LINK(2) Linux Programmer's Manual LINK(2)
link - make a new name for a file
int link(const char *oldpath, const char *newpath);
link() creates a new link (also known as a hard link) to an existing
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
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_resolu-
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
EMLINK The file referred to by oldpath already has the maximum number
of links to it.
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
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.
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.)
SVr4, 4.3BSD, POSIX.1-2001 (except as noted above).
Hard links, as created by link(), cannot span file systems. Use sym-
link(2) if this is required.
POSIX.1-2001 says that link() should dereference oldpath if it is a
symbolic link. However, 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 man-
ner as Linux.
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.
ln(1), linkat(2), open(2), rename(2), stat(2), symlink(2), unlink(2),
This page is part of release 3.05 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/.
Linux 2004-06-23 LINK(2)