LINK(2)LINK(2)NAME
link - link to a file
SYNOPSIS
#include <unistd.h>
int link(const char *existing, const char *new);
DESCRIPTION
The link() function creates a new link (directory entry) for the exist‐
ing file and increments its link count by one. The existing argument
points to a path name naming an existing file. The new argument points
to a pathname naming the new directory entry to be created.
To create hard links, both files must be on the same file system. Both
the old and the new link share equal access and rights to the underly‐
ing object. Privileged processes can make multiple links to a direc‐
tory. Unless the caller is privileged, the file named by existing must
not be a directory.
Upon successful completion, link() marks for update the st_ctime field
of the file. Also, the st_ctime and st_mtime fields of the directory
that contains the new entry are marked for update.
RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, −1 is returned,
no link is created, and errno is set to indicate the error.
ERRORS
The link() function will fail if:
EACCES
A component of either path prefix denies search permis‐
sion, or the requested link requires writing in a
directory with a mode that denies write permission.
EDQUOT
The directory where the entry for the new link is being
placed cannot be extended because the user's quota of
disk blocks on that file system has been exhausted.
EEXIST
The link named by new exists.
EFAULT
The existing or new argument points to an illegal
address.
EILSEQ
The path argument includes non-UTF8 characters and the
file system accepts only file names where all charac‐
ters are part of the UTF-8 character codeset.
EINTR
A signal was caught during the execution of the link()
function.
ELOOP
Too many symbolic links were encountered in translating
path.
EMLINK
The maximum number of links to a file would be
exceeded.
ENAMETOOLONG
The length of the existing or new argument exceeds
PATH_MAX, or the length of a existing or new component
exceeds NAME_MAX while _POSIX_NO_TRUNC is in effect.
ENOENT
The existing or new argument is a null pathname; a com‐
ponent of either path prefix does not exist; or the
file named by existing does not exist.
ENOLINK
The existing or new argument points to a remote machine
and the link to that machine is no longer active.
ENOSPC
The directory that would contain the link cannot be
extended.
ENOTDIR
A component of either path prefix is not a directory.
EPERM
The file named by existing is a directory and the
{PRIV_SYS_LINKDIR} privilege is not asserted in the
effective set of the calling process.
The effective user ID does not match the owner of the
file and the {PRIV_FILE_LINK_ANY} privilege is not
asserted in the effective set of the calling process.
EROFS
The requested link requires writing in a directory on a
read-only file system.
EXDEV
The link named by new and the file named by existing
are on different logical devices (file systems).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬───────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼───────────────────┤
│Interface Stability │ Standard │
├────────────────────┼───────────────────┤
│MT-Level │ Async-Signal-Safe │
└────────────────────┴───────────────────┘
SEE ALSOsymlink(2), unlink(2), attributes(5), privileges(5), standards(5)
May 18, 2007 LINK(2)
