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diff --git a/man5/proc.5 b/man5/proc.5 new file mode 100644 index 000000000..8165ba7d9 --- /dev/null +++ b/man5/proc.5 @@ -0,0 +1,1462 @@ +.\" Copyright (C) 1994, 1995 by Daniel Quinlan (quinlan@yggdrasil.com) +.\" with networking additions from Alan Cox (A.Cox@swansea.ac.uk) +.\" and scsi additions from Michael Neuffer (neuffer@mail.uni-mainz.de) +.\" and sysctl additions from Andries Brouwer (aeb@cwi.nl) +.\" and System V IPC (as well as various other) additions from +.\" Michael Kerrisk (mtk16@ext.canterbury.ac.nz) +.\" +.\" This is free documentation; you can redistribute it and/or +.\" modify it under the terms of the GNU General Public License as +.\" published by the Free Software Foundation; either version 2 of +.\" the License, or (at your option) any later version. +.\" +.\" The GNU General Public License's references to "object code" +.\" and "executables" are to be interpreted as the output of any +.\" document formatting or typesetting system, including +.\" intermediate and printed output. +.\" +.\" This manual is distributed in the hope that it will be useful, +.\" but WITHOUT ANY WARRANTY; without even the implied warranty of +.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.\" GNU General Public License for more details. +.\" +.\" You should have received a copy of the GNU General Public +.\" License along with this manual; if not, write to the Free +.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, +.\" USA. +.\" +.\" Modified 1995-05-17 by faith@cs.unc.edu +.\" Minor changes by aeb and Marty Leisner (leisner@sdsp.mc.xerox.com). +.\" Modified 1996-04-13, 1996-07-22 by aeb@cwi.nl +.\" Modified 2001-12-16 by rwhron@earthlink.net +.\" Modified 2002-07-13 by jbelton@shaw.ca +.\" Modified 2002-07-22, 2003-05-27, 2004-04-06, 2004-05-25 +.\" by Michael Kerrisk <mtk16@ext.canterbury.ac.nz> +.\" +.TH PROC 5 2004-05-25 "" "Linux Programmer's Manual" +.SH NAME +proc \- process information pseudo-filesystem + +.SH DESCRIPTION +The +.I proc +filesystem is a pseudo-filesystem which is used as an interface to +kernel data structures. It is commonly mounted at +.IR /proc . +Most of it is read-only, but some files allow kernel variables to be +changed. +.LP +The following outline gives a quick tour through the /proc hierarchy. +.PD 1 +.TP +.I /proc/[number] +There is a numerical subdirectory for each running process; the +subdirectory is named by the process ID. +Each such subdirectory contains the following +pseudo-files and directories. +.TP +.I /proc/[number]/cmdline +This holds the complete command line for the process, unless the whole +process has been swapped out or the process is a zombie. In +either of these latter cases, there is nothing in this file: i.e. a +read on this file will return 0 characters. +The command line arguments appear in this file as a set of +null-separated strings, with a further null byte after the last string. +.TP +.I /proc/[number]/cwd +This is a link to the current working directory of the process. To find +out +the cwd of process 20, for instance, you can do this: + +.br +.nf +.ft CW +cd /proc/20/cwd; /bin/pwd +.fi +.ft + +Note that the pwd command is often a shell builtin, and might +not work properly. In bash, you may use pwd -P. +.TP +.I /proc/[number]/environ +This file contains the environment for the process. +The entries are separated by null characters, +and there may be a null character at the end. +Thus, to print out the environment of process 1, you would do: + +.br +.nf +.ft CW +(cat /proc/1/environ; echo) | tr "\\000" "\\n" +.fi +.ft P + +(For a reason why one should want to do this, see +.BR lilo (8).) +.TP +.I /proc/[number]/exe +Under Linux 2.2 and later, this file is a symbolic link +containing the actual path name of the executed command. +This symbolic link can be dereferenced normally - attempting to open +it will open the executable. You can even type +.I /proc/[number]/exe +to run another copy of the same process as [number]. + +Under Linux 2.0 and earlier +.I /proc/[number]/exe +is a pointer to the binary which was executed, +and appears as a symbolic link. A +.BR readlink (2) +call on this file under Linux 2.0 returns a string in the format: + +[device]:inode + +For example, [0301]:1502 would be inode 1502 on device major 03 (IDE, +MFM, etc. drives) minor 01 (first partition on the first drive). + +.BR find (1) +with the -inum option can be used to locate the file. +.TP +.I /proc/[number]/fd +This is a subdirectory containing one entry for each file which the +process has open, named by its file descriptor, and which is a +symbolic link to the actual file. Thus, 0 is +standard input, 1 standard output, 2 standard error, etc. + +Programs that will take a filename, but will not take the standard +input, and which write to a file, but will not send their output to +standard output, can be effectively foiled this way, assuming that -i +is the flag designating an input file and -o is the flag designating +an output file: +.br +.nf + +\f(CWfoobar -i /proc/self/fd/0 -o /proc/self/fd/1 ...\fR + +.fi +.br +and you have a working filter. +.\" The following is not true in my tests (MTK): +.\" Note that this will not work for +.\" programs that seek on their files, as the files in the fd directory +.\" are not seekable. + +/proc/self/fd/N is approximately the same as /dev/fd/N in some UNIX +and UNIX-like systems. Most Linux MAKEDEV scripts symbolically link +/dev/fd to /proc/self/fd, in fact. +.TP +.I /proc/[number]/maps +A file containing the currently mapped memory regions and their access +permissions. + +The format is: + +.nf +.ft CW +.in 8n +address perms offset dev inode pathname +08048000-08056000 r-xp 00000000 03:0c 64593 /usr/sbin/gpm +08056000-08058000 rw-p 0000d000 03:0c 64593 /usr/sbin/gpm +08058000-0805b000 rwxp 00000000 00:00 0 +40000000-40013000 r-xp 00000000 03:0c 4165 /lib/ld-2.2.4.so +40013000-40015000 rw-p 00012000 03:0c 4165 /lib/ld-2.2.4.so +4001f000-40135000 r-xp 00000000 03:0c 45494 /lib/libc-2.2.4.so +40135000-4013e000 rw-p 00115000 03:0c 45494 /lib/libc-2.2.4.so +4013e000-40142000 rw-p 00000000 00:00 0 +bffff000-c0000000 rwxp 00000000 00:00 0 +.ft +.fi +.in + +where address is the address space in the process that it occupies, +perms is a set of permissions: + +.nf +.in +5 +r = read +w = write +x = execute +s = shared +p = private (copy on write) +.fi +.in + +offset is the offset into the file/whatever, dev is the device +(major:minor), and inode is the inode on that device. 0 indicates +that no inode is associated with the memory region, as the case would +be with bss. + +Under Linux 2.0 there is no field giving pathname. +.TP +.I /proc/[number]/mem +This file can be used to access the pages of a process's memory through +.BR open (2), +.BR read (2), +and +.BR fseek (3). +.TP +.I /proc/[number]/root +Unix and Linux support the idea of a per-process root of the +filesystem, set by the +.BR chroot (2) +system call. This file is a symbolic link that points to the process's +root directory, and behaves as exe, fd/*, etc. do. +.TP +.I /proc/[number]/stat +Status information about the process. This is used by +.BR ps (1). +It is defined in +.IR /usr/src/linux/fs/proc/array.c "." + +The fields, in order, with their proper +.BR scanf (3) +format specifiers, are: +.RS +.TP +\fIpid\fP %d +The process id. +.TP +\fIcomm\fP %s +The filename of the executable, in parentheses. This is visible +whether or not the executable is swapped out. +.TP +\fIstate\fP %c +One character from the string "RSDZTW" where R is running, S is +sleeping in an interruptible wait, D is waiting in uninterruptible +disk sleep, Z is zombie, T is traced or stopped (on a signal), +and W is paging. +.TP +\fIppid\fP %d +The PID of the parent. +.TP +\fIpgrp\fP %d +The process group ID of the process. +.TP +\fIsession\fP %d +The session ID of the process. +.TP +.\" tty_nr needs better explanation. +\fItty_nr\fP %d +The tty the process uses. +.TP +\fItpgid\fP %d +.\" This field and following, up to and including wchan added 0.99.1 +The process group ID of the process which currently owns the tty that +the process is connected to. +.TP +\fIflags\fP %lu +The kernel flags word of the process. For bit meanings, +see the PF_* defines in +.IR <linux/sched.h> . +Details depend on the kernel version. +.TP +\fIminflt\fP %lu +The number of minor faults the process has made which have not +required loading a memory page from disk. +.TP +\fIcminflt\fP %lu +The number of minor faults that the process's +waited-for children have made. +.TP +\fImajflt\fP %lu +The number of major faults the process has made which have +required loading a memory page from disk. +.TP +\fIcmajflt\fP %lu +The number of major faults that the process's +waited-for children have made. +.TP +\fIutime\fP %lu +The number of jiffies that this process has been scheduled in user +mode. +.TP +\fIstime\fP %lu +The number of jiffies that this process has been scheduled in kernel +mode. +.TP +\fIcutime\fP %ld +The number of jiffies that this process's +waited-for children have been scheduled in user mode. (See also +.BR times (2).) +.TP +\fIcstime\fP %ld +The number of jiffies that this process's +waited-for children have been scheduled in kernel mode. +.TP +\fIpriority\fP %ld +The standard nice value, plus fifteen. The value is never negative in +the kernel. +.TP +\fInice\fP %ld +The nice value ranges from 19 (nicest) to -19 (not nice to others). +.TP +.\" .TP +.\" \fIcounter\fP %ld +.\" The current maximum size in jiffies of the process's next timeslice, +.\" or what is currently left of its current timeslice, if it is the +.\" currently running process. +.\" .TP +.\" \fItimeout\fP %u +.\" The time in jiffies of the process's next timeout. +\fI0\fP %ld +This value is hard coded to 0 as a placeholder for a removed field. +.TP +\fIitrealvalue\fP %ld +The time in jiffies before the next SIGALRM is sent to the process +due to an interval timer. +.TP +\fIstarttime\fP %lu +The time in jiffies the process started after system boot. +.TP +\fIvsize\fP %lu +Virtual memory size in bytes. +.TP +\fIrss\fP %ld +Resident Set Size: number of pages the process has in real memory, +minus 3 for administrative purposes. This is just the pages which +count towards text, data, or stack space. This does not include pages +which have not been demand-loaded in, or which are swapped out. +.TP +\fIrlim\fP %lu +Current limit in bytes on the rss of the process (usually +4294967295 on i386). +.TP +\fIstartcode\fP %lu +The address above which program text can run. +.TP +\fIendcode\fP %lu +The address below which program text can run. +.TP +\fIstartstack\fP %lu +The address of the start of the stack. +.TP +\fIkstkesp\fP %lu +The current value of esp (stack pointer), as found in the +kernel stack page for the process. +.TP +\fIkstkeip\fP %lu +The current EIP (instruction pointer). +.TP +\fIsignal\fP %lu +The bitmap of pending signals (usually 0). +.TP +\fIblocked\fP %lu +The bitmap of blocked signals (usually 0, 2 for shells). +.TP +\fIsigignore\fP %lu +The bitmap of ignored signals. +.TP +\fIsigcatch\fP %lu +The bitmap of catched signals. +.TP +\fIwchan\fP %lu +This is the "channel" in which the process is waiting. It is the +address of a system call, and can be looked up in a namelist if you +need a textual name. (If you have an up-to-date /etc/psdatabase, then +try \fIps -l\fP to see the WCHAN field in action.) +.TP +\fInswap\fP %lu +Number of pages swapped - not maintained. +.TP +\fIcnswap\fP %lu +Cumulative \fInswap\fP for child processes. +.TP +\fIexit_signal\fP %d +Signal to be sent to parent when we die. +.TP +\fIprocessor\fP %d +CPU number last executed on. +.RE +.TP +.I /proc/[number]/statm +Provides information about memory status in pages. The columns are: + size total program size + resident resident set size + share shared pages + trs text (code) + drs data/stack + lrs library + dt dirty pages +.TP +.I /proc/[number]/status +Provides much of the information in +.I /proc/[number]/stat +and +.I /proc/[number]/statm +in a format that's easier for humans to parse. +.TP +.I /proc/apm +Advanced power management version and battery information +when CONFIG_APM is defined at kernel compilation time. +.TP +.I /proc/bus +Contains subdirectories for installed busses. +.TP +.I /proc/bus/pccard +Subdirectory for pcmcia devices when CONFIG_PCMCIA is set +at kernel compilation time. +.TP +.I /proc/bus/pccard/drivers +.TP +.I /proc/bus/pci +Contains various bus subdirectories and pseudo-files containing +information about pci busses, installed devices, and device +drivers. Some of these files are not ASCII. +.TP +.I /proc/bus/pci/devices +Information about pci devices. They may be accessed through +.BR lspci (8) +and +.BR setpci (8). +.TP +.I /proc/cmdline +Arguments passed to the Linux kernel at boot time. Often done via +a boot manager such as +.BR lilo (1). +.TP +.I /proc/cpuinfo +This is a collection of CPU and system architecture dependent items, +for each supported architecture a different list. +Two common entries are \fIprocessor\fP which gives CPU number and +\fIbogomips\fP; a system constant that is calculated +during kernel initialization. SMP machines have information for +each CPU. +.TP +.I /proc/devices +Text listing of major numbers and device groups. This can be used by +MAKEDEV scripts for consistency with the kernel. +.TP +.IR /proc/diskstats " (since Linux 2.5.69)" +This file contains disk I/O statistics for each disk device. +See the kernel source file +.I Documentation/iostats.txt +for further information. +.TP +.I /proc/dma +This is a list of the registered \fIISA\fP DMA (direct memory access) +channels in use. +.TP +.I /proc/driver +Empty subdirectory. +.TP +.I /proc/execdomains +List of the execution domains (ABI personalities). +.TP +.I /proc/fb +Frame buffer information when CONFIG_FB is defined during kernel +compilation. +.TP +.I /proc/filesystems +A text listing of the filesystems which were compiled into the kernel. +Incidentally, this is used by +.BR mount (1) +to cycle through different filesystems when none is specified. +.TP +.I /proc/fs +Empty subdirectory. +.TP +.I /proc/ide +This directory +exists on systems with the ide bus. There are directories for each +ide channel and attached device. Files include: + +.nf +cache buffer size in KB +capacity number of sectors +driver driver version +geometry physical and logical geometry +identify in hexidecimal +media media type +model manufacturer's model number +settings drive settings +smart_thresholds in hexidecimal +smart_values in hexidecimal +.fi + +The +.BR hdparm (8) +utility provides access to this information in a friendly format. +.TP +.I /proc/interrupts +This is used to record the number of interrupts per each IRQ on (at +least) the i386 architechure. Very easy to read formatting, done in +ASCII. +.TP +.I /proc/iomem +I/O memory map in Linux 2.4. +.TP +.I /proc/ioports +This is a list of currently registered Input-Output port regions that +are in use. +.TP +.IR /proc/kallsyms " (since Linux 2.5.71)" +This holds the kernel exported symbol definitions used by the +.BR modules (X) +tools to dynamically link and bind loadable modules. +In Linux 2.5.47 and earlier, a similar file with slightly different syntax +was named +.IR ksyms . +.TP +.I /proc/kcore +This file represents the physical memory of the system and is stored +in the ELF core file format. With this pseudo-file, and an unstripped +kernel (/usr/src/linux/vmlinux) binary, GDB can be used to +examine the current state of any kernel data structures. + +The total length of the file is the size of physical memory (RAM) plus +4KB. +.TP +.I /proc/kmsg +This file can be used instead of the +.BR syslog (2) +system call to read kernel messages. A process must have superuser +privileges to read this file, and only one process should read this +file. This file should not be read if a syslog process is running +which uses the +.BR syslog (2) +system call facility to log kernel messages. + +Information in this file is retrieved with the +.BR dmesg (8) +program. +.TP +.IR /proc/ksyms " (Linux 1.1.23-2.5.47)" +See +.IR /proc/kallsyms . +.TP +.I /proc/loadavg +The load average numbers give the number of jobs in the run queue (state +R) +or waiting for disk I/O (state D) averaged over 1, 5, and 15 minutes. +They are the same as the load average numbers given by +.BR uptime (1) +and other programs. +.TP +.I /proc/locks +This file shows current file locks +.RB ( flock "(2) and " fcntl (2)) +and leases +.RB ( fcntl (2)). +.TP +.I /proc/malloc +This file is only present if CONFIGDEBUGMALLOC was defined during +compilation. +.TP +.I /proc/meminfo +This is used by +.BR free (1) +to report the amount of free and used memory (both physical and swap) +on the system as well as the shared memory and buffers used by the +kernel. + +It is in the same format as +.BR free (1), +except in bytes rather than KB. +.TP +.I /proc/mounts +This is a list of all the file systems currently mounted on the system. +The format of this file is documented in +.IR fstab (5). +.TP +.I /proc/modules +A text list of the modules that have been loaded by the system. +See also +.BR lsmod (8). +.TP +.I /proc/mtrr +Memory Type Range Registers. +See +.I /usr/src/linux/Documentation/mtrr.txt +for details. +.TP +.I /proc/net +various net pseudo-files, all of which give the status of some part of +the networking layer. These files contain ASCII structures and are, +therefore, readable with cat. However, the standard +.BR netstat (8) +suite provides much cleaner access to these files. +.TP +.I /proc/net/arp +This holds an ASCII readable dump of the kernel ARP table used for +address resolutions. It will show both dynamically learned and +pre-programmed ARP entries. The format is: + +.nf +.ft CW +.in 8n +IP address HW type Flags HW address Mask Device +192.168.0.50 0x1 0x2 00:50:BF:25:68:F3 * eth0 +192.168.0.250 0x1 0xc 00:00:00:00:00:00 * eth0 +.ft +.fi +.in + +Here 'IP address' is the IPv4 address of the machine and the 'HW type' +is the hardware type of the address from RFC 826. The flags are the internal +flags of the ARP structure (as defined in /usr/include/linux/if_arp.h) and +the 'HW address' is the data link layer mapping for that IP address if +it is known. +.TP +.I /proc/net/dev +The dev pseudo-file contains network device status information. This gives +the number of received and sent packets, the number of errors and +collisions +and other basic statistics. These are used by the +.BR ifconfig (8) +program to report device status. The format is: + +.nf +.ft CW +.in 1n +Inter-| Receive | Transmit + face |bytes packets errs drop fifo frame compressed multicast|bytes packets errs drop fifo colls carrier compressed + lo: 2776770 11307 0 0 0 0 0 0 2776770 11307 0 0 0 0 0 0 + eth0: 1215645 2751 0 0 0 0 0 0 1782404 4324 0 0 0 427 0 0 + ppp0: 1622270 5552 1 0 0 0 0 0 354130 5669 0 0 0 0 0 0 + tap0: 7714 81 0 0 0 0 0 0 7714 81 0 0 0 0 0 0 +.in +.ft +.fi +.\" .TP +.\" .I /proc/net/ipx +.\" No information. +.\" .TP +.\" .I /proc/net/ipx_route +.\" No information. +.TP +.I /proc/net/dev_mcast +Defined in +.IR /usr/src/linux/net/core/dev_mcast.c : +.nf +.in +5 +indx ifterface_name dmi_u dmi_g dmi_address +2 eth0 1 0 01005e000001 +3 eth1 1 0 01005e000001 +4 eth2 1 0 01005e000001 +.in +.fi +.TP +.I /proc/net/igmp +Internet Group Management Protocol. Defined in +.IR /usr/src/linux/net/core/igmp.c . +.TP +.I /proc/net/rarp +This file uses the same format as the +.I arp +file and contains the current reverse mapping database used to provide +.BR rarp (8) +reverse address lookup services. If RARP is not configured into the +kernel, +this file will not be present. +.TP +.I /proc/net/raw +Holds a dump of the RAW socket table. Much of the information is not of +use +apart from debugging. The 'sl' value is the kernel hash slot for the +socket, +the 'local address' is the local address and protocol number pair."St" is +the internal status of the socket. The "tx_queue" and "rx_queue" are the +outgoing and incoming data queue in terms of kernel memory usage. +The "tr", "tm->when", and "rexmits" fields are not used by RAW. +The uid field holds the creator euid of the socket. +.\" .TP +.\" .I /proc/net/route +.\" No information, but looks similar to +.\" .BR route (8). +.TP +.I /proc/net/snmp +This file holds the ASCII data needed for the IP, ICMP, TCP, and UDP +management +information bases for an snmp agent. +.TP +.I /proc/net/tcp +Holds a dump of the TCP socket table. Much of the information is not +of use apart from debugging. The "sl" value is the kernel hash slot +for the socket, the "local address" is the local address and port number pair. +The "remote address" is the remote address and port number pair +(if connected). 'St' is the internal status of the socket. +The 'tx_queue' and 'rx_queue' are the +outgoing and incoming data queue in terms of kernel memory usage. +The "tr", "tm->when", and "rexmits" fields hold internal information of +the kernel socket state and are only useful for debugging. The uid field +holds the creator euid of the socket. +.TP +.I /proc/net/udp +Holds a dump of the UDP socket table. Much of the information is not of +use apart from debugging. The "sl" value is the kernel hash slot for the +socket, the "local address" is the local address and port number pair. +The "remote address" is the remote address and port number pair +(if connected). "St" is the internal status of the socket. +The "tx_queue" and "rx_queue" are the outgoing and incoming data queue +in terms of kernel memory usage. The "tr", "tm->when", and "rexmits" fields +are not used by UDP. The uid field holds the creator euid of the socket. +The format is: + +.nf +.ft CW +.in 1n +sl local_address rem_address st tx_queue rx_queue tr rexmits tm->when uid + 1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0 + 1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0 + 1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 +.in +.ft +.fi +.TP +.I /proc/net/unix +Lists the UNIX domain sockets present within the system and their +status. The format is: +.nf +.sp .5 +.ft CW +Num RefCount Protocol Flags Type St Path + 0: 00000002 00000000 00000000 0001 03 + 1: 00000001 00000000 00010000 0001 01 /dev/printer +.ft +.sp .5 +.fi + +Here 'Num' is the kernel table slot number, 'RefCount' is the number +of users of the socket, 'Protocol' is currently always 0, 'Flags' +represent the internal kernel flags holding the status of the +socket. Currently, type is always '1' (Unix domain datagram sockets are +not yet supported in the kernel). 'St' is the internal state of the +socket and Path is the bound path (if any) of the socket. +.TP +.I /proc/partitions +Contains major and minor numbers of each partition as well as number +of blocks and partition name. +.TP +.I /proc/pci +This is a listing of all PCI devices found during kernel initialization +and their configuration. +.TP +.I /proc/scsi +A directory with the scsi midlevel pseudo-file and various SCSI lowlevel +driver +directories, which contain a file for each SCSI host in this system, all +of +which give the status of some part of the SCSI IO subsystem. +These files contain ASCII structures and are, therefore, readable with +cat. + +You can also write to some of the files to reconfigure the subsystem or +switch +certain features on or off. +.TP +.I /proc/scsi/scsi +This is a listing of all SCSI devices known to the kernel. The listing is +similar to the one seen during bootup. +scsi currently supports only the \fIadd-single-device\fP command which +allows +root to add a hotplugged device to the list of known devices. + +An +.B echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi +will cause +host scsi1 to scan on SCSI channel 0 for a device on ID 5 LUN 0. If there +is already a device known on this address or the address is invalid, an +error will be returned. +.TP +.I /proc/scsi/[drivername] +\fI[drivername]\fP can currently be NCR53c7xx, aha152x, aha1542, aha1740, +aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000, pas16, qlogic, +scsi_debug, seagate, t128, u15-24f, ultrastore, or wd7000. +These directories show up for all drivers that registered at least one +SCSI +HBA. Every directory contains one file per registered host. Every +host-file is named after the number the host was assigned during +initialization. + +Reading these files will usually show driver and host configuration, +statistics etc. + +Writing to these files allows different things on different hosts. +For example, with the \fIlatency\fP and \fInolatency\fP commands, +root can switch on and off command latency measurement code in the +eata_dma driver. With the \fIlockup\fP and \fIunlock\fP commands, +root can control bus lockups simulated by the scsi_debug driver. +.TP +.I /proc/self +This directory refers to the process accessing the /proc filesystem, +and is identical to the /proc directory named by the process ID of the +same process. +.TP +.I /proc/slabinfo +Information about kernel caches. The columns are: +.nf +cache-name +num-active-objs +total-objs +object-size +num-active-slabs +total-slabs +num-pages-per-slab +.fi +See +.BR slabinfo (5) +for details. +.TP +.I /proc/stat +kernel/system statistics. Varies with architecture. Common +entries include: +.RS +.TP +\fIcpu 3357 0 4313 1362393\fP +The number of jiffies (1/100ths of a second) that the system spent in +user mode, user mode with low priority (nice), system mode, and the +idle task, respectively. The last value should be 100 times the +second entry in the uptime pseudo-file. +.TP +\fIpage 5741 1808\fP +The number of pages the system paged in and the number that were paged +out (from disk). +.TP +\fIswap 1 0\fP +The number of swap pages that have been brought in and out. +.TP +\fIintr 1462898\fP +The number of interrupts received from the system boot. +.TP +\fIdisk_io: (2,0):(31,30,5764,1,2) (3,0):\fP... +(major,minor):(noinfo, read_io_ops, blks_read, write_io_ops, blks_written) +.TP +\fIctxt 115315\fP +The number of context switches that the system underwent. +.TP +\fIbtime 769041601\fP +boot time, in seconds since the epoch (January 1, 1970). +.TP +\fIprocesses 86031\fP +Number of forks since boot. +.RE +.TP +.I /proc/swaps +Swap areas in use. See also +.BR swapon (8). +.TP +.I /proc/sys +This directory (present since 1.3.57) contains a number of files +and subdirectories corresponding to kernel variables. +These variables can be read and sometimes modified using +the \fIproc\fP file system, and the +.BR sysctl (2) +system call. Presently, there are subdirectories +.IR abi ", " debug ", " dev ", " fs ", " kernel ", " net ", " proc ", " +.IR rxrpc ", " sunrpc " and " vm +that each contain more files and subdirectories. +.TP +.I /proc/sys/abi +This directory may contain files with application binary information. +On some systems, it is not present. +.TP +.I /proc/sys/debug +This directory may be empty. +.TP +.I /proc/sys/dev +This directory contains device specific information (eg dev/cdrom/info). +On +some systems, it may be empty. +.TP +.I /proc/sys/fs +This contains the subdirectory +.IR binfmt_misc +and files +.IR dentry-state ", " dir-notify-enable ", " dquot-nr ", " file-max ", " +.IR file-nr ", " inode-max ", " inode-nr ", " inode-state ", " +.IR lease-break-time ", " leases-enable ", " overflowgid ", " overflowuid +.IR super-max " and " super-nr +with function fairly clear from the name. +.TP +.I /proc/sys/fs/binfmt_misc +Documentation for files in this directory can in the kernel sources in +.IR Documentation/binfmt_misc.txt . +.TP +.I /proc/sys/fs/dentry-state +This file contains six numbers, +.IR nr_dentry ", " nr_unused ", " age_limit " (age in seconds), " +want_pages +(pages requested by system) and two dummy values. +nr_dentry seems to be 0 all the time. +nr_unused seems to be the number of unused dentries. +age_limit is the age in seconds after which dcache entries +can be reclaimed when memory is short and want_pages is +nonzero when the kernel has called shrink_dcache_pages() and the +dcache isn't pruned yet. +.TP +.I /proc/sys/fs/dir-notify-enable +This file can be used to disable or enable the +.I dnotify +interface described in +.BR fcntl (2) +on a system-wide basis. +A value of 0 in this file disables the interface, +and a value of 1 enables it. +.TP +.I /proc/sys/fs/dquot-max +This file shows the maximum number of cached disk quota entries. +On some (2.4) systems, it is not present. +If the number of free cached disk quota entries is very low and +you have some awesome number of simultaneous system users, +you might want to raise the limit. +.TP +.I /proc/sys/fs/dquot-nr +This file shows the number of allocated disk quota +entries and the number of free disk quota entries. +.TP +.I /proc/sys/fs/file-max +This file defines +a system-wide limit on the number of open files for all processes. +(See also +.BR setrlimit (2), +which can be used by a process to set the per-process limit, +.BR RLIMIT_NOFILE , +on the number of files it may open.) +If you get lots +of error messages about running out of file handles, +try increasing this value: +.br + +.br +.nf +.ft CW +echo 100000 > /proc/sys/fs/file-max +.fi +.ft + +The kernel constant +.I NR_OPEN +imposes an upper limit on the value that may be placed in +.IR file-max . + +If you increase +.IR /proc/sys/fs/file-max "," +be sure to increase +.I /proc/sys/fs/inode-max +to 3-4 times the new +value of +.IR /proc/sys/fs/file-max "," +or you will run out of inodes. +.TP +.I /proc/sys/fs/file-nr +This (read-only) file +gives the number of files presently opened. +It contains three numbers: The number of allocated +file handles, the number of free file handles and the maximum +number of file handles. The kernel allocates file handles dynamically, +but it +doesn't free them again. If the number of allocated files is close to the + +maximum, you should consider increasing the maximum. +When the number of free file handles is +large, you've encountered a peak in your usage of file +handles and you probably don't need to increase the maximum. +.TP +.I /proc/sys/fs/inode-max +This file contains the maximum number of in-memory inodes. +On some (2.4) systems, it may not be +present. This value should be 3-4 times larger +than the value in file-max, since stdin, stdout and network sockets also +need an inode to handle them. When you regularly run +out of inodes, you need to increase this value. +.TP +.I /proc/sys/fs/inode-nr +This file contains the first two values from inode-state. +.TP +.I /proc/sys/fs/inode-state +This file +contains seven numbers: nr_inodes, nr_free_inodes, preshrink and four +dummy +values. +nr_inodes is the number of inodes the system has +allocated. This can be slightly more than inode-max because +Linux allocates them one pageful at a time. +nr_free_inodes represents the number of free inodes. +preshrink is nonzero when the nr_inodes > inode-max and the +system needs to prune the inode list instead of allocating +more. +.TP +.I /proc/sys/fs/lease-break-time +This file +specifies the grace period that the kernel grants to a process +holding a file lease +.RB ( fcntl (2)) +after it has sent a signal to that process notifying it +that another process is waiting to open the file. +If the lease holder does not remove or downgrade the lease within +this grace period, the kernel forcibly breaks the lease. +.TP +.I /proc/sys/fs/leases-enable +This file can be used to enable or disable file leases +.RB ( fcntl (2)) +on a system-wide basis. +If this file contains the value 0, leases are disabled. +A non-zero value enables leases. +.TP +.IR /proc/sys/fs/overflowgid " and " /proc/sys/fs/overflowuid +These files +allow you to change the value of the fixed UID and GID. +The default is 65534. +Some filesystems only support 16-bit UIDs and GIDs, although in Linux +UIDs and GIDs are 32 bits. When one of these filesystems is mounted +with writes enabled, any UID or GID that would exceed 65535 is translated +to the overflow value before being written to disk. +.TP +.I /proc/sys/fs/super-max +This file +controls the maximum number of superblocks, and +thus the maximum number of mounted filesystems the kernel +can have. You only need to increase super-max if you need to +mount more filesystems than the current value in super-max +allows you to. +.TP +.I /proc/sys/fs/super-nr +This file +contains the number of filesystems currently mounted. +.TP +.I /proc/sys/kernel +This directory contains files +.IR acct ", " cad_pid ", " cap-bound ", " +.IR core_pattern ", " core_uses_pid ", " +.IR ctrl-alt-del ", " dentry-state ", " domainname ", " +.IR hotplug ", " hostname ", " +.IR htab-reclaim " (PowerPC only), " +.IR java-appletviewer " (binfmt_java, obsolete), " +.IR java-interpreter " (binfmt_java, obsolete), " l2cr " (PowerPC only), " +.IR modprobe ", " msgmax ", " msgmnb ", " +.IR msgmni ", " osrelease ", " ostype ", " overflowgid ", " overflowuid , +.IR panic ", " panic_on_oops ", " pid_max ", " +.IR powersave-nap " (PowerPC only), " printk ", " pty ", " random ", " +.IR real-root-dev ", " reboot-cmd " (SPARC only), " rtsig-max ", " +.IR rtsig-nr ", " sem ", " sg-big-buff ", " +.IR shmall ", " shmmax ", " shmmni ", " sysrq ", " tainted ", " threads-max , +.IR version " and " zero-paged " (PowerPC only) " +with function fairly clear from the name. +.TP +.I /proc/sys/kernel/acct +This file +contains three numbers: highwater, lowwater and frequency. +If BSD-style process accounting is enabled these values control +its behaviour. If free space on filesystem where the log lives +goes below lowwater percent accounting suspends. If free space gets +above highwater percent accounting resumes. Frequency determines +how often the kernel checks the amount of free space (value is in +seconds). Default values are 4, 2 and 30. +That is, suspend accounting if <= 2% of space is free; resume it +if >= 4% of space is free; consider information about amount of free space +valid for 30 seconds. +.TP +.I /proc/sys/kernel/cap-bound +This file holds the value of the kernel +.IR "capability bounding set" +(expressed as a signed decimal number). +This set is ANDed against the capabilities permitted to a process +during exec. +.TP +.I /proc/sys/kernel/core_pattern +This file +(new in Linux 2.5) provides finer control over the form of +a core filename than the obsolete +.IR /proc/sys/kernel/core_uses_pid +file described below. +The name for a core file is controlled by defining a template in +.IR /proc/sys/kernel/core_pattern . +The template can contain % specifiers which are substituted +by the following values when a core file is created: +.nf + + %% A single % character + %p PID of dumped process + %u real UID of dumped process + %g real GID of dumped process + %s number of signal causing dump + %t time of dump (secs since 0:00h, 1 Jan 1970) + %h hostname (same as the 'nodename' + returned by \fBuname\fP(2)) + %e executable filename + +.fi +A single % at the end of the template is dropped from the +core filename, as is the combination of a % followed by any +character other than those listed above. +All other characters in the template become a literal +part of the core filename. +The maximum size of the resulting core filename is 64 bytes. +The default value in this file is "core". +For backward compatibility, if +.I /proc/sys/kernel/core_pattern +does not include "%p" and +.I /proc/sys/kernel/core_uses_pid +is non-zero, then .PID will be appended to the core filename. +.TP +.I /proc/sys/kernel/core_uses_pid +This file +can be used control the naming of a core dump file on Linux 2.4. +If this file contains the value 0, then a core dump file is simply named +.IR core . +If this file contains a non-zero value, then the core dump file includes +the process ID in a name of the form +.IR core.PID . +.TP +.I /proc/sys/kernel/ctrl-alt-del +This file +controls the handling of Ctrl-Alt-Del from the keyboard. +When the value in this file is 0, Ctrl-Alt-Del is trapped and +sent to the +.BR init (1) +program to handle a graceful restart. +When the value is > 0, Linux's reaction to a Vulcan +Nerve Pinch (tm) will be an immediate reboot, without even +syncing its dirty buffers. +Note: when a program (like dosemu) has the keyboard in 'raw' +mode, the ctrl-alt-del is intercepted by the program before it +ever reaches the kernel tty layer, and it's up to the program +to decide what to do with it. +.TP +.I /proc/sys/kernel/hotplug +This file +contains the path for the hotplug policy agent. +The default value in this file "/sbin/hotplug". +.TP +.IR /proc/sys/kernel/domainname " and " /proc/sys/kernel/hostname +can be used to set the NIS/YP domainname and the +hostname of your box in exactly the same way as the commands +domainname and hostname, i.e.: +.br + +.br +# echo "darkstar" > /proc/sys/kernel/hostname +.br +# echo "mydomain" > /proc/sys/kernel/domainname +.br + +.br +has the same effect as +.br + +.br +# hostname "darkstar" +.br +# domainname "mydomain" +.br + +.br +Note, however, that the classic darkstar.frop.org has the +hostname "darkstar" and DNS (Internet Domain Name Server) +domainname "frop.org", not to be confused with the NIS (Network +Information Service) or YP (Yellow Pages) domainname. These two +domain names are in general different. For a detailed discussion +see the +.BR hostname (1) +man page. +.TP +.I /proc/sys/kernel/htab-reclaim +(PowerPC only) If this file is set to a non-zero value, +the PowerPC htab +(see kernel file Documentation/powerpc/ppc_htab.txt) is pruned +each time the system hits the idle loop. +.TP +.I /proc/sys/kernel/l2cr +(PowerPC only) This file +contains a flag that controls the L2 cache of G3 processor +boards. If 0, the cache is disabled. Enabled if nonzero. +.TP +.I /proc/sys/kernel/modprobe +This file +is described by the kernel source file Documentation/kmod.txt. +.TP +.I /proc/sys/kernel/msgmax +This file defines +a system-wide limit specifying the maximum number of bytes in +a single message written on a System V message queue. +.TP +.I /proc/sys/kernel/msgmni +This file defines the system-wide limit on the number of +message queue identifiers. +(This file is only present in Linux 2.4 onwards.) +.TP +.I /proc/sys/kernel/msgmnb +This file defines a system-wide paramter used to initialise the +.I msg_qbytes +setting for subsequenly created message queues. +The +.I msg_qbytes +setting specifies the maximum number of bytes that may be written to the +message queue. +.TP +.IR /proc/sys/kernel/ostype " and " /proc/sys/kernel/osrelease +These files +give substrings of +.IR /proc/version . +.TP +.IR /proc/sys/kernel/overflowgid " and " /proc/sys/kernel/overflowuid +These files duplicate the files +.I /proc/sys/fs/overflowgid +and +.IR /proc/sys/fs/overflowuid . +.TP +.I /proc/sys/kernel/panic +gives read/write access to the kernel variable +.IR panic_timeout . +If this is zero, the kernel will loop on a panic; if nonzero +it indicates that the kernel should autoreboot after this number +of seconds. When you use the +software watchdog device driver, the recommended setting is 60. +.TP +.I /proc/sys/kernel/panic_on_oops +This file (new in Linux 2.5) controls the kernel's behaviour when an oops +or +BUG is encountered. If this file contains 0, then the system +tries to continue operation. If it contains 1, then the system +delays a few seconds (to give klogd time to record the oops output) +and then panics. +If the +.I /proc/sys/kernel/panic +file is also non-zero then the machine will be rebooted. +.TP +.I /proc/sys/kernel/pid_max +This file +(new in Linux 2.5) +specifies the value at which PIDs wrap around +(i.e., the value in this file is one greater than the maximum PID). +The default value for this file, 32768, +results in the same range of PIDs as on earlier kernels. +The value in this file can be set to any value up to 2^22 +(PID_MAX_LIMIT, approximately 4 million). +.TP +.IR /proc/sys/kernel/powersave-nap " (PowerPC only)" +This file +contains a flag. If set, Linux-PPC will use the 'nap' mode of +powersaving, +otherwise the 'doze' mode will be used. +.TP +.I /proc/sys/kernel/printk +The four values in this file +are console_loglevel, default_message_loglevel, minimum_console_level and +default_console_loglevel. +These values influence printk() behavior when printing or +logging error messages. See +.BR syslog (2) +for more info on the different loglevels. +Messages with a higher priority than +console_loglevel will be printed to the console. +Messages without an explicit priority +will be printed with priority default_message_level. +minimum_console_loglevel is the minimum (highest) value to which +console_loglevel can be set. +default_console_loglevel is the default value for console_loglevel. +.TP +.IR /proc/sys/kernel/pty " (since Linux 2.6.4)" +This directory +contains two files relating to the number of Unix 98 +pseudo-terminals (see +.BR pts (4)) +on the system. +.TP +.I /proc/sys/kernel/pty/max +This file defines the maximum number of pseudo-terminals. +.TP +.I /proc/sys/kernel/pty/nr +This read-only file +indicates how many pseudo-terminals are currently in use. +.TP +.\" FIXME say more about random +.I /proc/sys/kernel/random +This directory +contains various parameters controlling the operation of the file +.IR /dev/random . +.TP +.I /proc/sys/kernel/real-root-dev +This file +is documented in the kernel source file Documentation/initrd.txt. +.TP +.IR /proc/sys/kernel/reboot-cmd " (Sparc only) " +This file seems to be a way to give an argument to the SPARC +ROM/Flash boot loader. Maybe to tell it what to do after +rebooting? +.TP +.I /proc/sys/kernel/rtsig-max +This file can be used to tune the maximum number +of POSIX realtime (queued) signals that can be outstanding +in the system. +.TP +.I /proc/sys/kernel/rtsig-nr +This file shows the number POSIX realtime signals currently queued. +.TP +.IR /proc/sys/kernel/sem " (since Linux 2.4)" +This file contains 4 numbers defining limits for System V IPC semaphores. +These fields are, in order: +.RS +.IP SEMMSL 8 +The maximum semaphores per semaphore set. +.IP SEMMNS 8 +A system-wide limit on the number of semaphores in all semaphore sets. +.IP SEMOPM 8 +The maximum number of operations that may be specified in a +.BR semop (2) +call. +.IP SEMMNI 8 +A system-wide limit on the maximum number of semaphore identifiers. +.RE +.TP +.I /proc/sys/kernel/sg-big-buff +This file +shows the size of the generic SCSI device (sg) buffer. +You can't tune it just yet, but you could change it on +compile time by editing include/scsi/sg.h and changing +the value of SG_BIG_BUFF. However, there shouldn't be any reason to +change +this value. +.TP +.I /proc/sys/kernel/shmall +This file +contains the system-wide limit on the total number of pages of +System V shared memory. +.TP +.I /proc/sys/kernel/shmmax +This file +can be used to query and set the run time limit +on the maximum (System V IPC) shared memory segment size that can be +created. +Shared memory segments up to 1Gb are now supported in the +kernel. This value defaults to SHMMAX. +.TP +.I /proc/sys/kernel/shmmni +(available in Linux 2.4 and onwards) +This file +specifies the system-wide maximum number of System V shared memory +segments that can be created. +.TP +.I /proc/sys/kernel/version +contains a string like: +.br + +.br +#5 Wed Feb 25 21:49:24 MET 1998.TP +.br + +.br +The '#5' means that +this is the fifth kernel built from this source base and the +date behind it indicates the time the kernel was built. +.TP +.IR /proc/sys/kernel/zero-paged " (PowerPC only) " +This file +contains a flag. When enabled (non-zero), Linux-PPC will pre-zero pages in +the idle loop, possibly speeding up get_free_pages. +.TP +.I /proc/sys/net +This directory contains networking stuff. +.TP +.I /proc/sys/proc +This directory may be empty. +.TP +.I /proc/sys/sunrpc +This directory supports Sun remote procedure call for network file system +(NFS). On some systems, it is not present. +.TP +.I /proc/sys/vm +This directory contains files for memory management tuning, buffer and +cache +management. +.TP +.I /proc/sys/vm/overcommit_memory +This file contains the kernel virtual memory accounting mode. Values are: +.br +0: heuristic overcommit (this is the default) +.br +1: always overcommit, never check +.br +2: always check, never overcommit +.br +In mode 0, calls of +.BR mmap (2) +with MAP_NORESERVE set are not checked, and the default check is very weak, +leading to the risk of getting a process "OOM-killed". +Under Linux 2.4 any nonzero value implies mode 1. +In mode 2 (available since Linux 2.6), the total virtual address space +on the system is limited to (SS + RAM*(r/100)), +where SS is the size of the swap space, and RAM +is the size of the physical memory, and r is the contents of the file +.IR /proc/sys/vm/overcommit_ratio . +.TP +.I /proc/sys/vm/overcommit_ratio +See the description of +.IR /proc/sys/vm/overcommit_memory . +.TP +.I /proc/sysvipc +Subdirectory containing the pseudo-files +.IR msg ", " sem " and " shm "." +These files list the System V Interprocess Communication (IPC) objects +(respectively: message queues, semaphores, and shared memory) +that currently exist on the system, +providing similar information to that available via +.BR ipcs (1). +These files have headers and are formatted (one IPC object per line) +for easy understanding. +.BR ipc (5) +provides further background on the information shown by these files. +.TP +.I /proc/tty +Subdirectory containing the psuedo-files and subdirectories for +tty drivers and line disciplines. +.TP +.I /proc/uptime +This file contains two numbers: the uptime of the system (seconds), +and the amount of time spent in idle process (seconds). +.TP +.I /proc/version +This string identifies the kernel version that is currently running. +It includes the contents of /proc/sys/ostype, /proc/sys/osrelease and +/proc/sys/version. For example: +.nf +.in -2 +.ft CW +Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994 +.ft +.in +2 +.fi +.TP +.IR /proc/vmstat " (since Linux 2.6)" +This file displays various virtual memory statistics. + +.RE +.RE +.SH "SEE ALSO" +.BR cat (1), +.BR find (1), +.BR free (1), +.BR mount (1), +.BR ps (1), +.BR tr (1), +.BR uptime (1), +.BR chroot (2), +.BR mmap (2), +.BR readlink (2), +.BR syslog (2), +.BR slabinfo (5), +.BR hier (7), +.BR arp (8), +.BR dmesg (8), +.BR hdparm (8), +.BR ifconfig (8), +.BR init (8), +.BR lsmod (8), +.BR lspci (8), +.BR netstat (8), +.BR procinfo (8), +.BR route (8) +.br +.I /usr/src/linux/Documentation/filesystems/proc.txt +.SH CAVEATS +Note that many strings (i.e., the environment and command line) are in +the internal format, with sub-fields terminated by NUL bytes, so you +may find that things are more readable if you use \fIod -c\fP or \fItr +"\\000" "\\n"\fP to read them. +Alternatively, \fIecho `cat <file>`\fP works well. + +This manual page is incomplete, possibly inaccurate, and is the kind +of thing that needs to be updated very often. +.SH ACKNOWLEDGEMENTS +The material on /proc/sys/fs and /proc/sys/kernel is closely based on +kernel source documentation files written by Rik van Riel. |