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/.