TP
+.I .hash
+This section holds a symbol hash table.
+This section is of type
+.BR SHT_HASH .
+The attribute used is
+.BR SHF_ALLOC .
+.TP
+.I .init
+This section holds executable instructions that contribute to the process
+initialization code.
+When a program starts to run the system arranges to execute
+the code in this section before calling the main program entry point.
+This section is of type
+.BR SHT_PROGBITS .
+The attributes used are
+.B SHF_ALLOC
+and
+.BR SHF_EXECINSTR .
+.TP
+.I .interp
+This section holds the pathname of a program interpreter.
+If the file has
+a loadable segment that includes the section, the section's attributes will
+include the
+.B SHF_ALLOC
+bit.
+Otherwise, that bit will be off.
+This section is of type
+.BR SHT_PROGBITS .
+.TP
+.I .line
+This section holds line number information for symbolic debugging,
+which describes the correspondence between the program source and
+the machine code.
+The contents are unspecified.
+This section is of type
+.BR SHT_PROGBITS .
+No attribute types are used.
+.TP
+.I .note
+This section holds various notes.
+This section is of type
+.BR SHT_NOTE .
+No attribute types are used.
+.TP
+.I .note.ABI\-tag
+This section is used to declare the expected run-time ABI of the ELF image.
+It may include the operating system name and its run-time versions.
+This section is of type
+.BR SHT_NOTE .
+The only attribute used is
+.BR SHF_ALLOC .
+.TP
+.I .note.gnu.build\-id
+This section is used to hold an ID that uniquely identifies
+the contents of the ELF image.
+Different files with the same build ID should contain the same executable
+content.
+See the
+.B \-\-build\-id
+option to the GNU linker (\fBld\fR (1)) for more details.
+This section is of type
+.BR SHT_NOTE .
+The only attribute used is
+.BR SHF_ALLOC .
+.TP
+.I .note.GNU\-stack
+This section is used in Linux object files for declaring stack attributes.
+This section is of type
+.BR SHT_PROGBITS .
+The only attribute used is
+.BR SHF_EXECINSTR .
+This indicates to the GNU linker that the object file requires an
+executable stack.
+.TP
+.I .note.openbsd.ident
+OpenBSD native executables usually contain this section
+to identify themselves so the kernel can bypass any compatibility
+ELF binary emulation tests when loading the file.
+.TP
+.I .plt
+This section holds the procedure linkage table.
+This section is of type
+.BR SHT_PROGBITS .
+The attributes are processor-specific.
+.TP
+.I .relNAME
+This section holds relocation information as described below.
+If the file
+has a loadable segment that includes relocation, the section's attributes
+will include the
+.B SHF_ALLOC
+bit.
+Otherwise, the bit will be off.
+By convention,
+"NAME"
+is supplied by the section to which the relocations apply.
+Thus a relocation
+section for
+.B .text
+normally would have the name
+.BR .rel.text .
+This section is of type
+.BR SHT_REL .
+.TP
+.I .relaNAME
+This section holds relocation information as described below.
+If the file
+has a loadable segment that includes relocation, the section's attributes
+will include the
+.B SHF_ALLOC
+bit.
+Otherwise, the bit will be off.
+By convention,
+"NAME"
+is supplied by the section to which the relocations apply.
+Thus a relocation
+section for
+.B .text
+normally would have the name
+.BR .rela.text .
+This section is of type
+.BR SHT_RELA .
+.TP
+.I .rodata
+This section holds read-only data that typically contributes to a
+nonwritable segment in the process image.
+This section is of type
+.BR SHT_PROGBITS .
+The attribute used is
+.BR SHF_ALLOC .
+.TP
+.I .rodata1
+This section holds read-only data that typically contributes to a
+nonwritable segment in the process image.
+This section is of type
+.BR SHT_PROGBITS .
+The attribute used is
+.BR SHF_ALLOC .
+.TP
+.I .shstrtab
+This section holds section names.
+This section is of type
+.BR SHT_STRTAB .
+No attribute types are used.
+.TP
+.I .strtab
+This section holds strings, most commonly the strings that represent the
+names associated with symbol table entries.
+If the file has a loadable
+segment that includes the symbol string table, the section's attributes
+will include the
+.B SHF_ALLOC
+bit.
+Otherwise, the bit will be off.
+This section is of type
+.BR SHT_STRTAB .
+.TP
+.I .symtab
+This section holds a symbol table.
+If the file has a loadable segment
+that includes the symbol table, the section's attributes will include
+the
+.B SHF_ALLOC
+bit.
+Otherwise, the bit will be off.
+This section is of type
+.BR SHT_SYMTAB .
+.TP
+.I .text
+This section holds the
+"text",
+or executable instructions, of a program.
+This section is of type
+.BR SHT_PROGBITS .
+The attributes used are
+.B SHF_ALLOC
+and
+.BR SHF_EXECINSTR .
+.\"
+.SS String and symbol tables
+String table sections hold null-terminated character sequences, commonly
+called strings.
+The object file uses these strings to represent symbol
+and section names.
+One references a string as an index into the string
+table section.
+The first byte, which is index zero, is defined to hold
+a null byte (\[aq]\e0\[aq]).
+Similarly, a string table's last byte is defined to
+hold a null byte, ensuring null termination for all strings.
+.P
+An object file's symbol table holds information needed to locate and
+relocate a program's symbolic definitions and references.
+A symbol table
+index is a subscript into this array.
+.P
+.in +4n
+.EX
+typedef struct {
+    uint32_t      st_name;
+    Elf32_Addr    st_value;
+    uint32_t      st_size;
+    unsigned char st_info;
+    unsigned char st_other;
+    uint16_t      st_shndx;
+} Elf32_Sym;
+.EE
+.in
+.P
+.in +4n
+.EX
+typedef struct {
+    uint32_t      st_name;
+    unsigned char st_info;
+    unsigned char st_other;
+    uint16_t      st_shndx;
+    Elf64_Addr    st_value;
+    uint64_t      st_size;
+} Elf64_Sym;
+.EE
+.in
+.P
+The 32-bit and 64-bit versions have the same members, just in a different
+order.
+.TP
+.I st_name
+This member holds an index into the object file's symbol string table,
+which holds character representations of the symbol names.
+If the value
+is nonzero, it represents a string table index that gives the symbol
+name.
+Otherwise, the symbol has no name.
+.TP
+.I st_value
+This member gives the value of the associated symbol.
+.TP
+.I st_size
+Many symbols have associated sizes.
+This member holds zero if the symbol
+has no size or an unknown size.
+.TP
+.I st_info
+This member specifies the symbol's type and binding attributes:
+.RS
+.TP
+.B STT_NOTYPE
+The symbol's type is not defined.
+.TP
+.B STT_OBJECT
+The symbol is associated with a data object.
+.TP
+.B STT_FUNC
+The symbol is associated with a function or other executable code.
+.TP
+.B STT_SECTION
+The symbol is associated with a section.
+Symbol table entries of
+this type exist primarily for relocation and normally have
+.B STB_LOCAL
+bindings.
+.TP
+.B STT_FILE
+By convention, the symbol's name gives the name of the source file
+associated with the object file.
+A file symbol has
+.B STB_LOCAL
+bindings, its section index is
+.BR SHN_ABS ,
+and it precedes the other
+.B STB_LOCAL
+symbols of the file, if it is present.
+.TP
+.B STT_LOPROC
+.TQ
+.B STT_HIPROC
+Values in the inclusive range
+.RB [ STT_LOPROC ,
+.BR STT_HIPROC ]
+are reserved for processor-specific semantics.
+.TP
+.B STB_LOCAL
+Local symbols are not visible outside the object file containing their
+definition.
+Local symbols of the same name may exist in multiple files
+without interfering with each other.
+.TP
+.B STB_GLOBAL
+Global symbols are visible to all object files being combined.
+One file's
+definition of a global symbol will satisfy another file's undefined
+reference to the same symbol.
+.TP
+.B STB_WEAK
+Weak symbols resemble global symbols, but their definitions have lower
+precedence.
+.TP
+.B STB_LOPROC
+.TQ
+.B STB_HIPROC
+Values in the inclusive range
+.RB [ STB_LOPROC ,
+.BR STB_HIPROC ]
+are reserved for processor-specific semantics.
+.RE
+.IP
+There are macros for packing and unpacking the binding and type fields:
+.RS
+.TP
+.BI ELF32_ST_BIND( info )
+.TQ
+.BI ELF64_ST_BIND( info )
+Extract a binding from an
+.I st_info
+value.
+.TP
+.BI ELF32_ST_TYPE( info )
+.TQ
+.BI ELF64_ST_TYPE( info )
+Extract a type from an
+.I st_info
+value.
+.TP
+.BI ELF32_ST_INFO( bind ", " type )
+.TQ
+.BI ELF64_ST_INFO( bind ", " type )
+Convert a binding and a type into an
+.I st_info
+value.
+.RE
+.TP
+.I st_other
+This member defines the symbol visibility.
+.RS
+.TP
+.PD 0
+.B STV_DEFAULT
+Default symbol visibility rules.
+Global and weak symbols are available to other modules;
+references in the local module can be interposed
+by definitions in other modules.
+.TP
+.B STV_INTERNAL
+Processor-specific hidden class.
+.TP
+.B STV_HIDDEN
+Symbol is unavailable to other modules;
+references in the local module always resolve to the local symbol
+(i.e., the symbol can't be interposed by definitions in other modules).
+.TP
+.B STV_PROTECTED
+Symbol is available to other modules,
+but references in the local module always resolve to the local symbol.
+.PD
+.P
+There are macros for extracting the visibility type:
+.P
+.BR ELF32_ST_VISIBILITY (other)
+or
+.BR ELF64_ST_VISIBILITY (other)
+.RE
+.TP
+.I st_shndx
+Every symbol table entry is
+"defined"
+in relation to some section.
+This member holds the relevant section
+header table index.
+.\"
+.SS Relocation entries (Rel & Rela)
+Relocation is the process of connecting symbolic references with
+symbolic definitions.
+Relocatable files must have information that
+describes how to modify their section contents, thus allowing executable
+and shared object files to hold the right information for a process's
+program image.
+Relocation entries are these data.
+.P
+Relocation structures that do not need an addend:
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf32_Addr r_offset;
+    uint32_t   r_info;
+} Elf32_Rel;
+.EE
+.in
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf64_Addr r_offset;
+    uint64_t   r_info;
+} Elf64_Rel;
+.EE
+.in
+.P
+Relocation structures that need an addend:
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf32_Addr r_offset;
+    uint32_t   r_info;
+    int32_t    r_addend;
+} Elf32_Rela;
+.EE
+.in
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf64_Addr r_offset;
+    uint64_t   r_info;
+    int64_t    r_addend;
+} Elf64_Rela;
+.EE
+.in
+.TP
+.I r_offset
+This member gives the location at which to apply the relocation action.
+For a relocatable file, the value is the byte offset from the beginning
+of the section to the storage unit affected by the relocation.
+For an
+executable file or shared object, the value is the virtual address of
+the storage unit affected by the relocation.
+.TP
+.I r_info
+This member gives both the symbol table index with respect to which the
+relocation must be made and the type of relocation to apply.
+Relocation
+types are processor-specific.
+When the text refers to a relocation
+entry's relocation type or symbol table index, it means the result of
+applying
+.B ELF[32|64]_R_TYPE
+or
+.BR ELF[32|64]_R_SYM ,
+respectively, to the entry's
+.I r_info
+member.
+.TP
+.I r_addend
+This member specifies a constant addend used to compute the value to be
+stored into the relocatable field.
+.\"
+.SS Dynamic tags (Dyn)
+The
+.I .dynamic
+section contains a series of structures that hold relevant
+dynamic linking information.
+The
+.I d_tag
+member controls the interpretation
+of
+.IR d_un .
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf32_Sword    d_tag;
+    union {
+        Elf32_Word d_val;
+        Elf32_Addr d_ptr;
+    } d_un;
+} Elf32_Dyn;
+extern Elf32_Dyn _DYNAMIC[];
+.EE
+.in
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf64_Sxword    d_tag;
+    union {
+        Elf64_Xword d_val;
+        Elf64_Addr  d_ptr;
+    } d_un;
+} Elf64_Dyn;
+extern Elf64_Dyn _DYNAMIC[];
+.EE
+.in
+.TP
+.I d_tag
+This member may have any of the following values:
+.RS
+.TP 12
+.B DT_NULL
+Marks end of dynamic section
+.TP
+.B DT_NEEDED
+String table offset to name of a needed library
+.TP
+.B DT_PLTRELSZ
+Size in bytes of PLT relocation entries
+.TP
+.B DT_PLTGOT
+Address of PLT and/or GOT
+.TP
+.B DT_HASH
+Address of symbol hash table
+.TP
+.B DT_STRTAB
+Address of string table
+.TP
+.B DT_SYMTAB
+Address of symbol table
+.TP
+.B DT_RELA
+Address of Rela relocation table
+.TP
+.B DT_RELASZ
+Size in bytes of the Rela relocation table
+.TP
+.B DT_RELAENT
+Size in bytes of a Rela relocation table entry
+.TP
+.B DT_STRSZ
+Size in bytes of string table
+.TP
+.B DT_SYMENT
+Size in bytes of a symbol table entry
+.TP
+.B DT_INIT
+Address of the initialization function
+.TP
+.B DT_FINI
+Address of the termination function
+.TP
+.B DT_SONAME
+String table offset to name of shared object
+.TP
+.B DT_RPATH
+String table offset to library search path (deprecated)
+.TP
+.B DT_SYMBOLIC
+Alert linker to search this shared object before the executable for symbols
+.TP
+.B DT_REL
+Address of Rel relocation table
+.TP
+.B DT_RELSZ
+Size in bytes of Rel relocation table
+.TP
+.B DT_RELENT
+Size in bytes of a Rel table entry
+.TP
+.B DT_PLTREL
+Type of relocation entry to which the PLT refers (Rela or Rel)
+.TP
+.B DT_DEBUG
+Undefined use for debugging
+.TP
+.B DT_TEXTREL
+Absence of this entry indicates that no relocation entries should
+apply to a nonwritable segment
+.TP
+.B DT_JMPREL
+Address of relocation entries associated solely with the PLT
+.TP
+.B DT_BIND_NOW
+Instruct dynamic linker to process all relocations before
+transferring control to the executable
+.TP
+.B DT_RUNPATH
+String table offset to library search path
+.TP
+.B DT_LOPROC
+.TQ
+.B DT_HIPROC
+Values in the inclusive range
+.RB [ DT_LOPROC ,
+.BR DT_HIPROC ]
+are reserved for processor-specific semantics
+.RE
+.TP
+.I d_val
+This member represents integer values with various interpretations.
+.TP
+.I d_ptr
+This member represents program virtual addresses.
+When interpreting
+these addresses, the actual address should be computed based on the
+original file value and memory base address.
+Files do not contain
+relocation entries to fixup these addresses.
+.TP
+.I _DYNAMIC
+Array containing all the dynamic structures in the
+.I .dynamic
+section.
+This is automatically populated by the linker.
+.\" GABI ELF Reference for Note Sections:
+.\" http://www.sco.com/developers/gabi/latest/ch5.pheader.html#note_section
+.\"
+.\" Note that it implies the sizes and alignments of notes depend on the ELF
+.\" size (e.g. 32-bit ELFs have three 4-byte words and use 4-byte alignment
+.\" while 64-bit ELFs use 8-byte words & alignment), but that is not the case
+.\" in the real world.  Notes always have three 4-byte words as can be seen
+.\" in the source links below (remember that Elf64_Word is a 32-bit quantity).
+.\" glibc:    https://sourceware.org/git/?p=glibc.git;a=blob;f=elf/elf.h;h=9e59b3275917549af0cebe1f2de9ded3b7b10bf2#l1173
+.\" binutils: https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=binutils/readelf.c;h=274ddd17266aef6e4ad1f67af8a13a21500ff2af#l15943
+.\" Linux:    https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/elf.h?h=v4.8#n422
+.\" Solaris:  https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-18048.html
+.\" FreeBSD:  https://svnweb.freebsd.org/base/head/sys/sys/elf_common.h?revision=303677&view=markup#l33
+.\" NetBSD:   https://www.netbsd.org/docs/kernel/elf-notes.html
+.\" OpenBSD:  https://github.com/openbsd/src/blob/master/sys/sys/exec_elf.h#L533
+.\"
+.SS Notes (Nhdr)
+ELF notes allow for appending arbitrary information for the system to use.
+They are largely used by core files
+.RI ( e_type
+of
+.BR ET_CORE ),
+but many projects define their own set of extensions.
+For example,
+the GNU tool chain uses ELF notes to pass information from
+the linker to the C library.
+.P
+Note sections contain a series of notes (see the
+.I struct
+definitions below).
+Each note is followed by the name field (whose length is defined in
+\fIn_namesz\fR) and then by the descriptor field (whose length is defined in
+\fIn_descsz\fR) and whose starting address has a 4 byte alignment.
+Neither field is defined in the note struct due to their arbitrary lengths.
+.P
+An example for parsing out two consecutive notes should clarify their layout
+in memory:
+.P
+.in +4n
+.EX
+void *memory, *name, *desc;
+Elf64_Nhdr *note, *next_note;
+\&
+/* The buffer is pointing to the start of the section/segment. */
+note = memory;
+\&
+/* If the name is defined, it follows the note. */
+name = note\->n_namesz == 0 ? NULL : memory + sizeof(*note);
+\&
+/* If the descriptor is defined, it follows the name
+   (with alignment). */
+\&
+desc = note\->n_descsz == 0 ? NULL :
+       memory + sizeof(*note) + ALIGN_UP(note\->n_namesz, 4);
+\&
+/* The next note follows both (with alignment). */
+next_note = memory + sizeof(*note) +
+                     ALIGN_UP(note\->n_namesz, 4) +
+                     ALIGN_UP(note\->n_descsz, 4);
+.EE
+.in
+.P
+Keep in mind that the interpretation of
+.I n_type
+depends on the namespace defined by the
+.I n_namesz
+field.
+If the
+.I n_namesz
+field is not set (e.g., is 0), then there are two sets of notes:
+one for core files and one for all other ELF types.
+If the namespace is unknown, then tools will usually fallback to these sets
+of notes as well.
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf32_Word n_namesz;
+    Elf32_Word n_descsz;
+    Elf32_Word n_type;
+} Elf32_Nhdr;
+.EE
+.in
+.P
+.in +4n
+.EX
+typedef struct {
+    Elf64_Word n_namesz;
+    Elf64_Word n_descsz;
+    Elf64_Word n_type;
+} Elf64_Nhdr;
+.EE
+.in
+.TP
+.I n_namesz
+The length of the name field in bytes.
+The contents will immediately follow this note in memory.
+The name is null terminated.
+For example, if the name is "GNU", then
+.I n_namesz
+will be set to 4.
+.TP
+.I n_descsz
+The length of the descriptor field in bytes.
+The contents will immediately follow the name field in memory.
+.TP
+.I n_type
+Depending on the value of the name field, this member may have any of the
+following values:
+.RS
+.TP 5
+.B Core files (e_type = ET_CORE)
+Notes used by all core files.
+These are highly operating system or architecture specific and often require
+close coordination with kernels, C libraries, and debuggers.
+These are used when the namespace is the default (i.e.,
+.I n_namesz
+will be set to 0), or a fallback when the namespace is unknown.
+.RS
+.TP 21
+.PD 0
+.B NT_PRSTATUS
+prstatus struct
+.TP
+.B NT_FPREGSET
+fpregset struct
+.TP
+.B NT_PRPSINFO
+prpsinfo struct
+.TP
+.B NT_PRXREG
+prxregset struct
+.TP
+.B NT_TASKSTRUCT
+task structure
+.TP
+.B NT_PLATFORM
+String from sysinfo(SI_PLATFORM)
+.TP
+.B NT_AUXV
+auxv array
+.TP
+.B NT_GWINDOWS
+gwindows struct
+.TP
+.B NT_ASRS
+asrset struct
+.TP
+.B NT_PSTATUS
+pstatus struct
+.TP
+.B NT_PSINFO
+psinfo struct
+.TP
+.B NT_PRCRED
+prcred struct
+.TP
+.B NT_UTSNAME
+utsname struct
+.TP
+.B NT_LWPSTATUS
+lwpstatus struct
+.TP
+.B NT_LWPSINFO
+lwpinfo struct
+.TP
+.B NT_PRFPXREG
+fprxregset struct
+.TP
+.B NT_SIGINFO
+siginfo_t (size might increase over time)
+.TP
+.B NT_FILE
+Contains information about mapped files
+.TP
+.B NT_PRXFPREG
+user_fxsr_struct
+.TP
+.B NT_PPC_VMX
+PowerPC Altivec/VMX registers
+.TP
+.B NT_PPC_SPE
+PowerPC SPE/EVR registers
+.TP
+.B NT_PPC_VSX
+PowerPC VSX registers
+.TP
+.B NT_386_TLS
+i386 TLS slots (struct user_desc)
+.TP
+.B NT_386_IOPERM
+x86 io permission bitmap (1=deny)
+.TP
+.B NT_X86_XSTATE
+x86 extended state using xsave
+.TP
+.B NT_S390_HIGH_GPRS
+s390 upper register halves
+.TP
+.B NT_S390_TIMER
+s390 timer register
+.TP
+.B NT_S390_TODCMP
+s390 time-of-day (TOD) clock comparator register
+.TP
+.B NT_S390_TODPREG
+s390 time-of-day (TOD) programmable register
+.TP
+.B NT_S390_CTRS
+s390 control registers
+.TP
+.B NT_S390_PREFIX
+s390 prefix register
+.TP
+.B NT_S390_LAST_BREAK
+s390 breaking event address
+.TP
+.B NT_S390_SYSTEM_CALL
+s390 system call restart data
+.TP
+.B NT_S390_TDB
+s390 transaction diagnostic block
+.TP
+.B NT_ARM_VFP
+ARM VFP/NEON registers
+.TP
+.B NT_ARM_TLS
+ARM TLS register
+.TP
+.B NT_ARM_HW_BREAK
+ARM hardware breakpoint registers
+.TP
+.B NT_ARM_HW_WATCH
+ARM hardware watchpoint registers
+.TP
+.B NT_ARM_SYSTEM_CALL
+ARM system call number
+.PD
+.RE
+.TP
+.B n_name = GNU
+Extensions used by the GNU tool chain.
+.RS
+.TP
+.B NT_GNU_ABI_TAG
+Operating system (OS) ABI information.
+The desc field will be 4 words:
+.IP
+.PD 0
+.RS
+.IP [0] 5
+OS descriptor
+(\fBELF_NOTE_OS_LINUX\fR, \fBELF_NOTE_OS_GNU\fR, and so on)`
+.IP [1]
+major version of the ABI
+.IP [2]
+minor version of the ABI
+.IP [3]
+subminor version of the ABI
+.RE
+.PD
+.TP
+.B NT_GNU_HWCAP
+Synthetic hwcap information.
+The desc field begins with two words:
+.IP
+.PD 0
+.RS
+.IP [0] 5
+number of entries
+.IP [1]
+bit mask of enabled entries
+.RE
+.PD
+.IP
+Then follow variable-length entries, one byte followed by a null-terminated
+hwcap name string.
+The byte gives the bit number to test if enabled, (1U << bit) & bit mask.
+.TP
+.B NT_GNU_BUILD_ID
+Unique build ID as generated by the GNU
+.BR ld (1)
+.B \-\-build\-id
+option.
+The desc consists of any nonzero number of bytes.
+.TP
+.B NT_GNU_GOLD_VERSION
+The desc contains the GNU Gold linker version used.
+.RE
+.TP
+.B Default/unknown namespace (e_type != ET_CORE)
+These are used when the namespace is the default (i.e.,
+.I n_namesz
+will be set to 0), or a fallback when the namespace is unknown.
+.RS
+.TP 12
+.PD 0
+.B NT_VERSION
+A version string of some sort.
+.TP
+.B NT_ARCH
+Architecture information.
+.PD
+.RE
+.RE
+.SH NOTES
+.\" OpenBSD
+.\" ELF support first appeared in
+.\" OpenBSD 1.2,
+.\" although not all supported platforms use it as the native
+.\" binary file format.
+ELF first appeared in
+System V.
+The ELF format is an adopted standard.
+.P
+The extensions for
+.IR e_phnum ,
+.IR e_shnum ,
+and
+.I e_shstrndx
+respectively are
+Linux extensions.
+Sun, BSD, and AMD64 also support them; for further information,
+look under SEE ALSO.
+.\" .SH AUTHORS
+.\" The original version of this manual page was written by
+.\" .An Jeroen Ruigrok van der Werven
+.\" .Aq asmodai@FreeBSD.org
+.\" with inspiration from BSDi's
+.\" .Bsx
+.\" .Nm elf
+.\" man page.
+.SH SEE ALSO
+.BR as (1),
+.BR elfedit (1),
+.BR gdb (1),
+.BR ld (1),
+.BR nm (1),
+.BR objcopy (1),
+.BR objdump (1),
+.BR patchelf (1),
+.BR readelf (1),
+.BR size (1),
+.BR strings (1),
+.BR strip (1),
+.BR execve (2),
+.BR dl_iterate_phdr (3),
+.BR core (5),
+.BR ld.so (8)
+.P
+Hewlett-Packard,
+.IR "Elf-64 Object File Format" .
+.P
+Santa Cruz Operation,
+.IR "System V Application Binary Interface" .
+.P
+UNIX System Laboratories,
+"Object Files",
+.IR "Executable and Linking Format (ELF)" .
+.P
+Sun Microsystems,
+.IR "Linker and Libraries Guide" .
+.P
+AMD64 ABI Draft,
+.IR "System V Application Binary Interface AMD64 Architecture Processor Supplement" .
diff --git a/man/man5/erofs.5 b/man/man5/erofs.5
new file mode 100644
index 000000000..3611baffa
--- /dev/null
+++ b/man/man5/erofs.5
@@ -0,0 +1,97 @@
+.\" Copyright (c) 2016 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH erofs 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+erofs \- the Enhanced Read-Only File System
+.SH DESCRIPTION
+.B erofs
+is a create-once read-only filesystem,
+with support for compression and a multi-device backing store.
+.P
+There are two inode formats:
+.IP \[bu] 3
+32-byte compact with 16-bit UID/GID,
+32-bit file size,
+and no file times
+.PD 0
+.IP \[bu]
+64-byte extended with 32-bit UID/GID,
+64-bit file size,
+and a modification time
+.RI ( st_mtim ).
+.PD
+.\" See fs/erofs/super.c:shmem_parse_options for options it supports.
+.SS Mount options
+.TP
+.B user_xattr
+.TQ
+.B nouser_xattr
+Controls whether
+.I user
+extended attributes are exposed.
+Defaults to yes.
+.TP
+.B acl
+.TQ
+.B noacl
+Controls whether POSIX
+.BR acl (5)s
+are exposed.
+Defaults to yes.
+.TP
+.BR cache_strategy = disabled | readahead | readaround
+Cache allocation for compressed files:
+never, if reading from start of file, regardless of position.
+Defaults to
+.BR readaround .
+.TP
+.B dax
+.TQ
+.BR dax = always | never
+Direct Access control.
+If
+.B always
+and the source device supports DAX, uncompressed non-inlined files
+will be read directly, without going through the page cache.
+.B dax
+is a synonym for
+.BR always .
+Defaults to unset, which is equivalent to
+.BR never .
+.TP
+.BR device = \fIblobdev\fP
+Add extra device holding some of the data.
+Must be given as many times and in the same order as
+.B \-\-blobdev
+was to
+.BR mkfs.erofs (1).
+.\" Nominally there's a device_table feature and it somehow scans(?) for them,
+.\" cf. super.c:erofs_scan_devices(), but I haven't gotten it to work
+.TP
+.BR domain_id = \fIdid\fP
+.TQ
+.BR fsid = \fIid\fP
+Control CacheFiles on-demand read support.
+To be documented.
+.SH VERSIONS
+.B erofs
+images are versioned through the use of feature flags;
+these are listed in the
+.B \-E
+section of
+.BR mkfs.erofs (1),
+.SH CONFIGURATION
+Linux must be configured with the
+.B CONFIG_EROFS_FS
+option to mount EROFS filesystems.
+There are sub-configuration items that restrict the availability
+of some of the parameters above.
+.SH SEE ALSO
+.BR mkfs.erofs (1),
+.BR fsck.erofs (1),
+.BR dump.erofs (1)
+.P
+.I Documentation/filesystems/erofs.txt
+in the Linux source.
diff --git a/man/man5/filesystems.5 b/man/man5/filesystems.5
new file mode 100644
index 000000000..4e9378c74
--- /dev/null
+++ b/man/man5/filesystems.5
@@ -0,0 +1,227 @@
+.\" Copyright 1996 Daniel Quinlan (Daniel.Quinlan@linux.org)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2007-12-14 mtk Added Reiserfs, XFS, JFS.
+.\"
+.TH filesystems 5 (date) "Linux man-pages (unreleased)"
+.nh
+.SH NAME
+filesystems \- Linux filesystem types: ext, ext2, ext3, ext4, hpfs, iso9660,
+JFS, minix, msdos, ncpfs nfs, ntfs, proc, Reiserfs, smb, sysv, umsdos, vfat,
+XFS, xiafs
+.SH DESCRIPTION
+When, as is customary, the
+.B proc
+filesystem is mounted on
+.IR /proc ,
+you can find in the file
+.I /proc/filesystems
+which filesystems your kernel currently supports;
+see
+.BR proc (5)
+for more details.
+There is also a legacy
+.BR sysfs (2)
+system call (whose availability is controlled by the
+.\" commit: 6af9f7bf3c399e0ab1eee048e13572c6d4e15fe9
+.B CONFIG_SYSFS_SYSCALL
+kernel build configuration option since Linux 3.15)
+that enables enumeration of the currently available filesystem types
+regardless of
+.I /proc
+availability and/or sanity.
+.P
+If you need a currently unsupported filesystem, insert the corresponding
+kernel module or recompile the kernel.
+.P
+In order to use a filesystem, you have to
+.I mount
+it; see
+.BR mount (2)
+and
+.BR mount (8).
+.P
+The following list provides a
+short description of the available or historically available
+filesystems in the Linux kernel.
+See the kernel documentation for a comprehensive
+description of all options and limitations.
+.TP
+.B erofs
+is the Enhanced Read-Only File System, stable since Linux 5.4.
+.\" commit 47e4937a4a7ca4184fd282791dfee76c6799966a moves it out of staging
+See
+.BR erofs (5).
+.TP
+.B ext
+is an elaborate extension of the
+.B minix
+filesystem.
+It has been completely superseded by the second version
+of the extended filesystem
+.RB ( ext2 )
+and has been removed from the kernel (in Linux 2.1.21).
+.TP
+.B ext2
+is a disk filesystem that was used by Linux for fixed disks
+as well as removable media.
+The second extended filesystem was designed as an extension of the
+extended filesystem
+.RB ( ext ).
+See
+.BR ext2 (5).
+.TP
+.B ext3
+is a journaling version of the
+.B ext2
+filesystem.
+It is easy to
+switch back and forth between
+.B ext2
+and
+.BR ext3 .
+See
+.BR ext3 (5).
+.TP
+.B ext4
+is a set of upgrades to
+.B ext3
+including substantial performance and
+reliability enhancements,
+plus large increases in volume, file, and directory size limits.
+See
+.BR ext4 (5).
+.TP
+.B hpfs
+is the High Performance Filesystem, used in OS/2.
+This filesystem is
+read-only under Linux due to the lack of available documentation.
+.TP
+.B iso9660
+is a CD-ROM filesystem type conforming to the ISO/IEC\~9660 standard.
+.RS
+.TP
+.B "High Sierra"
+Linux supports High Sierra, the precursor to the ISO/IEC\~9660 standard for
+CD-ROM filesystems.
+It is automatically recognized within the
+.B iso9660
+filesystem support under Linux.
+.TP
+.B "Rock Ridge"
+Linux also supports the System Use Sharing Protocol records specified
+by the Rock Ridge Interchange Protocol.
+They are used to further describe the files in the
+.B iso9660
+filesystem to a UNIX host, and provide information such as long
+filenames, UID/GID, POSIX permissions, and devices.
+It is automatically recognized within the
+.B iso9660
+filesystem support under Linux.
+.RE
+.TP
+.B JFS
+is a journaling filesystem, developed by IBM,
+that was integrated into Linux 2.4.24.
+.TP
+.B minix
+is the filesystem used in the Minix operating system, the first to run
+under Linux.
+It has a number of shortcomings, including a 64\ MB partition size
+limit, short filenames, and a single timestamp.
+It remains useful for floppies and RAM disks.
+.TP
+.B msdos
+is the filesystem used by DOS, Windows, and some OS/2 computers.
+.B msdos
+filenames can be no longer than 8 characters, followed by an
+optional period and 3 character extension.
+.TP
+.B ncpfs
+is a network filesystem that supports the NCP protocol,
+used by Novell NetWare.
+It was removed from the kernel in Linux 4.17.
+.IP
+To use
+.BR ncpfs ,
+you need special programs, which can be found at
+.UR ftp://ftp.gwdg.de\:/pub\:/linux\:/misc\:/ncpfs
+.UE .
+.TP
+.B nfs
+is the network filesystem used to access disks located on remote computers.
+.TP
+.B ntfs
+is the filesystem native to Microsoft Windows NT,
+supporting features like ACLs, journaling, encryption, and so on.
+.TP
+.B proc
+is a pseudo filesystem which is used as an interface to kernel data
+structures rather than reading and interpreting
+.IR /dev/kmem .
+In particular, its files do not take disk space.
+See
+.BR proc (5).
+.TP
+.B Reiserfs
+is a journaling filesystem, designed by Hans Reiser,
+that was integrated into Linux 2.4.1.
+.TP
+.B smb
+is a network filesystem that supports the SMB protocol, used by
+Windows.
+See
+.UR https://www.samba.org\:/samba\:/smbfs/
+.UE .
+.TP
+.B sysv
+is an implementation of the System V/Coherent filesystem for Linux.
+It implements all of Xenix FS, System V/386 FS, and Coherent FS.
+.TP
+.B umsdos
+is an extended DOS filesystem used by Linux.
+It adds capability for
+long filenames, UID/GID, POSIX permissions, and special files
+(devices, named pipes, etc.) under the DOS filesystem, without
+sacrificing compatibility with DOS.
+.TP
+.B tmpfs
+is a filesystem whose contents reside in virtual memory.
+Since the files on such filesystems typically reside in RAM,
+file access is extremely fast.
+See
+.BR tmpfs (5).
+.TP
+.B vfat
+is an extended FAT filesystem used by Microsoft Windows95 and Windows NT.
+.B vfat
+adds the capability to use long filenames under the MSDOS filesystem.
+.TP
+.B XFS
+is a journaling filesystem, developed by SGI,
+that was integrated into Linux 2.4.20.
+.TP
+.B xiafs
+was designed and implemented to be a stable, safe filesystem by
+extending the Minix filesystem code.
+It provides the basic most
+requested features without undue complexity.
+The
+.B xiafs
+filesystem is no longer actively developed or maintained.
+It was removed from the kernel in Linux 2.1.21.
+.SH SEE ALSO
+.BR fuse (4),
+.BR btrfs (5),
+.BR ext2 (5),
+.BR ext3 (5),
+.BR ext4 (5),
+.BR nfs (5),
+.BR proc (5),
+.BR sysfs (5),
+.BR tmpfs (5),
+.BR xfs (5),
+.BR fsck (8),
+.BR mkfs (8),
+.BR mount (8)
diff --git a/man/man5/fs.5 b/man/man5/fs.5
new file mode 100644
index 000000000..3ec300ca2
--- /dev/null
+++ b/man/man5/fs.5
@@ -0,0 +1 @@
+.so man5/filesystems.5
diff --git a/man/man5/ftpusers.5 b/man/man5/ftpusers.5
new file mode 100644
index 000000000..cca6ec73c
--- /dev/null
+++ b/man/man5/ftpusers.5
@@ -0,0 +1,42 @@
+.\" Copyright (c) 2000 Christoph J. Thompson <obituary@linuxbe.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ftpusers 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ftpusers \- list of users that may not log in via the FTP daemon
+.SH DESCRIPTION
+The text file
+.B ftpusers
+contains a list of users that may not log in using the
+File Transfer Protocol (FTP) server daemon.
+This file is used not merely for
+system administration purposes but also for improving security within a TCP/IP
+networked environment.
+.P
+The
+.B ftpusers
+file will typically contain a list of the users that
+either have no business using ftp or have too many privileges to be allowed
+to log in through the FTP server daemon.
+Such users usually include root, daemon, bin, uucp, and news.
+.P
+If your FTP server daemon doesn't use
+.BR ftpusers ,
+then it is suggested that you read its documentation to find out how to
+block access for certain users.
+Washington University FTP server Daemon
+(wuftpd) and Professional FTP Daemon (proftpd) are known to make use of
+.BR ftpusers .
+.SS Format
+The format of
+.B ftpusers
+is very simple.
+There is one account name (or username) per line.
+Lines starting with a # are ignored.
+.SH FILES
+.I /etc/ftpusers
+.SH SEE ALSO
+.BR passwd (5),
+.BR proftpd (8),
+.BR wuftpd (8)
diff --git a/man/man5/gai.conf.5 b/man/man5/gai.conf.5
new file mode 100644
index 000000000..f7dfd07a8
--- /dev/null
+++ b/man/man5/gai.conf.5
@@ -0,0 +1,89 @@
+.\" Copyright (C) 2006 Red Hat, Inc. All rights reserved.
+.\" Author: Ulrich Drepper <drepper@redhat.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.\"
+.TH gai.conf 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+gai.conf \- getaddrinfo(3) configuration file
+.SH DESCRIPTION
+A call to
+.BR getaddrinfo (3)
+might return multiple answers.
+According to RFC\ 3484 these answers must be sorted so that
+the answer with the highest success rate is first in the list.
+The RFC provides an algorithm for the sorting.
+The static rules are not always adequate, though.
+For this reason,
+the RFC also requires that system administrators should have the possibility
+to dynamically change the sorting.
+For the glibc implementation, this can be achieved with the
+.I /etc/gai.conf
+file.
+.P
+Each line in the configuration file consists of a keyword and its parameters.
+White spaces in any place are ignored.
+Lines starting with \[aq]#\[aq] are comments and are ignored.
+.P
+The keywords currently recognized are:
+.TP
+\fBlabel\fR \fInetmask\fR \fIprecedence\fR
+The value is added to the label table used in the RFC\ 3484 sorting.
+If any \fBlabel\fR definition is present in the configuration file,
+the default table is not used.
+All the label definitions
+of the default table which are to be maintained have to be duplicated.
+Following the keyword,
+the line has to contain a network mask and a precedence value.
+.TP
+\fBprecedence\fR \fInetmask\fR \fIprecedence\fR
+This keyword is similar to \fBlabel\fR, but instead the value is added
+to the precedence table as specified in RFC\ 3484.
+Once again, the
+presence of a single \fBprecedence\fR line in the configuration file
+causes the default table to not be used.
+.TP
+\fBreload\fR <\fByes\fR|\fBno\fR>
+This keyword controls whether a process checks whether the configuration
+file has been changed since the last time it was read.
+If the value is
+"\fByes\fR", the file is reread.
+This might cause problems in multithreaded
+applications and is generally a bad idea.
+The default is "\fBno\fR".
+.TP
+\fBscopev4\fR \fImask\fR \fIvalue\fR
+Add another rule to the RFC\ 3484 scope table for IPv4 address.
+By default, the scope IDs described in section 3.2 in RFC\ 3438 are used.
+Changing these defaults should hardly ever be necessary.
+.SH FILES
+\fI/etc/gai.conf\fR
+.SH VERSIONS
+The
+.I gai.conf
+.\" Added in 2006
+file is supported since glibc 2.5.
+.SH EXAMPLES
+The default table according to RFC\ 3484 would be specified with the
+following configuration file:
+.P
+.in +4n
+.EX
+label  ::1/128       0
+label  ::/0          1
+label  2002::/16     2
+label ::/96          3
+label ::ffff:0:0/96  4
+precedence  ::1/128       50
+precedence  ::/0          40
+precedence  2002::/16     30
+precedence ::/96          20
+precedence ::ffff:0:0/96  10
+.EE
+.in
+.\" .SH AUTHOR
+.\" Ulrich Drepper <drepper@redhat.com>
+.\"
+.SH SEE ALSO
+.BR getaddrinfo (3),
+RFC\ 3484
diff --git a/man/man5/group.5 b/man/man5/group.5
new file mode 100644
index 000000000..2df94017a
--- /dev/null
+++ b/man/man5/group.5
@@ -0,0 +1,55 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:06:03 1993 by Rik Faith (faith@cs.unc.edu)
+.TH group 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+group \- user group file
+.SH DESCRIPTION
+The
+.I /etc/group
+file is a text file that defines the groups on the system.
+There is one entry per line, with the following format:
+.P
+.in +4n
+.EX
+group_name:password:GID:user_list
+.EE
+.in
+.P
+The fields are as follows:
+.TP
+.I group_name
+the name of the group.
+.TP
+.I password
+the (encrypted) group password.
+If this field is empty, no password is needed.
+.TP
+.I GID
+the numeric group ID.
+.TP
+.I user_list
+a list of the usernames that are members of this group, separated by commas.
+.SH FILES
+.I /etc/group
+.SH BUGS
+As the 4.2BSD
+.BR initgroups (3)
+man page says: no one seems to keep
+.I /etc/group
+up-to-date.
+.SH SEE ALSO
+.BR chgrp (1),
+.BR gpasswd (1),
+.BR groups (1),
+.BR login (1),
+.BR newgrp (1),
+.BR sg (1),
+.BR getgrent (3),
+.BR getgrnam (3),
+.BR gshadow (5),
+.BR passwd (5),
+.BR vigr (8)
diff --git a/man/man5/host.conf.5 b/man/man5/host.conf.5
new file mode 100644
index 000000000..1f88665bc
--- /dev/null
+++ b/man/man5/host.conf.5
@@ -0,0 +1,204 @@
+.\" Copyright (c) 1997 Martin Schulze (joey@infodrom.north.de)
+.\" Much of the text is copied from the manpage of resolv+(8).
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2003-08-23 Martin Schulze <joey@infodrom.org> Updated according to glibc 2.3.2
+.TH host.conf 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+host.conf \- resolver configuration file
+.SH DESCRIPTION
+The file
+.I /etc/host.conf
+contains configuration information specific to the resolver library.
+It should contain one configuration keyword per line, followed by
+appropriate configuration information.
+The following keywords are recognized:
+.TP
+.I trim
+This keyword may be listed more than once.
+Each time it should be
+followed by a list of domains, separated by colons (\[aq]:\[aq]), semicolons
+(\[aq];\[aq]) or commas (\[aq],\[aq]), with the leading dot.
+When set, the
+resolver library will automatically trim the given domain name from the
+end of any hostname resolved via DNS.
+This is intended for use with
+local hosts and domains.
+(Related note:
+.I trim
+will not affect hostnames gathered via NIS or the
+.BR hosts (5)
+file.
+Care should be taken to
+ensure that the first hostname for each entry in the hosts file is
+fully qualified or unqualified, as appropriate for the local
+installation.)
+.TP
+.I multi
+Valid values are
+.IR on " and " off .
+If set to
+.IR on ,
+the resolver library will return all valid addresses for a host that
+appears in the
+.I /etc/hosts
+file,
+instead of only the first.
+This is
+.I off
+by default, as it may cause a substantial performance loss at sites
+with large hosts files.
+.TP
+.I reorder
+Valid values are
+.IR on " and " off .
+If set to
+.IR on ,
+the resolver library
+will attempt to reorder host addresses so that local addresses
+(i.e., on the same subnet) are listed first when a
+.BR gethostbyname (3)
+is performed.
+Reordering is done for all lookup methods.
+The default value is
+.IR off .
+.SH ENVIRONMENT
+The following environment variables can be used to allow users to
+override the behavior which is configured in
+.IR /etc/host.conf :
+.TP
+.B RESOLV_HOST_CONF
+If set, this variable points to a file that should be read instead of
+.IR /etc/host.conf .
+.TP
+.B RESOLV_MULTI
+Overrides the
+.I multi
+command.
+.TP
+.B RESOLV_REORDER
+Overrides the
+.I reorder
+command.
+.TP
+.B RESOLV_ADD_TRIM_DOMAINS
+A list of domains,
+separated by
+colons (\[aq]:\[aq]), semicolons (\[aq];\[aq]), or commas (\[aq],\[aq]),
+with the leading dot,
+which will be added to the list of domains that should be trimmed.
+.TP
+.B RESOLV_OVERRIDE_TRIM_DOMAINS
+A list of domains,
+separated by
+colons (\[aq]:\[aq]), semicolons (\[aq];\[aq]), or commas (\[aq],\[aq]),
+with the leading dot,
+which will replace the list of domains that should be trimmed.
+Overrides the
+.I trim
+command.
+.SH FILES
+.TP
+.I /etc/host.conf
+Resolver configuration file
+.TP
+.I /etc/resolv.conf
+Resolver configuration file
+.TP
+.I /etc/hosts
+Local hosts database
+.SH NOTES
+The following differences exist compared to the original implementation.
+A new command
+.I spoof
+and a new environment variable
+.B RESOLV_SPOOF_CHECK
+can take arguments like
+.IR off ", " nowarn ", and " warn .
+Line comments can appear anywhere and not only at the beginning of a line.
+.SS Historical
+The
+.BR nsswitch.conf (5)
+file is the modern way of controlling the order of host lookups.
+.P
+In glibc 2.4 and earlier, the following keyword is recognized:
+.TP
+.I order
+This keyword specifies how host lookups are to be performed.
+It should be followed by one or more lookup methods, separated by commas.
+Valid methods are
+.IR bind ", " hosts ", and " nis .
+.TP
+.B RESOLV_SERV_ORDER
+Overrides the
+.I order
+command.
+.P
+.\" commit 7d68cdaa4f748e87ee921f587ee2d483db624b3d
+Since glibc 2.0.7, and up through glibc 2.24,
+the following keywords and environment variable
+have been recognized but never implemented:
+.TP
+.I nospoof
+Valid values are
+.IR on " and " off .
+If set to
+.IR on ,
+the resolver library will attempt to prevent hostname spoofing to
+enhance the security of
+.BR rlogin " and " rsh .
+It works as follows: after performing a host address lookup,
+the resolver library will perform a hostname lookup for that address.
+If the two hostnames
+do not match, the query fails.
+The default value is
+.IR off .
+.TP
+.I spoofalert
+Valid values are
+.IR on " and " off .
+If this option is set to
+.I on
+and the
+.I nospoof
+option is also set,
+the resolver library will log a warning of the error via the
+syslog facility.
+The default value is
+.IR off .
+.TP
+.I spoof
+Valid values are
+.IR off ", " nowarn ", and " warn .
+If this option is set to
+.IR off ,
+spoofed addresses are permitted and no warnings will be emitted
+via the syslog facility.
+If this option is set to
+.IR warn ,
+the resolver library will attempt to prevent hostname spoofing to
+enhance the security and log a warning of the error via the syslog
+facility.
+If this option is set to
+.IR nowarn ,
+the resolver library will attempt to prevent hostname spoofing to
+enhance the security but not emit warnings via the syslog facility.
+Setting this option to anything else is equal to setting it to
+.IR nowarn .
+.TP
+.B RESOLV_SPOOF_CHECK
+Overrides the
+.IR nospoof ", " spoofalert ", and " spoof
+commands in the same way as the
+.I spoof
+command is parsed.
+Valid values are
+.IR off ", " nowarn ", and " warn .
+.SH SEE ALSO
+.BR gethostbyname (3),
+.BR hosts (5),
+.BR nsswitch.conf (5),
+.BR resolv.conf (5),
+.BR hostname (7),
+.BR named (8)
diff --git a/man/man5/hosts.5 b/man/man5/hosts.5
new file mode 100644
index 000000000..515a1a269
--- /dev/null
+++ b/man/man5/hosts.5
@@ -0,0 +1,122 @@
+.\" Copyright (c) 2000 Manoj Srivastava <srivasta@debian.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Minor polishing, aeb
+.\" Modified, 2002-06-16, Mike Coleman
+.\"
+.TH hosts 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hosts \- static table lookup for hostnames
+.SH SYNOPSIS
+.nf
+.B /etc/hosts
+.fi
+.SH DESCRIPTION
+This manual page describes the format of the
+.I /etc/hosts
+file.
+This file is a simple text file that associates IP addresses
+with hostnames, one line per IP address.
+For each host a single
+line should be present with the following information:
+.RS
+.P
+IP_address canonical_hostname [aliases...]
+.RE
+.P
+The IP address can conform to either IPv4 or IPv6.
+Fields of the entry are separated by any number of blanks and/or
+tab characters.
+Text from a "#" character until the end of the line is
+a comment, and is ignored.
+Host names may contain only alphanumeric
+characters, minus signs ("\-"), and periods (".").
+They must begin with an
+alphabetic character and end with an alphanumeric character.
+Optional aliases provide for name changes, alternate spellings,
+shorter hostnames, or generic hostnames (for example,
+.IR localhost ).
+If required, a host may have two separate entries in this file;
+one for each version of the Internet Protocol (IPv4 and IPv6).
+.P
+The Berkeley Internet Name Domain (BIND) Server implements the
+Internet name server for UNIX systems.
+It augments or replaces the
+.I /etc/hosts
+file or hostname lookup, and frees a host from relying on
+.I /etc/hosts
+being up to date and complete.
+.P
+In modern systems, even though the host table has been superseded by
+DNS, it is still widely used for:
+.TP
+.B bootstrapping
+Most systems have a small host table containing the name and address
+information for important hosts on the local network.
+This is useful
+when DNS is not running, for example during system bootup.
+.TP
+.B NIS
+Sites that use NIS use the host table as input to the NIS host
+database.
+Even though NIS can be used with DNS, most NIS sites still
+use the host table with an entry for all local hosts as a backup.
+.TP
+.B isolated nodes
+Very small sites that are isolated from the network use the host table
+instead of DNS.
+If the local information rarely changes, and the
+network is not connected to the Internet, DNS offers little
+advantage.
+.SH FILES
+.I /etc/hosts
+.SH NOTES
+Modifications to this file normally take effect immediately,
+except in cases where the file is cached by applications.
+.SS Historical notes
+RFC\ 952 gave the original format for the host table, though it has
+since changed.
+.P
+Before the advent of DNS, the host table was the only way of resolving
+hostnames on the fledgling Internet.
+Indeed, this file could be
+created from the official host data base maintained at the Network
+Information Control Center (NIC), though local changes were often
+required to bring it up to date regarding unofficial aliases and/or
+unknown hosts.
+The NIC no longer maintains the hosts.txt files,
+though looking around at the time of writing (circa 2000), there are
+historical hosts.txt files on the WWW.
+I just found three, from 92,
+94, and 95.
+.SH EXAMPLES
+.EX
+# The following lines are desirable for IPv4 capable hosts
+127.0.0.1       localhost
+\&
+# 127.0.1.1 is often used for the FQDN of the machine
+127.0.1.1       thishost.example.org   thishost
+192.168.1.10    foo.example.org        foo
+192.168.1.13    bar.example.org        bar
+146.82.138.7    master.debian.org      master
+209.237.226.90  www.opensource.org
+\&
+# The following lines are desirable for IPv6 capable hosts
+::1             localhost ip6\-localhost ip6\-loopback
+ff02::1         ip6\-allnodes
+ff02::2         ip6\-allrouters
+.EE
+.SH SEE ALSO
+.BR hostname (1),
+.BR resolver (3),
+.BR host.conf (5),
+.BR resolv.conf (5),
+.BR resolver (5),
+.BR hostname (7),
+.BR named (8)
+.P
+Internet RFC\ 952
+.\" .SH AUTHOR
+.\" This manual page was written by Manoj Srivastava <srivasta@debian.org>,
+.\" for the Debian GNU/Linux system.
diff --git a/man/man5/hosts.equiv.5 b/man/man5/hosts.equiv.5
new file mode 100644
index 000000000..35bbded4e
--- /dev/null
+++ b/man/man5/hosts.equiv.5
@@ -0,0 +1,212 @@
+.\" Copyright (c) 1995 Peter Tobias <tobias@et-inf.fho-emden.de>
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.TH hosts.equiv 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hosts.equiv \- list of hosts and users that are granted "trusted"
+.B r
+command access to your system
+.SH DESCRIPTION
+The file
+.I /etc/hosts.equiv
+allows or denies hosts and users to use
+the \fBr\fP-commands (e.g.,
+.BR rlogin ,
+.BR rsh ,
+or
+.BR rcp )
+without
+supplying a password.
+.P
+The file uses the following format:
+.TP
+\fI+|[\-]hostname|+@netgroup|\-@netgroup\fP \fI[+|[\-]username|+@netgroup|\-@netgroup]\fP
+.P
+The
+.I hostname
+is the name of a host which is logically equivalent
+to the local host.
+Users logged into that host are allowed to access
+like-named user accounts on the local host without supplying a password.
+The
+.I hostname
+may be (optionally) preceded by a plus (+) sign.
+If the plus sign is used alone, it allows any host to access your system.
+You can explicitly deny access to a host by preceding the
+.I hostname
+by a minus (\-) sign.
+Users from that host must always supply additional credentials,
+including possibly a password.
+For security reasons you should always
+use the FQDN of the hostname and not the short hostname.
+.P
+The
+.I username
+entry grants a specific user access to all user
+accounts (except root) without supplying a password.
+That means the
+user is NOT restricted to like-named accounts.
+The
+.I username
+may
+be (optionally) preceded by a plus (+) sign.
+You can also explicitly
+deny access to a specific user by preceding the
+.I username
+with
+a minus (\-) sign.
+This says that the user is not trusted no matter
+what other entries for that host exist.
+.P
+Netgroups can be specified by preceding the netgroup by an @ sign.
+.P
+Be extremely careful when using the plus (+) sign.
+A simple typographical
+error could result in a standalone plus sign.
+A standalone plus sign is
+a wildcard character that means "any host"!
+.SH FILES
+.I /etc/hosts.equiv
+.SH NOTES
+Some systems will honor the contents of this file only when it has owner
+root and no write permission for anybody else.
+Some exceptionally
+paranoid systems even require that there be no other hard links to the file.
+.P
+Modern systems use the Pluggable Authentication Modules library (PAM).
+With PAM a standalone plus sign is considered a wildcard
+character which means "any host" only when the word
+.I promiscuous
+is added to the auth component line in your PAM file for
+the particular service
+.RB "(e.g., " rlogin ).
+.SH EXAMPLES
+Below are some example
+.I /etc/host.equiv
+or
+.I \[ti]/.rhosts
+files.
+.P
+Allow any user to log in from any host:
+.P
+.in +4n
+.EX
++
+.EE
+.in
+.P
+Allow any user from
+.I host
+with a matching local account to log in:
+.P
+.in +4n
+.EX
+host
+.EE
+.in
+.P
+Note: the use of
+.I +host
+is never a valid syntax,
+including attempting to specify that any user from the host is allowed.
+.P
+Allow any user from
+.I host
+to log in:
+.P
+.in +4n
+.EX
+host +
+.EE
+.in
+.P
+Note: this is distinct from the previous example
+since it does not require a matching local account.
+.P
+Allow
+.I user
+from
+.I host
+to log in as any non-root user:
+.P
+.in +4n
+.EX
+host user
+.EE
+.in
+.P
+Allow all users with matching local accounts from
+.I host
+to log in except for
+.IR baduser :
+.P
+.in +4n
+.EX
+host \-baduser
+host
+.EE
+.in
+.P
+Deny all users from
+.IR host :
+.P
+.in +4n
+.EX
+\-host
+.EE
+.in
+.P
+Note: the use of
+.I "\-host\ \-user"
+is never a valid syntax,
+including attempting to specify that a particular user from the host
+is not trusted.
+.P
+Allow all users with matching local accounts on all hosts in a
+.IR netgroup :
+.P
+.in +4n
+.EX
++@netgroup
+.EE
+.in
+.P
+Disallow all users on all hosts in a
+.IR netgroup :
+.P
+.in +4n
+.EX
+\-@netgroup
+.EE
+.in
+.P
+Allow all users in a
+.I netgroup
+to log in from
+.I host
+as any non-root user:
+.P
+.in +4n
+.EX
+host +@netgroup
+.EE
+.in
+.P
+Allow all users with matching local accounts on all hosts in a
+.I netgroup
+except
+.IR baduser :
+.P
+.in +4n
+.EX
++@netgroup \-baduser
++@netgroup
+.EE
+.in
+.P
+Note: the deny statements must always precede the allow statements because
+the file is processed sequentially until the first matching rule is found.
+.SH SEE ALSO
+.BR rhosts (5),
+.BR rlogind (8),
+.BR rshd (8)
diff --git a/man/man5/intro.5 b/man/man5/intro.5
new file mode 100644
index 000000000..2babd6280
--- /dev/null
+++ b/man/man5/intro.5
@@ -0,0 +1,23 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:06:52 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Jan 14 00:34:09 1996 by Andries Brouwer (aeb@cwi.nl)
+.TH intro 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to file formats and filesystems
+.SH DESCRIPTION
+Section 5 of the manual describes various file formats,
+as well as the corresponding C structures, if any.
+.P
+In addition,
+this section contains a number of pages that document various filesystems.
+.SH NOTES
+.SS Authors and copyright conditions
+Look at the header of the manual page source for the author(s) and copyright
+conditions.
+Note that these can be different from page to page!
+.SH SEE ALSO
+.BR standards (7)
diff --git a/man/man5/issue.5 b/man/man5/issue.5
new file mode 100644
index 000000000..13d2b83b3
--- /dev/null
+++ b/man/man5/issue.5
@@ -0,0 +1,24 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sun Jul 25 11:06:22 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.TH issue 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+issue \- prelogin message and identification file
+.SH DESCRIPTION
+.I /etc/issue
+is a text file which contains a message or
+system identification to be printed before the login prompt.
+It may contain various \fB@\fP\fIchar\fP and \fB\e\fP\fIchar\fP
+sequences, if supported by the
+.BR getty -type
+program employed on the system.
+.SH FILES
+.I /etc/issue
+.SH SEE ALSO
+.BR motd (5),
+.BR agetty (8),
+.BR mingetty (8)
diff --git a/man/man5/locale.5 b/man/man5/locale.5
new file mode 100644
index 000000000..39c93c88b
--- /dev/null
+++ b/man/man5/locale.5
@@ -0,0 +1,1316 @@
+.\" Copyright (C) 1994  Jochen Hein (Hein@Student.TU-Clausthal.de)
+.\" Copyright (C) 2008  Petr Baudis (pasky@suse.cz)
+.\" Copyright (C) 2014 Michael Kerrisk <mtk@manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2008-06-17 Petr Baudis <pasky@suse.cz>
+.\"     LC_TIME: Describe first_weekday and first_workday
+.\"
+.TH locale 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+locale \- describes a locale definition file
+.SH DESCRIPTION
+The
+.B locale
+definition file contains all the information that the
+.BR localedef (1)
+command needs to convert it into the binary locale database.
+.P
+The definition files consist of sections which each describe a
+locale category in detail.
+See
+.BR locale (7)
+for additional details for these categories.
+.SS Syntax
+The locale definition file starts with a header that may consist
+of the following keywords:
+.TP
+.I escape_char
+is followed by a character that should be used as the
+escape-character for the rest of the file to mark characters that
+should be interpreted in a special way.
+It defaults to the backslash (\e).
+.TP
+.I comment_char
+is followed by a character that will be used as the
+comment-character for the rest of the file.
+It defaults to the number sign (#).
+.P
+The locale definition has one part for each locale category.
+Each part can be copied from another existing locale or
+can be defined from scratch.
+If the category should be copied,
+the only valid keyword in the definition is
+.I copy
+followed by the name of the locale in double quotes which should be
+copied.
+The exceptions for this rule are
+.B LC_COLLATE
+and
+.B LC_CTYPE
+where a
+.I copy
+statement can be followed by locale-specific rules and selected overrides.
+.P
+When defining a locale or a category from scratch, an existing system-
+provided locale definition file should be used as a reference to follow
+common glibc conventions.
+.SS Locale category sections
+The following category sections are defined by POSIX:
+.IP \[bu] 3
+.B LC_CTYPE
+.IP \[bu]
+.B LC_COLLATE
+.IP \[bu]
+.B LC_MESSAGES
+.IP \[bu]
+.B LC_MONETARY
+.IP \[bu]
+.B LC_NUMERIC
+.IP \[bu]
+.B LC_TIME
+.P
+In addition, since glibc 2.2,
+the GNU C library supports the following nonstandard categories:
+.IP \[bu] 3
+.B LC_ADDRESS
+.IP \[bu]
+.B LC_IDENTIFICATION
+.IP \[bu]
+.B LC_MEASUREMENT
+.IP \[bu]
+.B LC_NAME
+.IP \[bu]
+.B LC_PAPER
+.IP \[bu]
+.B LC_TELEPHONE
+.P
+See
+.BR locale (7)
+for a more detailed description of each category.
+.SS LC_ADDRESS
+The definition starts with the string
+.I LC_ADDRESS
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I postal_fmt
+followed by a string containing field descriptors that define
+the format used for postal addresses in the locale.
+The following field descriptors are recognized:
+.RS
+.TP
+%n
+Person's name, possibly constructed with the
+.B LC_NAME
+.I name_fmt
+keyword (since glibc 2.24).
+.TP 4
+%a
+Care of person, or organization.
+.TP
+%f
+Firm name.
+.TP
+%d
+Department name.
+.TP
+%b
+Building name.
+.TP
+%s
+Street or block (e.g., Japanese) name.
+.TP
+%h
+House number or designation.
+.TP
+%N
+Insert an end-of-line if the previous descriptor's value was not an empty
+string; otherwise ignore.
+.TP
+%t
+Insert a space if the previous descriptor's value was not an empty string;
+otherwise ignore.
+.TP
+%r
+Room number, door designation.
+.TP
+%e
+Floor number.
+.TP
+%C
+Country designation, from the
+.I country_post
+keyword.
+.TP
+%l
+Local township within town or city (since glibc 2.24).
+.TP
+%z
+Zip number, postal code.
+.TP
+%T
+Town, city.
+.TP
+%S
+State, province, or prefecture.
+.TP
+%c
+Country, as taken from data record.
+.P
+Each field descriptor may have an \[aq]R\[aq] after
+the \[aq]%\[aq] to specify that the
+information is taken from a Romanized version string of the
+entity.
+.RE
+.TP
+.I country_name
+followed by the country name in the language of the current document
+(e.g., "Deutschland" for the
+.B de_DE
+locale).
+.TP
+.I country_post
+followed by the abbreviation of the country (see CERT_MAILCODES).
+.TP
+.I country_ab2
+followed by the two-letter abbreviation of the country (ISO\~3166).
+.TP
+.I country_ab3
+followed by the three-letter abbreviation of the country (ISO\~3166).
+.TP
+.I country_num
+followed by the numeric country code (ISO\~3166).
+.TP
+.I country_car
+followed by the international license plate country code.
+.TP
+.I country_isbn
+followed by the ISBN code (for books).
+.TP
+.I lang_name
+followed by the language name in the language of the current document.
+.TP
+.I lang_ab
+followed by the two-letter abbreviation of the language (ISO\~639).
+.TP
+.I lang_term
+followed by the three-letter abbreviation of the language (ISO\~639-2/T).
+.TP
+.I lang_lib
+followed by the three-letter abbreviation of the language for library
+use (ISO\~639-2/B).
+Applications should in general prefer
+.I lang_term
+over
+.IR lang_lib .
+.P
+The
+.B LC_ADDRESS
+definition ends with the string
+.IR "END LC_ADDRESS" .
+.SS LC_CTYPE
+The definition starts with the string
+.I LC_CTYPE
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I upper
+followed by a list of uppercase letters.
+The letters
+.B A
+through
+.B Z
+are included automatically.
+Characters also specified as
+.BR cntrl ,
+.BR digit ,
+.BR punct ,
+or
+.B space
+are not allowed.
+.TP
+.I lower
+followed by a list of lowercase letters.
+The letters
+.B a
+through
+.B z
+are included automatically.
+Characters also specified as
+.BR cntrl ,
+.BR digit ,
+.BR punct ,
+or
+.B space
+are not allowed.
+.TP
+.I alpha
+followed by a list of letters.
+All character specified as either
+.B upper
+or
+.B lower
+are automatically included.
+Characters also specified as
+.BR cntrl ,
+.BR digit ,
+.BR punct ,
+or
+.B space
+are not allowed.
+.TP
+.I digit
+followed by the characters classified as numeric digits.
+Only the
+digits
+.B 0
+through
+.B 9
+are allowed.
+They are included by default in this class.
+.TP
+.I space
+followed by a list of characters defined as white-space
+characters.
+Characters also specified as
+.BR upper ,
+.BR lower ,
+.BR alpha ,
+.BR digit ,
+.BR graph ,
+or
+.B xdigit
+are not allowed.
+The characters
+.BR <space> ,
+.BR <form-feed> ,
+.BR <newline> ,
+.BR <carriage-return> ,
+.BR <tab> ,
+and
+.B <vertical-tab>
+are automatically included.
+.TP
+.I cntrl
+followed by a list of control characters.
+Characters also specified as
+.BR upper ,
+.BR lower ,
+.BR alpha ,
+.BR digit ,
+.BR punct ,
+.BR graph ,
+.BR print ,
+or
+.B xdigit
+are not allowed.
+.TP
+.I punct
+followed by a list of punctuation characters.
+Characters also
+specified as
+.BR upper ,
+.BR lower ,
+.BR alpha ,
+.BR digit ,
+.BR cntrl ,
+.BR xdigit ,
+or the
+.B <space>
+character are not allowed.
+.TP
+.I graph
+followed by a list of printable characters, not including the
+.B <space>
+character.
+The characters defined as
+.BR upper ,
+.BR lower ,
+.BR alpha ,
+.BR digit ,
+.BR xdigit ,
+and
+.B punct
+are automatically included.
+Characters also specified as
+.B cntrl
+are not allowed.
+.TP
+.I print
+followed by a list of printable characters, including the
+.B <space>
+character.
+The characters defined as
+.BR upper ,
+.BR lower ,
+.BR alpha ,
+.BR digit ,
+.BR xdigit ,
+.BR punct ,
+and the
+.B <space>
+character are automatically included.
+Characters also specified as
+.B cntrl
+are not allowed.
+.TP
+.I xdigit
+followed by a list of characters classified as hexadecimal
+digits.
+The decimal digits must be included followed by one or
+more set of six characters in ascending order.
+The following
+characters are included by default:
+.B 0
+through
+.BR 9 ,
+.B a
+through
+.BR f ,
+.B A
+through
+.BR F .
+.TP
+.I blank
+followed by a list of characters classified as
+.BR blank .
+The characters
+.B <space>
+and
+.B <tab>
+are automatically included.
+.TP
+.I charclass
+followed by a list of locale-specific character class names
+which are then to be defined in the locale.
+.TP
+.I toupper
+followed by a list of mappings from lowercase to uppercase
+letters.
+Each mapping is a pair of a lowercase and an uppercase letter
+separated with a
+.B ,
+and enclosed in parentheses.
+.TP
+.I tolower
+followed by a list of mappings from uppercase to lowercase
+letters.
+If the keyword tolower is not present, the reverse of the
+toupper list is used.
+.TP
+.I map totitle
+followed by a list of mapping pairs of
+characters and letters
+to be used in titles (headings).
+.TP
+.I class
+followed by a locale-specific character class definition,
+starting with the class name followed by the characters
+belonging to the class.
+.TP
+.I charconv
+followed by a list of locale-specific character mapping names
+which are then to be defined in the locale.
+.TP
+.I outdigit
+followed by a list of alternate output digits for the locale.
+.TP
+.I map to_inpunct
+followed by a list of mapping pairs of
+alternate digits and separators
+for input digits for the locale.
+.TP
+.I map to_outpunct
+followed by a list of mapping pairs of
+alternate separators
+for output for the locale.
+.TP
+.I translit_start
+marks the start of the transliteration rules section.
+The section can contain the
+.I include
+keyword in the beginning followed by
+locale-specific rules and overrides.
+Any rule specified in the locale file
+will override any rule
+copied or included from other files.
+In case of duplicate rule definitions in the locale file,
+only the first rule is used.
+.IP
+A transliteration rule consist of a character to be transliterated
+followed by a list of transliteration targets separated by semicolons.
+The first target which can be presented in the target character set
+is used, if none of them can be used the
+.I default_missing
+character will be used instead.
+.TP
+.I include
+in the transliteration rules section includes
+a transliteration rule file
+(and optionally a repertoire map file).
+.TP
+.I default_missing
+in the transliteration rules section
+defines the default character to be used for
+transliteration where none of the targets cannot be presented
+in the target character set.
+.TP
+.I translit_end
+marks the end of the transliteration rules.
+.P
+The
+.B LC_CTYPE
+definition ends with the string
+.IR "END LC_CTYPE" .
+.SS LC_COLLATE
+Note that glibc does not support all POSIX-defined options,
+only the options described below are supported (as of glibc 2.23).
+.P
+The definition starts with the string
+.I LC_COLLATE
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I coll_weight_max
+followed by the number representing used collation levels.
+This keyword is recognized but ignored by glibc.
+.TP
+.I collating\-element
+followed by the definition of a collating-element symbol
+representing a multicharacter collating element.
+.TP
+.I collating\-symbol
+followed by the definition of a collating symbol
+that can be used in collation order statements.
+.TP
+.I define
+followed by
+.B string
+to be evaluated in an
+.I ifdef
+.B string
+/
+.I else
+/
+.I endif
+construct.
+.TP
+.I reorder\-after
+followed by a redefinition of a collation rule.
+.TP
+.I reorder\-end
+marks the end of the redefinition of a collation rule.
+.TP
+.I reorder\-sections\-after
+followed by a script name to reorder listed scripts after.
+.TP
+.I reorder\-sections\-end
+marks the end of the reordering of sections.
+.TP
+.I script
+followed by a declaration of a script.
+.TP
+.I symbol\-equivalence
+followed by a collating-symbol to be equivalent to another defined
+collating-symbol.
+.P
+The collation rule definition starts with a line:
+.TP
+.I order_start
+followed by a list of keywords chosen from
+.BR forward ,
+.BR backward ,
+or
+.BR position .
+The order definition consists of lines that describe the collation
+order and is terminated with the keyword
+.IR order_end .
+.P
+The
+.B LC_COLLATE
+definition ends with the string
+.IR "END LC_COLLATE" .
+.SS LC_IDENTIFICATION
+The definition starts with the string
+.I LC_IDENTIFICATION
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I title
+followed by the title of the locale document
+(e.g., "Maori language locale for New Zealand").
+.TP
+.I source
+followed by the name of the organization that maintains this document.
+.TP
+.I address
+followed by the address of the organization that maintains this document.
+.TP
+.I contact
+followed by the name of the contact person at
+the organization that maintains this document.
+.TP
+.I email
+followed by the email address of the person or
+organization that maintains this document.
+.TP
+.I tel
+followed by the telephone number (in international format)
+of the organization that maintains this document.
+As of glibc 2.24, this keyword is deprecated in favor of
+other contact methods.
+.TP
+.I fax
+followed by the fax number (in international format)
+of the organization that maintains this document.
+As of glibc 2.24, this keyword is deprecated in favor of
+other contact methods.
+.TP
+.I language
+followed by the name of the language to which this document applies.
+.TP
+.I territory
+followed by the name of the country/geographic extent
+to which this document applies.
+.TP
+.I audience
+followed by a description of the audience for which this document is
+intended.
+.TP
+.I application
+followed by a description of any special application
+for which this document is intended.
+.TP
+.I abbreviation
+followed by the short name for provider of the source of this document.
+.TP
+.I revision
+followed by the revision number of this document.
+.TP
+.I date
+followed by the revision date of this document.
+.P
+In addition, for each of the categories defined by the document,
+there should be a line starting with the keyword
+.IR category ,
+followed by:
+.IP (1) 5
+a string that identifies this locale category definition,
+.IP (2)
+a semicolon, and
+.IP (3)
+one of the
+.B LC_*
+identifiers.
+.P
+The
+.B LC_IDENTIFICATION
+definition ends with the string
+.IR "END LC_IDENTIFICATION" .
+.SS LC_MESSAGES
+The definition starts with the string
+.I LC_MESSAGES
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I yesexpr
+followed by a regular expression that describes possible
+yes-responses.
+.TP
+.I noexpr
+followed by a regular expression that describes possible
+no-responses.
+.TP
+.I yesstr
+followed by the output string corresponding to "yes".
+.TP
+.I nostr
+followed by the output string corresponding to "no".
+.P
+The
+.B LC_MESSAGES
+definition ends with the string
+.IR "END LC_MESSAGES" .
+.SS LC_MEASUREMENT
+The definition starts with the string
+.I LC_MEASUREMENT
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I measurement
+followed by number identifying the standard used for measurement.
+The following values are recognized:
+.RS
+.TP 4
+.B 1
+Metric.
+.TP
+.B 2
+US customary measurements.
+.RE
+.P
+The
+.B LC_MEASUREMENT
+definition ends with the string
+.IR "END LC_MEASUREMENT" .
+.SS LC_MONETARY
+The definition starts with the string
+.I LC_MONETARY
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I int_curr_symbol
+followed by the international currency symbol.
+This must be a
+4-character string containing the international currency symbol as
+defined by the ISO\~4217 standard (three characters) followed by a
+separator.
+.TP
+.I currency_symbol
+followed by the local currency symbol.
+.TP
+.I mon_decimal_point
+followed by the single-character string that will be used as the
+decimal delimiter when formatting monetary quantities.
+.TP
+.I mon_thousands_sep
+followed by the single-character string that will be used as a group
+separator when formatting monetary quantities.
+.TP
+.I mon_grouping
+followed by a sequence of integers separated by semicolons that
+describe the formatting of monetary quantities.
+See
+.I grouping
+below for details.
+.TP
+.I positive_sign
+followed by a string that is used to indicate a positive sign for
+monetary quantities.
+.TP
+.I negative_sign
+followed by a string that is used to indicate a negative sign for
+monetary quantities.
+.TP
+.I int_frac_digits
+followed by the number of fractional digits that should be used when
+formatting with the
+.IR int_curr_symbol .
+.TP
+.I frac_digits
+followed by the number of fractional digits that should be used when
+formatting with the
+.IR currency_symbol .
+.TP
+.I p_cs_precedes
+followed by an integer that indicates the placement of
+.I currency_symbol
+for a nonnegative formatted monetary quantity:
+.RS
+.TP 4
+.B 0
+the symbol succeeds the value.
+.TP
+.B 1
+the symbol precedes the value.
+.RE
+.TP
+.I p_sep_by_space
+followed by an integer that indicates the separation of
+.IR currency_symbol ,
+the sign string, and the value for a nonnegative formatted monetary quantity.
+The following values are recognized:
+.RS
+.TP 4
+.B 0
+No space separates the currency symbol and the value.
+.TP
+.B 1
+If the currency symbol and the sign string are adjacent,
+a space separates them from the value;
+otherwise a space separates the currency symbol and the value.
+.TP
+.B 2
+If the currency symbol and the sign string are adjacent,
+a space separates them from the value;
+otherwise a space separates the sign string and the value.
+.RE
+.TP
+.I n_cs_precedes
+followed by an integer that indicates the placement of
+.I currency_symbol
+for a negative formatted monetary quantity.
+The same values are recognized as for
+.IR p_cs_precedes .
+.TP
+.I n_sep_by_space
+followed by an integer that indicates the separation of
+.IR currency_symbol ,
+the sign string, and the value for a negative formatted monetary quantity.
+The same values are recognized as for
+.IR p_sep_by_space .
+.TP
+.I p_sign_posn
+followed by an integer that indicates where the
+.I positive_sign
+should be placed for a nonnegative monetary quantity:
+.RS
+.TP 4
+.B 0
+Parentheses enclose the quantity and the
+.I currency_symbol
+or
+.IR int_curr_symbol .
+.TP
+.B 1
+The sign string precedes the quantity and the
+.I currency_symbol
+or the
+.IR int_curr_symbol .
+.TP
+.B 2
+The sign string succeeds the quantity and the
+.I currency_symbol
+or the
+.IR int_curr_symbol .
+.TP
+.B 3
+The sign string precedes the
+.I currency_symbol
+or the
+.IR int_curr_symbol .
+.TP
+.B 4
+The sign string succeeds the
+.I currency_symbol
+or the
+.IR int_curr_symbol .
+.RE
+.TP
+.I n_sign_posn
+followed by an integer that indicates where the
+.I negative_sign
+should be placed for a negative monetary quantity.
+The same values are recognized as for
+.IR p_sign_posn .
+.TP
+.I int_p_cs_precedes
+followed by an integer that indicates the placement of
+.I int_curr_symbol
+for a nonnegative internationally formatted monetary quantity.
+The same values are recognized as for
+.IR p_cs_precedes .
+.TP
+.I int_n_cs_precedes
+followed by an integer that indicates the placement of
+.I int_curr_symbol
+for a negative internationally formatted monetary quantity.
+The same values are recognized as for
+.IR p_cs_precedes .
+.TP
+.I int_p_sep_by_space
+followed by an integer that indicates the separation of
+.IR int_curr_symbol ,
+the sign string,
+and the value for a nonnegative internationally formatted monetary quantity.
+The same values are recognized as for
+.IR p_sep_by_space .
+.TP
+.I int_n_sep_by_space
+followed by an integer that indicates the separation of
+.IR int_curr_symbol ,
+the sign string,
+and the value for a negative internationally formatted monetary quantity.
+The same values are recognized as for
+.IR p_sep_by_space .
+.TP
+.I int_p_sign_posn
+followed by an integer that indicates where the
+.I positive_sign
+should be placed for a nonnegative
+internationally formatted monetary quantity.
+The same values are recognized as for
+.IR p_sign_posn .
+.TP
+.I int_n_sign_posn
+followed by an integer that indicates where the
+.I negative_sign
+should be placed for a negative
+internationally formatted monetary quantity.
+The same values are recognized as for
+.IR p_sign_posn .
+.P
+The
+.B LC_MONETARY
+definition ends with the string
+.IR "END LC_MONETARY" .
+.SS LC_NAME
+The definition starts with the string
+.I LC_NAME
+in the first column.
+.P
+Various keywords are allowed, but only
+.I name_fmt
+is mandatory.
+Other keywords are needed only if there is common convention to
+use the corresponding salutation in this locale.
+The allowed keywords are as follows:
+.TP
+.I name_fmt
+followed by a string containing field descriptors that define
+the format used for names in the locale.
+The following field descriptors are recognized:
+.RS
+.TP 4
+%f
+Family name(s).
+.TP
+%F
+Family names in uppercase.
+.TP
+%g
+First given name.
+.TP
+%G
+First given initial.
+.TP
+%l
+First given name with Latin letters.
+.TP
+%o
+Other shorter name.
+.TP
+%m
+Additional given name(s).
+.TP
+%M
+Initials for additional given name(s).
+.TP
+%p
+Profession.
+.TP
+%s
+Salutation, such as "Doctor".
+.TP
+%S
+Abbreviated salutation, such as "Mr." or "Dr.".
+.TP
+%d
+Salutation, using the FDCC-sets conventions.
+.\"  1 for the name_gen
+.\"	    In glibc 2.19, %d1 is used in only:
+.\"	        /home/mtk/ARCHIVE/GLIBC/glibc-2.19/localedata/locales/bem_ZM
+.\"	        /home/mtk/ARCHIVE/GLIBC/glibc-2.19/localedata/locales/zh_HK
+.\"	    In glibc 2.19, %d[2-5] appear to be not used at all
+.\"  2 for name_mr
+.\"  3 for name_mrs
+.\"  4 for name_miss
+.\"  5 for name_ms
+.TP
+%t
+If the preceding field descriptor resulted in an empty string,
+then the empty string, otherwise a space character.
+.RE
+.TP
+.I name_gen
+followed by the general salutation for any gender.
+.TP
+.I name_mr
+followed by the salutation for men.
+.TP
+.I name_mrs
+followed by the salutation for married women.
+.TP
+.I name_miss
+followed by the salutation for unmarried women.
+.TP
+.I name_ms
+followed by the salutation valid for all women.
+.P
+The
+.B LC_NAME
+definition ends with the string
+.IR "END LC_NAME" .
+.SS LC_NUMERIC
+The definition starts with the string
+.I LC_NUMERIC
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I decimal_point
+followed by the single-character string that will be used as the
+decimal delimiter when formatting numeric quantities.
+.TP
+.I thousands_sep
+followed by the single-character string that will be used as a group
+separator when formatting numeric quantities.
+.TP
+.I grouping
+followed by a sequence of integers separated by semicolons
+that describe the formatting of numeric quantities.
+.IP
+Each integer specifies the number of digits in a group.
+The first integer defines the size of the group immediately
+to the left of the decimal delimiter.
+Subsequent integers define succeeding groups to the
+left of the previous group.
+If the last integer is not \-1, then the size of the previous group
+(if any) is repeatedly used for the remainder of the digits.
+If the last integer is \-1, then no further grouping is performed.
+.P
+The
+.B LC_NUMERIC
+definition ends with the string
+.IR "END LC_NUMERIC" .
+.SS LC_PAPER
+The definition starts with the string
+.I LC_PAPER
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I height
+followed by the height, in millimeters, of the standard paper format.
+.TP
+.I width
+followed by the width, in millimeters, of the standard paper format.
+.P
+The
+.B LC_PAPER
+definition ends with the string
+.IR "END LC_PAPER" .
+.SS LC_TELEPHONE
+The definition starts with the string
+.I LC_TELEPHONE
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I tel_int_fmt
+followed by a string that contains field descriptors that identify
+the format used to dial international numbers.
+The following field descriptors are recognized:
+.RS
+.TP 4
+%a
+Area code without nationwide prefix (the prefix is often "00").
+.TP
+%A
+Area code including nationwide prefix.
+.TP
+%l
+Local number (within area code).
+.TP
+%e
+Extension (to local number).
+.TP
+%c
+Country code.
+.TP
+%C
+Alternate carrier service code used for dialing abroad.
+.TP
+%t
+If the preceding field descriptor resulted in an empty string,
+then the empty string, otherwise a space character.
+.RE
+.TP
+.I tel_dom_fmt
+followed by a string that contains field descriptors that identify
+the format used to dial domestic numbers.
+The recognized field descriptors are the same as for
+.IR tel_int_fmt .
+.TP
+.I int_select
+followed by the prefix used to call international phone numbers.
+.TP
+.I int_prefix
+followed by the prefix used from other countries to dial this country.
+.P
+The
+.B LC_TELEPHONE
+definition ends with the string
+.IR "END LC_TELEPHONE" .
+.SS LC_TIME
+The definition starts with the string
+.I LC_TIME
+in the first column.
+.P
+The following keywords are allowed:
+.TP
+.I abday
+followed by a list of abbreviated names of the days of the week.
+The list starts with the first day of the week
+as specified by
+.I week
+(Sunday by default).
+See NOTES.
+.TP
+.I day
+followed by a list of names of the days of the week.
+The list starts with the first day of the week
+as specified by
+.I week
+(Sunday by default).
+See NOTES.
+.TP
+.I abmon
+followed by a list of abbreviated month names.
+.TP
+.I mon
+followed by a list of month names.
+.TP
+.I d_t_fmt
+followed by the appropriate date and time format
+(for syntax, see
+.BR strftime (3)).
+.TP
+.I d_fmt
+followed by the appropriate date format
+(for syntax, see
+.BR strftime (3)).
+.TP
+.I t_fmt
+followed by the appropriate time format
+(for syntax, see
+.BR strftime (3)).
+.TP
+.I am_pm
+followed by the appropriate representation of the
+.B am
+and
+.B pm
+strings.
+This should be left empty for locales not using AM/PM convention.
+.TP
+.I t_fmt_ampm
+followed by the appropriate time format
+(for syntax, see
+.BR strftime (3))
+when using 12h clock format.
+This should be left empty for locales not using AM/PM convention.
+.TP
+.I era
+followed by semicolon-separated strings that define how years are
+counted and displayed for each era in the locale.
+Each string has the following format:
+.RS
+.P
+.IR direction ":" offset ":" start_date ":" end_date ":" era_name ":" era_format
+.P
+The fields are to be defined as follows:
+.TP 4
+.I direction
+Either
+.B +
+or
+.BR \- .
+.B +
+means the years closer to
+.I start_date
+have lower numbers than years closer to
+.IR end_date .
+.B \-
+means the opposite.
+.TP
+.I offset
+The number of the year closest to
+.I start_date
+in the era, corresponding to the
+.I %Ey
+descriptor (see
+.BR strptime (3)).
+.TP
+.I start_date
+The start of the era in the form of
+.IR yyyy/mm/dd .
+Years prior AD 1 are represented as negative numbers.
+.TP
+.I end_date
+The end of the era in the form of
+.IR yyyy/mm/dd ,
+or one of the two special values of
+.B \-*
+or
+.BR +* .
+.B \-*
+means the ending date is the beginning of time.
+.B +*
+means the ending date is the end of time.
+.TP
+.I era_name
+The name of the era corresponding to the
+.I %EC
+descriptor (see
+.BR strptime (3)).
+.TP
+.I era_format
+The format of the year in the era corresponding to the
+.I %EY
+descriptor (see
+.BR strptime (3)).
+.RE
+.TP
+.I era_d_fmt
+followed by the format of the date in alternative era notation,
+corresponding to the
+.I %Ex
+descriptor (see
+.BR strptime (3)).
+.TP
+.I era_t_fmt
+followed by the format of the time in alternative era notation,
+corresponding to the
+.I %EX
+descriptor (see
+.BR strptime (3)).
+.TP
+.I era_d_t_fmt
+followed by the format of the date and time in alternative era notation,
+corresponding to the
+.I %Ec
+descriptor (see
+.BR strptime (3)).
+.TP
+.I alt_digits
+followed by the alternative digits used for date and time in the locale.
+.TP
+.I week
+followed by a list of three values separated by semicolons:
+The number of days in a week (by default 7),
+a date of beginning of the week (by default corresponds to Sunday),
+and the minimal length of the first week in year (by default 4).
+Regarding the start of the week,
+.B 19971130
+shall be used for Sunday and
+.B 19971201
+shall be used for Monday.
+See NOTES.
+.TP
+.IR first_weekday " (since glibc 2.2)"
+followed by the number of the day from the
+.I day
+list to be shown as the first day of the week in calendar applications.
+The default value of
+.B 1
+corresponds to either Sunday or Monday depending
+on the value of the second
+.I week
+list item.
+See NOTES.
+.TP
+.IR first_workday " (since glibc 2.2)"
+followed by the number of the first working day from the
+.I day
+list.
+The default value is
+.BR 2 .
+See NOTES.
+.TP
+.I cal_direction
+followed by a number value that indicates the direction for the
+display of calendar dates, as follows:
+.RS
+.TP 4
+.B 1
+Left-right from top.
+.TP
+.B 2
+Top-down from left.
+.TP
+.B 3
+Right-left from top.
+.RE
+.TP
+.I date_fmt
+followed by the appropriate date representation for
+.BR date (1)
+(for syntax, see
+.BR strftime (3)).
+.P
+The
+.B LC_TIME
+definition ends with the string
+.IR "END LC_TIME" .
+.SH FILES
+.TP
+.I /usr/lib/locale/locale\-archive
+Usual default locale archive location.
+.TP
+.I /usr/share/i18n/locales
+Usual default path for locale definition files.
+.SH STANDARDS
+POSIX.2.
+.SH NOTES
+The collective GNU C library community wisdom regarding
+.IR abday ,
+.IR day ,
+.IR week ,
+.IR first_weekday ,
+and
+.I first_workday
+states at
+https://sourceware.org/glibc/wiki/Locales
+the following:
+.IP \[bu] 3
+The value of the second
+.I week
+list item specifies the base of the
+.I abday
+and
+.I day
+lists.
+.IP \[bu]
+.I first_weekday
+specifies the offset of the first day-of-week in the
+.I abday
+and
+.I day
+lists.
+.IP \[bu]
+For compatibility reasons, all glibc locales should set the value of the
+second
+.I week
+list item to
+.B 19971130
+(Sunday) and base the
+.I abday
+and
+.I day
+lists appropriately, and set
+.I first_weekday
+and
+.I first_workday
+to
+.B 1
+or
+.BR 2 ,
+depending on whether the week and work week actually starts on Sunday or
+Monday for the locale.
+.\" .SH AUTHOR
+.\" Jochen Hein (Hein@Student.TU-Clausthal.de)
+.SH SEE ALSO
+.BR iconv (1),
+.BR locale (1),
+.BR localedef (1),
+.BR localeconv (3),
+.BR newlocale (3),
+.BR setlocale (3),
+.BR strftime (3),
+.BR strptime (3),
+.BR uselocale (3),
+.BR charmap (5),
+.BR charsets (7),
+.BR locale (7),
+.BR unicode (7),
+.BR utf\-8 (7)
diff --git a/man/man5/motd.5 b/man/man5/motd.5
new file mode 100644
index 000000000..0263aca8c
--- /dev/null
+++ b/man/man5/motd.5
@@ -0,0 +1,25 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:08:16 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
+.TH motd 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+motd \- message of the day
+.SH DESCRIPTION
+The contents of
+.I /etc/motd
+are displayed by
+.BR login (1)
+after a successful login but just before it executes the login shell.
+.P
+The abbreviation "motd" stands for "message of the day", and this file
+has been traditionally used for exactly that (it requires much less disk
+space than mail to all users).
+.SH FILES
+.I /etc/motd
+.SH SEE ALSO
+.BR login (1),
+.BR issue (5)
diff --git a/man/man5/networks.5 b/man/man5/networks.5
new file mode 100644
index 000000000..8a6b49b27
--- /dev/null
+++ b/man/man5/networks.5
@@ -0,0 +1,60 @@
+.\" Copyright (c) 2001 Martin Schulze <joey@infodrom.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2008-09-04, mtk, taken from Debian downstream, with a few light edits
+.\"
+.TH networks 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+networks \- network name information
+.SH DESCRIPTION
+The file
+.I /etc/networks
+is a plain ASCII file that describes known DARPA networks and symbolic
+names for these networks.
+Each line represents a network and has the following structure:
+.P
+.RS
+.I name number aliases .\|.\|.
+.RE
+.P
+where the fields are delimited by spaces or tabs.
+Empty lines are ignored.
+The hash character (\fB#\fP) indicates the start of a comment:
+this character, and the remaining characters up to
+the end of the current line,
+are ignored by library functions that process the file.
+.P
+The field descriptions are:
+.TP
+.I name
+The symbolic name for the network.
+Network names can contain any printable characters except
+white-space characters or the comment character.
+.TP
+.I number
+The official number for this network in numbers-and-dots notation (see
+.BR inet (3)).
+The trailing ".0" (for the host component of the network address)
+may be omitted.
+.TP
+.I aliases
+Optional aliases for the network.
+.P
+This file is read by the
+.BR route (8)
+and
+.BR netstat (8)
+utilities.
+Only Class A, B, or C networks are supported, partitioned networks
+(i.e., network/26 or network/28) are not supported by this file.
+.SH FILES
+.TP
+.I /etc/networks
+The networks definition file.
+.SH SEE ALSO
+.BR getnetbyaddr (3),
+.BR getnetbyname (3),
+.BR getnetent (3),
+.BR netstat (8),
+.BR route (8)
diff --git a/man/man5/nologin.5 b/man/man5/nologin.5
new file mode 100644
index 000000000..d740bf83d
--- /dev/null
+++ b/man/man5/nologin.5
@@ -0,0 +1,22 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sun Jul 25 11:06:34 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Corrected Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond (esr@thyrsus.com)
+.TH nologin 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nologin \- prevent unprivileged users from logging into the system
+.SH DESCRIPTION
+If the file \fI/etc/nologin\fP exists and is readable,
+.BR login (1)
+will allow access only to root.
+Other users will
+be shown the contents of this file and their logins will be refused.
+This provides a simple way of temporarily disabling all unprivileged logins.
+.SH FILES
+.I /etc/nologin
+.SH SEE ALSO
+.BR login (1),
+.BR shutdown (8)
diff --git a/man/man5/nscd.conf.5 b/man/man5/nscd.conf.5
new file mode 100644
index 000000000..f5c8a3940
--- /dev/null
+++ b/man/man5/nscd.conf.5
@@ -0,0 +1,342 @@
+.\" Copyright (c) 1999, 2000 SuSE GmbH Nuernberg, Germany
+.\" Author: Thorsten Kukuk <kukuk@suse.de>
+.\" Updates: Greg Banks <gbanks@linkedin.com> Copyright (c) 2021 Microsoft Corp.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH nscd.conf 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nscd.conf \- name service cache daemon configuration file
+.SH DESCRIPTION
+The file
+.I /etc/nscd.conf
+is read from
+.BR nscd (8)
+at startup.
+Each line specifies either an attribute and a value, or an
+attribute, service, and a value.
+Fields are separated either by SPACE
+or TAB characters.
+A \[aq]#\[aq] (number sign) indicates the beginning of a
+comment; following characters, up to the end of the line,
+are not interpreted by nscd.
+.P
+Valid services are \fIpasswd\fP, \fIgroup\fP, \fIhosts\fP, \fIservices\fP,
+or \fInetgroup\fP.
+.P
+.B logfile
+.I debug-file-name
+.RS
+Specifies name of the file to which debug info should be written.
+.RE
+.P
+.B debug\-level
+.I value
+.RS
+Sets the desired debug level.
+0 hides debug info.
+1 shows general debug info.
+2 additionally shows data in cache dumps.
+3 (and above) shows all debug info.
+The default is 0.
+.RE
+.P
+.B threads
+.I number
+.RS
+This is the initial number of threads that are started to wait for
+requests.
+At least five threads will always be created.
+The number of threads may increase dynamically up to
+.B max\-threads
+in response to demand from clients,
+but never decreases.
+.RE
+.P
+.B max\-threads
+.I number
+.RS
+Specifies the maximum number of threads.
+The default is 32.
+.RE
+.P
+.B server\-user
+.I user
+.RS
+If this option is set, nscd will run as this user and not as root.
+If a separate cache for every user is used (\-S parameter), this
+option is ignored.
+.RE
+.P
+.B stat\-user
+.I user
+.RS
+Specifies the user who is allowed to request statistics.
+.RE
+.P
+.B reload\-count
+unlimited |
+.I number
+.RS
+Sets a limit on the number of times a cached entry
+gets reloaded without being used
+before it gets removed.
+The limit can take values ranging from 0 to 254;
+values 255 or higher behave the same as
+.BR unlimited .
+Limit values can be specified in either decimal
+or hexadecimal with a "0x" prefix.
+The special value
+.B unlimited
+is case-insensitive.
+The default limit is 5.
+A limit of 0 turns off the reloading feature.
+See NOTES below for further discussion of reloading.
+.RE
+.P
+.B paranoia
+.I <yes|no>
+.RS
+Enabling paranoia mode causes nscd to restart itself periodically.
+The default is no.
+.RE
+.P
+.B restart\-interval
+.I time
+.RS
+Sets the restart interval to
+.I time
+seconds
+if periodic restart is enabled by enabling
+.B paranoia
+mode.
+The default is 3600.
+.RE
+.P
+.B enable\-cache
+.I service
+.I <yes|no>
+.RS
+Enables or disables the specified
+.I service
+cache.
+The default is no.
+.RE
+.P
+.B positive\-time\-to\-live
+.I service
+.I value
+.RS
+Sets the TTL (time-to-live) for positive entries (successful queries)
+in the specified cache for
+.IR service .
+.I Value
+is in seconds.
+Larger values increase cache hit rates and reduce mean
+response times, but increase problems with cache coherence.
+Note that for some name services (including specifically DNS)
+the TTL returned from the name service is used and
+this attribute is ignored.
+.RE
+.P
+.B negative\-time\-to\-live
+.I service
+.I value
+.RS
+Sets the TTL (time-to-live) for negative entries (unsuccessful queries)
+in the specified cache for
+.IR service .
+.I Value
+is in seconds.
+Can result in significant performance improvements if there
+are several files owned by UIDs (user IDs) not in system databases (for
+example untarring the Linux kernel sources as root); should be kept small
+to reduce cache coherency problems.
+.RE
+.P
+.B suggested\-size
+.I service
+.I value
+.RS
+This is the internal hash table size,
+.I value
+should remain a prime number for optimum efficiency.
+The default is 211.
+.RE
+.P
+.B check\-files
+.I service
+.I <yes|no>
+.RS
+Enables or disables checking the file belonging to the specified
+.I service
+for changes.
+The files are
+.IR /etc/passwd ,
+.IR /etc/group ,
+.IR /etc/hosts ,
+.IR /etc/resolv.conf ,
+.IR /etc/services ,
+and
+.IR /etc/netgroup .
+The default is yes.
+.RE
+.P
+.B persistent
+.I service
+.I <yes|no>
+.RS
+Keep the content of the cache for
+.I service
+over server restarts; useful when
+.B paranoia
+mode is set.
+The default is no.
+.RE
+.P
+.B shared
+.I service
+.I <yes|no>
+.RS
+The memory mapping of the nscd databases for
+.I service
+is shared with the clients so
+that they can directly search in them instead of having to ask the
+daemon over the socket each time a lookup is performed.
+The default is no.
+Note that a cache miss will still result in
+asking the daemon over the socket.
+.RE
+.P
+.B max\-db\-size
+.I service
+.I bytes
+.RS
+The maximum allowable size, in bytes, of the database files for the
+.IR service .
+The default is 33554432.
+.RE
+.P
+.B auto\-propagate
+.I service
+.I <yes|no>
+.RS
+When set to
+.I no
+for
+.I passwd
+or
+.I group
+service, then the
+.I .byname
+requests are not added to
+.I passwd.byuid
+or
+.I group.bygid
+cache.
+This can help with tables containing multiple records for the same ID.
+The default is yes.
+This option is valid only for services
+.I passwd
+and
+.IR group .
+.RE
+.SH NOTES
+The default values stated in this manual page originate
+from the source code of
+.BR nscd (8)
+and are used if not overridden in the configuration file.
+The default values used in the configuration file of
+your distribution might differ.
+.SS Reloading
+.BR nscd (8)
+has a feature called reloading,
+whose behavior can be surprising.
+.P
+Reloading is enabled when the
+.B reload-count
+attribute has a non-zero value.
+The default value in the source code enables reloading,
+although your distribution may differ.
+.P
+When reloading is enabled,
+positive cached entries (the results of successful queries)
+do not simply expire when their TTL is up.
+Instead, at the expiry time,
+.B nscd
+will "reload",
+i.e.,
+re-issue to the name service the same query that created the cached entry,
+to get a new value to cache.
+Depending on
+.I /etc/nsswitch.conf
+this may mean that a DNS, LDAP, or NIS request is made.
+If the new query is successful,
+reloading will repeat when the new value would expire,
+until
+.B reload-count
+reloads have happened for the entry,
+and only then will it actually be removed from the cache.
+A request from a client which hits the entry will
+reset the reload counter on the entry.
+Purging the cache using
+.I nscd\~-i
+overrides the reload logic and removes the entry.
+.P
+Reloading has the effect of extending cache entry TTLs
+without compromising on cache coherency,
+at the cost of additional load on the backing name service.
+Whether this is a good idea on your system depends on
+details of your applications' behavior,
+your name service,
+and the effective TTL values of your cache entries.
+Note that for some name services
+(for example, DNS),
+the effective TTL is the value returned from the name service and
+.I not
+the value of the
+.B positive\-time\-to\-live
+attribute.
+.P
+Please consider the following advice carefully:
+.IP \[bu] 3
+If your application will make a second request for the same name,
+after more than 1 TTL but before
+.B reload\-count
+TTLs,
+and is sensitive to the latency of a cache miss,
+then reloading may be a good idea for you.
+.IP \[bu]
+If your name service is configured to return very short TTLs,
+and your applications only make requests rarely under normal circumstances,
+then reloading may result in additional load on your backing name service
+without any benefit to applications,
+which is probably a bad idea for you.
+.IP \[bu]
+If your name service capacity is limited,
+reloading may have the surprising effect of
+increasing load on your name service instead of reducing it,
+and may be a bad idea for you.
+.IP \[bu]
+Setting
+.B reload\-count
+to
+.B unlimited
+is almost never a good idea,
+as it will result in a cache that never expires entries
+and puts never-ending additional load on the backing name service.
+.P
+Some distributions have an init script for
+.BR nscd (8)
+with a
+.I reload
+command which uses
+.I nscd\~-i
+to purge the cache.
+That use of the word "reload" is entirely different
+from the "reloading" described here.
+.SH SEE ALSO
+.BR nscd (8)
+.\" .SH AUTHOR
+.\" .B nscd
+.\" was written by Thorsten Kukuk and Ulrich Drepper.
diff --git a/man/man5/nss.5 b/man/man5/nss.5
new file mode 100644
index 000000000..2ea1b4803
--- /dev/null
+++ b/man/man5/nss.5
@@ -0,0 +1,101 @@
+.\" Copyright (C) 2006 Red Hat, Inc. All rights reserved.
+.\" Author: Ulrich Drepper <drepper@redhat.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.\"
+.TH nss 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nss \- Name Service Switch configuration file
+.SH DESCRIPTION
+Each call to a function which retrieves data from a system database
+like the password or group database is handled by the Name Service
+Switch implementation in the GNU C library.
+The various services
+provided are implemented by independent modules, each of which
+naturally varies widely from the other.
+.P
+The default implementations coming with the GNU C library are by
+default conservative and do not use unsafe data.
+This might be very costly in some situations, especially when the databases
+are large.
+Some modules allow the system administrator to request
+taking shortcuts if these are known to be safe.
+It is then the system administrator's responsibility to ensure the assumption
+is correct.
+.P
+There are other modules where the implementation changed over time.
+If an implementation used to sacrifice speed for memory consumption,
+it might create problems if the preference is switched.
+.P
+The
+.I /etc/default/nss
+file contains a number of variable assignments.
+Each variable controls the behavior of one or more
+NSS modules.
+White spaces are ignored.
+Lines beginning with \[aq]#\[aq]
+are treated as comments.
+.P
+The variables currently recognized are:
+.TP
+\fBNETID_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR
+If set to TRUE, the NIS backend for the
+.BR initgroups (3)
+function will accept the information
+from the
+.I netid.byname
+NIS map as authoritative.
+This can speed up the function significantly if the
+.I group.byname
+map is large.
+The content of the
+.I netid.byname
+map is used \fBas is\fR.
+The system administrator has to make sure it is correctly generated.
+.TP
+\fBSERVICES_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR
+If set to TRUE, the NIS backend for the
+.BR getservbyname (3)
+and
+.BR getservbyname_r (3)
+functions will assume that the
+.I services.byservicename
+NIS map exists and is authoritative, particularly
+that it contains both keys with /proto and without /proto for both
+primary service names and service aliases.
+The system administrator has to make sure it is correctly generated.
+.TP
+\fBSETENT_BATCH_READ =\fR \fITRUE\fR|\fIFALSE\fR
+If set to TRUE, the NIS backend for the
+.BR setpwent (3)
+and
+.BR setgrent (3)
+functions will read the entire database at once and then
+hand out the requests one by one from memory with every corresponding
+.BR getpwent (3)
+or
+.BR getgrent (3)
+call respectively.
+Otherwise, each
+.BR getpwent (3)
+or
+.BR getgrent (3)
+call might result in a network communication with the server to get
+the next entry.
+.SH FILES
+\fI/etc/default/nss\fR
+.SH EXAMPLES
+The default configuration corresponds to the following configuration file:
+.P
+.in +4n
+.EX
+NETID_AUTHORITATIVE=FALSE
+SERVICES_AUTHORITATIVE=FALSE
+SETENT_BATCH_READ=FALSE
+.EE
+.in
+.\" .SH AUTHOR
+.\" Ulrich Drepper <drepper@redhat.com>
+.\"
+.SH SEE ALSO
+\fInsswitch.conf\fR
diff --git a/man/man5/nsswitch.conf.5 b/man/man5/nsswitch.conf.5
new file mode 100644
index 000000000..e6c26661a
--- /dev/null
+++ b/man/man5/nsswitch.conf.5
@@ -0,0 +1,427 @@
+.\" Copyright (c) 1998, 1999 Thorsten Kukuk (kukuk@vt.uni-paderborn.de)
+.\" Copyright (c) 2011, Mark R. Bannister <cambridge@users.sourceforge.net>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH nsswitch.conf 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nsswitch.conf \- Name Service Switch configuration file
+.SH DESCRIPTION
+The Name Service Switch (NSS) configuration file,
+.IR /etc/nsswitch.conf ,
+is used by the GNU C Library and certain other applications to determine
+the sources from which to obtain name-service information in
+a range of categories,
+and in what order.
+Each category of information is identified by a database name.
+.P
+The file is plain ASCII text, with columns separated by spaces or tab
+characters.
+The first column specifies the database name.
+The remaining columns describe the order of sources to query and a
+limited set of actions that can be performed by lookup result.
+.P
+The following databases are understood by the GNU C Library:
+.TP 12
+.B aliases
+Mail aliases, used by
+.BR getaliasent (3)
+and related functions.
+.TP
+.B ethers
+Ethernet numbers.
+.TP
+.B group
+Groups of users, used by
+.BR getgrent (3)
+and related functions.
+.TP
+.B hosts
+Host names and numbers, used by
+.BR gethostbyname (3)
+and related functions.
+.TP
+.B initgroups
+Supplementary group access list, used by
+.BR getgrouplist (3)
+function.
+.TP
+.B netgroup
+Network-wide list of hosts and users, used for access rules.
+C libraries before glibc 2.1 supported netgroups only over NIS.
+.TP
+.B networks
+Network names and numbers, used by
+.BR getnetent (3)
+and related functions.
+.TP
+.B passwd
+User passwords, used by
+.BR getpwent (3)
+and related functions.
+.TP
+.B protocols
+Network protocols, used by
+.BR getprotoent (3)
+and related functions.
+.TP
+.B publickey
+Public and secret keys for Secure_RPC used by NFS and NIS+.
+.TP
+.B rpc
+Remote procedure call names and numbers, used by
+.BR getrpcbyname (3)
+and related functions.
+.TP
+.B services
+Network services, used by
+.BR getservent (3)
+and related functions.
+.TP
+.B shadow
+Shadow user passwords, used by
+.BR getspnam (3)
+and related functions.
+.P
+The GNU C Library ignores databases with unknown names.
+Some applications use this to implement special handling for their own
+databases.
+For example,
+.BR sudo (8)
+consults the
+.B sudoers
+database.
+Delegation of subordinate user/group IDs
+can be configured using the
+.B subid
+database.
+Refer to
+.BR subuid (5)
+and
+.BR subgid (5)
+for more details.
+.P
+Here is an example
+.I /etc/nsswitch.conf
+file:
+.P
+.in +4n
+.EX
+passwd:         compat
+group:          compat
+shadow:         compat
+\&
+hosts:          dns [!UNAVAIL=return] files
+networks:       nis [NOTFOUND=return] files
+ethers:         nis [NOTFOUND=return] files
+protocols:      nis [NOTFOUND=return] files
+rpc:            nis [NOTFOUND=return] files
+services:       nis [NOTFOUND=return] files
+.EE
+.in
+.P
+The first column is the database name.
+The remaining columns specify:
+.IP \[bu] 3
+One or more service specifications, for example, "files", "db", or "nis".
+The order of the services on the line determines the order in which
+those services will be queried, in turn, until a result is found.
+.IP \[bu]
+Optional actions to perform if a particular result is obtained
+from the preceding service, for example, "[NOTFOUND=return]".
+.P
+The service specifications supported on your system depend on the
+presence of shared libraries, and are therefore extensible.
+Libraries called
+.IB /lib/libnss_SERVICE.so. X
+will provide the named
+.IR SERVICE .
+On a standard installation, you can use
+"files", "db", "nis", and "nisplus".
+For the
+.B hosts
+database, you can additionally specify "dns".
+For the
+.BR passwd ,
+.BR group ,
+and
+.B shadow
+databases, you can additionally specify
+"compat" (see
+.B "Compatibility mode"
+below).
+The version number
+.B X
+may be 1 for glibc 2.0, or 2 for glibc 2.1 and later.
+On systems with additional libraries installed, you may have access to
+further services such as "hesiod", "ldap", "winbind", and "wins".
+.P
+An action may also be specified following a service specification.
+The action modifies the behavior following a result obtained
+from the preceding data source.
+Action items take the general form:
+.P
+.RS 4
+.RI [ STATUS = ACTION ]
+.br
+.RI [! STATUS = ACTION ]
+.RE
+.P
+where
+.P
+.RS 4
+.I STATUS
+=>
+.B success
+|
+.B notfound
+|
+.B unavail
+|
+.B tryagain
+.br
+.I ACTION
+=>
+.B return
+|
+.B continue
+|
+.B merge
+.RE
+.P
+The ! negates the test, matching all possible results except the
+one specified.
+The case of the keywords is not significant.
+.P
+The
+.I STATUS
+value is matched against the result of the lookup function called by
+the preceding service specification, and can be one of:
+.RS 4
+.TP 12
+.B success
+No error occurred and the requested entry is returned.
+The default action for this condition is "return".
+.TP
+.B notfound
+The lookup succeeded, but the requested entry was not found.
+The default action for this condition is "continue".
+.TP
+.B unavail
+The service is permanently unavailable.
+This can mean either that the
+required file cannot be read, or, for network services, that the server
+is not available or does not allow queries.
+The default action for this condition is "continue".
+.TP
+.B tryagain
+The service is temporarily unavailable.
+This could mean a file is
+locked or a server currently cannot accept more connections.
+The default action for this condition is "continue".
+.RE
+.P
+The
+.I ACTION
+value can be one of:
+.RS 4
+.TP 12
+.B return
+Return a result now.
+Do not call any further lookup functions.
+However, for compatibility reasons, if this is the selected action for the
+.B group
+database and the
+.B notfound
+status, and the configuration file does not contain the
+.B initgroups
+line, the next lookup function is always called,
+without affecting the search result.
+.TP
+.B continue
+Call the next lookup function.
+.TP
+.B merge
+.I [SUCCESS=merge]
+is used between two database entries.
+When a group is located in the first of the two group entries,
+processing will continue on to the next one.
+If the group is also found in the next entry (and the group name and GID
+are an exact match), the member list of the second entry will be added
+to the group object to be returned.
+Available since glibc 2.24.
+Note that merging will not be done for
+.BR getgrent (3)
+nor will duplicate members be pruned when they occur in both entries
+being merged.
+.RE
+.SS Compatibility mode (compat)
+The NSS "compat" service is similar to "files" except that it
+additionally permits special entries in corresponding files
+for granting users or members of netgroups access to the system.
+The following entries are valid in this mode:
+.RS 4
+.P
+For
+.B passwd
+and
+.B shadow
+databases:
+.RS 4
+.TP 12
+.BI + user
+Include the specified
+.I user
+from the NIS passwd/shadow map.
+.TP
+.BI +@ netgroup
+Include all users in the given
+.IR netgroup .
+.TP
+.BI \- user
+Exclude the specified
+.I user
+from the NIS passwd/shadow map.
+.TP
+.BI \-@ netgroup
+Exclude all users in the given
+.IR netgroup .
+.TP
+.B +
+Include every user, except previously excluded ones, from the
+NIS passwd/shadow map.
+.RE
+.P
+For
+.B group
+database:
+.RS 4
+.TP 12
+.BI + group
+Include the specified
+.I group
+from the NIS group map.
+.TP
+.BI \- group
+Exclude the specified
+.I group
+from the NIS group map.
+.TP
+.B +
+Include every group, except previously excluded ones, from the
+NIS group map.
+.RE
+.RE
+.P
+By default, the source is "nis", but this may be
+overridden by specifying any NSS service except "compat" itself
+as the source for the pseudo-databases
+.BR passwd_compat ,
+.BR group_compat ,
+and
+.BR shadow_compat .
+.SH FILES
+A service named
+.I SERVICE
+is implemented by a shared object library named
+.IB libnss_SERVICE.so. X
+that resides in
+.IR /lib .
+.RS 4
+.TP 25
+.PD 0
+.I /etc/nsswitch.conf
+NSS configuration file.
+.TP
+.IB /lib/libnss_compat.so. X
+implements "compat" source.
+.TP
+.IB /lib/libnss_db.so. X
+implements "db" source.
+.TP
+.IB /lib/libnss_dns.so. X
+implements "dns" source.
+.TP
+.IB /lib/libnss_files.so. X
+implements "files" source.
+.TP
+.IB /lib/libnss_hesiod.so. X
+implements "hesiod" source.
+.TP
+.IB /lib/libnss_nis.so. X
+implements "nis" source.
+.TP
+.IB /lib/libnss_nisplus.so. X
+implements "nisplus" source.
+.PD
+.RE
+.P
+The following files are read when "files" source is specified
+for respective databases:
+.RS 4
+.TP 12
+.PD 0
+.B aliases
+.I /etc/aliases
+.TP
+.B ethers
+.I /etc/ethers
+.TP
+.B group
+.I /etc/group
+.TP
+.B hosts
+.I /etc/hosts
+.TP
+.B initgroups
+.I /etc/group
+.TP
+.B netgroup
+.I /etc/netgroup
+.TP
+.B networks
+.I /etc/networks
+.TP
+.B passwd
+.I /etc/passwd
+.TP
+.B protocols
+.I /etc/protocols
+.TP
+.B publickey
+.I /etc/publickey
+.TP
+.B rpc
+.I /etc/rpc
+.TP
+.B services
+.I /etc/services
+.TP
+.B shadow
+.I /etc/shadow
+.PD
+.RE
+.SH NOTES
+Starting with glibc 2.33,
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=12459
+.B nsswitch.conf
+is automatically reloaded if the file is changed.
+In earlier versions, the entire file was read only once within each process.
+If the file was later changed,
+the process would continue using the old configuration.
+.P
+Traditionally, there was only a single source for service information,
+often in the form of a single configuration
+file (e.g., \fI/etc/passwd\fP).
+However, as other name services, such as the Network Information
+Service (NIS) and the Domain Name Service (DNS), became popular,
+a method was needed
+that would be more flexible than fixed search orders coded into
+the C library.
+The Name Service Switch mechanism,
+which was based on the mechanism used by
+Sun Microsystems in the Solaris 2 C library,
+introduced a cleaner solution to the problem.
+.SH SEE ALSO
+.BR getent (1),
+.BR nss (5)
diff --git a/man/man5/passwd.5 b/man/man5/passwd.5
new file mode 100644
index 000000000..24164cb73
--- /dev/null
+++ b/man/man5/passwd.5
@@ -0,0 +1,160 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sun Jul 25 10:46:28 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Aug 21 18:12:27 1994 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Jun 18 01:53:57 1995 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Mon Jan  5 20:24:40 MET 1998 by Michael Haardt
+.\"  (michael@cantor.informatik.rwth-aachen.de)
+.TH passwd 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+passwd \- password file
+.SH DESCRIPTION
+The
+.I /etc/passwd
+file is a text file that describes user login accounts for the system.
+It should have read permission allowed for all users (many utilities, like
+.BR ls (1)
+use it to map user IDs to usernames), but write access only for the
+superuser.
+.P
+In the good old days there was no great problem with this general
+read permission.
+Everybody could read the encrypted passwords, but the
+hardware was too slow to crack a well-chosen password, and moreover the
+basic assumption used to be that of a friendly user-community.
+These days many people run some version of the shadow password suite, where
+.I /etc/passwd
+has an \[aq]x\[aq] character in the password field,
+and the encrypted passwords are in
+.IR /etc/shadow ,
+which is readable by the superuser only.
+.P
+If the encrypted password, whether in
+.I /etc/passwd
+or in
+.IR /etc/shadow ,
+is an empty string, login is allowed without even asking for a password.
+Note that this functionality may be intentionally disabled in applications,
+or configurable (for example using the
+.RB \[dq] nullok \[dq]
+or
+.RB \[dq] nonull \[dq]
+arguments to
+.BR pam_unix (8)).
+.P
+If the encrypted password in
+.I /etc/passwd
+is "\fI*NP*\fP" (without the quotes),
+the shadow record should be obtained from an NIS+ server.
+.P
+Regardless of whether shadow passwords are used, many system administrators
+use an asterisk (*) in the encrypted password field to make sure
+that this user can not authenticate themself using a
+password.
+(But see NOTES below.)
+.P
+If you create a new login, first put an asterisk (*) in the password field,
+then use
+.BR passwd (1)
+to set it.
+.P
+Each line of the file describes a single user,
+and contains seven colon-separated fields:
+.P
+.in +4n
+.EX
+name:password:UID:GID:GECOS:directory:shell
+.EE
+.in
+.P
+The field are as follows:
+.TP 12
+.I name
+This is the user's login name.
+It should not contain capital letters.
+.TP
+.I password
+This is either the encrypted user password,
+an asterisk (*), or the letter \[aq]x\[aq].
+(See
+.BR pwconv (8)
+for an explanation of \[aq]x\[aq].)
+.TP
+.I UID
+The privileged
+.I root
+login account (superuser) has the user ID 0.
+.TP
+.I GID
+This is the numeric primary group ID for this user.
+(Additional groups for the user are defined in the system group file; see
+.BR group (5)).
+.TP
+.I GECOS
+This field (sometimes called the "comment field")
+is optional and used only for informational purposes.
+Usually, it contains the full username.
+Some programs (for example,
+.BR finger (1))
+display information from this field.
+.IP
+GECOS stands for "General Electric Comprehensive Operating System",
+which was renamed to GCOS when
+GE's large systems division was sold to Honeywell.
+Dennis Ritchie has reported: "Sometimes we sent printer output or
+batch jobs to the GCOS machine.
+The gcos field in the password file was a place to stash the
+information for the $IDENTcard.
+Not elegant."
+.TP
+.I directory
+This is the user's home directory:
+the initial directory where the user is placed after logging in.
+The value in this field is used to set the
+.B HOME
+environment variable.
+.TP
+.I shell
+This is the program to run at login (if empty, use
+.IR /bin/sh ).
+If set to a nonexistent executable, the user will be unable to login
+through
+.BR login (1).
+The value in this field is used to set the
+.B SHELL
+environment variable.
+.SH FILES
+.I /etc/passwd
+.SH NOTES
+If you want to create user groups, there must be an entry in
+.IR /etc/group ,
+or no group will exist.
+.P
+If the encrypted password is set to an asterisk (*), the user will be unable
+to login using
+.BR login (1),
+but may still login using
+.BR rlogin (1),
+run existing processes and initiate new ones through
+.BR rsh (1),
+.BR cron (8),
+.BR at (1),
+or mail filters, etc.
+Trying to lock an account by simply changing the
+shell field yields the same result and additionally allows the use of
+.BR su (1).
+.SH SEE ALSO
+.BR chfn (1),
+.BR chsh (1),
+.BR login (1),
+.BR passwd (1),
+.BR su (1),
+.BR crypt (3),
+.BR getpwent (3),
+.BR getpwnam (3),
+.BR group (5),
+.BR shadow (5),
+.BR vipw (8)
diff --git a/man/man5/proc.5 b/man/man5/proc.5
new file mode 100644
index 000000000..8022ca49e
--- /dev/null
+++ b/man/man5/proc.5
@@ -0,0 +1,261 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+proc \- process information, system information, and sysctl pseudo-filesystem
+.SH DESCRIPTION
+The
+.B proc
+filesystem is a pseudo-filesystem which provides an interface to
+kernel data structures.
+It is commonly mounted at
+.IR /proc .
+Typically, it is mounted automatically by the system,
+but it can also be mounted manually using a command such as:
+.P
+.in +4n
+.EX
+mount \-t proc proc /proc
+.EE
+.in
+.P
+Most of the files in the
+.B proc
+filesystem are read-only,
+but some files are writable, allowing kernel variables to be changed.
+.\"
+.SS Mount options
+The
+.B proc
+filesystem supports the following mount options:
+.TP
+.BR hidepid "=\fIn\fP (since Linux 3.3)"
+.\" commit 0499680a42141d86417a8fbaa8c8db806bea1201
+This option controls who can access the information in
+.IR /proc/ pid
+directories.
+The argument,
+.IR n ,
+is one of the following values:
+.RS
+.TP 4
+0
+Everybody may access all
+.IR /proc/ pid
+directories.
+This is the traditional behavior,
+and the default if this mount option is not specified.
+.TP
+1
+Users may not access files and subdirectories inside any
+.IR /proc/ pid
+directories but their own (the
+.IR /proc/ pid
+directories themselves remain visible).
+Sensitive files such as
+.IR /proc/ pid /cmdline
+and
+.IR /proc/ pid /status
+are now protected against other users.
+This makes it impossible to learn whether any user is running a
+specific program
+(so long as the program doesn't otherwise reveal itself by its behavior).
+.\" As an additional bonus, since
+.\" .IR /proc/[pid]/cmdline
+.\" is inaccessible for other users,
+.\" poorly written programs passing sensitive information via
+.\" program arguments are now protected against local eavesdroppers.
+.TP
+2
+As for mode 1, but in addition the
+.IR /proc/ pid
+directories belonging to other users become invisible.
+This means that
+.IR /proc/ pid
+entries can no longer be used to discover the PIDs on the system.
+This doesn't hide the fact that a process with a specific PID value exists
+(it can be learned by other means, for example, by "kill \-0 $PID"),
+but it hides a process's UID and GID,
+which could otherwise be learned by employing
+.BR stat (2)
+on a
+.IR /proc/ pid
+directory.
+This greatly complicates an attacker's task of gathering
+information about running processes (e.g., discovering whether
+some daemon is running with elevated privileges,
+whether another user is running some sensitive program,
+whether other users are running any program at all, and so on).
+.RE
+.TP
+.BR gid "=\fIgid\fP (since Linux 3.3)"
+.\" commit 0499680a42141d86417a8fbaa8c8db806bea1201
+Specifies the ID of a group whose members are authorized to
+learn process information otherwise prohibited by
+.B hidepid
+(i.e., users in this group behave as though
+.I /proc
+was mounted with
+.IR hidepid=0 ).
+This group should be used instead of approaches such as putting
+nonroot users into the
+.BR sudoers (5)
+file.
+.\"
+.SS Overview
+Underneath
+.IR /proc ,
+there are the following general groups of files and subdirectories:
+.TP
+.IR /proc/ "pid subdirectories"
+Each one of these subdirectories contains files and subdirectories
+exposing information about the process with the corresponding process ID.
+.IP
+Underneath each of the
+.IR /proc/ pid
+directories, a
+.I task
+subdirectory contains subdirectories of the form
+.IR task/ tid,
+which contain corresponding information about each of the threads
+in the process, where
+.I tid
+is the kernel thread ID of the thread.
+.IP
+The
+.IR /proc/ pid
+subdirectories are visible when iterating through
+.I /proc
+with
+.BR getdents (2)
+(and thus are visible when one uses
+.BR ls (1)
+to view the contents of
+.IR /proc ).
+.TP
+.IR /proc/ "tid subdirectories"
+Each one of these subdirectories contains files and subdirectories
+exposing information about the thread with the corresponding thread ID.
+The contents of these directories are the same as the corresponding
+.IR /proc/ pid /task/ tid
+directories.
+.IP
+The
+.IR /proc/ tid
+subdirectories are
+.I not
+visible when iterating through
+.I /proc
+with
+.BR getdents (2)
+(and thus are
+.I not
+visible when one uses
+.BR ls (1)
+to view the contents of
+.IR /proc ).
+.TP
+.I /proc/self
+When a process accesses this magic symbolic link,
+it resolves to the process's own
+.IR /proc/ pid
+directory.
+.TP
+.I /proc/thread\-self
+When a thread accesses this magic symbolic link,
+it resolves to the process's own
+.IR /proc/self/task/ tid
+directory.
+.TP
+.I /proc/[a\-z]*
+Various other files and subdirectories under
+.I /proc
+expose system-wide information.
+.P
+All of the above are described in more detail in separate manpages
+whose names start with
+.BR proc_ .
+.\"
+.\" .SH FILES
+.\" FIXME Describe /proc/[pid]/sessionid
+.\"	  commit 1e0bd7550ea9cf474b1ad4c6ff5729a507f75fdc
+.\"       CONFIG_AUDITSYSCALL
+.\"       Added in Linux 2.6.25; read-only; only readable by real UID
+.\"
+.\" FIXME Describe /proc/[pid]/sched
+.\"       Added in Linux 2.6.23
+.\"       CONFIG_SCHED_DEBUG, and additional fields if CONFIG_SCHEDSTATS
+.\"       Displays various scheduling parameters
+.\"       This file can be written, to reset stats
+.\"       The set of fields exposed by this file have changed
+.\"	  significantly over time.
+.\"       commit 43ae34cb4cd650d1eb4460a8253a8e747ba052ac
+.\"
+.\" FIXME Describe /proc/[pid]/schedstats and
+.\"       /proc/[pid]/task/[tid]/schedstats
+.\"       Added in Linux 2.6.9
+.\"       CONFIG_SCHEDSTATS
+.\" FIXME Document /proc/sched_debug (since Linux 2.6.23)
+.\" See also /proc/[pid]/sched
+.\" FIXME 2.6.13 seems to have /proc/vmcore implemented; document this
+.\" 	See Documentation/kdump/kdump.txt
+.\"	commit 666bfddbe8b8fd4fd44617d6c55193d5ac7edb29
+.\" 	Needs CONFIG_VMCORE
+.\"
+.SH NOTES
+Many files contain strings (e.g., the environment and command line)
+that are in the internal format,
+with subfields terminated by null bytes (\[aq]\e0\[aq]).
+When inspecting such files, you may find that the results are more readable
+if you use a command of the following form to display them:
+.P
+.in +4n
+.EX
+.RB "$" " cat \fIfile\fP | tr \[aq]\e000\[aq] \[aq]\en\[aq]"
+.EE
+.in
+.\" .SH ACKNOWLEDGEMENTS
+.\" The material on /proc/sys/fs and /proc/sys/kernel is closely based on
+.\" kernel source documentation files written by Rik van Riel.
+.SH SEE ALSO
+.BR cat (1),
+.BR dmesg (1),
+.BR find (1),
+.BR free (1),
+.BR htop (1),
+.BR init (1),
+.BR ps (1),
+.BR pstree (1),
+.BR tr (1),
+.BR uptime (1),
+.BR chroot (2),
+.BR mmap (2),
+.BR readlink (2),
+.BR syslog (2),
+.BR slabinfo (5),
+.BR sysfs (5),
+.BR hier (7),
+.BR namespaces (7),
+.BR time (7),
+.BR arp (8),
+.BR hdparm (8),
+.BR ifconfig (8),
+.BR lsmod (8),
+.BR lspci (8),
+.BR mount (8),
+.BR netstat (8),
+.BR procinfo (8),
+.BR route (8),
+.BR sysctl (8)
+.P
+The Linux kernel source files:
+.IR Documentation/filesystems/proc.rst ,
+.IR Documentation/admin\-guide/sysctl/fs.rst ,
+.IR Documentation/admin\-guide/sysctl/kernel.rst ,
+.IR Documentation/admin\-guide/sysctl/net.rst ,
+and
+.IR Documentation/admin\-guide/sysctl/vm.rst .
diff --git a/man/man5/proc_apm.5 b/man/man5/proc_apm.5
new file mode 100644
index 000000000..0f37a6ceb
--- /dev/null
+++ b/man/man5/proc_apm.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_apm 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/apm \- advanced power management
+.SH DESCRIPTION
+.TP
+.I /proc/apm
+Advanced power management version and battery information when
+.B CONFIG_APM
+is defined at kernel compilation time.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_buddyinfo.5 b/man/man5/proc_buddyinfo.5
new file mode 100644
index 000000000..3bdae717e
--- /dev/null
+++ b/man/man5/proc_buddyinfo.5
@@ -0,0 +1,58 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_buddyinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/buddyinfo \- memory fragmentation
+.SH DESCRIPTION
+.TP
+.I /proc/buddyinfo
+This file contains information which is used for diagnosing memory
+fragmentation issues.
+Each line starts with the identification of the node and the name
+of the zone which together identify a memory region.
+This is then
+followed by the count of available chunks of a certain order in
+which these zones are split.
+The size in bytes of a certain order is given by the formula:
+.IP
+.in +4n
+.EX
+(2\[ha]order)\ *\ PAGE_SIZE
+.EE
+.in
+.IP
+The binary buddy allocator algorithm inside the kernel will split
+one chunk into two chunks of a smaller order (thus with half the
+size) or combine two contiguous chunks into one larger chunk of
+a higher order (thus with double the size) to satisfy allocation
+requests and to counter memory fragmentation.
+The order matches the column number, when starting to count at zero.
+.IP
+For example on an x86-64 system:
+.RS -12
+.EX
+Node 0, zone     DMA     1    1    1    0    2    1    1    0    1    1    3
+Node 0, zone   DMA32    65   47    4   81   52   28   13   10    5    1  404
+Node 0, zone  Normal   216   55  189  101   84   38   37   27    5    3  587
+.EE
+.RE
+.IP
+In this example, there is one node containing three zones and there
+are 11 different chunk sizes.
+If the page size is 4 kilobytes, then the first zone called
+.I DMA
+(on x86 the first 16 megabyte of memory) has 1 chunk of 4 kilobytes
+(order 0) available and has 3 chunks of 4 megabytes (order 10) available.
+.IP
+If the memory is heavily fragmented, the counters for higher
+order chunks will be zero and allocation of large contiguous areas
+will fail.
+.IP
+Further information about the zones can be found in
+.IR /proc/zoneinfo .
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_bus.5 b/man/man5/proc_bus.5
new file mode 100644
index 000000000..4797d8eb2
--- /dev/null
+++ b/man/man5/proc_bus.5
@@ -0,0 +1,35 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_bus 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/bus/ \- installed buses
+.SH DESCRIPTION
+.TP
+.I /proc/bus/
+Contains subdirectories for installed buses.
+.TP
+.I /proc/bus/pccard/
+Subdirectory for PCMCIA devices when
+.B CONFIG_PCMCIA
+is set at kernel compilation time.
+.TP
+.I /proc/bus/pccard/drivers
+.TP
+.I /proc/bus/pci/
+Contains various bus subdirectories and pseudo-files containing
+information about PCI buses, installed devices, and device
+drivers.
+Some of these files are not ASCII.
+.TP
+.I /proc/bus/pci/devices
+Information about PCI devices.
+They may be accessed through
+.BR lspci (8)
+and
+.BR setpci (8).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_cgroups.5 b/man/man5/proc_cgroups.5
new file mode 100644
index 000000000..ae418e695
--- /dev/null
+++ b/man/man5/proc_cgroups.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_cgroups 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/cgroups \- control groups
+.SH DESCRIPTION
+.TP
+.IR /proc/cgroups " (since Linux 2.6.24)"
+See
+.BR cgroups (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_cmdline.5 b/man/man5/proc_cmdline.5
new file mode 100644
index 000000000..66f0f8627
--- /dev/null
+++ b/man/man5/proc_cmdline.5
@@ -0,0 +1,22 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_cmdline 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/cmdline \- kernel boot arguments
+.SH DESCRIPTION
+.TP
+.I /proc/cmdline
+Arguments passed to the Linux kernel at boot time.
+Often done via a boot manager such as
+.BR lilo (8)
+or
+.BR grub (8).
+Any arguments embedded in the kernel image or initramfs via
+.B CONFIG_BOOT_CONFIG
+will also be displayed.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_config.gz.5 b/man/man5/proc_config.gz.5
new file mode 100644
index 000000000..2b4654652
--- /dev/null
+++ b/man/man5/proc_config.gz.5
@@ -0,0 +1,40 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_config.gz 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/config.gz \- kernel build configuration
+.SH DESCRIPTION
+.TP
+.IR /proc/config.gz " (since Linux 2.6)"
+This file exposes the configuration options that were used
+to build the currently running kernel,
+in the same format as they would be shown in the
+.I .config
+file that resulted when configuring the kernel (using
+.IR "make xconfig" ,
+.IR "make config" ,
+or similar).
+The file contents are compressed; view or search them using
+.BR zcat (1)
+and
+.BR zgrep (1).
+As long as no changes have been made to the following file,
+the contents of
+.I /proc/config.gz
+are the same as those provided by:
+.IP
+.in +4n
+.EX
+cat /lib/modules/$(uname \-r)/build/.config
+.EE
+.in
+.IP
+.I /proc/config.gz
+is provided only if the kernel is configured with
+.BR CONFIG_IKCONFIG_PROC .
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_cpuinfo.5 b/man/man5/proc_cpuinfo.5
new file mode 100644
index 000000000..f79e971d1
--- /dev/null
+++ b/man/man5/proc_cpuinfo.5
@@ -0,0 +1,24 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_cpuinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/cpuinfo \- CPU and system architecture information
+.SH DESCRIPTION
+.TP
+.I /proc/cpuinfo
+This is a collection of CPU and system architecture dependent items,
+for each supported architecture a different list.
+Two common entries are \fIprocessor\fP which gives CPU number and
+\fIbogomips\fP; a system constant that is calculated
+during kernel initialization.
+SMP machines have information for
+each CPU.
+The
+.BR lscpu (1)
+command gathers its information from this file.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_crypto.5 b/man/man5/proc_crypto.5
new file mode 100644
index 000000000..bca620301
--- /dev/null
+++ b/man/man5/proc_crypto.5
@@ -0,0 +1,26 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_crypto 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/crypto \- ciphers provided by kernel crypto API
+.SH DESCRIPTION
+.TP
+.I /proc/crypto
+A list of the ciphers provided by the kernel crypto API.
+For details, see the kernel
+.I "Linux Kernel Crypto API"
+documentation available under the kernel source directory
+.I Documentation/crypto/
+.\" commit 3b72c814a8e8cd638e1ba0da4dfce501e9dff5af
+(or
+.I Documentation/DocBook
+before Linux 4.10;
+the documentation can be built using a command such as
+.I make htmldocs
+in the root directory of the kernel source tree).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_devices.5 b/man/man5/proc_devices.5
new file mode 100644
index 000000000..de346f510
--- /dev/null
+++ b/man/man5/proc_devices.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_devices 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/devices \- major numbers and device groups
+.SH DESCRIPTION
+.TP
+.I /proc/devices
+Text listing of major numbers and device groups.
+This can be used by MAKEDEV scripts for consistency with the kernel.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_diskstats.5 b/man/man5/proc_diskstats.5
new file mode 100644
index 000000000..15d5c6374
--- /dev/null
+++ b/man/man5/proc_diskstats.5
@@ -0,0 +1,21 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_diskstats 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/diskstats \- disk I/O statistics
+.SH DESCRIPTION
+.TP
+.IR /proc/diskstats " (since Linux 2.5.69)"
+This file contains disk I/O statistics for each disk device.
+See the Linux kernel source file
+.I Documentation/admin\-guide/iostats.rst
+(or
+.I Documentation/iostats.txt
+before Linux 5.3)
+for further information.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_dma.5 b/man/man5/proc_dma.5
new file mode 100644
index 000000000..7f8dda47c
--- /dev/null
+++ b/man/man5/proc_dma.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_dma 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/dma \- ISA DMA channels
+.SH DESCRIPTION
+.TP
+.I /proc/dma
+This is a list of the registered \fIISA\fP DMA (direct memory access)
+channels in use.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_driver.5 b/man/man5/proc_driver.5
new file mode 100644
index 000000000..014fce113
--- /dev/null
+++ b/man/man5/proc_driver.5
@@ -0,0 +1,15 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_driver 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/driver/ \- empty dir
+.SH DESCRIPTION
+.TP
+.I /proc/driver/
+Empty subdirectory.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_execdomains.5 b/man/man5/proc_execdomains.5
new file mode 100644
index 000000000..aab78ed66
--- /dev/null
+++ b/man/man5/proc_execdomains.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_execdomains 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/execdomains \- ABI personalities (obsolete)
+.SH DESCRIPTION
+.TP
+.I /proc/execdomains
+Used to list ABI personalities before Linux 4.1;
+now contains a constant string for userspace compatibility.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_fb.5 b/man/man5/proc_fb.5
new file mode 100644
index 000000000..b17a9c309
--- /dev/null
+++ b/man/man5/proc_fb.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_fb 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/fb \- frame buffer
+.SH DESCRIPTION
+.TP
+.I /proc/fb
+Frame buffer information when
+.B CONFIG_FB
+is defined during kernel compilation.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_filesystems.5 b/man/man5/proc_filesystems.5
new file mode 100644
index 000000000..57fd9b966
--- /dev/null
+++ b/man/man5/proc_filesystems.5
@@ -0,0 +1,33 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.\" FIXME cross check against Documentation/filesystems/proc.txt
+.\" to see what information could be imported from that file
+.\" into this file.
+.\"
+.TH proc_filesystems 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/filesystems \- supported filesystems
+.SH DESCRIPTION
+.TP
+.I /proc/filesystems
+A text listing of the filesystems which are supported by the kernel,
+namely filesystems which were compiled into the kernel or whose kernel
+modules are currently loaded.
+(See also
+.BR filesystems (5).)
+If a filesystem is marked with "nodev",
+this means that it does not require a block device to be mounted
+(e.g., virtual filesystem, network filesystem).
+.IP
+Incidentally, this file may be used by
+.BR mount (8)
+when no filesystem is specified and it didn't manage to determine the
+filesystem type.
+Then filesystems contained in this file are tried
+(excepted those that are marked with "nodev").
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_fs.5 b/man/man5/proc_fs.5
new file mode 100644
index 000000000..d24e3e3c2
--- /dev/null
+++ b/man/man5/proc_fs.5
@@ -0,0 +1,18 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_fs 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/fs/ \- mounted filesystems
+.SH DESCRIPTION
+.TP
+.I /proc/fs/
+.\" FIXME Much more needs to be said about /proc/fs
+.\"
+Contains subdirectories that in turn contain files
+with information about (certain) mounted filesystems.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_ide.5 b/man/man5/proc_ide.5
new file mode 100644
index 000000000..f87a6e8a4
--- /dev/null
+++ b/man/man5/proc_ide.5
@@ -0,0 +1,37 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_ide 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/ide/ \- IDE channels and attached devices
+.SH DESCRIPTION
+.TP
+.I /proc/ide
+This directory
+exists on systems with the IDE bus.
+There are directories for each IDE channel and attached device.
+Files include:
+.IP
+.in +4n
+.EX
+cache              buffer size in KB
+capacity           number of sectors
+driver             driver version
+geometry           physical and logical geometry
+identify           in hexadecimal
+media              media type
+model              manufacturer\[aq]s model number
+settings           drive settings
+smart_thresholds   IDE disk management thresholds (in hex)
+smart_values       IDE disk management values (in hex)
+.EE
+.in
+.IP
+The
+.BR hdparm (8)
+utility provides access to this information in a friendly format.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_interrupts.5 b/man/man5/proc_interrupts.5
new file mode 100644
index 000000000..c8bda0a70
--- /dev/null
+++ b/man/man5/proc_interrupts.5
@@ -0,0 +1,22 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_interrupts 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/interrupts \- number of interrupts
+.SH DESCRIPTION
+.TP
+.I /proc/interrupts
+This is used to record the number of interrupts per CPU per IO device.
+Since Linux 2.6.24,
+for the i386 and x86-64 architectures, at least, this also includes
+interrupts internal to the system (that is, not associated with a device
+as such), such as NMI (nonmaskable interrupt), LOC (local timer interrupt),
+and for SMP systems, TLB (TLB flush interrupt), RES (rescheduling
+interrupt), CAL (remote function call interrupt), and possibly others.
+Very easy to read formatting, done in ASCII.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_iomem.5 b/man/man5/proc_iomem.5
new file mode 100644
index 000000000..b6fbb4b1d
--- /dev/null
+++ b/man/man5/proc_iomem.5
@@ -0,0 +1,15 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_iomem 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/iomem \- I/O memory map
+.SH DESCRIPTION
+.TP
+.I /proc/iomem
+I/O memory map in Linux 2.4.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_ioports.5 b/man/man5/proc_ioports.5
new file mode 100644
index 000000000..f6cc16b08
--- /dev/null
+++ b/man/man5/proc_ioports.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_ioports 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/ioports \- I/O port regions
+.SH DESCRIPTION
+.TP
+.I /proc/ioports
+This is a list of currently registered Input-Output port regions that
+are in use.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_kallsyms.5 b/man/man5/proc_kallsyms.5
new file mode 100644
index 000000000..bc7ffd592
--- /dev/null
+++ b/man/man5/proc_kallsyms.5
@@ -0,0 +1,25 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_kallsyms 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/kallsyms \- kernel exported symbols
+.SH DESCRIPTION
+.TP
+.IR /proc/kallsyms " (since Linux 2.5.71)"
+This holds the kernel exported symbol definitions used by the
+.BR modules (X)
+tools to dynamically link and bind loadable modules.
+In Linux 2.5.47 and earlier, a similar file with slightly different syntax
+was named
+.IR ksyms .
+.SH HISTORY
+.TP
+.IR /proc/ksyms " (Linux 1.1.23\[en]2.5.47)"
+See
+.IR /proc/kallsyms .
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_kcore.5 b/man/man5/proc_kcore.5
new file mode 100644
index 000000000..8848c6458
--- /dev/null
+++ b/man/man5/proc_kcore.5
@@ -0,0 +1,24 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_kcore 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/kcore \- physical memory
+.SH DESCRIPTION
+.TP
+.I /proc/kcore
+This file represents the physical memory of the system and is stored
+in the ELF core file format.
+With this pseudo-file, and an unstripped
+kernel
+.RI ( /usr/src/linux/vmlinux )
+binary, GDB can be used to
+examine the current state of any kernel data structures.
+.IP
+The total length of the file is the size of physical memory (RAM) plus
+4\ KiB.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_key-users.5 b/man/man5/proc_key-users.5
new file mode 100644
index 000000000..7f88ac3ac
--- /dev/null
+++ b/man/man5/proc_key-users.5
@@ -0,0 +1 @@
+.so man5/proc_keys.5
diff --git a/man/man5/proc_keys.5 b/man/man5/proc_keys.5
new file mode 100644
index 000000000..b1f74b4b2
--- /dev/null
+++ b/man/man5/proc_keys.5
@@ -0,0 +1,20 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_keys 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/keys, /proc/key\-users \- in-kernel key management
+.SH DESCRIPTION
+.TP
+.IR /proc/keys " (since Linux 2.6.10)"
+See
+.BR keyrings (7).
+.TP
+.IR /proc/key\-users " (since Linux 2.6.10)"
+See
+.BR keyrings (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_kmsg.5 b/man/man5/proc_kmsg.5
new file mode 100644
index 000000000..2793907d7
--- /dev/null
+++ b/man/man5/proc_kmsg.5
@@ -0,0 +1,28 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_kmsg 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/kmsg \- kernel messages
+.SH DESCRIPTION
+.TP
+.I /proc/kmsg
+This file can be used instead of the
+.BR syslog (2)
+system call to read kernel messages.
+A process must have superuser
+privileges to read this file, and only one process should read this
+file.
+This file should not be read if a syslog process is running
+which uses the
+.BR syslog (2)
+system call facility to log kernel messages.
+.IP
+Information in this file is retrieved with the
+.BR dmesg (1)
+program.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_kpagecgroup.5 b/man/man5/proc_kpagecgroup.5
new file mode 100644
index 000000000..1cfbf49aa
--- /dev/null
+++ b/man/man5/proc_kpagecgroup.5
@@ -0,0 +1,25 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_kpagecgroup 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/kpagecgroup \- memory cgroups
+.SH DESCRIPTION
+.TP
+.IR /proc/kpagecgroup " (since Linux 4.3)"
+.\" commit 80ae2fdceba8313b0433f899bdd9c6c463291a17
+This file contains a 64-bit inode number of
+the memory cgroup each page is charged to,
+indexed by page frame number (see the discussion of
+.IR /proc/ pid /pagemap ).
+.IP
+The
+.I /proc/kpagecgroup
+file is present only if the
+.B CONFIG_MEMCG
+kernel configuration option is enabled.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_kpagecount.5 b/man/man5/proc_kpagecount.5
new file mode 100644
index 000000000..27a774599
--- /dev/null
+++ b/man/man5/proc_kpagecount.5
@@ -0,0 +1,24 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_kpagecount 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/kpagecount \- count of mappings of physical pages
+.SH DESCRIPTION
+.TP
+.IR /proc/kpagecount " (since Linux 2.6.25)"
+This file contains a 64-bit count of the number of
+times each physical page frame is mapped,
+indexed by page frame number (see the discussion of
+.IR /proc/ pid /pagemap ).
+.IP
+The
+.I /proc/kpagecount
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_kpageflags.5 b/man/man5/proc_kpageflags.5
new file mode 100644
index 000000000..bb43fb79e
--- /dev/null
+++ b/man/man5/proc_kpageflags.5
@@ -0,0 +1,75 @@
+'\" t
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_kpageflags 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/kpageflags \- physical pages frame masks
+.SH DESCRIPTION
+.TP
+.IR /proc/kpageflags " (since Linux 2.6.25)"
+This file contains 64-bit masks corresponding to each physical page frame;
+it is indexed by page frame number (see the discussion of
+.IR /proc/ pid /pagemap ).
+The bits are as follows:
+.RS
+.IP
+.TS
+r l l l.
+0	-	KPF_LOCKED
+1	-	KPF_ERROR
+2	-	KPF_REFERENCED
+3	-	KPF_UPTODATE
+4	-	KPF_DIRTY
+5	-	KPF_LRU
+6	-	KPF_ACTIVE
+7	-	KPF_SLAB
+8	-	KPF_WRITEBACK
+9	-	KPF_RECLAIM
+10	-	KPF_BUDDY
+11	-	KPF_MMAP	(since Linux 2.6.31)
+12	-	KPF_ANON	(since Linux 2.6.31)
+13	-	KPF_SWAPCACHE	(since Linux 2.6.31)
+14	-	KPF_SWAPBACKED	(since Linux 2.6.31)
+15	-	KPF_COMPOUND_HEAD	(since Linux 2.6.31)
+16	-	KPF_COMPOUND_TAIL	(since Linux 2.6.31)
+17	-	KPF_HUGE	(since Linux 2.6.31)
+18	-	KPF_UNEVICTABLE	(since Linux 2.6.31)
+19	-	KPF_HWPOISON	(since Linux 2.6.31)
+20	-	KPF_NOPAGE	(since Linux 2.6.31)
+21	-	KPF_KSM	(since Linux 2.6.32)
+22	-	KPF_THP	(since Linux 3.4)
+23	-	KPF_BALLOON	(since Linux 3.18)
+.\" KPF_BALLOON: commit 09316c09dde33aae14f34489d9e3d243ec0d5938
+24	-	KPF_ZERO_PAGE	(since Linux 4.0)
+.\" KPF_ZERO_PAGE: commit 56873f43abdcd574b25105867a990f067747b2f4
+25	-	KPF_IDLE	(since Linux 4.3)
+.\" KPF_IDLE: commit f074a8f49eb87cde95ac9d040ad5e7ea4f029738
+26	-	KPF_PGTABLE	(since Linux 4.18)
+.\" KPF_PGTABLE: commit 1d40a5ea01d53251c23c7be541d3f4a656cfc537
+.TE
+.RE
+.IP
+For further details on the meanings of these bits,
+see the kernel source file
+.IR Documentation/admin\-guide/mm/pagemap.rst .
+Before Linux 2.6.29,
+.\" commit ad3bdefe877afb47480418fdb05ecd42842de65e
+.\" commit e07a4b9217d1e97d2f3a62b6b070efdc61212110
+.BR KPF_WRITEBACK ,
+.BR KPF_RECLAIM ,
+.BR KPF_BUDDY ,
+and
+.B KPF_LOCKED
+did not report correctly.
+.IP
+The
+.I /proc/kpageflags
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_ksyms.5 b/man/man5/proc_ksyms.5
new file mode 100644
index 000000000..e4fc2a126
--- /dev/null
+++ b/man/man5/proc_ksyms.5
@@ -0,0 +1 @@
+.so man5/proc_kallsyms.5
diff --git a/man/man5/proc_loadavg.5 b/man/man5/proc_loadavg.5
new file mode 100644
index 000000000..eff023b27
--- /dev/null
+++ b/man/man5/proc_loadavg.5
@@ -0,0 +1,27 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_loadavg 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/loadavg \- load average
+.SH DESCRIPTION
+.TP
+.I /proc/loadavg
+The first three fields in this file are load average figures
+giving the number of jobs in the run queue (state R)
+or waiting for disk I/O (state D) averaged over 1, 5, and 15 minutes.
+They are the same as the load average numbers given by
+.BR uptime (1)
+and other programs.
+The fourth field consists of two numbers separated by a slash (/).
+The first of these is the number of currently runnable kernel
+scheduling entities (processes, threads).
+The value after the slash is the number of kernel scheduling entities
+that currently exist on the system.
+The fifth field is the PID of the process that was most
+recently created on the system.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_locks.5 b/man/man5/proc_locks.5
new file mode 100644
index 000000000..63ea8c766
--- /dev/null
+++ b/man/man5/proc_locks.5
@@ -0,0 +1,122 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_locks 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/locks \- current file locks and leases
+.SH DESCRIPTION
+.TP
+.I /proc/locks
+This file shows current file locks
+(\c
+.BR flock (2)
+and
+.BR fcntl (2))
+and leases
+(\c
+.BR fcntl (2)).
+.IP
+An example of the content shown in this file is the following:
+.IP
+.in +4n
+.EX
+1: POSIX  ADVISORY  READ  5433 08:01:7864448 128 128
+2: FLOCK  ADVISORY  WRITE 2001 08:01:7864554 0 EOF
+3: FLOCK  ADVISORY  WRITE 1568 00:2f:32388 0 EOF
+4: POSIX  ADVISORY  WRITE 699 00:16:28457 0 EOF
+5: POSIX  ADVISORY  WRITE 764 00:16:21448 0 0
+6: POSIX  ADVISORY  READ  3548 08:01:7867240 1 1
+7: POSIX  ADVISORY  READ  3548 08:01:7865567 1826 2335
+8: OFDLCK ADVISORY  WRITE \-1 08:01:8713209 128 191
+.EE
+.in
+.IP
+The fields shown in each line are as follows:
+.RS
+.IP [1] 5
+The ordinal position of the lock in the list.
+.IP [2]
+The lock type.
+Values that may appear here include:
+.RS
+.TP
+.B FLOCK
+This is a BSD file lock created using
+.BR flock (2).
+.TP
+.B OFDLCK
+This is an open file description (OFD) lock created using
+.BR fcntl (2).
+.TP
+.B POSIX
+This is a POSIX byte-range lock created using
+.BR fcntl (2).
+.RE
+.IP [3]
+Among the strings that can appear here are the following:
+.RS
+.TP
+.B ADVISORY
+This is an advisory lock.
+.TP
+.B MANDATORY
+This is a mandatory lock.
+.RE
+.IP [4]
+The type of lock.
+Values that can appear here are:
+.RS
+.TP
+.B READ
+This is a POSIX or OFD read lock, or a BSD shared lock.
+.TP
+.B WRITE
+This is a POSIX or OFD write lock, or a BSD exclusive lock.
+.RE
+.IP [5]
+The PID of the process that owns the lock.
+.IP
+Because OFD locks are not owned by a single process
+(since multiple processes may have file descriptors that
+refer to the same open file description),
+the value \-1 is displayed in this field for OFD locks.
+(Before Linux 4.14,
+.\" commit 9d5b86ac13c573795525ecac6ed2db39ab23e2a8
+a bug meant that the PID of the process that
+initially acquired the lock was displayed instead of the value \-1.)
+.IP [6]
+Three colon-separated subfields that identify the major and minor device
+ID of the device containing the filesystem where the locked file resides,
+followed by the inode number of the locked file.
+.IP [7]
+The byte offset of the first byte of the lock.
+For BSD locks, this value is always 0.
+.IP [8]
+The byte offset of the last byte of the lock.
+.B EOF
+in this field means that the lock extends to the end of the file.
+For BSD locks, the value shown is always
+.IR EOF .
+.RE
+.IP
+Since Linux 4.9,
+.\" commit d67fd44f697dff293d7cdc29af929241b669affe
+the list of locks shown in
+.I /proc/locks
+is filtered to show just the locks for the processes in the PID
+namespace (see
+.BR pid_namespaces (7))
+for which the
+.I /proc
+filesystem was mounted.
+(In the initial PID namespace,
+there is no filtering of the records shown in this file.)
+.IP
+The
+.BR lslocks (8)
+command provides a bit more information about each lock.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_malloc.5 b/man/man5/proc_malloc.5
new file mode 100644
index 000000000..36c13bf86
--- /dev/null
+++ b/man/man5/proc_malloc.5
@@ -0,0 +1,18 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_malloc 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/malloc \- debug malloc (obsolete)
+.SH DESCRIPTION
+.TP
+.IR /proc/malloc " (only up to and including Linux 2.2)"
+.\" It looks like this only ever did something back in 1.0 days
+This file is present only if
+.B CONFIG_DEBUG_MALLOC
+was defined during compilation.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_meminfo.5 b/man/man5/proc_meminfo.5
new file mode 100644
index 000000000..4119a1e5c
--- /dev/null
+++ b/man/man5/proc_meminfo.5
@@ -0,0 +1,327 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_meminfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/meminfo \- memory usage
+.SH DESCRIPTION
+.TP
+.I /proc/meminfo
+This file reports statistics about memory usage on the system.
+It is used by
+.BR free (1)
+to report the amount of free and used memory (both physical and swap)
+on the system as well as the shared memory and buffers used by the
+kernel.
+Each line of the file consists of a parameter name, followed by a colon,
+the value of the parameter, and an option unit of measurement (e.g., "kB").
+The list below describes the parameter names and
+the format specifier required to read the field value.
+Except as noted below,
+all of the fields have been present since at least Linux 2.6.0.
+Some fields are displayed only if the kernel was configured
+with various options; those dependencies are noted in the list.
+.RS
+.TP
+.IR MemTotal " %lu"
+Total usable RAM (i.e., physical RAM minus a few reserved
+bits and the kernel binary code).
+.TP
+.IR MemFree " %lu"
+The sum of
+.IR LowFree + HighFree .
+.TP
+.IR MemAvailable " %lu (since Linux 3.14)"
+An estimate of how much memory is available for starting new
+applications, without swapping.
+.TP
+.IR Buffers " %lu"
+Relatively temporary storage for raw disk blocks that
+shouldn't get tremendously large (20 MB or so).
+.TP
+.IR Cached " %lu"
+In-memory cache for files read from the disk (the page cache).
+Doesn't include
+.IR SwapCached .
+.TP
+.IR SwapCached " %lu"
+Memory that once was swapped out, is swapped back in but
+still also is in the swap file.
+(If memory pressure is high, these pages
+don't need to be swapped out again because they are already
+in the swap file.
+This saves I/O.)
+.TP
+.IR Active " %lu"
+Memory that has been used more recently and usually not
+reclaimed unless absolutely necessary.
+.TP
+.IR Inactive " %lu"
+Memory which has been less recently used.
+It is more eligible to be reclaimed for other purposes.
+.TP
+.IR Active(anon) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Inactive(anon) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Active(file) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Inactive(file) " %lu (since Linux 2.6.28)"
+[To be documented.]
+.TP
+.IR Unevictable " %lu (since Linux 2.6.28)"
+(From Linux 2.6.28 to Linux 2.6.30,
+\fBCONFIG_UNEVICTABLE_LRU\fP was required.)
+[To be documented.]
+.TP
+.IR Mlocked " %lu (since Linux 2.6.28)"
+(From Linux 2.6.28 to Linux 2.6.30,
+\fBCONFIG_UNEVICTABLE_LRU\fP was required.)
+[To be documented.]
+.TP
+.IR HighTotal " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Total amount of highmem.
+Highmem is all memory above \[ti]860 MB of physical memory.
+Highmem areas are for use by user-space programs,
+or for the page cache.
+The kernel must use tricks to access
+this memory, making it slower to access than lowmem.
+.TP
+.IR HighFree " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Amount of free highmem.
+.TP
+.IR LowTotal " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Total amount of lowmem.
+Lowmem is memory which can be used for everything that
+highmem can be used for, but it is also available for the
+kernel's use for its own data structures.
+Among many other things,
+it is where everything from
+.I Slab
+is allocated.
+Bad things happen when you're out of lowmem.
+.TP
+.IR LowFree " %lu"
+(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.)
+Amount of free lowmem.
+.TP
+.IR MmapCopy " %lu (since Linux 2.6.29)"
+.RB ( CONFIG_MMU
+is required.)
+[To be documented.]
+.TP
+.IR SwapTotal " %lu"
+Total amount of swap space available.
+.TP
+.IR SwapFree " %lu"
+Amount of swap space that is currently unused.
+.TP
+.IR Dirty " %lu"
+Memory which is waiting to get written back to the disk.
+.TP
+.IR Writeback " %lu"
+Memory which is actively being written back to the disk.
+.TP
+.IR AnonPages " %lu (since Linux 2.6.18)"
+Non-file backed pages mapped into user-space page tables.
+.TP
+.IR Mapped " %lu"
+Files which have been mapped into memory (with
+.BR mmap (2)),
+such as libraries.
+.TP
+.IR Shmem " %lu (since Linux 2.6.32)"
+Amount of memory consumed in
+.BR tmpfs (5)
+filesystems.
+.TP
+.IR KReclaimable " %lu (since Linux 4.20)"
+Kernel allocations that the kernel will attempt to reclaim
+under memory pressure.
+Includes
+.I SReclaimable
+(below), and other direct allocations with a shrinker.
+.TP
+.IR Slab " %lu"
+In-kernel data structures cache.
+(See
+.BR slabinfo (5).)
+.TP
+.IR SReclaimable " %lu (since Linux 2.6.19)"
+Part of
+.IR Slab ,
+that might be reclaimed, such as caches.
+.TP
+.IR SUnreclaim " %lu (since Linux 2.6.19)"
+Part of
+.IR Slab ,
+that cannot be reclaimed on memory pressure.
+.TP
+.IR KernelStack " %lu (since Linux 2.6.32)"
+Amount of memory allocated to kernel stacks.
+.TP
+.IR PageTables " %lu (since Linux 2.6.18)"
+Amount of memory dedicated to the lowest level of page tables.
+.TP
+.IR Quicklists " %lu (since Linux 2.6.27)"
+(\fBCONFIG_QUICKLIST\fP is required.)
+[To be documented.]
+.TP
+.IR NFS_Unstable " %lu (since Linux 2.6.18)"
+NFS pages sent to the server, but not yet committed to stable storage.
+.TP
+.IR Bounce " %lu (since Linux 2.6.18)"
+Memory used for block device "bounce buffers".
+.TP
+.IR WritebackTmp " %lu (since Linux 2.6.26)"
+Memory used by FUSE for temporary writeback buffers.
+.TP
+.IR CommitLimit " %lu (since Linux 2.6.10)"
+This is the total amount of memory currently available to
+be allocated on the system, expressed in kilobytes.
+This limit is adhered to
+only if strict overcommit accounting is enabled (mode 2 in
+.IR /proc/sys/vm/overcommit_memory ).
+The limit is calculated according to the formula described under
+.IR /proc/sys/vm/overcommit_memory .
+For further details, see the kernel source file
+.IR Documentation/vm/overcommit\-accounting.rst .
+.TP
+.IR Committed_AS " %lu"
+The amount of memory presently allocated on the system.
+The committed memory is a sum of all of the memory which
+has been allocated by processes, even if it has not been
+"used" by them as of yet.
+A process which allocates 1 GB of memory (using
+.BR malloc (3)
+or similar), but touches only 300 MB of that memory will show up
+as using only 300 MB of memory even if it has the address space
+allocated for the entire 1 GB.
+.IP
+This 1 GB is memory which has been "committed" to by the VM
+and can be used at any time by the allocating application.
+With strict overcommit enabled on the system (mode 2 in
+.IR /proc/sys/vm/overcommit_memory ),
+allocations which would exceed the
+.I CommitLimit
+will not be permitted.
+This is useful if one needs to guarantee that processes will not
+fail due to lack of memory once that memory has been successfully allocated.
+.TP
+.IR VmallocTotal " %lu"
+Total size of vmalloc memory area.
+.TP
+.IR VmallocUsed " %lu"
+Amount of vmalloc area which is used.
+Since Linux 4.4,
+.\" commit a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0
+this field is no longer calculated, and is hard coded as 0.
+See
+.IR /proc/vmallocinfo .
+.TP
+.IR VmallocChunk " %lu"
+Largest contiguous block of vmalloc area which is free.
+Since Linux 4.4,
+.\" commit a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0
+this field is no longer calculated and is hard coded as 0.
+See
+.IR /proc/vmallocinfo .
+.TP
+.IR HardwareCorrupted " %lu (since Linux 2.6.32)"
+(\fBCONFIG_MEMORY_FAILURE\fP is required.)
+[To be documented.]
+.TP
+.IR LazyFree " %lu (since Linux 4.12)"
+Shows the amount of memory marked by
+.BR madvise (2)
+.BR MADV_FREE .
+.TP
+.IR AnonHugePages " %lu (since Linux 2.6.38)"
+(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.)
+Non-file backed huge pages mapped into user-space page tables.
+.TP
+.IR ShmemHugePages " %lu (since Linux 4.8)"
+(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.)
+Memory used by shared memory (shmem) and
+.BR tmpfs (5)
+allocated with huge pages.
+.TP
+.IR ShmemPmdMapped " %lu (since Linux 4.8)"
+(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.)
+Shared memory mapped into user space with huge pages.
+.TP
+.IR CmaTotal " %lu (since Linux 3.1)"
+Total CMA (Contiguous Memory Allocator) pages.
+(\fBCONFIG_CMA\fP is required.)
+.TP
+.IR CmaFree " %lu (since Linux 3.1)"
+Free CMA (Contiguous Memory Allocator) pages.
+(\fBCONFIG_CMA\fP is required.)
+.TP
+.IR HugePages_Total " %lu"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+The size of the pool of huge pages.
+.TP
+.IR HugePages_Free " %lu"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+The number of huge pages in the pool that are not yet allocated.
+.TP
+.IR HugePages_Rsvd " %lu (since Linux 2.6.17)"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+This is the number of huge pages for
+which a commitment to allocate from the pool has been made,
+but no allocation has yet been made.
+These reserved huge pages
+guarantee that an application will be able to allocate a
+huge page from the pool of huge pages at fault time.
+.TP
+.IR HugePages_Surp " %lu (since Linux 2.6.24)"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+This is the number of huge pages in
+the pool above the value in
+.IR /proc/sys/vm/nr_hugepages .
+The maximum number of surplus huge pages is controlled by
+.IR /proc/sys/vm/nr_overcommit_hugepages .
+.TP
+.IR Hugepagesize " %lu"
+(\fBCONFIG_HUGETLB_PAGE\fP is required.)
+The size of huge pages.
+.TP
+.IR DirectMap4k " %lu (since Linux 2.6.27)"
+Number of bytes of RAM linearly mapped by kernel in 4 kB pages.
+(x86.)
+.TP
+.IR DirectMap4M " %lu (since Linux 2.6.27)"
+Number of bytes of RAM linearly mapped by kernel in 4 MB pages.
+(x86 with
+.B CONFIG_X86_64
+or
+.B CONFIG_X86_PAE
+enabled.)
+.TP
+.IR DirectMap2M " %lu (since Linux 2.6.27)"
+Number of bytes of RAM linearly mapped by kernel in 2 MB pages.
+(x86 with neither
+.B CONFIG_X86_64
+nor
+.B CONFIG_X86_PAE
+enabled.)
+.TP
+.IR DirectMap1G " %lu (since Linux 2.6.27)"
+(x86 with
+.B CONFIG_X86_64
+and
+.B CONFIG_X86_DIRECT_GBPAGES
+enabled.)
+.RE
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_modules.5 b/man/man5/proc_modules.5
new file mode 100644
index 000000000..76491b6d4
--- /dev/null
+++ b/man/man5/proc_modules.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_modules 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/modules \- loaded modules
+.SH DESCRIPTION
+.TP
+.I /proc/modules
+A text list of the modules that have been loaded by the system.
+See also
+.BR lsmod (8).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_mounts.5 b/man/man5/proc_mounts.5
new file mode 100644
index 000000000..7da5a66b9
--- /dev/null
+++ b/man/man5/proc_mounts.5
@@ -0,0 +1 @@
+.so man5/proc_pid_mounts.5
diff --git a/man/man5/proc_mtrr.5 b/man/man5/proc_mtrr.5
new file mode 100644
index 000000000..d4f5e9ab2
--- /dev/null
+++ b/man/man5/proc_mtrr.5
@@ -0,0 +1,24 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_mtrr 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/mtrr \- memory type range registers
+.SH DESCRIPTION
+.TP
+.I /proc/mtrr
+Memory Type Range Registers.
+See the Linux kernel source file
+.I Documentation/x86/mtrr.rst
+(or
+.I Documentation/x86/mtrr.txt
+.\" commit 7225e75144b9718cbbe1820d9c011c809d5773fd
+before Linux 5.2, or
+.I Documentation/mtrr.txt
+before Linux 2.6.28)
+for details.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_net.5 b/man/man5/proc_net.5
new file mode 100644
index 000000000..85a0dbd08
--- /dev/null
+++ b/man/man5/proc_net.5
@@ -0,0 +1 @@
+.so man5/proc_pid_net.5
diff --git a/man/man5/proc_partitions.5 b/man/man5/proc_partitions.5
new file mode 100644
index 000000000..d4f544049
--- /dev/null
+++ b/man/man5/proc_partitions.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_partitions 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/partitions \- major and minor numbers of partitions
+.SH DESCRIPTION
+.TP
+.I /proc/partitions
+Contains the major and minor numbers of each partition as well as the number
+of 1024-byte blocks and the partition name.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pci.5 b/man/man5/proc_pci.5
new file mode 100644
index 000000000..b4a8be5e2
--- /dev/null
+++ b/man/man5/proc_pci.5
@@ -0,0 +1,28 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pci 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pci \- PCI devices
+.SH DESCRIPTION
+.TP
+.I /proc/pci
+This is a listing of all PCI devices found during kernel initialization
+and their configuration.
+.IP
+This file has been deprecated in favor of a new
+.I /proc
+interface for PCI
+.RI ( /proc/bus/pci ).
+It became optional in Linux 2.2 (available with
+.B CONFIG_PCI_OLD_PROC
+set at kernel compilation).
+It became once more nonoptionally enabled in Linux 2.4.
+Next, it was deprecated in Linux 2.6 (still available with
+.B CONFIG_PCI_LEGACY_PROC
+set), and finally removed altogether since Linux 2.6.17.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid.5 b/man/man5/proc_pid.5
new file mode 100644
index 000000000..16c1a3c15
--- /dev/null
+++ b/man/man5/proc_pid.5
@@ -0,0 +1,73 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/, /proc/self/ \- process information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /
+There is a numerical subdirectory for each running process; the
+subdirectory is named by the process ID.
+Each
+.IR /proc/ pid
+subdirectory contains the pseudo-files and directories described below.
+.IP
+The files inside each
+.IR /proc/ pid
+directory are normally owned by the effective user and
+effective group ID of the process.
+However, as a security measure, the ownership is made
+.I root:root
+if the process's "dumpable" attribute is set to a value other than 1.
+.IP
+Before Linux 4.11,
+.\" commit 68eb94f16227336a5773b83ecfa8290f1d6b78ce
+.I root:root
+meant the "global" root user ID and group ID
+(i.e., UID 0 and GID 0 in the initial user namespace).
+Since Linux 4.11,
+if the process is in a noninitial user namespace that has a
+valid mapping for user (group) ID 0 inside the namespace, then
+the user (group) ownership of the files under
+.IR /proc/ pid
+is instead made the same as the root user (group) ID of the namespace.
+This means that inside a container,
+things work as expected for the container "root" user.
+.IP
+The process's "dumpable" attribute may change for the following reasons:
+.RS
+.IP \[bu] 3
+The attribute was explicitly set via the
+.BR prctl (2)
+.B PR_SET_DUMPABLE
+operation.
+.IP \[bu]
+The attribute was reset to the value in the file
+.I /proc/sys/fs/suid_dumpable
+(described below), for the reasons described in
+.BR prctl (2).
+.RE
+.IP
+Resetting the "dumpable" attribute to 1 reverts the ownership of the
+.IR /proc/ pid /*
+files to the process's effective UID and GID.
+Note, however, that if the effective UID or GID is subsequently modified,
+then the "dumpable" attribute may be reset, as described in
+.BR prctl (2).
+Therefore, it may be desirable to reset the "dumpable" attribute
+.I after
+making any desired changes to the process's effective UID or GID.
+.TP
+.I /proc/self/
+This directory refers to the process accessing the
+.I /proc
+filesystem,
+and is identical to the
+.I /proc
+directory named by the process ID of the same process.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_attr.5 b/man/man5/proc_pid_attr.5
new file mode 100644
index 000000000..f005a3b5e
--- /dev/null
+++ b/man/man5/proc_pid_attr.5
@@ -0,0 +1,137 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com)
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_attr 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/attr/ \- security-related attributes
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /attr/
+.\" https://lwn.net/Articles/28222/
+.\" From:    Stephen Smalley <sds@epoch.ncsc.mil>
+.\" To:	     LKML and others
+.\" Subject: [RFC][PATCH] Process Attribute API for Security Modules
+.\" Date:    08 Apr 2003 16:17:52 -0400
+.\"
+.\"	http://www.nsa.gov/research/_files/selinux/papers/module/x362.shtml
+.\"
+The files in this directory provide an API for security modules.
+The contents of this directory are files that can be read and written
+in order to set security-related attributes.
+This directory was added to support SELinux,
+but the intention was that the API be general enough to support
+other security modules.
+For the purpose of explanation,
+examples of how SELinux uses these files are provided below.
+.IP
+This directory is present only if the kernel was configured with
+.BR CONFIG_SECURITY .
+.TP
+.IR /proc/ pid /attr/current " (since Linux 2.6.0)"
+The contents of this file represent the current
+security attributes of the process.
+.IP
+In SELinux, this file is used to get the security context of a process.
+Prior to Linux 2.6.11, this file could not be used to set the security
+context (a write was always denied), since SELinux limited process security
+transitions to
+.BR execve (2)
+(see the description of
+.IR /proc/ pid /attr/exec ,
+below).
+Since Linux 2.6.11, SELinux lifted this restriction and began supporting
+"set" operations via writes to this node if authorized by policy,
+although use of this operation is only suitable for applications that are
+trusted to maintain any desired separation between the old and new security
+contexts.
+.IP
+Prior to Linux 2.6.28, SELinux did not allow threads within a
+multithreaded process to set their security context via this node
+as it would yield an inconsistency among the security contexts of the
+threads sharing the same memory space.
+Since Linux 2.6.28, SELinux lifted
+this restriction and began supporting "set" operations for threads within
+a multithreaded process if the new security context is bounded by the old
+security context, where the bounded relation is defined in policy and
+guarantees that the new security context has a subset of the permissions
+of the old security context.
+.IP
+Other security modules may choose to support "set" operations via
+writes to this node.
+.TP
+.IR /proc/ pid /attr/exec " (since Linux 2.6.0)"
+This file represents the attributes to assign to the
+process upon a subsequent
+.BR execve (2).
+.IP
+In SELinux,
+this is needed to support role/domain transitions, and
+.BR execve (2)
+is the preferred point to make such transitions because it offers better
+control over the initialization of the process in the new security label
+and the inheritance of state.
+In SELinux, this attribute is reset on
+.BR execve (2)
+so that the new program reverts to the default behavior for any
+.BR execve (2)
+calls that it may make.
+In SELinux, a process can set
+only its own
+.IR /proc/ pid /attr/exec
+attribute.
+.TP
+.IR /proc/ pid /attr/fscreate " (since Linux 2.6.0)"
+This file represents the attributes to assign to files
+created by subsequent calls to
+.BR open (2),
+.BR mkdir (2),
+.BR symlink (2),
+and
+.BR mknod (2)
+.IP
+SELinux employs this file to support creation of a file
+(using the aforementioned system calls)
+in a secure state,
+so that there is no risk of inappropriate access being obtained
+between the time of creation and the time that attributes are set.
+In SELinux, this attribute is reset on
+.BR execve (2),
+so that the new program reverts to the default behavior for
+any file creation calls it may make, but the attribute will persist
+across multiple file creation calls within a program unless it is
+explicitly reset.
+In SELinux, a process can set only its own
+.IR /proc/ pid /attr/fscreate
+attribute.
+.TP
+.IR /proc/ pid /attr/keycreate " (since Linux 2.6.18)"
+.\" commit 4eb582cf1fbd7b9e5f466e3718a59c957e75254e
+If a process writes a security context into this file,
+all subsequently created keys
+.RB ( add_key (2))
+will be labeled with this context.
+For further information, see the kernel source file
+.I Documentation/security/keys/core.rst
+(or file
+.\" commit b68101a1e8f0263dbc7b8375d2a7c57c6216fb76
+.I Documentation/security/keys.txt
+between Linux 3.0 and Linux 4.13, or
+.\" commit d410fa4ef99112386de5f218dd7df7b4fca910b4
+.I Documentation/keys.txt
+before Linux 3.0).
+.TP
+.IR /proc/ pid /attr/prev " (since Linux 2.6.0)"
+This file contains the security context of the process before the last
+.BR execve (2);
+that is, the previous value of
+.IR /proc/ pid /attr/current .
+.TP
+.IR /proc/ pid /attr/socketcreate " (since Linux 2.6.18)"
+.\" commit 42c3e03ef6b298813557cdb997bd6db619cd65a2
+If a process writes a security context into this file,
+all subsequently created sockets will be labeled with this context.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_autogroup.5 b/man/man5/proc_pid_autogroup.5
new file mode 100644
index 000000000..9df64d1b5
--- /dev/null
+++ b/man/man5/proc_pid_autogroup.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_autogroup 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+proc_pid_autogroup \- group tasks for the scheduler
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /autogroup " (since Linux 2.6.38)"
+.\" commit 5091faa449ee0b7d73bc296a93bca9540fc51d0a
+See
+.BR sched (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_auxv.5 b/man/man5/proc_pid_auxv.5
new file mode 100644
index 000000000..2202346ea
--- /dev/null
+++ b/man/man5/proc_pid_auxv.5
@@ -0,0 +1,27 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_auxv 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/auxv \- exec(3) information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /auxv " (since Linux 2.6.0)"
+.\" Precisely: Linux 2.6.0-test7
+This contains the contents of the ELF interpreter information passed
+to the process at exec time.
+The format is one \fIunsigned long\fP ID
+plus one \fIunsigned long\fP value for each entry.
+The last entry contains two zeros.
+See also
+.BR getauxval (3).
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_cgroup.5 b/man/man5/proc_pid_cgroup.5
new file mode 100644
index 000000000..22d8deb89
--- /dev/null
+++ b/man/man5/proc_pid_cgroup.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_cgroup 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/cgroup \- control group
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /cgroup " (since Linux 2.6.24)"
+See
+.BR cgroups (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_clear_refs.5 b/man/man5/proc_pid_clear_refs.5
new file mode 100644
index 000000000..45b37fdfe
--- /dev/null
+++ b/man/man5/proc_pid_clear_refs.5
@@ -0,0 +1,87 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_clear_refs 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/clear_refs \- reset the PG_Referenced and ACCESSED/YOUNG bits
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /clear_refs " (since Linux 2.6.22)"
+.\" commit b813e931b4c8235bb42e301096ea97dbdee3e8fe (2.6.22)
+.\" commit 398499d5f3613c47f2143b8c54a04efb5d7a6da9 (2.6.32)
+.\" commit 040fa02077de01c7e08fa75be6125e4ca5636011 (3.11)
+.\"
+.\"       "Clears page referenced bits shown in smaps output"
+.\"       write-only, writable only by the owner of the process
+.IP
+This is a write-only file, writable only by owner of the process.
+.IP
+The following values may be written to the file:
+.RS
+.TP
+1 (since Linux 2.6.22)
+.\" Internally: CLEAR_REFS_ALL
+Reset the PG_Referenced and ACCESSED/YOUNG
+bits for all the pages associated with the process.
+(Before Linux 2.6.32, writing any nonzero value to this file
+had this effect.)
+.TP
+2 (since Linux 2.6.32)
+.\" Internally: CLEAR_REFS_ANON
+Reset the PG_Referenced and ACCESSED/YOUNG
+bits for all anonymous pages associated with the process.
+.TP
+3 (since Linux 2.6.32)
+.\" Internally: CLEAR_REFS_MAPPED
+Reset the PG_Referenced and ACCESSED/YOUNG
+bits for all file-mapped pages associated with the process.
+.RE
+.IP
+Clearing the PG_Referenced and ACCESSED/YOUNG bits provides a method
+to measure approximately how much memory a process is using.
+One first inspects the values in the "Referenced" fields
+for the VMAs shown in
+.IR /proc/ pid /smaps
+to get an idea of the memory footprint of the
+process.
+One then clears the PG_Referenced and ACCESSED/YOUNG bits
+and, after some measured time interval,
+once again inspects the values in the "Referenced" fields
+to get an idea of the change in memory footprint of the
+process during the measured interval.
+If one is interested only in inspecting the selected mapping types,
+then the value 2 or 3 can be used instead of 1.
+.IP
+Further values can be written to affect different properties:
+.RS
+.TP
+4 (since Linux 3.11)
+Clear the soft-dirty bit for all the pages associated with the process.
+.\" Internally: CLEAR_REFS_SOFT_DIRTY
+This is used (in conjunction with
+.IR /proc/ pid /pagemap )
+by the check-point restore system to discover which pages of a process
+have been dirtied since the file
+.IR /proc/ pid /clear_refs
+was written to.
+.TP
+5 (since Linux 4.0)
+.\" Internally: CLEAR_REFS_MM_HIWATER_RSS
+Reset the peak resident set size ("high water mark") to the process's
+current resident set size value.
+.RE
+.IP
+Writing any value to
+.IR /proc/ pid /clear_refs
+other than those listed above has no effect.
+.IP
+The
+.IR /proc/ pid /clear_refs
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_cmdline.5 b/man/man5/proc_pid_cmdline.5
new file mode 100644
index 000000000..047cacd62
--- /dev/null
+++ b/man/man5/proc_pid_cmdline.5
@@ -0,0 +1,49 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_cmdline 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/cmdline \- command line
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /cmdline
+This read-only file holds the complete command line for the process,
+unless the process is a zombie.
+.\" In Linux 2.3.26, this also used to be true if the process was swapped out.
+In the latter case, there is nothing in this file:
+that is, a read on this file will return 0 characters.
+.IP
+For processes which are still running,
+the command-line arguments appear in this file
+in the same layout as they do in process memory:
+If the process is well-behaved,
+it is a set of strings separated by null bytes (\[aq]\e0\[aq]),
+with a further null byte after the last string.
+.IP
+This is the common case,
+but processes have the freedom to
+override the memory region and
+break assumptions about the contents or format of the
+.IR /proc/ pid /cmdline
+file.
+.IP
+If, after an
+.BR execve (2),
+the process modifies its
+.I argv
+strings, those changes will show up here.
+This is not the same thing as modifying the
+.I argv
+array.
+.IP
+Furthermore, a process may change the memory location that this file refers via
+.BR prctl (2)
+operations such as
+.BR PR_SET_MM_ARG_START .
+.IP
+Think of this file as the command line that the process wants you to see.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_comm.5 b/man/man5/proc_pid_comm.5
new file mode 100644
index 000000000..80c544fa3
--- /dev/null
+++ b/man/man5/proc_pid_comm.5
@@ -0,0 +1,49 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_comm 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/comm \- command name
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /comm " (since Linux 2.6.33)"
+.\" commit 4614a696bd1c3a9af3a08f0e5874830a85b889d4
+This file exposes the process's
+.I comm
+value\[em]that is, the command name associated with the process.
+Different threads in the same process may have different
+.I comm
+values, accessible via
+.IR /proc/ pid /task/ tid /comm .
+A thread may modify its
+.I comm
+value, or that of any of other thread in the same thread group (see
+the discussion of
+.B CLONE_THREAD
+in
+.BR clone (2)),
+by writing to the file
+.IR /proc/self/task/ tid /comm .
+Strings longer than
+.B TASK_COMM_LEN
+(16) characters (including the terminating null byte) are silently truncated.
+.IP
+This file provides a superset of the
+.BR prctl (2)
+.B PR_SET_NAME
+and
+.B PR_GET_NAME
+operations, and is employed by
+.BR pthread_setname_np (3)
+when used to rename threads other than the caller.
+The value in this file is used for the
+.I %e
+specifier in
+.IR /proc/sys/kernel/core_pattern ;
+see
+.BR core (5).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_coredump_filter.5 b/man/man5/proc_pid_coredump_filter.5
new file mode 100644
index 000000000..512e64dbf
--- /dev/null
+++ b/man/man5/proc_pid_coredump_filter.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_coredump_filter 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/coredump_filter \- core dump filter
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /coredump_filter " (since Linux 2.6.23)"
+See
+.BR core (5).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_cpuset.5 b/man/man5/proc_pid_cpuset.5
new file mode 100644
index 000000000..c3a138d5a
--- /dev/null
+++ b/man/man5/proc_pid_cpuset.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_cpuset 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/cpuset \- CPU affinity sets
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /cpuset " (since Linux 2.6.12)"
+.\" and/proc/[pid]/task/[tid]/cpuset
+See
+.BR cpuset (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_cwd.5 b/man/man5/proc_pid_cwd.5
new file mode 100644
index 000000000..3accb9237
--- /dev/null
+++ b/man/man5/proc_pid_cwd.5
@@ -0,0 +1,36 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_cwd 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/cwd \- symbolic link to current working directory
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /cwd
+This is a symbolic link to the current working directory of the process.
+To find out the current working directory of process 20,
+for instance, you can do this:
+.IP
+.in +4n
+.EX
+.RB "$" " cd /proc/20/cwd; pwd \-P"
+.EE
+.in
+.IP
+.\" The following was still true as at kernel 2.6.13
+In a multithreaded process, the contents of this symbolic link
+are not available if the main thread has already terminated
+(typically by calling
+.BR pthread_exit (3)).
+.IP
+Permission to dereference or read
+.RB ( readlink (2))
+this symbolic link is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_environ.5 b/man/man5/proc_pid_environ.5
new file mode 100644
index 000000000..0ff8d4829
--- /dev/null
+++ b/man/man5/proc_pid_environ.5
@@ -0,0 +1,48 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_environ 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/environ \- initial environment
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /environ
+This file contains the initial environment that was set
+when the currently executing program was started via
+.BR execve (2).
+The entries are separated by null bytes (\[aq]\e0\[aq]),
+and there may be a null byte at the end.
+Thus, to print out the environment of process 1, you would do:
+.IP
+.in +4n
+.EX
+.RB "$" " cat /proc/1/environ | tr \[aq]\e000\[aq] \[aq]\en\[aq]"
+.EE
+.in
+.IP
+If, after an
+.BR execve (2),
+the process modifies its environment
+(e.g., by calling functions such as
+.BR putenv (3)
+or modifying the
+.BR environ (7)
+variable directly),
+this file will
+.I not
+reflect those changes.
+.IP
+Furthermore, a process may change the memory location that this file refers via
+.BR prctl (2)
+operations such as
+.BR PR_SET_MM_ENV_START .
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_exe.5 b/man/man5/proc_pid_exe.5
new file mode 100644
index 000000000..e308677f1
--- /dev/null
+++ b/man/man5/proc_pid_exe.5
@@ -0,0 +1,59 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_exe 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/exe \- symbolic link to program pathname
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /exe
+Under Linux 2.2 and later, this file is a symbolic link
+containing the actual pathname of the executed command.
+This symbolic link can be dereferenced normally; attempting to open
+it will open the executable.
+You can even type
+.IR /proc/ pid /exe
+to run another copy of the same executable that is being run by
+process
+.IR pid .
+If the pathname has been unlinked, the symbolic link will contain the
+string \[aq]\ (deleted)\[aq] appended to the original pathname.
+.\" The following was still true as at kernel 2.6.13
+In a multithreaded process, the contents of this symbolic link
+are not available if the main thread has already terminated
+(typically by calling
+.BR pthread_exit (3)).
+.IP
+Permission to dereference or read
+.RB ( readlink (2))
+this symbolic link is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.IP
+Under Linux 2.0 and earlier,
+.IR /proc/ pid /exe
+is a pointer to the binary which was executed,
+and appears as a symbolic link.
+A
+.BR readlink (2)
+call on this file under Linux 2.0 returns a string in the format:
+.IP
+.in +4n
+.EX
+[device]:inode
+.EE
+.in
+.IP
+For example, [0301]:1502 would be inode 1502 on device major 03 (IDE,
+MFM, etc. drives) minor 01 (first partition on the first drive).
+.IP
+.BR find (1)
+with the
+.I \-inum
+option can be used to locate the file.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_fd.5 b/man/man5/proc_pid_fd.5
new file mode 100644
index 000000000..2e3341ad8
--- /dev/null
+++ b/man/man5/proc_pid_fd.5
@@ -0,0 +1,161 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_fd 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/fd/ \- file descriptors
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /fd/
+This is a subdirectory containing one entry for each file which the
+process has open, named by its file descriptor, and which is a
+symbolic link to the actual file.
+Thus, 0 is standard input, 1 standard output, 2 standard error, and so on.
+.IP
+For file descriptors for pipes and sockets,
+the entries will be symbolic links whose content is the
+file type with the inode.
+A
+.BR readlink (2)
+call on this file returns a string in the format:
+.IP
+.in +4n
+.EX
+type:[inode]
+.EE
+.in
+.IP
+For example,
+.I socket:[2248868]
+will be a socket and its inode is 2248868.
+For sockets, that inode can be used to find more information
+in one of the files under
+.IR /proc/net/ .
+.IP
+For file descriptors that have no corresponding inode
+(e.g., file descriptors produced by
+.BR bpf (2),
+.BR epoll_create (2),
+.BR eventfd (2),
+.BR inotify_init (2),
+.BR perf_event_open (2),
+.BR signalfd (2),
+.BR timerfd_create (2),
+and
+.BR userfaultfd (2)),
+the entry will be a symbolic link with contents of the form
+.IP
+.in +4n
+.EX
+.RI anon_inode: file-type
+.EE
+.in
+.IP
+In many cases (but not all), the
+.I file-type
+is surrounded by square brackets.
+.IP
+For example, an epoll file descriptor will have a symbolic link
+whose content is the string
+.IR "anon_inode:[eventpoll]" .
+.IP
+.\"The following was still true as at kernel 2.6.13
+In a multithreaded process, the contents of this directory
+are not available if the main thread has already terminated
+(typically by calling
+.BR pthread_exit (3)).
+.IP
+Programs that take a filename as a command-line argument,
+but don't take input from standard input if no argument is supplied,
+and programs that write to a file named as a command-line argument,
+but don't send their output to standard output
+if no argument is supplied, can nevertheless be made to use
+standard input or standard output by using
+.IR /proc/ pid /fd
+files as command-line arguments.
+For example, assuming that
+.I \-i
+is the flag designating an input file and
+.I \-o
+is the flag designating an output file:
+.IP
+.in +4n
+.EX
+.RB "$" " foobar \-i /proc/self/fd/0 \-o /proc/self/fd/1 ..."
+.EE
+.in
+.IP
+and you have a working filter.
+.\" The following is not true in my tests (MTK):
+.\" Note that this will not work for
+.\" programs that seek on their files, as the files in the fd directory
+.\" are not seekable.
+.IP
+.I /proc/self/fd/N
+is approximately the same as
+.I /dev/fd/N
+in some UNIX and UNIX-like systems.
+Most Linux MAKEDEV scripts symbolically link
+.I /dev/fd
+to
+.IR /proc/self/fd ,
+in fact.
+.IP
+Most systems provide symbolic links
+.IR /dev/stdin ,
+.IR /dev/stdout ,
+and
+.IR /dev/stderr ,
+which respectively link to the files
+.IR 0 ,
+.IR 1 ,
+and
+.I 2
+in
+.IR /proc/self/fd .
+Thus the example command above could be written as:
+.IP
+.in +4n
+.EX
+.RB "$" " foobar \-i /dev/stdin \-o /dev/stdout ..."
+.EE
+.in
+.IP
+Permission to dereference or read
+.RB ( readlink (2))
+the symbolic links in this directory is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.IP
+Note that for file descriptors referring to inodes
+(pipes and sockets, see above),
+those inodes still have permission bits and ownership information
+distinct from those of the
+.IR /proc/ pid /fd
+entry,
+and that the owner may differ from the user and group IDs of the process.
+An unprivileged process may lack permissions to open them, as in this example:
+.IP
+.in +4n
+.EX
+.RB "$" " echo test | sudo \-u nobody cat"
+test
+.RB "$" " echo test | sudo \-u nobody cat /proc/self/fd/0"
+cat: /proc/self/fd/0: Permission denied
+.EE
+.in
+.IP
+File descriptor 0 refers to the pipe created by the shell
+and owned by that shell's user, which is not
+.IR nobody ,
+so
+.B cat
+does not have permission
+to create a new file descriptor to read from that inode,
+even though it can still read from its existing file descriptor 0.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_fdinfo.5 b/man/man5/proc_pid_fdinfo.5
new file mode 100644
index 000000000..1e23bbe02
--- /dev/null
+++ b/man/man5/proc_pid_fdinfo.5
@@ -0,0 +1,300 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_fdinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/fdinfo/ \- information about file descriptors
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /fdinfo/ " (since Linux 2.6.22)"
+This is a subdirectory containing one entry for each file which the
+process has open, named by its file descriptor.
+The files in this directory are readable only by the owner of the process.
+The contents of each file can be read to obtain information
+about the corresponding file descriptor.
+The content depends on the type of file referred to by the
+corresponding file descriptor.
+.IP
+For regular files and directories, we see something like:
+.IP
+.in +4n
+.EX
+.RB "$" " cat /proc/12015/fdinfo/4"
+pos:    1000
+flags:  01002002
+mnt_id: 21
+.EE
+.in
+.IP
+The fields are as follows:
+.RS
+.TP
+.I pos
+This is a decimal number showing the file offset.
+.TP
+.I flags
+This is an octal number that displays the
+file access mode and file status flags (see
+.BR open (2)).
+If the close-on-exec file descriptor flag is set, then
+.I flags
+will also include the value
+.BR O_CLOEXEC .
+.IP
+Before Linux 3.1,
+.\" commit 1117f72ea0217ba0cc19f05adbbd8b9a397f5ab7
+this field incorrectly displayed the setting of
+.B O_CLOEXEC
+at the time the file was opened,
+rather than the current setting of the close-on-exec flag.
+.TP
+.I
+.I mnt_id
+This field, present since Linux 3.15,
+.\" commit 49d063cb353265c3af701bab215ac438ca7df36d
+is the ID of the mount containing this file.
+See the description of
+.IR /proc/ pid /mountinfo .
+.RE
+.IP
+For eventfd file descriptors (see
+.BR eventfd (2)),
+we see (since Linux 3.8)
+.\" commit cbac5542d48127b546a23d816380a7926eee1c25
+the following fields:
+.IP
+.in +4n
+.EX
+pos:	0
+flags:	02
+mnt_id:	10
+eventfd\-count:               40
+.EE
+.in
+.IP
+.I eventfd\-count
+is the current value of the eventfd counter, in hexadecimal.
+.IP
+For epoll file descriptors (see
+.BR epoll (7)),
+we see (since Linux 3.8)
+.\" commit 138d22b58696c506799f8de759804083ff9effae
+the following fields:
+.IP
+.in +4n
+.EX
+pos:	0
+flags:	02
+mnt_id:	10
+tfd:        9 events:       19 data: 74253d2500000009
+tfd:        7 events:       19 data: 74253d2500000007
+.EE
+.in
+.IP
+Each of the lines beginning
+.I tfd
+describes one of the file descriptors being monitored via
+the epoll file descriptor (see
+.BR epoll_ctl (2)
+for some details).
+The
+.I tfd
+field is the number of the file descriptor.
+The
+.I events
+field is a hexadecimal mask of the events being monitored for this file
+descriptor.
+The
+.I data
+field is the data value associated with this file descriptor.
+.IP
+For signalfd file descriptors (see
+.BR signalfd (2)),
+we see (since Linux 3.8)
+.\" commit 138d22b58696c506799f8de759804083ff9effae
+the following fields:
+.IP
+.in +4n
+.EX
+pos:	0
+flags:	02
+mnt_id:	10
+sigmask:	0000000000000006
+.EE
+.in
+.IP
+.I sigmask
+is the hexadecimal mask of signals that are accepted via this
+signalfd file descriptor.
+(In this example, bits 2 and 3 are set, corresponding to the signals
+.B SIGINT
+and
+.BR SIGQUIT ;
+see
+.BR signal (7).)
+.IP
+For inotify file descriptors (see
+.BR inotify (7)),
+we see (since Linux 3.8)
+the following fields:
+.IP
+.in +4n
+.EX
+pos:	0
+flags:	00
+mnt_id:	11
+inotify wd:2 ino:7ef82a sdev:800001 mask:800afff ignored_mask:0 fhandle\-bytes:8 fhandle\-type:1 f_handle:2af87e00220ffd73
+inotify wd:1 ino:192627 sdev:800001 mask:800afff ignored_mask:0 fhandle\-bytes:8 fhandle\-type:1 f_handle:27261900802dfd73
+.EE
+.in
+.IP
+Each of the lines beginning with "inotify" displays information about
+one file or directory that is being monitored.
+The fields in this line are as follows:
+.RS
+.TP
+.I wd
+A watch descriptor number (in decimal).
+.TP
+.I ino
+The inode number of the target file (in hexadecimal).
+.TP
+.I sdev
+The ID of the device where the target file resides (in hexadecimal).
+.TP
+.I mask
+The mask of events being monitored for the target file (in hexadecimal).
+.RE
+.IP
+If the kernel was built with exportfs support, the path to the target
+file is exposed as a file handle, via three hexadecimal fields:
+.IR fhandle\-bytes ,
+.IR fhandle\-type ,
+and
+.IR f_handle .
+.IP
+For fanotify file descriptors (see
+.BR fanotify (7)),
+we see (since Linux 3.8)
+the following fields:
+.IP
+.in +4n
+.EX
+pos:	0
+flags:	02
+mnt_id:	11
+fanotify flags:0 event\-flags:88002
+fanotify ino:19264f sdev:800001 mflags:0 mask:1 ignored_mask:0 fhandle\-bytes:8 fhandle\-type:1 f_handle:4f261900a82dfd73
+.EE
+.in
+.IP
+The fourth line displays information defined when the fanotify group
+was created via
+.BR fanotify_init (2):
+.RS
+.TP
+.I flags
+The
+.I flags
+argument given to
+.BR fanotify_init (2)
+(expressed in hexadecimal).
+.TP
+.I event\-flags
+The
+.I event_f_flags
+argument given to
+.BR fanotify_init (2)
+(expressed in hexadecimal).
+.RE
+.IP
+Each additional line shown in the file contains information
+about one of the marks in the fanotify group.
+Most of these fields are as for inotify, except:
+.RS
+.TP
+.I mflags
+The flags associated with the mark
+(expressed in hexadecimal).
+.TP
+.I mask
+The events mask for this mark
+(expressed in hexadecimal).
+.TP
+.I ignored_mask
+The mask of events that are ignored for this mark
+(expressed in hexadecimal).
+.RE
+.IP
+For details on these fields, see
+.BR fanotify_mark (2).
+.IP
+For timerfd file descriptors (see
+.BR timerfd (2)),
+we see (since Linux 3.17)
+.\" commit af9c4957cf212ad9cf0bee34c95cb11de5426e85
+the following fields:
+.IP
+.in +4n
+.EX
+pos:    0
+flags:  02004002
+mnt_id: 13
+clockid: 0
+ticks: 0
+settime flags: 03
+it_value: (7695568592, 640020877)
+it_interval: (0, 0)
+.EE
+.in
+.RS
+.TP
+.I clockid
+This is the numeric value of the clock ID
+(corresponding to one of the
+.B CLOCK_*
+constants defined via
+.IR <time.h> )
+that is used to mark the progress of the timer (in this example, 0 is
+.BR CLOCK_REALTIME ).
+.TP
+.I ticks
+This is the number of timer expirations that have occurred,
+(i.e., the value that
+.BR read (2)
+on it would return).
+.TP
+.I settime flags
+This field lists the flags with which the timerfd was last armed (see
+.BR timerfd_settime (2)),
+in octal
+(in this example, both
+.B TFD_TIMER_ABSTIME
+and
+.B TFD_TIMER_CANCEL_ON_SET
+are set).
+.TP
+.I it_value
+This field contains the amount of time until the timer will next expire,
+expressed in seconds and nanoseconds.
+This is always expressed as a relative value,
+regardless of whether the timer was created using the
+.B TFD_TIMER_ABSTIME
+flag.
+.TP
+.I it_interval
+This field contains the interval of the timer,
+in seconds and nanoseconds.
+(The
+.I it_value
+and
+.I it_interval
+fields contain the values that
+.BR timerfd_gettime (2)
+on this file descriptor would return.)
+.RE
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_gid_map.5 b/man/man5/proc_pid_gid_map.5
new file mode 100644
index 000000000..4637389d1
--- /dev/null
+++ b/man/man5/proc_pid_gid_map.5
@@ -0,0 +1 @@
+.so man5/proc_pid_uid_map.5
diff --git a/man/man5/proc_pid_io.5 b/man/man5/proc_pid_io.5
new file mode 100644
index 000000000..a208e748f
--- /dev/null
+++ b/man/man5/proc_pid_io.5
@@ -0,0 +1,100 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_io 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/io \- I/O statistics
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /io " (since Linux 2.6.20)"
+.\" commit 7c3ab7381e79dfc7db14a67c6f4f3285664e1ec2
+This file contains I/O statistics
+for the process and its waited-for children,
+for example:
+.IP
+.in +4n
+.EX
+.RB "#" " cat /proc/3828/io"
+rchar: 323934931
+wchar: 323929600
+syscr: 632687
+syscw: 632675
+read_bytes: 0
+write_bytes: 323932160
+cancelled_write_bytes: 0
+.EE
+.in
+.IP
+The fields are as follows:
+.RS
+.TP
+.IR rchar ": characters read"
+The number of bytes
+returned by successful
+.BR read (2)
+and similar system calls.
+.TP
+.IR wchar ": characters written"
+The number of bytes
+returned by successful
+.BR write (2)
+and similar system calls.
+.TP
+.IR syscr ": read syscalls"
+The number of "file read" system calls\[em]those from the
+.BR read (2)
+family,
+.BR sendfile (2),
+.BR copy_file_range (2),
+and
+.BR ioctl (2)
+.BR BTRFS_IOC_ENCODED_READ [ _32 ]
+(including when invoked by the kernel as part of other syscalls).
+.TP
+.IR syscw ": write syscalls"
+The number of "file write" system calls\[em]those from the
+.BR write (2)
+family,
+.BR sendfile (2),
+.BR copy_file_range (2),
+and
+.BR ioctl (2)
+.BR BTRFS_IOC_ENCODED_WRITE [ _32 ]
+(including when invoked by the kernel as part of other syscalls).
+.TP
+.IR read_bytes ": bytes read"
+The number of bytes really fetched from the storage layer.
+This is accurate for block-backed filesystems.
+.TP
+.IR write_bytes ": bytes written"
+The number of bytes really sent to the storage layer.
+.TP
+.IR cancelled_write_bytes :
+The above statistics fail to account for truncation:
+if a process writes 1 MB to a regular file and then removes it,
+said 1 MB will not be written, but
+.I will
+have nevertheless been accounted as a 1 MB write.
+This field represents the number of bytes "saved" from I/O writeback.
+This can yield to having done negative I/O
+if caches dirtied by another process are truncated.
+.I cancelled_write_bytes
+applies to I/O already accounted-for in
+.IR write_bytes .
+.RE
+.IP
+Permission to access this file is governed by
+.BR ptrace (2)
+access mode
+.BR PTRACE_MODE_READ_FSCREDS .
+.SH CAVEATS
+These counters are not atomic:
+on systems where 64-bit integer operations may tear,
+a counter could be updated simultaneously with a read,
+yielding an incorrect intermediate value.
+.SH SEE ALSO
+.BR getrusage (2),
+.BR proc (5)
diff --git a/man/man5/proc_pid_limits.5 b/man/man5/proc_pid_limits.5
new file mode 100644
index 000000000..9e34495a8
--- /dev/null
+++ b/man/man5/proc_pid_limits.5
@@ -0,0 +1,25 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_oid_limits 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/limits \- resource limits
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /limits " (since Linux 2.6.24)"
+This file displays the soft limit, hard limit, and units of measurement
+for each of the process's resource limits (see
+.BR getrlimit (2)).
+Up to and including Linux 2.6.35,
+this file is protected to allow reading only by the real UID of the process.
+Since Linux 2.6.36,
+.\" commit 3036e7b490bf7878c6dae952eec5fb87b1106589
+this file is readable by all users on the system.
+.\" FIXME Describe /proc/[pid]/loginuid
+.\"       Added in Linux 2.6.11; updating requires CAP_AUDIT_CONTROL
+.\"       CONFIG_AUDITSYSCALL
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_map_files.5 b/man/man5/proc_pid_map_files.5
new file mode 100644
index 000000000..da726dcfc
--- /dev/null
+++ b/man/man5/proc_pid_map_files.5
@@ -0,0 +1,72 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_map_files 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/map_files/ \- memory-mapped files
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /map_files/ " (since Linux 3.3)"
+.\" commit 640708a2cff7f81e246243b0073c66e6ece7e53e
+This subdirectory contains entries corresponding to memory-mapped
+files (see
+.BR mmap (2)).
+Entries are named by memory region start and end
+address pair (expressed as hexadecimal numbers),
+and are symbolic links to the mapped files themselves.
+Here is an example,
+with the output wrapped and reformatted to fit on an 80-column display:
+.IP
+.in +4n
+.EX
+.RB "#" " ls \-l /proc/self/map_files/"
+lr\-\-\-\-\-\-\-\-. 1 root root 64 Apr 16 21:31
+            3252e00000\-3252e20000 \-> /usr/lib64/ld\-2.15.so
+\&...
+.EE
+.in
+.IP
+Although these entries are present for memory regions that were
+mapped with the
+.B MAP_FILE
+flag, the way anonymous shared memory (regions created with the
+.B MAP_ANON | MAP_SHARED
+flags)
+is implemented in Linux
+means that such regions also appear on this directory.
+Here is an example where the target file is the deleted
+.I /dev/zero
+one:
+.IP
+.in +4n
+.EX
+lrw\-\-\-\-\-\-\-. 1 root root 64 Apr 16 21:33
+            7fc075d2f000\-7fc075e6f000 \-> /dev/zero (deleted)
+.EE
+.in
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.IP
+Until Linux 4.3,
+.\" commit bdb4d100afe9818aebd1d98ced575c5ef143456c
+this directory appeared only if the
+.B CONFIG_CHECKPOINT_RESTORE
+kernel configuration option was enabled.
+.IP
+Capabilities are required to read the contents of the symbolic links in
+this directory: before Linux 5.9, the reading process requires
+.B CAP_SYS_ADMIN
+in the initial user namespace;
+since Linux 5.9, the reading process must have either
+.B CAP_SYS_ADMIN
+or
+.B CAP_CHECKPOINT_RESTORE
+in the initial (i.e. root) user namespace.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_maps.5 b/man/man5/proc_pid_maps.5
new file mode 100644
index 000000000..36efa5702
--- /dev/null
+++ b/man/man5/proc_pid_maps.5
@@ -0,0 +1,156 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_maps 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/maps \- mapped memory regions
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /maps
+A file containing the currently mapped memory regions and their access
+permissions.
+See
+.BR mmap (2)
+for some further information about memory mappings.
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.IP
+The format of the file is:
+.IP
+.in +4n
+.EX
+.I "address           perms offset  dev   inode       pathname"
+00400000\-00452000 r\-xp 00000000 08:02 173521      /usr/bin/dbus\-daemon
+00651000\-00652000 r\-\-p 00051000 08:02 173521      /usr/bin/dbus\-daemon
+00652000\-00655000 rw\-p 00052000 08:02 173521      /usr/bin/dbus\-daemon
+00e03000\-00e24000 rw\-p 00000000 00:00 0           [heap]
+00e24000\-011f7000 rw\-p 00000000 00:00 0           [heap]
+\&...
+35b1800000\-35b1820000 r\-xp 00000000 08:02 135522  /usr/lib64/ld\-2.15.so
+35b1a1f000\-35b1a20000 r\-\-p 0001f000 08:02 135522  /usr/lib64/ld\-2.15.so
+35b1a20000\-35b1a21000 rw\-p 00020000 08:02 135522  /usr/lib64/ld\-2.15.so
+35b1a21000\-35b1a22000 rw\-p 00000000 00:00 0
+35b1c00000\-35b1dac000 r\-xp 00000000 08:02 135870  /usr/lib64/libc\-2.15.so
+35b1dac000\-35b1fac000 \-\-\-p 001ac000 08:02 135870  /usr/lib64/libc\-2.15.so
+35b1fac000\-35b1fb0000 r\-\-p 001ac000 08:02 135870  /usr/lib64/libc\-2.15.so
+35b1fb0000\-35b1fb2000 rw\-p 001b0000 08:02 135870  /usr/lib64/libc\-2.15.so
+\&...
+f2c6ff8c000\-7f2c7078c000 rw\-p 00000000 00:00 0    [stack:986]
+\&...
+7fffb2c0d000\-7fffb2c2e000 rw\-p 00000000 00:00 0   [stack]
+7fffb2d48000\-7fffb2d49000 r\-xp 00000000 00:00 0   [vdso]
+.EE
+.in
+.IP
+The
+.I address
+field is the address space in the process that the mapping occupies.
+The
+.I perms
+field is a set of permissions:
+.IP
+.in +4n
+.EX
+r = read
+w = write
+x = execute
+s = shared
+p = private (copy on write)
+.EE
+.in
+.IP
+The
+.I offset
+field is the offset into the file/whatever;
+.I dev
+is the device
+(major:minor);
+.I inode
+is the inode on that device.
+0 indicates that no inode is associated with the memory region,
+as would be the case with BSS (uninitialized data).
+.IP
+The
+.I pathname
+field will usually be the file that is backing the mapping.
+For ELF files,
+you can easily coordinate with the
+.I offset
+field by looking at the
+Offset field in the ELF program headers
+.RI ( "readelf\ \-l" ).
+.IP
+There are additional helpful pseudo-paths:
+.RS
+.TP
+.I [stack]
+The initial process's (also known as the main thread's) stack.
+.TP
+.IR [stack: tid ] " (from Linux 3.4 to Linux 4.4)"
+.\" commit b76437579d1344b612cf1851ae610c636cec7db0 (added)
+.\" commit 65376df582174ffcec9e6471bf5b0dd79ba05e4a (removed)
+A thread's stack (where the
+.I tid
+is a thread ID).
+It corresponds to the
+.IR /proc/ pid /task/ tid /
+path.
+This field was removed in Linux 4.5, since providing this information
+for a process with large numbers of threads is expensive.
+.TP
+.I [vdso]
+The virtual dynamically linked shared object.
+See
+.BR vdso (7).
+.TP
+.I [heap]
+The process's heap.
+.TP
+.IR [anon: name ] " (since Linux 5.17)"
+.\" Commit 9a10064f5625d5572c3626c1516e0bebc6c9fe9b
+A named private anonymous mapping.
+Set with
+.BR prctl (2)
+.BR PR_SET_VMA_ANON_NAME .
+.TP
+.IR [anon_shmem: name ] " (since Linux 6.2)"
+.\" Commit d09e8ca6cb93bb4b97517a18fbbf7eccb0e9ff43
+A named shared anonymous mapping.
+Set with
+.BR prctl (2)
+.BR PR_SET_VMA_ANON_NAME .
+.in
+.RE
+.IP
+If the
+.I pathname
+field is blank,
+this is an anonymous mapping as obtained via
+.BR mmap (2).
+There is no easy way to coordinate this back to a process's source,
+short of running it through
+.BR gdb (1),
+.BR strace (1),
+or similar.
+.IP
+.I pathname
+is shown unescaped except for newline characters, which are replaced
+with an octal escape sequence.
+As a result, it is not possible to determine whether the original
+pathname contained a newline character or the literal
+.I \e012
+character sequence.
+.IP
+If the mapping is file-backed and the file has been deleted, the string
+" (deleted)" is appended to the pathname.
+Note that this is ambiguous too.
+.IP
+Under Linux 2.0, there is no field giving pathname.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_mem.5 b/man/man5/proc_pid_mem.5
new file mode 100644
index 000000000..42025332c
--- /dev/null
+++ b/man/man5/proc_pid_mem.5
@@ -0,0 +1,24 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_mem 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/mem \- memory
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /mem
+This file can be used to access the pages of a process's memory through
+.BR open (2),
+.BR read (2),
+and
+.BR lseek (2).
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_mountinfo.5 b/man/man5/proc_pid_mountinfo.5
new file mode 100644
index 000000000..678063617
--- /dev/null
+++ b/man/man5/proc_pid_mountinfo.5
@@ -0,0 +1,124 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_mountinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/mountinfo \- mount information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /mountinfo " (since Linux 2.6.26)"
+.\" This info adapted from Documentation/filesystems/proc.txt
+.\" commit 2d4d4864ac08caff5c204a752bd004eed4f08760
+This file contains information about mounts
+in the process's mount namespace (see
+.BR mount_namespaces (7)).
+It supplies various information
+(e.g., propagation state, root of mount for bind mounts,
+identifier for each mount and its parent) that is missing from the (older)
+.IR /proc/ pid /mounts
+file, and fixes various other problems with that file
+(e.g., nonextensibility,
+failure to distinguish per-mount versus per-superblock options).
+.IP
+The file contains lines of the form:
+.IP
+.EX
+36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 \- ext3 /dev/root rw,errors=continue
+(1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)
+.EE
+.IP
+The numbers in parentheses are labels for the descriptions below:
+.RS 7
+.TP 5
+(1)
+mount ID: a unique ID for the mount (may be reused after
+.BR umount (2)).
+.TP
+(2)
+parent ID: the ID of the parent mount
+(or of self for the root of this mount namespace's mount tree).
+.IP
+If a new mount is stacked on top of a previous existing mount
+(so that it hides the existing mount) at pathname P,
+then the parent of the new mount is the previous mount at that location.
+Thus, when looking at all the mounts stacked at a particular location,
+the top-most mount is the one that is not the parent
+of any other mount at the same location.
+(Note, however, that this top-most mount will be accessible only if
+the longest path subprefix of P that is a mount point
+is not itself hidden by a stacked mount.)
+.IP
+If the parent mount lies outside the process's root directory (see
+.BR chroot (2)),
+the ID shown here won't have a corresponding record in
+.I mountinfo
+whose mount ID (field 1) matches this parent mount ID
+(because mounts that lie outside the process's root directory
+are not shown in
+.IR mountinfo ).
+As a special case of this point,
+the process's root mount may have a parent mount
+(for the initramfs filesystem) that lies
+.\" Miklos Szeredi, Nov 2017: The hidden one is the initramfs, I believe
+.\" mtk: In the initial mount namespace, this hidden ID has the value 0
+outside the process's root directory,
+and an entry for that mount will not appear in
+.IR mountinfo .
+.TP
+(3)
+major:minor: the value of
+.I st_dev
+for files on this filesystem (see
+.BR stat (2)).
+.TP
+(4)
+root: the pathname of the directory in the filesystem
+which forms the root of this mount.
+.TP
+(5)
+mount point: the pathname of the mount point relative
+to the process's root directory.
+.TP
+(6)
+mount options: per-mount options (see
+.BR mount (2)).
+.TP
+(7)
+optional fields: zero or more fields of the form "tag[:value]"; see below.
+.TP
+(8)
+separator: the end of the optional fields is marked by a single hyphen.
+.TP
+(9)
+filesystem type: the filesystem type in the form "type[.subtype]".
+.TP
+(10)
+mount source: filesystem-specific information or "none".
+.TP
+(11)
+super options: per-superblock options (see
+.BR mount (2)).
+.RE
+.IP
+Currently, the possible optional fields are
+.IR shared ,
+.IR master ,
+.IR propagate_from ,
+and
+.IR unbindable .
+See
+.BR mount_namespaces (7)
+for a description of these fields.
+Parsers should ignore all unrecognized optional fields.
+.IP
+For more information on mount propagation see
+.I Documentation/filesystems/sharedsubtree.rst
+(or
+.I Documentation/filesystems/sharedsubtree.txt
+before Linux 5.8)
+in the Linux kernel source tree.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_mounts.5 b/man/man5/proc_pid_mounts.5
new file mode 100644
index 000000000..907eb698e
--- /dev/null
+++ b/man/man5/proc_pid_mounts.5
@@ -0,0 +1,49 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_mounts 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/mounts \- mounted filesystems
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /mounts " (since Linux 2.4.19)"
+This file lists all the filesystems currently mounted in the
+process's mount namespace (see
+.BR mount_namespaces (7)).
+The format of this file is documented in
+.BR fstab (5).
+.IP
+Since Linux 2.6.15, this file is pollable:
+after opening the file for reading, a change in this file
+(i.e., a filesystem mount or unmount) causes
+.BR select (2)
+to mark the file descriptor as having an exceptional condition, and
+.BR poll (2)
+and
+.BR epoll_wait (2)
+mark the file as having a priority event
+.RB ( POLLPRI ).
+(Before Linux 2.6.30,
+a change in this file was indicated by the file descriptor
+being marked as readable for
+.BR select (2),
+and being marked as having an error condition for
+.BR poll (2)
+and
+.BR epoll_wait (2).)
+.TP
+.I /proc/mounts
+Before Linux 2.4.19, this file was a list
+of all the filesystems currently mounted on the system.
+With the introduction of per-process mount namespaces in Linux 2.4.19 (see
+.BR mount_namespaces (7)),
+this file became a link to
+.IR /proc/self/mounts ,
+which lists the mounts of the process's own mount namespace.
+The format of this file is documented in
+.BR fstab (5).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_mountstats.5 b/man/man5/proc_pid_mountstats.5
new file mode 100644
index 000000000..6d2aa5985
--- /dev/null
+++ b/man/man5/proc_pid_mountstats.5
@@ -0,0 +1,46 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_mountstats 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/mountstats \- mount statistics
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /mountstats " (since Linux 2.6.17)"
+This file exports information (statistics, configuration information)
+about the mounts in the process's mount namespace (see
+.BR mount_namespaces (7)).
+Lines in this file have the form:
+.IP
+.in +4n
+.EX
+device /dev/sda7 mounted on /home with fstype ext3 [stats]
+(       1      )            ( 2 )             (3 ) (  4  )
+.EE
+.in
+.IP
+The fields in each line are:
+.RS 7
+.TP 5
+(1)
+The name of the mounted device
+(or "nodevice" if there is no corresponding device).
+.TP
+(2)
+The mount point within the filesystem tree.
+.TP
+(3)
+The filesystem type.
+.TP
+(4)
+Optional statistics and configuration information.
+Currently (as at Linux 2.6.26), only NFS filesystems export
+information via this field.
+.RE
+.IP
+This file is readable only by the owner of the process.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_net.5 b/man/man5/proc_pid_net.5
new file mode 100644
index 000000000..29de0b682
--- /dev/null
+++ b/man/man5/proc_pid_net.5
@@ -0,0 +1,298 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Alan Cox <A.Cox@swansea.ac.uk>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_net 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/net/, /proc/net/ \- network layer information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /net/ " (since Linux 2.6.25)"
+See the description of
+.IR /proc/net .
+.TP
+.I /proc/net/
+This directory contains various files and subdirectories containing
+information about the networking layer.
+The files contain ASCII structures and are,
+therefore, readable with
+.BR cat (1).
+However, the standard
+.BR netstat (8)
+suite provides much cleaner access to these files.
+.IP
+With the advent of network namespaces,
+various information relating to the network stack is virtualized (see
+.BR network_namespaces (7)).
+Thus, since Linux 2.6.25,
+.\" commit e9720acd728a46cb40daa52c99a979f7c4ff195c
+.I /proc/net
+is a symbolic link to the directory
+.IR /proc/self/net ,
+which contains the same files and directories as listed below.
+However, these files and directories now expose information
+for the network namespace of which the process is a member.
+.TP
+.I /proc/net/arp
+This holds an ASCII readable dump of the kernel ARP table used for
+address resolutions.
+It will show both dynamically learned and preprogrammed ARP entries.
+The format is:
+.IP
+.in +4n
+.EX
+IP address     HW type   Flags     HW address          Mask   Device
+192.168.0.50   0x1       0x2       00:50:BF:25:68:F3   *      eth0
+192.168.0.250  0x1       0xc       00:00:00:00:00:00   *      eth0
+.EE
+.in
+.IP
+Here "IP address" is the IPv4 address of the machine and the "HW type"
+is the hardware type of the address from RFC\ 826.
+The flags are the internal
+flags of the ARP structure (as defined in
+.IR /usr/include/linux/if_arp.h )
+and
+the "HW address" is the data link layer mapping for that IP address if
+it is known.
+.TP
+.I /proc/net/dev
+The dev pseudo-file contains network device status information.
+This gives
+the number of received and sent packets, the number of errors and
+collisions
+and other basic statistics.
+These are used by the
+.BR ifconfig (8)
+program to report device status.
+The format is:
+.IP
+.EX
+Inter\-|   Receive                                                |  Transmit
+ face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
+    lo: 2776770   11307    0    0    0     0          0         0  2776770   11307    0    0    0     0       0          0
+  eth0: 1215645    2751    0    0    0     0          0         0  1782404    4324    0    0    0   427       0          0
+  ppp0: 1622270    5552    1    0    0     0          0         0   354130    5669    0    0    0     0       0          0
+  tap0:    7714      81    0    0    0     0          0         0     7714      81    0    0    0     0       0          0
+.EE
+.\" .TP
+.\" .I /proc/net/ipx
+.\" No information.
+.\" .TP
+.\" .I /proc/net/ipx_route
+.\" No information.
+.TP
+.I /proc/net/dev_mcast
+Defined in
+.IR /usr/src/linux/net/core/dev_mcast.c :
+.IP
+.in +4n
+.EX
+indx interface_name  dmi_u dmi_g dmi_address
+2    eth0            1     0     01005e000001
+3    eth1            1     0     01005e000001
+4    eth2            1     0     01005e000001
+.EE
+.in
+.TP
+.I /proc/net/igmp
+Internet Group Management Protocol.
+Defined in
+.IR /usr/src/linux/net/core/igmp.c .
+.TP
+.I /proc/net/rarp
+This file uses the same format as the
+.I arp
+file and contains the current reverse mapping database used to provide
+.BR rarp (8)
+reverse address lookup services.
+If RARP is not configured into the
+kernel,
+this file will not be present.
+.TP
+.I /proc/net/raw
+Holds a dump of the RAW socket table.
+Much of the information is not of
+use
+apart from debugging.
+The "sl" value is the kernel hash slot for the
+socket,
+the "local_address" is the local address and protocol number pair.
+\&"St" is
+the internal status of the socket.
+The "tx_queue" and "rx_queue" are the
+outgoing and incoming data queue in terms of kernel memory usage.
+The "tr", "tm\->when", and "rexmits" fields are not used by RAW.
+The "uid"
+field holds the effective UID of the creator of the socket.
+.\" .TP
+.\" .I /proc/net/route
+.\" No information, but looks similar to
+.\" .BR route (8).
+.TP
+.I /proc/net/snmp
+This file holds the ASCII data needed for the IP, ICMP, TCP, and UDP
+management
+information bases for an SNMP agent.
+.TP
+.I /proc/net/tcp
+Holds a dump of the TCP socket table.
+Much of the information is not
+of use apart from debugging.
+The "sl" value is the kernel hash slot
+for the socket, the "local_address" is the local address and port number pair.
+The "rem_address" is the remote address and port number pair
+(if connected).
+\&"St" is the internal status of the socket.
+The "tx_queue" and "rx_queue" are the
+outgoing and incoming data queue in terms of kernel memory usage.
+The "tr", "tm\->when", and "rexmits" fields hold internal information of
+the kernel socket state and are useful only for debugging.
+The "uid"
+field holds the effective UID of the creator of the socket.
+.TP
+.I /proc/net/udp
+Holds a dump of the UDP socket table.
+Much of the information is not of
+use apart from debugging.
+The "sl" value is the kernel hash slot for the
+socket, the "local_address" is the local address and port number pair.
+The "rem_address" is the remote address and port number pair
+(if connected).
+"St" is the internal status of the socket.
+The "tx_queue" and "rx_queue" are the outgoing and incoming data queue
+in terms of kernel memory usage.
+The "tr", "tm\->when", and "rexmits" fields
+are not used by UDP.
+The "uid"
+field holds the effective UID of the creator of the socket.
+The format is:
+.IP
+.EX
+sl  local_address rem_address   st tx_queue rx_queue tr rexmits  tm\->when uid
+ 1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0
+ 1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0
+ 1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0
+.EE
+.TP
+.I /proc/net/unix
+Lists the UNIX domain sockets present within the system and their
+status.
+The format is:
+.IP
+.EX
+Num RefCount Protocol Flags    Type St Inode Path
+ 0: 00000002 00000000 00000000 0001 03    42
+ 1: 00000001 00000000 00010000 0001 01  1948 /dev/printer
+.EE
+.IP
+The fields are as follows:
+.RS
+.TP 10
+.IR Num :
+the kernel table slot number.
+.TP
+.IR RefCount :
+the number of users of the socket.
+.TP
+.IR Protocol :
+currently always 0.
+.TP
+.IR Flags :
+the internal kernel flags holding the status of the socket.
+.TP
+.IR Type :
+the socket type.
+For
+.B SOCK_STREAM
+sockets, this is 0001; for
+.B SOCK_DGRAM
+sockets, it is 0002; and for
+.B SOCK_SEQPACKET
+sockets, it is 0005.
+.TP
+.IR St :
+the internal state of the socket.
+.TP
+.IR Inode :
+the inode number of the socket.
+.TP
+.IR Path :
+the bound pathname (if any) of the socket.
+Sockets in the abstract namespace are included in the list,
+and are shown with a
+.I Path
+that commences with the character '@'.
+.RE
+.TP
+.I /proc/net/netfilter/nfnetlink_queue
+This file contains information about netfilter user-space queueing, if used.
+Each line represents a queue.
+Queues that have not been subscribed to
+by user space are not shown.
+.IP
+.in +4n
+.EX
+   1   4207     0  2 65535     0     0        0  1
+  (1)   (2)    (3)(4)  (5)    (6)   (7)      (8)
+.EE
+.in
+.IP
+The fields in each line are:
+.RS 7
+.TP 5
+(1)
+The ID of the queue.
+This matches what is specified in the
+.B \-\-queue\-num
+or
+.B \-\-queue\-balance
+options to the
+.BR iptables (8)
+NFQUEUE target.
+See
+.BR iptables\-extensions (8)
+for more information.
+.TP
+(2)
+The netlink port ID subscribed to the queue.
+.TP
+(3)
+The number of packets currently queued and waiting to be processed by
+the application.
+.TP
+(4)
+The copy mode of the queue.
+It is either 1 (metadata only) or 2
+(also copy payload data to user space).
+.TP
+(5)
+Copy range; that is, how many bytes of packet payload should be copied to
+user space at most.
+.TP
+(6)
+queue dropped.
+Number of packets that had to be dropped by the kernel because
+too many packets are already waiting for user space to send back the mandatory
+accept/drop verdicts.
+.TP
+(7)
+queue user dropped.
+Number of packets that were dropped within the netlink
+subsystem.
+Such drops usually happen when the corresponding socket buffer is
+full; that is, user space is not able to read messages fast enough.
+.TP
+(8)
+sequence number.
+Every queued packet is associated with a (32-bit)
+monotonically increasing sequence number.
+This shows the ID of the most recent packet queued.
+.RE
+.IP
+The last number exists only for compatibility reasons and is always 1.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_ns.5 b/man/man5/proc_pid_ns.5
new file mode 100644
index 000000000..fba490d79
--- /dev/null
+++ b/man/man5/proc_pid_ns.5
@@ -0,0 +1,20 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_ns 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/ns/ \- namespaces
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /ns/ " (since Linux 3.0)"
+.\" See commit 6b4e306aa3dc94a0545eb9279475b1ab6209a31f
+This is a subdirectory containing one entry for each namespace that
+supports being manipulated by
+.BR setns (2).
+For more information, see
+.BR namespaces (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_numa_maps.5 b/man/man5/proc_pid_numa_maps.5
new file mode 100644
index 000000000..36a9b6999
--- /dev/null
+++ b/man/man5/proc_pid_numa_maps.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_numa_maps 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/numa_maps \- NUMA memory policy and allocation
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /numa_maps " (since Linux 2.6.14)"
+See
+.BR numa (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_oom_adj.5 b/man/man5/proc_pid_oom_adj.5
new file mode 100644
index 000000000..511204462
--- /dev/null
+++ b/man/man5/proc_pid_oom_adj.5
@@ -0,0 +1 @@
+.so man5/proc_pid_oom_score_adj.5
diff --git a/man/man5/proc_pid_oom_score.5 b/man/man5/proc_pid_oom_score.5
new file mode 100644
index 000000000..6849e8dce
--- /dev/null
+++ b/man/man5/proc_pid_oom_score.5
@@ -0,0 +1,58 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_oom_score 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/oom_score \- OOM-killer score
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /oom_score " (since Linux 2.6.11)"
+.\" See mm/oom_kill.c::badness() before Linux 2.6.36 sources
+.\" See mm/oom_kill.c::oom_badness() after Linux 2.6.36
+.\" commit a63d83f427fbce97a6cea0db2e64b0eb8435cd10
+This file displays the current score that the kernel gives to
+this process for the purpose of selecting a process
+for the OOM-killer.
+A higher score means that the process is more likely to be
+selected by the OOM-killer.
+The basis for this score is the amount of memory used by the process,
+with increases (+) or decreases (\-) for factors including:
+.\" See mm/oom_kill.c::badness() before Linux 2.6.36 sources
+.\" See mm/oom_kill.c::oom_badness() after Linux 2.6.36
+.\" commit a63d83f427fbce97a6cea0db2e64b0eb8435cd10
+.RS
+.IP \[bu] 3
+whether the process is privileged (\-).
+.\" More precisely, if it has CAP_SYS_ADMIN or (pre 2.6.36) CAP_SYS_RESOURCE
+.RE
+.IP
+Before Linux 2.6.36
+the following factors were also used in the calculation of oom_score:
+.RS
+.IP \[bu] 3
+whether the process creates a lot of children using
+.BR fork (2)
+(+);
+.IP \[bu]
+whether the process has been running a long time,
+or has used a lot of CPU time (\-);
+.IP \[bu]
+whether the process has a low nice value (i.e., > 0) (+); and
+.IP \[bu]
+whether the process is making direct hardware access (\-).
+.\" More precisely, if it has CAP_SYS_RAWIO
+.RE
+.IP
+The
+.I oom_score
+also reflects the adjustment specified by the
+.I oom_score_adj
+or
+.I oom_adj
+setting for the process.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_pid_oom_score_adj (5)
diff --git a/man/man5/proc_pid_oom_score_adj.5 b/man/man5/proc_pid_oom_score_adj.5
new file mode 100644
index 000000000..968bc5da1
--- /dev/null
+++ b/man/man5/proc_pid_oom_score_adj.5
@@ -0,0 +1,117 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_oom_score_adj 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/oom_score_adj \- OOM-killer score adjustment
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /oom_score_adj " (since Linux 2.6.36)"
+.\" Text taken from Linux 3.7 Documentation/filesystems/proc.txt
+This file can be used to adjust the badness heuristic used to select which
+process gets killed in out-of-memory conditions.
+.IP
+The badness heuristic assigns a value to each candidate task ranging from 0
+(never kill) to 1000 (always kill) to determine which process is targeted.
+The units are roughly a proportion along that range of
+allowed memory the process may allocate from,
+based on an estimation of its current memory and swap use.
+For example, if a task is using all allowed memory,
+its badness score will be 1000.
+If it is using half of its allowed memory, its score will be 500.
+.IP
+There is an additional factor included in the badness score: root
+processes are given 3% extra memory over other tasks.
+.IP
+The amount of "allowed" memory depends on the context
+in which the OOM-killer was called.
+If it is due to the memory assigned to the allocating task's cpuset
+being exhausted,
+the allowed memory represents the set of mems assigned to that
+cpuset (see
+.BR cpuset (7)).
+If it is due to a mempolicy's node(s) being exhausted,
+the allowed memory represents the set of mempolicy nodes.
+If it is due to a memory limit (or swap limit) being reached,
+the allowed memory is that configured limit.
+Finally, if it is due to the entire system being out of memory, the
+allowed memory represents all allocatable resources.
+.IP
+The value of
+.I oom_score_adj
+is added to the badness score before it
+is used to determine which task to kill.
+Acceptable values range from \-1000
+(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX).
+This allows user space to control the preference for OOM-killing,
+ranging from always preferring a certain
+task or completely disabling it from OOM-killing.
+The lowest possible value, \-1000, is
+equivalent to disabling OOM-killing entirely for that task,
+since it will always report a badness score of 0.
+.IP
+Consequently, it is very simple for user space to define
+the amount of memory to consider for each task.
+Setting an
+.I oom_score_adj
+value of +500, for example,
+is roughly equivalent to allowing the remainder of tasks sharing the
+same system, cpuset, mempolicy, or memory controller resources
+to use at least 50% more memory.
+A value of \-500, on the other hand, would be roughly
+equivalent to discounting 50% of the task's
+allowed memory from being considered as scoring against the task.
+.IP
+For backward compatibility with previous kernels,
+.IR /proc/ pid /oom_adj
+can still be used to tune the badness score.
+Its value is
+scaled linearly with
+.IR oom_score_adj .
+.IP
+Writing to
+.IR /proc/ pid /oom_score_adj
+or
+.IR /proc/ pid /oom_adj
+will change the other with its scaled value.
+.IP
+The
+.BR choom (1)
+program provides a command-line interface for adjusting the
+.I oom_score_adj
+value of a running process or a newly executed command.
+.SH HISTORY
+.TP
+.IR /proc/ pid /oom_adj " (since Linux 2.6.11)"
+This file can be used to adjust the score used to select which process
+should be killed in an out-of-memory (OOM) situation.
+The kernel uses this value for a bit-shift operation of the process's
+.I oom_score
+value:
+valid values are in the range \-16 to +15,
+plus the special value \-17,
+which disables OOM-killing altogether for this process.
+A positive score increases the likelihood of this
+process being killed by the OOM-killer;
+a negative score decreases the likelihood.
+.IP
+The default value for this file is 0;
+a new process inherits its parent's
+.I oom_adj
+setting.
+A process must be privileged
+.RB ( CAP_SYS_RESOURCE )
+to update this file,
+although a process can always increase its own
+.I oom_adj
+setting (since Linux 2.6.20).
+.IP
+Since Linux 2.6.36, use of this file is deprecated in favor of
+.IR /proc/ pid /oom_score_adj ,
+and finally removed in Linux 3.7.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_pid_oom_score (5)
diff --git a/man/man5/proc_pid_pagemap.5 b/man/man5/proc_pid_pagemap.5
new file mode 100644
index 000000000..d68c56d6a
--- /dev/null
+++ b/man/man5/proc_pid_pagemap.5
@@ -0,0 +1,77 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_pagemap 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/pagemap \- mapping of virtual pages
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /pagemap " (since Linux 2.6.25)"
+This file shows the mapping of each of the process's virtual pages
+into physical page frames or swap area.
+It contains one 64-bit value for each virtual page,
+with the bits set as follows:
+.RS
+.TP
+63
+If set, the page is present in RAM.
+.TP
+62
+If set, the page is in swap space
+.TP
+61 (since Linux 3.5)
+The page is a file-mapped page or a shared anonymous page.
+.TP
+60\[en]58 (since Linux 3.11)
+Zero
+.\" Not quite true; see commit 541c237c0923f567c9c4cabb8a81635baadc713f
+.TP
+57 (since Linux 5.14)
+If set, the page is write-protected through
+.BR userfaultfd (2).
+.TP
+56 (since Linux 4.2)
+.\" commit 77bb499bb60f4b79cca7d139c8041662860fcf87
+.\" commit 83b4b0bb635eee2b8e075062e4e008d1bc110ed7
+The page is exclusively mapped.
+.TP
+55 (since Linux 3.11)
+PTE is soft-dirty
+(see the kernel source file
+.IR Documentation/admin\-guide/mm/soft\-dirty.rst ).
+.TP
+54\[en]0
+If the page is present in RAM (bit 63), then these bits
+provide the page frame number, which can be used to index
+.I /proc/kpageflags
+and
+.IR /proc/kpagecount .
+If the page is present in swap (bit 62),
+then bits 4\[en]0 give the swap type, and bits 54\[en]5 encode the swap offset.
+.RE
+.IP
+Before Linux 3.11, bits 60\[en]55 were
+used to encode the base-2 log of the page size.
+.IP
+To employ
+.IR /proc/ pid /pagemap
+efficiently, use
+.IR /proc/ pid /maps
+to determine which areas of memory are actually mapped and seek
+to skip over unmapped regions.
+.IP
+The
+.IR /proc/ pid /pagemap
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_personality.5 b/man/man5/proc_pid_personality.5
new file mode 100644
index 000000000..49b8f5fdf
--- /dev/null
+++ b/man/man5/proc_pid_personality.5
@@ -0,0 +1,23 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_personality 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/personality \- execution domain
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /personality " (since Linux 2.6.28)"
+.\" commit 478307230810d7e2a753ed220db9066dfdf88718
+This read-only file exposes the process's execution domain, as set by
+.BR personality (2).
+The value is displayed in hexadecimal notation.
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_projid_map.5 b/man/man5/proc_pid_projid_map.5
new file mode 100644
index 000000000..84ede67b5
--- /dev/null
+++ b/man/man5/proc_pid_projid_map.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_projid_map 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/projid_map \- project ID mappings
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /projid_map " (since Linux 3.7)"
+.\"       commit f76d207a66c3a53defea67e7d36c3eb1b7d6d61d
+See
+.BR user_namespaces (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_root.5 b/man/man5/proc_pid_root.5
new file mode 100644
index 000000000..7a2850ca4
--- /dev/null
+++ b/man/man5/proc_pid_root.5
@@ -0,0 +1,75 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_root 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/root/ \- symbolic link to root directory
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /root/
+UNIX and Linux support the idea of a per-process root of the
+filesystem, set by the
+.BR chroot (2)
+system call.
+This file is a symbolic link that points to the process's
+root directory, and behaves in the same way as
+.IR exe ,
+and
+.IR fd/* .
+.IP
+Note however that this file is not merely a symbolic link.
+It provides the same view of the filesystem (including namespaces and the
+set of per-process mounts) as the process itself.
+An example illustrates this point.
+In one terminal, we start a shell in new user and mount namespaces,
+and in that shell we create some new mounts:
+.IP
+.in +4n
+.EX
+$ \fBPS1=\[aq]sh1# \[aq] unshare \-Urnm\fP
+sh1# \fBmount \-t tmpfs tmpfs /etc\fP  # Mount empty tmpfs at /etc
+sh1# \fBmount \-\-bind /usr /dev\fP     # Mount /usr at /dev
+sh1# \fBecho $$\fP
+27123
+.EE
+.in
+.IP
+In a second terminal window, in the initial mount namespace,
+we look at the contents of the corresponding mounts in
+the initial and new namespaces:
+.IP
+.in +4n
+.EX
+$ \fBPS1=\[aq]sh2# \[aq] sudo sh\fP
+sh2# \fBls /etc | wc \-l\fP                  # In initial NS
+309
+sh2# \fBls /proc/27123/root/etc | wc \-l\fP  # /etc in other NS
+0                                     # The empty tmpfs dir
+sh2# \fBls /dev | wc \-l\fP                  # In initial NS
+205
+sh2# \fBls /proc/27123/root/dev | wc \-l\fP  # /dev in other NS
+11                                    # Actually bind
+                                      # mounted to /usr
+sh2# \fBls /usr | wc \-l\fP                  # /usr in initial NS
+11
+.EE
+.in
+.IP
+.\" The following was still true as at kernel 2.6.13
+In a multithreaded process, the contents of the
+.IR /proc/ pid /root
+symbolic link are not available if the main thread has already terminated
+(typically by calling
+.BR pthread_exit (3)).
+.IP
+Permission to dereference or read
+.RB ( readlink (2))
+this symbolic link is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_seccomp.5 b/man/man5/proc_pid_seccomp.5
new file mode 100644
index 000000000..2002c45ed
--- /dev/null
+++ b/man/man5/proc_pid_seccomp.5
@@ -0,0 +1,36 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_seccomp 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/seccomp \- secure computing mode
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /seccomp " (Linux 2.6.12 to Linux 2.6.22)"
+This file can be used to read and change the process's
+secure computing (seccomp) mode setting.
+It contains the value 0 if the process is not in seccomp mode,
+and 1 if the process is in strict seccomp mode (see
+.BR seccomp (2)).
+Writing 1 to this file places the process irreversibly in strict seccomp mode.
+(Further attempts to write to the file fail with the
+.B EPERM
+error.)
+.IP
+In Linux 2.6.23,
+this file went away, to be replaced by the
+.BR prctl (2)
+.B PR_GET_SECCOMP
+and
+.B PR_SET_SECCOMP
+operations (and later by
+.BR seccomp (2)
+and the
+.I Seccomp
+field in
+.IR /proc/ pid /status ).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_setgroups.5 b/man/man5/proc_pid_setgroups.5
new file mode 100644
index 000000000..8d3be35c2
--- /dev/null
+++ b/man/man5/proc_pid_setgroups.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_setgroups 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/setgroups \- allow or deny setting groups
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /setgroups " (since Linux 3.19)"
+See
+.BR user_namespaces (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_smaps.5 b/man/man5/proc_pid_smaps.5
new file mode 100644
index 000000000..b029fcf1b
--- /dev/null
+++ b/man/man5/proc_pid_smaps.5
@@ -0,0 +1,129 @@
+'\" t
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_smaps 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/smaps \- XXX: What does 's' in "smaps" stand for?
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /smaps " (since Linux 2.6.14)"
+This file shows memory consumption for each of the process's mappings.
+(The
+.BR pmap (1)
+command displays similar information,
+in a form that may be easier for parsing.)
+For each mapping there is a series of lines such as the following:
+.IP
+.in +4n
+.EX
+00400000\-0048a000 r\-xp 00000000 fd:03 960637       /bin/bash
+Size:                552 kB
+Rss:                 460 kB
+Pss:                 100 kB
+Shared_Clean:        452 kB
+Shared_Dirty:          0 kB
+Private_Clean:         8 kB
+Private_Dirty:         0 kB
+Referenced:          460 kB
+Anonymous:             0 kB
+AnonHugePages:         0 kB
+ShmemHugePages:        0 kB
+ShmemPmdMapped:        0 kB
+Swap:                  0 kB
+KernelPageSize:        4 kB
+MMUPageSize:           4 kB
+Locked:                0 kB
+ProtectionKey:         0
+VmFlags: rd ex mr mw me dw
+.EE
+.in
+.IP
+The first of these lines shows the same information as is displayed
+for the mapping in
+.IR /proc/ pid /maps .
+The following lines show the size of the mapping,
+the amount of the mapping that is currently resident in RAM ("Rss"),
+the process's proportional share of this mapping ("Pss"),
+the number of clean and dirty shared pages in the mapping,
+and the number of clean and dirty private pages in the mapping.
+"Referenced" indicates the amount of memory currently marked as
+referenced or accessed.
+"Anonymous" shows the amount of memory
+that does not belong to any file.
+"Swap" shows how much
+would-be-anonymous memory is also used, but out on swap.
+.IP
+The "KernelPageSize" line (available since Linux 2.6.29)
+is the page size used by the kernel to back the virtual memory area.
+This matches the size used by the MMU in the majority of cases.
+However, one counter-example occurs on PPC64 kernels
+whereby a kernel using 64 kB as a base page size may still use 4 kB
+pages for the MMU on older processors.
+To distinguish the two attributes, the "MMUPageSize" line
+(also available since Linux 2.6.29)
+reports the page size used by the MMU.
+.IP
+The "Locked" indicates whether the mapping is locked in memory
+or not.
+.IP
+The "ProtectionKey" line (available since Linux 4.9, on x86 only)
+contains the memory protection key (see
+.BR pkeys (7))
+associated with the virtual memory area.
+This entry is present only if the kernel was built with the
+.B CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+configuration option (since Linux 4.6).
+.IP
+The "VmFlags" line (available since Linux 3.8)
+represents the kernel flags associated with the virtual memory area,
+encoded using the following two-letter codes:
+.RS
+.IP
+.TS
+l l l.
+rd	-	readable
+wr	-	writable
+ex	-	executable
+sh	-	shared
+mr	-	may read
+mw	-	may write
+me	-	may execute
+ms	-	may share
+gd	-	stack segment grows down
+pf	-	pure PFN range
+dw	-	disabled write to the mapped file
+lo	-	pages are locked in memory
+io	-	memory mapped I/O area
+sr	-	sequential read advise provided
+rr	-	random read advise provided
+dc	-	do not copy area on fork
+de	-	do not expand area on remapping
+ac	-	area is accountable
+nr	-	swap space is not reserved for the area
+ht	-	area uses huge tlb pages
+sf	-	perform synchronous page faults (since Linux 4.15)
+nl	-	non-linear mapping (removed in Linux 4.0)
+ar	-	architecture specific flag
+wf	-	wipe on fork (since Linux 4.14)
+dd	-	do not include area into core dump
+sd	-	soft-dirty flag (since Linux 3.13)
+mm	-	mixed map area
+hg	-	huge page advise flag
+nh	-	no-huge page advise flag
+mg	-	mergeable advise flag
+um	-	userfaultfd missing pages tracking (since Linux 4.3)
+uw	-	userfaultfd wprotect pages tracking (since Linux 4.3)
+.TE
+.RE
+.IP
+The
+.IR /proc/ pid /smaps
+file is present only if the
+.B CONFIG_PROC_PAGE_MONITOR
+kernel configuration option is enabled.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_stack.5 b/man/man5/proc_pid_stack.5
new file mode 100644
index 000000000..7651e997e
--- /dev/null
+++ b/man/man5/proc_pid_stack.5
@@ -0,0 +1,25 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_stack 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/stack \- kernel stack
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /stack " (since Linux 2.6.29)"
+.\" 2ec220e27f5040aec1e88901c1b6ea3d135787ad
+This file provides a symbolic trace of the function calls in this
+process's kernel stack.
+This file is provided only if the kernel was built with the
+.B CONFIG_STACKTRACE
+configuration option.
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_stat.5 b/man/man5/proc_pid_stat.5
new file mode 100644
index 000000000..b2ee991d8
--- /dev/null
+++ b/man/man5/proc_pid_stat.5
@@ -0,0 +1,380 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_stat 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/stat \- status information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /stat
+Status information about the process.
+This is used by
+.BR ps (1).
+It is defined in the kernel source file
+.IR fs/proc/array.c "."
+.IP
+The fields, in order, with their proper
+.BR scanf (3)
+format specifiers, are listed below.
+Whether or not certain of these fields display valid information is governed by
+a ptrace access mode
+.BR PTRACE_MODE_READ_FSCREDS " | " PTRACE_MODE_NOAUDIT
+check (refer to
+.BR ptrace (2)).
+If the check denies access, then the field value is displayed as 0.
+The affected fields are indicated with the marking [PT].
+.RS
+.TP
+(1) \fIpid\fP \ %d
+.br
+The process ID.
+.TP
+(2) \fIcomm\fP \ %s
+The filename of the executable, in parentheses.
+Strings longer than
+.B TASK_COMM_LEN
+(16) characters (including the terminating null byte) are silently truncated.
+This is visible whether or not the executable is swapped out.
+.TP
+(3) \fIstate\fP \ %c
+One of the following characters, indicating process state:
+.RS
+.TP
+R
+Running
+.TP
+S
+Sleeping in an interruptible wait
+.TP
+D
+Waiting in uninterruptible
+disk sleep
+.TP
+Z
+Zombie
+.TP
+T
+Stopped (on a signal) or (before Linux 2.6.33) trace stopped
+.TP
+t
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Tracing stop (Linux 2.6.33 onward)
+.TP
+W
+Paging (only before Linux 2.6.0)
+.TP
+X
+Dead (from Linux 2.6.0 onward)
+.TP
+x
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Dead (Linux 2.6.33 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.TP
+K
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Wakekill (Linux 2.6.33 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.TP
+W
+.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29
+Waking (Linux 2.6.33 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.TP
+P
+.\" commit f2530dc71cf0822f90bb63ea4600caaef33a66bb
+Parked (Linux 3.9 to
+.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457
+3.13 only)
+.TP
+I
+.\" commit 06eb61844d841d0032a9950ce7f8e783ee49c0d0
+Idle (Linux 4.14 onward)
+.RE
+.TP
+(4) \fIppid\fP \ %d
+The PID of the parent of this process.
+.TP
+(5) \fIpgrp\fP \ %d
+The process group ID of the process.
+.TP
+(6) \fIsession\fP \ %d
+The session ID of the process.
+.TP
+(7) \fItty_nr\fP \ %d
+The controlling terminal of the process.
+(The minor device number is contained in the combination of bits
+31 to 20 and 7 to 0;
+the major device number is in bits 15 to 8.)
+.TP
+(8) \fItpgid\fP \ %d
+.\" This field and following, up to and including wchan added 0.99.1
+The ID of the foreground process group of the controlling
+terminal of the process.
+.TP
+(9) \fIflags\fP \ %u
+The kernel flags word of the process.
+For bit meanings,
+see the PF_* defines in the Linux kernel source file
+.IR include/linux/sched.h .
+Details depend on the kernel version.
+.IP
+The format for this field was %lu before Linux 2.6.
+.TP
+(10) \fIminflt\fP \ %lu
+The number of minor faults the process has made which have not
+required loading a memory page from disk.
+.TP
+(11) \fIcminflt\fP \ %lu
+The number of minor faults that the process's
+waited-for children have made.
+.TP
+(12) \fImajflt\fP \ %lu
+The number of major faults the process has made which have
+required loading a memory page from disk.
+.TP
+(13) \fIcmajflt\fP \ %lu
+The number of major faults that the process's
+waited-for children have made.
+.TP
+(14) \fIutime\fP \ %lu
+Amount of time that this process has been scheduled in user mode,
+measured in clock ticks (divide by
+.IR sysconf(_SC_CLK_TCK) ).
+This includes guest time, \fIguest_time\fP
+(time spent running a virtual CPU, see below),
+so that applications that are not aware of the guest time field
+do not lose that time from their calculations.
+.TP
+(15) \fIstime\fP \ %lu
+Amount of time that this process has been scheduled in kernel mode,
+measured in clock ticks (divide by
+.IR sysconf(_SC_CLK_TCK) ).
+.TP
+(16) \fIcutime\fP \ %ld
+Amount of time that this process's
+waited-for children have been scheduled in user mode,
+measured in clock ticks (divide by
+.IR sysconf(_SC_CLK_TCK) ).
+(See also
+.BR times (2).)
+This includes guest time, \fIcguest_time\fP
+(time spent running a virtual CPU, see below).
+.TP
+(17) \fIcstime\fP \ %ld
+Amount of time that this process's
+waited-for children have been scheduled in kernel mode,
+measured in clock ticks (divide by
+.IR sysconf(_SC_CLK_TCK) ).
+.TP
+(18) \fIpriority\fP \ %ld
+(Explanation for Linux 2.6)
+For processes running a real-time scheduling policy
+.RI ( policy
+below; see
+.BR sched_setscheduler (2)),
+this is the negated scheduling priority, minus one;
+that is, a number in the range \-2 to \-100,
+corresponding to real-time priorities 1 to 99.
+For processes running under a non-real-time scheduling policy,
+this is the raw nice value
+.RB ( setpriority (2))
+as represented in the kernel.
+The kernel stores nice values as numbers
+in the range 0 (high) to 39 (low),
+corresponding to the user-visible nice range of \-20 to 19.
+.IP
+Before Linux 2.6, this was a scaled value based on
+the scheduler weighting given to this process.
+.\" And back in Linux 1.2 days things were different again.
+.TP
+(19) \fInice\fP \ %ld
+The nice value (see
+.BR setpriority (2)),
+a value in the range 19 (low priority) to \-20 (high priority).
+.\" Back in Linux 1.2 days things were different.
+.\" .TP
+.\" \fIcounter\fP %ld
+.\" The current maximum size in jiffies of the process's next timeslice,
+.\" or what is currently left of its current timeslice, if it is the
+.\" currently running process.
+.\" .TP
+.\" \fItimeout\fP %u
+.\" The time in jiffies of the process's next timeout.
+.\" timeout was removed sometime around 2.1/2.2
+.TP
+(20) \fInum_threads\fP \ %ld
+Number of threads in this process (since Linux 2.6).
+Before Linux 2.6, this field was hard coded to 0 as a placeholder
+for an earlier removed field.
+.TP
+(21) \fIitrealvalue\fP \ %ld
+The time in jiffies before the next
+.B SIGALRM
+is sent to the process due to an interval timer.
+Since Linux 2.6.17, this field is no longer maintained,
+and is hard coded as 0.
+.TP
+(22) \fIstarttime\fP \ %llu
+The time the process started after system boot.
+Before Linux 2.6, this value was expressed in jiffies.
+Since Linux 2.6, the value is expressed in clock ticks (divide by
+.IR sysconf(_SC_CLK_TCK) ).
+.IP
+The format for this field was %lu before Linux 2.6.
+.TP
+(23) \fIvsize\fP \ %lu
+Virtual memory size in bytes.
+.TP
+(24) \fIrss\fP \ %ld
+Resident Set Size: number of pages the process has in real memory.
+This is just the pages which
+count toward text, data, or stack space.
+This does not include pages
+which have not been demand-loaded in, or which are swapped out.
+This value is inaccurate; see
+.IR /proc/ pid /statm
+below.
+.TP
+(25) \fIrsslim\fP \ %lu
+Current soft limit in bytes on the rss of the process;
+see the description of
+.B RLIMIT_RSS
+in
+.BR getrlimit (2).
+.TP
+(26) \fIstartcode\fP \ %lu \ [PT]
+The address above which program text can run.
+.TP
+(27) \fIendcode\fP \ %lu \ [PT]
+The address below which program text can run.
+.TP
+(28) \fIstartstack\fP \ %lu \ [PT]
+The address of the start (i.e., bottom) of the stack.
+.TP
+(29) \fIkstkesp\fP \ %lu \ [PT]
+The current value of ESP (stack pointer), as found in the
+kernel stack page for the process.
+.TP
+(30) \fIkstkeip\fP \ %lu \ [PT]
+The current EIP (instruction pointer).
+.TP
+(31) \fIsignal\fP \ %lu
+The bitmap of pending signals, displayed as a decimal number.
+Obsolete, because it does not provide information on real-time signals; use
+.IR /proc/ pid /status
+instead.
+.TP
+(32) \fIblocked\fP \ %lu
+The bitmap of blocked signals, displayed as a decimal number.
+Obsolete, because it does not provide information on real-time signals; use
+.IR /proc/ pid /status
+instead.
+.TP
+(33) \fIsigignore\fP \ %lu
+The bitmap of ignored signals, displayed as a decimal number.
+Obsolete, because it does not provide information on real-time signals; use
+.IR /proc/ pid /status
+instead.
+.TP
+(34) \fIsigcatch\fP \ %lu
+The bitmap of caught signals, displayed as a decimal number.
+Obsolete, because it does not provide information on real-time signals; use
+.IR /proc/ pid /status
+instead.
+.TP
+(35) \fIwchan\fP \ %lu \ [PT]
+This is the "channel" in which the process is waiting.
+It is the address of a location in the kernel where the process is sleeping.
+The corresponding symbolic name can be found in
+.IR /proc/ pid /wchan .
+.TP
+(36) \fInswap\fP \ %lu
+.\" nswap was added in Linux 2.0
+Number of pages swapped (not maintained).
+.TP
+(37) \fIcnswap\fP \ %lu
+.\" cnswap was added in Linux 2.0
+Cumulative \fInswap\fP for child processes (not maintained).
+.TP
+(38) \fIexit_signal\fP \ %d \ (since Linux 2.1.22)
+Signal to be sent to parent when we die.
+.TP
+(39) \fIprocessor\fP \ %d \ (since Linux 2.2.8)
+CPU number last executed on.
+.TP
+(40) \fIrt_priority\fP \ %u \ (since Linux 2.5.19)
+Real-time scheduling priority, a number in the range 1 to 99 for
+processes scheduled under a real-time policy,
+or 0, for non-real-time processes (see
+.BR sched_setscheduler (2)).
+.TP
+(41) \fIpolicy\fP \ %u \ (since Linux 2.5.19)
+Scheduling policy (see
+.BR sched_setscheduler (2)).
+Decode using the SCHED_* constants in
+.IR linux/sched.h .
+.IP
+The format for this field was %lu before Linux 2.6.22.
+.TP
+(42) \fIdelayacct_blkio_ticks\fP \ %llu \ (since Linux 2.6.18)
+Aggregated block I/O delays, measured in clock ticks (centiseconds).
+.TP
+(43) \fIguest_time\fP \ %lu \ (since Linux 2.6.24)
+Guest time of the process (time spent running a virtual CPU
+for a guest operating system), measured in clock ticks (divide by
+.IR sysconf(_SC_CLK_TCK) ).
+.TP
+(44) \fIcguest_time\fP \ %ld \ (since Linux 2.6.24)
+Guest time of the process's children, measured in clock ticks (divide by
+.IR sysconf(_SC_CLK_TCK) ).
+.TP
+(45) \fIstart_data\fP \ %lu \ (since Linux 3.3) \ [PT]
+.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff
+Address above which program initialized and
+uninitialized (BSS) data are placed.
+.TP
+(46) \fIend_data\fP \ %lu \ (since Linux 3.3) \ [PT]
+.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff
+Address below which program initialized and
+uninitialized (BSS) data are placed.
+.TP
+(47) \fIstart_brk\fP \ %lu \ (since Linux 3.3) \ [PT]
+.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff
+Address above which program heap can be expanded with
+.BR brk (2).
+.TP
+(48) \fIarg_start\fP \ %lu \ (since Linux 3.5) \ [PT]
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address above which program command-line arguments
+.RI ( argv )
+are placed.
+.TP
+(49) \fIarg_end\fP \ %lu \ (since Linux 3.5) \ [PT]
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address below program command-line arguments
+.RI ( argv )
+are placed.
+.TP
+(50) \fIenv_start\fP \ %lu \ (since Linux 3.5) \ [PT]
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address above which program environment is placed.
+.TP
+(51) \fIenv_end\fP \ %lu \ (since Linux 3.5) \ [PT]
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+Address below which program environment is placed.
+.TP
+(52) \fIexit_code\fP \ %d \ (since Linux 3.5) \ [PT]
+.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3
+The thread's exit status in the form reported by
+.BR waitpid (2).
+.RE
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_pid_status (5)
diff --git a/man/man5/proc_pid_statm.5 b/man/man5/proc_pid_statm.5
new file mode 100644
index 000000000..1d0045a53
--- /dev/null
+++ b/man/man5/proc_pid_statm.5
@@ -0,0 +1,46 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_statm 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/statm \- memory usage information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /statm
+Provides information about memory usage, measured in pages.
+The columns are:
+.IP
+.in +4n
+.EX
+size       (1) total program size
+           (same as VmSize in \fI/proc/\fPpid\fI/status\fP)
+resident   (2) resident set size
+           (inaccurate; same as VmRSS in \fI/proc/\fPpid\fI/status\fP)
+shared     (3) number of resident shared pages
+           (i.e., backed by a file)
+           (inaccurate; same as RssFile+RssShmem in
+           \fI/proc/\fPpid\fI/status\fP)
+text       (4) text (code)
+.\" (not including libs; broken, includes data segment)
+lib        (5) library (unused since Linux 2.6; always 0)
+data       (6) data + stack
+.\" (including libs; broken, includes library text)
+dt         (7) dirty pages (unused since Linux 2.6; always 0)
+.EE
+.in
+.IP
+.\" See SPLIT_RSS_COUNTING in the kernel.
+.\" Inaccuracy is bounded by TASK_RSS_EVENTS_THRESH.
+Some of these values are inaccurate because
+of a kernel-internal scalability optimization.
+If accurate values are required, use
+.IR /proc/ pid /smaps
+or
+.IR /proc/ pid /smaps_rollup
+instead, which are much slower but provide accurate, detailed information.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_pid_status (5)
diff --git a/man/man5/proc_pid_status.5 b/man/man5/proc_pid_status.5
new file mode 100644
index 000000000..65a75546e
--- /dev/null
+++ b/man/man5/proc_pid_status.5
@@ -0,0 +1,384 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_status 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/status \- memory usage and status information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /status
+Provides much of the information in
+.IR /proc/ pid /stat
+and
+.IR /proc/ pid /statm
+in a format that's easier for humans to parse.
+Here's an example:
+.IP
+.in +4n
+.EX
+.RB "$" " cat /proc/$$/status"
+Name:   bash
+Umask:  0022
+State:  S (sleeping)
+Tgid:   17248
+Ngid:   0
+Pid:    17248
+PPid:   17200
+TracerPid:      0
+Uid:    1000    1000    1000    1000
+Gid:    100     100     100     100
+FDSize: 256
+Groups: 16 33 100
+NStgid: 17248
+NSpid:  17248
+NSpgid: 17248
+NSsid:  17200
+VmPeak:	  131168 kB
+VmSize:	  131168 kB
+VmLck:	       0 kB
+VmPin:	       0 kB
+VmHWM:	   13484 kB
+VmRSS:	   13484 kB
+RssAnon:	   10264 kB
+RssFile:	    3220 kB
+RssShmem:	       0 kB
+VmData:	   10332 kB
+VmStk:	     136 kB
+VmExe:	     992 kB
+VmLib:	    2104 kB
+VmPTE:	      76 kB
+VmPMD:	      12 kB
+VmSwap:	       0 kB
+HugetlbPages:          0 kB		# 4.4
+CoreDumping:	0                       # 4.15
+Threads:        1
+SigQ:   0/3067
+SigPnd: 0000000000000000
+ShdPnd: 0000000000000000
+SigBlk: 0000000000010000
+SigIgn: 0000000000384004
+SigCgt: 000000004b813efb
+CapInh: 0000000000000000
+CapPrm: 0000000000000000
+CapEff: 0000000000000000
+CapBnd: ffffffffffffffff
+CapAmb:	0000000000000000
+NoNewPrivs:     0
+Seccomp:        0
+Seccomp_filters:        0
+Speculation_Store_Bypass:       vulnerable
+Cpus_allowed:   00000001
+Cpus_allowed_list:      0
+Mems_allowed:   1
+Mems_allowed_list:      0
+voluntary_ctxt_switches:        150
+nonvoluntary_ctxt_switches:     545
+.EE
+.in
+.IP
+The fields are as follows:
+.RS
+.TP
+.I Name
+Command run by this process.
+Strings longer than
+.B TASK_COMM_LEN
+(16) characters (including the terminating null byte) are silently truncated.
+.TP
+.I Umask
+Process umask, expressed in octal with a leading zero; see
+.BR umask (2).
+(Since Linux 4.7.)
+.TP
+.I State
+Current state of the process.
+One of
+"R (running)",
+"S (sleeping)",
+"D (disk sleep)",
+"T (stopped)",
+"t (tracing stop)",
+"Z (zombie)",
+or
+"X (dead)".
+.TP
+.I Tgid
+Thread group ID (i.e., Process ID).
+.TP
+.I Ngid
+NUMA group ID (0 if none; since Linux 3.13).
+.TP
+.I Pid
+Thread ID (see
+.BR gettid (2)).
+.TP
+.I PPid
+PID of parent process.
+.TP
+.I TracerPid
+PID of process tracing this process (0 if not being traced).
+.TP
+.I Uid
+.TQ
+.I Gid
+Real, effective, saved set, and filesystem UIDs (GIDs).
+.TP
+.I FDSize
+Number of file descriptor slots currently allocated.
+.TP
+.I Groups
+Supplementary group list.
+.TP
+.I NStgid
+Thread group ID (i.e., PID) in each of the PID namespaces of which
+.I pid
+is a member.
+The leftmost entry shows the value with respect to the PID namespace
+of the process that mounted this procfs (or the root namespace
+if mounted by the kernel),
+followed by the value in successively nested inner namespaces.
+.\" commit e4bc33245124db69b74a6d853ac76c2976f472d5
+(Since Linux 4.1.)
+.TP
+.I NSpid
+Thread ID in each of the PID namespaces of which
+.I pid
+is a member.
+The fields are ordered as for
+.IR NStgid .
+(Since Linux 4.1.)
+.TP
+.I NSpgid
+Process group ID in each of the PID namespaces of which
+.I pid
+is a member.
+The fields are ordered as for
+.IR NStgid .
+(Since Linux 4.1.)
+.TP
+.I NSsid
+descendant namespace session ID hierarchy
+Session ID in each of the PID namespaces of which
+.I pid
+is a member.
+The fields are ordered as for
+.IR NStgid .
+(Since Linux 4.1.)
+.TP
+.I VmPeak
+Peak virtual memory size.
+.TP
+.I VmSize
+Virtual memory size.
+.TP
+.I VmLck
+Locked memory size (see
+.BR mlock (2)).
+.TP
+.I VmPin
+Pinned memory size
+.\" commit bc3e53f682d93df677dbd5006a404722b3adfe18
+(since Linux 3.2).
+These are pages that can't be moved because something needs to
+directly access physical memory.
+.TP
+.I VmHWM
+Peak resident set size ("high water mark").
+This value is inaccurate; see
+.IR /proc/ pid /statm
+above.
+.TP
+.I VmRSS
+Resident set size.
+Note that the value here is the sum of
+.IR RssAnon ,
+.IR RssFile ,
+and
+.IR RssShmem .
+This value is inaccurate; see
+.IR /proc/ pid /statm
+above.
+.TP
+.I RssAnon
+Size of resident anonymous memory.
+.\" commit bf9683d6990589390b5178dafe8fd06808869293
+(since Linux 4.5).
+This value is inaccurate; see
+.IR /proc/ pid /statm
+above.
+.TP
+.I RssFile
+Size of resident file mappings.
+.\" commit bf9683d6990589390b5178dafe8fd06808869293
+(since Linux 4.5).
+This value is inaccurate; see
+.IR /proc/ pid /statm
+above.
+.TP
+.I RssShmem
+Size of resident shared memory (includes System V shared memory,
+mappings from
+.BR tmpfs (5),
+and shared anonymous mappings).
+.\" commit bf9683d6990589390b5178dafe8fd06808869293
+(since Linux 4.5).
+.TP
+.I VmData
+.TQ
+.I VmStk
+.TQ
+.I VmExe
+Size of data, stack, and text segments.
+This value is inaccurate; see
+.IR /proc/ pid /statm
+above.
+.TP
+.I VmLib
+Shared library code size.
+.TP
+.I VmPTE
+Page table entries size (since Linux 2.6.10).
+.TP
+.I VmPMD
+.\" commit dc6c9a35b66b520cf67e05d8ca60ebecad3b0479
+Size of second-level page tables (added in Linux 4.0; removed in Linux 4.15).
+.TP
+.I VmSwap
+.\" commit b084d4353ff99d824d3bc5a5c2c22c70b1fba722
+Swapped-out virtual memory size by anonymous private pages;
+shmem swap usage is not included (since Linux 2.6.34).
+This value is inaccurate; see
+.IR /proc/ pid /statm
+above.
+.TP
+.I HugetlbPages
+Size of hugetlb memory portions
+.\" commit 5d317b2b6536592a9b51fe65faed43d65ca9158e
+(since Linux 4.4).
+.TP
+.I CoreDumping
+Contains the value 1 if the process is currently dumping core,
+and 0 if it is not
+.\" commit c643401218be0f4ab3522e0c0a63016596d6e9ca
+(since Linux 4.15).
+This information can be used by a monitoring process to avoid killing
+a process that is currently dumping core,
+which could result in a corrupted core dump file.
+.TP
+.I Threads
+Number of threads in process containing this thread.
+.TP
+.I SigQ
+This field contains two slash-separated numbers that relate to
+queued signals for the real user ID of this process.
+The first of these is the number of currently queued
+signals for this real user ID, and the second is the
+resource limit on the number of queued signals for this process
+(see the description of
+.B RLIMIT_SIGPENDING
+in
+.BR getrlimit (2)).
+.TP
+.I SigPnd
+.TQ
+.I ShdPnd
+Mask (expressed in hexadecimal)
+of signals pending for thread and for process as a whole (see
+.BR pthreads (7)
+and
+.BR signal (7)).
+.TP
+.I SigBlk
+.TQ
+.I SigIgn
+.TQ
+.I SigCgt
+Masks (expressed in hexadecimal)
+indicating signals being blocked, ignored, and caught (see
+.BR signal (7)).
+.TP
+.I CapInh
+.TQ
+.I CapPrm
+.TQ
+.I CapEff
+Masks (expressed in hexadecimal)
+of capabilities enabled in inheritable, permitted, and effective sets
+(see
+.BR capabilities (7)).
+.TP
+.I CapBnd
+Capability bounding set, expressed in hexadecimal
+(since Linux 2.6.26, see
+.BR capabilities (7)).
+.TP
+.I CapAmb
+Ambient capability set, expressed in hexadecimal
+(since Linux 4.3, see
+.BR capabilities (7)).
+.TP
+.I NoNewPrivs
+.\" commit af884cd4a5ae62fcf5e321fecf0ec1014730353d
+Value of the
+.I no_new_privs
+bit
+(since Linux 4.10, see
+.BR prctl (2)).
+.TP
+.I Seccomp
+.\" commit 2f4b3bf6b2318cfaa177ec5a802f4d8d6afbd816
+Seccomp mode of the process
+(since Linux 3.8, see
+.BR seccomp (2)).
+0 means
+.BR SECCOMP_MODE_DISABLED ;
+1 means
+.BR SECCOMP_MODE_STRICT ;
+2 means
+.BR SECCOMP_MODE_FILTER .
+This field is provided only if the kernel was built with the
+.B CONFIG_SECCOMP
+kernel configuration option enabled.
+.TP
+.I Seccomp_filters
+.\" commit c818c03b661cd769e035e41673d5543ba2ebda64
+Number of seccomp filters attached to the process
+(since Linux 5.9, see
+.BR seccomp (2)).
+.TP
+.I Speculation_Store_Bypass
+.\" commit fae1fa0fc6cca8beee3ab8ed71d54f9a78fa3f64
+Speculation flaw mitigation state
+(since Linux 4.17, see
+.BR prctl (2)).
+.TP
+.I Cpus_allowed
+Hexadecimal mask of CPUs on which this process may run
+(since Linux 2.6.24, see
+.BR cpuset (7)).
+.TP
+.I Cpus_allowed_list
+Same as previous, but in "list format"
+(since Linux 2.6.26, see
+.BR cpuset (7)).
+.TP
+.I Mems_allowed
+Mask of memory nodes allowed to this process
+(since Linux 2.6.24, see
+.BR cpuset (7)).
+.TP
+.I Mems_allowed_list
+Same as previous, but in "list format"
+(since Linux 2.6.26, see
+.BR cpuset (7)).
+.TP
+.I voluntary_ctxt_switches
+.TQ
+.I nonvoluntary_ctxt_switches
+Number of voluntary and involuntary context switches (since Linux 2.6.23).
+.RE
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_syscall.5 b/man/man5/proc_pid_syscall.5
new file mode 100644
index 000000000..1b2aa682b
--- /dev/null
+++ b/man/man5/proc_pid_syscall.5
@@ -0,0 +1,33 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_syscall 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/syscall \- currently executed system call
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /syscall " (since Linux 2.6.27)"
+.\" commit ebcb67341fee34061430f3367f2e507e52ee051b
+This file exposes the system call number and argument registers for the
+system call currently being executed by the process,
+followed by the values of the stack pointer and program counter registers.
+The values of all six argument registers are exposed,
+although most system calls use fewer registers.
+.IP
+If the process is blocked, but not in a system call,
+then the file displays \-1 in place of the system call number,
+followed by just the values of the stack pointer and program counter.
+If process is not blocked, then the file contains just the string "running".
+.IP
+This file is present only if the kernel was configured with
+.BR CONFIG_HAVE_ARCH_TRACEHOOK .
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_task.5 b/man/man5/proc_pid_task.5
new file mode 100644
index 000000000..808191775
--- /dev/null
+++ b/man/man5/proc_pid_task.5
@@ -0,0 +1,97 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_task 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/task/, /proc/tid/, /proc/thread\-self/ \- thread information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /task/ " (since Linux 2.6.0)"
+.\" Precisely: Linux 2.6.0-test6
+This is a directory that contains one subdirectory
+for each thread in the process.
+The name of each subdirectory is the numerical thread ID
+.RI ( tid )
+of the thread (see
+.BR gettid (2)).
+.IP
+Within each of these subdirectories, there is a set of
+files with the same names and contents as under the
+.IR /proc/ pid
+directories.
+For attributes that are shared by all threads, the contents for
+each of the files under the
+.IR task/ tid
+subdirectories will be the same as in the corresponding
+file in the parent
+.IR /proc/ pid
+directory
+(e.g., in a multithreaded process, all of the
+.IR task/ tid /cwd
+files will have the same value as the
+.IR /proc/ pid /cwd
+file in the parent directory, since all of the threads in a process
+share a working directory).
+For attributes that are distinct for each thread,
+the corresponding files under
+.IR task/ tid
+may have different values (e.g., various fields in each of the
+.IR task/ tid /status
+files may be different for each thread),
+.\" in particular: "children" :/
+or they might not exist in
+.IR /proc/ pid
+at all.
+.IP
+.\" The following was still true as at kernel 2.6.13
+In a multithreaded process, the contents of the
+.IR /proc/ pid /task
+directory are not available if the main thread has already terminated
+(typically by calling
+.BR pthread_exit (3)).
+.TP
+.IR /proc/ tid /
+There  is a numerical subdirectory for each running thread
+that is not a thread group leader
+(i.e., a thread whose thread ID is not the same as its process ID);
+the subdirectory is named by the thread ID.
+Each one of these subdirectories contains files and subdirectories
+exposing information about the thread with the thread ID
+.IR tid .
+The contents of these directories are the same as the corresponding
+.IR /proc/ pid /task/ tid
+directories.
+.IP
+The
+.IR /proc/ tid
+subdirectories are
+.I not
+visible when iterating through
+.I /proc
+with
+.BR getdents (2)
+(and thus are
+.I not
+visible when one uses
+.BR ls (1)
+to view the contents of
+.IR /proc ).
+However, the pathnames of these directories are visible to
+(i.e., usable as arguments in)
+system calls that operate on pathnames.
+.TP
+.IR /proc/thread\-self/ " (since Linux 3.17)"
+.\" commit 0097875bd41528922fb3bb5f348c53f17e00e2fd
+This directory refers to the thread accessing the
+.I /proc
+filesystem,
+and is identical to the
+.IR /proc/self/task/ tid
+directory named by the process thread ID
+.RI ( tid )
+of the same thread.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_timers.5 b/man/man5/proc_pid_timers.5
new file mode 100644
index 000000000..53f6339dc
--- /dev/null
+++ b/man/man5/proc_pid_timers.5
@@ -0,0 +1,82 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_timers 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/timers \- POSIX timers
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /timers " (since Linux 3.10)"
+.\" commit 5ed67f05f66c41e39880a6d61358438a25f9fee5
+.\" commit 48f6a7a511ef8823fdff39afee0320092d43a8a0
+A list of the POSIX timers for this process.
+Each timer is listed with a line that starts with the string "ID:".
+For example:
+.IP
+.in +4n
+.EX
+ID: 1
+signal: 60/00007fff86e452a8
+notify: signal/pid.2634
+ClockID: 0
+ID: 0
+signal: 60/00007fff86e452a8
+notify: signal/pid.2634
+ClockID: 1
+.EE
+.in
+.IP
+The lines shown for each timer have the following meanings:
+.RS
+.TP
+.I ID
+The ID for this timer.
+This is not the same as the timer ID returned by
+.BR timer_create (2);
+rather, it is the same kernel-internal ID that is available via the
+.I si_timerid
+field of the
+.I siginfo_t
+structure (see
+.BR sigaction (2)).
+.TP
+.I signal
+This is the signal number that this timer uses to deliver notifications
+followed by a slash, and then the
+.I sigev_value
+value supplied to the signal handler.
+Valid only for timers that notify via a signal.
+.TP
+.I notify
+The part before the slash specifies the mechanism
+that this timer uses to deliver notifications,
+and is one of "thread", "signal", or "none".
+Immediately following the slash is either the string "tid" for timers
+with
+.B SIGEV_THREAD_ID
+notification, or "pid" for timers that notify by other mechanisms.
+Following the "." is the PID of the process
+(or the kernel thread ID of the thread)  that will be delivered
+a signal if the timer delivers notifications via a signal.
+.TP
+.I ClockID
+This field identifies the clock that the timer uses for measuring time.
+For most clocks, this is a number that matches one of the user-space
+.B CLOCK_*
+constants exposed via
+.IR <time.h> .
+.B CLOCK_PROCESS_CPUTIME_ID
+timers display with a value of \-6
+in this field.
+.B CLOCK_THREAD_CPUTIME_ID
+timers display with a value of \-2
+in this field.
+.RE
+.IP
+This file is available only when the kernel was configured with
+.BR CONFIG_CHECKPOINT_RESTORE .
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_timerslack_ns.5 b/man/man5/proc_pid_timerslack_ns.5
new file mode 100644
index 000000000..73673faca
--- /dev/null
+++ b/man/man5/proc_pid_timerslack_ns.5
@@ -0,0 +1,41 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_timerslack_ns 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/timerslack_ns \- timer slack in nanoseconds
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /timerslack_ns " (since Linux 4.6)"
+.\" commit da8b44d5a9f8bf26da637b7336508ca534d6b319
+.\" commit 5de23d435e88996b1efe0e2cebe242074ce67c9e
+This file exposes the process's "current" timer slack value,
+expressed in nanoseconds.
+The file is writable,
+allowing the process's timer slack value to be changed.
+Writing 0 to this file resets the "current" timer slack to the
+"default" timer slack value.
+For further details, see the discussion of
+.B PR_SET_TIMERSLACK
+in
+.BR prctl (2).
+.IP
+Initially,
+permission to access this file was governed by a ptrace access mode
+.B PTRACE_MODE_ATTACH_FSCREDS
+check (see
+.BR ptrace (2)).
+However, this was subsequently deemed too strict a requirement
+(and had the side effect that requiring a process to have the
+.B CAP_SYS_PTRACE
+capability would also allow it to view and change any process's memory).
+Therefore, since Linux 4.9,
+.\" commit 7abbaf94049914f074306d960b0f968ffe52e59f
+only the (weaker)
+.B CAP_SYS_NICE
+capability is required to access this file.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_uid_map.5 b/man/man5/proc_pid_uid_map.5
new file mode 100644
index 000000000..e514eda33
--- /dev/null
+++ b/man/man5/proc_pid_uid_map.5
@@ -0,0 +1,20 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_uid_map 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/gid_map, /proc/pid/uid_map \- user and group ID mappings
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /gid_map " (since Linux 3.5)"
+See
+.BR user_namespaces (7).
+.TP
+.IR /proc/ pid /uid_map " (since Linux 3.5)"
+See
+.BR user_namespaces (7).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_pid_wchan.5 b/man/man5/proc_pid_wchan.5
new file mode 100644
index 000000000..e425e4da4
--- /dev/null
+++ b/man/man5/proc_pid_wchan.5
@@ -0,0 +1,21 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_wchan 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/pid/wchan \- wait channel
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /wchan " (since Linux 2.6.0)"
+The symbolic name corresponding to the location
+in the kernel where the process is sleeping.
+.IP
+Permission to access this file is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_profile.5 b/man/man5/proc_profile.5
new file mode 100644
index 000000000..994a4d888
--- /dev/null
+++ b/man/man5/proc_profile.5
@@ -0,0 +1,24 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_profile 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/profile \- kernel profiling
+.SH DESCRIPTION
+.TP
+.IR /proc/profile " (since Linux 2.4)"
+This file is present only if the kernel was booted with the
+.I profile=1
+command-line option.
+It exposes kernel profiling information in a binary format for use by
+.BR readprofile (1).
+Writing (e.g., an empty string) to this file resets the profiling counters;
+on some architectures,
+writing a binary integer "profiling multiplier" of size
+.I sizeof(int)
+sets the profiling interrupt frequency.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_scsi.5 b/man/man5/proc_scsi.5
new file mode 100644
index 000000000..7eb2ae3d5
--- /dev/null
+++ b/man/man5/proc_scsi.5
@@ -0,0 +1,66 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Michael Neuffer <neuffer@mail.uni-mainz.de>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_scsi 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/scsi/ \- SCSI
+.SH DESCRIPTION
+.TP
+.I /proc/scsi/
+A directory with the
+.I scsi
+mid-level pseudo-file and various SCSI low-level
+driver directories,
+which contain a file for each SCSI host in this system, all of
+which give the status of some part of the SCSI IO subsystem.
+These files contain ASCII structures and are, therefore, readable with
+.BR cat (1).
+.IP
+You can also write to some of the files to reconfigure the subsystem or
+switch certain features on or off.
+.TP
+.I /proc/scsi/scsi
+This is a listing of all SCSI devices known to the kernel.
+The listing is similar to the one seen during bootup.
+scsi currently supports only the \fIadd\-single\-device\fP command which
+allows root to add a hotplugged device to the list of known devices.
+.IP
+The command
+.IP
+.in +4n
+.EX
+echo \[aq]scsi add\-single\-device 1 0 5 0\[aq] > /proc/scsi/scsi
+.EE
+.in
+.IP
+will cause
+host scsi1 to scan on SCSI channel 0 for a device on ID 5 LUN 0.
+If there
+is already a device known on this address or the address is invalid, an
+error will be returned.
+.TP
+.IR /proc/scsi/ drivername /
+\fIdrivername\fP can currently be NCR53c7xx, aha152x, aha1542, aha1740,
+aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000, pas16, qlogic,
+scsi_debug, seagate, t128, u15\-24f, ultrastore, or wd7000.
+These directories show up for all drivers that registered at least one
+SCSI HBA.
+Every directory contains one file per registered host.
+Every host-file is named after the number the host was assigned during
+initialization.
+.IP
+Reading these files will usually show driver and host configuration,
+statistics, and so on.
+.IP
+Writing to these files allows different things on different hosts.
+For example, with the \fIlatency\fP and \fInolatency\fP commands,
+root can switch on and off command latency measurement code in the
+eata_dma driver.
+With the \fIlockup\fP and \fIunlock\fP commands,
+root can control bus lockups simulated by the scsi_debug driver.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_self.5 b/man/man5/proc_self.5
new file mode 100644
index 000000000..fb0183500
--- /dev/null
+++ b/man/man5/proc_self.5
@@ -0,0 +1 @@
+.so man5/proc_pid.5
diff --git a/man/man5/proc_slabinfo.5 b/man/man5/proc_slabinfo.5
new file mode 100644
index 000000000..a633840e0
--- /dev/null
+++ b/man/man5/proc_slabinfo.5
@@ -0,0 +1,18 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_slabinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/slabinfo \- kernel caches
+.SH DESCRIPTION
+.TP
+.I /proc/slabinfo
+Information about kernel caches.
+See
+.BR slabinfo (5)
+for details.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_stat.5 b/man/man5/proc_stat.5
new file mode 100644
index 000000000..cc5dfd575
--- /dev/null
+++ b/man/man5/proc_stat.5
@@ -0,0 +1,140 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_stat 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/stat \- kernel system statistics
+.SH DESCRIPTION
+.TP
+.I /proc/stat
+kernel/system statistics.
+Varies with architecture.
+Common
+entries include:
+.RS
+.TP
+.I cpu  10132153 290696 3084719 46828483 16683 0 25195 0 175628 0
+.TQ
+.I cpu0 1393280 32966 572056 13343292 6130 0 17875 0 23933 0
+The amount of time, measured in units of
+USER_HZ (1/100ths of a second on most architectures, use
+.I sysconf(_SC_CLK_TCK)
+to obtain the right value),
+.\" 1024 on Alpha and ia64
+that the system ("cpu" line) or the specific CPU ("cpu\fIN\fR" line)
+spent in various states:
+.RS
+.TP
+.I user
+(1) Time spent in user mode.
+.TP
+.I nice
+(2) Time spent in user mode with low priority (nice).
+.TP
+.I system
+(3) Time spent in system mode.
+.TP
+.I idle
+(4) Time spent in the idle task.
+.\" FIXME . Actually, the following info about the /proc/stat 'cpu' field
+.\"       does not seem to be quite right (at least in Linux 2.6.12 or Linux 3.6):
+.\"       the idle time in /proc/uptime does not quite match this value
+This value should be USER_HZ times the
+second entry in the
+.I /proc/uptime
+pseudo-file.
+.TP
+.IR iowait " (since Linux 2.5.41)"
+(5) Time waiting for I/O to complete.
+This value is not reliable, for the following reasons:
+.\" See kernel commit 9c240d757658a3ae9968dd309e674c61f07c7f48
+.RS
+.IP \[bu] 3
+The CPU will not wait for I/O to complete;
+iowait is the time that a task is waiting for I/O to complete.
+When a CPU goes into idle state for outstanding task I/O,
+another task will be scheduled on this CPU.
+.IP \[bu]
+On a multi-core CPU,
+the task waiting for I/O to complete is not running on any CPU,
+so the iowait of each CPU is difficult to calculate.
+.IP \[bu]
+The value in this field may
+.I decrease
+in certain conditions.
+.RE
+.TP
+.IR irq " (since Linux 2.6.0)"
+.\" Precisely: Linux 2.6.0-test4
+(6) Time servicing interrupts.
+.TP
+.IR softirq " (since Linux 2.6.0)"
+.\" Precisely: Linux 2.6.0-test4
+(7) Time servicing softirqs.
+.TP
+.IR steal " (since Linux 2.6.11)"
+(8) Stolen time, which is the time spent in other operating systems when
+running in a virtualized environment
+.TP
+.IR guest " (since Linux 2.6.24)"
+(9) Time spent running a virtual CPU for guest
+operating systems under the control of the Linux kernel.
+.\" See Changelog entry for 5e84cfde51cf303d368fcb48f22059f37b3872de
+.TP
+.IR guest_nice " (since Linux 2.6.33)"
+.\" commit ce0e7b28fb75cb003cfc8d0238613aaf1c55e797
+(10) Time spent running a niced guest (virtual CPU for guest
+operating systems under the control of the Linux kernel).
+.RE
+.TP
+\fIpage 5741 1808\fP
+The number of pages the system paged in and the number that were paged
+out (from disk).
+.TP
+\fIswap 1 0\fP
+The number of swap pages that have been brought in and out.
+.TP
+.\" FIXME . The following is not the full picture for the 'intr' of
+.\"       /proc/stat on 2.6:
+\fIintr 1462898\fP
+This line shows counts of interrupts serviced since boot time,
+for each of the possible system interrupts.
+The first column is the total of all interrupts serviced
+including unnumbered architecture specific interrupts;
+each subsequent column is the total for that particular numbered interrupt.
+Unnumbered interrupts are not shown, only summed into the total.
+.TP
+\fIdisk_io: (2,0):(31,30,5764,1,2) (3,0):\fP...
+(major,disk_idx):(noinfo, read_io_ops, blks_read, write_io_ops, blks_written)
+.br
+(Linux 2.4 only)
+.TP
+\fIctxt 115315\fP
+The number of context switches that the system underwent.
+.TP
+\fIbtime 769041601\fP
+boot time, in seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.TP
+\fIprocesses 86031\fP
+Number of forks since boot.
+.TP
+\fIprocs_running 6\fP
+Number of processes in runnable state.
+(Linux 2.5.45 onward.)
+.TP
+\fIprocs_blocked 2\fP
+Number of processes blocked waiting for I/O to complete.
+(Linux 2.5.45 onward.)
+.TP
+.I softirq 229245889 94 60001584 13619 5175704 2471304 28 51212741 59130143 0 51240672
+.\" commit d3d64df21d3d0de675a0d3ffa7c10514f3644b30
+This line shows the number of softirq for all CPUs.
+The first column is the total of all softirqs and
+each subsequent column is the total for particular softirq.
+(Linux 2.6.31 onward.)
+.RE
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_swaps.5 b/man/man5/proc_swaps.5
new file mode 100644
index 000000000..9b01f801d
--- /dev/null
+++ b/man/man5/proc_swaps.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_swaps 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/swaps \- swap areas
+.SH DESCRIPTION
+.TP
+.I /proc/swaps
+Swap areas in use.
+See also
+.BR swapon (8).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_sys.5 b/man/man5/proc_sys.5
new file mode 100644
index 000000000..4a2965842
--- /dev/null
+++ b/man/man5/proc_sys.5
@@ -0,0 +1,31 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/ \- system information, and sysctl pseudo-filesystem
+.SH DESCRIPTION
+.TP
+.I /proc/sys/
+This directory (present since Linux 1.3.57) contains a number of files
+and subdirectories corresponding to kernel variables.
+These variables can be read and in some cases modified using
+the \fI/proc\fP filesystem, and the (deprecated)
+.BR sysctl (2)
+system call.
+.IP
+String values may be terminated by either \[aq]\e0\[aq] or \[aq]\en\[aq].
+.IP
+Integer and long values may be written either in decimal or in
+hexadecimal notation (e.g., 0x3FFF).
+When writing multiple integer or long values, these may be separated
+by any of the following whitespace characters:
+\[aq]\ \[aq], \[aq]\et\[aq], or \[aq]\en\[aq].
+Using other separators leads to the error
+.BR EINVAL .
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_sys_abi.5 b/man/man5/proc_sys_abi.5
new file mode 100644
index 000000000..748ce50f3
--- /dev/null
+++ b/man/man5/proc_sys_abi.5
@@ -0,0 +1,24 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_abi 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/abi/ \- application binary information
+.SH DESCRIPTION
+.TP
+.IR /proc/sys/abi/ " (since Linux 2.4.10)"
+This directory may contain files with application binary information.
+.\" On some systems, it is not present.
+See the Linux kernel source file
+.I Documentation/sysctl/abi.rst
+(or
+.I Documentation/sysctl/abi.txt
+before Linux 5.3)
+for more information.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_debug.5 b/man/man5/proc_sys_debug.5
new file mode 100644
index 000000000..cf5632d70
--- /dev/null
+++ b/man/man5/proc_sys_debug.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_debug 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/debug/ \- debug
+.SH DESCRIPTION
+.TP
+.I /proc/sys/debug/
+This directory may be empty.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_dev.5 b/man/man5/proc_sys_dev.5
new file mode 100644
index 000000000..c1de19307
--- /dev/null
+++ b/man/man5/proc_sys_dev.5
@@ -0,0 +1,20 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_dev 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/dev/ \- device-specific information
+.SH DESCRIPTION
+.TP
+.I /proc/sys/dev/
+This directory contains device-specific information (e.g.,
+.IR dev/cdrom/info ).
+On
+some systems, it may be empty.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_fs.5 b/man/man5/proc_sys_fs.5
new file mode 100644
index 000000000..e745a64fd
--- /dev/null
+++ b/man/man5/proc_sys_fs.5
@@ -0,0 +1,471 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_fs 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/fs/ \- kernel variables related to filesystems
+.SH DESCRIPTION
+.TP
+.I /proc/sys/fs/
+This directory contains the files and subdirectories for kernel variables
+related to filesystems.
+.TP
+.IR /proc/sys/fs/aio\-max\-nr " and " /proc/sys/fs/aio\-nr " (since Linux 2.6.4)"
+.I aio\-nr
+is the running total of the number of events specified by
+.BR io_setup (2)
+calls for all currently active AIO contexts.
+If
+.I aio\-nr
+reaches
+.IR aio\-max\-nr ,
+then
+.BR io_setup (2)
+will fail with the error
+.BR EAGAIN .
+Raising
+.I aio\-max\-nr
+does not result in the preallocation or resizing
+of any kernel data structures.
+.TP
+.I /proc/sys/fs/binfmt_misc
+Documentation for files in this directory can be found
+in the Linux kernel source in the file
+.I Documentation/admin\-guide/binfmt\-misc.rst
+(or in
+.I Documentation/binfmt_misc.txt
+on older kernels).
+.TP
+.IR /proc/sys/fs/dentry\-state " (since Linux 2.2)"
+This file contains information about the status of the
+directory cache (dcache).
+The file contains six numbers,
+.IR nr_dentry ,
+.IR nr_unused ,
+.I age_limit
+(age in seconds),
+.I want_pages
+(pages requested by system) and two dummy values.
+.RS
+.IP \[bu] 3
+.I nr_dentry
+is the number of allocated dentries (dcache entries).
+This field is unused in Linux 2.2.
+.IP \[bu]
+.I nr_unused
+is the number of unused dentries.
+.IP \[bu]
+.I age_limit
+.\" looks like this is unused in Linux 2.2 to Linux 2.6
+is the age in seconds after which dcache entries
+can be reclaimed when memory is short.
+.IP \[bu]
+.I want_pages
+.\" looks like this is unused in Linux 2.2 to Linux 2.6
+is nonzero when the kernel has called shrink_dcache_pages() and the
+dcache isn't pruned yet.
+.RE
+.TP
+.I /proc/sys/fs/dir\-notify\-enable
+This file can be used to disable or enable the
+.I dnotify
+interface described in
+.BR fcntl (2)
+on a system-wide basis.
+A value of 0 in this file disables the interface,
+and a value of 1 enables it.
+.TP
+.I /proc/sys/fs/dquot\-max
+This file shows the maximum number of cached disk quota entries.
+On some (2.4) systems, it is not present.
+If the number of free cached disk quota entries is very low and
+you have some awesome number of simultaneous system users,
+you might want to raise the limit.
+.TP
+.I /proc/sys/fs/dquot\-nr
+This file shows the number of allocated disk quota
+entries and the number of free disk quota entries.
+.TP
+.IR /proc/sys/fs/epoll/ " (since Linux 2.6.28)"
+This directory contains the file
+.IR max_user_watches ,
+which can be used to limit the amount of kernel memory consumed by the
+.I epoll
+interface.
+For further details, see
+.BR epoll (7).
+.TP
+.I /proc/sys/fs/file\-max
+This file defines
+a system-wide limit on the number of open files for all processes.
+System calls that fail when encountering this limit fail with the error
+.BR ENFILE .
+(See also
+.BR setrlimit (2),
+which can be used by a process to set the per-process limit,
+.BR RLIMIT_NOFILE ,
+on the number of files it may open.)
+If you get lots
+of error messages in the kernel log about running out of file handles
+(open file descriptions)
+(look for "VFS: file\-max limit <number> reached"),
+try increasing this value:
+.IP
+.in +4n
+.EX
+echo 100000 > /proc/sys/fs/file\-max
+.EE
+.in
+.IP
+Privileged processes
+.RB ( CAP_SYS_ADMIN )
+can override the
+.I file\-max
+limit.
+.TP
+.I /proc/sys/fs/file\-nr
+This (read-only) file contains three numbers:
+the number of allocated file handles
+(i.e., the number of open file descriptions; see
+.BR open (2));
+the number of free file handles;
+and the maximum number of file handles (i.e., the same value as
+.IR /proc/sys/fs/file\-max ).
+If the number of allocated file handles is close to the
+maximum, you should consider increasing the maximum.
+Before Linux 2.6,
+the kernel allocated file handles dynamically,
+but it didn't free them again.
+Instead the free file handles were kept in a list for reallocation;
+the "free file handles" value indicates the size of that list.
+A large number of free file handles indicates that there was
+a past peak in the usage of open file handles.
+Since Linux 2.6, the kernel does deallocate freed file handles,
+and the "free file handles" value is always zero.
+.TP
+.IR /proc/sys/fs/inode\-max " (only present until Linux 2.2)"
+This file contains the maximum number of in-memory inodes.
+This value should be 3\[en]4 times larger
+than the value in
+.IR file\-max ,
+since \fIstdin\fP, \fIstdout\fP
+and network sockets also need an inode to handle them.
+When you regularly run out of inodes, you need to increase this value.
+.IP
+Starting with Linux 2.4,
+there is no longer a static limit on the number of inodes,
+and this file is removed.
+.TP
+.I /proc/sys/fs/inode\-nr
+This file contains the first two values from
+.IR inode\-state .
+.TP
+.I /proc/sys/fs/inode\-state
+This file
+contains seven numbers:
+.IR nr_inodes ,
+.IR nr_free_inodes ,
+.IR preshrink ,
+and four dummy values (always zero).
+.IP
+.I nr_inodes
+is the number of inodes the system has allocated.
+.\" This can be slightly more than
+.\" .I inode\-max
+.\" because Linux allocates them one page full at a time.
+.I nr_free_inodes
+represents the number of free inodes.
+.IP
+.I preshrink
+is nonzero when the
+.I nr_inodes
+>
+.I inode\-max
+and the system needs to prune the inode list instead of allocating more;
+since Linux 2.4, this field is a dummy value (always zero).
+.TP
+.IR /proc/sys/fs/inotify/ " (since Linux 2.6.13)"
+This directory contains files
+.IR max_queued_events ", " max_user_instances ", and " max_user_watches ,
+that can be used to limit the amount of kernel memory consumed by the
+.I inotify
+interface.
+For further details, see
+.BR inotify (7).
+.TP
+.I /proc/sys/fs/lease\-break\-time
+This file specifies the grace period that the kernel grants to a process
+holding a file lease
+.RB ( fcntl (2))
+after it has sent a signal to that process notifying it
+that another process is waiting to open the file.
+If the lease holder does not remove or downgrade the lease within
+this grace period, the kernel forcibly breaks the lease.
+.TP
+.I /proc/sys/fs/leases\-enable
+This file can be used to enable or disable file leases
+.RB ( fcntl (2))
+on a system-wide basis.
+If this file contains the value 0, leases are disabled.
+A nonzero value enables leases.
+.TP
+.IR /proc/sys/fs/mount\-max " (since Linux 4.9)"
+.\" commit d29216842a85c7970c536108e093963f02714498
+The value in this file specifies the maximum number of mounts that may exist
+in a mount namespace.
+The default value in this file is 100,000.
+.TP
+.IR /proc/sys/fs/mqueue/ " (since Linux 2.6.6)"
+This directory contains files
+.IR msg_max ", " msgsize_max ", and " queues_max ,
+controlling the resources used by POSIX message queues.
+See
+.BR mq_overview (7)
+for details.
+.TP
+.IR /proc/sys/fs/nr_open " (since Linux 2.6.25)"
+.\" commit 9cfe015aa424b3c003baba3841a60dd9b5ad319b
+This file imposes a ceiling on the value to which the
+.B RLIMIT_NOFILE
+resource limit can be raised (see
+.BR getrlimit (2)).
+This ceiling is enforced for both unprivileged and privileged process.
+The default value in this file is 1048576.
+(Before Linux 2.6.25, the ceiling for
+.B RLIMIT_NOFILE
+was hard-coded to the same value.)
+.TP
+.IR /proc/sys/fs/overflowgid " and " /proc/sys/fs/overflowuid
+These files
+allow you to change the value of the fixed UID and GID.
+The default is 65534.
+Some filesystems support only 16-bit UIDs and GIDs, although in Linux
+UIDs and GIDs are 32 bits.
+When one of these filesystems is mounted
+with writes enabled, any UID or GID that would exceed 65535 is translated
+to the overflow value before being written to disk.
+.TP
+.IR /proc/sys/fs/pipe\-max\-size " (since Linux 2.6.35)"
+See
+.BR pipe (7).
+.TP
+.IR /proc/sys/fs/pipe\-user\-pages\-hard " (since Linux 4.5)"
+See
+.BR pipe (7).
+.TP
+.IR /proc/sys/fs/pipe\-user\-pages\-soft " (since Linux 4.5)"
+See
+.BR pipe (7).
+.TP
+.IR /proc/sys/fs/protected_fifos " (since Linux 4.19)"
+The value in this file is/can be set to one of the following:
+.RS
+.TP 4
+0
+Writing to FIFOs is unrestricted.
+.TP
+1
+Don't allow
+.B O_CREAT
+.BR open (2)
+on FIFOs that the caller doesn't own in world-writable sticky directories,
+unless the FIFO is owned by the owner of the directory.
+.TP
+2
+As for the value 1,
+but the restriction also applies to group-writable sticky directories.
+.RE
+.IP
+The intent of the above protections is to avoid unintentional writes to an
+attacker-controlled FIFO when a program expected to create a regular file.
+.TP
+.IR /proc/sys/fs/protected_hardlinks " (since Linux 3.6)"
+.\" commit 800179c9b8a1e796e441674776d11cd4c05d61d7
+When the value in this file is 0,
+no restrictions are placed on the creation of hard links
+(i.e., this is the historical behavior before Linux 3.6).
+When the value in this file is 1,
+a hard link can be created to a target file
+only if one of the following conditions is true:
+.RS
+.IP \[bu] 3
+The calling process has the
+.B CAP_FOWNER
+capability in its user namespace
+and the file UID has a mapping in the namespace.
+.IP \[bu]
+The filesystem UID of the process creating the link matches
+the owner (UID) of the target file
+(as described in
+.BR credentials (7),
+a process's filesystem UID is normally the same as its effective UID).
+.IP \[bu]
+All of the following conditions are true:
+.RS 4
+.IP \[bu] 3
+the target is a regular file;
+.IP \[bu]
+the target file does not have its set-user-ID mode bit enabled;
+.IP \[bu]
+the target file does not have both its set-group-ID and
+group-executable mode bits enabled; and
+.IP \[bu]
+the caller has permission to read and write the target file
+(either via the file's permissions mask or because it has
+suitable capabilities).
+.RE
+.RE
+.IP
+The default value in this file is 0.
+Setting the value to 1
+prevents a longstanding class of security issues caused by
+hard-link-based time-of-check, time-of-use races,
+most commonly seen in world-writable directories such as
+.IR /tmp .
+The common method of exploiting this flaw
+is to cross privilege boundaries when following a given hard link
+(i.e., a root process follows a hard link created by another user).
+Additionally, on systems without separated partitions,
+this stops unauthorized users from "pinning" vulnerable set-user-ID and
+set-group-ID files against being upgraded by
+the administrator, or linking to special files.
+.TP
+.IR /proc/sys/fs/protected_regular " (since Linux 4.19)"
+The value in this file is/can be set to one of the following:
+.RS
+.TP 4
+0
+Writing to regular files is unrestricted.
+.TP
+1
+Don't allow
+.B O_CREAT
+.BR open (2)
+on regular files that the caller doesn't own in
+world-writable sticky directories,
+unless the regular file is owned by the owner of the directory.
+.TP
+2
+As for the value 1,
+but the restriction also applies to group-writable sticky directories.
+.RE
+.IP
+The intent of the above protections is similar to
+.IR protected_fifos ,
+but allows an application to
+avoid writes to an attacker-controlled regular file,
+where the application expected to create one.
+.TP
+.IR /proc/sys/fs/protected_symlinks " (since Linux 3.6)"
+.\" commit 800179c9b8a1e796e441674776d11cd4c05d61d7
+When the value in this file is 0,
+no restrictions are placed on following symbolic links
+(i.e., this is the historical behavior before Linux 3.6).
+When the value in this file is 1, symbolic links are followed only
+in the following circumstances:
+.RS
+.IP \[bu] 3
+the filesystem UID of the process following the link matches
+the owner (UID) of the symbolic link
+(as described in
+.BR credentials (7),
+a process's filesystem UID is normally the same as its effective UID);
+.IP \[bu]
+the link is not in a sticky world-writable directory; or
+.IP \[bu]
+the symbolic link and its parent directory have the same owner (UID)
+.RE
+.IP
+A system call that fails to follow a symbolic link
+because of the above restrictions returns the error
+.B EACCES
+in
+.IR errno .
+.IP
+The default value in this file is 0.
+Setting the value to 1 avoids a longstanding class of security issues
+based on time-of-check, time-of-use races when accessing symbolic links.
+.TP
+.IR /proc/sys/fs/suid_dumpable " (since Linux 2.6.13)"
+.\" The following is based on text from Documentation/sysctl/kernel.txt
+The value in this file is assigned to a process's "dumpable" flag
+in the circumstances described in
+.BR prctl (2).
+In effect,
+the value in this file determines whether core dump files are
+produced for set-user-ID or otherwise protected/tainted binaries.
+The "dumpable" setting also affects the ownership of files in a process's
+.IR /proc/ pid
+directory, as described above.
+.IP
+Three different integer values can be specified:
+.RS
+.TP
+\fI0\ (default)\fP
+.\" In kernel source: SUID_DUMP_DISABLE
+This provides the traditional (pre-Linux 2.6.13) behavior.
+A core dump will not be produced for a process which has
+changed credentials (by calling
+.BR seteuid (2),
+.BR setgid (2),
+or similar, or by executing a set-user-ID or set-group-ID program)
+or whose binary does not have read permission enabled.
+.TP
+\fI1\ ("debug")\fP
+.\" In kernel source: SUID_DUMP_USER
+All processes dump core when possible.
+(Reasons why a process might nevertheless not dump core are described in
+.BR core (5).)
+The core dump is owned by the filesystem user ID of the dumping process
+and no security is applied.
+This is intended for system debugging situations only:
+this mode is insecure because it allows unprivileged users to
+examine the memory contents of privileged processes.
+.TP
+\fI2\ ("suidsafe")\fP
+.\" In kernel source: SUID_DUMP_ROOT
+Any binary which normally would not be dumped (see "0" above)
+is dumped readable by root only.
+This allows the user to remove the core dump file but not to read it.
+For security reasons core dumps in this mode will not overwrite one
+another or other files.
+This mode is appropriate when administrators are
+attempting to debug problems in a normal environment.
+.IP
+Additionally, since Linux 3.6,
+.\" 9520628e8ceb69fa9a4aee6b57f22675d9e1b709
+.I /proc/sys/kernel/core_pattern
+must either be an absolute pathname
+or a pipe command, as detailed in
+.BR core (5).
+Warnings will be written to the kernel log if
+.I core_pattern
+does not follow these rules, and no core dump will be produced.
+.\" 54b501992dd2a839e94e76aa392c392b55080ce8
+.RE
+.IP
+For details of the effect of a process's "dumpable" setting
+on ptrace access mode checking, see
+.BR ptrace (2).
+.TP
+.I /proc/sys/fs/super\-max
+This file
+controls the maximum number of superblocks, and
+thus the maximum number of mounted filesystems the kernel
+can have.
+You need increase only
+.I super\-max
+if you need to mount more filesystems than the current value in
+.I super\-max
+allows you to.
+.TP
+.I /proc/sys/fs/super\-nr
+This file
+contains the number of filesystems currently mounted.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_kernel.5 b/man/man5/proc_sys_kernel.5
new file mode 100644
index 000000000..3cf664cb4
--- /dev/null
+++ b/man/man5/proc_sys_kernel.5
@@ -0,0 +1,691 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_kernel 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/kernel/ \- control a range of kernel parameters
+.SH DESCRIPTION
+.TP
+.I /proc/sys/kernel/
+This directory contains files controlling a range of kernel parameters,
+as described below.
+.TP
+.I /proc/sys/kernel/acct
+This file
+contains three numbers:
+.IR highwater ,
+.IR lowwater ,
+and
+.IR frequency .
+If BSD-style process accounting is enabled, these values control
+its behavior.
+If free space on filesystem where the log lives goes below
+.I lowwater
+percent, accounting suspends.
+If free space gets above
+.I highwater
+percent, accounting resumes.
+.I frequency
+determines
+how often the kernel checks the amount of free space (value is in
+seconds).
+Default values are 4, 2, and 30.
+That is, suspend accounting if 2% or less space is free; resume it
+if 4% or more space is free; consider information about amount of free space
+valid for 30 seconds.
+.TP
+.IR /proc/sys/kernel/auto_msgmni " (Linux 2.6.27 to Linux 3.18)"
+.\" commit 9eefe520c814f6f62c5d36a2ddcd3fb99dfdb30e (introduces feature)
+.\" commit 0050ee059f7fc86b1df2527aaa14ed5dc72f9973 (rendered redundant)
+From Linux 2.6.27 to Linux 3.18,
+this file was used to control recomputing of the value in
+.I /proc/sys/kernel/msgmni
+upon the addition or removal of memory or upon IPC namespace creation/removal.
+Echoing "1" into this file enabled
+.I msgmni
+automatic recomputing (and triggered a recomputation of
+.I msgmni
+based on the current amount of available memory and number of IPC namespaces).
+Echoing "0" disabled automatic recomputing.
+(Automatic recomputing was also disabled if a value was explicitly assigned to
+.IR /proc/sys/kernel/msgmni .)
+The default value in
+.I auto_msgmni
+was 1.
+.IP
+Since Linux 3.19, the content of this file has no effect (because
+.I msgmni
+.\" FIXME Must document the 3.19 'msgmni' changes.
+defaults to near the maximum value possible),
+and reads from this file always return the value "0".
+.TP
+.IR /proc/sys/kernel/cap_last_cap " (since Linux 3.2)"
+See
+.BR capabilities (7).
+.TP
+.IR /proc/sys/kernel/cap\-bound " (from Linux 2.2 to Linux 2.6.24)"
+This file holds the value of the kernel
+.I "capability bounding set"
+(expressed as a signed decimal number).
+This set is ANDed against the capabilities permitted to a process
+during
+.BR execve (2).
+Starting with Linux 2.6.25,
+the system-wide capability bounding set disappeared,
+and was replaced by a per-thread bounding set; see
+.BR capabilities (7).
+.TP
+.I /proc/sys/kernel/core_pattern
+See
+.BR core (5).
+.TP
+.I /proc/sys/kernel/core_pipe_limit
+See
+.BR core (5).
+.TP
+.I /proc/sys/kernel/core_uses_pid
+See
+.BR core (5).
+.TP
+.I /proc/sys/kernel/ctrl\-alt\-del
+This file
+controls the handling of Ctrl-Alt-Del from the keyboard.
+When the value in this file is 0, Ctrl-Alt-Del is trapped and
+sent to the
+.BR init (1)
+program to handle a graceful restart.
+When the value is greater than zero, Linux's reaction to a Vulcan
+Nerve Pinch (tm) will be an immediate reboot, without even
+syncing its dirty buffers.
+Note: when a program (like dosemu) has the keyboard in "raw"
+mode, the Ctrl-Alt-Del is intercepted by the program before it
+ever reaches the kernel tty layer, and it's up to the program
+to decide what to do with it.
+.TP
+.IR /proc/sys/kernel/dmesg_restrict " (since Linux 2.6.37)"
+The value in this file determines who can see kernel syslog contents.
+A value of 0 in this file imposes no restrictions.
+If the value is 1, only privileged users can read the kernel syslog.
+(See
+.BR syslog (2)
+for more details.)
+Since Linux 3.4,
+.\" commit 620f6e8e855d6d447688a5f67a4e176944a084e8
+only users with the
+.B CAP_SYS_ADMIN
+capability may change the value in this file.
+.TP
+.IR /proc/sys/kernel/domainname " and " /proc/sys/kernel/hostname
+can be used to set the NIS/YP domainname and the
+hostname of your box in exactly the same way as the commands
+.BR domainname (1)
+and
+.BR hostname (1),
+that is:
+.IP
+.in +4n
+.EX
+.RB "#" " echo \[aq]darkstar\[aq] > /proc/sys/kernel/hostname"
+.RB "#" " echo \[aq]mydomain\[aq] > /proc/sys/kernel/domainname"
+.EE
+.in
+.IP
+has the same effect as
+.IP
+.in +4n
+.EX
+.RB "#" " hostname \[aq]darkstar\[aq]"
+.RB "#" " domainname \[aq]mydomain\[aq]"
+.EE
+.in
+.IP
+Note, however, that the classic darkstar.frop.org has the
+hostname "darkstar" and DNS (Internet Domain Name Server)
+domainname "frop.org", not to be confused with the NIS (Network
+Information Service) or YP (Yellow Pages) domainname.
+These two
+domain names are in general different.
+For a detailed discussion
+see the
+.BR hostname (1)
+man page.
+.TP
+.I /proc/sys/kernel/hotplug
+This file
+contains the pathname for the hotplug policy agent.
+The default value in this file is
+.IR /sbin/hotplug .
+.TP
+.\" Removed in commit 87f504e5c78b910b0c1d6ffb89bc95e492322c84 (tglx/history.git)
+.IR /proc/sys/kernel/htab\-reclaim " (before Linux 2.4.9.2)"
+(PowerPC only) If this file is set to a nonzero value,
+the PowerPC htab
+.\" removed in commit 1b483a6a7b2998e9c98ad985d7494b9b725bd228, before Linux 2.6.28
+(see kernel file
+.IR Documentation/powerpc/ppc_htab.txt )
+is pruned
+each time the system hits the idle loop.
+.TP
+.I /proc/sys/kernel/keys/
+This directory contains various files that define parameters and limits
+for the key-management facility.
+These files are described in
+.BR keyrings (7).
+.TP
+.IR /proc/sys/kernel/kptr_restrict " (since Linux 2.6.38)"
+.\" 455cd5ab305c90ffc422dd2e0fb634730942b257
+The value in this file determines whether kernel addresses are exposed via
+.I /proc
+files and other interfaces.
+A value of 0 in this file imposes no restrictions.
+If the value is 1, kernel pointers printed using the
+.I %pK
+format specifier will be replaced with zeros unless the user has the
+.B CAP_SYSLOG
+capability.
+If the value is 2, kernel pointers printed using the
+.I %pK
+format specifier will be replaced with zeros regardless
+of the user's capabilities.
+The initial default value for this file was 1,
+but the default was changed
+.\" commit 411f05f123cbd7f8aa1edcae86970755a6e2a9d9
+to 0 in Linux 2.6.39.
+Since Linux 3.4,
+.\" commit 620f6e8e855d6d447688a5f67a4e176944a084e8
+only users with the
+.B CAP_SYS_ADMIN
+capability can change the value in this file.
+.TP
+.I /proc/sys/kernel/l2cr
+(PowerPC only) This file
+contains a flag that controls the L2 cache of G3 processor
+boards.
+If 0, the cache is disabled.
+Enabled if nonzero.
+.TP
+.I /proc/sys/kernel/modprobe
+This file contains the pathname for the kernel module loader.
+The default value is
+.IR /sbin/modprobe .
+The file is present only if the kernel is built with the
+.B CONFIG_MODULES
+.RB ( CONFIG_KMOD
+in Linux 2.6.26 and earlier)
+option enabled.
+It is described by the Linux kernel source file
+.I Documentation/kmod.txt
+(present only in Linux 2.4 and earlier).
+.TP
+.IR /proc/sys/kernel/modules_disabled " (since Linux 2.6.31)"
+.\" 3d43321b7015387cfebbe26436d0e9d299162ea1
+.\" From Documentation/sysctl/kernel.txt
+A toggle value indicating if modules are allowed to be loaded
+in an otherwise modular kernel.
+This toggle defaults to off (0), but can be set true (1).
+Once true, modules can be neither loaded nor unloaded,
+and the toggle cannot be set back to false.
+The file is present only if the kernel is built with the
+.B CONFIG_MODULES
+option enabled.
+.TP
+.IR /proc/sys/kernel/msgmax " (since Linux 2.2)"
+This file defines
+a system-wide limit specifying the maximum number of bytes in
+a single message written on a System V message queue.
+.TP
+.IR /proc/sys/kernel/msgmni " (since Linux 2.4)"
+This file defines the system-wide limit on the number of
+message queue identifiers.
+See also
+.IR /proc/sys/kernel/auto_msgmni .
+.TP
+.IR /proc/sys/kernel/msgmnb " (since Linux 2.2)"
+This file defines a system-wide parameter used to initialize the
+.I msg_qbytes
+setting for subsequently created message queues.
+The
+.I msg_qbytes
+setting specifies the maximum number of bytes that may be written to the
+message queue.
+.TP
+.IR /proc/sys/kernel/ngroups_max " (since Linux 2.6.4)"
+This is a read-only file that displays the upper limit on the
+number of a process's group memberships.
+.TP
+.IR /proc/sys/kernel/ns_last_pid " (since Linux 3.3)"
+See
+.BR pid_namespaces (7).
+.TP
+.IR /proc/sys/kernel/ostype " and " /proc/sys/kernel/osrelease
+These files
+give substrings of
+.IR /proc/version .
+.TP
+.IR /proc/sys/kernel/overflowgid " and " /proc/sys/kernel/overflowuid
+These files duplicate the files
+.I /proc/sys/fs/overflowgid
+and
+.IR /proc/sys/fs/overflowuid .
+.TP
+.I /proc/sys/kernel/panic
+This file gives read/write access to the kernel variable
+.IR panic_timeout .
+If this is zero, the kernel will loop on a panic; if nonzero,
+it indicates that the kernel should autoreboot after this number
+of seconds.
+When you use the
+software watchdog device driver, the recommended setting is 60.
+.TP
+.IR /proc/sys/kernel/panic_on_oops " (since Linux 2.5.68)"
+This file controls the kernel's behavior when an oops
+or BUG is encountered.
+If this file contains 0, then the system
+tries to continue operation.
+If it contains 1, then the system
+delays a few seconds (to give klogd time to record the oops output)
+and then panics.
+If the
+.I /proc/sys/kernel/panic
+file is also nonzero, then the machine will be rebooted.
+.TP
+.IR /proc/sys/kernel/pid_max " (since Linux 2.5.34)"
+This file specifies the value at which PIDs wrap around
+(i.e., the value in this file is one greater than the maximum PID).
+PIDs greater than this value are not allocated;
+thus, the value in this file also acts as a system-wide limit
+on the total number of processes and threads.
+The default value for this file, 32768,
+results in the same range of PIDs as on earlier kernels.
+On 32-bit platforms, 32768 is the maximum value for
+.IR pid_max .
+On 64-bit systems,
+.I pid_max
+can be set to any value up to 2\[ha]22
+.RB ( PID_MAX_LIMIT ,
+approximately 4 million).
+.\" Prior to Linux 2.6.10, pid_max could also be raised above 32768 on 32-bit
+.\" platforms, but this broke /proc/[pid]
+.\" See http://marc.theaimsgroup.com/?l=linux-kernel&m=109513010926152&w=2
+.TP
+.IR /proc/sys/kernel/powersave\-nap " (PowerPC only)"
+This file contains a flag.
+If set, Linux-PPC will use the "nap" mode of
+powersaving,
+otherwise the "doze" mode will be used.
+.TP
+.I /proc/sys/kernel/printk
+See
+.BR syslog (2).
+.TP
+.IR /proc/sys/kernel/pty " (since Linux 2.6.4)"
+This directory contains two files relating to the number of UNIX 98
+pseudoterminals (see
+.BR pts (4))
+on the system.
+.TP
+.I /proc/sys/kernel/pty/max
+This file defines the maximum number of pseudoterminals.
+.\" FIXME Document /proc/sys/kernel/pty/reserve
+.\"     New in Linux 3.3
+.\"     commit e9aba5158a80098447ff207a452a3418ae7ee386
+.TP
+.I /proc/sys/kernel/pty/nr
+This read-only file
+indicates how many pseudoterminals are currently in use.
+.TP
+.I /proc/sys/kernel/random/
+This directory
+contains various parameters controlling the operation of the file
+.IR /dev/random .
+See
+.BR random (4)
+for further information.
+.TP
+.IR /proc/sys/kernel/random/uuid " (since Linux 2.4)"
+Each read from this read-only file returns a randomly generated 128-bit UUID,
+as a string in the standard UUID format.
+.TP
+.IR /proc/sys/kernel/randomize_va_space " (since Linux 2.6.12)"
+.\" Some further details can be found in Documentation/sysctl/kernel.txt
+Select the address space layout randomization (ASLR) policy for the system
+(on architectures that support ASLR).
+Three values are supported for this file:
+.RS
+.TP
+.B 0
+Turn ASLR off.
+This is the default for architectures that don't support ASLR,
+and when the kernel is booted with the
+.I norandmaps
+parameter.
+.TP
+.B 1
+Make the addresses of
+.BR mmap (2)
+allocations, the stack, and the VDSO page randomized.
+Among other things, this means that shared libraries will be
+loaded at randomized addresses.
+The text segment of PIE-linked binaries will also be loaded
+at a randomized address.
+This value is the default if the kernel was configured with
+.BR CONFIG_COMPAT_BRK .
+.TP
+.B 2
+(Since Linux 2.6.25)
+.\" commit c1d171a002942ea2d93b4fbd0c9583c56fce0772
+Also support heap randomization.
+This value is the default if the kernel was not configured with
+.BR CONFIG_COMPAT_BRK .
+.RE
+.TP
+.I /proc/sys/kernel/real\-root\-dev
+This file is documented in the Linux kernel source file
+.I Documentation/admin\-guide/initrd.rst
+.\" commit 9d85025b0418163fae079c9ba8f8445212de8568
+(or
+.I Documentation/initrd.txt
+before Linux 4.10).
+.TP
+.IR /proc/sys/kernel/reboot\-cmd " (Sparc only)"
+This file seems to be a way to give an argument to the SPARC
+ROM/Flash boot loader.
+Maybe to tell it what to do after
+rebooting?
+.TP
+.I /proc/sys/kernel/rtsig\-max
+(Up to and including Linux 2.6.7; see
+.BR setrlimit (2))
+This file can be used to tune the maximum number
+of POSIX real-time (queued) signals that can be outstanding
+in the system.
+.TP
+.I /proc/sys/kernel/rtsig\-nr
+(Up to and including Linux 2.6.7.)
+This file shows the number of POSIX real-time signals currently queued.
+.TP
+.IR /proc/ pid /sched_autogroup_enabled " (since Linux 2.6.38)"
+.\" commit 5091faa449ee0b7d73bc296a93bca9540fc51d0a
+See
+.BR sched (7).
+.TP
+.IR /proc/sys/kernel/sched_child_runs_first " (since Linux 2.6.23)"
+If this file contains the value zero, then, after a
+.BR fork (2),
+the parent is first scheduled on the CPU.
+If the file contains a nonzero value,
+then the child is scheduled first on the CPU.
+(Of course, on a multiprocessor system,
+the parent and the child might both immediately be scheduled on a CPU.)
+.TP
+.IR /proc/sys/kernel/sched_rr_timeslice_ms " (since Linux 3.9)"
+See
+.BR sched_rr_get_interval (2).
+.TP
+.IR /proc/sys/kernel/sched_rt_period_us " (since Linux 2.6.25)"
+See
+.BR sched (7).
+.TP
+.IR /proc/sys/kernel/sched_rt_runtime_us " (since Linux 2.6.25)"
+See
+.BR sched (7).
+.TP
+.IR /proc/sys/kernel/seccomp/ " (since Linux 4.14)"
+.\" commit 8e5f1ad116df6b0de65eac458d5e7c318d1c05af
+This directory provides additional seccomp information and
+configuration.
+See
+.BR seccomp (2)
+for further details.
+.TP
+.IR /proc/sys/kernel/sem " (since Linux 2.4)"
+This file contains 4 numbers defining limits for System V IPC semaphores.
+These fields are, in order:
+.RS
+.TP
+SEMMSL
+The maximum semaphores per semaphore set.
+.TP
+SEMMNS
+A system-wide limit on the number of semaphores in all semaphore sets.
+.TP
+SEMOPM
+The maximum number of operations that may be specified in a
+.BR semop (2)
+call.
+.TP
+SEMMNI
+A system-wide limit on the maximum number of semaphore identifiers.
+.RE
+.TP
+.I /proc/sys/kernel/sg\-big\-buff
+This file
+shows the size of the generic SCSI device (sg) buffer.
+You can't tune it just yet, but you could change it at
+compile time by editing
+.I include/scsi/sg.h
+and changing
+the value of
+.BR SG_BIG_BUFF .
+However, there shouldn't be any reason to change this value.
+.TP
+.IR /proc/sys/kernel/shm_rmid_forced " (since Linux 3.1)"
+.\" commit b34a6b1da371ed8af1221459a18c67970f7e3d53
+.\" See also Documentation/sysctl/kernel.txt
+If this file is set to 1, all System V shared memory segments will
+be marked for destruction as soon as the number of attached processes
+falls to zero;
+in other words, it is no longer possible to create shared memory segments
+that exist independently of any attached process.
+.IP
+The effect is as though a
+.BR shmctl (2)
+.B IPC_RMID
+is performed on all existing segments as well as all segments
+created in the future (until this file is reset to 0).
+Note that existing segments that are attached to no process will be
+immediately destroyed when this file is set to 1.
+Setting this option will also destroy segments that were created,
+but never attached,
+upon termination of the process that created the segment with
+.BR shmget (2).
+.IP
+Setting this file to 1 provides a way of ensuring that
+all System V shared memory segments are counted against the
+resource usage and resource limits (see the description of
+.B RLIMIT_AS
+in
+.BR getrlimit (2))
+of at least one process.
+.IP
+Because setting this file to 1 produces behavior that is nonstandard
+and could also break existing applications,
+the default value in this file is 0.
+Set this file to 1 only if you have a good understanding
+of the semantics of the applications using
+System V shared memory on your system.
+.TP
+.IR /proc/sys/kernel/shmall " (since Linux 2.2)"
+This file
+contains the system-wide limit on the total number of pages of
+System V shared memory.
+.TP
+.IR /proc/sys/kernel/shmmax " (since Linux 2.2)"
+This file
+can be used to query and set the run-time limit
+on the maximum (System V IPC) shared memory segment size that can be
+created.
+Shared memory segments up to 1 GB are now supported in the
+kernel.
+This value defaults to
+.BR SHMMAX .
+.TP
+.IR /proc/sys/kernel/shmmni " (since Linux 2.4)"
+This file
+specifies the system-wide maximum number of System V shared memory
+segments that can be created.
+.TP
+.IR /proc/sys/kernel/sysctl_writes_strict " (since Linux 3.16)"
+.\" commit f88083005ab319abba5d0b2e4e997558245493c8
+.\" commit 2ca9bb456ada8bcbdc8f77f8fc78207653bbaa92
+.\" commit f4aacea2f5d1a5f7e3154e967d70cf3f711bcd61
+.\" commit 24fe831c17ab8149413874f2fd4e5c8a41fcd294
+The value in this file determines how the file offset affects
+the behavior of updating entries in files under
+.IR /proc/sys .
+The file has three possible values:
+.RS
+.TP 4
+\-1
+This provides legacy handling, with no printk warnings.
+Each
+.BR write (2)
+must fully contain the value to be written,
+and multiple writes on the same file descriptor
+will overwrite the entire value, regardless of the file position.
+.TP
+0
+(default) This provides the same behavior as for \-1,
+but printk warnings are written for processes that
+perform writes when the file offset is not 0.
+.TP
+1
+Respect the file offset when writing strings into
+.I /proc/sys
+files.
+Multiple writes will
+.I append
+to the value buffer.
+Anything written beyond the maximum length
+of the value buffer will be ignored.
+Writes to numeric
+.I /proc/sys
+entries must always be at file offset 0 and the value must be
+fully contained in the buffer provided to
+.BR write (2).
+.\" FIXME .
+.\"     With /proc/sys/kernel/sysctl_writes_strict==1, writes at an
+.\"     offset other than 0 do not generate an error. Instead, the
+.\"     write() succeeds, but the file is left unmodified.
+.\"     This is surprising. The behavior may change in the future.
+.\"     See thread.gmane.org/gmane.linux.man/9197
+.\"		From: Michael Kerrisk (man-pages <mtk.manpages@...>
+.\"		Subject: sysctl_writes_strict documentation + an oddity?
+.\"		Newsgroups: gmane.linux.man, gmane.linux.kernel
+.\"		Date: 2015-05-09 08:54:11 GMT
+.RE
+.TP
+.I /proc/sys/kernel/sysrq
+This file controls the functions allowed to be invoked by the SysRq key.
+By default,
+the file contains 1 meaning that every possible SysRq request is allowed
+(in older kernel versions, SysRq was disabled by default,
+and you were required to specifically enable it at run-time,
+but this is not the case any more).
+Possible values in this file are:
+.RS
+.TP 5
+0
+Disable sysrq completely
+.TP
+1
+Enable all functions of sysrq
+.TP
+> 1
+Bit mask of allowed sysrq functions, as follows:
+.PD 0
+.RS
+.TP 5
+\ \ 2
+Enable control of console logging level
+.TP
+\ \ 4
+Enable control of keyboard (SAK, unraw)
+.TP
+\ \ 8
+Enable debugging dumps of processes etc.
+.TP
+\ 16
+Enable sync command
+.TP
+\ 32
+Enable remount read-only
+.TP
+\ 64
+Enable signaling of processes (term, kill, oom-kill)
+.TP
+128
+Allow reboot/poweroff
+.TP
+256
+Allow nicing of all real-time tasks
+.RE
+.PD
+.RE
+.IP
+This file is present only if the
+.B CONFIG_MAGIC_SYSRQ
+kernel configuration option is enabled.
+For further details see the Linux kernel source file
+.I Documentation/admin\-guide/sysrq.rst
+.\" commit 9d85025b0418163fae079c9ba8f8445212de8568
+(or
+.I Documentation/sysrq.txt
+before Linux 4.10).
+.TP
+.I /proc/sys/kernel/version
+This file contains a string such as:
+.IP
+.in +4n
+.EX
+#5 Wed Feb 25 21:49:24 MET 1998
+.EE
+.in
+.IP
+The "#5" means that
+this is the fifth kernel built from this source base and the
+date following it indicates the time the kernel was built.
+.TP
+.IR /proc/sys/kernel/threads\-max " (since Linux 2.3.11)"
+.\" The following is based on Documentation/sysctl/kernel.txt
+This file specifies the system-wide limit on the number of
+threads (tasks) that can be created on the system.
+.IP
+Since Linux 4.1,
+.\" commit 230633d109e35b0a24277498e773edeb79b4a331
+the value that can be written to
+.I threads\-max
+is bounded.
+The minimum value that can be written is 20.
+The maximum value that can be written is given by the
+constant
+.B FUTEX_TID_MASK
+(0x3fffffff).
+If a value outside of this range is written to
+.IR threads\-max ,
+the error
+.B EINVAL
+occurs.
+.IP
+The value written is checked against the available RAM pages.
+If the thread structures would occupy too much (more than 1/8th)
+of the available RAM pages,
+.I threads\-max
+is reduced accordingly.
+.TP
+.IR /proc/sys/kernel/yama/ptrace_scope " (since Linux 3.5)"
+See
+.BR ptrace (2).
+.TP
+.IR /proc/sys/kernel/zero\-paged " (PowerPC only)"
+This file
+contains a flag.
+When enabled (nonzero), Linux-PPC will pre-zero pages in
+the idle loop, possibly speeding up get_free_pages.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_net.5 b/man/man5/proc_sys_net.5
new file mode 100644
index 000000000..bd29738ba
--- /dev/null
+++ b/man/man5/proc_sys_net.5
@@ -0,0 +1,34 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_net 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/net/ \- networking
+.SH DESCRIPTION
+.TP
+.I /proc/sys/net/
+This directory contains networking stuff.
+Explanations for some of the files under this directory can be found in
+.BR tcp (7)
+and
+.BR ip (7).
+.TP
+.I /proc/sys/net/core/bpf_jit_enable
+See
+.BR bpf (2).
+.TP
+.I /proc/sys/net/core/somaxconn
+This file defines a ceiling value for the
+.I backlog
+argument of
+.BR listen (2);
+see the
+.BR listen (2)
+manual page for details.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_net (5)
diff --git a/man/man5/proc_sys_proc.5 b/man/man5/proc_sys_proc.5
new file mode 100644
index 000000000..21eaf2750
--- /dev/null
+++ b/man/man5/proc_sys_proc.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_proc 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/proc/ \- ???
+.SH DESCRIPTION
+.TP
+.I /proc/sys/proc/
+This directory may be empty.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_sunrpc.5 b/man/man5/proc_sys_sunrpc.5
new file mode 100644
index 000000000..7b47e9317
--- /dev/null
+++ b/man/man5/proc_sys_sunrpc.5
@@ -0,0 +1,19 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_sunrpc 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/sunrpc/ \- Sun remote procedure call for NFS
+.SH DESCRIPTION
+.TP
+.I /proc/sys/sunrpc/
+This directory supports Sun remote procedure call for network filesystem
+(NFS).
+On some systems, it is not present.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_user.5 b/man/man5/proc_sys_user.5
new file mode 100644
index 000000000..1566e7630
--- /dev/null
+++ b/man/man5/proc_sys_user.5
@@ -0,0 +1,18 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_user 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/user/ \- limits on the number of namespaces of various types
+.SH DESCRIPTION
+.TP
+.IR /proc/sys/user/ " (since Linux 4.9)"
+See
+.BR namespaces (7).
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sys_vm.5 b/man/man5/proc_sys_vm.5
new file mode 100644
index 000000000..17a7dd2ec
--- /dev/null
+++ b/man/man5/proc_sys_vm.5
@@ -0,0 +1,420 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Andries Brouwer <aeb@cwi.nl>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sys_vm 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sys/vm/ \- virtual memory subsystem
+.SH DESCRIPTION
+.TP
+.I /proc/sys/vm/
+This directory contains files for memory management tuning, buffer, and
+cache management.
+.TP
+.IR /proc/sys/vm/admin_reserve_kbytes " (since Linux 3.10)"
+.\" commit 4eeab4f5580d11bffedc697684b91b0bca0d5009
+This file defines the amount of free memory (in KiB) on the system that
+should be reserved for users with the capability
+.BR CAP_SYS_ADMIN .
+.IP
+The default value in this file is the minimum of [3% of free pages, 8MiB]
+expressed as KiB.
+The default is intended to provide enough for the superuser
+to log in and kill a process, if necessary,
+under the default overcommit 'guess' mode (i.e., 0 in
+.IR /proc/sys/vm/overcommit_memory ).
+.IP
+Systems running in "overcommit never" mode (i.e., 2 in
+.IR /proc/sys/vm/overcommit_memory )
+should increase the value in this file to account
+for the full virtual memory size of the programs used to recover (e.g.,
+.BR login (1)
+.BR ssh (1),
+and
+.BR top (1))
+Otherwise, the superuser may not be able to log in to recover the system.
+For example, on x86-64 a suitable value is 131072 (128MiB reserved).
+.IP
+Changing the value in this file takes effect whenever
+an application requests memory.
+.TP
+.IR /proc/sys/vm/compact_memory " (since Linux 2.6.35)"
+When 1 is written to this file, all zones are compacted such that free
+memory is available in contiguous blocks where possible.
+The effect of this action can be seen by examining
+.IR /proc/buddyinfo .
+.IP
+Present only if the kernel was configured with
+.BR CONFIG_COMPACTION .
+.TP
+.IR /proc/sys/vm/drop_caches " (since Linux 2.6.16)"
+Writing to this file causes the kernel to drop clean caches, dentries, and
+inodes from memory, causing that memory to become free.
+This can be useful for memory management testing and
+performing reproducible filesystem benchmarks.
+Because writing to this file causes the benefits of caching to be lost,
+it can degrade overall system performance.
+.IP
+To free pagecache, use:
+.IP
+.in +4n
+.EX
+echo 1 > /proc/sys/vm/drop_caches
+.EE
+.in
+.IP
+To free dentries and inodes, use:
+.IP
+.in +4n
+.EX
+echo 2 > /proc/sys/vm/drop_caches
+.EE
+.in
+.IP
+To free pagecache, dentries, and inodes, use:
+.IP
+.in +4n
+.EX
+echo 3 > /proc/sys/vm/drop_caches
+.EE
+.in
+.IP
+Because writing to this file is a nondestructive operation and dirty objects
+are not freeable, the
+user should run
+.BR sync (1)
+first.
+.TP
+.IR  /proc/sys/vm/sysctl_hugetlb_shm_group " (since Linux 2.6.7)"
+This writable file contains a group ID that is allowed
+to allocate memory using huge pages.
+If a process has a filesystem group ID or any supplementary group ID that
+matches this group ID,
+then it can make huge-page allocations without holding the
+.B CAP_IPC_LOCK
+capability; see
+.BR memfd_create (2),
+.BR mmap (2),
+and
+.BR shmget (2).
+.TP
+.IR /proc/sys/vm/legacy_va_layout " (since Linux 2.6.9)"
+.\" The following is from Documentation/filesystems/proc.txt
+If nonzero, this disables the new 32-bit memory-mapping layout;
+the kernel will use the legacy (2.4) layout for all processes.
+.TP
+.IR /proc/sys/vm/memory_failure_early_kill " (since Linux 2.6.32)"
+.\" The following is based on the text in Documentation/sysctl/vm.txt
+Control how to kill processes when an uncorrected memory error
+(typically a 2-bit error in a memory module)
+that cannot be handled by the kernel
+is detected in the background by hardware.
+In some cases (like the page still having a valid copy on disk),
+the kernel will handle the failure
+transparently without affecting any applications.
+But if there is no other up-to-date copy of the data,
+it will kill processes to prevent any data corruptions from propagating.
+.IP
+The file has one of the following values:
+.RS
+.TP
+.B 1
+Kill all processes that have the corrupted-and-not-reloadable page mapped
+as soon as the corruption is detected.
+Note that this is not supported for a few types of pages,
+such as kernel internally
+allocated data or the swap cache, but works for the majority of user pages.
+.TP
+.B 0
+Unmap the corrupted page from all processes and kill a process
+only if it tries to access the page.
+.RE
+.IP
+The kill is performed using a
+.B SIGBUS
+signal with
+.I si_code
+set to
+.BR BUS_MCEERR_AO .
+Processes can handle this if they want to; see
+.BR sigaction (2)
+for more details.
+.IP
+This feature is active only on architectures/platforms with advanced machine
+check handling and depends on the hardware capabilities.
+.IP
+Applications can override the
+.I memory_failure_early_kill
+setting individually with the
+.BR prctl (2)
+.B PR_MCE_KILL
+operation.
+.IP
+Present only if the kernel was configured with
+.BR CONFIG_MEMORY_FAILURE .
+.TP
+.IR /proc/sys/vm/memory_failure_recovery " (since Linux 2.6.32)"
+.\" The following is based on the text in Documentation/sysctl/vm.txt
+Enable memory failure recovery (when supported by the platform).
+.RS
+.TP
+.B 1
+Attempt recovery.
+.TP
+.B 0
+Always panic on a memory failure.
+.RE
+.IP
+Present only if the kernel was configured with
+.BR CONFIG_MEMORY_FAILURE .
+.TP
+.IR /proc/sys/vm/oom_dump_tasks " (since Linux 2.6.25)"
+.\" The following is from Documentation/sysctl/vm.txt
+Enables a system-wide task dump (excluding kernel threads) to be
+produced when the kernel performs an OOM-killing.
+The dump includes the following information
+for each task (thread, process):
+thread ID, real user ID, thread group ID (process ID),
+virtual memory size, resident set size,
+the CPU that the task is scheduled on,
+oom_adj score (see the description of
+.IR /proc/ pid /oom_adj ),
+and command name.
+This is helpful to determine why the OOM-killer was invoked
+and to identify the rogue task that caused it.
+.IP
+If this contains the value zero, this information is suppressed.
+On very large systems with thousands of tasks,
+it may not be feasible to dump the memory state information for each one.
+Such systems should not be forced to incur a performance penalty in
+OOM situations when the information may not be desired.
+.IP
+If this is set to nonzero, this information is shown whenever the
+OOM-killer actually kills a memory-hogging task.
+.IP
+The default value is 0.
+.TP
+.IR /proc/sys/vm/oom_kill_allocating_task " (since Linux 2.6.24)"
+.\" The following is from Documentation/sysctl/vm.txt
+This enables or disables killing the OOM-triggering task in
+out-of-memory situations.
+.IP
+If this is set to zero, the OOM-killer will scan through the entire
+tasklist and select a task based on heuristics to kill.
+This normally selects a rogue memory-hogging task that
+frees up a large amount of memory when killed.
+.IP
+If this is set to nonzero, the OOM-killer simply kills the task that
+triggered the out-of-memory condition.
+This avoids a possibly expensive tasklist scan.
+.IP
+If
+.I /proc/sys/vm/panic_on_oom
+is nonzero, it takes precedence over whatever value is used in
+.IR /proc/sys/vm/oom_kill_allocating_task .
+.IP
+The default value is 0.
+.TP
+.IR /proc/sys/vm/overcommit_kbytes " (since Linux 3.14)"
+.\" commit 49f0ce5f92321cdcf741e35f385669a421013cb7
+This writable file provides an alternative to
+.I /proc/sys/vm/overcommit_ratio
+for controlling the
+.I CommitLimit
+when
+.I /proc/sys/vm/overcommit_memory
+has the value 2.
+It allows the amount of memory overcommitting to be specified as
+an absolute value (in kB),
+rather than as a percentage, as is done with
+.IR overcommit_ratio .
+This allows for finer-grained control of
+.I CommitLimit
+on systems with extremely large memory sizes.
+.IP
+Only one of
+.I overcommit_kbytes
+or
+.I overcommit_ratio
+can have an effect:
+if
+.I overcommit_kbytes
+has a nonzero value, then it is used to calculate
+.IR CommitLimit ,
+otherwise
+.I overcommit_ratio
+is used.
+Writing a value to either of these files causes the
+value in the other file to be set to zero.
+.TP
+.I /proc/sys/vm/overcommit_memory
+This file contains the kernel virtual memory accounting mode.
+Values are:
+.RS
+.IP
+0: heuristic overcommit (this is the default)
+.br
+1: always overcommit, never check
+.br
+2: always check, never overcommit
+.RE
+.IP
+In mode 0, calls of
+.BR mmap (2)
+with
+.B MAP_NORESERVE
+are not checked, and the default check is very weak,
+leading to the risk of getting a process "OOM-killed".
+.IP
+In mode 1, the kernel pretends there is always enough memory,
+until memory actually runs out.
+One use case for this mode is scientific computing applications
+that employ large sparse arrays.
+Before Linux 2.6.0, any nonzero value implies mode 1.
+.IP
+In mode 2 (available since Linux 2.6), the total virtual address space
+that can be allocated
+.RI ( CommitLimit
+in
+.IR /proc/meminfo )
+is calculated as
+.IP
+.in +4n
+.EX
+CommitLimit = (total_RAM \- total_huge_TLB) *
+	      overcommit_ratio / 100 + total_swap
+.EE
+.in
+.IP
+where:
+.RS
+.IP \[bu] 3
+.I total_RAM
+is the total amount of RAM on the system;
+.IP \[bu]
+.I total_huge_TLB
+is the amount of memory set aside for huge pages;
+.IP \[bu]
+.I overcommit_ratio
+is the value in
+.IR /proc/sys/vm/overcommit_ratio ;
+and
+.IP \[bu]
+.I total_swap
+is the amount of swap space.
+.RE
+.IP
+For example, on a system with 16 GB of physical RAM, 16 GB
+of swap, no space dedicated to huge pages, and an
+.I overcommit_ratio
+of 50, this formula yields a
+.I CommitLimit
+of 24 GB.
+.IP
+Since Linux 3.14, if the value in
+.I /proc/sys/vm/overcommit_kbytes
+is nonzero, then
+.I CommitLimit
+is instead calculated as:
+.IP
+.in +4n
+.EX
+CommitLimit = overcommit_kbytes + total_swap
+.EE
+.in
+.IP
+See also the description of
+.I /proc/sys/vm/admin_reserve_kbytes
+and
+.IR /proc/sys/vm/user_reserve_kbytes .
+.TP
+.IR /proc/sys/vm/overcommit_ratio " (since Linux 2.6.0)"
+This writable file defines a percentage by which memory
+can be overcommitted.
+The default value in the file is 50.
+See the description of
+.IR /proc/sys/vm/overcommit_memory .
+.TP
+.IR /proc/sys/vm/panic_on_oom " (since Linux 2.6.18)"
+.\" The following is adapted from Documentation/sysctl/vm.txt
+This enables or disables a kernel panic in
+an out-of-memory situation.
+.IP
+If this file is set to the value 0,
+the kernel's OOM-killer will kill some rogue process.
+Usually, the OOM-killer is able to kill a rogue process and the
+system will survive.
+.IP
+If this file is set to the value 1,
+then the kernel normally panics when out-of-memory happens.
+However, if a process limits allocations to certain nodes
+using memory policies
+.RB ( mbind (2)
+.BR MPOL_BIND )
+or cpusets
+.RB ( cpuset (7))
+and those nodes reach memory exhaustion status,
+one process may be killed by the OOM-killer.
+No panic occurs in this case:
+because other nodes' memory may be free,
+this means the system as a whole may not have reached
+an out-of-memory situation yet.
+.IP
+If this file is set to the value 2,
+the kernel always panics when an out-of-memory condition occurs.
+.IP
+The default value is 0.
+1 and 2 are for failover of clustering.
+Select either according to your policy of failover.
+.TP
+.I /proc/sys/vm/swappiness
+.\" The following is from Documentation/sysctl/vm.txt
+The value in this file controls how aggressively the kernel will swap
+memory pages.
+Higher values increase aggressiveness, lower values
+decrease aggressiveness.
+The default value is 60.
+.TP
+.IR /proc/sys/vm/user_reserve_kbytes " (since Linux 3.10)"
+.\" commit c9b1d0981fcce3d9976d7b7a56e4e0503bc610dd
+Specifies an amount of memory (in KiB) to reserve for user processes.
+This is intended to prevent a user from starting a single memory hogging
+process, such that they cannot recover (kill the hog).
+The value in this file has an effect only when
+.I /proc/sys/vm/overcommit_memory
+is set to 2 ("overcommit never" mode).
+In this case, the system reserves an amount of memory that is the minimum
+of [3% of current process size,
+.IR user_reserve_kbytes ].
+.IP
+The default value in this file is the minimum of [3% of free pages, 128MiB]
+expressed as KiB.
+.IP
+If the value in this file is set to zero,
+then a user will be allowed to allocate all free memory with a single process
+(minus the amount reserved by
+.IR /proc/sys/vm/admin_reserve_kbytes ).
+Any subsequent attempts to execute a command will result in
+"fork: Cannot allocate memory".
+.IP
+Changing the value in this file takes effect whenever
+an application requests memory.
+.TP
+.IR /proc/sys/vm/unprivileged_userfaultfd " (since Linux 5.2)"
+.\" cefdca0a86be517bc390fc4541e3674b8e7803b0
+This (writable) file exposes a flag that controls whether
+unprivileged processes are allowed to employ
+.BR userfaultfd (2).
+If this file has the value 1, then unprivileged processes may use
+.BR userfaultfd (2).
+If this file has the value 0, then only processes that have the
+.B CAP_SYS_PTRACE
+capability may employ
+.BR userfaultfd (2).
+The default value in this file is 1.
+.SH SEE ALSO
+.BR proc (5),
+.BR proc_sys (5)
diff --git a/man/man5/proc_sysrq-trigger.5 b/man/man5/proc_sysrq-trigger.5
new file mode 100644
index 000000000..576569262
--- /dev/null
+++ b/man/man5/proc_sysrq-trigger.5
@@ -0,0 +1,25 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sysrq-trigger 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sysrq\-trigger \- SysRq function
+.SH DESCRIPTION
+.TP
+.IR /proc/sysrq\-trigger " (since Linux 2.4.21)"
+Writing a character to this file triggers the same SysRq function as
+typing ALT-SysRq-<character> (see the description of
+.IR /proc/sys/kernel/sysrq ).
+This file is normally writable only by
+.IR root .
+For further details see the Linux kernel source file
+.I Documentation/admin\-guide/sysrq.rst
+.\" commit 9d85025b0418163fae079c9ba8f8445212de8568
+(or
+.I Documentation/sysrq.txt
+before Linux 4.10).
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_sysvipc.5 b/man/man5/proc_sysvipc.5
new file mode 100644
index 000000000..f9789af02
--- /dev/null
+++ b/man/man5/proc_sysvipc.5
@@ -0,0 +1,25 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_sysvipc 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/sysvipc/ \- System V IPC
+.SH DESCRIPTION
+.TP
+.I /proc/sysvipc/
+Subdirectory containing the pseudo-files
+.IR msg ", " sem " and " shm "."
+These files list the System V Interprocess Communication (IPC) objects
+(respectively: message queues, semaphores, and shared memory)
+that currently exist on the system,
+providing similar information to that available via
+.BR ipcs (1).
+These files have headers and are formatted (one IPC object per line)
+for easy understanding.
+.BR sysvipc (7)
+provides further background on the information shown by these files.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_thread-self.5 b/man/man5/proc_thread-self.5
new file mode 100644
index 000000000..2c760e97e
--- /dev/null
+++ b/man/man5/proc_thread-self.5
@@ -0,0 +1 @@
+.so man5/proc_pid_task.5
diff --git a/man/man5/proc_tid.5 b/man/man5/proc_tid.5
new file mode 100644
index 000000000..2c760e97e
--- /dev/null
+++ b/man/man5/proc_tid.5
@@ -0,0 +1 @@
+.so man5/proc_pid_task.5
diff --git a/man/man5/proc_tid_children.5 b/man/man5/proc_tid_children.5
new file mode 100644
index 000000000..5c5466e02
--- /dev/null
+++ b/man/man5/proc_tid_children.5
@@ -0,0 +1,37 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_tid_children 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/tid/children \- child tasks
+.SH DESCRIPTION
+.TP
+.IR /proc/ tid /children " (since Linux 3.5)"
+.\" commit 818411616baf46ceba0cff6f05af3a9b294734f7
+A space-separated list of child tasks of this task.
+Each child task is represented by its TID.
+.IP
+.\" see comments in get_children_pid() in fs/proc/array.c
+This option is intended for use by the checkpoint-restore (CRIU) system,
+and reliably provides a list of children only if all of the child processes
+are stopped or frozen.
+It does not work properly if children of the target task exit while
+the file is being read!
+Exiting children may cause non-exiting children to be omitted from the list.
+This makes this interface even more unreliable than classic PID-based
+approaches if the inspected task and its children aren't frozen,
+and most code should probably not use this interface.
+.IP
+Until Linux 4.2, the presence of this file was governed by the
+.B CONFIG_CHECKPOINT_RESTORE
+kernel configuration option.
+Since Linux 4.2,
+.\" commit 2e13ba54a2682eea24918b87ad3edf70c2cf085b
+it is governed by the
+.B CONFIG_PROC_CHILDREN
+option.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_timer_list.5 b/man/man5/proc_timer_list.5
new file mode 100644
index 000000000..da437d4d1
--- /dev/null
+++ b/man/man5/proc_timer_list.5
@@ -0,0 +1,18 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_timer_list 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/timer_list \- pending timers
+.SH DESCRIPTION
+.TP
+.IR /proc/timer_list " (since Linux 2.6.21)"
+.\" commit 289f480af87e45f7a6de6ba9b4c061c2e259fe98
+This read-only file exposes a list of all currently pending
+(high-resolution) timers,
+all clock-event sources, and their parameters in a human-readable form.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_timer_stats.5 b/man/man5/proc_timer_stats.5
new file mode 100644
index 000000000..0c9f45978
--- /dev/null
+++ b/man/man5/proc_timer_stats.5
@@ -0,0 +1,117 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_timer_stats 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/timer_stats \- timer statistics
+.SH DESCRIPTION
+.TP
+.IR /proc/timer_stats " (from  Linux 2.6.21 until Linux 4.10)"
+.\" commit 82f67cd9fca8c8762c15ba7ed0d5747588c1e221
+.\"	Date:   Fri Feb 16 01:28:13 2007 -0800
+.\" Text largely derived from Documentation/timers/timer_stats.txt
+.\" removed in commit dfb4357da6ddbdf57d583ba64361c9d792b0e0b1
+.\"     Date:   Wed Feb 8 11:26:59 2017 -0800
+This is a debugging facility to make timer (ab)use in a Linux
+system visible to kernel and user-space developers.
+It can be used by kernel and user-space developers to verify that
+their code does not make undue use of timers.
+The goal is to avoid unnecessary wakeups,
+thereby optimizing power consumption.
+.IP
+If enabled in the kernel
+.RB ( CONFIG_TIMER_STATS ),
+but not used,
+it has almost zero run-time overhead and a relatively small
+data-structure overhead.
+Even if collection is enabled at run time, overhead is low:
+all the locking is per-CPU and lookup is hashed.
+.IP
+The
+.I /proc/timer_stats
+file is used both to control sampling facility and to read out the
+sampled information.
+.IP
+The
+.I timer_stats
+functionality is inactive on bootup.
+A sampling period can be started using the following command:
+.IP
+.in +4n
+.EX
+# echo 1 > /proc/timer_stats
+.EE
+.in
+.IP
+The following command stops a sampling period:
+.IP
+.in +4n
+.EX
+# echo 0 > /proc/timer_stats
+.EE
+.in
+.IP
+The statistics can be retrieved by:
+.IP
+.in +4n
+.EX
+$ cat /proc/timer_stats
+.EE
+.in
+.IP
+While sampling is enabled, each readout from
+.I /proc/timer_stats
+will see
+newly updated statistics.
+Once sampling is disabled, the sampled information
+is kept until a new sample period is started.
+This allows multiple readouts.
+.IP
+Sample output from
+.IR /proc/timer_stats :
+.IP
+.in +4n
+.EX
+.RB $ " cat /proc/timer_stats"
+Timer Stats Version: v0.3
+Sample period: 1.764 s
+Collection: active
+  255,     0 swapper/3        hrtimer_start_range_ns (tick_sched_timer)
+   71,     0 swapper/1        hrtimer_start_range_ns (tick_sched_timer)
+   58,     0 swapper/0        hrtimer_start_range_ns (tick_sched_timer)
+    4,  1694 gnome\-shell      mod_delayed_work_on (delayed_work_timer_fn)
+   17,     7 rcu_sched        rcu_gp_kthread (process_timeout)
+\&...
+    1,  4911 kworker/u16:0    mod_delayed_work_on (delayed_work_timer_fn)
+   1D,  2522 kworker/0:0      queue_delayed_work_on (delayed_work_timer_fn)
+1029 total events, 583.333 events/sec
+.EE
+.in
+.IP
+The output columns are:
+.RS
+.IP [1] 5
+a count of the number of events,
+optionally (since Linux 2.6.23) followed by the letter \[aq]D\[aq]
+.\" commit c5c061b8f9726bc2c25e19dec227933a13d1e6b7 deferrable timers
+if this is a deferrable timer;
+.IP [2]
+the PID of the process that initialized the timer;
+.IP [3]
+the name of the process that initialized the timer;
+.IP [4]
+the function where the timer was initialized; and
+(in parentheses)
+the callback function that is associated with the timer.
+.RE
+.IP
+During the Linux 4.11 development cycle,
+this file  was removed because of security concerns,
+as it exposes information across namespaces.
+Furthermore, it is possible to obtain
+the same information via in-kernel tracing facilities such as ftrace.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_tty.5 b/man/man5/proc_tty.5
new file mode 100644
index 000000000..e5b48cd78
--- /dev/null
+++ b/man/man5/proc_tty.5
@@ -0,0 +1,16 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_tty 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/tty/ \- tty
+.SH DESCRIPTION
+.TP
+.I /proc/tty/
+Subdirectory containing the pseudo-files and subdirectories for
+tty drivers and line disciplines.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_uptime.5 b/man/man5/proc_uptime.5
new file mode 100644
index 000000000..aa08d08a2
--- /dev/null
+++ b/man/man5/proc_uptime.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_uptime 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/uptime \- system uptime
+.SH DESCRIPTION
+.TP
+.I /proc/uptime
+This file contains two numbers (values in seconds): the uptime of the
+system (including time spent in suspend) and the amount of time spent
+in the idle process.
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_version.5 b/man/man5/proc_version.5
new file mode 100644
index 000000000..60e591984
--- /dev/null
+++ b/man/man5/proc_version.5
@@ -0,0 +1,27 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_version 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/version \- kernel version
+.SH DESCRIPTION
+.TP
+.I /proc/version
+This string identifies the kernel version that is currently running.
+It includes the contents of
+.IR /proc/sys/kernel/ostype ,
+.IR /proc/sys/kernel/osrelease ,
+and
+.IR /proc/sys/kernel/version .
+For example:
+.IP
+.in +4n
+.EX
+Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994
+.EE
+.in
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_vmstat.5 b/man/man5/proc_vmstat.5
new file mode 100644
index 000000000..083cc1565
--- /dev/null
+++ b/man/man5/proc_vmstat.5
@@ -0,0 +1,702 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_vmstat 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/vmstat \- virtual memory statistics
+.SH DESCRIPTION
+.TP
+.IR /proc/vmstat " (since Linux 2.6.0)"
+This file displays various virtual memory statistics.
+Each line of this file contains a single name-value pair,
+delimited by white space.
+Some lines are present only if the kernel was configured with
+suitable options.
+(In some cases, the options required for particular files have changed
+across kernel versions, so they are not listed here.
+Details can be found by consulting the kernel source code.)
+The following fields may be present:
+.\" FIXME We need explanations for each of the following fields...
+.RS
+.TP
+.IR nr_free_pages " (since Linux 2.6.31)"
+.\" commit d23ad42324cc4378132e51f2fc5c9ba6cbe75182
+.TP
+.IR nr_alloc_batch " (since Linux 3.12)"
+.\" commit 81c0a2bb515fd4daae8cab64352877480792b515
+.TP
+.IR nr_inactive_anon " (since Linux 2.6.28)"
+.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db
+.TP
+.IR nr_active_anon " (since Linux 2.6.28)"
+.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db
+.TP
+.IR nr_inactive_file " (since Linux 2.6.28)"
+.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db
+.TP
+.IR nr_active_file " (since Linux 2.6.28)"
+.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db
+.TP
+.IR nr_unevictable " (since Linux 2.6.28)"
+.\" commit 7b854121eb3e5ba0241882ff939e2c485228c9c5
+.TP
+.IR nr_mlock " (since Linux 2.6.28)"
+.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820
+.TP
+.IR nr_anon_pages " (since Linux 2.6.18)"
+.\" commit f3dbd34460ff54962d3e3244b6bcb7f5295356e6
+.TP
+.IR nr_mapped " (since Linux 2.6.0)"
+.TP
+.IR nr_file_pages " (since Linux 2.6.18)"
+.\" commit 347ce434d57da80fd5809c0c836f206a50999c26
+.TP
+.IR nr_dirty " (since Linux 2.6.0)"
+.TP
+.IR nr_writeback " (since Linux 2.6.0)"
+.TP
+.IR nr_slab_reclaimable " (since Linux 2.6.19)"
+.\" commit 972d1a7b140569084439a81265a0f15b74e924e0
+.\" Linux 2.6.0 had nr_slab
+.TP
+.IR nr_slab_unreclaimable " (since Linux 2.6.19)"
+.\" commit 972d1a7b140569084439a81265a0f15b74e924e0
+.TP
+.IR nr_page_table_pages " (since Linux 2.6.0)"
+.TP
+.IR nr_kernel_stack " (since Linux 2.6.32)"
+.\" commit c6a7f5728a1db45d30df55a01adc130b4ab0327c
+Amount of memory allocated to kernel stacks.
+.TP
+.IR nr_unstable " (since Linux 2.6.0)"
+.TP
+.IR nr_bounce " (since Linux 2.6.12)"
+.\" commit edfbe2b0038723e5699ab22695ccd62b5542a5c1
+.TP
+.IR nr_vmscan_write " (since Linux 2.6.19)"
+.\" commit e129b5c23c2b471d47f1c5d2b8b193fc2034af43
+.TP
+.IR nr_vmscan_immediate_reclaim " (since Linux 3.2)"
+.\" commit 49ea7eb65e7c5060807fb9312b1ad4c3eab82e2c
+.TP
+.IR nr_writeback_temp " (since Linux 2.6.26)"
+.\" commit fc3ba692a4d19019387c5acaea63131f9eab05dd
+.TP
+.IR nr_isolated_anon " (since Linux 2.6.32)"
+.\" commit a731286de62294b63d8ceb3c5914ac52cc17e690
+.TP
+.IR nr_isolated_file " (since Linux 2.6.32)"
+.\" commit a731286de62294b63d8ceb3c5914ac52cc17e690
+.TP
+.IR nr_shmem " (since Linux 2.6.32)"
+.\" commit 4b02108ac1b3354a22b0d83c684797692efdc395
+Pages used by shmem and
+.BR tmpfs (5).
+.TP
+.IR nr_dirtied " (since Linux 2.6.37)"
+.\" commit ea941f0e2a8c02ae876cd73deb4e1557248f258c
+.TP
+.IR nr_written " (since Linux 2.6.37)"
+.\" commit ea941f0e2a8c02ae876cd73deb4e1557248f258c
+.TP
+.IR nr_pages_scanned " (since Linux 3.17)"
+.\" commit 0d5d823ab4e608ec7b52ac4410de4cb74bbe0edd
+.TP
+.IR numa_hit " (since Linux 2.6.18)"
+.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_NUMA .
+.TP
+.IR numa_miss " (since Linux 2.6.18)"
+.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_NUMA .
+.TP
+.IR numa_foreign " (since Linux 2.6.18)"
+.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_NUMA .
+.TP
+.IR numa_interleave " (since Linux 2.6.18)"
+.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_NUMA .
+.TP
+.IR numa_local " (since Linux 2.6.18)"
+.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_NUMA .
+.TP
+.IR numa_other " (since Linux 2.6.18)"
+.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_NUMA .
+.TP
+.IR workingset_refault " (since Linux 3.15)"
+.\" commit a528910e12ec7ee203095eb1711468a66b9b60b0
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR workingset_activate " (since Linux 3.15)"
+.\" commit a528910e12ec7ee203095eb1711468a66b9b60b0
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR workingset_nodereclaim " (since Linux 3.15)"
+.\" commit 449dd6984d0e47643c04c807f609dd56d48d5bcc
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR nr_anon_transparent_hugepages " (since Linux 2.6.38)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR nr_free_cma " (since Linux 3.7)"
+.\" commit d1ce749a0db12202b711d1aba1d29e823034648d
+Number of free CMA (Contiguous Memory Allocator) pages.
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR nr_dirty_threshold " (since Linux 2.6.37)"
+.\" commit 79da826aee6a10902ef411bc65864bd02102fa83
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR nr_dirty_background_threshold " (since Linux 2.6.37)"
+.\" commit 79da826aee6a10902ef411bc65864bd02102fa83
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgpgin " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgpgout " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pswpin " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pswpout " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgalloc_dma " (since Linux 2.6.5)"
+.\" Linux 2.6.0 had pgalloc
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgalloc_dma32 " (since Linux 2.6.16)"
+.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgalloc_normal " (since Linux 2.6.5)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgalloc_high " (since Linux 2.6.5)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HIGHMEM .
+.TP
+.IR pgalloc_movable " (since Linux 2.6.23)"
+.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgfree " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgactivate " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgdeactivate " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgfault " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgmajfault " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgrefill_dma " (since Linux 2.6.5)"
+.\" Linux 2.6.0 had pgrefill
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgrefill_dma32 " (since Linux 2.6.16)"
+.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgrefill_normal " (since Linux 2.6.5)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgrefill_high " (since Linux 2.6.5)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HIGHMEM .
+.TP
+.IR pgrefill_movable " (since Linux 2.6.23)"
+.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.\" Formerly there were
+.\"     pgsteal_high
+.\"     pgsteal_normal
+.\"     pgsteal_dma32
+.\"     pgsteal_dma
+.\" These were split out into pgsteal_kswapd* and pgsteal_direct*
+.\" in commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.TP
+.IR pgsteal_kswapd_dma " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" Linux 2.6.0 had pgsteal
+.\" Present only if the kernel was configured with
+.\" .\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgsteal_kswapd_dma32 " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgsteal_kswapd_normal " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgsteal_kswapd_high " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HIGHMEM .
+.TP
+.IR pgsteal_kswapd_movable " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.I pgsteal_direct_dma
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgsteal_direct_dma32 " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgsteal_direct_normal " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgsteal_direct_high " (since Linux 3.4)"
+.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HIGHMEM .
+.TP
+.IR pgsteal_direct_movable " (since Linux 2.6.23)"
+.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.I pgscan_kswapd_dma
+.\" Linux 2.6.0 had pgscan
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgscan_kswapd_dma32 " (since Linux 2.6.16)"
+.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgscan_kswapd_normal " (since Linux 2.6.5)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.I pgscan_kswapd_high
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HIGHMEM .
+.TP
+.IR pgscan_kswapd_movable " (since Linux 2.6.23)"
+.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.I pgscan_direct_dma
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgscan_direct_dma32 " (since Linux 2.6.16)"
+.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.I pgscan_direct_normal
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.I pgscan_direct_high
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HIGHMEM .
+.TP
+.IR pgscan_direct_movable " (since Linux 2.6.23)"
+.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgscan_direct_throttle " (since Linux 3.6)"
+.\" commit 68243e76ee343d63c6cf76978588a885951e2818
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR zone_reclaim_failed " (since linux 2.6.31)"
+.\" commit 24cf72518c79cdcda486ed26074ff8151291cf65
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_NUMA .
+.TP
+.IR pginodesteal " (since linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR slabs_scanned " (since linux 2.6.5)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR kswapd_inodesteal " (since linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR kswapd_low_wmark_hit_quickly " (since Linux 2.6.33)"
+.\" commit bb3ab596832b920c703d1aea1ce76d69c0f71fb7
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR kswapd_high_wmark_hit_quickly " (since Linux 2.6.33)"
+.\" commit bb3ab596832b920c703d1aea1ce76d69c0f71fb7
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pageoutrun " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR allocstall " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR pgrotated " (since Linux 2.6.0)"
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR drop_pagecache " (since Linux 3.15)"
+.\" commit 5509a5d27b971a90b940e148ca9ca53312e4fa7a
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR drop_slab " (since Linux 3.15)"
+.\" commit 5509a5d27b971a90b940e148ca9ca53312e4fa7a
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR numa_pte_updates " (since Linux 3.8)"
+.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_NUMA_BALANCING .
+.TP
+.IR numa_huge_pte_updates " (since Linux 3.13)"
+.\" commit 72403b4a0fbdf433c1fe0127e49864658f6f6468
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_NUMA_BALANCING .
+.TP
+.IR numa_hint_faults " (since Linux 3.8)"
+.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_NUMA_BALANCING .
+.TP
+.IR numa_hint_faults_local " (since Linux 3.8)"
+.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_NUMA_BALANCING .
+.TP
+.IR numa_pages_migrated " (since Linux 3.8)"
+.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_NUMA_BALANCING
+.\" and
+.\" .BR CONFIG_NUMA_BALANCING .
+.TP
+.IR pgmigrate_success " (since Linux 3.8)"
+.\" commit 5647bc293ab15f66a7b1cda850c5e9d162a6c7c2
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_MIGRATION .
+.TP
+.IR pgmigrate_fail " (since Linux 3.8)"
+.\" commit 5647bc293ab15f66a7b1cda850c5e9d162a6c7c2
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_MIGRATION .
+.TP
+.IR compact_migrate_scanned " (since Linux 3.8)"
+.\" commit 397487db696cae0b026a474a5cd66f4e372995e6
+.\" Linux 3.8 dropped compact_blocks_moved, compact_pages_moved, and
+.\"           compact_pagemigrate_failed
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_COMPACTION .
+.TP
+.IR compact_free_scanned " (since Linux 3.8)"
+.\" commit 397487db696cae0b026a474a5cd66f4e372995e6
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_COMPACTION .
+.TP
+.IR compact_isolated " (since Linux 3.8)"
+.\" commit 397487db696cae0b026a474a5cd66f4e372995e6
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_COMPACTION .
+.TP
+.IR compact_stall " (since Linux 2.6.35)"
+.\" commit 56de7263fcf3eb10c8dcdf8d59a9cec831795f3f
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_COMPACTION .
+.TP
+.IR compact_fail " (since Linux 2.6.35)"
+.\" commit 56de7263fcf3eb10c8dcdf8d59a9cec831795f3f
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_COMPACTION .
+.TP
+.IR compact_success " (since Linux 2.6.35)"
+.\" commit 56de7263fcf3eb10c8dcdf8d59a9cec831795f3f
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_COMPACTION .
+.TP
+.IR htlb_buddy_alloc_success " (since Linux 2.6.26)"
+.\" commit 3b1163006332302117b1b2acf226d4014ff46525
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HUGETLB_PAGE .
+.TP
+.IR htlb_buddy_alloc_fail " (since Linux 2.6.26)"
+.\" commit 3b1163006332302117b1b2acf226d4014ff46525
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_HUGETLB_PAGE .
+.TP
+.IR unevictable_pgs_culled " (since Linux 2.6.28)"
+.\" commit bbfd28eee9fbd73e780b19beb3dc562befbb94fa
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR unevictable_pgs_scanned " (since Linux 2.6.28)"
+.\" commit bbfd28eee9fbd73e780b19beb3dc562befbb94fa
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR unevictable_pgs_rescued " (since Linux 2.6.28)"
+.\" commit bbfd28eee9fbd73e780b19beb3dc562befbb94fa
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR unevictable_pgs_mlocked " (since Linux 2.6.28)"
+.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR unevictable_pgs_munlocked " (since Linux 2.6.28)"
+.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR unevictable_pgs_cleared " (since Linux 2.6.28)"
+.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.TP
+.IR unevictable_pgs_stranded " (since Linux 2.6.28)"
+.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS .
+.\" Linux 3.7 removed unevictable_pgs_mlockfreed
+.TP
+.IR thp_fault_alloc " (since Linux 2.6.39)"
+.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_TRANSPARENT_HUGEPAGE .
+.TP
+.IR thp_fault_fallback " (since Linux 2.6.39)"
+.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_TRANSPARENT_HUGEPAGE .
+.TP
+.IR thp_collapse_alloc " (since Linux 2.6.39)"
+.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_TRANSPARENT_HUGEPAGE .
+.TP
+.IR thp_collapse_alloc_failed " (since Linux 2.6.39)"
+.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_TRANSPARENT_HUGEPAGE .
+.TP
+.IR thp_split " (since Linux 2.6.39)"
+.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_TRANSPARENT_HUGEPAGE .
+.TP
+.IR thp_zero_page_alloc " (since Linux 3.8)"
+.\" commit d8a8e1f0da3d29d7268b3300c96a059d63901b76
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_TRANSPARENT_HUGEPAGE .
+.TP
+.IR thp_zero_page_alloc_failed " (since Linux 3.8)"
+.\" commit d8a8e1f0da3d29d7268b3300c96a059d63901b76
+See the kernel source file
+.IR Documentation/admin\-guide/mm/transhuge.rst .
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_TRANSPARENT_HUGEPAGE .
+.TP
+.IR balloon_inflate " (since Linux 3.18)"
+.\" commit 09316c09dde33aae14f34489d9e3d243ec0d5938
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_MEMORY_BALLOON .
+.TP
+.IR balloon_deflate " (since Linux 3.18)"
+.\" commit 09316c09dde33aae14f34489d9e3d243ec0d5938
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS
+.\" and
+.\" .BR CONFIG_MEMORY_BALLOON .
+.TP
+.IR balloon_migrate " (since Linux 3.18)"
+.\" commit 09316c09dde33aae14f34489d9e3d243ec0d5938
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_VM_EVENT_COUNTERS ,
+.\" .BR CONFIG_MEMORY_BALLOON ,
+.\" and
+.\" .BR CONFIG_BALLOON_COMPACTION .
+.TP
+.IR nr_tlb_remote_flush " (since Linux 3.12)"
+.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_DEBUG_TLBFLUSH
+.\" and
+.\" .BR CONFIG_SMP .
+.TP
+.IR nr_tlb_remote_flush_received " (since Linux 3.12)"
+.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_DEBUG_TLBFLUSH
+.\" and
+.\" .BR CONFIG_SMP .
+.TP
+.IR nr_tlb_local_flush_all " (since Linux 3.12)"
+.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_DEBUG_TLBFLUSH .
+.TP
+.IR nr_tlb_local_flush_one " (since Linux 3.12)"
+.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_DEBUG_TLBFLUSH .
+.TP
+.IR vmacache_find_calls " (since Linux 3.16)"
+.\" commit 4f115147ff802267d0aa41e361c5aa5bd933d896
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_DEBUG_VM_VMACACHE .
+.TP
+.IR vmacache_find_hits " (since Linux 3.16)"
+.\" commit 4f115147ff802267d0aa41e361c5aa5bd933d896
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_DEBUG_VM_VMACACHE .
+.TP
+.IR vmacache_full_flushes " (since Linux 3.19)"
+.\" commit f5f302e21257ebb0c074bbafc37606c26d28cc3d
+.\" Present only if the kernel was configured with
+.\" .BR CONFIG_DEBUG_VM_VMACACHE .
+.RE
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/proc_zoneinfo.5 b/man/man5/proc_zoneinfo.5
new file mode 100644
index 000000000..0c9ab3817
--- /dev/null
+++ b/man/man5/proc_zoneinfo.5
@@ -0,0 +1,17 @@
+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_zoneinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+/proc/zoneinfo \- memory zones
+.SH DESCRIPTION
+.TP
+.IR /proc/zoneinfo " (since Linux 2.6.13)"
+This file displays information about memory zones.
+This is useful for analyzing virtual memory behavior.
+.\" FIXME more should be said about /proc/zoneinfo
+.SH SEE ALSO
+.BR proc (5)
diff --git a/man/man5/procfs.5 b/man/man5/procfs.5
new file mode 100644
index 000000000..d8be74ac8
--- /dev/null
+++ b/man/man5/procfs.5
@@ -0,0 +1 @@
+.so man5/proc.5
diff --git a/man/man5/protocols.5 b/man/man5/protocols.5
new file mode 100644
index 000000000..a83d07576
--- /dev/null
+++ b/man/man5/protocols.5
@@ -0,0 +1,66 @@
+.\" Copyright (c) 1995 Martin Schulze <joey@infodrom.north.de>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1995-10-18  Martin Schulze  <joey@infodrom.north.de>
+.\"	* first released
+.\" 2002-09-22  Seth W. Klein  <sk@sethwklein.net>
+.\"     * protocol numbers are now assigned by the IANA
+.\"
+.TH protocols 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+protocols \- protocols definition file
+.SH DESCRIPTION
+This file is a plain ASCII file, describing the various DARPA internet
+protocols that are available from the TCP/IP subsystem.
+It should be
+consulted instead of using the numbers in the ARPA include files, or,
+even worse, just guessing them.
+These numbers will occur in the
+protocol field of any IP header.
+.P
+Keep this file untouched since changes would result in incorrect IP
+packages.
+Protocol numbers and names are specified by the IANA
+(Internet Assigned Numbers Authority).
+.\" .. by the DDN Network Information Center.
+.P
+Each line is of the following format:
+.P
+.RS
+.I protocol number aliases .\|.\|.
+.RE
+.P
+where the fields are delimited by spaces or tabs.
+Empty lines are ignored.
+If a line contains a hash mark (#), the hash mark and the part
+of the line following it are ignored.
+.P
+The field descriptions are:
+.TP
+.I protocol
+the native name for the protocol.
+For example
+.IR ip ,
+.IR tcp ,
+or
+.IR udp .
+.TP
+.I number
+the official number for this protocol as it will appear within the IP
+header.
+.TP
+.I aliases
+optional aliases for the protocol.
+.P
+This file might be distributed over a network using a network-wide
+naming service like Yellow Pages/NIS or BIND/Hesiod.
+.SH FILES
+.TP
+.I /etc/protocols
+The protocols definition file.
+.SH SEE ALSO
+.BR getprotoent (3)
+.P
+.UR http://www.iana.org\:/assignments\:/protocol\-numbers
+.UE
diff --git a/man/man5/repertoiremap.5 b/man/man5/repertoiremap.5
new file mode 100644
index 000000000..71c8a26a9
--- /dev/null
+++ b/man/man5/repertoiremap.5
@@ -0,0 +1,58 @@
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH repertoiremap 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+repertoiremap \- map symbolic character names to Unicode code points
+.SH DESCRIPTION
+A repertoire map defines mappings between symbolic character names
+(mnemonics) and Unicode code points when compiling a locale with
+.BR localedef (1).
+Using a repertoire map is optional, it is needed only when symbolic
+names are used instead of now preferred Unicode code points.
+.SS Syntax
+The repertoiremap file starts with a header that may consist of the
+following keywords:
+.TP
+.I comment_char
+is followed by a character that will be used as the
+comment character for the rest of the file.
+It defaults to the number sign (#).
+.TP
+.I escape_char
+is followed by a character that should be used as the escape character
+for the rest of the file to mark characters that should be interpreted
+in a special way.
+It defaults to the backslash (\e).
+.P
+The mapping section starts with the keyword
+.I CHARIDS
+in the first column.
+.P
+The mapping lines have the following form:
+.TP
+.I <symbolic-name> <code-point> comment
+This defines exactly one mapping,
+.I comment
+being optional.
+.P
+The mapping section ends with the string
+.IR "END CHARIDS" .
+.SH FILES
+.TP
+.I /usr/share/i18n/repertoiremaps
+Usual default repertoire map path.
+.SH STANDARDS
+POSIX.2.
+.SH NOTES
+Repertoire maps are deprecated in favor of Unicode code points.
+.SH EXAMPLES
+A mnemonic for the Euro sign can be defined as follows:
+.P
+.nf
+<Eu> <U20AC> EURO SIGN
+.fi
+.SH SEE ALSO
+.BR locale (1),
+.BR localedef (1),
+.BR charmap (5),
+.BR locale (5)
diff --git a/man/man5/resolv.conf.5 b/man/man5/resolv.conf.5
new file mode 100644
index 000000000..7efce605b
--- /dev/null
+++ b/man/man5/resolv.conf.5
@@ -0,0 +1,406 @@
+.\" Copyright (c) 1986 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Redistribution and use in source and binary forms are permitted
+.\" provided that the above copyright notice and this paragraph are
+.\" duplicated in all such forms and that any documentation,
+.\" advertising materials, and other materials related to such
+.\" distribution and use acknowledge that the software was developed
+.\" by the University of California, Berkeley.  The name of the
+.\" University may not be used to endorse or promote products derived
+.\" from this software without specific prior written permission.
+.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+.\" %%%LICENSE_END
+.\"
+.\"	@(#)resolver.5	5.9 (Berkeley) 12/14/89
+.\"	$Id: resolver.5,v 8.6 1999/05/21 00:01:02 vixie Exp $
+.\"
+.\" Added ndots remark by Bernhard R. Link - debian bug #182886
+.\"
+.TH resolv.conf 5 (date) "Linux man-pages (unreleased)"
+.UC 4
+.SH NAME
+resolv.conf \- resolver configuration file
+.SH SYNOPSIS
+.nf
+.B /etc/resolv.conf
+.fi
+.SH DESCRIPTION
+The
+.I resolver
+is a set of routines in the C library
+that provide access to the Internet Domain Name System (DNS).
+The resolver configuration file contains information that is read
+by the resolver routines the first time they are invoked by a process.
+The file is designed to be human readable and contains a list of
+keywords with values that provide various types of resolver information.
+The configuration file is considered a trusted source of DNS information;
+see the
+.B trust-ad
+option below for details.
+.P
+If this file does not exist, only the name server on the local machine
+will be queried, and the search list contains the local domain name
+determined from the hostname.
+.P
+The different configuration options are:
+.TP
+\fBnameserver\fP Name server IP address
+Internet address of a name server that the resolver should query,
+either an IPv4 address (in dot notation),
+or an IPv6 address in colon (and possibly dot) notation as per RFC 2373.
+Up to
+.B MAXNS
+(currently 3, see \fI<resolv.h>\fP) name servers may be listed,
+one per keyword.
+If there are multiple servers,
+the resolver library queries them in the order listed.
+If no \fBnameserver\fP entries are present,
+the default is to use the name server on the local machine.
+(The algorithm used is to try a name server, and if the query times out,
+try the next, until out of name servers,
+then repeat trying all the name servers
+until a maximum number of retries are made.)
+.TP
+\fBsearch\fP Search list for host-name lookup.
+By default, the search list contains one entry, the local domain name.
+It is determined from the local hostname returned by
+.BR gethostname (2);
+the local domain name is taken to be everything after the first
+\[aq].\[aq].
+Finally, if the hostname does not contain a \[aq].\[aq], the
+root domain is assumed as the local domain name.
+.IP
+This may be changed by listing the desired domain search path
+following the \fIsearch\fP keyword with spaces or tabs separating
+the names.
+Resolver queries having fewer than
+.I ndots
+dots (default is 1) in them will be attempted using each component
+of the search path in turn until a match is found.
+For environments with multiple subdomains please read
+.BI "options ndots:" n
+below to avoid man-in-the-middle attacks and unnecessary
+traffic for the root-dns-servers.
+.\" When having a resolv.conv with a line
+.\"  search subdomain.domain.tld domain.tld
+.\" and doing a hostlookup, for example by
+.\"  ping host.anothersubdomain
+.\" it sends dns-requests for
+.\"  host.anothersubdomain.
+.\"  host.anothersubdomain.subdomain.domain.tld.
+.\"  host.anothersubdomain.domain.tld.
+.\" thus not only causing unnecessary traffic for the root-dns-servers
+.\" but broadcasting information to the outside and making man-in-the-middle
+.\" attacks possible.
+Note that this process may be slow and will generate a lot of network
+traffic if the servers for the listed domains are not local,
+and that queries will time out if no server is available
+for one of the domains.
+.IP
+If there are multiple
+.B search
+directives, only the search list from the last instance is used.
+.IP
+In glibc 2.25 and earlier, the search list is limited to six domains
+with a total of 256 characters.
+Since glibc 2.26,
+.\" glibc commit 3f853f22c87f0b671c0366eb290919719fa56c0e
+the search list is unlimited.
+.IP
+The
+.B domain
+directive is an obsolete name for the
+.B search
+directive that handles one search list entry only.
+.TP
+\fBsortlist\fP
+This option allows addresses returned by
+.BR gethostbyname (3)
+to be sorted.
+A sortlist is specified by IP-address-netmask pairs.
+The netmask is
+optional and defaults to the natural netmask of the net.
+The IP address
+and optional network pairs are separated by slashes.
+Up to 10 pairs may
+be specified.
+Here is an example:
+.IP
+.in +4n
+sortlist 130.155.160.0/255.255.240.0 130.155.0.0
+.in
+.TP
+\fBoptions\fP
+Options allows certain internal resolver variables to be modified.
+The syntax is
+.RS
+.IP
+\fBoptions\fP \fIoption\fP \fI...\fP
+.P
+where \fIoption\fP is one of the following:
+.TP
+\fBdebug\fP
+.\" Since glibc 2.2?
+Sets
+.B RES_DEBUG
+in
+.I _res.options
+(effective only if glibc was built with debug support; see
+.BR resolver (3)).
+.TP
+.BI ndots: n
+.\" Since glibc 2.2
+Sets a threshold for the number of dots which
+must appear in a name given to
+.BR res_query (3)
+(see
+.BR resolver (3))
+before an \fIinitial absolute query\fP will be made.
+The default for
+\fIn\fP is 1, meaning that if there are any dots in a name, the name
+will be tried first as an absolute name before any \fIsearch list\fP
+elements are appended to it.
+The value for this option is silently capped to 15.
+.TP
+.BI timeout: n
+.\" Since glibc 2.2
+Sets the amount of time the resolver will wait for a
+response from a remote name server before retrying the
+query via a different name server.
+This may
+.B not
+be the total time taken by any resolver API call and there is no
+guarantee that a single resolver API call maps to a single timeout.
+Measured in seconds,
+the default is
+.B RES_TIMEOUT
+(currently 5, see \fI<resolv.h>\fP).
+The value for this option is silently capped to 30.
+.TP
+.BI attempts: n
+Sets the number of times the resolver will send a
+query to its name servers before giving up and returning
+an error to the calling application.
+The default is
+.B RES_DFLRETRY
+(currently 2, see \fI<resolv.h>\fP).
+The value for this option is silently capped to 5.
+.TP
+.B rotate
+.\" Since glibc 2.2
+Sets
+.B RES_ROTATE
+in
+.IR _res.options ,
+which causes round-robin selection of name servers from among those listed.
+This has the effect of spreading the query load among all listed servers,
+rather than having all clients try the first listed server first every time.
+.TP
+.B no\-aaaa (since glibc 2.36)
+.\" f282cdbe7f436c75864e5640a409a10485e9abb2
+Sets
+.B RES_NOAAAA
+in
+.IR _res.options ,
+which suppresses AAAA queries made by the stub resolver,
+including AAAA lookups triggered by NSS-based interfaces such as
+.BR getaddrinfo (3).
+Only DNS lookups are affected: IPv6 data in
+.BR hosts (5)
+is still used,
+.BR getaddrinfo (3)
+with
+.B AI_PASSIVE
+will still produce IPv6 addresses,
+and configured IPv6 name servers are still used.
+To produce correct Name Error (NXDOMAIN) results,
+AAAA queries are translated to A queries.
+This option is intended preliminary for diagnostic purposes,
+to rule out that AAAA DNS queries have adverse impact.
+It is incompatible with EDNS0 usage and DNSSEC validation by applications.
+.TP
+.B no\-check\-names
+.\" since glibc 2.2
+Sets
+.B RES_NOCHECKNAME
+in
+.IR _res.options ,
+which disables the modern BIND checking of incoming hostnames and
+mail names for invalid characters such as underscore (_), non-ASCII,
+or control characters.
+.TP
+.B inet6
+.\" Since glibc 2.2
+Sets
+.B RES_USE_INET6
+in
+.IR _res.options .
+This has the effect of trying an AAAA query before an A query inside the
+.BR gethostbyname (3)
+function, and of mapping IPv4 responses in IPv6 "tunneled form"
+if no AAAA records are found but an A record set exists.
+Since glibc 2.25,
+.\" b76e065991ec01299225d9da90a627ebe6c1ac97
+this option is deprecated; applications should use
+.BR getaddrinfo (3),
+rather than
+.BR gethostbyname (3).
+.TP
+.BR ip6\-bytestring " (since glibc 2.3.4 to glibc 2.24)"
+Sets
+.B RES_USEBSTRING
+in
+.IR _res.options .
+This causes reverse IPv6 lookups to be made using the bit-label format
+described in RFC\ 2673;
+if this option is not set (which is the default), then nibble format is used.
+This option was removed in glibc 2.25,
+since it relied on a backward-incompatible
+DNS extension that was never deployed on the Internet.
+.TP
+.BR ip6\-dotint / no\-ip6\-dotint " (glibc 2.3.4 to glibc 2.24)"
+Clear/set
+.B RES_NOIP6DOTINT
+in
+.IR _res.options .
+When this option is clear
+.RB ( ip6\-dotint ),
+reverse IPv6 lookups are made in the (deprecated)
+.I ip6.int
+zone;
+when this option is set
+.RB ( no\-ip6\-dotint ),
+reverse IPv6 lookups are made in the
+.I ip6.arpa
+zone by default.
+These options are available up to glibc 2.24, where
+.B no\-ip6\-dotint
+is the default.
+Since
+.B ip6\-dotint
+support long ago ceased to be available on the Internet,
+these options were removed in glibc 2.25.
+.TP
+.BR edns0 " (since glibc 2.6)"
+Sets
+.B RES_USE_EDNS0
+in
+.IR _res.options .
+This enables support for the DNS extensions described in RFC\ 2671.
+.TP
+.BR single\-request " (since glibc 2.10)"
+Sets
+.B RES_SNGLKUP
+in
+.IR _res.options .
+By default, glibc performs IPv4 and IPv6 lookups in parallel since
+glibc 2.9.
+Some appliance DNS servers
+cannot handle these queries properly and make the requests time out.
+This option disables the behavior and makes glibc perform the IPv6
+and IPv4 requests sequentially (at the cost of some slowdown of the
+resolving process).
+.TP
+.BR single\-request\-reopen " (since glibc 2.9)"
+Sets
+.B RES_SNGLKUPREOP
+in
+.IR _res.options .
+The resolver uses the same socket for the A and AAAA requests.
+Some hardware mistakenly sends back only one reply.
+When that happens the client system will sit and wait for the second reply.
+Turning this option on changes this behavior
+so that if two requests from the same port are not handled correctly it will
+close the socket and open a new one before sending the second request.
+.TP
+.BR no\-tld\-query " (since glibc 2.14)"
+Sets
+.B RES_NOTLDQUERY
+in
+.IR _res.options .
+This option causes
+.BR res_nsearch ()
+to not attempt to resolve an unqualified name
+as if it were a top level domain (TLD).
+This option can cause problems if the site has ``localhost'' as a TLD
+rather than having localhost on one or more elements of the search list.
+This option has no effect if neither RES_DEFNAMES or RES_DNSRCH is set.
+.TP
+.BR use\-vc " (since glibc 2.14)"
+Sets
+.B RES_USEVC
+in
+.IR _res.options .
+This option forces the use of TCP for DNS resolutions.
+.\" aef16cc8a4c670036d45590877d411a97f01e0cd
+.TP
+.BR no\-reload " (since glibc 2.26)"
+Sets
+.B RES_NORELOAD
+in
+.IR _res.options .
+This option disables automatic reloading of a changed configuration file.
+.TP
+.BR trust\-ad " (since glibc 2.31)"
+.\" 446997ff1433d33452b81dfa9e626b8dccf101a4
+Sets
+.B RES_TRUSTAD
+in
+.IR _res.options .
+This option controls the AD bit behavior of the stub resolver.
+If a validating resolver sets the AD bit in a response,
+it indicates that the data in the response was verified according
+to the DNSSEC protocol.
+In order to rely on the AD bit, the local system has to
+trust both the DNSSEC-validating resolver and the network path to it,
+which is why an explicit opt-in is required.
+If the
+.B trust\-ad
+option is active, the stub resolver sets the AD bit in outgoing DNS
+queries (to enable AD bit support), and preserves the AD bit in responses.
+Without this option, the AD bit is not set in queries,
+and it is always removed from responses before they are returned to the
+application.
+This means that applications can trust the AD bit in responses if the
+.B trust\-ad
+option has been set correctly.
+.IP
+In glibc 2.30 and earlier,
+the AD is not set automatically in queries,
+and is passed through unchanged to applications in responses.
+.RE
+.P
+The \fIsearch\fP keyword of a system's \fIresolv.conf\fP file can be
+overridden on a per-process basis by setting the environment variable
+.B LOCALDOMAIN
+to a space-separated list of search domains.
+.P
+The \fIoptions\fP keyword of a system's \fIresolv.conf\fP file can be
+amended on a per-process basis by setting the environment variable
+.B RES_OPTIONS
+to a space-separated list of resolver options
+as explained above under \fBoptions\fP.
+.P
+The keyword and value must appear on a single line, and the keyword
+(e.g., \fBnameserver\fP) must start the line.
+The value follows the keyword, separated by white space.
+.P
+Lines that contain a semicolon (;) or hash character (#)
+in the first column are treated as comments.
+.SH FILES
+.IR /etc/resolv.conf ,
+.I <resolv.h>
+.SH SEE ALSO
+.BR gethostbyname (3),
+.BR resolver (3),
+.BR host.conf (5),
+.BR hosts (5),
+.BR nsswitch.conf (5),
+.BR hostname (7),
+.BR named (8)
+.P
+Name Server Operations Guide for BIND
diff --git a/man/man5/resolver.5 b/man/man5/resolver.5
new file mode 100644
index 000000000..86104b96c
--- /dev/null
+++ b/man/man5/resolver.5
@@ -0,0 +1 @@
+.so man5/resolv.conf.5
diff --git a/man/man5/rpc.5 b/man/man5/rpc.5
new file mode 100644
index 000000000..f49924c6f
--- /dev/null
+++ b/man/man5/rpc.5
@@ -0,0 +1,83 @@
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\"
+.\" %%%LICENSE_START(BSD_ONELINE_CDROM)
+.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license)
+.\" %%%LICENSE_END
+.\"
+.\" @(#)rpc.5	2.2 88/08/03 4.0 RPCSRC; from 1.4 87/11/27 SMI;
+.TH rpc 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rpc \- RPC program number data base
+.SH SYNOPSIS
+.nf
+.B /etc/rpc
+.fi
+.SH DESCRIPTION
+The
+.I rpc
+file contains user readable names that
+can be used in place of RPC program numbers.
+Each line has the following information:
+.P
+.PD 0
+.IP \[bu] 3
+name of server for the RPC program
+.IP \[bu]
+RPC program number
+.IP \[bu]
+aliases
+.PD
+.P
+Items are separated by any number of blanks and/or
+tab characters.
+A \[aq]#\[aq] indicates the beginning of a comment; characters from
+the \[aq]#\[aq] to the end of the line are not interpreted by routines
+which search the file.
+.P
+Here is an example of the
+.I /etc/rpc
+file from the Sun RPC Source distribution.
+.P
+.in +4n
+.EX
+#
+# rpc 88/08/01 4.0 RPCSRC; from 1.12   88/02/07 SMI
+#
+portmapper      100000  portmap sunrpc
+rstatd          100001  rstat rstat_svc rup perfmeter
+rusersd         100002  rusers
+nfs             100003  nfsprog
+ypserv          100004  ypprog
+mountd          100005  mount showmount
+ypbind          100007
+walld           100008  rwall shutdown
+yppasswdd       100009  yppasswd
+etherstatd      100010  etherstat
+rquotad         100011  rquotaprog quota rquota
+sprayd          100012  spray
+3270_mapper     100013
+rje_mapper      100014
+selection_svc   100015  selnsvc
+database_svc    100016
+rexd            100017  rex
+alis            100018
+sched           100019
+llockmgr        100020
+nlockmgr        100021
+x25.inr         100022
+statmon         100023
+status          100024
+bootparam       100026
+ypupdated       100028  ypupdate
+keyserv         100029  keyserver
+tfsd            100037
+nsed            100038
+nsemntd         100039
+.EE
+.in
+.SH FILES
+.TP
+.I /etc/rpc
+RPC program number data base
+.SH SEE ALSO
+.BR getrpcent (3)
diff --git a/man/man5/securetty.5 b/man/man5/securetty.5
new file mode 100644
index 000000000..ec397df9b
--- /dev/null
+++ b/man/man5/securetty.5
@@ -0,0 +1,35 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sun Jul 25 11:06:27 1993 by Rik Faith (faith@cs.unc.edu)
+.TH securetty 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+securetty \- list of terminals on which root is allowed to login
+.SH DESCRIPTION
+The file
+.I /etc/securetty
+contains the names of terminals
+(one per line, without leading
+.IR /dev/ )
+which are considered secure for the transmission of certain authentication
+tokens.
+.P
+It is used by (some versions of)
+.BR login (1)
+to restrict the terminals
+on which root is allowed to login.
+See
+.BR login.defs (5)
+if you use the shadow suite.
+.P
+On PAM enabled systems, it is used for the same purpose by
+.BR pam_securetty (8)
+to restrict the terminals on which empty passwords are accepted.
+.SH FILES
+.I /etc/securetty
+.SH SEE ALSO
+.BR login (1),
+.BR login.defs (5),
+.BR pam_securetty (8)
diff --git a/man/man5/services.5 b/man/man5/services.5
new file mode 100644
index 000000000..f46f417a6
--- /dev/null
+++ b/man/man5/services.5
@@ -0,0 +1,199 @@
+.\" This manpage is Copyright (C) 1996 Austin Donnelly <and1000@cam.ac.uk>,
+.\" with additional material Copyright (c) 1995 Martin Schulze
+.\"     <joey@infodrom.north.de>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"   This manpage was made by merging two independently written manpages,
+.\"   one written by Martin Schulze (18 Oct 95), the other written by
+.\"   Austin Donnelly, (9 Jan 96).
+.\"
+.\" Thu Jan 11 12:14:41 1996 Austin Donnelly  <and1000@cam.ac.uk>
+.\"   * Merged two services(5) manpages
+.\"
+.TH services 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+services \- Internet network services list
+.SH DESCRIPTION
+.B services
+is a plain ASCII file providing a mapping between human-friendly textual
+names for internet services, and their underlying assigned port
+numbers and protocol types.
+Every networking program should look into
+this file to get the port number (and protocol) for its service.
+The C library routines
+.BR getservent (3),
+.BR getservbyname (3),
+.BR getservbyport (3),
+.BR setservent (3),
+and
+.BR endservent (3)
+support querying this file from programs.
+.P
+Port numbers are assigned by the IANA (Internet Assigned Numbers
+Authority), and their current policy is to assign both TCP and UDP
+protocols when assigning a port number.
+Therefore, most entries will
+have two entries, even for TCP-only services.
+.P
+Port numbers below 1024 (so-called "low numbered" ports) can be
+bound to only by root (see
+.BR bind (2),
+.BR tcp (7),
+and
+.BR udp (7)).
+This is so clients connecting to low numbered ports can trust
+that the service running on the port is the standard implementation,
+and not a rogue service run by a user of the machine.
+Well-known port numbers specified by the IANA are normally
+located in this root-only space.
+.P
+The presence of an entry for a service in the
+.B services
+file does not necessarily mean that the service is currently running
+on the machine.
+See
+.BR inetd.conf (5)
+for the configuration of Internet services offered.
+Note that not all
+networking services are started by
+.BR inetd (8),
+and so won't appear in
+.BR inetd.conf (5).
+In particular, news (NNTP) and mail (SMTP) servers are often
+initialized from the system boot scripts.
+.P
+The location of the
+.B services
+file is defined by
+.B _PATH_SERVICES
+in
+.IR <netdb.h> "."
+This is usually set to
+.IR /etc/services "."
+.P
+Each line describes one service, and is of the form:
+.IP
+\f2service-name\ \ \ port\f3/\f2protocol\ \ \ \f1[\f2aliases ...\f1]
+.TP
+where:
+.TP
+.I service-name
+is the friendly name the service is known by and looked up under.
+It is case sensitive.
+Often, the client program is named after the
+.IR service-name "."
+.TP
+.I port
+is the port number (in decimal) to use for this service.
+.TP
+.I protocol
+is the type of protocol to be used.
+This field should match an entry
+in the
+.BR protocols (5)
+file.
+Typical values include
+.B tcp
+and
+.BR udp .
+.TP
+.I aliases
+is an optional space or tab separated list of other names for this
+service.
+Again, the names are case
+sensitive.
+.P
+Either spaces or tabs may be used to separate the fields.
+.P
+Comments are started by the hash sign (#) and continue until the end
+of the line.
+Blank lines are skipped.
+.P
+The
+.I service-name
+should begin in the first column of the file, since leading spaces are
+not stripped.
+.I service-names
+can be any printable characters excluding space and tab.
+However, a conservative choice of characters should be used to minimize
+compatibility problems.
+For example, a\-z, 0\-9, and hyphen (\-) would seem a
+sensible choice.
+.P
+Lines not matching this format should not be present in the
+file.
+(Currently, they are silently skipped by
+.BR getservent (3),
+.BR getservbyname (3),
+and
+.BR getservbyport (3).
+However, this behavior should not be relied on.)
+.P
+.\" The following is not true as at glibc 2.8 (a line with a comma is
+.\" ignored by getservent()); it's not clear if/when it was ever true.
+.\"   As a backward compatibility feature, the slash (/) between the
+.\"   .I port
+.\"   number and
+.\"   .I protocol
+.\"   name can in fact be either a slash or a comma (,).
+.\"   Use of the comma in
+.\"   modern installations is deprecated.
+.\"
+This file might be distributed over a network using a network-wide
+naming service like Yellow Pages/NIS or BIND/Hesiod.
+.P
+A sample
+.B services
+file might look like this:
+.P
+.in +4n
+.EX
+netstat         15/tcp
+qotd            17/tcp          quote
+msp             18/tcp          # message send protocol
+msp             18/udp          # message send protocol
+chargen         19/tcp          ttytst source
+chargen         19/udp          ttytst source
+ftp             21/tcp
+# 22 \- unassigned
+telnet          23/tcp
+.EE
+.in
+.SH FILES
+.TP
+.I /etc/services
+The Internet network services list
+.TP
+.I <netdb.h>
+Definition of
+.B _PATH_SERVICES
+.\" .SH BUGS
+.\" It's not clear when/if the following was ever true;
+.\" it isn't true for glibc 2.8:
+.\"    There is a maximum of 35 aliases, due to the way the
+.\"    .BR getservent (3)
+.\"    code is written.
+.\"
+.\" It's not clear when/if the following was ever true;
+.\" it isn't true for glibc 2.8:
+.\"    Lines longer than
+.\"    .B BUFSIZ
+.\"    (currently 1024) characters will be ignored by
+.\"    .BR getservent (3),
+.\"    .BR getservbyname (3),
+.\"    and
+.\"    .BR getservbyport (3).
+.\"    However, this will also cause the next line to be mis-parsed.
+.SH SEE ALSO
+.BR listen (2),
+.BR endservent (3),
+.BR getservbyname (3),
+.BR getservbyport (3),
+.BR getservent (3),
+.BR setservent (3),
+.BR inetd.conf (5),
+.BR protocols (5),
+.BR inetd (8)
+.P
+Assigned Numbers RFC, most recently RFC\ 1700, (AKA STD0002).
diff --git a/man/man5/shells.5 b/man/man5/shells.5
new file mode 100644
index 000000000..2a5d63d7e
--- /dev/null
+++ b/man/man5/shells.5
@@ -0,0 +1,40 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Thu May 20 20:45:48 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:11:07 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Nov 21 10:49:38 1993 by Michael Haardt
+.\" Modified Sun Feb 26 15:09:15 1995 by Rik Faith (faith@cs.unc.edu)
+.TH shells 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+shells \- pathnames of valid login shells
+.SH DESCRIPTION
+.I /etc/shells
+is a text file which contains the full pathnames of valid login shells.
+This file is consulted by
+.BR chsh (1)
+and available to be queried by other programs.
+.P
+Be aware that there are programs which consult this file to
+find out if a user is a normal user;
+for example,
+FTP daemons traditionally
+disallow access to users with shells not included in this file.
+.SH FILES
+.I /etc/shells
+.SH EXAMPLES
+.I /etc/shells
+may contain the following paths:
+.P
+.in +4n
+.EX
+.I /bin/sh
+.I /bin/bash
+.I /bin/csh
+.EE
+.in
+.SH SEE ALSO
+.BR chsh (1),
+.BR getusershell (3),
+.BR pam_shells (8)
diff --git a/man/man5/slabinfo.5 b/man/man5/slabinfo.5
new file mode 100644
index 000000000..c3121fa28
--- /dev/null
+++ b/man/man5/slabinfo.5
@@ -0,0 +1,220 @@
+.\" Copyright (c) 2001 Andreas Dilger (adilger@turbolinux.com)
+.\" and Copyright (c) 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH slabinfo 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+slabinfo \- kernel slab allocator statistics
+.SH SYNOPSIS
+.nf
+.B cat /proc/slabinfo
+.fi
+.SH DESCRIPTION
+Frequently used objects in the Linux kernel
+(buffer heads, inodes, dentries, etc.)
+have their own cache.
+The file
+.I /proc/slabinfo
+gives statistics on these caches.
+The following (edited) output shows an example of the
+contents of this file:
+.P
+.EX
+$ \fBsudo cat /proc/slabinfo\fP
+slabinfo \- version: 2.1
+# name    <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> ...
+sigqueue      100  100  160   25  1 : tunables  0  0  0 : slabdata   4   4  0
+sighand_cache 355   405 2112  15  8 : tunables  0  0  0 : slabdata  27  27  0
+kmalloc\-8192   96   96  8192   4  8 : tunables  0  0  0 : slabdata  24  24  0
+\&...
+.EE
+.P
+The first line of output includes a version number,
+which allows an application that is reading the file to handle changes
+in the file format.
+(See VERSIONS, below.)
+The next line lists the names of the columns in the remaining lines.
+.P
+Each of the remaining lines displays information about a specified cache.
+Following the cache name,
+the output shown in each line shows three components for each cache:
+.IP \[bu] 3
+statistics
+.IP \[bu]
+tunables
+.IP \[bu]
+slabdata
+.P
+The statistics are as follows:
+.TP
+.I active_objs
+The number of objects that are currently active (i.e., in use).
+.TP
+.I num_objs
+The total number of allocated objects
+(i.e., objects that are both in use and not in use).
+.TP
+.I objsize
+The size of objects in this slab, in bytes.
+.TP
+.I objperslab
+The number of objects stored in each slab.
+.TP
+.I pagesperslab
+The number of pages allocated for each slab.
+.P
+The
+.I tunables
+entries in each line show tunable parameters for the corresponding cache.
+When using the default SLUB allocator, there are no tunables, the
+.I /proc/slabinfo
+file is not writable, and the value 0 is shown in these fields.
+When using the older SLAB allocator,
+the tunables for a particular cache can be set by writing
+lines of the following form to
+.IR /proc/slabinfo :
+.P
+.in +4n
+.EX
+# \fBecho \[aq]name limit batchcount sharedfactor\[aq] > /proc/slabinfo\fP
+.EE
+.in
+.P
+Here,
+.I name
+is the cache name, and
+.IR limit ,
+.IR batchcount ,
+and
+.I sharedfactor
+are integers defining new values for the corresponding tunables.
+The
+.I limit
+value should be a positive value,
+.I batchcount
+should be a positive value that is less than or equal to
+.IR limit ,
+and
+.I sharedfactor
+should be nonnegative.
+If any of the specified values is invalid,
+the cache settings are left unchanged.
+.P
+The
+.I tunables
+entries in each line contain the following fields:
+.TP
+.I limit
+The maximum number of objects that will be cached.
+.\" https://lwn.net/Articles/56360/
+.\"     This is the limit on the number of free objects that can be stored
+.\"     in the per-CPU free list for this slab cache.
+.TP
+.I batchcount
+On SMP systems, this specifies the number of objects to transfer at one time
+when refilling the available object list.
+.\" https://lwn.net/Articles/56360/
+.\"     On SMP systems, when we refill the available object list, instead
+.\"     of doing one object at a time, we do batch-count objects at a time.
+.TP
+.I sharedfactor
+[To be documented]
+.\"
+.P
+The
+.I slabdata
+entries in each line contain the following fields:
+.TP
+.I active_slabs
+The number of active slabs.
+.TP
+.I nums_slabs
+The total number of slabs.
+.TP
+.I sharedavail
+[To be documented]
+.P
+Note that because of object alignment and slab cache overhead,
+objects are not normally packed tightly into pages.
+Pages with even one in-use object are considered in-use and cannot be
+freed.
+.P
+Kernels configured with
+.B CONFIG_DEBUG_SLAB
+will also have additional statistics fields in each line,
+and the first line of the file will contain the string "(statistics)".
+The statistics field include : the high water mark of active
+objects; the number of times objects have been allocated;
+the number of times the cache has grown (new pages added
+to this cache); the number of times the cache has been
+reaped (unused pages removed from this cache); and the
+number of times there was an error allocating new pages
+to this cache.
+.\"
+.\" SMP systems will also have "(SMP)" in the first line of
+.\" output, and will have two additional columns for each slab,
+.\" reporting the slab allocation policy for the CPU-local
+.\" cache (to reduce the need for inter-CPU synchronization
+.\" when allocating objects from the cache).
+.\" The first column is the per-CPU limit: the maximum number of objects that
+.\" will be cached for each CPU.
+.\" The second column is the
+.\" batchcount: the maximum number of free objects in the
+.\" global cache that will be transferred to the per-CPU cache
+.\" if it is empty, or the number of objects to be returned
+.\" to the global cache if the per-CPU cache is full.
+.\"
+.\" If both slab cache statistics and SMP are defined, there
+.\" will be four additional columns, reporting the per-CPU
+.\" cache statistics.
+.\" The first two are the per-CPU cache
+.\" allocation hit and miss counts: the number of times an
+.\" object was or was not available in the per-CPU cache
+.\" for allocation.
+.\" The next two are the per-CPU cache free
+.\" hit and miss counts: the number of times a freed object
+.\" could or could not fit within the per-CPU cache limit,
+.\" before flushing objects to the global cache.
+.SH VERSIONS
+The
+.I /proc/slabinfo
+file first appeared in Linux 2.1.23.
+The file is versioned,
+and over time there have been a number of versions with different layouts:
+.TP
+1.0
+Present throughout the Linux 2.2.x kernel series.
+.TP
+1.1
+Present in the Linux 2.4.x kernel series.
+.\" First appeared in Linux 2.4.0-test3
+.TP
+1.2
+A format that was briefly present in the Linux 2.5 development series.
+.\" from Linux 2.5.45 to Linux 2.5.70
+.TP
+2.0
+Present in Linux 2.6.x kernels up to and including Linux 2.6.9.
+.\" First appeared in Linux 2.5.71
+.TP
+2.1
+The current format, which first appeared in Linux 2.6.10.
+.SH NOTES
+Only root can read and (if the kernel was configured with
+.BR CONFIG_SLAB )
+write the
+.I /proc/slabinfo
+file.
+.P
+The total amount of memory allocated to the SLAB/SLUB cache is shown in the
+.I Slab
+field of
+.IR /proc/meminfo .
+.SH SEE ALSO
+.BR slabtop (1)
+.P
+The kernel source file
+.I Documentation/vm/slub.txt
+and
+.IR tools/vm/slabinfo.c .
diff --git a/man/man5/sysfs.5 b/man/man5/sysfs.5
new file mode 100644
index 000000000..b118bb650
--- /dev/null
+++ b/man/man5/sysfs.5
@@ -0,0 +1,275 @@
+.\" Copyright (c) 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sysfs 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysfs \- a filesystem for exporting kernel objects
+.SH DESCRIPTION
+The
+.B sysfs
+filesystem is a pseudo-filesystem which provides an interface to
+kernel data structures.
+(More precisely, the files and directories in
+.B sysfs
+provide a view of the
+.I kobject
+structures defined internally within the kernel.)
+The files under
+.B sysfs
+provide information about devices, kernel modules, filesystems,
+and other kernel components.
+.P
+The
+.B sysfs
+filesystem is commonly mounted at
+.IR /sys .
+Typically, it is mounted automatically by the system,
+but it can also be mounted manually using a command such as:
+.P
+.in +4n
+.EX
+mount \-t sysfs sysfs /sys
+.EE
+.in
+.P
+Many of the files in the
+.B sysfs
+filesystem are read-only,
+but some files are writable, allowing kernel variables to be changed.
+To avoid redundancy,
+symbolic links are heavily used to connect entries across the filesystem tree.
+.\"
+.SS Files and directories
+The following list describes some of the files and directories under the
+.I /sys
+hierarchy.
+.TP
+.I /sys/block
+This subdirectory contains one symbolic link for each block device
+that has been discovered on the system.
+The symbolic links point to corresponding directories under
+.IR /sys/devices .
+.TP
+.I /sys/bus
+This directory contains one subdirectory for each of the bus types
+in the kernel.
+Inside each of these directories are two subdirectories:
+.RS
+.TP
+.I devices
+This subdirectory contains symbolic links to entries in
+.I /sys/devices
+that correspond to the devices discovered on this bus.
+.TP
+.I drivers
+This subdirectory contains one subdirectory for each device driver
+that is loaded on this bus.
+.RE
+.TP
+.I /sys/class
+This subdirectory contains a single layer of further subdirectories
+for each of the device classes that have been registered on the system
+(e.g., terminals, network devices, block devices, graphics devices,
+sound devices, and so on).
+Inside each of these subdirectories are symbolic links for each of the
+devices in this class.
+These symbolic links refer to entries in the
+.I /sys/devices
+directory.
+.TP
+.I /sys/class/net
+Each of the entries in this directory is a symbolic link
+representing one of the real or virtual networking devices
+that are visible in the network namespace of the process
+that is accessing the directory.
+Each of these symbolic links refers to entries in the
+.I /sys/devices
+directory.
+.TP
+.I /sys/dev
+This directory contains two subdirectories
+.I block/
+and
+.IR char/ ,
+corresponding, respectively,
+to the block and character devices on the system.
+Inside each of these subdirectories are symbolic links with names of the form
+.IR major-ID : minor-ID ,
+where the ID values correspond to the major and minor ID of a specific device.
+Each symbolic link points to the
+.B sysfs
+directory for a device.
+The symbolic links inside
+.I /sys/dev
+thus provide an easy way to look up the
+.B sysfs
+interface using the device IDs returned by a call to
+.BR stat (2)
+(or similar).
+.IP
+The following shell session shows an example from
+.IR /sys/dev :
+.IP
+.in +4n
+.EX
+$ \fBstat \-c "%t %T" /dev/null\fP
+1 3
+$ \fBreadlink /sys/dev/char/1\e:3\fP
+\&../../devices/virtual/mem/null
+$ \fBls \-Fd /sys/devices/virtual/mem/null\fP
+/sys/devices/virtual/mem/null/
+$ \fBls \-d1 /sys/devices/virtual/mem/null/*\fP
+/sys/devices/virtual/mem/null/dev
+/sys/devices/virtual/mem/null/power/
+/sys/devices/virtual/mem/null/subsystem@
+/sys/devices/virtual/mem/null/uevent
+.EE
+.in
+.TP
+.I /sys/devices
+This is a directory that contains a filesystem representation of
+the kernel device tree,
+which is a hierarchy of
+.I device
+structures within the kernel.
+.TP
+.I /sys/firmware
+This subdirectory contains interfaces for viewing and manipulating
+firmware-specific objects and attributes.
+.TP
+.I /sys/fs
+This directory contains subdirectories for some filesystems.
+A filesystem will have a subdirectory here only if it chose
+to explicitly create the subdirectory.
+.TP
+.I /sys/fs/cgroup
+This directory conventionally is used as a mount point for a
+.BR tmpfs (5)
+filesystem containing mount points for
+.BR cgroups (7)
+filesystems.
+.TP
+.I /sys/fs/smackfs
+The directory contains configuration files for the SMACK LSM.
+See the kernel source file
+.IR Documentation/admin\-guide/LSM/Smack.rst .
+.TP
+.I /sys/hypervisor
+[To be documented]
+.TP
+.I /sys/kernel
+This subdirectory contains various files and subdirectories that provide
+information about the running kernel.
+.TP
+.I /sys/kernel/cgroup/
+For information about the files in this directory, see
+.BR cgroups (7).
+.TP
+.I /sys/kernel/debug/tracing
+Mount point for the
+.I tracefs
+filesystem used by the kernel's
+.I ftrace
+facility.
+(For information on
+.IR ftrace ,
+see the kernel source file
+.IR Documentation/trace/ftrace.txt .)
+.TP
+.I /sys/kernel/mm
+This subdirectory contains various files and subdirectories that provide
+information about the kernel's memory management subsystem.
+.TP
+.I /sys/kernel/mm/hugepages
+This subdirectory contains one subdirectory for each of the
+huge page sizes that the system supports.
+The subdirectory name indicates the huge page size (e.g.,
+.IR hugepages\-2048kB ).
+Within each of these subdirectories is a set of files
+that can be used to view and (in some cases) change settings
+associated with that huge page size.
+For further information, see the kernel source file
+.IR Documentation/admin\-guide/mm/hugetlbpage.rst .
+.TP
+.I /sys/module
+This subdirectory contains one subdirectory
+for each module that is loaded into the kernel.
+The name of each directory is the name of the module.
+In each of the subdirectories, there may be following files:
+.RS
+.TP
+.I coresize
+[to be documented]
+.TP
+.I initsize
+[to be documented]
+.TP
+.I initstate
+[to be documented]
+.TP
+.I refcnt
+[to be documented]
+.TP
+.I srcversion
+[to be documented]
+.TP
+.I taint
+[to be documented]
+.TP
+.I uevent
+[to be documented]
+.TP
+.I version
+[to be documented]
+.RE
+.IP
+In each of the subdirectories, there may be following subdirectories:
+.RS
+.TP
+.I drivers
+[To be documented]
+.TP
+.I holders
+[To be documented]
+.TP
+.I notes
+[To be documented]
+.TP
+.I parameters
+This directory contains one file for each module parameter,
+with each file containing the value of the corresponding parameter.
+Some of these files are writable, allowing the
+.TP
+.I sections
+This subdirectories contains files with information about module sections.
+This information is mainly used for debugging.
+.TP
+.I
+[To be documented]
+.RE
+.TP
+.I /sys/power
+[To be documented]
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.6.0.
+.SH NOTES
+This manual page is incomplete, possibly inaccurate, and is the kind
+of thing that needs to be updated very often.
+.SH SEE ALSO
+.BR proc (5),
+.BR udev (7)
+.P
+P.\& Mochel. (2005).
+.IR "The sysfs filesystem" .
+Proceedings of the 2005 Ottawa Linux Symposium.
+.\" https://www.kernel.org/pub/linux/kernel/people/mochel/doc/papers/ols-2005/mochel.pdf
+.P
+The kernel source file
+.I Documentation/filesystems/sysfs.txt
+and various other files in
+.I Documentation/ABI
+and
+.I Documentation/*/sysfs.txt
diff --git a/man/man5/termcap.5 b/man/man5/termcap.5
new file mode 100644
index 000000000..3f49c43ac
--- /dev/null
+++ b/man/man5/termcap.5
@@ -0,0 +1,466 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified formatting Sat Jul 24 17:13:38 1993, Rik Faith (faith@cs.unc.edu)
+.\" Modified (extensions and corrections)
+.\"   Sun May  1 14:21:25 MET DST 1994 Michael Haardt
+.\"   If mistakes in the capabilities are found, please send a bug report to:
+.\"   michael@moria.de
+.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond (esr@thyrsus.com)
+.TH termcap 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+termcap \- terminal capability database
+.SH DESCRIPTION
+The termcap database is an obsolete facility for describing the
+capabilities of character-cell terminals and printers.
+It is retained only for compatibility with old programs;
+new programs should use the
+.BR terminfo (5)
+database and associated libraries.
+.P
+.I /etc/termcap
+is an ASCII file (the database master) that lists the capabilities of
+many different types of terminals.
+Programs can read termcap to find
+the particular escape codes needed to control the visual attributes of
+the terminal actually in use.
+(Other aspects of the terminal are
+handled by
+.BR stty (1).)
+The termcap database is indexed on the
+.B TERM
+environment variable.
+.P
+Termcap entries must be defined on a single logical line, with \[aq]\e\[aq]
+used to suppress the newline.
+Fields are separated by \[aq]:\[aq].
+The first field of each entry starts at the left-hand margin,
+and contains a list of names for the terminal, separated by \[aq]|\[aq].
+.P
+The first subfield may (in BSD termcap entries from 4.3BSD and
+earlier) contain a short name consisting of two characters.
+This short name may consist of capital or small letters.
+In 4.4BSD, termcap entries this field is omitted.
+.P
+The second subfield (first, in the newer 4.4BSD format) contains the
+name used by the environment variable
+.BR TERM .
+It should be spelled in lowercase letters.
+Selectable hardware capabilities should be marked
+by appending a hyphen and a suffix to this name.
+See below for an example.
+Usual suffixes are w (more than 80 characters wide), am
+(automatic margins), nam (no automatic margins), and rv (reverse video
+display).
+The third subfield contains a long and descriptive name for
+this termcap entry.
+.P
+Subsequent fields contain the terminal capabilities; any continued
+capability lines must be indented one tab from the left margin.
+.P
+Although there is no defined order, it is suggested to write first
+boolean, then numeric, and then string capabilities, each sorted
+alphabetically without looking at lower or upper spelling.
+Capabilities of similar functions can be written in one line.
+.P
+Example for:
+.nf
+.P
+Head line: vt|vt101|DEC VT 101 terminal in 80 character mode:\e
+Head line: Vt|vt101-w|DEC VT 101 terminal in (wide) 132 character mode:\e
+Boolean: :bs:\e
+Numeric: :co#80:\e
+String: :sr=\eE[H:\e
+.fi
+.SS Boolean capabilities
+.nf
+5i	Printer will not echo on screen
+am	Automatic margins which means automatic line wrap
+bs	Control-H (8 dec.) performs a backspace
+bw	Backspace on left margin wraps to previous line and right margin
+da	Display retained above screen
+db	Display retained below screen
+eo	A space erases all characters at cursor position
+es	Escape sequences and special characters work in status line
+gn	Generic device
+hc	This is a hardcopy terminal
+HC	The cursor is hard to see when not on bottom line
+hs	Has a status line
+hz	Hazeltine bug, the terminal can not print tilde characters
+in	Terminal inserts null bytes, not spaces, to fill whitespace
+km	Terminal has a meta key
+mi	Cursor movement works in insert mode
+ms	Cursor movement works in standout/underline mode
+NP	No pad character
+NR	ti does not reverse te
+nx	No padding, must use XON/XOFF
+os	Terminal can overstrike
+ul	Terminal underlines although it can not overstrike
+xb	Beehive glitch, f1 sends ESCAPE, f2 sends \fB\[ha]C\fP
+xn	Newline/wraparound glitch
+xo	Terminal uses xon/xoff protocol
+xs	Text typed over standout text will be displayed in standout
+xt	Teleray glitch, destructive tabs and odd standout mode
+.fi
+.SS Numeric capabilities
+.nf
+co	Number of columns
+dB	Delay in milliseconds for backspace on hardcopy terminals
+dC	Delay in milliseconds for carriage return on hardcopy terminals
+dF	Delay in milliseconds for form feed on hardcopy terminals
+dN	Delay in milliseconds for new line on hardcopy terminals
+dT	Delay in milliseconds for tabulator stop on hardcopy terminals
+dV	Delay in milliseconds for vertical tabulator stop on
+	hardcopy terminals
+it	Difference between tab positions
+lh	Height of soft labels
+lm	Lines of memory
+lw	Width of soft labels
+li	Number of lines
+Nl	Number of soft labels
+pb	Lowest baud rate which needs padding
+sg	Standout glitch
+ug	Underline glitch
+vt	virtual terminal number
+ws	Width of status line if different from screen width
+.fi
+.SS String capabilities
+.nf
+!1	shifted save key
+!2	shifted suspend key
+!3	shifted undo key
+#1	shifted help key
+#2	shifted home key
+#3	shifted input key
+#4	shifted cursor left key
+%0	redo key
+%1	help key
+%2	mark key
+%3	message key
+%4	move key
+%5	next-object key
+%6	open key
+%7	options key
+%8	previous-object key
+%9	print key
+%a	shifted message key
+%b	shifted move key
+%c	shifted next key
+%d	shifted options key
+%e	shifted previous key
+%f	shifted print key
+%g	shifted redo key
+%h	shifted replace key
+%i	shifted cursor right key
+%j	shifted resume key
+&0	shifted cancel key
+&1	reference key
+&2	refresh key
+&3	replace key
+&4	restart key
+&5	resume key
+&6	save key
+&7	suspend key
+&8	undo key
+&9	shifted begin key
+*0	shifted find key
+*1	shifted command key
+*2	shifted copy key
+*3	shifted create key
+*4	shifted delete character
+*5	shifted delete line
+*6	select key
+*7	shifted end key
+*8	shifted clear line key
+*9	shifted exit key
+@0	find key
+@1	begin key
+@2	cancel key
+@3	close key
+@4	command key
+@5	copy key
+@6	create key
+@7	end key
+@8	enter/send key
+@9	exit key
+al	Insert one line
+AL	Insert %1 lines
+ac	Pairs of block graphic characters to map alternate character set
+ae	End alternative character set
+as	Start alternative character set for block graphic characters
+bc	Backspace, if not \fB\[ha]H\fP
+bl	Audio bell
+bt	Move to previous tab stop
+cb	Clear from beginning of line to cursor
+cc	Dummy command character
+cd	Clear to end of screen
+ce	Clear to end of line
+ch	Move cursor horizontally only to column %1
+cl	Clear screen and cursor home
+cm	Cursor move to row %1 and column %2 (on screen)
+CM	Move cursor to row %1 and column %2 (in memory)
+cr	Carriage return
+cs	Scroll region from line %1 to %2
+ct	Clear tabs
+cv	Move cursor vertically only to line %1
+dc	Delete one character
+DC	Delete %1 characters
+dl	Delete one line
+DL	Delete %1 lines
+dm	Begin delete mode
+do	Cursor down one line
+DO	Cursor down #1 lines
+ds	Disable status line
+eA	Enable alternate character set
+ec	Erase %1 characters starting at cursor
+ed	End delete mode
+ei	End insert mode
+ff	Formfeed character on hardcopy terminals
+fs	Return character to its position before going to status line
+F1	The string sent by function key f11
+F2	The string sent by function key f12
+F3	The string sent by function key f13
+\&...	\&...
+F9	The string sent by function key f19
+FA	The string sent by function key f20
+FB	The string sent by function key f21
+\&...	\&...
+FZ	The string sent by function key f45
+Fa	The string sent by function key f46
+Fb	The string sent by function key f47
+\&...	\&...
+Fr	The string sent by function key f63
+hd	Move cursor a half line down
+ho	Cursor home
+hu	Move cursor a half line up
+i1	Initialization string 1 at login
+i3	Initialization string 3 at login
+is	Initialization string 2 at login
+ic	Insert one character
+IC	Insert %1 characters
+if	Initialization file
+im	Begin insert mode
+ip	Insert pad time and needed special characters after insert
+iP	Initialization program
+K1	upper left key on keypad
+K2	center key on keypad
+K3	upper right key on keypad
+K4	bottom left key on keypad
+K5	bottom right key on keypad
+k0	Function key 0
+k1	Function key 1
+k2	Function key 2
+k3	Function key 3
+k4	Function key 4
+k5	Function key 5
+k6	Function key 6
+k7	Function key 7
+k8	Function key 8
+k9	Function key 9
+k;	Function key 10
+ka	Clear all tabs key
+kA	Insert line key
+kb	Backspace key
+kB	Back tab stop
+kC	Clear screen key
+kd	Cursor down key
+kD	Key for delete character under cursor
+ke	turn keypad off
+kE	Key for clear to end of line
+kF	Key for scrolling forward/down
+kh	Cursor home key
+kH	Cursor hown down key
+kI	Insert character/Insert mode key
+kl	Cursor left key
+kL	Key for delete line
+kM	Key for exit insert mode
+kN	Key for next page
+kP	Key for previous page
+kr	Cursor right key
+kR	Key for scrolling backward/up
+ks	Turn keypad on
+kS	Clear to end of screen key
+kt	Clear this tab key
+kT	Set tab here key
+ku	Cursor up key
+l0	Label of zeroth function key, if not f0
+l1	Label of first function key, if not f1
+l2	Label of first function key, if not f2
+\&...	\&...
+la	Label of tenth function key, if not f10
+le	Cursor left one character
+ll	Move cursor to lower left corner
+LE	Cursor left %1 characters
+LF	Turn soft labels off
+LO	Turn soft labels on
+mb	Start blinking
+MC	Clear soft margins
+md	Start bold mode
+me	End all mode like so, us, mb, md, and mr
+mh	Start half bright mode
+mk	Dark mode (Characters invisible)
+ML	Set left soft margin
+mm	Put terminal in meta mode
+mo	Put terminal out of meta mode
+mp	Turn on protected attribute
+mr	Start reverse mode
+MR	Set right soft margin
+nd	Cursor right one character
+nw	Carriage return command
+pc	Padding character
+pf	Turn printer off
+pk	Program key %1 to send string %2 as if typed by user
+pl	Program key %1 to execute string %2 in local mode
+pn	Program soft label %1 to show string %2
+po	Turn the printer on
+pO	Turn the printer on for %1 (<256) bytes
+ps	Print screen contents on printer
+px	Program key %1 to send string %2 to computer
+r1	Reset string 1 to set terminal to sane modes
+r2	Reset string 2 to set terminal to sane modes
+r3	Reset string 3 to set terminal to sane modes
+RA	disable automatic margins
+rc	Restore saved cursor position
+rf	Reset string filename
+RF	Request for input from terminal
+RI	Cursor right %1 characters
+rp	Repeat character %1 for %2 times
+rP	Padding after character sent in replace mode
+rs	Reset string
+RX	Turn off XON/XOFF flow control
+sa	Set %1 %2 %3 %4 %5 %6 %7 %8 %9 attributes
+SA	enable automatic margins
+sc	Save cursor position
+se	End standout mode
+sf	Normal scroll one line
+SF	Normal scroll %1 lines
+so	Start standout mode
+sr	Reverse scroll
+SR	scroll back %1 lines
+st	Set tabulator stop in all rows at current column
+SX	Turn on XON/XOFF flow control
+ta	move to next hardware tab
+tc	Read in terminal description from another entry
+te	End program that uses cursor motion
+ti	Begin program that uses cursor motion
+ts	Move cursor to column %1 of status line
+uc	Underline character under cursor and move cursor right
+ue	End underlining
+up	Cursor up one line
+UP	Cursor up %1 lines
+us	Start underlining
+vb	Visible bell
+ve	Normal cursor visible
+vi	Cursor invisible
+vs	Standout cursor
+wi	Set window from line %1 to %2 and column %3 to %4
+XF	XOFF character if not \fB\[ha]S\fP
+.fi
+.P
+There are several ways of defining the control codes for string capabilities:
+.P
+Every normal character represents itself,
+except \[aq]\[ha]\[aq], \[aq]\e\[aq], and \[aq]%\[aq].
+.P
+A \fB\[ha]x\fP means Control-x.
+Control-A equals 1 decimal.
+.P
+\ex means a special code.
+x can be one of the following characters:
+.RS
+E Escape (27)
+.br
+n Linefeed (10)
+.br
+r Carriage return (13)
+.br
+t Tabulation (9)
+.br
+b Backspace (8)
+.br
+f Form feed (12)
+.br
+0 Null character.
+A \exxx specifies the octal character xxx.
+.RE
+.TP
+i
+Increments parameters by one.
+.TP
+r
+Single parameter capability
+.TP
++
+Add value of next character to this parameter and do binary output
+.TP
+2
+Do ASCII output of this parameter with a field with of 2
+.TP
+d
+Do ASCII output of this parameter with a field with of 3
+.TP
+%
+Print a \[aq]%\[aq]
+.P
+If you use binary output,
+then you should avoid the null character (\[aq]\e0\[aq])
+because it terminates the string.
+You should reset tabulator expansion
+if a tabulator can be the binary output of a parameter.
+.TP
+Warning:
+The above metacharacters for parameters may be wrong: they document Minix
+termcap which may not be compatible with Linux termcap.
+.P
+The block graphic characters can be specified by three string capabilities:
+.TP
+as
+start the alternative charset
+.TP
+ae
+end the alternative charset
+.TP
+ac
+pairs of characters.
+The first character is the name of the block graphic
+symbol and the second characters is its definition.
+.P
+The following names are available:
+.P
+.nf
++	right arrow (>)
+,	left arrow (<)
+\&.	down arrow (v)
+0	full square (#)
+I	lantern (#)
+-	upper arrow (\[ha])
+\&'	rhombus (+)
+a	chess board (:)
+f	degree (')
+g	plus-minus (#)
+h	square (#)
+j	right bottom corner (+)
+k	right upper corner (+)
+l	left upper corner (+)
+m	left bottom corner (+)
+n	cross (+)
+o	upper horizontal line (-)
+q	middle horizontal line (-)
+s	bottom horizontal line (_)
+t	left tee (+)
+u	right tee (+)
+v	bottom tee (+)
+w	normal tee (+)
+x	vertical line (|)
+\[ti]	paragraph (???)
+.fi
+.P
+The values in parentheses are suggested defaults which are used by the
+.I curses
+library, if the capabilities are missing.
+.SH SEE ALSO
+.BR ncurses (3),
+.BR termcap (3),
+.BR terminfo (5)
diff --git a/man/man5/tmpfs.5 b/man/man5/tmpfs.5
new file mode 100644
index 000000000..69404e135
--- /dev/null
+++ b/man/man5/tmpfs.5
@@ -0,0 +1,281 @@
+.\" Copyright (c) 2016 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH tmpfs 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tmpfs \- a virtual memory filesystem
+.SH DESCRIPTION
+The
+.B tmpfs
+facility allows the creation of filesystems whose contents reside
+in virtual memory.
+Since the files on such filesystems typically reside in RAM,
+file access is extremely fast.
+.P
+The filesystem is automatically created when mounting
+a filesystem with the type
+.B tmpfs
+via a command such as the following:
+.P
+.in +4n
+.EX
+$ sudo mount \-t tmpfs \-o size=10M tmpfs /mnt/mytmpfs
+.EE
+.in
+.P
+A
+.B tmpfs
+filesystem has the following properties:
+.IP \[bu] 3
+The filesystem can employ swap space when physical memory pressure
+demands it.
+.IP \[bu]
+The filesystem consumes only as much physical memory and swap space
+as is required to store the current contents of the filesystem.
+.IP \[bu]
+During a remount operation
+.RI ( "mount\ \-o\ remount" ),
+the filesystem size can be changed
+(without losing the existing contents of the filesystem).
+.P
+If a
+.B tmpfs
+filesystem is unmounted, its contents are discarded (lost).
+.\" See mm/shmem.c:shmem_parse_options for options it supports.
+.SS Mount options
+The
+.B tmpfs
+filesystem supports the following mount options:
+.TP
+.BR size "=\fIbytes\fP"
+Specify an upper limit on the size of the filesystem.
+The size is given in bytes, and rounded up to entire pages.
+The limit is removed if the size is
+.BR 0 .
+.IP
+The size may have a
+.BR k ,
+.BR m ,
+or
+.B g
+suffix for Ki, Mi, Gi (binary kilo (kibi), binary mega (mebi), and binary giga
+(gibi)).
+.IP
+The size may also have a % suffix to limit this instance to a percentage of
+physical RAM.
+.IP
+The default, when neither
+.B size
+nor
+.B nr_blocks
+is specified, is
+.IR size=50% .
+.TP
+.BR nr_blocks "=\fIblocks\fP"
+The same as
+.BR size ,
+but in blocks of
+.BR PAGE_CACHE_SIZE .
+.IP
+Blocks may be specified with
+.BR k ,
+.BR m ,
+or
+.B g
+suffixes like
+.BR size ,
+but not a % suffix.
+.TP
+.BR nr_inodes "=\fIinodes\fP"
+The maximum number of inodes for this instance.
+The default is half of the number of your physical RAM pages, or (on a
+machine with highmem) the number of lowmem RAM pages, whichever is smaller.
+The limit is removed if the number is
+.BR 0 .
+.IP
+Inodes may be specified with
+.BR k ,
+.BR m ,
+or
+.B g
+suffixes like
+.BR size ,
+but not a % suffix.
+.TP
+.BR noswap "(since Linux 6.4)"
+.\" commit 2c6efe9cf2d7841b75fe38ed1adbd41a90f51ba0
+Disables swap.
+Remounts must respect the original settings.
+By default swap is enabled.
+.TP
+.BR mode "=\fImode\fP"
+Set initial permissions of the root directory.
+.TP
+.BR gid "=\fIgid\fP (since Linux 2.5.7)"
+.\" Technically this is also in some version of Linux 2.4.
+.\" commit 099445b489625b80b1d6687c9b6072dbeaca4096
+Set the initial group ID of the root directory.
+.TP
+.BR uid "=\fIuid\fP (since Linux 2.5.7)"
+.\" Technically this is also in some version of Linux 2.4.
+.\" commit 099445b489625b80b1d6687c9b6072dbeaca4096
+Set the initial user ID of the root directory.
+.TP
+.BR huge "=\fIhuge_option\fR (since Linux 4.7.0)"
+.\" commit 5a6e75f8110c97e2a5488894d4e922187e6cb343
+Set the huge table memory allocation policy for all files in this instance (if
+.B CONFIG_TRANSPARENT_HUGEPAGE
+is enabled).
+.IP
+The
+.I huge_option
+value is one of the following:
+.RS
+.TP
+.B never
+Do not allocate huge pages.
+This is the default.
+.TP
+.B always
+Attempt to allocate huge pages every time a new page is needed.
+.TP
+.B within_size
+Only allocate huge page if it will be fully within
+.IR i_size .
+Also respect
+.BR fadvise (2)
+and
+.BR madvise (2)
+hints
+.TP
+.B advise
+Only allocate huge pages if requested with
+.BR fadvise (2)
+or
+.BR madvise (2).
+.TP
+.B deny
+For use in emergencies, to force the huge option off from all mounts.
+.TP
+.B force
+Force the huge option on for all mounts; useful for testing.
+.RE
+.TP
+.BR mpol "=\fImpol_option\fR (since Linux 2.6.15)"
+.\" commit 7339ff8302fd70aabf5f1ae26e0c4905fa74a495
+Set the NUMA memory allocation policy for all files in this instance (if
+.B CONFIG_NUMA
+is enabled).
+.IP
+The
+.I mpol_option
+value is one of the following:
+.RS
+.TP
+.B default
+Use the process allocation policy (see
+.BR set_mempolicy (2)).
+.TP
+.BR prefer ":\fInode\fP"
+Preferably allocate memory from the given
+.IR node .
+.TP
+.BR bind ":\fInodelist\fP"
+Allocate memory only from nodes in
+.IR nodelist .
+.TP
+.B interleave
+Allocate from each node in turn.
+.TP
+.BR interleave ":\fInodelist\fP"
+Allocate from each node of
+.I in
+turn.
+.TP
+.B local
+Preferably allocate memory from the local node.
+.RE
+.IP
+In the above,
+.I nodelist
+is a comma-separated list of decimal numbers and ranges
+that specify NUMA nodes.
+A range is a pair of hyphen-separated decimal numbers,
+the smallest and largest node numbers in the range.
+For example,
+.IR mpol=bind:0\-3,5,7,9\-15 .
+.SH VERSIONS
+The
+.B tmpfs
+facility was added in Linux 2.4, as a successor to the older
+.B ramfs
+facility, which did not provide limit checking or
+allow for the use of swap space.
+.SH NOTES
+In order for user-space tools and applications to create
+.B tmpfs
+filesystems, the kernel must be configured with the
+.B CONFIG_TMPFS
+option.
+.P
+The
+.B tmpfs
+filesystem supports extended attributes (see
+.BR xattr (7)),
+but
+.I user
+extended attributes are not permitted.
+.P
+An internal shared memory filesystem is used for
+System V shared memory
+.RB ( shmget (2))
+and shared anonymous mappings
+.RB ( mmap (2)
+with the
+.B MAP_SHARED
+and
+.B MAP_ANONYMOUS
+flags).
+This filesystem is available regardless of whether
+the kernel was configured with the
+.B CONFIG_TMPFS
+option.
+.P
+A
+.B tmpfs
+filesystem mounted at
+.I /dev/shm
+is used for the implementation of POSIX shared memory
+.RB ( shm_overview (7))
+and POSIX semaphores
+.RB ( sem_overview (7)).
+.P
+The amount of memory consumed by all
+.B tmpfs
+filesystems is shown in the
+.I Shmem
+field of
+.I /proc/meminfo
+and in the
+.I shared
+field displayed by
+.BR free (1).
+.P
+The
+.B tmpfs
+facility was formerly called
+.BR shmfs .
+.SH SEE ALSO
+.BR df (1),
+.BR du (1),
+.BR memfd_create (2),
+.BR mmap (2),
+.BR set_mempolicy (2),
+.BR shm_open (3),
+.BR mount (8)
+.P
+The kernel source files
+.I Documentation/filesystems/tmpfs.txt
+and
+.IR Documentation/admin\-guide/mm/transhuge.rst .
diff --git a/man/man5/ttytype.5 b/man/man5/ttytype.5
new file mode 100644
index 000000000..fd257de97
--- /dev/null
+++ b/man/man5/ttytype.5
@@ -0,0 +1,56 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:17:50 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Thu Oct 19 21:25:21 MET 1995 by Martin Schulze <joey@infodrom.north.de>
+.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond
+.\" <esr@thyrsus.com>xk
+.TH ttytype 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ttytype \- terminal device to default terminal type mapping
+.SH DESCRIPTION
+The
+.I /etc/ttytype
+file associates
+.BR termcap (5)
+and
+.BR terminfo (5)
+terminal type names
+with tty lines.
+Each line consists of a terminal type, followed by
+whitespace, followed by a tty name (a device name without the
+.I /dev/
+prefix).
+.P
+This association is used by the program
+.BR tset (1)
+to set the environment variable
+.B TERM
+to the default terminal name for
+the user's current tty.
+.P
+This facility was designed for a traditional time-sharing environment
+featuring character-cell terminals hardwired to a UNIX minicomputer.
+It is little used on modern workstation and personal UNIX systems.
+.SH FILES
+.TP
+.I /etc/ttytype
+the tty definitions file.
+.SH EXAMPLES
+A typical
+.I /etc/ttytype
+is:
+.P
+.in +4n
+.EX
+con80x25 tty1
+vt320 ttys0
+.EE
+.in
+.SH SEE ALSO
+.BR termcap (5),
+.BR terminfo (5),
+.BR agetty (8),
+.BR mingetty (8)
diff --git a/man/man5/tzfile.5 b/man/man5/tzfile.5
new file mode 100644
index 000000000..4aa3f6c28
--- /dev/null
+++ b/man/man5/tzfile.5
@@ -0,0 +1,508 @@
+.\" This file is in the public domain, so clarified as of
+.\" 1996-06-05 by Arthur David Olson.
+.TH tzfile 5 "" "Time Zone Database"
+.SH NAME
+tzfile \- timezone information
+.SH DESCRIPTION
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+The timezone information files used by
+.BR tzset (3)
+are typically found under a directory with a name like
+.IR /usr/share/zoneinfo .
+These files use the format described in Internet RFC 8536.
+Each file is a sequence of 8-bit bytes.
+In a file, a binary integer is represented by a sequence of one or
+more bytes in network order (bigendian, or high-order byte first),
+with all bits significant,
+a signed binary integer is represented using two's complement,
+and a boolean is represented by a one-byte binary integer that is
+either 0 (false) or 1 (true).
+The format begins with a 44-byte header containing the following fields:
+.RS 2
+.IP \(bu 3
+The magic four-byte ASCII sequence
+.q "TZif"
+identifies the file as a timezone information file.
+.IP \(bu
+A byte identifying the version of the file's format
+(as of 2021, either an ASCII NUL,
+.q "2",
+.q "3",
+or
+.q "4" ).
+.IP \(bu
+Fifteen bytes containing zeros reserved for future use.
+.IP \(bu
+Six four-byte integer values, in the following order:
+.RS
+.TP 2
+.B tzh_ttisutcnt
+The number of UT/local indicators stored in the file.
+(UT is Universal Time.)
+.TP
+.B tzh_ttisstdcnt
+The number of standard/wall indicators stored in the file.
+.TP
+.B tzh_leapcnt
+The number of leap seconds for which data entries are stored in the file.
+.TP
+.B tzh_timecnt
+The number of transition times for which data entries are stored
+in the file.
+.TP
+.B tzh_typecnt
+The number of local time types for which data entries are stored
+in the file (must not be zero).
+.TP
+.B tzh_charcnt
+The number of bytes of time zone abbreviation strings
+stored in the file.
+.RE
+.RE
+.PP
+The above header is followed by the following fields, whose lengths
+depend on the contents of the header:
+.RS 2
+.IP \(bu 3
+.B tzh_timecnt
+four-byte signed integer values sorted in ascending order.
+These values are written in network byte order.
+Each is used as a transition time (as returned by
+.BR time (2))
+at which the rules for computing local time change.
+.IP \(bu
+.B tzh_timecnt
+one-byte unsigned integer values;
+each one but the last tells which of the different types of local time types
+described in the file is associated with the time period
+starting with the same-indexed transition time
+and continuing up to but not including the next transition time.
+(The last time type is present only for consistency checking with the
+POSIX.1-2017-style TZ string described below.)
+These values serve as indices into the next field.
+.IP \(bu
+.B tzh_typecnt
+.B ttinfo
+entries, each defined as follows:
+.in +2
+.sp
+.nf
+.ta \w'\0\0\0\0'u +\w'unsigned char\0'u
+struct ttinfo {
+	int32_t	tt_utoff;
+	unsigned char	tt_isdst;
+	unsigned char	tt_desigidx;
+};
+.in
+.fi
+.sp
+Each structure is written as a four-byte signed integer value for
+.BR tt_utoff ,
+in network byte order, followed by a one-byte boolean for
+.B tt_isdst
+and a one-byte value for
+.BR tt_desigidx .
+In each structure,
+.B tt_utoff
+gives the number of seconds to be added to UT,
+.B tt_isdst
+tells whether
+.B tm_isdst
+should be set by
+.BR localtime (3)
+and
+.B tt_desigidx
+serves as an index into the array of time zone abbreviation bytes
+that follow the
+.B ttinfo
+entries in the file; if the designated string is "\*-00", the
+.B ttinfo
+entry is a placeholder indicating that local time is unspecified.
+The
+.B tt_utoff
+value is never equal to \-2**31, to let 32-bit clients negate it without
+overflow.
+Also, in realistic applications
+.B tt_utoff
+is in the range [\-89999, 93599] (i.e., more than \-25 hours and less
+than 26 hours); this allows easy support by implementations that
+already support the POSIX-required range [\-24:59:59, 25:59:59].
+.IP \(bu
+.B tzh_charcnt
+bytes that represent time zone designations,
+which are null-terminated byte strings, each indexed by the
+.B tt_desigidx
+values mentioned above.
+The byte strings can overlap if one is a suffix of the other.
+The encoding of these strings is not specified.
+.IP \(bu
+.B tzh_leapcnt
+pairs of four-byte values, written in network byte order;
+the first value of each pair gives the nonnegative time
+(as returned by
+.BR time (2))
+at which a leap second occurs or at which the leap second table expires;
+the second is a signed integer specifying the correction, which is the
+.I total
+number of leap seconds to be applied during the time period
+starting at the given time.
+The pairs of values are sorted in strictly ascending order by time.
+Each pair denotes one leap second, either positive or negative,
+except that if the last pair has the same correction as the previous one,
+the last pair denotes the leap second table's expiration time.
+Each leap second is at the end of a UTC calendar month.
+The first leap second has a nonnegative occurrence time,
+and is a positive leap second if and only if its correction is positive;
+the correction for each leap second after the first differs
+from the previous leap second by either 1 for a positive leap second,
+or \-1 for a negative leap second.
+If the leap second table is empty, the leap-second correction is zero
+for all timestamps;
+otherwise, for timestamps before the first occurrence time,
+the leap-second correction is zero if the first pair's correction is 1 or \-1,
+and is unspecified otherwise (which can happen only in files
+truncated at the start).
+.IP \(bu
+.B tzh_ttisstdcnt
+standard/wall indicators, each stored as a one-byte boolean;
+they tell whether the transition times associated with local time types
+were specified as standard time or local (wall clock) time.
+.IP \(bu
+.B tzh_ttisutcnt
+UT/local indicators, each stored as a one-byte boolean;
+they tell whether the transition times associated with local time types
+were specified as UT or local time.
+If a UT/local indicator is set, the corresponding standard/wall indicator
+must also be set.
+.RE
+.PP
+The standard/wall and UT/local indicators were designed for
+transforming a TZif file's transition times into transitions appropriate
+for another time zone specified via
+a POSIX.1-2017-style TZ string that lacks rules.
+For example, when TZ="EET\*-2EEST" and there is no TZif file "EET\*-2EEST",
+the idea was to adapt the transition times from a TZif file with the
+well-known name "posixrules" that is present only for this purpose and
+is a copy of the file "Europe/Brussels", a file with a different UT offset.
+POSIX does not specify this obsolete transformational behavior,
+the default rules are installation-dependent, and no implementation
+is known to support this feature for timestamps past 2037,
+so users desiring (say) Greek time should instead specify
+TZ="Europe/Athens" for better historical coverage, falling back on
+TZ="EET\*-2EEST,M3.5.0/3,M10.5.0/4" if POSIX conformance is required
+and older timestamps need not be handled accurately.
+.PP
+The
+.BR localtime (3)
+function
+normally uses the first
+.B ttinfo
+structure in the file
+if either
+.B tzh_timecnt
+is zero or the time argument is less than the first transition time recorded
+in the file.
+.SS Version 2 format
+For version-2-format timezone files,
+the above header and data are followed by a second header and data,
+identical in format except that
+eight bytes are used for each transition time or leap second time.
+(Leap second counts remain four bytes.)
+After the second header and data comes a newline-enclosed string
+in the style of the contents of a POSIX.1-2017 TZ environment variable,
+for use in handling instants
+after the last transition time stored in the file
+or for all instants if the file has no transitions.
+The TZ string is empty (i.e., nothing between the newlines)
+if there is no POSIX.1-2017-style representation for such instants.
+If nonempty, the TZ string must agree with the local time
+type after the last transition time if present in the eight-byte data;
+for example, given the string
+.q "WET0WEST,M3.5.0/1,M10.5.0"
+then if a last transition time is in July, the transition's local time
+type must specify a daylight-saving time abbreviated
+.q "WEST"
+that is one hour east of UT.
+Also, if there is at least one transition, time type 0 is associated
+with the time period from the indefinite past up to but not including
+the earliest transition time.
+.SS Version 3 format
+For version-3-format timezone files, the TZ string may
+use two minor extensions to the POSIX.1-2017 TZ format, as described in
+.BR newtzset (3).
+First, the hours part of its transition times may be signed and range from
+\-167 through 167 instead of the POSIX-required unsigned values
+from 0 through 24.
+Second, DST is in effect all year if it starts
+January 1 at 00:00 and ends December 31 at 24:00 plus the difference
+between daylight saving and standard time.
+.SS Version 4 format
+For version-4-format TZif files,
+the first leap second record can have a correction that is neither
++1 nor \-1, to represent truncation of the TZif file at the start.
+Also, if two or more leap second transitions are present and the last
+entry's correction equals the previous one, the last entry
+denotes the expiration of the leap second table instead of a leap second;
+timestamps after this expiration are unreliable in that future
+releases will likely add leap second entries after the expiration, and
+the added leap seconds will change how post-expiration timestamps are treated.
+.SS Interoperability considerations
+Future changes to the format may append more data.
+.PP
+Version 1 files are considered a legacy format and
+should not be generated, as they do not support transition
+times after the year 2038.
+Readers that understand only Version 1 must ignore
+any data that extends beyond the calculated end of the version
+1 data block.
+.PP
+Other than version 1, writers should generate
+the lowest version number needed by a file's data.
+For example, a writer should generate a version 4 file
+only if its leap second table either expires or is truncated at the start.
+Likewise, a writer not generating a version 4 file
+should generate a version 3 file only if
+TZ string extensions are necessary to accurately
+model transition times.
+.PP
+The sequence of time changes defined by the version 1
+header and data block should be a contiguous sub-sequence
+of the time changes defined by the version 2+ header and data
+block, and by the footer.
+This guideline helps obsolescent version 1 readers
+agree with current readers about timestamps within the
+contiguous sub-sequence.  It also lets writers not
+supporting obsolescent readers use a
+.B tzh_timecnt
+of zero
+in the version 1 data block to save space.
+.PP
+When a TZif file contains a leap second table expiration
+time, TZif readers should either refuse to process
+post-expiration timestamps, or process them as if the expiration
+time did not exist (possibly with an error indication).
+.PP
+Time zone designations should consist of at least three (3)
+and no more than six (6) ASCII characters from the set of
+alphanumerics,
+.q "\*-",
+and
+.q "+".
+This is for compatibility with POSIX requirements for
+time zone abbreviations.
+.PP
+When reading a version 2 or higher file, readers
+should ignore the version 1 header and data block except for
+the purpose of skipping over them.
+.PP
+Readers should calculate the total lengths of the
+headers and data blocks and check that they all fit within
+the actual file size, as part of a validity check for the file.
+.PP
+When a positive leap second occurs, readers should append an extra
+second to the local minute containing the second just before the leap
+second.  If this occurs when the UTC offset is not a multiple of 60
+seconds, the leap second occurs earlier than the last second of the
+local minute and the minute's remaining local seconds are numbered
+through 60 instead of the usual 59; the UTC offset is unaffected.
+.SS Common interoperability issues
+This section documents common problems in reading or writing TZif files.
+Most of these are problems in generating TZif files for use by
+older readers.
+The goals of this section are:
+.RS 2
+.IP \(bu 3
+to help TZif writers output files that avoid common
+pitfalls in older or buggy TZif readers,
+.IP \(bu
+to help TZif readers avoid common pitfalls when reading
+files generated by future TZif writers, and
+.IP \(bu
+to help any future specification authors see what sort of
+problems arise when the TZif format is changed.
+.RE
+.PP
+When new versions of the TZif format have been defined, a
+design goal has been that a reader can successfully use a TZif
+file even if the file is of a later TZif version than what the
+reader was designed for.
+When complete compatibility was not achieved, an attempt was
+made to limit glitches to rarely used timestamps and allow
+simple partial workarounds in writers designed to generate
+new-version data useful even for older-version readers.
+This section attempts to document these compatibility issues and
+workarounds, as well as to document other common bugs in
+readers.
+.PP
+Interoperability problems with TZif include the following:
+.RS 2
+.IP \(bu 3
+Some readers examine only version 1 data.
+As a partial workaround, a writer can output as much version 1
+data as possible.
+However, a reader should ignore version 1 data, and should use
+version 2+ data even if the reader's native timestamps have only
+32 bits.
+.IP \(bu
+Some readers designed for version 2 might mishandle
+timestamps after a version 3 or higher file's last transition, because
+they cannot parse extensions to POSIX.1-2017 in the TZ-like string.
+As a partial workaround, a writer can output more transitions
+than necessary, so that only far-future timestamps are
+mishandled by version 2 readers.
+.IP \(bu
+Some readers designed for version 2 do not support
+permanent daylight saving time with transitions after 24:00
+\(en e.g., a TZ string
+.q "EST5EDT,0/0,J365/25"
+denoting permanent Eastern Daylight Time
+(\-04).
+As a workaround, a writer can substitute standard time
+for two time zones east, e.g.,
+.q "XXX3EDT4,0/0,J365/23"
+for a time zone with a never-used standard time (XXX, \-03)
+and negative daylight saving time (EDT, \-04) all year.
+Alternatively,
+as a partial workaround a writer can substitute standard time
+for the next time zone east \(en e.g.,
+.q "AST4"
+for permanent
+Atlantic Standard Time (\-04).
+.IP \(bu
+Some readers designed for version 2 or 3, and that require strict
+conformance to RFC 8536, reject version 4 files whose leap second
+tables are truncated at the start or that end in expiration times.
+.IP \(bu
+Some readers ignore the footer, and instead predict future
+timestamps from the time type of the last transition.
+As a partial workaround, a writer can output more transitions
+than necessary.
+.IP \(bu
+Some readers do not use time type 0 for timestamps before
+the first transition, in that they infer a time type using a
+heuristic that does not always select time type 0.
+As a partial workaround, a writer can output a dummy (no-op)
+first transition at an early time.
+.IP \(bu
+Some readers mishandle timestamps before the first
+transition that has a timestamp not less than \-2**31.
+Readers that support only 32-bit timestamps are likely to be
+more prone to this problem, for example, when they process
+64-bit transitions only some of which are representable in 32
+bits.
+As a partial workaround, a writer can output a dummy
+transition at timestamp \-2**31.
+.IP \(bu
+Some readers mishandle a transition if its timestamp has
+the minimum possible signed 64-bit value.
+Timestamps less than \-2**59 are not recommended.
+.IP \(bu
+Some readers mishandle TZ strings that
+contain
+.q "<"
+or
+.q ">".
+As a partial workaround, a writer can avoid using
+.q "<"
+or
+.q ">"
+for time zone abbreviations containing only alphabetic
+characters.
+.IP \(bu
+Many readers mishandle time zone abbreviations that contain
+non-ASCII characters.
+These characters are not recommended.
+.IP \(bu
+Some readers may mishandle time zone abbreviations that
+contain fewer than 3 or more than 6 characters, or that
+contain ASCII characters other than alphanumerics,
+.q "\*-",
+and
+.q "+".
+These abbreviations are not recommended.
+.IP \(bu
+Some readers mishandle TZif files that specify
+daylight-saving time UT offsets that are less than the UT
+offsets for the corresponding standard time.
+These readers do not support locations like Ireland, which
+uses the equivalent of the TZ string
+.q "IST\*-1GMT0,M10.5.0,M3.5.0/1",
+observing standard time
+(IST, +01) in summer and daylight saving time (GMT, +00) in winter.
+As a partial workaround, a writer can output data for the
+equivalent of the TZ string
+.q "GMT0IST,M3.5.0/1,M10.5.0",
+thus swapping standard and daylight saving time.
+Although this workaround misidentifies which part of the year
+uses daylight saving time, it records UT offsets and time zone
+abbreviations correctly.
+.IP \(bu
+Some readers generate ambiguous timestamps for positive leap seconds
+that occur when the UTC offset is not a multiple of 60 seconds.
+For example, in a timezone with UTC offset +01:23:45 and with
+a positive leap second 78796801 (1972-06-30 23:59:60 UTC), some readers will
+map both 78796800 and 78796801 to 01:23:45 local time the next day
+instead of mapping the latter to 01:23:46, and they will map 78796815 to
+01:23:59 instead of to 01:23:60.
+This has not yet been a practical problem, since no civil authority
+has observed such UTC offsets since leap seconds were
+introduced in 1972.
+.RE
+.PP
+Some interoperability problems are reader bugs that
+are listed here mostly as warnings to developers of readers.
+.RS 2
+.IP \(bu 3
+Some readers do not support negative timestamps.
+Developers of distributed applications should keep this
+in mind if they need to deal with pre-1970 data.
+.IP \(bu
+Some readers mishandle timestamps before the first
+transition that has a nonnegative timestamp.
+Readers that do not support negative timestamps are likely to
+be more prone to this problem.
+.IP \(bu
+Some readers mishandle time zone abbreviations like
+.q "\*-08"
+that contain
+.q "+",
+.q "\*-",
+or digits.
+.IP \(bu
+Some readers mishandle UT offsets that are out of the
+traditional range of \-12 through +12 hours, and so do not
+support locations like Kiritimati that are outside this
+range.
+.IP \(bu
+Some readers mishandle UT offsets in the range [\-3599, \-1]
+seconds from UT, because they integer-divide the offset by
+3600 to get 0 and then display the hour part as
+.q "+00".
+.IP \(bu
+Some readers mishandle UT offsets that are not a multiple
+of one hour, or of 15 minutes, or of 1 minute.
+.RE
+.SH SEE ALSO
+.BR time (2),
+.BR localtime (3),
+.BR tzset (3),
+.BR tzselect (8),
+.BR zdump (8),
+.BR zic (8).
+.PP
+Olson A, Eggert P, Murchison K. The Time Zone Information Format (TZif).
+2019 Feb.
+.UR https://\:datatracker.ietf.org/\:doc/\:html/\:rfc8536
+Internet RFC 8536
+.UE
+.UR https://\:doi.org/\:10.17487/\:RFC8536
+doi:10.17487/RFC8536
+.UE .
diff --git a/man/man5/utmp.5 b/man/man5/utmp.5
new file mode 100644
index 000000000..62febabef
--- /dev/null
+++ b/man/man5/utmp.5
@@ -0,0 +1,348 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@cantor.informatik.rwth-aachen.de),
+.\" Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified 1993-07-25 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1995-02-26 by Michael Haardt
+.\" Modified 1996-07-20 by Michael Haardt
+.\" Modified 1997-07-02 by Nicolás Lichtmaier <nick@debian.org>
+.\" Modified 2004-10-31 by aeb, following Gwenole Beauchesne
+.TH utmp 5 (date) "Linux man-pages (unreleased)"
+.SH NAME
+utmp, wtmp \- login records
+.SH SYNOPSIS
+.nf
+.B #include <utmp.h>
+.fi
+.SH DESCRIPTION
+The
+.I utmp
+file allows one to discover information about who is currently using the
+system.
+There may be more users currently using the system, because not
+all programs use utmp logging.
+.P
+.B Warning:
+.I utmp
+must not be writable by the user class "other",
+because many system programs (foolishly)
+depend on its integrity.
+You risk faked system logfiles and
+modifications of system files if you leave
+.I utmp
+writable to any user other than the owner and group owner of the file.
+.P
+The file is a sequence of
+.I utmp
+structures,
+declared as follows in
+.I <utmp.h>
+(note that this is only one of several definitions
+around; details depend on the version of libc):
+.P
+.in +4n
+.EX
+/* Values for ut_type field, below */
+\&
+#define EMPTY         0 /* Record does not contain valid info
+                           (formerly known as UT_UNKNOWN on Linux) */
+#define RUN_LVL       1 /* Change in system run\-level (see
+                           \fBinit\fP(1)) */
+#define BOOT_TIME     2 /* Time of system boot (in \fIut_tv\fP) */
+#define NEW_TIME      3 /* Time after system clock change
+                           (in \fIut_tv\fP) */
+#define OLD_TIME      4 /* Time before system clock change
+                           (in \fIut_tv\fP) */
+#define INIT_PROCESS  5 /* Process spawned by \fBinit\fP(1) */
+#define LOGIN_PROCESS 6 /* Session leader process for user login */
+#define USER_PROCESS  7 /* Normal process */
+#define DEAD_PROCESS  8 /* Terminated process */
+#define ACCOUNTING    9 /* Not implemented */
+\&
+#define UT_LINESIZE      32
+#define UT_NAMESIZE      32
+#define UT_HOSTSIZE     256
+\&
+struct exit_status {              /* Type for ut_exit, below */
+    short e_termination;          /* Process termination status */
+    short e_exit;                 /* Process exit status */
+};
+\&
+struct utmp {
+    short   ut_type;              /* Type of record */
+    pid_t   ut_pid;               /* PID of login process */
+    char    ut_line[UT_LINESIZE]; /* Device name of tty \- "/dev/" */
+    char    ut_id[4];             /* Terminal name suffix,
+                                     or inittab(5) ID */
+    char    ut_user[UT_NAMESIZE]; /* Username */
+    char    ut_host[UT_HOSTSIZE]; /* Hostname for remote login, or
+                                     kernel version for run\-level
+                                     messages */
+    struct  exit_status ut_exit;  /* Exit status of a process
+                                     marked as DEAD_PROCESS; not
+                                     used by Linux init(1) */
+    /* The ut_session and ut_tv fields must be the same size when
+       compiled 32\- and 64\-bit.  This allows data files and shared
+       memory to be shared between 32\- and 64\-bit applications. */
+#if __WORDSIZE == 64 && defined __WORDSIZE_COMPAT32
+    int32_t ut_session;           /* Session ID (\fBgetsid\fP(2)),
+                                     used for windowing */
+    struct {
+        int32_t tv_sec;           /* Seconds */
+        int32_t tv_usec;          /* Microseconds */
+    } ut_tv;                      /* Time entry was made */
+#else
+     long   ut_session;           /* Session ID */
+     struct timeval ut_tv;        /* Time entry was made */
+#endif
+\&
+    int32_t ut_addr_v6[4];        /* Internet address of remote
+                                     host; IPv4 address uses
+                                     just ut_addr_v6[0] */
+    char __unused[20];            /* Reserved for future use */
+};
+\&
+/* Backward compatibility hacks */
+#define ut_name ut_user
+#ifndef _NO_UT_TIME
+#define ut_time ut_tv.tv_sec
+#endif
+#define ut_xtime ut_tv.tv_sec
+#define ut_addr ut_addr_v6[0]
+.EE
+.in
+.P
+This structure gives the name of the special file associated with the
+user's terminal, the user's login name, and the time of login in the form
+of
+.BR time (2).
+String fields are terminated by a null byte (\[aq]\e0\[aq])
+if they are shorter than the size
+of the field.
+.P
+The first entries ever created result from
+.BR init (1)
+processing
+.BR inittab (5).
+Before an entry is processed, though,
+.BR init (1)
+cleans up utmp by setting \fIut_type\fP to \fBDEAD_PROCESS\fP, clearing
+\fIut_user\fP, \fIut_host\fP, and \fIut_time\fP with null bytes for each
+record which \fIut_type\fP is not \fBDEAD_PROCESS\fP or \fBRUN_LVL\fP
+and where no process with PID \fIut_pid\fP exists.
+If no empty record
+with the needed \fIut_id\fP can be found,
+.BR init (1)
+creates a new one.
+It sets \fIut_id\fP from the inittab, \fIut_pid\fP and \fIut_time\fP to the
+current values, and \fIut_type\fP to \fBINIT_PROCESS\fP.
+.P
+.BR mingetty (8)
+(or
+.BR agetty (8))
+locates the entry by the PID, changes \fIut_type\fP to
+\fBLOGIN_PROCESS\fP, changes \fIut_time\fP, sets \fIut_line\fP, and waits
+for connection to be established.
+.BR login (1),
+after a user has been
+authenticated, changes \fIut_type\fP to \fBUSER_PROCESS\fP, changes
+\fIut_time\fP, and sets \fIut_host\fP and \fIut_addr\fP.
+Depending on
+.BR mingetty (8)
+(or
+.BR agetty (8))
+and
+.BR login (1),
+records may be located by
+\fIut_line\fP instead of the preferable \fIut_pid\fP.
+.P
+When
+.BR init (1)
+finds that a process has exited, it locates its utmp entry by
+.IR ut_pid ,
+sets
+.I ut_type
+to
+.BR DEAD_PROCESS ,
+and clears
+.IR ut_user ,
+.IR ut_host ,
+and
+.I ut_time
+with null bytes.
+.P
+.BR xterm (1)
+and other terminal emulators directly create a
+\fBUSER_PROCESS\fP record and generate the \fIut_id\fP by using the
+string that suffix part of the terminal name (the characters
+following
+.IR /dev/ [pt] ty ).
+If they find a \fBDEAD_PROCESS\fP for this ID,
+they recycle it, otherwise they create a new entry.
+If they can, they
+will mark it as \fBDEAD_PROCESS\fP on exiting and it is advised that
+they null \fIut_line\fP, \fIut_time\fP, \fIut_user\fP, and \fIut_host\fP
+as well.
+.P
+.BR telnetd (8)
+sets up a \fBLOGIN_PROCESS\fP entry and leaves the rest to
+.BR login (1)
+as usual.
+After the telnet session ends,
+.BR telnetd (8)
+cleans up utmp in the described way.
+.P
+The \fIwtmp\fP file records all logins and logouts.
+Its format is exactly like \fIutmp\fP except that a null username
+indicates a logout
+on the associated terminal.
+Furthermore, the terminal name \fB\[ti]\fP
+with username \fBshutdown\fP or \fBreboot\fP indicates a system
+shutdown or reboot and the pair of terminal names \fB|\fP/\fB}\fP
+logs the old/new system time when
+.BR date (1)
+changes it.
+\fIwtmp\fP is maintained by
+.BR login (1),
+.BR init (1),
+and some versions of
+.BR getty (8)
+(e.g.,
+.BR mingetty (8)
+or
+.BR agetty (8)).
+None of these programs creates the file, so if it is
+removed, record-keeping is turned off.
+.SH FILES
+.I /var/run/utmp
+.br
+.I /var/log/wtmp
+.SH VERSIONS
+POSIX.1 does not specify a
+.I utmp
+structure, but rather one named
+.I utmpx
+(as part of the XSI extension),
+with specifications for the fields
+.IR ut_type ,
+.IR ut_pid ,
+.IR ut_line ,
+.IR ut_id ,
+.IR ut_user ,
+and
+.IR ut_tv .
+POSIX.1 does not specify the lengths of the
+.I ut_line
+and
+.I ut_user
+fields.
+.P
+Linux defines the
+.I utmpx
+structure to be the same as the
+.I utmp
+structure.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux utmp entries conform neither to v7/BSD nor to System V; they are a
+mix of the two.
+.P
+v7/BSD has fewer fields; most importantly it lacks
+\fIut_type\fP, which causes native v7/BSD-like programs to display (for
+example) dead or login entries.
+Further, there is no configuration file
+which allocates slots to sessions.
+BSD does so because it lacks \fIut_id\fP fields.
+.P
+In Linux (as in System V), the \fIut_id\fP field of a
+record will never change once it has been set, which reserves that slot
+without needing a configuration file.
+Clearing \fIut_id\fP may result
+in race conditions leading to corrupted utmp entries and potential
+security holes.
+Clearing the abovementioned fields by filling them
+with null bytes is not required by System V semantics,
+but makes it possible to run
+many programs which assume BSD semantics and which do not modify utmp.
+Linux uses the BSD conventions for line contents, as documented above.
+.P
+.\" mtk: What is the referrent of "them" in the following sentence?
+.\" System V only uses the type field to mark them and logs
+.\" informative messages such as \fB"new time"\fP in the line field.
+System V has no \fIut_host\fP or \fIut_addr_v6\fP fields.
+.SH NOTES
+Unlike various other
+systems, where utmp logging can be disabled by removing the file, utmp
+must always exist on Linux.
+If you want to disable
+.BR who (1),
+then do not make utmp world readable.
+.P
+The file format is machine-dependent, so it is recommended that it be
+processed only on the machine architecture where it was created.
+.P
+Note that on \fIbiarch\fP platforms, that is, systems which can run both
+32-bit and 64-bit applications (x86-64, ppc64, s390x, etc.),
+\fIut_tv\fP is the same size in 32-bit mode as in 64-bit mode.
+The same goes for \fIut_session\fP and \fIut_time\fP if they are present.
+This allows data files and shared memory to be shared between
+32-bit and 64-bit applications.
+This is achieved by changing the type of
+.I ut_session
+to
+.IR int32_t ,
+and that of
+.I ut_tv
+to a struct with two
+.I int32_t
+fields
+.I tv_sec
+and
+.IR tv_usec .
+Since \fIut_tv\fP may not be the same as \fIstruct timeval\fP,
+then instead of the call:
+.P
+.in +4n
+.EX
+gettimeofday((struct timeval *) &ut.ut_tv, NULL);
+.EE
+.in
+.P
+the following method of setting this field is recommended:
+.P
+.in +4n
+.EX
+struct utmp ut;
+struct timeval tv;
+\&
+gettimeofday(&tv, NULL);
+ut.ut_tv.tv_sec = tv.tv_sec;
+ut.ut_tv.tv_usec = tv.tv_usec;
+.EE
+.in
+.\" .P
+.\" Note that the \fIutmp\fP struct from libc5 has changed in libc6.
+.\" Because of this,
+.\" binaries using the old libc5 struct will corrupt
+.\" .IR /var/run/utmp " and/or " /var/log/wtmp .
+.\" .SH BUGS
+.\" This man page is based on the libc5 one, things may work differently now.
+.SH SEE ALSO
+.BR ac (1),
+.BR date (1),
+.BR init (1),
+.BR last (1),
+.BR login (1),
+.BR logname (1),
+.BR lslogins (1),
+.BR users (1),
+.BR utmpdump (1),
+.BR who (1),
+.BR getutent (3),
+.BR getutmp (3),
+.BR login (3),
+.BR logout (3),
+.BR logwtmp (3),
+.BR updwtmp (3)
diff --git a/man/man5/utmpx.5 b/man/man5/utmpx.5
new file mode 100644
index 000000000..1fa9e5a5d
--- /dev/null
+++ b/man/man5/utmpx.5
@@ -0,0 +1 @@
+.so man5/utmp.5
diff --git a/man/man5/wtmp.5 b/man/man5/wtmp.5
new file mode 100644
index 000000000..1fa9e5a5d
--- /dev/null
+++ b/man/man5/wtmp.5
@@ -0,0 +1 @@
+.so man5/utmp.5
diff --git a/man/man6/intro.6 b/man/man6/intro.6
new file mode 100644
index 000000000..4a3dd1ed9
--- /dev/null
+++ b/man/man6/intro.6
@@ -0,0 +1,17 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"     Fri Apr  2 11:32:09 MET DST 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:19:57 1993 by Rik Faith (faith@cs.unc.edu)
+.TH intro 6 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to games
+.SH DESCRIPTION
+Section 6 of the manual describes the games and funny little programs
+available on the system.
+.SH NOTES
+.SS Authors and copyright conditions
+Look at the header of the manual page source for the author(s) and copyright
+conditions.
+Note that these can be different from page to page!
diff --git a/man/man7/address_families.7 b/man/man7/address_families.7
new file mode 100644
index 000000000..16fed6a2a
--- /dev/null
+++ b/man/man7/address_families.7
@@ -0,0 +1,392 @@
+.\" Copyright (c) 2018 by Eugene Syromyatnikov <evgsyr@gmail.com>,
+.\" and Copyright (c) 2018 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH address_families 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+address_families \- socket address families (domains)
+.SH SYNOPSIS
+.nf
+.BR "#include <sys/types.h>" "          /* See NOTES */"
+.B #include <sys/socket.h>
+.P
+.BI "int socket(int " domain ", int " type ", int " protocol );
+.fi
+.SH DESCRIPTION
+The
+.I domain
+argument of the
+.BR socket (2)
+specifies a communication domain; this selects the protocol
+family which will be used for communication.
+These families are defined in
+.IR <sys/socket.h> .
+The formats currently understood by the Linux kernel include:
+.TP
+.B AF_UNIX
+.TQ
+.B AF_LOCAL
+Local communication.
+For further information, see
+.BR unix (7).
+.TP
+.B AF_INET
+IPv4 Internet protocols.
+For further information, see
+.BR ip (7).
+.TP
+.B AF_AX25
+Amateur radio AX.25 protocol.
+For further information, see
+.BR ax25 (4).
+.\" Part of ax25-tools
+.TP
+.B AF_IPX
+IPX \- Novell protocols.
+.TP
+.B AF_APPLETALK
+AppleTalk
+For further information, see
+.BR ddp (7).
+.TP
+.B AF_NETROM
+AX.25 packet layer protocol.
+For further information, see
+.BR netrom (4),
+.\" Part of ax25-tools package
+.UR https://www.tldp.org/HOWTO/AX25-HOWTO/x61.html
+.I The Packet Radio Protocols and Linux
+.UE
+and the
+.IR AX.25 ", " NET/ROM ", and " "ROSE network programming"
+chapters of the
+.UR https://www.tldp.org/HOWTO/AX25-HOWTO/x2107.html
+.I Linux Amateur Radio AX.25 HOWTO
+.UE .
+.TP
+.B AF_BRIDGE
+Can't be used for creating sockets;
+mostly used for bridge links in
+.BR rtnetlink (7)
+protocol commands.
+.TP
+.B AF_ATMPVC
+Access to raw ATM Permanent Virtual Circuits (PVCs).
+For further information, see the
+.UR https://www.tldp.org/HOWTO/text/ATM-Linux-HOWTO
+.I ATM on Linux HOWTO
+.UE .
+.TP
+.B AF_X25
+ITU-T X.25 / ISO/IEC\~8208 protocol.
+For further information, see
+.BR x25 (7).
+.TP
+.B AF_INET6
+IPv6 Internet protocols.
+For further information, see
+.BR ipv6 (7).
+.TP
+.B AF_ROSE
+RATS (Radio Amateur Telecommunications Society).
+Open Systems environment (ROSE) AX.25 packet layer protocol.
+For further information, see the resources listed for
+.BR AF_NETROM .
+.TP
+.B AF_DECnet
+DECet protocol sockets.
+See
+.I Documentation/networking/decnet.txt
+in the Linux kernel source tree for details.
+.TP
+.B AF_NETBEUI
+Reserved for "802.2LLC project"; never used.
+.TP
+.B AF_SECURITY
+This was a short-lived (between Linux 2.1.30 and 2.1.99pre2) protocol family
+for firewall upcalls.
+.TP
+.B AF_KEY
+Key management protocol, originally developed for usage with IPsec
+(since Linux 2.1.38).
+This has no relation to
+.BR keyctl (2)
+and the in-kernel key storage facility.
+See
+.UR https://tools.ietf.org/html/rfc2367
+RFC 2367
+.I PF_KEY Key Management API, Version 2
+.UE
+for details.
+.TP
+.B AF_NETLINK
+Kernel user interface device.
+For further information, see
+.BR netlink (7).
+.TP
+.B AF_PACKET
+Low-level packet interface.
+For further information, see
+.BR packet (7).
+.\" .TP
+.\" .B AF_ASH
+.\" Asynchronous Serial Host protocol (?)
+.\" Notes from Eugene Syromyatnikov:
+.\" I haven't found any concrete information about this one;
+.\" it never was implemented in Linux, at least, judging by historical
+.\" repos.  There is also this file (and its variations):
+.\" https://github.com/ecki/net-tools/blob/master/lib/ash.c
+.\" ( https://github.com/ecki/net-tools/commits/master/lib/ash.c )
+.\" it mentions "NET-2 distribution" (BSD Net/2?), but, again, I failed
+.\" to find any mentions of "ash" protocol there.
+.\" (for the reference:
+.\" ftp://pdp11.org.ru/pub/unix-archive/Distributions/UCB/Net2/net2.tar.gz )
+.\" Another source that mentions it is
+.\" https://www.silabs.com/documents/public/user-guides/ug101-uart-gateway-protocol-reference.pdf
+.\" https://www.silabs.com/documents/public/user-guides/ug115-ashv3-protocol-reference.pdf
+.\" but I doubt that it's related, as former files use 64-byte addresses and
+.\" "Hamming-encode of hops", and that's barely combines with a protocol
+.\" that is mainly used over serial connection.
+.TP
+.B AF_ECONET
+.\" commit: 349f29d841dbae854bd7367be7c250401f974f47
+Acorn Econet protocol (removed in Linux 3.5).
+See the
+.UR http://www.8bs.com/othrdnld/manuals/econet.shtml
+Econet documentation
+.UE
+for details.
+.TP
+.B AF_ATMSVC
+Access to ATM Switched Virtual Circuits (SVCs)
+See the
+.UR https://www.tldp.org/HOWTO/text/ATM-Linux-HOWTO
+.I ATM on Linux HOWTO
+.UE
+for details.
+.TP
+.B AF_RDS
+.\" commit: 639b321b4d8f4e412bfbb2a4a19bfebc1e68ace4
+Reliable Datagram Sockets (RDS) protocol (since Linux 2.6.30).
+RDS over RDMA has no relation to
+.B AF_SMC
+or
+.BR AF_XDP .
+For further information, see
+.\" rds-tools: https://github.com/oracle/rds-tools/blob/master/rds.7
+.\" rds-tools: https://github.com/oracle/rds-tools/blob/master/rds-rdma.7
+.BR rds (7),
+.BR rds\-rdma (7),
+and
+.I Documentation/networking/rds.txt
+in the Linux kernel source tree.
+.TP
+.B AF_IRDA
+.\" commits: 1ca163afb6fd569b, d64c2a76123f0300
+Socket interface over IrDA
+(moved to staging in Linux 4.14, removed in Linux 4.17).
+.\" irda-utils: https://sourceforge.net/p/irda/code/HEAD/tree/tags/IRDAUTILS_0_9_18/irda-utils/man/irda.7.gz?format=raw
+For further information, see
+.BR irda (7).
+.TP
+.B AF_PPPOX
+Generic PPP transport layer, for setting up L2 tunnels
+(L2TP and PPPoE).
+See
+.I Documentation/networking/l2tp.txt
+in the Linux kernel source tree for details.
+.TP
+.B AF_WANPIPE
+.\" commits: ce0ecd594d78710422599918a608e96dd1ee6024
+Legacy protocol for wide area network (WAN) connectivity
+that was used by Sangoma WAN cards (called "WANPIPE");
+removed in Linux 2.6.21.
+.TP
+.B AF_LLC
+.\" linux-history commit: 34beb106cde7da233d4df35dd3d6cf4fee937caa
+Logical link control (IEEE 802.2 LLC) protocol, upper part
+of data link layer of ISO/OSI networking protocol stack
+(since Linux 2.4);
+has no relation to
+.BR AF_PACKET .
+See chapter
+.I 13.5.3. Logical Link Control
+in
+.I Understanding Linux Kernel Internals
+(O'Reilly Media, 2006)
+and
+.I IEEE Standards for Local Area Networks: Logical Link Control
+(The Institute of Electronics and Electronics Engineers, Inc.,
+New York, New York, 1985)
+for details.
+See also
+.UR https://wiki.linuxfoundation.org/networking/llc
+some historical notes
+.UE
+regarding its development.
+.TP
+.B AF_IB
+.\" commits: 8d36eb01da5d371f..ce117ffac2e93334
+InfiniBand native addressing (since Linux 3.11).
+.TP
+.B AF_MPLS
+.\" commits: 0189197f441602acdca3f97750d392a895b778fd
+Multiprotocol Label Switching (since Linux 4.1);
+mostly used for configuring MPLS routing via
+.BR netlink (7),
+as it doesn't expose ability to create sockets to user space.
+.TP
+.B AF_CAN
+.\" commits: 8dbde28d9711475a..5423dd67bd0108a1
+Controller Area Network automotive bus protocol (since Linux 2.6.25).
+See
+.I Documentation/networking/can.rst
+in the Linux kernel source tree for details.
+.TP
+.B AF_TIPC
+.\" commits: b97bf3fd8f6a16966d4f18983b2c40993ff937d4
+TIPC, "cluster domain sockets" protocol (since Linux 2.6.16).
+See
+.UR http://tipc.io/programming.html
+.I TIPC Programmer's Guide
+.UE
+and the
+.UR http://tipc.io/protocol.html
+protocol description
+.UE
+for details.
+.TP
+.B AF_BLUETOOTH
+.\" commits: 8d36eb01da5d371f..ce117ffac2e93334
+Bluetooth low-level socket protocol (since Linux 3.11).
+See
+.UR https://git.kernel.org\:/pub/scm\:/bluetooth/bluez.git\:/tree/doc/mgmt-api.txt
+.I Bluetooth Management API overview
+.UE
+and
+.UR https://people.csail.mit.edu/albert/bluez-intro/
+.I An Introduction to Bluetooth Programming
+by Albert Huang
+.UE
+for details.
+.TP
+.B AF_IUCV
+.\" commit: eac3731bd04c7131478722a3c148b78774553116
+IUCV (inter-user communication vehicle) z/VM protocol
+for hypervisor-guest interaction (since Linux 2.6.21);
+has no relation to
+.B AF_VSOCK
+and/or
+.B AF_SMC
+See
+.UR https://www.ibm.com\:/support\:/knowledgecenter\:/en/SSB27U_6.4.0\:/com.ibm.zvm.v640.hcpb4\:/iucv.htm
+.I IUCV protocol overview
+.UE
+for details.
+.TP
+.B AF_RXRPC
+.\" commit: 17926a79320afa9b95df6b977b40cca6d8713cea
+.\" http://people.redhat.com/~dhowells/rxrpc/
+.\" https://www.infradead.org/~dhowells/kafs/af_rxrpc_client.html
+.\" http://workshop.openafs.org/afsbpw09/talks/thu_2/kafs.pdf
+.\" http://pages.cs.wisc.edu/~remzi/OSTEP/dist-afs.pdf
+.\" http://web.mit.edu/kolya/afs/rx/rx-spec
+Rx, Andrew File System remote procedure call protocol
+(since Linux 2.6.22).
+See
+.I Documentation/networking/rxrpc.txt
+in the Linux kernel source tree for details.
+.TP
+.B AF_ISDN
+.\" commit: 1b2b03f8e514e4f68e293846ba511a948b80243c
+New "modular ISDN" driver interface protocol (since Linux 2.6.27).
+See the
+.UR http://www.misdn.eu/wiki/Main_Page/
+mISDN wiki
+.UE
+for details.
+.TP
+.B AF_PHONET
+.\" commit: 4b07b3f69a8471cdc142c51461a331226fef248a
+Nokia cellular modem IPC/RPC interface (since Linux 2.6.31).
+See
+.I Documentation/networking/phonet.txt
+in the Linux kernel source tree for details.
+.TP
+.B AF_IEEE802154
+.\" commit: 9ec7671603573ede31207eb5b0b3e1aa211b2854
+IEEE 802.15.4 WPAN (wireless personal area network) raw packet protocol
+(since Linux 2.6.31).
+See
+.I Documentation/networking/ieee802154.txt
+in the Linux kernel source tree for details.
+.TP
+.B AF_CAIF
+.\" commit: 529d6dad5bc69de14cdd24831e2a14264e93daa4
+.\" https://lwn.net/Articles/371017/
+.\" http://read.pudn.com/downloads157/doc/comm/698729/Misc/caif/Com%20CPU%20to%20Appl%20CPU%20Interface%20DESCRIPTION_LZN901%202002_revR1C.pdf
+.\" http://read.pudn.com/downloads157/doc/comm/698729/Misc/caif/Com%20CPU%20to%20Appl%20CPU%20Interface%20PROTOCOL%20SPECIFICATION_LZN901%201708_revR1A.pdf
+Ericsson's Communication CPU to Application CPU interface (CAIF) protocol
+(since Linux 2.6.36).
+See
+.I Documentation/networking/caif/Linux\-CAIF.txt
+in the Linux kernel source tree for details.
+.TP
+.B AF_ALG
+Interface to kernel crypto API (since Linux 2.6.38).
+See
+.I Documentation/crypto/userspace\-if.rst
+in the Linux kernel source tree for details.
+.TP
+.B AF_VSOCK
+.\" commit: d021c344051af91f42c5ba9fdedc176740cbd238
+VMWare VSockets protocol for hypervisor-guest interaction (since Linux 3.9);
+has no relation to
+.B AF_IUCV
+and
+.BR AF_SMC .
+For further information, see
+.BR vsock (7).
+.TP
+.B AF_KCM
+.\" commit: 03c8efc1ffeb6b82a22c1af8dd908af349563314
+KCM (kernel connection multiplexer) interface (since Linux 4.6).
+See
+.I Documentation/networking/kcm.txt
+in the Linux kernel source tree for details.
+.TP
+.B AF_QIPCRTR
+.\" commit: bdabad3e363d825ddf9679dd431cca0b2c30f881
+Qualcomm IPC router interface protocol (since Linux 4.7).
+.TP
+.B AF_SMC
+.\" commit: f3a3e248f3f7cd9a4bed334022704d7e7fc781bf
+SMC-R (shared memory communications over RDMA) protocol (since Linux 4.11),
+and SMC-D (shared memory communications, direct memory access) protocol
+for intra-node z/VM quest interaction (since Linux 4.19);
+has no relation to
+.BR AF_RDS ", " AF_IUCV
+or
+.BR AF_VSOCK .
+See
+.UR https://tools.ietf.org/html/rfc7609
+RFC 7609
+.I IBM's Shared Memory Communications over RDMA (SMC-R) Protocol
+.UE
+for details regarding SMC-R.
+See
+.UR https://www-01.ibm.com\:/software/network\:/commserver\:/SMC-D/index.html
+.I SMC-D Reference Information
+.UE
+for details regarding SMC-D.
+.TP
+.B AF_XDP
+.\" commit: c0c77d8fb787cfe0c3fca689c2a30d1dad4eaba7
+XDP (express data path) interface (since Linux 4.18).
+See
+.I Documentation/networking/af_xdp.rst
+in the Linux kernel source tree for details.
+.SH SEE ALSO
+.BR socket (2),
+.BR socket (7)
diff --git a/man/man7/aio.7 b/man/man7/aio.7
new file mode 100644
index 000000000..513fbbb73
--- /dev/null
+++ b/man/man7/aio.7
@@ -0,0 +1,446 @@
+.\" Copyright (c) 2010 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH AIO 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+aio \- POSIX asynchronous I/O overview
+.SH DESCRIPTION
+The POSIX asynchronous I/O (AIO) interface allows applications
+to initiate one or more I/O operations that are performed
+asynchronously (i.e., in the background).
+The application can elect to be notified of completion of
+the I/O operation in a variety of ways:
+by delivery of a signal, by instantiation of a thread,
+or no notification at all.
+.P
+The POSIX AIO interface consists of the following functions:
+.TP
+.BR aio_read (3)
+Enqueue a read request.
+This is the asynchronous analog of
+.BR read (2).
+.TP
+.BR aio_write (3)
+Enqueue a write request.
+This is the asynchronous analog of
+.BR write (2).
+.TP
+.BR aio_fsync (3)
+Enqueue a sync request for the I/O operations on a file descriptor.
+This is the asynchronous analog of
+.BR fsync (2)
+and
+.BR fdatasync (2).
+.TP
+.BR aio_error (3)
+Obtain the error status of an enqueued I/O request.
+.TP
+.BR aio_return (3)
+Obtain the return status of a completed I/O request.
+.TP
+.BR aio_suspend (3)
+Suspend the caller until one or more of a specified set of
+I/O requests completes.
+.TP
+.BR aio_cancel (3)
+Attempt to cancel outstanding I/O requests on a specified
+file descriptor.
+.TP
+.BR lio_listio (3)
+Enqueue multiple I/O requests using a single function call.
+.P
+The
+.I aiocb
+("asynchronous I/O control block") structure defines
+parameters that control an I/O operation.
+An argument of this type is employed with all of the functions listed above.
+This structure has the following form:
+.P
+.in +4n
+.EX
+#include <aiocb.h>
+\&
+struct aiocb {
+    /* The order of these fields is implementation\-dependent */
+\&
+    int             aio_fildes;     /* File descriptor */
+    off_t           aio_offset;     /* File offset */
+    volatile void  *aio_buf;        /* Location of buffer */
+    size_t          aio_nbytes;     /* Length of transfer */
+    int             aio_reqprio;    /* Request priority */
+    struct sigevent aio_sigevent;   /* Notification method */
+    int             aio_lio_opcode; /* Operation to be performed;
+                                       lio_listio() only */
+\&
+    /* Various implementation\-internal fields not shown */
+};
+\&
+/* Operation codes for \[aq]aio_lio_opcode\[aq]: */
+\&
+enum { LIO_READ, LIO_WRITE, LIO_NOP };
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I aio_fildes
+The file descriptor on which the I/O operation is to be performed.
+.TP
+.I aio_offset
+This is the file offset at which the I/O operation is to be performed.
+.TP
+.I aio_buf
+This is the buffer used to transfer data for a read or write operation.
+.TP
+.I aio_nbytes
+This is the size of the buffer pointed to by
+.IR aio_buf .
+.TP
+.I aio_reqprio
+This field specifies a value that is subtracted
+from the calling thread's real-time priority in order to
+determine the priority for execution of this I/O request (see
+.BR pthread_setschedparam (3)).
+The specified value must be between 0 and the value returned by
+.IR sysconf(_SC_AIO_PRIO_DELTA_MAX) .
+This field is ignored for file synchronization operations.
+.TP
+.I aio_sigevent
+This field is a structure that specifies how the caller is
+to be notified when the asynchronous I/O operation completes.
+Possible values for
+.I aio_sigevent.sigev_notify
+are
+.BR SIGEV_NONE ,
+.BR SIGEV_SIGNAL ,
+and
+.BR SIGEV_THREAD .
+See
+.BR sigevent (3type)
+for further details.
+.TP
+.I aio_lio_opcode
+The type of operation to be performed; used only for
+.BR lio_listio (3).
+.P
+In addition to the standard functions listed above,
+the GNU C library provides the following extension to the POSIX AIO API:
+.TP
+.BR aio_init (3)
+Set parameters for tuning the behavior of the glibc POSIX AIO implementation.
+.SH ERRORS
+.TP
+.B EINVAL
+The
+.I aio_reqprio
+field of the
+.I aiocb
+structure was less than 0,
+or was greater than the limit returned by the call
+.IR sysconf(_SC_AIO_PRIO_DELTA_MAX) .
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+glibc 2.1.
+.SH NOTES
+It is a good idea to zero out the control block buffer before use (see
+.BR memset (3)).
+The control block buffer and the buffer pointed to by
+.I aio_buf
+must not be changed while the I/O operation is in progress.
+These buffers must remain valid until the I/O operation completes.
+.P
+Simultaneous asynchronous read or write operations using the same
+.I aiocb
+structure yield undefined results.
+.P
+The current Linux POSIX AIO implementation is provided in user space by glibc.
+This has a number of limitations, most notably that maintaining multiple
+threads to perform I/O operations is expensive and scales poorly.
+Work has been in progress for some time on a kernel
+state-machine-based implementation of asynchronous I/O
+(see
+.BR io_submit (2),
+.BR io_setup (2),
+.BR io_cancel (2),
+.BR io_destroy (2),
+.BR io_getevents (2)),
+but this implementation hasn't yet matured to the point where
+the POSIX AIO implementation can be completely
+reimplemented using the kernel system calls.
+.\" http://lse.sourceforge.net/io/aio.html
+.\" http://lse.sourceforge.net/io/aionotes.txt
+.\" http://lwn.net/Articles/148755/
+.SH EXAMPLES
+The program below opens each of the files named in its command-line
+arguments and queues a request on the resulting file descriptor using
+.BR aio_read (3).
+The program then loops,
+periodically monitoring each of the I/O operations
+that is still in progress using
+.BR aio_error (3).
+Each of the I/O requests is set up to provide notification by delivery
+of a signal.
+After all I/O requests have completed,
+the program retrieves their status using
+.BR aio_return (3).
+.P
+The
+.B SIGQUIT
+signal (generated by typing control-\e) causes the program to request
+cancelation of each of the outstanding requests using
+.BR aio_cancel (3).
+.P
+Here is an example of what we might see when running this program.
+In this example, the program queues two requests to standard input,
+and these are satisfied by two lines of input containing
+"abc" and "x".
+.P
+.in +4n
+.EX
+$ \fB./a.out /dev/stdin /dev/stdin\fP
+opened /dev/stdin on descriptor 3
+opened /dev/stdin on descriptor 4
+aio_error():
+    for request 0 (descriptor 3): In progress
+    for request 1 (descriptor 4): In progress
+\fBabc\fP
+I/O completion signal received
+aio_error():
+    for request 0 (descriptor 3): I/O succeeded
+    for request 1 (descriptor 4): In progress
+aio_error():
+    for request 1 (descriptor 4): In progress
+\fBx\fP
+I/O completion signal received
+aio_error():
+    for request 1 (descriptor 4): I/O succeeded
+All I/O requests completed
+aio_return():
+    for request 0 (descriptor 3): 4
+    for request 1 (descriptor 4): 2
+.EE
+.in
+.SS Program source
+\&
+.EX
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <aio.h>
+#include <signal.h>
+\&
+#define BUF_SIZE 20     /* Size of buffers for read operations */
+\&
+#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+struct ioRequest {      /* Application\-defined structure for tracking
+                           I/O requests */
+    int           reqNum;
+    int           status;
+    struct aiocb *aiocbp;
+};
+\&
+static volatile sig_atomic_t gotSIGQUIT = 0;
+                        /* On delivery of SIGQUIT, we attempt to
+                           cancel all outstanding I/O requests */
+\&
+static void             /* Handler for SIGQUIT */
+quitHandler(int sig)
+{
+    gotSIGQUIT = 1;
+}
+\&
+#define IO_SIGNAL SIGUSR1   /* Signal used to notify I/O completion */
+\&
+static void                 /* Handler for I/O completion signal */
+aioSigHandler(int sig, siginfo_t *si, void *ucontext)
+{
+    if (si\->si_code == SI_ASYNCIO) {
+        write(STDOUT_FILENO, "I/O completion signal received\en", 31);
+\&
+        /* The corresponding ioRequest structure would be available as
+               struct ioRequest *ioReq = si\->si_value.sival_ptr;
+           and the file descriptor would then be available via
+               ioReq\->aiocbp\->aio_fildes */
+    }
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    struct sigaction sa;
+    int s;
+    int numReqs;        /* Total number of queued I/O requests */
+    int openReqs;       /* Number of I/O requests still in progress */
+\&
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <pathname> <pathname>...\en",
+                argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    numReqs = argc \- 1;
+\&
+    /* Allocate our arrays. */
+\&
+    struct ioRequest *ioList = calloc(numReqs, sizeof(*ioList));
+    if (ioList == NULL)
+        errExit("calloc");
+\&
+    struct aiocb *aiocbList = calloc(numReqs, sizeof(*aiocbList));
+    if (aiocbList == NULL)
+        errExit("calloc");
+\&
+    /* Establish handlers for SIGQUIT and the I/O completion signal. */
+\&
+    sa.sa_flags = SA_RESTART;
+    sigemptyset(&sa.sa_mask);
+\&
+    sa.sa_handler = quitHandler;
+    if (sigaction(SIGQUIT, &sa, NULL) == \-1)
+        errExit("sigaction");
+\&
+    sa.sa_flags = SA_RESTART | SA_SIGINFO;
+    sa.sa_sigaction = aioSigHandler;
+    if (sigaction(IO_SIGNAL, &sa, NULL) == \-1)
+        errExit("sigaction");
+\&
+    /* Open each file specified on the command line, and queue
+       a read request on the resulting file descriptor. */
+\&
+    for (size_t j = 0; j < numReqs; j++) {
+        ioList[j].reqNum = j;
+        ioList[j].status = EINPROGRESS;
+        ioList[j].aiocbp = &aiocbList[j];
+\&
+        ioList[j].aiocbp\->aio_fildes = open(argv[j + 1], O_RDONLY);
+        if (ioList[j].aiocbp\->aio_fildes == \-1)
+            errExit("open");
+        printf("opened %s on descriptor %d\en", argv[j + 1],
+                ioList[j].aiocbp\->aio_fildes);
+\&
+        ioList[j].aiocbp\->aio_buf = malloc(BUF_SIZE);
+        if (ioList[j].aiocbp\->aio_buf == NULL)
+            errExit("malloc");
+\&
+        ioList[j].aiocbp\->aio_nbytes = BUF_SIZE;
+        ioList[j].aiocbp\->aio_reqprio = 0;
+        ioList[j].aiocbp\->aio_offset = 0;
+        ioList[j].aiocbp\->aio_sigevent.sigev_notify = SIGEV_SIGNAL;
+        ioList[j].aiocbp\->aio_sigevent.sigev_signo = IO_SIGNAL;
+        ioList[j].aiocbp\->aio_sigevent.sigev_value.sival_ptr =
+                                &ioList[j];
+\&
+        s = aio_read(ioList[j].aiocbp);
+        if (s == \-1)
+            errExit("aio_read");
+    }
+\&
+    openReqs = numReqs;
+\&
+    /* Loop, monitoring status of I/O requests. */
+\&
+    while (openReqs > 0) {
+        sleep(3);       /* Delay between each monitoring step */
+\&
+        if (gotSIGQUIT) {
+\&
+            /* On receipt of SIGQUIT, attempt to cancel each of the
+               outstanding I/O requests, and display status returned
+               from the cancelation requests. */
+\&
+            printf("got SIGQUIT; canceling I/O requests: \en");
+\&
+            for (size_t j = 0; j < numReqs; j++) {
+                if (ioList[j].status == EINPROGRESS) {
+                    printf("    Request %zu on descriptor %d:", j,
+                            ioList[j].aiocbp\->aio_fildes);
+                    s = aio_cancel(ioList[j].aiocbp\->aio_fildes,
+                            ioList[j].aiocbp);
+                    if (s == AIO_CANCELED)
+                        printf("I/O canceled\en");
+                    else if (s == AIO_NOTCANCELED)
+                        printf("I/O not canceled\en");
+                    else if (s == AIO_ALLDONE)
+                        printf("I/O all done\en");
+                    else
+                        perror("aio_cancel");
+                }
+            }
+\&
+            gotSIGQUIT = 0;
+        }
+\&
+        /* Check the status of each I/O request that is still
+           in progress. */
+\&
+        printf("aio_error():\en");
+        for (size_t j = 0; j < numReqs; j++) {
+            if (ioList[j].status == EINPROGRESS) {
+                printf("    for request %zu (descriptor %d): ",
+                        j, ioList[j].aiocbp\->aio_fildes);
+                ioList[j].status = aio_error(ioList[j].aiocbp);
+\&
+                switch (ioList[j].status) {
+                case 0:
+                    printf("I/O succeeded\en");
+                    break;
+                case EINPROGRESS:
+                    printf("In progress\en");
+                    break;
+                case ECANCELED:
+                    printf("Canceled\en");
+                    break;
+                default:
+                    perror("aio_error");
+                    break;
+                }
+\&
+                if (ioList[j].status != EINPROGRESS)
+                    openReqs\-\-;
+            }
+        }
+    }
+\&
+    printf("All I/O requests completed\en");
+\&
+    /* Check status return of all I/O requests. */
+\&
+    printf("aio_return():\en");
+    for (size_t j = 0; j < numReqs; j++) {
+        ssize_t s;
+\&
+        s = aio_return(ioList[j].aiocbp);
+        printf("    for request %zu (descriptor %d): %zd\en",
+                j, ioList[j].aiocbp\->aio_fildes, s);
+    }
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.ad l
+.nh
+.BR io_cancel (2),
+.BR io_destroy (2),
+.BR io_getevents (2),
+.BR io_setup (2),
+.BR io_submit (2),
+.BR aio_cancel (3),
+.BR aio_error (3),
+.BR aio_init (3),
+.BR aio_read (3),
+.BR aio_return (3),
+.BR aio_write (3),
+.BR lio_listio (3)
+.P
+"Asynchronous I/O Support in Linux 2.5",
+Bhattacharya, Pratt, Pulavarty, and Morgan,
+Proceedings of the Linux Symposium, 2003,
+.UR https://www.kernel.org/doc/ols/2003/ols2003\-pages\-351\-366.pdf
+.UE
diff --git a/man/man7/armscii-8.7 b/man/man7/armscii-8.7
new file mode 100644
index 000000000..0f86c2914
--- /dev/null
+++ b/man/man7/armscii-8.7
@@ -0,0 +1,120 @@
+'\" t
+.\" Copyright 2009  Lefteris Dimitroulakis <edimitro at tee.gr>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ARMSCII-8 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+armscii-8 \- Armenian character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The Armenian Standard Code for Information Interchange,
+8-bit coded character set.
+.SS ArmSCII-8 characters
+The following table displays the characters in ArmSCII-8 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+242	162	A2	և	ARMENIAN SMALL LIGATURE ECH YIWN
+243	163	A3	։	ARMENIAN FULL STOP
+244	164	A4	)	RIGHT PARENTHESIS
+245	165	A5	(	LEFT PARENTHESIS
+246	166	A6	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+247	167	A7	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+250	168	A8	—	EM DASH
+251	169	A9	.	FULL STOP
+252	170	AA	՝	ARMENIAN COMMA
+253	171	AB	,	COMMA
+254	172	AC	-	HYPHEN-MINUS
+255	173	AD	֊	ARMENIAN HYPHEN
+256	174	AE	…	HORIZONTAL ELLIPSIS
+257	175	AF	՜	ARMENIAN EXCLAMATION MARK
+260	176	B0	՛	ARMENIAN EMPHASIS MARK
+261	177	B1	՞	ARMENIAN QUESTION MARK
+262	178	B2	Ա	ARMENIAN CAPITAL LETTER AYB
+263	179	B3	ա	ARMENIAN SMALL LETTER AYB
+264	180	B4	Բ	ARMENIAN CAPITAL LETTER BEN
+265	181	B5	բ	ARMENIAN SMALL LETTER BEN
+266	182	B6	Գ	ARMENIAN CAPITAL LETTER GIM
+267	183	B7	գ	ARMENIAN SMALL LETTER GIM
+270	184	B8	Դ	ARMENIAN CAPITAL LETTER DA
+271	185	B9	դ	ARMENIAN SMALL LETTER DA
+272	186	BA	Ե	ARMENIAN CAPITAL LETTER ECH
+273	187	BB	ե	ARMENIAN SMALL LETTER ECH
+274	188	BC	Զ	ARMENIAN CAPITAL LETTER ZA
+275	189	BD	զ	ARMENIAN SMALL LETTER ZA
+276	190	BE	Է	ARMENIAN CAPITAL LETTER EH
+277	191	BF	է	ARMENIAN SMALL LETTER EH
+300	192	C0	Ը	ARMENIAN CAPITAL LETTER ET
+301	193	C1	ը	ARMENIAN SMALL LETTER ET
+302	194	C2	Թ	ARMENIAN CAPITAL LETTER TO
+303	195	C3	թ	ARMENIAN SMALL LETTER TO
+304	196	C4	Ժ	ARMENIAN CAPITAL LETTER ZHE
+305	197	C5	ժ	ARMENIAN SMALL LETTER ZHE
+306	198	C6	Ի	ARMENIAN CAPITAL LETTER INI
+307	199	C7	ի	ARMENIAN SMALL LETTER INI
+310	200	C8	Լ	ARMENIAN CAPITAL LETTER LIWN
+311	201	C9	լ	ARMENIAN SMALL LETTER LIWN
+312	202	CA	Խ	ARMENIAN CAPITAL LETTER XEH
+313	203	CB	խ	ARMENIAN SMALL LETTER XEH
+314	204	CC	Ծ	ARMENIAN CAPITAL LETTER CA
+315	205	CD	ծ	ARMENIAN SMALL LETTER CA
+316	206	CE	Կ	ARMENIAN CAPITAL LETTER KEN
+317	207	CF	կ	ARMENIAN SMALL LETTER KEN
+320	208	D0	Հ	ARMENIAN CAPITAL LETTER HO
+321	209	D1	հ	ARMENIAN SMALL LETTER HO
+322	210	D2	Ձ	ARMENIAN CAPITAL LETTER JA
+323	211	D3	ձ	ARMENIAN SMALL LETTER JA
+324	212	D4	Ղ	ARMENIAN CAPITAL LETTER GHAD
+325	213	D5	ղ	ARMENIAN SMALL LETTER GHAD
+326	214	D6	Ճ	ARMENIAN CAPITAL LETTER CHEH
+327	215	D7	ճ	ARMENIAN SMALL LETTER CHEH
+330	216	D8	Մ	ARMENIAN CAPITAL LETTER MEN
+331	217	D9	մ	ARMENIAN SMALL LETTER MEN
+332	218	DA	Յ	ARMENIAN CAPITAL LETTER YI
+333	219	DB	յ	ARMENIAN SMALL LETTER YI
+334	220	DC	Ն	ARMENIAN CAPITAL LETTER NOW
+335	221	DD	ն	ARMENIAN SMALL LETTER NOW
+336	222	DE	Շ	ARMENIAN CAPITAL LETTER SHA
+337	223	DF	շ	ARMENIAN SMALL LETTER SHA
+340	224	E0	Ո	ARMENIAN CAPITAL LETTER VO
+341	225	E1	ո	ARMENIAN SMALL LETTER VO
+342	226	E2	Չ	ARMENIAN CAPITAL LETTER CHA
+343	227	E3	չ	ARMENIAN SMALL LETTER CHA
+344	228	E4	Պ	ARMENIAN CAPITAL LETTER PEH
+345	229	E5	պ	ARMENIAN SMALL LETTER PEH
+346	230	E6	Ջ	ARMENIAN CAPITAL LETTER JHEH
+347	231	E7	ջ	ARMENIAN SMALL LETTER JHEH
+350	232	E8	Ռ	ARMENIAN CAPITAL LETTER RA
+351	233	E9	ռ	ARMENIAN SMALL LETTER RA
+352	234	EA	Ս	ARMENIAN CAPITAL LETTER SEH
+353	235	EB	ս	ARMENIAN SMALL LETTER SEH
+354	236	EC	Վ	ARMENIAN CAPITAL LETTER VEW
+355	237	ED	վ	ARMENIAN SMALL LETTER VEW
+356	238	EE	Տ	ARMENIAN CAPITAL LETTER TIWN
+357	239	EF	տ	ARMENIAN SMALL LETTER TIWN
+360	240	F0	Ր	ARMENIAN CAPITAL LETTER REH
+361	241	F1	ր	ARMENIAN SMALL LETTER REH
+362	242	F2	Ց	ARMENIAN CAPITAL LETTER CO
+363	243	F3	ց	ARMENIAN SMALL LETTER CO
+364	244	F4	Ւ	ARMENIAN CAPITAL LETTER YIWN
+365	245	F5	ւ	ARMENIAN SMALL LETTER YIWN
+366	246	F6	Փ	ARMENIAN CAPITAL LETTER PIWR
+367	247	F7	փ	ARMENIAN SMALL LETTER PIWR
+370	248	F8	Ք	ARMENIAN CAPITAL LETTER KEH
+371	249	F9	ք	ARMENIAN SMALL LETTER KEH
+372	250	FA	Օ	ARMENIAN CAPITAL LETTER OH
+373	251	FB	օ	ARMENIAN SMALL LETTER OH
+374	252	FC	Ֆ	ARMENIAN CAPITAL LETTER FEH
+375	253	FD	ֆ	ARMENIAN SMALL LETTER FEH
+376	254	FE	՚	ARMENIAN APOSTROPHE
+.TE
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/arp.7 b/man/man7/arp.7
new file mode 100644
index 000000000..773005b61
--- /dev/null
+++ b/man/man7/arp.7
@@ -0,0 +1,306 @@
+'\" t
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Matthew Wilcox <willy@bofh.ai>.
+.\"
+.\" Modified June 1999 Andi Kleen
+.\" $Id: arp.7,v 1.10 2000/04/27 19:31:38 ak Exp $
+.\"
+.TH arp 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+arp \- Linux ARP kernel module.
+.SH DESCRIPTION
+This kernel protocol module implements the Address Resolution
+Protocol defined in RFC\ 826.
+It is used to convert between Layer2 hardware addresses
+and IPv4 protocol addresses on directly connected networks.
+The user normally doesn't interact directly with this module except to
+configure it;
+instead it provides a service for other protocols in the kernel.
+.P
+A user process can receive ARP packets by using
+.BR packet (7)
+sockets.
+There is also a mechanism for managing the ARP cache
+in user-space by using
+.BR netlink (7)
+sockets.
+The ARP table can also be controlled via
+.BR ioctl (2)
+on any
+.B AF_INET
+socket.
+.P
+The ARP module maintains a cache of mappings between hardware addresses
+and protocol addresses.
+The cache has a limited size so old and less
+frequently used entries are garbage-collected.
+Entries which are marked
+as permanent are never deleted by the garbage-collector.
+The cache can
+be directly manipulated by the use of ioctls and its behavior can be
+tuned by the
+.I /proc
+interfaces described below.
+.P
+When there is no positive feedback for an existing mapping after some
+time (see the
+.I /proc
+interfaces below), a neighbor cache entry is considered stale.
+Positive feedback can be gotten from a higher layer; for example from
+a successful TCP ACK.
+Other protocols can signal forward progress
+using the
+.B MSG_CONFIRM
+flag to
+.BR sendmsg (2).
+When there is no forward progress, ARP tries to reprobe.
+It first tries to ask a local arp daemon
+.B app_solicit
+times for an updated MAC address.
+If that fails and an old MAC address is known, a unicast probe is sent
+.B ucast_solicit
+times.
+If that fails too, it will broadcast a new ARP
+request to the network.
+Requests are sent only when there is data queued
+for sending.
+.P
+Linux will automatically add a nonpermanent proxy arp entry when it
+receives a request for an address it forwards to and proxy arp is
+enabled on the receiving interface.
+When there is a reject route for the target, no proxy arp entry is added.
+.SS Ioctls
+Three ioctls are available on all
+.B AF_INET
+sockets.
+They take a pointer to a
+.I struct arpreq
+as their argument.
+.P
+.in +4n
+.EX
+struct arpreq {
+    struct sockaddr arp_pa;      /* protocol address */
+    struct sockaddr arp_ha;      /* hardware address */
+    int             arp_flags;   /* flags */
+    struct sockaddr arp_netmask; /* netmask of protocol address */
+    char            arp_dev[16];
+};
+.EE
+.in
+.P
+.BR SIOCSARP ", " SIOCDARP " and " SIOCGARP
+respectively set, delete, and get an ARP mapping.
+Setting and deleting ARP maps are privileged operations and may
+be performed only by a process with the
+.B CAP_NET_ADMIN
+capability or an effective UID of 0.
+.P
+.I arp_pa
+must be an
+.B AF_INET
+address and
+.I arp_ha
+must have the same type as the device which is specified in
+.IR arp_dev .
+.I arp_dev
+is a zero-terminated string which names a device.
+.RS
+.TS
+tab(:) allbox;
+c s
+l l.
+\fIarp_flags\fR
+flag:meaning
+ATF_COM:Lookup complete
+ATF_PERM:Permanent entry
+ATF_PUBL:Publish entry
+ATF_USETRAILERS:Trailers requested
+ATF_NETMASK:Use a netmask
+ATF_DONTPUB:Don't answer
+.TE
+.RE
+.P
+If the
+.B ATF_NETMASK
+flag is set, then
+.I arp_netmask
+should be valid.
+Linux 2.2 does not support proxy network ARP entries, so this
+should be set to 0xffffffff, or 0 to remove an existing proxy arp entry.
+.B ATF_USETRAILERS
+is obsolete and should not be used.
+.SS /proc interfaces
+ARP supports a range of
+.I /proc
+interfaces to configure parameters on a global or per-interface basis.
+The interfaces can be accessed by reading or writing the
+.I /proc/sys/net/ipv4/neigh/*/*
+files.
+Each interface in the system has its own directory in
+.IR /proc/sys/net/ipv4/neigh/ .
+The setting in the "default" directory is used for all newly created
+devices.
+Unless otherwise specified, time-related interfaces are specified
+in seconds.
+.TP
+.IR anycast_delay " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The maximum number of jiffies to delay before replying to a
+IPv6 neighbor solicitation message.
+Anycast support is not yet implemented.
+Defaults to 1 second.
+.TP
+.IR app_solicit " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The maximum number of probes to send to the user space ARP daemon via
+netlink before dropping back to multicast probes (see
+.IR mcast_solicit ).
+Defaults to 0.
+.TP
+.IR base_reachable_time " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+Once a neighbor has been found, the entry is considered to be valid
+for at least a random value between
+.IR base_reachable_time "/2 and 3*" base_reachable_time /2.
+An entry's validity will be extended if it receives positive feedback
+from higher level protocols.
+Defaults to 30 seconds.
+This file is now obsolete in favor of
+.IR base_reachable_time_ms .
+.TP
+.IR base_reachable_time_ms " (since Linux 2.6.12)"
+As for
+.IR base_reachable_time ,
+but measures time in milliseconds.
+Defaults to 30000 milliseconds.
+.TP
+.IR delay_first_probe_time " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+Delay before first probe after it has been decided that a neighbor
+is stale.
+Defaults to 5 seconds.
+.TP
+.IR gc_interval " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+How frequently the garbage collector for neighbor entries
+should attempt to run.
+Defaults to 30 seconds.
+.TP
+.IR gc_stale_time " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+Determines how often to check for stale neighbor entries.
+When a neighbor entry is considered stale, it is resolved again before
+sending data to it.
+Defaults to 60 seconds.
+.TP
+.IR gc_thresh1 " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The minimum number of entries to keep in the ARP cache.
+The garbage collector will not run if there are fewer than
+this number of entries in the cache.
+Defaults to 128.
+.TP
+.IR gc_thresh2 " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The soft maximum number of entries to keep in the ARP cache.
+The garbage collector will allow the number of entries to exceed
+this for 5 seconds before collection will be performed.
+Defaults to 512.
+.TP
+.IR gc_thresh3 " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The hard maximum number of entries to keep in the ARP cache.
+The garbage collector will always run if there are more than
+this number of entries in the cache.
+Defaults to 1024.
+.TP
+.IR locktime " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The minimum number of jiffies to keep an ARP entry in the cache.
+This prevents ARP cache thrashing if there is more than one potential
+mapping (generally due to network misconfiguration).
+Defaults to 1 second.
+.TP
+.IR mcast_solicit " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The maximum number of attempts to resolve an address by
+multicast/broadcast before marking the entry as unreachable.
+Defaults to 3.
+.TP
+.IR proxy_delay " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+When an ARP request for a known proxy-ARP address is received, delay up to
+.I proxy_delay
+jiffies before replying.
+This is used to prevent network flooding in some cases.
+Defaults to 0.8 seconds.
+.TP
+.IR proxy_qlen " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The maximum number of packets which may be queued to proxy-ARP addresses.
+Defaults to 64.
+.TP
+.IR retrans_time " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The number of jiffies to delay before retransmitting a request.
+Defaults to 1 second.
+This file is now obsolete in favor of
+.IR retrans_time_ms .
+.TP
+.IR retrans_time_ms " (since Linux 2.6.12)"
+The number of milliseconds to delay before retransmitting a request.
+Defaults to 1000 milliseconds.
+.TP
+.IR ucast_solicit " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The maximum number of attempts to send unicast probes before asking
+the ARP daemon (see
+.IR app_solicit ).
+Defaults to 3.
+.TP
+.IR unres_qlen " (since Linux 2.2)"
+.\" Precisely: 2.1.79
+The maximum number of packets which may be queued for each unresolved
+address by other network layers.
+Defaults to 3.
+.SH VERSIONS
+The
+.I struct arpreq
+changed in Linux 2.0 to include the
+.I arp_dev
+member and the ioctl numbers changed at the same time.
+Support for the old ioctls was dropped in Linux 2.2.
+.P
+Support for proxy arp entries for networks (netmask not equal 0xffffffff)
+was dropped in Linux 2.2.
+It is replaced by automatic proxy arp setup by
+the kernel for all reachable hosts on other interfaces (when
+forwarding and proxy arp is enabled for the interface).
+.P
+The
+.I neigh/*
+interfaces did not exist before Linux 2.2.
+.SH BUGS
+Some timer settings are specified in jiffies, which is architecture-
+and kernel version-dependent; see
+.BR time (7).
+.P
+There is no way to signal positive feedback from user space.
+This means connection-oriented protocols implemented in user space
+will generate excessive ARP traffic, because ndisc will regularly
+reprobe the MAC address.
+The same problem applies for some kernel protocols (e.g., NFS over UDP).
+.P
+This man page mashes together functionality that is IPv4-specific
+with functionality that is shared between IPv4 and IPv6.
+.SH SEE ALSO
+.BR capabilities (7),
+.BR ip (7),
+.BR arpd (8)
+.P
+RFC\ 826 for a description of ARP.
+RFC\ 2461 for a description of IPv6 neighbor discovery and the base
+algorithms used.
+Linux 2.2+ IPv4 ARP uses the IPv6 algorithms when applicable.
diff --git a/man/man7/ascii.7 b/man/man7/ascii.7
new file mode 100644
index 000000000..ab95c4749
--- /dev/null
+++ b/man/man7/ascii.7
@@ -0,0 +1,169 @@
+'\" t
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Created  1993-04-02 by Michael Haardt (michael@moria.de)
+.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
+.\" Modified 1994-05-15 by Daniel Quinlan (quinlan@yggdrasil.com)
+.\" Modified 1994-11-22 by Daniel Quinlan (quinlan@yggdrasil.com)
+.\" Modified 1995-07-11 by Daniel Quinlan (quinlan@yggdrasil.com)
+.\" Modified 1996-12-18 by Michael Haardt and aeb
+.\" Modified 1999-05-31 by Dimitri Papadopoulos (dpo@club-internet.fr)
+.\" Modified 1999-08-08 by Michael Haardt (michael@moria.de)
+.\" Modified 2004-04-01 by aeb
+.\"
+.TH ascii 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ascii \- ASCII character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+ASCII is the American Standard Code for Information Interchange.
+It is a 7-bit code.
+Many 8-bit codes (e.g., ISO/IEC\~8859-1) contain ASCII as their lower half.
+The international counterpart of ASCII is known as ISO/IEC\~646-IRV.
+.P
+The following table contains the 128 ASCII characters.
+.P
+C program \f(CW\[aq]\eX\[aq]\fP escapes are noted.
+.P
+.EX
+.TS
+l l l l | l l l l.
+Oct	Dec	Hex	Char	Oct	Dec	Hex	Char
+_
+000	0	00	NUL \[aq]\e0\[aq] (null character)	100	64	40	@
+001	1	01	SOH (start of heading)	101	65	41	A
+002	2	02	STX (start of text)	102	66	42	B
+003	3	03	ETX (end of text)	103	67	43	C
+004	4	04	EOT (end of transmission)	104	68	44	D
+005	5	05	ENQ (enquiry)	105	69	45	E
+006	6	06	ACK (acknowledge)	106	70	46	F
+007	7	07	BEL \[aq]\ea\[aq] (bell)	107	71	47	G
+010	8	08	BS  \[aq]\eb\[aq] (backspace)	110	72	48	H
+011	9	09	HT  \[aq]\et\[aq] (horizontal tab)	111	73	49	I
+012	10	0A	LF  \[aq]\en\[aq] (new line)	112	74	4A	J
+013	11	0B	VT  \[aq]\ev\[aq] (vertical tab)	113	75	4B	K
+014	12	0C	FF  \[aq]\ef\[aq] (form feed)	114	76	4C	L
+015	13	0D	CR  \[aq]\er\[aq] (carriage ret)	115	77	4D	M
+016	14	0E	SO  (shift out)	116	78	4E	N
+017	15	0F	SI  (shift in)	117	79	4F	O
+020	16	10	DLE (data link escape)	120	80	50	P
+021	17	11	DC1 (device control 1)	121	81	51	Q
+022	18	12	DC2 (device control 2)	122	82	52	R
+023	19	13	DC3 (device control 3)	123	83	53	S
+024	20	14	DC4 (device control 4)	124	84	54	T
+025	21	15	NAK (negative ack.)	125	85	55	U
+026	22	16	SYN (synchronous idle)	126	86	56	V
+027	23	17	ETB (end of trans. blk)	127	87	57	W
+030	24	18	CAN (cancel)	130	88	58	X
+031	25	19	EM  (end of medium)	131	89	59	Y
+032	26	1A	SUB (substitute)	132	90	5A	Z
+033	27	1B	ESC (escape)	133	91	5B	[
+034	28	1C	FS  (file separator)	134	92	5C	\e  \[aq]\e\e\[aq]
+035	29	1D	GS  (group separator)	135	93	5D	]
+036	30	1E	RS  (record separator)	136	94	5E	\[ha]
+037	31	1F	US  (unit separator)	137	95	5F	\&_
+040	32	20	SPACE	140	96	60	\`
+041	33	21	!	141	97	61	a
+042	34	22	"	142	98	62	b
+043	35	23	#	143	99	63	c
+044	36	24	$	144	100	64	d
+045	37	25	%	145	101	65	e
+046	38	26	&	146	102	66	f
+047	39	27	\[aq]	147	103	67	g
+050	40	28	(	150	104	68	h
+051	41	29	)	151	105	69	i
+052	42	2A	*	152	106	6A	j
+053	43	2B	+	153	107	6B	k
+054	44	2C	,	154	108	6C	l
+055	45	2D	\-	155	109	6D	m
+056	46	2E	.	156	110	6E	n
+057	47	2F	/	157	111	6F	o
+060	48	30	0	160	112	70	p
+061	49	31	1	161	113	71	q
+062	50	32	2	162	114	72	r
+063	51	33	3	163	115	73	s
+064	52	34	4	164	116	74	t
+065	53	35	5	165	117	75	u
+066	54	36	6	166	118	76	v
+067	55	37	7	167	119	77	w
+070	56	38	8	170	120	78	x
+071	57	39	9	171	121	79	y
+072	58	3A	:	172	122	7A	z
+073	59	3B	;	173	123	7B	{
+074	60	3C	<	174	124	7C	|
+075	61	3D	= 	175	125	7D	}
+076	62	3E	>	176	126	7E	\[ti]
+077	63	3F	?	177	127	7F	DEL
+.TE
+.EE
+.SS Tables
+For convenience, below are more compact tables in hex and decimal.
+.P
+.EX
+   2 3 4 5 6 7       30 40 50 60 70 80 90 100 110 120
+ -------------      ---------------------------------
+0:   0 @ P \` p     0:    (  2  <  F  P  Z  d   n   x
+1: ! 1 A Q a q     1:    )  3  =  G  Q  [  e   o   y
+2: " 2 B R b r     2:    *  4  >  H  R  \e  f   p   z
+3: # 3 C S c s     3: !  +  5  ?  I  S  ]  g   q   {
+4: $ 4 D T d t     4: "  ,  6  @  J  T  \[ha]  h   r   |
+5: % 5 E U e u     5: #  \-  7  A  K  U  _  i   s   }
+6: & 6 F V f v     6: $  .  8  B  L  V  \`  j   t   \[ti]
+7: \[aq] 7 G W g w     7: %  /  9  C  M  W  a  k   u  DEL
+8: ( 8 H X h x     8: &  0  :  D  N  X  b  l   v
+9: ) 9 I Y i y     9: \[aq]  1  ;  E  O  Y  c  m   w
+A: * : J Z j z
+B: + ; K [ k {
+C: , < L \e l |
+D: \- = M ] m }
+E: . > N \[ha] n \[ti]
+F: / ? O _ o DEL
+.EE
+.SH NOTES
+.SS History
+/etc/ascii (VII) appears in the UNIX Programmer's Manual.
+.P
+On older terminals, the underscore code is displayed as a left arrow,
+called backarrow, the caret is displayed as an up-arrow and the vertical
+bar has a hole in the middle.
+.P
+Uppercase and lowercase characters differ by just one bit and the
+ASCII character 2 differs from the double quote by just one bit, too.
+That made it much easier to encode characters mechanically or with a
+non-microcontroller-based electronic keyboard and that pairing was found
+on old teletypes.
+.P
+The ASCII standard was published by the United States of America
+Standards Institute (USASI) in 1968.
+.\"
+.\" ASA was the American Standards Association and X3 was an ASA sectional
+.\" committee on computers and data processing.  Its name changed to
+.\" American National Standards Committee X3 (ANSC-X3) and now it is known
+.\" as Accredited Standards Committee X3 (ASC X3).  It is accredited by ANSI
+.\" and administered by ITI.  The subcommittee X3.2 worked on coded
+.\" character sets; the task group working on ASCII appears to have been
+.\" designated X3.2.4.  In 1966, ASA became the United States of America
+.\" Standards Institute (USASI) and published ASCII in 1968.  It became the
+.\" American National Standards Institute (ANSI) in 1969 and is the
+.\" U.S. member body of ISO; private and nonprofit.
+.\"
+.SH SEE ALSO
+.BR charsets (7),
+.BR iso_8859\-1 (7),
+.BR iso_8859\-2 (7),
+.BR iso_8859\-3 (7),
+.BR iso_8859\-4 (7),
+.BR iso_8859\-5 (7),
+.BR iso_8859\-6 (7),
+.BR iso_8859\-7 (7),
+.BR iso_8859\-8 (7),
+.BR iso_8859\-9 (7),
+.BR iso_8859\-10 (7),
+.BR iso_8859\-11 (7),
+.BR iso_8859\-13 (7),
+.BR iso_8859\-14 (7),
+.BR iso_8859\-15 (7),
+.BR iso_8859\-16 (7),
+.BR utf\-8 (7)
diff --git a/man/man7/attributes.7 b/man/man7/attributes.7
new file mode 100644
index 000000000..3b2f59b3a
--- /dev/null
+++ b/man/man7/attributes.7
@@ -0,0 +1,865 @@
+.\" Copyright (c) 2014, Red Hat, Inc
+.\"     Written by Alexandre Oliva <aoliva@redhat.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH attributes 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+attributes \- POSIX safety concepts
+.SH DESCRIPTION
+.\"
+.\"
+.IR Note :
+the text of this man page is based on the material taken from
+the "POSIX Safety Concepts" section of the GNU C Library manual.
+Further details on the topics described here can be found in that
+manual.
+.P
+Various function manual pages include a section ATTRIBUTES
+that describes the safety of calling the function in various contexts.
+This section annotates functions with the following safety markings:
+.TP
+.I MT-Safe
+.I MT-Safe
+or
+Thread-Safe functions are safe to call in the presence
+of other threads.
+MT, in MT-Safe, stands for Multi Thread.
+.IP
+Being MT-Safe does not imply a function is atomic, nor that it uses any
+of the memory synchronization mechanisms POSIX exposes to users.
+It is even possible that calling MT-Safe functions in sequence
+does not yield an MT-Safe combination.
+For example, having a thread call two MT-Safe
+functions one right after the other does not guarantee behavior
+equivalent to atomic execution of a combination of both functions,
+since concurrent calls in other threads may interfere in a destructive way.
+.IP
+Whole-program optimizations that could inline functions across library
+interfaces may expose unsafe reordering, and so performing inlining
+across the GNU C Library interface is not recommended.
+The documented
+MT-Safety status is not guaranteed under whole-program optimization.
+However, functions defined in user-visible headers are designed to be
+safe for inlining.
+.\" .TP
+.\" .I AS-Safe
+.\" .I AS-Safe
+.\" or Async-Signal-Safe functions are safe to call from
+.\" asynchronous signal handlers.
+.\" AS, in AS-Safe, stands for Asynchronous Signal.
+.\"
+.\" Many functions that are AS-Safe may set
+.\" .IR errno ,
+.\" or modify the floating-point environment,
+.\" because their doing so does not make them
+.\" unsuitable for use in signal handlers.
+.\" However, programs could misbehave should asynchronous signal handlers
+.\" modify this thread-local state,
+.\" and the signal handling machinery cannot be counted on to
+.\" preserve it.
+.\" Therefore, signal handlers that call functions that may set
+.\" .I errno
+.\" or modify the floating-point environment
+.\" .I must
+.\" save their original values, and restore them before returning.
+.\" .TP
+.\" .I AC-Safe
+.\" .I AC-Safe
+.\" or Async-Cancel-Safe functions are safe to call when
+.\" asynchronous cancelation is enabled.
+.\" AC in AC-Safe stands for Asynchronous Cancelation.
+.\"
+.\" The POSIX standard defines only three functions to be AC-Safe, namely
+.\" .BR pthread_cancel (3),
+.\" .BR pthread_setcancelstate (3),
+.\" and
+.\" .BR pthread_setcanceltype (3).
+.\" At present the GNU C Library provides no
+.\" guarantees beyond these three functions,
+.\" but does document which functions are presently AC-Safe.
+.\" This documentation is provided for use
+.\" by the GNU C Library developers.
+.\"
+.\" Just like signal handlers, cancelation cleanup routines must configure
+.\" the floating point environment they require.
+.\" The routines cannot assume a floating point environment,
+.\" particularly when asynchronous cancelation is enabled.
+.\" If the configuration of the floating point
+.\" environment cannot be performed atomically then it is also possible that
+.\" the environment encountered is internally inconsistent.
+.TP
+.I MT-Unsafe \" ", " AS-Unsafe ", " AC-Unsafe
+.I MT-Unsafe \" ", " AS-Unsafe ", " AC-Unsafe
+functions are not safe to call in a multithreaded programs.
+.\" functions are not
+.\" safe to call within the safety contexts described above.
+.\" Calling them
+.\" within such contexts invokes undefined behavior.
+.\"
+.\" Functions not explicitly documented as safe in a safety context should
+.\" be regarded as Unsafe.
+.\" .TP
+.\" .I Preliminary
+.\" .I Preliminary
+.\" safety properties are documented, indicating these
+.\" properties may
+.\" .I not
+.\" be counted on in future releases of
+.\" the GNU C Library.
+.\"
+.\" Such preliminary properties are the result of an assessment of the
+.\" properties of our current implementation,
+.\" rather than of what is mandated and permitted
+.\" by current and future standards.
+.\"
+.\" Although we strive to abide by the standards, in some cases our
+.\" implementation is safe even when the standard does not demand safety,
+.\" and in other cases our implementation does not meet the standard safety
+.\" requirements.
+.\" The latter are most likely bugs; the former, when marked
+.\" as
+.\" .IR Preliminary ,
+.\" should not be counted on: future standards may
+.\" require changes that are not compatible with the additional safety
+.\" properties afforded by the current implementation.
+.\"
+.\" Furthermore,
+.\" the POSIX standard does not offer a detailed definition of safety.
+.\" We assume that, by "safe to call", POSIX means that,
+.\" as long as the program does not invoke undefined behavior,
+.\" the "safe to call" function behaves as specified,
+.\" and does not cause other functions to deviate from their specified behavior.
+.\" We have chosen to use its loose
+.\" definitions of safety, not because they are the best definitions to use,
+.\" but because choosing them harmonizes this manual with POSIX.
+.\"
+.\" Please keep in mind that these are preliminary definitions and annotations,
+.\" and certain aspects of the definitions are still under
+.\" discussion and might be subject to clarification or change.
+.\"
+.\" Over time,
+.\" we envision evolving the preliminary safety notes into stable commitments,
+.\" as stable as those of our interfaces.
+.\" As we do, we will remove the
+.\" .I Preliminary
+.\" keyword from safety notes.
+.\" As long as the keyword remains, however,
+.\" they are not to be regarded as a promise of future behavior.
+.P
+Other keywords that appear in safety notes are defined in subsequent sections.
+.\"
+.\"
+.\" .SS Unsafe features
+.\" Functions that are unsafe to call in certain contexts are annotated with
+.\" keywords that document their features that make them unsafe to call.
+.\" AS-Unsafe features in this section indicate the functions are never safe
+.\" to call when asynchronous signals are enabled.
+.\" AC-Unsafe features
+.\" indicate they are never safe to call when asynchronous cancelation is
+.\" .\" enabled.
+.\" There are no MT-Unsafe marks in this section.
+.\" .TP
+.\" .\" .I code
+.\" Functions marked with
+.\" .I lock
+.\" as an AS-Unsafe feature may be
+.\" .\" interrupted by a signal while holding a non-recursive lock.
+.\" If the signal handler calls another such function that takes the same lock,
+.\" the result is a deadlock.
+.\"
+.\" Functions annotated with
+.\" .I lock
+.\" as an AC-Unsafe feature may, if canceled asynchronously,
+.\" fail to release a lock that would have been released if their execution
+.\" had not been interrupted by asynchronous thread cancelation.
+.\" Once a lock is left taken,
+.\" attempts to take that lock will block indefinitely.
+.\" .TP
+.\" .I corrupt
+.\" Functions marked with
+.\" .\" .I corrupt
+.\" as an AS-Unsafe feature may corrupt
+.\" data structures and misbehave when they interrupt,
+.\" or are interrupted by, another such function.
+.\" Unlike functions marked with
+.\" .IR lock ,
+.\" these take recursive locks to avoid MT-Safety problems,
+.\" but this is not enough to stop a signal handler from observing
+.\" a partially-updated data structure.
+.\" Further corruption may arise from the interrupted function's
+.\" failure to notice updates made by signal handlers.
+.\"
+.\" Functions marked with
+.\" .I corrupt
+.\" as an AC-Unsafe feature may leave
+.\" data structures in a corrupt, partially updated state.
+.\" Subsequent uses of the data structure may misbehave.
+.\"
+.\" .\" A special case, probably not worth documenting separately, involves
+.\" .\" reallocing, or even freeing pointers.  Any case involving free could
+.\" .\" be easily turned into an ac-safe leak by resetting the pointer before
+.\" .\" releasing it; I don't think we have any case that calls for this sort
+.\" .\" of fixing.  Fixing the realloc cases would require a new interface:
+.\" .\" instead of @code{ptr=realloc(ptr,size)} we'd have to introduce
+.\" .\" @code{acsafe_realloc(&ptr,size)} that would modify ptr before
+.\" .\" releasing the old memory.  The ac-unsafe realloc could be implemented
+.\" .\" in terms of an internal interface with this semantics (say
+.\" .\" __acsafe_realloc), but since realloc can be overridden, the function
+.\" .\" we call to implement realloc should not be this internal interface,
+.\" .\" but another internal interface that calls __acsafe_realloc if realloc
+.\" .\" was not overridden, and calls the overridden realloc with async
+.\" .\" cancel disabled.  --lxoliva
+.\" .TP
+.\" .I heap
+.\" Functions marked with
+.\" .I heap
+.\" may call heap memory management functions from the
+.\" .BR malloc (3)/ free (3)
+.\" family of functions and are only as safe as those functions.
+.\" This note is thus equivalent to:
+.\"
+.\"     | AS-Unsafe lock | AC-Unsafe lock fd mem |
+.\" .\" @sampsafety{@asunsafe{@asulock{}}@acunsafe{@aculock{} @acsfd{} @acsmem{}}}
+.\" .\"
+.\" .\" Check for cases that should have used plugin instead of or in
+.\" .\" addition to this.  Then, after rechecking gettext, adjust i18n if
+.\" .\" needed.
+.\" .TP
+.\" .I dlopen
+.\" Functions marked with
+.\" .I dlopen
+.\" use the dynamic loader to load
+.\" shared libraries into the current execution image.
+.\" This involves opening files, mapping them into memory,
+.\" allocating additional memory, resolving symbols,
+.\" applying relocations and more,
+.\" all of this while holding internal dynamic loader locks.
+.\"
+.\" The locks are enough for these functions to be AS-Unsafe and AC-Unsafe,
+.\" but other issues may arise.
+.\" At present this is a placeholder for all
+.\" potential safety issues raised by
+.\" .BR dlopen (3).
+.\"
+.\" .\" dlopen runs init and fini sections of the module; does this mean
+.\" .\" dlopen always implies plugin?
+.\" .TP
+.\" .I plugin
+.\" Functions annotated with
+.\" .I plugin
+.\" may run code from plugins that
+.\" may be external to the GNU C Library.
+.\" Such plugin functions are assumed to be
+.\" MT-Safe, AS-Unsafe and AC-Unsafe.
+.\" Examples of such plugins are stack unwinding libraries,
+.\" name service switch (NSS) and character set conversion (iconv) back-ends.
+.\"
+.\" Although the plugins mentioned as examples are all brought in by means
+.\" of dlopen, the
+.\" .I plugin
+.\" keyword does not imply any direct
+.\" involvement of the dynamic loader or the
+.\" .I libdl
+.\" interfaces,
+.\" those are covered by
+.\" .IR dlopen .
+.\" For example, if one function loads a module and finds the addresses
+.\" of some of its functions,
+.\" while another just calls those already-resolved functions,
+.\" the former will be marked with
+.\" .IR dlopen ,
+.\" whereas the latter will get the
+.\" .IR plugin .
+.\" When a single function takes all of these actions, then it gets both marks.
+.\" .TP
+.\" .I i18n
+.\" Functions marked with
+.\" .I i18n
+.\" may call internationalization
+.\" functions of the
+.\" .BR gettext (3)
+.\" family and will be only as safe as those
+.\" functions.
+.\" This note is thus equivalent to:
+.\"
+.\"     | MT-Safe env | AS-Unsafe corrupt heap dlopen | AC-Unsafe corrupt |
+.\"
+.\" .\" @sampsafety{@mtsafe{@mtsenv{}}@asunsafe{@asucorrupt{} @ascuheap{} @ascudlopen{}}@acunsafe{@acucorrupt{}}}
+.\" .TP
+.\" .I timer
+.\" Functions marked with
+.\" .I timer
+.\" use the
+.\" .BR alarm (3)
+.\" function or
+.\" similar to set a time-out for a system call or a long-running operation.
+.\" In a multi-threaded program, there is a risk that the time-out signal
+.\" will be delivered to a different thread,
+.\" thus failing to interrupt the intended thread.
+.\" Besides being MT-Unsafe, such functions are always
+.\" AS-Unsafe, because calling them in signal handlers may interfere with
+.\" timers set in the interrupted code, and AC-Unsafe,
+.\" because there is no safe way to guarantee an earlier timer
+.\" will be reset in case of asynchronous cancelation.
+.\"
+.\"
+.SS Conditionally safe features
+For some features that make functions unsafe to call in certain contexts,
+there are known ways to avoid the safety problem other than
+refraining from calling the function altogether.
+The keywords that follow refer to such features,
+and each of their definitions indicates
+how the whole program needs to be constrained in order to remove the
+safety problem indicated by the keyword.
+Only when all the reasons that
+make a function unsafe are observed and addressed,
+by applying the documented constraints,
+does the function become safe to call in a context.
+.TP
+.I init
+Functions marked with
+.I init
+as an MT-Unsafe feature perform
+MT-Unsafe initialization when they are first called.
+.IP
+Calling such a function at least once in single-threaded mode removes
+this specific cause for the function to be regarded as MT-Unsafe.
+If no other cause for that remains,
+the function can then be safely called after other threads are started.
+.\"
+.\" Functions marked with
+.\" .I init
+.\" as an AS-Unsafe or AC-Unsafe feature use the GNU C Library internal
+.\" .I libc_once
+.\" machinery or similar to initialize internal data structures.
+.\"
+.\" If a signal handler interrupts such an initializer,
+.\" and calls any function that also performs
+.\" .I libc_once
+.\" initialization, it will deadlock if the thread library has been loaded.
+.\"
+.\" Furthermore, if an initializer is partially complete before it is canceled
+.\" or interrupted by a signal whose handler requires the same initialization,
+.\" some or all of the initialization may be performed more than once,
+.\" leaking resources or even resulting in corrupt internal data.
+.\"
+.\" Applications that need to call functions marked with
+.\" .I init
+.\" as an AS-Safety or AC-Unsafe feature should ensure
+.\" the initialization is performed
+.\" before configuring signal handlers or enabling cancelation,
+.\" so that the AS-Safety and AC-Safety issues related with
+.\" .I libc_once
+.\" do not arise.
+.\"
+.\" .\" We may have to extend the annotations to cover conditions in which
+.\" .\" initialization may or may not occur, since an initial call in a safe
+.\" .\" context is no use if the initialization doesn't take place at that
+.\" .\" time: it doesn't remove the risk for later calls.
+.TP
+.I race
+Functions annotated with
+.I race
+as an MT-Safety issue operate on
+objects in ways that may cause data races or similar forms of
+destructive interference out of concurrent execution.
+In some cases,
+the objects are passed to the functions by users;
+in others, they are used by the functions to return values to users;
+in others, they are not even exposed to users.
+.\"
+.\" We consider access to objects passed as (indirect) arguments to
+.\" functions to be data race free.
+.\" The assurance of data race free objects
+.\" is the caller's responsibility.
+.\" We will not mark a function as MT-Unsafe or AS-Unsafe
+.\" if it misbehaves when users fail to take the measures required by
+.\" POSIX to avoid data races when dealing with such objects.
+.\" As a general rule, if a function is documented as reading from
+.\" an object passed (by reference) to it, or modifying it,
+.\" users ought to use memory synchronization primitives
+.\" to avoid data races just as they would should they perform
+.\" the accesses themselves rather than by calling the library function.
+.\" Standard I/O
+.\" .RI ( "FILE *" )
+.\" streams are the exception to the general rule,
+.\" in that POSIX mandates the library to guard against data races
+.\" in many functions that manipulate objects of this specific opaque type.
+.\" We regard this as a convenience provided to users,
+.\" rather than as a general requirement whose expectations
+.\" should extend to other types.
+.\"
+.\" In order to remind users that guarding certain arguments is their
+.\" responsibility, we will annotate functions that take objects of certain
+.\" types as arguments.
+.\" We draw the line for objects passed by users as follows:
+.\" objects whose types are exposed to users,
+.\" and that users are expected to access directly,
+.\" such as memory buffers, strings,
+.\" and various user-visible structured types, do
+.\" .I not
+.\" give reason for functions to be annotated with
+.\" .IR race .
+.\" It would be noisy and redundant with the general requirement,
+.\" and not many would be surprised by the library's lack of internal
+.\" guards when accessing objects that can be accessed directly by users.
+.\"
+.\" As for objects that are opaque or opaque-like,
+.\" in that they are to be manipulated only by passing them
+.\" to library functions (e.g.,
+.\" .IR FILE ,
+.\" .IR DIR ,
+.\" .IR obstack ,
+.\" .IR iconv_t ),
+.\" there might be additional expectations as to internal coordination
+.\" of access by the library.
+.\" We will annotate, with
+.\" .I race
+.\" followed by a colon and the argument name,
+.\" functions that take such objects but that do not take
+.\" care of synchronizing access to them by default.
+.\" For example,
+.\" .I FILE
+.\" stream
+.\" .I unlocked
+.\" functions
+.\" .RB ( unlocked_stdio (3))
+.\" will be annotated,
+.\" but those that perform implicit locking on
+.\" .I FILE
+.\" streams by default will not,
+.\" even though the implicit locking may be disabled on a per-stream basis.
+.\"
+.\" In either case, we will not regard as MT-Unsafe functions that may
+.\" access user-supplied objects in unsafe ways should users fail to ensure
+.\" the accesses are well defined.
+.\" The notion prevails that users are expected to safeguard against
+.\" data races any user-supplied objects that the library accesses
+.\" on their behalf.
+.\"
+.\" .\" The above describes @mtsrace; @mtasurace is described below.
+.\"
+.\" This user responsibility does not apply, however,
+.\" to objects controlled by the library itself,
+.\" such as internal objects and static buffers used
+.\" to return values from certain calls.
+.\" When the library doesn't guard them against concurrent uses,
+.\" these cases are regarded as MT-Unsafe and AS-Unsafe (although the
+.\" .I race
+.\" mark under AS-Unsafe will be omitted
+.\" as redundant with the one under MT-Unsafe).
+.\" As in the case of user-exposed objects,
+.\" the mark may be followed by a colon and an identifier.
+.\" The identifier groups all functions that operate on a
+.\" certain unguarded object; users may avoid the MT-Safety issues related
+.\" with unguarded concurrent access to such internal objects by creating a
+.\" non-recursive mutex related with the identifier,
+.\" and always holding the mutex when calling any function marked
+.\" as racy on that identifier,
+.\" as they would have to should the identifier be
+.\" an object under user control.
+.\" The non-recursive mutex avoids the MT-Safety issue,
+.\" but it trades one AS-Safety issue for another,
+.\" so use in asynchronous signals remains undefined.
+.\"
+.\" When the identifier relates to a static buffer used to hold return values,
+.\" the mutex must be held for as long as the buffer remains in use
+.\" by the caller.
+.\" Many functions that return pointers to static buffers offer reentrant
+.\" variants that store return values in caller-supplied buffers instead.
+.\" In some cases, such as
+.\" .BR tmpname (3),
+.\" the variant is chosen not by calling an alternate entry point,
+.\" but by passing a non-null pointer to the buffer in which the
+.\" returned values are to be stored.
+.\" These variants are generally preferable in multi-threaded programs,
+.\" although some of them are not MT-Safe because of other internal buffers,
+.\" also documented with
+.\" .I race
+.\" notes.
+.TP
+.I const
+Functions marked with
+.I const
+as an MT-Safety issue non-atomically
+modify internal objects that are better regarded as constant,
+because a substantial portion of the GNU C Library accesses them without
+synchronization.
+Unlike
+.IR race ,
+which causes both readers and
+writers of internal objects to be regarded as MT-Unsafe,\" and AS-Unsafe,
+this mark is applied to writers only.
+Writers remain\" equally
+MT-Unsafe\" and AS-Unsafe
+to call,
+but the then-mandatory constness of objects they
+modify enables readers to be regarded as MT-Safe\" and AS-Safe
+(as long as no other reasons for them to be unsafe remain),
+since the lack of synchronization is not a problem when the
+objects are effectively constant.
+.IP
+The identifier that follows the
+.I const
+mark will appear by itself as a safety note in readers.
+Programs that wish to work around this safety issue,
+so as to call writers, may use a non-recursive
+read-write lock
+associated with the identifier, and guard
+.I all
+calls to functions marked with
+.I const
+followed by the identifier with a write lock, and
+.I all
+calls to functions marked with the identifier
+by itself with a read lock.
+.\" The non-recursive locking removes the MT-Safety problem,
+.\" but it trades one AS-Safety problem for another,
+.\" so use in asynchronous signals remains undefined.
+.\"
+.\" .\" But what if, instead of marking modifiers with const:id and readers
+.\" .\" with just id, we marked writers with race:id and readers with ro:id?
+.\" .\" Instead of having to define each instance of 'id', we'd have a
+.\" .\" general pattern governing all such 'id's, wherein race:id would
+.\" .\" suggest the need for an exclusive/write lock to make the function
+.\" .\" safe, whereas ro:id would indicate 'id' is expected to be read-only,
+.\" .\" but if any modifiers are called (while holding an exclusive lock),
+.\" .\" then ro:id-marked functions ought to be guarded with a read lock for
+.\" .\" safe operation.  ro:env or ro:locale, for example, seems to convey
+.\" .\" more clearly the expectations and the meaning, than just env or
+.\" .\" locale.
+.TP
+.I sig
+Functions marked with
+.I sig
+as a MT-Safety issue
+.\" (that implies an identical AS-Safety issue, omitted for brevity)
+may temporarily install a signal handler for internal purposes,
+which may interfere with other uses of the signal,
+identified after a colon.
+.IP
+This safety problem can be worked around by ensuring that no other uses
+of the signal will take place for the duration of the call.
+Holding a non-recursive mutex while calling all functions that use the same
+temporary signal;
+blocking that signal before the call and resetting its
+handler afterwards is recommended.
+.\"
+.\" There is no safe way to guarantee the original signal handler is
+.\" restored in case of asynchronous cancelation,
+.\" therefore so-marked functions are also AC-Unsafe.
+.\"
+.\" .\" fixme: at least deferred cancelation should get it right, and would
+.\" .\" obviate the restoring bit below, and the qualifier above.
+.\"
+.\" Besides the measures recommended to work around the
+.\" MT-Safety and AS-Safety problem,
+.\" in order to avert the cancelation problem,
+.\" disabling asynchronous cancelation
+.\" .I and
+.\" installing a cleanup handler to restore the signal to the desired state
+.\" and to release the mutex are recommended.
+.TP
+.I term
+Functions marked with
+.I term
+as an MT-Safety issue may change the
+terminal settings in the recommended way, namely: call
+.BR tcgetattr (3),
+modify some flags, and then call
+.BR tcsetattr (3),
+this creates a window in which changes made by other threads are lost.
+Thus, functions marked with
+.I term
+are MT-Unsafe.
+.\" The same window enables changes made by asynchronous signals to be lost.
+.\" These functions are also AS-Unsafe,
+.\" but the corresponding mark is omitted as redundant.
+.IP
+It is thus advisable for applications using the terminal to avoid
+concurrent and reentrant interactions with it,
+by not using it in signal handlers or blocking signals that might use it,
+and holding a lock while calling these functions and interacting
+with the terminal.
+This lock should also be used for mutual exclusion with
+functions marked with
+.IR race:tcattr(fd) ,
+where
+.I fd
+is a file descriptor for the controlling terminal.
+The caller may use a single mutex for simplicity,
+or use one mutex per terminal,
+even if referenced by different file descriptors.
+.\"
+.\" Functions marked with
+.\" .I term
+.\" as an AC-Safety issue are supposed to
+.\" restore terminal settings to their original state,
+.\" after temporarily changing them, but they may fail to do so if canceled.
+.\"
+.\" .\" fixme: at least deferred cancelation should get it right, and would
+.\" .\" obviate the restoring bit below, and the qualifier above.
+.\"
+.\" Besides the measures recommended to work around the
+.\" MT-Safety and AS-Safety problem,
+.\" in order to avert the cancelation problem,
+.\" disabling asynchronous cancelation
+.\" .I and
+.\" installing a cleanup handler to
+.\" restore the terminal settings to the original state and to release the
+.\" mutex are recommended.
+.\"
+.\"
+.SS Other safety remarks
+Additional keywords may be attached to functions,
+indicating features that do not make a function unsafe to call,
+but that may need to be taken into account in certain classes of programs:
+.TP
+.I locale
+Functions annotated with
+.I locale
+as an MT-Safety issue read from
+the locale object without any form of synchronization.
+Functions
+annotated with
+.I locale
+called concurrently with locale changes may
+behave in ways that do not correspond to any of the locales active
+during their execution, but an unpredictable mix thereof.
+.IP
+We do not mark these functions as MT-Unsafe,\" or AS-Unsafe,
+however,
+because functions that modify the locale object are marked with
+.I const:locale
+and regarded as unsafe.
+Being unsafe, the latter are not to be called when multiple threads
+are running or asynchronous signals are enabled,
+and so the locale can be considered effectively constant
+in these contexts,
+which makes the former safe.
+.\" Should the locking strategy suggested under @code{const} be used,
+.\" failure to guard locale uses is not as fatal as data races in
+.\" general: unguarded uses will @emph{not} follow dangling pointers or
+.\" access uninitialized, unmapped or recycled memory.  Each access will
+.\" read from a consistent locale object that is or was active at some
+.\" point during its execution.  Without synchronization, however, it
+.\" cannot even be assumed that, after a change in locale, earlier
+.\" locales will no longer be used, even after the newly-chosen one is
+.\" used in the thread.  Nevertheless, even though unguarded reads from
+.\" the locale will not violate type safety, functions that access the
+.\" locale multiple times may invoke all sorts of undefined behavior
+.\" because of the unexpected locale changes.
+.TP
+.I env
+Functions marked with
+.I env
+as an MT-Safety issue access the
+environment with
+.BR getenv (3)
+or similar, without any guards to ensure
+safety in the presence of concurrent modifications.
+.IP
+We do not mark these functions as MT-Unsafe,\" or AS-Unsafe,
+however,
+because functions that modify the environment are all marked with
+.I const:env
+and regarded as unsafe.
+Being unsafe, the latter are not to be called when multiple threads
+are running or asynchronous signals are enabled,
+and so the environment can be considered
+effectively constant in these contexts,
+which makes the former safe.
+.TP
+.I hostid
+The function marked with
+.I hostid
+as an MT-Safety issue reads from the system-wide data structures that
+hold the "host ID" of the machine.
+These data structures cannot generally be modified atomically.
+Since it is expected that the "host ID" will not normally change,
+the function that reads from it
+.RB ( gethostid (3))
+is regarded as safe,
+whereas the function that modifies it
+.RB ( sethostid (3))
+is marked with
+.IR const:hostid ,
+indicating it may require special care if it is to be called.
+In this specific case,
+the special care amounts to system-wide
+(not merely intra-process) coordination.
+.TP
+.I sigintr
+Functions marked with
+.I sigintr
+as an MT-Safety issue access the
+GNU C Library
+.I _sigintr
+internal data structure without any guards to ensure
+safety in the presence of concurrent modifications.
+.IP
+We do not mark these functions as MT-Unsafe,\" or AS-Unsafe,
+however,
+because functions that modify this data structure are all marked with
+.I const:sigintr
+and regarded as unsafe.
+Being unsafe,
+the latter are not to be called when multiple threads are
+running or asynchronous signals are enabled,
+and so the data structure can be considered
+effectively constant in these contexts,
+which makes the former safe.
+.\" .TP
+.\" .I fd
+.\" Functions annotated with
+.\" .I fd
+.\" as an AC-Safety issue may leak file
+.\" descriptors if asynchronous thread cancelation interrupts their
+.\" execution.
+.\"
+.\" Functions that allocate or deallocate file descriptors will generally be
+.\" marked as such.
+.\" Even if they attempted to protect the file descriptor
+.\" allocation and deallocation with cleanup regions,
+.\" allocating a new descriptor and storing its number where the cleanup region
+.\" could release it cannot be performed as a single atomic operation.
+.\" Similarly,
+.\" releasing the descriptor and taking it out of the data structure
+.\" normally responsible for releasing it cannot be performed atomically.
+.\" There will always be a window in which the descriptor cannot be released
+.\" because it was not stored in the cleanup handler argument yet,
+.\" or it was already taken out before releasing it.
+.\" .\" It cannot be taken out after release:
+.\" an open descriptor could mean either that the descriptor still
+.\" has to be closed,
+.\" or that it already did so but the descriptor was
+.\" reallocated by another thread or signal handler.
+.\"
+.\" Such leaks could be internally avoided, with some performance penalty,
+.\" by temporarily disabling asynchronous thread cancelation.
+.\" However,
+.\" since callers of allocation or deallocation functions would have to do
+.\" this themselves, to avoid the same sort of leak in their own layer,
+.\" it makes more sense for the library to assume they are taking care of it
+.\" than to impose a performance penalty that is redundant when the problem
+.\" is solved in upper layers, and insufficient when it is not.
+.\"
+.\" This remark by itself does not cause a function to be regarded as
+.\" AC-Unsafe.
+.\" However, cumulative effects of such leaks may pose a
+.\" problem for some programs.
+.\" If this is the case,
+.\" suspending asynchronous cancelation for the duration of calls
+.\" to such functions is recommended.
+.\" .TP
+.\" .I mem
+.\" Functions annotated with
+.\" .I mem
+.\" as an AC-Safety issue may leak
+.\" memory if asynchronous thread cancelation interrupts their execution.
+.\"
+.\" The problem is similar to that of file descriptors: there is no atomic
+.\" interface to allocate memory and store its address in the argument to a
+.\" cleanup handler,
+.\" or to release it and remove its address from that argument,
+.\" without at least temporarily disabling asynchronous cancelation,
+.\" which these functions do not do.
+.\"
+.\" This remark does not by itself cause a function to be regarded as
+.\" generally AC-Unsafe.
+.\" However, cumulative effects of such leaks may be
+.\" severe enough for some programs that disabling asynchronous cancelation
+.\" for the duration of calls to such functions may be required.
+.TP
+.I cwd
+Functions marked with
+.I cwd
+as an MT-Safety issue may temporarily
+change the current working directory during their execution,
+which may cause relative pathnames to be resolved in unexpected ways in
+other threads or within asynchronous signal or cancelation handlers.
+.IP
+This is not enough of a reason to mark so-marked functions as MT-Unsafe,
+.\" or AS-Unsafe,
+but when this behavior is optional (e.g.,
+.BR nftw (3)
+with
+.BR FTW_CHDIR ),
+avoiding the option may be a good alternative to
+using full pathnames or file descriptor-relative (e.g.,
+.BR openat (2))
+system calls.
+.\" .TP
+.\" .I !posix
+.\" This remark, as an MT-Safety, AS-Safety or AC-Safety
+.\" note to a function,
+.\" indicates the safety status of the function is known to differ
+.\" from the specified status in the POSIX standard.
+.\" For example, POSIX does not require a function to be Safe,
+.\" but our implementation is, or vice-versa.
+.\"
+.\" For the time being, the absence of this remark does not imply the safety
+.\" properties we documented are identical to those mandated by POSIX for
+.\" the corresponding functions.
+.TP
+.I :identifier
+Annotations may sometimes be followed by identifiers,
+intended to group several functions that, for example,
+access the data structures in an unsafe way, as in
+.I race
+and
+.IR const ,
+or to provide more specific information,
+such as naming a signal in a function marked with
+.IR sig .
+It is envisioned that it may be applied to
+.I lock
+and
+.I corrupt
+as well in the future.
+.IP
+In most cases, the identifier will name a set of functions,
+but it may name global objects or function arguments,
+or identifiable properties or logical components associated with them,
+with a notation such as, for example,
+.I :buf(arg)
+to denote a buffer associated with the argument
+.IR arg ,
+or
+.I :tcattr(fd)
+to denote the terminal attributes of a file descriptor
+.IR fd .
+.IP
+The most common use for identifiers is to provide logical groups of
+functions and arguments that need to be protected by the same
+synchronization primitive in order to ensure safe operation in a given
+context.
+.TP
+.I /condition
+Some safety annotations may be conditional,
+in that they only apply if a boolean expression involving arguments,
+global variables or even the underlying kernel evaluates to true.
+.\" Such conditions as
+.\" .I /hurd
+.\" or
+.\" .I /!linux!bsd
+.\" indicate the preceding marker only
+.\" applies when the underlying kernel is the HURD,
+.\" or when it is neither Linux nor a BSD kernel, respectively.
+For example,
+.I /!ps
+and
+.I /one_per_line
+indicate the preceding marker only applies when argument
+.I ps
+is NULL, or global variable
+.I one_per_line
+is nonzero.
+.IP
+When all marks that render a function unsafe are
+adorned with such conditions,
+and none of the named conditions hold,
+then the function can be regarded as safe.
+.SH SEE ALSO
+.BR pthreads (7),
+.BR signal\-safety (7)
diff --git a/man/man7/boot.7 b/man/man7/boot.7
new file mode 100644
index 000000000..b66f6596e
--- /dev/null
+++ b/man/man7/boot.7
@@ -0,0 +1,230 @@
+.\" Written by Oron Peled <oron@actcom.co.il>.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" I tried to be as much generic in the description as possible:
+.\" - General boot sequence is applicable to almost any
+.\" OS/Machine (DOS/PC, Linux/PC, Solaris/SPARC, CMS/S390)
+.\" - kernel and init(1) is applicable to almost any UNIX/Linux
+.\" - boot scripts are applicable to SYSV-R4 based UNIX/Linux
+.\"
+.\" Modified 2004-11-03 patch from Martin Schulze <joey@infodrom.org>
+.\"
+.TH boot 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+boot \- System bootup process based on UNIX System V Release 4
+.SH DESCRIPTION
+The \fBbootup process\fR (or "\fBboot sequence\fR") varies in details
+among systems, but can be roughly divided into phases controlled by
+the following components:
+.IP (1) 5
+hardware
+.IP (2)
+operating system (OS) loader
+.IP (3)
+kernel
+.IP (4)
+root user-space process (\fIinit\fR and \fIinittab\fR)
+.IP (5)
+boot scripts
+.P
+Each of these is described below in more detail.
+.SS Hardware
+After power-on or hard reset, control is given
+to a program stored in read-only memory (normally
+PROM); for historical reasons involving the personal
+computer, this program is often called "the \fBBIOS\fR".
+.P
+This program normally performs a basic self-test of the
+machine and accesses nonvolatile memory to read
+further parameters.
+This memory in the PC is
+battery-backed CMOS memory, so most people
+refer to it as "the \fBCMOS\fR"; outside
+of the PC world, it is usually called "the \fBNVRAM\fR"
+(nonvolatile RAM).
+.P
+The parameters stored in the NVRAM vary among
+systems, but as a minimum, they should specify
+which device can supply an OS loader, or at least which
+devices may be probed for one; such a device is known as "the
+\fBboot device\fR".
+The hardware boot stage loads the OS loader from a fixed position on
+the boot device, and then transfers control to it.
+.TP
+Note:
+The device from which the OS loader is read may be attached via a network,
+in which case the details of booting are further specified by protocols such as
+DHCP, TFTP, PXE, Etherboot, etc.
+.SS OS loader
+The main job of the OS loader is to locate the kernel
+on some device, load it, and run it.
+Most OS loaders allow
+interactive use, in order to enable specification of an alternative
+kernel (maybe a backup in case the one last compiled
+isn't functioning) and to pass optional parameters
+to the kernel.
+.P
+In a traditional PC, the OS loader is located in the initial 512-byte block
+of the boot device; this block is known as "the \fBMBR\fR"
+(Master Boot Record).
+.P
+In most systems, the OS loader is very
+limited due to various constraints.
+Even on non-PC systems,
+there are some limitations on the size and complexity
+of this loader, but the size limitation of the PC MBR
+(512 bytes, including the partition table) makes it
+almost impossible to squeeze much functionality into it.
+.P
+Therefore, most systems split the role of loading the OS between
+a primary OS loader and a secondary OS loader; this secondary
+OS loader may be located within a larger portion of persistent
+storage, such as a disk partition.
+.P
+In Linux, the OS loader is often
+.BR grub (8)
+(an alternative is
+.BR lilo (8)).
+.SS Kernel
+When the kernel is loaded, it initializes various components of
+the computer and operating system; each portion of software
+responsible for such a task is usually consider "a \fBdriver\fR" for
+the applicable component.
+The kernel starts the virtual memory
+swapper (it is a kernel process, called "kswapd" in a modern Linux
+kernel), and mounts some filesystem at the root path,
+.IR / .
+.P
+Some of the parameters that may be passed to the kernel
+relate to these activities (for example, the default root filesystem
+can be overridden); for further information
+on Linux kernel parameters, read
+.BR bootparam (7).
+.P
+Only then does the kernel create the initial userland
+process, which is given the number 1 as its
+.B PID
+(process ID).
+Traditionally, this process executes the
+program
+.IR /sbin/init ,
+to which are passed the parameters that haven't already been
+handled by the kernel.
+.SS Root user-space process
+.TP
+Note:
+The following description applies to an OS based on UNIX System V Release 4.
+However, a number of widely used systems have adopted a related but
+fundamentally different approach known as
+.BR systemd (1),
+for which the bootup process is detailed in its associated
+.BR bootup (7).
+.P
+When
+.I /sbin/init
+starts, it reads
+.I /etc/inittab
+for further instructions.
+This file defines what should be run when the
+.I /sbin/init
+program is instructed to enter a particular run level, giving
+the administrator an easy way to establish an environment
+for some usage; each run level is associated with a set of services
+(for example, run level
+.B S
+is single-user mode,
+and run level
+.B 2
+entails running most network services).
+.P
+The administrator may change the current run level via
+.BR init (1),
+and query the current run level via
+.BR runlevel (8).
+.P
+However, since it is not convenient to manage individual services
+by editing this file,
+.I /etc/inittab
+only bootstraps a set of scripts
+that actually start/stop the individual services.
+.SS Boot scripts
+.TP
+Note:
+The following description applies to an OS based on UNIX System V Release 4.
+However, a number of widely used systems (Slackware Linux, FreeBSD, OpenBSD)
+have a somewhat different scheme for boot scripts.
+.P
+For each managed service (mail, nfs server, cron, etc.), there is
+a single startup script located in a specific directory
+.RI ( /etc/init.d
+in most versions of Linux).
+Each of these scripts accepts as a single argument
+the word "start" (causing it to start the service) or the word
+\&"stop" (causing it to stop the service).
+The script may optionally
+accept other "convenience" parameters (e.g., "restart" to stop and then
+start, "status" to display the service status, etc.).
+Running the script
+without parameters displays the possible arguments.
+.SS Sequencing directories
+To make specific scripts start/stop at specific run levels and in a
+specific order, there are \fIsequencing directories\fR, normally
+of the form  \fI/etc/rc[0\-6S].d\fR.
+In each of these directories,
+there are links (usually symbolic) to the scripts in the \fI/etc/init.d\fR
+directory.
+.P
+A primary script (usually \fI/etc/rc\fR) is called from
+.BR inittab (5);
+this primary script calls each service's script via a link in the
+relevant sequencing directory.
+Each link whose name begins with \[aq]S\[aq] is called with
+the argument "start" (thereby starting the service).
+Each link whose name begins with \[aq]K\[aq] is called with
+the argument "stop" (thereby stopping the service).
+.P
+To define the starting or stopping order within the same run level,
+the name of a link contains an \fBorder-number\fR.
+Also, for clarity, the name of a link usually
+ends with the name of the service to which it refers.
+For example,
+the link \fI/etc/rc2.d/S80sendmail\fR starts the
+.BR sendmail (8)
+service on
+run level 2.
+This happens after \fI/etc/rc2.d/S12syslog\fR is run
+but before \fI/etc/rc2.d/S90xfs\fR is run.
+.P
+To manage these links is to manage the boot order and run levels;
+under many systems, there are tools to help with this task
+(e.g.,
+.BR chkconfig (8)).
+.SS Boot configuration
+A program that provides a service is often called a "\fBdaemon\fR".
+Usually, a daemon may receive various command-line options
+and parameters.
+To allow a system administrator to change these
+inputs without editing an entire boot script,
+some separate configuration file is used, and is located in a specific
+directory where an associated boot script may find it
+(\fI/etc/sysconfig\fR on older Red Hat systems).
+.P
+In older UNIX systems, such a file contained the actual command line
+options for a daemon, but in modern Linux systems (and also
+in HP-UX), it just contains shell variables.
+A boot script in \fI/etc/init.d\fR reads and includes its configuration
+file (that is, it "\fBsources\fR" its configuration file) and then uses
+the variable values.
+.SH FILES
+.IR /etc/init.d/ ,
+.IR /etc/rc[S0\-6].d/ ,
+.I /etc/sysconfig/
+.SH SEE ALSO
+.BR init (1),
+.BR systemd (1),
+.BR inittab (5),
+.BR bootparam (7),
+.BR bootup (7),
+.BR runlevel (8),
+.BR shutdown (8)
diff --git a/man/man7/bootparam.7 b/man/man7/bootparam.7
new file mode 100644
index 000000000..98a5d65fd
--- /dev/null
+++ b/man/man7/bootparam.7
@@ -0,0 +1,664 @@
+.\" Copyright (c) 1995,1997 Paul Gortmaker and Andries Brouwer
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" This man page written 950814 by aeb, based on Paul Gortmaker's HOWTO
+.\" (dated v1.0.1, 15/08/95).
+.\" Major update, aeb, 970114.
+.\"
+.TH bootparam 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bootparam \- introduction to boot time parameters of the Linux kernel
+.SH DESCRIPTION
+The Linux kernel accepts certain 'command-line options' or 'boot time
+parameters' at the moment it is started.
+In general, this is used to
+supply the kernel with information about hardware parameters that
+the kernel would not be able to determine on its own, or to avoid/override
+the values that the kernel would otherwise detect.
+.P
+When the kernel is booted directly by the BIOS,
+you have no opportunity to specify any parameters.
+So, in order to take advantage of this possibility you have to
+use a boot loader that is able to pass parameters, such as GRUB.
+.SS The argument list
+The kernel command line is parsed into a list of strings
+(boot arguments) separated by spaces.
+Most of the boot arguments have the form:
+.P
+.in +4n
+.EX
+name[=value_1][,value_2]...[,value_10]
+.EE
+.in
+.P
+where 'name' is a unique keyword that is used to identify what part of
+the kernel the associated values (if any) are to be given to.
+Note the limit of 10 is real, as the present code handles only 10 comma
+separated parameters per keyword.
+(However, you can reuse the same
+keyword with up to an additional 10 parameters in unusually
+complicated situations, assuming the setup function supports it.)
+.P
+Most of the sorting is coded in the kernel source file
+.IR init/main.c .
+First, the kernel
+checks to see if the argument is any of the special arguments 'root=',
+\&'nfsroot=', 'nfsaddrs=', 'ro', 'rw', 'debug', or 'init'.
+The meaning of these special arguments is described below.
+.P
+Then it walks a list of setup functions
+to see if the specified argument string (such as 'foo') has
+been associated with a setup function ('foo_setup()') for a particular
+device or part of the kernel.
+If you passed the kernel the line
+foo=3,4,5,6 then the kernel would search the bootsetups array to see
+if 'foo' was registered.
+If it was, then it would call the setup
+function associated with 'foo' (foo_setup()) and hand it the arguments
+3, 4, 5, and 6 as given on the kernel command line.
+.P
+Anything of the form 'foo=bar' that is not accepted as a setup function
+as described above is then interpreted as an environment variable to
+be set.
+A (useless?) example would be to use 'TERM=vt100' as a boot
+argument.
+.P
+Any remaining arguments that were not picked up by the kernel and were
+not interpreted as environment variables are then passed onto PID 1,
+which is usually the
+.BR init (1)
+program.
+The most common argument that
+is passed to the
+.I init
+process is the word 'single' which instructs it
+to boot the computer in single user mode, and not launch all the usual
+daemons.
+Check the manual page for the version of
+.BR init (1)
+installed on
+your system to see what arguments it accepts.
+.SS General non-device-specific boot arguments
+.TP
+.B "'init=...'"
+This sets the initial command to be executed by the kernel.
+If this is not set, or cannot be found, the kernel will try
+.IR /sbin/init ,
+then
+.IR /etc/init ,
+then
+.IR /bin/init ,
+then
+.I /bin/sh
+and panic if all of this fails.
+.TP
+.B "'nfsaddrs=...'"
+This sets the NFS boot address to the given string.
+This boot address is used in case of a net boot.
+.TP
+.B "'nfsroot=...'"
+This sets the NFS root name to the given string.
+If this string
+does not begin with '/' or ',' or a digit, then it is prefixed by
+\&'/tftpboot/'.
+This root name is used in case of a net boot.
+.TP
+.B "'root=...'"
+This argument tells the kernel what device is to be used as the root
+filesystem while booting.
+The default of this setting is determined
+at compile time, and usually is the value of the root device of the
+system that the kernel was built on.
+To override this value, and
+select the second floppy drive as the root device, one would
+use 'root=/dev/fd1'.
+.IP
+The root device can be specified symbolically or numerically.
+A symbolic specification has the form
+.IR /dev/XXYN ,
+where XX designates
+the device type (e.g., 'hd' for ST-506 compatible hard disk, with Y in
+\&'a'\[en]'d'; 'sd' for SCSI compatible disk, with Y in 'a'\[en]'e'),
+Y the driver letter or
+number, and N the number (in decimal) of the partition on this device.
+.IP
+Note that this has nothing to do with the designation of these
+devices on your filesystem.
+The '/dev/' part is purely conventional.
+.IP
+The more awkward and less portable numeric specification of the above
+possible root devices in major/minor format is also accepted.
+(For example,
+.I /dev/sda3
+is major 8, minor 3, so you could use 'root=0x803' as an
+alternative.)
+.TP
+.B 'rootdelay='
+This parameter sets the delay (in seconds) to pause before attempting
+to mount the root filesystem.
+.TP
+.B 'rootflags=...'
+This parameter sets the mount option string for the root filesystem
+(see also
+.BR fstab (5)).
+.TP
+.B 'rootfstype=...'
+The 'rootfstype' option tells the kernel to mount the root filesystem as
+if it where of the type specified.
+This can be useful (for example) to
+mount an ext3 filesystem as ext2 and then remove the journal in the root
+filesystem, in fact reverting its format from ext3 to ext2 without the
+need to boot the box from alternate media.
+.TP
+.BR 'ro' " and " 'rw'
+The 'ro' option tells the kernel to mount the root filesystem
+as 'read-only' so that filesystem consistency check programs (fsck)
+can do their work on a quiescent filesystem.
+No processes can
+write to files on the filesystem in question until it is 'remounted'
+as read/write capable, for example, by 'mount \-w \-n \-o remount /'.
+(See also
+.BR mount (8).)
+.IP
+The 'rw' option tells the kernel to mount the root filesystem read/write.
+This is the default.
+.TP
+.B "'resume=...'"
+This tells the kernel the location of
+the suspend-to-disk data that you want the machine to resume from
+after hibernation.
+Usually, it is the same as your swap partition or file.
+Example:
+.IP
+.in +4n
+.EX
+resume=/dev/hda2
+.EE
+.in
+.TP
+.B "'reserve=...'"
+This is used to protect I/O port regions from probes.
+The form of the command is:
+.IP
+.in +4n
+.EX
+.BI reserve= iobase,extent[,iobase,extent]...
+.EE
+.in
+.IP
+In some machines it may be necessary to prevent device drivers from
+checking for devices (auto-probing) in a specific region.
+This may be
+because of hardware that reacts badly to the probing, or hardware
+that would be mistakenly identified, or merely
+hardware you don't want the kernel to initialize.
+.IP
+The reserve boot-time argument specifies an I/O port region that
+shouldn't be probed.
+A device driver will not probe a reserved region,
+unless another boot argument explicitly specifies that it do so.
+.IP
+For example, the boot line
+.IP
+.in +4n
+.EX
+reserve=0x300,32  blah=0x300
+.EE
+.in
+.IP
+keeps all device drivers except the driver for 'blah' from probing
+0x300\-0x31f.
+.TP
+.B "'panic=N'"
+By default, the kernel will not reboot after a panic, but this option
+will cause a kernel reboot after N seconds (if N is greater than zero).
+This panic timeout can also be set by
+.IP
+.in +4n
+.EX
+echo N > /proc/sys/kernel/panic
+.EE
+.in
+.TP
+.B "'reboot=[warm|cold][,[bios|hard]]'"
+Since Linux 2.0.22, a reboot is by default a cold reboot.
+One asks for the old default with 'reboot=warm'.
+(A cold reboot may be required to reset certain hardware,
+but might destroy not yet written data in a disk cache.
+A warm reboot may be faster.)
+By default, a reboot is hard, by asking the keyboard controller
+to pulse the reset line low, but there is at least one type
+of motherboard where that doesn't work.
+The option 'reboot=bios' will
+instead jump through the BIOS.
+.TP
+.BR 'nosmp' " and " 'maxcpus=N'
+(Only when __SMP__ is defined.)
+A command-line option of 'nosmp' or 'maxcpus=0' will disable SMP
+activation entirely; an option 'maxcpus=N' limits the maximum number
+of CPUs activated in SMP mode to N.
+.SS Boot arguments for use by kernel developers
+.TP
+.B "'debug'"
+Kernel messages are handed off to a daemon (e.g.,
+.BR klogd (8)
+or similar) so that they may be logged to disk.
+Messages with a priority above
+.I console_loglevel
+are also printed on the console.
+(For a discussion of log levels, see
+.BR syslog (2).)
+By default,
+.I console_loglevel
+is set to log messages at levels higher than
+.BR KERN_DEBUG .
+This boot argument will cause the kernel to also
+print messages logged at level
+.BR KERN_DEBUG .
+The console loglevel can also be set on a booted system via the
+.I /proc/sys/kernel/printk
+file (described in
+.BR syslog (2)),
+the
+.BR syslog (2)
+.B SYSLOG_ACTION_CONSOLE_LEVEL
+operation, or
+.BR dmesg (8).
+.TP
+.B "'profile=N'"
+It is possible to enable a kernel profiling function,
+if one wishes to find out where the kernel is spending its CPU cycles.
+Profiling is enabled by setting the variable
+.I prof_shift
+to a nonzero value.
+This is done either by specifying
+.B CONFIG_PROFILE
+at compile time, or by giving the 'profile=' option.
+Now the value that
+.I prof_shift
+gets will be N, when given, or
+.BR CONFIG_PROFILE_SHIFT ,
+when that is given, or 2, the default.
+The significance of this variable is that it
+gives the granularity of the profiling: each clock tick, if the
+system was executing kernel code, a counter is incremented:
+.IP
+.in +4n
+.EX
+profile[address >> prof_shift]++;
+.EE
+.in
+.IP
+The raw profiling information can be read from
+.IR /proc/profile .
+Probably you'll want to use a tool such as readprofile.c to digest it.
+Writing to
+.I /proc/profile
+will clear the counters.
+.SS Boot arguments for ramdisk use
+(Only if the kernel was compiled with
+.BR CONFIG_BLK_DEV_RAM .)
+In general it is a bad idea to use a ramdisk under Linux\[em]the
+system will use available memory more efficiently itself.
+But while booting,
+it is often useful to load the floppy contents into a
+ramdisk.
+One might also have a system in which first
+some modules (for filesystem or hardware) must be loaded
+before the main disk can be accessed.
+.IP
+In Linux 1.3.48, ramdisk handling was changed drastically.
+Earlier, the memory was allocated statically, and there was
+a 'ramdisk=N' parameter to tell its size.
+(This could also be set in the kernel image at compile time.)
+These days ram disks use the buffer cache, and grow dynamically.
+For a lot of information on the current ramdisk
+setup, see the kernel source file
+.I Documentation/blockdev/ramdisk.txt
+.RI ( Documentation/ramdisk.txt
+in older kernels).
+.IP
+There are four parameters, two boolean and two integral.
+.TP
+.B "'load_ramdisk=N'"
+If N=1, do load a ramdisk.
+If N=0, do not load a ramdisk.
+(This is the default.)
+.TP
+.B "'prompt_ramdisk=N'"
+If N=1, do prompt for insertion of the floppy.
+(This is the default.)
+If N=0, do not prompt.
+(Thus, this parameter is never needed.)
+.TP
+.BR 'ramdisk_size=N' " or (obsolete) " 'ramdisk=N'
+Set the maximal size of the ramdisk(s) to N kB.
+The default is 4096 (4\ MB).
+.TP
+.B "'ramdisk_start=N'"
+Sets the starting block number (the offset on the floppy where
+the ramdisk starts) to N.
+This is needed in case the ramdisk follows a kernel image.
+.TP
+.B "'noinitrd'"
+(Only if the kernel was compiled with
+.B CONFIG_BLK_DEV_RAM
+and
+.BR CONFIG_BLK_DEV_INITRD .)
+These days it is possible to compile the kernel to use initrd.
+When this feature is enabled, the boot process will load the kernel
+and an initial ramdisk; then the kernel converts initrd into
+a "normal" ramdisk, which is mounted read-write as root device;
+then
+.I /linuxrc
+is executed; afterward the "real" root filesystem is mounted,
+and the initrd filesystem is moved over to
+.IR /initrd ;
+finally
+the usual boot sequence (e.g., invocation of
+.IR /sbin/init )
+is performed.
+.IP
+For a detailed description of the initrd feature, see the kernel source file
+.I Documentation/admin\-guide/initrd.rst
+.\" commit 9d85025b0418163fae079c9ba8f8445212de8568
+(or
+.I Documentation/initrd.txt
+before Linux 4.10).
+.IP
+The 'noinitrd' option tells the kernel that although it was compiled for
+operation with initrd, it should not go through the above steps, but
+leave the initrd data under
+.IR /dev/initrd .
+(This device can be used only once: the data is freed as soon as
+the last process that used it has closed
+.IR /dev/initrd .)
+.SS Boot arguments for SCSI devices
+General notation for this section:
+.P
+.I iobase
+-- the first I/O port that the SCSI host occupies.
+These are specified in hexadecimal notation,
+and usually lie in the range from 0x200 to 0x3ff.
+.P
+.I irq
+-- the hardware interrupt that the card is configured to use.
+Valid values will be dependent on the card in question, but will
+usually be 5, 7, 9, 10, 11, 12, and 15.
+The other values are usually
+used for common peripherals like IDE hard disks, floppies, serial
+ports, and so on.
+.P
+.I scsi\-id
+-- the ID that the host adapter uses to identify itself on the
+SCSI bus.
+Only some host adapters allow you to change this value, as
+most have it permanently specified internally.
+The usual default value
+is 7, but the Seagate and Future Domain TMC-950 boards use 6.
+.P
+.I parity
+-- whether the SCSI host adapter expects the attached devices
+to supply a parity value with all information exchanges.
+Specifying a one indicates parity checking is enabled,
+and a zero disables parity checking.
+Again, not all adapters will support selection of parity
+behavior as a boot argument.
+.TP
+.B "'max_scsi_luns=...'"
+A SCSI device can have a number of 'subdevices' contained within
+itself.
+The most common example is one of the new SCSI CD-ROMs that
+handle more than one disk at a time.
+Each CD is addressed as a
+\&'Logical Unit Number' (LUN) of that particular device.
+But most
+devices, such as hard disks, tape drives, and such are only one device,
+and will be assigned to LUN zero.
+.IP
+Some poorly designed SCSI devices cannot handle being probed for
+LUNs not equal to zero.
+Therefore, if the compile-time flag
+.B CONFIG_SCSI_MULTI_LUN
+is not set, newer kernels will by default probe only LUN zero.
+.IP
+To specify the number of probed LUNs at boot, one enters
+\&'max_scsi_luns=n' as a boot arg, where n is a number between one and
+eight.
+To avoid problems as described above, one would use n=1 to
+avoid upsetting such broken devices.
+.TP
+.B "SCSI tape configuration"
+Some boot time configuration of the SCSI tape driver can be achieved
+by using the following:
+.IP
+.in +4n
+.EX
+.BI st= buf_size[,write_threshold[,max_bufs]]
+.EE
+.in
+.IP
+The first two numbers are specified in units of kB.
+The default
+.I buf_size
+is 32k\ B, and the maximum size that can be specified is a
+ridiculous 16384\ kB.
+The
+.I write_threshold
+is the value at which the buffer is committed to tape, with a
+default value of 30\ kB.
+The maximum number of buffers varies
+with the number of drives detected, and has a default of two.
+An example usage would be:
+.IP
+.in +4n
+.EX
+st=32,30,2
+.EE
+.in
+.IP
+Full details can be found in the file
+.I Documentation/scsi/st.txt
+(or
+.I drivers/scsi/README.st
+for older kernels) in the Linux kernel source.
+.SS Hard disks
+.TP
+.B "IDE Disk/CD-ROM Driver Parameters"
+The IDE driver accepts a number of parameters, which range from disk
+geometry specifications, to support for broken controller chips.
+Drive-specific options are specified by using 'hdX=' with X in 'a'\[en]'h'.
+.IP
+Non-drive-specific options are specified with the prefix 'hd='.
+Note that using a drive-specific prefix for a non-drive-specific option
+will still work, and the option will just be applied as expected.
+.IP
+Also note that 'hd=' can be used to refer to the next unspecified
+drive in the (a, ..., h) sequence.
+For the following discussions,
+the 'hd=' option will be cited for brevity.
+See the file
+.I Documentation/ide/ide.txt
+(or
+.I Documentation/ide.txt
+.\" Linux 2.0, 2.2, 2.4
+in older kernels, or
+.I drivers/block/README.ide
+in ancient kernels) in the Linux kernel source for more details.
+.TP
+.B "The 'hd=cyls,heads,sects[,wpcom[,irq]]' options"
+These options are used to specify the physical geometry of the disk.
+Only the first three values are required.
+The cylinder/head/sectors
+values will be those used by fdisk.
+The write precompensation value
+is ignored for IDE disks.
+The IRQ value specified will be the IRQ
+used for the interface that the drive resides on, and is not really a
+drive-specific parameter.
+.TP
+.B "The 'hd=serialize' option"
+The dual IDE interface CMD-640 chip is broken as designed such that
+when drives on the secondary interface are used at the same time as
+drives on the primary interface, it will corrupt your data.
+Using this
+option tells the driver to make sure that both interfaces are never
+used at the same time.
+.TP
+.B "The 'hd=noprobe' option"
+Do not probe for this drive.
+For example,
+.IP
+.in +4n
+.EX
+hdb=noprobe hdb=1166,7,17
+.EE
+.in
+.IP
+would disable the probe, but still specify the drive geometry so
+that it would be registered as a valid block device, and hence
+usable.
+.TP
+.B "The 'hd=nowerr' option"
+Some drives apparently have the
+.B WRERR_STAT
+bit stuck on permanently.
+This enables a work-around for these broken devices.
+.TP
+.B "The 'hd=cdrom' option"
+This tells the IDE driver that there is an ATAPI compatible CD-ROM
+attached in place of a normal IDE hard disk.
+In most cases the CD-ROM
+is identified automatically, but if it isn't then this may help.
+.TP
+.B "Standard ST-506 Disk Driver Options ('hd=')"
+The standard disk driver can accept geometry arguments for the disks
+similar to the IDE driver.
+Note however that it expects only three
+values (C/H/S); any more or any less and it will silently ignore you.
+Also, it accepts only 'hd=' as an argument, that is, 'hda='
+and so on are not valid here.
+The format is as follows:
+.IP
+.in +4n
+.EX
+hd=cyls,heads,sects
+.EE
+.in
+.IP
+If there are two disks installed, the above is repeated with the
+geometry parameters of the second disk.
+.SS Ethernet devices
+Different drivers make use of different parameters, but they all at
+least share having an IRQ, an I/O port base value, and a name.
+In its most generic form, it looks something like this:
+.P
+.in +4n
+.EX
+ether=irq,iobase[,param_1[,...param_8]],name
+.EE
+.in
+.P
+The first nonnumeric argument is taken as the name.
+The param_n values (if applicable) usually have different meanings for each
+different card/driver.
+Typical param_n values are used to specify
+things like shared memory address, interface selection, DMA channel
+and the like.
+.P
+The most common use of this parameter is to force probing for a second
+ethercard, as the default is to probe only for one.
+This can be accomplished with a simple:
+.P
+.in +4n
+.EX
+ether=0,0,eth1
+.EE
+.in
+.P
+Note that the values of zero for the IRQ and I/O base in the above
+example tell the driver(s) to autoprobe.
+.P
+The Ethernet-HowTo has extensive documentation on using multiple
+cards and on the card/driver-specific implementation
+of the param_n values where used.
+Interested readers should refer to
+the section in that document on their particular card.
+.SS The floppy disk driver
+There are many floppy driver options, and they are all listed in
+.I Documentation/blockdev/floppy.txt
+(or
+.I Documentation/floppy.txt
+in older kernels, or
+.I drivers/block/README.fd
+for ancient kernels) in the Linux kernel source.
+See that file for the details.
+.SS The sound driver
+The sound driver can also accept boot arguments to override the compiled-in
+values.
+This is not recommended, as it is rather complex.
+It is described in the Linux kernel source file
+.I Documentation/sound/oss/README.OSS
+.RI ( drivers/sound/Readme.linux
+in older kernel versions).
+It accepts
+a boot argument of the form:
+.P
+.in +4n
+.EX
+sound=device1[,device2[,device3...[,device10]]]
+.EE
+.in
+.P
+where each deviceN value is of the following format 0xTaaaId and the
+bytes are used as follows:
+.P
+T \- device type: 1=FM, 2=SB, 3=PAS, 4=GUS, 5=MPU401, 6=SB16,
+7=SB16-MPU401
+.P
+aaa \- I/O address in hex.
+.P
+I \- interrupt line in hex (i.e., 10=a, 11=b, ...)
+.P
+d \- DMA channel.
+.P
+As you can see, it gets pretty messy, and you are better off to compile
+in your own personal values as recommended.
+Using a boot argument of
+\&'sound=0' will disable the sound driver entirely.
+.SS The line printer driver
+.TP
+.B "'lp='"
+.br
+Syntax:
+.IP
+.in +4n
+.EX
+lp=0
+lp=auto
+lp=reset
+lp=port[,port...]
+.EE
+.in
+.IP
+You can tell the printer driver what ports to use and what ports not
+to use.
+The latter comes in handy if you don't want the printer driver
+to claim all available parallel ports, so that other drivers
+(e.g., PLIP, PPA) can use them instead.
+.IP
+The format of the argument is multiple port names.
+For example,
+lp=none,parport0 would use the first parallel port for lp1, and
+disable lp0.
+To disable the printer driver entirely, one can use
+lp=0.
+.\" .SH AUTHORS
+.\" Linus Torvalds (and many others)
+.SH SEE ALSO
+.BR klogd (8),
+.BR mount (8)
+.P
+For up-to-date information, see the kernel source file
+.IR Documentation/admin\-guide/kernel\-parameters.txt .
diff --git a/man/man7/bpf-helpers.7 b/man/man7/bpf-helpers.7
new file mode 100644
index 000000000..b4236f177
--- /dev/null
+++ b/man/man7/bpf-helpers.7
@@ -0,0 +1,5171 @@
+.\" Man page generated from reStructuredText.
+.
+.
+.nr rst2man-indent-level 0
+.
+.de1 rstReportMargin
+\\$1 \\n[an-margin]
+level \\n[rst2man-indent-level]
+level margin: \\n[rst2man-indent\\n[rst2man-indent-level]]
+-
+\\n[rst2man-indent0]
+\\n[rst2man-indent1]
+\\n[rst2man-indent2]
+..
+.de1 INDENT
+.\" .rstReportMargin pre:
+. RS \\$1
+. nr rst2man-indent\\n[rst2man-indent-level] \\n[an-margin]
+. nr rst2man-indent-level +1
+.\" .rstReportMargin post:
+..
+.de UNINDENT
+. RE
+.\" indent \\n[an-margin]
+.\" old: \\n[rst2man-indent\\n[rst2man-indent-level]]
+.nr rst2man-indent-level -1
+.\" new: \\n[rst2man-indent\\n[rst2man-indent-level]]
+.in \\n[rst2man-indent\\n[rst2man-indent-level]]u
+..
+.TH "BPF-HELPERS" 7 "2023-11-10" "Linux v6.8"
+.SH NAME
+BPF-HELPERS \- list of eBPF helper functions
+.\" Copyright (C) All BPF authors and contributors from 2014 to present.
+.
+.\" See git log include/uapi/linux/bpf.h in kernel tree for details.
+.
+.\" 
+.
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.
+.\" 
+.
+.\" Please do not edit this file. It was generated from the documentation
+.
+.\" located in file include/uapi/linux/bpf.h of the Linux kernel sources
+.
+.\" (helpers description), and from scripts/bpf_doc.py in the same
+.
+.\" repository (header and footer).
+.
+.SH DESCRIPTION
+.sp
+The extended Berkeley Packet Filter (eBPF) subsystem consists in programs
+written in a pseudo\-assembly language, then attached to one of the several
+kernel hooks and run in reaction of specific events. This framework differs
+from the older, \(dqclassic\(dq BPF (or \(dqcBPF\(dq) in several aspects, one of them being
+the ability to call special functions (or \(dqhelpers\(dq) from within a program.
+These functions are restricted to a white\-list of helpers defined in the
+kernel.
+.sp
+These helpers are used by eBPF programs to interact with the system, or with
+the context in which they work. For instance, they can be used to print
+debugging messages, to get the time since the system was booted, to interact
+with eBPF maps, or to manipulate network packets. Since there are several eBPF
+program types, and that they do not run in the same context, each program type
+can only call a subset of those helpers.
+.sp
+Due to eBPF conventions, a helper can not have more than five arguments.
+.sp
+Internally, eBPF programs call directly into the compiled helper functions
+without requiring any foreign\-function interface. As a result, calling helpers
+introduces no overhead, thus offering excellent performance.
+.sp
+This document is an attempt to list and document the helpers available to eBPF
+developers. They are sorted by chronological order (the oldest helpers in the
+kernel at the top).
+.SH HELPERS
+.INDENT 0.0
+.TP
+.B \fBvoid *bpf_map_lookup_elem(struct bpf_map *\fP\fImap\fP\fB, const void *\fP\fIkey\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Perform a lookup in \fImap\fP for an entry associated to \fIkey\fP\&.
+.TP
+.B Return
+Map value associated to \fIkey\fP, or \fBNULL\fP if no entry was
+found.
+.UNINDENT
+.TP
+.B \fBlong bpf_map_update_elem(struct bpf_map *\fP\fImap\fP\fB, const void *\fP\fIkey\fP\fB, const void *\fP\fIvalue\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Add or update the value of the entry associated to \fIkey\fP in
+\fImap\fP with \fIvalue\fP\&. \fIflags\fP is one of:
+.INDENT 7.0
+.TP
+.B \fBBPF_NOEXIST\fP
+The entry for \fIkey\fP must not exist in the map.
+.TP
+.B \fBBPF_EXIST\fP
+The entry for \fIkey\fP must already exist in the map.
+.TP
+.B \fBBPF_ANY\fP
+No condition on the existence of the entry for \fIkey\fP\&.
+.UNINDENT
+.sp
+Flag value \fBBPF_NOEXIST\fP cannot be used for maps of types
+\fBBPF_MAP_TYPE_ARRAY\fP or \fBBPF_MAP_TYPE_PERCPU_ARRAY\fP  (all
+elements always exist), the helper would return an error.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_map_delete_elem(struct bpf_map *\fP\fImap\fP\fB, const void *\fP\fIkey\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Delete entry with \fIkey\fP from \fImap\fP\&.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_probe_read(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIunsafe_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For tracing programs, safely attempt to read \fIsize\fP bytes from
+kernel space address \fIunsafe_ptr\fP and store the data in \fIdst\fP\&.
+.sp
+Generally, use \fBbpf_probe_read_user\fP() or
+\fBbpf_probe_read_kernel\fP() instead.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBu64 bpf_ktime_get_ns(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return the time elapsed since system boot, in nanoseconds.
+Does not include time the system was suspended.
+See: \fBclock_gettime\fP(\fBCLOCK_MONOTONIC\fP)
+.TP
+.B Return
+Current \fIktime\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_trace_printk(const char *\fP\fIfmt\fP\fB, u32\fP \fIfmt_size\fP\fB, ...)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is a \(dqprintk()\-like\(dq facility for debugging. It
+prints a message defined by format \fIfmt\fP (of size \fIfmt_size\fP)
+to file \fI/sys/kernel/tracing/trace\fP from TraceFS, if
+available. It can take up to three additional \fBu64\fP
+arguments (as an eBPF helpers, the total number of arguments is
+limited to five).
+.sp
+Each time the helper is called, it appends a line to the trace.
+Lines are discarded while \fI/sys/kernel/tracing/trace\fP is
+open, use \fI/sys/kernel/tracing/trace_pipe\fP to avoid this.
+The format of the trace is customizable, and the exact output
+one will get depends on the options set in
+\fI/sys/kernel/tracing/trace_options\fP (see also the
+\fIREADME\fP file under the same directory). However, it usually
+defaults to something like:
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+telnet\-470   [001] .N.. 419421.045894: 0x00000001: <formatted msg>
+.EE
+.UNINDENT
+.UNINDENT
+.sp
+In the above:
+.INDENT 7.0
+.INDENT 3.5
+.INDENT 0.0
+.IP \(bu 2
+\fBtelnet\fP is the name of the current task.
+.IP \(bu 2
+\fB470\fP is the PID of the current task.
+.IP \(bu 2
+\fB001\fP is the CPU number on which the task is
+running.
+.IP \(bu 2
+In \fB\&.N..\fP, each character refers to a set of
+options (whether irqs are enabled, scheduling
+options, whether hard/softirqs are running, level of
+preempt_disabled respectively). \fBN\fP means that
+\fBTIF_NEED_RESCHED\fP and \fBPREEMPT_NEED_RESCHED\fP
+are set.
+.IP \(bu 2
+\fB419421.045894\fP is a timestamp.
+.IP \(bu 2
+\fB0x00000001\fP is a fake value used by BPF for the
+instruction pointer register.
+.IP \(bu 2
+\fB<formatted msg>\fP is the message formatted with
+\fIfmt\fP\&.
+.UNINDENT
+.UNINDENT
+.UNINDENT
+.sp
+The conversion specifiers supported by \fIfmt\fP are similar, but
+more limited than for printk(). They are \fB%d\fP, \fB%i\fP,
+\fB%u\fP, \fB%x\fP, \fB%ld\fP, \fB%li\fP, \fB%lu\fP, \fB%lx\fP, \fB%lld\fP,
+\fB%lli\fP, \fB%llu\fP, \fB%llx\fP, \fB%p\fP, \fB%s\fP\&. No modifier (size
+of field, padding with zeroes, etc.) is available, and the
+helper will return \fB\-EINVAL\fP (but print nothing) if it
+encounters an unknown specifier.
+.sp
+Also, note that \fBbpf_trace_printk\fP() is slow, and should
+only be used for debugging purposes. For this reason, a notice
+block (spanning several lines) is printed to kernel logs and
+states that the helper should not be used \(dqfor production use\(dq
+the first time this helper is used (or more precisely, when
+\fBtrace_printk\fP() buffers are allocated). For passing values
+to user space, perf events should be preferred.
+.TP
+.B Return
+The number of bytes written to the buffer, or a negative error
+in case of failure.
+.UNINDENT
+.TP
+.B \fBu32 bpf_get_prandom_u32(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get a pseudo\-random number.
+.sp
+From a security point of view, this helper uses its own
+pseudo\-random internal state, and cannot be used to infer the
+seed of other random functions in the kernel. However, it is
+essential to note that the generator used by the helper is not
+cryptographically secure.
+.TP
+.B Return
+A random 32\-bit unsigned value.
+.UNINDENT
+.TP
+.B \fBu32 bpf_get_smp_processor_id(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the SMP (symmetric multiprocessing) processor id. Note that
+all programs run with migration disabled, which means that the
+SMP processor id is stable during all the execution of the
+program.
+.TP
+.B Return
+The SMP id of the processor running the program.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_store_bytes(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIoffset\fP\fB, const void *\fP\fIfrom\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Store \fIlen\fP bytes from address \fIfrom\fP into the packet
+associated to \fIskb\fP, at \fIoffset\fP\&. \fIflags\fP are a combination of
+\fBBPF_F_RECOMPUTE_CSUM\fP (automatically recompute the
+checksum for the packet after storing the bytes) and
+\fBBPF_F_INVALIDATE_HASH\fP (set \fIskb\fP\fB\->hash\fP, \fIskb\fP\fB\->swhash\fP and \fIskb\fP\fB\->l4hash\fP to 0).
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_l3_csum_replace(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIoffset\fP\fB, u64\fP \fIfrom\fP\fB, u64\fP \fIto\fP\fB, u64\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Recompute the layer 3 (e.g. IP) checksum for the packet
+associated to \fIskb\fP\&. Computation is incremental, so the helper
+must know the former value of the header field that was
+modified (\fIfrom\fP), the new value of this field (\fIto\fP), and the
+number of bytes (2 or 4) for this field, stored in \fIsize\fP\&.
+Alternatively, it is possible to store the difference between
+the previous and the new values of the header field in \fIto\fP, by
+setting \fIfrom\fP and \fIsize\fP to 0. For both methods, \fIoffset\fP
+indicates the location of the IP checksum within the packet.
+.sp
+This helper works in combination with \fBbpf_csum_diff\fP(),
+which does not update the checksum in\-place, but offers more
+flexibility and can handle sizes larger than 2 or 4 for the
+checksum to update.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_l4_csum_replace(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIoffset\fP\fB, u64\fP \fIfrom\fP\fB, u64\fP \fIto\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Recompute the layer 4 (e.g. TCP, UDP or ICMP) checksum for the
+packet associated to \fIskb\fP\&. Computation is incremental, so the
+helper must know the former value of the header field that was
+modified (\fIfrom\fP), the new value of this field (\fIto\fP), and the
+number of bytes (2 or 4) for this field, stored on the lowest
+four bits of \fIflags\fP\&. Alternatively, it is possible to store
+the difference between the previous and the new values of the
+header field in \fIto\fP, by setting \fIfrom\fP and the four lowest
+bits of \fIflags\fP to 0. For both methods, \fIoffset\fP indicates the
+location of the IP checksum within the packet. In addition to
+the size of the field, \fIflags\fP can be added (bitwise OR) actual
+flags. With \fBBPF_F_MARK_MANGLED_0\fP, a null checksum is left
+untouched (unless \fBBPF_F_MARK_ENFORCE\fP is added as well), and
+for updates resulting in a null checksum the value is set to
+\fBCSUM_MANGLED_0\fP instead. Flag \fBBPF_F_PSEUDO_HDR\fP indicates
+the checksum is to be computed against a pseudo\-header.
+.sp
+This helper works in combination with \fBbpf_csum_diff\fP(),
+which does not update the checksum in\-place, but offers more
+flexibility and can handle sizes larger than 2 or 4 for the
+checksum to update.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_tail_call(void *\fP\fIctx\fP\fB, struct bpf_map *\fP\fIprog_array_map\fP\fB, u32\fP \fIindex\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This special helper is used to trigger a \(dqtail call\(dq, or in
+other words, to jump into another eBPF program. The same stack
+frame is used (but values on stack and in registers for the
+caller are not accessible to the callee). This mechanism allows
+for program chaining, either for raising the maximum number of
+available eBPF instructions, or to execute given programs in
+conditional blocks. For security reasons, there is an upper
+limit to the number of successive tail calls that can be
+performed.
+.sp
+Upon call of this helper, the program attempts to jump into a
+program referenced at index \fIindex\fP in \fIprog_array_map\fP, a
+special map of type \fBBPF_MAP_TYPE_PROG_ARRAY\fP, and passes
+\fIctx\fP, a pointer to the context.
+.sp
+If the call succeeds, the kernel immediately runs the first
+instruction of the new program. This is not a function call,
+and it never returns to the previous program. If the call
+fails, then the helper has no effect, and the caller continues
+to run its subsequent instructions. A call can fail if the
+destination program for the jump does not exist (i.e. \fIindex\fP
+is superior to the number of entries in \fIprog_array_map\fP), or
+if the maximum number of tail calls has been reached for this
+chain of programs. This limit is defined in the kernel by the
+macro \fBMAX_TAIL_CALL_CNT\fP (not accessible to user space),
+which is currently set to 33.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_clone_redirect(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIifindex\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Clone and redirect the packet associated to \fIskb\fP to another
+net device of index \fIifindex\fP\&. Both ingress and egress
+interfaces can be used for redirection. The \fBBPF_F_INGRESS\fP
+value in \fIflags\fP is used to make the distinction (ingress path
+is selected if the flag is present, egress path otherwise).
+This is the only flag supported for now.
+.sp
+In comparison with \fBbpf_redirect\fP() helper,
+\fBbpf_clone_redirect\fP() has the associated cost of
+duplicating the packet buffer, but this can be executed out of
+the eBPF program. Conversely, \fBbpf_redirect\fP() is more
+efficient, but it is handled through an action code where the
+redirection happens only after the eBPF program has returned.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure. Positive
+error indicates a potential drop or congestion in the target
+device. The particular positive error codes are not defined.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_current_pid_tgid(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the current pid and tgid.
+.TP
+.B Return
+A 64\-bit integer containing the current tgid and pid, and
+created as such:
+\fIcurrent_task\fP\fB\->tgid << 32 |\fP
+\fIcurrent_task\fP\fB\->pid\fP\&.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_current_uid_gid(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the current uid and gid.
+.TP
+.B Return
+A 64\-bit integer containing the current GID and UID, and
+created as such: \fIcurrent_gid\fP \fB<< 32 |\fP \fIcurrent_uid\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_current_comm(void *\fP\fIbuf\fP\fB, u32\fP \fIsize_of_buf\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Copy the \fBcomm\fP attribute of the current task into \fIbuf\fP of
+\fIsize_of_buf\fP\&. The \fBcomm\fP attribute contains the name of
+the executable (excluding the path) for the current task. The
+\fIsize_of_buf\fP must be strictly positive. On success, the
+helper makes sure that the \fIbuf\fP is NUL\-terminated. On failure,
+it is filled with zeroes.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBu32 bpf_get_cgroup_classid(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Retrieve the classid for the current task, i.e. for the net_cls
+cgroup to which \fIskb\fP belongs.
+.sp
+This helper can be used on TC egress path, but not on ingress.
+.sp
+The net_cls cgroup provides an interface to tag network packets
+based on a user\-provided identifier for all traffic coming from
+the tasks belonging to the related cgroup. See also the related
+kernel documentation, available from the Linux sources in file
+\fIDocumentation/admin\-guide/cgroup\-v1/net_cls.rst\fP\&.
+.sp
+The Linux kernel has two versions for cgroups: there are
+cgroups v1 and cgroups v2. Both are available to users, who can
+use a mixture of them, but note that the net_cls cgroup is for
+cgroup v1 only. This makes it incompatible with BPF programs
+run on cgroups, which is a cgroup\-v2\-only feature (a socket can
+only hold data for one version of cgroups at a time).
+.sp
+This helper is only available is the kernel was compiled with
+the \fBCONFIG_CGROUP_NET_CLASSID\fP configuration option set to
+\(dq\fBy\fP\(dq or to \(dq\fBm\fP\(dq.
+.TP
+.B Return
+The classid, or 0 for the default unconfigured classid.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_vlan_push(struct sk_buff *\fP\fIskb\fP\fB, __be16\fP \fIvlan_proto\fP\fB, u16\fP \fIvlan_tci\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Push a \fIvlan_tci\fP (VLAN tag control information) of protocol
+\fIvlan_proto\fP to the packet associated to \fIskb\fP, then update
+the checksum. Note that if \fIvlan_proto\fP is different from
+\fBETH_P_8021Q\fP and \fBETH_P_8021AD\fP, it is considered to
+be \fBETH_P_8021Q\fP\&.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_vlan_pop(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Pop a VLAN header from the packet associated to \fIskb\fP\&.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_get_tunnel_key(struct sk_buff *\fP\fIskb\fP\fB, struct bpf_tunnel_key *\fP\fIkey\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get tunnel metadata. This helper takes a pointer \fIkey\fP to an
+empty \fBstruct bpf_tunnel_key\fP of \fBsize\fP, that will be
+filled with tunnel metadata for the packet associated to \fIskb\fP\&.
+The \fIflags\fP can be set to \fBBPF_F_TUNINFO_IPV6\fP, which
+indicates that the tunnel is based on IPv6 protocol instead of
+IPv4.
+.sp
+The \fBstruct bpf_tunnel_key\fP is an object that generalizes the
+principal parameters used by various tunneling protocols into a
+single struct. This way, it can be used to easily make a
+decision based on the contents of the encapsulation header,
+\(dqsummarized\(dq in this struct. In particular, it holds the IP
+address of the remote end (IPv4 or IPv6, depending on the case)
+in \fIkey\fP\fB\->remote_ipv4\fP or \fIkey\fP\fB\->remote_ipv6\fP\&. Also,
+this struct exposes the \fIkey\fP\fB\->tunnel_id\fP, which is
+generally mapped to a VNI (Virtual Network Identifier), making
+it programmable together with the \fBbpf_skb_set_tunnel_key\fP() helper.
+.sp
+Let\(aqs imagine that the following code is part of a program
+attached to the TC ingress interface, on one end of a GRE
+tunnel, and is supposed to filter out all messages coming from
+remote ends with IPv4 address other than 10.0.0.1:
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+int ret;
+struct bpf_tunnel_key key = {};
+
+ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
+if (ret < 0)
+        return TC_ACT_SHOT;     // drop packet
+
+if (key.remote_ipv4 != 0x0a000001)
+        return TC_ACT_SHOT;     // drop packet
+
+return TC_ACT_OK;               // accept packet
+.EE
+.UNINDENT
+.UNINDENT
+.sp
+This interface can also be used with all encapsulation devices
+that can operate in \(dqcollect metadata\(dq mode: instead of having
+one network device per specific configuration, the \(dqcollect
+metadata\(dq mode only requires a single device where the
+configuration can be extracted from this helper.
+.sp
+This can be used together with various tunnels such as VXLan,
+Geneve, GRE or IP in IP (IPIP).
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_set_tunnel_key(struct sk_buff *\fP\fIskb\fP\fB, struct bpf_tunnel_key *\fP\fIkey\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Populate tunnel metadata for packet associated to \fIskb.\fP The
+tunnel metadata is set to the contents of \fIkey\fP, of \fIsize\fP\&. The
+\fIflags\fP can be set to a combination of the following values:
+.INDENT 7.0
+.TP
+.B \fBBPF_F_TUNINFO_IPV6\fP
+Indicate that the tunnel is based on IPv6 protocol
+instead of IPv4.
+.TP
+.B \fBBPF_F_ZERO_CSUM_TX\fP
+For IPv4 packets, add a flag to tunnel metadata
+indicating that checksum computation should be skipped
+and checksum set to zeroes.
+.TP
+.B \fBBPF_F_DONT_FRAGMENT\fP
+Add a flag to tunnel metadata indicating that the
+packet should not be fragmented.
+.TP
+.B \fBBPF_F_SEQ_NUMBER\fP
+Add a flag to tunnel metadata indicating that a
+sequence number should be added to tunnel header before
+sending the packet. This flag was added for GRE
+encapsulation, but might be used with other protocols
+as well in the future.
+.TP
+.B \fBBPF_F_NO_TUNNEL_KEY\fP
+Add a flag to tunnel metadata indicating that no tunnel
+key should be set in the resulting tunnel header.
+.UNINDENT
+.sp
+Here is a typical usage on the transmit path:
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+struct bpf_tunnel_key key;
+     populate key ...
+bpf_skb_set_tunnel_key(skb, &key, sizeof(key), 0);
+bpf_clone_redirect(skb, vxlan_dev_ifindex, 0);
+.EE
+.UNINDENT
+.UNINDENT
+.sp
+See also the description of the \fBbpf_skb_get_tunnel_key\fP()
+helper for additional information.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBu64 bpf_perf_event_read(struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Read the value of a perf event counter. This helper relies on a
+\fImap\fP of type \fBBPF_MAP_TYPE_PERF_EVENT_ARRAY\fP\&. The nature of
+the perf event counter is selected when \fImap\fP is updated with
+perf event file descriptors. The \fImap\fP is an array whose size
+is the number of available CPUs, and each cell contains a value
+relative to one CPU. The value to retrieve is indicated by
+\fIflags\fP, that contains the index of the CPU to look up, masked
+with \fBBPF_F_INDEX_MASK\fP\&. Alternatively, \fIflags\fP can be set to
+\fBBPF_F_CURRENT_CPU\fP to indicate that the value for the
+current CPU should be retrieved.
+.sp
+Note that before Linux 4.13, only hardware perf event can be
+retrieved.
+.sp
+Also, be aware that the newer helper
+\fBbpf_perf_event_read_value\fP() is recommended over
+\fBbpf_perf_event_read\fP() in general. The latter has some ABI
+quirks where error and counter value are used as a return code
+(which is wrong to do since ranges may overlap). This issue is
+fixed with \fBbpf_perf_event_read_value\fP(), which at the same
+time provides more features over the \fBbpf_perf_event_read\fP() interface. Please refer to the description of
+\fBbpf_perf_event_read_value\fP() for details.
+.TP
+.B Return
+The value of the perf event counter read from the map, or a
+negative error code in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_redirect(u32\fP \fIifindex\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Redirect the packet to another net device of index \fIifindex\fP\&.
+This helper is somewhat similar to \fBbpf_clone_redirect\fP(), except that the packet is not cloned, which provides
+increased performance.
+.sp
+Except for XDP, both ingress and egress interfaces can be used
+for redirection. The \fBBPF_F_INGRESS\fP value in \fIflags\fP is used
+to make the distinction (ingress path is selected if the flag
+is present, egress path otherwise). Currently, XDP only
+supports redirection to the egress interface, and accepts no
+flag at all.
+.sp
+The same effect can also be attained with the more generic
+\fBbpf_redirect_map\fP(), which uses a BPF map to store the
+redirect target instead of providing it directly to the helper.
+.TP
+.B Return
+For XDP, the helper returns \fBXDP_REDIRECT\fP on success or
+\fBXDP_ABORTED\fP on error. For other program types, the values
+are \fBTC_ACT_REDIRECT\fP on success or \fBTC_ACT_SHOT\fP on
+error.
+.UNINDENT
+.TP
+.B \fBu32 bpf_get_route_realm(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Retrieve the realm or the route, that is to say the
+\fBtclassid\fP field of the destination for the \fIskb\fP\&. The
+identifier retrieved is a user\-provided tag, similar to the
+one used with the net_cls cgroup (see description for
+\fBbpf_get_cgroup_classid\fP() helper), but here this tag is
+held by a route (a destination entry), not by a task.
+.sp
+Retrieving this identifier works with the clsact TC egress hook
+(see also \fBtc\-bpf(8)\fP), or alternatively on conventional
+classful egress qdiscs, but not on TC ingress path. In case of
+clsact TC egress hook, this has the advantage that, internally,
+the destination entry has not been dropped yet in the transmit
+path. Therefore, the destination entry does not need to be
+artificially held via \fBnetif_keep_dst\fP() for a classful
+qdisc until the \fIskb\fP is freed.
+.sp
+This helper is available only if the kernel was compiled with
+\fBCONFIG_IP_ROUTE_CLASSID\fP configuration option.
+.TP
+.B Return
+The realm of the route for the packet associated to \fIskb\fP, or 0
+if none was found.
+.UNINDENT
+.TP
+.B \fBlong bpf_perf_event_output(void *\fP\fIctx\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB, void *\fP\fIdata\fP\fB, u64\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Write raw \fIdata\fP blob into a special BPF perf event held by
+\fImap\fP of type \fBBPF_MAP_TYPE_PERF_EVENT_ARRAY\fP\&. This perf
+event must have the following attributes: \fBPERF_SAMPLE_RAW\fP
+as \fBsample_type\fP, \fBPERF_TYPE_SOFTWARE\fP as \fBtype\fP, and
+\fBPERF_COUNT_SW_BPF_OUTPUT\fP as \fBconfig\fP\&.
+.sp
+The \fIflags\fP are used to indicate the index in \fImap\fP for which
+the value must be put, masked with \fBBPF_F_INDEX_MASK\fP\&.
+Alternatively, \fIflags\fP can be set to \fBBPF_F_CURRENT_CPU\fP
+to indicate that the index of the current CPU core should be
+used.
+.sp
+The value to write, of \fIsize\fP, is passed through eBPF stack and
+pointed by \fIdata\fP\&.
+.sp
+The context of the program \fIctx\fP needs also be passed to the
+helper.
+.sp
+On user space, a program willing to read the values needs to
+call \fBperf_event_open\fP() on the perf event (either for
+one or for all CPUs) and to store the file descriptor into the
+\fImap\fP\&. This must be done before the eBPF program can send data
+into it. An example is available in file
+\fIsamples/bpf/trace_output_user.c\fP in the Linux kernel source
+tree (the eBPF program counterpart is in
+\fIsamples/bpf/trace_output_kern.c\fP).
+.sp
+\fBbpf_perf_event_output\fP() achieves better performance
+than \fBbpf_trace_printk\fP() for sharing data with user
+space, and is much better suitable for streaming data from eBPF
+programs.
+.sp
+Note that this helper is not restricted to tracing use cases
+and can be used with programs attached to TC or XDP as well,
+where it allows for passing data to user space listeners. Data
+can be:
+.INDENT 7.0
+.IP \(bu 2
+Only custom structs,
+.IP \(bu 2
+Only the packet payload, or
+.IP \(bu 2
+A combination of both.
+.UNINDENT
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_load_bytes(const void *\fP\fIskb\fP\fB, u32\fP \fIoffset\fP\fB, void *\fP\fIto\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper was provided as an easy way to load data from a
+packet. It can be used to load \fIlen\fP bytes from \fIoffset\fP from
+the packet associated to \fIskb\fP, into the buffer pointed by
+\fIto\fP\&.
+.sp
+Since Linux 4.7, usage of this helper has mostly been replaced
+by \(dqdirect packet access\(dq, enabling packet data to be
+manipulated with \fIskb\fP\fB\->data\fP and \fIskb\fP\fB\->data_end\fP
+pointing respectively to the first byte of packet data and to
+the byte after the last byte of packet data. However, it
+remains useful if one wishes to read large quantities of data
+at once from a packet into the eBPF stack.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_stackid(void *\fP\fIctx\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Walk a user or a kernel stack and return its id. To achieve
+this, the helper needs \fIctx\fP, which is a pointer to the context
+on which the tracing program is executed, and a pointer to a
+\fImap\fP of type \fBBPF_MAP_TYPE_STACK_TRACE\fP\&.
+.sp
+The last argument, \fIflags\fP, holds the number of stack frames to
+skip (from 0 to 255), masked with
+\fBBPF_F_SKIP_FIELD_MASK\fP\&. The next bits can be used to set
+a combination of the following flags:
+.INDENT 7.0
+.TP
+.B \fBBPF_F_USER_STACK\fP
+Collect a user space stack instead of a kernel stack.
+.TP
+.B \fBBPF_F_FAST_STACK_CMP\fP
+Compare stacks by hash only.
+.TP
+.B \fBBPF_F_REUSE_STACKID\fP
+If two different stacks hash into the same \fIstackid\fP,
+discard the old one.
+.UNINDENT
+.sp
+The stack id retrieved is a 32 bit long integer handle which
+can be further combined with other data (including other stack
+ids) and used as a key into maps. This can be useful for
+generating a variety of graphs (such as flame graphs or off\-cpu
+graphs).
+.sp
+For walking a stack, this helper is an improvement over
+\fBbpf_probe_read\fP(), which can be used with unrolled loops
+but is not efficient and consumes a lot of eBPF instructions.
+Instead, \fBbpf_get_stackid\fP() can collect up to
+\fBPERF_MAX_STACK_DEPTH\fP both kernel and user frames. Note that
+this limit can be controlled with the \fBsysctl\fP program, and
+that it should be manually increased in order to profile long
+user stacks (such as stacks for Java programs). To do so, use:
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+# sysctl kernel.perf_event_max_stack=<new value>
+.EE
+.UNINDENT
+.UNINDENT
+.TP
+.B Return
+The positive or null stack id on success, or a negative error
+in case of failure.
+.UNINDENT
+.TP
+.B \fBs64 bpf_csum_diff(__be32 *\fP\fIfrom\fP\fB, u32\fP \fIfrom_size\fP\fB, __be32 *\fP\fIto\fP\fB, u32\fP \fIto_size\fP\fB, __wsum\fP \fIseed\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Compute a checksum difference, from the raw buffer pointed by
+\fIfrom\fP, of length \fIfrom_size\fP (that must be a multiple of 4),
+towards the raw buffer pointed by \fIto\fP, of size \fIto_size\fP
+(same remark). An optional \fIseed\fP can be added to the value
+(this can be cascaded, the seed may come from a previous call
+to the helper).
+.sp
+This is flexible enough to be used in several ways:
+.INDENT 7.0
+.IP \(bu 2
+With \fIfrom_size\fP == 0, \fIto_size\fP > 0 and \fIseed\fP set to
+checksum, it can be used when pushing new data.
+.IP \(bu 2
+With \fIfrom_size\fP > 0, \fIto_size\fP == 0 and \fIseed\fP set to
+checksum, it can be used when removing data from a packet.
+.IP \(bu 2
+With \fIfrom_size\fP > 0, \fIto_size\fP > 0 and \fIseed\fP set to 0, it
+can be used to compute a diff. Note that \fIfrom_size\fP and
+\fIto_size\fP do not need to be equal.
+.UNINDENT
+.sp
+This helper can be used in combination with
+\fBbpf_l3_csum_replace\fP() and \fBbpf_l4_csum_replace\fP(), to
+which one can feed in the difference computed with
+\fBbpf_csum_diff\fP().
+.TP
+.B Return
+The checksum result, or a negative error code in case of
+failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_get_tunnel_opt(struct sk_buff *\fP\fIskb\fP\fB, void *\fP\fIopt\fP\fB, u32\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Retrieve tunnel options metadata for the packet associated to
+\fIskb\fP, and store the raw tunnel option data to the buffer \fIopt\fP
+of \fIsize\fP\&.
+.sp
+This helper can be used with encapsulation devices that can
+operate in \(dqcollect metadata\(dq mode (please refer to the related
+note in the description of \fBbpf_skb_get_tunnel_key\fP() for
+more details). A particular example where this can be used is
+in combination with the Geneve encapsulation protocol, where it
+allows for pushing (with \fBbpf_skb_get_tunnel_opt\fP() helper)
+and retrieving arbitrary TLVs (Type\-Length\-Value headers) from
+the eBPF program. This allows for full customization of these
+headers.
+.TP
+.B Return
+The size of the option data retrieved.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_set_tunnel_opt(struct sk_buff *\fP\fIskb\fP\fB, void *\fP\fIopt\fP\fB, u32\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Set tunnel options metadata for the packet associated to \fIskb\fP
+to the option data contained in the raw buffer \fIopt\fP of \fIsize\fP\&.
+.sp
+See also the description of the \fBbpf_skb_get_tunnel_opt\fP()
+helper for additional information.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_change_proto(struct sk_buff *\fP\fIskb\fP\fB, __be16\fP \fIproto\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Change the protocol of the \fIskb\fP to \fIproto\fP\&. Currently
+supported are transition from IPv4 to IPv6, and from IPv6 to
+IPv4. The helper takes care of the groundwork for the
+transition, including resizing the socket buffer. The eBPF
+program is expected to fill the new headers, if any, via
+\fBskb_store_bytes\fP() and to recompute the checksums with
+\fBbpf_l3_csum_replace\fP() and \fBbpf_l4_csum_replace\fP(). The main case for this helper is to perform NAT64
+operations out of an eBPF program.
+.sp
+Internally, the GSO type is marked as dodgy so that headers are
+checked and segments are recalculated by the GSO/GRO engine.
+The size for GSO target is adapted as well.
+.sp
+All values for \fIflags\fP are reserved for future usage, and must
+be left at zero.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_change_type(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fItype\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Change the packet type for the packet associated to \fIskb\fP\&. This
+comes down to setting \fIskb\fP\fB\->pkt_type\fP to \fItype\fP, except
+the eBPF program does not have a write access to \fIskb\fP\fB\->pkt_type\fP beside this helper. Using a helper here allows
+for graceful handling of errors.
+.sp
+The major use case is to change incoming \fIskb*s to
+**PACKET_HOST*\fP in a programmatic way instead of having to
+recirculate via \fBredirect\fP(..., \fBBPF_F_INGRESS\fP), for
+example.
+.sp
+Note that \fItype\fP only allows certain values. At this time, they
+are:
+.INDENT 7.0
+.TP
+.B \fBPACKET_HOST\fP
+Packet is for us.
+.TP
+.B \fBPACKET_BROADCAST\fP
+Send packet to all.
+.TP
+.B \fBPACKET_MULTICAST\fP
+Send packet to group.
+.TP
+.B \fBPACKET_OTHERHOST\fP
+Send packet to someone else.
+.UNINDENT
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_under_cgroup(struct sk_buff *\fP\fIskb\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u32\fP \fIindex\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Check whether \fIskb\fP is a descendant of the cgroup2 held by
+\fImap\fP of type \fBBPF_MAP_TYPE_CGROUP_ARRAY\fP, at \fIindex\fP\&.
+.TP
+.B Return
+The return value depends on the result of the test, and can be:
+.INDENT 7.0
+.IP \(bu 2
+0, if the \fIskb\fP failed the cgroup2 descendant test.
+.IP \(bu 2
+1, if the \fIskb\fP succeeded the cgroup2 descendant test.
+.IP \(bu 2
+A negative error code, if an error occurred.
+.UNINDENT
+.UNINDENT
+.TP
+.B \fBu32 bpf_get_hash_recalc(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Retrieve the hash of the packet, \fIskb\fP\fB\->hash\fP\&. If it is
+not set, in particular if the hash was cleared due to mangling,
+recompute this hash. Later accesses to the hash can be done
+directly with \fIskb\fP\fB\->hash\fP\&.
+.sp
+Calling \fBbpf_set_hash_invalid\fP(), changing a packet
+prototype with \fBbpf_skb_change_proto\fP(), or calling
+\fBbpf_skb_store_bytes\fP() with the
+\fBBPF_F_INVALIDATE_HASH\fP are actions susceptible to clear
+the hash and to trigger a new computation for the next call to
+\fBbpf_get_hash_recalc\fP().
+.TP
+.B Return
+The 32\-bit hash.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_current_task(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the current task.
+.TP
+.B Return
+A pointer to the current task struct.
+.UNINDENT
+.TP
+.B \fBlong bpf_probe_write_user(void *\fP\fIdst\fP\fB, const void *\fP\fIsrc\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Attempt in a safe way to write \fIlen\fP bytes from the buffer
+\fIsrc\fP to \fIdst\fP in memory. It only works for threads that are in
+user context, and \fIdst\fP must be a valid user space address.
+.sp
+This helper should not be used to implement any kind of
+security mechanism because of TOC\-TOU attacks, but rather to
+debug, divert, and manipulate execution of semi\-cooperative
+processes.
+.sp
+Keep in mind that this feature is meant for experiments, and it
+has a risk of crashing the system and running programs.
+Therefore, when an eBPF program using this helper is attached,
+a warning including PID and process name is printed to kernel
+logs.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_current_task_under_cgroup(struct bpf_map *\fP\fImap\fP\fB, u32\fP \fIindex\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Check whether the probe is being run is the context of a given
+subset of the cgroup2 hierarchy. The cgroup2 to test is held by
+\fImap\fP of type \fBBPF_MAP_TYPE_CGROUP_ARRAY\fP, at \fIindex\fP\&.
+.TP
+.B Return
+The return value depends on the result of the test, and can be:
+.INDENT 7.0
+.IP \(bu 2
+1, if current task belongs to the cgroup2.
+.IP \(bu 2
+0, if current task does not belong to the cgroup2.
+.IP \(bu 2
+A negative error code, if an error occurred.
+.UNINDENT
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_change_tail(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Resize (trim or grow) the packet associated to \fIskb\fP to the
+new \fIlen\fP\&. The \fIflags\fP are reserved for future usage, and must
+be left at zero.
+.sp
+The basic idea is that the helper performs the needed work to
+change the size of the packet, then the eBPF program rewrites
+the rest via helpers like \fBbpf_skb_store_bytes\fP(),
+\fBbpf_l3_csum_replace\fP(), \fBbpf_l3_csum_replace\fP()
+and others. This helper is a slow path utility intended for
+replies with control messages. And because it is targeted for
+slow path, the helper itself can afford to be slow: it
+implicitly linearizes, unclones and drops offloads from the
+\fIskb\fP\&.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_pull_data(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Pull in non\-linear data in case the \fIskb\fP is non\-linear and not
+all of \fIlen\fP are part of the linear section. Make \fIlen\fP bytes
+from \fIskb\fP readable and writable. If a zero value is passed for
+\fIlen\fP, then all bytes in the linear part of \fIskb\fP will be made
+readable and writable.
+.sp
+This helper is only needed for reading and writing with direct
+packet access.
+.sp
+For direct packet access, testing that offsets to access
+are within packet boundaries (test on \fIskb\fP\fB\->data_end\fP) is
+susceptible to fail if offsets are invalid, or if the requested
+data is in non\-linear parts of the \fIskb\fP\&. On failure the
+program can just bail out, or in the case of a non\-linear
+buffer, use a helper to make the data available. The
+\fBbpf_skb_load_bytes\fP() helper is a first solution to access
+the data. Another one consists in using \fBbpf_skb_pull_data\fP
+to pull in once the non\-linear parts, then retesting and
+eventually access the data.
+.sp
+At the same time, this also makes sure the \fIskb\fP is uncloned,
+which is a necessary condition for direct write. As this needs
+to be an invariant for the write part only, the verifier
+detects writes and adds a prologue that is calling
+\fBbpf_skb_pull_data()\fP to effectively unclone the \fIskb\fP from
+the very beginning in case it is indeed cloned.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBs64 bpf_csum_update(struct sk_buff *\fP\fIskb\fP\fB, __wsum\fP \fIcsum\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Add the checksum \fIcsum\fP into \fIskb\fP\fB\->csum\fP in case the
+driver has supplied a checksum for the entire packet into that
+field. Return an error otherwise. This helper is intended to be
+used in combination with \fBbpf_csum_diff\fP(), in particular
+when the checksum needs to be updated after data has been
+written into the packet through direct packet access.
+.TP
+.B Return
+The checksum on success, or a negative error code in case of
+failure.
+.UNINDENT
+.TP
+.B \fBvoid bpf_set_hash_invalid(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Invalidate the current \fIskb\fP\fB\->hash\fP\&. It can be used after
+mangling on headers through direct packet access, in order to
+indicate that the hash is outdated and to trigger a
+recalculation the next time the kernel tries to access this
+hash or when the \fBbpf_get_hash_recalc\fP() helper is called.
+.TP
+.B Return
+void.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_numa_node_id(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return the id of the current NUMA node. The primary use case
+for this helper is the selection of sockets for the local NUMA
+node, when the program is attached to sockets using the
+\fBSO_ATTACH_REUSEPORT_EBPF\fP option (see also \fBsocket(7)\fP),
+but the helper is also available to other eBPF program types,
+similarly to \fBbpf_get_smp_processor_id\fP().
+.TP
+.B Return
+The id of current NUMA node.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_change_head(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Grows headroom of packet associated to \fIskb\fP and adjusts the
+offset of the MAC header accordingly, adding \fIlen\fP bytes of
+space. It automatically extends and reallocates memory as
+required.
+.sp
+This helper can be used on a layer 3 \fIskb\fP to push a MAC header
+for redirection into a layer 2 device.
+.sp
+All values for \fIflags\fP are reserved for future usage, and must
+be left at zero.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_xdp_adjust_head(struct xdp_buff *\fP\fIxdp_md\fP\fB, int\fP \fIdelta\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Adjust (move) \fIxdp_md\fP\fB\->data\fP by \fIdelta\fP bytes. Note that
+it is possible to use a negative value for \fIdelta\fP\&. This helper
+can be used to prepare the packet for pushing or popping
+headers.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_probe_read_str(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIunsafe_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Copy a NUL terminated string from an unsafe kernel address
+\fIunsafe_ptr\fP to \fIdst\fP\&. See \fBbpf_probe_read_kernel_str\fP() for
+more details.
+.sp
+Generally, use \fBbpf_probe_read_user_str\fP() or
+\fBbpf_probe_read_kernel_str\fP() instead.
+.TP
+.B Return
+On success, the strictly positive length of the string,
+including the trailing NUL character. On error, a negative
+value.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_socket_cookie(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+If the \fBstruct sk_buff\fP pointed by \fIskb\fP has a known socket,
+retrieve the cookie (generated by the kernel) of this socket.
+If no cookie has been set yet, generate a new cookie. Once
+generated, the socket cookie remains stable for the life of the
+socket. This helper can be useful for monitoring per socket
+networking traffic statistics as it provides a global socket
+identifier that can be assumed unique.
+.TP
+.B Return
+A 8\-byte long unique number on success, or 0 if the socket
+field is missing inside \fIskb\fP\&.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_socket_cookie(struct bpf_sock_addr *\fP\fIctx\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Equivalent to bpf_get_socket_cookie() helper that accepts
+\fIskb\fP, but gets socket from \fBstruct bpf_sock_addr\fP context.
+.TP
+.B Return
+A 8\-byte long unique number.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_socket_cookie(struct bpf_sock_ops *\fP\fIctx\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Equivalent to \fBbpf_get_socket_cookie\fP() helper that accepts
+\fIskb\fP, but gets socket from \fBstruct bpf_sock_ops\fP context.
+.TP
+.B Return
+A 8\-byte long unique number.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_socket_cookie(struct sock *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Equivalent to \fBbpf_get_socket_cookie\fP() helper that accepts
+\fIsk\fP, but gets socket from a BTF \fBstruct sock\fP\&. This helper
+also works for sleepable programs.
+.TP
+.B Return
+A 8\-byte long unique number or 0 if \fIsk\fP is NULL.
+.UNINDENT
+.TP
+.B \fBu32 bpf_get_socket_uid(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the owner UID of the socked associated to \fIskb\fP\&.
+.TP
+.B Return
+The owner UID of the socket associated to \fIskb\fP\&. If the socket
+is \fBNULL\fP, or if it is not a full socket (i.e. if it is a
+time\-wait or a request socket instead), \fBoverflowuid\fP value
+is returned (note that \fBoverflowuid\fP might also be the actual
+UID value for the socket).
+.UNINDENT
+.TP
+.B \fBlong bpf_set_hash(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIhash\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Set the full hash for \fIskb\fP (set the field \fIskb\fP\fB\->hash\fP)
+to value \fIhash\fP\&.
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBlong bpf_setsockopt(void *\fP\fIbpf_socket\fP\fB, int\fP \fIlevel\fP\fB, int\fP \fIoptname\fP\fB, void *\fP\fIoptval\fP\fB, int\fP \fIoptlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Emulate a call to \fBsetsockopt()\fP on the socket associated to
+\fIbpf_socket\fP, which must be a full socket. The \fIlevel\fP at
+which the option resides and the name \fIoptname\fP of the option
+must be specified, see \fBsetsockopt(2)\fP for more information.
+The option value of length \fIoptlen\fP is pointed by \fIoptval\fP\&.
+.sp
+\fIbpf_socket\fP should be one of the following:
+.INDENT 7.0
+.IP \(bu 2
+\fBstruct bpf_sock_ops\fP for \fBBPF_PROG_TYPE_SOCK_OPS\fP\&.
+.IP \(bu 2
+\fBstruct bpf_sock_addr\fP for \fBBPF_CGROUP_INET4_CONNECT\fP,
+\fBBPF_CGROUP_INET6_CONNECT\fP and \fBBPF_CGROUP_UNIX_CONNECT\fP\&.
+.UNINDENT
+.sp
+This helper actually implements a subset of \fBsetsockopt()\fP\&.
+It supports the following \fIlevel\fPs:
+.INDENT 7.0
+.IP \(bu 2
+\fBSOL_SOCKET\fP, which supports the following \fIoptname\fPs:
+\fBSO_RCVBUF\fP, \fBSO_SNDBUF\fP, \fBSO_MAX_PACING_RATE\fP,
+\fBSO_PRIORITY\fP, \fBSO_RCVLOWAT\fP, \fBSO_MARK\fP,
+\fBSO_BINDTODEVICE\fP, \fBSO_KEEPALIVE\fP, \fBSO_REUSEADDR\fP,
+\fBSO_REUSEPORT\fP, \fBSO_BINDTOIFINDEX\fP, \fBSO_TXREHASH\fP\&.
+.IP \(bu 2
+\fBIPPROTO_TCP\fP, which supports the following \fIoptname\fPs:
+\fBTCP_CONGESTION\fP, \fBTCP_BPF_IW\fP,
+\fBTCP_BPF_SNDCWND_CLAMP\fP, \fBTCP_SAVE_SYN\fP,
+\fBTCP_KEEPIDLE\fP, \fBTCP_KEEPINTVL\fP, \fBTCP_KEEPCNT\fP,
+\fBTCP_SYNCNT\fP, \fBTCP_USER_TIMEOUT\fP, \fBTCP_NOTSENT_LOWAT\fP,
+\fBTCP_NODELAY\fP, \fBTCP_MAXSEG\fP, \fBTCP_WINDOW_CLAMP\fP,
+\fBTCP_THIN_LINEAR_TIMEOUTS\fP, \fBTCP_BPF_DELACK_MAX\fP,
+\fBTCP_BPF_RTO_MIN\fP\&.
+.IP \(bu 2
+\fBIPPROTO_IP\fP, which supports \fIoptname\fP \fBIP_TOS\fP\&.
+.IP \(bu 2
+\fBIPPROTO_IPV6\fP, which supports the following \fIoptname\fPs:
+\fBIPV6_TCLASS\fP, \fBIPV6_AUTOFLOWLABEL\fP\&.
+.UNINDENT
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_adjust_room(struct sk_buff *\fP\fIskb\fP\fB, s32\fP \fIlen_diff\fP\fB, u32\fP \fImode\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Grow or shrink the room for data in the packet associated to
+\fIskb\fP by \fIlen_diff\fP, and according to the selected \fImode\fP\&.
+.sp
+By default, the helper will reset any offloaded checksum
+indicator of the skb to CHECKSUM_NONE. This can be avoided
+by the following flag:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_F_ADJ_ROOM_NO_CSUM_RESET\fP: Do not reset offloaded
+checksum data of the skb to CHECKSUM_NONE.
+.UNINDENT
+.sp
+There are two supported modes at this time:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_ADJ_ROOM_MAC\fP: Adjust room at the mac layer
+(room space is added or removed between the layer 2 and
+layer 3 headers).
+.IP \(bu 2
+\fBBPF_ADJ_ROOM_NET\fP: Adjust room at the network layer
+(room space is added or removed between the layer 3 and
+layer 4 headers).
+.UNINDENT
+.sp
+The following flags are supported at this time:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_F_ADJ_ROOM_FIXED_GSO\fP: Do not adjust gso_size.
+Adjusting mss in this way is not allowed for datagrams.
+.IP \(bu 2
+\fBBPF_F_ADJ_ROOM_ENCAP_L3_IPV4\fP,
+\fBBPF_F_ADJ_ROOM_ENCAP_L3_IPV6\fP:
+Any new space is reserved to hold a tunnel header.
+Configure skb offsets and other fields accordingly.
+.IP \(bu 2
+\fBBPF_F_ADJ_ROOM_ENCAP_L4_GRE\fP,
+\fBBPF_F_ADJ_ROOM_ENCAP_L4_UDP\fP:
+Use with ENCAP_L3 flags to further specify the tunnel type.
+.IP \(bu 2
+\fBBPF_F_ADJ_ROOM_ENCAP_L2\fP(\fIlen\fP):
+Use with ENCAP_L3/L4 flags to further specify the tunnel
+type; \fIlen\fP is the length of the inner MAC header.
+.IP \(bu 2
+\fBBPF_F_ADJ_ROOM_ENCAP_L2_ETH\fP:
+Use with BPF_F_ADJ_ROOM_ENCAP_L2 flag to further specify the
+L2 type as Ethernet.
+.IP \(bu 2
+\fBBPF_F_ADJ_ROOM_DECAP_L3_IPV4\fP,
+\fBBPF_F_ADJ_ROOM_DECAP_L3_IPV6\fP:
+Indicate the new IP header version after decapsulating the outer
+IP header. Used when the inner and outer IP versions are different.
+.UNINDENT
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_redirect_map(struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Redirect the packet to the endpoint referenced by \fImap\fP at
+index \fIkey\fP\&. Depending on its type, this \fImap\fP can contain
+references to net devices (for forwarding packets through other
+ports), or to CPUs (for redirecting XDP frames to another CPU;
+but this is only implemented for native XDP (with driver
+support) as of this writing).
+.sp
+The lower two bits of \fIflags\fP are used as the return code if
+the map lookup fails. This is so that the return value can be
+one of the XDP program return codes up to \fBXDP_TX\fP, as chosen
+by the caller. The higher bits of \fIflags\fP can be set to
+BPF_F_BROADCAST or BPF_F_EXCLUDE_INGRESS as defined below.
+.sp
+With BPF_F_BROADCAST the packet will be broadcasted to all the
+interfaces in the map, with BPF_F_EXCLUDE_INGRESS the ingress
+interface will be excluded when do broadcasting.
+.sp
+See also \fBbpf_redirect\fP(), which only supports redirecting
+to an ifindex, but doesn\(aqt require a map to do so.
+.TP
+.B Return
+\fBXDP_REDIRECT\fP on success, or the value of the two lower bits
+of the \fIflags\fP argument on error.
+.UNINDENT
+.TP
+.B \fBlong bpf_sk_redirect_map(struct sk_buff *\fP\fIskb\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u32\fP \fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Redirect the packet to the socket referenced by \fImap\fP (of type
+\fBBPF_MAP_TYPE_SOCKMAP\fP) at index \fIkey\fP\&. Both ingress and
+egress interfaces can be used for redirection. The
+\fBBPF_F_INGRESS\fP value in \fIflags\fP is used to make the
+distinction (ingress path is selected if the flag is present,
+egress path otherwise). This is the only flag supported for now.
+.TP
+.B Return
+\fBSK_PASS\fP on success, or \fBSK_DROP\fP on error.
+.UNINDENT
+.TP
+.B \fBlong bpf_sock_map_update(struct bpf_sock_ops *\fP\fIskops\fP\fB, struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Add an entry to, or update a \fImap\fP referencing sockets. The
+\fIskops\fP is used as a new value for the entry associated to
+\fIkey\fP\&. \fIflags\fP is one of:
+.INDENT 7.0
+.TP
+.B \fBBPF_NOEXIST\fP
+The entry for \fIkey\fP must not exist in the map.
+.TP
+.B \fBBPF_EXIST\fP
+The entry for \fIkey\fP must already exist in the map.
+.TP
+.B \fBBPF_ANY\fP
+No condition on the existence of the entry for \fIkey\fP\&.
+.UNINDENT
+.sp
+If the \fImap\fP has eBPF programs (parser and verdict), those will
+be inherited by the socket being added. If the socket is
+already attached to eBPF programs, this results in an error.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_xdp_adjust_meta(struct xdp_buff *\fP\fIxdp_md\fP\fB, int\fP \fIdelta\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Adjust the address pointed by \fIxdp_md\fP\fB\->data_meta\fP by
+\fIdelta\fP (which can be positive or negative). Note that this
+operation modifies the address stored in \fIxdp_md\fP\fB\->data\fP,
+so the latter must be loaded only after the helper has been
+called.
+.sp
+The use of \fIxdp_md\fP\fB\->data_meta\fP is optional and programs
+are not required to use it. The rationale is that when the
+packet is processed with XDP (e.g. as DoS filter), it is
+possible to push further meta data along with it before passing
+to the stack, and to give the guarantee that an ingress eBPF
+program attached as a TC classifier on the same device can pick
+this up for further post\-processing. Since TC works with socket
+buffers, it remains possible to set from XDP the \fBmark\fP or
+\fBpriority\fP pointers, or other pointers for the socket buffer.
+Having this scratch space generic and programmable allows for
+more flexibility as the user is free to store whatever meta
+data they need.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_perf_event_read_value(struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB, struct bpf_perf_event_value *\fP\fIbuf\fP\fB, u32\fP \fIbuf_size\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Read the value of a perf event counter, and store it into \fIbuf\fP
+of size \fIbuf_size\fP\&. This helper relies on a \fImap\fP of type
+\fBBPF_MAP_TYPE_PERF_EVENT_ARRAY\fP\&. The nature of the perf event
+counter is selected when \fImap\fP is updated with perf event file
+descriptors. The \fImap\fP is an array whose size is the number of
+available CPUs, and each cell contains a value relative to one
+CPU. The value to retrieve is indicated by \fIflags\fP, that
+contains the index of the CPU to look up, masked with
+\fBBPF_F_INDEX_MASK\fP\&. Alternatively, \fIflags\fP can be set to
+\fBBPF_F_CURRENT_CPU\fP to indicate that the value for the
+current CPU should be retrieved.
+.sp
+This helper behaves in a way close to
+\fBbpf_perf_event_read\fP() helper, save that instead of
+just returning the value observed, it fills the \fIbuf\fP
+structure. This allows for additional data to be retrieved: in
+particular, the enabled and running times (in \fIbuf\fP\fB\->enabled\fP and \fIbuf\fP\fB\->running\fP, respectively) are
+copied. In general, \fBbpf_perf_event_read_value\fP() is
+recommended over \fBbpf_perf_event_read\fP(), which has some
+ABI issues and provides fewer functionalities.
+.sp
+These values are interesting, because hardware PMU (Performance
+Monitoring Unit) counters are limited resources. When there are
+more PMU based perf events opened than available counters,
+kernel will multiplex these events so each event gets certain
+percentage (but not all) of the PMU time. In case that
+multiplexing happens, the number of samples or counter value
+will not reflect the case compared to when no multiplexing
+occurs. This makes comparison between different runs difficult.
+Typically, the counter value should be normalized before
+comparing to other experiments. The usual normalization is done
+as follows.
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+normalized_counter = counter * t_enabled / t_running
+.EE
+.UNINDENT
+.UNINDENT
+.sp
+Where t_enabled is the time enabled for event and t_running is
+the time running for event since last normalization. The
+enabled and running times are accumulated since the perf event
+open. To achieve scaling factor between two invocations of an
+eBPF program, users can use CPU id as the key (which is
+typical for perf array usage model) to remember the previous
+value and do the calculation inside the eBPF program.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_perf_prog_read_value(struct bpf_perf_event_data *\fP\fIctx\fP\fB, struct bpf_perf_event_value *\fP\fIbuf\fP\fB, u32\fP \fIbuf_size\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For an eBPF program attached to a perf event, retrieve the
+value of the event counter associated to \fIctx\fP and store it in
+the structure pointed by \fIbuf\fP and of size \fIbuf_size\fP\&. Enabled
+and running times are also stored in the structure (see
+description of helper \fBbpf_perf_event_read_value\fP() for
+more details).
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_getsockopt(void *\fP\fIbpf_socket\fP\fB, int\fP \fIlevel\fP\fB, int\fP \fIoptname\fP\fB, void *\fP\fIoptval\fP\fB, int\fP \fIoptlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Emulate a call to \fBgetsockopt()\fP on the socket associated to
+\fIbpf_socket\fP, which must be a full socket. The \fIlevel\fP at
+which the option resides and the name \fIoptname\fP of the option
+must be specified, see \fBgetsockopt(2)\fP for more information.
+The retrieved value is stored in the structure pointed by
+\fIopval\fP and of length \fIoptlen\fP\&.
+.sp
+\fIbpf_socket\fP should be one of the following:
+.INDENT 7.0
+.IP \(bu 2
+\fBstruct bpf_sock_ops\fP for \fBBPF_PROG_TYPE_SOCK_OPS\fP\&.
+.IP \(bu 2
+\fBstruct bpf_sock_addr\fP for \fBBPF_CGROUP_INET4_CONNECT\fP,
+\fBBPF_CGROUP_INET6_CONNECT\fP and \fBBPF_CGROUP_UNIX_CONNECT\fP\&.
+.UNINDENT
+.sp
+This helper actually implements a subset of \fBgetsockopt()\fP\&.
+It supports the same set of \fIoptname\fPs that is supported by
+the \fBbpf_setsockopt\fP() helper.  The exceptions are
+\fBTCP_BPF_*\fP is \fBbpf_setsockopt\fP() only and
+\fBTCP_SAVED_SYN\fP is \fBbpf_getsockopt\fP() only.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_override_return(struct pt_regs *\fP\fIregs\fP\fB, u64\fP \fIrc\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Used for error injection, this helper uses kprobes to override
+the return value of the probed function, and to set it to \fIrc\fP\&.
+The first argument is the context \fIregs\fP on which the kprobe
+works.
+.sp
+This helper works by setting the PC (program counter)
+to an override function which is run in place of the original
+probed function. This means the probed function is not run at
+all. The replacement function just returns with the required
+value.
+.sp
+This helper has security implications, and thus is subject to
+restrictions. It is only available if the kernel was compiled
+with the \fBCONFIG_BPF_KPROBE_OVERRIDE\fP configuration
+option, and in this case it only works on functions tagged with
+\fBALLOW_ERROR_INJECTION\fP in the kernel code.
+.sp
+Also, the helper is only available for the architectures having
+the CONFIG_FUNCTION_ERROR_INJECTION option. As of this writing,
+x86 architecture is the only one to support this feature.
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBlong bpf_sock_ops_cb_flags_set(struct bpf_sock_ops *\fP\fIbpf_sock\fP\fB, int\fP \fIargval\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Attempt to set the value of the \fBbpf_sock_ops_cb_flags\fP field
+for the full TCP socket associated to \fIbpf_sock_ops\fP to
+\fIargval\fP\&.
+.sp
+The primary use of this field is to determine if there should
+be calls to eBPF programs of type
+\fBBPF_PROG_TYPE_SOCK_OPS\fP at various points in the TCP
+code. A program of the same type can change its value, per
+connection and as necessary, when the connection is
+established. This field is directly accessible for reading, but
+this helper must be used for updates in order to return an
+error if an eBPF program tries to set a callback that is not
+supported in the current kernel.
+.sp
+\fIargval\fP is a flag array which can combine these flags:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_SOCK_OPS_RTO_CB_FLAG\fP (retransmission time out)
+.IP \(bu 2
+\fBBPF_SOCK_OPS_RETRANS_CB_FLAG\fP (retransmission)
+.IP \(bu 2
+\fBBPF_SOCK_OPS_STATE_CB_FLAG\fP (TCP state change)
+.IP \(bu 2
+\fBBPF_SOCK_OPS_RTT_CB_FLAG\fP (every RTT)
+.UNINDENT
+.sp
+Therefore, this function can be used to clear a callback flag by
+setting the appropriate bit to zero. e.g. to disable the RTO
+callback:
+.INDENT 7.0
+.TP
+.B \fBbpf_sock_ops_cb_flags_set(bpf_sock,\fP
+\fBbpf_sock\->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)\fP
+.UNINDENT
+.sp
+Here are some examples of where one could call such eBPF
+program:
+.INDENT 7.0
+.IP \(bu 2
+When RTO fires.
+.IP \(bu 2
+When a packet is retransmitted.
+.IP \(bu 2
+When the connection terminates.
+.IP \(bu 2
+When a packet is sent.
+.IP \(bu 2
+When a packet is received.
+.UNINDENT
+.TP
+.B Return
+Code \fB\-EINVAL\fP if the socket is not a full TCP socket;
+otherwise, a positive number containing the bits that could not
+be set is returned (which comes down to 0 if all bits were set
+as required).
+.UNINDENT
+.TP
+.B \fBlong bpf_msg_redirect_map(struct sk_msg_buff *\fP\fImsg\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u32\fP \fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is used in programs implementing policies at the
+socket level. If the message \fImsg\fP is allowed to pass (i.e. if
+the verdict eBPF program returns \fBSK_PASS\fP), redirect it to
+the socket referenced by \fImap\fP (of type
+\fBBPF_MAP_TYPE_SOCKMAP\fP) at index \fIkey\fP\&. Both ingress and
+egress interfaces can be used for redirection. The
+\fBBPF_F_INGRESS\fP value in \fIflags\fP is used to make the
+distinction (ingress path is selected if the flag is present,
+egress path otherwise). This is the only flag supported for now.
+.TP
+.B Return
+\fBSK_PASS\fP on success, or \fBSK_DROP\fP on error.
+.UNINDENT
+.TP
+.B \fBlong bpf_msg_apply_bytes(struct sk_msg_buff *\fP\fImsg\fP\fB, u32\fP \fIbytes\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For socket policies, apply the verdict of the eBPF program to
+the next \fIbytes\fP (number of bytes) of message \fImsg\fP\&.
+.sp
+For example, this helper can be used in the following cases:
+.INDENT 7.0
+.IP \(bu 2
+A single \fBsendmsg\fP() or \fBsendfile\fP() system call
+contains multiple logical messages that the eBPF program is
+supposed to read and for which it should apply a verdict.
+.IP \(bu 2
+An eBPF program only cares to read the first \fIbytes\fP of a
+\fImsg\fP\&. If the message has a large payload, then setting up
+and calling the eBPF program repeatedly for all bytes, even
+though the verdict is already known, would create unnecessary
+overhead.
+.UNINDENT
+.sp
+When called from within an eBPF program, the helper sets a
+counter internal to the BPF infrastructure, that is used to
+apply the last verdict to the next \fIbytes\fP\&. If \fIbytes\fP is
+smaller than the current data being processed from a
+\fBsendmsg\fP() or \fBsendfile\fP() system call, the first
+\fIbytes\fP will be sent and the eBPF program will be re\-run with
+the pointer for start of data pointing to byte number \fIbytes\fP
+\fB+ 1\fP\&. If \fIbytes\fP is larger than the current data being
+processed, then the eBPF verdict will be applied to multiple
+\fBsendmsg\fP() or \fBsendfile\fP() calls until \fIbytes\fP are
+consumed.
+.sp
+Note that if a socket closes with the internal counter holding
+a non\-zero value, this is not a problem because data is not
+being buffered for \fIbytes\fP and is sent as it is received.
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBlong bpf_msg_cork_bytes(struct sk_msg_buff *\fP\fImsg\fP\fB, u32\fP \fIbytes\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For socket policies, prevent the execution of the verdict eBPF
+program for message \fImsg\fP until \fIbytes\fP (byte number) have been
+accumulated.
+.sp
+This can be used when one needs a specific number of bytes
+before a verdict can be assigned, even if the data spans
+multiple \fBsendmsg\fP() or \fBsendfile\fP() calls. The extreme
+case would be a user calling \fBsendmsg\fP() repeatedly with
+1\-byte long message segments. Obviously, this is bad for
+performance, but it is still valid. If the eBPF program needs
+\fIbytes\fP bytes to validate a header, this helper can be used to
+prevent the eBPF program to be called again until \fIbytes\fP have
+been accumulated.
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBlong bpf_msg_pull_data(struct sk_msg_buff *\fP\fImsg\fP\fB, u32\fP \fIstart\fP\fB, u32\fP \fIend\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For socket policies, pull in non\-linear data from user space
+for \fImsg\fP and set pointers \fImsg\fP\fB\->data\fP and \fImsg\fP\fB\->data_end\fP to \fIstart\fP and \fIend\fP bytes offsets into \fImsg\fP,
+respectively.
+.sp
+If a program of type \fBBPF_PROG_TYPE_SK_MSG\fP is run on a
+\fImsg\fP it can only parse data that the (\fBdata\fP, \fBdata_end\fP)
+pointers have already consumed. For \fBsendmsg\fP() hooks this
+is likely the first scatterlist element. But for calls relying
+on the \fBsendpage\fP handler (e.g. \fBsendfile\fP()) this will
+be the range (\fB0\fP, \fB0\fP) because the data is shared with
+user space and by default the objective is to avoid allowing
+user space to modify data while (or after) eBPF verdict is
+being decided. This helper can be used to pull in data and to
+set the start and end pointer to given values. Data will be
+copied if necessary (i.e. if data was not linear and if start
+and end pointers do not point to the same chunk).
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.sp
+All values for \fIflags\fP are reserved for future usage, and must
+be left at zero.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_bind(struct bpf_sock_addr *\fP\fIctx\fP\fB, struct sockaddr *\fP\fIaddr\fP\fB, int\fP \fIaddr_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Bind the socket associated to \fIctx\fP to the address pointed by
+\fIaddr\fP, of length \fIaddr_len\fP\&. This allows for making outgoing
+connection from the desired IP address, which can be useful for
+example when all processes inside a cgroup should use one
+single IP address on a host that has multiple IP configured.
+.sp
+This helper works for IPv4 and IPv6, TCP and UDP sockets. The
+domain (\fIaddr\fP\fB\->sa_family\fP) must be \fBAF_INET\fP (or
+\fBAF_INET6\fP). It\(aqs advised to pass zero port (\fBsin_port\fP
+or \fBsin6_port\fP) which triggers IP_BIND_ADDRESS_NO_PORT\-like
+behavior and lets the kernel efficiently pick up an unused
+port as long as 4\-tuple is unique. Passing non\-zero port might
+lead to degraded performance.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_xdp_adjust_tail(struct xdp_buff *\fP\fIxdp_md\fP\fB, int\fP \fIdelta\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Adjust (move) \fIxdp_md\fP\fB\->data_end\fP by \fIdelta\fP bytes. It is
+possible to both shrink and grow the packet tail.
+Shrink done via \fIdelta\fP being a negative integer.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_get_xfrm_state(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIindex\fP\fB, struct bpf_xfrm_state *\fP\fIxfrm_state\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Retrieve the XFRM state (IP transform framework, see also
+\fBip\-xfrm(8)\fP) at \fIindex\fP in XFRM \(dqsecurity path\(dq for \fIskb\fP\&.
+.sp
+The retrieved value is stored in the \fBstruct bpf_xfrm_state\fP
+pointed by \fIxfrm_state\fP and of length \fIsize\fP\&.
+.sp
+All values for \fIflags\fP are reserved for future usage, and must
+be left at zero.
+.sp
+This helper is available only if the kernel was compiled with
+\fBCONFIG_XFRM\fP configuration option.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_stack(void *\fP\fIctx\fP\fB, void *\fP\fIbuf\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return a user or a kernel stack in bpf program provided buffer.
+To achieve this, the helper needs \fIctx\fP, which is a pointer
+to the context on which the tracing program is executed.
+To store the stacktrace, the bpf program provides \fIbuf\fP with
+a nonnegative \fIsize\fP\&.
+.sp
+The last argument, \fIflags\fP, holds the number of stack frames to
+skip (from 0 to 255), masked with
+\fBBPF_F_SKIP_FIELD_MASK\fP\&. The next bits can be used to set
+the following flags:
+.INDENT 7.0
+.TP
+.B \fBBPF_F_USER_STACK\fP
+Collect a user space stack instead of a kernel stack.
+.TP
+.B \fBBPF_F_USER_BUILD_ID\fP
+Collect (build_id, file_offset) instead of ips for user
+stack, only valid if \fBBPF_F_USER_STACK\fP is also
+specified.
+.sp
+\fIfile_offset\fP is an offset relative to the beginning
+of the executable or shared object file backing the vma
+which the \fIip\fP falls in. It is \fInot\fP an offset relative
+to that object\(aqs base address. Accordingly, it must be
+adjusted by adding (sh_addr \- sh_offset), where
+sh_{addr,offset} correspond to the executable section
+containing \fIfile_offset\fP in the object, for comparisons
+to symbols\(aq st_value to be valid.
+.UNINDENT
+.sp
+\fBbpf_get_stack\fP() can collect up to
+\fBPERF_MAX_STACK_DEPTH\fP both kernel and user frames, subject
+to sufficient large buffer size. Note that
+this limit can be controlled with the \fBsysctl\fP program, and
+that it should be manually increased in order to profile long
+user stacks (such as stacks for Java programs). To do so, use:
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+# sysctl kernel.perf_event_max_stack=<new value>
+.EE
+.UNINDENT
+.UNINDENT
+.TP
+.B Return
+The non\-negative copied \fIbuf\fP length equal to or less than
+\fIsize\fP on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_load_bytes_relative(const void *\fP\fIskb\fP\fB, u32\fP \fIoffset\fP\fB, void *\fP\fIto\fP\fB, u32\fP \fIlen\fP\fB, u32\fP \fIstart_header\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is similar to \fBbpf_skb_load_bytes\fP() in that
+it provides an easy way to load \fIlen\fP bytes from \fIoffset\fP
+from the packet associated to \fIskb\fP, into the buffer pointed
+by \fIto\fP\&. The difference to \fBbpf_skb_load_bytes\fP() is that
+a fifth argument \fIstart_header\fP exists in order to select a
+base offset to start from. \fIstart_header\fP can be one of:
+.INDENT 7.0
+.TP
+.B \fBBPF_HDR_START_MAC\fP
+Base offset to load data from is \fIskb\fP\(aqs mac header.
+.TP
+.B \fBBPF_HDR_START_NET\fP
+Base offset to load data from is \fIskb\fP\(aqs network header.
+.UNINDENT
+.sp
+In general, \(dqdirect packet access\(dq is the preferred method to
+access packet data, however, this helper is in particular useful
+in socket filters where \fIskb\fP\fB\->data\fP does not always point
+to the start of the mac header and where \(dqdirect packet access\(dq
+is not available.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_fib_lookup(void *\fP\fIctx\fP\fB, struct bpf_fib_lookup *\fP\fIparams\fP\fB, int\fP \fIplen\fP\fB, u32\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Do FIB lookup in kernel tables using parameters in \fIparams\fP\&.
+If lookup is successful and result shows packet is to be
+forwarded, the neighbor tables are searched for the nexthop.
+If successful (ie., FIB lookup shows forwarding and nexthop
+is resolved), the nexthop address is returned in ipv4_dst
+or ipv6_dst based on family, smac is set to mac address of
+egress device, dmac is set to nexthop mac address, rt_metric
+is set to metric from route (IPv4/IPv6 only), and ifindex
+is set to the device index of the nexthop from the FIB lookup.
+.sp
+\fIplen\fP argument is the size of the passed in struct.
+\fIflags\fP argument can be a combination of one or more of the
+following values:
+.INDENT 7.0
+.TP
+.B \fBBPF_FIB_LOOKUP_DIRECT\fP
+Do a direct table lookup vs full lookup using FIB
+rules.
+.TP
+.B \fBBPF_FIB_LOOKUP_TBID\fP
+Used with BPF_FIB_LOOKUP_DIRECT.
+Use the routing table ID present in \fIparams\fP\->tbid
+for the fib lookup.
+.TP
+.B \fBBPF_FIB_LOOKUP_OUTPUT\fP
+Perform lookup from an egress perspective (default is
+ingress).
+.TP
+.B \fBBPF_FIB_LOOKUP_SKIP_NEIGH\fP
+Skip the neighbour table lookup. \fIparams\fP\->dmac
+and \fIparams\fP\->smac will not be set as output. A common
+use case is to call \fBbpf_redirect_neigh\fP() after
+doing \fBbpf_fib_lookup\fP().
+.TP
+.B \fBBPF_FIB_LOOKUP_SRC\fP
+Derive and set source IP addr in \fIparams\fP\->ipv{4,6}_src
+for the nexthop. If the src addr cannot be derived,
+\fBBPF_FIB_LKUP_RET_NO_SRC_ADDR\fP is returned. In this
+case, \fIparams\fP\->dmac and \fIparams\fP\->smac are not set either.
+.UNINDENT
+.sp
+\fIctx\fP is either \fBstruct xdp_md\fP for XDP programs or
+\fBstruct sk_buff\fP tc cls_act programs.
+.TP
+.B Return
+.INDENT 7.0
+.IP \(bu 2
+< 0 if any input argument is invalid
+.IP \(bu 2
+0 on success (packet is forwarded, nexthop neighbor exists)
+.IP \(bu 2
+> 0 one of \fBBPF_FIB_LKUP_RET_\fP codes explaining why the
+packet is not forwarded or needs assist from full stack
+.UNINDENT
+.sp
+If lookup fails with BPF_FIB_LKUP_RET_FRAG_NEEDED, then the MTU
+was exceeded and output params\->mtu_result contains the MTU.
+.UNINDENT
+.TP
+.B \fBlong bpf_sock_hash_update(struct bpf_sock_ops *\fP\fIskops\fP\fB, struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Add an entry to, or update a sockhash \fImap\fP referencing sockets.
+The \fIskops\fP is used as a new value for the entry associated to
+\fIkey\fP\&. \fIflags\fP is one of:
+.INDENT 7.0
+.TP
+.B \fBBPF_NOEXIST\fP
+The entry for \fIkey\fP must not exist in the map.
+.TP
+.B \fBBPF_EXIST\fP
+The entry for \fIkey\fP must already exist in the map.
+.TP
+.B \fBBPF_ANY\fP
+No condition on the existence of the entry for \fIkey\fP\&.
+.UNINDENT
+.sp
+If the \fImap\fP has eBPF programs (parser and verdict), those will
+be inherited by the socket being added. If the socket is
+already attached to eBPF programs, this results in an error.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_msg_redirect_hash(struct sk_msg_buff *\fP\fImsg\fP\fB, struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is used in programs implementing policies at the
+socket level. If the message \fImsg\fP is allowed to pass (i.e. if
+the verdict eBPF program returns \fBSK_PASS\fP), redirect it to
+the socket referenced by \fImap\fP (of type
+\fBBPF_MAP_TYPE_SOCKHASH\fP) using hash \fIkey\fP\&. Both ingress and
+egress interfaces can be used for redirection. The
+\fBBPF_F_INGRESS\fP value in \fIflags\fP is used to make the
+distinction (ingress path is selected if the flag is present,
+egress path otherwise). This is the only flag supported for now.
+.TP
+.B Return
+\fBSK_PASS\fP on success, or \fBSK_DROP\fP on error.
+.UNINDENT
+.TP
+.B \fBlong bpf_sk_redirect_hash(struct sk_buff *\fP\fIskb\fP\fB, struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is used in programs implementing policies at the
+skb socket level. If the sk_buff \fIskb\fP is allowed to pass (i.e.
+if the verdict eBPF program returns \fBSK_PASS\fP), redirect it
+to the socket referenced by \fImap\fP (of type
+\fBBPF_MAP_TYPE_SOCKHASH\fP) using hash \fIkey\fP\&. Both ingress and
+egress interfaces can be used for redirection. The
+\fBBPF_F_INGRESS\fP value in \fIflags\fP is used to make the
+distinction (ingress path is selected if the flag is present,
+egress otherwise). This is the only flag supported for now.
+.TP
+.B Return
+\fBSK_PASS\fP on success, or \fBSK_DROP\fP on error.
+.UNINDENT
+.TP
+.B \fBlong bpf_lwt_push_encap(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fItype\fP\fB, void *\fP\fIhdr\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Encapsulate the packet associated to \fIskb\fP within a Layer 3
+protocol header. This header is provided in the buffer at
+address \fIhdr\fP, with \fIlen\fP its size in bytes. \fItype\fP indicates
+the protocol of the header and can be one of:
+.INDENT 7.0
+.TP
+.B \fBBPF_LWT_ENCAP_SEG6\fP
+IPv6 encapsulation with Segment Routing Header
+(\fBstruct ipv6_sr_hdr\fP). \fIhdr\fP only contains the SRH,
+the IPv6 header is computed by the kernel.
+.TP
+.B \fBBPF_LWT_ENCAP_SEG6_INLINE\fP
+Only works if \fIskb\fP contains an IPv6 packet. Insert a
+Segment Routing Header (\fBstruct ipv6_sr_hdr\fP) inside
+the IPv6 header.
+.TP
+.B \fBBPF_LWT_ENCAP_IP\fP
+IP encapsulation (GRE/GUE/IPIP/etc). The outer header
+must be IPv4 or IPv6, followed by zero or more
+additional headers, up to \fBLWT_BPF_MAX_HEADROOM\fP
+total bytes in all prepended headers. Please note that
+if \fBskb_is_gso\fP(\fIskb\fP) is true, no more than two
+headers can be prepended, and the inner header, if
+present, should be either GRE or UDP/GUE.
+.UNINDENT
+.sp
+\fBBPF_LWT_ENCAP_SEG6\fP* types can be called by BPF programs
+of type \fBBPF_PROG_TYPE_LWT_IN\fP; \fBBPF_LWT_ENCAP_IP\fP type can
+be called by bpf programs of types \fBBPF_PROG_TYPE_LWT_IN\fP and
+\fBBPF_PROG_TYPE_LWT_XMIT\fP\&.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_lwt_seg6_store_bytes(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIoffset\fP\fB, const void *\fP\fIfrom\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Store \fIlen\fP bytes from address \fIfrom\fP into the packet
+associated to \fIskb\fP, at \fIoffset\fP\&. Only the flags, tag and TLVs
+inside the outermost IPv6 Segment Routing Header can be
+modified through this helper.
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_lwt_seg6_adjust_srh(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIoffset\fP\fB, s32\fP \fIdelta\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Adjust the size allocated to TLVs in the outermost IPv6
+Segment Routing Header contained in the packet associated to
+\fIskb\fP, at position \fIoffset\fP by \fIdelta\fP bytes. Only offsets
+after the segments are accepted. \fIdelta\fP can be as well
+positive (growing) as negative (shrinking).
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_lwt_seg6_action(struct sk_buff *\fP\fIskb\fP\fB, u32\fP \fIaction\fP\fB, void *\fP\fIparam\fP\fB, u32\fP \fIparam_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Apply an IPv6 Segment Routing action of type \fIaction\fP to the
+packet associated to \fIskb\fP\&. Each action takes a parameter
+contained at address \fIparam\fP, and of length \fIparam_len\fP bytes.
+\fIaction\fP can be one of:
+.INDENT 7.0
+.TP
+.B \fBSEG6_LOCAL_ACTION_END_X\fP
+End.X action: Endpoint with Layer\-3 cross\-connect.
+Type of \fIparam\fP: \fBstruct in6_addr\fP\&.
+.TP
+.B \fBSEG6_LOCAL_ACTION_END_T\fP
+End.T action: Endpoint with specific IPv6 table lookup.
+Type of \fIparam\fP: \fBint\fP\&.
+.TP
+.B \fBSEG6_LOCAL_ACTION_END_B6\fP
+End.B6 action: Endpoint bound to an SRv6 policy.
+Type of \fIparam\fP: \fBstruct ipv6_sr_hdr\fP\&.
+.TP
+.B \fBSEG6_LOCAL_ACTION_END_B6_ENCAP\fP
+End.B6.Encap action: Endpoint bound to an SRv6
+encapsulation policy.
+Type of \fIparam\fP: \fBstruct ipv6_sr_hdr\fP\&.
+.UNINDENT
+.sp
+A call to this helper is susceptible to change the underlying
+packet buffer. Therefore, at load time, all checks on pointers
+previously done by the verifier are invalidated and must be
+performed again, if the helper is used in combination with
+direct packet access.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_rc_repeat(void *\fP\fIctx\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is used in programs implementing IR decoding, to
+report a successfully decoded repeat key message. This delays
+the generation of a key up event for previously generated
+key down event.
+.sp
+Some IR protocols like NEC have a special IR message for
+repeating last button, for when a button is held down.
+.sp
+The \fIctx\fP should point to the lirc sample as passed into
+the program.
+.sp
+This helper is only available is the kernel was compiled with
+the \fBCONFIG_BPF_LIRC_MODE2\fP configuration option set to
+\(dq\fBy\fP\(dq.
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBlong bpf_rc_keydown(void *\fP\fIctx\fP\fB, u32\fP \fIprotocol\fP\fB, u64\fP \fIscancode\fP\fB, u32\fP \fItoggle\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is used in programs implementing IR decoding, to
+report a successfully decoded key press with \fIscancode\fP,
+\fItoggle\fP value in the given \fIprotocol\fP\&. The scancode will be
+translated to a keycode using the rc keymap, and reported as
+an input key down event. After a period a key up event is
+generated. This period can be extended by calling either
+\fBbpf_rc_keydown\fP() again with the same values, or calling
+\fBbpf_rc_repeat\fP().
+.sp
+Some protocols include a toggle bit, in case the button was
+released and pressed again between consecutive scancodes.
+.sp
+The \fIctx\fP should point to the lirc sample as passed into
+the program.
+.sp
+The \fIprotocol\fP is the decoded protocol number (see
+\fBenum rc_proto\fP for some predefined values).
+.sp
+This helper is only available is the kernel was compiled with
+the \fBCONFIG_BPF_LIRC_MODE2\fP configuration option set to
+\(dq\fBy\fP\(dq.
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBu64 bpf_skb_cgroup_id(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return the cgroup v2 id of the socket associated with the \fIskb\fP\&.
+This is roughly similar to the \fBbpf_get_cgroup_classid\fP()
+helper for cgroup v1 by providing a tag resp. identifier that
+can be matched on or used for map lookups e.g. to implement
+policy. The cgroup v2 id of a given path in the hierarchy is
+exposed in user space through the f_handle API in order to get
+to the same 64\-bit id.
+.sp
+This helper can be used on TC egress path, but not on ingress,
+and is available only if the kernel was compiled with the
+\fBCONFIG_SOCK_CGROUP_DATA\fP configuration option.
+.TP
+.B Return
+The id is returned or 0 in case the id could not be retrieved.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_current_cgroup_id(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the current cgroup id based on the cgroup within which
+the current task is running.
+.TP
+.B Return
+A 64\-bit integer containing the current cgroup id based
+on the cgroup within which the current task is running.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_get_local_storage(void *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the pointer to the local storage area.
+The type and the size of the local storage is defined
+by the \fImap\fP argument.
+The \fIflags\fP meaning is specific for each map type,
+and has to be 0 for cgroup local storage.
+.sp
+Depending on the BPF program type, a local storage area
+can be shared between multiple instances of the BPF program,
+running simultaneously.
+.sp
+A user should care about the synchronization by himself.
+For example, by using the \fBBPF_ATOMIC\fP instructions to alter
+the shared data.
+.TP
+.B Return
+A pointer to the local storage area.
+.UNINDENT
+.TP
+.B \fBlong bpf_sk_select_reuseport(struct sk_reuseport_md *\fP\fIreuse\fP\fB, struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIkey\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Select a \fBSO_REUSEPORT\fP socket from a
+\fBBPF_MAP_TYPE_REUSEPORT_SOCKARRAY\fP \fImap\fP\&.
+It checks the selected socket is matching the incoming
+request in the socket buffer.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBu64 bpf_skb_ancestor_cgroup_id(struct sk_buff *\fP\fIskb\fP\fB, int\fP \fIancestor_level\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return id of cgroup v2 that is ancestor of cgroup associated
+with the \fIskb\fP at the \fIancestor_level\fP\&.  The root cgroup is at
+\fIancestor_level\fP zero and each step down the hierarchy
+increments the level. If \fIancestor_level\fP == level of cgroup
+associated with \fIskb\fP, then return value will be same as that
+of \fBbpf_skb_cgroup_id\fP().
+.sp
+The helper is useful to implement policies based on cgroups
+that are upper in hierarchy than immediate cgroup associated
+with \fIskb\fP\&.
+.sp
+The format of returned id and helper limitations are same as in
+\fBbpf_skb_cgroup_id\fP().
+.TP
+.B Return
+The id is returned or 0 in case the id could not be retrieved.
+.UNINDENT
+.TP
+.B \fBstruct bpf_sock *bpf_sk_lookup_tcp(void *\fP\fIctx\fP\fB, struct bpf_sock_tuple *\fP\fItuple\fP\fB, u32\fP \fItuple_size\fP\fB, u64\fP \fInetns\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Look for TCP socket matching \fItuple\fP, optionally in a child
+network namespace \fInetns\fP\&. The return value must be checked,
+and if non\-\fBNULL\fP, released via \fBbpf_sk_release\fP().
+.sp
+The \fIctx\fP should point to the context of the program, such as
+the skb or socket (depending on the hook in use). This is used
+to determine the base network namespace for the lookup.
+.sp
+\fItuple_size\fP must be one of:
+.INDENT 7.0
+.TP
+.B \fBsizeof\fP(\fItuple\fP\fB\->ipv4\fP)
+Look for an IPv4 socket.
+.TP
+.B \fBsizeof\fP(\fItuple\fP\fB\->ipv6\fP)
+Look for an IPv6 socket.
+.UNINDENT
+.sp
+If the \fInetns\fP is a negative signed 32\-bit integer, then the
+socket lookup table in the netns associated with the \fIctx\fP
+will be used. For the TC hooks, this is the netns of the device
+in the skb. For socket hooks, this is the netns of the socket.
+If \fInetns\fP is any other signed 32\-bit value greater than or
+equal to zero then it specifies the ID of the netns relative to
+the netns associated with the \fIctx\fP\&. \fInetns\fP values beyond the
+range of 32\-bit integers are reserved for future use.
+.sp
+All values for \fIflags\fP are reserved for future usage, and must
+be left at zero.
+.sp
+This helper is available only if the kernel was compiled with
+\fBCONFIG_NET\fP configuration option.
+.TP
+.B Return
+Pointer to \fBstruct bpf_sock\fP, or \fBNULL\fP in case of failure.
+For sockets with reuseport option, the \fBstruct bpf_sock\fP
+result is from \fIreuse\fP\fB\->socks\fP[] using the hash of the
+tuple.
+.UNINDENT
+.TP
+.B \fBstruct bpf_sock *bpf_sk_lookup_udp(void *\fP\fIctx\fP\fB, struct bpf_sock_tuple *\fP\fItuple\fP\fB, u32\fP \fItuple_size\fP\fB, u64\fP \fInetns\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Look for UDP socket matching \fItuple\fP, optionally in a child
+network namespace \fInetns\fP\&. The return value must be checked,
+and if non\-\fBNULL\fP, released via \fBbpf_sk_release\fP().
+.sp
+The \fIctx\fP should point to the context of the program, such as
+the skb or socket (depending on the hook in use). This is used
+to determine the base network namespace for the lookup.
+.sp
+\fItuple_size\fP must be one of:
+.INDENT 7.0
+.TP
+.B \fBsizeof\fP(\fItuple\fP\fB\->ipv4\fP)
+Look for an IPv4 socket.
+.TP
+.B \fBsizeof\fP(\fItuple\fP\fB\->ipv6\fP)
+Look for an IPv6 socket.
+.UNINDENT
+.sp
+If the \fInetns\fP is a negative signed 32\-bit integer, then the
+socket lookup table in the netns associated with the \fIctx\fP
+will be used. For the TC hooks, this is the netns of the device
+in the skb. For socket hooks, this is the netns of the socket.
+If \fInetns\fP is any other signed 32\-bit value greater than or
+equal to zero then it specifies the ID of the netns relative to
+the netns associated with the \fIctx\fP\&. \fInetns\fP values beyond the
+range of 32\-bit integers are reserved for future use.
+.sp
+All values for \fIflags\fP are reserved for future usage, and must
+be left at zero.
+.sp
+This helper is available only if the kernel was compiled with
+\fBCONFIG_NET\fP configuration option.
+.TP
+.B Return
+Pointer to \fBstruct bpf_sock\fP, or \fBNULL\fP in case of failure.
+For sockets with reuseport option, the \fBstruct bpf_sock\fP
+result is from \fIreuse\fP\fB\->socks\fP[] using the hash of the
+tuple.
+.UNINDENT
+.TP
+.B \fBlong bpf_sk_release(void *\fP\fIsock\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Release the reference held by \fIsock\fP\&. \fIsock\fP must be a
+non\-\fBNULL\fP pointer that was returned from
+\fBbpf_sk_lookup_xxx\fP().
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_map_push_elem(struct bpf_map *\fP\fImap\fP\fB, const void *\fP\fIvalue\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Push an element \fIvalue\fP in \fImap\fP\&. \fIflags\fP is one of:
+.INDENT 7.0
+.TP
+.B \fBBPF_EXIST\fP
+If the queue/stack is full, the oldest element is
+removed to make room for this.
+.UNINDENT
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_map_pop_elem(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIvalue\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Pop an element from \fImap\fP\&.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_map_peek_elem(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIvalue\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get an element from \fImap\fP without removing it.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_msg_push_data(struct sk_msg_buff *\fP\fImsg\fP\fB, u32\fP \fIstart\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For socket policies, insert \fIlen\fP bytes into \fImsg\fP at offset
+\fIstart\fP\&.
+.sp
+If a program of type \fBBPF_PROG_TYPE_SK_MSG\fP is run on a
+\fImsg\fP it may want to insert metadata or options into the \fImsg\fP\&.
+This can later be read and used by any of the lower layer BPF
+hooks.
+.sp
+This helper may fail if under memory pressure (a malloc
+fails) in these cases BPF programs will get an appropriate
+error and BPF programs will need to handle them.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_msg_pop_data(struct sk_msg_buff *\fP\fImsg\fP\fB, u32\fP \fIstart\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Will remove \fIlen\fP bytes from a \fImsg\fP starting at byte \fIstart\fP\&.
+This may result in \fBENOMEM\fP errors under certain situations if
+an allocation and copy are required due to a full ring buffer.
+However, the helper will try to avoid doing the allocation
+if possible. Other errors can occur if input parameters are
+invalid either due to \fIstart\fP byte not being valid part of \fImsg\fP
+payload and/or \fIpop\fP value being to large.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_rc_pointer_rel(void *\fP\fIctx\fP\fB, s32\fP \fIrel_x\fP\fB, s32\fP \fIrel_y\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is used in programs implementing IR decoding, to
+report a successfully decoded pointer movement.
+.sp
+The \fIctx\fP should point to the lirc sample as passed into
+the program.
+.sp
+This helper is only available is the kernel was compiled with
+the \fBCONFIG_BPF_LIRC_MODE2\fP configuration option set to
+\(dq\fBy\fP\(dq.
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBlong bpf_spin_lock(struct bpf_spin_lock *\fP\fIlock\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Acquire a spinlock represented by the pointer \fIlock\fP, which is
+stored as part of a value of a map. Taking the lock allows to
+safely update the rest of the fields in that value. The
+spinlock can (and must) later be released with a call to
+\fBbpf_spin_unlock\fP(\fIlock\fP).
+.sp
+Spinlocks in BPF programs come with a number of restrictions
+and constraints:
+.INDENT 7.0
+.IP \(bu 2
+\fBbpf_spin_lock\fP objects are only allowed inside maps of
+types \fBBPF_MAP_TYPE_HASH\fP and \fBBPF_MAP_TYPE_ARRAY\fP (this
+list could be extended in the future).
+.IP \(bu 2
+BTF description of the map is mandatory.
+.IP \(bu 2
+The BPF program can take ONE lock at a time, since taking two
+or more could cause dead locks.
+.IP \(bu 2
+Only one \fBstruct bpf_spin_lock\fP is allowed per map element.
+.IP \(bu 2
+When the lock is taken, calls (either BPF to BPF or helpers)
+are not allowed.
+.IP \(bu 2
+The \fBBPF_LD_ABS\fP and \fBBPF_LD_IND\fP instructions are not
+allowed inside a spinlock\-ed region.
+.IP \(bu 2
+The BPF program MUST call \fBbpf_spin_unlock\fP() to release
+the lock, on all execution paths, before it returns.
+.IP \(bu 2
+The BPF program can access \fBstruct bpf_spin_lock\fP only via
+the \fBbpf_spin_lock\fP() and \fBbpf_spin_unlock\fP()
+helpers. Loading or storing data into the \fBstruct
+bpf_spin_lock\fP \fIlock\fP\fB;\fP field of a map is not allowed.
+.IP \(bu 2
+To use the \fBbpf_spin_lock\fP() helper, the BTF description
+of the map value must be a struct and have \fBstruct
+bpf_spin_lock\fP \fIanyname\fP\fB;\fP field at the top level.
+Nested lock inside another struct is not allowed.
+.IP \(bu 2
+The \fBstruct bpf_spin_lock\fP \fIlock\fP field in a map value must
+be aligned on a multiple of 4 bytes in that value.
+.IP \(bu 2
+Syscall with command \fBBPF_MAP_LOOKUP_ELEM\fP does not copy
+the \fBbpf_spin_lock\fP field to user space.
+.IP \(bu 2
+Syscall with command \fBBPF_MAP_UPDATE_ELEM\fP, or update from
+a BPF program, do not update the \fBbpf_spin_lock\fP field.
+.IP \(bu 2
+\fBbpf_spin_lock\fP cannot be on the stack or inside a
+networking packet (it can only be inside of a map values).
+.IP \(bu 2
+\fBbpf_spin_lock\fP is available to root only.
+.IP \(bu 2
+Tracing programs and socket filter programs cannot use
+\fBbpf_spin_lock\fP() due to insufficient preemption checks
+(but this may change in the future).
+.IP \(bu 2
+\fBbpf_spin_lock\fP is not allowed in inner maps of map\-in\-map.
+.UNINDENT
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBlong bpf_spin_unlock(struct bpf_spin_lock *\fP\fIlock\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Release the \fIlock\fP previously locked by a call to
+\fBbpf_spin_lock\fP(\fIlock\fP).
+.TP
+.B Return
+0
+.UNINDENT
+.TP
+.B \fBstruct bpf_sock *bpf_sk_fullsock(struct bpf_sock *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper gets a \fBstruct bpf_sock\fP pointer such
+that all the fields in this \fBbpf_sock\fP can be accessed.
+.TP
+.B Return
+A \fBstruct bpf_sock\fP pointer on success, or \fBNULL\fP in
+case of failure.
+.UNINDENT
+.TP
+.B \fBstruct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper gets a \fBstruct bpf_tcp_sock\fP pointer from a
+\fBstruct bpf_sock\fP pointer.
+.TP
+.B Return
+A \fBstruct bpf_tcp_sock\fP pointer on success, or \fBNULL\fP in
+case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_ecn_set_ce(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Set ECN (Explicit Congestion Notification) field of IP header
+to \fBCE\fP (Congestion Encountered) if current value is \fBECT\fP
+(ECN Capable Transport). Otherwise, do nothing. Works with IPv6
+and IPv4.
+.TP
+.B Return
+1 if the \fBCE\fP flag is set (either by the current helper call
+or because it was already present), 0 if it is not set.
+.UNINDENT
+.TP
+.B \fBstruct bpf_sock *bpf_get_listener_sock(struct bpf_sock *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return a \fBstruct bpf_sock\fP pointer in \fBTCP_LISTEN\fP state.
+\fBbpf_sk_release\fP() is unnecessary and not allowed.
+.TP
+.B Return
+A \fBstruct bpf_sock\fP pointer on success, or \fBNULL\fP in
+case of failure.
+.UNINDENT
+.TP
+.B \fBstruct bpf_sock *bpf_skc_lookup_tcp(void *\fP\fIctx\fP\fB, struct bpf_sock_tuple *\fP\fItuple\fP\fB, u32\fP \fItuple_size\fP\fB, u64\fP \fInetns\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Look for TCP socket matching \fItuple\fP, optionally in a child
+network namespace \fInetns\fP\&. The return value must be checked,
+and if non\-\fBNULL\fP, released via \fBbpf_sk_release\fP().
+.sp
+This function is identical to \fBbpf_sk_lookup_tcp\fP(), except
+that it also returns timewait or request sockets. Use
+\fBbpf_sk_fullsock\fP() or \fBbpf_tcp_sock\fP() to access the
+full structure.
+.sp
+This helper is available only if the kernel was compiled with
+\fBCONFIG_NET\fP configuration option.
+.TP
+.B Return
+Pointer to \fBstruct bpf_sock\fP, or \fBNULL\fP in case of failure.
+For sockets with reuseport option, the \fBstruct bpf_sock\fP
+result is from \fIreuse\fP\fB\->socks\fP[] using the hash of the
+tuple.
+.UNINDENT
+.TP
+.B \fBlong bpf_tcp_check_syncookie(void *\fP\fIsk\fP\fB, void *\fP\fIiph\fP\fB, u32\fP \fIiph_len\fP\fB, struct tcphdr *\fP\fIth\fP\fB, u32\fP \fIth_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Check whether \fIiph\fP and \fIth\fP contain a valid SYN cookie ACK for
+the listening socket in \fIsk\fP\&.
+.sp
+\fIiph\fP points to the start of the IPv4 or IPv6 header, while
+\fIiph_len\fP contains \fBsizeof\fP(\fBstruct iphdr\fP) or
+\fBsizeof\fP(\fBstruct ipv6hdr\fP).
+.sp
+\fIth\fP points to the start of the TCP header, while \fIth_len\fP
+contains the length of the TCP header (at least
+\fBsizeof\fP(\fBstruct tcphdr\fP)).
+.TP
+.B Return
+0 if \fIiph\fP and \fIth\fP are a valid SYN cookie ACK, or a negative
+error otherwise.
+.UNINDENT
+.TP
+.B \fBlong bpf_sysctl_get_name(struct bpf_sysctl *\fP\fIctx\fP\fB, char *\fP\fIbuf\fP\fB, size_t\fP \fIbuf_len\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get name of sysctl in /proc/sys/ and copy it into provided by
+program buffer \fIbuf\fP of size \fIbuf_len\fP\&.
+.sp
+The buffer is always NUL terminated, unless it\(aqs zero\-sized.
+.sp
+If \fIflags\fP is zero, full name (e.g. \(dqnet/ipv4/tcp_mem\(dq) is
+copied. Use \fBBPF_F_SYSCTL_BASE_NAME\fP flag to copy base name
+only (e.g. \(dqtcp_mem\(dq).
+.TP
+.B Return
+Number of character copied (not including the trailing NUL).
+.sp
+\fB\-E2BIG\fP if the buffer wasn\(aqt big enough (\fIbuf\fP will contain
+truncated name in this case).
+.UNINDENT
+.TP
+.B \fBlong bpf_sysctl_get_current_value(struct bpf_sysctl *\fP\fIctx\fP\fB, char *\fP\fIbuf\fP\fB, size_t\fP \fIbuf_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get current value of sysctl as it is presented in /proc/sys
+(incl. newline, etc), and copy it as a string into provided
+by program buffer \fIbuf\fP of size \fIbuf_len\fP\&.
+.sp
+The whole value is copied, no matter what file position user
+space issued e.g. sys_read at.
+.sp
+The buffer is always NUL terminated, unless it\(aqs zero\-sized.
+.TP
+.B Return
+Number of character copied (not including the trailing NUL).
+.sp
+\fB\-E2BIG\fP if the buffer wasn\(aqt big enough (\fIbuf\fP will contain
+truncated name in this case).
+.sp
+\fB\-EINVAL\fP if current value was unavailable, e.g. because
+sysctl is uninitialized and read returns \-EIO for it.
+.UNINDENT
+.TP
+.B \fBlong bpf_sysctl_get_new_value(struct bpf_sysctl *\fP\fIctx\fP\fB, char *\fP\fIbuf\fP\fB, size_t\fP \fIbuf_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get new value being written by user space to sysctl (before
+the actual write happens) and copy it as a string into
+provided by program buffer \fIbuf\fP of size \fIbuf_len\fP\&.
+.sp
+User space may write new value at file position > 0.
+.sp
+The buffer is always NUL terminated, unless it\(aqs zero\-sized.
+.TP
+.B Return
+Number of character copied (not including the trailing NUL).
+.sp
+\fB\-E2BIG\fP if the buffer wasn\(aqt big enough (\fIbuf\fP will contain
+truncated name in this case).
+.sp
+\fB\-EINVAL\fP if sysctl is being read.
+.UNINDENT
+.TP
+.B \fBlong bpf_sysctl_set_new_value(struct bpf_sysctl *\fP\fIctx\fP\fB, const char *\fP\fIbuf\fP\fB, size_t\fP \fIbuf_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Override new value being written by user space to sysctl with
+value provided by program in buffer \fIbuf\fP of size \fIbuf_len\fP\&.
+.sp
+\fIbuf\fP should contain a string in same form as provided by user
+space on sysctl write.
+.sp
+User space may write new value at file position > 0. To override
+the whole sysctl value file position should be set to zero.
+.TP
+.B Return
+0 on success.
+.sp
+\fB\-E2BIG\fP if the \fIbuf_len\fP is too big.
+.sp
+\fB\-EINVAL\fP if sysctl is being read.
+.UNINDENT
+.TP
+.B \fBlong bpf_strtol(const char *\fP\fIbuf\fP\fB, size_t\fP \fIbuf_len\fP\fB, u64\fP \fIflags\fP\fB, long *\fP\fIres\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Convert the initial part of the string from buffer \fIbuf\fP of
+size \fIbuf_len\fP to a long integer according to the given base
+and save the result in \fIres\fP\&.
+.sp
+The string may begin with an arbitrary amount of white space
+(as determined by \fBisspace\fP(3)) followed by a single
+optional \(aq\fB\-\fP\(aq sign.
+.sp
+Five least significant bits of \fIflags\fP encode base, other bits
+are currently unused.
+.sp
+Base must be either 8, 10, 16 or 0 to detect it automatically
+similar to user space \fBstrtol\fP(3).
+.TP
+.B Return
+Number of characters consumed on success. Must be positive but
+no more than \fIbuf_len\fP\&.
+.sp
+\fB\-EINVAL\fP if no valid digits were found or unsupported base
+was provided.
+.sp
+\fB\-ERANGE\fP if resulting value was out of range.
+.UNINDENT
+.TP
+.B \fBlong bpf_strtoul(const char *\fP\fIbuf\fP\fB, size_t\fP \fIbuf_len\fP\fB, u64\fP \fIflags\fP\fB, unsigned long *\fP\fIres\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Convert the initial part of the string from buffer \fIbuf\fP of
+size \fIbuf_len\fP to an unsigned long integer according to the
+given base and save the result in \fIres\fP\&.
+.sp
+The string may begin with an arbitrary amount of white space
+(as determined by \fBisspace\fP(3)).
+.sp
+Five least significant bits of \fIflags\fP encode base, other bits
+are currently unused.
+.sp
+Base must be either 8, 10, 16 or 0 to detect it automatically
+similar to user space \fBstrtoul\fP(3).
+.TP
+.B Return
+Number of characters consumed on success. Must be positive but
+no more than \fIbuf_len\fP\&.
+.sp
+\fB\-EINVAL\fP if no valid digits were found or unsupported base
+was provided.
+.sp
+\fB\-ERANGE\fP if resulting value was out of range.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_sk_storage_get(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIsk\fP\fB, void *\fP\fIvalue\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get a bpf\-local\-storage from a \fIsk\fP\&.
+.sp
+Logically, it could be thought of getting the value from
+a \fImap\fP with \fIsk\fP as the \fBkey\fP\&.  From this
+perspective,  the usage is not much different from
+\fBbpf_map_lookup_elem\fP(\fImap\fP, \fB&\fP\fIsk\fP) except this
+helper enforces the key must be a full socket and the map must
+be a \fBBPF_MAP_TYPE_SK_STORAGE\fP also.
+.sp
+Underneath, the value is stored locally at \fIsk\fP instead of
+the \fImap\fP\&.  The \fImap\fP is used as the bpf\-local\-storage
+\(dqtype\(dq. The bpf\-local\-storage \(dqtype\(dq (i.e. the \fImap\fP) is
+searched against all bpf\-local\-storages residing at \fIsk\fP\&.
+.sp
+\fIsk\fP is a kernel \fBstruct sock\fP pointer for LSM program.
+\fIsk\fP is a \fBstruct bpf_sock\fP pointer for other program types.
+.sp
+An optional \fIflags\fP (\fBBPF_SK_STORAGE_GET_F_CREATE\fP) can be
+used such that a new bpf\-local\-storage will be
+created if one does not exist.  \fIvalue\fP can be used
+together with \fBBPF_SK_STORAGE_GET_F_CREATE\fP to specify
+the initial value of a bpf\-local\-storage.  If \fIvalue\fP is
+\fBNULL\fP, the new bpf\-local\-storage will be zero initialized.
+.TP
+.B Return
+A bpf\-local\-storage pointer is returned on success.
+.sp
+\fBNULL\fP if not found or there was an error in adding
+a new bpf\-local\-storage.
+.UNINDENT
+.TP
+.B \fBlong bpf_sk_storage_delete(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Delete a bpf\-local\-storage from a \fIsk\fP\&.
+.TP
+.B Return
+0 on success.
+.sp
+\fB\-ENOENT\fP if the bpf\-local\-storage cannot be found.
+\fB\-EINVAL\fP if sk is not a fullsock (e.g. a request_sock).
+.UNINDENT
+.TP
+.B \fBlong bpf_send_signal(u32\fP \fIsig\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Send signal \fIsig\fP to the process of the current task.
+The signal may be delivered to any of this process\(aqs threads.
+.TP
+.B Return
+0 on success or successfully queued.
+.sp
+\fB\-EBUSY\fP if work queue under nmi is full.
+.sp
+\fB\-EINVAL\fP if \fIsig\fP is invalid.
+.sp
+\fB\-EPERM\fP if no permission to send the \fIsig\fP\&.
+.sp
+\fB\-EAGAIN\fP if bpf program can try again.
+.UNINDENT
+.TP
+.B \fBs64 bpf_tcp_gen_syncookie(void *\fP\fIsk\fP\fB, void *\fP\fIiph\fP\fB, u32\fP \fIiph_len\fP\fB, struct tcphdr *\fP\fIth\fP\fB, u32\fP \fIth_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Try to issue a SYN cookie for the packet with corresponding
+IP/TCP headers, \fIiph\fP and \fIth\fP, on the listening socket in \fIsk\fP\&.
+.sp
+\fIiph\fP points to the start of the IPv4 or IPv6 header, while
+\fIiph_len\fP contains \fBsizeof\fP(\fBstruct iphdr\fP) or
+\fBsizeof\fP(\fBstruct ipv6hdr\fP).
+.sp
+\fIth\fP points to the start of the TCP header, while \fIth_len\fP
+contains the length of the TCP header with options (at least
+\fBsizeof\fP(\fBstruct tcphdr\fP)).
+.TP
+.B Return
+On success, lower 32 bits hold the generated SYN cookie in
+followed by 16 bits which hold the MSS value for that cookie,
+and the top 16 bits are unused.
+.sp
+On failure, the returned value is one of the following:
+.sp
+\fB\-EINVAL\fP SYN cookie cannot be issued due to error
+.sp
+\fB\-ENOENT\fP SYN cookie should not be issued (no SYN flood)
+.sp
+\fB\-EOPNOTSUPP\fP kernel configuration does not enable SYN cookies
+.sp
+\fB\-EPROTONOSUPPORT\fP IP packet version is not 4 or 6
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_output(void *\fP\fIctx\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB, void *\fP\fIdata\fP\fB, u64\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Write raw \fIdata\fP blob into a special BPF perf event held by
+\fImap\fP of type \fBBPF_MAP_TYPE_PERF_EVENT_ARRAY\fP\&. This perf
+event must have the following attributes: \fBPERF_SAMPLE_RAW\fP
+as \fBsample_type\fP, \fBPERF_TYPE_SOFTWARE\fP as \fBtype\fP, and
+\fBPERF_COUNT_SW_BPF_OUTPUT\fP as \fBconfig\fP\&.
+.sp
+The \fIflags\fP are used to indicate the index in \fImap\fP for which
+the value must be put, masked with \fBBPF_F_INDEX_MASK\fP\&.
+Alternatively, \fIflags\fP can be set to \fBBPF_F_CURRENT_CPU\fP
+to indicate that the index of the current CPU core should be
+used.
+.sp
+The value to write, of \fIsize\fP, is passed through eBPF stack and
+pointed by \fIdata\fP\&.
+.sp
+\fIctx\fP is a pointer to in\-kernel struct sk_buff.
+.sp
+This helper is similar to \fBbpf_perf_event_output\fP() but
+restricted to raw_tracepoint bpf programs.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_probe_read_user(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIunsafe_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Safely attempt to read \fIsize\fP bytes from user space address
+\fIunsafe_ptr\fP and store the data in \fIdst\fP\&.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_probe_read_kernel(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIunsafe_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Safely attempt to read \fIsize\fP bytes from kernel space address
+\fIunsafe_ptr\fP and store the data in \fIdst\fP\&.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_probe_read_user_str(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIunsafe_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Copy a NUL terminated string from an unsafe user address
+\fIunsafe_ptr\fP to \fIdst\fP\&. The \fIsize\fP should include the
+terminating NUL byte. In case the string length is smaller than
+\fIsize\fP, the target is not padded with further NUL bytes. If the
+string length is larger than \fIsize\fP, just \fIsize\fP\-1 bytes are
+copied and the last byte is set to NUL.
+.sp
+On success, returns the number of bytes that were written,
+including the terminal NUL. This makes this helper useful in
+tracing programs for reading strings, and more importantly to
+get its length at runtime. See the following snippet:
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+SEC(\(dqkprobe/sys_open\(dq)
+void bpf_sys_open(struct pt_regs *ctx)
+{
+        char buf[PATHLEN]; // PATHLEN is defined to 256
+        int res = bpf_probe_read_user_str(buf, sizeof(buf),
+                                          ctx\->di);
+
+        // Consume buf, for example push it to
+        // userspace via bpf_perf_event_output(); we
+        // can use res (the string length) as event
+        // size, after checking its boundaries.
+}
+.EE
+.UNINDENT
+.UNINDENT
+.sp
+In comparison, using \fBbpf_probe_read_user\fP() helper here
+instead to read the string would require to estimate the length
+at compile time, and would often result in copying more memory
+than necessary.
+.sp
+Another useful use case is when parsing individual process
+arguments or individual environment variables navigating
+\fIcurrent\fP\fB\->mm\->arg_start\fP and \fIcurrent\fP\fB\->mm\->env_start\fP: using this helper and the return value,
+one can quickly iterate at the right offset of the memory area.
+.TP
+.B Return
+On success, the strictly positive length of the output string,
+including the trailing NUL character. On error, a negative
+value.
+.UNINDENT
+.TP
+.B \fBlong bpf_probe_read_kernel_str(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIunsafe_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Copy a NUL terminated string from an unsafe kernel address \fIunsafe_ptr\fP
+to \fIdst\fP\&. Same semantics as with \fBbpf_probe_read_user_str\fP() apply.
+.TP
+.B Return
+On success, the strictly positive length of the string, including
+the trailing NUL character. On error, a negative value.
+.UNINDENT
+.TP
+.B \fBlong bpf_tcp_send_ack(void *\fP\fItp\fP\fB, u32\fP \fIrcv_nxt\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Send out a tcp\-ack. \fItp\fP is the in\-kernel struct \fBtcp_sock\fP\&.
+\fIrcv_nxt\fP is the ack_seq to be sent out.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_send_signal_thread(u32\fP \fIsig\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Send signal \fIsig\fP to the thread corresponding to the current task.
+.TP
+.B Return
+0 on success or successfully queued.
+.sp
+\fB\-EBUSY\fP if work queue under nmi is full.
+.sp
+\fB\-EINVAL\fP if \fIsig\fP is invalid.
+.sp
+\fB\-EPERM\fP if no permission to send the \fIsig\fP\&.
+.sp
+\fB\-EAGAIN\fP if bpf program can try again.
+.UNINDENT
+.TP
+.B \fBu64 bpf_jiffies64(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Obtain the 64bit jiffies
+.TP
+.B Return
+The 64 bit jiffies
+.UNINDENT
+.TP
+.B \fBlong bpf_read_branch_records(struct bpf_perf_event_data *\fP\fIctx\fP\fB, void *\fP\fIbuf\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For an eBPF program attached to a perf event, retrieve the
+branch records (\fBstruct perf_branch_entry\fP) associated to \fIctx\fP
+and store it in the buffer pointed by \fIbuf\fP up to size
+\fIsize\fP bytes.
+.TP
+.B Return
+On success, number of bytes written to \fIbuf\fP\&. On error, a
+negative value.
+.sp
+The \fIflags\fP can be set to \fBBPF_F_GET_BRANCH_RECORDS_SIZE\fP to
+instead return the number of bytes required to store all the
+branch entries. If this flag is set, \fIbuf\fP may be NULL.
+.sp
+\fB\-EINVAL\fP if arguments invalid or \fBsize\fP not a multiple
+of \fBsizeof\fP(\fBstruct perf_branch_entry\fP).
+.sp
+\fB\-ENOENT\fP if architecture does not support branch records.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_ns_current_pid_tgid(u64\fP \fIdev\fP\fB, u64\fP \fIino\fP\fB, struct bpf_pidns_info *\fP\fInsdata\fP\fB, u32\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Returns 0 on success, values for \fIpid\fP and \fItgid\fP as seen from the current
+\fInamespace\fP will be returned in \fInsdata\fP\&.
+.TP
+.B Return
+0 on success, or one of the following in case of failure:
+.sp
+\fB\-EINVAL\fP if dev and inum supplied don\(aqt match dev_t and inode number
+with nsfs of current task, or if dev conversion to dev_t lost high bits.
+.sp
+\fB\-ENOENT\fP if pidns does not exists for the current task.
+.UNINDENT
+.TP
+.B \fBlong bpf_xdp_output(void *\fP\fIctx\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB, void *\fP\fIdata\fP\fB, u64\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Write raw \fIdata\fP blob into a special BPF perf event held by
+\fImap\fP of type \fBBPF_MAP_TYPE_PERF_EVENT_ARRAY\fP\&. This perf
+event must have the following attributes: \fBPERF_SAMPLE_RAW\fP
+as \fBsample_type\fP, \fBPERF_TYPE_SOFTWARE\fP as \fBtype\fP, and
+\fBPERF_COUNT_SW_BPF_OUTPUT\fP as \fBconfig\fP\&.
+.sp
+The \fIflags\fP are used to indicate the index in \fImap\fP for which
+the value must be put, masked with \fBBPF_F_INDEX_MASK\fP\&.
+Alternatively, \fIflags\fP can be set to \fBBPF_F_CURRENT_CPU\fP
+to indicate that the index of the current CPU core should be
+used.
+.sp
+The value to write, of \fIsize\fP, is passed through eBPF stack and
+pointed by \fIdata\fP\&.
+.sp
+\fIctx\fP is a pointer to in\-kernel struct xdp_buff.
+.sp
+This helper is similar to \fBbpf_perf_eventoutput\fP() but
+restricted to raw_tracepoint bpf programs.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_netns_cookie(void *\fP\fIctx\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Retrieve the cookie (generated by the kernel) of the network
+namespace the input \fIctx\fP is associated with. The network
+namespace cookie remains stable for its lifetime and provides
+a global identifier that can be assumed unique. If \fIctx\fP is
+NULL, then the helper returns the cookie for the initial
+network namespace. The cookie itself is very similar to that
+of \fBbpf_get_socket_cookie\fP() helper, but for network
+namespaces instead of sockets.
+.TP
+.B Return
+A 8\-byte long opaque number.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_current_ancestor_cgroup_id(int\fP \fIancestor_level\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return id of cgroup v2 that is ancestor of the cgroup associated
+with the current task at the \fIancestor_level\fP\&. The root cgroup
+is at \fIancestor_level\fP zero and each step down the hierarchy
+increments the level. If \fIancestor_level\fP == level of cgroup
+associated with the current task, then return value will be the
+same as that of \fBbpf_get_current_cgroup_id\fP().
+.sp
+The helper is useful to implement policies based on cgroups
+that are upper in hierarchy than immediate cgroup associated
+with the current task.
+.sp
+The format of returned id and helper limitations are same as in
+\fBbpf_get_current_cgroup_id\fP().
+.TP
+.B Return
+The id is returned or 0 in case the id could not be retrieved.
+.UNINDENT
+.TP
+.B \fBlong bpf_sk_assign(struct sk_buff *\fP\fIskb\fP\fB, void *\fP\fIsk\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Helper is overloaded depending on BPF program type. This
+description applies to \fBBPF_PROG_TYPE_SCHED_CLS\fP and
+\fBBPF_PROG_TYPE_SCHED_ACT\fP programs.
+.sp
+Assign the \fIsk\fP to the \fIskb\fP\&. When combined with appropriate
+routing configuration to receive the packet towards the socket,
+will cause \fIskb\fP to be delivered to the specified socket.
+Subsequent redirection of \fIskb\fP via  \fBbpf_redirect\fP(),
+\fBbpf_clone_redirect\fP() or other methods outside of BPF may
+interfere with successful delivery to the socket.
+.sp
+This operation is only valid from TC ingress path.
+.sp
+The \fIflags\fP argument must be zero.
+.TP
+.B Return
+0 on success, or a negative error in case of failure:
+.sp
+\fB\-EINVAL\fP if specified \fIflags\fP are not supported.
+.sp
+\fB\-ENOENT\fP if the socket is unavailable for assignment.
+.sp
+\fB\-ENETUNREACH\fP if the socket is unreachable (wrong netns).
+.sp
+\fB\-EOPNOTSUPP\fP if the operation is not supported, for example
+a call from outside of TC ingress.
+.UNINDENT
+.TP
+.B \fBlong bpf_sk_assign(struct bpf_sk_lookup *\fP\fIctx\fP\fB, struct bpf_sock *\fP\fIsk\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Helper is overloaded depending on BPF program type. This
+description applies to \fBBPF_PROG_TYPE_SK_LOOKUP\fP programs.
+.sp
+Select the \fIsk\fP as a result of a socket lookup.
+.sp
+For the operation to succeed passed socket must be compatible
+with the packet description provided by the \fIctx\fP object.
+.sp
+L4 protocol (\fBIPPROTO_TCP\fP or \fBIPPROTO_UDP\fP) must
+be an exact match. While IP family (\fBAF_INET\fP or
+\fBAF_INET6\fP) must be compatible, that is IPv6 sockets
+that are not v6\-only can be selected for IPv4 packets.
+.sp
+Only TCP listeners and UDP unconnected sockets can be
+selected. \fIsk\fP can also be NULL to reset any previous
+selection.
+.sp
+\fIflags\fP argument can combination of following values:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_SK_LOOKUP_F_REPLACE\fP to override the previous
+socket selection, potentially done by a BPF program
+that ran before us.
+.IP \(bu 2
+\fBBPF_SK_LOOKUP_F_NO_REUSEPORT\fP to skip
+load\-balancing within reuseport group for the socket
+being selected.
+.UNINDENT
+.sp
+On success \fIctx\->sk\fP will point to the selected socket.
+.TP
+.B Return
+0 on success, or a negative errno in case of failure.
+.INDENT 7.0
+.IP \(bu 2
+\fB\-EAFNOSUPPORT\fP if socket family (\fIsk\->family\fP) is
+not compatible with packet family (\fIctx\->family\fP).
+.IP \(bu 2
+\fB\-EEXIST\fP if socket has been already selected,
+potentially by another program, and
+\fBBPF_SK_LOOKUP_F_REPLACE\fP flag was not specified.
+.IP \(bu 2
+\fB\-EINVAL\fP if unsupported flags were specified.
+.IP \(bu 2
+\fB\-EPROTOTYPE\fP if socket L4 protocol
+(\fIsk\->protocol\fP) doesn\(aqt match packet protocol
+(\fIctx\->protocol\fP).
+.IP \(bu 2
+\fB\-ESOCKTNOSUPPORT\fP if socket is not in allowed
+state (TCP listening or UDP unconnected).
+.UNINDENT
+.UNINDENT
+.TP
+.B \fBu64 bpf_ktime_get_boot_ns(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return the time elapsed since system boot, in nanoseconds.
+Does include the time the system was suspended.
+See: \fBclock_gettime\fP(\fBCLOCK_BOOTTIME\fP)
+.TP
+.B Return
+Current \fIktime\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_seq_printf(struct seq_file *\fP\fIm\fP\fB, const char *\fP\fIfmt\fP\fB, u32\fP \fIfmt_size\fP\fB, const void *\fP\fIdata\fP\fB, u32\fP \fIdata_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+\fBbpf_seq_printf\fP() uses seq_file \fBseq_printf\fP() to print
+out the format string.
+The \fIm\fP represents the seq_file. The \fIfmt\fP and \fIfmt_size\fP are for
+the format string itself. The \fIdata\fP and \fIdata_len\fP are format string
+arguments. The \fIdata\fP are a \fBu64\fP array and corresponding format string
+values are stored in the array. For strings and pointers where pointees
+are accessed, only the pointer values are stored in the \fIdata\fP array.
+The \fIdata_len\fP is the size of \fIdata\fP in bytes \- must be a multiple of 8.
+.sp
+Formats \fB%s\fP, \fB%p{i,I}{4,6}\fP requires to read kernel memory.
+Reading kernel memory may fail due to either invalid address or
+valid address but requiring a major memory fault. If reading kernel memory
+fails, the string for \fB%s\fP will be an empty string, and the ip
+address for \fB%p{i,I}{4,6}\fP will be 0. Not returning error to
+bpf program is consistent with what \fBbpf_trace_printk\fP() does for now.
+.TP
+.B Return
+0 on success, or a negative error in case of failure:
+.sp
+\fB\-EBUSY\fP if per\-CPU memory copy buffer is busy, can try again
+by returning 1 from bpf program.
+.sp
+\fB\-EINVAL\fP if arguments are invalid, or if \fIfmt\fP is invalid/unsupported.
+.sp
+\fB\-E2BIG\fP if \fIfmt\fP contains too many format specifiers.
+.sp
+\fB\-EOVERFLOW\fP if an overflow happened: The same object will be tried again.
+.UNINDENT
+.TP
+.B \fBlong bpf_seq_write(struct seq_file *\fP\fIm\fP\fB, const void *\fP\fIdata\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+\fBbpf_seq_write\fP() uses seq_file \fBseq_write\fP() to write the data.
+The \fIm\fP represents the seq_file. The \fIdata\fP and \fIlen\fP represent the
+data to write in bytes.
+.TP
+.B Return
+0 on success, or a negative error in case of failure:
+.sp
+\fB\-EOVERFLOW\fP if an overflow happened: The same object will be tried again.
+.UNINDENT
+.TP
+.B \fBu64 bpf_sk_cgroup_id(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return the cgroup v2 id of the socket \fIsk\fP\&.
+.sp
+\fIsk\fP must be a non\-\fBNULL\fP pointer to a socket, e.g. one
+returned from \fBbpf_sk_lookup_xxx\fP(),
+\fBbpf_sk_fullsock\fP(), etc. The format of returned id is
+same as in \fBbpf_skb_cgroup_id\fP().
+.sp
+This helper is available only if the kernel was compiled with
+the \fBCONFIG_SOCK_CGROUP_DATA\fP configuration option.
+.TP
+.B Return
+The id is returned or 0 in case the id could not be retrieved.
+.UNINDENT
+.TP
+.B \fBu64 bpf_sk_ancestor_cgroup_id(void *\fP\fIsk\fP\fB, int\fP \fIancestor_level\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return id of cgroup v2 that is ancestor of cgroup associated
+with the \fIsk\fP at the \fIancestor_level\fP\&.  The root cgroup is at
+\fIancestor_level\fP zero and each step down the hierarchy
+increments the level. If \fIancestor_level\fP == level of cgroup
+associated with \fIsk\fP, then return value will be same as that
+of \fBbpf_sk_cgroup_id\fP().
+.sp
+The helper is useful to implement policies based on cgroups
+that are upper in hierarchy than immediate cgroup associated
+with \fIsk\fP\&.
+.sp
+The format of returned id and helper limitations are same as in
+\fBbpf_sk_cgroup_id\fP().
+.TP
+.B Return
+The id is returned or 0 in case the id could not be retrieved.
+.UNINDENT
+.TP
+.B \fBlong bpf_ringbuf_output(void *\fP\fIringbuf\fP\fB, void *\fP\fIdata\fP\fB, u64\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Copy \fIsize\fP bytes from \fIdata\fP into a ring buffer \fIringbuf\fP\&.
+If \fBBPF_RB_NO_WAKEUP\fP is specified in \fIflags\fP, no notification
+of new data availability is sent.
+If \fBBPF_RB_FORCE_WAKEUP\fP is specified in \fIflags\fP, notification
+of new data availability is sent unconditionally.
+If \fB0\fP is specified in \fIflags\fP, an adaptive notification
+of new data availability is sent.
+.sp
+An adaptive notification is a notification sent whenever the user\-space
+process has caught up and consumed all available payloads. In case the user\-space
+process is still processing a previous payload, then no notification is needed
+as it will process the newly added payload automatically.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_ringbuf_reserve(void *\fP\fIringbuf\fP\fB, u64\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Reserve \fIsize\fP bytes of payload in a ring buffer \fIringbuf\fP\&.
+\fIflags\fP must be 0.
+.TP
+.B Return
+Valid pointer with \fIsize\fP bytes of memory available; NULL,
+otherwise.
+.UNINDENT
+.TP
+.B \fBvoid bpf_ringbuf_submit(void *\fP\fIdata\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Submit reserved ring buffer sample, pointed to by \fIdata\fP\&.
+If \fBBPF_RB_NO_WAKEUP\fP is specified in \fIflags\fP, no notification
+of new data availability is sent.
+If \fBBPF_RB_FORCE_WAKEUP\fP is specified in \fIflags\fP, notification
+of new data availability is sent unconditionally.
+If \fB0\fP is specified in \fIflags\fP, an adaptive notification
+of new data availability is sent.
+.sp
+See \(aqbpf_ringbuf_output()\(aq for the definition of adaptive notification.
+.TP
+.B Return
+Nothing. Always succeeds.
+.UNINDENT
+.TP
+.B \fBvoid bpf_ringbuf_discard(void *\fP\fIdata\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Discard reserved ring buffer sample, pointed to by \fIdata\fP\&.
+If \fBBPF_RB_NO_WAKEUP\fP is specified in \fIflags\fP, no notification
+of new data availability is sent.
+If \fBBPF_RB_FORCE_WAKEUP\fP is specified in \fIflags\fP, notification
+of new data availability is sent unconditionally.
+If \fB0\fP is specified in \fIflags\fP, an adaptive notification
+of new data availability is sent.
+.sp
+See \(aqbpf_ringbuf_output()\(aq for the definition of adaptive notification.
+.TP
+.B Return
+Nothing. Always succeeds.
+.UNINDENT
+.TP
+.B \fBu64 bpf_ringbuf_query(void *\fP\fIringbuf\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Query various characteristics of provided ring buffer. What
+exactly is queries is determined by \fIflags\fP:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_RB_AVAIL_DATA\fP: Amount of data not yet consumed.
+.IP \(bu 2
+\fBBPF_RB_RING_SIZE\fP: The size of ring buffer.
+.IP \(bu 2
+\fBBPF_RB_CONS_POS\fP: Consumer position (can wrap around).
+.IP \(bu 2
+\fBBPF_RB_PROD_POS\fP: Producer(s) position (can wrap around).
+.UNINDENT
+.sp
+Data returned is just a momentary snapshot of actual values
+and could be inaccurate, so this facility should be used to
+power heuristics and for reporting, not to make 100% correct
+calculation.
+.TP
+.B Return
+Requested value, or 0, if \fIflags\fP are not recognized.
+.UNINDENT
+.TP
+.B \fBlong bpf_csum_level(struct sk_buff *\fP\fIskb\fP\fB, u64\fP \fIlevel\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Change the skbs checksum level by one layer up or down, or
+reset it entirely to none in order to have the stack perform
+checksum validation. The level is applicable to the following
+protocols: TCP, UDP, GRE, SCTP, FCOE. For example, a decap of
+| ETH | IP | UDP | GUE | IP | TCP | into | ETH | IP | TCP |
+through \fBbpf_skb_adjust_room\fP() helper with passing in
+\fBBPF_F_ADJ_ROOM_NO_CSUM_RESET\fP flag would require one call
+to \fBbpf_csum_level\fP() with \fBBPF_CSUM_LEVEL_DEC\fP since
+the UDP header is removed. Similarly, an encap of the latter
+into the former could be accompanied by a helper call to
+\fBbpf_csum_level\fP() with \fBBPF_CSUM_LEVEL_INC\fP if the
+skb is still intended to be processed in higher layers of the
+stack instead of just egressing at tc.
+.sp
+There are three supported level settings at this time:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_CSUM_LEVEL_INC\fP: Increases skb\->csum_level for skbs
+with CHECKSUM_UNNECESSARY.
+.IP \(bu 2
+\fBBPF_CSUM_LEVEL_DEC\fP: Decreases skb\->csum_level for skbs
+with CHECKSUM_UNNECESSARY.
+.IP \(bu 2
+\fBBPF_CSUM_LEVEL_RESET\fP: Resets skb\->csum_level to 0 and
+sets CHECKSUM_NONE to force checksum validation by the stack.
+.IP \(bu 2
+\fBBPF_CSUM_LEVEL_QUERY\fP: No\-op, returns the current
+skb\->csum_level.
+.UNINDENT
+.TP
+.B Return
+0 on success, or a negative error in case of failure. In the
+case of \fBBPF_CSUM_LEVEL_QUERY\fP, the current skb\->csum_level
+is returned or the error code \-EACCES in case the skb is not
+subject to CHECKSUM_UNNECESSARY.
+.UNINDENT
+.TP
+.B \fBstruct tcp6_sock *bpf_skc_to_tcp6_sock(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Dynamically cast a \fIsk\fP pointer to a \fItcp6_sock\fP pointer.
+.TP
+.B Return
+\fIsk\fP if casting is valid, or \fBNULL\fP otherwise.
+.UNINDENT
+.TP
+.B \fBstruct tcp_sock *bpf_skc_to_tcp_sock(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Dynamically cast a \fIsk\fP pointer to a \fItcp_sock\fP pointer.
+.TP
+.B Return
+\fIsk\fP if casting is valid, or \fBNULL\fP otherwise.
+.UNINDENT
+.TP
+.B \fBstruct tcp_timewait_sock *bpf_skc_to_tcp_timewait_sock(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Dynamically cast a \fIsk\fP pointer to a \fItcp_timewait_sock\fP pointer.
+.TP
+.B Return
+\fIsk\fP if casting is valid, or \fBNULL\fP otherwise.
+.UNINDENT
+.TP
+.B \fBstruct tcp_request_sock *bpf_skc_to_tcp_request_sock(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Dynamically cast a \fIsk\fP pointer to a \fItcp_request_sock\fP pointer.
+.TP
+.B Return
+\fIsk\fP if casting is valid, or \fBNULL\fP otherwise.
+.UNINDENT
+.TP
+.B \fBstruct udp6_sock *bpf_skc_to_udp6_sock(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Dynamically cast a \fIsk\fP pointer to a \fIudp6_sock\fP pointer.
+.TP
+.B Return
+\fIsk\fP if casting is valid, or \fBNULL\fP otherwise.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_task_stack(struct task_struct *\fP\fItask\fP\fB, void *\fP\fIbuf\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return a user or a kernel stack in bpf program provided buffer.
+Note: the user stack will only be populated if the \fItask\fP is
+the current task; all other tasks will return \-EOPNOTSUPP.
+To achieve this, the helper needs \fItask\fP, which is a valid
+pointer to \fBstruct task_struct\fP\&. To store the stacktrace, the
+bpf program provides \fIbuf\fP with a nonnegative \fIsize\fP\&.
+.sp
+The last argument, \fIflags\fP, holds the number of stack frames to
+skip (from 0 to 255), masked with
+\fBBPF_F_SKIP_FIELD_MASK\fP\&. The next bits can be used to set
+the following flags:
+.INDENT 7.0
+.TP
+.B \fBBPF_F_USER_STACK\fP
+Collect a user space stack instead of a kernel stack.
+The \fItask\fP must be the current task.
+.TP
+.B \fBBPF_F_USER_BUILD_ID\fP
+Collect buildid+offset instead of ips for user stack,
+only valid if \fBBPF_F_USER_STACK\fP is also specified.
+.UNINDENT
+.sp
+\fBbpf_get_task_stack\fP() can collect up to
+\fBPERF_MAX_STACK_DEPTH\fP both kernel and user frames, subject
+to sufficient large buffer size. Note that
+this limit can be controlled with the \fBsysctl\fP program, and
+that it should be manually increased in order to profile long
+user stacks (such as stacks for Java programs). To do so, use:
+.INDENT 7.0
+.INDENT 3.5
+.sp
+.EX
+# sysctl kernel.perf_event_max_stack=<new value>
+.EE
+.UNINDENT
+.UNINDENT
+.TP
+.B Return
+The non\-negative copied \fIbuf\fP length equal to or less than
+\fIsize\fP on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_load_hdr_opt(struct bpf_sock_ops *\fP\fIskops\fP\fB, void *\fP\fIsearchby_res\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Load header option.  Support reading a particular TCP header
+option for bpf program (\fBBPF_PROG_TYPE_SOCK_OPS\fP).
+.sp
+If \fIflags\fP is 0, it will search the option from the
+\fIskops\fP\fB\->skb_data\fP\&.  The comment in \fBstruct bpf_sock_ops\fP
+has details on what skb_data contains under different
+\fIskops\fP\fB\->op\fP\&.
+.sp
+The first byte of the \fIsearchby_res\fP specifies the
+kind that it wants to search.
+.sp
+If the searching kind is an experimental kind
+(i.e. 253 or 254 according to RFC6994).  It also
+needs to specify the \(dqmagic\(dq which is either
+2 bytes or 4 bytes.  It then also needs to
+specify the size of the magic by using
+the 2nd byte which is \(dqkind\-length\(dq of a TCP
+header option and the \(dqkind\-length\(dq also
+includes the first 2 bytes \(dqkind\(dq and \(dqkind\-length\(dq
+itself as a normal TCP header option also does.
+.sp
+For example, to search experimental kind 254 with
+2 byte magic 0xeB9F, the searchby_res should be
+[ 254, 4, 0xeB, 0x9F, 0, 0, .... 0 ].
+.sp
+To search for the standard window scale option (3),
+the \fIsearchby_res\fP should be [ 3, 0, 0, .... 0 ].
+Note, kind\-length must be 0 for regular option.
+.sp
+Searching for No\-Op (0) and End\-of\-Option\-List (1) are
+not supported.
+.sp
+\fIlen\fP must be at least 2 bytes which is the minimal size
+of a header option.
+.sp
+Supported flags:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_LOAD_HDR_OPT_TCP_SYN\fP to search from the
+saved_syn packet or the just\-received syn packet.
+.UNINDENT
+.TP
+.B Return
+> 0 when found, the header option is copied to \fIsearchby_res\fP\&.
+The return value is the total length copied. On failure, a
+negative error code is returned:
+.sp
+\fB\-EINVAL\fP if a parameter is invalid.
+.sp
+\fB\-ENOMSG\fP if the option is not found.
+.sp
+\fB\-ENOENT\fP if no syn packet is available when
+\fBBPF_LOAD_HDR_OPT_TCP_SYN\fP is used.
+.sp
+\fB\-ENOSPC\fP if there is not enough space.  Only \fIlen\fP number of
+bytes are copied.
+.sp
+\fB\-EFAULT\fP on failure to parse the header options in the
+packet.
+.sp
+\fB\-EPERM\fP if the helper cannot be used under the current
+\fIskops\fP\fB\->op\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_store_hdr_opt(struct bpf_sock_ops *\fP\fIskops\fP\fB, const void *\fP\fIfrom\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Store header option.  The data will be copied
+from buffer \fIfrom\fP with length \fIlen\fP to the TCP header.
+.sp
+The buffer \fIfrom\fP should have the whole option that
+includes the kind, kind\-length, and the actual
+option data.  The \fIlen\fP must be at least kind\-length
+long.  The kind\-length does not have to be 4 byte
+aligned.  The kernel will take care of the padding
+and setting the 4 bytes aligned value to th\->doff.
+.sp
+This helper will check for duplicated option
+by searching the same option in the outgoing skb.
+.sp
+This helper can only be called during
+\fBBPF_SOCK_OPS_WRITE_HDR_OPT_CB\fP\&.
+.TP
+.B Return
+0 on success, or negative error in case of failure:
+.sp
+\fB\-EINVAL\fP If param is invalid.
+.sp
+\fB\-ENOSPC\fP if there is not enough space in the header.
+Nothing has been written
+.sp
+\fB\-EEXIST\fP if the option already exists.
+.sp
+\fB\-EFAULT\fP on failure to parse the existing header options.
+.sp
+\fB\-EPERM\fP if the helper cannot be used under the current
+\fIskops\fP\fB\->op\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_reserve_hdr_opt(struct bpf_sock_ops *\fP\fIskops\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Reserve \fIlen\fP bytes for the bpf header option.  The
+space will be used by \fBbpf_store_hdr_opt\fP() later in
+\fBBPF_SOCK_OPS_WRITE_HDR_OPT_CB\fP\&.
+.sp
+If \fBbpf_reserve_hdr_opt\fP() is called multiple times,
+the total number of bytes will be reserved.
+.sp
+This helper can only be called during
+\fBBPF_SOCK_OPS_HDR_OPT_LEN_CB\fP\&.
+.TP
+.B Return
+0 on success, or negative error in case of failure:
+.sp
+\fB\-EINVAL\fP if a parameter is invalid.
+.sp
+\fB\-ENOSPC\fP if there is not enough space in the header.
+.sp
+\fB\-EPERM\fP if the helper cannot be used under the current
+\fIskops\fP\fB\->op\fP\&.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_inode_storage_get(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIinode\fP\fB, void *\fP\fIvalue\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get a bpf_local_storage from an \fIinode\fP\&.
+.sp
+Logically, it could be thought of as getting the value from
+a \fImap\fP with \fIinode\fP as the \fBkey\fP\&.  From this
+perspective,  the usage is not much different from
+\fBbpf_map_lookup_elem\fP(\fImap\fP, \fB&\fP\fIinode\fP) except this
+helper enforces the key must be an inode and the map must also
+be a \fBBPF_MAP_TYPE_INODE_STORAGE\fP\&.
+.sp
+Underneath, the value is stored locally at \fIinode\fP instead of
+the \fImap\fP\&.  The \fImap\fP is used as the bpf\-local\-storage
+\(dqtype\(dq. The bpf\-local\-storage \(dqtype\(dq (i.e. the \fImap\fP) is
+searched against all bpf_local_storage residing at \fIinode\fP\&.
+.sp
+An optional \fIflags\fP (\fBBPF_LOCAL_STORAGE_GET_F_CREATE\fP) can be
+used such that a new bpf_local_storage will be
+created if one does not exist.  \fIvalue\fP can be used
+together with \fBBPF_LOCAL_STORAGE_GET_F_CREATE\fP to specify
+the initial value of a bpf_local_storage.  If \fIvalue\fP is
+\fBNULL\fP, the new bpf_local_storage will be zero initialized.
+.TP
+.B Return
+A bpf_local_storage pointer is returned on success.
+.sp
+\fBNULL\fP if not found or there was an error in adding
+a new bpf_local_storage.
+.UNINDENT
+.TP
+.B \fBint bpf_inode_storage_delete(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIinode\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Delete a bpf_local_storage from an \fIinode\fP\&.
+.TP
+.B Return
+0 on success.
+.sp
+\fB\-ENOENT\fP if the bpf_local_storage cannot be found.
+.UNINDENT
+.TP
+.B \fBlong bpf_d_path(struct path *\fP\fIpath\fP\fB, char *\fP\fIbuf\fP\fB, u32\fP \fIsz\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return full path for given \fBstruct path\fP object, which
+needs to be the kernel BTF \fIpath\fP object. The path is
+returned in the provided buffer \fIbuf\fP of size \fIsz\fP and
+is zero terminated.
+.TP
+.B Return
+On success, the strictly positive length of the string,
+including the trailing NUL character. On error, a negative
+value.
+.UNINDENT
+.TP
+.B \fBlong bpf_copy_from_user(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIuser_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Read \fIsize\fP bytes from user space address \fIuser_ptr\fP and store
+the data in \fIdst\fP\&. This is a wrapper of \fBcopy_from_user\fP().
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_snprintf_btf(char *\fP\fIstr\fP\fB, u32\fP \fIstr_size\fP\fB, struct btf_ptr *\fP\fIptr\fP\fB, u32\fP \fIbtf_ptr_size\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Use BTF to store a string representation of \fIptr\fP\->ptr in \fIstr\fP,
+using \fIptr\fP\->type_id.  This value should specify the type
+that \fIptr\fP\->ptr points to. LLVM __builtin_btf_type_id(type, 1)
+can be used to look up vmlinux BTF type ids. Traversing the
+data structure using BTF, the type information and values are
+stored in the first \fIstr_size\fP \- 1 bytes of \fIstr\fP\&.  Safe copy of
+the pointer data is carried out to avoid kernel crashes during
+operation.  Smaller types can use string space on the stack;
+larger programs can use map data to store the string
+representation.
+.sp
+The string can be subsequently shared with userspace via
+bpf_perf_event_output() or ring buffer interfaces.
+bpf_trace_printk() is to be avoided as it places too small
+a limit on string size to be useful.
+.sp
+\fIflags\fP is a combination of
+.INDENT 7.0
+.TP
+.B \fBBTF_F_COMPACT\fP
+no formatting around type information
+.TP
+.B \fBBTF_F_NONAME\fP
+no struct/union member names/types
+.TP
+.B \fBBTF_F_PTR_RAW\fP
+show raw (unobfuscated) pointer values;
+equivalent to printk specifier %px.
+.TP
+.B \fBBTF_F_ZERO\fP
+show zero\-valued struct/union members; they
+are not displayed by default
+.UNINDENT
+.TP
+.B Return
+The number of bytes that were written (or would have been
+written if output had to be truncated due to string size),
+or a negative error in cases of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_seq_printf_btf(struct seq_file *\fP\fIm\fP\fB, struct btf_ptr *\fP\fIptr\fP\fB, u32\fP \fIptr_size\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Use BTF to write to seq_write a string representation of
+\fIptr\fP\->ptr, using \fIptr\fP\->type_id as per bpf_snprintf_btf().
+\fIflags\fP are identical to those used for bpf_snprintf_btf.
+.TP
+.B Return
+0 on success or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBu64 bpf_skb_cgroup_classid(struct sk_buff *\fP\fIskb\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+See \fBbpf_get_cgroup_classid\fP() for the main description.
+This helper differs from \fBbpf_get_cgroup_classid\fP() in that
+the cgroup v1 net_cls class is retrieved only from the \fIskb\fP\(aqs
+associated socket instead of the current process.
+.TP
+.B Return
+The id is returned or 0 in case the id could not be retrieved.
+.UNINDENT
+.TP
+.B \fBlong bpf_redirect_neigh(u32\fP \fIifindex\fP\fB, struct bpf_redir_neigh *\fP\fIparams\fP\fB, int\fP \fIplen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Redirect the packet to another net device of index \fIifindex\fP
+and fill in L2 addresses from neighboring subsystem. This helper
+is somewhat similar to \fBbpf_redirect\fP(), except that it
+populates L2 addresses as well, meaning, internally, the helper
+relies on the neighbor lookup for the L2 address of the nexthop.
+.sp
+The helper will perform a FIB lookup based on the skb\(aqs
+networking header to get the address of the next hop, unless
+this is supplied by the caller in the \fIparams\fP argument. The
+\fIplen\fP argument indicates the len of \fIparams\fP and should be set
+to 0 if \fIparams\fP is NULL.
+.sp
+The \fIflags\fP argument is reserved and must be 0. The helper is
+currently only supported for tc BPF program types, and enabled
+for IPv4 and IPv6 protocols.
+.TP
+.B Return
+The helper returns \fBTC_ACT_REDIRECT\fP on success or
+\fBTC_ACT_SHOT\fP on error.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_per_cpu_ptr(const void *\fP\fIpercpu_ptr\fP\fB, u32\fP \fIcpu\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Take a pointer to a percpu ksym, \fIpercpu_ptr\fP, and return a
+pointer to the percpu kernel variable on \fIcpu\fP\&. A ksym is an
+extern variable decorated with \(aq__ksym\(aq. For ksym, there is a
+global var (either static or global) defined of the same name
+in the kernel. The ksym is percpu if the global var is percpu.
+The returned pointer points to the global percpu var on \fIcpu\fP\&.
+.sp
+bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the
+kernel, except that bpf_per_cpu_ptr() may return NULL. This
+happens if \fIcpu\fP is larger than nr_cpu_ids. The caller of
+bpf_per_cpu_ptr() must check the returned value.
+.TP
+.B Return
+A pointer pointing to the kernel percpu variable on \fIcpu\fP, or
+NULL, if \fIcpu\fP is invalid.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_this_cpu_ptr(const void *\fP\fIpercpu_ptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Take a pointer to a percpu ksym, \fIpercpu_ptr\fP, and return a
+pointer to the percpu kernel variable on this cpu. See the
+description of \(aqksym\(aq in \fBbpf_per_cpu_ptr\fP().
+.sp
+bpf_this_cpu_ptr() has the same semantic as this_cpu_ptr() in
+the kernel. Different from \fBbpf_per_cpu_ptr\fP(), it would
+never return NULL.
+.TP
+.B Return
+A pointer pointing to the kernel percpu variable on this cpu.
+.UNINDENT
+.TP
+.B \fBlong bpf_redirect_peer(u32\fP \fIifindex\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Redirect the packet to another net device of index \fIifindex\fP\&.
+This helper is somewhat similar to \fBbpf_redirect\fP(), except
+that the redirection happens to the \fIifindex\fP\(aq peer device and
+the netns switch takes place from ingress to ingress without
+going through the CPU\(aqs backlog queue.
+.sp
+The \fIflags\fP argument is reserved and must be 0. The helper is
+currently only supported for tc BPF program types at the ingress
+hook and for veth device types. The peer device must reside in a
+different network namespace.
+.TP
+.B Return
+The helper returns \fBTC_ACT_REDIRECT\fP on success or
+\fBTC_ACT_SHOT\fP on error.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_task_storage_get(struct bpf_map *\fP\fImap\fP\fB, struct task_struct *\fP\fItask\fP\fB, void *\fP\fIvalue\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get a bpf_local_storage from the \fItask\fP\&.
+.sp
+Logically, it could be thought of as getting the value from
+a \fImap\fP with \fItask\fP as the \fBkey\fP\&.  From this
+perspective,  the usage is not much different from
+\fBbpf_map_lookup_elem\fP(\fImap\fP, \fB&\fP\fItask\fP) except this
+helper enforces the key must be a task_struct and the map must also
+be a \fBBPF_MAP_TYPE_TASK_STORAGE\fP\&.
+.sp
+Underneath, the value is stored locally at \fItask\fP instead of
+the \fImap\fP\&.  The \fImap\fP is used as the bpf\-local\-storage
+\(dqtype\(dq. The bpf\-local\-storage \(dqtype\(dq (i.e. the \fImap\fP) is
+searched against all bpf_local_storage residing at \fItask\fP\&.
+.sp
+An optional \fIflags\fP (\fBBPF_LOCAL_STORAGE_GET_F_CREATE\fP) can be
+used such that a new bpf_local_storage will be
+created if one does not exist.  \fIvalue\fP can be used
+together with \fBBPF_LOCAL_STORAGE_GET_F_CREATE\fP to specify
+the initial value of a bpf_local_storage.  If \fIvalue\fP is
+\fBNULL\fP, the new bpf_local_storage will be zero initialized.
+.TP
+.B Return
+A bpf_local_storage pointer is returned on success.
+.sp
+\fBNULL\fP if not found or there was an error in adding
+a new bpf_local_storage.
+.UNINDENT
+.TP
+.B \fBlong bpf_task_storage_delete(struct bpf_map *\fP\fImap\fP\fB, struct task_struct *\fP\fItask\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Delete a bpf_local_storage from a \fItask\fP\&.
+.TP
+.B Return
+0 on success.
+.sp
+\fB\-ENOENT\fP if the bpf_local_storage cannot be found.
+.UNINDENT
+.TP
+.B \fBstruct task_struct *bpf_get_current_task_btf(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return a BTF pointer to the \(dqcurrent\(dq task.
+This pointer can also be used in helpers that accept an
+\fIARG_PTR_TO_BTF_ID\fP of type \fItask_struct\fP\&.
+.TP
+.B Return
+Pointer to the current task.
+.UNINDENT
+.TP
+.B \fBlong bpf_bprm_opts_set(struct linux_binprm *\fP\fIbprm\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Set or clear certain options on \fIbprm\fP:
+.sp
+\fBBPF_F_BPRM_SECUREEXEC\fP Set the secureexec bit
+which sets the \fBAT_SECURE\fP auxv for glibc. The bit
+is cleared if the flag is not specified.
+.TP
+.B Return
+\fB\-EINVAL\fP if invalid \fIflags\fP are passed, zero otherwise.
+.UNINDENT
+.TP
+.B \fBu64 bpf_ktime_get_coarse_ns(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Return a coarse\-grained version of the time elapsed since
+system boot, in nanoseconds. Does not include time the system
+was suspended.
+.sp
+See: \fBclock_gettime\fP(\fBCLOCK_MONOTONIC_COARSE\fP)
+.TP
+.B Return
+Current \fIktime\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_ima_inode_hash(struct inode *\fP\fIinode\fP\fB, void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Returns the stored IMA hash of the \fIinode\fP (if it\(aqs available).
+If the hash is larger than \fIsize\fP, then only \fIsize\fP
+bytes will be copied to \fIdst\fP
+.TP
+.B Return
+The \fBhash_algo\fP is returned on success,
+\fB\-EOPNOTSUP\fP if IMA is disabled or \fB\-EINVAL\fP if
+invalid arguments are passed.
+.UNINDENT
+.TP
+.B \fBstruct socket *bpf_sock_from_file(struct file *\fP\fIfile\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+If the given file represents a socket, returns the associated
+socket.
+.TP
+.B Return
+A pointer to a struct socket on success or NULL if the file is
+not a socket.
+.UNINDENT
+.TP
+.B \fBlong bpf_check_mtu(void *\fP\fIctx\fP\fB, u32\fP \fIifindex\fP\fB, u32 *\fP\fImtu_len\fP\fB, s32\fP \fIlen_diff\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Check packet size against exceeding MTU of net device (based
+on \fIifindex\fP).  This helper will likely be used in combination
+with helpers that adjust/change the packet size.
+.sp
+The argument \fIlen_diff\fP can be used for querying with a planned
+size change. This allows to check MTU prior to changing packet
+ctx. Providing a \fIlen_diff\fP adjustment that is larger than the
+actual packet size (resulting in negative packet size) will in
+principle not exceed the MTU, which is why it is not considered
+a failure.  Other BPF helpers are needed for performing the
+planned size change; therefore the responsibility for catching
+a negative packet size belongs in those helpers.
+.sp
+Specifying \fIifindex\fP zero means the MTU check is performed
+against the current net device.  This is practical if this isn\(aqt
+used prior to redirect.
+.sp
+On input \fImtu_len\fP must be a valid pointer, else verifier will
+reject BPF program.  If the value \fImtu_len\fP is initialized to
+zero then the ctx packet size is use.  When value \fImtu_len\fP is
+provided as input this specify the L3 length that the MTU check
+is done against. Remember XDP and TC length operate at L2, but
+this value is L3 as this correlate to MTU and IP\-header tot_len
+values which are L3 (similar behavior as bpf_fib_lookup).
+.sp
+The Linux kernel route table can configure MTUs on a more
+specific per route level, which is not provided by this helper.
+For route level MTU checks use the \fBbpf_fib_lookup\fP()
+helper.
+.sp
+\fIctx\fP is either \fBstruct xdp_md\fP for XDP programs or
+\fBstruct sk_buff\fP for tc cls_act programs.
+.sp
+The \fIflags\fP argument can be a combination of one or more of the
+following values:
+.INDENT 7.0
+.TP
+.B \fBBPF_MTU_CHK_SEGS\fP
+This flag will only works for \fIctx\fP \fBstruct sk_buff\fP\&.
+If packet context contains extra packet segment buffers
+(often knows as GSO skb), then MTU check is harder to
+check at this point, because in transmit path it is
+possible for the skb packet to get re\-segmented
+(depending on net device features).  This could still be
+a MTU violation, so this flag enables performing MTU
+check against segments, with a different violation
+return code to tell it apart. Check cannot use len_diff.
+.UNINDENT
+.sp
+On return \fImtu_len\fP pointer contains the MTU value of the net
+device.  Remember the net device configured MTU is the L3 size,
+which is returned here and XDP and TC length operate at L2.
+Helper take this into account for you, but remember when using
+MTU value in your BPF\-code.
+.TP
+.B Return
+.INDENT 7.0
+.IP \(bu 2
+0 on success, and populate MTU value in \fImtu_len\fP pointer.
+.IP \(bu 2
+< 0 if any input argument is invalid (\fImtu_len\fP not updated)
+.UNINDENT
+.sp
+MTU violations return positive values, but also populate MTU
+value in \fImtu_len\fP pointer, as this can be needed for
+implementing PMTU handing:
+.INDENT 7.0
+.IP \(bu 2
+\fBBPF_MTU_CHK_RET_FRAG_NEEDED\fP
+.IP \(bu 2
+\fBBPF_MTU_CHK_RET_SEGS_TOOBIG\fP
+.UNINDENT
+.UNINDENT
+.TP
+.B \fBlong bpf_for_each_map_elem(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIcallback_fn\fP\fB, void *\fP\fIcallback_ctx\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For each element in \fBmap\fP, call \fBcallback_fn\fP function with
+\fBmap\fP, \fBcallback_ctx\fP and other map\-specific parameters.
+The \fBcallback_fn\fP should be a static function and
+the \fBcallback_ctx\fP should be a pointer to the stack.
+The \fBflags\fP is used to control certain aspects of the helper.
+Currently, the \fBflags\fP must be 0.
+.sp
+The following are a list of supported map types and their
+respective expected callback signatures:
+.sp
+BPF_MAP_TYPE_HASH, BPF_MAP_TYPE_PERCPU_HASH,
+BPF_MAP_TYPE_LRU_HASH, BPF_MAP_TYPE_LRU_PERCPU_HASH,
+BPF_MAP_TYPE_ARRAY, BPF_MAP_TYPE_PERCPU_ARRAY
+.sp
+long (*callback_fn)(struct bpf_map *map, const void *key, void *value, void *ctx);
+.sp
+For per_cpu maps, the map_value is the value on the cpu where the
+bpf_prog is running.
+.sp
+If \fBcallback_fn\fP return 0, the helper will continue to the next
+element. If return value is 1, the helper will skip the rest of
+elements and return. Other return values are not used now.
+.TP
+.B Return
+The number of traversed map elements for success, \fB\-EINVAL\fP for
+invalid \fBflags\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_snprintf(char *\fP\fIstr\fP\fB, u32\fP \fIstr_size\fP\fB, const char *\fP\fIfmt\fP\fB, u64 *\fP\fIdata\fP\fB, u32\fP \fIdata_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Outputs a string into the \fBstr\fP buffer of size \fBstr_size\fP
+based on a format string stored in a read\-only map pointed by
+\fBfmt\fP\&.
+.sp
+Each format specifier in \fBfmt\fP corresponds to one u64 element
+in the \fBdata\fP array. For strings and pointers where pointees
+are accessed, only the pointer values are stored in the \fIdata\fP
+array. The \fIdata_len\fP is the size of \fIdata\fP in bytes \- must be
+a multiple of 8.
+.sp
+Formats \fB%s\fP and \fB%p{i,I}{4,6}\fP require to read kernel
+memory. Reading kernel memory may fail due to either invalid
+address or valid address but requiring a major memory fault. If
+reading kernel memory fails, the string for \fB%s\fP will be an
+empty string, and the ip address for \fB%p{i,I}{4,6}\fP will be 0.
+Not returning error to bpf program is consistent with what
+\fBbpf_trace_printk\fP() does for now.
+.TP
+.B Return
+The strictly positive length of the formatted string, including
+the trailing zero character. If the return value is greater than
+\fBstr_size\fP, \fBstr\fP contains a truncated string, guaranteed to
+be zero\-terminated except when \fBstr_size\fP is 0.
+.sp
+Or \fB\-EBUSY\fP if the per\-CPU memory copy buffer is busy.
+.UNINDENT
+.TP
+.B \fBlong bpf_sys_bpf(u32\fP \fIcmd\fP\fB, void *\fP\fIattr\fP\fB, u32\fP \fIattr_size\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Execute bpf syscall with given arguments.
+.TP
+.B Return
+A syscall result.
+.UNINDENT
+.TP
+.B \fBlong bpf_btf_find_by_name_kind(char *\fP\fIname\fP\fB, int\fP \fIname_sz\fP\fB, u32\fP \fIkind\fP\fB, int\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Find BTF type with given name and kind in vmlinux BTF or in module\(aqs BTFs.
+.TP
+.B Return
+Returns btf_id and btf_obj_fd in lower and upper 32 bits.
+.UNINDENT
+.TP
+.B \fBlong bpf_sys_close(u32\fP \fIfd\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Execute close syscall for given FD.
+.TP
+.B Return
+A syscall result.
+.UNINDENT
+.TP
+.B \fBlong bpf_timer_init(struct bpf_timer *\fP\fItimer\fP\fB, struct bpf_map *\fP\fImap\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Initialize the timer.
+First 4 bits of \fIflags\fP specify clockid.
+Only CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME are allowed.
+All other bits of \fIflags\fP are reserved.
+The verifier will reject the program if \fItimer\fP is not from
+the same \fImap\fP\&.
+.TP
+.B Return
+0 on success.
+\fB\-EBUSY\fP if \fItimer\fP is already initialized.
+\fB\-EINVAL\fP if invalid \fIflags\fP are passed.
+\fB\-EPERM\fP if \fItimer\fP is in a map that doesn\(aqt have any user references.
+The user space should either hold a file descriptor to a map with timers
+or pin such map in bpffs. When map is unpinned or file descriptor is
+closed all timers in the map will be cancelled and freed.
+.UNINDENT
+.TP
+.B \fBlong bpf_timer_set_callback(struct bpf_timer *\fP\fItimer\fP\fB, void *\fP\fIcallback_fn\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Configure the timer to call \fIcallback_fn\fP static function.
+.TP
+.B Return
+0 on success.
+\fB\-EINVAL\fP if \fItimer\fP was not initialized with bpf_timer_init() earlier.
+\fB\-EPERM\fP if \fItimer\fP is in a map that doesn\(aqt have any user references.
+The user space should either hold a file descriptor to a map with timers
+or pin such map in bpffs. When map is unpinned or file descriptor is
+closed all timers in the map will be cancelled and freed.
+.UNINDENT
+.TP
+.B \fBlong bpf_timer_start(struct bpf_timer *\fP\fItimer\fP\fB, u64\fP \fInsecs\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Set timer expiration N nanoseconds from the current time. The
+configured callback will be invoked in soft irq context on some cpu
+and will not repeat unless another bpf_timer_start() is made.
+In such case the next invocation can migrate to a different cpu.
+Since struct bpf_timer is a field inside map element the map
+owns the timer. The bpf_timer_set_callback() will increment refcnt
+of BPF program to make sure that callback_fn code stays valid.
+When user space reference to a map reaches zero all timers
+in a map are cancelled and corresponding program\(aqs refcnts are
+decremented. This is done to make sure that Ctrl\-C of a user
+process doesn\(aqt leave any timers running. If map is pinned in
+bpffs the callback_fn can re\-arm itself indefinitely.
+bpf_map_update/delete_elem() helpers and user space sys_bpf commands
+cancel and free the timer in the given map element.
+The map can contain timers that invoke callback_fn\-s from different
+programs. The same callback_fn can serve different timers from
+different maps if key/value layout matches across maps.
+Every bpf_timer_set_callback() can have different callback_fn.
+.sp
+\fIflags\fP can be one of:
+.INDENT 7.0
+.TP
+.B \fBBPF_F_TIMER_ABS\fP
+Start the timer in absolute expire value instead of the
+default relative one.
+.TP
+.B \fBBPF_F_TIMER_CPU_PIN\fP
+Timer will be pinned to the CPU of the caller.
+.UNINDENT
+.TP
+.B Return
+0 on success.
+\fB\-EINVAL\fP if \fItimer\fP was not initialized with bpf_timer_init() earlier
+or invalid \fIflags\fP are passed.
+.UNINDENT
+.TP
+.B \fBlong bpf_timer_cancel(struct bpf_timer *\fP\fItimer\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Cancel the timer and wait for callback_fn to finish if it was running.
+.TP
+.B Return
+0 if the timer was not active.
+1 if the timer was active.
+\fB\-EINVAL\fP if \fItimer\fP was not initialized with bpf_timer_init() earlier.
+\fB\-EDEADLK\fP if callback_fn tried to call bpf_timer_cancel() on its
+own timer which would have led to a deadlock otherwise.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_func_ip(void *\fP\fIctx\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get address of the traced function (for tracing and kprobe programs).
+.sp
+When called for kprobe program attached as uprobe it returns
+probe address for both entry and return uprobe.
+.TP
+.B Return
+Address of the traced function for kprobe.
+0 for kprobes placed within the function (not at the entry).
+Address of the probe for uprobe and return uprobe.
+.UNINDENT
+.TP
+.B \fBu64 bpf_get_attach_cookie(void *\fP\fIctx\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get bpf_cookie value provided (optionally) during the program
+attachment. It might be different for each individual
+attachment, even if BPF program itself is the same.
+Expects BPF program context \fIctx\fP as a first argument.
+.INDENT 7.0
+.TP
+.B Supported for the following program types:
+.INDENT 7.0
+.IP \(bu 2
+kprobe/uprobe;
+.IP \(bu 2
+tracepoint;
+.IP \(bu 2
+perf_event.
+.UNINDENT
+.UNINDENT
+.TP
+.B Return
+Value specified by user at BPF link creation/attachment time
+or 0, if it was not specified.
+.UNINDENT
+.TP
+.B \fBlong bpf_task_pt_regs(struct task_struct *\fP\fItask\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the struct pt_regs associated with \fBtask\fP\&.
+.TP
+.B Return
+A pointer to struct pt_regs.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_branch_snapshot(void *\fP\fIentries\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get branch trace from hardware engines like Intel LBR. The
+hardware engine is stopped shortly after the helper is
+called. Therefore, the user need to filter branch entries
+based on the actual use case. To capture branch trace
+before the trigger point of the BPF program, the helper
+should be called at the beginning of the BPF program.
+.sp
+The data is stored as struct perf_branch_entry into output
+buffer \fIentries\fP\&. \fIsize\fP is the size of \fIentries\fP in bytes.
+\fIflags\fP is reserved for now and must be zero.
+.TP
+.B Return
+On success, number of bytes written to \fIbuf\fP\&. On error, a
+negative value.
+.sp
+\fB\-EINVAL\fP if \fIflags\fP is not zero.
+.sp
+\fB\-ENOENT\fP if architecture does not support branch records.
+.UNINDENT
+.TP
+.B \fBlong bpf_trace_vprintk(const char *\fP\fIfmt\fP\fB, u32\fP \fIfmt_size\fP\fB, const void *\fP\fIdata\fP\fB, u32\fP \fIdata_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Behaves like \fBbpf_trace_printk\fP() helper, but takes an array of u64
+to format and can handle more format args as a result.
+.sp
+Arguments are to be used as in \fBbpf_seq_printf\fP() helper.
+.TP
+.B Return
+The number of bytes written to the buffer, or a negative error
+in case of failure.
+.UNINDENT
+.TP
+.B \fBstruct unix_sock *bpf_skc_to_unix_sock(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Dynamically cast a \fIsk\fP pointer to a \fIunix_sock\fP pointer.
+.TP
+.B Return
+\fIsk\fP if casting is valid, or \fBNULL\fP otherwise.
+.UNINDENT
+.TP
+.B \fBlong bpf_kallsyms_lookup_name(const char *\fP\fIname\fP\fB, int\fP \fIname_sz\fP\fB, int\fP \fIflags\fP\fB, u64 *\fP\fIres\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the address of a kernel symbol, returned in \fIres\fP\&. \fIres\fP is
+set to 0 if the symbol is not found.
+.TP
+.B Return
+On success, zero. On error, a negative value.
+.sp
+\fB\-EINVAL\fP if \fIflags\fP is not zero.
+.sp
+\fB\-EINVAL\fP if string \fIname\fP is not the same size as \fIname_sz\fP\&.
+.sp
+\fB\-ENOENT\fP if symbol is not found.
+.sp
+\fB\-EPERM\fP if caller does not have permission to obtain kernel address.
+.UNINDENT
+.TP
+.B \fBlong bpf_find_vma(struct task_struct *\fP\fItask\fP\fB, u64\fP \fIaddr\fP\fB, void *\fP\fIcallback_fn\fP\fB, void *\fP\fIcallback_ctx\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Find vma of \fItask\fP that contains \fIaddr\fP, call \fIcallback_fn\fP
+function with \fItask\fP, \fIvma\fP, and \fIcallback_ctx\fP\&.
+The \fIcallback_fn\fP should be a static function and
+the \fIcallback_ctx\fP should be a pointer to the stack.
+The \fIflags\fP is used to control certain aspects of the helper.
+Currently, the \fIflags\fP must be 0.
+.sp
+The expected callback signature is
+.sp
+long (*callback_fn)(struct task_struct *task, struct vm_area_struct *vma, void *callback_ctx);
+.TP
+.B Return
+0 on success.
+\fB\-ENOENT\fP if \fItask\->mm\fP is NULL, or no vma contains \fIaddr\fP\&.
+\fB\-EBUSY\fP if failed to try lock mmap_lock.
+\fB\-EINVAL\fP for invalid \fBflags\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_loop(u32\fP \fInr_loops\fP\fB, void *\fP\fIcallback_fn\fP\fB, void *\fP\fIcallback_ctx\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+For \fBnr_loops\fP, call \fBcallback_fn\fP function
+with \fBcallback_ctx\fP as the context parameter.
+The \fBcallback_fn\fP should be a static function and
+the \fBcallback_ctx\fP should be a pointer to the stack.
+The \fBflags\fP is used to control certain aspects of the helper.
+Currently, the \fBflags\fP must be 0. Currently, nr_loops is
+limited to 1 << 23 (~8 million) loops.
+.sp
+long (*callback_fn)(u32 index, void *ctx);
+.sp
+where \fBindex\fP is the current index in the loop. The index
+is zero\-indexed.
+.sp
+If \fBcallback_fn\fP returns 0, the helper will continue to the next
+loop. If return value is 1, the helper will skip the rest of
+the loops and return. Other return values are not used now,
+and will be rejected by the verifier.
+.TP
+.B Return
+The number of loops performed, \fB\-EINVAL\fP for invalid \fBflags\fP,
+\fB\-E2BIG\fP if \fBnr_loops\fP exceeds the maximum number of loops.
+.UNINDENT
+.TP
+.B \fBlong bpf_strncmp(const char *\fP\fIs1\fP\fB, u32\fP \fIs1_sz\fP\fB, const char *\fP\fIs2\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Do strncmp() between \fBs1\fP and \fBs2\fP\&. \fBs1\fP doesn\(aqt need
+to be null\-terminated and \fBs1_sz\fP is the maximum storage
+size of \fBs1\fP\&. \fBs2\fP must be a read\-only string.
+.TP
+.B Return
+An integer less than, equal to, or greater than zero
+if the first \fBs1_sz\fP bytes of \fBs1\fP is found to be
+less than, to match, or be greater than \fBs2\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_func_arg(void *\fP\fIctx\fP\fB, u32\fP \fIn\fP\fB, u64 *\fP\fIvalue\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get \fBn\fP\-th argument register (zero based) of the traced function (for tracing programs)
+returned in \fBvalue\fP\&.
+.TP
+.B Return
+0 on success.
+\fB\-EINVAL\fP if n >= argument register count of traced function.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_func_ret(void *\fP\fIctx\fP\fB, u64 *\fP\fIvalue\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get return value of the traced function (for tracing programs)
+in \fBvalue\fP\&.
+.TP
+.B Return
+0 on success.
+\fB\-EOPNOTSUPP\fP for tracing programs other than BPF_TRACE_FEXIT or BPF_MODIFY_RETURN.
+.UNINDENT
+.TP
+.B \fBlong bpf_get_func_arg_cnt(void *\fP\fIctx\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get number of registers of the traced function (for tracing programs) where
+function arguments are stored in these registers.
+.TP
+.B Return
+The number of argument registers of the traced function.
+.UNINDENT
+.TP
+.B \fBint bpf_get_retval(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the BPF program\(aqs return value that will be returned to the upper layers.
+.sp
+This helper is currently supported by cgroup programs and only by the hooks
+where BPF program\(aqs return value is returned to the userspace via errno.
+.TP
+.B Return
+The BPF program\(aqs return value.
+.UNINDENT
+.TP
+.B \fBint bpf_set_retval(int\fP \fIretval\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Set the BPF program\(aqs return value that will be returned to the upper layers.
+.sp
+This helper is currently supported by cgroup programs and only by the hooks
+where BPF program\(aqs return value is returned to the userspace via errno.
+.sp
+Note that there is the following corner case where the program exports an error
+via bpf_set_retval but signals success via \(aqreturn 1\(aq:
+.INDENT 7.0
+.INDENT 3.5
+bpf_set_retval(\-EPERM);
+return 1;
+.UNINDENT
+.UNINDENT
+.sp
+In this case, the BPF program\(aqs return value will use helper\(aqs \-EPERM. This
+still holds true for cgroup/bind{4,6} which supports extra \(aqreturn 3\(aq success case.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBu64 bpf_xdp_get_buff_len(struct xdp_buff *\fP\fIxdp_md\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get the total size of a given xdp buff (linear and paged area)
+.TP
+.B Return
+The total size of a given xdp buffer.
+.UNINDENT
+.TP
+.B \fBlong bpf_xdp_load_bytes(struct xdp_buff *\fP\fIxdp_md\fP\fB, u32\fP \fIoffset\fP\fB, void *\fP\fIbuf\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+This helper is provided as an easy way to load data from a
+xdp buffer. It can be used to load \fIlen\fP bytes from \fIoffset\fP from
+the frame associated to \fIxdp_md\fP, into the buffer pointed by
+\fIbuf\fP\&.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_xdp_store_bytes(struct xdp_buff *\fP\fIxdp_md\fP\fB, u32\fP \fIoffset\fP\fB, void *\fP\fIbuf\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Store \fIlen\fP bytes from buffer \fIbuf\fP into the frame
+associated to \fIxdp_md\fP, at \fIoffset\fP\&.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBlong bpf_copy_from_user_task(void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB, const void *\fP\fIuser_ptr\fP\fB, struct task_struct *\fP\fItsk\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Read \fIsize\fP bytes from user space address \fIuser_ptr\fP in \fItsk\fP\(aqs
+address space, and stores the data in \fIdst\fP\&. \fIflags\fP is not
+used yet and is provided for future extensibility. This helper
+can only be used by sleepable programs.
+.TP
+.B Return
+0 on success, or a negative error in case of failure. On error
+\fIdst\fP buffer is zeroed out.
+.UNINDENT
+.TP
+.B \fBlong bpf_skb_set_tstamp(struct sk_buff *\fP\fIskb\fP\fB, u64\fP \fItstamp\fP\fB, u32\fP \fItstamp_type\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Change the __sk_buff\->tstamp_type to \fItstamp_type\fP
+and set \fItstamp\fP to the __sk_buff\->tstamp together.
+.sp
+If there is no need to change the __sk_buff\->tstamp_type,
+the tstamp value can be directly written to __sk_buff\->tstamp
+instead.
+.sp
+BPF_SKB_TSTAMP_DELIVERY_MONO is the only tstamp that
+will be kept during bpf_redirect_*().  A non zero
+\fItstamp\fP must be used with the BPF_SKB_TSTAMP_DELIVERY_MONO
+\fItstamp_type\fP\&.
+.sp
+A BPF_SKB_TSTAMP_UNSPEC \fItstamp_type\fP can only be used
+with a zero \fItstamp\fP\&.
+.sp
+Only IPv4 and IPv6 skb\->protocol are supported.
+.sp
+This function is most useful when it needs to set a
+mono delivery time to __sk_buff\->tstamp and then
+bpf_redirect_*() to the egress of an iface.  For example,
+changing the (rcv) timestamp in __sk_buff\->tstamp at
+ingress to a mono delivery time and then bpf_redirect_*()
+to \fI\%sch_fq@phy\-dev\fP\&.
+.TP
+.B Return
+0 on success.
+\fB\-EINVAL\fP for invalid input
+\fB\-EOPNOTSUPP\fP for unsupported protocol
+.UNINDENT
+.TP
+.B \fBlong bpf_ima_file_hash(struct file *\fP\fIfile\fP\fB, void *\fP\fIdst\fP\fB, u32\fP \fIsize\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Returns a calculated IMA hash of the \fIfile\fP\&.
+If the hash is larger than \fIsize\fP, then only \fIsize\fP
+bytes will be copied to \fIdst\fP
+.TP
+.B Return
+The \fBhash_algo\fP is returned on success,
+\fB\-EOPNOTSUP\fP if the hash calculation failed or \fB\-EINVAL\fP if
+invalid arguments are passed.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_kptr_xchg(void *\fP\fImap_value\fP\fB, void *\fP\fIptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Exchange kptr at pointer \fImap_value\fP with \fIptr\fP, and return the
+old value. \fIptr\fP can be NULL, otherwise it must be a referenced
+pointer which will be released when this helper is called.
+.TP
+.B Return
+The old value of kptr (which can be NULL). The returned pointer
+if not NULL, is a reference which must be released using its
+corresponding release function, or moved into a BPF map before
+program exit.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_map_lookup_percpu_elem(struct bpf_map *\fP\fImap\fP\fB, const void *\fP\fIkey\fP\fB, u32\fP \fIcpu\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Perform a lookup in \fIpercpu map\fP for an entry associated to
+\fIkey\fP on \fIcpu\fP\&.
+.TP
+.B Return
+Map value associated to \fIkey\fP on \fIcpu\fP, or \fBNULL\fP if no entry
+was found or \fIcpu\fP is invalid.
+.UNINDENT
+.TP
+.B \fBstruct mptcp_sock *bpf_skc_to_mptcp_sock(void *\fP\fIsk\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Dynamically cast a \fIsk\fP pointer to a \fImptcp_sock\fP pointer.
+.TP
+.B Return
+\fIsk\fP if casting is valid, or \fBNULL\fP otherwise.
+.UNINDENT
+.TP
+.B \fBlong bpf_dynptr_from_mem(void *\fP\fIdata\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB, struct bpf_dynptr *\fP\fIptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get a dynptr to local memory \fIdata\fP\&.
+.sp
+\fIdata\fP must be a ptr to a map value.
+The maximum \fIsize\fP supported is DYNPTR_MAX_SIZE.
+\fIflags\fP is currently unused.
+.TP
+.B Return
+0 on success, \-E2BIG if the size exceeds DYNPTR_MAX_SIZE,
+\-EINVAL if flags is not 0.
+.UNINDENT
+.TP
+.B \fBlong bpf_ringbuf_reserve_dynptr(void *\fP\fIringbuf\fP\fB, u32\fP \fIsize\fP\fB, u64\fP \fIflags\fP\fB, struct bpf_dynptr *\fP\fIptr\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Reserve \fIsize\fP bytes of payload in a ring buffer \fIringbuf\fP
+through the dynptr interface. \fIflags\fP must be 0.
+.sp
+Please note that a corresponding bpf_ringbuf_submit_dynptr or
+bpf_ringbuf_discard_dynptr must be called on \fIptr\fP, even if the
+reservation fails. This is enforced by the verifier.
+.TP
+.B Return
+0 on success, or a negative error in case of failure.
+.UNINDENT
+.TP
+.B \fBvoid bpf_ringbuf_submit_dynptr(struct bpf_dynptr *\fP\fIptr\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Submit reserved ring buffer sample, pointed to by \fIdata\fP,
+through the dynptr interface. This is a no\-op if the dynptr is
+invalid/null.
+.sp
+For more information on \fIflags\fP, please see
+\(aqbpf_ringbuf_submit\(aq.
+.TP
+.B Return
+Nothing. Always succeeds.
+.UNINDENT
+.TP
+.B \fBvoid bpf_ringbuf_discard_dynptr(struct bpf_dynptr *\fP\fIptr\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Discard reserved ring buffer sample through the dynptr
+interface. This is a no\-op if the dynptr is invalid/null.
+.sp
+For more information on \fIflags\fP, please see
+\(aqbpf_ringbuf_discard\(aq.
+.TP
+.B Return
+Nothing. Always succeeds.
+.UNINDENT
+.TP
+.B \fBlong bpf_dynptr_read(void *\fP\fIdst\fP\fB, u32\fP \fIlen\fP\fB, const struct bpf_dynptr *\fP\fIsrc\fP\fB, u32\fP \fIoffset\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Read \fIlen\fP bytes from \fIsrc\fP into \fIdst\fP, starting from \fIoffset\fP
+into \fIsrc\fP\&.
+\fIflags\fP is currently unused.
+.TP
+.B Return
+0 on success, \-E2BIG if \fIoffset\fP + \fIlen\fP exceeds the length
+of \fIsrc\fP\(aqs data, \-EINVAL if \fIsrc\fP is an invalid dynptr or if
+\fIflags\fP is not 0.
+.UNINDENT
+.TP
+.B \fBlong bpf_dynptr_write(const struct bpf_dynptr *\fP\fIdst\fP\fB, u32\fP \fIoffset\fP\fB, void *\fP\fIsrc\fP\fB, u32\fP \fIlen\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Write \fIlen\fP bytes from \fIsrc\fP into \fIdst\fP, starting from \fIoffset\fP
+into \fIdst\fP\&.
+.sp
+\fIflags\fP must be 0 except for skb\-type dynptrs.
+.INDENT 7.0
+.TP
+.B For skb\-type dynptrs:
+.INDENT 7.0
+.IP \(bu 2
+All data slices of the dynptr are automatically
+invalidated after \fBbpf_dynptr_write\fP(). This is
+because writing may pull the skb and change the
+underlying packet buffer.
+.IP \(bu 2
+For \fIflags\fP, please see the flags accepted by
+\fBbpf_skb_store_bytes\fP().
+.UNINDENT
+.UNINDENT
+.TP
+.B Return
+0 on success, \-E2BIG if \fIoffset\fP + \fIlen\fP exceeds the length
+of \fIdst\fP\(aqs data, \-EINVAL if \fIdst\fP is an invalid dynptr or if \fIdst\fP
+is a read\-only dynptr or if \fIflags\fP is not correct. For skb\-type dynptrs,
+other errors correspond to errors returned by \fBbpf_skb_store_bytes\fP().
+.UNINDENT
+.TP
+.B \fBvoid *bpf_dynptr_data(const struct bpf_dynptr *\fP\fIptr\fP\fB, u32\fP \fIoffset\fP\fB, u32\fP \fIlen\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get a pointer to the underlying dynptr data.
+.sp
+\fIlen\fP must be a statically known value. The returned data slice
+is invalidated whenever the dynptr is invalidated.
+.sp
+skb and xdp type dynptrs may not use bpf_dynptr_data. They should
+instead use bpf_dynptr_slice and bpf_dynptr_slice_rdwr.
+.TP
+.B Return
+Pointer to the underlying dynptr data, NULL if the dynptr is
+read\-only, if the dynptr is invalid, or if the offset and length
+is out of bounds.
+.UNINDENT
+.TP
+.B \fBs64 bpf_tcp_raw_gen_syncookie_ipv4(struct iphdr *\fP\fIiph\fP\fB, struct tcphdr *\fP\fIth\fP\fB, u32\fP \fIth_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Try to issue a SYN cookie for the packet with corresponding
+IPv4/TCP headers, \fIiph\fP and \fIth\fP, without depending on a
+listening socket.
+.sp
+\fIiph\fP points to the IPv4 header.
+.sp
+\fIth\fP points to the start of the TCP header, while \fIth_len\fP
+contains the length of the TCP header (at least
+\fBsizeof\fP(\fBstruct tcphdr\fP)).
+.TP
+.B Return
+On success, lower 32 bits hold the generated SYN cookie in
+followed by 16 bits which hold the MSS value for that cookie,
+and the top 16 bits are unused.
+.sp
+On failure, the returned value is one of the following:
+.sp
+\fB\-EINVAL\fP if \fIth_len\fP is invalid.
+.UNINDENT
+.TP
+.B \fBs64 bpf_tcp_raw_gen_syncookie_ipv6(struct ipv6hdr *\fP\fIiph\fP\fB, struct tcphdr *\fP\fIth\fP\fB, u32\fP \fIth_len\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Try to issue a SYN cookie for the packet with corresponding
+IPv6/TCP headers, \fIiph\fP and \fIth\fP, without depending on a
+listening socket.
+.sp
+\fIiph\fP points to the IPv6 header.
+.sp
+\fIth\fP points to the start of the TCP header, while \fIth_len\fP
+contains the length of the TCP header (at least
+\fBsizeof\fP(\fBstruct tcphdr\fP)).
+.TP
+.B Return
+On success, lower 32 bits hold the generated SYN cookie in
+followed by 16 bits which hold the MSS value for that cookie,
+and the top 16 bits are unused.
+.sp
+On failure, the returned value is one of the following:
+.sp
+\fB\-EINVAL\fP if \fIth_len\fP is invalid.
+.sp
+\fB\-EPROTONOSUPPORT\fP if CONFIG_IPV6 is not builtin.
+.UNINDENT
+.TP
+.B \fBlong bpf_tcp_raw_check_syncookie_ipv4(struct iphdr *\fP\fIiph\fP\fB, struct tcphdr *\fP\fIth\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Check whether \fIiph\fP and \fIth\fP contain a valid SYN cookie ACK
+without depending on a listening socket.
+.sp
+\fIiph\fP points to the IPv4 header.
+.sp
+\fIth\fP points to the TCP header.
+.TP
+.B Return
+0 if \fIiph\fP and \fIth\fP are a valid SYN cookie ACK.
+.sp
+On failure, the returned value is one of the following:
+.sp
+\fB\-EACCES\fP if the SYN cookie is not valid.
+.UNINDENT
+.TP
+.B \fBlong bpf_tcp_raw_check_syncookie_ipv6(struct ipv6hdr *\fP\fIiph\fP\fB, struct tcphdr *\fP\fIth\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Check whether \fIiph\fP and \fIth\fP contain a valid SYN cookie ACK
+without depending on a listening socket.
+.sp
+\fIiph\fP points to the IPv6 header.
+.sp
+\fIth\fP points to the TCP header.
+.TP
+.B Return
+0 if \fIiph\fP and \fIth\fP are a valid SYN cookie ACK.
+.sp
+On failure, the returned value is one of the following:
+.sp
+\fB\-EACCES\fP if the SYN cookie is not valid.
+.sp
+\fB\-EPROTONOSUPPORT\fP if CONFIG_IPV6 is not builtin.
+.UNINDENT
+.TP
+.B \fBu64 bpf_ktime_get_tai_ns(void)\fP
+.INDENT 7.0
+.TP
+.B Description
+A nonsettable system\-wide clock derived from wall\-clock time but
+ignoring leap seconds.  This clock does not experience
+discontinuities and backwards jumps caused by NTP inserting leap
+seconds as CLOCK_REALTIME does.
+.sp
+See: \fBclock_gettime\fP(\fBCLOCK_TAI\fP)
+.TP
+.B Return
+Current \fIktime\fP\&.
+.UNINDENT
+.TP
+.B \fBlong bpf_user_ringbuf_drain(struct bpf_map *\fP\fImap\fP\fB, void *\fP\fIcallback_fn\fP\fB, void *\fP\fIctx\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Drain samples from the specified user ring buffer, and invoke
+the provided callback for each such sample:
+.sp
+long (*callback_fn)(const struct bpf_dynptr *dynptr, void *ctx);
+.sp
+If \fBcallback_fn\fP returns 0, the helper will continue to try
+and drain the next sample, up to a maximum of
+BPF_MAX_USER_RINGBUF_SAMPLES samples. If the return value is 1,
+the helper will skip the rest of the samples and return. Other
+return values are not used now, and will be rejected by the
+verifier.
+.TP
+.B Return
+The number of drained samples if no error was encountered while
+draining samples, or 0 if no samples were present in the ring
+buffer. If a user\-space producer was epoll\-waiting on this map,
+and at least one sample was drained, they will receive an event
+notification notifying them of available space in the ring
+buffer. If the BPF_RB_NO_WAKEUP flag is passed to this
+function, no wakeup notification will be sent. If the
+BPF_RB_FORCE_WAKEUP flag is passed, a wakeup notification will
+be sent even if no sample was drained.
+.sp
+On failure, the returned value is one of the following:
+.sp
+\fB\-EBUSY\fP if the ring buffer is contended, and another calling
+context was concurrently draining the ring buffer.
+.sp
+\fB\-EINVAL\fP if user\-space is not properly tracking the ring
+buffer due to the producer position not being aligned to 8
+bytes, a sample not being aligned to 8 bytes, or the producer
+position not matching the advertised length of a sample.
+.sp
+\fB\-E2BIG\fP if user\-space has tried to publish a sample which is
+larger than the size of the ring buffer, or which cannot fit
+within a struct bpf_dynptr.
+.UNINDENT
+.TP
+.B \fBvoid *bpf_cgrp_storage_get(struct bpf_map *\fP\fImap\fP\fB, struct cgroup *\fP\fIcgroup\fP\fB, void *\fP\fIvalue\fP\fB, u64\fP \fIflags\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Get a bpf_local_storage from the \fIcgroup\fP\&.
+.sp
+Logically, it could be thought of as getting the value from
+a \fImap\fP with \fIcgroup\fP as the \fBkey\fP\&.  From this
+perspective,  the usage is not much different from
+\fBbpf_map_lookup_elem\fP(\fImap\fP, \fB&\fP\fIcgroup\fP) except this
+helper enforces the key must be a cgroup struct and the map must also
+be a \fBBPF_MAP_TYPE_CGRP_STORAGE\fP\&.
+.sp
+In reality, the local\-storage value is embedded directly inside of the
+\fIcgroup\fP object itself, rather than being located in the
+\fBBPF_MAP_TYPE_CGRP_STORAGE\fP map. When the local\-storage value is
+queried for some \fImap\fP on a \fIcgroup\fP object, the kernel will perform an
+O(n) iteration over all of the live local\-storage values for that
+\fIcgroup\fP object until the local\-storage value for the \fImap\fP is found.
+.sp
+An optional \fIflags\fP (\fBBPF_LOCAL_STORAGE_GET_F_CREATE\fP) can be
+used such that a new bpf_local_storage will be
+created if one does not exist.  \fIvalue\fP can be used
+together with \fBBPF_LOCAL_STORAGE_GET_F_CREATE\fP to specify
+the initial value of a bpf_local_storage.  If \fIvalue\fP is
+\fBNULL\fP, the new bpf_local_storage will be zero initialized.
+.TP
+.B Return
+A bpf_local_storage pointer is returned on success.
+.sp
+\fBNULL\fP if not found or there was an error in adding
+a new bpf_local_storage.
+.UNINDENT
+.TP
+.B \fBlong bpf_cgrp_storage_delete(struct bpf_map *\fP\fImap\fP\fB, struct cgroup *\fP\fIcgroup\fP\fB)\fP
+.INDENT 7.0
+.TP
+.B Description
+Delete a bpf_local_storage from a \fIcgroup\fP\&.
+.TP
+.B Return
+0 on success.
+.sp
+\fB\-ENOENT\fP if the bpf_local_storage cannot be found.
+.UNINDENT
+.UNINDENT
+.SH EXAMPLES
+.sp
+Example usage for most of the eBPF helpers listed in this manual page are
+available within the Linux kernel sources, at the following locations:
+.INDENT 0.0
+.IP \(bu 2
+\fIsamples/bpf/\fP
+.IP \(bu 2
+\fItools/testing/selftests/bpf/\fP
+.UNINDENT
+.SH LICENSE
+.sp
+eBPF programs can have an associated license, passed along with the bytecode
+instructions to the kernel when the programs are loaded. The format for that
+string is identical to the one in use for kernel modules (Dual licenses, such
+as \(dqDual BSD/GPL\(dq, may be used). Some helper functions are only accessible to
+programs that are compatible with the GNU General Public License (GNU GPL).
+.sp
+In order to use such helpers, the eBPF program must be loaded with the correct
+license string passed (via \fBattr\fP) to the \fBbpf\fP() system call, and this
+generally translates into the C source code of the program containing a line
+similar to the following:
+.INDENT 0.0
+.INDENT 3.5
+.sp
+.EX
+char ____license[] __attribute__((section(\(dqlicense\(dq), used)) = \(dqGPL\(dq;
+.EE
+.UNINDENT
+.UNINDENT
+.SH IMPLEMENTATION
+.sp
+This manual page is an effort to document the existing eBPF helper functions.
+But as of this writing, the BPF sub\-system is under heavy development. New eBPF
+program or map types are added, along with new helper functions. Some helpers
+are occasionally made available for additional program types. So in spite of
+the efforts of the community, this page might not be up\-to\-date. If you want to
+check by yourself what helper functions exist in your kernel, or what types of
+programs they can support, here are some files among the kernel tree that you
+may be interested in:
+.INDENT 0.0
+.IP \(bu 2
+\fIinclude/uapi/linux/bpf.h\fP is the main BPF header. It contains the full list
+of all helper functions, as well as many other BPF definitions including most
+of the flags, structs or constants used by the helpers.
+.IP \(bu 2
+\fInet/core/filter.c\fP contains the definition of most network\-related helper
+functions, and the list of program types from which they can be used.
+.IP \(bu 2
+\fIkernel/trace/bpf_trace.c\fP is the equivalent for most tracing program\-related
+helpers.
+.IP \(bu 2
+\fIkernel/bpf/verifier.c\fP contains the functions used to check that valid types
+of eBPF maps are used with a given helper function.
+.IP \(bu 2
+\fIkernel/bpf/\fP directory contains other files in which additional helpers are
+defined (for cgroups, sockmaps, etc.).
+.IP \(bu 2
+The bpftool utility can be used to probe the availability of helper functions
+on the system (as well as supported program and map types, and a number of
+other parameters). To do so, run \fBbpftool feature probe\fP (see
+\fBbpftool\-feature\fP(8) for details). Add the \fBunprivileged\fP keyword to
+list features available to unprivileged users.
+.UNINDENT
+.sp
+Compatibility between helper functions and program types can generally be found
+in the files where helper functions are defined. Look for the \fBstruct
+bpf_func_proto\fP objects and for functions returning them: these functions
+contain a list of helpers that a given program type can call. Note that the
+\fBdefault:\fP label of the \fBswitch ... case\fP used to filter helpers can call
+other functions, themselves allowing access to additional helpers. The
+requirement for GPL license is also in those \fBstruct bpf_func_proto\fP\&.
+.sp
+Compatibility between helper functions and map types can be found in the
+\fBcheck_map_func_compatibility\fP() function in file \fIkernel/bpf/verifier.c\fP\&.
+.sp
+Helper functions that invalidate the checks on \fBdata\fP and \fBdata_end\fP
+pointers for network processing are listed in function
+\fBbpf_helper_changes_pkt_data\fP() in file \fInet/core/filter.c\fP\&.
+.SH SEE ALSO
+.sp
+\fBbpf\fP(2),
+\fBbpftool\fP(8),
+\fBcgroups\fP(7),
+\fBip\fP(8),
+\fBperf_event_open\fP(2),
+\fBsendmsg\fP(2),
+\fBsocket\fP(7),
+\fBtc\-bpf\fP(8)
+.\" Generated by docutils manpage writer.
+.
diff --git a/man/man7/capabilities.7 b/man/man7/capabilities.7
new file mode 100644
index 000000000..b86ef7af0
--- /dev/null
+++ b/man/man7/capabilities.7
@@ -0,0 +1,1872 @@
+.\" Copyright (c) 2002 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 6 Aug 2002 - Initial Creation
+.\" Modified 2003-05-23, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\" Modified 2004-05-27, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\" 2004-12-08, mtk Added O_NOATIME for CAP_FOWNER
+.\" 2005-08-16, mtk, Added CAP_AUDIT_CONTROL and CAP_AUDIT_WRITE
+.\" 2008-07-15, Serge Hallyn <serue@us.bbm.com>
+.\"     Document file capabilities, per-process capability
+.\"     bounding set, changed semantics for CAP_SETPCAP,
+.\"     and other changes in Linux 2.6.2[45].
+.\"     Add CAP_MAC_ADMIN, CAP_MAC_OVERRIDE, CAP_SETFCAP.
+.\" 2008-07-15, mtk
+.\"     Add text describing circumstances in which CAP_SETPCAP
+.\"     (theoretically) permits a thread to change the
+.\"     capability sets of another thread.
+.\"     Add section describing rules for programmatically
+.\"     adjusting thread capability sets.
+.\"     Describe rationale for capability bounding set.
+.\"     Document "securebits" flags.
+.\"     Add text noting that if we set the effective flag for one file
+.\"     capability, then we must also set the effective flag for all
+.\"     other capabilities where the permitted or inheritable bit is set.
+.\" 2011-09-07, mtk/Serge hallyn: Add CAP_SYSLOG
+.\"
+.TH Capabilities 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+capabilities \- overview of Linux capabilities
+.SH DESCRIPTION
+For the purpose of performing permission checks,
+traditional UNIX implementations distinguish two categories of processes:
+.I privileged
+processes (whose effective user ID is 0, referred to as superuser or root),
+and
+.I unprivileged
+processes (whose effective UID is nonzero).
+Privileged processes bypass all kernel permission checks,
+while unprivileged processes are subject to full permission
+checking based on the process's credentials
+(usually: effective UID, effective GID, and supplementary group list).
+.P
+Starting with Linux 2.2, Linux divides the privileges traditionally
+associated with superuser into distinct units, known as
+.IR capabilities ,
+which can be independently enabled and disabled.
+Capabilities are a per-thread attribute.
+.\"
+.SS Capabilities list
+The following list shows the capabilities implemented on Linux,
+and the operations or behaviors that each capability permits:
+.TP
+.BR CAP_AUDIT_CONTROL " (since Linux 2.6.11)"
+Enable and disable kernel auditing; change auditing filter rules;
+retrieve auditing status and filtering rules.
+.TP
+.BR CAP_AUDIT_READ " (since Linux 3.16)"
+.\" commit a29b694aa1739f9d76538e34ae25524f9c549d59
+.\" commit 3a101b8de0d39403b2c7e5c23fd0b005668acf48
+Allow reading the audit log via a multicast netlink socket.
+.TP
+.BR CAP_AUDIT_WRITE " (since Linux 2.6.11)"
+Write records to kernel auditing log.
+.\" FIXME Add FAN_ENABLE_AUDIT
+.TP
+.BR CAP_BLOCK_SUSPEND " (since Linux 3.5)"
+Employ features that can block system suspend
+.RB ( epoll (7)
+.BR EPOLLWAKEUP ,
+.IR /proc/sys/wake_lock ).
+.TP
+.BR CAP_BPF " (since Linux 5.8)"
+Employ privileged BPF operations; see
+.BR bpf (2)
+and
+.BR bpf\-helpers (7).
+.IP
+This capability was added in Linux 5.8 to separate out
+BPF functionality from the overloaded
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.BR CAP_CHECKPOINT_RESTORE " (since Linux 5.9)"
+.\" commit 124ea650d3072b005457faed69909221c2905a1f
+.PD 0
+.RS
+.IP \[bu] 3
+Update
+.I /proc/sys/kernel/ns_last_pid
+(see
+.BR pid_namespaces (7));
+.IP \[bu]
+employ the
+.I set_tid
+feature of
+.BR clone3 (2);
+.\" FIXME There is also some use case relating to
+.\" prctl_set_mm_exe_file(); in the 5.9 sources, see
+.\" prctl_set_mm_map().
+.IP \[bu]
+read the contents of the symbolic links in
+.IR /proc/ pid /map_files
+for other processes.
+.RE
+.PD
+.IP
+This capability was added in Linux 5.9 to separate out
+checkpoint/restore functionality from the overloaded
+.B CAP_SYS_ADMIN
+capability.
+.TP
+.B CAP_CHOWN
+Make arbitrary changes to file UIDs and GIDs (see
+.BR chown (2)).
+.TP
+.B CAP_DAC_OVERRIDE
+Bypass file read, write, and execute permission checks.
+(DAC is an abbreviation of "discretionary access control".)
+.TP
+.B CAP_DAC_READ_SEARCH
+.PD 0
+.RS
+.IP \[bu] 3
+Bypass file read permission checks and
+directory read and execute permission checks;
+.IP \[bu]
+invoke
+.BR open_by_handle_at (2);
+.IP \[bu]
+use the
+.BR linkat (2)
+.B AT_EMPTY_PATH
+flag to create a link to a file referred to by a file descriptor.
+.RE
+.PD
+.TP
+.B CAP_FOWNER
+.PD 0
+.RS
+.IP \[bu] 3
+Bypass permission checks on operations that normally
+require the filesystem UID of the process to match the UID of
+the file (e.g.,
+.BR chmod (2),
+.BR utime (2)),
+excluding those operations covered by
+.B CAP_DAC_OVERRIDE
+and
+.BR CAP_DAC_READ_SEARCH ;
+.IP \[bu]
+set inode flags (see
+.BR ioctl_iflags (2))
+on arbitrary files;
+.IP \[bu]
+set Access Control Lists (ACLs) on arbitrary files;
+.IP \[bu]
+ignore directory sticky bit on file deletion;
+.IP \[bu]
+modify
+.I user
+extended attributes on sticky directory owned by any user;
+.IP \[bu]
+specify
+.B O_NOATIME
+for arbitrary files in
+.BR open (2)
+and
+.BR fcntl (2).
+.RE
+.PD
+.TP
+.B CAP_FSETID
+.PD 0
+.RS
+.IP \[bu] 3
+Don't clear set-user-ID and set-group-ID mode
+bits when a file is modified;
+.IP \[bu]
+set the set-group-ID bit for a file whose GID does not match
+the filesystem or any of the supplementary GIDs of the calling process.
+.RE
+.PD
+.TP
+.B CAP_IPC_LOCK
+.\" FIXME . As at Linux 3.2, there are some strange uses of this capability
+.\" in other places; they probably should be replaced with something else.
+.PD 0
+.RS
+.IP \[bu] 3
+Lock memory
+.RB ( mlock (2),
+.BR mlockall (2),
+.BR mmap (2),
+.BR shmctl (2));
+.IP \[bu]
+Allocate memory using huge pages
+.RB ( memfd_create (2),
+.BR mmap (2),
+.BR shmctl (2)).
+.RE
+.PD
+.TP
+.B CAP_IPC_OWNER
+Bypass permission checks for operations on System V IPC objects.
+.TP
+.B CAP_KILL
+Bypass permission checks for sending signals (see
+.BR kill (2)).
+This includes use of the
+.BR ioctl (2)
+.B KDSIGACCEPT
+operation.
+.\" FIXME . CAP_KILL also has an effect for threads + setting child
+.\"       termination signal to other than SIGCHLD: without this
+.\"       capability, the termination signal reverts to SIGCHLD
+.\"       if the child does an exec().  What is the rationale
+.\"       for this?
+.TP
+.BR CAP_LEASE " (since Linux 2.4)"
+Establish leases on arbitrary files (see
+.BR fcntl (2)).
+.TP
+.B CAP_LINUX_IMMUTABLE
+Set the
+.B FS_APPEND_FL
+and
+.B FS_IMMUTABLE_FL
+inode flags (see
+.BR ioctl_iflags (2)).
+.TP
+.BR CAP_MAC_ADMIN " (since Linux 2.6.25)"
+Allow MAC configuration or state changes.
+Implemented for the Smack Linux Security Module (LSM).
+.TP
+.BR CAP_MAC_OVERRIDE " (since Linux 2.6.25)"
+Override Mandatory Access Control (MAC).
+Implemented for the Smack LSM.
+.TP
+.BR CAP_MKNOD " (since Linux 2.4)"
+Create special files using
+.BR mknod (2).
+.TP
+.B CAP_NET_ADMIN
+Perform various network-related operations:
+.PD 0
+.RS
+.IP \[bu] 3
+interface configuration;
+.IP \[bu]
+administration of IP firewall, masquerading, and accounting;
+.IP \[bu]
+modify routing tables;
+.IP \[bu]
+bind to any address for transparent proxying;
+.IP \[bu]
+set type-of-service (TOS);
+.IP \[bu]
+clear driver statistics;
+.IP \[bu]
+set promiscuous mode;
+.IP \[bu]
+enabling multicasting;
+.IP \[bu]
+use
+.BR setsockopt (2)
+to set the following socket options:
+.BR SO_DEBUG ,
+.BR SO_MARK ,
+.B SO_PRIORITY
+(for a priority outside the range 0 to 6),
+.BR SO_RCVBUFFORCE ,
+and
+.BR SO_SNDBUFFORCE .
+.RE
+.PD
+.TP
+.B CAP_NET_BIND_SERVICE
+Bind a socket to Internet domain privileged ports
+(port numbers less than 1024).
+.TP
+.B CAP_NET_BROADCAST
+(Unused)  Make socket broadcasts, and listen to multicasts.
+.\" FIXME Since Linux 4.2, there are use cases for netlink sockets
+.\"    commit 59324cf35aba5336b611074028777838a963d03b
+.TP
+.B CAP_NET_RAW
+.PD 0
+.RS
+.IP \[bu] 3
+Use RAW and PACKET sockets;
+.IP \[bu]
+bind to any address for transparent proxying.
+.RE
+.PD
+.\" Also various IP options and setsockopt(SO_BINDTODEVICE)
+.TP
+.BR CAP_PERFMON " (since Linux 5.8)"
+Employ various performance-monitoring mechanisms, including:
+.RS
+.IP \[bu] 3
+.PD 0
+call
+.BR perf_event_open (2);
+.IP \[bu]
+employ various BPF operations that have performance implications.
+.RE
+.PD
+.IP
+This capability was added in Linux 5.8 to separate out
+performance monitoring functionality from the overloaded
+.B CAP_SYS_ADMIN
+capability.
+See also the kernel source file
+.IR Documentation/admin\-guide/perf\-security.rst .
+.TP
+.B CAP_SETGID
+.RS
+.PD 0
+.IP \[bu] 3
+Make arbitrary manipulations of process GIDs and supplementary GID list;
+.IP \[bu]
+forge GID when passing socket credentials via UNIX domain sockets;
+.IP \[bu]
+write a group ID mapping in a user namespace (see
+.BR user_namespaces (7)).
+.PD
+.RE
+.TP
+.BR CAP_SETFCAP " (since Linux 2.6.24)"
+Set arbitrary capabilities on a file.
+.IP
+.\" commit db2e718a47984b9d71ed890eb2ea36ecf150de18
+Since Linux 5.12, this capability is
+also needed to map user ID 0 in a new user namespace; see
+.BR user_namespaces (7)
+for details.
+.TP
+.B CAP_SETPCAP
+If file capabilities are supported (i.e., since Linux 2.6.24):
+add any capability from the calling thread's bounding set
+to its inheritable set;
+drop capabilities from the bounding set (via
+.BR prctl (2)
+.BR PR_CAPBSET_DROP );
+make changes to the
+.I securebits
+flags.
+.IP
+If file capabilities are not supported (i.e., before Linux 2.6.24):
+grant or remove any capability in the
+caller's permitted capability set to or from any other process.
+(This property of
+.B CAP_SETPCAP
+is not available when the kernel is configured to support
+file capabilities, since
+.B CAP_SETPCAP
+has entirely different semantics for such kernels.)
+.TP
+.B CAP_SETUID
+.RS
+.PD 0
+.IP \[bu] 3
+Make arbitrary manipulations of process UIDs
+.RB ( setuid (2),
+.BR setreuid (2),
+.BR setresuid (2),
+.BR setfsuid (2));
+.IP \[bu]
+forge UID when passing socket credentials via UNIX domain sockets;
+.IP \[bu]
+write a user ID mapping in a user namespace (see
+.BR user_namespaces (7)).
+.PD
+.RE
+.\" FIXME CAP_SETUID also an effect in exec(); document this.
+.TP
+.B CAP_SYS_ADMIN
+.IR Note :
+this capability is overloaded; see
+.I Notes to kernel developers
+below.
+.IP
+.PD 0
+.RS
+.IP \[bu] 3
+Perform a range of system administration operations including:
+.BR quotactl (2),
+.BR mount (2),
+.BR umount (2),
+.BR pivot_root (2),
+.BR swapon (2),
+.BR swapoff (2),
+.BR sethostname (2),
+and
+.BR setdomainname (2);
+.IP \[bu]
+perform privileged
+.BR syslog (2)
+operations (since Linux 2.6.37,
+.B CAP_SYSLOG
+should be used to permit such operations);
+.IP \[bu]
+perform
+.B VM86_REQUEST_IRQ
+.BR vm86 (2)
+command;
+.IP \[bu]
+access the same checkpoint/restore functionality that is governed by
+.B CAP_CHECKPOINT_RESTORE
+(but the latter, weaker capability is preferred for accessing
+that functionality).
+.IP \[bu]
+perform the same BPF operations as are governed by
+.B CAP_BPF
+(but the latter, weaker capability is preferred for accessing
+that functionality).
+.IP \[bu]
+employ the same performance monitoring mechanisms as are governed by
+.B CAP_PERFMON
+(but the latter, weaker capability is preferred for accessing
+that functionality).
+.IP \[bu]
+perform
+.B IPC_SET
+and
+.B IPC_RMID
+operations on arbitrary System V IPC objects;
+.IP \[bu]
+override
+.B RLIMIT_NPROC
+resource limit;
+.IP \[bu]
+perform operations on
+.I trusted
+and
+.I security
+extended attributes (see
+.BR xattr (7));
+.IP \[bu]
+use
+.BR lookup_dcookie (2);
+.IP \[bu]
+use
+.BR ioprio_set (2)
+to assign
+.B IOPRIO_CLASS_RT
+and (before Linux 2.6.25)
+.B IOPRIO_CLASS_IDLE
+I/O scheduling classes;
+.IP \[bu]
+forge PID when passing socket credentials via UNIX domain sockets;
+.IP \[bu]
+exceed
+.IR /proc/sys/fs/file\-max ,
+the system-wide limit on the number of open files,
+in system calls that open files (e.g.,
+.BR accept (2),
+.BR execve (2),
+.BR open (2),
+.BR pipe (2));
+.IP \[bu]
+employ
+.B CLONE_*
+flags that create new namespaces with
+.BR clone (2)
+and
+.BR unshare (2)
+(but, since Linux 3.8,
+creating user namespaces does not require any capability);
+.IP \[bu]
+access privileged
+.I perf
+event information;
+.IP \[bu]
+call
+.BR setns (2)
+(requires
+.B CAP_SYS_ADMIN
+in the
+.I target
+namespace);
+.IP \[bu]
+call
+.BR fanotify_init (2);
+.IP \[bu]
+perform privileged
+.B KEYCTL_CHOWN
+and
+.B KEYCTL_SETPERM
+.BR keyctl (2)
+operations;
+.IP \[bu]
+perform
+.BR madvise (2)
+.B MADV_HWPOISON
+operation;
+.IP \[bu]
+employ the
+.B TIOCSTI
+.BR ioctl (2)
+to insert characters into the input queue of a terminal other than
+the caller's controlling terminal;
+.IP \[bu]
+employ the obsolete
+.BR nfsservctl (2)
+system call;
+.IP \[bu]
+employ the obsolete
+.BR bdflush (2)
+system call;
+.IP \[bu]
+perform various privileged block-device
+.BR ioctl (2)
+operations;
+.IP \[bu]
+perform various privileged filesystem
+.BR ioctl (2)
+operations;
+.IP \[bu]
+perform privileged
+.BR ioctl (2)
+operations on the
+.I /dev/random
+device (see
+.BR random (4));
+.IP \[bu]
+install a
+.BR seccomp (2)
+filter without first having to set the
+.I no_new_privs
+thread attribute;
+.IP \[bu]
+modify allow/deny rules for device control groups;
+.IP \[bu]
+employ the
+.BR ptrace (2)
+.B PTRACE_SECCOMP_GET_FILTER
+operation to dump tracee's seccomp filters;
+.IP \[bu]
+employ the
+.BR ptrace (2)
+.B PTRACE_SETOPTIONS
+operation to suspend the tracee's seccomp protections (i.e., the
+.B PTRACE_O_SUSPEND_SECCOMP
+flag);
+.IP \[bu]
+perform administrative operations on many device drivers;
+.IP \[bu]
+modify autogroup nice values by writing to
+.IR /proc/ pid /autogroup
+(see
+.BR sched (7)).
+.RE
+.PD
+.TP
+.B CAP_SYS_BOOT
+Use
+.BR reboot (2)
+and
+.BR kexec_load (2).
+.TP
+.B CAP_SYS_CHROOT
+.RS
+.PD 0
+.IP \[bu] 3
+Use
+.BR chroot (2);
+.IP \[bu]
+change mount namespaces using
+.BR setns (2).
+.PD
+.RE
+.TP
+.B CAP_SYS_MODULE
+.RS
+.PD 0
+.IP \[bu] 3
+Load and unload kernel modules
+(see
+.BR init_module (2)
+and
+.BR delete_module (2));
+.IP \[bu]
+before Linux 2.6.25:
+drop capabilities from the system-wide capability bounding set.
+.PD
+.RE
+.TP
+.B CAP_SYS_NICE
+.PD 0
+.RS
+.IP \[bu] 3
+Lower the process nice value
+.RB ( nice (2),
+.BR setpriority (2))
+and change the nice value for arbitrary processes;
+.IP \[bu]
+set real-time scheduling policies for calling process,
+and set scheduling policies and priorities for arbitrary processes
+.RB ( sched_setscheduler (2),
+.BR sched_setparam (2),
+.BR sched_setattr (2));
+.IP \[bu]
+set CPU affinity for arbitrary processes
+.RB ( sched_setaffinity (2));
+.IP \[bu]
+set I/O scheduling class and priority for arbitrary processes
+.RB ( ioprio_set (2));
+.IP \[bu]
+apply
+.BR migrate_pages (2)
+to arbitrary processes and allow processes
+to be migrated to arbitrary nodes;
+.\" FIXME CAP_SYS_NICE also has the following effect for
+.\" migrate_pages(2):
+.\"     do_migrate_pages(mm, &old, &new,
+.\"         capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
+.\"
+.\" Document this.
+.IP \[bu]
+apply
+.BR move_pages (2)
+to arbitrary processes;
+.IP \[bu]
+use the
+.B MPOL_MF_MOVE_ALL
+flag with
+.BR mbind (2)
+and
+.BR move_pages (2).
+.RE
+.PD
+.TP
+.B CAP_SYS_PACCT
+Use
+.BR acct (2).
+.TP
+.B CAP_SYS_PTRACE
+.PD 0
+.RS
+.IP \[bu] 3
+Trace arbitrary processes using
+.BR ptrace (2);
+.IP \[bu]
+apply
+.BR get_robust_list (2)
+to arbitrary processes;
+.IP \[bu]
+transfer data to or from the memory of arbitrary processes using
+.BR process_vm_readv (2)
+and
+.BR process_vm_writev (2);
+.IP \[bu]
+inspect processes using
+.BR kcmp (2).
+.RE
+.PD
+.TP
+.B CAP_SYS_RAWIO
+.PD 0
+.RS
+.IP \[bu] 3
+Perform I/O port operations
+.RB ( iopl (2)
+and
+.BR ioperm (2));
+.IP \[bu]
+access
+.IR /proc/kcore ;
+.IP \[bu]
+employ the
+.B FIBMAP
+.BR ioctl (2)
+operation;
+.IP \[bu]
+open devices for accessing x86 model-specific registers (MSRs, see
+.BR msr (4));
+.IP \[bu]
+update
+.IR /proc/sys/vm/mmap_min_addr ;
+.IP \[bu]
+create memory mappings at addresses below the value specified by
+.IR /proc/sys/vm/mmap_min_addr ;
+.IP \[bu]
+map files in
+.IR /proc/bus/pci ;
+.IP \[bu]
+open
+.I /dev/mem
+and
+.IR /dev/kmem ;
+.IP \[bu]
+perform various SCSI device commands;
+.IP \[bu]
+perform certain operations on
+.BR hpsa (4)
+and
+.BR cciss (4)
+devices;
+.IP \[bu]
+perform a range of device-specific operations on other devices.
+.RE
+.PD
+.TP
+.B CAP_SYS_RESOURCE
+.PD 0
+.RS
+.IP \[bu] 3
+Use reserved space on ext2 filesystems;
+.IP \[bu]
+make
+.BR ioctl (2)
+calls controlling ext3 journaling;
+.IP \[bu]
+override disk quota limits;
+.IP \[bu]
+increase resource limits (see
+.BR setrlimit (2));
+.IP \[bu]
+override
+.B RLIMIT_NPROC
+resource limit;
+.IP \[bu]
+override maximum number of consoles on console allocation;
+.IP \[bu]
+override maximum number of keymaps;
+.IP \[bu]
+allow more than 64hz interrupts from the real-time clock;
+.IP \[bu]
+raise
+.I msg_qbytes
+limit for a System V message queue above the limit in
+.I /proc/sys/kernel/msgmnb
+(see
+.BR msgop (2)
+and
+.BR msgctl (2));
+.IP \[bu]
+allow the
+.B RLIMIT_NOFILE
+resource limit on the number of "in-flight" file descriptors
+to be bypassed when passing file descriptors to another process
+via a UNIX domain socket (see
+.BR unix (7));
+.IP \[bu]
+override the
+.I /proc/sys/fs/pipe\-size\-max
+limit when setting the capacity of a pipe using the
+.B F_SETPIPE_SZ
+.BR fcntl (2)
+command;
+.IP \[bu]
+use
+.B F_SETPIPE_SZ
+to increase the capacity of a pipe above the limit specified by
+.IR /proc/sys/fs/pipe\-max\-size ;
+.IP \[bu]
+override
+.IR /proc/sys/fs/mqueue/queues_max ,
+.IR /proc/sys/fs/mqueue/msg_max ,
+and
+.I /proc/sys/fs/mqueue/msgsize_max
+limits when creating POSIX message queues (see
+.BR mq_overview (7));
+.IP \[bu]
+employ the
+.BR prctl (2)
+.B PR_SET_MM
+operation;
+.IP \[bu]
+set
+.IR /proc/ pid /oom_score_adj
+to a value lower than the value last set by a process with
+.BR CAP_SYS_RESOURCE .
+.RE
+.PD
+.TP
+.B CAP_SYS_TIME
+Set system clock
+.RB ( settimeofday (2),
+.BR stime (2),
+.BR adjtimex (2));
+set real-time (hardware) clock.
+.TP
+.B CAP_SYS_TTY_CONFIG
+Use
+.BR vhangup (2);
+employ various privileged
+.BR ioctl (2)
+operations on virtual terminals.
+.TP
+.BR CAP_SYSLOG " (since Linux 2.6.37)"
+.RS
+.PD 0
+.IP \[bu] 3
+Perform privileged
+.BR syslog (2)
+operations.
+See
+.BR syslog (2)
+for information on which operations require privilege.
+.IP \[bu]
+View kernel addresses exposed via
+.I /proc
+and other interfaces when
+.I /proc/sys/kernel/kptr_restrict
+has the value 1.
+(See the discussion of the
+.I kptr_restrict
+in
+.BR proc (5).)
+.PD
+.RE
+.TP
+.BR CAP_WAKE_ALARM " (since Linux 3.0)"
+Trigger something that will wake up the system (set
+.B CLOCK_REALTIME_ALARM
+and
+.B CLOCK_BOOTTIME_ALARM
+timers).
+.\"
+.SS Past and current implementation
+A full implementation of capabilities requires that:
+.IP \[bu] 3
+For all privileged operations,
+the kernel must check whether the thread has the required
+capability in its effective set.
+.IP \[bu]
+The kernel must provide system calls allowing a thread's capability sets to
+be changed and retrieved.
+.IP \[bu]
+The filesystem must support attaching capabilities to an executable file,
+so that a process gains those capabilities when the file is executed.
+.P
+Before Linux 2.6.24, only the first two of these requirements are met;
+since Linux 2.6.24, all three requirements are met.
+.\"
+.SS Notes to kernel developers
+When adding a new kernel feature that should be governed by a capability,
+consider the following points.
+.IP \[bu] 3
+The goal of capabilities is divide the power of superuser into pieces,
+such that if a program that has one or more capabilities is compromised,
+its power to do damage to the system would be less than the same program
+running with root privilege.
+.IP \[bu]
+You have the choice of either creating a new capability for your new feature,
+or associating the feature with one of the existing capabilities.
+In order to keep the set of capabilities to a manageable size,
+the latter option is preferable,
+unless there are compelling reasons to take the former option.
+(There is also a technical limit:
+the size of capability sets is currently limited to 64 bits.)
+.IP \[bu]
+To determine which existing capability might best be associated
+with your new feature, review the list of capabilities above in order
+to find a "silo" into which your new feature best fits.
+One approach to take is to determine if there are other features
+requiring capabilities that will always be used along with the new feature.
+If the new feature is useless without these other features,
+you should use the same capability as the other features.
+.IP \[bu]
+.I Don't
+choose
+.B CAP_SYS_ADMIN
+if you can possibly avoid it!
+A vast proportion of existing capability checks are associated
+with this capability (see the partial list above).
+It can plausibly be called "the new root",
+since on the one hand, it confers a wide range of powers,
+and on the other hand,
+its broad scope means that this is the capability
+that is required by many privileged programs.
+Don't make the problem worse.
+The only new features that should be associated with
+.B CAP_SYS_ADMIN
+are ones that
+.I closely
+match existing uses in that silo.
+.IP \[bu]
+If you have determined that it really is necessary to create
+a new capability for your feature,
+don't make or name it as a "single-use" capability.
+Thus, for example, the addition of the highly specific
+.B CAP_SYS_PACCT
+was probably a mistake.
+Instead, try to identify and name your new capability as a broader
+silo into which other related future use cases might fit.
+.\"
+.SS Thread capability sets
+Each thread has the following capability sets containing zero or more
+of the above capabilities:
+.TP
+.I Permitted
+This is a limiting superset for the effective
+capabilities that the thread may assume.
+It is also a limiting superset for the capabilities that
+may be added to the inheritable set by a thread that does not have the
+.B CAP_SETPCAP
+capability in its effective set.
+.IP
+If a thread drops a capability from its permitted set,
+it can never reacquire that capability (unless it
+.BR execve (2)s
+either a set-user-ID-root program, or
+a program whose associated file capabilities grant that capability).
+.TP
+.I Inheritable
+This is a set of capabilities preserved across an
+.BR execve (2).
+Inheritable capabilities remain inheritable when executing any program,
+and inheritable capabilities are added to the permitted set when executing
+a program that has the corresponding bits set in the file inheritable set.
+.IP
+Because inheritable capabilities are not generally preserved across
+.BR execve (2)
+when running as a non-root user, applications that wish to run helper
+programs with elevated capabilities should consider using
+ambient capabilities, described below.
+.TP
+.I Effective
+This is the set of capabilities used by the kernel to
+perform permission checks for the thread.
+.TP
+.IR Bounding " (per-thread since Linux 2.6.25)"
+The capability bounding set is a mechanism that can be used
+to limit the capabilities that are gained during
+.BR execve (2).
+.IP
+Since Linux 2.6.25, this is a per-thread capability set.
+In older kernels, the capability bounding set was a system wide attribute
+shared by all threads on the system.
+.IP
+For more details, see
+.I Capability bounding set
+below.
+.TP
+.IR Ambient " (since Linux 4.3)"
+.\" commit 58319057b7847667f0c9585b9de0e8932b0fdb08
+This is a set of capabilities that are preserved across an
+.BR execve (2)
+of a program that is not privileged.
+The ambient capability set obeys the invariant that no capability
+can ever be ambient if it is not both permitted and inheritable.
+.IP
+The ambient capability set can be directly modified using
+.BR prctl (2).
+Ambient capabilities are automatically lowered if either of
+the corresponding permitted or inheritable capabilities is lowered.
+.IP
+Executing a program that changes UID or GID due to the
+set-user-ID or set-group-ID bits or executing a program that has
+any file capabilities set will clear the ambient set.
+Ambient capabilities are added to the permitted set and
+assigned to the effective set when
+.BR execve (2)
+is called.
+If ambient capabilities cause a process's permitted and effective
+capabilities to increase during an
+.BR execve (2),
+this does not trigger the secure-execution mode described in
+.BR ld.so (8).
+.P
+A child created via
+.BR fork (2)
+inherits copies of its parent's capability sets.
+For details on how
+.BR execve (2)
+affects capabilities, see
+.I Transformation of capabilities during execve()
+below.
+.P
+Using
+.BR capset (2),
+a thread may manipulate its own capability sets; see
+.I Programmatically adjusting capability sets
+below.
+.P
+Since Linux 3.2, the file
+.I /proc/sys/kernel/cap_last_cap
+.\" commit 73efc0394e148d0e15583e13712637831f926720
+exposes the numerical value of the highest capability
+supported by the running kernel;
+this can be used to determine the highest bit
+that may be set in a capability set.
+.\"
+.SS File capabilities
+Since Linux 2.6.24, the kernel supports
+associating capability sets with an executable file using
+.BR setcap (8).
+The file capability sets are stored in an extended attribute (see
+.BR setxattr (2)
+and
+.BR xattr (7))
+named
+.IR "security.capability" .
+Writing to this extended attribute requires the
+.B CAP_SETFCAP
+capability.
+The file capability sets,
+in conjunction with the capability sets of the thread,
+determine the capabilities of a thread after an
+.BR execve (2).
+.P
+The three file capability sets are:
+.TP
+.IR Permitted " (formerly known as " forced ):
+These capabilities are automatically permitted to the thread,
+regardless of the thread's inheritable capabilities.
+.TP
+.IR Inheritable " (formerly known as " allowed ):
+This set is ANDed with the thread's inheritable set to determine which
+inheritable capabilities are enabled in the permitted set of
+the thread after the
+.BR execve (2).
+.TP
+.IR Effective :
+This is not a set, but rather just a single bit.
+If this bit is set, then during an
+.BR execve (2)
+all of the new permitted capabilities for the thread are
+also raised in the effective set.
+If this bit is not set, then after an
+.BR execve (2),
+none of the new permitted capabilities is in the new effective set.
+.IP
+Enabling the file effective capability bit implies
+that any file permitted or inheritable capability that causes a
+thread to acquire the corresponding permitted capability during an
+.BR execve (2)
+(see
+.I Transformation of capabilities during execve()
+below) will also acquire that
+capability in its effective set.
+Therefore, when assigning capabilities to a file
+.RB ( setcap (8),
+.BR cap_set_file (3),
+.BR cap_set_fd (3)),
+if we specify the effective flag as being enabled for any capability,
+then the effective flag must also be specified as enabled
+for all other capabilities for which the corresponding permitted or
+inheritable flag is enabled.
+.\"
+.SS File capability extended attribute versioning
+To allow extensibility,
+the kernel supports a scheme to encode a version number inside the
+.I security.capability
+extended attribute that is used to implement file capabilities.
+These version numbers are internal to the implementation,
+and not directly visible to user-space applications.
+To date, the following versions are supported:
+.TP
+.B VFS_CAP_REVISION_1
+This was the original file capability implementation,
+which supported 32-bit masks for file capabilities.
+.TP
+.BR VFS_CAP_REVISION_2 " (since Linux 2.6.25)"
+.\" commit e338d263a76af78fe8f38a72131188b58fceb591
+This version allows for file capability masks that are 64 bits in size,
+and was necessary as the number of supported capabilities grew beyond 32.
+The kernel transparently continues to support the execution of files
+that have 32-bit version 1 capability masks,
+but when adding capabilities to files that did not previously
+have capabilities, or modifying the capabilities of existing files,
+it automatically uses the version 2 scheme
+(or possibly the version 3 scheme, as described below).
+.TP
+.BR VFS_CAP_REVISION_3 " (since Linux 4.14)"
+.\" commit 8db6c34f1dbc8e06aa016a9b829b06902c3e1340
+Version 3 file capabilities are provided
+to support namespaced file capabilities (described below).
+.IP
+As with version 2 file capabilities,
+version 3 capability masks are 64 bits in size.
+But in addition, the root user ID of namespace is encoded in the
+.I security.capability
+extended attribute.
+(A namespace's root user ID is the value that user ID 0
+inside that namespace maps to in the initial user namespace.)
+.IP
+Version 3 file capabilities are designed to coexist
+with version 2 capabilities;
+that is, on a modern Linux system,
+there may be some files with version 2 capabilities
+while others have version 3 capabilities.
+.P
+Before Linux 4.14,
+the only kind of file capability extended attribute
+that could be attached to a file was a
+.B VFS_CAP_REVISION_2
+attribute.
+Since Linux 4.14,
+the version of the
+.I security.capability
+extended attribute that is attached to a file
+depends on the circumstances in which the attribute was created.
+.P
+Starting with Linux 4.14, a
+.I security.capability
+extended attribute is automatically created as (or converted to)
+a version 3
+.RB ( VFS_CAP_REVISION_3 )
+attribute if both of the following are true:
+.IP \[bu] 3
+The thread writing the attribute resides in a noninitial user namespace.
+(More precisely: the thread resides in a user namespace other
+than the one from which the underlying filesystem was mounted.)
+.IP \[bu]
+The thread has the
+.B CAP_SETFCAP
+capability over the file inode,
+meaning that (a) the thread has the
+.B CAP_SETFCAP
+capability in its own user namespace;
+and (b) the UID and GID of the file inode have mappings in
+the writer's user namespace.
+.P
+When a
+.B VFS_CAP_REVISION_3
+.I security.capability
+extended attribute is created, the root user ID of the creating thread's
+user namespace is saved in the extended attribute.
+.P
+By contrast, creating or modifying a
+.I security.capability
+extended attribute from a privileged
+.RB ( CAP_SETFCAP )
+thread that resides in the
+namespace where the underlying filesystem was mounted
+(this normally means the initial user namespace)
+automatically results in the creation of a version 2
+.RB ( VFS_CAP_REVISION_2 )
+attribute.
+.P
+Note that the creation of a version 3
+.I security.capability
+extended attribute is automatic.
+That is to say, when a user-space application writes
+.RB ( setxattr (2))
+a
+.I security.capability
+attribute in the version 2 format,
+the kernel will automatically create a version 3 attribute
+if the attribute is created in the circumstances described above.
+Correspondingly, when a version 3
+.I security.capability
+attribute is retrieved
+.RB ( getxattr (2))
+by a process that resides inside a user namespace that was created by the
+root user ID (or a descendant of that user namespace),
+the returned attribute is (automatically)
+simplified to appear as a version 2 attribute
+(i.e., the returned value is the size of a version 2 attribute and does
+not include the root user ID).
+These automatic translations mean that no changes are required to
+user-space tools (e.g.,
+.BR setcap (1)
+and
+.BR getcap (1))
+in order for those tools to be used to create and retrieve version 3
+.I security.capability
+attributes.
+.P
+Note that a file can have either a version 2 or a version 3
+.I security.capability
+extended attribute associated with it, but not both:
+creation or modification of the
+.I security.capability
+extended attribute will automatically modify the version
+according to the circumstances in which the extended attribute is
+created or modified.
+.\"
+.SS Transformation of capabilities during execve()
+During an
+.BR execve (2),
+the kernel calculates the new capabilities of
+the process using the following algorithm:
+.P
+.in +4n
+.EX
+P'(ambient)     = (file is privileged) ? 0 : P(ambient)
+\&
+P'(permitted)   = (P(inheritable) & F(inheritable)) |
+                  (F(permitted) & P(bounding)) | P'(ambient)
+\&
+P'(effective)   = F(effective) ? P'(permitted) : P'(ambient)
+\&
+P'(inheritable) = P(inheritable)    [i.e., unchanged]
+\&
+P'(bounding)    = P(bounding)       [i.e., unchanged]
+.EE
+.in
+.P
+where:
+.RS 4
+.TP
+P()
+denotes the value of a thread capability set before the
+.BR execve (2)
+.TP
+P'()
+denotes the value of a thread capability set after the
+.BR execve (2)
+.TP
+F()
+denotes a file capability set
+.RE
+.P
+Note the following details relating to the above capability
+transformation rules:
+.IP \[bu] 3
+The ambient capability set is present only since Linux 4.3.
+When determining the transformation of the ambient set during
+.BR execve (2),
+a privileged file is one that has capabilities or
+has the set-user-ID or set-group-ID bit set.
+.IP \[bu]
+Prior to Linux 2.6.25,
+the bounding set was a system-wide attribute shared by all threads.
+That system-wide value was employed to calculate the new permitted set during
+.BR execve (2)
+in the same manner as shown above for
+.IR P(bounding) .
+.P
+.IR Note :
+during the capability transitions described above,
+file capabilities may be ignored (treated as empty) for the same reasons
+that the set-user-ID and set-group-ID bits are ignored; see
+.BR execve (2).
+File capabilities are similarly ignored if the kernel was booted with the
+.I no_file_caps
+option.
+.P
+.IR Note :
+according to the rules above,
+if a process with nonzero user IDs performs an
+.BR execve (2)
+then any capabilities that are present in
+its permitted and effective sets will be cleared.
+For the treatment of capabilities when a process with a
+user ID of zero performs an
+.BR execve (2),
+see
+.I Capabilities and execution of programs by root
+below.
+.\"
+.SS Safety checking for capability-dumb binaries
+A capability-dumb binary is an application that has been
+marked to have file capabilities, but has not been converted to use the
+.BR libcap (3)
+API to manipulate its capabilities.
+(In other words, this is a traditional set-user-ID-root program
+that has been switched to use file capabilities,
+but whose code has not been modified to understand capabilities.)
+For such applications,
+the effective capability bit is set on the file,
+so that the file permitted capabilities are automatically
+enabled in the process effective set when executing the file.
+The kernel recognizes a file which has the effective capability bit set
+as capability-dumb for the purpose of the check described here.
+.P
+When executing a capability-dumb binary,
+the kernel checks if the process obtained all permitted capabilities
+that were specified in the file permitted set,
+after the capability transformations described above have been performed.
+(The typical reason why this might
+.I not
+occur is that the capability bounding set masked out some
+of the capabilities in the file permitted set.)
+If the process did not obtain the full set of
+file permitted capabilities, then
+.BR execve (2)
+fails with the error
+.BR EPERM .
+This prevents possible security risks that could arise when
+a capability-dumb application is executed with less privilege than it needs.
+Note that, by definition,
+the application could not itself recognize this problem,
+since it does not employ the
+.BR libcap (3)
+API.
+.\"
+.SS Capabilities and execution of programs by root
+.\" See cap_bprm_set_creds(), bprm_caps_from_vfs_cap() and
+.\" handle_privileged_root() in security/commoncap.c (Linux 5.0 source)
+In order to mirror traditional UNIX semantics,
+the kernel performs special treatment of file capabilities when
+a process with UID 0 (root) executes a program and
+when a set-user-ID-root program is executed.
+.P
+After having performed any changes to the process effective ID that
+were triggered by the set-user-ID mode bit of the binary\[em]e.g.,
+switching the effective user ID to 0 (root) because
+a set-user-ID-root program was executed\[em]the
+kernel calculates the file capability sets as follows:
+.IP (1) 5
+If the real or effective user ID of the process is 0 (root),
+then the file inheritable and permitted sets are ignored;
+instead they are notionally considered to be all ones
+(i.e., all capabilities enabled).
+(There is one exception to this behavior, described in
+.I Set-user-ID-root programs that have file capabilities
+below.)
+.IP (2)
+If the effective user ID of the process is 0 (root) or
+the file effective bit is in fact enabled,
+then the file effective bit is notionally defined to be one (enabled).
+.P
+These notional values for the file's capability sets are then used
+as described above to calculate the transformation of the process's
+capabilities during
+.BR execve (2).
+.P
+Thus, when a process with nonzero UIDs
+.BR execve (2)s
+a set-user-ID-root program that does not have capabilities attached,
+or when a process whose real and effective UIDs are zero
+.BR execve (2)s
+a program, the calculation of the process's new
+permitted capabilities simplifies to:
+.P
+.in +4n
+.EX
+P'(permitted)   = P(inheritable) | P(bounding)
+\&
+P'(effective)   = P'(permitted)
+.EE
+.in
+.P
+Consequently, the process gains all capabilities in its permitted and
+effective capability sets,
+except those masked out by the capability bounding set.
+(In the calculation of P'(permitted),
+the P'(ambient) term can be simplified away because it is by
+definition a proper subset of P(inheritable).)
+.P
+The special treatments of user ID 0 (root) described in this subsection
+can be disabled using the securebits mechanism described below.
+.\"
+.\"
+.SS Set-user-ID-root programs that have file capabilities
+There is one exception to the behavior described in
+.I Capabilities and execution of programs by root
+above.
+If (a) the binary that is being executed has capabilities attached and
+(b) the real user ID of the process is
+.I not
+0 (root) and
+(c) the effective user ID of the process
+.I is
+0 (root), then the file capability bits are honored
+(i.e., they are not notionally considered to be all ones).
+The usual way in which this situation can arise is when executing
+a set-UID-root program that also has file capabilities.
+When such a program is executed,
+the process gains just the capabilities granted by the program
+(i.e., not all capabilities,
+as would occur when executing a set-user-ID-root program
+that does not have any associated file capabilities).
+.P
+Note that one can assign empty capability sets to a program file,
+and thus it is possible to create a set-user-ID-root program that
+changes the effective and saved set-user-ID of the process
+that executes the program to 0,
+but confers no capabilities to that process.
+.\"
+.SS Capability bounding set
+The capability bounding set is a security mechanism that can be used
+to limit the capabilities that can be gained during an
+.BR execve (2).
+The bounding set is used in the following ways:
+.IP \[bu] 3
+During an
+.BR execve (2),
+the capability bounding set is ANDed with the file permitted
+capability set, and the result of this operation is assigned to the
+thread's permitted capability set.
+The capability bounding set thus places a limit on the permitted
+capabilities that may be granted by an executable file.
+.IP \[bu]
+(Since Linux 2.6.25)
+The capability bounding set acts as a limiting superset for
+the capabilities that a thread can add to its inheritable set using
+.BR capset (2).
+This means that if a capability is not in the bounding set,
+then a thread can't add this capability to its
+inheritable set, even if it was in its permitted capabilities,
+and thereby cannot have this capability preserved in its
+permitted set when it
+.BR execve (2)s
+a file that has the capability in its inheritable set.
+.P
+Note that the bounding set masks the file permitted capabilities,
+but not the inheritable capabilities.
+If a thread maintains a capability in its inheritable set
+that is not in its bounding set,
+then it can still gain that capability in its permitted set
+by executing a file that has the capability in its inheritable set.
+.P
+Depending on the kernel version, the capability bounding set is either
+a system-wide attribute, or a per-process attribute.
+.P
+.B "Capability bounding set from Linux 2.6.25 onward"
+.P
+From Linux 2.6.25, the
+.I "capability bounding set"
+is a per-thread attribute.
+(The system-wide capability bounding set described below no longer exists.)
+.P
+The bounding set is inherited at
+.BR fork (2)
+from the thread's parent, and is preserved across an
+.BR execve (2).
+.P
+A thread may remove capabilities from its capability bounding set using the
+.BR prctl (2)
+.B PR_CAPBSET_DROP
+operation, provided it has the
+.B CAP_SETPCAP
+capability.
+Once a capability has been dropped from the bounding set,
+it cannot be restored to that set.
+A thread can determine if a capability is in its bounding set using the
+.BR prctl (2)
+.B PR_CAPBSET_READ
+operation.
+.P
+Removing capabilities from the bounding set is supported only if file
+capabilities are compiled into the kernel.
+Before Linux 2.6.33,
+file capabilities were an optional feature configurable via the
+.B CONFIG_SECURITY_FILE_CAPABILITIES
+option.
+Since Linux 2.6.33,
+.\" commit b3a222e52e4d4be77cc4520a57af1a4a0d8222d1
+the configuration option has been removed
+and file capabilities are always part of the kernel.
+When file capabilities are compiled into the kernel, the
+.B init
+process (the ancestor of all processes) begins with a full bounding set.
+If file capabilities are not compiled into the kernel, then
+.B init
+begins with a full bounding set minus
+.BR CAP_SETPCAP ,
+because this capability has a different meaning when there are
+no file capabilities.
+.P
+Removing a capability from the bounding set does not remove it
+from the thread's inheritable set.
+However it does prevent the capability from being added
+back into the thread's inheritable set in the future.
+.P
+.B "Capability bounding set prior to Linux 2.6.25"
+.P
+Before Linux 2.6.25, the capability bounding set is a system-wide
+attribute that affects all threads on the system.
+The bounding set is accessible via the file
+.IR /proc/sys/kernel/cap\-bound .
+(Confusingly, this bit mask parameter is expressed as a
+signed decimal number in
+.IR /proc/sys/kernel/cap\-bound .)
+.P
+Only the
+.B init
+process may set capabilities in the capability bounding set;
+other than that, the superuser (more precisely: a process with the
+.B CAP_SYS_MODULE
+capability) may only clear capabilities from this set.
+.P
+On a standard system the capability bounding set always masks out the
+.B CAP_SETPCAP
+capability.
+To remove this restriction (dangerous!), modify the definition of
+.B CAP_INIT_EFF_SET
+in
+.I include/linux/capability.h
+and rebuild the kernel.
+.P
+The system-wide capability bounding set feature was added
+to Linux 2.2.11.
+.\"
+.\"
+.\"
+.SS Effect of user ID changes on capabilities
+To preserve the traditional semantics for transitions between
+0 and nonzero user IDs,
+the kernel makes the following changes to a thread's capability
+sets on changes to the thread's real, effective, saved set,
+and filesystem user IDs (using
+.BR setuid (2),
+.BR setresuid (2),
+or similar):
+.IP \[bu] 3
+If one or more of the real, effective, or saved set user IDs
+was previously 0, and as a result of the UID changes all of these IDs
+have a nonzero value,
+then all capabilities are cleared from the permitted, effective, and ambient
+capability sets.
+.IP \[bu]
+If the effective user ID is changed from 0 to nonzero,
+then all capabilities are cleared from the effective set.
+.IP \[bu]
+If the effective user ID is changed from nonzero to 0,
+then the permitted set is copied to the effective set.
+.IP \[bu]
+If the filesystem user ID is changed from 0 to nonzero (see
+.BR setfsuid (2)),
+then the following capabilities are cleared from the effective set:
+.BR CAP_CHOWN ,
+.BR CAP_DAC_OVERRIDE ,
+.BR CAP_DAC_READ_SEARCH ,
+.BR CAP_FOWNER ,
+.BR CAP_FSETID ,
+.B CAP_LINUX_IMMUTABLE
+(since Linux 2.6.30),
+.BR CAP_MAC_OVERRIDE ,
+and
+.B CAP_MKNOD
+(since Linux 2.6.30).
+If the filesystem UID is changed from nonzero to 0,
+then any of these capabilities that are enabled in the permitted set
+are enabled in the effective set.
+.P
+If a thread that has a 0 value for one or more of its user IDs wants
+to prevent its permitted capability set being cleared when it resets
+all of its user IDs to nonzero values, it can do so using the
+.B SECBIT_KEEP_CAPS
+securebits flag described below.
+.\"
+.SS Programmatically adjusting capability sets
+A thread can retrieve and change its permitted, effective, and inheritable
+capability sets using the
+.BR capget (2)
+and
+.BR capset (2)
+system calls.
+However, the use of
+.BR cap_get_proc (3)
+and
+.BR cap_set_proc (3),
+both provided in the
+.I libcap
+package,
+is preferred for this purpose.
+The following rules govern changes to the thread capability sets:
+.IP \[bu] 3
+If the caller does not have the
+.B CAP_SETPCAP
+capability,
+the new inheritable set must be a subset of the combination
+of the existing inheritable and permitted sets.
+.IP \[bu]
+(Since Linux 2.6.25)
+The new inheritable set must be a subset of the combination of the
+existing inheritable set and the capability bounding set.
+.IP \[bu]
+The new permitted set must be a subset of the existing permitted set
+(i.e., it is not possible to acquire permitted capabilities
+that the thread does not currently have).
+.IP \[bu]
+The new effective set must be a subset of the new permitted set.
+.SS The securebits flags: establishing a capabilities-only environment
+.\" For some background:
+.\"       see http://lwn.net/Articles/280279/ and
+.\"       http://article.gmane.org/gmane.linux.kernel.lsm/5476/
+Starting with Linux 2.6.26,
+and with a kernel in which file capabilities are enabled,
+Linux implements a set of per-thread
+.I securebits
+flags that can be used to disable special handling of capabilities for UID 0
+.RI ( root ).
+These flags are as follows:
+.TP
+.B SECBIT_KEEP_CAPS
+Setting this flag allows a thread that has one or more 0 UIDs to retain
+capabilities in its permitted set
+when it switches all of its UIDs to nonzero values.
+If this flag is not set,
+then such a UID switch causes the thread to lose all permitted capabilities.
+This flag is always cleared on an
+.BR execve (2).
+.IP
+Note that even with the
+.B SECBIT_KEEP_CAPS
+flag set, the effective capabilities of a thread are cleared when it
+switches its effective UID to a nonzero value.
+However,
+if the thread has set this flag and its effective UID is already nonzero,
+and the thread subsequently switches all other UIDs to nonzero values,
+then the effective capabilities will not be cleared.
+.IP
+The setting of the
+.B SECBIT_KEEP_CAPS
+flag is ignored if the
+.B SECBIT_NO_SETUID_FIXUP
+flag is set.
+(The latter flag provides a superset of the effect of the former flag.)
+.IP
+This flag provides the same functionality as the older
+.BR prctl (2)
+.B PR_SET_KEEPCAPS
+operation.
+.TP
+.B SECBIT_NO_SETUID_FIXUP
+Setting this flag stops the kernel from adjusting the process's
+permitted, effective, and ambient capability sets when
+the thread's effective and filesystem UIDs are switched between
+zero and nonzero values.
+See
+.I Effect of user ID changes on capabilities
+above.
+.TP
+.B SECBIT_NOROOT
+If this bit is set, then the kernel does not grant capabilities
+when a set-user-ID-root program is executed, or when a process with
+an effective or real UID of 0 calls
+.BR execve (2).
+(See
+.I Capabilities and execution of programs by root
+above.)
+.TP
+.B SECBIT_NO_CAP_AMBIENT_RAISE
+Setting this flag disallows raising ambient capabilities via the
+.BR prctl (2)
+.B PR_CAP_AMBIENT_RAISE
+operation.
+.P
+Each of the above "base" flags has a companion "locked" flag.
+Setting any of the "locked" flags is irreversible,
+and has the effect of preventing further changes to the
+corresponding "base" flag.
+The locked flags are:
+.BR SECBIT_KEEP_CAPS_LOCKED ,
+.BR SECBIT_NO_SETUID_FIXUP_LOCKED ,
+.BR SECBIT_NOROOT_LOCKED ,
+and
+.BR SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED .
+.P
+The
+.I securebits
+flags can be modified and retrieved using the
+.BR prctl (2)
+.B PR_SET_SECUREBITS
+and
+.B PR_GET_SECUREBITS
+operations.
+The
+.B CAP_SETPCAP
+capability is required to modify the flags.
+Note that the
+.B SECBIT_*
+constants are available only after including the
+.I <linux/securebits.h>
+header file.
+.P
+The
+.I securebits
+flags are inherited by child processes.
+During an
+.BR execve (2),
+all of the flags are preserved, except
+.B SECBIT_KEEP_CAPS
+which is always cleared.
+.P
+An application can use the following call to lock itself,
+and all of its descendants,
+into an environment where the only way of gaining capabilities
+is by executing a program with associated file capabilities:
+.P
+.in +4n
+.EX
+prctl(PR_SET_SECUREBITS,
+        /* SECBIT_KEEP_CAPS off */
+        SECBIT_KEEP_CAPS_LOCKED |
+        SECBIT_NO_SETUID_FIXUP |
+        SECBIT_NO_SETUID_FIXUP_LOCKED |
+        SECBIT_NOROOT |
+        SECBIT_NOROOT_LOCKED);
+        /* Setting/locking SECBIT_NO_CAP_AMBIENT_RAISE
+           is not required */
+.EE
+.in
+.\"
+.\"
+.SS Per-user-namespace \[dq]set-user-ID-root\[dq] programs
+A set-user-ID program whose UID matches the UID that
+created a user namespace will confer capabilities
+in the process's permitted and effective sets
+when executed by any process inside that namespace
+or any descendant user namespace.
+.P
+The rules about the transformation of the process's capabilities during the
+.BR execve (2)
+are exactly as described in
+.I Transformation of capabilities during execve()
+and
+.I Capabilities and execution of programs by root
+above,
+with the difference that, in the latter subsection, "root"
+is the UID of the creator of the user namespace.
+.\"
+.\"
+.SS Namespaced file capabilities
+.\" commit 8db6c34f1dbc8e06aa016a9b829b06902c3e1340
+Traditional (i.e., version 2) file capabilities associate
+only a set of capability masks with a binary executable file.
+When a process executes a binary with such capabilities,
+it gains the associated capabilities (within its user namespace)
+as per the rules described in
+.I Transformation of capabilities during execve()
+above.
+.P
+Because version 2 file capabilities confer capabilities to
+the executing process regardless of which user namespace it resides in,
+only privileged processes are permitted to associate capabilities with a file.
+Here, "privileged" means a process that has the
+.B CAP_SETFCAP
+capability in the user namespace where the filesystem was mounted
+(normally the initial user namespace).
+This limitation renders file capabilities useless for certain use cases.
+For example, in user-namespaced containers,
+it can be desirable to be able to create a binary that
+confers capabilities only to processes executed inside that container,
+but not to processes that are executed outside the container.
+.P
+Linux 4.14 added so-called namespaced file capabilities
+to support such use cases.
+Namespaced file capabilities are recorded as version 3 (i.e.,
+.BR VFS_CAP_REVISION_3 )
+.I security.capability
+extended attributes.
+Such an attribute is automatically created in the circumstances described
+in
+.I File capability extended attribute versioning
+above.
+When a version 3
+.I security.capability
+extended attribute is created,
+the kernel records not just the capability masks in the extended attribute,
+but also the namespace root user ID.
+.P
+As with a binary that has
+.B VFS_CAP_REVISION_2
+file capabilities, a binary with
+.B VFS_CAP_REVISION_3
+file capabilities confers capabilities to a process during
+.BR execve ().
+However, capabilities are conferred only if the binary is executed by
+a process that resides in a user namespace whose
+UID 0 maps to the root user ID that is saved in the extended attribute,
+or when executed by a process that resides in a descendant of such a namespace.
+.\"
+.\"
+.SS Interaction with user namespaces
+For further information on the interaction of
+capabilities and user namespaces, see
+.BR user_namespaces (7).
+.SH STANDARDS
+No standards govern capabilities, but the Linux capability implementation
+is based on the withdrawn
+.UR https://archive.org\:/details\:/posix_1003.1e\-990310
+POSIX.1e draft standard
+.UE .
+.SH NOTES
+When attempting to
+.BR strace (1)
+binaries that have capabilities (or set-user-ID-root binaries),
+you may find the
+.I \-u <username>
+option useful.
+Something like:
+.P
+.in +4n
+.EX
+$ \fBsudo strace \-o trace.log \-u ceci ./myprivprog\fP
+.EE
+.in
+.P
+From Linux 2.5.27 to Linux 2.6.26,
+.\" commit 5915eb53861c5776cfec33ca4fcc1fd20d66dd27 removed
+.\" CONFIG_SECURITY_CAPABILITIES
+capabilities were an optional kernel component,
+and could be enabled/disabled via the
+.B CONFIG_SECURITY_CAPABILITIES
+kernel configuration option.
+.P
+The
+.IR /proc/ pid /task/TID/status
+file can be used to view the capability sets of a thread.
+The
+.IR /proc/ pid /status
+file shows the capability sets of a process's main thread.
+Before Linux 3.8, nonexistent capabilities were shown as being
+enabled (1) in these sets.
+Since Linux 3.8,
+.\" 7b9a7ec565505699f503b4fcf61500dceb36e744
+all nonexistent capabilities (above
+.BR CAP_LAST_CAP )
+are shown as disabled (0).
+.P
+The
+.I libcap
+package provides a suite of routines for setting and
+getting capabilities that is more comfortable and less likely
+to change than the interface provided by
+.BR capset (2)
+and
+.BR capget (2).
+This package also provides the
+.BR setcap (8)
+and
+.BR getcap (8)
+programs.
+It can be found at
+.br
+.UR https://git.kernel.org\:/pub\:/scm\:/libs\:/libcap\:/libcap.git\:/refs/
+.UE .
+.P
+Before Linux 2.6.24, and from Linux 2.6.24 to Linux 2.6.32 if
+file capabilities are not enabled, a thread with the
+.B CAP_SETPCAP
+capability can manipulate the capabilities of threads other than itself.
+However, this is only theoretically possible,
+since no thread ever has
+.B CAP_SETPCAP
+in either of these cases:
+.IP \[bu] 3
+In the pre-2.6.25 implementation the system-wide capability bounding set,
+.IR /proc/sys/kernel/cap\-bound ,
+always masks out the
+.B CAP_SETPCAP
+capability, and this can not be changed
+without modifying the kernel source and rebuilding the kernel.
+.IP \[bu]
+If file capabilities are disabled (i.e., the kernel
+.B CONFIG_SECURITY_FILE_CAPABILITIES
+option is disabled), then
+.B init
+starts out with the
+.B CAP_SETPCAP
+capability removed from its per-process bounding
+set, and that bounding set is inherited by all other processes
+created on the system.
+.SH SEE ALSO
+.BR capsh (1),
+.BR setpriv (1),
+.BR prctl (2),
+.BR setfsuid (2),
+.BR cap_clear (3),
+.BR cap_copy_ext (3),
+.BR cap_from_text (3),
+.BR cap_get_file (3),
+.BR cap_get_proc (3),
+.BR cap_init (3),
+.BR capgetp (3),
+.BR capsetp (3),
+.BR libcap (3),
+.BR proc (5),
+.BR credentials (7),
+.BR pthreads (7),
+.BR user_namespaces (7),
+.BR captest (8), \" from libcap-ng
+.BR filecap (8), \" from libcap-ng
+.BR getcap (8),
+.BR getpcaps (8),
+.BR netcap (8), \" from libcap-ng
+.BR pscap (8), \" from libcap-ng
+.BR setcap (8)
+.P
+.I include/linux/capability.h
+in the Linux kernel source tree
diff --git a/man/man7/cgroup_namespaces.7 b/man/man7/cgroup_namespaces.7
new file mode 100644
index 000000000..10f16c666
--- /dev/null
+++ b/man/man7/cgroup_namespaces.7
@@ -0,0 +1,248 @@
+.\" Copyright (c) 2016 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH cgroup_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cgroup_namespaces \- overview of Linux cgroup namespaces
+.SH DESCRIPTION
+For an overview of namespaces, see
+.BR namespaces (7).
+.P
+Cgroup namespaces virtualize the view of a process's cgroups (see
+.BR cgroups (7))
+as seen via
+.IR /proc/ pid /cgroup
+and
+.IR /proc/ pid /mountinfo .
+.P
+Each cgroup namespace has its own set of cgroup root directories.
+These root directories are the base points for the relative
+locations displayed in the corresponding records in the
+.IR /proc/ pid /cgroup
+file.
+When a process creates a new cgroup namespace using
+.BR clone (2)
+or
+.BR unshare (2)
+with the
+.B CLONE_NEWCGROUP
+flag, its current
+cgroups directories become the cgroup root directories
+of the new namespace.
+(This applies both for the cgroups version 1 hierarchies
+and the cgroups version 2 unified hierarchy.)
+.P
+When reading the cgroup memberships of a "target" process from
+.IR /proc/ pid /cgroup ,
+the pathname shown in the third field of each record will be
+relative to the reading process's root directory
+for the corresponding cgroup hierarchy.
+If the cgroup directory of the target process lies outside
+the root directory of the reading process's cgroup namespace,
+then the pathname will show
+.I ../
+entries for each ancestor level in the cgroup hierarchy.
+.P
+The following shell session demonstrates the effect of creating
+a new cgroup namespace.
+.P
+First, (as superuser) in a shell in the initial cgroup namespace,
+we create a child cgroup in the
+.I freezer
+hierarchy, and place a process in that cgroup that we will
+use as part of the demonstration below:
+.P
+.in +4n
+.EX
+# \fBmkdir \-p /sys/fs/cgroup/freezer/sub2\fP
+# \fBsleep 10000 &\fP     # Create a process that lives for a while
+[1] 20124
+# \fBecho 20124 > /sys/fs/cgroup/freezer/sub2/cgroup.procs\fP
+.EE
+.in
+.P
+We then create another child cgroup in the
+.I freezer
+hierarchy and put the shell into that cgroup:
+.P
+.in +4n
+.EX
+# \fBmkdir \-p /sys/fs/cgroup/freezer/sub\fP
+# \fBecho $$\fP                      # Show PID of this shell
+30655
+# \fBecho 30655 > /sys/fs/cgroup/freezer/sub/cgroup.procs\fP
+# \fBcat /proc/self/cgroup | grep freezer\fP
+7:freezer:/sub
+.EE
+.in
+.P
+Next, we use
+.BR unshare (1)
+to create a process running a new shell in new cgroup and mount namespaces:
+.P
+.in +4n
+.EX
+# \fBPS1="sh2# " unshare \-Cm bash\fP
+.EE
+.in
+.P
+From the new shell started by
+.BR unshare (1),
+we then inspect the
+.IR /proc/ pid /cgroup
+files of, respectively, the new shell,
+a process that is in the initial cgroup namespace
+.RI ( init ,
+with PID 1), and the process in the sibling cgroup
+.RI ( sub2 ):
+.P
+.in +4n
+.EX
+sh2# \fBcat /proc/self/cgroup | grep freezer\fP
+7:freezer:/
+sh2# \fBcat /proc/1/cgroup | grep freezer\fP
+7:freezer:/..
+sh2# \fBcat /proc/20124/cgroup | grep freezer\fP
+7:freezer:/../sub2
+.EE
+.in
+.P
+From the output of the first command,
+we see that the freezer cgroup membership of the new shell
+(which is in the same cgroup as the initial shell)
+is shown defined relative to the freezer cgroup root directory
+that was established when the new cgroup namespace was created.
+(In absolute terms,
+the new shell is in the
+.I /sub
+freezer cgroup,
+and the root directory of the freezer cgroup hierarchy
+in the new cgroup namespace is also
+.IR /sub .
+Thus, the new shell's cgroup membership is displayed as \[aq]/\[aq].)
+.P
+However, when we look in
+.I /proc/self/mountinfo
+we see the following anomaly:
+.P
+.in +4n
+.EX
+sh2# \fBcat /proc/self/mountinfo | grep freezer\fP
+155 145 0:32 /.. /sys/fs/cgroup/freezer ...
+.EE
+.in
+.P
+The fourth field of this line
+.RI ( /.. )
+should show the
+directory in the cgroup filesystem which forms the root of this mount.
+Since by the definition of cgroup namespaces, the process's current
+freezer cgroup directory became its root freezer cgroup directory,
+we should see \[aq]/\[aq] in this field.
+The problem here is that we are seeing a mount entry for the cgroup
+filesystem corresponding to the initial cgroup namespace
+(whose cgroup filesystem is indeed rooted at the parent directory of
+.IR sub ).
+To fix this problem, we must remount the freezer cgroup filesystem
+from the new shell (i.e., perform the mount from a process that is in the
+new cgroup namespace), after which we see the expected results:
+.P
+.in +4n
+.EX
+sh2# \fBmount \-\-make\-rslave /\fP     # Don\[aq]t propagate mount events
+                               # to other namespaces
+sh2# \fBumount /sys/fs/cgroup/freezer\fP
+sh2# \fBmount \-t cgroup \-o freezer freezer /sys/fs/cgroup/freezer\fP
+sh2# \fBcat /proc/self/mountinfo | grep freezer\fP
+155 145 0:32 / /sys/fs/cgroup/freezer rw,relatime ...
+.EE
+.in
+.\"
+.SH STANDARDS
+Linux.
+.SH NOTES
+Use of cgroup namespaces requires a kernel that is configured with the
+.B CONFIG_CGROUPS
+option.
+.P
+The virtualization provided by cgroup namespaces serves a number of purposes:
+.IP \[bu] 3
+It prevents information leaks whereby cgroup directory paths outside of
+a container would otherwise be visible to processes in the container.
+Such leakages could, for example,
+reveal information about the container framework
+to containerized applications.
+.IP \[bu]
+It eases tasks such as container migration.
+The virtualization provided by cgroup namespaces
+allows containers to be isolated from knowledge of
+the pathnames of ancestor cgroups.
+Without such isolation, the full cgroup pathnames (displayed in
+.IR /proc/self/cgroups )
+would need to be replicated on the target system when migrating a container;
+those pathnames would also need to be unique,
+so that they don't conflict with other pathnames on the target system.
+.IP \[bu]
+It allows better confinement of containerized processes,
+because it is possible to mount the container's cgroup filesystems such that
+the container processes can't gain access to ancestor cgroup directories.
+Consider, for example, the following scenario:
+.RS
+.IP \[bu] 3
+We have a cgroup directory,
+.IR /cg/1 ,
+that is owned by user ID 9000.
+.IP \[bu]
+We have a process,
+.IR X ,
+also owned by user ID 9000,
+that is namespaced under the cgroup
+.I /cg/1/2
+(i.e.,
+.I X
+was placed in a new cgroup namespace via
+.BR clone (2)
+or
+.BR unshare (2)
+with the
+.B CLONE_NEWCGROUP
+flag).
+.RE
+.IP
+In the absence of cgroup namespacing, because the cgroup directory
+.I /cg/1
+is owned (and writable) by UID 9000 and process
+.I X
+is also owned by user ID 9000, process
+.I X
+would be able to modify the contents of cgroups files
+(i.e., change cgroup settings) not only in
+.I /cg/1/2
+but also in the ancestor cgroup directory
+.IR /cg/1 .
+Namespacing process
+.I X
+under the cgroup directory
+.IR /cg/1/2 ,
+in combination with suitable mount operations
+for the cgroup filesystem (as shown above),
+prevents it modifying files in
+.IR /cg/1 ,
+since it cannot even see the contents of that directory
+(or of further removed cgroup ancestor directories).
+Combined with correct enforcement of hierarchical limits,
+this prevents process
+.I X
+from escaping the limits imposed by ancestor cgroups.
+.SH SEE ALSO
+.BR unshare (1),
+.BR clone (2),
+.BR setns (2),
+.BR unshare (2),
+.BR proc (5),
+.BR cgroups (7),
+.BR credentials (7),
+.BR namespaces (7),
+.BR user_namespaces (7)
diff --git a/man/man7/cgroups.7 b/man/man7/cgroups.7
new file mode 100644
index 000000000..877aae03f
--- /dev/null
+++ b/man/man7/cgroups.7
@@ -0,0 +1,1914 @@
+.\" Copyright (C) 2015 Serge Hallyn <serge@hallyn.com>
+.\" and Copyright (C) 2016, 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH cgroups 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cgroups \- Linux control groups
+.SH DESCRIPTION
+Control groups, usually referred to as cgroups,
+are a Linux kernel feature which allow processes to
+be organized into hierarchical groups whose usage of
+various types of resources can then be limited and monitored.
+The kernel's cgroup interface is provided through
+a pseudo-filesystem called cgroupfs.
+Grouping is implemented in the core cgroup kernel code,
+while resource tracking and limits are implemented in
+a set of per-resource-type subsystems (memory, CPU, and so on).
+.\"
+.SS Terminology
+A
+.I cgroup
+is a collection of processes that are bound to a set of
+limits or parameters defined via the cgroup filesystem.
+.P
+A
+.I subsystem
+is a kernel component that modifies the behavior of
+the processes in a cgroup.
+Various subsystems have been implemented, making it possible to do things
+such as limiting the amount of CPU time and memory available to a cgroup,
+accounting for the CPU time used by a cgroup,
+and freezing and resuming execution of the processes in a cgroup.
+Subsystems are sometimes also known as
+.I resource controllers
+(or simply, controllers).
+.P
+The cgroups for a controller are arranged in a
+.IR hierarchy .
+This hierarchy is defined by creating, removing, and
+renaming subdirectories within the cgroup filesystem.
+At each level of the hierarchy, attributes (e.g., limits) can be defined.
+The limits, control, and accounting provided by cgroups generally have
+effect throughout the subhierarchy underneath the cgroup where the
+attributes are defined.
+Thus, for example, the limits placed on
+a cgroup at a higher level in the hierarchy cannot be exceeded
+by descendant cgroups.
+.\"
+.SS Cgroups version 1 and version 2
+The initial release of the cgroups implementation was in Linux 2.6.24.
+Over time, various cgroup controllers have been added
+to allow the management of various types of resources.
+However, the development of these controllers was largely uncoordinated,
+with the result that many inconsistencies arose between controllers
+and management of the cgroup hierarchies became rather complex.
+A longer description of these problems can be found in the kernel
+source file
+.I Documentation/admin\-guide/cgroup\-v2.rst
+(or
+.I Documentation/cgroup\-v2.txt
+in Linux 4.17 and earlier).
+.P
+Because of the problems with the initial cgroups implementation
+(cgroups version 1),
+starting in Linux 3.10, work began on a new,
+orthogonal implementation to remedy these problems.
+Initially marked experimental, and hidden behind the
+.I "\-o\ __DEVEL__sane_behavior"
+mount option, the new version (cgroups version 2)
+was eventually made official with the release of Linux 4.5.
+Differences between the two versions are described in the text below.
+The file
+.IR cgroup.sane_behavior ,
+present in cgroups v1, is a relic of this mount option.
+The file always reports "0" and is only retained for backward compatibility.
+.P
+Although cgroups v2 is intended as a replacement for cgroups v1,
+the older system continues to exist
+(and for compatibility reasons is unlikely to be removed).
+Currently, cgroups v2 implements only a subset of the controllers
+available in cgroups v1.
+The two systems are implemented so that both v1 controllers and
+v2 controllers can be mounted on the same system.
+Thus, for example, it is possible to use those controllers
+that are supported under version 2,
+while also using version 1 controllers
+where version 2 does not yet support those controllers.
+The only restriction here is that a controller can't be simultaneously
+employed in both a cgroups v1 hierarchy and in the cgroups v2 hierarchy.
+.\"
+.SH CGROUPS VERSION 1
+Under cgroups v1, each controller may be mounted against a separate
+cgroup filesystem that provides its own hierarchical organization of the
+processes on the system.
+It is also possible to comount multiple (or even all) cgroups v1 controllers
+against the same cgroup filesystem, meaning that the comounted controllers
+manage the same hierarchical organization of processes.
+.P
+For each mounted hierarchy,
+the directory tree mirrors the control group hierarchy.
+Each control group is represented by a directory, with each of its child
+control cgroups represented as a child directory.
+For instance,
+.I /user/joe/1.session
+represents control group
+.IR 1.session ,
+which is a child of cgroup
+.IR joe ,
+which is a child of
+.IR /user .
+Under each cgroup directory is a set of files which can be read or
+written to, reflecting resource limits and a few general cgroup
+properties.
+.\"
+.SS Tasks (threads) versus processes
+In cgroups v1, a distinction is drawn between
+.I processes
+and
+.IR tasks .
+In this view, a process can consist of multiple tasks
+(more commonly called threads, from a user-space perspective,
+and called such in the remainder of this man page).
+In cgroups v1, it is possible to independently manipulate
+the cgroup memberships of the threads in a process.
+.P
+The cgroups v1 ability to split threads across different cgroups
+caused problems in some cases.
+For example, it made no sense for the
+.I memory
+controller,
+since all of the threads of a process share a single address space.
+Because of these problems,
+the ability to independently manipulate the cgroup memberships
+of the threads in a process was removed in the initial cgroups v2
+implementation, and subsequently restored in a more limited form
+(see the discussion of "thread mode" below).
+.\"
+.SS Mounting v1 controllers
+The use of cgroups requires a kernel built with the
+.B CONFIG_CGROUP
+option.
+In addition, each of the v1 controllers has an associated
+configuration option that must be set in order to employ that controller.
+.P
+In order to use a v1 controller,
+it must be mounted against a cgroup filesystem.
+The usual place for such mounts is under a
+.BR tmpfs (5)
+filesystem mounted at
+.IR /sys/fs/cgroup .
+Thus, one might mount the
+.I cpu
+controller as follows:
+.P
+.in +4n
+.EX
+mount \-t cgroup \-o cpu none /sys/fs/cgroup/cpu
+.EE
+.in
+.P
+It is possible to comount multiple controllers against the same hierarchy.
+For example, here the
+.I cpu
+and
+.I cpuacct
+controllers are comounted against a single hierarchy:
+.P
+.in +4n
+.EX
+mount \-t cgroup \-o cpu,cpuacct none /sys/fs/cgroup/cpu,cpuacct
+.EE
+.in
+.P
+Comounting controllers has the effect that a process is in the same cgroup for
+all of the comounted controllers.
+Separately mounting controllers allows a process to
+be in cgroup
+.I /foo1
+for one controller while being in
+.I /foo2/foo3
+for another.
+.P
+It is possible to comount all v1 controllers against the same hierarchy:
+.P
+.in +4n
+.EX
+mount \-t cgroup \-o all cgroup /sys/fs/cgroup
+.EE
+.in
+.P
+(One can achieve the same result by omitting
+.IR "\-o all" ,
+since it is the default if no controllers are explicitly specified.)
+.P
+It is not possible to mount the same controller
+against multiple cgroup hierarchies.
+For example, it is not possible to mount both the
+.I cpu
+and
+.I cpuacct
+controllers against one hierarchy, and to mount the
+.I cpu
+controller alone against another hierarchy.
+It is possible to create multiple mount with exactly
+the same set of comounted controllers.
+However, in this case all that results is multiple mount points
+providing a view of the same hierarchy.
+.P
+Note that on many systems, the v1 controllers are automatically mounted under
+.IR /sys/fs/cgroup ;
+in particular,
+.BR systemd (1)
+automatically creates such mounts.
+.\"
+.SS Unmounting v1 controllers
+A mounted cgroup filesystem can be unmounted using the
+.BR umount (8)
+command, as in the following example:
+.P
+.in +4n
+.EX
+umount /sys/fs/cgroup/pids
+.EE
+.in
+.P
+.IR "But note well" :
+a cgroup filesystem is unmounted only if it is not busy,
+that is, it has no child cgroups.
+If this is not the case, then the only effect of the
+.BR umount (8)
+is to make the mount invisible.
+Thus, to ensure that the mount is really removed,
+one must first remove all child cgroups,
+which in turn can be done only after all member processes
+have been moved from those cgroups to the root cgroup.
+.\"
+.SS Cgroups version 1 controllers
+Each of the cgroups version 1 controllers is governed
+by a kernel configuration option (listed below).
+Additionally, the availability of the cgroups feature is governed by the
+.B CONFIG_CGROUPS
+kernel configuration option.
+.TP
+.IR cpu " (since Linux 2.6.24; " \fBCONFIG_CGROUP_SCHED\fP )
+Cgroups can be guaranteed a minimum number of "CPU shares"
+when a system is busy.
+This does not limit a cgroup's CPU usage if the CPUs are not busy.
+For further information, see
+.I Documentation/scheduler/sched\-design\-CFS.rst
+(or
+.I Documentation/scheduler/sched\-design\-CFS.txt
+in Linux 5.2 and earlier).
+.IP
+In Linux 3.2,
+this controller was extended to provide CPU "bandwidth" control.
+If the kernel is configured with
+.BR CONFIG_CFS_BANDWIDTH ,
+then within each scheduling period
+(defined via a file in the cgroup directory), it is possible to define
+an upper limit on the CPU time allocated to the processes in a cgroup.
+This upper limit applies even if there is no other competition for the CPU.
+Further information can be found in the kernel source file
+.I Documentation/scheduler/sched\-bwc.rst
+(or
+.I Documentation/scheduler/sched\-bwc.txt
+in Linux 5.2 and earlier).
+.TP
+.IR cpuacct " (since Linux 2.6.24; " \fBCONFIG_CGROUP_CPUACCT\fP )
+This provides accounting for CPU usage by groups of processes.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/cpuacct.rst
+(or
+.I Documentation/cgroup\-v1/cpuacct.txt
+in Linux 5.2 and earlier).
+.TP
+.IR cpuset " (since Linux 2.6.24; " \fBCONFIG_CPUSETS\fP )
+This cgroup can be used to bind the processes in a cgroup to
+a specified set of CPUs and NUMA nodes.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/cpusets.rst
+(or
+.I Documentation/cgroup\-v1/cpusets.txt
+in Linux 5.2 and earlier).
+.
+.TP
+.IR memory " (since Linux 2.6.25; " \fBCONFIG_MEMCG\fP )
+The memory controller supports reporting and limiting of process memory, kernel
+memory, and swap used by cgroups.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/memory.rst
+(or
+.I Documentation/cgroup\-v1/memory.txt
+in Linux 5.2 and earlier).
+.TP
+.IR devices " (since Linux 2.6.26; " \fBCONFIG_CGROUP_DEVICE\fP )
+This supports controlling which processes may create (mknod) devices as
+well as open them for reading or writing.
+The policies may be specified as allow-lists and deny-lists.
+Hierarchy is enforced, so new rules must not
+violate existing rules for the target or ancestor cgroups.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/devices.rst
+(or
+.I Documentation/cgroup\-v1/devices.txt
+in Linux 5.2 and earlier).
+.TP
+.IR freezer " (since Linux 2.6.28; " \fBCONFIG_CGROUP_FREEZER\fP )
+The
+.I freezer
+cgroup can suspend and restore (resume) all processes in a cgroup.
+Freezing a cgroup
+.I /A
+also causes its children, for example, processes in
+.IR /A/B ,
+to be frozen.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/freezer\-subsystem.rst
+(or
+.I Documentation/cgroup\-v1/freezer\-subsystem.txt
+in Linux 5.2 and earlier).
+.TP
+.IR net_cls " (since Linux 2.6.29; " \fBCONFIG_CGROUP_NET_CLASSID\fP )
+This places a classid, specified for the cgroup, on network packets
+created by a cgroup.
+These classids can then be used in firewall rules,
+as well as used to shape traffic using
+.BR tc (8).
+This applies only to packets
+leaving the cgroup, not to traffic arriving at the cgroup.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/net_cls.rst
+(or
+.I Documentation/cgroup\-v1/net_cls.txt
+in Linux 5.2 and earlier).
+.TP
+.IR blkio " (since Linux 2.6.33; " \fBCONFIG_BLK_CGROUP\fP )
+The
+.I blkio
+cgroup controls and limits access to specified block devices by
+applying IO control in the form of throttling and upper limits against leaf
+nodes and intermediate nodes in the storage hierarchy.
+.IP
+Two policies are available.
+The first is a proportional-weight time-based division
+of disk implemented with CFQ.
+This is in effect for leaf nodes using CFQ.
+The second is a throttling policy which specifies
+upper I/O rate limits on a device.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/blkio\-controller.rst
+(or
+.I Documentation/cgroup\-v1/blkio\-controller.txt
+in Linux 5.2 and earlier).
+.TP
+.IR perf_event " (since Linux 2.6.39; " \fBCONFIG_CGROUP_PERF\fP )
+This controller allows
+.I perf
+monitoring of the set of processes grouped in a cgroup.
+.IP
+Further information can be found in the kernel source files
+.TP
+.IR net_prio " (since Linux 3.3; " \fBCONFIG_CGROUP_NET_PRIO\fP )
+This allows priorities to be specified, per network interface, for cgroups.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/net_prio.rst
+(or
+.I Documentation/cgroup\-v1/net_prio.txt
+in Linux 5.2 and earlier).
+.TP
+.IR hugetlb " (since Linux 3.5; " \fBCONFIG_CGROUP_HUGETLB\fP )
+This supports limiting the use of huge pages by cgroups.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/hugetlb.rst
+(or
+.I Documentation/cgroup\-v1/hugetlb.txt
+in Linux 5.2 and earlier).
+.TP
+.IR pids " (since Linux 4.3; " \fBCONFIG_CGROUP_PIDS\fP )
+This controller permits limiting the number of process that may be created
+in a cgroup (and its descendants).
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/pids.rst
+(or
+.I Documentation/cgroup\-v1/pids.txt
+in Linux 5.2 and earlier).
+.TP
+.IR rdma " (since Linux 4.11; " \fBCONFIG_CGROUP_RDMA\fP )
+The RDMA controller permits limiting the use of
+RDMA/IB-specific resources per cgroup.
+.IP
+Further information can be found in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v1/rdma.rst
+(or
+.I Documentation/cgroup\-v1/rdma.txt
+in Linux 5.2 and earlier).
+.\"
+.SS Creating cgroups and moving processes
+A cgroup filesystem initially contains a single root cgroup, '/',
+which all processes belong to.
+A new cgroup is created by creating a directory in the cgroup filesystem:
+.P
+.in +4n
+.EX
+mkdir /sys/fs/cgroup/cpu/cg1
+.EE
+.in
+.P
+This creates a new empty cgroup.
+.P
+A process may be moved to this cgroup by writing its PID into the cgroup's
+.I cgroup.procs
+file:
+.P
+.in +4n
+.EX
+echo $$ > /sys/fs/cgroup/cpu/cg1/cgroup.procs
+.EE
+.in
+.P
+Only one PID at a time should be written to this file.
+.P
+Writing the value 0 to a
+.I cgroup.procs
+file causes the writing process to be moved to the corresponding cgroup.
+.P
+When writing a PID into the
+.IR cgroup.procs ,
+all threads in the process are moved into the new cgroup at once.
+.P
+Within a hierarchy, a process can be a member of exactly one cgroup.
+Writing a process's PID to a
+.I cgroup.procs
+file automatically removes it from the cgroup of
+which it was previously a member.
+.P
+The
+.I cgroup.procs
+file can be read to obtain a list of the processes that are
+members of a cgroup.
+The returned list of PIDs is not guaranteed to be in order.
+Nor is it guaranteed to be free of duplicates.
+(For example, a PID may be recycled while reading from the list.)
+.P
+In cgroups v1, an individual thread can be moved to
+another cgroup by writing its thread ID
+(i.e., the kernel thread ID returned by
+.BR clone (2)
+and
+.BR gettid (2))
+to the
+.I tasks
+file in a cgroup directory.
+This file can be read to discover the set of threads
+that are members of the cgroup.
+.\"
+.SS Removing cgroups
+To remove a cgroup,
+it must first have no child cgroups and contain no (nonzombie) processes.
+So long as that is the case, one can simply
+remove the corresponding directory pathname.
+Note that files in a cgroup directory cannot and need not be
+removed.
+.\"
+.SS Cgroups v1 release notification
+Two files can be used to determine whether the kernel provides
+notifications when a cgroup becomes empty.
+A cgroup is considered to be empty when it contains no child
+cgroups and no member processes.
+.P
+A special file in the root directory of each cgroup hierarchy,
+.IR release_agent ,
+can be used to register the pathname of a program that may be invoked when
+a cgroup in the hierarchy becomes empty.
+The pathname of the newly empty cgroup (relative to the cgroup mount point)
+is provided as the sole command-line argument when the
+.I release_agent
+program is invoked.
+The
+.I release_agent
+program might remove the cgroup directory,
+or perhaps repopulate it with a process.
+.P
+The default value of the
+.I release_agent
+file is empty, meaning that no release agent is invoked.
+.P
+The content of the
+.I release_agent
+file can also be specified via a mount option when the
+cgroup filesystem is mounted:
+.P
+.in +4n
+.EX
+mount \-o release_agent=pathname ...
+.EE
+.in
+.P
+Whether or not the
+.I release_agent
+program is invoked when a particular cgroup becomes empty is determined
+by the value in the
+.I notify_on_release
+file in the corresponding cgroup directory.
+If this file contains the value 0, then the
+.I release_agent
+program is not invoked.
+If it contains the value 1, the
+.I release_agent
+program is invoked.
+The default value for this file in the root cgroup is 0.
+At the time when a new cgroup is created,
+the value in this file is inherited from the corresponding file
+in the parent cgroup.
+.\"
+.SS Cgroup v1 named hierarchies
+In cgroups v1,
+it is possible to mount a cgroup hierarchy that has no attached controllers:
+.P
+.in +4n
+.EX
+mount \-t cgroup \-o none,name=somename none /some/mount/point
+.EE
+.in
+.P
+Multiple instances of such hierarchies can be mounted;
+each hierarchy must have a unique name.
+The only purpose of such hierarchies is to track processes.
+(See the discussion of release notification below.)
+An example of this is the
+.I name=systemd
+cgroup hierarchy that is used by
+.BR systemd (1)
+to track services and user sessions.
+.P
+Since Linux 5.0, the
+.I cgroup_no_v1
+kernel boot option (described below) can be used to disable cgroup v1
+named hierarchies, by specifying
+.IR cgroup_no_v1=named .
+.\"
+.SH CGROUPS VERSION 2
+In cgroups v2,
+all mounted controllers reside in a single unified hierarchy.
+While (different) controllers may be simultaneously
+mounted under the v1 and v2 hierarchies,
+it is not possible to mount the same controller simultaneously
+under both the v1 and the v2 hierarchies.
+.P
+The new behaviors in cgroups v2 are summarized here,
+and in some cases elaborated in the following subsections.
+.IP \[bu] 3
+Cgroups v2 provides a unified hierarchy against
+which all controllers are mounted.
+.IP \[bu]
+"Internal" processes are not permitted.
+With the exception of the root cgroup, processes may reside
+only in leaf nodes (cgroups that do not themselves contain child cgroups).
+The details are somewhat more subtle than this, and are described below.
+.IP \[bu]
+Active cgroups must be specified via the files
+.I cgroup.controllers
+and
+.IR cgroup.subtree_control .
+.IP \[bu]
+The
+.I tasks
+file has been removed.
+In addition, the
+.I cgroup.clone_children
+file that is employed by the
+.I cpuset
+controller has been removed.
+.IP \[bu]
+An improved mechanism for notification of empty cgroups is provided by the
+.I cgroup.events
+file.
+.P
+For more changes, see the
+.I Documentation/admin\-guide/cgroup\-v2.rst
+file in the kernel source
+(or
+.I Documentation/cgroup\-v2.txt
+in Linux 4.17 and earlier).
+.
+.P
+Some of the new behaviors listed above saw subsequent modification with
+the addition in Linux 4.14 of "thread mode" (described below).
+.\"
+.SS Cgroups v2 unified hierarchy
+In cgroups v1, the ability to mount different controllers
+against different hierarchies was intended to allow great flexibility
+for application design.
+In practice, though,
+the flexibility turned out to be less useful than expected,
+and in many cases added complexity.
+Therefore, in cgroups v2,
+all available controllers are mounted against a single hierarchy.
+The available controllers are automatically mounted,
+meaning that it is not necessary (or possible) to specify the controllers
+when mounting the cgroup v2 filesystem using a command such as the following:
+.P
+.in +4n
+.EX
+mount \-t cgroup2 none /mnt/cgroup2
+.EE
+.in
+.P
+A cgroup v2 controller is available only if it is not currently in use
+via a mount against a cgroup v1 hierarchy.
+Or, to put things another way, it is not possible to employ
+the same controller against both a v1 hierarchy and the unified v2 hierarchy.
+This means that it may be necessary first to unmount a v1 controller
+(as described above) before that controller is available in v2.
+Since
+.BR systemd (1)
+makes heavy use of some v1 controllers by default,
+it can in some cases be simpler to boot the system with
+selected v1 controllers disabled.
+To do this, specify the
+.I cgroup_no_v1=list
+option on the kernel boot command line;
+.I list
+is a comma-separated list of the names of the controllers to disable,
+or the word
+.I all
+to disable all v1 controllers.
+(This situation is correctly handled by
+.BR systemd (1),
+which falls back to operating without the specified controllers.)
+.P
+Note that on many modern systems,
+.BR systemd (1)
+automatically mounts the
+.I cgroup2
+filesystem at
+.I /sys/fs/cgroup/unified
+during the boot process.
+.\"
+.SS Cgroups v2 mount options
+The following options
+.RI ( mount\~\-o )
+can be specified when mounting the group v2 filesystem:
+.TP
+.IR nsdelegate " (since Linux 4.15)"
+Treat cgroup namespaces as delegation boundaries.
+For details, see below.
+.TP
+.IR memory_localevents " (since Linux 5.2)"
+.\" commit 9852ae3fe5293264f01c49f2571ef7688f7823ce
+The
+.I memory.events
+should show statistics only for the cgroup itself,
+and not for any descendant cgroups.
+This was the behavior before Linux 5.2.
+Starting in Linux 5.2,
+the default behavior is to include statistics for descendant cgroups in
+.IR memory.events ,
+and this mount option can be used to revert to the legacy behavior.
+This option is system wide and can be set on mount or
+modified through remount only from the initial mount namespace;
+it is silently ignored in noninitial namespaces.
+.\"
+.SS Cgroups v2 controllers
+The following controllers, documented in the kernel source file
+.I Documentation/admin\-guide/cgroup\-v2.rst
+(or
+.I Documentation/cgroup\-v2.txt
+in Linux 4.17 and earlier),
+are supported in cgroups version 2:
+.TP
+.IR cpu " (since Linux 4.15)"
+This is the successor to the version 1
+.I cpu
+and
+.I cpuacct
+controllers.
+.TP
+.IR cpuset " (since Linux 5.0)"
+This is the successor of the version 1
+.I cpuset
+controller.
+.TP
+.IR freezer " (since Linux 5.2)"
+.\" commit 76f969e8948d82e78e1bc4beb6b9465908e74873
+This is the successor of the version 1
+.I freezer
+controller.
+.TP
+.IR hugetlb " (since Linux 5.6)"
+This is the successor of the version 1
+.I hugetlb
+controller.
+.TP
+.IR io " (since Linux 4.5)"
+This is the successor of the version 1
+.I blkio
+controller.
+.TP
+.IR memory " (since Linux 4.5)"
+This is the successor of the version 1
+.I memory
+controller.
+.TP
+.IR perf_event " (since Linux 4.11)"
+This is the same as the version 1
+.I perf_event
+controller.
+.TP
+.IR pids " (since Linux 4.5)"
+This is the same as the version 1
+.I pids
+controller.
+.TP
+.IR rdma " (since Linux 4.11)"
+This is the same as the version 1
+.I rdma
+controller.
+.P
+There is no direct equivalent of the
+.I net_cls
+and
+.I net_prio
+controllers from cgroups version 1.
+Instead, support has been added to
+.BR iptables (8)
+to allow eBPF filters that hook on cgroup v2 pathnames to make decisions
+about network traffic on a per-cgroup basis.
+.P
+The v2
+.I devices
+controller provides no interface files;
+instead, device control is gated by attaching an eBPF
+.RB ( BPF_CGROUP_DEVICE )
+program to a v2 cgroup.
+.\"
+.SS Cgroups v2 subtree control
+Each cgroup in the v2 hierarchy contains the following two files:
+.TP
+.I cgroup.controllers
+This read-only file exposes a list of the controllers that are
+.I available
+in this cgroup.
+The contents of this file match the contents of the
+.I cgroup.subtree_control
+file in the parent cgroup.
+.TP
+.I cgroup.subtree_control
+This is a list of controllers that are
+.I active
+.RI ( enabled )
+in the cgroup.
+The set of controllers in this file is a subset of the set in the
+.I cgroup.controllers
+of this cgroup.
+The set of active controllers is modified by writing strings to this file
+containing space-delimited controller names,
+each preceded by '+' (to enable a controller)
+or '\-' (to disable a controller), as in the following example:
+.IP
+.in +4n
+.EX
+echo \[aq]+pids \-memory\[aq] > x/y/cgroup.subtree_control
+.EE
+.in
+.IP
+An attempt to enable a controller
+that is not present in
+.I cgroup.controllers
+leads to an
+.B ENOENT
+error when writing to the
+.I cgroup.subtree_control
+file.
+.P
+Because the list of controllers in
+.I cgroup.subtree_control
+is a subset of those
+.IR cgroup.controllers ,
+a controller that has been disabled in one cgroup in the hierarchy
+can never be re-enabled in the subtree below that cgroup.
+.P
+A cgroup's
+.I cgroup.subtree_control
+file determines the set of controllers that are exercised in the
+.I child
+cgroups.
+When a controller (e.g.,
+.IR pids )
+is present in the
+.I cgroup.subtree_control
+file of a parent cgroup,
+then the corresponding controller-interface files (e.g.,
+.IR pids.max )
+are automatically created in the children of that cgroup
+and can be used to exert resource control in the child cgroups.
+.\"
+.SS Cgroups v2 \[dq]no internal processes\[dq] rule
+Cgroups v2 enforces a so-called "no internal processes" rule.
+Roughly speaking, this rule means that,
+with the exception of the root cgroup, processes may reside
+only in leaf nodes (cgroups that do not themselves contain child cgroups).
+This avoids the need to decide how to partition resources between
+processes which are members of cgroup A and processes in child cgroups of A.
+.P
+For instance, if cgroup
+.I /cg1/cg2
+exists, then a process may reside in
+.IR /cg1/cg2 ,
+but not in
+.IR /cg1 .
+This is to avoid an ambiguity in cgroups v1
+with respect to the delegation of resources between processes in
+.I /cg1
+and its child cgroups.
+The recommended approach in cgroups v2 is to create a subdirectory called
+.I leaf
+for any nonleaf cgroup which should contain processes, but no child cgroups.
+Thus, processes which previously would have gone into
+.I /cg1
+would now go into
+.IR /cg1/leaf .
+This has the advantage of making explicit
+the relationship between processes in
+.I /cg1/leaf
+and
+.IR /cg1 's
+other children.
+.P
+The "no internal processes" rule is in fact more subtle than stated above.
+More precisely, the rule is that a (nonroot) cgroup can't both
+(1) have member processes, and
+(2) distribute resources into child cgroups\[em]that is, have a nonempty
+.I cgroup.subtree_control
+file.
+Thus, it
+.I is
+possible for a cgroup to have both member processes and child cgroups,
+but before controllers can be enabled for that cgroup,
+the member processes must be moved out of the cgroup
+(e.g., perhaps into the child cgroups).
+.P
+With the Linux 4.14 addition of "thread mode" (described below),
+the "no internal processes" rule has been relaxed in some cases.
+.\"
+.SS Cgroups v2 cgroup.events file
+Each nonroot cgroup in the v2 hierarchy contains a read-only file,
+.IR cgroup.events ,
+whose contents are key-value pairs
+(delimited by newline characters, with the key and value separated by spaces)
+providing state information about the cgroup:
+.P
+.in +4n
+.EX
+$ \fBcat mygrp/cgroup.events\fP
+populated 1
+frozen 0
+.EE
+.in
+.P
+The following keys may appear in this file:
+.TP
+.I populated
+The value of this key is either 1,
+if this cgroup or any of its descendants has member processes,
+or otherwise 0.
+.TP
+.IR frozen " (since Linux 5.2)"
+.\" commit 76f969e8948d82e78e1bc4beb6b9465908e7487
+The value of this key is 1 if this cgroup is currently frozen,
+or 0 if it is not.
+.P
+The
+.I cgroup.events
+file can be monitored, in order to receive notification when the value of
+one of its keys changes.
+Such monitoring can be done using
+.BR inotify (7),
+which notifies changes as
+.B IN_MODIFY
+events, or
+.BR poll (2),
+which notifies changes by returning the
+.B POLLPRI
+and
+.B POLLERR
+bits in the
+.I revents
+field.
+.\"
+.SS Cgroup v2 release notification
+Cgroups v2 provides a new mechanism for obtaining notification
+when a cgroup becomes empty.
+The cgroups v1
+.I release_agent
+and
+.I notify_on_release
+files are removed, and replaced by the
+.I populated
+key in the
+.I cgroup.events
+file.
+This key either has the value 0,
+meaning that the cgroup (and its descendants)
+contain no (nonzombie) member processes,
+or 1, meaning that the cgroup (or one of its descendants)
+contains member processes.
+.P
+The cgroups v2 release-notification mechanism
+offers the following advantages over the cgroups v1
+.I release_agent
+mechanism:
+.IP \[bu] 3
+It allows for cheaper notification,
+since a single process can monitor multiple
+.I cgroup.events
+files (using the techniques described earlier).
+By contrast, the cgroups v1 mechanism requires the expense of creating
+a process for each notification.
+.IP \[bu]
+Notification for different cgroup subhierarchies can be delegated
+to different processes.
+By contrast, the cgroups v1 mechanism allows only one release agent
+for an entire hierarchy.
+.\"
+.SS Cgroups v2 cgroup.stat file
+.\" commit ec39225cca42c05ac36853d11d28f877fde5c42e
+Each cgroup in the v2 hierarchy contains a read-only
+.I cgroup.stat
+file (first introduced in Linux 4.14)
+that consists of lines containing key-value pairs.
+The following keys currently appear in this file:
+.TP
+.I nr_descendants
+This is the total number of visible (i.e., living) descendant cgroups
+underneath this cgroup.
+.TP
+.I nr_dying_descendants
+This is the total number of dying descendant cgroups
+underneath this cgroup.
+A cgroup enters the dying state after being deleted.
+It remains in that state for an undefined period
+(which will depend on system load)
+while resources are freed before the cgroup is destroyed.
+Note that the presence of some cgroups in the dying state is normal,
+and is not indicative of any problem.
+.IP
+A process can't be made a member of a dying cgroup,
+and a dying cgroup can't be brought back to life.
+.\"
+.SS Limiting the number of descendant cgroups
+Each cgroup in the v2 hierarchy contains the following files,
+which can be used to view and set limits on the number
+of descendant cgroups under that cgroup:
+.TP
+.IR cgroup.max.depth " (since Linux 4.14)"
+.\" commit 1a926e0bbab83bae8207d05a533173425e0496d1
+This file defines a limit on the depth of nesting of descendant cgroups.
+A value of 0 in this file means that no descendant cgroups can be created.
+An attempt to create a descendant whose nesting level exceeds
+the limit fails
+.RI ( mkdir (2)
+fails with the error
+.BR EAGAIN ).
+.IP
+Writing the string
+.I \[dq]max\[dq]
+to this file means that no limit is imposed.
+The default value in this file is
+.IR \[dq]max\[dq] .
+.TP
+.IR cgroup.max.descendants " (since Linux 4.14)"
+.\" commit 1a926e0bbab83bae8207d05a533173425e0496d1
+This file defines a limit on the number of live descendant cgroups that
+this cgroup may have.
+An attempt to create more descendants than allowed by the limit fails
+.RI ( mkdir (2)
+fails with the error
+.BR EAGAIN ).
+.IP
+Writing the string
+.I \[dq]max\[dq]
+to this file means that no limit is imposed.
+The default value in this file is
+.IR \[dq]max\[dq] .
+.\"
+.SH CGROUPS DELEGATION: DELEGATING A HIERARCHY TO A LESS PRIVILEGED USER
+In the context of cgroups,
+delegation means passing management of some subtree
+of the cgroup hierarchy to a nonprivileged user.
+Cgroups v1 provides support for delegation based on file permissions
+in the cgroup hierarchy but with less strict containment rules than v2
+(as noted below).
+Cgroups v2 supports delegation with containment by explicit design.
+The focus of the discussion in this section is on delegation in cgroups v2,
+with some differences for cgroups v1 noted along the way.
+.P
+Some terminology is required in order to describe delegation.
+A
+.I delegater
+is a privileged user (i.e., root) who owns a parent cgroup.
+A
+.I delegatee
+is a nonprivileged user who will be granted the permissions needed
+to manage some subhierarchy under that parent cgroup,
+known as the
+.IR "delegated subtree" .
+.P
+To perform delegation,
+the delegater makes certain directories and files writable by the delegatee,
+typically by changing the ownership of the objects to be the user ID
+of the delegatee.
+Assuming that we want to delegate the hierarchy rooted at (say)
+.I /dlgt_grp
+and that there are not yet any child cgroups under that cgroup,
+the ownership of the following is changed to the user ID of the delegatee:
+.TP
+.I /dlgt_grp
+Changing the ownership of the root of the subtree means that any new
+cgroups created under the subtree (and the files they contain)
+will also be owned by the delegatee.
+.TP
+.I /dlgt_grp/cgroup.procs
+Changing the ownership of this file means that the delegatee
+can move processes into the root of the delegated subtree.
+.TP
+.IR /dlgt_grp/cgroup.subtree_control " (cgroups v2 only)"
+Changing the ownership of this file means that the delegatee
+can enable controllers (that are present in
+.IR /dlgt_grp/cgroup.controllers )
+in order to further redistribute resources at lower levels in the subtree.
+(As an alternative to changing the ownership of this file,
+the delegater might instead add selected controllers to this file.)
+.TP
+.IR /dlgt_grp/cgroup.threads " (cgroups v2 only)"
+Changing the ownership of this file is necessary if a threaded subtree
+is being delegated (see the description of "thread mode", below).
+This permits the delegatee to write thread IDs to the file.
+(The ownership of this file can also be changed when delegating
+a domain subtree, but currently this serves no purpose,
+since, as described below, it is not possible to move a thread between
+domain cgroups by writing its thread ID to the
+.I cgroup.threads
+file.)
+.IP
+In cgroups v1, the corresponding file that should instead be delegated is the
+.I tasks
+file.
+.P
+The delegater should
+.I not
+change the ownership of any of the controller interfaces files (e.g.,
+.IR pids.max ,
+.IR memory.high )
+in
+.IR dlgt_grp .
+Those files are used from the next level above the delegated subtree
+in order to distribute resources into the subtree,
+and the delegatee should not have permission to change
+the resources that are distributed into the delegated subtree.
+.P
+See also the discussion of the
+.I /sys/kernel/cgroup/delegate
+file in NOTES for information about further delegatable files in cgroups v2.
+.P
+After the aforementioned steps have been performed,
+the delegatee can create child cgroups within the delegated subtree
+(the cgroup subdirectories and the files they contain
+will be owned by the delegatee)
+and move processes between cgroups in the subtree.
+If some controllers are present in
+.IR dlgt_grp/cgroup.subtree_control ,
+or the ownership of that file was passed to the delegatee,
+the delegatee can also control the further redistribution
+of the corresponding resources into the delegated subtree.
+.\"
+.SS Cgroups v2 delegation: nsdelegate and cgroup namespaces
+Starting with Linux 4.13,
+.\" commit 5136f6365ce3eace5a926e10f16ed2a233db5ba9
+there is a second way to perform cgroup delegation in the cgroups v2 hierarchy.
+This is done by mounting or remounting the cgroup v2 filesystem with the
+.I nsdelegate
+mount option.
+For example, if the cgroup v2 filesystem has already been mounted,
+we can remount it with the
+.I nsdelegate
+option as follows:
+.P
+.in +4n
+.EX
+mount \-t cgroup2 \-o remount,nsdelegate \e
+                 none /sys/fs/cgroup/unified
+.EE
+.in
+.\"
+.\" Alternatively, we could boot the kernel with the options:
+.\"
+.\"    cgroup_no_v1=all systemd.legacy_systemd_cgroup_controller
+.\"
+.\" The effect of the latter option is to prevent systemd from employing
+.\" its "hybrid" cgroup mode, where it tries to make use of cgroups v2.
+.P
+The effect of this mount option is to cause cgroup namespaces
+to automatically become delegation boundaries.
+More specifically,
+the following restrictions apply for processes inside the cgroup namespace:
+.IP \[bu] 3
+Writes to controller interface files in the root directory of the namespace
+will fail with the error
+.BR EPERM .
+Processes inside the cgroup namespace can still write to delegatable
+files in the root directory of the cgroup namespace such as
+.I cgroup.procs
+and
+.IR cgroup.subtree_control ,
+and can create subhierarchy underneath the root directory.
+.IP \[bu]
+Attempts to migrate processes across the namespace boundary are denied
+(with the error
+.BR ENOENT ).
+Processes inside the cgroup namespace can still
+(subject to the containment rules described below)
+move processes between cgroups
+.I within
+the subhierarchy under the namespace root.
+.P
+The ability to define cgroup namespaces as delegation boundaries
+makes cgroup namespaces more useful.
+To understand why, suppose that we already have one cgroup hierarchy
+that has been delegated to a nonprivileged user,
+.IR cecilia ,
+using the older delegation technique described above.
+Suppose further that
+.I cecilia
+wanted to further delegate a subhierarchy
+under the existing delegated hierarchy.
+(For example, the delegated hierarchy might be associated with
+an unprivileged container run by
+.IR cecilia .)
+Even if a cgroup namespace was employed,
+because both hierarchies are owned by the unprivileged user
+.IR cecilia ,
+the following illegitimate actions could be performed:
+.IP \[bu] 3
+A process in the inferior hierarchy could change the
+resource controller settings in the root directory of that hierarchy.
+(These resource controller settings are intended to allow control to
+be exercised from the
+.I parent
+cgroup;
+a process inside the child cgroup should not be allowed to modify them.)
+.IP \[bu]
+A process inside the inferior hierarchy could move processes
+into and out of the inferior hierarchy if the cgroups in the
+superior hierarchy were somehow visible.
+.P
+Employing the
+.I nsdelegate
+mount option prevents both of these possibilities.
+.P
+The
+.I nsdelegate
+mount option only has an effect when performed in
+the initial mount namespace;
+in other mount namespaces, the option is silently ignored.
+.P
+.IR Note :
+On some systems,
+.BR systemd (1)
+automatically mounts the cgroup v2 filesystem.
+In order to experiment with the
+.I nsdelegate
+operation, it may be useful to boot the kernel with
+the following command-line options:
+.P
+.in +4n
+.EX
+cgroup_no_v1=all systemd.legacy_systemd_cgroup_controller
+.EE
+.in
+.P
+These options cause the kernel to boot with the cgroups v1 controllers
+disabled (meaning that the controllers are available in the v2 hierarchy),
+and tells
+.BR systemd (1)
+not to mount and use the cgroup v2 hierarchy,
+so that the v2 hierarchy can be manually mounted
+with the desired options after boot-up.
+.\"
+.SS Cgroup delegation containment rules
+Some delegation
+.I containment rules
+ensure that the delegatee can move processes between cgroups within the
+delegated subtree,
+but can't move processes from outside the delegated subtree into
+the subtree or vice versa.
+A nonprivileged process (i.e., the delegatee) can write the PID of
+a "target" process into a
+.I cgroup.procs
+file only if all of the following are true:
+.IP \[bu] 3
+The writer has write permission on the
+.I cgroup.procs
+file in the destination cgroup.
+.IP \[bu]
+The writer has write permission on the
+.I cgroup.procs
+file in the nearest common ancestor of the source and destination cgroups.
+Note that in some cases,
+the nearest common ancestor may be the source or destination cgroup itself.
+This requirement is not enforced for cgroups v1 hierarchies,
+with the consequence that containment in v1 is less strict than in v2.
+(For example, in cgroups v1 the user that owns two distinct
+delegated subhierarchies can move a process between the hierarchies.)
+.IP \[bu]
+If the cgroup v2 filesystem was mounted with the
+.I nsdelegate
+option, the writer must be able to see the source and destination cgroups
+from its cgroup namespace.
+.IP \[bu]
+In cgroups v1:
+the effective UID of the writer (i.e., the delegatee) matches the
+real user ID or the saved set-user-ID of the target process.
+Before Linux 4.11,
+.\" commit 576dd464505fc53d501bb94569db76f220104d28
+this requirement also applied in cgroups v2
+(This was a historical requirement inherited from cgroups v1
+that was later deemed unnecessary,
+since the other rules suffice for containment in cgroups v2.)
+.P
+.IR Note :
+one consequence of these delegation containment rules is that the
+unprivileged delegatee can't place the first process into
+the delegated subtree;
+instead, the delegater must place the first process
+(a process owned by the delegatee) into the delegated subtree.
+.\"
+.SH CGROUPS VERSION 2 THREAD MODE
+Among the restrictions imposed by cgroups v2 that were not present
+in cgroups v1 are the following:
+.IP \[bu] 3
+.IR "No thread-granularity control" :
+all of the threads of a process must be in the same cgroup.
+.IP \[bu]
+.IR "No internal processes" :
+a cgroup can't both have member processes and
+exercise controllers on child cgroups.
+.P
+Both of these restrictions were added because
+the lack of these restrictions had caused problems
+in cgroups v1.
+In particular, the cgroups v1 ability to allow thread-level granularity
+for cgroup membership made no sense for some controllers.
+(A notable example was the
+.I memory
+controller: since threads share an address space,
+it made no sense to split threads across different
+.I memory
+cgroups.)
+.P
+Notwithstanding the initial design decision in cgroups v2,
+there were use cases for certain controllers, notably the
+.I cpu
+controller,
+for which thread-level granularity of control was meaningful and useful.
+To accommodate such use cases, Linux 4.14 added
+.I "thread mode"
+for cgroups v2.
+.P
+Thread mode allows the following:
+.IP \[bu] 3
+The creation of
+.I threaded subtrees
+in which the threads of a process may
+be spread across cgroups inside the tree.
+(A threaded subtree may contain multiple multithreaded processes.)
+.IP \[bu]
+The concept of
+.IR "threaded controllers" ,
+which can distribute resources across the cgroups in a threaded subtree.
+.IP \[bu]
+A relaxation of the "no internal processes rule",
+so that, within a threaded subtree,
+a cgroup can both contain member threads and
+exercise resource control over child cgroups.
+.P
+With the addition of thread mode,
+each nonroot cgroup now contains a new file,
+.IR cgroup.type ,
+that exposes, and in some circumstances can be used to change,
+the "type" of a cgroup.
+This file contains one of the following type values:
+.TP
+.I domain
+This is a normal v2 cgroup that provides process-granularity control.
+If a process is a member of this cgroup,
+then all threads of the process are (by definition) in the same cgroup.
+This is the default cgroup type,
+and provides the same behavior that was provided for
+cgroups in the initial cgroups v2 implementation.
+.TP
+.I threaded
+This cgroup is a member of a threaded subtree.
+Threads can be added to this cgroup,
+and controllers can be enabled for the cgroup.
+.TP
+.I domain threaded
+This is a domain cgroup that serves as the root of a threaded subtree.
+This cgroup type is also known as "threaded root".
+.TP
+.I domain invalid
+This is a cgroup inside a threaded subtree
+that is in an "invalid" state.
+Processes can't be added to the cgroup,
+and controllers can't be enabled for the cgroup.
+The only thing that can be done with this cgroup (other than deleting it)
+is to convert it to a
+.I threaded
+cgroup by writing the string
+.I \[dq]threaded\[dq]
+to the
+.I cgroup.type
+file.
+.IP
+The rationale for the existence of this "interim" type
+during the creation of a threaded subtree
+(rather than the kernel simply immediately converting all cgroups
+under the threaded root to the type
+.IR threaded )
+is to allow for
+possible future extensions to the thread mode model
+.\"
+.SS Threaded versus domain controllers
+With the addition of threads mode,
+cgroups v2 now distinguishes two types of resource controllers:
+.IP \[bu] 3
+.I Threaded
+.\" In the kernel source, look for ".threaded[ \t]*= true" in
+.\" initializations of struct cgroup_subsys
+controllers: these controllers support thread-granularity for
+resource control and can be enabled inside threaded subtrees,
+with the result that the corresponding controller-interface files
+appear inside the cgroups in the threaded subtree.
+As at Linux 4.19, the following controllers are threaded:
+.IR cpu ,
+.IR perf_event ,
+and
+.IR pids .
+.IP \[bu]
+.I Domain
+controllers: these controllers support only process granularity
+for resource control.
+From the perspective of a domain controller,
+all threads of a process are always in the same cgroup.
+Domain controllers can't be enabled inside a threaded subtree.
+.\"
+.SS Creating a threaded subtree
+There are two pathways that lead to the creation of a threaded subtree.
+The first pathway proceeds as follows:
+.IP (1) 5
+We write the string
+.I \[dq]threaded\[dq]
+to the
+.I cgroup.type
+file of a cgroup
+.I y/z
+that currently has the type
+.IR domain .
+This has the following effects:
+.RS
+.IP \[bu] 3
+The type of the cgroup
+.I y/z
+becomes
+.IR threaded .
+.IP \[bu]
+The type of the parent cgroup,
+.IR y ,
+becomes
+.IR "domain threaded" .
+The parent cgroup is the root of a threaded subtree
+(also known as the "threaded root").
+.IP \[bu]
+All other cgroups under
+.I y
+that were not already of type
+.I threaded
+(because they were inside already existing threaded subtrees
+under the new threaded root)
+are converted to type
+.IR "domain invalid" .
+Any subsequently created cgroups under
+.I y
+will also have the type
+.IR "domain invalid" .
+.RE
+.IP (2)
+We write the string
+.I \[dq]threaded\[dq]
+to each of the
+.I domain invalid
+cgroups under
+.IR y ,
+in order to convert them to the type
+.IR threaded .
+As a consequence of this step, all threads under the threaded root
+now have the type
+.I threaded
+and the threaded subtree is now fully usable.
+The requirement to write
+.I \[dq]threaded\[dq]
+to each of these cgroups is somewhat cumbersome,
+but allows for possible future extensions to the thread-mode model.
+.P
+The second way of creating a threaded subtree is as follows:
+.IP (1) 5
+In an existing cgroup,
+.IR z ,
+that currently has the type
+.IR domain ,
+we (1.1) enable one or more threaded controllers and
+(1.2) make a process a member of
+.IR z .
+(These two steps can be done in either order.)
+This has the following consequences:
+.RS
+.IP \[bu] 3
+The type of
+.I z
+becomes
+.IR "domain threaded" .
+.IP \[bu]
+All of the descendant cgroups of
+.I z
+that were not already of type
+.I threaded
+are converted to type
+.IR "domain invalid" .
+.RE
+.IP (2)
+As before, we make the threaded subtree usable by writing the string
+.I \[dq]threaded\[dq]
+to each of the
+.I domain invalid
+cgroups under
+.IR z ,
+in order to convert them to the type
+.IR threaded .
+.P
+One of the consequences of the above pathways to creating a threaded subtree
+is that the threaded root cgroup can be a parent only to
+.I threaded
+(and
+.IR "domain invalid" )
+cgroups.
+The threaded root cgroup can't be a parent of a
+.I domain
+cgroups, and a
+.I threaded
+cgroup
+can't have a sibling that is a
+.I domain
+cgroup.
+.\"
+.SS Using a threaded subtree
+Within a threaded subtree, threaded controllers can be enabled
+in each subgroup whose type has been changed to
+.IR threaded ;
+upon doing so, the corresponding controller interface files
+appear in the children of that cgroup.
+.P
+A process can be moved into a threaded subtree by writing its PID to the
+.I cgroup.procs
+file in one of the cgroups inside the tree.
+This has the effect of making all of the threads
+in the process members of the corresponding cgroup
+and makes the process a member of the threaded subtree.
+The threads of the process can then be spread across
+the threaded subtree by writing their thread IDs (see
+.BR gettid (2))
+to the
+.I cgroup.threads
+files in different cgroups inside the subtree.
+The threads of a process must all reside in the same threaded subtree.
+.P
+As with writing to
+.IR cgroup.procs ,
+some containment rules apply when writing to the
+.I cgroup.threads
+file:
+.IP \[bu] 3
+The writer must have write permission on the
+cgroup.threads
+file in the destination cgroup.
+.IP \[bu]
+The writer must have write permission on the
+.I cgroup.procs
+file in the common ancestor of the source and destination cgroups.
+(In some cases,
+the common ancestor may be the source or destination cgroup itself.)
+.IP \[bu]
+The source and destination cgroups must be in the same threaded subtree.
+(Outside a threaded subtree, an attempt to move a thread by writing
+its thread ID to the
+.I cgroup.threads
+file in a different
+.I domain
+cgroup fails with the error
+.BR EOPNOTSUPP .)
+.P
+The
+.I cgroup.threads
+file is present in each cgroup (including
+.I domain
+cgroups) and can be read in order to discover the set of threads
+that is present in the cgroup.
+The set of thread IDs obtained when reading this file
+is not guaranteed to be ordered or free of duplicates.
+.P
+The
+.I cgroup.procs
+file in the threaded root shows the PIDs of all processes
+that are members of the threaded subtree.
+The
+.I cgroup.procs
+files in the other cgroups in the subtree are not readable.
+.P
+Domain controllers can't be enabled in a threaded subtree;
+no controller-interface files appear inside the cgroups underneath the
+threaded root.
+From the point of view of a domain controller,
+threaded subtrees are invisible:
+a multithreaded process inside a threaded subtree appears to a domain
+controller as a process that resides in the threaded root cgroup.
+.P
+Within a threaded subtree, the "no internal processes" rule does not apply:
+a cgroup can both contain member processes (or thread)
+and exercise controllers on child cgroups.
+.\"
+.SS Rules for writing to cgroup.type and creating threaded subtrees
+A number of rules apply when writing to the
+.I cgroup.type
+file:
+.IP \[bu] 3
+Only the string
+.I \[dq]threaded\[dq]
+may be written.
+In other words, the only explicit transition that is possible is to convert a
+.I domain
+cgroup to type
+.IR threaded .
+.IP \[bu]
+The effect of writing
+.I \[dq]threaded\[dq]
+depends on the current value in
+.IR cgroup.type ,
+as follows:
+.RS
+.IP \[bu] 3
+.I domain
+or
+.IR "domain threaded" :
+start the creation of a threaded subtree
+(whose root is the parent of this cgroup) via
+the first of the pathways described above;
+.IP \[bu]
+.IR "domain\ invalid" :
+convert this cgroup (which is inside a threaded subtree) to a usable (i.e.,
+.IR threaded )
+state;
+.IP \[bu]
+.IR threaded :
+no effect (a "no-op").
+.RE
+.IP \[bu]
+We can't write to a
+.I cgroup.type
+file if the parent's type is
+.IR "domain invalid" .
+In other words, the cgroups of a threaded subtree must be converted to the
+.I threaded
+state in a top-down manner.
+.P
+There are also some constraints that must be satisfied
+in order to create a threaded subtree rooted at the cgroup
+.IR x :
+.IP \[bu] 3
+There can be no member processes in the descendant cgroups of
+.IR x .
+(The cgroup
+.I x
+can itself have member processes.)
+.IP \[bu]
+No domain controllers may be enabled in
+.IR x 's
+.I cgroup.subtree_control
+file.
+.P
+If any of the above constraints is violated, then an attempt to write
+.I \[dq]threaded\[dq]
+to a
+.I cgroup.type
+file fails with the error
+.BR ENOTSUP .
+.\"
+.SS The \[dq]domain threaded\[dq] cgroup type
+According to the pathways described above,
+the type of a cgroup can change to
+.I domain threaded
+in either of the following cases:
+.IP \[bu] 3
+The string
+.I \[dq]threaded\[dq]
+is written to a child cgroup.
+.IP \[bu]
+A threaded controller is enabled inside the cgroup and
+a process is made a member of the cgroup.
+.P
+A
+.I domain threaded
+cgroup,
+.IR x ,
+can revert to the type
+.I domain
+if the above conditions no longer hold true\[em]that is, if all
+.I threaded
+child cgroups of
+.I x
+are removed and either
+.I x
+no longer has threaded controllers enabled or
+no longer has member processes.
+.P
+When a
+.I domain threaded
+cgroup
+.I x
+reverts to the type
+.IR domain :
+.IP \[bu] 3
+All
+.I domain invalid
+descendants of
+.I x
+that are not in lower-level threaded subtrees revert to the type
+.IR domain .
+.IP \[bu]
+The root cgroups in any lower-level threaded subtrees revert to the type
+.IR "domain threaded" .
+.\"
+.SS Exceptions for the root cgroup
+The root cgroup of the v2 hierarchy is treated exceptionally:
+it can be the parent of both
+.I domain
+and
+.I threaded
+cgroups.
+If the string
+.I \[dq]threaded\[dq]
+is written to the
+.I cgroup.type
+file of one of the children of the root cgroup, then
+.IP \[bu] 3
+The type of that cgroup becomes
+.IR threaded .
+.IP \[bu]
+The type of any descendants of that cgroup that
+are not part of lower-level threaded subtrees changes to
+.IR "domain invalid" .
+.P
+Note that in this case, there is no cgroup whose type becomes
+.IR "domain threaded" .
+(Notionally, the root cgroup can be considered as the threaded root
+for the cgroup whose type was changed to
+.IR threaded .)
+.P
+The aim of this exceptional treatment for the root cgroup is to
+allow a threaded cgroup that employs the
+.I cpu
+controller to be placed as high as possible in the hierarchy,
+so as to minimize the (small) cost of traversing the cgroup hierarchy.
+.\"
+.SS The cgroups v2 \[dq]cpu\[dq] controller and realtime threads
+As at Linux 4.19, the cgroups v2
+.I cpu
+controller does not support control of realtime threads
+(specifically threads scheduled under any of the policies
+.BR SCHED_FIFO ,
+.BR SCHED_RR ,
+described
+.BR SCHED_DEADLINE ;
+see
+.BR sched (7)).
+Therefore, the
+.I cpu
+controller can be enabled in the root cgroup only
+if all realtime threads are in the root cgroup.
+(If there are realtime threads in nonroot cgroups, then a
+.BR write (2)
+of the string
+.I \[dq]+cpu\[dq]
+to the
+.I cgroup.subtree_control
+file fails with the error
+.BR EINVAL .)
+.P
+On some systems,
+.BR systemd (1)
+places certain realtime threads in nonroot cgroups in the v2 hierarchy.
+On such systems,
+these threads must first be moved to the root cgroup before the
+.I cpu
+controller can be enabled.
+.\"
+.SH ERRORS
+The following errors can occur for
+.BR mount (2):
+.TP
+.B EBUSY
+An attempt to mount a cgroup version 1 filesystem specified neither the
+.I name=
+option (to mount a named hierarchy) nor a controller name (or
+.IR all ).
+.SH NOTES
+A child process created via
+.BR fork (2)
+inherits its parent's cgroup memberships.
+A process's cgroup memberships are preserved across
+.BR execve (2).
+.P
+The
+.BR clone3 (2)
+.B CLONE_INTO_CGROUP
+flag can be used to create a child process that begins its life in
+a different version 2 cgroup from the parent process.
+.\"
+.SS /proc files
+.TP
+.IR /proc/cgroups " (since Linux 2.6.24)"
+This file contains information about the controllers
+that are compiled into the kernel.
+An example of the contents of this file (reformatted for readability)
+is the following:
+.IP
+.in +4n
+.EX
+#subsys_name    hierarchy      num_cgroups    enabled
+cpuset          4              1              1
+cpu             8              1              1
+cpuacct         8              1              1
+blkio           6              1              1
+memory          3              1              1
+devices         10             84             1
+freezer         7              1              1
+net_cls         9              1              1
+perf_event      5              1              1
+net_prio        9              1              1
+hugetlb         0              1              0
+pids            2              1              1
+.EE
+.in
+.IP
+The fields in this file are, from left to right:
+.RS
+.IP [1] 5
+The name of the controller.
+.IP [2]
+The unique ID of the cgroup hierarchy on which this controller is mounted.
+If multiple cgroups v1 controllers are bound to the same hierarchy,
+then each will show the same hierarchy ID in this field.
+The value in this field will be 0 if:
+.RS
+.IP \[bu] 3
+the controller is not mounted on a cgroups v1 hierarchy;
+.IP \[bu]
+the controller is bound to the cgroups v2 single unified hierarchy; or
+.IP \[bu]
+the controller is disabled (see below).
+.RE
+.IP [3]
+The number of control groups in this hierarchy using this controller.
+.IP [4]
+This field contains the value 1 if this controller is enabled,
+or 0 if it has been disabled (via the
+.I cgroup_disable
+kernel command-line boot parameter).
+.RE
+.TP
+.IR /proc/ pid /cgroup " (since Linux 2.6.24)"
+This file describes control groups to which the process
+with the corresponding PID belongs.
+The displayed information differs for
+cgroups version 1 and version 2 hierarchies.
+.IP
+For each cgroup hierarchy of which the process is a member,
+there is one entry containing three colon-separated fields:
+.IP
+.in +4n
+.EX
+hierarchy\-ID:controller\-list:cgroup\-path
+.EE
+.in
+.IP
+For example:
+.IP
+.in +4n
+.EX
+5:cpuacct,cpu,cpuset:/daemons
+.EE
+.in
+.IP
+The colon-separated fields are, from left to right:
+.RS
+.IP [1] 5
+For cgroups version 1 hierarchies,
+this field contains a unique hierarchy ID number
+that can be matched to a hierarchy ID in
+.IR /proc/cgroups .
+For the cgroups version 2 hierarchy, this field contains the value 0.
+.IP [2]
+For cgroups version 1 hierarchies,
+this field contains a comma-separated list of the controllers
+bound to the hierarchy.
+For the cgroups version 2 hierarchy, this field is empty.
+.IP [3]
+This field contains the pathname of the control group in the hierarchy
+to which the process belongs.
+This pathname is relative to the mount point of the hierarchy.
+.RE
+.\"
+.SS /sys/kernel/cgroup files
+.TP
+.IR /sys/kernel/cgroup/delegate " (since Linux 4.15)"
+.\" commit 01ee6cfb1483fe57c9cbd8e73817dfbf9bacffd3
+This file exports a list of the cgroups v2 files
+(one per line) that are delegatable
+(i.e., whose ownership should be changed to the user ID of the delegatee).
+In the future, the set of delegatable files may change or grow,
+and this file provides a way for the kernel to inform
+user-space applications of which files must be delegated.
+As at Linux 4.15, one sees the following when inspecting this file:
+.IP
+.in +4n
+.EX
+$ \fBcat /sys/kernel/cgroup/delegate\fP
+cgroup.procs
+cgroup.subtree_control
+cgroup.threads
+.EE
+.in
+.TP
+.IR /sys/kernel/cgroup/features " (since Linux 4.15)"
+.\" commit 5f2e673405b742be64e7c3604ed4ed3ac14f35ce
+Over time, the set of cgroups v2 features that are provided by the
+kernel may change or grow,
+or some features may not be enabled by default.
+This file provides a way for user-space applications to discover what
+features the running kernel supports and has enabled.
+Features are listed one per line:
+.IP
+.in +4n
+.EX
+$ \fBcat /sys/kernel/cgroup/features\fP
+nsdelegate
+memory_localevents
+.EE
+.in
+.IP
+The entries that can appear in this file are:
+.RS
+.TP
+.IR memory_localevents " (since Linux 5.2)"
+The kernel supports the
+.I memory_localevents
+mount option.
+.TP
+.IR nsdelegate " (since Linux 4.15)"
+The kernel supports the
+.I nsdelegate
+mount option.
+.TP
+.IR memory_recursiveprot " (since Linux 5.7)"
+.\" commit 8a931f801340c2be10552c7b5622d5f4852f3a36
+The kernel supports the
+.I memory_recursiveprot
+mount option.
+.RE
+.SH SEE ALSO
+.BR prlimit (1),
+.BR systemd (1),
+.BR systemd\-cgls (1),
+.BR systemd\-cgtop (1),
+.BR clone (2),
+.BR ioprio_set (2),
+.BR perf_event_open (2),
+.BR setrlimit (2),
+.BR cgroup_namespaces (7),
+.BR cpuset (7),
+.BR namespaces (7),
+.BR sched (7),
+.BR user_namespaces (7)
+.P
+The kernel source file
+.IR Documentation/admin\-guide/cgroup\-v2.rst .
diff --git a/man/man7/charsets.7 b/man/man7/charsets.7
new file mode 100644
index 000000000..8fa803b5f
--- /dev/null
+++ b/man/man7/charsets.7
@@ -0,0 +1,335 @@
+.\" Copyright (c) 1996 Eric S. Raymond <esr@thyrsus.com>
+.\" and Copyright (c) Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" This is combined from many sources, including notes by aeb and
+.\" research by esr.  Portions derive from a writeup by Roman Czyborra.
+.\"
+.\" Changes also by David Starner <dstarner98@aasaa.ofe.org>.
+.\"
+.TH charsets 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+charsets \- character set standards and internationalization
+.SH DESCRIPTION
+This manual page gives an overview on different character set standards
+and how they were used on Linux before Unicode became ubiquitous.
+Some of this information is still helpful for people working with legacy
+systems and documents.
+.P
+Standards discussed include such as
+ASCII, GB 2312, ISO/IEC\~8859, JIS, KOI8-R, KS, and Unicode.
+.P
+The primary emphasis is on character sets that were actually used by
+locale character sets, not the myriad others that could be found in data
+from other systems.
+.SS ASCII
+ASCII (American Standard Code For Information Interchange) is the original
+7-bit character set, originally designed for American English.
+Also known as US-ASCII.
+It is currently described by the ISO/IEC\~646:1991 IRV
+(International Reference Version) standard.
+.P
+Various ASCII variants replacing the dollar sign with other currency
+symbols and replacing punctuation with non-English alphabetic
+characters to cover German, French, Spanish, and others in 7 bits
+emerged.
+All are deprecated;
+glibc does not support locales whose character sets are not true
+supersets of ASCII.
+.P
+As Unicode, when using UTF-8, is ASCII-compatible, plain ASCII text
+still renders properly on modern UTF-8 using systems.
+.SS ISO/IEC\~8859
+ISO/IEC\~8859 is a series of 15 8-bit character sets, all of which have ASCII
+in their low (7-bit) half, invisible control characters in positions
+128 to 159, and 96 fixed-width graphics in positions 160\[en]255.
+.P
+Of these, the most important is ISO/IEC\~8859-1
+("Latin Alphabet No. 1" / Latin-1).
+It was widely adopted and supported by different systems,
+and is gradually being replaced with Unicode.
+The ISO/IEC\~8859-1 characters are also the first 256 characters of Unicode.
+.P
+Console support for the other ISO/IEC\~8859 character sets is available under
+Linux through user-mode utilities (such as
+.BR setfont (8))
+that modify keyboard bindings and the EGA graphics
+table and employ the "user mapping" font table in the console
+driver.
+.P
+Here are brief descriptions of each character set:
+.TP
+ISO/IEC\~8859-1 (Latin-1)
+Latin-1 covers many European languages such as Albanian, Basque,
+Danish, English, Faroese, Galician, Icelandic, Irish, Italian,
+Norwegian, Portuguese, Spanish, and Swedish.
+The lack of the ligatures
+Dutch IJ/ij,
+French œ,
+and „German“ quotation marks
+was considered tolerable.
+.TP
+ISO/IEC\~8859-2 (Latin-2)
+Latin-2 supports many Latin-written Central and East European
+languages such as Bosnian, Croatian, Czech, German, Hungarian, Polish,
+Slovak, and Slovene.
+Replacing Romanian ș/ț with ş/ţ
+was considered tolerable.
+.TP
+ISO/IEC\~8859-3 (Latin-3)
+Latin-3 was designed to cover of Esperanto, Maltese, and Turkish, but
+ISO/IEC\~8859-9 later superseded it for Turkish.
+.TP
+ISO/IEC\~8859-4 (Latin-4)
+Latin-4 introduced letters for North European languages such as
+Estonian, Latvian, and Lithuanian, but was superseded by ISO/IEC\~8859-10 and
+ISO/IEC\~8859-13.
+.TP
+ISO/IEC\~8859-5
+Cyrillic letters supporting Bulgarian, Byelorussian, Macedonian,
+Russian, Serbian, and (almost completely) Ukrainian.
+It was never widely used, see the discussion of KOI8-R/KOI8-U below.
+.TP
+ISO/IEC\~8859-6
+Was created for Arabic.
+The ISO/IEC\~8859-6 glyph table is a fixed font of separate
+letter forms, but a proper display engine should combine these
+using the proper initial, medial, and final forms.
+.TP
+ISO/IEC\~8859-7
+Was created for Modern Greek in 1987, updated in 2003.
+.TP
+ISO/IEC\~8859-8
+Supports Modern Hebrew without niqud (punctuation signs).
+Niqud and full-fledged Biblical Hebrew were outside the scope of this
+character set.
+.TP
+ISO/IEC\~8859-9 (Latin-5)
+This is a variant of Latin-1 that replaces Icelandic letters with
+Turkish ones.
+.TP
+ISO/IEC\~8859-10 (Latin-6)
+Latin-6 added the Inuit (Greenlandic) and Sami (Lappish) letters that were
+missing in Latin-4 to cover the entire Nordic area.
+.TP
+ISO/IEC\~8859-11
+Supports the Thai alphabet and is nearly identical to the TIS-620
+standard.
+.TP
+ISO/IEC\~8859-12
+This character set does not exist.
+.TP
+ISO/IEC\~8859-13 (Latin-7)
+Supports the Baltic Rim languages; in particular, it includes Latvian
+characters not found in Latin-4.
+.TP
+ISO/IEC\~8859-14 (Latin-8)
+This is the Celtic character set, covering Old Irish, Manx, Gaelic,
+Welsh, Cornish, and Breton.
+.TP
+ISO/IEC\~8859-15 (Latin-9)
+Latin-9 is similar to the widely used Latin-1 but replaces some less
+common symbols with the Euro sign and French and Finnish letters that
+were missing in Latin-1.
+.TP
+ISO/IEC\~8859-16 (Latin-10)
+This character set covers many Southeast European languages,
+and most importantly supports Romanian more completely than Latin-2.
+.SS KOI8-R / KOI8-U
+KOI8-R is a non-ISO character set popular in Russia before Unicode.
+The lower half is ASCII;
+the upper is a Cyrillic character set somewhat better designed than
+ISO/IEC\~8859-5.
+KOI8-U, based on KOI8-R, has better support for Ukrainian.
+Neither of these sets are ISO/IEC\~2022 compatible,
+unlike the ISO/IEC\~8859 series.
+.P
+Console support for KOI8-R is available under Linux through user-mode
+utilities that modify keyboard bindings and the EGA graphics table,
+and employ the "user mapping" font table in the console driver.
+.SS GB 2312
+GB 2312 is a mainland Chinese national standard character set used
+to express simplified Chinese.
+Just like JIS X 0208, characters are
+mapped into a 94x94 two-byte matrix used to construct EUC-CN.
+EUC-CN
+is the most important encoding for Linux and includes ASCII and
+GB 2312.
+Note that EUC-CN is often called as GB, GB 2312, or CN-GB.
+.SS Big5
+Big5 was a popular character set in Taiwan to express traditional
+Chinese.
+(Big5 is both a character set and an encoding.)
+It is a superset of ASCII.
+Non-ASCII characters are expressed in two bytes.
+Bytes 0xa1\[en]0xfe are used as leading bytes for two-byte characters.
+Big5 and its extension were widely used in Taiwan and Hong Kong.
+It is not ISO/IEC\~2022 compliant.
+.\" Thanks to Tomohiro KUBOTA for the following sections about
+.\" national standards.
+.SS JIS X 0208
+JIS X 0208 is a Japanese national standard character set.
+Though there are some more Japanese national standard character sets (like
+JIS X 0201, JIS X 0212, and JIS X 0213), this is the most important one.
+Characters are mapped into a 94x94 two-byte matrix,
+whose each byte is in the range 0x21\[en]0x7e.
+Note that JIS X 0208 is a character set, not an encoding.
+This means that JIS X 0208
+itself is not used for expressing text data.
+JIS X 0208 is used
+as a component to construct encodings such as EUC-JP, Shift_JIS,
+and ISO/IEC\~2022-JP.
+EUC-JP is the most important encoding for Linux
+and includes ASCII and JIS X 0208.
+In EUC-JP, JIS X 0208
+characters are expressed in two bytes, each of which is the
+JIS X 0208 code plus 0x80.
+.SS KS X 1001
+KS X 1001 is a Korean national standard character set.
+Just as
+JIS X 0208, characters are mapped into a 94x94 two-byte matrix.
+KS X 1001 is used like JIS X 0208, as a component
+to construct encodings such as EUC-KR, Johab, and ISO/IEC\~2022-KR.
+EUC-KR is the most important encoding for Linux and includes
+ASCII and KS X 1001.
+KS C 5601 is an older name for KS X 1001.
+.SS ISO/IEC\~2022 and ISO/IEC\~4873
+The ISO/IEC\~2022 and ISO/IEC\~4873 standards describe a font-control model
+based on VT100 practice.
+This model is (partially) supported
+by the Linux kernel and by
+.BR xterm (1).
+Several ISO/IEC\~2022-based character encodings have been defined,
+especially for Japanese.
+.P
+There are 4 graphic character sets, called G0, G1, G2, and G3,
+and one of them is the current character set for codes with
+high bit zero (initially G0), and one of them is the current
+character set for codes with high bit one (initially G1).
+Each graphic character set has 94 or 96 characters, and is
+essentially a 7-bit character set.
+It uses codes either
+040\[en]0177 (041\[en]0176) or 0240\[en]0377 (0241\[en]0376).
+G0 always has size 94 and uses codes 041\[en]0176.
+.P
+Switching between character sets is done using the shift functions
+\fB\[ha]N\fP (SO or LS1), \fB\[ha]O\fP (SI or LS0), ESC n (LS2), ESC o (LS3),
+ESC N (SS2), ESC O (SS3), ESC \[ti] (LS1R), ESC } (LS2R), ESC | (LS3R).
+The function LS\fIn\fP makes character set G\fIn\fP the current one
+for codes with high bit zero.
+The function LS\fIn\fPR makes character set G\fIn\fP the current one
+for codes with high bit one.
+The function SS\fIn\fP makes character set G\fIn\fP (\fIn\fP=2 or 3)
+the current one for the next character only (regardless of the value
+of its high order bit).
+.P
+A 94-character set is designated as G\fIn\fP character set
+by an escape sequence ESC ( xx (for G0), ESC ) xx (for G1),
+ESC * xx (for G2), ESC + xx (for G3), where xx is a symbol
+or a pair of symbols found in the ISO/IEC\~2375 International
+Register of Coded Character Sets.
+For example, ESC ( @ selects the ISO/IEC\~646 character set as G0,
+ESC ( A selects the UK standard character set (with pound
+instead of number sign), ESC ( B selects ASCII (with dollar
+instead of currency sign), ESC ( M selects a character set
+for African languages, ESC ( ! A selects the Cuban character
+set, and so on.
+.P
+A 96-character set is designated as G\fIn\fP character set
+by an escape sequence ESC \- xx (for G1), ESC . xx (for G2)
+or ESC / xx (for G3).
+For example, ESC \- G selects the Hebrew alphabet as G1.
+.P
+A multibyte character set is designated as G\fIn\fP character set
+by an escape sequence ESC $ xx or ESC $ ( xx (for G0),
+ESC $ ) xx (for G1), ESC $ * xx (for G2), ESC $ + xx (for G3).
+For example, ESC $ ( C selects the Korean character set for G0.
+The Japanese character set selected by ESC $ B has a more
+recent version selected by ESC & @ ESC $ B.
+.P
+ISO/IEC\~4873 stipulates a narrower use of character sets, where G0
+is fixed (always ASCII), so that G1, G2, and G3
+can be invoked only for codes with the high order bit set.
+In particular, \fB\[ha]N\fP and \fB\[ha]O\fP are not used anymore, ESC ( xx
+can be used only with xx=B, and ESC ) xx, ESC * xx, ESC + xx
+are equivalent to ESC \- xx, ESC . xx, ESC / xx, respectively.
+.SS TIS-620
+TIS-620 is a Thai national standard character set and a superset
+of ASCII.
+In the same fashion as the ISO/IEC\~8859 series, Thai characters are mapped into
+0xa1\[en]0xfe.
+.SS Unicode
+Unicode (ISO/IEC 10646) is a standard which aims to unambiguously represent
+every character in every human language.
+Unicode's structure permits 20.1 bits to encode every character.
+Since most computers don't include 20.1-bit integers, Unicode is
+usually encoded as 32-bit integers internally and either a series of
+16-bit integers (UTF-16) (needing two 16-bit integers only when
+encoding certain rare characters) or a series of 8-bit bytes (UTF-8).
+.P
+Linux represents Unicode using the 8-bit Unicode Transformation Format
+(UTF-8).
+UTF-8 is a variable length encoding of Unicode.
+It uses 1
+byte to code 7 bits, 2 bytes for 11 bits, 3 bytes for 16 bits, 4 bytes
+for 21 bits, 5 bytes for 26 bits, 6 bytes for 31 bits.
+.P
+Let 0,1,x stand for a zero, one, or arbitrary bit.
+A byte 0xxxxxxx
+stands for the Unicode 00000000 0xxxxxxx which codes the same symbol
+as the ASCII 0xxxxxxx.
+Thus, ASCII goes unchanged into UTF-8, and
+people using only ASCII do not notice any change: not in code, and not
+in file size.
+.P
+A byte 110xxxxx is the start of a 2-byte code, and 110xxxxx 10yyyyyy
+is assembled into 00000xxx xxyyyyyy.
+A byte 1110xxxx is the start
+of a 3-byte code, and 1110xxxx 10yyyyyy 10zzzzzz is assembled
+into xxxxyyyy yyzzzzzz.
+(When UTF-8 is used to code the 31-bit ISO/IEC 10646
+then this progression continues up to 6-byte codes.)
+.P
+For most texts in ISO/IEC\~8859 character sets, this means that the
+characters outside of ASCII are now coded with two bytes.
+This tends
+to expand ordinary text files by only one or two percent.
+For Russian
+or Greek texts, this expands ordinary text files by 100%, since text in
+those languages is mostly outside of ASCII.
+For Japanese users this means
+that the 16-bit codes now in common use will take three bytes.
+While there are algorithmic conversions from some character sets
+(especially ISO/IEC\~8859-1) to Unicode, general conversion requires
+carrying around conversion tables, which can be quite large for 16-bit
+codes.
+.P
+Note that UTF-8 is self-synchronizing:
+10xxxxxx is a tail,
+any other byte is the head of a code.
+Note that the only way ASCII bytes occur in a UTF-8 stream,
+is as themselves.
+In particular,
+there are no embedded NULs (\[aq]\e0\[aq]) or \[aq]/\[aq]s
+that form part of some larger code.
+.P
+Since ASCII, and, in particular, NUL and \[aq]/\[aq], are unchanged, the
+kernel does not notice that UTF-8 is being used.
+It does not care at
+all what the bytes it is handling stand for.
+.P
+Rendering of Unicode data streams is typically handled through
+"subfont" tables which map a subset of Unicode to glyphs.
+Internally
+the kernel uses Unicode to describe the subfont loaded in video RAM.
+This means that in the Linux console in UTF-8 mode, one can use a character
+set with 512 different symbols.
+This is not enough for Japanese, Chinese, and
+Korean, but it is enough for most other purposes.
+.SH SEE ALSO
+.BR iconv (1),
+.BR ascii (7),
+.BR iso_8859\-1 (7),
+.BR unicode (7),
+.BR utf\-8 (7)
diff --git a/man/man7/complex.7 b/man/man7/complex.7
new file mode 100644
index 000000000..fa8cb2631
--- /dev/null
+++ b/man/man7/complex.7
@@ -0,0 +1,83 @@
+.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.TH complex 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+complex \- basics of complex mathematics
+.SH LIBRARY
+Math library
+.RI ( libm ", " \-lm )
+.SH SYNOPSIS
+.nf
+.B #include <complex.h>
+.fi
+.SH DESCRIPTION
+Complex numbers are numbers of the form z = a+b*i, where a and b are
+real numbers and i = sqrt(\-1), so that i*i = \-1.
+.P
+There are other ways to represent that number.
+The pair (a,b) of real
+numbers may be viewed as a point in the plane, given by X- and
+Y-coordinates.
+This same point may also be described by giving
+the pair of real numbers (r,phi), where r is the distance to the origin O,
+and phi the angle between the X-axis and the line Oz.
+Now
+z = r*exp(i*phi) = r*(cos(phi)+i*sin(phi)).
+.P
+The basic operations are defined on z = a+b*i and w = c+d*i as:
+.TP
+.B addition: z+w = (a+c) + (b+d)*i
+.TP
+.B multiplication: z*w = (a*c \- b*d) + (a*d + b*c)*i
+.TP
+.B division: z/w = ((a*c + b*d)/(c*c + d*d)) + ((b*c \- a*d)/(c*c + d*d))*i
+.P
+Nearly all math function have a complex counterpart but there are
+some complex-only functions.
+.SH EXAMPLES
+Your C-compiler can work with complex numbers if it supports the C99 standard.
+The imaginary unit is represented by I.
+.P
+.EX
+/* check that exp(i * pi) == \-1 */
+#include <math.h>        /* for atan */
+#include <stdio.h>
+#include <complex.h>
+\&
+int
+main(void)
+{
+    double pi = 4 * atan(1.0);
+    double complex z = cexp(I * pi);
+    printf("%f + %f * i\en", creal(z), cimag(z));
+}
+.EE
+.SH SEE ALSO
+.BR cabs (3),
+.BR cacos (3),
+.BR cacosh (3),
+.BR carg (3),
+.BR casin (3),
+.BR casinh (3),
+.BR catan (3),
+.BR catanh (3),
+.BR ccos (3),
+.BR ccosh (3),
+.BR cerf (3),
+.BR cexp (3),
+.BR cexp2 (3),
+.BR cimag (3),
+.BR clog (3),
+.BR clog10 (3),
+.BR clog2 (3),
+.BR conj (3),
+.BR cpow (3),
+.BR cproj (3),
+.BR creal (3),
+.BR csin (3),
+.BR csinh (3),
+.BR csqrt (3),
+.BR ctan (3),
+.BR ctanh (3)
diff --git a/man/man7/cp1251.7 b/man/man7/cp1251.7
new file mode 100644
index 000000000..0fbc568a2
--- /dev/null
+++ b/man/man7/cp1251.7
@@ -0,0 +1,166 @@
+'\" t
+.\" Copyright 2009    Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH cp1251 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cp1251 \- CP\ 1251 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The Windows Code Pages include several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+CP\ 1251 encodes the
+characters used in Cyrillic scripts.
+.SS CP\ 1251 characters
+The following table displays the characters in CP\ 1251 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+200	128	80	Ђ	CYRILLIC CAPITAL LETTER DJE
+201	129	81	Ѓ	CYRILLIC CAPITAL LETTER GJE
+202	130	82	‚	SINGLE LOW-9 QUOTATION MARK
+203	131	83	ѓ	CYRILLIC SMALL LETTER GJE
+204	132	84	„	DOUBLE LOW-9 QUOTATION MARK
+205	133	85	…	HORIZONTAL ELLIPSIS
+206	134	86	†	DAGGER
+207	135	87	‡	DOUBLE DAGGER
+210	136	88	€	EURO SIGN
+211	137	89	‰	PER MILLE SIGN
+212	138	8A	Љ	CYRILLIC CAPITAL LETTER LJE
+213	139	8B	‹	SINGLE LEFT-POINTING ANGLE QUOTATION MARK
+214	140	8C	Њ	CYRILLIC CAPITAL LETTER NJE
+215	141	8D	Ќ	CYRILLIC CAPITAL LETTER KJE
+216	142	8E	Ћ	CYRILLIC CAPITAL LETTER TSHE
+217	143	8F	Џ	CYRILLIC CAPITAL LETTER DZHE
+220	144	90	ђ	CYRILLIC SMALL LETTER DJE
+221	145	91	‘	LEFT SINGLE QUOTATION MARK
+222	146	92	’	RIGHT SINGLE QUOTATION MARK
+223	147	93	“	LEFT DOUBLE QUOTATION MARK
+224	148	94	”	RIGHT DOUBLE QUOTATION MARK
+225	149	95	•	BULLET
+226	150	96	–	EN DASH
+227	151	97	—	EM DASH
+230	152	98	 	UNDEFINED
+231	153	99	™	TRADE MARK SIGN
+232	154	9A	љ	CYRILLIC SMALL LETTER LJE
+233	155	9B	›	SINGLE RIGHT-POINTING ANGLE QUOTATION MARK
+234	156	9C	њ	CYRILLIC SMALL LETTER NJE
+235	157	9D	ќ	CYRILLIC SMALL LETTER KJE
+236	158	9E	ћ	CYRILLIC SMALL LETTER TSHE
+237	159	9F	џ	CYRILLIC SMALL LETTER DZHE
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ў	CYRILLIC CAPITAL LETTER SHORT U
+242	162	A2	ў	CYRILLIC SMALL LETTER SHORT U
+243	163	A3	Ј	CYRILLIC CAPITAL LETTER JE
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	Ґ	CYRILLIC CAPITAL LETTER GHE WITH UPTURN
+246	166	A6	¦	BROKEN BAR
+247	167	A7	§	SECTION SIGN
+250	168	A8	Ё	CYRILLIC CAPITAL LETTER IO
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	Є	CYRILLIC CAPITAL LETTER UKRAINIAN IE
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	Ї	CYRILLIC CAPITAL LETTER YI
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	І	T{
+CYRILLIC CAPITAL LETTER
+.br
+BYELORUSSIAN-UKRAINIAN I
+T}
+263	179	B3	і	CYRILLIC SMALL LETTER BYELORUSSIAN-UKRAINIAN I
+264	180	B4	ґ	CYRILLIC SMALL LETTER GHE WITH UPTURN
+265	181	B5	µ	MICRO SIGN
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	ё	CYRILLIC SMALL LETTER IO
+271	185	B9	№	NUMERO SIGN
+272	186	BA	є	CYRILLIC SMALL LETTER UKRAINIAN IE
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	ј	CYRILLIC SMALL LETTER JE
+275	189	BD	Ѕ	CYRILLIC CAPITAL LETTER DZE
+276	190	BE	ѕ	CYRILLIC SMALL LETTER DZE
+277	191	BF	ї	CYRILLIC SMALL LETTER YI
+300	192	C0	А	CYRILLIC CAPITAL LETTER A
+301	193	C1	Б	CYRILLIC CAPITAL LETTER BE
+302	194	C2	В	CYRILLIC CAPITAL LETTER VE
+303	195	C3	Г	CYRILLIC CAPITAL LETTER GHE
+304	196	C4	Д	CYRILLIC CAPITAL LETTER DE
+305	197	C5	Е	CYRILLIC CAPITAL LETTER IE
+306	198	C6	Ж	CYRILLIC CAPITAL LETTER ZHE
+307	199	C7	З	CYRILLIC CAPITAL LETTER ZE
+310	200	C8	И	CYRILLIC CAPITAL LETTER I
+311	201	C9	Й	CYRILLIC CAPITAL LETTER SHORT I
+312	202	CA	К	CYRILLIC CAPITAL LETTER KA
+313	203	CB	Л	CYRILLIC CAPITAL LETTER EL
+314	204	CC	М	CYRILLIC CAPITAL LETTER EM
+315	205	CD	Н	CYRILLIC CAPITAL LETTER EN
+316	206	CE	О	CYRILLIC CAPITAL LETTER O
+317	207	CF	П	CYRILLIC CAPITAL LETTER PE
+320	208	D0	Р	CYRILLIC CAPITAL LETTER ER
+321	209	D1	С	CYRILLIC CAPITAL LETTER ES
+322	210	D2	Т	CYRILLIC CAPITAL LETTER TE
+323	211	D3	У	CYRILLIC CAPITAL LETTER U
+324	212	D4	Ф	CYRILLIC CAPITAL LETTER EF
+325	213	D5	Х	CYRILLIC CAPITAL LETTER HA
+326	214	D6	Ц	CYRILLIC CAPITAL LETTER TSE
+327	215	D7	Ч	CYRILLIC CAPITAL LETTER CHE
+330	216	D8	Ш	CYRILLIC CAPITAL LETTER SHA
+331	217	D9	Щ	CYRILLIC CAPITAL LETTER SHCHA
+332	218	DA	Ъ	CYRILLIC CAPITAL LETTER HARD SIGN
+333	219	DB	Ы	CYRILLIC CAPITAL LETTER YERU
+334	220	DC	Ь	CYRILLIC CAPITAL LETTER SOFT SIGN
+335	221	DD	Э	CYRILLIC CAPITAL LETTER E
+336	222	DE	Ю	CYRILLIC CAPITAL LETTER YU
+337	223	DF	Я	CYRILLIC CAPITAL LETTER YA
+340	224	E0	а	CYRILLIC SMALL LETTER A
+341	225	E1	б	CYRILLIC SMALL LETTER BE
+342	226	E2	в	CYRILLIC SMALL LETTER VE
+343	227	E3	г	CYRILLIC SMALL LETTER GHE
+344	228	E4	д	CYRILLIC SMALL LETTER DE
+345	229	E5	е	CYRILLIC SMALL LETTER IE
+346	230	E6	ж	CYRILLIC SMALL LETTER ZHE
+347	231	E7	з	CYRILLIC SMALL LETTER ZE
+350	232	E8	и	CYRILLIC SMALL LETTER I
+351	233	E9	й	CYRILLIC SMALL LETTER SHORT I
+352	234	EA	к	CYRILLIC SMALL LETTER KA
+353	235	EB	л	CYRILLIC SMALL LETTER EL
+354	236	EC	м	CYRILLIC SMALL LETTER EM
+355	237	ED	н	CYRILLIC SMALL LETTER EN
+356	238	EE	о	CYRILLIC SMALL LETTER O
+357	239	EF	п	CYRILLIC SMALL LETTER PE
+360	240	F0	р	CYRILLIC SMALL LETTER ER
+361	241	F1	с	CYRILLIC SMALL LETTER ES
+362	242	F2	т	CYRILLIC SMALL LETTER TE
+363	243	F3	у	CYRILLIC SMALL LETTER U
+364	244	F4	ф	CYRILLIC SMALL LETTER EF
+365	245	F5	х	CYRILLIC SMALL LETTER HA
+366	246	F6	ц	CYRILLIC SMALL LETTER TSE
+367	247	F7	ч	CYRILLIC SMALL LETTER CHE
+370	248	F8	ш	CYRILLIC SMALL LETTER SHA
+371	249	F9	щ	CYRILLIC SMALL LETTER SHCHA
+372	250	FA	ъ	CYRILLIC SMALL LETTER HARD SIGN
+373	251	FB	ы	CYRILLIC SMALL LETTER YERU
+374	252	FC	ь	CYRILLIC SMALL LETTER SOFT SIGN
+375	253	FD	э	CYRILLIC SMALL LETTER E
+376	254	FE	ю	CYRILLIC SMALL LETTER YU
+377	255	FF	я	CYRILLIC SMALL LETTER YA
+.TE
+.SH NOTES
+CP\ 1251 is also known as Windows Cyrillic.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR cp1252 (7),
+.BR iso_8859\-5 (7),
+.BR koi8\-r (7),
+.BR koi8\-u (7),
+.BR utf\-8 (7)
diff --git a/man/man7/cp1252.7 b/man/man7/cp1252.7
new file mode 100644
index 000000000..22499383e
--- /dev/null
+++ b/man/man7/cp1252.7
@@ -0,0 +1,156 @@
+'\" t
+.\" Copyright 2014 (C) Marko Myllynen <myllynen@redhat.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH cp1252 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cp1252 \- CP\ 1252 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The Windows Code Pages include several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+CP\ 1252 encodes the
+characters used in many West European languages.
+.SS CP\ 1252 characters
+The following table displays the characters in CP\ 1252 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+200	128	80	€	EURO SIGN
+202	130	82	‚	SINGLE LOW-9 QUOTATION MARK
+203	131	83	ƒ	LATIN SMALL LETTER F WITH HOOK
+204	132	84	„	DOUBLE LOW-9 QUOTATION MARK
+205	133	85	…	HORIZONTAL ELLIPSIS
+206	134	86	†	DAGGER
+207	135	87	‡	DOUBLE DAGGER
+210	136	88	ˆ	MODIFIER LETTER CIRCUMFLEX ACCENT
+211	137	89	‰	PER MILLE SIGN
+212	138	8A	Š	LATIN CAPITAL LETTER S WITH CARON
+213	139	8B	‹	SINGLE LEFT-POINTING ANGLE QUOTATION MARK
+214	140	8C	Œ	LATIN CAPITAL LIGATURE OE
+216	142	8E	Ž	LATIN CAPITAL LETTER Z WITH CARON
+221	145	91	‘	LEFT SINGLE QUOTATION MARK
+222	146	92	’	RIGHT SINGLE QUOTATION MARK
+223	147	93	“	LEFT DOUBLE QUOTATION MARK
+224	148	94	”	RIGHT DOUBLE QUOTATION MARK
+225	149	95	•	BULLET
+226	150	96	–	EN DASH
+227	151	97	—	EM DASH
+230	152	98	˜	SMALL TILDE
+231	153	99	™	TRADE MARK SIGN
+232	154	9A	š	LATIN SMALL LETTER S WITH CARON
+233	155	9B	›	SINGLE RIGHT-POINTING ANGLE QUOTATION MARK
+234	156	9C	œ	LATIN SMALL LIGATURE OE
+236	158	9E	ž	LATIN SMALL LETTER Z WITH CARON
+237	159	9F	Ÿ	LATIN CAPITAL LETTER Y WITH DIAERESIS
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	¡	INVERTED EXCLAMATION MARK
+242	162	A2	¢	CENT SIGN
+243	163	A3	£	POUND SIGN
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	¥	YEN SIGN
+246	166	A6	¦	BROKEN BAR
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	ª	FEMININE ORDINAL INDICATOR
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	¯	MACRON
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	´	ACUTE ACCENT
+265	181	B5	µ	MICRO SIGN
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	¸	CEDILLA
+271	185	B9	¹	SUPERSCRIPT ONE
+272	186	BA	º	MASCULINE ORDINAL INDICATOR
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	¼	VULGAR FRACTION ONE QUARTER
+275	189	BD	½	VULGAR FRACTION ONE HALF
+276	190	BE	¾	VULGAR FRACTION THREE QUARTERS
+277	191	BF	¿	INVERTED QUESTION MARK
+300	192	C0	À	LATIN CAPITAL LETTER A WITH GRAVE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ã	LATIN CAPITAL LETTER A WITH TILDE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	È	LATIN CAPITAL LETTER E WITH GRAVE
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ê	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ì	LATIN CAPITAL LETTER I WITH GRAVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+320	208	D0	Ð	LATIN CAPITAL LETTER ETH
+321	209	D1	Ñ	LATIN CAPITAL LETTER N WITH TILDE
+322	210	D2	Ò	LATIN CAPITAL LETTER O WITH GRAVE
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+331	217	D9	Ù	LATIN CAPITAL LETTER U WITH GRAVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ý	LATIN CAPITAL LETTER Y WITH ACUTE
+336	222	DE	Þ	LATIN CAPITAL LETTER THORN
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	à	LATIN SMALL LETTER A WITH GRAVE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ã	LATIN SMALL LETTER A WITH TILDE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	è	LATIN SMALL LETTER E WITH GRAVE
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ê	LATIN SMALL LETTER E WITH CIRCUMFLEX
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ì	LATIN SMALL LETTER I WITH GRAVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+360	240	F0	ð	LATIN SMALL LETTER ETH
+361	241	F1	ñ	LATIN SMALL LETTER N WITH TILDE
+362	242	F2	ò	LATIN SMALL LETTER O WITH GRAVE
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ø	LATIN SMALL LETTER O WITH STROKE
+371	249	F9	ù	LATIN SMALL LETTER U WITH GRAVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ý	LATIN SMALL LETTER Y WITH ACUTE
+376	254	FE	þ	LATIN SMALL LETTER THORN
+377	255	FF	ÿ	LATIN SMALL LETTER Y WITH DIAERESIS
+.TE
+.SH NOTES
+CP\ 1252 is also known as Windows-1252.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR cp1251 (7),
+.BR iso_8859\-1 (7),
+.BR iso_8859\-15 (7),
+.BR utf\-8 (7)
diff --git a/man/man7/cpuset.7 b/man/man7/cpuset.7
new file mode 100644
index 000000000..7ae130ebb
--- /dev/null
+++ b/man/man7/cpuset.7
@@ -0,0 +1,1504 @@
+.\" Copyright (c) 2008 Silicon Graphics, Inc.
+.\"
+.\" Author: Paul Jackson (http://oss.sgi.com/projects/cpusets)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-only
+.\"
+.TH cpuset 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+cpuset \- confine processes to processor and memory node subsets
+.SH DESCRIPTION
+The cpuset filesystem is a pseudo-filesystem interface
+to the kernel cpuset mechanism,
+which is used to control the processor placement
+and memory placement of processes.
+It is commonly mounted at
+.IR /dev/cpuset .
+.P
+On systems with kernels compiled with built in support for cpusets,
+all processes are attached to a cpuset, and cpusets are always present.
+If a system supports cpusets, then it will have the entry
+.B nodev cpuset
+in the file
+.IR /proc/filesystems .
+By mounting the cpuset filesystem (see the
+.B EXAMPLES
+section below),
+the administrator can configure the cpusets on a system
+to control the processor and memory placement of processes
+on that system.
+By default, if the cpuset configuration
+on a system is not modified or if the cpuset filesystem
+is not even mounted, then the cpuset mechanism,
+though present, has no effect on the system's behavior.
+.P
+A cpuset defines a list of CPUs and memory nodes.
+.P
+The CPUs of a system include all the logical processing
+units on which a process can execute, including, if present,
+multiple processor cores within a package and Hyper-Threads
+within a processor core.
+Memory nodes include all distinct
+banks of main memory; small and SMP systems typically have
+just one memory node that contains all the system's main memory,
+while NUMA (non-uniform memory access) systems have multiple memory nodes.
+.P
+Cpusets are represented as directories in a hierarchical
+pseudo-filesystem, where the top directory in the hierarchy
+.RI ( /dev/cpuset )
+represents the entire system (all online CPUs and memory nodes)
+and any cpuset that is the child (descendant) of
+another parent cpuset contains a subset of that parent's
+CPUs and memory nodes.
+The directories and files representing cpusets have normal
+filesystem permissions.
+.P
+Every process in the system belongs to exactly one cpuset.
+A process is confined to run only on the CPUs in
+the cpuset it belongs to, and to allocate memory only
+on the memory nodes in that cpuset.
+When a process
+.BR fork (2)s,
+the child process is placed in the same cpuset as its parent.
+With sufficient privilege, a process may be moved from one
+cpuset to another and the allowed CPUs and memory nodes
+of an existing cpuset may be changed.
+.P
+When the system begins booting, a single cpuset is
+defined that includes all CPUs and memory nodes on the
+system, and all processes are in that cpuset.
+During the boot process, or later during normal system operation,
+other cpusets may be created, as subdirectories of this top cpuset,
+under the control of the system administrator,
+and processes may be placed in these other cpusets.
+.P
+Cpusets are integrated with the
+.BR sched_setaffinity (2)
+scheduling affinity mechanism and the
+.BR mbind (2)
+and
+.BR set_mempolicy (2)
+memory-placement mechanisms in the kernel.
+Neither of these mechanisms let a process make use
+of a CPU or memory node that is not allowed by that process's cpuset.
+If changes to a process's cpuset placement conflict with these
+other mechanisms, then cpuset placement is enforced
+even if it means overriding these other mechanisms.
+The kernel accomplishes this overriding by silently
+restricting the CPUs and memory nodes requested by
+these other mechanisms to those allowed by the
+invoking process's cpuset.
+This can result in these
+other calls returning an error, if for example, such
+a call ends up requesting an empty set of CPUs or
+memory nodes, after that request is restricted to
+the invoking process's cpuset.
+.P
+Typically, a cpuset is used to manage
+the CPU and memory-node confinement for a set of
+cooperating processes such as a batch scheduler job, and these
+other mechanisms are used to manage the placement of
+individual processes or memory regions within that set or job.
+.SH FILES
+Each directory below
+.I /dev/cpuset
+represents a cpuset and contains a fixed set of pseudo-files
+describing the state of that cpuset.
+.P
+New cpusets are created using the
+.BR mkdir (2)
+system call or the
+.BR mkdir (1)
+command.
+The properties of a cpuset, such as its flags, allowed
+CPUs and memory nodes, and attached processes, are queried and modified
+by reading or writing to the appropriate file in that cpuset's directory,
+as listed below.
+.P
+The pseudo-files in each cpuset directory are automatically created when
+the cpuset is created, as a result of the
+.BR mkdir (2)
+invocation.
+It is not possible to directly add or remove these pseudo-files.
+.P
+A cpuset directory that contains no child cpuset directories,
+and has no attached processes, can be removed using
+.BR rmdir (2)
+or
+.BR rmdir (1).
+It is not necessary, or possible,
+to remove the pseudo-files inside the directory before removing it.
+.P
+The pseudo-files in each cpuset directory are
+small text files that may be read and
+written using traditional shell utilities such as
+.BR cat (1),
+and
+.BR echo (1),
+or from a program by using file I/O library functions or system calls,
+such as
+.BR open (2),
+.BR read (2),
+.BR write (2),
+and
+.BR close (2).
+.P
+The pseudo-files in a cpuset directory represent internal kernel
+state and do not have any persistent image on disk.
+Each of these per-cpuset files is listed and described below.
+.\" ====================== tasks ======================
+.TP
+.I tasks
+List of the process IDs (PIDs) of the processes in that cpuset.
+The list is formatted as a series of ASCII
+decimal numbers, each followed by a newline.
+A process may be added to a cpuset (automatically removing
+it from the cpuset that previously contained it) by writing its
+PID to that cpuset's
+.I tasks
+file (with or without a trailing newline).
+.IP
+.B Warning:
+only one PID may be written to the
+.I tasks
+file at a time.
+If a string is written that contains more
+than one PID, only the first one will be used.
+.\" =================== notify_on_release ===================
+.TP
+.I notify_on_release
+Flag (0 or 1).
+If set (1), that cpuset will receive special handling
+after it is released, that is, after all processes cease using
+it (i.e., terminate or are moved to a different cpuset)
+and all child cpuset directories have been removed.
+See the \fBNotify On Release\fR section, below.
+.\" ====================== cpus ======================
+.TP
+.I cpuset.cpus
+List of the physical numbers of the CPUs on which processes
+in that cpuset are allowed to execute.
+See \fBList Format\fR below for a description of the
+format of
+.IR cpus .
+.IP
+The CPUs allowed to a cpuset may be changed by
+writing a new list to its
+.I cpus
+file.
+.\" ==================== cpu_exclusive ====================
+.TP
+.I cpuset.cpu_exclusive
+Flag (0 or 1).
+If set (1), the cpuset has exclusive use of
+its CPUs (no sibling or cousin cpuset may overlap CPUs).
+By default, this is off (0).
+Newly created cpusets also initially default this to off (0).
+.IP
+Two cpusets are
+.I sibling
+cpusets if they share the same parent cpuset in the
+.I /dev/cpuset
+hierarchy.
+Two cpusets are
+.I cousin
+cpusets if neither is the ancestor of the other.
+Regardless of the
+.I cpu_exclusive
+setting, if one cpuset is the ancestor of another,
+and if both of these cpusets have nonempty
+.IR cpus ,
+then their
+.I cpus
+must overlap, because the
+.I cpus
+of any cpuset are always a subset of the
+.I cpus
+of its parent cpuset.
+.\" ====================== mems ======================
+.TP
+.I cpuset.mems
+List of memory nodes on which processes in this cpuset are
+allowed to allocate memory.
+See \fBList Format\fR below for a description of the
+format of
+.IR mems .
+.\" ==================== mem_exclusive ====================
+.TP
+.I cpuset.mem_exclusive
+Flag (0 or 1).
+If set (1), the cpuset has exclusive use of
+its memory nodes (no sibling or cousin may overlap).
+Also if set (1), the cpuset is a \fBHardwall\fR cpuset (see below).
+By default, this is off (0).
+Newly created cpusets also initially default this to off (0).
+.IP
+Regardless of the
+.I mem_exclusive
+setting, if one cpuset is the ancestor of another,
+then their memory nodes must overlap, because the memory
+nodes of any cpuset are always a subset of the memory nodes
+of that cpuset's parent cpuset.
+.\" ==================== mem_hardwall ====================
+.TP
+.IR cpuset.mem_hardwall " (since Linux 2.6.26)"
+Flag (0 or 1).
+If set (1), the cpuset is a \fBHardwall\fR cpuset (see below).
+Unlike \fBmem_exclusive\fR,
+there is no constraint on whether cpusets
+marked \fBmem_hardwall\fR may have overlapping
+memory nodes with sibling or cousin cpusets.
+By default, this is off (0).
+Newly created cpusets also initially default this to off (0).
+.\" ==================== memory_migrate ====================
+.TP
+.IR cpuset.memory_migrate " (since Linux 2.6.16)"
+Flag (0 or 1).
+If set (1), then memory migration is enabled.
+By default, this is off (0).
+See the \fBMemory Migration\fR section, below.
+.\" ==================== memory_pressure ====================
+.TP
+.IR cpuset.memory_pressure " (since Linux 2.6.16)"
+A measure of how much memory pressure the processes in this
+cpuset are causing.
+See the \fBMemory Pressure\fR section, below.
+Unless
+.I memory_pressure_enabled
+is enabled, always has value zero (0).
+This file is read-only.
+See the
+.B WARNINGS
+section, below.
+.\" ================= memory_pressure_enabled =================
+.TP
+.IR cpuset.memory_pressure_enabled " (since Linux 2.6.16)"
+Flag (0 or 1).
+This file is present only in the root cpuset, normally
+.IR /dev/cpuset .
+If set (1), the
+.I memory_pressure
+calculations are enabled for all cpusets in the system.
+By default, this is off (0).
+See the
+\fBMemory Pressure\fR section, below.
+.\" ================== memory_spread_page ==================
+.TP
+.IR cpuset.memory_spread_page " (since Linux 2.6.17)"
+Flag (0 or 1).
+If set (1), pages in the kernel page cache
+(filesystem buffers) are uniformly spread across the cpuset.
+By default, this is off (0) in the top cpuset,
+and inherited from the parent cpuset in
+newly created cpusets.
+See the \fBMemory Spread\fR section, below.
+.\" ================== memory_spread_slab ==================
+.TP
+.IR cpuset.memory_spread_slab " (since Linux 2.6.17)"
+Flag (0 or 1).
+If set (1), the kernel slab caches
+for file I/O (directory and inode structures) are
+uniformly spread across the cpuset.
+By default, is off (0) in the top cpuset,
+and inherited from the parent cpuset in
+newly created cpusets.
+See the \fBMemory Spread\fR section, below.
+.\" ================== sched_load_balance ==================
+.TP
+.IR cpuset.sched_load_balance " (since Linux 2.6.24)"
+Flag (0 or 1).
+If set (1, the default) the kernel will
+automatically load balance processes in that cpuset over
+the allowed CPUs in that cpuset.
+If cleared (0) the
+kernel will avoid load balancing processes in this cpuset,
+.I unless
+some other cpuset with overlapping CPUs has its
+.I sched_load_balance
+flag set.
+See \fBScheduler Load Balancing\fR, below, for further details.
+.\" ================== sched_relax_domain_level ==================
+.TP
+.IR cpuset.sched_relax_domain_level " (since Linux 2.6.26)"
+Integer, between \-1 and a small positive value.
+The
+.I sched_relax_domain_level
+controls the width of the range of CPUs over which the kernel scheduler
+performs immediate rebalancing of runnable tasks across CPUs.
+If
+.I sched_load_balance
+is disabled, then the setting of
+.I sched_relax_domain_level
+does not matter, as no such load balancing is done.
+If
+.I sched_load_balance
+is enabled, then the higher the value of the
+.IR sched_relax_domain_level ,
+the wider
+the range of CPUs over which immediate load balancing is attempted.
+See \fBScheduler Relax Domain Level\fR, below, for further details.
+.\" ================== proc cpuset ==================
+.P
+In addition to the above pseudo-files in each directory below
+.IR /dev/cpuset ,
+each process has a pseudo-file,
+.IR /proc/ pid /cpuset ,
+that displays the path of the process's cpuset directory
+relative to the root of the cpuset filesystem.
+.\" ================== proc status ==================
+.P
+Also the
+.IR /proc/ pid /status
+file for each process has four added lines,
+displaying the process's
+.I Cpus_allowed
+(on which CPUs it may be scheduled) and
+.I Mems_allowed
+(on which memory nodes it may obtain memory),
+in the two formats \fBMask Format\fR and \fBList Format\fR (see below)
+as shown in the following example:
+.P
+.in +4n
+.EX
+Cpus_allowed:   ffffffff,ffffffff,ffffffff,ffffffff
+Cpus_allowed_list:     0\-127
+Mems_allowed:   ffffffff,ffffffff
+Mems_allowed_list:     0\-63
+.EE
+.in
+.P
+The "allowed" fields were added in Linux 2.6.24;
+the "allowed_list" fields were added in Linux 2.6.26.
+.\" ================== EXTENDED CAPABILITIES ==================
+.SH EXTENDED CAPABILITIES
+In addition to controlling which
+.I cpus
+and
+.I mems
+a process is allowed to use, cpusets provide the following
+extended capabilities.
+.\" ================== Exclusive Cpusets ==================
+.SS Exclusive cpusets
+If a cpuset is marked
+.I cpu_exclusive
+or
+.IR mem_exclusive ,
+no other cpuset, other than a direct ancestor or descendant,
+may share any of the same CPUs or memory nodes.
+.P
+A cpuset that is
+.I mem_exclusive
+restricts kernel allocations for
+buffer cache pages and other internal kernel data pages
+commonly shared by the kernel across
+multiple users.
+All cpusets, whether
+.I mem_exclusive
+or not, restrict allocations of memory for user space.
+This enables configuring a
+system so that several independent jobs can share common kernel data,
+while isolating each job's user allocation in
+its own cpuset.
+To do this, construct a large
+.I mem_exclusive
+cpuset to hold all the jobs, and construct child,
+.RI non- mem_exclusive
+cpusets for each individual job.
+Only a small amount of kernel memory,
+such as requests from interrupt handlers, is allowed to be
+placed on memory nodes
+outside even a
+.I mem_exclusive
+cpuset.
+.\" ================== Hardwall ==================
+.SS Hardwall
+A cpuset that has
+.I mem_exclusive
+or
+.I mem_hardwall
+set is a
+.I hardwall
+cpuset.
+A
+.I hardwall
+cpuset restricts kernel allocations for page, buffer,
+and other data commonly shared by the kernel across multiple users.
+All cpusets, whether
+.I hardwall
+or not, restrict allocations of memory for user space.
+.P
+This enables configuring a system so that several independent
+jobs can share common kernel data, such as filesystem pages,
+while isolating each job's user allocation in its own cpuset.
+To do this, construct a large
+.I hardwall
+cpuset to hold
+all the jobs, and construct child cpusets for each individual
+job which are not
+.I hardwall
+cpusets.
+.P
+Only a small amount of kernel memory, such as requests from
+interrupt handlers, is allowed to be taken outside even a
+.I hardwall
+cpuset.
+.\" ================== Notify On Release ==================
+.SS Notify on release
+If the
+.I notify_on_release
+flag is enabled (1) in a cpuset,
+then whenever the last process in the cpuset leaves
+(exits or attaches to some other cpuset)
+and the last child cpuset of that cpuset is removed,
+the kernel will run the command
+.IR /sbin/cpuset_release_agent ,
+supplying the pathname (relative to the mount point of the
+cpuset filesystem) of the abandoned cpuset.
+This enables automatic removal of abandoned cpusets.
+.P
+The default value of
+.I notify_on_release
+in the root cpuset at system boot is disabled (0).
+The default value of other cpusets at creation
+is the current value of their parent's
+.I notify_on_release
+setting.
+.P
+The command
+.I /sbin/cpuset_release_agent
+is invoked, with the name
+.RI ( /dev/cpuset
+relative path)
+of the to-be-released cpuset in
+.IR argv[1] .
+.P
+The usual contents of the command
+.I /sbin/cpuset_release_agent
+is simply the shell script:
+.P
+.in +4n
+.EX
+#!/bin/sh
+rmdir /dev/cpuset/$1
+.EE
+.in
+.P
+As with other flag values below, this flag can
+be changed by writing an ASCII
+number 0 or 1 (with optional trailing newline)
+into the file, to clear or set the flag, respectively.
+.\" ================== Memory Pressure ==================
+.SS Memory pressure
+The
+.I memory_pressure
+of a cpuset provides a simple per-cpuset running average of
+the rate that the processes in a cpuset are attempting to free up in-use
+memory on the nodes of the cpuset to satisfy additional memory requests.
+.P
+This enables batch managers that are monitoring jobs running in dedicated
+cpusets to efficiently detect what level of memory pressure that job
+is causing.
+.P
+This is useful both on tightly managed systems running a wide mix of
+submitted jobs, which may choose to terminate or reprioritize jobs that
+are trying to use more memory than allowed on the nodes assigned them,
+and with tightly coupled, long-running, massively parallel scientific
+computing jobs that will dramatically fail to meet required performance
+goals if they start to use more memory than allowed to them.
+.P
+This mechanism provides a very economical way for the batch manager
+to monitor a cpuset for signs of memory pressure.
+It's up to the batch manager or other user code to decide
+what action to take if it detects signs of memory pressure.
+.P
+Unless memory pressure calculation is enabled by setting the pseudo-file
+.IR /dev/cpuset/cpuset.memory_pressure_enabled ,
+it is not computed for any cpuset, and reads from any
+.I memory_pressure
+always return zero, as represented by the ASCII string "0\en".
+See the \fBWARNINGS\fR section, below.
+.P
+A per-cpuset, running average is employed for the following reasons:
+.IP \[bu] 3
+Because this meter is per-cpuset rather than per-process or per virtual
+memory region, the system load imposed by a batch scheduler monitoring
+this metric is sharply reduced on large systems, because a scan of
+the tasklist can be avoided on each set of queries.
+.IP \[bu]
+Because this meter is a running average rather than an accumulating
+counter, a batch scheduler can detect memory pressure with a
+single read, instead of having to read and accumulate results
+for a period of time.
+.IP \[bu]
+Because this meter is per-cpuset rather than per-process,
+the batch scheduler can obtain the key information\[em]memory
+pressure in a cpuset\[em]with a single read, rather than having to
+query and accumulate results over all the (dynamically changing)
+set of processes in the cpuset.
+.P
+The
+.I memory_pressure
+of a cpuset is calculated using a per-cpuset simple digital filter
+that is kept within the kernel.
+For each cpuset, this filter tracks
+the recent rate at which processes attached to that cpuset enter the
+kernel direct reclaim code.
+.P
+The kernel direct reclaim code is entered whenever a process has to
+satisfy a memory page request by first finding some other page to
+repurpose, due to lack of any readily available already free pages.
+Dirty filesystem pages are repurposed by first writing them
+to disk.
+Unmodified filesystem buffer pages are repurposed
+by simply dropping them, though if that page is needed again, it
+will have to be reread from disk.
+.P
+The
+.I cpuset.memory_pressure
+file provides an integer number representing the recent (half-life of
+10 seconds) rate of entries to the direct reclaim code caused by any
+process in the cpuset, in units of reclaims attempted per second,
+times 1000.
+.\" ================== Memory Spread ==================
+.SS Memory spread
+There are two Boolean flag files per cpuset that control where the
+kernel allocates pages for the filesystem buffers and related
+in-kernel data structures.
+They are called
+.I cpuset.memory_spread_page
+and
+.IR cpuset.memory_spread_slab .
+.P
+If the per-cpuset Boolean flag file
+.I cpuset.memory_spread_page
+is set, then
+the kernel will spread the filesystem buffers (page cache) evenly
+over all the nodes that the faulting process is allowed to use, instead
+of preferring to put those pages on the node where the process is running.
+.P
+If the per-cpuset Boolean flag file
+.I cpuset.memory_spread_slab
+is set,
+then the kernel will spread some filesystem-related slab caches,
+such as those for inodes and directory entries, evenly over all the nodes
+that the faulting process is allowed to use, instead of preferring to
+put those pages on the node where the process is running.
+.P
+The setting of these flags does not affect the data segment
+(see
+.BR brk (2))
+or stack segment pages of a process.
+.P
+By default, both kinds of memory spreading are off and the kernel
+prefers to allocate memory pages on the node local to where the
+requesting process is running.
+If that node is not allowed by the
+process's NUMA memory policy or cpuset configuration or if there are
+insufficient free memory pages on that node, then the kernel looks
+for the nearest node that is allowed and has sufficient free memory.
+.P
+When new cpusets are created, they inherit the memory spread settings
+of their parent.
+.P
+Setting memory spreading causes allocations for the affected page or
+slab caches to ignore the process's NUMA memory policy and be spread
+instead.
+However, the effect of these changes in memory placement
+caused by cpuset-specified memory spreading is hidden from the
+.BR mbind (2)
+or
+.BR set_mempolicy (2)
+calls.
+These two NUMA memory policy calls always appear to behave as if
+no cpuset-specified memory spreading is in effect, even if it is.
+If cpuset memory spreading is subsequently turned off, the NUMA
+memory policy most recently specified by these calls is automatically
+reapplied.
+.P
+Both
+.I cpuset.memory_spread_page
+and
+.I cpuset.memory_spread_slab
+are Boolean flag files.
+By default, they contain "0", meaning that the feature is off
+for that cpuset.
+If a "1" is written to that file, that turns the named feature on.
+.P
+Cpuset-specified memory spreading behaves similarly to what is known
+(in other contexts) as round-robin or interleave memory placement.
+.P
+Cpuset-specified memory spreading can provide substantial performance
+improvements for jobs that:
+.IP \[bu] 3
+need to place thread-local data on
+memory nodes close to the CPUs which are running the threads that most
+frequently access that data; but also
+.IP \[bu]
+need to access large filesystem data sets that must to be spread
+across the several nodes in the job's cpuset in order to fit.
+.P
+Without this policy,
+the memory allocation across the nodes in the job's cpuset
+can become very uneven,
+especially for jobs that might have just a single
+thread initializing or reading in the data set.
+.\" ================== Memory Migration ==================
+.SS Memory migration
+Normally, under the default setting (disabled) of
+.IR cpuset.memory_migrate ,
+once a page is allocated (given a physical page
+of main memory), then that page stays on whatever node it
+was allocated, so long as it remains allocated, even if the
+cpuset's memory-placement policy
+.I mems
+subsequently changes.
+.P
+When memory migration is enabled in a cpuset, if the
+.I mems
+setting of the cpuset is changed, then any memory page in use by any
+process in the cpuset that is on a memory node that is no longer
+allowed will be migrated to a memory node that is allowed.
+.P
+Furthermore, if a process is moved into a cpuset with
+.I memory_migrate
+enabled, any memory pages it uses that were on memory nodes allowed
+in its previous cpuset, but which are not allowed in its new cpuset,
+will be migrated to a memory node allowed in the new cpuset.
+.P
+The relative placement of a migrated page within
+the cpuset is preserved during these migration operations if possible.
+For example,
+if the page was on the second valid node of the prior cpuset,
+then the page will be placed on the second valid node of the new cpuset,
+if possible.
+.\" ================== Scheduler Load Balancing ==================
+.SS Scheduler load balancing
+The kernel scheduler automatically load balances processes.
+If one CPU is underutilized,
+the kernel will look for processes on other more
+overloaded CPUs and move those processes to the underutilized CPU,
+within the constraints of such placement mechanisms as cpusets and
+.BR sched_setaffinity (2).
+.P
+The algorithmic cost of load balancing and its impact on key shared
+kernel data structures such as the process list increases more than
+linearly with the number of CPUs being balanced.
+For example, it
+costs more to load balance across one large set of CPUs than it does
+to balance across two smaller sets of CPUs, each of half the size
+of the larger set.
+(The precise relationship between the number of CPUs being balanced
+and the cost of load balancing depends
+on implementation details of the kernel process scheduler, which is
+subject to change over time, as improved kernel scheduler algorithms
+are implemented.)
+.P
+The per-cpuset flag
+.I sched_load_balance
+provides a mechanism to suppress this automatic scheduler load
+balancing in cases where it is not needed and suppressing it would have
+worthwhile performance benefits.
+.P
+By default, load balancing is done across all CPUs, except those
+marked isolated using the kernel boot time "isolcpus=" argument.
+(See \fBScheduler Relax Domain Level\fR, below, to change this default.)
+.P
+This default load balancing across all CPUs is not well suited to
+the following two situations:
+.IP \[bu] 3
+On large systems, load balancing across many CPUs is expensive.
+If the system is managed using cpusets to place independent jobs
+on separate sets of CPUs, full load balancing is unnecessary.
+.IP \[bu]
+Systems supporting real-time on some CPUs need to minimize
+system overhead on those CPUs, including avoiding process load
+balancing if that is not needed.
+.P
+When the per-cpuset flag
+.I sched_load_balance
+is enabled (the default setting),
+it requests load balancing across
+all the CPUs in that cpuset's allowed CPUs,
+ensuring that load balancing can move a process (not otherwise pinned,
+as by
+.BR sched_setaffinity (2))
+from any CPU in that cpuset to any other.
+.P
+When the per-cpuset flag
+.I sched_load_balance
+is disabled, then the
+scheduler will avoid load balancing across the CPUs in that cpuset,
+\fIexcept\fR in so far as is necessary because some overlapping cpuset
+has
+.I sched_load_balance
+enabled.
+.P
+So, for example, if the top cpuset has the flag
+.I sched_load_balance
+enabled, then the scheduler will load balance across all
+CPUs, and the setting of the
+.I sched_load_balance
+flag in other cpusets has no effect,
+as we're already fully load balancing.
+.P
+Therefore in the above two situations, the flag
+.I sched_load_balance
+should be disabled in the top cpuset, and only some of the smaller,
+child cpusets would have this flag enabled.
+.P
+When doing this, you don't usually want to leave any unpinned processes in
+the top cpuset that might use nontrivial amounts of CPU, as such processes
+may be artificially constrained to some subset of CPUs, depending on
+the particulars of this flag setting in descendant cpusets.
+Even if such a process could use spare CPU cycles in some other CPUs,
+the kernel scheduler might not consider the possibility of
+load balancing that process to the underused CPU.
+.P
+Of course, processes pinned to a particular CPU can be left in a cpuset
+that disables
+.I sched_load_balance
+as those processes aren't going anywhere else anyway.
+.\" ================== Scheduler Relax Domain Level ==================
+.SS Scheduler relax domain level
+The kernel scheduler performs immediate load balancing whenever
+a CPU becomes free or another task becomes runnable.
+This load
+balancing works to ensure that as many CPUs as possible are usefully
+employed running tasks.
+The kernel also performs periodic load
+balancing off the software clock described in
+.BR time (7).
+The setting of
+.I sched_relax_domain_level
+applies only to immediate load balancing.
+Regardless of the
+.I sched_relax_domain_level
+setting, periodic load balancing is attempted over all CPUs
+(unless disabled by turning off
+.IR sched_load_balance .)
+In any case, of course, tasks will be scheduled to run only on
+CPUs allowed by their cpuset, as modified by
+.BR sched_setaffinity (2)
+system calls.
+.P
+On small systems, such as those with just a few CPUs, immediate load
+balancing is useful to improve system interactivity and to minimize
+wasteful idle CPU cycles.
+But on large systems, attempting immediate
+load balancing across a large number of CPUs can be more costly than
+it is worth, depending on the particular performance characteristics
+of the job mix and the hardware.
+.P
+The exact meaning of the small integer values of
+.I sched_relax_domain_level
+will depend on internal
+implementation details of the kernel scheduler code and on the
+non-uniform architecture of the hardware.
+Both of these will evolve
+over time and vary by system architecture and kernel version.
+.P
+As of this writing, when this capability was introduced in Linux
+2.6.26, on certain popular architectures, the positive values of
+.I sched_relax_domain_level
+have the following meanings.
+.P
+.PD 0
+.TP
+.B 1
+Perform immediate load balancing across Hyper-Thread
+siblings on the same core.
+.TP
+.B 2
+Perform immediate load balancing across other cores in the same package.
+.TP
+.B 3
+Perform immediate load balancing across other CPUs
+on the same node or blade.
+.TP
+.B 4
+Perform immediate load balancing across over several
+(implementation detail) nodes [On NUMA systems].
+.TP
+.B 5
+Perform immediate load balancing across over all CPUs
+in system [On NUMA systems].
+.PD
+.P
+The
+.I sched_relax_domain_level
+value of zero (0) always means
+don't perform immediate load balancing,
+hence that load balancing is done only periodically,
+not immediately when a CPU becomes available or another task becomes
+runnable.
+.P
+The
+.I sched_relax_domain_level
+value of minus one (\-1)
+always means use the system default value.
+The system default value can vary by architecture and kernel version.
+This system default value can be changed by kernel
+boot-time "relax_domain_level=" argument.
+.P
+In the case of multiple overlapping cpusets which have conflicting
+.I sched_relax_domain_level
+values, then the highest such value
+applies to all CPUs in any of the overlapping cpusets.
+In such cases,
+.B \-1
+is the lowest value,
+overridden by any other value,
+and
+.B 0
+is the next lowest value.
+.SH FORMATS
+The following formats are used to represent sets of
+CPUs and memory nodes.
+.\" ================== Mask Format ==================
+.SS Mask format
+The \fBMask Format\fR is used to represent CPU and memory-node bit masks
+in the
+.IR /proc/ pid /status
+file.
+.P
+This format displays each 32-bit
+word in hexadecimal (using ASCII characters "0" - "9" and "a" - "f");
+words are filled with leading zeros, if required.
+For masks longer than one word, a comma separator is used between words.
+Words are displayed in big-endian
+order, which has the most significant bit first.
+The hex digits within a word are also in big-endian order.
+.P
+The number of 32-bit words displayed is the minimum number needed to
+display all bits of the bit mask, based on the size of the bit mask.
+.P
+Examples of the \fBMask Format\fR:
+.P
+.in +4n
+.EX
+00000001                        # just bit 0 set
+40000000,00000000,00000000      # just bit 94 set
+00000001,00000000,00000000      # just bit 64 set
+000000ff,00000000               # bits 32\-39 set
+00000000,000e3862               # 1,5,6,11\-13,17\-19 set
+.EE
+.in
+.P
+A mask with bits 0, 1, 2, 4, 8, 16, 32, and 64 set displays as:
+.P
+.in +4n
+.EX
+00000001,00000001,00010117
+.EE
+.in
+.P
+The first "1" is for bit 64, the
+second for bit 32, the third for bit 16, the fourth for bit 8, the
+fifth for bit 4, and the "7" is for bits 2, 1, and 0.
+.\" ================== List Format ==================
+.SS List format
+The \fBList Format\fR for
+.I cpus
+and
+.I mems
+is a comma-separated list of CPU or memory-node
+numbers and ranges of numbers, in ASCII decimal.
+.P
+Examples of the \fBList Format\fR:
+.P
+.in +4n
+.EX
+0\-4,9           # bits 0, 1, 2, 3, 4, and 9 set
+0\-2,7,12\-14     # bits 0, 1, 2, 7, 12, 13, and 14 set
+.EE
+.in
+.\" ================== RULES ==================
+.SH RULES
+The following rules apply to each cpuset:
+.IP \[bu] 3
+Its CPUs and memory nodes must be a (possibly equal)
+subset of its parent's.
+.IP \[bu]
+It can be marked
+.I cpu_exclusive
+only if its parent is.
+.IP \[bu]
+It can be marked
+.I mem_exclusive
+only if its parent is.
+.IP \[bu]
+If it is
+.IR cpu_exclusive ,
+its CPUs may not overlap any sibling.
+.IP \[bu]
+If it is
+.IR mem_exclusive ,
+its memory nodes may not overlap any sibling.
+.\" ================== PERMISSIONS ==================
+.SH PERMISSIONS
+The permissions of a cpuset are determined by the permissions
+of the directories and pseudo-files in the cpuset filesystem,
+normally mounted at
+.IR /dev/cpuset .
+.P
+For instance, a process can put itself in some other cpuset (than
+its current one) if it can write the
+.I tasks
+file for that cpuset.
+This requires execute permission on the encompassing directories
+and write permission on the
+.I tasks
+file.
+.P
+An additional constraint is applied to requests to place some
+other process in a cpuset.
+One process may not attach another to
+a cpuset unless it would have permission to send that process
+a signal (see
+.BR kill (2)).
+.P
+A process may create a child cpuset if it can access and write the
+parent cpuset directory.
+It can modify the CPUs or memory nodes
+in a cpuset if it can access that cpuset's directory (execute
+permissions on the each of the parent directories) and write the
+corresponding
+.I cpus
+or
+.I mems
+file.
+.P
+There is one minor difference between the manner in which these
+permissions are evaluated and the manner in which normal filesystem
+operation permissions are evaluated.
+The kernel interprets
+relative pathnames starting at a process's current working directory.
+Even if one is operating on a cpuset file, relative pathnames
+are interpreted relative to the process's current working directory,
+not relative to the process's current cpuset.
+The only ways that
+cpuset paths relative to a process's current cpuset can be used are
+if either the process's current working directory is its cpuset
+(it first did a
+.B cd
+or
+.BR chdir (2)
+to its cpuset directory beneath
+.IR /dev/cpuset ,
+which is a bit unusual)
+or if some user code converts the relative cpuset path to a
+full filesystem path.
+.P
+In theory, this means that user code should specify cpusets
+using absolute pathnames, which requires knowing the mount point of
+the cpuset filesystem (usually, but not necessarily,
+.IR /dev/cpuset ).
+In practice, all user level code that this author is aware of
+simply assumes that if the cpuset filesystem is mounted, then
+it is mounted at
+.IR /dev/cpuset .
+Furthermore, it is common practice for carefully written
+user code to verify the presence of the pseudo-file
+.I /dev/cpuset/tasks
+in order to verify that the cpuset pseudo-filesystem
+is currently mounted.
+.\" ================== WARNINGS ==================
+.SH WARNINGS
+.SS Enabling memory_pressure
+By default, the per-cpuset file
+.I cpuset.memory_pressure
+always contains zero (0).
+Unless this feature is enabled by writing "1" to the pseudo-file
+.IR /dev/cpuset/cpuset.memory_pressure_enabled ,
+the kernel does
+not compute per-cpuset
+.IR memory_pressure .
+.SS Using the echo command
+When using the
+.B echo
+command at the shell prompt to change the values of cpuset files,
+beware that the built-in
+.B echo
+command in some shells does not display an error message if the
+.BR write (2)
+system call fails.
+.\" Gack!  csh(1)'s echo does this
+For example, if the command:
+.P
+.in +4n
+.EX
+echo 19 > cpuset.mems
+.EE
+.in
+.P
+failed because memory node 19 was not allowed (perhaps
+the current system does not have a memory node 19), then the
+.B echo
+command might not display any error.
+It is better to use the
+.B /bin/echo
+external command to change cpuset file settings, as this
+command will display
+.BR write (2)
+errors, as in the example:
+.P
+.in +4n
+.EX
+/bin/echo 19 > cpuset.mems
+/bin/echo: write error: Invalid argument
+.EE
+.in
+.\" ================== EXCEPTIONS ==================
+.SH EXCEPTIONS
+.SS Memory placement
+Not all allocations of system memory are constrained by cpusets,
+for the following reasons.
+.P
+If hot-plug functionality is used to remove all the CPUs that are
+currently assigned to a cpuset, then the kernel will automatically
+update the
+.I cpus_allowed
+of all processes attached to CPUs in that cpuset
+to allow all CPUs.
+When memory hot-plug functionality for removing
+memory nodes is available, a similar exception is expected to apply
+there as well.
+In general, the kernel prefers to violate cpuset placement,
+rather than starving a process that has had all its allowed CPUs or
+memory nodes taken offline.
+User code should reconfigure cpusets to refer only to online CPUs
+and memory nodes when using hot-plug to add or remove such resources.
+.P
+A few kernel-critical, internal memory-allocation requests, marked
+GFP_ATOMIC, must be satisfied immediately.
+The kernel may drop some
+request or malfunction if one of these allocations fail.
+If such a request cannot be satisfied within the current process's cpuset,
+then we relax the cpuset, and look for memory anywhere we can find it.
+It's better to violate the cpuset than stress the kernel.
+.P
+Allocations of memory requested by kernel drivers while processing
+an interrupt lack any relevant process context, and are not confined
+by cpusets.
+.SS Renaming cpusets
+You can use the
+.BR rename (2)
+system call to rename cpusets.
+Only simple renaming is supported; that is, changing the name of a cpuset
+directory is permitted, but moving a directory into
+a different directory is not permitted.
+.\" ================== ERRORS ==================
+.SH ERRORS
+The Linux kernel implementation of cpusets sets
+.I errno
+to specify the reason for a failed system call affecting cpusets.
+.P
+The possible
+.I errno
+settings and their meaning when set on
+a failed cpuset call are as listed below.
+.TP
+.B E2BIG
+Attempted a
+.BR write (2)
+on a special cpuset file
+with a length larger than some kernel-determined upper
+limit on the length of such writes.
+.TP
+.B EACCES
+Attempted to
+.BR write (2)
+the process ID (PID) of a process to a cpuset
+.I tasks
+file when one lacks permission to move that process.
+.TP
+.B EACCES
+Attempted to add, using
+.BR write (2),
+a CPU or memory node to a cpuset, when that CPU or memory node was
+not already in its parent.
+.TP
+.B EACCES
+Attempted to set, using
+.BR write (2),
+.I cpuset.cpu_exclusive
+or
+.I cpuset.mem_exclusive
+on a cpuset whose parent lacks the same setting.
+.TP
+.B EACCES
+Attempted to
+.BR write (2)
+a
+.I cpuset.memory_pressure
+file.
+.TP
+.B EACCES
+Attempted to create a file in a cpuset directory.
+.TP
+.B EBUSY
+Attempted to remove, using
+.BR rmdir (2),
+a cpuset with attached processes.
+.TP
+.B EBUSY
+Attempted to remove, using
+.BR rmdir (2),
+a cpuset with child cpusets.
+.TP
+.B EBUSY
+Attempted to remove
+a CPU or memory node from a cpuset
+that is also in a child of that cpuset.
+.TP
+.B EEXIST
+Attempted to create, using
+.BR mkdir (2),
+a cpuset that already exists.
+.TP
+.B EEXIST
+Attempted to
+.BR rename (2)
+a cpuset to a name that already exists.
+.TP
+.B EFAULT
+Attempted to
+.BR read (2)
+or
+.BR write (2)
+a cpuset file using
+a buffer that is outside the writing processes accessible address space.
+.TP
+.B EINVAL
+Attempted to change a cpuset, using
+.BR write (2),
+in a way that would violate a
+.I cpu_exclusive
+or
+.I mem_exclusive
+attribute of that cpuset or any of its siblings.
+.TP
+.B EINVAL
+Attempted to
+.BR write (2)
+an empty
+.I cpuset.cpus
+or
+.I cpuset.mems
+list to a cpuset which has attached processes or child cpusets.
+.TP
+.B EINVAL
+Attempted to
+.BR write (2)
+a
+.I cpuset.cpus
+or
+.I cpuset.mems
+list which included a range with the second number smaller than
+the first number.
+.TP
+.B EINVAL
+Attempted to
+.BR write (2)
+a
+.I cpuset.cpus
+or
+.I cpuset.mems
+list which included an invalid character in the string.
+.TP
+.B EINVAL
+Attempted to
+.BR write (2)
+a list to a
+.I cpuset.cpus
+file that did not include any online CPUs.
+.TP
+.B EINVAL
+Attempted to
+.BR write (2)
+a list to a
+.I cpuset.mems
+file that did not include any online memory nodes.
+.TP
+.B EINVAL
+Attempted to
+.BR write (2)
+a list to a
+.I cpuset.mems
+file that included a node that held no memory.
+.TP
+.B EIO
+Attempted to
+.BR write (2)
+a string to a cpuset
+.I tasks
+file that
+does not begin with an ASCII decimal integer.
+.TP
+.B EIO
+Attempted to
+.BR rename (2)
+a cpuset into a different directory.
+.TP
+.B ENAMETOOLONG
+Attempted to
+.BR read (2)
+a
+.IR /proc/ pid /cpuset
+file for a cpuset path that is longer than the kernel page size.
+.TP
+.B ENAMETOOLONG
+Attempted to create, using
+.BR mkdir (2),
+a cpuset whose base directory name is longer than 255 characters.
+.TP
+.B ENAMETOOLONG
+Attempted to create, using
+.BR mkdir (2),
+a cpuset whose full pathname,
+including the mount point (typically "/dev/cpuset/") prefix,
+is longer than 4095 characters.
+.TP
+.B ENODEV
+The cpuset was removed by another process at the same time as a
+.BR write (2)
+was attempted on one of the pseudo-files in the cpuset directory.
+.TP
+.B ENOENT
+Attempted to create, using
+.BR mkdir (2),
+a cpuset in a parent cpuset that doesn't exist.
+.TP
+.B ENOENT
+Attempted to
+.BR access (2)
+or
+.BR open (2)
+a nonexistent file in a cpuset directory.
+.TP
+.B ENOMEM
+Insufficient memory is available within the kernel; can occur
+on a variety of system calls affecting cpusets, but only if the
+system is extremely short of memory.
+.TP
+.B ENOSPC
+Attempted to
+.BR write (2)
+the process ID (PID)
+of a process to a cpuset
+.I tasks
+file when the cpuset had an empty
+.I cpuset.cpus
+or empty
+.I cpuset.mems
+setting.
+.TP
+.B ENOSPC
+Attempted to
+.BR write (2)
+an empty
+.I cpuset.cpus
+or
+.I cpuset.mems
+setting to a cpuset that
+has tasks attached.
+.TP
+.B ENOTDIR
+Attempted to
+.BR rename (2)
+a nonexistent cpuset.
+.TP
+.B EPERM
+Attempted to remove a file from a cpuset directory.
+.TP
+.B ERANGE
+Specified a
+.I cpuset.cpus
+or
+.I cpuset.mems
+list to the kernel which included a number too large for the kernel
+to set in its bit masks.
+.TP
+.B ESRCH
+Attempted to
+.BR write (2)
+the process ID (PID) of a nonexistent process to a cpuset
+.I tasks
+file.
+.\" ================== VERSIONS ==================
+.SH VERSIONS
+Cpusets appeared in Linux 2.6.12.
+.\" ================== NOTES ==================
+.SH NOTES
+Despite its name, the
+.I pid
+parameter is actually a thread ID,
+and each thread in a threaded group can be attached to a different
+cpuset.
+The value returned from a call to
+.BR gettid (2)
+can be passed in the argument
+.IR pid .
+.\" ================== BUGS ==================
+.SH BUGS
+.I cpuset.memory_pressure
+cpuset files can be opened
+for writing, creation, or truncation, but then the
+.BR write (2)
+fails with
+.I errno
+set to
+.BR EACCES ,
+and the creation and truncation options on
+.BR open (2)
+have no effect.
+.\" ================== EXAMPLES ==================
+.SH EXAMPLES
+The following examples demonstrate querying and setting cpuset
+options using shell commands.
+.SS Creating and attaching to a cpuset.
+To create a new cpuset and attach the current command shell to it,
+the steps are:
+.P
+.PD 0
+.IP (1) 5
+mkdir /dev/cpuset (if not already done)
+.IP (2)
+mount \-t cpuset none /dev/cpuset (if not already done)
+.IP (3)
+Create the new cpuset using
+.BR mkdir (1).
+.IP (4)
+Assign CPUs and memory nodes to the new cpuset.
+.IP (5)
+Attach the shell to the new cpuset.
+.PD
+.P
+For example, the following sequence of commands will set up a cpuset
+named "Charlie", containing just CPUs 2 and 3, and memory node 1,
+and then attach the current shell to that cpuset.
+.P
+.in +4n
+.EX
+.RB "$" " mkdir /dev/cpuset"
+.RB "$" " mount \-t cpuset cpuset /dev/cpuset"
+.RB "$" " cd /dev/cpuset"
+.RB "$" " mkdir Charlie"
+.RB "$" " cd Charlie"
+.RB "$" " /bin/echo 2\-3 > cpuset.cpus"
+.RB "$" " /bin/echo 1 > cpuset.mems"
+.RB "$" " /bin/echo $$ > tasks"
+# The current shell is now running in cpuset Charlie
+# The next line should display \[aq]/Charlie\[aq]
+.RB "$" " cat /proc/self/cpuset"
+.EE
+.in
+.\"
+.SS Migrating a job to different memory nodes.
+To migrate a job (the set of processes attached to a cpuset)
+to different CPUs and memory nodes in the system, including moving
+the memory pages currently allocated to that job,
+perform the following steps.
+.P
+.PD 0
+.IP (1) 5
+Let's say we want to move the job in cpuset
+.I alpha
+(CPUs 4\[en]7 and memory nodes 2\[en]3) to a new cpuset
+.I beta
+(CPUs 16\[en]19 and memory nodes 8\[en]9).
+.IP (2)
+First create the new cpuset
+.IR beta .
+.IP (3)
+Then allow CPUs 16\[en]19 and memory nodes 8\[en]9 in
+.IR beta .
+.IP (4)
+Then enable
+.I memory_migration
+in
+.IR beta .
+.IP (5)
+Then move each process from
+.I alpha
+to
+.IR beta .
+.PD
+.P
+The following sequence of commands accomplishes this.
+.P
+.in +4n
+.EX
+.RB "$" " cd /dev/cpuset"
+.RB "$" " mkdir beta"
+.RB "$" " cd beta"
+.RB "$" " /bin/echo 16\-19 > cpuset.cpus"
+.RB "$" " /bin/echo 8\-9 > cpuset.mems"
+.RB "$" " /bin/echo 1 > cpuset.memory_migrate"
+.RB "$" " while read i; do /bin/echo $i; done < ../alpha/tasks > tasks"
+.EE
+.in
+.P
+The above should move any processes in
+.I alpha
+to
+.IR beta ,
+and any memory held by these processes on memory nodes 2\[en]3 to memory
+nodes 8\[en]9, respectively.
+.P
+Notice that the last step of the above sequence did not do:
+.P
+.in +4n
+.EX
+.RB "$" " cp ../alpha/tasks tasks"
+.EE
+.in
+.P
+The
+.I while
+loop, rather than the seemingly easier use of the
+.BR cp (1)
+command, was necessary because
+only one process PID at a time may be written to the
+.I tasks
+file.
+.P
+The same effect (writing one PID at a time) as the
+.I while
+loop can be accomplished more efficiently, in fewer keystrokes and in
+syntax that works on any shell, but alas more obscurely, by using the
+.B \-u
+(unbuffered) option of
+.BR sed (1):
+.P
+.in +4n
+.EX
+.RB "$" " sed \-un p < ../alpha/tasks > tasks"
+.EE
+.in
+.\" ================== SEE ALSO ==================
+.SH SEE ALSO
+.BR taskset (1),
+.BR get_mempolicy (2),
+.BR getcpu (2),
+.BR mbind (2),
+.BR sched_getaffinity (2),
+.BR sched_setaffinity (2),
+.BR sched_setscheduler (2),
+.BR set_mempolicy (2),
+.BR CPU_SET (3),
+.BR proc (5),
+.BR cgroups (7),
+.BR numa (7),
+.BR sched (7),
+.BR migratepages (8),
+.BR numactl (8)
+.P
+.I Documentation/admin\-guide/cgroup\-v1/cpusets.rst
+in the Linux kernel source tree
+.\" commit 45ce80fb6b6f9594d1396d44dd7e7c02d596fef8
+(or
+.I Documentation/cgroup\-v1/cpusets.txt
+before Linux 4.18, and
+.I Documentation/cpusets.txt
+before Linux 2.6.29)
diff --git a/man/man7/credentials.7 b/man/man7/credentials.7
new file mode 100644
index 000000000..02427a9e5
--- /dev/null
+++ b/man/man7/credentials.7
@@ -0,0 +1,384 @@
+.\" Copyright (c) 2007 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2007-06-13 Creation
+.\"
+.TH credentials 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+credentials \- process identifiers
+.SH DESCRIPTION
+.SS Process ID (PID)
+Each process has a unique nonnegative integer identifier
+that is assigned when the process is created using
+.BR fork (2).
+A process can obtain its PID using
+.BR getpid (2).
+A PID is represented using the type
+.I pid_t
+(defined in
+.IR <sys/types.h> ).
+.P
+PIDs are used in a range of system calls to identify the process
+affected by the call, for example:
+.BR kill (2),
+.BR ptrace (2),
+.BR setpriority (2),
+.\" .BR sched_rr_get_interval (2),
+.\" .BR sched_getaffinity (2),
+.\" .BR sched_setaffinity (2),
+.\" .BR sched_getparam (2),
+.\" .BR sched_setparam (2),
+.\" .BR sched_setscheduler (2),
+.\" .BR sched_getscheduler (2),
+.BR setpgid (2),
+.\" .BR getsid (2),
+.BR setsid (2),
+.BR sigqueue (3),
+and
+.BR waitpid (2).
+.\" .BR waitid (2),
+.\" .BR wait4 (2),
+.P
+A process's PID is preserved across an
+.BR execve (2).
+.SS Parent process ID (PPID)
+A process's parent process ID identifies the process that created
+this process using
+.BR fork (2).
+A process can obtain its PPID using
+.BR getppid (2).
+A PPID is represented using the type
+.IR pid_t .
+.P
+A process's PPID is preserved across an
+.BR execve (2).
+.SS Process group ID and session ID
+Each process has a session ID and a process group ID,
+both represented using the type
+.IR pid_t .
+A process can obtain its session ID using
+.BR getsid (2),
+and its process group ID using
+.BR getpgrp (2).
+.P
+A child created by
+.BR fork (2)
+inherits its parent's session ID and process group ID.
+A process's session ID and process group ID are preserved across an
+.BR execve (2).
+.P
+Sessions and process groups are abstractions devised to support shell
+job control.
+A process group (sometimes called a "job") is a collection of
+processes that share the same process group ID;
+the shell creates a new process group for the process(es) used
+to execute single command or pipeline (e.g., the two processes
+created to execute the command "ls\ |\ wc" are placed in the
+same process group).
+A process's group membership can be set using
+.BR setpgid (2).
+The process whose process ID is the same as its process group ID is the
+\fIprocess group leader\fP for that group.
+.P
+A session is a collection of processes that share the same session ID.
+All of the members of a process group also have the same session ID
+(i.e., all of the members of a process group always belong to the
+same session, so that sessions and process groups form a strict
+two-level hierarchy of processes.)
+A new session is created when a process calls
+.BR setsid (2),
+which creates a new session whose session ID is the same
+as the PID of the process that called
+.BR setsid (2).
+The creator of the session is called the \fIsession leader\fP.
+.P
+All of the processes in a session share a
+.IR "controlling terminal" .
+The controlling terminal is established when the session leader
+first opens a terminal (unless the
+.B O_NOCTTY
+flag is specified when calling
+.BR open (2)).
+A terminal may be the controlling terminal of at most one session.
+.P
+At most one of the jobs in a session may be the
+.IR "foreground job" ;
+other jobs in the session are
+.IR "background jobs" .
+Only the foreground job may read from the terminal;
+when a process in the background attempts to read from the terminal,
+its process group is sent a
+.B SIGTTIN
+signal, which suspends the job.
+If the
+.B TOSTOP
+flag has been set for the terminal (see
+.BR termios (3)),
+then only the foreground job may write to the terminal;
+writes from background jobs cause a
+.B SIGTTOU
+signal to be generated, which suspends the job.
+When terminal keys that generate a signal (such as the
+.I interrupt
+key, normally control-C)
+are pressed, the signal is sent to the processes in the foreground job.
+.P
+Various system calls and library functions
+may operate on all members of a process group,
+including
+.BR kill (2),
+.BR killpg (3),
+.BR getpriority (2),
+.BR setpriority (2),
+.BR ioprio_get (2),
+.BR ioprio_set (2),
+.BR waitid (2),
+and
+.BR waitpid (2).
+See also the discussion of the
+.BR F_GETOWN ,
+.BR F_GETOWN_EX ,
+.BR F_SETOWN ,
+and
+.B F_SETOWN_EX
+operations in
+.BR fcntl (2).
+.SS User and group identifiers
+Each process has various associated user and group IDs.
+These IDs are integers, respectively represented using the types
+.I uid_t
+and
+.I gid_t
+(defined in
+.IR <sys/types.h> ).
+.P
+On Linux, each process has the following user and group identifiers:
+.IP \[bu] 3
+Real user ID and real group ID.
+These IDs determine who owns the process.
+A process can obtain its real user (group) ID using
+.BR getuid (2)
+.RB ( getgid (2)).
+.IP \[bu]
+Effective user ID and effective group ID.
+These IDs are used by the kernel to determine the permissions
+that the process will have when accessing shared resources such
+as message queues, shared memory, and semaphores.
+On most UNIX systems, these IDs also determine the
+permissions when accessing files.
+However, Linux uses the filesystem IDs described below
+for this task.
+A process can obtain its effective user (group) ID using
+.BR geteuid (2)
+.RB ( getegid (2)).
+.IP \[bu]
+Saved set-user-ID and saved set-group-ID.
+These IDs are used in set-user-ID and set-group-ID programs to save
+a copy of the corresponding effective IDs that were set when
+the program was executed (see
+.BR execve (2)).
+A set-user-ID program can assume and drop privileges by
+switching its effective user ID back and forth between the values
+in its real user ID and saved set-user-ID.
+This switching is done via calls to
+.BR seteuid (2),
+.BR setreuid (2),
+or
+.BR setresuid (2).
+A set-group-ID program performs the analogous tasks using
+.BR setegid (2),
+.BR setregid (2),
+or
+.BR setresgid (2).
+A process can obtain its saved set-user-ID (set-group-ID) using
+.BR getresuid (2)
+.RB ( getresgid (2)).
+.IP \[bu]
+Filesystem user ID and filesystem group ID (Linux-specific).
+These IDs, in conjunction with the supplementary group IDs described
+below, are used to determine permissions for accessing files; see
+.BR path_resolution (7)
+for details.
+Whenever a process's effective user (group) ID is changed,
+the kernel also automatically changes the filesystem user (group) ID
+to the same value.
+Consequently, the filesystem IDs normally have the same values
+as the corresponding effective ID, and the semantics for file-permission
+checks are thus the same on Linux as on other UNIX systems.
+The filesystem IDs can be made to differ from the effective IDs
+by calling
+.BR setfsuid (2)
+and
+.BR setfsgid (2).
+.IP \[bu]
+Supplementary group IDs.
+This is a set of additional group IDs that are used for permission
+checks when accessing files and other shared resources.
+Before Linux 2.6.4,
+a process can be a member of up to 32 supplementary groups;
+since Linux 2.6.4,
+a process can be a member of up to 65536 supplementary groups.
+The call
+.I sysconf(_SC_NGROUPS_MAX)
+can be used to determine the number of supplementary groups
+of which a process may be a member.
+.\" Since Linux 2.6.4, the limit is visible via the read-only file
+.\" /proc/sys/kernel/ngroups_max.
+.\" As at 2.6.22-rc2, this file is still read-only.
+A process can obtain its set of supplementary group IDs using
+.BR getgroups (2).
+.P
+A child process created by
+.BR fork (2)
+inherits copies of its parent's user and groups IDs.
+During an
+.BR execve (2),
+a process's real user and group ID and supplementary
+group IDs are preserved;
+the effective and saved set IDs may be changed, as described in
+.BR execve (2).
+.P
+Aside from the purposes noted above,
+a process's user IDs are also employed in a number of other contexts:
+.IP \[bu] 3
+when determining the permissions for sending signals (see
+.BR kill (2));
+.IP \[bu]
+when determining the permissions for setting
+process-scheduling parameters (nice value, real time
+scheduling policy and priority, CPU affinity, I/O priority) using
+.BR setpriority (2),
+.BR sched_setaffinity (2),
+.BR sched_setscheduler (2),
+.BR sched_setparam (2),
+.BR sched_setattr (2),
+and
+.BR ioprio_set (2);
+.IP \[bu]
+when checking resource limits (see
+.BR getrlimit (2));
+.IP \[bu]
+when checking the limit on the number of inotify instances
+that the process may create (see
+.BR inotify (7)).
+.\"
+.SS Modifying process user and group IDs
+Subject to rules described in the relevant manual pages,
+a process can use the following APIs to modify its user and group IDs:
+.TP
+.BR setuid (2)\~(\c
+.BR setgid (2))
+Modify the process's real (and possibly effective and saved-set)
+user (group) IDs.
+.TP
+.BR seteuid (2)\~(\c
+.BR setegid (2))
+Modify the process's effective user (group) ID.
+.TP
+.BR setfsuid (2)\~(\c
+.BR setfsgid (2))
+Modify the process's filesystem user (group) ID.
+.TP
+.BR setreuid (2)\~(\c
+.BR setregid (2))
+Modify the process's real and effective (and possibly saved-set)
+user (group) IDs.
+.TP
+.BR setresuid (2)\~(\c
+.BR setresgid (2))
+Modify the process's real, effective, and saved-set user (group) IDs.
+.TP
+.BR setgroups (2)
+Modify the process's supplementary group list.
+.P
+Any changes to a process's effective user (group) ID
+are automatically carried over to the process's
+filesystem user (group) ID.
+Changes to a process's effective user or group ID can also affect the
+process "dumpable" attribute, as described in
+.BR prctl (2).
+.P
+Changes to process user and group IDs can affect the capabilities
+of the process, as described in
+.BR capabilities (7).
+.SH STANDARDS
+Process IDs, parent process IDs, process group IDs, and session IDs
+are specified in POSIX.1.
+The real, effective, and saved set user and groups IDs,
+and the supplementary group IDs, are specified in POSIX.1.
+.P
+The filesystem user and group IDs are a Linux extension.
+.SH NOTES
+Various fields in the
+.IR /proc/ pid /status
+file show the process credentials described above.
+See
+.BR proc (5)
+for further information.
+.P
+The POSIX threads specification requires that
+credentials are shared by all of the threads in a process.
+However, at the kernel level, Linux maintains separate user and group
+credentials for each thread.
+The NPTL threading implementation does some work to ensure
+that any change to user or group credentials
+(e.g., calls to
+.BR setuid (2),
+.BR setresuid (2))
+is carried through to all of the POSIX threads in a process.
+See
+.BR nptl (7)
+for further details.
+.SH SEE ALSO
+.BR bash (1),
+.BR csh (1),
+.BR groups (1),
+.BR id (1),
+.BR newgrp (1),
+.BR ps (1),
+.BR runuser (1),
+.BR setpriv (1),
+.BR sg (1),
+.BR su (1),
+.BR access (2),
+.BR execve (2),
+.BR faccessat (2),
+.BR fork (2),
+.BR getgroups (2),
+.BR getpgrp (2),
+.BR getpid (2),
+.BR getppid (2),
+.BR getsid (2),
+.BR kill (2),
+.BR setegid (2),
+.BR seteuid (2),
+.BR setfsgid (2),
+.BR setfsuid (2),
+.BR setgid (2),
+.BR setgroups (2),
+.BR setpgid (2),
+.BR setresgid (2),
+.BR setresuid (2),
+.BR setsid (2),
+.BR setuid (2),
+.BR waitpid (2),
+.BR euidaccess (3),
+.BR initgroups (3),
+.BR killpg (3),
+.BR tcgetpgrp (3),
+.BR tcgetsid (3),
+.BR tcsetpgrp (3),
+.BR group (5),
+.BR passwd (5),
+.BR shadow (5),
+.BR capabilities (7),
+.BR namespaces (7),
+.BR path_resolution (7),
+.BR pid_namespaces (7),
+.BR pthreads (7),
+.BR signal (7),
+.BR system_data_types (7),
+.BR unix (7),
+.BR user_namespaces (7),
+.BR sudo (8)
diff --git a/man/man7/ddp.7 b/man/man7/ddp.7
new file mode 100644
index 000000000..e52cd442b
--- /dev/null
+++ b/man/man7/ddp.7
@@ -0,0 +1,245 @@
+.\" This man page is Copyright (C) 1998 Alan Cox.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" $Id: ddp.7,v 1.3 1999/05/13 11:33:22 freitag Exp $
+.\"
+.TH ddp 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ddp \- Linux AppleTalk protocol implementation
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <netatalk/at.h>
+.P
+.IB ddp_socket " = socket(AF_APPLETALK, SOCK_DGRAM, 0);"
+.IB raw_socket " = socket(AF_APPLETALK, SOCK_RAW, " protocol ");"
+.fi
+.SH DESCRIPTION
+Linux implements the AppleTalk protocols described in
+.IR "Inside AppleTalk" .
+Only the DDP layer and AARP are present in
+the kernel.
+They are designed to be used via the
+.B netatalk
+protocol
+libraries.
+This page documents the interface for those who wish or need to
+use the DDP layer directly.
+.P
+The communication between AppleTalk and the user program works using a
+BSD-compatible socket interface.
+For more information on sockets, see
+.BR socket (7).
+.P
+An AppleTalk socket is created by calling the
+.BR socket (2)
+function with a
+.B AF_APPLETALK
+socket family argument.
+Valid socket types are
+.B SOCK_DGRAM
+to open a
+.B ddp
+socket or
+.B SOCK_RAW
+to open a
+.B raw
+socket.
+.I protocol
+is the AppleTalk protocol to be received or sent.
+For
+.B SOCK_RAW
+you must specify
+.BR ATPROTO_DDP .
+.P
+Raw sockets may be opened only by a process with effective user ID 0
+or when the process has the
+.B CAP_NET_RAW
+capability.
+.SS Address format
+An AppleTalk socket address is defined as a combination of a network number,
+a node number, and a port number.
+.P
+.in +4n
+.EX
+struct at_addr {
+    unsigned short s_net;
+    unsigned char  s_node;
+};
+\&
+struct sockaddr_atalk {
+    sa_family_t    sat_family;    /* address family */
+    unsigned char  sat_port;      /* port */
+    struct at_addr sat_addr;      /* net/node */
+};
+.EE
+.in
+.P
+.I sat_family
+is always set to
+.BR AF_APPLETALK .
+.I sat_port
+contains the port.
+The port numbers below 129 are known as
+.IR "reserved ports" .
+Only processes with the effective user ID 0 or the
+.B CAP_NET_BIND_SERVICE
+capability may
+.BR bind (2)
+to these sockets.
+.I sat_addr
+is the host address.
+The
+.I net
+member of
+.I struct at_addr
+contains the host network in network byte order.
+The value of
+.B AT_ANYNET
+is a
+wildcard and also implies \[lq]this network.\[rq]
+The
+.I node
+member of
+.I struct at_addr
+contains the host node number.
+The value of
+.B AT_ANYNODE
+is a
+wildcard and also implies \[lq]this node.\[rq] The value of
+.B ATADDR_BCAST
+is a link
+local broadcast address.
+.\" FIXME . this doesn't make sense [johnl]
+.SS Socket options
+No protocol-specific socket options are supported.
+.SS /proc interfaces
+IP supports a set of
+.I /proc
+interfaces to configure some global AppleTalk parameters.
+The parameters can be accessed by reading or writing files in the directory
+.IR /proc/sys/net/atalk/ .
+.TP
+.I aarp\-expiry\-time
+The time interval (in seconds) before an AARP cache entry expires.
+.TP
+.I aarp\-resolve\-time
+The time interval (in seconds) before an AARP cache entry is resolved.
+.TP
+.I aarp\-retransmit\-limit
+The number of retransmissions of an AARP query before the node is declared
+dead.
+.TP
+.I aarp\-tick\-time
+The timer rate (in seconds) for the timer driving AARP.
+.P
+The default values match the specification and should never need to be
+changed.
+.SS Ioctls
+All ioctls described in
+.BR socket (7)
+apply to DDP.
+.\" FIXME . Add a section about multicasting
+.SH ERRORS
+.TP
+.B EACCES
+The user tried to execute an operation without the necessary permissions.
+These include sending to a broadcast address without
+having the broadcast flag set,
+and trying to bind to a reserved port without effective user ID 0 or
+.BR CAP_NET_BIND_SERVICE .
+.TP
+.B EADDRINUSE
+Tried to bind to an address already in use.
+.TP
+.B EADDRNOTAVAIL
+A nonexistent interface was requested or the requested source address was
+not local.
+.TP
+.B EAGAIN
+Operation on a nonblocking socket would block.
+.TP
+.B EALREADY
+A connection operation on a nonblocking socket is already in progress.
+.TP
+.B ECONNABORTED
+A connection was closed during an
+.BR accept (2).
+.TP
+.B EHOSTUNREACH
+No routing table entry matches the destination address.
+.TP
+.B EINVAL
+Invalid argument passed.
+.TP
+.B EISCONN
+.BR connect (2)
+was called on an already connected socket.
+.TP
+.B EMSGSIZE
+Datagram is bigger than the DDP MTU.
+.TP
+.B ENODEV
+Network device not available or not capable of sending IP.
+.TP
+.B ENOENT
+.B SIOCGSTAMP
+was called on a socket where no packet arrived.
+.TP
+.BR ENOMEM " and " ENOBUFS
+Not enough memory available.
+.TP
+.B ENOPKG
+A kernel subsystem was not configured.
+.TP
+.BR ENOPROTOOPT " and " EOPNOTSUPP
+Invalid socket option passed.
+.TP
+.B ENOTCONN
+The operation is defined only on a connected socket, but the socket wasn't
+connected.
+.TP
+.B EPERM
+User doesn't have permission to set high priority,
+make a configuration change,
+or send signals to the requested process or group.
+.TP
+.B EPIPE
+The connection was unexpectedly closed or shut down by the other end.
+.TP
+.B ESOCKTNOSUPPORT
+The socket was unconfigured, or an unknown socket type was requested.
+.SH VERSIONS
+AppleTalk is supported by Linux 2.0 or higher.
+The
+.I /proc
+interfaces exist since Linux 2.2.
+.SH NOTES
+Be very careful with the
+.B SO_BROADCAST
+option; it is not privileged in Linux.
+It is easy to overload the network
+with careless sending to broadcast addresses.
+.SS Compatibility
+The basic AppleTalk socket interface is compatible with
+.B netatalk
+on BSD-derived systems.
+Many BSD systems fail to check
+.B SO_BROADCAST
+when sending broadcast frames; this can lead to compatibility problems.
+.P
+The
+raw
+socket mode is unique to Linux and exists to support the alternative CAP
+package and AppleTalk monitoring tools more easily.
+.SH BUGS
+There are too many inconsistent error values.
+.P
+The ioctls used to configure routing tables, devices,
+AARP tables, and other devices are not yet described.
+.SH SEE ALSO
+.BR recvmsg (2),
+.BR sendmsg (2),
+.BR capabilities (7),
+.BR socket (7)
diff --git a/man/man7/environ.7 b/man/man7/environ.7
new file mode 100644
index 000000000..f98359a3f
--- /dev/null
+++ b/man/man7/environ.7
@@ -0,0 +1,354 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"   Fri Apr  2 11:32:09 MET DST 1993
+.\" and Andries Brouwer (aeb@cwi.nl), Fri Feb 14 21:47:50 1997.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sun Jul 25 10:45:30 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Jul 21 21:25:26 1996 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Mon Oct 21 17:47:19 1996 by Eric S. Raymond (esr@thyrsus.com)
+.\" Modified Wed Aug 27 20:28:58 1997 by Nicolás Lichtmaier (nick@debian.org)
+.\" Modified Mon Sep 21 00:00:26 1998 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Wed Jan 24 06:37:24 2001 by Eric S. Raymond (esr@thyrsus.com)
+.\" Modified Thu Dec 13 23:53:27 2001 by Martin Schulze <joey@infodrom.org>
+.\"
+.TH environ 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+environ \- user environment
+.SH SYNOPSIS
+.nf
+.BI "extern char **" environ ;
+.fi
+.SH DESCRIPTION
+The variable
+.I environ
+points to an array of pointers to strings called the "environment".
+The last pointer in this array has the value NULL.
+This array of strings is made available to the process by the
+.BR execve (2)
+call when a new program is started.
+When a child process is created via
+.BR fork (2),
+it inherits a
+.I copy
+of its parent's environment.
+.P
+By convention, the strings in
+.I environ
+have the form "\fIname\fP\fB=\fP\fIvalue\fP".
+The name is case-sensitive and may not contain
+the character "\fB=\fP".
+The value can be anything that can be represented as a string.
+The name and the value may not contain an embedded null byte (\[aq]\e0\[aq]),
+since this is assumed to terminate the string.
+.P
+Environment variables may be placed in the shell's environment by the
+.I export
+command in
+.BR sh (1),
+or by the
+.I setenv
+command if you use
+.BR csh (1).
+.P
+The initial environment of the shell is populated in various ways,
+such as definitions from
+.I /etc/environment
+that are processed by
+.BR pam_env (8)
+for all users at login time (on systems that employ
+.BR pam (8)).
+In addition, various shell initialization scripts, such as the system-wide
+.I /etc/profile
+script and per-user initializations script may include commands
+that add variables to the shell's environment;
+see the manual page of your preferred shell for details.
+.P
+Bourne-style shells support the syntax
+.P
+.in +4n
+.EX
+NAME=value command
+.EE
+.in
+.P
+to create an environment variable definition only in the scope
+of the process that executes
+.IR command .
+Multiple variable definitions, separated by white space, may precede
+.IR command .
+.P
+Arguments may also be placed in the
+environment at the point of an
+.BR exec (3).
+A C program can manipulate its environment using the functions
+.BR getenv (3),
+.BR putenv (3),
+.BR setenv (3),
+and
+.BR unsetenv (3).
+.P
+What follows is a list of environment variables typically seen on a
+system.
+This list is incomplete and includes only common variables seen
+by average users in their day-to-day routine.
+Environment variables specific to a particular program or library function
+are documented in the ENVIRONMENT section of the appropriate manual page.
+.TP
+.B USER
+The name of the logged-in user (used by some BSD-derived programs).
+Set at login time, see section NOTES below.
+.TP
+.B LOGNAME
+The name of the logged-in user (used by some System-V derived programs).
+Set at login time, see section NOTES below.
+.TP
+.B HOME
+A user's login directory.
+Set at login time, see section NOTES below.
+.TP
+.B LANG
+The name of a locale to use for locale categories when not overridden
+by
+.B LC_ALL
+or more specific environment variables such as
+.BR LC_COLLATE ,
+.BR LC_CTYPE ,
+.BR LC_MESSAGES ,
+.BR LC_MONETARY ,
+.BR LC_NUMERIC ,
+and
+.B LC_TIME
+(see
+.BR locale (7)
+for further details of the
+.B LC_*
+environment variables).
+.TP
+.B PATH
+The sequence of directory prefixes that
+.BR sh (1)
+and many other
+programs employ when searching for an executable file that is specified
+as a simple filename (i.a., a pathname that contains no slashes).
+The prefixes are separated by colons (\fB:\fP).
+The list of prefixes is searched from beginning to end,
+by checking the pathname formed by concatenating
+a prefix, a slash, and the filename,
+until a file with execute permission is found.
+.IP
+As a legacy feature, a zero-length prefix
+(specified as two adjacent colons, or an initial or terminating colon)
+is interpreted to mean the current working directory.
+However, use of this feature is deprecated,
+and POSIX notes that a conforming application shall use
+an explicit pathname (e.g.,
+.IR . )
+to specify the current working directory.
+.IP
+Analogously to
+.BR PATH ,
+one has
+.B CDPATH
+used by some shells to find the target
+of a change directory command,
+.B MANPATH
+used by
+.BR man (1)
+to find manual pages, and so on.
+.TP
+.B PWD
+Absolute path to the current working directory;
+required to be partially canonical (no
+.I .\&
+or
+.I ..\&
+components).
+.TP
+.B SHELL
+The absolute pathname of the user's login shell.
+Set at login time, see section NOTES below.
+.TP
+.B TERM
+The terminal type for which output is to be prepared.
+.TP
+.B PAGER
+The user's preferred utility to display text files.
+Any string acceptable as a command-string operand to the
+.I sh\ \-c
+command shall be valid.
+If
+.B PAGER
+is null or is not set,
+then applications that launch a pager will default to a program such as
+.BR less (1)
+or
+.BR more (1).
+.TP
+.BR EDITOR / VISUAL
+The user's preferred utility to edit text files.
+Any string acceptable as a command_string operand to the
+.I sh\ \-c
+command shall be valid.
+.\" .TP
+.\" .B BROWSER
+.\" The user's preferred utility to browse URLs. Sequence of colon-separated
+.\" browser commands. See http://www.catb.org/\[ti]esr/BROWSER/ .
+.P
+Note that the behavior of many programs and library routines is
+influenced by the presence or value of certain environment variables.
+Examples include the following:
+.IP \[bu] 3
+The variables
+.BR LANG ", " LANGUAGE ", " NLSPATH ", " LOCPATH ,
+.BR LC_ALL ", " LC_MESSAGES ,
+and so on influence locale handling; see
+.BR catopen (3),
+.BR gettext (3),
+and
+.BR locale (7).
+.IP \[bu]
+.B TMPDIR
+influences the path prefix of names created by
+.BR tempnam (3)
+and other routines, and the temporary directory used by
+.BR sort (1)
+and other programs.
+.IP \[bu]
+.BR LD_LIBRARY_PATH ", " LD_PRELOAD ,
+and other
+.B LD_*
+variables influence the behavior of the dynamic loader/linker.
+See also
+.BR ld.so (8).
+.IP \[bu]
+.B POSIXLY_CORRECT
+makes certain programs and library routines follow
+the prescriptions of POSIX.
+.IP \[bu]
+The behavior of
+.BR malloc (3)
+is influenced by
+.B MALLOC_*
+variables.
+.IP \[bu]
+The variable
+.B HOSTALIASES
+gives the name of a file containing aliases
+to be used with
+.BR gethostbyname (3).
+.IP \[bu]
+.BR TZ " and " TZDIR
+give timezone information used by
+.BR tzset (3)
+and through that by functions like
+.BR ctime (3),
+.BR localtime (3),
+.BR mktime (3),
+.BR strftime (3).
+See also
+.BR tzselect (8).
+.IP \[bu]
+.B TERMCAP
+gives information on how to address a given terminal
+(or gives the name of a file containing such information).
+.IP \[bu]
+.BR COLUMNS " and " LINES
+tell applications about the window size, possibly overriding the actual size.
+.IP \[bu]
+.BR PRINTER " or " LPDEST
+may specify the desired printer to use.
+See
+.BR lpr (1).
+.SH NOTES
+Historically and by standard,
+.I environ
+must be declared in the user program.
+However, as a (nonstandard) programmer convenience,
+.I environ
+is declared in the header file
+.I <unistd.h>
+if the
+.B _GNU_SOURCE
+feature test macro is defined (see
+.BR feature_test_macros (7)).
+.P
+The
+.BR prctl (2)
+.B PR_SET_MM_ENV_START
+and
+.B PR_SET_MM_ENV_END
+operations can be used to control the location of the process's environment.
+.P
+The
+.BR HOME ,
+.BR LOGNAME ,
+.BR SHELL ,
+and
+.B USER
+variables are set when the user is changed via a
+session management interface, typically by a program such as
+.BR login (1)
+from a user database (such as
+.BR passwd (5)).
+(Switching to the root user using
+.BR su (1)
+may result in a mixed environment where
+.B LOGNAME
+and
+.B USER
+are retained from old user; see the
+.BR su (1)
+manual page.)
+.SH BUGS
+Clearly there is a security risk here.
+Many a system command has been
+tricked into mischief by a user who specified unusual values for
+.BR IFS " or " LD_LIBRARY_PATH .
+.P
+There is also the risk of name space pollution.
+Programs like
+.I make
+and
+.I autoconf
+allow overriding of default utility names from the
+environment with similarly named variables in all caps.
+Thus one uses
+.B CC
+to select the desired C compiler (and similarly
+.BR MAKE ,
+.BR AR ,
+.BR AS ,
+.BR FC ,
+.BR LD ,
+.BR LEX ,
+.BR RM ,
+.BR YACC ,
+etc.).
+However, in some traditional uses such an environment variable
+gives options for the program instead of a pathname.
+Thus, one has
+.B MORE
+and
+.BR LESS .
+Such usage is considered mistaken, and to be avoided in new
+programs.
+.SH SEE ALSO
+.BR bash (1),
+.BR csh (1),
+.BR env (1),
+.BR login (1),
+.BR printenv (1),
+.BR sh (1),
+.BR su (1),
+.BR tcsh (1),
+.BR execve (2),
+.BR clearenv (3),
+.BR exec (3),
+.BR getenv (3),
+.BR putenv (3),
+.BR setenv (3),
+.BR unsetenv (3),
+.BR locale (7),
+.BR ld.so (8),
+.BR pam_env (8)
diff --git a/man/man7/epoll.7 b/man/man7/epoll.7
new file mode 100644
index 000000000..e7892922e
--- /dev/null
+++ b/man/man7/epoll.7
@@ -0,0 +1,610 @@
+.\"  Copyright (C) 2003  Davide Libenzi
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\"  Davide Libenzi <davidel@xmailserver.org>
+.\"
+.TH epoll 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+epoll \- I/O event notification facility
+.SH SYNOPSIS
+.nf
+.B #include <sys/epoll.h>
+.fi
+.SH DESCRIPTION
+The
+.B epoll
+API performs a similar task to
+.BR poll (2):
+monitoring multiple file descriptors to see if I/O is possible on any of them.
+The
+.B epoll
+API can be used either as an edge-triggered or a level-triggered
+interface and scales well to large numbers of watched file descriptors.
+.P
+The central concept of the
+.B epoll
+API is the
+.B epoll
+.IR instance ,
+an in-kernel data structure which, from a user-space perspective,
+can be considered as a container for two lists:
+.IP \[bu] 3
+The
+.I interest
+list (sometimes also called the
+.B epoll
+set): the set of file descriptors that the process has registered
+an interest in monitoring.
+.IP \[bu]
+The
+.I ready
+list: the set of file descriptors that are "ready" for I/O.
+The ready list is a subset of
+(or, more precisely, a set of references to)
+the file descriptors in the interest list.
+The ready list is dynamically populated
+by the kernel as a result of I/O activity on those file descriptors.
+.P
+The following system calls are provided to
+create and manage an
+.B epoll
+instance:
+.IP \[bu] 3
+.BR epoll_create (2)
+creates a new
+.B epoll
+instance and returns a file descriptor referring to that instance.
+(The more recent
+.BR epoll_create1 (2)
+extends the functionality of
+.BR epoll_create (2).)
+.IP \[bu]
+Interest in particular file descriptors is then registered via
+.BR epoll_ctl (2),
+which adds items to the interest list of the
+.B epoll
+instance.
+.IP \[bu]
+.BR epoll_wait (2)
+waits for I/O events,
+blocking the calling thread if no events are currently available.
+(This system call can be thought of as fetching items from
+the ready list of the
+.B epoll
+instance.)
+.\"
+.SS Level-triggered and edge-triggered
+The
+.B epoll
+event distribution interface is able to behave both as edge-triggered
+(ET) and as level-triggered (LT).
+The difference between the two mechanisms
+can be described as follows.
+Suppose that
+this scenario happens:
+.IP (1) 5
+The file descriptor that represents the read side of a pipe
+.RI ( rfd )
+is registered on the
+.B epoll
+instance.
+.IP (2)
+A pipe writer writes 2\ kB of data on the write side of the pipe.
+.IP (3)
+A call to
+.BR epoll_wait (2)
+is done that will return
+.I rfd
+as a ready file descriptor.
+.IP (4)
+The pipe reader reads 1\ kB of data from
+.IR rfd .
+.IP (5)
+A call to
+.BR epoll_wait (2)
+is done.
+.P
+If the
+.I rfd
+file descriptor has been added to the
+.B epoll
+interface using the
+.B EPOLLET
+(edge-triggered)
+flag, the call to
+.BR epoll_wait (2)
+done in step
+.B 5
+will probably hang despite the available data still present in the file
+input buffer;
+meanwhile the remote peer might be expecting a response based on the
+data it already sent.
+The reason for this is that edge-triggered mode
+delivers events only when changes occur on the monitored file descriptor.
+So, in step
+.B 5
+the caller might end up waiting for some data that is already present inside
+the input buffer.
+In the above example, an event on
+.I rfd
+will be generated because of the write done in
+.B 2
+and the event is consumed in
+.BR 3 .
+Since the read operation done in
+.B 4
+does not consume the whole buffer data, the call to
+.BR epoll_wait (2)
+done in step
+.B 5
+might block indefinitely.
+.P
+An application that employs the
+.B EPOLLET
+flag should use nonblocking file descriptors to avoid having a blocking
+read or write starve a task that is handling multiple file descriptors.
+The suggested way to use
+.B epoll
+as an edge-triggered
+.RB ( EPOLLET )
+interface is as follows:
+.IP (1) 5
+with nonblocking file descriptors; and
+.IP (2)
+by waiting for an event only after
+.BR read (2)
+or
+.BR write (2)
+return
+.BR EAGAIN .
+.P
+By contrast, when used as a level-triggered interface
+(the default, when
+.B EPOLLET
+is not specified),
+.B epoll
+is simply a faster
+.BR poll (2),
+and can be used wherever the latter is used since it shares the
+same semantics.
+.P
+Since even with edge-triggered
+.BR epoll ,
+multiple events can be generated upon receipt of multiple chunks of data,
+the caller has the option to specify the
+.B EPOLLONESHOT
+flag, to tell
+.B epoll
+to disable the associated file descriptor after the receipt of an event with
+.BR epoll_wait (2).
+When the
+.B EPOLLONESHOT
+flag is specified,
+it is the caller's responsibility to rearm the file descriptor using
+.BR epoll_ctl (2)
+with
+.BR EPOLL_CTL_MOD .
+.P
+If multiple threads
+(or processes, if child processes have inherited the
+.B epoll
+file descriptor across
+.BR fork (2))
+are blocked in
+.BR epoll_wait (2)
+waiting on the same epoll file descriptor and a file descriptor
+in the interest list that is marked for edge-triggered
+.RB ( EPOLLET )
+notification becomes ready,
+just one of the threads (or processes) is awoken from
+.BR epoll_wait (2).
+This provides a useful optimization for avoiding "thundering herd" wake-ups
+in some scenarios.
+.\"
+.SS Interaction with autosleep
+If the system is in
+.B autosleep
+mode via
+.I /sys/power/autosleep
+and an event happens which wakes the device from sleep, the device
+driver will keep the device awake only until that event is queued.
+To keep the device awake until the event has been processed,
+it is necessary to use the
+.BR epoll_ctl (2)
+.B EPOLLWAKEUP
+flag.
+.P
+When the
+.B EPOLLWAKEUP
+flag is set in the
+.B events
+field for a
+.IR "struct epoll_event" ,
+the system will be kept awake from the moment the event is queued,
+through the
+.BR epoll_wait (2)
+call which returns the event until the subsequent
+.BR epoll_wait (2)
+call.
+If the event should keep the system awake beyond that time,
+then a separate
+.I wake_lock
+should be taken before the second
+.BR epoll_wait (2)
+call.
+.SS /proc interfaces
+The following interfaces can be used to limit the amount of
+kernel memory consumed by epoll:
+.\" Following was added in Linux 2.6.28, but them removed in Linux 2.6.29
+.\" .TP
+.\" .IR /proc/sys/fs/epoll/max_user_instances " (since Linux 2.6.28)"
+.\" This specifies an upper limit on the number of epoll instances
+.\" that can be created per real user ID.
+.TP
+.IR /proc/sys/fs/epoll/max_user_watches " (since Linux 2.6.28)"
+This specifies a limit on the total number of
+file descriptors that a user can register across
+all epoll instances on the system.
+The limit is per real user ID.
+Each registered file descriptor costs roughly 90 bytes on a 32-bit kernel,
+and roughly 160 bytes on a 64-bit kernel.
+Currently,
+.\" Linux 2.6.29 (in Linux 2.6.28, the default was 1/32 of lowmem)
+the default value for
+.I max_user_watches
+is 1/25 (4%) of the available low memory,
+divided by the registration cost in bytes.
+.SS Example for suggested usage
+While the usage of
+.B epoll
+when employed as a level-triggered interface does have the same
+semantics as
+.BR poll (2),
+the edge-triggered usage requires more clarification to avoid stalls
+in the application event loop.
+In this example, listener is a
+nonblocking socket on which
+.BR listen (2)
+has been called.
+The function
+.I do_use_fd()
+uses the new ready file descriptor until
+.B EAGAIN
+is returned by either
+.BR read (2)
+or
+.BR write (2).
+An event-driven state machine application should, after having received
+.BR EAGAIN ,
+record its current state so that at the next call to
+.I do_use_fd()
+it will continue to
+.BR read (2)
+or
+.BR write (2)
+from where it stopped before.
+.P
+.in +4n
+.EX
+#define MAX_EVENTS 10
+struct epoll_event ev, events[MAX_EVENTS];
+int listen_sock, conn_sock, nfds, epollfd;
+\&
+/* Code to set up listening socket, \[aq]listen_sock\[aq],
+   (socket(), bind(), listen()) omitted. */
+\&
+epollfd = epoll_create1(0);
+if (epollfd == \-1) {
+    perror("epoll_create1");
+    exit(EXIT_FAILURE);
+}
+\&
+ev.events = EPOLLIN;
+ev.data.fd = listen_sock;
+if (epoll_ctl(epollfd, EPOLL_CTL_ADD, listen_sock, &ev) == \-1) {
+    perror("epoll_ctl: listen_sock");
+    exit(EXIT_FAILURE);
+}
+\&
+for (;;) {
+    nfds = epoll_wait(epollfd, events, MAX_EVENTS, \-1);
+    if (nfds == \-1) {
+        perror("epoll_wait");
+        exit(EXIT_FAILURE);
+    }
+\&
+    for (n = 0; n < nfds; ++n) {
+        if (events[n].data.fd == listen_sock) {
+            conn_sock = accept(listen_sock,
+                               (struct sockaddr *) &addr, &addrlen);
+            if (conn_sock == \-1) {
+                perror("accept");
+                exit(EXIT_FAILURE);
+            }
+            setnonblocking(conn_sock);
+            ev.events = EPOLLIN | EPOLLET;
+            ev.data.fd = conn_sock;
+            if (epoll_ctl(epollfd, EPOLL_CTL_ADD, conn_sock,
+                        &ev) == \-1) {
+                perror("epoll_ctl: conn_sock");
+                exit(EXIT_FAILURE);
+            }
+        } else {
+            do_use_fd(events[n].data.fd);
+        }
+    }
+}
+.EE
+.in
+.P
+When used as an edge-triggered interface, for performance reasons, it is
+possible to add the file descriptor inside the
+.B epoll
+interface
+.RB ( EPOLL_CTL_ADD )
+once by specifying
+.RB ( EPOLLIN | EPOLLOUT ).
+This allows you to avoid
+continuously switching between
+.B EPOLLIN
+and
+.B EPOLLOUT
+calling
+.BR epoll_ctl (2)
+with
+.BR EPOLL_CTL_MOD .
+.SS Questions and answers
+.IP \[bu] 3
+What is the key used to distinguish the file descriptors registered in an
+interest list?
+.IP
+The key is the combination of the file descriptor number and
+the open file description
+(also known as an "open file handle",
+the kernel's internal representation of an open file).
+.IP \[bu]
+What happens if you register the same file descriptor on an
+.B epoll
+instance twice?
+.IP
+You will probably get
+.BR EEXIST .
+However, it is possible to add a duplicate
+.RB ( dup (2),
+.BR dup2 (2),
+.BR fcntl (2)
+.BR F_DUPFD )
+file descriptor to the same
+.B epoll
+instance.
+.\" But a file descriptor duplicated by fork(2) can't be added to the
+.\" set, because the [file *, fd] pair is already in the epoll set.
+.\" That is a somewhat ugly inconsistency.  On the one hand, a child process
+.\" cannot add the duplicate file descriptor to the epoll set.  (In every
+.\" other case that I can think of, file descriptors duplicated by fork have
+.\" similar semantics to file descriptors duplicated by dup() and friends.)  On
+.\" the other hand, the very fact that the child has a duplicate of the
+.\" file descriptor means that even if the parent closes its file descriptor,
+.\" then epoll_wait() in the parent will continue to receive notifications for
+.\" that file descriptor because of the duplicated file descriptor in the child.
+.\"
+.\" See http://thread.gmane.org/gmane.linux.kernel/596462/
+.\" "epoll design problems with common fork/exec patterns"
+.\"
+.\" mtk, Feb 2008
+This can be a useful technique for filtering events,
+if the duplicate file descriptors are registered with different
+.I events
+masks.
+.IP \[bu]
+Can two
+.B epoll
+instances wait for the same file descriptor?
+If so, are events reported to both
+.B epoll
+file descriptors?
+.IP
+Yes, and events would be reported to both.
+However, careful programming may be needed to do this correctly.
+.IP \[bu]
+Is the
+.B epoll
+file descriptor itself poll/epoll/selectable?
+.IP
+Yes.
+If an
+.B epoll
+file descriptor has events waiting, then it will
+indicate as being readable.
+.IP \[bu]
+What happens if one attempts to put an
+.B epoll
+file descriptor into its own file descriptor set?
+.IP
+The
+.BR epoll_ctl (2)
+call fails
+.RB ( EINVAL ).
+However, you can add an
+.B epoll
+file descriptor inside another
+.B epoll
+file descriptor set.
+.IP \[bu]
+Can I send an
+.B epoll
+file descriptor over a UNIX domain socket to another process?
+.IP
+Yes, but it does not make sense to do this, since the receiving process
+would not have copies of the file descriptors in the interest list.
+.IP \[bu]
+Will closing a file descriptor cause it to be removed from all
+.B epoll
+interest lists?
+.IP
+Yes, but be aware of the following point.
+A file descriptor is a reference to an open file description (see
+.BR open (2)).
+Whenever a file descriptor is duplicated via
+.BR dup (2),
+.BR dup2 (2),
+.BR fcntl (2)
+.BR F_DUPFD ,
+or
+.BR fork (2),
+a new file descriptor referring to the same open file description is
+created.
+An open file description continues to exist until all
+file descriptors referring to it have been closed.
+.IP
+A file descriptor is removed from an
+interest list only after all the file descriptors referring to the underlying
+open file description have been closed.
+This means that even after a file descriptor that is part of an
+interest list has been closed,
+events may be reported for that file descriptor if other file
+descriptors referring to the same underlying file description remain open.
+To prevent this happening,
+the file descriptor must be explicitly removed from the interest list (using
+.BR epoll_ctl (2)
+.BR EPOLL_CTL_DEL )
+before it is duplicated.
+Alternatively,
+the application must ensure that all file descriptors are closed
+(which may be difficult if file descriptors were duplicated
+behind the scenes by library functions that used
+.BR dup (2)
+or
+.BR fork (2)).
+.IP \[bu]
+If more than one event occurs between
+.BR epoll_wait (2)
+calls, are they combined or reported separately?
+.IP
+They will be combined.
+.IP \[bu]
+Does an operation on a file descriptor affect the
+already collected but not yet reported events?
+.IP
+You can do two operations on an existing file descriptor.
+Remove would be meaningless for
+this case.
+Modify will reread available I/O.
+.IP \[bu]
+Do I need to continuously read/write a file descriptor
+until
+.B EAGAIN
+when using the
+.B EPOLLET
+flag (edge-triggered behavior)?
+.IP
+Receiving an event from
+.BR epoll_wait (2)
+should suggest to you that such
+file descriptor is ready for the requested I/O operation.
+You must consider it ready until the next (nonblocking)
+read/write yields
+.BR EAGAIN .
+When and how you will use the file descriptor is entirely up to you.
+.IP
+For packet/token-oriented files (e.g., datagram socket,
+terminal in canonical mode),
+the only way to detect the end of the read/write I/O space
+is to continue to read/write until
+.BR EAGAIN .
+.IP
+For stream-oriented files (e.g., pipe, FIFO, stream socket), the
+condition that the read/write I/O space is exhausted can also be detected by
+checking the amount of data read from / written to the target file
+descriptor.
+For example, if you call
+.BR read (2)
+by asking to read a certain amount of data and
+.BR read (2)
+returns a lower number of bytes, you
+can be sure of having exhausted the read I/O space for the file
+descriptor.
+The same is true when writing using
+.BR write (2).
+(Avoid this latter technique if you cannot guarantee that
+the monitored file descriptor always refers to a stream-oriented file.)
+.SS Possible pitfalls and ways to avoid them
+.IP \[bu] 3
+.B Starvation (edge-triggered)
+.IP
+If there is a large amount of I/O space,
+it is possible that by trying to drain
+it the other files will not get processed causing starvation.
+(This problem is not specific to
+.BR epoll .)
+.IP
+The solution is to maintain a ready list
+and mark the file descriptor as ready
+in its associated data structure, thereby allowing the application to
+remember which files need to be processed but still round robin amongst
+all the ready files.
+This also supports ignoring subsequent events you
+receive for file descriptors that are already ready.
+.IP \[bu]
+.B If using an event cache...
+.IP
+If you use an event cache or store all the file descriptors returned from
+.BR epoll_wait (2),
+then make sure to provide a way to mark
+its closure dynamically (i.e., caused by
+a previous event's processing).
+Suppose you receive 100 events from
+.BR epoll_wait (2),
+and in event #47 a condition causes event #13 to be closed.
+If you remove the structure and
+.BR close (2)
+the file descriptor for event #13, then your
+event cache might still say there are events waiting for that
+file descriptor causing confusion.
+.IP
+One solution for this is to call, during the processing of event 47,
+.BR epoll_ctl ( EPOLL_CTL_DEL )
+to delete file descriptor 13 and
+.BR close (2),
+then mark its associated
+data structure as removed and link it to a cleanup list.
+If you find another
+event for file descriptor 13 in your batch processing,
+you will discover the file descriptor had been
+previously removed and there will be no confusion.
+.SH VERSIONS
+Some other systems provide similar mechanisms;
+for example,
+FreeBSD has
+.IR kqueue ,
+and Solaris has
+.IR /dev/poll .
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.5.44.
+.\" Its interface should be finalized in Linux 2.5.66.
+glibc 2.3.2.
+.SH NOTES
+The set of file descriptors that is being monitored via
+an epoll file descriptor can be viewed via the entry for
+the epoll file descriptor in the process's
+.IR /proc/ pid /fdinfo
+directory.
+See
+.BR proc (5)
+for further details.
+.P
+The
+.BR kcmp (2)
+.B KCMP_EPOLL_TFD
+operation can be used to test whether a file descriptor
+is present in an epoll instance.
+.SH SEE ALSO
+.BR epoll_create (2),
+.BR epoll_create1 (2),
+.BR epoll_ctl (2),
+.BR epoll_wait (2),
+.BR poll (2),
+.BR select (2)
diff --git a/man/man7/fanotify.7 b/man/man7/fanotify.7
new file mode 100644
index 000000000..07e445546
--- /dev/null
+++ b/man/man7/fanotify.7
@@ -0,0 +1,1456 @@
+.\" Copyright (C) 2013, Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\" and Copyright (C) 2014, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.TH fanotify 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fanotify \- monitoring filesystem events
+.SH DESCRIPTION
+The fanotify API provides notification and interception of
+filesystem events.
+Use cases include virus scanning and hierarchical storage management.
+In the original fanotify API, only a limited set of events was supported.
+In particular, there was no support for create, delete, and move events.
+The support for those events was added in Linux 5.1.
+(See
+.BR inotify (7)
+for details of an API that did notify those events pre Linux 5.1.)
+.P
+Additional capabilities compared to the
+.BR inotify (7)
+API include the ability to monitor all of the objects
+in a mounted filesystem,
+the ability to make access permission decisions, and the
+possibility to read or modify files before access by other applications.
+.P
+The following system calls are used with this API:
+.BR fanotify_init (2),
+.BR fanotify_mark (2),
+.BR read (2),
+.BR write (2),
+and
+.BR close (2).
+.SS fanotify_init(), fanotify_mark(), and notification groups
+The
+.BR fanotify_init (2)
+system call creates and initializes an fanotify notification group
+and returns a file descriptor referring to it.
+.P
+An fanotify notification group is a kernel-internal object that holds
+a list of files, directories, filesystems, and mounts for which
+events shall be created.
+.P
+For each entry in an fanotify notification group, two bit masks exist: the
+.I mark
+mask and the
+.I ignore
+mask.
+The mark mask defines file activities for which an event shall be created.
+The ignore mask defines activities for which no event shall be generated.
+Having these two types of masks permits a filesystem, mount, or
+directory to be marked for receiving events, while at the same time
+ignoring events for specific objects under a mount or directory.
+.P
+The
+.BR fanotify_mark (2)
+system call adds a file, directory, filesystem, or mount to a
+notification group and specifies which events
+shall be reported (or ignored), or removes or modifies such an entry.
+.P
+A possible usage of the ignore mask is for a file cache.
+Events of interest for a file cache are modification of a file and closing
+of the same.
+Hence, the cached directory or mount is to be marked to receive these
+events.
+After receiving the first event informing that a file has been modified,
+the corresponding cache entry will be invalidated.
+No further modification events for this file are of interest until the file
+is closed.
+Hence, the modify event can be added to the ignore mask.
+Upon receiving the close event, the modify event can be removed from the
+ignore mask and the file cache entry can be updated.
+.P
+The entries in the fanotify notification groups refer to files and
+directories via their inode number and to mounts via their mount ID.
+If files or directories are renamed or moved within the same mount,
+the respective entries survive.
+If files or directories are deleted or moved to another mount or if
+filesystems or mounts are unmounted, the corresponding entries are deleted.
+.SS The event queue
+As events occur on the filesystem objects monitored by a notification group,
+the fanotify system generates events that are collected in a queue.
+These events can then be read (using
+.BR read (2)
+or similar)
+from the fanotify file descriptor
+returned by
+.BR fanotify_init (2).
+.P
+Two types of events are generated:
+.I notification
+events and
+.I permission
+events.
+Notification events are merely informative and require no action to be taken
+by the receiving application with one exception: if a valid file descriptor
+is provided within a generic event, the file descriptor must be closed.
+Permission events are requests to the receiving application to decide
+whether permission for a file access shall be granted.
+For these events, the recipient must write a response which decides whether
+access is granted or not.
+.P
+An event is removed from the event queue of the fanotify group
+when it has been read.
+Permission events that have been read are kept in an internal list of the
+fanotify group until either a permission decision has been taken by
+writing to the fanotify file descriptor or the fanotify file descriptor
+is closed.
+.SS Reading fanotify events
+Calling
+.BR read (2)
+for the file descriptor returned by
+.BR fanotify_init (2)
+blocks (if the flag
+.B FAN_NONBLOCK
+is not specified in the call to
+.BR fanotify_init (2))
+until either a file event occurs or the call is interrupted by a signal
+(see
+.BR signal (7)).
+.P
+After a successful
+.BR read (2),
+the read buffer contains one or more of the following structures:
+.P
+.in +4n
+.EX
+struct fanotify_event_metadata {
+    __u32 event_len;
+    __u8 vers;
+    __u8 reserved;
+    __u16 metadata_len;
+    __aligned_u64 mask;
+    __s32 fd;
+    __s32 pid;
+};
+.EE
+.in
+.P
+Information records are
+supplemental pieces of information that
+may be provided alongside the generic
+.I fanotify_event_metadata
+structure.
+The
+.I flags
+passed to
+.BR fanotify_init (2)
+have influence over the type of information records that
+may be returned for an event.
+For example,
+if a notification group is initialized with
+.B FAN_REPORT_FID
+or
+.BR FAN_REPORT_DIR_FID ,
+then event listeners should also expect to receive a
+.I fanotify_event_info_fid
+structure alongside the
+.I fanotify_event_metadata
+structure,
+whereby file handles are used to
+identify filesystem objects
+rather than file descriptors.
+Information records may also be stacked,
+meaning that using the various
+.B FAN_REPORT_*
+flags in conjunction with one another is supported.
+In such cases,
+multiple information records can be returned for an event
+alongside the generic
+.I fanotify_event_metadata
+structure.
+For example,
+if a notification group is initialized with
+.B FAN_REPORT_TARGET_FID
+and
+.BR FAN_REPORT_PIDFD ,
+then an event listener should expect to receive up to two
+.I fanotify_event_info_fid
+information records and one
+.I fanotify_event_info_pidfd
+information record alongside the generic
+.I fanotify_event_metadata
+structure.
+Importantly,
+fanotify provides no guarantee around
+the ordering of information records
+when a notification group is initialized with a
+stacked based configuration.
+Each information record has a nested structure of type
+.IR fanotify_event_info_header .
+It is imperative for event listeners to inspect the
+.I info_type
+field of this structure in order to
+determine the type of information record that
+had been received for a given event.
+.P
+In cases where an fanotify group
+identifies filesystem objects by file handles,
+event listeners should also expect to
+receive one or more of the below
+information record objects alongside the generic
+.I fanotify_event_metadata
+structure within the read buffer:
+.P
+.in +4n
+.EX
+struct fanotify_event_info_fid {
+    struct fanotify_event_info_header hdr;
+    __kernel_fsid_t fsid;
+    unsigned char handle[];
+};
+.EE
+.in
+.P
+In cases where an fanotify group is initialized with
+.BR FAN_REPORT_PIDFD ,
+event listeners should expect to receive the below
+information record object alongside the generic
+.I fanotify_event_metadata
+structure within the read buffer:
+.P
+.in +4n
+.EX
+struct fanotify_event_info_pidfd {
+        struct fanotify_event_info_header hdr;
+        __s32 pidfd;
+};
+.EE
+.in
+.P
+In case of a
+.B FAN_FS_ERROR
+event,
+an additional information record describing the error that occurred
+is returned alongside the generic
+.I fanotify_event_metadata
+structure within the read buffer.
+This structure is defined as follows:
+.P
+.in +4n
+.EX
+struct fanotify_event_info_error {
+    struct fanotify_event_info_header hdr;
+    __s32 error;
+    __u32 error_count;
+};
+.EE
+.in
+.P
+All information records contain a nested structure of type
+.IR fanotify_event_info_header .
+This structure holds meta-information about the information record
+that may have been returned alongside the generic
+.I fanotify_event_metadata
+structure.
+This structure is defined as follows:
+.P
+.in +4n
+.EX
+struct fanotify_event_info_header {
+	__u8 info_type;
+	__u8 pad;
+	__u16 len;
+};
+.EE
+.in
+.P
+For performance reasons, it is recommended to use a large
+buffer size (for example, 4096 bytes),
+so that multiple events can be retrieved by a single
+.BR read (2).
+.P
+The return value of
+.BR read (2)
+is the number of bytes placed in the buffer,
+or \-1 in case of an error (but see BUGS).
+.P
+The fields of the
+.I fanotify_event_metadata
+structure are as follows:
+.TP
+.I event_len
+This is the length of the data for the current event and the offset
+to the next event in the buffer.
+Unless the group identifies filesystem objects by file handles, the value of
+.I event_len
+is always
+.BR FAN_EVENT_METADATA_LEN .
+For a group that identifies filesystem objects by file handles,
+.I event_len
+also includes the variable length file identifier records.
+.TP
+.I vers
+This field holds a version number for the structure.
+It must be compared to
+.B FANOTIFY_METADATA_VERSION
+to verify that the structures returned at run time match
+the structures defined at compile time.
+In case of a mismatch, the application should abandon trying to use the
+fanotify file descriptor.
+.TP
+.I reserved
+This field is not used.
+.TP
+.I metadata_len
+This is the length of the structure.
+The field was introduced to facilitate the implementation of
+optional headers per event type.
+No such optional headers exist in the current implementation.
+.TP
+.I mask
+This is a bit mask describing the event (see below).
+.TP
+.I fd
+This is an open file descriptor for the object being accessed, or
+.B FAN_NOFD
+if a queue overflow occurred.
+With an fanotify group that identifies filesystem objects by file handles,
+applications should expect this value to be set to
+.B FAN_NOFD
+for each event that is received.
+The file descriptor can be used to access the contents
+of the monitored file or directory.
+The reading application is responsible for closing this file descriptor.
+.IP
+When calling
+.BR fanotify_init (2),
+the caller may specify (via the
+.I event_f_flags
+argument) various file status flags that are to be set
+on the open file description that corresponds to this file descriptor.
+In addition, the (kernel-internal)
+.B FMODE_NONOTIFY
+file status flag is set on the open file description.
+This flag suppresses fanotify event generation.
+Hence, when the receiver of the fanotify event accesses the notified file or
+directory using this file descriptor, no additional events will be created.
+.TP
+.I pid
+If flag
+.B FAN_REPORT_TID
+was set in
+.BR fanotify_init (2),
+this is the TID of the thread that caused the event.
+Otherwise, this the PID of the process that caused the event.
+.P
+A program listening to fanotify events can compare this PID
+to the PID returned by
+.BR getpid (2),
+to determine whether the event is caused by the listener itself,
+or is due to a file access by another process.
+.P
+The bit mask in
+.I mask
+indicates which events have occurred for a single filesystem object.
+Multiple bits may be set in this mask,
+if more than one event occurred for the monitored filesystem object.
+In particular,
+consecutive events for the same filesystem object and originating from the
+same process may be merged into a single event, with the exception that two
+permission events are never merged into one queue entry.
+.P
+The bits that may appear in
+.I mask
+are as follows:
+.TP
+.B FAN_ACCESS
+A file or a directory (but see BUGS) was accessed (read).
+.TP
+.B FAN_OPEN
+A file or a directory was opened.
+.TP
+.B FAN_OPEN_EXEC
+A file was opened with the intent to be executed.
+See NOTES in
+.BR fanotify_mark (2)
+for additional details.
+.TP
+.B FAN_ATTRIB
+A file or directory metadata was changed.
+.TP
+.B FAN_CREATE
+A child file or directory was created in a watched parent.
+.TP
+.B FAN_DELETE
+A child file or directory was deleted in a watched parent.
+.TP
+.B FAN_DELETE_SELF
+A watched file or directory was deleted.
+.TP
+.B FAN_FS_ERROR
+A filesystem error was detected.
+.TP
+.B FAN_RENAME
+A file or directory has been moved to or from a watched parent directory.
+.TP
+.B FAN_MOVED_FROM
+A file or directory has been moved from a watched parent directory.
+.TP
+.B FAN_MOVED_TO
+A file or directory has been moved to a watched parent directory.
+.TP
+.B FAN_MOVE_SELF
+A watched file or directory was moved.
+.TP
+.B FAN_MODIFY
+A file was modified.
+.TP
+.B FAN_CLOSE_WRITE
+A file that was opened for writing
+.RB ( O_WRONLY
+or
+.BR O_RDWR )
+was closed.
+.TP
+.B FAN_CLOSE_NOWRITE
+A file or directory that was opened read-only
+.RB ( O_RDONLY )
+was closed.
+.TP
+.B FAN_Q_OVERFLOW
+The event queue exceeded the limit on number of events.
+This limit can be overridden by specifying the
+.B FAN_UNLIMITED_QUEUE
+flag when calling
+.BR fanotify_init (2).
+.TP
+.B FAN_ACCESS_PERM
+An application wants to read a file or directory, for example using
+.BR read (2)
+or
+.BR readdir (2).
+The reader must write a response (as described below)
+that determines whether the permission to
+access the filesystem object shall be granted.
+.TP
+.B FAN_OPEN_PERM
+An application wants to open a file or directory.
+The reader must write a response that determines whether the permission to
+open the filesystem object shall be granted.
+.TP
+.B FAN_OPEN_EXEC_PERM
+An application wants to open a file for execution.
+The reader must write a response that determines whether the permission to
+open the filesystem object for execution shall be granted.
+See NOTES in
+.BR fanotify_mark (2)
+for additional details.
+.P
+To check for any close event, the following bit mask may be used:
+.TP
+.B FAN_CLOSE
+A file was closed.
+This is a synonym for:
+.IP
+.in +4n
+.EX
+FAN_CLOSE_WRITE | FAN_CLOSE_NOWRITE
+.EE
+.in
+.P
+To check for any move event, the following bit mask may be used:
+.TP
+.B FAN_MOVE
+A file or directory was moved.
+This is a synonym for:
+.IP
+.in +4n
+.EX
+FAN_MOVED_FROM | FAN_MOVED_TO
+.EE
+.in
+.P
+The following bits may appear in
+.I mask
+only in conjunction with other event type bits:
+.TP
+.B FAN_ONDIR
+The events described in the
+.I mask
+have occurred on a directory object.
+Reporting events on directories requires setting this flag in the mark mask.
+See
+.BR fanotify_mark (2)
+for additional details.
+The
+.B FAN_ONDIR
+flag is reported in an event mask only if the fanotify group identifies
+filesystem objects by file handles.
+.P
+Information records that are supplied alongside the generic
+.I fanotify_event_metadata
+structure will always contain a nested structure of type
+.IR fanotify_event_info_header .
+The fields of the
+.I fanotify_event_info_header
+are as follows:
+.TP
+.I info_type
+A unique integer value representing
+the type of information record object received for an event.
+The value of this field can be set to one of the following:
+.BR FAN_EVENT_INFO_TYPE_FID ,
+.BR FAN_EVENT_INFO_TYPE_DFID ,
+.BR FAN_EVENT_INFO_TYPE_DFID_NAME ,
+or
+.BR FAN_EVENT_INFO_TYPE_PIDFD .
+The value set for this field
+is dependent on the flags that have been supplied to
+.BR fanotify_init (2).
+Refer to the field details of each information record object type below
+to understand the different cases in which the
+.I info_type
+values can be set.
+.TP
+.I pad
+This field is currently not used by any information record object type
+and therefore is set to zero.
+.TP
+.I len
+The value of
+.I len
+is set to the size of the information record object,
+including the
+.IR fanotify_event_info_header .
+The total size of all additional information records
+is not expected to be larger than
+.RI ( event_len
+\-
+.IR metadata_len ).
+.P
+The fields of the
+.I fanotify_event_info_fid
+structure are as follows:
+.TP
+.I hdr
+This is a structure of type
+.IR fanotify_event_info_header .
+For example, when an fanotify file descriptor is created using
+.BR FAN_REPORT_FID ,
+a single information record is expected to be attached to the event with
+.I info_type
+field value of
+.BR FAN_EVENT_INFO_TYPE_FID .
+When an fanotify file descriptor is created using the combination of
+.B FAN_REPORT_FID
+and
+.BR FAN_REPORT_DIR_FID ,
+there may be two information records attached to the event:
+one with
+.I info_type
+field value of
+.BR FAN_EVENT_INFO_TYPE_DFID ,
+identifying a parent directory object, and one with
+.I info_type
+field value of
+.BR FAN_EVENT_INFO_TYPE_FID ,
+identifying a child object.
+Note that for the directory entry modification events
+.BR FAN_CREATE ,
+.BR FAN_DELETE ,
+.BR FAN_MOVE ,
+and
+.BR FAN_RENAME ,
+an information record identifying the created/deleted/moved child object
+is reported only if an fanotify group was initialized with the flag
+.BR FAN_REPORT_TARGET_FID .
+.TP
+.I fsid
+This is a unique identifier of the filesystem containing the object
+associated with the event.
+It is a structure of type
+.I __kernel_fsid_t
+and contains the same value as
+.I f_fsid
+when calling
+.BR statfs (2).
+.TP
+.I handle
+This field contains a variable-length structure of type
+.IR "struct file_handle" .
+It is an opaque handle that corresponds to a specified object on a
+filesystem as returned by
+.BR name_to_handle_at (2).
+It can be used to uniquely identify a file on a filesystem and can be
+passed as an argument to
+.BR open_by_handle_at (2).
+If the value of
+.I info_type
+field is
+.BR FAN_EVENT_INFO_TYPE_DFID_NAME ,
+the file handle is followed by a null terminated string that identifies the
+created/deleted/moved directory entry name.
+For other events such as
+.BR FAN_OPEN ,
+.BR FAN_ATTRIB ,
+.BR FAN_DELETE_SELF ,
+and
+.BR FAN_MOVE_SELF ,
+if the value of
+.I info_type
+field is
+.BR FAN_EVENT_INFO_TYPE_FID ,
+the
+.I handle
+identifies the object correlated to the event.
+If the value of
+.I info_type
+field is
+.BR FAN_EVENT_INFO_TYPE_DFID ,
+the
+.I handle
+identifies the directory object correlated to the event or the parent directory
+of a non-directory object correlated to the event.
+If the value of
+.I info_type
+field is
+.BR FAN_EVENT_INFO_TYPE_DFID_NAME ,
+the
+.I handle
+identifies the same directory object that would be reported with
+.B FAN_EVENT_INFO_TYPE_DFID
+and the file handle is followed by a null terminated string that identifies the
+name of a directory entry in that directory, or '.' to identify the directory
+object itself.
+.P
+The fields of the
+.I fanotify_event_info_pidfd
+structure are as follows:
+.TP
+.I hdr
+This is a structure of type
+.IR fanotify_event_info_header .
+When an fanotify group is initialized using
+.BR FAN_REPORT_PIDFD ,
+the
+.I info_type
+field value of the
+.I fanotify_event_info_header
+is set to
+.BR FAN_EVENT_INFO_TYPE_PIDFD .
+.TP
+.I pidfd
+This is a process file descriptor that refers to
+the process responsible for generating the event.
+The returned process file descriptor is no different from
+one which could be obtained manually if
+.BR pidfd_open (2)
+were to be called on
+.IR fanotify_event_metadata.pid .
+In the instance that an error is encountered during pidfd creation,
+one of two possible error types represented by
+a negative integer value may be returned in this
+.I pidfd
+field.
+In cases where
+the process responsible for generating the event
+has terminated prior to
+the event listener being able to
+read events from the notification queue,
+.B FAN_NOPIDFD
+is returned.
+The pidfd creation for an event is only performed at the time the
+events are read from the notification queue.
+All other possible pidfd creation failures are represented by
+.BR FAN_EPIDFD .
+Once the event listener has dealt with an event
+and the pidfd is no longer required,
+the pidfd should be closed via
+.BR close (2).
+.P
+The fields of the
+.I fanotify_event_info_error
+structure are as follows:
+.TP
+.I hdr
+This is a structure of type
+.IR fanotify_event_info_header .
+The
+.I info_type
+field is set to
+.BR FAN_EVENT_INFO_TYPE_ERROR .
+.TP
+.I error
+Identifies the type of error that occurred.
+.TP
+.I error_count
+This is a counter of the number of errors suppressed
+since the last error was read.
+.P
+The following macros are provided to iterate over a buffer containing
+fanotify event metadata returned by a
+.BR read (2)
+from an fanotify file descriptor:
+.TP
+.B FAN_EVENT_OK(meta, len)
+This macro checks the remaining length
+.I len
+of the buffer
+.I meta
+against the length of the metadata structure and the
+.I event_len
+field of the first metadata structure in the buffer.
+.TP
+.B FAN_EVENT_NEXT(meta, len)
+This macro uses the length indicated in the
+.I event_len
+field of the metadata structure pointed to by
+.I meta
+to calculate the address of the next metadata structure that follows
+.IR meta .
+.I len
+is the number of bytes of metadata that currently remain in the buffer.
+The macro returns a pointer to the next metadata structure that follows
+.IR meta ,
+and reduces
+.I len
+by the number of bytes in the metadata structure that
+has been skipped over (i.e., it subtracts
+.I meta\->event_len
+from
+.IR len ).
+.P
+In addition, there is:
+.TP
+.B FAN_EVENT_METADATA_LEN
+This macro returns the size (in bytes) of the structure
+.IR fanotify_event_metadata .
+This is the minimum size (and currently the only size) of any event metadata.
+.\"
+.SS Monitoring an fanotify file descriptor for events
+When an fanotify event occurs, the fanotify file descriptor indicates as
+readable when passed to
+.BR epoll (7),
+.BR poll (2),
+or
+.BR select (2).
+.SS Dealing with permission events
+For permission events, the application must
+.BR write (2)
+a structure of the following form to the
+fanotify file descriptor:
+.P
+.in +4n
+.EX
+struct fanotify_response {
+    __s32 fd;
+    __u32 response;
+};
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I fd
+This is the file descriptor from the structure
+.IR fanotify_event_metadata .
+.TP
+.I response
+This field indicates whether or not the permission is to be granted.
+Its value must be either
+.B FAN_ALLOW
+to allow the file operation or
+.B FAN_DENY
+to deny the file operation.
+.P
+If access is denied, the requesting application call will receive an
+.B EPERM
+error.
+Additionally, if the notification group has been created with the
+.B FAN_ENABLE_AUDIT
+flag, then the
+.B FAN_AUDIT
+flag can be set in the
+.I response
+field.
+In that case, the audit subsystem will log information about the access
+decision to the audit logs.
+.\"
+.SS Monitoring filesystems for errors
+A single
+.B FAN_FS_ERROR
+event is stored per filesystem at once.
+Extra error messages are suppressed and accounted for in the
+.I error_count
+field of the existing
+.B FAN_FS_ERROR
+event record,
+but details about the errors are lost.
+.P
+Errors reported by
+.B FAN_FS_ERROR
+are generic
+.I errno
+values,
+but not all kinds of error types are reported by all filesystems.
+.P
+Errors not directly related to a file (i.e. super block corruption)
+are reported with an invalid
+.IR handle .
+For these errors, the
+.I handle
+will have the field
+.I handle_type
+set to
+.BR FILEID_INVALID ,
+and the handle buffer size set to
+.BR 0 .
+.\"
+.SS Closing the fanotify file descriptor
+When all file descriptors referring to the fanotify notification group are
+closed, the fanotify group is released and its resources
+are freed for reuse by the kernel.
+Upon
+.BR close (2),
+outstanding permission events will be set to allowed.
+.SS /proc interfaces
+The file
+.IR /proc/ pid /fdinfo/ fd
+contains information about fanotify marks for file descriptor
+.I fd
+of process
+.IR pid .
+See
+.BR proc (5)
+for details.
+.P
+Since Linux 5.13,
+.\" commit 5b8fea65d197f408bb00b251c70d842826d6b70b
+the following interfaces can be used to control the amount of
+kernel resources consumed by fanotify:
+.TP
+.I /proc/sys/fs/fanotify/max_queued_events
+The value in this file is used when an application calls
+.BR fanotify_init (2)
+to set an upper limit on the number of events that can be
+queued to the corresponding fanotify group.
+Events in excess of this limit are dropped, but an
+.B FAN_Q_OVERFLOW
+event is always generated.
+Prior to Linux kernel 5.13,
+.\" commit 5b8fea65d197f408bb00b251c70d842826d6b70b
+the hardcoded limit was 16384 events.
+.TP
+.I /proc/sys/fs/fanotify/max_user_group
+This specifies an upper limit on the number of fanotify groups
+that can be created per real user ID.
+Prior to Linux kernel 5.13,
+.\" commit 5b8fea65d197f408bb00b251c70d842826d6b70b
+the hardcoded limit was 128 groups per user.
+.TP
+.I /proc/sys/fs/fanotify/max_user_marks
+This specifies an upper limit on the number of fanotify marks
+that can be created per real user ID.
+Prior to Linux kernel 5.13,
+.\" commit 5b8fea65d197f408bb00b251c70d842826d6b70b
+the hardcoded limit was 8192 marks per group (not per user).
+.SH ERRORS
+In addition to the usual errors for
+.BR read (2),
+the following errors can occur when reading from the
+fanotify file descriptor:
+.TP
+.B EINVAL
+The buffer is too small to hold the event.
+.TP
+.B EMFILE
+The per-process limit on the number of open files has been reached.
+See the description of
+.B RLIMIT_NOFILE
+in
+.BR getrlimit (2).
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+See
+.I /proc/sys/fs/file\-max
+in
+.BR proc (5).
+.TP
+.B ETXTBSY
+This error is returned by
+.BR read (2)
+if
+.B O_RDWR
+or
+.B O_WRONLY
+was specified in the
+.I event_f_flags
+argument when calling
+.BR fanotify_init (2)
+and an event occurred for a monitored file that is currently being executed.
+.P
+In addition to the usual errors for
+.BR write (2),
+the following errors can occur when writing to the fanotify file descriptor:
+.TP
+.B EINVAL
+Fanotify access permissions are not enabled in the kernel configuration
+or the value of
+.I response
+in the response structure is not valid.
+.TP
+.B ENOENT
+The file descriptor
+.I fd
+in the response structure is not valid.
+This may occur when a response for the permission event has already been
+written.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+The fanotify API was introduced in Linux 2.6.36 and
+enabled in Linux 2.6.37.
+fdinfo support was added in Linux 3.8.
+.SH NOTES
+The fanotify API is available only if the kernel was built with the
+.B CONFIG_FANOTIFY
+configuration option enabled.
+In addition, fanotify permission handling is available only if the
+.B CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+configuration option is enabled.
+.SS Limitations and caveats
+Fanotify reports only events that a user-space program triggers through the
+filesystem API.
+As a result,
+it does not catch remote events that occur on network filesystems.
+.P
+The fanotify API does not report file accesses and modifications that
+may occur because of
+.BR mmap (2),
+.BR msync (2),
+and
+.BR munmap (2).
+.P
+Events for directories are created only if the directory itself is opened,
+read, and closed.
+Adding, removing, or changing children of a marked directory does not create
+events for the monitored directory itself.
+.P
+Fanotify monitoring of directories is not recursive:
+to monitor subdirectories under a directory,
+additional marks must be created.
+The
+.B FAN_CREATE
+event can be used for detecting when a subdirectory has been created under
+a marked directory.
+An additional mark must then be set on the newly created subdirectory.
+This approach is racy, because it can lose events that occurred inside the
+newly created subdirectory, before a mark is added on that subdirectory.
+Monitoring mounts offers the capability to monitor a whole directory tree
+in a race-free manner.
+Monitoring filesystems offers the capability to monitor changes made from
+any mount of a filesystem instance in a race-free manner.
+.P
+The event queue can overflow.
+In this case, events are lost.
+.SH BUGS
+Before Linux 3.19,
+.BR fallocate (2)
+did not generate fanotify events.
+Since Linux 3.19,
+.\" commit 820c12d5d6c0890bc93dd63893924a13041fdc35
+calls to
+.BR fallocate (2)
+generate
+.B FAN_MODIFY
+events.
+.P
+As of Linux 3.17,
+the following bugs exist:
+.IP \[bu] 3
+On Linux, a filesystem object may be accessible through multiple paths,
+for example, a part of a filesystem may be remounted using the
+.I \-\-bind
+option of
+.BR mount (8).
+A listener that marked a mount will be notified only of events that were
+triggered for a filesystem object using the same mount.
+Any other event will pass unnoticed.
+.IP \[bu]
+.\" FIXME . A patch was proposed.
+When an event is generated,
+no check is made to see whether the user ID of the
+receiving process has authorization to read or write the file
+before passing a file descriptor for that file.
+This poses a security risk, when the
+.B CAP_SYS_ADMIN
+capability is set for programs executed by unprivileged users.
+.IP \[bu]
+If a call to
+.BR read (2)
+processes multiple events from the fanotify queue and an error occurs,
+the return value will be the total length of the events successfully
+copied to the user-space buffer before the error occurred.
+The return value will not be \-1, and
+.I errno
+will not be set.
+Thus, the reading application has no way to detect the error.
+.SH EXAMPLES
+The two example programs below demonstrate the usage of the fanotify API.
+.SS Example program: fanotify_example.c
+The first program is an example of fanotify being
+used with its event object information passed in the form of a file
+descriptor.
+The program marks the mount passed as a command-line argument and
+waits for events of type
+.B FAN_OPEN_PERM
+and
+.BR FAN_CLOSE_WRITE .
+When a permission event occurs, a
+.B FAN_ALLOW
+response is given.
+.P
+The following shell session shows an example of
+running this program.
+This session involved editing the file
+.IR /home/user/temp/notes .
+Before the file was opened, a
+.B FAN_OPEN_PERM
+event occurred.
+After the file was closed, a
+.B FAN_CLOSE_WRITE
+event occurred.
+Execution of the program ends when the user presses the ENTER key.
+.P
+.in +4n
+.EX
+# \fB./fanotify_example /home\fP
+Press enter key to terminate.
+Listening for events.
+FAN_OPEN_PERM: File /home/user/temp/notes
+FAN_CLOSE_WRITE: File /home/user/temp/notes
+\&
+Listening for events stopped.
+.EE
+.in
+.SS Program source: fanotify_example.c
+\&
+.EX
+#define _GNU_SOURCE     /* Needed to get O_LARGEFILE definition */
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/fanotify.h>
+#include <unistd.h>
+\&
+/* Read all available fanotify events from the file descriptor \[aq]fd\[aq]. */
+\&
+static void
+handle_events(int fd)
+{
+    const struct fanotify_event_metadata *metadata;
+    struct fanotify_event_metadata buf[200];
+    ssize_t len;
+    char path[PATH_MAX];
+    ssize_t path_len;
+    char procfd_path[PATH_MAX];
+    struct fanotify_response response;
+\&
+    /* Loop while events can be read from fanotify file descriptor. */
+\&
+    for (;;) {
+\&
+        /* Read some events. */
+\&
+        len = read(fd, buf, sizeof(buf));
+        if (len == \-1 && errno != EAGAIN) {
+            perror("read");
+            exit(EXIT_FAILURE);
+        }
+\&
+        /* Check if end of available data reached. */
+\&
+        if (len <= 0)
+            break;
+\&
+        /* Point to the first event in the buffer. */
+\&
+        metadata = buf;
+\&
+        /* Loop over all events in the buffer. */
+\&
+        while (FAN_EVENT_OK(metadata, len)) {
+\&
+            /* Check that run\-time and compile\-time structures match. */
+\&
+            if (metadata\->vers != FANOTIFY_METADATA_VERSION) {
+                fprintf(stderr,
+                        "Mismatch of fanotify metadata version.\en");
+                exit(EXIT_FAILURE);
+            }
+\&
+            /* metadata\->fd contains either FAN_NOFD, indicating a
+               queue overflow, or a file descriptor (a nonnegative
+               integer). Here, we simply ignore queue overflow. */
+\&
+            if (metadata\->fd >= 0) {
+\&
+                /* Handle open permission event. */
+\&
+                if (metadata\->mask & FAN_OPEN_PERM) {
+                    printf("FAN_OPEN_PERM: ");
+\&
+                    /* Allow file to be opened. */
+\&
+                    response.fd = metadata\->fd;
+                    response.response = FAN_ALLOW;
+                    write(fd, &response, sizeof(response));
+                }
+\&
+                /* Handle closing of writable file event. */
+\&
+                if (metadata\->mask & FAN_CLOSE_WRITE)
+                    printf("FAN_CLOSE_WRITE: ");
+\&
+                /* Retrieve and print pathname of the accessed file. */
+\&
+                snprintf(procfd_path, sizeof(procfd_path),
+                         "/proc/self/fd/%d", metadata\->fd);
+                path_len = readlink(procfd_path, path,
+                                    sizeof(path) \- 1);
+                if (path_len == \-1) {
+                    perror("readlink");
+                    exit(EXIT_FAILURE);
+                }
+\&
+                path[path_len] = \[aq]\e0\[aq];
+                printf("File %s\en", path);
+\&
+                /* Close the file descriptor of the event. */
+\&
+                close(metadata\->fd);
+            }
+\&
+            /* Advance to next event. */
+\&
+            metadata = FAN_EVENT_NEXT(metadata, len);
+        }
+    }
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    char buf;
+    int fd, poll_num;
+    nfds_t nfds;
+    struct pollfd fds[2];
+\&
+    /* Check mount point is supplied. */
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s MOUNT\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Press enter key to terminate.\en");
+\&
+    /* Create the file descriptor for accessing the fanotify API. */
+\&
+    fd = fanotify_init(FAN_CLOEXEC | FAN_CLASS_CONTENT | FAN_NONBLOCK,
+                       O_RDONLY | O_LARGEFILE);
+    if (fd == \-1) {
+        perror("fanotify_init");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Mark the mount for:
+       \- permission events before opening files
+       \- notification events after closing a write\-enabled
+         file descriptor. */
+\&
+    if (fanotify_mark(fd, FAN_MARK_ADD | FAN_MARK_MOUNT,
+                      FAN_OPEN_PERM | FAN_CLOSE_WRITE, AT_FDCWD,
+                      argv[1]) == \-1) {
+        perror("fanotify_mark");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Prepare for polling. */
+\&
+    nfds = 2;
+\&
+    fds[0].fd = STDIN_FILENO;       /* Console input */
+    fds[0].events = POLLIN;
+\&
+    fds[1].fd = fd;                 /* Fanotify input */
+    fds[1].events = POLLIN;
+\&
+    /* This is the loop to wait for incoming events. */
+\&
+    printf("Listening for events.\en");
+\&
+    while (1) {
+        poll_num = poll(fds, nfds, \-1);
+        if (poll_num == \-1) {
+            if (errno == EINTR)     /* Interrupted by a signal */
+                continue;           /* Restart poll() */
+\&
+            perror("poll");         /* Unexpected error */
+            exit(EXIT_FAILURE);
+        }
+\&
+        if (poll_num > 0) {
+            if (fds[0].revents & POLLIN) {
+\&
+                /* Console input is available: empty stdin and quit. */
+\&
+                while (read(STDIN_FILENO, &buf, 1) > 0 && buf != \[aq]\en\[aq])
+                    continue;
+                break;
+            }
+\&
+            if (fds[1].revents & POLLIN) {
+\&
+                /* Fanotify events are available. */
+\&
+                handle_events(fd);
+            }
+        }
+    }
+\&
+    printf("Listening for events stopped.\en");
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\"
+.SS Example program: fanotify_fid.c
+The second program is an example of fanotify being used with a group that
+identifies objects by file handles.
+The program marks the filesystem object that is passed as
+a command-line argument
+and waits until an event of type
+.B FAN_CREATE
+has occurred.
+The event mask indicates which type of filesystem object\[em]either
+a file or a directory\[em]was created.
+Once all events have been read from the buffer and processed accordingly,
+the program simply terminates.
+.P
+The following shell sessions show two different invocations of
+this program, with different actions performed on a watched object.
+.P
+The first session shows a mark being placed on
+.IR /home/user .
+This is followed by the creation of a regular file,
+.IR /home/user/testfile.txt .
+This results in a
+.B FAN_CREATE
+event being generated and reported against the file's parent watched
+directory object and with the created file name.
+Program execution ends once all events captured within the buffer have
+been processed.
+.P
+.in +4n
+.EX
+# \fB./fanotify_fid /home/user\fP
+Listening for events.
+FAN_CREATE (file created):
+        Directory /home/user has been modified.
+        Entry \[aq]testfile.txt\[aq] is not a subdirectory.
+All events processed successfully. Program exiting.
+\&
+$ \fBtouch /home/user/testfile.txt\fP              # In another terminal
+.EE
+.in
+.P
+The second session shows a mark being placed on
+.IR /home/user .
+This is followed by the creation of a directory,
+.IR /home/user/testdir .
+This specific action results in a
+.B FAN_CREATE
+event being generated and is reported with the
+.B FAN_ONDIR
+flag set and with the created directory name.
+.P
+.in +4n
+.EX
+# \fB./fanotify_fid /home/user\fP
+Listening for events.
+FAN_CREATE | FAN_ONDIR (subdirectory created):
+        Directory /home/user has been modified.
+        Entry \[aq]testdir\[aq] is a subdirectory.
+All events processed successfully. Program exiting.
+\&
+$ \fBmkdir \-p /home/user/testdir\fP          # In another terminal
+.EE
+.in
+.SS Program source: fanotify_fid.c
+\&
+.EX
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/fanotify.h>
+#include <unistd.h>
+\&
+#define BUF_SIZE 256
+\&
+int
+main(int argc, char *argv[])
+{
+    int fd, ret, event_fd, mount_fd;
+    ssize_t len, path_len;
+    char path[PATH_MAX];
+    char procfd_path[PATH_MAX];
+    char events_buf[BUF_SIZE];
+    struct file_handle *file_handle;
+    struct fanotify_event_metadata *metadata;
+    struct fanotify_event_info_fid *fid;
+    const char *file_name;
+    struct stat sb;
+\&
+    if (argc != 2) {
+        fprintf(stderr, "Invalid number of command line arguments.\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    mount_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
+    if (mount_fd == \-1) {
+        perror(argv[1]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Create an fanotify file descriptor with FAN_REPORT_DFID_NAME as
+       a flag so that program can receive fid events with directory
+       entry name. */
+\&
+    fd = fanotify_init(FAN_CLASS_NOTIF | FAN_REPORT_DFID_NAME, 0);
+    if (fd == \-1) {
+        perror("fanotify_init");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Place a mark on the filesystem object supplied in argv[1]. */
+\&
+    ret = fanotify_mark(fd, FAN_MARK_ADD | FAN_MARK_ONLYDIR,
+                        FAN_CREATE | FAN_ONDIR,
+                        AT_FDCWD, argv[1]);
+    if (ret == \-1) {
+        perror("fanotify_mark");
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Listening for events.\en");
+\&
+    /* Read events from the event queue into a buffer. */
+\&
+    len = read(fd, events_buf, sizeof(events_buf));
+    if (len == \-1 && errno != EAGAIN) {
+        perror("read");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Process all events within the buffer. */
+\&
+    for (metadata = (struct fanotify_event_metadata *) events_buf;
+            FAN_EVENT_OK(metadata, len);
+            metadata = FAN_EVENT_NEXT(metadata, len)) {
+        fid = (struct fanotify_event_info_fid *) (metadata + 1);
+        file_handle = (struct file_handle *) fid\->handle;
+\&
+        /* Ensure that the event info is of the correct type. */
+\&
+        if (fid\->hdr.info_type == FAN_EVENT_INFO_TYPE_FID ||
+            fid\->hdr.info_type == FAN_EVENT_INFO_TYPE_DFID) {
+            file_name = NULL;
+        } else if (fid\->hdr.info_type == FAN_EVENT_INFO_TYPE_DFID_NAME) {
+            file_name = file_handle\->f_handle +
+                        file_handle\->handle_bytes;
+        } else {
+            fprintf(stderr, "Received unexpected event info type.\en");
+            exit(EXIT_FAILURE);
+        }
+\&
+        if (metadata\->mask == FAN_CREATE)
+            printf("FAN_CREATE (file created):\en");
+\&
+        if (metadata\->mask == (FAN_CREATE | FAN_ONDIR))
+            printf("FAN_CREATE | FAN_ONDIR (subdirectory created):\en");
+\&
+	/* metadata\->fd is set to FAN_NOFD when the group identifies
+	   objects by file handles.  To obtain a file descriptor for
+	   the file object corresponding to an event you can use the
+	   struct file_handle that\[aq]s provided within the
+	   fanotify_event_info_fid in conjunction with the
+	   open_by_handle_at(2) system call.  A check for ESTALE is
+	   done to accommodate for the situation where the file handle
+	   for the object was deleted prior to this system call. */
+\&
+        event_fd = open_by_handle_at(mount_fd, file_handle, O_RDONLY);
+        if (event_fd == \-1) {
+            if (errno == ESTALE) {
+                printf("File handle is no longer valid. "
+                        "File has been deleted\en");
+                continue;
+            } else {
+                perror("open_by_handle_at");
+                exit(EXIT_FAILURE);
+            }
+        }
+\&
+        snprintf(procfd_path, sizeof(procfd_path), "/proc/self/fd/%d",
+                event_fd);
+\&
+        /* Retrieve and print the path of the modified dentry. */
+\&
+        path_len = readlink(procfd_path, path, sizeof(path) \- 1);
+        if (path_len == \-1) {
+            perror("readlink");
+            exit(EXIT_FAILURE);
+        }
+\&
+        path[path_len] = \[aq]\e0\[aq];
+        printf("\etDirectory \[aq]%s\[aq] has been modified.\en", path);
+\&
+        if (file_name) {
+            ret = fstatat(event_fd, file_name, &sb, 0);
+            if (ret == \-1) {
+                if (errno != ENOENT) {
+                    perror("fstatat");
+                    exit(EXIT_FAILURE);
+                }
+                printf("\etEntry \[aq]%s\[aq] does not exist.\en", file_name);
+            } else if ((sb.st_mode & S_IFMT) == S_IFDIR) {
+                printf("\etEntry \[aq]%s\[aq] is a subdirectory.\en", file_name);
+            } else {
+                printf("\etEntry \[aq]%s\[aq] is not a subdirectory.\en",
+                        file_name);
+            }
+        }
+\&
+        /* Close associated file descriptor for this event. */
+\&
+        close(event_fd);
+    }
+\&
+    printf("All events processed successfully. Program exiting.\en");
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.ad l
+.BR fanotify_init (2),
+.BR fanotify_mark (2),
+.BR inotify (7)
diff --git a/man/man7/feature_test_macros.7 b/man/man7/feature_test_macros.7
new file mode 100644
index 000000000..e705445a1
--- /dev/null
+++ b/man/man7/feature_test_macros.7
@@ -0,0 +1,937 @@
+.\" This manpage is Copyright (C) 2006, Michael Kerrisk
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH feature_test_macros 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+feature_test_macros \- feature test macros
+.SH DESCRIPTION
+Feature test macros allow the programmer to control the definitions that
+are exposed by system header files when a program is compiled.
+.P
+.B NOTE:
+In order to be effective, a feature test macro
+.IR "must be defined before including any header files" .
+This can be done either in the compilation command
+.RI ( "cc \-DMACRO=value" )
+or by defining the macro within the source code before
+including any headers.
+The requirement that the macro must be defined before including any
+header file exists because header files may freely include one another.
+Thus, for example, in the following lines, defining the
+.B _GNU_SOURCE
+macro may have no effect because the header
+.I <abc.h>
+itself includes
+.I <xyz.h>
+(POSIX explicitly allows this):
+.P
+.in +4n
+.EX
+#include <abc.h>
+#define _GNU_SOURCE
+#include <xyz.h>
+.EE
+.in
+.P
+Some feature test macros are useful for creating portable applications,
+by preventing nonstandard definitions from being exposed.
+Other macros can be used to expose nonstandard definitions that
+are not exposed by default.
+.P
+The precise effects of each of the feature test macros described below
+can be ascertained by inspecting the
+.I <features.h>
+header file.
+.BR Note :
+applications do
+.I not
+need to directly include
+.IR <features.h> ;
+indeed, doing so is actively discouraged.
+See NOTES.
+.SS Specification of feature test macro requirements in manual pages
+When a function requires that a feature test macro is defined,
+the manual page SYNOPSIS typically includes a note of the following form
+(this example from the
+.BR acct (2)
+manual page):
+.P
+.RS
+.B #include <unistd.h>
+.P
+.BI "int acct(const char *" filename );
+.P
+.RS -4
+.EX
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.EE
+.RE
+.P
+.BR acct ():
+_BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
+.RE
+.P
+The
+.B ||
+means that in order to obtain the declaration of
+.BR acct (2)
+from
+.IR <unistd.h> ,
+.I either
+of the following macro
+definitions must be made before including any header files:
+.P
+.in +4n
+.EX
+#define _BSD_SOURCE
+#define _XOPEN_SOURCE        /* or any value < 500 */
+.EE
+.in
+.P
+Alternatively, equivalent definitions can be included in the
+compilation command:
+.P
+.in +4n
+.EX
+cc \-D_BSD_SOURCE
+cc \-D_XOPEN_SOURCE           # Or any value < 500
+.EE
+.in
+.P
+Note that, as described below,
+.BR "some feature test macros are defined by default" ,
+so that it may not always be necessary to
+explicitly specify the feature test macro(s) shown in the
+SYNOPSIS.
+.P
+In a few cases, manual pages use a shorthand for expressing the
+feature test macro requirements (this example from
+.BR readahead (2)):
+.P
+.RS +4
+.EX
+.B #define _GNU_SOURCE
+.B #define _FILE_OFFSET_BITS 64
+.B #include <fcntl.h>
+.P
+.BI "ssize_t readahead(int " fd ", off_t *" offset ", size_t " count );
+.EE
+.RE
+.P
+This format is employed when the feature test macros ensure
+that the proper function declarations are visible,
+and the macros are not defined by default.
+.SS Feature test macros understood by glibc
+The paragraphs below explain how feature test macros are handled
+in glibc 2.\fIx\fP,
+.I x
+> 0.
+.P
+First, though, a summary of a few details for the impatient:
+.IP \[bu] 3
+The macros that you most likely need to use in modern source code are
+.B _POSIX_C_SOURCE
+(for definitions from various versions of POSIX.1),
+.B _XOPEN_SOURCE
+(for definitions from various versions of SUS),
+.B _GNU_SOURCE
+(for GNU and/or Linux specific stuff), and
+.B _DEFAULT_SOURCE
+(to get definitions that would normally be provided by default).
+.IP \[bu]
+Certain macros are defined with default values.
+Thus, although one or more macros may be indicated as being
+required in the SYNOPSIS of a man page,
+it may not be necessary to define them explicitly.
+Full details of the defaults are given later in this man page.
+.IP \[bu]
+Defining
+.B _XOPEN_SOURCE
+with a value of 600 or greater produces the same effects as defining
+.B _POSIX_C_SOURCE
+with a value of 200112L or greater.
+Where one sees
+.IP
+.in +4n
+.EX
+_POSIX_C_SOURCE >= 200112L
+.EE
+.in
+.IP
+in the feature test macro requirements in the SYNOPSIS of a man page,
+it is implicit that the following has the same effect:
+.IP
+.in +4n
+.EX
+_XOPEN_SOURCE >= 600
+.EE
+.in
+.IP \[bu]
+Defining
+.B _XOPEN_SOURCE
+with a value of 700 or greater produces the same effects as defining
+.B _POSIX_C_SOURCE
+with a value of 200809L or greater.
+Where one sees
+.IP
+.in +4n
+.EX
+_POSIX_C_SOURCE >= 200809L
+.EE
+.in
+.IP
+in the feature test macro requirements in the SYNOPSIS of a man page,
+it is implicit that the following has the same effect:
+.IP
+.in +4n
+.EX
+_XOPEN_SOURCE >= 700
+.EE
+.in
+.\" The details in glibc 2.0 are simpler, but combining a
+.\" a description of them with the details in later glibc versions
+.\" would make for a complicated description.
+.P
+glibc understands the following feature test macros:
+.TP
+.B __STRICT_ANSI__
+ISO Standard C.
+This macro is implicitly defined by
+.BR gcc (1)
+when invoked with, for example, the
+.I \-std=c99
+or
+.I \-ansi
+flag.
+.TP
+.B _POSIX_C_SOURCE
+Defining this macro causes header files to expose definitions as follows:
+.RS
+.IP \[bu] 3
+The value 1 exposes definitions conforming to POSIX.1-1990 and
+ISO C (1990).
+.IP \[bu]
+The value 2 or greater additionally exposes
+definitions for POSIX.2-1992.
+.IP \[bu]
+The value 199309L or greater additionally exposes
+definitions for POSIX.1b (real-time extensions).
+.\" 199506L functionality is available only since glibc 2.1
+.IP \[bu]
+The value 199506L or greater additionally exposes
+definitions for POSIX.1c (threads).
+.IP \[bu]
+(Since glibc 2.3.3)
+The value 200112L or greater additionally exposes definitions corresponding
+to the POSIX.1-2001 base specification (excluding the XSI extension).
+This value also causes C95 (since glibc 2.12) and
+C99 (since glibc 2.10) features to be exposed
+(in other words, the equivalent of defining
+.BR _ISOC99_SOURCE ).
+.IP \[bu]
+(Since glibc 2.10)
+The value 200809L or greater additionally exposes definitions corresponding
+to the POSIX.1-2008 base specification (excluding the XSI extension).
+.RE
+.TP
+.B _POSIX_SOURCE
+Defining this obsolete macro with any value is equivalent to defining
+.B _POSIX_C_SOURCE
+with the value 1.
+.IP
+Since this macro is obsolete,
+its usage is generally not documented when discussing
+feature test macro requirements in the man pages.
+.TP
+.B _XOPEN_SOURCE
+Defining this macro causes header files to expose definitions as follows:
+.RS
+.IP \[bu] 3
+Defining with any value exposes
+definitions conforming to POSIX.1, POSIX.2, and XPG4.
+.IP \[bu]
+The value 500 or greater additionally exposes
+definitions for SUSv2 (UNIX 98).
+.IP \[bu]
+(Since glibc 2.2) The value 600 or greater additionally exposes
+definitions for SUSv3 (UNIX 03; i.e., the POSIX.1-2001 base specification
+plus the XSI extension) and C99 definitions.
+.IP \[bu]
+(Since glibc 2.10) The value 700 or greater additionally exposes
+definitions for SUSv4 (i.e., the POSIX.1-2008 base specification
+plus the XSI extension).
+.RE
+.IP
+If
+.B __STRICT_ANSI__
+is not defined, or
+.B _XOPEN_SOURCE
+is defined with a value greater than or equal to 500
+.I and
+neither
+.B _POSIX_SOURCE
+nor
+.B _POSIX_C_SOURCE
+is explicitly defined, then
+the following macros are implicitly defined:
+.RS
+.IP \[bu] 3
+.B _POSIX_SOURCE
+is defined with the value 1.
+.IP \[bu]
+.B _POSIX_C_SOURCE
+is defined, according to the value of
+.BR _XOPEN_SOURCE :
+.RS
+.TP
+.BR _XOPEN_SOURCE " < 500"
+.B _POSIX_C_SOURCE
+is defined with the value 2.
+.TP
+.RB "500 <= " _XOPEN_SOURCE " < 600"
+.B _POSIX_C_SOURCE
+is defined with the value 199506L.
+.TP
+.RB "600 <= " _XOPEN_SOURCE " < 700"
+.B _POSIX_C_SOURCE
+is defined with the value 200112L.
+.TP
+.RB "700 <= " _XOPEN_SOURCE " (since glibc 2.10)"
+.B _POSIX_C_SOURCE
+is defined with the value 200809L.
+.RE
+.RE
+.IP
+In addition, defining
+.B _XOPEN_SOURCE
+with a value of 500 or greater produces the same effects as defining
+.BR _XOPEN_SOURCE_EXTENDED .
+.TP
+.B _XOPEN_SOURCE_EXTENDED
+If this macro is defined,
+.I and
+.B _XOPEN_SOURCE
+is defined, then expose definitions corresponding to the XPG4v2
+(SUSv1) UNIX extensions (UNIX 95).
+Defining
+.B _XOPEN_SOURCE
+with a value of 500 or more also produces the same effect as defining
+.BR _XOPEN_SOURCE_EXTENDED .
+Use of
+.B _XOPEN_SOURCE_EXTENDED
+in new source code should be avoided.
+.IP
+Since defining
+.B _XOPEN_SOURCE
+with a value of 500 or more has the same effect as defining
+.BR _XOPEN_SOURCE_EXTENDED ,
+the latter (obsolete) feature test macro is generally not described in the
+SYNOPSIS in man pages.
+.TP
+.BR _ISOC99_SOURCE " (since glibc 2.1.3)"
+Exposes declarations consistent with the ISO C99 standard.
+.IP
+Earlier glibc 2.1.x versions recognized an equivalent macro named
+.B _ISOC9X_SOURCE
+(because the C99 standard had not then been finalized).
+Although the use of this macro is obsolete, glibc continues
+to recognize it for backward compatibility.
+.IP
+Defining
+.B _ISOC99_SOURCE
+also exposes ISO C (1990) Amendment 1 ("C95") definitions.
+(The primary change in C95 was support for international character sets.)
+.IP
+Invoking the C compiler with the option
+.I \-std=c99
+produces the same effects as defining this macro.
+.TP
+.BR _ISOC11_SOURCE " (since glibc 2.16)"
+Exposes declarations consistent with the ISO C11 standard.
+Defining this macro also enables C99 and C95 features (like
+.BR _ISOC99_SOURCE ).
+.IP
+Invoking the C compiler with the option
+.I \-std=c11
+produces the same effects as defining this macro.
+.TP
+.B _LARGEFILE64_SOURCE
+Expose definitions for the alternative API specified by the
+LFS (Large File Summit) as a "transitional extension" to the
+Single UNIX Specification.
+(See
+.UR http:\:/\:/opengroup.org\:/platform\:/lfs.html
+.UE .)
+The alternative API consists of a set of new objects
+(i.e., functions and types) whose names are suffixed with "64"
+(e.g.,
+.I off64_t
+versus
+.IR off_t ,
+.BR lseek64 ()
+versus
+.BR lseek (),
+etc.).
+New programs should not employ this macro; instead
+.I _FILE_OFFSET_BITS=64
+should be employed.
+.TP
+.B _LARGEFILE_SOURCE
+This macro was historically used to expose certain functions (specifically
+.BR fseeko (3)
+and
+.BR ftello (3))
+that address limitations of earlier APIs
+.RB ( fseek (3)
+and
+.BR ftell (3))
+that use
+.I long
+for file offsets.
+This macro is implicitly defined if
+.B _XOPEN_SOURCE
+is defined with a value greater than or equal to 500.
+New programs should not employ this macro;
+defining
+.B _XOPEN_SOURCE
+as just described or defining
+.B _FILE_OFFSET_BITS
+with the value 64 is the preferred mechanism to achieve the same result.
+.TP
+.B _FILE_OFFSET_BITS
+Defining this macro with the value 64
+automatically converts references to 32-bit functions and data types
+related to file I/O and filesystem operations into references to
+their 64-bit counterparts.
+This is useful for performing I/O on large files (> 2 Gigabytes)
+on 32-bit systems.
+It is also useful when calling functions like
+.BR copy_file_range (2)
+that were added more recently and that come only in 64-bit flavors.
+(Defining this macro permits correctly written programs to use
+large files with only a recompilation being required.)
+.IP
+64-bit systems naturally permit file sizes greater than 2 Gigabytes,
+and on those systems this macro has no effect.
+.TP
+.B _TIME_BITS
+Defining this macro with the value 64
+changes the width of
+.BR time_t (3type)
+to 64-bit which allows handling of timestamps beyond
+2038.
+It is closely related to
+.B _FILE_OFFSET_BITS
+and depending on implementation, may require it set.
+This macro is available as of glibc 2.34.
+.TP
+.BR _BSD_SOURCE " (deprecated since glibc 2.20)"
+Defining this macro with any value causes header files to expose
+BSD-derived definitions.
+.IP
+In glibc versions up to and including 2.18,
+defining this macro also causes BSD definitions to be preferred in
+some situations where standards conflict, unless one or more of
+.BR _SVID_SOURCE ,
+.BR _POSIX_SOURCE ,
+.BR _POSIX_C_SOURCE ,
+.BR _XOPEN_SOURCE ,
+.BR _XOPEN_SOURCE_EXTENDED ,
+or
+.B _GNU_SOURCE
+is defined, in which case BSD definitions are disfavored.
+Since glibc 2.19,
+.B _BSD_SOURCE
+no longer causes BSD definitions to be preferred in case of conflicts.
+.IP
+Since glibc 2.20, this macro is deprecated.
+.\" commit c941736c92fa3a319221f65f6755659b2a5e0a20
+.\" commit 498afc54dfee41d33ba519f496e96480badace8e
+.\" commit acd7f096d79c181866d56d4aaf3b043e741f1e2c
+It now has the same effect as defining
+.BR _DEFAULT_SOURCE ,
+but generates a compile-time warning (unless
+.B _DEFAULT_SOURCE
+.\" commit ade40b10ff5fa59a318cf55b9d8414b758e8df78
+is also defined).
+Use
+.B _DEFAULT_SOURCE
+instead.
+To allow code that requires
+.B _BSD_SOURCE
+in glibc 2.19 and earlier and
+.B _DEFAULT_SOURCE
+in glibc 2.20 and later to compile without warnings, define
+.I both
+.B _BSD_SOURCE
+and
+.BR _DEFAULT_SOURCE .
+.TP
+.BR _SVID_SOURCE " (deprecated since glibc 2.20)"
+Defining this macro with any value causes header files to expose
+System V-derived definitions.
+(SVID == System V Interface Definition; see
+.BR standards (7).)
+.IP
+Since glibc 2.20, this macro is deprecated in the same fashion as
+.BR _BSD_SOURCE .
+.TP
+.BR _DEFAULT_SOURCE " (since glibc 2.19)"
+This macro can be defined to ensure that the "default"
+definitions are provided even when the defaults would otherwise
+be disabled,
+as happens when individual macros are explicitly defined,
+or the compiler is invoked in one of its "standard" modes (e.g.,
+.IR cc\~\-std=c99 ).
+Defining
+.B _DEFAULT_SOURCE
+without defining other individual macros
+or invoking the compiler in one of its "standard" modes has no effect.
+.IP
+The "default" definitions comprise those required by POSIX.1-2008 and ISO C99,
+as well as various definitions originally derived from BSD and System V.
+On glibc 2.19 and earlier, these defaults were approximately equivalent
+to explicitly defining the following:
+.IP
+.in +4n
+.EX
+cc \-D_BSD_SOURCE \-D_SVID_SOURCE \-D_POSIX_C_SOURCE=200809
+.EE
+.in
+.TP
+.BR _ATFILE_SOURCE " (since glibc 2.4)"
+Defining this macro with any value causes header files to expose
+declarations of a range of functions with the suffix "at";
+see
+.BR openat (2).
+Since glibc 2.10, this macro is also implicitly defined if
+.B _POSIX_C_SOURCE
+is defined with a value greater than or equal to 200809L.
+.TP
+.B _GNU_SOURCE
+Defining this macro (with any value) implicitly defines
+.BR _ATFILE_SOURCE ,
+.BR _LARGEFILE64_SOURCE ,
+.BR _ISOC99_SOURCE ,
+.BR _XOPEN_SOURCE_EXTENDED ,
+.BR _POSIX_SOURCE ,
+.B _POSIX_C_SOURCE
+with the value 200809L
+(200112L before glibc 2.10;
+199506L before glibc 2.5;
+199309L before glibc 2.1)
+and
+.B _XOPEN_SOURCE
+with the value 700
+(600 before glibc 2.10;
+500 before glibc 2.2).
+In addition, various GNU-specific extensions are also exposed.
+.IP
+Since glibc 2.19, defining
+.B _GNU_SOURCE
+also has the effect of implicitly defining
+.BR _DEFAULT_SOURCE .
+Before glibc 2.20, defining
+.B _GNU_SOURCE
+also had the effect of implicitly defining
+.B _BSD_SOURCE
+and
+.BR _SVID_SOURCE .
+.TP
+.B _REENTRANT
+Historically, on various C libraries
+it was necessary to define this macro in all
+multithreaded code.
+.\" Zack Weinberg
+.\"     There did once exist C libraries where it was necessary. The ones
+.\"     I remember were proprietary Unix vendor libcs from the mid-1990s
+.\"     You would get completely unlocked stdio without _REENTRANT.
+(Some C libraries may still require this.)
+In glibc,
+this macro also exposed definitions of certain reentrant functions.
+.IP
+However, glibc has been thread-safe by default for many years;
+since glibc 2.3, the only effect of defining
+.B _REENTRANT
+has been to enable one or two of the same declarations that
+are also enabled by defining
+.B _POSIX_C_SOURCE
+with a value of 199606L or greater.
+.IP
+.B _REENTRANT
+is now obsolete.
+In glibc 2.25 and later, defining
+.B _REENTRANT
+is equivalent to defining
+.B _POSIX_C_SOURCE
+with the value 199606L.
+If a higher POSIX conformance level is
+selected by any other means (such as
+.B _POSIX_C_SOURCE
+itself,
+.BR _XOPEN_SOURCE ,
+.BR _DEFAULT_SOURCE ,
+or
+.BR _GNU_SOURCE ),
+then defining
+.B _REENTRANT
+has no effect.
+.IP
+This macro is automatically defined if one compiles with
+.IR cc\~\-pthread .
+.TP
+.B _THREAD_SAFE
+Synonym for the (deprecated)
+.BR _REENTRANT ,
+provided for compatibility with some other implementations.
+.TP
+.BR _FORTIFY_SOURCE " (since glibc 2.3.4)"
+.\" For more detail, see:
+.\" http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
+.\" [PATCH] Object size checking to prevent (some) buffer overflows
+.\" * From: Jakub Jelinek <jakub at redhat dot com>
+.\" * To: gcc-patches at gcc dot gnu dot org
+.\" * Date: Tue, 21 Sep 2004 04:16:40 -0400
+Defining this macro causes some lightweight checks to be performed
+to detect some buffer overflow errors when employing
+various string and memory manipulation functions (for example,
+.BR memcpy (3),
+.BR memset (3),
+.BR stpcpy (3),
+.BR strcpy (3),
+.BR strncpy (3),
+.BR strcat (3),
+.BR strncat (3),
+.BR sprintf (3),
+.BR snprintf (3),
+.BR vsprintf (3),
+.BR vsnprintf (3),
+.BR gets (3),
+and wide character variants thereof).
+For some functions, argument consistency is checked;
+for example, a check is made that
+.BR open (2)
+has been supplied with a
+.I mode
+argument when the specified flags include
+.BR O_CREAT .
+Not all problems are detected, just some common cases.
+.\" Look for __USE_FORTIFY_LEVEL in the header files
+.IP
+If
+.B _FORTIFY_SOURCE
+is set to 1, with compiler optimization level 1
+.RI ( "gcc\ \-O1" )
+and above, checks that shouldn't change the behavior of
+conforming programs are performed.
+With
+.B _FORTIFY_SOURCE
+set to 2, some more checking is added, but
+some conforming programs might fail.
+.\" For example, given the following code
+.\"        int d;
+.\"        char buf[1000], buf[1000];
+.\"        strcpy(fmt, "Hello world\n%n");
+.\"        snprintf(buf, sizeof(buf), fmt, &d);
+.\"
+.\" Compiling with "gcc -D_FORTIFY_SOURCE=2 -O1" and then running will
+.\" cause the following diagnostic at run time at the snprintf() call
+.\"
+.\"        *** %n in writable segment detected ***
+.\"        Aborted (core dumped)
+.\"
+.IP
+Some of the checks can be performed at compile time
+(via macros logic implemented in header files),
+and result in compiler warnings;
+other checks take place at run time,
+and result in a run-time error if the check fails.
+.IP
+With
+.B _FORTIFY_SOURCE
+set to 3, additional checking is added to intercept
+some function calls used with an argument of variable size
+where the compiler can deduce an upper bound for its value.
+For example, a program where
+.BR malloc (3)'s
+size argument is variable
+can now be fortified.
+.IP
+Use of this macro requires compiler support, available since
+gcc 4.0 and clang 2.6.
+Use of
+.B _FORTIFY_SOURCE
+set to 3 requires gcc 12.0 or later, or clang 9.0 or later,
+in conjunction with glibc 2.33 or later.
+.\" glibc is not an absolute requirement (gcc has libssp; NetBSD/newlib
+.\" and Darwin each have their own implementation), but let's keep it
+.\" simple.
+.SS Default definitions, implicit definitions, and combining definitions
+If no feature test macros are explicitly defined,
+then the following feature test macros are defined by default:
+.B _BSD_SOURCE
+(in glibc 2.19 and earlier),
+.B _SVID_SOURCE
+(in glibc 2.19 and earlier),
+.B _DEFAULT_SOURCE
+(since glibc 2.19),
+.BR _POSIX_SOURCE ,
+and
+.BR _POSIX_C_SOURCE =200809L
+(200112L before glibc 2.10;
+199506L before glibc 2.4;
+199309L before glibc 2.1).
+.P
+If any of
+.BR __STRICT_ANSI__ ,
+.BR _ISOC99_SOURCE ,
+.B _ISOC11_SOURCE
+(since glibc 2.18),
+.BR _POSIX_SOURCE ,
+.BR _POSIX_C_SOURCE  ,
+.BR _XOPEN_SOURCE ,
+.B _XOPEN_SOURCE_EXTENDED
+(in glibc 2.11 and earlier),
+.B _BSD_SOURCE
+(in glibc 2.19 and earlier),
+or
+.B _SVID_SOURCE
+(in glibc 2.19 and earlier)
+is explicitly defined, then
+.BR _BSD_SOURCE ,
+.BR _SVID_SOURCE ,
+and
+.B _DEFAULT_SOURCE
+are not defined by default.
+.P
+If
+.B _POSIX_SOURCE
+and
+.B _POSIX_C_SOURCE
+are not explicitly defined,
+and either
+.B __STRICT_ANSI__
+is not defined or
+.B _XOPEN_SOURCE
+is defined with a value of 500 or more, then
+.IP \[bu] 3
+.B _POSIX_SOURCE
+is defined with the value 1; and
+.IP \[bu]
+.B _POSIX_C_SOURCE
+is defined with one of the following values:
+.RS
+.IP \[bu] 3
+2,
+if
+.B _XOPEN_SOURCE
+is defined with a value less than 500;
+.IP \[bu]
+199506L,
+if
+.B _XOPEN_SOURCE
+is defined with a value greater than or equal to 500 and less than 600;
+or
+.IP \[bu]
+(since glibc 2.4) 200112L,
+if
+.B _XOPEN_SOURCE
+is defined with a value greater than or equal to 600 and less than 700.
+.IP \[bu]
+(Since glibc 2.10)
+200809L,
+if
+.B _XOPEN_SOURCE
+is defined with a value greater than or equal to 700.
+.IP \[bu]
+Older versions of glibc do not know about the values
+200112L and 200809L for
+.BR _POSIX_C_SOURCE ,
+and the setting of this macro will depend on the glibc version.
+.IP \[bu]
+If
+.B _XOPEN_SOURCE
+is undefined, then the setting of
+.B _POSIX_C_SOURCE
+depends on the glibc version:
+199506L, before glibc 2.4;
+200112L, since glibc 2.4 to glibc 2.9; and
+200809L, since glibc 2.10.
+.RE
+.P
+Multiple macros can be defined; the results are additive.
+.SH STANDARDS
+POSIX.1 specifies
+.BR _POSIX_C_SOURCE ,
+.BR _POSIX_SOURCE ,
+and
+.BR _XOPEN_SOURCE .
+.P
+.B _FILE_OFFSET_BITS
+is not specified by any standard,
+but is employed on some other implementations.
+.P
+.BR _BSD_SOURCE ,
+.BR _SVID_SOURCE ,
+.BR _DEFAULT_SOURCE ,
+.BR _ATFILE_SOURCE ,
+.BR _GNU_SOURCE ,
+.BR _FORTIFY_SOURCE ,
+.BR _REENTRANT ,
+and
+.B _THREAD_SAFE
+are specific to glibc.
+.SH HISTORY
+.B _XOPEN_SOURCE_EXTENDED
+was specified by XPG4v2 (aka SUSv1), but is not present in SUSv2 and later.
+.SH NOTES
+.I <features.h>
+is a Linux/glibc-specific header file.
+Other systems have an analogous file, but typically with a different name.
+This header file is automatically included by other header files as
+required: it is not necessary to explicitly include it in order to
+employ feature test macros.
+.P
+According to which of the above feature test macros are defined,
+.I <features.h>
+internally defines various other macros that are checked by
+other glibc header files.
+These macros have names prefixed by two underscores (e.g.,
+.BR __USE_MISC ).
+Programs should
+.I never
+define these macros directly:
+instead, the appropriate feature test macro(s) from the
+list above should be employed.
+.SH EXAMPLES
+The program below can be used to explore how the various
+feature test macros are set depending on the glibc version
+and what feature test macros are explicitly set.
+The following shell session, on a system with glibc 2.10,
+shows some examples of what we would see:
+.P
+.in +4n
+.EX
+$ \fBcc ftm.c\fP
+$ \fB./a.out\fP
+_POSIX_SOURCE defined
+_POSIX_C_SOURCE defined: 200809L
+_BSD_SOURCE defined
+_SVID_SOURCE defined
+_ATFILE_SOURCE defined
+$ \fBcc \-D_XOPEN_SOURCE=500 ftm.c\fP
+$ \fB./a.out\fP
+_POSIX_SOURCE defined
+_POSIX_C_SOURCE defined: 199506L
+_XOPEN_SOURCE defined: 500
+$ \fBcc \-D_GNU_SOURCE ftm.c\fP
+$ \fB./a.out\fP
+_POSIX_SOURCE defined
+_POSIX_C_SOURCE defined: 200809L
+_ISOC99_SOURCE defined
+_XOPEN_SOURCE defined: 700
+_XOPEN_SOURCE_EXTENDED defined
+_LARGEFILE64_SOURCE defined
+_BSD_SOURCE defined
+_SVID_SOURCE defined
+_ATFILE_SOURCE defined
+_GNU_SOURCE defined
+.EE
+.in
+.SS Program source
+\&
+.EX
+/* ftm.c */
+\&
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+\&
+int
+main(int argc, char *argv[])
+{
+#ifdef _POSIX_SOURCE
+    printf("_POSIX_SOURCE defined\en");
+#endif
+\&
+#ifdef _POSIX_C_SOURCE
+    printf("_POSIX_C_SOURCE defined: %jdL\en",
+            (intmax_t) _POSIX_C_SOURCE);
+#endif
+\&
+#ifdef _ISOC99_SOURCE
+    printf("_ISOC99_SOURCE defined\en");
+#endif
+\&
+#ifdef _ISOC11_SOURCE
+    printf("_ISOC11_SOURCE defined\en");
+#endif
+\&
+#ifdef _XOPEN_SOURCE
+    printf("_XOPEN_SOURCE defined: %d\en", _XOPEN_SOURCE);
+#endif
+\&
+#ifdef _XOPEN_SOURCE_EXTENDED
+    printf("_XOPEN_SOURCE_EXTENDED defined\en");
+#endif
+\&
+#ifdef _LARGEFILE64_SOURCE
+    printf("_LARGEFILE64_SOURCE defined\en");
+#endif
+\&
+#ifdef _FILE_OFFSET_BITS
+    printf("_FILE_OFFSET_BITS defined: %d\en", _FILE_OFFSET_BITS);
+#endif
+\&
+#ifdef _TIME_BITS
+    printf("_TIME_BITS defined: %d\en", _TIME_BITS);
+#endif
+\&
+#ifdef _BSD_SOURCE
+    printf("_BSD_SOURCE defined\en");
+#endif
+\&
+#ifdef _SVID_SOURCE
+    printf("_SVID_SOURCE defined\en");
+#endif
+\&
+#ifdef _DEFAULT_SOURCE
+    printf("_DEFAULT_SOURCE defined\en");
+#endif
+\&
+#ifdef _ATFILE_SOURCE
+    printf("_ATFILE_SOURCE defined\en");
+#endif
+\&
+#ifdef _GNU_SOURCE
+    printf("_GNU_SOURCE defined\en");
+#endif
+\&
+#ifdef _REENTRANT
+    printf("_REENTRANT defined\en");
+#endif
+\&
+#ifdef _THREAD_SAFE
+    printf("_THREAD_SAFE defined\en");
+#endif
+\&
+#ifdef _FORTIFY_SOURCE
+    printf("_FORTIFY_SOURCE defined\en");
+#endif
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR libc (7),
+.BR standards (7),
+.BR system_data_types (7)
+.P
+The section "Feature Test Macros" under
+.IR "info libc" .
+.\" But beware: the info libc document is out of date (Jul 07, mtk)
+.P
+.I /usr/include/features.h
diff --git a/man/man7/fifo.7 b/man/man7/fifo.7
new file mode 100644
index 000000000..92ac5fd89
--- /dev/null
+++ b/man/man7/fifo.7
@@ -0,0 +1,70 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Claus Fischer.
+.\"
+.\" 990620 - page created - aeb@cwi.nl
+.\"
+.TH fifo 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+fifo \- first-in first-out special file, named pipe
+.SH DESCRIPTION
+A FIFO special file (a named pipe) is similar to a pipe,
+except that it is accessed as part of the filesystem.
+It can be opened by multiple processes for reading or
+writing.
+When processes are exchanging data via the FIFO,
+the kernel passes all data internally without writing it
+to the filesystem.
+Thus, the FIFO special file has no
+contents on the filesystem; the filesystem entry merely
+serves as a reference point so that processes can access
+the pipe using a name in the filesystem.
+.P
+The kernel maintains exactly one pipe object for each
+FIFO special file that is opened by at least one process.
+The FIFO must be opened on both ends (reading and writing)
+before data can be passed.
+Normally, opening the FIFO blocks
+until the other end is opened also.
+.P
+A process can open a FIFO in nonblocking mode.
+In this
+case, opening for read-only succeeds even if no one has
+opened on the write side yet and opening for write-only
+fails with
+.B ENXIO
+(no such device or address) unless the other
+end has already been opened.
+.P
+Under Linux, opening a FIFO for read and write will succeed
+both in blocking and nonblocking mode.
+POSIX leaves this
+behavior undefined.
+This can be used to open a FIFO for
+writing while there are no readers available.
+A process
+that uses both ends of the connection in order to communicate
+with itself should be very careful to avoid deadlocks.
+.SH NOTES
+For details of the semantics of I/O on FIFOs, see
+.BR pipe (7).
+.P
+When a process tries to write to a FIFO that is not opened
+for read on the other side, the process is sent a
+.B SIGPIPE
+signal.
+.P
+FIFO special files can be created by
+.BR mkfifo (3),
+and are indicated by
+.I ls\~\-l
+with the file type \[aq]p\[aq].
+.SH SEE ALSO
+.BR mkfifo (1),
+.BR open (2),
+.BR pipe (2),
+.BR sigaction (2),
+.BR signal (2),
+.BR socketpair (2),
+.BR mkfifo (3),
+.BR pipe (7)
diff --git a/man/man7/futex.7 b/man/man7/futex.7
new file mode 100644
index 000000000..7a8fcd5a7
--- /dev/null
+++ b/man/man7/futex.7
@@ -0,0 +1,121 @@
+.\" This manpage has been automatically generated by docbook2man
+.\" from a DocBook document.  This tool can be found at:
+.\" <http://shell.ipoline.com/~elmert/comp/docbook2X/>
+.\" Please send any bug reports, improvements, comments, patches,
+.\" etc. to Steve Cheng <steve@ggi-project.org>.
+.\"
+.\" SPDX-License-Identifier: MIT
+.\"
+.TH futex 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+futex \- fast user-space locking
+.SH SYNOPSIS
+.nf
+.B #include <linux/futex.h>
+.fi
+.SH DESCRIPTION
+The Linux kernel provides futexes ("Fast user-space mutexes")
+as a building block for fast user-space
+locking and semaphores.
+Futexes are very basic and lend themselves well for building higher-level
+locking abstractions such as
+mutexes, condition variables, read-write locks, barriers, and semaphores.
+.P
+Most programmers will in fact not be using futexes directly but will
+instead rely on system libraries built on them,
+such as the Native POSIX Thread Library (NPTL) (see
+.BR pthreads (7)).
+.P
+A futex is identified by a piece of memory which can be
+shared between processes or threads.
+In these different processes, the futex need not have identical addresses.
+In its bare form, a futex has semaphore semantics;
+it is a counter that can be incremented and decremented atomically;
+processes can wait for the value to become positive.
+.P
+Futex operation occurs entirely in user space for the noncontended case.
+The kernel is involved only to arbitrate the contended case.
+As any sane design will strive for noncontention,
+futexes are also optimized for this situation.
+.P
+In its bare form, a futex is an aligned integer which is
+touched only by atomic assembler instructions.
+This integer is four bytes long on all platforms.
+Processes can share this integer using
+.BR mmap (2),
+via shared memory segments, or because they share memory space,
+in which case the application is commonly called multithreaded.
+.SS Semantics
+Any futex operation starts in user space,
+but it may be necessary to communicate with the kernel using the
+.BR futex (2)
+system call.
+.P
+To "up" a futex, execute the proper assembler instructions that
+will cause the host CPU to atomically increment the integer.
+Afterward, check if it has in fact changed from 0 to 1, in which case
+there were no waiters and the operation is done.
+This is the noncontended case which is fast and should be common.
+.P
+In the contended case, the atomic increment changed the counter
+from \-1  (or some other negative number).
+If this is detected, there are waiters.
+User space should now set the counter to 1 and instruct the
+kernel to wake up any waiters using the
+.B FUTEX_WAKE
+operation.
+.P
+Waiting on a futex, to "down" it, is the reverse operation.
+Atomically decrement the counter and check if it changed to 0,
+in which case the operation is done and the futex was uncontended.
+In all other circumstances, the process should set the counter to \-1
+and request that the kernel wait for another process to up the futex.
+This is done using the
+.B FUTEX_WAIT
+operation.
+.P
+The
+.BR futex (2)
+system call can optionally be passed a timeout specifying how long
+the kernel should
+wait for the futex to be upped.
+In this case, semantics are more complex and the programmer is referred
+to
+.BR futex (2)
+for
+more details.
+The same holds for asynchronous futex waiting.
+.SH VERSIONS
+Initial futex support was merged in Linux 2.5.7
+but with different semantics from those described above.
+Current semantics are available from Linux 2.5.40 onward.
+.SH NOTES
+To reiterate, bare futexes are not intended as an easy-to-use
+abstraction for end users.
+Implementors are expected to be assembly literate and to have read
+the sources of the futex user-space library referenced
+below.
+.P
+This man page illustrates the most common use of the
+.BR futex (2)
+primitives; it is by no means the only one.
+.\" .SH AUTHORS
+.\" .P
+.\" Futexes were designed and worked on by Hubertus Franke
+.\" (IBM Thomas J. Watson Research Center),
+.\" Matthew Kirkwood, Ingo Molnar (Red Hat) and
+.\" Rusty Russell (IBM Linux Technology Center).
+.\" This page written by bert hubert.
+.SH SEE ALSO
+.BR clone (2),
+.BR futex (2),
+.BR get_robust_list (2),
+.BR set_robust_list (2),
+.BR set_tid_address (2),
+.BR pthreads (7)
+.P
+.I Fuss, Futexes and Furwocks: Fast Userlevel Locking in Linux
+(proceedings of the Ottawa Linux Symposium 2002),
+futex example library, futex-*.tar.bz2
+.UR https://mirrors.kernel.org\:/pub\:/linux\:/kernel\:/people\:/rusty/
+.UE .
diff --git a/man/man7/glibc.7 b/man/man7/glibc.7
new file mode 100644
index 000000000..0d1ed269c
--- /dev/null
+++ b/man/man7/glibc.7
@@ -0,0 +1 @@
+.so man7/libc.7
diff --git a/man/man7/glob.7 b/man/man7/glob.7
new file mode 100644
index 000000000..6217b2c3e
--- /dev/null
+++ b/man/man7/glob.7
@@ -0,0 +1,205 @@
+.\" Copyright (c) 1998 Andries Brouwer
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2003-08-24 fix for / by John Kristoff + joey
+.\"
+.TH glob 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+glob \- globbing pathnames
+.SH DESCRIPTION
+Long ago, in UNIX\ V6, there was a program
+.I /etc/glob
+that would expand wildcard patterns.
+Soon afterward this became a shell built-in.
+.P
+These days there is also a library routine
+.BR glob (3)
+that will perform this function for a user program.
+.P
+The rules are as follows (POSIX.2, 3.13).
+.SS Wildcard matching
+A string is a wildcard pattern if it contains one of the
+characters \[aq]?\[aq], \[aq]*\[aq], or \[aq][\[aq].
+Globbing is the operation
+that expands a wildcard pattern into the list of pathnames
+matching the pattern.
+Matching is defined by:
+.P
+A \[aq]?\[aq] (not between brackets) matches any single character.
+.P
+A \[aq]*\[aq] (not between brackets) matches any string,
+including the empty string.
+.P
+.B "Character classes"
+.P
+An expression "\fI[...]\fP" where the first character after the
+leading \[aq][\[aq] is not an \[aq]!\[aq] matches a single character,
+namely any of the characters enclosed by the brackets.
+The string enclosed by the brackets cannot be empty;
+therefore \[aq]]\[aq] can be allowed between the brackets, provided
+that it is the first character.
+(Thus, "\fI[][!]\fP" matches the
+three characters \[aq][\[aq], \[aq]]\[aq], and \[aq]!\[aq].)
+.P
+.B Ranges
+.P
+There is one special convention:
+two characters separated by \[aq]\-\[aq] denote a range.
+(Thus,
+"\fI[A\-Fa\-f0\-9]\fP" is equivalent to "\fI[ABCDEFabcdef0123456789]\fP".)
+One may include \[aq]\-\[aq] in its literal meaning
+by making it the first or last character between the brackets.
+(Thus,
+"\fI[]\-]\fP" matches just the two characters \[aq]]\[aq] and \[aq]\-\[aq],
+and "\fI[\-\-0]\fP" matches the
+three characters \[aq]\-\[aq], \[aq].\[aq], and \[aq]0\[aq],
+since \[aq]/\[aq] cannot be matched.)
+.P
+.B Complementation
+.P
+An expression "\fI[!...]\fP" matches a single character, namely
+any character that is not matched by the expression obtained
+by removing the first \[aq]!\[aq] from it.
+(Thus, "\fI[!]a\-]\fP" matches any
+single character except \[aq]]\[aq], \[aq]a\[aq], and \[aq]\-\[aq].)
+.P
+One can remove the special meaning of \[aq]?\[aq], \[aq]*\[aq], and \[aq][\[aq]
+by preceding them by a backslash,
+or,
+in case this is part of a shell command line,
+enclosing them in quotes.
+Between brackets these characters stand for themselves.
+Thus, "\fI[[?*\e]\fP" matches the
+four characters \[aq][\[aq], \[aq]?\[aq], \[aq]*\[aq], and \[aq]\e\[aq].
+.SS Pathnames
+Globbing is applied on each of the components of a pathname
+separately.
+A \[aq]/\[aq] in a pathname cannot be matched by a \[aq]?\[aq] or \[aq]*\[aq]
+wildcard, or by a range like "\fI[.\-0]\fP".
+A range containing an explicit \[aq]/\[aq] character is syntactically incorrect.
+(POSIX requires that syntactically incorrect patterns are left unchanged.)
+.P
+If a filename starts with a \[aq].\[aq],
+this character must be matched explicitly.
+(Thus, \fIrm\ *\fP will not remove .profile, and \fItar\ c\ *\fP will not
+archive all your files; \fItar\ c\ .\fP is better.)
+.SS Empty lists
+The nice and simple rule given above: "expand a wildcard pattern
+into the list of matching pathnames" was the original UNIX
+definition.
+It allowed one to have patterns that expand into
+an empty list, as in
+.P
+.nf
+    xv \-wait 0 *.gif *.jpg
+.fi
+.P
+where perhaps no *.gif files are present (and this is not
+an error).
+However, POSIX requires that a wildcard pattern is left
+unchanged when it is syntactically incorrect, or the list of
+matching pathnames is empty.
+With
+.I bash
+one can force the classical behavior using this command:
+.P
+.in +4n
+.EX
+shopt \-s nullglob
+.EE
+.in
+.\" In Bash v1, by setting allow_null_glob_expansion=true
+.P
+(Similar problems occur elsewhere.
+For example, where old scripts have
+.P
+.in +4n
+.EX
+rm \`find . \-name "*\[ti]"\`
+.EE
+.in
+.P
+new scripts require
+.P
+.in +4n
+.EX
+rm \-f nosuchfile \`find . \-name "*\[ti]"\`
+.EE
+.in
+.P
+to avoid error messages from
+.I rm
+called with an empty argument list.)
+.SH NOTES
+.SS Regular expressions
+Note that wildcard patterns are not regular expressions,
+although they are a bit similar.
+First of all, they match
+filenames, rather than text, and secondly, the conventions
+are not the same: for example, in a regular expression \[aq]*\[aq] means zero or
+more copies of the preceding thing.
+.P
+Now that regular expressions have bracket expressions where
+the negation is indicated by a \[aq]\[ha]\[aq], POSIX has declared the
+effect of a wildcard pattern "\fI[\[ha]...]\fP" to be undefined.
+.SS Character classes and internationalization
+Of course ranges were originally meant to be ASCII ranges,
+so that "\fI[\ \-%]\fP" stands for "\fI[\ !"#$%]\fP" and "\fI[a\-z]\fP" stands
+for "any lowercase letter".
+Some UNIX implementations generalized this so that a range X\-Y
+stands for the set of characters with code between the codes for
+X and for Y.
+However, this requires the user to know the
+character coding in use on the local system, and moreover, is
+not convenient if the collating sequence for the local alphabet
+differs from the ordering of the character codes.
+Therefore, POSIX extended the bracket notation greatly,
+both for wildcard patterns and for regular expressions.
+In the above we saw three types of items that can occur in a bracket
+expression: namely (i) the negation, (ii) explicit single characters,
+and (iii) ranges.
+POSIX specifies ranges in an internationally
+more useful way and adds three more types:
+.P
+(iii) Ranges X\-Y comprise all characters that fall between X
+and Y (inclusive) in the current collating sequence as defined
+by the
+.B LC_COLLATE
+category in the current locale.
+.P
+(iv) Named character classes, like
+.P
+.nf
+[:alnum:]  [:alpha:]  [:blank:]  [:cntrl:]
+[:digit:]  [:graph:]  [:lower:]  [:print:]
+[:punct:]  [:space:]  [:upper:]  [:xdigit:]
+.fi
+.P
+so that one can say "\fI[[:lower:]]\fP" instead of "\fI[a\-z]\fP", and have
+things work in Denmark, too, where there are three letters past \[aq]z\[aq]
+in the alphabet.
+These character classes are defined by the
+.B LC_CTYPE
+category
+in the current locale.
+.P
+(v) Collating symbols, like "\fI[.ch.]\fP" or "\fI[.a-acute.]\fP",
+where the string between "\fI[.\fP" and "\fI.]\fP" is a collating
+element defined for the current locale.
+Note that this may
+be a multicharacter element.
+.P
+(vi) Equivalence class expressions, like "\fI[=a=]\fP",
+where the string between "\fI[=\fP" and "\fI=]\fP" is any collating
+element from its equivalence class, as defined for the
+current locale.
+For example, "\fI[[=a=]]\fP" might be equivalent
+to "\fI[a\('a\(`a\(:a\(^a]\fP", that is,
+to "\fI[a[.a-acute.][.a-grave.][.a-umlaut.][.a-circumflex.]]\fP".
+.SH SEE ALSO
+.BR sh (1),
+.BR fnmatch (3),
+.BR glob (3),
+.BR locale (7),
+.BR regex (7)
diff --git a/man/man7/hier.7 b/man/man7/hier.7
new file mode 100644
index 000000000..cdccc1ffa
--- /dev/null
+++ b/man/man7/hier.7
@@ -0,0 +1,654 @@
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sun Jul 25 11:05:58 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sat Feb 10 16:18:03 1996 by Urs Thuermann (urs@isnogud.escape.de)
+.\" Modified Mon Jun 16 20:02:00 1997 by Nicolás Lichtmaier <nick@debian.org>
+.\" Modified Mon Feb  6 16:41:00 1999 by Nicolás Lichtmaier <nick@debian.org>
+.\" Modified Tue Feb  8 16:46:45 2000 by Chris Pepper <pepper@tgg.com>
+.\" Modified Fri Sep  7 20:32:45 2001 by Tammy Fox <tfox@redhat.com>
+.TH hier 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hier \- description of the filesystem hierarchy
+.SH DESCRIPTION
+A typical Linux system has, among others, the following directories:
+.TP
+.I /
+This is the root directory.
+This is where the whole tree starts.
+.TP
+.I /bin
+This directory contains executable programs which are needed in
+single user mode and to bring the system up or repair it.
+.TP
+.I /boot
+Contains static files for the boot loader.
+This directory holds only
+the files which are needed during the boot process.
+The map installer
+and configuration files should go to
+.I /sbin
+and
+.IR /etc .
+The operating system kernel (initrd for example) must be located in either
+.I /
+or
+.IR /boot .
+.TP
+.I /dev
+Special or device files, which refer to physical devices.
+See
+.BR mknod (1).
+.TP
+.I /etc
+Contains configuration files which are local to the machine.
+Some
+larger software packages, like X11, can have their own subdirectories
+below
+.IR /etc .
+Site-wide configuration files may be placed here or in
+.IR /usr/etc .
+Nevertheless, programs should always look for these files in
+.I /etc
+and you may have links for these files to
+.IR /usr/etc .
+.TP
+.I /etc/opt
+Host-specific configuration files for add-on applications installed
+in
+.IR /opt .
+.TP
+.I /etc/sgml
+This directory contains the configuration files for SGML (optional).
+.TP
+.I /etc/skel
+When a new user account is created, files from this directory are
+usually copied into the user's home directory.
+.TP
+.I /etc/X11
+Configuration files for the X11 window system (optional).
+.TP
+.I /etc/xml
+This directory contains the configuration files for XML (optional).
+.TP
+.I /home
+On machines with home directories for users, these are usually beneath
+this directory, directly or not.
+The structure of this directory
+depends on local administration decisions (optional).
+.TP
+.I /lib
+This directory should hold those shared libraries that are necessary
+to boot the system and to run the commands in the root filesystem.
+.TP
+.I /lib<qual>
+These directories are variants of
+.I /lib
+on system which support more than one binary format requiring separate
+libraries (optional).
+.TP
+.I /lib/modules
+Loadable kernel modules (optional).
+.TP
+.I /lost+found
+This directory contains items lost in the filesystem.
+These items are usually chunks of files mangled as a consequence of
+a faulty disk or a system crash.
+.TP
+.I /media
+This directory contains mount points for removable media such as CD
+and DVD disks or USB sticks.
+On systems where more than one device exists
+for mounting a certain type of media,
+mount directories can be created by appending a digit
+to the name of those available above starting with '0',
+but the unqualified name must also exist.
+.TP
+.I /media/floppy[1\-9]
+Floppy drive (optional).
+.TP
+.I /media/cdrom[1\-9]
+CD-ROM drive (optional).
+.TP
+.I /media/cdrecorder[1\-9]
+CD writer (optional).
+.TP
+.I /media/zip[1\-9]
+Zip drive (optional).
+.TP
+.I /media/usb[1\-9]
+USB drive (optional).
+.TP
+.I /mnt
+This directory is a mount point for a temporarily mounted filesystem.
+In some distributions,
+.I /mnt
+contains subdirectories intended to be used as mount points for several
+temporary filesystems.
+.TP
+.I /opt
+This directory should contain add-on packages that contain static files.
+.TP
+.I /proc
+This is a mount point for the
+.I proc
+filesystem, which provides information about running processes and
+the kernel.
+This pseudo-filesystem is described in more detail in
+.BR proc (5).
+.TP
+.I /root
+This directory is usually the home directory for the root user (optional).
+.TP
+.I /run
+This directory contains information which
+describes the system since it was booted.
+Once this purpose was served by
+.I /var/run
+and programs may continue to use it.
+.TP
+.I /sbin
+Like
+.IR /bin ,
+this directory holds commands needed to boot the system, but which are
+usually not executed by normal users.
+.TP
+.I /srv
+This directory contains site-specific data that is served by this system.
+.TP
+.I /sys
+This is a mount point for the sysfs filesystem, which provides information
+about the kernel like
+.IR /proc ,
+but better structured, following the formalism of kobject infrastructure.
+.TP
+.I /tmp
+This directory contains temporary files which may be deleted with no
+notice, such as by a regular job or at system boot up.
+.TP
+.I /usr
+This directory is usually mounted from a separate partition.
+It should hold only shareable, read-only data, so that it can be mounted
+by various machines running Linux.
+.TP
+.I /usr/X11R6
+The X\-Window system, version 11 release 6 (present in FHS 2.3, removed
+in FHS 3.0).
+.TP
+.I /usr/X11R6/bin
+Binaries which belong to the X\-Window system; often, there is a
+symbolic link from the more traditional
+.I /usr/bin/X11
+to here.
+.TP
+.I /usr/X11R6/lib
+Data files associated with the X\-Window system.
+.TP
+.I /usr/X11R6/lib/X11
+These contain miscellaneous files needed to run X;  Often, there is a
+symbolic link from
+.I /usr/lib/X11
+to this directory.
+.TP
+.I /usr/X11R6/include/X11
+Contains include files needed for compiling programs using the X11
+window system.
+Often, there is a symbolic link from
+.I /usr/include/X11
+to this directory.
+.TP
+.I /usr/bin
+This is the primary directory for executable programs.
+Most programs
+executed by normal users which are not needed for booting or for
+repairing the system and which are not installed locally should be
+placed in this directory.
+.TP
+.I /usr/bin/mh
+Commands for the MH mail handling system (optional).
+.TP
+.I /usr/bin/X11
+This is the traditional place to look for X11 executables; on Linux, it
+usually is a symbolic link to
+.IR /usr/X11R6/bin .
+.TP
+.I /usr/dict
+Replaced by
+.IR /usr/share/dict .
+.TP
+.I /usr/doc
+Replaced by
+.IR /usr/share/doc .
+.TP
+.I /usr/etc
+Site-wide configuration files to be shared between several machines
+may be stored in this directory.
+However, commands should always
+reference those files using the
+.I /etc
+directory.
+Links from files in
+.I /etc
+should point to the appropriate files in
+.IR /usr/etc .
+.TP
+.I /usr/games
+Binaries for games and educational programs (optional).
+.TP
+.I /usr/include
+Include files for the C compiler.
+.TP
+.I /usr/include/bsd
+BSD compatibility include files (optional).
+.TP
+.I /usr/include/X11
+Include files for the C compiler and the X\-Window system.
+This is
+usually a symbolic link to
+.IR /usr/X11R6/include/X11 .
+.TP
+.I /usr/include/asm
+Include files which declare some assembler functions.
+This used to be a
+symbolic link to
+.IR /usr/src/linux/include/asm .
+.TP
+.I /usr/include/linux
+This contains information which may change from system release to
+system release and used to be a symbolic link to
+.I /usr/src/linux/include/linux
+to get at operating-system-specific information.
+.IP
+(Note that one should have include files there that work correctly with
+the current libc and in user space.
+However, Linux kernel source is not
+designed to be used with user programs and does not know anything
+about the libc you are using.
+It is very likely that things will break
+if you let
+.I /usr/include/asm
+and
+.I /usr/include/linux
+point at a random kernel tree.
+Debian systems don't do this
+and use headers from a known good kernel
+version, provided in the libc*\-dev package.)
+.TP
+.I /usr/include/g++
+Include files to use with the GNU C++ compiler.
+.TP
+.I /usr/lib
+Object libraries, including dynamic libraries, plus some executables
+which usually are not invoked directly.
+More complicated programs may
+have whole subdirectories there.
+.TP
+.I /usr/libexec
+Directory contains binaries for internal use only and they are not meant
+to be executed directly by users shell or scripts.
+.TP
+.I /usr/lib<qual>
+These directories are variants of
+.I /usr/lib
+on system which support more than one binary format requiring separate
+libraries, except that the symbolic link
+.IR /usr/lib qual /X11
+is not required (optional).
+.TP
+.I /usr/lib/X11
+The usual place for data files associated with X programs, and
+configuration files for the X system itself.
+On Linux, it usually is
+a symbolic link to
+.IR /usr/X11R6/lib/X11 .
+.TP
+.I /usr/lib/gcc\-lib
+contains executables and include files for the GNU C compiler,
+.BR gcc (1).
+.TP
+.I /usr/lib/groff
+Files for the GNU groff document formatting system.
+.TP
+.I /usr/lib/uucp
+Files for
+.BR uucp (1).
+.TP
+.I /usr/local
+This is where programs which are local to the site typically go.
+.TP
+.I /usr/local/bin
+Binaries for programs local to the site.
+.TP
+.I /usr/local/doc
+Local documentation.
+.TP
+.I /usr/local/etc
+Configuration files associated with locally installed programs.
+.TP
+.I /usr/local/games
+Binaries for locally installed games.
+.TP
+.I /usr/local/lib
+Files associated with locally installed programs.
+.TP
+.I /usr/local/lib<qual>
+These directories are variants of
+.I /usr/local/lib
+on system which support more than one binary format requiring separate
+libraries (optional).
+.TP
+.I /usr/local/include
+Header files for the local C compiler.
+.TP
+.I /usr/local/info
+Info pages associated with locally installed programs.
+.TP
+.I /usr/local/man
+Man pages associated with locally installed programs.
+.TP
+.I /usr/local/sbin
+Locally installed programs for system administration.
+.TP
+.I /usr/local/share
+Local application data that can be shared among different architectures
+of the same OS.
+.TP
+.I /usr/local/src
+Source code for locally installed software.
+.TP
+.I /usr/man
+Replaced by
+.IR /usr/share/man .
+.TP
+.I /usr/sbin
+This directory contains program binaries for system administration
+which are not essential for the boot process, for mounting
+.IR /usr ,
+or for system repair.
+.TP
+.I /usr/share
+This directory contains subdirectories with specific application data, that
+can be shared among different architectures of the same OS.
+Often one finds stuff here that used to live in
+.I /usr/doc
+or
+.I /usr/lib
+or
+.IR /usr/man .
+.TP
+.I /usr/share/color
+Contains color management information, like International Color Consortium (ICC)
+Color profiles (optional).
+.TP
+.I /usr/share/dict
+Contains the word lists used by spell checkers (optional).
+.TP
+.I /usr/share/dict/words
+List of English words (optional).
+.TP
+.I /usr/share/doc
+Documentation about installed programs (optional).
+.TP
+.I /usr/share/games
+Static data files for games in
+.I /usr/games
+(optional).
+.TP
+.I /usr/share/info
+Info pages go here (optional).
+.TP
+.I /usr/share/locale
+Locale information goes here (optional).
+.TP
+.I /usr/share/man
+Manual pages go here in subdirectories according to the man page sections.
+.TP
+.IR /usr/share/man/ locale /man[1\-9]
+These directories contain manual pages for the
+specific locale in source code form.
+Systems which use a unique language and code set for all manual pages
+may omit the <locale> substring.
+.TP
+.I /usr/share/misc
+Miscellaneous data that can be shared among different architectures of the
+same OS.
+.TP
+.I /usr/share/nls
+The message catalogs for native language support go here (optional).
+.TP
+.I /usr/share/ppd
+Postscript Printer Definition (PPD) files (optional).
+.TP
+.I /usr/share/sgml
+Files for SGML (optional).
+.TP
+.I /usr/share/sgml/docbook
+DocBook DTD (optional).
+.TP
+.I /usr/share/sgml/tei
+TEI DTD (optional).
+.TP
+.I /usr/share/sgml/html
+HTML DTD (optional).
+.TP
+.I /usr/share/sgml/mathml
+MathML DTD (optional).
+.TP
+.I /usr/share/terminfo
+The database for terminfo (optional).
+.TP
+.I /usr/share/tmac
+Troff macros that are not distributed with groff (optional).
+.TP
+.I /usr/share/xml
+Files for XML (optional).
+.TP
+.I /usr/share/xml/docbook
+DocBook DTD (optional).
+.TP
+.I /usr/share/xml/xhtml
+XHTML DTD (optional).
+.TP
+.I /usr/share/xml/mathml
+MathML DTD (optional).
+.TP
+.I /usr/share/zoneinfo
+Files for timezone information (optional).
+.TP
+.I /usr/src
+Source files for different parts of the system, included with some packages
+for reference purposes.
+Don't work here with your own projects, as files
+below /usr should be read-only except when installing software (optional).
+.TP
+.I /usr/src/linux
+This was the traditional place for the kernel source.
+Some distributions put here the source for the default kernel they ship.
+You should probably use another directory when building your own kernel.
+.TP
+.I /usr/tmp
+Obsolete.
+This should be a link
+to
+.IR /var/tmp .
+This link is present only for compatibility reasons and shouldn't be used.
+.TP
+.I /var
+This directory contains files which may change in size, such as spool
+and log files.
+.TP
+.I /var/account
+Process accounting logs (optional).
+.TP
+.I /var/adm
+This directory is superseded by
+.I /var/log
+and should be a symbolic link to
+.IR /var/log .
+.TP
+.I /var/backups
+Reserved for historical reasons.
+.TP
+.I /var/cache
+Data cached for programs.
+.TP
+.I /var/cache/fonts
+Locally generated fonts (optional).
+.TP
+.I /var/cache/man
+Locally formatted man pages (optional).
+.TP
+.I /var/cache/www
+WWW proxy or cache data (optional).
+.TP
+.I /var/cache/<package>
+Package specific cache data (optional).
+.TP
+.IR /var/catman/cat[1\-9] " or " /var/cache/man/cat[1\-9]
+These directories contain preformatted manual pages according to their
+man page section.
+(The use of preformatted manual pages is deprecated.)
+.TP
+.I /var/crash
+System crash dumps (optional).
+.TP
+.I /var/cron
+Reserved for historical reasons.
+.TP
+.I /var/games
+Variable game data (optional).
+.TP
+.I /var/lib
+Variable state information for programs.
+.TP
+.I /var/lib/color
+Variable files containing color management information (optional).
+.TP
+.I /var/lib/hwclock
+State directory for hwclock (optional).
+.TP
+.I /var/lib/misc
+Miscellaneous state data.
+.TP
+.I /var/lib/xdm
+X display manager variable data (optional).
+.TP
+.I /var/lib/<editor>
+Editor backup files and state (optional).
+.TP
+.I /var/lib/<name>
+These directories must be used for all distribution packaging support.
+.TP
+.I /var/lib/<package>
+State data for packages and subsystems (optional).
+.TP
+.I /var/lib/<pkgtool>
+Packaging support files (optional).
+.TP
+.I /var/local
+Variable data for
+.IR /usr/local .
+.TP
+.I /var/lock
+Lock files are placed in this directory.
+The naming convention for
+device lock files is
+.I LCK..<device>
+where
+.I <device>
+is the device's name in the filesystem.
+The format used is that of HDU UUCP lock files, that is, lock files
+contain a PID as a 10-byte ASCII decimal number, followed by a newline
+character.
+.TP
+.I /var/log
+Miscellaneous log files.
+.TP
+.I /var/opt
+Variable data for
+.IR /opt .
+.TP
+.I /var/mail
+Users' mailboxes.
+Replaces
+.IR /var/spool/mail .
+.TP
+.I /var/msgs
+Reserved for historical reasons.
+.TP
+.I /var/preserve
+Reserved for historical reasons.
+.TP
+.I /var/run
+Run-time variable files, like files holding process identifiers (PIDs)
+and logged user information
+.IR (utmp) .
+Files in this directory are usually cleared when the system boots.
+.TP
+.I /var/spool
+Spooled (or queued) files for various programs.
+.TP
+.I /var/spool/at
+Spooled jobs for
+.BR at (1).
+.TP
+.I /var/spool/cron
+Spooled jobs for
+.BR cron (8).
+.TP
+.I /var/spool/lpd
+Spooled files for printing (optional).
+.TP
+.I /var/spool/lpd/printer
+Spools for a specific printer (optional).
+.TP
+.I /var/spool/mail
+Replaced by
+.IR /var/mail .
+.TP
+.I /var/spool/mqueue
+Queued outgoing mail (optional).
+.TP
+.I /var/spool/news
+Spool directory for news (optional).
+.TP
+.I /var/spool/rwho
+Spooled files for
+.BR rwhod (8)
+(optional).
+.TP
+.I /var/spool/smail
+Spooled files for the
+.BR smail (1)
+mail delivery program.
+.TP
+.I /var/spool/uucp
+Spooled files for
+.BR uucp (1)
+(optional).
+.TP
+.I /var/tmp
+Like
+.IR /tmp ,
+this directory holds temporary files stored for an unspecified duration.
+.TP
+.I /var/yp
+Database files for NIS,
+formerly known as the Sun Yellow Pages (YP).
+.SH STANDARDS
+.UR https://refspecs.linuxfoundation.org/fhs.shtml
+The Filesystem Hierarchy Standard (FHS), Version 3.0
+.UE ,
+published March 19, 2015
+.SH BUGS
+This list is not exhaustive;
+different distributions and systems may be configured differently.
+.SH SEE ALSO
+.BR find (1),
+.BR ln (1),
+.BR proc (5),
+.BR file\-hierarchy (7),
+.BR mount (8)
+.P
+The Filesystem Hierarchy Standard
diff --git a/man/man7/hostname.7 b/man/man7/hostname.7
new file mode 100644
index 000000000..7b1cf4733
--- /dev/null
+++ b/man/man7/hostname.7
@@ -0,0 +1,97 @@
+.\" Copyright (c) 1987, 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\"     @(#)hostname.7	8.2 (Berkeley) 12/30/93
+.\" $FreeBSD: src/share/man/man7/hostname.7,v 1.7 2004/07/03 18:29:23 ru Exp $
+.\"
+.\" 2008-06-11, mtk, Taken from FreeBSD 6.2 and modified for Linux.
+.\"
+.TH hostname 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+hostname \- hostname resolution description
+.SH DESCRIPTION
+Hostnames are domains, where a domain is a hierarchical, dot-separated
+list of subdomains; for example, the machine "monet", in the "example"
+subdomain of the "com" domain would be represented as "monet.example.com".
+.P
+Each element of the hostname must be from 1 to 63 characters long and the
+entire hostname, including the dots, can be at most 253 characters long.
+Valid characters for hostnames are
+.BR ASCII (7)
+letters from
+.I a
+to
+.IR z ,
+the digits from
+.I 0
+to
+.IR 9 ,
+and the hyphen (\-).
+A hostname may not start with a hyphen.
+.P
+Hostnames are often used with network client and server programs,
+which must generally translate the name to an address for use.
+(This task is generally performed by either
+.BR getaddrinfo (3)
+or the obsolete
+.BR gethostbyname (3).)
+.P
+Hostnames are resolved by the NSS framework in glibc according
+to the
+.B hosts
+configuration in
+.BR nsswitch.conf (5).
+The DNS-based name resolver
+(in the
+.B dns
+NSS service module) resolves them in the following fashion.
+.P
+If the name consists of a single component, that is, contains no dot,
+and if the environment variable
+.B HOSTALIASES
+is set to the name of a file,
+that file is searched for any string matching the input hostname.
+The file should consist of lines made up of two white-space separated strings,
+the first of which is the hostname alias,
+and the second of which is the complete hostname
+to be substituted for that alias.
+If a case-insensitive match is found between the hostname to be resolved
+and the first field of a line in the file, the substituted name is looked
+up with no further processing.
+.P
+If the input name ends with a trailing dot,
+the trailing dot is removed,
+and the remaining name is looked up with no further processing.
+.P
+If the input name does not end with a trailing dot, it is looked up
+by searching through a list of domains until a match is found.
+The default search list includes first the local domain,
+then its parent domains with at least 2 name components (longest first).
+For example,
+in the domain cs.example.com, the name lithium.cchem will be checked first
+as lithium.cchem.cs.example and then as lithium.cchem.example.com.
+lithium.cchem.com will not be tried, as there is only one component
+remaining from the local domain.
+The search path can be changed from the default
+by a system-wide configuration file (see
+.BR resolver (5)).
+.SH SEE ALSO
+.BR getaddrinfo (3),
+.BR gethostbyname (3),
+.BR nsswitch.conf (5),
+.BR resolver (5),
+.BR mailaddr (7),
+.BR named (8)
+.P
+.UR http://www.ietf.org\:/rfc\:/rfc1123.txt
+IETF RFC\ 1123
+.UE
+.P
+.UR http://www.ietf.org\:/rfc\:/rfc1178.txt
+IETF RFC\ 1178
+.UE
+.\" .SH HISTORY
+.\" Hostname appeared in
+.\" 4.2BSD.
diff --git a/man/man7/icmp.7 b/man/man7/icmp.7
new file mode 100644
index 000000000..da6959660
--- /dev/null
+++ b/man/man7/icmp.7
@@ -0,0 +1,196 @@
+'\" t
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: icmp.7,v 1.6 2000/08/14 08:03:45 ak Exp $
+.\"
+.TH icmp 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+icmp \- Linux IPv4 ICMP kernel module.
+.SH DESCRIPTION
+This kernel protocol module implements the Internet Control
+Message Protocol defined in RFC\ 792.
+It is used to signal error conditions and for diagnosis.
+The user doesn't interact directly with this module;
+instead it communicates with the other protocols in the kernel
+and these pass the ICMP errors to the application layers.
+The kernel ICMP module also answers ICMP requests.
+.P
+A user protocol may receive ICMP packets for all local sockets by opening
+a raw socket with the protocol
+.BR IPPROTO_ICMP .
+See
+.BR raw (7)
+for more information.
+The types of ICMP packets passed to the socket can be filtered using the
+.B ICMP_FILTER
+socket option.
+ICMP packets are always processed by the kernel too, even
+when passed to a user socket.
+.P
+Linux limits the rate of ICMP error packets to each destination.
+.B ICMP_REDIRECT
+and
+.B ICMP_DEST_UNREACH
+are also limited by the destination route of the incoming packets.
+.SS /proc interfaces
+ICMP supports a set of
+.I /proc
+interfaces to configure some global IP parameters.
+The parameters can be accessed by reading or writing files in the directory
+.IR /proc/sys/net/ipv4/ .
+Most of these parameters are rate limitations for specific ICMP types.
+Linux 2.2 uses a token bucket filter to limit ICMPs.
+.\" FIXME . better description needed
+The value is the timeout in jiffies until the token bucket filter is
+cleared after a burst.
+A jiffy is a system dependent unit, usually 10ms on i386 and
+about 1ms on alpha and ia64.
+.TP
+.IR icmp_destunreach_rate " (Linux 2.2 to Linux 2.4.9)"
+.\" Precisely: from Linux 2.1.102
+Maximum rate to send ICMP Destination Unreachable packets.
+This limits the rate at which packets are sent to any individual
+route or destination.
+The limit does not affect sending of
+.B ICMP_FRAG_NEEDED
+packets needed for path MTU discovery.
+.TP
+.IR icmp_echo_ignore_all " (since Linux 2.2)"
+.\" Precisely: 2.1.68
+If this value is nonzero, Linux will ignore all
+.B ICMP_ECHO
+requests.
+.TP
+.IR icmp_echo_ignore_broadcasts " (since Linux 2.2)"
+.\" Precisely: from Linux 2.1.68
+If this value is nonzero, Linux will ignore all
+.B ICMP_ECHO
+packets sent to broadcast addresses.
+.TP
+.IR icmp_echoreply_rate " (Linux 2.2 to Linux 2.4.9)"
+.\" Precisely: from Linux 2.1.102
+Maximum rate for sending
+.B ICMP_ECHOREPLY
+packets in response to
+.B ICMP_ECHOREQUEST
+packets.
+.TP
+.IR icmp_errors_use_inbound_ifaddr " (Boolean; default: disabled; since Linux 2.6.12)"
+.\" The following taken from Linux 2.6.28-rc4 Documentation/networking/ip-sysctl.txt
+If disabled, ICMP error messages are sent with the primary address of
+the exiting interface.
+.IP
+If enabled, the message will be sent with the primary address of
+the interface that received the packet that caused the ICMP error.
+This is the behavior that many network administrators will expect from
+a router.
+And it can make debugging complicated network layouts much easier.
+.IP
+Note that if no primary address exists for the interface selected,
+then the primary address of the first non-loopback interface that
+has one will be used regardless of this setting.
+.TP
+.IR icmp_ignore_bogus_error_responses " (Boolean; default: disabled; since Linux 2.2)"
+.\" precisely: since Linux 2.1.32
+.\" The following taken from Linux 2.6.28-rc4 Documentation/networking/ip-sysctl.txt
+Some routers violate RFC1122 by sending bogus responses to broadcast frames.
+Such violations are normally logged via a kernel warning.
+If this parameter is enabled, the kernel will not give such warnings,
+which will avoid log file clutter.
+.TP
+.IR icmp_paramprob_rate " (Linux 2.2 to Linux 2.4.9)"
+.\" Precisely: from Linux 2.1.102
+Maximum rate for sending
+.B ICMP_PARAMETERPROB
+packets.
+These packets are sent when a packet arrives with an invalid IP header.
+.TP
+.IR icmp_ratelimit " (integer; default: 1000; since Linux 2.4.10)"
+.\" The following taken from Linux 2.6.28-rc4 Documentation/networking/ip-sysctl.txt
+Limit the maximum rates for sending ICMP packets whose type matches
+.I icmp_ratemask
+(see below) to specific targets.
+0 to disable any limiting,
+otherwise the minimum space between responses in milliseconds.
+.TP
+.IR icmp_ratemask " (integer; default: see below; since Linux 2.4.10)"
+.\" The following taken from Linux 2.6.28-rc4 Documentation/networking/ip-sysctl.txt
+Mask made of ICMP types for which rates are being limited.
+.IP
+Significant bits: IHGFEDCBA9876543210
+.br
+Default mask:     0000001100000011000 (0x1818)
+.IP
+Bit definitions (see the Linux kernel source file
+.IR include/linux/icmp.h ):
+.RS 12
+.TS
+l l.
+0 Echo Reply
+3 Destination Unreachable *
+4 Source Quench *
+5 Redirect
+8 Echo Request
+B Time Exceeded *
+C Parameter Problem *
+D Timestamp Request
+E Timestamp Reply
+F Info Request
+G Info Reply
+H Address Mask Request
+I Address Mask Reply
+.TE
+.RE
+.P
+The bits marked with an asterisk are rate limited by default
+(see the default mask above).
+.TP
+.IR icmp_timeexceed_rate " (Linux 2.2 to Linux 2.4.9)"
+Maximum rate for sending
+.B ICMP_TIME_EXCEEDED
+packets.
+These packets are
+sent to prevent loops when a packet has crossed too many hops.
+.TP
+.IR ping_group_range " (two integers; default: see below; since Linux 2.6.39)"
+Range of the group IDs (minimum and maximum group IDs, inclusive)
+that are allowed to create ICMP Echo sockets.
+The default is "1 0", which
+means no group is allowed to create ICMP Echo sockets.
+.SH VERSIONS
+Support for the
+.B ICMP_ADDRESS
+request was removed in Linux 2.2.
+.P
+Support for
+.B ICMP_SOURCE_QUENCH
+was removed in Linux 2.2.
+.SH NOTES
+As many other implementations don't support
+.B IPPROTO_ICMP
+raw sockets, this feature
+should not be relied on in portable programs.
+.\" not really true ATM
+.\" .P
+.\" Linux ICMP should be compliant to RFC 1122.
+.P
+.B ICMP_REDIRECT
+packets are not sent when Linux is not acting as a router.
+They are also accepted only from the old gateway defined in the
+routing table and the redirect routes are expired after some time.
+.P
+The 64-bit timestamp returned by
+.B ICMP_TIMESTAMP
+is in milliseconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
+.P
+Linux ICMP internally uses a raw socket to send ICMPs.
+This raw socket may appear in
+.BR netstat (8)
+output with a zero inode.
+.SH SEE ALSO
+.BR ip (7),
+.BR rdisc (8)
+.P
+RFC\ 792 for a description of the ICMP protocol.
diff --git a/man/man7/inode.7 b/man/man7/inode.7
new file mode 100644
index 000000000..45bf71467
--- /dev/null
+++ b/man/man7/inode.7
@@ -0,0 +1,480 @@
+'\" t
+.\" Copyright (c) 2017 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH inode 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inode \- file inode information
+.SH DESCRIPTION
+Each file has an inode containing metadata about the file.
+An application can retrieve this metadata using
+.BR stat (2)
+(or related calls), which returns a
+.I stat
+structure, or
+.BR statx (2),
+which returns a
+.I statx
+structure.
+.P
+The following is a list of the information typically found in,
+or associated with, the file inode,
+with the names of the corresponding structure fields returned by
+.BR stat (2)
+and
+.BR statx (2):
+.TP
+Device where inode resides
+\fIstat.st_dev\fP; \fIstatx.stx_dev_minor\fP and \fIstatx.stx_dev_major\fP
+.IP
+Each inode (as well as the associated file) resides in a filesystem
+that is hosted on a device.
+That device is identified by the combination of its major ID
+(which identifies the general class of device)
+and minor ID (which identifies a specific instance in the general class).
+.TP
+Inode number
+\fIstat.st_ino\fP; \fIstatx.stx_ino\fP
+.IP
+Each file in a filesystem has a unique inode number.
+Inode numbers are guaranteed to be unique only within a filesystem
+(i.e., the same inode numbers may be used by different filesystems,
+which is the reason that hard links may not cross filesystem boundaries).
+This field contains the file's inode number.
+.TP
+File type and mode
+\fIstat.st_mode\fP; \fIstatx.stx_mode\fP
+.IP
+See the discussion of file type and mode, below.
+.TP
+Link count
+\fIstat.st_nlink\fP; \fIstatx.stx_nlink\fP
+.IP
+This field contains the number of hard links to the file.
+Additional links to an existing file are created using
+.BR link (2).
+.TP
+User ID
+\fIstat.st_uid\fP; \fIstatx.stx_uid\fP
+.IP
+This field records the user ID of the owner of the file.
+For newly created files,
+the file user ID is the effective user ID of the creating process.
+The user ID of a file can be changed using
+.BR chown (2).
+.TP
+Group ID
+\fIstat.st_gid\fP; \fIstatx.stx_gid\fP
+.IP
+The inode records the ID of the group owner of the file.
+For newly created files,
+the file group ID is either the group ID of the parent directory or
+the effective group ID of the creating process,
+depending on whether or not the set-group-ID bit
+is set on the parent directory (see below).
+The group ID of a file can be changed using
+.BR chown (2).
+.TP
+Device represented by this inode
+\fIstat.st_rdev\fP; \fIstatx.stx_rdev_minor\fP and \fIstatx.stx_rdev_major\fP
+.IP
+If this file (inode) represents a device,
+then the inode records the major and minor ID of that device.
+.TP
+File size
+\fIstat.st_size\fP; \fIstatx.stx_size\fP
+.IP
+This field gives the size of the file (if it is a regular
+file or a symbolic link) in bytes.
+The size of a symbolic link is the length of the pathname
+it contains, without a terminating null byte.
+.TP
+Preferred block size for I/O
+\fIstat.st_blksize\fP; \fIstatx.stx_blksize\fP
+.IP
+This field gives the "preferred" blocksize for efficient filesystem I/O.
+(Writing to a file in smaller chunks may cause
+an inefficient read-modify-rewrite.)
+.TP
+Number of blocks allocated to the file
+\fIstat.st_blocks\fP; \fIstatx.stx_blocks\fP
+.IP
+This field indicates the number of blocks allocated to the file,
+512-byte units,
+(This may be smaller than
+.IR st_size /512
+when the file has holes.)
+.IP
+The POSIX.1 standard notes
+.\" Rationale for sys/stat.h in POSIX.1-2008
+that the unit for the
+.I st_blocks
+member of the
+.I stat
+structure is not defined by the standard.
+On many  implementations it is 512 bytes;
+on a few systems, a different unit is used, such as 1024.
+Furthermore, the unit may differ on a per-filesystem basis.
+.TP
+Last access timestamp (atime)
+\fIstat.st_atime\fP; \fIstatx.stx_atime\fP
+.IP
+This is the file's last access timestamp.
+It is changed by file accesses, for example, by
+.BR execve (2),
+.BR mknod (2),
+.BR pipe (2),
+.BR utime (2),
+and
+.BR read (2)
+(of more than zero bytes).
+Other interfaces, such as
+.BR mmap (2),
+may or may not update the atime timestamp
+.IP
+Some filesystem types allow mounting in such a way that file
+and/or directory accesses do not cause an update of the atime timestamp.
+(See
+.IR noatime ,
+.IR nodiratime ,
+and
+.I relatime
+in
+.BR mount (8),
+and related information in
+.BR mount (2).)
+In addition, the atime timestamp
+is not updated if a file is opened with the
+.B O_NOATIME
+flag; see
+.BR open (2).
+.TP
+File creation (birth) timestamp (btime)
+(not returned in the \fIstat\fP structure); \fIstatx.stx_btime\fP
+.IP
+The file's creation timestamp.
+This is set on file creation and not changed subsequently.
+.IP
+The btime timestamp was not historically present on UNIX systems
+and is not currently supported by most Linux filesystems.
+.\" FIXME Is it supported on ext4 and XFS?
+.TP
+Last modification timestamp (mtime)
+\fIstat.st_mtime\fP; \fIstatx.stx_mtime\fP
+.IP
+This is the file's last modification timestamp.
+It is changed by file modifications, for example, by
+.BR mknod (2),
+.BR truncate (2),
+.BR utime (2),
+and
+.BR write (2)
+(of more than zero bytes).
+Moreover, the mtime timestamp
+of a directory is changed by the creation or deletion of files
+in that directory.
+The mtime timestamp is
+.I not
+changed for changes in owner, group, hard link count, or mode.
+.TP
+Last status change timestamp (ctime)
+\fIstat.st_ctime\fP; \fIstatx.stx_ctime\fP
+.IP
+This is the file's last status change timestamp.
+It is changed by writing or by setting inode information
+(i.e., owner, group, link count, mode, etc.).
+.P
+The timestamp fields report time measured with a zero point at the
+.IR Epoch ,
+1970-01-01 00:00:00 +0000, UTC (see
+.BR time (7)).
+.P
+Nanosecond timestamps are supported on XFS, JFS, Btrfs, and
+ext4 (since Linux 2.6.23).
+.\" commit ef7f38359ea8b3e9c7f2cae9a4d4935f55ca9e80
+Nanosecond timestamps are not supported in ext2, ext3, and Reiserfs.
+In order to return timestamps with nanosecond precision,
+the timestamp fields in the
+.I stat
+and
+.I statx
+structures are defined as structures that include a nanosecond component.
+See
+.BR stat (2)
+and
+.BR statx (2)
+for details.
+On filesystems that do not support subsecond timestamps,
+the nanosecond fields in the
+.I stat
+and
+.I statx
+structures are returned with the value 0.
+.\"
+.SS The file type and mode
+The
+.I stat.st_mode
+field (for
+.BR statx (2),
+the
+.I statx.stx_mode
+field) contains the file type and mode.
+.P
+POSIX refers to the
+.I stat.st_mode
+bits corresponding to the mask
+.B S_IFMT
+(see below) as the
+.IR "file type" ,
+the 12 bits corresponding to the mask 07777 as the
+.I file mode bits
+and the least significant 9 bits (0777) as the
+.IR "file permission bits" .
+.P
+The following mask values are defined for the file type:
+.in +4n
+.TS
+lB l l.
+S_IFMT	0170000	bit mask for the file type bit field
+
+S_IFSOCK	0140000	socket
+S_IFLNK	0120000	symbolic link
+S_IFREG	0100000	regular file
+S_IFBLK	0060000	block device
+S_IFDIR	0040000	directory
+S_IFCHR	0020000	character device
+S_IFIFO	0010000	FIFO
+.TE
+.in
+.P
+Thus, to test for a regular file (for example), one could write:
+.P
+.in +4n
+.EX
+stat(pathname, &sb);
+if ((sb.st_mode & S_IFMT) == S_IFREG) {
+    /* Handle regular file */
+}
+.EE
+.in
+.P
+Because tests of the above form are common, additional
+macros are defined by POSIX to allow the test of the file type in
+.I st_mode
+to be written more concisely:
+.RS 4
+.TP 1.2i
+.BR S_ISREG (m)
+is it a regular file?
+.TP
+.BR S_ISDIR (m)
+directory?
+.TP
+.BR S_ISCHR (m)
+character device?
+.TP
+.BR S_ISBLK (m)
+block device?
+.TP
+.BR S_ISFIFO (m)
+FIFO (named pipe)?
+.TP
+.BR S_ISLNK (m)
+symbolic link?  (Not in POSIX.1-1996.)
+.TP
+.BR S_ISSOCK (m)
+socket?  (Not in POSIX.1-1996.)
+.RE
+.P
+The preceding code snippet could thus be rewritten as:
+.P
+.in +4n
+.EX
+stat(pathname, &sb);
+if (S_ISREG(sb.st_mode)) {
+    /* Handle regular file */
+}
+.EE
+.in
+.P
+The definitions of most of the above file type test macros
+are provided if any of the following feature test macros is defined:
+.B _BSD_SOURCE
+(in glibc 2.19 and earlier),
+.B _SVID_SOURCE
+(in glibc 2.19 and earlier),
+or
+.B _DEFAULT_SOURCE
+(in glibc 2.20 and later).
+In addition, definitions of all of the above macros except
+.B S_IFSOCK
+and
+.BR S_ISSOCK ()
+are provided if
+.B _XOPEN_SOURCE
+is defined.
+.P
+The definition of
+.B S_IFSOCK
+can also be exposed either by defining
+.B _XOPEN_SOURCE
+with a value of 500 or greater or (since glibc 2.24) by defining both
+.B _XOPEN_SOURCE
+and
+.BR _XOPEN_SOURCE_EXTENDED .
+.P
+The definition of
+.BR S_ISSOCK ()
+is exposed if any of the following feature test macros is defined:
+.B _BSD_SOURCE
+(in glibc 2.19 and earlier),
+.B _DEFAULT_SOURCE
+(in glibc 2.20 and later),
+.B _XOPEN_SOURCE
+with a value of 500 or greater,
+.B _POSIX_C_SOURCE
+with a value of 200112L or greater, or (since glibc 2.24) by defining both
+.B _XOPEN_SOURCE
+and
+.BR _XOPEN_SOURCE_EXTENDED .
+.P
+The following mask values are defined for
+the file mode component of the
+.I st_mode
+field:
+.in +4n
+.TS
+lB l lx.
+S_ISUID	  04000	T{
+set-user-ID bit (see \fBexecve\fP(2))
+T}
+S_ISGID	  02000	T{
+set-group-ID bit (see below)
+T}
+S_ISVTX	  01000	T{
+sticky bit (see below)
+T}
+
+S_IRWXU	  00700	T{
+owner has read, write, and execute permission
+T}
+S_IRUSR	  00400	T{
+owner has read permission
+T}
+S_IWUSR	  00200	T{
+owner has write permission
+T}
+S_IXUSR	  00100	T{
+owner has execute permission
+T}
+
+S_IRWXG	  00070	T{
+group has read, write, and execute permission
+T}
+S_IRGRP	  00040	T{
+group has read permission
+T}
+S_IWGRP	  00020	T{
+group has write permission
+T}
+S_IXGRP	  00010	T{
+group has execute permission
+T}
+
+S_IRWXO	  00007	T{
+others (not in group) have read, write, and execute permission
+T}
+S_IROTH	  00004	T{
+others have read permission
+T}
+S_IWOTH	  00002	T{
+others have write permission
+T}
+S_IXOTH	  00001	T{
+others have execute permission
+T}
+.TE
+.in
+.P
+The set-group-ID bit
+.RB ( S_ISGID )
+has several special uses.
+For a directory, it indicates that BSD semantics are to be used
+for that directory: files created there inherit their group ID from
+the directory, not from the effective group ID of the creating process,
+and directories created there will also get the
+.B S_ISGID
+bit set.
+For an executable file, the set-group-ID bit causes the effective group ID
+of a process that executes the file to change as described in
+.BR execve (2).
+For a file that does not have the group execution bit
+.RB ( S_IXGRP )
+set,
+the set-group-ID bit indicates mandatory file/record locking.
+.P
+The sticky bit
+.RB ( S_ISVTX )
+on a directory means that a file
+in that directory can be renamed or deleted only by the owner
+of the file, by the owner of the directory, and by a privileged
+process.
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.P
+POSIX.1-1990 did not describe the
+.BR S_IFMT ,
+.BR S_IFSOCK ,
+.BR S_IFLNK ,
+.BR S_IFREG ,
+.BR S_IFBLK ,
+.BR S_IFDIR ,
+.BR S_IFCHR ,
+.BR S_IFIFO ,
+and
+.B S_ISVTX
+constants, but instead specified the use of
+the macros
+.BR S_ISDIR ()
+and so on.
+.P
+The
+.BR S_ISLNK ()
+and
+.BR S_ISSOCK ()
+macros were not in
+POSIX.1-1996;
+the former is from SVID 4, the latter from SUSv2.
+.P
+UNIX\ V7 (and later systems) had
+.BR S_IREAD ,
+.BR S_IWRITE ,
+.BR S_IEXEC ,
+and
+where POSIX
+prescribes the synonyms
+.BR S_IRUSR ,
+.BR S_IWUSR ,
+and
+.BR S_IXUSR .
+.SH NOTES
+For pseudofiles that are autogenerated by the kernel, the file size
+(\fIstat.st_size\fP; \fIstatx.stx_size\fP)
+reported by the kernel is not accurate.
+For example, the value 0 is returned for many files under the
+.I /proc
+directory,
+while various files under
+.I /sys
+report a size of 4096 bytes, even though the file content is smaller.
+For such files, one should simply try to read as many bytes as possible
+(and append \[aq]\e0\[aq] to the returned buffer
+if it is to be interpreted as a string).
+.SH SEE ALSO
+.BR stat (1),
+.BR stat (2),
+.BR statx (2),
+.BR symlink (7)
diff --git a/man/man7/inotify.7 b/man/man7/inotify.7
new file mode 100644
index 000000000..bd3972f80
--- /dev/null
+++ b/man/man7/inotify.7
@@ -0,0 +1,1100 @@
+.\" Copyright (C) 2006, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) 2014 Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH inotify 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+inotify \- monitoring filesystem events
+.SH DESCRIPTION
+The
+.I inotify
+API provides a mechanism for monitoring filesystem events.
+Inotify can be used to monitor individual files,
+or to monitor directories.
+When a directory is monitored, inotify will return events
+for the directory itself, and for files inside the directory.
+.P
+The following system calls are used with this API:
+.IP \[bu] 3
+.BR inotify_init (2)
+creates an inotify instance and returns a file descriptor
+referring to the inotify instance.
+The more recent
+.BR inotify_init1 (2)
+is like
+.BR inotify_init (2),
+but has a
+.I flags
+argument that provides access to some extra functionality.
+.IP \[bu]
+.BR inotify_add_watch (2)
+manipulates the "watch list" associated with an inotify instance.
+Each item ("watch") in the watch list specifies the pathname of
+a file or directory,
+along with some set of events that the kernel should monitor for the
+file referred to by that pathname.
+.BR inotify_add_watch (2)
+either creates a new watch item, or modifies an existing watch.
+Each watch has a unique "watch descriptor", an integer
+returned by
+.BR inotify_add_watch (2)
+when the watch is created.
+.IP \[bu]
+When events occur for monitored files and directories,
+those events are made available to the application as structured data that
+can be read from the inotify file descriptor using
+.BR read (2)
+(see below).
+.IP \[bu]
+.BR inotify_rm_watch (2)
+removes an item from an inotify watch list.
+.IP \[bu]
+When all file descriptors referring to an inotify
+instance have been closed (using
+.BR close (2)),
+the underlying object and its resources are
+freed for reuse by the kernel;
+all associated watches are automatically freed.
+.P
+With careful programming,
+an application can use inotify to efficiently monitor and cache
+the state of a set of filesystem objects.
+However, robust applications should allow for the fact that bugs
+in the monitoring logic or races of the kind described below
+may leave the cache inconsistent with the filesystem state.
+It is probably wise to do some consistency checking,
+and rebuild the cache when inconsistencies are detected.
+.SS Reading events from an inotify file descriptor
+To determine what events have occurred, an application
+.BR read (2)s
+from the inotify file descriptor.
+If no events have so far occurred, then,
+assuming a blocking file descriptor,
+.BR read (2)
+will block until at least one event occurs
+(unless interrupted by a signal,
+in which case the call fails with the error
+.BR EINTR ;
+see
+.BR signal (7)).
+.P
+Each successful
+.BR read (2)
+returns a buffer containing one or more of the following structures:
+.P
+.in +4n
+.EX
+struct inotify_event {
+    int      wd;       /* Watch descriptor */
+.\" FIXME . The type of the 'wd' field should probably be "int32_t".
+.\" I submitted a patch to fix this.  See the LKML thread
+.\" "[patch] Fix type errors in inotify interfaces", 18 Nov 2008
+.\" glibc bug filed: https://www.sourceware.org/bugzilla/show_bug.cgi?id=7040
+    uint32_t mask;     /* Mask describing event */
+    uint32_t cookie;   /* Unique cookie associating related
+                          events (for rename(2)) */
+    uint32_t len;      /* Size of \fIname\fP field */
+    char     name[];   /* Optional null\-terminated name */
+};
+.EE
+.in
+.P
+.I wd
+identifies the watch for which this event occurs.
+It is one of the watch descriptors returned by a previous call to
+.BR inotify_add_watch (2).
+.P
+.I mask
+contains bits that describe the event that occurred (see below).
+.P
+.I cookie
+is a unique integer that connects related events.
+Currently, this is used only for rename events, and
+allows the resulting pair of
+.B IN_MOVED_FROM
+and
+.B IN_MOVED_TO
+events to be connected by the application.
+For all other event types,
+.I cookie
+is set to 0.
+.P
+The
+.I name
+field is present only when an event is returned
+for a file inside a watched directory;
+it identifies the filename within the watched directory.
+This filename is null-terminated,
+and may include further null bytes (\[aq]\e0\[aq])
+to align subsequent reads to a suitable address boundary.
+.P
+The
+.I len
+field counts all of the bytes in
+.IR name ,
+including the null bytes;
+the length of each
+.I inotify_event
+structure is thus
+.IR "sizeof(struct inotify_event)+len" .
+.P
+The behavior when the buffer given to
+.BR read (2)
+is too small to return information about the next event depends
+on the kernel version: before Linux 2.6.21,
+.BR read (2)
+returns 0; since Linux 2.6.21,
+.BR read (2)
+fails with the error
+.BR EINVAL .
+Specifying a buffer of size
+.P
+.in +4n
+.EX
+sizeof(struct inotify_event) + NAME_MAX + 1
+.EE
+.in
+.P
+will be sufficient to read at least one event.
+.SS inotify events
+The
+.BR inotify_add_watch (2)
+.I mask
+argument and the
+.I mask
+field of the
+.I inotify_event
+structure returned when
+.BR read (2)ing
+an inotify file descriptor are both bit masks identifying
+inotify events.
+The following bits can be specified in
+.I mask
+when calling
+.BR inotify_add_watch (2)
+and may be returned in the
+.I mask
+field returned by
+.BR read (2):
+.RS 4
+.TP
+.BR IN_ACCESS " (+)"
+File was accessed (e.g.,
+.BR read (2),
+.BR execve (2)).
+.TP
+.BR IN_ATTRIB " (*)"
+Metadata changed\[em]for example, permissions (e.g.,
+.BR chmod (2)),
+timestamps (e.g.,
+.BR utimensat (2)),
+extended attributes
+.RB ( setxattr (2)),
+link count (since Linux 2.6.25; e.g.,
+.\" FIXME .
+.\" Events do not occur for link count changes on a file inside a monitored
+.\" directory. This differs from other metadata changes for files inside
+.\" a monitored directory.
+for the target of
+.BR link (2)
+and for
+.BR unlink (2)),
+and user/group ID (e.g.,
+.BR chown (2)).
+.TP
+.BR IN_CLOSE_WRITE " (+)"
+File opened for writing was closed.
+.TP
+.BR IN_CLOSE_NOWRITE " (*)"
+File or directory not opened for writing was closed.
+.TP
+.BR IN_CREATE " (+)"
+File/directory created in watched directory (e.g.,
+.BR open (2)
+.BR O_CREAT ,
+.BR mkdir (2),
+.BR link (2),
+.BR symlink (2),
+.BR bind (2)
+on a UNIX domain socket).
+.TP
+.BR IN_DELETE " (+)"
+File/directory deleted from watched directory.
+.TP
+.B IN_DELETE_SELF
+Watched file/directory was itself deleted.
+(This event also occurs if an object is moved to another filesystem,
+since
+.BR mv (1)
+in effect copies the file to the other filesystem and
+then deletes it from the original filesystem.)
+In addition, an
+.B IN_IGNORED
+event will subsequently be generated for the watch descriptor.
+.TP
+.BR IN_MODIFY " (+)"
+File was modified (e.g.,
+.BR write (2),
+.BR truncate (2)).
+.TP
+.B IN_MOVE_SELF
+Watched file/directory was itself moved.
+.TP
+.BR IN_MOVED_FROM " (+)"
+Generated for the directory containing the old filename
+when a file is renamed.
+.TP
+.BR IN_MOVED_TO " (+)"
+Generated for the directory containing the new filename
+when a file is renamed.
+.TP
+.BR IN_OPEN " (*)"
+File or directory was opened.
+.RE
+.P
+Inotify monitoring is inode-based: when monitoring a file
+(but not when monitoring the directory containing a file),
+an event can be generated for activity on any link to the file
+(in the same or a different directory).
+.P
+When monitoring a directory:
+.IP \[bu] 3
+the events marked above with an asterisk (*) can occur both
+for the directory itself and for objects inside the directory; and
+.IP \[bu]
+the events marked with a plus sign (+) occur only for objects
+inside the directory (not for the directory itself).
+.P
+.IR Note :
+when monitoring a directory,
+events are not generated for the files inside the directory
+when the events are performed via a pathname (i.e., a link)
+that lies outside the monitored directory.
+.P
+When events are generated for objects inside a watched directory, the
+.I name
+field in the returned
+.I inotify_event
+structure identifies the name of the file within the directory.
+.P
+The
+.B IN_ALL_EVENTS
+macro is defined as a bit mask of all of the above events.
+This macro can be used as the
+.I mask
+argument when calling
+.BR inotify_add_watch (2).
+.P
+Two additional convenience macros are defined:
+.RS 4
+.TP
+.B IN_MOVE
+Equates to
+.BR "IN_MOVED_FROM | IN_MOVED_TO" .
+.TP
+.B IN_CLOSE
+Equates to
+.BR "IN_CLOSE_WRITE | IN_CLOSE_NOWRITE" .
+.RE
+.P
+The following further bits can be specified in
+.I mask
+when calling
+.BR inotify_add_watch (2):
+.RS 4
+.TP
+.BR IN_DONT_FOLLOW " (since Linux 2.6.15)"
+Don't dereference
+.I pathname
+if it is a symbolic link.
+.TP
+.BR IN_EXCL_UNLINK " (since Linux 2.6.36)"
+.\" commit 8c1934c8d70b22ca8333b216aec6c7d09fdbd6a6
+By default, when watching events on the children of a directory,
+events are generated for children even after they have been unlinked
+from the directory.
+This can result in large numbers of uninteresting events for
+some applications (e.g., if watching
+.IR /tmp ,
+in which many applications create temporary files whose
+names are immediately unlinked).
+Specifying
+.B IN_EXCL_UNLINK
+changes the default behavior,
+so that events are not generated for children after
+they have been unlinked from the watched directory.
+.TP
+.B IN_MASK_ADD
+If a watch instance already exists for the filesystem object corresponding to
+.IR pathname ,
+add (OR) the events in
+.I mask
+to the watch mask (instead of replacing the mask);
+the error
+.B EINVAL
+results if
+.B IN_MASK_CREATE
+is also specified.
+.TP
+.B IN_ONESHOT
+Monitor the filesystem object corresponding to
+.I pathname
+for one event, then remove from
+watch list.
+.TP
+.BR IN_ONLYDIR " (since Linux 2.6.15)"
+Watch
+.I pathname
+only if it is a directory;
+the error
+.B ENOTDIR
+results if
+.I pathname
+is not a directory.
+Using this flag provides an application with a race-free way of
+ensuring that the monitored object is a directory.
+.TP
+.BR IN_MASK_CREATE " (since Linux 4.18)"
+Watch
+.I pathname
+only if it does not already have a watch associated with it;
+the error
+.B EEXIST
+results if
+.I pathname
+is already being watched.
+.IP
+Using this flag provides an application with a way of ensuring
+that new watches do not modify existing ones.
+This is useful because multiple paths may refer to the same inode,
+and multiple calls to
+.BR inotify_add_watch (2)
+without this flag may clobber existing watch masks.
+.RE
+.P
+The following bits may be set in the
+.I mask
+field returned by
+.BR read (2):
+.RS 4
+.TP
+.B IN_IGNORED
+Watch was removed explicitly
+.RB ( inotify_rm_watch (2))
+or automatically (file was deleted, or filesystem was unmounted).
+See also BUGS.
+.TP
+.B IN_ISDIR
+Subject of this event is a directory.
+.TP
+.B IN_Q_OVERFLOW
+Event queue overflowed
+.RI ( wd
+is \-1 for this event).
+.TP
+.B IN_UNMOUNT
+Filesystem containing watched object was unmounted.
+In addition, an
+.B IN_IGNORED
+event will subsequently be generated for the watch descriptor.
+.RE
+.SS Examples
+Suppose an application is watching the directory
+.I dir
+and the file
+.I dir/myfile
+for all events.
+The examples below show some events that will be generated
+for these two objects.
+.RS 4
+.TP
+fd = open("dir/myfile", O_RDWR);
+Generates
+.B IN_OPEN
+events for both
+.I dir
+and
+.IR dir/myfile .
+.TP
+read(fd, buf, count);
+Generates
+.B IN_ACCESS
+events for both
+.I dir
+and
+.IR dir/myfile .
+.TP
+write(fd, buf, count);
+Generates
+.B IN_MODIFY
+events for both
+.I dir
+and
+.IR dir/myfile .
+.TP
+fchmod(fd, mode);
+Generates
+.B IN_ATTRIB
+events for both
+.I dir
+and
+.IR dir/myfile .
+.TP
+close(fd);
+Generates
+.B IN_CLOSE_WRITE
+events for both
+.I dir
+and
+.IR dir/myfile .
+.RE
+.P
+Suppose an application is watching the directories
+.I dir1
+and
+.IR dir2 ,
+and the file
+.IR dir1/myfile .
+The following examples show some events that may be generated.
+.RS 4
+.TP
+link("dir1/myfile", "dir2/new");
+Generates an
+.B IN_ATTRIB
+event for
+.I myfile
+and an
+.B IN_CREATE
+event for
+.IR dir2 .
+.TP
+rename("dir1/myfile", "dir2/myfile");
+Generates an
+.B IN_MOVED_FROM
+event for
+.IR dir1 ,
+an
+.B IN_MOVED_TO
+event for
+.IR dir2 ,
+and an
+.B IN_MOVE_SELF
+event for
+.IR myfile .
+The
+.B IN_MOVED_FROM
+and
+.B IN_MOVED_TO
+events will have the same
+.I cookie
+value.
+.RE
+.P
+Suppose that
+.I dir1/xx
+and
+.I dir2/yy
+are (the only) links to the same file, and an application is watching
+.IR dir1 ,
+.IR dir2 ,
+.IR dir1/xx ,
+and
+.IR dir2/yy .
+Executing the following calls in the order given below will generate
+the following events:
+.RS 4
+.TP
+unlink("dir2/yy");
+Generates an
+.B IN_ATTRIB
+event for
+.I xx
+(because its link count changes)
+and an
+.B IN_DELETE
+event for
+.IR dir2 .
+.TP
+unlink("dir1/xx");
+Generates
+.BR IN_ATTRIB ,
+.BR IN_DELETE_SELF ,
+and
+.B IN_IGNORED
+events for
+.IR xx ,
+and an
+.B IN_DELETE
+event for
+.IR dir1 .
+.RE
+.P
+Suppose an application is watching the directory
+.I dir
+and (the empty) directory
+.IR dir/subdir .
+The following examples show some events that may be generated.
+.RS 4
+.TP
+mkdir("dir/new", mode);
+Generates an
+.B "IN_CREATE | IN_ISDIR"
+event for
+.IR dir .
+.TP
+rmdir("dir/subdir");
+Generates
+.B IN_DELETE_SELF
+and
+.B IN_IGNORED
+events for
+.IR subdir ,
+and an
+.B "IN_DELETE | IN_ISDIR"
+event for
+.IR dir .
+.RE
+.SS /proc interfaces
+The following interfaces can be used to limit the amount of
+kernel memory consumed by inotify:
+.TP
+.I /proc/sys/fs/inotify/max_queued_events
+The value in this file is used when an application calls
+.BR inotify_init (2)
+to set an upper limit on the number of events that can be
+queued to the corresponding inotify instance.
+Events in excess of this limit are dropped, but an
+.B IN_Q_OVERFLOW
+event is always generated.
+.TP
+.I /proc/sys/fs/inotify/max_user_instances
+This specifies an upper limit on the number of inotify instances
+that can be created per real user ID.
+.TP
+.I /proc/sys/fs/inotify/max_user_watches
+This specifies an upper limit on the number of watches
+that can be created per real user ID.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Inotify was merged into Linux 2.6.13.
+The required library interfaces were added in glibc 2.4.
+.RB ( IN_DONT_FOLLOW ,
+.BR IN_MASK_ADD ,
+and
+.B IN_ONLYDIR
+were added in glibc 2.5.)
+.SH NOTES
+Inotify file descriptors can be monitored using
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7).
+When an event is available, the file descriptor indicates as readable.
+.P
+Since Linux 2.6.25,
+signal-driven I/O notification is available for inotify file descriptors;
+see the discussion of
+.B F_SETFL
+(for setting the
+.B O_ASYNC
+flag),
+.BR F_SETOWN ,
+and
+.B F_SETSIG
+in
+.BR fcntl (2).
+The
+.I siginfo_t
+structure (described in
+.BR sigaction (2))
+that is passed to the signal handler has the following fields set:
+.I si_fd
+is set to the inotify file descriptor number;
+.I si_signo
+is set to the signal number;
+.I si_code
+is set to
+.BR POLL_IN ;
+and
+.B POLLIN
+is set in
+.IR si_band .
+.P
+If successive output inotify events produced on the
+inotify file descriptor are identical (same
+.IR wd ,
+.IR mask ,
+.IR cookie ,
+and
+.IR name ),
+then they are coalesced into a single event if the
+older event has not yet been read (but see BUGS).
+This reduces the amount of kernel memory required for the event queue,
+but also means that an application can't use inotify to reliably count
+file events.
+.P
+The events returned by reading from an inotify file descriptor
+form an ordered queue.
+Thus, for example, it is guaranteed that when renaming from
+one directory to another, events will be produced in the
+correct order on the inotify file descriptor.
+.P
+The set of watch descriptors that is being monitored via
+an inotify file descriptor can be viewed via the entry for
+the inotify file descriptor in the process's
+.IR /proc/ pid /fdinfo
+directory.
+See
+.BR proc (5)
+for further details.
+The
+.B FIONREAD
+.BR ioctl (2)
+returns the number of bytes available to read from an
+inotify file descriptor.
+.SS Limitations and caveats
+The inotify API provides no information about the user or process that
+triggered the inotify event.
+In particular, there is no easy
+way for a process that is monitoring events via inotify
+to distinguish events that it triggers
+itself from those that are triggered by other processes.
+.P
+Inotify reports only events that a user-space program triggers through
+the filesystem API.
+As a result, it does not catch remote events that occur
+on network filesystems.
+(Applications must fall back to polling the filesystem
+to catch such events.)
+Furthermore, various pseudo-filesystems such as
+.IR /proc ,
+.IR /sys ,
+and
+.I /dev/pts
+are not monitorable with inotify.
+.P
+The inotify API does not report file accesses and modifications that
+may occur because of
+.BR mmap (2),
+.BR msync (2),
+and
+.BR munmap (2).
+.P
+The inotify API identifies affected files by filename.
+However, by the time an application processes an inotify event,
+the filename may already have been deleted or renamed.
+.P
+The inotify API identifies events via watch descriptors.
+It is the application's responsibility to cache a mapping
+(if one is needed) between watch descriptors and pathnames.
+Be aware that directory renamings may affect multiple cached pathnames.
+.P
+Inotify monitoring of directories is not recursive:
+to monitor subdirectories under a directory,
+additional watches must be created.
+This can take a significant amount time for large directory trees.
+.P
+If monitoring an entire directory subtree,
+and a new subdirectory is created in that tree or an existing directory
+is renamed into that tree,
+be aware that by the time you create a watch for the new subdirectory,
+new files (and subdirectories) may already exist inside the subdirectory.
+Therefore, you may want to scan the contents of the subdirectory
+immediately after adding the watch (and, if desired,
+recursively add watches for any subdirectories that it contains).
+.P
+Note that the event queue can overflow.
+In this case, events are lost.
+Robust applications should handle the possibility of
+lost events gracefully.
+For example, it may be necessary to rebuild part or all of
+the application cache.
+(One simple, but possibly expensive,
+approach is to close the inotify file descriptor, empty the cache,
+create a new inotify file descriptor,
+and then re-create watches and cache entries
+for the objects to be monitored.)
+.P
+If a filesystem is mounted on top of a monitored directory,
+no event is generated, and no events are generated
+for objects immediately under the new mount point.
+If the filesystem is subsequently unmounted,
+events will subsequently be generated for the directory and
+the objects it contains.
+.\"
+.SS Dealing with rename() events
+As noted above, the
+.B IN_MOVED_FROM
+and
+.B IN_MOVED_TO
+event pair that is generated by
+.BR rename (2)
+can be matched up via their shared cookie value.
+However, the task of matching has some challenges.
+.P
+These two events are usually consecutive in the event stream available
+when reading from the inotify file descriptor.
+However, this is not guaranteed.
+If multiple processes are triggering events for monitored objects,
+then (on rare occasions) an arbitrary number of
+other events may appear between the
+.B IN_MOVED_FROM
+and
+.B IN_MOVED_TO
+events.
+Furthermore, it is not guaranteed that the event pair is atomically
+inserted into the queue: there may be a brief interval where the
+.B IN_MOVED_FROM
+has appeared, but the
+.B IN_MOVED_TO
+has not.
+.P
+Matching up the
+.B IN_MOVED_FROM
+and
+.B IN_MOVED_TO
+event pair generated by
+.BR rename (2)
+is thus inherently racy.
+(Don't forget that if an object is renamed outside of a monitored directory,
+there may not even be an
+.B IN_MOVED_TO
+event.)
+Heuristic approaches (e.g., assume the events are always consecutive)
+can be used to ensure a match in most cases,
+but will inevitably miss some cases,
+causing the application to perceive the
+.B IN_MOVED_FROM
+and
+.B IN_MOVED_TO
+events as being unrelated.
+If watch descriptors are destroyed and re-created as a result,
+then those watch descriptors will be inconsistent with
+the watch descriptors in any pending events.
+(Re-creating the inotify file descriptor and rebuilding the cache may
+be useful to deal with this scenario.)
+.P
+Applications should also allow for the possibility that the
+.B IN_MOVED_FROM
+event was the last event that could fit in the buffer
+returned by the current call to
+.BR read (2),
+and the accompanying
+.B IN_MOVED_TO
+event might be fetched only on the next
+.BR read (2),
+which should be done with a (small) timeout to allow for the fact that
+insertion of the
+.BR IN_MOVED_FROM + IN_MOVED_TO
+event pair is not atomic,
+and also the possibility that there may not be any
+.B IN_MOVED_TO
+event.
+.SH BUGS
+Before Linux 3.19,
+.BR fallocate (2)
+did not create any inotify events.
+Since Linux 3.19,
+.\" commit 820c12d5d6c0890bc93dd63893924a13041fdc35
+calls to
+.BR fallocate (2)
+generate
+.B IN_MODIFY
+events.
+.P
+.\" FIXME . kernel commit 611da04f7a31b2208e838be55a42c7a1310ae321
+.\" implies that unmount events were buggy since Linux 2.6.11 to Linux 2.6.36
+.\"
+Before Linux 2.6.16, the
+.B IN_ONESHOT
+.I mask
+flag does not work.
+.P
+As originally designed and implemented, the
+.B IN_ONESHOT
+flag did not cause an
+.B IN_IGNORED
+event to be generated when the watch was dropped after one event.
+However, as an unintended effect of other changes,
+since Linux 2.6.36, an
+.B IN_IGNORED
+event is generated in this case.
+.P
+Before Linux 2.6.25,
+.\" commit 1c17d18e3775485bf1e0ce79575eb637a94494a2
+the kernel code that was intended to coalesce successive identical events
+(i.e., the two most recent events could potentially be coalesced
+if the older had not yet been read)
+instead checked if the most recent event could be coalesced with the
+.I oldest
+unread event.
+.P
+When a watch descriptor is removed by calling
+.BR inotify_rm_watch (2)
+(or because a watch file is deleted or the filesystem
+that contains it is unmounted),
+any pending unread events for that watch descriptor remain available to read.
+As watch descriptors are subsequently allocated with
+.BR inotify_add_watch (2),
+the kernel cycles through the range of possible watch descriptors (1 to
+.BR INT_MAX )
+incrementally.
+When allocating a free watch descriptor, no check is made to see whether that
+watch descriptor number has any pending unread events in the inotify queue.
+Thus, it can happen that a watch descriptor is reallocated even
+when pending unread events exist for a previous incarnation of
+that watch descriptor number, with the result that the application
+might then read those events and interpret them as belonging to
+the file associated with the newly recycled watch descriptor.
+In practice, the likelihood of hitting this bug may be extremely low,
+since it requires that an application cycle through
+.B INT_MAX
+watch descriptors,
+release a watch descriptor while leaving unread events for that
+watch descriptor in the queue,
+and then recycle that watch descriptor.
+For this reason, and because there have been no reports
+of the bug occurring in real-world applications,
+as of Linux 3.15,
+.\" FIXME . https://bugzilla.kernel.org/show_bug.cgi?id=77111
+no kernel changes have yet been made to eliminate this possible bug.
+.SH EXAMPLES
+The following program demonstrates the usage of the inotify API.
+It marks the directories passed as a command-line arguments
+and waits for events of type
+.BR IN_OPEN ,
+.BR IN_CLOSE_NOWRITE ,
+and
+.BR IN_CLOSE_WRITE .
+.P
+The following output was recorded while editing the file
+.I /home/user/temp/foo
+and listing directory
+.IR /tmp .
+Before the file and the directory were opened,
+.B IN_OPEN
+events occurred.
+After the file was closed, an
+.B IN_CLOSE_WRITE
+event occurred.
+After the directory was closed, an
+.B IN_CLOSE_NOWRITE
+event occurred.
+Execution of the program ended when the user pressed the ENTER key.
+.SS Example output
+.in +4n
+.EX
+$ \fB./a.out /tmp /home/user/temp\fP
+Press enter key to terminate.
+Listening for events.
+IN_OPEN: /home/user/temp/foo [file]
+IN_CLOSE_WRITE: /home/user/temp/foo [file]
+IN_OPEN: /tmp/ [directory]
+IN_CLOSE_NOWRITE: /tmp/ [directory]
+\&
+Listening for events stopped.
+.EE
+.in
+.SS Program source
+\&
+.EX
+#include <errno.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/inotify.h>
+#include <unistd.h>
+#include <string.h>
+\&
+/* Read all available inotify events from the file descriptor \[aq]fd\[aq].
+   wd is the table of watch descriptors for the directories in argv.
+   argc is the length of wd and argv.
+   argv is the list of watched directories.
+   Entry 0 of wd and argv is unused. */
+\&
+static void
+handle_events(int fd, int *wd, int argc, char* argv[])
+{
+    /* Some systems cannot read integer variables if they are not
+       properly aligned. On other systems, incorrect alignment may
+       decrease performance. Hence, the buffer used for reading from
+       the inotify file descriptor should have the same alignment as
+       struct inotify_event. */
+\&
+    char buf[4096]
+        __attribute__ ((aligned(__alignof__(struct inotify_event))));
+    const struct inotify_event *event;
+    ssize_t len;
+\&
+    /* Loop while events can be read from inotify file descriptor. */
+\&
+    for (;;) {
+\&
+        /* Read some events. */
+\&
+        len = read(fd, buf, sizeof(buf));
+        if (len == \-1 && errno != EAGAIN) {
+            perror("read");
+            exit(EXIT_FAILURE);
+        }
+\&
+        /* If the nonblocking read() found no events to read, then
+           it returns \-1 with errno set to EAGAIN. In that case,
+           we exit the loop. */
+\&
+        if (len <= 0)
+            break;
+\&
+        /* Loop over all events in the buffer. */
+\&
+        for (char *ptr = buf; ptr < buf + len;
+                ptr += sizeof(struct inotify_event) + event\->len) {
+\&
+            event = (const struct inotify_event *) ptr;
+\&
+            /* Print event type. */
+\&
+            if (event\->mask & IN_OPEN)
+                printf("IN_OPEN: ");
+            if (event\->mask & IN_CLOSE_NOWRITE)
+                printf("IN_CLOSE_NOWRITE: ");
+            if (event\->mask & IN_CLOSE_WRITE)
+                printf("IN_CLOSE_WRITE: ");
+\&
+            /* Print the name of the watched directory. */
+\&
+            for (size_t i = 1; i < argc; ++i) {
+                if (wd[i] == event\->wd) {
+                    printf("%s/", argv[i]);
+                    break;
+                }
+            }
+\&
+            /* Print the name of the file. */
+\&
+            if (event\->len)
+                printf("%s", event\->name);
+\&
+            /* Print type of filesystem object. */
+\&
+            if (event\->mask & IN_ISDIR)
+                printf(" [directory]\en");
+            else
+                printf(" [file]\en");
+        }
+    }
+}
+\&
+int
+main(int argc, char* argv[])
+{
+    char buf;
+    int fd, i, poll_num;
+    int *wd;
+    nfds_t nfds;
+    struct pollfd fds[2];
+\&
+    if (argc < 2) {
+        printf("Usage: %s PATH [PATH ...]\en", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+\&
+    printf("Press ENTER key to terminate.\en");
+\&
+    /* Create the file descriptor for accessing the inotify API. */
+\&
+    fd = inotify_init1(IN_NONBLOCK);
+    if (fd == \-1) {
+        perror("inotify_init1");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Allocate memory for watch descriptors. */
+\&
+    wd = calloc(argc, sizeof(int));
+    if (wd == NULL) {
+        perror("calloc");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Mark directories for events
+       \- file was opened
+       \- file was closed */
+\&
+    for (i = 1; i < argc; i++) {
+        wd[i] = inotify_add_watch(fd, argv[i],
+                                  IN_OPEN | IN_CLOSE);
+        if (wd[i] == \-1) {
+            fprintf(stderr, "Cannot watch \[aq]%s\[aq]: %s\en",
+                    argv[i], strerror(errno));
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    /* Prepare for polling. */
+\&
+    nfds = 2;
+\&
+    fds[0].fd = STDIN_FILENO;       /* Console input */
+    fds[0].events = POLLIN;
+\&
+    fds[1].fd = fd;                 /* Inotify input */
+    fds[1].events = POLLIN;
+\&
+    /* Wait for events and/or terminal input. */
+\&
+    printf("Listening for events.\en");
+    while (1) {
+        poll_num = poll(fds, nfds, \-1);
+        if (poll_num == \-1) {
+            if (errno == EINTR)
+                continue;
+            perror("poll");
+            exit(EXIT_FAILURE);
+        }
+\&
+        if (poll_num > 0) {
+\&
+            if (fds[0].revents & POLLIN) {
+\&
+                /* Console input is available. Empty stdin and quit. */
+\&
+                while (read(STDIN_FILENO, &buf, 1) > 0 && buf != \[aq]\en\[aq])
+                    continue;
+                break;
+            }
+\&
+            if (fds[1].revents & POLLIN) {
+\&
+                /* Inotify events are available. */
+\&
+                handle_events(fd, wd, argc, argv);
+            }
+        }
+    }
+\&
+    printf("Listening for events stopped.\en");
+\&
+    /* Close inotify file descriptor. */
+\&
+    close(fd);
+\&
+    free(wd);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR inotifywait (1),
+.BR inotifywatch (1),
+.BR inotify_add_watch (2),
+.BR inotify_init (2),
+.BR inotify_init1 (2),
+.BR inotify_rm_watch (2),
+.BR read (2),
+.BR stat (2),
+.BR fanotify (7)
+.P
+.I Documentation/filesystems/inotify.txt
+in the Linux kernel source tree
diff --git a/man/man7/intro.7 b/man/man7/intro.7
new file mode 100644
index 000000000..0ed9f73ce
--- /dev/null
+++ b/man/man7/intro.7
@@ -0,0 +1,23 @@
+.\" Copyright (c) 1993 Michael Haardt
+.\" (michael@moria.de), Fri Apr 2 11:32:09 MET DST
+.\" 1993
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified by Thomas Koenig (ig25@rz.uni-karlsruhe.de) 24 Apr 1993
+.\" Modified Sat Jul 24 17:28:08 1993 by Rik Faith (faith@cs.unc.edu)
+.TH intro 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to overview and miscellany section
+.SH DESCRIPTION
+Section 7 of the manual provides overviews on various topics, and
+describes conventions and protocols,
+character set standards, the standard filesystem layout,
+and miscellaneous other things.
+.SH NOTES
+.SS Authors and copyright conditions
+Look at the header of the manual page source for the author(s) and copyright
+conditions.
+Note that these can be different from page to page!
+.SH SEE ALSO
+.BR standards (7)
diff --git a/man/man7/ip.7 b/man/man7/ip.7
new file mode 100644
index 000000000..4fc9bde27
--- /dev/null
+++ b/man/man7/ip.7
@@ -0,0 +1,1541 @@
+'\" t
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: ip.7,v 1.19 2000/12/20 18:10:31 ak Exp $
+.\"
+.\" FIXME The following socket options are yet to be documented
+.\"
+.\" 	IP_XFRM_POLICY (2.5.48)
+.\"	    Needs CAP_NET_ADMIN
+.\"
+.\" 	IP_IPSEC_POLICY (2.5.47)
+.\"	    Needs CAP_NET_ADMIN
+.\"
+.\"	IP_MINTTL (2.6.34)
+.\"	    commit d218d11133d888f9745802146a50255a4781d37a
+.\"	    Author: Stephen Hemminger <shemminger@vyatta.com>
+.\"
+.\"	MCAST_JOIN_GROUP (2.4.22 / 2.6)
+.\"
+.\"	MCAST_BLOCK_SOURCE (2.4.22 / 2.6)
+.\"
+.\"	MCAST_UNBLOCK_SOURCE (2.4.22 / 2.6)
+.\"
+.\"	MCAST_LEAVE_GROUP (2.4.22 / 2.6)
+.\"
+.\"	MCAST_JOIN_SOURCE_GROUP (2.4.22 / 2.6)
+.\"
+.\"	MCAST_LEAVE_SOURCE_GROUP (2.4.22 / 2.6)
+.\"
+.\"	MCAST_MSFILTER (2.4.22 / 2.6)
+.\"
+.\"	IP_UNICAST_IF (3.4)
+.\"	    commit 76e21053b5bf33a07c76f99d27a74238310e3c71
+.\"	    Author: Erich E. Hoover <ehoover@mines.edu>
+.\"
+.TH ip 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ip \- Linux IPv4 protocol implementation
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.\" .B #include <net/netinet.h> -- does not exist anymore
+.\" .B #include <linux/errqueue.h> -- never include <linux/foo.h>
+.B #include <netinet/in.h>
+.B #include <netinet/ip.h>        \fR/* superset of previous */
+.P
+.IB tcp_socket " = socket(AF_INET, SOCK_STREAM, 0);"
+.IB udp_socket " = socket(AF_INET, SOCK_DGRAM, 0);"
+.IB raw_socket " = socket(AF_INET, SOCK_RAW, " protocol ");"
+.fi
+.SH DESCRIPTION
+Linux implements the Internet Protocol, version 4,
+described in RFC\ 791 and RFC\ 1122.
+.B ip
+contains a level 2 multicasting implementation conforming to RFC\ 1112.
+It also contains an IP router including a packet filter.
+.P
+The programming interface is BSD-sockets compatible.
+For more information on sockets, see
+.BR socket (7).
+.P
+An IP socket is created using
+.BR socket (2):
+.P
+.in +4n
+.EX
+socket(AF_INET, socket_type, protocol);
+.EE
+.in
+.P
+Valid socket types include
+.B SOCK_STREAM
+to open a stream socket,
+.B SOCK_DGRAM
+to open a datagram socket, and
+.B SOCK_RAW
+to open a
+.BR raw (7)
+socket to access the IP protocol directly.
+.P
+.I protocol
+is the IP protocol in the IP header to be received or sent.
+Valid values for
+.I protocol
+include:
+.IP \[bu] 3
+0 and
+.B IPPROTO_TCP
+for
+.BR tcp (7)
+stream sockets;
+.IP \[bu]
+0 and
+.B IPPROTO_UDP
+for
+.BR udp (7)
+datagram sockets;
+.IP \[bu]
+.B IPPROTO_SCTP
+for
+.BR sctp (7)
+stream sockets; and
+.IP \[bu]
+.B IPPROTO_UDPLITE
+for
+.BR udplite (7)
+datagram sockets.
+.P
+For
+.B SOCK_RAW
+you may specify a valid IANA IP protocol defined in
+RFC\ 1700 assigned numbers.
+.P
+When a process wants to receive new incoming packets or connections, it
+should bind a socket to a local interface address using
+.BR bind (2).
+In this case, only one IP socket may be bound to any given local
+(address, port) pair.
+When
+.B INADDR_ANY
+is specified in the bind call, the socket will be bound to
+.I all
+local interfaces.
+When
+.BR listen (2)
+is called on an unbound socket, the socket is automatically bound
+to a random free port with the local address set to
+.BR INADDR_ANY .
+When
+.BR connect (2)
+is called on an unbound socket, the socket is automatically bound
+to a random free port or to a usable shared port with the local address
+set to
+.BR INADDR_ANY .
+.P
+A TCP local socket address that has been bound is unavailable for
+some time after closing, unless the
+.B SO_REUSEADDR
+flag has been set.
+Care should be taken when using this flag as it makes TCP less reliable.
+.SS Address format
+An IP socket address is defined as a combination of an IP interface
+address and a 16-bit port number.
+The basic IP protocol does not supply port numbers, they
+are implemented by higher level protocols like
+.BR udp (7)
+and
+.BR tcp (7).
+On raw sockets
+.I sin_port
+is set to the IP protocol.
+.P
+.in +4n
+.EX
+struct sockaddr_in {
+    sa_family_t    sin_family; /* address family: AF_INET */
+    in_port_t      sin_port;   /* port in network byte order */
+    struct in_addr sin_addr;   /* internet address */
+};
+\&
+/* Internet address */
+struct in_addr {
+    uint32_t       s_addr;     /* address in network byte order */
+};
+.EE
+.in
+.P
+.I sin_family
+is always set to
+.BR AF_INET .
+This is required; in Linux 2.2 most networking functions return
+.B EINVAL
+when this setting is missing.
+.I sin_port
+contains the port in network byte order.
+The port numbers below 1024 are called
+.I privileged ports
+(or sometimes:
+.IR "reserved ports" ).
+Only a privileged process
+(on Linux: a process that has the
+.B CAP_NET_BIND_SERVICE
+capability in the user namespace governing its network namespace) may
+.BR bind (2)
+to these sockets.
+Note that the raw IPv4 protocol as such has no concept of a
+port, they are implemented only by higher protocols like
+.BR tcp (7)
+and
+.BR udp (7).
+.P
+.I sin_addr
+is the IP host address.
+The
+.I s_addr
+member of
+.I struct in_addr
+contains the host interface address in network byte order.
+.I in_addr
+should be assigned one of the
+.B INADDR_*
+values
+(e.g.,
+.BR INADDR_LOOPBACK )
+using
+.BR htonl (3)
+or set using the
+.BR inet_aton (3),
+.BR inet_addr (3),
+.BR inet_makeaddr (3)
+library functions or directly with the name resolver (see
+.BR gethostbyname (3)).
+.P
+IPv4 addresses are divided into unicast, broadcast,
+and multicast addresses.
+Unicast addresses specify a single interface of a host,
+broadcast addresses specify all hosts on a network, and multicast
+addresses address all hosts in a multicast group.
+Datagrams to broadcast addresses can be sent or received only when the
+.B SO_BROADCAST
+socket flag is set.
+In the current implementation, connection-oriented sockets are allowed
+to use only unicast addresses.
+.\" Leave a loophole for XTP @)
+.P
+Note that the address and the port are always stored in
+network byte order.
+In particular, this means that you need to call
+.BR htons (3)
+on the number that is assigned to a port.
+All address/port manipulation
+functions in the standard library work in network byte order.
+.SS Special and reserved addresses
+There are several special addresses:
+.TP
+.BR INADDR_LOOPBACK " (127.0.0.1)"
+always refers to the local host via the loopback device;
+.TP
+.BR INADDR_ANY " (0.0.0.0)"
+means any address for socket binding;
+.TP
+.BR INADDR_BROADCAST " (255.255.255.255)"
+has the same effect on
+.BR bind (2)
+as
+.B INADDR_ANY
+for historical reasons.
+A packet addressed to
+.B INADDR_BROADCAST
+through a socket which has
+.B SO_BROADCAST
+set will be broadcast to all hosts on the local network segment,
+as long as the link is broadcast-capable.
+.TP
+Highest-numbered address
+.TQ
+Lowest-numbered address
+On any locally-attached non-point-to-point IP subnet
+with a link type that supports broadcasts,
+the highest-numbered address
+(e.g., the .255 address on a subnet with netmask 255.255.255.0)
+is designated as a broadcast address.
+It cannot usefully be assigned to an individual interface,
+and can only be addressed with a socket on which the
+.B SO_BROADCAST
+option has been set.
+Internet standards have historically
+also reserved the lowest-numbered address
+(e.g., the .0 address on a subnet with netmask 255.255.255.0)
+for broadcast, though they call it "obsolete" for this purpose.
+(Some sources also refer to this as the "network address.")
+Since Linux 5.14,
+.\" commit 58fee5fc83658aaacf60246aeab738946a9ba516
+it is treated as an ordinary unicast address
+and can be assigned to an interface.
+.P
+Internet standards have traditionally also reserved various addresses
+for particular uses, though Linux no longer treats
+some of these specially.
+.TP
+[0.0.0.1, 0.255.255.255]
+.TQ
+[240.0.0.0, 255.255.255.254]
+Addresses in these ranges (0/8 and 240/4) are reserved globally.
+Since Linux 5.3
+.\" commit 96125bf9985a75db00496dd2bc9249b777d2b19b
+and Linux 2.6.25,
+.\" commit 1e637c74b0f84eaca02b914c0b8c6f67276e9697
+respectively,
+the 0/8 and 240/4 addresses, other than
+.B INADDR_ANY
+and
+.BR INADDR_BROADCAST ,
+are treated as ordinary unicast addresses.
+Systems that follow the traditional behaviors may not
+interoperate with these historically reserved addresses.
+.TP
+[127.0.0.1, 127.255.255.254]
+Addresses in this range (127/8) are treated as loopback addresses
+akin to the standardized local loopback address
+.B INADDR_LOOPBACK
+(127.0.0.1);
+.TP
+[224.0.0.0, 239.255.255.255]
+Addresses in this range (224/4) are dedicated to multicast use.
+.SS Socket options
+IP supports some protocol-specific socket options that can be set with
+.BR setsockopt (2)
+and read with
+.BR getsockopt (2).
+The socket option level for IP is
+.BR IPPROTO_IP .
+.\" or SOL_IP on Linux
+A boolean integer flag is zero when it is false, otherwise true.
+.P
+When an invalid socket option is specified,
+.BR getsockopt (2)
+and
+.BR setsockopt (2)
+fail with the error
+.BR ENOPROTOOPT .
+.TP
+.BR IP_ADD_MEMBERSHIP " (since Linux 1.2)"
+Join a multicast group.
+Argument is an
+.I ip_mreqn
+structure.
+.IP
+.in +4n
+.EX
+struct ip_mreqn {
+    struct in_addr imr_multiaddr; /* IP multicast group
+                                     address */
+    struct in_addr imr_address;   /* IP address of local
+                                     interface */
+    int            imr_ifindex;   /* interface index */
+};
+.EE
+.in
+.IP
+.I imr_multiaddr
+contains the address of the multicast group the application
+wants to join or leave.
+It must be a valid multicast address
+.\" (i.e., within the 224.0.0.0-239.255.255.255 range)
+(or
+.BR setsockopt (2)
+fails with the error
+.BR EINVAL ).
+.I imr_address
+is the address of the local interface with which the system
+should join the multicast group; if it is equal to
+.BR INADDR_ANY ,
+an appropriate interface is chosen by the system.
+.I imr_ifindex
+is the interface index of the interface that should join/leave the
+.I imr_multiaddr
+group, or 0 to indicate any interface.
+.IP
+The
+.I ip_mreqn
+structure is available only since Linux 2.2.
+For compatibility, the old
+.I ip_mreq
+structure (present since Linux 1.2) is still supported;
+it differs from
+.I ip_mreqn
+only by not including the
+.I imr_ifindex
+field.
+(The kernel determines which structure is being passed based
+on the size passed in
+.IR optlen .)
+.IP
+.B IP_ADD_MEMBERSHIP
+is valid only for
+.BR setsockopt (2).
+.\"
+.TP
+.BR IP_ADD_SOURCE_MEMBERSHIP " (since Linux 2.4.22 / Linux 2.5.68)"
+Join a multicast group and allow receiving data only
+from a specified source.
+Argument is an
+.I ip_mreq_source
+structure.
+.IP
+.in +4n
+.EX
+struct ip_mreq_source {
+    struct in_addr imr_multiaddr;  /* IP multicast group
+                                      address */
+    struct in_addr imr_interface;  /* IP address of local
+                                      interface */
+    struct in_addr imr_sourceaddr; /* IP address of
+                                      multicast source */
+};
+.EE
+.in
+.IP
+The
+.I ip_mreq_source
+structure is similar to
+.I ip_mreqn
+described under
+.BR IP_ADD_MEMBERSHIP .
+The
+.I imr_multiaddr
+field contains the address of the multicast group the application
+wants to join or leave.
+The
+.I imr_interface
+field is the address of the local interface with which
+the system should join the multicast group.
+Finally, the
+.I imr_sourceaddr
+field contains the address of the source the
+application wants to receive data from.
+.IP
+This option can be used multiple times to allow
+receiving data from more than one source.
+.TP
+.BR IP_BIND_ADDRESS_NO_PORT " (since Linux 4.2)"
+.\" commit 90c337da1524863838658078ec34241f45d8394d
+Inform the kernel to not reserve an ephemeral port when using
+.BR bind (2)
+with a port number of 0.
+The port will later be automatically chosen at
+.BR connect (2)
+time,
+in a way that allows sharing a source port as long as the 4-tuple is unique.
+.TP
+.BR IP_BLOCK_SOURCE " (since Linux 2.4.22 / 2.5.68)"
+Stop receiving multicast data from a specific source in a given group.
+This is valid only after the application has subscribed
+to the multicast group using either
+.B IP_ADD_MEMBERSHIP
+or
+.BR IP_ADD_SOURCE_MEMBERSHIP .
+.IP
+Argument is an
+.I ip_mreq_source
+structure as described under
+.BR IP_ADD_SOURCE_MEMBERSHIP .
+.TP
+.BR IP_DROP_MEMBERSHIP " (since Linux 1.2)"
+Leave a multicast group.
+Argument is an
+.I ip_mreqn
+or
+.I ip_mreq
+structure similar to
+.BR IP_ADD_MEMBERSHIP .
+.TP
+.BR IP_DROP_SOURCE_MEMBERSHIP " (since Linux 2.4.22 / 2.5.68)"
+Leave a source-specific group\[em]that is, stop receiving data from
+a given multicast group that come from a given source.
+If the application has subscribed to multiple sources within
+the same group, data from the remaining sources will still be delivered.
+To stop receiving data from all sources at once, use
+.BR IP_DROP_MEMBERSHIP .
+.IP
+Argument is an
+.I ip_mreq_source
+structure as described under
+.BR IP_ADD_SOURCE_MEMBERSHIP .
+.TP
+.BR IP_FREEBIND " (since Linux 2.4)"
+.\" Precisely: since Linux 2.4.0-test10
+If enabled, this boolean option allows binding to an IP address
+that is nonlocal or does not (yet) exist.
+This permits listening on a socket,
+without requiring the underlying network interface or the
+specified dynamic IP address to be up at the time that
+the application is trying to bind to it.
+This option is the per-socket equivalent of the
+.I ip_nonlocal_bind
+.I /proc
+interface described below.
+.TP
+.BR IP_HDRINCL " (since Linux 2.0)"
+If enabled,
+the user supplies an IP header in front of the user data.
+Valid only for
+.B SOCK_RAW
+sockets; see
+.BR raw (7)
+for more information.
+When this flag is enabled, the values set by
+.BR IP_OPTIONS ,
+.BR IP_TTL ,
+and
+.B IP_TOS
+are ignored.
+.TP
+.BR IP_LOCAL_PORT_RANGE " (since Linux 6.3)"
+Set or get the per-socket default local port range.
+This option can be used to clamp down the global local port range,
+defined by the
+.I ip_local_port_range
+.I /proc
+interface described below, for a given socket.
+.IP
+The option takes an
+.I uint32_t
+value with
+the high 16 bits set to the upper range bound,
+and the low 16 bits set to the lower range bound.
+Range bounds are inclusive.
+The 16-bit values should be in host byte order.
+.IP
+The lower bound has to be less than the upper bound
+when both bounds are not zero.
+Otherwise, setting the option fails with EINVAL.
+.IP
+If either bound is outside of the global local port range, or is zero,
+then that bound has no effect.
+.IP
+To reset the setting,
+pass zero as both the upper and the lower bound.
+.TP
+.BR IP_MSFILTER " (since Linux 2.4.22 / 2.5.68)"
+This option provides access to the advanced full-state filtering API.
+Argument is an
+.I ip_msfilter
+structure.
+.IP
+.in +4n
+.EX
+struct ip_msfilter {
+    struct in_addr imsf_multiaddr; /* IP multicast group
+                                      address */
+    struct in_addr imsf_interface; /* IP address of local
+                                      interface */
+    uint32_t       imsf_fmode;     /* Filter\-mode */
+\&
+    uint32_t       imsf_numsrc;    /* Number of sources in
+                                      the following array */
+    struct in_addr imsf_slist[1];  /* Array of source
+                                      addresses */
+};
+.EE
+.in
+.IP
+There are two macros,
+.B MCAST_INCLUDE
+and
+.BR MCAST_EXCLUDE ,
+which can be used to specify the filtering mode.
+Additionally, the
+.BR IP_MSFILTER_SIZE (n)
+macro exists to determine how much memory is needed to store
+.I ip_msfilter
+structure with
+.I n
+sources in the source list.
+.IP
+For the full description of multicast source filtering
+refer to RFC 3376.
+.TP
+.BR IP_MTU " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.124
+Retrieve the current known path MTU of the current socket.
+Returns an integer.
+.IP
+.B IP_MTU
+is valid only for
+.BR getsockopt (2)
+and can be employed only when the socket has been connected.
+.TP
+.BR IP_MTU_DISCOVER " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.124
+Set or receive the Path MTU Discovery setting for a socket.
+When enabled, Linux will perform Path MTU Discovery
+as defined in RFC\ 1191 on
+.B SOCK_STREAM
+sockets.
+For
+.RB non- SOCK_STREAM
+sockets,
+.B IP_PMTUDISC_DO
+forces the don't-fragment flag to be set on all outgoing packets.
+It is the user's responsibility to packetize the data
+in MTU-sized chunks and to do the retransmits if necessary.
+The kernel will reject (with
+.BR EMSGSIZE )
+datagrams that are bigger than the known path MTU.
+.B IP_PMTUDISC_WANT
+will fragment a datagram if needed according to the path MTU,
+or will set the don't-fragment flag otherwise.
+.IP
+The system-wide default can be toggled between
+.B IP_PMTUDISC_WANT
+and
+.B IP_PMTUDISC_DONT
+by writing (respectively, zero and nonzero values) to the
+.I /proc/sys/net/ipv4/ip_no_pmtu_disc
+file.
+.TS
+tab(:);
+c l
+l l.
+Path MTU discovery value:Meaning
+IP_PMTUDISC_WANT:Use per-route settings.
+IP_PMTUDISC_DONT:Never do Path MTU Discovery.
+IP_PMTUDISC_DO:Always do Path MTU Discovery.
+IP_PMTUDISC_PROBE:Set DF but ignore Path MTU.
+.TE
+.IP
+When PMTU discovery is enabled, the kernel automatically keeps track of
+the path MTU per destination host.
+When it is connected to a specific peer with
+.BR connect (2),
+the currently known path MTU can be retrieved conveniently using the
+.B IP_MTU
+socket option (e.g., after an
+.B EMSGSIZE
+error occurred).
+The path MTU may change over time.
+For connectionless sockets with many destinations,
+the new MTU for a given destination can also be accessed using the
+error queue (see
+.BR IP_RECVERR ).
+A new error will be queued for every incoming MTU update.
+.IP
+While MTU discovery is in progress, initial packets from datagram sockets
+may be dropped.
+Applications using UDP should be aware of this and not
+take it into account for their packet retransmit strategy.
+.IP
+To bootstrap the path MTU discovery process on unconnected sockets, it
+is possible to start with a big datagram size
+(headers up to 64 kilobytes long) and let it shrink by updates of the path MTU.
+.IP
+To get an initial estimate of the
+path MTU, connect a datagram socket to the destination address using
+.BR connect (2)
+and retrieve the MTU by calling
+.BR getsockopt (2)
+with the
+.B IP_MTU
+option.
+.IP
+It is possible to implement RFC 4821 MTU probing with
+.B SOCK_DGRAM
+or
+.B SOCK_RAW
+sockets by setting a value of
+.B IP_PMTUDISC_PROBE
+(available since Linux 2.6.22).
+This is also particularly useful for diagnostic tools such as
+.BR tracepath (8)
+that wish to deliberately send probe packets larger than
+the observed Path MTU.
+.TP
+.BR IP_MULTICAST_ALL " (since Linux 2.6.31)"
+This option can be used to modify the delivery policy of multicast messages.
+The argument is a boolean integer (defaults to 1).
+If set to 1,
+the socket will receive messages from all the groups that have been joined
+globally on the whole system.
+Otherwise, it will deliver messages only from
+the groups that have been explicitly joined (for example via the
+.B IP_ADD_MEMBERSHIP
+option) on this particular socket.
+.TP
+.BR IP_MULTICAST_IF " (since Linux 1.2)"
+Set the local device for a multicast socket.
+The argument for
+.BR setsockopt (2)
+is an
+.I ip_mreqn
+or
+.\" net: IP_MULTICAST_IF setsockopt now recognizes struct mreq
+.\" Commit: 3a084ddb4bf299a6e898a9a07c89f3917f0713f7
+(since Linux 3.5)
+.I ip_mreq
+structure similar to
+.BR IP_ADD_MEMBERSHIP ,
+or an
+.I in_addr
+structure.
+(The kernel determines which structure is being passed based
+on the size passed in
+.IR optlen .)
+For
+.BR getsockopt (2),
+the argument is an
+.I in_addr
+structure.
+.TP
+.BR IP_MULTICAST_LOOP " (since Linux 1.2)"
+Set or read a boolean integer argument that determines whether
+sent multicast packets should be looped back to the local sockets.
+.TP
+.BR IP_MULTICAST_TTL " (since Linux 1.2)"
+Set or read the time-to-live value of outgoing multicast packets for this
+socket.
+It is very important for multicast packets to set the smallest TTL possible.
+The default is 1 which means that multicast packets don't leave the local
+network unless the user program explicitly requests it.
+Argument is an integer.
+.TP
+.BR IP_NODEFRAG " (since Linux 2.6.36)"
+If enabled (argument is nonzero),
+the reassembly of outgoing packets is disabled in the netfilter layer.
+The argument is an integer.
+.IP
+This option is valid only for
+.B SOCK_RAW
+sockets.
+.TP
+.BR IP_OPTIONS " (since Linux 2.0)"
+.\" Precisely: since Linux 1.3.30
+Set or get the IP options to be sent with every packet from this socket.
+The arguments are a pointer to a memory buffer containing the options
+and the option length.
+The
+.BR setsockopt (2)
+call sets the IP options associated with a socket.
+The maximum option size for IPv4 is 40 bytes.
+See RFC\ 791 for the allowed options.
+When the initial connection request packet for a
+.B SOCK_STREAM
+socket contains IP options, the IP options will be set automatically
+to the options from the initial packet with routing headers reversed.
+Incoming packets are not allowed to change options after the connection
+is established.
+The processing of all incoming source routing options
+is disabled by default and can be enabled by using the
+.I accept_source_route
+.I /proc
+interface.
+Other options like timestamps are still handled.
+For datagram sockets, IP options can be set only by the local user.
+Calling
+.BR getsockopt (2)
+with
+.B IP_OPTIONS
+puts the current IP options used for sending into the supplied buffer.
+.TP
+.BR IP_PASSSEC " (since Linux 2.6.17)"
+.\" commit 2c7946a7bf45ae86736ab3b43d0085e43947945c
+If labeled IPSEC or NetLabel is configured on the sending and receiving
+hosts, this option enables receiving of the security context of the peer
+socket in an ancillary message of type
+.B SCM_SECURITY
+retrieved using
+.BR recvmsg (2).
+This option is supported only for UDP sockets; for TCP or SCTP sockets,
+see the description of the
+.B SO_PEERSEC
+option below.
+.IP
+The value given as an argument to
+.BR setsockopt (2)
+and returned as the result of
+.BR getsockopt (2)
+is an integer boolean flag.
+.IP
+The security context returned in the
+.B SCM_SECURITY
+ancillary message
+is of the same format as the one described under the
+.B SO_PEERSEC
+option below.
+.IP
+Note: the reuse of the
+.B SCM_SECURITY
+message type for the
+.B IP_PASSSEC
+socket option was likely a mistake, since other IP control messages use
+their own numbering scheme in the IP namespace and often use the
+socket option value as the message type.
+There is no conflict currently since the IP option with the same value as
+.B SCM_SECURITY
+is
+.B IP_HDRINCL
+and this is never used for a control message type.
+.TP
+.BR IP_PKTINFO " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.68
+Pass an
+.B IP_PKTINFO
+ancillary message that contains a
+.I pktinfo
+structure that supplies some information about the incoming packet.
+This works only for datagram oriented sockets.
+The argument is a flag that tells the socket whether the
+.B IP_PKTINFO
+message should be passed or not.
+The message itself can be sent/retrieved
+only as a control message with a packet using
+.BR recvmsg (2)
+or
+.BR sendmsg (2).
+.IP
+.in +4n
+.EX
+struct in_pktinfo {
+    unsigned int   ipi_ifindex;  /* Interface index */
+    struct in_addr ipi_spec_dst; /* Local address */
+    struct in_addr ipi_addr;     /* Header Destination
+                                    address */
+};
+.EE
+.in
+.IP
+.I ipi_ifindex
+is the unique index of the interface the packet was received on.
+.I ipi_spec_dst
+is the local address of the packet and
+.I ipi_addr
+is the destination address in the packet header.
+If
+.B IP_PKTINFO
+is passed to
+.BR sendmsg (2)
+and
+.\" This field is grossly misnamed
+.I ipi_spec_dst
+is not zero, then it is used as the local source address for the routing
+table lookup and for setting up IP source route options.
+When
+.I ipi_ifindex
+is not zero, the primary local address of the interface specified by the
+index overwrites
+.I ipi_spec_dst
+for the routing table lookup.
+.IP
+Not supported for
+.B SOCK_STREAM
+sockets.
+.TP
+.BR IP_RECVERR " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.15
+Enable extended reliable error message passing.
+When enabled on a datagram socket, all
+generated errors will be queued in a per-socket error queue.
+When the user receives an error from a socket operation,
+the errors can be received by calling
+.BR recvmsg (2)
+with the
+.B MSG_ERRQUEUE
+flag set.
+The
+.I sock_extended_err
+structure describing the error will be passed in an ancillary message with
+the type
+.B IP_RECVERR
+and the level
+.BR IPPROTO_IP .
+.\" or SOL_IP on Linux
+This is useful for reliable error handling on unconnected sockets.
+The received data portion of the error queue contains the error packet.
+.IP
+The
+.B IP_RECVERR
+control message contains a
+.I sock_extended_err
+structure:
+.IP
+.in +4n
+.EX
+#define SO_EE_ORIGIN_NONE    0
+#define SO_EE_ORIGIN_LOCAL   1
+#define SO_EE_ORIGIN_ICMP    2
+#define SO_EE_ORIGIN_ICMP6   3
+\&
+struct sock_extended_err {
+    uint32_t ee_errno;   /* error number */
+    uint8_t  ee_origin;  /* where the error originated */
+    uint8_t  ee_type;    /* type */
+    uint8_t  ee_code;    /* code */
+    uint8_t  ee_pad;
+    uint32_t ee_info;    /* additional information */
+    uint32_t ee_data;    /* other data */
+    /* More data may follow */
+};
+\&
+struct sockaddr *SO_EE_OFFENDER(struct sock_extended_err *);
+.EE
+.in
+.IP
+.I ee_errno
+contains the
+.I errno
+number of the queued error.
+.I ee_origin
+is the origin code of where the error originated.
+The other fields are protocol-specific.
+The macro
+.B SO_EE_OFFENDER
+returns a pointer to the address of the network object
+where the error originated from given a pointer to the ancillary message.
+If this address is not known, the
+.I sa_family
+member of the
+.I sockaddr
+contains
+.B AF_UNSPEC
+and the other fields of the
+.I sockaddr
+are undefined.
+.IP
+IP uses the
+.I sock_extended_err
+structure as follows:
+.I ee_origin
+is set to
+.B SO_EE_ORIGIN_ICMP
+for errors received as an ICMP packet, or
+.B SO_EE_ORIGIN_LOCAL
+for locally generated errors.
+Unknown values should be ignored.
+.I ee_type
+and
+.I ee_code
+are set from the type and code fields of the ICMP header.
+.I ee_info
+contains the discovered MTU for
+.B EMSGSIZE
+errors.
+The message also contains the
+.I sockaddr_in of the node
+caused the error, which can be accessed with the
+.B SO_EE_OFFENDER
+macro.
+The
+.I sin_family
+field of the
+.B SO_EE_OFFENDER
+address is
+.B AF_UNSPEC
+when the source was unknown.
+When the error originated from the network, all IP options
+.RB ( IP_OPTIONS ", " IP_TTL ,
+etc.) enabled on the socket and contained in the
+error packet are passed as control messages.
+The payload of the packet causing the error is returned as normal payload.
+.\" FIXME . Is it a good idea to document that? It is a dubious feature.
+.\" On
+.\" .B SOCK_STREAM
+.\" sockets,
+.\" .B IP_RECVERR
+.\" has slightly different semantics. Instead of
+.\" saving the errors for the next timeout, it passes all incoming
+.\" errors immediately to the user.
+.\" This might be useful for very short-lived TCP connections which
+.\" need fast error handling. Use this option with care:
+.\" it makes TCP unreliable
+.\" by not allowing it to recover properly from routing
+.\" shifts and other normal
+.\" conditions and breaks the protocol specification.
+Note that TCP has no error queue;
+.B MSG_ERRQUEUE
+is not permitted on
+.B SOCK_STREAM
+sockets.
+.B IP_RECVERR
+is valid for TCP, but all errors are returned by socket function return or
+.B SO_ERROR
+only.
+.IP
+For raw sockets,
+.B IP_RECVERR
+enables passing of all received ICMP errors to the
+application, otherwise errors are reported only on connected sockets
+.IP
+It sets or retrieves an integer boolean flag.
+.B IP_RECVERR
+defaults to off.
+.TP
+.BR IP_RECVOPTS " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.15
+Pass all incoming IP options to the user in a
+.B IP_OPTIONS
+control message.
+The routing header and other options are already filled in
+for the local host.
+Not supported for
+.B SOCK_STREAM
+sockets.
+.TP
+.BR IP_RECVORIGDSTADDR " (since Linux 2.6.29)"
+.\" commit e8b2dfe9b4501ed0047459b2756ba26e5a940a69
+This boolean option enables the
+.B IP_ORIGDSTADDR
+ancillary message in
+.BR recvmsg (2),
+in which the kernel returns the original destination address
+of the datagram being received.
+The ancillary message contains a
+.IR "struct sockaddr_in" .
+Not supported for
+.B SOCK_STREAM
+sockets.
+.TP
+.BR IP_RECVTOS " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.68
+If enabled, the
+.B IP_TOS
+ancillary message is passed with incoming packets.
+It contains a byte which specifies the Type of Service/Precedence
+field of the packet header.
+Expects a boolean integer flag.
+Not supported for
+.B SOCK_STREAM
+sockets.
+.TP
+.BR IP_RECVTTL " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.68
+When this flag is set, pass a
+.B IP_TTL
+control message with the time-to-live
+field of the received packet as a 32 bit integer.
+Not supported for
+.B SOCK_STREAM
+sockets.
+.TP
+.BR IP_RETOPTS " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.15
+Identical to
+.BR IP_RECVOPTS ,
+but returns raw unprocessed options with timestamp and route record
+options not filled in for this hop.
+Not supported for
+.B SOCK_STREAM
+sockets.
+.TP
+.BR IP_ROUTER_ALERT " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.68
+Pass all to-be forwarded packets with the
+IP Router Alert option set to this socket.
+Valid only for raw sockets.
+This is useful, for instance, for user-space RSVP daemons.
+The tapped packets are not forwarded by the kernel; it is
+the user's responsibility to send them out again.
+Socket binding is ignored,
+such packets are filtered only by protocol.
+Expects an integer flag.
+.TP
+.BR IP_TOS " (since Linux 1.0)"
+Set or receive the Type-Of-Service (TOS) field that is sent
+with every IP packet originating from this socket.
+It is used to prioritize packets on the network.
+TOS is a byte.
+There are some standard TOS flags defined:
+.B IPTOS_LOWDELAY
+to minimize delays for interactive traffic,
+.B IPTOS_THROUGHPUT
+to optimize throughput,
+.B IPTOS_RELIABILITY
+to optimize for reliability,
+.B IPTOS_MINCOST
+should be used for "filler data" where slow transmission doesn't matter.
+At most one of these TOS values can be specified.
+Other bits are invalid and shall be cleared.
+Linux sends
+.B IPTOS_LOWDELAY
+datagrams first by default,
+but the exact behavior depends on the configured queueing discipline.
+.\" FIXME elaborate on this
+Some high-priority levels may require superuser privileges (the
+.B CAP_NET_ADMIN
+capability).
+.\" The priority can also be set in a protocol-independent way by the
+.\" .RB ( SOL_SOCKET ", " SO_PRIORITY )
+.\" socket option (see
+.\" .BR socket (7)).
+.TP
+.BR IP_TRANSPARENT " (since Linux 2.6.24)"
+.\" commit f5715aea4564f233767ea1d944b2637a5fd7cd2e
+.\"     This patch introduces the IP_TRANSPARENT socket option: enabling that
+.\"     will make the IPv4 routing omit the non-local source address check on
+.\"     output. Setting IP_TRANSPARENT requires NET_ADMIN capability.
+.\" http://lwn.net/Articles/252545/
+Setting this boolean option enables transparent proxying on this socket.
+This socket option allows
+the calling application to bind to a nonlocal IP address and operate
+both as a client and a server with the foreign address as the local endpoint.
+NOTE: this requires that routing be set up in a way that
+packets going to the foreign address are routed through the TProxy box
+(i.e., the system hosting the application that employs the
+.B IP_TRANSPARENT
+socket option).
+Enabling this socket option requires superuser privileges
+(the
+.B CAP_NET_ADMIN
+capability).
+.IP
+TProxy redirection with the iptables TPROXY target also requires that
+this option be set on the redirected socket.
+.TP
+.BR IP_TTL " (since Linux 1.0)"
+Set or retrieve the current time-to-live field that is used in every packet
+sent from this socket.
+.TP
+.BR IP_UNBLOCK_SOURCE " (since Linux 2.4.22 / 2.5.68)"
+Unblock previously blocked multicast source.
+Returns
+.B EADDRNOTAVAIL
+when given source is not being blocked.
+.IP
+Argument is an
+.I ip_mreq_source
+structure as described under
+.BR IP_ADD_SOURCE_MEMBERSHIP .
+.TP
+.BR SO_PEERSEC " (since Linux 2.6.17)"
+If labeled IPSEC or NetLabel is configured on both the sending and
+receiving hosts, this read-only socket option returns the security
+context of the peer socket connected to this socket.
+By default,
+this will be the same as the security context of the process that created
+the peer socket unless overridden by the policy or by a process with
+the required permissions.
+.IP
+The argument to
+.BR getsockopt (2)
+is a pointer to a buffer of the specified length in bytes
+into which the security context string will be copied.
+If the buffer length is less than the length of the security
+context string, then
+.BR getsockopt (2)
+returns \-1, sets
+.I errno
+to
+.BR ERANGE ,
+and returns the required length via
+.IR optlen .
+The caller should allocate at least
+.B NAME_MAX
+bytes for the buffer initially, although this is not guaranteed
+to be sufficient.
+Resizing the buffer to the returned length
+and retrying may be necessary.
+.IP
+The security context string may include a terminating null character
+in the returned length, but is not guaranteed to do so: a security
+context "foo" might be represented as either {'f','o','o'} of length 3
+or {'f','o','o','\\0'} of length 4, which are considered to be
+interchangeable.
+The string is printable, does not contain non-terminating null characters,
+and is in an unspecified encoding (in particular, it
+is not guaranteed to be ASCII or UTF-8).
+.IP
+The use of this option for sockets in the
+.B AF_INET
+address family is supported since Linux 2.6.17
+.\" commit 2c7946a7bf45ae86736ab3b43d0085e43947945c
+for TCP sockets, and since Linux 4.17
+.\" commit d452930fd3b9031e59abfeddb2fa383f1403d61a
+for SCTP sockets.
+.IP
+For SELinux, NetLabel conveys only the MLS portion of the security
+context of the peer across the wire, defaulting the rest of the
+security context to the values defined in the policy for the
+netmsg initial security identifier (SID).
+However, NetLabel can
+be configured to pass full security contexts over loopback.
+Labeled IPSEC always passes full security contexts as part of establishing
+the security association (SA) and looks them up based on the association
+for each packet.
+.\"
+.SS /proc interfaces
+The IP protocol
+supports a set of
+.I /proc
+interfaces to configure some global parameters.
+The parameters can be accessed by reading or writing files in the directory
+.IR /proc/sys/net/ipv4/ .
+.\" FIXME As at 2.6.12, 14 Jun 2005, the following are undocumented:
+.\"  ip_queue_maxlen
+.\"  ip_conntrack_max
+Interfaces described as
+.I Boolean
+take an integer value, with a nonzero value ("true") meaning that
+the corresponding option is enabled, and a zero value ("false")
+meaning that the option is disabled.
+.\"
+.TP
+.IR ip_always_defrag " (Boolean; since Linux 2.2.13)"
+[New with Linux 2.2.13; in earlier kernel versions this feature
+was controlled at compile time by the
+.B CONFIG_IP_ALWAYS_DEFRAG
+option; this option is not present in Linux 2.4.x and later]
+.IP
+When this boolean flag is enabled (not equal 0), incoming fragments
+(parts of IP packets
+that arose when some host between origin and destination decided
+that the packets were too large and cut them into pieces) will be
+reassembled (defragmented) before being processed, even if they are
+about to be forwarded.
+.IP
+Enable only if running either a firewall that is the sole link
+to your network or a transparent proxy; never ever use it for a
+normal router or host.
+Otherwise, fragmented communication can be disturbed
+if the fragments travel over different links.
+Defragmentation also has a large memory and CPU time cost.
+.IP
+This is automagically turned on when masquerading or transparent
+proxying are configured.
+.\"
+.TP
+.IR ip_autoconfig " (since Linux 2.2 to Linux 2.6.17)"
+.\" Precisely: since Linux 2.1.68
+.\" FIXME document ip_autoconfig
+Not documented.
+.\"
+.TP
+.IR ip_default_ttl " (integer; default: 64; since Linux 2.2)"
+.\" Precisely: since Linux 2.1.15
+Set the default time-to-live value of outgoing packets.
+This can be changed per socket with the
+.B IP_TTL
+option.
+.\"
+.TP
+.IR ip_dynaddr " (Boolean; default: disabled; since Linux 2.0.31)"
+Enable dynamic socket address and masquerading entry rewriting on interface
+address change.
+This is useful for dialup interface with changing IP addresses.
+0 means no rewriting, 1 turns it on and 2 enables verbose mode.
+.\"
+.TP
+.IR ip_forward " (Boolean; default: disabled; since Linux 1.2)"
+Enable IP forwarding with a boolean flag.
+IP forwarding can be also set on a per-interface basis.
+.\"
+.TP
+.IR ip_local_port_range " (since Linux 2.2)"
+.\" Precisely: since Linux 2.1.68
+This file contains two integers that define the default local port range
+allocated to sockets that are not explicitly bound to a port number\[em]that
+is, the range used for
+.IR "ephemeral ports" .
+An ephemeral port is allocated to a socket in the following circumstances:
+.RS
+.IP \[bu] 3
+the port number in a socket address is specified as 0 when calling
+.BR bind (2);
+.IP \[bu]
+.BR listen (2)
+is called on a stream socket that was not previously bound;
+.IP \[bu]
+.BR connect (2)
+was called on a socket that was not previously bound;
+.IP \[bu]
+.BR sendto (2)
+is called on a datagram socket that was not previously bound.
+.RE
+.IP
+Allocation of ephemeral ports starts with the first number in
+.I ip_local_port_range
+and ends with the second number.
+If the range of ephemeral ports is exhausted,
+then the relevant system call returns an error (but see BUGS).
+.IP
+Note that the port range in
+.I ip_local_port_range
+should not conflict with the ports used by masquerading
+(although the case is handled).
+Also, arbitrary choices may cause problems with some firewall packet
+filters that make assumptions about the local ports in use.
+The first number should be at least greater than 1024,
+or better, greater than 4096, to avoid clashes
+with well known ports and to minimize firewall problems.
+.\"
+.TP
+.IR ip_no_pmtu_disc " (Boolean; default: disabled; since Linux 2.2)"
+.\" Precisely: 2.1.15
+If enabled, don't do Path MTU Discovery for TCP sockets by default.
+Path MTU discovery may fail if misconfigured firewalls (that drop
+all ICMP packets) or misconfigured interfaces (e.g., a point-to-point
+link where the both ends don't agree on the MTU) are on the path.
+It is better to fix the broken routers on the path than to turn off
+Path MTU Discovery globally, because not doing it incurs a high cost
+to the network.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR ip_nonlocal_bind " (Boolean; default: disabled; since Linux 2.4)"
+.\" Precisely: patch-2.4.0-test10
+If set, allows processes to
+.BR bind (2)
+to nonlocal IP addresses,
+which can be quite useful, but may break some applications.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR ip6frag_time " (integer; default: 30)"
+Time in seconds to keep an IPv6 fragment in memory.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR ip6frag_secret_interval " (integer; default: 600)"
+Regeneration interval (in seconds) of the hash secret (or lifetime
+for the hash secret) for IPv6 fragments.
+.TP
+.IR ipfrag_high_thresh " (integer)"
+.TQ
+.IR ipfrag_low_thresh " (integer)"
+If the amount of queued IP fragments reaches
+.IR ipfrag_high_thresh ,
+the queue is pruned down to
+.IR ipfrag_low_thresh .
+Contains an integer with the number of bytes.
+.TP
+.I neigh/*
+See
+.BR arp (7).
+.\" FIXME Document the conf/*/* interfaces
+.\"
+.\" FIXME Document the route/* interfaces
+.SS Ioctls
+All ioctls described in
+.BR socket (7)
+apply to
+.BR ip .
+.P
+Ioctls to configure generic device parameters are described in
+.BR netdevice (7).
+.\" FIXME Add a discussion of multicasting
+.SH ERRORS
+.\" FIXME document all errors.
+.\"     We should really fix the kernels to give more uniform
+.\"     error returns (ENOMEM vs ENOBUFS, EPERM vs EACCES etc.)
+.TP
+.B EACCES
+The user tried to execute an operation without the necessary permissions.
+These include:
+sending a packet to a broadcast address without having the
+.B SO_BROADCAST
+flag set;
+sending a packet via a
+.I prohibit
+route;
+modifying firewall settings without superuser privileges (the
+.B CAP_NET_ADMIN
+capability);
+binding to a privileged port without superuser privileges (the
+.B CAP_NET_BIND_SERVICE
+capability).
+.TP
+.B EADDRINUSE
+Tried to bind to an address already in use.
+.TP
+.B EADDRNOTAVAIL
+A nonexistent interface was requested or the requested source
+address was not local.
+.TP
+.B EAGAIN
+Operation on a nonblocking socket would block.
+.TP
+.B EALREADY
+A connection operation on a nonblocking socket is already in progress.
+.TP
+.B ECONNABORTED
+A connection was closed during an
+.BR accept (2).
+.TP
+.B EHOSTUNREACH
+No valid routing table entry matches the destination address.
+This error can be caused by an ICMP message from a remote router or
+for the local routing table.
+.TP
+.B EINVAL
+Invalid argument passed.
+For send operations this can be caused by sending to a
+.I blackhole
+route.
+.TP
+.B EISCONN
+.BR connect (2)
+was called on an already connected socket.
+.TP
+.B EMSGSIZE
+Datagram is bigger than an MTU on the path and it cannot be fragmented.
+.TP
+.B ENOBUFS
+.TQ
+.B ENOMEM
+Not enough free memory.
+This often means that the memory allocation is limited by the socket
+buffer limits, not by the system memory, but this is not 100% consistent.
+.TP
+.B ENOENT
+.B SIOCGSTAMP
+was called on a socket where no packet arrived.
+.TP
+.B ENOPKG
+A kernel subsystem was not configured.
+.TP
+.BR ENOPROTOOPT " and " EOPNOTSUPP
+Invalid socket option passed.
+.TP
+.B ENOTCONN
+The operation is defined only on a connected socket, but the socket wasn't
+connected.
+.TP
+.B EPERM
+User doesn't have permission to set high priority, change configuration,
+or send signals to the requested process or group.
+.TP
+.B EPIPE
+The connection was unexpectedly closed or shut down by the other end.
+.TP
+.B ESOCKTNOSUPPORT
+The socket is not configured or an unknown socket type was requested.
+.P
+Other errors may be generated by the overlaying protocols; see
+.BR tcp (7),
+.BR raw (7),
+.BR udp (7),
+and
+.BR socket (7).
+.SH NOTES
+.BR IP_FREEBIND ,
+.BR IP_MSFILTER ,
+.BR IP_MTU ,
+.BR IP_MTU_DISCOVER ,
+.BR IP_RECVORIGDSTADDR ,
+.BR IP_PASSSEC ,
+.BR IP_PKTINFO ,
+.BR IP_RECVERR ,
+.BR IP_ROUTER_ALERT ,
+and
+.B IP_TRANSPARENT
+are Linux-specific.
+.\" IP_XFRM_POLICY is Linux-specific
+.\" IP_IPSEC_POLICY is a nonstandard extension, also present on some BSDs
+.P
+Be very careful with the
+.B SO_BROADCAST
+option \- it is not privileged in Linux.
+It is easy to overload the network
+with careless broadcasts.
+For new application protocols
+it is better to use a multicast group instead of broadcasting.
+Broadcasting is discouraged.
+See RFC 6762 for an example of a protocol (mDNS)
+using the more modern multicast approach
+to communicating with an open-ended
+group of hosts on the local network.
+.P
+Some other BSD sockets implementations provide
+.B IP_RCVDSTADDR
+and
+.B IP_RECVIF
+socket options to get the destination address and the interface of
+received datagrams.
+Linux has the more general
+.B IP_PKTINFO
+for the same task.
+.P
+Some BSD sockets implementations also provide an
+.B IP_RECVTTL
+option, but an ancillary message with type
+.B IP_RECVTTL
+is passed with the incoming packet.
+This is different from the
+.B IP_TTL
+option used in Linux.
+.P
+Using the
+.B SOL_IP
+socket options level isn't portable; BSD-based stacks use the
+.B IPPROTO_IP
+level.
+.P
+.B INADDR_ANY
+(0.0.0.0) and
+.B INADDR_BROADCAST
+(255.255.255.255) are byte-order-neutral.
+This means
+.BR htonl (3)
+has no effect on them.
+.SS Compatibility
+For compatibility with Linux 2.0, the obsolete
+.BI "socket(AF_INET, SOCK_PACKET, " protocol )
+syntax is still supported to open a
+.BR packet (7)
+socket.
+This is deprecated and should be replaced by
+.BI "socket(AF_PACKET, SOCK_RAW, " protocol )
+instead.
+The main difference is the new
+.I sockaddr_ll
+address structure for generic link layer information instead of the old
+.BR sockaddr_pkt .
+.SH BUGS
+There are too many inconsistent error values.
+.P
+The error used to diagnose exhaustion of the ephemeral port range differs
+across the various system calls
+.RB ( connect (2),
+.BR bind (2),
+.BR listen (2),
+.BR sendto (2))
+that can assign ephemeral ports.
+.P
+The ioctls to configure IP-specific interface options and ARP tables are
+not described.
+.\" .P
+.\" Some versions of glibc forget to declare
+.\" .IR in_pktinfo .
+.\" Workaround currently is to copy it into your program from this man page.
+.P
+Receiving the original destination address with
+.B MSG_ERRQUEUE
+in
+.I msg_name
+by
+.BR recvmsg (2)
+does not work in some Linux 2.2 kernels.
+.\" .SH AUTHORS
+.\" This man page was written by Andi Kleen.
+.SH SEE ALSO
+.BR recvmsg (2),
+.BR sendmsg (2),
+.BR byteorder (3),
+.BR capabilities (7),
+.BR icmp (7),
+.BR ipv6 (7),
+.BR netdevice (7),
+.BR netlink (7),
+.BR raw (7),
+.BR socket (7),
+.BR tcp (7),
+.BR udp (7),
+.BR ip (8)
+.P
+The kernel source file
+.IR Documentation/networking/ip\-sysctl.txt .
+.P
+RFC\ 791 for the original IP specification.
+RFC\ 1122 for the IPv4 host requirements.
+RFC\ 1812 for the IPv4 router requirements.
diff --git a/man/man7/ipc_namespaces.7 b/man/man7/ipc_namespaces.7
new file mode 100644
index 000000000..77d8c5ebb
--- /dev/null
+++ b/man/man7/ipc_namespaces.7
@@ -0,0 +1,66 @@
+.\" Copyright (c) 2019 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH ipc_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ipc_namespaces \- overview of Linux IPC namespaces
+.SH DESCRIPTION
+IPC namespaces isolate certain IPC resources,
+namely, System V IPC objects (see
+.BR sysvipc (7))
+and (since Linux 2.6.30)
+.\" commit 7eafd7c74c3f2e67c27621b987b28397110d643f
+.\" https://lwn.net/Articles/312232/
+POSIX message queues (see
+.BR mq_overview (7)).
+The common characteristic of these IPC mechanisms is that IPC
+objects are identified by mechanisms other than filesystem
+pathnames.
+.P
+Each IPC namespace has its own set of System V IPC identifiers and
+its own POSIX message queue filesystem.
+Objects created in an IPC namespace are visible to all other processes
+that are members of that namespace,
+but are not visible to processes in other IPC namespaces.
+.P
+The following
+.I /proc
+interfaces are distinct in each IPC namespace:
+.IP \[bu] 3
+The POSIX message queue interfaces in
+.IR /proc/sys/fs/mqueue .
+.IP \[bu]
+The System V IPC interfaces in
+.IR /proc/sys/kernel ,
+namely:
+.IR msgmax ,
+.IR msgmnb  ,
+.IR msgmni ,
+.IR sem ,
+.IR shmall ,
+.IR shmmax ,
+.IR shmmni ,
+and
+.IR shm_rmid_forced .
+.IP \[bu]
+The System V IPC interfaces in
+.IR /proc/sysvipc .
+.P
+When an IPC namespace is destroyed
+(i.e., when the last process that is a member of the namespace terminates),
+all IPC objects in the namespace are automatically destroyed.
+.P
+Use of IPC namespaces requires a kernel that is configured with the
+.B CONFIG_IPC_NS
+option.
+.SH SEE ALSO
+.BR nsenter (1),
+.BR unshare (1),
+.BR clone (2),
+.BR setns (2),
+.BR unshare (2),
+.BR mq_overview (7),
+.BR namespaces (7),
+.BR sysvipc (7)
diff --git a/man/man7/ipv6.7 b/man/man7/ipv6.7
new file mode 100644
index 000000000..d9241cc93
--- /dev/null
+++ b/man/man7/ipv6.7
@@ -0,0 +1,416 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 2000 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: ipv6.7,v 1.3 2000/12/20 18:10:31 ak Exp $
+.\"
+.\" The following socket options are undocumented
+.\"	All of the following are from:
+.\"	    commit 333fad5364d6b457c8d837f7d05802d2aaf8a961
+.\"	    Author: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+.\"	    Support several new sockopt / ancillary data in Advanced API (RFC3542).
+.\"		IPV6_2292PKTINFO (2.6.14)
+.\"		    Formerly IPV6_PKTINFO
+.\"		IPV6_2292HOPOPTS (2.6.14)
+.\"		    Formerly IPV6_HOPOPTS, which is documented
+.\"		IPV6_2292DSTOPTS (2.6.14)
+.\"		    Formerly IPV6_DSTOPTS, which is documented
+.\"		IPV6_2292RTHDR (2.6.14)
+.\"		    Formerly IPV6_RTHDR, which is documented
+.\"		IPV6_2292PKTOPTIONS (2.6.14)
+.\"		    Formerly IPV6_PKTOPTIONS
+.\"		IPV6_2292HOPLIMIT (2.6.14)
+.\"		    Formerly IPV6_HOPLIMIT, which is documented
+.\"
+.\"		IPV6_RECVHOPLIMIT (2.6.14)
+.\"		IPV6_RECVHOPOPTS (2.6.14)
+.\"		IPV6_RTHDRDSTOPTS (2.6.14)
+.\"		IPV6_RECVRTHDR (2.6.14)
+.\"		IPV6_RECVDSTOPTS (2.6.14)
+.\"
+.\"	IPV6_RECVPATHMTU (Linux 2.6.35, flag value added in Linux 2.6.14)
+.\"	    commit 793b14731686595a741d9f47726ad8b9a235385a
+.\"	    Author: Brian Haley <brian.haley@hp.com>
+.\"	IPV6_PATHMTU (Linux 2.6.35, flag value added in Linux 2.6.14)
+.\"	    commit 793b14731686595a741d9f47726ad8b9a235385a
+.\"	    Author: Brian Haley <brian.haley@hp.com>
+.\"	IPV6_DONTFRAG (Linux 2.6.35, flag value added in Linux 2.6.14)
+.\"	    commit 793b14731686595a741d9f47726ad8b9a235385a
+.\"	    Author: Brian Haley <brian.haley@hp.com>
+.\"	    commit 4b340ae20d0e2366792abe70f46629e576adaf5e
+.\"	    Author: Brian Haley <brian.haley@hp.com>
+.\"
+.\"	IPV6_RECVTCLASS (Linux 2.6.14)
+.\"	    commit 41a1f8ea4fbfcdc4232f023732584aae2220de31
+.\"	    Author: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+.\"		Based on patch from David L Stevens <dlstevens@us.ibm.com>
+.\"
+.\"	IPV6_CHECKSUM (Linux 2.2)
+.\"	IPV6_NEXTHOP (Linux 2.2)
+.\"	IPV6_JOIN_ANYCAST (Linux 2.4.21 / Linux 2.6)
+.\"	IPV6_LEAVE_ANYCAST (Linux 2.4.21 / Linux 2.6)
+.\"	IPV6_FLOWLABEL_MGR (Linux 2.2.7 / Linux 2.4)
+.\"	IPV6_FLOWINFO_SEND (Linux 2.2.7 / Linux 2.4)
+.\"	IPV6_IPSEC_POLICY (Linux 2.6)
+.\"	IPV6_XFRM_POLICY (Linux 2.6)
+.\"	IPV6_TCLASS (Linux 2.6)
+.\"
+.\"	IPV6_ADDR_PREFERENCES (Linux 2.6.26)
+.\"	    commit 7cbca67c073263c179f605bdbbdc565ab29d801d
+.\"	    Author: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+.\"	IPV6_MINHOPCOUNT (Linux 2.6.35)
+.\"	    commit e802af9cabb011f09b9c19a82faef3dd315f27eb
+.\"	    Author: Stephen Hemminger <shemminger@vyatta.com>
+.\"	IPV6_ORIGDSTADDR (Linux 2.6.37)
+.\"	    Actually a CMSG rather than a sockopt?
+.\"	    In header file, we have IPV6_RECVORIGDSTADDR == IPV6_ORIGDSTADDR
+.\"	    commit 6c46862280c5f55eda7750391bc65cd7e08c7535
+.\"	    Author: Balazs Scheidler <bazsi@balabit.hu>
+.\"	IPV6_RECVORIGDSTADDR (Linux 2.6.37)
+.\"	    commit 6c46862280c5f55eda7750391bc65cd7e08c7535
+.\"	    Author: Balazs Scheidler <bazsi@balabit.hu>
+.\"	        Support for IPV6_RECVORIGDSTADDR sockopt for UDP sockets
+.\"		were contributed by Harry Mason.
+.\"	IPV6_TRANSPARENT (Linux 2.6.37)
+.\"	    commit 6c46862280c5f55eda7750391bc65cd7e08c7535
+.\"	    Author: Balazs Scheidler <bazsi@balabit.hu>
+.\"	IPV6_UNICAST_IF (Linux 3.4)
+.\"	    commit c4062dfc425e94290ac427a98d6b4721dd2bc91f
+.\"	    Author: Erich E. Hoover <ehoover@mines.edu>
+.\"
+.TH ipv6 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ipv6 \- Linux IPv6 protocol implementation
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <netinet/in.h>
+.P
+.IB tcp6_socket " = socket(AF_INET6, SOCK_STREAM, 0);"
+.IB raw6_socket " = socket(AF_INET6, SOCK_RAW, " protocol ");"
+.IB udp6_socket " = socket(AF_INET6, SOCK_DGRAM, " protocol ");"
+.fi
+.SH DESCRIPTION
+Linux 2.2 optionally implements the Internet Protocol, version 6.
+This man page contains a description of the IPv6 basic API as
+implemented by the Linux kernel and glibc 2.1.
+The interface
+is based on the BSD sockets interface; see
+.BR socket (7).
+.P
+The IPv6 API aims to be mostly compatible with the
+IPv4 API (see
+.BR ip (7)).
+Only differences are described in this man page.
+.P
+To bind an
+.B AF_INET6
+socket to any process, the local address should be copied from the
+.I in6addr_any
+variable which has
+.I in6_addr
+type.
+In static initializations,
+.B IN6ADDR_ANY_INIT
+may also be used, which expands to a constant expression.
+Both of them are in network byte order.
+.P
+The IPv6 loopback address (::1) is available in the global
+.I in6addr_loopback
+variable.
+For initializations,
+.B IN6ADDR_LOOPBACK_INIT
+should be used.
+.P
+IPv4 connections can be handled with the v6 API by using the
+v4-mapped-on-v6 address type;
+thus a program needs to support only this API type to
+support both protocols.
+This is handled transparently by the address
+handling functions in the C library.
+.P
+IPv4 and IPv6 share the local port space.
+When you get an IPv4 connection
+or packet to an IPv6 socket,
+its source address will be mapped to v6.
+.SS Address format
+.in +4n
+.EX
+struct sockaddr_in6 {
+    sa_family_t     sin6_family;   /* AF_INET6 */
+    in_port_t       sin6_port;     /* port number */
+    uint32_t        sin6_flowinfo; /* IPv6 flow information */
+    struct in6_addr sin6_addr;     /* IPv6 address */
+    uint32_t        sin6_scope_id; /* Scope ID (new in Linux 2.4) */
+};
+\&
+struct in6_addr {
+    unsigned char   s6_addr[16];   /* IPv6 address */
+};
+.EE
+.in
+.P
+.I sin6_family
+is always set to
+.BR AF_INET6 ;
+.I sin6_port
+is the protocol port (see
+.I sin_port
+in
+.BR ip (7));
+.I sin6_flowinfo
+is the IPv6 flow identifier;
+.I sin6_addr
+is the 128-bit IPv6 address.
+.I sin6_scope_id
+is an ID depending on the scope of the address.
+It is new in Linux 2.4.
+Linux supports it only for link-local addresses, in that case
+.I sin6_scope_id
+contains the interface index (see
+.BR netdevice (7))
+.P
+IPv6 supports several address types: unicast to address a single
+host, multicast to address a group of hosts,
+anycast to address the nearest member of a group of hosts
+(not implemented in Linux), IPv4-on-IPv6 to
+address an IPv4 host, and other reserved address types.
+.P
+The address notation for IPv6 is a group of 8 4-digit hexadecimal
+numbers, separated with a \[aq]:\[aq].
+\&"::" stands for a string of 0 bits.
+Special addresses are ::1 for loopback and ::FFFF:<IPv4 address>
+for IPv4-mapped-on-IPv6.
+.P
+The port space of IPv6 is shared with IPv4.
+.SS Socket options
+IPv6 supports some protocol-specific socket options that can be set with
+.BR setsockopt (2)
+and read with
+.BR getsockopt (2).
+The socket option level for IPv6 is
+.BR IPPROTO_IPV6 .
+A boolean integer flag is zero when it is false, otherwise true.
+.TP
+.B IPV6_ADDRFORM
+Turn an
+.B AF_INET6
+socket into a socket of a different address family.
+Only
+.B AF_INET
+is currently supported for that.
+It is allowed only for IPv6 sockets
+that are connected and bound to a v4-mapped-on-v6 address.
+The argument is a pointer to an integer containing
+.BR AF_INET .
+This is useful to pass v4-mapped sockets as file descriptors to
+programs that don't know how to deal with the IPv6 API.
+.TP
+.B IPV6_ADD_MEMBERSHIP, IPV6_DROP_MEMBERSHIP
+Control membership in multicast groups.
+Argument is a pointer to a
+.IR "struct ipv6_mreq" .
+.TP
+.B IPV6_MTU
+.BR getsockopt ():
+Retrieve the current known path MTU of the current socket.
+Valid only when the socket has been connected.
+Returns an integer.
+.IP
+.BR setsockopt ():
+Set the MTU to be used for the socket.
+The MTU is limited by the device
+MTU or the path MTU when path MTU discovery is enabled.
+Argument is a pointer to integer.
+.TP
+.B IPV6_MTU_DISCOVER
+Control path-MTU discovery on the socket.
+See
+.B IP_MTU_DISCOVER
+in
+.BR ip (7)
+for details.
+.TP
+.B IPV6_MULTICAST_HOPS
+Set the multicast hop limit for the socket.
+Argument is a pointer to an
+integer.
+\-1 in the value means use the route default, otherwise it should be
+between 0 and 255.
+.TP
+.B IPV6_MULTICAST_IF
+Set the device for outgoing multicast packets on the socket.
+This is allowed only for
+.B SOCK_DGRAM
+and
+.B SOCK_RAW
+socket.
+The argument is a pointer to an interface index (see
+.BR netdevice (7))
+in an integer.
+.TP
+.B IPV6_MULTICAST_LOOP
+Control whether the socket sees multicast packets that it has send itself.
+Argument is a pointer to boolean.
+.TP
+.BR IPV6_RECVPKTINFO " (since Linux 2.6.14)"
+Set delivery of the
+.B IPV6_PKTINFO
+control message on incoming datagrams.
+Such control messages contain a
+.IR "struct in6_pktinfo" ,
+as per RFC 3542.
+Allowed only for
+.B SOCK_DGRAM
+or
+.B SOCK_RAW
+sockets.
+Argument is a pointer to a boolean value in an integer.
+.TP
+.B \%IPV6_RTHDR, \%IPV6_AUTHHDR, \%IPV6_DSTOPTS, \%IPV6_HOPOPTS, \
+\%IPV6_FLOWINFO, \%IPV6_HOPLIMIT
+Set delivery of control messages for incoming datagrams containing
+extension headers from the received packet.
+.B IPV6_RTHDR
+delivers the routing header,
+.B IPV6_AUTHHDR
+delivers the authentication header,
+.B IPV6_DSTOPTS
+delivers the destination options,
+.B IPV6_HOPOPTS
+delivers the hop options,
+.B IPV6_FLOWINFO
+delivers an integer containing the flow ID,
+.B IPV6_HOPLIMIT
+delivers an integer containing the hop count of the packet.
+The control messages have the same type as the socket option.
+All these header options can also be set for outgoing packets
+by putting the appropriate control message into the control buffer of
+.BR sendmsg (2).
+Allowed only for
+.B SOCK_DGRAM
+or
+.B SOCK_RAW
+sockets.
+Argument is a pointer to a boolean value.
+.TP
+.B IPV6_RECVERR
+Control receiving of asynchronous error options.
+See
+.B IP_RECVERR
+in
+.BR ip (7)
+for details.
+Argument is a pointer to boolean.
+.TP
+.B IPV6_ROUTER_ALERT
+Pass forwarded packets containing a router alert hop-by-hop option to
+this socket.
+Allowed only for
+.B SOCK_RAW
+sockets.
+The tapped packets are not forwarded by the kernel, it is the
+user's responsibility to send them out again.
+Argument is a pointer to an integer.
+A positive integer indicates a router alert option value to intercept.
+Packets carrying a router alert option with a value field containing
+this integer will be delivered to the socket.
+A negative integer disables delivery of packets with router alert options
+to this socket.
+.TP
+.B IPV6_UNICAST_HOPS
+Set the unicast hop limit for the socket.
+Argument is a pointer to an integer.
+\-1 in the value means use the route default,
+otherwise it should be between 0 and 255.
+.TP
+.BR IPV6_V6ONLY " (since Linux 2.4.21 and 2.6)"
+.\" See RFC 3493
+If this flag is set to true (nonzero), then the socket is restricted
+to sending and receiving IPv6 packets only.
+In this case, an IPv4 and an IPv6 application can bind
+to a single port at the same time.
+.IP
+If this flag is set to false (zero),
+then the socket can be used to send and receive packets
+to and from an IPv6 address or an IPv4-mapped IPv6 address.
+.IP
+The argument is a pointer to a boolean value in an integer.
+.IP
+The default value for this flag is defined by the contents of the file
+.IR /proc/sys/net/ipv6/bindv6only .
+The default value for that file is 0 (false).
+.\" FLOWLABEL_MGR, FLOWINFO_SEND
+.SH ERRORS
+.TP
+.B ENODEV
+The user tried to
+.BR bind (2)
+to a link-local IPv6 address, but the
+.I sin6_scope_id
+in the supplied
+.I sockaddr_in6
+structure is not a valid
+interface index.
+.SH VERSIONS
+Linux 2.4 will break binary compatibility for the
+.I sockaddr_in6
+for 64-bit
+hosts by changing the alignment of
+.I in6_addr
+and adding an additional
+.I sin6_scope_id
+field.
+The kernel interfaces stay compatible, but a program including
+.I sockaddr_in6
+or
+.I in6_addr
+into other structures may not be.
+This is not
+a problem for 32-bit hosts like i386.
+.P
+The
+.I sin6_flowinfo
+field is new in Linux 2.4.
+It is transparently passed/read by the kernel
+when the passed address length contains it.
+Some programs that pass a longer address buffer and then
+check the outgoing address length may break.
+.SH NOTES
+The
+.I sockaddr_in6
+structure is bigger than the generic
+.IR sockaddr .
+Programs that assume that all address types can be stored safely in a
+.I struct sockaddr
+need to be changed to use
+.I struct sockaddr_storage
+for that instead.
+.P
+.BR SOL_IP ,
+.BR SOL_IPV6 ,
+.BR SOL_ICMPV6 ,
+and other
+.B SOL_*
+socket options are nonportable variants of
+.BR IPPROTO_* .
+See also
+.BR ip (7).
+.SH BUGS
+The IPv6 extended API as in RFC\ 2292 is currently only partly
+implemented;
+although the 2.2 kernel has near complete support for receiving options,
+the macros for generating IPv6 options are missing in glibc 2.1.
+.P
+IPSec support for EH and AH headers is missing.
+.P
+Flow label management is not complete and not documented here.
+.P
+This man page is not complete.
+.SH SEE ALSO
+.BR cmsg (3),
+.BR ip (7)
+.P
+RFC\ 2553: IPv6 BASIC API;
+Linux tries to be compliant to this.
+RFC\ 2460: IPv6 specification.
diff --git a/man/man7/iso-8859-1.7 b/man/man7/iso-8859-1.7
new file mode 100644
index 000000000..1969dfb2f
--- /dev/null
+++ b/man/man7/iso-8859-1.7
@@ -0,0 +1 @@
+.so man7/iso_8859-1.7
diff --git a/man/man7/iso-8859-10.7 b/man/man7/iso-8859-10.7
new file mode 100644
index 000000000..9b4658f25
--- /dev/null
+++ b/man/man7/iso-8859-10.7
@@ -0,0 +1 @@
+.so man7/iso_8859-10.7
diff --git a/man/man7/iso-8859-11.7 b/man/man7/iso-8859-11.7
new file mode 100644
index 000000000..cbd4cfe7c
--- /dev/null
+++ b/man/man7/iso-8859-11.7
@@ -0,0 +1 @@
+.so man7/iso_8859-11.7
diff --git a/man/man7/iso-8859-13.7 b/man/man7/iso-8859-13.7
new file mode 100644
index 000000000..8ad23352e
--- /dev/null
+++ b/man/man7/iso-8859-13.7
@@ -0,0 +1 @@
+.so man7/iso_8859-13.7
diff --git a/man/man7/iso-8859-14.7 b/man/man7/iso-8859-14.7
new file mode 100644
index 000000000..4aa555db9
--- /dev/null
+++ b/man/man7/iso-8859-14.7
@@ -0,0 +1 @@
+.so man7/iso_8859-14.7
diff --git a/man/man7/iso-8859-15.7 b/man/man7/iso-8859-15.7
new file mode 100644
index 000000000..a4095d754
--- /dev/null
+++ b/man/man7/iso-8859-15.7
@@ -0,0 +1 @@
+.so man7/iso_8859-15.7
diff --git a/man/man7/iso-8859-16.7 b/man/man7/iso-8859-16.7
new file mode 100644
index 000000000..b9c8e9182
--- /dev/null
+++ b/man/man7/iso-8859-16.7
@@ -0,0 +1 @@
+.so man7/iso_8859-16.7
diff --git a/man/man7/iso-8859-2.7 b/man/man7/iso-8859-2.7
new file mode 100644
index 000000000..da36668dd
--- /dev/null
+++ b/man/man7/iso-8859-2.7
@@ -0,0 +1 @@
+.so man7/iso_8859-2.7
diff --git a/man/man7/iso-8859-3.7 b/man/man7/iso-8859-3.7
new file mode 100644
index 000000000..75e42ce3d
--- /dev/null
+++ b/man/man7/iso-8859-3.7
@@ -0,0 +1 @@
+.so man7/iso_8859-3.7
diff --git a/man/man7/iso-8859-4.7 b/man/man7/iso-8859-4.7
new file mode 100644
index 000000000..15a829eb3
--- /dev/null
+++ b/man/man7/iso-8859-4.7
@@ -0,0 +1 @@
+.so man7/iso_8859-4.7
diff --git a/man/man7/iso-8859-5.7 b/man/man7/iso-8859-5.7
new file mode 100644
index 000000000..1f20320e7
--- /dev/null
+++ b/man/man7/iso-8859-5.7
@@ -0,0 +1 @@
+.so man7/iso_8859-5.7
diff --git a/man/man7/iso-8859-6.7 b/man/man7/iso-8859-6.7
new file mode 100644
index 000000000..edcafdf6e
--- /dev/null
+++ b/man/man7/iso-8859-6.7
@@ -0,0 +1 @@
+.so man7/iso_8859-6.7
diff --git a/man/man7/iso-8859-7.7 b/man/man7/iso-8859-7.7
new file mode 100644
index 000000000..951384c99
--- /dev/null
+++ b/man/man7/iso-8859-7.7
@@ -0,0 +1 @@
+.so man7/iso_8859-7.7
diff --git a/man/man7/iso-8859-8.7 b/man/man7/iso-8859-8.7
new file mode 100644
index 000000000..07cf21627
--- /dev/null
+++ b/man/man7/iso-8859-8.7
@@ -0,0 +1 @@
+.so man7/iso_8859-8.7
diff --git a/man/man7/iso-8859-9.7 b/man/man7/iso-8859-9.7
new file mode 100644
index 000000000..0fcc7d463
--- /dev/null
+++ b/man/man7/iso-8859-9.7
@@ -0,0 +1 @@
+.so man7/iso_8859-9.7
diff --git a/man/man7/iso_8859-1.7 b/man/man7/iso_8859-1.7
new file mode 100644
index 000000000..f07cb330a
--- /dev/null
+++ b/man/man7/iso_8859-1.7
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright 1993-1995 Daniel Quinlan (quinlan@yggdrasil.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Slightly rearranged, aeb, 950713
+.\" Updated, dpo, 990531
+.TH ISO_8859-1 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-1 \- ISO/IEC\~8859-1 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-1 encodes the
+characters used in many West European languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-1 characters
+The following table displays the characters in ISO/IEC\~8859-1 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	¡	INVERTED EXCLAMATION MARK
+242	162	A2	¢	CENT SIGN
+243	163	A3	£	POUND SIGN
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	¥	YEN SIGN
+246	166	A6	¦	BROKEN BAR
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	ª	FEMININE ORDINAL INDICATOR
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	¯	MACRON
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	´	ACUTE ACCENT
+265	181	B5	µ	MICRO SIGN
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	¸	CEDILLA
+271	185	B9	¹	SUPERSCRIPT ONE
+272	186	BA	º	MASCULINE ORDINAL INDICATOR
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	¼	VULGAR FRACTION ONE QUARTER
+275	189	BD	½	VULGAR FRACTION ONE HALF
+276	190	BE	¾	VULGAR FRACTION THREE QUARTERS
+277	191	BF	¿	INVERTED QUESTION MARK
+300	192	C0	À	LATIN CAPITAL LETTER A WITH GRAVE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ã	LATIN CAPITAL LETTER A WITH TILDE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	È	LATIN CAPITAL LETTER E WITH GRAVE
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ê	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ì	LATIN CAPITAL LETTER I WITH GRAVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+320	208	D0	Ð	LATIN CAPITAL LETTER ETH
+321	209	D1	Ñ	LATIN CAPITAL LETTER N WITH TILDE
+322	210	D2	Ò	LATIN CAPITAL LETTER O WITH GRAVE
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+331	217	D9	Ù	LATIN CAPITAL LETTER U WITH GRAVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ý	LATIN CAPITAL LETTER Y WITH ACUTE
+336	222	DE	Þ	LATIN CAPITAL LETTER THORN
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	à	LATIN SMALL LETTER A WITH GRAVE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ã	LATIN SMALL LETTER A WITH TILDE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	è	LATIN SMALL LETTER E WITH GRAVE
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ê	LATIN SMALL LETTER E WITH CIRCUMFLEX
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ì	LATIN SMALL LETTER I WITH GRAVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+360	240	F0	ð	LATIN SMALL LETTER ETH
+361	241	F1	ñ	LATIN SMALL LETTER N WITH TILDE
+362	242	F2	ò	LATIN SMALL LETTER O WITH GRAVE
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ø	LATIN SMALL LETTER O WITH STROKE
+371	249	F9	ù	LATIN SMALL LETTER U WITH GRAVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ý	LATIN SMALL LETTER Y WITH ACUTE
+376	254	FE	þ	LATIN SMALL LETTER THORN
+377	255	FF	ÿ	LATIN SMALL LETTER Y WITH DIAERESIS
+.TE
+.SH NOTES
+ISO/IEC\~8859-1 is also known as Latin-1.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR cp1252 (7),
+.BR iso_8859\-15 (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-10.7 b/man/man7/iso_8859-10.7
new file mode 100644
index 000000000..61ddd19ca
--- /dev/null
+++ b/man/man7/iso_8859-10.7
@@ -0,0 +1,146 @@
+'\" t
+.\" Copyright 2009    Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-10 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-10 \- ISO/IEC\~8859-10 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-10 encodes the
+characters used in Nordic languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-10 characters
+The following table displays the characters in ISO/IEC\~8859-10 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ą	LATIN CAPITAL LETTER A WITH OGONEK
+242	162	A2	Ē	LATIN CAPITAL LETTER E WITH MACRON
+243	163	A3	Ģ	LATIN CAPITAL LETTER G WITH CEDILLA
+244	164	A4	Ī	LATIN CAPITAL LETTER I WITH MACRON
+245	165	A5	Ĩ	LATIN CAPITAL LETTER I WITH TILDE
+246	166	A6	Ķ	LATIN CAPITAL LETTER K WITH CEDILLA
+247	167	A7	§	SECTION SIGN
+250	168	A8	Ļ	LATIN CAPITAL LETTER L WITH CEDILLA
+251	169	A9	Đ	LATIN CAPITAL LETTER D WITH STROKE
+252	170	AA	Š	LATIN CAPITAL LETTER S WITH CARON
+253	171	AB	Ŧ	LATIN CAPITAL LETTER T WITH STROKE
+254	172	AC	Ž	LATIN CAPITAL LETTER Z WITH CARON
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	Ū	LATIN CAPITAL LETTER U WITH MACRON
+257	175	AF	Ŋ	LATIN CAPITAL LETTER ENG
+260	176	B0	°	DEGREE SIGN
+261	177	B1	ą	LATIN SMALL LETTER A WITH OGONEK
+262	178	B2	ē	LATIN SMALL LETTER E WITH MACRON
+263	179	B3	ģ	LATIN SMALL LETTER G WITH CEDILLA
+264	180	B4	ī	LATIN SMALL LETTER I WITH MACRON
+265	181	B5	ĩ	LATIN SMALL LETTER I WITH TILDE
+266	182	B6	ķ	LATIN SMALL LETTER K WITH CEDILLA
+267	183	B7	·	MIDDLE DOT
+270	184	B8	ļ	LATIN SMALL LETTER L WITH CEDILLA
+271	185	B9	đ	LATIN SMALL LETTER D WITH STROKE
+272	186	BA	š	LATIN SMALL LETTER S WITH CARON
+273	187	BB	ŧ	LATIN SMALL LETTER T WITH STROKE
+274	188	BC	ž	LATIN SMALL LETTER Z WITH CARON
+275	189	BD	―	HORIZONTAL BAR
+276	190	BE	ū	LATIN SMALL LETTER U WITH MACRON
+277	191	BF	ŋ	LATIN SMALL LETTER ENG
+300	192	C0	Ā	LATIN CAPITAL LETTER A WITH MACRON
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ã	LATIN CAPITAL LETTER A WITH TILDE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Į	LATIN CAPITAL LETTER I WITH OGONEK
+310	200	C8	Č	LATIN CAPITAL LETTER C WITH CARON
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ę	LATIN CAPITAL LETTER E WITH OGONEK
+312	202	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ė	LATIN CAPITAL LETTER E WITH DOT ABOVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+320	208	D0	Ð	LATIN CAPITAL LETTER ETH
+321	209	D1	Ņ	LATIN CAPITAL LETTER N WITH CEDILLA
+322	210	D2	Ō	LATIN CAPITAL LETTER O WITH MACRON
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	Ũ	LATIN CAPITAL LETTER U WITH TILDE
+330	216	D8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+331	217	D9	Ų	LATIN CAPITAL LETTER U WITH OGONEK
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ý	LATIN CAPITAL LETTER Y WITH ACUTE
+336	222	DE	Þ	LATIN CAPITAL LETTER THORN
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	ā	LATIN SMALL LETTER A WITH MACRON
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ã	LATIN SMALL LETTER A WITH TILDE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	į	LATIN SMALL LETTER I WITH OGONEK
+350	232	E8	č	LATIN SMALL LETTER C WITH CARON
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ę	LATIN SMALL LETTER E WITH OGONEK
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ė	LATIN SMALL LETTER E WITH DOT ABOVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+360	240	F0	ð	LATIN SMALL LETTER ETH
+361	241	F1	ņ	LATIN SMALL LETTER N WITH CEDILLA
+362	242	F2	ō	LATIN SMALL LETTER O WITH MACRON
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	ũ	LATIN SMALL LETTER U WITH TILDE
+370	248	F8	ø	LATIN SMALL LETTER O WITH STROKE
+371	249	F9	ų	LATIN SMALL LETTER U WITH OGONEK
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ý	LATIN SMALL LETTER Y WITH ACUTE
+376	254	FE	þ	LATIN SMALL LETTER THORN
+377	255	FF	ĸ	LATIN SMALL LETTER KRA
+.TE
+.SH NOTES
+ISO/IEC\~8859-10 is also known as Latin-6.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-11.7 b/man/man7/iso_8859-11.7
new file mode 100644
index 000000000..89933f64a
--- /dev/null
+++ b/man/man7/iso_8859-11.7
@@ -0,0 +1,143 @@
+'\" t
+.\" Copyright 2009 Lefteris Dimitroulakis <edimitro at tee.gr>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\"Thanomsub Noppaburana <donga.nb@gmail.com> made valuable suggestions.
+.\"
+.TH ISO_8859-11 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-11 \- ISO/IEC\~8859-11 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-11 encodes the
+characters used in the Thai language.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-11 characters
+The following table displays the characters in ISO/IEC\~8859-11 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	ก	THAI CHARACTER KO KAI
+242	162	A2	ข	THAI CHARACTER KHO KHAI
+243	163	A3	ฃ	THAI CHARACTER KHO KHUAT
+244	164	A4	ค	THAI CHARACTER KHO KHWAI
+245	165	A5	ฅ	THAI CHARACTER KHO KHON
+246	166	A6	ฆ	THAI CHARACTER KHO RAKHANG
+247	167	A7	ง	THAI CHARACTER NGO NGU
+250	168	A8	จ	THAI CHARACTER CHO CHAN
+251	169	A9	ฉ	THAI CHARACTER CHO CHING
+252	170	AA	ช	THAI CHARACTER CHO CHANG
+253	171	AB	ซ	THAI CHARACTER SO SO
+254	172	AC	ฌ	THAI CHARACTER CHO CHOE
+255	173	AD	ญ	THAI CHARACTER YO YING
+256	174	AE	ฎ	THAI CHARACTER DO CHADA
+257	175	AF	ฏ	THAI CHARACTER TO PATAK
+260	176	B0	ฐ	THAI CHARACTER THO THAN
+261	177	B1	ฑ	THAI CHARACTER THO NANGMONTHO
+262	178	B2	ฒ	THAI CHARACTER THO PHUTHAO
+263	179	B3	ณ	THAI CHARACTER NO NEN
+264	180	B4	ด	THAI CHARACTER DO DEK
+265	181	B5	ต	THAI CHARACTER TO TAO
+266	182	B6	ถ	THAI CHARACTER THO THUNG
+267	183	B7	ท	THAI CHARACTER THO THAHAN
+270	184	B8	ธ	THAI CHARACTER THO THONG
+271	185	B9	น	THAI CHARACTER NO NU
+272	186	BA	บ	THAI CHARACTER BO BAIMAI
+273	187	BB	ป	THAI CHARACTER PO PLA
+274	188	BC	ผ	THAI CHARACTER PHO PHUNG
+275	189	BD	ฝ	THAI CHARACTER FO FA
+276	190	BE	พ	THAI CHARACTER PHO PHAN
+277	191	BF	ฟ	THAI CHARACTER FO FAN
+300	192	C0	ภ	THAI CHARACTER PHO SAMPHAO
+301	193	C1	ม	THAI CHARACTER MO MA
+302	194	C2	ย	THAI CHARACTER YO YAK
+303	195	C3	ร	THAI CHARACTER RO RUA
+304	196	C4	ฤ	THAI CHARACTER RU
+305	197	C5	ล	THAI CHARACTER LO LING
+306	198	C6	ฦ	THAI CHARACTER LU
+307	199	C7	ว	THAI CHARACTER WO WAEN
+310	200	C8	ศ	THAI CHARACTER SO SALA
+311	201	C9	ษ	THAI CHARACTER SO RUSI
+312	202	CA	ส	THAI CHARACTER SO SUA
+313	203	CB	ห	THAI CHARACTER HO HIP
+314	204	CC	ฬ	THAI CHARACTER LO CHULA
+315	205	CD	อ	THAI CHARACTER O ANG
+316	206	CE	ฮ	THAI CHARACTER HO NOKHUK
+317	207	CF	ฯ	THAI CHARACTER PAIYANNOI
+320	208	D0	ะ	THAI CHARACTER SARA A
+321	209	D1	ั 	THAI CHARACTER MAI HAN-AKAT
+322	210	D2	า	THAI CHARACTER SARA AA
+323	211	D3	ำ	THAI CHARACTER SARA AM
+324	212	D4	ิ 	THAI CHARACTER SARA I
+325	213	D5	ี 	THAI CHARACTER SARA II
+326	214	D6	ึ 	THAI CHARACTER SARA UE
+327	215	D7	ื 	THAI CHARACTER SARA UEE
+330	216	D8	ุ 	THAI CHARACTER SARA U
+331	217	D9	ู 	THAI CHARACTER SARA UU
+332	218	DA	ฺ 	THAI CHARACTER PHINTHU
+337	223	DF	฿	THAI CURRENCY SYMBOL BAHT
+340	224	E0	เ	THAI CHARACTER SARA E
+341	225	E1	แ	THAI CHARACTER SARA AE
+342	226	E2	โ	THAI CHARACTER SARA O
+343	227	E3	ใ	THAI CHARACTER SARA AI MAIMUAN
+344	228	E4	ไ	THAI CHARACTER SARA AI MAIMALAI
+345	229	E5	ๅ	THAI CHARACTER LAKKHANGYAO
+346	230	E6	ๆ	THAI CHARACTER MAIYAMOK
+347	231	E7	็ 	THAI CHARACTER MAITAIKHU
+350	232	E8	่ 	THAI CHARACTER MAI EK
+351	233	E9	้ 	THAI CHARACTER MAI THO
+352	234	EA	๊ 	THAI CHARACTER MAI TRI
+353	235	EB	๋ 	THAI CHARACTER MAI CHATTAWA
+354	236	EC	์ 	THAI CHARACTER THANTHAKHAT
+355	237	ED	ํ 	THAI CHARACTER NIKHAHIT
+356	238	EE	๎ 	THAI CHARACTER YAMAKKAN
+357	239	EF	๏	THAI CHARACTER FONGMAN
+360	240	F0	๐	THAI DIGIT ZERO
+361	241	F1	๑	THAI DIGIT ONE
+362	242	F2	๒	THAI DIGIT TWO
+363	243	F3	๓	THAI DIGIT THREE
+364	244	F4	๔	THAI DIGIT FOUR
+365	245	F5	๕	THAI DIGIT FIVE
+366	246	F6	๖	THAI DIGIT SIX
+367	247	F7	๗	THAI DIGIT SEVEN
+370	248	F8	๘	THAI DIGIT EIGHT
+371	249	F9	๙	THAI DIGIT NINE
+372	250	FA	๚	THAI CHARACTER ANGKHANKHU
+373	251	FB	๛	THAI CHARACTER KHOMUT
+.TE
+.SH NOTES
+ISO/IEC\~8859-11 is the same as TIS (Thai Industrial Standard) 620-2253,
+commonly known as TIS-620, except for the character in position A0:
+ISO/IEC\~8859-11 defines this as NO-BREAK SPACE,
+while TIS-620 leaves it undefined.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-13.7 b/man/man7/iso_8859-13.7
new file mode 100644
index 000000000..98fac15a9
--- /dev/null
+++ b/man/man7/iso_8859-13.7
@@ -0,0 +1,146 @@
+'\" t
+.\" Copyright 2009   Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-13 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-13 \- ISO/IEC\~8859-13 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-13 encodes the
+characters used in Baltic Rim languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-13 characters
+The following table displays the characters in ISO/IEC\~8859-13 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	”	RIGHT DOUBLE QUOTATION MARK
+242	162	A2	¢	CENT SIGN
+243	163	A3	£	POUND SIGN
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	„	DOUBLE LOW-9 QUOTATION MARK
+246	166	A6	¦	BROKEN BAR
+247	167	A7	§	SECTION SIGN
+250	168	A8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	Ŗ	LATIN CAPITAL LETTER R WITH CEDILLA
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	Æ	LATIN CAPITAL LETTER AE
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	“	LEFT DOUBLE QUOTATION MARK
+265	181	B5	µ	MICRO SIGN
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	ø	LATIN SMALL LETTER O WITH STROKE
+271	185	B9	¹	SUPERSCRIPT ONE
+272	186	BA	ŗ	LATIN SMALL LETTER R WITH CEDILLA
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	¼	VULGAR FRACTION ONE QUARTER
+275	189	BD	½	VULGAR FRACTION ONE HALF
+276	190	BE	¾	VULGAR FRACTION THREE QUARTERS
+277	191	BF	æ	LATIN SMALL LETTER AE
+300	192	C0	Ą	LATIN CAPITAL LETTER A WITH OGONEK
+301	193	C1	Į	LATIN CAPITAL LETTER I WITH OGONEK
+302	194	C2	Ā	LATIN CAPITAL LETTER A WITH MACRON
+303	195	C3	Ć	LATIN CAPITAL LETTER C WITH ACUTE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Ę	LATIN CAPITAL LETTER E WITH OGONEK
+307	199	C7	Ē	LATIN CAPITAL LETTER E WITH MACRON
+310	200	C8	Č	LATIN CAPITAL LETTER C WITH CARON
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ź	LATIN CAPITAL LETTER Z WITH ACUTE
+313	203	CB	Ė	LATIN CAPITAL LETTER E WITH DOT ABOVE
+314	204	CC	Ģ	LATIN CAPITAL LETTER G WITH CEDILLA
+315	205	CD	Ķ	LATIN CAPITAL LETTER K WITH CEDILLA
+316	206	CE	Ī	LATIN CAPITAL LETTER I WITH MACRON
+317	207	CF	Ļ	LATIN CAPITAL LETTER L WITH CEDILLA
+320	208	D0	Š	LATIN CAPITAL LETTER S WITH CARON
+321	209	D1	Ń	LATIN CAPITAL LETTER N WITH ACUTE
+322	210	D2	Ņ	LATIN CAPITAL LETTER N WITH CEDILLA
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ō	LATIN CAPITAL LETTER O WITH MACRON
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ų	LATIN CAPITAL LETTER U WITH OGONEK
+331	217	D9	Ł	LATIN CAPITAL LETTER L WITH STROKE
+332	218	DA	Ś	LATIN CAPITAL LETTER S WITH ACUTE
+333	219	DB	Ū	LATIN CAPITAL LETTER U WITH MACRON
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ż	LATIN CAPITAL LETTER Z WITH DOT ABOVE
+336	222	DE	Ž	LATIN CAPITAL LETTER Z WITH CARON
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	ą	LATIN SMALL LETTER A WITH OGONEK
+341	225	E1	į	LATIN SMALL LETTER I WITH OGONEK
+342	226	E2	ā	LATIN SMALL LETTER A WITH MACRON
+343	227	E3	ć	LATIN SMALL LETTER C WITH ACUTE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	ę	LATIN SMALL LETTER E WITH OGONEK
+347	231	E7	ē	LATIN SMALL LETTER E WITH MACRON
+350	232	E8	č	LATIN SMALL LETTER C WITH CARON
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ź	LATIN SMALL LETTER Z WITH ACUTE
+353	235	EB	ė	LATIN SMALL LETTER E WITH DOT ABOVE
+354	236	EC	ģ	LATIN SMALL LETTER G WITH CEDILLA
+355	237	ED	ķ	LATIN SMALL LETTER K WITH CEDILLA
+356	238	EE	ī	LATIN SMALL LETTER I WITH MACRON
+357	239	EF	ļ	LATIN SMALL LETTER L WITH CEDILLA
+360	240	F0	š	LATIN SMALL LETTER S WITH CARON
+361	241	F1	ń	LATIN SMALL LETTER N WITH ACUTE
+362	242	F2	ņ	LATIN SMALL LETTER N WITH CEDILLA
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ō	LATIN SMALL LETTER O WITH MACRON
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ų	LATIN SMALL LETTER U WITH OGONEK
+371	249	F9	ł	LATIN SMALL LETTER L WITH STROKE
+372	250	FA	ś	LATIN SMALL LETTER S WITH ACUTE
+373	251	FB	ū	LATIN SMALL LETTER U WITH MACRON
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ż	LATIN SMALL LETTER Z WITH DOT ABOVE
+376	254	FE	ž	LATIN SMALL LETTER Z WITH CARON
+377	255	FF	’	RIGHT SINGLE QUOTATION MARK
+.TE
+.SH NOTES
+ISO/IEC\~8859-13 is also known as Latin-7.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-14.7 b/man/man7/iso_8859-14.7
new file mode 100644
index 000000000..f729f05ea
--- /dev/null
+++ b/man/man7/iso_8859-14.7
@@ -0,0 +1,146 @@
+'\" t
+.\" Copyright 2009   Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-14 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-14 \- ISO/IEC\~8859-14 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-14 encodes the
+characters used in Celtic languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-14 characters
+The following table displays the characters in ISO/IEC\~8859-14 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ḃ	LATIN CAPITAL LETTER B WITH DOT ABOVE
+242	162	A2	ḃ	LATIN SMALL LETTER B WITH DOT ABOVE
+243	163	A3	£	POUND SIGN
+244	164	A4	Ċ	LATIN CAPITAL LETTER C WITH DOT ABOVE
+245	165	A5	ċ	LATIN SMALL LETTER C WITH DOT ABOVE
+246	166	A6	Ḋ	LATIN CAPITAL LETTER D WITH DOT ABOVE
+247	167	A7	§	SECTION SIGN
+250	168	A8	Ẁ	LATIN CAPITAL LETTER W WITH GRAVE
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	Ẃ	LATIN CAPITAL LETTER W WITH ACUTE
+253	171	AB	ḋ	LATIN SMALL LETTER D WITH DOT ABOVE
+254	172	AC	Ỳ	LATIN CAPITAL LETTER Y WITH GRAVE
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	Ÿ	LATIN CAPITAL LETTER Y WITH DIAERESIS
+260	176	B0	Ḟ	LATIN CAPITAL LETTER F WITH DOT ABOVE
+261	177	B1	ḟ	LATIN SMALL LETTER F WITH DOT ABOVE
+262	178	B2	Ġ	LATIN CAPITAL LETTER G WITH DOT ABOVE
+263	179	B3	ġ	LATIN SMALL LETTER G WITH DOT ABOVE
+264	180	B4	Ṁ	LATIN CAPITAL LETTER M WITH DOT ABOVE
+265	181	B5	ṁ	LATIN SMALL LETTER M WITH DOT ABOVE
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	Ṗ	LATIN CAPITAL LETTER P WITH DOT ABOVE
+270	184	B8	ẁ	LATIN SMALL LETTER W WITH GRAVE
+271	185	B9	ṗ	LATIN SMALL LETTER P WITH DOT ABOVE
+272	186	BA	ẃ	LATIN SMALL LETTER W WITH ACUTE
+273	187	BB	Ṡ	LATIN CAPITAL LETTER S WITH DOT ABOVE
+274	188	BC	ỳ	LATIN SMALL LETTER Y WITH GRAVE
+275	189	BD	Ẅ	LATIN CAPITAL LETTER W WITH DIAERESIS
+276	190	BE	ẅ	LATIN SMALL LETTER W WITH DIAERESIS
+277	191	BF	ṡ	LATIN SMALL LETTER S WITH DOT ABOVE
+300	192	C0	À	LATIN CAPITAL LETTER A WITH GRAVE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ã	LATIN CAPITAL LETTER A WITH TILDE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	È	LATIN CAPITAL LETTER E WITH GRAVE
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ê	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ì	LATIN CAPITAL LETTER I WITH GRAVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+320	208	D0	Ŵ	LATIN CAPITAL LETTER W WITH CIRCUMFLEX
+321	209	D1	Ñ	LATIN CAPITAL LETTER N WITH TILDE
+322	210	D2	Ò	LATIN CAPITAL LETTER O WITH GRAVE
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	Ṫ	LATIN CAPITAL LETTER T WITH DOT ABOVE
+330	216	D8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+331	217	D9	Ù	LATIN CAPITAL LETTER U WITH GRAVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ý	LATIN CAPITAL LETTER Y WITH ACUTE
+336	222	DE	Ŷ	LATIN CAPITAL LETTER Y WITH CIRCUMFLEX
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	à	LATIN SMALL LETTER A WITH GRAVE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ã	LATIN SMALL LETTER A WITH TILDE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	è	LATIN SMALL LETTER E WITH GRAVE
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ê	LATIN SMALL LETTER E WITH CIRCUMFLEX
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ì	LATIN SMALL LETTER I WITH GRAVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+360	240	F0	ŵ	LATIN SMALL LETTER W WITH CIRCUMFLEX
+361	241	F1	ñ	LATIN SMALL LETTER N WITH TILDE
+362	242	F2	ò	LATIN SMALL LETTER O WITH GRAVE
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	ṫ	LATIN SMALL LETTER T WITH DOT ABOVE
+370	248	F8	ø	LATIN SMALL LETTER O WITH STROKE
+371	249	F9	ù	LATIN SMALL LETTER U WITH GRAVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ý	LATIN SMALL LETTER Y WITH ACUTE
+376	254	FE	ŷ	LATIN SMALL LETTER Y WITH CIRCUMFLEX
+377	255	FF	ÿ	LATIN SMALL LETTER Y WITH DIAERESIS
+.TE
+.SH NOTES
+ISO/IEC\~8859-14 is also known as Latin-8.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-15.7 b/man/man7/iso_8859-15.7
new file mode 100644
index 000000000..228f58ecd
--- /dev/null
+++ b/man/man7/iso_8859-15.7
@@ -0,0 +1,149 @@
+'\" t
+.\" Copyright 1993-1995 Daniel Quinlan (quinlan@yggdrasil.com)
+.\" Copyright 1999      Dimitri Papadopoulos (dpo@club-internet.fr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-15 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-15 \- ISO/IEC\~8859-15 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-15 encodes the
+characters used in many West European languages and adds the Euro sign.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-15 characters
+The following table displays the characters in ISO/IEC\~8859-15 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	¡	INVERTED EXCLAMATION MARK
+242	162	A2	¢	CENT SIGN
+243	163	A3	£	POUND SIGN
+244	164	A4	€	EURO SIGN
+245	165	A5	¥	YEN SIGN
+246	166	A6	Š	LATIN CAPITAL LETTER S WITH CARON
+247	167	A7	§	SECTION SIGN
+250	168	A8	š	LATIN SMALL LETTER S WITH CARON
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	ª	FEMININE ORDINAL INDICATOR
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	¯	MACRON
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	Ž	LATIN CAPITAL LETTER Z WITH CARON
+265	181	B5	µ	MICRO SIGN
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	ž	LATIN SMALL LETTER Z WITH CARON
+271	185	B9	¹	SUPERSCRIPT ONE
+272	186	BA	º	MASCULINE ORDINAL INDICATOR
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	Œ	LATIN CAPITAL LIGATURE OE
+275	189	BD	œ	LATIN SMALL LIGATURE OE
+276	190	BE	Ÿ	LATIN CAPITAL LETTER Y WITH DIAERESIS
+277	191	BF	¿	INVERTED QUESTION MARK
+300	192	C0	À	LATIN CAPITAL LETTER A WITH GRAVE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ã	LATIN CAPITAL LETTER A WITH TILDE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	È	LATIN CAPITAL LETTER E WITH GRAVE
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ê	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ì	LATIN CAPITAL LETTER I WITH GRAVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+320	208	D0	Ð	LATIN CAPITAL LETTER ETH
+321	209	D1	Ñ	LATIN CAPITAL LETTER N WITH TILDE
+322	210	D2	Ò	LATIN CAPITAL LETTER O WITH GRAVE
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+331	217	D9	Ù	LATIN CAPITAL LETTER U WITH GRAVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ý	LATIN CAPITAL LETTER Y WITH ACUTE
+336	222	DE	Þ	LATIN CAPITAL LETTER THORN
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	à	LATIN SMALL LETTER A WITH GRAVE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ã	LATIN SMALL LETTER A WITH TILDE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	è	LATIN SMALL LETTER E WITH GRAVE
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ê	LATIN SMALL LETTER E WITH CIRCUMFLEX
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ì	LATIN SMALL LETTER I WITH GRAVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+360	240	F0	ð	LATIN SMALL LETTER ETH
+361	241	F1	ñ	LATIN SMALL LETTER N WITH TILDE
+362	242	F2	ò	LATIN SMALL LETTER O WITH GRAVE
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ø	LATIN SMALL LETTER O WITH STROKE
+371	249	F9	ù	LATIN SMALL LETTER U WITH GRAVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ý	LATIN SMALL LETTER Y WITH ACUTE
+376	254	FE	þ	LATIN SMALL LETTER THORN
+377	255	FF	ÿ	LATIN SMALL LETTER Y WITH DIAERESIS
+.TE
+.SH NOTES
+ISO/IEC\~8859-15 is also known as Latin-9 (or sometimes as Latin-0).
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR cp1252 (7),
+.BR iso_8859\-1 (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-16.7 b/man/man7/iso_8859-16.7
new file mode 100644
index 000000000..2137f03dc
--- /dev/null
+++ b/man/man7/iso_8859-16.7
@@ -0,0 +1,147 @@
+'\" t
+.\" Copyright 2002 Ionel Mugurel Ciobîcă (IMCiobica@netscape.net)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-16 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-16 \- ISO/IEC\~8859-16 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-16 encodes the
+Latin characters used in Southeast European languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-16 characters
+The following table displays the characters in ISO/IEC\~8859-16 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ą	LATIN CAPITAL LETTER A WITH OGONEK
+242	162	A2	ą	LATIN SMALL LETTER A WITH OGONEK
+243	163	A3	Ł	LATIN CAPITAL LETTER L WITH STROKE
+244	164	A4	€	EURO SIGN
+245	165	A5	„	DOUBLE LOW-9 QUOTATION MARK
+246	166	A6	Š	LATIN CAPITAL LETTER S WITH CARON
+247	167	A7	§	SECTION SIGN
+250	168	A8	š	LATIN SMALL LETTER S WITH CARON
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	Ș	LATIN CAPITAL LETTER S WITH COMMA BELOW
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	Ź	LATIN CAPITAL LETTER Z WITH ACUTE
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	ź	LATIN SMALL LETTER Z WITH ACUTE
+257	175	AF	Ż	LATIN CAPITAL LETTER Z WITH DOT ABOVE
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	Č	LATIN CAPITAL LETTER C WITH CARON
+263	179	B3	ł	LATIN SMALL LETTER L WITH STROKE
+264	180	B4	Ž	LATIN CAPITAL LETTER Z WITH CARON
+265	181	B5	”	LEFT DOUBLE QUOTATION MARK
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	ž	LATIN SMALL LETTER Z WITH CARON
+271	185	B9	č	LATIN SMALL LETTER C WITH CARON
+272	186	BA	ș	LATIN SMALL LETTER S WITH COMMA BELOW
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	Œ	LATIN CAPITAL LIGATURE OE
+275	189	BD	œ	LATIN SMALL LIGATURE OE
+276	190	BE	Ÿ	LATIN CAPITAL LETTER Y WITH DIAERESIS
+277	191	BF	ż	LATIN SMALL LETTER Z WITH DOT ABOVE
+300	192	C0	À	LATIN CAPITAL LETTER A WITH GRAVE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ă	LATIN CAPITAL LETTER A WITH BREVE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Ć	LATIN CAPITAL LETTER C WITH ACUTE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	È	LATIN CAPITAL LETTER E WITH GRAVE
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ê	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ì	LATIN CAPITAL LETTER I WITH GRAVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+320	208	D0	Đ	LATIN CAPITAL LETTER D WITH STROKE
+321	209	D1	Ń	LATIN CAPITAL LETTER N WITH ACUTE
+322	210	D2	Ò	LATIN CAPITAL LETTER O WITH GRAVE
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Ő	LATIN CAPITAL LETTER O WITH DOUBLE ACUTE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	Ś	LATIN CAPITAL LETTER S WITH ACUTE
+330	216	D8	Ű	LATIN CAPITAL LETTER U WITH DOUBLE ACUTE
+331	217	D9	Ù	LATIN CAPITAL LETTER U WITH GRAVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ę	LATIN CAPITAL LETTER E WITH OGONEK
+336	222	DE	Ț	LATIN CAPITAL LETTER T WITH COMMA BELOW
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	à	LATIN SMALL LETTER A WITH GRAVE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ă	LATIN SMALL LETTER A WITH BREVE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	ć	LATIN SMALL LETTER C WITH ACUTE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	è	LATIN SMALL LETTER E WITH GRAVE
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ê	LATIN SMALL LETTER E WITH CIRCUMFLEX
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ì	LATIN SMALL LETTER I WITH GRAVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+360	240	F0	đ	LATIN SMALL LETTER D WITH STROKE
+361	241	F1	ń	LATIN SMALL LETTER N WITH ACUTE
+362	242	F2	ò	LATIN SMALL LETTER O WITH GRAVE
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	ő	LATIN SMALL LETTER O WITH DOUBLE ACUTE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	ś	LATIN SMALL LETTER S WITH ACUTE
+370	248	F8	ű	LATIN SMALL LETTER U WITH DOUBLE ACUTE
+371	249	F9	ù	LATIN SMALL LETTER U WITH GRAVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ę	LATIN SMALL LETTER E WITH OGONEK
+376	254	FE	ț	LATIN SMALL LETTER T WITH COMMA BELOW
+377	255	FF	ÿ	LATIN SMALL LETTER Y WITH DIAERESIS
+.TE
+.SH NOTES
+ISO/IEC\~8859-16 is also known as Latin-10.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR iso_8859\-3 (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-2.7 b/man/man7/iso_8859-2.7
new file mode 100644
index 000000000..8a93b04fd
--- /dev/null
+++ b/man/man7/iso_8859-2.7
@@ -0,0 +1,151 @@
+'\" t
+.\" Copyright 1999 Roman Maurer (roman.maurer@hermes.si)
+.\" Copyright 1993-1995 Daniel Quinlan (quinlan@yggdrasil.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Slightly rearranged, aeb, 950713
+.\" Updated, dpo, 990531
+.TH ISO_8859-2 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-2 \- ISO/IEC\~8859-2 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-2 encodes the
+Latin characters used in many Central and East European languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-2 characters
+The following table displays the characters in ISO/IEC\~8859-2 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ą	LATIN CAPITAL LETTER A WITH OGONEK
+242	162	A2	˘	BREVE
+243	163	A3	Ł	LATIN CAPITAL LETTER L WITH STROKE
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	Ľ	LATIN CAPITAL LETTER L WITH CARON
+246	166	A6	Ś	LATIN CAPITAL LETTER S WITH ACUTE
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	Š	LATIN CAPITAL LETTER S WITH CARON
+252	170	AA	Ş	LATIN CAPITAL LETTER S WITH CEDILLA
+253	171	AB	Ť	LATIN CAPITAL LETTER T WITH CARON
+254	172	AC	Ź	LATIN CAPITAL LETTER Z WITH ACUTE
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	Ž	LATIN CAPITAL LETTER Z WITH CARON
+257	175	AF	Ż	LATIN CAPITAL LETTER Z WITH DOT ABOVE
+260	176	B0	°	DEGREE SIGN
+261	177	B1	ą	LATIN SMALL LETTER A WITH OGONEK
+262	178	B2	˛	OGONEK
+263	179	B3	ł	LATIN SMALL LETTER L WITH STROKE
+264	180	B4	´	ACUTE ACCENT
+265	181	B5	ľ	LATIN SMALL LETTER L WITH CARON
+266	182	B6	ś	LATIN SMALL LETTER S WITH ACUTE
+267	183	B7	ˇ	CARON
+270	184	B8	¸	CEDILLA
+271	185	B9	š	LATIN SMALL LETTER S WITH CARON
+272	186	BA	ş	LATIN SMALL LETTER S WITH CEDILLA
+273	187	BB	ť	LATIN SMALL LETTER T WITH CARON
+274	188	BC	ź	LATIN SMALL LETTER Z WITH ACUTE
+275	189	BD	˝	DOUBLE ACUTE ACCENT
+276	190	BE	ž	LATIN SMALL LETTER Z WITH CARON
+277	191	BF	ż	LATIN SMALL LETTER Z WITH DOT ABOVE
+300	192	C0	Ŕ	LATIN CAPITAL LETTER R WITH ACUTE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ă	LATIN CAPITAL LETTER A WITH BREVE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Ĺ	LATIN CAPITAL LETTER L WITH ACUTE
+306	198	C6	Ć	LATIN CAPITAL LETTER C WITH ACUTE
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	Č	LATIN CAPITAL LETTER C WITH CARON
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ę	LATIN CAPITAL LETTER E WITH OGONEK
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ě	LATIN CAPITAL LETTER E WITH CARON
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ď	LATIN CAPITAL LETTER D WITH CARON
+320	208	D0	Đ	LATIN CAPITAL LETTER D WITH STROKE
+321	209	D1	Ń	LATIN CAPITAL LETTER N WITH ACUTE
+322	210	D2	Ň	LATIN CAPITAL LETTER N WITH CARON
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Ő	LATIN CAPITAL LETTER O WITH DOUBLE ACUTE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ř	LATIN CAPITAL LETTER R WITH CARON
+331	217	D9	Ů	LATIN CAPITAL LETTER U WITH RING ABOVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Ű	LATIN CAPITAL LETTER U WITH DOUBLE ACUTE
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ý	LATIN CAPITAL LETTER Y WITH ACUTE
+336	222	DE	Ţ	LATIN CAPITAL LETTER T WITH CEDILLA
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	ŕ	LATIN SMALL LETTER R WITH ACUTE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ă	LATIN SMALL LETTER A WITH BREVE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	ĺ	LATIN SMALL LETTER L WITH ACUTE
+346	230	E6	ć	LATIN SMALL LETTER C WITH ACUTE
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	č	LATIN SMALL LETTER C WITH CARON
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ę	LATIN SMALL LETTER E WITH OGONEK
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ě	LATIN SMALL LETTER E WITH CARON
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ď	LATIN SMALL LETTER D WITH CARON
+360	240	F0	đ	LATIN SMALL LETTER D WITH STROKE
+361	241	F1	ń	LATIN SMALL LETTER N WITH ACUTE
+362	242	F2	ň	LATIN SMALL LETTER N WITH CARON
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	ő	LATIN SMALL LETTER O WITH DOUBLE ACUTE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ř	LATIN SMALL LETTER R WITH CARON
+371	249	F9	ů	LATIN SMALL LETTER U WITH RING ABOVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	ű	LATIN SMALL LETTER U WITH DOUBLE ACUTE
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ý	LATIN SMALL LETTER Y WITH ACUTE
+376	254	FE	ţ	LATIN SMALL LETTER T WITH CEDILLA
+377	255	FF	˙	DOT ABOVE
+.TE
+.SH NOTES
+ISO/IEC\~8859-2 is also known as Latin-2.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR iso_8859\-1 (7),
+.BR iso_8859\-16 (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-3.7 b/man/man7/iso_8859-3.7
new file mode 100644
index 000000000..22c0da332
--- /dev/null
+++ b/man/man7/iso_8859-3.7
@@ -0,0 +1,139 @@
+'\" t
+.\" Copyright 2009  Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-3 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-3 \- ISO/IEC\~8859-3 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-3 encodes the
+characters used in certain Southeast European languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-3 characters
+The following table displays the characters in ISO/IEC\~8859-3 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ħ	LATIN CAPITAL LETTER H WITH STROKE
+242	162	A2	˘	BREVE
+243	163	A3	£	POUND SIGN
+244	164	A4	¤	CURRENCY SIGN
+246	166	A6	Ĥ	LATIN CAPITAL LETTER H WITH CIRCUMFLEX
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	İ	LATIN CAPITAL LETTER I WITH DOT ABOVE
+252	170	AA	Ş	LATIN CAPITAL LETTER S WITH CEDILLA
+253	171	AB	Ğ	LATIN CAPITAL LETTER G WITH BREVE
+254	172	AC	Ĵ	LATIN CAPITAL LETTER J WITH CIRCUMFLEX
+255	173	AD	­	SOFT HYPHEN
+257	175	AF	Ż	LATIN CAPITAL LETTER Z WITH DOT ABOVE
+260	176	B0	°	DEGREE SIGN
+261	177	B1	ħ	LATIN SMALL LETTER H WITH STROKE
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	´	ACUTE ACCENT
+265	181	B5	µ	MICRO SIGN
+266	182	B6	ĥ	LATIN SMALL LETTER H WITH CIRCUMFLEX
+267	183	B7	·	MIDDLE DOT
+270	184	B8	¸	CEDILLA
+271	185	B9	ı	LATIN SMALL LETTER DOTLESS I
+272	186	BA	ş	LATIN SMALL LETTER S WITH CEDILLA
+273	187	BB	ğ	LATIN SMALL LETTER G WITH BREVE
+274	188	BC	ĵ	LATIN SMALL LETTER J WITH CIRCUMFLEX
+275	189	BD	½	VULGAR FRACTION ONE HALF
+277	191	BF	ż	LATIN SMALL LETTER Z WITH DOT ABOVE
+300	192	C0	À	LATIN CAPITAL LETTER A WITH GRAVE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Ċ	LATIN CAPITAL LETTER C WITH DOT ABOVE
+306	198	C6	Ĉ	LATIN CAPITAL LETTER C WITH CIRCUMFLEX
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	È	LATIN CAPITAL LETTER E WITH GRAVE
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ê	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ì	LATIN CAPITAL LETTER I WITH GRAVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+321	209	D1	Ñ	LATIN CAPITAL LETTER N WITH TILDE
+322	210	D2	Ò	LATIN CAPITAL LETTER O WITH GRAVE
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Ġ	LATIN CAPITAL LETTER G WITH DOT ABOVE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ĝ	LATIN CAPITAL LETTER G WITH CIRCUMFLEX
+331	217	D9	Ù	LATIN CAPITAL LETTER U WITH GRAVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ŭ	LATIN CAPITAL LETTER U WITH BREVE
+336	222	DE	Ŝ	LATIN CAPITAL LETTER S WITH CIRCUMFLEX
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	à	LATIN SMALL LETTER A WITH GRAVE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	ċ	LATIN SMALL LETTER C WITH DOT ABOVE
+346	230	E6	ĉ	LATIN SMALL LETTER C WITH CIRCUMFLEX
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	è	LATIN SMALL LETTER E WITH GRAVE
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ê	LATIN SMALL LETTER E WITH CIRCUMFLEX
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ì	LATIN SMALL LETTER I WITH GRAVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+361	241	F1	ñ	LATIN SMALL LETTER N WITH TILDE
+362	242	F2	ò	LATIN SMALL LETTER O WITH GRAVE
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	ġ	LATIN SMALL LETTER G WITH DOT ABOVE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ĝ	LATIN SMALL LETTER G WITH CIRCUMFLEX
+371	249	F9	ù	LATIN SMALL LETTER U WITH GRAVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ŭ	LATIN SMALL LETTER U WITH BREVE
+376	254	FE	ŝ	LATIN SMALL LETTER S WITH CIRCUMFLEX
+377	255	FF	˙	DOT ABOVE
+.TE
+.SH NOTES
+ISO/IEC\~8859-3 is also known as Latin-3.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-4.7 b/man/man7/iso_8859-4.7
new file mode 100644
index 000000000..8d2cb02e9
--- /dev/null
+++ b/man/man7/iso_8859-4.7
@@ -0,0 +1,146 @@
+'\" t
+.\" Copyright 2009  Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-4 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-4 \- ISO/IEC\~8859-4 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-4 encodes the
+characters used in Scandinavian and Baltic languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-4 characters
+The following table displays the characters in ISO/IEC\~8859-4 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ą	LATIN CAPITAL LETTER A WITH OGONEK
+242	162	A2	ĸ	LATIN SMALL LETTER KRA (Greenlandic)
+243	163	A3	Ŗ	LATIN CAPITAL LETTER R WITH CEDILLA
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	Ĩ	LATIN CAPITAL LETTER I WITH TILDE
+246	166	A6	Ļ	LATIN CAPITAL LETTER L WITH CEDILLA
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	Š	LATIN CAPITAL LETTER S WITH CARON
+252	170	AA	Ē	LATIN CAPITAL LETTER E WITH MACRON
+253	171	AB	Ģ	LATIN CAPITAL LETTER G WITH CEDILLA
+254	172	AC	Ŧ	LATIN CAPITAL LETTER T WITH STROKE
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	Ž	LATIN CAPITAL LETTER Z WITH CARON
+257	175	AF	¯	MACRON
+260	176	B0	°	DEGREE SIGN
+261	177	B1	ą	LATIN SMALL LETTER A WITH OGONEK
+262	178	B2	˛	OGONEK
+263	179	B3	ŗ	LATIN SMALL LETTER R WITH CEDILLA
+264	180	B4	´	ACUTE ACCENT
+265	181	B5	ĩ	LATIN SMALL LETTER I WITH TILDE
+266	182	B6	ļ	LATIN SMALL LETTER L WITH CEDILLA
+267	183	B7	ˇ	CARON
+270	184	B8	¸	CEDILLA
+271	185	B9	š	LATIN SMALL LETTER S WITH CARON
+272	186	BA	ē	LATIN SMALL LETTER E WITH MACRON
+273	187	BB	ģ	LATIN SMALL LETTER G WITH CEDILLA
+274	188	BC	ŧ	LATIN SMALL LETTER T WITH STROKE
+275	189	BD	Ŋ	LATIN CAPITAL LETTER ENG
+276	190	BE	ž	LATIN SMALL LETTER Z WITH CARON
+277	191	BF	ŋ	LATIN SMALL LETTER ENG
+300	192	C0	Ā	LATIN CAPITAL LETTER A WITH MACRON
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ã	LATIN CAPITAL LETTER A WITH TILDE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Į	LATIN CAPITAL LETTER I WITH OGONEK
+310	200	C8	Č	LATIN CAPITAL LETTER C WITH CARON
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ę	LATIN CAPITAL LETTER E WITH OGONEK
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ė	LATIN CAPITAL LETTER E WITH DOT ABOVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ī	LATIN CAPITAL LETTER I WITH MACRON
+320	208	D0	Đ	LATIN CAPITAL LETTER D WITH STROKE
+321	209	D1	Ņ	LATIN CAPITAL LETTER N WITH CEDILLA
+322	210	D2	Ō	LATIN CAPITAL LETTER O WITH MACRON
+323	211	D3	Ķ	LATIN CAPITAL LETTER K WITH CEDILLA
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+331	217	D9	Ų	LATIN CAPITAL LETTER U WITH OGONEK
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	Ũ	LATIN CAPITAL LETTER U WITH TILDE
+336	222	DE	Ū	LATIN CAPITAL LETTER U WITH MACRON
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	ā	LATIN SMALL LETTER A WITH MACRON
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ã	LATIN SMALL LETTER A WITH TILDE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	į	LATIN SMALL LETTER I WITH OGONEK
+350	232	E8	č	LATIN SMALL LETTER C WITH CARON
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ę	LATIN SMALL LETTER E WITH OGONEK
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ė	LATIN SMALL LETTER E WITH DOT ABOVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ī	LATIN SMALL LETTER I WITH MACRON
+360	240	F0	đ	LATIN SMALL LETTER D WITH STROKE
+361	241	F1	ņ	LATIN SMALL LETTER N WITH CEDILLA
+362	242	F2	ō	LATIN SMALL LETTER O WITH MACRON
+363	243	F3	ķ	LATIN SMALL LETTER K WITH CEDILLA
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ø	LATIN SMALL LETTER O WITH STROKE
+371	249	F9	ų	LATIN SMALL LETTER U WITH OGONEK
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ũ	LATIN SMALL LETTER U WITH TILDE
+376	254	FE	ū	LATIN SMALL LETTER U WITH MACRON
+377	255	FF	˙	DOT ABOVE
+.TE
+.SH NOTES
+ISO/IEC\~8859-4 is also known as Latin-4.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-5.7 b/man/man7/iso_8859-5.7
new file mode 100644
index 000000000..196d8c216
--- /dev/null
+++ b/man/man7/iso_8859-5.7
@@ -0,0 +1,151 @@
+'\" t
+.\" Copyright 2009   Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-5 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-5 \- ISO/IEC\~8859-5 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-5 encodes the
+Cyrillic characters used in many East European languages.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-5 characters
+The following table displays the characters in ISO/IEC\~8859-5 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	Ё	CYRILLIC CAPITAL LETTER IO
+242	162	A2	Ђ	CYRILLIC CAPITAL LETTER DJE
+243	163	A3	Ѓ	CYRILLIC CAPITAL LETTER GJE
+244	164	A4	Є	CYRILLIC CAPITAL LETTER UKRAINIAN IE
+245	165	A5	Ѕ	CYRILLIC CAPITAL LETTER DZE
+246	166	A6	І	T{
+CYRILLIC CAPITAL LETTER
+.br
+BYELORUSSIAN-UKRAINIAN I
+T}
+247	167	A7	Ї	CYRILLIC CAPITAL LETTER YI
+250	168	A8	Ј	CYRILLIC CAPITAL LETTER JE
+251	169	A9	Љ	CYRILLIC CAPITAL LETTER LJE
+252	170	AA	Њ	CYRILLIC CAPITAL LETTER NJE
+253	171	AB	Ћ	CYRILLIC CAPITAL LETTER TSHE
+254	172	AC	Ќ	CYRILLIC CAPITAL LETTER KJE
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	Ў	CYRILLIC CAPITAL LETTER SHORT U
+257	175	AF	Џ	CYRILLIC CAPITAL LETTER DZHE
+260	176	B0	А	CYRILLIC CAPITAL LETTER A
+261	177	B1	Б	CYRILLIC CAPITAL LETTER BE
+262	178	B2	В	CYRILLIC CAPITAL LETTER VE
+263	179	B3	Г	CYRILLIC CAPITAL LETTER GHE
+264	180	B4	Д	CYRILLIC CAPITAL LETTER DE
+265	181	B5	Е	CYRILLIC CAPITAL LETTER IE
+266	182	B6	Ж	CYRILLIC CAPITAL LETTER ZHE
+267	183	B7	З	CYRILLIC CAPITAL LETTER ZE
+270	184	B8	И	CYRILLIC CAPITAL LETTER I
+271	185	B9	Й	CYRILLIC CAPITAL LETTER SHORT I
+272	186	BA	К	CYRILLIC CAPITAL LETTER KA
+273	187	BB	Л	CYRILLIC CAPITAL LETTER EL
+274	188	BC	М	CYRILLIC CAPITAL LETTER EM
+275	189	BD	Н	CYRILLIC CAPITAL LETTER EN
+276	190	BE	О	CYRILLIC CAPITAL LETTER O
+277	191	BF	П	CYRILLIC CAPITAL LETTER PE
+300	192	C0	Р	CYRILLIC CAPITAL LETTER ER
+301	193	C1	С	CYRILLIC CAPITAL LETTER ES
+302	194	C2	Т	CYRILLIC CAPITAL LETTER TE
+303	195	C3	У	CYRILLIC CAPITAL LETTER U
+304	196	C4	Ф	CYRILLIC CAPITAL LETTER EF
+305	197	C5	Х	CYRILLIC CAPITAL LETTER HA
+306	198	C6	Ц	CYRILLIC CAPITAL LETTER TSE
+307	199	C7	Ч	CYRILLIC CAPITAL LETTER CHE
+310	200	C8	Ш	CYRILLIC CAPITAL LETTER SHA
+311	201	C9	Щ	CYRILLIC CAPITAL LETTER SHCHA
+312	202	CA	Ъ	CYRILLIC CAPITAL LETTER HARD SIGN
+313	203	CB	Ы	CYRILLIC CAPITAL LETTER YERU
+314	204	CC	Ь	CYRILLIC CAPITAL LETTER SOFT SIGN
+315	205	CD	Э	CYRILLIC CAPITAL LETTER E
+316	206	CE	Ю	CYRILLIC CAPITAL LETTER YU
+317	207	CF	Я	CYRILLIC CAPITAL LETTER YA
+320	208	D0	а	CYRILLIC SMALL LETTER A
+321	209	D1	б	CYRILLIC SMALL LETTER BE
+322	210	D2	в	CYRILLIC SMALL LETTER VE
+323	211	D3	г	CYRILLIC SMALL LETTER GHE
+324	212	D4	д	CYRILLIC SMALL LETTER DE
+325	213	D5	е	CYRILLIC SMALL LETTER IE
+326	214	D6	ж	CYRILLIC SMALL LETTER ZHE
+327	215	D7	з	CYRILLIC SMALL LETTER ZE
+330	216	D8	и	CYRILLIC SMALL LETTER I
+331	217	D9	й	CYRILLIC SMALL LETTER SHORT I
+332	218	DA	к	CYRILLIC SMALL LETTER KA
+333	219	DB	л	CYRILLIC SMALL LETTER EL
+334	220	DC	м	CYRILLIC SMALL LETTER EM
+335	221	DD	н	CYRILLIC SMALL LETTER EN
+336	222	DE	о	CYRILLIC SMALL LETTER O
+337	223	DF	п	CYRILLIC SMALL LETTER PE
+340	224	E0	р	CYRILLIC SMALL LETTER ER
+341	225	E1	с	CYRILLIC SMALL LETTER ES
+342	226	E2	т	CYRILLIC SMALL LETTER TE
+343	227	E3	у	CYRILLIC SMALL LETTER U
+344	228	E4	ф	CYRILLIC SMALL LETTER EF
+345	229	E5	х	CYRILLIC SMALL LETTER HA
+346	230	E6	ц	CYRILLIC SMALL LETTER TSE
+347	231	E7	ч	CYRILLIC SMALL LETTER CHE
+350	232	E8	ш	CYRILLIC SMALL LETTER SHA
+351	233	E9	щ	CYRILLIC SMALL LETTER SHCHA
+352	234	EA	ъ	CYRILLIC SMALL LETTER HARD SIGN
+353	235	EB	ы	CYRILLIC SMALL LETTER YERU
+354	236	EC	ь	CYRILLIC SMALL LETTER SOFT SIGN
+355	237	ED	э	CYRILLIC SMALL LETTER E
+356	238	EE	ю	CYRILLIC SMALL LETTER YU
+357	239	EF	я	CYRILLIC SMALL LETTER YA
+360	240	F0	№	NUMERO SIGN
+361	241	F1	ё	CYRILLIC SMALL LETTER IO
+362	242	F2	ђ	CYRILLIC SMALL LETTER DJE
+363	243	F3	ѓ	CYRILLIC SMALL LETTER GJE
+364	244	F4	є	CYRILLIC SMALL LETTER UKRAINIAN IE
+365	245	F5	ѕ	CYRILLIC SMALL LETTER DZE
+366	246	F6	і	CYRILLIC SMALL LETTER BYELORUSSIAN-UKRAINIAN I
+367	247	F7	ї	CYRILLIC SMALL LETTER YI
+370	248	F8	ј	CYRILLIC SMALL LETTER JE
+371	249	F9	љ	CYRILLIC SMALL LETTER LJE
+372	250	FA	њ	CYRILLIC SMALL LETTER NJE
+373	251	FB	ј	CYRILLIC SMALL LETTER TSHE
+374	252	FC	ќ	CYRILLIC SMALL LETTER KJE
+375	253	FD	§	SECTION SIGN
+376	254	FE	ў	CYRILLIC SMALL LETTER SHORT U
+377	255	FF	џ	CYRILLIC SMALL LETTER DZHE
+.TE
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR cp1251 (7),
+.BR koi8\-r (7),
+.BR koi8\-u (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-6.7 b/man/man7/iso_8859-6.7
new file mode 100644
index 000000000..60115b577
--- /dev/null
+++ b/man/man7/iso_8859-6.7
@@ -0,0 +1,104 @@
+'\" t
+.\" Copyright 2009  Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-6 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-6
+\-
+ISO/IEC\~8859-6 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-6 encodes the
+characters used in the Arabic language.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-6 characters
+The following table displays the characters in ISO/IEC\~8859-6 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+244	164	A4	¤	CURRENCY SIGN
+254	172	AC	،	ARABIC COMMA
+255	173	AD	­	SOFT HYPHEN
+273	187	BB	؛	ARABIC SEMICOLON
+277	191	BF	؟	ARABIC QUESTION MARK
+301	193	C1	ء	ARABIC LETTER HAMZA
+302	194	C2	آ	ARABIC LETTER ALEF WITH MADDA ABOVE
+303	195	C3	أ	ARABIC LETTER ALEF WITH HAMZA ABOVE
+304	196	C4	ؤ	ARABIC LETTER WAW WITH HAMZA ABOVE
+305	197	C5	إ	ARABIC LETTER ALEF WITH HAMZA BELOW
+306	198	C6	ئ	ARABIC LETTER YEH WITH HAMZA ABOVE
+307	199	C7	ا	ARABIC LETTER ALEF
+310	200	C8	ب	ARABIC LETTER BEH
+311	201	C9	ة	ARABIC LETTER TEH MARBUTA
+312	202	CA	ت	ARABIC LETTER TEH
+313	203	CB	ث	ARABIC LETTER THEH
+314	204	CC	ج	ARABIC LETTER JEEM
+315	205	CD	ح	ARABIC LETTER HAH
+316	206	CE	خ	ARABIC LETTER KHAH
+317	207	CF	د	ARABIC LETTER DAL
+320	208	D0	ذ	ARABIC LETTER THAL
+321	209	D1	ر	ARABIC LETTER REH
+322	210	D2	ز	ARABIC LETTER ZAIN
+323	211	D3	س	ARABIC LETTER SEEN
+324	212	D4	ش	ARABIC LETTER SHEEN
+325	213	D5	ص	ARABIC LETTER SAD
+326	214	D6	ض	ARABIC LETTER DAD
+327	215	D7	ط	ARABIC LETTER TAH
+330	216	D8	ظ	ARABIC LETTER ZAH
+331	217	D9	ع	ARABIC LETTER AIN
+332	218	DA	غ	ARABIC LETTER GHAIN
+340	224	E0	ـ	ARABIC TATWEEL
+341	225	E1	ف	ARABIC LETTER FEH
+342	226	E2	ق	ARABIC LETTER QAF
+343	227	E3	ك	ARABIC LETTER KAF
+344	228	E4	ل	ARABIC LETTER LAM
+345	229	E5	م	ARABIC LETTER MEEM
+346	230	E6	ن	ARABIC LETTER NOON
+347	231	E7	ه	ARABIC LETTER HEH
+350	232	E8	و	ARABIC LETTER WAW
+351	233	E9	ى	ARABIC LETTER ALEF MAKSURA
+352	234	EA	ي	ARABIC LETTER YEH
+353	235	EB	ً 	ARABIC FATHATAN
+354	236	EC	ٌ 	ARABIC DAMMATAN
+355	237	ED	ٍ 	ARABIC KASRATAN
+356	238	EE	َ 	ARABIC FATHA
+357	239	EF	ُ 	ARABIC DAMMA
+360	240	F0	ِ 	ARABIC KASRA
+361	241	F1	ّ 	ARABIC SHADDA
+362	242	F2	ْ 	ARABIC SUKUN
+.TE
+.SH NOTES
+ISO/IEC\~8859-6 lacks the glyphs required for many related languages,
+such as Urdu and Persian (Farsi).
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-7.7 b/man/man7/iso_8859-7.7
new file mode 100644
index 000000000..c56d13d4d
--- /dev/null
+++ b/man/man7/iso_8859-7.7
@@ -0,0 +1,150 @@
+'\" t
+.\" Copyright 1999      Dimitri Papadopoulos (dpo@club-internet.fr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-7 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-7 \- ISO/IEC\~8859-7 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-7 encodes the
+characters used in modern monotonic Greek.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-7 characters
+The following table displays the characters in ISO/IEC\~8859-7 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	‘	LEFT SINGLE QUOTATION MARK
+242	162	A2	’	RIGHT SINGLE QUOTATION MARK
+243	163	A3	£	POUND SIGN
+244	164	A4	€	EURO SIGN
+245	165	A5	₯	DRACHMA SIGN
+246	166	A6	¦	BROKEN BAR
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	ͺ	GREEK YPOGEGRAMMENI
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+257	175	AF	―	HORIZONTAL BAR
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	΄	GREEK TONOS
+265	181	B5	΅	GREEK DIALYTIKA TONOS
+266	182	B6	Ά	GREEK CAPITAL LETTER ALPHA WITH TONOS
+267	183	B7	·	MIDDLE DOT
+270	184	B8	Έ	GREEK CAPITAL LETTER EPSILON WITH TONOS
+271	185	B9	Ή	GREEK CAPITAL LETTER ETA WITH TONOS
+272	186	BA	Ί	GREEK CAPITAL LETTER IOTA WITH TONOS
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	Ό	GREEK CAPITAL LETTER OMICRON WITH TONOS
+275	189	BD	½	VULGAR FRACTION ONE HALF
+276	190	BE	Ύ	GREEK CAPITAL LETTER UPSILON WITH TONOS
+277	191	BF	Ώ	GREEK CAPITAL LETTER OMEGA WITH TONOS
+300	192	C0	ΐ	T{
+GREEK SMALL LETTER IOTA WITH
+.br
+DIALYTIKA AND TONOS
+T}
+301	193	C1	Α	GREEK CAPITAL LETTER ALPHA
+302	194	C2	Β	GREEK CAPITAL LETTER BETA
+303	195	C3	Γ	GREEK CAPITAL LETTER GAMMA
+304	196	C4	Δ	GREEK CAPITAL LETTER DELTA
+305	197	C5	Ε	GREEK CAPITAL LETTER EPSILON
+306	198	C6	Ζ	GREEK CAPITAL LETTER ZETA
+307	199	C7	Η	GREEK CAPITAL LETTER ETA
+310	200	C8	Θ	GREEK CAPITAL LETTER THETA
+311	201	C9	Ι	GREEK CAPITAL LETTER IOTA
+312	202	CA	Κ	GREEK CAPITAL LETTER KAPPA
+313	203	CB	Λ	GREEK CAPITAL LETTER LAMBDA
+314	204	CC	Μ	GREEK CAPITAL LETTER MU
+315	205	CD	Ν	GREEK CAPITAL LETTER NU
+316	206	CE	Ξ	GREEK CAPITAL LETTER XI
+317	207	CF	Ο	GREEK CAPITAL LETTER OMICRON
+320	208	D0	Π	GREEK CAPITAL LETTER PI
+321	209	D1	Ρ	GREEK CAPITAL LETTER RHO
+323	211	D3	Σ	GREEK CAPITAL LETTER SIGMA
+324	212	D4	Τ	GREEK CAPITAL LETTER TAU
+325	213	D5	Υ	GREEK CAPITAL LETTER UPSILON
+326	214	D6	Φ	GREEK CAPITAL LETTER PHI
+327	215	D7	Χ	GREEK CAPITAL LETTER CHI
+330	216	D8	Ψ	GREEK CAPITAL LETTER PSI
+331	217	D9	Ω	GREEK CAPITAL LETTER OMEGA
+332	218	DA	Ϊ	GREEK CAPITAL LETTER IOTA WITH DIALYTIKA
+333	219	DB	Ϋ	GREEK CAPITAL LETTER UPSILON WITH DIALYTIKA
+334	220	DC	ά	GREEK SMALL LETTER ALPHA WITH TONOS
+335	221	DD	έ	GREEK SMALL LETTER EPSILON WITH TONOS
+336	222	DE	ή	GREEK SMALL LETTER ETA WITH TONOS
+337	223	DF	ί	GREEK SMALL LETTER IOTA WITH TONOS
+340	224	E0	ΰ	T{
+GREEK SMALL LETTER UPSILON WITH
+DIALYTIKA AND TONOS
+T}
+341	225	E1	α	GREEK SMALL LETTER ALPHA
+342	226	E2	β	GREEK SMALL LETTER BETA
+343	227	E3	γ	GREEK SMALL LETTER GAMMA
+344	228	E4	δ	GREEK SMALL LETTER DELTA
+345	229	E5	ε	GREEK SMALL LETTER EPSILON
+346	230	E6	ζ	GREEK SMALL LETTER ZETA
+347	231	E7	η	GREEK SMALL LETTER ETA
+350	232	E8	θ	GREEK SMALL LETTER THETA
+351	233	E9	ι	GREEK SMALL LETTER IOTA
+352	234	EA	κ	GREEK SMALL LETTER KAPPA
+353	235	EB	λ	GREEK SMALL LETTER LAMBDA
+354	236	EC	μ	GREEK SMALL LETTER MU
+355	237	ED	ν	GREEK SMALL LETTER NU
+356	238	EE	ξ	GREEK SMALL LETTER XI
+357	239	EF	ο	GREEK SMALL LETTER OMICRON
+360	240	F0	π	GREEK SMALL LETTER PI
+361	241	F1	ρ	GREEK SMALL LETTER RHO
+362	242	F2	ς	GREEK SMALL LETTER FINAL SIGMA
+363	243	F3	σ	GREEK SMALL LETTER SIGMA
+364	244	F4	τ	GREEK SMALL LETTER TAU
+365	245	F5	υ	GREEK SMALL LETTER UPSILON
+366	246	F6	φ	GREEK SMALL LETTER PHI
+367	247	F7	χ	GREEK SMALL LETTER CHI
+370	248	F8	ψ	GREEK SMALL LETTER PSI
+371	249	F9	ω	GREEK SMALL LETTER OMEGA
+372	250	FA	ϊ	GREEK SMALL LETTER IOTA WITH DIALYTIKA
+373	251	FB	ϋ	GREEK SMALL LETTER UPSILON WITH DIALYTIKA
+374	252	FC	ό	GREEK SMALL LETTER OMICRON WITH TONOS
+375	253	FD	ύ	GREEK SMALL LETTER UPSILON WITH TONOS
+376	254	FE	ώ	GREEK SMALL LETTER OMEGA WITH TONOS
+.TE
+.SH NOTES
+ISO/IEC\~8859-7 was formerly known as ELOT-928 or ECMA-118:1986.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-8.7 b/man/man7/iso_8859-8.7
new file mode 100644
index 000000000..ad6f0340d
--- /dev/null
+++ b/man/man7/iso_8859-8.7
@@ -0,0 +1,114 @@
+'\" t
+.\" Copyright 2009   Lefteris Dimitroulakis (edimitro@tee.gr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Eli Zaretskii <eliz@gnu.org> made valuable suggestions
+.\"
+.TH ISO_8859-8 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-8 \- ISO/IEC\~8859-8 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-8 encodes the
+characters used in Modern Hebrew.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-8 characters
+The following table displays the characters in ISO/IEC\~8859-8 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+242	162	A2	¢	CENT SIGN
+243	163	A3	£	POUND SIGN
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	¥	YEN SIGN
+246	166	A6	¦	BROKEN BAR
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	×	MULTIPLICATION SIGN
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	¯	MACRON
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	´	ACUTE ACCENT
+265	181	B5	µ	MICRO SIGN
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	¸	CEDILLA
+271	185	B9	¹	SUPERSCRIPT ONE
+272	186	BA	÷	DIVISION SIGN
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	¼	VULGAR FRACTION ONE QUARTER
+275	189	BD	½	VULGAR FRACTION ONE HALF
+276	190	BE	¾	VULGAR FRACTION THREE QUARTERS
+337	223	DF	‗	DOUBLE LOW LINE
+340	224	E0	א	HEBREW LETTER ALEF
+341	225	E1	ב	HEBREW LETTER BET
+342	226	E2	ג	HEBREW LETTER GIMEL
+343	227	E3	ד	HEBREW LETTER DALET
+344	228	E4	ה	HEBREW LETTER HE
+345	229	E5	ו	HEBREW LETTER VAV
+346	230	E6	ז	HEBREW LETTER ZAYIN
+347	231	E7	ח	HEBREW LETTER HET
+350	232	E8	ט	HEBREW LETTER TET
+351	233	E9	י	HEBREW LETTER YOD
+352	234	EA	ך	HEBREW LETTER FINAL KAF
+353	235	EB	כ	HEBREW LETTER KAF
+354	236	EC	ל	HEBREW LETTER LAMED
+355	237	ED	ם	HEBREW LETTER FINAL MEM
+356	238	EE	מ	HEBREW LETTER MEM
+357	239	EF	ן	HEBREW LETTER FINAL NUN
+360	240	F0	נ	HEBREW LETTER NUN
+361	241	F1	ס	HEBREW LETTER SAMEKH
+362	242	F2	ע	HEBREW LETTER AYIN
+363	243	F3	ף	HEBREW LETTER FINAL PE
+364	244	F4	פ	HEBREW LETTER PE
+365	245	F5	ץ	HEBREW LETTER FINAL TSADI
+366	246	F6	צ	HEBREW LETTER TSADI
+367	247	F7	ק	HEBREW LETTER QOF
+370	248	F8	ר	HEBREW LETTER RESH
+371	249	F9	ש	HEBREW LETTER SHIN
+372	250	FA	ת	HEBREW LETTER TAV
+375	253	FD	‎	LEFT-TO-RIGHT MARK
+376	254	FE	‏	RIGHT-TO-LEFT MARK
+.TE
+.SH NOTES
+ISO/IEC\~8859-8 was also known as ISO-IR-138.
+ISO/IEC\~8859-8 includes neither short vowels nor diacritical marks,
+and Yiddish is not provided for.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859-9.7 b/man/man7/iso_8859-9.7
new file mode 100644
index 000000000..9858d938f
--- /dev/null
+++ b/man/man7/iso_8859-9.7
@@ -0,0 +1,146 @@
+'\" t
+.\" Copyright 2002      Dimitri Papadopoulos (dpo@club-internet.fr)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH ISO_8859-9 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iso_8859-9 \- ISO/IEC\~8859-9 character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+The ISO/IEC\~8859 standard includes several 8-bit extensions to the ASCII
+character set (also known as ISO/IEC\~646-IRV).
+ISO/IEC\~8859-9 encodes the
+characters used in Turkish.
+.SS ISO/IEC\~8859 alphabets
+The full set of ISO/IEC\~8859 alphabets includes:
+.TS
+l l.
+ISO/IEC\~8859-1	West European languages (Latin-1)
+ISO/IEC\~8859-2	Central and East European languages (Latin-2)
+ISO/IEC\~8859-3	Southeast European and miscellaneous languages (Latin-3)
+ISO/IEC\~8859-4	Scandinavian/Baltic languages (Latin-4)
+ISO/IEC\~8859-5	Latin/Cyrillic
+ISO/IEC\~8859-6	Latin/Arabic
+ISO/IEC\~8859-7	Latin/Greek
+ISO/IEC\~8859-8	Latin/Hebrew
+ISO/IEC\~8859-9	Latin-1 modification for Turkish (Latin-5)
+ISO/IEC\~8859-10	Lappish/Nordic/Eskimo languages (Latin-6)
+ISO/IEC\~8859-11	Latin/Thai
+ISO/IEC\~8859-13	Baltic Rim languages (Latin-7)
+ISO/IEC\~8859-14	Celtic (Latin-8)
+ISO/IEC\~8859-15	West European languages (Latin-9)
+ISO/IEC\~8859-16	Romanian (Latin-10)
+.TE
+.SS ISO/IEC\~8859-9 characters
+The following table displays the characters in ISO/IEC\~8859-9 that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+240	160	A0	 	NO-BREAK SPACE
+241	161	A1	¡	INVERTED EXCLAMATION MARK
+242	162	A2	¢	CENT SIGN
+243	163	A3	£	POUND SIGN
+244	164	A4	¤	CURRENCY SIGN
+245	165	A5	¥	YEN SIGN
+246	166	A6	¦	BROKEN BAR
+247	167	A7	§	SECTION SIGN
+250	168	A8	¨	DIAERESIS
+251	169	A9	©	COPYRIGHT SIGN
+252	170	AA	ª	FEMININE ORDINAL INDICATOR
+253	171	AB	«	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
+254	172	AC	¬	NOT SIGN
+255	173	AD	­	SOFT HYPHEN
+256	174	AE	®	REGISTERED SIGN
+257	175	AF	¯	MACRON
+260	176	B0	°	DEGREE SIGN
+261	177	B1	±	PLUS-MINUS SIGN
+262	178	B2	²	SUPERSCRIPT TWO
+263	179	B3	³	SUPERSCRIPT THREE
+264	180	B4	´	ACUTE ACCENT
+265	181	B5	µ	MICRO SIGN
+266	182	B6	¶	PILCROW SIGN
+267	183	B7	·	MIDDLE DOT
+270	184	B8	¸	CEDILLA
+271	185	B9	¹	SUPERSCRIPT ONE
+272	186	BA	º	MASCULINE ORDINAL INDICATOR
+273	187	BB	»	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
+274	188	BC	¼	VULGAR FRACTION ONE QUARTER
+275	189	BD	½	VULGAR FRACTION ONE HALF
+276	190	BE	¾	VULGAR FRACTION THREE QUARTERS
+277	191	BF	¿	INVERTED QUESTION MARK
+300	192	C0	À	LATIN CAPITAL LETTER A WITH GRAVE
+301	193	C1	Á	LATIN CAPITAL LETTER A WITH ACUTE
+302	194	C2	Â	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
+303	195	C3	Ã	LATIN CAPITAL LETTER A WITH TILDE
+304	196	C4	Ä	LATIN CAPITAL LETTER A WITH DIAERESIS
+305	197	C5	Å	LATIN CAPITAL LETTER A WITH RING ABOVE
+306	198	C6	Æ	LATIN CAPITAL LETTER AE
+307	199	C7	Ç	LATIN CAPITAL LETTER C WITH CEDILLA
+310	200	C8	È	LATIN CAPITAL LETTER E WITH GRAVE
+311	201	C9	É	LATIN CAPITAL LETTER E WITH ACUTE
+312	202	CA	Ê	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
+313	203	CB	Ë	LATIN CAPITAL LETTER E WITH DIAERESIS
+314	204	CC	Ì	LATIN CAPITAL LETTER I WITH GRAVE
+315	205	CD	Í	LATIN CAPITAL LETTER I WITH ACUTE
+316	206	CE	Î	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
+317	207	CF	Ï	LATIN CAPITAL LETTER I WITH DIAERESIS
+320	208	D0	Ğ	LATIN CAPITAL LETTER G WITH BREVE
+321	209	D1	Ñ	LATIN CAPITAL LETTER N WITH TILDE
+322	210	D2	Ò	LATIN CAPITAL LETTER O WITH GRAVE
+323	211	D3	Ó	LATIN CAPITAL LETTER O WITH ACUTE
+324	212	D4	Ô	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
+325	213	D5	Õ	LATIN CAPITAL LETTER O WITH TILDE
+326	214	D6	Ö	LATIN CAPITAL LETTER O WITH DIAERESIS
+327	215	D7	×	MULTIPLICATION SIGN
+330	216	D8	Ø	LATIN CAPITAL LETTER O WITH STROKE
+331	217	D9	Ù	LATIN CAPITAL LETTER U WITH GRAVE
+332	218	DA	Ú	LATIN CAPITAL LETTER U WITH ACUTE
+333	219	DB	Û	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
+334	220	DC	Ü	LATIN CAPITAL LETTER U WITH DIAERESIS
+335	221	DD	İ	LATIN CAPITAL LETTER I WITH DOT ABOVE
+336	222	DE	Ş	LATIN CAPITAL LETTER S WITH CEDILLA
+337	223	DF	ß	LATIN SMALL LETTER SHARP S
+340	224	E0	à	LATIN SMALL LETTER A WITH GRAVE
+341	225	E1	á	LATIN SMALL LETTER A WITH ACUTE
+342	226	E2	â	LATIN SMALL LETTER A WITH CIRCUMFLEX
+343	227	E3	ã	LATIN SMALL LETTER A WITH TILDE
+344	228	E4	ä	LATIN SMALL LETTER A WITH DIAERESIS
+345	229	E5	å	LATIN SMALL LETTER A WITH RING ABOVE
+346	230	E6	æ	LATIN SMALL LETTER AE
+347	231	E7	ç	LATIN SMALL LETTER C WITH CEDILLA
+350	232	E8	è	LATIN SMALL LETTER E WITH GRAVE
+351	233	E9	é	LATIN SMALL LETTER E WITH ACUTE
+352	234	EA	ê	LATIN SMALL LETTER E WITH CIRCUMFLEX
+353	235	EB	ë	LATIN SMALL LETTER E WITH DIAERESIS
+354	236	EC	ì	LATIN SMALL LETTER I WITH GRAVE
+355	237	ED	í	LATIN SMALL LETTER I WITH ACUTE
+356	238	EE	î	LATIN SMALL LETTER I WITH CIRCUMFLEX
+357	239	EF	ï	LATIN SMALL LETTER I WITH DIAERESIS
+360	240	F0	ğ	LATIN SMALL LETTER G WITH BREVE
+361	241	F1	ñ	LATIN SMALL LETTER N WITH TILDE
+362	242	F2	ò	LATIN SMALL LETTER O WITH GRAVE
+363	243	F3	ó	LATIN SMALL LETTER O WITH ACUTE
+364	244	F4	ô	LATIN SMALL LETTER O WITH CIRCUMFLEX
+365	245	F5	õ	LATIN SMALL LETTER O WITH TILDE
+366	246	F6	ö	LATIN SMALL LETTER O WITH DIAERESIS
+367	247	F7	÷	DIVISION SIGN
+370	248	F8	ø	LATIN SMALL LETTER O WITH STROKE
+371	249	F9	ù	LATIN SMALL LETTER U WITH GRAVE
+372	250	FA	ú	LATIN SMALL LETTER U WITH ACUTE
+373	251	FB	û	LATIN SMALL LETTER U WITH CIRCUMFLEX
+374	252	FC	ü	LATIN SMALL LETTER U WITH DIAERESIS
+375	253	FD	ı	LATIN SMALL LETTER DOTLESS I
+376	254	FE	ş	LATIN SMALL LETTER S WITH CEDILLA
+377	255	FF	ÿ	LATIN SMALL LETTER Y WITH DIAERESIS
+.TE
+.SH NOTES
+ISO/IEC\~8859-9 is also known as Latin-5.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/iso_8859_1.7 b/man/man7/iso_8859_1.7
new file mode 100644
index 000000000..1969dfb2f
--- /dev/null
+++ b/man/man7/iso_8859_1.7
@@ -0,0 +1 @@
+.so man7/iso_8859-1.7
diff --git a/man/man7/iso_8859_10.7 b/man/man7/iso_8859_10.7
new file mode 100644
index 000000000..9b4658f25
--- /dev/null
+++ b/man/man7/iso_8859_10.7
@@ -0,0 +1 @@
+.so man7/iso_8859-10.7
diff --git a/man/man7/iso_8859_11.7 b/man/man7/iso_8859_11.7
new file mode 100644
index 000000000..cbd4cfe7c
--- /dev/null
+++ b/man/man7/iso_8859_11.7
@@ -0,0 +1 @@
+.so man7/iso_8859-11.7
diff --git a/man/man7/iso_8859_13.7 b/man/man7/iso_8859_13.7
new file mode 100644
index 000000000..8ad23352e
--- /dev/null
+++ b/man/man7/iso_8859_13.7
@@ -0,0 +1 @@
+.so man7/iso_8859-13.7
diff --git a/man/man7/iso_8859_14.7 b/man/man7/iso_8859_14.7
new file mode 100644
index 000000000..4aa555db9
--- /dev/null
+++ b/man/man7/iso_8859_14.7
@@ -0,0 +1 @@
+.so man7/iso_8859-14.7
diff --git a/man/man7/iso_8859_15.7 b/man/man7/iso_8859_15.7
new file mode 100644
index 000000000..a4095d754
--- /dev/null
+++ b/man/man7/iso_8859_15.7
@@ -0,0 +1 @@
+.so man7/iso_8859-15.7
diff --git a/man/man7/iso_8859_16.7 b/man/man7/iso_8859_16.7
new file mode 100644
index 000000000..b9c8e9182
--- /dev/null
+++ b/man/man7/iso_8859_16.7
@@ -0,0 +1 @@
+.so man7/iso_8859-16.7
diff --git a/man/man7/iso_8859_2.7 b/man/man7/iso_8859_2.7
new file mode 100644
index 000000000..da36668dd
--- /dev/null
+++ b/man/man7/iso_8859_2.7
@@ -0,0 +1 @@
+.so man7/iso_8859-2.7
diff --git a/man/man7/iso_8859_3.7 b/man/man7/iso_8859_3.7
new file mode 100644
index 000000000..75e42ce3d
--- /dev/null
+++ b/man/man7/iso_8859_3.7
@@ -0,0 +1 @@
+.so man7/iso_8859-3.7
diff --git a/man/man7/iso_8859_4.7 b/man/man7/iso_8859_4.7
new file mode 100644
index 000000000..15a829eb3
--- /dev/null
+++ b/man/man7/iso_8859_4.7
@@ -0,0 +1 @@
+.so man7/iso_8859-4.7
diff --git a/man/man7/iso_8859_5.7 b/man/man7/iso_8859_5.7
new file mode 100644
index 000000000..1f20320e7
--- /dev/null
+++ b/man/man7/iso_8859_5.7
@@ -0,0 +1 @@
+.so man7/iso_8859-5.7
diff --git a/man/man7/iso_8859_6.7 b/man/man7/iso_8859_6.7
new file mode 100644
index 000000000..edcafdf6e
--- /dev/null
+++ b/man/man7/iso_8859_6.7
@@ -0,0 +1 @@
+.so man7/iso_8859-6.7
diff --git a/man/man7/iso_8859_7.7 b/man/man7/iso_8859_7.7
new file mode 100644
index 000000000..951384c99
--- /dev/null
+++ b/man/man7/iso_8859_7.7
@@ -0,0 +1 @@
+.so man7/iso_8859-7.7
diff --git a/man/man7/iso_8859_8.7 b/man/man7/iso_8859_8.7
new file mode 100644
index 000000000..07cf21627
--- /dev/null
+++ b/man/man7/iso_8859_8.7
@@ -0,0 +1 @@
+.so man7/iso_8859-8.7
diff --git a/man/man7/iso_8859_9.7 b/man/man7/iso_8859_9.7
new file mode 100644
index 000000000..0fcc7d463
--- /dev/null
+++ b/man/man7/iso_8859_9.7
@@ -0,0 +1 @@
+.so man7/iso_8859-9.7
diff --git a/man/man7/kernel_lockdown.7 b/man/man7/kernel_lockdown.7
new file mode 100644
index 000000000..1dcb583d4
--- /dev/null
+++ b/man/man7/kernel_lockdown.7
@@ -0,0 +1,109 @@
+.\"
+.\" Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH kernel_lockdown 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+kernel_lockdown \- kernel image access prevention feature
+.SH DESCRIPTION
+The Kernel Lockdown feature is designed to prevent both direct and indirect
+access to a running kernel image, attempting to protect against unauthorized
+modification of the kernel image and to prevent access to security and
+cryptographic data located in kernel memory, whilst still permitting driver
+modules to be loaded.
+.P
+If a prohibited or restricted feature is accessed or used, the kernel will emit
+a message that looks like:
+.P
+.in +4n
+.EX
+Lockdown: X: Y is restricted, see man kernel_lockdown.7
+.EE
+.in
+.P
+where X indicates the process name and Y indicates what is restricted.
+.P
+On an EFI-enabled x86 or arm64 machine, lockdown will be automatically enabled
+if the system boots in EFI Secure Boot mode.
+.\"
+.SS Coverage
+When lockdown is in effect, a number of features are disabled or have their
+use restricted.
+This includes special device files and kernel services that allow
+direct access of the kernel image:
+.P
+.RS
+/dev/mem
+.br
+/dev/kmem
+.br
+/dev/kcore
+.br
+/dev/ioports
+.br
+BPF
+.br
+kprobes
+.RE
+.P
+and the ability to directly configure and control devices, so as to prevent
+the use of a device to access or modify a kernel image:
+.IP \[bu] 3
+The use of module parameters that directly specify hardware parameters to
+drivers through the kernel command line or when loading a module.
+.IP \[bu]
+The use of direct PCI BAR access.
+.IP \[bu]
+The use of the ioperm and iopl instructions on x86.
+.IP \[bu]
+The use of the KD*IO console ioctls.
+.IP \[bu]
+The use of the TIOCSSERIAL serial ioctl.
+.IP \[bu]
+The alteration of MSR registers on x86.
+.IP \[bu]
+The replacement of the PCMCIA CIS.
+.IP \[bu]
+The overriding of ACPI tables.
+.IP \[bu]
+The use of ACPI error injection.
+.IP \[bu]
+The specification of the ACPI RDSP address.
+.IP \[bu]
+The use of ACPI custom methods.
+.P
+Certain facilities are restricted:
+.IP \[bu] 3
+Only validly signed modules may be loaded (waived if the module file being
+loaded is vouched for by IMA appraisal).
+.IP \[bu]
+Only validly signed binaries may be kexec'd (waived if the binary image file
+to be executed is vouched for by IMA appraisal).
+.IP \[bu]
+Unencrypted hibernation/suspend to swap are disallowed as the kernel image is
+saved to a medium that can then be accessed.
+.IP \[bu]
+Use of debugfs is not permitted as this allows a whole range of actions
+including direct configuration of, access to and driving of hardware.
+.IP \[bu]
+IMA requires the addition of the "secure_boot" rules to the policy,
+whether or not they are specified on the command line,
+for both the built-in and custom policies in secure boot lockdown mode.
+.SH VERSIONS
+The Kernel Lockdown feature was added in Linux 5.4.
+.SH NOTES
+The Kernel Lockdown feature is enabled by CONFIG_SECURITY_LOCKDOWN_LSM.
+The
+.I lsm=lsm1,...,lsmN
+command line parameter controls the sequence of the initialization of
+Linux Security Modules.
+It must contain the string
+.I lockdown
+to enable the Kernel Lockdown feature.
+If the command line parameter is not specified,
+the initialization falls back to the value of the deprecated
+.I security=
+command line parameter and further to the value of CONFIG_LSM.
+.\" commit 000d388ed3bbed745f366ce71b2bb7c2ee70f449
diff --git a/man/man7/keyrings.7 b/man/man7/keyrings.7
new file mode 100644
index 000000000..96683f545
--- /dev/null
+++ b/man/man7/keyrings.7
@@ -0,0 +1,901 @@
+.\" Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\" and Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH keyrings 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+keyrings \- in-kernel key management and retention facility
+.SH DESCRIPTION
+The Linux key-management facility
+is primarily a way for various kernel components
+to retain or cache security data,
+authentication keys, encryption keys, and other data in the kernel.
+.P
+System call interfaces are provided so that user-space programs can manage
+those objects and also use the facility for their own purposes; see
+.BR add_key (2),
+.BR request_key (2),
+and
+.BR keyctl (2).
+.P
+A library and some user-space utilities are provided to allow access to the
+facility.
+See
+.BR keyctl (1),
+.BR keyctl (3),
+and
+.BR keyutils (7)
+for more information.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Keys
+A key has the following attributes:
+.TP
+Serial number (ID)
+This is a unique integer handle by which a key is referred to in system calls.
+The serial number is sometimes synonymously referred as the key ID.
+Programmatically, key serial numbers are represented using the type
+.IR key_serial_t .
+.TP
+Type
+A key's type defines what sort of data can be held in the key,
+how the proposed content of the key will be parsed,
+and how the payload will be used.
+.IP
+There are a number of general-purpose types available, plus some specialist
+types defined by specific kernel components.
+.TP
+Description (name)
+The key description is a printable string that is used as the search term
+for the key (in conjunction with the key type) as well as a display name.
+During searches, the description may be partially matched or exactly matched.
+.TP
+Payload (data)
+The payload is the actual content of a key.
+This is usually set when a key is created,
+but it is possible for the kernel to upcall to user space to finish the
+instantiation of a key if that key wasn't already known to the kernel
+when it was requested.
+For further details, see
+.BR request_key (2).
+.IP
+A key's payload can be read and updated if the key type supports it and if
+suitable permission is granted to the caller.
+.TP
+Access rights
+Much as files do,
+each key has an owning user ID, an owning group ID, and a security label.
+Each key also has a set of permissions,
+though there are more than for a normal UNIX file,
+and there is an additional category\[em]possessor\[em]beyond the usual user,
+group, and other (see
+.IR Possession ,
+below).
+.IP
+Note that keys are quota controlled, since they require unswappable kernel
+memory.
+The owning user ID specifies whose quota is to be debited.
+.TP
+Expiration time
+Each key can have an expiration time set.
+When that time is reached,
+the key is marked as being expired and accesses to it fail with the error
+.BR EKEYEXPIRED .
+If not deleted, updated, or replaced, then, after a set amount of time,
+an expired key is automatically removed (garbage collected)
+along with all links to it,
+and attempts to access the key fail with the error
+.BR ENOKEY .
+.TP
+Reference count
+Each key has a reference count.
+Keys are referenced by keyrings, by currently active users,
+and by a process's credentials.
+When the reference count reaches zero,
+the key is scheduled for garbage collection.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Key types
+The kernel provides several basic types of key:
+.TP
+.I \[dq]keyring\[dq]
+.\" Note that keyrings use different fields in struct key in order to store
+.\" their data - index_key instead of type/description and name_link/keys
+.\" instead of payload.
+Keyrings are special keys which store a set of links
+to other keys (including other keyrings),
+analogous to a directory holding links to files.
+The main purpose of a keyring is to prevent other keys from
+being garbage collected because nothing refers to them.
+.IP
+Keyrings with descriptions (names)
+that begin with a period (\[aq].\[aq]) are reserved to the implementation.
+.TP
+.I \[dq]user\[dq]
+This is a general-purpose key type.
+The key is kept entirely within kernel memory.
+The payload may be read and updated by user-space applications.
+.IP
+The payload for keys of this type is a blob of arbitrary data
+of up to 32,767 bytes.
+.IP
+The description may be any valid string, though it is preferred that it
+start with a colon-delimited prefix representing the service
+to which the key is of interest
+(for instance
+.IR \[dq]afs:mykey\[dq] ).
+.TP
+.IR \[dq]logon\[dq] " (since Linux 3.3)"
+.\" commit 9f6ed2ca257fa8650b876377833e6f14e272848b
+This key type is essentially the same as
+.IR \[dq]user\[dq] ,
+but it does not provide reading (i.e., the
+.BR keyctl (2)
+.B KEYCTL_READ
+operation),
+meaning that the key payload is never visible from user space.
+This is suitable for storing username-password pairs
+that should not be readable from user space.
+.IP
+The description of a
+.I \[dq]logon\[dq]
+key
+.I must
+start with a non-empty colon-delimited prefix whose purpose
+is to identify the service to which the key belongs.
+(Note that this differs from keys of the
+.I \[dq]user\[dq]
+type, where the inclusion of a prefix is recommended but is not enforced.)
+.TP
+.IR \[dq]big_key\[dq] " (since Linux 3.13)"
+.\" commit ab3c3587f8cda9083209a61dbe3a4407d3cada10
+This key type is similar to the
+.I \[dq]user\[dq]
+key type, but it may hold a payload of up to 1\ MiB in size.
+This key type is useful for purposes such as holding Kerberos ticket caches.
+.IP
+The payload data may be stored in a tmpfs filesystem,
+rather than in kernel memory,
+if the data size exceeds the overhead of storing the data in the filesystem.
+(Storing the data in a filesystem requires filesystem structures
+to be allocated in the kernel.
+The size of these structures determines the size threshold
+above which the tmpfs storage method is used.)
+Since Linux 4.8,
+.\" commit 13100a72f40f5748a04017e0ab3df4cf27c809ef
+the payload data is encrypted when stored in tmpfs,
+thereby preventing it from being written unencrypted into swap space.
+.P
+There are more specialized key types available also,
+but they aren't discussed here
+because they aren't intended for normal user-space use.
+.P
+Key type names
+that begin with a period (\[aq].\[aq]) are reserved to the implementation.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Keyrings
+As previously mentioned, keyrings are a special type of key that contain
+links to other keys (which may include other keyrings).
+Keys may be linked to by multiple keyrings.
+Keyrings may be considered as analogous to UNIX directories
+where each directory contains a set of hard links to files.
+.P
+Various operations (system calls) may be applied only to keyrings:
+.TP
+Adding
+A key may be added to a keyring by system calls that create keys.
+This prevents the new key from being immediately deleted
+when the system call releases its last reference to the key.
+.TP
+Linking
+A link may be added to a keyring pointing to a key that is already known,
+provided this does not create a self-referential cycle.
+.TP
+Unlinking
+A link may be removed from a keyring.
+When the last link to a key is removed,
+that key will be scheduled for deletion by the garbage collector.
+.TP
+Clearing
+All the links may be removed from a keyring.
+.TP
+Searching
+A keyring may be considered the root of a tree or subtree in which keyrings
+form the branches and non-keyrings the leaves.
+This tree may be searched for a key matching
+a particular type and description.
+.P
+See
+.BR keyctl_clear (3),
+.BR keyctl_link (3),
+.BR keyctl_search (3),
+and
+.BR keyctl_unlink (3)
+for more information.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Anchoring keys
+To prevent a key from being garbage collected,
+it must be anchored to keep its reference count elevated
+when it is not in active use by the kernel.
+.P
+Keyrings are used to anchor other keys:
+each link is a reference on a key.
+Note that keyrings themselves are just keys and
+are also subject to the same anchoring requirement to prevent
+them being garbage collected.
+.P
+The kernel makes available a number of anchor keyrings.
+Note that some of these keyrings will be created only when first accessed.
+.TP
+Process keyrings
+Process credentials themselves reference keyrings with specific semantics.
+These keyrings are pinned as long as the set of credentials exists,
+which is usually as long as the process exists.
+.IP
+There are three keyrings with different inheritance/sharing rules:
+the
+.BR session\-keyring (7)
+(inherited and shared by all child processes),
+the
+.BR process\-keyring (7)
+(shared by all threads in a process) and
+the
+.BR thread\-keyring (7)
+(specific to a particular thread).
+.IP
+As an alternative to using the actual keyring IDs,
+in calls to
+.BR add_key (2),
+.BR keyctl (2),
+and
+.BR request_key (2),
+the special keyring values
+.BR KEY_SPEC_SESSION_KEYRING ,
+.BR KEY_SPEC_PROCESS_KEYRING ,
+and
+.B KEY_SPEC_THREAD_KEYRING
+can be used to refer to the caller's own instances of these keyrings.
+.TP
+User keyrings
+Each UID known to the kernel has a record that contains two keyrings: the
+.BR user\-keyring (7)
+and the
+.BR user\-session\-keyring (7).
+These exist for as long as the UID record in the kernel exists.
+.IP
+As an alternative to using the actual keyring IDs,
+in calls to
+.BR add_key (2),
+.BR keyctl (2),
+and
+.BR request_key (2),
+the special keyring values
+.B KEY_SPEC_USER_KEYRING
+and
+.B KEY_SPEC_USER_SESSION_KEYRING
+can be used to refer to the caller's own instances of these keyrings.
+.IP
+A link to the user keyring is placed in a new session keyring by
+.BR pam_keyinit (8)
+when a new login session is initiated.
+.TP
+Persistent keyrings
+There is a
+.BR persistent\-keyring (7)
+available to each UID known to the system.
+It may persist beyond the life of the UID record previously mentioned,
+but has an expiration time set such that it is automatically cleaned up
+after a set time.
+The persistent keyring permits, for example,
+.BR cron (8)
+scripts to use credentials that are left in the persistent keyring after
+the user logs out.
+.IP
+Note that the expiration time of the persistent keyring
+is reset every time the persistent key is requested.
+.TP
+Special keyrings
+There are special keyrings owned by the kernel that can anchor keys
+for special purposes.
+An example of this is the \fIsystem keyring\fR used for holding
+encryption keys for module signature verification.
+.IP
+These special keyrings  are usually closed to direct alteration
+by user space.
+.P
+An originally planned "group keyring",
+for storing keys associated with each GID known to the kernel,
+is not so far implemented, is unlikely to be implemented.
+Nevertheless, the constant
+.B KEY_SPEC_GROUP_KEYRING
+has been defined for this keyring.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Possession
+The concept of possession is important to understanding the keyrings
+security model.
+Whether a thread possesses a key is determined by the following rules:
+.IP (1) 5
+Any key or keyring that does not grant
+.I search
+permission to the caller is ignored in all the following rules.
+.IP (2)
+A thread possesses its
+.BR session\-keyring (7),
+.BR process\-keyring (7),
+and
+.BR thread\-keyring (7)
+directly because those keyrings are referred to by its credentials.
+.IP (3)
+If a keyring is possessed, then any key it links to is also possessed.
+.IP (4)
+If any key a keyring links to is itself a keyring, then rule (3) applies
+recursively.
+.IP (5)
+If a process is upcalled from the kernel to instantiate a key (see
+.BR request_key (2)),
+then it also possesses the requester's keyrings as in
+rule (1) as if it were the requester.
+.P
+Note that possession is not a fundamental property of a key,
+but must rather be calculated each time the key is needed.
+.P
+Possession is designed to allow set-user-ID programs run from, say
+a user's shell to access the user's keys.
+Granting permissions to the key possessor while denying them
+to the key owner and group allows the prevention of access to keys
+on the basis of UID and GID matches.
+.P
+When it creates the session keyring,
+.BR pam_keyinit (8)
+adds a link to the
+.BR user\-keyring (7),
+thus making the user keyring and anything it contains possessed by default.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Access rights
+Each key has the following security-related attributes:
+.IP \[bu] 3
+The owning user ID
+.IP \[bu]
+The ID of a group that is permitted to access the key
+.IP \[bu]
+A security label
+.IP \[bu]
+A permissions mask
+.P
+The permissions mask contains four sets of rights.
+The first three sets are mutually exclusive.
+One and only one will be in force for a particular access check.
+In order of descending priority, these three sets are:
+.TP
+.I user
+The set specifies the rights granted
+if the key's user ID matches the caller's filesystem user ID.
+.TP
+.I group
+The set specifies the rights granted
+if the user ID didn't match and the key's group ID matches the caller's
+filesystem GID or one of the caller's supplementary group IDs.
+.TP
+.I other
+The set specifies the rights granted
+if neither the key's user ID nor group ID matched.
+.P
+The fourth set of rights is:
+.TP
+.I possessor
+The set specifies the rights granted
+if a key is determined to be possessed by the caller.
+.P
+The complete set of rights for a key is the union of whichever
+of the first three sets is applicable plus the fourth set
+if the key is possessed.
+.P
+The set of rights that may be granted in each of the four masks
+is as follows:
+.TP
+.I view
+The attributes of the key may be read.
+This includes the type,
+description, and access rights (excluding the security label).
+.TP
+.I read
+For a key: the payload of the key may be read.
+For a keyring: the list of serial numbers (keys) to
+which the keyring has links may be read.
+.TP
+.I write
+The payload of the key may be updated and the key may be revoked.
+For a keyring, links may be added to or removed from the keyring,
+and the keyring may be cleared completely (all links are removed),
+.TP
+.I search
+For a key (or a keyring): the key may be found by a search.
+For a keyring: keys and keyrings that are linked to by the
+keyring may be searched.
+.TP
+.I link
+Links may be created from keyrings to the key.
+The initial link to a key that is established when the key is created
+doesn't require this permission.
+.TP
+.I setattr
+The ownership details and security label of the key may be changed,
+the key's expiration time may be set, and the key may be revoked.
+.P
+In addition to access rights, any active Linux Security Module (LSM) may
+prevent access to a key if its policy so dictates.
+A key may be given a
+security label or other attribute by the LSM;
+this label is retrievable via
+.BR keyctl_get_security (3).
+.P
+See
+.BR keyctl_chown (3),
+.BR keyctl_describe (3),
+.BR keyctl_get_security (3),
+.BR keyctl_setperm (3),
+and
+.BR selinux (8)
+for more information.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Searching for keys
+One of the key features of the Linux key-management facility
+is the ability to find a key that a process is retaining.
+The
+.BR request_key (2)
+system call is the primary point of
+access for user-space applications to find a key.
+(Internally, the kernel has something similar available
+for use by internal components that make use of keys.)
+.P
+The search algorithm works as follows:
+.IP (1) 5
+The process keyrings are searched in the following order: the
+.BR thread\-keyring (7)
+if it exists, the
+.BR process\-keyring (7)
+if it exists, and then either the
+.BR session\-keyring (7)
+if it exists or the
+.BR user\-session\-keyring (7)
+if that exists.
+.IP (2)
+If the caller was a process that was invoked by the
+.BR request_key (2)
+upcall mechanism, then the keyrings of the original caller of
+.BR request_key (2)
+will be searched as well.
+.IP (3)
+The search of a keyring tree is in breadth-first order:
+each keyring is searched first for a match,
+then the keyrings referred to by that keyring are searched.
+.IP (4)
+If a matching key is found that is valid,
+then the search terminates and that key is returned.
+.IP (5)
+If a matching key is found that has an error state attached,
+that error state is noted and the search continues.
+.IP (6)
+If no valid matching key is found,
+then the first noted error state is returned; otherwise, an
+.B ENOKEY
+error is returned.
+.P
+It is also possible to search a specific keyring, in which case only steps
+(3) to (6) apply.
+.P
+See
+.BR request_key (2)
+and
+.BR keyctl_search (3)
+for more information.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS On-demand key creation
+If a key cannot be found,
+.BR request_key (2)
+will, if given a
+.I callout_info
+argument, create a new key and then upcall to user space to
+instantiate the key.
+This allows keys to be created on an as-needed basis.
+.P
+Typically,
+this will involve the kernel creating a new process that executes the
+.BR request\-key (8)
+program, which will then execute the appropriate handler based on its
+configuration.
+.P
+The handler is passed a special authorization key that allows it
+and only it to instantiate the new key.
+This is also used to permit searches performed by the
+handler program to also search the requester's keyrings.
+.P
+See
+.BR request_key (2),
+.BR keyctl_assume_authority (3),
+.BR keyctl_instantiate (3),
+.BR keyctl_negate (3),
+.BR keyctl_reject (3),
+.BR request\-key (8),
+and
+.BR request\-key.conf (5)
+for more information.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS /proc files
+The kernel provides various
+.I /proc
+files that expose information about keys or define limits on key usage.
+.TP
+.IR /proc/keys " (since Linux 2.6.10)"
+This file exposes a list of the keys for which the reading thread has
+.I view
+permission, providing various information about each key.
+The thread need not possess the key for it to be visible in this file.
+.\" David Howells, Dec 2016 linux-man@:
+.\" This [The thread need not possess the key for it to be visible in
+.\" this file.] is correct.  See proc_keys_show() in security/keys/proc.c:
+.\"
+.\"	rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
+.\"	if (rc < 0)
+.\"		return 0;
+.\"
+.\"Possibly it shouldn't be, but for now it is.
+.\"
+.IP
+The only keys included in the list are those that grant
+.I view
+permission to the reading process
+(regardless of whether or not it possesses them).
+LSM security checks are still performed,
+and may filter out further keys that the process is not authorized to view.
+.IP
+An example of the data that one might see in this file
+(with the columns numbered for easy reference below)
+is the following:
+.IP
+.EX
+  (1)     (2)     (3)(4)    (5)     (6)   (7)   (8)        (9)
+009a2028 I\-\-Q\-\-\-   1 perm 3f010000  1000  1000 user     krb_ccache:primary: 12
+1806c4ba I\-\-Q\-\-\-   1 perm 3f010000  1000  1000 keyring  _pid: 2
+25d3a08f I\-\-Q\-\-\-   1 perm 1f3f0000  1000 65534 keyring  _uid_ses.1000: 1
+28576bd8 I\-\-Q\-\-\-   3 perm 3f010000  1000  1000 keyring  _krb: 1
+2c546d21 I\-\-Q\-\-\- 190 perm 3f030000  1000  1000 keyring  _ses: 2
+30a4e0be I\-\-\-\-\-\-   4   2d 1f030000  1000 65534 keyring  _persistent.1000: 1
+32100fab I\-\-Q\-\-\-   4 perm 1f3f0000  1000 65534 keyring  _uid.1000: 2
+32a387ea I\-\-Q\-\-\-   1 perm 3f010000  1000  1000 keyring  _pid: 2
+3ce56aea I\-\-Q\-\-\-   5 perm 3f030000  1000  1000 keyring  _ses: 1
+.EE
+.IP
+The fields shown in each line of this file are as follows:
+.RS
+.TP
+ID (1)
+The ID (serial number) of the key, expressed in hexadecimal.
+.TP
+Flags (2)
+A set of flags describing the state of the key:
+.RS
+.TP
+I
+.\" KEY_FLAG_INSTANTIATED
+The key has been instantiated.
+.TP
+R
+.\" KEY_FLAG_REVOKED
+The key has been revoked.
+.TP
+D
+.\" KEY_FLAG_DEAD
+The key is dead (i.e., the key type has been unregistered).
+.\" unregister_key_type() in the kernel source
+(A key may be briefly in this state during garbage collection.)
+.TP
+Q
+.\" KEY_FLAG_IN_QUOTA
+The key contributes to the user's quota.
+.TP
+U
+.\" KEY_FLAG_USER_CONSTRUCT
+The key is under construction via a callback to user space;
+see
+.BR request\-key (2).
+.TP
+N
+.\" KEY_FLAG_NEGATIVE
+The key is negatively instantiated.
+.TP
+i
+.\" KEY_FLAG_INVALIDATED
+The key has been invalidated.
+.RE
+.TP
+Usage (3)
+This is a count of the number of kernel credential
+structures that are pinning the key
+(approximately: the number of threads and open file references
+that refer to this key).
+.TP
+Timeout (4)
+The amount of time until the key will expire,
+expressed in human-readable form (weeks, days, hours, minutes, and seconds).
+The string
+.I perm
+here means that the key is permanent (no timeout).
+The string
+.I expd
+means that the key has already expired,
+but has not yet been garbage collected.
+.TP
+Permissions (5)
+The key permissions, expressed as four hexadecimal bytes containing,
+from left to right, the possessor, user, group, and other permissions.
+Within each byte, the permission bits are as follows:
+.IP
+.PD 0
+.RS 12
+.TP
+0x01
+.I view
+.TP
+0x02
+.I read
+.TP
+0x04
+.I write
+.TP
+0x08
+.I search
+.TP
+0x10
+.I link
+.TP
+0x20
+.I setattr
+.RE
+.PD
+.TP
+UID (6)
+The user ID of the key owner.
+.TP
+GID (7)
+The group ID of the key.
+The value \-1 here means that the key has no group ID;
+this can occur in certain circumstances for keys created by the kernel.
+.TP
+Type (8)
+The key type (user, keyring, etc.)
+.TP
+Description (9)
+The key description (name).
+This field contains descriptive information about the key.
+For most key types, it has the form
+.IP
+.in +4n
+.EX
+name[: extra\-info]
+.EE
+.in
+.IP
+The
+.I name
+subfield is the key's description (name).
+The optional
+.I extra\-info
+field provides some further information about the key.
+The information that appears here depends on the key type, as follows:
+.RS
+.TP
+.IR \[dq]user\[dq] " and " \[dq]logon\[dq]
+The size in bytes of the key payload (expressed in decimal).
+.TP
+.I \[dq]keyring\[dq]
+The number of keys linked to the keyring,
+or the string
+.I empty
+if there are no keys linked to the keyring.
+.TP
+.I \[dq]big_key\[dq]
+The payload size in bytes, followed either by the string
+.IR [file] ,
+if the key payload exceeds the threshold that means that the
+payload is stored in a (swappable)
+.BR tmpfs (5)
+filesystem,
+or otherwise the string
+.IR [buff] ,
+indicating that the key is small enough to reside in kernel memory.
+.RE
+.IP
+For the
+.I \[dq].request_key_auth\[dq]
+key type
+(authorization key; see
+.BR request_key (2)),
+the description field has the form shown in the following example:
+.IP
+.in +4n
+.EX
+key:c9a9b19 pid:28880 ci:10
+.EE
+.in
+.IP
+The three subfields are as follows:
+.RS
+.TP
+.I key
+The hexadecimal ID of the key being instantiated in the requesting program.
+.TP
+.I pid
+The PID of the requesting program.
+.TP
+.I ci
+The length of the callout data with which the requested key should
+be instantiated
+(i.e., the length of the payload associated with the authorization key).
+.RE
+.RE
+.TP
+.IR /proc/key\-users " (since Linux 2.6.10)"
+This file lists various information for each user ID that
+has at least one key on the system.
+An example of the data that one might see in this file is the following:
+.IP
+.in +4n
+.EX
+   0:    10 9/9 2/1000000 22/25000000
+  42:     9 9/9 8/200 106/20000
+1000:    11 11/11 10/200 271/20000
+.EE
+.in
+.IP
+The fields shown in each line are as follows:
+.RS
+.TP
+.I uid
+The user ID.
+.TP
+.I usage
+This is a kernel-internal usage count for the kernel structure
+used to record key users.
+.TP
+.IR nkeys / nikeys
+The total number of keys owned by the user,
+and the number of those keys that have been instantiated.
+.TP
+.IR qnkeys / maxkeys
+The number of keys owned by the user,
+and the maximum number of keys that the user may own.
+.TP
+.IR qnbytes / maxbytes
+The number of bytes consumed in payloads of the keys owned by this user,
+and the upper limit on the number of bytes in key payloads for that user.
+.RE
+.TP
+.IR /proc/sys/kernel/keys/gc_delay " (since Linux 2.6.32)"
+.\" commit 5d135440faf7db8d566de0c6fab36b16cf9cfc3b
+The value in this file specifies the interval, in seconds,
+after which revoked and expired keys will be garbage collected.
+The purpose of having such an interval is so that there is a window
+of time where user space can see an error (respectively
+.B EKEYREVOKED
+and
+.BR EKEYEXPIRED )
+that indicates what happened to the key.
+.IP
+The default value in this file is 300 (i.e., 5 minutes).
+.TP
+.IR /proc/sys/kernel/keys/persistent_keyring_expiry " (since Linux 3.13)"
+.\" commit f36f8c75ae2e7d4da34f4c908cebdb4aa42c977e
+This file defines an interval, in seconds,
+to which the persistent keyring's expiration timer is reset
+each time the keyring is accessed (via
+.BR keyctl_get_persistent (3)
+or the
+.BR keyctl (2)
+.B KEYCTL_GET_PERSISTENT
+operation.)
+.IP
+The default value in this file is 259200 (i.e., 3 days).
+.P
+The following files (which are writable by privileged processes)
+are used to enforce quotas on the number of keys
+and number of bytes of data that can be stored in key payloads:
+.TP
+.IR /proc/sys/kernel/keys/maxbytes " (since Linux 2.6.26)"
+.\" commit 0b77f5bfb45c13e1e5142374f9d6ca75292252a4
+.\" Previously: KEYQUOTA_MAX_BYTES      10000
+This is the maximum number of bytes of data that a nonroot user
+can hold in the payloads of the keys owned by the user.
+.IP
+The default value in this file is 20,000.
+.TP
+.IR /proc/sys/kernel/keys/maxkeys " (since Linux 2.6.26)"
+.\" commit 0b77f5bfb45c13e1e5142374f9d6ca75292252a4
+.\" Previously: KEYQUOTA_MAX_KEYS       100
+This is the maximum number of keys that a nonroot user may own.
+.IP
+The default value in this file is 200.
+.TP
+.IR /proc/sys/kernel/keys/root_maxbytes " (since Linux 2.6.26)"
+This is the maximum number of bytes of data that the root user
+(UID 0 in the root user namespace)
+can hold in the payloads of the keys owned by root.
+.IP
+.\"738c5d190f6540539a04baf36ce21d46b5da04bd
+The default value in this file is 25,000,000 (20,000 before Linux 3.17).
+.\" commit 0b77f5bfb45c13e1e5142374f9d6ca75292252a4
+.TP
+.IR /proc/sys/kernel/keys/root_maxkeys " (since Linux 2.6.26)"
+.\" commit 0b77f5bfb45c13e1e5142374f9d6ca75292252a4
+This is the maximum number of keys that the root user
+(UID 0 in the root user namespace)
+may own.
+.IP
+.\"738c5d190f6540539a04baf36ce21d46b5da04bd
+The default value in this file is 1,000,000 (200 before Linux 3.17).
+.P
+With respect to keyrings,
+note that each link in a keyring consumes 4 bytes of the keyring payload.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SS Users
+The Linux key-management facility has a number of users and usages,
+but is not limited to those that already exist.
+.P
+In-kernel users of this facility include:
+.TP
+Network filesystems - DNS
+The kernel uses the upcall mechanism provided by the keys to upcall to
+user space to do DNS lookups and then to cache the results.
+.TP
+AF_RXRPC and kAFS - Authentication
+The AF_RXRPC network protocol and the in-kernel AFS filesystem
+use keys to store the ticket needed to do secured or encrypted traffic.
+These are then looked up by
+network operations on AF_RXRPC and filesystem operations on kAFS.
+.TP
+NFS - User ID mapping
+The NFS filesystem uses keys to store mappings of
+foreign user IDs to local user IDs.
+.TP
+CIFS - Password
+The CIFS filesystem uses keys to store passwords for accessing remote shares.
+.TP
+Module verification
+The kernel build process can be made to cryptographically sign modules.
+That signature is then checked when a module is loaded.
+.P
+User-space users of this facility include:
+.TP
+Kerberos key storage
+The MIT Kerberos 5 facility (libkrb5) can use keys to store authentication
+tokens which can be made to be automatically cleaned up a set time after
+the user last uses them,
+but until then permits them to hang around after the user
+has logged out so that
+.BR cron (8)
+scripts can use them.
+.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR add_key (2),
+.BR keyctl (2),
+.BR request_key (2),
+.BR keyctl (3),
+.BR keyutils (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7),
+.BR user\-session\-keyring (7),
+.BR pam_keyinit (8),
+.BR request\-key (8)
+.P
+The kernel source files
+.I Documentation/crypto/asymmetric\-keys.txt
+and under
+.I Documentation/security/keys
+(or, before Linux 4.13, in the file
+.IR Documentation/security/keys.txt ).
diff --git a/man/man7/koi8-r.7 b/man/man7/koi8-r.7
new file mode 100644
index 000000000..3e1826a90
--- /dev/null
+++ b/man/man7/koi8-r.7
@@ -0,0 +1,169 @@
+'\" t
+.\" Copyright 2001      Alexey Mahotkin <alexm@hsys.msk.ru>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH KOI8-R 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+koi8-r \- Russian character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+RFC\ 1489 defines an 8-bit character set, KOI8-R.
+KOI8-R encodes the
+characters used in Russian.
+.SS KOI8-R characters
+The following table displays the characters in KOI8-R that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+200	128	80	─	BOX DRAWINGS LIGHT HORIZONTAL
+201	129	81	│	BOX DRAWINGS LIGHT VERTICAL
+202	130	82	┌	BOX DRAWINGS LIGHT DOWN AND RIGHT
+203	131	83	┐	BOX DRAWINGS LIGHT DOWN AND LEFT
+204	132	84	└	BOX DRAWINGS LIGHT UP AND RIGHT
+205	133	85	┘	BOX DRAWINGS LIGHT UP AND LEFT
+206	134	86	├	BOX DRAWINGS LIGHT VERTICAL AND RIGHT
+207	135	87	┤	BOX DRAWINGS LIGHT VERTICAL AND LEFT
+210	136	88	┬	BOX DRAWINGS LIGHT DOWN AND HORIZONTAL
+211	137	89	┴	BOX DRAWINGS LIGHT UP AND HORIZONTAL
+212	138	8A	┼	BOX DRAWINGS LIGHT VERTICAL AND HORIZONTAL
+213	139	8B	▀	UPPER HALF BLOCK
+214	140	8C	▄	LOWER HALF BLOCK
+215	141	8D	█	FULL BLOCK
+216	142	8E	▌	LEFT HALF BLOCK
+217	143	8F	▐	RIGHT HALF BLOCK
+220	144	90	░	LIGHT SHADE
+221	145	91	▒	MEDIUM SHADE
+222	146	92	▓	DARK SHADE
+223	147	93	⌠	TOP HALF INTEGRAL
+224	148	94	■	BLACK SQUARE
+225	149	95	∙	BULLET OPERATOR
+226	150	96	√	SQUARE ROOT
+227	151	97	≈	ALMOST EQUAL TO
+230	152	98	≤	LESS-THAN OR EQUAL TO
+231	153	99	≥	GREATER-THAN OR EQUAL TO
+232	154	9A	 	NO-BREAK SPACE
+233	155	9B	⌡	BOTTOM HALF INTEGRAL
+234	156	9C	°	DEGREE SIGN
+235	157	9D	²	SUPERSCRIPT TWO
+236	158	9E	·	MIDDLE DOT
+237	159	9F	÷	DIVISION SIGN
+240	160	A0	═	BOX DRAWINGS DOUBLE HORIZONTAL
+241	161	A1	║	BOX DRAWINGS DOUBLE VERTICAL
+242	162	A2	╒	BOX DRAWINGS DOWN SINGLE AND RIGHT DOUBLE
+243	163	A3	ё	CYRILLIC SMALL LETTER IO
+244	164	A4	╓	BOX DRAWINGS DOWN DOUBLE AND RIGHT SINGLE
+245	165	A5	╔	BOX DRAWINGS DOUBLE DOWN AND RIGHT
+246	166	A6	╕	BOX DRAWINGS DOWN SINGLE AND LEFT DOUBLE
+247	167	A7	╖	BOX DRAWINGS DOWN DOUBLE AND LEFT SINGLE
+250	168	A8	╗	BOX DRAWINGS DOUBLE DOWN AND LEFT
+251	169	A9	╘	BOX DRAWINGS UP SINGLE AND RIGHT DOUBLE
+252	170	AA	╙	BOX DRAWINGS UP DOUBLE AND RIGHT SINGLE
+253	171	AB	╚	BOX DRAWINGS DOUBLE UP AND RIGHT
+254	172	AC	╛	BOX DRAWINGS UP SINGLE AND LEFT DOUBLE
+255	173	AD	╜	BOX DRAWINGS UP DOUBLE AND LEFT SINGLE
+256	174	AE	╝	BOX DRAWINGS DOUBLE UP AND LEFT
+257	175	AF	╞	BOX DRAWINGS VERTICAL SINGLE AND RIGHT DOUBLE
+260	176	B0	╟	BOX DRAWINGS VERTICAL DOUBLE AND RIGHT SINGLE
+261	177	B1	╠	BOX DRAWINGS DOUBLE VERTICAL AND RIGHT
+262	178	B2	╡	BOX DRAWINGS VERTICAL SINGLE AND LEFT DOUBLE
+263	179	B3	Ё	CYRILLIC CAPITAL LETTER IO
+264	180	B4	╢	BOX DRAWINGS VERTICAL DOUBLE AND LEFT SINGLE
+265	181	B5	╣	BOX DRAWINGS DOUBLE VERTICAL AND LEFT
+266	182	B6	╤	BOX DRAWINGS DOWN SINGLE AND HORIZONTAL DOUBLE
+267	183	B7	╥	BOX DRAWINGS DOWN DOUBLE AND HORIZONTAL SINGLE
+270	184	B8	╦	BOX DRAWINGS DOUBLE DOWN AND HORIZONTAL
+271	185	B9	╧	BOX DRAWINGS UP SINGLE AND HORIZONTAL DOUBLE
+272	186	BA	╨	BOX DRAWINGS UP DOUBLE AND HORIZONTAL SINGLE
+273	187	BB	╩	BOX DRAWINGS DOUBLE UP AND HORIZONTAL
+274	188	BC	╪	T{
+BOX DRAWINGS VERTICAL SINGLE
+.br
+AND HORIZONTAL DOUBLE
+T}
+275	189	BD	╫	T{
+BOX DRAWINGS VERTICAL DOUBLE
+.br
+AND HORIZONTAL SINGLE
+T}
+276	190	BE	╬	BOX DRAWINGS DOUBLE VERTICAL AND HORIZONTAL
+277	191	BF	©	COPYRIGHT SIGN
+300	192	C0	ю	CYRILLIC SMALL LETTER YU
+301	193	C1	а	CYRILLIC SMALL LETTER A
+302	194	C2	б	CYRILLIC SMALL LETTER BE
+303	195	C3	ц	CYRILLIC SMALL LETTER TSE
+304	196	C4	д	CYRILLIC SMALL LETTER DE
+305	197	C5	е	CYRILLIC SMALL LETTER IE
+306	198	C6	ф	CYRILLIC SMALL LETTER EF
+307	199	C7	г	CYRILLIC SMALL LETTER GHE
+310	200	C8	х	CYRILLIC SMALL LETTER HA
+311	201	C9	и	CYRILLIC SMALL LETTER I
+312	202	CA	й	CYRILLIC SMALL LETTER SHORT I
+313	203	CB	к	CYRILLIC SMALL LETTER KA
+314	204	CC	л	CYRILLIC SMALL LETTER EL
+315	205	CD	м	CYRILLIC SMALL LETTER EM
+316	206	CE	н	CYRILLIC SMALL LETTER EN
+317	207	CF	о	CYRILLIC SMALL LETTER O
+320	208	D0	п	CYRILLIC SMALL LETTER PE
+321	209	D1	я	CYRILLIC SMALL LETTER YA
+322	210	D2	р	CYRILLIC SMALL LETTER ER
+323	211	D3	с	CYRILLIC SMALL LETTER ES
+324	212	D4	т	CYRILLIC SMALL LETTER TE
+325	213	D5	у	CYRILLIC SMALL LETTER U
+326	214	D6	ж	CYRILLIC SMALL LETTER ZHE
+327	215	D7	в	CYRILLIC SMALL LETTER VE
+330	216	D8	ь	CYRILLIC SMALL LETTER SOFT SIGN
+331	217	D9	ы	CYRILLIC SMALL LETTER YERU
+332	218	DA	з	CYRILLIC SMALL LETTER ZE
+333	219	DB	ш	CYRILLIC SMALL LETTER SHA
+334	220	DC	э	CYRILLIC SMALL LETTER E
+335	221	DD	щ	CYRILLIC SMALL LETTER SHCHA
+336	222	DE	ч	CYRILLIC SMALL LETTER CHE
+337	223	DF	ъ	CYRILLIC SMALL LETTER HARD SIGN
+340	224	E0	Ю	CYRILLIC CAPITAL LETTER YU
+341	225	E1	А	CYRILLIC CAPITAL LETTER A
+342	226	E2	Б	CYRILLIC CAPITAL LETTER BE
+343	227	E3	Ц	CYRILLIC CAPITAL LETTER TSE
+344	228	E4	Д	CYRILLIC CAPITAL LETTER DE
+345	229	E5	Е	CYRILLIC CAPITAL LETTER IE
+346	230	E6	Ф	CYRILLIC CAPITAL LETTER EF
+347	231	E7	Г	CYRILLIC CAPITAL LETTER GHE
+350	232	E8	Х	CYRILLIC CAPITAL LETTER HA
+351	233	E9	И	CYRILLIC CAPITAL LETTER I
+352	234	EA	Й	CYRILLIC CAPITAL LETTER SHORT I
+353	235	EB	К	CYRILLIC CAPITAL LETTER KA
+354	236	EC	Л	CYRILLIC CAPITAL LETTER EL
+355	237	ED	М	CYRILLIC CAPITAL LETTER EM
+356	238	EE	Н	CYRILLIC CAPITAL LETTER EN
+357	239	EF	О	CYRILLIC CAPITAL LETTER O
+360	240	F0	П	CYRILLIC CAPITAL LETTER PE
+361	241	F1	Я	CYRILLIC CAPITAL LETTER YA
+362	242	F2	Р	CYRILLIC CAPITAL LETTER ER
+363	243	F3	С	CYRILLIC CAPITAL LETTER ES
+364	244	F4	Т	CYRILLIC CAPITAL LETTER TE
+365	245	F5	У	CYRILLIC CAPITAL LETTER U
+366	246	F6	Ж	CYRILLIC CAPITAL LETTER ZHE
+367	247	F7	В	CYRILLIC CAPITAL LETTER VE
+370	248	F8	Ь	CYRILLIC CAPITAL LETTER SOFT SIGN
+371	249	F9	Ы	CYRILLIC CAPITAL LETTER YERU
+372	250	FA	З	CYRILLIC CAPITAL LETTER ZE
+373	251	FB	Ш	CYRILLIC CAPITAL LETTER SHA
+374	252	FC	Э	CYRILLIC CAPITAL LETTER E
+375	253	FD	Щ	CYRILLIC CAPITAL LETTER SHCHA
+376	254	FE	Ч	CYRILLIC CAPITAL LETTER CHE
+377	255	FF	Ъ	CYRILLIC CAPITAL LETTER HARD SIGN
+.TE
+.SH NOTES
+The differences with KOI8-U are in the hex positions
+A4, A6, A7, AD, B4, B6, B7, and BD.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR cp1251 (7),
+.BR iso_8859\-5 (7),
+.BR koi8\-u (7),
+.BR utf\-8 (7)
diff --git a/man/man7/koi8-u.7 b/man/man7/koi8-u.7
new file mode 100644
index 000000000..28cd1a4f1
--- /dev/null
+++ b/man/man7/koi8-u.7
@@ -0,0 +1,175 @@
+'\" t
+.\" Copyright 2009  Lefteris Dimitroulakis <edimitro at tee.gr>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2009-01-15, mtk, Some edits
+.\"
+.TH KOI8-U 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+koi8-u \- Ukrainian character set encoded in octal, decimal,
+and hexadecimal
+.SH DESCRIPTION
+RFC\ 2310 defines an 8-bit character set, KOI8-U.
+KOI8-U encodes the
+characters used in Ukrainian and Byelorussian.
+.SS KOI8-U characters
+The following table displays the characters in KOI8-U that
+are printable and unlisted in the
+.BR ascii (7)
+manual page.
+.TS
+l l l c lp-1.
+Oct	Dec	Hex	Char	Description
+_
+200	128	80	─	BOX DRAWINGS LIGHT HORIZONTAL
+201	129	81	│	BOX DRAWINGS LIGHT VERTICAL
+202	130	82	┌	BOX DRAWINGS LIGHT DOWN AND RIGHT
+203	131	83	┐	BOX DRAWINGS LIGHT DOWN AND LEFT
+204	132	84	└	BOX DRAWINGS LIGHT UP AND RIGHT
+205	133	85	┘	BOX DRAWINGS LIGHT UP AND LEFT
+206	134	86	├	BOX DRAWINGS LIGHT VERTICAL AND RIGHT
+207	135	87	┤	BOX DRAWINGS LIGHT VERTICAL AND LEFT
+210	136	88	┬	BOX DRAWINGS LIGHT DOWN AND HORIZONTAL
+211	137	89	┴	BOX DRAWINGS LIGHT UP AND HORIZONTAL
+212	138	8A	┼	BOX DRAWINGS LIGHT VERTICAL AND HORIZONTAL
+213	139	8B	▀	UPPER HALF BLOCK
+214	140	8C	▄	LOWER HALF BLOCK
+215	141	8D	█	FULL BLOCK
+216	142	8E	▌	LEFT HALF BLOCK
+217	143	8F	▐	RIGHT HALF BLOCK
+220	144	90	░	LIGHT SHADE
+221	145	91	▒	MEDIUM SHADE
+222	146	92	▓	DARK SHADE
+223	147	93	⌠	TOP HALF INTEGRAL
+224	148	94	■	BLACK SQUARE
+225	149	95	∙	BULLET OPERATOR
+226	150	96	√	SQUARE ROOT
+227	151	97	≈	ALMOST EQUAL TO
+230	152	98	≤	LESS-THAN OR EQUAL TO
+231	153	99	≥	GREATER-THAN OR EQUAL TO
+232	154	9A	 	NO-BREAK SPACE
+233	155	9B	⌡	BOTTOM HALF INTEGRAL
+234	156	9C	°	DEGREE SIGN
+235	157	9D	²	SUPERSCRIPT TWO
+236	158	9E	·	MIDDLE DOT
+237	159	9F	÷	DIVISION SIGN
+240	160	A0	═	BOX DRAWINGS DOUBLE HORIZONTAL
+241	161	A1	║	BOX DRAWINGS DOUBLE VERTICAL
+242	162	A2	╒	BOX DRAWINGS DOWN SINGLE AND RIGHT DOUBLE
+243	163	A3	ё	CYRILLIC SMALL LETTER IO
+244	164	A4	є	CYRILLIC SMALL LETTER UKRAINIAN IE
+245	165	A5	╔	BOX DRAWINGS DOUBLE DOWN AND RIGHT
+246	166	A6	і	T{
+CYRILLIC SMALL LETTER
+.br
+BYELORUSSIAN-UKRAINIAN I
+T}
+247	167	A7	ї	CYRILLIC SMALL LETTER YI (Ukrainian)
+250	168	A8	╗	BOX DRAWINGS DOUBLE DOWN AND LEFT
+251	169	A9	╘	BOX DRAWINGS UP SINGLE AND RIGHT DOUBLE
+252	170	AA	╙	BOX DRAWINGS UP DOUBLE AND RIGHT SINGLE
+253	171	AB	╚	BOX DRAWINGS DOUBLE UP AND RIGHT
+254	172	AC	╛	BOX DRAWINGS UP SINGLE AND LEFT DOUBLE
+255	173	AD	ґ	CYRILLIC SMALL LETTER GHE WITH UPTURN
+256	174	AE	╝	BOX DRAWINGS DOUBLE UP AND LEFT
+257	175	AF	╞	BOX DRAWINGS VERTICAL SINGLE AND RIGHT DOUBLE
+260	176	B0	╟	BOX DRAWINGS VERTICAL DOUBLE AND RIGHT SINGLE
+261	177	B1	╠	BOX DRAWINGS DOUBLE VERTICAL AND RIGHT
+262	178	B2	╡	BOX DRAWINGS VERTICAL SINGLE AND LEFT DOUBLE
+263	179	B3	Ё	CYRILLIC CAPITAL LETTER IO
+264	180	B4	Є	CYRILLIC CAPITAL LETTER UKRAINIAN IE
+265	181	B5	╣	BOX DRAWINGS DOUBLE VERTICAL AND LEFT
+266	182	B6	І	T{
+CYRILLIC CAPITAL LETTER
+.br
+BYELORUSSIAN-UKRAINIAN I
+T}
+267	183	B7	Ї	CYRILLIC CAPITAL LETTER YI (Ukrainian)
+270	184	B8	╦	BOX DRAWINGS DOUBLE DOWN AND HORIZONTAL
+271	185	B9	╧	BOX DRAWINGS UP SINGLE AND HORIZONTAL DOUBLE
+272	186	BA	╨	BOX DRAWINGS UP DOUBLE AND HORIZONTAL SINGLE
+273	187	BB	╩	BOX DRAWINGS DOUBLE UP AND HORIZONTAL
+274	188	BC	╪	T{
+BOX DRAWINGS VERTICAL SINGLE
+.br
+AND HORIZONTAL DOUBLE
+T}
+275	189	BD	Ґ	CYRILLIC CAPITAL LETTER GHE WITH UPTURN
+276	190	BE	╬	BOX DRAWINGS DOUBLE VERTICAL AND HORIZONTAL
+277	191	BF	©	COPYRIGHT SIGN
+300	192	C0	ю	CYRILLIC SMALL LETTER YU
+301	193	C1	а	CYRILLIC SMALL LETTER A
+302	194	C2	б	CYRILLIC SMALL LETTER BE
+303	195	C3	ц	CYRILLIC SMALL LETTER TSE
+304	196	C4	д	CYRILLIC SMALL LETTER DE
+305	197	C5	е	CYRILLIC SMALL LETTER IE
+306	198	C6	ф	CYRILLIC SMALL LETTER EF
+307	199	C7	г	CYRILLIC SMALL LETTER GHE
+310	200	C8	х	CYRILLIC SMALL LETTER HA
+311	201	C9	и	CYRILLIC SMALL LETTER I
+312	202	CA	й	CYRILLIC SMALL LETTER SHORT I
+313	203	CB	к	CYRILLIC SMALL LETTER KA
+314	204	CC	л	CYRILLIC SMALL LETTER EL
+315	205	CD	м	CYRILLIC SMALL LETTER EM
+316	206	CE	н	CYRILLIC SMALL LETTER EN
+317	207	CF	о	CYRILLIC SMALL LETTER O
+320	208	D0	п	CYRILLIC SMALL LETTER PE
+321	209	D1	я	CYRILLIC SMALL LETTER YA
+322	210	D2	р	CYRILLIC SMALL LETTER ER
+323	211	D3	с	CYRILLIC SMALL LETTER ES
+324	212	D4	т	CYRILLIC SMALL LETTER TE
+325	213	D5	у	CYRILLIC SMALL LETTER U
+326	214	D6	ж	CYRILLIC SMALL LETTER ZHE
+327	215	D7	в	CYRILLIC SMALL LETTER VE
+330	216	D8	ь	CYRILLIC SMALL LETTER SOFT SIGN
+331	217	D9	ы	CYRILLIC SMALL LETTER YERU
+332	218	DA	з	CYRILLIC SMALL LETTER ZE
+333	219	DB	ш	CYRILLIC SMALL LETTER SHA
+334	220	DC	э	CYRILLIC SMALL LETTER E
+335	221	DD	щ	CYRILLIC SMALL LETTER SHCHA
+336	222	DE	ч	CYRILLIC SMALL LETTER CHE
+337	223	DF	ъ	CYRILLIC SMALL LETTER HARD SIGN
+340	224	E0	Ю	CYRILLIC CAPITAL LETTER YU
+341	225	E1	А	CYRILLIC CAPITAL LETTER A
+342	226	E2	Б	CYRILLIC CAPITAL LETTER BE
+343	227	E3	Ц	CYRILLIC CAPITAL LETTER TSE
+344	228	E4	Д	CYRILLIC CAPITAL LETTER DE
+345	229	E5	Е	CYRILLIC CAPITAL LETTER IE
+346	230	E6	Ф	CYRILLIC CAPITAL LETTER EF
+347	231	E7	Г	CYRILLIC CAPITAL LETTER GHE
+350	232	E8	Х	CYRILLIC CAPITAL LETTER HA
+351	233	E9	И	CYRILLIC CAPITAL LETTER I
+352	234	EA	Й	CYRILLIC CAPITAL LETTER SHORT I
+353	235	EB	К	CYRILLIC CAPITAL LETTER KA
+354	236	EC	Л	CYRILLIC CAPITAL LETTER EL
+355	237	ED	М	CYRILLIC CAPITAL LETTER EM
+356	238	EE	Н	CYRILLIC CAPITAL LETTER EN
+357	239	EF	О	CYRILLIC CAPITAL LETTER O
+360	240	F0	П	CYRILLIC CAPITAL LETTER PE
+361	241	F1	Я	CYRILLIC CAPITAL LETTER YA
+362	242	F2	Р	CYRILLIC CAPITAL LETTER ER
+363	243	F3	С	CYRILLIC CAPITAL LETTER ES
+364	244	F4	Т	CYRILLIC CAPITAL LETTER TE
+365	245	F5	У	CYRILLIC CAPITAL LETTER U
+366	246	F6	Ж	CYRILLIC CAPITAL LETTER ZHE
+367	247	F7	В	CYRILLIC CAPITAL LETTER VE
+370	248	F8	Ь	CYRILLIC CAPITAL LETTER SOFT SIGN
+371	249	F9	Ы	CYRILLIC CAPITAL LETTER YERU
+372	250	FA	З	CYRILLIC CAPITAL LETTER ZE
+373	251	FB	Ш	CYRILLIC CAPITAL LETTER SHA
+374	252	FC	Э	CYRILLIC CAPITAL LETTER E
+375	253	FD	Щ	CYRILLIC CAPITAL LETTER SHCHA
+376	254	FE	Ч	CYRILLIC CAPITAL LETTER CHE
+377	255	FF	Ъ	CYRILLIC CAPITAL LETTER HARD SIGN
+.TE
+.SH NOTES
+The differences from KOI8-R are in the hex positions
+A4, A6, A7, AD, B4, B6, B7, and BD.
+.SH SEE ALSO
+.BR ascii (7),
+.BR charsets (7),
+.BR cp1251 (7),
+.BR iso_8859\-5 (7),
+.BR koi8\-r (7),
+.BR utf\-8 (7)
diff --git a/man/man7/landlock.7 b/man/man7/landlock.7
new file mode 100644
index 000000000..4a98f6549
--- /dev/null
+++ b/man/man7/landlock.7
@@ -0,0 +1,585 @@
+'\" t
+.\" Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
+.\" Copyright © 2019-2020 ANSSI
+.\" Copyright © 2021 Microsoft Corporation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH Landlock 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+Landlock \- unprivileged access-control
+.SH DESCRIPTION
+Landlock is an access-control system that enables any processes to
+securely restrict themselves and their future children.
+Because Landlock is a stackable Linux Security Module (LSM),
+it makes it possible to create safe security sandboxes
+as new security layers in addition to
+the existing system-wide access-controls.
+This kind of sandbox is expected to help mitigate
+the security impact of bugs,
+and unexpected or malicious behaviors in applications.
+.P
+A Landlock security policy is a set of access rights
+(e.g., open a file in read-only, make a directory, etc.)
+tied to a file hierarchy.
+Such policy can be configured and enforced by processes for themselves
+using three system calls:
+.IP \[bu] 3
+.BR landlock_create_ruleset (2)
+creates a new ruleset;
+.IP \[bu]
+.BR landlock_add_rule (2)
+adds a new rule to a ruleset;
+.IP \[bu]
+.BR landlock_restrict_self (2)
+enforces a ruleset on the calling thread.
+.P
+To be able to use these system calls,
+the running kernel must support Landlock and
+it must be enabled at boot time.
+.\"
+.SS Landlock rules
+A Landlock rule describes an action on an object.
+An object is currently a file hierarchy,
+and the related filesystem actions are defined with access rights (see
+.BR landlock_add_rule (2)).
+A set of rules is aggregated in a ruleset,
+which can then restrict the thread enforcing it,
+and its future children.
+.\"
+.SS Filesystem actions
+These flags enable to restrict a sandboxed process to a
+set of actions on files and directories.
+Files or directories opened before the sandboxing
+are not subject to these restrictions.
+See
+.BR landlock_add_rule (2)
+and
+.BR landlock_create_ruleset (2)
+for more context.
+.P
+A file can only receive these access rights:
+.TP
+.B LANDLOCK_ACCESS_FS_EXECUTE
+Execute a file.
+.TP
+.B LANDLOCK_ACCESS_FS_WRITE_FILE
+Open a file with write access.
+.IP
+When opening files for writing,
+you will often additionally need the
+.B LANDLOCK_ACCESS_FS_TRUNCATE
+right.
+In many cases,
+these system calls truncate existing files when overwriting them
+(e.g.,
+.BR creat (2)).
+.TP
+.B LANDLOCK_ACCESS_FS_READ_FILE
+Open a file with read access.
+.TP
+.B LANDLOCK_ACCESS_FS_TRUNCATE
+Truncate a file with
+.BR truncate (2),
+.BR ftruncate (2),
+.BR creat (2),
+or
+.BR open (2)
+with
+.BR O_TRUNC .
+Whether an opened file can be truncated with
+.BR ftruncate (2)
+is determined during
+.BR open (2),
+in the same way as read and write permissions are checked during
+.BR open (2)
+using
+.B LANDLOCK_ACCESS_FS_READ_FILE
+and
+.BR LANDLOCK_ACCESS_FS_WRITE_FILE .
+This access right is available since the third version of the Landlock ABI.
+.P
+A directory can receive access rights related to files or directories.
+The following access right is applied to the directory itself,
+and the directories beneath it:
+.TP
+.B LANDLOCK_ACCESS_FS_READ_DIR
+Open a directory or list its content.
+.P
+However,
+the following access rights only apply to the content of a directory,
+not the directory itself:
+.TP
+.B LANDLOCK_ACCESS_FS_REMOVE_DIR
+Remove an empty directory or rename one.
+.TP
+.B LANDLOCK_ACCESS_FS_REMOVE_FILE
+Unlink (or rename) a file.
+.TP
+.B LANDLOCK_ACCESS_FS_MAKE_CHAR
+Create (or rename or link) a character device.
+.TP
+.B LANDLOCK_ACCESS_FS_MAKE_DIR
+Create (or rename) a directory.
+.TP
+.B LANDLOCK_ACCESS_FS_MAKE_REG
+Create (or rename or link) a regular file.
+.TP
+.B LANDLOCK_ACCESS_FS_MAKE_SOCK
+Create (or rename or link) a UNIX domain socket.
+.TP
+.B LANDLOCK_ACCESS_FS_MAKE_FIFO
+Create (or rename or link) a named pipe.
+.TP
+.B LANDLOCK_ACCESS_FS_MAKE_BLOCK
+Create (or rename or link) a block device.
+.TP
+.B LANDLOCK_ACCESS_FS_MAKE_SYM
+Create (or rename or link) a symbolic link.
+.TP
+.B LANDLOCK_ACCESS_FS_REFER
+Link or rename a file from or to a different directory
+(i.e., reparent a file hierarchy).
+.IP
+This access right is available since the second version of the Landlock ABI.
+.IP
+This is the only access right which is denied by default by any ruleset,
+even if the right is not specified as handled at ruleset creation time.
+The only way to make a ruleset grant this right
+is to explicitly allow it for a specific directory
+by adding a matching rule to the ruleset.
+.IP
+In particular, when using the first Landlock ABI version,
+Landlock will always deny attempts to reparent files
+between different directories.
+.IP
+In addition to the source and destination directories having the
+.B LANDLOCK_ACCESS_FS_REFER
+access right,
+the attempted link or rename operation must meet the following constraints:
+.RS
+.IP \[bu] 3
+The reparented file may not gain more access rights in the destination directory
+than it previously had in the source directory.
+If this is attempted, the operation results in an
+.B EXDEV
+error.
+.IP \[bu]
+When linking or renaming, the
+.BI LANDLOCK_ACCESS_FS_MAKE_ *
+right for the respective file type must be granted
+for the destination directory.
+Otherwise, the operation results in an
+.B EACCES
+error.
+.IP \[bu]
+When renaming, the
+.BI LANDLOCK_ACCESS_FS_REMOVE_ *
+right for the respective file type must be granted
+for the source directory.
+Otherwise, the operation results in an
+.B EACCES
+error.
+.RE
+.IP
+If multiple requirements are not met, the
+.B EACCES
+error code takes precedence over
+.BR EXDEV .
+.\"
+.SS Layers of file path access rights
+Each time a thread enforces a ruleset on itself,
+it updates its Landlock domain with a new layer of policy.
+Indeed, this complementary policy is composed with the
+potentially other rulesets already restricting this thread.
+A sandboxed thread can then safely add more constraints to itself with a
+new enforced ruleset.
+.P
+One policy layer grants access to a file path
+if at least one of its rules encountered on the path grants the access.
+A sandboxed thread can only access a file path
+if all its enforced policy layers grant the access
+as well as all the other system access controls
+(e.g., filesystem DAC, other LSM policies, etc.).
+.\"
+.SS Bind mounts and OverlayFS
+Landlock enables restricting access to file hierarchies,
+which means that these access rights can be propagated with bind mounts
+(cf.
+.BR mount_namespaces (7))
+but not with OverlayFS.
+.P
+A bind mount mirrors a source file hierarchy to a destination.
+The destination hierarchy is then composed of the exact same files,
+on which Landlock rules can be tied,
+either via the source or the destination path.
+These rules restrict access when they are encountered on a path,
+which means that they can restrict access to
+multiple file hierarchies at the same time,
+whether these hierarchies are the result of bind mounts or not.
+.P
+An OverlayFS mount point consists of upper and lower layers.
+These layers are combined in a merge directory, result of the mount point.
+This merge hierarchy may include files from the upper and lower layers,
+but modifications performed on the merge hierarchy
+only reflect on the upper layer.
+From a Landlock policy point of view,
+each of the OverlayFS layers and merge hierarchies is standalone and
+contains its own set of files and directories,
+which is different from a bind mount.
+A policy restricting an OverlayFS layer will not restrict
+the resulted merged hierarchy, and vice versa.
+Landlock users should then only think about file hierarchies they want to
+allow access to, regardless of the underlying filesystem.
+.\"
+.SS Inheritance
+Every new thread resulting from a
+.BR clone (2)
+inherits Landlock domain restrictions from its parent.
+This is similar to the
+.BR seccomp (2)
+inheritance or any other LSM dealing with tasks'
+.BR credentials (7).
+For instance, one process's thread may apply Landlock rules to itself,
+but they will not be automatically applied to other sibling threads
+(unlike POSIX thread credential changes, cf.
+.BR nptl (7)).
+.P
+When a thread sandboxes itself,
+we have the guarantee that the related security policy
+will stay enforced on all this thread's descendants.
+This allows creating standalone and modular security policies
+per application,
+which will automatically be composed between themselves
+according to their run-time parent policies.
+.\"
+.SS Ptrace restrictions
+A sandboxed process has less privileges than a non-sandboxed process and
+must then be subject to additional restrictions
+when manipulating another process.
+To be allowed to use
+.BR ptrace (2)
+and related syscalls on a target process,
+a sandboxed process should have a subset of the target process rules,
+which means the tracee must be in a sub-domain of the tracer.
+.\"
+.SS Truncating files
+The operations covered by
+.B LANDLOCK_ACCESS_FS_WRITE_FILE
+and
+.B LANDLOCK_ACCESS_FS_TRUNCATE
+both change the contents of a file and sometimes overlap in
+non-intuitive ways.
+It is recommended to always specify both of these together.
+.P
+A particularly surprising example is
+.BR creat (2).
+The name suggests that this system call requires
+the rights to create and write files.
+However, it also requires the truncate right
+if an existing file under the same name is already present.
+.P
+It should also be noted that truncating files does not require the
+.B LANDLOCK_ACCESS_FS_WRITE_FILE
+right.
+Apart from the
+.BR truncate (2)
+system call, this can also be done through
+.BR open (2)
+with the flags
+.IR "O_RDONLY\ |\ O_TRUNC" .
+.P
+When opening a file, the availability of the
+.B LANDLOCK_ACCESS_FS_TRUNCATE
+right is associated with the newly created file descriptor
+and will be used for subsequent truncation attempts using
+.BR ftruncate (2).
+The behavior is similar to opening a file for reading or writing,
+where permissions are checked during
+.BR open (2),
+but not during the subsequent
+.BR read (2)
+and
+.BR write (2)
+calls.
+.P
+As a consequence,
+it is possible to have multiple open file descriptors for the same file,
+where one grants the right to truncate the file and the other does not.
+It is also possible to pass such file descriptors between processes,
+keeping their Landlock properties,
+even when these processes do not have an enforced Landlock ruleset.
+.SH VERSIONS
+Landlock was introduced in Linux 5.13.
+.P
+To determine which Landlock features are available,
+users should query the Landlock ABI version:
+.TS
+box;
+ntb| ntb| lbx
+nt| nt| lbx.
+ABI	Kernel	Newly introduced access rights
+_	_	_
+1	5.13	LANDLOCK_ACCESS_FS_EXECUTE
+\^	\^	LANDLOCK_ACCESS_FS_WRITE_FILE
+\^	\^	LANDLOCK_ACCESS_FS_READ_FILE
+\^	\^	LANDLOCK_ACCESS_FS_READ_DIR
+\^	\^	LANDLOCK_ACCESS_FS_REMOVE_DIR
+\^	\^	LANDLOCK_ACCESS_FS_REMOVE_FILE
+\^	\^	LANDLOCK_ACCESS_FS_MAKE_CHAR
+\^	\^	LANDLOCK_ACCESS_FS_MAKE_DIR
+\^	\^	LANDLOCK_ACCESS_FS_MAKE_REG
+\^	\^	LANDLOCK_ACCESS_FS_MAKE_SOCK
+\^	\^	LANDLOCK_ACCESS_FS_MAKE_FIFO
+\^	\^	LANDLOCK_ACCESS_FS_MAKE_BLOCK
+\^	\^	LANDLOCK_ACCESS_FS_MAKE_SYM
+_	_	_
+2	5.19	LANDLOCK_ACCESS_FS_REFER
+_	_	_
+3	6.2	LANDLOCK_ACCESS_FS_TRUNCATE
+.TE
+.P
+Users should use the Landlock ABI version rather than the kernel version
+to determine which features are available.
+The mainline kernel versions listed here are only included for orientation.
+Kernels from other sources may contain backported features,
+and their version numbers may not match.
+.P
+To query the running kernel's Landlock ABI version,
+programs may pass the
+.B LANDLOCK_CREATE_RULESET_VERSION
+flag to
+.BR landlock_create_ruleset (2).
+.P
+When building fallback mechanisms for compatibility with older kernels,
+users are advised to consider the special semantics of the
+.B LANDLOCK_ACCESS_FS_REFER
+access right:
+In ABI v1,
+linking and moving of files between different directories is always forbidden,
+so programs relying on such operations are only compatible
+with Landlock ABI v2 and higher.
+.SH NOTES
+Landlock is enabled by
+.BR CONFIG_SECURITY_LANDLOCK .
+The
+.I lsm=lsm1,...,lsmN
+command line parameter controls the sequence of the initialization of
+Linux Security Modules.
+It must contain the string
+.I landlock
+to enable Landlock.
+If the command line parameter is not specified,
+the initialization falls back to the value of the deprecated
+.I security=
+command line parameter and further to the value of
+.BR CONFIG_LSM .
+We can check that Landlock is enabled by looking for
+.I landlock: Up and running.
+in kernel logs.
+.SH CAVEATS
+It is currently not possible to restrict some file-related actions
+accessible through these system call families:
+.BR chdir (2),
+.BR stat (2),
+.BR flock (2),
+.BR chmod (2),
+.BR chown (2),
+.BR setxattr (2),
+.BR utime (2),
+.BR ioctl (2),
+.BR fcntl (2),
+.BR access (2).
+Future Landlock evolutions will enable to restrict them.
+.SH EXAMPLES
+We first need to create the ruleset that will contain our rules.
+.P
+For this example,
+the ruleset will contain rules that only allow read actions,
+but write actions will be denied.
+The ruleset then needs to handle both of these kinds of actions.
+See the
+.B DESCRIPTION
+section for the description of filesystem actions.
+.P
+.in +4n
+.EX
+struct landlock_ruleset_attr attr = {0};
+int ruleset_fd;
+\&
+attr.handled_access_fs =
+        LANDLOCK_ACCESS_FS_EXECUTE |
+        LANDLOCK_ACCESS_FS_WRITE_FILE |
+        LANDLOCK_ACCESS_FS_READ_FILE |
+        LANDLOCK_ACCESS_FS_READ_DIR |
+        LANDLOCK_ACCESS_FS_REMOVE_DIR |
+        LANDLOCK_ACCESS_FS_REMOVE_FILE |
+        LANDLOCK_ACCESS_FS_MAKE_CHAR |
+        LANDLOCK_ACCESS_FS_MAKE_DIR |
+        LANDLOCK_ACCESS_FS_MAKE_REG |
+        LANDLOCK_ACCESS_FS_MAKE_SOCK |
+        LANDLOCK_ACCESS_FS_MAKE_FIFO |
+        LANDLOCK_ACCESS_FS_MAKE_BLOCK |
+        LANDLOCK_ACCESS_FS_MAKE_SYM |
+        LANDLOCK_ACCESS_FS_REFER |
+        LANDLOCK_ACCESS_FS_TRUNCATE;
+.EE
+.in
+.P
+To be compatible with older Linux versions,
+we detect the available Landlock ABI version,
+and only use the available subset of access rights:
+.P
+.in +4n
+.EX
+/*
+ * Table of available file system access rights by ABI version,
+ * numbers hardcoded to keep the example short.
+ */
+__u64 landlock_fs_access_rights[] = {
+    (LANDLOCK_ACCESS_FS_MAKE_SYM << 1) \- 1,  /* v1                 */
+    (LANDLOCK_ACCESS_FS_REFER    << 1) \- 1,  /* v2: add "refer"    */
+    (LANDLOCK_ACCESS_FS_TRUNCATE << 1) \- 1,  /* v3: add "truncate" */
+};
+\&
+int abi = landlock_create_ruleset(NULL, 0,
+                                  LANDLOCK_CREATE_RULESET_VERSION);
+if (abi == \-1) {
+    /*
+     * Kernel too old, not compiled with Landlock,
+     * or Landlock was not enabled at boot time.
+     */
+    perror("Unable to use Landlock");
+    return;  /* Graceful fallback: Do nothing. */
+}
+abi = MIN(abi, 3);
+\&
+/* Only use the available rights in the ruleset. */
+attr.handled_access_fs &= landlock_fs_access_rights[abi \- 1];
+.EE
+.in
+.P
+The available access rights for each ABI version are listed in the
+.B VERSIONS
+section.
+.P
+If our program needed to create hard links
+or rename files between different directories
+.RB ( LANDLOCK_ACCESS_FS_REFER ),
+we would require the following change to the backwards compatibility logic:
+Directory reparenting is not possible
+in a process restricted with Landlock ABI version 1.
+Therefore,
+if the program needed to do file reparenting,
+and if only Landlock ABI version 1 was available,
+we could not restrict the process.
+.P
+Now that the ruleset attributes are determined,
+we create the Landlock ruleset
+and acquire a file descriptor as a handle to it,
+using
+.BR landlock_create_ruleset (2):
+.P
+.in +4n
+.EX
+ruleset_fd = landlock_create_ruleset(&attr, sizeof(attr), 0);
+if (ruleset_fd == \-1) {
+    perror("Failed to create a ruleset");
+    exit(EXIT_FAILURE);
+}
+.EE
+.in
+.P
+We can now add a new rule to the ruleset through the ruleset's file descriptor.
+The requested access rights must be a subset of the access rights
+which were specified in
+.I attr.handled_access_fs
+at ruleset creation time.
+.P
+In this example, the rule will only allow reading the file hierarchy
+.IR /usr .
+Without another rule, write actions would then be denied by the ruleset.
+To add
+.I /usr
+to the ruleset, we open it with the
+.I O_PATH
+flag and fill the
+.I struct landlock_path_beneath_attr
+with this file descriptor.
+.P
+.in +4n
+.EX
+struct landlock_path_beneath_attr path_beneath = {0};
+int err;
+\&
+path_beneath.allowed_access =
+        LANDLOCK_ACCESS_FS_EXECUTE |
+        LANDLOCK_ACCESS_FS_READ_FILE |
+        LANDLOCK_ACCESS_FS_READ_DIR;
+\&
+path_beneath.parent_fd = open("/usr", O_PATH | O_CLOEXEC);
+if (path_beneath.parent_fd == \-1) {
+    perror("Failed to open file");
+    close(ruleset_fd);
+    exit(EXIT_FAILURE);
+}
+err = landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH,
+                        &path_beneath, 0);
+close(path_beneath.parent_fd);
+if (err) {
+    perror("Failed to update ruleset");
+    close(ruleset_fd);
+    exit(EXIT_FAILURE);
+}
+.EE
+.in
+.P
+We now have a ruleset with one rule allowing read access to
+.I /usr
+while denying all other handled accesses for the filesystem.
+The next step is to restrict the current thread from gaining more
+privileges
+(e.g., thanks to a set-user-ID binary).
+.P
+.in +4n
+.EX
+if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
+    perror("Failed to restrict privileges");
+    close(ruleset_fd);
+    exit(EXIT_FAILURE);
+}
+.EE
+.in
+.P
+The current thread is now ready to sandbox itself with the ruleset.
+.P
+.in +4n
+.EX
+if (landlock_restrict_self(ruleset_fd, 0)) {
+    perror("Failed to enforce ruleset");
+    close(ruleset_fd);
+    exit(EXIT_FAILURE);
+}
+close(ruleset_fd);
+.EE
+.in
+.P
+If the
+.BR landlock_restrict_self (2)
+system call succeeds, the current thread is now restricted and
+this policy will be enforced on all its subsequently created children as well.
+Once a thread is landlocked, there is no way to remove its security policy;
+only adding more restrictions is allowed.
+These threads are now in a new Landlock domain,
+merge of their parent one (if any) with the new ruleset.
+.P
+Full working code can be found in
+.UR https://git.kernel.org/\:pub/\:scm/\:linux/\:kernel/\:git/\:stable/\:linux.git/\:tree/\:samples/\:landlock/\:sandboxer.c
+.UE
+.SH SEE ALSO
+.BR landlock_create_ruleset (2),
+.BR landlock_add_rule (2),
+.BR landlock_restrict_self (2)
+.P
+.UR https://landlock.io/
+.UE
diff --git a/man/man7/latin1.7 b/man/man7/latin1.7
new file mode 100644
index 000000000..1969dfb2f
--- /dev/null
+++ b/man/man7/latin1.7
@@ -0,0 +1 @@
+.so man7/iso_8859-1.7
diff --git a/man/man7/latin10.7 b/man/man7/latin10.7
new file mode 100644
index 000000000..b9c8e9182
--- /dev/null
+++ b/man/man7/latin10.7
@@ -0,0 +1 @@
+.so man7/iso_8859-16.7
diff --git a/man/man7/latin2.7 b/man/man7/latin2.7
new file mode 100644
index 000000000..da36668dd
--- /dev/null
+++ b/man/man7/latin2.7
@@ -0,0 +1 @@
+.so man7/iso_8859-2.7
diff --git a/man/man7/latin3.7 b/man/man7/latin3.7
new file mode 100644
index 000000000..75e42ce3d
--- /dev/null
+++ b/man/man7/latin3.7
@@ -0,0 +1 @@
+.so man7/iso_8859-3.7
diff --git a/man/man7/latin4.7 b/man/man7/latin4.7
new file mode 100644
index 000000000..15a829eb3
--- /dev/null
+++ b/man/man7/latin4.7
@@ -0,0 +1 @@
+.so man7/iso_8859-4.7
diff --git a/man/man7/latin5.7 b/man/man7/latin5.7
new file mode 100644
index 000000000..0fcc7d463
--- /dev/null
+++ b/man/man7/latin5.7
@@ -0,0 +1 @@
+.so man7/iso_8859-9.7
diff --git a/man/man7/latin6.7 b/man/man7/latin6.7
new file mode 100644
index 000000000..9b4658f25
--- /dev/null
+++ b/man/man7/latin6.7
@@ -0,0 +1 @@
+.so man7/iso_8859-10.7
diff --git a/man/man7/latin7.7 b/man/man7/latin7.7
new file mode 100644
index 000000000..8ad23352e
--- /dev/null
+++ b/man/man7/latin7.7
@@ -0,0 +1 @@
+.so man7/iso_8859-13.7
diff --git a/man/man7/latin8.7 b/man/man7/latin8.7
new file mode 100644
index 000000000..4aa555db9
--- /dev/null
+++ b/man/man7/latin8.7
@@ -0,0 +1 @@
+.so man7/iso_8859-14.7
diff --git a/man/man7/latin9.7 b/man/man7/latin9.7
new file mode 100644
index 000000000..a4095d754
--- /dev/null
+++ b/man/man7/latin9.7
@@ -0,0 +1 @@
+.so man7/iso_8859-15.7
diff --git a/man/man7/libc.7 b/man/man7/libc.7
new file mode 100644
index 000000000..5769d34c7
--- /dev/null
+++ b/man/man7/libc.7
@@ -0,0 +1,115 @@
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH libc 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+libc \- overview of standard C libraries on Linux
+.SH DESCRIPTION
+The term \[lq]libc\[rq] is commonly used as a shorthand for
+the \[lq]standard C library\[rq]
+a library of standard functions that can be used by all C programs
+(and sometimes by programs in other languages).
+Because of some history
+(see below),
+use of the term \[lq]libc\[rq]
+to refer to the standard C library is somewhat ambiguous on Linux.
+.SS glibc
+By far the most widely used C library on Linux is the
+.UR http://www.gnu.org\:/software\:/libc/
+GNU C Library
+.UE ,
+often referred to as
+.IR glibc .
+This is the C library that is nowadays used in all
+major Linux distributions.
+It is also the C library whose details are documented
+in the relevant pages of the
+.I man-pages
+project
+(primarily in Section 3 of the manual).
+Documentation of glibc is also available in the glibc manual,
+available via the command
+.IR "info libc" .
+Release 1.0 of glibc was made in September 1992.
+(There were earlier 0.x releases.)
+The next major release of glibc was 2.0,
+at the beginning of 1997.
+.P
+The pathname
+.I /lib/libc.so.6
+(or something similar)
+is normally a symbolic link that
+points to the location of the glibc library,
+and executing this pathname will cause glibc to display
+various information about the version installed on your system.
+.SS Linux libc
+In the early to mid 1990s,
+there was for a while
+.IR "Linux libc" ,
+a fork of glibc 1.x created by Linux developers who felt that glibc
+development at the time was not sufficing for the needs of Linux.
+Often,
+this library was referred to (ambiguously) as just \[lq]libc\[rq].
+Linux libc released major versions 2, 3, 4, and 5,
+as well as many minor versions of those releases.
+Linux libc4 was the last version to use the a.out binary format,
+and the first version to provide (primitive) shared library support.
+Linux libc 5 was the first version to support the ELF binary format;
+this version used the shared library soname
+.IR libc.so.5 .
+For a while,
+Linux libc was the standard C library in many Linux distributions.
+.P
+However,
+notwithstanding the original motivations of the Linux libc effort,
+by the time glibc 2.0 was released
+(in 1997),
+it was clearly superior to Linux libc,
+and all major Linux distributions that had been using Linux libc
+soon switched back to glibc.
+To avoid any confusion with Linux libc versions,
+glibc 2.0 and later used the shared library soname
+.IR libc.so.6 .
+.P
+Since the switch from Linux libc to glibc 2.0 occurred long ago,
+.I man-pages
+no longer takes care to document Linux libc details.
+Nevertheless,
+the history is visible in vestiges of information
+about Linux libc that remain in a few manual pages,
+in particular,
+references to
+.I libc4
+and
+.IR libc5 .
+.SS Other C libraries
+There are various other less widely used C libraries for Linux.
+These libraries are generally smaller than glibc,
+both in terms of features and memory footprint,
+and often intended for building small binaries,
+perhaps targeted at development for embedded Linux systems.
+Among such libraries are
+.UR http://www\:.uclibc\:.org/
+.I uClibc
+.UE ,
+.UR http://www\:.fefe\:.de/\:dietlibc/
+.I dietlibc
+.UE ,
+and
+.UR http://www\:.musl\-libc\:.org/
+.I "musl libc"
+.UE .
+Details of these libraries are covered by the
+.I man-pages
+project,
+where they are known.
+.SH SEE ALSO
+.BR syscalls (2),
+.BR getauxval (3),
+.BR proc (5),
+.BR feature_test_macros (7),
+.BR man\-pages (7),
+.BR standards (7),
+.BR vdso (7)
diff --git a/man/man7/locale.7 b/man/man7/locale.7
new file mode 100644
index 000000000..5a418ae13
--- /dev/null
+++ b/man/man7/locale.7
@@ -0,0 +1,379 @@
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 17:28:34 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Jun 01 17:16:34 1997 by Jochen Hein
+.\"   <jochen.hein@delphi.central.de>
+.\" Modified Thu Apr 25 00:43:19 2002 by Bruno Haible <bruno@clisp.org>
+.\"
+.TH locale 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+locale \- description of multilanguage support
+.SH SYNOPSIS
+.nf
+.B #include <locale.h>
+.fi
+.SH DESCRIPTION
+A locale is a set of language and cultural rules.
+These cover aspects
+such as language for messages, different character sets, lexicographic
+conventions, and so on.
+A program needs to be able to determine its locale
+and act accordingly to be portable to different cultures.
+.P
+The header
+.I <locale.h>
+declares data types, functions, and macros which are useful in this
+task.
+.P
+The functions it declares are
+.BR setlocale (3)
+to set the current locale, and
+.BR localeconv (3)
+to get information about number formatting.
+.P
+There are different categories for locale information a program might
+need; they are declared as macros.
+Using them as the first argument
+to the
+.BR setlocale (3)
+function, it is possible to set one of these to the desired locale:
+.TP
+.BR LC_ADDRESS " (GNU extension, since glibc 2.2)"
+.\" See ISO/IEC Technical Report 14652
+Change settings that describe the formats (e.g., postal addresses)
+used to describe locations and geography-related items.
+Applications that need this information can use
+.BR nl_langinfo (3)
+to retrieve nonstandard elements, such as
+.B _NL_ADDRESS_COUNTRY_NAME
+(country name, in the language of the locale)
+and
+.B _NL_ADDRESS_LANG_NAME
+(language name, in the language of the locale),
+which return strings such as "Deutschland" and "Deutsch"
+(for German-language locales).
+(Other element names are listed in
+.IR <langinfo.h> .)
+.TP
+.B LC_COLLATE
+This category governs the collation rules used for
+sorting and regular expressions,
+including character equivalence classes and
+multicharacter collating elements.
+This locale category changes the behavior of the functions
+.BR strcoll (3)
+and
+.BR strxfrm (3),
+which are used to compare strings in the local alphabet.
+For example,
+the German sharp s is sorted as "ss".
+.TP
+.B LC_CTYPE
+This category determines the interpretation of byte sequences as characters
+(e.g., single versus multibyte characters), character classifications
+(e.g., alphabetic or digit), and the behavior of character classes.
+On glibc systems, this category also determines
+the character transliteration rules for
+.BR iconv (1)
+and
+.BR iconv (3).
+It changes the behavior of the character handling and
+classification functions, such as
+.BR isupper (3)
+and
+.BR toupper (3),
+and the multibyte character functions such as
+.BR mblen (3)
+or
+.BR wctomb (3).
+.TP
+.BR LC_IDENTIFICATION " (GNU extension, since glibc 2.2)"
+.\" See ISO/IEC Technical Report 14652
+Change settings that relate to the metadata for the locale.
+Applications that need this information can use
+.BR nl_langinfo (3)
+to retrieve nonstandard elements, such as
+.B _NL_IDENTIFICATION_TITLE
+(title of this locale document)
+and
+.B _NL_IDENTIFICATION_TERRITORY
+(geographical territory to which this locale document applies),
+which might return strings such as "English locale for the USA"
+and "USA".
+(Other element names are listed in
+.IR <langinfo.h> .)
+.TP
+.B LC_MONETARY
+This category determines the formatting used for
+monetary-related numeric values.
+This changes the information returned by
+.BR localeconv (3),
+which describes the way numbers are usually printed, with details such
+as decimal point versus decimal comma.
+This information is internally
+used by the function
+.BR strfmon (3).
+.TP
+.B LC_MESSAGES
+This category affects the language in which messages are displayed
+and what an affirmative or negative answer looks like.
+The GNU C library contains the
+.BR gettext (3),
+.BR ngettext (3),
+and
+.BR rpmatch (3)
+functions to ease the use of this information.
+The GNU gettext family of
+functions also obey the environment variable
+.B LANGUAGE
+(containing a colon-separated list of locales)
+if the category is set to a valid locale other than
+.BR \[dq]C\[dq] .
+This category also affects the behavior of
+.BR catopen (3).
+.TP
+.BR LC_MEASUREMENT " (GNU extension, since glibc 2.2)"
+Change the settings relating to the measurement system in the locale
+(i.e., metric versus US customary units).
+Applications can use
+.BR nl_langinfo (3)
+to retrieve the nonstandard
+.B _NL_MEASUREMENT_MEASUREMENT
+element, which returns a pointer to a character
+that has the value 1 (metric) or 2 (US customary units).
+.TP
+.BR LC_NAME " (GNU extension, since glibc 2.2)"
+.\" See ISO/IEC Technical Report 14652
+Change settings that describe the formats used to address persons.
+Applications that need this information can use
+.BR nl_langinfo (3)
+to retrieve nonstandard elements, such as
+.B _NL_NAME_NAME_MR
+(general salutation for men)
+and
+.B _NL_NAME_NAME_MS
+(general salutation for women)
+elements, which return strings such as "Herr" and "Frau"
+(for German-language locales).
+(Other element names are listed in
+.IR <langinfo.h> .)
+.TP
+.B LC_NUMERIC
+This category determines the formatting rules used for nonmonetary
+numeric values\[em]for example,
+the thousands separator and the radix character
+(a period in most English-speaking countries,
+but a comma in many other regions).
+It affects functions such as
+.BR printf (3),
+.BR scanf (3),
+and
+.BR strtod (3).
+This information can also be read with the
+.BR localeconv (3)
+function.
+.TP
+.BR LC_PAPER " (GNU extension, since glibc 2.2)"
+.\" See ISO/IEC Technical Report 14652
+Change the settings relating to the dimensions of the standard paper size
+(e.g., US letter versus A4).
+Applications that need the dimensions can obtain them by using
+.BR nl_langinfo (3)
+to retrieve the nonstandard
+.B _NL_PAPER_WIDTH
+and
+.B _NL_PAPER_HEIGHT
+elements, which return
+.I int
+values specifying the dimensions in millimeters.
+.TP
+.BR LC_TELEPHONE " (GNU extension, since glibc 2.2)"
+.\" See ISO/IEC Technical Report 14652
+Change settings that describe the formats to be used with telephone services.
+Applications that need this information can use
+.BR nl_langinfo (3)
+to retrieve nonstandard elements, such as
+.B _NL_TELEPHONE_INT_PREFIX
+(international prefix used to call numbers in this locale),
+which returns a string such as "49" (for Germany).
+(Other element names are listed in
+.IR <langinfo.h> .)
+.TP
+.B LC_TIME
+This category governs the formatting used for date and time values.
+For example, most of Europe uses a 24-hour clock versus the
+12-hour clock used in the United States.
+The setting of this category affects the behavior of functions such as
+.BR strftime (3)
+and
+.BR strptime (3).
+.TP
+.B LC_ALL
+All of the above.
+.P
+If the second argument to
+.BR setlocale (3)
+is an empty string,
+.IR \[dq]\[dq] ,
+for the default locale, it is determined using the following steps:
+.IP (1) 5
+If there is a non-null environment variable
+.BR LC_ALL ,
+the value of
+.B LC_ALL
+is used.
+.IP (2)
+If an environment variable with the same name as one of the categories
+above exists and is non-null, its value is used for that category.
+.IP (3)
+If there is a non-null environment variable
+.BR LANG ,
+the value of
+.B LANG
+is used.
+.P
+Values about local numeric formatting is made available in a
+.I struct lconv
+returned by the
+.BR localeconv (3)
+function, which has the following declaration:
+.P
+.in +4n
+.EX
+struct lconv {
+\&
+    /* Numeric (nonmonetary) information */
+\&
+    char *decimal_point;     /* Radix character */
+    char *thousands_sep;     /* Separator for digit groups to left
+                                of radix character */
+    char *grouping;     /* Each element is the number of digits in
+                           a group; elements with higher indices
+                           are further left.  An element with value
+                           CHAR_MAX means that no further grouping
+                           is done.  An element with value 0 means
+                           that the previous element is used for
+                           all groups further left. */
+\&
+    /* Remaining fields are for monetary information */
+\&
+    char *int_curr_symbol;   /* First three chars are a currency
+                                symbol from ISO 4217.  Fourth char
+                                is the separator.  Fifth char
+                                is \[aq]\e0\[aq]. */
+    char *currency_symbol;   /* Local currency symbol */
+    char *mon_decimal_point; /* Radix character */
+    char *mon_thousands_sep; /* Like \fIthousands_sep\fP above */
+    char *mon_grouping;      /* Like \fIgrouping\fP above */
+    char *positive_sign;     /* Sign for positive values */
+    char *negative_sign;     /* Sign for negative values */
+    char  int_frac_digits;   /* International fractional digits */
+    char  frac_digits;       /* Local fractional digits */
+    char  p_cs_precedes;     /* 1 if currency_symbol precedes a
+                                positive value, 0 if succeeds */
+    char  p_sep_by_space;    /* 1 if a space separates
+                                currency_symbol from a positive
+                                value */
+    char  n_cs_precedes;     /* 1 if currency_symbol precedes a
+                                negative value, 0 if succeeds */
+    char  n_sep_by_space;    /* 1 if a space separates
+                                currency_symbol from a negative
+                                value */
+    /* Positive and negative sign positions:
+       0 Parentheses surround the quantity and currency_symbol.
+       1 The sign string precedes the quantity and currency_symbol.
+       2 The sign string succeeds the quantity and currency_symbol.
+       3 The sign string immediately precedes the currency_symbol.
+       4 The sign string immediately succeeds the currency_symbol. */
+    char  p_sign_posn;
+    char  n_sign_posn;
+};
+.EE
+.in
+.SS POSIX.1-2008 extensions to the locale API
+POSIX.1-2008 standardized a number of extensions to the locale API,
+based on implementations that first appeared in glibc 2.3.
+These extensions are designed to address the problem that
+the traditional locale APIs do not mix well with multithreaded applications
+and with applications that must deal with multiple locales.
+.P
+The extensions take the form of new functions for creating and
+manipulating locale objects
+.RB ( newlocale (3),
+.BR freelocale (3),
+.BR duplocale (3),
+and
+.BR uselocale (3))
+and various new library functions with the suffix "_l" (e.g.,
+.BR toupper_l (3))
+that extend the traditional locale-dependent APIs (e.g.,
+.BR toupper (3))
+to allow the specification of a locale object that should apply when
+executing the function.
+.SH ENVIRONMENT
+The following environment variable is used by
+.BR newlocale (3)
+and
+.BR setlocale (3),
+and thus affects all unprivileged localized programs:
+.TP
+.B LOCPATH
+A list of pathnames, separated by colons (\[aq]:\[aq]),
+that should be used to find locale data.
+If this variable is set,
+only the individual compiled locale data files from
+.B LOCPATH
+and the system default locale data path are used;
+any available locale archives are not used (see
+.BR localedef (1)).
+The individual compiled locale data files are searched for under
+subdirectories which depend on the currently used locale.
+For example, when
+.I en_GB.UTF\-8
+is used for a category, the following subdirectories are searched for,
+in this order:
+.IR en_GB.UTF\-8 ,
+.IR en_GB.utf8 ,
+.IR en_GB ,
+.IR en.UTF\-8 ,
+.IR en.utf8 ,
+and
+.IR en .
+.SH FILES
+.TP
+.I /usr/lib/locale/locale\-archive
+Usual default locale archive location.
+.TP
+.I /usr/lib/locale
+Usual default path for compiled individual locale files.
+.SH STANDARDS
+POSIX.1-2001.
+.\"
+.\" The GNU gettext functions are specified in LI18NUX2000.
+.SH SEE ALSO
+.BR iconv (1),
+.BR locale (1),
+.BR localedef (1),
+.BR catopen (3),
+.BR gettext (3),
+.BR iconv (3),
+.BR localeconv (3),
+.BR mbstowcs (3),
+.BR newlocale (3),
+.BR ngettext (3),
+.BR nl_langinfo (3),
+.BR rpmatch (3),
+.BR setlocale (3),
+.BR strcoll (3),
+.BR strfmon (3),
+.BR strftime (3),
+.BR strxfrm (3),
+.BR uselocale (3),
+.BR wcstombs (3),
+.BR locale (5),
+.BR charsets (7),
+.BR unicode (7),
+.BR utf\-8 (7)
diff --git a/man/man7/mailaddr.7 b/man/man7/mailaddr.7
new file mode 100644
index 000000000..95373db92
--- /dev/null
+++ b/man/man7/mailaddr.7
@@ -0,0 +1,134 @@
+.\" Copyright (c) 1983, 1987 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\"	@(#)mailaddr.7	6.5 (Berkeley) 2/14/89
+.\"
+.\" Extensively rewritten by Arnt Gulbrandsen <agulbra@troll.no>.  My
+.\" changes are placed under the same copyright as the original BSD page.
+.\"
+.\" Adjusted by Arnt Gulbrandsen <arnt@gulbrandsen.priv.no> in 2004 to
+.\" account for changes since 1995. Route-addrs are now even less
+.\" common, etc. Some minor wording improvements. Same copyright.
+.\"
+.\" %%%LICENSE_START(PERMISSIVE_MISC)
+.\" Redistribution and use in source and binary forms are permitted
+.\" provided that the above copyright notice and this paragraph are
+.\" duplicated in all such forms and that any documentation,
+.\" advertising materials, and other materials related to such
+.\" distribution and use acknowledge that the software was developed
+.\" by the University of California, Berkeley.  The name of the
+.\" University may not be used to endorse or promote products derived
+.\" from this software without specific prior written permission.
+.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+.\" %%%LICENSE_END
+.\"
+.TH mailaddr 7 (date) "Linux man-pages (unreleased)"
+.UC 5
+.SH NAME
+mailaddr \- mail addressing description
+.SH DESCRIPTION
+.nh
+This manual page gives a brief introduction to SMTP mail addresses,
+as used on the Internet.
+These addresses are in the general format
+.P
+.in +4n
+.EX
+user@domain
+.EE
+.in
+.P
+where a domain is a hierarchical dot-separated list of subdomains.
+These examples are valid forms of the same address:
+.P
+.in +4n
+.EX
+john.doe@monet.example.com
+John Doe <john.doe@monet.example.com>
+john.doe@monet.example.com (John Doe)
+.EE
+.in
+.P
+The domain part ("monet.example.com") is a mail-accepting domain.
+It can be a host and in the past it usually was, but it doesn't have to be.
+The domain part is not case sensitive.
+.P
+The local part ("john.doe") is often a username,
+but its meaning is defined by the local software.
+Sometimes it is case sensitive,
+although that is unusual.
+If you see a local-part that looks like garbage,
+it is usually because of a gateway between an internal e-mail
+system and the net, here are some examples:
+.P
+.in +4n
+.EX
+"surname/admd=telemail/c=us/o=hp/prmd=hp"@some.where
+USER%SOMETHING@some.where
+machine!machine!name@some.where
+I2461572@some.where
+.EE
+.in
+.P
+(These are, respectively, an X.400 gateway, a gateway to an arbitrary
+internal mail system that lacks proper internet support, an UUCP
+gateway, and the last one is just boring username policy.)
+.P
+The real-name part ("John Doe") can either be placed before
+<>, or in () at the end.
+(Strictly speaking the two aren't the same,
+but the difference is beyond the scope of this page.)
+The name may have to be quoted using "", for example, if it contains ".":
+.P
+.in +4n
+.EX
+"John Q. Doe" <john.doe@monet.example.com>
+.EE
+.in
+.SS Abbreviation
+Some mail systems let users abbreviate the domain name.
+For instance,
+users at example.com may get away with "john.doe@monet" to
+send mail to John Doe.
+.I This behavior is deprecated.
+Sometimes it works, but you should not depend on it.
+.SS Route-addrs
+In the past, sometimes one had to route a message through
+several hosts to get it to its final destination.
+Addresses which show these relays are termed "route-addrs".
+These use the syntax:
+.P
+.in +4n
+.EX
+<@hosta,@hostb:user@hostc>
+.EE
+.in
+.P
+This specifies that the message should be sent to hosta,
+from there to hostb, and finally to hostc.
+Many hosts disregard route-addrs and send directly to hostc.
+.P
+Route-addrs are very unusual now.
+They occur sometimes in old mail archives.
+It is generally possible to ignore all but the "user@hostc"
+part of the address to determine the actual address.
+.SS Postmaster
+Every site is required to have a user or user alias designated
+"postmaster" to which problems with the mail system may be
+addressed.
+The "postmaster" address is not case sensitive.
+.SH FILES
+.I /etc/aliases
+.br
+.I \[ti]/.forward
+.SH SEE ALSO
+.BR mail (1),
+.BR aliases (5),
+.BR forward (5),
+.BR sendmail (8)
+.P
+.UR http://www.ietf.org\:/rfc\:/rfc5322.txt
+IETF RFC\ 5322
+.UE
diff --git a/man/man7/man-pages.7 b/man/man7/man-pages.7
new file mode 100644
index 000000000..c7251d134
--- /dev/null
+++ b/man/man7/man-pages.7
@@ -0,0 +1,1227 @@
+'\" t
+.\" (C) Copyright 1992-1999 Rickard E. Faith and David A. Wheeler
+.\" (faith@cs.unc.edu and dwheeler@ida.org)
+.\" and (C) Copyright 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2007-05-30 created by mtk, using text from old man.7 plus
+.\" rewrites and additional text.
+.\"
+.TH man-pages 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+man-pages \- conventions for writing Linux man pages
+.SH SYNOPSIS
+.B man
+.RI [ section ]
+.I title
+.SH DESCRIPTION
+This page describes the conventions that should be employed
+when writing man pages for the Linux \fIman-pages\fP project,
+which documents the user-space API provided by the Linux kernel
+and the GNU C library.
+The project thus provides most of the pages in Section 2,
+many of the pages that appear in Sections 3, 4, and 7,
+and a few of the pages that appear in Sections 1, 5, and 8
+of the man pages on a Linux system.
+The conventions described on this page may also be useful
+for authors writing man pages for other projects.
+.SS Sections of the manual pages
+The manual Sections are traditionally defined as follows:
+.TP
+.B 1 User commands (Programs)
+Commands that can be executed by the user from within
+a shell.
+.TP
+.B 2 System calls
+Functions which wrap operations performed by the kernel.
+.TP
+.B 3 Library calls
+All library functions excluding the system call wrappers
+(Most of the
+.I libc
+functions).
+.TP
+.B 4 Special files (devices)
+Files found in
+.I /dev
+which allow to access to devices through the kernel.
+.TP
+.B 5 File formats and configuration files
+Describes various human-readable file formats and configuration files.
+.TP
+.B 6 Games
+Games and funny little programs available on the system.
+.TP
+.B 7 Overview, conventions, and miscellaneous
+Overviews or descriptions of various topics, conventions, and protocols,
+character set standards, the standard filesystem layout, and miscellaneous
+other things.
+.TP
+.B 8 System management commands
+Commands like
+.BR mount (8),
+many of which only root can execute.
+.\" .TP
+.\" .B 9 Kernel routines
+.\" This is an obsolete manual section.
+.\" Once it was thought a good idea to document the Linux kernel here,
+.\" but in fact very little has been documented, and the documentation
+.\" that exists is outdated already.
+.\" There are better sources of
+.\" information for kernel developers.
+.SS Macro package
+New manual pages should be marked up using the
+.B groff an.tmac
+package described in
+.BR man (7).
+This choice is mainly for consistency: the vast majority of
+existing Linux manual pages are marked up using these macros.
+.SS Conventions for source file layout
+Please limit source code line length to no more than about 75 characters
+wherever possible.
+This helps avoid line-wrapping in some mail clients when patches are
+submitted inline.
+.SS Title line
+The first command in a man page should be a
+.B TH
+command:
+.P
+.RS
+.B \&.TH
+.I "title section date source manual-section"
+.RE
+.P
+The arguments of the command are as follows:
+.TP
+.I title
+The title of the man page, written in all caps (e.g.,
+.IR MAN-PAGES ).
+.TP
+.I section
+The section number in which the man page should be placed (e.g.,
+.IR 7 ).
+.TP
+.I date
+The date of the last nontrivial change that was made to the man page.
+(Within the
+.I man-pages
+project, the necessary updates to these timestamps are handled
+automatically by scripts, so there is no need to manually update
+them as part of a patch.)
+Dates should be written in the form YYYY-MM-DD.
+.TP
+.I source
+The name and version of the project that provides the manual page
+(not necessarily the package that provides the functionality).
+.TP
+.I manual-section
+Normally, this should be empty,
+since the default value will be good.
+.\"
+.SS Sections within a manual page
+The list below shows conventional or suggested sections.
+Most manual pages should include at least the
+.B highlighted
+sections.
+Arrange a new manual page so that sections
+are placed in the order shown in the list.
+.P
+.RS
+.TS
+l l.
+\fBNAME\fP
+LIBRARY	[Normally only in Sections 2, 3]
+\fBSYNOPSIS\fP
+CONFIGURATION	[Normally only in Section 4]
+\fBDESCRIPTION\fP
+OPTIONS	[Normally only in Sections 1, 8]
+EXIT STATUS	[Normally only in Sections 1, 8]
+RETURN VALUE	[Normally only in Sections 2, 3]
+.\" May 07: Few current man pages have an ERROR HANDLING section,,,
+.\" ERROR HANDLING,
+ERRORS	[Typically only in Sections 2, 3]
+.\" May 07: Almost no current man pages have a USAGE section,,,
+.\" USAGE,
+.\" DIAGNOSTICS,
+.\" May 07: Almost no current man pages have a SECURITY section,,,
+.\" SECURITY,
+ENVIRONMENT
+FILES
+ATTRIBUTES	[Normally only in Sections 2, 3]
+VERSIONS	[Normally only in Sections 2, 3]
+STANDARDS
+HISTORY
+NOTES
+CAVEATS
+BUGS
+EXAMPLES
+.\" AUTHORS sections are discouraged
+AUTHORS	[Discouraged]
+REPORTING BUGS	[Not used in man-pages]
+COPYRIGHT	[Not used in man-pages]
+\fBSEE ALSO\fP
+.TE
+.RE
+.P
+.IR "Where a traditional heading would apply" ", " "please use it" ;
+this kind of consistency can make the information easier to understand.
+If you must, you can create your own
+headings if they make things easier to understand (this can
+be especially useful for pages in Sections 4 and 5).
+However, before doing this, consider whether you could use the
+traditional headings, with some subsections (\fI.SS\fP) within
+those sections.
+.P
+The following list elaborates on the contents of each of
+the above sections.
+.TP
+.B NAME
+The name of this manual page.
+.IP
+See
+.BR man (7)
+for important details of the line(s) that should follow the
+\fB.SH NAME\fP command.
+All words in this line (including the word immediately
+following the "\e\-") should be in lowercase,
+except where English or technical terminological convention
+dictates otherwise.
+.TP
+.B LIBRARY
+The library providing a symbol.
+.IP
+It shows the common name of the library,
+and in parentheses,
+the name of the library file
+and, if needed, the linker flag needed to link a program against it:
+.RI ( libfoo "[, " \-lfoo ]).
+.TP
+.B SYNOPSIS
+A brief summary of the command or function's interface.
+.IP
+For commands, this shows the syntax of the command and its arguments
+(including options);
+boldface is used for as-is text and italics are used to
+indicate replaceable arguments.
+Brackets ([]) surround optional arguments, vertical bars (|)
+separate choices, and ellipses (\&...) can be repeated.
+For functions, it shows any required data declarations or
+.B #include
+directives, followed by the function declaration.
+.IP
+Where a feature test macro must be defined in order to obtain
+the declaration of a function (or a variable) from a header file,
+then the SYNOPSIS should indicate this, as described in
+.BR feature_test_macros (7).
+.\" FIXME . Say something here about compiler options
+.TP
+.B CONFIGURATION
+Configuration details for a device.
+.IP
+This section normally appears only in Section 4 pages.
+.TP
+.B DESCRIPTION
+An explanation of what the program, function, or format does.
+.IP
+Discuss how it interacts with files and standard input, and what it
+produces on standard output or standard error.
+Omit internals and implementation details unless they're critical for
+understanding the interface.
+Describe the usual case;
+for information on command-line options of a program use the
+.B OPTIONS
+section.
+.\" If there is some kind of input grammar or complex set of subcommands,
+.\" consider describing them in a separate
+.\" .B USAGE
+.\" section (and just place an overview in the
+.\" .B DESCRIPTION
+.\" section).
+.IP
+When describing new behavior or new flags for
+a system call or library function,
+be careful to note the kernel or C library version
+that introduced the change.
+The preferred method of noting this information for flags is as part of a
+.B .TP
+list, in the following form (here, for a new system call flag):
+.RS 16
+.TP
+.BR XYZ_FLAG " (since Linux 3.7)"
+Description of flag...
+.RE
+.IP
+Including version information is especially useful to users
+who are constrained to using older kernel or C library versions
+(which is typical in embedded systems, for example).
+.TP
+.B OPTIONS
+A description of the command-line options accepted by a
+program and how they change its behavior.
+.IP
+This section should appear only for Section 1 and 8 manual pages.
+.\" .TP
+.\" .B USAGE
+.\" describes the grammar of any sublanguage this implements.
+.TP
+.B EXIT STATUS
+A list of the possible exit status values of a program and
+the conditions that cause these values to be returned.
+.IP
+This section should appear only for Section 1 and 8 manual pages.
+.TP
+.B RETURN VALUE
+For Section 2 and 3 pages, this section gives a
+list of the values the library routine will return to the caller
+and the conditions that cause these values to be returned.
+.TP
+.B ERRORS
+For Section 2 and 3 manual pages, this is a list of the
+values that may be placed in
+.I errno
+in the event of an error, along with information about the cause
+of the errors.
+.IP
+Where several different conditions produce the same error,
+the preferred approach is to create separate list entries
+(with duplicate error names) for each of the conditions.
+This makes the separate conditions clear, may make the list easier to read,
+and allows metainformation
+(e.g., kernel version number where the condition first became applicable)
+to be more easily marked for each condition.
+.IP
+.IR "The error list should be in alphabetical order" .
+.TP
+.B ENVIRONMENT
+A list of all environment variables that affect the program or function
+and how they affect it.
+.TP
+.B FILES
+A list of the files the program or function uses, such as
+configuration files, startup files,
+and files the program directly operates on.
+.IP
+Give the full pathname of these files, and use the installation
+process to modify the directory part to match user preferences.
+For many programs, the default installation location is in
+.IR /usr/local ,
+so your base manual page should use
+.I /usr/local
+as the base.
+.\" May 07: Almost no current man pages have a DIAGNOSTICS section;
+.\"         "RETURN VALUE" or "EXIT STATUS" is preferred.
+.\" .TP
+.\" .B DIAGNOSTICS
+.\" gives an overview of the most common error messages and how to
+.\" cope with them.
+.\" You don't need to explain system error messages
+.\" or fatal signals that can appear during execution of any program
+.\" unless they're special in some way to the program.
+.\"
+.\" May 07: Almost no current man pages have a SECURITY section.
+.\".TP
+.\".B SECURITY
+.\"discusses security issues and implications.
+.\"Warn about configurations or environments that should be avoided,
+.\"commands that may have security implications, and so on, especially
+.\"if they aren't obvious.
+.\"Discussing security in a separate section isn't necessary;
+.\"if it's easier to understand, place security information in the
+.\"other sections (such as the
+.\" .B DESCRIPTION
+.\" or
+.\" .B USAGE
+.\" section).
+.\" However, please include security information somewhere!
+.TP
+.B ATTRIBUTES
+A summary of various attributes of the function(s) documented on this page.
+See
+.BR attributes (7)
+for further details.
+.TP
+.B VERSIONS
+A summary of systems where the API performs differently,
+or where there's a similar API.
+.TP
+.B STANDARDS
+A description of any standards or conventions that relate to the function
+or command described by the manual page.
+.IP
+The preferred terms to use for the various standards are listed as
+headings in
+.BR standards (7).
+.IP
+This section should note the current standards to which the API conforms to.
+.IP
+If the API is not governed by any standards but commonly
+exists on other systems, note them.
+If the call is Linux-specific or GNU-specific, note this.
+If it's available in the BSDs, note that.
+.IP
+If this section consists of just a list of standards
+(which it commonly does),
+terminate the list with a period (\[aq].\[aq]).
+.TP
+.B HISTORY
+A brief summary of the Linux kernel or glibc versions where a
+system call or library function appeared,
+or changed significantly in its operation.
+.IP
+As a general rule, every new interface should
+include a HISTORY section in its manual page.
+Unfortunately,
+many existing manual pages don't include this information
+(since there was no policy to do so when they were written).
+Patches to remedy this are welcome,
+but, from the perspective of programmers writing new code,
+this information probably matters only in the case of kernel
+interfaces that have been added in Linux 2.4 or later
+(i.e., changes since Linux 2.2),
+and library functions that have been added to glibc since glibc 2.1
+(i.e., changes since glibc 2.0).
+.IP
+The
+.BR syscalls (2)
+manual page also provides information about kernel versions
+in which various system calls first appeared.
+.P
+Old versions of standards should be mentioned here,
+rather than in STANDARDS,
+for example,
+SUS, SUSv2, and XPG, or the SVr4 and 4.xBSD implementation standards.
+.TP
+.B NOTES
+Miscellaneous notes.
+.IP
+For Section 2 and 3 man pages you may find it useful to include
+subsections (\fBSS\fP) named \fILinux Notes\fP and \fIglibc Notes\fP.
+.IP
+In Section 2, use the heading
+.I "C library/kernel differences"
+to mark off notes that describe the differences (if any) between
+the C library wrapper function for a system call and
+the raw system call interface provided by the kernel.
+.TP
+.B CAVEATS
+Warnings about typical user misuse of an API,
+that don't constitute an API bug or design defect.
+.TP
+.B BUGS
+A list of limitations, known defects or inconveniences,
+and other questionable activities.
+.TP
+.B EXAMPLES
+One or more examples demonstrating how this function, file, or
+command is used.
+.IP
+For details on writing example programs,
+see \fIExample programs\fP below.
+.TP
+.B AUTHORS
+A list of authors of the documentation or program.
+.IP
+\fBUse of an AUTHORS section is strongly discouraged\fP.
+Generally, it is better not to clutter every page with a list
+of (over time potentially numerous) authors;
+if you write or significantly amend a page,
+add a copyright notice as a comment in the source file.
+If you are the author of a device driver and want to include
+an address for reporting bugs, place this under the BUGS section.
+.TP
+.B REPORTING BUGS
+The
+.I man-pages
+project doesn't use a REPORTING BUGS section in manual pages.
+Information on reporting bugs is instead supplied in the
+script-generated COLOPHON section.
+However, various projects do use a REPORTING BUGS section.
+It is recommended to place it near the foot of the page.
+.TP
+.B COPYRIGHT
+The
+.I man-pages
+project doesn't use a COPYRIGHT section in manual pages.
+Copyright information is instead maintained in the page source.
+In pages where this section is present,
+it is recommended to place it near the foot of the page, just above SEE ALSO.
+.TP
+.B SEE ALSO
+A comma-separated list of related man pages, possibly followed by
+other related pages or documents.
+.IP
+The list should be ordered by section number and
+then alphabetically by name.
+Do not terminate this list with a period.
+.IP
+Where the SEE ALSO list contains many long manual page names,
+to improve the visual result of the output, it may be useful to employ the
+.I .ad l
+(don't right justify)
+and
+.I .nh
+(don't hyphenate)
+directives.
+Hyphenation of individual page names can be prevented
+by preceding words with the string "\e%".
+.IP
+Given the distributed, autonomous nature of FOSS projects
+and their documentation, it is sometimes necessary\[em]and in many cases
+desirable\[em]that the SEE ALSO section includes references to
+manual pages provided by other projects.
+.SH FORMATTING AND WORDING CONVENTIONS
+The following subsections note some details for preferred formatting and
+wording conventions in various sections of the pages in the
+.I man-pages
+project.
+.SS SYNOPSIS
+Wrap the function prototype(s) in a
+.IR .nf / .fi
+pair to prevent filling.
+.P
+In general, where more than one function prototype is shown in the SYNOPSIS,
+the prototypes should
+.I not
+be separated by blank lines.
+However, blank lines (achieved using
+.IR .P )
+may be added in the following cases:
+.IP \[bu] 3
+to separate long lists of function prototypes into related groups
+(see for example
+.BR list (3));
+.IP \[bu]
+in other cases that may improve readability.
+.P
+In the SYNOPSIS, a long function prototype may need to be
+continued over to the next line.
+The continuation line is indented according to the following rules:
+.IP (1) 5
+If there is a single such prototype that needs to be continued,
+then align the continuation line so that when the page is
+rendered on a fixed-width font device (e.g., on an xterm) the
+continuation line starts just below the start of the argument
+list in the line above.
+(Exception: the indentation may be
+adjusted if necessary to prevent a very long continuation line
+or a further continuation line where the function prototype is
+very long.)
+As an example:
+.IP
+.in +4n
+.nf
+.BI "int tcsetattr(int " fd ", int " optional_actions ,
+.BI "              const struct termios *" termios_p );
+.fi
+.in
+.IP (2)
+But, where multiple functions in the SYNOPSIS require
+continuation lines, and the function names have different
+lengths, then align all continuation lines to start in the
+same column.
+This provides a nicer rendering in PDF output
+(because the SYNOPSIS uses a variable width font where
+spaces render narrower than most characters).
+As an example:
+.IP
+.in +4n
+.nf
+.BI "int getopt(int " argc ", char * const " argv[] ,
+.BI "           const char *" optstring );
+.BI "int getopt_long(int " argc ", char * const " argv[] ,
+.BI "           const char *" optstring ,
+.BI "           const struct option *" longopts ", int *" longindex );
+.fi
+.in
+.SS RETURN VALUE
+The preferred wording to describe how
+.I errno
+is set is
+.RI \[dq] errno
+is set to indicate the error"
+or similar.
+.\" Before man-pages 5.11, many different wordings were used, which
+.\" was confusing, and potentially made scripted edits more difficult.
+This wording is consistent with the wording used in both POSIX.1 and FreeBSD.
+.SS ATTRIBUTES
+.\" See man-pages commit c466875ecd64ed3d3cd3e578406851b7dfb397bf
+Note the following:
+.IP \[bu] 3
+Wrap the table in this section in a
+.IR ".ad\ l" / .ad
+pair to disable text filling and a
+.IR .nh / .hy
+pair to disable hyphenation.
+.IP \[bu]
+Ensure that the table occupies the full page width through the use of an
+.I lbx
+description for one of the columns
+(usually the first column,
+though in some cases the last column if it contains a lot of text).
+.IP \[bu]
+Make free use of
+.IR T{ / T}
+macro pairs to allow table cells to be broken over multiple lines
+(also bearing in mind that pages may sometimes be rendered to a
+width of less than 80 columns).
+.P
+For examples of all of the above, see the source code of various pages.
+.SH STYLE GUIDE
+The following subsections describe the preferred style for the
+.I man-pages
+project.
+For details not covered below, the Chicago Manual of Style
+is usually a good source;
+try also grepping for preexisting usage in the project source tree.
+.SS Use of gender-neutral language
+As far as possible, use gender-neutral language in the text of man
+pages.
+Use of "they" ("them", "themself", "their") as a gender-neutral singular
+pronoun is acceptable.
+.\"
+.SS Formatting conventions for manual pages describing commands
+For manual pages that describe a command (typically in Sections 1 and 8),
+the arguments are always specified using italics,
+.IR "even in the SYNOPSIS section" .
+.P
+The name of the command, and its options, should
+always be formatted in bold.
+.\"
+.SS Formatting conventions for manual pages describing functions
+For manual pages that describe functions (typically in Sections 2 and 3),
+the arguments are always specified using italics,
+.IR "even in the SYNOPSIS section" ,
+where the rest of the function is specified in bold:
+.P
+.BI "    int myfunction(int " argc ", char **" argv );
+.P
+Variable names should, like argument names, be specified in italics.
+.P
+Any reference to the subject of the current manual page
+should be written with the name in bold followed by
+a pair of parentheses in Roman (normal) font.
+For example, in the
+.BR fcntl (2)
+man page, references to the subject of the page would be written as:
+.BR fcntl ().
+The preferred way to write this in the source file is:
+.P
+.EX
+    .BR fcntl ()
+.EE
+.P
+(Using this format, rather than the use of "\efB...\efP()"
+makes it easier to write tools that parse man page source files.)
+.\"
+.SS Use semantic newlines
+In the source of a manual page,
+new sentences should be started on new lines,
+long sentences should be split into lines at clause breaks
+(commas, semicolons, colons, and so on),
+and long clauses should be split at phrase boundaries.
+This convention, sometimes known as "semantic newlines",
+makes it easier to see the effect of patches,
+which often operate at the level of
+individual sentences, clauses, or phrases.
+.\"
+.SS Lists
+There are different kinds of lists:
+.TP
+Tagged paragraphs
+These are used for a list of tags and their descriptions.
+When the tags are constants (either macros or numbers)
+they are in bold.
+Use the
+.B .TP
+macro.
+.IP
+An example is this "Tagged paragraphs" subsection is itself.
+.TP
+Ordered lists
+Elements are preceded by a number in parentheses (1), (2).
+These represent a set of steps that have an order.
+.IP
+When there are substeps,
+they will be numbered like (4.2).
+.TP
+Positional lists
+Elements are preceded by a number (index) in square brackets [4], [5].
+These represent fields in a set.
+The first index will be:
+.RS
+.TP
+.B 0
+When it represents fields of a C data structure,
+to be consistent with arrays.
+.PD 0
+.TP
+.B 1
+When it represents fields of a file,
+to be consistent with tools like
+.BR cut (1).
+.PD
+.RE
+.TP
+Alternatives list
+Elements are preceded by a letter in parentheses (a), (b).
+These represent a set of (normally) exclusive alternatives.
+.TP
+Bullet lists
+Elements are preceded by bullet symbols
+.RB ( \e[bu] ).
+Anything that doesn't fit elsewhere is
+usually covered by this type of list.
+.TP
+Numbered notes
+Not really a list,
+but the syntax is identical to "positional lists".
+.P
+There should always be exactly
+2 spaces between the list symbol and the elements.
+This doesn't apply to "tagged paragraphs",
+which use the default indentation rules.
+.\"
+.SS Formatting conventions (general)
+Paragraphs should be separated by suitable markers (usually either
+.I .P
+or
+.IR .IP ).
+Do
+.I not
+separate paragraphs using blank lines, as this results in poor rendering
+in some output formats (such as PostScript and PDF).
+.P
+Filenames (whether pathnames, or references to header files)
+are always in italics (e.g.,
+.IR <stdio.h> ),
+except in the SYNOPSIS section, where included files are in bold (e.g.,
+.BR "#include <stdio.h>" ).
+When referring to a standard header file include,
+specify the header file surrounded by angle brackets,
+in the usual C way (e.g.,
+.IR <stdio.h> ).
+.P
+Special macros, which are usually in uppercase, are in bold (e.g.,
+.BR MAXINT ).
+Exception: don't boldface NULL.
+.P
+When enumerating a list of error codes, the codes are in bold (this list
+usually uses the
+.B \&.TP
+macro).
+.P
+Complete commands should, if long,
+be written as an indented line on their own,
+with a blank line before and after the command, for example
+.P
+.in +4n
+.EX
+man 7 man\-pages
+.EE
+.in
+.P
+If the command is short, then it can be included inline in the text,
+in italic format, for example,
+.IR "man 7 man-pages" .
+In this case, it may be worth using nonbreaking spaces
+(\e[ti]) at suitable places in the command.
+Command options should be written in italics (e.g.,
+.IR \-l ).
+.P
+Expressions, if not written on a separate indented line, should
+be specified in italics.
+Again, the use of nonbreaking spaces may be appropriate
+if the expression is inlined with normal text.
+.P
+When showing example shell sessions,
+user input should be formatted in bold,
+for example
+.P
+.in +4n
+.EX
+$ \fBdate\fP
+Thu Jul  7 13:01:27 CEST 2016
+.EE
+.in
+.P
+Any reference to another man page
+should be written with the name in bold,
+.I always
+followed by the section number,
+formatted in Roman (normal) font, without any
+separating spaces (e.g.,
+.BR intro (2)).
+The preferred way to write this in the source file is:
+.P
+.EX
+    .BR intro (2)
+.EE
+.P
+(Including the section number in cross references lets tools like
+.BR man2html (1)
+create properly hyperlinked pages.)
+.P
+Control characters should be written in bold face,
+with no quotes; for example,
+.BR \[ha]X .
+.SS Spelling
+Starting with release 2.59,
+.I man-pages
+follows American spelling conventions
+(previously, there was a random mix of British and American spellings);
+please write all new pages and patches according to these conventions.
+.P
+Aside from the well-known spelling differences,
+there are a few other subtleties to watch for:
+.IP \[bu] 3
+American English tends to use the forms "backward", "upward", "toward",
+and so on
+rather than the British forms "backwards", "upwards", "towards", and so on.
+.IP \[bu]
+Opinions are divided on "acknowledgement" vs "acknowledgment".
+The latter is predominant, but not universal usage in American English.
+POSIX and the BSD license use the former spelling.
+In the Linux man-pages project, we use "acknowledgement".
+.SS BSD version numbers
+The classical scheme for writing BSD version numbers is
+.IR x.yBSD ,
+where
+.I x.y
+is the version number (e.g., 4.2BSD).
+Avoid forms such as
+.IR "BSD 4.3" .
+.SS Capitalization
+In subsection ("SS") headings,
+capitalize the first word in the heading, but otherwise use lowercase,
+except where English usage (e.g., proper nouns) or programming
+language requirements (e.g., identifier names) dictate otherwise.
+For example:
+.P
+.in +4n
+.EX
+\&.SS Unicode under Linux
+.EE
+.in
+.\"
+.SS Indentation of structure definitions, shell session logs, and so on
+When structure definitions, shell session logs, and so on are included
+in running text, indent them by 4 spaces (i.e., a block enclosed by
+.I ".in\ +4n"
+and
+.IR ".in" ),
+format them using the
+.I .EX
+and
+.I .EE
+macros, and surround them with suitable paragraph markers (either
+.I .P
+or
+.IR .IP ).
+For example:
+.P
+.in +4n
+.EX
+\&.P
+\&.in +4n
+\&.EX
+int
+main(int argc, char *argv[])
+{
+    return 0;
+}
+\&.EE
+\&.in
+\&.P
+.EE
+.in
+.SS Preferred terms
+The following table lists some preferred terms to use in man pages,
+mainly to ensure consistency across pages.
+.ad l
+.TS
+l l l
+---
+l l ll.
+Term	Avoid using	Notes
+
+bit mask	bitmask
+built-in	builtin
+Epoch	epoch	T{
+For the UNIX Epoch (00:00:00, 1 Jan 1970 UTC)
+T}
+filename	file name
+filesystem	file system
+hostname	host name
+inode	i-node
+lowercase	lower case, lower-case
+nonzero	non-zero
+pathname	path name
+pseudoterminal	pseudo-terminal
+privileged port	T{
+reserved port,
+system port
+T}
+real-time	T{
+realtime,
+real time
+T}
+run time	runtime
+saved set-group-ID	T{
+saved group ID,
+saved set-GID
+T}
+saved set-user-ID	T{
+saved user ID,
+saved set-UID
+T}
+set-group-ID	set-GID, setgid
+set-user-ID	set-UID, setuid
+superuser	T{
+super user,
+super-user
+T}
+superblock	T{
+super block,
+super-block
+T}
+symbolic link	symlink
+timestamp	time stamp
+timezone	time zone
+uppercase	upper case, upper-case
+usable	useable
+user space	userspace
+username	user name
+x86-64	x86_64	T{
+Except if referring to result of "uname\ \-m" or similar
+T}
+zeros	zeroes
+.TE
+.P
+See also the discussion
+.I Hyphenation of attributive compounds
+below.
+.SS Terms to avoid
+The following table lists some terms to avoid using in man pages,
+along with some suggested alternatives,
+mainly to ensure consistency across pages.
+.ad l
+.TS
+l l l
+---
+l l l.
+Avoid	Use instead	Notes
+
+32bit	32-bit	T{
+same for 8-bit, 16-bit, etc.
+T}
+current process	calling process	T{
+A common mistake made by kernel programmers when writing man pages
+T}
+manpage	T{
+man page, manual page
+T}
+minus infinity	negative infinity
+non-root	unprivileged user
+non-superuser	unprivileged user
+nonprivileged	unprivileged
+OS	operating system
+plus infinity	positive infinity
+pty	pseudoterminal
+tty	terminal
+Unices	UNIX systems
+Unixes	UNIX systems
+.TE
+.ad
+.\"
+.SS Trademarks
+Use the correct spelling and case for trademarks.
+The following is a list of the correct spellings of various
+relevant trademarks that are sometimes misspelled:
+.IP
+.TS
+l.
+DG/UX
+HP-UX
+UNIX
+UnixWare
+.TE
+.SS NULL, NUL, null pointer, and null byte
+A
+.I null pointer
+is a pointer that points to nothing,
+and is normally indicated by the constant
+.IR NULL .
+On the other hand,
+.I NUL
+is the
+.IR "null byte" ,
+a byte with the value 0, represented in C via the character constant
+.IR \[aq]\e0\[aq] .
+.P
+The preferred term for the pointer is "null pointer" or simply "NULL";
+avoid writing "NULL pointer".
+.P
+The preferred term for the byte is "null byte".
+Avoid writing "NUL", since it is too easily confused with "NULL".
+Avoid also the terms "zero byte" and "null character".
+The byte that terminates a C string should be described
+as "the terminating null byte";
+strings may be described as "null-terminated",
+but avoid the use of "NUL-terminated".
+.SS Hyperlinks
+For hyperlinks, use the
+.IR .UR / .UE
+macro pair
+(see
+.BR groff_man (7)).
+This produces proper hyperlinks that can be used in a web browser,
+when rendering a page with, say:
+.P
+.in +4n
+.EX
+BROWSER=firefox man -H pagename
+.EE
+.in
+.SS Use of e.g., i.e., etc., a.k.a., and similar
+In general, the use of abbreviations such as "e.g.", "i.e.", "etc.",
+"cf.", and "a.k.a." should be avoided,
+in favor of suitable full wordings
+("for example", "that is", "and so on", "compare to", "also known as").
+.P
+The only place where such abbreviations may be acceptable is in
+.I short
+parenthetical asides (e.g., like this one).
+.P
+Always include periods in such abbreviations, as shown here.
+In addition, "e.g." and "i.e." should always be followed by a comma.
+.SS Em-dashes
+The way to write an em-dash\[em]the glyph that appears
+at either end of this subphrase\[em]in *roff is with the macro "\e[em]".
+(On an ASCII terminal, an em-dash typically renders as two hyphens,
+but in other typographical contexts it renders as a long dash.)
+Em-dashes should be written
+.I without
+surrounding spaces.
+.SS Hyphenation of attributive compounds
+Compound terms should be hyphenated when used attributively
+(i.e., to qualify a following noun). Some examples:
+.IP
+.TS
+l.
+32-bit value
+command-line argument
+floating-point number
+run-time check
+user-space function
+wide-character string
+.TE
+.SS Hyphenation with multi, non, pre, re, sub, and so on
+The general tendency in modern English is not to hyphenate
+after prefixes such as "multi", "non", "pre", "re", "sub", and so on.
+Manual pages should generally follow this rule when these prefixes are
+used in natural English constructions with simple suffixes.
+The following list gives some examples of the preferred forms:
+.IP
+.TS
+l.
+interprocess
+multithreaded
+multiprocess
+nonblocking
+nondefault
+nonempty
+noninteractive
+nonnegative
+nonportable
+nonzero
+preallocated
+precreate
+prerecorded
+reestablished
+reinitialize
+rearm
+reread
+subcomponent
+subdirectory
+subsystem
+.TE
+.P
+Hyphens should be retained when the prefixes are used in nonstandard
+English words, with trademarks, proper nouns, acronyms, or compound terms.
+Some examples:
+.IP
+.TS
+l.
+non-ASCII
+non-English
+non-NULL
+non-real-time
+.TE
+.P
+Finally, note that "re-create" and "recreate" are two different verbs,
+and the former is probably what you want.
+.\"
+.SS Generating optimal glyphs
+Where a real minus character is required (e.g., for numbers such as \-1,
+for man page cross references such as
+.BR utf\-8 (7),
+or when writing options that have a leading dash, such as in
+.IR "ls\ \-l"),
+use the following form in the man page source:
+.P
+.in +4n
+.EX
+\e\-
+.EE
+.in
+.P
+This guideline applies also to code examples.
+.P
+The use of real minus signs serves the following purposes:
+.\" https://lore.kernel.org/linux-man/20210121061158.5ul7226fgbrmodbt@localhost.localdomain/
+.IP \[bu] 3
+To provide better renderings on various targets other than
+ASCII terminals,
+notably in PDF and on Unicode/UTF\-8-capable terminals.
+.IP \[bu]
+To generate glyphs that when copied from rendered pages will
+produce real minus signs when pasted into a terminal.
+.P
+To produce unslanted single quotes that render well in ASCII, UTF-8, and PDF,
+use "\e[aq]" ("apostrophe quote"); for example
+.P
+.in +4n
+.EX
+\e[aq]C\e[aq]
+.EE
+.in
+.P
+where
+.I C
+is the quoted character.
+This guideline applies also to character constants used in code examples.
+.P
+Where a proper caret (\[ha]) that renders well in both a terminal and PDF
+is required, use "\\[ha]".
+This is especially necessary in code samples,
+to get a nicely rendered caret when rendering to PDF.
+.P
+Using a naked "\[ti]" character results in a poor rendering in PDF.
+Instead use "\\[ti]".
+This is especially necessary in code samples,
+to get a nicely rendered tilde when rendering to PDF.
+.\"
+.SS Example programs and shell sessions
+Manual pages may include example programs demonstrating how to
+use a system call or library function.
+However, note the following:
+.IP \[bu] 3
+Example programs should be written in C.
+.IP \[bu]
+An example program is necessary and useful only if it demonstrates
+something beyond what can easily be provided in a textual
+description of the interface.
+An example program that does nothing
+other than call an interface usually serves little purpose.
+.IP \[bu]
+Example programs should ideally be short
+(e.g., a good example can often be provided in less than 100 lines of code),
+though in some cases longer programs may be necessary
+to properly illustrate the use of an API.
+.IP \[bu]
+Expressive code is appreciated.
+.IP \[bu]
+Comments should included where helpful.
+Complete sentences in free-standing comments should be
+terminated by a period.
+Periods should generally be omitted in "tag" comments
+(i.e., comments that are placed on the same line of code);
+such comments are in any case typically brief phrases
+rather than complete sentences.
+.IP \[bu]
+Example programs should do error checking after system calls and
+library function calls.
+.IP \[bu]
+Example programs should be complete, and compile without
+warnings when compiled with \fIcc\ \-Wall\fP.
+.IP \[bu]
+Where possible and appropriate, example programs should allow
+experimentation, by varying their behavior based on inputs
+(ideally from command-line arguments, or alternatively, via
+input read by the program).
+.IP \[bu]
+Example programs should be laid out according to Kernighan and
+Ritchie style, with 4-space indents.
+(Avoid the use of TAB characters in source code!)
+The following command can be used to format your source code to
+something close to the preferred style:
+.IP
+.in +4n
+.EX
+indent \-npro \-kr \-i4 \-ts4 \-sob \-l72 \-ss \-nut \-psl prog.c
+.EE
+.in
+.IP \[bu]
+For consistency, all example programs should terminate using either of:
+.IP
+.in +4n
+.EX
+exit(EXIT_SUCCESS);
+exit(EXIT_FAILURE);
+.EE
+.in
+.IP
+Avoid using the following forms to terminate a program:
+.IP
+.in +4n
+.EX
+exit(0);
+exit(1);
+return n;
+.EE
+.in
+.IP \[bu]
+If there is extensive explanatory text before the
+program source code, mark off the source code
+with a subsection heading
+.IR "Program source" ,
+as in:
+.IP
+.in +4n
+.EX
+\&.SS Program source
+.EE
+.in
+.IP
+Always do this if the explanatory text includes a shell session log.
+.P
+If you include a shell session log demonstrating the use of a program
+or other system feature:
+.IP \[bu] 3
+Place the session log above the source code listing.
+.IP \[bu]
+Indent the session log by four spaces.
+.IP \[bu]
+Boldface the user input text,
+to distinguish it from output produced by the system.
+.P
+For some examples of what example programs should look like, see
+.BR wait (2)
+and
+.BR pipe (2).
+.SH EXAMPLES
+For canonical examples of how man pages in the
+.I man-pages
+package should look, see
+.BR pipe (2)
+and
+.BR fcntl (2).
+.SH SEE ALSO
+.BR man (1),
+.BR man2html (1),
+.BR attributes (7),
+.BR groff (7),
+.BR groff_man (7),
+.BR man (7),
+.BR mdoc (7)
diff --git a/man/man7/man.7 b/man/man7/man.7
new file mode 100644
index 000000000..f460f4ad3
--- /dev/null
+++ b/man/man7/man.7
@@ -0,0 +1 @@
+.so man7/groff_man.7
diff --git a/man/man7/math_error.7 b/man/man7/math_error.7
new file mode 100644
index 000000000..46e90a06f
--- /dev/null
+++ b/man/man7/math_error.7
@@ -0,0 +1,246 @@
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH math_error 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+math_error \- detecting errors from mathematical functions
+.SH SYNOPSIS
+.nf
+.B #include <math.h>
+.B #include <errno.h>
+.B #include <fenv.h>
+.fi
+.SH DESCRIPTION
+When an error occurs,
+most library functions indicate this fact by returning a special value
+(e.g., \-1 or NULL).
+Because they typically return a floating-point number,
+the mathematical functions declared in
+.I <math.h>
+indicate an error using other mechanisms.
+There are two error-reporting mechanisms:
+the older one sets
+.IR errno ;
+the newer one uses the floating-point exception mechanism (the use of
+.BR feclearexcept (3)
+and
+.BR fetestexcept (3),
+as outlined below)
+described in
+.BR fenv (3).
+.P
+A portable program that needs to check for an error from a mathematical
+function should set
+.I errno
+to zero, and make the following call
+.P
+.in +4n
+.EX
+feclearexcept(FE_ALL_EXCEPT);
+.EE
+.in
+.P
+before calling a mathematical function.
+.P
+Upon return from the mathematical function, if
+.I errno
+is nonzero, or the following call (see
+.BR fenv (3))
+returns nonzero
+.P
+.in +4n
+.EX
+fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
+             FE_UNDERFLOW);
+.EE
+.in
+.P
+.\" enum
+.\" {
+.\" FE_INVALID = 0x01,
+.\" __FE_DENORM = 0x02,
+.\" FE_DIVBYZERO = 0x04,
+.\" FE_OVERFLOW = 0x08,
+.\" FE_UNDERFLOW = 0x10,
+.\" FE_INEXACT = 0x20
+.\" };
+then an error occurred in the mathematical function.
+.P
+The error conditions that can occur for mathematical functions
+are described below.
+.SS Domain error
+A
+.I domain error
+occurs when a mathematical function is supplied with an argument whose
+value falls outside the domain for which the function
+is defined (e.g., giving a negative argument to
+.BR log (3)).
+When a domain error occurs,
+math functions commonly return a NaN
+(though some functions return a different value in this case);
+.I errno
+is set to
+.BR EDOM ,
+and an "invalid"
+.RB ( FE_INVALID )
+floating-point exception is raised.
+.SS Pole error
+A
+.I pole error
+occurs when the mathematical result of a function is an exact infinity
+(e.g., the logarithm of 0 is negative infinity).
+When a pole error occurs,
+the function returns the (signed) value
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+depending on whether the function result type is
+.IR double ,
+.IR float ,
+or
+.IR "long double" .
+The sign of the result is that which is mathematically correct for
+the function.
+.I errno
+is set to
+.BR ERANGE ,
+and a "divide-by-zero"
+.RB ( FE_DIVBYZERO )
+floating-point exception is raised.
+.SS Range error
+A
+.I range error
+occurs when the magnitude of the function result means that it
+cannot be represented in the result type of the function.
+The return value of the function depends on whether the range error
+was an overflow or an underflow.
+.P
+A floating result
+.I overflows
+if the result is finite,
+but is too large to represented in the result type.
+When an overflow occurs,
+the function returns the value
+.BR HUGE_VAL ,
+.BR HUGE_VALF ,
+or
+.BR HUGE_VALL ,
+depending on whether the function result type is
+.IR double ,
+.IR float ,
+or
+.IR "long double" .
+.I errno
+is set to
+.BR ERANGE ,
+and an "overflow"
+.RB ( FE_OVERFLOW )
+floating-point exception is raised.
+.P
+A floating result
+.I underflows
+if the result is too small to be represented in the result type.
+If an underflow occurs,
+a mathematical function typically returns 0.0
+(C99 says a function shall return "an implementation-defined value
+whose magnitude is no greater than the smallest normalized
+positive number in the specified type").
+.I errno
+may be set to
+.BR ERANGE ,
+and an "underflow"
+.RB ( FE_UNDERFLOW )
+floating-point exception may be raised.
+.P
+Some functions deliver a range error if the supplied argument value,
+or the correct function result, would be
+.IR subnormal .
+A subnormal value is one that is nonzero,
+but with a magnitude that is so small that
+it can't be presented in normalized form
+(i.e., with a 1 in the most significant bit of the significand).
+The representation of a subnormal number will contain one
+or more leading zeros in the significand.
+.SH NOTES
+The
+.I math_errhandling
+identifier specified by C99 and POSIX.1 is not supported by glibc.
+.\" See CONFORMANCE in the glibc 2.8 (and earlier) source.
+This identifier is supposed to indicate which of the two
+error-notification mechanisms
+.RI ( errno ,
+exceptions retrievable via
+.BR fetestexcept (3))
+is in use.
+The standards require that at least one be in use,
+but permit both to be available.
+The current (glibc 2.8) situation under glibc is messy.
+Most (but not all) functions raise exceptions on errors.
+Some also set
+.IR errno .
+A few functions set
+.IR errno ,
+but don't raise an exception.
+A very few functions do neither.
+See the individual manual pages for details.
+.P
+To avoid the complexities of using
+.I errno
+and
+.BR fetestexcept (3)
+for error checking,
+it is often advised that one should instead check for bad argument
+values before each call.
+.\" http://www.securecoding.cert.org/confluence/display/seccode/FLP32-C.+Prevent+or+detect+domain+and+range+errors+in+math+functions
+For example, the following code ensures that
+.BR log (3)'s
+argument is not a NaN and is not zero (a pole error) or
+less than zero (a domain error):
+.P
+.in +4n
+.EX
+double x, r;
+\&
+if (isnan(x) || islessequal(x, 0)) {
+    /* Deal with NaN / pole error / domain error */
+}
+\&
+r = log(x);
+.EE
+.in
+.P
+The discussion on this page does not apply to the complex
+mathematical functions (i.e., those declared by
+.IR <complex.h> ),
+which in general are not required to return errors by C99
+and POSIX.1.
+.P
+The
+.BR gcc (1)
+.I "\-fno\-math\-errno"
+option causes the executable to employ implementations of some
+mathematical functions that are faster than the standard
+implementations, but do not set
+.I errno
+on error.
+(The
+.BR gcc (1)
+.I "\-ffast\-math"
+option also enables
+.IR "\-fno\-math\-errno" .)
+An error can still be tested for using
+.BR fetestexcept (3).
+.SH SEE ALSO
+.BR gcc (1),
+.BR errno (3),
+.BR fenv (3),
+.BR fpclassify (3),
+.BR INFINITY (3),
+.BR isgreater (3),
+.BR matherr (3),
+.BR nan (3)
+.P
+.I "info libc"
diff --git a/man/man7/mount_namespaces.7 b/man/man7/mount_namespaces.7
new file mode 100644
index 000000000..1f0a1b41f
--- /dev/null
+++ b/man/man7/mount_namespaces.7
@@ -0,0 +1,1371 @@
+'\" t
+.\" Copyright (c) 2016, 2019, 2021 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH mount_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mount_namespaces \- overview of Linux mount namespaces
+.SH DESCRIPTION
+For an overview of namespaces, see
+.BR namespaces (7).
+.P
+Mount namespaces provide isolation of the list of mounts seen
+by the processes in each namespace instance.
+Thus, the processes in each of the mount namespace instances
+will see distinct single-directory hierarchies.
+.P
+The views provided by the
+.IR /proc/ pid /mounts ,
+.IR /proc/ pid /mountinfo ,
+and
+.IR /proc/ pid /mountstats
+files (all described in
+.BR proc (5))
+correspond to the mount namespace in which the process with the PID
+.I pid
+resides.
+(All of the processes that reside in the same mount namespace
+will see the same view in these files.)
+.P
+A new mount namespace is created using either
+.BR clone (2)
+or
+.BR unshare (2)
+with the
+.B CLONE_NEWNS
+flag.
+When a new mount namespace is created,
+its mount list is initialized as follows:
+.IP \[bu] 3
+If the namespace is created using
+.BR clone (2),
+the mount list of the child's namespace is a copy
+of the mount list in the parent process's mount namespace.
+.IP \[bu]
+If the namespace is created using
+.BR unshare (2),
+the mount list of the new namespace is a copy of
+the mount list in the caller's previous mount namespace.
+.P
+Subsequent modifications to the mount list
+.RB ( mount (2)
+and
+.BR umount (2))
+in either mount namespace will not (by default) affect the
+mount list seen in the other namespace
+(but see the following discussion of shared subtrees).
+.\"
+.SH SHARED SUBTREES
+After the implementation of mount namespaces was completed,
+experience showed that the isolation that they provided was,
+in some cases, too great.
+For example, in order to make a newly loaded optical disk
+available in all mount namespaces,
+a mount operation was required in each namespace.
+For this use case, and others,
+the shared subtree feature was introduced in Linux 2.6.15.
+This feature allows for automatic, controlled propagation of
+.BR mount (2)
+and
+.BR umount (2)
+.I events
+between namespaces
+(or, more precisely, between the mounts that are members of a
+.I peer group
+that are propagating events to one another).
+.P
+Each mount is marked (via
+.BR mount (2))
+as having one of the following
+.IR "propagation types" :
+.TP
+.B MS_SHARED
+This mount shares events with members of a peer group.
+.BR mount (2)
+and
+.BR umount (2)
+events immediately under this mount will propagate
+to the other mounts that are members of the peer group.
+.I Propagation
+here means that the same
+.BR mount (2)
+or
+.BR umount (2)
+will automatically occur
+under all of the other mounts in the peer group.
+Conversely,
+.BR mount (2)
+and
+.BR umount (2)
+events that take place under
+peer mounts will propagate to this mount.
+.TP
+.B MS_PRIVATE
+This mount is private; it does not have a peer group.
+.BR mount (2)
+and
+.BR umount (2)
+events do not propagate into or out of this mount.
+.TP
+.B MS_SLAVE
+.BR mount (2)
+and
+.BR umount (2)
+events propagate into this mount from
+a (master) shared peer group.
+.BR mount (2)
+and
+.BR umount (2)
+events under this mount do not propagate to any peer.
+.IP
+Note that a mount can be the slave of another peer group
+while at the same time sharing
+.BR mount (2)
+and
+.BR umount (2)
+events
+with a peer group of which it is a member.
+(More precisely, one peer group can be the slave of another peer group.)
+.TP
+.B MS_UNBINDABLE
+This is like a private mount,
+and in addition this mount can't be bind mounted.
+Attempts to bind mount this mount
+.RB ( mount (2)
+with the
+.B MS_BIND
+flag) will fail.
+.IP
+When a recursive bind mount
+.RB ( mount (2)
+with the
+.B MS_BIND
+and
+.B MS_REC
+flags) is performed on a directory subtree,
+any bind mounts within the subtree are automatically pruned
+(i.e., not replicated)
+when replicating that subtree to produce the target subtree.
+.P
+For a discussion of the propagation type assigned to a new mount,
+see NOTES.
+.P
+The propagation type is a per-mount-point setting;
+some mounts may be marked as shared
+(with each shared mount being a member of a distinct peer group),
+while others are private
+(or slaved or unbindable).
+.P
+Note that a mount's propagation type determines whether
+.BR mount (2)
+and
+.BR umount (2)
+of mounts
+.I immediately under
+the mount are propagated.
+Thus, the propagation type does not affect propagation of events for
+grandchildren and further removed descendant mounts.
+What happens if the mount itself is unmounted is determined by
+the propagation type that is in effect for the
+.I parent
+of the mount.
+.P
+Members are added to a
+.I peer group
+when a mount is marked as shared and either:
+.IP (a) 5
+the mount is replicated during the creation of a new mount namespace; or
+.IP (b)
+a new bind mount is created from the mount.
+.P
+In both of these cases, the new mount joins the peer group
+of which the existing mount is a member.
+.P
+A new peer group is also created when a child mount is created under
+an existing mount that is marked as shared.
+In this case, the new child mount is also marked as shared and
+the resulting peer group consists of all the mounts
+that are replicated under the peers of parent mounts.
+.P
+A mount ceases to be a member of a peer group when either
+the mount is explicitly unmounted,
+or when the mount is implicitly unmounted because a mount namespace is removed
+(because it has no more member processes).
+.P
+The propagation type of the mounts in a mount namespace
+can be discovered via the "optional fields" exposed in
+.IR /proc/ pid /mountinfo .
+(See
+.BR proc (5)
+for details of this file.)
+The following tags can appear in the optional fields
+for a record in that file:
+.TP
+.I shared:X
+This mount is shared in peer group
+.IR X .
+Each peer group has a unique ID that is automatically
+generated by the kernel,
+and all mounts in the same peer group will show the same ID.
+(These IDs are assigned starting from the value 1,
+and may be recycled when a peer group ceases to have any members.)
+.TP
+.I master:X
+This mount is a slave to shared peer group
+.IR X .
+.TP
+.IR propagate_from:X " (since Linux 2.6.26)"
+.\" commit 97e7e0f71d6d948c25f11f0a33878d9356d9579e
+This mount is a slave and receives propagation from shared peer group
+.IR X .
+This tag will always appear in conjunction with a
+.I master:X
+tag.
+Here,
+.I X
+is the closest dominant peer group under the process's root directory.
+If
+.I X
+is the immediate master of the mount,
+or if there is no dominant peer group under the same root,
+then only the
+.I master:X
+field is present and not the
+.I propagate_from:X
+field.
+For further details, see below.
+.TP
+.I unbindable
+This is an unbindable mount.
+.P
+If none of the above tags is present, then this is a private mount.
+.SS MS_SHARED and MS_PRIVATE example
+Suppose that on a terminal in the initial mount namespace,
+we mark one mount as shared and another as private,
+and then view the mounts in
+.IR /proc/self/mountinfo :
+.P
+.in +4n
+.EX
+sh1# \fBmount \-\-make\-shared /mntS\fP
+sh1# \fBmount \-\-make\-private /mntP\fP
+sh1# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+77 61 8:17 / /mntS rw,relatime shared:1
+83 61 8:15 / /mntP rw,relatime
+.EE
+.in
+.P
+From the
+.I /proc/self/mountinfo
+output, we see that
+.I /mntS
+is a shared mount in peer group 1, and that
+.I /mntP
+has no optional tags, indicating that it is a private mount.
+The first two fields in each record in this file are the unique
+ID for this mount, and the mount ID of the parent mount.
+We can further inspect this file to see that the parent mount of
+.I /mntS
+and
+.I /mntP
+is the root directory,
+.IR / ,
+which is mounted as private:
+.P
+.in +4n
+.EX
+sh1# \fBcat /proc/self/mountinfo | awk \[aq]$1 == 61\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+61 0 8:2 / / rw,relatime
+.EE
+.in
+.P
+On a second terminal,
+we create a new mount namespace where we run a second shell
+and inspect the mounts:
+.P
+.in +4n
+.EX
+$ \fBPS1=\[aq]sh2# \[aq] sudo unshare \-m \-\-propagation unchanged sh\fP
+sh2# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+222 145 8:17 / /mntS rw,relatime shared:1
+225 145 8:15 / /mntP rw,relatime
+.EE
+.in
+.P
+The new mount namespace received a copy of the initial mount namespace's
+mounts.
+These new mounts maintain the same propagation types,
+but have unique mount IDs.
+(The
+.I \-\-propagation\~unchanged
+option prevents
+.BR unshare (1)
+from marking all mounts as private when creating a new mount namespace,
+.\" Since util-linux 2.27
+which it does by default.)
+.P
+In the second terminal, we then create submounts under each of
+.I /mntS
+and
+.I /mntP
+and inspect the set-up:
+.P
+.in +4n
+.EX
+sh2# \fBmkdir /mntS/a\fP
+sh2# \fBmount /dev/sdb6 /mntS/a\fP
+sh2# \fBmkdir /mntP/b\fP
+sh2# \fBmount /dev/sdb7 /mntP/b\fP
+sh2# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+222 145 8:17 / /mntS rw,relatime shared:1
+225 145 8:15 / /mntP rw,relatime
+178 222 8:22 / /mntS/a rw,relatime shared:2
+230 225 8:23 / /mntP/b rw,relatime
+.EE
+.in
+.P
+From the above, it can be seen that
+.I /mntS/a
+was created as shared (inheriting this setting from its parent mount) and
+.I /mntP/b
+was created as a private mount.
+.P
+Returning to the first terminal and inspecting the set-up,
+we see that the new mount created under the shared mount
+.I /mntS
+propagated to its peer mount (in the initial mount namespace),
+but the new mount created under the private mount
+.I /mntP
+did not propagate:
+.P
+.in +4n
+.EX
+sh1# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+77 61 8:17 / /mntS rw,relatime shared:1
+83 61 8:15 / /mntP rw,relatime
+179 77 8:22 / /mntS/a rw,relatime shared:2
+.EE
+.in
+.\"
+.SS MS_SLAVE example
+Making a mount a slave allows it to receive propagated
+.BR mount (2)
+and
+.BR umount (2)
+events from a master shared peer group,
+while preventing it from propagating events to that master.
+This is useful if we want to (say) receive a mount event when
+an optical disk is mounted in the master shared peer group
+(in another mount namespace),
+but want to prevent
+.BR mount (2)
+and
+.BR umount (2)
+events under the slave mount
+from having side effects in other namespaces.
+.P
+We can demonstrate the effect of slaving by first marking
+two mounts as shared in the initial mount namespace:
+.P
+.in +4n
+.EX
+sh1# \fBmount \-\-make\-shared /mntX\fP
+sh1# \fBmount \-\-make\-shared /mntY\fP
+sh1# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+132 83 8:23 / /mntX rw,relatime shared:1
+133 83 8:22 / /mntY rw,relatime shared:2
+.EE
+.in
+.P
+On a second terminal,
+we create a new mount namespace and inspect the mounts:
+.P
+.in +4n
+.EX
+sh2# \fBunshare \-m \-\-propagation unchanged sh\fP
+sh2# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+168 167 8:23 / /mntX rw,relatime shared:1
+169 167 8:22 / /mntY rw,relatime shared:2
+.EE
+.in
+.P
+In the new mount namespace, we then mark one of the mounts as a slave:
+.P
+.in +4n
+.EX
+sh2# \fBmount \-\-make\-slave /mntY\fP
+sh2# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+168 167 8:23 / /mntX rw,relatime shared:1
+169 167 8:22 / /mntY rw,relatime master:2
+.EE
+.in
+.P
+From the above output, we see that
+.I /mntY
+is now a slave mount that is receiving propagation events from
+the shared peer group with the ID 2.
+.P
+Continuing in the new namespace, we create submounts under each of
+.I /mntX
+and
+.IR /mntY :
+.P
+.in +4n
+.EX
+sh2# \fBmkdir /mntX/a\fP
+sh2# \fBmount /dev/sda3 /mntX/a\fP
+sh2# \fBmkdir /mntY/b\fP
+sh2# \fBmount /dev/sda5 /mntY/b\fP
+.EE
+.in
+.P
+When we inspect the state of the mounts in the new mount namespace,
+we see that
+.I /mntX/a
+was created as a new shared mount
+(inheriting the "shared" setting from its parent mount) and
+.I /mntY/b
+was created as a private mount:
+.P
+.in +4n
+.EX
+sh2# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+168 167 8:23 / /mntX rw,relatime shared:1
+169 167 8:22 / /mntY rw,relatime master:2
+173 168 8:3 / /mntX/a rw,relatime shared:3
+175 169 8:5 / /mntY/b rw,relatime
+.EE
+.in
+.P
+Returning to the first terminal (in the initial mount namespace),
+we see that the mount
+.I /mntX/a
+propagated to the peer (the shared
+.IR /mntX ),
+but the mount
+.I /mntY/b
+was not propagated:
+.P
+.in +4n
+.EX
+sh1# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+132 83 8:23 / /mntX rw,relatime shared:1
+133 83 8:22 / /mntY rw,relatime shared:2
+174 132 8:3 / /mntX/a rw,relatime shared:3
+.EE
+.in
+.P
+Now we create a new mount under
+.I /mntY
+in the first shell:
+.P
+.in +4n
+.EX
+sh1# \fBmkdir /mntY/c\fP
+sh1# \fBmount /dev/sda1 /mntY/c\fP
+sh1# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+132 83 8:23 / /mntX rw,relatime shared:1
+133 83 8:22 / /mntY rw,relatime shared:2
+174 132 8:3 / /mntX/a rw,relatime shared:3
+178 133 8:1 / /mntY/c rw,relatime shared:4
+.EE
+.in
+.P
+When we examine the mounts in the second mount namespace,
+we see that in this case the new mount has been propagated
+to the slave mount,
+and that the new mount is itself a slave mount (to peer group 4):
+.P
+.in +4n
+.EX
+sh2# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+168 167 8:23 / /mntX rw,relatime shared:1
+169 167 8:22 / /mntY rw,relatime master:2
+173 168 8:3 / /mntX/a rw,relatime shared:3
+175 169 8:5 / /mntY/b rw,relatime
+179 169 8:1 / /mntY/c rw,relatime master:4
+.EE
+.in
+.\"
+.SS MS_UNBINDABLE example
+One of the primary purposes of unbindable mounts is to avoid
+the "mount explosion" problem when repeatedly performing bind mounts
+of a higher-level subtree at a lower-level mount.
+The problem is illustrated by the following shell session.
+.P
+Suppose we have a system with the following mounts:
+.P
+.in +4n
+.EX
+# \fBmount | awk \[aq]{print $1, $2, $3}\[aq]\fP
+/dev/sda1 on /
+/dev/sdb6 on /mntX
+/dev/sdb7 on /mntY
+.EE
+.in
+.P
+Suppose furthermore that we wish to recursively bind mount
+the root directory under several users' home directories.
+We do this for the first user, and inspect the mounts:
+.P
+.in +4n
+.EX
+# \fBmount \-\-rbind / /home/cecilia/\fP
+# \fBmount | awk \[aq]{print $1, $2, $3}\[aq]\fP
+/dev/sda1 on /
+/dev/sdb6 on /mntX
+/dev/sdb7 on /mntY
+/dev/sda1 on /home/cecilia
+/dev/sdb6 on /home/cecilia/mntX
+/dev/sdb7 on /home/cecilia/mntY
+.EE
+.in
+.P
+When we repeat this operation for the second user,
+we start to see the explosion problem:
+.P
+.in +4n
+.EX
+# \fBmount \-\-rbind / /home/henry\fP
+# \fBmount | awk \[aq]{print $1, $2, $3}\[aq]\fP
+/dev/sda1 on /
+/dev/sdb6 on /mntX
+/dev/sdb7 on /mntY
+/dev/sda1 on /home/cecilia
+/dev/sdb6 on /home/cecilia/mntX
+/dev/sdb7 on /home/cecilia/mntY
+/dev/sda1 on /home/henry
+/dev/sdb6 on /home/henry/mntX
+/dev/sdb7 on /home/henry/mntY
+/dev/sda1 on /home/henry/home/cecilia
+/dev/sdb6 on /home/henry/home/cecilia/mntX
+/dev/sdb7 on /home/henry/home/cecilia/mntY
+.EE
+.in
+.P
+Under
+.IR /home/henry ,
+we have not only recursively added the
+.I /mntX
+and
+.I /mntY
+mounts, but also the recursive mounts of those directories under
+.I /home/cecilia
+that were created in the previous step.
+Upon repeating the step for a third user,
+it becomes obvious that the explosion is exponential in nature:
+.P
+.in +4n
+.EX
+# \fBmount \-\-rbind / /home/otto\fP
+# \fBmount | awk \[aq]{print $1, $2, $3}\[aq]\fP
+/dev/sda1 on /
+/dev/sdb6 on /mntX
+/dev/sdb7 on /mntY
+/dev/sda1 on /home/cecilia
+/dev/sdb6 on /home/cecilia/mntX
+/dev/sdb7 on /home/cecilia/mntY
+/dev/sda1 on /home/henry
+/dev/sdb6 on /home/henry/mntX
+/dev/sdb7 on /home/henry/mntY
+/dev/sda1 on /home/henry/home/cecilia
+/dev/sdb6 on /home/henry/home/cecilia/mntX
+/dev/sdb7 on /home/henry/home/cecilia/mntY
+/dev/sda1 on /home/otto
+/dev/sdb6 on /home/otto/mntX
+/dev/sdb7 on /home/otto/mntY
+/dev/sda1 on /home/otto/home/cecilia
+/dev/sdb6 on /home/otto/home/cecilia/mntX
+/dev/sdb7 on /home/otto/home/cecilia/mntY
+/dev/sda1 on /home/otto/home/henry
+/dev/sdb6 on /home/otto/home/henry/mntX
+/dev/sdb7 on /home/otto/home/henry/mntY
+/dev/sda1 on /home/otto/home/henry/home/cecilia
+/dev/sdb6 on /home/otto/home/henry/home/cecilia/mntX
+/dev/sdb7 on /home/otto/home/henry/home/cecilia/mntY
+.EE
+.in
+.P
+The mount explosion problem in the above scenario can be avoided
+by making each of the new mounts unbindable.
+The effect of doing this is that recursive mounts of the root
+directory will not replicate the unbindable mounts.
+We make such a mount for the first user:
+.P
+.in +4n
+.EX
+# \fBmount \-\-rbind \-\-make\-unbindable / /home/cecilia\fP
+.EE
+.in
+.P
+Before going further, we show that unbindable mounts are indeed unbindable:
+.P
+.in +4n
+.EX
+# \fBmkdir /mntZ\fP
+# \fBmount \-\-bind /home/cecilia /mntZ\fP
+mount: wrong fs type, bad option, bad superblock on /home/cecilia,
+       missing codepage or helper program, or other error
+\&
+       In some cases useful info is found in syslog \- try
+       dmesg | tail or so.
+.EE
+.in
+.P
+Now we create unbindable recursive bind mounts for the other two users:
+.P
+.in +4n
+.EX
+# \fBmount \-\-rbind \-\-make\-unbindable / /home/henry\fP
+# \fBmount \-\-rbind \-\-make\-unbindable / /home/otto\fP
+.EE
+.in
+.P
+Upon examining the list of mounts,
+we see there has been no explosion of mounts,
+because the unbindable mounts were not replicated
+under each user's directory:
+.P
+.in +4n
+.EX
+# \fBmount | awk \[aq]{print $1, $2, $3}\[aq]\fP
+/dev/sda1 on /
+/dev/sdb6 on /mntX
+/dev/sdb7 on /mntY
+/dev/sda1 on /home/cecilia
+/dev/sdb6 on /home/cecilia/mntX
+/dev/sdb7 on /home/cecilia/mntY
+/dev/sda1 on /home/henry
+/dev/sdb6 on /home/henry/mntX
+/dev/sdb7 on /home/henry/mntY
+/dev/sda1 on /home/otto
+/dev/sdb6 on /home/otto/mntX
+/dev/sdb7 on /home/otto/mntY
+.EE
+.in
+.\"
+.SS Propagation type transitions
+The following table shows the effect that applying a new propagation type
+(i.e.,
+.IR mount\~\-\-make\-xxxx )
+has on the existing propagation type of a mount.
+The rows correspond to existing propagation types,
+and the columns are the new propagation settings.
+For reasons of space, "private" is abbreviated as "priv" and
+"unbindable" as "unbind".
+.TS
+lb2 lb2 lb2 lb2 lb1
+lb | l l l l l.
+	make-shared	make-slave	make-priv	make-unbind
+_
+shared	shared	slave/priv [1]	priv	unbind
+slave	slave+shared	slave [2]	priv	unbind
+slave+shared	slave+shared	slave	priv	unbind
+private	shared	priv [2]	priv	unbind
+unbindable	shared	unbind [2]	priv	unbind
+.TE
+.P
+Note the following details to the table:
+.IP [1] 5
+If a shared mount is the only mount in its peer group,
+making it a slave automatically makes it private.
+.IP [2]
+Slaving a nonshared mount has no effect on the mount.
+.\"
+.SS Bind (MS_BIND) semantics
+Suppose that the following command is performed:
+.P
+.in +4n
+.EX
+mount \-\-bind A/a B/b
+.EE
+.in
+.P
+Here,
+.I A
+is the source mount,
+.I B
+is the destination mount,
+.I a
+is a subdirectory path under the mount point
+.IR A ,
+and
+.I b
+is a subdirectory path under the mount point
+.IR B .
+The propagation type of the resulting mount,
+.IR B/b ,
+depends on the propagation types of the mounts
+.I A
+and
+.IR B ,
+and is summarized in the following table.
+.P
+.TS
+lb2 lb1 lb2 lb2 lb2 lb0
+lb2 lb1 lb2 lb2 lb2 lb0
+lb lb | l l l l l.
+			source(A)
+		shared	private	slave	unbind
+_
+dest(B)	shared	shared	shared	slave+shared	invalid
+	nonshared	shared	private	slave	invalid
+.TE
+.P
+Note that a recursive bind of a subtree follows the same semantics
+as for a bind operation on each mount in the subtree.
+(Unbindable mounts are automatically pruned at the target mount point.)
+.P
+For further details, see
+.I Documentation/filesystems/sharedsubtree.rst
+in the kernel source tree.
+.\"
+.SS Move (MS_MOVE) semantics
+Suppose that the following command is performed:
+.P
+.in +4n
+.EX
+mount \-\-move A B/b
+.EE
+.in
+.P
+Here,
+.I A
+is the source mount,
+.I B
+is the destination mount, and
+.I b
+is a subdirectory path under the mount point
+.IR B .
+The propagation type of the resulting mount,
+.IR B/b ,
+depends on the propagation types of the mounts
+.I A
+and
+.IR B ,
+and is summarized in the following table.
+.P
+.TS
+lb2 lb1 lb2 lb2 lb2 lb0
+lb2 lb1 lb2 lb2 lb2 lb0
+lb lb | l l l l l.
+			source(A)
+		shared	private	slave	unbind
+_
+dest(B)	shared	shared	shared	slave+shared	invalid
+	nonshared	shared	private	slave	unbindable
+.TE
+.P
+Note: moving a mount that resides under a shared mount is invalid.
+.P
+For further details, see
+.I Documentation/filesystems/sharedsubtree.rst
+in the kernel source tree.
+.\"
+.SS Mount semantics
+Suppose that we use the following command to create a mount:
+.P
+.in +4n
+.EX
+mount device B/b
+.EE
+.in
+.P
+Here,
+.I B
+is the destination mount, and
+.I b
+is a subdirectory path under the mount point
+.IR B .
+The propagation type of the resulting mount,
+.IR B/b ,
+follows the same rules as for a bind mount,
+where the propagation type of the source mount
+is considered always to be private.
+.\"
+.SS Unmount semantics
+Suppose that we use the following command to tear down a mount:
+.P
+.in +4n
+.EX
+umount A
+.EE
+.in
+.P
+Here,
+.I A
+is a mount on
+.IR B/b ,
+where
+.I B
+is the parent mount and
+.I b
+is a subdirectory path under the mount point
+.IR B .
+If
+.B B
+is shared, then all most-recently-mounted mounts at
+.I b
+on mounts that receive propagation from mount
+.I B
+and do not have submounts under them are unmounted.
+.\"
+.SS The /proc/ pid /mountinfo "propagate_from" tag
+The
+.I propagate_from:X
+tag is shown in the optional fields of a
+.IR /proc/ pid /mountinfo
+record in cases where a process can't see a slave's immediate master
+(i.e., the pathname of the master is not reachable from
+the filesystem root directory)
+and so cannot determine the
+chain of propagation between the mounts it can see.
+.P
+In the following example, we first create a two-link master-slave chain
+between the mounts
+.IR /mnt ,
+.IR /tmp/etc ,
+and
+.IR /mnt/tmp/etc .
+Then the
+.BR chroot (1)
+command is used to make the
+.I /tmp/etc
+mount point unreachable from the root directory,
+creating a situation where the master of
+.I /mnt/tmp/etc
+is not reachable from the (new) root directory of the process.
+.P
+First, we bind mount the root directory onto
+.I /mnt
+and then bind mount
+.I /proc
+at
+.I /mnt/proc
+so that after the later
+.BR chroot (1)
+the
+.BR proc (5)
+filesystem remains visible at the correct location
+in the chroot-ed environment.
+.P
+.in +4n
+.EX
+# \fBmkdir \-p /mnt/proc\fP
+# \fBmount \-\-bind / /mnt\fP
+# \fBmount \-\-bind /proc /mnt/proc\fP
+.EE
+.in
+.P
+Next, we ensure that the
+.I /mnt
+mount is a shared mount in a new peer group (with no peers):
+.P
+.in +4n
+.EX
+# \fBmount \-\-make\-private /mnt\fP  # Isolate from any previous peer group
+# \fBmount \-\-make\-shared /mnt\fP
+# \fBcat /proc/self/mountinfo | grep \[aq]/mnt\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+239 61 8:2 / /mnt ... shared:102
+248 239 0:4 / /mnt/proc ... shared:5
+.EE
+.in
+.P
+Next, we bind mount
+.I /mnt/etc
+onto
+.IR /tmp/etc :
+.P
+.in +4n
+.EX
+# \fBmkdir \-p /tmp/etc\fP
+# \fBmount \-\-bind /mnt/etc /tmp/etc\fP
+# \fBcat /proc/self/mountinfo | egrep \[aq]/mnt|/tmp/\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+239 61 8:2 / /mnt ... shared:102
+248 239 0:4 / /mnt/proc ... shared:5
+267 40 8:2 /etc /tmp/etc ... shared:102
+.EE
+.in
+.P
+Initially, these two mounts are in the same peer group,
+but we then make the
+.I /tmp/etc
+a slave of
+.IR /mnt/etc ,
+and then make
+.I /tmp/etc
+shared as well,
+so that it can propagate events to the next slave in the chain:
+.P
+.in +4n
+.EX
+# \fBmount \-\-make\-slave /tmp/etc\fP
+# \fBmount \-\-make\-shared /tmp/etc\fP
+# \fBcat /proc/self/mountinfo | egrep \[aq]/mnt|/tmp/\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+239 61 8:2 / /mnt ... shared:102
+248 239 0:4 / /mnt/proc ... shared:5
+267 40 8:2 /etc /tmp/etc ... shared:105 master:102
+.EE
+.in
+.P
+Then we bind mount
+.I /tmp/etc
+onto
+.IR /mnt/tmp/etc .
+Again, the two mounts are initially in the same peer group,
+but we then make
+.I /mnt/tmp/etc
+a slave of
+.IR /tmp/etc :
+.P
+.in +4n
+.EX
+# \fBmkdir \-p /mnt/tmp/etc\fP
+# \fBmount \-\-bind /tmp/etc /mnt/tmp/etc\fP
+# \fBmount \-\-make\-slave /mnt/tmp/etc\fP
+# \fBcat /proc/self/mountinfo | egrep \[aq]/mnt|/tmp/\[aq] | sed \[aq]s/ \- .*//\[aq]\fP
+239 61 8:2 / /mnt ... shared:102
+248 239 0:4 / /mnt/proc ... shared:5
+267 40 8:2 /etc /tmp/etc ... shared:105 master:102
+273 239 8:2 /etc /mnt/tmp/etc ... master:105
+.EE
+.in
+.P
+From the above, we see that
+.I /mnt
+is the master of the slave
+.IR /tmp/etc ,
+which in turn is the master of the slave
+.IR /mnt/tmp/etc .
+.P
+We then
+.BR chroot (1)
+to the
+.I /mnt
+directory, which renders the mount with ID 267 unreachable
+from the (new) root directory:
+.P
+.in +4n
+.EX
+# \fBchroot /mnt\fP
+.EE
+.in
+.P
+When we examine the state of the mounts inside the chroot-ed environment,
+we see the following:
+.P
+.in +4n
+.EX
+# \fBcat /proc/self/mountinfo | sed \[aq]s/ \- .*//\[aq]\fP
+239 61 8:2 / / ... shared:102
+248 239 0:4 / /proc ... shared:5
+273 239 8:2 /etc /tmp/etc ... master:105 propagate_from:102
+.EE
+.in
+.P
+Above, we see that the mount with ID 273
+is a slave whose master is the peer group 105.
+The mount point for that master is unreachable, and so a
+.I propagate_from
+tag is displayed, indicating that the closest dominant peer group
+(i.e., the nearest reachable mount in the slave chain)
+is the peer group with the ID 102 (corresponding to the
+.I /mnt
+mount point before the
+.BR chroot (1)
+was performed).
+.\"
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 2.4.19.
+.\"
+.SH NOTES
+The propagation type assigned to a new mount depends
+on the propagation type of the parent mount.
+If the mount has a parent (i.e., it is a non-root mount
+point) and the propagation type of the parent is
+.BR MS_SHARED ,
+then the propagation type of the new mount is also
+.BR MS_SHARED .
+Otherwise, the propagation type of the new mount is
+.BR MS_PRIVATE .
+.P
+Notwithstanding the fact that the default propagation type
+for new mount is in many cases
+.BR MS_PRIVATE ,
+.B MS_SHARED
+is typically more useful.
+For this reason,
+.BR systemd (1)
+automatically remounts all mounts as
+.B MS_SHARED
+on system startup.
+Thus, on most modern systems, the default propagation type is in practice
+.BR MS_SHARED .
+.P
+Since, when one uses
+.BR unshare (1)
+to create a mount namespace,
+the goal is commonly to provide full isolation of the mounts
+in the new namespace,
+.BR unshare (1)
+(since
+.I util\-linux
+2.27) in turn reverses the step performed by
+.BR systemd (1),
+by making all mounts private in the new namespace.
+That is,
+.BR unshare (1)
+performs the equivalent of the following in the new mount namespace:
+.P
+.in +4n
+.EX
+mount \-\-make\-rprivate /
+.EE
+.in
+.P
+To prevent this, one can use the
+.I \-\-propagation\~unchanged
+option to
+.BR unshare (1).
+.P
+An application that creates a new mount namespace directly using
+.BR clone (2)
+or
+.BR unshare (2)
+may desire to prevent propagation of mount events to other mount namespaces
+(as is done by
+.BR unshare (1)).
+This can be done by changing the propagation type of
+mounts in the new namespace to either
+.B MS_SLAVE
+or
+.BR MS_PRIVATE ,
+using a call such as the following:
+.P
+.in +4n
+.EX
+mount(NULL, "/", MS_SLAVE | MS_REC, NULL);
+.EE
+.in
+.P
+For a discussion of propagation types when moving mounts
+.RB ( MS_MOVE )
+and creating bind mounts
+.RB ( MS_BIND ),
+see
+.IR Documentation/filesystems/sharedsubtree.rst .
+.\"
+.\" ============================================================
+.\"
+.SS Restrictions on mount namespaces
+Note the following points with respect to mount namespaces:
+.IP [1] 5
+Each mount namespace has an owner user namespace.
+As explained above, when a new mount namespace is created,
+its mount list is initialized as a copy of the mount list
+of another mount namespace.
+If the new namespace and the namespace from which the mount list
+was copied are owned by different user namespaces,
+then the new mount namespace is considered
+.IR "less privileged" .
+.IP [2]
+When creating a less privileged mount namespace,
+shared mounts are reduced to slave mounts.
+This ensures that mappings performed in less
+privileged mount namespaces will not propagate to more privileged
+mount namespaces.
+.IP [3]
+Mounts that come as a single unit from a more privileged mount namespace are
+locked together and may not be separated in a less privileged mount
+namespace.
+(The
+.BR unshare (2)
+.B CLONE_NEWNS
+operation brings across all of the mounts from the original
+mount namespace as a single unit,
+and recursive mounts that propagate between
+mount namespaces propagate as a single unit.)
+.IP
+In this context, "may not be separated" means that the mounts
+are locked so that they may not be individually unmounted.
+Consider the following example:
+.IP
+.in +4n
+.EX
+$ \fBsudo sh\fP
+# \fBmount \-\-bind /dev/null /etc/shadow\fP
+# \fBcat /etc/shadow\fP       # Produces no output
+.EE
+.in
+.IP
+The above steps, performed in a more privileged mount namespace,
+have created a bind mount that
+obscures the contents of the shadow password file,
+.IR /etc/shadow .
+For security reasons, it should not be possible to
+.BR umount (2)
+that mount in a less privileged mount namespace,
+since that would reveal the contents of
+.IR /etc/shadow .
+.IP
+Suppose we now create a new mount namespace
+owned by a new user namespace.
+The new mount namespace will inherit copies of all of the mounts
+from the previous mount namespace.
+However, those mounts will be locked because the new mount namespace
+is less privileged.
+Consequently, an attempt to
+.BR umount (2)
+the mount fails as show
+in the following step:
+.IP
+.in +4n
+.EX
+# \fBunshare \-\-user \-\-map\-root\-user \-\-mount \e\fP
+               \fBstrace \-o /tmp/log \e\fP
+               \fBumount /mnt/dir\fP
+umount: /etc/shadow: not mounted.
+# \fBgrep \[aq]\[ha]umount\[aq] /tmp/log\fP
+umount2("/etc/shadow", 0)     = \-1 EINVAL (Invalid argument)
+.EE
+.in
+.IP
+The error message from
+.BR mount (8)
+is a little confusing, but the
+.BR strace (1)
+output reveals that the underlying
+.BR umount2 (2)
+system call failed with the error
+.BR EINVAL ,
+which is the error that the kernel returns to indicate that
+the mount is locked.
+.IP
+Note, however, that it is possible to stack (and unstack) a
+mount on top of one of the inherited locked mounts in a
+less privileged mount namespace:
+.IP
+.in +4n
+.EX
+# \fBecho \[aq]aaaaa\[aq] > /tmp/a\fP    # File to mount onto /etc/shadow
+# \fBunshare \-\-user \-\-map\-root\-user \-\-mount \e\fP
+    \fBsh \-c \[aq]mount \-\-bind /tmp/a /etc/shadow; cat /etc/shadow\[aq]\fP
+aaaaa
+# \fBumount /etc/shadow\fP
+.EE
+.in
+.IP
+The final
+.BR umount (8)
+command above, which is performed in the initial mount namespace,
+makes the original
+.I /etc/shadow
+file once more visible in that namespace.
+.IP [4]
+Following on from point [3],
+note that it is possible to
+.BR umount (2)
+an entire subtree of mounts that
+propagated as a unit into a less privileged mount namespace,
+as illustrated in the following example.
+.IP
+First, we create new user and mount namespaces using
+.BR unshare (1).
+In the new mount namespace,
+the propagation type of all mounts is set to private.
+We then create a shared bind mount at
+.IR /mnt ,
+and a small hierarchy of mounts underneath that mount.
+.IP
+.in +4n
+.EX
+$ \fBPS1=\[aq]ns1# \[aq] sudo unshare \-\-user \-\-map\-root\-user \e\fP
+                       \fB\-\-mount \-\-propagation private bash\fP
+ns1# \fBecho $$\fP        # We need the PID of this shell later
+778501
+ns1# \fBmount \-\-make\-shared \-\-bind /mnt /mnt\fP
+ns1# \fBmkdir /mnt/x\fP
+ns1# \fBmount \-\-make\-private \-t tmpfs none /mnt/x\fP
+ns1# \fBmkdir /mnt/x/y\fP
+ns1# \fBmount \-\-make\-private \-t tmpfs none /mnt/x/y\fP
+ns1# \fBgrep /mnt /proc/self/mountinfo | sed \[aq]s/ \- .*//\[aq]\fP
+986 83 8:5 /mnt /mnt rw,relatime shared:344
+989 986 0:56 / /mnt/x rw,relatime
+990 989 0:57 / /mnt/x/y rw,relatime
+.EE
+.in
+.IP
+Continuing in the same shell session,
+we then create a second shell in a new user namespace and a new
+(less privileged) mount namespace and
+check the state of the propagated mounts rooted at
+.IR /mnt .
+.IP
+.in +4n
+.EX
+ns1# \fBPS1=\[aq]ns2# \[aq] unshare \-\-user \-\-map\-root\-user \e\fP
+                       \fB\-\-mount \-\-propagation unchanged bash\fP
+ns2# \fBgrep /mnt /proc/self/mountinfo | sed \[aq]s/ \- .*//\[aq]\fP
+1239 1204 8:5 /mnt /mnt rw,relatime master:344
+1240 1239 0:56 / /mnt/x rw,relatime
+1241 1240 0:57 / /mnt/x/y rw,relatime
+.EE
+.in
+.IP
+Of note in the above output is that the propagation type of the mount
+.I /mnt
+has been reduced to slave, as explained in point [2].
+This means that submount events will propagate from the master
+.I /mnt
+in "ns1", but propagation will not occur in the opposite direction.
+.IP
+From a separate terminal window, we then use
+.BR nsenter (1)
+to enter the mount and user namespaces corresponding to "ns1".
+In that terminal window, we then recursively bind mount
+.I /mnt/x
+at the location
+.IR /mnt/ppp .
+.IP
+.in +4n
+.EX
+$ \fBPS1=\[aq]ns3# \[aq] sudo nsenter \-t 778501 \-\-user \-\-mount\fP
+ns3# \fBmount \-\-rbind \-\-make\-private /mnt/x /mnt/ppp\fP
+ns3# \fBgrep /mnt /proc/self/mountinfo | sed \[aq]s/ \- .*//\[aq]\fP
+986 83 8:5 /mnt /mnt rw,relatime shared:344
+989 986 0:56 / /mnt/x rw,relatime
+990 989 0:57 / /mnt/x/y rw,relatime
+1242 986 0:56 / /mnt/ppp rw,relatime
+1243 1242 0:57 / /mnt/ppp/y rw,relatime shared:518
+.EE
+.in
+.IP
+Because the propagation type of the parent mount,
+.IR /mnt ,
+was shared, the recursive bind mount propagated a small subtree of
+mounts under the slave mount
+.I /mnt
+into "ns2",
+as can be verified by executing the following command in that shell session:
+.IP
+.in +4n
+.EX
+ns2# \fBgrep /mnt /proc/self/mountinfo | sed \[aq]s/ \- .*//\[aq]\fP
+1239 1204 8:5 /mnt /mnt rw,relatime master:344
+1240 1239 0:56 / /mnt/x rw,relatime
+1241 1240 0:57 / /mnt/x/y rw,relatime
+1244 1239 0:56 / /mnt/ppp rw,relatime
+1245 1244 0:57 / /mnt/ppp/y rw,relatime master:518
+.EE
+.in
+.IP
+While it is not possible to
+.BR umount (2)
+a part of the propagated subtree
+.RI ( /mnt/ppp/y )
+in "ns2",
+it is possible to
+.BR umount (2)
+the entire subtree,
+as shown by the following commands:
+.IP
+.in +4n
+.EX
+ns2# \fBumount /mnt/ppp/y\fP
+umount: /mnt/ppp/y: not mounted.
+ns2# \fBumount \-l /mnt/ppp | sed \[aq]s/ \- .*//\[aq]\fP      # Succeeds...
+ns2# \fBgrep /mnt /proc/self/mountinfo\fP
+1239 1204 8:5 /mnt /mnt rw,relatime master:344
+1240 1239 0:56 / /mnt/x rw,relatime
+1241 1240 0:57 / /mnt/x/y rw,relatime
+.EE
+.in
+.IP [5]
+The
+.BR mount (2)
+flags
+.BR MS_RDONLY ,
+.BR MS_NOSUID ,
+.BR MS_NOEXEC ,
+and the "atime" flags
+.RB ( MS_NOATIME ,
+.BR MS_NODIRATIME ,
+.BR MS_RELATIME )
+settings become locked
+.\" commit 9566d6742852c527bf5af38af5cbb878dad75705
+.\" Author: Eric W. Biederman <ebiederm@xmission.com>
+.\" Date:   Mon Jul 28 17:26:07 2014 -0700
+.\"
+.\"      mnt: Correct permission checks in do_remount
+.\"
+when propagated from a more privileged to
+a less privileged mount namespace,
+and may not be changed in the less privileged mount namespace.
+.IP
+This point is illustrated in the following example where,
+in a more privileged mount namespace,
+we create a bind mount that is marked as read-only.
+For security reasons,
+it should not be possible to make the mount writable in
+a less privileged mount namespace, and indeed the kernel prevents this:
+.IP
+.in +4n
+.EX
+$ \fBsudo mkdir /mnt/dir\fP
+$ \fBsudo mount \-\-bind \-o ro /some/path /mnt/dir\fP
+$ \fBsudo unshare \-\-user \-\-map\-root\-user \-\-mount \e\fP
+               \fBmount \-o remount,rw /mnt/dir\fP
+mount: /mnt/dir: permission denied.
+.EE
+.in
+.IP [6]
+.\" (As of 3.18-rc1 (in Al Viro's 2014-08-30 vfs.git#for-next tree))
+A file or directory that is a mount point in one namespace that is not
+a mount point in another namespace, may be renamed, unlinked, or removed
+.RB ( rmdir (2))
+in the mount namespace in which it is not a mount point
+(subject to the usual permission checks).
+Consequently, the mount point is removed in the mount namespace
+where it was a mount point.
+.IP
+Previously (before Linux 3.18),
+.\" mtk: The change was in Linux 3.18, I think, with this commit:
+.\"     commit 8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe
+.\"     Author: Eric W. Biederman <ebiederman@twitter.com>
+.\"     Date:   Tue Oct 1 18:33:48 2013 -0700
+.\"
+.\"         vfs: Lazily remove mounts on unlinked files and directories.
+attempting to unlink, rename, or remove a file or directory
+that was a mount point in another mount namespace would result in the error
+.BR EBUSY .
+That behavior had technical problems of enforcement (e.g., for NFS)
+and permitted denial-of-service attacks against more privileged users
+(i.e., preventing individual files from being updated
+by bind mounting on top of them).
+.SH EXAMPLES
+See
+.BR pivot_root (2).
+.SH SEE ALSO
+.BR unshare (1),
+.BR clone (2),
+.BR mount (2),
+.BR mount_setattr (2),
+.BR pivot_root (2),
+.BR setns (2),
+.BR umount (2),
+.BR unshare (2),
+.BR proc (5),
+.BR namespaces (7),
+.BR user_namespaces (7),
+.BR findmnt (8),
+.BR mount (8),
+.BR pam_namespace (8),
+.BR pivot_root (8),
+.BR umount (8)
+.P
+.I Documentation/filesystems/sharedsubtree.rst
+in the kernel source tree.
diff --git a/man/man7/mq_overview.7 b/man/man7/mq_overview.7
new file mode 100644
index 000000000..51ad14d3a
--- /dev/null
+++ b/man/man7/mq_overview.7
@@ -0,0 +1,389 @@
+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH mq_overview 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+mq_overview \- overview of POSIX message queues
+.SH DESCRIPTION
+POSIX message queues allow processes to exchange data in
+the form of messages.
+This API is distinct from that provided by System V message queues
+.RB ( msgget (2),
+.BR msgsnd (2),
+.BR msgrcv (2),
+etc.), but provides similar functionality.
+.P
+Message queues are created and opened using
+.BR mq_open (3);
+this function returns a
+.I message queue descriptor
+.RI ( mqd_t ),
+which is used to refer to the open message queue in later calls.
+Each message queue is identified by a name of the form
+.IR /somename ;
+that is, a null-terminated string of up to
+.B NAME_MAX
+(i.e., 255) characters consisting of an initial slash,
+followed by one or more characters, none of which are slashes.
+Two processes can operate on the same queue by passing the same name to
+.BR mq_open (3).
+.P
+Messages are transferred to and from a queue using
+.BR mq_send (3)
+and
+.BR mq_receive (3).
+When a process has finished using the queue, it closes it using
+.BR mq_close (3),
+and when the queue is no longer required, it can be deleted using
+.BR mq_unlink (3).
+Queue attributes can be retrieved and (in some cases) modified using
+.BR mq_getattr (3)
+and
+.BR mq_setattr (3).
+A process can request asynchronous notification
+of the arrival of a message on a previously empty queue using
+.BR mq_notify (3).
+.P
+A message queue descriptor is a reference to an
+.I "open message queue description"
+(see
+.BR open (2)).
+After a
+.BR fork (2),
+a child inherits copies of its parent's message queue descriptors,
+and these descriptors refer to the same open message queue descriptions
+as the corresponding message queue descriptors in the parent.
+Corresponding message queue descriptors in the two processes share the flags
+.RI ( mq_flags )
+that are associated with the open message queue description.
+.P
+Each message has an associated
+.IR priority ,
+and messages are always delivered to the receiving process
+highest priority first.
+Message priorities range from 0 (low) to
+.I sysconf(_SC_MQ_PRIO_MAX)\ \-\ 1
+(high).
+On Linux,
+.I sysconf(_SC_MQ_PRIO_MAX)
+returns 32768, but POSIX.1 requires only that
+an implementation support at least priorities in the range 0 to 31;
+some implementations provide only this range.
+.P
+The remainder of this section describes some specific details
+of the Linux implementation of POSIX message queues.
+.SS Library interfaces and system calls
+In most cases the
+.BR mq_* ()
+library interfaces listed above are implemented
+on top of underlying system calls of the same name.
+Deviations from this scheme are indicated in the following table:
+.RS
+.TS
+lB lB
+l l.
+Library interface	System call
+mq_close(3)	close(2)
+mq_getattr(3)	mq_getsetattr(2)
+mq_notify(3)	mq_notify(2)
+mq_open(3)	mq_open(2)
+mq_receive(3)	mq_timedreceive(2)
+mq_send(3)	mq_timedsend(2)
+mq_setattr(3)	mq_getsetattr(2)
+mq_timedreceive(3)	mq_timedreceive(2)
+mq_timedsend(3)	mq_timedsend(2)
+mq_unlink(3)	mq_unlink(2)
+.TE
+.RE
+.SS Versions
+POSIX message queues have been supported since Linux 2.6.6.
+glibc support has been provided since glibc 2.3.4.
+.SS Kernel configuration
+Support for POSIX message queues is configurable via the
+.B CONFIG_POSIX_MQUEUE
+kernel configuration option.
+This option is enabled by default.
+.SS Persistence
+POSIX message queues have kernel persistence:
+if not removed by
+.BR mq_unlink (3),
+a message queue will exist until the system is shut down.
+.SS Linking
+Programs using the POSIX message queue API must be compiled with
+.I cc \-lrt
+to link against the real-time library,
+.IR librt .
+.SS /proc interfaces
+The following interfaces can be used to limit the amount of
+kernel memory consumed by POSIX message queues and to set
+the default attributes for new message queues:
+.TP
+.IR /proc/sys/fs/mqueue/msg_default " (since Linux 3.5)"
+This file defines the value used for a new queue's
+.I mq_maxmsg
+setting when the queue is created with a call to
+.BR mq_open (3)
+where
+.I attr
+is specified as NULL.
+The default value for this file is 10.
+The minimum and maximum are as for
+.IR /proc/sys/fs/mqueue/msg_max .
+A new queue's default
+.I mq_maxmsg
+value will be the smaller of
+.I msg_default
+and
+.IR msg_max .
+Before Linux 2.6.28, the default
+.I mq_maxmsg
+was 10;
+from Linux 2.6.28 to Linux 3.4, the default was the value defined for the
+.I msg_max
+limit.
+.TP
+.I /proc/sys/fs/mqueue/msg_max
+This file can be used to view and change the ceiling value for the
+maximum number of messages in a queue.
+This value acts as a ceiling on the
+.I attr\->mq_maxmsg
+argument given to
+.BR mq_open (3).
+The default value for
+.I msg_max
+is 10.
+The minimum value is 1 (10 before Linux 2.6.28).
+The upper limit is
+.BR HARD_MSGMAX .
+The
+.I msg_max
+limit is ignored for privileged processes
+.RB ( CAP_SYS_RESOURCE ),
+but the
+.B HARD_MSGMAX
+ceiling is nevertheless imposed.
+.IP
+The definition of
+.B HARD_MSGMAX
+has changed across kernel versions:
+.RS
+.IP \[bu] 3
+Up to Linux 2.6.32:
+.I 131072\~/\~sizeof(void\~*)
+.IP \[bu]
+Linux 2.6.33 to Linux 3.4:
+.I (32768\~*\~sizeof(void\~*) / 4)
+.IP \[bu]
+Since Linux 3.5:
+.\" commit 5b5c4d1a1440e94994c73dddbad7be0676cd8b9a
+65,536
+.RE
+.TP
+.IR /proc/sys/fs/mqueue/msgsize_default " (since Linux 3.5)"
+This file defines the value used for a new queue's
+.I mq_msgsize
+setting when the queue is created with a call to
+.BR mq_open (3)
+where
+.I attr
+is specified as NULL.
+The default value for this file is 8192 (bytes).
+The minimum and maximum are as for
+.IR /proc/sys/fs/mqueue/msgsize_max .
+If
+.I msgsize_default
+exceeds
+.IR msgsize_max ,
+a new queue's default
+.I mq_msgsize
+value is capped to the
+.I msgsize_max
+limit.
+Before Linux 2.6.28, the default
+.I mq_msgsize
+was 8192;
+from Linux 2.6.28 to Linux 3.4, the default was the value defined for the
+.I msgsize_max
+limit.
+.TP
+.I /proc/sys/fs/mqueue/msgsize_max
+This file can be used to view and change the ceiling on the
+maximum message size.
+This value acts as a ceiling on the
+.I attr\->mq_msgsize
+argument given to
+.BR mq_open (3).
+The default value for
+.I msgsize_max
+is 8192 bytes.
+The minimum value is 128 (8192 before Linux 2.6.28).
+The upper limit for
+.I msgsize_max
+has varied across kernel versions:
+.RS
+.IP \[bu] 3
+Before Linux 2.6.28, the upper limit is
+.BR INT_MAX .
+.IP \[bu]
+From Linux 2.6.28 to Linux 3.4, the limit is 1,048,576.
+.IP \[bu]
+Since Linux 3.5, the limit is 16,777,216
+.RB ( HARD_MSGSIZEMAX ).
+.RE
+.IP
+The
+.I msgsize_max
+limit is ignored for privileged process
+.RB ( CAP_SYS_RESOURCE ),
+but, since Linux 3.5, the
+.B HARD_MSGSIZEMAX
+ceiling is enforced for privileged processes.
+.TP
+.I /proc/sys/fs/mqueue/queues_max
+This file can be used to view and change the system-wide limit on the
+number of message queues that can be created.
+The default value for
+.I queues_max
+is 256.
+No ceiling is imposed on the
+.I queues_max
+limit; privileged processes
+.RB ( CAP_SYS_RESOURCE )
+can exceed the limit (but see BUGS).
+.SS Resource limit
+The
+.B RLIMIT_MSGQUEUE
+resource limit, which places a limit on the amount of space
+that can be consumed by all of the message queues
+belonging to a process's real user ID, is described in
+.BR getrlimit (2).
+.SS Mounting the message queue filesystem
+On Linux, message queues are created in a virtual filesystem.
+(Other implementations may also provide such a feature,
+but the details are likely to differ.)
+This filesystem can be mounted (by the superuser) using the following
+commands:
+.P
+.in +4n
+.EX
+.RB "#" " mkdir /dev/mqueue"
+.RB "#" " mount \-t mqueue none /dev/mqueue"
+.EE
+.in
+.P
+The sticky bit is automatically enabled on the mount directory.
+.P
+After the filesystem has been mounted, the message queues on the system
+can be viewed and manipulated using the commands usually used for files
+(e.g.,
+.BR ls (1)
+and
+.BR rm (1)).
+.P
+The contents of each file in the directory consist of a single line
+containing information about the queue:
+.P
+.in +4n
+.EX
+.RB "$" " cat /dev/mqueue/mymq"
+QSIZE:129     NOTIFY:2    SIGNO:0    NOTIFY_PID:8260
+.EE
+.in
+.P
+These fields are as follows:
+.TP
+.B QSIZE
+Number of bytes of data in all messages in the queue (but see BUGS).
+.TP
+.B NOTIFY_PID
+If this is nonzero, then the process with this PID has used
+.BR mq_notify (3)
+to register for asynchronous message notification,
+and the remaining fields describe how notification occurs.
+.TP
+.B NOTIFY
+Notification method:
+0 is
+.BR SIGEV_SIGNAL ;
+1 is
+.BR SIGEV_NONE ;
+and
+2 is
+.BR SIGEV_THREAD .
+.TP
+.B SIGNO
+Signal number to be used for
+.BR SIGEV_SIGNAL .
+.SS Linux implementation of message queue descriptors
+On Linux, a message queue descriptor is actually a file descriptor.
+(POSIX does not require such an implementation.)
+This means that a message queue descriptor can be monitored using
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7).
+This is not portable.
+.P
+The close-on-exec flag (see
+.BR open (2))
+is automatically set on the file descriptor returned by
+.BR mq_open (2).
+.SS IPC namespaces
+For a discussion of the interaction of POSIX message queue objects and
+IPC namespaces, see
+.BR ipc_namespaces (7).
+.SH NOTES
+System V message queues
+.RB ( msgget (2),
+.BR msgsnd (2),
+.BR msgrcv (2),
+etc.) are an older API for exchanging messages between processes.
+POSIX message queues provide a better designed interface than
+System V message queues;
+on the other hand POSIX message queues are less widely available
+(especially on older systems) than System V message queues.
+.P
+Linux does not currently (Linux 2.6.26) support the use of access control
+lists (ACLs) for POSIX message queues.
+.SH BUGS
+Since Linux 3.5 to Linux 3.14, the kernel imposed a ceiling of 1024
+.RB ( HARD_QUEUESMAX )
+on the value to which the
+.I queues_max
+limit could be raised,
+and the ceiling was enforced even for privileged processes.
+This ceiling value was removed in Linux 3.14,
+and patches to stable Linux 3.5.x to Linux 3.13.x also removed the ceiling.
+.P
+As originally implemented (and documented),
+the QSIZE field displayed the total number of (user-supplied)
+bytes in all messages in the message queue.
+Some changes in Linux 3.5
+.\" commit d6629859b36d
+inadvertently changed the behavior,
+so that this field also included a count of kernel overhead bytes
+used to store the messages in the queue.
+This behavioral regression was rectified in Linux 4.2
+.\" commit de54b9ac253787c366bbfb28d901a31954eb3511
+(and earlier stable kernel series),
+so that the count once more included just the bytes of user data
+in messages in the queue.
+.SH EXAMPLES
+An example of the use of various message queue functions is shown in
+.BR mq_notify (3).
+.SH SEE ALSO
+.BR getrlimit (2),
+.BR mq_getsetattr (2),
+.BR poll (2),
+.BR select (2),
+.BR mq_close (3),
+.BR mq_getattr (3),
+.BR mq_notify (3),
+.BR mq_open (3),
+.BR mq_receive (3),
+.BR mq_send (3),
+.BR mq_unlink (3),
+.BR epoll (7),
+.BR namespaces (7)
diff --git a/man/man7/namespaces.7 b/man/man7/namespaces.7
new file mode 100644
index 000000000..bdcdde3c8
--- /dev/null
+++ b/man/man7/namespaces.7
@@ -0,0 +1,417 @@
+'\" t
+.\" Copyright (c) 2013, 2016, 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (c) 2012 by Eric W. Biederman <ebiederm@xmission.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+namespaces \- overview of Linux namespaces
+.SH DESCRIPTION
+A namespace wraps a global system resource in an abstraction that
+makes it appear to the processes within the namespace that they
+have their own isolated instance of the global resource.
+Changes to the global resource are visible to other processes
+that are members of the namespace, but are invisible to other processes.
+One use of namespaces is to implement containers.
+.P
+This page provides pointers to information on the various namespace types,
+describes the associated
+.I /proc
+files, and summarizes the APIs for working with namespaces.
+.\"
+.SS Namespace types
+The following table shows the namespace types available on Linux.
+The second column of the table shows the flag value that is used to specify
+the namespace type in various APIs.
+The third column identifies the manual page that provides details
+on the namespace type.
+The last column is a summary of the resources that are isolated by
+the namespace type.
+.TS
+lB lB lB lB
+l1 lB1 l1 l.
+Namespace	Flag	Page	Isolates
+Cgroup	CLONE_NEWCGROUP	\fBcgroup_namespaces\fP(7)	T{
+Cgroup root directory
+T}
+IPC	CLONE_NEWIPC	\fBipc_namespaces\fP(7)	T{
+System V IPC,
+POSIX message queues
+T}
+Network	CLONE_NEWNET	\fBnetwork_namespaces\fP(7)	T{
+Network devices,
+stacks, ports, etc.
+T}
+Mount	CLONE_NEWNS	\fBmount_namespaces\fP(7)	Mount points
+PID	CLONE_NEWPID	\fBpid_namespaces\fP(7)	Process IDs
+Time	CLONE_NEWTIME	\fBtime_namespaces\fP(7)	T{
+Boot and monotonic
+clocks
+T}
+User	CLONE_NEWUSER	\fBuser_namespaces\fP(7)	T{
+User and group IDs
+T}
+UTS	CLONE_NEWUTS	\fButs_namespaces\fP(7)	T{
+Hostname and NIS
+domain name
+T}
+.TE
+.\"
+.\" ==================== The namespaces API ====================
+.\"
+.SS The namespaces API
+As well as various
+.I /proc
+files described below,
+the namespaces API includes the following system calls:
+.TP
+.BR clone (2)
+The
+.BR clone (2)
+system call creates a new process.
+If the
+.I flags
+argument of the call specifies one or more of the
+.B CLONE_NEW*
+flags listed above, then new namespaces are created for each flag,
+and the child process is made a member of those namespaces.
+(This system call also implements a number of features
+unrelated to namespaces.)
+.TP
+.BR setns (2)
+The
+.BR setns (2)
+system call allows the calling process to join an existing namespace.
+The namespace to join is specified via a file descriptor that refers to
+one of the
+.IR /proc/ pid /ns
+files described below.
+.TP
+.BR unshare (2)
+The
+.BR unshare (2)
+system call moves the calling process to a new namespace.
+If the
+.I flags
+argument of the call specifies one or more of the
+.B CLONE_NEW*
+flags listed above, then new namespaces are created for each flag,
+and the calling process is made a member of those namespaces.
+(This system call also implements a number of features
+unrelated to namespaces.)
+.TP
+.BR ioctl (2)
+Various
+.BR ioctl (2)
+operations can be used to discover information about namespaces.
+These operations are described in
+.BR ioctl_ns (2).
+.P
+Creation of new namespaces using
+.BR clone (2)
+and
+.BR unshare (2)
+in most cases requires the
+.B CAP_SYS_ADMIN
+capability, since, in the new namespace,
+the creator will have the power to change global resources
+that are visible to other processes that are subsequently created in,
+or join the namespace.
+User namespaces are the exception: since Linux 3.8,
+no privilege is required to create a user namespace.
+.\"
+.\" ==================== The /proc/[pid]/ns/ directory ====================
+.\"
+.SS The \fI/proc/\fPpid\fI/ns/\fP directory
+Each process has a
+.IR /proc/ pid /ns/
+.\" See commit 6b4e306aa3dc94a0545eb9279475b1ab6209a31f
+subdirectory containing one entry for each namespace that
+supports being manipulated by
+.BR setns (2):
+.P
+.in +4n
+.EX
+$ \fBls \-l /proc/$$/ns | awk \[aq]{print $1, $9, $10, $11}\[aq]\fP
+total 0
+lrwxrwxrwx. cgroup \-> cgroup:[4026531835]
+lrwxrwxrwx. ipc \-> ipc:[4026531839]
+lrwxrwxrwx. mnt \-> mnt:[4026531840]
+lrwxrwxrwx. net \-> net:[4026531969]
+lrwxrwxrwx. pid \-> pid:[4026531836]
+lrwxrwxrwx. pid_for_children \-> pid:[4026531834]
+lrwxrwxrwx. time \-> time:[4026531834]
+lrwxrwxrwx. time_for_children \-> time:[4026531834]
+lrwxrwxrwx. user \-> user:[4026531837]
+lrwxrwxrwx. uts \-> uts:[4026531838]
+.EE
+.in
+.P
+Bind mounting (see
+.BR mount (2))
+one of the files in this directory
+to somewhere else in the filesystem keeps
+the corresponding namespace of the process specified by
+.I pid
+alive even if all processes currently in the namespace terminate.
+.P
+Opening one of the files in this directory
+(or a file that is bind mounted to one of these files)
+returns a file handle for
+the corresponding namespace of the process specified by
+.IR pid .
+As long as this file descriptor remains open,
+the namespace will remain alive,
+even if all processes in the namespace terminate.
+The file descriptor can be passed to
+.BR setns (2).
+.P
+In Linux 3.7 and earlier, these files were visible as hard links.
+Since Linux 3.8,
+.\" commit bf056bfa80596a5d14b26b17276a56a0dcb080e5
+they appear as symbolic links.
+If two processes are in the same namespace,
+then the device IDs and inode numbers of their
+.IR /proc/ pid /ns/ xxx
+symbolic links will be the same; an application can check this using the
+.I stat.st_dev
+.\" Eric Biederman: "I reserve the right for st_dev to be significant
+.\" when comparing namespaces."
+.\" https://lore.kernel.org/lkml/87poky5ca9.fsf@xmission.com/
+.\" Re: Documenting the ioctl interfaces to discover relationships...
+.\" Date: Mon, 12 Dec 2016 11:30:38 +1300
+and
+.I stat.st_ino
+fields returned by
+.BR stat (2).
+The content of this symbolic link is a string containing
+the namespace type and inode number as in the following example:
+.P
+.in +4n
+.EX
+$ \fBreadlink /proc/$$/ns/uts\fP
+uts:[4026531838]
+.EE
+.in
+.P
+The symbolic links in this subdirectory are as follows:
+.TP
+.IR /proc/ pid /ns/cgroup " (since Linux 4.6)"
+This file is a handle for the cgroup namespace of the process.
+.TP
+.IR /proc/ pid /ns/ipc " (since Linux 3.0)"
+This file is a handle for the IPC namespace of the process.
+.TP
+.IR /proc/ pid /ns/mnt " (since Linux 3.8)"
+.\" commit 8823c079ba7136dc1948d6f6dcb5f8022bde438e
+This file is a handle for the mount namespace of the process.
+.TP
+.IR /proc/ pid /ns/net " (since Linux 3.0)"
+This file is a handle for the network namespace of the process.
+.TP
+.IR /proc/ pid /ns/pid " (since Linux 3.8)"
+.\" commit 57e8391d327609cbf12d843259c968b9e5c1838f
+This file is a handle for the PID namespace of the process.
+This handle is permanent for the lifetime of the process
+(i.e., a process's PID namespace membership never changes).
+.TP
+.IR /proc/ pid /ns/pid_for_children " (since Linux 4.12)"
+.\" commit eaa0d190bfe1ed891b814a52712dcd852554cb08
+This file is a handle for the PID namespace of
+child processes created by this process.
+This can change as a consequence of calls to
+.BR unshare (2)
+and
+.BR setns (2)
+(see
+.BR pid_namespaces (7)),
+so the file may differ from
+.IR /proc/ pid /ns/pid .
+The symbolic link gains a value only after the first child process
+is created in the namespace.
+(Beforehand,
+.BR readlink (2)
+of the symbolic link will return an empty buffer.)
+.TP
+.IR /proc/ pid /ns/time " (since Linux 5.6)"
+This file is a handle for the time namespace of the process.
+.TP
+.IR /proc/ pid /ns/time_for_children " (since Linux 5.6)"
+This file is a handle for the time namespace of
+child processes created by this process.
+This can change as a consequence of calls to
+.BR unshare (2)
+and
+.BR setns (2)
+(see
+.BR time_namespaces (7)),
+so the file may differ from
+.IR /proc/ pid /ns/time .
+.TP
+.IR /proc/ pid /ns/user " (since Linux 3.8)"
+.\" commit cde1975bc242f3e1072bde623ef378e547b73f91
+This file is a handle for the user namespace of the process.
+.TP
+.IR /proc/ pid /ns/uts " (since Linux 3.0)"
+This file is a handle for the UTS namespace of the process.
+.P
+Permission to dereference or read
+.RB ( readlink (2))
+these symbolic links is governed by a ptrace access mode
+.B PTRACE_MODE_READ_FSCREDS
+check; see
+.BR ptrace (2).
+.\"
+.\" ==================== The /proc/sys/user directory ====================
+.\"
+.SS The \fI/proc/sys/user\fP directory
+The files in the
+.I /proc/sys/user
+directory (which is present since Linux 4.9) expose limits
+on the number of namespaces of various types that can be created.
+The files are as follows:
+.TP
+.I max_cgroup_namespaces
+The value in this file defines a per-user limit on the number of
+cgroup namespaces that may be created in the user namespace.
+.TP
+.I max_ipc_namespaces
+The value in this file defines a per-user limit on the number of
+ipc namespaces that may be created in the user namespace.
+.TP
+.I max_mnt_namespaces
+The value in this file defines a per-user limit on the number of
+mount namespaces that may be created in the user namespace.
+.TP
+.I max_net_namespaces
+The value in this file defines a per-user limit on the number of
+network namespaces that may be created in the user namespace.
+.TP
+.I max_pid_namespaces
+The value in this file defines a per-user limit on the number of
+PID namespaces that may be created in the user namespace.
+.TP
+.IR max_time_namespaces " (since Linux 5.7)"
+.\" commit eeec26d5da8248ea4e240b8795bb4364213d3247
+The value in this file defines a per-user limit on the number of
+time namespaces that may be created in the user namespace.
+.TP
+.I max_user_namespaces
+The value in this file defines a per-user limit on the number of
+user namespaces that may be created in the user namespace.
+.TP
+.I max_uts_namespaces
+The value in this file defines a per-user limit on the number of
+uts namespaces that may be created in the user namespace.
+.P
+Note the following details about these files:
+.IP \[bu] 3
+The values in these files are modifiable by privileged processes.
+.IP \[bu]
+The values exposed by these files are the limits for the user namespace
+in which the opening process resides.
+.IP \[bu]
+The limits are per-user.
+Each user in the same user namespace
+can create namespaces up to the defined limit.
+.IP \[bu]
+The limits apply to all users, including UID 0.
+.IP \[bu]
+These limits apply in addition to any other per-namespace
+limits (such as those for PID and user namespaces) that may be enforced.
+.IP \[bu]
+Upon encountering these limits,
+.BR clone (2)
+and
+.BR unshare (2)
+fail with the error
+.BR ENOSPC .
+.IP \[bu]
+For the initial user namespace,
+the default value in each of these files is half the limit on the number
+of threads that may be created
+.RI ( /proc/sys/kernel/threads\-max ).
+In all descendant user namespaces, the default value in each file is
+.BR MAXINT .
+.IP \[bu]
+When a namespace is created, the object is also accounted
+against ancestor namespaces.
+More precisely:
+.RS
+.IP \[bu] 3
+Each user namespace has a creator UID.
+.IP \[bu]
+When a namespace is created,
+it is accounted against the creator UIDs in each of the
+ancestor user namespaces,
+and the kernel ensures that the corresponding namespace limit
+for the creator UID in the ancestor namespace is not exceeded.
+.IP \[bu]
+The aforementioned point ensures that creating a new user namespace
+cannot be used as a means to escape the limits in force
+in the current user namespace.
+.RE
+.\"
+.SS Namespace lifetime
+Absent any other factors,
+a namespace is automatically torn down when the last process in
+the namespace terminates or leaves the namespace.
+However, there are a number of other factors that may pin
+a namespace into existence even though it has no member processes.
+These factors include the following:
+.IP \[bu] 3
+An open file descriptor or a bind mount exists for the corresponding
+.IR /proc/ pid /ns/*
+file.
+.IP \[bu]
+The namespace is hierarchical (i.e., a PID or user namespace),
+and has a child namespace.
+.IP \[bu]
+It is a user namespace that owns one or more nonuser namespaces.
+.IP \[bu]
+It is a PID namespace,
+and there is a process that refers to the namespace via a
+.IR /proc/ pid /ns/pid_for_children
+symbolic link.
+.IP \[bu]
+It is a time namespace,
+and there is a process that refers to the namespace via a
+.IR /proc/ pid /ns/time_for_children
+symbolic link.
+.IP \[bu]
+It is an IPC namespace, and a corresponding mount of an
+.I mqueue
+filesystem (see
+.BR mq_overview (7))
+refers to this namespace.
+.IP \[bu]
+It is a PID namespace, and a corresponding mount of a
+.BR proc (5)
+filesystem refers to this namespace.
+.SH EXAMPLES
+See
+.BR clone (2)
+and
+.BR user_namespaces (7).
+.SH SEE ALSO
+.BR nsenter (1),
+.BR readlink (1),
+.BR unshare (1),
+.BR clone (2),
+.BR ioctl_ns (2),
+.BR setns (2),
+.BR unshare (2),
+.BR proc (5),
+.BR capabilities (7),
+.BR cgroup_namespaces (7),
+.BR cgroups (7),
+.BR credentials (7),
+.BR ipc_namespaces (7),
+.BR network_namespaces (7),
+.BR pid_namespaces (7),
+.BR user_namespaces (7),
+.BR uts_namespaces (7),
+.BR lsns (8),
+.BR switch_root (8)
diff --git a/man/man7/netdevice.7 b/man/man7/netdevice.7
new file mode 100644
index 000000000..4722fc257
--- /dev/null
+++ b/man/man7/netdevice.7
@@ -0,0 +1,449 @@
+'\" t
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: netdevice.7,v 1.10 2000/08/17 10:09:54 ak Exp $
+.\"
+.\" Modified, 2004-11-25, mtk, formatting and a few wording fixes
+.\"
+.\" Modified, 2011-11-02, <bidulock@openss7.org>, added many basic
+.\"  but missing ioctls, such as SIOCGIFADDR.
+.\"
+.TH netdevice 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+netdevice \- low-level access to Linux network devices
+.SH SYNOPSIS
+.nf
+.B "#include <sys/ioctl.h>"
+.B "#include <net/if.h>"
+.fi
+.SH DESCRIPTION
+This man page describes the sockets interface which is used to configure
+network devices.
+.P
+Linux supports some standard ioctls to configure network devices.
+They can be used on any socket's file descriptor regardless of the
+family or type.
+Most of them pass an
+.I ifreq
+structure:
+.P
+.in +4n
+.EX
+struct ifreq {
+    char ifr_name[IFNAMSIZ]; /* Interface name */
+    union {
+        struct sockaddr ifr_addr;
+        struct sockaddr ifr_dstaddr;
+        struct sockaddr ifr_broadaddr;
+        struct sockaddr ifr_netmask;
+        struct sockaddr ifr_hwaddr;
+        short           ifr_flags;
+        int             ifr_ifindex;
+        int             ifr_metric;
+        int             ifr_mtu;
+        struct ifmap    ifr_map;
+        char            ifr_slave[IFNAMSIZ];
+        char            ifr_newname[IFNAMSIZ];
+        char           *ifr_data;
+    };
+};
+.EE
+.in
+.P
+.B AF_INET6
+is an exception.
+It passes an
+.I in6_ifreq
+structure:
+.P
+.in +4n
+.EX
+struct in6_ifreq {
+    struct in6_addr     ifr6_addr;
+    u32                 ifr6_prefixlen;
+    int                 ifr6_ifindex; /* Interface index */
+};
+.EE
+.in
+.P
+Normally, the user specifies which device to affect by setting
+.I ifr_name
+to the name of the interface or
+.I ifr6_ifindex
+to the index of the interface.
+All other members of the structure may
+share memory.
+.SS Ioctls
+If an ioctl is marked as privileged, then using it requires an effective
+user ID of 0 or the
+.B CAP_NET_ADMIN
+capability.
+If this is not the case,
+.B EPERM
+will be returned.
+.TP
+.B SIOCGIFNAME
+Given the
+.IR ifr_ifindex ,
+return the name of the interface in
+.IR ifr_name .
+This is the only ioctl which returns its result in
+.IR ifr_name .
+.TP
+.B SIOCGIFINDEX
+Retrieve the interface index of the interface into
+.IR ifr_ifindex .
+.TP
+.B SIOCGIFFLAGS
+.TQ
+.B SIOCSIFFLAGS
+Get or set the active flag word of the device.
+.I ifr_flags
+contains a bit mask of the following values:
+.\" Do not right adjust text blocks in tables
+.na
+.TS
+tab(:);
+c s
+l l.
+Device flags
+IFF_UP:Interface is running.
+IFF_BROADCAST:Valid broadcast address set.
+IFF_DEBUG:Internal debugging flag.
+IFF_LOOPBACK:Interface is a loopback interface.
+IFF_POINTOPOINT:Interface is a point-to-point link.
+IFF_RUNNING:Resources allocated.
+IFF_NOARP:T{
+No arp protocol, L2 destination address not set.
+T}
+IFF_PROMISC:Interface is in promiscuous mode.
+IFF_NOTRAILERS:Avoid use of trailers.
+IFF_ALLMULTI:Receive all multicast packets.
+IFF_MASTER:Master of a load balancing bundle.
+IFF_SLAVE:Slave of a load balancing bundle.
+IFF_MULTICAST:Supports multicast
+IFF_PORTSEL:Is able to select media type via ifmap.
+IFF_AUTOMEDIA:Auto media selection active.
+IFF_DYNAMIC:T{
+The addresses are lost when the interface goes down.
+T}
+IFF_LOWER_UP:Driver signals L1 up (since Linux 2.6.17)
+IFF_DORMANT:Driver signals dormant (since Linux 2.6.17)
+IFF_ECHO:Echo sent packets (since Linux 2.6.25)
+.TE
+.ad
+.P
+Setting the active flag word is a privileged operation, but any
+process may read it.
+.TP
+.B SIOCGIFPFLAGS
+.TQ
+.B SIOCSIFPFLAGS
+Get or set extended (private) flags for the device.
+.I ifr_flags
+contains a bit mask of the following values:
+.TS
+tab(:);
+c s
+l l.
+Private flags
+IFF_802_1Q_VLAN:Interface is 802.1Q VLAN device.
+IFF_EBRIDGE:Interface is Ethernet bridging device.
+IFF_SLAVE_INACTIVE:Interface is inactive bonding slave.
+IFF_MASTER_8023AD:Interface is 802.3ad bonding master.
+IFF_MASTER_ALB:Interface is balanced-alb bonding master.
+IFF_BONDING:Interface is a bonding master or slave.
+IFF_SLAVE_NEEDARP:Interface needs ARPs for validation.
+IFF_ISATAP:Interface is RFC4214 ISATAP interface.
+.TE
+.P
+Setting the extended (private) interface flags is a privileged operation.
+.TP
+.B SIOCGIFADDR
+.TQ
+.B SIOCSIFADDR
+.TQ
+.B SIOCDIFADDR
+Get, set, or delete the address of the device using
+.IR ifr_addr ,
+or
+.I ifr6_addr
+with
+.IR ifr6_prefixlen .
+Setting or deleting the interface address is a privileged operation.
+For compatibility,
+.B SIOCGIFADDR
+returns only
+.B AF_INET
+addresses,
+.B SIOCSIFADDR
+accepts
+.B AF_INET
+and
+.B AF_INET6
+addresses, and
+.B SIOCDIFADDR
+deletes only
+.B AF_INET6
+addresses.
+A
+.B AF_INET
+address can be deleted by setting it to zero via
+.BR SIOCSIFADDR .
+.TP
+.B SIOCGIFDSTADDR
+.TQ
+.B SIOCSIFDSTADDR
+Get or set the destination address of a point-to-point device using
+.IR ifr_dstaddr .
+For compatibility, only
+.B AF_INET
+addresses are accepted or returned.
+Setting the destination address is a privileged operation.
+.TP
+.B SIOCGIFBRDADDR
+.TQ
+.B SIOCSIFBRDADDR
+Get or set the broadcast address for a device using
+.IR ifr_brdaddr .
+For compatibility, only
+.B AF_INET
+addresses are accepted or returned.
+Setting the broadcast address is a privileged operation.
+.TP
+.B SIOCGIFNETMASK
+.TQ
+.B SIOCSIFNETMASK
+Get or set the network mask for a device using
+.IR ifr_netmask .
+For compatibility, only
+.B AF_INET
+addresses are accepted or returned.
+Setting the network mask is a privileged operation.
+.TP
+.B SIOCGIFMETRIC
+.TQ
+.B SIOCSIFMETRIC
+Get or set the metric of the device using
+.IR ifr_metric .
+This is currently not implemented; it sets
+.I ifr_metric
+to 0 if you attempt to read it and returns
+.B EOPNOTSUPP
+if you attempt to set it.
+.TP
+.B SIOCGIFMTU
+.TQ
+.B SIOCSIFMTU
+Get or set the MTU (Maximum Transfer Unit) of a device using
+.IR ifr_mtu .
+Setting the MTU is a privileged operation.
+Setting the MTU to
+too small values may cause kernel crashes.
+.TP
+.B SIOCGIFHWADDR
+.TQ
+.B SIOCSIFHWADDR
+Get or set the hardware address of a device using
+.IR ifr_hwaddr .
+The hardware address is specified in a struct
+.IR sockaddr .
+.I sa_family
+contains the ARPHRD_* device type,
+.I sa_data
+the L2 hardware address starting from byte 0.
+Setting the hardware address is a privileged operation.
+.TP
+.B SIOCSIFHWBROADCAST
+Set the hardware broadcast address of a device from
+.IR ifr_hwaddr .
+This is a privileged operation.
+.TP
+.B SIOCGIFMAP
+.TQ
+.B SIOCSIFMAP
+Get or set the interface's hardware parameters using
+.IR ifr_map .
+Setting the parameters is a privileged operation.
+.IP
+.in +4n
+.EX
+struct ifmap {
+    unsigned long   mem_start;
+    unsigned long   mem_end;
+    unsigned short  base_addr;
+    unsigned char   irq;
+    unsigned char   dma;
+    unsigned char   port;
+};
+.EE
+.in
+.IP
+The interpretation of the ifmap structure depends on the device driver
+and the architecture.
+.TP
+.B SIOCADDMULTI
+.TQ
+.B SIOCDELMULTI
+Add an address to or delete an address from the device's link layer
+multicast filters using
+.IR ifr_hwaddr .
+These are privileged operations.
+See also
+.BR packet (7)
+for an alternative.
+.TP
+.B SIOCGIFTXQLEN
+.TQ
+.B SIOCSIFTXQLEN
+Get or set the transmit queue length of a device using
+.IR ifr_qlen .
+Setting the transmit queue length is a privileged operation.
+.TP
+.B SIOCSIFNAME
+Changes the name of the interface specified in
+.I ifr_name
+to
+.IR ifr_newname .
+This is a privileged operation.
+It is allowed only when the interface
+is not up.
+.TP
+.B SIOCGIFCONF
+Return a list of interface (network layer) addresses.
+This currently
+means only addresses of the
+.B AF_INET
+(IPv4) family for compatibility.
+Unlike the others, this ioctl passes an
+.I ifconf
+structure:
+.IP
+.in +4n
+.EX
+struct ifconf {
+    int               ifc_len; /* size of buffer */
+    union {
+        char         *ifc_buf; /* buffer address */
+        struct ifreq *ifc_req; /* array of structures */
+    };
+};
+.EE
+.in
+.IP
+If
+.I ifc_req
+is NULL,
+.B SIOCGIFCONF
+returns the necessary buffer size in bytes
+for receiving all available addresses in
+.IR ifc_len .
+Otherwise,
+.I ifc_req
+contains a pointer to an array of
+.I ifreq
+structures to be filled with all currently active L3 interface addresses.
+.I ifc_len
+contains the size of the array in bytes.
+Within each
+.I ifreq
+structure,
+.I ifr_name
+will receive the interface name, and
+.I ifr_addr
+the address.
+The actual number of bytes transferred is returned in
+.IR ifc_len .
+.IP
+If the size specified by
+.I ifc_len
+is insufficient to store all the addresses,
+the kernel will skip the exceeding ones and return success.
+There is no reliable way of detecting this condition once it has occurred.
+It is therefore recommended to either determine the necessary buffer size
+beforehand by calling
+.B SIOCGIFCONF
+with
+.I ifc_req
+set to NULL, or to retry the call with a bigger buffer whenever
+.I ifc_len
+upon return differs by less than
+.I sizeof(struct ifreq)
+from its original value.
+.IP
+If an error occurs accessing the
+.I ifconf
+or
+.I ifreq
+structures,
+.B EFAULT
+will be returned.
+.\" Slaving isn't supported in Linux 2.2
+.\" .
+.\" .TP
+.\" .B SIOCGIFSLAVE
+.\" .TQ
+.\" .B SIOCSIFSLAVE
+.\" Get or set the slave device using
+.\" .IR ifr_slave .
+.\" Setting the slave device is a privileged operation.
+.\" .P
+.\" FIXME . add amateur radio stuff.
+.P
+Most protocols support their own ioctls to configure protocol-specific
+interface options.
+See the protocol man pages for a description.
+For configuring IP addresses, see
+.BR ip (7).
+.P
+In addition, some devices support private ioctls.
+These are not described here.
+.SH NOTES
+.B SIOCGIFCONF
+and the other ioctls that accept or return only
+.B AF_INET
+socket addresses
+are IP-specific and perhaps should rather be documented in
+.BR ip (7).
+.P
+The names of interfaces with no addresses or that don't have the
+.B IFF_RUNNING
+flag set can be found via
+.IR /proc/net/dev .
+.P
+.B AF_INET6
+IPv6 addresses can be read from
+.I /proc/net/if_inet6
+or via
+.BR rtnetlink (7).
+Adding a new IPv6 address and deleting an existing IPv6 address
+can be done via
+.B SIOCSIFADDR
+and
+.B SIOCDIFADDR
+or via
+.BR rtnetlink (7).
+Retrieving or changing destination IPv6 addresses of a point-to-point
+interface is possible only via
+.BR rtnetlink (7).
+.SH BUGS
+glibc 2.1 is missing the
+.I ifr_newname
+macro in
+.IR <net/if.h> .
+Add the following to your program as a workaround:
+.P
+.in +4n
+.EX
+#ifndef ifr_newname
+#define ifr_newname     ifr_ifru.ifru_slave
+#endif
+.EE
+.in
+.SH SEE ALSO
+.BR proc (5),
+.BR capabilities (7),
+.BR ip (7),
+.BR rtnetlink (7)
diff --git a/man/man7/netlink.7 b/man/man7/netlink.7
new file mode 100644
index 000000000..4198bf157
--- /dev/null
+++ b/man/man7/netlink.7
@@ -0,0 +1,611 @@
+'\" t
+.\" This man page is Copyright (c) 1998 by Andi Kleen.
+.\"
+.\" SPDX-License-Identifier: GPL-1.0-or-later
+.\"
+.\" Based on the original comments from Alexey Kuznetsov
+.\" Modified 2005-12-27 by Hasso Tepper <hasso@estpak.ee>
+.\" $Id: netlink.7,v 1.8 2000/06/22 13:23:00 ak Exp $
+.TH netlink 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+netlink \- communication between kernel and user space (AF_NETLINK)
+.SH SYNOPSIS
+.nf
+.B #include <asm/types.h>
+.B #include <sys/socket.h>
+.B #include <linux/netlink.h>
+.P
+.BI "netlink_socket = socket(AF_NETLINK, " socket_type ", " netlink_family );
+.fi
+.SH DESCRIPTION
+Netlink is used to transfer information between the kernel and
+user-space processes.
+It consists of a standard sockets-based interface for user space
+processes and an internal kernel API for kernel modules.
+The internal kernel interface is not documented in this manual page.
+There is also an obsolete netlink interface
+via netlink character devices; this interface is not documented here
+and is provided only for backward compatibility.
+.P
+Netlink is a datagram-oriented service.
+Both
+.B SOCK_RAW
+and
+.B SOCK_DGRAM
+are valid values for
+.IR socket_type .
+However, the netlink protocol does not distinguish between datagram
+and raw sockets.
+.P
+.I netlink_family
+selects the kernel module or netlink group to communicate with.
+The currently assigned netlink families are:
+.TP
+.B NETLINK_ROUTE
+Receives routing and link updates and may be used to modify the routing
+tables (both IPv4 and IPv6), IP addresses, link parameters,
+neighbor setups, queueing disciplines, traffic classes, and
+packet classifiers (see
+.BR rtnetlink (7)).
+.TP
+.BR NETLINK_W1 " (Linux 2.6.13 to Linux 2.16.17)"
+Messages from 1-wire subsystem.
+.TP
+.B NETLINK_USERSOCK
+Reserved for user-mode socket protocols.
+.TP
+.BR NETLINK_FIREWALL " (up to and including Linux 3.4)"
+.\" removed by commit d16cf20e2f2f13411eece7f7fb72c17d141c4a84
+Transport IPv4 packets from netfilter to user space.
+Used by
+.I ip_queue
+kernel module.
+After a long period of being declared obsolete (in favor of the more advanced
+.I nfnetlink_queue
+feature),
+.B NETLINK_FIREWALL
+was removed in Linux 3.5.
+.TP
+.BR NETLINK_SOCK_DIAG " (since Linux 3.3)"
+.\" commit 7f1fb60c4fc9fb29fbb406ac8c4cfb4e59e168d6
+Query information about sockets of various protocol families from the kernel
+(see
+.BR sock_diag (7)).
+.TP
+.BR NETLINK_INET_DIAG " (since Linux 2.6.14)"
+An obsolete synonym for
+.BR NETLINK_SOCK_DIAG .
+.TP
+.BR NETLINK_NFLOG " (up to and including Linux 3.16)"
+Netfilter/iptables ULOG.
+.TP
+.B NETLINK_XFRM
+.\" FIXME More details on NETLINK_XFRM needed.
+IPsec.
+.TP
+.BR NETLINK_SELINUX " (since Linux 2.6.4)"
+SELinux event notifications.
+.TP
+.BR NETLINK_ISCSI " (since Linux 2.6.15)"
+.\" FIXME More details on NETLINK_ISCSI needed.
+Open-iSCSI.
+.TP
+.BR NETLINK_AUDIT " (since Linux 2.6.6)"
+.\" FIXME More details on NETLINK_AUDIT needed.
+Auditing.
+.TP
+.BR NETLINK_FIB_LOOKUP " (since Linux 2.6.13)"
+.\" FIXME More details on NETLINK_FIB_LOOKUP needed.
+Access to FIB lookup from user space.
+.TP
+.BR NETLINK_CONNECTOR " (since Linux 2.6.14)"
+Kernel connector.
+See
+.I Documentation/driver\-api/connector.rst
+(or
+.I /Documentation/connector/connector.*
+.\" commit baa293e9544bea71361950d071579f0e4d5713ed
+in Linux 5.2 and earlier)
+in the Linux kernel source tree for further information.
+.TP
+.BR NETLINK_NETFILTER " (since Linux 2.6.14)"
+.\" FIXME More details on NETLINK_NETFILTER needed.
+Netfilter subsystem.
+.TP
+.BR NETLINK_SCSITRANSPORT " (since Linux 2.6.19)"
+.\" commit 84314fd4740ad73550c76dee4a9578979d84af48
+.\" FIXME More details on NETLINK_SCSITRANSPORT needed.
+SCSI Transports.
+.TP
+.BR NETLINK_RDMA " (since Linux 3.0)"
+.\" commit b2cbae2c248776d81cc265ff7d48405b6a4cc463
+.\" FIXME More details on NETLINK_RDMA needed.
+Infiniband RDMA.
+.TP
+.BR NETLINK_IP6_FW " (up to and including Linux 3.4)"
+Transport IPv6 packets from netfilter to user space.
+Used by
+.I ip6_queue
+kernel module.
+.TP
+.B NETLINK_DNRTMSG
+DECnet routing messages.
+.TP
+.BR NETLINK_KOBJECT_UEVENT " (since Linux 2.6.10)"
+.\" FIXME More details on NETLINK_KOBJECT_UEVENT needed.
+Kernel messages to user space.
+.TP
+.BR NETLINK_GENERIC " (since Linux 2.6.15)"
+Generic netlink family for simplified netlink usage.
+.TP
+.BR NETLINK_CRYPTO " (since Linux 3.2)"
+.\" commit a38f7907b926e4c6c7d389ad96cc38cec2e5a9e9
+.\" Author: Steffen Klassert <steffen.klassert@secunet.com>
+Netlink interface to request information about ciphers registered
+with the kernel crypto API as well as allow configuration of the
+kernel crypto API.
+.P
+Netlink messages consist of a byte stream with one or multiple
+.I nlmsghdr
+headers and associated payload.
+The byte stream should be accessed only with the standard
+.B NLMSG_*
+macros.
+See
+.BR netlink (3)
+for further information.
+.P
+In multipart messages (multiple
+.I nlmsghdr
+headers with associated payload in one byte stream) the first and all
+following headers have the
+.B NLM_F_MULTI
+flag set, except for the last header which has the type
+.BR NLMSG_DONE .
+.P
+After each
+.I nlmsghdr
+the payload follows.
+.P
+.in +4n
+.EX
+struct nlmsghdr {
+    __u32 nlmsg_len;    /* Length of message including header */
+    __u16 nlmsg_type;   /* Type of message content */
+    __u16 nlmsg_flags;  /* Additional flags */
+    __u32 nlmsg_seq;    /* Sequence number */
+    __u32 nlmsg_pid;    /* Sender port ID */
+};
+.EE
+.in
+.P
+.I nlmsg_type
+can be one of the standard message types:
+.B NLMSG_NOOP
+message is to be ignored,
+.B NLMSG_ERROR
+message signals an error and the payload contains an
+.I nlmsgerr
+structure,
+.B NLMSG_DONE
+message terminates a multipart message.
+Error messages get the
+original request appended, unless the user requests to cap the
+error message, and get extra error data if requested.
+.P
+.in +4n
+.EX
+struct nlmsgerr {
+    int error;        /* Negative errno or 0 for acknowledgements */
+    struct nlmsghdr msg;  /* Message header that caused the error */
+    /*
+     * followed by the message contents
+     * unless NETLINK_CAP_ACK was set
+     * or the ACK indicates success (error == 0).
+     * For example Generic Netlink message with attributes.
+     * message length is aligned with NLMSG_ALIGN()
+     */
+    /*
+     * followed by TLVs defined in enum nlmsgerr_attrs
+     * if NETLINK_EXT_ACK was set
+     */
+};
+.EE
+.in
+.P
+A netlink family usually specifies more message types, see the
+appropriate manual pages for that, for example,
+.BR rtnetlink (7)
+for
+.BR NETLINK_ROUTE .
+.TS
+tab(:);
+l s
+lB lx.
+Standard flag bits in \fInlmsg_flags\fP
+_
+NLM_F_REQUEST:T{
+Must be set on all request messages.
+T}
+NLM_F_MULTI:T{
+The message is part of a multipart message terminated by
+.BR NLMSG_DONE .
+T}
+NLM_F_ACK:T{
+Request for an acknowledgement on success.
+T}
+NLM_F_ECHO:T{
+Echo this request.
+T}
+.TE
+.\" No right adjustment for text blocks in tables
+.TS
+tab(:);
+l s
+lB lx.
+Additional flag bits for GET requests
+_
+NLM_F_ROOT:T{
+Return the complete table instead of a single entry.
+T}
+NLM_F_MATCH:T{
+Return all entries matching criteria passed in message content.
+Not implemented yet.
+T}
+NLM_F_ATOMIC:T{
+Return an atomic snapshot of the table.
+T}
+NLM_F_DUMP:T{
+Convenience macro; equivalent to
+(NLM_F_ROOT|NLM_F_MATCH).
+T}
+.TE
+.\" FIXME NLM_F_ATOMIC is not used anymore?
+.P
+Note that
+.B NLM_F_ATOMIC
+requires the
+.B CAP_NET_ADMIN
+capability or an effective UID of 0.
+.TS
+tab(:);
+l s
+lB lx.
+Additional flag bits for NEW requests
+_
+NLM_F_REPLACE:T{
+Replace existing matching object.
+T}
+NLM_F_EXCL:T{
+Don't replace if the object already exists.
+T}
+NLM_F_CREATE:T{
+Create object if it doesn't already exist.
+T}
+NLM_F_APPEND:T{
+Add to the end of the object list.
+T}
+.TE
+.P
+.I nlmsg_seq
+and
+.I nlmsg_pid
+are used to track messages.
+.I nlmsg_pid
+shows the origin of the message.
+Note that there isn't a 1:1 relationship between
+.I nlmsg_pid
+and the PID of the process if the message originated from a netlink
+socket.
+See the
+.B ADDRESS FORMATS
+section for further information.
+.P
+Both
+.I nlmsg_seq
+and
+.I nlmsg_pid
+.\" FIXME Explain more about nlmsg_seq and nlmsg_pid.
+are opaque to netlink core.
+.P
+Netlink is not a reliable protocol.
+It tries its best to deliver a message to its destination(s),
+but may drop messages when an out-of-memory condition or
+other error occurs.
+For reliable transfer the sender can request an
+acknowledgement from the receiver by setting the
+.B NLM_F_ACK
+flag.
+An acknowledgement is an
+.B NLMSG_ERROR
+packet with the error field set to 0.
+The application must generate acknowledgements for
+received messages itself.
+The kernel tries to send an
+.B NLMSG_ERROR
+message for every failed packet.
+A user process should follow this convention too.
+.P
+However, reliable transmissions from kernel to user are impossible
+in any case.
+The kernel can't send a netlink message if the socket buffer is full:
+the message will be dropped and the kernel and the user-space process will
+no longer have the same view of kernel state.
+It is up to the application to detect when this happens (via the
+.B ENOBUFS
+error returned by
+.BR recvmsg (2))
+and resynchronize.
+.SS Address formats
+The
+.I sockaddr_nl
+structure describes a netlink client in user space or in the kernel.
+A
+.I sockaddr_nl
+can be either unicast (only sent to one peer) or sent to
+netlink multicast groups
+.RI ( nl_groups
+not equal 0).
+.P
+.in +4n
+.EX
+struct sockaddr_nl {
+    sa_family_t     nl_family;  /* AF_NETLINK */
+    unsigned short  nl_pad;     /* Zero */
+    pid_t           nl_pid;     /* Port ID */
+    __u32           nl_groups;  /* Multicast groups mask */
+};
+.EE
+.in
+.P
+.I nl_pid
+is the unicast address of netlink socket.
+It's always 0 if the destination is in the kernel.
+For a user-space process,
+.I nl_pid
+is usually the PID of the process owning the destination socket.
+However,
+.I nl_pid
+identifies a netlink socket, not a process.
+If a process owns several netlink
+sockets, then
+.I nl_pid
+can be equal to the process ID only for at most one socket.
+There are two ways to assign
+.I nl_pid
+to a netlink socket.
+If the application sets
+.I nl_pid
+before calling
+.BR bind (2),
+then it is up to the application to make sure that
+.I nl_pid
+is unique.
+If the application sets it to 0, the kernel takes care of assigning it.
+The kernel assigns the process ID to the first netlink socket the process
+opens and assigns a unique
+.I nl_pid
+to every netlink socket that the process subsequently creates.
+.P
+.I nl_groups
+is a bit mask with every bit representing a netlink group number.
+Each netlink family has a set of 32 multicast groups.
+When
+.BR bind (2)
+is called on the socket, the
+.I nl_groups
+field in the
+.I sockaddr_nl
+should be set to a bit mask of the groups which it wishes to listen to.
+The default value for this field is zero which means that no multicasts
+will be received.
+A socket may multicast messages to any of the multicast groups by setting
+.I nl_groups
+to a bit mask of the groups it wishes to send to when it calls
+.BR sendmsg (2)
+or does a
+.BR connect (2).
+Only processes with an effective UID of 0 or the
+.B CAP_NET_ADMIN
+capability may send or listen to a netlink multicast group.
+Since Linux 2.6.13,
+.\" commit d629b836d151d43332492651dd841d32e57ebe3b
+messages can't be broadcast to multiple groups.
+Any replies to a message received for a multicast group should be
+sent back to the sending PID and the multicast group.
+Some Linux kernel subsystems may additionally allow other users
+to send and/or receive messages.
+As at Linux 3.0, the
+.BR NETLINK_KOBJECT_UEVENT ,
+.BR NETLINK_GENERIC ,
+.BR NETLINK_ROUTE ,
+and
+.B NETLINK_SELINUX
+groups allow other users to receive messages.
+No groups allow other users to send messages.
+.SS Socket options
+To set or get a netlink socket option, call
+.BR getsockopt (2)
+to read or
+.BR setsockopt (2)
+to write the option with the option level argument set to
+.BR SOL_NETLINK .
+Unless otherwise noted,
+.I optval
+is a pointer to an
+.IR int .
+.TP
+.BR NETLINK_PKTINFO " (since Linux 2.6.14)"
+.\"	commit 9a4595bc7e67962f13232ee55a64e063062c3a99
+.\"	Author: Patrick McHardy <kaber@trash.net>
+Enable
+.B nl_pktinfo
+control messages for received packets to get the extended
+destination group number.
+.TP
+.B NETLINK_ADD_MEMBERSHIP
+.TQ
+.BR NETLINK_DROP_MEMBERSHIP " (since Linux 2.6.14)"
+.\"	commit 9a4595bc7e67962f13232ee55a64e063062c3a99
+.\"	Author: Patrick McHardy <kaber@trash.net>
+Join/leave a group specified by
+.IR optval .
+.TP
+.BR NETLINK_LIST_MEMBERSHIPS " (since Linux 4.2)"
+.\"	commit b42be38b2778eda2237fc759e55e3b698b05b315
+.\"	Author: David Herrmann <dh.herrmann@gmail.com>
+Retrieve all groups a socket is a member of.
+.I optval
+is a pointer to
+.B __u32
+and
+.I optlen
+is the size of the array.
+The array is filled with the full membership set of the
+socket, and the required array size is returned in
+.IR optlen .
+.TP
+.BR NETLINK_BROADCAST_ERROR " (since Linux 2.6.30)"
+.\"	commit be0c22a46cfb79ab2342bb28fde99afa94ef868e
+.\"	Author: Pablo Neira Ayuso <pablo@netfilter.org>
+When not set,
+.B netlink_broadcast()
+only reports
+.B ESRCH
+errors and silently ignore
+.B ENOBUFS
+errors.
+.TP
+.BR NETLINK_NO_ENOBUFS " (since Linux 2.6.30)"
+.\"	commit 38938bfe3489394e2eed5e40c9bb8f66a2ce1405
+.\"	Author: Pablo Neira Ayuso <pablo@netfilter.org>
+This flag can be used by unicast and broadcast listeners to avoid receiving
+.B ENOBUFS
+errors.
+.TP
+.BR NETLINK_LISTEN_ALL_NSID " (since Linux 4.2)"
+.\"	commit 59324cf35aba5336b611074028777838a963d03b
+.\"	Author: Nicolas Dichtel <nicolas.dichtel@6wind.com>
+When set, this socket will receive netlink notifications from
+all network namespaces that have an
+.I nsid
+assigned into the network namespace where the socket has been opened.
+The
+.I nsid
+is sent to user space via an ancillary data.
+.TP
+.BR NETLINK_CAP_ACK " (since Linux 4.3)"
+.\"	commit 0a6a3a23ea6efde079a5b77688541a98bf202721
+.\"	Author: Christophe Ricard <christophe.ricard@gmail.com>
+The kernel may fail to allocate the necessary room for the acknowledgement
+message back to user space.
+This option trims off the payload of the original netlink message.
+The netlink message header is still included, so the user can guess from the
+sequence number which message triggered the acknowledgement.
+.SH VERSIONS
+The socket interface to netlink first appeared Linux 2.2.
+.P
+Linux 2.0 supported a more primitive device-based netlink interface
+(which is still available as a compatibility option).
+This obsolete interface is not described here.
+.SH NOTES
+It is often better to use netlink via
+.I libnetlink
+or
+.I libnl
+than via the low-level kernel interface.
+.SH BUGS
+This manual page is not complete.
+.SH EXAMPLES
+The following example creates a
+.B NETLINK_ROUTE
+netlink socket which will listen to the
+.B RTMGRP_LINK
+(network interface create/delete/up/down events) and
+.B RTMGRP_IPV4_IFADDR
+(IPv4 addresses add/delete events) multicast groups.
+.P
+.in +4n
+.EX
+struct sockaddr_nl sa;
+\&
+memset(&sa, 0, sizeof(sa));
+sa.nl_family = AF_NETLINK;
+sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR;
+\&
+fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+bind(fd, (struct sockaddr *) &sa, sizeof(sa));
+.EE
+.in
+.P
+The next example demonstrates how to send a netlink message to the
+kernel (pid 0).
+Note that the application must take care of message sequence numbers
+in order to reliably track acknowledgements.
+.P
+.in +4n
+.EX
+struct nlmsghdr *nh;    /* The nlmsghdr with payload to send */
+struct sockaddr_nl sa;
+struct iovec iov = { nh, nh\->nlmsg_len };
+struct msghdr msg;
+\&
+msg = { &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
+memset(&sa, 0, sizeof(sa));
+sa.nl_family = AF_NETLINK;
+nh\->nlmsg_pid = 0;
+nh\->nlmsg_seq = ++sequence_number;
+/* Request an ack from kernel by setting NLM_F_ACK */
+nh\->nlmsg_flags |= NLM_F_ACK;
+\&
+sendmsg(fd, &msg, 0);
+.EE
+.in
+.P
+And the last example is about reading netlink message.
+.P
+.in +4n
+.EX
+int len;
+/* 8192 to avoid message truncation on platforms with
+   page size > 4096 */
+struct nlmsghdr buf[8192/sizeof(struct nlmsghdr)];
+struct iovec iov = { buf, sizeof(buf) };
+struct sockaddr_nl sa;
+struct msghdr msg;
+struct nlmsghdr *nh;
+\&
+msg = { &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
+len = recvmsg(fd, &msg, 0);
+\&
+for (nh = (struct nlmsghdr *) buf; NLMSG_OK (nh, len);
+     nh = NLMSG_NEXT (nh, len)) {
+    /* The end of multipart message */
+    if (nh\->nlmsg_type == NLMSG_DONE)
+        return;
+\&
+    if (nh\->nlmsg_type == NLMSG_ERROR)
+        /* Do some error handling */
+    ...
+\&
+    /* Continue with parsing payload */
+    ...
+}
+.EE
+.in
+.SH SEE ALSO
+.BR cmsg (3),
+.BR netlink (3),
+.BR capabilities (7),
+.BR rtnetlink (7),
+.BR sock_diag (7)
+.P
+.UR ftp://ftp.inr.ac.ru\:/ip\-routing\:/iproute2*
+information about libnetlink
+.UE
+.P
+.UR http://www.infradead.org\:/\[ti]tgr\:/libnl/
+information about libnl
+.UE
+.P
+RFC 3549 "Linux Netlink as an IP Services Protocol"
diff --git a/man/man7/network_namespaces.7 b/man/man7/network_namespaces.7
new file mode 100644
index 000000000..92ebc32ae
--- /dev/null
+++ b/man/man7/network_namespaces.7
@@ -0,0 +1,62 @@
+.\" Copyright (c) 2017 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH network_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+network_namespaces \- overview of Linux network namespaces
+.SH DESCRIPTION
+Network namespaces provide isolation of the system resources associated
+with networking: network devices, IPv4 and IPv6 protocol stacks,
+IP routing tables, firewall rules, the
+.I /proc/net
+directory (which is a symbolic link to
+.IR /proc/ pid /net ),
+the
+.I /sys/class/net
+directory, various files under
+.IR /proc/sys/net ,
+port numbers (sockets), and so on.
+In addition,
+network namespaces isolate the UNIX domain abstract socket namespace (see
+.BR unix (7)).
+.P
+A physical network device can live in exactly one
+network namespace.
+When a network namespace is freed
+(i.e., when the last process in the namespace terminates),
+its physical network devices are moved back to the
+initial network namespace
+(not to the namespace of the parent of the process).
+.P
+A virtual network
+.RB ( veth (4))
+device pair provides a pipe-like abstraction
+that can be used to create tunnels between network namespaces,
+and can be used to create a bridge to a physical network device
+in another namespace.
+When a namespace is freed, the
+.BR veth (4)
+devices that it contains are destroyed.
+.P
+Use of network namespaces requires a kernel that is configured with the
+.B CONFIG_NET_NS
+option.
+.\" FIXME .SH EXAMPLES
+.SH SEE ALSO
+.BR nsenter (1),
+.BR unshare (1),
+.BR clone (2),
+.BR veth (4),
+.BR proc (5),
+.BR sysfs (5),
+.BR namespaces (7),
+.BR user_namespaces (7),
+.BR brctl (8),
+.BR ip (8),
+.BR ip\-address (8),
+.BR ip\-link (8),
+.BR ip\-netns (8),
+.BR iptables (8),
+.BR ovs\-vsctl (8)
diff --git a/man/man7/nptl.7 b/man/man7/nptl.7
new file mode 100644
index 000000000..1bff274d3
--- /dev/null
+++ b/man/man7/nptl.7
@@ -0,0 +1,112 @@
+.\" Copyright (c) 2015 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH nptl 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nptl \- Native POSIX Threads Library
+.SH DESCRIPTION
+NPTL (Native POSIX Threads Library)
+is the GNU C library POSIX threads implementation that is used on modern
+Linux systems.
+.\"
+.SS NPTL and signals
+NPTL makes internal use of the first two real-time signals
+(signal numbers 32 and 33).
+One of these signals is used to support thread cancelation and POSIX timers
+(see
+.BR timer_create (2));
+the other is used as part of a mechanism that ensures all threads in
+a process always have the same UIDs and GIDs, as required by POSIX.
+These signals cannot be used in applications.
+.P
+To prevent accidental use of these signals in applications,
+which might interfere with the operation of the NPTL implementation,
+various glibc library functions and system call wrapper functions
+attempt to hide these signals from applications,
+as follows:
+.IP \[bu] 3
+.B SIGRTMIN
+is defined with the value 34 (rather than 32).
+.IP \[bu]
+The
+.BR sigwaitinfo (2),
+.BR sigtimedwait (2),
+and
+.BR sigwait (3)
+interfaces silently ignore requests to wait for these two signals
+if they are specified in the signal set argument of these calls.
+.IP \[bu]
+The
+.BR sigprocmask (2)
+and
+.BR pthread_sigmask (3)
+interfaces silently ignore attempts to block these two signals.
+.IP \[bu]
+The
+.BR sigaction (2),
+.BR pthread_kill (3),
+and
+.BR pthread_sigqueue (3)
+interfaces fail with the error
+.B EINVAL
+(indicating an invalid signal number) if these signals are specified.
+.IP \[bu]
+.BR sigfillset (3)
+does not include these two signals when it creates a full signal set.
+.\"
+.SS NPTL and process credential changes
+At the Linux kernel level,
+credentials (user and group IDs) are a per-thread attribute.
+However, POSIX requires that all of the POSIX threads in a process
+have the same credentials.
+To accommodate this requirement,
+the NPTL implementation wraps all of the system calls that
+change process credentials with functions that,
+in addition to invoking the underlying system call,
+arrange for all other threads in the process to also change their credentials.
+.P
+The implementation of each of these system calls involves the use of
+a real-time signal that is sent (using
+.BR tgkill (2))
+to each of the other threads that must change its credentials.
+Before sending these signals, the thread that is changing credentials
+saves the new credential(s) and records the system call being employed
+in a global buffer.
+A signal handler in the receiving thread(s) fetches this information and
+then uses the same system call to change its credentials.
+.P
+Wrapper functions employing this technique are provided for
+.BR setgid (2),
+.BR setuid (2),
+.BR setegid (2),
+.BR seteuid (2),
+.BR setregid (2),
+.BR setreuid (2),
+.BR setresgid (2),
+.BR setresuid (2),
+and
+.BR setgroups (2).
+.\" FIXME .
+.\" Maybe say something about vfork() not being serialized wrt set*id() APIs?
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=14749
+.SH STANDARDS
+For details of the conformance of NPTL to the POSIX standard, see
+.BR pthreads (7).
+.SH NOTES
+POSIX says
+.\" See POSIX.1-2008 specification of pthread_mutexattr_init()
+that any thread in any process with access to the memory
+containing a process-shared
+.RB ( PTHREAD_PROCESS_SHARED )
+mutex can operate on that mutex.
+However, on 64-bit x86 systems, the mutex definition for x86-64
+is incompatible with the mutex definition for i386,
+.\" See sysdeps/x86/bits/pthreadtypes.h
+meaning that 32-bit and 64-bit binaries can't share mutexes on x86-64 systems.
+.SH SEE ALSO
+.BR credentials (7),
+.BR pthreads (7),
+.BR signal (7),
+.BR standards (7)
diff --git a/man/man7/numa.7 b/man/man7/numa.7
new file mode 100644
index 000000000..ac3e38112
--- /dev/null
+++ b/man/man7/numa.7
@@ -0,0 +1,170 @@
+.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\" and Copyright 2003,2004 Andi Kleen, SuSE Labs.
+.\" numa_maps material Copyright (c) 2005 Silicon Graphics Incorporated.
+.\"     Christoph Lameter, <cl@linux-foundation.org>.
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH numa 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+numa \- overview of Non-Uniform Memory Architecture
+.SH DESCRIPTION
+Non-Uniform Memory Access (NUMA) refers to multiprocessor systems
+whose memory is divided into multiple memory nodes.
+The access time of a memory node depends on
+the relative locations of the accessing CPU and the accessed node.
+(This contrasts with a symmetric multiprocessor system,
+where the access time for all of the memory is the same for all CPUs.)
+Normally, each CPU on a NUMA system has a local memory node whose
+contents can be accessed faster than the memory in
+the node local to another CPU
+or the memory on a bus shared by all CPUs.
+.SS NUMA system calls
+The Linux kernel implements the following NUMA-related system calls:
+.BR get_mempolicy (2),
+.BR mbind (2),
+.BR migrate_pages (2),
+.BR move_pages (2),
+and
+.BR set_mempolicy (2).
+However, applications should normally use the interface provided by
+.IR libnuma ;
+see "Library Support" below.
+.SS \fI/proc/\fPpid\fI/numa_maps\fP  (since Linux 2.6.14)
+.\" See also Changelog-2.6.14
+This file displays information about a process's
+NUMA memory policy and allocation.
+.P
+Each line contains information about a memory range used by the process,
+displaying\[em]among other information\[em]the effective memory policy for
+that memory range and on which nodes the pages have been allocated.
+.P
+.I numa_maps
+is a read-only file.
+When
+.IR /proc/ pid /numa_maps
+is read, the kernel will scan the virtual address space of the
+process and report how memory is used.
+One line is displayed for each unique memory range of the process.
+.P
+The first field of each line shows the starting address of the memory range.
+This field allows a correlation with the contents of the
+.IR /proc/ pid /maps
+file,
+which contains the end address of the range and other information,
+such as the access permissions and sharing.
+.P
+The second field shows the memory policy currently in effect for the
+memory range.
+Note that the effective policy is not necessarily the policy
+installed by the process for that memory range.
+Specifically, if the process installed a "default" policy for that range,
+the effective policy for that range will be the process policy,
+which may or may not be "default".
+.P
+The rest of the line contains information about the pages allocated in
+the memory range, as follows:
+.TP
+.I N<node>=<nr_pages>
+The number of pages allocated on
+.IR <node> .
+.I <nr_pages>
+includes only pages currently mapped by the process.
+Page migration and memory reclaim may have temporarily unmapped pages
+associated with this memory range.
+These pages may show up again only after the process has
+attempted to reference them.
+If the memory range represents a shared memory area or file mapping,
+other processes may currently have additional pages mapped in a
+corresponding memory range.
+.TP
+.I file=<filename>
+The file backing the memory range.
+If the file is mapped as private, write accesses may have generated
+COW (Copy-On-Write) pages in this memory range.
+These pages are displayed as anonymous pages.
+.TP
+.I heap
+Memory range is used for the heap.
+.TP
+.I stack
+Memory range is used for the stack.
+.TP
+.I huge
+Huge memory range.
+The page counts shown are huge pages and not regular sized pages.
+.TP
+.I anon=<pages>
+The number of anonymous page in the range.
+.TP
+.I dirty=<pages>
+Number of dirty pages.
+.TP
+.I mapped=<pages>
+Total number of mapped pages, if different from
+.I dirty
+and
+.I anon
+pages.
+.TP
+.I mapmax=<count>
+Maximum mapcount (number of processes mapping a single page) encountered
+during the scan.
+This may be used as an indicator of the degree of sharing occurring in a
+given memory range.
+.TP
+.I swapcache=<count>
+Number of pages that have an associated entry on a swap device.
+.TP
+.I active=<pages>
+The number of pages on the active list.
+This field is shown only if different from the number of pages in this range.
+This means that some inactive pages exist in the memory range that may be
+removed from memory by the swapper soon.
+.TP
+.I writeback=<pages>
+Number of pages that are currently being written out to disk.
+.SH STANDARDS
+None.
+.SH NOTES
+The Linux NUMA system calls and
+.I /proc
+interface are available only
+if the kernel was configured and built with the
+.B CONFIG_NUMA
+option.
+.SS Library support
+Link with \fI\-lnuma\fP
+to get the system call definitions.
+.I libnuma
+and the required
+.I <numaif.h>
+header are available in the
+.I numactl
+package.
+.P
+However, applications should not use these system calls directly.
+Instead, the higher level interface provided by the
+.BR numa (3)
+functions in the
+.I numactl
+package is recommended.
+The
+.I numactl
+package is available at
+.UR ftp://oss.sgi.com\:/www\:/projects\:/libnuma\:/download/
+.UE .
+The package is also included in some Linux distributions.
+Some distributions include the development library and header
+in the separate
+.I numactl\-devel
+package.
+.SH SEE ALSO
+.BR get_mempolicy (2),
+.BR mbind (2),
+.BR move_pages (2),
+.BR set_mempolicy (2),
+.BR numa (3),
+.BR cpuset (7),
+.BR numactl (8)
diff --git a/man/man7/operator.7 b/man/man7/operator.7
new file mode 100644
index 000000000..afa5485df
--- /dev/null
+++ b/man/man7/operator.7
@@ -0,0 +1,54 @@
+'\" t
+.\" Copyright (c) 1989, 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"	@(#)operator.7	8.1 (Berkeley) 6/9/93
+.\"
+.\" Copied shamelessly from FreeBSD with minor changes. 2003-05-21
+.\"     Brian M. Carlson <sandals@crustytoothpaste.ath.cx>
+.\"
+.\" Restored automatic formatting from FreeBSD.  2003-08-24
+.\"	Martin Schulze <joey@infodrom.org>
+.\"
+.\" 2007-12-08, mtk, Converted from mdoc to man macros
+.\"
+.TH operator 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+operator \- C operator precedence and order of evaluation
+.SH DESCRIPTION
+This manual page lists C operators and their precedence in evaluation.
+.P
+.TS
+lb lb lb
+l l l.
+Operator	Associativity	Notes
+[] () . \-> ++ \-\-	left to right	[1]
+++ \-\- & * + \- \[ti] ! sizeof	right to left	[2]
+(type)	right to left
+* / %	left to right
++ \-	left to right
+<< >>	left to right
+< > <= >=	left to right
+== !=	left to right
+&	left to right
+\[ha]	left to right
+|	left to right
+&&	left to right
+||	left to right
+?:	right to left
+= *= /= %= += \-= <<= >>= &= \[ha]= |=	right to left
+,	left to right
+.TE
+.P
+The following notes provide further information to the above table:
+.P
+.PD 0
+.IP [1] 5
+The ++ and \-\- operators at this precedence level are
+the postfix flavors of the operators.
+.IP [2]
+The ++ and \-\- operators at this precedence level are
+the prefix flavors of the operators.
+.PD
diff --git a/man/man7/packet.7 b/man/man7/packet.7
new file mode 100644
index 000000000..513945eff
--- /dev/null
+++ b/man/man7/packet.7
@@ -0,0 +1,694 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: packet.7,v 1.13 2000/08/14 08:03:45 ak Exp $
+.\"
+.TH packet 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+packet \- packet interface on device level
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <linux/if_packet.h>
+.B #include <net/ethernet.h>     /* the L2 protocols */
+.P
+.BI "packet_socket = socket(AF_PACKET, int " socket_type ", int "protocol );
+.fi
+.SH DESCRIPTION
+Packet sockets are used to receive or send raw packets at the device driver
+(OSI Layer 2) level.
+They allow the user to implement protocol modules in user space
+on top of the physical layer.
+.P
+The
+.I socket_type
+is either
+.B SOCK_RAW
+for raw packets including the link-level header or
+.B SOCK_DGRAM
+for cooked packets with the link-level header removed.
+The link-level header information is available in a common format in a
+.I sockaddr_ll
+structure.
+.I protocol
+is the IEEE 802.3 protocol number in network byte order.
+See the
+.I <linux/if_ether.h>
+include file for a list of allowed protocols.
+When protocol
+is set to
+.BR htons(ETH_P_ALL) ,
+then all protocols are received.
+All incoming packets of that protocol type will be passed to the packet
+socket before they are passed to the protocols implemented in the kernel.
+If
+.I protocol
+is set to zero,
+no packets are received.
+.BR bind (2)
+can optionally be called with a nonzero
+.I sll_protocol
+to start receiving packets for the protocols specified.
+.P
+In order to create a packet socket, a process must have the
+.B CAP_NET_RAW
+capability in the user namespace that governs its network namespace.
+.P
+.B SOCK_RAW
+packets are passed to and from the device driver without any changes in
+the packet data.
+When receiving a packet, the address is still parsed and
+passed in a standard
+.I sockaddr_ll
+address structure.
+When transmitting a packet, the user-supplied buffer
+should contain the physical-layer header.
+That packet is then
+queued unmodified to the network driver of the interface defined by the
+destination address.
+Some device drivers always add other headers.
+.B SOCK_RAW
+is similar to but not compatible with the obsolete
+.B AF_INET/SOCK_PACKET
+of Linux 2.0.
+.P
+.B SOCK_DGRAM
+operates on a slightly higher level.
+The physical header is removed before the packet is passed to the user.
+Packets sent through a
+.B SOCK_DGRAM
+packet socket get a suitable physical-layer header based on the
+information in the
+.I sockaddr_ll
+destination address before they are queued.
+.P
+By default, all packets of the specified protocol type
+are passed to a packet socket.
+To get packets only from a specific interface use
+.BR bind (2)
+specifying an address in a
+.I struct sockaddr_ll
+to bind the packet socket to an interface.
+Fields used for binding are
+.I sll_family
+(should be
+.BR AF_PACKET ),
+.IR sll_protocol ,
+and
+.IR sll_ifindex .
+.P
+The
+.BR connect (2)
+operation is not supported on packet sockets.
+.P
+When the
+.B MSG_TRUNC
+flag is passed to
+.BR recvmsg (2),
+.BR recv (2),
+or
+.BR recvfrom (2),
+the real length of the packet on the wire is always returned,
+even when it is longer than the buffer.
+.SS Address types
+The
+.I sockaddr_ll
+structure is a device-independent physical-layer address.
+.P
+.in +4n
+.EX
+struct sockaddr_ll {
+    unsigned short sll_family;   /* Always AF_PACKET */
+    unsigned short sll_protocol; /* Physical\-layer protocol */
+    int            sll_ifindex;  /* Interface number */
+    unsigned short sll_hatype;   /* ARP hardware type */
+    unsigned char  sll_pkttype;  /* Packet type */
+    unsigned char  sll_halen;    /* Length of address */
+    unsigned char  sll_addr[8];  /* Physical\-layer address */
+};
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I sll_protocol
+is the standard ethernet protocol type in network byte order as defined
+in the
+.I <linux/if_ether.h>
+include file.
+It defaults to the socket's protocol.
+.TP
+.I sll_ifindex
+is the interface index of the interface
+(see
+.BR netdevice (7));
+0 matches any interface (only permitted for binding).
+.I sll_hatype
+is an ARP type as defined in the
+.I <linux/if_arp.h>
+include file.
+.TP
+.I sll_pkttype
+contains the packet type.
+Valid types are
+.B PACKET_HOST
+for a packet addressed to the local host,
+.B PACKET_BROADCAST
+for a physical-layer broadcast packet,
+.B PACKET_MULTICAST
+for a packet sent to a physical-layer multicast address,
+.B PACKET_OTHERHOST
+for a packet to some other host that has been caught by a device driver
+in promiscuous mode, and
+.B PACKET_OUTGOING
+for a packet originating from the local host that is looped back to a packet
+socket.
+These types make sense only for receiving.
+.TP
+.I sll_addr
+.TQ
+.I sll_halen
+contain the physical-layer (e.g., IEEE 802.3) address and its length.
+The exact interpretation depends on the device.
+.P
+When you send packets, it is enough to specify
+.IR sll_family ,
+.IR sll_addr ,
+.IR sll_halen ,
+.IR sll_ifindex ,
+and
+.IR sll_protocol .
+The other fields should be 0.
+.I sll_hatype
+and
+.I sll_pkttype
+are set on received packets for your information.
+.SS Socket options
+Packet socket options are configured by calling
+.BR setsockopt (2)
+with level
+.BR SOL_PACKET .
+.TP
+.B PACKET_ADD_MEMBERSHIP
+.PD 0
+.TP
+.B PACKET_DROP_MEMBERSHIP
+.PD
+Packet sockets can be used to configure physical-layer multicasting
+and promiscuous mode.
+.B PACKET_ADD_MEMBERSHIP
+adds a binding and
+.B PACKET_DROP_MEMBERSHIP
+drops it.
+They both expect a
+.I packet_mreq
+structure as argument:
+.IP
+.in +4n
+.EX
+struct packet_mreq {
+    int            mr_ifindex;    /* interface index */
+    unsigned short mr_type;       /* action */
+    unsigned short mr_alen;       /* address length */
+    unsigned char  mr_address[8]; /* physical\-layer address */
+};
+.EE
+.in
+.IP
+.I mr_ifindex
+contains the interface index for the interface whose status
+should be changed.
+The
+.I mr_type
+field specifies which action to perform.
+.B PACKET_MR_PROMISC
+enables receiving all packets on a shared medium (often known as
+"promiscuous mode"),
+.B PACKET_MR_MULTICAST
+binds the socket to the physical-layer multicast group specified in
+.I mr_address
+and
+.IR mr_alen ,
+and
+.B PACKET_MR_ALLMULTI
+sets the socket up to receive all multicast packets arriving at
+the interface.
+.IP
+In addition, the traditional ioctls
+.BR SIOCSIFFLAGS ,
+.BR SIOCADDMULTI ,
+.B SIOCDELMULTI
+can be used for the same purpose.
+.TP
+.BR PACKET_AUXDATA " (since Linux 2.6.21)"
+.\" commit 8dc4194474159660d7f37c495e3fc3f10d0db8cc
+If this binary option is enabled, the packet socket passes a metadata
+structure along with each packet in the
+.BR recvmsg (2)
+control field.
+The structure can be read with
+.BR cmsg (3).
+It is defined as
+.IP
+.in +4n
+.EX
+struct tpacket_auxdata {
+    __u32 tp_status;
+    __u32 tp_len;      /* packet length */
+    __u32 tp_snaplen;  /* captured length */
+    __u16 tp_mac;
+    __u16 tp_net;
+    __u16 tp_vlan_tci;
+    __u16 tp_vlan_tpid; /* Since Linux 3.14; earlier, these
+                           were unused padding bytes */
+.\" commit a0cdfcf39362410d5ea983f4daf67b38de129408 added tp_vlan_tpid
+};
+.EE
+.in
+.TP
+.BR PACKET_FANOUT " (since Linux 3.1)"
+.\" commit dc99f600698dcac69b8f56dda9a8a00d645c5ffc
+To scale processing across threads, packet sockets can form a fanout
+group.
+In this mode, each matching packet is enqueued onto only one
+socket in the group.
+A socket joins a fanout group by calling
+.BR setsockopt (2)
+with level
+.B SOL_PACKET
+and option
+.BR PACKET_FANOUT .
+Each network namespace can have up to 65536 independent groups.
+A socket selects a group by encoding the ID in the first 16 bits of
+the integer option value.
+The first packet socket to join a group implicitly creates it.
+To successfully join an existing group, subsequent packet sockets
+must have the same protocol, device settings, fanout mode, and
+flags (see below).
+Packet sockets can leave a fanout group only by closing the socket.
+The group is deleted when the last socket is closed.
+.IP
+Fanout supports multiple algorithms to spread traffic between sockets,
+as follows:
+.RS
+.IP \[bu] 3
+The default mode,
+.BR PACKET_FANOUT_HASH ,
+sends packets from the same flow to the same socket to maintain
+per-flow ordering.
+For each packet, it chooses a socket by taking the packet flow hash
+modulo the number of sockets in the group, where a flow hash is a hash
+over network-layer address and optional transport-layer port fields.
+.IP \[bu]
+The load-balance mode
+.B PACKET_FANOUT_LB
+implements a round-robin algorithm.
+.IP \[bu]
+.B PACKET_FANOUT_CPU
+selects the socket based on the CPU that the packet arrived on.
+.IP \[bu]
+.B PACKET_FANOUT_ROLLOVER
+processes all data on a single socket, moving to the next when one
+becomes backlogged.
+.IP \[bu]
+.B PACKET_FANOUT_RND
+selects the socket using a pseudo-random number generator.
+.IP \[bu]
+.B PACKET_FANOUT_QM
+.\" commit 2d36097d26b5991d71a2cf4a20c1a158f0f1bfcd
+(available since Linux 3.14)
+selects the socket using the recorded queue_mapping of the received skb.
+.RE
+.IP
+Fanout modes can take additional options.
+IP fragmentation causes packets from the same flow to have different
+flow hashes.
+The flag
+.BR PACKET_FANOUT_FLAG_DEFRAG ,
+if set, causes packets to be defragmented before fanout is applied, to
+preserve order even in this case.
+Fanout mode and options are communicated in the second 16 bits of the
+integer option value.
+The flag
+.B PACKET_FANOUT_FLAG_ROLLOVER
+enables the roll over mechanism as a backup strategy: if the
+original fanout algorithm selects a backlogged socket, the packet
+rolls over to the next available one.
+.TP
+.BR PACKET_LOSS " (with " PACKET_TX_RING )
+When a malformed packet is encountered on a transmit ring,
+the default is to reset its
+.I tp_status
+to
+.B TP_STATUS_WRONG_FORMAT
+and abort the transmission immediately.
+The malformed packet blocks itself and subsequently enqueued packets from
+being sent.
+The format error must be fixed, the associated
+.I tp_status
+reset to
+.BR TP_STATUS_SEND_REQUEST ,
+and the transmission process restarted via
+.BR send (2).
+However, if
+.B PACKET_LOSS
+is set, any malformed packet will be skipped, its
+.I tp_status
+reset to
+.BR TP_STATUS_AVAILABLE ,
+and the transmission process continued.
+.TP
+.BR PACKET_RESERVE " (with " PACKET_RX_RING )
+By default, a packet receive ring writes packets immediately following the
+metadata structure and alignment padding.
+This integer option reserves additional headroom.
+.TP
+.B PACKET_RX_RING
+Create a memory-mapped ring buffer for asynchronous packet reception.
+The packet socket reserves a contiguous region of application address
+space, lays it out into an array of packet slots and copies packets
+(up to
+.IR tp_snaplen )
+into subsequent slots.
+Each packet is preceded by a metadata structure similar to
+.IR tpacket_auxdata .
+The protocol fields encode the offset to the data
+from the start of the metadata header.
+.I tp_net
+stores the offset to the network layer.
+If the packet socket is of type
+.BR SOCK_DGRAM ,
+then
+.I tp_mac
+is the same.
+If it is of type
+.BR SOCK_RAW ,
+then that field stores the offset to the link-layer frame.
+Packet socket and application communicate the head and tail of the ring
+through the
+.I tp_status
+field.
+The packet socket owns all slots with
+.I tp_status
+equal to
+.BR TP_STATUS_KERNEL .
+After filling a slot, it changes the status of the slot to transfer
+ownership to the application.
+During normal operation, the new
+.I tp_status
+value has at least the
+.B TP_STATUS_USER
+bit set to signal that a received packet has been stored.
+When the application has finished processing a packet, it transfers
+ownership of the slot back to the socket by setting
+.I tp_status
+equal to
+.BR TP_STATUS_KERNEL .
+.IP
+Packet sockets implement multiple variants of the packet ring.
+The implementation details are described in
+.I Documentation/networking/packet_mmap.rst
+in the Linux kernel source tree.
+.TP
+.B PACKET_STATISTICS
+Retrieve packet socket statistics in the form of a structure
+.IP
+.in +4n
+.EX
+struct tpacket_stats {
+    unsigned int tp_packets;  /* Total packet count */
+    unsigned int tp_drops;    /* Dropped packet count */
+};
+.EE
+.in
+.IP
+Receiving statistics resets the internal counters.
+The statistics structure differs when using a ring of variant
+.BR TPACKET_V3 .
+.TP
+.BR PACKET_TIMESTAMP " (with " PACKET_RX_RING "; since Linux 2.6.36)"
+.\" commit 614f60fa9d73a9e8fdff3df83381907fea7c5649
+The packet receive ring always stores a timestamp in the metadata header.
+By default, this is a software generated timestamp generated when the
+packet is copied into the ring.
+This integer option selects the type of timestamp.
+Besides the default, it support the two hardware formats described in
+.I Documentation/networking/timestamping.rst
+in the Linux kernel source tree.
+.TP
+.BR PACKET_TX_RING " (since Linux 2.6.31)"
+.\" commit 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1
+Create a memory-mapped ring buffer for packet transmission.
+This option is similar to
+.B PACKET_RX_RING
+and takes the same arguments.
+The application writes packets into slots with
+.I tp_status
+equal to
+.B TP_STATUS_AVAILABLE
+and schedules them for transmission by changing
+.I tp_status
+to
+.BR TP_STATUS_SEND_REQUEST .
+When packets are ready to be transmitted, the application calls
+.BR send (2)
+or a variant thereof.
+The
+.I buf
+and
+.I len
+fields of this call are ignored.
+If an address is passed using
+.BR sendto (2)
+or
+.BR sendmsg (2),
+then that overrides the socket default.
+On successful transmission, the socket resets
+.I tp_status
+to
+.BR TP_STATUS_AVAILABLE .
+It immediately aborts the transmission on error unless
+.B PACKET_LOSS
+is set.
+.TP
+.BR PACKET_VERSION " (with " PACKET_RX_RING "; since Linux 2.6.27)"
+.\" commit bbd6ef87c544d88c30e4b762b1b61ef267a7d279
+By default,
+.B PACKET_RX_RING
+creates a packet receive ring of variant
+.BR TPACKET_V1 .
+To create another variant, configure the desired variant by setting this
+integer option before creating the ring.
+.TP
+.BR PACKET_QDISC_BYPASS " (since Linux 3.14)"
+.\" commit d346a3fae3ff1d99f5d0c819bf86edf9094a26a1
+By default, packets sent through packet sockets pass through the kernel's
+qdisc (traffic control) layer, which is fine for the vast majority of use
+cases.
+For traffic generator appliances using packet sockets
+that intend to brute-force flood the network\[em]for example,
+to test devices under load in a similar
+fashion to pktgen\[em]this layer can be bypassed by setting
+this integer option to 1.
+A side effect is that packet buffering in the qdisc layer is avoided,
+which will lead to increased drops when network
+device transmit queues are busy;
+therefore, use at your own risk.
+.SS Ioctls
+.B SIOCGSTAMP
+can be used to receive the timestamp of the last received packet.
+Argument is a
+.I struct timeval
+variable.
+.\" FIXME Document SIOCGSTAMPNS
+.P
+In addition, all standard ioctls defined in
+.BR netdevice (7)
+and
+.BR socket (7)
+are valid on packet sockets.
+.SS Error handling
+Packet sockets do no error handling other than errors occurred
+while passing the packet to the device driver.
+They don't have the concept of a pending error.
+.SH ERRORS
+.TP
+.B EADDRNOTAVAIL
+Unknown multicast group address passed.
+.TP
+.B EFAULT
+User passed invalid memory address.
+.TP
+.B EINVAL
+Invalid argument.
+.TP
+.B EMSGSIZE
+Packet is bigger than interface MTU.
+.TP
+.B ENETDOWN
+Interface is not up.
+.TP
+.B ENOBUFS
+Not enough memory to allocate the packet.
+.TP
+.B ENODEV
+Unknown device name or interface index specified in interface address.
+.TP
+.B ENOENT
+No packet received.
+.TP
+.B ENOTCONN
+No interface address passed.
+.TP
+.B ENXIO
+Interface address contained an invalid interface index.
+.TP
+.B EPERM
+User has insufficient privileges to carry out this operation.
+.P
+In addition, other errors may be generated by the low-level driver.
+.SH VERSIONS
+.B AF_PACKET
+is a new feature in Linux 2.2.
+Earlier Linux versions supported only
+.BR SOCK_PACKET .
+.SH NOTES
+For portable programs it is suggested to use
+.B AF_PACKET
+via
+.BR pcap (3);
+although this covers only a subset of the
+.B AF_PACKET
+features.
+.P
+The
+.B SOCK_DGRAM
+packet sockets make no attempt to create or parse the IEEE 802.2 LLC
+header for a IEEE 802.3 frame.
+When
+.B ETH_P_802_3
+is specified as protocol for sending the kernel creates the
+802.3 frame and fills out the length field; the user has to supply the LLC
+header to get a fully conforming packet.
+Incoming 802.3 packets are not multiplexed on the DSAP/SSAP protocol
+fields; instead they are supplied to the user as protocol
+.B ETH_P_802_2
+with the LLC header prefixed.
+It is thus not possible to bind to
+.BR ETH_P_802_3 ;
+bind to
+.B ETH_P_802_2
+instead and do the protocol multiplex yourself.
+The default for sending is the standard Ethernet DIX
+encapsulation with the protocol filled in.
+.P
+Packet sockets are not subject to the input or output firewall chains.
+.SS Compatibility
+In Linux 2.0, the only way to get a packet socket was with the call:
+.P
+.in +4n
+.EX
+socket(AF_INET, SOCK_PACKET, protocol)
+.EE
+.in
+.P
+This is still supported, but deprecated and strongly discouraged.
+The main difference between the two methods is that
+.B SOCK_PACKET
+uses the old
+.I struct sockaddr_pkt
+to specify an interface, which doesn't provide physical-layer
+independence.
+.P
+.in +4n
+.EX
+struct sockaddr_pkt {
+    unsigned short spkt_family;
+    unsigned char  spkt_device[14];
+    unsigned short spkt_protocol;
+};
+.EE
+.in
+.P
+.I spkt_family
+contains
+the device type,
+.I spkt_protocol
+is the IEEE 802.3 protocol type as defined in
+.I <sys/if_ether.h>
+and
+.I spkt_device
+is the device name as a null-terminated string, for example, eth0.
+.P
+This structure is obsolete and should not be used in new code.
+.SH BUGS
+.SS LLC header handling
+The IEEE 802.2/803.3 LLC handling could be considered as a bug.
+.SS MSG_TRUNC issues
+The
+.B MSG_TRUNC
+.BR recvmsg (2)
+extension is an ugly hack and should be replaced by a control message.
+There is currently no way to get the original destination address of
+packets via
+.BR SOCK_DGRAM .
+.SS spkt_device device name truncation
+The
+.I spkt_device
+field of
+.I sockaddr_pkt
+has a size of 14 bytes,
+which is less than the constant
+.B IFNAMSIZ
+defined in
+.I <net/if.h>
+which is 16 bytes and describes the system limit for a network interface name.
+This means the names of network devices longer than 14 bytes
+will be truncated to fit into
+.IR spkt_device .
+All these lengths include the terminating null byte (\[aq]\e0\[aq])).
+.P
+Issues from this with old code typically show up with
+very long interface names used by the
+.B Predictable Network Interface Names
+feature enabled by default in many modern Linux distributions.
+.P
+The preferred solution is to rewrite code to avoid
+.BR SOCK_PACKET .
+Possible user solutions are to disable
+.B Predictable Network Interface Names
+or to rename the interface to a name of at most 13 bytes,
+for example using the
+.BR ip (8)
+tool.
+.SS Documentation issues
+Socket filters are not documented.
+.\" .SH CREDITS
+.\" This man page was written by Andi Kleen with help from Matthew Wilcox.
+.\" AF_PACKET in Linux 2.2 was implemented
+.\" by Alexey Kuznetsov, based on code by Alan Cox and others.
+.SH SEE ALSO
+.BR socket (2),
+.BR pcap (3),
+.BR capabilities (7),
+.BR ip (7),
+.BR raw (7),
+.BR socket (7),
+.BR ip (8),
+.P
+RFC\ 894 for the standard IP Ethernet encapsulation.
+RFC\ 1700 for the IEEE 802.3 IP encapsulation.
+.P
+The
+.I <linux/if_ether.h>
+include file for physical-layer protocols.
+.P
+The Linux kernel source tree.
+.I Documentation/networking/filter.rst
+describes how to apply Berkeley Packet Filters to packet sockets.
+.I tools/testing/selftests/net/psock_tpacket.c
+contains example source code for all available versions of
+.B PACKET_RX_RING
+and
+.BR PACKET_TX_RING .
diff --git a/man/man7/path_resolution.7 b/man/man7/path_resolution.7
new file mode 100644
index 000000000..8cb369a0d
--- /dev/null
+++ b/man/man7/path_resolution.7
@@ -0,0 +1,264 @@
+.\" Copyright (C) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH path_resolution 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+path_resolution \- how a pathname is resolved to a file
+.SH DESCRIPTION
+Some UNIX/Linux system calls have as parameter one or more filenames.
+A filename (or pathname) is resolved as follows.
+.SS Step 1: start of the resolution process
+If the pathname starts with the \[aq]/\[aq] character, the starting lookup
+directory is the root directory of the calling process.
+A process inherits its root directory from its parent.
+Usually this will be the root directory of the file hierarchy.
+A process may get a different root directory by use of the
+.BR chroot (2)
+system call, or may temporarily use a different root directory by using
+.BR openat2 (2)
+with the
+.B RESOLVE_IN_ROOT
+flag set.
+.P
+A process may get an entirely private mount namespace in case
+it\[em]or one of its ancestors\[em]was started by an invocation of the
+.BR clone (2)
+system call that had the
+.B CLONE_NEWNS
+flag set.
+This handles the \[aq]/\[aq] part of the pathname.
+.P
+If the pathname does not start with the \[aq]/\[aq] character, the starting
+lookup directory of the resolution process is the current working directory of
+the process \[em] or in the case of
+.BR openat (2)-style
+system calls, the
+.I dfd
+argument (or the current working directory if
+.B AT_FDCWD
+is passed as the
+.I dfd
+argument).
+The current working directory is inherited from the parent, and can
+be changed by use of the
+.BR chdir (2)
+system call.
+.P
+Pathnames starting with a \[aq]/\[aq] character are called absolute pathnames.
+Pathnames not starting with a \[aq]/\[aq] are called relative pathnames.
+.SS Step 2: walk along the path
+Set the current lookup directory to the starting lookup directory.
+Now, for each nonfinal component of the pathname, where a component
+is a substring delimited by \[aq]/\[aq] characters, this component is looked up
+in the current lookup directory.
+.P
+If the process does not have search permission on
+the current lookup directory,
+an
+.B EACCES
+error is returned ("Permission denied").
+.P
+If the component is not found, an
+.B ENOENT
+error is returned
+("No such file or directory").
+.P
+If the component is found, but is neither a directory nor a symbolic link,
+an
+.B ENOTDIR
+error is returned ("Not a directory").
+.P
+If the component is found and is a directory, we set the
+current lookup directory to that directory, and go to the
+next component.
+.P
+If the component is found and is a symbolic link,
+we first resolve this symbolic link
+(with the current lookup directory
+as starting lookup directory).
+Upon error, that error is returned.
+If the result is not a directory, an
+.B ENOTDIR
+error is returned.
+If the resolution of the symbolic link is successful and returns a directory,
+we set the current lookup directory to that directory, and go to
+the next component.
+Note that the resolution process here can involve recursion if the
+prefix ('dirname') component of a pathname contains a filename
+that is a symbolic link that resolves to a directory (where the
+prefix component of that directory may contain a symbolic link, and so on).
+In order to protect the kernel against stack overflow, and also
+to protect against denial of service, there are limits on the
+maximum recursion depth, and on the maximum number of symbolic links
+followed.
+An
+.B ELOOP
+error is returned when the maximum is
+exceeded ("Too many levels of symbolic links").
+.P
+.\"
+.\" presently: max recursion depth during symlink resolution: 5
+.\" max total number of symbolic links followed: 40
+.\" _POSIX_SYMLOOP_MAX is 8
+As currently implemented on Linux, the maximum number
+.\" MAXSYMLINKS is 40
+of symbolic links that will be followed while resolving a pathname is 40.
+Before Linux 2.6.18, the limit on the recursion depth was 5.
+Starting with Linux 2.6.18, this limit
+.\" MAX_NESTED_LINKS
+was raised to 8.
+In Linux 4.2,
+.\" commit 894bc8c4662ba9daceafe943a5ba0dd407da5cd3
+the kernel's pathname-resolution code
+was reworked to eliminate the use of recursion,
+so that the only limit that remains is the maximum of 40
+resolutions for the entire pathname.
+.P
+The resolution of symbolic links during this stage can be blocked by using
+.BR openat2 (2),
+with the
+.B RESOLVE_NO_SYMLINKS
+flag set.
+.SS Step 3: find the final entry
+The lookup of the final component of the pathname goes just like
+that of all other components, as described in the previous step,
+with two differences: (i) the final component need not be a
+directory (at least as far as the path resolution process is
+concerned\[em]it may have to be a directory, or a nondirectory, because of
+the requirements of the specific system call), and (ii) it
+is not necessarily an error if the component is not found\[em]maybe
+we are just creating it.
+The details on the treatment
+of the final entry are described in the manual pages of the specific
+system calls.
+.SS "\&. and .."
+By convention, every directory has the entries "." and "..",
+which refer to the directory itself and to its parent directory,
+respectively.
+.P
+The path resolution process will assume that these entries have
+their conventional meanings, regardless of whether they are
+actually present in the physical filesystem.
+.P
+One cannot walk up past the root: "/.." is the same as "/".
+.SS Mount points
+After a
+.I mount dev path
+command, the pathname "path" refers to
+the root of the filesystem hierarchy on the device "dev", and no
+longer to whatever it referred to earlier.
+.P
+One can walk out of a mounted filesystem: "path/.." refers to
+the parent directory of "path",
+outside of the filesystem hierarchy on "dev".
+.P
+Traversal of mount points can be blocked by using
+.BR openat2 (2),
+with the
+.B RESOLVE_NO_XDEV
+flag set (though note that this also restricts bind mount traversal).
+.SS Trailing slashes
+If a pathname ends in a \[aq]/\[aq], that forces resolution of the preceding
+component as in Step 2:
+the component preceding the slash either exists and resolves to a directory
+or it names a directory that is to be created
+immediately after the pathname is resolved.
+Otherwise, a trailing \[aq]/\[aq] is ignored.
+.SS Final symbolic link
+If the last component of a pathname is a symbolic link, then it
+depends on the system call whether the file referred to will be
+the symbolic link or the result of path resolution on its contents.
+For example, the system call
+.BR lstat (2)
+will operate on the symbolic link,
+while
+.BR stat (2)
+operates on the file pointed to by the symbolic link.
+.SS Length limit
+There is a maximum length for pathnames.
+If the pathname (or some
+intermediate pathname obtained while resolving symbolic links)
+is too long, an
+.B ENAMETOOLONG
+error is returned ("Filename too long").
+.SS Empty pathname
+In the original UNIX, the empty pathname referred to the current directory.
+Nowadays POSIX decrees that an empty pathname must not be resolved
+successfully.
+Linux returns
+.B ENOENT
+in this case.
+.SS Permissions
+The permission bits of a file consist of three groups of three bits; see
+.BR chmod (1)
+and
+.BR stat (2).
+The first group of three is used when the effective user ID of
+the calling process equals the owner ID of the file.
+The second group
+of three is used when the group ID of the file either equals the
+effective group ID of the calling process, or is one of the
+supplementary group IDs of the calling process (as set by
+.BR setgroups (2)).
+When neither holds, the third group is used.
+.P
+Of the three bits used, the first bit determines read permission,
+the second write permission, and the last execute permission
+in case of ordinary files, or search permission in case of directories.
+.P
+Linux uses the fsuid instead of the effective user ID in permission checks.
+Ordinarily the fsuid will equal the effective user ID, but the fsuid can be
+changed by the system call
+.BR setfsuid (2).
+.P
+(Here "fsuid" stands for something like "filesystem user ID".
+The concept was required for the implementation of a user space
+NFS server at a time when processes could send a signal to a process
+with the same effective user ID.
+It is obsolete now.
+Nobody should use
+.BR setfsuid (2).)
+.P
+Similarly, Linux uses the fsgid ("filesystem group ID")
+instead of the effective group ID.
+See
+.BR setfsgid (2).
+.\" FIXME . say something about filesystem mounted read-only ?
+.SS Bypassing permission checks: superuser and capabilities
+On a traditional UNIX system, the superuser
+.RI ( root ,
+user ID 0) is all-powerful, and bypasses all permissions restrictions
+when accessing files.
+.\" (but for exec at least one x bit must be set) -- AEB
+.\" but there is variation across systems on this point: for
+.\" example, HP-UX and Tru64 are as described by AEB.  However,
+.\" on some implementations (e.g., Solaris, FreeBSD),
+.\" access(X_OK) by superuser will report success, regardless
+.\" of the file's execute permission bits. -- MTK (Oct 05)
+.P
+On Linux, superuser privileges are divided into capabilities (see
+.BR capabilities (7)).
+Two capabilities are relevant for file permissions checks:
+.B CAP_DAC_OVERRIDE
+and
+.BR CAP_DAC_READ_SEARCH .
+(A process has these capabilities if its fsuid is 0.)
+.P
+The
+.B CAP_DAC_OVERRIDE
+capability overrides all permission checking,
+but grants execute permission only when at least one
+of the file's three execute permission bits is set.
+.P
+The
+.B CAP_DAC_READ_SEARCH
+capability grants read and search permission
+on directories, and read permission on ordinary files.
+.\" FIXME . say something about immutable files
+.\" FIXME . say something about ACLs
+.SH SEE ALSO
+.BR readlink (2),
+.BR capabilities (7),
+.BR credentials (7),
+.BR symlink (7)
diff --git a/man/man7/persistent-keyring.7 b/man/man7/persistent-keyring.7
new file mode 100644
index 000000000..90b5a168d
--- /dev/null
+++ b/man/man7/persistent-keyring.7
@@ -0,0 +1,124 @@
+.\" Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH persistent-keyring 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+persistent-keyring \- per-user persistent keyring
+.SH DESCRIPTION
+The persistent keyring is a keyring used to anchor keys on behalf of a user.
+Each UID the kernel deals with has its own persistent keyring that
+is shared between all threads owned by that UID.
+The persistent keyring has a name (description) of the form
+.I _persistent.<UID>
+where
+.I <UID>
+is the user ID of the corresponding user.
+.P
+The persistent keyring may not be accessed directly,
+even by processes with the appropriate UID.
+.\" FIXME The meaning of the preceding sentence isn't clear. What is meant?
+Instead, it must first be linked to one of a process's keyrings,
+before that keyring can access the persistent keyring
+by virtue of its possessor permits.
+This linking is done with the
+.BR keyctl_get_persistent (3)
+function.
+.P
+If a persistent keyring does not exist when it is accessed by the
+.BR keyctl_get_persistent (3)
+operation, it will be automatically created.
+.P
+Each time the
+.BR keyctl_get_persistent (3)
+operation is performed,
+the persistent keyring's expiration timer is reset to the value in:
+.P
+.in +4n
+.EX
+/proc/sys/kernel/keys/persistent_keyring_expiry
+.EE
+.in
+.P
+Should the timeout be reached,
+the persistent keyring will be removed and
+everything it pins can then be garbage collected.
+The keyring will then be re-created on a subsequent call to
+.BR keyctl_get_persistent (3).
+.P
+The persistent keyring is not directly searched by
+.BR request_key (2);
+it is searched only if it is linked into one of the keyrings
+that is searched by
+.BR request_key (2).
+.P
+The persistent keyring is independent of
+.BR clone (2),
+.BR fork (2),
+.BR vfork (2),
+.BR execve (2),
+and
+.BR _exit (2).
+It persists until its expiration timer triggers,
+at which point it is garbage collected.
+This allows the persistent keyring to carry keys beyond the life of
+the kernel's record of the corresponding UID
+(the destruction of which results in the destruction of the
+.BR user\-keyring (7)
+and the
+.BR user\-session\-keyring (7)).
+The persistent keyring can thus be used to
+hold authentication tokens for processes that run without user interaction,
+such as programs started by
+.BR cron (8).
+.P
+The persistent keyring is used to store UID-specific objects that
+themselves have limited lifetimes (e.g., kerberos tokens).
+If those tokens cease to be used
+(i.e., the persistent keyring is not accessed),
+then the timeout of the persistent keyring ensures that
+the corresponding objects are automatically discarded.
+.\"
+.SS Special operations
+The
+.I keyutils
+library provides the
+.BR keyctl_get_persistent (3)
+function for manipulating persistent keyrings.
+(This function is an interface to the
+.BR keyctl (2)
+.B KEYCTL_GET_PERSISTENT
+operation.)
+This operation allows the calling thread to get the persistent keyring
+corresponding to its own UID or, if the thread has the
+.B CAP_SETUID
+capability, the persistent keyring corresponding to some other UID
+in the same user namespace.
+.SH NOTES
+Each user namespace owns a keyring called
+.I .persistent_register
+that contains links to all of the persistent keys in that namespace.
+(The
+.I .persistent_register
+keyring can be seen when reading the contents of the
+.I /proc/keys
+file for the UID 0 in the namespace.)
+The
+.BR keyctl_get_persistent (3)
+operation looks for a key with a name of the form
+.IR _persistent. UID
+in that keyring,
+creates the key if it does not exist, and links it into the keyring.
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR keyctl (3),
+.BR keyctl_get_persistent (3),
+.BR keyrings (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7),
+.BR user\-session\-keyring (7)
diff --git a/man/man7/pid_namespaces.7 b/man/man7/pid_namespaces.7
new file mode 100644
index 000000000..c886a034d
--- /dev/null
+++ b/man/man7/pid_namespaces.7
@@ -0,0 +1,388 @@
+.\" Copyright (c) 2013 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (c) 2012 by Eric W. Biederman <ebiederm@xmission.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH pid_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pid_namespaces \- overview of Linux PID namespaces
+.SH DESCRIPTION
+For an overview of namespaces, see
+.BR namespaces (7).
+.P
+PID namespaces isolate the process ID number space,
+meaning that processes in different PID namespaces can have the same PID.
+PID namespaces allow containers to provide functionality
+such as suspending/resuming the set of processes in the container and
+migrating the container to a new host
+while the processes inside the container maintain the same PIDs.
+.P
+PIDs in a new PID namespace start at 1,
+somewhat like a standalone system, and calls to
+.BR fork (2),
+.BR vfork (2),
+or
+.BR clone (2)
+will produce processes with PIDs that are unique within the namespace.
+.P
+Use of PID namespaces requires a kernel that is configured with the
+.B CONFIG_PID_NS
+option.
+.\"
+.\" ============================================================
+.\"
+.SS The namespace "init" process
+The first process created in a new namespace
+(i.e., the process created using
+.BR clone (2)
+with the
+.B CLONE_NEWPID
+flag, or the first child created by a process after a call to
+.BR unshare (2)
+using the
+.B CLONE_NEWPID
+flag) has the PID 1, and is the "init" process for the namespace (see
+.BR init (1)).
+This process becomes the parent of any child processes that are orphaned
+because a process that resides in this PID namespace terminated
+(see below for further details).
+.P
+If the "init" process of a PID namespace terminates,
+the kernel terminates all of the processes in the namespace via a
+.B SIGKILL
+signal.
+This behavior reflects the fact that the "init" process
+is essential for the correct operation of a PID namespace.
+In this case, a subsequent
+.BR fork (2)
+into this PID namespace fail with the error
+.BR ENOMEM ;
+it is not possible to create a new process in a PID namespace whose "init"
+process has terminated.
+Such scenarios can occur when, for example,
+a process uses an open file descriptor for a
+.IR /proc/ pid /ns/pid
+file corresponding to a process that was in a namespace to
+.BR setns (2)
+into that namespace after the "init" process has terminated.
+Another possible scenario can occur after a call to
+.BR unshare (2):
+if the first child subsequently created by a
+.BR fork (2)
+terminates, then subsequent calls to
+.BR fork (2)
+fail with
+.BR ENOMEM .
+.P
+Only signals for which the "init" process has established a signal handler
+can be sent to the "init" process by other members of the PID namespace.
+This restriction applies even to privileged processes,
+and prevents other members of the PID namespace from
+accidentally killing the "init" process.
+.P
+Likewise, a process in an ancestor namespace
+can\[em]subject to the usual permission checks described in
+.BR kill (2)\[em]send
+signals to the "init" process of a child PID namespace only
+if the "init" process has established a handler for that signal.
+(Within the handler, the
+.I siginfo_t
+.I si_pid
+field described in
+.BR sigaction (2)
+will be zero.)
+.B SIGKILL
+or
+.B SIGSTOP
+are treated exceptionally:
+these signals are forcibly delivered when sent from an ancestor PID namespace.
+Neither of these signals can be caught by the "init" process,
+and so will result in the usual actions associated with those signals
+(respectively, terminating and stopping the process).
+.P
+Starting with Linux 3.4, the
+.BR reboot (2)
+system call causes a signal to be sent to the namespace "init" process.
+See
+.BR reboot (2)
+for more details.
+.\"
+.\" ============================================================
+.\"
+.SS Nesting PID namespaces
+PID namespaces can be nested:
+each PID namespace has a parent,
+except for the initial ("root") PID namespace.
+The parent of a PID namespace is the PID namespace of the process that
+created the namespace using
+.BR clone (2)
+or
+.BR unshare (2).
+PID namespaces thus form a tree,
+with all namespaces ultimately tracing their ancestry to the root namespace.
+Since Linux 3.7,
+.\" commit f2302505775fd13ba93f034206f1e2a587017929
+.\" The kernel constant MAX_PID_NS_LEVEL
+the kernel limits the maximum nesting depth for PID namespaces to 32.
+.P
+A process is visible to other processes in its PID namespace,
+and to the processes in each direct ancestor PID namespace
+going back to the root PID namespace.
+In this context, "visible" means that one process
+can be the target of operations by another process using
+system calls that specify a process ID.
+Conversely, the processes in a child PID namespace can't see
+processes in the parent and further removed ancestor namespaces.
+More succinctly: a process can see (e.g., send signals with
+.BR kill (2),
+set nice values with
+.BR setpriority (2),
+etc.) only processes contained in its own PID namespace
+and in descendants of that namespace.
+.P
+A process has one process ID in each of the layers of the PID
+namespace hierarchy in which is visible,
+and walking back though each direct ancestor namespace
+through to the root PID namespace.
+System calls that operate on process IDs always
+operate using the process ID that is visible in the
+PID namespace of the caller.
+A call to
+.BR getpid (2)
+always returns the PID associated with the namespace in which
+the process was created.
+.P
+Some processes in a PID namespace may have parents
+that are outside of the namespace.
+For example, the parent of the initial process in the namespace
+(i.e., the
+.BR init (1)
+process with PID 1) is necessarily in another namespace.
+Likewise, the direct children of a process that uses
+.BR setns (2)
+to cause its children to join a PID namespace are in a different
+PID namespace from the caller of
+.BR setns (2).
+Calls to
+.BR getppid (2)
+for such processes return 0.
+.P
+While processes may freely descend into child PID namespaces
+(e.g., using
+.BR setns (2)
+with a PID namespace file descriptor),
+they may not move in the other direction.
+That is to say, processes may not enter any ancestor namespaces
+(parent, grandparent, etc.).
+Changing PID namespaces is a one-way operation.
+.P
+The
+.B NS_GET_PARENT
+.BR ioctl (2)
+operation can be used to discover the parental relationship
+between PID namespaces; see
+.BR ioctl_ns (2).
+.\"
+.\" ============================================================
+.\"
+.SS setns(2) and unshare(2) semantics
+Calls to
+.BR setns (2)
+that specify a PID namespace file descriptor
+and calls to
+.BR unshare (2)
+with the
+.B CLONE_NEWPID
+flag cause children subsequently created
+by the caller to be placed in a different PID namespace from the caller.
+(Since Linux 4.12, that PID namespace is shown via the
+.IR /proc/ pid /ns/pid_for_children
+file, as described in
+.BR namespaces (7).)
+These calls do not, however,
+change the PID namespace of the calling process,
+because doing so would change the caller's idea of its own PID
+(as reported by
+.BR getpid ()),
+which would break many applications and libraries.
+.P
+To put things another way:
+a process's PID namespace membership is determined when the process is created
+and cannot be changed thereafter.
+Among other things, this means that the parental relationship
+between processes mirrors the parental relationship between PID namespaces:
+the parent of a process is either in the same namespace
+or resides in the immediate parent PID namespace.
+.P
+A process may call
+.BR unshare (2)
+with the
+.B CLONE_NEWPID
+flag only once.
+After it has performed this operation, its
+.IR /proc/ pid /ns/pid_for_children
+symbolic link will be empty until the first child is created in the namespace.
+.\"
+.\" ============================================================
+.\"
+.SS Adoption of orphaned children
+When a child process becomes orphaned, it is reparented to the "init"
+process in the PID namespace of its parent
+(unless one of the nearer ancestors of the parent employed the
+.BR prctl (2)
+.B PR_SET_CHILD_SUBREAPER
+command to mark itself as the reaper of orphaned descendant processes).
+Note that because of the
+.BR setns (2)
+and
+.BR unshare (2)
+semantics described above, this may be the "init" process in the PID
+namespace that is the
+.I parent
+of the child's PID namespace,
+rather than the "init" process in the child's own PID namespace.
+.\" Furthermore, by definition, the parent of the "init" process
+.\" of a PID namespace resides in the parent PID namespace.
+.\"
+.\" ============================================================
+.\"
+.SS Compatibility of CLONE_NEWPID with other CLONE_* flags
+In current versions of Linux,
+.B CLONE_NEWPID
+can't be combined with
+.BR CLONE_THREAD .
+Threads are required to be in the same PID namespace such that
+the threads in a process can send signals to each other.
+Similarly, it must be possible to see all of the threads
+of a process in the
+.BR proc (5)
+filesystem.
+Additionally, if two threads were in different PID
+namespaces, the process ID of the process sending a signal
+could not be meaningfully encoded when a signal is sent
+(see the description of the
+.I siginfo_t
+type in
+.BR sigaction (2)).
+Since this is computed when a signal is enqueued,
+a signal queue shared by processes in multiple PID namespaces
+would defeat that.
+.P
+.\" Note these restrictions were all introduced in
+.\" 8382fcac1b813ad0a4e68a838fc7ae93fa39eda0
+.\" when CLONE_NEWPID|CLONE_VM was disallowed
+In earlier versions of Linux,
+.B CLONE_NEWPID
+was additionally disallowed (failing with the error
+.BR EINVAL )
+in combination with
+.B CLONE_SIGHAND
+.\" (restriction lifted in faf00da544045fdc1454f3b9e6d7f65c841de302)
+(before Linux 4.3) as well as
+.\" (restriction lifted in e79f525e99b04390ca4d2366309545a836c03bf1)
+.B CLONE_VM
+(before Linux 3.12).
+The changes that lifted these restrictions have also been ported to
+earlier stable kernels.
+.\"
+.\" ============================================================
+.\"
+.SS /proc and PID namespaces
+A
+.I /proc
+filesystem shows (in the
+.IR /proc/ pid
+directories) only processes visible in the PID namespace
+of the process that performed the mount, even if the
+.I /proc
+filesystem is viewed from processes in other namespaces.
+.P
+After creating a new PID namespace,
+it is useful for the child to change its root directory
+and mount a new procfs instance at
+.I /proc
+so that tools such as
+.BR ps (1)
+work correctly.
+If a new mount namespace is simultaneously created by including
+.B  CLONE_NEWNS
+in the
+.I flags
+argument of
+.BR clone (2)
+or
+.BR unshare (2),
+then it isn't necessary to change the root directory:
+a new procfs instance can be mounted directly over
+.IR /proc .
+.P
+From a shell, the command to mount
+.I /proc
+is:
+.P
+.in +4n
+.EX
+$ mount \-t proc proc /proc
+.EE
+.in
+.P
+Calling
+.BR readlink (2)
+on the path
+.I /proc/self
+yields the process ID of the caller in the PID namespace of the procfs mount
+(i.e., the PID namespace of the process that mounted the procfs).
+This can be useful for introspection purposes,
+when a process wants to discover its PID in other namespaces.
+.\"
+.\" ============================================================
+.\"
+.SS /proc files
+.TP
+.BR /proc/sys/kernel/ns_last_pid " (since Linux 3.3)"
+.\" commit b8f566b04d3cddd192cfd2418ae6d54ac6353792
+This file
+(which is virtualized per PID namespace)
+displays the last PID that was allocated in this PID namespace.
+When the next PID is allocated,
+the kernel will search for the lowest unallocated PID
+that is greater than this value,
+and when this file is subsequently read it will show that PID.
+.IP
+This file is writable by a process that has the
+.B CAP_SYS_ADMIN
+or (since Linux 5.9)
+.B CAP_CHECKPOINT_RESTORE
+capability inside the user namespace that owns the PID namespace.
+.\" This ability is necessary to support checkpoint restore in user-space
+This makes it possible to determine the PID that is allocated
+to the next process that is created inside this PID namespace.
+.\"
+.\" ============================================================
+.\"
+.SS Miscellaneous
+When a process ID is passed over a UNIX domain socket to a
+process in a different PID namespace (see the description of
+.B SCM_CREDENTIALS
+in
+.BR unix (7)),
+it is translated into the corresponding PID value in
+the receiving process's PID namespace.
+.SH STANDARDS
+Linux.
+.SH EXAMPLES
+See
+.BR user_namespaces (7).
+.SH SEE ALSO
+.BR clone (2),
+.BR reboot (2),
+.BR setns (2),
+.BR unshare (2),
+.BR proc (5),
+.BR capabilities (7),
+.BR credentials (7),
+.BR mount_namespaces (7),
+.BR namespaces (7),
+.BR user_namespaces (7),
+.BR switch_root (8)
diff --git a/man/man7/pipe.7 b/man/man7/pipe.7
new file mode 100644
index 000000000..d1fad9974
--- /dev/null
+++ b/man/man7/pipe.7
@@ -0,0 +1,407 @@
+.\" Copyright (C) 2005 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pipe 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pipe \- overview of pipes and FIFOs
+.SH DESCRIPTION
+Pipes and FIFOs (also known as named pipes)
+provide a unidirectional interprocess communication channel.
+A pipe has a
+.I read end
+and a
+.IR "write end" .
+Data written to the write end of a pipe can be read
+from the read end of the pipe.
+.P
+A pipe is created using
+.BR pipe (2),
+which creates a new pipe and returns two file descriptors,
+one referring to the read end of the pipe,
+the other referring to the write end.
+Pipes can be used to create a communication channel between related
+processes; see
+.BR pipe (2)
+for an example.
+.P
+A FIFO (short for First In First Out) has a name within the filesystem
+(created using
+.BR mkfifo (3)),
+and is opened using
+.BR open (2).
+Any process may open a FIFO, assuming the file permissions allow it.
+The read end is opened using the
+.B O_RDONLY
+flag; the write end is opened using the
+.B O_WRONLY
+flag.
+See
+.BR fifo (7)
+for further details.
+.IR Note :
+although FIFOs have a pathname in the filesystem,
+I/O on FIFOs does not involve operations on the underlying device
+(if there is one).
+.SS I/O on pipes and FIFOs
+The only difference between pipes and FIFOs is the manner in which
+they are created and opened.
+Once these tasks have been accomplished,
+I/O on pipes and FIFOs has exactly the same semantics.
+.P
+If a process attempts to read from an empty pipe, then
+.BR read (2)
+will block until data is available.
+If a process attempts to write to a full pipe (see below), then
+.BR write (2)
+blocks until sufficient data has been read from the pipe
+to allow the write to complete.
+.P
+Nonblocking I/O is possible by using the
+.BR fcntl (2)
+.B F_SETFL
+operation to enable the
+.B O_NONBLOCK
+open file status flag or by opening a
+.BR fifo (7)
+with
+.BR O_NONBLOCK .
+If any process has the pipe open for writing, reads fail with
+.BR EAGAIN ;
+otherwise\[em]with no potential writers\[em]reads succeed and return empty.
+.P
+The communication channel provided by a pipe is a
+.IR "byte stream" :
+there is no concept of message boundaries.
+.P
+If all file descriptors referring to the write end of a pipe
+have been closed, then an attempt to
+.BR read (2)
+from the pipe will see end-of-file
+.RB ( read (2)
+will return 0).
+If all file descriptors referring to the read end of a pipe
+have been closed, then a
+.BR write (2)
+will cause a
+.B SIGPIPE
+signal to be generated for the calling process.
+If the calling process is ignoring this signal, then
+.BR write (2)
+fails with the error
+.BR EPIPE .
+An application that uses
+.BR pipe (2)
+and
+.BR fork (2)
+should use suitable
+.BR close (2)
+calls to close unnecessary duplicate file descriptors;
+this ensures that end-of-file and
+.BR SIGPIPE / EPIPE
+are delivered when appropriate.
+.P
+It is not possible to apply
+.BR lseek (2)
+to a pipe.
+.SS Pipe capacity
+A pipe has a limited capacity.
+If the pipe is full, then a
+.BR write (2)
+will block or fail, depending on whether the
+.B O_NONBLOCK
+flag is set (see below).
+Different implementations have different limits for the pipe capacity.
+Applications should not rely on a particular capacity:
+an application should be designed so that a reading process consumes data
+as soon as it is available,
+so that a writing process does not remain blocked.
+.P
+Before Linux 2.6.11, the capacity of a pipe was the same as
+the system page size (e.g., 4096 bytes on i386).
+Since Linux 2.6.11, the pipe capacity is 16 pages
+(i.e., 65,536 bytes in a system with a page size of 4096 bytes).
+Since Linux 2.6.35, the default pipe capacity is 16 pages,
+but the capacity can be queried and set using the
+.BR fcntl (2)
+.B F_GETPIPE_SZ
+and
+.B F_SETPIPE_SZ
+operations.
+See
+.BR fcntl (2)
+for more information.
+.P
+The following
+.BR ioctl (2)
+operation, which can be applied to a file descriptor
+that refers to either end of a pipe,
+places a count of the number of unread bytes in the pipe in the
+.I int
+buffer pointed to by the final argument of the call:
+.P
+.in +4n
+.EX
+ioctl(fd, FIONREAD, &nbytes);
+.EE
+.in
+.P
+The
+.B FIONREAD
+operation is not specified in any standard,
+but is provided on many implementations.
+.\"
+.SS /proc files
+On Linux, the following files control how much memory can be used for pipes:
+.TP
+.IR /proc/sys/fs/pipe\-max\-pages " (only in Linux 2.6.34)"
+.\" commit b492e95be0ae672922f4734acf3f5d35c30be948
+An upper limit, in pages, on the capacity that an unprivileged user
+(one without the
+.B CAP_SYS_RESOURCE
+capability)
+can set for a pipe.
+.IP
+The default value for this limit is 16 times the default pipe capacity
+(see above); the lower limit is two pages.
+.IP
+This interface was removed in Linux 2.6.35, in favor of
+.IR /proc/sys/fs/pipe\-max\-size .
+.TP
+.IR /proc/sys/fs/pipe\-max\-size " (since Linux 2.6.35)"
+.\" commit ff9da691c0498ff81fdd014e7a0731dab2337dac
+The maximum size (in bytes) of individual pipes that can be set
+.\" This limit is not checked on pipe creation, where the capacity is
+.\" always PIPE_DEF_BUFS, regardless of pipe-max-size
+by users without the
+.B CAP_SYS_RESOURCE
+capability.
+The value assigned to this file may be rounded upward,
+to reflect the value actually employed for a convenient implementation.
+To determine the rounded-up value,
+display the contents of this file after assigning a value to it.
+.IP
+The default value for this file is 1048576 (1\ MiB).
+The minimum value that can be assigned to this file is the system page size.
+Attempts to set a limit less than the page size cause
+.BR write (2)
+to fail with the error
+.BR EINVAL .
+.IP
+Since Linux 4.9,
+.\" commit 086e774a57fba4695f14383c0818994c0b31da7c
+the value on this file also acts as a ceiling on the default capacity
+of a new pipe or newly opened FIFO.
+.TP
+.IR /proc/sys/fs/pipe\-user\-pages\-hard " (since Linux 4.5)"
+.\" commit 759c01142a5d0f364a462346168a56de28a80f52
+The hard limit on the total size (in pages) of all pipes created or set by
+a single unprivileged user (i.e., one with neither the
+.B CAP_SYS_RESOURCE
+nor the
+.B CAP_SYS_ADMIN
+capability).
+So long as the total number of pages allocated to pipe buffers
+for this user is at this limit,
+attempts to create new pipes will be denied,
+and attempts to increase a pipe's capacity will be denied.
+.IP
+When the value of this limit is zero (which is the default),
+no hard limit is applied.
+.\" The default was chosen to avoid breaking existing applications that
+.\" make intensive use of pipes (e.g., for splicing).
+.TP
+.IR /proc/sys/fs/pipe\-user\-pages\-soft " (since Linux 4.5)"
+.\" commit 759c01142a5d0f364a462346168a56de28a80f52
+The soft limit on the total size (in pages) of all pipes created or set by
+a single unprivileged user (i.e., one with neither the
+.B CAP_SYS_RESOURCE
+nor the
+.B CAP_SYS_ADMIN
+capability).
+So long as the total number of pages allocated to pipe buffers
+for this user is at this limit,
+individual pipes created by a user will be limited to one page,
+and attempts to increase a pipe's capacity will be denied.
+.IP
+When the value of this limit is zero, no soft limit is applied.
+The default value for this file is 16384,
+which permits creating up to 1024 pipes with the default capacity.
+.P
+Before Linux 4.9, some bugs affected the handling of the
+.I pipe\-user\-pages\-soft
+and
+.I pipe\-user\-pages\-hard
+limits; see BUGS.
+.\"
+.SS PIPE_BUF
+POSIX.1 says that writes of less than
+.B PIPE_BUF
+bytes must be atomic: the output data is written to the pipe as a
+contiguous sequence.
+Writes of more than
+.B PIPE_BUF
+bytes may be nonatomic: the kernel may interleave the data
+with data written by other processes.
+POSIX.1 requires
+.B PIPE_BUF
+to be at least 512 bytes.
+(On Linux,
+.B PIPE_BUF
+is 4096 bytes.)
+The precise semantics depend on whether the file descriptor is nonblocking
+.RB ( O_NONBLOCK ),
+whether there are multiple writers to the pipe, and on
+.IR n ,
+the number of bytes to be written:
+.TP
+\fBO_NONBLOCK\fP disabled, \fIn\fP <= \fBPIPE_BUF\fP
+All
+.I n
+bytes are written atomically;
+.BR write (2)
+may block if there is not room for
+.I n
+bytes to be written immediately
+.TP
+\fBO_NONBLOCK\fP enabled, \fIn\fP <= \fBPIPE_BUF\fP
+If there is room to write
+.I n
+bytes to the pipe, then
+.BR write (2)
+succeeds immediately, writing all
+.I n
+bytes; otherwise
+.BR write (2)
+fails, with
+.I errno
+set to
+.BR EAGAIN .
+.TP
+\fBO_NONBLOCK\fP disabled, \fIn\fP > \fBPIPE_BUF\fP
+The write is nonatomic: the data given to
+.BR write (2)
+may be interleaved with
+.BR write (2)s
+by other process;
+the
+.BR write (2)
+blocks until
+.I n
+bytes have been written.
+.TP
+\fBO_NONBLOCK\fP enabled, \fIn\fP > \fBPIPE_BUF\fP
+If the pipe is full, then
+.BR write (2)
+fails, with
+.I errno
+set to
+.BR EAGAIN .
+Otherwise, from 1 to
+.I n
+bytes may be written (i.e., a "partial write" may occur;
+the caller should check the return value from
+.BR write (2)
+to see how many bytes were actually written),
+and these bytes may be interleaved with writes by other processes.
+.SS Open file status flags
+The only open file status flags that can be meaningfully applied to
+a pipe or FIFO are
+.B O_NONBLOCK
+and
+.BR O_ASYNC .
+.P
+Setting the
+.B O_ASYNC
+flag for the read end of a pipe causes a signal
+.RB ( SIGIO
+by default) to be generated when new input becomes available on the pipe.
+The target for delivery of signals must be set using the
+.BR fcntl (2)
+.B F_SETOWN
+command.
+On Linux,
+.B O_ASYNC
+is supported for pipes and FIFOs only since Linux 2.6.
+.SS Portability notes
+On some systems (but not Linux), pipes are bidirectional:
+data can be transmitted in both directions between the pipe ends.
+POSIX.1 requires only unidirectional pipes.
+Portable applications should avoid reliance on
+bidirectional pipe semantics.
+.SS BUGS
+Before Linux 4.9, some bugs affected the handling of the
+.I pipe\-user\-pages\-soft
+and
+.I pipe\-user\-pages\-hard
+limits when using the
+.BR fcntl (2)
+.B F_SETPIPE_SZ
+operation to change a pipe's capacity:
+.\" These bugs where remedied by a series of patches, in particular,
+.\" commit b0b91d18e2e97b741b294af9333824ecc3fadfd8 and
+.\" commit a005ca0e6813e1d796a7422a7e31d8b8d6555df1
+.IP (a) 5
+When increasing the pipe capacity, the checks against the soft and
+hard limits were made against existing consumption,
+and excluded the memory required for the increased pipe capacity.
+The new increase in pipe capacity could then push the total
+memory used by the user for pipes (possibly far) over a limit.
+(This could also trigger the problem described next.)
+.IP
+Starting with Linux 4.9,
+the limit checking includes the memory required for the new pipe capacity.
+.IP (b)
+The limit checks were performed even when the new pipe capacity was
+less than the existing pipe capacity.
+This could lead to problems if a user set a large pipe capacity,
+and then the limits were lowered, with the result that the user could
+no longer decrease the pipe capacity.
+.IP
+Starting with Linux 4.9, checks against the limits
+are performed only when increasing a pipe's capacity;
+an unprivileged user can always decrease a pipe's capacity.
+.IP (c)
+The accounting and checking against the limits were done as follows:
+.RS
+.IP (1) 5
+.PD 0
+Test whether the user has exceeded the limit.
+.IP (2)
+Make the new pipe buffer allocation.
+.IP (3)
+Account new allocation against the limits.
+.PD
+.RE
+.IP
+This was racey.
+Multiple processes could pass point (1) simultaneously,
+and then allocate pipe buffers that were accounted for only in step (3),
+with the result that the user's pipe buffer
+allocation could be pushed over the limit.
+.IP
+Starting with Linux 4.9,
+the accounting step is performed before doing the allocation,
+and the operation fails if the limit would be exceeded.
+.P
+Before Linux 4.9, bugs similar to points (a) and (c) could also occur
+when the kernel allocated memory for a new pipe buffer;
+that is, when calling
+.BR pipe (2)
+and when opening a previously unopened FIFO.
+.SH SEE ALSO
+.BR mkfifo (1),
+.BR dup (2),
+.BR fcntl (2),
+.BR open (2),
+.BR pipe (2),
+.BR poll (2),
+.BR select (2),
+.BR socketpair (2),
+.BR splice (2),
+.BR stat (2),
+.BR tee (2),
+.BR vmsplice (2),
+.BR mkfifo (3),
+.BR epoll (7),
+.BR fifo (7)
diff --git a/man/man7/pkeys.7 b/man/man7/pkeys.7
new file mode 100644
index 000000000..4fb814c99
--- /dev/null
+++ b/man/man7/pkeys.7
@@ -0,0 +1,237 @@
+.\" Copyright (C) 2016 Intel Corporation
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pkeys 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pkeys \- overview of Memory Protection Keys
+.SH DESCRIPTION
+Memory Protection Keys (pkeys) are an extension to existing
+page-based memory permissions.
+Normal page permissions using
+page tables require expensive system calls and TLB invalidations
+when changing permissions.
+Memory Protection Keys provide a mechanism for changing
+protections without requiring modification of the page tables on
+every permission change.
+.P
+To use pkeys, software must first "tag" a page in the page tables
+with a pkey.
+After this tag is in place, an application only has
+to change the contents of a register in order to remove write
+access, or all access to a tagged page.
+.P
+Protection keys work in conjunction with the existing
+.BR PROT_READ ,
+.BR PROT_WRITE ,
+and
+.B PROT_EXEC
+permissions passed to system calls such as
+.BR mprotect (2)
+and
+.BR mmap (2),
+but always act to further restrict these traditional permission
+mechanisms.
+.P
+If a process performs an access that violates pkey
+restrictions, it receives a
+.B SIGSEGV
+signal.
+See
+.BR sigaction (2)
+for details of the information available with that signal.
+.P
+To use the pkeys feature, the processor must support it, and the kernel
+must contain support for the feature on a given processor.
+As of early 2016 only future Intel x86 processors are supported,
+and this hardware supports 16 protection keys in each process.
+However, pkey 0 is used as the default key, so a maximum of 15
+are available for actual application use.
+The default key is assigned to any memory region for which a
+pkey has not been explicitly assigned via
+.BR pkey_mprotect (2).
+.P
+Protection keys have the potential to add a layer of security and
+reliability to applications.
+But they have not been primarily designed as
+a security feature.
+For instance, WRPKRU is a completely unprivileged
+instruction, so pkeys are useless in any case that an attacker controls
+the PKRU register or can execute arbitrary instructions.
+.P
+Applications should be very careful to ensure that they do not "leak"
+protection keys.
+For instance, before calling
+.BR pkey_free (2),
+the application should be sure that no memory has that pkey assigned.
+If the application left the freed pkey assigned, a future user of
+that pkey might inadvertently change the permissions of an unrelated
+data structure, which could impact security or stability.
+The kernel currently allows in-use pkeys to have
+.BR pkey_free (2)
+called on them because it would have processor or memory performance
+implications to perform the additional checks needed to disallow it.
+Implementation of the necessary checks is left up to applications.
+Applications may implement these checks by searching the
+.IR /proc/ pid /smaps
+file for memory regions with the pkey assigned.
+Further details can be found in
+.BR proc (5).
+.P
+Any application wanting to use protection keys needs to be able
+to function without them.
+They might be unavailable because the hardware that the
+application runs on does not support them, the kernel code does
+not contain support, the kernel support has been disabled, or
+because the keys have all been allocated, perhaps by a library
+the application is using.
+It is recommended that applications wanting to use protection
+keys should simply call
+.BR pkey_alloc (2)
+and test whether the call succeeds,
+instead of attempting to detect support for the
+feature in any other way.
+.P
+Although unnecessary, hardware support for protection keys may be
+enumerated with the
+.I cpuid
+instruction.
+Details of how to do this can be found in the Intel Software
+Developers Manual.
+The kernel performs this enumeration and exposes the information in
+.I /proc/cpuinfo
+under the "flags" field.
+The string "pku" in this field indicates hardware support for protection
+keys and the string "ospke" indicates that the kernel contains and has
+enabled protection keys support.
+.P
+Applications using threads and protection keys should be especially
+careful.
+Threads inherit the protection key rights of the parent at the time
+of the
+.BR clone (2),
+system call.
+Applications should either ensure that their own permissions are
+appropriate for child threads at the time when
+.BR clone (2)
+is called, or ensure that each child thread can perform its
+own initialization of protection key rights.
+.\"
+.SS Signal Handler Behavior
+Each time a signal handler is invoked (including nested signals), the
+thread is temporarily given a new, default set of protection key rights
+that override the rights from the interrupted context.
+This means that applications must re-establish their desired protection
+key rights upon entering a signal handler if the desired rights differ
+from the defaults.
+The rights of any interrupted context are restored when the signal
+handler returns.
+.P
+This signal behavior is unusual and is due to the fact that the x86 PKRU
+register (which stores protection key access rights) is managed with the
+same hardware mechanism (XSAVE) that manages floating-point registers.
+The signal behavior is the same as that of floating-point registers.
+.\"
+.SS Protection Keys system calls
+The Linux kernel implements the following pkey-related system calls:
+.BR pkey_mprotect (2),
+.BR pkey_alloc (2),
+and
+.BR pkey_free (2).
+.P
+The Linux pkey system calls are available only if the kernel was
+configured and built with the
+.B CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+option.
+.SH EXAMPLES
+The program below allocates a page of memory with read and write permissions.
+It then writes some data to the memory and successfully reads it
+back.
+After that, it attempts to allocate a protection key and
+disallows access to the page by using the WRPKRU instruction.
+It then tries to access the page,
+which we now expect to cause a fatal signal to the application.
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out"
+buffer contains: 73
+about to read buffer again...
+Segmentation fault (core dumped)
+.EE
+.in
+.SS Program source
+\&
+.EX
+#define _GNU_SOURCE
+#include <err.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+\&
+int
+main(void)
+{
+    int status;
+    int pkey;
+    int *buffer;
+\&
+    /*
+     * Allocate one page of memory.
+     */
+    buffer = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE,
+                  MAP_ANONYMOUS | MAP_PRIVATE, \-1, 0);
+    if (buffer == MAP_FAILED)
+        err(EXIT_FAILURE, "mmap");
+\&
+    /*
+     * Put some random data into the page (still OK to touch).
+     */
+    *buffer = __LINE__;
+    printf("buffer contains: %d\en", *buffer);
+\&
+    /*
+     * Allocate a protection key:
+     */
+    pkey = pkey_alloc(0, 0);
+    if (pkey == \-1)
+        err(EXIT_FAILURE, "pkey_alloc");
+\&
+    /*
+     * Disable access to any memory with "pkey" set,
+     * even though there is none right now.
+     */
+    status = pkey_set(pkey, PKEY_DISABLE_ACCESS);
+    if (status)
+        err(EXIT_FAILURE, "pkey_set");
+\&
+    /*
+     * Set the protection key on "buffer".
+     * Note that it is still read/write as far as mprotect() is
+     * concerned and the previous pkey_set() overrides it.
+     */
+    status = pkey_mprotect(buffer, getpagesize(),
+                           PROT_READ | PROT_WRITE, pkey);
+    if (status == \-1)
+        err(EXIT_FAILURE, "pkey_mprotect");
+\&
+    printf("about to read buffer again...\en");
+\&
+    /*
+     * This will crash, because we have disallowed access.
+     */
+    printf("buffer contains: %d\en", *buffer);
+\&
+    status = pkey_free(pkey);
+    if (status == \-1)
+        err(EXIT_FAILURE, "pkey_free");
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR pkey_alloc (2),
+.BR pkey_free (2),
+.BR pkey_mprotect (2),
+.BR sigaction (2)
diff --git a/man/man7/posixoptions.7 b/man/man7/posixoptions.7
new file mode 100644
index 000000000..8ca4df0ea
--- /dev/null
+++ b/man/man7/posixoptions.7
@@ -0,0 +1,1014 @@
+.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH posixoptions 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+posixoptions \- optional parts of the POSIX standard
+.SH DESCRIPTION
+The POSIX standard (the information below is from POSIX.1-2001)
+describes a set of behaviors and interfaces for a compliant system.
+However, many interfaces are optional and there are feature test macros
+to test the availability of interfaces at compile time, and functions
+.BR sysconf (3),
+.BR fpathconf (3),
+.BR pathconf (3),
+.BR confstr (3)
+to do this at run time.
+From shell scripts one can use
+.BR getconf (1).
+For more detail, see
+.BR sysconf (3).
+.P
+We give the name of the POSIX abbreviation, the option, the name of the
+.BR sysconf (3)
+parameter used to inquire about the option, and possibly
+a very short description.
+Much more precise detail can be found in the POSIX standard itself,
+versions of which can nowadays be accessed freely on the web.
+.SS ADV - _POSIX_ADVISORY_INFO - _SC_ADVISORY_INFO
+The following advisory functions are present:
+.P
+.nf
+.in +4n
+.IR posix_fadvise ()
+.IR posix_fallocate ()
+.IR posix_memalign ()
+.IR posix_madvise ()
+.in
+.fi
+.SS AIO - _POSIX_ASYNCHRONOUS_IO - _SC_ASYNCHRONOUS_IO
+The header
+.I <aio.h>
+is present.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR aio_cancel ()
+.IR aio_error ()
+.IR aio_fsync ()
+.IR aio_read ()
+.IR aio_return ()
+.IR aio_suspend ()
+.IR aio_write ()
+.IR lio_listio ()
+.in
+.fi
+.SS BAR - _POSIX_BARRIERS - _SC_BARRIERS
+This option implies the
+.B _POSIX_THREADS
+and
+.B _POSIX_THREAD_SAFE_FUNCTIONS
+options.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR pthread_barrier_destroy ()
+.IR pthread_barrier_init ()
+.IR pthread_barrier_wait ()
+.IR pthread_barrierattr_destroy ()
+.IR pthread_barrierattr_init ()
+.in
+.fi
+.\" .SS BE
+.\" Batch environment.
+.\" .SS CD
+.\" C development.
+.SS --- - POSIX_CHOWN_RESTRICTED
+If this option is in effect (as it always is under POSIX.1-2001),
+then only root may change the owner of a file, and nonroot can
+set the group of a file only to one of the groups it belongs to.
+This affects the following functions:
+.P
+.nf
+.in +4n
+.IR chown ()
+.IR fchown ()
+.in
+.fi
+.\" What about lchown() ?
+.SS CS - _POSIX_CLOCK_SELECTION - _SC_CLOCK_SELECTION
+This option implies the
+.B _POSIX_TIMERS
+option.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR pthread_condattr_getclock ()
+.IR pthread_condattr_setclock ()
+.IR clock_nanosleep ()
+.in
+.fi
+.P
+If
+.B CLOCK_REALTIME
+is changed by the function
+.IR clock_settime (),
+then this affects all timers set for an absolute time.
+.SS CPT - _POSIX_CPUTIME - _SC_CPUTIME
+The
+.B CLOCK_PROCESS_CPUTIME_ID
+clock ID is supported.
+The initial value of this clock is 0 for each process.
+This option implies the
+.B _POSIX_TIMERS
+option.
+The function
+.IR clock_getcpuclockid ()
+is present.
+.\" .SS FD
+.\" Fortran development
+.\" .SS FR
+.\" Fortran runtime
+.SS --- - _POSIX_FILE_LOCKING - _SC_FILE_LOCKING
+This option has been deleted.
+Not in final XPG6.
+.SS FSC - _POSIX_FSYNC - _SC_FSYNC
+The function
+.IR fsync ()
+is present.
+.SS IP6 - _POSIX_IPV6 - _SC_IPV6
+Internet Protocol Version 6 is supported.
+.SS --- - _POSIX_JOB_CONTROL - _SC_JOB_CONTROL
+If this option is in effect (as it always is under POSIX.1-2001),
+then the system implements POSIX-style job control,
+and the following functions are present:
+.P
+.nf
+.in +4n
+.IR setpgid ()
+.IR tcdrain ()
+.IR tcflush ()
+.IR tcgetpgrp ()
+.IR tcsendbreak ()
+.IR tcsetattr ()
+.IR tcsetpgrp ()
+.in
+.fi
+.SS MF - _POSIX_MAPPED_FILES - _SC_MAPPED_FILES
+Shared memory is supported.
+The include file
+.I <sys/mman.h>
+is present.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR mmap ()
+.IR msync ()
+.IR munmap ()
+.in
+.fi
+.SS ML - _POSIX_MEMLOCK - _SC_MEMLOCK
+Shared memory can be locked into core.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR mlockall ()
+.IR munlockall ()
+.in
+.fi
+.SS MR/MLR - _POSIX_MEMLOCK_RANGE - _SC_MEMLOCK_RANGE
+More precisely, ranges can be locked into core.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR mlock ()
+.IR munlock ()
+.in
+.fi
+.SS MPR - _POSIX_MEMORY_PROTECTION - _SC_MEMORY_PROTECTION
+The function
+.IR mprotect ()
+is present.
+.SS MSG - _POSIX_MESSAGE_PASSING - _SC_MESSAGE_PASSING
+The include file
+.I <mqueue.h>
+is present.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR mq_close ()
+.IR mq_getattr ()
+.IR mq_notify ()
+.IR mq_open ()
+.IR mq_receive ()
+.IR mq_send ()
+.IR mq_setattr ()
+.IR mq_unlink ()
+.in
+.fi
+.SS MON - _POSIX_MONOTONIC_CLOCK - _SC_MONOTONIC_CLOCK
+.B CLOCK_MONOTONIC
+is supported.
+This option implies the
+.B _POSIX_TIMERS
+option.
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR aio_suspend ()
+.IR clock_getres ()
+.IR clock_gettime ()
+.IR clock_settime ()
+.IR timer_create ()
+.in
+.fi
+.SS --- - _POSIX_MULTI_PROCESS - _SC_MULTI_PROCESS
+This option has been deleted.
+Not in final XPG6.
+.\" .SS MX
+.\" IEC 60559 Floating-Point Option.
+.SS --- - _POSIX_NO_TRUNC
+If this option is in effect (as it always is under POSIX.1-2001),
+then pathname components longer than
+.B NAME_MAX
+are not truncated,
+but give an error.
+This property may be dependent on the path prefix of the component.
+.SS PIO - _POSIX_PRIORITIZED_IO - _SC_PRIORITIZED_IO
+This option says that one can specify priorities for asynchronous I/O.
+This affects the functions
+.P
+.nf
+.in +4n
+.IR aio_read ()
+.IR aio_write ()
+.in
+.fi
+.SS PS - _POSIX_PRIORITY_SCHEDULING - _SC_PRIORITY_SCHEDULING
+The include file
+.I <sched.h>
+is present.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR sched_get_priority_max ()
+.IR sched_get_priority_min ()
+.IR sched_getparam ()
+.IR sched_getscheduler ()
+.IR sched_rr_get_interval ()
+.IR sched_setparam ()
+.IR sched_setscheduler ()
+.IR sched_yield ()
+.in
+.fi
+.P
+If also
+.B _POSIX_SPAWN
+is in effect, then the following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_spawnattr_getschedparam ()
+.IR posix_spawnattr_getschedpolicy ()
+.IR posix_spawnattr_setschedparam ()
+.IR posix_spawnattr_setschedpolicy ()
+.in
+.fi
+.SS RS - _POSIX_RAW_SOCKETS
+Raw sockets are supported.
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR getsockopt ()
+.IR setsockopt ()
+.in
+.fi
+.SS --- - _POSIX_READER_WRITER_LOCKS - _SC_READER_WRITER_LOCKS
+This option implies the
+.B _POSIX_THREADS
+option.
+Conversely,
+under POSIX.1-2001 the
+.B _POSIX_THREADS
+option implies this option.
+.P
+The following functions are present:
+.P
+.in +4n
+.nf
+.IR pthread_rwlock_destroy ()
+.IR pthread_rwlock_init ()
+.IR pthread_rwlock_rdlock ()
+.IR pthread_rwlock_tryrdlock ()
+.IR pthread_rwlock_trywrlock ()
+.IR pthread_rwlock_unlock ()
+.IR pthread_rwlock_wrlock ()
+.IR pthread_rwlockattr_destroy ()
+.IR pthread_rwlockattr_init ()
+.in
+.fi
+.SS RTS - _POSIX_REALTIME_SIGNALS - _SC_REALTIME_SIGNALS
+Realtime signals are supported.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR sigqueue ()
+.IR sigtimedwait ()
+.IR sigwaitinfo ()
+.in
+.fi
+.SS --- - _POSIX_REGEXP - _SC_REGEXP
+If this option is in effect (as it always is under POSIX.1-2001),
+then POSIX regular expressions are supported
+and the following functions are present:
+.P
+.nf
+.in +4n
+.IR regcomp ()
+.IR regerror ()
+.IR regexec ()
+.IR regfree ()
+.in
+.fi
+.SS --- - _POSIX_SAVED_IDS - _SC_SAVED_IDS
+If this option is in effect (as it always is under POSIX.1-2001),
+then a process has a saved set-user-ID and a saved set-group-ID.
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR exec ()
+.IR kill ()
+.IR seteuid ()
+.IR setegid ()
+.IR setgid ()
+.IR setuid ()
+.in
+.fi
+.\" .SS SD
+.\" Software development
+.SS SEM - _POSIX_SEMAPHORES - _SC_SEMAPHORES
+The include file
+.I <semaphore.h>
+is present.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR sem_close ()
+.IR sem_destroy ()
+.IR sem_getvalue ()
+.IR sem_init ()
+.IR sem_open ()
+.IR sem_post ()
+.IR sem_trywait ()
+.IR sem_unlink ()
+.IR sem_wait ()
+.in
+.fi
+.SS SHM - _POSIX_SHARED_MEMORY_OBJECTS - _SC_SHARED_MEMORY_OBJECTS
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR mmap ()
+.IR munmap ()
+.IR shm_open ()
+.IR shm_unlink ()
+.in
+.fi
+.SS --- - _POSIX_SHELL - _SC_SHELL
+If this option is in effect (as it always is under POSIX.1-2001),
+the function
+.IR system ()
+is present.
+.SS SPN - _POSIX_SPAWN - _SC_SPAWN
+This option describes support for process creation in a context where
+it is difficult or impossible to use
+.IR fork (),
+for example, because no MMU is present.
+.P
+If
+.B _POSIX_SPAWN
+is in effect, then the include file
+.I <spawn.h>
+and the following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_spawn ()
+.IR posix_spawn_file_actions_addclose ()
+.IR posix_spawn_file_actions_adddup2 ()
+.IR posix_spawn_file_actions_addopen ()
+.IR posix_spawn_file_actions_destroy ()
+.IR posix_spawn_file_actions_init ()
+.IR posix_spawnattr_destroy ()
+.IR posix_spawnattr_getsigdefault ()
+.IR posix_spawnattr_getflags ()
+.IR posix_spawnattr_getpgroup ()
+.IR posix_spawnattr_getsigmask ()
+.IR posix_spawnattr_init ()
+.IR posix_spawnattr_setsigdefault ()
+.IR posix_spawnattr_setflags ()
+.IR posix_spawnattr_setpgroup ()
+.IR posix_spawnattr_setsigmask ()
+.IR posix_spawnp ()
+.in
+.fi
+.P
+If also
+.B _POSIX_PRIORITY_SCHEDULING
+is in effect, then
+the following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_spawnattr_getschedparam ()
+.IR posix_spawnattr_getschedpolicy ()
+.IR posix_spawnattr_setschedparam ()
+.IR posix_spawnattr_setschedpolicy ()
+.in
+.fi
+.SS SPI - _POSIX_SPIN_LOCKS - _SC_SPIN_LOCKS
+This option implies the
+.B _POSIX_THREADS
+and
+.B _POSIX_THREAD_SAFE_FUNCTIONS
+options.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR pthread_spin_destroy ()
+.IR pthread_spin_init ()
+.IR pthread_spin_lock ()
+.IR pthread_spin_trylock ()
+.IR pthread_spin_unlock ()
+.in -4n
+.fi
+.SS SS - _POSIX_SPORADIC_SERVER - _SC_SPORADIC_SERVER
+The scheduling policy
+.B SCHED_SPORADIC
+is supported.
+This option implies the
+.B _POSIX_PRIORITY_SCHEDULING
+option.
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR sched_setparam ()
+.IR sched_setscheduler ()
+.in
+.fi
+.SS SIO - _POSIX_SYNCHRONIZED_IO - _SC_SYNCHRONIZED_IO
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR open ()
+.IR msync ()
+.IR fsync ()
+.IR fdatasync ()
+.in
+.fi
+.SS TSA - _POSIX_THREAD_ATTR_STACKADDR - _SC_THREAD_ATTR_STACKADDR
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR pthread_attr_getstack ()
+.IR pthread_attr_getstackaddr ()
+.IR pthread_attr_setstack ()
+.IR pthread_attr_setstackaddr ()
+.in
+.fi
+.SS TSS - _POSIX_THREAD_ATTR_STACKSIZE - _SC_THREAD_ATTR_STACKSIZE
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR pthread_attr_getstack ()
+.IR pthread_attr_getstacksize ()
+.IR pthread_attr_setstack ()
+.IR pthread_attr_setstacksize ()
+.in
+.fi
+.SS TCT - _POSIX_THREAD_CPUTIME - _SC_THREAD_CPUTIME
+The clockID CLOCK_THREAD_CPUTIME_ID is supported.
+This option implies the
+.B _POSIX_TIMERS
+option.
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR pthread_getcpuclockid ()
+.IR clock_getres ()
+.IR clock_gettime ()
+.IR clock_settime ()
+.IR timer_create ()
+.in
+.fi
+.SS TPI - _POSIX_THREAD_PRIO_INHERIT - _SC_THREAD_PRIO_INHERIT
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR pthread_mutexattr_getprotocol ()
+.IR pthread_mutexattr_setprotocol ()
+.in
+.fi
+.SS TPP - _POSIX_THREAD_PRIO_PROTECT - _SC_THREAD_PRIO_PROTECT
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR pthread_mutex_getprioceiling ()
+.IR pthread_mutex_setprioceiling ()
+.IR pthread_mutexattr_getprioceiling ()
+.IR pthread_mutexattr_getprotocol ()
+.IR pthread_mutexattr_setprioceiling ()
+.IR pthread_mutexattr_setprotocol ()
+.in
+.fi
+.SS TPS - _POSIX_THREAD_PRIORITY_SCHEDULING - _SC_THREAD_PRIORITY_SCHEDULING
+If this option is in effect, the different threads inside a process
+can run with different priorities and/or different schedulers.
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR pthread_attr_getinheritsched ()
+.IR pthread_attr_getschedpolicy ()
+.IR pthread_attr_getscope ()
+.IR pthread_attr_setinheritsched ()
+.IR pthread_attr_setschedpolicy ()
+.IR pthread_attr_setscope ()
+.IR pthread_getschedparam ()
+.IR pthread_setschedparam ()
+.IR pthread_setschedprio ()
+.in
+.fi
+.SS TSH - _POSIX_THREAD_PROCESS_SHARED - _SC_THREAD_PROCESS_SHARED
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR pthread_barrierattr_getpshared ()
+.IR pthread_barrierattr_setpshared ()
+.IR pthread_condattr_getpshared ()
+.IR pthread_condattr_setpshared ()
+.IR pthread_mutexattr_getpshared ()
+.IR pthread_mutexattr_setpshared ()
+.IR pthread_rwlockattr_getpshared ()
+.IR pthread_rwlockattr_setpshared ()
+.in
+.fi
+.SS TSF - _POSIX_THREAD_SAFE_FUNCTIONS - _SC_THREAD_SAFE_FUNCTIONS
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR readdir_r ()
+.IR getgrgid_r ()
+.IR getgrnam_r ()
+.IR getpwnam_r ()
+.IR getpwuid_r ()
+.IR flockfile ()
+.IR ftrylockfile ()
+.IR funlockfile ()
+.IR getc_unlocked ()
+.IR getchar_unlocked ()
+.IR putc_unlocked ()
+.IR putchar_unlocked ()
+.IR rand_r ()
+.IR strerror_r ()
+.IR strtok_r ()
+.IR asctime_r ()
+.IR ctime_r ()
+.IR gmtime_r ()
+.IR localtime_r ()
+.in
+.fi
+.SS TSP - _POSIX_THREAD_SPORADIC_SERVER - _SC_THREAD_SPORADIC_SERVER
+This option implies the
+.B _POSIX_THREAD_PRIORITY_SCHEDULING
+option.
+The following functions are affected:
+.P
+.nf
+.in +4n
+.IR sched_getparam ()
+.IR sched_setparam ()
+.IR sched_setscheduler ()
+.in
+.fi
+.SS THR - _POSIX_THREADS - _SC_THREADS
+Basic support for POSIX threads is available.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR pthread_atfork ()
+.IR pthread_attr_destroy ()
+.IR pthread_attr_getdetachstate ()
+.IR pthread_attr_getschedparam ()
+.IR pthread_attr_init ()
+.IR pthread_attr_setdetachstate ()
+.IR pthread_attr_setschedparam ()
+.IR pthread_cancel ()
+.IR pthread_cleanup_push ()
+.IR pthread_cleanup_pop ()
+.IR pthread_cond_broadcast ()
+.IR pthread_cond_destroy ()
+.IR pthread_cond_init ()
+.IR pthread_cond_signal ()
+.IR pthread_cond_timedwait ()
+.IR pthread_cond_wait ()
+.IR pthread_condattr_destroy ()
+.IR pthread_condattr_init ()
+.IR pthread_create ()
+.IR pthread_detach ()
+.IR pthread_equal ()
+.IR pthread_exit ()
+.IR pthread_getspecific ()
+.IR pthread_join ()
+.IR pthread_key_create ()
+.IR pthread_key_delete ()
+.IR pthread_mutex_destroy ()
+.IR pthread_mutex_init ()
+.IR pthread_mutex_lock ()
+.IR pthread_mutex_trylock ()
+.IR pthread_mutex_unlock ()
+.IR pthread_mutexattr_destroy ()
+.IR pthread_mutexattr_init ()
+.IR pthread_once ()
+.IR pthread_rwlock_destroy ()
+.IR pthread_rwlock_init ()
+.IR pthread_rwlock_rdlock ()
+.IR pthread_rwlock_tryrdlock ()
+.IR pthread_rwlock_trywrlock ()
+.IR pthread_rwlock_unlock ()
+.IR pthread_rwlock_wrlock ()
+.IR pthread_rwlockattr_destroy ()
+.IR pthread_rwlockattr_init ()
+.IR pthread_self ()
+.IR pthread_setcancelstate ()
+.IR pthread_setcanceltype ()
+.IR pthread_setspecific ()
+.IR pthread_testcancel ()
+.in
+.fi
+.SS TMO - _POSIX_TIMEOUTS - _SC_TIMEOUTS
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR mq_timedreceive ()
+.IR mq_timedsend ()
+.IR pthread_mutex_timedlock ()
+.IR pthread_rwlock_timedrdlock ()
+.IR pthread_rwlock_timedwrlock ()
+.IR sem_timedwait ()
+.IR posix_trace_timedgetnext_event ()
+.in
+.fi
+.SS TMR - _POSIX_TIMERS - _SC_TIMERS
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR clock_getres ()
+.IR clock_gettime ()
+.IR clock_settime ()
+.IR nanosleep ()
+.IR timer_create ()
+.IR timer_delete ()
+.IR timer_gettime ()
+.IR timer_getoverrun ()
+.IR timer_settime ()
+.in
+.fi
+.SS TRC - _POSIX_TRACE - _SC_TRACE
+POSIX tracing is available.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_trace_attr_destroy ()
+.IR posix_trace_attr_getclockres ()
+.IR posix_trace_attr_getcreatetime ()
+.IR posix_trace_attr_getgenversion ()
+.IR posix_trace_attr_getmaxdatasize ()
+.IR posix_trace_attr_getmaxsystemeventsize ()
+.IR posix_trace_attr_getmaxusereventsize ()
+.IR posix_trace_attr_getname ()
+.IR posix_trace_attr_getstreamfullpolicy ()
+.IR posix_trace_attr_getstreamsize ()
+.IR posix_trace_attr_init ()
+.IR posix_trace_attr_setmaxdatasize ()
+.IR posix_trace_attr_setname ()
+.IR posix_trace_attr_setstreamsize ()
+.IR posix_trace_attr_setstreamfullpolicy ()
+.IR posix_trace_clear ()
+.IR posix_trace_create ()
+.IR posix_trace_event ()
+.IR posix_trace_eventid_equal ()
+.IR posix_trace_eventid_get_name ()
+.IR posix_trace_eventid_open ()
+.IR posix_trace_eventtypelist_getnext_id ()
+.IR posix_trace_eventtypelist_rewind ()
+.IR posix_trace_flush ()
+.IR posix_trace_get_attr ()
+.IR posix_trace_get_status ()
+.IR posix_trace_getnext_event ()
+.IR posix_trace_shutdown ()
+.IR posix_trace_start ()
+.IR posix_trace_stop ()
+.IR posix_trace_trygetnext_event ()
+.in
+.fi
+.SS TEF - _POSIX_TRACE_EVENT_FILTER - _SC_TRACE_EVENT_FILTER
+This option implies the
+.B _POSIX_TRACE
+option.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_trace_eventset_add ()
+.IR posix_trace_eventset_del ()
+.IR posix_trace_eventset_empty ()
+.IR posix_trace_eventset_fill ()
+.IR posix_trace_eventset_ismember ()
+.IR posix_trace_get_filter ()
+.IR posix_trace_set_filter ()
+.IR posix_trace_trid_eventid_open ()
+.in
+.fi
+.SS TRI - _POSIX_TRACE_INHERIT - _SC_TRACE_INHERIT
+Tracing children of the traced process is supported.
+This option implies the
+.B _POSIX_TRACE
+option.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_trace_attr_getinherited ()
+.IR posix_trace_attr_setinherited ()
+.in
+.fi
+.SS TRL - _POSIX_TRACE_LOG - _SC_TRACE_LOG
+This option implies the
+.B _POSIX_TRACE
+option.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_trace_attr_getlogfullpolicy ()
+.IR posix_trace_attr_getlogsize ()
+.IR posix_trace_attr_setlogfullpolicy ()
+.IR posix_trace_attr_setlogsize ()
+.IR posix_trace_close ()
+.IR posix_trace_create_withlog ()
+.IR posix_trace_open ()
+.IR posix_trace_rewind ()
+.in
+.fi
+.SS TYM - _POSIX_TYPED_MEMORY_OBJECTS - _SC_TYPED_MEMORY_OBJECT
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR posix_mem_offset ()
+.IR posix_typed_mem_get_info ()
+.IR posix_typed_mem_open ()
+.in
+.fi
+.SS --- - _POSIX_VDISABLE
+Always present (probably 0).
+Value to set a changeable special control
+character to indicate that it is disabled.
+.SH X/OPEN SYSTEM INTERFACE EXTENSIONS
+.SS XSI - _XOPEN_CRYPT - _SC_XOPEN_CRYPT
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR crypt ()
+.IR encrypt ()
+.IR setkey ()
+.fi
+.SS XSI - _XOPEN_REALTIME - _SC_XOPEN_REALTIME
+This option implies the following options:
+.P
+.PD 0
+.TP
+.BR _POSIX_ASYNCHRONOUS_IO == 200112L
+.TP
+.B _POSIX_FSYNC
+.TP
+.B _POSIX_MAPPED_FILES
+.TP
+.BR _POSIX_MEMLOCK == 200112L
+.TP
+.BR _POSIX_MEMLOCK_RANGE == 200112L
+.TP
+.B _POSIX_MEMORY_PROTECTION
+.TP
+.BR _POSIX_MESSAGE_PASSING == 200112L
+.TP
+.B _POSIX_PRIORITIZED_IO
+.TP
+.BR _POSIX_PRIORITY_SCHEDULING == 200112L
+.TP
+.BR _POSIX_REALTIME_SIGNALS == 200112L
+.TP
+.BR _POSIX_SEMAPHORES == 200112L
+.TP
+.BR _POSIX_SHARED_MEMORY_OBJECTS == 200112L
+.TP
+.BR _POSIX_SYNCHRONIZED_IO == 200112L
+.TP
+.BR _POSIX_TIMERS == 200112L
+.PD
+.\"
+.SS ADV - --- - ---
+The Advanced Realtime option group implies that the following options
+are all defined to 200112L:
+.P
+.PD 0
+.TP
+.B _POSIX_ADVISORY_INFO
+.TP
+.B _POSIX_CLOCK_SELECTION
+(implies
+.BR _POSIX_TIMERS )
+.TP
+.B _POSIX_CPUTIME
+(implies
+.BR _POSIX_TIMERS )
+.TP
+.B _POSIX_MONOTONIC_CLOCK
+(implies
+.BR _POSIX_TIMERS )
+.TP
+.B _POSIX_SPAWN
+.TP
+.B _POSIX_SPORADIC_SERVER
+(implies
+.BR _POSIX_PRIORITY_SCHEDULING )
+.TP
+.B _POSIX_TIMEOUTS
+.TP
+.B _POSIX_TYPED_MEMORY_OBJECTS
+.PD
+.\"
+.SS XSI - _XOPEN_REALTIME_THREADS - _SC_XOPEN_REALTIME_THREADS
+This option implies that the following options
+are all defined to 200112L:
+.P
+.PD 0
+.TP
+.B _POSIX_THREAD_PRIO_INHERIT
+.TP
+.B _POSIX_THREAD_PRIO_PROTECT
+.TP
+.B _POSIX_THREAD_PRIORITY_SCHEDULING
+.PD
+.SS ADVANCED REALTIME THREADS - --- - ---
+This option implies that the following options
+are all defined to 200112L:
+.P
+.PD 0
+.TP
+.B _POSIX_BARRIERS
+(implies
+.BR _POSIX_THREADS ,
+.BR _POSIX_THREAD_SAFE_FUNCTIONS )
+.TP
+.B _POSIX_SPIN_LOCKS
+(implies
+.BR _POSIX_THREADS ,
+.BR _POSIX_THREAD_SAFE_FUNCTIONS )
+.TP
+.B _POSIX_THREAD_CPUTIME
+(implies
+.BR _POSIX_TIMERS )
+.TP
+.B _POSIX_THREAD_SPORADIC_SERVER
+(implies
+.BR _POSIX_THREAD_PRIORITY_SCHEDULING )
+.PD
+.\"
+.SS TRACING - --- - ---
+This option implies that the following options
+are all defined to 200112L:
+.P
+.PD 0
+.TP
+.B _POSIX_TRACE
+.TP
+.B _POSIX_TRACE_EVENT_FILTER
+.TP
+.B _POSIX_TRACE_LOG
+.TP
+.B _POSIX_TRACE_INHERIT
+.PD
+.SS STREAMS - _XOPEN_STREAMS - _SC_XOPEN_STREAMS
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR fattach ()
+.IR fdetach ()
+.IR getmsg ()
+.IR getpmsg ()
+.IR ioctl ()
+.IR isastream ()
+.IR putmsg ()
+.IR putpmsg ()
+.in
+.fi
+.SS XSI - _XOPEN_LEGACY - _SC_XOPEN_LEGACY
+Functions included in the legacy option group were previously mandatory,
+but are now optional in this version.
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR bcmp ()
+.IR bcopy ()
+.IR bzero ()
+.IR ecvt ()
+.IR fcvt ()
+.IR ftime ()
+.IR gcvt ()
+.IR getwd ()
+.IR index ()
+.IR mktemp ()
+.IR rindex ()
+.IR utimes ()
+.IR wcswcs ()
+.in
+.fi
+.SS XSI - _XOPEN_UNIX - _SC_XOPEN_UNIX
+The following functions are present:
+.P
+.nf
+.in +4n
+.IR mmap ()
+.IR munmap ()
+.IR msync ()
+.in
+.fi
+.P
+This option implies the following options:
+.P
+.PD 0
+.TP
+.B _POSIX_FSYNC
+.TP
+.B _POSIX_MAPPED_FILES
+.TP
+.B _POSIX_MEMORY_PROTECTION
+.TP
+.B _POSIX_THREAD_ATTR_STACKADDR
+.TP
+.B _POSIX_THREAD_ATTR_STACKSIZE
+.TP
+.B _POSIX_THREAD_PROCESS_SHARED
+.TP
+.B _POSIX_THREAD_SAFE_FUNCTIONS
+.TP
+.B _POSIX_THREADS
+.PD
+.P
+This option may imply the following options from the XSI option groups:
+.P
+.PD 0
+.TP
+.RB "Encryption (" _XOPEN_CRYPT )
+.TP
+.RB "Realtime (" _XOPEN_REALTIME )
+.TP
+.RB "Advanced Realtime (" ADB )
+.TP
+.RB "Realtime Threads (" _XOPEN_REALTIME_THREADS )
+.TP
+.RB "Advanced Realtime Threads (" "ADVANCED REALTIME THREADS" )
+.TP
+.RB "Tracing (" TRACING )
+.TP
+.RB "XSI Streams (" STREAMS )
+.TP
+.RB "Legacy (" _XOPEN_LEGACY )
+.PD
+.SH SEE ALSO
+.BR sysconf (3),
+.BR standards (7)
diff --git a/man/man7/precedence.7 b/man/man7/precedence.7
new file mode 100644
index 000000000..6ef216ddd
--- /dev/null
+++ b/man/man7/precedence.7
@@ -0,0 +1 @@
+.so man7/operator.7
diff --git a/man/man7/process-keyring.7 b/man/man7/process-keyring.7
new file mode 100644
index 000000000..215c72124
--- /dev/null
+++ b/man/man7/process-keyring.7
@@ -0,0 +1,55 @@
+.\" Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH process-keyring 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+process-keyring \- per-process shared keyring
+.SH DESCRIPTION
+The process keyring is a keyring used to anchor keys on behalf of a process.
+It is created only when a process requests it.
+The process keyring has the name (description)
+.IR _pid .
+.P
+A special serial number value,
+.BR KEY_SPEC_PROCESS_KEYRING ,
+is defined that can be used in lieu of the actual serial number of
+the calling process's process keyring.
+.P
+From the
+.BR keyctl (1)
+utility, '\fB@p\fP' can be used instead of a numeric key ID in
+much the same way, but since
+.BR keyctl (1)
+is a program run after forking, this is of no utility.
+.P
+A thread created using the
+.BR clone (2)
+.B CLONE_THREAD
+flag has the same process keyring as the caller of
+.BR clone (2).
+When a new process is created using
+.BR fork ()
+it initially has no process keyring.
+A process's process keyring is cleared on
+.BR execve (2).
+The process keyring is destroyed when the last
+thread that refers to it terminates.
+.P
+If a process doesn't have a process keyring when it is accessed,
+then the process keyring will be created if the keyring is to be modified;
+otherwise, the error
+.B ENOKEY
+results.
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR keyctl (3),
+.BR keyrings (7),
+.BR persistent\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7),
+.BR user\-session\-keyring (7)
diff --git a/man/man7/pthreads.7 b/man/man7/pthreads.7
new file mode 100644
index 000000000..81d0db0e1
--- /dev/null
+++ b/man/man7/pthreads.7
@@ -0,0 +1,937 @@
+.\" Copyright (c) 2005 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthreads 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pthreads \- POSIX threads
+.SH DESCRIPTION
+POSIX.1 specifies a set of interfaces (functions, header files) for
+threaded programming commonly known as POSIX threads, or Pthreads.
+A single process can contain multiple threads,
+all of which are executing the same program.
+These threads share the same global memory (data and heap segments),
+but each thread has its own stack (automatic variables).
+.P
+POSIX.1 also requires that threads share a range of other attributes
+(i.e., these attributes are process-wide rather than per-thread):
+.IP \[bu] 3
+process ID
+.IP \[bu]
+parent process ID
+.IP \[bu]
+process group ID and session ID
+.IP \[bu]
+controlling terminal
+.IP \[bu]
+user and group IDs
+.IP \[bu]
+open file descriptors
+.IP \[bu]
+record locks (see
+.BR fcntl (2))
+.IP \[bu]
+signal dispositions
+.IP \[bu]
+file mode creation mask
+.RB ( umask (2))
+.IP \[bu]
+current directory
+.RB ( chdir (2))
+and
+root directory
+.RB ( chroot (2))
+.IP \[bu]
+interval timers
+.RB ( setitimer (2))
+and POSIX timers
+.RB ( timer_create (2))
+.IP \[bu]
+nice value
+.RB ( setpriority (2))
+.IP \[bu]
+resource limits
+.RB ( setrlimit (2))
+.IP \[bu]
+measurements of the consumption of CPU time
+.RB ( times (2))
+and resources
+.RB ( getrusage (2))
+.P
+As well as the stack, POSIX.1 specifies that various other
+attributes are distinct for each thread, including:
+.IP \[bu] 3
+thread ID (the
+.I pthread_t
+data type)
+.IP \[bu]
+signal mask
+.RB ( pthread_sigmask (3))
+.IP \[bu]
+the
+.I errno
+variable
+.IP \[bu]
+alternate signal stack
+.RB ( sigaltstack (2))
+.IP \[bu]
+real-time scheduling policy and priority
+.RB ( sched (7))
+.P
+The following Linux-specific features are also per-thread:
+.IP \[bu] 3
+capabilities (see
+.BR capabilities (7))
+.IP \[bu]
+CPU affinity
+.RB ( sched_setaffinity (2))
+.SS Pthreads function return values
+Most pthreads functions return 0 on success, and an error number on failure.
+The error numbers that can be returned have the same meaning as
+the error numbers returned in
+.I errno
+by conventional system calls and C library functions.
+Note that the pthreads functions do not set
+.IR errno .
+For each of the pthreads functions that can return an error,
+POSIX.1-2001 specifies that the function can never fail with the error
+.BR EINTR .
+.SS Thread IDs
+Each of the threads in a process has a unique thread identifier
+(stored in the type
+.IR pthread_t ).
+This identifier is returned to the caller of
+.BR pthread_create (3),
+and a thread can obtain its own thread identifier using
+.BR pthread_self (3).
+.P
+Thread IDs are guaranteed to be unique only within a process.
+(In all pthreads functions that accept a thread ID as an argument,
+that ID by definition refers to a thread in
+the same process as the caller.)
+.P
+The system may reuse a thread ID after a terminated thread has been joined,
+or a detached thread has terminated.
+POSIX says: "If an application attempts to use a thread ID whose
+lifetime has ended, the behavior is undefined."
+.SS Thread-safe functions
+A thread-safe function is one that can be safely
+(i.e., it will deliver the same results regardless of whether it is)
+called from multiple threads at the same time.
+.P
+POSIX.1-2001 and POSIX.1-2008 require that all functions specified
+in the standard shall be thread-safe,
+except for the following functions:
+.P
+.in +4n
+.EX
+asctime()
+basename()
+catgets()
+crypt()
+ctermid() if passed a non-NULL argument
+ctime()
+dbm_clearerr()
+dbm_close()
+dbm_delete()
+dbm_error()
+dbm_fetch()
+dbm_firstkey()
+dbm_nextkey()
+dbm_open()
+dbm_store()
+dirname()
+dlerror()
+drand48()
+ecvt() [POSIX.1-2001 only (function removed in POSIX.1-2008)]
+encrypt()
+endgrent()
+endpwent()
+endutxent()
+fcvt() [POSIX.1-2001 only (function removed in POSIX.1-2008)]
+ftw()
+gcvt() [POSIX.1-2001 only (function removed in POSIX.1-2008)]
+getc_unlocked()
+getchar_unlocked()
+getdate()
+getenv()
+getgrent()
+getgrgid()
+getgrnam()
+gethostbyaddr() [POSIX.1-2001 only (function removed in
+                 POSIX.1-2008)]
+gethostbyname() [POSIX.1-2001 only (function removed in
+                 POSIX.1-2008)]
+gethostent()
+getlogin()
+getnetbyaddr()
+getnetbyname()
+getnetent()
+getopt()
+getprotobyname()
+getprotobynumber()
+getprotoent()
+getpwent()
+getpwnam()
+getpwuid()
+getservbyname()
+getservbyport()
+getservent()
+getutxent()
+getutxid()
+getutxline()
+gmtime()
+hcreate()
+hdestroy()
+hsearch()
+inet_ntoa()
+l64a()
+lgamma()
+lgammaf()
+lgammal()
+localeconv()
+localtime()
+lrand48()
+mrand48()
+nftw()
+nl_langinfo()
+ptsname()
+putc_unlocked()
+putchar_unlocked()
+putenv()
+pututxline()
+rand()
+readdir()
+setenv()
+setgrent()
+setkey()
+setpwent()
+setutxent()
+strerror()
+strsignal() [Added in POSIX.1-2008]
+strtok()
+system() [Added in POSIX.1-2008]
+tmpnam() if passed a non-NULL argument
+ttyname()
+unsetenv()
+wcrtomb() if its final argument is NULL
+wcsrtombs() if its final argument is NULL
+wcstombs()
+wctomb()
+.EE
+.in
+.SS Async-cancel-safe functions
+An async-cancel-safe function is one that can be safely called
+in an application where asynchronous cancelability is enabled (see
+.BR pthread_setcancelstate (3)).
+.P
+Only the following functions are required to be async-cancel-safe by
+POSIX.1-2001 and POSIX.1-2008:
+.P
+.in +4n
+.EX
+pthread_cancel()
+pthread_setcancelstate()
+pthread_setcanceltype()
+.EE
+.in
+.SS Cancelation points
+POSIX.1 specifies that certain functions must,
+and certain other functions may, be cancelation points.
+If a thread is cancelable, its cancelability type is deferred,
+and a cancelation request is pending for the thread,
+then the thread is canceled when it calls a function
+that is a cancelation point.
+.P
+The following functions are required to be cancelation points by
+POSIX.1-2001 and/or POSIX.1-2008:
+.P
+.\" FIXME
+.\" Document the list of all functions that are cancelation points in glibc
+.in +4n
+.EX
+accept()
+aio_suspend()
+clock_nanosleep()
+close()
+connect()
+creat()
+fcntl() F_SETLKW
+fdatasync()
+fsync()
+getmsg()
+getpmsg()
+lockf() F_LOCK
+mq_receive()
+mq_send()
+mq_timedreceive()
+mq_timedsend()
+msgrcv()
+msgsnd()
+msync()
+nanosleep()
+open()
+openat() [Added in POSIX.1-2008]
+pause()
+poll()
+pread()
+pselect()
+pthread_cond_timedwait()
+pthread_cond_wait()
+pthread_join()
+pthread_testcancel()
+putmsg()
+putpmsg()
+pwrite()
+read()
+readv()
+recv()
+recvfrom()
+recvmsg()
+select()
+sem_timedwait()
+sem_wait()
+send()
+sendmsg()
+sendto()
+sigpause() [POSIX.1-2001 only (moves to "may" list in POSIX.1-2008)]
+sigsuspend()
+sigtimedwait()
+sigwait()
+sigwaitinfo()
+sleep()
+system()
+tcdrain()
+usleep() [POSIX.1-2001 only (function removed in POSIX.1-2008)]
+wait()
+waitid()
+waitpid()
+write()
+writev()
+.EE
+.in
+.P
+The following functions may be cancelation points according to
+POSIX.1-2001 and/or POSIX.1-2008:
+.P
+.in +4n
+.EX
+access()
+asctime()
+asctime_r()
+catclose()
+catgets()
+catopen()
+chmod() [Added in POSIX.1-2008]
+chown() [Added in POSIX.1-2008]
+closedir()
+closelog()
+ctermid()
+ctime()
+ctime_r()
+dbm_close()
+dbm_delete()
+dbm_fetch()
+dbm_nextkey()
+dbm_open()
+dbm_store()
+dlclose()
+dlopen()
+dprintf() [Added in POSIX.1-2008]
+endgrent()
+endhostent()
+endnetent()
+endprotoent()
+endpwent()
+endservent()
+endutxent()
+faccessat() [Added in POSIX.1-2008]
+fchmod() [Added in POSIX.1-2008]
+fchmodat() [Added in POSIX.1-2008]
+fchown() [Added in POSIX.1-2008]
+fchownat() [Added in POSIX.1-2008]
+fclose()
+fcntl() (for any value of cmd argument)
+fflush()
+fgetc()
+fgetpos()
+fgets()
+fgetwc()
+fgetws()
+fmtmsg()
+fopen()
+fpathconf()
+fprintf()
+fputc()
+fputs()
+fputwc()
+fputws()
+fread()
+freopen()
+fscanf()
+fseek()
+fseeko()
+fsetpos()
+fstat()
+fstatat() [Added in POSIX.1-2008]
+ftell()
+ftello()
+ftw()
+futimens() [Added in POSIX.1-2008]
+fwprintf()
+fwrite()
+fwscanf()
+getaddrinfo()
+getc()
+getc_unlocked()
+getchar()
+getchar_unlocked()
+getcwd()
+getdate()
+getdelim() [Added in POSIX.1-2008]
+getgrent()
+getgrgid()
+getgrgid_r()
+getgrnam()
+getgrnam_r()
+gethostbyaddr() [POSIX.1-2001 only (function removed in
+                 POSIX.1-2008)]
+gethostbyname() [POSIX.1-2001 only (function removed in
+                 POSIX.1-2008)]
+gethostent()
+gethostid()
+gethostname()
+getline() [Added in POSIX.1-2008]
+getlogin()
+getlogin_r()
+getnameinfo()
+getnetbyaddr()
+getnetbyname()
+getnetent()
+getopt() (if opterr is nonzero)
+getprotobyname()
+getprotobynumber()
+getprotoent()
+getpwent()
+getpwnam()
+getpwnam_r()
+getpwuid()
+getpwuid_r()
+gets()
+getservbyname()
+getservbyport()
+getservent()
+getutxent()
+getutxid()
+getutxline()
+getwc()
+getwchar()
+getwd() [POSIX.1-2001 only (function removed in POSIX.1-2008)]
+glob()
+iconv_close()
+iconv_open()
+ioctl()
+link()
+linkat() [Added in POSIX.1-2008]
+lio_listio() [Added in POSIX.1-2008]
+localtime()
+localtime_r()
+lockf() [Added in POSIX.1-2008]
+lseek()
+lstat()
+mkdir() [Added in POSIX.1-2008]
+mkdirat() [Added in POSIX.1-2008]
+mkdtemp() [Added in POSIX.1-2008]
+mkfifo() [Added in POSIX.1-2008]
+mkfifoat() [Added in POSIX.1-2008]
+mknod() [Added in POSIX.1-2008]
+mknodat() [Added in POSIX.1-2008]
+mkstemp()
+mktime()
+nftw()
+opendir()
+openlog()
+pathconf()
+pclose()
+perror()
+popen()
+posix_fadvise()
+posix_fallocate()
+posix_madvise()
+posix_openpt()
+posix_spawn()
+posix_spawnp()
+posix_trace_clear()
+posix_trace_close()
+posix_trace_create()
+posix_trace_create_withlog()
+posix_trace_eventtypelist_getnext_id()
+posix_trace_eventtypelist_rewind()
+posix_trace_flush()
+posix_trace_get_attr()
+posix_trace_get_filter()
+posix_trace_get_status()
+posix_trace_getnext_event()
+posix_trace_open()
+posix_trace_rewind()
+posix_trace_set_filter()
+posix_trace_shutdown()
+posix_trace_timedgetnext_event()
+posix_typed_mem_open()
+printf()
+psiginfo() [Added in POSIX.1-2008]
+psignal() [Added in POSIX.1-2008]
+pthread_rwlock_rdlock()
+pthread_rwlock_timedrdlock()
+pthread_rwlock_timedwrlock()
+pthread_rwlock_wrlock()
+putc()
+putc_unlocked()
+putchar()
+putchar_unlocked()
+puts()
+pututxline()
+putwc()
+putwchar()
+readdir()
+readdir_r()
+readlink() [Added in POSIX.1-2008]
+readlinkat() [Added in POSIX.1-2008]
+remove()
+rename()
+renameat() [Added in POSIX.1-2008]
+rewind()
+rewinddir()
+scandir() [Added in POSIX.1-2008]
+scanf()
+seekdir()
+semop()
+setgrent()
+sethostent()
+setnetent()
+setprotoent()
+setpwent()
+setservent()
+setutxent()
+sigpause() [Added in POSIX.1-2008]
+stat()
+strerror()
+strerror_r()
+strftime()
+symlink()
+symlinkat() [Added in POSIX.1-2008]
+sync()
+syslog()
+tmpfile()
+tmpnam()
+ttyname()
+ttyname_r()
+tzset()
+ungetc()
+ungetwc()
+unlink()
+unlinkat() [Added in POSIX.1-2008]
+utime() [Added in POSIX.1-2008]
+utimensat() [Added in POSIX.1-2008]
+utimes() [Added in POSIX.1-2008]
+vdprintf() [Added in POSIX.1-2008]
+vfprintf()
+vfwprintf()
+vprintf()
+vwprintf()
+wcsftime()
+wordexp()
+wprintf()
+wscanf()
+.EE
+.in
+.P
+An implementation may also mark other functions
+not specified in the standard as cancelation points.
+In particular, an implementation is likely to mark
+any nonstandard function that may block as a cancelation point.
+(This includes most functions that can touch files.)
+.P
+It should be noted that even if an application is not using
+asynchronous cancelation, that calling a function from the above list
+from an asynchronous signal handler may cause the equivalent of
+asynchronous cancelation.
+The underlying user code may not expect
+asynchronous cancelation and the state of the user data may become
+inconsistent.
+Therefore signals should be used with caution when
+entering a region of deferred cancelation.
+.\" So, scanning "cancelation point" comments in the glibc 2.8 header
+.\" files, it looks as though at least the following nonstandard
+.\" functions are cancelation points:
+.\" endnetgrent
+.\" endspent
+.\" epoll_pwait
+.\" epoll_wait
+.\" fcloseall
+.\" fdopendir
+.\" fflush_unlocked
+.\" fgetc_unlocked
+.\" fgetgrent
+.\" fgetgrent_r
+.\" fgetpwent
+.\" fgetpwent_r
+.\" fgets_unlocked
+.\" fgetspent
+.\" fgetspent_r
+.\" fgetwc_unlocked
+.\" fgetws_unlocked
+.\" fputc_unlocked
+.\" fputs_unlocked
+.\" fputwc_unlocked
+.\" fputws_unlocked
+.\" fread_unlocked
+.\" fwrite_unlocked
+.\" gai_suspend
+.\" getaddrinfo_a
+.\" getdate_r
+.\" getgrent_r
+.\" getgrouplist
+.\" gethostbyaddr_r
+.\" gethostbyname2
+.\" gethostbyname2_r
+.\" gethostbyname_r
+.\" gethostent_r
+.\" getnetbyaddr_r
+.\" getnetbyname_r
+.\" getnetent_r
+.\" getnetgrent
+.\" getnetgrent_r
+.\" getprotobyname_r
+.\" getprotobynumber_r
+.\" getprotoent_r
+.\" getpw
+.\" getpwent_r
+.\" getservbyname_r
+.\" getservbyport_r
+.\" getservent_r
+.\" getspent
+.\" getspent_r
+.\" getspnam
+.\" getspnam_r
+.\" getutmp
+.\" getutmpx
+.\" getw
+.\" getwc_unlocked
+.\" getwchar_unlocked
+.\" initgroups
+.\" innetgr
+.\" mkostemp
+.\" mkostemp64
+.\" mkstemp64
+.\" ppoll
+.\" pthread_timedjoin_np
+.\" putgrent
+.\" putpwent
+.\" putspent
+.\" putw
+.\" putwc_unlocked
+.\" putwchar_unlocked
+.\" rcmd
+.\" rcmd_af
+.\" rexec
+.\" rexec_af
+.\" rresvport
+.\" rresvport_af
+.\" ruserok
+.\" ruserok_af
+.\" setnetgrent
+.\" setspent
+.\" sgetspent
+.\" sgetspent_r
+.\" updwtmpx
+.\" utmpxname
+.\" vfscanf
+.\" vfwscanf
+.\" vscanf
+.\" vsyslog
+.\" vwscanf
+.SS Compiling on Linux
+On Linux, programs that use the Pthreads API should be compiled using
+.IR "cc \-pthread" .
+.SS Linux implementations of POSIX threads
+Over time, two threading implementations have been provided by
+the GNU C library on Linux:
+.TP
+.B LinuxThreads
+This is the original Pthreads implementation.
+Since glibc 2.4, this implementation is no longer supported.
+.TP
+.BR NPTL " (Native POSIX Threads Library)"
+This is the modern Pthreads implementation.
+By comparison with LinuxThreads, NPTL provides closer conformance to
+the requirements of the POSIX.1 specification and better performance
+when creating large numbers of threads.
+NPTL is available since glibc 2.3.2,
+and requires features that are present in the Linux 2.6 kernel.
+.P
+Both of these are so-called 1:1 implementations, meaning that each
+thread maps to a kernel scheduling entity.
+Both threading implementations employ the Linux
+.BR clone (2)
+system call.
+In NPTL, thread synchronization primitives (mutexes,
+thread joining, and so on) are implemented using the Linux
+.BR futex (2)
+system call.
+.SS LinuxThreads
+The notable features of this implementation are the following:
+.IP \[bu] 3
+In addition to the main (initial) thread,
+and the threads that the program creates using
+.BR pthread_create (3),
+the implementation creates a "manager" thread.
+This thread handles thread creation and termination.
+(Problems can result if this thread is inadvertently killed.)
+.IP \[bu]
+Signals are used internally by the implementation.
+On Linux 2.2 and later, the first three real-time signals are used
+(see also
+.BR signal (7)).
+On older Linux kernels,
+.B SIGUSR1
+and
+.B SIGUSR2
+are used.
+Applications must avoid the use of whichever set of signals is
+employed by the implementation.
+.IP \[bu]
+Threads do not share process IDs.
+(In effect, LinuxThreads threads are implemented as processes which share
+more information than usual, but which do not share a common process ID.)
+LinuxThreads threads (including the manager thread)
+are visible as separate processes using
+.BR ps (1).
+.P
+The LinuxThreads implementation deviates from the POSIX.1
+specification in a number of ways, including the following:
+.IP \[bu] 3
+Calls to
+.BR getpid (2)
+return a different value in each thread.
+.IP \[bu]
+Calls to
+.BR getppid (2)
+in threads other than the main thread return the process ID of the
+manager thread; instead
+.BR getppid (2)
+in these threads should return the same value as
+.BR getppid (2)
+in the main thread.
+.IP \[bu]
+When one thread creates a new child process using
+.BR fork (2),
+any thread should be able to
+.BR wait (2)
+on the child.
+However, the implementation allows only the thread that
+created the child to
+.BR wait (2)
+on it.
+.IP \[bu]
+When a thread calls
+.BR execve (2),
+all other threads are terminated (as required by POSIX.1).
+However, the resulting process has the same PID as the thread that called
+.BR execve (2):
+it should have the same PID as the main thread.
+.IP \[bu]
+Threads do not share user and group IDs.
+This can cause complications with set-user-ID programs and
+can cause failures in Pthreads functions if an application
+changes its credentials using
+.BR seteuid (2)
+or similar.
+.IP \[bu]
+Threads do not share a common session ID and process group ID.
+.IP \[bu]
+Threads do not share record locks created using
+.BR fcntl (2).
+.IP \[bu]
+The information returned by
+.BR times (2)
+and
+.BR getrusage (2)
+is per-thread rather than process-wide.
+.IP \[bu]
+Threads do not share semaphore undo values (see
+.BR semop (2)).
+.IP \[bu]
+Threads do not share interval timers.
+.IP \[bu]
+Threads do not share a common nice value.
+.IP \[bu]
+POSIX.1 distinguishes the notions of signals that are directed
+to the process as a whole and signals that are directed to individual
+threads.
+According to POSIX.1, a process-directed signal (sent using
+.BR kill (2),
+for example) should be handled by a single,
+arbitrarily selected thread within the process.
+LinuxThreads does not support the notion of process-directed signals:
+signals may be sent only to specific threads.
+.IP \[bu]
+Threads have distinct alternate signal stack settings.
+However, a new thread's alternate signal stack settings
+are copied from the thread that created it, so that
+the threads initially share an alternate signal stack.
+(A new thread should start with no alternate signal stack defined.
+If two threads handle signals on their shared alternate signal
+stack at the same time, unpredictable program failures are
+likely to occur.)
+.SS NPTL
+With NPTL, all of the threads in a process are placed
+in the same thread group;
+all members of a thread group share the same PID.
+NPTL does not employ a manager thread.
+.P
+NPTL makes internal use of the first two real-time signals;
+these signals cannot be used in applications.
+See
+.BR nptl (7)
+for further details.
+.P
+NPTL still has at least one nonconformance with POSIX.1:
+.IP \[bu] 3
+Threads do not share a common nice value.
+.\" FIXME . bug report filed for NPTL nice nonconformance
+.\" http://bugzilla.kernel.org/show_bug.cgi?id=6258
+.\" Sep 08: there is a patch by Denys Vlasenko to address this
+.\" "make setpriority POSIX compliant; introduce PRIO_THREAD extension"
+.\" Monitor this to see if it makes it into mainline.
+.P
+Some NPTL nonconformances occur only with older kernels:
+.IP \[bu] 3
+The information returned by
+.BR times (2)
+and
+.BR getrusage (2)
+is per-thread rather than process-wide (fixed in Linux 2.6.9).
+.IP \[bu]
+Threads do not share resource limits (fixed in Linux 2.6.10).
+.IP \[bu]
+Threads do not share interval timers (fixed in Linux 2.6.12).
+.IP \[bu]
+Only the main thread is permitted to start a new session using
+.BR setsid (2)
+(fixed in Linux 2.6.16).
+.IP \[bu]
+Only the main thread is permitted to make the process into a
+process group leader using
+.BR setpgid (2)
+(fixed in Linux 2.6.16).
+.IP \[bu]
+Threads have distinct alternate signal stack settings.
+However, a new thread's alternate signal stack settings
+are copied from the thread that created it, so that
+the threads initially share an alternate signal stack
+(fixed in Linux 2.6.16).
+.P
+Note the following further points about the NPTL implementation:
+.IP \[bu] 3
+If the stack size soft resource limit (see the description of
+.B RLIMIT_STACK
+in
+.BR setrlimit (2))
+is set to a value other than
+.IR unlimited ,
+then this value defines the default stack size for new threads.
+To be effective, this limit must be set before the program
+is executed, perhaps using the
+.I ulimit \-s
+shell built-in command
+.RI ( "limit stacksize"
+in the C shell).
+.SS Determining the threading implementation
+Since glibc 2.3.2, the
+.BR getconf (1)
+command can be used to determine
+the system's threading implementation, for example:
+.P
+.in +4n
+.EX
+bash$ getconf GNU_LIBPTHREAD_VERSION
+NPTL 2.3.4
+.EE
+.in
+.P
+With older glibc versions, a command such as the following should
+be sufficient to determine the default threading implementation:
+.P
+.in +4n
+.EX
+bash$ $( ldd /bin/ls | grep libc.so | awk \[aq]{print $3}\[aq] ) | \e
+                egrep \-i \[aq]threads|nptl\[aq]
+        Native POSIX Threads Library by Ulrich Drepper et al
+.EE
+.in
+.SS Selecting the threading implementation: LD_ASSUME_KERNEL
+On systems with a glibc that supports both LinuxThreads and NPTL
+(i.e., glibc 2.3.\fIx\fP), the
+.B LD_ASSUME_KERNEL
+environment variable can be used to override
+the dynamic linker's default choice of threading implementation.
+This variable tells the dynamic linker to assume that it is
+running on top of a particular kernel version.
+By specifying a kernel version that does not
+provide the support required by NPTL, we can force the use
+of LinuxThreads.
+(The most likely reason for doing this is to run a
+(broken) application that depends on some nonconformant behavior
+in LinuxThreads.)
+For example:
+.P
+.in +4n
+.EX
+bash$ $( LD_ASSUME_KERNEL=2.2.5 ldd /bin/ls | grep libc.so | \e
+                awk \[aq]{print $3}\[aq] ) | egrep \-i \[aq]threads|nptl\[aq]
+        linuxthreads\-0.10 by Xavier Leroy
+.EE
+.in
+.SH SEE ALSO
+.ad l
+.nh
+.BR clone (2),
+.BR fork (2),
+.BR futex (2),
+.BR gettid (2),
+.BR proc (5),
+.BR attributes (7),
+.BR futex (7),
+.BR nptl (7),
+.BR sigevent (3type),
+.BR signal (7)
+.P
+Various Pthreads manual pages, for example:
+.BR pthread_atfork (3),
+.BR pthread_attr_init (3),
+.BR pthread_cancel (3),
+.BR pthread_cleanup_push (3),
+.BR pthread_cond_signal (3),
+.BR pthread_cond_wait (3),
+.BR pthread_create (3),
+.BR pthread_detach (3),
+.BR pthread_equal (3),
+.BR pthread_exit (3),
+.BR pthread_key_create (3),
+.BR pthread_kill (3),
+.BR pthread_mutex_lock (3),
+.BR pthread_mutex_unlock (3),
+.BR pthread_mutexattr_destroy (3),
+.BR pthread_mutexattr_init (3),
+.BR pthread_once (3),
+.BR pthread_spin_init (3),
+.BR pthread_spin_lock (3),
+.BR pthread_rwlockattr_setkind_np (3),
+.BR pthread_setcancelstate (3),
+.BR pthread_setcanceltype (3),
+.BR pthread_setspecific (3),
+.BR pthread_sigmask (3),
+.BR pthread_sigqueue (3),
+and
+.BR pthread_testcancel (3)
diff --git a/man/man7/pty.7 b/man/man7/pty.7
new file mode 100644
index 000000000..7f47ce550
--- /dev/null
+++ b/man/man7/pty.7
@@ -0,0 +1,161 @@
+.\" Copyright (C) 2005 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pty 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+pty \- pseudoterminal interfaces
+.SH DESCRIPTION
+A pseudoterminal (sometimes abbreviated "pty")
+is a pair of virtual character devices that
+provide a bidirectional communication channel.
+One end of the channel is called the
+.IR master ;
+the other end is called the
+.IR slave .
+.P
+The slave end of the pseudoterminal provides an interface
+that behaves exactly like a classical terminal.
+A process that expects to be connected to a terminal,
+can open the slave end of a pseudoterminal and
+then be driven by a program that has opened the master end.
+Anything that is written on the master end is provided to the process
+on the slave end as though it was input typed on a terminal.
+For example, writing the interrupt character (usually control-C)
+to the master device would cause an interrupt signal
+.RB ( SIGINT )
+to be generated for the foreground process group
+that is connected to the slave.
+Conversely, anything that is written to the slave end of the
+pseudoterminal can be read by the process that is connected to
+the master end.
+.P
+Data flow between master and slave is handled asynchronously,
+much like data flow with a physical terminal.
+Data written to the slave will be available at the master promptly,
+but may not be available immediately.
+Similarly, there may be a small processing delay between
+a write to the master, and the effect being visible at the slave.
+.P
+Historically, two pseudoterminal APIs have evolved: BSD and System V.
+SUSv1 standardized a pseudoterminal API based on the System V API,
+and this API should be employed in all new programs that use
+pseudoterminals.
+.P
+Linux provides both BSD-style and (standardized) System V-style
+pseudoterminals.
+System V-style terminals are commonly called UNIX 98 pseudoterminals
+on Linux systems.
+.P
+Since Linux 2.6.4, BSD-style pseudoterminals are considered deprecated:
+support can be disabled when building the kernel by disabling the
+.B CONFIG_LEGACY_PTYS
+option.
+(Starting with Linux 2.6.30,
+that option is disabled by default in the mainline kernel.)
+UNIX 98 pseudoterminals should be used in new applications.
+.SS UNIX 98 pseudoterminals
+An unused UNIX 98 pseudoterminal master is opened by calling
+.BR posix_openpt (3).
+(This function opens the master clone device,
+.IR /dev/ptmx ;
+see
+.BR pts (4).)
+After performing any program-specific initializations,
+changing the ownership and permissions of the slave device using
+.BR grantpt (3),
+and unlocking the slave using
+.BR unlockpt (3)),
+the corresponding slave device can be opened by passing
+the name returned by
+.BR ptsname (3)
+in a call to
+.BR open (2).
+.P
+The Linux kernel imposes a limit on the number of available
+UNIX 98 pseudoterminals.
+Up to and including Linux 2.6.3, this limit is configured
+at kernel compilation time
+.RB ( CONFIG_UNIX98_PTYS ),
+and the permitted number of pseudoterminals can be up to 2048,
+with a default setting of 256.
+Since Linux 2.6.4, the limit is dynamically adjustable via
+.IR /proc/sys/kernel/pty/max ,
+and a corresponding file,
+.IR /proc/sys/kernel/pty/nr ,
+indicates how many pseudoterminals are currently in use.
+For further details on these two files, see
+.BR proc (5).
+.SS BSD pseudoterminals
+BSD-style pseudoterminals are provided as precreated pairs, with
+names of the form
+.I /dev/ptyXY
+(master) and
+.I /dev/ttyXY
+(slave),
+where X is a letter from the 16-character set [p\-za\-e],
+and Y is a letter from the 16-character set [0\-9a\-f].
+(The precise range of letters in these two sets varies across UNIX
+implementations.)
+For example,
+.I /dev/ptyp1
+and
+.I /dev/ttyp1
+constitute a BSD pseudoterminal pair.
+A process finds an unused pseudoterminal pair by trying to
+.BR open (2)
+each pseudoterminal master until an open succeeds.
+The corresponding pseudoterminal slave (substitute "tty"
+for "pty" in the name of the master) can then be opened.
+.SH FILES
+.TP
+.I /dev/ptmx
+UNIX 98 master clone device
+.TP
+.I /dev/pts/*
+UNIX 98 slave devices
+.TP
+.I /dev/pty[p\-za\-e][0\-9a\-f]
+BSD master devices
+.TP
+.I /dev/tty[p\-za\-e][0\-9a\-f]
+BSD slave devices
+.SH NOTES
+Pseudoterminals are used by applications such as network login services
+(\c
+.BR ssh (1),
+.BR rlogin (1),
+.BR telnet (1)),
+terminal emulators such as
+.BR xterm (1),
+.BR script (1),
+.BR screen (1),
+.BR tmux (1),
+.BR unbuffer (1),
+and
+.BR expect (1).
+.P
+A description of the
+.B TIOCPKT
+.BR ioctl (2),
+which controls packet mode operation, can be found in
+.BR ioctl_tty (2).
+.P
+The BSD
+.BR ioctl (2)
+operations
+.BR TIOCSTOP ,
+.BR TIOCSTART ,
+.BR TIOCUCNTL ,
+and
+.B TIOCREMOTE
+have not been implemented under Linux.
+.SH SEE ALSO
+.BR ioctl_tty (2),
+.BR select (2),
+.BR setsid (2),
+.BR forkpty (3),
+.BR openpty (3),
+.BR termios (3),
+.BR pts (4),
+.BR tty (4)
diff --git a/man/man7/queue.7 b/man/man7/queue.7
new file mode 100644
index 000000000..2b58cb43a
--- /dev/null
+++ b/man/man7/queue.7
@@ -0,0 +1,138 @@
+.\" Copyright (c) 1993
+.\"    The Regents of the University of California.  All rights reserved.
+.\" and Copyright (c) 2020 by Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"
+.TH queue 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+queue \- implementations of linked lists and queues
+.SH DESCRIPTION
+The
+.I <sys/queue.h>
+header file provides a set of macros that
+define and operate on the following data structures:
+.TP
+SLIST
+singly linked lists
+.TP
+LIST
+doubly linked lists
+.TP
+STAILQ
+singly linked tail queues
+.TP
+TAILQ
+doubly linked tail queues
+.TP
+CIRCLEQ
+doubly linked circular queues
+.P
+All structures support the following functionality:
+.IP \[bu] 3
+Insertion of a new entry at the head of the list.
+.IP \[bu]
+Insertion of a new entry after any element in the list.
+.IP \[bu]
+O(1) removal of an entry from the head of the list.
+.IP \[bu]
+Forward traversal through the list.
+.\".IP \[bu]
+.\" Swapping the contents of two lists.
+.P
+Code size and execution time
+depend on the complexity of the data structure being used,
+so programmers should take care to choose the appropriate one.
+.SS Singly linked lists (SLIST)
+Singly linked lists are the simplest
+and support only the above functionality.
+Singly linked lists are ideal for applications with
+large datasets and few or no removals,
+or for implementing a LIFO queue.
+Singly linked lists add the following functionality:
+.IP \[bu] 3
+O(n) removal of any entry in the list.
+.SS Singly linked tail queues (STAILQ)
+Singly linked tail queues add the following functionality:
+.IP \[bu] 3
+Entries can be added at the end of a list.
+.IP \[bu]
+O(n) removal of any entry in the list.
+.IP \[bu]
+They may be concatenated.
+.P
+However:
+.IP \[bu] 3
+All list insertions must specify the head of the list.
+.IP \[bu]
+Each head entry requires two pointers rather than one.
+.P
+Singly linked tail queues are ideal for applications with
+large datasets and few or no removals,
+or for implementing a FIFO queue.
+.SS Doubly linked data structures
+All doubly linked types of data structures (lists and tail queues)
+additionally allow:
+.IP \[bu] 3
+Insertion of a new entry before any element in the list.
+.IP \[bu]
+O(1) removal of any entry in the list.
+.P
+However:
+.IP \[bu] 3
+Each element requires two pointers rather than one.
+.SS Doubly linked lists (LIST)
+Linked lists are the simplest of the doubly linked data structures.
+They add the following functionality over the above:
+.IP \[bu] 3
+They may be traversed backwards.
+.P
+However:
+.IP \[bu] 3
+To traverse backwards, an entry to begin the traversal and the list in
+which it is contained must be specified.
+.SS Doubly linked tail queues (TAILQ)
+Tail queues add the following functionality:
+.IP \[bu] 3
+Entries can be added at the end of a list.
+.IP \[bu]
+They may be traversed backwards, from tail to head.
+.IP \[bu]
+They may be concatenated.
+.P
+However:
+.IP \[bu] 3
+All list insertions and removals must specify the head of the list.
+.IP \[bu]
+Each head entry requires two pointers rather than one.
+.SS Doubly linked circular queues (CIRCLEQ)
+Circular queues add the following functionality over the above:
+.IP \[bu] 3
+The first and last entries are connected.
+.P
+However:
+.IP \[bu] 3
+The termination condition for traversal is more complex.
+.SH STANDARDS
+BSD.
+.SH HISTORY
+.I <sys/queue.h>
+macros first appeared in 4.4BSD.
+.SH NOTES
+Some BSDs provide SIMPLEQ instead of STAILQ.
+They are identical, but for historical reasons
+they were named differently on different BSDs.
+STAILQ originated on FreeBSD, and SIMPLEQ originated on NetBSD.
+For compatibility reasons, some systems provide both sets of macros.
+glibc provides both STAILQ and SIMPLEQ,
+which are identical except for a missing SIMPLEQ equivalent to
+.BR STAILQ_CONCAT ().
+.SH SEE ALSO
+.BR circleq (3),
+.BR insque (3),
+.BR list (3),
+.BR slist (3),
+.BR stailq (3),
+.BR tailq (3)
+.\" .BR tree (3)
diff --git a/man/man7/random.7 b/man/man7/random.7
new file mode 100644
index 000000000..5062b1900
--- /dev/null
+++ b/man/man7/random.7
@@ -0,0 +1,213 @@
+'\" t
+.\" Copyright (C) 2008, George Spelvin <linux@horizon.com>,
+.\" and Copyright (C) 2008, Matt Mackall <mpm@selenic.com>
+.\" and Copyright (C) 2016, Laurent Georget <laurent.georget@supelec.fr>
+.\" and Copyright (C) 2016, Nikos Mavrogiannopoulos <nmav@redhat.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" The following web page is quite informative:
+.\" http://www.2uo.de/myths-about-urandom/
+.\"
+.TH random 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+random \- overview of interfaces for obtaining randomness
+.SH DESCRIPTION
+The kernel random-number generator relies on entropy gathered from
+device drivers and other sources of environmental noise to seed
+a cryptographically secure pseudorandom number generator (CSPRNG).
+It is designed for security, rather than speed.
+.P
+The following interfaces provide access to output from the kernel CSPRNG:
+.IP \[bu] 3
+The
+.I /dev/urandom
+and
+.I /dev/random
+devices, both described in
+.BR random (4).
+These devices have been present on Linux since early times,
+and are also available on many other systems.
+.IP \[bu]
+The Linux-specific
+.BR getrandom (2)
+system call, available since Linux 3.17.
+This system call provides access either to the same source as
+.I /dev/urandom
+(called the
+.I urandom
+source in this page)
+or to the same source as
+.I /dev/random
+(called the
+.I random
+source in this page).
+The default is the
+.I urandom
+source; the
+.I random
+source is selected by specifying the
+.B GRND_RANDOM
+flag to the system call.
+(The
+.BR getentropy (3)
+function provides a slightly more portable interface on top of
+.BR getrandom (2).)
+.\"
+.SS Initialization of the entropy pool
+The kernel collects bits of entropy from the environment.
+When a sufficient number of random bits has been collected, the
+entropy pool is considered to be initialized.
+.SS Choice of random source
+Unless you are doing long-term key generation (and most likely not even
+then), you probably shouldn't be reading from the
+.I /dev/random
+device or employing
+.BR getrandom (2)
+with the
+.B GRND_RANDOM
+flag.
+Instead, either read from the
+.I /dev/urandom
+device or employ
+.BR getrandom (2)
+without the
+.B GRND_RANDOM
+flag.
+The cryptographic algorithms used for the
+.I urandom
+source are quite conservative, and so should be sufficient for all purposes.
+.P
+The disadvantage of
+.B GRND_RANDOM
+and reads from
+.I /dev/random
+is that the operation can block for an indefinite period of time.
+Furthermore, dealing with the partially fulfilled
+requests that can occur when using
+.B GRND_RANDOM
+or when reading from
+.I /dev/random
+increases code complexity.
+.\"
+.SS Monte Carlo and other probabilistic sampling applications
+Using these interfaces to provide large quantities of data for
+Monte Carlo simulations or other programs/algorithms which are
+doing probabilistic sampling will be slow.
+Furthermore, it is unnecessary, because such applications do not
+need cryptographically secure random numbers.
+Instead, use the interfaces described in this page to obtain
+a small amount of data to seed a user-space pseudorandom
+number generator for use by such applications.
+.\"
+.SS Comparison between getrandom, /dev/urandom, and /dev/random
+The following table summarizes the behavior of the various
+interfaces that can be used to obtain randomness.
+.B GRND_NONBLOCK
+is a flag that can be used to control the blocking behavior of
+.BR getrandom (2).
+The final column of the table considers the case that can occur
+in early boot time when the entropy pool is not yet initialized.
+.ad l
+.TS
+allbox;
+lbw13 lbw12 lbw14 lbw18
+l l l l.
+Interface	Pool	T{
+Blocking
+\%behavior
+T}	T{
+Behavior when pool is not yet ready
+T}
+T{
+.I /dev/random
+T}	T{
+Blocking pool
+T}	T{
+If entropy too low, blocks until there is enough entropy again
+T}	T{
+Blocks until enough entropy gathered
+T}
+T{
+.I /dev/urandom
+T}	T{
+CSPRNG output
+T}	T{
+Never blocks
+T}	T{
+Returns output from uninitialized CSPRNG (may be low entropy and unsuitable for cryptography)
+T}
+T{
+.BR getrandom ()
+T}	T{
+Same as
+.I /dev/urandom
+T}	T{
+Does not block once is pool ready
+T}	T{
+Blocks until pool ready
+T}
+T{
+.BR getrandom ()
+.B GRND_RANDOM
+T}	T{
+Same as
+.I /dev/random
+T}	T{
+If entropy too low, blocks until there is enough entropy again
+T}	T{
+Blocks until pool ready
+T}
+T{
+.BR getrandom ()
+.B GRND_NONBLOCK
+T}	T{
+Same as
+.I /dev/urandom
+T}	T{
+Does not block once is pool ready
+T}	T{
+.B EAGAIN
+T}
+T{
+.BR getrandom ()
+.B GRND_RANDOM
++
+.B GRND_NONBLOCK
+T}	T{
+Same as
+.I /dev/random
+T}	T{
+.B EAGAIN
+if not enough entropy available
+T}	T{
+.B EAGAIN
+T}
+.TE
+.ad
+.\"
+.SS Generating cryptographic keys
+The amount of seed material required to generate a cryptographic key
+equals the effective key size of the key.
+For example, a 3072-bit RSA
+or Diffie-Hellman private key has an effective key size of 128 bits
+(it requires about 2\[ha]128 operations to break) so a key generator
+needs only 128 bits (16 bytes) of seed material from
+.IR /dev/random .
+.P
+While some safety margin above that minimum is reasonable, as a guard
+against flaws in the CSPRNG algorithm, no cryptographic primitive
+available today can hope to promise more than 256 bits of security,
+so if any program reads more than 256 bits (32 bytes) from the kernel
+random pool per invocation, or per reasonable reseed interval (not less
+than one minute), that should be taken as a sign that its cryptography is
+.I not
+skillfully implemented.
+.\"
+.SH SEE ALSO
+.BR getrandom (2),
+.BR getauxval (3),
+.BR getentropy (3),
+.BR random (4),
+.BR urandom (4),
+.BR signal (7)
diff --git a/man/man7/raw.7 b/man/man7/raw.7
new file mode 100644
index 000000000..12ccd8fdf
--- /dev/null
+++ b/man/man7/raw.7
@@ -0,0 +1,281 @@
+'\" t
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: raw.7,v 1.6 1999/06/05 10:32:08 freitag Exp $
+.\"
+.TH raw 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+raw \- Linux IPv4 raw sockets
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <netinet/in.h>
+.BI "raw_socket = socket(AF_INET, SOCK_RAW, int " protocol );
+.fi
+.SH DESCRIPTION
+Raw sockets allow new IPv4 protocols to be implemented in user space.
+A raw socket receives or sends the raw datagram not
+including link level headers.
+.P
+The IPv4 layer generates an IP header when sending a packet unless the
+.B IP_HDRINCL
+socket option is enabled on the socket.
+When it is enabled, the packet must contain an IP header.
+For receiving, the IP header is always included in the packet.
+.P
+In order to create a raw socket, a process must have the
+.B CAP_NET_RAW
+capability in the user namespace that governs its network namespace.
+.P
+All packets or errors matching the
+.I protocol
+number specified
+for the raw socket are passed to this socket.
+For a list of the allowed protocols,
+see the IANA list of assigned protocol numbers at
+.UR http://www.iana.org/assignments/protocol\-numbers/
+.UE
+and
+.BR getprotobyname (3).
+.P
+A protocol of
+.B IPPROTO_RAW
+implies enabled
+.B IP_HDRINCL
+and is able to send any IP protocol that is specified in the passed
+header.
+Receiving of all IP protocols via
+.B IPPROTO_RAW
+is not possible using raw sockets.
+.RS
+.TS
+tab(:) allbox;
+c s
+l l.
+IP Header fields modified on sending by \fBIP_HDRINCL\fP
+IP Checksum:Always filled in
+Source Address:Filled in when zero
+Packet ID:Filled in when zero
+Total Length:Always filled in
+.TE
+.RE
+.P
+If
+.B IP_HDRINCL
+is specified and the IP header has a nonzero destination address, then
+the destination address of the socket is used to route the packet.
+When
+.B MSG_DONTROUTE
+is specified, the destination address should refer to a local interface,
+otherwise a routing table lookup is done anyway but gatewayed routes
+are ignored.
+.P
+If
+.B IP_HDRINCL
+isn't set, then IP header options can be set on raw sockets with
+.BR setsockopt (2);
+see
+.BR ip (7)
+for more information.
+.P
+Starting with Linux 2.2, all IP header fields and options can be set using
+IP socket options.
+This means raw sockets are usually needed only for new
+protocols or protocols with no user interface (like ICMP).
+.P
+When a packet is received, it is passed to any raw sockets which have
+been bound to its protocol before it is passed to other protocol handlers
+(e.g., kernel protocol modules).
+.SS Address format
+For sending and receiving datagrams
+.RB ( sendto (2),
+.BR recvfrom (2),
+and similar),
+raw sockets use the standard
+.I sockaddr_in
+address structure defined in
+.BR ip (7).
+The
+.I sin_port
+field could be used to specify the IP protocol number,
+but it is ignored for sending in Linux 2.2 and later, and should be always
+set to 0 (see BUGS).
+For incoming packets,
+.I sin_port
+.\" commit f59fc7f30b710d45aadf715460b3e60dbe9d3418
+is set to zero.
+.SS Socket options
+Raw socket options can be set with
+.BR setsockopt (2)
+and read with
+.BR getsockopt (2)
+by passing the
+.B IPPROTO_RAW
+.\" Or SOL_RAW on Linux
+family flag.
+.TP
+.B ICMP_FILTER
+Enable a special filter for raw sockets bound to the
+.B IPPROTO_ICMP
+protocol.
+The value has a bit set for each ICMP message type which
+should be filtered out.
+The default is to filter no ICMP messages.
+.P
+In addition, all
+.BR ip (7)
+.B IPPROTO_IP
+socket options valid for datagram sockets are supported.
+.SS Error handling
+Errors originating from the network are passed to the user only when the
+socket is connected or the
+.B IP_RECVERR
+flag is enabled.
+For connected sockets, only
+.B EMSGSIZE
+and
+.B EPROTO
+are passed for compatibility.
+With
+.BR IP_RECVERR ,
+all network errors are saved in the error queue.
+.SH ERRORS
+.TP
+.B EACCES
+User tried to send to a broadcast address without having the
+broadcast flag set on the socket.
+.TP
+.B EFAULT
+An invalid memory address was supplied.
+.TP
+.B EINVAL
+Invalid argument.
+.TP
+.B EMSGSIZE
+Packet too big.
+Either Path MTU Discovery is enabled (the
+.B IP_MTU_DISCOVER
+socket flag) or the packet size exceeds the maximum allowed IPv4
+packet size of 64\ kB.
+.TP
+.B EOPNOTSUPP
+Invalid flag has been passed to a socket call (like
+.BR MSG_OOB ).
+.TP
+.B EPERM
+The user doesn't have permission to open raw sockets.
+Only processes with an effective user ID of 0 or the
+.B CAP_NET_RAW
+attribute may do that.
+.TP
+.B EPROTO
+An ICMP error has arrived reporting a parameter problem.
+.SH VERSIONS
+.B IP_RECVERR
+and
+.B ICMP_FILTER
+are new in Linux 2.2.
+They are Linux extensions and should not be used in portable programs.
+.P
+Linux 2.0 enabled some bug-to-bug compatibility with BSD in the
+raw socket code when the
+.B SO_BSDCOMPAT
+socket option was set; since Linux 2.2,
+this option no longer has that effect.
+.SH NOTES
+By default, raw sockets do path MTU (Maximum Transmission Unit) discovery.
+This means the kernel
+will keep track of the MTU to a specific target IP address and return
+.B EMSGSIZE
+when a raw packet write exceeds it.
+When this happens, the application should decrease the packet size.
+Path MTU discovery can be also turned off using the
+.B IP_MTU_DISCOVER
+socket option or the
+.I /proc/sys/net/ipv4/ip_no_pmtu_disc
+file, see
+.BR ip (7)
+for details.
+When turned off, raw sockets will fragment outgoing packets
+that exceed the interface MTU.
+However, disabling it is not recommended
+for performance and reliability reasons.
+.P
+A raw socket can be bound to a specific local address using the
+.BR bind (2)
+call.
+If it isn't bound, all packets with the specified IP protocol are received.
+In addition, a raw socket can be bound to a specific network device using
+.BR SO_BINDTODEVICE ;
+see
+.BR socket (7).
+.P
+An
+.B IPPROTO_RAW
+socket is send only.
+If you really want to receive all IP packets, use a
+.BR packet (7)
+socket with the
+.B ETH_P_IP
+protocol.
+Note that packet sockets don't reassemble IP fragments,
+unlike raw sockets.
+.P
+If you want to receive all ICMP packets for a datagram socket,
+it is often better to use
+.B IP_RECVERR
+on that particular socket; see
+.BR ip (7).
+.P
+Raw sockets may tap all IP protocols in Linux, even
+protocols like ICMP or TCP which have a protocol module in the kernel.
+In this case, the packets are passed to both the kernel module and the raw
+socket(s).
+This should not be relied upon in portable programs, many other BSD
+socket implementation have limitations here.
+.P
+Linux never changes headers passed from the user (except for filling
+in some zeroed fields as described for
+.BR IP_HDRINCL ).
+This differs from many other implementations of raw sockets.
+.P
+Raw sockets are generally rather unportable and should be avoided in
+programs intended to be portable.
+.P
+Sending on raw sockets should take the IP protocol from
+.IR sin_port ;
+this ability was lost in Linux 2.2.
+The workaround is to use
+.BR IP_HDRINCL .
+.SH BUGS
+Transparent proxy extensions are not described.
+.P
+When the
+.B IP_HDRINCL
+option is set, datagrams will not be fragmented and are limited to
+the interface MTU.
+.P
+Setting the IP protocol for sending in
+.I sin_port
+got lost in Linux 2.2.
+The protocol that the socket was bound to or that
+was specified in the initial
+.BR socket (2)
+call is always used.
+.\" .SH AUTHORS
+.\" This man page was written by Andi Kleen.
+.SH SEE ALSO
+.BR recvmsg (2),
+.BR sendmsg (2),
+.BR capabilities (7),
+.BR ip (7),
+.BR socket (7)
+.P
+.B RFC\ 1191
+for path MTU discovery.
+.B RFC\ 791
+and the
+.I <linux/ip.h>
+header file for the IP protocol.
diff --git a/man/man7/regex.7 b/man/man7/regex.7
new file mode 100644
index 000000000..a579dbe62
--- /dev/null
+++ b/man/man7/regex.7
@@ -0,0 +1,293 @@
+'\" t
+.\" From Henry Spencer's regex package (as found in the apache
+.\" distribution). The package carries the following copyright:
+.\"
+.\"  Copyright 1992, 1993, 1994 Henry Spencer.  All rights reserved.
+.\" %%%LICENSE_START(MISC)
+.\"  This software is not subject to any license of the American Telephone
+.\"  and Telegraph Company or of the Regents of the University of California.
+.\"
+.\"  Permission is granted to anyone to use this software for any purpose
+.\"  on any computer system, and to alter it and redistribute it, subject
+.\"  to the following restrictions:
+.\"
+.\"  1. The author is not responsible for the consequences of use of this
+.\"     software, no matter how awful, even if they arise from flaws in it.
+.\"
+.\"  2. The origin of this software must not be misrepresented, either by
+.\"     explicit claim or by omission.  Since few users ever read sources,
+.\"     credits must appear in the documentation.
+.\"
+.\"  3. Altered versions must be plainly marked as such, and must not be
+.\"     misrepresented as being the original software.  Since few users
+.\"     ever read sources, credits must appear in the documentation.
+.\"
+.\"  4. This notice may not be removed or altered.
+.\" %%%LICENSE_END
+.\"
+.\" In order to comply with `credits must appear in the documentation'
+.\" I added an AUTHOR paragraph below - aeb.
+.\"
+.\" In the default nroff environment there is no dagger \(dg.
+.\"
+.\" 2005-05-11 Removed discussion of `[[:<:]]' and `[[:>:]]', which
+.\" 	appear not to be in the glibc implementation of regcomp
+.\"
+.ie t .ds dg \(dg
+.el .ds dg (!)
+.TH regex 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+regex \- POSIX.2 regular expressions
+.SH DESCRIPTION
+Regular expressions ("RE"s),
+as defined in POSIX.2, come in two forms:
+modern REs (roughly those of
+.BR egrep (1);
+POSIX.2 calls these "extended" REs)
+and obsolete REs (roughly those of
+.BR ed (1);
+POSIX.2 "basic" REs).
+Obsolete REs mostly exist for backward compatibility in some old programs;
+they will be discussed at the end.
+POSIX.2 leaves some aspects of RE syntax and semantics open;
+"\*(dg" marks decisions on these aspects that
+may not be fully portable to other POSIX.2 implementations.
+.P
+A (modern) RE is one\*(dg or more nonempty\*(dg \fIbranches\fR,
+separated by \[aq]|\[aq].
+It matches anything that matches one of the branches.
+.P
+A branch is one\*(dg or more \fIpieces\fR, concatenated.
+It matches a match for the first, followed by a match for the second,
+and so on.
+.P
+A piece is an \fIatom\fR possibly followed
+by a single\*(dg \[aq]*\[aq], \[aq]+\[aq], \[aq]?\[aq], or \fIbound\fR.
+An atom followed by \[aq]*\[aq]
+matches a sequence of 0 or more matches of the atom.
+An atom followed by \[aq]+\[aq]
+matches a sequence of 1 or more matches of the atom.
+An atom followed by \[aq]?\[aq]
+matches a sequence of 0 or 1 matches of the atom.
+.P
+A \fIbound\fR is \[aq]{\[aq] followed by an unsigned decimal integer,
+possibly followed by \[aq],\[aq]
+possibly followed by another unsigned decimal integer,
+always followed by \[aq]}\[aq].
+The integers must lie between 0 and
+.B RE_DUP_MAX
+(255\*(dg) inclusive,
+and if there are two of them, the first may not exceed the second.
+An atom followed by a bound containing one integer \fIi\fR
+and no comma matches
+a sequence of exactly \fIi\fR matches of the atom.
+An atom followed by a bound
+containing one integer \fIi\fR and a comma matches
+a sequence of \fIi\fR or more matches of the atom.
+An atom followed by a bound
+containing two integers \fIi\fR and \fIj\fR matches
+a sequence of \fIi\fR through \fIj\fR (inclusive) matches of the atom.
+.P
+An atom is a regular expression enclosed in "\fI()\fP"
+(matching a match for the regular expression),
+an empty set of "\fI()\fP" (matching the null string)\*(dg,
+a \fIbracket expression\fR (see below),
+\[aq].\[aq] (matching any single character),
+\[aq]\[ha]\[aq] (matching the null string at the beginning of a line),
+\[aq]$\[aq] (matching the null string at the end of a line),
+a \[aq]\e\[aq] followed by one of the characters "\fI\[ha].[$()|*+?{\e\fP"
+(matching that character taken as an ordinary character),
+a \[aq]\e\[aq] followed by any other character\*(dg
+(matching that character taken as an ordinary character,
+as if the \[aq]\e\[aq] had not been present\*(dg),
+or a single character with no other significance (matching that character).
+A \[aq]{\[aq] followed by a character other than a digit
+is an ordinary character,
+not the beginning of a bound\*(dg.
+It is illegal to end an RE with \[aq]\e\[aq].
+.P
+A \fIbracket expression\fR is a list of characters enclosed in "\fI[]\fP".
+It normally matches any single character from the list (but see below).
+If the list begins with \[aq]\[ha]\[aq],
+it matches any single character
+(but see below) \fInot\fR from the rest of the list.
+If two characters in the list are separated by \[aq]\-\[aq], this is shorthand
+for the full \fIrange\fR of characters between those two (inclusive) in the
+collating sequence,
+for example, "\fI[0\-9]\fP" in ASCII matches any decimal digit.
+It is illegal\*(dg for two ranges to share an
+endpoint, for example, "\fIa\-c\-e\fP".
+Ranges are very collating-sequence-dependent,
+and portable programs should avoid relying on them.
+.P
+To include a literal \[aq]]\[aq] in the list, make it the first character
+(following a possible \[aq]\[ha]\[aq]).
+To include a literal \[aq]\-\[aq], make it the first or last character,
+or the second endpoint of a range.
+To use a literal \[aq]\-\[aq] as the first endpoint of a range,
+enclose it in "\fI[.\fP" and "\fI.]\fP"
+to make it a collating element (see below).
+With the exception of these and some combinations using \[aq][\[aq] (see next
+paragraphs), all other special characters, including \[aq]\e\[aq], lose their
+special significance within a bracket expression.
+.P
+Within a bracket expression, a collating element (a character,
+a multicharacter sequence that collates as if it were a single character,
+or a collating-sequence name for either)
+enclosed in "\fI[.\fP" and "\fI.]\fP" stands for the
+sequence of characters of that collating element.
+The sequence is a single element of the bracket expression's list.
+A bracket expression containing a multicharacter collating element
+can thus match more than one character,
+for example, if the collating sequence includes a "ch" collating element,
+then the RE "\fI[[.ch.]]*c\fP" matches the first five characters
+of "chchcc".
+.P
+Within a bracket expression, a collating element enclosed in "\fI[=\fP" and
+"\fI=]\fP" is an equivalence class, standing for the sequences of characters
+of all collating elements equivalent to that one, including itself.
+(If there are no other equivalent collating elements,
+the treatment is as if the enclosing delimiters
+were "\fI[.\fP" and "\fI.]\fP".)
+For example, if o and \(^o are the members of an equivalence class,
+then "\fI[[=o=]]\fP", "\fI[[=\(^o=]]\fP",
+and "\fI[o\(^o]\fP" are all synonymous.
+An equivalence class may not\*(dg be an endpoint
+of a range.
+.P
+Within a bracket expression, the name of a \fIcharacter class\fR enclosed
+in "\fI[:\fP" and "\fI:]\fP" stands for the list
+of all characters belonging to that
+class.
+Standard character class names are:
+.P
+.RS
+.TS
+l l l.
+alnum	digit	punct
+alpha	graph	space
+blank	lower	upper
+cntrl	print	xdigit
+.TE
+.RE
+.P
+These stand for the character classes defined in
+.BR wctype (3).
+A locale may provide others.
+A character class may not be used as an endpoint of a range.
+.\" As per http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=295666
+.\" The following does not seem to apply in the glibc implementation
+.\" .P
+.\" There are two special cases\*(dg of bracket expressions:
+.\" the bracket expressions "\fI[[:<:]]\fP" and "\fI[[:>:]]\fP" match
+.\" the null string at the beginning and end of a word respectively.
+.\" A word is defined as a sequence of
+.\" word characters
+.\" which is neither preceded nor followed by
+.\" word characters.
+.\" A word character is an
+.\" .I alnum
+.\" character (as defined by
+.\" .BR wctype (3))
+.\" or an underscore.
+.\" This is an extension,
+.\" compatible with but not specified by POSIX.2,
+.\" and should be used with
+.\" caution in software intended to be portable to other systems.
+.P
+In the event that an RE could match more than one substring of a given
+string,
+the RE matches the one starting earliest in the string.
+If the RE could match more than one substring starting at that point,
+it matches the longest.
+Subexpressions also match the longest possible substrings, subject to
+the constraint that the whole match be as long as possible,
+with subexpressions starting earlier in the RE taking priority over
+ones starting later.
+Note that higher-level subexpressions thus take priority over
+their lower-level component subexpressions.
+.P
+Match lengths are measured in characters, not collating elements.
+A null string is considered longer than no match at all.
+For example,
+"\fIbb*\fP" matches the three middle characters of "abbbc",
+"\fI(wee|week)(knights|nights)\fP"
+matches all ten characters of "weeknights",
+when "\fI(.*).*\fP" is matched against "abc" the parenthesized subexpression
+matches all three characters, and
+when "\fI(a*)*\fP" is matched against "bc"
+both the whole RE and the parenthesized
+subexpression match the null string.
+.P
+If case-independent matching is specified,
+the effect is much as if all case distinctions had vanished from the
+alphabet.
+When an alphabetic that exists in multiple cases appears as an
+ordinary character outside a bracket expression, it is effectively
+transformed into a bracket expression containing both cases,
+for example, \[aq]x\[aq] becomes "\fI[xX]\fP".
+When it appears inside a bracket expression, all case counterparts
+of it are added to the bracket expression, so that, for example, "\fI[x]\fP"
+becomes "\fI[xX]\fP" and "\fI[\[ha]x]\fP" becomes "\fI[\[ha]xX]\fP".
+.P
+No particular limit is imposed on the length of REs\*(dg.
+Programs intended to be portable should not employ REs longer
+than 256 bytes,
+as an implementation can refuse to accept such REs and remain
+POSIX-compliant.
+.P
+Obsolete ("basic") regular expressions differ in several respects.
+\[aq]|\[aq], \[aq]+\[aq], and \[aq]?\[aq] are
+ordinary characters and there is no equivalent
+for their functionality.
+The delimiters for bounds are "\fI\e{\fP" and "\fI\e}\fP",
+with \[aq]{\[aq] and \[aq]}\[aq] by themselves ordinary characters.
+The parentheses for nested subexpressions are "\fI\e(\fP" and "\fI\e)\fP",
+with \[aq](\[aq] and \[aq])\[aq] by themselves ordinary characters.
+\[aq]\[ha]\[aq] is an ordinary character except at the beginning of the
+RE or\*(dg the beginning of a parenthesized subexpression,
+\[aq]$\[aq] is an ordinary character except at the end of the
+RE or\*(dg the end of a parenthesized subexpression,
+and \[aq]*\[aq] is an ordinary character if it appears at the beginning of the
+RE or the beginning of a parenthesized subexpression
+(after a possible leading \[aq]\[ha]\[aq]).
+.P
+Finally, there is one new type of atom, a \fIback reference\fR:
+\[aq]\e\[aq] followed by a nonzero decimal digit \fId\fR
+matches the same sequence of characters
+matched by the \fId\fRth parenthesized subexpression
+(numbering subexpressions by the positions of their opening parentheses,
+left to right),
+so that, for example, "\fI\e([bc]\e)\e1\fP" matches "bb" or "cc" but not "bc".
+.SH BUGS
+Having two kinds of REs is a botch.
+.P
+The current POSIX.2 spec says that \[aq])\[aq] is an ordinary character in
+the absence of an unmatched \[aq](\[aq];
+this was an unintentional result of a wording error,
+and change is likely.
+Avoid relying on it.
+.P
+Back references are a dreadful botch,
+posing major problems for efficient implementations.
+They are also somewhat vaguely defined
+(does
+"\fIa\e(\e(b\e)*\e2\e)*d\fP" match "abbbd"?).
+Avoid using them.
+.P
+POSIX.2's specification of case-independent matching is vague.
+The "one case implies all cases" definition given above
+is current consensus among implementors as to the right interpretation.
+.\" As per http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=295666
+.\" The following does not seem to apply in the glibc implementation
+.\" .P
+.\" The syntax for word boundaries is incredibly ugly.
+.SH AUTHOR
+.\" Sigh... The page license means we must have the author's name
+.\" in the formatted output.
+This page was taken from Henry Spencer's regex package.
+.SH SEE ALSO
+.BR grep (1),
+.BR regex (3)
+.P
+POSIX.2, section 2.8 (Regular Expression Notation).
diff --git a/man/man7/rtld-audit.7 b/man/man7/rtld-audit.7
new file mode 100644
index 000000000..0aab7ca18
--- /dev/null
+++ b/man/man7/rtld-audit.7
@@ -0,0 +1,606 @@
+.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2009-01-12, mtk, Created
+.\"
+.TH RTLD-AUDIT 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rtld\-audit \- auditing API for the dynamic linker
+.SH SYNOPSIS
+.nf
+.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
+.B #include <link.h>
+.fi
+.SH DESCRIPTION
+The GNU dynamic linker (run-time linker)
+provides an auditing API that allows an application
+to be notified when various dynamic linking events occur.
+This API is very similar to the auditing interface provided by the
+Solaris run-time linker.
+The necessary constants and prototypes are defined by including
+.IR <link.h> .
+.P
+To use this interface, the programmer creates a shared library
+that implements a standard set of function names.
+Not all of the functions need to be implemented: in most cases,
+if the programmer is not interested in a particular class of auditing event,
+then no implementation needs to be provided for the corresponding
+auditing function.
+.P
+To employ the auditing interface, the environment variable
+.B LD_AUDIT
+must be defined to contain a colon-separated list of shared libraries,
+each of which can implement (parts of) the auditing API.
+When an auditable event occurs,
+the corresponding function is invoked in each library,
+in the order that the libraries are listed.
+.SS la_version()
+\&
+.nf
+.BI "unsigned int la_version(unsigned int " version );
+.fi
+.P
+This is the only function that
+.I must
+be defined by an auditing library:
+it performs the initial handshake between the dynamic linker and
+the auditing library.
+When invoking this function, the dynamic linker passes, in
+.IR version ,
+the highest version of the auditing interface that the linker supports.
+.P
+A typical implementation of this function simply returns the constant
+.BR LAV_CURRENT ,
+which indicates the version of
+.I <link.h>
+that was used to build the audit module.
+If the dynamic linker does
+not support this version of the audit interface, it will refuse to
+activate this audit module.
+If the function returns zero, the dynamic
+linker also does not activate this audit module.
+.P
+In order to enable backwards compatibility with older dynamic linkers,
+an audit module can examine the
+.I version
+argument and return an earlier version than
+.BR LAV_CURRENT ,
+assuming the module can adjust its implementation to match the
+requirements of the previous version of the audit interface.
+The
+.B la_version
+function should not return the value of
+.I version
+without further checks because it could correspond to an interface
+that does not match the
+.I <link.h>
+definitions used to build the audit module.
+.SS la_objsearch()
+\&
+.nf
+.BI "char *la_objsearch(const char *" name ", uintptr_t *" cookie ,
+.BI "                   unsigned int " flag );
+.fi
+.P
+The dynamic linker invokes this function to inform the auditing library
+that it is about to search for a shared object.
+The
+.I name
+argument is the filename or pathname that is to be searched for.
+.I cookie
+identifies the shared object that initiated the search.
+.I flag
+is set to one of the following values:
+.TP 17
+.B LA_SER_ORIG
+This is the original name that is being searched for.
+Typically, this name comes from an ELF
+.B DT_NEEDED
+entry, or is the
+.I filename
+argument given to
+.BR dlopen (3).
+.TP
+.B LA_SER_LIBPATH
+.I name
+was created using a directory specified in
+.BR LD_LIBRARY_PATH .
+.TP
+.B LA_SER_RUNPATH
+.I name
+was created using a directory specified in an ELF
+.B DT_RPATH
+or
+.B DT_RUNPATH
+list.
+.TP
+.B LA_SER_CONFIG
+.I name
+was found via the
+.BR ldconfig (8)
+cache
+.RI ( /etc/ld.so.cache ).
+.TP
+.B LA_SER_DEFAULT
+.I name
+was found via a search of one of the default directories.
+.TP
+.B LA_SER_SECURE
+.I name
+is specific to a secure object (unused on Linux).
+.P
+As its function result,
+.BR la_objsearch ()
+returns the pathname that the dynamic linker should use
+for further processing.
+If NULL is returned, then this pathname is ignored for further processing.
+If this audit library simply intends to monitor search paths, then
+.I name
+should be returned.
+.SS la_activity()
+\&
+.nf
+.BI "void la_activity( uintptr_t *" cookie ", unsigned int "flag  );
+.fi
+.P
+The dynamic linker calls this function to inform the auditing library
+that link-map activity is occurring.
+.I cookie
+identifies the object at the head of the link map.
+When the dynamic linker invokes this function,
+.I flag
+is set to one of the following values:
+.TP 19
+.B LA_ACT_ADD
+New objects are being added to the link map.
+.TP
+.B LA_ACT_DELETE
+Objects are being removed from the link map.
+.TP
+.B LA_ACT_CONSISTENT
+Link-map activity has been completed: the map is once again consistent.
+.SS la_objopen()
+\&
+.nf
+.BI "unsigned int la_objopen(struct link_map *" map ", Lmid_t " lmid ,
+.BI "                        uintptr_t *" cookie );
+.fi
+.P
+The dynamic linker calls this function when a new shared object is loaded.
+The
+.I map
+argument is a pointer to a link-map structure that describes the object.
+The
+.I lmid
+field has one of the following values
+.TP 17
+.B LM_ID_BASE
+Link map is part of the initial namespace.
+.TP
+.B LM_ID_NEWLM
+Link map is part of a new namespace requested via
+.BR dlmopen (3).
+.P
+.I cookie
+is a pointer to an identifier for this object.
+The identifier is provided to later calls to functions
+in the auditing library in order to identify this object.
+This identifier is initialized to point to object's link map,
+but the audit library can change the identifier to some other value
+that it may prefer to use to identify the object.
+.P
+As its return value,
+.BR la_objopen ()
+returns a bit mask created by ORing zero or more of the
+following constants,
+which allow the auditing library to select the objects to be monitored by
+.BR la_symbind* ():
+.TP 17
+.B LA_FLG_BINDTO
+Audit symbol bindings to this object.
+.TP
+.B LA_FLG_BINDFROM
+Audit symbol bindings from this object.
+.P
+A return value of 0 from
+.BR la_objopen ()
+indicates that no symbol bindings should be audited for this object.
+.SS la_objclose()
+\&
+.nf
+.BI "unsigned int la_objclose(uintptr_t *" cookie );
+.fi
+.P
+The dynamic linker invokes this function after any finalization
+code for the object has been executed,
+before the object is unloaded.
+The
+.I cookie
+argument is the identifier obtained from a previous invocation of
+.BR la_objopen ().
+.P
+In the current implementation, the value returned by
+.BR la_objclose ()
+is ignored.
+.SS la_preinit()
+\&
+.nf
+.BI "void la_preinit(uintptr_t *" cookie );
+.fi
+.P
+The dynamic linker invokes this function after all shared objects
+have been loaded, before control is passed to the application
+(i.e., before calling
+.IR main ()).
+Note that
+.IR main ()
+may still later dynamically load objects using
+.BR dlopen (3).
+.SS la_symbind*()
+\&
+.nf
+.BI "uintptr_t la_symbind32(Elf32_Sym *" sym ", unsigned int " ndx ,
+.BI "                       uintptr_t *" refcook ", uintptr_t *" defcook ,
+.BI "                       unsigned int *" flags ", const char *" symname );
+.BI "uintptr_t la_symbind64(Elf64_Sym *" sym ", unsigned int " ndx ,
+.BI "                       uintptr_t *" refcook ", uintptr_t *" defcook ,
+.BI "                       unsigned int *" flags ", const char *" symname );
+.fi
+.P
+The dynamic linker invokes one of these functions
+when a symbol binding occurs between two shared objects
+that have been marked for auditing notification by
+.BR la_objopen ().
+The
+.BR la_symbind32 ()
+function is employed on 32-bit platforms;
+the
+.BR la_symbind64 ()
+function is employed on 64-bit platforms.
+.P
+The
+.I sym
+argument is a pointer to a structure
+that provides information about the symbol being bound.
+The structure definition is shown in
+.IR <elf.h> .
+Among the fields of this structure,
+.I st_value
+indicates the address to which the symbol is bound.
+.P
+The
+.I ndx
+argument gives the index of the symbol in the symbol table
+of the bound shared object.
+.P
+The
+.I refcook
+argument identifies the shared object that is making the symbol reference;
+this is the same identifier that is provided to the
+.BR la_objopen ()
+function that returned
+.BR LA_FLG_BINDFROM .
+The
+.I defcook
+argument identifies the shared object that defines the referenced symbol;
+this is the same identifier that is provided to the
+.BR la_objopen ()
+function that returned
+.BR LA_FLG_BINDTO .
+.P
+The
+.I symname
+argument points a string containing the name of the symbol.
+.P
+The
+.I flags
+argument is a bit mask that both provides information about the symbol
+and can be used to modify further auditing of this
+PLT (Procedure Linkage Table) entry.
+The dynamic linker may supply the following bit values in this argument:
+.\" LA_SYMB_STRUCTCALL appears to be unused
+.TP 22
+.B LA_SYMB_DLSYM
+The binding resulted from a call to
+.BR dlsym (3).
+.TP
+.B LA_SYMB_ALTVALUE
+A previous
+.BR la_symbind* ()
+call returned an alternate value for this symbol.
+.P
+By default, if the auditing library implements
+.BR la_pltenter ()
+and
+.BR la_pltexit ()
+functions (see below), then these functions are invoked, after
+.BR la_symbind (),
+for PLT entries, each time the symbol is referenced.
+.\" pltenter/pltexit are called for non-dynamically loaded libraries,
+.\" but don't seem to be called for dynamically loaded libs?
+.\" Is this the same on Solaris?
+The following flags can be ORed into
+.I *flags
+to change this default behavior:
+.TP 22
+.B LA_SYMB_NOPLTENTER
+Don't call
+.BR la_pltenter ()
+for this symbol.
+.TP 22
+.B LA_SYMB_NOPLTEXIT
+Don't call
+.BR la_pltexit ()
+for this symbol.
+.P
+The return value of
+.BR la_symbind32 ()
+and
+.BR la_symbind64 ()
+is the address to which control should be passed after the function returns.
+If the auditing library is simply monitoring symbol bindings,
+then it should return
+.IR sym\->st_value .
+A different value may be returned if the library wishes to direct control
+to an alternate location.
+.SS la_pltenter()
+The precise name and argument types for this function
+depend on the hardware platform.
+(The appropriate definition is supplied by
+.IR <link.h> .)
+Here is the definition for x86-32:
+.P
+.nf
+.BI "Elf32_Addr la_i86_gnu_pltenter(Elf32_Sym *" sym ", unsigned int " ndx ,
+.BI "                 uintptr_t *" refcook ", uintptr_t *" defcook ,
+.BI "                 La_i86_regs *" regs ", unsigned int *" flags ,
+.BI "                 const char *" symname ", long *" framesizep );
+.fi
+.P
+This function is invoked just before a PLT entry is called,
+between two shared objects that have been marked for binding notification.
+.P
+The
+.IR sym ,
+.IR ndx ,
+.IR refcook ,
+.IR defcook ,
+and
+.I symname
+are as for
+.BR la_symbind* ().
+.P
+The
+.I regs
+argument points to a structure (defined in
+.IR <link.h> )
+containing the values of registers to be used for
+the call to this PLT entry.
+.P
+The
+.I flags
+argument points to a bit mask that conveys information about,
+and can be used to modify subsequent auditing of, this PLT entry, as for
+.BR la_symbind* ().
+.P
+.\" FIXME . Is the following correct?
+The
+.I framesizep
+argument points to a
+.I long\~int
+buffer that can be used to explicitly set the frame size
+used for the call to this PLT entry.
+If different
+.BR la_pltenter ()
+invocations for this symbol return different values,
+then the maximum returned value is used.
+The
+.BR la_pltexit ()
+function is called only if this buffer is
+explicitly set to a suitable value.
+.P
+The return value of
+.BR la_pltenter ()
+is as for
+.BR la_symbind* ().
+.SS la_pltexit()
+The precise name and argument types for this function
+depend on the hardware platform.
+(The appropriate definition is supplied by
+.IR <link.h> .)
+Here is the definition for x86-32:
+.P
+.nf
+.BI "unsigned int la_i86_gnu_pltexit(Elf32_Sym *" sym ", unsigned int " ndx ,
+.BI "                 uintptr_t *" refcook ", uintptr_t *" defcook ,
+.BI "                 const La_i86_regs *" inregs ", La_i86_retval *" outregs ,
+.BI "                 const char *" symname );
+.fi
+.P
+This function is called when a PLT entry,
+made between two shared objects that have been marked
+for binding notification, returns.
+The function is called just before control returns to the caller
+of the PLT entry.
+.P
+The
+.IR sym ,
+.IR ndx ,
+.IR refcook ,
+.IR defcook ,
+and
+.I symname
+are as for
+.BR la_symbind* ().
+.P
+The
+.I inregs
+argument points to a structure (defined in
+.IR <link.h> )
+containing the values of registers used for the call to this PLT entry.
+The
+.I outregs
+argument points to a structure (defined in
+.IR <link.h> )
+containing return values for the call to this PLT entry.
+These values can be modified by the caller,
+and the changes will be visible to the caller of the PLT entry.
+.P
+In the current GNU implementation, the return value of
+.BR la_pltexit ()
+is ignored.
+.\" This differs from Solaris, where an audit library that monitors
+.\" symbol binding should return the value of the 'retval' argument
+.\" (not provided by GNU, but equivalent to returning outregs->lrv_eax
+.\" on (say) x86-32).
+.SH VERSIONS
+This API is very similar to the Solaris API
+described in the Solaris
+.IR "Linker and Libraries Guide" ,
+in the chapter
+.IR "Runtime Linker Auditing Interface" .
+.SH STANDARDS
+None.
+.SH NOTES
+Note the following differences from the Solaris dynamic linker
+auditing API:
+.IP \[bu] 3
+The Solaris
+.BR la_objfilter ()
+interface is not supported by the GNU implementation.
+.IP \[bu]
+The Solaris
+.BR la_symbind32 ()
+and
+.BR la_pltexit ()
+functions do not provide a
+.I symname
+argument.
+.IP \[bu]
+The Solaris
+.BR la_pltexit ()
+function does not provide
+.I inregs
+and
+.I outregs
+arguments (but does provide a
+.I retval
+argument with the function return value).
+.SH BUGS
+In glibc versions up to and include 2.9,
+specifying more than one audit library in
+.B LD_AUDIT
+results in a run-time crash.
+This is reportedly fixed in glibc 2.10.
+.\" FIXME . Specifying multiple audit libraries doesn't work on GNU.
+.\" My simple tests on Solaris work okay, but not on Linux -- mtk, Jan 2009
+.\" glibc bug filed: http://sourceware.org/bugzilla/show_bug.cgi?id=9733
+.\" Reportedly, this is fixed on 16 Mar 2009 (i.e., for glibc 2.10)
+.SH EXAMPLES
+.EX
+#include <link.h>
+#include <stdio.h>
+\&
+unsigned int
+la_version(unsigned int version)
+{
+    printf("la_version(): version = %u; LAV_CURRENT = %u\en",
+            version, LAV_CURRENT);
+\&
+    return LAV_CURRENT;
+}
+\&
+char *
+la_objsearch(const char *name, uintptr_t *cookie, unsigned int flag)
+{
+    printf("la_objsearch(): name = %s; cookie = %p", name, cookie);
+    printf("; flag = %s\en",
+            (flag == LA_SER_ORIG) ?    "LA_SER_ORIG" :
+            (flag == LA_SER_LIBPATH) ? "LA_SER_LIBPATH" :
+            (flag == LA_SER_RUNPATH) ? "LA_SER_RUNPATH" :
+            (flag == LA_SER_DEFAULT) ? "LA_SER_DEFAULT" :
+            (flag == LA_SER_CONFIG) ?  "LA_SER_CONFIG" :
+            (flag == LA_SER_SECURE) ?  "LA_SER_SECURE" :
+            "???");
+\&
+    return name;
+}
+\&
+void
+la_activity (uintptr_t *cookie, unsigned int flag)
+{
+    printf("la_activity(): cookie = %p; flag = %s\en", cookie,
+            (flag == LA_ACT_CONSISTENT) ? "LA_ACT_CONSISTENT" :
+            (flag == LA_ACT_ADD) ?        "LA_ACT_ADD" :
+            (flag == LA_ACT_DELETE) ?     "LA_ACT_DELETE" :
+            "???");
+}
+\&
+unsigned int
+la_objopen(struct link_map *map, Lmid_t lmid, uintptr_t *cookie)
+{
+    printf("la_objopen(): loading \e"%s\e"; lmid = %s; cookie=%p\en",
+            map\->l_name,
+            (lmid == LM_ID_BASE) ?  "LM_ID_BASE" :
+            (lmid == LM_ID_NEWLM) ? "LM_ID_NEWLM" :
+            "???",
+            cookie);
+\&
+    return LA_FLG_BINDTO | LA_FLG_BINDFROM;
+}
+\&
+unsigned int
+la_objclose (uintptr_t *cookie)
+{
+    printf("la_objclose(): %p\en", cookie);
+\&
+    return 0;
+}
+\&
+void
+la_preinit(uintptr_t *cookie)
+{
+    printf("la_preinit(): %p\en", cookie);
+}
+\&
+uintptr_t
+la_symbind32(Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
+        uintptr_t *defcook, unsigned int *flags, const char *symname)
+{
+    printf("la_symbind32(): symname = %s; sym\->st_value = %p\en",
+            symname, sym\->st_value);
+    printf("        ndx = %u; flags = %#x", ndx, *flags);
+    printf("; refcook = %p; defcook = %p\en", refcook, defcook);
+\&
+    return sym\->st_value;
+}
+\&
+uintptr_t
+la_symbind64(Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
+        uintptr_t *defcook, unsigned int *flags, const char *symname)
+{
+    printf("la_symbind64(): symname = %s; sym\->st_value = %p\en",
+            symname, sym\->st_value);
+    printf("        ndx = %u; flags = %#x", ndx, *flags);
+    printf("; refcook = %p; defcook = %p\en", refcook, defcook);
+\&
+    return sym\->st_value;
+}
+\&
+Elf32_Addr
+la_i86_gnu_pltenter(Elf32_Sym *sym, unsigned int ndx,
+        uintptr_t *refcook, uintptr_t *defcook, La_i86_regs *regs,
+        unsigned int *flags, const char *symname, long *framesizep)
+{
+    printf("la_i86_gnu_pltenter(): %s (%p)\en", symname, sym\->st_value);
+\&
+    return sym\->st_value;
+}
+.EE
+.SH SEE ALSO
+.BR ldd (1),
+.BR dlopen (3),
+.BR ld.so (8),
+.BR ldconfig (8)
diff --git a/man/man7/rtnetlink.7 b/man/man7/rtnetlink.7
new file mode 100644
index 000000000..86ed459bb
--- /dev/null
+++ b/man/man7/rtnetlink.7
@@ -0,0 +1,590 @@
+'\" t
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" Based on the original comments from Alexey Kuznetsov, written with
+.\" help from Matthew Wilcox.
+.\" $Id: rtnetlink.7,v 1.8 2000/01/22 01:55:04 freitag Exp $
+.\"
+.TH rtnetlink 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+rtnetlink \- Linux routing socket
+.SH SYNOPSIS
+.nf
+.B #include <asm/types.h>
+.B #include <linux/netlink.h>
+.B #include <linux/rtnetlink.h>
+.B #include <sys/socket.h>
+.P
+.BI "rtnetlink_socket = socket(AF_NETLINK, int " socket_type ", NETLINK_ROUTE);"
+.fi
+.SH DESCRIPTION
+Rtnetlink allows the kernel's routing tables to be read and altered.
+It is used within the kernel to communicate between
+various subsystems, though this usage is not documented here, and for
+communication with user-space programs.
+Network routes, IP addresses, link parameters, neighbor setups, queueing
+disciplines, traffic classes and packet classifiers may all be controlled
+through
+.B NETLINK_ROUTE
+sockets.
+It is based on netlink messages; see
+.BR netlink (7)
+for more information.
+.\" FIXME . ? all these macros could be moved to rtnetlink(3)
+.SS Routing attributes
+Some rtnetlink messages have optional attributes after the initial header:
+.P
+.in +4n
+.EX
+struct rtattr {
+    unsigned short rta_len;    /* Length of option */
+    unsigned short rta_type;   /* Type of option */
+    /* Data follows */
+};
+.EE
+.in
+.P
+These attributes should be manipulated using only the RTA_* macros
+or libnetlink, see
+.BR rtnetlink (3).
+.SS Messages
+Rtnetlink consists of these message types
+(in addition to standard netlink messages):
+.TP
+.B RTM_NEWLINK
+.TQ
+.B RTM_DELLINK
+.TQ
+.B RTM_GETLINK
+Create, remove, or get information about a specific network interface.
+These messages contain an
+.I ifinfomsg
+structure followed by a series of
+.I rtattr
+structures.
+.IP
+.EX
+struct ifinfomsg {
+    unsigned char  ifi_family; /* AF_UNSPEC */
+    unsigned short ifi_type;   /* Device type */
+    int            ifi_index;  /* Interface index */
+    unsigned int   ifi_flags;  /* Device flags  */
+    unsigned int   ifi_change; /* change mask */
+};
+.EE
+.IP
+.\" FIXME Document ifinfomsg.ifi_type
+.I ifi_flags
+contains the device flags, see
+.BR netdevice (7);
+.I ifi_index
+is the unique interface index
+(since Linux 3.7, it is possible to feed a nonzero value with the
+.B RTM_NEWLINK
+message, thus creating a link with the given
+.IR ifindex );
+.I ifi_change
+is reserved for future use and should be always set to 0xFFFFFFFF.
+.TS
+tab(:);
+c s s
+lb l l.
+Routing attributes
+rta_type:Value type:Description
+_
+IFLA_UNSPEC:-:unspecified
+IFLA_ADDRESS:hardware address:interface L2 address
+IFLA_BROADCAST:hardware address:L2 broadcast address
+IFLA_IFNAME:asciiz string:Device name
+IFLA_MTU:unsigned int:MTU of the device
+IFLA_LINK:int:Link type
+IFLA_QDISC:asciiz string:Queueing discipline
+IFLA_STATS:T{
+see below
+T}:Interface Statistics
+IFLA_PERM_ADDRESS:hardware address:T{
+hardware address provided by device (since Linux 5.5)
+T}
+.TE
+.IP
+The value type for
+.B IFLA_STATS
+is
+.I struct rtnl_link_stats
+.RI ( "struct net_device_stats"
+in Linux 2.4 and earlier).
+.TP
+.B RTM_NEWADDR
+.TQ
+.B RTM_DELADDR
+.TQ
+.B RTM_GETADDR
+Add, remove, or receive information about an IP address associated with
+an interface.
+In Linux 2.2, an interface can carry multiple IP addresses,
+this replaces the alias device concept in Linux 2.0.
+In Linux 2.2, these messages
+support IPv4 and IPv6 addresses.
+They contain an
+.I ifaddrmsg
+structure, optionally followed by
+.I rtattr
+routing attributes.
+.IP
+.EX
+struct ifaddrmsg {
+    unsigned char ifa_family;    /* Address type */
+    unsigned char ifa_prefixlen; /* Prefixlength of address */
+    unsigned char ifa_flags;     /* Address flags */
+    unsigned char ifa_scope;     /* Address scope */
+    unsigned int  ifa_index;     /* Interface index */
+};
+.EE
+.IP
+.I ifa_family
+is the address family type (currently
+.B AF_INET
+or
+.BR AF_INET6 ),
+.I ifa_prefixlen
+is the length of the address mask of the address if defined for the
+family (like for IPv4),
+.I ifa_scope
+is the address scope,
+.I ifa_index
+is the interface index of the interface the address is associated with.
+.I ifa_flags
+is a flag word of
+.B IFA_F_SECONDARY
+for secondary address (old alias interface),
+.B IFA_F_PERMANENT
+for a permanent address set by the user and other undocumented flags.
+.TS
+tab(:);
+c s s
+lb l l.
+Attributes
+rta_type:Value type:Description
+_
+IFA_UNSPEC:-:unspecified
+IFA_ADDRESS:raw protocol address:interface address
+IFA_LOCAL:raw protocol address:local address
+IFA_LABEL:asciiz string:name of the interface
+IFA_BROADCAST:raw protocol address:broadcast address
+IFA_ANYCAST:raw protocol address:anycast address
+IFA_CACHEINFO:struct ifa_cacheinfo:Address information
+.TE
+.\" FIXME Document struct ifa_cacheinfo
+.TP
+.B RTM_NEWROUTE
+.TQ
+.B RTM_DELROUTE
+.TQ
+.B RTM_GETROUTE
+Create, remove, or receive information about a network route.
+These messages contain an
+.I rtmsg
+structure with an optional sequence of
+.I rtattr
+structures following.
+For
+.BR RTM_GETROUTE ,
+setting
+.I rtm_dst_len
+and
+.I rtm_src_len
+to 0 means you get all entries for the specified routing table.
+For the other fields, except
+.I rtm_table
+and
+.IR rtm_protocol ,
+0 is the wildcard.
+.IP
+.EX
+struct rtmsg {
+    unsigned char rtm_family;   /* Address family of route */
+    unsigned char rtm_dst_len;  /* Length of destination */
+    unsigned char rtm_src_len;  /* Length of source */
+    unsigned char rtm_tos;      /* TOS filter */
+    unsigned char rtm_table;    /* Routing table ID;
+                                   see RTA_TABLE below */
+    unsigned char rtm_protocol; /* Routing protocol; see below */
+    unsigned char rtm_scope;    /* See below */
+    unsigned char rtm_type;     /* See below */
+\&
+    unsigned int  rtm_flags;
+};
+.EE
+.TS
+tab(:);
+lb l.
+rtm_type:Route type
+_
+RTN_UNSPEC:unknown route
+RTN_UNICAST:a gateway or direct route
+RTN_LOCAL:a local interface route
+RTN_BROADCAST:T{
+a local broadcast route (sent as a broadcast)
+T}
+RTN_ANYCAST:T{
+a local broadcast route (sent as a unicast)
+T}
+RTN_MULTICAST:a multicast route
+RTN_BLACKHOLE:a packet dropping route
+RTN_UNREACHABLE:an unreachable destination
+RTN_PROHIBIT:a packet rejection route
+RTN_THROW:continue routing lookup in another table
+RTN_NAT:a network address translation rule
+RTN_XRESOLVE:T{
+refer to an external resolver (not implemented)
+T}
+.TE
+.TS
+tab(:);
+lb l.
+rtm_protocol:Route origin
+_
+RTPROT_UNSPEC:unknown
+RTPROT_REDIRECT:T{
+by an ICMP redirect (currently unused)
+T}
+RTPROT_KERNEL:by the kernel
+RTPROT_BOOT:during boot
+RTPROT_STATIC:by the administrator
+.TE
+.IP
+Values larger than
+.B RTPROT_STATIC
+are not interpreted by the kernel, they are just for user information.
+They may be used to tag the source of a routing information or to
+distinguish between multiple routing daemons.
+See
+.I <linux/rtnetlink.h>
+for the routing daemon identifiers which are already assigned.
+.IP
+.I rtm_scope
+is the distance to the destination:
+.TS
+tab(:);
+lb l.
+RT_SCOPE_UNIVERSE:global route
+RT_SCOPE_SITE:T{
+interior route in the local autonomous system
+T}
+RT_SCOPE_LINK:route on this link
+RT_SCOPE_HOST:route on the local host
+RT_SCOPE_NOWHERE:destination doesn't exist
+.TE
+.IP
+The values between
+.B RT_SCOPE_UNIVERSE
+and
+.B RT_SCOPE_SITE
+are available to the user.
+.IP
+The
+.I rtm_flags
+have the following meanings:
+.TS
+tab(:);
+lb l.
+RTM_F_NOTIFY:T{
+if the route changes, notify the user via rtnetlink
+T}
+RTM_F_CLONED:route is cloned from another route
+RTM_F_EQUALIZE:a multipath equalizer (not yet implemented)
+.TE
+.IP
+.I rtm_table
+specifies the routing table
+.TS
+tab(:);
+lb l.
+RT_TABLE_UNSPEC:an unspecified routing table
+RT_TABLE_DEFAULT:the default table
+RT_TABLE_MAIN:the main table
+RT_TABLE_LOCAL:the local table
+.TE
+.IP
+The user may assign arbitrary values between
+.B RT_TABLE_UNSPEC
+and
+.BR RT_TABLE_DEFAULT .
+.\" Keep table on same page
+.bp +1
+.TS
+tab(:);
+c s s
+lb2 l2 l.
+Attributes
+rta_type:Value type:Description
+_
+RTA_UNSPEC:-:ignored
+RTA_DST:protocol address:Route destination address
+RTA_SRC:protocol address:Route source address
+RTA_IIF:int:Input interface index
+RTA_OIF:int:Output interface index
+RTA_GATEWAY:protocol address:The gateway of the route
+RTA_PRIORITY:int:Priority of route
+RTA_PREFSRC:protocol address:Preferred source address
+RTA_METRICS:int:Route metric
+RTA_MULTIPATH::T{
+Multipath nexthop data
+br
+(see below).
+T}
+RTA_PROTOINFO::No longer used
+RTA_FLOW:int:Route realm
+RTA_CACHEINFO:struct rta_cacheinfo:(see linux/rtnetlink.h)
+RTA_SESSION::No longer used
+RTA_MP_ALGO::No longer used
+RTA_TABLE:int:T{
+Routing table ID; if set,
+.br
+rtm_table is ignored
+T}
+RTA_MARK:int:
+RTA_MFC_STATS:struct rta_mfc_stats:(see linux/rtnetlink.h)
+RTA_VIA:struct rtvia:T{
+Gateway in different AF
+(see below)
+T}
+RTA_NEWDST:protocol address:T{
+Change packet
+destination address
+T}
+RTA_PREF:char:T{
+RFC4191 IPv6 router
+preference (see below)
+T}
+RTA_ENCAP_TYPE:short:T{
+Encapsulation type for
+.br
+lwtunnels (see below)
+T}
+RTA_ENCAP::Defined by RTA_ENCAP_TYPE
+RTA_EXPIRES:int:T{
+Expire time for IPv6
+routes (in seconds)
+T}
+.TE
+.IP
+.B RTA_MULTIPATH
+contains several packed instances of
+.I struct rtnexthop
+together with nested RTAs
+.RB ( RTA_GATEWAY ):
+.IP
+.in +4n
+.EX
+struct rtnexthop {
+    unsigned short rtnh_len;     /* Length of struct + length
+                                    of RTAs */
+    unsigned char  rtnh_flags;   /* Flags (see
+                                    linux/rtnetlink.h) */
+    unsigned char  rtnh_hops;    /* Nexthop priority */
+    int            rtnh_ifindex; /* Interface index for this
+                                    nexthop */
+}
+.EE
+.in
+.IP
+There exist a bunch of
+.B RTNH_*
+macros similar to
+.B RTA_*
+and
+.B NLHDR_*
+macros
+useful to handle these structures.
+.IP
+.in +4n
+.EX
+struct rtvia {
+    unsigned short rtvia_family;
+    unsigned char  rtvia_addr[0];
+};
+.EE
+.in
+.IP
+.I rtvia_addr
+is the address,
+.I rtvia_family
+is its family type.
+.IP
+.B RTA_PREF
+may contain values
+.BR ICMPV6_ROUTER_PREF_LOW ,
+.BR ICMPV6_ROUTER_PREF_MEDIUM ,
+and
+.B ICMPV6_ROUTER_PREF_HIGH
+defined incw
+.IR <linux/icmpv6.h> .
+.IP
+.B RTA_ENCAP_TYPE
+may contain values
+.BR LWTUNNEL_ENCAP_MPLS ,
+.BR LWTUNNEL_ENCAP_IP ,
+.BR LWTUNNEL_ENCAP_ILA ,
+or
+.B LWTUNNEL_ENCAP_IP6
+defined in
+.IR <linux/lwtunnel.h> .
+.IP
+.B Fill these values in!
+.TP
+.B RTM_NEWNEIGH
+.TQ
+.B RTM_DELNEIGH
+.TQ
+.B RTM_GETNEIGH
+Add, remove, or receive information about a neighbor table
+entry (e.g., an ARP entry).
+The message contains an
+.I ndmsg
+structure.
+.IP
+.EX
+struct ndmsg {
+    unsigned char ndm_family;
+    int           ndm_ifindex;  /* Interface index */
+    __u16         ndm_state;    /* State */
+    __u8          ndm_flags;    /* Flags */
+    __u8          ndm_type;
+};
+\&
+struct nda_cacheinfo {
+    __u32         ndm_confirmed;
+    __u32         ndm_used;
+    __u32         ndm_updated;
+    __u32         ndm_refcnt;
+};
+.EE
+.IP
+.I ndm_state
+is a bit mask of the following states:
+.TS
+tab(:);
+lb l.
+NUD_INCOMPLETE:a currently resolving cache entry
+NUD_REACHABLE:a confirmed working cache entry
+NUD_STALE:an expired cache entry
+NUD_DELAY:an entry waiting for a timer
+NUD_PROBE:a cache entry that is currently reprobed
+NUD_FAILED:an invalid cache entry
+NUD_NOARP:a device with no destination cache
+NUD_PERMANENT:a static entry
+.TE
+.IP
+Valid
+.I ndm_flags
+are:
+.TS
+tab(:);
+lb l.
+NTF_PROXY:a proxy arp entry
+NTF_ROUTER:an IPv6 router
+.TE
+.IP
+.\" FIXME .
+.\" document the members of the struct better
+The
+.I rtattr
+struct has the following meanings for the
+.I rta_type
+field:
+.TS
+tab(:);
+lb l.
+NDA_UNSPEC:unknown type
+NDA_DST:a neighbor cache n/w layer destination address
+NDA_LLADDR:a neighbor cache link layer address
+NDA_CACHEINFO:cache statistics
+.TE
+.IP
+If the
+.I rta_type
+field is
+.BR NDA_CACHEINFO ,
+then a
+.I struct nda_cacheinfo
+header follows.
+.TP
+.B RTM_NEWRULE
+.TQ
+.B RTM_DELRULE
+.TQ
+.B RTM_GETRULE
+Add, delete, or retrieve a routing rule.
+Carries a
+.I struct rtmsg
+.TP
+.B RTM_NEWQDISC
+.TQ
+.B RTM_DELQDISC
+.TQ
+.B RTM_GETQDISC
+Add, remove, or get a queueing discipline.
+The message contains a
+.I struct tcmsg
+and may be followed by a series of
+attributes.
+.IP
+.EX
+struct tcmsg {
+    unsigned char    tcm_family;
+    int              tcm_ifindex;   /* interface index */
+    __u32            tcm_handle;    /* Qdisc handle */
+    __u32            tcm_parent;    /* Parent qdisc */
+    __u32            tcm_info;
+};
+.EE
+.TS
+tab(:);
+c s s
+lb2 l2 l.
+Attributes
+rta_type:Value type:Description
+_
+TCA_UNSPEC:-:unspecified
+TCA_KIND:asciiz string:Name of queueing discipline
+TCA_OPTIONS:byte sequence:Qdisc-specific options follow
+TCA_STATS:struct tc_stats:Qdisc statistics
+TCA_XSTATS:qdisc-specific:Module-specific statistics
+TCA_RATE:struct tc_estimator:Rate limit
+.TE
+.IP
+In addition, various other qdisc-module-specific attributes are allowed.
+For more information see the appropriate include files.
+.TP
+.B RTM_NEWTCLASS
+.TQ
+.B RTM_DELTCLASS
+.TQ
+.B RTM_GETTCLASS
+Add, remove, or get a traffic class.
+These messages contain a
+.I struct tcmsg
+as described above.
+.TP
+.B RTM_NEWTFILTER
+.TQ
+.B RTM_DELTFILTER
+.TQ
+.B RTM_GETTFILTER
+Add, remove, or receive information about a traffic filter.
+These messages contain a
+.I struct tcmsg
+as described above.
+.SH VERSIONS
+.B rtnetlink
+is a new feature of Linux 2.2.
+.SH BUGS
+This manual page is incomplete.
+.SH SEE ALSO
+.BR cmsg (3),
+.BR rtnetlink (3),
+.BR ip (7),
+.BR netlink (7)
diff --git a/man/man7/sched.7 b/man/man7/sched.7
new file mode 100644
index 000000000..71f098e48
--- /dev/null
+++ b/man/man7/sched.7
@@ -0,0 +1,992 @@
+.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (C) 2014 Peter Zijlstra <peterz@infradead.org>
+.\" and Copyright (C) 2014 Juri Lelli <juri.lelli@gmail.com>
+.\" Various pieces from the old sched_setscheduler(2) page
+.\" 	Copyright (C) Tom Bjorkholm, Markus Kuhn & David A. Wheeler 1996-1999
+.\" 	and Copyright (C) 2007 Carsten Emde <Carsten.Emde@osadl.org>
+.\" 	and Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Worth looking at: http://rt.wiki.kernel.org/index.php
+.\"
+.TH sched 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sched \- overview of CPU scheduling
+.SH DESCRIPTION
+Since Linux 2.6.23, the default scheduler is CFS,
+the "Completely Fair Scheduler".
+The CFS scheduler replaced the earlier "O(1)" scheduler.
+.\"
+.SS API summary
+Linux provides the following system calls for controlling
+the CPU scheduling behavior, policy, and priority of processes
+(or, more precisely, threads).
+.TP
+.BR nice (2)
+Set a new nice value for the calling thread,
+and return the new nice value.
+.TP
+.BR getpriority (2)
+Return the nice value of a thread, a process group,
+or the set of threads owned by a specified user.
+.TP
+.BR setpriority (2)
+Set the nice value of a thread, a process group,
+or the set of threads owned by a specified user.
+.TP
+.BR sched_setscheduler (2)
+Set the scheduling policy and parameters of a specified thread.
+.TP
+.BR sched_getscheduler (2)
+Return the scheduling policy of a specified thread.
+.TP
+.BR sched_setparam (2)
+Set the scheduling parameters of a specified thread.
+.TP
+.BR sched_getparam (2)
+Fetch the scheduling parameters of a specified thread.
+.TP
+.BR sched_get_priority_max (2)
+Return the maximum priority available in a specified scheduling policy.
+.TP
+.BR sched_get_priority_min (2)
+Return the minimum priority available in a specified scheduling policy.
+.TP
+.BR sched_rr_get_interval (2)
+Fetch the quantum used for threads that are scheduled under
+the "round-robin" scheduling policy.
+.TP
+.BR sched_yield (2)
+Cause the caller to relinquish the CPU,
+so that some other thread be executed.
+.TP
+.BR sched_setaffinity (2)
+(Linux-specific)
+Set the CPU affinity of a specified thread.
+.TP
+.BR sched_getaffinity (2)
+(Linux-specific)
+Get the CPU affinity of a specified thread.
+.TP
+.BR sched_setattr (2)
+Set the scheduling policy and parameters of a specified thread.
+This (Linux-specific) system call provides a superset of the functionality of
+.BR sched_setscheduler (2)
+and
+.BR sched_setparam (2).
+.TP
+.BR sched_getattr (2)
+Fetch the scheduling policy and parameters of a specified thread.
+This (Linux-specific) system call provides a superset of the functionality of
+.BR sched_getscheduler (2)
+and
+.BR sched_getparam (2).
+.\"
+.SS Scheduling policies
+The scheduler is the kernel component that decides which runnable thread
+will be executed by the CPU next.
+Each thread has an associated scheduling policy and a \fIstatic\fP
+scheduling priority,
+.IR sched_priority .
+The scheduler makes its decisions based on knowledge of the scheduling
+policy and static priority of all threads on the system.
+.P
+For threads scheduled under one of the normal scheduling policies
+(\fBSCHED_OTHER\fP, \fBSCHED_IDLE\fP, \fBSCHED_BATCH\fP),
+\fIsched_priority\fP is not used in scheduling
+decisions (it must be specified as 0).
+.P
+Processes scheduled under one of the real-time policies
+(\fBSCHED_FIFO\fP, \fBSCHED_RR\fP) have a
+\fIsched_priority\fP value in the range 1 (low) to 99 (high).
+(As the numbers imply, real-time threads always have higher priority
+than normal threads.)
+Note well: POSIX.1 requires an implementation to support only a
+minimum 32 distinct priority levels for the real-time policies,
+and some systems supply just this minimum.
+Portable programs should use
+.BR sched_get_priority_min (2)
+and
+.BR sched_get_priority_max (2)
+to find the range of priorities supported for a particular policy.
+.P
+Conceptually, the scheduler maintains a list of runnable
+threads for each possible \fIsched_priority\fP value.
+In order to determine which thread runs next, the scheduler looks for
+the nonempty list with the highest static priority and selects the
+thread at the head of this list.
+.P
+A thread's scheduling policy determines
+where it will be inserted into the list of threads
+with equal static priority and how it will move inside this list.
+.P
+All scheduling is preemptive: if a thread with a higher static
+priority becomes ready to run, the currently running thread
+will be preempted and
+returned to the wait list for its static priority level.
+The scheduling policy determines the
+ordering only within the list of runnable threads with equal static
+priority.
+.SS SCHED_FIFO: First in-first out scheduling
+\fBSCHED_FIFO\fP can be used only with static priorities higher than
+0, which means that when a \fBSCHED_FIFO\fP thread becomes runnable,
+it will always immediately preempt any currently running
+\fBSCHED_OTHER\fP, \fBSCHED_BATCH\fP, or \fBSCHED_IDLE\fP thread.
+\fBSCHED_FIFO\fP is a simple scheduling
+algorithm without time slicing.
+For threads scheduled under the
+\fBSCHED_FIFO\fP policy, the following rules apply:
+.IP \[bu] 3
+A running \fBSCHED_FIFO\fP thread that has been preempted by another thread of
+higher priority will stay at the head of the list for its priority and
+will resume execution as soon as all threads of higher priority are
+blocked again.
+.IP \[bu]
+When a blocked \fBSCHED_FIFO\fP thread becomes runnable, it
+will be inserted at the end of the list for its priority.
+.IP \[bu]
+If a call to
+.BR sched_setscheduler (2),
+.BR sched_setparam (2),
+.BR sched_setattr (2),
+.BR pthread_setschedparam (3),
+or
+.BR pthread_setschedprio (3)
+changes the priority of the running or runnable
+.B SCHED_FIFO
+thread identified by
+.I pid
+the effect on the thread's position in the list depends on
+the direction of the change to the thread's priority:
+.RS
+.IP (a) 5
+If the thread's priority is raised,
+it is placed at the end of the list for its new priority.
+As a consequence,
+it may preempt a currently running thread with the same priority.
+.IP (b)
+If the thread's priority is unchanged,
+its position in the run list is unchanged.
+.IP (c)
+If the thread's priority is lowered,
+it is placed at the front of the list for its new priority.
+.RE
+.IP
+According to POSIX.1-2008,
+changes to a thread's priority (or policy) using any mechanism other than
+.BR pthread_setschedprio (3)
+should result in the thread being placed at the end of
+the list for its priority.
+.\" In Linux 2.2.x and Linux 2.4.x, the thread is placed at the front of the queue
+.\" In Linux 2.0.x, the Right Thing happened: the thread went to the back -- MTK
+.IP \[bu]
+A thread calling
+.BR sched_yield (2)
+will be put at the end of the list.
+.P
+No other events will move a thread
+scheduled under the \fBSCHED_FIFO\fP policy in the wait list of
+runnable threads with equal static priority.
+.P
+A \fBSCHED_FIFO\fP
+thread runs until either it is blocked by an I/O request, it is
+preempted by a higher priority thread, or it calls
+.BR sched_yield (2).
+.SS SCHED_RR: Round-robin scheduling
+\fBSCHED_RR\fP is a simple enhancement of \fBSCHED_FIFO\fP.
+Everything
+described above for \fBSCHED_FIFO\fP also applies to \fBSCHED_RR\fP,
+except that each thread is allowed to run only for a maximum time
+quantum.
+If a \fBSCHED_RR\fP thread has been running for a time
+period equal to or longer than the time quantum, it will be put at the
+end of the list for its priority.
+A \fBSCHED_RR\fP thread that has
+been preempted by a higher priority thread and subsequently resumes
+execution as a running thread will complete the unexpired portion of
+its round-robin time quantum.
+The length of the time quantum can be
+retrieved using
+.BR sched_rr_get_interval (2).
+.\" On Linux 2.4, the length of the RR interval is influenced
+.\" by the process nice value -- MTK
+.\"
+.SS SCHED_DEADLINE: Sporadic task model deadline scheduling
+Since Linux 3.14, Linux provides a deadline scheduling policy
+.RB ( SCHED_DEADLINE ).
+This policy is currently implemented using
+GEDF (Global Earliest Deadline First)
+in conjunction with CBS (Constant Bandwidth Server).
+To set and fetch this policy and associated attributes,
+one must use the Linux-specific
+.BR sched_setattr (2)
+and
+.BR sched_getattr (2)
+system calls.
+.P
+A sporadic task is one that has a sequence of jobs, where each
+job is activated at most once per period.
+Each job also has a
+.IR "relative deadline" ,
+before which it should finish execution, and a
+.IR "computation time" ,
+which is the CPU time necessary for executing the job.
+The moment when a task wakes up
+because a new job has to be executed is called the
+.I arrival time
+(also referred to as the request time or release time).
+The
+.I start time
+is the time at which a task starts its execution.
+The
+.I absolute deadline
+is thus obtained by adding the relative deadline to the arrival time.
+.P
+The following diagram clarifies these terms:
+.P
+.in +4n
+.EX
+arrival/wakeup                    absolute deadline
+     |    start time                    |
+     |        |                         |
+     v        v                         v
+-----x--------xooooooooooooooooo--------x--------x---
+              |<- comp. time ->|
+     |<------- relative deadline ------>|
+     |<-------------- period ------------------->|
+.EE
+.in
+.P
+When setting a
+.B SCHED_DEADLINE
+policy for a thread using
+.BR sched_setattr (2),
+one can specify three parameters:
+.IR Runtime ,
+.IR Deadline ,
+and
+.IR Period .
+These parameters do not necessarily correspond to the aforementioned terms:
+usual practice is to set Runtime to something bigger than the average
+computation time (or worst-case execution time for hard real-time tasks),
+Deadline to the relative deadline, and Period to the period of the task.
+Thus, for
+.B SCHED_DEADLINE
+scheduling, we have:
+.P
+.in +4n
+.EX
+arrival/wakeup                    absolute deadline
+     |    start time                    |
+     |        |                         |
+     v        v                         v
+-----x--------xooooooooooooooooo--------x--------x---
+              |<-- Runtime ------->|
+     |<----------- Deadline ----------->|
+     |<-------------- Period ------------------->|
+.EE
+.in
+.P
+The three deadline-scheduling parameters correspond to the
+.IR sched_runtime ,
+.IR sched_deadline ,
+and
+.I sched_period
+fields of the
+.I sched_attr
+structure; see
+.BR sched_setattr (2).
+These fields express values in nanoseconds.
+.\" FIXME It looks as though specifying sched_period as 0 means
+.\" "make sched_period the same as sched_deadline".
+.\" This needs to be documented.
+If
+.I sched_period
+is specified as 0, then it is made the same as
+.IR sched_deadline .
+.P
+The kernel requires that:
+.P
+.in +4n
+.EX
+sched_runtime <= sched_deadline <= sched_period
+.EE
+.in
+.P
+.\" See __checkparam_dl in kernel/sched/core.c
+In addition, under the current implementation,
+all of the parameter values must be at least 1024
+(i.e., just over one microsecond,
+which is the resolution of the implementation), and less than 2\[ha]63.
+If any of these checks fails,
+.BR sched_setattr (2)
+fails with the error
+.BR EINVAL .
+.P
+The CBS guarantees non-interference between tasks, by throttling
+threads that attempt to over-run their specified Runtime.
+.P
+To ensure deadline scheduling guarantees,
+the kernel must prevent situations where the set of
+.B SCHED_DEADLINE
+threads is not feasible (schedulable) within the given constraints.
+The kernel thus performs an admittance test when setting or changing
+.B SCHED_DEADLINE
+policy and attributes.
+This admission test calculates whether the change is feasible;
+if it is not,
+.BR sched_setattr (2)
+fails with the error
+.BR EBUSY .
+.P
+For example, it is required (but not necessarily sufficient) for
+the total utilization to be less than or equal to the total number of
+CPUs available, where, since each thread can maximally run for
+Runtime per Period, that thread's utilization is its
+Runtime divided by its Period.
+.P
+In order to fulfill the guarantees that are made when
+a thread is admitted to the
+.B SCHED_DEADLINE
+policy,
+.B SCHED_DEADLINE
+threads are the highest priority (user controllable) threads in the
+system; if any
+.B SCHED_DEADLINE
+thread is runnable,
+it will preempt any thread scheduled under one of the other policies.
+.P
+A call to
+.BR fork (2)
+by a thread scheduled under the
+.B SCHED_DEADLINE
+policy fails with the error
+.BR EAGAIN ,
+unless the thread has its reset-on-fork flag set (see below).
+.P
+A
+.B SCHED_DEADLINE
+thread that calls
+.BR sched_yield (2)
+will yield the current job and wait for a new period to begin.
+.\"
+.\" FIXME Calling sched_getparam() on a SCHED_DEADLINE thread
+.\" fails with EINVAL, but sched_getscheduler() succeeds.
+.\" Is that intended? (Why?)
+.\"
+.SS SCHED_OTHER: Default Linux time-sharing scheduling
+\fBSCHED_OTHER\fP can be used at only static priority 0
+(i.e., threads under real-time policies always have priority over
+.B SCHED_OTHER
+processes).
+\fBSCHED_OTHER\fP is the standard Linux time-sharing scheduler that is
+intended for all threads that do not require the special
+real-time mechanisms.
+.P
+The thread to run is chosen from the static
+priority 0 list based on a \fIdynamic\fP priority that is determined only
+inside this list.
+The dynamic priority is based on the nice value (see below)
+and is increased for each time quantum the thread is ready to run,
+but denied to run by the scheduler.
+This ensures fair progress among all \fBSCHED_OTHER\fP threads.
+.P
+In the Linux kernel source code, the
+.B SCHED_OTHER
+policy is actually named
+.BR SCHED_NORMAL .
+.\"
+.SS The nice value
+The nice value is an attribute
+that can be used to influence the CPU scheduler to
+favor or disfavor a process in scheduling decisions.
+It affects the scheduling of
+.B SCHED_OTHER
+and
+.B SCHED_BATCH
+(see below) processes.
+The nice value can be modified using
+.BR nice (2),
+.BR setpriority (2),
+or
+.BR sched_setattr (2).
+.P
+According to POSIX.1, the nice value is a per-process attribute;
+that is, the threads in a process should share a nice value.
+However, on Linux, the nice value is a per-thread attribute:
+different threads in the same process may have different nice values.
+.P
+The range of the nice value
+varies across UNIX systems.
+On modern Linux, the range is \-20 (high priority) to +19 (low priority).
+On some other systems, the range is \-20..20.
+Very early Linux kernels (before Linux 2.0) had the range \-infinity..15.
+.\" Linux before 1.3.36 had \-infinity..15.
+.\" Since Linux 1.3.43, Linux has the range \-20..19.
+.P
+The degree to which the nice value affects the relative scheduling of
+.B SCHED_OTHER
+processes likewise varies across UNIX systems and
+across Linux kernel versions.
+.P
+With the advent of the CFS scheduler in Linux 2.6.23,
+Linux adopted an algorithm that causes
+relative differences in nice values to have a much stronger effect.
+In the current implementation, each unit of difference in the
+nice values of two processes results in a factor of 1.25
+in the degree to which the scheduler favors the higher priority process.
+This causes very low nice values (+19) to truly provide little CPU
+to a process whenever there is any other
+higher priority load on the system,
+and makes high nice values (\-20) deliver most of the CPU to applications
+that require it (e.g., some audio applications).
+.P
+On Linux, the
+.B RLIMIT_NICE
+resource limit can be used to define a limit to which
+an unprivileged process's nice value can be raised; see
+.BR setrlimit (2)
+for details.
+.P
+For further details on the nice value, see the subsections on
+the autogroup feature and group scheduling, below.
+.\"
+.SS SCHED_BATCH: Scheduling batch processes
+(Since Linux 2.6.16.)
+\fBSCHED_BATCH\fP can be used only at static priority 0.
+This policy is similar to \fBSCHED_OTHER\fP in that it schedules
+the thread according to its dynamic priority
+(based on the nice value).
+The difference is that this policy
+will cause the scheduler to always assume
+that the thread is CPU-intensive.
+Consequently, the scheduler will apply a small scheduling
+penalty with respect to wakeup behavior,
+so that this thread is mildly disfavored in scheduling decisions.
+.P
+.\" The following paragraph is drawn largely from the text that
+.\" accompanied Ingo Molnar's patch for the implementation of
+.\" SCHED_BATCH.
+.\" commit b0a9499c3dd50d333e2aedb7e894873c58da3785
+This policy is useful for workloads that are noninteractive,
+but do not want to lower their nice value,
+and for workloads that want a deterministic scheduling policy without
+interactivity causing extra preemptions (between the workload's tasks).
+.\"
+.SS SCHED_IDLE: Scheduling very low priority jobs
+(Since Linux 2.6.23.)
+\fBSCHED_IDLE\fP can be used only at static priority 0;
+the process nice value has no influence for this policy.
+.P
+This policy is intended for running jobs at extremely low
+priority (lower even than a +19 nice value with the
+.B SCHED_OTHER
+or
+.B SCHED_BATCH
+policies).
+.\"
+.SS Resetting scheduling policy for child processes
+Each thread has a reset-on-fork scheduling flag.
+When this flag is set, children created by
+.BR fork (2)
+do not inherit privileged scheduling policies.
+The reset-on-fork flag can be set by either:
+.IP \[bu] 3
+ORing the
+.B SCHED_RESET_ON_FORK
+flag into the
+.I policy
+argument when calling
+.BR sched_setscheduler (2)
+(since Linux 2.6.32);
+or
+.IP \[bu]
+specifying the
+.B SCHED_FLAG_RESET_ON_FORK
+flag in
+.I attr.sched_flags
+when calling
+.BR sched_setattr (2).
+.P
+Note that the constants used with these two APIs have different names.
+The state of the reset-on-fork flag can analogously be retrieved using
+.BR sched_getscheduler (2)
+and
+.BR sched_getattr (2).
+.P
+The reset-on-fork feature is intended for media-playback applications,
+and can be used to prevent applications evading the
+.B RLIMIT_RTTIME
+resource limit (see
+.BR getrlimit (2))
+by creating multiple child processes.
+.P
+More precisely, if the reset-on-fork flag is set,
+the following rules apply for subsequently created children:
+.IP \[bu] 3
+If the calling thread has a scheduling policy of
+.B SCHED_FIFO
+or
+.BR SCHED_RR ,
+the policy is reset to
+.B SCHED_OTHER
+in child processes.
+.IP \[bu]
+If the calling process has a negative nice value,
+the nice value is reset to zero in child processes.
+.P
+After the reset-on-fork flag has been enabled,
+it can be reset only if the thread has the
+.B CAP_SYS_NICE
+capability.
+This flag is disabled in child processes created by
+.BR fork (2).
+.\"
+.SS Privileges and resource limits
+Before Linux 2.6.12, only privileged
+.RB ( CAP_SYS_NICE )
+threads can set a nonzero static priority (i.e., set a real-time
+scheduling policy).
+The only change that an unprivileged thread can make is to set the
+.B SCHED_OTHER
+policy, and this can be done only if the effective user ID of the caller
+matches the real or effective user ID of the target thread
+(i.e., the thread specified by
+.IR pid )
+whose policy is being changed.
+.P
+A thread must be privileged
+.RB ( CAP_SYS_NICE )
+in order to set or modify a
+.B SCHED_DEADLINE
+policy.
+.P
+Since Linux 2.6.12, the
+.B RLIMIT_RTPRIO
+resource limit defines a ceiling on an unprivileged thread's
+static priority for the
+.B SCHED_RR
+and
+.B SCHED_FIFO
+policies.
+The rules for changing scheduling policy and priority are as follows:
+.IP \[bu] 3
+If an unprivileged thread has a nonzero
+.B RLIMIT_RTPRIO
+soft limit, then it can change its scheduling policy and priority,
+subject to the restriction that the priority cannot be set to a
+value higher than the maximum of its current priority and its
+.B RLIMIT_RTPRIO
+soft limit.
+.IP \[bu]
+If the
+.B RLIMIT_RTPRIO
+soft limit is 0, then the only permitted changes are to lower the priority,
+or to switch to a non-real-time policy.
+.IP \[bu]
+Subject to the same rules,
+another unprivileged thread can also make these changes,
+as long as the effective user ID of the thread making the change
+matches the real or effective user ID of the target thread.
+.IP \[bu]
+Special rules apply for the
+.B SCHED_IDLE
+policy.
+Before Linux 2.6.39,
+an unprivileged thread operating under this policy cannot
+change its policy, regardless of the value of its
+.B RLIMIT_RTPRIO
+resource limit.
+Since Linux 2.6.39,
+.\" commit c02aa73b1d18e43cfd79c2f193b225e84ca497c8
+an unprivileged thread can switch to either the
+.B SCHED_BATCH
+or the
+.B SCHED_OTHER
+policy so long as its nice value falls within the range permitted by its
+.B RLIMIT_NICE
+resource limit (see
+.BR getrlimit (2)).
+.P
+Privileged
+.RB ( CAP_SYS_NICE )
+threads ignore the
+.B RLIMIT_RTPRIO
+limit; as with older kernels,
+they can make arbitrary changes to scheduling policy and priority.
+See
+.BR getrlimit (2)
+for further information on
+.BR RLIMIT_RTPRIO .
+.SS Limiting the CPU usage of real-time and deadline processes
+A nonblocking infinite loop in a thread scheduled under the
+.BR SCHED_FIFO ,
+.BR SCHED_RR ,
+or
+.B SCHED_DEADLINE
+policy can potentially block all other threads from accessing
+the CPU forever.
+Before Linux 2.6.25, the only way of preventing a runaway real-time
+process from freezing the system was to run (at the console)
+a shell scheduled under a higher static priority than the tested application.
+This allows an emergency kill of tested
+real-time applications that do not block or terminate as expected.
+.P
+Since Linux 2.6.25, there are other techniques for dealing with runaway
+real-time and deadline processes.
+One of these is to use the
+.B RLIMIT_RTTIME
+resource limit to set a ceiling on the CPU time that
+a real-time process may consume.
+See
+.BR getrlimit (2)
+for details.
+.P
+Since Linux 2.6.25, Linux also provides two
+.I /proc
+files that can be used to reserve a certain amount of CPU time
+to be used by non-real-time processes.
+Reserving CPU time in this fashion allows some CPU time to be
+allocated to (say) a root shell that can be used to kill a runaway process.
+Both of these files specify time values in microseconds:
+.TP
+.I /proc/sys/kernel/sched_rt_period_us
+This file specifies a scheduling period that is equivalent to
+100% CPU bandwidth.
+The value in this file can range from 1 to
+.BR INT_MAX ,
+giving an operating range of 1 microsecond to around 35 minutes.
+The default value in this file is 1,000,000 (1 second).
+.TP
+.I /proc/sys/kernel/sched_rt_runtime_us
+The value in this file specifies how much of the "period" time
+can be used by all real-time and deadline scheduled processes
+on the system.
+The value in this file can range from \-1 to
+.BR INT_MAX \-1.
+Specifying \-1 makes the run time the same as the period;
+that is, no CPU time is set aside for non-real-time processes
+(which was the behavior before Linux 2.6.25).
+The default value in this file is 950,000 (0.95 seconds),
+meaning that 5% of the CPU time is reserved for processes that
+don't run under a real-time or deadline scheduling policy.
+.SS Response time
+A blocked high priority thread waiting for I/O has a certain
+response time before it is scheduled again.
+The device driver writer
+can greatly reduce this response time by using a "slow interrupt"
+interrupt handler.
+.\" as described in
+.\" .BR request_irq (9).
+.SS Miscellaneous
+Child processes inherit the scheduling policy and parameters across a
+.BR fork (2).
+The scheduling policy and parameters are preserved across
+.BR execve (2).
+.P
+Memory locking is usually needed for real-time processes to avoid
+paging delays; this can be done with
+.BR mlock (2)
+or
+.BR mlockall (2).
+.\"
+.SS The autogroup feature
+.\" commit 5091faa449ee0b7d73bc296a93bca9540fc51d0a
+Since Linux 2.6.38,
+the kernel provides a feature known as autogrouping to improve interactive
+desktop performance in the face of multiprocess, CPU-intensive
+workloads such as building the Linux kernel with large numbers of
+parallel build processes (i.e., the
+.BR make (1)
+.B \-j
+flag).
+.P
+This feature operates in conjunction with the
+CFS scheduler and requires a kernel that is configured with
+.BR CONFIG_SCHED_AUTOGROUP .
+On a running system, this feature is enabled or disabled via the file
+.IR /proc/sys/kernel/sched_autogroup_enabled ;
+a value of 0 disables the feature, while a value of 1 enables it.
+The default value in this file is 1, unless the kernel was booted with the
+.I noautogroup
+parameter.
+.P
+A new autogroup is created when a new session is created via
+.BR setsid (2);
+this happens, for example, when a new terminal window is started.
+A new process created by
+.BR fork (2)
+inherits its parent's autogroup membership.
+Thus, all of the processes in a session are members of the same autogroup.
+An autogroup is automatically destroyed when the last process
+in the group terminates.
+.P
+When autogrouping is enabled, all of the members of an autogroup
+are placed in the same kernel scheduler "task group".
+The CFS scheduler employs an algorithm that equalizes the
+distribution of CPU cycles across task groups.
+The benefits of this for interactive desktop performance
+can be described via the following example.
+.P
+Suppose that there are two autogroups competing for the same CPU
+(i.e., presume either a single CPU system or the use of
+.BR taskset (1)
+to confine all the processes to the same CPU on an SMP system).
+The first group contains ten CPU-bound processes from
+a kernel build started with
+.IR "make\~\-j10" .
+The other contains a single CPU-bound process: a video player.
+The effect of autogrouping is that the two groups will
+each receive half of the CPU cycles.
+That is, the video player will receive 50% of the CPU cycles,
+rather than just 9% of the cycles,
+which would likely lead to degraded video playback.
+The situation on an SMP system is more complex,
+.\" Mike Galbraith, 25 Nov 2016:
+.\"     I'd say something more wishy-washy here, like cycles are
+.\"     distributed fairly across groups and leave it at that, as your
+.\"     detailed example is incorrect due to SMP fairness (which I don't
+.\"     like much because [very unlikely] worst case scenario
+.\"     renders a box sized group incapable of utilizing more that
+.\"     a single CPU total).  For example, if a group of NR_CPUS
+.\"     size competes with a singleton, load balancing will try to give
+.\"     the singleton a full CPU of its very own.  If groups intersect for
+.\"     whatever reason on say my quad lappy, distribution is 80/20 in
+.\"     favor of the singleton.
+but the general effect is the same:
+the scheduler distributes CPU cycles across task groups such that
+an autogroup that contains a large number of CPU-bound processes
+does not end up hogging CPU cycles at the expense of the other
+jobs on the system.
+.P
+A process's autogroup (task group) membership can be viewed via the file
+.IR /proc/ pid /autogroup :
+.P
+.in +4n
+.EX
+$ \fBcat /proc/1/autogroup\fP
+/autogroup\-1 nice 0
+.EE
+.in
+.P
+This file can also be used to modify the CPU bandwidth allocated
+to an autogroup.
+This is done by writing a number in the "nice" range to the file
+to set the autogroup's nice value.
+The allowed range is from +19 (low priority) to \-20 (high priority).
+(Writing values outside of this range causes
+.BR write (2)
+to fail with the error
+.BR EINVAL .)
+.\" FIXME .
+.\" Because of a bug introduced in Linux 4.7
+.\" (commit 2159197d66770ec01f75c93fb11dc66df81fd45b made changes
+.\" that exposed the fact that autogroup didn't call scale_load()),
+.\" it happened that *all* values in this range caused a task group
+.\" to be further disfavored by the scheduler, with \-20 resulting
+.\" in the scheduler mildly disfavoring the task group and +19 greatly
+.\" disfavoring it.
+.\"
+.\" A patch was posted on 23 Nov 2016
+.\" ("sched/autogroup: Fix 64bit kernel nice adjustment";
+.\" check later to see in which kernel version it lands.
+.P
+The autogroup nice setting has the same meaning as the process nice value,
+but applies to distribution of CPU cycles to the autogroup as a whole,
+based on the relative nice values of other autogroups.
+For a process inside an autogroup, the CPU cycles that it receives
+will be a product of the autogroup's nice value
+(compared to other autogroups)
+and the process's nice value
+(compared to other processes in the same autogroup.
+.P
+The use of the
+.BR cgroups (7)
+CPU controller to place processes in cgroups other than the
+root CPU cgroup overrides the effect of autogrouping.
+.P
+The autogroup feature groups only processes scheduled under
+non-real-time policies
+.RB ( SCHED_OTHER ,
+.BR SCHED_BATCH ,
+and
+.BR SCHED_IDLE ).
+It does not group processes scheduled under real-time and
+deadline policies.
+Those processes are scheduled according to the rules described earlier.
+.\"
+.SS The nice value and group scheduling
+When scheduling non-real-time processes (i.e., those scheduled under the
+.BR SCHED_OTHER ,
+.BR SCHED_BATCH ,
+and
+.B SCHED_IDLE
+policies), the CFS scheduler employs a technique known as "group scheduling",
+if the kernel was configured with the
+.B CONFIG_FAIR_GROUP_SCHED
+option (which is typical).
+.P
+Under group scheduling, threads are scheduled in "task groups".
+Task groups have a hierarchical relationship,
+rooted under the initial task group on the system,
+known as the "root task group".
+Task groups are formed in the following circumstances:
+.IP \[bu] 3
+All of the threads in a CPU cgroup form a task group.
+The parent of this task group is the task group of the
+corresponding parent cgroup.
+.IP \[bu]
+If autogrouping is enabled,
+then all of the threads that are (implicitly) placed in an autogroup
+(i.e., the same session, as created by
+.BR setsid (2))
+form a task group.
+Each new autogroup is thus a separate task group.
+The root task group is the parent of all such autogroups.
+.IP \[bu]
+If autogrouping is enabled, then the root task group consists of
+all processes in the root CPU cgroup that were not
+otherwise implicitly placed into a new autogroup.
+.IP \[bu]
+If autogrouping is disabled, then the root task group consists of
+all processes in the root CPU cgroup.
+.IP \[bu]
+If group scheduling was disabled (i.e., the kernel was configured without
+.BR CONFIG_FAIR_GROUP_SCHED ),
+then all of the processes on the system are notionally placed
+in a single task group.
+.P
+Under group scheduling,
+a thread's nice value has an effect for scheduling decisions
+.IR "only relative to other threads in the same task group" .
+This has some surprising consequences in terms of the traditional semantics
+of the nice value on UNIX systems.
+In particular, if autogrouping
+is enabled (which is the default in various distributions), then employing
+.BR setpriority (2)
+or
+.BR nice (1)
+on a process has an effect only for scheduling relative
+to other processes executed in the same session
+(typically: the same terminal window).
+.P
+Conversely, for two processes that are (for example)
+the sole CPU-bound processes in different sessions
+(e.g., different terminal windows,
+each of whose jobs are tied to different autogroups),
+.I modifying the nice value of the process in one of the sessions
+.I has no effect
+in terms of the scheduler's decisions relative to the
+process in the other session.
+.\" More succinctly: the nice(1) command is in many cases a no-op since
+.\" Linux 2.6.38.
+.\"
+A possibly useful workaround here is to use a command such as
+the following to modify the autogroup nice value for
+.I all
+of the processes in a terminal session:
+.P
+.in +4n
+.EX
+$ \fBecho 10 > /proc/self/autogroup\fP
+.EE
+.in
+.SS Real-time features in the mainline Linux kernel
+.\" FIXME . Probably this text will need some minor tweaking
+.\" ask Carsten Emde about this.
+Since Linux 2.6.18, Linux is gradually
+becoming equipped with real-time capabilities,
+most of which are derived from the former
+.I realtime\-preempt
+patch set.
+Until the patches have been completely merged into the
+mainline kernel,
+they must be installed to achieve the best real-time performance.
+These patches are named:
+.P
+.in +4n
+.EX
+patch\-\fIkernelversion\fP\-rt\fIpatchversion\fP
+.EE
+.in
+.P
+and can be downloaded from
+.UR http://www.kernel.org\:/pub\:/linux\:/kernel\:/projects\:/rt/
+.UE .
+.P
+Without the patches and prior to their full inclusion into the mainline
+kernel, the kernel configuration offers only the three preemption classes
+.BR CONFIG_PREEMPT_NONE ,
+.BR CONFIG_PREEMPT_VOLUNTARY ,
+and
+.B CONFIG_PREEMPT_DESKTOP
+which respectively provide no, some, and considerable
+reduction of the worst-case scheduling latency.
+.P
+With the patches applied or after their full inclusion into the mainline
+kernel, the additional configuration item
+.B CONFIG_PREEMPT_RT
+becomes available.
+If this is selected, Linux is transformed into a regular
+real-time operating system.
+The FIFO and RR scheduling policies are then used to run a thread
+with true real-time priority and a minimum worst-case scheduling latency.
+.SH NOTES
+The
+.BR cgroups (7)
+CPU controller can be used to limit the CPU consumption of
+groups of processes.
+.P
+Originally, Standard Linux was intended as a general-purpose operating
+system being able to handle background processes, interactive
+applications, and less demanding real-time applications (applications that
+need to usually meet timing deadlines).
+Although the Linux 2.6
+allowed for kernel preemption and the newly introduced O(1) scheduler
+ensures that the time needed to schedule is fixed and deterministic
+irrespective of the number of active tasks, true real-time computing
+was not possible up to Linux 2.6.17.
+.SH SEE ALSO
+.ad l
+.nh
+.BR chcpu (1),
+.BR chrt (1),
+.BR lscpu (1),
+.BR ps (1),
+.BR taskset (1),
+.BR top (1),
+.BR getpriority (2),
+.BR mlock (2),
+.BR mlockall (2),
+.BR munlock (2),
+.BR munlockall (2),
+.BR nice (2),
+.BR sched_get_priority_max (2),
+.BR sched_get_priority_min (2),
+.BR sched_getaffinity (2),
+.BR sched_getparam (2),
+.BR sched_getscheduler (2),
+.BR sched_rr_get_interval (2),
+.BR sched_setaffinity (2),
+.BR sched_setparam (2),
+.BR sched_setscheduler (2),
+.BR sched_yield (2),
+.BR setpriority (2),
+.BR pthread_getaffinity_np (3),
+.BR pthread_getschedparam (3),
+.BR pthread_setaffinity_np (3),
+.BR sched_getcpu (3),
+.BR capabilities (7),
+.BR cpuset (7)
+.ad
+.P
+.I Programming for the real world \- POSIX.4
+by Bill O.\& Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0.
+.P
+The Linux kernel source files
+.IR \%Documentation/\:scheduler/\:sched\-deadline\:.txt ,
+.IR \%Documentation/\:scheduler/\:sched\-rt\-group\:.txt ,
+.IR \%Documentation/\:scheduler/\:sched\-design\-CFS\:.txt ,
+and
+.I \%Documentation/\:scheduler/\:sched\-nice\-design\:.txt
diff --git a/man/man7/sem_overview.7 b/man/man7/sem_overview.7
new file mode 100644
index 000000000..fb9ff1535
--- /dev/null
+++ b/man/man7/sem_overview.7
@@ -0,0 +1,139 @@
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_overview 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_overview \- overview of POSIX semaphores
+.SH DESCRIPTION
+POSIX semaphores allow processes and threads to synchronize their actions.
+.P
+A semaphore is an integer whose value is never allowed to fall below zero.
+Two operations can be performed on semaphores:
+increment the semaphore value by one
+.RB ( sem_post (3));
+and decrement the semaphore value by one
+.RB ( sem_wait (3)).
+If the value of a semaphore is currently zero, then a
+.BR sem_wait (3)
+operation will block until the value becomes greater than zero.
+.P
+POSIX semaphores come in two forms: named semaphores and
+unnamed semaphores.
+.TP
+.B Named semaphores
+A named semaphore is identified by a name of the form
+.IR /somename ;
+that is, a null-terminated string of up to
+.BI NAME_MAX \-4
+(i.e., 251) characters consisting of an initial slash,
+.\" glibc allows the initial slash to be omitted, and makes
+.\" multiple initial slashes equivalent to a single slash.
+.\" This differs from the implementation of POSIX message queues.
+followed by one or more characters, none of which are slashes.
+.\" glibc allows subdirectory components in the name, in which
+.\" case the subdirectory tree must exist under /dev/shm, and
+.\" the fist subdirectory component must exist as the name
+.\" sem.name, and all of the subdirectory components must allow the
+.\" required permissions if a user wants to create a semaphore
+.\" object in a subdirectory.
+Two processes can operate on the same named semaphore by passing
+the same name to
+.BR sem_open (3).
+.IP
+The
+.BR sem_open (3)
+function creates a new named semaphore or opens an existing
+named semaphore.
+After the semaphore has been opened, it can be operated on using
+.BR sem_post (3)
+and
+.BR sem_wait (3).
+When a process has finished using the semaphore, it can use
+.BR sem_close (3)
+to close the semaphore.
+When all processes have finished using the semaphore,
+it can be removed from the system using
+.BR sem_unlink (3).
+.TP
+.B Unnamed semaphores (memory-based semaphores)
+An unnamed semaphore does not have a name.
+Instead the semaphore is placed in a region of memory that
+is shared between multiple threads (a
+.IR "thread-shared semaphore" )
+or processes (a
+.IR "process-shared semaphore" ).
+A thread-shared semaphore is placed in an area of memory shared
+between the threads of a process, for example, a global variable.
+A process-shared semaphore must be placed in a shared memory region
+(e.g., a System V shared memory segment created using
+.BR shmget (2),
+or a POSIX shared memory object built created using
+.BR shm_open (3)).
+.IP
+Before being used, an unnamed semaphore must be initialized using
+.BR sem_init (3).
+It can then be operated on using
+.BR sem_post (3)
+and
+.BR sem_wait (3).
+When the semaphore is no longer required,
+and before the memory in which it is located is deallocated,
+the semaphore should be destroyed using
+.BR sem_destroy (3).
+.P
+The remainder of this section describes some specific details
+of the Linux implementation of POSIX semaphores.
+.SS Versions
+Before Linux 2.6, Linux supported only unnamed,
+thread-shared semaphores.
+On a system with Linux 2.6 and a glibc that provides the NPTL
+threading implementation,
+a complete implementation of POSIX semaphores is provided.
+.SS Persistence
+POSIX named semaphores have kernel persistence:
+if not removed by
+.BR sem_unlink (3),
+a semaphore will exist until the system is shut down.
+.SS Linking
+Programs using the POSIX semaphores API must be compiled with
+.I cc \-pthread
+to link against the real-time library,
+.IR librt .
+.SS Accessing named semaphores via the filesystem
+On Linux, named semaphores are created in a virtual filesystem,
+normally mounted under
+.IR /dev/shm ,
+with names of the form
+.IR \fBsem.\fPsomename .
+(This is the reason that semaphore names are limited to
+.BI NAME_MAX \-4
+rather than
+.B NAME_MAX
+characters.)
+.P
+Since Linux 2.6.19, ACLs can be placed on files under this directory,
+to control object permissions on a per-user and per-group basis.
+.SH NOTES
+System V semaphores
+.RB ( semget (2),
+.BR semop (2),
+etc.) are an older semaphore API.
+POSIX semaphores provide a simpler, and better designed interface than
+System V semaphores;
+on the other hand POSIX semaphores are less widely available
+(especially on older systems) than System V semaphores.
+.SH EXAMPLES
+An example of the use of various POSIX semaphore functions is shown in
+.BR sem_wait (3).
+.SH SEE ALSO
+.BR sem_close (3),
+.BR sem_destroy (3),
+.BR sem_getvalue (3),
+.BR sem_init (3),
+.BR sem_open (3),
+.BR sem_post (3),
+.BR sem_unlink (3),
+.BR sem_wait (3),
+.BR pthreads (7),
+.BR shm_overview (7)
diff --git a/man/man7/session-keyring.7 b/man/man7/session-keyring.7
new file mode 100644
index 000000000..d54007ee1
--- /dev/null
+++ b/man/man7/session-keyring.7
@@ -0,0 +1,113 @@
+.\" Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH session-keyring 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+session-keyring \- session shared process keyring
+.SH DESCRIPTION
+The session keyring is a keyring used to anchor keys on behalf of a process.
+It is typically created by
+.BR pam_keyinit (8)
+when a user logs in and a link will be added that refers to the
+.BR user\-keyring (7).
+Optionally,
+.BR PAM (7)
+may revoke the session keyring on logout.
+(In typical configurations, PAM does do this revocation.)
+The session keyring has the name (description)
+.IR _ses .
+.P
+A special serial number value,
+.BR KEY_SPEC_SESSION_KEYRING ,
+is defined that can be used in lieu of the actual serial number of
+the calling process's session keyring.
+.P
+From the
+.BR keyctl (1)
+utility, '\fB@s\fP' can be used instead of a numeric key ID in
+much the same way.
+.P
+A process's session keyring is inherited across
+.BR clone (2),
+.BR fork (2),
+and
+.BR vfork (2).
+The session keyring
+is preserved across
+.BR execve (2),
+even when the executable is set-user-ID or set-group-ID or has capabilities.
+The session keyring is destroyed when the last process that
+refers to it exits.
+.P
+If a process doesn't have a session keyring when it is accessed, then,
+under certain circumstances, the
+.BR user\-session\-keyring (7)
+will be attached as the session keyring
+and under others a new session keyring will be created.
+(See
+.BR user\-session\-keyring (7)
+for further details.)
+.SS Special operations
+The
+.I keyutils
+library provides the following special operations for manipulating
+session keyrings:
+.TP
+.BR keyctl_join_session_keyring (3)
+This operation allows the caller to change the session keyring
+that it subscribes to.
+The caller can join an existing keyring with a specified name (description),
+create a new keyring with a given name,
+or ask the kernel to create a new "anonymous"
+session keyring with the name "_ses".
+(This function is an interface to the
+.BR keyctl (2)
+.B KEYCTL_JOIN_SESSION_KEYRING
+operation.)
+.TP
+.BR keyctl_session_to_parent (3)
+This operation allows the caller to make the parent process's
+session keyring to the same as its own.
+For this to succeed, the parent process must have
+identical security attributes and must be single threaded.
+(This function is an interface to the
+.BR keyctl (2)
+.B KEYCTL_SESSION_TO_PARENT
+operation.)
+.P
+These operations are also exposed through the
+.BR keyctl (1)
+utility as:
+.P
+.in +4n
+.EX
+keyctl session
+keyctl session \- [<prog> <arg1> <arg2> ...]
+keyctl session <name> [<prog> <arg1> <arg2> ...]
+.EE
+.in
+.P
+and:
+.P
+.in +4n
+.EX
+keyctl new_session
+.EE
+.in
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR keyctl (3),
+.BR keyctl_join_session_keyring (3),
+.BR keyctl_session_to_parent (3),
+.BR keyrings (7),
+.BR PAM (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7),
+.BR user\-session\-keyring (7),
+.BR pam_keyinit (8)
diff --git a/man/man7/shm_overview.7 b/man/man7/shm_overview.7
new file mode 100644
index 000000000..85fbce2a0
--- /dev/null
+++ b/man/man7/shm_overview.7
@@ -0,0 +1,104 @@
+.\" Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk
+.\" <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH shm_overview 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+shm_overview \- overview of POSIX shared memory
+.SH DESCRIPTION
+The POSIX shared memory API allows processes to communicate information
+by sharing a region of memory.
+.P
+The interfaces employed in the API are:
+.TP 15
+.BR shm_open (3)
+Create and open a new object, or open an existing object.
+This is analogous to
+.BR open (2).
+The call returns a file descriptor for use by the other
+interfaces listed below.
+.TP
+.BR ftruncate (2)
+Set the size of the shared memory object.
+(A newly created shared memory object has a length of zero.)
+.TP
+.BR mmap (2)
+Map the shared memory object into the virtual address space
+of the calling process.
+.TP
+.BR munmap (2)
+Unmap the shared memory object from the virtual address space
+of the calling process.
+.TP
+.BR shm_unlink (3)
+Remove a shared memory object name.
+.TP
+.BR close (2)
+Close the file descriptor allocated by
+.BR shm_open (3)
+when it is no longer needed.
+.TP
+.BR fstat (2)
+Obtain a
+.I stat
+structure that describes the shared memory object.
+Among the information returned by this call are the object's
+size
+.RI ( st_size ),
+permissions
+.RI ( st_mode ),
+owner
+.RI ( st_uid ),
+and group
+.RI ( st_gid ).
+.TP
+.BR fchown (2)
+To change the ownership of a shared memory object.
+.TP
+.BR fchmod (2)
+To change the permissions of a shared memory object.
+.SS Versions
+POSIX shared memory is supported since Linux 2.4 and glibc 2.2.
+.SS Persistence
+POSIX shared memory objects have kernel persistence:
+a shared memory object will exist until the system is shut down,
+or until all processes have unmapped the object and it has been deleted with
+.BR shm_unlink (3)
+.SS Linking
+Programs using the POSIX shared memory API must be compiled with
+.I cc \-lrt
+to link against the real-time library,
+.IR librt .
+.SS Accessing shared memory objects via the filesystem
+On Linux, shared memory objects are created in a
+.RB ( tmpfs (5))
+virtual filesystem, normally mounted under
+.IR /dev/shm .
+Since Linux 2.6.19, Linux supports the use of access control lists (ACLs)
+to control the permissions of objects in the virtual filesystem.
+.SH NOTES
+Typically, processes must synchronize their access to a shared
+memory object, using, for example, POSIX semaphores.
+.P
+System V shared memory
+.RB ( shmget (2),
+.BR shmop (2),
+etc.) is an older shared memory API.
+POSIX shared memory provides a simpler, and better designed interface;
+on the other hand POSIX shared memory is somewhat less widely available
+(especially on older systems) than System V shared memory.
+.SH SEE ALSO
+.BR fchmod (2),
+.BR fchown (2),
+.BR fstat (2),
+.BR ftruncate (2),
+.BR memfd_create (2),
+.BR mmap (2),
+.BR mprotect (2),
+.BR munmap (2),
+.BR shmget (2),
+.BR shmop (2),
+.BR shm_open (3),
+.BR shm_unlink (3),
+.BR sem_overview (7)
diff --git a/man/man7/sigevent.7 b/man/man7/sigevent.7
new file mode 100644
index 000000000..b43f1bbe8
--- /dev/null
+++ b/man/man7/sigevent.7
@@ -0,0 +1 @@
+.so man3type/sigevent.3type
diff --git a/man/man7/signal-safety.7 b/man/man7/signal-safety.7
new file mode 100644
index 000000000..cde19a575
--- /dev/null
+++ b/man/man7/signal-safety.7
@@ -0,0 +1,341 @@
+'\" t
+.\" Copyright (c) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH signal-safety 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+signal-safety \- async-signal-safe functions
+.SH DESCRIPTION
+An
+.I async-signal-safe
+function is one that can be safely called from within a signal handler.
+Many functions are
+.I not
+async-signal-safe.
+In particular,
+nonreentrant functions are generally unsafe to call from a signal handler.
+.P
+The kinds of issues that render a function
+unsafe can be quickly understood when one considers
+the implementation of the
+.I stdio
+library, all of whose functions are not async-signal-safe.
+.P
+When performing buffered I/O on a file, the
+.I stdio
+functions must maintain a statically allocated data buffer
+along with associated counters and indexes (or pointers)
+that record the amount of data and the current position in the buffer.
+Suppose that the main program is in the middle of a call to a
+.I stdio
+function such as
+.BR printf (3)
+where the buffer and associated variables have been partially updated.
+If, at that moment,
+the program is interrupted by a signal handler that also calls
+.BR printf (3),
+then the second call to
+.BR printf (3)
+will operate on inconsistent data, with unpredictable results.
+.P
+To avoid problems with unsafe functions, there are two possible choices:
+.IP (a) 5
+Ensure that
+(1) the signal handler calls only async-signal-safe functions,
+and
+(2) the signal handler itself is reentrant
+with respect to global variables in the main program.
+.IP (b)
+Block signal delivery in the main program when calling functions
+that are unsafe or operating on global data that is also accessed
+by the signal handler.
+.P
+Generally, the second choice is difficult in programs of any complexity,
+so the first choice is taken.
+.P
+POSIX.1 specifies a set of functions that an implementation
+must make async-signal-safe.
+(An implementation may provide safe implementations of additional functions,
+but this is not required by the standard and other implementations
+may not provide the same guarantees.)
+.P
+In general, a function is async-signal-safe either because it is reentrant
+or because it is atomic with respect to signals
+(i.e., its execution can't be interrupted by a signal handler).
+.P
+The set of functions required to be async-signal-safe by POSIX.1
+is shown in the following table.
+The functions not otherwise noted were required to be async-signal-safe
+in POSIX.1-2001;
+the table details changes in the subsequent standards.
+.P
+.TS
+lb lb
+l l.
+Function	Notes
+\fBabort\fP(3)	Added in POSIX.1-2001 TC1
+\fBaccept\fP(2)
+\fBaccess\fP(2)
+\fBaio_error\fP(3)
+\fBaio_return\fP(3)
+\fBaio_suspend\fP(3)	See notes below
+\fBalarm\fP(2)
+\fBbind\fP(2)
+\fBcfgetispeed\fP(3)
+\fBcfgetospeed\fP(3)
+\fBcfsetispeed\fP(3)
+\fBcfsetospeed\fP(3)
+\fBchdir\fP(2)
+\fBchmod\fP(2)
+\fBchown\fP(2)
+\fBclock_gettime\fP(2)
+\fBclose\fP(2)
+\fBconnect\fP(2)
+\fBcreat\fP(2)
+\fBdup\fP(2)
+\fBdup2\fP(2)
+\fBexecl\fP(3)	T{
+Added in POSIX.1-2008; see notes below
+T}
+\fBexecle\fP(3)	See notes below
+\fBexecv\fP(3)	Added in POSIX.1-2008
+\fBexecve\fP(2)
+\fB_exit\fP(2)
+\fB_Exit\fP(2)
+\fBfaccessat\fP(2)	Added in POSIX.1-2008
+\fBfchdir\fP(2)	Added in POSIX.1-2008 TC1
+\fBfchmod\fP(2)
+\fBfchmodat\fP(2)	Added in POSIX.1-2008
+\fBfchown\fP(2)
+\fBfchownat\fP(2)	Added in POSIX.1-2008
+\fBfcntl\fP(2)
+\fBfdatasync\fP(2)
+\fBfexecve\fP(3)	Added in POSIX.1-2008
+\fBffs\fP(3)	Added in POSIX.1-2008 TC2
+\fBfork\fP(2)	See notes below
+\fBfstat\fP(2)
+\fBfstatat\fP(2)	Added in POSIX.1-2008
+\fBfsync\fP(2)
+\fBftruncate\fP(2)
+\fBfutimens\fP(3)	Added in POSIX.1-2008
+\fBgetegid\fP(2)
+\fBgeteuid\fP(2)
+\fBgetgid\fP(2)
+\fBgetgroups\fP(2)
+\fBgetpeername\fP(2)
+\fBgetpgrp\fP(2)
+\fBgetpid\fP(2)
+\fBgetppid\fP(2)
+\fBgetsockname\fP(2)
+\fBgetsockopt\fP(2)
+\fBgetuid\fP(2)
+\fBhtonl\fP(3)	Added in POSIX.1-2008 TC2
+\fBhtons\fP(3)	Added in POSIX.1-2008 TC2
+\fBkill\fP(2)
+\fBlink\fP(2)
+\fBlinkat\fP(2)	Added in POSIX.1-2008
+\fBlisten\fP(2)
+\fBlongjmp\fP(3)	T{
+Added in POSIX.1-2008 TC2; see notes below
+T}
+\fBlseek\fP(2)
+\fBlstat\fP(2)
+\fBmemccpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBmemchr\fP(3)	Added in POSIX.1-2008 TC2
+\fBmemcmp\fP(3)	Added in POSIX.1-2008 TC2
+\fBmemcpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBmemmove\fP(3)	Added in POSIX.1-2008 TC2
+\fBmemset\fP(3)	Added in POSIX.1-2008 TC2
+\fBmkdir\fP(2)
+\fBmkdirat\fP(2)	Added in POSIX.1-2008
+\fBmkfifo\fP(3)
+\fBmkfifoat\fP(3)	Added in POSIX.1-2008
+\fBmknod\fP(2)	Added in POSIX.1-2008
+\fBmknodat\fP(2)	Added in POSIX.1-2008
+\fBntohl\fP(3)	Added in POSIX.1-2008 TC2
+\fBntohs\fP(3)	Added in POSIX.1-2008 TC2
+\fBopen\fP(2)
+\fBopenat\fP(2)	Added in POSIX.1-2008
+\fBpause\fP(2)
+\fBpipe\fP(2)
+\fBpoll\fP(2)
+\fBposix_trace_event\fP(3)
+\fBpselect\fP(2)
+\fBpthread_kill\fP(3)	Added in POSIX.1-2008 TC1
+\fBpthread_self\fP(3)	Added in POSIX.1-2008 TC1
+\fBpthread_sigmask\fP(3)	Added in POSIX.1-2008 TC1
+\fBraise\fP(3)
+\fBread\fP(2)
+\fBreadlink\fP(2)
+\fBreadlinkat\fP(2)	Added in POSIX.1-2008
+\fBrecv\fP(2)
+\fBrecvfrom\fP(2)
+\fBrecvmsg\fP(2)
+\fBrename\fP(2)
+\fBrenameat\fP(2)	Added in POSIX.1-2008
+\fBrmdir\fP(2)
+\fBselect\fP(2)
+\fBsem_post\fP(3)
+\fBsend\fP(2)
+\fBsendmsg\fP(2)
+\fBsendto\fP(2)
+\fBsetgid\fP(2)
+\fBsetpgid\fP(2)
+\fBsetsid\fP(2)
+\fBsetsockopt\fP(2)
+\fBsetuid\fP(2)
+\fBshutdown\fP(2)
+\fBsigaction\fP(2)
+\fBsigaddset\fP(3)
+\fBsigdelset\fP(3)
+\fBsigemptyset\fP(3)
+\fBsigfillset\fP(3)
+\fBsigismember\fP(3)
+\fBsiglongjmp\fP(3)	T{
+Added in POSIX.1-2008 TC2; see notes below
+T}
+\fBsignal\fP(2)
+\fBsigpause\fP(3)
+\fBsigpending\fP(2)
+\fBsigprocmask\fP(2)
+\fBsigqueue\fP(2)
+\fBsigset\fP(3)
+\fBsigsuspend\fP(2)
+\fBsleep\fP(3)
+\fBsockatmark\fP(3)	Added in POSIX.1-2001 TC2
+\fBsocket\fP(2)
+\fBsocketpair\fP(2)
+\fBstat\fP(2)
+\fBstpcpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBstpncpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrcat\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrchr\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrcmp\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrcpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrcspn\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrlen\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrncat\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrncmp\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrncpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrnlen\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrpbrk\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrrchr\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrspn\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrstr\fP(3)	Added in POSIX.1-2008 TC2
+\fBstrtok_r\fP(3)	Added in POSIX.1-2008 TC2
+\fBsymlink\fP(2)
+\fBsymlinkat\fP(2)	Added in POSIX.1-2008
+\fBtcdrain\fP(3)
+\fBtcflow\fP(3)
+\fBtcflush\fP(3)
+\fBtcgetattr\fP(3)
+\fBtcgetpgrp\fP(3)
+\fBtcsendbreak\fP(3)
+\fBtcsetattr\fP(3)
+\fBtcsetpgrp\fP(3)
+\fBtime\fP(2)
+\fBtimer_getoverrun\fP(2)
+\fBtimer_gettime\fP(2)
+\fBtimer_settime\fP(2)
+\fBtimes\fP(2)
+\fBumask\fP(2)
+\fBuname\fP(2)
+\fBunlink\fP(2)
+\fBunlinkat\fP(2)	Added in POSIX.1-2008
+\fButime\fP(2)
+\fButimensat\fP(2)	Added in POSIX.1-2008
+\fButimes\fP(2)	Added in POSIX.1-2008
+\fBwait\fP(2)
+\fBwaitpid\fP(2)
+\fBwcpcpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcpncpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcscat\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcschr\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcscmp\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcscpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcscspn\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcslen\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcsncat\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcsncmp\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcsncpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcsnlen\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcspbrk\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcsrchr\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcsspn\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcsstr\fP(3)	Added in POSIX.1-2008 TC2
+\fBwcstok\fP(3)	Added in POSIX.1-2008 TC2
+\fBwmemchr\fP(3)	Added in POSIX.1-2008 TC2
+\fBwmemcmp\fP(3)	Added in POSIX.1-2008 TC2
+\fBwmemcpy\fP(3)	Added in POSIX.1-2008 TC2
+\fBwmemmove\fP(3)	Added in POSIX.1-2008 TC2
+\fBwmemset\fP(3)	Added in POSIX.1-2008 TC2
+\fBwrite\fP(2)
+.TE
+.P
+Notes:
+.IP \[bu] 3
+POSIX.1-2001 and POSIX.1-2001 TC2 required the functions
+.BR fpathconf (3),
+.BR pathconf (3),
+and
+.BR sysconf (3)
+to be async-signal-safe, but this requirement was removed in POSIX.1-2008.
+.IP \[bu]
+If a signal handler interrupts the execution of an unsafe function,
+and the handler terminates via a call to
+.BR longjmp (3)
+or
+.BR siglongjmp (3)
+and the program subsequently calls an unsafe function,
+then the behavior of the program is undefined.
+.IP \[bu]
+POSIX.1-2001 TC1 clarified
+that if an application calls
+.BR fork (2)
+from a signal handler and any of the fork handlers registered by
+.BR pthread_atfork (3)
+calls a function that is not async-signal-safe, the behavior is undefined.
+A future revision of the standard
+.\" http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt
+is likely to remove
+.BR fork (2)
+from the list of async-signal-safe functions.
+.\"
+.IP \[bu]
+Asynchronous signal handlers that call functions which are cancelation
+points and nest over regions of deferred cancelation may trigger
+cancelation whose behavior is as if asynchronous cancelation had
+occurred and may cause application state to become inconsistent.
+.\"
+.SS errno
+Fetching and setting the value of
+.I errno
+is async-signal-safe provided that the signal handler saves
+.I errno
+on entry and restores its value before returning.
+.\"
+.SS Deviations in the GNU C library
+The following known deviations from the standard occur in
+the GNU C library:
+.IP \[bu] 3
+Before glibc 2.24,
+.BR execl (3)
+and
+.BR execle (3)
+employed
+.BR realloc (3)
+internally and were consequently not async-signal-safe.
+.\" https://sourceware.org/bugzilla/show_bug.cgi?id=19534
+This was fixed in glibc 2.24.
+.IP \[bu]
+.\" FIXME . https://sourceware.org/bugzilla/show_bug.cgi?id=13172
+The glibc implementation of
+.BR aio_suspend (3)
+is not async-signal-safe because it uses
+.BR pthread_mutex_lock (3)
+internally.
+.SH SEE ALSO
+.BR sigaction (2),
+.BR signal (7),
+.BR standards (7)
diff --git a/man/man7/signal.7 b/man/man7/signal.7
new file mode 100644
index 000000000..4ba5306c8
--- /dev/null
+++ b/man/man7/signal.7
@@ -0,0 +1,1019 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" and Copyright (c) 2002, 2006, 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 17:34:08 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Modified Sun Jan  7 01:41:27 1996 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Sun Apr 14 12:02:29 1996 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified Sat Nov 13 16:28:23 1999 by Andries Brouwer (aeb@cwi.nl)
+.\" Modified 10 Apr 2002, by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Modified  7 Jun 2002, by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Added information on real-time signals
+.\" Modified 13 Jun 2002, by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"	Noted that SIGSTKFLT is in fact unused
+.\" 2004-12-03, Modified mtk, added notes on RLIMIT_SIGPENDING
+.\" 2006-04-24, mtk, Added text on changing signal dispositions,
+.\"		signal mask, and pending signals.
+.\" 2008-07-04, mtk:
+.\"     Added section on system call restarting (SA_RESTART)
+.\"     Added section on stop/cont signals interrupting syscalls.
+.\" 2008-10-05, mtk: various additions
+.\"
+.TH signal 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+signal \- overview of signals
+.SH DESCRIPTION
+Linux supports both POSIX reliable signals (hereinafter
+"standard signals") and POSIX real-time signals.
+.SS Signal dispositions
+Each signal has a current
+.IR disposition ,
+which determines how the process behaves when it is delivered
+the signal.
+.P
+The entries in the "Action" column of the table below specify
+the default disposition for each signal, as follows:
+.TP
+Term
+Default action is to terminate the process.
+.TP
+Ign
+Default action is to ignore the signal.
+.TP
+Core
+Default action is to terminate the process and dump core (see
+.BR core (5)).
+.TP
+Stop
+Default action is to stop the process.
+.TP
+Cont
+Default action is to continue the process if it is currently stopped.
+.P
+A process can change the disposition of a signal using
+.BR sigaction (2)
+or
+.BR signal (2).
+(The latter is less portable when establishing a signal handler;
+see
+.BR signal (2)
+for details.)
+Using these system calls, a process can elect one of the
+following behaviors to occur on delivery of the signal:
+perform the default action; ignore the signal;
+or catch the signal with a
+.IR "signal handler" ,
+a programmer-defined function that is automatically invoked
+when the signal is delivered.
+.P
+By default, a signal handler is invoked on the
+normal process stack.
+It is possible to arrange that the signal handler
+uses an alternate stack; see
+.BR sigaltstack (2)
+for a discussion of how to do this and when it might be useful.
+.P
+The signal disposition is a per-process attribute:
+in a multithreaded application, the disposition of a
+particular signal is the same for all threads.
+.P
+A child created via
+.BR fork (2)
+inherits a copy of its parent's signal dispositions.
+During an
+.BR execve (2),
+the dispositions of handled signals are reset to the default;
+the dispositions of ignored signals are left unchanged.
+.SS Sending a signal
+The following system calls and library functions allow
+the caller to send a signal:
+.TP
+.BR raise (3)
+Sends a signal to the calling thread.
+.TP
+.BR kill (2)
+Sends a signal to a specified process,
+to all members of a specified process group,
+or to all processes on the system.
+.TP
+.BR pidfd_send_signal (2)
+Sends a signal to a process identified by a PID file descriptor.
+.TP
+.BR killpg (3)
+Sends a signal to all of the members of a specified process group.
+.TP
+.BR pthread_kill (3)
+Sends a signal to a specified POSIX thread in the same process as
+the caller.
+.TP
+.BR tgkill (2)
+Sends a signal to a specified thread within a specific process.
+(This is the system call used to implement
+.BR pthread_kill (3).)
+.TP
+.BR sigqueue (3)
+Sends a real-time signal with accompanying data to a specified process.
+.SS Waiting for a signal to be caught
+The following system calls suspend execution of the calling
+thread until a signal is caught
+(or an unhandled signal terminates the process):
+.TP
+.BR pause (2)
+Suspends execution until any signal is caught.
+.TP
+.BR sigsuspend (2)
+Temporarily changes the signal mask (see below) and suspends
+execution until one of the unmasked signals is caught.
+.\"
+.SS Synchronously accepting a signal
+Rather than asynchronously catching a signal via a signal handler,
+it is possible to synchronously accept the signal, that is,
+to block execution until the signal is delivered,
+at which point the kernel returns information about the
+signal to the caller.
+There are two general ways to do this:
+.IP \[bu] 3
+.BR sigwaitinfo (2),
+.BR sigtimedwait (2),
+and
+.BR sigwait (3)
+suspend execution until one of the signals in a specified
+set is delivered.
+Each of these calls returns information about the delivered signal.
+.IP \[bu]
+.BR signalfd (2)
+returns a file descriptor that can be used to read information
+about signals that are delivered to the caller.
+Each
+.BR read (2)
+from this file descriptor blocks until one of the signals
+in the set specified in the
+.BR signalfd (2)
+call is delivered to the caller.
+The buffer returned by
+.BR read (2)
+contains a structure describing the signal.
+.SS Signal mask and pending signals
+A signal may be
+.IR blocked ,
+which means that it will not be delivered until it is later unblocked.
+Between the time when it is generated and when it is delivered
+a signal is said to be
+.IR pending .
+.P
+Each thread in a process has an independent
+.IR "signal mask" ,
+which indicates the set of signals that the thread is currently blocking.
+A thread can manipulate its signal mask using
+.BR pthread_sigmask (3).
+In a traditional single-threaded application,
+.BR sigprocmask (2)
+can be used to manipulate the signal mask.
+.P
+A child created via
+.BR fork (2)
+inherits a copy of its parent's signal mask;
+the signal mask is preserved across
+.BR execve (2).
+.P
+A signal may be process-directed or thread-directed.
+A process-directed signal is one that is targeted at (and thus pending for)
+the process as a whole.
+A signal may be process-directed
+because it was generated by the kernel for reasons
+other than a hardware exception, or because it was sent using
+.BR kill (2)
+or
+.BR sigqueue (3).
+A thread-directed signal is one that is targeted at a specific thread.
+A signal may be thread-directed because it was generated as a consequence
+of executing a specific machine-language instruction
+that triggered a hardware exception (e.g.,
+.B SIGSEGV
+for an invalid memory access, or
+.B SIGFPE
+for a math error), or because it was
+targeted at a specific thread using
+interfaces such as
+.BR tgkill (2)
+or
+.BR pthread_kill (3).
+.P
+A process-directed signal may be delivered to any one of the
+threads that does not currently have the signal blocked.
+.\" Joseph C. Sible notes:
+.\" On Linux, if the main thread has the signal unblocked, then the kernel
+.\" will always deliver the signal there, citing this kernel code
+.\"
+.\"     Per this comment in kernel/signal.c since time immemorial:
+.\"
+.\"     /*
+.\"     * Now find a thread we can wake up to take the signal off the queue.
+.\"     *
+.\"     * If the main thread wants the signal, it gets first crack.
+.\"     * Probably the least surprising to the average bear.
+.\"     */
+.\"
+.\" But this does not mean the signal will be delivered only in the
+.\" main thread, since if a handler is already executing in the main thread
+.\" (and thus the signal is blocked in that thread), then a further
+.\" might be delivered in a different thread.
+.\"
+If more than one of the threads has the signal unblocked, then the
+kernel chooses an arbitrary thread to which to deliver the signal.
+.P
+A thread can obtain the set of signals that it currently has pending
+using
+.BR sigpending (2).
+This set will consist of the union of the set of pending
+process-directed signals and the set of signals pending for
+the calling thread.
+.P
+A child created via
+.BR fork (2)
+initially has an empty pending signal set;
+the pending signal set is preserved across an
+.BR execve (2).
+.\"
+.SS Execution of signal handlers
+Whenever there is a transition from kernel-mode to user-mode execution
+(e.g., on return from a system call or scheduling of a thread onto the CPU),
+the kernel checks whether there is a pending unblocked signal
+for which the process has established a signal handler.
+If there is such a pending signal, the following steps occur:
+.IP (1) 5
+The kernel performs the necessary preparatory steps for execution of
+the signal handler:
+.RS
+.IP (1.1) 7
+The signal is removed from the set of pending signals.
+.IP (1.2)
+If the signal handler was installed by a call to
+.BR sigaction (2)
+that specified the
+.B SA_ONSTACK
+flag and the thread has defined an alternate signal stack (using
+.BR sigaltstack (2)),
+then that stack is installed.
+.IP (1.3)
+Various pieces of signal-related context are saved
+into a special frame that is created on the stack.
+The saved information includes:
+.RS
+.IP \[bu] 3
+the program counter register
+(i.e., the address of the next instruction in the main program that
+should be executed when the signal handler returns);
+.IP \[bu]
+architecture-specific register state required for resuming the
+interrupted program;
+.IP \[bu]
+the thread's current signal mask;
+.IP \[bu]
+the thread's alternate signal stack settings.
+.RE
+.IP
+(If the signal handler was installed using the
+.BR sigaction (2)
+.B SA_SIGINFO
+flag, then the above information is accessible via the
+.I ucontext_t
+object that is pointed to by the third argument of the signal handler.)
+.IP (1.4)
+Any signals specified in
+.I act\->sa_mask
+when registering the handler with
+.BR sigprocmask (2)
+are added to the thread's signal mask.
+The signal being delivered is also
+added to the signal mask, unless
+.B SA_NODEFER
+was specified when registering the handler.
+These signals are thus blocked while the handler executes.
+.RE
+.IP (2)
+The kernel constructs a frame for the signal handler on the stack.
+The kernel sets the program counter for the thread to point to the first
+instruction of the signal handler function,
+and configures the return address for that function to point to a piece
+of user-space code known as the signal trampoline (described in
+.BR sigreturn (2)).
+.IP (3)
+The kernel passes control back to user-space, where execution
+commences at the start of the signal handler function.
+.IP (4)
+When the signal handler returns, control passes to the signal trampoline code.
+.IP (5)
+The signal trampoline calls
+.BR sigreturn (2),
+a system call that uses the information in the stack frame created in step 1
+to restore the thread to its state before the signal handler was
+called.
+The thread's signal mask and alternate signal stack settings
+are restored as part of this procedure.
+Upon completion of the call to
+.BR sigreturn (2),
+the kernel transfers control back to user space,
+and the thread recommences execution at the point where it was
+interrupted by the signal handler.
+.P
+Note that if the signal handler does not return
+(e.g., control is transferred out of the handler using
+.BR siglongjmp (3),
+or the handler executes a new program with
+.BR execve (2)),
+then the final step is not performed.
+In particular, in such scenarios it is the programmer's responsibility
+to restore the state of the signal mask (using
+.BR sigprocmask (2)),
+if it is desired to unblock the signals that were blocked on entry
+to the signal handler.
+(Note that
+.BR siglongjmp (3)
+may or may not restore the signal mask, depending on the
+.I savesigs
+value that was specified in the corresponding call to
+.BR sigsetjmp (3).)
+.P
+From the kernel's point of view,
+execution of the signal handler code is exactly the same as the execution
+of any other user-space code.
+That is to say, the kernel does not record any special state information
+indicating that the thread is currently executing inside a signal handler.
+All necessary state information is maintained in user-space registers
+and the user-space stack.
+The depth to which nested signal handlers may be invoked is thus
+limited only by the user-space stack (and sensible software design!).
+.\"
+.SS Standard signals
+Linux supports the standard signals listed below.
+The second column of the table indicates which standard (if any)
+specified the signal: "P1990" indicates that the signal is described
+in the original POSIX.1-1990 standard;
+"P2001" indicates that the signal was added in SUSv2 and POSIX.1-2001.
+.TS
+l c c l
+____
+lB c c l.
+Signal	Standard	Action	Comment
+SIGABRT	P1990	Core	Abort signal from \fBabort\fP(3)
+SIGALRM	P1990	Term	Timer signal from \fBalarm\fP(2)
+SIGBUS	P2001	Core	Bus error (bad memory access)
+SIGCHLD	P1990	Ign	Child stopped or terminated
+SIGCLD	\-	Ign	A synonym for \fBSIGCHLD\fP
+SIGCONT	P1990	Cont	Continue if stopped
+SIGEMT	\-	Term	Emulator trap
+SIGFPE	P1990	Core	Floating-point exception
+SIGHUP	P1990	Term	Hangup detected on controlling terminal
+			or death of controlling process
+SIGILL	P1990	Core	Illegal Instruction
+SIGINFO	\-		A synonym for \fBSIGPWR\fP
+SIGINT	P1990	Term	Interrupt from keyboard
+SIGIO	\-	Term	I/O now possible (4.2BSD)
+SIGIOT	\-	Core	IOT trap. A synonym for \fBSIGABRT\fP
+SIGKILL	P1990	Term	Kill signal
+SIGLOST	\-	Term	File lock lost (unused)
+SIGPIPE	P1990	Term	Broken pipe: write to pipe with no
+			readers; see \fBpipe\fP(7)
+SIGPOLL	P2001	Term	Pollable event (Sys V);
+			synonym for \fBSIGIO\fP
+SIGPROF	P2001	Term	Profiling timer expired
+SIGPWR	\-	Term	Power failure (System V)
+SIGQUIT	P1990	Core	Quit from keyboard
+SIGSEGV	P1990	Core	Invalid memory reference
+SIGSTKFLT	\-	Term	Stack fault on coprocessor (unused)
+SIGSTOP	P1990	Stop	Stop process
+SIGTSTP	P1990	Stop	Stop typed at terminal
+SIGSYS	P2001	Core	Bad system call (SVr4);
+			see also \fBseccomp\fP(2)
+SIGTERM	P1990	Term	Termination signal
+SIGTRAP	P2001	Core	Trace/breakpoint trap
+SIGTTIN	P1990	Stop	Terminal input for background process
+SIGTTOU	P1990	Stop	Terminal output for background process
+SIGUNUSED	\-	Core	Synonymous with \fBSIGSYS\fP
+SIGURG	P2001	Ign	Urgent condition on socket (4.2BSD)
+SIGUSR1	P1990	Term	User-defined signal 1
+SIGUSR2	P1990	Term	User-defined signal 2
+SIGVTALRM	P2001	Term	Virtual alarm clock (4.2BSD)
+SIGXCPU	P2001	Core	CPU time limit exceeded (4.2BSD);
+			see \fBsetrlimit\fP(2)
+SIGXFSZ	P2001	Core	File size limit exceeded (4.2BSD);
+			see \fBsetrlimit\fP(2)
+SIGWINCH	\-	Ign	Window resize signal (4.3BSD, Sun)
+.TE
+.P
+The signals
+.B SIGKILL
+and
+.B SIGSTOP
+cannot be caught, blocked, or ignored.
+.P
+Up to and including Linux 2.2, the default behavior for
+.BR SIGSYS ", " SIGXCPU ", " SIGXFSZ ,
+and (on architectures other than SPARC and MIPS)
+.B SIGBUS
+was to terminate the process (without a core dump).
+(On some other UNIX systems the default action for
+.BR SIGXCPU " and " SIGXFSZ
+is to terminate the process without a core dump.)
+Linux 2.4 conforms to the POSIX.1-2001 requirements for these signals,
+terminating the process with a core dump.
+.P
+.B SIGEMT
+is not specified in POSIX.1-2001, but nevertheless appears
+on most other UNIX systems,
+where its default action is typically to terminate
+the process with a core dump.
+.P
+.B SIGPWR
+(which is not specified in POSIX.1-2001) is typically ignored
+by default on those other UNIX systems where it appears.
+.P
+.B SIGIO
+(which is not specified in POSIX.1-2001) is ignored by default
+on several other UNIX systems.
+.\"
+.SS Queueing and delivery semantics for standard signals
+If multiple standard signals are pending for a process,
+the order in which the signals are delivered is unspecified.
+.P
+Standard signals do not queue.
+If multiple instances of a standard signal are generated while
+that signal is blocked,
+then only one instance of the signal is marked as pending
+(and the signal will be delivered just once when it is unblocked).
+In the case where a standard signal is already pending, the
+.I siginfo_t
+structure (see
+.BR sigaction (2))
+associated with that signal is not overwritten
+on arrival of subsequent instances of the same signal.
+Thus, the process will receive the information
+associated with the first instance of the signal.
+.\"
+.SS Signal numbering for standard signals
+The numeric value for each signal is given in the table below.
+As shown in the table, many signals have different numeric values
+on different architectures.
+The first numeric value in each table row shows the signal number
+on x86, ARM, and most other architectures;
+the second value is for Alpha and SPARC; the third is for MIPS;
+and the last is for PARISC.
+A dash (\-) denotes that a signal is absent on the corresponding architecture.
+.TS
+l c c c c l
+l c c c c l
+______
+lB c c c c l.
+Signal	x86/ARM	Alpha/	MIPS	PARISC	Notes
+	most others	SPARC
+SIGHUP	\01	\01	\01	\01
+SIGINT	\02	\02	\02	\02
+SIGQUIT	\03	\03	\03	\03
+SIGILL	\04	\04	\04	\04
+SIGTRAP	\05	\05	\05	\05
+SIGABRT	\06	\06	\06	\06
+SIGIOT	\06	\06	\06	\06
+SIGBUS	\07	10	10	10
+SIGEMT	\-	\07	\07	-
+SIGFPE	\08	\08	\08	\08
+SIGKILL	\09	\09	\09	\09
+SIGUSR1	10	30	16	16
+SIGSEGV	11	11	11	11
+SIGUSR2	12	31	17	17
+SIGPIPE	13	13	13	13
+SIGALRM	14	14	14	14
+SIGTERM	15	15	15	15
+SIGSTKFLT	16	\-	\-	\07
+SIGCHLD	17	20	18	18
+SIGCLD	\-	\-	18	\-
+SIGCONT	18	19	25	26
+SIGSTOP	19	17	23	24
+SIGTSTP	20	18	24	25
+SIGTTIN	21	21	26	27
+SIGTTOU	22	22	27	28
+SIGURG	23	16	21	29
+SIGXCPU	24	24	30	12
+SIGXFSZ	25	25	31	30
+SIGVTALRM	26	26	28	20
+SIGPROF	27	27	29	21
+SIGWINCH	28	28	20	23
+SIGIO	29	23	22	22
+SIGPOLL					Same as SIGIO
+SIGPWR	30	29/\-	19	19
+SIGINFO	\-	29/\-	\-	\-
+SIGLOST	\-	\-/29	\-	\-
+SIGSYS	31	12	12	31
+SIGUNUSED	31	\-	\-	31
+.TE
+.P
+Note the following:
+.IP \[bu] 3
+Where defined,
+.B SIGUNUSED
+is synonymous with
+.BR SIGSYS .
+Since glibc 2.26,
+.B SIGUNUSED
+is no longer defined on any architecture.
+.IP \[bu]
+Signal 29 is
+.BR SIGINFO / SIGPWR
+(synonyms for the same value) on Alpha but
+.B SIGLOST
+on SPARC.
+.\"
+.SS Real-time signals
+Starting with Linux 2.2,
+Linux supports real-time signals as originally defined in the POSIX.1b
+real-time extensions (and now included in POSIX.1-2001).
+The range of supported real-time signals is defined by the macros
+.B SIGRTMIN
+and
+.BR SIGRTMAX .
+POSIX.1-2001 requires that an implementation support at least
+.B _POSIX_RTSIG_MAX
+(8) real-time signals.
+.P
+The Linux kernel supports a range of 33 different real-time
+signals, numbered 32 to 64.
+However, the glibc POSIX threads implementation internally uses
+two (for NPTL) or three (for LinuxThreads) real-time signals
+(see
+.BR pthreads (7)),
+and adjusts the value of
+.B SIGRTMIN
+suitably (to 34 or 35).
+Because the range of available real-time signals varies according
+to the glibc threading implementation (and this variation can occur
+at run time according to the available kernel and glibc),
+and indeed the range of real-time signals varies across UNIX systems,
+programs should
+.IR "never refer to real-time signals using hard-coded numbers" ,
+but instead should always refer to real-time signals using the notation
+.BR SIGRTMIN +n,
+and include suitable (run-time) checks that
+.BR SIGRTMIN +n
+does not exceed
+.BR SIGRTMAX .
+.P
+Unlike standard signals, real-time signals have no predefined meanings:
+the entire set of real-time signals can be used for application-defined
+purposes.
+.P
+The default action for an unhandled real-time signal is to terminate the
+receiving process.
+.P
+Real-time signals are distinguished by the following:
+.IP \[bu] 3
+Multiple instances of real-time signals can be queued.
+By contrast, if multiple instances of a standard signal are delivered
+while that signal is currently blocked, then only one instance is queued.
+.IP \[bu]
+If the signal is sent using
+.BR sigqueue (3),
+an accompanying value (either an integer or a pointer) can be sent
+with the signal.
+If the receiving process establishes a handler for this signal using the
+.B SA_SIGINFO
+flag to
+.BR sigaction (2),
+then it can obtain this data via the
+.I si_value
+field of the
+.I siginfo_t
+structure passed as the second argument to the handler.
+Furthermore, the
+.I si_pid
+and
+.I si_uid
+fields of this structure can be used to obtain the PID
+and real user ID of the process sending the signal.
+.IP \[bu]
+Real-time signals are delivered in a guaranteed order.
+Multiple real-time signals of the same type are delivered in the order
+they were sent.
+If different real-time signals are sent to a process, they are delivered
+starting with the lowest-numbered signal.
+(I.e., low-numbered signals have highest priority.)
+By contrast, if multiple standard signals are pending for a process,
+the order in which they are delivered is unspecified.
+.P
+If both standard and real-time signals are pending for a process,
+POSIX leaves it unspecified which is delivered first.
+Linux, like many other implementations, gives priority
+to standard signals in this case.
+.P
+According to POSIX, an implementation should permit at least
+.B _POSIX_SIGQUEUE_MAX
+(32) real-time signals to be queued to
+a process.
+However, Linux does things differently.
+Up to and including Linux 2.6.7, Linux imposes
+a system-wide limit on the number of queued real-time signals
+for all processes.
+This limit can be viewed and (with privilege) changed via the
+.I /proc/sys/kernel/rtsig\-max
+file.
+A related file,
+.IR /proc/sys/kernel/rtsig\-nr ,
+can be used to find out how many real-time signals are currently queued.
+In Linux 2.6.8, these
+.I /proc
+interfaces were replaced by the
+.B RLIMIT_SIGPENDING
+resource limit, which specifies a per-user limit for queued
+signals; see
+.BR setrlimit (2)
+for further details.
+.P
+The addition of real-time signals required the widening
+of the signal set structure
+.RI ( sigset_t )
+from 32 to 64 bits.
+Consequently, various system calls were superseded by new system calls
+that supported the larger signal sets.
+The old and new system calls are as follows:
+.TS
+lb lb
+l l.
+Linux 2.0 and earlier	Linux 2.2 and later
+\fBsigaction\fP(2)	\fBrt_sigaction\fP(2)
+\fBsigpending\fP(2)	\fBrt_sigpending\fP(2)
+\fBsigprocmask\fP(2)	\fBrt_sigprocmask\fP(2)
+\fBsigreturn\fP(2)	\fBrt_sigreturn\fP(2)
+\fBsigsuspend\fP(2)	\fBrt_sigsuspend\fP(2)
+\fBsigtimedwait\fP(2)	\fBrt_sigtimedwait\fP(2)
+.TE
+.\"
+.SS Interruption of system calls and library functions by signal handlers
+If a signal handler is invoked while a system call or library
+function call is blocked, then either:
+.IP \[bu] 3
+the call is automatically restarted after the signal handler returns; or
+.IP \[bu]
+the call fails with the error
+.BR EINTR .
+.P
+Which of these two behaviors occurs depends on the interface and
+whether or not the signal handler was established using the
+.B SA_RESTART
+flag (see
+.BR sigaction (2)).
+The details vary across UNIX systems;
+below, the details for Linux.
+.P
+If a blocked call to one of the following interfaces is interrupted
+by a signal handler, then the call is automatically restarted
+after the signal handler returns if the
+.B SA_RESTART
+flag was used; otherwise the call fails with the error
+.BR EINTR :
+.\" The following system calls use ERESTARTSYS,
+.\" so that they are restartable
+.IP \[bu] 3
+.BR read (2),
+.BR readv (2),
+.BR write (2),
+.BR writev (2),
+and
+.BR ioctl (2)
+calls on "slow" devices.
+A "slow" device is one where the I/O call may block for an
+indefinite time, for example, a terminal, pipe, or socket.
+If an I/O call on a slow device has already transferred some
+data by the time it is interrupted by a signal handler,
+then the call will return a success status
+(normally, the number of bytes transferred).
+Note that a (local) disk is not a slow device according to this definition;
+I/O operations on disk devices are not interrupted by signals.
+.IP \[bu]
+.BR open (2),
+if it can block (e.g., when opening a FIFO; see
+.BR fifo (7)).
+.IP \[bu]
+.BR wait (2),
+.BR wait3 (2),
+.BR wait4 (2),
+.BR waitid (2),
+and
+.BR waitpid (2).
+.IP \[bu]
+Socket interfaces:
+.\" If a timeout (setsockopt()) is in effect on the socket, then these
+.\" system calls switch to using EINTR.  Consequently, they and are not
+.\" automatically restarted, and they show the stop/cont behavior
+.\" described below.  (Verified from Linux 2.6.26 source, and by experiment; mtk)
+.BR accept (2),
+.BR connect (2),
+.BR recv (2),
+.BR recvfrom (2),
+.BR recvmmsg (2),
+.BR recvmsg (2),
+.BR send (2),
+.BR sendto (2),
+and
+.BR sendmsg (2),
+.\" FIXME What about sendmmsg()?
+unless a timeout has been set on the socket (see below).
+.IP \[bu]
+File locking interfaces:
+.BR flock (2)
+and
+the
+.B F_SETLKW
+and
+.B F_OFD_SETLKW
+operations of
+.BR fcntl (2)
+.IP \[bu]
+POSIX message queue interfaces:
+.BR mq_receive (3),
+.BR mq_timedreceive (3),
+.BR mq_send (3),
+and
+.BR mq_timedsend (3).
+.IP \[bu]
+.BR futex (2)
+.B FUTEX_WAIT
+(since Linux 2.6.22;
+.\" commit 72c1bbf308c75a136803d2d76d0e18258be14c7a
+beforehand, always failed with
+.BR EINTR ).
+.IP \[bu]
+.BR getrandom (2).
+.IP \[bu]
+.BR pthread_mutex_lock (3),
+.BR pthread_cond_wait (3),
+and related APIs.
+.IP \[bu]
+.BR futex (2)
+.BR FUTEX_WAIT_BITSET .
+.IP \[bu]
+POSIX semaphore interfaces:
+.BR sem_wait (3)
+and
+.BR sem_timedwait (3)
+(since Linux 2.6.22;
+.\" as a consequence of the 2.6.22 changes in the futex() implementation
+beforehand, always failed with
+.BR EINTR ).
+.IP \[bu]
+.BR read (2)
+from an
+.BR inotify (7)
+file descriptor
+(since Linux 3.8;
+.\" commit 1ca39ab9d21ac93f94b9e3eb364ea9a5cf2aba06
+beforehand, always failed with
+.BR EINTR ).
+.P
+The following interfaces are never restarted after
+being interrupted by a signal handler,
+regardless of the use of
+.BR SA_RESTART ;
+they always fail with the error
+.B EINTR
+when interrupted by a signal handler:
+.\" These are the system calls that give EINTR or ERESTARTNOHAND
+.\" on interruption by a signal handler.
+.IP \[bu] 3
+"Input" socket interfaces, when a timeout
+.RB ( SO_RCVTIMEO )
+has been set on the socket using
+.BR setsockopt (2):
+.BR accept (2),
+.BR recv (2),
+.BR recvfrom (2),
+.BR recvmmsg (2)
+(also with a non-NULL
+.I timeout
+argument),
+and
+.BR recvmsg (2).
+.IP \[bu]
+"Output" socket interfaces, when a timeout
+.RB ( SO_RCVTIMEO )
+has been set on the socket using
+.BR setsockopt (2):
+.BR connect (2),
+.BR send (2),
+.BR sendto (2),
+and
+.BR sendmsg (2).
+.\" FIXME What about sendmmsg()?
+.IP \[bu]
+Interfaces used to wait for signals:
+.BR pause (2),
+.BR sigsuspend (2),
+.BR sigtimedwait (2),
+and
+.BR sigwaitinfo (2).
+.IP \[bu]
+File descriptor multiplexing interfaces:
+.BR epoll_wait (2),
+.BR epoll_pwait (2),
+.BR poll (2),
+.BR ppoll (2),
+.BR select (2),
+and
+.BR pselect (2).
+.IP \[bu]
+System V IPC interfaces:
+.\" On some other systems, SA_RESTART does restart these system calls
+.BR msgrcv (2),
+.BR msgsnd (2),
+.BR semop (2),
+and
+.BR semtimedop (2).
+.IP \[bu]
+Sleep interfaces:
+.BR clock_nanosleep (2),
+.BR nanosleep (2),
+and
+.BR usleep (3).
+.IP \[bu]
+.BR io_getevents (2).
+.P
+The
+.BR sleep (3)
+function is also never restarted if interrupted by a handler,
+but gives a success return: the number of seconds remaining to sleep.
+.P
+In certain circumstances, the
+.BR seccomp (2)
+user-space notification feature can lead to restarting of system calls
+that would otherwise never be restarted by
+.BR SA_RESTART ;
+for details, see
+.BR seccomp_unotify (2).
+.\"
+.SS Interruption of system calls and library functions by stop signals
+On Linux, even in the absence of signal handlers,
+certain blocking interfaces can fail with the error
+.B EINTR
+after the process is stopped by one of the stop signals
+and then resumed via
+.BR SIGCONT .
+This behavior is not sanctioned by POSIX.1, and doesn't occur
+on other systems.
+.P
+The Linux interfaces that display this behavior are:
+.IP \[bu] 3
+"Input" socket interfaces, when a timeout
+.RB ( SO_RCVTIMEO )
+has been set on the socket using
+.BR setsockopt (2):
+.BR accept (2),
+.BR recv (2),
+.BR recvfrom (2),
+.BR recvmmsg (2)
+(also with a non-NULL
+.I timeout
+argument),
+and
+.BR recvmsg (2).
+.IP \[bu]
+"Output" socket interfaces, when a timeout
+.RB ( SO_RCVTIMEO )
+has been set on the socket using
+.BR setsockopt (2):
+.BR connect (2),
+.BR send (2),
+.BR sendto (2),
+and
+.\" FIXME What about sendmmsg()?
+.BR sendmsg (2),
+if a send timeout
+.RB ( SO_SNDTIMEO )
+has been set.
+.IP \[bu]
+.BR epoll_wait (2),
+.BR epoll_pwait (2).
+.IP \[bu]
+.BR semop (2),
+.BR semtimedop (2).
+.IP \[bu]
+.BR sigtimedwait (2),
+.BR sigwaitinfo (2).
+.IP \[bu]
+Linux 3.7 and earlier:
+.BR read (2)
+from an
+.BR inotify (7)
+file descriptor
+.\" commit 1ca39ab9d21ac93f94b9e3eb364ea9a5cf2aba06
+.IP \[bu]
+Linux 2.6.21 and earlier:
+.BR futex (2)
+.BR FUTEX_WAIT ,
+.BR sem_timedwait (3),
+.BR sem_wait (3).
+.IP \[bu]
+Linux 2.6.8 and earlier:
+.BR msgrcv (2),
+.BR msgsnd (2).
+.IP \[bu]
+Linux 2.4 and earlier:
+.BR nanosleep (2).
+.SH STANDARDS
+POSIX.1, except as noted.
+.SH NOTES
+For a discussion of async-signal-safe functions, see
+.BR signal\-safety (7).
+.P
+The
+.IR /proc/ pid /task/ tid /status
+file contains various fields that show the signals
+that a thread is blocking
+.RI ( SigBlk ),
+catching
+.RI ( SigCgt ),
+or ignoring
+.RI ( SigIgn ).
+(The set of signals that are caught or ignored will be the same
+across all threads in a process.)
+Other fields show the set of pending signals that are directed to the thread
+.RI ( SigPnd )
+as well as the set of pending signals that are directed
+to the process as a whole
+.RI ( ShdPnd ).
+The corresponding fields in
+.IR /proc/ pid /status
+show the information for the main thread.
+See
+.BR proc (5)
+for further details.
+.SH BUGS
+There are six signals that can be delivered
+as a consequence of a hardware exception:
+.BR SIGBUS ,
+.BR SIGEMT ,
+.BR SIGFPE ,
+.BR SIGILL ,
+.BR SIGSEGV ,
+and
+.BR SIGTRAP .
+Which of these signals is delivered,
+for any given hardware exception,
+is not documented and does not always make sense.
+.P
+For example, an invalid memory access that causes delivery of
+.B SIGSEGV
+on one CPU architecture may cause delivery of
+.B SIGBUS
+on another architecture, or vice versa.
+.P
+For another example, using the x86
+.I int
+instruction with a forbidden argument
+(any number other than 3 or 128)
+causes delivery of
+.BR SIGSEGV ,
+even though
+.B SIGILL
+would make more sense,
+because of how the CPU reports the forbidden operation to the kernel.
+.SH SEE ALSO
+.BR kill (1),
+.BR clone (2),
+.BR getrlimit (2),
+.BR kill (2),
+.BR pidfd_send_signal (2),
+.BR restart_syscall (2),
+.BR rt_sigqueueinfo (2),
+.BR setitimer (2),
+.BR setrlimit (2),
+.BR sgetmask (2),
+.BR sigaction (2),
+.BR sigaltstack (2),
+.BR signal (2),
+.BR signalfd (2),
+.BR sigpending (2),
+.BR sigprocmask (2),
+.BR sigreturn (2),
+.BR sigsuspend (2),
+.BR sigwaitinfo (2),
+.BR abort (3),
+.BR bsd_signal (3),
+.BR killpg (3),
+.BR longjmp (3),
+.BR pthread_sigqueue (3),
+.BR raise (3),
+.BR sigqueue (3),
+.BR sigset (3),
+.BR sigsetops (3),
+.BR sigvec (3),
+.BR sigwait (3),
+.BR strsignal (3),
+.BR swapcontext (3),
+.BR sysv_signal (3),
+.BR core (5),
+.BR proc (5),
+.BR nptl (7),
+.BR pthreads (7),
+.BR sigevent (3type)
diff --git a/man/man7/sock_diag.7 b/man/man7/sock_diag.7
new file mode 100644
index 000000000..962c3edf3
--- /dev/null
+++ b/man/man7/sock_diag.7
@@ -0,0 +1,825 @@
+.\" Copyright (c) 2016 Pavel Emelyanov <xemul@virtuozzo.com>
+.\" Copyright (c) 2016 Dmitry V. Levin <ldv@altlinux.org>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.TH sock_diag 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sock_diag \- obtaining information about sockets
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <linux/sock_diag.h>
+.BR "#include <linux/unix_diag.h>" " /* for UNIX domain sockets */"
+.BR "#include <linux/inet_diag.h>" " /* for IPv4 and IPv6 sockets */"
+.P
+.BI "diag_socket = socket(AF_NETLINK, " socket_type ", NETLINK_SOCK_DIAG);"
+.fi
+.SH DESCRIPTION
+The sock_diag netlink subsystem provides a mechanism for obtaining
+information about sockets of various address families from the kernel.
+This subsystem can be used to obtain information about individual
+sockets or request a list of sockets.
+.P
+In the request, the caller can specify additional information it would
+like to obtain about the socket, for example, memory information or
+information specific to the address family.
+.P
+When requesting a list of sockets, the caller can specify filters that
+would be applied by the kernel to select a subset of sockets to report.
+For now, there is only the ability to filter sockets by state (connected,
+listening, and so on.)
+.P
+Note that sock_diag reports only those sockets that have a name;
+that is, either sockets bound explicitly with
+.BR bind (2)
+or sockets that were automatically bound to an address (e.g., by
+.BR connect (2)).
+This is the same set of sockets that is available via
+.IR /proc/net/unix ,
+.IR /proc/net/tcp ,
+.IR /proc/net/udp ,
+and so on.
+.\"
+.SS Request
+The request starts with a
+.I "struct nlmsghdr"
+header described in
+.BR netlink (7)
+with
+.I nlmsg_type
+field set to
+.BR SOCK_DIAG_BY_FAMILY .
+It is followed by a header specific to the address family that starts with
+a common part shared by all address families:
+.P
+.in +4n
+.EX
+struct sock_diag_req {
+    __u8 sdiag_family;
+    __u8 sdiag_protocol;
+};
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I sdiag_family
+An address family.
+It should be set to the appropriate
+.B AF_*
+constant.
+.TP
+.I sdiag_protocol
+Depends on
+.IR sdiag_family .
+It should be set to the appropriate
+.B IPPROTO_*
+constant for
+.B AF_INET
+and
+.BR AF_INET6 ,
+and to 0 otherwise.
+.P
+If the
+.I nlmsg_flags
+field of the
+.I "struct nlmsghdr"
+header has the
+.B NLM_F_DUMP
+flag set, it means that a list of sockets is being requested;
+otherwise it is a query about an individual socket.
+.\"
+.SS Response
+The response starts with a
+.I "struct nlmsghdr"
+header and is followed by an array of objects specific to the address family.
+The array is to be accessed with the standard
+.B NLMSG_*
+macros from the
+.BR netlink (3)
+API.
+.P
+Each object is the NLA (netlink attributes) list that is to be accessed
+with the
+.B RTA_*
+macros from
+.BR rtnetlink (3)
+API.
+.\"
+.SS UNIX domain sockets
+For UNIX domain sockets the request is represented in the following structure:
+.P
+.in +4n
+.EX
+struct unix_diag_req {
+    __u8    sdiag_family;
+    __u8    sdiag_protocol;
+    __u16   pad;
+    __u32   udiag_states;
+    __u32   udiag_ino;
+    __u32   udiag_show;
+    __u32   udiag_cookie[2];
+};
+.EE
+.in
+.P
+The fields of this structure are as follows:
+.TP
+.I sdiag_family
+The address family; it should be set to
+.BR AF_UNIX .
+.P
+.I sdiag_protocol
+.PD 0
+.TP
+.PD
+.I pad
+These fields should be set to 0.
+.TP
+.I udiag_states
+This is a bit mask that defines a filter of sockets states.
+Only those sockets whose states are in this mask will be reported.
+Ignored when querying for an individual socket.
+Supported values are:
+.P
+.RS 12
+1 <<
+.B TCP_ESTABLISHED
+.P
+1 <<
+.B TCP_LISTEN
+.RE
+.TP
+.I udiag_ino
+This is an inode number when querying for an individual socket.
+Ignored when querying for a list of sockets.
+.TP
+.I udiag_show
+This is a set of flags defining what kind of information to report.
+Each requested kind of information is reported back as a netlink
+attribute as described below:
+.RS
+.TP
+.B UDIAG_SHOW_NAME
+The attribute reported in answer to this request is
+.BR UNIX_DIAG_NAME .
+The payload associated with this attribute is the pathname to which
+the socket was bound (a sequence of bytes up to
+.B UNIX_PATH_MAX
+length).
+.TP
+.B UDIAG_SHOW_VFS
+The attribute reported in answer to this request is
+.BR UNIX_DIAG_VFS .
+The payload associated with this attribute is represented in the following
+structure:
+.IP
+.in +4n
+.EX
+struct unix_diag_vfs {
+    __u32 udiag_vfs_dev;
+    __u32 udiag_vfs_ino;
+};
+.EE
+.in
+.IP
+The fields of this structure are as follows:
+.RS
+.TP
+.I udiag_vfs_dev
+The device number of the corresponding on-disk socket inode.
+.TP
+.I udiag_vfs_ino
+The inode number of the corresponding on-disk socket inode.
+.RE
+.TP
+.B UDIAG_SHOW_PEER
+The attribute reported in answer to this request is
+.BR UNIX_DIAG_PEER .
+The payload associated with this attribute is a __u32 value
+which is the peer's inode number.
+This attribute is reported for connected sockets only.
+.TP
+.B UDIAG_SHOW_ICONS
+The attribute reported in answer to this request is
+.BR UNIX_DIAG_ICONS .
+The payload associated with this attribute is an array of __u32 values
+which are inode numbers of sockets that has passed the
+.BR connect (2)
+call, but hasn't been processed with
+.BR accept (2)
+yet.
+This attribute is reported for listening sockets only.
+.TP
+.B UDIAG_SHOW_RQLEN
+The attribute reported in answer to this request is
+.BR UNIX_DIAG_RQLEN .
+The payload associated with this attribute is represented in the following
+structure:
+.IP
+.in +4n
+.EX
+struct unix_diag_rqlen {
+    __u32 udiag_rqueue;
+    __u32 udiag_wqueue;
+};
+.EE
+.in
+.IP
+The fields of this structure are as follows:
+.RS
+.TP
+.I udiag_rqueue
+For listening sockets:
+the number of pending connections.
+The length of the array associated with the
+.B UNIX_DIAG_ICONS
+response attribute is equal to this value.
+.IP
+For established sockets:
+the amount of data in incoming queue.
+.TP
+.I udiag_wqueue
+For listening sockets:
+the backlog length which equals to the value passed as the second argument to
+.BR listen (2).
+.IP
+For established sockets:
+the amount of memory available for sending.
+.RE
+.TP
+.B UDIAG_SHOW_MEMINFO
+The attribute reported in answer to this request is
+.BR UNIX_DIAG_MEMINFO .
+The payload associated with this attribute is an array of __u32 values
+described below in the subsection "Socket memory information".
+.P
+The following attributes are reported back without any specific request:
+.TP
+.B UNIX_DIAG_SHUTDOWN
+The payload associated with this attribute is __u8 value which represents
+bits of
+.BR shutdown (2)
+state.
+.RE
+.TP
+.I udiag_cookie
+This is an array of opaque identifiers that could be used along with
+.I udiag_ino
+to specify an individual socket.
+It is ignored when querying for a list
+of sockets, as well as when all its elements are set to \-1.
+.P
+The response to a query for UNIX domain sockets is represented as an array of
+.P
+.in +4n
+.EX
+struct unix_diag_msg {
+    __u8    udiag_family;
+    __u8    udiag_type;
+    __u8    udiag_state;
+    __u8    pad;
+    __u32   udiag_ino;
+    __u32   udiag_cookie[2];
+};
+.EE
+.in
+.P
+followed by netlink attributes.
+.P
+The fields of this structure are as follows:
+.TP
+.I udiag_family
+This field has the same meaning as in
+.IR "struct unix_diag_req" .
+.TP
+.I udiag_type
+This is set to one of
+.BR SOCK_PACKET ,
+.BR SOCK_STREAM ,
+or
+.BR SOCK_SEQPACKET .
+.TP
+.I udiag_state
+This is set to one of
+.B TCP_LISTEN
+or
+.BR TCP_ESTABLISHED .
+.TP
+.I pad
+This field is set to 0.
+.TP
+.I udiag_ino
+This is the socket inode number.
+.TP
+.I udiag_cookie
+This is an array of opaque identifiers that could be used in subsequent
+queries.
+.\"
+.SS IPv4 and IPv6 sockets
+For IPv4 and IPv6 sockets,
+the request is represented in the following structure:
+.P
+.in +4n
+.EX
+struct inet_diag_req_v2 {
+    __u8    sdiag_family;
+    __u8    sdiag_protocol;
+    __u8    idiag_ext;
+    __u8    pad;
+    __u32   idiag_states;
+    struct inet_diag_sockid id;
+};
+.EE
+.in
+.P
+where
+.I "struct inet_diag_sockid"
+is defined as follows:
+.P
+.in +4n
+.EX
+struct inet_diag_sockid {
+    __be16  idiag_sport;
+    __be16  idiag_dport;
+    __be32  idiag_src[4];
+    __be32  idiag_dst[4];
+    __u32   idiag_if;
+    __u32   idiag_cookie[2];
+};
+.EE
+.in
+.P
+The fields of
+.I "struct inet_diag_req_v2"
+are as follows:
+.TP
+.I sdiag_family
+This should be set to either
+.B AF_INET
+or
+.B AF_INET6
+for IPv4 or IPv6 sockets respectively.
+.TP
+.I sdiag_protocol
+This should be set to one of
+.BR IPPROTO_TCP ,
+.BR IPPROTO_UDP ,
+or
+.BR IPPROTO_UDPLITE .
+.TP
+.I idiag_ext
+This is a set of flags defining what kind of extended information to report.
+Each requested kind of information is reported back as a netlink attribute
+as described below:
+.RS
+.TP
+.B INET_DIAG_TOS
+The payload associated with this attribute is a __u8 value
+which is the TOS of the socket.
+.TP
+.B INET_DIAG_TCLASS
+The payload associated with this attribute is a __u8 value
+which is the TClass of the socket.
+IPv6 sockets only.
+For LISTEN and CLOSE sockets, this is followed by
+.B INET_DIAG_SKV6ONLY
+attribute with associated __u8 payload value meaning whether the socket
+is IPv6-only or not.
+.TP
+.B INET_DIAG_MEMINFO
+The payload associated with this attribute is represented in the following
+structure:
+.IP
+.in +4n
+.EX
+struct inet_diag_meminfo {
+    __u32 idiag_rmem;
+    __u32 idiag_wmem;
+    __u32 idiag_fmem;
+    __u32 idiag_tmem;
+};
+.EE
+.in
+.IP
+The fields of this structure are as follows:
+.RS
+.TP 12
+.I idiag_rmem
+The amount of data in the receive queue.
+.TP
+.I idiag_wmem
+The amount of data that is queued by TCP but not yet sent.
+.TP
+.I idiag_fmem
+The amount of memory scheduled for future use (TCP only).
+.TP
+.I idiag_tmem
+The amount of data in send queue.
+.RE
+.TP
+.B INET_DIAG_SKMEMINFO
+The payload associated with this attribute is an array of __u32 values
+described below in the subsection "Socket memory information".
+.TP
+.B INET_DIAG_INFO
+The payload associated with this attribute is specific to the address family.
+For TCP sockets, it is an object of type
+.IR "struct tcp_info" .
+.TP
+.B INET_DIAG_CONG
+The payload associated with this attribute is a string that describes the
+congestion control algorithm used.
+For TCP sockets only.
+.RE
+.TP
+.I pad
+This should be set to 0.
+.TP
+.I idiag_states
+This is a bit mask that defines a filter of socket states.
+Only those sockets whose states are in this mask will be reported.
+Ignored when querying for an individual socket.
+.TP
+.I id
+This is a socket ID object that is used in dump requests, in queries
+about individual sockets, and is reported back in each response.
+Unlike UNIX domain sockets, IPv4 and IPv6 sockets are identified
+using addresses and ports.
+All values are in network byte order.
+.P
+The fields of
+.I "struct inet_diag_sockid"
+are as follows:
+.TP
+.I idiag_sport
+The source port.
+.TP
+.I idiag_dport
+The destination port.
+.TP
+.I idiag_src
+The source address.
+.TP
+.I idiag_dst
+The destination address.
+.TP
+.I idiag_if
+The interface number the socket is bound to.
+.TP
+.I idiag_cookie
+This is an array of opaque identifiers that could be used along with
+other fields of this structure to specify an individual socket.
+It is ignored when querying for a list of sockets, as well as
+when all its elements are set to \-1.
+.P
+The response to a query for IPv4 or IPv6 sockets is represented as an array of
+.P
+.in +4n
+.EX
+struct inet_diag_msg {
+    __u8    idiag_family;
+    __u8    idiag_state;
+    __u8    idiag_timer;
+    __u8    idiag_retrans;
+\&
+    struct inet_diag_sockid id;
+\&
+    __u32   idiag_expires;
+    __u32   idiag_rqueue;
+    __u32   idiag_wqueue;
+    __u32   idiag_uid;
+    __u32   idiag_inode;
+};
+.EE
+.in
+.P
+followed by netlink attributes.
+.P
+The fields of this structure are as follows:
+.TP
+.I idiag_family
+This is the same field as in
+.IR "struct inet_diag_req_v2" .
+.TP
+.I idiag_state
+This denotes socket state as in
+.IR "struct inet_diag_req_v2" .
+.TP
+.I idiag_timer
+For TCP sockets, this field describes the type of timer that is currently
+active for the socket.
+It is set to one of the following constants:
+.IP
+.PD 0
+.RS 12
+.TP
+.B 0
+no timer is active
+.TP
+.B 1
+a retransmit timer
+.TP
+.B 2
+a keep-alive timer
+.TP
+.B 3
+a TIME_WAIT timer
+.TP
+.B 4
+a zero window probe timer
+.RE
+.PD
+.IP
+For non-TCP sockets, this field is set to 0.
+.TP
+.I idiag_retrans
+For
+.I idiag_timer
+values 1, 2, and 4, this field contains the number of retransmits.
+For other
+.I idiag_timer
+values, this field is set to 0.
+.TP
+.I idiag_expires
+For TCP sockets that have an active timer, this field describes its expiration
+time in milliseconds.
+For other sockets, this field is set to 0.
+.TP
+.I idiag_rqueue
+For listening sockets:
+the number of pending connections.
+.IP
+For other sockets:
+the amount of data in the incoming queue.
+.TP
+.I idiag_wqueue
+For listening sockets:
+the backlog length.
+.IP
+For other sockets:
+the amount of memory available for sending.
+.TP
+.I idiag_uid
+This is the socket owner UID.
+.TP
+.I idiag_inode
+This is the socket inode number.
+.\"
+.SS Socket memory information
+The payload associated with
+.B UNIX_DIAG_MEMINFO
+and
+.B INET_DIAG_SKMEMINFO
+netlink attributes is an array of the following __u32 values:
+.TP
+.B SK_MEMINFO_RMEM_ALLOC
+The amount of data in receive queue.
+.TP
+.B SK_MEMINFO_RCVBUF
+The receive socket buffer as set by
+.BR SO_RCVBUF .
+.TP
+.B SK_MEMINFO_WMEM_ALLOC
+The amount of data in send queue.
+.TP
+.B SK_MEMINFO_SNDBUF
+The send socket buffer as set by
+.BR SO_SNDBUF .
+.TP
+.B SK_MEMINFO_FWD_ALLOC
+The amount of memory scheduled for future use (TCP only).
+.TP
+.B SK_MEMINFO_WMEM_QUEUED
+The amount of data queued by TCP, but not yet sent.
+.TP
+.B SK_MEMINFO_OPTMEM
+The amount of memory allocated for the socket's service needs (e.g., socket
+filter).
+.TP
+.B SK_MEMINFO_BACKLOG
+The amount of packets in the backlog (not yet processed).
+.SH VERSIONS
+.B NETLINK_INET_DIAG
+was introduced in Linux 2.6.14 and supported
+.B AF_INET
+and
+.B AF_INET6
+sockets only.
+In Linux 3.3, it was renamed to
+.B NETLINK_SOCK_DIAG
+and extended to support
+.B AF_UNIX
+sockets.
+.P
+.B UNIX_DIAG_MEMINFO
+and
+.B INET_DIAG_SKMEMINFO
+were introduced in Linux 3.6.
+.SH STANDARDS
+Linux.
+.SH EXAMPLES
+The following example program prints inode number, peer's inode number,
+and name of all UNIX domain sockets in the current namespace.
+.P
+.EX
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/sock_diag.h>
+#include <linux/unix_diag.h>
+\&
+static int
+send_query(int fd)
+{
+    struct sockaddr_nl nladdr = {
+        .nl_family = AF_NETLINK
+    };
+    struct
+    {
+        struct nlmsghdr nlh;
+        struct unix_diag_req udr;
+    } req = {
+        .nlh = {
+            .nlmsg_len = sizeof(req),
+            .nlmsg_type = SOCK_DIAG_BY_FAMILY,
+            .nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP
+        },
+        .udr = {
+            .sdiag_family = AF_UNIX,
+            .udiag_states = \-1,
+            .udiag_show = UDIAG_SHOW_NAME | UDIAG_SHOW_PEER
+        }
+    };
+    struct iovec iov = {
+        .iov_base = &req,
+        .iov_len = sizeof(req)
+    };
+    struct msghdr msg = {
+        .msg_name = &nladdr,
+        .msg_namelen = sizeof(nladdr),
+        .msg_iov = &iov,
+        .msg_iovlen = 1
+    };
+\&
+    for (;;) {
+        if (sendmsg(fd, &msg, 0) < 0) {
+            if (errno == EINTR)
+                continue;
+\&
+            perror("sendmsg");
+            return \-1;
+        }
+\&
+        return 0;
+    }
+}
+\&
+static int
+print_diag(const struct unix_diag_msg *diag, unsigned int len)
+{
+    if (len < NLMSG_LENGTH(sizeof(*diag))) {
+        fputs("short response\en", stderr);
+        return \-1;
+    }
+    if (diag\->udiag_family != AF_UNIX) {
+        fprintf(stderr, "unexpected family %u\en", diag\->udiag_family);
+        return \-1;
+    }
+\&
+    unsigned int rta_len = len \- NLMSG_LENGTH(sizeof(*diag));
+    unsigned int peer = 0;
+    size_t path_len = 0;
+    char path[sizeof(((struct sockaddr_un *) 0)\->sun_path) + 1];
+\&
+    for (struct rtattr *attr = (struct rtattr *) (diag + 1);
+             RTA_OK(attr, rta_len); attr = RTA_NEXT(attr, rta_len)) {
+        switch (attr\->rta_type) {
+        case UNIX_DIAG_NAME:
+            if (!path_len) {
+                path_len = RTA_PAYLOAD(attr);
+                if (path_len > sizeof(path) \- 1)
+                    path_len = sizeof(path) \- 1;
+                memcpy(path, RTA_DATA(attr), path_len);
+                path[path_len] = \[aq]\e0\[aq];
+            }
+            break;
+\&
+        case UNIX_DIAG_PEER:
+            if (RTA_PAYLOAD(attr) >= sizeof(peer))
+                peer = *(unsigned int *) RTA_DATA(attr);
+            break;
+        }
+    }
+\&
+    printf("inode=%u", diag\->udiag_ino);
+\&
+    if (peer)
+        printf(", peer=%u", peer);
+\&
+    if (path_len)
+        printf(", name=%s%s", *path ? "" : "@",
+                *path ? path : path + 1);
+\&
+    putchar(\[aq]\en\[aq]);
+    return 0;
+}
+\&
+static int
+receive_responses(int fd)
+{
+    long buf[8192 / sizeof(long)];
+    struct sockaddr_nl nladdr;
+    struct iovec iov = {
+        .iov_base = buf,
+        .iov_len = sizeof(buf)
+    };
+    int flags = 0;
+\&
+    for (;;) {
+        struct msghdr msg = {
+            .msg_name = &nladdr,
+            .msg_namelen = sizeof(nladdr),
+            .msg_iov = &iov,
+            .msg_iovlen = 1
+        };
+\&
+        ssize_t ret = recvmsg(fd, &msg, flags);
+\&
+        if (ret < 0) {
+            if (errno == EINTR)
+                continue;
+\&
+            perror("recvmsg");
+            return \-1;
+        }
+        if (ret == 0)
+            return 0;
+\&
+        if (nladdr.nl_family != AF_NETLINK) {
+            fputs("!AF_NETLINK\en", stderr);
+            return \-1;
+        }
+\&
+        const struct nlmsghdr *h = (struct nlmsghdr *) buf;
+\&
+        if (!NLMSG_OK(h, ret)) {
+            fputs("!NLMSG_OK\en", stderr);
+            return \-1;
+        }
+\&
+        for (; NLMSG_OK(h, ret); h = NLMSG_NEXT(h, ret)) {
+            if (h\->nlmsg_type == NLMSG_DONE)
+                return 0;
+\&
+            if (h\->nlmsg_type == NLMSG_ERROR) {
+                const struct nlmsgerr *err = NLMSG_DATA(h);
+\&
+                if (h\->nlmsg_len < NLMSG_LENGTH(sizeof(*err))) {
+                    fputs("NLMSG_ERROR\en", stderr);
+                } else {
+                    errno = \-err\->error;
+                    perror("NLMSG_ERROR");
+                }
+\&
+                return \-1;
+            }
+\&
+            if (h\->nlmsg_type != SOCK_DIAG_BY_FAMILY) {
+                fprintf(stderr, "unexpected nlmsg_type %u\en",
+                        (unsigned) h\->nlmsg_type);
+                return \-1;
+            }
+\&
+            if (print_diag(NLMSG_DATA(h), h\->nlmsg_len))
+                return \-1;
+        }
+    }
+}
+\&
+int
+main(void)
+{
+    int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
+\&
+    if (fd < 0) {
+        perror("socket");
+        return 1;
+    }
+\&
+    int ret = send_query(fd) || receive_responses(fd);
+\&
+    close(fd);
+    return ret;
+}
+.EE
+.SH SEE ALSO
+.BR netlink (3),
+.BR rtnetlink (3),
+.BR netlink (7),
+.BR tcp (7)
diff --git a/man/man7/socket.7 b/man/man7/socket.7
new file mode 100644
index 000000000..3ebfc770b
--- /dev/null
+++ b/man/man7/socket.7
@@ -0,0 +1,1274 @@
+'\" t
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\" and copyright (c) 1999 Matthew Wilcox.
+.\"
+.\" 2002-10-30, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"	Added description of SO_ACCEPTCONN
+.\" 2004-05-20, aeb, added SO_RCVTIMEO/SO_SNDTIMEO text.
+.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"     Added notes on capability requirements
+.\"	A few small grammar fixes
+.\" 2010-06-13 Jan Engelhardt <jengelh@medozas.de>
+.\"	Documented SO_DOMAIN and SO_PROTOCOL.
+.\"
+.\" FIXME
+.\" The following are not yet documented:
+.\"
+.\" SO_PEERNAME (2.4?)
+.\"	get only
+.\"	Seems to do something similar to getpeername(), but then
+.\"	why is it necessary / how does it differ?
+.\"
+.\" SO_TIMESTAMPING (2.6.30)
+.\"	Documentation/networking/timestamping.txt
+.\"	commit cb9eff097831007afb30d64373f29d99825d0068
+.\"	Author: Patrick Ohly <patrick.ohly@intel.com>
+.\"
+.\"  SO_WIFI_STATUS (3.3)
+.\"	commit 6e3e939f3b1bf8534b32ad09ff199d88800835a0
+.\"	Author: Johannes Berg <johannes.berg@intel.com>
+.\"	Also: SCM_WIFI_STATUS
+.\"
+.\" SO_NOFCS (3.4)
+.\"	commit 3bdc0eba0b8b47797f4a76e377dd8360f317450f
+.\"	Author: Ben Greear <greearb@candelatech.com>
+.\"
+.\"  SO_GET_FILTER (3.8)
+.\"	commit a8fc92778080c845eaadc369a0ecf5699a03bef0
+.\"	Author: Pavel Emelyanov <xemul@parallels.com>
+.\"
+.\" SO_MAX_PACING_RATE (3.13)
+.\"	commit 62748f32d501f5d3712a7c372bbb92abc7c62bc7
+.\"	Author: Eric Dumazet <edumazet@google.com>
+.\"
+.\" SO_BPF_EXTENSIONS (3.14)
+.\"	commit ea02f9411d9faa3553ed09ce0ec9f00ceae9885e
+.\"	Author: Michal Sekletar <msekleta@redhat.com>
+.\"
+.TH socket 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+socket \- Linux socket interface
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.P
+.IB sockfd " = socket(int " socket_family ", int " socket_type ", int " protocol );
+.fi
+.SH DESCRIPTION
+This manual page describes the Linux networking socket layer user
+interface.
+The BSD compatible sockets
+are the uniform interface
+between the user process and the network protocol stacks in the kernel.
+The protocol modules are grouped into
+.I protocol families
+such as
+.BR AF_INET ", " AF_IPX ", and " AF_PACKET ,
+and
+.I socket types
+such as
+.B SOCK_STREAM
+or
+.BR SOCK_DGRAM .
+See
+.BR socket (2)
+for more information on families and types.
+.SS Socket-layer functions
+These functions are used by the user process to send or receive packets
+and to do other socket operations.
+For more information, see their respective manual pages.
+.P
+.BR socket (2)
+creates a socket,
+.BR connect (2)
+connects a socket to a remote socket address,
+the
+.BR bind (2)
+function binds a socket to a local socket address,
+.BR listen (2)
+tells the socket that new connections shall be accepted, and
+.BR accept (2)
+is used to get a new socket with a new incoming connection.
+.BR socketpair (2)
+returns two connected anonymous sockets (implemented only for a few
+local families like
+.BR AF_UNIX )
+.P
+.BR send (2),
+.BR sendto (2),
+and
+.BR sendmsg (2)
+send data over a socket, and
+.BR recv (2),
+.BR recvfrom (2),
+.BR recvmsg (2)
+receive data from a socket.
+.BR poll (2)
+and
+.BR select (2)
+wait for arriving data or a readiness to send data.
+In addition, the standard I/O operations like
+.BR write (2),
+.BR writev (2),
+.BR sendfile (2),
+.BR read (2),
+and
+.BR readv (2)
+can be used to read and write data.
+.P
+.BR getsockname (2)
+returns the local socket address and
+.BR getpeername (2)
+returns the remote socket address.
+.BR getsockopt (2)
+and
+.BR setsockopt (2)
+are used to set or get socket layer or protocol options.
+.BR ioctl (2)
+can be used to set or read some other options.
+.P
+.BR close (2)
+is used to close a socket.
+.BR shutdown (2)
+closes parts of a full-duplex socket connection.
+.P
+Seeking, or calling
+.BR pread (2)
+or
+.BR pwrite (2)
+with a nonzero position is not supported on sockets.
+.P
+It is possible to do nonblocking I/O on sockets by setting the
+.B O_NONBLOCK
+flag on a socket file descriptor using
+.BR fcntl (2).
+Then all operations that would block will (usually)
+return with
+.B EAGAIN
+(operation should be retried later);
+.BR connect (2)
+will return
+.B EINPROGRESS
+error.
+The user can then wait for various events via
+.BR poll (2)
+or
+.BR select (2).
+.TS
+tab(:) allbox;
+c s s
+l l lx.
+I/O events
+Event:Poll flag:Occurrence
+Read:POLLIN:T{
+New data arrived.
+T}
+Read:POLLIN:T{
+A connection setup has been completed
+(for connection-oriented sockets)
+T}
+Read:POLLHUP:T{
+A disconnection request has been initiated by the other end.
+T}
+Read:POLLHUP:T{
+A connection is broken (only for connection-oriented protocols).
+When the socket is written
+.B SIGPIPE
+is also sent.
+T}
+Write:POLLOUT:T{
+Socket has enough send buffer space for writing new data.
+T}
+Read/Write:T{
+POLLIN |
+.br
+POLLOUT
+T}:T{
+An outgoing
+.BR connect (2)
+finished.
+T}
+Read/Write:POLLERR:T{
+An asynchronous error occurred.
+T}
+Read/Write:POLLHUP:T{
+The other end has shut down one direction.
+T}
+Exception:POLLPRI:T{
+Urgent data arrived.
+.B SIGURG
+is sent then.
+T}
+.\" FIXME . The following is not true currently:
+.\" It is no I/O event when the connection
+.\" is broken from the local end using
+.\" .BR shutdown (2)
+.\" or
+.\" .BR close (2).
+.TE
+.P
+An alternative to
+.BR poll (2)
+and
+.BR select (2)
+is to let the kernel inform the application about events
+via a
+.B SIGIO
+signal.
+For that the
+.B O_ASYNC
+flag must be set on a socket file descriptor via
+.BR fcntl (2)
+and a valid signal handler for
+.B SIGIO
+must be installed via
+.BR sigaction (2).
+See the
+.I Signals
+discussion below.
+.SS Socket address structures
+Each socket domain has its own format for socket addresses,
+with a domain-specific address structure.
+Each of these structures begins with an
+integer "family" field (typed as
+.IR sa_family_t )
+that indicates the type of the address structure.
+This allows
+the various system calls (e.g.,
+.BR connect (2),
+.BR bind (2),
+.BR accept (2),
+.BR getsockname (2),
+.BR getpeername (2)),
+which are generic to all socket domains,
+to determine the domain of a particular socket address.
+.P
+To allow any type of socket address to be passed to
+interfaces in the sockets API,
+the type
+.I struct sockaddr
+is defined.
+The purpose of this type is purely to allow casting of
+domain-specific socket address types to a "generic" type,
+so as to avoid compiler warnings about type mismatches in
+calls to the sockets API.
+.P
+In addition, the sockets API provides the data type
+.IR "struct sockaddr_storage".
+This type
+is suitable to accommodate all supported domain-specific socket
+address structures; it is large enough and is aligned properly.
+(In particular, it is large enough to hold
+IPv6 socket addresses.)
+The structure includes the following field, which can be used to identify
+the type of socket address actually stored in the structure:
+.P
+.in +4n
+.EX
+    sa_family_t ss_family;
+.EE
+.in
+.P
+The
+.I sockaddr_storage
+structure is useful in programs that must handle socket addresses
+in a generic way
+(e.g., programs that must deal with both IPv4 and IPv6 socket addresses).
+.SS Socket options
+The socket options listed below can be set by using
+.BR setsockopt (2)
+and read with
+.BR getsockopt (2)
+with the socket level set to
+.B SOL_SOCKET
+for all sockets.
+Unless otherwise noted,
+.I optval
+is a pointer to an
+.IR int .
+.\" FIXME .
+.\" In the list below, the text used to describe argument types
+.\" for each socket option should be more consistent
+.\"
+.\" SO_ACCEPTCONN is in POSIX.1-2001, and its origin is explained in
+.\" W R Stevens, UNPv1
+.TP
+.B SO_ACCEPTCONN
+Returns a value indicating whether or not this socket has been marked
+to accept connections with
+.BR listen (2).
+The value 0 indicates that this is not a listening socket,
+the value 1 indicates that this is a listening socket.
+This socket option is read-only.
+.TP
+.BR SO_ATTACH_FILTER " (since Linux 2.2)"
+.TQ
+.BR SO_ATTACH_BPF " (since Linux 3.19)"
+Attach a classic BPF
+.RB ( SO_ATTACH_FILTER )
+or an extended BPF
+.RB ( SO_ATTACH_BPF )
+program to the socket for use as a filter of incoming packets.
+A packet will be dropped if the filter program returns zero.
+If the filter program returns a
+nonzero value which is less than the packet's data length,
+the packet will be truncated to the length returned.
+If the value returned by the filter is greater than or equal to the
+packet's data length, the packet is allowed to proceed unmodified.
+.IP
+The argument for
+.B SO_ATTACH_FILTER
+is a
+.I sock_fprog
+structure, defined in
+.IR <linux/filter.h> :
+.IP
+.in +4n
+.EX
+struct sock_fprog {
+    unsigned short      len;
+    struct sock_filter *filter;
+};
+.EE
+.in
+.IP
+The argument for
+.B SO_ATTACH_BPF
+is a file descriptor returned by the
+.BR bpf (2)
+system call and must refer to a program of type
+.BR BPF_PROG_TYPE_SOCKET_FILTER .
+.IP
+These options may be set multiple times for a given socket,
+each time replacing the previous filter program.
+The classic and extended versions may be called on the same socket,
+but the previous filter will always be replaced such that a socket
+never has more than one filter defined.
+.IP
+Both classic and extended BPF are explained in the kernel source file
+.I Documentation/networking/filter.txt
+.TP
+.B SO_ATTACH_REUSEPORT_CBPF
+.TQ
+.B SO_ATTACH_REUSEPORT_EBPF
+For use with the
+.B SO_REUSEPORT
+option, these options allow the user to set a classic BPF
+.RB ( SO_ATTACH_REUSEPORT_CBPF )
+or an extended BPF
+.RB ( SO_ATTACH_REUSEPORT_EBPF )
+program which defines how packets are assigned to
+the sockets in the reuseport group (that is, all sockets which have
+.B SO_REUSEPORT
+set and are using the same local address to receive packets).
+.IP
+The BPF program must return an index between 0 and N\-1 representing
+the socket which should receive the packet
+(where N is the number of sockets in the group).
+If the BPF program returns an invalid index,
+socket selection will fall back to the plain
+.B SO_REUSEPORT
+mechanism.
+.IP
+Sockets are numbered in the order in which they are added to the group
+(that is, the order of
+.BR bind (2)
+calls for UDP sockets or the order of
+.BR listen (2)
+calls for TCP sockets).
+New sockets added to a reuseport group will inherit the BPF program.
+When a socket is removed from a reuseport group (via
+.BR close (2)),
+the last socket in the group will be moved into the closed socket's
+position.
+.IP
+These options may be set repeatedly at any time on any socket in the group
+to replace the current BPF program used by all sockets in the group.
+.IP
+.B SO_ATTACH_REUSEPORT_CBPF
+takes the same argument type as
+.B SO_ATTACH_FILTER
+and
+.B SO_ATTACH_REUSEPORT_EBPF
+takes the same argument type as
+.BR SO_ATTACH_BPF .
+.IP
+UDP support for this feature is available since Linux 4.5;
+TCP support is available since Linux 4.6.
+.TP
+.B SO_BINDTODEVICE
+Bind this socket to a particular device like \[lq]eth0\[rq],
+as specified in the passed interface name.
+If the
+name is an empty string or the option length is zero, the socket device
+binding is removed.
+The passed option is a variable-length null-terminated
+interface name string with the maximum size of
+.BR IFNAMSIZ .
+If a socket is bound to an interface,
+only packets received from that particular interface are processed by the
+socket.
+Note that this works only for some socket types, particularly
+.B AF_INET
+sockets.
+It is not supported for packet sockets (use normal
+.BR bind (2)
+there).
+.IP
+Before Linux 3.8,
+this socket option could be set, but could not retrieved with
+.BR getsockopt (2).
+Since Linux 3.8, it is readable.
+The
+.I optlen
+argument should contain the buffer size available
+to receive the device name and is recommended to be
+.B IFNAMSIZ
+bytes.
+The real device name length is reported back in the
+.I optlen
+argument.
+.TP
+.B SO_BROADCAST
+Set or get the broadcast flag.
+When enabled, datagram sockets are allowed to send
+packets to a broadcast address.
+This option has no effect on stream-oriented sockets.
+.TP
+.B SO_BSDCOMPAT
+Enable BSD bug-to-bug compatibility.
+This is used by the UDP protocol module in Linux 2.0 and 2.2.
+If enabled, ICMP errors received for a UDP socket will not be passed
+to the user program.
+In later kernel versions, support for this option has been phased out:
+Linux 2.4 silently ignores it, and Linux 2.6 generates a kernel warning
+(printk()) if a program uses this option.
+Linux 2.0 also enabled BSD bug-to-bug compatibility
+options (random header changing, skipping of the broadcast flag) for raw
+sockets with this option, but that was removed in Linux 2.2.
+.TP
+.B SO_DEBUG
+Enable socket debugging.
+Allowed only for processes with the
+.B CAP_NET_ADMIN
+capability or an effective user ID of 0.
+.TP
+.BR SO_DETACH_FILTER " (since Linux 2.2)"
+.TQ
+.BR SO_DETACH_BPF " (since Linux 3.19)"
+These two options, which are synonyms,
+may be used to remove the classic or extended BPF
+program attached to a socket with either
+.B SO_ATTACH_FILTER
+or
+.BR SO_ATTACH_BPF .
+The option value is ignored.
+.TP
+.BR SO_DOMAIN " (since Linux 2.6.32)"
+Retrieves the socket domain as an integer, returning a value such as
+.BR AF_INET6 .
+See
+.BR socket (2)
+for details.
+This socket option is read-only.
+.TP
+.B SO_ERROR
+Get and clear the pending socket error.
+This socket option is read-only.
+Expects an integer.
+.TP
+.B SO_DONTROUTE
+Don't send via a gateway, send only to directly connected hosts.
+The same effect can be achieved by setting the
+.B MSG_DONTROUTE
+flag on a socket
+.BR send (2)
+operation.
+Expects an integer boolean flag.
+.TP
+.BR SO_INCOMING_CPU " (gettable since Linux 3.19, settable since Linux 4.4)"
+.\" getsockopt 2c8c56e15df3d4c2af3d656e44feb18789f75837
+.\" setsockopt 70da268b569d32a9fddeea85dc18043de9d89f89
+Sets or gets the CPU affinity of a socket.
+Expects an integer flag.
+.IP
+.in +4n
+.EX
+int cpu = 1;
+setsockopt(fd, SOL_SOCKET, SO_INCOMING_CPU, &cpu,
+           sizeof(cpu));
+.EE
+.in
+.IP
+Because all of the packets for a single stream
+(i.e., all packets for the same 4-tuple)
+arrive on the single RX queue that is associated with a particular CPU,
+the typical use case is to employ one listening process per RX queue,
+with the incoming flow being handled by a listener
+on the same CPU that is handling the RX queue.
+This provides optimal NUMA behavior and keeps CPU caches hot.
+.\"
+.\" From an email conversation with Eric Dumazet:
+.\" >> Note that setting the option is not supported if SO_REUSEPORT is used.
+.\" >
+.\" > Please define "not supported". Does this yield an API diagnostic?
+.\" > If so, what is it?
+.\" >
+.\" >> Socket will be selected from an array, either by a hash or BPF program
+.\" >> that has no access to this information.
+.\" >
+.\" > Sorry -- I'm lost here. How does this comment relate to the proposed
+.\" > man page text above?
+.\"
+.\" Simply that :
+.\"
+.\" If an application uses both SO_INCOMING_CPU and SO_REUSEPORT, then
+.\" SO_REUSEPORT logic, selecting the socket to receive the packet, ignores
+.\" SO_INCOMING_CPU setting.
+.TP
+.BR SO_INCOMING_NAPI_ID " (gettable since Linux 4.12)"
+.\" getsockopt 6d4339028b350efbf87c61e6d9e113e5373545c9
+Returns a system-level unique ID called NAPI ID that is associated
+with a RX queue on which the last packet associated with that
+socket is received.
+.IP
+This can be used by an application to split the incoming flows among worker
+threads based on the RX queue on which the packets associated with the
+flows are received.
+It allows each worker thread to be associated with
+a NIC HW receive queue and service all the connection
+requests received on that RX queue.
+This mapping between an app thread and
+a HW NIC queue streamlines the
+flow of data from the NIC to the application.
+.TP
+.B SO_KEEPALIVE
+Enable sending of keep-alive messages on connection-oriented sockets.
+Expects an integer boolean flag.
+.TP
+.B SO_LINGER
+Sets or gets the
+.B SO_LINGER
+option.
+The argument is a
+.I linger
+structure.
+.IP
+.in +4n
+.EX
+struct linger {
+    int l_onoff;    /* linger active */
+    int l_linger;   /* how many seconds to linger for */
+};
+.EE
+.in
+.IP
+When enabled, a
+.BR close (2)
+or
+.BR shutdown (2)
+will not return until all queued messages for the socket have been
+successfully sent or the linger timeout has been reached.
+Otherwise,
+the call returns immediately and the closing is done in the background.
+When the socket is closed as part of
+.BR exit (2),
+it always lingers in the background.
+.TP
+.B SO_LOCK_FILTER
+.\" commit d59577b6ffd313d0ab3be39cb1ab47e29bdc9182
+When set, this option will prevent
+changing the filters associated with the socket.
+These filters include any set using the socket options
+.BR SO_ATTACH_FILTER ,
+.BR SO_ATTACH_BPF ,
+.BR SO_ATTACH_REUSEPORT_CBPF ,
+and
+.BR SO_ATTACH_REUSEPORT_EBPF .
+.IP
+The typical use case is for a privileged process to set up a raw socket
+(an operation that requires the
+.B CAP_NET_RAW
+capability), apply a restrictive filter, set the
+.B SO_LOCK_FILTER
+option,
+and then either drop its privileges or pass the socket file descriptor
+to an unprivileged process via a UNIX domain socket.
+.IP
+Once the
+.B SO_LOCK_FILTER
+option has been enabled, attempts to change or remove the filter
+attached to a socket, or to disable the
+.B SO_LOCK_FILTER
+option will fail with the error
+.BR EPERM .
+.TP
+.BR SO_MARK " (since Linux 2.6.25)"
+.\" commit 4a19ec5800fc3bb64e2d87c4d9fdd9e636086fe0
+.\" and    914a9ab386a288d0f22252fc268ecbc048cdcbd5
+Set the mark for each packet sent through this socket
+(similar to the netfilter MARK target but socket-based).
+Changing the mark can be used for mark-based
+routing without netfilter or for packet filtering.
+Setting this option requires the
+.B CAP_NET_ADMIN
+or
+.B CAP_NET_RAW
+(since Linux 5.17) capability.
+.TP
+.B SO_OOBINLINE
+If this option is enabled,
+out-of-band data is directly placed into the receive data stream.
+Otherwise, out-of-band data is passed only when the
+.B MSG_OOB
+flag is set during receiving.
+.\" don't document it because it can do too much harm.
+.\".B SO_NO_CHECK
+.\"     The kernel has support for the SO_NO_CHECK socket
+.\"     option (boolean: 0 == default, calculate checksum on xmit,
+.\"     1 == do not calculate checksum on xmit).
+.\" Additional note from Andi Kleen on SO_NO_CHECK (2010-08-30)
+.\"     On Linux UDP checksums are essentially free and there's no reason
+.\"     to turn them off and it would disable another safety line.
+.\"     That is why I didn't document the option.
+.TP
+.B SO_PASSCRED
+Enable or disable the receiving of the
+.B SCM_CREDENTIALS
+control message.
+For more information, see
+.BR unix (7).
+.TP
+.B SO_PASSSEC
+Enable or disable the receiving of the
+.B SCM_SECURITY
+control message.
+For more information, see
+.BR unix (7).
+.TP
+.BR SO_PEEK_OFF " (since Linux 3.4)"
+.\" commit ef64a54f6e558155b4f149bb10666b9e914b6c54
+This option, which is currently supported only for
+.BR unix (7)
+sockets, sets the value of the "peek offset" for the
+.BR recv (2)
+system call when used with
+.B MSG_PEEK
+flag.
+.IP
+When this option is set to a negative value
+(it is set to \-1 for all new sockets),
+traditional behavior is provided:
+.BR recv (2)
+with the
+.B MSG_PEEK
+flag will peek data from the front of the queue.
+.IP
+When the option is set to a value greater than or equal to zero,
+then the next peek at data queued in the socket will occur at
+the byte offset specified by the option value.
+At the same time, the "peek offset" will be
+incremented by the number of bytes that were peeked from the queue,
+so that a subsequent peek will return the next data in the queue.
+.IP
+If data is removed from the front of the queue via a call to
+.BR recv (2)
+(or similar) without the
+.B MSG_PEEK
+flag, the "peek offset" will be decreased by the number of bytes removed.
+In other words, receiving data without the
+.B MSG_PEEK
+flag will cause the "peek offset" to be adjusted to maintain
+the correct relative position in the queued data,
+so that a subsequent peek will retrieve the data that would have been
+retrieved had the data not been removed.
+.IP
+For datagram sockets, if the "peek offset" points to the middle of a packet,
+the data returned will be marked with the
+.B MSG_TRUNC
+flag.
+.IP
+The following example serves to illustrate the use of
+.BR SO_PEEK_OFF .
+Suppose a stream socket has the following queued input data:
+.IP
+.in +4n
+.EX
+aabbccddeeff
+.EE
+.in
+.IP
+The following sequence of
+.BR recv (2)
+calls would have the effect noted in the comments:
+.IP
+.in +4n
+.EX
+int ov = 4;                  // Set peek offset to 4
+setsockopt(fd, SOL_SOCKET, SO_PEEK_OFF, &ov, sizeof(ov));
+\&
+recv(fd, buf, 2, MSG_PEEK);  // Peeks "cc"; offset set to 6
+recv(fd, buf, 2, MSG_PEEK);  // Peeks "dd"; offset set to 8
+recv(fd, buf, 2, 0);         // Reads "aa"; offset set to 6
+recv(fd, buf, 2, MSG_PEEK);  // Peeks "ee"; offset set to 8
+.EE
+.in
+.TP
+.B SO_PEERCRED
+Return the credentials of the peer process connected to this socket.
+For further details, see
+.BR unix (7).
+.TP
+.BR SO_PEERSEC " (since Linux 2.6.2)"
+Return the security context of the peer socket connected to this socket.
+For further details, see
+.BR unix (7)
+and
+.BR ip (7).
+.TP
+.B SO_PRIORITY
+Set the protocol-defined priority for all packets to be sent on
+this socket.
+Linux uses this value to order the networking queues:
+packets with a higher priority may be processed first depending
+on the selected device queueing discipline.
+.\" For
+.\" .BR ip (7),
+.\" this also sets the IP type-of-service (TOS) field for outgoing packets.
+Setting a priority outside the range 0 to 6 requires the
+.B CAP_NET_ADMIN
+capability.
+.TP
+.BR SO_PROTOCOL " (since Linux 2.6.32)"
+Retrieves the socket protocol as an integer, returning a value such as
+.BR IPPROTO_SCTP .
+See
+.BR socket (2)
+for details.
+This socket option is read-only.
+.TP
+.B SO_RCVBUF
+Sets or gets the maximum socket receive buffer in bytes.
+The kernel doubles this value (to allow space for bookkeeping overhead)
+when it is set using
+.\" Most (all?) other implementations do not do this -- MTK, Dec 05
+.BR setsockopt (2),
+and this doubled value is returned by
+.BR getsockopt (2).
+.\" The following thread on LMKL is quite informative:
+.\" getsockopt/setsockopt with SO_RCVBUF and SO_SNDBUF "non-standard" behavior
+.\" 17 July 2012
+.\" http://thread.gmane.org/gmane.linux.kernel/1328935
+The default value is set by the
+.I /proc/sys/net/core/rmem_default
+file, and the maximum allowed value is set by the
+.I /proc/sys/net/core/rmem_max
+file.
+The minimum (doubled) value for this option is 256.
+.TP
+.BR SO_RCVBUFFORCE " (since Linux 2.6.14)"
+Using this socket option, a privileged
+.RB ( CAP_NET_ADMIN )
+process can perform the same task as
+.BR SO_RCVBUF ,
+but the
+.I rmem_max
+limit can be overridden.
+.TP
+.BR SO_RCVLOWAT " and " SO_SNDLOWAT
+Specify the minimum number of bytes in the buffer until the socket layer
+will pass the data to the protocol
+.RB ( SO_SNDLOWAT )
+or the user on receiving
+.RB ( SO_RCVLOWAT ).
+These two values are initialized to 1.
+.B SO_SNDLOWAT
+is not changeable on Linux
+.RB ( setsockopt (2)
+fails with the error
+.BR ENOPROTOOPT ).
+.B SO_RCVLOWAT
+is changeable
+only since Linux 2.4.
+.IP
+Before Linux 2.6.28
+.\" Tested on kernel 2.6.14 -- mtk, 30 Nov 05
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7)
+did not respect the
+.B SO_RCVLOWAT
+setting on Linux,
+and indicated a socket as readable when even a single byte of data
+was available.
+A subsequent read from the socket would then block until
+.B SO_RCVLOWAT
+bytes are available.
+Since Linux 2.6.28,
+.\" commit c7004482e8dcb7c3c72666395cfa98a216a4fb70
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7)
+indicate a socket as readable only if at least
+.B SO_RCVLOWAT
+bytes are available.
+.TP
+.BR SO_RCVTIMEO " and " SO_SNDTIMEO
+.\" Not implemented in Linux 2.0.
+.\" Implemented in Linux 2.1.11 for getsockopt: always return a zero struct.
+.\" Implemented in Linux 2.3.41 for setsockopt, and actually used.
+Specify the receiving or sending timeouts until reporting an error.
+The argument is a
+.IR "struct timeval" .
+If an input or output function blocks for this period of time, and
+data has been sent or received, the return value of that function
+will be the amount of data transferred; if no data has been transferred
+and the timeout has been reached, then \-1 is returned with
+.I errno
+set to
+.B EAGAIN
+or
+.BR EWOULDBLOCK ,
+.\" in fact to EAGAIN
+or
+.B EINPROGRESS
+(for
+.BR connect (2))
+just as if the socket was specified to be nonblocking.
+If the timeout is set to zero (the default),
+then the operation will never timeout.
+Timeouts only have effect for system calls that perform socket I/O (e.g.,
+.BR accept (2),
+.BR connect (2),
+.BR read (2),
+.BR recvmsg (2),
+.BR send (2),
+.BR sendmsg (2));
+timeouts have no effect for
+.BR select (2),
+.BR poll (2),
+.BR epoll_wait (2),
+and so on.
+.TP
+.B SO_REUSEADDR
+.\"	commit c617f398edd4db2b8567a28e899a88f8f574798d
+.\"	https://lwn.net/Articles/542629/
+Indicates that the rules used in validating addresses supplied in a
+.BR bind (2)
+call should allow reuse of local addresses.
+For
+.B AF_INET
+sockets this
+means that a socket may bind, except when there
+is an active listening socket bound to the address.
+When the listening socket is bound to
+.B INADDR_ANY
+with a specific port then it is not possible
+to bind to this port for any local address.
+Argument is an integer boolean flag.
+.TP
+.BR SO_REUSEPORT " (since Linux 3.9)"
+Permits multiple
+.B AF_INET
+or
+.B AF_INET6
+sockets to be bound to an identical socket address.
+This option must be set on each socket (including the first socket)
+prior to calling
+.BR bind (2)
+on the socket.
+To prevent port hijacking,
+all of the processes binding to the same address must have the same
+effective UID.
+This option can be employed with both TCP and UDP sockets.
+.IP
+For TCP sockets, this option allows
+.BR accept (2)
+load distribution in a multi-threaded server to be improved by
+using a distinct listener socket for each thread.
+This provides improved load distribution as compared
+to traditional techniques such using a single
+.BR accept (2)ing
+thread that distributes connections,
+or having multiple threads that compete to
+.BR accept (2)
+from the same socket.
+.IP
+For UDP sockets,
+the use of this option can provide better distribution
+of incoming datagrams to multiple processes (or threads) as compared
+to the traditional technique of having multiple processes
+compete to receive datagrams on the same socket.
+.TP
+.BR SO_RXQ_OVFL " (since Linux 2.6.33)"
+.\" commit 3b885787ea4112eaa80945999ea0901bf742707f
+Indicates that an unsigned 32-bit value ancillary message (cmsg)
+should be attached to received skbs indicating
+the number of packets dropped by the socket since its creation.
+.TP
+.BR SO_SELECT_ERR_QUEUE " (since Linux 3.10)"
+.\"	commit 7d4c04fc170087119727119074e72445f2bb192b
+.\"	Author: Keller, Jacob E <jacob.e.keller@intel.com>
+When this option is set on a socket,
+an error condition on a socket causes notification not only via the
+.I exceptfds
+set of
+.BR select (2).
+Similarly,
+.BR poll (2)
+also returns a
+.B POLLPRI
+whenever an
+.B POLLERR
+event is returned.
+.\" It does not affect wake up.
+.IP
+Background: this option was added when waking up on an error condition
+occurred only via the
+.I readfds
+and
+.I writefds
+sets of
+.BR select (2).
+The option was added to allow monitoring for error conditions via the
+.I exceptfds
+argument without simultaneously having to receive notifications (via
+.IR readfds )
+for regular data that can be read from the socket.
+After changes in Linux 4.16,
+.\" commit 6e5d58fdc9bedd0255a8
+.\" ("skbuff: Fix not waking applications when errors are enqueued")
+the use of this flag to achieve the desired notifications
+is no longer necessary.
+This option is nevertheless retained for backwards compatibility.
+.TP
+.B SO_SNDBUF
+Sets or gets the maximum socket send buffer in bytes.
+The kernel doubles this value (to allow space for bookkeeping overhead)
+when it is set using
+.\" Most (all?) other implementations do not do this -- MTK, Dec 05
+.\" See also the comment to SO_RCVBUF (17 Jul 2012 LKML mail)
+.BR setsockopt (2),
+and this doubled value is returned by
+.BR getsockopt (2).
+The default value is set by the
+.I /proc/sys/net/core/wmem_default
+file and the maximum allowed value is set by the
+.I /proc/sys/net/core/wmem_max
+file.
+The minimum (doubled) value for this option is 2048.
+.TP
+.BR SO_SNDBUFFORCE " (since Linux 2.6.14)"
+Using this socket option, a privileged
+.RB ( CAP_NET_ADMIN )
+process can perform the same task as
+.BR SO_SNDBUF ,
+but the
+.I wmem_max
+limit can be overridden.
+.TP
+.B SO_TIMESTAMP
+Enable or disable the receiving of the
+.B SO_TIMESTAMP
+control message.
+The timestamp control message is sent with level
+.B SOL_SOCKET
+and a
+.I cmsg_type
+of
+.BR SCM_TIMESTAMP .
+The
+.I cmsg_data
+field is a
+.I "struct timeval"
+indicating the
+reception time of the last packet passed to the user in this call.
+See
+.BR cmsg (3)
+for details on control messages.
+.TP
+.BR SO_TIMESTAMPNS " (since Linux 2.6.22)"
+.\" commit 92f37fd2ee805aa77925c1e64fd56088b46094fc
+Enable or disable the receiving of the
+.B SO_TIMESTAMPNS
+control message.
+The timestamp control message is sent with level
+.B SOL_SOCKET
+and a
+.I cmsg_type
+of
+.BR SCM_TIMESTAMPNS .
+The
+.I cmsg_data
+field is a
+.I "struct timespec"
+indicating the
+reception time of the last packet passed to the user in this call.
+The clock used for the timestamp is
+.BR CLOCK_REALTIME .
+See
+.BR cmsg (3)
+for details on control messages.
+.IP
+A socket cannot mix
+.B SO_TIMESTAMP
+and
+.BR SO_TIMESTAMPNS :
+the two modes are mutually exclusive.
+.TP
+.B SO_TYPE
+Gets the socket type as an integer (e.g.,
+.BR SOCK_STREAM ).
+This socket option is read-only.
+.TP
+.BR SO_BUSY_POLL " (since Linux 3.11)"
+Sets the approximate time in microseconds to busy poll on a blocking receive
+when there is no data.
+Increasing this value requires
+.BR CAP_NET_ADMIN .
+The default for this option is controlled by the
+.I /proc/sys/net/core/busy_read
+file.
+.IP
+The value in the
+.I /proc/sys/net/core/busy_poll
+file determines how long
+.BR select (2)
+and
+.BR poll (2)
+will busy poll when they operate on sockets with
+.B SO_BUSY_POLL
+set and no events to report are found.
+.IP
+In both cases,
+busy polling will only be done when the socket last received data
+from a network device that supports this option.
+.IP
+While busy polling may improve latency of some applications,
+care must be taken when using it since this will increase
+both CPU utilization and power usage.
+.SS Signals
+When writing onto a connection-oriented socket that has been shut down
+(by the local or the remote end)
+.B SIGPIPE
+is sent to the writing process and
+.B EPIPE
+is returned.
+The signal is not sent when the write call
+specified the
+.B MSG_NOSIGNAL
+flag.
+.P
+When requested with the
+.B FIOSETOWN
+.BR fcntl (2)
+or
+.B SIOCSPGRP
+.BR ioctl (2),
+.B SIGIO
+is sent when an I/O event occurs.
+It is possible to use
+.BR poll (2)
+or
+.BR select (2)
+in the signal handler to find out which socket the event occurred on.
+An alternative (in Linux 2.2) is to set a real-time signal using the
+.B F_SETSIG
+.BR fcntl (2);
+the handler of the real time signal will be called with
+the file descriptor in the
+.I si_fd
+field of its
+.IR siginfo_t .
+See
+.BR fcntl (2)
+for more information.
+.P
+Under some circumstances (e.g., multiple processes accessing a
+single socket), the condition that caused the
+.B SIGIO
+may have already disappeared when the process reacts to the signal.
+If this happens, the process should wait again because Linux
+will resend the signal later.
+.\" .SS Ancillary messages
+.SS /proc interfaces
+The core socket networking parameters can be accessed
+via files in the directory
+.IR /proc/sys/net/core/ .
+.TP
+.I rmem_default
+contains the default setting in bytes of the socket receive buffer.
+.TP
+.I rmem_max
+contains the maximum socket receive buffer size in bytes which a user may
+set by using the
+.B SO_RCVBUF
+socket option.
+.TP
+.I wmem_default
+contains the default setting in bytes of the socket send buffer.
+.TP
+.I wmem_max
+contains the maximum socket send buffer size in bytes which a user may
+set by using the
+.B SO_SNDBUF
+socket option.
+.TP
+.IR message_cost " and " message_burst
+configure the token bucket filter used to load limit warning messages
+caused by external network events.
+.TP
+.I netdev_max_backlog
+Maximum number of packets in the global input queue.
+.TP
+.I optmem_max
+Maximum length of ancillary data and user control data like the iovecs
+per socket.
+.\" netdev_fastroute is not documented because it is experimental
+.SS Ioctls
+These operations can be accessed using
+.BR ioctl (2):
+.P
+.in +4n
+.EX
+.IB error " = ioctl(" ip_socket ", " ioctl_type ", " &value_result ");"
+.EE
+.in
+.TP
+.B SIOCGSTAMP
+Return a
+.I struct timeval
+with the receive timestamp of the last packet passed to the user.
+This is useful for accurate round trip time measurements.
+See
+.BR setitimer (2)
+for a description of
+.IR "struct timeval" .
+.\"
+This ioctl should be used only if the socket options
+.B SO_TIMESTAMP
+and
+.B SO_TIMESTAMPNS
+are not set on the socket.
+Otherwise, it returns the timestamp of the
+last packet that was received while
+.B SO_TIMESTAMP
+and
+.B SO_TIMESTAMPNS
+were not set, or it fails if no such packet has been received,
+(i.e.,
+.BR ioctl (2)
+returns \-1 with
+.I errno
+set to
+.BR ENOENT ).
+.TP
+.B SIOCSPGRP
+Set the process or process group that is to receive
+.B SIGIO
+or
+.B SIGURG
+signals when I/O becomes possible or urgent data is available.
+The argument is a pointer to a
+.IR pid_t .
+For further details, see the description of
+.B F_SETOWN
+in
+.BR fcntl (2).
+.TP
+.B FIOASYNC
+Change the
+.B O_ASYNC
+flag to enable or disable asynchronous I/O mode of the socket.
+Asynchronous I/O mode means that the
+.B SIGIO
+signal or the signal set with
+.B F_SETSIG
+is raised when a new I/O event occurs.
+.IP
+Argument is an integer boolean flag.
+(This operation is synonymous with the use of
+.BR fcntl (2)
+to set the
+.B O_ASYNC
+flag.)
+.\"
+.TP
+.B SIOCGPGRP
+Get the current process or process group that receives
+.B SIGIO
+or
+.B SIGURG
+signals,
+or 0
+when none is set.
+.P
+Valid
+.BR fcntl (2)
+operations:
+.TP
+.B FIOGETOWN
+The same as the
+.B SIOCGPGRP
+.BR ioctl (2).
+.TP
+.B FIOSETOWN
+The same as the
+.B SIOCSPGRP
+.BR ioctl (2).
+.SH VERSIONS
+.B SO_BINDTODEVICE
+was introduced in Linux 2.0.30.
+.B SO_PASSCRED
+is new in Linux 2.2.
+The
+.I /proc
+interfaces were introduced in Linux 2.2.
+.B SO_RCVTIMEO
+and
+.B SO_SNDTIMEO
+are supported since Linux 2.3.41.
+Earlier, timeouts were fixed to
+a protocol-specific setting, and could not be read or written.
+.SH NOTES
+Linux assumes that half of the send/receive buffer is used for internal
+kernel structures; thus the values in the corresponding
+.I /proc
+files are twice what can be observed on the wire.
+.P
+Linux will allow port reuse only with the
+.B SO_REUSEADDR
+option
+when this option was set both in the previous program that performed a
+.BR bind (2)
+to the port and in the program that wants to reuse the port.
+This differs from some implementations (e.g., FreeBSD)
+where only the later program needs to set the
+.B SO_REUSEADDR
+option.
+Typically this difference is invisible, since, for example, a server
+program is designed to always set this option.
+.\" .SH AUTHORS
+.\" This man page was written by Andi Kleen.
+.SH SEE ALSO
+.BR wireshark (1),
+.BR bpf (2),
+.BR connect (2),
+.BR getsockopt (2),
+.BR setsockopt (2),
+.BR socket (2),
+.BR pcap (3),
+.BR address_families (7),
+.BR capabilities (7),
+.BR ddp (7),
+.BR ip (7),
+.BR ipv6 (7),
+.BR packet (7),
+.BR tcp (7),
+.BR udp (7),
+.BR unix (7),
+.BR tcpdump (8)
diff --git a/man/man7/spufs.7 b/man/man7/spufs.7
new file mode 100644
index 000000000..8f347d16f
--- /dev/null
+++ b/man/man7/spufs.7
@@ -0,0 +1,804 @@
+.\" Copyright (c) International Business Machines Corp., 2006
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" HISTORY:
+.\" 2005-09-28, created by Arnd Bergmann <arndb@de.ibm.com>,
+.\"   Mark Nutter <mnutter@us.ibm.com> and
+.\"   Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
+.\" 2006-06-16, revised by Eduardo M. Fleury <efleury@br.ibm.com>
+.\" 2007-07-10, quite a lot of polishing by mtk
+.\" 2007-09-28, updates for newer kernels by Jeremy Kerr <jk@ozlabs.org>
+.\"
+.TH spufs 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+spufs \- SPU filesystem
+.SH DESCRIPTION
+The SPU filesystem is used on PowerPC machines that implement the
+Cell Broadband Engine Architecture in order to access Synergistic
+Processor Units (SPUs).
+.P
+The filesystem provides a name space similar to POSIX shared
+memory or message queues.
+Users that have write permissions
+on the filesystem can use
+.BR spu_create (2)
+to establish SPU contexts under the
+.B spufs
+root directory.
+.P
+Every SPU context is represented by a directory containing
+a predefined set of files.
+These files can be
+used for manipulating the state of the logical SPU.
+Users can change permissions on the files, but can't
+add or remove files.
+.SS Mount options
+.TP
+.B uid=<uid>
+Set the user owning the mount point; the default is 0 (root).
+.TP
+.B gid=<gid>
+Set the group owning the mount point; the default is 0 (root).
+.TP
+.B mode=<mode>
+Set the mode of the top-level directory in
+.BR spufs ,
+as an octal mode string.
+The default is 0775.
+.SS Files
+The files in
+.B spufs
+mostly follow the standard behavior for regular system calls like
+.BR read (2)
+or
+.BR write (2),
+but often support only a subset of the operations
+supported on regular filesystems.
+This list details the supported
+operations and the deviations from the standard behavior described
+in the respective man pages.
+.P
+All files that support the
+.BR read (2)
+operation also support
+.BR readv (2)
+and all files that support the
+.BR write (2)
+operation also support
+.BR writev (2).
+All files support the
+.BR access (2)
+and
+.BR stat (2)
+family of operations, but for the latter call,
+the only fields of the returned
+.I stat
+structure that contain reliable information are
+.IR st_mode ,
+.IR st_nlink ,
+.IR st_uid ,
+and
+.IR st_gid .
+.P
+All files support the
+.BR chmod (2)/\c
+.BR fchmod (2)
+and
+.BR chown (2)/\c
+.BR fchown (2)
+operations, but will not be able to grant permissions that contradict
+the possible operations (e.g., read access on the
+.I wbox
+file).
+.P
+The current set of files is:
+.TP
+.I /capabilities
+Contains a comma-delimited string representing the capabilities of this
+SPU context.
+Possible capabilities are:
+.RS
+.TP
+.B sched
+This context may be scheduled.
+.TP
+.B step
+This context can be run in single-step mode, for debugging.
+.P
+New capabilities flags may be added in the future.
+.RE
+.TP
+.I /mem
+the contents of the local storage memory of the SPU.
+This can be accessed like a regular shared memory
+file and contains both code and data in the address
+space of the SPU.
+The possible operations on an open
+.I mem
+file are:
+.RS
+.TP
+.BR read (2)
+.TQ
+.BR pread (2)
+.TQ
+.BR write (2)
+.TQ
+.BR pwrite (2)
+.TQ
+.BR lseek (2)
+These operate as usual, with the exception that
+.BR lseek (2),
+.BR write (2),
+and
+.BR pwrite (2)
+are not supported beyond the end of the file.
+The file size
+is the size of the local storage of the SPU,
+which is normally 256 kilobytes.
+.TP
+.BR mmap (2)
+Mapping
+.I mem
+into the process address space provides access to the SPU local
+storage within the process address space.
+Only
+.B MAP_SHARED
+mappings are allowed.
+.RE
+.TP
+.I /regs
+Contains the saved general-purpose registers of the SPU context.
+This file contains the 128-bit values of each register,
+from register 0 to register 127, in order.
+This allows the general-purpose registers to be
+inspected for debugging.
+.IP
+Reading to or writing from this file requires that the context is
+scheduled out, so use of this file is not recommended in normal
+program operation.
+.IP
+The
+.I regs
+file is not present on contexts that have been created with the
+.B SPU_CREATE_NOSCHED
+flag.
+.TP
+.I /mbox
+The first SPU-to-CPU communication mailbox.
+This file is read-only and can be read in units of 4 bytes.
+The file can be used only in nonblocking mode \- even
+.BR poll (2)
+cannot be used to block on this file.
+The only possible operation on an open
+.I mbox
+file is:
+.RS
+.TP
+.BR read (2)
+If
+.I count
+is smaller than four,
+.BR read (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+If there is no data available in the mailbox (i.e., the SPU has not
+sent a mailbox message), the return value is set to \-1 and
+.I errno
+is set to
+.BR EAGAIN .
+When data
+has been read successfully, four bytes are placed in
+the data buffer and the value four is returned.
+.RE
+.TP
+.I /ibox
+The second SPU-to-CPU communication mailbox.
+This file is similar to the first mailbox file, but can be read
+in blocking I/O mode, thus calling
+.BR read (2)
+on an open
+.I ibox
+file will block until the SPU has written data to its interrupt mailbox
+channel (unless the file has been opened with
+.BR O_NONBLOCK ,
+see below).
+Also,
+.BR poll (2)
+and similar system calls can be used to monitor for the presence
+of mailbox data.
+.IP
+The possible operations on an open
+.I ibox
+file are:
+.RS
+.TP
+.BR read (2)
+If
+.I count
+is smaller than four,
+.BR read (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+If there is no data available in the mailbox and the file
+descriptor has been opened with
+.BR O_NONBLOCK ,
+the return value is set to \-1 and
+.I errno
+is set to
+.BR EAGAIN .
+.IP
+If there is no data available in the mailbox and the file
+descriptor has been opened without
+.BR O_NONBLOCK ,
+the call will
+block until the SPU writes to its interrupt mailbox channel.
+When data has been read successfully, four bytes are placed in
+the data buffer and the value four is returned.
+.TP
+.BR poll (2)
+Poll on the
+.I ibox
+file returns
+.I "(POLLIN | POLLRDNORM)"
+whenever data is available for reading.
+.RE
+.TP
+.I /wbox
+The CPU-to-SPU communication mailbox.
+It is write-only and can be written in units of four bytes.
+If the mailbox is full,
+.BR write (2)
+will block, and
+.BR poll (2)
+can be used to block until the mailbox is available for writing again.
+The possible operations on an open
+.I wbox
+file are:
+.RS
+.TP
+.BR write (2)
+If
+.I count
+is smaller than four,
+.BR write (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+If there is no space available in the mailbox and the file
+descriptor has been opened with
+.BR O_NONBLOCK ,
+the return
+value is set to \-1 and
+.I errno
+is set to
+.BR EAGAIN .
+.IP
+If there is no space available in the mailbox and the file
+descriptor has been opened without
+.BR O_NONBLOCK ,
+the call will block until the SPU reads from its
+PPE (PowerPC Processing Element)
+mailbox channel.
+When data has been written successfully,
+the system call returns four as its function result.
+.TP
+.BR poll (2)
+A poll on the
+.I wbox
+file returns
+.I "(POLLOUT | POLLWRNORM)"
+whenever space is available for writing.
+.RE
+.TP
+.I /mbox_stat
+.TQ
+.I /ibox_stat
+.TQ
+.I /wbox_stat
+These are read-only files that contain the length of the current
+queue of each mailbox\[em]that is, how many words can be read from
+.IR mbox " or " ibox
+or how many words can be written to
+.I wbox
+without blocking.
+The files can be read only in four-byte units and return
+a big-endian binary integer number.
+The only possible operation on an open
+.I *box_stat
+file is:
+.RS
+.TP
+.BR read (2)
+If
+.I count
+is smaller than four,
+.BR read (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+Otherwise, a four-byte value is placed in the data buffer.
+This value is the number of elements that can be read from (for
+.I mbox_stat
+and
+.IR ibox_stat )
+or written to (for
+.IR wbox_stat )
+the respective mailbox without blocking or returning an
+.B EAGAIN
+error.
+.RE
+.TP
+.I /npc
+.TQ
+.I /decr
+.TQ
+.I /decr_status
+.TQ
+.I /spu_tag_mask
+.TQ
+.I /event_mask
+.TQ
+.I /event_status
+.TQ
+.I /srr0
+.TQ
+.I /lslr
+Internal registers of the SPU.
+These files contain an ASCII string
+representing the hex value of the specified register.
+Reads and writes on these
+files (except for
+.IR npc ,
+see below) require that the SPU context be scheduled out,
+so frequent access to
+these files is not recommended for normal program operation.
+.IP
+The contents of these files are:
+.RS
+.TP 16
+.I npc
+Next Program Counter \- valid only when the SPU is in a stopped state.
+.TP
+.I decr
+SPU Decrementer
+.TP
+.I decr_status
+Decrementer Status
+.TP
+.I spu_tag_mask
+MFC tag mask for SPU DMA
+.TP
+.I event_mask
+Event mask for SPU interrupts
+.TP
+.I event_status
+Number of SPU events pending (read-only)
+.TP
+.I srr0
+Interrupt Return address register
+.TP
+.I lslr
+Local Store Limit Register
+.RE
+.IP
+The possible operations on these files are:
+.RS
+.TP
+.BR read (2)
+Reads the current register value.
+If the register value is larger than the buffer passed to the
+.BR read (2)
+system call, subsequent reads will continue reading from the same
+buffer, until the end of the buffer is reached.
+.IP
+When a complete string has been read, all subsequent read operations
+will return zero bytes and a new file descriptor needs to be opened
+to read a new value.
+.TP
+.BR write (2)
+A
+.BR write (2)
+operation on the file sets the register to the
+value given in the string.
+The string is parsed from the beginning
+until the first nonnumeric character or the end of the buffer.
+Subsequent writes to the same file descriptor overwrite the
+previous setting.
+.IP
+Except for the
+.I npc
+file, these files are not present on contexts that have been created with
+the
+.B SPU_CREATE_NOSCHED
+flag.
+.RE
+.TP
+.I /fpcr
+This file provides access to the Floating Point Status and
+Control Register (fcpr) as a binary, four-byte file.
+The operations on the
+.I fpcr
+file are:
+.RS
+.TP
+.BR read (2)
+If
+.I count
+is smaller than four,
+.BR read (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+Otherwise, a four-byte value is placed in the data buffer;
+this is the current value of the
+.I fpcr
+register.
+.TP
+.BR write (2)
+If
+.I count
+is smaller than four,
+.BR write (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+Otherwise, a four-byte value is copied from the data buffer,
+updating the value of the
+.I fpcr
+register.
+.RE
+.TP
+.I /signal1
+.TQ
+.I /signal2
+The files provide access to the two signal notification channels
+of an SPU.
+These are read-write files that operate on four-byte words.
+Writing to one of these files triggers an interrupt on the SPU.
+The value written to the signal files can
+be read from the SPU through a channel read or from
+host user space through the file.
+After the value has been read by the SPU, it is reset to zero.
+The possible operations on an open
+.I signal1
+or
+.I signal2
+file are:
+.RS
+.TP
+.BR read (2)
+If
+.I count
+is smaller than four,
+.BR read (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+Otherwise, a four-byte value is placed in the data buffer;
+this is the current value of the specified signal notification
+register.
+.TP
+.BR write (2)
+If
+.I count
+is smaller than four,
+.BR write (2)
+returns \-1 and sets
+.I errno
+to
+.BR EINVAL .
+Otherwise, a four-byte value is copied from the data buffer,
+updating the value of the specified signal notification
+register.
+The signal notification register will either be replaced with
+the input data or will be updated to the bitwise OR operation
+of the old value and the input data, depending on the contents
+of the
+.I signal1_type
+or
+.I signal2_type
+files respectively.
+.RE
+.TP
+.I /signal1_type
+.TQ
+.I /signal2_type
+These two files change the behavior of the
+.I signal1
+and
+.I signal2
+notification files.
+They contain a numeric ASCII string which is read
+as either "1" or "0".
+In mode 0 (overwrite), the hardware replaces the contents
+of the signal channel with the data that is written to it.
+In mode 1 (logical OR), the hardware accumulates the bits
+that are subsequently written to it.
+The possible operations on an open
+.I signal1_type
+or
+.I signal2_type
+file are:
+.RS
+.TP
+.BR read (2)
+When the count supplied to the
+.BR read (2)
+call is shorter than the required length for the digit (plus a newline
+character), subsequent reads from the same file descriptor will
+complete the string.
+When a complete string has been read, all subsequent read operations
+will return zero bytes and a new file descriptor needs to be opened
+to read the value again.
+.TP
+.BR write (2)
+A
+.BR write (2)
+operation on the file sets the register to the
+value given in the string.
+The string is parsed from the beginning
+until the first nonnumeric character or the end of the buffer.
+Subsequent writes to the same file descriptor overwrite the
+previous setting.
+.RE
+.TP
+.I /mbox_info
+.TQ
+.I /ibox_info
+.TQ
+.I /wbox_info
+.TQ
+.I /dma_into
+.TQ
+.I /proxydma_info
+Read-only files that contain the saved state of the SPU mailboxes and
+DMA queues.
+This allows the SPU status to be inspected, mainly for debugging.
+The
+.I mbox_info
+and
+.I ibox_info
+files each contain the four-byte mailbox message that has been written
+by the SPU.
+If no message has been written to these mailboxes, then
+contents of these files is undefined.
+The
+.IR mbox_stat ,
+.IR ibox_stat ,
+and
+.I wbox_stat
+files contain the available message count.
+.IP
+The
+.I wbox_info
+file contains an array of four-byte mailbox messages, which have been
+sent to the SPU.
+With current CBEA machines, the array is four items in
+length, so up to 4 * 4 = 16 bytes can be read from this file.
+If any mailbox queue entry is empty,
+then the bytes read at the corresponding location are undefined.
+.IP
+The
+.I dma_info
+file contains the contents of the SPU MFC DMA queue, represented as the
+following structure:
+.IP
+.in +4n
+.EX
+struct spu_dma_info {
+    uint64_t         dma_info_type;
+    uint64_t         dma_info_mask;
+    uint64_t         dma_info_status;
+    uint64_t         dma_info_stall_and_notify;
+    uint64_t         dma_info_atomic_command_status;
+    struct mfc_cq_sr dma_info_command_data[16];
+};
+.EE
+.in
+.IP
+The last member of this data structure is the actual DMA queue,
+containing 16 entries.
+The
+.I mfc_cq_sr
+structure is defined as:
+.IP
+.in +4n
+.EX
+struct mfc_cq_sr {
+    uint64_t mfc_cq_data0_RW;
+    uint64_t mfc_cq_data1_RW;
+    uint64_t mfc_cq_data2_RW;
+    uint64_t mfc_cq_data3_RW;
+};
+.EE
+.in
+.IP
+The
+.I proxydma_info
+file contains similar information, but describes the proxy DMA queue
+(i.e., DMAs initiated by entities outside the SPU) instead.
+The file is in the following format:
+.IP
+.in +4n
+.EX
+struct spu_proxydma_info {
+    uint64_t         proxydma_info_type;
+    uint64_t         proxydma_info_mask;
+    uint64_t         proxydma_info_status;
+    struct mfc_cq_sr proxydma_info_command_data[8];
+};
+.EE
+.in
+.IP
+Accessing these files requires that the SPU context is scheduled out -
+frequent use can be inefficient.
+These files should not be used for normal program operation.
+.IP
+These files are not present on contexts that have been created with the
+.B SPU_CREATE_NOSCHED
+flag.
+.TP
+.I /cntl
+This file provides access to the SPU Run Control and SPU status
+registers, as an ASCII string.
+The following operations are supported:
+.RS
+.TP
+.BR read (2)
+Reads from the
+.I cntl
+file will return an ASCII string with the hex
+value of the SPU Status register.
+.TP
+.BR write (2)
+Writes to the
+.I cntl
+file will set the context's SPU Run Control register.
+.RE
+.TP
+.I /mfc
+Provides access to the Memory Flow Controller of the SPU.
+Reading from the file returns the contents of the
+SPU's MFC Tag Status register, and
+writing to the file initiates a DMA from the MFC.
+The following operations are supported:
+.RS
+.TP
+.BR write (2)
+Writes to this file need to be in the format of a MFC DMA command,
+defined as follows:
+.IP
+.in +4n
+.EX
+struct mfc_dma_command {
+    int32_t  pad;    /* reserved */
+    uint32_t lsa;    /* local storage address */
+    uint64_t ea;     /* effective address */
+    uint16_t size;   /* transfer size */
+    uint16_t tag;    /* command tag */
+    uint16_t class;  /* class ID */
+    uint16_t cmd;    /* command opcode */
+};
+.EE
+.in
+.IP
+Writes are required to be exactly
+.I sizeof(struct mfc_dma_command)
+bytes in size.
+The command will be sent to the SPU's MFC proxy queue, and the
+tag stored in the kernel (see below).
+.TP
+.BR read (2)
+Reads the contents of the tag status register.
+If the file is opened in blocking mode (i.e., without
+.BR O_NONBLOCK ),
+then the read will block until a
+DMA tag (as performed by a previous write) is complete.
+In nonblocking mode,
+the MFC tag status register will be returned without waiting.
+.TP
+.BR poll (2)
+Calling
+.BR poll (2)
+on the
+.I mfc
+file will block until a new DMA can be
+started (by checking for
+.BR POLLOUT )
+or until a previously started DMA
+(by checking for
+.BR POLLIN )
+has been completed.
+.IP
+.I /mss
+Provides access to the MFC MultiSource Synchronization (MSS) facility.
+By
+.BR mmap (2)-ing
+this file, processes can access the MSS area of the SPU.
+.IP
+The following operations are supported:
+.TP
+.BR mmap (2)
+Mapping
+.B mss
+into the process address space gives access to the SPU MSS area
+within the process address space.
+Only
+.B MAP_SHARED
+mappings are allowed.
+.RE
+.TP
+.I /psmap
+Provides access to the whole problem-state mapping of the SPU.
+Applications can use this area to interface to the SPU, rather than
+writing to individual register files in
+.BR spufs .
+.IP
+The following operations are supported:
+.RS
+.TP
+.BR mmap (2)
+Mapping
+.B psmap
+gives a process a direct map of the SPU problem state area.
+Only
+.B MAP_SHARED
+mappings are supported.
+.RE
+.TP
+.I /phys\-id
+Read-only file containing the physical SPU number that the SPU context
+is running on.
+When the context is not running, this file contains the
+string "\-1".
+.IP
+The physical SPU number is given by an ASCII hex string.
+.TP
+.I /object\-id
+Allows applications to store (or retrieve) a single 64-bit ID into the
+context.
+This ID is later used by profiling tools to uniquely identify
+the context.
+.RS
+.TP
+.BR write (2)
+By writing an ASCII hex value into this file, applications can set the
+object ID of the SPU context.
+Any previous value of the object ID is overwritten.
+.TP
+.BR read (2)
+Reading this file gives an ASCII hex string representing the object ID
+for this SPU context.
+.RE
+.SH EXAMPLES
+To automatically
+.BR mount (8)
+the SPU filesystem when booting, at the location
+.I /spu
+chosen by the user, put this line into the
+.BR fstab (5)
+configuration file:
+.EX
+none /spu spufs gid=spu 0 0
+.EE
+.\" .SH AUTHORS
+.\" Arnd Bergmann <arndb@de.ibm.com>, Mark Nutter <mnutter@us.ibm.com>,
+.\" Ulrich Weigand <Ulrich.Weigand@de.ibm.com>, Jeremy Kerr <jk@ozlabs.org>
+.SH SEE ALSO
+.BR close (2),
+.BR spu_create (2),
+.BR spu_run (2),
+.BR capabilities (7)
+.P
+.I The Cell Broadband Engine Architecture (CBEA) specification
diff --git a/man/man7/standards.7 b/man/man7/standards.7
new file mode 100644
index 000000000..06a9f0cec
--- /dev/null
+++ b/man/man7/standards.7
@@ -0,0 +1,307 @@
+.\" Copyright (c) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH standards 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+standards \- C and UNIX Standards
+.SH DESCRIPTION
+The STANDARDS section that appears in many manual pages identifies
+various standards to which the documented interface conforms.
+The following list briefly describes these standards.
+.TP
+.B V7
+Version 7 (also known as Seventh Edition) UNIX,
+released by AT&T/Bell Labs in 1979.
+After this point, UNIX systems diverged into two main dialects:
+BSD and System V.
+.TP
+.B 4.2BSD
+This is an implementation standard defined by the 4.2 release
+of the
+.IR "Berkeley Software Distribution",
+released by the University of California at Berkeley.
+This was the first Berkeley release that contained a TCP/IP
+stack and the sockets API.
+4.2BSD was released in 1983.
+.IP
+Earlier major BSD releases included
+.I 3BSD
+(1980),
+.I 4BSD
+(1980),
+and
+.I 4.1BSD
+(1981).
+.TP
+.B 4.3BSD
+The successor to 4.2BSD, released in 1986.
+.TP
+.B 4.4BSD
+The successor to 4.3BSD, released in 1993.
+This was the last major Berkeley release.
+.TP
+.B System V
+This is an implementation standard defined by AT&T's milestone 1983
+release of its commercial System V (five) release.
+The previous major AT&T release was
+.IR "System III" ,
+released in 1981.
+.TP
+.B System V release 2 (SVr2)
+This was the next System V release, made in 1985.
+The SVr2 was formally described in the
+.I "System V Interface Definition version 1"
+.RI ( "SVID 1" )
+published in 1985.
+.TP
+.B System V release 3 (SVr3)
+This was the successor to SVr2, released in 1986.
+This release was formally described in the
+.I "System V Interface Definition version 2"
+.RI ( "SVID 2" ).
+.TP
+.B System V release 4 (SVr4)
+This was the successor to SVr3, released in 1989.
+This version of System V is described in the "Programmer's Reference
+Manual: Operating System API (Intel processors)" (Prentice-Hall
+1992, ISBN 0-13-951294-2)
+This release was formally described in the
+.I "System V Interface Definition version 3"
+.RI ( "SVID 3" ),
+and is considered the definitive System V release.
+.TP
+.B SVID 4
+System V Interface Definition version 4, issued in 1995.
+Available online at
+.UR http://www.sco.com\:/developers\:/devspecs/
+.UE .
+.TP
+.B C89
+This was the first C language standard, ratified by ANSI
+(American National Standards Institute) in 1989
+.RI ( X3.159-1989 ).
+Sometimes this is known as
+.IR "ANSI C" ,
+but since C99 is also an
+ANSI standard, this term is ambiguous.
+This standard was also ratified by
+ISO (International Standards Organization) in 1990
+.RI ( "ISO/IEC 9899:1990" ),
+and is thus occasionally referred to as
+.IR "ISO C90" .
+.TP
+.B C99
+This revision of the C language standard was ratified by ISO in 1999
+.RI ( "ISO/IEC 9899:1999" ).
+Available online at
+.UR http://www.open\-std.org\:/jtc1\:/sc22\:/wg14\:/www\:/standards
+.UE .
+.TP
+.B C11
+This revision of the C language standard was ratified by ISO in 2011
+.RI ( "ISO/IEC 9899:2011" ).
+.TP
+.B LFS
+The Large File Summit specification, completed in 1996.
+This specification defined mechanisms that allowed 32-bit systems
+to support the use of large files (i.e., 64-bit file offsets).
+See
+.UR https://www.opengroup.org\:/platform\:/lfs.html
+.UE .
+.TP
+.B POSIX.1-1988
+This was the first POSIX standard,
+ratified by IEEE as IEEE Std 1003.1-1988,
+and subsequently adopted (with minor revisions) as an ISO standard in 1990.
+The term "POSIX" was coined by Richard Stallman.
+.TP
+.B POSIX.1-1990
+"Portable Operating System Interface for Computing Environments".
+IEEE 1003.1-1990 part 1, ratified by ISO in 1990
+.RI ( "ISO/IEC 9945-1:1990" ).
+.TP
+.B POSIX.2
+IEEE Std 1003.2-1992,
+describing commands and utilities, ratified by ISO in 1993
+.RI ( "ISO/IEC 9945-2:1993" ).
+.TP
+.BR POSIX.1b " (formerly known as \fIPOSIX.4\fP)"
+IEEE Std 1003.1b-1993,
+describing real-time facilities
+for portable operating systems, ratified by ISO in 1996
+.RI ( "ISO/IEC 9945-1:1996" ).
+.TP
+.BR POSIX.1c " (formerly known as \fIPOSIX.4a\fP)"
+IEEE Std 1003.1c-1995, which describes the POSIX threads interfaces.
+.TP
+.B POSIX.1d
+IEEE Std 1003.1d-1999, which describes additional real-time extensions.
+.TP
+.B POSIX.1g
+IEEE Std 1003.1g-2000, which describes networking APIs (including sockets).
+.TP
+.B POSIX.1j
+IEEE Std 1003.1j-2000, which describes advanced real-time extensions.
+.TP
+.B POSIX.1-1996
+A 1996 revision of POSIX.1 which incorporated POSIX.1b and POSIX.1c.
+.TP
+.B XPG3
+Released in 1989, this was the first release of the X/Open
+Portability Guide to be based on a POSIX standard (POSIX.1-1988).
+This multivolume guide was developed by the X/Open Group,
+a multivendor consortium.
+.TP
+.B XPG4
+A revision of the X/Open Portability Guide, released in 1992.
+This revision incorporated POSIX.2.
+.TP
+.B XPG4v2
+A 1994 revision of XPG4.
+This is also referred to as
+.IR "Spec 1170" ,
+where 1170 referred to the number of interfaces
+defined by this standard.
+.TP
+.B "SUS (SUSv1)"
+Single UNIX Specification.
+This was a repackaging of XPG4v2 and other X/Open standards
+(X/Open Curses Issue 4 version 2,
+X/Open Networking Service (XNS) Issue 4).
+Systems conforming to this standard can be branded
+.IR "UNIX 95" .
+.TP
+.B SUSv2
+Single UNIX Specification version 2.
+Sometimes also referred to (incorrectly) as
+.IR XPG5 .
+This standard appeared in 1997.
+Systems conforming to this standard can be branded
+.IR "UNIX 98" .
+See also
+.UR http://www.unix.org\:/version2/
+.UE .)
+.TP
+.B POSIX.1-2001
+.TQ
+.B SUSv3
+This was a 2001 revision and consolidation of the
+POSIX.1, POSIX.2, and SUS standards into a single document,
+conducted under the auspices of the Austin Group
+.UR http://www.opengroup.org\:/austin/
+.UE .
+The standard is available online at
+.UR http://www.unix.org\:/version3/
+.UE .
+.IP
+The standard defines two levels of conformance:
+.IR "POSIX conformance" ,
+which is a baseline set of interfaces required of a conforming system;
+and
+.IR "XSI Conformance",
+which additionally mandates a set of interfaces
+(the "XSI extension") which are only optional for POSIX conformance.
+XSI-conformant systems can be branded
+.IR "UNIX 03" .
+.IP
+The POSIX.1-2001 document is broken into four parts:
+.IP
+.BR XBD :
+Definitions, terms, and concepts, header file specifications.
+.IP
+.BR XSH :
+Specifications of functions (i.e., system calls and library
+functions in actual implementations).
+.IP
+.BR XCU :
+Specifications of commands and utilities
+(i.e., the area formerly described by POSIX.2).
+.IP
+.BR XRAT :
+Informative text on the other parts of the standard.
+.IP
+POSIX.1-2001 is aligned with C99, so that all of the
+library functions standardized in C99 are also
+standardized in POSIX.1-2001.
+.IP
+The Single UNIX Specification version 3 (SUSv3) comprises the
+Base Specifications containing XBD, XSH, XCU, and XRAT as above,
+plus X/Open Curses Issue 4 version 2 as an extra volume that is
+not in POSIX.1-2001.
+.IP
+Two Technical Corrigenda (minor fixes and improvements)
+of the original 2001 standard have occurred:
+TC1 in 2003
+and TC2 in 2004.
+.TP
+.B POSIX.1-2008
+.TQ
+.B SUSv4
+Work on the next revision of POSIX.1/SUS was completed and
+ratified in 2008.
+The standard is available online at
+.UR http://www.unix.org\:/version4/
+.UE .
+.IP
+The changes in this revision are not as large as those
+that occurred for POSIX.1-2001/SUSv3,
+but a number of new interfaces are added
+and various details of existing specifications are modified.
+Many of the interfaces that were optional in
+POSIX.1-2001 become mandatory in the 2008 revision of the standard.
+A few interfaces that are present in POSIX.1-2001 are marked
+as obsolete in POSIX.1-2008, or removed from the standard altogether.
+.IP
+The revised standard is structured in the same way as its predecessor.
+The Single UNIX Specification version 4 (SUSv4) comprises the
+Base Specifications containing XBD, XSH, XCU, and XRAT,
+plus X/Open Curses Issue 7 as an extra volume that is
+not in POSIX.1-2008.
+.IP
+Again there are two levels of conformance: the baseline
+.IR "POSIX Conformance" ,
+and
+.IR "XSI Conformance" ,
+which mandates an additional set of interfaces
+beyond those in the base specification.
+.IP
+In general, where the STANDARDS section of a manual page
+lists POSIX.1-2001, it can be assumed that the interface also
+conforms to POSIX.1-2008, unless otherwise noted.
+.IP
+Technical Corrigendum 1 (minor fixes and improvements)
+of this standard was released in 2013.
+.IP
+Technical Corrigendum 2 of this standard was released in 2016.
+.IP
+Further information can be found on the Austin Group web site,
+.UR http://www.opengroup.org\:/austin/
+.UE .
+.TP
+.B SUSv4 2016 edition
+This is equivalent to POSIX.1-2008, with the addition of
+Technical Corrigenda 1 and 2 and the XCurses specification.
+.TP
+.B POSIX.1-2017
+This revision of POSIX is technically identical to POSIX.1-2008 with
+Technical Corrigenda 1 and 2 applied.
+.TP
+.B SUSv4 2018 edition
+This is equivalent to POSIX.1-2017, with the addition of
+the XCurses specification.
+.P
+The interfaces documented in POSIX.1/SUS are available as
+manual pages under sections 0p (header files), 1p (commands),
+and 3p (functions);
+thus one can write "man 3p open".
+.SH SEE ALSO
+.BR getconf (1),
+.BR confstr (3),
+.BR pathconf (3),
+.BR sysconf (3),
+.BR attributes (7),
+.BR feature_test_macros (7),
+.BR libc (7),
+.BR posixoptions (7),
+.BR system_data_types (7)
diff --git a/man/man7/string_copying.7 b/man/man7/string_copying.7
new file mode 100644
index 000000000..281fff8be
--- /dev/null
+++ b/man/man7/string_copying.7
@@ -0,0 +1,767 @@
+.\" Copyright 2022 Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.TH string_copying 7 (date) "Linux man-pages (unreleased)"
+.\" ----- NAME :: -----------------------------------------------------/
+.SH NAME
+stpcpy,
+strcpy, strcat,
+stpecpy,
+strtcpy,
+strlcpy, strlcat,
+stpncpy,
+strncpy,
+strncat
+\- copying strings and character sequences
+.\" ----- SYNOPSIS :: -------------------------------------------------/
+.SH SYNOPSIS
+.\" ----- SYNOPSIS :: (Null-terminated) strings -----------------------/
+.SS Strings
+.nf
+// Chain-copy a string.
+.BI "char *stpcpy(char *restrict " dst ", const char *restrict " src );
+.P
+// Copy/catenate a string.
+.BI "char *strcpy(char *restrict " dst ", const char *restrict " src );
+.BI "char *strcat(char *restrict " dst ", const char *restrict " src );
+.P
+// Chain-copy a string with truncation.
+.BI "char *stpecpy(char *" dst ", char " end "[0], const char *restrict " src );
+.P
+// Copy/catenate a string with truncation.
+.BI "ssize_t strtcpy(char " dst "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "               size_t " dsize );
+.BI "size_t strlcpy(char " dst "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "               size_t " dsize );
+.BI "size_t strlcat(char " dst "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "               size_t " dsize );
+.fi
+.\" ----- SYNOPSIS :: Null-padded character sequences --------/
+.SS Null-padded character sequences
+.nf
+// Fill a fixed-size buffer with characters from a string
+// and pad with null bytes.
+.BI "char *strncpy(char " dst "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "               size_t " dsize );
+.BI "char *stpncpy(char " dst "[restrict ." dsize "], \
+const char *restrict " src ,
+.BI "               size_t " dsize );
+.P
+// Chain-copy a null-padded character sequence into a character sequence.
+.I mempcpy(dst, src, strnlen(src, NITEMS(src)));
+.P
+// Chain-copy a null-padded character sequence into a string.
+.I stpcpy(mempcpy(dst, src, strnlen(src, NITEMS(src))), \[dq]\[dq]);
+.P
+// Catenate a null-padded character sequence into a string.
+.BI "char *strncat(char *restrict " dst ", const char " src "[restrict ." ssize ],
+.BI "               size_t " ssize );
+.fi
+.\" ----- SYNOPSIS :: Known-length character sequences --------------------/
+.SS Known-length character sequences
+.nf
+// Chain-copy a known-length character sequence.
+.BI "void *mempcpy(void " dst "[restrict ." len "], \
+const void " src "[restrict ." len ],
+.BI "               size_t " len );
+.P
+// Chain-copy a known-length character sequence into a string.
+.I stpcpy(mempcpy(dst, src, len), \[dq]\[dq]);
+.fi
+.SH DESCRIPTION
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: -----------------/
+.SS Terms (and abbreviations)
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: string (str) ----/
+.TP
+.IR "string " ( str )
+is a sequence of zero or more non-null characters followed by a null character.
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: null-padded character seq
+.TP
+.I character sequence
+is a sequence of zero or more non-null characters.
+A program should never use a character sequence where a string is required.
+However, with appropriate care,
+a string can be used in the place of a character sequence.
+.RS
+.TP
+.I null-padded character sequence
+Character sequences can be contained in fixed-size buffers,
+which contain padding null bytes after the character sequence,
+to fill the rest of the buffer
+without affecting the character sequence;
+however, those padding null bytes are not part of the character sequence.
+Don't confuse null-padded with null-terminated:
+null-padded means 0 or more padding null bytes,
+while null-terminated means exactly 1 terminating null character.
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: known-length character sequence
+.TP
+.I known-length character sequence
+Character sequence delimited by its length.
+It may be a slice of a larger character sequence,
+or even of a string.
+.RE
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: length (len) ----/
+.TP
+.IR "length " ( len )
+is the number of non-null characters in a string or character sequence.
+It is the return value of
+.I strlen(str)
+and of
+.IR "strnlen(buf, size)" .
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: size ------------/
+.TP
+.I size
+refers to the entire buffer
+where the string or character sequence is contained.
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: end -------------/
+.TP
+.I end
+is the name of a pointer to one past the last element of a buffer.
+It is equivalent to
+.IR &str[size] .
+It is used as a sentinel value,
+to be able to truncate strings or character sequences
+instead of overrunning the containing buffer.
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: copy ------------/
+.TP
+.I copy
+This term is used when
+the writing starts at the first element pointed to by
+.IR dst .
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: catenate --------/
+.TP
+.I catenate
+This term is used when
+a function first finds the terminating null character in
+.IR dst ,
+and then starts writing at that position.
+.\" ----- DESCRIPTION :: Terms (and abbreviations) :: chain -----------/
+.TP
+.I chain
+This term is used when
+it's the programmer who provides
+a pointer to the terminating null character in the string
+.I dst
+(or one after the last character in a character sequence),
+and the function starts writing at that location.
+The function returns
+a pointer to the new location of the terminating null character
+(or one after the last character in a character sequence)
+after the call,
+so that the programmer can use it to chain such calls.
+.\" ----- DESCRIPTION :: Copy, catenate, and chain-copy ---------------/
+.SS Copy, catenate, and chain-copy
+Originally,
+there was a distinction between functions that copy and those that catenate.
+However, newer functions that copy while allowing chaining
+cover both use cases with a single API.
+They are also algorithmically faster,
+since they don't need to search for
+the terminating null character of the existing string.
+However, functions that catenate have a much simpler use,
+so if performance is not important,
+it can make sense to use them for improving readability.
+.P
+The pointer returned by functions that allow chaining
+is a byproduct of the copy operation,
+so it has no performance costs.
+Functions that return such a pointer,
+and thus can be chained,
+have names of the form
+.RB * stp *(),
+since it's common to name the pointer just
+.IR p .
+.P
+Chain-copying functions that truncate
+should accept a pointer to the end of the destination buffer,
+and have names of the form
+.RB * stpe *().
+This allows not having to recalculate the remaining size after each call.
+.\" ----- DESCRIPTION :: Truncate or not? -----------------------------/
+.SS Truncate or not?
+The first thing to note is that programmers should be careful with buffers,
+so they always have the correct size,
+and truncation is not necessary.
+.P
+In most cases,
+truncation is not desired,
+and it is simpler to just do the copy.
+Simpler code is safer code.
+Programming against programming mistakes by adding more code
+just adds more points where mistakes can be made.
+.P
+Nowadays,
+compilers can detect most programmer errors with features like
+compiler warnings,
+static analyzers, and
+.B \%_FORTIFY_SOURCE
+(see
+.BR ftm (7)).
+Keeping the code simple
+helps these overflow-detection features be more precise.
+.P
+When validating user input,
+code should normally not truncate,
+but instead fail and prevent the copy at all.
+.P
+In some cases,
+however,
+it makes sense to truncate.
+.P
+Functions that truncate:
+.IP \[bu] 3
+.BR stpecpy ()
+.IP \[bu]
+.BR strtcpy ()
+.IP \[bu]
+.BR strlcpy (3bsd)
+and
+.BR strlcat (3bsd)
+are similar, but have important performance problems; see BUGS.
+.IP \[bu]
+.BR stpncpy (3)
+and
+.BR strncpy (3)
+also truncate, but they don't write strings,
+but rather null-padded character sequences.
+.\" ----- DESCRIPTION :: Null-padded character sequences --------------/
+.SS Null-padded character sequences
+For historic reasons,
+some standard APIs and file formats,
+such as
+.BR utmpx (5)
+and
+.BR tar (1),
+use null-padded character sequences in fixed-size buffers.
+To interface with them,
+specialized functions need to be used.
+.P
+To copy bytes from strings into these buffers, use
+.BR strncpy (3)
+or
+.BR stpncpy (3).
+.P
+To read a null-padded character sequence,
+use
+.IR "strnlen(src,\ NITEMS(src))" ,
+and then you can treat it as a known-length character sequence;
+or use
+.BR strncat (3)
+directly.
+.\" ----- DESCRIPTION :: Known-length character sequences -----------------/
+.SS Known-length character sequences
+The simplest character sequence copying function is
+.BR mempcpy (3).
+It requires always knowing the length of your character sequences,
+for which structures can be used.
+It makes the code much faster,
+since you always know the length of your character sequences,
+and can do the minimal copies and length measurements.
+.BR mempcpy (3)
+copies character sequences,
+so you need to explicitly set the terminating null character
+if you need a string.
+.P
+In programs that make considerable use of strings or character sequences,
+and need the best performance,
+using overlapping character sequences can make a big difference.
+It allows holding subsequences of a larger character sequence,
+while not duplicating memory
+nor using time to do a copy.
+.P
+However, this is delicate,
+since it requires using character sequences.
+C library APIs use strings,
+so programs that use character sequences
+will have to take care of differentiating strings from character sequences.
+.P
+To copy a known-length character sequence, use
+.BR mempcpy (3).
+.P
+To copy a known-length character sequence into a string, use
+.IR "\%stpcpy(mempcpy(dst,\ src,\ len),\ \[dq]\[dq])" .
+.P
+A string is also accepted as input,
+because
+.BR mempcpy (3)
+asks for the length,
+and a string is composed of a character sequence of the same length
+plus a terminating null character.
+.\" ----- DESCRIPTION :: String vs character sequence -----------------/
+.SS String vs character sequence
+Some functions only operate on strings.
+Those require that the input
+.I src
+is a string,
+and guarantee an output string
+(even when truncation occurs).
+Functions that catenate
+also require that
+.I dst
+holds a string before the call.
+List of functions:
+.IP \[bu] 3
+.PD 0
+.BR stpcpy (3)
+.IP \[bu]
+.BR strcpy (3),
+.BR strcat (3)
+.IP \[bu]
+.BR stpecpy ()
+.IP \[bu]
+.BR strtcpy ()
+.IP \[bu]
+.BR strlcpy (3bsd),
+.BR strlcat (3bsd)
+.PD
+.P
+Other functions require an input string,
+but create a character sequence as output.
+These functions have confusing names,
+and have a long history of misuse.
+List of functions:
+.IP \[bu] 3
+.PD 0
+.BR stpncpy (3)
+.IP \[bu]
+.BR strncpy (3)
+.PD
+.P
+Other functions operate on an input character sequence,
+and create an output string.
+Functions that catenate
+also require that
+.I dst
+holds a string before the call.
+.BR strncat (3)
+has an even more misleading name than the functions above.
+List of functions:
+.IP \[bu] 3
+.BR strncat (3)
+.P
+Other functions operate on an input character sequence
+to create an output character sequence.
+List of functions:
+.IP \[bu] 3
+.BR mempcpy (3)
+.\" ----- DESCRIPTION :: Functions :: ---------------------------------/
+.SS Functions
+.\" ----- DESCRIPTION :: Functions :: stpcpy(3) -----------------------/
+.TP
+.BR stpcpy (3)
+Copy the input string into a destination string.
+The programmer is responsible for allocating a buffer large enough.
+It returns a pointer suitable for chaining.
+.\" ----- DESCRIPTION :: Functions :: strcpy(3), strcat(3) ------------/
+.TP
+.BR strcpy (3)
+.TQ
+.BR strcat (3)
+Copy and catenate the input string into a destination string.
+The programmer is responsible for allocating a buffer large enough.
+The return value is useless.
+.IP
+.BR stpcpy (3)
+is a faster alternative to these functions.
+.\" ----- DESCRIPTION :: Functions :: stpecpy() -----------------------/
+.TP
+.BR stpecpy ()
+Chain-copy the input string into a destination string.
+If the destination buffer,
+limited by a pointer to its end,
+isn't large enough to hold the copy,
+the resulting string is truncated
+(but it is guaranteed to be null-terminated).
+It returns a pointer suitable for chaining.
+Truncation needs to be detected only once after the last chained call.
+.IP
+This function is not provided by any library;
+see EXAMPLES for a reference implementation.
+.\" ----- DESCRIPTION :: Functions :: strtcpy() -----------------------/
+.TP
+.BR strtcpy ()
+Copy the input string into a destination string.
+If the destination buffer isn't large enough to hold the copy,
+the resulting string is truncated
+(but it is guaranteed to be null-terminated).
+It returns the length of the string,
+or \-1 if it truncated.
+.IP
+This function is not provided by any library;
+see EXAMPLES for a reference implementation.
+.\" ----- DESCRIPTION :: Functions :: strlcpy(3bsd), strlcat(3bsd) ----/
+.TP
+.BR strlcpy (3bsd)
+.TQ
+.BR strlcat (3bsd)
+Copy and catenate the input string into a destination string.
+If the destination buffer,
+limited by its size,
+isn't large enough to hold the copy,
+the resulting string is truncated
+(but it is guaranteed to be null-terminated).
+They return the length of the total string they tried to create.
+.IP
+Check BUGS before using these functions.
+.IP
+.BR strtcpy ()
+and
+.BR stpecpy ()
+are better alternatives to these functions.
+.\" ----- DESCRIPTION :: Functions :: stpncpy(3) ----------------------/
+.TP
+.BR stpncpy (3)
+Copy the input string into
+a destination null-padded character sequence in a fixed-size buffer.
+If the destination buffer,
+limited by its size,
+isn't large enough to hold the copy,
+the resulting character sequence is truncated.
+Since it creates a character sequence,
+it doesn't need to write a terminating null character.
+It's impossible to distinguish truncation by the result of the call,
+from a character sequence that just fits the destination buffer;
+truncation should be detected by
+comparing the length of the input string
+with the size of the destination buffer.
+.\" ----- DESCRIPTION :: Functions :: strncpy(3) ----------------------/
+.TP
+.BR strncpy (3)
+This function is identical to
+.BR stpncpy (3)
+except for the useless return value.
+.IP
+.BR stpncpy (3)
+is a more useful alternative to this function.
+.\" ----- DESCRIPTION :: Functions :: strncat(3) ----------------------/
+.TP
+.BR strncat (3)
+Catenate the input character sequence,
+contained in a null-padded fixed-size buffer,
+into a destination string.
+The programmer is responsible for allocating a buffer large enough.
+The return value is useless.
+.IP
+Do not confuse this function with
+.BR strncpy (3);
+they are not related at all.
+.IP
+.I \%stpcpy(mempcpy(dst,\ src,\ strnlen(src,\ NITEMS(src))),\ \[dq]\[dq])
+is a faster alternative to this function.
+.\" ----- DESCRIPTION :: Functions :: mempcpy(3) ----------------------/
+.TP
+.BR mempcpy (3)
+Copy the input character sequence,
+limited by its length,
+into a destination character sequence.
+The programmer is responsible for allocating a buffer large enough.
+It returns a pointer suitable for chaining.
+.\" ----- RETURN VALUE :: ---------------------------------------------/
+.SH RETURN VALUE
+.TP
+.BR stpcpy (3)
+A pointer to the terminating null character in the destination string.
+.TP
+.BR stpecpy ()
+A pointer to the terminating null character in the destination string,
+on success.
+On error,
+NULL is returned,
+and
+.I errno
+is set to indicate the error.
+.TP
+.BR mempcpy (3)
+.TQ
+.BR stpncpy (3)
+A pointer to one after the last character
+in the destination character sequence.
+.TP
+.BR strtcpy ()
+The length of the string,
+on success.
+On error,
+\-1 is returned,
+and
+.I errno
+is set to indicate the error.
+.TP
+.BR strlcpy (3bsd)
+.TQ
+.BR strlcat (3bsd)
+The length of the total string that they tried to create
+(as if truncation didn't occur).
+.TP
+.BR strcpy (3)
+.TQ
+.BR strcat (3)
+.TQ
+.BR strncpy (3)
+.TQ
+.BR strncat (3)
+The
+.I dst
+pointer,
+which is useless.
+.\" ----- ERRORS ------------------------------------------------------/
+.SH ERRORS
+Most of these functions don't set
+.IR errno .
+.TP
+.BR stpecpy ()
+.TQ
+.BR strtcpy ()
+.RS
+.TP
+.B ENOBUFS
+.I dsize
+was
+.BR 0 .
+.TP
+.B E2BIG
+The string has been truncated.
+.RE
+.\" ----- NOTES :: strscpy(9) -----------------------------------------/
+.SH NOTES
+The Linux kernel has an internal function for copying strings,
+.BR strscpy (9),
+which is identical to
+.BR strtcpy (),
+except that it returns
+.B \-E2BIG
+instead of \-1
+and it doesn't set
+.IR errno .
+.\" ----- CAVEATS :: --------------------------------------------------/
+.SH CAVEATS
+Don't mix chain calls to truncating and non-truncating functions.
+It is conceptually wrong
+unless you know that the first part of a copy will always fit.
+Anyway, the performance difference will probably be negligible,
+so it will probably be more clear if you use consistent semantics:
+either truncating or non-truncating.
+Calling a non-truncating function after a truncating one is necessarily wrong.
+.\" ----- BUGS :: -----------------------------------------------------/
+.SH BUGS
+All catenation functions share the same performance problem:
+.UR https://www.joelonsoftware.com/\:2001/12/11/\:back\-to\-basics/
+Shlemiel the painter
+.UE .
+As a mitigation,
+compilers are able to transform some calls to catenation functions
+into normal copy functions,
+since
+.I strlen(dst)
+is usually a byproduct of the previous copy.
+.P
+.BR strlcpy (3)
+and
+.BR strlcat (3)
+need to read the entire
+.I src
+string,
+even if the destination buffer is small.
+This makes them vulnerable to Denial of Service (DoS) attacks
+if an attacker can control the length of the
+.I src
+string.
+And if not,
+they're still unnecessarily slow.
+.\" ----- EXAMPLES :: -------------------------------------------------/
+.SH EXAMPLES
+The following are examples of correct use of each of these functions.
+.\" ----- EXAMPLES :: stpcpy(3) ---------------------------------------/
+.TP
+.BR stpcpy (3)
+.EX
+p = buf;
+p = stpcpy(p, "Hello ");
+p = stpcpy(p, "world");
+p = stpcpy(p, "!");
+len = p \- buf;
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: strcpy(3), strcat(3) ----------------------------/
+.TP
+.BR strcpy (3)
+.TQ
+.BR strcat (3)
+.EX
+strcpy(buf, "Hello ");
+strcat(buf, "world");
+strcat(buf, "!");
+len = strlen(buf);
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: stpecpy() ---------------------------------------/
+.TP
+.BR stpecpy ()
+.EX
+end = buf + NITEMS(buf);
+p = buf;
+p = stpecpy(p, end, "Hello ");
+p = stpecpy(p, end, "world");
+p = stpecpy(p, end, "!");
+if (p == NULL) {
+    len = NITEMS(buf) \- 1;
+    goto toolong;
+}
+len = p \- buf;
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: strtcpy() ---------------------------------------/
+.TP
+.BR strtcpy ()
+.EX
+len = strtcpy(buf, "Hello world!", NITEMS(buf));
+if (len == \-1)
+    goto toolong;
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: strlcpy(3bsd), strlcat(3bsd) --------------------/
+.TP
+.BR strlcpy (3bsd)
+.TQ
+.BR strlcat (3bsd)
+.EX
+if (strlcpy(buf, "Hello ", NITEMS(buf)) >= NITEMS(buf))
+    goto toolong;
+if (strlcat(buf, "world", NITEMS(buf)) >= NITEMS(buf))
+    goto toolong;
+len = strlcat(buf, "!", NITEMS(buf));
+if (len >= NITEMS(buf))
+    goto toolong;
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: stpncpy(3) --------------------------------------/
+.TP
+.BR stpncpy (3)
+.EX
+p = stpncpy(u->ut_user, "alx", NITEMS(u->ut_user));
+if (NITEMS(u->ut_user) < strlen("alx"))
+    goto toolong;
+len = p \- u->ut_user;
+fwrite(u->ut_user, 1, len, stdout);
+.EE
+.\" ----- EXAMPLES :: strncpy(3) --------------------------------------/
+.TP
+.BR strncpy (3)
+.EX
+strncpy(u->ut_user, "alx", NITEMS(u->ut_user));
+if (NITEMS(u->ut_user) < strlen("alx"))
+    goto toolong;
+len = strnlen(u->ut_user, NITEMS(u->ut_user));
+fwrite(u->ut_user, 1, len, stdout);
+.EE
+.\" ----- EXAMPLES :: mempcpy(dst, src, strnlen(src, NITEMS(src))) ----/
+.TP
+.I mempcpy(dst, src, strnlen(src, NITEMS(src)))
+.EX
+char  buf[NITEMS(u->ut_user)];
+p = buf;
+p = mempcpy(p, u->ut_user, strnlen(u->ut_user, NITEMS(u->ut_user)));
+len = p \- buf;
+fwrite(buf, 1, len, stdout);
+.EE
+.\" ----- EXAMPLES :: stpcpy(mempcpy(dst, src, strnlen(src, NITEMS(src))), "")
+.TP
+.I stpcpy(mempcpy(dst, src, strnlen(src, NITEMS(src))), \[dq]\[dq])
+.EX
+char  buf[NITEMS(u->ut_user) + 1];
+p = buf;
+p = mempcpy(p, u->ut_user, strnlen(u->ut_user, NITEMS(u->ut_user)));
+p = stpcpy(p, "");
+len = p \- buf;
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: strncat(3) --------------------------------------/
+.TP
+.BR strncat (3)
+.EX
+char  buf[NITEMS(u->ut_user) + 1];
+strcpy(buf, "");
+strncat(buf, u->ut_user, NITEMS(u->ut_user));
+len = strlen(buf);
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: mempcpy(3) --------------------------------------/
+.TP
+.BR mempcpy (3)
+.EX
+p = buf;
+p = mempcpy(p, "Hello ", 6);
+p = mempcpy(p, "world", 5);
+p = mempcpy(p, "!", 1);
+len = p \- buf;
+fwrite(buf, 1, len, stdout);
+.EE
+.\" ----- EXAMPLES :: stpcpy(mempcpy(), "") ---------------------------/
+.TP
+.I stpcpy(mempcpy(dst, src, len), \[dq]\[dq])
+.EX
+p = buf;
+p = mempcpy(p, "Hello ", 6);
+p = mempcpy(p, "world", 5);
+p = mempcpy(p, "!", 1);
+p = stpcpy(p, "");
+len = p \- buf;
+puts(buf);
+.EE
+.\" ----- EXAMPLES :: Implementations :: ------------------------------/
+.SS Implementations
+Here are reference implementations for functions not provided by libc.
+.P
+.in +4n
+.EX
+/* This code is in the public domain. */
+\&
+.\" ----- EXAMPLES :: Implementations :: stpecpy() --------------------/
+char *
+.IR stpecpy "(char *dst, char end[0], const char *restrict src)"
+{
+    size_t  dlen;
+\&
+    if (dst == NULL)
+        return NULL;
+\&
+    dlen = strtcpy(dst, src, end \- dst);
+    return (dlen == \-1) ? NULL : dst + dlen;
+}
+\&
+.\" ----- EXAMPLES :: Implementations :: strtcpy() --------------------/
+ssize_t
+.IR strtcpy "(char *restrict dst, const char *restrict src, size_t dsize)"
+{
+    bool    trunc;
+    size_t  dlen, slen;
+\&
+    if (dsize == 0) {
+        errno = ENOBUFS;
+        return \-1;
+    }
+\&
+    slen = strnlen(src, dsize);
+    trunc = (slen == dsize);
+    dlen = slen \- trunc;
+\&
+    stpcpy(mempcpy(dst, src, dlen), "");
+    if (trunc)
+        errno = E2BIG;
+    return trunc ? \-1 : slen;
+}
+.\" ----- SEE ALSO :: -------------------------------------------------/
+.SH SEE ALSO
+.BR bzero (3),
+.BR memcpy (3),
+.BR memccpy (3),
+.BR mempcpy (3),
+.BR stpcpy (3),
+.BR strlcpy (3bsd),
+.BR strncat (3),
+.BR stpncpy (3),
+.BR string (3)
diff --git a/man/man7/suffixes.7 b/man/man7/suffixes.7
new file mode 100644
index 000000000..657f82cde
--- /dev/null
+++ b/man/man7/suffixes.7
@@ -0,0 +1,265 @@
+'\" t
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Modified Sat Jul 24 17:35:15 1993 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Sun Feb 19 22:02:32 1995 by Rik Faith <faith@cs.unc.edu>
+.\" Modified Tue Oct 22 23:28:12 1996 by Eric S. Raymond <esr@thyrsus.com>
+.\" Modified Sun Jan 26 21:56:56 1997 by Ralph Schleicher
+.\"    <rs@purple.UL.BaWue.DE>
+.\" Modified Mon Jun 16 20:24:58 1997 by Nicolás Lichtmaier <nick@debian.org>
+.\" Modified Sun Oct 18 22:11:28 1998 by Joseph S. Myers <jsm28@cam.ac.uk>
+.\" Modified Mon Nov 16 17:24:47 1998 by Andries Brouwer <aeb@cwi.nl>
+.\" Modified Thu Nov 16 23:28:25 2000 by David A. Wheeler
+.\"    <dwheeler@dwheeler.com>
+.\"
+.TH SUFFIXES 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+suffixes \- list of file suffixes
+.SH DESCRIPTION
+It is customary to indicate the contents of a file with the file suffix,
+which (typically) consists of a period, followed by one or more letters.
+Many standard utilities, such as compilers, use this to recognize the type of
+file they are dealing with.
+The
+.BR make (1)
+utility is driven by rules based on file suffix.
+.P
+Following is a list of suffixes which are likely to be found on a
+Linux system.
+.P
+.TS
+l | l
+_ | _
+lI |  l .
+Suffix	File type
+\&,v	files for RCS (Revision Control System)
+\&-	backup file
+\&.C	C++ source code, equivalent to \fI.cc\fP
+\&.F	Fortran source with \fBcpp\fP(1) directives
+\&	or file compressed using freeze
+\&.S	assembler source with \fBcpp\fP(1) directives
+\&.Y	file compressed using yabba
+\&.Z	file compressed using \fBcompress\fP(1)
+\&.[0\-9]+gf	TeX generic font files
+\&.[0\-9]+pk	TeX packed font files
+\&.[1\-9]	manual page for the corresponding section
+\&.[1\-9][a-z]	manual page for section plus subsection
+\&.a	static object code library
+\&.ad	X application default resource file
+\&.ada	Ada source (may be body, spec, or combination)
+\&.adb	Ada body source
+\&.ads	Ada spec source
+\&.afm	PostScript font metrics
+\&.al	Perl autoload file
+\&.am	\fBautomake\fP(1) input file
+\&.arc	\fBarc\fP(1) archive
+\&.arj	\fBarj\fP(1) archive
+\&.asc	PGP ASCII-armored data
+\&.asm	(GNU) assembler source file
+\&.au	Audio sound file
+\&.aux	LaTeX auxiliary file
+\&.avi	(msvideo) movie
+\&.awk	AWK language program
+\&.b	LILO boot loader image
+\&.bak	backup file
+\&.bash	\fBbash\fP(1) shell script
+\&.bb	basic block list data produced by
+\&	gcc \-ftest\-coverage
+\&.bbg	basic block graph data produced by
+\&	gcc \-ftest\-coverage
+\&.bbl	BibTeX output
+\&.bdf	X font file
+\&.bib	TeX bibliographic database, BibTeX input
+\&.bm	bitmap source
+\&.bmp	bitmap
+\&.bz2	file compressed using \fBbzip2\fP(1)
+\&.c	C source
+\&.cat	message catalog files
+\&.cc	C++ source
+\&.cf	configuration file
+\&.cfg	configuration file
+\&.cgi	WWW content generating script or program
+\&.cls	LaTeX Class definition
+\&.class	Java compiled byte-code
+\&.conf	configuration file
+\&.config	configuration file
+\&.cpp	equivalent to \fI.cc\fR
+\&.csh	\fBcsh\fP(1) shell script
+\&.cxx	equivalent to \fI.cc\fR
+\&.dat	data file
+\&.deb	Debian software package
+\&.def	Modula-2 source for definition modules
+\&.def	other definition files
+\&.desc	initial part of mail message unpacked with
+\&	\fBmunpack\fP(1)
+\&.diff	file differences (\fBdiff\fP(1) command output)
+\&.dir	dbm data base directory file
+\&.doc	documentation file
+\&.dsc	Debian Source Control (source package)
+\&.dtx	LaTeX package source file
+\&.dvi	TeX's device independent output
+\&.el	Emacs-Lisp source
+\&.elc	compiled Emacs-Lisp source
+\&.eps	encapsulated PostScript
+\&.exp	Expect source code
+\&.f	Fortran source
+\&.f77	Fortran 77 source
+\&.f90	Fortran 90 source
+\&.fas	precompiled Common-Lisp
+\&.fi	Fortran include files
+\&.fig	FIG image file (used by \fBxfig\fP(1))
+\&.fmt	TeX format file
+\&.gif	Compuserve Graphics Image File format
+\&.gmo	GNU format message catalog
+\&.gsf	Ghostscript fonts
+\&.gz	file compressed using \fBgzip\fP(1)
+\&.h	C or C++ header files
+\&.help	help file
+\&.hf	equivalent to \fI.help\fP
+\&.hlp	equivalent to \fI.help\fP
+\&.htm	poor man's \fI.html\fP
+\&.html	HTML document used with the World Wide Web
+\&.hqx	7-bit encoded Macintosh file
+\&.i	C source after preprocessing
+\&.icon	bitmap source
+\&.idx	reference or datum-index file for hypertext
+\&	or database system
+\&.image	bitmap source
+\&.in	configuration template, especially for GNU Autoconf
+\&.info	files for the Emacs info browser
+\&.info-[0\-9]+	split info files
+\&.ins	LaTeX package install file for docstrip
+\&.itcl	itcl source code;
+\&	itcl ([incr Tcl]) is an OO extension of tcl
+\&.java	a Java source file
+\&.jpeg	Joint Photographic Experts Group format
+\&.jpg	poor man's \fI.jpeg\fP
+\&.js	JavaScript source code
+\&.jsx	JSX (JavaScript XML-like extension) source code
+\&.kmap	\fBlyx\fP(1) keymap
+\&.l	equivalent to \fI.lex\fP or \fI.lisp\fP
+\&.lex	\fBlex\fP(1) or \fBflex\fP(1) files
+\&.lha	lharc archive
+\&.lib	Common-Lisp library
+\&.lisp	Lisp source
+\&.ln	files for use with \fBlint\fP(1)
+\&.log	log file, in particular produced by TeX
+\&.lsm	Linux Software Map entry
+\&.lsp	Common-Lisp source
+\&.lzh	lharc archive
+\&.m	Objective-C source code
+\&.m4	\fBm4\fP(1) source
+\&.mac	macro files for various programs
+\&.man	manual page (usually source rather than formatted)
+\&.map	map files for various programs
+\&.me	Nroff source using the me macro package
+\&.mf	Metafont (font generator for TeX) source
+\&.mgp	MagicPoint file
+\&.mm	sources for \fBgroff\fP(1) in mm - format
+\&.mo	Message catalog binary file
+\&.mod	Modula-2 source for implementation modules
+\&.mov	(quicktime) movie
+\&.mp	Metapost source
+\&.mp2	MPEG Layer 2 (audio) file
+\&.mp3	MPEG Layer 3 (audio) file
+\&.mpeg	movie file
+\&.o	object file
+\&.old	old or backup file
+\&.orig	backup (original) version of a file, from \fBpatch\fP(1)
+\&.out	output file, often executable program (a.out)
+\&.p	Pascal source
+\&.pag	dbm data base data file
+\&.patch	file differences for \fBpatch\fP(1)
+\&.pbm	portable bitmap format
+\&.pcf	X11 font files
+\&.pdf	Adobe Portable Data Format
+\&	(use Acrobat/\fBacroread\fP or \fBxpdf\fP)
+\&.perl	Perl source (see .ph, .pl, and .pm)
+\&.pfa	PostScript font definition files, ASCII format
+\&.pfb	PostScript font definition files, binary format
+\&.pgm	portable greymap format
+\&.pgp	PGP binary data
+\&.ph	Perl header file
+\&.php	PHP program file
+\&.php3	PHP3 program file
+\&.pid	File to store daemon PID (e.g., crond.pid)
+\&.pl	TeX property list file or Perl library file
+\&.pm	Perl module
+\&.png	Portable Network Graphics file
+\&.po	Message catalog source
+\&.pod	\fBperldoc\fP(1) file
+\&.ppm	portable pixmap format
+\&.pr	bitmap source
+\&.ps	PostScript file
+\&.py	Python source
+\&.pyc	compiled python
+\&.qt	quicktime movie
+\&.r	RATFOR source (obsolete)
+\&.rej	patches that \fBpatch\fP(1) couldn't apply
+\&.rpm	RPM software package
+\&.rtf	Rich Text Format file
+\&.rules	rules for something
+\&.s	assembler source
+\&.sa	stub libraries for a.out shared libraries
+\&.sc	\fBsc\fP(1) spreadsheet commands
+\&.scm	Scheme source code
+\&.sed	sed source file
+\&.sgml	SGML source file
+\&.sh	\fBsh\fP(1) scripts
+\&.shar	archive created by the \fBshar\fP(1) utility
+\&.shtml	HTML using Server Side Includes
+\&.so	Shared library or dynamically loadable object
+\&.sql	SQL source
+\&.sqml	SQML schema or query program
+\&.sty	LaTeX style files
+\&.sym	Modula-2 compiled definition modules
+\&.tar	archive created by the \fBtar\fP(1) utility
+\&.tar.Z	tar(1) archive compressed with \fBcompress\fP(1)
+\&.tar.bz2	tar(1) archive compressed with \fBbzip2\fP(1)
+\&.tar.gz	tar(1) archive compressed with \fBgzip\fP(1)
+\&.taz	tar(1) archive compressed with \fBcompress\fP(1)
+\&.tcl	tcl source code
+\&.tex	TeX or LaTeX source
+\&.texi	equivalent to \fI.texinfo\fP
+\&.texinfo	Texinfo documentation source
+\&.text	text file
+\&.tfm	TeX font metric file
+\&.tgz	tar archive compressed with \fBgzip\fP(1)
+\&.tif	poor man's \fI.tiff\fP
+\&.tiff	Tagged Image File Format
+\&.tk	tcl/tk script
+\&.tmp	temporary file
+\&.tmpl	template files
+\&.ts	TypeScript source code
+\&.tsx	TypeScript with JSX source code (\fI.ts\fP + \fI.jsx\fP)
+\&.txt	equivalent to \fI.text\fP
+\&.uu	equivalent to \fI.uue\fP
+\&.uue	binary file encoded with \fBuuencode\fP(1)
+\&.vf	TeX virtual font file
+\&.vpl	TeX virtual property list file
+\&.w	Silvio Levi's CWEB
+\&.wav	wave sound file
+\&.web	Donald Knuth's WEB
+\&.wml	Source file for Web Meta Language
+\&.xbm	X11 bitmap source
+\&.xcf	GIMP graphic
+\&.xml	eXtended Markup Language file
+\&.xpm	X11 pixmap source
+\&.xs	Perl xsub file produced by h2xs
+\&.xsl	XSL stylesheet
+\&.y	\fByacc\fP(1) or \fBbison\fP(1) (parser generator) files
+\&.z	File compressed using \fBpack\fP(1) (or an old \fBgzip\fP(1))
+\&.zip	\fBzip\fP(1) archive
+\&.zoo	\fBzoo\fP(1) archive
+\&\[ti]	Emacs or \fBpatch\fP(1) backup file
+\&rc	startup (`run control') file, e.g., \fI.newsrc\fP
+.TE
+.SH STANDARDS
+General UNIX conventions.
+.SH BUGS
+This list is not exhaustive.
+.SH SEE ALSO
+.BR file (1),
+.BR make (1)
diff --git a/man/man7/svipc.7 b/man/man7/svipc.7
new file mode 100644
index 000000000..cc543f5c3
--- /dev/null
+++ b/man/man7/svipc.7
@@ -0,0 +1 @@
+.so man7/sysvipc.7
diff --git a/man/man7/symlink.7 b/man/man7/symlink.7
new file mode 100644
index 000000000..5aaaee598
--- /dev/null
+++ b/man/man7/symlink.7
@@ -0,0 +1,564 @@
+.\" Copyright (c) 1992, 1993, 1994
+.\"	The Regents of the University of California.  All rights reserved.
+.\" and Copyright (C) 2008, 2014 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\"	@(#)symlink.7	8.3 (Berkeley) 3/31/94
+.\" $FreeBSD: src/bin/ln/symlink.7,v 1.30 2005/02/13 22:25:09 ru Exp $
+.\"
+.\" 2008-06-11, mtk, Taken from FreeBSD 6.2 and heavily edited for
+.\"     specific Linux details, improved readability, and man-pages style.
+.\"
+.TH symlink 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+symlink \- symbolic link handling
+.SH DESCRIPTION
+Symbolic links are files that act as pointers to other files.
+To understand their behavior, you must first understand how hard links
+work.
+.P
+A hard link to a file is indistinguishable from the original file because
+it is a reference to the object underlying the original filename.
+(To be precise: each of the hard links to a file is a reference to
+the same
+.IR "inode number" ,
+where an inode number is an index into the inode table,
+which contains metadata about all files on a filesystem.
+See
+.BR stat (2).)
+Changes to a file are independent of the name used to reference the file.
+Hard links may not refer to directories
+(to prevent the possibility of loops within the filesystem tree,
+which would confuse many programs)
+and may not refer to files on different filesystems
+(because inode numbers are not unique across filesystems).
+.P
+A symbolic link is a special type of file whose contents are a string
+that is the pathname of another file, the file to which the link refers.
+(The contents of a symbolic link can be read using
+.BR readlink (2).)
+In other words, a symbolic link is a pointer to another name,
+and not to an underlying object.
+For this reason, symbolic links may refer to directories and may cross
+filesystem boundaries.
+.P
+There is no requirement that the pathname referred to by a symbolic link
+should exist.
+A symbolic link that refers to a pathname that does not exist is said
+to be a
+.IR "dangling link" .
+.P
+Because a symbolic link and its referenced object coexist in the filesystem
+name space, confusion can arise in distinguishing between the link itself
+and the referenced object.
+On historical systems,
+commands and system calls adopted their own link-following
+conventions in a somewhat ad-hoc fashion.
+Rules for a more uniform approach,
+as they are implemented on Linux and other systems,
+are outlined here.
+It is important that site-local applications also conform to these rules,
+so that the user interface can be as consistent as possible.
+.\"
+.SS Magic links
+There is a special class of symbolic-link-like objects
+known as "magic links", which
+can be found in certain pseudofilesystems such as
+.BR proc (5)
+(examples include
+.IR /proc/ pid /exe
+and
+.IR /proc/ pid /fd/ *).
+Unlike normal symbolic links, magic links are not resolved through
+pathname-expansion, but instead act as direct references to the kernel's own
+representation of a file handle.
+As such, these magic links allow users to
+access files which cannot be referenced with normal paths (such as unlinked
+files still referenced by a running program ).
+.P
+Because they can bypass ordinary
+.BR mount_namespaces (7)-based
+restrictions,
+magic links have been used as attack vectors in various exploits.
+.\"
+.SS Symbolic link ownership, permissions, and timestamps
+The owner and group of an existing symbolic link can be changed
+using
+.BR lchown (2).
+The ownership of a symbolic link matters
+when the link is being removed or renamed in a directory that
+has the sticky bit set (see
+.BR inode (7)),
+and when the
+.I fs.protected_symlinks
+sysctl is set (see
+.BR proc (5)).
+.P
+The last access and last modification timestamps
+of a symbolic link can be changed using
+.BR utimensat (2)
+or
+.BR lutimes (3).
+.P
+.\" Linux does not currently implement an lchmod(2).
+On Linux, the permissions of an ordinary symbolic link are not used in any
+operations; the permissions are always 0777 (read, write, and execute for all
+user categories), and can't be changed.
+.P
+However, magic links do not follow this rule.
+They can have a non-0777 mode,
+though this mode is not currently used in any permission checks.
+.\" .P
+.\" The
+.\" 4.4BSD
+.\" system differs from historical
+.\" 4BSD
+.\" systems in that the system call
+.\" .BR chown (2)
+.\" has been changed to follow symbolic links.
+.\" The
+.\" .BR lchown (2)
+.\" system call was added later when the limitations of the new
+.\" .BR chown (2)
+.\" became apparent.
+.SS Obtaining a file descriptor that refers to a symbolic link
+Using the combination of the
+.B O_PATH
+and
+.B O_NOFOLLOW
+flags to
+.BR open (2)
+yields a file descriptor that can be passed as the
+.I dirfd
+argument in system calls such as
+.BR fstatat (2),
+.BR fchownat (2),
+.BR fchmodat (2),
+.BR linkat (2),
+and
+.BR readlinkat (2),
+in order to operate on the symbolic link itself
+(rather than the file to which it refers).
+.P
+By default
+(i.e., if the
+.B AT_SYMLINK_FOLLOW
+flag is not specified), if
+.BR name_to_handle_at (2)
+is applied to a symbolic link, it yields a handle for the symbolic link
+(rather than the file to which it refers).
+One can then obtain a file descriptor for the symbolic link
+(rather than the file to which it refers)
+by specifying the
+.B O_PATH
+flag in a subsequent call to
+.BR open_by_handle_at (2).
+Again, that file descriptor can be used in the
+aforementioned system calls to operate on the symbolic link itself.
+.SS Handling of symbolic links by system calls and commands
+Symbolic links are handled either by operating on the link itself,
+or by operating on the object referred to by the link.
+In the latter case,
+an application or system call is said to
+.I follow
+the link.
+Symbolic links may refer to other symbolic links,
+in which case the links are dereferenced until an object that is
+not a symbolic link is found,
+a symbolic link that refers to a file which does not exist is found,
+or a loop is detected.
+(Loop detection is done by placing an upper limit on the number of
+links that may be followed, and an error results if this limit is
+exceeded.)
+.P
+There are three separate areas that need to be discussed.
+They are as follows:
+.IP \[bu] 3
+Symbolic links used as filename arguments for system calls.
+.IP \[bu]
+Symbolic links specified as command-line arguments to utilities that
+are not traversing a file tree.
+.IP \[bu]
+Symbolic links encountered by utilities that are traversing a file tree
+(either specified on the command line or encountered as part of the
+file hierarchy walk).
+.P
+Before describing the treatment of symbolic links by system calls and commands,
+we require some terminology.
+Given a pathname of the form
+.IR a/b/c ,
+the part preceding the final slash (i.e.,
+.IR a/b )
+is called the
+.I dirname
+component, and the part following the final slash (i.e.,
+.IR c )
+is called the
+.I basename
+component.
+.\"
+.SS Treatment of symbolic links in system calls
+The first area is symbolic links used as filename arguments for
+system calls.
+.P
+The treatment of symbolic links within a pathname passed to
+a system call is as follows:
+.IP (1) 5
+Within the dirname component of a pathname,
+symbolic links are always followed in nearly every system call.
+(This is also true for commands.)
+The one exception is
+.BR openat2 (2),
+which provides flags that can be used to explicitly
+prevent following of symbolic links in the dirname component.
+.IP (2)
+Except as noted below,
+all system calls follow symbolic links
+in the basename component of a pathname.
+For example, if there were a symbolic link
+.I slink
+which pointed to a file named
+.IR afile ,
+the system call
+.I "open(""slink"" ...\&)"
+would return a file descriptor referring to the file
+.IR afile .
+.P
+Various system calls do not follow links in
+the basename component of a pathname,
+and operate on the symbolic link itself.
+They are:
+.BR lchown (2),
+.BR lgetxattr (2),
+.BR llistxattr (2),
+.BR lremovexattr (2),
+.BR lsetxattr (2),
+.BR lstat (2),
+.BR readlink (2),
+.BR rename (2),
+.BR rmdir (2),
+and
+.BR unlink (2).
+.P
+Certain other system calls optionally follow symbolic links
+in the basename component of a pathname.
+They are:
+.BR faccessat (2),
+.\" Maybe one day: .BR fchownat (2)
+.BR fchownat (2),
+.BR fstatat (2),
+.BR linkat (2),
+.BR name_to_handle_at (2),
+.BR open (2),
+.BR openat (2),
+.BR open_by_handle_at (2),
+and
+.BR utimensat (2);
+see their manual pages for details.
+Because
+.BR remove (3)
+is an alias for
+.BR unlink (2),
+that library function also does not follow symbolic links.
+When
+.BR rmdir (2)
+is applied to a symbolic link, it fails with the error
+.BR ENOTDIR .
+.P
+.BR link (2)
+warrants special discussion.
+POSIX.1-2001 specifies that
+.BR link (2)
+should dereference
+.I oldpath
+if it is a symbolic link.
+However, Linux does not do this.
+(By default, Solaris is the same,
+but the POSIX.1-2001 specified behavior can be obtained with
+suitable compiler options.)
+POSIX.1-2008 changed the specification to allow
+either behavior in an implementation.
+.SS Commands not traversing a file tree
+The second area is symbolic links, specified as command-line
+filename arguments, to commands which are not traversing a file tree.
+.P
+Except as noted below, commands follow symbolic links named as
+command-line arguments.
+For example, if there were a symbolic link
+.I slink
+which pointed to a file named
+.IR afile ,
+the command
+.I "cat slink"
+would display the contents of the file
+.IR afile .
+.P
+It is important to realize that this rule includes commands which may
+optionally traverse file trees; for example, the command
+.I "chown file"
+is included in this rule, while the command
+.IR "chown\ \-R file" ,
+which performs a tree traversal, is not.
+(The latter is described in the third area, below.)
+.P
+If it is explicitly intended that the command operate on the symbolic
+link instead of following the symbolic link\[em]for example, it is desired that
+.I "chown slink"
+change the ownership of the file that
+.I slink
+is, whether it is a symbolic link or not\[em]then the
+.I \-h
+option should be used.
+In the above example,
+.I "chown root slink"
+would change the ownership of the file referred to by
+.IR slink ,
+while
+.I "chown\ \-h root slink"
+would change the ownership of
+.I slink
+itself.
+.P
+There are some exceptions to this rule:
+.IP \[bu] 3
+The
+.BR mv (1)
+and
+.BR rm (1)
+commands do not follow symbolic links named as arguments,
+but respectively attempt to rename and delete them.
+(Note, if the symbolic link references a file via a relative path,
+moving it to another directory may very well cause it to stop working,
+since the path may no longer be correct.)
+.IP \[bu]
+The
+.BR ls (1)
+command is also an exception to this rule.
+For compatibility with historic systems (when
+.BR ls (1)
+is not doing a tree walk\[em]that is,
+.I \-R
+option is not specified),
+the
+.BR ls (1)
+command follows symbolic links named as arguments if the
+.I \-H
+or
+.I \-L
+option is specified,
+or if the
+.IR \-F ,
+.IR \-d ,
+or
+.I \-l
+options are not specified.
+(The
+.BR ls (1)
+command is the only command where the
+.I \-H
+and
+.I \-L
+options affect its behavior even though it is not doing a walk of
+a file tree.)
+.IP \[bu]
+The
+.BR file (1)
+command is also an exception to this rule.
+The
+.BR file (1)
+command does not follow symbolic links named as argument by default.
+The
+.BR file (1)
+command does follow symbolic links named as argument if the
+.I \-L
+option is specified.
+.\"
+.\"The 4.4BSD system differs from historical 4BSD systems in that the
+.\".BR chown (1)
+.\"and
+.\".BR chgrp (1)
+.\"commands follow symbolic links specified on the command line.
+.SS Commands traversing a file tree
+The following commands either optionally or always traverse file trees:
+.BR chgrp (1),
+.BR chmod (1),
+.BR chown (1),
+.BR cp (1),
+.BR du (1),
+.BR find (1),
+.BR ls (1),
+.BR pax (1),
+.BR rm (1),
+and
+.BR tar (1).
+.P
+It is important to realize that the following rules apply equally to
+symbolic links encountered during the file tree traversal and symbolic
+links listed as command-line arguments.
+.P
+The \fIfirst rule\fP applies to symbolic links that reference files other
+than directories.
+Operations that apply to symbolic links are performed on the links
+themselves, but otherwise the links are ignored.
+.P
+The command
+.I "rm\ \-r slink directory"
+will remove
+.IR slink ,
+as well as any symbolic links encountered in the tree traversal of
+.IR directory ,
+because symbolic links may be removed.
+In no case will
+.BR rm (1)
+affect the file referred to by
+.IR slink .
+.P
+The \fIsecond rule\fP applies to symbolic links that refer to directories.
+Symbolic links that refer to directories are never followed by default.
+This is often referred to as a "physical" walk, as opposed to a "logical"
+walk (where symbolic links that refer to directories are followed).
+.P
+Certain conventions are (should be) followed as consistently as
+possible by commands that perform file tree walks:
+.IP \[bu] 3
+A command can be made to follow
+any symbolic links named on the command line,
+regardless of the type of file they reference, by specifying the
+.I \-H
+(for "half-logical") flag.
+This flag is intended to make the command-line name space look
+like the logical name space.
+(Note, for commands that do not always do file tree traversals, the
+.I \-H
+flag will be ignored if the
+.I \-R
+flag is not also specified.)
+.IP
+For example, the command
+.I "chown\ \-HR user slink"
+will traverse the file hierarchy rooted in the file pointed to by
+.IR slink .
+Note, the
+.I \-H
+is not the same as the previously discussed
+.I \-h
+flag.
+The
+.I \-H
+flag causes symbolic links specified on the command line to be
+dereferenced for the purposes of both the action to be performed
+and the tree walk, and it is as if the user had specified the
+name of the file to which the symbolic link pointed.
+.IP \[bu]
+A command can be made to
+follow any symbolic links named on the command line,
+as well as any symbolic links encountered during the traversal,
+regardless of the type of file they reference, by specifying the
+.I \-L
+(for "logical") flag.
+This flag is intended to make the entire name space look like
+the logical name space.
+(Note, for commands that do not always do file tree traversals, the
+.I \-L
+flag will be ignored if the
+.I \-R
+flag is not also specified.)
+.IP
+For example, the command
+.I "chown\ \-LR user slink"
+will change the owner of the file referred to by
+.IR slink .
+If
+.I slink
+refers to a directory,
+.B chown
+will traverse the file hierarchy rooted in the directory that it
+references.
+In addition, if any symbolic links are encountered in any file tree that
+.B chown
+traverses, they will be treated in the same fashion as
+.IR slink .
+.IP \[bu]
+A command can be made to
+provide the default behavior by specifying the
+.I \-P
+(for "physical") flag.
+This flag is intended to make the entire name space look like the
+physical name space.
+.P
+For commands that do not by default do file tree traversals, the
+.IR \-H ,
+.IR \-L ,
+and
+.I \-P
+flags are ignored if the
+.I \-R
+flag is not also specified.
+In addition, you may specify the
+.IR \-H ,
+.IR \-L ,
+and
+.I \-P
+options more than once;
+the last one specified determines the command's behavior.
+This is intended to permit you to alias commands to behave one way
+or the other, and then override that behavior on the command line.
+.P
+The
+.BR ls (1)
+and
+.BR rm (1)
+commands have exceptions to these rules:
+.IP \[bu] 3
+The
+.BR rm (1)
+command operates on the symbolic link, and not the file it references,
+and therefore never follows a symbolic link.
+The
+.BR rm (1)
+command does not support the
+.IR \-H ,
+.IR \-L ,
+or
+.I \-P
+options.
+.IP \[bu]
+To maintain compatibility with historic systems,
+the
+.BR ls (1)
+command acts a little differently.
+If you do not specify the
+.IR \-F ,
+.IR \-d ,
+or
+.I \-l
+options,
+.BR ls (1)
+will follow symbolic links specified on the command line.
+If the
+.I \-L
+flag is specified,
+.BR ls (1)
+follows all symbolic links,
+regardless of their type,
+whether specified on the command line or encountered in the tree walk.
+.SH SEE ALSO
+.BR chgrp (1),
+.BR chmod (1),
+.BR find (1),
+.BR ln (1),
+.BR ls (1),
+.BR mv (1),
+.BR namei (1),
+.BR rm (1),
+.BR lchown (2),
+.BR link (2),
+.BR lstat (2),
+.BR readlink (2),
+.BR rename (2),
+.BR symlink (2),
+.BR unlink (2),
+.BR utimensat (2),
+.BR lutimes (3),
+.BR path_resolution (7)
diff --git a/man/man7/system_data_types.7 b/man/man7/system_data_types.7
new file mode 100644
index 000000000..59180cff2
--- /dev/null
+++ b/man/man7/system_data_types.7
@@ -0,0 +1,242 @@
+.\" Copyright (c) 2020 by Alejandro Colomar <alx@kernel.org>
+.\" and Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH system_data_types 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+system_data_types \- overview of system data types
+.SH DESCRIPTION
+.\" Layout:
+.\"	A list of type names (the struct/union keyword will be omitted).
+.\"	Each entry will have the following parts:
+.\"		* Include (see NOTES)
+.\"
+.\"		* Definition (no "Definition" header)
+.\"			Only struct/union types will have definition;
+.\"			typedefs will remain opaque.
+.\"
+.\"		* Description (no "Description" header)
+.\"			A few lines describing the type.
+.\"
+.\"		* Versions (optional)
+.\"
+.\"		* Conforming to (see NOTES)
+.\"			Format: CXY and later; POSIX.1-XXXX and later.
+.\"
+.\"		* Notes (optional)
+.\"
+.\"		* Bugs (if any)
+.\"
+.\"		* See also
+.\"------------------------------------- aiocb ------------------------/
+.\"------------------------------------- blkcnt_t ---------------------/
+.\"------------------------------------- blksize_t --------------------/
+.\"------------------------------------- cc_t -------------------------/
+.\"------------------------------------- clock_t ----------------------/
+.\"------------------------------------- clockid_t --------------------/
+.\"------------------------------------- dev_t ------------------------/
+.\"------------------------------------- div_t ------------------------/
+.\"------------------------------------- double_t ---------------------/
+.\"------------------------------------- fd_set -----------------------/
+.\"------------------------------------- fenv_t -----------------------/
+.\"------------------------------------- fexcept_t --------------------/
+.\"------------------------------------- FILE -------------------------/
+.\"------------------------------------- float_t ----------------------/
+.\"------------------------------------- gid_t ------------------------/
+.\"------------------------------------- id_t -------------------------/
+.\"------------------------------------- imaxdiv_t --------------------/
+.\"------------------------------------- intmax_t ---------------------/
+.\"------------------------------------- intN_t -----------------------/
+.\"------------------------------------- intptr_t ---------------------/
+.\"------------------------------------- lconv ------------------------/
+.\"------------------------------------- ldiv_t -----------------------/
+.\"------------------------------------- lldiv_t ----------------------/
+.\"------------------------------------- mode_t -----------------------/
+.\"------------------------------------- off64_t ----------------------/
+.\"------------------------------------- off_t ------------------------/
+.\"------------------------------------- pid_t ------------------------/
+.\"------------------------------------- ptrdiff_t --------------------/
+.\"------------------------------------- regex_t ----------------------/
+.\"------------------------------------- regmatch_t -------------------/
+.\"------------------------------------- regoff_t ---------------------/
+.\"------------------------------------- sigevent ---------------------/
+.\"------------------------------------- siginfo_t --------------------/
+.TP
+.I siginfo_t
+.RS
+.IR Include :
+.IR <signal.h> .
+Alternatively,
+.IR <sys/wait.h> .
+.P
+.EX
+typedef struct {
+    int      si_signo;  /* Signal number */
+    int      si_code;   /* Signal code */
+    pid_t    si_pid;    /* Sending process ID */
+    uid_t    si_uid;    /* Real user ID of sending process */
+    void    *si_addr;   /* Memory location which caused fault */
+    int      si_status; /* Exit value or signal */
+    union sigval si_value;  /* Signal value */
+} siginfo_t;
+.EE
+.P
+Information associated with a signal.
+For further details on this structure
+(including additional, Linux-specific fields), see
+.BR sigaction (2).
+.P
+.IR "Conforming to" :
+POSIX.1-2001 and later.
+.P
+.IR "See also" :
+.BR pidfd_send_signal (2),
+.BR rt_sigqueueinfo (2),
+.BR sigaction (2),
+.BR sigwaitinfo (2),
+.BR psiginfo (3)
+.RE
+.\"------------------------------------- sigset_t ---------------------/
+.TP
+.I sigset_t
+.RS
+.IR Include :
+.IR <signal.h> .
+Alternatively,
+.IR <spawn.h> ,
+or
+.IR <sys/select.h> .
+.P
+This is a type that represents a set of signals.
+According to POSIX, this shall be an integer or structure type.
+.P
+.IR "Conforming to" :
+POSIX.1-2001 and later.
+.P
+.IR "See also" :
+.BR epoll_pwait (2),
+.BR ppoll (2),
+.BR pselect (2),
+.BR sigaction (2),
+.BR signalfd (2),
+.BR sigpending (2),
+.BR sigprocmask (2),
+.BR sigsuspend (2),
+.BR sigwaitinfo (2),
+.BR signal (7)
+.RE
+.\"------------------------------------- sigval -----------------------/
+.\"------------------------------------- size_t -----------------------/
+.\"------------------------------------- sockaddr ---------------------/
+.\"------------------------------------- socklen_t --------------------/
+.\"------------------------------------- ssize_t ----------------------/
+.\"------------------------------------- stat -------------------------/
+.\"------------------------------------- suseconds_t ------------------/
+.\"------------------------------------- time_t -----------------------/
+.\"------------------------------------- timer_t ----------------------/
+.\"------------------------------------- timespec ---------------------/
+.\"------------------------------------- timeval ----------------------/
+.\"------------------------------------- uid_t ----------------------/
+.\"------------------------------------- uintmax_t --------------------/
+.\"------------------------------------- uintN_t ----------------------/
+.\"------------------------------------- uintptr_t --------------------/
+.\"------------------------------------- useconds_t -------------------/
+.\"------------------------------------- va_list ----------------------/
+.\"------------------------------------- void * -----------------------/
+.\"--------------------------------------------------------------------/
+.SH NOTES
+The structures described in this manual page shall contain,
+at least, the members shown in their definition, in no particular order.
+.P
+Most of the integer types described in this page don't have
+a corresponding length modifier for the
+.BR printf (3)
+and the
+.BR scanf (3)
+families of functions.
+To print a value of an integer type that doesn't have a length modifier,
+it should be converted to
+.I intmax_t
+or
+.I uintmax_t
+by an explicit cast.
+To scan into a variable of an integer type
+that doesn't have a length modifier,
+an intermediate temporary variable of type
+.I intmax_t
+or
+.I uintmax_t
+should be used.
+When copying from the temporary variable to the destination variable,
+the value could overflow.
+If the type has upper and lower limits,
+the user should check that the value is within those limits,
+before actually copying the value.
+The example below shows how these conversions should be done.
+.SS Conventions used in this page
+In "Conforming to" we only concern ourselves with
+C99 and later and POSIX.1-2001 and later.
+Some types may be specified in earlier versions of one of these standards,
+but in the interests of simplicity we omit details from earlier standards.
+.P
+In "Include", we first note the "primary" header(s) that
+define the type according to either the C or POSIX.1 standards.
+Under "Alternatively", we note additional headers that
+the standards specify shall define the type.
+.SH EXAMPLES
+The program shown below scans from a string and prints a value stored in
+a variable of an integer type that doesn't have a length modifier.
+The appropriate conversions from and to
+.IR intmax_t ,
+and the appropriate range checks,
+are used as explained in the notes section above.
+.P
+.EX
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+\&
+int
+main (void)
+{
+    static const char *const str = "500000 us in half a second";
+    suseconds_t us;
+    intmax_t    tmp;
+\&
+    /* Scan the number from the string into the temporary variable. */
+\&
+    sscanf(str, "%jd", &tmp);
+\&
+    /* Check that the value is within the valid range of suseconds_t. */
+\&
+    if (tmp < \-1 || tmp > 1000000) {
+        fprintf(stderr, "Scanned value outside valid range!\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Copy the value to the suseconds_t variable \[aq]us\[aq]. */
+\&
+    us = tmp;
+\&
+    /* Even though suseconds_t can hold the value \-1, this isn\[aq]t
+       a sensible number of microseconds. */
+\&
+    if (us < 0) {
+        fprintf(stderr, "Scanned value shouldn\[aq]t be negative!\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Print the value. */
+\&
+    printf("There are %jd microseconds in half a second.\en",
+            (intmax_t) us);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR feature_test_macros (7),
+.BR standards (7)
diff --git a/man/man7/sysvipc.7 b/man/man7/sysvipc.7
new file mode 100644
index 000000000..460ff0f04
--- /dev/null
+++ b/man/man7/sysvipc.7
@@ -0,0 +1,99 @@
+.\" Copyright 2020 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sysvipc 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sysvipc \- System V interprocess communication mechanisms
+.SH DESCRIPTION
+System V IPC is the name given to three interprocess
+communication mechanisms that are widely available on UNIX systems:
+message queues, semaphore, and shared memory.
+.\"
+.SS Message queues
+System V message queues allow data to be exchanged in units called messages.
+Each message can have an associated priority.
+POSIX message queues provide an alternative API for achieving the same result;
+see
+.BR mq_overview (7).
+.P
+The System V message queue API consists of the following system calls:
+.TP
+.BR msgget (2)
+Create a new message queue or obtain the ID of an existing message queue.
+This call returns an identifier that is used in the remaining APIs.
+.TP
+.BR msgsnd (2)
+Add a message to a queue.
+.TP
+.BR msgrcv (2)
+Remove a message from a queue.
+.TP
+.BR msgctl (2)
+Perform various control operations on a queue, including deletion.
+.\"
+.SS Semaphore sets
+System V semaphores allow processes to synchronize their actions.
+System V semaphores are allocated in groups called sets;
+each semaphore in a set is a counting semaphore.
+POSIX semaphores provide an alternative API for achieving the same result;
+see
+.BR sem_overview (7).
+.P
+The System V semaphore API consists of the following system calls:
+.TP
+.BR semget (2)
+Create a new set or obtain the ID of an existing set.
+This call returns an identifier that is used in the remaining APIs.
+.TP
+.BR semop (2)
+Perform operations on the semaphores in a set.
+.TP
+.BR semctl (2)
+Perform various control operations on a set, including deletion.
+.\"
+.SS Shared memory segments
+System V shared memory allows processes to share a region a memory
+(a "segment").
+POSIX shared memory is an alternative API for achieving the same result; see
+.BR shm_overview (7).
+.P
+The System V shared memory API consists of the following system calls:
+.TP
+.BR shmget (2)
+Create a new segment or obtain the ID of an existing segment.
+This call returns an identifier that is used in the remaining APIs.
+.TP
+.BR shmat (2)
+Attach an existing shared memory object into the calling process's
+address space.
+.TP
+.BR shmdt (2)
+Detach a segment from the calling process's address space.
+.TP
+.BR shmctl (2)
+Perform various control operations on a segment, including deletion.
+.\"
+.SS IPC namespaces
+For a discussion of the interaction of System V IPC objects and
+IPC namespaces, see
+.BR ipc_namespaces (7).
+.SH SEE ALSO
+.BR ipcmk (1),
+.BR ipcrm (1),
+.BR ipcs (1),
+.BR lsipc (1),
+.BR ipc (2),
+.BR msgctl (2),
+.BR msgget (2),
+.BR msgrcv (2),
+.BR msgsnd (2),
+.BR semctl (2),
+.BR semget (2),
+.BR semop (2),
+.BR shmat (2),
+.BR shmctl (2),
+.BR shmdt (2),
+.BR shmget (2),
+.BR ftok (3),
+.BR ipc_namespaces (7)
diff --git a/man/man7/tcp.7 b/man/man7/tcp.7
new file mode 100644
index 000000000..c7b393c10
--- /dev/null
+++ b/man/man7/tcp.7
@@ -0,0 +1,1563 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\" and Copyright (C) 2008 Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Note also that many pieces are drawn from the kernel source file
+.\" Documentation/networking/ip-sysctl.txt.
+.\"
+.\" 2.4 Updates by Nivedita Singhvi 4/20/02 <nivedita@us.ibm.com>.
+.\" Modified, 2004-11-11, Michael Kerrisk and Andries Brouwer
+.\"	Updated details of interaction of TCP_CORK and TCP_NODELAY.
+.\"
+.\" 2008-11-21, mtk, many, many updates.
+.\"     The descriptions of /proc files and socket options should now
+.\"     be more or less up to date and complete as at Linux 2.6.27
+.\"     (other than the remaining FIXMEs in the page source below).
+.\"
+.\" FIXME The following need to be documented
+.\"	TCP_MD5SIG (2.6.20)
+.\"	    commit cfb6eeb4c860592edd123fdea908d23c6ad1c7dc
+.\"	    Author was yoshfuji@linux-ipv6.org
+.\"	    Needs CONFIG_TCP_MD5SIG
+.\" From net/inet/Kconfig:
+.\" bool "TCP: MD5 Signature Option support (RFC2385) (EXPERIMENTAL)"
+.\" RFC2385 specifies a method of giving MD5 protection to TCP sessions.
+.\" Its main (only?) use is to protect BGP sessions between core routers
+.\" on the Internet.
+.\"
+.\" There is a TCP_MD5SIG option documented in FreeBSD's tcp(4),
+.\" but probably many details are different on Linux
+.\"	    http://thread.gmane.org/gmane.linux.network/47490
+.\"	    http://www.daemon-systems.org/man/tcp.4.html
+.\"	    http://article.gmane.org/gmane.os.netbsd.devel.network/3767/match=tcp_md5sig+freebsd
+.\"
+.\"	TCP_COOKIE_TRANSACTIONS (2.6.33)
+.\"	    commit 519855c508b9a17878c0977a3cdefc09b59b30df
+.\"	    Author: William Allen Simpson <william.allen.simpson@gmail.com>
+.\"	    commit e56fb50f2b7958b931c8a2fc0966061b3f3c8f3a
+.\"	    Author: William Allen Simpson <william.allen.simpson@gmail.com>
+.\"
+.\"	    REMOVED in Linux 3.10
+.\" 		commit 1a2c6181c4a1922021b4d7df373bba612c3e5f04
+.\"		Author: Christoph Paasch <christoph.paasch@uclouvain.be>
+.\"
+.\"	TCP_THIN_LINEAR_TIMEOUTS (2.6.34)
+.\"	    commit 36e31b0af58728071e8023cf8e20c5166b700717
+.\"	    Author: Andreas Petlund <apetlund@simula.no>
+.\"
+.\"	TCP_THIN_DUPACK (2.6.34)
+.\"	    commit 7e38017557bc0b87434d184f8804cadb102bb903
+.\"	    Author: Andreas Petlund <apetlund@simula.no>
+.\"
+.\"	TCP_REPAIR (3.5)
+.\"	    commit ee9952831cfd0bbe834f4a26489d7dce74582e37
+.\"	    Author: Pavel Emelyanov <xemul@parallels.com>
+.\"	    See also
+.\"		http://criu.org/TCP_connection
+.\"		https://lwn.net/Articles/495304/
+.\"
+.\"	TCP_REPAIR_QUEUE (3.5)
+.\"	    commit ee9952831cfd0bbe834f4a26489d7dce74582e37
+.\"	    Author: Pavel Emelyanov <xemul@parallels.com>
+.\"
+.\"	TCP_QUEUE_SEQ (3.5)
+.\"	    commit ee9952831cfd0bbe834f4a26489d7dce74582e37
+.\"	    Author: Pavel Emelyanov <xemul@parallels.com>
+.\"
+.\"	TCP_REPAIR_OPTIONS (3.5)
+.\"	    commit b139ba4e90dccbf4cd4efb112af96a5c9e0b098c
+.\"	    Author: Pavel Emelyanov <xemul@parallels.com>
+.\"
+.\"     TCP_FASTOPEN (3.6)
+.\"         (Fast Open server side implementation completed in Linux 3.7)
+.\"	    http://lwn.net/Articles/508865/
+.\"
+.\"     TCP_TIMESTAMP (3.9)
+.\"        commit 93be6ce0e91b6a94783e012b1857a347a5e6e9f2
+.\"        Author: Andrey Vagin <avagin@openvz.org>
+.\"
+.\"     TCP_NOTSENT_LOWAT (3.12)
+.\"        commit c9bee3b7fdecb0c1d070c7b54113b3bdfb9a3d36
+.\"        Author: Eric Dumazet <edumazet@google.com>
+.\"
+.\"	TCP_CC_INFO (4.1)
+.\"	   commit 6e9250f59ef9efb932c84850cd221f22c2a03c4a
+.\"	   Author: Eric Dumazet <edumazet@google.com>
+.\"
+.\"	TCP_SAVE_SYN, TCP_SAVED_SYN (4.2)
+.\"	    commit cd8ae85299d54155702a56811b2e035e63064d3d
+.\"	    Author: Eric Dumazet <edumazet@google.com>
+.\"
+.TH tcp 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+tcp \- TCP protocol
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <netinet/in.h>
+.B #include <netinet/tcp.h>
+.P
+.IB tcp_socket " = socket(AF_INET, SOCK_STREAM, 0);"
+.fi
+.SH DESCRIPTION
+This is an implementation of the TCP protocol defined in
+RFC\ 793, RFC\ 1122 and RFC\ 2001 with the NewReno and SACK
+extensions.
+It provides a reliable, stream-oriented,
+full-duplex connection between two sockets on top of
+.BR ip (7),
+for both v4 and v6 versions.
+TCP guarantees that the data arrives in order and
+retransmits lost packets.
+It generates and checks a per-packet checksum to catch
+transmission errors.
+TCP does not preserve record boundaries.
+.P
+A newly created TCP socket has no remote or local address and is not
+fully specified.
+To create an outgoing TCP connection use
+.BR connect (2)
+to establish a connection to another TCP socket.
+To receive new incoming connections, first
+.BR bind (2)
+the socket to a local address and port and then call
+.BR listen (2)
+to put the socket into the listening state.
+After that a new socket for each incoming connection can be accepted using
+.BR accept (2).
+A socket which has had
+.BR accept (2)
+or
+.BR connect (2)
+successfully called on it is fully specified and may transmit data.
+Data cannot be transmitted on listening or not yet connected sockets.
+.P
+Linux supports RFC\ 1323 TCP high performance
+extensions.
+These include Protection Against Wrapped
+Sequence Numbers (PAWS), Window Scaling and Timestamps.
+Window scaling allows the use
+of large (> 64\ kB) TCP windows in order to support links with high
+latency or bandwidth.
+To make use of them, the send and receive buffer sizes must be increased.
+They can be set globally with the
+.I /proc/sys/net/ipv4/tcp_wmem
+and
+.I /proc/sys/net/ipv4/tcp_rmem
+files, or on individual sockets by using the
+.B SO_SNDBUF
+and
+.B SO_RCVBUF
+socket options with the
+.BR setsockopt (2)
+call.
+.P
+The maximum sizes for socket buffers declared via the
+.B SO_SNDBUF
+and
+.B SO_RCVBUF
+mechanisms are limited by the values in the
+.I /proc/sys/net/core/rmem_max
+and
+.I /proc/sys/net/core/wmem_max
+files.
+Note that TCP actually allocates twice the size of
+the buffer requested in the
+.BR setsockopt (2)
+call, and so a succeeding
+.BR getsockopt (2)
+call will not return the same size of buffer as requested in the
+.BR setsockopt (2)
+call.
+TCP uses the extra space for administrative purposes and internal
+kernel structures, and the
+.I /proc
+file values reflect the
+larger sizes compared to the actual TCP windows.
+On individual connections, the socket buffer size must be set prior to the
+.BR listen (2)
+or
+.BR connect (2)
+calls in order to have it take effect.
+See
+.BR socket (7)
+for more information.
+.P
+TCP supports urgent data.
+Urgent data is used to signal the
+receiver that some important message is part of the data
+stream and that it should be processed as soon as possible.
+To send urgent data specify the
+.B MSG_OOB
+option to
+.BR send (2).
+When urgent data is received, the kernel sends a
+.B SIGURG
+signal to the process or process group that has been set as the
+socket "owner" using the
+.B SIOCSPGRP
+or
+.B FIOSETOWN
+ioctls (or the POSIX.1-specified
+.BR fcntl (2)
+.B F_SETOWN
+operation).
+When the
+.B SO_OOBINLINE
+socket option is enabled, urgent data is put into the normal
+data stream (a program can test for its location using the
+.B SIOCATMARK
+ioctl described below),
+otherwise it can be received only when the
+.B MSG_OOB
+flag is set for
+.BR recv (2)
+or
+.BR recvmsg (2).
+.P
+When out-of-band data is present,
+.BR select (2)
+indicates the file descriptor as having an exceptional condition and
+.I poll (2)
+indicates a
+.B POLLPRI
+event.
+.P
+Linux 2.4 introduced a number of changes for improved
+throughput and scaling, as well as enhanced functionality.
+Some of these features include support for zero-copy
+.BR sendfile (2),
+Explicit Congestion Notification, new
+management of TIME_WAIT sockets, keep-alive socket options
+and support for Duplicate SACK extensions.
+.SS Address formats
+TCP is built on top of IP (see
+.BR ip (7)).
+The address formats defined by
+.BR ip (7)
+apply to TCP.
+TCP supports point-to-point communication only;
+broadcasting and multicasting are not
+supported.
+.SS /proc interfaces
+System-wide TCP parameter settings can be accessed by files in the directory
+.IR /proc/sys/net/ipv4/ .
+In addition, most IP
+.I /proc
+interfaces also apply to TCP; see
+.BR ip (7).
+Variables described as
+.I Boolean
+take an integer value, with a nonzero value ("true") meaning that
+the corresponding option is enabled, and a zero value ("false")
+meaning that the option is disabled.
+.TP
+.IR tcp_abc " (Integer; default: 0; Linux 2.6.15 to Linux 3.8)"
+.\" Since Linux 2.6.15; removed in Linux 3.9
+.\" commit ca2eb5679f8ddffff60156af42595df44a315ef0
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+Control the Appropriate Byte Count (ABC), defined in RFC 3465.
+ABC is a way of increasing the congestion window
+.RI ( cwnd )
+more slowly in response to partial acknowledgements.
+Possible values are:
+.RS
+.TP
+.B 0
+increase
+.I cwnd
+once per acknowledgement (no ABC)
+.TP
+.B 1
+increase
+.I cwnd
+once per acknowledgement of full sized segment
+.TP
+.B 2
+allow increase
+.I cwnd
+by two if acknowledgement is
+of two segments to compensate for delayed acknowledgements.
+.RE
+.TP
+.IR tcp_abort_on_overflow " (Boolean; default: disabled; since Linux 2.4)"
+.\" Since Linux 2.3.41
+Enable resetting connections if the listening service is too
+slow and unable to keep up and accept them.
+It means that if overflow occurred due
+to a burst, the connection will recover.
+Enable this option
+.I only
+if you are really sure that the listening daemon
+cannot be tuned to accept connections faster.
+Enabling this option can harm the clients of your server.
+.TP
+.IR tcp_adv_win_scale " (integer; default: 2; since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+Count buffering overhead as
+.IR "bytes/2\[ha]tcp_adv_win_scale" ,
+if
+.I tcp_adv_win_scale
+is greater than 0; or
+.IR "bytes\-bytes/2\[ha](\-tcp_adv_win_scale)" ,
+if
+.I tcp_adv_win_scale
+is less than or equal to zero.
+.IP
+The socket receive buffer space is shared between the
+application and kernel.
+TCP maintains part of the buffer as
+the TCP window, this is the size of the receive window
+advertised to the other end.
+The rest of the space is used
+as the "application" buffer, used to isolate the network
+from scheduling and application latencies.
+The
+.I tcp_adv_win_scale
+default value of 2 implies that the space
+used for the application buffer is one fourth that of the total.
+.TP
+.IR tcp_allowed_congestion_control " (String; default: see text; since Linux 2.4.20)"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+Show/set the congestion control algorithm choices available to unprivileged
+processes (see the description of the
+.B TCP_CONGESTION
+socket option).
+The items in the list are separated by white space and
+terminated by a newline character.
+The list is a subset of those listed in
+.IR tcp_available_congestion_control .
+The default value for this list is "reno" plus the default setting of
+.IR tcp_congestion_control .
+.TP
+.IR tcp_autocorking " (Boolean; default: enabled; since Linux 3.14)"
+.\" commit f54b311142a92ea2e42598e347b84e1655caf8e3
+.\" Text heavily based on Documentation/networking/ip-sysctl.txt
+If this option is enabled, the kernel tries to coalesce small writes
+(from consecutive
+.BR write (2)
+and
+.BR sendmsg (2)
+calls) as much as possible,
+in order to decrease the total number of sent packets.
+Coalescing is done if at least one prior packet for the flow
+is waiting in Qdisc queues or device transmit queue.
+Applications can still use the
+.B TCP_CORK
+socket option to obtain optimal behavior
+when they know how/when to uncork their sockets.
+.TP
+.IR tcp_available_congestion_control " (String; read-only; since Linux 2.4.20)"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+Show a list of the congestion-control algorithms
+that are registered.
+The items in the list are separated by white space and
+terminated by a newline character.
+This list is a limiting set for the list in
+.IR tcp_allowed_congestion_control .
+More congestion-control algorithms may be available as modules,
+but not loaded.
+.TP
+.IR tcp_app_win  " (integer; default: 31; since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+This variable defines how many
+bytes of the TCP window are reserved for buffering overhead.
+.IP
+A maximum of (\fIwindow/2\[ha]tcp_app_win\fP, mss) bytes in the window
+are reserved for the application buffer.
+A value of 0 implies that no amount is reserved.
+.\"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_base_mss " (Integer; default: 512; since Linux 2.6.17)"
+The initial value of
+.I search_low
+to be used by the packetization layer Path MTU discovery (MTU probing).
+If MTU probing is enabled,
+this is the initial MSS used by the connection.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_bic " (Boolean; default: disabled; Linux 2.4.27/2.6.6 to Linux 2.6.13)"
+Enable BIC TCP congestion control algorithm.
+BIC-TCP is a sender-side-only change that ensures a linear RTT
+fairness under large windows while offering both scalability and
+bounded TCP-friendliness.
+The protocol combines two schemes
+called additive increase and binary search increase.
+When the congestion window is large, additive increase with a large
+increment ensures linear RTT fairness as well as good scalability.
+Under small congestion windows, binary search
+increase provides TCP friendliness.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_bic_low_window " (integer; default: 14; Linux 2.4.27/2.6.6 to Linux 2.6.13)"
+Set the threshold window (in packets) where BIC TCP starts to
+adjust the congestion window.
+Below this threshold BIC TCP behaves the same as the default TCP Reno.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_bic_fast_convergence " (Boolean; default: enabled; Linux 2.4.27/2.6.6 to Linux 2.6.13)"
+Force BIC TCP to more quickly respond to changes in congestion window.
+Allows two flows sharing the same connection to converge more rapidly.
+.TP
+.IR tcp_congestion_control " (String; default: see text; since Linux 2.4.13)"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+Set the default congestion-control algorithm to be used for new connections.
+The algorithm "reno" is always available,
+but additional choices may be available depending on kernel configuration.
+The default value for this file is set as part of kernel configuration.
+.TP
+.IR tcp_dma_copybreak " (integer; default: 4096; since Linux 2.6.24)"
+Lower limit, in bytes, of the size of socket reads that will be
+offloaded to a DMA copy engine, if one is present in the system
+and the kernel was configured with the
+.B CONFIG_NET_DMA
+option.
+.TP
+.IR tcp_dsack " (Boolean; default: enabled; since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+Enable RFC\ 2883 TCP Duplicate SACK support.
+.TP
+.IR tcp_fastopen " (Bitmask; default: 0x1; since Linux 3.7)"
+Enables RFC\~7413 Fast Open support.
+The flag is used as a bitmap with the following values:
+.RS
+.TP
+.B 0x1
+Enables client side Fast Open support
+.TP
+.B 0x2
+Enables server side Fast Open support
+.TP
+.B 0x4
+Allows client side to transmit data in SYN without Fast Open option
+.TP
+.B 0x200
+Allows server side to accept SYN data without Fast Open option
+.TP
+.B 0x400
+Enables Fast Open on all listeners without
+.B TCP_FASTOPEN
+socket option
+.RE
+.TP
+.IR tcp_fastopen_key " (since Linux 3.7)"
+Set server side RFC\~7413 Fast Open key to generate Fast Open cookie
+when server side Fast Open support is enabled.
+.TP
+.IR tcp_ecn " (Integer; default: see below; since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+Enable RFC\ 3168 Explicit Congestion Notification.
+.IP
+This file can have one of the following values:
+.RS
+.TP
+.B 0
+Disable ECN.
+Neither initiate nor accept ECN.
+This was the default up to and including Linux 2.6.30.
+.TP
+.B 1
+Enable ECN when requested by incoming connections and also
+request ECN on outgoing connection attempts.
+.TP
+.B 2
+.\" commit 255cac91c3c9ce7dca7713b93ab03c75b7902e0e
+Enable ECN when requested by incoming connections,
+but do not request ECN on outgoing connections.
+This value is supported, and is the default, since Linux 2.6.31.
+.RE
+.IP
+When enabled, connectivity to some destinations could be affected
+due to older, misbehaving middle boxes along the path, causing
+connections to be dropped.
+However, to facilitate and encourage deployment with option 1, and
+to work around such buggy equipment, the
+.B tcp_ecn_fallback
+option has been introduced.
+.TP
+.IR tcp_ecn_fallback " (Boolean; default: enabled; since Linux 4.1)"
+.\" commit 492135557dc090a1abb2cfbe1a412757e3ed68ab
+Enable RFC\ 3168, Section 6.1.1.1. fallback.
+When enabled, outgoing ECN-setup SYNs that time out within the
+normal SYN retransmission timeout will be resent with CWR and
+ECE cleared.
+.TP
+.IR tcp_fack " (Boolean; default: enabled; since Linux 2.2)"
+.\" Since Linux 2.1.92
+Enable TCP Forward Acknowledgement support.
+.TP
+.IR tcp_fin_timeout " (integer; default: 60; since Linux 2.2)"
+.\" Since Linux 2.1.53
+This specifies how many seconds to wait for a final FIN packet before the
+socket is forcibly closed.
+This is strictly a violation of the TCP specification,
+but required to prevent denial-of-service attacks.
+In Linux 2.2, the default value was 180.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_frto " (integer; default: see below; since Linux 2.4.21/2.6)"
+.\" Since Linux 2.4.21/2.5.43
+Enable F-RTO, an enhanced recovery algorithm for TCP retransmission
+timeouts (RTOs).
+It is particularly beneficial in wireless environments
+where packet loss is typically due to random radio interference
+rather than intermediate router congestion.
+See RFC 4138 for more details.
+.IP
+This file can have one of the following values:
+.RS
+.TP
+.B 0
+Disabled.
+This was the default up to and including Linux 2.6.23.
+.TP
+.B 1
+The basic version F-RTO algorithm is enabled.
+.TP
+.B 2
+.\" commit c96fd3d461fa495400df24be3b3b66f0e0b152f9
+Enable SACK-enhanced F-RTO if flow uses SACK.
+The basic version can be used also when
+SACK is in use though in that case scenario(s) exists where F-RTO
+interacts badly with the packet counting of the SACK-enabled TCP flow.
+This value is the default since Linux 2.6.24.
+.RE
+.IP
+Before Linux 2.6.22, this parameter was a Boolean value,
+supporting just values 0 and 1 above.
+.TP
+.IR tcp_frto_response " (integer; default: 0; since Linux 2.6.22)"
+When F-RTO has detected that a TCP retransmission timeout was spurious
+(i.e., the timeout would have been avoided had TCP set a
+longer retransmission timeout),
+TCP has several options concerning what to do next.
+Possible values are:
+.RS
+.TP
+.B 0
+Rate halving based; a smooth and conservative response,
+results in halved congestion window
+.RI ( cwnd )
+and slow-start threshold
+.RI ( ssthresh )
+after one RTT.
+.TP
+.B 1
+Very conservative response; not recommended because even
+though being valid, it interacts poorly with the rest of Linux TCP; halves
+.I cwnd
+and
+.I ssthresh
+immediately.
+.TP
+.B 2
+Aggressive response; undoes congestion-control measures
+that are now known to be unnecessary
+(ignoring the possibility of a lost retransmission that would require
+TCP to be more cautious);
+.I cwnd
+and
+.I ssthresh
+are restored to the values prior to timeout.
+.RE
+.TP
+.IR tcp_keepalive_intvl " (integer; default: 75; since Linux 2.4)"
+.\" Since Linux 2.3.18
+The number of seconds between TCP keep-alive probes.
+.TP
+.IR tcp_keepalive_probes " (integer; default: 9; since Linux 2.2)"
+.\" Since Linux 2.1.43
+The maximum number of TCP keep-alive probes to send
+before giving up and killing the connection if
+no response is obtained from the other end.
+.TP
+.IR tcp_keepalive_time " (integer; default: 7200; since Linux 2.2)"
+.\" Since Linux 2.1.43
+The number of seconds a connection needs to be idle
+before TCP begins sending out keep-alive probes.
+Keep-alives are sent only when the
+.B SO_KEEPALIVE
+socket option is enabled.
+The default value is 7200 seconds (2 hours).
+An idle connection is terminated after
+approximately an additional 11 minutes (9 probes an interval
+of 75 seconds apart) when keep-alive is enabled.
+.IP
+Note that underlying connection tracking mechanisms and
+application timeouts may be much shorter.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_low_latency  " (Boolean; default: disabled; since Linux 2.4.21/2.6; \
+obsolete since Linux 4.14)"
+.\" Since Linux 2.4.21/2.5.60
+If enabled, the TCP stack makes decisions that prefer lower
+latency as opposed to higher throughput.
+It this option is disabled, then higher throughput is preferred.
+An example of an application where this default should be
+changed would be a Beowulf compute cluster.
+Since Linux 4.14,
+.\" commit b6690b14386698ce2c19309abad3f17656bdfaea
+this file still exists, but its value is ignored.
+.TP
+.IR tcp_max_orphans  " (integer; default: see below; since Linux 2.4)"
+.\" Since Linux 2.3.41
+The maximum number of orphaned (not attached to any user file
+handle) TCP sockets allowed in the system.
+When this number is exceeded,
+the orphaned connection is reset and a warning is printed.
+This limit exists only to prevent simple denial-of-service attacks.
+Lowering this limit is not recommended.
+Network conditions might require you to increase the number of
+orphans allowed, but note that each orphan can eat up to \[ti]64\ kB
+of unswappable memory.
+The default initial value is set equal to the kernel parameter NR_FILE.
+This initial default is adjusted depending on the memory in the system.
+.TP
+.IR tcp_max_syn_backlog " (integer; default: see below; since Linux 2.2)"
+.\" Since Linux 2.1.53
+The maximum number of queued connection requests which have
+still not received an acknowledgement from the connecting client.
+If this number is exceeded, the kernel will begin
+dropping requests.
+The default value of 256 is increased to
+1024 when the memory present in the system is adequate or
+greater (>= 128\ MB), and reduced to 128 for those systems with
+very low memory (<= 32\ MB).
+.IP
+Before Linux 2.6.20,
+.\" commit 72a3effaf633bcae9034b7e176bdbd78d64a71db
+it was recommended that if this needed to be increased above 1024,
+the size of the SYNACK hash table
+.RB ( TCP_SYNQ_HSIZE )
+in
+.I include/net/tcp.h
+should be modified to keep
+.IP
+.in +4n
+.EX
+TCP_SYNQ_HSIZE * 16 <= tcp_max_syn_backlog
+.EE
+.in
+.IP
+and the kernel should be
+recompiled.
+In Linux 2.6.20, the fixed sized
+.B TCP_SYNQ_HSIZE
+was removed in favor of dynamic sizing.
+.TP
+.IR tcp_max_tw_buckets " (integer; default: see below; since Linux 2.4)"
+.\" Since Linux 2.3.41
+The maximum number of sockets in TIME_WAIT state allowed in
+the system.
+This limit exists only to prevent simple denial-of-service attacks.
+The default value of NR_FILE*2 is adjusted
+depending on the memory in the system.
+If this number is
+exceeded, the socket is closed and a warning is printed.
+.TP
+.IR tcp_moderate_rcvbuf " (Boolean; default: enabled; since Linux 2.4.17/2.6.7)"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+If enabled, TCP performs receive buffer auto-tuning,
+attempting to automatically size the buffer (no greater than
+.IR tcp_rmem[2] )
+to match the size required by the path for full throughput.
+.TP
+.IR tcp_mem " (since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+This is a vector of 3 integers: [low, pressure, high].
+These bounds, measured in units of the system page size,
+are used by TCP to track its memory usage.
+The defaults are calculated at boot time from the amount of
+available memory.
+(TCP can only use
+.I "low memory"
+for this, which is limited to around 900 megabytes on 32-bit systems.
+64-bit systems do not suffer this limitation.)
+.RS
+.TP
+.I low
+TCP doesn't regulate its memory allocation when the number
+of pages it has allocated globally is below this number.
+.TP
+.I pressure
+When the amount of memory allocated by TCP
+exceeds this number of pages, TCP moderates its memory consumption.
+This memory pressure state is exited
+once the number of pages allocated falls below
+the
+.I low
+mark.
+.TP
+.I high
+The maximum number of pages, globally, that TCP will allocate.
+This value overrides any other limits imposed by the kernel.
+.RE
+.TP
+.IR tcp_mtu_probing " (integer; default: 0; since Linux 2.6.17)"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+This parameter controls TCP Packetization-Layer Path MTU Discovery.
+The following values may be assigned to the file:
+.RS
+.TP
+.B 0
+Disabled
+.TP
+.B 1
+Disabled by default, enabled when an ICMP black hole detected
+.TP
+.B 2
+Always enabled, use initial MSS of
+.IR tcp_base_mss .
+.RE
+.TP
+.IR tcp_no_metrics_save " (Boolean; default: disabled; since Linux 2.6.6)"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+By default, TCP saves various connection metrics in the route cache
+when the connection closes, so that connections established in the
+near future can use these to set initial conditions.
+Usually, this increases overall performance,
+but it may sometimes cause performance degradation.
+If
+.I tcp_no_metrics_save
+is enabled, TCP will not cache metrics on closing connections.
+.TP
+.IR tcp_orphan_retries " (integer; default: 8; since Linux 2.4)"
+.\" Since Linux 2.3.41
+The maximum number of attempts made to probe the other
+end of a connection which has been closed by our end.
+.TP
+.IR tcp_reordering " (integer; default: 3; since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+The maximum a packet can be reordered in a TCP packet stream
+without TCP assuming packet loss and going into slow start.
+It is not advisable to change this number.
+This is a packet reordering detection metric designed to
+minimize unnecessary back off and retransmits provoked by
+reordering of packets on a connection.
+.TP
+.IR tcp_retrans_collapse " (Boolean; default: enabled; since Linux 2.2)"
+.\" Since Linux 2.1.96
+Try to send full-sized packets during retransmit.
+.TP
+.IR tcp_retries1 " (integer; default: 3; since Linux 2.2)"
+.\" Since Linux 2.1.43
+The number of times TCP will attempt to retransmit a
+packet on an established connection normally,
+without the extra effort of getting the network layers involved.
+Once we exceed this number of
+retransmits, we first have the network layer
+update the route if possible before each new retransmit.
+The default is the RFC specified minimum of 3.
+.TP
+.IR tcp_retries2 " (integer; default: 15; since Linux 2.2)"
+.\" Since Linux 2.1.43
+The maximum number of times a TCP packet is retransmitted
+in established state before giving up.
+The default value is 15, which corresponds to a duration of
+approximately between 13 to 30 minutes, depending
+on the retransmission timeout.
+The RFC\ 1122 specified
+minimum limit of 100 seconds is typically deemed too short.
+.TP
+.IR tcp_rfc1337 " (Boolean; default: disabled; since Linux 2.2)"
+.\" Since Linux 2.1.90
+Enable TCP behavior conformant with RFC\ 1337.
+When disabled,
+if a RST is received in TIME_WAIT state, we close
+the socket immediately without waiting for the end
+of the TIME_WAIT period.
+.TP
+.IR tcp_rmem " (since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+This is a vector of 3 integers: [min, default, max].
+These parameters are used by TCP to regulate receive buffer sizes.
+TCP dynamically adjusts the size of the
+receive buffer from the defaults listed below, in the range
+of these values, depending on memory available in the system.
+.RS
+.TP
+.I min
+minimum size of the receive buffer used by each TCP socket.
+The default value is the system page size.
+(On Linux 2.4, the default value is 4\ kB, lowered to
+.B PAGE_SIZE
+bytes in low-memory systems.)
+This value
+is used to ensure that in memory pressure mode,
+allocations below this size will still succeed.
+This is not
+used to bound the size of the receive buffer declared
+using
+.B SO_RCVBUF
+on a socket.
+.TP
+.I default
+the default size of the receive buffer for a TCP socket.
+This value overwrites the initial default buffer size from
+the generic global
+.I net.core.rmem_default
+defined for all protocols.
+The default value is 87380 bytes.
+(On Linux 2.4, this will be lowered to 43689 in low-memory systems.)
+If larger receive buffer sizes are desired, this value should
+be increased (to affect all sockets).
+To employ large TCP windows, the
+.I net.ipv4.tcp_window_scaling
+must be enabled (default).
+.TP
+.I max
+the maximum size of the receive buffer used by each TCP socket.
+This value does not override the global
+.IR net.core.rmem_max .
+This is not used to limit the size of the receive buffer declared using
+.B SO_RCVBUF
+on a socket.
+The default value is calculated using the formula
+.IP
+.in +4n
+.EX
+max(87380, min(4\ MB, \fItcp_mem\fP[1]*PAGE_SIZE/128))
+.EE
+.in
+.IP
+(On Linux 2.4, the default is 87380*2 bytes,
+lowered to 87380 in low-memory systems).
+.RE
+.TP
+.IR tcp_sack " (Boolean; default: enabled; since Linux 2.2)"
+.\" Since Linux 2.1.36
+Enable RFC\ 2018 TCP Selective Acknowledgements.
+.TP
+.IR tcp_slow_start_after_idle " (Boolean; default: enabled; since Linux 2.6.18)"
+.\" The following is from Linux 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+If enabled, provide RFC 2861 behavior and time out the congestion
+window after an idle period.
+An idle period is defined as the current RTO (retransmission timeout).
+If disabled, the congestion window will not
+be timed out after an idle period.
+.TP
+.IR tcp_stdurg " (Boolean; default: disabled; since Linux 2.2)"
+.\" Since Linux 2.1.44
+If this option is enabled, then use the RFC\ 1122 interpretation
+of the TCP urgent-pointer field.
+.\" RFC 793 was ambiguous in its specification of the meaning of the
+.\" urgent pointer.  RFC 1122 (and RFC 961) fixed on a particular
+.\" resolution of this ambiguity (unfortunately the "wrong" one).
+According to this interpretation, the urgent pointer points
+to the last byte of urgent data.
+If this option is disabled, then use the BSD-compatible interpretation of
+the urgent pointer:
+the urgent pointer points to the first byte after the urgent data.
+Enabling this option may lead to interoperability problems.
+.TP
+.IR tcp_syn_retries  " (integer; default: 6; since Linux 2.2)"
+.\" Since Linux 2.1.38
+The maximum number of times initial SYNs for an active TCP
+connection attempt will be retransmitted.
+This value should not be higher than 255.
+The default value is 6, which corresponds to retrying for up to
+approximately 127 seconds.
+Before Linux 3.7,
+.\" commit 6c9ff979d1921e9fd05d89e1383121c2503759b9
+the default value was 5, which
+(in conjunction with calculation based on other kernel parameters)
+corresponded to approximately 180 seconds.
+.TP
+.IR tcp_synack_retries " (integer; default: 5; since Linux 2.2)"
+.\" Since Linux 2.1.38
+The maximum number of times a SYN/ACK segment
+for a passive TCP connection will be retransmitted.
+This number should not be higher than 255.
+.TP
+.IR tcp_syncookies " (integer; default: 1; since Linux 2.2)"
+.\" Since Linux 2.1.43
+Enable TCP syncookies.
+The kernel must be compiled with
+.BR CONFIG_SYN_COOKIES .
+The syncookies feature attempts to protect a
+socket from a SYN flood attack.
+This should be used as a last resort, if at all.
+This is a violation of the TCP protocol,
+and conflicts with other areas of TCP such as TCP extensions.
+It can cause problems for clients and relays.
+It is not recommended as a tuning mechanism for heavily
+loaded servers to help with overloaded or misconfigured conditions.
+For recommended alternatives see
+.IR tcp_max_syn_backlog ,
+.IR tcp_synack_retries ,
+and
+.IR tcp_abort_on_overflow .
+Set to one of the following values:
+.RS
+.TP
+.B 0
+Disable TCP syncookies.
+.TP
+.B 1
+Send out syncookies when the syn backlog queue of a socket overflows.
+.TP
+.B 2
+(since Linux 3.12)
+.\" commit 5ad37d5deee1ff7150a2d0602370101de158ad86
+Send out syncookies unconditionally.
+This can be useful for network testing.
+.RE
+.TP
+.IR tcp_timestamps " (integer; default: 1; since Linux 2.2)"
+.\" Since Linux 2.1.36
+Set to one of the following values to enable or disable RFC\ 1323
+TCP timestamps:
+.RS
+.TP
+.B 0
+Disable timestamps.
+.TP
+.B 1
+Enable timestamps as defined in RFC1323 and use random offset for
+each connection rather than only using the current time.
+.TP
+.B 2
+As for the value 1, but without random offsets.
+.\" commit 25429d7b7dca01dc4f17205de023a30ca09390d0
+Setting
+.I tcp_timestamps
+to this value is meaningful since Linux 4.10.
+.RE
+.TP
+.IR tcp_tso_win_divisor " (integer; default: 3; since Linux 2.6.9)"
+This parameter controls what percentage of the congestion window
+can be consumed by a single TCP Segmentation Offload (TSO) frame.
+The setting of this parameter is a tradeoff between burstiness and
+building larger TSO frames.
+.TP
+.IR tcp_tw_recycle " (Boolean; default: disabled; Linux 2.4 to Linux 4.11)"
+.\" Since Linux 2.3.15
+.\" removed in Linux 4.12; commit 4396e46187ca5070219b81773c4e65088dac50cc
+Enable fast recycling of TIME_WAIT sockets.
+Enabling this option is
+not recommended as the remote IP may not use monotonically increasing
+timestamps (devices behind NAT, devices with per-connection timestamp
+offsets).
+See RFC 1323 (PAWS) and RFC 6191.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_tw_reuse " (Boolean; default: disabled; since Linux 2.4.19/2.6)"
+.\" Since Linux 2.4.19/2.5.43
+Allow to reuse TIME_WAIT sockets for new connections when it is
+safe from protocol viewpoint.
+It should not be changed without advice/request of technical experts.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_vegas_cong_avoid  " (Boolean; default: disabled; Linux 2.2 to Linux 2.6.13)"
+.\" Since Linux 2.1.8; removed in Linux 2.6.13
+Enable TCP Vegas congestion avoidance algorithm.
+TCP Vegas is a sender-side-only change to TCP that anticipates
+the onset of congestion by estimating the bandwidth.
+TCP Vegas adjusts the sending rate by modifying the congestion window.
+TCP Vegas should provide less packet loss, but it is
+not as aggressive as TCP Reno.
+.\"
+.\" The following is from Linux 2.6.12: Documentation/networking/ip-sysctl.txt
+.TP
+.IR tcp_westwood " (Boolean; default: disabled; Linux 2.4.26/2.6.3 to Linux 2.6.13)"
+Enable TCP Westwood+ congestion control algorithm.
+TCP Westwood+ is a sender-side-only modification of the TCP Reno
+protocol stack that optimizes the performance of TCP congestion control.
+It is based on end-to-end bandwidth estimation to set
+congestion window and slow start threshold after a congestion episode.
+Using this estimation, TCP Westwood+ adaptively sets a
+slow start threshold and a congestion window which takes into
+account the bandwidth used at the time congestion is experienced.
+TCP Westwood+ significantly increases fairness with respect to
+TCP Reno in wired networks and throughput over wireless links.
+.TP
+.IR tcp_window_scaling " (Boolean; default: enabled; since Linux 2.2)"
+.\" Since Linux 2.1.36
+Enable RFC\ 1323 TCP window scaling.
+This feature allows the use of a large window
+(> 64\ kB) on a TCP connection, should the other end support it.
+Normally, the 16 bit window length field in the TCP header
+limits the window size to less than 64\ kB.
+If larger windows are desired, applications can increase the size of
+their socket buffers and the window scaling option will be employed.
+If
+.I tcp_window_scaling
+is disabled, TCP will not negotiate the use of window
+scaling with the other end during connection setup.
+.TP
+.IR tcp_wmem " (since Linux 2.4)"
+.\" Since Linux 2.4.0-test7
+This is a vector of 3 integers: [min, default, max].
+These parameters are used by TCP to regulate send buffer sizes.
+TCP dynamically adjusts the size of the send buffer from the
+default values listed below, in the range of these values,
+depending on memory available.
+.RS
+.TP
+.I min
+Minimum size of the send buffer used by each TCP socket.
+The default value is the system page size.
+(On Linux 2.4, the default value is 4\ kB.)
+This value is used to ensure that in memory pressure mode,
+allocations below this size will still succeed.
+This is not used to bound the size of the send buffer declared using
+.B SO_SNDBUF
+on a socket.
+.TP
+.I default
+The default size of the send buffer for a TCP socket.
+This value overwrites the initial default buffer size from
+the generic global
+.I /proc/sys/net/core/wmem_default
+defined for all protocols.
+The default value is 16\ kB.
+.\" True in Linux 2.4 and 2.6
+If larger send buffer sizes are desired, this value
+should be increased (to affect all sockets).
+To employ large TCP windows, the
+.I /proc/sys/net/ipv4/tcp_window_scaling
+must be set to a nonzero value (default).
+.TP
+.I max
+The maximum size of the send buffer used by each TCP socket.
+This value does not override the value in
+.IR /proc/sys/net/core/wmem_max .
+This is not used to limit the size of the send buffer declared using
+.B SO_SNDBUF
+on a socket.
+The default value is calculated using the formula
+.IP
+.in +4n
+.EX
+max(65536, min(4\ MB, \fItcp_mem\fP[1]*PAGE_SIZE/128))
+.EE
+.in
+.IP
+(On Linux 2.4, the default value is 128\ kB,
+lowered 64\ kB depending on low-memory systems.)
+.RE
+.TP
+.IR tcp_workaround_signed_windows " (Boolean; default: disabled; since Linux 2.6.26)"
+If enabled, assume that no receipt of a window-scaling option means that the
+remote TCP is broken and treats the window as a signed quantity.
+If disabled, assume that the remote TCP is not broken even if we do
+not receive a window scaling option from it.
+.SS Socket options
+To set or get a TCP socket option, call
+.BR getsockopt (2)
+to read or
+.BR setsockopt (2)
+to write the option with the option level argument set to
+.BR IPPROTO_TCP .
+Unless otherwise noted,
+.I optval
+is a pointer to an
+.IR int .
+.\" or SOL_TCP on Linux
+In addition,
+most
+.B IPPROTO_IP
+socket options are valid on TCP sockets.
+For more information see
+.BR ip (7).
+.P
+Following is a list of TCP-specific socket options.
+For details of some other socket options that are also applicable
+for TCP sockets, see
+.BR socket (7).
+.TP
+.BR TCP_CONGESTION " (since Linux 2.6.13)"
+.\"	    commit 5f8ef48d240963093451bcf83df89f1a1364f51d
+.\"	    Author: Stephen Hemminger <shemminger@osdl.org>
+The argument for this option is a string.
+This option allows the caller to set the TCP congestion control
+algorithm to be used, on a per-socket basis.
+Unprivileged processes are restricted to choosing one of the algorithms in
+.I tcp_allowed_congestion_control
+(described above).
+Privileged processes
+.RB ( CAP_NET_ADMIN )
+can choose from any of the available congestion-control algorithms
+(see the description of
+.I tcp_available_congestion_control
+above).
+.TP
+.BR TCP_CORK " (since Linux 2.2)"
+.\" precisely: since Linux 2.1.127
+If set, don't send out partial frames.
+All queued partial frames are sent when the option is cleared again.
+This is useful for prepending headers before calling
+.BR sendfile (2),
+or for throughput optimization.
+As currently implemented, there is a 200 millisecond ceiling on the time
+for which output is corked by
+.BR TCP_CORK .
+If this ceiling is reached, then queued data is automatically transmitted.
+This option can be combined with
+.B TCP_NODELAY
+only since Linux 2.5.71.
+This option should not be used in code intended to be portable.
+.TP
+.BR TCP_DEFER_ACCEPT " (since Linux 2.4)"
+.\" Precisely: since Linux 2.3.38
+.\" Useful references:
+.\" http://www.techrepublic.com/article/take-advantage-of-tcp-ip-options-to-optimize-data-transmission/
+.\" http://unix.stackexchange.com/questions/94104/real-world-use-of-tcp-defer-accept
+Allow a listener to be awakened only when data arrives on the socket.
+Takes an integer value (seconds), this can
+bound the maximum number of attempts TCP will make to
+complete the connection.
+This option should not be used in code intended to be portable.
+.TP
+.BR TCP_INFO " (since Linux 2.4)"
+Used to collect information about this socket.
+The kernel returns a \fIstruct tcp_info\fP as defined in the file
+.IR /usr/include/linux/tcp.h .
+This option should not be used in code intended to be portable.
+.TP
+.BR TCP_KEEPCNT " (since Linux 2.4)"
+.\" Precisely: since Linux 2.3.18
+The maximum number of keepalive probes TCP should send
+before dropping the connection.
+This option should not be
+used in code intended to be portable.
+.TP
+.BR TCP_KEEPIDLE " (since Linux 2.4)"
+.\" Precisely: since Linux 2.3.18
+The time (in seconds) the connection needs to remain idle
+before TCP starts sending keepalive probes, if the socket
+option
+.B SO_KEEPALIVE
+has been set on this socket.
+This option should not be used in code intended to be portable.
+.TP
+.BR TCP_KEEPINTVL " (since Linux 2.4)"
+.\" Precisely: since Linux 2.3.18
+The time (in seconds) between individual keepalive probes.
+This option should not be used in code intended to be portable.
+.TP
+.BR TCP_LINGER2 " (since Linux 2.4)"
+.\" Precisely: since Linux 2.3.41
+The lifetime of orphaned FIN_WAIT2 state sockets.
+This option can be used to override the system-wide setting in the file
+.I /proc/sys/net/ipv4/tcp_fin_timeout
+for this socket.
+This is not to be confused with the
+.BR socket (7)
+level option
+.BR SO_LINGER .
+This option should not be used in code intended to be portable.
+.TP
+.B TCP_MAXSEG
+.\" Present in Linux 1.0
+The maximum segment size for outgoing TCP packets.
+In Linux 2.2 and earlier, and in Linux 2.6.28 and later,
+if this option is set before connection establishment, it also
+changes the MSS value announced to the other end in the initial packet.
+Values greater than the (eventual) interface MTU have no effect.
+TCP will also impose
+its minimum and maximum bounds over the value provided.
+.TP
+.B TCP_NODELAY
+.\" Present in Linux 1.0
+If set, disable the Nagle algorithm.
+This means that segments
+are always sent as soon as possible, even if there is only a
+small amount of data.
+When not set, data is buffered until there
+is a sufficient amount to send out, thereby avoiding the
+frequent sending of small packets, which results in poor
+utilization of the network.
+This option is overridden by
+.BR TCP_CORK ;
+however, setting this option forces an explicit flush of
+pending output, even if
+.B TCP_CORK
+is currently set.
+.TP
+.BR TCP_QUICKACK " (since Linux 2.4.4)"
+Enable quickack mode if set or disable quickack
+mode if cleared.
+In quickack mode, acks are sent
+immediately, rather than delayed if needed in accordance
+to normal TCP operation.
+This flag is not permanent,
+it only enables a switch to or from quickack mode.
+Subsequent operation of the TCP protocol will
+once again enter/leave quickack mode depending on
+internal protocol processing and factors such as
+delayed ack timeouts occurring and data transfer.
+This option should not be used in code intended to be
+portable.
+.TP
+.BR TCP_SYNCNT " (since Linux 2.4)"
+.\" Precisely: since Linux 2.3.18
+Set the number of SYN retransmits that TCP should send before
+aborting the attempt to connect.
+It cannot exceed 255.
+This option should not be used in code intended to be portable.
+.TP
+.BR TCP_USER_TIMEOUT " (since Linux 2.6.37)"
+.\"	    commit dca43c75e7e545694a9dd6288553f55c53e2a3a3
+.\"	    Author: Jerry Chu <hkchu@google.com>
+.\" The following text taken nearly verbatim from Jerry Chu's (excellent)
+.\" commit message.
+.\"
+This option takes an
+.I unsigned int
+as an argument.
+When the value is greater than 0,
+it specifies the maximum amount of time in milliseconds that transmitted
+data may remain unacknowledged, or buffered data may remain untransmitted
+(due to zero window size) before TCP will forcibly close the
+corresponding connection and return
+.B ETIMEDOUT
+to the application.
+If the option value is specified as 0,
+TCP will use the system default.
+.IP
+Increasing user timeouts allows a TCP connection to survive extended
+periods without end-to-end connectivity.
+Decreasing user timeouts
+allows applications to "fail fast", if so desired.
+Otherwise, failure may take up to 20 minutes with
+the current system defaults in a normal WAN environment.
+.IP
+This option can be set during any state of a TCP connection,
+but is effective only during the synchronized states of a connection
+(ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, CLOSING, and LAST-ACK).
+Moreover, when used with the TCP keepalive
+.RB ( SO_KEEPALIVE )
+option,
+.B TCP_USER_TIMEOUT
+will override keepalive to determine when to close a
+connection due to keepalive failure.
+.IP
+The option has no effect on when TCP retransmits a packet,
+nor when a keepalive probe is sent.
+.IP
+This option, like many others, will be inherited by the socket returned by
+.BR accept (2),
+if it was set on the listening socket.
+.IP
+Further details on the user timeout feature can be found in
+RFC\ 793 and RFC\ 5482 ("TCP User Timeout Option").
+.TP
+.BR TCP_WINDOW_CLAMP " (since Linux 2.4)"
+.\" Precisely: since Linux 2.3.41
+Bound the size of the advertised window to this value.
+The kernel imposes a minimum size of SOCK_MIN_RCVBUF/2.
+This option should not be used in code intended to be
+portable.
+.TP
+.BR TCP_FASTOPEN " (since Linux 3.6)"
+This option enables Fast Open (RFC\~7413) on the listener socket.
+The value specifies the maximum length of pending SYNs
+(similar to the backlog argument in
+.BR listen (2)).
+Once enabled,
+the listener socket grants the TCP Fast Open cookie
+on incoming SYN with TCP Fast Open option.
+.IP
+More importantly it accepts the data in SYN with a valid Fast Open cookie
+and responds SYN-ACK acknowledging both the data and the SYN sequence.
+.BR accept (2)
+returns a socket that is available for read and write
+when the handshake has not completed yet.
+Thus the data exchange can commence before the handshake completes.
+This option requires enabling the server-side support on sysctl
+.I net.ipv4.tcp_fastopen
+(see above).
+For TCP Fast Open client-side support,
+see
+.BR send (2)
+.B MSG_FASTOPEN
+or
+.B TCP_FASTOPEN_CONNECT
+below.
+.TP
+.BR TCP_FASTOPEN_CONNECT " (since Linux 4.11)"
+This option enables an alternative way to perform Fast Open
+on the active side (client).
+When this option is enabled,
+.BR connect (2)
+would behave differently depending on
+if a Fast Open cookie is available for the destination.
+.IP
+If a cookie is not available (i.e. first contact to the destination),
+.BR connect (2)
+behaves as usual by sending a SYN immediately,
+except the SYN would include an empty Fast Open cookie option
+to solicit a cookie.
+.IP
+If a cookie is available,
+.BR connect (2)
+would return 0 immediately but the SYN transmission is deferred.
+A subsequent
+.BR write (2)
+or
+.BR sendmsg (2)
+would trigger a SYN with data plus cookie in the Fast Open option.
+In other words,
+the actual connect operation is deferred until data is supplied.
+.IP
+.B Note:
+While this option is designed for convenience,
+enabling it does change the behaviors and certain system calls might set
+different
+.I errno
+values.
+With cookie present,
+.BR write (2)
+or
+.BR sendmsg (2)
+must be called right after
+.BR connect (2)
+in order to send out SYN+data to complete 3WHS and establish connection.
+Calling
+.BR read (2)
+right after
+.BR connect (2)
+without
+.BR write (2)
+will cause the blocking socket to be blocked forever.
+.IP
+The application should either set
+.B TCP_FASTOPEN_CONNECT
+socket option before
+.BR write (2)
+or
+.BR sendmsg (2),
+or call
+.BR write (2)
+or
+.BR sendmsg (2)
+with
+.B MSG_FASTOPEN
+flag directly,
+instead of both on the same connection.
+.IP
+Here is the typical call flow with this new option:
+.IP
+.in +4n
+.EX
+s = socket();
+setsockopt(s, IPPROTO_TCP, TCP_FASTOPEN_CONNECT, 1, ...);
+connect(s);
+write(s); /* write() should always follow connect()
+           * in order to trigger SYN to go out. */
+read(s)/write(s);
+/* ... */
+close(s);
+.EE
+.in
+.SS Sockets API
+TCP provides limited support for out-of-band data,
+in the form of (a single byte of) urgent data.
+In Linux this means if the other end sends newer out-of-band
+data the older urgent data is inserted as normal data into
+the stream (even when
+.B SO_OOBINLINE
+is not set).
+This differs from BSD-based stacks.
+.P
+Linux uses the BSD compatible interpretation of the urgent
+pointer field by default.
+This violates RFC\ 1122, but is
+required for interoperability with other stacks.
+It can be changed via
+.IR /proc/sys/net/ipv4/tcp_stdurg .
+.P
+It is possible to peek at out-of-band data using the
+.BR recv (2)
+.B MSG_PEEK
+flag.
+.P
+Since Linux 2.4, Linux supports the use of
+.B MSG_TRUNC
+in the
+.I flags
+argument of
+.BR recv (2)
+(and
+.BR recvmsg (2)).
+This flag causes the received bytes of data to be discarded,
+rather than passed back in a caller-supplied buffer.
+Since Linux 2.4.4,
+.B MSG_TRUNC
+also has this effect when used in conjunction with
+.B MSG_OOB
+to receive out-of-band data.
+.SS Ioctls
+The following
+.BR ioctl (2)
+calls return information in
+.IR value .
+The correct syntax is:
+.P
+.RS
+.nf
+.BI int " value";
+.IB error " = ioctl(" tcp_socket ", " ioctl_type ", &" value ");"
+.fi
+.RE
+.P
+.I ioctl_type
+is one of the following:
+.TP
+.B SIOCINQ
+Returns the amount of queued unread data in the receive buffer.
+The socket must not be in LISTEN state, otherwise an error
+.RB ( EINVAL )
+is returned.
+.B SIOCINQ
+is defined in
+.IR <linux/sockios.h> .
+.\" FIXME https://www.sourceware.org/bugzilla/show_bug.cgi?id=12002,
+.\" filed 2010-09-10, may cause SIOCINQ to be defined in glibc headers
+Alternatively,
+you can use the synonymous
+.BR FIONREAD ,
+defined in
+.IR <sys/ioctl.h> .
+.TP
+.B SIOCATMARK
+Returns true (i.e.,
+.I value
+is nonzero) if the inbound data stream is at the urgent mark.
+.IP
+If the
+.B SO_OOBINLINE
+socket option is set, and
+.B SIOCATMARK
+returns true, then the
+next read from the socket will return the urgent data.
+If the
+.B SO_OOBINLINE
+socket option is not set, and
+.B SIOCATMARK
+returns true, then the
+next read from the socket will return the bytes following
+the urgent data (to actually read the urgent data requires the
+.B recv(MSG_OOB)
+flag).
+.IP
+Note that a read never reads across the urgent mark.
+If an application is informed of the presence of urgent data via
+.BR select (2)
+(using the
+.I exceptfds
+argument) or through delivery of a
+.B SIGURG
+signal,
+then it can advance up to the mark using a loop which repeatedly tests
+.B SIOCATMARK
+and performs a read (requesting any number of bytes) as long as
+.B SIOCATMARK
+returns false.
+.TP
+.B SIOCOUTQ
+Returns the amount of unsent data in the socket send queue.
+The socket must not be in LISTEN state, otherwise an error
+.RB ( EINVAL )
+is returned.
+.B SIOCOUTQ
+is defined in
+.IR <linux/sockios.h> .
+.\" FIXME . https://www.sourceware.org/bugzilla/show_bug.cgi?id=12002,
+.\" filed 2010-09-10, may cause SIOCOUTQ to be defined in glibc headers
+Alternatively,
+you can use the synonymous
+.BR TIOCOUTQ ,
+defined in
+.IR <sys/ioctl.h> .
+.SS Error handling
+When a network error occurs, TCP tries to resend the packet.
+If it doesn't succeed after some time, either
+.B ETIMEDOUT
+or the last received error on this connection is reported.
+.P
+Some applications require a quicker error notification.
+This can be enabled with the
+.B IPPROTO_IP
+level
+.B IP_RECVERR
+socket option.
+When this option is enabled, all incoming
+errors are immediately passed to the user program.
+Use this option with care \[em] it makes TCP less tolerant to routing
+changes and other normal network conditions.
+.SH ERRORS
+.TP
+.B EAFNOTSUPPORT
+Passed socket address type in
+.I sin_family
+was not
+.BR AF_INET .
+.TP
+.B EPIPE
+The other end closed the socket unexpectedly or a read is
+executed on a shut down socket.
+.TP
+.B ETIMEDOUT
+The other end didn't acknowledge retransmitted data after some time.
+.P
+Any errors defined for
+.BR ip (7)
+or the generic socket layer may also be returned for TCP.
+.SH VERSIONS
+Support for Explicit Congestion Notification, zero-copy
+.BR sendfile (2),
+reordering support and some SACK extensions
+(DSACK) were introduced in Linux 2.4.
+Support for forward acknowledgement (FACK), TIME_WAIT recycling,
+and per-connection keepalive socket options were introduced in Linux 2.3.
+.SH BUGS
+Not all errors are documented.
+.P
+IPv6 is not described.
+.\" Only a single Linux kernel version is described
+.\" Info for 2.2 was lost. Should be added again,
+.\" or put into a separate page.
+.\" .SH AUTHORS
+.\" This man page was originally written by Andi Kleen.
+.\" It was updated for 2.4 by Nivedita Singhvi with input from
+.\" Alexey Kuznetsov's Documentation/networking/ip-sysctl.txt
+.\" document.
+.SH SEE ALSO
+.BR accept (2),
+.BR bind (2),
+.BR connect (2),
+.BR getsockopt (2),
+.BR listen (2),
+.BR recvmsg (2),
+.BR sendfile (2),
+.BR sendmsg (2),
+.BR socket (2),
+.BR ip (7),
+.BR socket (7)
+.P
+The kernel source file
+.IR Documentation/networking/ip\-sysctl.txt .
+.P
+RFC\ 793 for the TCP specification.
+.br
+RFC\ 1122 for the TCP requirements and a description of the Nagle algorithm.
+.br
+RFC\ 1323 for TCP timestamp and window scaling options.
+.br
+RFC\ 1337 for a description of TIME_WAIT assassination hazards.
+.br
+RFC\ 3168 for a description of Explicit Congestion Notification.
+.br
+RFC\ 2581 for TCP congestion control algorithms.
+.br
+RFC\ 2018 and RFC\ 2883 for SACK and extensions to SACK.
diff --git a/man/man7/termio.7 b/man/man7/termio.7
new file mode 100644
index 000000000..cc8401aec
--- /dev/null
+++ b/man/man7/termio.7
@@ -0,0 +1,45 @@
+.\" Copyright (c) 2006 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 28 Dec 2006 - Initial Creation
+.\"
+.TH termio 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+termio \- System V terminal driver interface
+.SH DESCRIPTION
+.B termio
+is the name of the old System V terminal driver interface.
+This interface defined a
+.I termio
+structure used to store terminal settings, and a range of
+.BR ioctl (2)
+operations to get and set terminal attributes.
+.P
+The
+.B termio
+interface is now obsolete: POSIX.1-1990 standardized a modified
+version of this interface, under the name
+.BR termios .
+The POSIX.1 data structure differs slightly from the
+System V version, and POSIX.1 defined a suite of functions
+to replace the various
+.BR ioctl (2)
+operations that existed in System V.
+(This was done because
+.BR ioctl (2)
+was unstandardized, and its variadic third argument
+does not allow argument type checking.)
+.P
+If you're looking for a page called "termio", then you can probably
+find most of the information that you seek in either
+.BR termios (3)
+or
+.BR ioctl_tty (2).
+.SH SEE ALSO
+.BR reset (1),
+.BR setterm (1),
+.BR stty (1),
+.BR ioctl_tty (2),
+.BR termios (3),
+.BR tty (4)
diff --git a/man/man7/thread-keyring.7 b/man/man7/thread-keyring.7
new file mode 100644
index 000000000..0a04f9312
--- /dev/null
+++ b/man/man7/thread-keyring.7
@@ -0,0 +1,50 @@
+.\" Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH thread-keyring 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+thread-keyring \- per-thread keyring
+.SH DESCRIPTION
+The thread keyring is a keyring used to anchor keys on behalf of a process.
+It is created only when a thread requests it.
+The thread keyring has the name (description)
+.IR _tid .
+.P
+A special serial number value,
+.BR KEY_SPEC_THREAD_KEYRING ,
+is defined that can be used in lieu of the actual serial number of
+the calling thread's thread keyring.
+.P
+From the
+.BR keyctl (1)
+utility, '\fB@t\fP' can be used instead of a numeric key ID in
+much the same way, but as
+.BR keyctl (1)
+is a program run after forking, this is of no utility.
+.P
+Thread keyrings are not inherited across
+.BR clone (2)
+and
+.BR fork (2)
+and are cleared by
+.BR execve (2).
+A thread keyring is destroyed when the thread that refers to it terminates.
+.P
+Initially, a thread does not have a thread keyring.
+If a thread doesn't have a thread keyring when it is accessed,
+then it will be created if it is to be modified;
+otherwise the operation fails with the error
+.BR ENOKEY .
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR keyctl (3),
+.BR keyrings (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR user\-keyring (7),
+.BR user\-session\-keyring (7)
diff --git a/man/man7/time.7 b/man/man7/time.7
new file mode 100644
index 000000000..a2241ccef
--- /dev/null
+++ b/man/man7/time.7
@@ -0,0 +1,218 @@
+.\" Copyright (c) 2006 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" 2008-06-24, mtk: added some details about where jiffies come into
+.\"     play; added section on high-resolution timers.
+.\"
+.TH time 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+time \- overview of time and timers
+.SH DESCRIPTION
+.SS Real time and process time
+.I "Real time"
+is defined as time measured from some fixed point,
+either from a standard point in the past
+(see the description of the Epoch and calendar time below),
+or from some point (e.g., the start) in the life of a process
+.RI ( "elapsed time" ).
+.P
+.I "Process time"
+is defined as the amount of CPU time used by a process.
+This is sometimes divided into
+.I user
+and
+.I system
+components.
+User CPU time is the time spent executing code in user mode.
+System CPU time is the time spent by the kernel executing
+in system mode on behalf of the process (e.g., executing system calls).
+The
+.BR time (1)
+command can be used to determine the amount of CPU time consumed
+during the execution of a program.
+A program can determine the amount of CPU time it has consumed using
+.BR times (2),
+.BR getrusage (2),
+or
+.BR clock (3).
+.SS The hardware clock
+Most computers have a (battery-powered) hardware clock which the kernel
+reads at boot time in order to initialize the software clock.
+For further details, see
+.BR rtc (4)
+and
+.BR hwclock (8).
+.SS The software clock, HZ, and jiffies
+The accuracy of various system calls that set timeouts,
+(e.g.,
+.BR select (2),
+.BR sigtimedwait (2))
+.\" semtimedop(), mq_timedwait(), io_getevents(), poll() are the same
+.\" futexes and thus sem_timedwait() seem to use high-res timers.
+and measure CPU time (e.g.,
+.BR getrusage (2))
+is limited by the resolution of the
+.IR "software clock" ,
+a clock maintained by the kernel which measures time in
+.IR jiffies .
+The size of a jiffy is determined by the value of the kernel constant
+.IR HZ .
+.P
+The value of
+.I HZ
+varies across kernel versions and hardware platforms.
+On i386 the situation is as follows:
+on kernels up to and including Linux 2.4.x,
+HZ was 100,
+giving a jiffy value of 0.01 seconds;
+starting with Linux 2.6.0,
+HZ was raised to 1000,
+giving a jiffy of 0.001 seconds.
+Since Linux 2.6.13, the HZ value is a kernel
+configuration parameter and can be 100, 250 (the default) or 1000,
+yielding a jiffies value of, respectively, 0.01, 0.004, or 0.001 seconds.
+Since Linux 2.6.20, a further frequency is available:
+300, a number that divides evenly for the common video frame rates
+(PAL, 25 Hz; NTSC, 30 Hz).
+.P
+The
+.BR times (2)
+system call is a special case.
+It reports times with a granularity defined by the kernel constant
+.IR USER_HZ .
+User-space applications can determine the value of this constant using
+.IR sysconf(_SC_CLK_TCK) .
+.\" glibc gets this info with a little help from the ELF loader;
+.\" see glibc elf/dl-support.c and kernel fs/binfmt_elf.c.
+.\"
+.SS System and process clocks; time namespaces
+The kernel supports a range of clocks that measure various kinds of
+elapsed and virtual (i.e., consumed CPU) time.
+These clocks are described in
+.BR clock_gettime (2).
+A few of the clocks are settable using
+.BR clock_settime (2).
+The values of certain clocks are virtualized by time namespaces; see
+.BR time_namespaces (7).
+.\"
+.SS High-resolution timers
+Before Linux 2.6.21, the accuracy of timer and sleep system calls
+(see below) was also limited by the size of the jiffy.
+.P
+Since Linux 2.6.21, Linux supports high-resolution timers (HRTs),
+optionally configurable via
+.BR CONFIG_HIGH_RES_TIMERS .
+On a system that supports HRTs, the accuracy of sleep and timer
+system calls is no longer constrained by the jiffy,
+but instead can be as accurate as the hardware allows
+(microsecond accuracy is typical of modern hardware).
+You can determine whether high-resolution timers are supported by
+checking the resolution returned by a call to
+.BR clock_getres (2)
+or looking at the "resolution" entries in
+.IR /proc/timer_list .
+.P
+HRTs are not supported on all hardware architectures.
+(Support is provided on x86, ARM, and PowerPC, among others.)
+.SS The Epoch
+UNIX systems represent time in seconds since the
+.IR Epoch ,
+1970-01-01 00:00:00 +0000 (UTC).
+.P
+A program can determine the
+.I "calendar time"
+via the
+.BR clock_gettime (2)
+.B CLOCK_REALTIME
+clock,
+which returns time (in seconds and nanoseconds) that have
+elapsed since the Epoch;
+.BR time (2)
+provides similar information, but only with accuracy to the
+nearest second.
+The system time can be changed using
+.BR clock_settime (2).
+.\"
+.SS Broken-down time
+Certain library functions use a structure of
+type
+.I tm
+to represent
+.IR "broken-down time" ,
+which stores time value separated out into distinct components
+(year, month, day, hour, minute, second, etc.).
+This structure is described in
+.BR tm (3type),
+which also describes functions that convert between calendar time and
+broken-down time.
+Functions for converting between broken-down time and printable
+string representations of the time are described in
+.BR ctime (3),
+.BR strftime (3),
+and
+.BR strptime (3).
+.SS Sleeping and setting timers
+Various system calls and functions allow a program to sleep
+(suspend execution) for a specified period of time; see
+.BR nanosleep (2),
+.BR clock_nanosleep (2),
+and
+.BR sleep (3).
+.P
+Various system calls allow a process to set a timer that expires
+at some point in the future, and optionally at repeated intervals;
+see
+.BR alarm (2),
+.BR getitimer (2),
+.BR timerfd_create (2),
+and
+.BR timer_create (2).
+.SS Timer slack
+Since Linux 2.6.28, it is possible to control the "timer slack"
+value for a thread.
+The timer slack is the length of time by
+which the kernel may delay the wake-up of certain
+system calls that block with a timeout.
+Permitting this delay allows the kernel to coalesce wake-up events,
+thus possibly reducing the number of system wake-ups and saving power.
+For more details, see the description of
+.B PR_SET_TIMERSLACK
+in
+.BR prctl (2).
+.SH SEE ALSO
+.ad l
+.nh
+.BR date (1),
+.BR time (1),
+.BR timeout (1),
+.BR adjtimex (2),
+.BR alarm (2),
+.BR clock_gettime (2),
+.BR clock_nanosleep (2),
+.BR getitimer (2),
+.BR getrlimit (2),
+.BR getrusage (2),
+.BR gettimeofday (2),
+.BR nanosleep (2),
+.BR stat (2),
+.BR time (2),
+.BR timer_create (2),
+.BR timerfd_create (2),
+.BR times (2),
+.BR utime (2),
+.BR adjtime (3),
+.BR clock (3),
+.BR clock_getcpuclockid (3),
+.BR ctime (3),
+.BR ntp_adjtime (3),
+.BR ntp_gettime (3),
+.BR pthread_getcpuclockid (3),
+.BR sleep (3),
+.BR strftime (3),
+.BR strptime (3),
+.BR timeradd (3),
+.BR usleep (3),
+.BR rtc (4),
+.BR time_namespaces (7),
+.BR hwclock (8)
diff --git a/man/man7/time_namespaces.7 b/man/man7/time_namespaces.7
new file mode 100644
index 000000000..8a2817be5
--- /dev/null
+++ b/man/man7/time_namespaces.7
@@ -0,0 +1,345 @@
+.\" Copyright (c) 2020 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH time_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+time_namespaces \- overview of Linux time namespaces
+.SH DESCRIPTION
+Time namespaces virtualize the values of two system clocks:
+.IP \[bu] 3
+.B CLOCK_MONOTONIC
+(and likewise
+.B CLOCK_MONOTONIC_COARSE
+and
+.BR CLOCK_MONOTONIC_RAW ),
+a nonsettable clock that represents monotonic time  since\[em]as
+described  by  POSIX\[em]"some  unspecified  point in the past".
+.IP \[bu]
+.B CLOCK_BOOTTIME
+(and likewise
+.BR CLOCK_BOOTTIME_ALARM ),
+a nonsettable clock that is identical to
+.BR CLOCK_MONOTONIC ,
+except that it also includes any time that the system is suspended.
+.P
+Thus, the processes in a time namespace share per-namespace values
+for these clocks.
+This affects various APIs that measure against these clocks, including:
+.BR clock_gettime (2),
+.BR clock_nanosleep (2),
+.BR nanosleep (2),
+.BR timer_settime (2),
+.BR timerfd_settime (2),
+and
+.IR /proc/uptime .
+.P
+Currently, the only way to create a time namespace is by calling
+.BR unshare (2)
+with the
+.B CLONE_NEWTIME
+flag.
+This call creates a new time namespace but does
+.I not
+place the calling process in the new namespace.
+Instead, the calling process's
+subsequently created children are placed in the new namespace.
+This allows clock offsets (see below) for the new namespace
+to be set before the first process is placed in the namespace.
+The
+.IR /proc/ pid /ns/time_for_children
+symbolic link shows the time namespace in which
+the children of a process will be created.
+(A process can use a file descriptor opened on
+this symbolic link in a call to
+.BR setns (2)
+in order to move into the namespace.)
+.\"
+.SS \fI/proc/\fPpid\fI/timens_offsets\fP
+Associated with each time namespace are offsets,
+expressed with respect to the initial time namespace,
+that define the values of the monotonic and
+boot-time clocks in that namespace.
+These offsets are exposed via the file
+.IR /proc/ pid /timens_offsets .
+Within this file,
+the offsets are expressed as lines consisting of
+three space-delimited fields:
+.P
+.in +4n
+.EX
+<clock-id> <offset-secs> <offset-nanosecs>
+.EE
+.in
+.P
+The
+.I clock-id
+is a string that identifies the clock whose offsets are being shown.
+This field is either
+.IR monotonic ,
+for
+.BR CLOCK_MONOTONIC ,
+or
+.IR boottime ,
+for
+.BR CLOCK_BOOTTIME .
+The remaining fields express the offset (seconds plus nanoseconds) for the
+clock in this time namespace.
+These offsets are expressed relative to the clock values in
+the initial time namespace.
+The
+.I offset-secs
+value can be negative, subject to restrictions noted below;
+.I offset-nanosecs
+is an unsigned value.
+.P
+In the initial time namespace, the contents of the
+.I timens_offsets
+file are as follows:
+.P
+.in +4n
+.EX
+$ \fBcat /proc/self/timens_offsets\fP
+monotonic           0         0
+boottime            0         0
+.EE
+.in
+.P
+In a new time namespace that has had no member processes,
+the clock offsets can be modified by writing newline-terminated
+records of the same form to the
+.I timens_offsets
+file.
+The file can be written to multiple times,
+but after the first process has been created in or has entered the namespace,
+.BR write (2)s
+on this file fail with the error
+.BR EACCES .
+In order to write to the
+.I timens_offsets
+file, a process must have the
+.B CAP_SYS_TIME
+capability in the user namespace that owns the time namespace.
+.P
+Writes to the
+.I timens_offsets
+file can fail with the following errors:
+.TP
+.B EINVAL
+An
+.I offset-nanosecs
+value is greater than 999,999,999.
+.TP
+.B EINVAL
+A
+.I clock-id
+value is not valid.
+.TP
+.B EPERM
+The caller does not have the
+.B CAP_SYS_TIME
+capability.
+.TP
+.B ERANGE
+An
+.I offset-secs
+value is out of range.
+In particular;
+.RS
+.IP \[bu] 3
+.I offset-secs
+can't be set to a value which would make the current
+time on the corresponding clock inside the namespace a negative value; and
+.IP \[bu]
+.I offset-secs
+can't be set to a value such that the time on the corresponding clock
+inside the namespace would exceed half of the value of the kernel constant
+.B KTIME_SEC_MAX
+(this limits the clock value to a maximum of approximately 146 years).
+.RE
+.P
+In a new time namespace created by
+.BR unshare (2),
+the contents of the
+.I timens_offsets
+file are inherited from the time namespace of the creating process.
+.SH NOTES
+Use of time namespaces requires a kernel that is configured with the
+.B CONFIG_TIME_NS
+option.
+.P
+Note that time namespaces do not virtualize the
+.B CLOCK_REALTIME
+clock.
+Virtualization of this clock was avoided for reasons of complexity
+and overhead within the kernel.
+.P
+For compatibility with the initial implementation, when writing a
+.I clock-id
+to the
+.IR /proc/ pid /timens_offsets
+file, the numerical values of the IDs can be written
+instead of the symbolic names show above; i.e., 1 instead of
+.IR monotonic ,
+and 7 instead of
+.IR boottime .
+For readability, the use of the symbolic names over the numbers is preferred.
+.P
+The motivation for adding time namespaces was to allow
+the monotonic and boot-time clocks to maintain consistent values
+during container migration and checkpoint/restore.
+.SH EXAMPLES
+The following shell session demonstrates the operation of time namespaces.
+We begin by displaying the inode number of the time namespace
+of a shell in the initial time namespace:
+.P
+.in +4n
+.EX
+$ \fBreadlink /proc/$$/ns/time\fP
+time:[4026531834]
+.EE
+.in
+.P
+Continuing in the initial time namespace, we display the system uptime using
+.BR uptime (1)
+and use the
+.I clock_times
+example program shown in
+.BR clock_getres (2)
+to display the values of various clocks:
+.P
+.in +4n
+.EX
+$ \fBuptime \-\-pretty\fP
+up 21 hours, 17 minutes
+$ \fB./clock_times\fP
+CLOCK_REALTIME : 1585989401.971 (18356 days +  8h 36m 41s)
+CLOCK_TAI      : 1585989438.972 (18356 days +  8h 37m 18s)
+CLOCK_MONOTONIC:      56338.247 (15h 38m 58s)
+CLOCK_BOOTTIME :      76633.544 (21h 17m 13s)
+.EE
+.in
+.P
+We then use
+.BR unshare (1)
+to create a time namespace and execute a
+.BR bash (1)
+shell.
+From the new shell, we use the built-in
+.B echo
+command to write records to the
+.I timens_offsets
+file adjusting the offset for the
+.B CLOCK_MONOTONIC
+clock forward 2 days
+and the offset for the
+.B CLOCK_BOOTTIME
+clock forward 7 days:
+.P
+.in +4n
+.EX
+$ \fBPS1="ns2# " sudo unshare \-T \-\- bash \-\-norc\fP
+ns2# \fBecho "monotonic $((2*24*60*60)) 0" > /proc/$$/timens_offsets\fP
+ns2# \fBecho "boottime  $((7*24*60*60)) 0" > /proc/$$/timens_offsets\fP
+.EE
+.in
+.P
+Above, we started the
+.BR bash (1)
+shell with the
+.B \-\-norc
+option so that no start-up scripts were executed.
+This ensures that no child processes are created from the
+shell before we have a chance to update the
+.I timens_offsets
+file.
+.P
+We then use
+.BR cat (1)
+to display the contents of the
+.I timens_offsets
+file.
+The execution of
+.BR cat (1)
+creates the first process in the new time namespace,
+after which further attempts to update the
+.I timens_offsets
+file produce an error.
+.P
+.in +4n
+.EX
+ns2# \fBcat /proc/$$/timens_offsets\fP
+monotonic      172800         0
+boottime       604800         0
+ns2# \fBecho "boottime $((9*24*60*60)) 0" > /proc/$$/timens_offsets\fP
+bash: echo: write error: Permission denied
+.EE
+.in
+.P
+Continuing in the new namespace, we execute
+.BR uptime (1)
+and the
+.I clock_times
+example program:
+.P
+.in +4n
+.EX
+ns2# \fBuptime \-\-pretty\fP
+up 1 week, 21 hours, 18 minutes
+ns2# \fB./clock_times\fP
+CLOCK_REALTIME : 1585989457.056 (18356 days +  8h 37m 37s)
+CLOCK_TAI      : 1585989494.057 (18356 days +  8h 38m 14s)
+CLOCK_MONOTONIC:     229193.332 (2 days + 15h 39m 53s)
+CLOCK_BOOTTIME :     681488.629 (7 days + 21h 18m  8s)
+.EE
+.in
+.P
+From the above output, we can see that the monotonic
+and boot-time clocks have different values in the new time namespace.
+.P
+Examining the
+.IR /proc/ pid /ns/time
+and
+.IR /proc/ pid /ns/time_for_children
+symbolic links, we see that the shell is a member of the initial time
+namespace, but its children are created in the new namespace.
+.P
+.in +4n
+.EX
+ns2# \fBreadlink /proc/$$/ns/time\fP
+time:[4026531834]
+ns2# \fBreadlink /proc/$$/ns/time_for_children\fP
+time:[4026532900]
+ns2# \fBreadlink /proc/self/ns/time\fP   # Creates a child process
+time:[4026532900]
+.EE
+.in
+.P
+Returning to the shell in the initial time namespace,
+we see that the monotonic and boot-time clocks
+are unaffected by the
+.I timens_offsets
+changes that were made in the other time namespace:
+.P
+.in +4n
+.EX
+$ \fBuptime \-\-pretty\fP
+up 21 hours, 19 minutes
+$ \fB./clock_times\fP
+CLOCK_REALTIME : 1585989401.971 (18356 days +  8h 38m 51s)
+CLOCK_TAI      : 1585989438.972 (18356 days +  8h 39m 28s)
+CLOCK_MONOTONIC:      56338.247 (15h 41m  8s)
+CLOCK_BOOTTIME :      76633.544 (21h 19m 23s)
+.EE
+.in
+.SH SEE ALSO
+.BR nsenter (1),
+.BR unshare (1),
+.BR clock_settime (2),
+.\" clone3() support for time namespaces is a work in progress
+.\" .BR clone3 (2),
+.BR setns (2),
+.BR unshare (2),
+.BR namespaces (7),
+.BR time (7)
diff --git a/man/man7/tis-620.7 b/man/man7/tis-620.7
new file mode 100644
index 000000000..cbd4cfe7c
--- /dev/null
+++ b/man/man7/tis-620.7
@@ -0,0 +1 @@
+.so man7/iso_8859-11.7
diff --git a/man/man7/udp.7 b/man/man7/udp.7
new file mode 100644
index 000000000..5827102b4
--- /dev/null
+++ b/man/man7/udp.7
@@ -0,0 +1,312 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" $Id: udp.7,v 1.7 2000/01/22 01:55:05 freitag Exp $
+.\"
+.TH udp 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+udp \- User Datagram Protocol for IPv4
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <netinet/in.h>
+.B #include <netinet/udp.h>
+.P
+.IB udp_socket " = socket(AF_INET, SOCK_DGRAM, 0);"
+.fi
+.SH DESCRIPTION
+This is an implementation of the User Datagram Protocol
+described in RFC\ 768.
+It implements a connectionless, unreliable datagram packet service.
+Packets may be reordered or duplicated before they arrive.
+UDP generates and checks checksums to catch transmission errors.
+.P
+When a UDP socket is created,
+its local and remote addresses are unspecified.
+Datagrams can be sent immediately using
+.BR sendto (2)
+or
+.BR sendmsg (2)
+with a valid destination address as an argument.
+When
+.BR connect (2)
+is called on the socket, the default destination address is set and
+datagrams can now be sent using
+.BR send (2)
+or
+.BR write (2)
+without specifying a destination address.
+It is still possible to send to other destinations by passing an
+address to
+.BR sendto (2)
+or
+.BR sendmsg (2).
+In order to receive packets, the socket can be bound to a local
+address first by using
+.BR bind (2).
+Otherwise, the socket layer will automatically assign
+a free local port out of the range defined by
+.I /proc/sys/net/ipv4/ip_local_port_range
+and bind the socket to
+.BR INADDR_ANY .
+.P
+All receive operations return only one packet.
+When the packet is smaller than the passed buffer, only that much
+data is returned; when it is bigger, the packet is truncated and the
+.B MSG_TRUNC
+flag is set.
+.B MSG_WAITALL
+is not supported.
+.P
+IP options may be sent or received using the socket options described in
+.BR ip (7).
+They are processed by the kernel only when the appropriate
+.I /proc
+parameter
+is enabled (but still passed to the user even when it is turned off).
+See
+.BR ip (7).
+.P
+When the
+.B MSG_DONTROUTE
+flag is set on sending, the destination address must refer to a local
+interface address and the packet is sent only to that interface.
+.P
+By default, Linux UDP does path MTU (Maximum Transmission Unit) discovery.
+This means the kernel
+will keep track of the MTU to a specific target IP address and return
+.B EMSGSIZE
+when a UDP packet write exceeds it.
+When this happens, the application should decrease the packet size.
+Path MTU discovery can be also turned off using the
+.B IP_MTU_DISCOVER
+socket option or the
+.I /proc/sys/net/ipv4/ip_no_pmtu_disc
+file; see
+.BR ip (7)
+for details.
+When turned off, UDP will fragment outgoing UDP packets
+that exceed the interface MTU.
+However, disabling it is not recommended
+for performance and reliability reasons.
+.SS Address format
+UDP uses the IPv4
+.I sockaddr_in
+address format described in
+.BR ip (7).
+.SS Error handling
+All fatal errors will be passed to the user as an error return even
+when the socket is not connected.
+This includes asynchronous errors
+received from the network.
+You may get an error for an earlier packet
+that was sent on the same socket.
+This behavior differs from many other BSD socket implementations
+which don't pass any errors unless the socket is connected.
+Linux's behavior is mandated by
+.BR RFC\ 1122 .
+.P
+For compatibility with legacy code, in Linux 2.0 and 2.2
+it was possible to set the
+.B SO_BSDCOMPAT
+.B SOL_SOCKET
+option to receive remote errors only when the socket has been
+connected (except for
+.B EPROTO
+and
+.BR EMSGSIZE ).
+Locally generated errors are always passed.
+Support for this socket option was removed in later kernels; see
+.BR socket (7)
+for further information.
+.P
+When the
+.B IP_RECVERR
+option is enabled, all errors are stored in the socket error queue,
+and can be received by
+.BR recvmsg (2)
+with the
+.B MSG_ERRQUEUE
+flag set.
+.SS /proc interfaces
+System-wide UDP parameter settings can be accessed by files in the directory
+.IR /proc/sys/net/ipv4/ .
+.TP
+.IR udp_mem " (since Linux 2.6.25)"
+This is a vector of three integers governing the number
+of pages allowed for queueing by all UDP sockets.
+.RS
+.TP
+.I min
+Below this number of pages, UDP is not bothered about its
+memory appetite.
+When the amount of memory allocated by UDP exceeds
+this number, UDP starts to moderate memory usage.
+.TP
+.I pressure
+This value was introduced to follow the format of
+.I tcp_mem
+(see
+.BR tcp (7)).
+.TP
+.I max
+Number of pages allowed for queueing by all UDP sockets.
+.RE
+.IP
+Defaults values for these three items are
+calculated at boot time from the amount of available memory.
+.TP
+.IR udp_rmem_min " (integer; default value: PAGE_SIZE; since Linux 2.6.25)"
+Minimal size, in bytes, of receive buffers used by UDP sockets in moderation.
+Each UDP socket is able to use the size for receiving data,
+even if total pages of UDP sockets exceed
+.I udp_mem
+pressure.
+.TP
+.IR udp_wmem_min " (integer; default value: PAGE_SIZE; since Linux 2.6.25)"
+Minimal size, in bytes, of send buffer used by UDP sockets in moderation.
+Each UDP socket is able to use the size for sending data,
+even if total pages of UDP sockets exceed
+.I udp_mem
+pressure.
+.SS Socket options
+To set or get a UDP socket option, call
+.BR getsockopt (2)
+to read or
+.BR setsockopt (2)
+to write the option with the option level argument set to
+.BR IPPROTO_UDP .
+Unless otherwise noted,
+.I optval
+is a pointer to an
+.IR int .
+.P
+Following is a list of UDP-specific socket options.
+For details of some other socket options that are also applicable
+for UDP sockets, see
+.BR socket (7).
+.TP
+.BR UDP_CORK " (since Linux 2.5.44)"
+If this option is enabled, then all data output on this socket
+is accumulated into a single datagram that is transmitted when
+the option is disabled.
+This option should not be used in code intended to be
+portable.
+.\" FIXME document UDP_ENCAP (new in Linux 2.5.67)
+.\" From include/linux/udp.h:
+.\"     UDP_ENCAP_ESPINUDP_NON_IKE draft-ietf-ipsec-nat-t-ike-00/01
+.\"     UDP_ENCAP_ESPINUDP draft-ietf-ipsec-udp-encaps-06
+.\"     UDP_ENCAP_L2TPINUDP rfc2661
+.\" FIXME Document UDP_NO_CHECK6_TX and UDP_NO_CHECK6_RX, added in Linux 3.16
+.TP
+.BR UDP_SEGMENT " (since Linux 4.18)"
+Enables UDP segmentation offload.
+Segmentation offload reduces
+.BR send (2)
+cost by transferring multiple datagrams worth of data
+as a single large packet through the kernel transmit path,
+even when that exceeds MTU.
+As late as possible,
+the large packet is split by segment size into a series of datagrams.
+This segmentation offload step is deferred to hardware if supported,
+else performed in software.
+This option takes a value in the range
+.RB [ 0 ,\~ USHRT_MAX ]
+that sets the segment size:
+the size of datagram payload,
+excluding the UDP header.
+The segment size must be chosen such that
+at most 64 datagrams are sent in a single call
+and that the datagrams after segmentation meet
+the same MTU rules that apply to datagrams sent without this option.
+Segmentation offload depends on checksum offload,
+as datagram checksums are computed after segmentation.
+The option may also be set for individual
+.BR sendmsg (2)
+calls by passing it as a
+.BR cmsg (3).
+A value of zero disables the feature.
+This option should not be used in code intended to be portable.
+.TP
+.BR UDP_GRO " (since Linux 5.0)"
+Enables UDP receive offload.
+If enabled,
+the socket may receive multiple datagrams worth of data
+as a single large buffer,
+together with a
+.BR cmsg (3)
+that holds the segment size.
+This option is the inverse of segmentation offload.
+It reduces receive cost by handling multiple datagrams worth of data
+as a single large packet in the kernel receive path,
+even when that exceeds MTU.
+This option should not be used in code intended to be portable.
+.SS Ioctls
+These ioctls can be accessed using
+.BR ioctl (2).
+The correct syntax is:
+.P
+.RS
+.nf
+.BI int " value";
+.IB error " = ioctl(" udp_socket ", " ioctl_type ", &" value ");"
+.fi
+.RE
+.TP
+.BR FIONREAD " (" SIOCINQ )
+Gets a pointer to an integer as argument.
+Returns the size of the next pending datagram in the integer in bytes,
+or 0 when no datagram is pending.
+.B Warning:
+Using
+.BR FIONREAD ,
+it is impossible to distinguish the case where no datagram is pending
+from the case where the next pending datagram contains zero bytes of data.
+It is safer to use
+.BR select (2),
+.BR poll (2),
+or
+.BR epoll (7)
+to distinguish these cases.
+.\" See http://www.securiteam.com/unixfocus/5KP0I15IKO.html
+.\" "GNUnet DoS (UDP Socket Unreachable)", 14 May 2006
+.TP
+.BR TIOCOUTQ " (" SIOCOUTQ )
+Returns the number of data bytes in the local send queue.
+Supported only with Linux 2.4 and above.
+.P
+In addition, all ioctls documented in
+.BR ip (7)
+and
+.BR socket (7)
+are supported.
+.SH ERRORS
+All errors documented for
+.BR socket (7)
+or
+.BR ip (7)
+may be returned by a send or receive on a UDP socket.
+.TP
+.B ECONNREFUSED
+No receiver was associated with the destination address.
+This might be caused by a previous packet sent over the socket.
+.SH VERSIONS
+.B IP_RECVERR
+is a new feature in Linux 2.2.
+.\" .SH CREDITS
+.\" This man page was written by Andi Kleen.
+.SH SEE ALSO
+.BR ip (7),
+.BR raw (7),
+.BR socket (7),
+.BR udplite (7)
+.P
+The kernel source file
+.IR Documentation/networking/ip\-sysctl.txt .
+.P
+RFC\ 768 for the User Datagram Protocol.
+.br
+RFC\ 1122 for the host requirements.
+.br
+RFC\ 1191 for a description of path MTU discovery.
diff --git a/man/man7/udplite.7 b/man/man7/udplite.7
new file mode 100644
index 000000000..4ad6047ea
--- /dev/null
+++ b/man/man7/udplite.7
@@ -0,0 +1,137 @@
+.\" Copyright (c) 2008 by Gerrit Renker <gerrit@erg.abdn.ac.uk>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" $Id: udplite.7,v 1.12 2008/07/23 15:22:22 gerrit Exp gerrit $
+.\"
+.TH udplite 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+udplite \- Lightweight User Datagram Protocol
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.\" FIXME . see #defines under `BUGS',
+.\"        when glibc supports this, add
+.\"        #include <netinet/udplite.h>
+.P
+.B sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);
+.fi
+.SH DESCRIPTION
+This is an implementation of the Lightweight User Datagram Protocol
+(UDP-Lite), as described in RFC\ 3828.
+.P
+UDP-Lite is an extension of UDP (RFC\ 768) to support variable-length
+checksums.
+This has advantages for some types of multimedia transport that
+may be able to make use of slightly damaged datagrams,
+rather than having them discarded by lower-layer protocols.
+.P
+The variable-length checksum coverage is set via a
+.BR setsockopt (2)
+option.
+If this option is not set, the only difference from UDP is
+in using a different IP protocol identifier (IANA number 136).
+.P
+The UDP-Lite implementation is a full extension of
+.BR udp (7)\[em]that
+is, it shares the same API and API behavior, and in addition
+offers two socket options to control the checksum coverage.
+.SS Address format
+UDP-Litev4 uses the
+.I sockaddr_in
+address format described in
+.BR ip (7).
+UDP-Litev6 uses the
+.I sockaddr_in6
+address format described in
+.BR ipv6 (7).
+.SS Socket options
+To set or get a UDP-Lite socket option, call
+.BR getsockopt (2)
+to read or
+.BR setsockopt (2)
+to write the option with the option level argument set to
+.BR IPPROTO_UDPLITE .
+In addition, all
+.B IPPROTO_UDP
+socket options are valid on a UDP-Lite socket.
+See
+.BR udp (7)
+for more information.
+.P
+The following two options are specific to UDP-Lite.
+.TP
+.B UDPLITE_SEND_CSCOV
+This option sets the sender checksum coverage and takes an
+.I int
+as argument, with a checksum coverage value in the range 0..2\[ha]16-1.
+.IP
+A value of 0 means that the entire datagram is always covered.
+Values from 1\-7 are illegal (RFC\ 3828, 3.1) and are rounded up to
+the minimum coverage of 8.
+.IP
+With regard to IPv6 jumbograms (RFC\ 2675), the UDP-Litev6 checksum
+coverage is limited to the first 2\[ha]16-1 octets, as per RFC\ 3828, 3.5.
+Higher values are therefore silently truncated to 2\[ha]16-1.
+If in doubt, the current coverage value can always be queried using
+.BR getsockopt (2).
+.TP
+.B UDPLITE_RECV_CSCOV
+This is the receiver-side analogue and uses the same argument format
+and value range as
+.BR UDPLITE_SEND_CSCOV .
+This option is not required to enable traffic with partial checksum
+coverage.
+Its function is that of a traffic filter: when enabled, it
+instructs the kernel to drop all packets which have a coverage
+.I less
+than the specified coverage value.
+.IP
+When the value of
+.B UDPLITE_RECV_CSCOV
+exceeds the actual packet coverage, incoming packets are silently dropped,
+but may generate a warning message in the system log.
+.\" SO_NO_CHECK exists and is supported by UDPv4, but is
+.\" commented out in socket(7), hence also commented out here
+.\".P
+.\"Since UDP-Lite mandates checksums, checksumming can not be disabled
+.\"via the
+.\".B SO_NO_CHECK
+.\"option from
+.\".BR socket (7).
+.SH ERRORS
+All errors documented for
+.BR udp (7)
+may be returned.
+UDP-Lite does not add further errors.
+.SH FILES
+.TP
+.I /proc/net/snmp
+Basic UDP-Litev4 statistics counters.
+.TP
+.I /proc/net/snmp6
+Basic UDP-Litev6 statistics counters.
+.SH VERSIONS
+UDP-Litev4/v6 first appeared in Linux 2.6.20.
+.SH BUGS
+.\" FIXME . remove this section once glibc supports UDP-Lite
+Where glibc support is missing, the following definitions are needed:
+.P
+.in +4n
+.EX
+#define IPPROTO_UDPLITE     136
+.\" The following two are defined in the kernel in linux/net/udplite.h
+#define UDPLITE_SEND_CSCOV  10
+#define UDPLITE_RECV_CSCOV  11
+.EE
+.in
+.SH SEE ALSO
+.BR ip (7),
+.BR ipv6 (7),
+.BR socket (7),
+.BR udp (7)
+.P
+RFC\ 3828 for the Lightweight User Datagram Protocol (UDP-Lite).
+.P
+.I Documentation/networking/udplite.txt
+in the Linux kernel source tree
diff --git a/man/man7/unicode.7 b/man/man7/unicode.7
new file mode 100644
index 000000000..6bdf0bad8
--- /dev/null
+++ b/man/man7/unicode.7
@@ -0,0 +1,246 @@
+.\" Copyright (C) Markus Kuhn, 1995, 2001
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1995-11-26  Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"      First version written
+.\" 2001-05-11  Markus Kuhn <mgk25@cl.cam.ac.uk>
+.\"      Update
+.\"
+.TH unicode 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+unicode \- universal character set
+.SH DESCRIPTION
+The international standard ISO/IEC 10646 defines the
+Universal Character Set (UCS).
+UCS contains all characters of all other character set standards.
+It also guarantees "round-trip compatibility";
+in other words,
+conversion tables can be built such that no information is lost
+when a string is converted from any other encoding to UCS and back.
+.P
+UCS contains the characters required to represent practically all
+known languages.
+This includes not only the Latin, Greek, Cyrillic,
+Hebrew, Arabic, Armenian, and Georgian scripts, but also Chinese,
+Japanese and Korean Han ideographs as well as scripts such as
+Hiragana, Katakana, Hangul, Devanagari, Bengali, Gurmukhi, Gujarati,
+Oriya, Tamil, Telugu, Kannada, Malayalam, Thai, Lao, Khmer, Bopomofo,
+Tibetan, Runic, Ethiopic, Canadian Syllabics, Cherokee, Mongolian,
+Ogham, Myanmar, Sinhala, Thaana, Yi, and others.
+For scripts not yet
+covered, research on how to best encode them for computer usage is
+still going on and they will be added eventually.
+This might
+eventually include not only Hieroglyphs and various historic
+Indo-European languages, but even some selected artistic scripts such
+as Tengwar, Cirth, and Klingon.
+UCS also covers a large number of
+graphical, typographical, mathematical, and scientific symbols,
+including those provided by TeX, Postscript, APL, MS-DOS, MS-Windows,
+Macintosh, OCR fonts, as well as many word processing and publishing
+systems, and more are being added.
+.P
+The UCS standard (ISO/IEC 10646) describes a
+31-bit character set architecture
+consisting of 128 24-bit
+.IR groups ,
+each divided into 256 16-bit
+.I planes
+made up of 256 8-bit
+.I rows
+with 256
+.I column
+positions, one for each character.
+Part 1 of the standard (ISO/IEC 10646-1)
+defines the first 65534 code positions (0x0000 to 0xfffd), which form
+the
+.I Basic Multilingual Plane
+(BMP), that is plane 0 in group 0.
+Part 2 of the standard (ISO/IEC 10646-2)
+adds characters to group 0 outside the BMP in several
+.I "supplementary planes"
+in the range 0x10000 to 0x10ffff.
+There are no plans to add characters
+beyond 0x10ffff to the standard, therefore of the entire code space,
+only a small fraction of group 0 will ever be actually used in the
+foreseeable future.
+The BMP contains all characters found in the
+commonly used other character sets.
+The supplemental planes added by
+ISO/IEC 10646-2 cover only more exotic characters for special scientific,
+dictionary printing, publishing industry, higher-level protocol and
+enthusiast needs.
+.P
+The representation of each UCS character as a 2-byte word is referred
+to as the UCS-2 form (only for BMP characters),
+whereas UCS-4 is the representation of each character by a 4-byte word.
+In addition, there exist two encoding forms UTF-8
+for backward compatibility with ASCII processing software and UTF-16
+for the backward-compatible handling of non-BMP characters up to
+0x10ffff by UCS-2 software.
+.P
+The UCS characters 0x0000 to 0x007f are identical to those of the
+classic US-ASCII
+character set and the characters in the range 0x0000 to 0x00ff
+are identical to those in
+ISO/IEC\~8859-1 (Latin-1).
+.SS Combining characters
+Some code points in UCS
+have been assigned to
+.IR "combining characters" .
+These are similar to the nonspacing accent keys on a typewriter.
+A combining character just adds an accent to the previous character.
+The most important accented characters have codes of their own in UCS,
+however, the combining character mechanism allows us to add accents
+and other diacritical marks to any character.
+The combining characters
+always follow the character which they modify.
+For example, the German
+character Umlaut-A ("Latin capital letter A with diaeresis") can
+either be represented by the precomposed UCS code 0x00c4, or
+alternatively as the combination of a normal "Latin capital letter A"
+followed by a "combining diaeresis": 0x0041 0x0308.
+.P
+Combining characters are essential for instance for encoding the Thai
+script or for mathematical typesetting and users of the International
+Phonetic Alphabet.
+.SS Implementation levels
+As not all systems are expected to support advanced mechanisms like
+combining characters, ISO/IEC 10646-1 specifies the following three
+.I implementation levels
+of UCS:
+.TP 0.9i
+Level 1
+Combining characters and Hangul Jamo
+(a variant encoding of the Korean script, where a Hangul syllable
+glyph is coded as a triplet or pair of vowel/consonant codes) are not
+supported.
+.TP
+Level 2
+In addition to level 1, combining characters are now allowed for some
+languages where they are essential (e.g., Thai, Lao, Hebrew,
+Arabic, Devanagari, Malayalam).
+.TP
+Level 3
+All UCS characters are supported.
+.P
+The Unicode 3.0 Standard
+published by the Unicode Consortium
+contains exactly the UCS Basic Multilingual Plane
+at implementation level 3, as described in ISO/IEC 10646-1:2000.
+Unicode 3.1 added the supplemental planes of ISO/IEC 10646-2.
+The Unicode standard and
+technical reports published by the Unicode Consortium provide much
+additional information on the semantics and recommended usages of
+various characters.
+They provide guidelines and algorithms for
+editing, sorting, comparing, normalizing, converting, and displaying
+Unicode strings.
+.SS Unicode under Linux
+Under GNU/Linux, the C type
+.I wchar_t
+is a signed 32-bit integer type.
+Its values are always interpreted
+by the C library as UCS
+code values (in all locales), a convention that is signaled by the GNU
+C library to applications by defining the constant
+.B __STDC_ISO_10646__
+as specified in the ISO C99 standard.
+.P
+UCS/Unicode can be used just like ASCII in input/output streams,
+terminal communication, plaintext files, filenames, and environment
+variables in the ASCII compatible UTF-8 multibyte encoding.
+To signal the use of UTF-8 as the character
+encoding to all applications, a suitable
+.I locale
+has to be selected via environment variables (e.g.,
+"LANG=en_GB.UTF-8").
+.P
+The
+.B nl_langinfo(CODESET)
+function returns the name of the selected encoding.
+Library functions such as
+.BR wctomb (3)
+and
+.BR mbsrtowcs (3)
+can be used to transform the internal
+.I wchar_t
+characters and strings into the system character encoding and back
+and
+.BR wcwidth (3)
+tells how many positions (0\[en]2) the cursor is advanced by the
+output of a character.
+.SS Private Use Areas (PUA)
+In the Basic Multilingual Plane,
+the range 0xe000 to 0xf8ff will never be assigned to any characters by
+the standard and is reserved for private usage.
+For the Linux
+community, this private area has been subdivided further into the
+range 0xe000 to 0xefff which can be used individually by any end-user
+and the Linux zone in the range 0xf000 to 0xf8ff where extensions are
+coordinated among all Linux users.
+The registry of the characters
+assigned to the Linux zone is maintained by LANANA and the registry
+itself is
+.I Documentation/admin\-guide/unicode.rst
+in the Linux kernel sources
+.\" commit 9d85025b0418163fae079c9ba8f8445212de8568
+(or
+.I Documentation/unicode.txt
+before Linux 4.10).
+.P
+Two other planes are reserved for private usage, plane 15
+(Supplementary Private Use Area-A, range 0xf0000 to 0xffffd)
+and plane 16 (Supplementary Private Use Area-B, range
+0x100000 to 0x10fffd).
+.SS Literature
+.IP \[bu] 3
+Information technology \[em] Universal Multiple-Octet Coded Character
+Set (UCS) \[em] Part 1: Architecture and Basic Multilingual Plane.
+International Standard ISO/IEC 10646-1, International Organization
+for Standardization, Geneva, 2000.
+.IP
+This is the official specification of UCS.
+Available from
+.UR http://www.iso.ch/
+.UE .
+.IP \[bu]
+The Unicode Standard, Version 3.0.
+The Unicode Consortium, Addison-Wesley,
+Reading, MA, 2000, ISBN 0-201-61633-5.
+.IP \[bu]
+S.\& Harbison, G.\& Steele. C: A Reference Manual. Fourth edition,
+Prentice Hall, Englewood Cliffs, 1995, ISBN 0-13-326224-3.
+.IP
+A good reference book about the C programming language.
+The fourth
+edition covers the 1994 Amendment 1 to the ISO C90 standard, which
+adds a large number of new C library functions for handling wide and
+multibyte character encodings, but it does not yet cover ISO C99,
+which improved wide and multibyte character support even further.
+.IP \[bu]
+Unicode Technical Reports.
+.RS
+.UR http://www.unicode.org\:/reports/
+.UE
+.RE
+.IP \[bu]
+Markus Kuhn: UTF-8 and Unicode FAQ for UNIX/Linux.
+.RS
+.UR http://www.cl.cam.ac.uk\:/\[ti]mgk25\:/unicode.html
+.UE
+.RE
+.IP \[bu]
+Bruno Haible: Unicode HOWTO.
+.RS
+.UR http://www.tldp.org\:/HOWTO\:/Unicode\-HOWTO.html
+.UE
+.RE
+.\" .SH AUTHOR
+.\" Markus Kuhn <mgk25@cl.cam.ac.uk>
+.SH SEE ALSO
+.BR locale (1),
+.BR setlocale (3),
+.BR charsets (7),
+.BR utf\-8 (7)
diff --git a/man/man7/units.7 b/man/man7/units.7
new file mode 100644
index 000000000..0aff62ce4
--- /dev/null
+++ b/man/man7/units.7
@@ -0,0 +1,108 @@
+'\" t
+.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH units 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+units \- decimal and binary prefixes
+.SH DESCRIPTION
+.SS Decimal prefixes
+The SI system of units uses prefixes that indicate powers of ten.
+A kilometer is 1000 meter, and a megawatt is 1000000 watt.
+Below the standard prefixes.
+.RS
+.TS
+l l l.
+Prefix	Name	Value
+q	quecto	10\[ha]\-30 = 0.000000000000000000000000000001
+r	ronto	10\[ha]\-27 = 0.000000000000000000000000001
+y	yocto	10\[ha]\-24 = 0.000000000000000000000001
+z	zepto	10\[ha]\-21 = 0.000000000000000000001
+a	atto	10\[ha]\-18 = 0.000000000000000001
+f	femto	10\[ha]\-15 = 0.000000000000001
+p	pico	10\[ha]\-12 = 0.000000000001
+n	nano	10\[ha]\-9  = 0.000000001
+\[mc]	micro	10\[ha]\-6  = 0.000001
+m	milli	10\[ha]\-3  = 0.001
+c	centi	10\[ha]\-2  = 0.01
+d	deci	10\[ha]\-1  = 0.1
+da	deka	10\[ha] 1  = 10
+h	hecto	10\[ha] 2  = 100
+k	kilo	10\[ha] 3  = 1000
+M	mega	10\[ha] 6  = 1000000
+G	giga	10\[ha] 9  = 1000000000
+T	tera	10\[ha]12  = 1000000000000
+P	peta	10\[ha]15  = 1000000000000000
+E	exa	10\[ha]18  = 1000000000000000000
+Z	zetta	10\[ha]21  = 1000000000000000000000
+Y	yotta	10\[ha]24  = 1000000000000000000000000
+R	ronna	10\[ha]27  = 1000000000000000000000000000
+Q	quetta	10\[ha]30  = 1000000000000000000000000000000
+.TE
+.RE
+.P
+The symbol for micro is the Greek letter mu, often written u
+in an ASCII context where this Greek letter is not available.
+.SS Binary prefixes
+The binary prefixes resemble the decimal ones,
+but have an additional \[aq]i\[aq]
+(and "Ki" starts with a capital \[aq]K\[aq]).
+The names are formed by taking the
+first syllable of the names of the decimal prefix with roughly the same
+size, followed by "bi" for "binary".
+.RS
+.TS
+l l l.
+Prefix	Name	Value
+Ki	kibi	2\[ha]10 = 1024
+Mi	mebi	2\[ha]20 = 1048576
+Gi	gibi	2\[ha]30 = 1073741824
+Ti	tebi	2\[ha]40 = 1099511627776
+Pi	pebi	2\[ha]50 = 1125899906842624
+Ei	exbi	2\[ha]60 = 1152921504606846976
+Zi	zebi	2\[ha]70 = 1180591620717411303424
+Yi	yobi	2\[ha]80 = 1208925819614629174706176
+.TE
+.RE
+.SS Discussion
+Before these binary prefixes were introduced, it was fairly
+common to use k=1000 and K=1024, just like b=bit, B=byte.
+Unfortunately, the M is capital already, and cannot be
+capitalized to indicate binary-ness.
+.P
+At first that didn't matter too much, since memory modules
+and disks came in sizes that were powers of two, so everyone
+knew that in such contexts "kilobyte" and "megabyte" meant
+1024 and 1048576 bytes, respectively.
+What originally was a
+sloppy use of the prefixes "kilo" and "mega" started to become
+regarded as the "real true meaning" when computers were involved.
+But then disk technology changed, and disk sizes became arbitrary numbers.
+After a period of uncertainty all disk manufacturers settled on the
+standard, namely k=1000, M=1000\ k, G=1000\ M.
+.P
+The situation was messy: in the 14k4 modems, k=1000; in the 1.44\ MB
+.\" also common: 14.4k modem
+diskettes, M=1024000; and so on.
+In 1998 the IEC approved the standard
+that defines the binary prefixes given above, enabling people
+to be precise and unambiguous.
+.P
+Thus, today, MB = 1000000\ B and MiB = 1048576\ B.
+.P
+In the free software world programs are slowly
+being changed to conform.
+When the Linux kernel boots and says
+.P
+.in +4n
+.EX
+hda: 120064896 sectors (61473 MB) w/2048KiB Cache
+.EE
+.in
+.P
+the MB are megabytes and the KiB are kibibytes.
+.SH SEE ALSO
+.UR https://www.bipm.org/\:documents/\:20126/\:41483022/\:SI\-Brochure\-9.pdf
+The International System of Units
+.UE .
diff --git a/man/man7/unix.7 b/man/man7/unix.7
new file mode 100644
index 000000000..642b0b37e
--- /dev/null
+++ b/man/man7/unix.7
@@ -0,0 +1,1227 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>,
+.\" Copyright (C) 2008-2014, Michael Kerrisk <mtk.manpages@gmail.com>,
+.\" and Copyright (C) 2016, Heinrich Schuchardt <xypron.glpk@gmx.de>
+.\"
+.\" Modified, 2003-12-02, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\" Modified, 2003-09-23, Adam Langley
+.\" Modified, 2004-05-27, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"	Added SOCK_SEQPACKET
+.\" 2008-05-27, mtk, Provide a clear description of the three types of
+.\"     address that can appear in the sockaddr_un structure: pathname,
+.\"     unnamed, and abstract.
+.\"
+.TH UNIX 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+unix \- sockets for local interprocess communication
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <sys/un.h>
+.P
+.IB unix_socket " = socket(AF_UNIX, type, 0);"
+.IB error " = socketpair(AF_UNIX, type, 0, int *" sv ");"
+.fi
+.SH DESCRIPTION
+The
+.B AF_UNIX
+(also known as
+.BR AF_LOCAL )
+socket family is used to communicate between processes on the same machine
+efficiently.
+Traditionally, UNIX domain sockets can be either unnamed,
+or bound to a filesystem pathname (marked as being of type socket).
+Linux also supports an abstract namespace which is independent of the
+filesystem.
+.P
+Valid socket types in the UNIX domain are:
+.BR SOCK_STREAM ,
+for a stream-oriented socket;
+.BR SOCK_DGRAM ,
+for a datagram-oriented socket that preserves message boundaries
+(as on most UNIX implementations, UNIX domain datagram
+sockets are always reliable and don't reorder datagrams);
+and (since Linux 2.6.4)
+.BR SOCK_SEQPACKET ,
+for a sequenced-packet socket that is connection-oriented,
+preserves message boundaries,
+and delivers messages in the order that they were sent.
+.P
+UNIX domain sockets support passing file descriptors or process credentials
+to other processes using ancillary data.
+.SS Address format
+A UNIX domain socket address is represented in the following structure:
+.P
+.in +4n
+.EX
+.\" #define UNIX_PATH_MAX    108
+.\"
+struct sockaddr_un {
+    sa_family_t sun_family;               /* AF_UNIX */
+    char        sun_path[108];            /* Pathname */
+};
+.EE
+.in
+.P
+The
+.I sun_family
+field always contains
+.BR AF_UNIX .
+On Linux,
+.I sun_path
+is 108 bytes in size; see also BUGS, below.
+.P
+Various system calls (for example,
+.BR bind (2),
+.BR connect (2),
+and
+.BR sendto (2))
+take a
+.I sockaddr_un
+argument as input.
+Some other system calls (for example,
+.BR getsockname (2),
+.BR getpeername (2),
+.BR recvfrom (2),
+and
+.BR accept (2))
+return an argument of this type.
+.P
+Three types of address are distinguished in the
+.I sockaddr_un
+structure:
+.TP
+pathname
+a UNIX domain socket can be bound to a null-terminated
+filesystem pathname using
+.BR bind (2).
+When the address of a pathname socket is returned
+(by one of the system calls noted above),
+its length is
+.IP
+.in +4n
+.EX
+offsetof(struct sockaddr_un, sun_path) + strlen(sun_path) + 1
+.EE
+.in
+.IP
+and
+.I sun_path
+contains the null-terminated pathname.
+(On Linux, the above
+.BR offsetof ()
+expression equates to the same value as
+.IR sizeof(sa_family_t) ,
+but some other implementations include other fields before
+.IR sun_path ,
+so the
+.BR offsetof ()
+expression more portably describes the size of the address structure.)
+.IP
+For further details of pathname sockets, see below.
+.TP
+unnamed
+A stream socket that has not been bound to a pathname using
+.BR bind (2)
+has no name.
+Likewise, the two sockets created by
+.BR socketpair (2)
+are unnamed.
+When the address of an unnamed socket is returned,
+its length is
+.IR "sizeof(sa_family_t)" ,
+and
+.I sun_path
+should not be inspected.
+.\" There is quite some variation across implementations: FreeBSD
+.\" says the length is 16 bytes, HP-UX 11 says it's zero bytes.
+.TP
+abstract
+an abstract socket address is distinguished (from a pathname socket)
+by the fact that
+.I sun_path[0]
+is a null byte (\[aq]\e0\[aq]).
+The socket's address in this namespace is given by the additional
+bytes in
+.I sun_path
+that are covered by the specified length of the address structure.
+(Null bytes in the name have no special significance.)
+The name has no connection with filesystem pathnames.
+When the address of an abstract socket is returned,
+the returned
+.I addrlen
+is greater than
+.I sizeof(sa_family_t)
+(i.e., greater than 2), and the name of the socket is contained in
+the first
+.I (addrlen \- sizeof(sa_family_t))
+bytes of
+.IR sun_path .
+.SS Pathname sockets
+When binding a socket to a pathname, a few rules should be observed
+for maximum portability and ease of coding:
+.IP \[bu] 3
+The pathname in
+.I sun_path
+should be null-terminated.
+.IP \[bu]
+The length of the pathname, including the terminating null byte,
+should not exceed the size of
+.IR sun_path .
+.IP \[bu]
+The
+.I addrlen
+argument that describes the enclosing
+.I sockaddr_un
+structure should have a value of at least:
+.IP
+.in +4n
+.EX
+offsetof(struct sockaddr_un, sun_path)+strlen(addr.sun_path)+1
+.EE
+.in
+.IP
+or, more simply,
+.I addrlen
+can be specified as
+.IR "sizeof(struct sockaddr_un)" .
+.P
+There is some variation in how implementations handle UNIX domain
+socket addresses that do not follow the above rules.
+For example, some (but not all) implementations
+.\" Linux does this, including for the case where the supplied path
+.\" is 108 bytes
+append a null terminator if none is present in the supplied
+.IR sun_path .
+.P
+When coding portable applications,
+keep in mind that some implementations
+.\" HP-UX
+have
+.I sun_path
+as short as 92 bytes.
+.\" Modern BSDs generally have 104, Tru64 and AIX have 104,
+.\" Solaris and Irix have 108
+.P
+Various system calls
+.RB ( accept (2),
+.BR recvfrom (2),
+.BR getsockname (2),
+.BR getpeername (2))
+return socket address structures.
+When applied to UNIX domain sockets, the value-result
+.I addrlen
+argument supplied to the call should be initialized as above.
+Upon return, the argument is set to indicate the
+.I actual
+size of the address structure.
+The caller should check the value returned in this argument:
+if the output value exceeds the input value,
+then there is no guarantee that a null terminator is present in
+.IR sun_path .
+(See BUGS.)
+.\"
+.SS Pathname socket ownership and permissions
+In the Linux implementation,
+pathname sockets honor the permissions of the directory they are in.
+Creation of a new socket fails if the process does not have write and
+search (execute) permission on the directory in which the socket is created.
+.P
+On Linux,
+connecting to a stream socket object requires write permission on that socket;
+sending a datagram to a datagram socket likewise
+requires write permission on that socket.
+POSIX does not make any statement about the effect of the permissions
+on a socket file, and on some systems (e.g., older BSDs),
+the socket permissions are ignored.
+Portable programs should not rely on
+this feature for security.
+.P
+When creating a new socket, the owner and group of the socket file
+are set according to the usual rules.
+The socket file has all permissions enabled,
+other than those that are turned off by the process
+.BR umask (2).
+.P
+The owner, group, and permissions of a pathname socket can be changed (using
+.BR chown (2)
+and
+.BR chmod (2)).
+.\" However, fchown() and fchmod() do not seem to have an effect
+.\"
+.SS Abstract sockets
+Socket permissions have no meaning for abstract sockets:
+the process
+.BR umask (2)
+has no effect when binding an abstract socket,
+and changing the ownership and permissions of the object (via
+.BR fchown (2)
+and
+.BR fchmod (2))
+has no effect on the accessibility of the socket.
+.P
+Abstract sockets automatically disappear when all open references
+to the socket are closed.
+.P
+The abstract socket namespace is a nonportable Linux extension.
+.\"
+.SS Socket options
+For historical reasons, these socket options are specified with a
+.B SOL_SOCKET
+type even though they are
+.B AF_UNIX
+specific.
+They can be set with
+.BR setsockopt (2)
+and read with
+.BR getsockopt (2)
+by specifying
+.B SOL_SOCKET
+as the socket family.
+.TP
+.B SO_PASSCRED
+Enabling this socket option causes receipt of the credentials of
+the sending process in an
+.B SCM_CREDENTIALS ancillary
+message in each subsequently received message.
+The returned credentials are those specified by the sender using
+.BR SCM_CREDENTIALS ,
+or a default that includes the sender's PID, real user ID, and real group ID,
+if the sender did not specify
+.B SCM_CREDENTIALS
+ancillary data.
+.IP
+When this option is set and the socket is not yet connected,
+a unique name in the abstract namespace will be generated automatically.
+.IP
+The value given as an argument to
+.BR setsockopt (2)
+and returned as the result of
+.BR getsockopt (2)
+is an integer boolean flag.
+.TP
+.B SO_PASSSEC
+Enables receiving of the SELinux security label of the peer socket
+in an ancillary message of type
+.B SCM_SECURITY
+(see below).
+.IP
+The value given as an argument to
+.BR setsockopt (2)
+and returned as the result of
+.BR getsockopt (2)
+is an integer boolean flag.
+.IP
+The
+.B SO_PASSSEC
+option is supported for UNIX domain datagram sockets
+.\" commit 877ce7c1b3afd69a9b1caeb1b9964c992641f52a
+since Linux 2.6.18;
+support for UNIX domain stream sockets was added
+.\" commit 37a9a8df8ce9de6ea73349c9ac8bdf6ba4ec4f70
+in Linux 4.2.
+.TP
+.B SO_PEEK_OFF
+See
+.BR socket (7).
+.TP
+.B SO_PEERCRED
+This read-only socket option returns the
+credentials of the peer process connected to this socket.
+The returned credentials are those that were in effect at the time
+of the call to
+.BR connect (2),
+.BR listen (2),
+or
+.BR socketpair (2).
+.IP
+The argument to
+.BR getsockopt (2)
+is a pointer to a
+.I ucred
+structure; define the
+.B _GNU_SOURCE
+feature test macro to obtain the definition of that structure from
+.IR <sys/socket.h> .
+.IP
+The use of this option is possible only for connected
+.B AF_UNIX
+stream sockets and for
+.B AF_UNIX
+stream and datagram socket pairs created using
+.BR socketpair (2).
+.TP
+.B SO_PEERSEC
+This read-only socket option returns the
+security context of the peer socket connected to this socket.
+By default, this will be the same as the security context of
+the process that created the peer socket unless overridden
+by the policy or by a process with the required permissions.
+.IP
+The argument to
+.BR getsockopt (2)
+is a pointer to a buffer of the specified length in bytes
+into which the security context string will be copied.
+If the buffer length is less than the length of the security
+context string, then
+.BR getsockopt (2)
+returns \-1, sets
+.I errno
+to
+.BR ERANGE ,
+and returns the required length via
+.IR optlen .
+The caller should allocate at least
+.B NAME_MAX
+bytes for the buffer initially, although this is not guaranteed
+to be sufficient.
+Resizing the buffer to the returned length
+and retrying may be necessary.
+.IP
+The security context string may include a terminating null character
+in the returned length, but is not guaranteed to do so: a security
+context "foo" might be represented as either {'f','o','o'} of length 3
+or {'f','o','o','\\0'} of length 4, which are considered to be
+interchangeable.
+The string is printable, does not contain non-terminating null characters,
+and is in an unspecified encoding (in particular, it
+is not guaranteed to be ASCII or UTF-8).
+.IP
+The use of this option for sockets in the
+.B AF_UNIX
+address family is supported since Linux 2.6.2 for connected stream sockets,
+and since Linux 4.18
+.\" commit 0b811db2cb2aabc910e53d34ebb95a15997c33e7
+also for stream and datagram socket pairs created using
+.BR socketpair (2).
+.\"
+.SS Autobind feature
+If a
+.BR bind (2)
+call specifies
+.I addrlen
+as
+.IR sizeof(sa_family_t) ,
+.\" i.e., sizeof(short)
+or the
+.B SO_PASSCRED
+socket option was specified for a socket that was
+not explicitly bound to an address,
+then the socket is autobound to an abstract address.
+The address consists of a null byte
+followed by 5 bytes in the character set
+.IR [0\-9a\-f] .
+Thus, there is a limit of 2\[ha]20 autobind addresses.
+(From Linux 2.1.15, when the autobind feature was added,
+8 bytes were used, and the limit was thus 2\[ha]32 autobind addresses.
+The change to 5 bytes came in Linux 2.3.15.)
+.SS Sockets API
+The following paragraphs describe domain-specific details and
+unsupported features of the sockets API for UNIX domain sockets on Linux.
+.P
+UNIX domain sockets do not support the transmission of
+out-of-band data (the
+.B MSG_OOB
+flag for
+.BR send (2)
+and
+.BR recv (2)).
+.P
+The
+.BR send (2)
+.B MSG_MORE
+flag is not supported by UNIX domain sockets.
+.P
+Before Linux 3.4,
+.\" commit 9f6f9af7694ede6314bed281eec74d588ba9474f
+the use of
+.B MSG_TRUNC
+in the
+.I flags
+argument of
+.BR recv (2)
+was not supported by UNIX domain sockets.
+.P
+The
+.B SO_SNDBUF
+socket option does have an effect for UNIX domain sockets, but the
+.B SO_RCVBUF
+option does not.
+For datagram sockets, the
+.B SO_SNDBUF
+value imposes an upper limit on the size of outgoing datagrams.
+This limit is calculated as the doubled (see
+.BR socket (7))
+option value less 32 bytes used for overhead.
+.SS Ancillary messages
+Ancillary data is sent and received using
+.BR sendmsg (2)
+and
+.BR recvmsg (2).
+For historical reasons, the ancillary message types listed below
+are specified with a
+.B SOL_SOCKET
+type even though they are
+.B AF_UNIX
+specific.
+To send them, set the
+.I cmsg_level
+field of the struct
+.I cmsghdr
+to
+.B SOL_SOCKET
+and the
+.I cmsg_type
+field to the type.
+For more information, see
+.BR cmsg (3).
+.TP
+.B SCM_RIGHTS
+Send or receive a set of open file descriptors from another process.
+The data portion contains an integer array of the file descriptors.
+.IP
+Commonly, this operation is referred to as "passing a file descriptor"
+to another process.
+However, more accurately,
+what is being passed is a reference to an open file description (see
+.BR open (2)),
+and in the receiving process it is likely that a different
+file descriptor number will be used.
+Semantically, this operation is equivalent to duplicating
+.RB ( dup (2))
+a file descriptor into the file descriptor table of another process.
+.IP
+If the buffer used to receive the ancillary data containing
+file descriptors is too small (or is absent),
+then the ancillary data is truncated (or discarded)
+and the excess file descriptors are automatically closed
+in the receiving process.
+.IP
+If the number of file descriptors received in the ancillary data would
+cause the process to exceed its
+.B RLIMIT_NOFILE
+resource limit (see
+.BR getrlimit (2)),
+the excess file descriptors are automatically closed
+in the receiving process.
+.IP
+The kernel constant
+.B SCM_MAX_FD
+defines a limit on the number of file descriptors in the array.
+Attempting to send an array larger than this limit causes
+.BR sendmsg (2)
+to fail with the error
+.BR EINVAL .
+.B SCM_MAX_FD
+has the value 253
+.\" commit bba14de98753cb6599a2dae0e520714b2153522d
+(or 255 before Linux 2.6.38).
+.TP
+.B SCM_CREDENTIALS
+Send or receive UNIX credentials.
+This can be used for authentication.
+The credentials are passed as a
+.I struct ucred
+ancillary message.
+This structure is defined in
+.I <sys/socket.h>
+as follows:
+.IP
+.in +4n
+.EX
+struct ucred {
+    pid_t pid;    /* Process ID of the sending process */
+    uid_t uid;    /* User ID of the sending process */
+    gid_t gid;    /* Group ID of the sending process */
+};
+.EE
+.in
+.IP
+Since glibc 2.8, the
+.B _GNU_SOURCE
+feature test macro must be defined (before including
+.I any
+header files) in order to obtain the definition
+of this structure.
+.IP
+The credentials which the sender specifies are checked by the kernel.
+A privileged process is allowed to specify values that do not match its own.
+The sender must specify its own process ID (unless it has the capability
+.BR CAP_SYS_ADMIN ,
+in which case the PID of any existing process may be specified),
+its real user ID, effective user ID, or saved set-user-ID (unless it has
+.BR CAP_SETUID ),
+and its real group ID, effective group ID, or saved set-group-ID
+(unless it has
+.BR CAP_SETGID ).
+.IP
+To receive a
+.I struct ucred
+message, the
+.B SO_PASSCRED
+option must be enabled on the socket.
+.TP
+.B SCM_SECURITY
+Receive the SELinux security context (the security label)
+of the peer socket.
+The received ancillary data is a null-terminated string containing
+the security context.
+The receiver should allocate at least
+.B NAME_MAX
+bytes in the data portion of the ancillary message for this data.
+.IP
+To receive the security context, the
+.B SO_PASSSEC
+option must be enabled on the socket (see above).
+.P
+When sending ancillary data with
+.BR sendmsg (2),
+only one item of each of the above types may be included in the sent message.
+.P
+At least one byte of real data should be sent when sending ancillary data.
+On Linux, this is required to successfully send ancillary data over
+a UNIX domain stream socket.
+When sending ancillary data over a UNIX domain datagram socket,
+it is not necessary on Linux to send any accompanying real data.
+However, portable applications should also include at least one byte
+of real data when sending ancillary data over a datagram socket.
+.P
+When receiving from a stream socket,
+ancillary data forms a kind of barrier for the received data.
+For example, suppose that the sender transmits as follows:
+.P
+.RS
+.PD 0
+.IP (1) 5
+.BR sendmsg (2)
+of four bytes, with no ancillary data.
+.IP (2)
+.BR sendmsg (2)
+of one byte, with ancillary data.
+.IP (3)
+.BR sendmsg (2)
+of four bytes, with no ancillary data.
+.PD
+.RE
+.P
+Suppose that the receiver now performs
+.BR recvmsg (2)
+calls each with a buffer size of 20 bytes.
+The first call will receive five bytes of data,
+along with the ancillary data sent by the second
+.BR sendmsg (2)
+call.
+The next call will receive the remaining four bytes of data.
+.P
+If the space allocated for receiving incoming ancillary data is too small
+then the ancillary data is truncated to the number of headers
+that will fit in the supplied buffer (or, in the case of an
+.B SCM_RIGHTS
+file descriptor list, the list of file descriptors may be truncated).
+If no buffer is provided for incoming ancillary data (i.e., the
+.I msg_control
+field of the
+.I msghdr
+structure supplied to
+.BR recvmsg (2)
+is NULL),
+then the incoming ancillary data is discarded.
+In both of these cases, the
+.B MSG_CTRUNC
+flag will be set in the
+.I msg.msg_flags
+value returned by
+.BR recvmsg (2).
+.\"
+.SS Ioctls
+The following
+.BR ioctl (2)
+calls return information in
+.IR value .
+The correct syntax is:
+.P
+.RS
+.nf
+.BI int " value";
+.IB error " = ioctl(" unix_socket ", " ioctl_type ", &" value ");"
+.fi
+.RE
+.P
+.I ioctl_type
+can be:
+.TP
+.B SIOCINQ
+For
+.B SOCK_STREAM
+sockets, this call returns the number of unread bytes in the receive buffer.
+The socket must not be in LISTEN state, otherwise an error
+.RB ( EINVAL )
+is returned.
+.B SIOCINQ
+is defined in
+.IR <linux/sockios.h> .
+.\" FIXME . https://www.sourceware.org/bugzilla/show_bug.cgi?id=12002,
+.\" filed 2010-09-10, may cause SIOCINQ to be defined in glibc headers
+Alternatively,
+you can use the synonymous
+.BR FIONREAD ,
+defined in
+.IR <sys/ioctl.h> .
+.\" SIOCOUTQ also has an effect for UNIX domain sockets, but not
+.\" quite what userland might expect. It seems to return the number
+.\" of bytes allocated for buffers containing pending output.
+.\" That number is normally larger than the number of bytes of pending
+.\" output. Since this info is, from userland's point of view, imprecise,
+.\" and it may well change, probably best not to document this now.
+For
+.B SOCK_DGRAM
+sockets,
+the returned value is the same as
+for Internet domain datagram sockets;
+see
+.BR udp (7).
+.SH ERRORS
+.TP
+.B EADDRINUSE
+The specified local address is already in use or the filesystem socket
+object already exists.
+.TP
+.B EBADF
+This error can occur for
+.BR sendmsg (2)
+when sending a file descriptor as ancillary data over
+a UNIX domain socket (see the description of
+.BR SCM_RIGHTS ,
+above), and indicates that the file descriptor number that
+is being sent is not valid (e.g., it is not an open file descriptor).
+.TP
+.B ECONNREFUSED
+The remote address specified by
+.BR connect (2)
+was not a listening socket.
+This error can also occur if the target pathname is not a socket.
+.TP
+.B ECONNRESET
+Remote socket was unexpectedly closed.
+.TP
+.B EFAULT
+User memory address was not valid.
+.TP
+.B EINVAL
+Invalid argument passed.
+A common cause is that the value
+.B AF_UNIX
+was not specified in the
+.I sun_type
+field of passed addresses, or the socket was in an
+invalid state for the applied operation.
+.TP
+.B EISCONN
+.BR connect (2)
+called on an already connected socket or a target address was
+specified on a connected socket.
+.TP
+.B ENFILE
+The system-wide limit on the total number of open files has been reached.
+.TP
+.B ENOENT
+The pathname in the remote address specified to
+.BR connect (2)
+did not exist.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ENOTCONN
+Socket operation needs a target address, but the socket is not connected.
+.TP
+.B EOPNOTSUPP
+Stream operation called on non-stream oriented socket or tried to
+use the out-of-band data option.
+.TP
+.B EPERM
+The sender passed invalid credentials in the
+.IR "struct ucred" .
+.TP
+.B EPIPE
+Remote socket was closed on a stream socket.
+If enabled, a
+.B SIGPIPE
+is sent as well.
+This can be avoided by passing the
+.B MSG_NOSIGNAL
+flag to
+.BR send (2)
+or
+.BR sendmsg (2).
+.TP
+.B EPROTONOSUPPORT
+Passed protocol is not
+.BR AF_UNIX .
+.TP
+.B EPROTOTYPE
+Remote socket does not match the local socket type
+.RB ( SOCK_DGRAM
+versus
+.BR SOCK_STREAM ).
+.TP
+.B ESOCKTNOSUPPORT
+Unknown socket type.
+.TP
+.B ESRCH
+While sending an ancillary message containing credentials
+.RB ( SCM_CREDENTIALS ),
+the caller specified a PID that does not match any existing process.
+.TP
+.B ETOOMANYREFS
+This error can occur for
+.BR sendmsg (2)
+when sending a file descriptor as ancillary data over
+a UNIX domain socket (see the description of
+.BR SCM_RIGHTS ,
+above).
+It occurs if the number of "in-flight" file descriptors exceeds the
+.B RLIMIT_NOFILE
+resource limit and the caller does not have the
+.B CAP_SYS_RESOURCE
+capability.
+An in-flight file descriptor is one that has been sent using
+.BR sendmsg (2)
+but has not yet been accepted in the recipient process using
+.BR recvmsg (2).
+.IP
+This error is diagnosed since mainline Linux 4.5
+(and in some earlier kernel versions where the fix has been backported).
+.\" commit 712f4aad406bb1ed67f3f98d04c044191f0ff593
+In earlier kernel versions,
+it was possible to place an unlimited number of file descriptors in flight,
+by sending each file descriptor with
+.BR sendmsg (2)
+and then closing the file descriptor so that it was not accounted against the
+.B RLIMIT_NOFILE
+resource limit.
+.P
+Other errors can be generated by the generic socket layer or
+by the filesystem while generating a filesystem socket object.
+See the appropriate manual pages for more information.
+.SH VERSIONS
+.B SCM_CREDENTIALS
+and the abstract namespace were introduced with Linux 2.2 and should not
+be used in portable programs.
+(Some BSD-derived systems also support credential passing,
+but the implementation details differ.)
+.SH NOTES
+Binding to a socket with a filename creates a socket
+in the filesystem that must be deleted by the caller when it is no
+longer needed (using
+.BR unlink (2)).
+The usual UNIX close-behind semantics apply; the socket can be unlinked
+at any time and will be finally removed from the filesystem when the last
+reference to it is closed.
+.P
+To pass file descriptors or credentials over a
+.B SOCK_STREAM
+socket, you must
+send or receive at least one byte of nonancillary data in the same
+.BR sendmsg (2)
+or
+.BR recvmsg (2)
+call.
+.P
+UNIX domain stream sockets do not support the notion of out-of-band data.
+.\"
+.SH BUGS
+When binding a socket to an address,
+Linux is one of the implementations that append a null terminator
+if none is supplied in
+.IR sun_path .
+In most cases this is unproblematic:
+when the socket address is retrieved,
+it will be one byte longer than that supplied when the socket was bound.
+However, there is one case where confusing behavior can result:
+if 108 non-null bytes are supplied when a socket is bound,
+then the addition of the null terminator takes the length of
+the pathname beyond
+.IR sizeof(sun_path) .
+Consequently, when retrieving the socket address
+(for example, via
+.BR accept (2)),
+.\" The behavior on Solaris is quite similar.
+if the input
+.I addrlen
+argument for the retrieving call is specified as
+.IR "sizeof(struct sockaddr_un)" ,
+then the returned address structure
+.I won't
+have a null terminator in
+.IR sun_path .
+.P
+In addition, some implementations
+.\" i.e., traditional BSD
+don't require a null terminator when binding a socket (the
+.I addrlen
+argument is used to determine the length of
+.IR sun_path )
+and when the socket address is retrieved on these implementations,
+there is no null terminator in
+.IR sun_path .
+.P
+Applications that retrieve socket addresses can (portably) code
+to handle the possibility that there is no null terminator in
+.I sun_path
+by respecting the fact that the number of valid bytes in the pathname is:
+.P
+.in +4n
+.EX
+strnlen(addr.sun_path, addrlen \- offsetof(sockaddr_un, sun_path))
+.EE
+.in
+.\" The following patch to amend kernel behavior was rejected:
+.\" http://thread.gmane.org/gmane.linux.kernel.api/2437
+.\" Subject: [patch] Fix handling of overlength pathname in AF_UNIX sun_path
+.\" 2012-04-17
+.\" And there was a related discussion in the Austin list:
+.\" http://thread.gmane.org/gmane.comp.standards.posix.austin.general/5735
+.\" Subject: Having a sun_path with no null terminator
+.\" 2012-04-18
+.\"
+.\" FIXME . Track http://austingroupbugs.net/view.php?id=561
+.P
+Alternatively, an application can retrieve
+the socket address by allocating a buffer of size
+.I "sizeof(struct sockaddr_un)+1"
+that is zeroed out before the retrieval.
+The retrieving call can specify
+.I addrlen
+as
+.IR "sizeof(struct sockaddr_un)" ,
+and the extra zero byte ensures that there will be
+a null terminator for the string returned in
+.IR sun_path :
+.P
+.in +4n
+.EX
+void *addrp;
+\&
+addrlen = sizeof(struct sockaddr_un);
+addrp = malloc(addrlen + 1);
+if (addrp == NULL)
+    /* Handle error */ ;
+memset(addrp, 0, addrlen + 1);
+\&
+if (getsockname(sfd, (struct sockaddr *) addrp, &addrlen)) == \-1)
+    /* handle error */ ;
+\&
+printf("sun_path = %s\en", ((struct sockaddr_un *) addrp)\->sun_path);
+.EE
+.in
+.P
+This sort of messiness can be avoided if it is guaranteed
+that the applications that
+.I create
+pathname sockets follow the rules outlined above under
+.IR "Pathname sockets" .
+.SH EXAMPLES
+The following code demonstrates the use of sequenced-packet
+sockets for local interprocess communication.
+It consists of two programs.
+The server program waits for a connection from the client program.
+The client sends each of its command-line arguments in separate messages.
+The server treats the incoming messages as integers and adds them up.
+The client sends the command string "END".
+The server sends back a message containing the sum of the client's integers.
+The client prints the sum and exits.
+The server waits for the next client to connect.
+To stop the server, the client is called with the command-line argument "DOWN".
+.P
+The following output was recorded while running the server in the background
+and repeatedly executing the client.
+Execution of the server program ends when it receives the "DOWN" command.
+.SS Example output
+.in +4n
+.EX
+$ \fB./server &\fP
+[1] 25887
+$ \fB./client 3 4\fP
+Result = 7
+$ \fB./client 11 \-5\fP
+Result = 6
+$ \fB./client DOWN\fP
+Result = 0
+[1]+  Done                    ./server
+$
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (connection.h)
+.EX
+/*
+ * File connection.h
+ */
+#ifndef CONNECTION_H
+#define CONNECTION_H
+\&
+#define SOCKET_NAME "/tmp/9Lq7BNBnBycd6nxy.socket"
+#define BUFFER_SIZE 12
+\&
+#endif  // include guard
+.EE
+.\" SRC END
+.P
+.\" SRC BEGIN (server.c)
+.EX
+/*
+ * File server.c
+ */
+\&
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+\&
+#include "connection.h"
+\&
+int
+main(void)
+{
+    int                 down_flag = 0;
+    int                 ret;
+    int                 connection_socket;
+    int                 data_socket;
+    int                 result;
+    ssize_t             r, w;
+    struct sockaddr_un  name;
+    char                buffer[BUFFER_SIZE];
+\&
+    /* Create local socket. */
+\&
+    connection_socket = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+    if (connection_socket == \-1) {
+        perror("socket");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * For portability clear the whole structure, since some
+     * implementations have additional (nonstandard) fields in
+     * the structure.
+     */
+\&
+    memset(&name, 0, sizeof(name));
+\&
+    /* Bind socket to socket name. */
+\&
+    name.sun_family = AF_UNIX;
+    strncpy(name.sun_path, SOCKET_NAME, sizeof(name.sun_path) \- 1);
+\&
+    ret = bind(connection_socket, (const struct sockaddr *) &name,
+               sizeof(name));
+    if (ret == \-1) {
+        perror("bind");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * Prepare for accepting connections. The backlog size is set
+     * to 20. So while one request is being processed other requests
+     * can be waiting.
+     */
+\&
+    ret = listen(connection_socket, 20);
+    if (ret == \-1) {
+        perror("listen");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* This is the main loop for handling connections. */
+\&
+    for (;;) {
+\&
+        /* Wait for incoming connection. */
+\&
+        data_socket = accept(connection_socket, NULL, NULL);
+        if (data_socket == \-1) {
+            perror("accept");
+            exit(EXIT_FAILURE);
+        }
+\&
+        result = 0;
+        for (;;) {
+\&
+            /* Wait for next data packet. */
+\&
+            r = read(data_socket, buffer, sizeof(buffer));
+            if (r == \-1) {
+                perror("read");
+                exit(EXIT_FAILURE);
+            }
+\&
+            /* Ensure buffer is 0\-terminated. */
+\&
+            buffer[sizeof(buffer) \- 1] = 0;
+\&
+            /* Handle commands. */
+\&
+            if (!strncmp(buffer, "DOWN", sizeof(buffer))) {
+                down_flag = 1;
+                continue;
+            }
+\&
+            if (!strncmp(buffer, "END", sizeof(buffer))) {
+                break;
+            }
+\&
+            if (down_flag) {
+                continue;
+            }
+\&
+            /* Add received summand. */
+\&
+            result += atoi(buffer);
+        }
+\&
+        /* Send result. */
+\&
+        sprintf(buffer, "%d", result);
+        w = write(data_socket, buffer, sizeof(buffer));
+        if (w == \-1) {
+            perror("write");
+            exit(EXIT_FAILURE);
+        }
+\&
+        /* Close socket. */
+\&
+        close(data_socket);
+\&
+        /* Quit on DOWN command. */
+\&
+        if (down_flag) {
+            break;
+        }
+    }
+\&
+    close(connection_socket);
+\&
+    /* Unlink the socket. */
+\&
+    unlink(SOCKET_NAME);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.P
+.\" SRC BEGIN (client.c)
+.EX
+/*
+ * File client.c
+ */
+\&
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+\&
+#include "connection.h"
+\&
+int
+main(int argc, char *argv[])
+{
+    int                 ret;
+    int                 data_socket;
+    ssize_t             r, w;
+    struct sockaddr_un  addr;
+    char                buffer[BUFFER_SIZE];
+\&
+    /* Create local socket. */
+\&
+    data_socket = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+    if (data_socket == \-1) {
+        perror("socket");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /*
+     * For portability clear the whole structure, since some
+     * implementations have additional (nonstandard) fields in
+     * the structure.
+     */
+\&
+    memset(&addr, 0, sizeof(addr));
+\&
+    /* Connect socket to socket address. */
+\&
+    addr.sun_family = AF_UNIX;
+    strncpy(addr.sun_path, SOCKET_NAME, sizeof(addr.sun_path) \- 1);
+\&
+    ret = connect(data_socket, (const struct sockaddr *) &addr,
+                   sizeof(addr));
+    if (ret == \-1) {
+        fprintf(stderr, "The server is down.\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Send arguments. */
+\&
+    for (int i = 1; i < argc; ++i) {
+        w = write(data_socket, argv[i], strlen(argv[i]) + 1);
+        if (w == \-1) {
+            perror("write");
+            break;
+        }
+    }
+\&
+    /* Request result. */
+\&
+    strcpy(buffer, "END");
+    w = write(data_socket, buffer, strlen(buffer) + 1);
+    if (w == \-1) {
+        perror("write");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Receive result. */
+\&
+    r = read(data_socket, buffer, sizeof(buffer));
+    if (r == \-1) {
+        perror("read");
+        exit(EXIT_FAILURE);
+    }
+\&
+    /* Ensure buffer is 0\-terminated. */
+\&
+    buffer[sizeof(buffer) \- 1] = 0;
+\&
+    printf("Result = %s\en", buffer);
+\&
+    /* Close socket. */
+\&
+    close(data_socket);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.P
+For examples of the use of
+.BR SCM_RIGHTS ,
+see
+.BR cmsg (3)
+and
+.BR seccomp_unotify (2).
+.SH SEE ALSO
+.BR recvmsg (2),
+.BR sendmsg (2),
+.BR socket (2),
+.BR socketpair (2),
+.BR cmsg (3),
+.BR capabilities (7),
+.BR credentials (7),
+.BR socket (7),
+.BR udp (7)
diff --git a/man/man7/uri.7 b/man/man7/uri.7
new file mode 100644
index 000000000..d76f3fc05
--- /dev/null
+++ b/man/man7/uri.7
@@ -0,0 +1,761 @@
+.\" (C) Copyright 1999-2000 David A. Wheeler (dwheeler@dwheeler.com)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" Fragments of this document are directly derived from IETF standards.
+.\" For those fragments which are directly derived from such standards,
+.\" the following notice applies, which is the standard copyright and
+.\" rights announcement of The Internet Society:
+.\"
+.\" Copyright (C) The Internet Society (1998).  All Rights Reserved.
+.\" This document and translations of it may be copied and furnished to
+.\" others, and derivative works that comment on or otherwise explain it
+.\" or assist in its implementation may be prepared, copied, published
+.\" and distributed, in whole or in part, without restriction of any
+.\" kind, provided that the above copyright notice and this paragraph are
+.\" included on all such copies and derivative works.  However, this
+.\" document itself may not be modified in any way, such as by removing
+.\" the copyright notice or references to the Internet Society or other
+.\" Internet organizations, except as needed for the purpose of
+.\" developing Internet standards in which case the procedures for
+.\" copyrights defined in the Internet Standards process must be
+.\" followed, or as required to translate it into languages other than English.
+.\"
+.\" Modified Fri Jul 25 23:00:00 1999 by David A. Wheeler (dwheeler@dwheeler.com)
+.\" Modified Fri Aug 21 23:00:00 1999 by David A. Wheeler (dwheeler@dwheeler.com)
+.\" Modified Tue Mar 14 2000 by David A. Wheeler (dwheeler@dwheeler.com)
+.\"
+.TH uri 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+uri, url, urn \- uniform resource identifier (URI), including a URL or URN
+.SH SYNOPSIS
+.SY "\fIURI\fP \fR=\fP"
+.RI [\~ absoluteURI
+|
+.IR relativeURI \~]
+.RB [\~\[dq] # \[dq]\~\c
+.IR fragment \~]
+.YS
+.P
+.SY "\fIabsoluteURI\fP \fR=\fP"
+.I scheme\~\c
+.RB \[dq] : \[dq]
+.RI (\~ hierarchical_part
+|
+.IR opaque_part \~)
+.YS
+.P
+.SY "\fIrelativeURI\fP \fR=\fP"
+.RI (\~ net_path
+|
+.I absolute_path
+|
+.IR relative_path \~)
+.RB [\~\[dq] ? \[dq]\~\c
+.IR query \~]
+.YS
+.P
+.SY "\fIscheme\fP \fR=\fP"
+.RB \[dq] http \[dq]
+|
+.RB \[dq] ftp \[dq]
+|
+.RB \[dq] gopher \[dq]
+|
+.RB \[dq] mailto \[dq]
+|
+.RB \[dq] news \[dq]
+|
+.RB \[dq] telnet \[dq]
+|
+.RB \[dq] file \[dq]
+|
+.RB \[dq] ftp \[dq]
+|
+.RB \[dq] man \[dq]
+|
+.RB \[dq] info \[dq]
+|
+.RB \[dq] whatis \[dq]
+|
+.RB \[dq] ldap \[dq]
+|
+.RB \[dq] wais \[dq]
+| \&...
+.YS
+.P
+.SY "\fIhierarchical_part\fP \fR=\fP"
+.RI (\~ net_path
+|
+.IR absolute_path \~)
+.RB [\~\[dq] ? \[dq]\~\c
+.IR query \~]
+.YS
+.P
+.SY "\fInet_path\fP \fR=\fP"
+.RB \[dq] // \[dq]\~\c
+.I authority
+.RI [\~ absolute_path \~]
+.YS
+.P
+.SY "\fIabsolute_path\fP \fR=\fP"
+.RB \[dq] / \[dq]\~\c
+.I path_segments
+.YS
+.P
+.SY "\fIrelative_path\fP \fR=\fP"
+.I relative_segment
+.RI [\~ absolute_path \~]
+.YS
+.SH DESCRIPTION
+A Uniform Resource Identifier (URI) is a short string of characters
+identifying an abstract or physical resource (for example, a web page).
+A Uniform Resource Locator (URL) is a URI
+that identifies a resource through its primary access
+mechanism (e.g., its network "location"), rather than
+by name or some other attribute of that resource.
+A Uniform Resource Name (URN) is a URI
+that must remain globally unique and persistent even when
+the resource ceases to exist or becomes unavailable.
+.P
+URIs are the standard way to name hypertext link destinations
+for tools such as web browsers.
+The string "http://www.kernel.org" is a URL (and thus it
+is also a URI).
+Many people use the term URL loosely as a synonym for URI
+(though technically URLs are a subset of URIs).
+.P
+URIs can be absolute or relative.
+An absolute identifier refers to a resource independent of
+context, while a relative
+identifier refers to a resource by describing the difference
+from the current context.
+Within a relative path reference, the complete path segments "." and
+".." have special meanings: "the current hierarchy level" and "the
+level above this hierarchy level", respectively, just like they do in
+UNIX-like systems.
+A path segment which contains a colon
+character can't be used as the first segment of a relative URI path
+(e.g., "this:that"), because it would be mistaken for a scheme name;
+precede such segments with ./ (e.g., "./this:that").
+Note that descendants of MS-DOS (e.g., Microsoft Windows) replace
+devicename colons with the vertical bar ("|") in URIs, so "C:" becomes "C|".
+.P
+A fragment identifier,
+if included,
+refers to a particular named portion (fragment) of a resource;
+text after a \[aq]#\[aq] identifies the fragment.
+A URI beginning with \[aq]#\[aq]
+refers to that fragment in the current resource.
+.SS Usage
+There are many different URI schemes, each with specific
+additional rules and meanings, but they are intentionally made to be
+as similar as possible.
+For example, many URL schemes
+permit the authority to be the following format, called here an
+.I ip_server
+(square brackets show what's optional):
+.P
+.IR "ip_server = " [ user " [ : " password " ] @ ] " host " [ : " port ]
+.P
+This format allows you to optionally insert a username,
+a user plus password, and/or a port number.
+The
+.I host
+is the name of the host computer, either its name as determined by DNS
+or an IP address (numbers separated by periods).
+Thus the URI
+<http://fred:fredpassword@example.com:8080/>
+logs into a web server on host example.com
+as fred (using fredpassword) using port 8080.
+Avoid including a password in a URI if possible because of the many
+security risks of having a password written down.
+If the URL supplies a username but no password, and the remote
+server requests a password, the program interpreting the URL
+should request one from the user.
+.P
+Here are some of the most common schemes in use on UNIX-like systems
+that are understood by many tools.
+Note that many tools using URIs also have internal schemes or specialized
+schemes; see those tools' documentation for information on those schemes.
+.P
+.B "http \- Web (HTTP) server"
+.P
+.RI http:// ip_server / path
+.br
+.RI http:// ip_server / path ? query
+.P
+This is a URL accessing a web (HTTP) server.
+The default port is 80.
+If the path refers to a directory, the web server will choose what
+to return; usually if there is a file named "index.html" or "index.htm"
+its content is returned, otherwise, a list of the files in the current
+directory (with appropriate links) is generated and returned.
+An example is <http://lwn.net>.
+.P
+A query can be given in the archaic "isindex" format, consisting of a
+word or phrase and not including an equal sign (=).
+A query can also be in the longer "GET" format, which has one or more
+query entries of the form
+.IR key = value
+separated by the ampersand character (&).
+Note that
+.I key
+can be repeated more than once, though it's up to the web server
+and its application programs to determine if there's any meaning to that.
+There is an unfortunate interaction with HTML/XML/SGML and
+the GET query format; when such URIs with more than one key
+are embedded in SGML/XML documents (including HTML), the ampersand
+(&) has to be rewritten as &amp;.
+Note that not all queries use this format; larger forms
+may be too long to store as a URI, so they use a different
+interaction mechanism (called POST) which does
+not include the data in the URI.
+See the Common Gateway Interface specification at
+.UR http://www.w3.org\:/CGI
+.UE
+for more information.
+.P
+.B "ftp \- File Transfer Protocol (FTP)"
+.P
+.RI ftp:// ip_server / path
+.P
+This is a URL accessing a file through the file transfer protocol (FTP).
+The default port (for control) is 21.
+If no username is included, the username "anonymous" is supplied, and
+in that case many clients provide as the password the requestor's
+Internet email address.
+An example is
+<ftp://ftp.is.co.za/rfc/rfc1808.txt>.
+.P
+.B "gopher \- Gopher server"
+.P
+.RI gopher:// ip_server / "gophertype selector"
+.br
+.RI gopher:// ip_server / "gophertype selector" %09 search
+.br
+.RI gopher:// ip_server / "gophertype selector" %09 search %09 gopher+_string
+.br
+.P
+The default gopher port is 70.
+.I gophertype
+is a single-character field to denote the
+Gopher type of the resource to
+which the URL refers.
+The entire path may also be empty, in
+which case the delimiting "/" is also optional and the gophertype
+defaults to "1".
+.P
+.I selector
+is the Gopher selector string.
+In the Gopher protocol,
+Gopher selector strings are a sequence of octets which may contain
+any octets except 09 hexadecimal (US-ASCII HT or tab), 0A hexadecimal
+(US-ASCII character LF), and 0D (US-ASCII character CR).
+.P
+.B "mailto \- Email address"
+.P
+.RI mailto: email-address
+.P
+This is an email address, usually of the form
+.IR name @ hostname .
+See
+.BR mailaddr (7)
+for more information on the correct format of an email address.
+Note that any % character must be rewritten as %25.
+An example is <mailto:dwheeler@dwheeler.com>.
+.P
+.B "news \- Newsgroup or News message"
+.P
+.RI news: newsgroup-name
+.br
+.RI news: message-id
+.P
+A
+.I newsgroup-name
+is a period-delimited hierarchical name, such as
+"comp.infosystems.www.misc".
+If <newsgroup-name> is "*" (as in <news:*>), it is used to refer
+to "all available news groups".
+An example is <news:comp.lang.ada>.
+.P
+A
+.I message-id
+corresponds to the Message-ID of
+.UR http://www.ietf.org\:/rfc\:/rfc1036.txt
+IETF RFC\ 1036,
+.UE
+without the enclosing "<"
+and ">"; it takes the form
+.IR unique @ full_domain_name .
+A message identifier may be distinguished from a news group name by the
+presence of the "@" character.
+.P
+.B "telnet \- Telnet login"
+.P
+.RI telnet:// ip_server /
+.P
+The Telnet URL scheme is used to designate interactive text services that
+may be accessed by the Telnet protocol.
+The final "/" character may be omitted.
+The default port is 23.
+An example is <telnet://melvyl.ucop.edu/>.
+.P
+.B "file \- Normal file"
+.P
+.RI file:// ip_server / path_segments
+.br
+.RI file: path_segments
+.P
+This represents a file or directory accessible locally.
+As a special case,
+.I ip_server
+can be the string "localhost" or the empty
+string; this is interpreted as "the machine from which the URL is
+being interpreted".
+If the path is to a directory, the viewer should display the
+directory's contents with links to each containee;
+not all viewers currently do this.
+KDE supports generated files through the URL <file:/cgi-bin>.
+If the given file isn't found, browser writers may want to try to expand
+the filename via filename globbing
+(see
+.BR glob (7)
+and
+.BR glob (3)).
+.P
+The second format (e.g., <file:/etc/passwd>)
+is a correct format for referring to
+a local file.
+However, older standards did not permit this format,
+and some programs don't recognize this as a URI.
+A more portable syntax is to use an empty string as the server name,
+for example,
+<file:///etc/passwd>; this form does the same thing
+and is easily recognized by pattern matchers and older programs as a URI.
+Note that if you really mean to say "start from the current location", don't
+specify the scheme at all; use a relative address like <../test.txt>,
+which has the side-effect of being scheme-independent.
+An example of this scheme is <file:///etc/passwd>.
+.P
+.B "man \- Man page documentation"
+.P
+.RI man: command-name
+.br
+.RI man: command-name ( section )
+.P
+This refers to local online manual (man) reference pages.
+The command name can optionally be followed by a
+parenthesis and section number; see
+.BR man (7)
+for more information on the meaning of the section numbers.
+This URI scheme is unique to UNIX-like systems (such as Linux)
+and is not currently registered by the IETF.
+An example is <man:ls(1)>.
+.P
+.B "info \- Info page documentation"
+.P
+.RI info: virtual-filename
+.br
+.RI info: virtual-filename # nodename
+.br
+.RI info:( virtual-filename )
+.br
+.RI info:( virtual-filename ) nodename
+.P
+This scheme refers to online info reference pages (generated from
+texinfo files),
+a documentation format used by programs such as the GNU tools.
+This URI scheme is unique to UNIX-like systems (such as Linux)
+and is not currently registered by the IETF.
+As of this writing, GNOME and KDE differ in their URI syntax
+and do not accept the other's syntax.
+The first two formats are the GNOME format; in nodenames all spaces
+are written as underscores.
+The second two formats are the KDE format;
+spaces in nodenames must be written as spaces, even though this
+is forbidden by the URI standards.
+It's hoped that in the future most tools will understand all of these
+formats and will always accept underscores for spaces in nodenames.
+In both GNOME and KDE, if the form without the nodename is used the
+nodename is assumed to be "Top".
+Examples of the GNOME format are <info:gcc> and <info:gcc#G++_and_GCC>.
+Examples of the KDE format are <info:(gcc)> and <info:(gcc)G++ and GCC>.
+.P
+.B "whatis \- Documentation search"
+.P
+.RI whatis: string
+.P
+This scheme searches the database of short (one-line) descriptions of
+commands and returns a list of descriptions containing that string.
+Only complete word matches are returned.
+See
+.BR whatis (1).
+This URI scheme is unique to UNIX-like systems (such as Linux)
+and is not currently registered by the IETF.
+.P
+.B "ghelp \- GNOME help documentation"
+.P
+.RI ghelp: name-of-application
+.P
+This loads GNOME help for the given application.
+Note that not much documentation currently exists in this format.
+.P
+.B "ldap \- Lightweight Directory Access Protocol"
+.P
+.RI ldap:// hostport
+.br
+.RI ldap:// hostport /
+.br
+.RI ldap:// hostport / dn
+.br
+.RI ldap:// hostport / dn ? attributes
+.br
+.RI ldap:// hostport / dn ? attributes ? scope
+.br
+.RI ldap:// hostport / dn ? attributes ? scope ? filter
+.br
+.RI ldap:// hostport / dn ? attributes ? scope ? filter ? extensions
+.P
+This scheme supports queries to the
+Lightweight Directory Access Protocol (LDAP), a protocol for querying
+a set of servers for hierarchically organized information
+(such as people and computing resources).
+See
+.UR http://www.ietf.org\:/rfc\:/rfc2255.txt
+RFC\ 2255
+.UE
+for more information on the LDAP URL scheme.
+The components of this URL are:
+.TP
+hostport
+the LDAP server to query, written as a hostname optionally followed by
+a colon and the port number.
+The default LDAP port is TCP port 389.
+If empty, the client determines which the LDAP server to use.
+.TP
+dn
+the LDAP Distinguished Name, which identifies
+the base object of the LDAP search (see
+.UR http://www.ietf.org\:/rfc\:/rfc2253.txt
+RFC\ 2253
+.UE
+section 3).
+.TP
+attributes
+a comma-separated list of attributes to be returned;
+see RFC\ 2251 section 4.1.5.
+If omitted, all attributes should be returned.
+.TP
+scope
+specifies the scope of the search, which can be one of
+"base" (for a base object search), "one" (for a one-level search),
+or "sub" (for a subtree search).
+If scope is omitted, "base" is assumed.
+.TP
+filter
+specifies the search filter (subset of entries
+to return).
+If omitted, all entries should be returned.
+See
+.UR http://www.ietf.org\:/rfc\:/rfc2254.txt
+RFC\ 2254
+.UE
+section 4.
+.TP
+extensions
+a comma-separated list of type=value
+pairs, where the =value portion may be omitted for options not
+requiring it.
+An extension prefixed with a \[aq]!\[aq] is critical
+(must be supported to be valid), otherwise it is noncritical (optional).
+.P
+LDAP queries are easiest to explain by example.
+Here's a query that asks ldap.itd.umich.edu for information about
+the University of Michigan in the U.S.:
+.P
+.nf
+ldap://ldap.itd.umich.edu/o=University%20of%20Michigan,c=US
+.fi
+.P
+To just get its postal address attribute, request:
+.P
+.nf
+ldap://ldap.itd.umich.edu/o=University%20of%20Michigan,c=US?postalAddress
+.fi
+.P
+To ask a host.com at port 6666 for information about the person
+with common name (cn) "Babs Jensen" at University of Michigan, request:
+.P
+.nf
+ldap://host.com:6666/o=University%20of%20Michigan,c=US??sub?(cn=Babs%20Jensen)
+.fi
+.P
+.B "wais \- Wide Area Information Servers"
+.P
+.RI wais:// hostport / database
+.br
+.RI wais:// hostport / database ? search
+.br
+.RI wais:// hostport / database / wtype / wpath
+.P
+This scheme designates a WAIS database, search, or document
+(see
+.UR http://www.ietf.org\:/rfc\:/rfc1625.txt
+IETF RFC\ 1625
+.UE
+for more information on WAIS).
+Hostport is the hostname, optionally followed by a colon and port number
+(the default port number is 210).
+.P
+The first form designates a WAIS database for searching.
+The second form designates a particular search of the WAIS database
+.IR database .
+The third form designates a particular document within a WAIS
+database to be retrieved.
+.I wtype
+is the WAIS designation of the type of the object and
+.I wpath
+is the WAIS document-id.
+.P
+.B "other schemes"
+.P
+There are many other URI schemes.
+Most tools that accept URIs support a set of internal URIs
+(e.g., Mozilla has the about: scheme for internal information,
+and the GNOME help browser has the toc: scheme for various starting
+locations).
+There are many schemes that have been defined but are not as widely
+used at the current time
+(e.g., prospero).
+The nntp: scheme is deprecated in favor of the news: scheme.
+URNs are to be supported by the urn: scheme, with a hierarchical name space
+(e.g., urn:ietf:... would identify IETF documents); at this time
+URNs are not widely implemented.
+Not all tools support all schemes.
+.SS Character encoding
+URIs use a limited number of characters so that they can be
+typed in and used in a variety of situations.
+.P
+The following characters are reserved, that is, they may appear in a
+URI but their use is limited to their reserved purpose
+(conflicting data must be escaped before forming the URI):
+.IP
+.in +4n
+.EX
+; / ? : @ & = + $ ,
+.EE
+.in
+.P
+Unreserved characters may be included in a URI.
+Unreserved characters
+include uppercase and lowercase Latin letters,
+decimal digits, and the following
+limited set of punctuation marks and symbols:
+.IP
+.in +4n
+.EX
+\- _ . ! \[ti] * ' ( )
+.EE
+.in
+.P
+All other characters must be escaped.
+An escaped octet is encoded as a character triplet, consisting of the
+percent character "%" followed by the two hexadecimal digits
+representing the octet code (you can use uppercase or lowercase letters
+for the hexadecimal digits).
+For example, a blank space must be escaped
+as "%20", a tab character as "%09", and the "&" as "%26".
+Because the percent "%" character always has the reserved purpose of
+being the escape indicator, it must be escaped as "%25".
+It is common practice to escape space characters as the plus symbol (+)
+in query text; this practice isn't uniformly defined
+in the relevant RFCs (which recommend %20 instead) but any tool accepting
+URIs with query text should be prepared for them.
+A URI is always shown in its "escaped" form.
+.P
+Unreserved characters can be escaped without changing the semantics
+of the URI, but this should not be done unless the URI is being used
+in a context that does not allow the unescaped character to appear.
+For example, "%7e" is sometimes used instead of "\[ti]" in an HTTP URL
+path, but the two are equivalent for an HTTP URL.
+.P
+For URIs which must handle characters outside the US ASCII character set,
+the HTML 4.01 specification (section B.2) and
+IETF RFC\~3986 (last paragraph of section 2.5)
+recommend the following approach:
+.IP (1) 5
+translate the character sequences into UTF-8 (IETF RFC\~3629)\[em]see
+.BR utf\-8 (7)\[em]and
+then
+.IP (2)
+use the URI escaping mechanism, that is,
+use the %HH encoding for unsafe octets.
+.SS Writing a URI
+When written, URIs should be placed inside double quotes
+(e.g., "http://www.kernel.org"),
+enclosed in angle brackets (e.g., <http://lwn.net>),
+or placed on a line by themselves.
+A warning for those who use double-quotes:
+.B never
+move extraneous punctuation (such as the period ending a sentence or the
+comma in a list)
+inside a URI, since this will change the value of the URI.
+Instead, use angle brackets instead, or
+switch to a quoting system that never includes extraneous characters
+inside quotation marks.
+This latter system, called the 'new' or 'logical' quoting system by
+"Hart's Rules" and the "Oxford Dictionary for Writers and Editors",
+is preferred practice in Great Britain and in various European languages.
+Older documents suggested inserting the prefix "URL:"
+just before the URI, but this form has never caught on.
+.P
+The URI syntax was designed to be unambiguous.
+However, as URIs have become commonplace, traditional media
+(television, radio, newspapers, billboards, etc.) have increasingly
+used abbreviated URI references consisting of
+only the authority and path portions of the identified resource
+(e.g., <www.w3.org/Addressing>).
+Such references are primarily
+intended for human interpretation rather than machine, with the
+assumption that context-based heuristics are sufficient to complete
+the URI (e.g., hostnames beginning with "www" are likely to have
+a URI prefix of "http://" and hostnames beginning with "ftp" likely
+to have a prefix of "ftp://").
+Many client implementations heuristically resolve these references.
+Such heuristics may
+change over time, particularly when new schemes are introduced.
+Since an abbreviated URI has the same syntax as a relative URL path,
+abbreviated URI references cannot be used where relative URIs are
+permitted, and can be used only when there is no defined base
+(such as in dialog boxes).
+Don't use abbreviated URIs as hypertext links inside a document;
+use the standard format as described here.
+.SH STANDARDS
+.UR http://www.ietf.org\:/rfc\:/rfc2396.txt
+(IETF RFC\ 2396)
+.UE ,
+.UR http://www.w3.org\:/TR\:/REC\-html40
+(HTML 4.0)
+.UE .
+.SH NOTES
+Any tool accepting URIs (e.g., a web browser) on a Linux system should
+be able to handle (directly or indirectly) all of the
+schemes described here, including the man: and info: schemes.
+Handling them by invoking some other program is
+fine and in fact encouraged.
+.P
+Technically the fragment isn't part of the URI.
+.P
+For information on how to embed URIs (including URLs) in a data format,
+see documentation on that format.
+HTML uses the format <A HREF="\fIuri\fP">
+.I text
+</A>.
+Texinfo files use the format @uref{\fIuri\fP}.
+Man and mdoc have the recently added UR macro, or just include the
+URI in the text (viewers should be able to detect :// as part of a URI).
+.P
+The GNOME and KDE desktop environments currently vary in the URIs
+they accept, in particular in their respective help browsers.
+To list man pages, GNOME uses <toc:man> while KDE uses <man:(index)>, and
+to list info pages, GNOME uses <toc:info> while KDE uses <info:(dir)>
+(the author of this man page prefers the KDE approach here, though a more
+regular format would be even better).
+In general, KDE uses <file:/cgi-bin/> as a prefix to a set of generated
+files.
+KDE prefers documentation in HTML, accessed via the
+<file:/cgi-bin/helpindex>.
+GNOME prefers the ghelp scheme to store and find documentation.
+Neither browser handles file: references to directories at the time
+of this writing, making it difficult to refer to an entire directory with
+a browsable URI.
+As noted above, these environments differ in how they handle the
+info: scheme, probably the most important variation.
+It is expected that GNOME and KDE
+will converge to common URI formats, and a future
+version of this man page will describe the converged result.
+Efforts to aid this convergence are encouraged.
+.SS Security
+A URI does not in itself pose a security threat.
+There is no general guarantee that a URL, which at one time
+located a given resource, will continue to do so.
+Nor is there any
+guarantee that a URL will not locate a different resource at some
+later point in time; such a guarantee can be
+obtained only from the person(s) controlling that namespace and the
+resource in question.
+.P
+It is sometimes possible to construct a URL such that an attempt to
+perform a seemingly harmless operation, such as the
+retrieval of an entity associated with the resource, will in fact
+cause a possibly damaging remote operation to occur.
+The unsafe URL
+is typically constructed by specifying a port number other than that
+reserved for the network protocol in question.
+The client unwittingly contacts a site that is in fact
+running a different protocol.
+The content of the URL contains instructions that, when
+interpreted according to this other protocol, cause an unexpected
+operation.
+An example has been the use of a gopher URL to cause an
+unintended or impersonating message to be sent via a SMTP server.
+.P
+Caution should be used when using any URL that specifies a port
+number other than the default for the protocol, especially when it is
+a number within the reserved space.
+.P
+Care should be taken when a URI contains escaped delimiters for a
+given protocol (for example, CR and LF characters for telnet
+protocols) that these are not unescaped before transmission.
+This might violate the protocol, but avoids the potential for such
+characters to be used to simulate an extra operation or parameter in
+that protocol, which might lead to an unexpected and possibly harmful
+remote operation to be performed.
+.P
+It is clearly unwise to use a URI that contains a password which is
+intended to be secret.
+In particular, the use of a password within
+the "userinfo" component of a URI is strongly recommended against except
+in those rare cases where the "password" parameter is intended to be public.
+.SH BUGS
+Documentation may be placed in a variety of locations, so there
+currently isn't a good URI scheme for general online documentation
+in arbitrary formats.
+References of the form
+<file:///usr/doc/ZZZ> don't work because different distributions and
+local installation requirements may place the files in different
+directories
+(it may be in /usr/doc, or /usr/local/doc, or /usr/share,
+or somewhere else).
+Also, the directory ZZZ usually changes when a version changes
+(though filename globbing could partially overcome this).
+Finally, using the file: scheme doesn't easily support people
+who dynamically load documentation from the Internet (instead of
+loading the files onto a local filesystem).
+A future URI scheme may be added (e.g., "userdoc:") to permit
+programs to include cross-references to more detailed documentation
+without having to know the exact location of that documentation.
+Alternatively, a future version of the filesystem specification may
+specify file locations sufficiently so that the file: scheme will
+be able to locate documentation.
+.P
+Many programs and file formats don't include a way to incorporate
+or implement links using URIs.
+.P
+Many programs can't handle all of these different URI formats; there
+should be a standard mechanism to load an arbitrary URI that automatically
+detects the users' environment (e.g., text or graphics,
+desktop environment, local user preferences, and currently executing
+tools) and invokes the right tool for any URI.
+.\" .SH AUTHOR
+.\" David A. Wheeler (dwheeler@dwheeler.com) wrote this man page.
+.SH SEE ALSO
+.BR lynx (1),
+.BR man2html (1),
+.BR mailaddr (7),
+.BR utf\-8 (7)
+.P
+.UR http://www.ietf.org\:/rfc\:/rfc2255.txt
+IETF RFC\ 2255
+.UE
diff --git a/man/man7/url.7 b/man/man7/url.7
new file mode 100644
index 000000000..079fb5e7b
--- /dev/null
+++ b/man/man7/url.7
@@ -0,0 +1 @@
+.so man7/uri.7
diff --git a/man/man7/urn.7 b/man/man7/urn.7
new file mode 100644
index 000000000..079fb5e7b
--- /dev/null
+++ b/man/man7/urn.7
@@ -0,0 +1 @@
+.so man7/uri.7
diff --git a/man/man7/user-keyring.7 b/man/man7/user-keyring.7
new file mode 100644
index 000000000..77c4bb0a9
--- /dev/null
+++ b/man/man7/user-keyring.7
@@ -0,0 +1,81 @@
+.\" Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH user-keyring 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+user-keyring \- per-user keyring
+.SH DESCRIPTION
+The user keyring is a keyring used to anchor keys on behalf of a user.
+Each UID the kernel deals with has its own user keyring that
+is shared by all processes with that UID.
+The user keyring has a name (description) of the form
+.I _uid.<UID>
+where
+.I <UID>
+is the user ID of the corresponding user.
+.P
+The user keyring is associated with the record that the kernel maintains
+for the UID.
+It comes into existence upon the first attempt to access either the
+user keyring, the
+.BR user\-session\-keyring (7),
+or the
+.BR session\-keyring (7).
+The keyring remains pinned in existence so long as there are processes
+running with that real UID or files opened by those processes remain open.
+(The keyring can also be pinned indefinitely by linking it
+into another keyring.)
+.P
+Typically, the user keyring is created by
+.BR pam_keyinit (8)
+when a user logs in.
+.P
+The user keyring is not searched by default by
+.BR request_key (2).
+When
+.BR pam_keyinit (8)
+creates a session keyring, it adds to it a link to the user
+keyring so that the user keyring will be searched when the session keyring is.
+.P
+A special serial number value,
+.BR KEY_SPEC_USER_KEYRING ,
+is defined that can be used in lieu of the actual serial number of
+the calling process's user keyring.
+.P
+From the
+.BR keyctl (1)
+utility, '\fB@u\fP' can be used instead of a numeric key ID in
+much the same way.
+.P
+User keyrings are independent of
+.BR clone (2),
+.BR fork (2),
+.BR vfork (2),
+.BR execve (2),
+and
+.BR _exit (2)
+excepting that the keyring is destroyed when the UID record is destroyed when
+the last process pinning it exits.
+.P
+If it is necessary for a key associated with a user to exist beyond the UID
+record being garbage collected\[em]for example, for use by a
+.BR cron (8)
+script\[em]then the
+.BR persistent\-keyring (7)
+should be used instead.
+.P
+If a user keyring does not exist when it is accessed, it will be created.
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR keyctl (3),
+.BR keyrings (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-session\-keyring (7),
+.BR pam_keyinit (8)
diff --git a/man/man7/user-session-keyring.7 b/man/man7/user-session-keyring.7
new file mode 100644
index 000000000..d7b633299
--- /dev/null
+++ b/man/man7/user-session-keyring.7
@@ -0,0 +1,92 @@
+.\" Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH user-session-keyring 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+user-session-keyring \- per-user default session keyring
+.SH DESCRIPTION
+The user session keyring is a keyring used to anchor keys on behalf of a user.
+Each UID the kernel deals with has its own user session keyring that
+is shared by all processes with that UID.
+The user session keyring has a name (description) of the form
+.I _uid_ses.<UID>
+where
+.I <UID>
+is the user ID of the corresponding user.
+.P
+The user session keyring is associated with the record that
+the kernel maintains for the UID.
+It comes into existence upon the first attempt to access either the
+user session keyring, the
+.BR user\-keyring (7),
+or the
+.BR session\-keyring (7).
+.\" Davis Howells: the user and user-session keyrings are managed as a pair.
+The keyring remains pinned in existence so long as there are processes
+running with that real UID or files opened by those processes remain open.
+(The keyring can also be pinned indefinitely by linking it
+into another keyring.)
+.P
+The user session keyring is created on demand when a thread requests it
+or when a thread asks for its
+.BR session\-keyring (7)
+and that keyring doesn't exist.
+In the latter case, a user session keyring will be created and,
+if the session keyring wasn't to be created,
+the user session keyring will be set as the process's actual session keyring.
+.P
+The user session keyring is searched by
+.BR request_key (2)
+if the actual session keyring does not exist and is ignored otherwise.
+.P
+A special serial number value,
+.BR KEY_SPEC_USER_SESSION_KEYRING ,
+is defined
+that can be used in lieu of the actual serial number of
+the calling process's user session keyring.
+.P
+From the
+.BR keyctl (1)
+utility, '\fB@us\fP' can be used instead of a numeric key ID in
+much the same way.
+.P
+User session keyrings are independent of
+.BR clone (2),
+.BR fork (2),
+.BR vfork (2),
+.BR execve (2),
+and
+.BR _exit (2)
+excepting that the keyring is destroyed when the UID record is destroyed
+when the last process pinning it exits.
+.P
+If a user session keyring does not exist when it is accessed,
+it will be created.
+.P
+Rather than relying on the user session keyring,
+it is strongly recommended\[em]especially if the process
+is running as root\[em]that a
+.BR session\-keyring (7)
+be set explicitly, for example by
+.BR pam_keyinit (8).
+.SH NOTES
+The user session keyring was added to support situations where
+a process doesn't have a session keyring,
+perhaps because it was created via a pathway that didn't involve PAM
+(e.g., perhaps it was a daemon started by
+.BR inetd (8)).
+In such a scenario, the user session keyring acts as a substitute for the
+.BR session\-keyring (7).
+.SH SEE ALSO
+.ad l
+.nh
+.BR keyctl (1),
+.BR keyctl (3),
+.BR keyrings (7),
+.BR persistent\-keyring (7),
+.BR process\-keyring (7),
+.BR session\-keyring (7),
+.BR thread\-keyring (7),
+.BR user\-keyring (7)
diff --git a/man/man7/user_namespaces.7 b/man/man7/user_namespaces.7
new file mode 100644
index 000000000..ddeb669c3
--- /dev/null
+++ b/man/man7/user_namespaces.7
@@ -0,0 +1,1469 @@
+.\" Copyright (c) 2013, 2014 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\" and Copyright (c) 2012, 2014 by Eric W. Biederman <ebiederm@xmission.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH user_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+user_namespaces \- overview of Linux user namespaces
+.SH DESCRIPTION
+For an overview of namespaces, see
+.BR namespaces (7).
+.P
+User namespaces isolate security-related identifiers and attributes,
+in particular,
+user IDs and group IDs (see
+.BR credentials (7)),
+the root directory,
+keys (see
+.BR keyrings (7)),
+.\" FIXME: This page says very little about the interaction
+.\" of user namespaces and keys. Add something on this topic.
+and capabilities (see
+.BR capabilities (7)).
+A process's user and group IDs can be different
+inside and outside a user namespace.
+In particular,
+a process can have a normal unprivileged user ID outside a user namespace
+while at the same time having a user ID of 0 inside the namespace;
+in other words,
+the process has full privileges for operations inside the user namespace,
+but is unprivileged for operations outside the namespace.
+.\"
+.\" ============================================================
+.\"
+.SS Nested namespaces, namespace membership
+User namespaces can be nested;
+that is, each user namespace\[em]except the initial ("root")
+namespace\[em]has a parent user namespace,
+and can have zero or more child user namespaces.
+The parent user namespace is the user namespace
+of the process that creates the user namespace via a call to
+.BR unshare (2)
+or
+.BR clone (2)
+with the
+.B CLONE_NEWUSER
+flag.
+.P
+The kernel imposes (since Linux 3.11) a limit of 32 nested levels of
+.\" commit 8742f229b635bf1c1c84a3dfe5e47c814c20b5c8
+user namespaces.
+.\" FIXME Explain the rationale for this limit. (What is the rationale?)
+Calls to
+.BR unshare (2)
+or
+.BR clone (2)
+that would cause this limit to be exceeded fail with the error
+.BR EUSERS .
+.P
+Each process is a member of exactly one user namespace.
+A process created via
+.BR fork (2)
+or
+.BR clone (2)
+without the
+.B CLONE_NEWUSER
+flag is a member of the same user namespace as its parent.
+A single-threaded process can join another user namespace with
+.BR setns (2)
+if it has the
+.B CAP_SYS_ADMIN
+in that namespace;
+upon doing so, it gains a full set of capabilities in that namespace.
+.P
+A call to
+.BR clone (2)
+or
+.BR unshare (2)
+with the
+.B CLONE_NEWUSER
+flag makes the new child process (for
+.BR clone (2))
+or the caller (for
+.BR unshare (2))
+a member of the new user namespace created by the call.
+.P
+The
+.B NS_GET_PARENT
+.BR ioctl (2)
+operation can be used to discover the parental relationship
+between user namespaces; see
+.BR ioctl_ns (2).
+.P
+A task that changes one of its effective IDs
+will have its dumpability reset to the value in
+.IR /proc/sys/fs/suid_dumpable .
+This may affect the ownership of proc files of child processes
+and may thus cause the parent to lack the permissions
+to write to mapping files of child processes running in a new user namespace.
+In such cases making the parent process dumpable, using
+.B PR_SET_DUMPABLE
+in a call to
+.BR prctl (2),
+before creating a child process in a new user namespace
+may rectify this problem.
+See
+.BR prctl (2)
+and
+.BR proc (5)
+for details on how ownership is affected.
+.\"
+.\" ============================================================
+.\"
+.SS Capabilities
+The child process created by
+.BR clone (2)
+with the
+.B CLONE_NEWUSER
+flag starts out with a complete set
+of capabilities in the new user namespace.
+Likewise, a process that creates a new user namespace using
+.BR unshare (2)
+or joins an existing user namespace using
+.BR setns (2)
+gains a full set of capabilities in that namespace.
+On the other hand,
+that process has no capabilities in the parent (in the case of
+.BR clone (2))
+or previous (in the case of
+.BR unshare (2)
+and
+.BR setns (2))
+user namespace,
+even if the new namespace is created or joined by the root user
+(i.e., a process with user ID 0 in the root namespace).
+.P
+Note that a call to
+.BR execve (2)
+will cause a process's capabilities to be recalculated in the usual way (see
+.BR capabilities (7)).
+Consequently,
+unless the process has a user ID of 0 within the namespace,
+or the executable file has a nonempty inheritable capabilities mask,
+the process will lose all capabilities.
+See the discussion of user and group ID mappings, below.
+.P
+A call to
+.BR clone (2)
+or
+.BR unshare (2)
+using the
+.B CLONE_NEWUSER
+flag
+or a call to
+.BR setns (2)
+that moves the caller into another user namespace
+sets the "securebits" flags
+(see
+.BR capabilities (7))
+to their default values (all flags disabled) in the child (for
+.BR clone (2))
+or caller (for
+.BR unshare (2)
+or
+.BR setns (2)).
+Note that because the caller no longer has capabilities
+in its original user namespace after a call to
+.BR setns (2),
+it is not possible for a process to reset its "securebits" flags while
+retaining its user namespace membership by using a pair of
+.BR setns (2)
+calls to move to another user namespace and then return to
+its original user namespace.
+.P
+The rules for determining whether or not a process has a capability
+in a particular user namespace are as follows:
+.IP \[bu] 3
+A process has a capability inside a user namespace
+if it is a member of that namespace and
+it has the capability in its effective capability set.
+A process can gain capabilities in its effective capability
+set in various ways.
+For example, it may execute a set-user-ID program or an
+executable with associated file capabilities.
+In addition,
+a process may gain capabilities via the effect of
+.BR clone (2),
+.BR unshare (2),
+or
+.BR setns (2),
+as already described.
+.\" In the 3.8 sources, see security/commoncap.c::cap_capable():
+.IP \[bu]
+If a process has a capability in a user namespace,
+then it has that capability in all child (and further removed descendant)
+namespaces as well.
+.IP \[bu]
+.\" * The owner of the user namespace in the parent of the
+.\" * user namespace has all caps.
+When a user namespace is created, the kernel records the effective
+user ID of the creating process as being the "owner" of the namespace.
+.\" (and likewise associates the effective group ID of the creating process
+.\" with the namespace).
+A process that resides
+in the parent of the user namespace
+.\" See kernel commit 520d9eabce18edfef76a60b7b839d54facafe1f9 for a fix
+.\" on this point
+and whose effective user ID matches the owner of the namespace
+has all capabilities in the namespace.
+.\"     This includes the case where the process executes a set-user-ID
+.\"     program that confers the effective UID of the creator of the namespace.
+By virtue of the previous rule,
+this means that the process has all capabilities in all
+further removed descendant user namespaces as well.
+The
+.B NS_GET_OWNER_UID
+.BR ioctl (2)
+operation can be used to discover the user ID of the owner of the namespace;
+see
+.BR ioctl_ns (2).
+.\"
+.\" ============================================================
+.\"
+.SS Effect of capabilities within a user namespace
+Having a capability inside a user namespace
+permits a process to perform operations (that require privilege)
+only on resources governed by that namespace.
+In other words, having a capability in a user namespace permits a process
+to perform privileged operations on resources that are governed by (nonuser)
+namespaces owned by (associated with) the user namespace
+(see the next subsection).
+.P
+On the other hand, there are many privileged operations that affect
+resources that are not associated with any namespace type,
+for example, changing the system (i.e., calendar) time (governed by
+.BR CAP_SYS_TIME ),
+loading a kernel module (governed by
+.BR CAP_SYS_MODULE ),
+and creating a device (governed by
+.BR CAP_MKNOD ).
+Only a process with privileges in the
+.I initial
+user namespace can perform such operations.
+.P
+Holding
+.B CAP_SYS_ADMIN
+within the user namespace that owns a process's mount namespace
+allows that process to create bind mounts
+and mount the following types of filesystems:
+.\" fs_flags = FS_USERNS_MOUNT in kernel sources
+.P
+.RS 4
+.PD 0
+.IP \[bu] 3
+.I /proc
+(since Linux 3.8)
+.IP \[bu]
+.I /sys
+(since Linux 3.8)
+.IP \[bu]
+.I devpts
+(since Linux 3.9)
+.IP \[bu]
+.BR tmpfs (5)
+(since Linux 3.9)
+.IP \[bu]
+.I ramfs
+(since Linux 3.9)
+.IP \[bu]
+.I mqueue
+(since Linux 3.9)
+.IP \[bu]
+.I bpf
+.\" commit b2197755b2633e164a439682fb05a9b5ea48f706
+(since Linux 4.4)
+.IP \[bu]
+.I overlayfs
+.\" commit 92dbc9dedccb9759c7f9f2f0ae6242396376988f
+.\" commit 4cb2c00c43b3fe88b32f29df4f76da1b92c33224
+(since Linux 5.11)
+.PD
+.RE
+.P
+Holding
+.B CAP_SYS_ADMIN
+within the user namespace that owns a process's cgroup namespace
+allows (since Linux 4.6)
+that process to the mount the cgroup version 2 filesystem and
+cgroup version 1 named hierarchies
+(i.e., cgroup filesystems mounted with the
+.I \[dq]none,name=\[dq]
+option).
+.P
+Holding
+.B CAP_SYS_ADMIN
+within the user namespace that owns a process's PID namespace
+allows (since Linux 3.8)
+that process to mount
+.I /proc
+filesystems.
+.P
+Note, however, that mounting block-based filesystems can be done
+only by a process that holds
+.B CAP_SYS_ADMIN
+in the initial user namespace.
+.\"
+.\" ============================================================
+.\"
+.SS Interaction of user namespaces and other types of namespaces
+Starting in Linux 3.8, unprivileged processes can create user namespaces,
+and the other types of namespaces can be created with just the
+.B CAP_SYS_ADMIN
+capability in the caller's user namespace.
+.P
+When a nonuser namespace is created,
+it is owned by the user namespace in which the creating process
+was a member at the time of the creation of the namespace.
+Privileged operations on resources governed by the nonuser namespace
+require that the process has the necessary capabilities
+in the user namespace that owns the nonuser namespace.
+.P
+If
+.B CLONE_NEWUSER
+is specified along with other
+.B CLONE_NEW*
+flags in a single
+.BR clone (2)
+or
+.BR unshare (2)
+call, the user namespace is guaranteed to be created first,
+giving the child
+.RB ( clone (2))
+or caller
+.RB ( unshare (2))
+privileges over the remaining namespaces created by the call.
+Thus, it is possible for an unprivileged caller to specify this combination
+of flags.
+.P
+When a new namespace (other than a user namespace) is created via
+.BR clone (2)
+or
+.BR unshare (2),
+the kernel records the user namespace of the creating process as the owner of
+the new namespace.
+(This association can't be changed.)
+When a process in the new namespace subsequently performs
+privileged operations that operate on global
+resources isolated by the namespace,
+the permission checks are performed according to the process's capabilities
+in the user namespace that the kernel associated with the new namespace.
+For example, suppose that a process attempts to change the hostname
+.RB ( sethostname (2)),
+a resource governed by the UTS namespace.
+In this case,
+the kernel will determine which user namespace owns
+the process's UTS namespace, and check whether the process has the
+required capability
+.RB ( CAP_SYS_ADMIN )
+in that user namespace.
+.P
+The
+.B NS_GET_USERNS
+.BR ioctl (2)
+operation can be used to discover the user namespace
+that owns a nonuser namespace; see
+.BR ioctl_ns (2).
+.\"
+.\" ============================================================
+.\"
+.SS User and group ID mappings: uid_map and gid_map
+When a user namespace is created,
+it starts out without a mapping of user IDs (group IDs)
+to the parent user namespace.
+The
+.IR /proc/ pid /uid_map
+and
+.IR /proc/ pid /gid_map
+files (available since Linux 3.5)
+.\" commit 22d917d80e842829d0ca0a561967d728eb1d6303
+expose the mappings for user and group IDs
+inside the user namespace for the process
+.IR pid .
+These files can be read to view the mappings in a user namespace and
+written to (once) to define the mappings.
+.P
+The description in the following paragraphs explains the details for
+.IR uid_map ;
+.I gid_map
+is exactly the same,
+but each instance of "user ID" is replaced by "group ID".
+.P
+The
+.I uid_map
+file exposes the mapping of user IDs from the user namespace
+of the process
+.I pid
+to the user namespace of the process that opened
+.I uid_map
+(but see a qualification to this point below).
+In other words, processes that are in different user namespaces
+will potentially see different values when reading from a particular
+.I uid_map
+file, depending on the user ID mappings for the user namespaces
+of the reading processes.
+.P
+Each line in the
+.I uid_map
+file specifies a 1-to-1 mapping of a range of contiguous
+user IDs between two user namespaces.
+(When a user namespace is first created, this file is empty.)
+The specification in each line takes the form of
+three numbers delimited by white space.
+The first two numbers specify the starting user ID in
+each of the two user namespaces.
+The third number specifies the length of the mapped range.
+In detail, the fields are interpreted as follows:
+.IP (1) 5
+The start of the range of user IDs in
+the user namespace of the process
+.IR pid .
+.IP (2)
+The start of the range of user
+IDs to which the user IDs specified by field one map.
+How field two is interpreted depends on whether the process that opened
+.I uid_map
+and the process
+.I pid
+are in the same user namespace, as follows:
+.RS
+.IP (a) 5
+If the two processes are in different user namespaces:
+field two is the start of a range of
+user IDs in the user namespace of the process that opened
+.IR uid_map .
+.IP (b)
+If the two processes are in the same user namespace:
+field two is the start of the range of
+user IDs in the parent user namespace of the process
+.IR pid .
+This case enables the opener of
+.I uid_map
+(the common case here is opening
+.IR /proc/self/uid_map )
+to see the mapping of user IDs into the user namespace of the process
+that created this user namespace.
+.RE
+.IP (3)
+The length of the range of user IDs that is mapped between the two
+user namespaces.
+.P
+System calls that return user IDs (group IDs)\[em]for example,
+.BR getuid (2),
+.BR getgid (2),
+and the credential fields in the structure returned by
+.BR stat (2)\[em]return
+the user ID (group ID) mapped into the caller's user namespace.
+.P
+When a process accesses a file, its user and group IDs
+are mapped into the initial user namespace for the purpose of permission
+checking and assigning IDs when creating a file.
+When a process retrieves file user and group IDs via
+.BR stat (2),
+the IDs are mapped in the opposite direction,
+to produce values relative to the process user and group ID mappings.
+.P
+The initial user namespace has no parent namespace,
+but, for consistency, the kernel provides dummy user and group
+ID mapping files for this namespace.
+Looking at the
+.I uid_map
+file
+.RI ( gid_map
+is the same) from a shell in the initial namespace shows:
+.P
+.in +4n
+.EX
+$ \fBcat /proc/$$/uid_map\fP
+         0          0 4294967295
+.EE
+.in
+.P
+This mapping tells us
+that the range starting at user ID 0 in this namespace
+maps to a range starting at 0 in the (nonexistent) parent namespace,
+and the length of the range is the largest 32-bit unsigned integer.
+This leaves 4294967295 (the 32-bit signed \-1 value) unmapped.
+This is deliberate:
+.I (uid_t)\~\-1
+is used in several interfaces (e.g.,
+.BR setreuid (2))
+as a way to specify "no user ID".
+Leaving
+.I (uid_t)\~\-1
+unmapped and unusable guarantees that there will be no
+confusion when using these interfaces.
+.\"
+.\" ============================================================
+.\"
+.SS Defining user and group ID mappings: writing to uid_map and gid_map
+After the creation of a new user namespace, the
+.I uid_map
+file of
+.I one
+of the processes in the namespace may be written to
+.I once
+to define the mapping of user IDs in the new user namespace.
+An attempt to write more than once to a
+.I uid_map
+file in a user namespace fails with the error
+.BR EPERM .
+Similar rules apply for
+.I gid_map
+files.
+.P
+The lines written to
+.I uid_map
+.RI ( gid_map )
+must conform to the following validity rules:
+.IP \[bu] 3
+The three fields must be valid numbers,
+and the last field must be greater than 0.
+.IP \[bu]
+Lines are terminated by newline characters.
+.IP \[bu]
+There is a limit on the number of lines in the file.
+In Linux 4.14 and earlier, this limit was (arbitrarily)
+.\" 5*12-byte records could fit in a 64B cache line
+set at 5 lines.
+Since Linux 4.15,
+.\" commit 6397fac4915ab3002dc15aae751455da1a852f25
+the limit is 340 lines.
+In addition, the number of bytes written to
+the file must be less than the system page size,
+and the write must be performed at the start of the file (i.e.,
+.BR lseek (2)
+and
+.BR pwrite (2)
+can't be used to write to nonzero offsets in the file).
+.IP \[bu]
+The range of user IDs (group IDs)
+specified in each line cannot overlap with the ranges
+in any other lines.
+In the initial implementation (Linux 3.8), this requirement was
+satisfied by a simplistic implementation that imposed the further
+requirement that
+the values in both field 1 and field 2 of successive lines must be
+in ascending numerical order,
+which prevented some otherwise valid maps from being created.
+Linux 3.9 and later
+.\" commit 0bd14b4fd72afd5df41e9fd59f356740f22fceba
+fix this limitation, allowing any valid set of nonoverlapping maps.
+.IP \[bu]
+At least one line must be written to the file.
+.P
+Writes that violate the above rules fail with the error
+.BR EINVAL .
+.P
+In order for a process to write to the
+.IR /proc/ pid /uid_map
+.RI ( /proc/ pid /gid_map )
+file, all of the following permission requirements must be met:
+.IP \[bu] 3
+The writing process must have the
+.B CAP_SETUID
+.RB ( CAP_SETGID )
+capability in the user namespace of the process
+.IR pid .
+.IP \[bu]
+The writing process must either be in the user namespace of the process
+.I pid
+or be in the parent user namespace of the process
+.IR pid .
+.IP \[bu]
+The mapped user IDs (group IDs) must in turn have a mapping
+in the parent user namespace.
+.IP \[bu]
+If updating
+.IR /proc/ pid /uid_map
+to create a mapping that maps UID 0 in the parent namespace,
+then one of the following must be true:
+.RS
+.IP (a) 5
+if writing process is in the parent user namespace,
+then it must have the
+.B CAP_SETFCAP
+capability in that user namespace; or
+.IP (b)
+if the writing process is in the child user namespace,
+then the process that created the user namespace must have had the
+.B CAP_SETFCAP
+capability when the namespace was created.
+.RE
+.IP
+This rule has been in place since
+.\" commit db2e718a47984b9d71ed890eb2ea36ecf150de18
+Linux 5.12.
+It eliminates an earlier security bug whereby
+a UID 0 process that lacks the
+.B CAP_SETFCAP
+capability,
+which is needed to create a binary with namespaced file capabilities
+(as described in
+.BR capabilities (7)),
+could nevertheless create such a binary,
+by the following steps:
+.RS
+.IP (1) 5
+Create a new user namespace with the identity mapping
+(i.e., UID 0 in the new user namespace maps to UID 0 in the parent namespace),
+so that UID 0 in both namespaces is equivalent to the same root user ID.
+.IP (2)
+Since the child process has the
+.B CAP_SETFCAP
+capability, it could create a binary with namespaced file capabilities
+that would then be effective in the parent user namespace
+(because the root user IDs are the same in the two namespaces).
+.RE
+.IP \[bu]
+One of the following two cases applies:
+.RS
+.IP (a) 5
+.I Either
+the writing process has the
+.B CAP_SETUID
+.RB ( CAP_SETGID )
+capability in the
+.I parent
+user namespace.
+.RS
+.IP \[bu] 3
+No further restrictions apply:
+the process can make mappings to arbitrary user IDs (group IDs)
+in the parent user namespace.
+.RE
+.IP (b)
+.I Or
+otherwise all of the following restrictions apply:
+.RS
+.IP \[bu] 3
+The data written to
+.I uid_map
+.RI ( gid_map )
+must consist of a single line that maps
+the writing process's effective user ID
+(group ID) in the parent user namespace to a user ID (group ID)
+in the user namespace.
+.IP \[bu]
+The writing process must have the same effective user ID as the process
+that created the user namespace.
+.IP \[bu]
+In the case of
+.IR gid_map ,
+use of the
+.BR setgroups (2)
+system call must first be denied by writing
+.RI \[dq] deny \[dq]
+to the
+.IR /proc/ pid /setgroups
+file (see below) before writing to
+.IR gid_map .
+.RE
+.RE
+.P
+Writes that violate the above rules fail with the error
+.BR EPERM .
+.\"
+.\" ============================================================
+.\"
+.SS Project ID mappings: projid_map
+Similarly to user and group ID mappings,
+it is possible to create project ID mappings for a user namespace.
+(Project IDs are used for disk quotas; see
+.BR setquota (8)
+and
+.BR quotactl (2).)
+.P
+Project ID mappings are defined by writing to the
+.IR /proc/ pid /projid_map
+file (present since
+.\" commit f76d207a66c3a53defea67e7d36c3eb1b7d6d61d
+Linux 3.7).
+.P
+The validity rules for writing to the
+.IR /proc/ pid /projid_map
+file are as for writing to the
+.I uid_map
+file; violation of these rules causes
+.BR write (2)
+to fail with the error
+.BR EINVAL .
+.P
+The permission rules for writing to the
+.IR /proc/ pid /projid_map
+file are as follows:
+.IP \[bu] 3
+The writing process must either be in the user namespace of the process
+.I pid
+or be in the parent user namespace of the process
+.IR pid .
+.IP \[bu]
+The mapped project IDs must in turn have a mapping
+in the parent user namespace.
+.P
+Violation of these rules causes
+.BR write (2)
+to fail with the error
+.BR EPERM .
+.\"
+.\" ============================================================
+.\"
+.SS Interaction with system calls that change process UIDs or GIDs
+In a user namespace where the
+.I uid_map
+file has not been written, the system calls that change user IDs will fail.
+Similarly, if the
+.I gid_map
+file has not been written, the system calls that change group IDs will fail.
+After the
+.I uid_map
+and
+.I gid_map
+files have been written, only the mapped values may be used in
+system calls that change user and group IDs.
+.P
+For user IDs, the relevant system calls include
+.BR setuid (2),
+.BR setfsuid (2),
+.BR setreuid (2),
+and
+.BR setresuid (2).
+For group IDs, the relevant system calls include
+.BR setgid (2),
+.BR setfsgid (2),
+.BR setregid (2),
+.BR setresgid (2),
+and
+.BR setgroups (2).
+.P
+Writing
+.RI \[dq] deny \[dq]
+to the
+.IR /proc/ pid /setgroups
+file before writing to
+.IR /proc/ pid /gid_map
+.\" Things changed in Linux 3.19
+.\" commit 9cc46516ddf497ea16e8d7cb986ae03a0f6b92f8
+.\" commit 66d2f338ee4c449396b6f99f5e75cd18eb6df272
+.\" http://lwn.net/Articles/626665/
+will permanently disable
+.BR setgroups (2)
+in a user namespace and allow writing to
+.IR /proc/ pid /gid_map
+without having the
+.B CAP_SETGID
+capability in the parent user namespace.
+.\"
+.\" ============================================================
+.\"
+.SS The \fI/proc/\fPpid\fI/setgroups\fP file
+.\"
+.\" commit 9cc46516ddf497ea16e8d7cb986ae03a0f6b92f8
+.\" commit 66d2f338ee4c449396b6f99f5e75cd18eb6df272
+.\" http://lwn.net/Articles/626665/
+.\" http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8989
+.\"
+The
+.IR /proc/ pid /setgroups
+file displays the string
+.RI \[dq] allow \[dq]
+if processes in the user namespace that contains the process
+.I pid
+are permitted to employ the
+.BR setgroups (2)
+system call; it displays
+.RI \[dq] deny \[dq]
+if
+.BR setgroups (2)
+is not permitted in that user namespace.
+Note that regardless of the value in the
+.IR /proc/ pid /setgroups
+file (and regardless of the process's capabilities), calls to
+.BR setgroups (2)
+are also not permitted if
+.IR /proc/ pid /gid_map
+has not yet been set.
+.P
+A privileged process (one with the
+.B CAP_SYS_ADMIN
+capability in the namespace) may write either of the strings
+.RI \[dq] allow \[dq]
+or
+.RI \[dq] deny \[dq]
+to this file
+.I before
+writing a group ID mapping
+for this user namespace to the file
+.IR /proc/ pid /gid_map .
+Writing the string
+.RI \[dq] deny \[dq]
+prevents any process in the user namespace from employing
+.BR setgroups (2).
+.P
+The essence of the restrictions described in the preceding
+paragraph is that it is permitted to write to
+.IR /proc/ pid /setgroups
+only so long as calling
+.BR setgroups (2)
+is disallowed because
+.IR /proc/ pid /gid_map
+has not been set.
+This ensures that a process cannot transition from a state where
+.BR setgroups (2)
+is allowed to a state where
+.BR setgroups (2)
+is denied;
+a process can transition only from
+.BR setgroups (2)
+being disallowed to
+.BR setgroups (2)
+being allowed.
+.P
+The default value of this file in the initial user namespace is
+.RI \[dq] allow \[dq].
+.P
+Once
+.IR /proc/ pid /gid_map
+has been written to
+(which has the effect of enabling
+.BR setgroups (2)
+in the user namespace),
+it is no longer possible to disallow
+.BR setgroups (2)
+by writing
+.RI \[dq] deny \[dq]
+to
+.IR /proc/ pid /setgroups
+(the write fails with the error
+.BR EPERM ).
+.P
+A child user namespace inherits the
+.IR /proc/ pid /setgroups
+setting from its parent.
+.P
+If the
+.I setgroups
+file has the value
+.RI \[dq] deny \[dq],
+then the
+.BR setgroups (2)
+system call can't subsequently be reenabled (by writing
+.RI \[dq] allow \[dq]
+to the file) in this user namespace.
+(Attempts to do so fail with the error
+.BR EPERM .)
+This restriction also propagates down to all child user namespaces of
+this user namespace.
+.P
+The
+.IR /proc/ pid /setgroups
+file was added in Linux 3.19,
+but was backported to many earlier stable kernel series,
+because it addresses a security issue.
+The issue concerned files with permissions such as "rwx\-\-\-rwx".
+Such files give fewer permissions to "group" than they do to "other".
+This means that dropping groups using
+.BR setgroups (2)
+might allow a process file access that it did not formerly have.
+Before the existence of user namespaces this was not a concern,
+since only a privileged process (one with the
+.B CAP_SETGID
+capability) could call
+.BR setgroups (2).
+However, with the introduction of user namespaces,
+it became possible for an unprivileged process to create
+a new namespace in which the user had all privileges.
+This then allowed formerly unprivileged
+users to drop groups and thus gain file access
+that they did not previously have.
+The
+.IR /proc/ pid /setgroups
+file was added to address this security issue,
+by denying any pathway for an unprivileged process to drop groups with
+.BR setgroups (2).
+.\"
+.\" /proc/PID/setgroups
+.\"	[allow == setgroups() is allowed, "deny" == setgroups() is disallowed]
+.\"	* Can write if have CAP_SYS_ADMIN in NS
+.\"	* Must write BEFORE writing to /proc/PID/gid_map
+.\"
+.\" setgroups()
+.\"	* Must already have written to gid_map
+.\"	* /proc/PID/setgroups must be "allow"
+.\"
+.\" /proc/PID/gid_map -- writing
+.\"	* Must already have written "deny" to /proc/PID/setgroups
+.\"
+.\" ============================================================
+.\"
+.SS Unmapped user and group IDs
+There are various places where an unmapped user ID (group ID)
+may be exposed to user space.
+For example, the first process in a new user namespace may call
+.BR getuid (2)
+before a user ID mapping has been defined for the namespace.
+In most such cases, an unmapped user ID is converted
+.\" from_kuid_munged(), from_kgid_munged()
+to the overflow user ID (group ID);
+the default value for the overflow user ID (group ID) is 65534.
+See the descriptions of
+.I /proc/sys/kernel/overflowuid
+and
+.I /proc/sys/kernel/overflowgid
+in
+.BR proc (5).
+.P
+The cases where unmapped IDs are mapped in this fashion include
+system calls that return user IDs
+.RB ( getuid (2),
+.BR getgid (2),
+and similar),
+credentials passed over a UNIX domain socket,
+.\" also SO_PEERCRED
+credentials returned by
+.BR stat (2),
+.BR waitid (2),
+and the System V IPC "ctl"
+.B IPC_STAT
+operations,
+credentials exposed by
+.IR /proc/ pid /status
+and the files in
+.IR /proc/sysvipc/* ,
+credentials returned via the
+.I si_uid
+field in the
+.I siginfo_t
+received with a signal (see
+.BR sigaction (2)),
+credentials written to the process accounting file (see
+.BR acct (5)),
+and credentials returned with POSIX message queue notifications (see
+.BR mq_notify (3)).
+.P
+There is one notable case where unmapped user and group IDs are
+.I not
+.\" from_kuid(), from_kgid()
+.\" Also F_GETOWNER_UIDS is an exception
+converted to the corresponding overflow ID value.
+When viewing a
+.I uid_map
+or
+.I gid_map
+file in which there is no mapping for the second field,
+that field is displayed as 4294967295 (\-1 as an unsigned integer).
+.\"
+.\" ============================================================
+.\"
+.SS Accessing files
+In order to determine permissions when an unprivileged process accesses a file,
+the process credentials (UID, GID) and the file credentials
+are in effect mapped back to what they would be in
+the initial user namespace and then compared to determine
+the permissions that the process has on the file.
+The same is also true of other objects that employ the credentials plus
+permissions mask accessibility model, such as System V IPC objects.
+.\"
+.\" ============================================================
+.\"
+.SS Operation of file-related capabilities
+Certain capabilities allow a process to bypass various
+kernel-enforced restrictions when performing operations on
+files owned by other users or groups.
+These capabilities are:
+.BR CAP_CHOWN ,
+.BR CAP_DAC_OVERRIDE ,
+.BR CAP_DAC_READ_SEARCH ,
+.BR CAP_FOWNER ,
+and
+.BR CAP_FSETID .
+.P
+Within a user namespace,
+these capabilities allow a process to bypass the rules
+if the process has the relevant capability over the file,
+meaning that:
+.IP \[bu] 3
+the process has the relevant effective capability in its user namespace; and
+.IP \[bu]
+the file's user ID and group ID both have valid mappings
+in the user namespace.
+.P
+The
+.B CAP_FOWNER
+capability is treated somewhat exceptionally:
+.\" These are the checks performed by the kernel function
+.\" inode_owner_or_capable(). There is one exception to the exception:
+.\" overriding the directory sticky permission bit requires that
+.\" the file has a valid mapping for both its UID and GID.
+it allows a process to bypass the corresponding rules so long as
+at least the file's user ID has a mapping in the user namespace
+(i.e., the file's group ID does not need to have a valid mapping).
+.\"
+.\" ============================================================
+.\"
+.SS Set-user-ID and set-group-ID programs
+When a process inside a user namespace executes
+a set-user-ID (set-group-ID) program,
+the process's effective user (group) ID inside the namespace is changed
+to whatever value is mapped for the user (group) ID of the file.
+However, if either the user
+.I or
+the group ID of the file has no mapping inside the namespace,
+the set-user-ID (set-group-ID) bit is silently ignored:
+the new program is executed,
+but the process's effective user (group) ID is left unchanged.
+(This mirrors the semantics of executing a set-user-ID or set-group-ID
+program that resides on a filesystem that was mounted with the
+.B MS_NOSUID
+flag, as described in
+.BR mount (2).)
+.\"
+.\" ============================================================
+.\"
+.SS Miscellaneous
+When a process's user and group IDs are passed over a UNIX domain socket
+to a process in a different user namespace (see the description of
+.B SCM_CREDENTIALS
+in
+.BR unix (7)),
+they are translated into the corresponding values as per the
+receiving process's user and group ID mappings.
+.\"
+.SH STANDARDS
+Linux.
+.\"
+.SH NOTES
+Over the years, there have been a lot of features that have been added
+to the Linux kernel that have been made available only to privileged users
+because of their potential to confuse set-user-ID-root applications.
+In general, it becomes safe to allow the root user in a user namespace to
+use those features because it is impossible, while in a user namespace,
+to gain more privilege than the root user of a user namespace has.
+.\"
+.\" ============================================================
+.\"
+.SS Global root
+The term "global root" is sometimes used as a shorthand for
+user ID 0 in the initial user namespace.
+.\"
+.\" ============================================================
+.\"
+.SS Availability
+Use of user namespaces requires a kernel that is configured with the
+.B CONFIG_USER_NS
+option.
+User namespaces require support in a range of subsystems across
+the kernel.
+When an unsupported subsystem is configured into the kernel,
+it is not possible to configure user namespaces support.
+.P
+As at Linux 3.8, most relevant subsystems supported user namespaces,
+but a number of filesystems did not have the infrastructure needed
+to map user and group IDs between user namespaces.
+Linux 3.9 added the required infrastructure support for many of
+the remaining unsupported filesystems
+(Plan 9 (9P), Andrew File System (AFS), Ceph, CIFS, CODA, NFS, and OCFS2).
+Linux 3.12 added support for the last of the unsupported major filesystems,
+.\" commit d6970d4b726cea6d7a9bc4120814f95c09571fc3
+XFS.
+.\"
+.SH EXAMPLES
+The program below is designed to allow experimenting with
+user namespaces, as well as other types of namespaces.
+It creates namespaces as specified by command-line options and then executes
+a command inside those namespaces.
+The comments and
+.IR usage ()
+function inside the program provide a full explanation of the program.
+The following shell session demonstrates its use.
+.P
+First, we look at the run-time environment:
+.P
+.in +4n
+.EX
+$ \fBuname \-rs\fP     # Need Linux 3.8 or later
+Linux 3.8.0
+$ \fBid \-u\fP         # Running as unprivileged user
+1000
+$ \fBid \-g\fP
+1000
+.EE
+.in
+.P
+Now start a new shell in new user
+.RI ( \-U ),
+mount
+.RI ( \-m ),
+and PID
+.RI ( \-p )
+namespaces, with user ID
+.RI ( \-M )
+and group ID
+.RI ( \-G )
+1000 mapped to 0 inside the user namespace:
+.P
+.in +4n
+.EX
+$ \fB./userns_child_exec \-p \-m \-U \-M \[aq]0 1000 1\[aq] \-G \[aq]0 1000 1\[aq] bash\fP
+.EE
+.in
+.P
+The shell has PID 1, because it is the first process in the new
+PID namespace:
+.P
+.in +4n
+.EX
+bash$ \fBecho $$\fP
+1
+.EE
+.in
+.P
+Mounting a new
+.I /proc
+filesystem and listing all of the processes visible
+in the new PID namespace shows that the shell can't see
+any processes outside the PID namespace:
+.P
+.in +4n
+.EX
+bash$ \fBmount \-t proc proc /proc\fP
+bash$ \fBps ax\fP
+  PID TTY      STAT   TIME COMMAND
+    1 pts/3    S      0:00 bash
+   22 pts/3    R+     0:00 ps ax
+.EE
+.in
+.P
+Inside the user namespace, the shell has user and group ID 0,
+and a full set of permitted and effective capabilities:
+.P
+.in +4n
+.EX
+bash$ \fBcat /proc/$$/status | egrep \[aq]\[ha][UG]id\[aq]\fP
+Uid:	0	0	0	0
+Gid:	0	0	0	0
+bash$ \fBcat /proc/$$/status | egrep \[aq]\[ha]Cap(Prm|Inh|Eff)\[aq]\fP
+CapInh:	0000000000000000
+CapPrm:	0000001fffffffff
+CapEff:	0000001fffffffff
+.EE
+.in
+.SS Program source
+\&
+.EX
+/* userns_child_exec.c
+\&
+   Licensed under GNU General Public License v2 or later
+\&
+   Create a child process that executes a shell command in new
+   namespace(s); allow UID and GID mappings to be specified when
+   creating a user namespace.
+*/
+#define _GNU_SOURCE
+#include <err.h>
+#include <sched.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>
+#include <errno.h>
+\&
+struct child_args {
+    char **argv;        /* Command to be executed by child, with args */
+    int    pipe_fd[2];  /* Pipe used to synchronize parent and child */
+};
+\&
+static int verbose;
+\&
+static void
+usage(char *pname)
+{
+    fprintf(stderr, "Usage: %s [options] cmd [arg...]\en\en", pname);
+    fprintf(stderr, "Create a child process that executes a shell "
+            "command in a new user namespace,\en"
+            "and possibly also other new namespace(s).\en\en");
+    fprintf(stderr, "Options can be:\en\en");
+#define fpe(str) fprintf(stderr, "    %s", str);
+    fpe("\-i          New IPC namespace\en");
+    fpe("\-m          New mount namespace\en");
+    fpe("\-n          New network namespace\en");
+    fpe("\-p          New PID namespace\en");
+    fpe("\-u          New UTS namespace\en");
+    fpe("\-U          New user namespace\en");
+    fpe("\-M uid_map  Specify UID map for user namespace\en");
+    fpe("\-G gid_map  Specify GID map for user namespace\en");
+    fpe("\-z          Map user\[aq]s UID and GID to 0 in user namespace\en");
+    fpe("            (equivalent to: \-M \[aq]0 <uid> 1\[aq] \-G \[aq]0 <gid> 1\[aq])\en");
+    fpe("\-v          Display verbose messages\en");
+    fpe("\en");
+    fpe("If \-z, \-M, or \-G is specified, \-U is required.\en");
+    fpe("It is not permitted to specify both \-z and either \-M or \-G.\en");
+    fpe("\en");
+    fpe("Map strings for \-M and \-G consist of records of the form:\en");
+    fpe("\en");
+    fpe("    ID\-inside\-ns   ID\-outside\-ns   len\en");
+    fpe("\en");
+    fpe("A map string can contain multiple records, separated"
+        " by commas;\en");
+    fpe("the commas are replaced by newlines before writing"
+        " to map files.\en");
+\&
+    exit(EXIT_FAILURE);
+}
+\&
+/* Update the mapping file \[aq]map_file\[aq], with the value provided in
+   \[aq]mapping\[aq], a string that defines a UID or GID mapping. A UID or
+   GID mapping consists of one or more newline\-delimited records
+   of the form:
+\&
+       ID_inside\-ns    ID\-outside\-ns   length
+\&
+   Requiring the user to supply a string that contains newlines is
+   of course inconvenient for command\-line use. Thus, we permit the
+   use of commas to delimit records in this string, and replace them
+   with newlines before writing the string to the file. */
+\&
+static void
+update_map(char *mapping, char *map_file)
+{
+    int fd;
+    size_t map_len;     /* Length of \[aq]mapping\[aq] */
+\&
+    /* Replace commas in mapping string with newlines. */
+\&
+    map_len = strlen(mapping);
+    for (size_t j = 0; j < map_len; j++)
+        if (mapping[j] == \[aq],\[aq])
+            mapping[j] = \[aq]\en\[aq];
+\&
+    fd = open(map_file, O_RDWR);
+    if (fd == \-1) {
+        fprintf(stderr, "ERROR: open %s: %s\en", map_file,
+                strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    if (write(fd, mapping, map_len) != map_len) {
+        fprintf(stderr, "ERROR: write %s: %s\en", map_file,
+                strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+\&
+    close(fd);
+}
+\&
+/* Linux 3.19 made a change in the handling of setgroups(2) and
+   the \[aq]gid_map\[aq] file to address a security issue.  The issue
+   allowed *unprivileged* users to employ user namespaces in
+   order to drop groups.  The upshot of the 3.19 changes is that
+   in order to update the \[aq]gid_maps\[aq] file, use of the setgroups()
+   system call in this user namespace must first be disabled by
+   writing "deny" to one of the /proc/PID/setgroups files for
+   this namespace.  That is the purpose of the following function.  */
+\&
+static void
+proc_setgroups_write(pid_t child_pid, char *str)
+{
+    char setgroups_path[PATH_MAX];
+    int fd;
+\&
+    snprintf(setgroups_path, PATH_MAX, "/proc/%jd/setgroups",
+            (intmax_t) child_pid);
+\&
+    fd = open(setgroups_path, O_RDWR);
+    if (fd == \-1) {
+\&
+        /* We may be on a system that doesn\[aq]t support
+           /proc/PID/setgroups. In that case, the file won\[aq]t exist,
+           and the system won\[aq]t impose the restrictions that Linux 3.19
+           added. That\[aq]s fine: we don\[aq]t need to do anything in order
+           to permit \[aq]gid_map\[aq] to be updated.
+\&
+           However, if the error from open() was something other than
+           the ENOENT error that is expected for that case,  let the
+           user know. */
+\&
+        if (errno != ENOENT)
+            fprintf(stderr, "ERROR: open %s: %s\en", setgroups_path,
+                strerror(errno));
+        return;
+    }
+\&
+    if (write(fd, str, strlen(str)) == \-1)
+        fprintf(stderr, "ERROR: write %s: %s\en", setgroups_path,
+            strerror(errno));
+\&
+    close(fd);
+}
+\&
+static int              /* Start function for cloned child */
+childFunc(void *arg)
+{
+    struct child_args *args = arg;
+    char ch;
+\&
+    /* Wait until the parent has updated the UID and GID mappings.
+       See the comment in main(). We wait for end of file on a
+       pipe that will be closed by the parent process once it has
+       updated the mappings. */
+\&
+    close(args\->pipe_fd[1]);    /* Close our descriptor for the write
+                                   end of the pipe so that we see EOF
+                                   when parent closes its descriptor. */
+    if (read(args\->pipe_fd[0], &ch, 1) != 0) {
+        fprintf(stderr,
+                "Failure in child: read from pipe returned != 0\en");
+        exit(EXIT_FAILURE);
+    }
+\&
+    close(args\->pipe_fd[0]);
+\&
+    /* Execute a shell command. */
+\&
+    printf("About to exec %s\en", args\->argv[0]);
+    execvp(args\->argv[0], args\->argv);
+    err(EXIT_FAILURE, "execvp");
+}
+\&
+#define STACK_SIZE (1024 * 1024)
+\&
+static char child_stack[STACK_SIZE];    /* Space for child\[aq]s stack */
+\&
+int
+main(int argc, char *argv[])
+{
+    int flags, opt, map_zero;
+    pid_t child_pid;
+    struct child_args args;
+    char *uid_map, *gid_map;
+    const int MAP_BUF_SIZE = 100;
+    char map_buf[MAP_BUF_SIZE];
+    char map_path[PATH_MAX];
+\&
+    /* Parse command\-line options. The initial \[aq]+\[aq] character in
+       the final getopt() argument prevents GNU\-style permutation
+       of command\-line options. That\[aq]s useful, since sometimes
+       the \[aq]command\[aq] to be executed by this program itself
+       has command\-line options. We don\[aq]t want getopt() to treat
+       those as options to this program. */
+\&
+    flags = 0;
+    verbose = 0;
+    gid_map = NULL;
+    uid_map = NULL;
+    map_zero = 0;
+    while ((opt = getopt(argc, argv, "+imnpuUM:G:zv")) != \-1) {
+        switch (opt) {
+        case \[aq]i\[aq]: flags |= CLONE_NEWIPC;        break;
+        case \[aq]m\[aq]: flags |= CLONE_NEWNS;         break;
+        case \[aq]n\[aq]: flags |= CLONE_NEWNET;        break;
+        case \[aq]p\[aq]: flags |= CLONE_NEWPID;        break;
+        case \[aq]u\[aq]: flags |= CLONE_NEWUTS;        break;
+        case \[aq]v\[aq]: verbose = 1;                  break;
+        case \[aq]z\[aq]: map_zero = 1;                 break;
+        case \[aq]M\[aq]: uid_map = optarg;             break;
+        case \[aq]G\[aq]: gid_map = optarg;             break;
+        case \[aq]U\[aq]: flags |= CLONE_NEWUSER;       break;
+        default:  usage(argv[0]);
+        }
+    }
+\&
+    /* \-M or \-G without \-U is nonsensical */
+\&
+    if (((uid_map != NULL || gid_map != NULL || map_zero) &&
+                !(flags & CLONE_NEWUSER)) ||
+            (map_zero && (uid_map != NULL || gid_map != NULL)))
+        usage(argv[0]);
+\&
+    args.argv = &argv[optind];
+\&
+    /* We use a pipe to synchronize the parent and child, in order to
+       ensure that the parent sets the UID and GID maps before the child
+       calls execve(). This ensures that the child maintains its
+       capabilities during the execve() in the common case where we
+       want to map the child\[aq]s effective user ID to 0 in the new user
+       namespace. Without this synchronization, the child would lose
+       its capabilities if it performed an execve() with nonzero
+       user IDs (see the capabilities(7) man page for details of the
+       transformation of a process\[aq]s capabilities during execve()). */
+\&
+    if (pipe(args.pipe_fd) == \-1)
+        err(EXIT_FAILURE, "pipe");
+\&
+    /* Create the child in new namespace(s). */
+\&
+    child_pid = clone(childFunc, child_stack + STACK_SIZE,
+                      flags | SIGCHLD, &args);
+    if (child_pid == \-1)
+        err(EXIT_FAILURE, "clone");
+\&
+    /* Parent falls through to here. */
+\&
+    if (verbose)
+        printf("%s: PID of child created by clone() is %jd\en",
+                argv[0], (intmax_t) child_pid);
+\&
+    /* Update the UID and GID maps in the child. */
+\&
+    if (uid_map != NULL || map_zero) {
+        snprintf(map_path, PATH_MAX, "/proc/%jd/uid_map",
+                (intmax_t) child_pid);
+        if (map_zero) {
+            snprintf(map_buf, MAP_BUF_SIZE, "0 %jd 1",
+                    (intmax_t) getuid());
+            uid_map = map_buf;
+        }
+        update_map(uid_map, map_path);
+    }
+\&
+    if (gid_map != NULL || map_zero) {
+        proc_setgroups_write(child_pid, "deny");
+\&
+        snprintf(map_path, PATH_MAX, "/proc/%jd/gid_map",
+                (intmax_t) child_pid);
+        if (map_zero) {
+            snprintf(map_buf, MAP_BUF_SIZE, "0 %ld 1",
+                    (intmax_t) getgid());
+            gid_map = map_buf;
+        }
+        update_map(gid_map, map_path);
+    }
+\&
+    /* Close the write end of the pipe, to signal to the child that we
+       have updated the UID and GID maps. */
+\&
+    close(args.pipe_fd[1]);
+\&
+    if (waitpid(child_pid, NULL, 0) == \-1)      /* Wait for child */
+        err(EXIT_FAILURE, "waitpid");
+\&
+    if (verbose)
+        printf("%s: terminating\en", argv[0]);
+\&
+    exit(EXIT_SUCCESS);
+}
+.EE
+.SH SEE ALSO
+.BR newgidmap (1),      \" From the shadow package
+.BR newuidmap (1),      \" From the shadow package
+.BR clone (2),
+.BR ptrace (2),
+.BR setns (2),
+.BR unshare (2),
+.BR proc (5),
+.BR subgid (5),         \" From the shadow package
+.BR subuid (5),         \" From the shadow package
+.BR capabilities (7),
+.BR cgroup_namespaces (7),
+.BR credentials (7),
+.BR namespaces (7),
+.BR pid_namespaces (7)
+.P
+The kernel source file
+.IR Documentation/admin\-guide/namespaces/resource\-control.rst .
diff --git a/man/man7/utf-8.7 b/man/man7/utf-8.7
new file mode 100644
index 000000000..d6f539ab2
--- /dev/null
+++ b/man/man7/utf-8.7
@@ -0,0 +1,205 @@
+.\" Copyright (C) Markus Kuhn, 1996, 2001
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 1995-11-26  Markus Kuhn <mskuhn@cip.informatik.uni-erlangen.de>
+.\"      First version written
+.\" 2001-05-11  Markus Kuhn <mgk25@cl.cam.ac.uk>
+.\"      Update
+.\"
+.TH UTF-8 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+UTF-8 \- an ASCII compatible multibyte Unicode encoding
+.SH DESCRIPTION
+The Unicode 3.0 character set occupies a 16-bit code space.
+The most obvious
+Unicode encoding (known as UCS-2)
+consists of a sequence of 16-bit words.
+Such strings can contain\[em]as part of many 16-bit characters\[em]bytes
+such as \[aq]\e0\[aq] or \[aq]/\[aq], which have a
+special meaning in filenames and other C library function arguments.
+In addition, the majority of UNIX tools expect ASCII files and can't
+read 16-bit words as characters without major modifications.
+For these reasons,
+UCS-2 is not a suitable external encoding of Unicode
+in filenames, text files, environment variables, and so on.
+The ISO/IEC 10646 Universal Character Set (UCS),
+a superset of Unicode, occupies an even larger code
+space\[em]31\ bits\[em]and the obvious
+UCS-4 encoding for it (a sequence of 32-bit words) has the same problems.
+.P
+The UTF-8 encoding of Unicode and UCS
+does not have these problems and is the common way in which
+Unicode is used on UNIX-style operating systems.
+.SS Properties
+The UTF-8 encoding has the following nice properties:
+.IP \[bu] 3
+UCS
+characters 0x00000000 to 0x0000007f (the classic US-ASCII
+characters) are encoded simply as bytes 0x00 to 0x7f (ASCII
+compatibility).
+This means that files and strings which contain only
+7-bit ASCII characters have the same encoding under both
+ASCII
+and
+UTF-8.
+.IP \[bu]
+All UCS characters greater than 0x7f are encoded as a multibyte sequence
+consisting only of bytes in the range 0x80 to 0xfd, so no ASCII
+byte can appear as part of another character and there are no
+problems with, for example,  \[aq]\e0\[aq] or \[aq]/\[aq].
+.IP \[bu]
+The lexicographic sorting order of UCS-4 strings is preserved.
+.IP \[bu]
+All possible 2\[ha]31 UCS codes can be encoded using UTF-8.
+.IP \[bu]
+The bytes 0xc0, 0xc1, 0xfe, and 0xff are never used in the UTF-8 encoding.
+.IP \[bu]
+The first byte of a multibyte sequence which represents a single non-ASCII
+UCS character is always in the range 0xc2 to 0xfd and indicates how long
+this multibyte sequence is.
+All further bytes in a multibyte sequence
+are in the range 0x80 to 0xbf.
+This allows easy resynchronization and
+makes the encoding stateless and robust against missing bytes.
+.IP \[bu]
+UTF-8 encoded UCS characters may be up to six bytes long, however the
+Unicode standard specifies no characters above 0x10ffff, so Unicode characters
+can be only up to four bytes long in
+UTF-8.
+.SS Encoding
+The following byte sequences are used to represent a character.
+The sequence to be used depends on the UCS code number of the character:
+.TP
+0x00000000 \- 0x0000007F:
+.RI 0 xxxxxxx
+.TP
+0x00000080 \- 0x000007FF:
+.RI 110 xxxxx
+.RI 10 xxxxxx
+.TP
+0x00000800 \- 0x0000FFFF:
+.RI 1110 xxxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.TP
+0x00010000 \- 0x001FFFFF:
+.RI 11110 xxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.TP
+0x00200000 \- 0x03FFFFFF:
+.RI 111110 xx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.TP
+0x04000000 \- 0x7FFFFFFF:
+.RI 1111110 x
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.RI 10 xxxxxx
+.P
+The
+.I xxx
+bit positions are filled with the bits of the character code number in
+binary representation, most significant bit first (big-endian).
+Only the shortest possible multibyte sequence
+which can represent the code number of the character can be used.
+.P
+The UCS code values 0xd800\[en]0xdfff (UTF-16 surrogates) as well as 0xfffe and
+0xffff (UCS noncharacters) should not appear in conforming UTF-8 streams.
+According to RFC 3629 no point above U+10FFFF should be used,
+which limits characters to four bytes.
+.SS Example
+The Unicode character 0xa9 = 1010 1001 (the copyright sign) is encoded
+in UTF-8 as
+.P
+.RS
+11000010 10101001 = 0xc2 0xa9
+.RE
+.P
+and character 0x2260 = 0010 0010 0110 0000 (the "not equal" symbol) is
+encoded as:
+.P
+.RS
+11100010 10001001 10100000 = 0xe2 0x89 0xa0
+.RE
+.SS Application notes
+Users have to select a UTF-8 locale, for example with
+.P
+.RS
+export LANG=en_GB.UTF-8
+.RE
+.P
+in order to activate the UTF-8 support in applications.
+.P
+Application software that has to be aware of the used character
+encoding should always set the locale with for example
+.P
+.RS
+setlocale(LC_CTYPE, "")
+.RE
+.P
+and programmers can then test the expression
+.P
+.RS
+strcmp(nl_langinfo(CODESET), "UTF-8") == 0
+.RE
+.P
+to determine whether a UTF-8 locale has been selected and whether
+therefore all plaintext standard input and output, terminal
+communication, plaintext file content, filenames, and environment
+variables are encoded in UTF-8.
+.P
+Programmers accustomed to single-byte encodings
+such as US-ASCII or ISO/IEC\~8859
+have to be aware that two assumptions made so far are no longer valid
+in UTF-8 locales.
+Firstly, a single byte does not necessarily correspond any
+more to a single character.
+Secondly, since modern terminal emulators in UTF-8
+mode also support Chinese, Japanese, and Korean
+double-width characters as well as nonspacing combining characters,
+outputting a single character does not necessarily advance the cursor
+by one position as it did in ASCII.
+Library functions such as
+.BR mbsrtowcs (3)
+and
+.BR wcswidth (3)
+should be used today to count characters and cursor positions.
+.P
+The official ESC sequence to switch from an ISO/IEC\~2022
+encoding scheme (as used for instance by VT100 terminals) to
+UTF-8 is ESC % G
+("\ex1b%G").
+The corresponding return sequence from
+UTF-8 to ISO/IEC\~2022 is ESC % @ ("\ex1b%@").
+Other ISO/IEC\~2022 sequences (such as
+for switching the G0 and G1 sets) are not applicable in UTF-8 mode.
+.SS Security
+The Unicode and UCS standards require that producers of UTF-8
+shall use the shortest form possible, for example, producing a two-byte
+sequence with first byte 0xc0 is nonconforming.
+Unicode 3.1 has added the requirement that conforming programs must not accept
+non-shortest forms in their input.
+This is for security reasons: if
+user input is checked for possible security violations, a program
+might check only for the ASCII
+version of "/../" or ";" or NUL and overlook that there are many
+non-ASCII ways to represent these things in a non-shortest UTF-8
+encoding.
+.SS Standards
+ISO/IEC 10646-1:2000, Unicode 3.1, RFC\ 3629, Plan 9.
+.\" .SH AUTHOR
+.\" Markus Kuhn <mgk25@cl.cam.ac.uk>
+.SH SEE ALSO
+.BR locale (1),
+.BR nl_langinfo (3),
+.BR setlocale (3),
+.BR charsets (7),
+.BR unicode (7)
diff --git a/man/man7/utf8.7 b/man/man7/utf8.7
new file mode 100644
index 000000000..52a90084f
--- /dev/null
+++ b/man/man7/utf8.7
@@ -0,0 +1 @@
+.so man7/utf-8.7
diff --git a/man/man7/uts_namespaces.7 b/man/man7/uts_namespaces.7
new file mode 100644
index 000000000..df4bdba3f
--- /dev/null
+++ b/man/man7/uts_namespaces.7
@@ -0,0 +1,46 @@
+.\" Copyright (c) 2019 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\"
+.TH uts_namespaces 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+uts_namespaces \- overview of Linux UTS namespaces
+.SH DESCRIPTION
+UTS namespaces provide isolation of two system identifiers:
+the hostname and the NIS domain name.
+These identifiers are set using
+.BR sethostname (2)
+and
+.BR setdomainname (2),
+and can be retrieved using
+.BR uname (2),
+.BR gethostname (2),
+and
+.BR getdomainname (2).
+Changes made to these identifiers are visible to all other
+processes in the same UTS namespace,
+but are not visible to processes in other UTS namespaces.
+.P
+When a process creates a new UTS namespace using
+.BR clone (2)
+or
+.BR unshare (2)
+with the
+.B CLONE_NEWUTS
+flag, the hostname and domain name of the new UTS namespace are copied
+from the corresponding values in the caller's UTS namespace.
+.P
+Use of UTS namespaces requires a kernel that is configured with the
+.B CONFIG_UTS_NS
+option.
+.SH SEE ALSO
+.BR nsenter (1),
+.BR unshare (1),
+.BR clone (2),
+.BR getdomainname (2),
+.BR gethostname (2),
+.BR setns (2),
+.BR uname (2),
+.BR unshare (2),
+.BR namespaces (7)
diff --git a/man/man7/vdso.7 b/man/man7/vdso.7
new file mode 100644
index 000000000..de5f300cd
--- /dev/null
+++ b/man/man7/vdso.7
@@ -0,0 +1,612 @@
+'\" t
+.\" Written by Mike Frysinger <vapier@gentoo.org>
+.\"
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This page is in the public domain.
+.\" %%%LICENSE_END
+.\"
+.\" Useful background:
+.\"   http://articles.manugarg.com/systemcallinlinux2_6.html
+.\"   https://lwn.net/Articles/446528/
+.\"   http://www.linuxjournal.com/content/creating-vdso-colonels-other-chicken
+.\"   http://www.trilithium.com/johan/2005/08/linux-gate/
+.\"
+.TH vDSO 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+vdso \- overview of the virtual ELF dynamic shared object
+.SH SYNOPSIS
+.nf
+.B #include <sys/auxv.h>
+.P
+.B void *vdso = (uintptr_t) getauxval(AT_SYSINFO_EHDR);
+.fi
+.SH DESCRIPTION
+The "vDSO" (virtual dynamic shared object) is a small shared library that
+the kernel automatically maps into the
+address space of all user-space applications.
+Applications usually do not need to concern themselves with these details
+as the vDSO is most commonly called by the C library.
+This way you can code in the normal way using standard functions
+and the C library will take care
+of using any functionality that is available via the vDSO.
+.P
+Why does the vDSO exist at all?
+There are some system calls the kernel provides that
+user-space code ends up using frequently,
+to the point that such calls can dominate overall performance.
+This is due both to the frequency of the call as well as the
+context-switch overhead that results
+from exiting user space and entering the kernel.
+.P
+The rest of this documentation is geared toward the curious and/or
+C library writers rather than general developers.
+If you're trying to call the vDSO in your own application rather than using
+the C library, you're most likely doing it wrong.
+.SS Example background
+Making system calls can be slow.
+In x86 32-bit systems, you can trigger a software interrupt
+.RI ( "int $0x80" )
+to tell the kernel you wish to make a system call.
+However, this instruction is expensive: it goes through
+the full interrupt-handling paths
+in the processor's microcode as well as in the kernel.
+Newer processors have faster (but backward incompatible) instructions to
+initiate system calls.
+Rather than require the C library to figure out if this functionality is
+available at run time,
+the C library can use functions provided by the kernel in
+the vDSO.
+.P
+Note that the terminology can be confusing.
+On x86 systems, the vDSO function
+used to determine the preferred method of making a system call is
+named "__kernel_vsyscall", but on x86-64,
+the term "vsyscall" also refers to an obsolete way to ask the kernel
+what time it is or what CPU the caller is on.
+.P
+One frequently used system call is
+.BR gettimeofday (2).
+This system call is called both directly by user-space applications
+as well as indirectly by
+the C library.
+Think timestamps or timing loops or polling\[em]all of these
+frequently need to know what time it is right now.
+This information is also not secret\[em]any application in any
+privilege mode (root or any unprivileged user) will get the same answer.
+Thus the kernel arranges for the information required to answer
+this question to be placed in memory the process can access.
+Now a call to
+.BR gettimeofday (2)
+changes from a system call to a normal function
+call and a few memory accesses.
+.SS Finding the vDSO
+The base address of the vDSO (if one exists) is passed by the kernel to
+each program in the initial auxiliary vector (see
+.BR getauxval (3)),
+via the
+.B AT_SYSINFO_EHDR
+tag.
+.P
+You must not assume the vDSO is mapped at any particular location in the
+user's memory map.
+The base address will usually be randomized at run time every time a new
+process image is created (at
+.BR execve (2)
+time).
+This is done for security reasons,
+to prevent "return-to-libc" attacks.
+.P
+For some architectures, there is also an
+.B AT_SYSINFO
+tag.
+This is used only for locating the vsyscall entry point and is frequently
+omitted or set to 0 (meaning it's not available).
+This tag is a throwback to the initial vDSO work (see
+.I History
+below) and its use should be avoided.
+.SS File format
+Since the vDSO is a fully formed ELF image, you can do symbol lookups on it.
+This allows new symbols to be added with newer kernel releases,
+and allows the C library to detect available functionality at
+run time when running under different kernel versions.
+Oftentimes the C library will do detection with the first call and then
+cache the result for subsequent calls.
+.P
+All symbols are also versioned (using the GNU version format).
+This allows the kernel to update the function signature without breaking
+backward compatibility.
+This means changing the arguments that the function accepts as well as the
+return value.
+Thus, when looking up a symbol in the vDSO,
+you must always include the version
+to match the ABI you expect.
+.P
+Typically the vDSO follows the naming convention of prefixing
+all symbols with "__vdso_" or "__kernel_"
+so as to distinguish them from other standard symbols.
+For example, the "gettimeofday" function is named "__vdso_gettimeofday".
+.P
+You use the standard C calling conventions when calling
+any of these functions.
+No need to worry about weird register or stack behavior.
+.SH NOTES
+.SS Source
+When you compile the kernel,
+it will automatically compile and link the vDSO code for you.
+You will frequently find it under the architecture-specific directory:
+.P
+.in +4n
+.EX
+find arch/$ARCH/ \-name \[aq]*vdso*.so*\[aq] \-o \-name \[aq]*gate*.so*\[aq]
+.EE
+.in
+.\"
+.SS vDSO names
+The name of the vDSO varies across architectures.
+It will often show up in things like glibc's
+.BR ldd (1)
+output.
+The exact name should not matter to any code, so do not hardcode it.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+user ABI	vDSO name
+_
+aarch64	linux\-vdso.so.1
+arm	linux\-vdso.so.1
+ia64	linux\-gate.so.1
+mips	linux\-vdso.so.1
+ppc/32	linux\-vdso32.so.1
+ppc/64	linux\-vdso64.so.1
+riscv	linux\-vdso.so.1
+s390	linux\-vdso32.so.1
+s390x	linux\-vdso64.so.1
+sh	linux\-gate.so.1
+i386	linux\-gate.so.1
+x86-64	linux\-vdso.so.1
+x86/x32	linux\-vdso.so.1
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS strace(1), seccomp(2), and the vDSO
+When tracing system calls with
+.BR strace (1),
+symbols (system calls) that are exported by the vDSO will
+.I not
+appear in the trace output.
+Those system calls will likewise not be visible to
+.BR seccomp (2)
+filters.
+.SH ARCHITECTURE-SPECIFIC NOTES
+The subsections below provide architecture-specific notes
+on the vDSO.
+.P
+Note that the vDSO that is used is based on the ABI of your user-space code
+and not the ABI of the kernel.
+Thus, for example,
+when you run an i386 32-bit ELF binary,
+you'll get the same vDSO regardless of whether you run it under
+an i386 32-bit kernel or under an x86-64 64-bit kernel.
+Therefore, the name of the user-space ABI should be used to determine
+which of the sections below is relevant.
+.SS ARM functions
+.\" See linux/arch/arm/vdso/vdso.lds.S
+.\" Commit: 8512287a8165592466cb9cb347ba94892e9c56a5
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__vdso_gettimeofday	LINUX_2.6 (exported since Linux 4.1)
+__vdso_clock_gettime	LINUX_2.6 (exported since Linux 4.1)
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.P
+.\" See linux/arch/arm/kernel/entry-armv.S
+.\" See linux/Documentation/arm/kernel_user_helpers.rst
+Additionally, the ARM port has a code page full of utility functions.
+Since it's just a raw page of code, there is no ELF information for doing
+symbol lookups or versioning.
+It does provide support for different versions though.
+.P
+For information on this code page,
+it's best to refer to the kernel documentation
+as it's extremely detailed and covers everything you need to know:
+.IR Documentation/arm/kernel_user_helpers.rst .
+.SS aarch64 functions
+.\" See linux/arch/arm64/kernel/vdso/vdso.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_rt_sigreturn	LINUX_2.6.39
+__kernel_gettimeofday	LINUX_2.6.39
+__kernel_clock_gettime	LINUX_2.6.39
+__kernel_clock_getres	LINUX_2.6.39
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS bfin (Blackfin) functions (port removed in Linux 4.17)
+.\" See linux/arch/blackfin/kernel/fixed_code.S
+.\" See http://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:fixed-code
+As this CPU lacks a memory management unit (MMU),
+it doesn't set up a vDSO in the normal sense.
+Instead, it maps at boot time a few raw functions into
+a fixed location in memory.
+User-space applications then call directly into that region.
+There is no provision for backward compatibility
+beyond sniffing raw opcodes,
+but as this is an embedded CPU, it can get away with things\[em]some of the
+object formats it runs aren't even ELF based (they're bFLT/FLAT).
+.P
+For information on this code page,
+it's best to refer to the public documentation:
+.br
+http://docs.blackfin.uclinux.org/doku.php?id=linux\-kernel:fixed\-code
+.SS mips functions
+.\" See linux/arch/mips/vdso/vdso.ld.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_gettimeofday	LINUX_2.6 (exported since Linux 4.4)
+__kernel_clock_gettime	LINUX_2.6 (exported since Linux 4.4)
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS ia64 (Itanium) functions
+.\" See linux/arch/ia64/kernel/gate.lds.S
+.\" Also linux/arch/ia64/kernel/fsys.S and linux/Documentation/ia64/fsys.rst
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_sigtramp	LINUX_2.5
+__kernel_syscall_via_break	LINUX_2.5
+__kernel_syscall_via_epc	LINUX_2.5
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.P
+The Itanium port is somewhat tricky.
+In addition to the vDSO above, it also has "light-weight system calls"
+(also known as "fast syscalls" or "fsys").
+You can invoke these via the
+.I __kernel_syscall_via_epc
+vDSO helper.
+The system calls listed here have the same semantics as if you called them
+directly via
+.BR syscall (2),
+so refer to the relevant
+documentation for each.
+The table below lists the functions available via this mechanism.
+.if t \{\
+.ft CW
+\}
+.TS
+l.
+function
+_
+clock_gettime
+getcpu
+getpid
+getppid
+gettimeofday
+set_tid_address
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS parisc (hppa) functions
+.\" See linux/arch/parisc/kernel/syscall.S
+.\" See linux/Documentation/parisc/registers.rst
+The parisc port has a code page with utility functions
+called a gateway page.
+Rather than use the normal ELF auxiliary vector approach,
+it passes the address of
+the page to the process via the SR2 register.
+The permissions on the page are such that merely executing those addresses
+automatically executes with kernel privileges and not in user space.
+This is done to match the way HP-UX works.
+.P
+Since it's just a raw page of code, there is no ELF information for doing
+symbol lookups or versioning.
+Simply call into the appropriate offset via the branch instruction,
+for example:
+.P
+.in +4n
+.EX
+ble <offset>(%sr2, %r0)
+.EE
+.in
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+offset	function
+_
+00b0	lws_entry (CAS operations)
+00e0	set_thread_pointer (used by glibc)
+0100	linux_gateway_entry (syscall)
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS ppc/32 functions
+.\" See linux/arch/powerpc/kernel/vdso32/vdso32.lds.S
+The table below lists the symbols exported by the vDSO.
+The functions marked with a
+.I *
+are available only when the kernel is
+a PowerPC64 (64-bit) kernel.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_clock_getres	LINUX_2.6.15
+__kernel_clock_gettime	LINUX_2.6.15
+__kernel_clock_gettime64	LINUX_5.11
+__kernel_datapage_offset	LINUX_2.6.15
+__kernel_get_syscall_map	LINUX_2.6.15
+__kernel_get_tbfreq	LINUX_2.6.15
+__kernel_getcpu \fI*\fR	LINUX_2.6.15
+__kernel_gettimeofday	LINUX_2.6.15
+__kernel_sigtramp_rt32	LINUX_2.6.15
+__kernel_sigtramp32	LINUX_2.6.15
+__kernel_sync_dicache	LINUX_2.6.15
+__kernel_sync_dicache_p5	LINUX_2.6.15
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.P
+Before Linux 5.6,
+.\" commit 654abc69ef2e69712e6d4e8a6cb9292b97a4aa39
+the
+.B CLOCK_REALTIME_COARSE
+and
+.B CLOCK_MONOTONIC_COARSE
+clocks are
+.I not
+supported by the
+.I __kernel_clock_getres
+and
+.I __kernel_clock_gettime
+interfaces;
+the kernel falls back to the real system call.
+.SS ppc/64 functions
+.\" See linux/arch/powerpc/kernel/vdso64/vdso64.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_clock_getres	LINUX_2.6.15
+__kernel_clock_gettime	LINUX_2.6.15
+__kernel_datapage_offset	LINUX_2.6.15
+__kernel_get_syscall_map	LINUX_2.6.15
+__kernel_get_tbfreq	LINUX_2.6.15
+__kernel_getcpu	LINUX_2.6.15
+__kernel_gettimeofday	LINUX_2.6.15
+__kernel_sigtramp_rt64	LINUX_2.6.15
+__kernel_sync_dicache	LINUX_2.6.15
+__kernel_sync_dicache_p5	LINUX_2.6.15
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.P
+Before Linux 4.16,
+.\" commit 5c929885f1bb4b77f85b1769c49405a0e0f154a1
+the
+.B CLOCK_REALTIME_COARSE
+and
+.B CLOCK_MONOTONIC_COARSE
+clocks are
+.I not
+supported by the
+.I __kernel_clock_getres
+and
+.I __kernel_clock_gettime
+interfaces;
+the kernel falls back to the real system call.
+.SS riscv functions
+.\" See linux/arch/riscv/kernel/vdso/vdso.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__vdso_rt_sigreturn	LINUX_4.15
+__vdso_gettimeofday	LINUX_4.15
+__vdso_clock_gettime	LINUX_4.15
+__vdso_clock_getres	LINUX_4.15
+__vdso_getcpu	LINUX_4.15
+__vdso_flush_icache	LINUX_4.15
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS s390 functions
+.\" See linux/arch/s390/kernel/vdso32/vdso32.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_clock_getres	LINUX_2.6.29
+__kernel_clock_gettime	LINUX_2.6.29
+__kernel_gettimeofday	LINUX_2.6.29
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS s390x functions
+.\" See linux/arch/s390/kernel/vdso64/vdso64.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_clock_getres	LINUX_2.6.29
+__kernel_clock_gettime	LINUX_2.6.29
+__kernel_gettimeofday	LINUX_2.6.29
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS sh (SuperH) functions
+.\" See linux/arch/sh/kernel/vsyscall/vsyscall.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_rt_sigreturn	LINUX_2.6
+__kernel_sigreturn	LINUX_2.6
+__kernel_vsyscall	LINUX_2.6
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS i386 functions
+.\" See linux/arch/x86/vdso/vdso32/vdso32.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__kernel_sigreturn	LINUX_2.5
+__kernel_rt_sigreturn	LINUX_2.5
+__kernel_vsyscall	LINUX_2.5
+.\" Added in 7a59ed415f5b57469e22e41fc4188d5399e0b194 and updated
+.\" in 37c975545ec63320789962bf307f000f08fabd48.
+__vdso_clock_gettime	LINUX_2.6 (exported since Linux 3.15)
+__vdso_gettimeofday	LINUX_2.6 (exported since Linux 3.15)
+__vdso_time	LINUX_2.6 (exported since Linux 3.15)
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS x86-64 functions
+.\" See linux/arch/x86/vdso/vdso.lds.S
+The table below lists the symbols exported by the vDSO.
+All of these symbols are also available without the "__vdso_" prefix, but
+you should ignore those and stick to the names below.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__vdso_clock_gettime	LINUX_2.6
+__vdso_getcpu	LINUX_2.6
+__vdso_gettimeofday	LINUX_2.6
+__vdso_time	LINUX_2.6
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS x86/x32 functions
+.\" See linux/arch/x86/vdso/vdso32.lds.S
+The table below lists the symbols exported by the vDSO.
+.if t \{\
+.ft CW
+\}
+.TS
+l l.
+symbol	version
+_
+__vdso_clock_gettime	LINUX_2.6
+__vdso_getcpu	LINUX_2.6
+__vdso_gettimeofday	LINUX_2.6
+__vdso_time	LINUX_2.6
+.TE
+.if t \{\
+.in
+.ft P
+\}
+.SS History
+The vDSO was originally just a single function\[em]the vsyscall.
+In older kernels, you might see that name
+in a process's memory map rather than "vdso".
+Over time, people realized that this mechanism
+was a great way to pass more functionality
+to user space, so it was reconceived as a vDSO in the current format.
+.SH SEE ALSO
+.BR syscalls (2),
+.BR getauxval (3),
+.BR proc (5)
+.P
+The documents, examples, and source code in the Linux source code tree:
+.P
+.in +4n
+.EX
+Documentation/ABI/stable/vdso
+Documentation/ia64/fsys.rst
+Documentation/vDSO/* (includes examples of using the vDSO)
+.P
+find arch/ \-iname \[aq]*vdso*\[aq] \-o \-iname \[aq]*gate*\[aq]
+.EE
+.in
diff --git a/man/man7/vsock.7 b/man/man7/vsock.7
new file mode 100644
index 000000000..fb30781e0
--- /dev/null
+++ b/man/man7/vsock.7
@@ -0,0 +1,232 @@
+.\" Copyright (C) 2018, Stefan Hajnoczi <stefanha@redhat.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH vsock 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+vsock \- Linux VSOCK address family
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <linux/vm_sockets.h>
+.P
+.IB stream_socket " = socket(AF_VSOCK, SOCK_STREAM, 0);"
+.IB datagram_socket " = socket(AF_VSOCK, SOCK_DGRAM, 0);"
+.fi
+.SH DESCRIPTION
+The VSOCK address family facilitates communication between virtual machines and
+the host they are running on.
+This address family is used by guest agents and
+hypervisor services that need a communications channel that is independent of
+virtual machine network configuration.
+.P
+Valid socket types are
+.B SOCK_STREAM
+and
+.BR SOCK_DGRAM .
+.B SOCK_STREAM
+provides connection-oriented byte streams with guaranteed, in-order delivery.
+.B SOCK_DGRAM
+provides a connectionless datagram packet service with best-effort delivery and
+best-effort ordering.
+Availability of these socket types is dependent on the
+underlying hypervisor.
+.P
+A new socket is created with
+.P
+.in +4n
+.EX
+socket(AF_VSOCK, socket_type, 0);
+.EE
+.in
+.P
+When a process wants to establish a connection, it calls
+.BR connect (2)
+with a given destination socket address.
+The socket is automatically bound to a free port if unbound.
+.P
+A process can listen for incoming connections by first binding to a socket
+address using
+.BR bind (2)
+and then calling
+.BR listen (2).
+.P
+Data is transmitted using the
+.BR send (2)
+or
+.BR write (2)
+families of system calls and data is received using the
+.BR recv (2)
+or
+.BR read (2)
+families of system calls.
+.SS Address format
+A socket address is defined as a combination of a 32-bit Context Identifier
+(CID) and a 32-bit port number.
+The CID identifies the source or destination,
+which is either a virtual machine or the host.
+The port number differentiates between multiple services running on
+a single machine.
+.P
+.in +4n
+.EX
+struct sockaddr_vm {
+    sa_family_t    svm_family;    /* Address family: AF_VSOCK */
+    unsigned short svm_reserved1;
+    unsigned int   svm_port;      /* Port # in host byte order */
+    unsigned int   svm_cid;       /* Address in host byte order */
+    unsigned char  svm_zero[sizeof(struct sockaddr) \-
+                            sizeof(sa_family_t) \-
+                            sizeof(unsigned short) \-
+                            sizeof(unsigned int) \-
+                            sizeof(unsigned int)];
+};
+.EE
+.in
+.P
+.I svm_family
+is always set to
+.BR AF_VSOCK .
+.I svm_reserved1
+is always set to 0.
+.I svm_port
+contains the port number in host byte order.
+The port numbers below 1024 are called
+.IR "privileged ports" .
+Only a process with the
+.B CAP_NET_BIND_SERVICE
+capability may
+.BR bind (2)
+to these port numbers.
+.I svm_zero
+must be zero-filled.
+.P
+There are several special addresses:
+.B VMADDR_CID_ANY
+(\-1U)
+means any address for binding;
+.B VMADDR_CID_HYPERVISOR
+(0) is reserved for services built into the hypervisor;
+.B VMADDR_CID_LOCAL
+(1) is the well-known address for local communication (loopback);
+.B VMADDR_CID_HOST
+(2)
+is the well-known address of the host.
+.P
+The special constant
+.B VMADDR_PORT_ANY
+(\-1U)
+means any port number for binding.
+.SS Live migration
+Sockets are affected by live migration of virtual machines.
+Connected
+.B SOCK_STREAM
+sockets become disconnected when the virtual machine migrates to a new host.
+Applications must reconnect when this happens.
+.P
+The local CID may change across live migration if the old CID is
+not available on the new host.
+Bound sockets are automatically updated to the new CID.
+.SS Ioctls
+The following ioctls are available on the
+.I /dev/vsock
+device.
+.TP
+.B IOCTL_VM_SOCKETS_GET_LOCAL_CID
+Get the CID of the local machine.
+The argument is a pointer to an
+.IR "unsigned int" .
+.IP
+.in +4n
+.EX
+ioctl(fd, IOCTL_VM_SOCKETS_GET_LOCAL_CID, &cid);
+.EE
+.in
+.IP
+Consider using
+.B VMADDR_CID_ANY
+when binding instead of getting the local CID with
+.BR IOCTL_VM_SOCKETS_GET_LOCAL_CID .
+.SS Local communication
+.B VMADDR_CID_LOCAL
+(1) directs packets to the same host that generated them.
+This is useful
+for testing applications on a single host and for debugging.
+.P
+The local CID obtained with
+.B IOCTL_VM_SOCKETS_GET_LOCAL_CID
+can be used for the same purpose, but it is preferable to use
+.BR VMADDR_CID_LOCAL .
+.SH ERRORS
+.TP
+.B EACCES
+Unable to bind to a privileged port without the
+.B CAP_NET_BIND_SERVICE
+capability.
+.TP
+.B EADDRINUSE
+Unable to bind to a port that is already in use.
+.TP
+.B EADDRNOTAVAIL
+Unable to find a free port for binding or unable to bind to a nonlocal CID.
+.TP
+.B EINVAL
+Invalid parameters.
+This includes:
+attempting to bind a socket that is already bound, providing an invalid struct
+.IR sockaddr_vm ,
+and other input validation errors.
+.TP
+.B ENOPROTOOPT
+Invalid socket option in
+.BR setsockopt (2)
+or
+.BR getsockopt (2).
+.TP
+.B ENOTCONN
+Unable to perform operation on an unconnected socket.
+.TP
+.B EOPNOTSUPP
+Operation not supported.
+This includes:
+the
+.B MSG_OOB
+flag that is not implemented for the
+.BR send (2)
+family of syscalls and
+.B MSG_PEEK
+for the
+.BR recv (2)
+family of syscalls.
+.TP
+.B EPROTONOSUPPORT
+Invalid socket protocol number.
+The protocol should always be 0.
+.TP
+.B ESOCKTNOSUPPORT
+Unsupported socket type in
+.BR socket (2).
+Only
+.B SOCK_STREAM
+and
+.B SOCK_DGRAM
+are valid.
+.SH VERSIONS
+Support for VMware (VMCI) has been available since Linux 3.9.
+KVM (virtio) is supported since Linux 4.8.
+Hyper-V is supported since Linux 4.14.
+.P
+.B VMADDR_CID_LOCAL
+is supported since Linux 5.6.
+.\" commit ef343b35d46667668a099655fca4a5b2e43a5dfe
+Local communication in the guest and on the host is available since Linux 5.6.
+Previous versions supported only local communication within a guest
+(not on the host), and with only some transports (VMCI and virtio).
+.SH SEE ALSO
+.BR bind (2),
+.BR connect (2),
+.BR listen (2),
+.BR recv (2),
+.BR send (2),
+.BR socket (2),
+.BR capabilities (7)
diff --git a/man/man7/x25.7 b/man/man7/x25.7
new file mode 100644
index 000000000..7e7123051
--- /dev/null
+++ b/man/man7/x25.7
@@ -0,0 +1,124 @@
+.\" SPDX-License-Identifier: Linux-man-pages-1-para
+.\"
+.\" This man page is Copyright (C) 1998 Heiner Eisen.
+.\"
+.\" $Id: x25.7,v 1.4 1999/05/18 10:35:12 freitag Exp $
+.\"
+.TH x25 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+x25
+\-
+ITU-T X.25 / ISO/IEC\~8208 protocol interface
+.SH SYNOPSIS
+.nf
+.B #include <sys/socket.h>
+.B #include <linux/x25.h>
+.P
+.IB x25_socket " = socket(AF_X25, SOCK_SEQPACKET, 0);"
+.fi
+.SH DESCRIPTION
+X25 sockets provide an interface to the X.25 packet layer protocol.
+This allows applications to
+communicate over a public X.25 data network as standardized by
+International Telecommunication Union's recommendation X.25
+(X.25 DTE-DCE mode).
+X25 sockets can also be used for communication
+without an intermediate X.25 network (X.25 DTE-DTE mode) as described
+in ISO/IEC\~8208.
+.P
+Message boundaries are preserved \[em] a
+.BR read (2)
+from a socket will
+retrieve the same chunk of data as output with the corresponding
+.BR write (2)
+to the peer socket.
+When necessary, the kernel takes care
+of segmenting and reassembling long messages by means of
+the X.25 M-bit.
+There is no hard-coded upper limit for the
+message size.
+However, reassembling of a long message might fail if
+there is a temporary lack of system resources or when other constraints
+(such as socket memory or buffer size limits) become effective.
+If that
+occurs, the X.25 connection will be reset.
+.SS Socket addresses
+The
+.B AF_X25
+socket address family uses the
+.I struct sockaddr_x25
+for representing network addresses as defined in ITU-T
+recommendation X.121.
+.P
+.in +4n
+.EX
+struct sockaddr_x25 {
+    sa_family_t sx25_family;    /* must be AF_X25 */
+    x25_address sx25_addr;      /* X.121 Address */
+};
+.EE
+.in
+.P
+.I sx25_addr
+contains a char array
+.I x25_addr[]
+to be interpreted as a null-terminated string.
+.I sx25_addr.x25_addr[]
+consists of up to 15 (not counting the terminating null byte) ASCII
+characters forming the X.121 address.
+Only the decimal digit characters from \[aq]0\[aq] to \[aq]9\[aq] are allowed.
+.SS Socket options
+The following X.25-specific socket options can be set by using
+.BR setsockopt (2)
+and read with
+.BR getsockopt (2)
+with the
+.I level
+argument set to
+.BR SOL_X25 .
+.TP
+.B X25_QBITINCL
+Controls whether the X.25 Q-bit (Qualified Data Bit) is accessible by the
+user.
+It expects an integer argument.
+If set to 0 (default),
+the Q-bit is never set for outgoing packets and the Q-bit of incoming
+packets is ignored.
+If set to 1, an additional first byte is prepended
+to each message read from or written to the socket.
+For data read from
+the socket, a 0 first byte indicates that the Q-bits of the corresponding
+incoming data packets were not set.
+A first byte with value 1 indicates
+that the Q-bit of the corresponding incoming data packets was set.
+If the first byte of the data written to the socket is 1, the Q-bit of the
+corresponding outgoing data packets will be set.
+If the first byte is 0,
+the Q-bit will not be set.
+.SH VERSIONS
+The AF_X25 protocol family is a new feature of Linux 2.2.
+.SH BUGS
+Plenty, as the X.25 PLP implementation is
+.BR CONFIG_EXPERIMENTAL .
+.P
+This man page is incomplete.
+.P
+There is no dedicated application programmer's header file yet;
+you need to include the kernel header file
+.IR <linux/x25.h> .
+.B CONFIG_EXPERIMENTAL
+might also imply that future versions of the
+interface are not binary compatible.
+.P
+X.25 N-Reset events are not propagated to the user process yet.
+Thus,
+if a reset occurred, data might be lost without notice.
+.SH SEE ALSO
+.BR socket (2),
+.BR socket (7)
+.P
+Jonathan Simon Naylor:
+\[lq]The Re-Analysis and Re-Implementation of X.25.\[rq]
+The URL is
+.UR ftp://ftp.pspt.fi\:/pub\:/ham\:/linux\:/ax25\:/x25doc.tgz
+.UE .
diff --git a/man/man7/xattr.7 b/man/man7/xattr.7
new file mode 100644
index 000000000..540179564
--- /dev/null
+++ b/man/man7/xattr.7
@@ -0,0 +1,180 @@
+.\" Extended attributes manual page
+.\"
+.\" Copyright (C) 2000, 2002, 2007  Andreas Gruenbacher <agruen@suse.de>
+.\" Copyright (C) 2001, 2002, 2004, 2007 Silicon Graphics, Inc.
+.\" All rights reserved.
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH xattr 7 (date) "Linux man-pages (unreleased)"
+.SH NAME
+xattr \- Extended attributes
+.SH DESCRIPTION
+Extended attributes are name:value pairs associated permanently with
+files and directories, similar to the environment strings associated
+with a process.
+An attribute may be defined or undefined.
+If it is defined, its value may be empty or non-empty.
+.P
+Extended attributes are extensions to the normal attributes which are
+associated with all inodes in the system (i.e., the
+.BR stat (2)
+data).
+They are often used to provide additional functionality
+to a filesystem\[em]for example, additional security features such as
+Access Control Lists (ACLs) may be implemented using extended attributes.
+.P
+Users with search access to a file or directory may use
+.BR listxattr (2)
+to retrieve a list of attribute names defined for that file or directory.
+.P
+Extended attributes are accessed as atomic objects.
+Reading
+.RB ( getxattr (2))
+retrieves the whole value of an attribute and stores it in a buffer.
+Writing
+.RB ( setxattr (2))
+replaces any previous value with the new value.
+.P
+Space consumed for extended attributes may be counted towards the disk quotas
+of the file owner and file group.
+.SS Extended attribute namespaces
+Attribute names are null-terminated strings.
+The attribute name is always specified in the fully qualified
+.I namespace.attribute
+form, for example,
+.IR user.mime_type ,
+.IR trusted.md5sum ,
+.IR system.posix_acl_access ,
+or
+.IR security.selinux .
+.P
+The namespace mechanism is used to define different classes of extended
+attributes.
+These different classes exist for several reasons;
+for example, the permissions
+and capabilities required for manipulating extended attributes of one
+namespace may differ to another.
+.P
+Currently, the
+.IR security ,
+.IR system ,
+.IR trusted ,
+and
+.I user
+extended attribute classes are defined as described below.
+Additional classes may be added in the future.
+.SS Extended security attributes
+The security attribute namespace is used by kernel security modules,
+such as Security Enhanced Linux, and also to implement file capabilities (see
+.BR capabilities (7)).
+Read and write access permissions to security attributes depend on the
+policy implemented for each security attribute by the security module.
+When no security module is loaded, all processes have read access to
+extended security attributes, and write access is limited to processes
+that have the
+.B CAP_SYS_ADMIN
+capability.
+.SS System extended attributes
+System extended attributes are used by the kernel to store system
+objects such as Access Control Lists.
+Read and write
+access permissions to system attributes depend on the policy implemented
+for each system attribute implemented by filesystems in the kernel.
+.SS Trusted extended attributes
+Trusted extended attributes are visible and accessible only to processes that
+have the
+.B CAP_SYS_ADMIN
+capability.
+Attributes in this class are used to implement mechanisms in user
+space (i.e., outside the kernel) which keep information in extended attributes
+to which ordinary processes should not have access.
+.SS User extended attributes
+User extended attributes may be assigned to files and directories for
+storing arbitrary additional information such as the mime type,
+character set or encoding of a file.
+The access permissions for user
+attributes are defined by the file permission bits:
+read permission is required to retrieve the attribute value,
+and writer permission is required to change it.
+.P
+The file permission bits of regular files and directories are
+interpreted differently from the file permission bits of special files
+and symbolic links.
+For regular files and directories the file
+permission bits define access to the file's contents, while for device special
+files they define access to the device described by the special file.
+The file permissions of symbolic links are not used in access checks.
+These differences would allow users to consume filesystem resources in
+a way not controllable by disk quotas for group or world writable
+special files and directories.
+.P
+For this reason,
+user extended attributes are allowed only for regular files and directories,
+and access to user extended attributes is restricted to the
+owner and to users with appropriate capabilities for directories with the
+sticky bit set (see the
+.BR chmod (1)
+manual page for an explanation of the sticky bit).
+.SS Filesystem differences
+The kernel and the filesystem may place limits on the maximum number
+and size of extended attributes that can be associated with a file.
+The VFS-imposed limits on attribute names and values are 255 bytes
+and 64\ kB, respectively.
+The list of attribute names that
+can be returned is also limited to 64\ kB
+(see BUGS in
+.BR listxattr (2)).
+.P
+Some filesystems, such as Reiserfs (and, historically, ext2 and ext3),
+require the filesystem to be mounted with the
+.B user_xattr
+mount option in order for user extended attributes to be used.
+.P
+In the current ext2, ext3, and ext4 filesystem implementations,
+the total bytes used by the names and values of all of a file's
+extended attributes must fit in a single filesystem block (1024, 2048
+or 4096 bytes, depending on the block size specified when the
+filesystem was created).
+.P
+In the Btrfs, XFS, and Reiserfs filesystem implementations, there is no
+practical limit on the number of extended attributes
+associated with a file, and the algorithms used to store extended
+attribute information on disk are scalable.
+.P
+In the JFS, XFS, and Reiserfs filesystem implementations,
+the limit on bytes used in an EA value is the ceiling imposed by the VFS.
+.P
+In the Btrfs filesystem implementation,
+the total bytes used for the name, value, and implementation overhead bytes
+is limited to the filesystem
+.I nodesize
+value (16\ kB by default).
+.SH STANDARDS
+Extended attributes are not specified in POSIX.1, but some other systems
+(e.g., the BSDs and Solaris) provide a similar feature.
+.SH NOTES
+Since the filesystems on which extended attributes are stored might also
+be used on architectures with a different byte order and machine word
+size, care should be taken to store attribute values in an
+architecture-independent format.
+.P
+This page was formerly named
+.BR attr (5).
+.\" .SH AUTHORS
+.\" Andreas Gruenbacher,
+.\" .RI < a.gruenbacher@bestbits.at >
+.\" and the SGI XFS development team,
+.\" .RI < linux-xfs@oss.sgi.com >.
+.SH SEE ALSO
+.BR attr (1),
+.BR getfattr (1),
+.BR setfattr (1),
+.BR getxattr (2),
+.BR ioctl_iflags (2),
+.BR listxattr (2),
+.BR removexattr (2),
+.BR setxattr (2),
+.BR acl (5),
+.BR capabilities (7),
+.BR selinux (8)
diff --git a/man/man8/iconvconfig.8 b/man/man8/iconvconfig.8
new file mode 100644
index 000000000..63c8b8d43
--- /dev/null
+++ b/man/man8/iconvconfig.8
@@ -0,0 +1,92 @@
+.\" Copyright (C) 2014 Marko Myllynen <myllynen@redhat.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.TH iconvconfig 8 (date) "Linux man-pages (unreleased)"
+.SH NAME
+iconvconfig \- create iconv module configuration cache
+.SH SYNOPSIS
+.B iconvconfig
+.RI [ options ]
+.RI [ directory ]...
+.SH DESCRIPTION
+The
+.BR iconv (3)
+function internally uses
+.I gconv
+modules to convert to and from a character set.
+A configuration file is used to determine the needed modules
+for a conversion.
+Loading and parsing such a configuration file would slow down
+programs that use
+.BR iconv (3),
+so a caching mechanism is employed.
+.P
+The
+.B iconvconfig
+program reads iconv module configuration files and writes
+a fast-loading gconv module configuration cache file.
+.P
+In addition to the system provided gconv modules, the user can specify
+custom gconv module directories with the environment variable
+.BR GCONV_PATH .
+However, iconv module configuration caching is used only when
+the environment variable
+.B GCONV_PATH
+is not set.
+.SH OPTIONS
+.TP
+.B "\-\-nostdlib"
+Do not search the system default gconv directory,
+only the directories provided on the command line.
+.TP
+.BI \-\-output= outputfile
+.TQ
+.BI \-o\~ outputfile
+Use
+.I outputfile
+for output instead of the system default cache location.
+.TP
+.BI \-\-prefix= pathname
+Set the prefix to be prepended to the system pathnames.
+See FILES, below.
+By default, the prefix is empty.
+Setting the prefix to
+.IR foo ,
+the gconv module configuration would be read from
+.I foo/usr/lib/gconv/gconv\-modules
+and the cache would be written to
+.IR foo/usr/lib/gconv/gconv\-modules.cache .
+.TP
+.B \-\-help
+.TQ
+.B \-?
+Print a usage summary and exit.
+.TP
+.B \-\-usage
+Print a short usage summary and exit.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Print the version number, license, and disclaimer of warranty for
+.BR iconv .
+.SH EXIT STATUS
+Zero on success, nonzero on errors.
+.SH FILES
+.TP
+.I /usr/lib/gconv
+Usual default gconv module path.
+.TP
+.I /usr/lib/gconv/gconv\-modules
+Usual system default gconv module configuration file.
+.TP
+.I /usr/lib/gconv/gconv\-modules.cache
+Usual system gconv module configuration cache.
+.P
+Depending on the architecture,
+the above files may instead be located at directories with the path prefix
+.IR /usr/lib64 .
+.SH SEE ALSO
+.BR iconv (1),
+.BR iconv (3)
diff --git a/man/man8/intro.8 b/man/man8/intro.8
new file mode 100644
index 000000000..bd0345de1
--- /dev/null
+++ b/man/man8/intro.8
@@ -0,0 +1,29 @@
+.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
+.\"         Fri Apr  2 11:32:09 MET DST 1993
+.\" and Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified Sat Jul 24 17:35:48 1993 by Rik Faith (faith@cs.unc.edu)
+.\" 2007-10-23 mtk: minor rewrites, and added paragraph on exit status
+.\"
+.TH intro 8 (date) "Linux man-pages (unreleased)"
+.SH NAME
+intro \- introduction to administration and privileged commands
+.SH DESCRIPTION
+Section 8 of the manual describes commands
+which either can be or are used only by the superuser,
+like system-administration commands, daemons,
+and hardware-related commands.
+.P
+As with the commands described in Section 1, the commands described
+in this section terminate with an exit status that indicates
+whether the command succeeded or failed.
+See
+.BR intro (1)
+for more information.
+.SH NOTES
+.SS Authors and copyright conditions
+Look at the header of the manual page source for the author(s) and copyright
+conditions.
+Note that these can be different from page to page!
diff --git a/man/man8/ld-linux.8 b/man/man8/ld-linux.8
new file mode 100644
index 000000000..c57562024
--- /dev/null
+++ b/man/man8/ld-linux.8
@@ -0,0 +1 @@
+.so man8/ld.so.8
diff --git a/man/man8/ld-linux.so.8 b/man/man8/ld-linux.so.8
new file mode 100644
index 000000000..c57562024
--- /dev/null
+++ b/man/man8/ld-linux.so.8
@@ -0,0 +1 @@
+.so man8/ld.so.8
diff --git a/man/man8/ld.so.8 b/man/man8/ld.so.8
new file mode 100644
index 000000000..fa75b7820
--- /dev/null
+++ b/man/man8/ld.so.8
@@ -0,0 +1,930 @@
+.\" %%%LICENSE_START(PUBLIC_DOMAIN)
+.\" This is in the public domain
+.\" %%%LICENSE_END
+.\" Various parts:
+.\" Copyright (C) 2007-9, 2013, 2016 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.TH ld.so 8 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ld.so, ld\-linux.so \- dynamic linker/loader
+.SH SYNOPSIS
+The dynamic linker can be run either indirectly by running some
+dynamically linked program or shared object
+(in which case no command-line options
+to the dynamic linker can be passed and, in the ELF case, the dynamic linker
+which is stored in the
+.B .interp
+section of the program is executed) or directly by running:
+.P
+.I /lib/ld\-linux.so.*
+[OPTIONS] [PROGRAM [ARGUMENTS]]
+.SH DESCRIPTION
+The programs
+.B ld.so
+and
+.B ld\-linux.so*
+find and load the shared objects (shared libraries) needed by a program,
+prepare the program to run, and then run it.
+.P
+Linux binaries require dynamic linking (linking at run time)
+unless the
+.B \-static
+option was given to
+.BR ld (1)
+during compilation.
+.P
+The program
+.B ld.so
+handles a.out binaries, a binary format used long ago.
+The program
+.B ld\-linux.so*
+(\fI/lib/ld\-linux.so.1\fP for libc5, \fI/lib/ld\-linux.so.2\fP for glibc2)
+handles binaries that are in the more modern ELF format.
+Both programs have the same behavior, and use the same
+support files and programs
+.RB ( ldd (1),
+.BR ldconfig (8),
+and
+.IR /etc/ld.so.conf ).
+.P
+When resolving shared object dependencies,
+the dynamic linker first inspects each dependency
+string to see if it contains a slash (this can occur if
+a shared object pathname containing slashes was specified at link time).
+If a slash is found, then the dependency string is interpreted as
+a (relative or absolute) pathname,
+and the shared object is loaded using that pathname.
+.P
+If a shared object dependency does not contain a slash,
+then it is searched for in the following order:
+.IP (1) 5
+Using the directories specified in the
+DT_RPATH dynamic section attribute
+of the binary if present and DT_RUNPATH attribute does not exist.
+Use of DT_RPATH is deprecated.
+.IP (2)
+Using the environment variable
+.BR LD_LIBRARY_PATH ,
+unless the executable is being run in secure-execution mode (see below),
+in which case this variable is ignored.
+.IP (3)
+Using the directories specified in the
+DT_RUNPATH dynamic section attribute
+of the binary if present.
+Such directories are searched only to
+find those objects required by DT_NEEDED (direct dependencies) entries
+and do not apply to those objects' children,
+which must themselves have their own DT_RUNPATH entries.
+This is unlike DT_RPATH, which is applied
+to searches for all children in the dependency tree.
+.IP (4)
+From the cache file
+.IR /etc/ld.so.cache ,
+which contains a compiled list of candidate shared objects previously found
+in the augmented library path.
+If, however, the binary was linked with the
+.B \-z nodefaultlib
+linker option, shared objects in the default paths are skipped.
+Shared objects installed in hardware capability directories (see below)
+are preferred to other shared objects.
+.IP (5)
+In the default path
+.IR /lib ,
+and then
+.IR /usr/lib .
+(On some 64-bit architectures, the default paths for 64-bit shared objects are
+.IR /lib64 ,
+and then
+.IR /usr/lib64 .)
+If the binary was linked with the
+.B \-z nodefaultlib
+linker option, this step is skipped.
+.\"
+.SS Dynamic string tokens
+In several places, the dynamic linker expands dynamic string tokens:
+.IP \[bu] 3
+In the environment variables
+.BR LD_LIBRARY_PATH ,
+.BR LD_PRELOAD ,
+and
+.BR LD_AUDIT ,
+.IP \[bu]
+inside the values of the dynamic section tags
+.BR DT_NEEDED ,
+.BR DT_RPATH ,
+.BR DT_RUNPATH ,
+.BR DT_AUDIT ,
+and
+.B DT_DEPAUDIT
+of ELF binaries,
+.IP \[bu]
+in the arguments to the
+.B ld.so
+command line options
+.BR \-\-audit ,
+.BR \-\-library\-path ,
+and
+.B \-\-preload
+(see below), and
+.IP \[bu]
+in the filename arguments to the
+.BR dlopen (3)
+and
+.BR dlmopen (3)
+functions.
+.P
+The substituted tokens are as follows:
+.TP
+.IR $ORIGIN " (or equivalently " ${ORIGIN} )
+This expands to
+the directory containing the program or shared object.
+Thus, an application located in
+.I somedir/app
+could be compiled with
+.IP
+.in +4n
+.EX
+gcc \-Wl,\-rpath,\[aq]$ORIGIN/../lib\[aq]
+.EE
+.in
+.IP
+so that it finds an associated shared object in
+.I somedir/lib
+no matter where
+.I somedir
+is located in the directory hierarchy.
+This facilitates the creation of "turn-key" applications that
+do not need to be installed into special directories,
+but can instead be unpacked into any directory
+and still find their own shared objects.
+.TP
+.IR $LIB " (or equivalently " ${LIB} )
+This expands to
+.I lib
+or
+.I lib64
+depending on the architecture
+(e.g., on x86-64, it expands to
+.I lib64
+and
+on x86-32, it expands to
+.IR lib ).
+.TP
+.IR $PLATFORM " (or equivalently " ${PLATFORM} )
+This expands to a string corresponding to the processor type
+of the host system (e.g., "x86_64").
+On some architectures, the Linux kernel doesn't provide a platform
+string to the dynamic linker.
+The value of this string is taken from the
+.B AT_PLATFORM
+value in the auxiliary vector (see
+.BR getauxval (3)).
+.\" To get an idea of the places that $PLATFORM would match,
+.\" look at the output of the following:
+.\"
+.\"     mkdir /tmp/d
+.\"     LD_LIBRARY_PATH=/tmp/d strace -e open /bin/date 2>&1 | grep /tmp/d
+.\"
+.\" ld.so lets names be abbreviated, so $O will work for $ORIGIN;
+.\" Don't do this!!
+.P
+Note that the dynamic string tokens have to be quoted properly when
+set from a shell,
+to prevent their expansion as shell or environment variables.
+.SH OPTIONS
+.TP
+.BR \-\-argv0 " \fIstring\fP (since glibc 2.33)"
+Set
+.I argv[0]
+to the value
+.I string
+before running the program.
+.TP
+.BI \-\-audit " list"
+Use objects named in
+.I list
+as auditors.
+The objects in
+.I list
+are delimited by colons.
+.TP
+.BI \-\-glibc-hwcaps-mask " list"
+only search built-in subdirectories if in
+.IR list .
+.TP
+.BI \-\-glibc-hwcaps-prepend " list"
+Search glibc-hwcaps subdirectories in
+.IR list .
+.TP
+.B \-\-inhibit\-cache
+Do not use
+.IR /etc/ld.so.cache .
+.TP
+.BI \-\-library\-path " path"
+Use
+.I path
+instead of
+.B LD_LIBRARY_PATH
+environment variable setting (see below).
+The names
+.IR ORIGIN ,
+.IR LIB ,
+and
+.I PLATFORM
+are interpreted as for the
+.B LD_LIBRARY_PATH
+environment variable.
+.TP
+.BI \-\-inhibit\-rpath " list"
+Ignore RPATH and RUNPATH information in object names in
+.IR list .
+This option is ignored when running in secure-execution mode (see below).
+The objects in
+.I list
+are delimited by colons or spaces.
+.TP
+.B \-\-list
+List all dependencies and how they are resolved.
+.TP
+.BR \-\-list\-diagnostics " (since glibc 2.33)"
+Print system diagnostic information in a machine-readable format,
+such as some internal loader variables,
+the auxiliary vector
+(see
+.BR getauxval (3)),
+and the environment variables.
+On some architectures,
+the command might print additional information
+(like the cpu features used in GNU indirect function selection on x86).
+.BR \-\-list\-tunables " (since glibc 2.33)"
+Print the names and values of all tunables,
+along with the minimum and maximum allowed values.
+.TP
+.BR \-\-preload " \fIlist\fP (since glibc 2.30)"
+Preload the objects specified in
+.IR list .
+The objects in
+.I list
+are delimited by colons or spaces.
+The objects are preloaded as explained in the description of the
+.B LD_PRELOAD
+environment variable below.
+.IP
+By contrast with
+.BR LD_PRELOAD ,
+the
+.B \-\-preload
+option provides a way to perform preloading for a single executable
+without affecting preloading performed in any child process that executes
+a new program.
+.TP
+.B \-\-verify
+Verify that program is dynamically linked and this dynamic linker can handle
+it.
+.SH ENVIRONMENT
+Various environment variables influence the operation of the dynamic linker.
+.\"
+.SS Secure-execution mode
+For security reasons,
+if the dynamic linker determines that a binary should be
+run in secure-execution mode,
+the effects of some environment variables are voided or modified,
+and furthermore those environment variables are stripped from the environment,
+so that the program does not even see the definitions.
+Some of these environment variables affect the operation of
+the dynamic linker itself, and are described below.
+Other environment variables treated in this way include:
+.BR GCONV_PATH ,
+.BR GETCONF_DIR ,
+.BR HOSTALIASES ,
+.BR LOCALDOMAIN ,
+.BR LD_AUDIT ,
+.BR LD_DEBUG ,
+.BR LD_DEBUG_OUTPUT ,
+.BR LD_DYNAMIC_WEAK ,
+.BR LD_HWCAP_MASK ,
+.BR LD_LIBRARY_PATH ,
+.BR LD_ORIGIN_PATH ,
+.BR LD_PRELOAD ,
+.BR LD_PROFILE ,
+.BR LD_SHOW_AUXV ,
+.BR LOCALDOMAIN ,
+.BR LOCPATH ,
+.BR MALLOC_TRACE ,
+.BR NIS_PATH ,
+.BR NLSPATH ,
+.BR RESOLV_HOST_CONF ,
+.BR RES_OPTIONS ,
+.BR TMPDIR ,
+and
+.BR TZDIR .
+.P
+A binary is executed in secure-execution mode if the
+.B AT_SECURE
+entry in the auxiliary vector (see
+.BR getauxval (3))
+has a nonzero value.
+This entry may have a nonzero value for various reasons, including:
+.IP \[bu] 3
+The process's real and effective user IDs differ,
+or the real and effective group IDs differ.
+This typically occurs as a result of executing
+a set-user-ID or set-group-ID program.
+.IP \[bu]
+A process with a non-root user ID executed a binary that
+conferred capabilities to the process.
+.IP \[bu]
+A nonzero value may have been set by a Linux Security Module.
+.\"
+.SS Environment variables
+Among the more important environment variables are the following:
+.TP
+.BR LD_ASSUME_KERNEL " (from glibc 2.2.3 to glibc 2.36)"
+Each shared object can inform the dynamic linker of the minimum kernel ABI
+version that it requires.
+(This requirement is encoded in an ELF note section that is viewable via
+.I readelf\~\-n
+as a section labeled
+.BR NT_GNU_ABI_TAG .)
+At run time,
+the dynamic linker determines the ABI version of the running kernel and
+will reject loading shared objects that specify minimum ABI versions
+that exceed that ABI version.
+.IP
+.B LD_ASSUME_KERNEL
+can be used to
+cause the dynamic linker to assume that it is running on a system with
+a different kernel ABI version.
+For example, the following command line causes the
+dynamic linker to assume it is running on Linux 2.2.5 when loading
+the shared objects required by
+.IR myprog :
+.IP
+.in +4n
+.EX
+$ \fBLD_ASSUME_KERNEL=2.2.5 ./myprog\fP
+.EE
+.in
+.IP
+On systems that provide multiple versions of a shared object
+(in different directories in the search path) that have
+different minimum kernel ABI version requirements,
+.B LD_ASSUME_KERNEL
+can be used to select the version of the object that is used
+(dependent on the directory search order).
+.IP
+Historically, the most common use of the
+.B LD_ASSUME_KERNEL
+feature was to manually select the older
+LinuxThreads POSIX threads implementation on systems that provided both
+LinuxThreads and NPTL
+(which latter was typically the default on such systems);
+see
+.BR pthreads (7).
+.TP
+.BR LD_BIND_NOW " (since glibc 2.1.1)"
+If set to a nonempty string,
+causes the dynamic linker to resolve all symbols
+at program startup instead of deferring function call resolution to the point
+when they are first referenced.
+This is useful when using a debugger.
+.TP
+.B LD_LIBRARY_PATH
+A list of directories in which to search for
+ELF libraries at execution time.
+The items in the list are separated by either colons or semicolons,
+and there is no support for escaping either separator.
+A zero-length directory name indicates the current working directory.
+.IP
+This variable is ignored in secure-execution mode.
+.IP
+Within the pathnames specified in
+.BR LD_LIBRARY_PATH ,
+the dynamic linker expands the tokens
+.IR $ORIGIN ,
+.IR $LIB ,
+and
+.I $PLATFORM
+(or the versions using curly braces around the names)
+as described above in
+.IR "Dynamic string tokens" .
+Thus, for example,
+the following would cause a library to be searched for in either the
+.I lib
+or
+.I lib64
+subdirectory below the directory containing the program to be executed:
+.IP
+.in +4n
+.EX
+$ \fBLD_LIBRARY_PATH=\[aq]$ORIGIN/$LIB\[aq] prog\fP
+.EE
+.in
+.IP
+(Note the use of single quotes, which prevent expansion of
+.I $ORIGIN
+and
+.I $LIB
+as shell variables!)
+.TP
+.B LD_PRELOAD
+A list of additional, user-specified, ELF shared
+objects to be loaded before all others.
+This feature can be used to selectively override functions
+in other shared objects.
+.IP
+The items of the list can be separated by spaces or colons,
+and there is no support for escaping either separator.
+The objects are searched for using the rules given under DESCRIPTION.
+Objects are searched for and added to the link map in the left-to-right
+order specified in the list.
+.IP
+In secure-execution mode,
+preload pathnames containing slashes are ignored.
+Furthermore, shared objects are preloaded only
+from the standard search directories and only
+if they have set-user-ID mode bit enabled (which is not typical).
+.IP
+Within the names specified in the
+.B LD_PRELOAD
+list, the dynamic linker understands the tokens
+.IR $ORIGIN ,
+.IR $LIB ,
+and
+.I $PLATFORM
+(or the versions using curly braces around the names)
+as described above in
+.IR "Dynamic string tokens" .
+(See also the discussion of quoting under the description of
+.BR LD_LIBRARY_PATH .)
+.\" Tested with the following:
+.\"
+.\"	LD_PRELOAD='$LIB/libmod.so' LD_LIBRARY_PATH=. ./prog
+.\"
+.\" which will preload the libmod.so in 'lib' or 'lib64', using it
+.\" in preference to the version in '.'.
+.IP
+There are various methods of specifying libraries to be preloaded,
+and these are handled in the following order:
+.RS
+.IP (1) 5
+The
+.B LD_PRELOAD
+environment variable.
+.IP (2)
+The
+.B \-\-preload
+command-line option when invoking the dynamic linker directly.
+.IP (3)
+The
+.I /etc/ld.so.preload
+file (described below).
+.RE
+.TP
+.B LD_TRACE_LOADED_OBJECTS
+If set (to any value), causes the program to list its dynamic
+dependencies, as if run by
+.BR ldd (1),
+instead of running normally.
+.P
+Then there are lots of more or less obscure variables,
+many obsolete or only for internal use.
+.TP
+.BR LD_AUDIT " (since glibc 2.4)"
+A list of user-specified, ELF shared objects
+to be loaded before all others in a separate linker namespace
+(i.e., one that does not intrude upon the normal symbol bindings that
+would occur in the process)
+These objects can be used to audit the operation of the dynamic linker.
+The items in the list are colon-separated,
+and there is no support for escaping the separator.
+.IP
+.B LD_AUDIT
+is ignored in secure-execution mode.
+.IP
+The dynamic linker will notify the audit
+shared objects at so-called auditing checkpoints\[em]for example,
+loading a new shared object, resolving a symbol,
+or calling a symbol from another shared object\[em]by
+calling an appropriate function within the audit shared object.
+For details, see
+.BR rtld\-audit (7).
+The auditing interface is largely compatible with that provided on Solaris,
+as described in its
+.IR "Linker and Libraries Guide" ,
+in the chapter
+.IR "Runtime Linker Auditing Interface" .
+.IP
+Within the names specified in the
+.B LD_AUDIT
+list, the dynamic linker understands the tokens
+.IR $ORIGIN ,
+.IR $LIB ,
+and
+.I $PLATFORM
+(or the versions using curly braces around the names)
+as described above in
+.IR "Dynamic string tokens" .
+(See also the discussion of quoting under the description of
+.BR LD_LIBRARY_PATH .)
+.IP
+Since glibc 2.13,
+.\" commit 8e9f92e9d5d7737afdacf79b76d98c4c42980508
+in secure-execution mode,
+names in the audit list that contain slashes are ignored,
+and only shared objects in the standard search directories that
+have the set-user-ID mode bit enabled are loaded.
+.TP
+.BR LD_BIND_NOT " (since glibc 2.1.95)"
+If this environment variable is set to a nonempty string,
+do not update the GOT (global offset table) and PLT (procedure linkage table)
+after resolving a function symbol.
+By combining the use of this variable with
+.B LD_DEBUG
+(with the categories
+.I bindings
+and
+.IR symbols ),
+one can observe all run-time function bindings.
+.TP
+.BR LD_DEBUG " (since glibc 2.1)"
+Output verbose debugging information about operation of the dynamic linker.
+The content of this variable is one of more of the following categories,
+separated by colons, commas, or (if the value is quoted) spaces:
+.RS
+.TP 12
+.I help
+Specifying
+.I help
+in the value of this variable does not run the specified program,
+and displays a help message about which categories can be specified in this
+environment variable.
+.TP
+.I all
+Print all debugging information (except
+.I statistics
+and
+.IR unused ;
+see below).
+.TP
+.I bindings
+Display information about which definition each symbol is bound to.
+.TP
+.I files
+Display progress for input file.
+.TP
+.I libs
+Display library search paths.
+.TP
+.I reloc
+Display relocation processing.
+.TP
+.I scopes
+Display scope information.
+.TP
+.I statistics
+Display relocation statistics.
+.TP
+.I symbols
+Display search paths for each symbol look-up.
+.TP
+.I unused
+Determine unused DSOs.
+.TP
+.I versions
+Display version dependencies.
+.RE
+.IP
+Since glibc 2.3.4,
+.B LD_DEBUG
+is ignored in secure-execution mode, unless the file
+.I /etc/suid\-debug
+exists (the content of the file is irrelevant).
+.TP
+.BR LD_DEBUG_OUTPUT " (since glibc 2.1)"
+By default,
+.B LD_DEBUG
+output is written to standard error.
+If
+.B LD_DEBUG_OUTPUT
+is defined, then output is written to the pathname specified by its value,
+with the suffix "." (dot) followed by the process ID appended to the pathname.
+.IP
+.B LD_DEBUG_OUTPUT
+is ignored in secure-execution mode.
+.TP
+.BR LD_DYNAMIC_WEAK " (since glibc 2.1.91)"
+By default, when searching shared libraries to resolve a symbol reference,
+the dynamic linker will resolve to the first definition it finds.
+.IP
+Old glibc versions (before glibc 2.2), provided a different behavior:
+if the linker found a symbol that was weak,
+it would remember that symbol and
+keep searching in the remaining shared libraries.
+If it subsequently found a strong definition of the same symbol,
+then it would instead use that definition.
+(If no further symbol was found,
+then the dynamic linker would use the weak symbol that it initially found.)
+.IP
+The old glibc behavior was nonstandard.
+(Standard practice is that the distinction between
+weak and strong symbols should have effect only at static link time.)
+In glibc 2.2,
+.\" More precisely 2.1.92
+.\" See weak handling
+.\"     https://www.sourceware.org/ml/libc-hacker/2000-06/msg00029.html
+.\"     To: GNU libc hacker <libc-hacker at sourceware dot cygnus dot com>
+.\"     Subject: weak handling
+.\"     From: Ulrich Drepper <drepper at redhat dot com>
+.\"     Date: 07 Jun 2000 20:08:12 -0700
+.\"     Reply-To: drepper at cygnus dot com (Ulrich Drepper)
+the dynamic linker was modified to provide the current behavior
+(which was the behavior that was provided by most other implementations
+at that time).
+.IP
+Defining the
+.B LD_DYNAMIC_WEAK
+environment variable (with any value) provides
+the old (nonstandard) glibc behavior,
+whereby a weak symbol in one shared library may be overridden by
+a strong symbol subsequently discovered in another shared library.
+(Note that even when this variable is set,
+a strong symbol in a shared library will not override
+a weak definition of the same symbol in the main program.)
+.IP
+Since glibc 2.3.4,
+.B LD_DYNAMIC_WEAK
+is ignored in secure-execution mode.
+.TP
+.BR LD_HWCAP_MASK " (from glibc 2.1 to glibc 2.38)"
+Mask for hardware capabilities.
+Since glibc 2.26,
+the option might be ignored
+if glibc does not support tunables.
+.TP
+.BR LD_ORIGIN_PATH " (since glibc 2.1)"
+Path where the binary is found.
+.\" Used only if $ORIGIN can't be determined by normal means
+.\" (from the origin path saved at load time, or from /proc/self/exe)?
+.IP
+Since glibc 2.4,
+.B LD_ORIGIN_PATH
+is ignored in secure-execution mode.
+.TP
+.BR LD_POINTER_GUARD " (from glibc 2.4 to glibc 2.22)"
+Set to 0 to disable pointer guarding.
+Any other value enables pointer guarding, which is also the default.
+Pointer guarding is a security mechanism whereby some pointers to code
+stored in writable program memory (return addresses saved by
+.BR setjmp (3)
+or function pointers used by various glibc internals) are mangled
+semi-randomly to make it more difficult for an attacker to hijack
+the pointers for use in the event of a buffer overrun or
+stack-smashing attack.
+Since glibc 2.23,
+.\" commit a014cecd82b71b70a6a843e250e06b541ad524f7
+.B LD_POINTER_GUARD
+can no longer be used to disable pointer guarding,
+which is now always enabled.
+.TP
+.BR LD_PROFILE " (since glibc 2.1)"
+The name of a (single) shared object to be profiled,
+specified either as a pathname or a soname.
+Profiling output is appended to the file whose name is:
+.RI \%$LD_PROFILE_OUTPUT /\: $LD_PROFILE .profile .
+.IP
+Since glibc 2.2.5,
+.B LD_PROFILE
+uses a different default path in secure-execution mode.
+.TP
+.BR LD_PROFILE_OUTPUT " (since glibc 2.1)"
+Directory where
+.B LD_PROFILE
+output should be written.
+If this variable is not defined, or is defined as an empty string,
+then the default is
+.IR /var/tmp .
+.IP
+.B LD_PROFILE_OUTPUT
+is ignored in secure-execution mode; instead
+.I /var/profile
+is always used.
+.TP
+.BR LD_SHOW_AUXV " (since glibc 2.1)"
+If this environment variable is defined (with any value),
+show the auxiliary array passed up from the kernel (see also
+.BR getauxval (3)).
+.IP
+Since glibc 2.3.4,
+.B LD_SHOW_AUXV
+is ignored in secure-execution mode.
+.TP
+.BR LD_TRACE_PRELINKING " (from glibc 2.4 to glibc 2.35)"
+If this environment variable is defined,
+trace prelinking of the object whose name is assigned to
+this environment variable.
+(Use
+.BR ldd (1)
+to get a list of the objects that might be traced.)
+If the object name is not recognized,
+.\" (This is what seems to happen, from experimenting)
+then all prelinking activity is traced.
+.TP
+.BR LD_USE_LOAD_BIAS " (from glibc 2.3.3 to glibc 2.35)"
+.\" http://sources.redhat.com/ml/libc-hacker/2003-11/msg00127.html
+.\" Subject: [PATCH] Support LD_USE_LOAD_BIAS
+.\" Jakub Jelinek
+By default (i.e., if this variable is not defined),
+executables and prelinked
+shared objects will honor base addresses of their dependent shared objects
+and (nonprelinked) position-independent executables (PIEs)
+and other shared objects will not honor them.
+If
+.B LD_USE_LOAD_BIAS
+is defined with the value 1, both executables and PIEs
+will honor the base addresses.
+If
+.B LD_USE_LOAD_BIAS
+is defined with the value 0,
+neither executables nor PIEs will honor the base addresses.
+.IP
+Since glibc 2.3.3, this variable is ignored in secure-execution mode.
+.TP
+.BR LD_VERBOSE " (since glibc 2.1)"
+If set to a nonempty string,
+output symbol versioning information about the
+program if the
+.B LD_TRACE_LOADED_OBJECTS
+environment variable has been set.
+.TP
+.BR LD_WARN " (since glibc 2.1.3)"
+If set to a nonempty string, warn about unresolved symbols.
+.TP
+.BR LD_PREFER_MAP_32BIT_EXEC " (x86-64 only; since glibc 2.23)"
+According to the Intel Silvermont software optimization guide, for 64-bit
+applications, branch prediction performance can be negatively impacted
+when the target of a branch is more than 4\ GB away from the branch.
+If this environment variable is set (to any value),
+the dynamic linker
+will first try to map executable pages using the
+.BR mmap (2)
+.B MAP_32BIT
+flag, and fall back to mapping without that flag if that attempt fails.
+NB: MAP_32BIT will map to the low 2\ GB (not 4\ GB) of the address space.
+.IP
+Because
+.B MAP_32BIT
+reduces the address range available for address space layout
+randomization (ASLR),
+.B LD_PREFER_MAP_32BIT_EXEC
+is always disabled in secure-execution mode.
+.SH FILES
+.TP
+.I /lib/ld.so
+a.out dynamic linker/loader
+.TP
+.IR /lib/ld\-linux.so. { 1 , 2 }
+ELF dynamic linker/loader
+.TP
+.I /etc/ld.so.cache
+File containing a compiled list of directories in which to search for
+shared objects and an ordered list of candidate shared objects.
+See
+.BR ldconfig (8).
+.TP
+.I /etc/ld.so.preload
+File containing a whitespace-separated list of ELF shared objects to
+be loaded before the program.
+See the discussion of
+.B LD_PRELOAD
+above.
+If both
+.B LD_PRELOAD
+and
+.I /etc/ld.so.preload
+are employed, the libraries specified by
+.B LD_PRELOAD
+are preloaded first.
+.I /etc/ld.so.preload
+has a system-wide effect,
+causing the specified libraries to be preloaded for
+all programs that are executed on the system.
+(This is usually undesirable,
+and is typically employed only as an emergency remedy, for example,
+as a temporary workaround to a library misconfiguration issue.)
+.TP
+.I lib*.so*
+shared objects
+.SH NOTES
+.SS Legacy Hardware capabilities (from glibc 2.5 to glibc 2.37)
+Some shared objects are compiled using hardware-specific instructions which do
+not exist on every CPU.
+Such objects should be installed in directories whose names define the
+required hardware capabilities, such as
+.IR /usr/lib/sse2/ .
+The dynamic linker checks these directories against the hardware of the
+machine and selects the most suitable version of a given shared object.
+Hardware capability directories can be cascaded to combine CPU features.
+The list of supported hardware capability names depends on the CPU.
+The following names are currently recognized:
+.\" Presumably, this info comes from sysdeps/i386/dl-procinfo.c and
+.\" similar files
+.TP
+.B Alpha
+ev4, ev5, ev56, ev6, ev67
+.TP
+.B MIPS
+loongson2e, loongson2f, octeon, octeon2
+.TP
+.B PowerPC
+4xxmac, altivec, arch_2_05, arch_2_06, booke, cellbe, dfp, efpdouble, efpsingle,
+fpu, ic_snoop, mmu, notb, pa6t, power4, power5, power5+, power6x, ppc32, ppc601,
+ppc64, smt, spe, ucache, vsx
+.TP
+.B SPARC
+flush, muldiv, stbar, swap, ultra3, v9, v9v, v9v2
+.TP
+.B s390
+dfp, eimm, esan3, etf3enh, g5, highgprs, hpage, ldisp, msa, stfle,
+z900, z990, z9-109, z10, zarch
+.TP
+.B x86 (32-bit only)
+acpi, apic, clflush, cmov, cx8, dts, fxsr, ht, i386, i486, i586, i686, mca, mmx,
+mtrr, pat, pbe, pge, pn, pse36, sep, ss, sse, sse2, tm
+.P
+The legacy hardware capabilities support has the drawback that
+each new feature added grows the search path exponentially,
+because it has to be added to
+every combination of the other existing features.
+.P
+For instance, on x86 32-bit,
+if the hardware supports
+.B i686
+and
+.BR sse2 ,
+the resulting search path will be
+.BR i686/sse2:i686:sse2:. .
+A new capability
+.B newcap
+will set the search path to
+.BR newcap/i686/sse2:newcap/i686:newcap/sse2:newcap:i686/sse2:i686:sse2: .
+.\"
+.SS glibc Hardware capabilities (from glibc 2.33)
+.TP
+.\" The initial discussion on various pitfalls of the old scheme is
+.\" <https://sourceware.org/pipermail/libc-alpha/2020-May/113757.html>
+.\" and the patchset that proposes the glibc-hwcap support is
+.\" <https://sourceware.org/pipermail/libc-alpha/2020-June/115250.html>
+glibc 2.33 added a new hardware capability scheme,
+where under each CPU architecture,
+certain levels can be defined,
+grouping support for certain features or special instructions.
+Each architecture level has
+a fixed set of paths that it adds to the dynamic linker search list,
+depending on the hardware of the machine.
+Since each new architecture level is
+not combined with previously existing ones,
+the new scheme does not have the drawback of
+growing the dynamic linker search list uncontrollably.
+.P
+For instance, on x86 64-bit,
+if the hardware supports
+.B x86_64-v3
+(for instance Intel Haswell or AMD Excavator),
+the resulting search path will be
+.B glibc-hwcaps/x86-64-v3:glibc-hwcaps/x86-64-v2:.
+.\" The x86_64 architectures levels are defined the official ABI:
+.\" <https://gitlab.com/x86-psABIs/x86-64-ABI/-/blob/master/x86-64-ABI/low-level-sys-info.tex>
+.\" The PowerPC and s390x are glibc defined ones based on chip
+.\" support (which maps to ISA levels).
+The following paths are currently supported, in priority order.
+.TP
+.B PowerPC (64-bit little-endian only)
+power10, power9
+.TP
+.B s390 (64-bit only)
+z16, z15, z14, z13
+.TP
+.B x86 (64-bit only)
+x86-64-v4, x86-64-v3, x86-64-v2
+.P
+glibc 2.37 removed support for the legacy hardware capabilities.
+.\"
+.SH SEE ALSO
+.BR ld (1),
+.BR ldd (1),
+.BR pldd (1),
+.BR sprof (1),
+.BR dlopen (3),
+.BR getauxval (3),
+.BR elf (5),
+.BR capabilities (7),
+.BR rtld\-audit (7),
+.BR ldconfig (8),
+.BR sln (8)
+.\" .SH AUTHORS
+.\" ld.so: David Engel, Eric Youngdale, Peter MacDonald, Hongjiu Lu, Linus
+.\"  Torvalds, Lars Wirzenius and Mitch D'Souza
+.\" ld\-linux.so: Roland McGrath, Ulrich Drepper and others.
+.\"
+.\" In the above, (libc5) stands for David Engel's ld.so/ld\-linux.so.
diff --git a/man/man8/ldconfig.8 b/man/man8/ldconfig.8
new file mode 100644
index 000000000..f9211caf8
--- /dev/null
+++ b/man/man8/ldconfig.8
@@ -0,0 +1,204 @@
+.\" Copyright 1999 SuSE GmbH Nuernberg, Germany
+.\" Author: Thorsten Kukuk <kukuk@suse.de>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" Modified, 6 May 2002, Michael Kerrisk, <mtk.manpages@gmail.com>
+.\"   Change listed order of /usr/lib and /lib
+.TH ldconfig 8 (date) "Linux man-pages (unreleased)"
+.SH NAME
+ldconfig \- configure dynamic linker run-time bindings
+.SH SYNOPSIS
+.SY /sbin/ldconfig
+.\" TODO?: -c, --format, -i, --ignore-aux-cache, --print-cache,
+.\" --verbose, -V, --version, -?, --help, --usage
+.RB [ \-nNvVX ]
+.RB [ \-C\~\c
+.IR cache ]
+.RB [ \-f\~\c
+.IR conf ]
+.RB [ \-r\~\c
+.IR root ]
+.IR directory \~.\|.\|.
+.YS
+.SY /sbin/ldconfig
+.B \-l
+.RB [ \-v ]
+.IR library \~.\|.\|.
+.YS
+.SY /sbin/ldconfig
+.B \-p
+.YS
+.SH DESCRIPTION
+.B \%ldconfig
+creates the necessary links and cache to the most recent shared
+libraries found in the directories specified on the command line,
+in the file
+.IR /etc/ld.so.conf ,
+and in the trusted directories,
+.I /lib
+and
+.IR /usr/lib .
+On some 64-bit architectures such as x86-64,
+.I /lib
+and
+.I /usr/lib
+are the trusted directories for 32-bit libraries,
+while
+.I /lib64
+and
+.I /usr/lib64
+are used for 64-bit libraries.
+.P
+The cache is used by the run-time linker,
+.I ld.so
+or
+.IR ld\-linux.so .
+.B \%ldconfig
+checks the header and filenames of the libraries it encounters when
+determining which versions should have their links updated.
+.\" Support for libc4 and libc5 dropped in
+.\" 8ee878592c4a642937152c8308b8faef86bcfc40 (2022-07-14) as "obsolete
+.\" for over twenty years".
+.B \%ldconfig
+should normally be run by the superuser as it may require write
+permission on some root owned directories and files.
+.P
+.B \%ldconfig
+will look only at files that are named
+.I lib*.so*
+(for regular shared objects) or
+.I ld\-*.so*
+(for the dynamic loader itself).
+Other files will be ignored.
+Also,
+.B \%ldconfig
+expects a certain pattern to how the symbolic links are set up,
+like this example,
+where the middle file
+.RB ( libfoo.so.1
+here) is the SONAME for the library:
+.P
+.in +4n
+.EX
+libfoo.so \-> libfoo.so.1 \-> libfoo.so.1.12
+.EE
+.in
+.P
+Failure to follow this pattern may result in compatibility issues
+after an upgrade.
+.SH OPTIONS
+.TP
+.BI \-\-format= fmt
+.TQ
+.BI \-c\~ fmt
+(Since glibc 2.2)
+.\" commit 45eca4d141c047950db48c69c8941163d0a61fcd
+Use cache format
+.IR fmt ,
+which is one of
+.BR old ,
+.BR new ,
+or
+.BR \%compat .
+Since glibc 2.32,
+the default is
+.BR new .
+.\" commit cad64f778aced84efdaa04ae64f8737b86f063ab
+Before that,
+it was
+.BR \%compat .
+.TP
+.BI \-C\~ cache
+Use
+.I cache
+instead of
+.IR /etc/ld.so.cache .
+.TP
+.BI \-f\~ conf
+Use
+.I conf
+instead of
+.IR /etc/ld.so.conf .
+.TP
+.B \-\-ignore\-aux\-cache
+.TQ
+.B \-i
+(Since glibc 2.7)
+.\" commit 27d9ffda17df4d2388687afd12897774fde39bcc
+Ignore auxiliary cache file.
+.TP
+.B \-l
+(Since glibc 2.2)
+Interpret each operand as a library name and configure its links.
+Intended for use only by experts.
+.TP
+.B \-n
+Process only the directories specified on the command line;
+don't process the trusted directories,
+nor those specified in
+.IR /etc/ld.so.conf .
+Implies
+.BR \-N .
+.TP
+.B \-N
+Don't rebuild the cache.
+Unless
+.B \-X
+is also specified,
+links are still updated.
+.TP
+.B \-\-print\-cache
+.TQ
+.B \-p
+Print the lists of directories and candidate libraries stored in
+the current cache.
+.TP
+.BI \-r\~ root
+Change to and use
+.I root
+as the root directory.
+.TP
+.B \-\-verbose
+.TQ
+.B \-v
+Verbose mode.
+Print current version number,
+the name of each directory as it is scanned,
+and any links that are created.
+Overrides quiet mode.
+.TP
+.B \-\-version
+.TQ
+.B \-V
+Print program version.
+.TP
+.B \-X
+Don't update links.
+Unless
+.B \-N
+is also specified,
+the cache is still rebuilt.
+.SH FILES
+.\" FIXME Since glibc-2.3.4, "include" directives are supported in ld.so.conf
+.\"
+.\" FIXME Since glibc-2.4, "hwcap" directives are supported in ld.so.conf
+.PD 0
+.TP
+.I /lib/ld.so
+is the run-time linker/loader.
+.TP
+.I /etc/ld.so.conf
+contains a list of directories,
+one per line,
+in which to search for libraries.
+.TP
+.I /etc/ld.so.cache
+contains an ordered list of libraries found in the directories
+specified in
+.IR /etc/ld.so.conf ,
+as well as those found in the trusted directories.
+.PD
+.SH SEE ALSO
+.BR ldd (1),
+.BR ld.so (8)
diff --git a/man/man8/nscd.8 b/man/man8/nscd.8
new file mode 100644
index 000000000..a172fdef8
--- /dev/null
+++ b/man/man8/nscd.8
@@ -0,0 +1,84 @@
+.\" Copyright 1999 SuSE GmbH Nuernberg, Germany
+.\" Author: Thorsten Kukuk <kukuk@suse.de>
+.\"
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\"
+.\" 2008-12-05 Petr Baudis <pasky@suse.cz>
+.\"	Rewrite the NOTES section to reflect modern reality
+.\"
+.TH nscd 8 (date) "Linux man-pages (unreleased)"
+.SH NAME
+nscd \- name service cache daemon
+.SH DESCRIPTION
+.B nscd
+is a daemon that provides a cache for the most common name service
+requests.
+The default configuration file,
+.IR /etc/nscd.conf ,
+determines the behavior of the cache daemon.
+See
+.BR nscd.conf (5).
+.P
+.B nscd
+provides caching for accesses of the
+.BR passwd (5),
+.BR group (5),
+.BR hosts (5)
+.BR services (5)
+and
+.I netgroup
+databases through standard libc interfaces, such as
+.BR getpwnam (3),
+.BR getpwuid (3),
+.BR getgrnam (3),
+.BR getgrgid (3),
+.BR gethostbyname (3),
+and others.
+.P
+There are two caches for each database:
+a positive one for items found, and a negative one
+for items not found.
+Each cache has a separate TTL (time-to-live)
+period for its data.
+Note that the shadow file is specifically not cached.
+.BR getspnam (3)
+calls remain uncached as a result.
+.SH OPTIONS
+.TP
+.B "\-\-help"
+will give you a list with all options and what they do.
+.SH NOTES
+The daemon will try to watch for changes in configuration files
+appropriate for each database (e.g.,
+.I /etc/passwd
+for the
+.I passwd
+database or
+.I /etc/hosts
+and
+.I /etc/resolv.conf
+for the
+.I hosts
+database), and flush the cache when these are changed.
+However, this will happen only after a short delay (unless the
+.BR inotify (7)
+mechanism is available and glibc 2.9 or later is available),
+and this auto-detection does not cover configuration files
+required by nonstandard NSS modules, if any are specified in
+.IR /etc/nsswitch.conf .
+In that case, you need to run the following command
+after changing the configuration file of the database so that
+.B nscd
+invalidates its cache:
+.P
+.in +4n
+.EX
+$ \fBnscd \-i\fP \fI<database>\fP
+.EE
+.in
+.SH SEE ALSO
+.BR nscd.conf (5),
+.BR nsswitch.conf (5)
+.\" .SH AUTHOR
+.\" .B nscd
+.\" was written by Thorsten Kukuk and Ulrich Drepper.
diff --git a/man/man8/sln.8 b/man/man8/sln.8
new file mode 100644
index 000000000..b8880a830
--- /dev/null
+++ b/man/man8/sln.8
@@ -0,0 +1,44 @@
+.\" Copyright (c) 2013 by Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sln 8 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sln \- create symbolic links
+.SH SYNOPSIS
+.nf
+.BI sln " source dest"
+.BI sln " filelist"
+.fi
+.SH DESCRIPTION
+The
+.B sln
+program creates symbolic links.
+Unlike the
+.BR ln (1)
+program, it is statically linked.
+This means that if for some reason the dynamic linker is not working,
+.B sln
+can be used to make symbolic links to dynamic libraries.
+.P
+The command line has two forms.
+In the first form, it creates
+.I dest
+as a new symbolic link to
+.IR source .
+.P
+In the second form,
+.I filelist
+is a list of space-separated pathname pairs,
+and the effect is as if
+.B sln
+was executed once for each line of the file,
+with the two pathnames as the arguments.
+.P
+The
+.B sln
+program supports no command-line options.
+.SH SEE ALSO
+.BR ln (1),
+.BR ld.so (8),
+.BR ldconfig (8)
diff --git a/man/man8/tzselect.8 b/man/man8/tzselect.8
new file mode 100644
index 000000000..ee031614f
--- /dev/null
+++ b/man/man8/tzselect.8
@@ -0,0 +1,125 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.TH tzselect 8 "" "Time Zone Database"
+.SH NAME
+tzselect \- select a timezone
+.SH SYNOPSIS
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+.ds d " degrees
+.ds m " minutes
+.ds s " seconds
+.ds _ " \&
+.if t \{\
+. if \n(.g .if c \(de .if c \(fm .if c \(sd \{\
+.  ds d \(de
+.  ds m \(fm
+.  ds s \(sd
+.  ds _ \|
+. \}
+.\}
+.B tzselect
+[
+.B \*-c
+.I coord
+] [
+.B \*-n
+.I limit
+] [
+.B \*-\*-help
+] [
+.B \*-\*-version
+]
+.SH DESCRIPTION
+The
+.B tzselect
+program asks the user for information about the current location,
+and outputs the resulting timezone to standard output.
+The output is suitable as a value for the TZ environment variable.
+.PP
+All interaction with the user is done via standard input and standard error.
+.SH OPTIONS
+.TP
+.BI "\*-c " coord
+Instead of asking for continent and then country and then city,
+ask for selection from time zones whose largest cities
+are closest to the location with geographical coordinates
+.I coord.
+Use ISO 6709 notation for
+.I coord,
+that is, a latitude immediately followed by a longitude.  The latitude
+and longitude should be signed integers followed by an optional
+decimal point and fraction: positive numbers represent north and east,
+negative south and west.  Latitudes with two and longitudes with three
+integer digits are treated as degrees; latitudes with four or six and
+longitudes with five or seven integer digits are treated as
+.I "DDMM, DDDMM, DDMMSS,"
+or
+.I DDDMMSS
+representing
+.I DD
+or
+.I DDD
+degrees,
+.I MM
+minutes,
+and zero or
+.I SS
+seconds, with any trailing fractions represent fractional minutes or
+(if
+.I SS
+is present) seconds.  The decimal point is that of the current locale.
+For example, in the (default) C locale,
+.B "\*-c\ +40.689\*-074.045"
+specifies 40.689\*d\*_N, 74.045\*d\*_W,
+.B "\*-c\ +4041.4\*-07402.7"
+specifies 40\*d\*_41.4\*m\*_N, 74\*d\*_2.7\*m\*_W, and
+.B "\*-c\ +404121\*-0740240"
+specifies 40\*d\*_41\*m\*_21\*s\*_N, 74\*d\*_2\*m\*_40\*s\*_W.
+If
+.I coord
+is not one of the documented forms, the resulting behavior is unspecified.
+.TP
+.BI "\*-n " limit
+When
+.B \*-c
+is used, display the closest
+.I limit
+locations (default 10).
+.TP
+.B "\*-\*-help"
+Output help information and exit.
+.TP
+.B "\*-\*-version"
+Output version information and exit.
+.SH "ENVIRONMENT VARIABLES"
+.TP
+\f3AWK\fP
+Name of a POSIX-compliant
+.B awk
+program (default:
+.BR awk ).
+.TP
+\f3TZDIR\fP
+Name of the directory containing timezone data files (default:
+.BR /usr/share/zoneinfo ).
+.SH FILES
+.TP
+\f2TZDIR\fP\f3/iso3166.tab\fP
+Table of ISO 3166 2-letter country codes and country names.
+.TP
+\f2TZDIR\fP\f3/zone1970.tab\fP
+Table of country codes, latitude and longitude, timezones, and
+descriptive comments.
+.TP
+\f2TZDIR\fP\f3/\fP\f2TZ\fP
+Timezone data file for timezone \f2TZ\fP.
+.SH "EXIT STATUS"
+The exit status is zero if a timezone was successfully obtained from the user,
+nonzero otherwise.
+.SH "SEE ALSO"
+newctime(3), tzfile(5), zdump(8), zic(8)
+.SH NOTES
+Applications should not assume that
+.BR tzselect 's
+output matches the user's political preferences.
diff --git a/man/man8/zdump.8 b/man/man8/zdump.8
new file mode 100644
index 000000000..c3f0bba60
--- /dev/null
+++ b/man/man8/zdump.8
@@ -0,0 +1,230 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.TH zdump 8 "" "Time Zone Database"
+.SH NAME
+zdump \- timezone dumper
+.SH SYNOPSIS
+.B zdump
+[
+.I option
+\&... ] [
+.I timezone
+\&... ]
+.SH DESCRIPTION
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
+.ie \n(.g .ds - \f(CR-\fP
+.el .ds - \-
+The
+.B zdump
+program prints the current time in each
+.I timezone
+named on the command line.
+.SH OPTIONS
+.TP
+.B \*-\*-version
+Output version information and exit.
+.TP
+.B \*-\*-help
+Output short usage message and exit.
+.TP
+.B \*-i
+Output a description of time intervals.  For each
+.I timezone
+on the command line, output an interval-format description of the
+timezone.  See
+.q "INTERVAL FORMAT"
+below.
+.TP
+.B \*-v
+Output a verbose description of time intervals.
+For each
+.I timezone
+on the command line,
+print the times at the two extreme time values,
+the times (if present) at and just beyond the boundaries of years that
+.BR localtime (3)
+and
+.BR gmtime (3)
+can represent, and
+the times both one second before and exactly at
+each detected time discontinuity.
+Each line is followed by
+.BI isdst= D
+where
+.I D
+is positive, zero, or negative depending on whether
+the given time is daylight saving time, standard time,
+or an unknown time type, respectively.
+Each line is also followed by
+.BI gmtoff= N
+if the given local time is known to be
+.I N
+seconds east of Greenwich.
+.TP
+.B \*-V
+Like
+.BR \*-v ,
+except omit output concerning extreme time and year values.
+This generates output that is easier to compare to that of
+implementations with different time representations.
+.TP
+.BI "\*-c " \fR[\fIloyear , \fR]\fIhiyear
+Cut off interval output at the given year(s).
+Cutoff times are computed using the proleptic Gregorian calendar with year 0
+and with Universal Time (UT) ignoring leap seconds.
+Cutoffs are at the start of each year, where the lower-bound
+timestamp is inclusive and the upper is exclusive; for example,
+.B "\*-c 1970,2070"
+selects transitions on or after 1970-01-01 00:00:00 UTC
+and before 2070-01-01 00:00:00 UTC.
+The default cutoff is
+.BR \*-500,2500 .
+.TP
+.BI "\*-t " \fR[\fIlotime , \fR]\fIhitime
+Cut off interval output at the given time(s),
+given in decimal seconds since 1970-01-01 00:00:00
+Coordinated Universal Time (UTC).
+The
+.I timezone
+determines whether the count includes leap seconds.
+As with
+.BR \*-c ,
+the cutoff's lower bound is inclusive and its upper bound is exclusive.
+.SH "INTERVAL FORMAT"
+The interval format is a compact text representation that is intended
+to be both human- and machine-readable.  It consists of an empty line,
+then a line
+.q "TZ=\fIstring\fP"
+where
+.I string
+is a double-quoted string giving the timezone, a second line
+.q "\*- \*- \fIinterval\fP"
+describing the time interval before the first transition if any, and
+zero or more following lines
+.q "\fIdate time interval\fP",
+one line for each transition time and following interval.  Fields are
+separated by single tabs.
+.PP
+Dates are in
+.IR yyyy - mm - dd
+format and times are in 24-hour
+.IR hh : mm : ss
+format where
+.IR hh <24.
+Times are in local time immediately after the transition.  A
+time interval description consists of a UT offset in signed
+.RI \(+- hhmmss
+format, a time zone abbreviation, and an isdst flag.  An abbreviation
+that equals the UT offset is omitted; other abbreviations are
+double-quoted strings unless they consist of one or more alphabetic
+characters.  An isdst flag is omitted for standard time, and otherwise
+is a decimal integer that is unsigned and positive (typically 1) for
+daylight saving time and negative for unknown.
+.PP
+In times and in UT offsets with absolute value less than 100 hours,
+the seconds are omitted if they are zero, and
+the minutes are also omitted if they are also zero.  Positive UT
+offsets are east of Greenwich.  The UT offset \*-00 denotes a UT
+placeholder in areas where the actual offset is unspecified; by
+convention, this occurs when the UT offset is zero and the time zone
+abbreviation begins with
+.q "\*-"
+or is
+.q "zzz".
+.PP
+In double-quoted strings, escape sequences represent unusual
+characters.  The escape sequences are \es for space, and \e", \e\e,
+\ef, \en, \er, \et, and \ev with their usual meaning in the C
+programming language.  E.g., the double-quoted string
+\*(lq"CET\es\e"\e\e"\*(rq represents the character sequence \*(lqCET
+"\e\*(rq.\""
+.PP
+.ne 9
+Here is an example of the output, with the leading empty line omitted.
+(This example is shown with tab stops set far enough apart so that the
+tabbed columns line up.)
+.nf
+.sp
+.if \n(.g .ft CR
+.in +2
+.nr w \w'1896-01-13  'u+\n(.i
+.ta \w'1896-01-13\0\0'u +\w'12:01:26\0\0'u +\w'-103126\0\0'u +\w'HWT\0\0'u
+TZ="Pacific/Honolulu"
+-	-	-103126	LMT
+1896-01-13	12:01:26	-1030	HST
+1933-04-30	03	-0930	HDT	1
+1933-05-21	11	-1030	HST
+1942-02-09	03	-0930	HWT	1
+1945-08-14	13:30	-0930	HPT	1
+1945-09-30	01	-1030	HST
+1947-06-08	02:30	-10	HST
+.in
+.if \n(.g .ft
+.sp
+.fi
+Here, local time begins 10 hours, 31 minutes and 26 seconds west of
+UT, and is a standard time abbreviated LMT.  Immediately after the
+first transition, the date is 1896-01-13 and the time is 12:01:26, and
+the following time interval is 10.5 hours west of UT, a standard time
+abbreviated HST.  Immediately after the second transition, the date is
+1933-04-30 and the time is 03:00:00 and the following time interval is
+9.5 hours west of UT, is abbreviated HDT, and is daylight saving time.
+Immediately after the last transition the date is 1947-06-08 and the
+time is 02:30:00, and the following time interval is 10 hours west of
+UT, a standard time abbreviated HST.
+.PP
+.ne 10
+Here are excerpts from another example:
+.nf
+.sp
+.if \n(.g .ft CR
+.if t .in +.5i
+.if n .in +2
+TZ="Europe/Astrakhan"
+-	-	+031212	LMT
+1924-04-30	23:47:48	+03
+1930-06-21	01	+04
+1981-04-01	01	+05		1
+1981-09-30	23	+04
+\&...
+2014-10-26	01	+03
+2016-03-27	03	+04
+.in
+.if \n(.g .ft
+.sp
+.fi
+This time zone is east of UT, so its UT offsets are positive.  Also,
+many of its time zone abbreviations are omitted since they duplicate
+the text of the UT offset.
+.SH LIMITATIONS
+Time discontinuities are found by sampling the results returned by
+.BR localtime (3)
+at twelve-hour intervals.
+This works in all real-world cases;
+one can construct artificial time zones for which this fails.
+.PP
+In the
+.B \*-v
+and
+.B \*-V
+output,
+.q "UT"
+denotes the value returned by
+.BR gmtime (3),
+which uses UTC for modern timestamps and some other UT flavor for
+timestamps that predate the introduction of UTC.
+No attempt is currently made to have the output use
+.q "UTC"
+for newer and
+.q "UT"
+for older timestamps, partly because the exact date of the
+introduction of UTC is problematic.
+.SH SEE ALSO
+.BR tzfile (5),
+.BR zic (8)
diff --git a/man/man8/zic.8 b/man/man8/zic.8
new file mode 100644
index 000000000..0ad373a2d
--- /dev/null
+++ b/man/man8/zic.8
@@ -0,0 +1,894 @@
+.\" This file is in the public domain, so clarified as of
+.\" 2009-05-17 by Arthur David Olson.
+.TH zic 8 "" "Time Zone Database"
+.SH NAME
+zic \- timezone compiler
+.SH SYNOPSIS
+.B zic
+[
+.I option
+\&... ] [
+.I filename
+\&... ]
+.SH DESCRIPTION
+.ie '\(lq'' .ds lq \&"\"
+.el .ds lq \(lq\"
+.ie '\(rq'' .ds rq \&"\"
+.el .ds rq \(rq\"
+.de q
+\\$3\*(lq\\$1\*(rq\\$2
+..
+.ie '\(la'' .ds < <
+.el .ds < \(la
+.ie '\(ra'' .ds > >
+.el .ds > \(ra
+.ie \n(.g \{\
+.  ds : \:
+.  ds - \f(CR-\fP
+.\}
+.el \{\
+.  ds :
+.  ds - \-
+.\}
+.ds d " degrees
+.ds m " minutes
+.ds s " seconds
+.ds _ " \&
+.if t \{\
+. if \n(.g .if c \(de .if c \(fm .if c \(sd \{\
+.  ds d \(de
+.  ds m \(fm
+.  ds s \(sd
+.  ds _ \|
+. \}
+.\}
+The
+.B zic
+program reads text from the file(s) named on the command line
+and creates the timezone information format (TZif) files
+specified in this input.
+If a
+.I filename
+is
+.q "\*-" ,
+standard input is read.
+.SH OPTIONS
+.TP
+.B "\*-\*-version"
+Output version information and exit.
+.TP
+.B \*-\*-help
+Output short usage message and exit.
+.TP
+.BI "\*-b " bloat
+Output backward-compatibility data as specified by
+.IR bloat .
+If
+.I bloat
+is
+.BR fat ,
+generate additional data entries that work around potential bugs or
+incompatibilities in older software, such as software that mishandles
+the 64-bit generated data.
+If
+.I bloat
+is
+.BR slim ,
+keep the output files small; this can help check for the bugs
+and incompatibilities.
+The default is
+.BR slim ,
+as software that mishandles 64-bit data typically
+mishandles timestamps after the year 2038 anyway.
+Also see the
+.B \*-r
+option for another way to alter output size.
+.TP
+.BI "\*-d " directory
+Create time conversion information files in the named directory rather than
+in the standard directory named below.
+.TP
+.BI "\*-l " timezone
+Use
+.I timezone
+as local time.
+.B zic
+will act as if the input contained a link line of the form
+.sp
+.ti +2
+.ta \w'Link\0\0'u  +\w'\fItimezone\fP\0\0'u
+Link	\fItimezone\fP		localtime
+.sp
+If
+.I timezone
+is
+.BR \*- ,
+any already-existing link is removed.
+.TP
+.BI "\*-L " leapsecondfilename
+Read leap second information from the file with the given name.
+If this option is not used,
+no leap second information appears in output files.
+.TP
+.BI "\*-p " timezone
+Use
+.IR timezone 's
+rules when handling nonstandard
+TZ strings like "EET\*-2EEST" that lack transition rules.
+.B zic
+will act as if the input contained a link line of the form
+.sp
+.ti +2
+Link	\fItimezone\fP		posixrules
+.sp
+If
+.I timezone
+is
+.q "\*-"
+(the default), any already-existing link is removed.
+.sp
+Unless
+.I timezone is
+.q "\*-" ,
+this option is obsolete and poorly supported.
+Among other things it should not be used for timestamps after the year 2037,
+and it should not be combined with
+.B "\*-b slim"
+if
+.IR timezone 's
+transitions are at standard time or Universal Time (UT) instead of local time.
+.TP
+.BR "\*-r " "[\fB@\fP\fIlo\fP][\fB/@\fP\fIhi\fP]"
+Limit the applicability of output files
+to timestamps in the range from
+.I lo
+(inclusive) to
+.I hi
+(exclusive), where
+.I lo
+and
+.I hi
+are possibly signed decimal counts of seconds since the Epoch
+(1970-01-01 00:00:00 UTC).
+Omitted counts default to extreme values.
+The output files use UT offset 0 and abbreviation
+.q "\*-00"
+in place of the omitted timestamp data.
+For example,
+.q "zic \*-r @0"
+omits data intended for negative timestamps (i.e., before the Epoch), and
+.q "zic \*-r @0/@2147483648"
+outputs data intended only for nonnegative timestamps that fit into
+31-bit signed integers.
+On platforms with GNU
+.BR date ,
+.q "zic \*-r @$(date +%s)"
+omits data intended for past timestamps.
+Although this option typically reduces the output file's size,
+the size can increase due to the need to represent the timestamp range
+boundaries, particularly if
+.I hi
+causes a TZif file to contain explicit entries for
+.RI pre- hi
+transitions rather than concisely representing them
+with an extended POSIX.1-2017 TZ string.
+Also see the
+.B "\*-b slim"
+option for another way to shrink output size.
+.TP
+.BI "\*-R @" hi
+Generate redundant trailing explicit transitions for timestamps
+that occur less than
+.I hi
+seconds since the Epoch, even though the transitions could be
+more concisely represented via the extended POSIX.1-2017 TZ string.
+This option does not affect the represented timestamps.
+Although it accommodates nonstandard TZif readers
+that ignore the extended POSIX.1-2017 TZ string,
+it increases the size of the altered output files.
+.TP
+.BI "\*-t " file
+When creating local time information, put the configuration link in
+the named file rather than in the standard location.
+.TP
+.B \*-v
+Be more verbose, and complain about the following situations:
+.RS
+.PP
+The input specifies a link to a link,
+something not supported by some older parsers, including
+.B zic
+itself through release 2022e.
+.PP
+A year that appears in a data file is outside the range
+of representable years.
+.PP
+A time of 24:00 or more appears in the input.
+Pre-1998 versions of
+.B zic
+prohibit 24:00, and pre-2007 versions prohibit times greater than 24:00.
+.PP
+A rule goes past the start or end of the month.
+Pre-2004 versions of
+.B zic
+prohibit this.
+.PP
+A time zone abbreviation uses a
+.B %z
+format.
+Pre-2015 versions of
+.B zic
+do not support this.
+.PP
+A timestamp contains fractional seconds.
+Pre-2018 versions of
+.B zic
+do not support this.
+.PP
+The input contains abbreviations that are mishandled by pre-2018 versions of
+.B zic
+due to a longstanding coding bug.
+These abbreviations include
+.q L
+for
+.q Link ,
+.q mi
+for
+.q min ,
+.q Sa
+for
+.q Sat ,
+and
+.q Su
+for
+.q Sun .
+.PP
+The output file does not contain all the information about the
+long-term future of a timezone, because the future cannot be summarized as
+an extended POSIX.1-2017 TZ string.  For example, as of 2023 this problem
+occurs for Morocco's daylight-saving rules, as these rules are based
+on predictions for when Ramadan will be observed, something that
+an extended POSIX.1-2017 TZ string cannot represent.
+.PP
+The output contains data that may not be handled properly by client
+code designed for older
+.B zic
+output formats.  These compatibility issues affect only timestamps
+before 1970 or after the start of 2038.
+.PP
+The output contains a truncated leap second table,
+which can cause some older TZif readers to misbehave.
+This can occur if the
+.B "\*-L"
+option is used, and either an Expires line is present or
+the
+.B "\*-r"
+option is also used.
+.PP
+The output file contains more than 1200 transitions,
+which may be mishandled by some clients.
+The current reference client supports at most 2000 transitions;
+pre-2014 versions of the reference client support at most 1200
+transitions.
+.PP
+A time zone abbreviation has fewer than 3 or more than 6 characters.
+POSIX requires at least 3, and requires implementations to support
+at least 6.
+.PP
+An output file name contains a byte that is not an ASCII letter,
+.q "\*-" ,
+.q "/" ,
+or
+.q "_" ;
+or it contains a file name component that contains more than 14 bytes
+or that starts with
+.q "\*-" .
+.RE
+.SH FILES
+Input files use the format described in this section; output files use
+.BR tzfile (5)
+format.
+.PP
+Input files should be text files, that is, they should be a series of
+zero or more lines, each ending in a newline byte and containing at
+most 2048 bytes counting the newline, and without any NUL bytes.
+The input text's encoding
+is typically UTF-8 or ASCII; it should have a unibyte representation
+for the POSIX Portable Character Set (PPCS)
+\*<https://pubs\*:.opengroup\*:.org/\*:onlinepubs/\*:9699919799/\*:basedefs/\*:V1_chap06\*:.html\*>
+and the encoding's non-unibyte characters should consist entirely of
+non-PPCS bytes.  Non-PPCS characters typically occur only in comments:
+although output file names and time zone abbreviations can contain
+nearly any character, other software will work better if these are
+limited to the restricted syntax described under the
+.B \*-v
+option.
+.PP
+Input lines are made up of fields.
+Fields are separated from one another by one or more white space characters.
+The white space characters are space, form feed, carriage return, newline,
+tab, and vertical tab.
+Leading and trailing white space on input lines is ignored.
+An unquoted sharp character (#) in the input introduces a comment which extends
+to the end of the line the sharp character appears on.
+White space characters and sharp characters may be enclosed in double quotes
+(") if they're to be used as part of a field.
+Any line that is blank (after comment stripping) is ignored.
+Nonblank lines are expected to be of one of three types:
+rule lines, zone lines, and link lines.
+.PP
+Names must be in English and are case insensitive.
+They appear in several contexts, and include month and weekday names
+and keywords such as
+.BR "maximum" ,
+.BR "only" ,
+.BR "Rolling" ,
+and
+.BR "Zone" .
+A name can be abbreviated by omitting all but an initial prefix; any
+abbreviation must be unambiguous in context.
+.PP
+A rule line has the form
+.nf
+.ti +2
+.ta \w'Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'1973\0\0'u +\w'\*-\0\0'u +\w'Apr\0\0'u +\w'lastSun\0\0'u +\w'2:00w\0\0'u +\w'1:00d\0\0'u
+.sp
+Rule	NAME	FROM	TO	\*-	IN	ON	AT	SAVE	LETTER/S
+.sp
+For example:
+.ti +2
+.sp
+Rule	US	1967	1973	\*-	Apr	lastSun	2:00w	1:00d	D
+.sp
+.fi
+The fields that make up a rule line are:
+.TP
+.B NAME
+Gives the name of the rule set that contains this line.
+The name must start with a character that is neither
+an ASCII digit nor
+.q \*-
+nor
+.q + .
+To allow for future extensions,
+an unquoted name should not contain characters from the set
+.ie \n(.g .q \f(CR!$%&\(aq()*,/:;<=>?@[\e]\(ha\(ga{|}\(ti\fP .
+.el .ie t .q \f(CW!$%&'()*,/:;<=>?@[\e]^\(ga{|}~\fP .
+.el .q !$%&'()*,/:;<=>?@[\e]^`{|}~ .
+.TP
+.B FROM
+Gives the first year in which the rule applies.
+Any signed integer year can be supplied; the proleptic Gregorian calendar
+is assumed, with year 0 preceding year 1.
+Rules can describe times that are not representable as time values,
+with the unrepresentable times ignored; this allows rules to be portable
+among hosts with differing time value types.
+.TP
+.B TO
+Gives the final year in which the rule applies.
+The word
+.B maximum
+(or an abbreviation) means the indefinite future, and the word
+.B only
+(or an abbreviation)
+may be used to repeat the value of the
+.B FROM
+field.
+.TP
+.B \*-
+Is a reserved field and should always contain
+.q \*-
+for compatibility with older versions of
+.BR zic .
+It was previously known as the
+.B TYPE
+field, which could contain values to allow a
+separate script to further restrict in which
+.q types
+of years the rule would apply.
+.TP
+.B IN
+Names the month in which the rule takes effect.
+Month names may be abbreviated.
+.TP
+.B ON
+Gives the day on which the rule takes effect.
+Recognized forms include:
+.nf
+.in +2
+.sp
+.ta \w'Sun<=25\0\0'u
+5	the fifth of the month
+lastSun	the last Sunday in the month
+lastMon	the last Monday in the month
+Sun>=8	first Sunday on or after the eighth
+Sun<=25	last Sunday on or before the 25th
+.fi
+.in
+.sp
+A weekday name (e.g.,
+.BR "Sunday" )
+or a weekday name preceded by
+.q "last"
+(e.g.,
+.BR "lastSunday" )
+may be abbreviated or spelled out in full.
+There must be no white space characters within the
+.B ON
+field.
+The
+.q <=
+and
+.q >=
+constructs can result in a day in the neighboring month;
+for example, the IN-ON combination
+.q "Oct Sun>=31"
+stands for the first Sunday on or after October 31,
+even if that Sunday occurs in November.
+.TP
+.B AT
+Gives the time of day at which the rule takes effect,
+relative to 00:00, the start of a calendar day.
+Recognized forms include:
+.nf
+.in +2
+.sp
+.ta \w'00:19:32.13\0\0'u
+2	time in hours
+2:00	time in hours and minutes
+01:28:14	time in hours, minutes, and seconds
+00:19:32.13	time with fractional seconds
+12:00	midday, 12 hours after 00:00
+15:00	3 PM, 15 hours after 00:00
+24:00	end of day, 24 hours after 00:00
+260:00	260 hours after 00:00
+\*-2:30	2.5 hours before 00:00
+\*-	equivalent to 0
+.fi
+.in
+.sp
+Although
+.B zic
+rounds times to the nearest integer second
+(breaking ties to the even integer), the fractions may be useful
+to other applications requiring greater precision.
+The source format does not specify any maximum precision.
+Any of these forms may be followed by the letter
+.B w
+if the given time is local or
+.q "wall clock"
+time,
+.B s
+if the given time is standard time without any adjustment for daylight saving,
+or
+.B u
+(or
+.B g
+or
+.BR z )
+if the given time is universal time;
+in the absence of an indicator,
+local (wall clock) time is assumed.
+These forms ignore leap seconds; for example,
+if a leap second occurs at 00:59:60 local time,
+.q "1:00"
+stands for 3601 seconds after local midnight instead of the usual 3600 seconds.
+The intent is that a rule line describes the instants when a
+clock/calendar set to the type of time specified in the
+.B AT
+field would show the specified date and time of day.
+.TP
+.B SAVE
+Gives the amount of time to be added to local standard time when the rule is in
+effect, and whether the resulting time is standard or daylight saving.
+This field has the same format as the
+.B AT
+field
+except with a different set of suffix letters:
+.B s
+for standard time and
+.B d
+for daylight saving time.
+The suffix letter is typically omitted, and defaults to
+.B s
+if the offset is zero and to
+.B d
+otherwise.
+Negative offsets are allowed; in Ireland, for example, daylight saving
+time is observed in winter and has a negative offset relative to
+Irish Standard Time.
+The offset is merely added to standard time; for example,
+.B zic
+does not distinguish a 10:30 standard time plus an 0:30
+.B SAVE
+from a 10:00 standard time plus a 1:00
+.BR SAVE .
+.TP
+.B LETTER/S
+Gives the
+.q "variable part"
+(for example, the
+.q "S"
+or
+.q "D"
+in
+.q "EST"
+or
+.q "EDT" )
+of time zone abbreviations to be used when this rule is in effect.
+If this field is
+.q \*- ,
+the variable part is null.
+.PP
+A zone line has the form
+.sp
+.nf
+.ti +2
+.ta \w'Zone\0\0'u +\w'Asia/Amman\0\0'u +\w'STDOFF\0\0'u +\w'Jordan\0\0'u +\w'FORMAT\0\0'u
+Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
+.sp
+For example:
+.sp
+.ti +2
+Zone	Asia/Amman	2:00	Jordan	EE%sT	2017 Oct 27 01:00
+.sp
+.fi
+The fields that make up a zone line are:
+.TP
+.B NAME
+The name of the timezone.
+This is the name used in creating the time conversion information file for the
+timezone.
+It should not contain a file name component
+.q ".\&"
+or
+.q ".." ;
+a file name component is a maximal substring that does not contain
+.q "/" .
+.TP
+.B STDOFF
+The amount of time to add to UT to get standard time,
+without any adjustment for daylight saving.
+This field has the same format as the
+.B AT
+and
+.B SAVE
+fields of rule lines, except without suffix letters;
+begin the field with a minus sign if time must be subtracted from UT.
+.TP
+.B RULES
+The name of the rules that apply in the timezone or,
+alternatively, a field in the same format as a rule-line SAVE column,
+giving the amount of time to be added to local standard time
+and whether the resulting time is standard or daylight saving.
+If this field is
+.B \*-
+then standard time always applies.
+When an amount of time is given, only the sum of standard time and
+this amount matters.
+.TP
+.B FORMAT
+The format for time zone abbreviations.
+The pair of characters
+.B %s
+is used to show where the
+.q "variable part"
+of the time zone abbreviation goes.
+Alternatively, a format can use the pair of characters
+.B %z
+to stand for the UT offset in the form
+.RI \(+- hh ,
+.RI \(+- hhmm ,
+or
+.RI \(+- hhmmss ,
+using the shortest form that does not lose information, where
+.IR hh ,
+.IR mm ,
+and
+.I ss
+are the hours, minutes, and seconds east (+) or west (\-) of UT.
+Alternatively,
+a slash (/)
+separates standard and daylight abbreviations.
+To conform to POSIX, a time zone abbreviation should contain only
+alphanumeric ASCII characters,
+.q "+"
+and
+.q "\*-".
+By convention, the time zone abbreviation
+.q "\*-00"
+is a placeholder that means local time is unspecified.
+.TP
+.B UNTIL
+The time at which the UT offset or the rule(s) change for a location.
+It takes the form of one to four fields YEAR [MONTH [DAY [TIME]]].
+If this is specified,
+the time zone information is generated from the given UT offset
+and rule change until the time specified, which is interpreted using
+the rules in effect just before the transition.
+The month, day, and time of day have the same format as the IN, ON, and AT
+fields of a rule; trailing fields can be omitted, and default to the
+earliest possible value for the missing fields.
+.IP
+The next line must be a
+.q "continuation"
+line; this has the same form as a zone line except that the
+string
+.q "Zone"
+and the name are omitted, as the continuation line will
+place information starting at the time specified as the
+.q "until"
+information in the previous line in the file used by the previous line.
+Continuation lines may contain
+.q "until"
+information, just as zone lines do, indicating that the next line is a further
+continuation.
+.PP
+If a zone changes at the same instant that a rule would otherwise take
+effect in the earlier zone or continuation line, the rule is ignored.
+A zone or continuation line
+.I L
+with a named rule set starts with standard time by default:
+that is, any of
+.IR L 's
+timestamps preceding
+.IR L 's
+earliest rule use the rule in effect after
+.IR L 's
+first transition into standard time.
+In a single zone it is an error if two rules take effect at the same
+instant, or if two zone changes take effect at the same instant.
+.PP
+If a continuation line subtracts
+.I N
+seconds from the UT offset after a transition that would be
+interpreted to be later if using the continuation line's UT offset and
+rules, the
+.q "until"
+time of the previous zone or continuation line is interpreted
+according to the continuation line's UT offset and rules, and any rule
+that would otherwise take effect in the next
+.I N
+seconds is instead assumed to take effect simultaneously.
+For example:
+.br
+.ne 7
+.nf
+.in +2
+.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'2006\0\0'u +\w'\*-\0\0'u +\w'Oct\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u
+.sp
+# Rule	NAME	FROM	TO	\*-	IN	ON	AT	SAVE	LETTER/S
+Rule	US	1967	2006	-	Oct	lastSun	2:00	0	S
+Rule	US	1967	1973	-	Apr	lastSun	2:00	1:00	D
+.ta \w'# Zone\0\0'u +\w'America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
+# Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
+Zone	America/Menominee	\*-5:00	\*-	EST	1973 Apr 29 2:00
+	\*-6:00	US	C%sT
+.sp
+.in
+.fi
+Here, an incorrect reading would be there were two clock changes on 1973-04-29,
+the first from 02:00 EST (\*-05) to 01:00 CST (\*-06),
+and the second an hour later from 02:00 CST (\*-06) to 03:00 CDT (\*-05).
+However,
+.B zic
+interprets this more sensibly as a single transition from 02:00 CST (\*-05) to
+02:00 CDT (\*-05).
+.PP
+A link line has the form
+.sp
+.nf
+.ti +2
+.ta \w'Link\0\0'u +\w'Europe/Istanbul\0\0'u
+Link	TARGET	LINK-NAME
+.sp
+For example:
+.sp
+.ti +2
+Link	Europe/Istanbul	Asia/Istanbul
+.sp
+.fi
+The
+.B TARGET
+field should appear as the
+.B NAME
+field in some zone line or as the
+.B LINK-NAME
+field in some link line.
+The
+.B LINK-NAME
+field is used as an alternative name for that zone;
+it has the same syntax as a zone line's
+.B NAME
+field.
+Links can chain together, although the behavior is unspecified if a
+chain of one or more links does not terminate in a Zone name.
+A link line can appear before the line that defines the link target.
+For example:
+.sp
+.ne 3
+.nf
+.in +2
+.ta \w'Zone\0\0'u +\w'Greenwich\0\0'u
+Link	Greenwich	G_M_T
+Link	Etc/GMT	Greenwich
+Zone	Etc/GMT\0\00\0\0\*-\0\0GMT
+.sp
+.in
+.fi
+The two links are chained together, and G_M_T, Greenwich, and Etc/GMT
+all name the same zone.
+.PP
+Except for continuation lines,
+lines may appear in any order in the input.
+However, the behavior is unspecified if multiple zone or link lines
+define the same name.
+.PP
+The file that describes leap seconds can have leap lines and an
+expiration line.
+Leap lines have the following form:
+.nf
+.ti +2
+.ta \w'Leap\0\0'u +\w'YEAR\0\0'u +\w'MONTH\0\0'u +\w'DAY\0\0'u +\w'HH:MM:SS\0\0'u +\w'CORR\0\0'u
+.sp
+Leap	YEAR	MONTH	DAY	HH:MM:SS	CORR	R/S
+.sp
+For example:
+.ti +2
+.sp
+Leap	2016	Dec	31	23:59:60	+	S
+.sp
+.fi
+The
+.BR YEAR ,
+.BR MONTH ,
+.BR DAY ,
+and
+.B HH:MM:SS
+fields tell when the leap second happened.
+The
+.B CORR
+field
+should be
+.q "+"
+if a second was added
+or
+.q "\*-"
+if a second was skipped.
+The
+.B R/S
+field
+should be (an abbreviation of)
+.q "Stationary"
+if the leap second time given by the other fields should be interpreted as UTC
+or
+(an abbreviation of)
+.q "Rolling"
+if the leap second time given by the other fields should be interpreted as
+local (wall clock) time.
+.PP
+Rolling leap seconds were implemented back when it was not
+clear whether common practice was rolling or stationary,
+with concerns that one would see
+Times Square ball drops where there'd be a
+.q "3... 2... 1... leap... Happy New Year"
+countdown, placing the leap second at
+midnight New York time rather than midnight UTC.
+However, this countdown style does not seem to have caught on,
+which means rolling leap seconds are not used in practice;
+also, they are not supported if the
+.B \*-r
+option is used.
+.PP
+The expiration line, if present, has the form:
+.nf
+.ti +2
+.ta \w'Expires\0\0'u +\w'YEAR\0\0'u +\w'MONTH\0\0'u +\w'DAY\0\0'u
+.sp
+Expires	YEAR	MONTH	DAY	HH:MM:SS
+.sp
+For example:
+.ti +2
+.sp
+Expires	2020	Dec	28	00:00:00
+.sp
+.fi
+The
+.BR YEAR ,
+.BR MONTH ,
+.BR DAY ,
+and
+.B HH:MM:SS
+fields give the expiration timestamp in UTC for the leap second table.
+.br
+.ne 22
+.SH "EXTENDED EXAMPLE"
+Here is an extended example of
+.B zic
+input, intended to illustrate many of its features.
+.nf
+.in +2
+.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'1973\0\0'u +\w'\*-\0\0'u +\w'Apr\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u
+.sp
+# Rule	NAME	FROM	TO	\*-	IN	ON	AT	SAVE	LETTER/S
+Rule	Swiss	1941	1942	\*-	May	Mon>=1	1:00	1:00	S
+Rule	Swiss	1941	1942	\*-	Oct	Mon>=1	2:00	0	\*-
+.sp .5
+Rule	EU	1977	1980	\*-	Apr	Sun>=1	1:00u	1:00	S
+Rule	EU	1977	only	\*-	Sep	lastSun	1:00u	0	\*-
+Rule	EU	1978	only	\*-	Oct	 1	1:00u	0	\*-
+Rule	EU	1979	1995	\*-	Sep	lastSun	1:00u	0	\*-
+Rule	EU	1981	max	\*-	Mar	lastSun	1:00u	1:00	S
+Rule	EU	1996	max	\*-	Oct	lastSun	1:00u	0	\*-
+.sp
+.ta \w'# Zone\0\0'u +\w'Europe/Zurich\0\0'u +\w'0:29:45.50\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
+# Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
+Zone	Europe/Zurich	0:34:08	\*-	LMT	1853 Jul 16
+		0:29:45.50	\*-	BMT	1894 Jun
+		1:00	Swiss	CE%sT	1981
+		1:00	EU	CE%sT
+.sp
+Link	Europe/Zurich	Europe/Vaduz
+.sp
+.in
+.fi
+In this example, the EU rules are for the European Union
+and for its predecessor organization, the European Communities.
+The timezone is named Europe/Zurich and it has the alias Europe/Vaduz.
+This example says that Zurich was 34 minutes and 8
+seconds east of UT until 1853-07-16 at 00:00, when the legal offset
+was changed to
+7\*d\*_26\*m\*_22.50\*s,
+which works out to 0:29:45.50;
+.B zic
+treats this by rounding it to 0:29:46.
+After 1894-06-01 at 00:00 the UT offset became one hour
+and Swiss daylight saving rules (defined with lines beginning with
+.q "Rule Swiss")
+apply.  From 1981 to the present, EU daylight saving rules have
+applied, and the UTC offset has remained at one hour.
+.PP
+In 1941 and 1942, daylight saving time applied from the first Monday
+in May at 01:00 to the first Monday in October at 02:00.
+The pre-1981 EU daylight-saving rules have no effect
+here, but are included for completeness.  Since 1981, daylight
+saving has begun on the last Sunday in March at 01:00 UTC.
+Until 1995 it ended the last Sunday in September at 01:00 UTC,
+but this changed to the last Sunday in October starting in 1996.
+.PP
+For purposes of display,
+.q "LMT"
+and
+.q "BMT"
+were initially used, respectively.  Since
+Swiss rules and later EU rules were applied, the time zone abbreviation
+has been CET for standard time and CEST for daylight saving
+time.
+.SH FILES
+.TP
+.I /etc/localtime
+Default local timezone file.
+.TP
+.I /usr/share/zoneinfo
+Default timezone information directory.
+.SH NOTES
+For areas with more than two types of local time,
+you may need to use local standard time in the
+.B AT
+field of the earliest transition time's rule to ensure that
+the earliest transition time recorded in the compiled file is correct.
+.PP
+If,
+for a particular timezone,
+a clock advance caused by the start of daylight saving
+coincides with and is equal to
+a clock retreat caused by a change in UT offset,
+.B zic
+produces a single transition to daylight saving at the new UT offset
+without any change in local (wall clock) time.
+To get separate transitions
+use multiple zone continuation lines
+specifying transition instants using universal time.
+.SH SEE ALSO
+.BR tzfile (5),
+.BR zdump (8)