mirror of https://github.com/mkerrisk/man-pages
141 lines
3.5 KiB
Groff
141 lines
3.5 KiB
Groff
.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" This manpage is Copyright (C) 2006, Michael Kerrisk
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\"
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.TH LINKAT 2 2006-04-10 "Linux 2.6.16" "Linux Programmer's Manual"
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.SH NAME
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linkat \- create a file link relative to directory file descriptors
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.SH SYNOPSIS
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.nf
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.B #define _ATFILE_SOURCE
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.B #include <unistd.h>
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.sp
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.BI "int linkat(int " olddirfd ", const char *" oldpath ,
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.BI " int " newdirfd ", const char *" newpath ", int " flags );
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.fi
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.SH DESCRIPTION
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The
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.BR linkat ()
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system call operates in exactly the same way as
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.BR link (2),
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except for the differences described in this manual page.
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If the pathname given in
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.I oldpath
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is relative, then it is interpreted relative to the directory
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referred to by the file descriptor
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.IR olddirfd
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(rather than relative to the current working directory of
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the calling process, as is done by
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.BR link (2)
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for a relative pathname).
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If
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.I oldpath
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is relative and
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.I olddirfd
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is the special value
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.BR AT_FDCWD ,
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then
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.I oldpath
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is interpreted relative to the current working
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directory of the calling process (like
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.BR link (2)).
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If
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.IR oldpath
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is absolute, then
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.I olddirfd
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is ignored.
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The interpretation of
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.I newpath
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is as for
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.IR oldpath ,
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except that a relative pathname is interpreted relative
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to the directory referred to by the file descriptor
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.IR newdirfd .
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By default,
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.BR linkat (2),
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does not dereference
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.I oldpath
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if it is a symbolic link (like
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.BR link (2)).
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Since Linux 2.6.18, the flag
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.B AT_SYMLINK_FOLLOW
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can be specified
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.I flags
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to cause
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.I oldpath
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to be dereferenced if it is a symbolic link.
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Before kernel 2.6.18, the
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.I flags
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argument was unused, and had to be specified as 0.
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.SH "RETURN VALUE"
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On success,
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.BR linkat ()
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returns 0.
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On error, \-1 is returned and
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.I errno
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is set to indicate the error.
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.SH ERRORS
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The same errors that occur for
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.BR link (2)
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can also occur for
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.BR linkat ().
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The following additional errors can occur for
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.BR linkat ():
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.TP
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.B EBADF
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.I olddirfd
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or
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.I newdirfd
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is not a valid file descriptor.
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.TP
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.B ENOTDIR
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.I oldpath
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is relative and
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.I olddirfd
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is a file descriptor referring to a file other than a directory;
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or similar for
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.I newpath
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and
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.IR newdirfd
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.SH NOTES
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See
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.BR openat (2)
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for an explanation of the need for
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.BR linkat ().
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.SH "CONFORMING TO"
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This system call is non-standard but is proposed
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for inclusion in a future revision of POSIX.1.
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.SH VERSIONS
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.BR linkat ()
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was added to Linux in kernel 2.6.16.
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.SH "SEE ALSO"
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.BR link (2),
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.BR openat (2),
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.BR path_resolution (2)
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