LINK(2) |
Linux Programmer's Manual |
LINK(2) |
NAME
link - make a new name for a file
SYNOPSIS
#include <unistd.h>
int link(const char *
oldpath
, const char *
newpath
);
DESCRIPTION
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".
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
ERRORS
-
EACCES
-
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).)
-
EDQUOT
-
The user's quota of disk blocks on the file system has been exhausted.
-
EEXIST
-
newpath already exists.
-
EFAULT
-
oldpath or
newpath points outside your accessible address space.
-
EIO
-
An I/O error occurred.
-
ELOOP
-
Too many symbolic links were encountered in resolving
oldpath or
newpath.
-
EMLINK
-
The file referred to by
oldpath already has the maximum number of links to it.
-
ENAMETOOLONG
-
oldpath or
newpath was too long.
-
ENOENT
-
A directory component in
oldpath or
newpath does not exist or is a dangling symbolic link.
-
ENOMEM
-
Insufficient kernel memory was available.
-
ENOSPC
-
The device containing the file has no room for the new directory entry.
-
ENOTDIR
-
A component used as a directory in
oldpath or
newpath is not, in fact, a directory.
-
EPERM
-
oldpath is a directory.
-
EPERM
-
The file system containing
oldpath and
newpath does not support the creation of hard links.
-
EPERM (since Linux 3.6)
-
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)).
-
EROFS
-
The file is on a read-only file system.
-
EXDEV
-
oldpath and
newpath are not on the same mounted file system. (Linux permits a file system to be mounted at multiple points, but
link() does not work across different mount points, even if the same file system is mounted on both.)
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001 (but see NOTES).
NOTES
Hard links, as created by
link(), cannot span file systems. 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).
BUGS
On NFS file systems, 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.
SEE ALSO
ln(1),
linkat(2),
open(2),
rename(2),
stat(2),
symlink(2),
unlink(2),
path_resolution(7),
symlink(7)
COLOPHON
This page is part of release 3.53 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/.