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link — make a new name for a file
#include <unistd.h>
int
link( |
const char *oldpath, |
const char *newpath); |
link() creates a new link
(also known as a hard link) to an existing file.
If newpath exists
it will not be
overwritten.
This new name may be used exactly as the old one for any operation; both names refer to the same file (and so have the same permissions and ownership) and it is impossible to tell which name was the "original".
On success, zero is returned. On error, −1 is
returned, and errno is set
appropriately.
Write access to the directory containing newpath is denied, or
search permission is denied for one of the directories
in the path prefix of oldpath or newpath. (See also
path_resolution(7).)
The user's quota of disk blocks on the filesystem has been exhausted.
newpath
already exists.
oldpath or
newpath points
outside your accessible address space.
An I/O error occurred.
Too many symbolic links were encountered in
resolving oldpath or newpath.
The file referred to by oldpath already has the
maximum number of links to it.
oldpath or
newpath was too
long.
A directory component in oldpath or newpath does not exist or
is a dangling symbolic link.
Insufficient kernel memory was available.
The device containing the file has no room for the new directory entry.
A component used as a directory in oldpath or newpath is not, in fact,
a directory.
oldpath is a
directory.
The filesystem containing oldpath and newpath does not support
the creation of hard links.
The caller does not have permission to create a hard
link to this file (see the description of /proc/sys/fs/protected_hardlink in
proc(5)).
The file is on a read-only filesystem.
oldpath and
newpath are not
on the same mounted filesystem. (Linux permits a
filesystem to be mounted at multiple points, but
link() does not work
across different mount points, even if the same
filesystem is mounted on both.)
Hard links, as created by link(), cannot span filesystems. Use
symlink(2) if this is
required.
POSIX.1-2001 says that link() should dereference oldpath if it is a symbolic
link. However, since kernel 2.0, Linux does not do so: if
oldpath is a symbolic
link, then newpath is
created as a (hard) link to the same symbolic link file
(i.e., newpath
becomes a symbolic link to the same file that oldpath refers to). Some other
implementations behave in the same manner as Linux.
POSIX.1-2008 changes the specification of link(), making it implementation-dependent
whether or not oldpath is dereferenced if it
is a symbolic link. For precise control over the treatment of
symbolic links when creating a link, see linkat(2).
On NFS filesystems, the return code may be wrong in case the NFS server performs the link creation and dies before it can say so. Use stat(2) to find out if the link got created.
ln(1), linkat(2), open(2), rename(2), stat(2), symlink(2), unlink(2), path_resolution(7), symlink(7)
This page is part of release 3.54 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man−pages/.
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This manpage is Copyright (C) 1992 Drew Eckhardt; and Copyright (C) 1993 Michael Haardt, Ian Jackson. %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END Modified 1993-07-23 by Rik Faith <faithcs.unc.edu> Modified 1994-08-21 by Michael Haardt Modified 2004-06-23 by Michael Kerrisk <mtk.manpagesgmail.com> Modified 2005-04-04, as per suggestion by Michael Hardt for rename.2 |