link - link to a file
int link(const char *existing, const char *new);
The link() function creates a new link (directory entry) for
the existing 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 underlying object. The super-user may make
multiple links to a directory. Unless the caller is the
super-user, the file named by existing must not be a direc-
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.
Upon successful completion, 0 is returned. Otherwise, -1 is
returned, no link is created, and errno is set to indicate
The link() function will fail if:
A component of either path prefix denies search per-
mission, or the requested link requires writing in a
directory with a mode that denies write permission.
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
The link named by new exists.
The existing or new argument points to an illegal
EINTR A signal was caught during the execution of the link()
ELOOP Too many symbolic links were encountered in translat-
The maximum number of links to a file would be
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.
The existing or new argument is a null pathname; a
component of either path prefix does not exist; or the
file named by existing does not exist.
The existing or new argument points to a remote
machine and the link to that machine is no longer
The directory that would contain the link cannot be
A component of either path prefix is not a directory.
EPERM The file named by existing is a directory and the
effective user of the calling process is not super-
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).
When a UFS file system is mounted with logging enabled, file
system transactions that free blocks from files might not
actually add those freed blocks to the file system's free
list until some unspecified time in the future. This
behavior improves file system performance but does not con-
form to the POSIX, Single UNIX Specification, SPARC Confor-
mance Definition, System V Application Binary Interface,
System V Interface Definition, and X/Open Portability Guide
Standards, which require that freed space be available
immediately. To enable standards conformance regarding file
deletions or to address the problem of not being able to
grow files on a relatively full UFS file system even after
files have been deleted, disable UFS logging (see
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | Async-Signal-Safe |
mount_ufs(1M), symlink(2), unlink(2), attributes(5)
Man(1) output converted with