LINK(2) BSD System Calls Manual LINK(2)
NAME
link -- make a hard file link
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
int
link(const char *name1, const char *name2);
int
linkat(int fd1, const char *name1, int fd2, const char *name2, int flags);
DESCRIPTION
The link() function call atomically creates the specified directory entry (hard link) name2 with the attributes of the underlying object
pointed at by name1. If the link is successful: the link count of the underlying object is incremented; name1 and name2 share equal access
and rights to the underlying object.
If name1 is removed, the file name2 is not deleted and the link count of the underlying object is decremented.
name1 must exist for the hard link to succeed and both name1 and name2 must be in the same file system. name1 may not be a directory unless
the caller is the super-user and the file system containing it supports linking to directories.
When operating on a symlink, link() resolves the symlink and creates a hard link on the target. linkat() will do the same if
AT_SYMLINK_FOLLOW is set in flags, but it will link on the symlink itself if the flag is clear.
At the moment, linkat() is partially implemented. It will return ENOSYS for fd1 and fd2 values different than AT_FDCWD.
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:
[EACCES] A component of either path prefix denies search permission, or the requested link requires writing in a directory with a
mode that denies write permission.
[EDQUOT] The directory in which the entry for the new link is being placed cannot be extended because the user's quota of disk
blocks on the file system containing the directory has been exhausted.
[EEXIST] The link named by name2 does exist.
[EFAULT] One of the pathnames specified is outside the process's allocated address space.
[EIO] An I/O error occurred while reading from or writing to the file system to make the directory entry.
[ELOOP] Too many symbolic links were encountered in translating one of the pathnames.
[EMLINK] The link count of the file named by name1 would exceed {LINK_MAX}.
[ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters.
[ENOENT] A component of either path prefix does not exist, or the file named by name1 does not exist.
[ENOSPC] The directory in which the entry for the new link is being placed cannot be extended because there is no space left on the
file system containing the directory.
[ENOTDIR] A component of either path prefix is not a directory.
[EOPNOTSUPP] The file system containing the file named by name1 does not support links.
[EPERM] The file named by name1 is a directory and the effective user ID is not super-user, or the file system containing the file
does not permit the use of link() on a directory.
[EROFS] The requested link requires writing in a directory on a read-only file system.
[EXDEV] The link named by name2 and the file named by name1 are on different file systems.
SEE ALSO
symlink(2), unlink(2)
STANDARDS
The link() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').
BUGS
linkat() is partially implemented.
BSD
January 12, 1994 BSD