mirror of https://github.com/mkerrisk/man-pages
176 lines
4.8 KiB
Groff
176 lines
4.8 KiB
Groff
.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
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.\" 1993 Michael Haardt, Ian Jackson.
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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.\" manual page may be incorrect or out-of-date.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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.\" Modified 1993-07-23 by Rik Faith <faith@cs.unc.edu>
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.\" Modified 1994-08-21 by Michael Haardt
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.\" Modified 2004-06-23 by Michael Kerrisk <mtk-manpages@gmx.net>
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.\" Modified 2005-04-04, as per suggestion by Michael Hardt for rename.2
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.\"
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.TH LINK 2 2004-06-23 "Linux 2.6.7" "Linux Programmer's Manual"
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.SH NAME
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link \- make a new name for a file
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.SH SYNOPSIS
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.B #include <unistd.h>
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.sp
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.BI "int link(const char *" oldpath ", const char *" newpath );
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.SH DESCRIPTION
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.BR link ()
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creates a new link (also known as a hard link) to an existing file.
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If
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.I newpath
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exists it will
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.I not
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be overwritten.
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This new name may be used exactly as the old one for any operation;
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both names refer to the same file (and so have the same permissions
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and ownership) and it is impossible to tell which name was the
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\`original'.
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.SH "RETURN VALUE"
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On success, zero is returned.
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On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EACCES
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Write access to the directory containing
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.I newpath
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is denied, or search permission is denied for one of the directories
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in the path prefix of
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.I oldpath
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or
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.IR newpath .
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(See also
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.BR path_resolution (2).)
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.TP
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.B EEXIST
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.I newpath
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already exists.
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.TP
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.B EFAULT
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.IR oldpath " or " newpath " points outside your accessible address space."
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.TP
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.B EIO
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An I/O error occurred.
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.TP
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.B ELOOP
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Too many symbolic links were encountered in resolving
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.IR oldpath " or " newpath .
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.TP
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.B EMLINK
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The file referred to by
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.I oldpath
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already has the maximum number of links to it.
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.TP
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.B ENAMETOOLONG
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.IR oldpath " or " newpath " was too long."
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.TP
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.B ENOENT
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A directory component in
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.IR oldpath " or " newpath
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does not exist or is a dangling symbolic link.
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.TP
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.B ENOMEM
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Insufficient kernel memory was available.
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.TP
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.B ENOSPC
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The device containing the file has no room for the new directory
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entry.
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.TP
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.B ENOTDIR
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A component used as a directory in
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.IR oldpath " or " newpath
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is not, in fact, a directory.
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.TP
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.B EPERM
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.I oldpath
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is a directory.
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.TP
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.B EPERM
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The filesystem containing
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.IR oldpath " and " newpath
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does not support the creation of hard links.
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.TP
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.B EROFS
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The file is on a read-only filesystem.
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.TP
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.B EXDEV
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.IR oldpath " and " newpath
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are not on the same mounted filesystem.
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(Linux permits a filesystem to be mounted at multiple points, but
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.BR link (2)
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does not work across different mount points,
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even if the same filesystem is mounted on both.)
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.SH NOTES
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Hard links, as created by
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.BR link (),
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cannot span filesystems.
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Use
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.BR symlink ()
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if this is required.
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POSIX.1-2001 says that
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.BR link ()
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should dereference
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.I oldpath
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if it is a symbolic link.
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However, Linux does not do so: if
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.I oldpath
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is a symbolic link, then
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.I newpath
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is created as a (hard) link to the same symbolic link file
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(i.e.,
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.I newpath
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becomes a symbolic link to the same file that
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.I oldpath
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refers to).
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Some other implementations behave in the same manner as Linux.
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.\" For example, the default Solaris compilation environment
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.\" behaves like Linux, and contributors to a March 2005
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.\" thread in the Austin mailing list reported that some
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.\" other (System V) implementations did/do the same -- MTK, Apr 05
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, POSIX.1-2001 (except as noted above).
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.\" SVr4 documents additional ENOLINK and
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.\" EMULTIHOP error conditions; POSIX.1 does not document ELOOP.
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.\" X/OPEN does not document EFAULT, ENOMEM or EIO.
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.SH BUGS
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On NFS file systems, the return code may be wrong in case the NFS server
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performs the link creation and dies before it can say so.
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Use
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.BR stat (2)
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to find out if the link got created.
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.SH "SEE ALSO"
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.BR ln (1),
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.BR linkat (2),
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.BR open (2),
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.BR path_resolution (2),
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.BR rename (2),
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.BR stat (2),
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.BR symlink (2),
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.BR unlink (2)
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