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Name

link - link to a file

Synopsis

#include <unistd.h>

int link(const char *existing, const char *new);

MT-Level

Async-Signal-Safe

Description

link() creates a new link (directory entry) for the existing file and increments its link count by one. existing points to a path name naming an existing file. new points to a path name 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 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, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

Errors

link() will fail and no link will be created if one or more of the following are true:

EACCES
A component of either path prefix denies search permission.
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
existing or new points to an illegal address.
EINTR
A signal was caught during 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.
EMULTIHOP
Components of existing or new require hopping to multiple remote machines and the file system type does not allow it.
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
existing or new is a null path name.
A component of either path prefix does not exist.
The file named by
existing does not exist.
ENOLINK
existing or new points to a remote machine and the link to that machine is no longer active.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 effective user of the calling process is not super-user.
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).

See Also

symlink(2) , unlink(2)

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