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diff --git a/man-pages-posix-2013/man1p/ln.1p b/man-pages-posix-2013/man1p/ln.1p new file mode 100644 index 0000000..d3e62a0 --- /dev/null +++ b/man-pages-posix-2013/man1p/ln.1p @@ -0,0 +1,469 @@ +'\" et +.TH LN "1P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. + +.SH NAME +ln +\(em link files +.SH SYNOPSIS +.LP +.nf +ln \fB[\fR\(mifs\fB] [\fR\(miL|\(miP\fB] \fIsource_file target_file\fR +.P +ln \fB[\fR\(mifs\fB] [\fR\(miL|\(miP\fB] \fIsource_file\fR... \fItarget_dir\fR +.fi +.SH DESCRIPTION +In the first synopsis form, the +.IR ln +utility shall create a new directory entry (link) at the +destination path specified by the +.IR target_file +operand. If the +.BR \(mis +option is specified, a symbolic link shall be created for the file +specified by the +.IR source_file +operand. This first synopsis form shall be assumed when the final +operand does not name an existing directory; if more than two operands +are specified and the final is not an existing directory, an error +shall result. +.P +In the second synopsis form, the +.IR ln +utility shall create a new directory entry (link), or if the +.BR \(mis +option is specified a symbolic link, for each file specified by a +.IR source_file +operand, at a destination path in the existing directory named by +.IR target_dir . +.P +If the last operand specifies an existing file of a type not +specified by the System Interfaces volume of POSIX.1\(hy2008, the behavior is implementation-defined. +.P +The corresponding destination path for each +.IR source_file +shall be the concatenation of the target directory pathname, a +<slash> +character if the target directory pathname did not end in a +<slash>, +and the last pathname component of the +.IR source_file . +The second synopsis form shall be assumed when the final operand names +an existing directory. +.P +For each +.IR source_file : +.IP " 1." 4 +If the destination path exists and was created by a previous step, +it is unspecified whether +.IR ln +shall write a diagnostic message to standard error, do nothing more with +the current +.IR source_file , +and go on to any remaining +.IR source_file s; +or will continue processing the current +.IR source_file . +If the destination path exists: +.RS 4 +.IP " a." 4 +If the +.BR \(mif +option is not specified, +.IR ln +shall write a diagnostic message to standard error, do nothing more +with the current +.IR source_file , +and go on to any remaining +.IR source_file s. +.IP " b." 4 +If +.IR destination +names the same directory entry as the current +.IR source_file +.IR ln +shall write a diagnostic message to standard error, do nothing more with +the current +.IR source_file , +and go on to any remaining +.IR source_file s . +.IP " c." 4 +Actions shall be performed equivalent to the +\fIunlink\fR() +function defined in the System Interfaces volume of POSIX.1\(hy2008, called using +.IR destination +as the +.IR path +argument. If this fails for any reason, +.IR ln +shall write a diagnostic message to standard error, do nothing more +with the current +.IR source_file , +and go on to any remaining +.IR source_file s. +.RE +.IP " 2." 4 +If the +.BR \(mis +option is specified, actions shall be performed equivalent to the +\fIsymlink\fR() +function with +.IR source_file +as the +.IR path1 +argument and the destination path as the +.IR path2 +argument. The +.IR ln +utility shall do nothing more with +.IR source_file +and shall go on to any remaining files. +.IP " 3." 4 +If +.IR source_file +is a symbolic link: +.RS 4 +.IP " a." 4 +If the +.BR \(miP +option is in effect, actions shall be performed equivalent to the +\fIlinkat\fR() +function with +.IR source_file +as the +.IR path1 +argument, the destination path as the +.IR path2 +argument, AT_FDCWD as the +.IR fd1 +and +.IR fd2 +arguments, and zero as the +.IR flag +argument. +.IP " b." 4 +If the +.BR \(miL +option is in effect, actions shall be performed equivalent to the +\fIlinkat\fR() +function with +.IR source_file +as the +.IR path1 +argument, the destination path as the +.IR path2 +argument, AT_FDCWD as the +.IR fd1 +and +.IR fd2 +arguments, and AT_SYMLINK_FOLLOW as the +.IR flag +argument. +.P +The +.IR ln +utility shall do nothing more with +.IR source_file +and shall go on to any remaining files. +.RE +.IP " 4." 4 +Actions shall be performed equivalent to the +\fIlink\fR() +function defined in the System Interfaces volume of POSIX.1\(hy2008 using +.IR source_file +as the +.IR path1 +argument, and the destination path as the +.IR path2 +argument. +.SH OPTIONS +The +.IR ln +utility shall conform to the Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 12.2" ", " "Utility Syntax Guidelines". +.P +The following options shall be supported: +.IP "\fB\(mif\fP" 10 +Force existing destination pathnames to be removed to allow the link. +.IP "\fB\(miL\fP" 10 +For each +.IR source_file +operand that names a file of type symbolic link, create a (hard) +link to the file referenced by the symbolic link. +.IP "\fB\(miP\fP" 10 +For each +.IR source_file +operand that names a file of type symbolic link, create a (hard) +link to the symbolic link itself. +.IP "\fB\(mis\fP" 10 +Create symbolic links instead of hard links. If the +.BR \(mis +option is specified, the +.BR \(miL +and +.BR \(miP +options shall be silently ignored. +.P +Specifying more than one of the mutually-exclusive options +.BR \(miL +and +.BR \(miP +shall not be considered an error. The last option specified shall +determine the behavior of the utility (unless the +.BR \(mis +option causes it to be ignored). +.P +If the +.BR \(mis +option is not specified and neither a +.BR \(miL +nor a +.BR \(miP +option is specified, it is implementation-defined which of the +.BR \(miL +and +.BR \(miP +options will be used as the default. +.SH OPERANDS +The following operands shall be supported: +.IP "\fIsource_file\fR" 10 +A pathname of a file to be linked. If the +.BR \(mis +option is specified, no restrictions on the type of file or on its +existence shall be made. If the +.BR \(mis +option is not specified, whether a directory can be linked is +implementation-defined. +.IP "\fItarget_file\fR" 10 +The pathname of the new directory entry to be created. +.IP "\fItarget_dir\fR" 10 +A pathname of an existing directory in which the new directory entries +are created. +.SH STDIN +Not used. +.SH "INPUT FILES" +None. +.SH "ENVIRONMENT VARIABLES" +The following environment variables shall affect the execution of +.IR ln : +.IP "\fILANG\fP" 10 +Provide a default value for the internationalization variables that are +unset or null. (See the Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 8.2" ", " "Internationalization Variables" +for the precedence of internationalization variables used to determine +the values of locale categories.) +.IP "\fILC_ALL\fP" 10 +If set to a non-empty string value, override the values of all the +other internationalization variables. +.IP "\fILC_CTYPE\fP" 10 +Determine the locale for the interpretation of sequences of bytes of +text data as characters (for example, single-byte as opposed to +multi-byte characters in arguments). +.IP "\fILC_MESSAGES\fP" 10 +.br +Determine the locale that should be used to affect the format and +contents of diagnostic messages written to standard error. +.IP "\fINLSPATH\fP" 10 +Determine the location of message catalogs for the processing of +.IR LC_MESSAGES . +.SH "ASYNCHRONOUS EVENTS" +Default. +.SH STDOUT +Not used. +.SH STDERR +The standard error shall be used only for diagnostic messages. +.SH "OUTPUT FILES" +None. +.SH "EXTENDED DESCRIPTION" +None. +.SH "EXIT STATUS" +The following exit values shall be returned: +.IP "\00" 6 +All the specified files were linked successfully. +.IP >0 6 +An error occurred. +.SH "CONSEQUENCES OF ERRORS" +Default. +.LP +.IR "The following sections are informative." +.SH "APPLICATION USAGE" +None. +.SH EXAMPLES +None. +.SH RATIONALE +The CONSEQUENCES OF ERRORS section does not require +.IR ln +.BR \(mif +.IR "a b" +to remove +.IR b +if a subsequent link operation would fail. +.P +Some historic versions of +.IR ln +(including the one specified by the SVID) unlink the destination file, +if it exists, by default. If the mode does not permit writing, these +versions prompt for confirmation before attempting the unlink. In these +versions the +.BR \(mif +option causes +.IR ln +not to attempt to prompt for confirmation. +.P +This allows +.IR ln +to succeed in creating links when the target file already exists, even +if the file itself is not writable (although the directory must be). +Early proposals specified this functionality. +.P +This volume of POSIX.1\(hy2008 does not allow the +.IR ln +utility to unlink existing destination paths by default for the +following reasons: +.IP " *" 4 +The +.IR ln +utility has historically been used to provide locking for shell +applications, a usage that is incompatible with +.IR ln +unlinking the destination path by default. There was no corresponding +technical advantage to adding this functionality. +.IP " *" 4 +This functionality gave +.IR ln +the ability to destroy the link structure of files, which changes the +historical behavior of +.IR ln . +.IP " *" 4 +This functionality is easily replicated with a combination of +.IR rm +and +.IR ln . +.IP " *" 4 +It is not historical practice in many systems; BSD and BSD-derived +systems do not support this behavior. Unfortunately, whichever behavior +is selected can cause scripts written expecting the other behavior to +fail. +.IP " *" 4 +It is preferable that +.IR ln +perform in the same manner as the +\fIlink\fR() +function, which does not permit the target to exist already. +.P +This volume of POSIX.1\(hy2008 retains the +.BR \(mif +option to provide support for shell scripts depending on the SVID +semantics. It seems likely that shell scripts would not be written to +handle prompting by +.IR ln +and would therefore have specified the +.BR \(mif +option. +.P +The +.BR \(mif +option is an undocumented feature of many historical versions of the +.IR ln +utility, allowing linking to directories. These versions require +modification. +.P +Early proposals of this volume of POSIX.1\(hy2008 also required a +.BR \(mii +option, which behaved like the +.BR \(mii +options in +.IR cp +and +.IR mv , +prompting for confirmation before unlinking existing files. This was +not historical practice for the +.IR ln +utility and has been omitted. +.P +The +.BR \(miL +and +.BR \(miP +options allow for implementing both common behaviors of the +.IR ln +utility. Earlier versions of this standard did not specify these options +and required the behavior now described for the +.BR \(miL +option. Many systems by default or as an alternative provided a +non-conforming +.IR ln +utility with the behavior now described for the +.BR \(miP +option. Since applications could not rely on +.IR ln +following links in practice, the +.BR \(miL +and +.BR \(miP +options were added to specify the desired behavior for the application. +.P +The +.BR \(miL +and +.BR \(miP +options are ignored when +.BR \(mis +is specified in order to allow an alias to be created to alter the +default behavior when creating hard links (for example, +.IR alias +.IR ln ='\c +.IR ln +.BR \(miL '). +They serve no purpose when +.BR \(mis +is specified, since +.IR source_file +is then just a string to be used as the contents of the created symbolic +link and need not exist as a file. +.P +The specification ensures that +.IR ln +.BR a +.BR a +with or without the +.BR \(mif +option will not unlink the file +.BR a . +Earlier versions of this standard were unclear in this case. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "\fIchmod\fR\^", +.IR "\fIfind\fR\^", +.IR "\fIpax\fR\^", +.IR "\fIrm\fR\^" +.P +The Base Definitions volume of POSIX.1\(hy2008, +.IR "Chapter 8" ", " "Environment Variables", +.IR "Section 12.2" ", " "Utility Syntax Guidelines" +.P +The System Interfaces volume of POSIX.1\(hy2008, +.IR "\fIlink\fR\^(\|)", +.IR "\fIunlink\fR\^(\|)" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, Copyright (C) 2013 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the +event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.unix.org/online.html . + +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |